DETERMINING TIP SEAL MAINTENANCE REQUIREMENT IN SCROLL PUMP

Abstract

A scroll pump or pumping system is configured to determine whether tip seals of the scroll pump require maintenance such as replacement. During operation of the scroll pump, pump inlet pressure is measured or calculated over a recent time period to acquire recent pump data. The recent pump data is compared to historical pump data, which is or includes pump inlet pressure measured over a historical time period preceding the recent time period. Based on the comparison, a determination is made as to whether tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required. If so, a user-interpretable output may be produced, indicating that tip seal maintenance and/or further diagnosis is required.

Description

TECHNICAL FIELD

The present invention relates to scroll pumps, particularly to maintenance or servicing of scroll pumps, and more particularly to replacement of tip seals of scroll pumps.

BACKGROUND

Scroll pumps are widely utilized as compressors for supplying a pressurized working fluid (e.g., compressed air, refrigerant, etc.) and as vacuum pumps for evacuating a chamber by removing a working fluid from the chamber. As appreciated by the skilled artisan, a scroll pump has at least one pumping (or compression) stage formed by an orbiting scroll and a fixed (stationary) scroll. The orbiting scroll has an orbiting scroll blade extending in an axial direction from a radially oriented orbiting scroll plate (or base) toward the fixed scroll. The fixed scroll has a fixed scroll blade extending in the opposite axial direction from a radially oriented fixed scroll plate (or base) toward the orbiting scroll. The scroll blades (or “wraps”) are spiral-shaped. That is, each scroll blade runs along a spiral path in multiple revolutions around the central region of its corresponding scroll plate. The orbiting and fixed scroll blades are nested with each other. The scroll pump further has a motor-driven crankshaft that rotates about its central shaft axis, or drive axis. The crankshaft has an eccentrically positioned crank located at the end of the crankshaft that is opposite to the motor. The central axis of the crank is radially offset from the drive axis of the main part of the crankshaft. Thus, as the main part of the crankshaft rotates about the drive axis, the crank orbits in a circle (whose radius corresponds to the radial offset distance) around the drive axis. The orbiting scroll is coupled to the crank and thus orbits with the crank, but without the orbiting scroll itself rotating on its own axis.

In operation, the orbiting scroll is driven by the crankshaft to orbit around the drive axis relative to the fixed scroll to create one or more moving, variable-volume pumping chambers or zones, also referred to as “pockets”, between the orbiting scroll blade and the fixed scroll blade. Each pocket is defined between and bounded by adjacent sections of the orbiting scroll blade and the fixed scroll blade. As the orbiting scroll orbits, the pockets receive the (gas-phase or liquid-phase) working fluid from a pump inlet and displace (transport or convey) the working fluid to a pump outlet. As the pockets move in accordance with the orbiting motion, the volume of the space inside the pockets decreases, thereby compressing the working fluid to some degree as the working fluid is being displaced toward the pump outlet.

An example of the structure and operation of such a scroll pump is described in U.S. Pat. No. 5,855,473, the entire contents of which are incorporated by reference herein.

A scroll pump may have more than one pumping stage, such as two pumping stages fluidly connected in series. For example, the orbiting scroll may be positioned between two fixed scrolls, namely, a fixed outboard scroll having a fixed outboard scroll blade and a fixed inboard scroll having a fixed inboard scroll blade. In this case, the orbiting scroll has one orbiting scroll blade on its inboard side and another orbiting scroll blade on its outboard side. The orbiting outboard scroll blade is nested with the fixed outboard scroll blade to cooperatively define one (outboard) pumping stage, and the orbiting inboard scroll blade is nested with the fixed inboard scroll blade to cooperatively define another (inboard) pumping stage, In operation, the first pumping stage (either the outboard stage or the inboard stage, depending on configuration) receives the working fluid from the pump inlet, compresses the working fluid, and transfers the compressed working fluid to the second pumping stage. The second pumping stage further compresses the working fluid and discharges the further compressed working fluid toward the pump outlet. An example of such a two-stage scroll pump is described in above-referenced U.S. Pat. No. 5,855,473.

In either a single-stage or multi-stage scroll pump, the orbiting scroll and the fixed scroll(s) may not contact each other. Instead, small axial gaps exist between the blade tips (free ends) of each scroll blade and the surfaces of the scroll plates that are immediately axially adjacent to and facing those corresponding blade tips. For example, on a given (outboard or inboard) side of the orbiting scroll plate, the blade tip of the orbiting scroll blade is spaced from the surface of the fixed scroll plate by an axial gap. Likewise, on the same side, the blade tip of the fixed scroll blade is spaced from the surface of the orbiting scroll plate by an axial gap. The axial gaps are necessary so that the orbiting scroll may move with respect to the fixed scroll(s). The scroll pump may be a “dry” scroll pump, meaning that it is not sealed or lubricated by a liquid such as oil. In this case, the axial gaps are closed and sealed by tip seals mounted to the respective blade tips, such that each tip seal runs continuously along the same spiral path as its corresponding scroll blade. The tip seals enhance the sealing interfaces between the orbiting scroll and the fixed scroll(s) without impairing the motion of the orbiting scroll.

In an alternative configuration, a scroll pump may be configured as a co-rotating scroll pump. In this case, for a given pumping stage, both scrolls orbit relative to each other. The scroll directly powered by the drive shaft may be termed the drive scroll and the other scroll may be termed the driven scroll. An example of a co-rotating scroll pump is described in U.S. Pat. No. 5,256,042, the entire contents of which are incorporated by reference herein.

In the pumping stage, leakage of the working fluid (e.g., air) occurs at both the flank clearances and across the tip seal (at the axial gap). This leakage reduces the total effectiveness of the scroll pump. As the scroll pump is operated over the long term, the tip seals wear due to their to sliding contact (e.g., rubbing) between the tip seals and the opposing, adjacent surfaces of the corresponding scroll plates (at the respective axial gaps noted above), with the sliding contact occurring at least intermittently. Over time, the leakage across the tip seals increases due to this wear and the user is periodically required to place the tips seals. Tip seal replacement generally requires the user to shut down the scroll pump and the processing being supported by the scroll pump, and at least partially disassemble the pump head to gain access to the tip seals of the orbiting scroll and fixed scroll(s).

In general, as the tip seals of a scroll pump wear, the pump's inlet pressure for a given gas flow condition will increase. If the normal operating condition of the scroll pump in its application is with zero gas flow, the inlet pressure is referred to as the scroll pump's base pressure. In some other applications, a generally constant gas flow is applied, and the inlet pressure is expected to remain generally constant. In yet other applications, the scroll pump is repeatedly connected to a system, for example to exhaust air from a chamber. In such cases, the inlet pressure after a certain amount of time is expected to remain generally constant with each successive pump-down cycle. FIG. 1 is a graph plotting pump inlet pressure versus time that illustrates typical patterns for the three common types of applications (or operational modes) of a scroll pump. Plot (a) represents no gas load, plot (b) represents a constant gas load, and plot (c) represents a series of repeated pump-downs. Small fluctuations in inlet pressure are seen to occur during short-term time intervals (e.g., on the scale of a few minutes or few seconds). The small fluctuations may relate to small variations in operating conditions of the scroll pump and are not attributed to tip seal wear. Over the long-term time period shown in FIG. 1, the target inlet pressure is seen to remain generally constant, which assumes that significant tip seal wear has not yet occurred.

In all the types of applications described above (with zero gas load, or with a constant gas load, or after a certain amount of time in each of a series of repeated pump-downs), the user's expectation is that the pump's inlet pressure will stay generally constant. As the scroll pump's tip seals wear, the inlet pressure in all such applications will remain constant for a long time. Then, as the wear of the tip seals progresses with further pump operation, the leakage across the tip seals continues to be greater, and the inlet pressure begins rising with an increasing slope, until the user's application is adversely affected and tip seal replacement becomes necessary.

FIG. 2 shows a typical pattern of pump inlet pressure versus time over the life of a scroll pump's tip seals, with dots representing individual measurements. This pattern is characteristic of both applications with zero gas load and applications with constant gas load. FIG. 2 shows that over an initial time period of operation of the scroll pump (e.g., about one year), the pump inlet pressure is fairly constant because significant tip seal wear has not occurred. However, with continued operation of the scroll pump, the pump inlet pressure increases, which is due to an increasing amount of tip seal wear. FIG. 3 shows a typical pattern of pump inlet pressure vs. time over the life of a scroll pump's tip seals for an application with repetitive pump-down cycles of constant duration. FIG. 3 shows that over an initial time period of operation of the scroll pump, the pump inlet pressure (the target pump-down pressure, or vacuum level attained at the end of each pump-down cycle) is fairly constant because significant tip seal wear has not occurred. However, with continued operation of the scroll pump, the pump inlet pressure at the end of each pump-down cycle increases, which is due to an increasing amount of tip seal wear. FIG. 4 shows a typical pattern of pump inlet pressure vs. time over the life of a scroll pump's tip seals for an application with repetitive pump-down cycles, where each pump-down cycle continues (i.e., the duration of the pump-down cycle is varied) until a target pump inlet pressure is reached. FIG. 4 shows that over an initial time period of operation of the scroll pump, the time needed to reach the target pump inlet pressure in a given pump-down cycle (i.e., the duration of the pump-down cycles) is fairly constant because significant tip seal wear has not occurred. However, with continued operation of the scroll pump, the time needed to reach the target pump inlet pressure in a given pump-down cycle increases, which is due to an increasing amount of tip seal wear. Note that the time scale in FIGS. 2-4 is much longer than that of FIG. 1.

One current practice in assessing whether tip seal replacement is required calls for the user to disconnect the scroll pump from the process it supports (e.g., a vacuum chamber of a system), mount a vacuum gauge, and operate the pump for at least one hour to establish ultimate pressure (i.e., the lowest pressure achievable by the scroll pump with no gas load). In many cases, the scroll pump is loaded with process materials (e.g., drawn from the chamber being evacuated) absorbed into internal structures of the scroll pump, or adsorbed onto interior surfaces of the scroll pump, and it may take much longer than one hour to establish an ultimate pressure value.

Another current practice is to implement a standard maintenance interval, for example, one year, at which the tip seals are pre-emptively replaced. However, due to variation in the performance of individual scroll pumps, sometimes the tip seals are replaced long before replacement is needed, and other times the tip seals need unscheduled replacement before the planned service interval.

Moreover, during operation of a scroll pump, from minute to minute, inlet pressure can vary considerably. Furthermore, some applications may involve different gas loads that result in different inlet pressures. In addition, users may alter their vacuum system, perform service on other components of the system, or otherwise perform actions on the system that cause short-term variation in the inlet pressure. As a result, simply monitoring inlet pressure and assuming that inlet pressure above a given setpoint or threshold value indicates a need for tip seal replacement can lead to excessive false indications of tip seal wear-out.

Therefore, it would be desirable that the user be able to know, well in advance if desired, whether the time is approaching for a tip seal replacement, so that this work can be done, for example, at the time of a regularly scheduled maintenance activity and/or before the tip seal wears to a point where the scroll pump starts to lose its vacuum performance (which might indicate the need for tip seal replacement before a regularly scheduled maintenance activity). In certain applications, it can be very costly and undesirable to have an unplanned shutdown due to the need to replace a worn tip seal.

In view of the foregoing, there is a need for effective solutions regarding the diagnosis of scroll pumps, including determining when replacement of tip seals in scroll pumps is needed.

SUMMARY

To address the foregoing problems, in whole or in part, and/or other problems that may have been observed by persons skilled in the art, the present disclosure provides methods, processes, systems, apparatus, instruments, and/or devices, as described by way of example in implementations set forth below.

According to some implementations, the present disclosure provides a method and/or apparatus and/or system that allow a user to assess the condition of a scroll pump's tip seals without requiring the disconnection of the scroll pump from the system or a lengthy pump-down cycle.

