Electrically driven compressors and methods for circulating lubrication oil through the same

Abstract

An oil storage area (45a) is defined on the bottom of a motor chamber (45) of a scroll compressor (1). An oil transfer route (4a) is defined in the portion of a center housing (4) that corresponds to the storage area (45a). Lubricating oil L is separated from the discharged, compressed refrigerant by an oil separator (80) and the lubricating oil L is supplied to the rear side of a movable scroll (20) due to a pressure differential within the compressor (1). After lubricating slide contact portions of scroll walls (28, 30) of the fixed and movable scrolls (2, 20), the lubricating oil L is temporarily stored in the storage area (45a) and then is transferred due to a refrigerant pressure differential to the suction-side of a compression mechanism (21) via the oil transfer route (4a). The lubricating oil L is then transferred to the oil separator (80) together with the compressed refrigerant that is discharged from a compression chamber (32) of the compression mechanism (21). Thus, the lubricating oil L contained in the discharged, compressed refrigerant can be effectively separated from the compressed refrigerant and circulated to and from the rear side of the movable scroll (20) in order to lubricate moving parts within the compressor (1) using the refrigerant pressure differentials within the compressor (1).

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to compressors driven by an electric motor as the drive source and methods for lubricating moving parts within the compressors.

[0003] 2. Description of Related Art

[0004] Japanese Laid-open Patent Publication No. 5-313156 discloses a general scroll compressor that is used as a rotary compressor for an air conditioner, refrigerator, or the like. This scroll compressor is configured such that a movable scroll rotates or orbits relative to a fixed scroll in order to compress a refrigerant to a high pressure within a compression chamber defined between the fixed scroll and the movable scroll. The compressed refrigerant is then discharged from a discharge port defined in the fixed scroll.

[0005] In such a scroll compressor, it would be desirable to supply lubricating oil to portions of a fixed scroll wall that slidably contact a movable scroll wall so as to improve the lubrication of the portions that are in sliding contact. However, Japanese Laid-open Patent Publication No. 5-313156 does not suggest any specific technique for supplying lubricating oil to these portions of the fixed scroll wall and the movable scroll wall.

SUMMARY OF THE INVENTION

[0006] Therefore, it is one object of the present teachings to provide techniques for effectively supplying lubrication oil to portions of a scroll type compressor that are in sliding contact. Preferably, the scroll type compressor is driven by an electric motor, which drives a refrigerant compression mechanism that discharges compressed refrigerant through the fixed scroll.

[0007] According to one aspect of the present teachings, scroll type compressors are taught that enable lubrication oil to be readily transferred from a refrigerant discharge side of the compressor to portions of the scroll walls of the fixed and movable scrolls that are in sliding contact by utilizing differences in refrigerant pressure within the compressor.

[0008] According to another aspect of the present teachings, scroll compressors are taught that include a fixed scroll and a movable scroll, each having an opposing scroll wall. A compression chamber may be defined between the opposing walls of the fixed scroll and the movable scroll. The fixed scroll preferably includes a discharge port or discharge region for discharging compressed refrigerant from the compression chamber. An electric motor may drive the movable scroll via a drive shaft, so that the refrigerant is drawn into the compression chamber from a suction side or suction port of the compressor. As the movable scroll rotates or orbits relative to the fixed scroll, the refrigerant is then compressed to generate pressurized refrigerant within the compression chamber and then the compressed or pressurized refrigerant is discharged through the fixed scroll. More specifically, when the movable scroll rotates or orbits relative to the fixed scroll, the respective scroll walls partially slidably contact each other and preferably lubricating oil is reliably supplied to these portions of the scroll walls that are in sliding contact. Further, the motor optionally may be disposed within a substantially sealed motor chamber.

[0009] A refrigerant flow channel may be defined from a suction side or suction port of the compressor through the compression chamber to a discharge side or discharge port of the compressor and the refrigerant preferably flows from the suction side to the discharge side via the refrigerant flow channel. A communication path or passage optionally may be provided to enable the refrigerant flow channel to communicate with the motor chamber. In this case, a so-called “stagnated state” may be created within the motor chamber. Consequently, a portion of the refrigerant moving through the refrigerant flow channel will reach a “stagnated state” within the motor chamber. Moreover, if a pressure difference exists between the refrigerant flow channel and the motor chamber, the refrigerant will move so as to equalize the pressure difference. In this case, heat transfer occurs between the refrigerant within the refrigerant flow channel and the refrigerant within the motor chamber, thereby cooling the electric motor disposed inside the motor chamber. During this process, the amount of refrigerant that serves to cool the electric motor is only a small portion of the total amount of refrigerant that is moving through the refrigerant flow channel. Thus, this technique has little effect on the compression work being performed by the compressor.

