VARIABLE DISPLACEMENT SWASH PLATE COMPRESSOR

BACKGROUND OF THE INVENTION

The present invention relates to a variable displacement swash plate compressor.

Japanese Laid-Out Patent Publication No. 5-172052 describes a conventional variable displacement swash plate compressor (hereafter simply referred to as the compressor). The compressor has a housing including a front housing member, a cylinder block, and a rear housing member. The front housing member and the rear housing member each includes a suction chamber and a discharge chamber. The cylinder block includes a swash plate chamber and cylinder bores. A rotatable drive shaft is supported in the housing. A swash plate that is rotatable together with the drive shaft is arranged in the swash plate chamber. A link mechanism is located between the drive shaft and the swash plate to allow the inclination angle of the swash plate to change. The inclination angle refers to an angle of the swash plate relative to a plane orthogonal to the rotation axis of the drive shaft. Each cylinder bore accommodates a reciprocal piston. Two shoes are provided for each piston to serve as a conversion mechanism that uses the rotation of the swash plate to reciprocate the piston in the corresponding cylinder bore with a stroke that is in accordance with the inclination angle of the swash plate. An actuator, which includes a movable body and a control pressure chamber, changes the inclination angle of the swash plate. A control mechanism regulates the pressure of the control pressure chamber to control the actuator.

The link mechanism includes a lug arm, first and second arms, and a movable body. The lug arm is fixed to the drive shaft and located in front of the swash plate chamber. The first arm is located on the front surface of the swash plate, and the second arm is located on the rear surface of the swash plate. The first arm pivotally couples the lug arm and the swash plate. The second arm pivotally couples the movable body and the swash plate.

In the compressor, the control mechanism increases the pressure of the control pressure chamber with the pressure of the refrigerant in the discharge chamber to move the movable body toward the swash plate along the axis of the drive shaft. As a result, the movable body pushes the swash plate and increases the inclination angle of the swash plate. The swash plate comes into contact with the lug arm when the inclination angle of the swash plate becomes maximal. This allows the compressor displacement to be maximized for each rotation of the drive shaft.

In the conventional compressor described above, contact of the swash plate and the lug arm restricts the swash plate at the maximum inclination angle. The lug arm is fixed to the drive shaft. Thus, contact of the swash plate and the lug arm may produce an impact that generates vibration and lowers the durability of the compressor. Further, contact of the swash plate and the lug arm produces noise. Such situations become further noticeable when quickly increasing the compressor displacement to the maximum amount.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a durable compressor with noise reduced.

One aspect of the present invention is a variable displacement swash plate compressor provided with a housing including a suction chamber, a discharge chamber, a swash plate chamber, and a cylinder bore. A drive shaft is rotationally supported by the housing. A swash plate is rotatable together with the drive shaft in the swash plate chamber. A link mechanism is arranged between the drive shaft and the swash plate. The link mechanism includes a supporting portion that pivotally supports the swash plate, and the link mechanism allows for changes in an inclination angle of the swash plate relative to a plane orthogonal to an axis of the drive shaft. A piston is reciprocally accommodated in the cylinder bore. A conversion mechanism is configured to reciprocate the piston in the cylinder bore with a stroke that is in accordance with the inclination angle of the swash plate when the swash plate rotates. An actuator is located in the swash plate chamber. The actuator is capable of changing the inclination angle of the swash plate. A control mechanism is configured to control the actuator. The actuator includes a partitioning body arranged on the drive shaft. The partitioning body is movable along the axis of the drive shaft. A movable body is arranged on the drive shaft. The movable body includes a coupling portion coupled to the swash plate, and the movable body moves in contact with the partitioning body along the axis of the drive shaft to change the inclination angle of the swash plate. A control pressure chamber is defined by the partitioning body and the movable body. The movable body is moved by drawing refrigerant in the control pressure chamber from the discharge chamber. The swash plate is configured to contact and move the partitioning body as the inclination angle increases.

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 view showing a compressor of a first embodiment when the displacement is maximal;

FIG. 2 is a schematic diagram showing a control mechanism in the compressor of FIG. 1;

FIG. 3A is a front view of a swash plate in the compressor of FIG. 1;

FIG. 3B is a cross-sectional view of the swash plate in the compressor of FIG. 1;

FIG. 4 is a cross-sectional view showing the compressor of FIG. 1 when the displacement is minimal;

FIG. 5 is a partially enlarged cross-sectional view showing an abutment portion pushing a partitioning body in the compressor of FIG. 1;

FIG. 6 is a partially enlarged cross-sectional view showing a compressor of a second embodiment when the inclination angle of the swash plate is minimal;

FIG. 7A is a front view of the swash plate in the compressor of FIG. 6;

FIG. 7B is a cross-sectional view of the swash plate in the compressor of FIG. 6;

FIG. 8 is a partially enlarged cross-sectional view showing the swash plate at a predetermined second inclination angle in the compressor of FIG. 6;

FIG. 9 is a partially enlarged cross-sectional view showing the compressor of FIG. 6 when the inclination angle of the swash plate is maximal; and

FIG. 10 is a graph showing the relationship of the swash plate inclination angle and the variable pressure difference.

