Scroll Compressor

Abstract

To provide a scroll type compressor which enables a fluid in a first back pressure space to be discharged easily to an intake pressure space.SOLUTION: A fixed scroll 60, a movable scroll 70, and a plate 80 define an intake pressure space K into which a fluid flows from an intake chamber. A back pressure chamber S4 has: a first back pressure space S41 defined by the movable scroll 70 and a shaft support housing 40; and a second back pressure space S42 defined by the plate 80 and a back pressure chamber forming recessed part 48. The shaft support housing 40 has a back pressure supply groove 49 which allows communication between the first back pressure space S41 and the second back pressure space S42. The back pressure supply groove 49 supplies the fluid in the first back pressure space S41 to the second back pressure space S42. A discharge hole 82 penetrates through the plate 80 and allows communication between the second back pressure space S42 and the intake pressure space K. The discharge hole 82 can discharge the fluid in the second back pressure space S42 to the intake pressure space K. The discharge hole 82 overlaps with the back pressure supply groove 49 in an axial direction of a rotary shaft 12.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a scroll compressor. [Background technology]

[0002] The scroll compressor described in Patent Document 1 includes a housing, a rotating shaft, a fixed scroll, a movable scroll, an opposing wall, and an annular plate. The housing has a suction chamber into which a fluid is drawn. The rotating shaft is rotatably supported relative to the housing. The fixed scroll has a fixed base plate, a fixed spiral wall extending from the fixed base plate, and a cylindrical fixed outer peripheral wall extending from the fixed base plate and surrounding the fixed spiral wall. The fixed scroll is fixed to the housing. The movable scroll has a movable base plate facing the fixed base plate and a movable spiral wall extending from the movable base plate toward the fixed base plate and meshing with the fixed spiral wall. The movable scroll is disposed inside the fixed outer peripheral wall. The movable scroll revolves relative to the fixed scroll as the rotating shaft rotates. The opposing wall is disposed opposite the fixed base plate from the movable base plate. The plate is disposed between the movable base plate and the opposing wall. The opposing wall has an annular recessed portion forming a back pressure chamber that is recessed from the surface facing the plate. The opposing wall also has a back pressure supply groove recessed from the opposing surface.

[0003] The scroll compressor has a suction pressure space into which fluid flows from the suction chamber and a back pressure chamber that biases the movable scroll toward the fixed scroll. The suction pressure space is defined by the fixed outer peripheral wall, the movable scroll, and a plate. The back pressure chamber has a first back pressure space defined by the movable scroll and the opposing wall, and a second back pressure space defined by the plate and a back pressure chamber-forming recess. The first and second back pressure spaces are connected by a back pressure supply groove. The back pressure supply groove supplies fluid from the first back pressure space to the second back pressure space.

[0004] In a scroll compressor that compresses a refrigerant fluid, if the temperature inside the housing is lower than the temperature outside the housing for a long period of time, liquid refrigerant accumulates in the back pressure chamber. When the scroll compressor is operated under this condition, the liquid refrigerant accumulated in the back pressure chamber vaporizes, causing an excessive increase in pressure within the back pressure chamber. The increased pressure within the back pressure chamber increases the sliding resistance between the fixed scroll and the movable scroll, and between the movable scroll and the plate. For this reason, it is conceivable to provide a discharge hole in the plate for discharging the fluid within the back pressure chamber to the suction pressure space. The discharge hole penetrates the plate. The discharge hole can communicate between the second back pressure space and the suction pressure space. The discharge hole discharges the fluid within the second back pressure space to the suction pressure space. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-159314 Summary of the Invention [Problem to be solved by the invention]

[0006] In a scroll compressor provided with a discharge hole, fluid in the first back pressure space flows through the back pressure supply groove to the second back pressure space and is then discharged to the suction pressure space through the discharge hole. In other words, the fluid in the first back pressure space must pass through the second back pressure space to be discharged to the suction pressure space. However, the second back pressure space is a narrow space defined by the back pressure chamber-forming recess in the opposing wall and the plate. Therefore, the fluid in the first back pressure space is difficult to discharge to the suction pressure space. [Means for solving the problem]

[0007] A scroll compressor for solving the above problems includes a housing having a suction chamber into which fluid is drawn, a rotary shaft rotatably supported relative to the housing, a fixed scroll having a fixed base plate, a fixed spiral wall erected from the fixed base plate, and a cylindrical fixed outer peripheral wall erected from the fixed base plate and surrounding the fixed spiral wall, the fixed scroll being fixed to the housing, a movable base plate facing the fixed base plate, and a movable spiral wall erected from the movable base plate toward the fixed base plate and engaging with the fixed spiral wall, the movable scroll being disposed inside the fixed outer peripheral wall and revolving relative to the fixed scroll as the rotary shaft rotates, an opposing wall disposed opposite the movable base plate on the opposite side from the fixed base plate, and an annular plate interposed between the movable base plate and the opposing wall, the movable scroll being partitioned by the fixed outer peripheral wall, the movable scroll, and the plate, and the suction chamber is formed in the rotary shaft. a back pressure chamber having a suction pressure space into which the fluid flows from a chamber, a back pressure chamber-forming annular recess recessed from an opposing surface of the opposing wall facing the plate, a first back pressure space defined by the movable scroll and the opposing wall, and a second back pressure space defined by the plate and the back pressure chamber-forming recess, the back pressure chamber biasing the movable scroll toward the fixed scroll, a back pressure supply groove recessed from the opposing surface, connecting the first back pressure space and the second back pressure space, and supplying the fluid in the first back pressure space to the second back pressure space, and a discharge hole penetrating the plate, connecting the second back pressure space and the suction pressure space, and discharging the fluid in the second back pressure space to the suction pressure space, wherein at least a portion of the discharge hole overlaps with the back pressure supply groove in the axial direction of the rotary shaft.

[0008] According to the above configuration, at least a portion of the discharge hole overlaps with the back pressure supply groove in the axial direction of the rotating shaft. Therefore, fluid flowing from the first back pressure space to the back pressure supply groove overlapping with the discharge hole is discharged from the discharge hole to the suction pressure space without flowing through the second back pressure space. This facilitates the discharge of fluid from the first back pressure space to the suction pressure space. As a result, an increase in sliding resistance between the fixed scroll and the movable scroll, and between the movable scroll and the plate, caused by an excessive increase in pressure in the back pressure chamber, can be suppressed.

[0009] In the scroll compressor, the discharge hole may be switched between a discharge state in which it communicates with the suction pressure space and a non-discharge state in which it faces the movable scroll as the movable scroll revolves relative to the fixed scroll.