[0010] The scroll type compressor may further include a lubricating oil supply route. The lubricating oil supply route may serve to supply lubricating oil, which lubricating oil has been discharged to the discharge area, to the slide contact surfaces of the scroll walls of the fixed and movable scrolls due to difference in pressure between the discharged refrigerant and an area proximal to the slide contact portions. Preferably, the lubricating oil discharged through the fixed scroll may be separated from the compressor refrigerant by an oil separator. Because the pressure of the lubricating oil in the discharged refrigerant is higher than the pressure around the slide contact portions, the lubricating oil in the discharged refrigerant may be easily supplied to the slide contact portions due to this difference in pressure by causing the discharge side region to communicate with the area proximal to the slide contact portions. In addition, the lubricating oil thus supplied to the slide contact portions may be used to improve the lubricating characteristics of the slide contact portions and the sealing performance.

[0011] According to another aspect of the present teachings, the lubricating oil supply route may include a first oil supply route and a second oil supply route. The first oil supply route may supply the lubricating oil to a front side of the movable scroll. Preferably, the first oil supply route may be formed in an end portion of a movable scroll substrate that opposes a fixed scroll substrate. The second oil supply route may transfer the lubricating oil, which has been supplied to the front side of the movable scroll, to the slide contact portions. The first oil supply route and the second oil supply route may be positioned so as to correspond to each other, so that the lubricating oil in the discharge region may be transferred to the slide contact portions via the first and second oil supply routes. Therefore, the supply of the lubricating oil to the slide contact portions may be achieved by the first and second oil supply routes, which may have simple configurations.

[0012] In another aspect of the present teachings, methods for circulating the lubricating oil within electrically driven compressors are taught and may include supplying the lubricating oil, which lubricating oil has been discharged to a discharge area, to the slide contact surfaces of the scroll walls of the fixed and movable scrolls due to difference in pressure between the discharged refrigerant and the area proximal to the slide contact surfaces.

[0013] In another aspect of the present teachings, compressors optionally may include an oil storage area for storing the lubricating oil that has been transferred to the slide contact portions via the lubricating oil supply route. In other words, this oil storage area may be a region or space for storing the lubricating oil that has been used to lubricate the slide contact portions or the excess lubricating oil that has been supplied to the slide contact portions. This oil storage area preferably may be provided, e.g., on the bottom of the motor chamber. In that case, the lubricating oil that has fallen from the slide contact portions toward the bottom of the motor chamber due to gravity can be stored in the oil storage area, which may have a relatively simple configuration. Furthermore, the lubricating oil that has been stored in the oil storage area can be reliably transferred to the suction-side region via a lubricating oil transfer route. Therefore, the lubricating oil can be reliably circulated using a relatively simple configuration.

[0014] In another aspect of the present teachings, methods are taught for circulating lubricating oil through an electrically driven compressor. Such methods may include circulating lubricating oil by supplying the lubricating oil from the discharge-side region of the compressor to the slide contact portions, then transferring the lubricating oil to the suction-side region of the compressor, and finally returning the lubricating oil to the discharge-side region again. These operations may be all performed using the pressure differences in the refrigerant along the refrigerant flow path or route. Therefore, the lubricating oil can be easily circulated using differences in refrigerant pressure.

[0015] Such methods may preferably further include storing the lubricating oil before it is transferred from the bearing mechanism region to the suction-side region. Then, the stored lubricating oil may be transferred from the bearing mechanism region to the suction-side region. Therefore, the lubricating oil can be reliably circulated using such methods.

[0016] Additional objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a vertical cross-sectional diagram of a representative scroll compressor.

[0018] FIG. 2 is a perspective diagram taken along line II-II in FIG. 1.

[0019] FIGS. 3 and 4 are partial cross-sectional diagrams illustrating the relative positions between the first and second oil routes at different rotational positions of a movable scroll.

DETAILED DESCRIPTION OF THE INVENTION

[0020] In one embodiment of the present teachings, electrically driven compressors may include a fixed scroll and a movable scroll that arranged and constructed to draw in a refrigerant (or cooling medium or refrigerant), compress and highly pressurize the refrigerant, and then discharge the pressurized refrigerant via the fixed scroll. The compressor preferably includes a drive shaft, which is coupled to the movable scroll, and an electric motor rotatably driving the drive shaft. The electric motor may be housed within a substantially sealed motor chamber. A bearing may rotatably support the drive shaft. A refrigerant flow channel preferably leads from a suction side of the compressor to a discharge side of the compressor. A communication path (connecting passage) preferably links the refrigerant flow channel to the motor chamber. A lubricating oil supply route may be defined between a discharge-side region of the refrigerant flow channel and portions of the fixed scroll and the movable that slidingly contact each other during operation. Preferably, a difference between the pressure at the discharge-side region of the refrigerant flow channel and at the area proximal to the slide contact portions causes the lubricating oil to be supplied to the slide contact portions via the lubricating oil supply route. A lubricating oil transfer route optionally may be defined between the slide contact portions and a suction-side region of the refrigerant flow channel. Preferably, a difference between the pressure at the area proximal to the slide contact portions and the suction-side region of the compressor causes the lubricating oil, which was previously supplied to the slide contact portions, to be transferred to the suction-side region. Optionally, a storage area may be provided to store lubricating oil that has lubricated the slide contact portions before that lubricating oil is transferred via the lubricating oil transfer route to the suction-side region of the compressor.

