Variable displacement compressor

Abstract

[Problem] To provide a variable displacement compressor capable of smoothly supplying oil to a thrust receiving part, a lip seal, and a bush. [Solution] The present invention comprises: a drive shaft 7 which passes through a crank chamber C1 and is rotatably supported in a housing 5 through a bush 21, and of which one end protrudes from the housing 5; a thrust receiving part 31 for receiving thrust force from a piston 12; a lip seal 17 which provides sealing between the drive shaft 7 and the housing 5; and an oil supply passage 302 communicating with the crank chamber C1 and a seal space 301. The thrust receiving part 31 has a plurality of thrust races 312, 311C combined in layers. The oil supply passage 302 has a shape that is narrower toward the seal space 301.

Description

Variable displacement compressor

[0001] The present invention relates to a variable displacement compressor used to compress a refrigerant in, for example, an air conditioning system for a vehicle.

[0002] Variable displacement compressors, which include so-called wobble plate compressors and swash plate compressors, are configured to suck in and compress refrigerant by converting the rotation of a swash plate rotated by a drive shaft into the reciprocating motion of pistons in cylinder bores (see, for example, Patent Document 1).

[0003] The compressor described in Patent Document 1 is a wobble plate type compressor, which includes a rotor that rotates integrally with the drive shaft within a housing, a swash plate that rotates with the rotation of the rotor, and a wobble plate that oscillates with the rotation of the swash plate, causing the pistons to move back and forth.The compressor is configured so that the inclination angle (tilt angle) of the swash plate relative to the drive shaft can be changed to change the oscillation width of the wobble plate, thereby changing the stroke amount of the pistons and changing the discharge capacity.

[0004] In this case, the thrust force from the piston side is received by a thrust receiving portion provided between the rotor and the front housing.

[0005] The drive shaft is rotatably supported in the housing via a bushing, and a lip seal seals the gap between the drive shaft and the housing. In this case, the thrust bearing part may slide and rotate on the housing as the drive shaft rotates, so it requires oil lubrication. The sliding parts between the bushing, lip seal, and drive shaft also require oil lubrication.

[0006] To address this issue, conventional designs have included an oil supply passage within the housing, which supplies oil (refrigerant and oil) from the crankcase to the sealed space between the bushing and the lip seal. In this configuration, the oil supplied by gravity from the oil supply passage to the sealed space between the bushing and the lip seal is supplied to the lip seal to lubricate it, and also soaks into the bushing to lubricate it. The oil then circulates through the thrust receiving section before returning to the crankcase (see, for example, Patent Documents 2 and 3).

[0007] JP 2024-14498 A WO2018 / 207724 JP 2018-155211 A

[0008] However, the oil supplied to the lip seal by gravity had difficulty returning to the crankcase due to the narrow clearance of the bushing, which resulted in a blockage in the oil circulation from the crankcase through the oil supply passage, lip seal, bushing, and thrust receiving section, and then back into the crankcase, causing heat generation in the sliding parts.

[0009] Furthermore, since oil does not flow from the lip seal into the crank chamber, an oil supply shortage occurs, which accelerates wear of the lip seal due to poor lubrication and makes refrigerant leaks more likely.

[0010] The present invention has been made to solve the above-mentioned conventional technical problems, and has an object to provide a variable displacement compressor that can smoothly supply oil to the thrust receiving portion, lip seal, and bushing.

[0011] In order to solve the above problems, the variable displacement compressor of the present invention includes a housing having a cylinder bore and a crank chamber therein, pistons arranged in the cylinder bores, a drive shaft that penetrates the crank chamber and is rotatably supported on the housing via a bushing, with one end protruding from the housing, a rotor that rotates integrally with the drive shaft, a swash plate that rotates with the rotation of the rotor, a conversion mechanism that converts the rotation of the swash plate into reciprocating motion of the pistons, a thrust receiving portion that is provided between the housing and the rotor and receives a thrust force from the piston side, a lip seal that is arranged closer to one end of the drive shaft than the bushing and seals between the drive shaft and the housing, and an oil supply passage that is formed in the housing and has one end communicating with the crank chamber and the other end communicating with a seal space between the bushing and the lip seal, and is characterized in that the thrust receiving portion has a plurality of thrust races combined in layers, and the oil supply passage has a shape that is narrowed on the seal space side.