[0010] For example, when the discharge hole is in a non-discharge state facing the movable scroll, the back pressure chamber is not in communication with the suction pressure space. Therefore, fluid in the back pressure chamber is not discharged into the suction pressure space. On the other hand, when the discharge hole is in a discharge state communicating with the suction pressure space, the back pressure chamber and the suction pressure space are always in communication with each other through the discharge hole. This can result in excessive fluid being discharged into the suction pressure space, which can cause the pressure in the back pressure chamber to drop too low. This risk is particularly pronounced when the discharge hole overlaps the back pressure supply groove. If the pressure in the back pressure chamber drops too low, the biasing force that biases the movable scroll toward the fixed scroll becomes insufficient. In contrast, with the above-described configuration, the discharge hole switches between a discharge state and a non-discharge state as the movable scroll revolves relative to the fixed scroll. Therefore, the fluid in the back pressure chamber can be discharged into the suction pressure space while preventing an excessive drop in pressure in the back pressure chamber.

[0011] In the scroll compressor, the discharge hole may overlap with the back pressure supply groove in the axial direction of the rotary shaft below the rotary shaft in the direction of gravity. When the scroll compressor starts, the fluid in the first back pressure space accumulates below the direction of gravity due to gravity. According to the above configuration, the discharge hole is below the rotating shaft in the direction of gravity and overlaps with the back pressure supply groove in the axial direction of the rotating shaft. Therefore, the fluid accumulated below the direction of gravity in the first back pressure space easily flows into the back pressure supply groove that overlaps with the discharge hole. This makes it easier to discharge the fluid in the first back pressure space to the suction pressure space.

[0012] In the scroll compressor, the opposing wall may be provided with a plurality of back pressure supply grooves, the plurality of back pressure supply grooves being arranged at intervals in the circumferential direction of the plate, and the discharge hole may overlap with some of the plurality of back pressure supply grooves in the axial direction of the rotating shaft.

[0013] For example, if the discharge hole overlaps with all of the back pressure supply grooves in the axial direction of the rotating shaft, the fluid in the back pressure chamber may be excessively discharged into the suction pressure space, which could result in an excessive drop in pressure in the back pressure chamber. In contrast, in the above configuration, the discharge hole overlaps with some of the back pressure supply grooves in the axial direction of the rotating shaft. This makes it easier to prevent the fluid in the back pressure chamber from being excessively discharged into the suction pressure space, resulting in an excessive drop in pressure in the back pressure chamber.

[0014] In the scroll compressor, the back pressure supply groove may be a linear groove extending along a radial direction of the plate. According to the above configuration, the back pressure supply groove is a linear groove extending radially of the plate. Therefore, the path of the fluid from the first back pressure space to the discharge hole is shorter than when, for example, the back pressure supply groove has a portion extending radially of the plate and a portion extending circumferentially of the plate. Therefore, the fluid in the first back pressure space can be more easily discharged to the suction pressure space.

[0015] In the scroll compressor, the back pressure chamber may have a third back pressure space defined by the movable scroll and the plate and communicating with the first back pressure space.

[0016] The central portion of the movable base plate of the movable scroll is urged toward the fixed scroll by the pressure of the fluid in the first back pressure space. According to the above configuration, the back pressure chamber has a third back pressure space defined by the movable scroll and the plate, in addition to the first and second back pressure spaces. This causes the outer peripheral portion of the movable base plate to be urged toward the fixed scroll by the pressure of the fluid in the third back pressure space. In other words, not only the central portion but also the outer peripheral portion of the movable base plate is urged toward the fixed scroll. Therefore, the movable scroll can be stably urged toward the fixed scroll. Furthermore, because the third back pressure space is connected to the first back pressure space, the volume of the first back pressure space is substantially increased. However, even in this case, the overlapping of the discharge hole and the back pressure supply groove facilitates the discharge of fluid from the first and third back pressure spaces to the suction pressure space. [Effects of the Invention]

[0017] According to the present invention, the fluid in the first back pressure space can be easily discharged to the suction pressure space. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing a scroll compressor. [Figure 2] 1A is a front view showing the support housing, the plate, and the rotary shaft, and FIG. 1B is an enlarged view showing a part of FIG. 1A. [Figure 3] FIG. 2 is a partial cross-sectional view showing the scroll compressor when the discharge hole is in a discharge state. [Figure 4] FIG. 2 is a partial cross-sectional view showing the scroll compressor when the discharge hole is in a non-discharge state. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, one embodiment of a scroll compressor will be described with reference to Figs. 1 to 4. The scroll compressor of this embodiment is mounted on a vehicle. The scroll compressor of this embodiment is used in a vehicle air conditioner. The scroll compressor of this embodiment compresses a refrigerant as a fluid.

[0020] As shown in FIG. 1, a scroll compressor 10 includes a housing 11, a rotary shaft 12, an electric motor 13, and a compression section 14. <Housing> The housing 11 accommodates the rotary shaft 12, the electric motor 13, and the compression unit 14. The housing 11 is made of metal. In this embodiment, the housing 11 is made of aluminum. The housing 11 includes a motor housing 20, a discharge housing 30, and a support housing 40.

[0021] The motor housing 20 is cylindrical and has a bottom. The motor housing 20 has a plate-shaped bottom wall 21 and a peripheral wall 22 that extends cylindrically from the outer periphery of the bottom wall 21. The motor housing 20 has a cylindrical boss 23 that protrudes from the inner surface of the bottom wall 21.

[0022] The motor housing 20 has a plurality of first communication passage-forming recesses 24. One first communication passage-forming recess 24 is shown in FIG. 1. The plurality of first communication passage-forming recesses 24 are arranged at intervals in the circumferential direction of the peripheral wall 22 of the motor housing 20. The first communication passage-forming recesses 24 are recessed from the inner peripheral surface of the peripheral wall 22 of the motor housing 20. The first communication passage-forming recesses 24 are provided on the opening side of the peripheral wall 22 of the motor housing 20. The first communication passage-forming recesses 24 open at the tip end surface 22a of the peripheral wall 22 of the motor housing 20.

[0023] The motor housing 20 has a plurality of female threaded holes 25. One female threaded hole 25 is shown in FIG. 1 . The plurality of female threaded holes 25 are arranged at intervals in the circumferential direction of the peripheral wall 22 of the motor housing 20. The female threaded holes 25 are provided at positions in the circumferential direction of the peripheral wall 22 of the motor housing 20 that are different from the first communication passage forming recess 24. The female threaded hole 25 is formed in the tip end surface 22 a of the peripheral wall 22 of the motor housing 20.

[0024] The discharge housing 30 has a cylindrical shape with a bottom. The discharge housing 30 has a plate-shaped bottom wall 31 and a peripheral wall 32 that extends cylindrically from the outer periphery of the bottom wall 31. The discharge housing 30 has a first discharge chamber forming recess 33. The first discharge chamber forming recess 33 is recessed from the inner surface of the bottom wall 31 of the discharge housing 30.

[0025] The discharge housing 30 has a plurality of second communication passage forming recesses 34. One second communication passage forming recess 34 is shown in FIG. 1. The plurality of second communication passage forming recesses 34 are arranged at intervals in the circumferential direction of the peripheral wall 32 of the discharge housing 30. The second communication passage forming recess 34 is recessed from the inner peripheral surface of the peripheral wall 32 of the discharge housing 30. The second communication passage forming recess 34 is provided on the opening side of the peripheral wall 32 of the discharge housing 30. The second communication passage forming recess 34 opens at the tip end surface 32a of the peripheral wall 32 of the discharge housing 30.