[0021] In another embodiment of the present teachings, methods for circulating lubricating oil through electrically driven compressors are taught. Such methods may include supplying lubricating oil to slide contact portions of the fixed scroll and the movable scroll based upon a difference between the pressure at a discharge-side region of a refrigerant flow channel and the pressure at the area proximal to the slide contact portions. Further, the lubricating oil that has lubricated the bearing optionally may be transferred to the suction-side region of the compressor based upon a difference between the pressure at the area proximal to the slide contact portions and the suction-side region. In addition, after transferring the lubricating oil to the suction-side region of the compressor, the lubricating oil optionally may be returned to the discharge-side region of the compressor due to refrigerant compression operation being performed by the compression mechanism. Optionally, after lubricating the slide contact portions, the lubricating oil may be temporarily stored in an oil storage area that is defined proximal to the slide contact portions.

[0022] Each of the additional features and teachings disclosed above and below may be utilized separately or in conjunction with other features and teachings to provide improved compressors and methods for designing and using such compressors. A representative example of the present invention, which example utilizes many of these additional features and teachings both separately and in conjunction, will now be described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the following detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Moreover, various features of the representative example and the dependent claims may be combined in ways that are not specifically enumerated in order to provide additional useful embodiments of the present teachings.

[0023] The representative embodiment of the present teachings will be applied to a scroll compressor that raises the pressure of the introduced refrigerant by compressing it within a compression chamber that is defined between a fixed scroll and a movable scroll. The refrigerant is then discharged as compressed refrigerant. Lubricating oil is compressed with the refrigerant and also discharged with the compressed refrigerant.

[0024] A vertical cross section of the representative electrically driven scroll compressor 1 is shown in FIG. 1. Generally speaking, the compressor 1 includes a fixed scroll member 2, a center housing 4, a front housing 5, and a motor housing 6. These structures generally define the compressor main body. In FIG. 1, the left-side end face of center housing 4 is coupled to the right-side end face of fixed scroll member 2. The motor housing 6 is coupled to the right-side end face of the center housing 4. The front housing 5 is coupled to the left-side end face of the fixed scroll member 2. A drive shaft 8 is rotatably supported by the center housing 4 and the motor housing 6 via radial bearings 10 and 12. An eccentric (or offset) shaft 14, which is eccentric or offset relative to a drive shaft 8, is integrally formed on the end of the drive shaft 8 on the side of the center housing 4 (the left side in FIG. 1).

[0025] A bushing 16 is fitted onto the eccentric shaft 14 so as to integrally rotate with the eccentric shaft 14. A balancing weight 18 is disposed on the right-side end perimeter of the bushing 16, as shown in FIG. 1, so as to integrally rotate with the bushing 16. A movable scroll 20 is supported on the left-side periphery of the bushing 16 by a needle bearing 22 so as to face the fixed scroll 2 and rotate or orbit relative to the fixed scroll 2. The fixed scroll member 2 and the movable scroll 20 basically define a compression mechanism 21 for compressing a refrigerant. The movable scroll 20 has a platter-shaped substrate 24. A cylindrical boss 24a is disposed so as to protrude or project from the right-side surface of this substrate 24, as shown in FIG. 1. The needle bearing 22 and the radial bearing 10 generally define a bearing mechanism 23 of the movable scroll 20.

[0026] The fixed scroll member 2 includes a platter-shaped substrate 26. A spiral-shaped, e.g., involute-shaped, fixed scroll wall (lap) 28 is disposed so as to protrude or project from the right-side surface of this substrate 26, as shown in FIG. 1. Likewise, a spiral-shaped (e.g., involute-shaped) movable scroll wall (lap) 30 is disposed so as to protrude or project from the left-side surface of the substrate 24 of the movable scroll 20, as shown in FIG. 1. These scrolls 2 and 20 are preferably positioned such that the scroll walls 28 and 30 engage each other.

[0027] Thus, the substrate 26 and fixed scroll wall 28 of the fixed scroll 2 together with the substrate 24 and the movable scroll wall 30 of the movable scroll 20 define a crescent-shaped compression chamber (sealed space) 32. More specifically, portions of the fixed scroll wall 28 slidingly contact portions of the movable scroll wall 30 at a plurality of sliding contact areas or points (hereinafter “slide contact portions”). The movable scroll 20 revolves or orbits as the eccentric shaft 14 rotates. During this rotating or orbiting movement, the balancing weight 18 cancels the centrifugal force accompanying the revolution of the movable scroll 20. The eccentric shaft 14 rotates integrally with the drive shaft 8, the bushing 16 and the needle bearing 22, which are disposed between the eccentric shaft 14 and the boss 24a of the movable scroll 20. The eccentric shaft 14 is designed to transmit the rotational force of the drive shaft 8 to the movable scroll 20 as orbiting movement.