DETAILED DESCRIPTION OF THE EMBODIMENTS

First and second embodiments of the present invention will now be described with reference to the drawings. Each compressor of the first and second embodiments is a variable displacement compressor that employs double-headed pistons and a swash plate. The compressor is installed in a vehicle to form a refrigeration circuit of a vehicle air conditioner.

First Embodiment

Referring to FIGS. 1, a compressor of the first embodiment includes a housing 1, a drive shaft 3, a swash plate 5, a link mechanism 7, pistons 9, front and rear shoes 11a and 11b, an actuator 13, and a control mechanism 15, which is shown in FIG. 2. Each piston 9 is provided with a pair of the shoes 11a and 11b.

As shown in FIG. 1, the housing 1 includes a front housing member 17, which is located at the front of the compressor, a rear housing member 19, which is located at the rear of the compressor, first and second cylinder blocks 21 and 23, which are located between the front housing member 17 and the rear housing member 19, and first and second valve formation plates 39 and 41.

The front housing member 17 includes a boss 17a, which projects toward the front. A sealing device 25 is arranged in the boss 17a. Further, the front housing member 17 includes a first suction chamber 27a and a first discharge chamber 29a. The first suction chamber 27a is located in a radially inner portion of the front housing member 17, and the first discharge chamber 29a is annular and is located in a radially outer portion of the front housing member 17.

The front housing member 17 includes a first front communication passage 18a. The first front communication passage 18a includes a front end that is in communication with the first discharge chamber 29a and a rear end that opens at the rear end of the front housing member 17.

The rear housing member 19 includes the control mechanism 15 shown in FIG. 2. The rear housing member 19 includes a second suction chamber 27b, a second discharge chamber 29b, and a pressure regulation chamber 31. The pressure regulation chamber 31 is located in a radially central portion of the rear housing member 19. The second suction chamber 27b is annular and located at a radially outer side of the pressure regulation chamber 31 in the rear housing member 19. The second discharge chamber 29b is also annular and located at a radially outer side of the second suction chamber 27b in the rear housing member 19.

The rear housing member 19 includes a first rear communication passage 20a. The first rear communication passage 20a includes a rear end that is in communication with the second discharge chamber 29b and a front end that opens at the front end of the rear housing member 19.

A swash plate chamber 33 is defined in the first cylinder block 21 and the second cylinder block 23. The swash plate chamber 33 is located in an axially middle portion of the housing 1.

The first cylinder block 21 includes first cylinder bores 21a, which are arranged at equal angular intervals in the circumferential direction and which extend parallel to one another. Further, the first cylinder block 21 includes a first shaft bore 21b. The drive shaft 3 extends through the first shaft bore 21b. A first plain bearing 22a is arranged in the first shaft bore 21b.

The first cylinder block 21 also includes a first recess 21c, which is in communication and coaxial with the first shaft bore 21b. The first recess 21c is in communication with the swash plate chamber 33 and forms a portion of the swash plate chamber 33. A first thrust bearing 35a is arranged in a front portion of the first recess 21c. Further, the first cylinder block 21 includes a first communication passage 37a that communicates the swash plate chamber 33 with the first suction chamber 27a. The first cylinder block 21 also includes a first retainer groove 21e, which restricts the maximum open degree of first suction reed valves 391a, which will be described later.

The first cylinder block 21 includes a second front communication passage 18b. The second front communication passage 18b includes a front end that opens at the front end of the first cylinder block 21 and a rear end that opens at the rear end of the first cylinder block 21.

In the same manner as the first cylinder block 21, the second cylinder block 23 includes second cylinder bores 23a. Each second cylinder bore 23a is paired and axially aligned with one of the first cylinder bores 21a. The first cylinder bores 21a and the second cylinder bores 23a have the same diameter.

The second cylinder block 23 includes a second shaft bore 23b. The drive shaft 3 extends through the second shaft bore 23b. The second shaft bore 23b includes a second plain bearing 22b. The first and second plain bearings 22a and 22b may be replaced by ball bearings.

The second cylinder block 23 also includes a second recess 23c, which is in communication and coaxial with the second shaft bore 23b. Further, the second recess 23c is also in communication with the swash plate chamber 33 and forms a portion of the swash plate chamber 33. A second thrust bearing 35b is arranged in a rear portion of the second recess 23c. The second cylinder block 23 includes a second communication passage 37b that communicates the swash plate chamber 33 with the second suction chamber 27b. The second cylinder block 23 also includes a second retainer groove 23e, which restricts the maximum open degree of first suction reed valves 411a, which will be described later.

The second cylinder block 23 includes a discharge port 230, a converging discharge chamber 231, a third front communication passage 18c, a second rear communication passage 20b, and a suction port 330. The discharge port 230 is in communication with the converging discharge chamber 231. The discharge port 230 connects the converging discharge chamber 231 to a condenser (not shown), which is included in the refrigeration circuit. The suction port 330 connects the swash plate chamber 33 to an evaporator (not shown), which is included in the refrigeration circuit.

The third front communication passage 18c includes a front end that opens at a front end of the second cylinder block 23 and a rear end that is in communication with the converging discharge chamber 231. When the first cylinder block 21 is joined with the second cylinder block 23, the third front communication passage 18c is connected to the rear end of the second front communication passage 18b.

The second rear communication passage 20b includes a front end that is in communication with the converging discharge chamber 231 and a rear end that opens at the rear end of the second cylinder block 23.

