VARIABLE DISPLACEMENT SWASH PLATE TYPE COMPRESSOR

Abstract

A variable displacement swash plate type compressor includes a displacement control valve. The displacement control valve includes a drive force transmitting member, a valve member having a first valve body, a valve chamber, which accommodates the first valve body, an accommodating chamber, which communicates with a control pressure chamber, a pressure sensing mechanism, which adjusts the valve opening degree of the first valve body, a communicating chamber, which is located on the opposite side of the pressure sensing mechanism from the valve chamber, and a second valve body, which is located in the pressure sensing mechanism and selectively opens and closes the communicating chamber. When the current supply to the electromagnetic solenoid is stopped and the pressure in the suction pressure zone in the communicating chamber is higher than a predetermined pressure, the pressure sensing mechanism contracts to open the second valve body.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a variable displacement swash plate type compressor, in which pistons engaged with a swash plate are reciprocated by a stroke corresponding to the inclination angle of a swash plate.

Such a compressor is disclosed in Japanese Laid-Open Patent Publication No. 1-190972. The compressor has a housing that accommodates a swash plate and a movable body, which is coupled to the swash plate to alter the inclination angle of the swash plate. A control pressure chamber is formed in the housing. As control gas is introduced to the control pressure chamber, the pressure inside the control pressure chamber is changed. This moves the movable body along the axis of the rotary shaft. As the movable body is moved along the axis of the rotary shaft, the inclination angle of the swash plate is changed.

Specifically, when the pressure in the control pressure chamber is increased, the movable body is moved toward a first end in the axial direction of the rotary shaft. The movement of the movable body increases the inclination angle of the swash plate. When the pressure in the control pressure chamber is lowered, the movable body is moved toward a second end in the axial direction of the rotary shaft. The movement of the movable body decreases the inclination angle of the swash plate. As the inclination angle of the swash plate is reduced, the stroke of the pistons is reduced. Accordingly, the displacement is decreased. In contrast, as the inclination angle of the swash plate is increased, the stroke of the pistons is increased. Accordingly, the displacement is increased. The variable displacement swash plate type compressor has a displacement control valve, which controls the pressure in the control pressure chamber.

In such a variable displacement swash plate type compressor, when the switch of the vehicle air conditioner is turned off and the current supply to the electromagnetic solenoid of the displacement control valve is stopped, changes in the pressure in the suction pressure zone may maintain the inclination angle of the swash plate at an angle greater than the minimum inclination angle. When the air conditioner switch is turned on again and the current supply to the electromagnetic solenoid is resumed, the displacement is abruptly increased. This increases the load on the variable displacement swash plate type compressor. Therefore, the inclination angle of the swash plate is preferably minimized when the air conditioner switch is turned off and the current supply to the electromagnetic solenoid is stopped.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide a variable displacement swash plate type compressor that is capable of minimizing the inclination angle of a swash plate when current supply to the electromagnetic solenoid is stopped and maintaining the minimum inclination angle.

To achieve the foregoing objective and in accordance with one aspect of the present invention, a variable displacement swash plate type compressor is provided that includes a housing having a crank chamber, a swash plate, a piston, a movable body, a control pressure chamber, and a displacement control valve. The swash plate is accommodated in the crank chamber. The swash plate receives a drive force from a rotary shaft to rotate and is capable of changing its inclination angle relative to the rotary shaft. The piston is engaged with the swash plate. The movable body is coupled to the swash plate and changes the inclination angle of the swash plate. The control pressure chamber is defined in the housing by the movable body. Pressure in the control pressure chamber is changed by introducing control gas therein so that the movable body is moved in the axial direction of the rotary shaft. The displacement control valve controls the pressure in the control pressure chamber. The piston is reciprocated by a stroke that corresponds to the inclination angle of the swash plate. The displacement control valve includes a drive force transmitting member, a valve member, a valve chamber, an accommodating chamber, a pressure sensing mechanism, a communicating chamber, and a second valve body. The drive force transmitting member is driven by an electromagnetic solenoid. The valve member has a first valve body. The first valve body adjusts an opening degree of discharge passage that extends from the control pressure chamber to a suction pressure zone. The valve chamber accommodates the first valve body and communicates with the suction pressure zone. The accommodating chamber communicates with the control pressure chamber. The pressure sensing mechanism is accommodated in the accommodating chamber and integrated with the valve member. By sensing a pressure in the suction pressure zone that acts on the valve member, the pressure sensing mechanism extends or contracts in the moving direction of the drive force transmitting member, thereby adjusting the valve opening degree of the first valve body. The communicating chamber is located on the opposite side of the pressure sensing mechanism from the valve chamber and communicates with the suction pressure zone. The second valve body is located in the pressure sensing mechanism and selectively opens and closes the communicating chamber. When a current supply to the electromagnetic solenoid is stopped and the pressure in the suction pressure zone in the communicating chamber is higher than a predetermined pressure, the pressure sensing mechanism contracts in the moving direction of the drive force transmitting member, thereby opening the second valve body.

