DOUBLE-HEADED PISTON SWASH PLATE TYPE COMPRESSOR

BACKGROUND OF THE INVENTION

The present invention relates to a double-headed piston swash plate type compressor, in which double-headed piston engaged with a swash plate are reciprocated by a stroke corresponding to the inclination angle of a swash plate.

Such a double-headed piston swash plate type compressor (hereinafter, simply referred to as “compressor”) is disclosed in Japanese Laid-Open Patent Publication No. 5-172052. As shown in FIGS. 7 and 8, the compressor 100 disclosed in the above publication includes a housing 101, which is formed by a cylinder block 102, a front housing member 104, and a rear housing member 105. The front housing member 104 closes the front end of the cylinder block 102 via a valve plate 103a, and the rear housing member 105 closes the rear end of the cylinder block 102 via a valve plate 103b.

A through hole 102h is formed at the center of the cylinder block 102. The through hole 102h receives a rotary shaft 106, which extends through the front housing member 104. The cylinder block 102 has cylinder bores 107 formed about the rotary shaft 106. Each cylinder bore 107 houses a double-headed piston 108. The cylinder block 102 further has a crank chamber 102a. The crank chamber 102a accommodates a tiltable swash plate 109, which rotates when receiving drive force from the rotary shaft 106. Each double-headed piston 108 is engaged with the swash plate 109 via shoes 110. The front housing member 104 and the rear housing member 105 have suction chambers 104a, 105a and discharge chambers 104b, 105b, which communicate with the cylinder bores 107.

An actuator 111 is arranged at the rear end of the through hole 102h of the cylinder block 102. The actuator 111 accommodates in it the rear end of the rotary shaft 106. The interior of the actuator 111 is slidable along the rear end of the rotary shaft 106. The periphery of the actuator 111 is slidable along the through hole 102h. A pressing spring 112 is located between the actuator 111 and the valve plate 103b. The pressing spring 112 urges the actuator 111 toward the front end of the rotary shaft 106. The urging force of the pressing spring 112 is determined by the balance with the pressure in the crank chamber 102a.

A part of the through hole 102h that is rearward of the actuator 111 communicates with a pressure regulating chamber 117 (control pressure chamber), which is formed in the rear housing member 105, via a through hole. The pressure regulating chamber 117 is connected to the discharge chamber 105b via a pressure regulating circuit 118. A pressure control valve 119 is arranged in the pressure regulating circuit 118. The amount of movement of the actuator 111 is adjusted by the pressure in the pressure regulating chamber 117.

A first coupling body 114 is arranged in front of the actuator 111 with a thrust bearing 113 in between. The rotary shaft 106 extends through the first coupling body 114. The interior of the first coupling body 114 is slidable along the rotary shaft 106. The first coupling body 114 is designed to slide along the axis of the rotary shaft 106 when the actuator 111 slides. The first coupling body 114 has a first arm 114a, which extends outward from the periphery. The first arm 114a has a first pin guiding groove 114h, which is formed by cutting out a part diagonally with respect to the axis of the rotary shaft 106.

A second coupling body 115 (drive force transmitting member) is arranged in front of the swash plate 109. The second coupling body 115 is fixed to the rotary shaft 106 to rotate integrally with the rotary shaft 106. The second coupling body 115 has a second arm 115a, which extends outward from the periphery and is located at a symmetrical position with respect to the first arm 114a. The second arm 115a has a second pin guiding groove 115h, which extends through the second arm 115a in a diagonal direction with respect to the axis of the rotary shaft 106.

Two first supporting lobes 109a, which extend toward the first arm 114a, are formed on a surface of the swash plate 109 that faces the first coupling body 114. The first arm 114a is located between the two first supporting lobes 109a. The two first supporting lobes 109a and the first arm 114a are pivotally coupled to each other by a first coupling pin 114p, which extends through first pin guiding groove 114h.

Two second supporting lobes 109b, which extend toward the second arm 115a, are formed on a surface of the swash plate 109 that faces the second coupling body 115. The second arm 115a is located between the second supporting lobes 109b. The two second supporting lobes 109b and the second arm 115a are pivotally coupled to each other by a second coupling pin 115p, which extends through second pin guiding groove 115h. The swash plate 109 receives drive force from the rotary shaft 106 via the second coupling body 115 to be rotated.

To decrease the displacement of the compressor 100, the pressure in the pressure regulating chamber 117 is lowered by closing the pressure control valve 119. This causes the pressure in the crank chamber 102a to be greater than the pressure in the pressure regulating chamber 117 and the urging force of the pressing spring 112. Accordingly, the actuator 111 is moved toward the valve plate 103b as shown in FIG. 7. At this time, the first coupling body 114 is pushed toward the actuator 111 by the pressure in the crank chamber 102a. The movement of the first coupling body 114 causes the first coupling pin 114p to be guided by the first pin guiding groove 114h, so that first supporting lobes 109a rotate counterclockwise. As the first supporting lobes 109a rotate, the second supporting lobes 109b rotate counterclockwise, so that the second coupling pin 115p is guided by the second pin guiding groove 115h. This reduces the inclination angle of the swash plate 109 and thus reduces the stroke of the double-headed pistons 108. Accordingly, the displacement is decreased.