According to some implementations, the present disclosure provides a method and apparatus (e.g., scroll pump) and/or system (e.g., a system or process that includes at least one vacuum chamber connectable to a scroll pump) that capture the essential pattern of pump inlet pressure over time with tip seal wear-out, such as illustrated in FIGS. 2-4, but without excessive false alarms. For this purpose, the method and/or apparatus and/or system may, for example, execute algorithms or processes that utilize stored data of inlet pressure. The scroll pump may include an onboard pressure gauge at (or near) the pump inlet, whereby inlet pressure data may be stored over time and calculations or determinations may be performed on the stored data. Alternatively or additionally, the scroll pump may include other types of sensors that output measurement signals from which the pump inlet pressure may be calculated or derived, such as a voltage sensor and/or a current sensor that monitor(s) the operation of a motor of the scroll pump. The method and/or apparatus and/or system may be configured (e.g., by executing algorithms or processes disclosed herein) to distinguish between short-term fluctuations in pressure that are of no significance, versus long-term steady increases in pressure that may indicate that tip seal wear-out is imminent. When the assessment algorithm or process determines that tip seal wear-out may be imminent, an alarm and/or other indication or communication to the user may be produced or outputted. For example, method and/or apparatus and/or system may warn the user that it is time to schedule service on the scroll pump, whether that be further diagnosis or the replacement of the tip seals or both.

According to an implementation, a method for assessing scroll pump tip seal wear in a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: providing a scroll pump comprising a pump inlet, a pump outlet, and a pumping stage, wherein the pumping stage comprises a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to create a moving pocket between the first scroll and the second scroll effective to pump fluid from the pump inlet to the pump outlet, the first scroll comprises a first scroll tip seal, and the second scroll comprises a second scroll tip seal. The method further includes: providing historical pump data comprising historical values of pump inlet pressure over a historical time period; operating the scroll pump to pump the fluid, wherein the operating is done during a recent time period preceded by the historical time period; during the operating, determining (e.g., measuring or calculating) pump inlet pressure to acquire recent pump data comprising recent values of pump inlet pressure over the recent time period; comparing the recent pump data and the historical pump data; and based on the comparing, determining that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required.

According to another implementation, the scroll pump is a scroll pump under assessment, and the providing of the historical pump data comprises at least one of: operating the scroll pump under assessment and measuring the pump inlet pressure to acquire the historical values; accessing a database comprising the historical values of pump inlet pressure over the historical time period, wherein the historical values were acquired by operating one or more scroll pumps other than the scroll pump under assessment.

According to another implementation, the method includes, after the determining that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required, at least one of: shutting down the scroll pump and replacing the first scroll tip seal and/or the second scroll tip seal with a new first scroll tip seal and/or a new second scroll tip seal; producing a user-interpretable output indicating that the tip seal maintenance and/or the further diagnosis is required.

According to another implementation, if it is determined that further diagnosis of the scroll pump is required, a user may be directed or guided to perform certain diagnostic activities, and the pump inlet pressure may continue to be monitored. The diagnostic activities may include testing or evaluating the scroll pump by operating the scroll pump under various operating conditions (e.g., high RPM and low RPM, with and without a gas ballast, with and without a fixed orifice installed for evaluation, etc.). As a result, it may be determined that tip seal replacement is not yet required. As an example, the diagnosis may reveal a problem not relating to tip seal wear. As another example, during or after performing the diagnosis, it may be determined that the pump inlet pressure has come down (or returned) to an acceptable level (e.g., the measured increase in pump inlet pressure was a short-term event that is not attributable to tip seal wear).

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating an average recent inlet pressure value from the recent pump data; calculating or providing an average historical inlet pressure value from the historical pump data; and calculating or providing an average historical inlet pressure value from the historical pump data; and determining that the average recent inlet pressure value exceeds the average historical inlet pressure value by more than a threshold value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating an average recent inlet pressure value from the recent values of a most recent time-slice of the recent time period; calculating or providing an average historical inlet pressure value from the historical values of a historical time-slice that precedes the most recent time-slice; and determining that the average recent inlet pressure value exceeds the average historical inlet pressure value by more than a threshold value.

In an implementation, the threshold value assessed may be a difference between the average recent inlet pressure value and the average historical inlet pressure value. Alternatively or additionally, the threshold value assessed may be a ratio of the average recent inlet pressure value and the average historical inlet pressure value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating a slope value of inlet pressure over time, wherein the slope value is based on values of pump inlet pressure acquired during a set duration of the recent time period; and determining that the slope value exceeds a threshold value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating a first slope value of inlet pressure over time, wherein the first slope value is based on values of pump inlet pressure acquired during a most recent time-slice of the recent time period; calculating a second slope value of inlet pressure over time, wherein the second slope value is based on values of pump inlet pressure acquired during a historical time-slice of the historical time period; and determining that the first slope value exceeds the second slope value by a threshold value.

In an implementation, the threshold value assessed may be a difference between the first slope value and the second slope value. Alternatively or additionally, the threshold value assessed may be a ratio of the first slope value and the second slope value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating a recent time-to-pressure value corresponding to one or more pump-down cycles in the recent time period; calculating or providing an average historical time-to-pressure value from time-to-pressure values corresponding to one or more pump-down cycles in the historical time period; and determining that the recent time-to-pressure value exceeds the average historical time-to-pressure value by a threshold value.

In an implementation, the threshold value assessed may be a difference between the recent time-to-pressure value and the average historical time-to-pressure value. Alternatively or additionally, the threshold value assessed may be a ratio of the recent time-to-pressure value and the average historical time-to-pressure value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating an average recent pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in the recent time period; calculating or providing an average historical pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in the historical time period; and determining that the average recent pressure-at-set-elapsed-time value exceeds the average historical pressure-at-set-elapsed-time value by a threshold value.

In an implementation, the threshold value assessed may be a difference between the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value. Alternatively or additionally, the threshold value assessed may be a ratio of the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating an average recent time-to-pressure value from time-to-pressure values corresponding to pump-down cycles occurring in a recent time-slice of the recent time period; calculating or providing an average historical time-to-pressure value from time-to-pressure values corresponding to pump-down cycles occurring in a historical time-slice of the historical time period; and determining that the average recent time-to-pressure value exceeds the average historical time-to-pressure value by a threshold value.

In an implementation, the threshold value assessed may be a difference between the average recent time-to-pressure value and the average historical time-to-pressure value. Alternatively or additionally, the threshold value assessed may be a ratio of the average recent time-to-pressure value and the average historical time-to-pressure value.

According to another implementation, the determining that the tip seal maintenance and/or the further diagnosis is required includes: calculating an average recent pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a recent time-slice of the recent time period; calculating or providing an average historical pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a historical time-slice of the historical time period; and determining that the average recent pressure-at-set-elapsed-time value exceeds the average historical pressure-at-set-elapsed-time value by a threshold value.

In an implementation, the threshold value assessed may be a difference between the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value. Alternatively or additionally, the threshold value assessed may be a ratio of the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value.

For any of the any of the implementations summarized above or disclosed herein that assess time-slices, the historical (previous) time-slice and the recent (or most recent) time-slice may have the same duration or different durations.

For any of the any of the implementations summarized above or disclosed herein that assess time-slices, the historical (previous) time-slice may be the time-slice that immediately precedes the recent (or most recent) time-slice under assessment. Alternatively, the historical (previous) time-slice may be a time-slice that is farther back in time in the historical time period. For example, the historical (previous) time-slice may be a time-slice that occurred three or four time-slices prior to the recent (or most recent) time-slice.

For any of the any of the implementations summarized above or disclosed herein that assess time-slices, the method may include considering multiple recent time-slices and multiple historical time-slices instead of just a single recent time-slice and a single historical time-slice. In this case, the values of the characteristic of interest (e.g., average inlet pressure, P vs. t slope, time-to-pressure, pressure-at-set-elapsed-time, etc.) taken from the multiple recent time-slices may be aggregated, and the values of the characteristic of interest taken from the multiple historical time-slices may be aggregated. The recent aggregated values may then be compared to the historical aggregated values in accordance with any of the method implementations summarized above or disclosed herein.

According to another implementation relating to the method and/or scroll pump and/or non-transitory computer-readable medium, the method includes performing two or more of the method implementations summarized above or disclosed herein to thereby obtain a plurality of calculated values corresponding to the two or more method implementations performed (e.g., average recent inlet pressure value and average historical inlet pressure value; and/or slope value(s) of inlet pressure over time; and/or (average) recent time-to-pressure value and average historical time-to-pressure value; and/or average recent pressure-at-set-elapsed-time value and average historical pressure-at-set-elapsed-time value, etc.). In this implementation, the determining that the tip seal maintenance and/or the further diagnosis is required may include determining that a threshold value corresponding to at least one of the plurality of calculated values has been exceeded. Alternatively, the determining that the tip seal maintenance and/or the further diagnosis is required may include determining that threshold values respectively corresponding to more than one (e.g., at least two) of the plurality of calculated values have been exceeded. In other words, more than one type of method implementation may be performed to confirm that the tip seal maintenance and/or the further diagnosis is required.

According to another implementation, a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: a pump inlet; a pump outlet; a pumping stage comprising a first scroll and a second scroll nested together, wherein at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to create a moving pocket between the first scroll and the second scroll effective to pump fluid from the pump inlet to the pump outlet; a first scroll tip seal mounted to the first scroll; a second scroll tip seal mounted to the second scroll; a sensor configured to measure pump inlet pressure or to measure an operating parameter from which the pump inlet pressure can be calculated; and a controller. The controller is configured to assess tip seal wear, by controlling or performing an operation that includes: providing historical pump data comprising historical values of pump inlet pressure over a historical time period; operating the scroll pump to pump the fluid, wherein the operating is done during a recent time period preceded by the historical time period; during the operating, determining pump inlet pressure to acquire recent pump data comprising recent values of pump inlet pressure over the recent time period; comparing the recent pump data to the historical pump data; and based on the comparing, determining that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required.

According to another implementation, a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: a pump inlet; a pump outlet; a pumping stage comprising a first scroll and a second scroll nested together, wherein at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to create a moving pocket between the first scroll and the second scroll effective to pump fluid from the pump inlet to the pump outlet; a first scroll tip seal mounted to the first scroll; a second scroll tip seal mounted to the second scroll; a sensor configured to measure pump inlet pressure or to measure an operating parameter from which the pump inlet pressure can be calculated; and a controller. The controller is configured to control or perform one or more of the steps of any of the method implementations summarized above or disclosed herein.

According to another implementation, a non-transitory computer-readable medium includes instructions stored thereon, that when executed on a processor, control or perform one or more of the steps of any of the method implementations summarized above or disclosed herein.

Other devices, apparatus, systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.

FIG. 1 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time to illustrate typical patterns for the three common types of applications of a scroll pump.

FIG. 2 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time to illustrate the typical pattern of tip seal wear-out for a scroll pump operating at zero gas load or constant gas load.

FIG. 3 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time while operating a scroll pump in accordance with repetitive pump-down cycles of constant duration.

FIG. 4 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time while operating a scroll pump in accordance with repetitive pump-down cycles, and with the duration of the pump-down cycles being controlled by the time of reaching a target pump inlet pressure.

FIG. 5 is a cross-sectional elevation view of an example of a scroll pump (assembly) in which the subject matter disclosed herein may be implemented.

FIG. 6 is a cross-sectional elevation view of an example of a pump head for a scroll pump in which the subject matter disclosed herein may be implemented.

FIG. 7 is a cross-sectional perspective view of an orbiting scroll included with the pump head illustrated in FIG. 6.

FIG. 8 is a cross-sectional plan view (in the transverse plane) of a pumping stage of the pump head illustrated in FIG. 6.