[0012] A variable displacement compressor according to a second aspect of the present invention is characterized in that in the above-mentioned invention, the thrust bearing comprises a thrust rolling bearing and a first annular thrust race provided on the housing side of the thrust rolling bearing, the thrust rolling bearing has a plurality of rolling elements and second and third annular thrust races sandwiching the rolling elements from the housing side and the rotor side, and the first thrust race and second thrust race are combined in layers.

[0013] A variable displacement compressor according to a third aspect of the present invention is characterized in that, in the first aspect of the present invention, the oil supply passage has a diameter that is reduced in a stepped manner on the sealing space side.

[0014] The variable displacement compressor of the invention of claim 4 is characterized in that in each of the above inventions, the oil supply passage has a shape in which the inlet on the crank chamber side is gradually widened.

[0015] In a variable displacement compressor according to a fifth aspect of the present invention, the inlet of the oil supply passage in the above-mentioned invention opens into the crank chamber vertically above the thrust receiving portion.

[0016] According to the present invention, a variable displacement compressor includes a housing having a cylinder bore and a crank chamber therein, a piston disposed in the cylinder bore, a drive shaft that penetrates the crank chamber and is rotatably supported on the housing via a bushing, with one end protruding from the housing, a rotor that rotates integrally with the drive shaft, a swash plate that rotates with the rotation of the rotor, a conversion mechanism that converts the rotation of the swash plate into reciprocating motion of the pistons, a thrust receiving portion that is provided between the housing and the rotor and receives thrust force from the piston side, a lip seal that is located closer to one end of the drive shaft than the bushing and seals between the drive shaft and the housing, and an oil supply passage formed in the housing, one end of which communicates with the crank chamber and the other end of which communicates with a seal space between the bushing and the lip seal, and the thrust receiving portion is provided with a plurality of thrust races combined in layers, and the oil supply passage is shaped so that the seal space side is narrowed, so that the oil flow rate is slow at the inlet side of the oil supply path and the flow rate is faster at the narrowed portion.

[0017] The multiple thrust races, arranged in layers, rotate as the drive shaft rotates, acting as a Tesla pump. As a result, oil taken into the oil supply passage from the crankcase increases in flow velocity at the throttle point and flows into the seal space between the bushing and lip seal. The pumping effect of the rotating multiple thrust races then draws the oil into the bushing, passing through the thrust receiving section and returning to the crankcase.

[0018] This promotes the supply of oil to the lip seal, as well as to the bushing, and further promotes the supply of oil to the thrust receiving portion, so that these can be lubricated without any problems and the generation of sludge can be suppressed.

[0019] In this case, the thrust bearing is specifically composed of a thrust rolling bearing and an annular first thrust race provided on the housing side of the thrust rolling bearing, as in claim 2. The thrust rolling bearing has a plurality of rolling elements and annular second and third thrust races sandwiching the rolling elements from the housing side and the rotor side, with the first thrust race and second thrust race combined in layers.

[0020] Furthermore, by forming the oil supply passage in a shape in which the diameter is reduced stepwise on the sealing space side as in the third aspect of the invention, the oil flow velocity can be increased more effectively.

[0021] Furthermore, if the oil supply passage is shaped so that the entrance on the crank chamber side gradually widens as in the fourth aspect of the invention, oil can be smoothly taken in from the crank chamber to the oil supply passage.

