SCROLL COMPRESSOR

A scroll compressor includes a rotation shaft, a fixed scroll, a movable scroll, a compression chamber, a shaft support, a housing, a movable member arranged in the shaft support, and a rotation restriction mechanism configured to restrict rotation of the movable scroll. The rotation restriction mechanism includes pins, recesses into which the respective pins are loosely fitted, and the movable member. The movable member includes the pins or the recesses. A switching mechanism is configured to switch the movable member between a state in which movement of the movable member in a radial direction of the rotation shaft is restricted and a state in which the restriction is canceled and the movable member can move freely, which changes a movable range of the movable member in the radial direction so that an orbital radius of the movable scroll is changed.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

Referring toFIGS. 1 to 4, a first embodiment of a scroll compressor (hereinafter referred to as the compressor) will now be described. The compressor is installed in a vehicle and used with a vehicle air-conditioning device.

As shown inFIG. 1, the compressor10includes a housing11made of metal (aluminum in the present embodiment). The housing11includes a cylindrical motor housing member12and a cylindrical discharge housing member13. The motor housing member12includes a closed end and an open end121h(left end as viewed inFIG. 1). The discharge housing member13, which has a closed end, is connected to the open end121hof the motor housing member12. The motor housing member12accommodates a compression unit P, which compresses refrigerant, and an electric motor M, which drives the compression unit P.

The motor housing member12includes an end wall12aand a cylindrical shaft support portion121aprojecting from the central section of the end wall12a.A shaft support21is fixed in the motor housing member12near the open end121h.An insertion hole21aextends through a central section of the shaft support21. The motor housing member12also accommodates a rotation shaft20. The rotation shaft20includes two ends. One end, which faces toward the open end121hof the motor housing member12, is located in the insertion hole21aof the shaft support21and supported by a bearing B1to be rotatable relative to the shaft support21. The other end of the rotation shaft20faces toward the end wall12aof the motor housing member12and is supported by a bearing B2to be rotatable relative to the shaft support portion121a.The bearings B1and B2are plain bearings.

The motor housing member12includes a motor chamber121extending between the shaft support21and the end wall12a.The motor chamber121accommodates the electric motor M that includes a rotor16, which rotates integrally with the rotation shaft20, and a stator17, which surrounds the rotor16and is fixed to the inner surface of the motor housing member12. The rotor16includes a rotor core16a,which is fixed to the rotation shaft20and rotated integrally with the rotation shaft20, and a plurality of permanent magnets16b,which are embedded in the rotor core16a.The stator17includes a stator core17a,which is annular and fixed to the inner surface of the motor housing member12, and coils17b,which are wound around the teeth (not shown) of the stator core17a.Leads R for U, V, and W phases (only one lead shown inFIG. 1) extend from the ends of the coils17bthat face toward the shaft support21.

A fixed scroll22is arranged between the shaft support21and the open end121hof the motor housing member12. The fixed scroll22includes a circular base plate22a,a cylindrically-formed peripheral wall22bprojecting from the periphery of the base plate22a,and a fixed spiral wall22cprojecting from the base plate22aat the inner side of the peripheral wall22b.

An eccentric shaft20aprojects from the end face of the rotation shaft20that faces toward the open end121h.The eccentric shaft20ais eccentric to the rotation axis L of the rotation shaft20. The eccentric shaft20asupports a bushing20b.A movable scroll23is supported by the bushing20bto be rotatable relative to the bushing20b.A bearing B3is arranged between the movable scroll23and the bushing20b.The movable scroll23includes a circular base plate23aand a movable spiral wall23bprojecting from the base plate23atoward the base plate22aof the fixed scroll22.

The fixed spiral wall22cof the fixed scroll22and the movable spiral wall23bof the movable scroll23are engaged with each other. The fixed spiral wall22chas a distal surface in contact with the base plate23aof the movable scroll23. The movable spiral wall23bhas a distal surface in contact with the base plate22aof the fixed scroll22. The base plate22aand the fixed spiral wall22cof the fixed scroll22and the base plate23aand the movable spiral wall23bof the movable scroll23define a compression chamber25.