[0028] A plurality of (e.g., four) concave areas 34 are defined on the same circumferential line at uniform angular intervals on the left-side end face of the center housing 4, as shown in FIG. 1. A fixed pin 36 is secured to the center housing 4 and a movable pin 38 is secured to the substrate 24 of the movable scroll 20. The fixed pin 36 and the movable pin 38 are inserted into a concave area 34 and fastened. As the eccentric shaft 14 rotates, self-rotation of the movable scroll 20 is prevented by the concave areas 34, fixed pin 36, and movable pin 38. In other words, the concave areas 34, fixed pin 36, and movable pin 38 may define a self-rotation prevention mechanism for the movable scroll 20.

[0029] The substrate 26 of the fixed scroll 2 may include a reed-type discharge valve 52, which opens and closes a discharge opening 50. This discharge valve 52 has a reed valve member 54, which has a shape that corresponds to the discharge opening 50, and a valve retainer 56 for holding or retaining this reed valve member 54. The reed valve member 54 and the valve retainer 56 are secured to the substrate 26 of the fixed scroll 2 by means of a securing bolt 58. The discharge valve 52 is disposed within a discharge chamber 25 partially defined by the substrate 26 of the fixed scroll 2. Preferably, the reed valve member 54 opens and closes according to the difference in pressure between the compression chamber 32, which communicates with the discharge opening 50, and the discharge chamber 25. That is, when the pressure in the compression chamber 32 is higher than the pressure in the discharge chamber 25, the reed valve member 54 opens. Naturally, when the pressure in the compression chamber 32 is lower than the pressure in the discharge chamber 25, the reed valve member 54 closes. The valve retainer 56 is configured to regulate the maximum opening of the reed valve member 54.

[0030] An electric motor 49 is disposed within the motor housing 6. An inverter 60 for controlling the operation of the electric motor 49 is installed on the periphery of the housing of the compressor main body, which essentially consists of the fixed scroll 2, center housing 4, and motor housing 6. The inverter 60 may include, e.g., a switching element 62 that generates a relatively large amount of heat, and a condenser 64 that generates a relatively small amount of heat. The inverter 60 also may include an inverter case 70 for housing these configuration components in order to separate the high and low heat-generating components from each other. The inverter case 70 preferably contains a cylinder 70a, and the switching element 62 may be disposed on the periphery of this cylinder 70a. The inverter case 70 also may include a substrate 65 for installing the condenser 64. The cylinder 70a of inverter case 70 preferably communicates with a suction port 44. One end of the suction port 44 preferably communicates with the fixed scroll 2 while the other end of the suction port 44 preferably communicates with a refrigerant feedback pipe (not shown) of an external circuit.

[0031] The switching element 62 of the inverter case 70 may be electrically coupled to the electric motor 49 by means of three conducting pins 66 (only one of which is shown in the figure) and conductive wires 67 and 68. The conducting pins 66 preferably penetrate into the motor housing 6 and the inverter case 70. Electric current necessary for driving the electric motor 49 is supplied via these conducting pins 66 and conductive wires 67 and 68.

[0032] The location for connecting the conductive wire 68 with the stator coil 46a of the electric motor 49, which will be further described below, is preferably provided on the side of the electric motor 49 that faces the compressor mechanism 21. The inverter 60 is secured to the compressor housing (e.g., the center housing 4 and/or the motor housing 6). The location for connecting the electric motor 49 with the inverter 60 is preferably provided on the periphery of the casing along its diametric direction. In other words, this configuration produces a compact design with a much shorter axial length than a configuration in which the inverter (or a similar device) is disposed on the periphery along the axial direction. Moreover, the location for connecting the electric motor 49 with the inverter 60 is provided such that these components are close to each other. As a result, because the electric motor 49 can be connected to the inverter 60 over the shortest distance possible, a short connection member can be used. Consequently, material cost and weight can be reduced, and performance can be improved by minimizing voltage drops across the connection member.

[0033] A stator 46 is secured to the inner surface of the motor housing 6 and a rotor 48 is secured to the drive shaft 8. The drive shaft 8, stator 46, and rotor 48 generally define the electric motor 49. The stator 46 has a stator coil 46a, and by applying electric current to this stator coil 46a, the rotor 48 and drive shaft 8 rotate together. The electric motor 49 is preferably disposed within a substantially sealed motor chamber 45, which is defined within the motor housing 6 and center housing 4.

