Metering Pump

Abstract

A fluid metering pump is provided having reciprocating pumps including a first fluid displacer and a second reciprocating pump include a second fluid displacer. A transmission and stroke adjuster assembly for couples a prime mover to each of said first and said second fluid displacers and converting a rotary movement of the prime mover into a reciprocating stroke movement of said first and said second fluid displacers resulting in a continuous fluid flow free of fluid pulsing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/381,996, filed Sep. 12, 2010, the entire of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to positive displacement pumps, and more particularly, metering pump that provides a continuous fluid flow of an adjustable volume.

BACKGROUND OF THE INVENTION

Metering pumps are commonly used to pump fluids when fluid flow rate must be precise and adjustable. The term “metering pump” is based more on the use of the pump rather than the actual type of the pump used. There are several classes of pumps that are typically used to meter fluids, including piston, diaphragm and peristaltic pumps. Each of these classes of pumps include a pump head and a motor that is operatively connected to the pump head to drive the pump head to pump or meter a fluid to a desired delivery location at a precise and adjustable flow rate. Further, pump heads may be classified as a loss-motion type or a no loss motion type. A loss-motion pump has a discontinuous positive fluid displacement during a fluid displacer's discharge stroke, whereas a no loss motion pump has a continuous positive fluid displacement. For the purpose herein, the invention is generally concerned with piston or diaphragm no loss motion type pumps or the like.

Conventional piston or diaphragm metering pump are well known in the art, and accordingly, a complete description of such is not warranted here for an understanding of the embodiments of the invention. However, in the basic concept a piston or diaphragm or the like may be termed as a fluid displacer that is moved within a housing having a pump cavity into which the fluid displacer is disposed. The displacer is reciprocated within the pump housing to create and collapse the volumetric size of the cavity. There is set of check valves or other form of valves located on the suction and discharge sides of the pump housing. The valves are so designed to allow the creation and collapsing of the cavity or chamber to create liquid displacement. The valve operational timing is so designed to isolate the differential pressure across the pump housing during its normal operation. The displacer within the pump housing is mechanically or mechanically hydraulically connected to some of transmission. Typically an electric motor applies rotary motion to the transmission to operate the metering pump and cause displacement.

Conventionally, the transmission includes an eccentric member that converts rotary motion to reciprocating motion. The transmission will have a form of mechanics for speed ratio and torque adjustment. There are other various ancillary components of common art within the pump to make a fully operational metering pump. They will have some form of mechanics or hydraulics to change the stroke length. Conventional no-loss pumps typically utilize eccentric members that create sinusoidal motion or similar to a sinusoidal motion for their reciprocating motion. These forms of reciprocating motion when applied to a duplex pump design cannot create sufficient substantially continuous non-pulsating displacement. The liquid being pumped always has period of zero velocity across the pump. This will cause undesirable pulsating liquid flow rates. They typically do not create the preferred continuous displacement motion of the invention.

Various electronic solutions have been proposed and utilized to reduce or eliminate the undesirable pulsating liquid flow rate. In one solution a synchronous motor is used to driver the displacers which are modulated through control electronics to control the fluid flow rate and reduce pulsing. Other solutions include digital controlled solenoid driven pumps which have been successful to a point in producing non-pulsating liquid flow rates. However, they have limited flow rates and pressures limitations due to the limitations of solenoid technology. They cannot create true continuous fluid flow at certain flow rates and fluid pressure.

There are a number of duplex mechanical metering pumps that incorporate continuous non-pulsating flow rate and incorporate mechanical stroke length modulation. A few use barrel cams, because they can create substantially uniform constant velocity stroke motion. When applied to two or more displacers they can create substantially uniform liquid flow rates. One example of a duplex pump utilizes a form of barrel cam style mechanical member. It can create continuous low pulsating flow rates. The stroke modulation is not integral. It is an added mechanical hydraulic mechanism. This adds extra components and complexity to its design and has not been readily accepted by the market. Another mechanical pumps may utilize a barrel cam, but do not have a stroke adjustor. As discussed above, there is exists digitally controlled synchronous motor driven metering pumps that have accomplished non-pulsating flow rates. They can create substantially non-pulsating flow rates, but current commercially offerings do not create substantially continuous flow rate delivery. They can achieve wide flow rate turn down creation as required for metering pumps They tend to be limited by cost and complexity. Embodiments, of a duplex version of the invention can deliver substantially or sufficient continuous flow rate delivery and low pulsations being imposed upon the pumped liquid. This preferred flow delivery is sustained through its zero to 100% stroke length modulation.

Various manufacturers produce pumps with single “simplex” or multiple pump heads “duplex”. Each pump head has a batch delivery of liquid displacement. Each batch is always defined by a two moments of zero liquid displacement with liquid displacement between those moments. These zero liquid displacement moments for each batch causes the liquid being displaced across the pump to go from a position of rest to high rates of velocity over very small increments of time back to a position of rest.

The all mechanical single and duplex pumps of common art typically create non-linear, non-proportional and non-continuous liquid flow rates during their normal operation. The more commonly sold pumps of common state of art require at least three or more displacers to create continuous liquid flow rates. Pumps that utilize three or more displacers can be phased to create a more substantially constant velocity across the pump at any given rotational speed. There is prior art for two displacers creating continuous flow rates. The invention can be designed for three or more displacers with integral stroke length modulation.