The first valve formation plate 39 is arranged between the front housing member 17 and the first cylinder block 21. The second valve formation plate 41 is arranged between the rear housing member 19 and the second cylinder block 23.

The first valve formation plate 39 includes a first valve plate 390, a first suction valve plate 391, a first discharge valve plate 392, and a first retainer plate 393. First suction holes 390a extend through the first valve plate 390, the first discharge valve plate 392, and the first retainer plate 393. The number of the first suction holes 390a is the same as the number of the first cylinder bores 21a. First discharge holes 390b extend through the first valve plate 390 and the first suction valve plate 391. The number of the first discharge holes 390b is the same as the number of the first cylinder bores 21a. A first suction communication hole 390c extends through the first valve plate 390, the first suction valve plate 391, the first discharge valve plate 392, and the first retainer plate 393. A first discharge communication hole 390d extends through the first valve plate 390 and the first suction valve plate 391.

Each first cylinder bore 21a is in communication with the first suction chamber 27a through the corresponding first suction hole 390a. Further, each first cylinder bore 21a is in communication with the first discharge chamber 29a through the corresponding first discharge hole 390b. The first suction chamber 27a is in communication with the first communication passage 37a through the first suction communication hole 390c. The first front communication passage 18a is in communication with the second front communication passage 18b through the first discharge communication hole 390d.

The first suction valve plate 391 is arranged on the rear surface of the first valve plate 390. The first suction valve plate 391 includes first suction reed valves 391a, which may be elastically deformed to open and close the corresponding first suction holes 390a. The first discharge valve plate 392 is arranged on the front surface of the first valve plate 390. The first discharge valve plate 392 includes first discharge reed valves 392a, which may be elastically deformed to open and close the corresponding first discharge holes 390b. The first retainer plate 393 is arranged on the front surface of the first discharge valve plate 392. The first retainer plate 393 restricts the maximum open degree of each first discharge reed valve 392a.

The second valve formation plate 41 includes a second valve plate 410, a second suction valve plate 411, a second discharge valve plate 412, and a second retainer plate 413. Second suction holes 410a extend through the second valve plate 410, the second discharge valve plate 412, and the second retainer plate 413. The number of the second suction holes 410a is the same as the number of the second cylinder bores 23a. Second discharge holes 410b extend through the second valve plate 410 and the second suction valve plate 411. The number of the second discharge holes 410b is the same as the number of the second cylinder bores 23a. A second suction communication hole 410c extends through the second valve plate 410, the second suction valve plate 411, the second discharge valve plate 412, and the second retainer plate 413. A second discharge communication hole 410d extends through the second valve plate 410 and the second suction valve plate 411.

Each second cylinder bore 23a is in communication with the second suction chamber 27b through the corresponding second suction hole 410a. Further, each second cylinder bore 23a is in communication with the second discharge chamber 29b through the corresponding second discharge hole 410b. The second suction chamber 27b is in communication with the second communication passage 37b through the second suction communication hole 410c. The first rear communication passage 20a is in communication with the second rear communication passage 20b through the second discharge communication hole 410d.

The second suction valve plate 411 is arranged on the front surface of the second valve plate 410. The second suction valve plate 411 includes the second suction reed valves 411a, which may be elastically deformed to open and close the corresponding second suction holes 410a. The second discharge valve plate 412 is arranged on the rear surface of the second valve plate 410. The second discharge valve plate 412 includes second discharge reed valves 412a, which may be elastically deformed to open and close the corresponding second discharge holes 410b. The second retainer plate 413 is arranged on the rear surface of the second discharge valve plate 412. The second retainer plate 413 restricts the maximum open degree of each second discharge reed valve 412a.

In the compressor, the first front communication passage 18a, the first discharge communication hole 390d, the second front communication passage 18b, and the third front communication passage 18c form a first discharge communication passage 18. Further, the first rear communication passage 20a, the second discharge communication hole 410d, and the second rear communication passage 20b form a second discharge communication passage 20.

In the compressor, the first and second suction chambers 27a and 27b are in communication with the swash plate chamber 33 through the first and second communication passages 37a and 37b and the first and second suction communication holes 390c and 410c. Thus, the pressure of the first and second suction chambers 27a and 27b is substantially equal to the pressure of the swash plate chamber 33. Low-pressure refrigerant gas from the evaporator flows into the swash plate chamber 33 through the suction port 330. Thus, the pressure of the swash plate chamber 33 and the first and second suction chambers 27a and 27b is lower than the pressure of the first and second discharge chambers 29a and 29b.

The drive shaft 3 includes a shaft body 30, a first support member 43a, and a second support member 43b. The shaft body 30 includes a front portion defining a first small diameter portion 30a and a rear portion defining a second small diameter portion 30b. The shaft body 30, which extends from the front to the rear of the housing 1, extends through the sealing device 25 and the first and second plain bearings 22a and 22b. Thus, the shaft body 30 and, consequently, the drive shaft 3 are supported by the housing 1 rotationally about the axis O of the drive shaft 3. The shaft body 30 has a front end located in the boss 17a and a rear end projecting into the pressure regulation chamber 31.

The swash plate 5, the link mechanism 7, and an actuator 13 are arranged on the shaft body 30. The swash plate 5, the link mechanism 7, and the actuator 13 are each located in the swash plate chamber 33.