[0034] As the eccentric shaft 14 of the drive shaft 8 rotates, the movable scroll 20 revolves (orbits), and the refrigerant introduced from the suction port 44 (which is defined within the fixed scroll 2) flows into the space between the substrate 26 of the fixed scroll 2 and the substrate 24 of the movable scroll 20 from the edge of both scrolls 2 and 20. As the movable scroll 20 revolves, the movable pin 38 slides along the circumferential (peripheral) surface of the fixed pin 36. Then, when the eccentric shaft 14 further rotates, the movable scroll 20, which is installed on said eccentric shaft 14 via the needle bearing 22 so as to be able to rotate relative to the eccentric shaft 14, revolves around the central axis of the drive shaft 8 without rotating itself. As the movable scroll 20 revolves, the refrigerant that has been introduced through the suction port 44 flows into the compression chamber 32 and is guided to the center of the fixed scroll 2 while its pressure increases. Then, the pressurized (compressed) refrigerant flows into the discharge opening 50 that is defined in the center of the substrate 26 of the fixed scroll 2. That is, the discharge opening 50 communicates with the compression chamber 32 where the pressure reaches its highest value.

[0035] The center housing 4, which separates the compression mechanism 21 from the motor chamber 45, preferably includes a connecting passage 47. This connecting passage 47 may serve to connect the suction region within the refrigerant flow channel, which is defined within the compression mechanism 21 and leads from the suction port 44 to the discharge port 86, to the motor chamber 45. In other words, the opening through which the refrigerant enters communicates with the space 47a formed between the peripheral surface of the substrate 24 of the movable scroll 20 and the internal wall surface of the scroll-housing space for housing said substrate 24. The space 47a communicates with the motor chamber 45 via a communication hole 47b, which is defined in the center housing 4. Thus, the space 47a and the communication hole 47b generally define the connecting passage 47.

[0036] While the compressor 1 is operating, the connecting passage 47 always communicates with the refrigerant flow channel regardless of the position of the substrate 24 of the movable scroll 20, which revolves inside the scroll-housing space. Consequently, heat is transferred via the connecting passage 47 between the refrigerant introduced into the refrigerant flow channel and the refrigerant disposed within the motor chamber 45. That is, heat moves from the motor chamber 45, which is at a higher temperature, to the refrigerant flow channel, and this heat transfer cools the electric motor 49. Moreover, when a pressure difference occurs between the motor chamber 45 and the refrigerant suction region, refrigerant will flow between the motor chamber 45 and the suction region via the connecting passage 47 so as to equalize the pressure difference. Therefore, heat is transferred along with this refrigerant flow, and as a result, the electric motor 49 is cooled. Accordingly, the electric motor 49 is prevented from overheating.

[0037] Unlike known methods that utilize the motor chamber as the refrigerant channel, the present cooling methods and apparatus are based on so-called “stagnation cooling,” which is not accompanied by a large refrigerant flow. The introduced refrigerant directly involved in this type of “stagnation cooling” is only a small portion of the total introduced refrigerant flowing through the refrigerant flow channel. Thus, the introduced refrigerant does not significantly raise or increase the temperature of the total introduced refrigerant. Therefore, an increase in the specific volume of the introduced refrigerant can be prevented, thereby eliminating the problem of reduced compression efficiency. Although the present embodiment uses a configuration in which the inverter 60 is cooled by the introduced refrigerant, the amount of heat generated by the inverter 60 is much less compared to the amount of heat that is generated by the electric motor 49. Therefore, the rise in the temperature of the introduced refrigerant caused by cooling the inverter 60 using said introduced refrigerant is small compared to the temperature rise that would be caused by cooling the electric motor 49 if all of the introduced refrigerant is supplied into the motor chamber 45. Therefore, compression efficiency is not reduced.

[0038] Moreover, in the present embodiment, because a low-temperature introduced refrigerant cools the electric motor 49, an improved cooling effect can be obtained than when using discharged refrigerant to cool the electric motor 49. Furthermore, the present configuration, which guides the introduced refrigerant to the motor chamber 45, does not require a sealing material to be disposed around the drive shaft 8, which drive shaft 8 transmits the drive force of the electric motor 49 to the compression mechanism 21. Therefore, a simple structure can be manufactured at a reduced cost.

[0039] The front housing 5 may include an oil separator 80 for separating the lubricating oil within the refrigerant that has been discharged from the discharge chamber 25. This oil separator 80 may utilize, e.g., a separation mechanism that relies upon centrifugal force to perform the oil separation. Thus, the oil separator 80 may generally include an oil separation chamber 81, a cylindrical member 82, a filter 84 installed below the cylindrical member 82, and a storage area (lubricating oil reservoir) 85 for temporarily storing the separated lubricating oil. A connection hole or passage 83 may be defined between the oil separation chamber 81 and the storage area 85 in order to allow lubricating oil to pass from the oil separation chamber 81 to the storage area 85. When the compressed refrigerant discharged from the discharge chamber 25 is introduced into the oil separator 80, as indicated by the curved, solid-line arrow in FIG. 1, the compressed refrigerant collides with the cylindrical member 82 in the oil separation chamber 81 and descends while circling around the cylindrical member 82. Therefore, the lubricating oil contained in the compressed refrigerant will separate due to centrifugal force and the lubrication oil will move, due to gravity, as indicated by the dotted-line arrow shown in FIG. 1.

