The present invention relates to a double-headed piston type swash plate compressor including a double-headed piston that is coupled to a swash plate and reciprocated by a stroke corresponding to the inclination angle of the swash plate.
Japanese Laid-Open Patent Publication No. 5-172052 describes a double-headed piston type swash plate compressor (hereinafter simply referred to as the “compressor”). Referring to
A bore 102h extends through the central portion of the cylinder block 102. A rotation shaft 106, which extends through the front housing 104, is set in the bore 102h. Cylinder bores 107 are formed in the cylinder block 102 around the rotation shaft 106. Each cylinder bore 107 accommodates a double-headed piston 108. A crank chamber 102a is defined in the cylinder block 102. The crank chamber 102a accommodates a swash plate 109, which is rotated by drive force from the rotation shaft 106. The inclination angle of the swash plate 109 is changeable. Each double-headed piston 108 is coupled to the swash plate 109 by shoes 110. The front housing 104 includes suction chambers 104a and discharge chambers 104b. The rear housing 105 includes suction chambers 105a and discharge chambers 105b. Each suction chamber 104a and each discharge chamber 104b are in communication with a corresponding one of the cylinder bores 107. Each suction chamber 105a and each discharge chamber 105b are in communication with a corresponding one of the cylinder bores 107.
An actuator 111 is arranged in the rear portion of the bore 102h in the cylinder block 102. The actuator 111 accommodates the rear end of the rotation shaft 106. The rear end of rotation shaft 106 is slidable in the actuator 111 relative to the actuator 111. The circumference of the actuator 111 is slidable relative to the bore 102h. A pushing spring 112 is arranged between the actuator 111 and the valve plate 103b. The pushing spring 112 pushes the actuator 111 toward the distal end of the rotation shaft 106, that is, toward the left side as viewed in
The bore 102h extends toward the rear from the actuator 111 and is in communication through a hole in the valve plate 103b with a pressure regulation chamber 117 (control pressure chamber), which is formed in the rear housing 105. The pressure regulation chamber 117 is in communication with the discharge chambers 105b through a pressure regulation circuit 118. A pressure control valve 119 is arranged in the pressure regulation circuit 118. The pressure of the pressure regulation chamber 117 regulates the movement amount of the actuator 111.
In the bore 102h, a first coupling body 114 is arranged in front of the actuator 111 with a thrust bearing 113 arranged in between. The rotation shaft 106 extends through the first coupling body 114. The rotation shaft 106 is slidable relative to the first coupling body 114. Slidable movement of the actuator 111 moves the first coupling body 114 along the rotation shaft 106. A first arm 114a extends toward the outer side from the circumference of the first coupling body 114. The first arm 114a includes a first pin guide groove 114h that extends diagonally relative to the axial direction of the rotation shaft 106.
In the bore 102h, a second coupling body 115 (drive force transmission member) is arranged in front of the swash plate 109. The second coupling body 115 is fixed to the rotation shaft 106 to rotate integrally with the rotation shaft 106. A second arm 115a extends toward the outer side from the circumference of the second coupling body 115 at a position that is substantially symmetric to the first arm 114a. The second arm 115a includes a second pin guide groove 115h that extends diagonally relative to the axial direction of the rotation shaft 106.
The swash plate 109 includes a rear surface, which is closer to the first coupling body 114, and a front surface, which is closer to the second coupling body 115. Two first supports 109a extend toward the first arm 114a from the rear surface of the swash plate 109. The first arm 114a is located between the two first supports 109a. A first coupling pin 114p, which is inserted through the first pin guide groove 114h, pivotally couples the two supports 109a and the first arm 114a.
Two second supports 109b extend toward the second arm 115a from the front surface of the swash plate 109. The second arm 115a is located between the two second supports 109b. A second coupling pin 115p, which is inserted through the second pin guide groove 115h, pivotally couples the two supports 109b and the second arm 115a. The swash plate 109 is rotated by drive force received from the rotation shaft 106 through the second coupling body 115.