The physics of metering pumps is that they create batch flow rates. Each displacer displaces a given batch volume of liquid for each displacement cycle. The current state of art typically has the liquid being pumped going from zero velocity at the beginning of a batch to peak velocity and back to zero at the end of the batch. This causes negative pulsating liquid flow rates. This is transferred to the liquid up-stream and down-stream of the pump. This sudden change in liquid velocity creates mass acceleration problems applied to the liquid being pumped. It can create what is commonly called water hammer or cavitation. This is due to the sudden stopping of the liquid on the suction side of the pump at an end of a batch cycle. This causes a resultant high pressure to be enacted upon the pumped liquid on the suction side of the pump. This is due to the liquid on the suction side being a mass in motion that wants to stay in motion, but is suddenly stopped. At the end of a batch cycle the liquid pumped to the discharge side of the pump goes to zero velocity. The liquid has motion and tends to continue in motion. The sudden loss in liquid velocity causes a low pressure to be enacted upon the liquid at the discharge side of the pump. This process is repeated many times per minute. This occurs on the majority of applications of the current state of art for simplex and duplex metering pumps. A typical duplex pump has two batch liquid flows per revolution, but the pulsating flow remains. These negative flow characteristics are imparted to the liquid being pumped from the source to the point of application. Typically the source is a tank at a given distance to the pump. The application point is at given distance from the pump. These negative hydraulics characteristics created by the pump are transferred to the entire pumping system. The result is pulsating flow rates are transferred to the entire pumping system. This cause many negative issues. The invention shares these negative liquid hydraulics characteristics local at its suction and discharge at each of its reciprocating pump. Unlike the common art, the invention with two displacers can create substantially net constant liquid velocity across the pump. This is unlike the typical common art for a duplex pump with integral mechanical stroke adjustor. The overall pumping system is exposed minimal or virtually no pulsating liquid flow rates.

Typically the manufacturers of current state of art metering pumps recommend accessories to remedy the associated problems created by pulsating flow rates. If these accessories are not applied the pump may not operate properly and could cause a failure of the pump and pumping system. The typical solution to pulsating flow rates is the addition of peripheral equipment such as a back pressure valve and pulsation dampener or accumulator. They typically sufficiently mitigate the severity of the pulsating liquid flow rate. The addition of the pulsation dampener adds costs and complexity for a complete installation of a pumping system. It also adds its own set of maintenance issues. This same pulsating flow typically inherent in the current state of art of duplex metering pumps can cause liquid siphoning across the pump. This tends to negate the proper functioning of the check valves. It also can create the discharge piping to vibrate and be mechanically stressed. The recommend accessory to mitigate the problem is a back pressure valve. The valve is located on the discharge side of the pump. This creates enough pressure resistance to force the check valves to properly seat and to assure a satisfactorily operating pump. The back pressure valve reduces the potential for liquid siphoning across the pump. Some process applications have sufficient minimum back pressure to negate the requirement for a back pressure valve. It is typical for the pump manufacture to recommend the installation of the back pressure valve as a precaution of the potential problems. The back pressure valve adds costs and its own set of problems. The invention as a duplex pump creates sufficiently continuous low pulsating flow rates that it eliminates the need for pulsation dampeners or accumulators. In addition it further reduces the applications that would require a back pressure valve if certain minimum back pressure value is present.

There are process applications that utilize a flow meter in close proximity to these pumps that approximately verify that the pump is delivering the desired volumetric liquid required. They are at times used, but are more limited due to the typical pulsating flow for the duplex pumps of the current common art. Pulsating liquid is more difficult for a flow meter to accurately measure. Flow meters are typically calibrated with constant liquid head conditions at different constant liquid velocities. The typical state of art for duplex metering pumps with integral mechanical stroke adjustor do not create constant liquid velocities or constant head conditions. That is due to their pulsating flow rates that create variable liquid velocities. The variable liquid flow rate velocities cannot create constant head conditions on the suction and discharge sides of the pump. This virtually assures that the flow meter cannot measure the pumped liquid output to the stated accuracy and repeatability of the flow meter. This assures an accuracy offset that cannot be fully resolved. It would be desirable to pair a flow meter for verification, certification and calibration to national and international standards of a duplex metering pump. That is to match the flow rate creation of the metering pump to the flow meter. These international bodies such as the National Institute of Standards and Technology “NIST” a US based third party and outside the US such as DKD, NABL and others. Most manufacturers of higher accuracy flow meters calibrate to one or more of these recognized third party standards. All of these international flow calibration institutes, which certify to traceable internationally accepted standards, require constant liquid velocities. This constant liquid velocity is consistent with constant positive pressure of the inlet flow that is constant head of the source liquid. These third parties have developed measurement standards that allow manufacturers to assign quality controlled traceability of their calibration procedures. The manufacture can then state that their flow meters conform to a specific body of standards. Their flow meters will have a traceable accuracy and repeatability to a specific standard. The flow meter can claim a pedigree to a transferable standard. For example the flow meter would state that their flow meters are NIST traceable. The pulsating flow characteristics of the common art for duplex pumps tend to limit the use of flow meters, although they are used. The invention as a duplex pump can be calibrated to NIST or one of the other standards organizations requirements for transferability of pedigree. That is done by paring the suction or discharge side of the pump to a traceable flow meter. The invention as a duplex pump will be operated at fixed speeds and stroke length. The momentary produced flow creation of the invention will be compared to the momentary flow rate of the calibration flow meter. This comparison will create a calibration curve data sheet that will be certifying the traceability of the invention to a pedigree flow meter. The pedigree of the flow meter is transferred to the invention. No duplex metering pump of current art is claiming the ability to be calibrated to NIST, DKD, NSBL or any other like type standard. The invention with two displacers creates sufficiently continuous non-pulsating flow rates at substantially constant liquid velocities. These created substantially constant liquid velocities by the invention allow for a constant head creation in a close loop calibration rig. This means that the calibration requirement to these international bodies' standards for flow meter calibrations is transferrable to the invention. This compatibility of hydraulics allows the invention to be certified to any one of these standards and will be so claimed. This will give a more accurate and true verification of the pump's accumulated liquid flow rates over time as compared to the state of art. This also allows for more accurate momentary flow rate verification between the invention and a properly installed flow meter. There seems to be no traceable certified metering pump commercially available as of this filing.