FIG. 9 is a close-up view of a region of two pumping stages of the pump head illustrated in FIG. 6.

FIG. 10 is a schematic view of an example of a vacuum pumping system according to an implementation of the present disclosure.

FIG. 11 is a schematic view of a system controller for a scroll pump and/or vacuum pumping system according to an implementation of the present disclosure.

FIG. 12 is a flow diagram illustrating an example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 13 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 14 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 15 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 16 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 17 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 18 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 19 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

FIG. 20 is a graph plotting pump inlet pressure (specifically the logarithm thereof) versus time illustrating another example of a method for assessing scroll pump tip seal wear according to an implementation of the present disclosure.

The illustrations in all of the drawing figures are considered to be schematic, unless specifically indicated otherwise.

DETAILED DESCRIPTION

In this disclosure, all “implementations,” “aspects,” “examples,” and “embodiments” described are considered to be non-limiting and non-exclusive. Accordingly, the fact that a specific “implementation,” “aspect,” “example,” or “embodiment” is explicitly described herein does not exclude other “implementations,” “aspects,” “examples,” and “embodiments” from the scope of the present disclosure even if not explicitly described. In this disclosure, the terms “implementations,” “aspect,” “example,” and “embodiment” are used interchangeably, i.e., are considered to have interchangeable meanings.

In this disclosure, the term “substantially,” “approximately,” or “about,” when modifying a specified numerical value, may be taken to encompass a range of values that include +/−10% of such numerical value, unless specifically indicated otherwise.

FIG. 5 is a cross-sectional elevation view of an example of a scroll pump (assembly) 500 in which the subject matter disclosed herein may be implemented. The scroll pump 500 may be configured for use as a vacuum pump or as a compressor, as appreciated by persons skilled in the art. The type of working fluid pumped by the scroll pump 500 depends on the application for which the scroll pump 500 is utilized. The working fluid is often a gas (or mixture of gases) such as, for example, air, oxygen, nitrogen, a noble gas (e.g., helium, argon, etc.), a gas-phase compound (e.g., carbon dioxide, a refrigerant, etc.), a gas utilized in a chemical, manufacturing, or analytical process, or in applications requiring compressed air, etc. Alternatively, the working fluid may be a liquid such as may be utilized in a chemical, manufacturing, or analytical process, or a refrigerant in cooling applications, etc. The structure and operation of scroll pumps are generally understood by persons skilled in the art, and thus the scroll pump 500 and certain components thereof are described only briefly herein to provide a context for the presently disclosed subject matter.

The scroll pump 500 includes a pump head 502 powered by a motor 504. Typically, the motor 504 is an electric motor that includes a motor rotor (not shown) driven to rotate relative to a motor stator (not shown) by a magnetic field established between the motor rotor and motor stator by permanent magnets and/or electromagnets provided with the motor rotor and motor stator, as appreciated by persons skilled in the art. The motor rotor is coupled to a motor (output) shaft 508 that thus rotates with the motor rotor. The motor shaft 508 is coupled to a crankshaft 512 by an appropriate shaft coupling 516 such that the crankshaft 512 is driven to rotate by the motor rotor via the motor shaft 508 and shaft coupling 516. The shaft coupling 516 may be a mechanical coupling (e.g., shaft joint, spider coupling, etc.) or a non-contact type of coupling such as an axially-or radially-oriented magnetic coupling, as appreciated by persons skilled in the art. Alternatively, the pump head 502 and motor 504 are directly coupled by a single drive shaft instead of utilizing a separate motor shaft 508, crankshaft 512 and intermediate shaft coupling 516. The motor shaft 508 and at least a main portion of the crankshaft 512 rotate concentrically or coincidently about a central drive axis D.

The pump head 502 includes a pump frame 520, which may be a single-part construction or a multi-part construction in which two or more separate frame parts may be assembled to each other and disassembled from each other (e.g., for performing maintenance on the scroll pump 500). The pump frame 520 may be configured to serve as a pump housing that encloses various components of the pump head 502, and/or as a structural support to which various components are attached or with which various components are integral. The pump head 502 further includes one or more pumping elements configured to define one or more pumping (or compression) stages 524. At least one of the pumping elements is coupled to and driven to move by the crankshaft 512. In the implementations described herein, the pumping elements are scrolls as described in more detail below. The pump head 502 further includes a pump inlet 528 and an inlet conduit 532 (e.g., one or more passages, pipes, tubes, chambers, manifolds, plenums, headers, etc.) configured to direct a flow of incoming (aspirated) working fluid (the fluid being pumped) from the pump inlet 528 to the pumping stage(s) 524. The pump head 502 further includes a pump outlet 536 and an outlet conduit 540 (e.g., one or more passages, pipes, tubes, chambers, manifolds, plenums, headers, etc.) configured to direct a flow of outgoing (discharged) working fluid from the pumping stage(s) 524 to the pump outlet 536. Accordingly, the pump head 502 (particularly the pumping stage(s) 524) is configured to transport (or displace by pumping action) the working fluid from the pump inlet 528, through the inlet conduit 532, through the pumping stage(s) 524 and through the outlet conduit 540, and to the pump outlet 536, as indicated by an arrow F in FIG. 5. The inlet side of the pumping stage(s) 524 is the low-pressure (or vacuum) side and the outlet side of the pumping stage(s) 524 is the high-pressure side (the term “high” being relative to the term “low”).

The pump inlet 528 and/or the pump outlet 536 may include fittings as needed for fluidly connecting the pump head 502 to components (e.g., conduits, chambers, etc.) external to the scroll pump 500. For example, in the case of a vacuum pump, the pump inlet 528 may be configured to be fluidly coupled to a vacuum chamber (i.e., a chamber or enclosed space to be evacuated; see FIG. 10) and, depending on the application, the pump outlet 536 may discharge compressed fluid directly to the ambient or may be configured to be fluidly coupled to an appropriate receptacle for containing the discharged fluid. In the case of a compressor, the pump inlet 528 may be configured to be fluidly coupled to an upstream part of a system that circulates the working fluid (e.g., a heat exchanger or refrigeration system) or to intake ambient air (e.g., in the case of an air compressor), and the pump outlet 536 may be configured to be fluidly coupled to a device, tool or system that utilizes compressed fluid (i.e., is a consumer of compressed fluid, such as an air-powered tool). Such a downstream entity that receives compressed fluid from the scroll pump 500 may be referred to generally as a “destination” fluidly communicating with the pump outlet 136.

For purposes of reference and description, terms such as “axial” and “axially” are taken relative to the drive axis D. The drive axis D may be extended in either direction and considered to be part of (or coincident with) an overall longitudinal pump axis of the scroll pump 500. For example, an “axial distance” between any two components of the scroll pump 500 is a distance measurable along the (extended) drive axis D in either direction (from left to right, or right to left, from the perspective of FIG. 5). The drive axis D/pump axis is horizontal from the perspective of FIG. 5. In addition, terms such as “radial” and “transverse” refer to directions orthogonal to the axis D/pump axis, including the vertical direction from the perspective of FIG. 5. In the present context, the terms “horizontal” and “vertical” are relative to each other. The perspective of FIG. 5 is but one example; that is, the scroll pump 500 is not limited to the orientation shown in FIGS. 5-9. In addition, the scroll pump 500 is considered to have a front side 544 and a rear side 548. From the perspective of FIG. 5, the front side 544 corresponds to the left side and the rear side 548 corresponds to the right side of the scroll pump 500. Along the axial direction, the pump head 502 is nearer to the front side 544 than the motor 504, and the motor 504 is nearer to the rear side 548 than the pump head 502. Further, the pump head 502 is considered to have an outboard side 552 and an inboard side 556. Along the axial direction, the outboard side 552 is nearer to the front side 544 than the inboard side 556, and the inboard side 556 is nearer to the motor 504 than the outboard side 552. Along the axial direction, the outboard side 552 is nearer to the ambient (the space or environment external to the scroll pump 500) than the inboard side 556. In other words, the inboard side 556 is located farther into the interior of the pump head 502 than the outboard side 552. Correspondingly, any of the individual components (e.g., the pumping stage 524) of the pump head 502 likewise may be considered to have an outboard side and an inboard side.

The scroll pump 500 may further include an outer cowling 564 that covers all or a portion of the pump head 502. The motor 504 may also be enclosed in the cowling 164 or in a motor housing (not shown) distinct from the cowling 564. The cowling 564 and/or motor housing may enclose electrical components external to the motor 504 (e.g., circuitry, wiring/cables, electrical interconnects, other electrical hardware, etc.). An electrical component may be configured to control motor speed, one example being an inverter. The scroll pump 500 may further include a suitable base or platform 568 configured to support the weight of the scroll pump 500 in a stable manner as the scroll pump 500 rests on or is mounted to an underlying surface such as a floor, table, bench, etc.

The scroll pump 500 may further include one or more cooling fans 572 for directing cooling air into thermal contact with the pump head 502 or additionally the motor 504 to carry dissipated heat away from the scroll pump 500. In the present implementation, a cooling fan 572 is positioned in the pump frame 520 axially between the inboard side of the pumping stage(s) 524 and the motor 504. In this case, the cooling fan 572 may be mounted to and thereby powered by the crankshaft 512 as illustrated. The cooling fan 572 may draw in ambient air from, for example, the rear or outboard side of the pump head 502, such as though one or more openings (vents) formed in the pump frame 520, direct the drawn in ambient air along one or more air flow paths through the interior of the pump frame 520 (including around and in thermal contact with the pumping stage(s) 524), and discharge the now heat-laden ambient air out from one or more openings (vents) formed in the cowling 564 at the front or inboard side of the pump head 502. FIG. 5 depicts an example of a few air flow paths by arrows A.

FIG. 6 is a cross-sectional elevation view of an example of a pump head 602 according to an implementation of the present disclosure. The pump head 602 may be utilized, for example, as the pump head 502 of the scroll pump 500 described above and illustrated in FIG. 5.

Generally, the pump head 602 may include a stationary pump frame and/or pump housing (not shown) that encloses and/or supports various components of the pump head 602. For example, various components of the pump head 602 may be integrated with or attached to a pump frame or housing. In the present implementation, the pump head 602 is a multi-stage pump head. Specifically, the pump head 602 is a two-stage pump head and thus includes a first (or outboard, or upstream) pumping stage 624A and a second (or inboard, or downstream) pumping stage 624B fluidly communicating in series (with respect to the fluid flow path F, FIG. 5) with the first pumping stage 624A. The first pumping stage 624A receives the (lower-pressure) working fluid from the pump inlet 528 (FIG. 5), (at least slightly) compresses the working fluid, and outputs the compressed working fluid to the second pumping stage 624B. The second pumping stage 624B further compresses the working fluid and discharges the (now even higher-pressure) working fluid to the pump outlet 536 (FIG. 5). As shown, the total internal volume and volumetric displacement rate of one pumping stage (e.g., first pumping stage 624A) may be different from those of the other pumping stage (e.g., second pumping stage 624B).

Alternatively, the pump head 602 may be configured such that the inboard pumping stage is the first pumping stage and the outboard pumping stage is the second pumping stage. Alternatively, the pump head 602 may provide more than two pumping stages and/or two or more pumping stages operating in parallel. As another alternative, the pump head 602 may be a single-stage pump head.

Each pumping stage 224A and 224B provided includes a first scroll and a second scroll nested together in a manner described below. One or both of these scrolls orbits about the drive axis D relative to the other scroll as described further below. In the examples illustrated herein, the first scroll is configured to orbit while the second scroll remains stationary (i.e., as a pump stator). In this case, the first scroll may be referred to as an orbiting scroll and the second scroll may be referred to as a fixed scroll. Alternatively, one or both of the pumping stages 224A and 224B may have a co-rotating configuration in which both scrolls are configured to orbit about the drive axis D relative to each other. In this case, the first scroll may be referred to as a drive scroll and the second scroll may be referred to as a driven scroll, as its orbiting motion is driven by the orbiting motion of the first (drive) scroll.