The first support member 43a is fitted to the first small diameter portion 30a of the shaft body 30. Further, the first support member 43a is located between the first small diameter portion 30a and the first plain bearing 22a in the first shaft bore 21b. The first support member 43a includes a flange 430, which contacts the first thrust bearing 35a, and a coupling portion (not shown), through which a second pin 47b is inserted. The front end of a recovery spring 44a is fitted to the first support member 43a. The recovery spring 44a extends from the flange 430 toward the swash plate 5 along the axis O of the drive shaft 3.

The second support member 43b is fitted to the rear of the second small diameter portion 30b of the shaft body 30 and located in the second shaft bore 23b. The front portion of the second support member 43b includes a flange 431, which contacts the second thrust bearing 35b. O-rings 51a and 51b are arranged on the second support member 43b at the rear side of the flange 431.

Referring to FIG. 1, the swash plate 5 is an annular plate and includes a front surface 5a and a rear surface 5b. The front surface 5a faces the front side of the compressor in the swash plate chamber 33. The rear surface 5b faces the rear side of the compressor in the swash plate chamber 33.

The swash plate 5 includes a ring plate 45. The ring plate 45 is an annular plate. An insertion hole 45a extends through the center of the ring plate 45. The shaft body 30 is inserted through the insertion hole 45a in the swash plate chamber 33 to couple the swash plate 5 to the drive shaft 3.

Referring to FIG. 3A, the surface of the ring plate 45 located at the same side as the rear surface 5b of the swash plate 5 includes two abutment portions 53a and 53b. The abutment portions 53a and 53b are separated from the center C of the swash plate 5 toward the lower end U of the swash plate 5. Further, the abutment portions 53a and 53b are arranged symmetrically relative to the center line L that extends through the center C of the swash plate 5.

The abutment portions 53a and 53b are identically shaped, triangular in cross-section, and project toward the rear from the ring plate 45 as shown in FIG. 3B. Referring to FIG. 1, when the swash plate 5 is inclined at a first predetermined inclination angle, the abutment portions 53a and 53b contact a partitioning body 13b, which will be described later. The abutment portions 53a and 53b may be designed to have any suitable shape.

The ring plate 45 includes a coupler (not shown) coupled to pulling arms 132, which will be described later.

As shown in FIG. 1, the link mechanism 7 includes a lug arm 49. The lug arm 49 is arranged at the front side of the swash plate 5 in the swash plate chamber 33 and located between the swash plate 5 and the first support member 43a. The lug arm 49 is generally L-shaped. The rear end of the lug arm 49 includes a weight 49a. The weight 49a extends over one half of the circumference of the actuator 13. The weight 49a may be designed to have a suitable shape.

A first pin 47a couples the rear end of the lug arm 49 to an upper portion of the ring plate 45. The first pin 47a corresponds to a supporting portion of the present invention. Thus, the lug arm 49 is supported by the ring plate 45, or the swash plate 5, so that the lug arm 49 is pivotal about the axis of the first pin 47a, namely, a first pivot axis M1. The first pivot axis M1 extends in a direction perpendicular to the axis O of the drive shaft 3. The drive shaft 3 is located between abutment portions 53a and 53b and the first pin 47a, or the first pivot axis M1.

A second pin 47b couples the front end of the lug arm 49 to the first support member 43a. Thus, the lug arm 49 is supported by the support member 43a, or the drive shaft 3, so that the lug arm 49 is pivotal about the axis of the second pin 47b, namely, a second pivot axis M2. The second pivot axis M2 extends parallel to the first pivot axis M1. The lug arm 49 and the first and second pins 47a and 47b are elements forming the link mechanism 7 of the present invention.

The weight 49a extends toward the rear of the lug arm 49, that is, the side opposite to the second pivot axis M2 as viewed from the first pivot axis M1. The lug arm 49 is supported by the first pin 47a on the ring plate 45 so that the weight 49a is inserted through a groove 45b in the ring plate 45 and is located at the rear side of the ring plate 45, that is, the same side as the rear surface 5b of the swash plate 5. Rotation of the swash plate 5 around the axis O of the drive shaft 3 generates centrifugal force that acts on the weight 49a at the rear side of the swash plate 5.

In the compressor, the link mechanism 7 couples the swash plate 5 and the drive shaft 3 so that the swash plate 5 is able to rotate together with the drive shaft 3. Further, the pivoting of two ends of the lug arm 49 about the first pivot axis M1 and the second pivot axis M2 enables the inclination angle of the swash plate 5 to be changed from the maximum inclination angle to the minimum inclination angle shown in FIG. 4.

Referring to FIG. 1, each piston 9 includes a front end that defines a first piston head 9a and a rear end that defines a second piston head 9b. The first piston head 9a is reciprocally accommodated in the corresponding first cylinder bore 21a. The first piston head 9a defines a first compression chamber 21d with the first valve formation plate 39 in the first cylinder bore 21a. The second piston head 9b is reciprocally accommodated in the corresponding second cylinder bore 23a. The second piston head 9b defines a second compression chamber 23d with the second valve formation plate 41 in the second cylinder bore 23a.