When decreasing the displacement of the compressor 100, the pressure control valve 119 is closed to lower the pressure of the pressure regulation chamber 117. As a result, the pressure of the crank chamber 102a becomes higher than the sum of the pressure of the pressure regulation chamber 117 and the urging force of the pushing spring 112. This moves the actuator 111 toward the valve plate 103b as shown in
When increasing the displacement of the compressor 100, the pressure control valve 119 is opened to draw high-pressure gas (control gas) from the discharge chambers 105b through the pressure regulation circuit 118 and into the pressure regulation chamber 117 to increase the pressure of the pressure regulation chamber 117. As a result, the sum of the pressure of the pressure regulation chamber 117 and the urging force of the pushing spring 112 becomes higher than the pressure of the crank chamber 102a. This moves the actuator 111 toward the swash plate 109 as shown in
In the compressor 100 of the above embodiment, each cylinder bore 107 accommodates one of the double-headed pistons 108. In such a structure, each double-headed piston 108 reciprocates in the cylinder block 102 at the outer side of the rotation shaft 106 in the radial direction. This restricts the positions of the second coupling body 115, the actuator 111, and the first coupling body 114 in the cylinder block 102 to the radially inner side of the region where the double-headed pistons 108 reciprocate. Further, the compressor 100 needs to be compact to fit into the space that is available in a vehicle. This restricts the area in the cylinder block 102 that can be occupied by the second coupling body 115, the actuator 111, and the first coupling body 114. It is thus desirable that the area occupied in the cylinder block 102 by the second coupling body 115, the actuator 111, and the first coupling body 114 be minimized to limit enlargement of the compressor 100. However, when the actuator 111 is reduced in size, the swash plate 109 may not be able to smoothly change the inclination angle.
It is an object of the present invention to provide a double-headed piston type swash plate compressor that smoothly changes the inclination angle of the swash plate while limiting enlargement of the compressor.
To achieve the above object, one aspect of the present invention provides a double-headed piston type swash plate compressor including a first cylinder block and a second cylinder block, a rotation shaft, a double-headed piston, a crank chamber, a drive force transmission member, a swash plate, a movable body, a control pressure chamber, and a support. The first and second cylinder blocks form a housing. The first cylinder block includes a first cylinder bore, and the second cylinder block includes a second cylinder bore. The double-headed piston is accommodated in the first cylinder bore and the second cylinder bore. The double-headed piston is movable back and forth in the first cylinder bore and the second cylinder bore. The drive force transmission member is accommodated in the crank chamber and fixed to the rotation shaft. The drive force transmission member is rotatable integrally with the rotation shaft. The swash plate is accommodated in the crank chamber. The swash plate is rotated when receiving drive force from the rotation shaft through the drive force transmission member. The swash plate is inclined at an angle relative to the rotation shaft that is changeable. The swash plate is coupled to the double-headed piston. The double headed piston moves back and forth with a stroke that is in accordance with the inclination angle of the swash plate. The movable body is coupled to the swash plate. The movable body is capable of changing the inclination angle of the swash plate. The control pressure chamber is defined by the movable body in the housing. The control pressure chamber draws in control gas that changes the pressure in the control pressure chamber to move the movable body in an axial direction of the rotation shaft. The support is located on the swash plate and supported by the rotation shaft. The drive force transmission member and the movable body are located at a first side of the swash plate in the axial direction of the rotation shaft. The support is located at a second side of the swash plate that is opposite from the first side in the axial direction of the rotation shaft. The swash plate is supported by the rotation shaft through the drive force transmission member, the movable body, and the support. The inclination angle of the swash plate relative to the rotation shaft is set by the drive force transmission member, the movable body, and the support.
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.
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:
A first embodiment of the present invention will now be described with reference to
The left side, right side, upper side, and lower side as viewed in
A first valve-port formation body 16 is arranged between the front housing 14 and the first cylinder block 12. A second valve-port formation body 17 is arranged between the rear housing 15 and the second cylinder block 13.
A suction chamber 14a and a discharge chamber 14b are defined between the front housing 14 and the first valve-port formation body 16. The discharge chamber 14b is located at the radially outer side of the suction chamber 14a. A suction chamber 15a and a discharge chamber 15b are defined between the rear housing 15 and the second valve-port formation body 17. The rear housing 15 includes a pressure regulation chamber 15c. The pressure regulation chamber 15c is located at a central portion of the rear housing 15. The suction chamber 15a is located at the radially outer side of the pressure regulation chamber 15c. The discharge chamber 15b is located at the radially outer side of the suction chamber 15a. A discharge passage (not shown) connects the discharge chambers 14b and 15b. The discharge passage is connected to an external refrigerant circuit (not shown).
The first valve-port formation body 16 includes a suction port 16a, which is in communication with the suction chamber 14a, and a discharge port 16b, which is in communication with the discharge chamber 14b. The second valve-port formation body 17 includes a suction port 17a, which is in communication with the suction chamber 15a, and a discharge port 17b, which is in communication with the discharge chamber 15b. Each of the suction ports 16a and 17a includes a suction valve mechanism (not shown), and each of the discharge ports 16b and 17b includes a discharge valve mechanism (not shown).