As shown inFIG. 2, the end surface of the shaft support21that faces the movable scroll23includes an accommodating recess21h.The accommodating recess21haccommodates an annular movable member28surrounding the bushing20b.A clearance C1is formed between the movable member28and the shaft support21in the radial direction of the rotation shaft20. Thus, the movable member28is movable in the radial direction of the rotation shaft20in the range of a distance corresponding to the clearance C1. In the following description, the terms “axial direction”, “radial direction”, and “circumferential direction” refer to the axial direction, the radial direction, and the circumferential direction of the rotation shaft20, respectively.

A rotation restriction mechanism27is arranged between the base plate23aof the movable scroll23and the shaft support21. The rotation restriction mechanism27includes a plurality of circular holes27a,which are recesses arranged in the outer circumferential portion of the end surface of the base plate23aof the movable scroll23, and a plurality of pins27b(only one shown inFIG. 1), which project from the outer circumferential portion of the shaft support21and are loosely fitted into the circular holes27a.The pins27bare integrated with the movable member28.

As shown inFIGS. 2 and 3, the shaft support21includes a plurality of cylindrical valve chambers21bextending in the axial direction. The valve chambers21bare arranged in intervals in the circumferential direction. Each valve chamber21bhas one end facing toward the movable scroll23that opens in the accommodating recess21hand another end facing away from the movable scroll23that is closed by a cover21f,which has the form of a circular plate. The cover21fis coupled to the end surface of the shaft support21that faces toward the end wall12aof the motor housing member12.

Each valve chamber21baccommodates a cylindrical valve body21v.Each valve body21vhas a semispherical distal end that faces toward the movable scroll23. An annular seal21sis arranged in the outer surface of each valve body21v.The seal21sseals the gap between the valve body21vand the valve chamber21band divides the valve chamber21binto a primary void K1and a secondary void K2. The primary void K1is located between the movable scroll23and the secondary void K2.

As shown inFIG. 2, the shaft support21incorporates an electromagnetic switching valve70. In addition, the shaft support21includes a branch passage71extending from the switching valve70to the valve chambers21b.The branch passage71includes a main passage71a,which is in communication with the switching valve70, and an annular passage71b,which extends in the circumferential direction and communicates the main passage71aand the secondary voids K2of the valve chambers21b.

The end surface of the movable member28that faces away from the movable scroll23includes circular fitting recesses28kat positions corresponding to the valve chambers21b.The surface of each fitting recess28kis tapered so that the diameter of the fitting recess28kincreases from the side that faces toward the movable scroll23to the end surface that faces away from the movable scroll23. The movable member28also includes communication passages28rthat extend in the axial direction and are in communication with the corresponding fitting recesses28k.

An annular, flat seat member24is arranged between the movable scroll23and the movable member28. The seat member24includes a peripheral portion held between the fixed scroll22and the shaft support21. The seat member24is fixed positioned relative to the motor housing member12. The seat member24includes communication holes24gthat communicate the corresponding communication passages28rand a gap between the seat member24and the movable scroll23.

As shown inFIG. 1, when the rotation shaft20is driven by the electric motor M and rotated, the movable scroll23, which is coupled to the rotation shaft20by the eccentric shaft20a,orbits about the axis of the fixed scroll22(the rotation axis L of the rotation shaft20) without rotating. The rotation restriction mechanism27prevents rotation of the movable scroll23while permitting the orbital motion. The orbital motion of the movable scroll23reduces the volume of the compression chamber25. Thus, the fixed scroll22and the movable scroll23form a compression unit P that draws in and discharges refrigerant.