The middle of each piston 9 includes an engagement portion 9c, which accommodates the semispherical shoes 11a and 11b. The shoes 11a and 11b convert the rotation of the swash plate 5 to the reciprocation of the piston 9. The shoes 11a and 11b correspond to a conversion mechanism of the present invention. In this manner, the first and second piston heads 9a and 9b are reciprocated in the first and second cylinder bores 21a and 23a with a stroke that is in accordance with the inclination angle of the swash plate 5.

In the compressor, a change in the inclination angle of the swash plate 5 changes the stroke of the pistons 9. This, in turn, moves the top dead center of each of the first and second piston heads 9a and 9b. More specifically, a decrease in the inclination angle of the swash plate 5 moves the top dead center of the second piston head 9b more than the top dead center of the first piston head 9a.

Referring to FIG. 5, the actuator 13 is arranged in the swash plate chamber 33. The actuator 13 is located at the rear of the swash plate 5 in the swash plate chamber 33 and is movable into the second recess 23c. The actuator 13 includes a movable body 13a, the partitioning body 13b, and the control pressure chamber 13c. The control pressure chamber 13c is defined between the movable body 13a and the partitioning body 13b.

The movable body 13a includes a rear wall 130, a circumferential wall 131, and two pulling arms 132. Each pulling arm 132 corresponds to a coupling portion of the present invention. The rear wall 130 is located at the rear of the movable body 13a and extends in the radial direction toward the outer side from the axis O of the drive shaft 3. An insertion hole 130a extends through the rear wall 130. The second small diameter portion 30b of the shaft body 30 is inserted through the insertion hole 130a. An O-ring Sic is arranged in the wall of the insertion hole 130a. The circumferential wall 131 is continuous with the outer circumference of the rear wall 130 and extends toward the front of the movable body 13a. Each pulling arm 132 is formed on the front end of the circumferential wall 131 and projects toward the front of the movable body 13a. The rear wall 130, the circumferential wall 131, and the pulling arms 132 are arranged so that the movable body 13a has the form of a cylinder that has a closed end.

The partitioning body 13b is disk-shaped and has a diameter that is substantially the same as the inner diameter of the movable body 13a. An insertion hole 133 extends through the center of the partitioning body 13b. An O-ring 51d is arranged in the wall of the insertion hole 133. Further, an O-ring 51e is arranged on the outer circumferential surface of the partitioning body 13b.

An inclination angle reduction spring 44b is located between the partitioning body 13b and the ring plate 45. More specifically, the rear end of the inclination angle reduction spring 44b contacts the partitioning body 13b, and the front end of the inclination angle reduction spring 44b contacts the ring plate 45.

The second small diameter portion 30b of the drive shaft 3 is inserted through the insertion hole 130a of the movable body 13a and the insertion hole 133 of the partitioning body 13b. Thus, when the movable body 13a is accommodated in the second recess 23c, the movable body 13a and the link mechanism 7 are located at opposite sides of the swash plate 5.

The partitioning body 13b is located in the movable body 13a at the rear of the swash plate 5 and surrounded by the circumferential wall 131. The partitioning body 13b is rotatable together with the drive shaft 3 and movable along the axis O of the drive shaft 3 in the swash plate chamber 33. In this manner, when the movable body 13a and the partitioning body 13b move along the axis O of the drive shaft 3, the inner circumferential surface of the circumferential wall 131 of the movable body 13a moves along the outer circumferential surface of the partitioning body 13b.

By surrounding the partitioning body 13b with the circumferential wall 131, the control pressure chamber 13c is formed between the movable body 13a and the partitioning body 13b. The control pressure chamber 13c is partitioned from the swash plate chamber 33 by the rear wall 130, the circumferential wall 131, and the partitioning body 13b.

A snap ring 55 is fitted to the second small diameter portion 30b. The snap ring 55 is located in the control pressure chamber 13c on the second small diameter portion 30b near a radial passage 3b, which will be described later. The snap ring 55 corresponds to a movement amount restriction portion of the present invention. Instead of the snap ring 55, for example, a flange may be arranged on the second small diameter portion 30b to serve as the movement amount restriction portion of the present invention.

A third pin 47c couples the pulling arms 132 to the lower end, which is indicated by “U” in the drawings, of the ring plate 45. The third pin 47c corresponds to the coupling portion of the present invention. Thus, the swash plate 5 is supported by the movable body 13a so as to be pivotal about the axis of the third pin 47c, namely, an action axis M3. The action axis M3 extends parallel to the first and second pivot axes M1 and M2. In this manner, the movable body 13a is coupled to the swash plate 5 so that the partitioning body 13b is opposed to the swash plate 5. In the compressor, the pulling arms 132 and the third pin 47c, which form the coupling portion, are opposed to the first pin 47a, which serves as the supporting portion, with the abutment portions 53a and 53b disposed in between. More specifically, the coupling portion (pulling arms 132 and third pin 47c) is located at the opposite side of the supporting portion (first pin 47a) as viewed from the center C of the swash plate 5. The abutment portions 53a and 53b are located between the coupling portion (pulling arms 132 and third pin 47c) and the supporting portion (first pin 47a) near the coupling portion (pulling arms 132 and third pin 47c). In other words, the abutment portions 53a and 53b are located closer to the coupling portion than the center C of the swash plate 5.