A typical scenario for use of a metering pump is to add one liquid to another at a controlled desired continuous proportional ratio. Proper mixing allows for the optimum homogeneity and combines the two or more liquids. As common to the state of art for metering pumps they deliver pulsating liquid flow rates even with two displacers. This reduces the ability to achieve highly homogenous blends between two or more constituents or chemicals. The invention would allow for an optimum ratio of two or more liquids. This is due to the ability to have virtually one constant liquid velocity being combined to another virtually constant velocity liquid. The invention can maintain a fixed pumped flow rate delivery. The flow rate delivery by the pump is constant and if the primary chemical flow rate is constant then the invention can maintain a substantially constant fixed ratio. This is not achieved in the current state of art for duplex metering pumps. There are many industries that desire this ability.

Common to all metering pumps as with the invention is the need for some form of valves to be used to operate. The most common are ball check valves. Other types substitute the ball for cones or discs. Under certain conditions the check valves the balls, cones or discs can float off their seats when the pump is not operating. This allows for the source liquid to the suction side of the pump to flow across the pump. The source liquid is typically from a tank and under certain conditions the pump will drain the tank. This is commonly due to an operator error. The invention has an option for seating the diaphragms in their respective pump housing. This can be manually activated by an operator or automatically activated. This option is most effective when it is on the invention that has the smart electronics with the motor driven stroke adjustor. This automatic option would be programmed into the pump so that when the pump is shut-off or in stand-by it will seat its diaphragms before stopping. This assures that the pump will not allow the liquid to leak across the pump.

There does not seem to be common art for the ability of duplex or more displacer metering pump to mechanically engage and disengage a displacer in the field. This ability would allow for greater flow rate turn down, flexibility in manufacturing and field modification. The invention incorporates allow for an optional mechanical diaphragm engagement pin and mechanism for each driven diaphragm. This allows for a pump to be converted to a simplex pump to a duplex by adding a second pump housing in the field.

Any pump that does not produce continuous flows will have non-continuous torque demand to operate. This means that the torque demand will have peaks that require greater torque to operate at the peaks. For example a pump of common art that produces a sinusoidal volumetric displacement will have that peak torque of the sine curve. This means that a larger motor will be required to meet peak torque demands. The larger motor will require more current to operate. The non-continuous flow rate pumps will typically consume more power to operate than a continuous flow rate pump during its normal operation. The invention would typically have a smaller motor for any given volumetric displacement over the state of art of metering pumps

SUMMARY OF THE INVENTION

Embodiments of the present invention address and overcome the drawback of existing no-loss motion reciprocating metering pump by providing a metering pump including a transmission and stroke modulation assembly that provides a continuous and adjustable fluid flow without fluid pulsation.

Embodiments of the present invention also provide a metering pump including a transmission and stroke modulation assembly including three-dimensional, variable profile conjugate cams.

Embodiments of the present invention also provide a metering pump including a transmission and stroke modulation assembly that permits conversion between simplex and duplex pump configurations.

Embodiments of the present invention also provide a metering pump including a transmission and stroke modulation assembly that prevents fluid flow across the pump during non-operational periods

Embodiments of the present invention also provide a metering pump including a transmission and stroke modulation assembly that can be calibrated to a flow meter with constant head at a given constant velocity.

Embodiments of the present invention also provide a metering pump that can be calibrated to a flow meter with constant head at a given constant velocity

To achieve these and other advantages, in general, in one aspect, a fluid metering pump is provided. The fluid metering pump includes a first reciprocating pump have a first fluid displacer, a second reciprocating pump having a second fluid displacer and a transmission and stroke adjuster assembly for coupling a prime mover to each of the first and the second fluid displacers and converting a rotary movement of the prime mover into a reciprocating stroke movement of the first and the second fluid displacers. The transmission and stroke adjuster assembly includes a driven shaft rotatable about an axis of rotation, first and second three-dimensional cam members mounted to the driven shaft for conjoined rotation therewith, the first and second cam members are congruent with respect to one another, a first pair of followers in contact with the first cam member on opposite sides thereof, the first pair of followers connected to the first fluid displacer and imparting a reciprocating motion on the first fluid displacer during rotation of the driven shaft, a second pair of followers in contact with the second cam member on opposite sides thereof, the second pair of followers connected to the second fluid displacer and imparting a reciprocating motion on the second fluid displacer during rotation of the driven shaft, and, wherein the first cam member and the second cam member each have a non-cardioid shape cam profile that results in a constant velocity reciprocation motion of the first and second pair of followers during rotation of the driven shaft.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate by way of example and are included to provide further understanding of the invention for the purpose of illustrative discussion of the embodiments of the invention. No attempt is made to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Identical reference numerals do not necessarily indicate an identical structure. Rather, the same reference numeral may be used to indicate a similar feature of a feature with similar functionality. In the drawings:

FIG. 1 is a top view of pump in accordance with an embodiment of the invention;

FIG. 2 is a perspective view of a pump in accordance with an embodiment of the invention;

FIG. 3 is a side view of a pump in accordance with an embodiment of the invention;

FIG. 4 is a partial cross-sectional view of a pump in accordance with an embodiment of the invention;

FIGS. 5a and 5b are representative illustrations of positional locations of oppositely located and simultaneously driven diaphragm members;

FIGS. 6a and 6b are representative illustrations of positional locations of oppositely located and simultaneously driven diaphragm members;

FIGS. 7a and 7b are representative illustrations of an operational position of oppositely located and simultaneously driven diaphragm members;

FIG. 8 is a diagrammatic perspective view of a three dimensional conjugate cam in accordance with the principles of the present invention;