The peripheral wall22bof the fixed scroll22and the outermost portion in the movable spiral wall23bof the movable scroll23define a suction chamber31that is in communication with the compression chamber25. The peripheral wall22bof the fixed scroll22has an outer surface including a recess221b.The area surrounded by the recess221band the inner surface of the motor housing member12forms a suction passage32that is connected to the suction chamber31through a through hole221hin the peripheral wall22bof the fixed scroll22. A through hole211, which extends through the peripheral portions of the shaft support21and the cover21f,and a through hole24h,which extends through the peripheral portion of the seat member24, connect the suction passage32to the motor chamber121.

The motor housing member12includes a suction port122connected to an external refrigerant circuit19. Refrigerant (gas) is drawn into the motor chamber121from the external refrigerant circuit19through the suction port122. The refrigerant in the motor chamber121is then sent to the compression chamber25through the through hole211, the through hole24h,the suction passage32, the through hole221h,and the suction chamber31. Accordingly, the motor chamber121, the through hole211, the through hole24h,the suction passage32, the through hole221h,and the suction chamber31form a suction pressure region.

The refrigerant in the compression chamber25is compressed by the orbiting motion (discharging motion) of the movable scroll23, forced through a discharge valve22vof a discharge port22e,and discharged into a discharge chamber131of the discharge housing member13.

A chamber-forming wall41is formed integrally with the discharge housing member13. An oil-separating chamber42is formed between the discharge housing member13and the chamber-forming wall41. The oil-separating chamber42is in communication with the discharge chamber131through a discharge port43formed in the discharge housing member13. The refrigerant in the discharge chamber131is sent to the oil-separating chamber42through the discharge port43.

The oil-separating chamber42accommodates an oil-separating cylinder44. The oil-separating cylinder44includes a large diameter portion441, which is fitted in the oil-separating chamber42, and a small diameter portion442, which has a smaller diameter than the oil-separating chamber42and is located under the large diameter portion441. Refrigerant flows into the oil-separating chamber42through the discharge port43, swirls around the small diameter portion442, and then flows into the oil-separating cylinder44from a lower opening in the small diameter portion442. The refrigerant further flows from the oil-separating cylinder44to the external refrigerant circuit19and then returns to the motor chamber121. Lubricating oil is separated from the refrigerant when the refrigerant swirls around the small diameter portion442. The separated lubricating oil falls into the lower portion of the oil-separating chamber42. Accordingly, the discharge port22e,the discharge chamber131, the discharge port43, and the oil-separating chamber42form a discharge pressure region.

An inverter cover51made of metal (aluminum in the present embodiment) is fixed to the end wall12aof the motor housing member12. The inverter cover51and the end wall12aof the motor housing member12define a chamber that accommodates a motor driving circuit52fixed to the outer surface of the end wall12a.Thus, in the present embodiment, the compression unit P, the electric motor M, and the motor driving circuit52are arranged in this order in the axial direction.

The end wall12aof the motor housing member12includes a through hole12bthat receives a sealing terminal53. The sealing terminal53includes three sets of a metal terminal54and a glass insulator55(only one set shown inFIG. 1). The metal terminals54extend through the motor housing member12to electrically connect the electric motor M to the motor driving circuit52. Each glass insulator55fixes the corresponding metal terminal54to the end wall12aand insulates the metal terminal54from the end wall12a.Each metal terminal54has a first end connected to the motor driving circuit52by a cable (not shown) and a second end extending into the motor housing member12.

An insulative resin cluster block56is fixed to the outer surface of the stator core17a.The cluster block56accommodates three connection terminals56a(only one shown in theFIG. 1). The connection terminals56aelectrically connect the leads R to the metal terminals54. The motor driving circuit52supplies power to the coils17bthrough the metal terminals54, the connection terminals56a,and the leads R. This integrally rotates the rotor16and the rotation shaft20.

As shown inFIG. 2, an annular seal61, which is in contact with the surface of the rotation shaft20, divides the insertion hole21aof the shaft support21into a back pressure chamber62and an accommodating chamber63. The back pressure chamber62is located between the seal61and the movable scroll23. The accommodating chamber63accommodates the bearing B1. A snap ring64is fitted to a section of the insertion hole21aof the shaft support21that is located in the back pressure chamber62. The snap ring64restricts movement of the seal61into the back pressure chamber62.