[0022] Furthermore, if the inlet of the oil supply passage is designed to open into the crank chamber vertically above the thrust receiving portion as in the invention of claim 5, interference with the thrust receiving portion can be avoided and oil can flow smoothly from the crank chamber into the oil supply passage by gravity.

[0023] 1 is a cross-sectional view of a variable displacement compressor according to an embodiment of the present invention; FIG. 2 is a cross-sectional view of a front housing portion of the variable displacement compressor of FIG. 1; FIG. 3 is a diagram illustrating the flow of refrigerant and oil from an oil supply passage to a thrust receiving portion of the variable displacement compressor of FIG. 1; and FIG. 4 is a diagram illustrating the weight of oil drawn into the oil supply passage in the variable displacement compressor of FIG.

[0024] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a cross-sectional view of a variable displacement compressor 1 according to an embodiment of the present invention. The variable displacement compressor 1 of the embodiment is a so-called wobble plate compressor, and is primarily used in vehicle air conditioning systems. The left side of Fig. 1 is the front side of the variable displacement compressor 1, and the right side is the rear side of the variable displacement compressor 1.

[0025] The variable displacement compressor 1 has a generally cylindrical shape overall. Referring to Fig. 1, the variable displacement compressor 1 includes a cylinder block 2 having a plurality of cylinder bores 2A (one of which is shown in Fig. 1), a front housing 3 provided at one end (left side in Fig. 1) of the cylinder block 2, and a cylinder head 4 provided at the other end (right side in Fig. 1) of the cylinder block 2. The plurality of cylinder bores 2A are arranged in an annular shape when viewed from the front side. The cylinder block 2, front housing 3, and cylinder head 4 are joined together with fastening bolts or the like to form a housing 5 of the variable displacement compressor 1. A valve plate 6 is disposed between the cylinder block 2 and the cylinder head 4.

[0026] A crank chamber C1 is provided within the housing 5. The crank chamber C1 is defined by the cylinder block 2 and the front housing 3. The crank chamber C1 communicates with each of the cylinder bores 2A. A suction chamber C2 and a discharge chamber C3 are also formed in the cylinder head 4. Thus, the housing 5 has a plurality of cylinder bores 2A, the crank chamber C1, the suction chamber C2, and the discharge chamber C3 inside.

[0027] The suction chamber C2 communicates with each cylinder bore 2A via a suction hole 61 formed in the valve plate 6. The suction hole 61 is opened and closed by a suction valve (not shown) which is a reed valve. The suction chamber C2 is also connected to the low-pressure side of the refrigerant circuit of the vehicle air conditioning system via a suction passage (not shown).

[0028] The discharge chamber C3 communicates with the cylinder bore 2A via a discharge hole 62 formed in the valve plate 6. The discharge hole 62 is opened and closed by a discharge valve 63, which is a reed valve. The discharge chamber C3 is also connected to the high-pressure side of the refrigerant circuit of the vehicle air conditioning system via a discharge passage (not shown).

[0029] The variable displacement compressor 1 has a drive shaft 7 to which a rotational driving force is input from an external drive source. The drive shaft 7 extends through a crank chamber C1 from the front side to the rear side. A rotor 8, a swash plate 9, and a wobble plate 10 are arranged in the crank chamber C1 from the front side to the rear side.

[0030] The rotor 8 is fixed to the drive shaft 7. That is, the drive shaft 7 and the rotor 8 are integrated. The drive shaft 7 and the rotor 8 are rotatably supported in the radial direction by a bush 21 (first radial bearing) and a bush 22 (second radial bearing) in the housing 5. The bush 21 is attached to the front housing 3, and the bush 22 is attached to the cylinder block 2. That is, the drive shaft 7 is rotatably supported in the housing 5 via the bush 21 and the bush 22, and the rotor 8 rotates integrally with the drive shaft 7. In this embodiment, the bushes 21 and 22 are configured as sliding bearings.