FIG. 9 is a diagrammatic end view of the conjugate cam of FIG. 8;

FIG. 10 is a diagrammatic, partial assembly of the conjugate cam and drive shaft;

FIG. 11 is a diagrammatic plan view of the conjugate cam of FIG. 8 including spherical followers;

FIG. 12 is a diagrammatic perspective, exploded view of a transmission and stroke adjuster assembly in accordance with an embodiment of the invention;

FIG. 13 is a diagrammatic side view of the transmission and stroke adjuster assembly partially assembled;

FIG. 14 is a diagrammatic perspective view of the transmission and stroke adjuster assembly with portions thereof removed for purpose of illustrative clarity;

FIG. 15 is a diagrammatic perspective view of the transmission and stroke adjuster assembly with portions thereof removed for purpose of illustrative clarity;

FIG. 16 is a diagrammatic top view of the transmission and stroke adjuster assembly;

FIG. 17 is a diagrammatic side view of the transmission and stroke adjuster assembly;

FIG. 18 is an illustrative plan view of an alternative embodiment in accordance with the invention; and

FIG. 19 is a fluid flow diagram illustrating fluid flow characteristic of embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 to 3, a metering pump representatively embodying the principles of this invention is designated generally by reference number 114. Metering pump 114, as illustrated here, takes the form of a duplex pump head having a pump head casing or gear box 109 supporting oppositely positioned reciprocating pumps 101a and 101b. Casing or gear box 109 further supports a prime mover mounting flange 105 for the attachment and the connection of a prime mover to the pump head 114, stroke length indicator 108 that operates to indicate the stroke length of each fluid displacer, a stroke length control knob 104 that is operated by a user to adjust the stroke length of each fluid displacer (herein illustrated as diaphragms), and pump head mounting flanges 111 for attaching the pump head to a suitable mounting surface.

Each reciprocating pump 101a and 101b include fluid suction ports 150a and 150b, respectively, and fluid discharge ports 152a and 152b, respectively. Fluid suction ports 150a and 150b are configured to be connected to a source of fluid by suitable fluid carrying conduits or the like. Fluid discharge ports 152a and 152b are configured to be connected suitable fluid carrying conduits for the delivery of the pumped fluid. As it will be further described below, reciprocating pumps 101a and 101b include access ports 110a and 110b, respectively, that permit an operator access to the driven shaft connected to each respective fluid displacer for either the engagement or disengagement of the fluid displacer from its driven shaft to enable or disable the operation of the respective fluid displacer. To this end, the representatively illustrated duplex pump head 114 may be converted between a simplex configuration and a duplex configuration.

In FIG. 4, there is illustrated a partial cross sectional view of a representative embodiment of the pump head 114 of the invention. As depicted here, housing 109 contains transmission and stroke adjustor assembly 90. Further depicted are diaphragms 106a and 106b, connected to shafts 12a and 12b, respectively, of the transmission and stroke adjustor assembly 90. As will be further discussed in detail below, a prime mover such as an electric motor, hydraulic motor or the like is operatively connected to the transmission and stroke adjust assembly 90 to rotatably drive shaft 58 of the transmission which, through the transmission, causes the reciprocation of shafts 12a and 12b, and thus also the reciprocation of diaphragms 106a and 106b that are connected thereto.

With initial reference to FIGS. 5a and 5b, there is representatively illustrated cross sectional views reciprocating pumps 101a and 101b, wherein pump 101a is illustrated in FIG. 5a and pump 101b is illustrated in FIG. 5b. Each pump 101a and 101b there is a liquid flow channel 138a, 138b that has a seating area 132a, 132b across which diaphragms 106a, 106b are disposed, an inwardly flow check valve 102a, 102b disposed across fluid suction inlet 150a, 150b, and an outwardly flow check valve 102c, 102d disposed across fluid discharge 152a, 152b. The reciprocation of diaphragms 106a, 106b with respect to seating area 132a, 132b results in a fluid pumping action from suction inlet 150a, 150b through flow channel 138a, 138b and out fluid discharge 152a, 152b. This pumping action has been long established in the field of the invention and is readily understood by one skilled in the art. Accordingly, a more detailed explanation of the physics and related structure permitting this pump action is not warranted here.

Further illustrated in FIGS. 5a and 5b, and subsequently in FIGS. 6a and 6b, are various positions of diaphragms 106a, 106b through a single stroke action. In FIG. 5a, diaphragm 106a is shown in a “Full Suction” position, and in FIG. 5b, diaphragm 106b is shown in an opposite “Full Stroke” position. In FIG. 6a, diaphragm 106a is shown in a “Full Stroke” position, and in FIG. 6b, diaphragm 106b is shown in the opposite “Full Suction” position. At the full suction position diaphragm 106a, 106b is at the momentary end position of P3. At the full stroke position diaphragm 106a, 106b is at the momentary end position of P2. At these two positional moments P2 and P3 diaphragms 106a, 106b will not have any motion. These two positions can be termed bottom dead center and top dead center respectively. These are the cross over positions where the diaphragms 106a, 106b change their direction of reciprocating motion. This change in reciprocating motion for each diaphragm is phased to happen at the same moment in time. When diaphragm connector shafts 12a and 12b respectively reciprocate their diaphragms 106a, 106b they will do so with substantially constant velocity of motion. Diaphragms 106a, 106b will move substantially uniform velocity between positions P2 and P3 and between P3 and P2. The transmission and stroke adjustment assembly 90 utilizes a conjugate three dimensional cam that can create various characterized reciprocating motions. To this end, diaphragms 106a, 106b have near substantial uniform motion. They will have constant motion between positions P2 and P3 and P3 and P2, but the velocity will moderately vary between these positions of no momentary displacement. For example there can be some rate in velocity change at both ends of the displacing cycle for each diaphragm as noted in FIG. 19. As the examples of volumetric displacement V3 and V4 depict. The displacement gap between V3 and V4 is so small that the liquid being pumped across the pump 114 never comes to zero velocity. That is the liquid approaching the pump and discharging the pump has sustained motion at all times. The pumped liquid will have sustained motion, but not absolute constant velocity. These forms of reciprocating motion as described with proper phasing of the diaphragms 106a, 106b is accomplished by the invention. This assures the invention shall keep the liquid pumped in sufficiently constant motion during its operation.