[0026] The discharge housing 30 has a plurality of first bolt insertion holes 35. One first bolt insertion hole 35 is shown in FIG. 1 . The plurality of first bolt insertion holes 35 are arranged at intervals in the circumferential direction of the peripheral wall 32 of the discharge housing 30. The first bolt insertion holes 35 are provided at positions in the circumferential direction of the peripheral wall 32 of the discharge housing 30 that are different from the second communication passage forming recess 34. The first bolt insertion holes 35 penetrate the peripheral wall 32 of the discharge housing 30.

[0027] An intake port (not shown) is formed in the motor housing 20. An exhaust port (not shown) is formed in the exhaust housing 30. One end of an external refrigerant circuit (not shown) is connected to the intake port, and the other end of the external refrigerant circuit is connected to the exhaust port.

[0028] The journal housing 40 is cylindrical and has a bottom. The journal housing 40 has a plate-shaped bottom wall 41 and a peripheral wall 42 that extends cylindrically from the outer periphery of the bottom wall 41. The journal housing 40 has an annular flange wall 43. The flange wall 43 extends radially outward from the tip of the peripheral wall 42 of the journal housing 40.

[0029] The inner peripheral surface of the peripheral wall 42 of the journal housing 40 has a large-diameter inner peripheral surface 42a, a medium-diameter inner peripheral surface 42b that is smaller in diameter than the large-diameter inner peripheral surface 42a, and a small-diameter inner peripheral surface 42c that is smaller in diameter than the medium-diameter inner peripheral surface 42b. The large-diameter inner peripheral surface 42a, the medium-diameter inner peripheral surface 42b, and the small-diameter inner peripheral surface 42c are aligned in this order from the opening side of the journal housing 40 toward the bottom wall 41.

[0030] The journal housing 40 has a journal insertion hole 44. The journal insertion hole 44 penetrates the bottom wall 41 of the journal housing 40. As shown in FIG. 2(a), the journal housing 40 has a plurality of communication passage forming holes 45. The plurality of communication passage forming holes 45 are arranged at intervals in the circumferential direction of the flange wall 43. The communication passage forming holes 45 penetrate the outer periphery of the flange wall 43. The journal housing 40 also has a plurality of second bolt insertion holes 46. The plurality of second bolt insertion holes 46 are arranged at intervals in the circumferential direction of the flange wall 43. The second bolt insertion holes 46 are provided at positions different from the communication passage forming holes 45 in the circumferential direction of the flange wall 43. The second bolt insertion holes 46 penetrate the outer periphery of the flange wall 43.

[0031] 1, the motor housing 20 and the discharge housing 30 are arranged so that the leading end surface 22a of the peripheral wall 22 of the motor housing 20 and the leading end surface 32a of the peripheral wall 32 of the discharge housing 30 face each other. The axial direction of the peripheral wall 22 of the motor housing 20 and the axial direction of the peripheral wall 32 of the discharge housing 30 coincide with each other.

[0032] The support housing 40 is disposed between the motor housing 20 and the discharge housing 30. The axial direction of the peripheral wall 42 of the support housing 40 coincides with the axial direction of the peripheral wall 22 of the motor housing 20 and the axial direction of the peripheral wall 32 of the discharge housing 30. The peripheral wall 42 of the support housing 40 extends from the bottom wall 41 toward the discharge housing 30. The flange wall 43 is located between the peripheral wall 22 of the motor housing 20 and the peripheral wall 32 of the discharge housing 30. The support housing 40 has an end face 40a that faces the tip face 32a of the peripheral wall 32 of the discharge housing 30.

[0033] The first communication passage-forming recess 24 of the motor housing 20, the communication passage-forming hole 45 of the journal housing 40, and the second communication passage-forming recess 34 of the discharge housing 30 are aligned in the axial direction of the peripheral walls 22, 32, 42. The first communication passage-forming recess 24, the communication passage-forming hole 45, and the second communication passage-forming recess 34 form a communication passage R.

[0034] The female threaded hole 25 of the motor housing 20, the second bolt insertion hole 46 of the journal housing 40, and the first bolt insertion hole 35 of the discharge housing 30 are aligned in the axial direction of the peripheral walls 22, 32, 42. The motor housing 20, journal housing 40, and discharge housing 30 are connected to one another by threading a bolt B inserted through the first bolt insertion hole 35 and the second bolt insertion hole 46 into the female threaded hole 25. The flange wall 43 is sandwiched between the peripheral wall 22 of the motor housing 20 and the peripheral wall 32 of the discharge housing 30.

[0035] The housing 11 has a motor chamber S1. The motor chamber S1 is defined by the bottom wall 21 and peripheral wall 22 of the motor housing 20 and the support housing 40. Refrigerant is drawn into the motor chamber S1 from an external refrigerant circuit through a suction port. Therefore, the motor chamber S1 is a suction chamber into which the refrigerant is drawn.

[0036] As shown in FIGS. 1 and 2(a), the journal housing 40 has a plurality of pins 47. The journal housing 40 of this embodiment has six pins 47. The pins 47 are arranged at equal intervals in the circumferential direction of the flange wall 43. The journal housing 40 has an annular back pressure chamber-forming recess 48. The back pressure chamber-forming recess 48 is recessed from the end face 40a of the journal housing 40. Each pin 47 protrudes from the bottom surface of the back pressure chamber-forming recess 48.

[0037] As shown in FIGS. 2(a) and 3, the journal housing 40 has a back pressure supply groove 49. The journal housing 40 of this embodiment has six back pressure supply grooves 49 as the multiple back pressure supply grooves 49. The multiple back pressure supply grooves 49 are arranged at equal intervals in the circumferential direction of the flange wall 43. The back pressure supply grooves 49 are provided at positions different from the pins 47 in the circumferential direction of the flange wall 43. The back pressure supply grooves 49 and the pins 47 are arranged alternately in the circumferential direction of the flange wall 43.

[0038] 3, each back pressure supply groove 49 is recessed from the end face 40a of the journal housing 40. In this embodiment, the depth from the end face 40a of the journal housing 40 to the bottom surface of the back pressure supply groove 49 is greater than the depth from the end face 40a of the journal housing 40 to the bottom surface of the back pressure chamber-forming recess 48. In this embodiment, each back pressure supply groove 49 is a groove that extends linearly in the radial direction of the flange wall 43.

[0039] Each back pressure supply groove 49 opens at the large diameter inner circumferential surface 42a of the peripheral wall 42 of the journal housing 40. Each back pressure supply groove 49 extends from the large diameter inner circumferential surface 42a of the peripheral wall 42 of the journal housing 40 to a position where it overlaps with the back pressure chamber forming recess 48. Each back pressure supply groove 49 communicates with the back pressure chamber forming recess 48.