[0040] Then, after the lubricating oil passes through the connection hole 83 and filter 84, the lubricating oil may be temporarily stored in the storage area 85. Meanwhile, the discharged refrigerant (from which the lubricating oil has been separated) moves from the opening 82a of the cylindrical member 82 to a discharge port 86, and then is transferred to a condenser (not shown) in an external circuit.

[0041] A gasket 90 is preferably disposed between the right end face of the front housing 5 and the left end face of the fixed scroll 2. As shown in FIG. 2, a first oil supply hole 91, which communicates with the storage area 85, is defined near the bottom of this gasket 90, and a second oil supply hole 93 is defined near the top of the gasket 90. The first and second oil supply holes 91, 93 communicate with each other via an oil supply groove (lubricating oil supply passage) 92. A first oil supply route 94 extends from the oil supply hole 93, which is defined at an edge of the fixed scroll substrate 26, to the front side (the left side of the substrate 24 of the movable scroll 20 in FIG. 1) of the movable scroll 20. The first oil supply route 94 preferably has a throttled shape. That is, the area of its oil flow channel is smaller on the side of movable scroll 20 than on the side of the fixed scroll 2. Therefore, it is possible to prevent an unnecessary amount of lubricating oil from being supplied through this first oil supply route 94.

[0042] In addition, as shown in FIGS. 1, 3 and 4, a second oil supply route 95 for communicating lubricating oil may be defined on the front portion of the movable scroll 20 (left side of the movable scroll 20 as viewed in FIG. 1) that corresponds to the first oil supply route 94. The second oil supply route 95 may include a concave area 95a. The second oil supply route 95 may connect the first oil supply route 94 and an area proximal to the slide contact portions of the scroll walls 28 and 30. Therefore, the storage area 85 of the front housing 5 communicates with the area (peripheral area) proximal to the slide contact portions of the scroll walls 28 and 30 via the second oil supply route 95, the oil supply holes 91 and 93, and the lubricating oil supply route, which includes the oil supply groove 92 and the first oil supply route 94.

[0043] Because the second oil supply route 95 is defined on the movable scroll substrate 24, the position of the second oil supply route 95 relative to the first oil supply route 94 changes as the movable scroll 20 rotates. Consequently, the concave area 95a of the second oil supply route 95 may be configured to always communicate with the first oil supply route 94 regardless of the rotational position of the movable scroll 20.

[0044] The storage area 85, which is at the discharge pressure, has a higher pressure than the peripheral area proximal to the slide contact portions. Consequently, the lubricating oil L stored in the storage area 85 is force-fed by the pressure difference to the slide contact portions via the lubricating oil supply route 91-95. The lubricating oil L stored in the storage area 85 will hereinafter be referred to as “the lubricating oil in the discharge-side region.”

[0045] Next, changes in position of the second oil supply route 95 relative to the first oil supply route 94 and resulting changes in the flow of the lubricating oil during this process will be explained with reference to FIGS. 3 and 4.

[0046] The revolving motions of the movable scroll 20 can be expressed as vertical reciprocal movements with respect to FIG. 1. That is, while revolving, the movable scroll 20 is disposed in the position shown in FIG. 3 or FIG. 4. In the position shown in FIG. 3, the first oil supply route 94 communicates with concave area 95a of the second oil supply route 95. However, the lubricating oil L that has entered the concave area 95a may be supplied to the outside of the concave area only through an extremely minute clearance between the fixed scroll 2 and the movable scroll 20. Therefore, the lubricating oil L will not be positively supplied to the slide contact portions of the fixed scroll 2 and the movable scroll 20.

[0047] In the position shown in FIG. 4, the first oil supply route 94 communicates with the concave area 95a of the second oil supply route 95, while a refrigerant flow channel is defined between the fixed scroll 2 and the movable scroll wall 30. Therefore, almost of the lubricating oil, which has been supplied from the first oil supply route 94 to the front side of the movable scroll substrate 24, may be supplied to the slide contact portions of the fixed scroll 2 and the movable scroll 20 via the concave area 95a of the second oil supply route 95. As a result, the lubricating oil can lubricate the slide contact portions and improve sealing performance.

[0048] Meanwhile, a small amount of the lubricating oil that has supplied to the front side of the movable scroll substrate 24 may also be supplied to the back side (right side as viewed in FIG. 1) of the movable scroll 20, so that the lubricating oil can lubricate the bearing mechanism 23. The lubricating oil may then fall due to gravity from the bearing mechanism 23 and may be stored in a storage area 45a (concave area) formed on the bottom of the motor chamber 45.