In the implementation illustrated in FIG. 6, the pump head 602 includes an orbiting (first) scroll 680 axially interposed between a fixed (second) outboard scroll 684A and a fixed (third) inboard scroll 684B. The fixed outboard scroll 684A and the outboard side of the orbiting scroll 680 cooperatively define the first pumping stage 624A, and the fixed inboard scroll 684B and the inboard side of the orbiting scroll 680 cooperatively define the second pumping stage 624B. During operation of the pump head 602, the orbiting scroll 680 eccentrically orbits in a circular path around the drive axis D at an offs et or radial distance r (in the transverse plane orthogonal to the drive axis D) from the drive axis D, as described further below.

The orbiting scroll 680 includes an orbiting scroll plate 688 oriented in the transverse plane, at least one orbiting outboard (first) scroll blade 692A extending (or projecting) axially from the outboard side of the orbiting scroll plate 688 toward the fixed outboard scroll 684A, and at least one orbiting inboard (second) scroll blade 692B extending (or projecting) axially from the inboard side of the orbiting scroll plate 688 toward the fixed inboard scroll 684B. The fixed outboard scroll 684A includes a transversely-oriented fixed outboard scroll plate 696A and at least one fixed outboard scroll blade 698A extending (or projecting) axially toward the outboard side of the orbiting scroll plate 688. The fixed inboard scroll 684B includes a transversely-oriented fixed inboard scroll plate 696B and at least one fixed inboard scroll blade 698B extending (or projecting) axially toward the inboard side of the orbiting scroll plate 688.

The fixed inboard scroll 684B may be removably attached to or integral with the above-noted pump frame or housing. The fixed outboard scroll 684A may be removably attached to the fixed inboard scroll 684B (or alternatively to another stationary structure such as the pump frame) by an appropriate fastening device (e.g., a pattern of bolts or screws 276 as illustrated, etc.).

The orbiting outboard scroll blade 692A, the orbiting inboard scroll blade 692B, the fixed outboard scroll blade 698A, and the fixed inboard scroll blade 698B are each spiral-shaped (each runs along a spiral path, which may be Archimedean, involute, etc.) in the transverse plane. The cross-sectional view of FIG. 6 shows several (e.g., four) turns or revolutions taken by the scroll blades 692A, 692B, 698A and 698B, along their respective spiral paths. As shown, the orbiting outboard scroll blade 692A is juxtaposed with the fixed outboard scroll blade 698A in the radial direction (orthogonal to the drive axis D), such that the orbiting outboard scroll blade 692A and the fixed outboard scroll blade 698A are nested (or interleaved, interdigitated, intermeshed, etc.) together with a predetermined relative angular positioning. Likewise, the orbiting inboard scroll blade 692B is juxtaposed with the fixed inboard scroll blade 698B in the radial direction, such that the orbiting inboard scroll blade 692B and the fixed inboard scroll blade 698B are nested together with a predetermined relative angular positioning. By this configuration, as the orbiting scroll 680 orbits relative to the fixed outboard scroll 684A and the fixed inboard scroll 684B, one or more variable-volume pockets are defined in the first pumping stage 624A by (and between) the nested orbiting outboard scroll blade 692A and fixed outboard scroll blade 698A, and one or more variable-volume pockets are defined in the second pumping stage 624B by (and between) the nested orbiting inboard scroll blade 692B and fixed inboard scroll blade 698B.

As an example, FIG. 7 is a cross-sectional perspective view of the orbiting scroll 680 in which about half of the orbiting scroll 680 is illustrated. FIG. 7 shows the multi-revolution, spiral shapes of the orbiting outboard scroll blade 692A and orbiting inboard scroll blade 692B. The spiral shapes of the fixed outboard scroll blade 698A and the fixed inboard scroll blade 698B (FIG. 6) may be similar.

As another example, FIG. 8 is a cross-sectional plan view (in the transverse plane) of the second pumping stage 624B. FIG. 8 illustrates the nested relation between the orbiting inboard scroll blade 692B and the fixed inboard scroll blade 698B, and the development of crescent-shaped, moving, variable-volume pockets P between adjacent sections of the orbiting inboard scroll blade 692B and the fixed inboard scroll blade 698B (see also FIG. 9). The second pumping stage 624B includes one or more pumping stage inlet ports located at or near the outer periphery, and one or more pumping stage outlet ports located at or near the center. Generally, the working fluid enters at least one inlet port, is compressed and displaced radially inwardly toward the center, and then is discharged from at least one outlet port. For example, as the orbiting inboard scroll blade 692B orbits, the trailing end of a given (or first) pocket P opens into fluid communication with an inlet port and takes in a quantity of the incoming working fluid. As the orbiting inboard scroll blade 692B continues to orbit, both the leading end and the trailing end of the pocket P may become substantially closed off, i.e., leaving only a small clearance between adjacent points of the orbiting inboard scroll blade 692B and the fixed inboard scroll blade 698B at the respective leading end and trailing end. In addition, the volume of the pocket P decreases, thereby (at least slightly) compressing the working fluid trapped in the pocket P. As the orbiting inboard scroll blade 692B continues to orbit further, the leading end of the pocket P opens into fluid communication with an outlet port and the compressed working fluid is discharged from the pocket P and through the outlet port. One or more additional pockets P may operate in same manner at least partially simultaneously with the first pocket P.

In the present implementation, the first pumping stage 624A includes one or more pumping stage inlet ports located at or near the center, and one or more pumping stage outlet ports located at or near the outer periphery. In this configuration, the working fluid enters at least one inlet port, is compressed and displaced radially outwardly toward the outer periphery, and then is discharged from at least one outlet port. This pumping action is effected by moving pockets in a manner analogous to the second pumping stage 624B just described. The working fluid is then transferred to at least one inlet port of the second pumping stage 624B via an interconnecting fluid passage.

In some implementations, at least one of the pumping stages 624A or 624B includes more than one distinct pair of nested scroll blades. An example of a pumping stage having three pairs of nested scroll blades is described in above-referenced U.S. Pat. No. 5,855,473.

As shown in FIG. 6, the pump head 602 includes a crankshaft 612, which may correspond to the crankshaft 512 described above and illustrated in FIG. 5. The crankshaft 612 includes a main shaft 606 (portion or section) and an eccentric shaft (portion or section) or crank 610 integral with or attached to the main shaft 606. The main shaft 606 extends in the outboard direction from the motor side (from right to left in FIG. 6) into a central bore 614 of the fixed inboard scroll 684B. The main shaft 606 rotates directly on (coaxial or coincidently with) the drive axis D, which rotation is driven by the motor 504 (FIG. 5). One or more bearings 618 are configured to support the rotation of the main shaft 606 and/or bear thrust forces generated during operation. The crank 610 extends in the outboard direction from the main shaft 606 into the central (orbiting scroll) bore of an orbiting scroll hub 622 of the orbiting scroll 680. The central axis of the crank 610 (designated as crank axis C in FIG. 6A) is radially offset from the central axis of the main shaft 606 (drive axis D) by the above-noted radial distance r and thus orbits in a circular path of radius r around the drive axis D as the main shaft 606 rotates on the drive axis D. The orbiting scroll 680 is coupled to the crank 610 via one or more bearings 626 and thus orbits with the crank 610. The bearings 626 are configured to support the orbiting of the crank 610 and orbiting scroll 680 and/or bear thrust forces generated during operation.

The pump head 602 is configured to constrain the motion of the orbiting scroll 680 to the orbiting motion only. That is, the pump head 602 is configured to prevent the orbiting scroll 680 from rotating about its own central axis (i.e., the crank axis C). For this purpose, the scroll pump 500 may include an appropriate anti-rotation device (e.g., metal bellows, Oldham coupling, eccentrically positioned synchronization cranks or idler shafts, etc., not shown) interfaced with the orbiting scroll 680 as appreciated by persons skilled in the art.

In the present implementation, the pump head 602 may further include an axial end cap or cover 674 positioned at the outermost end (on the outboard side) of the crank 610. The end cap 674 may be removably mounted at least partially inside the orbiting scroll hub 622 and secured by an appropriate retainer 678 such as a snap ring, C-clip or the like that expands into an annular inside groove of the orbiting scroll hub 622.

FIG. 9 is a close-up view of a region of the pumping stages 624A and 624B illustrated in FIG. 6A. As shown, small axial gaps g exist between the blade tips (free ends) of each scroll blade 692A, 692B, 698A and 698B and the surfaces of the scroll plates 688, 696A and 696B that are immediately adjacent to and facing those blade tips. Specifically, an axial gap g exists between the tip of the orbiting outboard scroll blade 692A and the fixed outboard scroll plate 696A, another axial gap g exists between the tip of the fixed outboard scroll blade 698A and the outboard side of the orbiting scroll plate 688, another axial gap g exists between the tip of the orbiting inboard scroll blade 692B and the fixed inboard scroll plate 696B, and an another axial gap g exists between the tip of the fixed inboard scroll blade 698B and the inboard side of the orbiting scroll plate 688. The axial gaps g create partially or substantially fluid-sealed interfaces that allow the development of the above-noted moving, variable-volume pockets P for trapping, compressing and transporting the working fluid without constraining the orbital motion of the orbiting scroll 680.

In the present implementation, the axial gaps g are at least partially occupied or filled by dynamic tip seals 682. The blade tip of each scroll blade 692A, 692B, 698A and 698B has a groove 686 (see also FIG. 3) in which a tip seal 682 is mounted, such that each groove 686 and corresponding tip seal 682 (orbiting outboard tip seal, orbiting inboard tip seal, fixed outboard tip seal, and fixed inboard tip seal) run along the same spiral path as its corresponding scroll blade 692A, 692B, 698A and 698B. The above-noted axial gap g may be specified as being the axial distance between the bottom of the groove 686 (instead of the blade tip) and the correspondingly adjacent scroll plate 688, 696A and 696B. As one example, the axial gap g may be on the order of a few (e.g., less than 10) thousandths of an inch (e.g., in a range from 0.001″ to 0.002″, or about 0.025 mm to about 0.051 mm). The tip seals 682 may each have a one-piece construction composed of a relatively rigid polymer with low-friction characteristics such as, for example, polytetrafluoroethylene (PTFE), ultra-high-molecular-weight polyethylene (UHMW-PE), etc., or an elastomeric polymer such as, for example, a natural or synthetic rubber (e.g., a closed-cell foam rubber). Alternatively, the tip seals 682 may each have a two-piece construction that includes an elastomeric (springy) layer resting on the bottom of the groove 686 and a wear-resistant layer (e.g., PTFE) disposed on the elastomeric layer and extending out from the groove 686.

The tip seals 682 may enhance the sealing interfaces between the orbiting scroll 680 and the fixed scrolls 684A and 684B. During operation of the pump head 602 and particularly during the orbital motion of the orbiting scroll 680, the tip seals 682 prevent direct contact between the blade tips of the scroll blades 692A, 692B, 698A and 698B and the correspondingly adjacent scroll plates 688, 696A and 696B. Due to exposure to friction and heat, the tip seals 682 eventually wear down with pump operation over time, which degrades the sealing effectiveness of the tip seals 682 and thus the pumping performance of the pumping stages 624A and 624B (e.g., the ability to generate and maintain vacuum). Thus, the tip seals 682 have a limited service life and periodically need to be replaced as part of a regular maintenance procedure.

The size (axial distances) of the axial gaps g affects the sealing effectiveness of the tip seals 682 and thus the pumping performance. The axial gap size depends on the axial position of the orbiting scroll 680 relative to the fixed scrolls 684A and 684B.