A rotation shaft 21 is held to be rotatable in the housing 11. The rotation shaft 21 includes a front end portion inserted into a shaft hole 12h extending through the first cylinder block 12. The front end portion of the rotation shaft 21 is located at the front side of the housing 11 and is defined by the portion of the rotation shaft 21 near the front end in the direction of the axis L (axial direction of rotation shaft 21). The front end of the rotation shaft 21 is located in the front housing 14. Further, the rotation shaft 21 includes a rear end portion inserted into a shaft hole 13h extending through the second cylinder block 13. The rear end portion of the rotation shaft 21 is located at the rear side of the housing 11 and is defined by the portion of the rotation shaft 21 near the rear end in the axial direction of rotation shaft 21. The rear end of the rotation shaft 21 is located in the pressure regulation chamber 15c.
The front end portion of the rotation shaft 21 is supported to be rotatable by the first cylinder block 12 in the shaft hole 12h. The rear end portion of the rotation shaft 21 is supported to be rotatable by the second cylinder block 13 in the shaft hole 13h. A shaft seal 22, which is of a lip seal type, is arranged between the front housing 14 and the rotation shaft 21.
The first cylinder block 12 and the second cylinder block 13 define a crank chamber 24 in the housing 11. The crank chamber 24 accommodates a swash plate 23, which is rotated by drive force from the rotation shaft 21. The swash plate 23 is inclinable relative to the axial direction of the rotation shaft 21. The swash plate 23 includes an insertion hole 23a through which the rotation shaft 21 can be inserted. The swash plate 23 includes an upper half located at the upper side of the center O and a lower half located at the lower side of the center O.
The first cylinder block 12 includes first cylinder bores 12a formed around the rotation shaft 21.
Two shoes 26 couple each double-headed piston 25 to the peripheral portion of the swash plate 23. The shoes 26 convert rotation of the swash plate 23, which is rotated by the rotation shaft 21, to linear reciprocation of the double-headed piston 25. The double-headed piston 25 and the first valve-port formation body 16 define a first compression chamber 20a in each first cylinder bore 12a. The double-headed piston 25 and the second valve-port formation body 17 define a second compression chamber 20b in each second cylinder bore 13a.
The first cylinder block 12 includes a first large diameter hole 12b, which is in communication with the shaft hole 12h and has a larger diameter than the shaft hole 12h. The first large diameter hole 12b is in communication with the crank chamber 24. The crank chamber 24 and the suction chamber 14a are in communication through a suction passage 12c, which extends through the first cylinder block 12 and the first valve-port formation body 16.
The second cylinder block 13 includes a second large diameter hole 13b, which is in communication with the shaft hole 13h and has a larger diameter than the shaft hole 13h. The second large diameter hole 13b is in communication with the crank chamber 24. The crank chamber 24 and the suction chamber 15a are in communication through a suction passage 13c, which extends through the second cylinder block 13 and the second valve-port formation body 17.
The circumferential wall of the second cylinder block 13 includes an inlet 13s, which is connected to an external refrigerant circuit. Refrigerant gas is drawn into the crank chamber 24 through the inlet 13s. Then, the refrigerant gas is drawn through the suction passages 12c and 13c into the suction chambers 14a and 15a. In this manner, the suction chambers 14a and 15a and the crank chamber 24 form a suction pressure region. The pressure is substantially equal throughout the suction pressure region.
An annular flange 21f projects from the rotation shaft 21 in the first large diameter hole 12b. A thrust bearing 27a is arranged between the flange 21f and the first cylinder block 12 in the axial direction of the rotation shaft 21.
An annular drive force transmission member 31 is fixed to the rotation shaft 21 between the flange 21f and the swash plate 23. The drive force transmission member 31 is rotatable integrally with the rotation shaft 21. The drive force transmission member 31 includes an annular main body 31a and two arms 31b, which project from an end face of the main body 31a toward the swash plate 23. A bottom portion defining a guide surface 31c extends between the two arms 31b.
A projection 23c projects from the upper half of the swash plate 23 toward the drive force transmission member 31. The projection 23c is located between the two arms 31b. The projection 23c is movable along the guide surface 31c between the two arms 31b. The projection 23c includes a distal end portion that is capable of sliding on the guide surface 31c. The projection 23c and the guide surface 31c cooperate to allow the swash plate 23 to incline in the axial direction of the rotation shaft 21. The two arms 31b transmit drive force from the rotation shaft 21 to the projection 23c. This rotates the swash plate 23. When inclining the swash plate 23 in the axial direction of the rotation shaft 21, the distal end portion of the projection 23c slides on the guide surface 31c.
A movable body 32 is arranged between the flange 21f and the drive force transmission member 31. The movable body 32 is tubular and has a closed end. Further, the movable body 32 is movable in the axial direction of the rotation shaft 21 relative to the drive force transmission member 31. The drive force transmission member 31 and the movable body 32 are accommodated in the first cylinder block 12 and the second cylinder block 13 in a region located at the inner side of where the double-headed pistons 25 reciprocate in the radial direction of the rotation shaft 21. The drive force transmission member 31 and the movable body 32 are arranged at the front side of the swash plate 23 in the axial direction of the rotation shaft 21.