[0040] <Rotation axis> 1, the rotating shaft 12 is accommodated in a motor chamber S1. The axial direction of the rotating shaft 12 coincides with the axial direction of a peripheral wall 22 of a motor housing 20. The scroll compressor 10 of this embodiment is mounted on a vehicle in an orientation in which the axial direction of the rotating shaft 12 is perpendicular to the direction of gravity Z.

[0041] A first axial end of the rotating shaft 12 is inserted into the boss 23 of the motor housing 20. A first bearing 15 is disposed between the outer peripheral surface of the rotating shaft 12 and the inner peripheral surface of the boss 23. The first bearing 15 is a rolling bearing. The first end of the rotating shaft 12 is rotatably supported by the motor housing 20 via the first bearing 15.

[0042] The rotating shaft 12 is inserted through a shaft insertion hole 44 of the support housing 40. A second end of the rotating shaft 12, which is the end opposite to the first end, protrudes into the support housing 40. A second bearing 16 is housed between the outer circumferential surface of the rotating shaft 12 and the medium-diameter inner circumferential surface 42b of the support housing 40. The second bearing 16 is a rolling bearing. The second end of the rotating shaft 12 is rotatably supported relative to the support housing 40 via the second bearing 16.

[0043] 2(a), in this embodiment, of the six back pressure supply grooves 49 provided in the support housing 40, three back pressure supply grooves 49 are located below the rotating shaft 12 in the direction of gravity Z. The remaining three back pressure supply grooves 49 are located above the rotating shaft 12 in the direction of gravity Z.

[0044] 1, a seal member 17 is disposed between the outer peripheral surface of the rotating shaft 12 and the small-diameter inner peripheral surface 42c of the journal housing 40. The seal member 17 seals between the outer peripheral surface of the rotating shaft 12 and the small-diameter inner peripheral surface 42c of the journal housing 40. The seal member 17 prevents refrigerant in a first back pressure space S41 (described later) from leaking into the motor chamber S1.

[0045] An eccentric shaft 18 is integrally formed on the shaft end surface 12a on the second end side of the rotating shaft 12. The eccentric shaft 18 rotates integrally with the rotating shaft 12. The axial direction of the eccentric shaft 18 coincides with the axial direction of the rotating shaft 12. An axis L18 of the eccentric shaft 18 is provided at a position eccentric to the axis L12 of the rotating shaft 12.

[0046] A bushing 52 with an integrated balance weight 51 is fitted onto the outer peripheral surface of the eccentric shaft 18. The balance weight 51 is formed integrally with the bushing 52. The balance weight 51 is accommodated inside the large-diameter inner peripheral surface 42a of the journal housing 40.

[0047] <Electric motor> The electric motor 13 rotates the rotary shaft 12. The electric motor 13 is housed in the motor chamber S1. The electric motor 13 has a rotor 13a and a cylindrical stator 13b.

[0048] The rotor 13a has a cylindrical rotor core 130 and a permanent magnet (not shown). The rotating shaft 12 is inserted through the rotor core 130. The rotating shaft 12 is fixed to the rotor core 130. The permanent magnet is embedded in the rotor core 130. The stator 13b is disposed on the outside of the rotor 13a. The stator 13b has a cylindrical stator core 131 and a coil 132. The outer peripheral surface of the stator core 131 is fixed to the inner peripheral surface of the peripheral wall 22 of the motor housing 20. The coil 132 is wound around the stator core 131. When a rotating magnetic field is generated in the stator 13b by energizing the coil 132, the rotor 13a rotates. The rotating shaft 12 rotates integrally with the rotor 13a.

[0049] <Compression section> The compression section 14 compresses the refrigerant as the rotary shaft 12 rotates. The electric motor 13 rotates the rotary shaft 12 to drive the compression section 14. The compression section 14 is housed in a space defined by the bottom wall 31 and peripheral wall 32 of the discharge housing 30 and the support housing 40.

[0050] The compression section 14 has a fixed scroll 60 and a movable scroll 70. The fixed scroll 60 is located closer to the bottom wall 31 of the discharge housing 30 than the movable scroll 70 in the axial direction of the rotating shaft 12. The movable scroll 70 is located closer to the journal housing 40 than the fixed scroll 60 in the axial direction of the rotating shaft 12.

[0051] The fixed scroll 60 has a disk-shaped fixed base plate 61, a spiral-shaped fixed spiral wall 62, and a cylindrical fixed outer peripheral wall 63. The fixed base plate 61 has a first surface 61a and a second surface 61b. The first surface 61a and the second surface 61b are surfaces perpendicular to the plate thickness direction of the fixed base plate 61. The first surface 61a of the fixed base plate 61 faces the inner surface of the bottom wall 31 of the discharge housing 30. The second surface 61b of the fixed base plate 61 is the surface of the fixed base plate 61 opposite the first surface 61a. The fixed spiral wall 62 and the fixed outer peripheral wall 63 each stand upright from the second surface 61b of the fixed base plate 61. The fixed outer peripheral wall 63 surrounds the fixed spiral wall 62. The fixed scroll 60 is fixed to the housing 11 by being sandwiched between the bottom wall 31 of the discharge housing 30 and the support housing 40.

[0052] The fixed scroll 60 has a second discharge chamber-forming recess 64. The second discharge chamber-forming recess 64 is recessed from the first surface 61a of the fixed base plate 61. The second discharge chamber-forming recess 64, together with the first discharge chamber-forming recess 33 of the discharge housing 30, defines the discharge chamber S2.

[0053] The fixed scroll 60 has a discharge port 65. The discharge port 65 is a through-hole that penetrates the center of the fixed base plate 61. The discharge port 65 opens at the bottom surface of the second discharge chamber-forming recess 64. A valve mechanism 66 that opens and closes the discharge port 65 is attached to the bottom surface of the second discharge chamber-forming recess 64.

[0054] The fixed scroll 60 has an introduction hole 67. The introduction hole 67 penetrates the fixed outer peripheral wall 63 in the thickness direction. The movable scroll 70 has a disk-shaped movable base plate 71 and a spiral-shaped movable spiral wall 72. The movable scroll 70 is disposed inside the fixed outer peripheral wall 63.

[0055] The movable substrate 71 has a first surface 71a and a second surface 71b. The first surface 71a and the second surface 71b are surfaces perpendicular to the thickness direction of the movable substrate 71. The first surface 71a of the movable substrate 71 faces the second surface 61b of the fixed substrate 61. The tip surface of the fixed spiral wall 62 contacts the first surface 71a of the movable substrate 71. The second surface 71b of the movable substrate 71 is the surface of the movable substrate 71 opposite to the first surface 71a. The movable spiral wall 72 stands upright from the first surface 71a of the movable substrate 71. The movable spiral wall 72 stands upright from the movable substrate 71 toward the fixed substrate 61. The movable spiral wall 72 is engaged with the fixed spiral wall 62. The tip surface of the movable spiral wall 72 contacts the second surface 61b of the fixed substrate 61.