In contrast, to increase the displacement of the compressor 100, the pressure control valve 119 is opened to introduce high-pressure gas (control gas) from the discharge chamber 105b to the pressure regulating chamber 117 via the pressure regulating circuit 118, thereby increasing the pressure in the pressure regulating chamber 117. This causes the pressure in the pressure regulating chamber 117 and the urging force of the pressing spring 112 to be greater than the pressure in the crank chamber 102a. Accordingly, the actuator 111 is moved toward the swash plate 109 as shown in FIG. 8.

At this time, the first coupling body 114 is pushed by the actuator 111 and moved toward the second coupling body 115. The movement of the first coupling body 114 causes the first coupling pin 114p to be guided by the first pin guiding groove 114h, so that first supporting lobes 109a rotate clockwise. As the first supporting lobes 109a rotate, the second supporting lobes 109b rotate clockwise, so that the second coupling pin 115p is guided by the second pin guiding groove 115h. This increases the inclination angle of the swash plate 109 and thus increases the stroke of the double-headed pistons 108. Accordingly, the displacement is increased.

In the structure of the compressor 100 of the above publication, each cylinder bore 107 houses a double-headed piston 108, and the double-headed pistons 108 linearly reciprocate in a region radially outward of the rotary shaft 106 in the cylinder block 102. Thus, in the cylinder block 102, the space for accommodating the second coupling body 115, the actuator 111, and the first coupling body 114 is limited to be inward in the radial direction of the rotary shaft 106 in relation to the region in which the double-headed pistons 108 perform linear reciprocation.

The second coupling body 115 is aligned with the actuator 111 and the first coupling body 114 along the axis of the rotary shaft 106 with the swash plate 109 in between. Therefore, the pressure regulating chamber 117, into which high-pressure gas is introduced to control the movement of the actuator 111 and the first coupling body 114, needs to be formed on the opposite side of the swash plate 109 from the second coupling body 115 in the axial direction of the rotary shaft 106. As a result, the second coupling body 115 is arranged on one side of the swash plate 109 in the axial direction of the rotary shaft 106. Further, the actuator 111, the first coupling body 114, and the pressure regulating chamber 117 are located on the other side of the swash plate 109 in the axial direction of the rotary shaft 106. This increases the size of the compressor 100 in the axial direction of the rotary shaft 106.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide a double-headed piston swash plate type compressor that is capable of reducing its size in the axial direction of the rotary shaft.

To achieve the foregoing objective and in accordance with one aspect of the present invention, a double-headed piston swash plate type compressor is provided that includes a pair of cylinder blocks, a first cylinder bore, a second cylinder bore, a double-headed piston, a rotary shaft, a drive force transmitting member, a swash plate, a movable body, and a control pressure chamber. The cylinder blocks form a housing and have a crank chamber. The first cylinder bore and the second cylinder bore are respectively formed in the two cylinder blocks to form a pair. The double-headed piston is reciprocally received in the first and second cylinder bores. The rotary shaft is rotationally supported by the housing. The drive force transmitting member is accommodated in the crank chamber and fixed to the rotary shaft to rotate integrally with the rotary shaft. The swash plate is accommodated in the crank chamber and rotated by a drive force of the rotary shaft via the drive force transmitting member. An inclination angle of the swash plate relative to the rotary shaft is changeable. The drive force transmitting member has a link portion that guides the swash plate to change the inclination angle. The double-headed piston is engaged with the swash plate and is reciprocated by a stroke that corresponds to the inclination angle of the swash plate. The movable body is coupled to the swash plate and capable of changing the inclination angle of the swash plate. The control pressure chamber is defined by the movable body and the drive force transmitting member. The drive force transmitting member and the movable body are arranged on one side of the swash plate in an axial direction of the rotary shaft. Control gas is introduced into the control pressure chamber to change an internal pressure of the control pressure chamber, so that the movable body is moved in the axial direction of the rotary shaft. The movable body includes a bottom portion, through which the rotary shaft extends, and a cylindrical portion, which extends from the bottom portion in the axial direction of the rotary shaft to surround the rotary shaft. The cylindrical portion is permitted to move in the axial direction of the rotary shaft while sliding along a part of the drive force transmitting member, so that the inclination angle of the swash plate is changed in accordance with changes in the internal pressure of the control pressure chamber.

Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a cross-sectional side view illustrating a double-headed piston swash plate type compressor according to one embodiment;

FIG. 2 is a diagram showing the arrangement of a control pressure chamber, a pressure adjusting chamber, a suction chamber, and a discharge chamber;

FIG. 3 is a cross-sectional side view illustrating the double-headed piston swash plate type compressor when the inclination angle of the swash plate is minimized;

FIG. 4 is a cross-sectional side view partially showing the double-headed piston swash plate type compressor when the swash plate is at a predetermined inclination angle;

FIG. 5 is a cross-sectional side view illustrating a double-headed piston swash plate type compressor according to another embodiment when the inclination angle of the swash plate is maximized;

FIG. 6 is a cross-sectional side view illustrating the double-headed piston swash plate type compressor when the inclination angle of the swash plate is minimized;

FIG. 7 is a cross-sectional side view illustrating a conventional variable displacement swash plate type compressor; and

FIG. 8 is a cross-sectional side view illustrating the conventional variable displacement swash plate type compressor when the inclination angle of the swash plate is maximized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment will now be described with reference to FIGS. 1 to 4. A double-headed piston swash plate type compressor 10 (hereinafter, simply referred to as “compressor”) is mounted in a vehicle.

As shown in FIG. 1, the compressor 10 includes a housing 11, which is formed by a first cylinder block 12 located on the front side (first side) and a second cylinder block 13 located on the rear side (second side). The first and second cylinder blocks 12, 13 are joined to each other. The housing 11 further includes a front housing member 14 joined to the first cylinder block 12 and a rear housing member 15 joined to the second cylinder block 13. The first cylinder block 12 and the second cylinder block 13 are cylinder blocks that are part of the housing 11. The first cylinder block 12 and the second cylinder block 13 form a pair.

A first valve plate 16 is arranged between the front housing member 14 and the first cylinder block 12. Further, a second valve plate 17 is arranged between the rear housing member 15 and the second cylinder block 13.

A suction chamber 14a and a discharge chamber 14b are defined between the front housing member 14 and the first valve plate 16. The discharge chamber 14b is located radially outward of the suction chamber 14a. Likewise, a suction chamber 15a and a discharge chamber 15b are defined between the rear housing member 15 and the second valve plate 17.

Additionally, a pressure adjusting chamber 15c is formed in the rear housing member 15. The pressure adjusting chamber 15c is located at the center of the rear housing member 15, and the suction chamber 15a is located radially outward of the pressure adjusting chamber 15c. The discharge chamber 15b is located radially outward of the suction chamber 15a. The discharge chamber 14b, 15b are connected to each other through a discharge passage (not shown). The discharge passage is in turn connected to an external refrigerant circuit (not shown).

The first valve plate 16 has suction ports 16a connected to the suction chamber 14a and discharge ports 16b connected to the discharge chamber 14b. The second valve plate 17 has suction ports 17a connected to the suction chamber 15a and discharge ports 17b connected to the discharge chamber 15b. A suction valve mechanism (not shown) is arranged in each of the suction ports 16a, 17a. A discharge valve mechanism (not shown) is arranged in each of the discharge ports 16b, 17b.

A rotary shaft 21 is rotationally supported in the housing member 11. A part of the rotary shaft 21 on the front side (first side) extends through a shaft hole 12h, which is formed to extend through the first cylinder block 12. Specifically, the front part of the rotary shaft 21 refers to a part of the rotary shaft 21 that is located on the first side in the direction along the axis L of the rotary shaft 21 (the axial direction of the rotary shaft 21). The front end of the rotary shaft 21 is located in the front housing member 14. A part of the rotary shaft 21 on the rear side (second side) extends through a shaft hole 13h, which is formed in the second cylinder block 13. Specifically, the rear part of the rotary shaft 21 refers to a part of the rotary shaft 21 that is located on the second side in the direction in which the axis L of the rotary shaft 21 extends. The rear end of the rotary shaft 21 is located in the pressure adjusting chamber 15c.

The front part of the rotary shaft 21 is rotationally supported by the first cylinder block 12 at the shaft hole 12h. The rear part of the rotary shaft 21 is rotationally supported by the second cylinder block 13 at the shaft hole 13h. A sealing device 22 of lip seal type is located between the front housing member 14 and the rotary shaft 21.

In the housing 11, the first cylinder block 12 and the second cylinder block 13 define a crank chamber 24. A swash plate 23 is accommodated in the crank chamber 24. The swash plate 23 receives drive force from the rotary shaft 21 to be rotated. The swash plate 23 is also tiltable along the axis L of the rotary shaft 21 with respect to the rotary shaft 21. The swash plate 23 has an insertion hole 23a, through which the rotary shaft 21 can extends. The swash plate 23 is assembled to the rotary shaft 21 by inserting the rotary shaft 21 into the insertion hole 23a.