[0049] A transfer route 4a (hereinafter referred to as “the lubricating oil transfer route”) may preferably defined in the lower portion (one location) of the center housing 4, which corresponds to the storage area 45a. This transfer route 4a links the storage area 45a of the motor chamber 45 to the suction region (hereafter also referred to as “the suction-side region”) of the compression mechanism 21. When the lubricating oil in the storage area 85 is being supplied to the rear side of the movable scroll 20, a portion of the discharged refrigerant is also carried along through the lubricating oil supply route 91-95. Consequently, the pressure in the storage area 45a becomes higher than the pressure in the suction region, which is at the introduced refrigerant pressure. Lubricating oil L that has lubricated the slide contact portions of the fixed and movable scrolls 2, 20 may fall into the storage area 45a for temporary storage.

[0050] Thereafter, the lubricating oil L, which has been temporarily stored in the storage area 45a, is transferred by the pressure difference to the suction side region or the suction port 44 of the compression mechanism 21 via the transfer route 4a. Then, this lubricating oil L is transferred from the discharge opening 50 to the oil separator 80, together with the refrigerant that has been highly pressurized in the compression chamber 32, and is discharged. Thus, in the above representative embodiment, the first oil supply hole 91 may serve as a first end of the lubricating oil supply route 91-95, which first end communicates with the discharge port 86 (the discharge side region), while the second oil supply route 95 may serve as a second end of the lubricating oil supply route 91-95, which second end communicates with the suction port 44 (the suction side region). The lubricating oil L contained in the discharged refrigerant is again separated by the oil separator 80 and force-fed to the rear side of the movable scroll 20 via the lubricating oil supply route 91-95. In this way, the lubricating oil contained in the discharged refrigerant is circulated to and from the rear side of the movable scroll 20. The capacity of the storage area 45a and the size of the flow channel area of the transfer route 4a, etc. can be appropriately set according to the volume of lubricating oil L that will be stored in the storage area 45a.

[0051] In the scroll compressor having the above-described configuration, when the electric motor 49 is driven, the refrigerant returning from the evaporator (not shown) of an external circuit is guided into the compressor 1 via the cylinder 70a and suction port 44. During this process, the refrigerant passing through the cylinder 70a cools the inverter 60. Then, this refrigerant is highly pressurized in the compression chamber 32 as the movable scroll 20 revolves, and is then transferred as discharged refrigerant to the condenser (not shown) of an external circuit from the discharge port 86.

[0052] As described above, the lubrication oil L may be rationally used for lubrication, because the lubricating oil L has been separated from discharged refrigerant at the discharge region by means of the oil separator 80. Moreover, the lubricating oil L can be readily transferred within the compressor 1 by utilizing pressure differences of the refrigerant disposed within the compressor 1. Furthermore, because the lubricating oil L is supplied to the slide contact portions of the scroll walls 28 and 29 of the fixed and movable scrolls 2 and 20, respectively, via the lubricating oil supply route (i.e., the oil supply holes 91 and 93, oil supply groove 92, first oil supply route 94, and second oil supply route 95), the lubricating characteristics and durability of the bearing mechanism 23 can be improved.

[0053] The present invention is not limited to the above embodiment, and various kinds of applications and modifications are possible. For example, the above embodiment modified in the following ways:

[0054] (A) In the above representative embodiment, the lubricating oil L that has been separated from the discharged refrigerant by the oil separator 80 is supplied to the slide contact portions of the scroll walls 28, 30 of the fixed and movable scrolls 2, 20. However, it is also possible to use, for example, a configuration in which the lubricating oil L stored in a storage area, which is different from the oil separator 80, is supplied to the slide contact portions using the difference in pressure between the discharged refrigerant and the region proximal to the slide contact portions.

[0055] (B) In the above representative embodiment, the second oil supply route 95 is defined within the movable scroll 20. However, the oil supply route 95 may be defined in the fixed scroll 2 in a position corresponding to the first oil supply route 94.

Claims

1. A scroll compressor comprising:

a fixed scroll and a movable scroll having respective scroll walls, the scroll walls slidably contacting each other and defining a compression chamber between the fixed scroll and the movable scroll,

an electric motor rotatably driving the movable scroll, whereby a refrigerant is drawn from a suction-side region, is compressed within the compression chamber and is then discharged to a discharge-side region as the movable scroll rotates relative to the fixed scroll, wherein a refrigerant flow channel is defined from the suction side region to the discharge side region via the compression chamber,

a motor housing defining a substantially sealed motor chamber, wherein the electric motor is disposed within the motor chamber,

a communication path linking the refrigerant flow channel to the motor chamber and

a lubricating oil supply route defined between a discharge-side region of the refrigerant flow channel and an area proximal to slide contact portions of the scroll walls of the fixed and movable scrolls, the lubricating oil supply route being arranged and constructed so that a difference between the pressure at the discharge-side region of the refrigerant flow channel and the pressure at the area proximal to the slide contact portions of the scroll walls of the fixed and movable scrolls urges lubricating oil towards the slide contact portions of the scroll walls of the fixed and movable scrolls via the lubricating oil supply route.