[0031] The drive shaft 7 and the rotor 8 are supported in the thrust direction by a thrust bearing 31 (first thrust bearing) and a thrust bearing 32 (second thrust bearing). The thrust bearing 31 is provided between the front housing 3 and the rotor 8, and the thrust bearing 32 is attached to the cylinder block 2.

[0032] The swash plate 9 is generally disk-shaped and has a boss 9A protruding toward the rear at its approximate center. The swash plate 9 rotates with the rotation of the drive shaft 7 and the rotor 8. The inclination angle of the swash plate 9 relative to the axis of the drive shaft 7 is adjustable.

[0033] Specifically, the swash plate 9 is connected to the rotor 8 via a connecting mechanism (link mechanism) 11. The connecting mechanism 11 is composed of a swash plate-side arm 111 protruding from the swash plate 9, a rotor-side arm 113 protruding from the rotor 8, and a connecting pin 112 fixed to the rotor-side arm 113. The swash plate-side arm 111 has an arc-shaped hole 111A formed therein, into which the connecting pin 112 is movably inserted.

[0034] An insertion hole 9B, through which the drive shaft 7 is inserted, is formed in the approximate center of the swash plate 9. The insertion hole 9B is shaped to allow the swash plate 9 to move in the axial direction of the drive shaft 7 and to change the inclination angle of the swash plate 9 relative to the axis of the drive shaft 7 within a predetermined range.

[0035] In this embodiment, the swash plate 9 is configured to be changeable between the state shown in FIG. 1 (hereinafter referred to as the "first state") and a state (hereinafter referred to as the "second state") in which it is positioned more rearward than the state shown in FIG. 1 and is substantially perpendicular to the drive shaft 7.

[0036] The wobble plate 10 is generally ring-shaped and oscillates in response to the rotation of the swash plate 9, causing the pistons 12 disposed in the cylinder bores 2A to reciprocate. That is, the wobble plate 10 functions as a conversion mechanism that converts the rotation of the swash plate 9 into the reciprocating motion of the pistons 12.

[0037] Specifically, the inner peripheral surface of the wobble plate 10 is attached to the outer peripheral surface of the boss 9A of the swash plate 9 via a third radial bearing 41. A thrust bearing 42 is disposed between the rear surface of the swash plate 9 and the front surface of the wobble plate 10. A balance ring 13 is fixed to the tip end of the boss 9A of the swash plate 9 with a predetermined gap between it and the wobble plate 10. The balance ring 13 is a component primarily used to dynamically balance the swash plate 9. The swash plate 9, wobble plate 10, and balance ring 13 are integrated together such that the wobble plate 10 can rotate relative to them.

[0038] Rotation of the rocker plate 10 is prevented by an extension 10A extending downward from the rocker plate 10 and a rail member (rotation preventing member) 14 provided in the lower part of the crank chamber C1 and extending from the front side to the rear side.

[0039] The wobble plate 10 is connected via a connecting rod 15 to a piston 12 that is arranged in each cylinder bore 2A so as to be capable of reciprocating motion.

[0040] As a result, the wobble plate 10 is configured to oscillate in the axial direction of the drive shaft 7 as the swash plate 9 rotates, causing the pistons 12 to reciprocate within the cylinder bores 2A via the connecting rods 15. Therefore, when the swash plate 9 (and the wobble plate 10) is in the second state, substantially perpendicular to the drive shaft 7, the wobble plate 10 has a small oscillation amplitude and the pistons 12 have a small stroke. On the other hand, when the swash plate 9 (and the wobble plate 10) is in the first state shown in FIG. 1, the wobble plate 10 has a large oscillation amplitude and the pistons 12 have a large stroke.

[0041] The front side of the drive shaft 7 extends through the boss portion 3A of the front housing 3, and the front end of the drive shaft 7 is located outside the housing 5. An electromagnetic clutch 16 is attached to the boss portion 3A of the front housing 3. In the variable displacement compressor 1 according to the embodiment, when the electromagnetic clutch 16 is engaged, a rotational driving force from an external driving source is input to the front end of the drive shaft 7, thereby rotating the drive shaft 7 (and the rotor 8). A lip seal 17 (shaft sealing device) is attached to the boss portion 3A, isolating the inside and outside of the housing 5.