The movable body 32 includes an annular end portion 32a and a tubular portion 32b. The end portion 32a includes an insertion hole 32e through which the rotation shaft 21 is inserted. The tubular portion 32b extends from the outer circumference of the end portion 32a in the axial direction of the rotation shaft 21 and covers the rotation shaft 21. The movable body 32 moves in the axial direction of the rotation shaft 21 as an inner circumferential surface 321b of the tubular portion 32b slides along an outer circumferential surface 311a of the main body 31a of the drive force transmission member 31. The movable body 32 is rotatable integrally with the rotation shaft 21. A seal 33 seals the gap between the inner circumferential surface 321b of the tubular portion 32b and the main body 31a of the drive force transmission member 31.
A protrusion 32f projects from the end portion 32a where the rotation shaft 21 is inserted toward the drive force transmission member 31 in the axial direction of the rotation shaft 21. An inner circumferential surface of the protrusion 32f includes an annular holding groove 32d. The holding groove 32d receives a seal 34 that seals the gap between the wall of the insertion hole 32e and the rotation shaft 21. The drive force transmission member 31 and the movable body 32 define a control pressure chamber 35.
The rotation shaft 21 includes a first in-shaft passage 21a, which extends in the axial direction of the rotation shaft 21. The first in-shaft passage 21a includes a rear end that opens to the pressure regulation chamber 15c. Further, the rotation shaft 21 includes a second in-shaft passage 21b, which extends in the radial direction of the rotation shaft 21. The second in-shaft passage 21b includes a rear end that is in communication with a distal end of the first in-shaft passage 21a. The control pressure chamber 35 and the pressure regulation chamber 15c are in communication through the first in-shaft passage 21a and the second in-shaft passage 21b.
As shown in
The pressure in the control pressure chamber 35 is adjusted by drawing refrigerant gas from the discharge chamber 15b into the control pressure chamber 35 through the gas supplying passage 37, the pressure regulation chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b and discharging refrigerant gas from the control pressure chamber 35 into the suction chamber 15a through the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure regulation chamber 15c, and the bleeding passage 36. The pressure difference of the control pressure chamber 35 and the crank chamber 24 moves the movable body 32 relative to the drive force transmission member 31 in the axial direction of the rotation shaft 21. Thus, the refrigerant gas drawn into the control pressure chamber 35 moves the movable body 32 in the axial direction of the rotation shaft 21.
As shown in
A tubular member 42 is arranged integrally on the rear surface of the swash plate 23, that is, the end face of the swash plate 23 opposite to the drive force transmission member 31. The tubular member 42 includes a through hole 42h that is in communication with the insertion hole 23a of the swash plate 23. The tubular member 42 includes two insertion holes 42a that open in the through hole 42h. A cylindrical abutment pin 43 is inserted through the two insertion holes 42h. The abutment pin 43 bridges different wall portions of the through hole 42h so as to extend across the interior of the through hole 42h. The abutment pin 43 is located at the rear side of the swash plate 23 in the axial direction of the rotation shaft 21.
The rotation shaft 21 includes a guide surface 44 that guides the abutment pin 43 as the inclination angle of the swash plate 23 changes. The abutment pin 43 slides and moves on the guide surface 44. The guide surface 44 is linearly sloped to approach the axis L of the rotation shaft 21 at locations farther from the swash plate 23.
In the compressor 10, a decrease in the open amount of the control valve 37s reduces the amount of refrigerant gas drawn into the control pressure chamber 35 from the discharge chamber 15b through the gas supplying passage 37, the pressure regulation chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b. The discharge of refrigerant gas from the control pressure chamber 35 to the suction chamber 15a through the second in-shaft passage 21b, the first in-shaft passage 21a, the pressure regulation chamber 15c, and the bleeding passage 36 results in the pressure of the control pressure chamber 35 approaching the pressure of the suction chamber 15a. A decrease in the pressure difference between the control pressure chamber 35 and the crank chamber 24 moves the movable body 32 in the axial direction of the rotation shaft 21 so that the end portion 32a approaches the drive force transmission member 31.
Referring to
An increase in the open amount of the control valve 37s increases the amount of refrigerant gas drawn into the control pressure chamber 35 from the discharge chamber 15b through the gas supplying passage 37, the pressure regulation chamber 15c, the first in-shaft passage 21a, and the second in-shaft passage 21b. Thus, the pressure of the control pressure chamber 35 approaches the pressure of the discharge chamber 15b. The increase in the pressure difference between the control pressure chamber 35 and the crank chamber 24 moves the movable body 32 in the axial direction of the rotation shaft 21 so that the end portion 32a moves away from the drive force transmission member 31.
