JP2003328933A - Piston type variable displacement compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston type variable displacement compressor having enhanced durability and miniaturization of the device, excellent responsiveness, and controlling efficiency. <P>SOLUTION: This piston type variable displacement compressor is provided with: a driving shaft; a plurality of first cylinder bores arranged along a circumference direction of the driving shaft; a first piston movably provided in the first cylinder bore; a tilting angle mechanism placed in a crank chamber, converting rotation movement of the driving shaft to reciprocating movement of the first piston, and adjusting the stroke quantity of the first piston by varying a tilting angle; a second cylinder bore provided in correspondence with the first cylinder bore so as to fasten the tilting angle mechanism; and a second piston integrally formed with the first piston, interlocking with the reciprocating movement of the first piston and reciprocating in the second cylinder bore. An intermediate pressure chamber is provided with communicates with the crank chamber through a space for fitting the second cylinder bore and the second piston. An internal pressure of the intermediate pressure chamber is set to be higher than an internal pressure of the crank chamber. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner.
For piston type variable displacement compressor used in refrigeration cycle
In particular, refrigeration cycle using carbon dioxide as a refrigerant
(Hereinafter, CO₂ Sometimes called a cycle. )As
Refrigeration in which the maximum pressure in the cycle exceeds the critical pressure of the refrigerant
The present invention relates to a piston type variable displacement compressor most suitable for a cycle.

[0002]

2. Description of the Related Art A compressor having a plurality of cylinder bores around a drive shaft and a piston reciprocating in the cylinder bores has been well known. In such a compressor, for example, by engaging a piston with a swash plate that rotates integrally with the drive shaft, the rotational movement of the drive shaft is converted into reciprocating movement of the piston, and the fluid reciprocating in the cylinder bore causes fluid ( For example, the refrigerant is compressed. Further, the compression reaction force (pressure of the fluid that pushes the piston back in the anti-compression direction) applied to the drive shaft via the swash plate during compression is absorbed by the thrust bearing that rotatably supports the drive shaft. It is like this.

However, in recent years, a CO ₂ cycle in which carbon dioxide (CO ₂ ) is used as a refrigerant has been proposed in response to a request for defluorogenation, but in the CO ₂ cycle, the refrigerant CO ₂ exceeds a critical pressure. Therefore, the load applied to the thrust bearing is significantly increased. For this reason,
If the conventional compressor is applied to the CO ₂ cycle as it is, the durability of the thrust bearing and eventually the durability of the compressor may be deteriorated. On the other hand, using a large thrust bearing with a large allowable load may lead to an increase in size of the compressor.

Therefore, for example, a proposal as shown in FIG. 15 has been made (Japanese Patent Laid-Open No. 2001-304109).
In FIG. 15, reference numeral 100 denotes a swash plate compressor.
The swash plate compressor 100 has a cylinder block 101. A front housing 102 and a rear housing 103 are joined to the cylinder block 101. A crank chamber 104 is formed between the cylinder block 101 and the rear housing 103. In the crank chamber 104, a swash plate 106 that is rotatable integrally with the drive shaft 105 is provided. Shoe 107 on swash plate 106
A plurality of pistons 109 are engaged with each other. The piston 109 is adapted to reciprocate in the cylinder bore 108 provided in the circumferential direction of the cylinder block 101 in the left-right direction in FIG.

The drive shaft 105 is a cylinder block 101.
Is rotatably supported by a radial bearing 110 provided on the rear housing 103 and a radial bearing 111 provided on the rear housing 103. One end of the drive shaft 105 projects outward from the front housing 102, and a power transmission mechanism 113 that transmits the power from the engine 112 to the drive shaft 105 is connected to one end of the drive shaft 105. The other end of the drive shaft 105 is inserted into a recess 114 provided in the rear housing 103. A passage 115 is formed at the bottom of the recess 114 to apply pressure from a discharge chamber, which will be described later, to the end surface of the drive shaft 105.