The first cylinder block 12 has first cylinder bores 12a (only one of the first cylinder bores 12a is illustrated in FIG. 1), which extend along the axis of the first cylinder block 12 and are arranged about the rotary shaft 21. Each first cylinder bore 12a is connected to the suction chamber 14a via the corresponding suction port 16a and is connected to the discharge chamber 14b via the corresponding discharge port 16b. The second cylinder block 13 has second cylinder bores 13a (only one of the second cylinder bores 13a is illustrated in FIG. 1), which extend along the axis of the second cylinder block 13 and are arranged about the rotary shaft 21. Each second cylinder bore 13a is connected to the suction chamber 15a via the corresponding suction port 17a and is connected to the discharge chamber 15b via the corresponding discharge port 17b. The first cylinder bores 12a and the second cylinder bores 13a are arranged to make front-rear pairs. Each pair of the first cylinder bore 12a and the second cylinder bore 13a accommodates a double-headed piston 25, while permitting the piston 25 to reciprocate in the front-rear direction.

Each double-headed piston 25 is engaged with the periphery of the swash plate 23 with two shoes 26. The shoes 26 convert rotation of the swash plate 23, which rotates with the rotary shaft 21, to linear reciprocation of the double-headed pistons 25. In each first cylinder bore 12a, a first compression chamber 20a is defined by the double-headed piston 25 and the first valve plate 16. In each second cylinder bore 13a, a second compression chamber 20b is defined by the double-headed piston 25 and the second valve plate 17.

The first cylinder block 12 has a first large diameter hole 12b, which is continuous with the shaft hole 12h and has a larger diameter than the shaft hole 12h. The first large diameter hole 12b communicates with the crank chamber 24. The crank chamber 24 and the suction chamber 14a are connected to each other by a suction passage 12c, which extends through the first cylinder block 12 and the first valve plate 16.

The second cylinder block 13 has a second large diameter hole 13b, which is continuous with the shaft hole 13h and has a larger diameter than the shaft hole 13h. The second large diameter hole 13b communicates with the crank chamber 24. The crank chamber 24 and the suction chamber 15a are connected to each other by a suction passage 13c, which extends through the second cylinder block 13 and the second valve plate 17.

A suction inlet 13s is formed in the peripheral wall of the second cylinder block 13. The suction inlet 13s is connected to the external refrigerant circuit. Refrigerant gas is drawn into the crank chamber 24 from the external refrigerant circuit via the suction inlet 13s and is then drawn in to the suction chambers 14a, 15a via the suction passages 12c, 13c. The suction chambers 14a, 15a and the crank chamber 24 are therefore in a suction pressure zone. The pressure in the suction chambers 14a, 15a and the pressure in the crank chamber 24 are substantially equal to each other.

The rotary shaft 21 has an annular flange portion 21f, which extends in the radial direction. The flange portion 21f is arranged in the first large diameter hole 12b. With respect to the axial direction the rotary shaft 21, a thrust bearing 27a is arranged between the flange portion 21f and the first cylinder block 12.

A drive force transmitting member 31 is fixed to the rotary shaft 21 to be rotational integrally with the rotary shaft 21. The drive force transmitting member 31 is located on the rotary shaft 21 and between the flange portion 21f and the swash plate 23. The drive force transmitting member 31 includes an annular main body 31a and a link portion 31c, which projects toward the swash plate 23 from an end face of the main body 31a that faces the swash plate 23. The link portion 31c guides the swash plate 23 to change the inclination angle. An outer circumferential surface 311c of the link portion 31c is curved to be arcuate and located on the same circumferential surface as the outer circumferential surface 311a of the main body 31a. The outer circumferential surface 311a of the main body 31a and the outer circumferential surface 311c of the link portion 31c extend along the axis L of the rotary shaft 21. The link portion 31c has an insertion hole 31h for receiving a columnar first pin 41. The insertion hole 31h has an elongated shape that extends linearly such that the insertion hole 31h approaches the rotary shaft 21 as the distance from the distal end of the link portion 31c decreases.

Further, the swash plate 23 has a coupling portion 23c on the upper side (upper side as viewed in FIG. 1). The coupling portion 23c protrudes toward the link portion 31c of the drive force transmitting member 31. The coupling portion 23c has a circular insertion hole 23d for receiving the first pin 41. The first pin 41 couples the link portion 31c of the drive force transmitting member 31 to the coupling portion 23c of the swash plate 23. This allows the drive force of the rotary shaft 21 to be transmitted to the swash plate 23 via the drive force transmitting member 31, so that the swash plate 23 rotates. The first pin 41 is press fitted to the insertion holes 23d to be bound to the coupling portion 23c of the swash plate 23 and slidably held by the insertion hole 31h.

A movable body 32 is located between the flange portion 21f and the drive force transmitting member 31. The movable body 32 is movable along the axis L of the rotary shaft 21 with respect to the drive force transmitting member 31. Therefore, the drive force transmitting member 31 and the movable body 32 are accommodated in a space of the first cylinder block 12 and the second cylinder block 13 that is inward in the radial direction of the rotary shaft 21 of the region where the double-headed pistons 25 reciprocate. The drive force transmitting member 31 and the movable body 32 are located on the front side (on one side) of the swash plate 23 in the axial direction of the rotary shaft 21.