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 variable displacement swash plate type compressor according to one embodiment;

FIG. 2 is a cross-sectional view of a displacement control valve when the swash plate is at the minimum inclination angle;

FIG. 3 is a cross-sectional view of the displacement control valve when the swash plate is at the maximum inclination angle;

FIG. 4 is a cross-sectional side view illustrating the variable displacement swash plate type compressor when the swash plate is at the maximum inclination angle;

FIG. 5 is a cross-sectional view illustrating the displacement control valve in a state when the pressure in the suction chamber exceeds a predetermined pressure in a state in which current is not supplied to the electromagnetic solenoid;

FIG. 6 is a cross-sectional view illustrating the displacement control valve when current is supplied to the electromagnetic solenoid in a state where the bellows is contracted;

FIG. 7 is a cross-sectional view of the displacement control valve, showing a state in which the valve seat member has been moved toward the communicating chamber;

FIG. 8 is a cross-sectional view showing a displacement control valve according to another embodiment; and

FIG. 9 is a cross-sectional view showing a displacement control valve according to a further embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A variable displacement swash plate type compressor 10 according to one embodiment will now be described with reference to FIGS. 1 to 7. The variable displacement swash plate type compressor 10 is adapted to be used in a vehicle air conditioner.

As shown in FIG. 1, the variable displacement swash plate type 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.

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 discharge chambers 14b, 15b are discharge pressure zones.

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 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. The front end of the rotary shaft 21 is connected to and driven by an external drive source, which is a vehicle engine E in this embodiment, through a power transmission mechanism PT. In the present embodiment, the power transmission mechanism PT is a clutchless mechanism (for example, a combination of a belt and pulleys), which constantly transmits power.

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 also tilts 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. That is, the variable displacement swash plate type compressor 10 of the present embodiment is a double-headed piston swash plate type compressor.

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 into 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 of the rotary shaft 21, a first thrust bearing 27a is arranged between the flange portion 21f and the first cylinder block 12. A cylindrical supporting member 39 is press fitted to a rear portion of the rotary shaft 21. The supporting member 39 has an annular flange portion 39f, which extends in the radial direction. The flange portion 39f is arranged in the second large diameter hole 13b. With respect to the axial direction of the rotary shaft 21, a second thrust bearing 27b is arranged between the flange portion 39f and the second cylinder block 13.

An annular fixed body 31 is fixed to the rotary shaft 21 to be integrally rotational with the rotary shaft 21. The fixed body 31 is located rearward of the flange portion 21f and forward of the swash plate 23. A cylindrical movable body 32 having a closed end is located between the flange portion 21f and the fixed body 31. The movable body 32 is movable along the axis of the rotary shaft 21 with respect to the fixed body 31.

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 of the rotary shaft 21 from the peripheral edge of the bottom portion 32a. The inner circumferential surface of the cylindrical portion 32b is slidable along the outer circumferential surface of the fixed body 31. This allows the movable body 32 to rotate integrally with the rotary shaft 21 via the fixed body 31. The clearance between the inner circumferential surface of the cylindrical portion 32b and the outer circumferential surface of the fixed body 31 is sealed by a sealing member 33. The clearance between the insertion hole 32e and the rotary shaft 21 is sealed by a sealing member 34. The fixed body 31 and the movable body 32 define a control pressure chamber 35 in between.

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.

In the crank chamber 24, a lug arm 40 is provided between the swash plate 23 and the flange portion 39f. The lug arm 40 substantially has an L shape extending from a first end to a second end. The lug arm 40 has a weight portion 40a formed at one end. The weight portion 40a extends to a position in front of the swash plate 23 through a groove 23b of the swash plate 23.

The first end of the lug arm 40 is coupled to the upper side (upper side as viewed in FIG. 1) of the swash plate 23 by a first pin 41, which extends across the groove 23b. This structure allows the first end of the lug arm 40 to be supported by the swash plate 23 such that the first end of the lug arm 40 can pivot about a first pivot axis M1, which coincides with the axis of the first pin 41. The second end of the lug arm 40 is coupled to the supporting member 39 by a second pin 42. This structure allows the second end of the lug arm 40 to be supported by the supporting member 39 such that the second end of the lug arm 40 can pivot about a second pivot axis M2, which coincides with the axis of the second pin 42.

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 a movable body insertion hole 32h for receiving a third pin 43. The swash plate 23 has a swash plate insertion hole 23h for receiving the third pin 43 on the lower side (lower side as viewed in FIG. 1). The third pin 43 couples the coupling portion 32c to the lower part of the swash plate 23.

The second valve plate 17 has a restriction 36a, which communicates with the discharge chamber 15b. The second cylinder block 13 has a communication portion 36b in an end face that faces the second valve plate 17. The communication portion 36b connects the pressure adjusting chamber 15c and the restriction 36a to each other. The discharge chamber 15b and the control pressure chamber 35 are connected to each other via the restriction 36a, the communication portion 36b, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b. Therefore, the restriction 36a, the communication portion 36b, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b form a supply passage extending from the discharge chamber 15b to the control pressure chamber 35. The restriction 36a reduces the opening degree of the supply passage.

The pressure in the control pressure chamber 35 is regulated by introducing refrigerant gas from the discharge chamber 15b to the control pressure chamber 35 and discharging refrigerant gas from the control pressure chamber 35 to the suction chamber 15a. Thus, the refrigerant gas introduced into the control pressure chamber 35 serves as control gas for regulating 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 of the rotary shaft 21 with respect to the fixed body 31. An electromagnetic displacement control valve 50 for controlling the pressure in the control pressure chamber 35 is installed in the rear housing member 15. The displacement control valve 50 is electrically connected to a control computer 50c. Signaling connection is provided between the control computer 50c and an air conditioner switch 50s.

As shown in FIG. 2, a valve housing 50h of the displacement control valve 50 includes a cylindrical first housing member 51, which accommodates an electromagnetic solenoid 53, a cylindrical second housing member 52, which has a closed end and attached to the first housing member 51, and a lid member 52f, which closes an opening of the second housing member 52 that is located on the opposite side to the first housing member 51. The lid member 52f is press fitted in the opening of the second housing member 52.