Turning to FIGS. 7a and 7b, diaphragms 106a, 106b are representatively illustrated in an operation state wherein both diaphragms are simultaneously positioned at P 1. In this position, diaphragms 106a, 106b are fully seated within each of their respective reciprocating pump 101a, 101b and prevent fluid from leaking or siphoning across the pump. This is a safety feature that can be manually done by the proper manual rotation of stroke adjustor knob 104. It can also be an automated feature if the invention is an automated version.

The transmission and stroke assembly 90 of pump 114 utilizes aspects of co-pending U.S. patent application Ser. No. 13/084,086, the entirety of which is incorporated herein by reference. In FIGS. 8 through 11, there is illustrated a conjugate cam 50 reflecting the principles of the aforementioned U.S. patent application. The eccentric three dimensional conjugate cam 50 includes two integrated elongated cams 52 and 54. The surface areas are integral thrust washer 48 of the cam assembly 50. The cam assembly 50 has an internal full axial hole 56 with spline grove lines 57 through its center. It is parallel to center line 36. The cams 52 and 54 each have a surface profile 53 with a length of each cam of “Y”.

Each cam 52 and 54 are congruent geometries that are properly integrated to create a conjugate cam assembly 50. The cam surface areas 53 of cams 52 and 54 have an area along the dimension “Y” that is expanded from a position of no displacement to maximum displacement to one direction along “Y”. To the opposite direction from a position of no displacement for both cams 52 and 54 begins a tapered outward area 107 about the center 36. These two tapered areas 107 expand their surface areas 53 and gradually expand to approach the surface areas 112 for each congruent cam 52 and 54. The cams 52 and 54 circular surface areas 112 are expanded surface areas about the center 36. This surface area of 112 for each cam 52 and 54 shall have a radius greater than the most eccentric position along the cam profile 53. These surface areas 112 expand the FIG. 12 cam follower 82 halves 82a and 82b to cause the diaphragms 106a, 106b to seat in their respective reciprocating pump 101a, 101b at internal surface area 132a and 132b, as illustrated in FIGS. 7a and 7b. The seating will be at position P1.

FIG. 10 is a three dimensional conjugate cam 50 that is fitted over and mates to its drive shaft 58. There is a high tolerance clearance between the axial hole 56 of the three dimensional cam assembly 50 to its mated splined cam drive shaft 58. The drive shaft 58 has raised splines 59 that integrate into the cam assemblies splined groves 57. This creates an integrated rotationally relationship and an aligned movable lateral motion relationship of the three dimensional cam assembly 50 to its mated cam drive shaft 58. The splined drive shaft 58 has a drive gear 62. It will mate with drive gear shaft 116 as shown in FIG. 12. There are example positional points for three of the four sphere bearings 84a or 84b. The bearings 84a and 84b are at positions with respect cams 52 and 54 where they are initially tangential to the inclined area 107. They are positional at tangents 44 to the two cams 52 and 54 and the incline area 107. The drive shaft 58, cam assembly 50 and drive gear 62 comprise the shaft driven three dimensional cam assemblies 50 as an assembly 92.

FIG. 11 is the cam assembly 50 with the four spherical bearings of two 84a and two 84b. These bearings have their centers intersecting to the two planes 100, one sphere bearing center 84a and 84b each plane 100 as shown. The plane 100 is defined as the intersecting point of the center of the sphere bearings 84a and 84b. The drawing depicts spherical bearings, but other designs can be used such as rollers. There are limitations to the load that spheres can bear. For higher force applications the sphere bearings can be substituted for roller followers. The rollers and their support mechanisms are not depicted. If the roller followers were deployed they would have to be allowed to freely pivot to stay parallel to the cam profiles 53. In addition, FIG. 11 depicts a tapered circular area 107 and a circular area of 112 for about center line 36 for each cam 52 and 54. This is an option to cause the diaphragms 106a, 106b to expand outward to seat to a mating position in their respective reciprocating pump 101a, 101b. This pump hydraulic sealed position is sustained whether the pump is running or shut-off. The cam assembly 50 is laterally moved back to allow bearings 84a and 84b form tangents with the each cam eccentric portion of 52 and 54 and the stroke creation will begin again.

FIG. 12 is an exploded view of the modular cam mechanism assembly 90. Only the pertinent components are shown, there are some ancillary components not depicted to provide a better view of the more critical components. The drive shaft 58 is supported by bearings 64. These bearings 64 are held in the cam assembly frame 68. The conjugate cam assembly 50 is positional held by the stroke adjustor frame 70. The stroke adjustor frame 70 has two perpendicular arms 72 that are in positional contact with thrust washers 48 of the cam mechanism 50. The stroke adjustor rod 76 is connected to stroke adjustor frame 70 at threaded holes 74 and locked in place by nut not shown. The threads of 74 and 76 are not detailed. The stroke adjustor rod 76 is aligned and held to the cam assembly frame 68 by alignment linear bearing area 80 the actual bearing is not detailed only the hole is shown. When the stroke adjustor frame 70 is held in place within the cam assembly frame 68 the rod 76 and cam assembly frame 68 is constrained and aligned to allow for lateral motion only.