A valve plate 116 is provided between the cylinder block 101 and the front housing 102. Further, the inside of the front housing 102 is partitioned by a wall 117 into a suction chamber 118 and a discharge chamber 119. Discharge chamber 1
19 is communicated with the end face side of the drive shaft 105 via the passage 120, the muffler 121, the passage 122, and the passage 115, and the pressure of the discharge chamber 119 is applied to the end face of the drive shaft 105. Also, the passage 122 and the passage 115
A pressure control valve 123 is provided between and.

In the heat exchanger 100 as described above,
When the driving force from the engine 112 is transmitted to the drive shaft 105 and the swash plate 106 rotates, the piston 109 connected to the swash plate 106 reciprocates in the cylinder bore 108 to compress the refrigerant (CO ₂ ) and discharge chamber 119. It is designed to be discharged inside. Further, the compression reaction force applied from the piston 108 to the drive shaft 105 at the time of compressing the refrigerant is transmitted to the thrust bearing 126 via the hinge mechanism 124 and the lug plate 125 as the tilt angle control means of the swash plate 106, and is driven by the thrust bearing 126. The load on the shaft 105 can be received. Therefore, in the compressor as described above, an excessive load is not applied to the thrust bearing 126, so that the durability of the thrust bearing 126 and the durability of the compressor 100 are improved.

Further, the discharge chamber 1 is provided on the end face of the drive shaft 105.
Since the pressure acts from 19 against the compression reaction force,
The load applied to the thrust bearing 126 is reduced. Further, a pressure control valve 123 is provided between the passage 122 and the passage 115, and the pressure control valve 123 is provided.
Is opened and closed based on a signal from the control means 127. The control means 127 uses the passenger compartment temperature sensor 12
8. Based on the passenger compartment temperature setting device 129, the pressure control valve 127
Open and close. For example, when the vehicle compartment temperature detected by the sensor 128 becomes higher than the temperature of the setter 129, the opening degree of the pressure control valve 123 is throttled based on the signal from the control means 127. As a result, from the discharge chamber 119 to the passage 109,
Since the pressure applied to the crank chamber 104 through the muffler portion 121 and the like is reduced, the inclination angle of the swash plate 106 is increased, the stroke amount of the piston 109 is increased, and the discharge capacity is also increased.

Further, in the compressor 100 as described above, the shaft sealing device 130 is provided in the suction chamber 118. The suction chamber 118 is the lowest pressure region in the compressor. Therefore, the durability and reliability of the shaft sealing device can be improved as compared with the conventional compressor in which the shaft sealing device is arranged in the crank chamber whose pressure is higher than that of the suction chamber 118. That is, a pressure corresponding to the difference between the external pressure and the internal pressure of the compressor acts on the shaft sealing device, but the pressure difference between the low pressure suction chamber and the high pressure crank chamber becomes smaller. Therefore, since the load applied to the shaft sealing device is reduced, the durability of the shaft sealing device,
The reliability can be improved.

[0010]

However, in the above-described compressor 100, since the inclination angle of the swash plate 106 is changed by adjusting the pressure in the crank chamber 104, the responsiveness, Controllability may be significantly reduced. That is, the crank chamber 104 has the swash plate 1 inside.
Since it is necessary to house the 06 and the hinge mechanism 124, etc., it is necessary to set the space in a large space as necessary, and a method of adjusting the internal pressure of such a large space and changing the inclination angle of the swash plate 106 is responsive. Controllability may decrease.
In particular, in the CO ₂ cycle using high temperature and high pressure CO ₂ as a fluid, the response may be significantly delayed.

Further, in the compressor 100 as described above, when a compression reaction force is applied to the piston 109, the piston 109 may hit the inner wall of the cylinder bore 108 and the inner wall and / or the piston 109 may be worn.
When wear occurs, the outer surface of the piston 109 and the cylinder bore 1
Since the clearance between 08 increases, the compression efficiency may decrease.