The electromagnetic solenoid 53 has a fixed iron core 54 and a movable iron core 55, which is attracted to the fixed iron core 54 based on excitation by current supplied to a coil 53c. The fixed iron core 54 is arranged to be closer to the second housing member 52 than the movable iron core 55 is to the second housing member 52. The electromagnetic force of the electromagnetic solenoid 53 attracts the movable iron core 55 toward the fixed iron core 54. The electromagnetic solenoid 53 is subjected to current control (duty cycle control) performed by the control computer 50c. A spring 56 is located between the fixed iron core 54 and the movable iron core 55. The spring 56 urges the movable iron core 55 away from the fixed iron core 54.

A pillar-like drive force transmitting member 57 is attached to the movable iron core 55. The drive force transmitting member 57 is allowed to move integrally with the movable iron core 55. A back pressure chamber 58 is defined between a bottom wall 52e of the second housing member 52 and the fixed iron core 54. The drive force transmitting member 57 extends through the fixed iron core 54 and projects into the back pressure chamber 58. The fixed iron core 54 has a recess 54e, which is formed in an end face of the fixed iron core 54 that is close to the bottom wall 52e of the second housing member 52 and surrounds the drive force transmitting member 57. The recess 54e and the bottom wall 52e define the back pressure chamber 58.

An accommodating chamber 59 is formed in the second housing member 52. The accommodating chamber 59 accommodates a pressure sensing mechanism 60. The pressure sensing mechanism 60 is formed by a support 61, a bellows 62, a pressure receiving body 63, and a spring 64. The support 61 is capable of contacting and separating from an end face of the lid member 52f that faces the accommodating chamber 59. The bellows 62 can extend and contract and has an end coupled to the support 61. The pressure receiving body 63 is coupled to the other end of the bellows 62. The spring 64 is arranged in the bellows 62 to urges the support 61 and the pressure receiving body 63 away from each other.

The bellows 62 accommodates a stopper 61a, which is integrally formed with the support 61. The pressure receiving body 63 has a stopper 63a, which protrudes toward the stopper 61a of the support 61. The stopper 61a of the support 61 and the stopper 63a of the pressure receiving body 63 define the smallest length of the bellows 62.

A recess 52a, which is continuous with the accommodating chamber 59, is formed in the bottom wall 52e of the second housing member 52. Further, an annular valve seat member 65, which has a valve hole 65h, is arranged in the accommodating chamber 59 at a position close to the bottom wall 52e. The valve seat member 65 is formed separately from the second housing member 52. The end face of the valve seat member 65 that faces the recess 52a is flat and contacts a step 52b formed between the accommodating chamber 59 and the recess 52a with each other. The valve seat member 65 has an annular projection 65a formed on the inner end face, which faces the pressure sensing mechanism 60. The projection 65a projects toward the pressure sensing mechanism 60.

The accommodating chamber 59 accommodates an urging spring 66. The urging spring 66 is located between the valve seat member 65 and the lid member 52f. The end of the urging spring 66 that faces the lid member 52f is coupled to the lid member 52f, and the end of the urging spring 66 that faces the valve seat member 65 is coupled to a part of the valve seat member 65 that is outside the projection 65a. Since the projection 65a is located in the urging spring 66, the urging spring 66 is prevented from moving toward the projection 65a by the projection 65a. The valve seat member 65 is pressed against the step 52b by the urging spring 66 so that the position of the valve seat member 65 is determined.

A valve chamber 67 is defined between the valve seat member 65 and the recess 52a in the second housing member 52. The second housing member 52 accommodates a valve member 68, which extends through the bottom wall 52e of the second housing member 52. The valve member 68 also extends through the valve chamber 67 and the valve hole 65h from the back pressure chamber 58 to the accommodating chamber 59. The valve member 68 has a first valve body 68v, which is accommodated in the valve chamber 67. The valve member 68 has a pillar-like projection 68a on an end face that is located in the accommodating chamber 59. The projection 68a is coupled to the pressure receiving body 63. That is, the valve member 68 is integrated with the pressure sensing mechanism 60.

On the end face of the valve seat member 65 that faces the recess 52a, a valve seat 65e, on which the first valve body 68v is seated, is formed about the valve hole 65h. Therefore, the valve seat member 65 has the valve seat 65e, on which the first valve body 68v is seated. The first valve body 68v is capable of opening and closing the valve hole 65h by separating from and contacting the valve seat 65e. A cylindrical guide wall 69 is formed in the bottom wall 52e of the second housing member 52. The guide wall 69 guides the valve member 68 in the moving direction of the drive force transmitting member 57. The back pressure chamber 58 is located between the electromagnetic solenoid 53 and the valve chamber 67. The valve chamber 67 and the back pressure chamber 58 are connected to each other via a clearance 69s between the guide wall 69 and the valve member 68. A communication passage 75, which connects the valve chamber 67 and the back pressure chamber 58 to each other, is formed in the bottom wall 52e of the second housing member 52. The back pressure chamber 58 is connected to an accommodating chamber 55a, which accommodates the movable iron core 55, via a clearance between the drive force transmitting member 57 and the fixed iron core 54.

The accommodating chamber 59 communicates with the pressure adjusting chamber 15c through a passage 71. The valve chamber 67 communicates with the suction chamber 15a through a passage 72. Accordingly, the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, the passage 71, the accommodating chamber 59, the valve hole 65h, the valve chamber 67, and the passage 72 form a discharge passage extending from the control pressure chamber 35 to the suction chamber 15a.