As shown in FIG. 1, an axial passage 3a extends through the second small diameter portion 30b from the rear end toward the front along the axis O of the drive shaft 3. The radial passage 3b extends through the second small diameter portion 30b from the front end of the axial passage 3a in the radial direction and opens in the outer surface of the shaft body 30. The rear end of the axial passage 3a is in communication with the pressure regulation chamber 31. The radial passage 3b is in communication with the control pressure chamber 13c. Thus, the control pressure chamber 13c is in communication with the pressure regulation chamber 31 through the radial passage 3b and the axial passage 3a.

The front end of the shaft body 30 includes a threaded portion 3c. The threaded portion 3c couples the drive shaft 3 to a pulley or an electromagnetic clutch (neither shown).

As shown in FIG. 2, the control mechanism 15 includes a bleed passage 15a, a gas supplying passage 15b, a control valve 15c, an orifice 15d, the axial passage 3a, and the radial passage 3b.

The bleed passage 15a is connected to the pressure regulation chamber 31 and the second suction chamber 27b. The control pressure chamber 13c, the pressure regulation chamber 31, and the second suction chamber 27b are in communication with one another through the bleed passage 15a, the axial passage 3a, and the radial passage 3b. The gas supplying passage 15b is connected to the pressure regulation chamber 31 and the second discharge chamber 29b. The control pressure chamber 13c, the pressure regulation chamber 31, and the second discharge chamber 29b are in communication with one another through the gas supplying passage 15b, the axial passage 3a, and the radial passage 3b. The gas supplying passage 15b includes the orifice 15d.

The control valve 15c is arranged in the bleed passage 15a. The control valve 15c is able to adjust the open degree of the bleed passage 15a based on the pressure of the second suction chamber 27b.

In the compressor, a pipe leading to the evaporator is connected to the suction port 330. A pipe leading to a condenser is connected to the discharge port 230. The condenser is connected to the evaporator by a pipe and an expansion valve. The compressor, the evaporator, an expansion valve, the condenser, and the like form the refrigeration circuit of the vehicle air conditioner. The evaporator, the expansion valve, the condenser, and the pipes are not shown in the drawings.

In the compressor, the rotation of the drive shaft 3 rotates the swash plate 5 and reciprocates each piston 9 in the corresponding first and second cylinder bores 21a and 23a. Thus, the volumes of the first and second compression chambers 21d and 23d change in accordance with the piston stroke. This repeats a suction phase that draws refrigerant gas into the first and second compression chambers 21d and 23d, a compression phase that compresses the refrigerant gas in the first and second compression chambers 21d and 23d, and a discharge phase that discharges the compressed refrigerant gas to the first and second discharge chambers 29a and 29b.

The refrigerant gas discharged to the first discharge chamber 29a flows through the first discharge communication passage 18 to the converging discharge chamber 231. In the same manner, the refrigerant gas discharged to the second discharge chamber 29b flows through the second discharge communication passage 20 to the converging discharge chamber 231. The refrigerant gas is discharged from the converging discharge chamber 231 through the discharge port 230 and delivered through a pipe to the condenser.

During the phases such as the suction phase, a compression reaction that acts to decrease the inclination angle of the swash plate 5 acts on rotational members including the swash plate 5, the ring plate 45, the lug arm 49, and the first pin 47a. A change in the inclination angle of the swash plate would increase or decrease the stroke of the pistons 9 that control the compressor displacement.

More specifically, when the control valve 15c in the control mechanism 15 shown in FIG. 2 increases the open degree of the bleed passage 15a, the pressure of the pressure regulation chamber 31 and, consequently, the pressure of the control pressure chamber 13c become substantially equal to the pressure of the second suction chamber 27b. Namely, the variable pressure difference between the control pressure chamber 13c and the swash plate chamber 33 is decreased. Thus, referring to FIG. 4, the piston compression force acting on the swash plate 5 moves the movable body 13a of the actuator 13 toward the front in the swash plate chamber 33.

As a result, in the compressor, compression reaction, which acts on the swash plate 5 through the pistons 9, urges the swash plate 5 in the direction that decreases the inclination angle. This pulls the movable body 13a toward the front of the swash plate chamber 33 with the pulling arms 132 at the action axis M3. Thus, in the compressor, the lower end U of the swash plate 5 is pivoted in the clockwise direction about the action axis M3 against the urging force of the recovery spring 44a. Further, the rear end of the lug arm 49 pivots in the counterclockwise direction about the first pivot axis M1, and the front end of the lug arm 49 pivots in the counterclockwise direction about the second pivot axis M2. Thus, the lug arm 49 moves toward the flange 430 of the first support member 43a. Consequently, the swash plate 5 is pivoted using the action axis M3 as an action point and the first pivot axis M1 as a fulcrum point. In this manner, the inclination angle of the swash plate 5 relative to a plane orthogonal to the rotation axis O of the drive shaft 3 decreases and shortens the stroke of the pistons 9 thereby decreasing the compressor displacement for each rotation of the drive shaft 3. The inclination angle of the swash plate 5 in FIG. 4 is the minimum inclination angle of the compressor.

In the compressor, the centrifugal force acting on the weight 49a is applied to the swash plate 5. Thus, in the compressor, the swash plate 5 may easily be moved in the direction that decreases the inclination angle.

When the inclination angle of the swash plate 5 decreases, the ring plate 45 comes into contact with the rear end of the recovery spring 44a. This elastically deforms the recovery spring 44a and moves the rear end of the recovery spring 44a toward the flange 430.