In the present implementation, the pump head 602 includes an adjusting nut 690 configured to control (adjust or set) the axial position of the orbiting scroll 680 and hence the axial gap size. The adjusting nut 690 is axially adjustable relative to the crank 610. For this purpose, the adjusting nut 690 may be directly engaged with the crank 610. For example, in the present implementation, the adjusting nut 690 is threaded (screwed) onto the crank 610 such that the adjusting nut 690 is positioned axially between the end cap 674 and the outermost bearing 626 that is at least partially responsible for coupling the crank 610 and the orbiting scroll 680.

An example of partially disassembling the pump head 602 will now be described with reference being made primarily to FIG. 6. First, any components covering the outboard side of the pump head 602 (e.g., cowling 564 shown in FIG. 5, if provided, and any other covers, caps, etc.) are removed. Next, the fixed outboard scroll 684A is detached (e.g., unfastened) and removed from the fixed inboard scroll 684B (or from another stationary structure of the pump head 602, depending on the implementation). At this time or later, the tip seal 682 of the fixed outboard scroll 684A may be removed and replaced with a new tip seal if needed, and/or the fixed outboard scroll 684A may be otherwise serviced (e.g., cleaned, repaired, relubricated, etc.) or replaced. For example, before mounting a new tip seal, the tip seal groove 686 of the fixed outboard scroll 684A may be cleaned. The end cap 674 is then removed, which may involve removing the retainer 678 (e.g., by utilizing an appropriate tool such as snap-ring pliers). The orbiting scroll 680 is then removed. Depending on the implementation, the outermost bearing 626 may need to be removed before removing the entire orbiting scroll 680. Depending on the implementation, a tool may or may not be needed to assist in removing the outermost bearing 626, or other bearings, or other annular components surrounding the crank 610. At this time or later, the outboard-side and inboard-side tip seals 682 of the orbiting scroll 680 may be removed and replaced with new tip seals if needed, and/or the orbiting scroll 680 may be otherwise serviced (e.g., cleaned, repaired, etc.) or replaced. For example, before mounting a new tip seal, the tip seal grooves 686 of the orbiting scroll 680 may be cleaned. In addition, any components located inside the orbiting scroll hub 622 and/or on or around the crank 610 (e.g., bearings 626, spacers, sleeves, washers, springs, shaft seals, etc.) may be serviced or replaced if needed.

The removal of the orbiting scroll 680 not only provides access to the inboard-side of the orbiting scroll 680, but also provides access to the fixed inboard scroll 684B from the outboard side of the pump head 602. The removal of the orbiting scroll 680 exposes the fixed inboard scroll 684B to the outboard side of the pump head 602. Hence, access to the fixed inboard scroll 684B does not require the fixed inboard scroll 684B to be detached and removed from the pump frame or housing, and such access also does not require the fixed inboard scroll 684B or any other any other component on the inboard side of the pump head 602 to be detached and/or removed from the crankshaft 612, shaft coupling 516 (FIG. 5), motor shaft 508, motor 504, or the like. With the orbiting scroll 680 removed, the tip seal 682 of the fixed inboard scroll 684B is then removed and replaced with a new tip seal, and the tip seal groove 686 of the fixed inboard scroll 684B may be cleaned, if needed. After maintenance is completed, reassembly of the pump head 602 may entail essentially the reverse of the foregoing steps of disassembly.

As an example, a scroll pump such as disclosed herein may operate at a pumping speed in a range from 30 L/min to 1200 L/min. As an example, a scroll pump such as disclosed herein may operate at an inlet pressure in a range from 1 atmosphere (735.6 Torr) to 1×10⁻⁴ Torr. As an example, a scroll pump such as disclosed herein may generate an ultimate vacuum level in a range from 2 Torr to 5×10⁻⁴ Torr.

FIG. 10 is a schematic view of an example of a vacuum pumping system 1000 according to an implementation of the present disclosure. The vacuum pumping system 1000 includes a scroll pump 500 with a pump inlet 528, a pump outlet 536, a pump head 502 or 602, and a motor 504 such as described above and illustrated in FIGS. 5-9. In the present implementation, the pump inlet 528 is in fluid communication with a vacuum chamber 1004. Generally, the vacuum chamber 1004 may be any chamber (or enclosed space) to be evacuated by operation of the scroll pump 500. The vacuum chamber 1004 may be a part of any apparatus 1008 (or device, instrument, system, etc.) that requires the pressure of an internal volume or region to be pumped down to and maintained at a predetermined vacuum level. Examples of the apparatus 1008 include, but are not limited to, a gas leak detector, mass spectrometer, ion mobility spectrometer, electron microscope, flywheel, etc.

Alternatively, the scroll pump 500 may be a compressor. In this case, the pump outlet 536 may be placed in fluid communication with a downstream destination, as described above.

The vacuum pumping system 1000 may include an inlet pressure sensor 1012 positioned in operative communication with the inlet line of the scroll pump 500 upstream of the pumping stage(s) of the pump head 502/602, at or near the pump inlet 528, for measuring (or monitoring) the inlet pressure of the scroll pump 500 during operation thereof. The vacuum pumping system 1000 may also include an outlet pressure sensor 1016 positioned in operative communication with the outlet line of the scroll pump 500 downstream of the pumping stage(s) of the pump head 502/602, at or near the pump outlet 536, for measuring (or monitoring) the outlet pressure of the scroll pump 500 during operation thereof. Measurement of the inlet pressure or additionally the outlet pressure may be done on a continuous basis or intermittently (e.g., at predetermined time intervals). The scroll pump 500 is configured to operate at different inlet pressures, or in different ranges of inlet pressure (or different inlet pressure regimes, or additionally different outlet pressure regimes), depending on the implementation. In some implementations, the scroll pump 500 may be considered as including the inlet pressure sensor 1012 and the outlet pressure sensor 1016.

The inlet pressure sensor 1012 measures pump inlet pressure directly. Alternatively or additionally, the scroll pump 500 may include one or more sensors configured to measure an operating parameter from which the pump inlet pressure can be calculated or derived. Examples include, but are not limited to, an electrical current sensor 1014 and a voltage sensor 1018, one or both of which may be provided as part of the drive circuitry of the motor 504. At a given motor speed, there is a known relationship between the current drawn by the motor 504 and the pump inlet pressure. At a given motor speed, there is also a known relationship between the power drawn by the motor 504 and the pump inlet pressure. Thus, the pump inlet pressure may be calculated from the measurement signals outputted from the current sensor 1014 and/or voltage sensor 1018 to the controller 1100 described below.

The vacuum pumping system 1000 also includes a run time meter 1020 configured to measure (or log) the cumulative time of operation of the scroll pump 500. For example, the run time meter 1020 may be positioned in operative communication with the motor 504 and log the amount of time the motor 504 is operating. The vacuum pumping system 1000 may also include a pump speed sensor 1024 (e.g., an encoder, tachometer, etc.) configured to measure (or monitor) the rotational speed (e.g., in revolutions per minute, RPM) of the scroll pump 500, for example, through operative communication with a rotating component such as the orbiting scroll 680 (FIG. 6), the motor shaft 508 or the crankshaft 512 (FIG. 5). In some implementations, the pump speed sensor 1024 may serve as a run time meter, in which case the separate run time meter 1020 may not be needed or, alternatively, the operations of both the run time meter 1020 and the pump speed sensor 1024 may be coordinated to properly log the run time (time of operation) of the scroll pump 500. The run time meter 1020 and/or the pump speed sensor 1024 may be integrated with the motor controller or other electronics provided at the motor 504. The vacuum pumping system 1000 may also include one or more temperature sensors 1028 located at one or more positions in the scroll pump 500 to measure (or monitor) temperature at one or more regions of the scroll pump 500.

The vacuum pumping system 1000 further includes a system controller (or controller, or computing device) 1100. The controller 1100 may schematically represent one or more modules (or units, components, etc.) configured (or programmed) for controlling, monitoring and/or timing various functional aspects of the vacuum pumping system 1000 including, for example, the operations of components of (or communicating with) the scroll pump 500. For all such purposes, the controller 1100 may be in wired or wireless communication with one or more of the components of the vacuum pumping system 1000, as depicted by dashed lines in FIG. 10, and may include any suitable combination of hardware, firmware, software, etc., including one or more electronics-based processors and memories, as appreciated by persons skilled in the art. For example, the controller 1100 may include a non-transitory (or tangible) computer-readable medium that includes non-transitory instructions for performing any of the methods disclosed herein. A more detailed example of the controller 1100 is described below with reference to FIG. 11.

As one example, the controller 1100 may control the pump speed, and thus pump inlet and outlet pressures, by sending control signals to the motor 504 (or motor electronics) to control the motor 504 and thus the speed of the drive shaft (e.g., the motor shaft 508 and crankshaft illustrated in FIG. 5). In an implementation, the controller 1100 is capable of operating the scroll pump 500 in different operational modes (e.g., the above-described no-gas load, constant-gas load, cyclical pump-downs, etc.), which may be selected automatically or by the user, according to the specific application to which the scroll pump 500 is utilized. All or part of the controller 1100, as well as the run time meter 1020 and/or the pump speed sensor 1024, may be located directly at the scroll pump 500, such as in an electronics box or as part of an inverter drive that supplies power to the motor 504.

In an implementation, during operation of the scroll pump 500, the controller 1100 is configured to receive measurement signals from the inlet pressure sensor 1012, which may be done continuously or during certain time periods of predetermined lengths and at predetermined intervals. Alternatively or additionally, the controller 1100 utilizes measurements made by the current sensor 1014 and/or voltage sensor 1018 to calculate inlet pressure values, as described above. In an implementation, the controller 1100 is configured to compare these current or recent inlet pressure data with historical inlet pressure data, which may be stored, for example, in a memory (e.g., as a database structure) internal or external to the controller 1100. By this comparison, the controller 1100 is configured to determine whether the tip seals 982 of the scroll pump 500 should be replaced, in accordance with any of the methods described herein. If the controller 1100 positively determines that tip seals 982 (i.e., one or more of the orbiting scroll tip seal(s) 982 and/or the fixed scroll tip seal(s) 982) are worn, the controller 1100 may then produce a user-interpretable output of any appropriate type to the user such as, for example, an audible alarm, a visual alarm, a wired or wireless communication (e.g., email, text message, etc.), etc., or a combination of two or more different types of alarms or communications, as appreciated by persons skilled in the art.

Alternatively or additionally, in response to the positive determination that tip seals 982 are wearing out, the controller 1100 may produce a user-interpretable output indicating to the user that further diagnosis of the scroll pump 500 is required. For example, the controller 1100 may send a communication to the user's computer or smart phone that directs the user to carry out (or guides the user in carrying out) certain diagnostic activities on the scroll pump 500. For example, the user may be directed to evaluate (e.g., compare) pump inlet pressure values at high and low RPM settings while operating the scroll pump 500, and/or while operating the scroll pump 500 with a gas ballast for a prescribed period of time (e.g., 24 hours) and subsequently without the gas ballast for a prescribed period of time (e.g., 4 hours), and/or after installing a fixed orifice to the scroll pump 500 for evaluation, etc. As part of the further diagnosis, the controller 1100 may determine that the pump inlet pressure has come down to an acceptable level of vacuum. In this case, the controller 1100 may inform the user that tip seal replacement is not required at that present time. For carrying out the foregoing diagnostic activities, the controller 1100 may execute an appropriately configured computer program that may be located (e.g., stored on a tangible medium) on or at, for example, the scroll pump 500 or the user's computing device (PC workstation, laptop, tablet computer, smartphone, etc.).