The cross-sectional area of the valve hole 65h, which is selectively opened and closed by the first valve body 68v, is equal to the effective pressure receiving area of the bellows 62. Therefore, when the first valve body 68v is closed, the pressure sensing mechanism 60 is not influenced by the pressure in the accommodating chamber 59. The bellows 62 senses the pressure that is applied to the valve member 68 in the back pressure chamber 58, thereby either extending or contracting in the moving direction of the drive force transmitting member 57. Extension and contraction of the bellows 62 is used to position the first valve body 68v and contributes to the adjustment of the valve opening degree of the first valve body 68v. The opening degree of the first valve body 68v is determined by the balance of the electromagnetic force produced by the electromagnetic solenoid 53, the force of the spring 56, and the urging force of the pressure sensing mechanism 60.

The first valve body 68v adjusts the opening degree (passage cross-sectional area) of the discharge passage. When the first valve body 68v is seated on the valve seat 65e, the discharge passage is closed. In contrast, when the first valve body 68v separates from the valve seat 65e, the discharge passage is open.

A communicating chamber 73 is formed inside the lid member 52f. The communicating chamber 73 is located on the opposite side of the pressure sensing mechanism 60 to the valve chamber 67. The communicating chamber 73 is open on the side opposite to the accommodating chamber 59 and is connected to the suction chamber 15a via a passage 73a. The communicating chamber 73 accommodates a valve opening spring 73f, which urges the pressure sensing mechanism 60 and the valve member 68 toward the electromagnetic solenoid 53. The urging force of the valve opening spring 73f, which urges the pressure sensing mechanism 60 and the valve member 68 toward the electromagnetic solenoid 53, is set to be smaller than the urging force of the spring 64, which urges the support 61 and the pressure receiving body 63 away from each other.

When the pressure in the communicating chamber 73 exceeds a predetermined pressure (for example, 0.35 MPag), the pressure sensing mechanism 60 senses the pressure and contracts in the moving direction of the drive force transmitting member 57. Accordingly, the support 61 separates from the end face of the lid member 52f that faces the accommodating chamber 59, so that the support 61 opens the communicating chamber 73. When the support 61 contacts the end face of the lid member 52f that faces the accommodating chamber 59, the support 61 closes the communicating chamber 73. Therefore, the support 61 functions as a second valve body, which is located in the pressure sensing mechanism 60 and opens and closes the communicating chamber 73. The cross-sectional area of the communicating chamber 73, which selectively is opened and closed by the support 61, is equal to the effective pressure receiving area of the support 61. Therefore, when the first support 61 is closed, the pressure sensing mechanism 60 is not influenced by the pressure in the accommodating chamber 59.

A contraction allowance S1 of the pressure sensing mechanism 60 in the moving direction of the drive force transmitting member 57 (the distance between the stopper 61a of the support 61 and the stopper 63a of the pressure receiving body 63 when the valve opening degree of the first valve body 68v is maximized) is set to be smaller than a movable range R1 of the drive force transmitting member 57.

Operation of the present embodiment will now be described.

When the air conditioner switch 50s is turned on, current is supplied to the electromagnetic solenoid 53 of the variable displacement swash plate type compressor 10, which has the above described configuration. At this time, the electromagnetic force of the electromagnetic solenoid 53 attracts the movable iron core 55 toward the fixed iron core 54 against the force of the spring 56 as shown in FIG. 3. Then, the drive force transmitting member 57 pushes the valve member 68. Accordingly, the valve opening degree of the first valve body 68v is reduced. This reduces the flow rate of refrigerant gas that is discharged from the control pressure chamber 35 to the suction chamber 15a via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, the passage 71, the accommodating chamber 59, the valve hole 65h, the valve chamber 67, and the passage 72. Since refrigerant gas is introduced into the control pressure chamber 35 from the discharge chamber 15b via the restriction 36a, the communication portion 36b, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b, the pressure in the control pressure chamber 35 approaches the pressure in the discharge chamber 15b.

When the pressure difference between the control pressure chamber 35 and the crank chamber 24 is increased, the movable body 32 is moved such that the bottom portion 32a of the movable body 32 is separated away from the fixed body 31 as shown in FIG. 4. This causes the swash plate 23 to pivot about the first pivot axis M1. As the swash plate 23 pivots about the first pivot axis M1, the ends of the lug arm 40 pivot about the first pivot axis M1 and the second pivot axis M2, respectively, so that the lug arm 40 is separated away from the flange portion 39f of the supporting member 39. 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. The movable body 32 is configured to contact the flange portion 21f when the swash plate 23 reaches the maximum inclination angle. The contact between the movable body 32 and the flange portion 21f maintains the maximum inclination angle of the swash plate 23.

An increase in the valve opening degree of the first valve body 68v as shown in FIG. 2 increases the flow rate of refrigerant gas that is discharged from the control pressure chamber 35 to the suction chamber 15a via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, the passage 71, the accommodating chamber 59, the valve hole 65h, the valve chamber 67, and the passage 72, so that the pressure in the control pressure chamber 35 approaches the pressure in the suction chamber 15a.

When the pressure difference between the control pressure chamber 35 and the crank chamber 24 is decreased, the movable body 32 is moved such that the bottom portion 32a of the movable body 32 approaches the fixed body 31 as shown in FIG. 1. This causes the swash plate 23 to pivot about the first pivot axis M1 in a direction opposite to the pivoting direction for increasing the inclination angle of the swash plate 23. As the swash plate 23 pivots about the first pivot axis M1 in a direction opposite to the inclination angle increasing direction, the ends of the lug arm 40 pivot about the first pivot axis M1 and the second pivot axis M2, respectively, in a direction opposite to the pivoting direction for increasing the inclination angle of the swash plate 23, so that the lug arm 40 approaches the flange portion 39f of the supporting member 39. 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. The lug arm 40 is configured to contact the flange portion 39f of the supporting member 39 when the swash plate 23 reaches the minimum inclination angle. The contact between the lug arm 40 and the flange portion 39f maintains the minimum inclination angle of the swash plate 23.