Referring to
Referring to
The operation of the first embodiment will now be described.
Referring to
On the outer surface of the rotation shaft 21, the guide surface 44 contacts the swash plate 23. However, surfaces of the rotation shaft 21 other than the guide surface 44 do not contact the swash plate 23. The wall surface of the insertion hole 23a includes a portion 231a located toward the guide surface 44. The insertion hole 23a is formed so that the portion 231a does not contact the rotation shaft 21. As shown in
Due to the balance of forces, the reaction force F2 of the force F1, which acts on the guide surface 44 of the rotation shaft 21, acts on the swash plate 23 from the guide surface 44 through the abutment pin 43. The moment acting about the portion where the drive force transmission member 31 and the swash plate 23 are coupled, that is, the portion where the projection 23c and the guide surface 31c are in contact, will now be discussed. The reaction force F2 increases as the portion where the reaction force F2 acts on becomes closer to the portion where the drive force transmission member 31 and the swash plate 23 are coupled.
In the present embodiment, the abutment pin 43 is located at the rear side of the swash plate 23 in the axial direction of the rotation shaft 21. That is, the abutment pin 43 and the drive force transmission member 31 are located on opposite sides of the swash plate 23 in the axial direction of the rotation shaft 21. This separates the portion where the reaction force F2 acts on as far as possible from the coupling portion of the drive force transmission member 31 and the swash plate 23. Further, the reaction force F2 is minimized in the moment of the force acting on the swash plate 23 about the coupling portion of the drive force transmission member 31 and the swash plate 23. Thus, the inclination angle of the swash plate 23 is smoothly changed.
Further, in the axial direction of the rotation shaft 21, the abutment pin 43 is located on one side of the swash plate 23, and the drive force transmission member 31 and the movable body 32 are located on the opposite side of the swash plate 23. Thus, in comparison with when the abutment pin 43 is located at the front side of the swash plate 23 in the axial direction of the rotation shaft 21, components may be laid out in a scattered manner. This allows for reduction in the area occupied by the drive force transmission member 31 and the movable body 32 at the radially inner side of the region where the double-headed pistons 25 reciprocate.
Further, the abutment pin 43 is located in a portion separated from the drive force transmission member 31 and the movable body 32. This ensures an area in the axial direction of the rotation shaft 21 where the abutment pin 43 may be arranged. Thus, the abutment pin 43 is greatly separated from the coupling portion of the drive force transmission member 31 and the swash plate 23.
In the present embodiment, the upper end of the swash plate 23 is located farthest from the axis in the upper half of the swash plate 23. More specifically, the upper end of the swash plate 23 is the portion of the swash plate 23 where the outer diameter is largest and is located on the opposite side of the abutment pin 43 with respect to the rotation shaft 21. Distance H1 is the distance between the upper end of the swash plate 23 and the axis L of the rotation shaft 21. The lower end of the swash plate 23 is located farthest from the axis in the lower half of the swash plate 23. More specifically, the lower end of the swash plate 23 is the portion where the outer diameter is largest and located on the lower half of the swash plate 23 at the same side as the abutment pin 43 with respect to the rotation shaft 21. Distance H2 is the distance between the lower end of the swash plate 23 and the axis L of the rotation shaft 21. A change in the distance H1 and the distance H2 changes the inclination angle of the swash plate 23.
In
An example in which the abutment pin 43 guides the guide surface 44 under a situation in which the center O of the swash plate 23 is located above the axis L of the rotation shaft 21, that is, at the opposite side of the abutment pin 43 when the swash plate 23 is located at a position corresponding to the maximum inclination position θmax, and the center O of the swash plate 23 and the axis of the rotation shaft 21 coincide with each other when the swash plate 23 is located at a position corresponding to the minimum inclination position θmin will now be discussed. In this case, when the inclination angle of the swash plate 23 is changing, the center O of the swash plate 23 is greatly separated toward the upper side from the axis L of the rotation shaft 21.
This results in the maximum distance between the upper end of the swash plate 23 and the axis L being greater than the maximum distance between the lower end of the swash plate 23 and the axis L. Consequently, when the upper end of the swash plate 23 is most separated from the axis L, the swash plate 23 may interfere with the double-headed pistons 25. Thus, to avoid interference between the swash plate 23 and each double-headed piston 25, a cutout portion (recess) needs to be formed in the double-headed piston 25 near the swash plate 23.
In the present embodiment, the abutment pin 43 is guided by the guide surface 44 so that the center O of the swash plate 23 and the axis of the rotation shaft 21 coincide with each other when the swash plate 23 is located at the position corresponding to the maximum inclination angle θmax and the center O of the swash plate 23 is located at the lower side of the axis L, that is, toward the abutment pin 43, when the swash plate 23 is located at the position corresponding to the minimum inclination angle θmin. Thus, as shown by the sold line L10 in
In
As shown in
The first embodiment has the advantages described below.