FIG. 11 is a schematic view of a more detailed example of a system controller 1100 configured to control a vacuum pumping system (e.g., 1000), in particular the scroll pump 500 and its sensing/measuring/logging devices, according to an implementation of the present disclosure. All or part of the controller 1100 may correspond to the controller 1100 described above in conjunction with FIG. 10. The controller 1100 may schematically represent one or more modules, control units, components, or the like configured for controlling, monitoring, analyzing and/or timing the operations of various devices or components of the vacuum pumping system 1000, as well as controlling or executing one or more steps of any of the methods disclosed herein. In addition to the various controllable devices or components described above in conjunction with FIG. 10, other devices may include, but are not limited to, electrical power (voltage) sources, timing controllers, clocks, frequency/waveform generators, processors, logic circuits, memories, databases, etc. One or more modules of the controller 1100 may be, or be embodied in, one or more devices located outside or separate from the vacuum pumping system 1000, for example, a computer workstation, desktop computer, laptop computer, portable computer, tablet computer, handheld computer, mobile computing device, personal digital assistant (PDA), smartphone, remote server, etc. One or more modules of the controller 1100 may communicate with one or more other modules via one or more busses or other types of communication lines or wireless links, as appreciated by persons skilled in the art.

In the illustrated implementation, the controller 1100 includes one or more electronics-based processors 1102, which may be representative of a main electronic processor providing overall control, and one or more electronic processors configured for dedicated control operations or specific signal processing tasks (e.g., a graphics processing unit or GPU, a digital signal processor or DSP, an application-specific integrated circuit or ASIC, a field-programmable gate array or FPGA, etc.). The controller 1100 also includes one or more memories 1104 (volatile and/or non-volatile types, e.g., RAM and/or ROM) for storing data and/or software. Stored data may be organized, for example, in one or more databases or look-up tables. The controller 1100 may also include one or more device drivers 1106 for controlling one or more types of user interface devices and providing an interface between the user interface devices and components of the controller 1100 communicating with the user interface devices. Such user interface devices may include user input devices 1108 (e.g., keyboard, keypad, touch screen, mouse, joystick, trackball, and the like) and user output devices 1110 (e.g., display screen, printer, visual indicators or alerts, audible indicators or alerts, and the like). In various implementations, the controller 1100 may be considered as including one or more of the user input devices 1108 and/or user output devices 1110, or at least as communicating with them.

In some implementations, the controller 1100 may also include one or more types of computer programs or software contained in memory and/or on one or more types of non-transitory (or tangible) computer-readable media. One or more devices of the controller 1100 may be configured to receive and read (and optionally write to) the computer-readable media. The computer programs or software may contain non-transitory instructions (e.g., logic instructions) for controlling or performing various operations of the vacuum pumping system 1000, such as the operations of the various devices described herein. The computer programs or software may include system software and application software. System software may include an operating system (e.g., a Microsoft Windows® operating system) for controlling and managing various functions of the controller 1100, including interaction between hardware and application software. In particular, the operating system may provide a graphical user interface (GUI) displayable via a user output device 1110, and with which a user may interact with the use of a user input device 1108. Application software may include software configured to control or execute various operations of the vacuum pumping system 1000, and/or some or all of the steps of any of the methods disclosed herein.

The controller 1100 may also include a motor controller (or control module, or drive) 1112 configured to control the operation of the motor 504 (e.g., on/off states, power supplied, drive shaft speed, etc.) and thus the rotational velocity of the orbiting scroll 680 and inlet and outlet pressures of the pump head 502/602 (FIGS. 5, 6 and 10). The controller 1100 may also include one or more sensor interfaces 1114 configured to receive and process feedback (e.g., measurement) signals received from one or more sensors/meters/data loggers provided with the vacuum pumping system 1000, such as the inlet pressure sensor 614, outlet pressure sensor 616, run time meter 620, speed sensor 624, and temperature sensor 628 described above (FIG. 10). For example, the sensor interfaces 1114 may be embodied in different pieces of firmware or other electronic circuitry that are part of a microcontroller of the controller 1100. The sensor interfaces 1114 may communicate with motor controller 1112 and other components of the controller 1100 as needed to provide effective control of various operations of the vacuum pumping system 1000 the performing of any of the methods described herein. The firmware or other electronic circuitry embodying the motor controller 1112 also may be provided with the same microcontroller that includes the sensor interfaces 1114, or may be provided with separate hardware of the controller 1100. The controller 1100 may also include a data acquisition module (or DAQ) 1116 configured to further condition or process the signals received by the sensor interface(s) 1114 as needed for preparing data to be analyzed by the controller 1100. The controller 1100 may also include an inlet pressure data analyzer (or analyzing module) 1118 configured to analyze the acquired inlet pressure data and make the calculations, comparisons, and determinations in accordance with any of the methods described herein. For this purpose, the inlet pressure data analyzer 1118 may communicate with the sensor interfaces 1114 and/or DAQ 1116 to access or receive recently acquired inlet pressure data, and with the memory 1104 (e.g., a database thereof) to access or receive historical inlet pressure data, in accordance with the methods described herein.

FIG. 12 is a flow diagram 1200 illustrating an example of a method for assessing scroll pump tip seal wear (or determining a requirement for tip seal maintenance) in a scroll pump (e.g., scroll pump 500, FIGS. 5-10) according to an implementation of the present disclosure. The method may utilize various hardware components, modules and structures described herein. The method starts with providing a scroll pump 500 such as described herein (step 1202). Accordingly, the scroll pump 500 may include a pump inlet, a pump outlet, and a pumping stage. The pumping stage may include at least one first scroll and at least one second scroll nested together. The first scroll and/or the second scroll is/are configured to orbit about a drive axis relative to the other scroll to create one or more moving pockets between the first scroll and the second scroll effective to pump fluid from the pump inlet to the pump outlet. The first scroll includes at least one first scroll tip seal, and the second scroll (or each second scroll, or second and third scroll, in the case of a multi-stage scroll pump) includes at least one second scroll tip seal.

The method also includes providing historical pump data that are or include historical values of pump inlet pressure that were acquired from operation of a scroll pump over a historical period of time (step 1204). The historical pump data may be provided in any appropriate manner. As one example, providing the historical pump data may entail the processor 1102 accessing or receiving the historical pump data from a locally or remotely situated memory 1104 (FIG. 11) in which the historical pump data are stored (such as in a database of the memory 1104). The historical period of time precedes the current operation of the scroll pump 500 under assessment. The historical pump data may be acquired from measurements of pump inlet pressure taken during one or more prior operational runs of the same scroll pump 500 currently being assessed. Alternatively, the historical pump data may be acquired from measurements of pump inlet pressure taken during one or more prior operational runs of one or more other (different) scroll pumps (that is, scroll pumps other or different than the scroll pump 500 currently under assessment) that have the same configuration (e.g., same commercially available pump model, and/or same pumping capacity, and/or same size of scrolls, etc.) as the scroll pump 500 currently under assessment, and have been operated under the same operating conditions or parameters that the scroll pump 500 currently under assessment is being operated. Examples of such operating conditions or parameters may include, but are not limited to, operational mode (e.g., no-gas load, continuous-gas load, or series of cyclical pump-downs as described above and illustrated in FIGS. 1-4), composition of the working fluid being pumped (e.g., air or other gas or gas-phase mixture, etc.), power supplied to the motor 504 (FIGS. 5 and 10), pump speed (e.g., RPM), range of pump inlet pressure maintained during operational runs, etc. In the present context, when considering another (different) scroll pump, the term “same” encompasses the term “substantially similar”. For example, the value of a given operating condition or parameter of the different scroll pump may fall in a range of +/−10% of the value of the corresponding operating condition or parameter of the scroll pump 500 currently under assessment.

In other words, the historical pump data may be provided by operating the scroll pump 500 under assessment and measuring the pump inlet pressure to acquire the historical values, and/or accessing a database that includes the historical values of pump inlet pressure over the historical time period. The historical values that are part of (stored in) the database may be historical values that were acquired by operating the scroll pump 500 under assessment and/or operating one or more scroll pumps other than the scroll pump 500 under assessment.

The method further includes operating the scroll pump 500 currently under assessment to pump the fluid (e.g., to evacuate a vacuum chamber such as vacuum chamber 1004 shown in FIG. 10, or to provide compressed fluid to a downstream destination). The time span over which the scroll pump 500 is operated is or includes a recent time period that is subsequent to the above-described historical time period (step 1206). The historical time period may be any time period that precedes the recent time period, depending on the specific implementation of the method being performed (such as described by example below). Also depending on the specific implementation of the method being performed, the recent time period and the historical time period may change or shift over time (e.g., in terms of duration of the time period, starting point and/or ending point of the time period, etc.) with continued operation of the scroll pump 500 under assessment. For example, at a given point in time, a particular time-slice (or time interval, time sample, etc.) may be part of the recent time period. However, with continued operation of the scroll pump 500, that particular time-slice may no longer be the most recent time-slice of the recent time period or even one of the most recent time-slices of the recent time period. In such case, again depending on the specific implementation of the method being performed, that particular time-slice may no longer be (or considered to be) part of the recent time period but instead now part of the historical time period. In other words, the starting and ending points of the recent time period and the historical time period may get updated as the scroll pump 500 continues to be operated in additional runs.

The method further includes, during such current operation of the scroll pump 500, determining (e.g., by measurement or calculation) pump inlet pressure to acquire recent pump data comprising recent values of pump inlet pressure over the recent time period (step 1208). For example, continuously or intermittently during the recent time period, the above-described pump inlet pressure sensor 1012 (FIG. 10) may measure the pump inlet pressure and transmit representative measurement signals to the above-described controller 1100 (FIGS. 10 and 11). Alternatively, values of pump inlet pressure may be calculated or derived from readings from the current sensor 1014 and/or voltage sensor 1018 (FIG. 10). The controller 1100 may then store the acquired recent values in memory 1104 (FIG. 11) such as in a database of the memory 1104.

The method then includes comparing the determined recent pump data to the (stored) historical pump data (step 1210). The method then includes, based on this comparison, determining whether tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (step 1221). The analytical steps (processes, operations, algorithms, routines, etc.), particularly the comparing step 1210 and the determining step 1212, may be performed by the inlet pressure data analyzer 1118 in cooperation with other components of the controller 1100 and the scroll pump 100 described above and illustrated in FIGS. 10 and 11. Examples of the analytical steps are described further below in conjunction with FIGS. 13-20.

In some implementations, the determining step 1212 includes determining that the pump inlet pressure of the scroll pump 500 has increased over a long-term time period that is greater than a set (e.g., preset, predetermined, (pre-)specified, (pre-)selected, etc.) short-term time period. In other words, the determination is made in a way that distinguishes between, on the one hand, short-term fluctuations in pump inlet pressure that may be considered to be of no significance in relation to a requirement for tip seal maintenance versus, on the other hand, long-term, overall steady or continuous increases in pump inlet pressure that may be considered to be an indication that tip seal wear-out is imminent (or at least that further diagnosis is required or recommended).

In some implementations, if the determination is positive-that is, if the controller 1100 determines that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required-the method then includes producing a user-interpretable output indicating that tip seal maintenance and/or further diagnosis of the scroll pump 500 is required (step 1214). In response, the user may shut down the scroll pump 500 to perform maintenance, which may include replacing the orbiting scroll tip seal 282 and/or the fixed scroll tip seal 282 (FIGS. 6 and 9) with a new orbiting scroll tip seal and/or a new fixed scroll tip seal in the manner described above. Alternatively or additionally, depending on the output provided by the controller 1100, the user may initiate further diagnostics in the manner described above.

In an implementation, the flow diagram 1200 may represent a scroll pump, or additionally a vacuum pumping system, configured to carry out the steps shown in the flow diagram 1200. For this purpose, various components of the scroll pump 500 (FIGS. 5-9) and/or vacuum pumping system 1000 (FIG. 10) described and illustrated herein may be utilized.