When the air conditioner switch 50s is turned off, the current supply to the electromagnetic solenoid 53 is stopped. At this time, if the pressure in the suction chamber 15a is higher than a predetermined pressure, the pressure in the back pressure chamber 58, which is a suction pressure zone, is raised. Therefore, the pressure in the back pressure chamber 58 acts to move the first valve body 68v in a direction closing the discharge passage.

When the pressure in the suction chamber 15a is higher than the predetermined pressure, the pressure sensing mechanism 60 senses that the pressure in the communicating chamber 73 is higher than the predetermined pressure and contracts in the moving direction of the drive force transmitting member 57 as shown in FIG. 5. Accordingly, the support 61 separates from the end face of the lid member 52f that faces the accommodating chamber 59, so that the communicating chamber 73 is opened. Further, the valve opening spring 73f urges the pressure sensing mechanism 60 and the valve member 68 toward the electromagnetic solenoid 53. Accordingly, the support 61 is maintained separated from an end face of the lid member 52f that corresponds to the accommodating chamber 59. As a result, refrigerant gas from the control pressure chamber 35 is delivered to the suction chamber 15a via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, the passage 71, the accommodating chamber 59, the communicating chamber 73, and the passage 73a. This allows the pressure in the control pressure chamber 35 to be substantially equal to the pressure in the suction chamber 15a. Therefore, when no current is supplied to the electromagnetic solenoid 53, the swash plate 23 is moved to and maintained at the minimum inclination angle.

Further, since the valve opening spring 73f urges the pressure sensing mechanism 60 and the valve member 68 toward the electromagnetic solenoid 53, the first valve body 68v is maintained separated from the valve seat 65e. Accordingly, the refrigerant gas is discharged from the control pressure chamber 35 to the suction chamber 15a via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, the passage 71, the accommodating chamber 59, the valve hole 65h, the valve chamber 67, and the passage 72. That is, the discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a via the discharge passage and the discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a via the accommodating chamber 59 and the communicating chamber 73 are performed simultaneously. Therefore, compared to a case in which discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a is performed only via the accommodating chamber 59 and the communicating chamber 73, the flow rate of refrigerant gas that is discharged from the control pressure chamber 35 to the suction chamber 15a is increased, so that the inclination angle of the swash plate 23 is smoothly minimized.

Thereafter, when the air conditioner switch 50s is turned on and current supply to the electromagnetic solenoid 53 is resumed, the variable displacement swash plate type compressor 10 is operated at the minimum displacement. Thus, the load on the variable displacement swash plate type compressor 10 is prevented from being increased due to an abrupt increase in the displacement.

FIG. 6 illustrates a state in which the pressure sensing mechanism 60 senses that the pressure in the communicating chamber 73 exceeds the predetermined pressure, and the stopper 61a of the support 61 and the stopper 63a of the pressure receiving body 63 contact each other, so that the bellows 62 is contracted to the smallest length. Suppose that, in this state, the air conditioner switch 50s is turned on to supply current to the electromagnetic solenoid 53. In this case, the movable iron core 55 is attracted toward the fixed iron core 54 and the drive force transmitting member 57 pushes the valve member 68. This causes the first valve body 68v to be seated on the valve seat 65e to close the discharge passage.

At this time, since the pressure sensing mechanism 60 is contracted in the moving direction of the drive force transmitting member 57, a clearance H1 is formed between the support 61 and the end face of the lid member 52f that faces the accommodating chamber 59. Further, the contraction allowance S1 of the pressure sensing mechanism 60 in the moving direction of the drive force transmitting member 57 is set to be smaller than the movable range R1 of the drive force transmitting member 57. Therefore, between the movable iron core 55 and the fixed iron core 54, a clearance H2 remains that is greater than the clearance H1 between the support 61 and the end face of the lid member 52f that faces the accommodating chamber 59.

In a state in which the first valve body 68v is seated on the valve seat 65e as shown in FIG. 7, if the movable iron core 55 is further attracted to the fixed iron core 54, the drive force transmitting member 57 is actuated to push the pressure sensing mechanism 60 and the valve member 68 toward the communicating chamber 73. At this time, since the valve seat member 65 is formed separately from the valve housing 50h, the valve seat member 65 is moved toward the communicating chamber 73 with respect to the valve housing 50h. Accordingly, even if the bellows 62 is in the most contracted state with the stopper 61a of the support 61 and the stopper 63a of the pressure receiving body 63 contacting each other, the support 61 will be returned to a position where the support 61 contacts the end face of the lid member 52f that faces the accommodating chamber 59 and closes the communicating chamber 73.

Thus, the first valve body 68v and the support 61 close to stop discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a via the discharge passage and discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a via the accommodating chamber 59 and the communicating chamber 73.

Since refrigerant gas is introduced into the control pressure chamber 35 from the discharge chamber 15b via the restriction 36a, the communication portion 36b, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b, the pressure in the control pressure chamber 35 approaches the pressure in the discharge chamber 15b. Accordingly, the inclination angle of the swash plate 23 is increased.