In the compressor, when the inclination angle of the swash plate 5 decreases and shortens the stroke of the pistons 9, the top dead center of each second piston head 9b is moved away from the second valve formation plate 41. Thus, in the compressor, the inclination angle of the swash plate 5 becomes close to zero degrees. As a result, the first compression chambers 21d slightly compress refrigerant gas, while the second compression chambers 23d do not perform compression at all.

When the control valve 15c shown in FIG. 2 decreases the open degree of the bleed passage 15a, the pressure of the refrigerant gas in the second discharge chamber 29b raises the pressure of the pressure regulation chamber 31 thereby raising the pressure of the control pressure chamber 13c. As a result, the variable pressure difference is increased. Thus, referring to FIG. 1, in the actuator 13, the movable body 13a moves toward the rear of the swash plate chamber 33 against the piston compression force acting on the swash plate 5.

As a result, in the compressor, the movable body 13a pulls rearward the section of the swash plate 5 near the lower end U with the pulling arms 132 at the action axis M3. Thus, in the compressor, the lower end U of the swash plate 5 is pivoted in the counterclockwise direction about the action axis M3. Further, the rear end of the lug arm 49 pivots in the clockwise direction about the first pivot axis M1, and the front end of the lug arm 49 pivots in the clockwise direction about the second pivot axis M2. Thus, the lug arm 49 moves away from the flange 430 of the first support member 43a. Consequently, using the action axis M3 as an action point and the first pivot axis M1 as a fulcrum point, the swash plate 5 is pivoted in a direction opposite to the direction that decreases the inclination angle, and the section at the lower end U of the swash plate 5 moves toward the partitioning body 13b. In this manner, the inclination angle of the swash plate 5 increases and lengthens the stroke of the pistons 9 thereby increasing the compressor displacement for each rotation of the drive shaft 3. The inclination angle of the swash plate 5 in FIG. 1 is the first predetermined inclination angle of the compressor. The first predetermined inclination angle is set in the compressor and smaller than the maximum inclination angle, which is mechanically set.

In this manner, when the swash plate 5 of the compressor is inclined at the first predetermined inclination angle, the abutment portions 53a and 53b contact the partitioning body 13b. This restricts the inclination angle to the first predetermined angle in the compressor.

The abutment portions 53a and 53b are separated from the center C toward the lower end U of the swash plate 5. Thus, the abutment portions 53a and 53b contact a peripheral portion of the partitioning body 13b, that is, a location separated from the insertion hole 133.

Referring to FIG. 5, when suddenly increasing the compressor displacement to the maximum, the swash plate 5 may overshoot the first predetermined inclination angle and reach the maximum inclination angle. In this case, the abutment portions 53a and 53b would come to contact and push the partitioning body 13b with a strong force.

In the compressor, however, the partitioning body 13b is movable along the axis O of the drive shaft 3. Accordingly, even if the abutment portions 53a contact or push the partitioning body 13b with a strong force, the partitioning body 13b is moved toward the rear along the axis O of the drive shaft 3 in a direction opposite to the abutment portions 53a and 53b. That is, when the inclination angle of the swash plate 5 goes beyond the first predetermined inclination angle and reaches the maximum inclination angle, the abutment portions 53a and 53b move the partitioning body 13b. When moved toward the rear, the partitioning body 13b comes into contact with the snap ring 55. This restricts further rearward movement of the partitioning body 13b.

In this manner, the compressor suppresses the shock and the pressing force of the abutment portions 53a and 53b when coming to contact or pushing the partitioning body 13b. Thus, the compressor reduces vibration when the abutment portions 53a and 53b come to contact the partitioning body 13b and limits damage to the swash plate 5, the partitioning body 13b, and the abutment portions 53a and 53b. Further, the compressor reduces noise.

Accordingly, the compressor of the first embodiment has high durability and superior quietness.

In the compressor, the partitioning body 13b is moved along the axis O of the drive shaft 3. Thus, even though the swash plate 5 and the partitioning body 13b are located near each other, open space for the abutment portions 53a and 53b may be obtained between the swash plate 5 and the partitioning body 13b. This allows the compressor to be reduced in length in the axial direction.

Further, the compressor includes the snap ring 55 on the small diameter portion 30b of the shaft body 30. Thus, contact of the partitioning body 13b with the snap ring 55 restricts the movement amount of the partitioning body 13b along the axis O of the drive shaft 3. This limits unnecessary rearward movement of the partitioning body 13b along the axis O of the drive shaft 3 and keeps the radial passage 3b unexposed to the outside of the control pressure chamber 13c, that is, unexposed to the swash plate chamber 33.

The snap ring 55 is located in the control pressure chamber 13c near the radial passage 3b. Thus, there is no need to obtain open space dedicated for the snap ring 55 in the control pressure chamber 13c, and the control pressure chamber 13c may be reduced in size. This also allows the compressor to be reduced in length in the axial direction.

In the compressor, the partitioning body 13b is movable along the axis O of the drive shaft 3. This allows the movable body 13a to easily move relative to the partitioning body 13b when changing the inclination angle of the swash plate 5. Thus, the compressor is able to smoothly change the inclination angle of the swash plate 5.