[0042] The variable displacement compressor 1 further includes a control valve 18. The control valve 18 is configured to control the amount of refrigerant pressure in the crank chamber C1 that is released to the suction chamber C2 by adjusting the opening of a pressure relief passage that connects the crank chamber C1 and the suction chamber C2. In this embodiment, the control valve 18 is attached to the cylinder block 2, and the pressure relief passage includes a passage (internal passage, not shown) formed inside the drive shaft 7. The discharge chamber C3 and the crank chamber C1 are also connected via a pressure supply passage, not shown, that has a throttle portion.

[0043] The operation of the variable displacement compressor 1 will now be described. When the drive shaft 7 and rotor 8 are rotated by a rotary driving force from an external drive source, the swash plate 9 rotates, and the rotation of the swash plate 9 causes the wobble plate 10 to swing in the axial direction of the drive shaft 7. This causes the pistons 12, connected to the wobble plate 10 via connecting rods 15, to reciprocate within the corresponding cylinder bores 2A. Refrigerant from the refrigerant circuit is introduced into the suction chamber C2 via the suction passage. As the pistons 12 reciprocate, the refrigerant in the suction chamber C2 is drawn into the cylinder bores 2A via the suction holes 61 and the suction valves and compressed. The compressed refrigerant is discharged into the discharge chamber C3 via the discharge hole 62 and the discharge valve 63. The refrigerant (high-pressure refrigerant) discharged into the discharge chamber C3 is then discharged into the refrigerant circuit via the discharge passage.

[0044] When the control valve 18 closes, the pressure relief passage, which allows refrigerant in the crank chamber C1 to flow into the suction chamber C2, is blocked. Furthermore, the high-pressure refrigerant in the discharge chamber C3 is supplied to the crank chamber C1 through the pressure supply passage having the throttle portion. This increases the pressure in the crank chamber C1. When the pressure in the crank chamber C1 becomes higher than the pressure in the suction chamber C2, the swash plate 9 and the wobble plate 10 move toward the rear and approach the second state in which they are substantially perpendicular to the drive shaft 7. This reduces the oscillation amplitude of the wobble plate 10, shortening the stroke of the pistons 12 and reducing the discharge capacity of the variable displacement compressor 1.

[0045] On the other hand, when the control valve 18 opens, the refrigerant in the crank chamber C1 flows into the suction chamber C2 through the pressure relief passage. The high-pressure refrigerant in the discharge chamber C3 is supplied to the crank chamber C1 through the pressure supply passage having the throttle portion. However, the flow rate of the high-pressure refrigerant through the pressure relief passage is greater than the flow rate of the high-pressure refrigerant in the discharge chamber C3. As a result, the pressure in the crank chamber C1 drops. When the pressure in the crank chamber C1 drops below the pressure in the suction chamber C2, the swash plate 9 and the wobble plate 10 move toward the front and approach the first state shown in FIG. 1. This increases the amplitude of the wobble plate 10, increasing the stroke of the pistons 12 and the discharge capacity of the variable displacement compressor 1.

[0046] In the variable displacement compressor 1 of the embodiment, the thrust force from the piston 12 side is received by the thrust receiving portion 31 provided between the front housing 3 and the rotor 8. The thrust force from the piston 12 side is mainly a compression reaction force acting on the piston 12. Therefore, if the lubrication of the thrust receiving portion 31 is impaired, friction loss and heat generation may increase.

[0047] Furthermore, because the lip seal 17 and bushing 21 are in sliding contact with the rotating drive shaft 7, poor lubrication of the lip seal 17 and bushing 21 increases friction loss and heat generation, and also leads to the generation of sludge. Furthermore, lack of lubrication of the lip seal 17 accelerates wear, leading to the problem of increased refrigerant leakage.