The movable body 32 is formed by an annular bottom portion 32a and a cylindrical portion 32b. An insertion hole 32e is formed in the bottom portion 32a to receive the rotary shaft 21. The cylindrical portion 32b extends along the axis L of the rotary shaft 21 from the peripheral edge of the bottom portion 32a and surrounds the rotary shaft 21. The cylindrical portion 32b is permitted to move along the axis L of the rotary shaft 21 while an inner circumferential surface 321b of the cylindrical portion 32b slides along the outer circumferential surface 311a of the main body 31a of the drive force transmitting member 31 and the outer circumferential surface 311c of the link portion 31c. Thus, a part of the drive force transmitting member 31 and a part of the movable body 32 in the axial direction of the rotary shaft 21 overlap with each other in the radial direction of the rotary shaft 21. The movable body 32 is caused to rotate integrally with the rotary shaft 21 by the drive force transmitting member 31. The clearance between the inner circumferential surface 321b of the cylindrical portion 32b and the main body 31a of the drive force transmitting member 31 is sealed with a sealing member 33.

The bottom portion 32a has a protrusion 32f at a position where the rotary shaft 21 is received. The protrusion 32f protrudes toward the drive force transmitting member 31 and along the axis L of the rotary shaft 21. An annular holding groove 32d is formed in the inner circumferential surface of the protrusion 32f. The holding groove 32d holds a sealing member 34, which seals the boundary between the insertion hole 32e and the rotary shaft 21. The drive force transmitting member 31 has a recess 31f at a part that faces the protrusion 32f. As the movable body 32 moves, the protrusion 32f is received by the recess 31f. The drive force transmitting member 31 and the movable body 32 define a control pressure chamber 35.

A first in-shaft passage 21a is formed in the rotary shaft 21. The first in-shaft passage 21a extends along the axis L of the rotary shaft 21. The rear end of the first in-shaft passage 21a is opened to the interior of the pressure adjusting chamber 15c. A second in-shaft passage 21b is formed in the rotary shaft 21. The second in-shaft passage 21b extends in the radial direction of the rotary shaft 21. One end of the second in-shaft passage 21b communicates with the first in-shaft passage 21a. The other end of the second in-shaft passage 21b is opened to the interior of the control pressure chamber 35. Accordingly, the control pressure chamber 35 and the pressure adjusting chamber 15c are connected to each other by the first in-shaft passage 21a and the second in-shaft passage 21b.

As shown in FIG. 2, the pressure adjusting chamber 15c and the suction chamber 15a are connected to each other by the bleed passage 36. The bleed passage 36 has an orifice 36a, which restricts the flow rate of refrigerant gas flowing in the bleed passage 36. The pressure adjusting chamber 15c and the discharge chamber 15b are connected to each other by a supply passage 37. An electromagnetic control valve 37s is arranged in the supply passage 37. The control valve 37s is capable of adjusting the opening degree of the supply passage 37 based on the pressure in the suction chamber 15a. The control valve 37s adjusts the flow rate of refrigerant gas flowing in the supply passage 37.

Refrigerant gas is introduced to the control pressure chamber 35 from the discharge chamber 15b via the supply passage 37, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b. Refrigerant gas is delivered to the suction chamber 15a from the control pressure chamber 35 via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, and the bleed passage 36. The introduction and delivery of refrigerant gas changes the pressure in the control pressure chamber 35. The pressure difference between the control pressure chamber 35 and the crank chamber 24 causes the movable body 32 to move along the axis L of the rotary shaft 21 with respect to the drive force transmitting member 31. Therefore, the refrigerant gas introduced into the control pressure chamber 35 serves as control gas for moving the movable body 32 in the axial direction of the rotary shaft 21.

As shown in FIG. 1, a coupling portion 32c is formed at the distal end of the cylindrical portion 32b of the movable body 32. The coupling portion 32c protrudes toward the swash plate 23. The coupling portion 32c has an insertion hole 32h for receiving a columnar second pin 42. The insertion hole 32h has an elongated shape that extends linearly such that the insertion hole 32h approaches the rotary shaft 21 as the distance from the distal end of the coupling portion 32c decreases. The swash plate 23 has a circular insertion hole 23h for receiving the second pin 42 on the lower side (lower side as viewed in FIG. 1). The second pin 42 couples the coupling portion 32c to the lower part of the swash plate 23. The second pin 42 is press fitted to the insertion holes 23h to be bound to the swash plate 23 and slidably held by the insertion hole 32h.