[0056] The pivot support housing 40 is an opposing wall disposed opposite the fixed substrate 61 with respect to the movable substrate 71. Therefore, the opposing wall is a part of the housing 11. The fixed base plate 61, the fixed spiral wall 62, the movable base plate 71, and the movable spiral wall 72 define a compression chamber S3 that compresses the refrigerant. The compression chamber S3 is in communication with the communication passage R through an inlet hole 67. The refrigerant in the motor chamber S1 is introduced into the compression chamber S3 from the communication passage R through the inlet hole 67. The refrigerant compressed in the compression chamber S3 is discharged into the discharge chamber S2 through a discharge port 65.

[0057] The movable scroll 70 has an accommodating recess 73. The accommodating recess 73 is recessed from the second surface 71b of the movable base plate 71. The accommodating recess 73 is located in the center of the movable base plate 71. The eccentric shaft 18 and the bushing 52 are accommodated in the accommodating recess 73. A third bearing 19 is disposed between the outer peripheral surface of the bushing 52 and the inner peripheral surface of the accommodating recess 73. The third bearing 19 is a rolling bearing. The movable scroll 70 is supported by the eccentric shaft 18 via the third bearing 19 and the bushing 52 so as to be rotatable relative to the eccentric shaft 18.

[0058] The movable scroll 70 has a plurality of rotation restricting recesses 74. The plurality of rotation restricting recesses 74 are arranged at intervals in the circumferential direction of the movable base plate 71. The plurality of rotation restricting recesses 74 are provided around the accommodating recess 73. Each rotation restricting recess 74 is recessed from the second surface 71b of the movable base plate 71. Each rotation restricting recess 74 is circular. An annular ring member 75 is fitted onto the inner circumferential surface of each rotation restricting recess 74. A pin 47 is inserted inside each ring member 75.

[0059] The movable scroll 70 revolves relative to the fixed scroll 60 as the rotating shaft 12 rotates. More specifically, the rotation of the rotating shaft 12 is transmitted to the movable scroll 70 via the eccentric shaft 18, the bushing 52, and the third bearing 19. As a result, the movable scroll 70 attempts to rotate on its axis, but contact between the pins 47 and the inner circumferential surfaces of the ring members 75 prevents the movable scroll 70 from rotating on its axis. The movable scroll 70 is only allowed to revolve relative to the fixed scroll 60. The movable scroll 70 revolves around the rotation axis L12 of the rotating shaft 12 while its rotation is prevented, with the movable spiral wall 72 in contact with the fixed spiral wall 62. As the movable scroll 70 revolves relative to the fixed scroll 60, the volume of the compression chamber S3 decreases, and the refrigerant drawn into the compression chamber S3 is compressed. The balance weight 51 reduces the amount of imbalance of the movable scroll 70 by offsetting the centrifugal force acting on the movable scroll 70 when the movable scroll 70 revolves.

[0060] The movable scroll 70 has an annular protruding portion 76. The protruding portion 76 protrudes from the second surface 71b of the movable base plate 71. The protruding portion 76 surrounds the plurality of rotation restricting recesses 74.

[0061] The movable scroll 70 has a back pressure introduction passage 77. The back pressure introduction passage 77 penetrates both the movable base plate 71 and the movable spiral wall 72. One end of the back pressure introduction passage 77 opens at the tip end surface of the movable spiral wall 72, and the other end of the back pressure introduction passage 77 opens at the bottom surface of the installation recess 73.

[0062] <Plate> An annular plate 80 is interposed between the journal support housing 40 and the movable scroll 70. The thickness direction of the plate 80 coincides with the axial direction of the peripheral wall 42 of the journal support housing 40 and the direction in which the movable spiral wall 72 stands upright from the movable base plate 71.

[0063] The plate 80 has a first surface 80a and a second surface 80b. The first surface 80a and the second surface 80b are each perpendicular to the thickness direction of the plate 80. The first surface 80a of the plate 80 faces the end surface 40a of the journal housing 40. Therefore, the end surface 40a of the journal housing 40 is the opposing surface of the opposing wall that faces the plate 80. The second surface 80b of the plate 80 is the surface opposite to the first surface 80a of the plate 80. The second surface 80b of the plate 80 faces the compression section 14.

[0064] A portion of the end face 40a of the support housing 40 located inside the back pressure chamber forming recess 48 abuts against the first surface 80a of the plate 80. Furthermore, a portion of the end face 40a of the support housing 40 located outside the back pressure chamber forming recess 48 abuts against the first surface 80a of the plate 80. The protrusion 76 of the movable scroll 70 abuts against the second surface 80b of the plate 80.

[0065] The inner diameter of the plate 80 is approximately the same as the diameter of the large-diameter inner circumferential surface 42a of the journal housing 40. The inner peripheral edge of the plate 80 is aligned with the large-diameter inner circumferential surface 42a in the axial direction of the rotating shaft 12. The back pressure chamber forming recess 48 of the journal housing 40 extends in the circumferential direction of the plate 80. The back pressure supply groove 49 of the journal housing 40 extends along the radial direction of the plate 80.

[0066] The fixed outer peripheral wall 63 of the fixed scroll 60, the movable scroll 70, and the plate 80 define a suction pressure space K. The suction pressure space K is in communication with the introduction hole 67. The refrigerant in the motor chamber S1 also flows from the communication passage R through the introduction hole 67 into the suction pressure space K.

[0067] As shown in FIG. 2(a), the plate 80 has a plurality of pin insertion holes 81. The plurality of pin insertion holes 81 are arranged at intervals in the circumferential direction of the plate 80. Each pin insertion hole 81 penetrates the plate 80 in the thickness direction. The pins 47 are inserted into the pin insertion holes 81. The plate 80 also has discharge holes 82. The discharge holes 82 penetrate the plate 80 in the thickness direction.

[0068] 2(b) and 3, the discharge hole 82 overlaps with the back pressure supply groove 49 in the axial direction of the rotating shaft 12. In this embodiment, the discharge hole 82 overlaps with some of the multiple back pressure supply grooves 49. More specifically, the discharge hole 82 overlaps with the back pressure supply groove 49a, which is the lowest of the six back pressure supply grooves 49 in the direction of gravity Z. Therefore, the discharge hole 82 overlaps with the back pressure supply groove 49 below the rotating shaft 12 in the direction of gravity Z. In addition, in this embodiment, the entire discharge hole 82 overlaps with the back pressure supply groove 49.

[0069] <Back pressure chamber> A back pressure chamber S4 is formed within the housing 11. The back pressure chamber S4 has a first back pressure space S41, a second back pressure space S42, and a third back pressure space S43.

[0070] The first back pressure space S41 is defined by the support housing 40 and the movable scroll 70. More specifically, the first back pressure space S41 is defined by the inner circumferential surface of the peripheral wall 42 of the support housing 40 and the inner surface of the accommodation recess 73 of the movable scroll 70. The first back pressure space S41 is in communication with the compression chamber S3 via a back pressure introducing passage 77. The back pressure introducing passage 77 introduces the refrigerant in the compression chamber S3 into the first back pressure space S41.