[0048] In order to solve or mitigate such problems, the variable displacement compressor 1 of the present invention employs the following configuration, which will be described with reference to Figures 2 to 4. Figure 2 shows an enlarged view of the front housing 3 and the thrust bearing portion 31 of the variable displacement compressor 1.

[0049] In the variable displacement compressor 1 of the embodiment, the thrust bearing 31 that receives the thrust force from the piston 12 side is composed of a thrust rolling bearing 311 arranged on the rotor 8 side and a first thrust race 312 provided on the front housing 3 (housing 5) side, and the thrust rolling bearing 311 and the first thrust race 312 are attached to the drive shaft 7.

[0050] The thrust rolling bearing 311 has a plurality of rolling elements 311A, an annular cage 311B that holds the plurality of rolling elements 311A ​​at intervals in the circumferential direction, and annular plate-shaped second thrust race 311C and third thrust race 311D that sandwich the plurality of rolling elements 311A ​​from the front housing 3 (housing 5) side and the rotor 8 side. The second thrust race 311C and the third thrust race 311D are common parts.

[0051] The thrust rolling bearing 311 is disposed so that the third thrust race 311D is located on the rotor 8 side, and is supported by its inner diameter in contact with the outer diameter of the drive shaft 7. In other words, because the thrust rolling bearing 311 is supported by the drive shaft 7, the thrust rolling bearing 311 is in a state in which it can easily rotate with the drive shaft 7. The rotor 8 is formed with a flat surface 8A with which the outer surface of the third thrust race 311D comes into contact. The flat surface 8A is approximately the same size as or larger than the outer surface of the third thrust race 311D.

[0052] The first thrust race 312 is also formed in the shape of an annular plate. The first thrust race 312 is disposed between the second thrust race 311C of the thrust rolling bearing 311 and the front housing 3, and is supported by its inner diameter in contact with the outer diameter of the drive shaft 7. That is, the first thrust race 312 is also supported by the drive shaft 7, and therefore the first thrust race 312 is also easily rotated by the drive shaft 7.

[0053] The first thrust race 312 is formed to have approximately the same radial dimension as the second thrust race 311C (and the third thrust race 311D) of the thrust rolling bearing 311. The first thrust race 312 is combined in a layered manner with the second thrust race 311C of the thrust rolling bearing 311 to form a so-called Tesla pump that utilizes the boundary layer effect.

[0054] One surface (rear surface) of the first thrust race 312 is located on the thrust rolling bearing 311 (second thrust race 311C) side, and the other surface (front surface) of the first thrust race 312 is located on the front housing 3. A seating surface 3B with which the other surface of the first thrust race 312 comes into contact is formed on the front housing 3. The seating surface 3B is formed as a flat surface with approximately the same area as or larger than the other surface of the first thrust race 312.

[0055] In the variable displacement compressor 1, when a thrust force is generated from the piston 12 side, the flat surface 8A of the rotor 8 comes into contact with the outer surface of the third thrust race 311D of the thrust rolling bearing 311, the outer surface of the second thrust race 311C of the thrust rolling bearing 311 comes into contact with one surface of the first thrust race 312, and the other surface of the first thrust race 312 comes into contact with the seating surface 3B of the front housing 3. Then, the entire first thrust receiving portion 31 is pressed against the seating surface 3B of the front housing 3.

[0056] An oil supply passage 302 is formed in the front housing 3, which connects a seal space 301 between the bushing 21 and the lip seal 17 with the crank chamber C1. An inlet 302A at one end of this oil supply passage 302 opens into the crank chamber C1 vertically above the thrust receiving portion 31, and is inclined obliquely downward from this end, and an outlet 302B at the other end opens into the seal space 301 between the bushing 21 and the lip seal 17 described above.