In the compressor 10 having the above described embodiment, reduction in the opening degree of the control valve 37s reduces the amount of refrigerant gas that is delivered to the control pressure chamber 35 from the discharge chamber 15b via the supply passage 37, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b. Since the refrigerant gas is delivered to the suction chamber 15a from the control pressure chamber 35 via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, and the bleed passage 36, the pressure in the control pressure chamber 35 and the pressure in the suction chamber 15a are substantially equalized. This eliminates the pressure difference between the control pressure chamber 35 and the crank chamber 24. Accordingly, the inner circumferential surface 321b of the cylindrical portion 32b slides along the outer circumferential surface 311a of the main body 31a of the drive force transmitting member 31 and the outer circumferential surface 311c of the link portion 31c, so that the bottom portion 32a approaches the drive force transmitting member 31 with the movable body 32 being guided along the axis L of the rotary shaft 21.

The second pin 42 slides in the insertion hole 32h to approach the rotary shaft 21, and the first pin 41 slides in the insertion hole 31h to approach the rotary shaft 21. As a result, the lower part of the swash plate 23 swings away from the drive force transmitting member 31, while the upper part of the swash plate 23 swings toward the drive force transmitting member 31. This reduces the inclination angle of the swash plate 23 and thus reduces the stroke of the double-headed pistons 25. Accordingly, the displacement is decreased.

When the inclination angle of the swash plate 23 is minimized as shown in FIG. 3, the second pin 42 slides to a position in the insertion hole 32h that is closest to the rotary shaft 21. Likewise, the first pin 41 slides to a position in the insertion hole 31h that is closest to the rotary shaft 21. When the inclination angle of the swash plate 23 reaches the minimum inclination angle, the cylindrical portion 32b of the movable body 32 surrounds the entire drive force transmitting member 31. That is, when the inclination angle of the swash plate 23 reaches the minimum inclination angle, the cylindrical portion 32b of the movable body 32 accommodates the entire drive force transmitting member 31. Further, the protrusion 32f enters the recess 31f as the movable body 32 moves toward the swash plate 23.

In contrast, increase in the opening degree of the control valve 37s increases the amount of refrigerant gas that is delivered to the control pressure chamber 35 from the discharge chamber 15b via the supply passage 37, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b. This substantially equalizes the pressure in the control pressure chamber 35 to the pressure in the discharge chamber 15b. Thus, the pressure difference between the control pressure chamber 35 and the crank chamber 24 is increased. The inner circumferential surface 321b of the cylindrical portion 32b slides along the outer circumferential surface 311a of the main body 31a of the drive force transmitting member 31 and the outer circumferential surface 311c of the link portion 31c. Accordingly, the movable body 32 is moved while being guided along the axis L of the rotary shaft 21 such that the bottom portion 32a is separated away from the drive force transmitting member 31.

The second pin 42 slides in the insertion hole 32h to move away from the rotary shaft 21. Likewise, the first pin 41 slides in the insertion hole 31h to move away from the rotary shaft 21. As a result, the lower part of the swash plate 23 swings to approach the drive force transmitting member 31. In contrast, the upper part of the swash plate 23 swings to move away from the drive force transmitting member 31. This increases the inclination angle of the swash plate 23 and thus increases the stroke of the double-headed pistons 25. Accordingly, the displacement is increased.

When the inclination angle of the swash plate 23 is maximized as shown in FIG. 1, the second pin 42 slides to a position in the insertion hole 32h that is farthest from the rotary shaft 21. Likewise, the first pin 41 slides to a position in the insertion hole 31h that is farthest from the rotary shaft 21. In this manner, the cylindrical portion 32b is permitted to move in the axial direction of the rotary shaft 21 while sliding along the outer circumferential surface 311a of the main body 31a of the drive force transmitting member 31 and the outer circumferential surface 311c of the link portion 31c, so that the inclination angle of the swash plate 23 is changed in accordance with changes in the pressure in the control pressure chamber 35.

Operation of the present embodiment will now be described.

The drive force transmitting member 31 and the movable body 32 are located on the front side of the swash plate 23 in the axial direction of the rotary shaft 21. The drive force transmitting member 31 and the movable body 32 define the control pressure chamber 35. That is, the control pressure chamber 35 is defined by utilizing the drive force transmitting member 31, which is an existing structure. Further, the control pressure chamber 35 is arranged on the front side of the swash plate 23 in the axial direction of the rotary shaft 21. Moreover, a part of the drive force transmitting member 31 and a part of the movable body 32 in the axial direction of the rotary shaft 21 overlap with each other in the radial direction of the rotary shaft 21.

The drive force transmitting member 31 and the movable body 32 are accommodated in a space of the first cylinder block 12 and the second cylinder block 13 that is inward in the radial direction of the rotary shaft 21 of the region where the double-headed pistons 25 reciprocate. According to the above described configuration, the size of the space for accommodating the drive force transmitting member 31 and the movable body 32 is minimized in the axial direction of the rotary shaft 21.

The compressor described above in the Background of the Invention section includes the drive force transmitting member located on the front side of the swash plate in the axial direction of the rotary shaft, and the movable body and the control pressure chamber are arranged on the rear side of the swash plate in the axial direction of the rotary shaft. Compared to the conventional compressor having such a configuration, the compressor 10 of the present embodiment, which has the above described configuration, has a reduced size in the axial direction of the rotary shaft 21.