Additional examples of a method for assessing scroll pump tip seal wear according to implementations of the present disclosure, particularly the comparing step 1210 and the determining step 1212 described above and illustrated in FIG. 12, will now be described with reference to FIGS. 13-20.

FIG. 13 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. Individual dots represent individual measurements of pump inlet pressure and thus individual pump inlet pressure values at corresponding points in time.

In the present example, the method defines a historical time period (h) of a selected duration. The values of pump inlet pressure acquired during the historical time period (h) are referred to as historical values. The historical values may have been acquired from previous operational runs of the scroll pump 500 currently under assessment, and/or from stored historical values acquired from previous operational runs of other scroll pumps, as described above. The method defines a recent time period of a selected duration that occurred after (succeeded) the historical time period (h). The values of pump inlet pressure acquired (by operating the scroll pump 500 under assessment) during the recent time period are referred to as recent values. The recent values may be acquired over the entire recent time period that starts immediately after the end of the defined historical time period (h), or over a recent time-slice that is a portion of the entire recent time period, for example, the most recent time-slice corresponding to the most recent operational run of the scroll pump 500. Line (d) in FIG. 13 corresponds to the most recent time-slice.

In the present example, the method calculates an average recent inlet pressure value from the recent pump data. Line (c) in FIG. 13 corresponds to the calculated average recent inlet pressure value. The method also calculates (or otherwise provides, e.g., by accessing a database) an average historical inlet pressure value from the historical pump data. Line (a) in FIG. 13 corresponds to the average historical inlet pressure value. The method then determines whether the average recent inlet pressure value (c) exceeds the average historical inlet pressure value (a) by more than a set threshold (or setpoint) value (b). The threshold value (b) is a pressure value that has been predetermined (e.g., empirically or experimentally) for the scroll pump 500 under assessment. A positive determination that the average recent inlet pressure value (c) exceeds the average historical inlet pressure value (a) by more than the threshold value (b) corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

FIG. 14 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates an average recent inlet pressure value (c) from the recent values of the most recent time-slice (a) (i.e., corresponding to the most recent operational run of the scroll pump 500 during which pump inlet pressure was measured and recorded). The method also calculates (or otherwise provides, e.g., by accessing a database) an average historical inlet pressure value (d) from the historical values of a historical time-slice (b) that precedes the most recent time-slice (a). The method then determines whether the average recent inlet pressure value (c) exceeds the average historical inlet pressure value (d) by more than a predetermined threshold (or setpoint) value (e). A positive determination that the average recent inlet pressure value (c) exceeds the average historical inlet pressure value (d) by more than the threshold value (e) corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

In the illustrated example, the threshold value (e) corresponds to the arithmetic difference between the average recent inlet pressure value (c) and the average historical inlet pressure value (d). In another example, the threshold value (e) may correspond to the ratio of the average recent inlet pressure value (c) and the average historical inlet pressure value (d). Other types of comparisons between the average recent inlet pressure value (c) and the average historical inlet pressure value (d) may be suitable for determining whether a defined threshold value has been exceeded.

In the illustrated example, the selected durations of the most recent time-slice (a) and the historical time-slice (b) are equal. Alternatively, the durations selected for the most recent time-slice (a) and the historical time-slice (b) may be different.

In the illustrated example, the historical time-slice (b) immediately precedes the most recent time-slice (a). More generally, however, the historical time-slice (b) may be any selected time-slice that precedes the most recent time-slice (a). For example, the historical time-slice (b) may be a time-slice that is three or four time-slices prior to the most recent time-slice (a). In either case, both the average recent inlet pressure value (c) and the average historical inlet pressure value (d) are running averages. That is, with continued operation of the scroll pump 500 and measurements of pump inlet pressure, a newer recent time-slice may be defined and utilized as the most recent time-slice (a). Moreover, a previously designated most recent time-slice, which is now a previous time-slice relative to the newly defined most recent time-slice (a), may now be defined and utilized as the historical time-slice (b) for purposes of a new or current assessment.

FIG. 15 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates a slope value (m) of inlet pressure over time for a selected recent time-slice of the recent time period, which may be the most recent time-slice as illustrated in FIG. 15. In FIG. 15, the slope value (m) is a linear slope calculated from the pressure increase (y) that occurred over a time-slice of a set duration (x). The method then determines whether the calculated slope (m) exceeds a set threshold value for slope. A positive determination that the slope (m) exceeds the threshold value corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

FIG. 16 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates a first slope value (m₁) of inlet pressure over time and a second slope value (m₂) of inlet pressure over time. The first slope value (m₁) is a linear slope calculated from the pressure increase (y₁) that occurred over the most recent time-slice of the recent time period having a set duration (x₁). The second slope value (m₂) is a linear slope calculated from the pressure increase (y₂) that occurred over a historical time-slice of the historical time period having a set duration (x₂). The method then determines whether the first slope value (m₁) exceeds the second slope value (m₂) by more than a threshold value. A positive determination that the first slope value (m₁) exceeds the second slope value (m₂) by more than the threshold value corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

In the present example, the threshold value may correspond to the arithmetic difference between the first slope value (m₁) and the second slope value (m₂). Alternatively, the threshold value may correspond to the ratio of the first slope value (m₁) and the second slope value (m₂). Other types of comparisons between the first slope value (m₁) and the second slope value (m₂) may be suitable for determining whether a defined threshold value has been exceeded.

In the illustrated example, the selected duration (x₁) of the most recent time-slice and the selected duration (x₂) of the historical time-slice are equal. Alternatively, the durations (x₁) and (x₂) selected for the most recent time-slice and the historical time-slice may be different.

In the illustrated example, the historical time-slice immediately precedes the most recent time-slice. More generally, however, the historical time-slice may be any selected time-slice that precedes the most recent time-slice. For example, the historical time-slice may be a time-slice that is three or four time-slices prior to the most recent time-slice. In either case, both the first slope value (m₁) and the second slope value (m₂) are running values. That is, with continued operation of the scroll pump 500 and measurements of pump inlet pressure, a newer recent time-slice may be defined and utilized as the most recent time-slice from which the first slope value (m₁) is calculated. Moreover, a previously designated most recent time-slice, which is now a previous time-slice relative to the newly defined most recent time-slice, may now be defined and utilized as the historical time-slice from which the second slope value (m₂) is calculated for purposes of a new or current assessment.

FIG. 17 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates a recent time-to-pressure value (b) corresponding to one or more pump-down cycles in the recent time period, which may or may not be the most recent pump-down cycle(s). In the present context, time-to-pressure refers to the length of time it takes for the scroll pump 500 to reduce the pump inlet pressure from an initial pressure down to a target operating pressure (or vacuum level), which length of time eventually increases with increasing tip seal wear as described above in conjunction with FIG. 4. The method also calculates (or otherwise provides, e.g., by accessing a database) an average historical time-to-pressure value (a) from time-to-pressure values corresponding to one or more pump-down cycles in the historical time period (h). The method then determines whether the recent time-to-pressure value (b) exceeds the average historical time-to-pressure value (a) by more than a predetermined threshold value. A positive determination that the recent time-to-pressure value (b) exceeds the average historical time-to-pressure value (a) by more than the threshold value corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

The threshold value may correspond to the arithmetic difference between the recent time-to-pressure value (b) and the average historical time-to-pressure value (a). Alternatively, the threshold value may correspond to the ratio of the recent time-to-pressure value (b) and the average historical time-to-pressure value (a). Other types of comparisons between the recent time-to-pressure value (b) and the average historical time-to-pressure value (a) may be suitable for determining whether a defined threshold value has been exceeded.

FIG. 18 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates an average recent pressure-at-set-elapsed-time value (b) from pressure-at-set-elapsed-time values corresponding to a set number of pump-down cycles in a recent time-slice (c) of the recent time period, which may or may not be the most recent time-slice. In the present context, the “set elapsed time” refers to the duration of each pump-down cycle, which in this example is set to be a constant duration for each pump-down cycle. The “pressure-at-set-elapsed-time” refers to the pump-down pressure, or vacuum level attained at the end of each pump-down cycle, which pressure eventually increases with increasing tip seal wear as described above in conjunction with FIG. 3. The method also calculates (or otherwise provides, e.g., by accessing a database) an average historical pressure-at-set-elapsed-time value (a) from pressure-at-set-elapsed-time values corresponding to a set number of pump-down cycles in the historical time period (h). The method then determines whether the average recent pressure-at-set-elapsed-time value (b) exceeds the average historical pressure-at-set-elapsed-time value (a) by a predetermined threshold value.

The threshold value may correspond to the arithmetic difference between the average recent pressure-at-set-elapsed-time value (b) and the average historical pressure-at-set-elapsed-time value (a). Alternatively, the threshold value may correspond to the ratio of the average recent pressure-at-set-elapsed-time value (b) and the average historical pressure-at-set-elapsed-time value (a). Other types of comparisons between the average recent pressure-at-set-elapsed-time value (b) and the average historical pressure-at-set-elapsed-time value (a) may be suitable for determining whether a defined threshold value has been exceeded.

FIG. 19 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates an average recent time-to-pressure value (a) from time-to-pressure values corresponding to pump-down cycles occurring in a recent time-slice (b) of the recent time period. The method also calculates (or otherwise provides, e.g., by accessing a database) an average historical time-to-pressure value (c) from time-to-pressure values corresponding to pump-down cycles occurring in a historical time-slice (d) of the historical time period. The method then determines whether the average recent time-to-pressure value (a) exceeds the average historical time-to-pressure value (c) by more than a predetermined threshold value. A positive determination that the average recent time-to-pressure value (a) exceeds the average historical time-to-pressure value (c) by the threshold value corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

The threshold value may correspond to the arithmetic difference between the average recent time-to-pressure value (a) and the average historical time-to-pressure value (c). Alternatively, the threshold value may correspond to the ratio of the average recent time-to-pressure value (a) and the average historical time-to-pressure value (c). Other types of comparisons between the average recent time-to-pressure value (a) and the average historical time-to-pressure value (c) may be suitable for determining whether a defined threshold value has been exceeded.

FIG. 20 is a graph plotting pump inlet pressure versus time illustrating another example of the method for assessing scroll pump tip seal wear. In this example, the method calculates an average recent pressure-at-set-elapsed-time value (a) from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a recent time-slice (b) of the recent time period. The method also calculates (or otherwise provides, e.g., by accessing a database) an average historical pressure-at-set-elapsed-time value (c) from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a historical time-slice (d) of the historical time period. In other words, the number of pump-down cycles set for the historical time-slice (d) is equal to the number of pump-down cycles set for the recent time-slice (b). The method then determines whether the average recent pressure-at-set-elapsed-time value (a) exceeds the average historical pressure-at-set-elapsed-time value (c) by more than a predetermined threshold value. A positive determination that the average recent pressure-at-set-elapsed-time value (a) exceeds the average historical pressure-at-set-elapsed-time value (c) by the threshold value corresponds to, or at least is part of, a positive determination that that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required (e.g., in accordance with the above-described step 1212 in FIG. 12).

The threshold value may correspond to the arithmetic difference between the average recent pressure-at-set-elapsed-time value (a) and the average historical pressure-at-set-elapsed-time value (c). Alternatively, the threshold value may correspond to the ratio of the average recent pressure-at-set-elapsed-time value (a) and the average historical pressure-at-set-elapsed-time value (c). Other types of comparisons between the average recent pressure-at-set-elapsed-time value (a) and the average historical pressure-at-set-elapsed-time value (c) may be suitable for determining whether a defined threshold value has been exceeded.