When the pressure in the suction chamber 15a drops from the predetermined pressure, and the pressure sensing mechanism 60 is gradually extended from the contracted state in the moving direction of the drive force transmitting member 57, the first valve body 68v is moved toward the electromagnetic solenoid 53. At this time, since the valve seat member 65 is urged toward the first valve body 68v by the urging spring 66, the valve seat member 65 is moved toward the electromagnetic solenoid 53 while following the movement of the first valve body 68v toward the electromagnetic solenoid 53. Thus, the first valve body 68v is maintained seated on the valve seat 65e.

In a case in which the rotary shaft 21 receives rotational drive force from the engine E via the power transmission mechanism PT, which is a clutchless mechanism, the rotational drive force is constantly transmitted to the rotary shaft 21 from the engine E via the power transmission mechanism PT even if no current is supplied to the electromagnetic solenoid 53. Therefore, the power of the engine E is consumed slightly. Therefore, to minimize consumption of the power of the engine E, minimum displacement operation, in which the swash plate 23 is maintained at the minimum inclination angle, is preferable in a state in which no current is supplied to the electromagnetic solenoid 53.

Therefore, when no current is supplied to the electromagnetic solenoid 53, the opening degree of the first valve body 68v is maximized so that refrigerant gas is discharged from the control pressure chamber 35 to the suction chamber 15a via the discharge passage. Accordingly, the displacement control valve 50 substantially equalizes the pressure in the control pressure chamber 35 with the pressure in the suction chamber 15a and minimizes the inclination angle of the swash plate 23. However, if the pressure in the suction chamber 15a exceeds the predetermined pressure when no current is supplied to the electromagnetic solenoid 53, the pressure in the back pressure chamber 58 is increased. In this case, the pressure in the back pressure chamber 58 causes the first value body 68v to close the discharge passage, which is undesirable.

In this respect, according to the present embodiment, the pressure sensing mechanism 60 is contracted in the moving direction of the drive force transmitting member 57 when the pressure in the communicating chamber 73 is higher than the predetermined pressure. Accordingly, the support 61 separates from the end face of the lid member 52f that faces the accommodating chamber 59, so that the support 61 opens the communicating chamber 73. As a result, refrigerant gas from the control pressure chamber 35 is delivered to the suction chamber 15a via the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure adjusting chamber 15c, the passage 71, the accommodating chamber 59, the communicating chamber 73, and the passage 73a.

This allows the pressure in the control pressure chamber 35 to be substantially equal to the pressure in the suction chamber 15a when the current supply to the electromagnetic solenoid 53 is stopped. Therefore, the inclination angle of the swash plate 23 is minimized. Thus, in a state in which no current is supplied to the electromagnetic solenoid 53 in a configuration in which the rotary shaft 21 receives rotational drive force from the engine E via the power transmission mechanism PT, which is a clutchless mechanism, the inclination angle of the swash plate 23 is changed to and maintained at the minimum inclination even if the pressure in the suction chamber 15a changes. This ensures the minimum displacement operation. As a result, the power consumption of the engine E is minimized.

The above described embodiment provides the following advantages.

(1) The displacement control valve 50 has the communicating chamber 73, which is located on the opposite side of the pressure sensing mechanism 60 to the valve chamber 67 and communicates with the suction chamber 15a, and the support 61, which is located in the pressure sensing mechanism 60 and opens and closes the communicating chamber 73. When the current supply to the electromagnetic solenoid 53 is stopped and the pressure in the communicating chamber 73 is higher than the predetermined pressure, the pressure sensing mechanism 60 is contracted in the moving direction of the drive force transmitting member 57, so that the support 61 opens. If the pressure in the suction chamber 15a exceeds the predetermined pressure when no current is supplied to the electromagnetic solenoid 53, the pressure in the suction chamber 15a acts to move the first valve body 68v in a direction closing the discharge passage.

With this being the situation, the pressure sensing mechanism 60 is contracted in the moving direction of the drive force transmitting member 57 when the pressure in the communicating chamber 73 is higher than the predetermined pressure so that the support 61 opens. This allows the refrigerant gas in the control pressure chamber 35 to be discharged to the suction chamber 15a via the accommodating chamber 59 and the communicating chamber 73. As a result, the pressure in the control pressure chamber 35 is substantially equalized with the pressure in the suction chamber 15a. Therefore, even if the pressure in the suction chamber 15a changes when no current is supplied to the electromagnetic solenoid 53, the inclination angle of the swash plate 23 is changed to and maintained at the minimum inclination angle.

(2) The communicating chamber 73 accommodates a valve opening spring 73f, which urges the pressure sensing mechanism 60 and the valve member 68 toward the electromagnetic solenoid 53. Therefore, even if the pressure in the suction chamber 15a is increased when no current is supplied to the electromagnetic solenoid 53, and the pressure in the suction chamber 15a acts to move the first valve body 68v in the direction closing the discharge passage, the valve opening spring 73f urges the pressure sensing mechanism 60 and the valve member 68 toward the electromagnetic solenoid 53.

The discharge passage is thus prevented from being closed by the first valve body 68v. Thus, the discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a via the discharge passage and the discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a via the accommodating chamber 59 and the communicating chamber 73 can be performed simultaneously. Therefore, compared to a case in which discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a is performed only via the accommodating chamber 59 and the communicating chamber 73, the flow rate of refrigerant gas that is discharged from the control pressure chamber 35 to the suction chamber 15a can be increased, so that the inclination angle of the swash plate 23 can be smoothly minimized.