2. A scroll compressor as in claim 1, wherein the lubricating oil supply route includes a first oil supply route and a second oil supply route, the first oil supply route supplying the lubricating oil to a front side of the movable scroll, and the second oil supply route communicating with the front side of the movable scroll and extending to the slide contact portions.

3. A method for circulating lubricating oil through an electric compressor having a fixed scroll and a movable scroll with respective scroll walls that slidably contact with each other and define a compression chamber between the fixed scroll and the movable scroll, wherein a refrigerant flow channel is defined between a suction-side region and a discharge-side region, and a lubricating oil supply route is defined between the discharge-side region of the refrigerant flow channel and the area proximal to slide contact portions of the scroll walls of the fixed and movable scrolls, comprising:

pressure-feeding lubricating oil to the slide contact portions of the scroll walls of the fixed and movable scrolls via the lubricating oil supply route based upon a difference between the pressure at the discharge-side region of the refrigerant flow channel and the pressure at the area proximal to the slide contact portions of the scroll walls of the fixed and movable scrolls.

4. A method as in claim 3, wherein the lubricating oil supply route includes a first oil supply route and a second oil supply route, the method further comprising supplying lubricating oil via the first oil supply route to a front side of the movable scroll, and supplying lubricating oil via the second oil supply route to the slide contact portions of the scroll walls of the fixed and movable scrolls.

5. A scroll compressor comprising:

a compressor having a fixed scroll and a movable scroll, the movable scroll coupled to a drive shaft, wherein a discharge-side region is disposed in communication with the fixed scroll,

an electric motor rotatably driving the drive shaft, and

a lubricating oil route arranged and constructed to transfer lubrication oil from the discharge-side region to slide contact portions of the fixed and movable scrolls via the lubricating oil supply route so as to lubricate the slide contact portions as the refrigerant is compressed by the compressor.

6. A scroll compressor as in claim 5, wherein the lubricating oil route has a first end and a second end that respectively communicate with the discharge-side region and a suction-side region of the compressor, wherein the lubricating oil route is arranged and constructed so that the lubrication oil flows from the discharge-side region to the slide contact portions of the fixed and movable scrolls due to a difference in pressure between refrigerant pressure at the discharge-side region and refrigerant pressure at an area proximal to the slide contact portions of the fixed and movable scrolls.

7. A scroll compressor as in claim 6, further including an oil separator communicating with the discharge-side region, the oil separator being arranged and constructed to separate the lubricating oil from compressed refrigerant that has been discharged from the compression chamber.

8. A method for circulating lubricating oil within an electrically driven scroll compressor driven by an electric motor, the method comprising:

generating a pressure differential between a discharge-side region of the compressor and slide contact portions of the compressor, thereby causing lubricating oil to move via a lubricating oil route from the discharge-side region to the slide contact portions.

9. A method as in claim 8, wherein the pressure differential along the lubricating oil route is generated due to refrigerant that is compressed by the compressor.

10. A method as in claim 9, wherein a first end of the lubricating oil route communicates with the discharge-side region and a second end of the lubricating oil route communicates with a suction port, the method further comprising forcing the lubrication oil from the discharge-side region to the area proximal to the slide contact portions due to a difference in refrigerant pressure between the discharge-side region and the area proximal to the slide contact portions.

11. An method as in claim 10, further comprising pressure-feeding the lubricating oil via a lubricating oil transfer route defined between the area proximal to the slide contact portions and the suction-side region of the compressor due to a difference between the refrigerant pressure at the area proximal to the slide contact portions and the suction-side region of the compressor.

12. A method as in claim 11, further including separating the lubricating oil from compressed refrigerant that has been discharged from a compression chamber of the compressor.

13. A method as in claim 12, further including storing the lubricating oil that lubricated the slide contact portions before the stored lubricating oil is transferred to the suction-side region.

14. A method for circulating lubricating oil within an electrically driven scroll compressor, comprising:

separating lubricating oil from compressed refrigerant in an area proximal to and communicating with a discharge port of the compressor, and

transferring the separated lubricating oil to slide contact portions of scroll walls of fixed and movable scrolls via a lubricating oil supply route using a refrigerant pressure-differential between the area proximal to and communicating with the discharge port and an area proximal to the slide contact portions of the scroll walls of the fixed and movable scrolls, wherein the slide contact portions are lubricated with the lubricating oil.

15. An electrically driven scroll compressor, comprising:

means for separating lubricating oil from compressed refrigerant in an area proximal to and communicating with a discharge port of the compressor, and

means for transferring the separated lubricating oil to slide contact portions of scroll walls of fixed and movable scrolls using a refrigerant pressure-differential between the area proximal to and communicating with the discharge port and an area proximal to the slide contact portions of the scroll walls of the fixed and movable scrolls, whereby the slide contact portions are lubricated with the lubricating oil.