For example, the swash plate 23 of the compressor 10 is at a certain inclination angle in FIG. 4. The inclination angle in FIG. 4 is greater than the minimum inclination angle and smaller than the maximum inclination angle. When the inclination angle of the swash plate 23 is changed from the certain inclination angle, the movable body 32 is moved away from the swash plate 23 due to the pressure difference between the control pressure chamber 35 and the crank chamber 24.

At the contacting point between the second pin 42 and the coupling portion 32c, a force F1 along the normal line acts on the coupling portion 32c. The direction of the force F1 is a direction away from the movable body 32 and intersects the moving direction of the movable body 32 (the axial direction of the rotary shaft 21). The force F1 is resolved into a force F1y, which has a component in a direction perpendicular to the moving direction of the movable body 32 (the vertical direction), and a force F1x, which has a component in the moving direction of the movable body 32 (the horizontal direction). The force F1y, which has a component in a direction perpendicular to the moving direction of the movable body 32, acts on the coupling portion 32c in a direction away from the rotary shaft 21. Therefore, the force F1y, which has a component in a direction perpendicular to the moving direction of the movable body 32, acts to tilt the movable body 32 relative to the moving direction of the movable body 32 via the coupling portion 32c.

According to the preset embodiment, the outer circumferential surface 311a of the main body 31a and the outer circumferential surface 311c of the link portion 31c extend along the axis L of the rotary shaft 21. That is, the outer circumferential surface 311a of the main body 31a and the outer circumferential surface 311c of the link portion 31c extend parallel with the axis L of the rotary shaft 21. Accordingly, the inner circumferential surface 321b of the cylindrical portion 32b contacts the outer circumferential surface 311c of the link portion 31c in addition to the outer circumferential surface 311a of the main body 31a of the drive force transmitting member 31.

Therefore, compared to a case in which the inner circumferential surface 321b of the cylindrical portion 32b contacts only the outer circumferential surface 311a of the main body 31a, the area of contact between the cylindrical portion 32b and the drive force transmitting member 31 is increased. Thus, when the inclination angle of the swash plate 23 is changed, the movable body 32 is prevented from being tilted relative to the moving direction even if the force F1y, which acts to tilt the movable body 32 relative to the moving direction, acts on the movable body 32. As a result, the inclination angle of the swash plate 23 is changed smoothly.

The above described embodiment provides the following advantages.

(1) The drive force transmitting member 31 and the movable body 32 are located on the front side of the swash plate 23 in the axial direction of the rotary shaft 21. The drive force transmitting member 31 and the movable body 32 define a control pressure chamber 35. According to this configuration, the control pressure chamber 35 is defined by utilizing the drive force transmitting member 31, which is an existing structure, and the control pressure chamber 35 is located on the front side of the swash plate 23 in the axial direction of the rotary shaft 21.

Further, the cylindrical portion 32b is permitted to move in the axial direction of the rotary shaft 21 while sliding along the outer circumferential surface 311a of the main body 31a and the outer circumferential surface 311c of the link portion 31c, so that the inclination angle of the swash plate 23 is changed in accordance with changes in the pressure in the control pressure chamber 35. That is, a part of the drive force transmitting member 31 and a part of the movable body 32 in the axial direction of the rotary shaft 21 overlap with each other in the radial direction of the rotary shaft 21. The drive force transmitting member 31 and the movable body 32 are accommodated in a space of the first cylinder block 12 and the second cylinder block 13 that is inward in the radial direction of the rotary shaft 21 of the region where the double-headed pistons 25 reciprocate. According to the above described configuration, it is possible to minimize the size of the space for accommodating the drive force transmitting member 31 and the movable body 32 in the axial direction of the rotary shaft 21.

(2) The drive force transmitting member 31 is surrounded by the cylindrical portion 32b. This configuration suppresses the temperature increase in the crank chamber 24 caused when lubricant that flows together with refrigerant gas in the crank chamber 24 is agitated by the drive force transmitting member 31, which rotates integrally with the rotary shaft 21.

(3) The bottom portion 32a has a protrusion 32f at a position where the rotary shaft 21 is received. The protrusion 32f protrudes toward the drive force transmitting member 31 and along the axis L of the rotary shaft 21. Further, the holding groove 32d is formed in the inner circumferential surface of the protrusion 32f to hold the sealing member 34, which seals the boundary between the insertion hole 32e and the rotary shaft 21. The drive force transmitting member 31 has a recess 31f at a part that faces the protrusion 32f. As the movable body 32 moves, the protrusion 32f is received by the recess 31f.

This configuration reduces the size of the movable body 32 in the axial direction of the rotary shaft 21 compared to a case in which, to form the holding groove 32d for holding the sealing member 34, a protrusion is formed that protrudes from a part of the bottom portion 32a that receives the rotary shaft 21 and in the axial direction of the rotary shaft 21 is formed in the opposite direction from the drive force transmitting member 31.