(3) The valve seat 65e, on which the first valve body 68v is seated, is formed on the valve seat member 65, and the valve seat member 65 is formed separately from the valve housing 50h. In this configuration, when the first valve body 68v is seated on the valve seat 65e, the drive force transmitting member 57 is actuated to move the pressure sensing mechanism 60 and the valve member 68 toward the communicating chamber 73. Therefore, even if the pressure sensing mechanism 60 is in a contracted state in the moving direction of the drive force transmitting member 57, the support 61 is returned to the position to close the communicating chamber 73.

(4) The accommodating chamber 59 accommodates the urging spring 66, which urges the valve seat member 65 toward the first valve body 68v. When the pressure in the suction chamber 15a drops from the predetermined pressure, and the pressure sensing mechanism 60 is gradually extended from the contracted state in the moving direction of the drive force transmitting member 57, the first valve body 68v is moved toward the electromagnetic solenoid 53. At this time, since the valve seat member 65 is urged toward the first valve body 68v by the urging spring 66, the valve seat member 65 can be moved toward the electromagnetic solenoid 53 while following the movement of the first valve body 68v toward the electromagnetic solenoid 53. Thus, the first valve body 68v can be maintained seated on the valve seat 65e.

(5) The communicating chamber 73 is open on the side opposite to the accommodating chamber 59 and communicates with the suction chamber 15a. This simplifies the structure of the displacement control valve 50 compared to a case in which, for example, the communicating chamber 73 and the back pressure chamber 58 are connected by a communication passage so that communicating chamber 73 and the back pressure chamber 58 are connected to each other.

(6) The contraction allowance S1 of the pressure sensing mechanism 60 in the moving direction of the drive force transmitting member 57 is set to be smaller than the movable range R1 of the drive force transmitting member 57. In this configuration, when the current supply to the electromagnetic solenoid 53 is performed, the first valve body 68v and the support 61 are reliably closed.

(7) According to the present embodiment, the inclination angle of the swash plate 23 can be minimized when the current supply to the electromagnetic solenoid 53 is stopped. Therefore, when the current supply to the electromagnetic solenoid 53 is resumed, the variable displacement swash plate type compressor 10 is operated at the minimum displacement. Thus, the load on the variable displacement swash plate type compressor 10 is prevented from being increased due to an abrupt increase in the displacement.

(8) The variable displacement swash plate type compressor 10 of the present embodiment receives rotational drive force from the engine E via the power transmission mechanism PT, which is a clutchless mechanism. This configuration reduces the weight of the entire variable displacement swash plate type compressor 10 and the electricity consumption for driving the power transmission mechanism, which is an electromagnetic clutch mechanism, compared to a case in which the rotary shaft 21 receives rotational drive force from the engine E via a power transmission mechanism that is an electromagnetic clutch mechanism only when current is supplied to the electromagnetic solenoid 53.

(9) According to the present embodiment, in a state in which no current is supplied to the electromagnetic solenoid 53 in a configuration in which the rotary shaft 21 receives rotational drive force from the engine E via the power transmission mechanism PT, which is a clutchless mechanism, the inclination angle of the swash plate 23 is changed to and maintained at the minimum inclination even if the pressure in the suction chamber 15a is higher than the predetermined pressure. This reliably allows the operation at the minimum displacement. As a result, the power consumption of the engine E is minimized.

(10) The displacement control valve 50 has the guide wall 69, which guides the valve member 68 in the moving direction of the drive force transmitting member 57. The valve chamber 67 and the back pressure chamber 58 are connected to each other via the clearance 69s between the guide wall 69 and the valve member 68. Since the valve member 68 is guided by the guide wall 69, the valve member 68 is prevented from being tilted with respect to the moving direction, so that the first valve body 68v is guided to a reliable closed state. Since the clearance 69s is formed between the guide wall 69 and the valve member 68, the valve member 68 moves smoothly. This allows the first valve body 68v to move smoothly. The responsiveness of the displacement control valve 50 is improved accordingly.

(11) The valve chamber 67 and the back pressure chamber 58 are connected to each other by the communication passage 75. This configuration shortens the time for the pressure in the back pressure chamber 58 to be equalized with the pressure in the suction chamber 15a, which is equal to the valve chamber 67, compared to a case in which, for example, the valve chamber 67 and the back pressure chamber 58 are connected to each other only by the clearance 69s between the guide wall 69 and the valve member 68 without providing the communication passage 75.

(12) The urging spring 66 for urging the valve seat member 65 toward the first valve body 68v is located between the valve seat member 65 and the lid member 52f. In this configuration, before the lid member 52f, the pressure sensing mechanism 60, the valve seat member 65, and the valve member 68 are installed in the valve housing 50h, the urging spring 66 urges the valve seat member 65 toward the first valve body 68v. Therefore, the lid member 52f, the pressure sensing mechanism 60, the valve seat member 65, and the valve member 68 are assembled as a unit via the urging spring 66. Compared to a case in which the lid member 52f, the pressure sensing mechanism 60, the valve seat member 65, and the valve member 68 are independent, the unit can be easily installed in the valve housing 50h.

Since the urging spring 66 is located between the valve seat member 65 and the lid member 52f, the positions of the valve seat member 65 and the pressure sensing mechanism 60 can be adjusted by using the urging spring 66 during assembly. This allows the positions of the valve seat member 65 and the pressure sensing mechanism 60 to be easily determined.

The above described embodiment may be modified as follows.

As shown in FIG. 8, the displacement control valve 50 may have a communication passage 77, which connects the communicating chamber 73 and the back pressure chamber 58 to each other. Further, the communicating chamber 73 may be connected to the suction chamber 15a by connecting the communicating chamber 73 and the back pressure chamber 58 to each other by the communication passage 77. The communication passage 77 is formed by an annular groove 77a, which is formed on the outer surface of the lid member 52f, a through hole 77b, which is formed in the lid member 52f to connect the annular groove 77a with the communicating chamber 73, and a communication passage 77c, which is formed in the second housing member 52 to connect the annular groove 77a with the back pressure chamber 58.