In another implementation, the method for assessing scroll pump tip seal wear involves performing several (two or more) of the different method examples described above and illustrated in FIGS. 13-20. For each method example performed, the method determines whether the set threshold value corresponding to that particular method example has been exceeded. In one example, if any one of these threshold values has been exceeded, then the method positively determines that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required. In another example, if at least two (two or more) of these threshold values have been exceeded, then the method positively determines that tip seal maintenance for the scroll pump 500 and/or further diagnosis of the scroll pump 500 is required.

Regarding any of the above-described implementations that compare data from a recent time-slice to a historical (previous) time-slice (e.g., as shown in FIGS. 14, 16, 19 and 20), the method is not limited to considering only a single recent time-slice or single historical time-slice. Instead, as a further implementation, multiple recent time-slices and multiple historical time-slices may be considered. In this case, the values of the characteristic of interest (e.g., average inlet pressure, P vs. t slope, time-to-pressure, pressure-at-set-elapsed-time, etc.) taken from the multiple recent time-slices may be aggregated, and the values of the characteristic of interest taken from the multiple historical time-slices may be aggregated. The recent aggregated values may then be compared to the historical aggregated values in accordance with the various method implementations described above.

It will be understood that one or more of the processes, sub-processes, and process steps described herein may be performed by hardware, firmware, software, or a combination of two or more of the foregoing, on one or more electronic or digitally-controlled devices. The software may reside in a software memory (not shown) in a suitable electronic processing component or system such as, for example, the system controller 1100 schematically depicted in FIG. 10 or 11. The software memory may include an ordered listing of executable instructions for implementing logical functions (that is, “logic” that may be implemented in digital form such as digital circuitry or source code, or in analog form such as an analog source such as an analog electrical, sound, or video signal). The instructions may be executed within a processing module, which includes, for example, one or more microprocessors, general purpose processors, combinations of processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate array (FPGAs), etc. Further, the schematic diagrams describe a logical division of functions having physical (hardware and/or software) implementations that are not limited by architecture or the physical layout of the functions. The examples of systems described herein may be implemented in a variety of configurations and operate as hardware/software components in a single hardware/software unit, or in separate hardware/software units.

The executable instructions may be implemented as a computer program product having instructions stored therein which, when executed by a processing module of an electronic system (e.g., the system controller 1100 schematically depicted in FIG. 10 or 11), direct the electronic system to carry out the instructions. The computer program product may be selectively embodied in any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as an electronic computer-based system, processor-containing system, or other system that may selectively fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this disclosure, a computer-readable storage medium is any non-transitory means that may store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer-readable storage medium may selectively be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device. A non-exhaustive list of more specific examples of non-transitory computer readable media include: an electrical connection having one or more wires (electronic); a portable computer diskette (magnetic); a random access memory (electronic); a read-only memory (electronic); an erasable programmable read only memory such as, for example, flash memory (electronic); a compact disc memory such as, for example, CD-ROM, CD-R, CD-RW (optical); and digital versatile disc memory, i.e., DVD (optical). Note that the non-transitory computer-readable storage medium may even be paper or another suitable medium upon which the program is printed, as the program may be electronically captured via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner if necessary, and then stored in a computer memory or machine memory.

It will also be understood that the term “in signal communication” or “in electrical communication” as used herein means that two or more systems, devices, components, modules, or sub-modules are capable of communicating with each other via signals that travel over some type of signal path. The signals may be communication, power, data, or energy signals, which may communicate information, power, or energy from a first system, device, component, module, or sub-module to a second system, device, component, module, or sub-module along a signal path between the first and second system, device, component, module, or sub-module. The signal paths may include physical, electrical, magnetic, electromagnetic, electrochemical, optical, wired, or wireless connections. The signal paths may also include additional systems, devices, components, modules, or sub-modules between the first and second system, device, component, module, or sub-module.

More generally, terms such as “communicate” and “in . . . communication with” (for example, a first component “communicates with” or “is in communication with” a second component) are used herein to indicate a structural, functional, mechanical, electrical, signal, optical, magnetic, electromagnetic, ionic or fluidic relationship between two or more components or elements. As such, the fact that one component is said to communicate with a second component is not intended to exclude the possibility that additional components may be present between, and/or operatively associated or engaged with, the first and second components.

It will be understood that various aspects or details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation-the invention being defined by the claims.

Claims

1. A method for assessing scroll pump tip seal wear, the method comprising:

providing a dry scroll pump comprising: a pump inlet; a pump outlet; a pumping stage comprising a first scroll and a second scroll nested together, wherein the first scroll is configured to orbit about a drive axis relative to the second scroll to pump fluid from the pump inlet to the pump outlet, and the second scroll is fixedly positioned in an axial direction relative to the drive axis; a first scroll tip seal mounted to the first scroll; and a second scroll tip seal mounted to the second scroll;

providing historical pump data comprising historical values of pump inlet pressure over a historical time period;

operating the scroll pump to pump the fluid, wherein the operating is done during a recent time period preceded by the historical time period;

during the operating, determining pump inlet pressure to acquire recent pump data comprising recent values of pump inlet pressure over the recent time period;

comparing the recent pump data and the historical pump data; and

based on the comparing, determining that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required.

2. The method of claim 1, wherein the scroll pump is a scroll pump under assessment, and the providing of the historical pump data comprises at least one of:

operating the scroll pump under assessment and measuring the pump inlet pressure to acquire the historical values;

accessing a database comprising the historical values of pump inlet pressure over the historical time period, wherein the historical values were acquired by operating one or more scroll pumps other than the scroll pump under assessment.

3. The method of claim 1, comprising, after the determining that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required, at least one of:

shutting down the scroll pump and replacing the first scroll tip seal and/or the second scroll tip seal with a new first scroll tip seal and/or a new second scroll tip seal;

producing a user-interpretable output indicating that the tip seal maintenance and/or the further diagnosis is required.

4. The method of claim 1, comprising, after the determining that further diagnosis of the scroll pump is required, outputting a communication to a user that directs the user to perform diagnostics on the scroll pump to determine whether tip seal replacement or other maintenance on the scroll pump is required.

5. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating an average recent inlet pressure value from the recent pump data;

calculating or providing an average historical inlet pressure value from the historical pump data; and

determining that the average recent inlet pressure value exceeds the average historical inlet pressure value by more than a threshold value.

6. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating an average recent inlet pressure value from the recent values of a most recent time-slice of the recent time period;

calculating or providing an average historical inlet pressure value from the historical values of a historical time-slice that precedes the most recent time-slice; and

determining that the average recent inlet pressure value exceeds the average historical inlet pressure value by more than a threshold value.

7. The method of claim 6, comprising at least one of:

wherein the threshold value is a difference between the average recent inlet pressure value and the average historical inlet pressure value;

wherein the threshold value is a ratio of the average recent inlet pressure value and the average historical inlet pressure value;

wherein the historical time-slice and the most recent time-slice have the same duration;

wherein the historical time-slice immediately precedes the most recent time-slice.

8. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating a slope value of inlet pressure over time, wherein the slope value is based on values of pump inlet pressure acquired during a set duration of the recent time period; and

determining that the slope value exceeds a threshold value.

9. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating a first slope value of inlet pressure over time, wherein the first slope value is based on values of pump inlet pressure acquired during a most recent time-slice of the recent time period;

calculating a second slope value of inlet pressure over time, wherein the second slope value is based on values of pump inlet pressure acquired during a historical time-slice of the historical time period; and

determining that the first slope value exceeds the second slope value by a threshold value.

10. The method of claim 9, comprising at least one of:

wherein the threshold value is a difference between the first slope value and the second slope value;

wherein the threshold value is a ratio of the first slope value and the second slope value;

wherein the historical time-slice and the most recent time-slice have the same duration;

wherein the historical time-slice immediately precedes the most recent time-slice.

11. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating a recent time-to-pressure value corresponding to one or more pump-down cycles in the recent time period;

calculating or providing an average historical time-to-pressure value from time-to-pressure values corresponding to one or more pump-down cycles in the historical time period; and

determining that the recent time-to-pressure value exceeds the average historical time-to-pressure value by a threshold value.

12. The method of claim 11, wherein the threshold value is at least one of:

a difference between the recent time-to-pressure value and the average historical time-to-pressure value;

a ratio of the recent time-to-pressure value and the average historical time-to-pressure value.

13. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating an average recent pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in the recent time period;

calculating or providing an average historical pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in the historical time period; and

determining that the average recent pressure-at-set-elapsed-time value exceeds the average historical pressure-at-set-elapsed-time value by a threshold value.

14. The method of claim 13, wherein the threshold value is at least one of:

a difference between the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value;

a ratio of the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value.

15. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating an average recent time-to-pressure value from time-to-pressure values corresponding to pump-down cycles occurring in a recent time-slice of the recent time period;

calculating or providing an average historical time-to-pressure value from time-to-pressure values corresponding to pump-down cycles occurring in a historical time-slice of the historical time period; and

determining that the average recent time-to-pressure value exceeds the average historical time-to-pressure value by a threshold value.

16. The method of claim 15, wherein the threshold value is at least one of:

a difference between the average recent time-to-pressure value and the average historical time-to-pressure value;

a ratio of the average recent time-to-pressure value and the average historical time-to-pressure value.

17. The method of claim 1, wherein the determining that the tip seal maintenance and/or the further diagnosis is required comprises:

calculating an average recent pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a recent time-slice of the recent time period;

calculating or providing an average historical pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a historical time-slice of the historical time period; and

determining that the average recent pressure-at-set-elapsed-time value exceeds the average historical pressure-at-set-elapsed-time value by a threshold value.

18. The method of claim 17, wherein the threshold value is at least one of:

a difference between the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value;

a ratio of the average recent pressure-at-set-elapsed-time value and the average historical pressure-at-set-elapsed-time value.

19. The method of claim 1, comprising:

calculating a plurality of calculated values comprising two or more of the following values: an average recent inlet pressure value from the recent pump data; an average recent inlet pressure value from the recent values of a most recent time-slice of the recent time period; a slope value of inlet pressure over time, wherein the slope value is based on values of pump inlet pressure acquired during a set duration of the recent time period; a first slope value of inlet pressure over time, wherein the first slope value is based on values of pump inlet pressure acquired during a most recent time-slice of the recent time period; a recent time-to-pressure value corresponding to one or more pump-down cycles in the recent time period; an average recent pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in the recent time period; an average recent time-to-pressure value from time-to-pressure values corresponding to pump-down cycles occurring in a recent time-slice of the recent time period; an average recent pressure-at-set-elapsed-time value from pressure-at-set-elapsed-time values corresponding to pump-down cycles occurring in a recent time-slice of the recent time period,

wherein the determining that the tip seal maintenance and/or the further diagnosis is required is based on determining that a threshold value corresponding to at least one of the plurality of calculated values has been exceeded, or determining that threshold values respectively corresponding to at least two of the plurality of calculated values have been exceeded.

20. A dry scroll pump, comprising:

a pump inlet;

a pump outlet;

a dry pumping stage comprising a first scroll and a second scroll nested together, wherein the first scroll is configured to orbit about a drive axis relative to the second scroll to pump fluid from the pump inlet to the pump outlet, and the second scroll is fixedly positioned in an axial direction relative to the drive axis;

a first scroll tip seal mounted to the first scroll;

a second scroll tip seal mounted to the second scroll;

a sensor configured to measure pump inlet pressure or to measure an operating parameter from which the pump inlet pressure can be calculated; and

a controller configured to assess tip seal wear, by controlling or performing an operation comprising: providing historical pump data comprising historical values of pump inlet pressure over a historical time period; operating the scroll pump to pump the fluid, wherein the operating is done during a recent time period preceded by the historical time period; during the operating, determining pump inlet pressure to acquire recent pump data comprising recent values of pump inlet pressure over the recent time period; comparing the recent pump data and the historical pump data; and based on the comparing, determining that tip seal maintenance for the scroll pump and/or further diagnosis of the scroll pump is required.