(1) The abutment pin 43 receives reaction force F2 that acts on the swash plate 23 from the rotation shaft 21. The abutment pin 43 is located at the rear side of the swash plate 23 in the axial direction of the rotation shaft 21. That is, the abutment pin 43 and the drive force transmission member 31 are arranged on opposite sides of the swash plate 23 in the axial direction of the rotation shaft 21. Thus, when reaction force F2 from the rotation shaft 21 acts on the swash plate 23, the portion where the reaction force F2 acts on is separated as far as possible from the coupling portion of the drive force transmission member 31 and the swash plate 23. When taking into consideration moment balancing of the force applied to the swash plate 23 about the coupling portion of the drive force transmission member 31 and the swash plate 23, the reaction force F2 acting on the swash plate 23 may be minimized. Thus, the inclination angle of the swash plate 23 may be smoothly changed. Further, the abutment pin 43 is arranged on the opposite side of the drive force transmission member 31 and the movable body 32 from the swash plate 23 in the axial direction of the rotation shaft 21. Hence, the area occupied by the drive force transmission member 31 and the movable body 32 at the radially inner side of the region where the double-headed pistons 25 reciprocate may be reduced in size compared to when the abutment pin 43 is located at the front side of the swash plate 23 in the axial direction of the rotation shaft 21. As a result, the inclination angle of the swash plate 23 may be smoothly changed while limiting enlargement in the size of the compressor 10.
(2) The rotation shaft 21 includes the guide surface 44 that guides the abutment pin 43 when the inclination angle of the swash plate 23 changes. The guide surface 44 is formed to guide the abutment pin 43 so that the center O of the swash plate 23 and the axis of the rotation shaft 21 coincide with each other when the swash plate 23 is located at a position corresponding to the maximum inclination angle θmax and the center O of the swash plate 23 is located closer to the abutment pin 43 than the axis L of the rotation shaft 21 when the swash plate 23 is located at a position corresponding to the minimum inclination angle θmin. Thus, the center O of the swash plate 23 does not greatly move away from the axis L of the rotation shaft 21 toward the side opposite to the abutment pint 43 from the rotation shaft 21 when the inclination angle of the swash plate 23 is being changed. This eliminates the need for the formation of a cutout portion in each double-headed piston 25 to avoid interference of the swash plate 23 with the double-headed piston 25. Further, the strength of the double-headed piston 25 may be ensured.
A second embodiment of the present invention will now be described with reference to
Referring to
The operation of the second embodiment will now be described.
In the contact portion of the abutment pin 43 and the slope 44a, force F3 from the swash plate 23 acts on the slope 44a in the normal direction of the slope 44a through the abutment pin 43. In the contact portion of the slope 44a and the abutment pin 43, due to the balance of forces, force F4, which is the reaction force of force F3, from the slope 44a acts on the swash plate 23 through the abutment pin 43. The force F4 is divided into force F4y, which exerts in a direction (vertical direction) perpendicular to the movement direction of the movable body 32, and force F4x, which exerts along the movement direction (horizontal direction) of the movable body 32.
When controlling the inclination angle of the swash plate 23 under a situation in which the inclination angle of the swash plate 23 is close to the minimum inclination angle θmin, the pressure of the control pressure chamber 35 is close to the suction pressure. The pressure in the control pressure chamber 35 does not become lower than the suction pressure. Accordingly, if the necessary pressure of the control pressure chamber 35 that allows for the swash plate 23 to have the inclination angle close to the minimum inclination angle θmin is set to be lower than the suction pressure, the swash plate 23 cannot have the inclination angle close to the minimum inclination angle θmin.
Referring to
In
When the inclination angle of the swash plate 23 is close to the minimum inclination angle θmin, the force F4x of the second embodiment is greater than the similar force in the first embodiment, that is, the force exerting in the movement direction of the movable body 32 that acts on the contact portion of the guide surface 44 and the abutment pin 43. As a result, as shown in
When the swash plate 23 controls the inclination angle of the swash plate 23 under a situation in which the inclination angle of the swash plate 23 is close to the maximum inclination angle θmax, the pressure of the control pressure chamber 35 is close to the discharge pressure. The pressure in the control pressure chamber 35 does not become higher than the discharge pressure. Accordingly, if the necessary pressure of the control pressure chamber 35 that allows for the swash plate 23 to have the inclination angle close to the maximum inclination angle θmax is set to be higher than the discharge pressure, the swash plate 23 cannot have the inclination angle close to the maximum inclination angle θmax.