[0071] The second back pressure space S42 is defined by the support housing 40 and the plate 80. More specifically, the second back pressure space S42 is defined by the inner surface of the back pressure chamber forming recess 48 of the support housing 40 and the first surface 80a of the plate 80. The second back pressure space S42 is in communication with the first back pressure space S41 by a back pressure supply groove 49. The back pressure supply groove 49 supplies the refrigerant in the first back pressure space S41 to the second back pressure space S42.

[0072] The abutment between a portion of the end face 40a of the support housing 40 located inside the back pressure chamber forming recess 48 and the first surface 80a of the plate 80 prevents the refrigerant in the first back pressure space S41 from leaking into the second back pressure space S42. The abutment between a portion of the end face 40a of the support housing 40 located outside the back pressure chamber forming recess 48 and the first surface 80a of the plate 80 also prevents the refrigerant in the second back pressure space S42 from leaking into the communicating passage R.

[0073] 3 and 4, the position of the movable scroll 70 relative to the plate 80 changes as the movable scroll 70 revolves relative to the fixed scroll 60. The discharge hole 82 of the plate 80 can be in a discharge state in which it communicates with the suction pressure space K as shown in Fig. 3, or in a non-discharge state in which it faces the movable scroll 70 as shown in Fig. 4. The discharge hole 82 switches between the discharge state and the non-discharge state as the movable scroll 70 revolves relative to the fixed scroll 60.

[0074] As shown in FIG. 3, when the discharge hole 82 is in the discharge state, the second back pressure space S42 and the suction pressure space K are in communication with each other through the discharge hole 82. Therefore, the refrigerant in the second back pressure space S42 is discharged from the discharge hole 82 to the suction pressure space K. On the other hand, as shown in FIG. 4, when the discharge hole 82 is in the non-discharge state, the second back pressure space S42 and the suction pressure space K are not in communication with each other. Therefore, the refrigerant in the second back pressure space S42 is not discharged to the suction pressure space K. In this way, the discharge hole 82 can communicate the second back pressure space S42 with the suction pressure space K. The discharge hole 82 can discharge the refrigerant in the second back pressure space S42 to the suction pressure space K.

[0075] The third back pressure space S43 is defined by the movable scroll 70 and the plate 80. More specifically, the third back pressure space S43 is defined by the inner surface of the rotation restricting recess 74 of the movable scroll 70 and the second surface 80b of the plate 80. The third back pressure space S43 is a space that is formed when the opening of the rotation restricting recess 74 of the movable scroll 70 is covered by the plate 80 due to the orbital motion of the movable scroll 70 relative to the fixed scroll 60.

[0076] The third back pressure space S43 is in communication with the first back pressure space S41. The third back pressure space S43 is aligned with the second back pressure space S42 in the axial direction of the rotary shaft 12 via the plate 80. The third back pressure space S43 is located inside the suction pressure space K. The protruding portion 76 of the movable scroll 70 abuts against the plate 80, thereby preventing the refrigerant in the rotation restricting recess 74 from leaking into the suction pressure space K.

[0077] The refrigerant compressed in the compression chamber S3 is introduced into the first back pressure space S41 of the back pressure chamber S4 through the back pressure introduction passage 77. The central portion of the movable base plate 71 of the movable scroll 70 is urged toward the fixed scroll 60 by the pressure of the refrigerant introduced into the first back pressure space S41.

[0078] A portion of the refrigerant introduced into the first back pressure space S41 flows into the rotation restricting recess 74 and is introduced into the third back pressure space S43. The portion of the outer circumferential side of the movable base plate 71 of the movable scroll 70 is urged toward the fixed scroll 60 by the pressure of the refrigerant in the third back pressure space S43. In addition, the plate 80 is pressed toward the support housing 40 by the pressure of the refrigerant in the third back pressure space S43.

[0079] A portion of the refrigerant introduced into the first back pressure space S41 is supplied to the second back pressure space S42 through each back pressure supply groove 49. The plate 80 is pressed toward the movable scroll 70 by the pressure of the refrigerant in the second back pressure space S42. The direction in which the refrigerant supplied to the second back pressure space S42 presses the plate 80 is opposite the direction in which the refrigerant introduced into the third back pressure space S43 presses the plate 80. This prevents the plate 80 from deforming in the plate thickness direction. The movable scroll 70 is also urged toward the fixed scroll 60 via the plate 80 by the pressure of the refrigerant in the second back pressure space S42.

[0080] In this way, the back pressure chamber S4 urges the movable scroll 70 toward the fixed scroll 60 by introducing the refrigerant compressed in the compression chamber S3. When the movable scroll 70 is urged toward the fixed scroll 60, the tip end face of the movable spiral wall 72 is pressed against the second surface 61b of the fixed base plate 61, thereby ensuring the airtightness of the compression chamber S3.

[0081] [Operation of this embodiment] The operation of this embodiment will be described. The plate 80 has a discharge hole 82. The discharge hole 82 penetrates the plate 80. The discharge hole 82 can communicate between the second back pressure space S42 and the suction pressure space K. The discharge hole 82 overlaps in the axial direction of the rotating shaft 12 with the back pressure supply groove 49a, which is located lowest in the gravity direction Z among the multiple back pressure supply grooves 49. The refrigerant that flows from the first back pressure space S41 to the back pressure supply groove 49 that does not overlap with the discharge hole 82 is supplied to the second back pressure space S42. The refrigerant supplied to the second back pressure space S42 flows in the circumferential direction of the plate 80 along the back pressure chamber-forming recess 48 and is then discharged from the discharge hole 82 to the suction pressure space K. The refrigerant that flows from the first back pressure space S41 to the back pressure supply groove 49a that overlaps with the discharge hole 82 is discharged from the discharge hole 82 to the suction pressure space K without flowing through the second back pressure space S42. Therefore, the refrigerant in the first back pressure space S41 is easily discharged to the suction pressure space K.

[0082] [Effects of this embodiment] The effects of this embodiment will be described. (1) The plate 80 has a discharge hole 82. The discharge hole 82 penetrates the plate 80. The discharge hole 82 can connect the second back pressure space S42 and the suction pressure space K. The discharge hole 82 can discharge the refrigerant in the second back pressure space S42 to the suction pressure space K. The discharge hole 82 overlaps, in the axial direction of the rotating shaft 12, with the back pressure supply groove 49, which connects the first back pressure space S41 and the second back pressure space S42. Therefore, the refrigerant that flows from the first back pressure space S41 to the back pressure supply groove 49 that overlaps with the discharge hole 82 is discharged from the discharge hole 82 to the suction pressure space K without flowing through the second back pressure space S42. This makes it easy to discharge the refrigerant in the first back pressure space S41 to the suction pressure space K. As a result, an increase in the sliding resistance between the fixed scroll 60 and the movable scroll 70 and between the movable scroll 70 and the plate 80 due to an excessive increase in pressure in the back pressure chamber S4 can be suppressed.