The movable scroll23and the seat member24include a first oil passage65extending through the movable spiral wall23band the base plate23anear the center of the movable scroll23. The first oil passage65has an end that opens to the compression chamber25and another end that opens to the back pressure chamber62. Some of the refrigerant compressed in the compression chamber25is supplied to the back pressure chamber62through the first oil passage65. The refrigerant supplied to the back pressure chamber62flows through the inner side of the seat member24into the circular holes27a.The pressure of the refrigerant supplied into the back pressure chamber62and the circular holes27apresses the movable scroll23toward the fixed scroll22. Thus, in the present embodiment, the circular holes27aand the back pressure chamber62form a back pressure region located between the movable scroll23and the movable member28in the motor housing member12. The back pressure region applies force to the movable scroll23, and the force presses the movable scroll23against the fixed scroll22.

When refrigerant enters the gap between the seat member24and the movable scroll23, the refrigerant flows to the primary voids K1of the valve chambers21bthrough the corresponding communication holes24gand the communication passages28r.The primary voids K1function as part of the back pressure region due to the pressure of the refrigerant flowing into the primary voids K1.

The switching valve70is in communication with the oil-separating chamber42through the second oil passage68, which extends through the shaft support21, the seat member24, the fixed scroll22, and the discharge housing member13. Further, the switching valve70is in communication with the motor chamber121through a communication passage69formed in the shaft support21and the cover21f.The switching valve70operates so that the secondary voids K2of the valve chambers21bare in communication with the second oil passage68through the branch passage71when the compressor10operates at a high rotation speed and so that the secondary voids K2are in communication with the communication passage69through the branch passage71when the compressor10operates at a low rotation speed. In other words, the switching valve70switches between a state in which the secondary voids K2are in communication with a suction pressure region and a state in which the secondary voids K2are in communication with a discharge pressure region. The suction pressure region is a low pressure region, the pressure of which is lower than that of the primary voids K1. The primary voids K1are part of the back pressure region. The discharge pressure region is a high pressure region, the pressure of which is higher than that of the primary voids K1.

The operation of the first embodiment will now be described.

As shown inFIG. 4, when the compressor10operates at a high rotation speed, the switching valve70brings the secondary voids K2of the valve chambers21binto communication with the second oil passage68through the branch passage71. This allows the lubricating oil flowing in the second oil passage68from the oil-separating chamber42to be sent into the secondary voids K2of the valve chambers21bthrough the switching valve70and the branch passage71. Consequently, the secondary voids K2become part of the discharge pressure region.

The difference between the pressure in the primary voids K1and the pressure in the secondary voids K2moves the valve bodies21vtoward the movable scroll23. The distal end of each valve body21vthat faces toward the movable scroll23is guided by the surface of the corresponding fitting recess28kinto the fitting recess28k.Accordingly, the movable member28is pressed by the valve bodies21vtoward the movable scroll23and received by the seat member24. Thus, the movable member28is held between the valve bodies21vand the seat member24. This restricts movement of the movable member in the radial direction. Further, the engagement between the valve bodies21vand the respective fitting recesses28kalso restricts the radial movement of the movable member28and changes the movable range of the movable member28in the radial direction. Thus, the orbital radius of the movable scroll23is decreased compared to when the restriction of the movable member28is canceled and the movable member28can move freely. As a result, the movable spiral wall23bdoes not contact the fixed spiral wall22cwhen the compressor10operates at a high rotation speed. This reduces noise that would be caused by contact between the fixed spiral wall22cand the movable spiral wall23bduring high speed rotation.

As shown inFIG. 2, when the compressor10operates at a low rotation speed, the switching valve70brings the secondary voids K2of the valve chambers21binto communication with the communication passage69through the branch passage71. This allows the refrigerant in the valve chambers21bto flow into the motor chamber121through the branch passage71, the switching valve70, and the communication passage69. Consequently, the secondary voids K2become part of the suction pressure region.