The stroke adjustor frame 70, stroke adjustor rod 76 and arms 72 comprise the stroke adjustor assembly 94 that fits into the cam assembly frame 68. The cam stroke adjustor shaft 76 has a drive gear 121. That drive gear has internal threads 123 not detailed. Gear 121 interacts with a worm gear and shaft 119. The stroke adjustor knob 104 not shown is connected to the shaft 119. The cam assembly 50, drive gear 62 and the motor drive shaft 58 comprise the major components for the driven cam assembly 92. The drive shaft gear 62 meshes with the worm gear drive shaft 116. The worm gear drive shaft is connected to the drive motor (not shown) that is mounted to motor flange mount 105 not shown. There would be some form of coupling between 116 and the motor shaft not shown. The follower assembly 88 is comprised of 82a and 82b of 82, diaphragm drive shafts 12a and 12b, spherical bearings two 84a and two 84b, springs 127 and four bolts 96. In addition the sphere bearings 84a and 84b shown as detail “D” are constrained by contact to small ball bearings 126 that are held in place the flat bearing race 125. That is held in place by flanged diaphragm shafts 12a and 12b. This supports the sphere bearings 82a and 82b and allows them to rotate.

The follower holder assembly 82 has two pieces 82a and 82b. The holder assembly 82 confines the four bearings of two pairs of 84a and 84b. When the bolts 96 attach the two cam follower haves 82a and 82b the four bolts 96 pass through springs 127 through both 82a and 82b and 12a and 12b. There are four or eight springs 127 depending on design and are held in compression between each cam follower plates 12a or 12b and the head of bolt heads 96 and their nuts (not shown). Certain designs may incorporate external springs to accomplish the same effect of springs 127. This configuration maintains the sphere bearings 84a and 84b to stay in contact with the cam surface 50. The sphere bearings 84a and 84b are mechanical connected to each cam follower half 82a and 82b that is positively connected to flanged diaphragms shafts 12a and 12b. This is true when each cam follower 82a or 82b is expanding away from the center 36 and a diaphragm 106 is displacing. When a diaphragm 106 is in return and creating a cavity the spring 127 forces have to be sufficient to pull back the diaphragms 106 as if 12a or 12b were joined rigid. That is that the follower 82 was one solid piece. The springs 127 allow for manufacturing tolerances and to allow the diaphragms to be expanded outward during hydraulic shut-off. As depicted in the drawings the spherical ball 84a and 84b are incorporated in this design, but it can be of a different design, such as rollers. The spherical geometry is the simplest to design, but may have practical design limitations that a cylindrical roller would solve. The follower assembly holder 88 encapsulates the cam assembly 50.

The cam follower assembly 88 is continuously constrained by its tangents 44 to the surface area profiles 53 of the conjugate cams 52 and 54. The cam follower assembly 88 is further constrained by the connector shafts 12a and 12b being held in rigid alignment within the linear bearings 64. This combination of two defined mechanical constraints holds the cam follower 88 assembly in proper position. As shown on FIG. 20 assemblies 88, 92, 94 and cam assembly frame 68 with its bearings 64 comprise the cam assembly mechanism 90.

FIG. 13 is a drawing of the cam assembly 50 on its splined drive shaft 58. The drive shaft 58 is supported by bearings 64. The cam drive gear 62 hidden is connected to drive shaft 58. The sphere bearings 84a and 84b are shown without the cam follower assembly 82. The cam drive shaft with worm gear 116 that then goes up through the motor flange 105 that would then be connected to a drive motor not shown. The gears 62 and 116 interact to cause the motor rotation to be transferred to the drive shaft 58 that is then applied to the cam assembly 50. The stroke adjustor knob 104 is connected to the worm drive shaft 119 that engages gear 121. The 121 gear has internal threads 123 not shown, that engages with the threads on the stroke adjustor shaft 76. The stroke shaft 76 is supported by bearing area 80 as shown in FIG. 12. The gear 121 is positional constrained by two nuts washers 95 that are to either side of gear 121. This allows the rotation of gear 121 to cause the lateral motion of stroke adjustor frame 94. The rotation of gear 121 and its internal threads 123 to shaft 76 drives the shaft 76 lateral in both directions.

FIG. 14 is an inverted cut away view of the driven cam assembly with its shaft and stroke adjustor for overall assembly 90. The cut away view shows a diaphragm 106 and the motorized worm gear drive shaft 116. The drawing depicts the engagement of the drive shaft gear 62 and the geared stroke adjustor shaft 119.

FIG. 15 is an additional inverted cut away view of the complete cam mechanism and stroke adjustor assembly 90 without diaphragms 106. As compared to FIG. 14 it adds the stroke adjustor worm gear shaft 116 that is engaged with gear 121.

FIGS. 16 and 17 are additional views of the cam assembly with drive gears, stroke adjustor assembly as assembly 90. It has the drive gearing for the stroke adjustor mechanism and for driving the cam assembly. It shows the diaphragms 106 and the disengagement section 130 of diaphragm drive shafts 12a and 12b as per Detail “E”. This is where the shafts 12a and 12b are split and are joined. This section is where each shaft 12a and 12b interacts and can be coupled or uncoupled. The hole 131 accommodates a through bolt and nut not shown or it is threaded section for a bolt. The bolt or pin not shown would allow for the engaging and disengaging of diaphragms 106a, 106b on either side of the pump 114. All pumps of common art will have some form of mechanical connection between its diaphragm and diaphragm drive shaft. There are no known pumps that are designed to allow this as a field addition. The invention is so designed that it can built as a single headed diaphragm pump and allow for the addition of a pump head 101 and its diaphragm 106 to be added in the field. This is achieved with the rated volumetric liquid displacement specified and at its stated accuracy for the invention. This also allows for a single headed pump to ship as a left hand or right hand pump. The preferred side of pump head can be changed in the field. This also allows for a duplex pump to operate with only one diaphragm 106 in a pump housing 101 engaged. That is the other diaphragm 106 in the second pump housing 101 in place, but disengaged and not displacing.