[0057] 3, the oil supply passage 302 has an inlet 302A on the crank chamber C1 side that gradually widens toward the crank chamber C1. The oil supply passage 302 has a stepped diameter reduction (narrowing diameter) on the seal space 301 side to form a narrow diameter portion 302C. As a result, the oil supply passage 302 has a narrowed shape on the seal space 301 side.

[0058] With the above configuration, how the refrigerant (gas refrigerant) and oil in the crank chamber C1 flow through the oil supply passage 302 to the thrust bearing 31 will now be described with reference to Figure 3. As described above, the first thrust race 312 is combined in layers with the second thrust race 311C of the thrust rolling bearing 311 to form a so-called Tesla pump. When the first thrust race 312 and the second thrust race 311C rotate in conjunction with the rotation of the drive shaft 7, rotational energy is imparted to the oil by friction between the first thrust race 312 and the second thrust race 311C. As a result, the oil is sucked in from the axial direction (thrust direction), taken into the central portions of the first thrust race 312 and the second thrust race 311C, and then discharged toward the outer periphery in the radial direction (pumping action).

[0059] Due to the negative pressure at this time, the refrigerant (gas refrigerant) and oil in the crank chamber C1 are sucked into the oil supply passage 302 from the inlet 302A of the oil supply passage 302 as shown by the arrow in Figure 3, and flow down through the oil supply passage 302 by gravity. At this time, the inlet 302A of the oil supply passage 302 has a shape that gradually widens toward the crank chamber C1, so that the refrigerant and oil are smoothly taken into the oil supply passage 302 from the crank chamber C1.

[0060] In addition, the oil supply passage 302 has a narrowed diameter portion 302C on the sealing space 301 side, so the flow rate of the refrigerant and oil is slow on the inlet 302A side of the oil supply passage 302 and increases in the narrowed diameter portion 302C, before flowing into the sealing space 301 between the bushing 21 and the lip seal 17. The oil that has flowed into this sealing space 301 lubricates the sliding portion between the lip seal 17 and the drive shaft 7.

[0061] The refrigerant and oil in the seal space 301 are drawn toward the bushing 21 by the pumping effect of the rotating first thrust race 312 and second thrust race 311C. The oil drawn toward the bushing 21 lubricates the sliding portion between the bushing 21 and the drive shaft 7. The refrigerant and oil that flow into the bushing 21 enter the thrust bearing portion 31 from the axial direction by the pumping effect of the first thrust race 312 and second thrust race 311C, lubricates the sliding portion between the first thrust race 312 and the seat surface 3B of the front housing 3 and the inside of the thrust rolling bearing 311, and then are discharged radially and return to the crank chamber C1.

[0062] As described above, in the present invention, the thrust receiving portion 31 of the variable displacement compressor 1 is provided with the first thrust race 312 and the second thrust race 311C combined in layers, and the oil supply passage 302 is shaped so that the seal space 301 side is narrowed. As a result, the oil flow rate is slow on the inlet 302A side of the oil supply path 302, and the flow rate increases in the narrowed small diameter portion 302C.

[0063] Furthermore, the layered combination of the first thrust race 312 and the second thrust race 311C acts as a Tesla pump as the drive shaft 7 rotates. Therefore, the oil taken into the oil supply passage 302 from the crank chamber C1 increases in flow velocity in the small diameter portion 302C and flows into the seal space 301 between the bushing 21 and the lip seal 17. After that, the oil is drawn into the bushing 21 side by the pumping effect of the rotating first thrust race 312 and second thrust race 311C, and returns to the crank chamber C1 via the thrust receiving portion 31.

[0064] This promotes the supply of oil to the lip seal 17, as well as to the bushing 21, and further promotes the supply of oil to the thrust receiving portion 31, so that these can be lubricated without any hindrance and the generation of sludge can be suppressed.