The difference in the pressure in the primary voids K1and the pressure in the secondary voids K2moves the valve bodies21vaway from the movable scroll23. This releases the movable member28from the valve bodies21vand the seat member24and disengages the valve bodies21vfrom the fitting recesses28kthereby allowing the movable member28to move freely. As a result, the movable range of the movable member28in the radial direction is changed. Thus, the orbital radius of the movable scroll23is increased compared to when the radial movement of the movable member28is restricted. As a result, the movable spiral wall23bis in contact with the fixed spiral wall22cwhen the compressor10operates at low rotation speed. This suppresses leakage of refrigerant from the compression chamber25during low speed rotation. In the present embodiment, the valve chamber21b,the valve body21v,the primary void K1, the secondary void K2, the branch passage71, and the switching valve70form a switching mechanism.

The orbital radius of the movable scroll23is increased or decreased when the bushing20bslides or swings to move in the radial direction relative to the eccentric shaft20aand thereby permit radial movement of the movable scroll23.

The advantage of the first embodiment will now be described.

(1) The movable member28is arranged in the shaft support21. In addition, the pins27b,the circular holes27a,and the movable member28form the rotation restriction mechanism27. The movable member28is switched between a state in which the radial movement of the movable member28is restricted and a state in which the restriction is canceled and the movable member28can move freely. This allows the movable range of the movable member28and the orbital radius of the movable scroll23to be changed. When the compressor10operates at high rotation speed, the radial movement of the movable member28is restricted to reduce the movable range of the movable member28in the radial direction. Thus, the orbital radius of the movable scroll23is decreased so that the movable spiral wall23bdoes not contact the fixed spiral wall22c.This reduces noise that would be caused by contact between the fixed spiral wall22cand the movable spiral wall23bduring high speed rotation. Further, when the compressor10operates at low rotation speed, the restriction of the movable member28is canceled so that the movable member can move freely. This increases the movable range of the movable member28in the radial direction and allows the orbital radius of the movable scroll23to be increased. Thus, the movable spiral wall23bcontacts the fixed spiral wall22c.This suppresses leakage of refrigerant from the compression chamber25during low speed rotation.

(2) The shaft support21includes the valve chambers21b,each accommodating the corresponding valve body21vthat presses the movable member28toward the movable scroll23. Thus, the radial movement of the movable member28can be restricted by moving the valve bodies21vtoward the movable scroll23so that the valve bodies21vpress the movable member28toward the movable scroll23.

(3) The shaft support21includes the switching valve70, which switches between a state in which the secondary voids K2are in communication with the suction pressure region having a lower pressure than the primary voids K1, which function as the back pressure region, and a state in which the secondary voids K2are in communication with the discharge pressure region having a higher pressure than the primary voids K1. When the switching valve70brings the secondary voids K2into communication with the discharge pressure region, the difference between the pressure in the primary voids K1and the pressure in the secondary voids K2moves the valve bodies21vtoward the movable scroll23. Accordingly, the valve bodies21vpress the movable member28toward the movable scroll23and easily restrict the radial movement of the movable member28. Further, when the switching valve70brings the secondary voids K2into communication with the suction pressure region, the difference between the pressure in the primary voids K1and the pressure in the secondary voids K2moves the valve bodies21vaway from the movable scroll23. Thus, the valve bodies21vno longer press the movable member28against the movable scroll23, and the restriction of the radial movement of the rotation shaft20is easily cancelled.

(4) The movable member28includes the communication passages28rthat communicate the back pressure region and the primary voids K1. This ensures that the primary voids K1function as part of the back pressure region and contrasts to a structure in which the movable member28does not include the communication passages28r.Consequently, when the secondary voids K2become part of the discharge pressure region due to actuation of the switching valve70, the difference between the pressure in the primary voids K1and the pressure in secondary voids K2is ensured to move the valve bodies21vtoward the movable scroll23. Further, when the secondary voids K2become part of the suction pressure region due to actuation of the switching valve70, the difference between the pressure in the primary voids K1and the pressure in the secondary voids K2is ensured to move the valve bodies21vaway from the movable scroll23.