Second Embodiment

A compressor of a second embodiment includes two abutment portions 57a and 57b shown in FIG. 6 instead of the two abutment portions 53a and 53b of the compressor in the first embodiment. Referring to FIG. 7A, the abutment portions 57a and 57b are formed on the surface of the ring plate 45 located at the same side as the rear surface 5b of the swash plate 5. The abutment portions 57a and 57b are located proximate to the center C of the swash plate 5, that is, closer to the center C than the lower end U of the swash plate 5. In the same manner as the abutment portions 53a and 53b in the compressor of the first embodiment, the abutment portions 57a and 57b are symmetric relative to the center line L that extends through the center C. In the compressor, the pulling arms 132 and the third pin 47c, which form the coupling portion, and the first pin 47a, which serves as the supporting portion, are located at opposite sides of the abutment portions 57a and 57b.

The abutment portions 57a and 57b are identically shaped, triangular, and project toward the rear from the ring plate 45 as shown in FIG. 7B. The abutment portions 57a and 57b are larger than the abutment portions 53a and 53b in the compressor of the first embodiment.

Referring to FIG. 8, when the swash plate 5 is inclined at a second predetermined inclination angle, the abutment portions 57a and 57b contact the partitioning body 13b. The second predetermined inclination angle is greater than the minimum inclination angle of the swash plate 5 (refer to FIG. 6) and less than the mechanically set maximum inclination angle of the swash plate 5 (refer to FIG. 9). Other components of the compressor are the same as those in the compressor of the first embodiment. Same reference numerals are given to those components that are the same as the corresponding components of the first embodiment. Such components will not be described in detail.

In the compressor, as shown in FIG. 8, when the swash plate 5 is inclined at the second predetermined inclination angle, the abutment portions 57a and 57b contact the partitioning body 13b. Referring to FIG. 9, when the inclination angle of the swash plate 5 changes from the second predetermined inclination angle to the maximum inclination angle, the abutment portions 57a and 57b, which are in contact with the partitioning body 13b, push the partitioning body 13b. Thus, as the inclination angle of the swash plate 5 changes from the second predetermined inclination angle to the maximum inclination angle, the abutment portions 57a and 57b contact and push the partitioning body 13b, and the movable body 13a moves toward the rear along the axis O of the drive shaft 3. In this manner, when the inclination angle of the swash plate 5 increases from the second predetermined inclination angle to the maximum inclination angle, the abutment portions 57a and 57b push and move the partitioning body 13b.

In the compressor, as described above, the inclination angle of the swash plate 5 is increased by increasing the pressure of the control pressure chamber 13c, that is, increasing the variable pressure difference between the control pressure chamber 13c and the swash plate chamber 33. As shown in the graph of FIG. 10, the increasing rate of the variable pressure difference from the second predetermined inclination angle to the maximum inclination angle is larger than the increasing rate of the variable pressure difference when the inclination angle comes closer to the second predetermined inclination angle from the minimum inclination angle. That is, the variable pressure difference needs to be further increased to increase the inclination angle from the second predetermined inclination angle to the maximum inclination angle. In this manner, the pressure of the control pressure chamber 13c needs to be further increased in order to further increase the variable pressure difference and thereby increase the inclination angle from the second predetermined inclination angle to the maximum inclination angle.

If the abutment portions 57a and 57b were omitted from the compressor of the present embodiment and, at the same time, the partitioning body 13b arranged on the second small diameter portion 30b were immovable along the axis O, this would lower the increasing rate of the variable pressure difference for changing the inclination angle of the swash plate 5 from the second predetermined inclination angle to the maximum inclination angle, as shown in a flat dashed line in FIG. 10. This means that the inclination angle may be changed in a certain range even if the variable pressure difference is substantially the same. Thus, it would be difficult to control the swash plate 5 and obtain the desired inclination angle between the compressor displacement corresponding to the second predetermined inclination angle and the compressor displacement corresponding to the maximum inclination angle.

In this respect, the abutment portions 57a and 57b in the compressor of the present embodiment continue to contact and push the partitioning body 13b from when the inclination angle of the swash plate 5 reaches the second predetermined inclination angle to when the swash plate 5 reaches the maximum inclination angle. Thus, as shown in the solid line in FIG. 10, the compressor of the present embodiment allows the variable pressure difference to be increased in a preferred manner for changing the inclination angle from the second predetermined inclination angle to the maximum inclination angle. That is, in the compressor, the variable pressure difference smoothly increases from the minimum inclination angle to the maximum inclination angle. This allows the compressor to easily control the torque of the vehicle engine or the like while varying the compressor displacement in a preferred manner. Other operations of the compressor are the same as the compressor of the first embodiment.

The present invention is not restricted to the first and second embodiments described above. It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms.

The ring plate 45 of the first embodiment may include only one of the abutment portions 53a and 53b. In the same manner, the ring plate 45 of the second embodiment may include only one of the abutment portions 57a and 57b.

In the control mechanism 15, the control valve 15c may be arranged in the gas supplying passage 15b, and the orifice 15d may be arranged in the bleed passage 15a. In this case, the control valve 15c allows for adjustment of the open degree of the gas supplying passage 15b. This enables the control pressure chamber 13c to be promptly increased to a high pressure by the pressure of the refrigerant gas in the second discharge chamber thereby promptly increasing the compressor displacement.

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.

VARIABLE DISPLACEMENT SWASH PLATE COMPRESSOR

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CPC

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