FIG. 18 is a top view of the pump 134 with only one pump housing 101 as compared to the duplex pump 114. A pump housing 101 can be mounted to either side of the pump 134. Cap 128 is to cover the pump shaft 12a or 12b for safety and to keep the pump gear housing 109 sealed. The diaphragm pump shafts 12a and 12b will always be reciprocating on the both sides of the transmission housing 109. This is true even though the pump is built with one pump housing 101. The seal cap 128 can be removed and a pump housing 101 can be added to change the pump to a duplex pump 114. The additional pump housing 101 to be added will have the engagement section 130 connected. The engagement section 130 as shown in Detail “E” will have a through bolt or pin incorporated through hole 131 when a second diaphragm 106 is added. It should be noted that as a single headed pump it will create non-continuous pulsating flow rates.

FIG. 19 is an illustration of examples for two liquid volumetric displacements at two given stroke lengths (50% and 100%) and at a constant rotational speed for a duplex pump. Where V1 is the theoretical volumetric displacement for assigned diaphragm D1 and V2 is the theoretical volumetric displacement for assigned diaphragm D2. Whereas the flow rate for V1 and V2 have substantially constant velocity of displacement respectively created by D1 and D2. That is due to the substantially uniform or constant velocity of reciprocating motion for D1 and D2. The volumetric displacements of V1 and V2 by diaphragms D1 and D2 are theoretical and the actual volumetric liquid displaced may have a small difference. They could be closer to V3 and V4 or some other curve of displacement. The invention's conjugate cam can be designed to create other forms of volumetric displacement such as V3 and V4 may be optimal. The invention is so designed that the peak liquid displacement velocities are minimized. For example the displacement curves of V1 and V2 do not have the peak velocities that a sinusoidal displacement would create over the same time constant. The phasing of the diaphragms D1 and D2 is such that the volumetric displacement across the pump is continuous. The volumetric displacement across the pump needs to be substantially continuous, but will have some variations of displacement velocities. The volumetric displacements of V3 and V4 are examples of sufficient sustained displacement with less than perfect constant velocity. In additions the actual design mechanics and hydraulic issues can cause different displacement curves. It is a matter of acceptable amounts of very low pulsating flow rates by the invention. The non-continuous displacement of V1 by diaphragm D1 creates an undesirable intermittent pulsating flow rates as defined by V0. Whereas V0 is when the diaphragm is in a suction cycle and is not displacing liquid. The non-continuous displacement of V2 by diaphragm D2 creates an undesirable intermittent pulsating flow rates as defined by V0. Whereas V0 is when the diaphragm is in a suction cycle and is not displacing liquid. The gap between the displacing and non-displacing for each diaphragm is V0. The cycle rate of the displacement C is 360° of rotational operation. That is the 360° cycle rate C is repeated as C+C2+C3 continuous during the invention's rotational operation. As mentioned each displacement V1 and V2 are phased as to substantially assure that one is displacing while the other is in suction. This phasing is such that the volumetric displacement is typically split 180° to each diaphragm D1 and D2. The combined volumetric liquid displacements of V1+V2 have resultant properly phased alternating flow rates as V1+V2=Q3. The substantially continuous flow rate of Q3 creates substantially desirable continuous non-pulsating flow rates by the invention. A critical and unique feature of the invention is how stroke length is changed. If the pump was operating at the same speed as Q3, but at 50% of maximum stroke length then V5 and V6 would be 50% of V1 and V2. The continuous flow rate Q₄ would be 50% of Q₃. The pump creates substantially continuous uniform reciprocating displacement motion with resultant continuous non-pulsating flow rates. The stroke adjusting mechanism combined with the invention's conjugate three dimensional cam assembly substantially assures Q₃ is as described. That is continuous uniform flow rate generation that can be equally proportionally changed by its stroke length change For any given stroke length position the output flow rate would be substantially uniform to a given rotational speed.