(5) The shaft support21includes a plurality of valve chambers21bseparated from one another in the circumferential direction. The shaft support21also includes the branch passage71extending from the switching valve70to the valve chambers21b.This facilitates restriction of the radial movement of the movable member28and contrasts to a structure in which the shaft support21includes only one valve chamber21band the radial movement of the movable member28is restricted by only one valve body21v.

(6) The movable member28includes the fitting recesses28kto which the corresponding valve bodies21vcan be fitted. When the switching valve70brings the secondary voids K2into communication with the discharge pressure region and the difference between the pressure in the primary voids K1and the pressure in the secondary voids K2moves the valve bodies21vtoward the movable scroll23, the valve bodies21vare fitted to the corresponding fitting recesses28k.This further facilitates the restriction of radial movement of the movable member28.

(7) The seat member24is arranged between the movable scroll23and the movable member28. The seat member24is fixed to the motor housing member12and receives the movable member28that is pressed toward the movable scroll23by the valve bodies21v.This facilitates the restriction of radial movement of the movable member28compared to a structure in which the radial movement of the movable member28is restricted by holding the movable member28between the valve bodies21vand the movable scroll23, for example.

(8) Each valve body21vincludes the semispherical distal end that faces toward the movable scroll23. In addition, the surface of each fitting recess28kis tapered so that the diameter of the fitting recess28kincreases from the side that faces toward the movable scroll23to the end surface that faces away from the movable scroll23. Thus, when the difference in the pressure in the primary voids K1and the pressure in the secondary voids K2moves the valve bodies21vtoward the movable scroll23, the distal end of each valve body21vis guided by the surface of the corresponding fitting recess28kand inserted into the fitting recess28k.This facilitates the engagement between the valve body21vand the fitting recess28k.

Second Embodiment

Referring toFIGS. 5 and 6, the second embodiment will now be described. Same reference numerals are given to those components that are the same as the corresponding components of the first embodiment. Such components will not be described in detail.

As shown inFIG. 5, the end surface of the movable member28that faces away from the movable scroll23includes a conical projection81. The conical projection81includes a conical projection surface81athat surrounds the bushing20band has a diameter that decreases as the movable scroll23becomes farther. Further, an annular seal28sis arranged in the outer circumferential surface of the movable member28. The seal28shas an outer surface that is located radially outward from the outer circumferential surface of the movable member28. Accordingly, a clearance C2is formed between the movable member28and the shaft support21in the radial direction. The seal28scan be elastically deformed to allow the movable member28to move in the radial direction in the range of the distance of the clearance C2.

Further, the accommodating recess21haccommodates a tip seal29arranged on the end surface of the movable member28that faces away from the movable scroll23. The tip seal29seals the gap between the shaft support21and the movable member28. In addition, the end surface of the movable member28that faces away from the movable scroll23includes an accommodating groove28gthat can accommodate the tip seal29. The accommodating recess21his divided into a primary void K1and a secondary void K2. The primary void K1is located between the movable scroll23and the secondary void K2, and the secondary void K2is located between the seal28sand the tip seal29.

The shaft support21includes a communication flow passage83that communicates the switching valve70and the secondary void K2. The primary void K1is in communication with the first oil passage65, which is in communication with the back pressure chamber62. Thus, in the second embodiment, the primary void K1functions as part of the back pressure region.

The shaft support21includes a conical recess82on the side that faces the movable member28. The conical recess82includes a conical recess surface82athat surrounds the bushing20band has a diameter that decreases as the movable member28becomes farther. The conical projection81is movable toward and away from the conical recess82.

The operation of the second embodiment will now be described.

As shown inFIG. 6, when the compressor10operates at a high rotation speed, the switching valve70brings the secondary void K2into communication with the communication passage69through the communication flow passage83. This allows the refrigerant in the secondary void K2to flow into the motor chamber121through the communication flow passage83, the switching valve70, and the communication passage69. Consequently, the secondary void K2becomes part of the suction pressure region.