An object of the present invention is, in a piston type variable displacement compressor used for a CO ₂ cycle, improving the responsiveness and controllability to changes in the discharge capacity of a fluid, and at the same time reducing the load applied to a thrust bearing. Accordingly, it is an object of the present invention to provide a piston type variable displacement compressor capable of improving the reliability and durability of the thrust bearing and eventually the device.

[0013]

In order to solve the above problems, a piston type variable displacement compressor according to the present invention comprises a drive shaft,
A plurality of first cylinder bores arranged in the circumferential direction of the drive shaft, a first piston movably provided in the first cylinder bore, and a rotary motion of the drive shaft provided in a crank chamber. A tilt mechanism that converts the reciprocating motion of the first piston and adjusts the stroke amount of the first piston by changing the tilt angle; and a tilt mechanism that is provided to correspond to the first cylinder bore across the tilt mechanism. The second cylinder bore is integrally formed with the first piston.
In a piston type variable displacement compressor having a second piston that reciprocates in the second cylinder bore in conjunction with the reciprocating movement of the piston of the second cylinder bore, through a fitting gap between the second cylinder bore and the second piston. And an internal pressure chamber communicating with the crank chamber is provided, and the internal pressure of the intermediate pressure chamber is set to be higher than the internal pressure of the crank chamber.

The end surface of the drive shaft may be exposed to the intermediate pressure chamber.

It is preferable that the intermediate pressure chamber and the discharge chamber are communicated with each other through a communication passage having a pressure control valve in the middle thereof.

It is preferable that the communication passage is provided with a throttle portion for adjusting the flow rate of the fluid. The narrowed portion can be formed, for example, by making a part of the passage have a small diameter.

The cross-sectional area of the second piston is preferably the same as or smaller than the cross-sectional area of the first piston. When the cross-sectional area of the second piston becomes larger than the cross-sectional area of the first piston, the force applied from the intermediate pressure chamber side to the end face of the second piston, that is, the force against the compression reaction force of the first piston. Is too large, the movement of the first piston may be hindered and the discharge capacity may be reduced. The clearance between the outer peripheral surface of the second piston and the inner wall of the second cylinder bore is preferably larger than the clearance between the outer peripheral surface of the first piston and the inner wall of the first cylinder bore. If both clearances have the above relationship, the intermediate pressure chamber and the crank chamber can be surely communicated with each other. Further, workability in inserting the integrally formed first and second pistons into the respective cylinder bores can be improved.

It is preferable that the internal pressure of the crank chamber and the internal pressure of the suction chamber are substantially equal. That is, in the present invention, the tilt angle of the tilt mechanism is not changed by adjusting the internal pressure of the crank chamber as in the conventional device, but the internal pressure of the intermediate pressure chamber is adjusted and the difference from the crank chamber is adjusted as described later. This is done by using pressure. Therefore, the internal pressure of the crank chamber can be set to be substantially equal to the internal pressure of the suction chamber (that is, atmospheric pressure). Therefore, the reliability and durability of the shaft sealing device that seals between the drive shaft and the crank chamber can be improved together.