[0065] In addition, in this embodiment, the small-diameter portion 302C of the oil supply passage 302 is formed in a stepped shape, which makes it possible to more effectively increase the oil flow rate. Furthermore, in this embodiment, the inlet 302A of the oil supply passage 302 is formed in a shape that gradually widens toward the crank chamber C1, which makes it possible to smoothly take in oil from the crank chamber C1 into the oil supply passage 302.

[0066] Furthermore, in this embodiment, the inlet 302A of the oil supply passage 302 is designed to open into the crank chamber C1 vertically above the thrust receiving portion 31, thereby avoiding interference with the thrust receiving portion 31 and allowing oil to flow smoothly from the crank chamber C1 into the oil supply passage 302 by gravity.

[0067] Figure 4 shows a comparison of the weight of oil drawn into the oil supply passage 302. Figure 4(a) shows a case where the first thrust race 312 is not provided in the thrust receiving portion 31, Figure 4(b) shows a case where the first thrust race 312 is provided but the narrow diameter portion 302C is not provided in the oil supply passage 302, and Figure 4(c) shows the variable displacement compressor 1 of the embodiment shown in Figure 3.

[0068] 4(a) and 4(b), it is clear that the first thrust race 312 alone is effective, but as is clear from Fig. 4(c), with the configuration of the variable displacement compressor 1 of the present invention, the amount of oil drawn into the oil supply passage 302 is significantly greater than with the other configurations ((a) and (b)). This significantly improves the lubrication effect of each part.

[0069] In the embodiment, the first thrust race 312 and the second thrust race 311C of the thrust rolling bearing 311 are combined in layers, but more thrust races may be combined in layers.

[0070] Furthermore, although the present invention has been described in the embodiment with reference to a wobble plate compressor, the present invention is not limited to this and can also be applied to a swash plate compressor that does not have a wobble plate.

[0071] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that modifications and changes can be made based on the technical concept of the present invention.

[0072] REFERENCE SIGNS LIST 1 variable displacement compressor 2 cylinder block 2A cylinder bore 3 front housing 4 cylinder head 5 housing 7 drive shaft 8 rotor 9 swash plate 10 wobble plate 12 piston 17 lip seal 21 bushing 31 thrust receiving portion 301 seal space 302 oil supply passage 302A inlet 302C narrow diameter portion 311 thrust rolling bearing 311A ​​rolling element 311C second thrust race 311D third thrust race 312 first thrust race C1 crankcase

Claims

a drive shaft that penetrates the crank chamber and is rotatably supported by the housing via a bushing, with one end protruding from the housing, a rotor that rotates integrally with the drive shaft, a swash plate that rotates with the rotation of the rotor, a conversion mechanism that converts the rotation of the swash plate into reciprocating motion of the pistons, a thrust receiving portion that is provided between the housing and the rotor and receives a thrust force from the pistons, a lip seal that is provided on one end side of the drive shaft relative to the bushing and seals between the drive shaft and the housing, and an oil supply passage that is formed in the housing and has one end communicating with the crank chamber and the other end communicating with a seal space between the bushing and the lip seal, wherein the thrust receiving portion has a plurality of thrust races combined in layers, and the oil supply passage has a shape that is narrowed on the seal space side.

2. The variable displacement compressor according to claim 1, characterized in that the thrust bearing comprises a thrust rolling bearing and a first annular thrust race provided on the housing side of the thrust rolling bearing, the thrust rolling bearing having a plurality of rolling elements and a second and third annular thrust race sandwiching the rolling elements from the housing side and the rotor side, and the first thrust race and the second thrust race are combined in layers.

3. A variable displacement compressor according to claim 1, wherein the oil supply passage has a stepped diameter that narrows toward the sealing space.

4. A variable displacement compressor according to any one of claims 1 to 3, characterized in that the oil supply passage has a shape in which the inlet on the crank chamber side is gradually widened.

5. A variable displacement compressor according to claim 4, wherein the inlet of said oil supply passage opens into said crank chamber vertically above said thrust receiving portion.

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