The difference between the pressure in the primary void K1and the pressure in the secondary void K2moves the movable member28away from the movable scroll23. This moves the conical projection81toward the conical recess82and brings the conical projection surface81aand conical recess surface82ainto contact with each other. Thus, the conical projection81is fitted into the conical recess82and thereby restricts the radial movement of the movable member28. This changes the movable range of the movable member28in the radial direction. The orbital radius of the movable scroll23is decreased compared to when the movable member28is not restricted and freely movable. As a result, when the compressor10is operating at a high rotation speed, the movable spiral wall23bis not in contact with the fixed spiral wall22c.This reduces noise that would be caused by contact between the fixed spiral wall22cand the movable spiral wall23bduring high speed rotation.

As shown inFIG. 5, when the compressor10operates at a low rotation speed, the switching valve70brings the secondary void K2into communication with the second oil passage68through the communication flow passage83. This allows the lubricating oil flowing in the second oil passage68from the oil-separating chamber42to flow into the secondary void K2through the switching valve70and the communication flow passage83. Consequently, the secondary void K2becomes part of the discharge pressure region.

The difference between the pressure in the primary void K1and the pressure in the secondary void K2moves the movable member28toward the movable scroll23. This moves the conical projection81away from the conical recess82and allows the movable member28to move freely. Thus, the movable range of the movable member28in the radial direction is changed. The orbital radius of the movable scroll23is increased compared to when the radial movement of the movable member28is restricted. As a result, when the compressor10operates at a low rotation speed, the movable spiral wall23bis in contact with the fixed spiral wall22c.This suppresses leakage of refrigerant from the compression chamber25during low speed rotation. In the present embodiment, the conical projection81, the conical recess82, the primary void K1, the secondary void K2, the communication passage69, and the switching valve70form a switching mechanism.

Accordingly, the second embodiment has the following advantages in addition to advantage (1) of the first embodiment.

(9) The second embodiment does not require the valve chambers21bor the valve bodies21vof the first embodiment and has a simple structure.

In the first embodiment, the movable member28does not have to include the fitting recesses28k.Instead, the valve bodies21vmay be pressed against the end surface of the movable member28that faces away from the movable scroll23to restrict radial movement of the movable member28with the friction produced between the valve bodies21vand the movable member28.

In the first embodiment, the communication passages28rmay be omitted. In this case, the primary voids K1can still become the back pressure region due to the refrigerant flowing into the primary voids K1from the back pressure chamber62through the gap between the movable member28and the shaft support21.

In the first embodiment, the number of the valve chambers21bis not limited.

In the first embodiment, the seat member24may be omitted. The radial movement of the movable member28may be restricted by holding the movable member28between the valve bodies21vand the movable scroll23, for example.

In the first embodiment, the shape of the valve body21vis not limited. For example, the valve body21vmay be spherical.

In the first embodiment, the surface of the fitting recesses28kmay extend in the axial direction, for example.

In the above embodiment, the secondary void K2does not have to be in communication with the suction pressure region or the discharge pressure region as long as the secondary void K2is in communication with a low pressure region that has a lower pressure than the back pressure region or a high pressure region that has a higher pressure than the back pressure region.

The bushing20bmay be fixed to the eccentric shaft20a,and the radial movement of the movable scroll23may be permitted by a gap between the movable scroll23and the bearing B3or a gap between the bushing20band the bearing B3.

In the above embodiments, the secondary void K2receives lubricating oil from the oil-separating chamber42through the second oil passage68. However, the secondary void K2may be in communication with the discharge chamber131so that refrigerant having the discharge pressure is delivered to the secondary void K2.

The movable scroll23may include a plurality of pins that are integrated with the movable scroll23, and the movable member28may include a plurality of circular holes into which the respective pins are loosely fitted.

The present invention may be embodied in a scroll compressor that is directly driven by a driving source such as an engine, instead of being driven by the electric motor M.