[0083] (2) For example, when the discharge hole 82 is in a non-discharge state in which it faces the movable scroll 70, the back pressure chamber S4 and the suction pressure space K are not in communication. Therefore, the refrigerant in the back pressure chamber S4 is not discharged into the suction pressure space K. On the other hand, when the discharge hole 82 is in a discharge state in which it is in communication with the suction pressure space K, the back pressure chamber S4 and the suction pressure space K are always in communication with each other through the discharge hole 82. Therefore, the refrigerant in the back pressure chamber S4 may be excessively discharged into the suction pressure space K, which could cause the pressure in the back pressure chamber S4 to drop too low. If the pressure in the back pressure chamber S4 drops too low, the biasing force that biases the movable scroll 70 against the fixed scroll 60 becomes insufficient. In contrast, in this embodiment, the discharge hole 82 switches between a discharge state and a non-discharge state as the movable scroll 70 revolves relative to the fixed scroll 60. Therefore, the refrigerant in the back pressure chamber S4 can be discharged into the suction pressure space K while preventing the pressure in the back pressure chamber S4 from dropping too low.

[0084] (3) When the scroll compressor 10 is started, the refrigerant in the first back pressure space S41 accumulates below in the direction of gravity Z due to gravity. In this embodiment, the discharge hole 82 is below the rotating shaft 12 in the direction of gravity Z and overlaps with the back pressure supply groove 49 in the axial direction of the rotating shaft 12. Therefore, the refrigerant that accumulates below in the direction of gravity Z in the first back pressure space S41 easily flows into the back pressure supply groove 49 that overlaps with the discharge hole 82. Therefore, the refrigerant in the first back pressure space S41 is easily discharged to the suction pressure space K.

[0085] (4) The support housing 40 is provided with a plurality of back pressure supply grooves 49. The plurality of back pressure supply grooves 49 are arranged at intervals in the circumferential direction of the plate 80. For example, if the discharge hole 82 overlaps with all of the back pressure supply grooves 49 in the axial direction of the rotating shaft 12, the refrigerant in the back pressure chamber S4 may be excessively discharged into the suction pressure space K, which may cause the pressure in the back pressure chamber S4 to drop too low. In contrast, in the present embodiment, the discharge hole 82 overlaps with one of the plurality of back pressure supply grooves 49 in the axial direction of the rotating shaft 12. This makes it easy to prevent the pressure in the back pressure chamber S4 from dropping too low, which may occur when the refrigerant in the back pressure chamber S4 is excessively discharged into the suction pressure space K.

[0086] (5) The back pressure supply groove 49 of the present embodiment is a linear groove extending radially of the plate 80. Therefore, the refrigerant path from the first back pressure space S41 to the discharge hole 82 is shorter than when the back pressure supply groove 49 has a portion extending radially of the plate 80 and a portion extending circumferentially of the plate 80. Therefore, the refrigerant in the first back pressure space S41 can be more easily discharged to the suction pressure space K.

[0087] (6) In addition to the first back pressure space S41 and the second back pressure space S42, the back pressure chamber S4 has a third back pressure space S43 that is defined by the movable scroll 70 and the plate 80 and communicates with the first back pressure space S41. Therefore, the outer peripheral portion of the movable base plate 71 of the movable scroll 70 is urged toward the fixed scroll 60 by the pressure of the refrigerant in the third back pressure space S43. In other words, not only is the central portion of the movable base plate 71 urged toward the fixed scroll 60 by the pressure of the refrigerant in the first back pressure space S41, but the outer peripheral portion is also urged toward the fixed scroll 60. Therefore, the movable scroll 70 can be stably urged toward the fixed scroll 60. Furthermore, because the third back pressure space S43 communicates with the first back pressure space S41, the volume of the first back pressure space S41 is substantially increased. Even in this case, the discharge hole 82 and the back pressure supply groove 49 overlap with each other, so that the refrigerant in the first back pressure space S41 and the third back pressure space S43 can be easily discharged to the suction pressure space K.

[0088] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0089] In the above embodiment, the entire discharge hole 82 overlaps with the back pressure supply groove 49 in the axial direction of the rotating shaft 12. However, the discharge hole 82 may partially overlap with the back pressure supply groove 49 in the axial direction of the rotating shaft 12. In other words, it is sufficient that at least a portion of the discharge hole 82 overlaps with the back pressure supply groove 49 in the axial direction of the rotating shaft 12.

[0090] The size of the discharge hole 82 may be changed as needed. The size of the discharge hole 82 is set based on the balance between the amount of refrigerant discharged from the back pressure chamber S4 to the suction pressure space K and the pressure within the back pressure chamber S4. The larger the discharge hole 82, the greater the amount of refrigerant discharged from the back pressure chamber S4 to the suction pressure space K.

[0091] The position of the discharge hole 82 may be changed as appropriate as long as the discharge hole 82 overlaps with the back pressure supply groove 49 in the axial direction of the rotating shaft 12. Changing the position of the discharge hole 82 changes the ratio of the time the discharge hole 82 is in the discharge state to the time it is in the non-discharge state. The longer the time the discharge hole 82 is in the discharge state, the greater the amount of refrigerant discharged from the back pressure chamber S4 to the suction pressure space K. The position of the discharge hole 82 is set based on the balance between the amount of refrigerant discharged from the back pressure chamber S4 to the suction pressure space K and the pressure within the back pressure chamber S4.

[0092] In the above embodiment, the support housing 40 has a plurality of back pressure supply grooves 49 . However, the support housing 40 may have a single back pressure supply groove 49 . The plate 80 may have a plurality of discharge holes 82 that overlap with the back pressure supply groove 49 in the axial direction of the rotary shaft 12. In other words, the discharge holes 82 and the back pressure supply groove 49 may overlap at a plurality of locations.

[0093] The discharge hole 82 may overlap with the back pressure supply grooves 49 in the axial direction of the rotating shaft 12, other than the back pressure supply groove 49a that is located at the bottom in the gravity direction Z, among the plurality of back pressure supply grooves 49.

[0094] The discharge hole 82 may be located above the rotary shaft 12 in the gravity direction Z or at the same height as the rotary shaft 12 and overlap with the back pressure supply groove 49 in the axial direction of the rotary shaft 12 . The back pressure supply groove 49 does not have to be a linear groove extending along the radial direction of the plate 80, as long as it can supply the refrigerant in the first back pressure space S41 to the second back pressure space S42 by connecting the first back pressure space S41 and the second back pressure space S42. The back pressure supply groove 49 may have, for example, a portion extending along the radial direction of the plate 80 and a portion extending in the circumferential direction of the plate 80.

[0095] The refrigerant discharged to the discharge chamber S2 may be introduced into the back pressure chamber S4 instead of the refrigerant compressed in the compression chamber S3. The opposing wall disposed on the opposite side of the movable substrate 71 from the fixed substrate 61 does not have to be part of the housing 11. The opposing wall may be a member accommodated within the housing 11.