As shown in FIG. 9, the back pressure chamber 58 may be omitted, and the drive force transmitting member 57 may be integrated with the valve member 68.

In the illustrated embodiment, the urging spring 66 may be omitted. In this case, at the assembly of the valve housing 50h, refrigerant gas is introduced from the control pressure chamber 35 to the accommodating chamber 59 with the pressure sensing mechanism 60, the valve seat member 65, and the valve member 68 arranged in the valve housing 50h, so that the valve seat member 65 is pressed against the step 52b by the pressure of the refrigerant gas introduced into the accommodating chamber 59. The valve seat member 65 is positioned by pressing the valve seat member 65 against the step 52b by the pressure of the refrigerant gas.

In the illustrated embodiment, a valve seat on which the first valve body 68v is seated may be formed integrally with the valve housing 50h.

In the illustrated embodiment, the valve opening spring 73f may be omitted.

In the illustrated embodiment, for example, the back pressure chamber 58 may be defined by the fixed iron core 54 and a recess that is formed in the bottom wall 52e of the second housing member 52 that faces the fixed iron core 54 and surrounds the drive force transmitting member 57.

In the illustrated embodiment, the valve chamber 67 may be connected to the suction chamber 14a via the passage 72 as long as a discharge passage is formed from the control pressure chamber 35 to the suction pressure zone.

In the illustrated embodiment, the discharge chamber 14b and the control pressure chamber 35 may be connected to each other via the restriction 36a, the communication portion 36b, the pressure adjusting chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b.

In the illustrated embodiment, the cross-sectional area of the valve hole 65h and the effective pressure receiving area of the bellows 62 do not necessarily need to be exactly the same as long as these areas are substantially equal to each other.

In the illustrated embodiment, the cross-sectional area of the communicating chamber 73 and the effective pressure receiving area of the support 61 do not necessarily need to be exactly the same as long as these areas are substantially equal to each other.

In the illustrated embodiment, drive power may be obtained from an external drive source via a clutch.

In the illustrated embodiment, the variable displacement swash plate type compressor 10 is a double-headed piston swash plate type compressor having the double-headed pistons 25, but may be a single-headed piston swash plate type compressor having single-headed pistons.

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.

Claims

1. A variable displacement swash plate type compressor comprising:

a housing having a crank chamber;

a swash plate accommodated in the crank chamber, wherein the swash plate receives a drive force from a rotary shaft to rotate and is capable of changing its inclination angle relative to the rotary shaft;

a piston engaged with the swash plate;

a movable body, which is coupled to the swash plate and changes the inclination angle of the swash plate;

a control pressure chamber defined in the housing by the movable body, wherein pressure in the control pressure chamber is changed by introducing control gas therein so that the movable body is moved in the axial direction of the rotary shaft; and

a displacement control valve that controls the pressure in the control pressure chamber, wherein

the piston is reciprocated by a stroke that corresponds to the inclination angle of the swash plate,

the displacement control valve includes: a drive force transmitting member, which is driven by an electromagnetic solenoid; a valve member having a first valve body, wherein the first valve body adjusts an opening degree of discharge passage that extends from the control pressure chamber to a suction pressure zone; a valve chamber, which accommodates the first valve body and communicates with the suction pressure zone; an accommodating chamber, which communicates with the control pressure chamber; a pressure sensing mechanism, which is accommodated in the accommodating chamber and integrated with the valve member, wherein, by sensing a pressure in the suction pressure zone that acts on the valve member, the pressure sensing mechanism extends or contracts in the moving direction of the drive force transmitting member, thereby adjusting the valve opening degree of the first valve body; a communicating chamber, which is located on the opposite side of the pressure sensing mechanism from the valve chamber and communicates with the suction pressure zone; and a second valve body, which is located in the pressure sensing mechanism and selectively opens and closes the communicating chamber, and

when a current supply to the electromagnetic solenoid is stopped and the pressure in the suction pressure zone in the communicating chamber is higher than a predetermined pressure, the pressure sensing mechanism contracts in the moving direction of the drive force transmitting member, thereby opening the second valve body.

2. The variable displacement swash plate type compressor according to claim 1, further comprising a valve opening spring, which is provided in the communicating chamber and urges the pressure sensing mechanism and the valve member toward the electromagnetic solenoid.

3. The variable displacement swash plate type compressor according to claim 1, wherein the displacement control valve further includes:

a valve housing; and

a valve seat member, which is formed separately from the valve housing, wherein the valve seat member has a valve seat, on which the first valve body is seated.

4. The variable displacement swash plate type compressor according to claim 3, further comprising an urging spring, which is provided in the accommodating chamber and urges the valve seat member toward the first valve body.

5. The variable displacement swash plate type compressor according to claim 1, wherein the communicating chamber is open on the side opposite to the accommodating chamber and communicates with the suction pressure zone.

6. The variable displacement swash plate type compressor according to claim 1, wherein a contraction allowance of the pressure sensing mechanism in the moving direction of the drive force transmitting member is set to be smaller than a movable range of the drive force transmitting member.

7. The variable displacement swash plate type compressor according to claim 1, wherein the piston is a double-headed piston.

8. The variable displacement swash plate type compressor according to claim 1, wherein the rotary shaft receives drive force from an external drive source via the power transmission mechanism, which is a clutchless mechanism.