As shown in
When the inclination angle of the swash plate 23 is close to the maximum inclination angle θmax, the force F4x of the second embodiment is smaller than the similar force in the first embodiment, that is, the force exerting in the movement direction of the movable body 32 that acts on the contact portion of the guide surface 44 and the abutment pin 43. As a result, as shown in
Accordingly, in addition to advantages (1) and (2) of the first embodiment, the second embodiment has the advantages described below.
(3) The guide surface 44 includes the slope 44a that guides the abutment pin 43 away from the axis L of the rotation shaft 21 as the movable body 32 moves in the direction in which the inclination angle of the swash plate 23 increases from the minimum inclination angle θmin. As the movable body 32 moves in the direction in which the inclination angle of the swash plate 23 increases, the sloped angle of the slope 44a gradually decreases at the contact portion between the abutment pin 43 and the slope 44a. In the second embodiment, the sloped angle of the slope 44a at the contact portion between the abutment pin 43 and the slope 44a when the swash plate 23 has the minimum inclination angle θmin increases relative to that in the first embodiment. In this case, the force F4x in the second embodiment increases relative to that in the first embodiment. The force F4x is transmitted from the slope 44a to the movable body 32 through the abutment pin 43 and the swash plate 23. The force F4x transmitted to the movable body 32 may obstruct the movement of the movable body 32 when moving the movable body 32 in the direction that increases the inclination angle of the swash plate 23 from the minimum inclination angle θmin. Thus, in the second embodiment, the movable body 32 cannot be moved unless the pressure of the control pressure chamber 35 is increased relative to that in the first embodiment. As a result, as shown in
Accordingly, the second embodiment overcomes the effects due to the design conditions for the structural members of the compressor that would be taken into consideration when determining the necessary pressure of the control pressure chamber 35 that allows for the swash plate 23 to have the intended inclination angle. Second embodiment improves the flexibility in the design of the compressor.
(4) As the movable body 32 moves in the direction in which the inclination angle of the swash plate 23 increases, the sloped angle of the slope 44a gradually decreases at the contact portion between the abutment pin 43 and the slope 44a. This decreases the force F4x acting on the contact portion between the slope 44a and the abutment pin 43 as the movable body 32 moves in the direction in which the inclination angle of the swash plate 23 increases. As a result, when the movable body 32 moves in the direction in which the inclination angle of the swash plate 23 increases, the force that obstructs movement of the movable body 32 may be decreased. This decreases the necessary pressure in the control pressure chamber 35 that allows for the movement of the movable body 32. In the second embodiment, the sloped angle of the slope 44a at the contact portion between the abutment pin 43 and the slope 44a when the swash plate 23 has the maximum inclination angle θmax decreases relative to that in the first embodiment. As a result, as shown in
(5) In a conventional structure in which the double-headed piston 25 is accommodated in the first cylinder bore 12a and the second cylinder bore 13a to be movable back and forth, when changing the inclination angle of the swash plate 23, although the dead volume of the second compression chamber 20b is not drastically increased, the dead volume is increased by a certain extent. The dead volume of the second compression chamber 20b refers to the clearance between the double-headed piston 25 and the second valve-port formation body 17. However, in the second embodiment, the shape of the slope 44a allows for the position of the swash plate 23 to be moved in the axial direction. Thus, even when the inclination angle of the swash plate 23 is changed, depending on the shape of the slope 44a, the dead volume of the second compression chamber 20b may be kept fixed. That is, the dead volume may be adjusted by setting a suitable shape for the slope 44a.
A third embodiment of the present invention will now be described with reference to
Referring to
The operation of the third embodiment will now be described.
In a structure in which the double-headed piston 25 is accommodated in the first cylinder bore 12a and the second cylinder bore 13a to be movable back and forth, compression reaction forces P1 and P2 from the double-headed piston 25 act on the swash plate 23 to decrease the inclination angle of the swash plate 23.
Further, in a structure in which the double-headed piston 25 is accommodated in the first cylinder bore 12a and the second cylinder bore 13a to be movable back and forth, as the inclination angle of the swash plate 23 decreases, the dead volume of the first compression chamber 20a increases. The dead volume of the first compression chamber 20a refers to the clearance between the double-headed piston 25 and the first valve-port formation body 16. In the second compression chamber 20b, the discharge stroke is performed without drastically increasing the dead volume. As the inclination angle of the swash plate 23 decreases from the maximum inclination angle θmax, the dead volume of the first compression chamber 20a increases. Thus, when the first compression chamber 20a is in the suction stroke, the re-expansion time is prolonged for decreasing the pressure of the first compression chamber 20a to the suction pressure. This increases the force from the double-headed piston 25 acting on the swash plate 23 to decrease the inclination angle of the swash plate 23.