[0096] The scroll compressor 10 does not have to be mounted on the vehicle in an orientation in which the axial direction of the rotation shaft 12 is perpendicular to the direction of gravity Z. The mounting direction of the scroll compressor 10 on the vehicle may be changed as appropriate.

[0097] The scroll compressor 10 does not have to be a type that is driven by the electric motor 13. The scroll compressor 10 may be a type that is driven by, for example, a vehicle engine.

[0098] The scroll compressor 10 does not have to be mounted on a vehicle. The scroll compressor 10 does not have to be used in a vehicle air conditioning system. The scroll compressor 10 may be mounted on, for example, a fuel cell vehicle. The scroll compressor 10 may compress air, which is a fluid to be supplied to a fuel cell, using the compression unit 14.

[0099] [Note] The technical ideas that can be understood from the above-described embodiments and modifications will be described below. [1] A housing having a suction chamber into which a fluid is drawn, a rotary shaft rotatably supported relative to the housing, a fixed scroll having a fixed base plate, a fixed spiral wall erected from the fixed base plate, and a cylindrical fixed outer peripheral wall erected from the fixed base plate and surrounding the fixed spiral wall, and fixed to the housing, a movable base plate facing the fixed base plate, and a movable scroll having a movable spiral wall erected from the movable base plate toward the fixed base plate and engaging with the fixed spiral wall, the movable scroll being disposed inside the fixed outer peripheral wall and revolving relative to the fixed scroll as the rotary shaft rotates, an opposing wall disposed opposite the movable base plate on the opposite side to the fixed base plate, and an annular plate interposed between the movable base plate and the opposing wall, the fixed outer peripheral wall, the movable scroll, and the plate defining a space in which the fluid flows in from the suction chamber. a back pressure chamber having a suction pressure space extending from the opposing wall toward the fixed scroll, a back pressure chamber formed by a suction pressure chamber recessed from an opposing surface of the opposing wall facing the plate, a first back pressure space defined by the orbiting scroll and the opposing wall, and a second back pressure space defined by the plate and the back pressure chamber recessed, the back pressure chamber biasing the orbiting scroll toward the fixed scroll, a back pressure supply groove recessed from the opposing surface, connecting the first back pressure space and the second back pressure space, and supplying the fluid in the first back pressure space to the second back pressure space, and a discharge hole penetrating the plate, connecting the second back pressure space and the suction pressure space, and discharging the fluid in the second back pressure space to the suction pressure space, wherein at least a portion of the discharge hole overlaps with the back pressure supply groove in the axial direction of the rotary shaft.

[0100] [2] The scroll compressor according to [1], wherein the discharge hole switches between a discharge state in which the discharge hole is connected to the suction pressure space and a non-discharge state in which the discharge hole faces the movable scroll in accordance with the revolution of the movable scroll relative to the fixed scroll.

[0101] [3] The scroll compressor according to [1] or [2], wherein the discharge hole is below the rotating shaft in the direction of gravity and overlaps with the back pressure supply groove in the axial direction of the rotating shaft. [4] The scroll compressor according to any one of [1] to [3], wherein the opposing wall is provided with a plurality of back pressure supply grooves, the plurality of back pressure supply grooves are arranged at intervals in the circumferential direction of the plate, and the discharge hole overlaps with some of the plurality of back pressure supply grooves in the axial direction of the rotating shaft.

[0102] [5] The scroll compressor according to any one of [1] to [4], wherein the back pressure supply groove is a linear groove extending along the radial direction of the plate. [6] The scroll compressor according to any one of [1] to [5], wherein the back pressure chamber has a third back pressure space defined by the movable scroll and the plate and communicating with the first back pressure space. [Explanation of symbols]

[0103] 10...Scroll compressor, 11...Housing, 12...Rotating shaft, 40...Support housing as opposing wall, 40a...End face as opposing surface, 48...Back pressure chamber forming recess, 49...Back pressure supply groove, 60...Fixed scroll, 61...Fixed base plate, 62...Fixed spiral wall, 63...Fixed outer peripheral wall, 70...Moving scroll, 71...Moving base plate, 72...Moving spiral wall, 80...Plate, 82...Discharge hole, K...Suction pressure space, S1...Motor chamber as suction chamber, S4...Back pressure chamber, S41...First back pressure space, S42...Second back pressure space, S43...Third back pressure space, Z...Gravity direction.

Claims

1. a housing having a suction chamber into which fluid is drawn; a rotation shaft rotatably supported relative to the housing; a fixed scroll having a fixed base plate, a fixed spiral wall extending from the fixed base plate, and a cylindrical fixed outer peripheral wall extending from the fixed base plate and surrounding the fixed spiral wall, the fixed scroll being fixed to the housing; a movable scroll disposed inside the fixed outer peripheral wall, the movable scroll having a movable base plate facing the fixed base plate, and a movable spiral wall extending from the movable base plate toward the fixed base plate and engaging with the fixed spiral wall, the movable scroll being adapted to revolve relative to the fixed scroll as the rotary shaft rotates; an opposing wall disposed opposite the movable substrate on the opposite side to the fixed substrate; an annular plate interposed between the movable base plate and the opposing wall; a suction pressure space defined by the fixed outer peripheral wall, the movable scroll, and the plate, into which the fluid flows from the suction chamber; a back pressure chamber forming recess formed in an annular shape and recessed from a surface of the opposing wall facing the plate; a back pressure chamber including a first back pressure space defined by the movable scroll and the opposing wall, and a second back pressure space defined by the plate and the back pressure chamber-forming recess, the back pressure chamber biasing the movable scroll toward the fixed scroll; a back pressure supply groove recessed from the opposing surface, connecting the first back pressure space and the second back pressure space, and supplying the fluid in the first back pressure space to the second back pressure space; a discharge hole that penetrates the plate, that is capable of communicating the second back pressure space with the suction pressure space, and that is capable of discharging the fluid in the second back pressure space to the suction pressure space; A scroll compressor comprising: The scroll compressor, wherein at least a portion of the discharge hole overlaps with the back pressure supply groove in the axial direction of the rotary shaft.

2. 2. The scroll compressor according to claim 1, wherein the discharge hole switches between a discharge state in which the discharge hole communicates with the suction pressure space and a non-discharge state in which the discharge hole faces the movable scroll as the movable scroll revolves relative to the fixed scroll.

3. 2. The scroll compressor according to claim 1, wherein the discharge hole overlaps with the back pressure supply groove in the axial direction of the rotary shaft below the rotary shaft in the direction of gravity.

4. The opposing wall is provided with a plurality of back pressure supply grooves, the back pressure supply grooves are arranged at intervals in the circumferential direction of the plate, The scroll compressor according to claim 1 , wherein the discharge hole overlaps with some of the back pressure supply grooves in the axial direction of the rotary shaft.

5. 2. The scroll compressor according to claim 1, wherein the back pressure supply groove is a linear groove extending along the radial direction of the plate.

6. 2. The scroll compressor according to claim 1, wherein the back pressure chamber includes a third back pressure space defined by the movable scroll and the plate and communicating with the first back pressure space.

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