Operationally when the Pump's motor not shown rotates the worm gear drive shaft 116 it turns the geared drive shaft 62 that in turn rotates its integral drive shaft 58 that in turn rotates the cam assembly 50. The shaft 58 and the cam assembly 50 are constrained to rotate together due to their splined relationship of 57 and 59. The follower assembly 88 is encapsulating the cam assembly 50 to assure constant tangents of the sphere bearings 84a and 84b to cam assembly 50. The cam assembly 50 is free to laterally move on shaft 58. The rotation of the cam assembly 50 will impart the reciprocating motion to the follower assembly 88. This reciprocating motion would be prescribed by the conjugate cam's 52 and 54 profiles 53. That is the resultant tangents of sphere bearings 84a and 84b at that cam profile 53 at planes 100 will impart a prescribed reciprocating motion to the follower 88. The theoretical planes 100 move lateral with the centers of bearings 84a and 84b. The form of reciprocating motion will be as described herein this writing. The motion will be transferred to the diaphragm shafts 12a and 12b. In turn transferred to the diaphragms 106. As the motor drives the invention each diaphragm 106 creates batch displacement. The properly phased summation of the two batch displacements will create very low or non-pulsating continuous liquid flow rates. The pump 114 liquid displacement will be as shown and described in FIG. 19. The pumps 114 and 134 have an integral stroke adjustor assembly 94 as shown in FIGS. 12 and 13. As shown in FIG. 13, when the stroke adjustor knob 104 (the stroke adjustor knob can be substitute for a motor not shown) is rotated it turns the stroke adjustor worm gear shaft 119 that turns gear 121 that has internal threads 123 that engage the stroke adjustor shaft 76 threaded section that causes the shaft 76 to move laterally moving the stroke adjustor frame 70. This moves the stroke adjustor assembly 94. The frame 70 has two arms 72 that are in contact with the cam assembly 50 at washer areas 48. The cam assembly 50 in turn is driven lateral to either direction when the stroke adjustor assembly 94 moves. This changes the positional relationship between the cams 52 and 54 surface areas 53 and the follower's sphere bearings 84a and 84b. That in turn changes the stroke length and the resultant displacement by each diaphragm 106a, 106b. This method of lateral motion of the cam assembly 50 can move the bearings 84a and 84b to cam surface area 107 a tapered incline area to a circular area 112. FIGS. 7a and 7b shows when the bearings 84a and 84b are riding on the surface area 112 the diaphragms 106a, 106b will be forced to expand outward and cause the face of each diaphragm 106a, 106b to seat within each pump housing 101a, 101b. When the follower bearings 84a and 84b are riding on the surface areas 107 or 112 the follower assembly haves 82a and 82b will expand apart. The springs 127 will allow the expansion, but keep the bearings 84a and 84b to stay in contact to areas 107 or 112. As per FIGS. 7a and 7b, when the diaphragms 106a, 106b are in position P1 the liquid cannot leak across the pump 114 or 134. This can be manually or automatically done depending on the pump configuration. This hydraulic shut-off position can be changed back to displacing by moving the cam assembly 50 to the opposite direction. The shut-off can be maintained even if the motor is running There are other minor ancillary components required to have a properly operating system not described. The volumetric displacement can also be change by changing the speed of the motor as is common to the state of art metering pumps. There is a section of the diaphragm shafts 12a and 12b that are split as shown in detail “E” on FIG. 16. This split section 130 of the diaphragm shafts 12a and 12b has a hole 131 that accommodates a pin or bolt that connects the shaft. This is a form of coupling can be automated as well, but not described within. This ability to couple the diaphragms 106a, 106b is incorporated to allow a single headed pump 134 (FIG. 18) to add a pump housing 101 in the field by a user of the pump to double the capacity of pump and create a duplex pump 114. The cap 128 is removed with the pump 134 powered off to allow a new pump housing 101 to be bolted on with bolts 113. The proper piping installations would be added and the pump turned back for doubling of the pump flow rate capacity. It also allows the user to change the side that the pump housing 101 is connected to the transmission housing 109. This feature can also be done in the field.

From the above description advantages of embodiments of the invention herein are readily recognized by those skilled in the field of the invention. Alternative embodiments are possible. In an alternative embodiment, conventional prime mover control electronics and prime mover control methods may be employed. In such an embodiment, the stroke control of the diaphragms may be automated by replacing the control knob 104 with an electric motor that is interfaced with the prime mover control electronics. To this end, the stroke length may be adjust remotely in a similar manner to conventional methods of remotely controlling the prime mover through the control electronics and an established communication link between the control electronics and a remotely located controller or computer interface. In another alternative embodiment, the diaphragms could be replaced with pistons or other reciprocating displacement mechanisms. In another alternative embodiment, three or reciprocating pump containing displacers (diaphragms, pistons, or the like) may be phased about the pump in order to overlap suction and discharge phases, e.g. to have 240° of suction and 120° of discharge for each diaphragm. It would be provide continuous non-pulsating flow rates. It can be built as a four diaphragm pump for additional capacity with the same features as the duplex embodiment. Other embodiments are also possible within the scope of the invention and the claims.

Claims

1. A fluid metering pump comprising:

a first reciprocating pump including a first fluid displacer;

a second reciprocating pump include a second fluid displacer

a transmission and stroke adjuster assembly for coupling a prime mover to each of said first and said second fluid displacers and converting a rotary movement of the primer mover into a reciprocating stroke movement of said first and said second fluid displacers;

said transmission and stroke adjuster assembly including:

a driven shaft rotatable about an axis of rotation;

first and second three-dimensional cam members mounted to said driven shaft for conjoined rotation therewith, said first and second cam members are congruent with respect to one another;

a first pair of followers in contact with said first cam member on opposite sides thereof, said first pair of followers connected to said first fluid displacer and imparting a reciprocating motion on said first fluid displacer during rotation of said driven shaft;

a second pair of followers in contact with said second cam member on opposite sides thereof, said second pair of followers connected to said second fluid displacer and imparting a reciprocating motion on said second fluid displacer during rotation of said driven shaft; and

wherein said first cam member and said second cam member each have a non-cardioid shape cam profile that results in a constant velocity reciprocation motion of said first and second pair of followers during rotation of said driven shaft.

2. The metering pump of claim 1, wherein said first and second pair of followers are longitudinally positional across the cam profile of said first cam member and across the cam profile of said second cam member, respectively, and wherein the longitudinal position of said first and said second pair of followers relative to the cam profile of said first cam member and the cam profile of said second cam member, respectively, varies the stroke length of said first and said second pair of followers between a minimum stroke length and a maximum stroke length.

3. The metering pump of claim 1, further comprising:

a first intermediate shaft connecting said first pair of followers and said first fluid displacer; and

a second intermediate shaft connecting said second pair of followers and said second fluid displacer.

4. The metering pump of claim 3, wherein said first intermediate shaft is split shaft comprising two interconnectable shaft portions; and wherein said second intermediate shaft is a split shaft comprising two interconnectable shaft portion.

5. The metering pump of claim 1, wherein said first and said second fluid displacers are each diaphragms.

6. The metering pump of claim 2, wherein said first and second cam members are mounted to said driven shaft for axial translation along said driven shaft; and

wherein transmission and stroke adjuster assembly further includes:

a stroke adjuster frame supported for translation in a direction along said rotational axis of said driven shaft, said stroke adjuster frame connected to said first and said second cam members for conjoined translational movement therewith, wherein translational movement of said stroke adjuster frame causes an equal translational movement of said first and second cam members along said driven shaft.