As the inclination angle of the swash plate 23 decreases to a predetermined inclination angle θx, the dead volume of the first compression chamber 20a becomes a predetermined size. Here, the pressure of the first compression chamber 20a does not reach the discharge pressure. Thus, refrigerant gas is no longer discharged from the first compression chamber 20a. As the inclination angle of the swash plate 23 decreases from the predetermined inclination angle θx to the minimum inclination angle θmin, refrigerant gas is neither discharged nor drawn in, and the compression and expansion of refrigerant gas is repeated. This decreases the force that presses the double-headed piston 25 with the pressure of the first compression chamber 20a which, in turn, decreases the force from the double-headed piston 25 that acts on the swash plate 23 to decrease the inclination angle of the swash plate 23.
In
As the inclination angle of the swash plate 23 changes from the predetermined inclination angle θx to the minimum inclination angle θmin, when the inclination angle of the swash plate 23 is the predetermined inclination angle θx, due to the re-expansion of the refrigerant gas in the first compression chamber 20a, the force from the double-headed piston 25 that acts on the swash plate 23 to decrease the inclination angle of the swash plate 23 is the greatest.
More specifically, when the inclination angle of the swash plate 23 is the predetermined inclination angle θx, the resultant force of the compression reaction forces P1 and P2 from the double-headed piston 25 acting on the swash plate 23 and the force generated by re-expansion of the refrigerant gas in the first compression chamber 20a is the greatest.
As the inclination angle of the swash plate 23 increases from the predetermined inclination angle θx to the maximum inclination angle θmax, the dead volume of the first compression chamber 20a decreases. This decreases the force generated by the re-expansion of the refrigerant gas in the first compression chamber 20a.
The pressure of the control pressure chamber 35 that maintains the inclination angle of the swash plate 23 is the greatest when the inclination angle of the swash plate 23 is the predetermined inclination angle θx. As the inclination angle of the swash plate 23 increases from the predetermined inclination angle θx to the maximum inclination angle θmax, the pressure of the control pressure chamber 35 decreases (condition of point P to point Q in broken line L1). As a result, in the prior art, the pressure of the control pressure chamber 35 required to increase the inclination angle of the swash plate 23 from the predetermined inclination angle θx to the maximum inclination angle θmax and the pressure of the control pressure chamber 35 required to increase the inclination angle of the swash plate 23 from the minimum inclination angle θmin to the predetermined inclination angle θx take the same value and exist in range Z1. Thus, it is difficult to accurately control the inclination angle of the swash plate 23.
As shown in
Accordingly, in addition to advantages (1) and (2), the third embodiment has the advantages described below.
(6) The sloped angle of the guide surface 31c relative to the axis L of the rotation shaft 21 differs between a front position and a rear position on the guide surface 31c. Thus, the inclination angle of the swash plate 23 changes in accordance with the sloped angle of the guide surface 31c. The sloped angle of the guide surface 31c relative to the axis of the rotation shaft 21 is varied to receive force from the double-headed piston 25 acting on the swash plate 23 to decrease the inclination angle of the swash plate 23. This decreases the force from the double-headed piston 25 that acts on the swash plate 23 to decrease the inclination angle of the swash plate 23. Thus, the pressure of the control pressure chamber 35 only needs to be raised to increase the inclination angle of the swash plate 23 from the minimum inclination angle θmin to the maximum inclination angle θmax.
(7) In the third embodiment, the shape of the guide surface 31c allows the axial position of the swash plate 23 to be changed. Thus, even when the inclination angle of the swash plate 23 is changed, depending on the shape of the guide surface 31c, the dead volume of the second compression chamber 20b may be kept fixed. In other words, the dead volume may be adjusted by setting a suitable shape for the guide surface 31c.
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 guide surface 44 in the first and third embodiments may be changed to the slope 44a of the second embodiment. The guide surface 31c of the first and second embodiments may be changed to the guide surface 31c of the third embodiment.
In each of the above embodiments, the abutment pin 43 may be guided by the guide surface 44 so that the center O of the swash plate 23 and the axis of the rotation shaft 21 coincide with each other when the swash plate 23 is located at the position corresponding to the maximum inclination angle θmax and the swash plate 23 is located at the position corresponding to the minimum inclination angle θmin.
In each of the above embodiments, the left side, right side, upper side, and lower side in the drawings may be changed when necessary.
In each of the above embodiments, the upper end of the swash plate 23 is located at a position that is the farthest from the axis in the upper half of the swash plate 23. However, the position that is the farthest from the axis in the upper half of the swash plate 23 does not have to be the upper end of the swash plate 23. Further, the lower end of the swash plate 23 is located at a position that is the farthest from the axis in the lower half of the swash plate 23. However, the position that is the farthest from the axis in the lower half of the swash plate 23 does not have to be the lower end of the swash plate 23.
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.
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