Further, compared to a case in which the recess 31f is not formed in a part of the drive force transmitting member 31 that faces the protrusion 32f, the distance between the movable body 32 and the drive force transmitting member 31 is reduced by the amount by which the protrusion 32f enters the recess 31f as the movable body 32 moves. As a result, the size of the compressor 10 is further reduced in the axial direction of the rotary shaft 21.

(4) The outer circumferential surface 311a of the main body 31a and the outer circumferential surface 311c of the link portion 31c extend along the axis L of the rotary shaft 21. This configuration maximizes the contacting area between the drive force transmitting member 31 and the cylindrical portion 32b. Thus, when the inclination angle of the swash plate 23 is changed, the movable body 32 is prevented from being tilted relative to the moving direction even if the force F1y, which acts to tilt the movable body 32 relative to the moving direction, acts on the movable body 32. Therefore, the inclination angle of the swash plate 23 is changed smoothly.

(5) The control pressure chamber 35 is defined by utilizing the drive force transmitting member 31, which is an existing structure. According to this configuration, a member that defines the control pressure chamber 35 together with the movable body 32 does not need to be accommodated in a space of the first cylinder block 12 and the second cylinder block 13 that is inward in the radial direction of the rotary shaft 21 of the region where the double-headed pistons 25 reciprocate.

This minimizes the number of components accommodated in a space of the first cylinder block 12 and the second cylinder block 13 that is inward in the radial direction of the rotary shaft 21 of the region where the double-headed pistons 25 reciprocate. This prevents, inside the first cylinder block 12 and the second cylinder block 13, the size of the compressor 10 from being increased in the axial direction of the rotary shaft 21 by the space for accommodating an additional member when the number of components is increased in the space that is inward in the radial direction of the rotary shaft 21 of the region in which the double-headed pistons 25 reciprocate.

The above described embodiment may be modified as follows.

As illustrated in FIGS. 5 and 6, the drive force transmitting member 31 may include two arms 31A, which serve as a link portion and extend toward the swash plate 23, and the swash plate 23 may have a protrusion 23A extending toward the drive force transmitting member 31. The protrusion 23A is inserted between the two arms 31A and is movable along the space between the arms 31A while being held between the arms 31A.

A cam surface 31B is formed at the bottom between the arms 31A. The protrusion 23A is slidable along the cam surface 31B. The swash plate 23 is permitted to tilt in the axial direction of the rotary shaft 21 by cooperation of the protrusion 23A between the arms 31A and the cam surface 31B. The drive force of the rotary shaft 21 is transmitted to the protrusion 23A via the two arms 31A so that the swash plate 23 rotates. When the swash plate 23 is tilted toward the axis L of the rotary shaft 21, the protrusion 23A slides along the cam surface 31B.

In the illustrated embodiment, the outer circumferential surface 311c of the link portion 31c does not necessarily need to be located on the same circumferential surface as the outer circumferential surface 311a of the main body 31a. For example, the outer circumferential surface 311c of the link portion 31c may be located inward of the outer circumferential surface 311a of the main body 31a in the radial direction of the rotary shaft 21. In this case, the cylindrical portion 32b is permitted to move in the axial direction of the rotary shaft 21 while sliding along the outer circumferential surface 311a of the main body 31a, so that the inclination angle of the swash plate 23 is changed in accordance with changes in the pressure in the control pressure chamber 35.

In the illustrated embodiment, to form the holding groove 32d for holding the sealing member 34, a protrusion that protrudes in a direction opposite from the drive force transmitting member 31 may be formed at a part of the bottom portion 32a that receives the rotary shaft 21.

In the illustrated embodiment, the cylindrical portion 32b does not necessarily need to surround the entire drive force transmitting member 31 when the inclination angle of the swash plate 23 reaches the minimum inclination angle.

In the illustrated embodiment, the insertion hole 31h may have, for example, an elongated shape that extends linearly in a direction perpendicular to the axial direction of the rotary shaft 21.

In the illustrated embodiment, the insertion hole 32h may have, for example, an elongated shape that extends linearly in a direction perpendicular to the axial direction of the rotary shaft 21.

In the illustrated embodiment, the insertion hole 31h may have a circular shape, and the insertion hole 23d may have an elongated shape. Further, the first pin 41 may be press fitted to the insertion holes 31h to be bound to the link portion 31c of the drive force transmitting member 31, and slidably held by the insertion hole 23d.

In the illustrated embodiment, the insertion hole 32h may have a circular shape, and the insertion hole 23h may have an elongated shape. Further, the second pin 42 may be press fitted to the insertion holes 32h to be bound to the coupling portion 32c of the movable body 32, and slidably held by the insertion hole 23h.

Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

DOUBLE-HEADED PISTON SWASH PLATE TYPE COMPRESSOR

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CPC

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Priority Claims (1)