In the piston type variable displacement compressor according to the present invention, the fluid in the intermediate pressure chamber is supplied into the crank chamber through the fitting gap between the second piston and the second cylinder bore. That is, each second cylinder bore is configured to communicate with each other via the intermediate pressure chamber. Further, since the intermediate pressure chamber is communicated with the discharge chamber via the passage having the throttle portion in the middle, each second cylinder bore is communicated with the passage (intermediate pressure chamber) having a substantially throttle function. Therefore, as the fluid flows from the intermediate pressure chamber side into the second cylinder bore, the lubricating oil mixed in the fluid also flows into the second cylinder bore. However, since the lubricating oil is less likely to flow than the fluid, it is likely to accumulate in the second cylinder bore. In particular, as the discharge capacity increases, that is, as the rotational speed of the compressor increases, the amount of lubricating oil accumulated in the second cylinder bore increases. The second reciprocating motion in the second cylinder bore when the lubricating oil is accumulated in the second cylinder bore
The resistance of the piston increases. Further, the resistance increases as the amount of fitting between the second piston and the second cylinder bore increases, that is, the inclination angle of the swash plate increases. Therefore, when the number of rotations of the compressor is high and the tilt angle of the swash plate is large, the force for pushing the second piston back to the first piston side is large, so that the tilt angle of the swash plate is rapidly reduced. It is possible to improve the responsiveness when shifting to the capacity control operation. Further, in the compressor of the present invention, as described above, the force against the compression reaction force of the first piston applied to the second piston increases as the discharge capacity increases, so that the inside of the compressor is abnormal due to some cause. When the pressure becomes high, the tilt angle of the swash plate can be quickly reduced. That is, since the compressor of the present invention is provided with a self-control function, the compressor can be protected.

When the inclination angle of the swash plate is large and the number of revolutions of the compressor is small, or when the number of revolutions of the compressor is large,
Moreover, when the inclination angle of the swash plate is small, the discharge capacity is not so large, or the fitting amount of the second piston is small, so the resistance received by the second piston is small. Therefore, the inclination angle of the swash plate is less likely to be reduced, and the desired cooling requirement can be maintained.

Further, since the energy compressed by the second piston and stored in the gas presses the second piston during the expansion stroke of the second piston, that is, assists the compression of the first piston, No energy loss. Note that when the compressor speed is high or the swash plate tilt angle is large, the stored energy is also used to assist the compression of the first piston, but the tilt angle of the swash plate is mainly changed. Used when you want to.

Further, as described above, the lubricating oil mixed in the fluid flows from the intermediate pressure chamber to the crank chamber through the fitting gap between the second piston and the second cylinder bore. In other words, in the compressor according to the present invention, the gap functions as an extraction passage for supplying the lubricating oil into the crank chamber, so that it is not necessary to separately form an extraction passage. However, for the purpose of increasing the amount of bleed air to the crank chamber, a separate bleed passage may be formed by separately forming a communication passage having a throttle function that connects the intermediate pressure chamber and the crank chamber.
Further, in order to improve the bleeding property, it is necessary to secure a certain amount of oil sealed in the compressor. For this reason,
The intermediate pressure chamber is preferably filled with lubricating oil when the compressor is stopped.

The tilting mechanism is not particularly limited, but may be composed of, for example, one having a swash plate that can rotate integrally with the drive shaft. Further, the tilting mechanism may be composed of one having a swash ring that can rotate integrally with the drive shaft.

In the piston type variable displacement compressor as described above, an intermediate pressure chamber having an internal pressure higher than that of the crank chamber is provided, and the intermediate pressure chamber has a fitting gap between the second cylinder bore and the second piston. Since the internal pressure of the intermediate pressure chamber is changed according to the cooling load, the internal pressure between the intermediate pressure chamber and the crank chamber can be imparted with an appropriate differential pressure. The discharge angle is controlled by changing the inclination angle of the swash ring in the room. The intermediate pressure chamber does not have to be as wide as the crank chamber that houses the tilt mechanism, but can be configured as a relatively narrow space, so that the internal pressure can be changed quickly to change the tilt angle of the swash ring, etc. can do. Therefore, the responsiveness and controllability of the compressor can be improved.

The outflow amount of the fluid from the intermediate pressure chamber to the crank chamber side can be adjusted by the fitting amount of the second piston and the second cylinder bore (that is, the moving amount of the second piston). For example, when the inclination angle of the swash ring becomes large, the amount of fitting becomes large and it becomes difficult for the fluid to flow out from the intermediate pressure chamber to the crank chamber side, and the internal pressure of the intermediate pressure chamber becomes high. Therefore, the force acting on the end face of the second piston from the side of the intermediate pressure chamber increases, so that when the inclination angle of the swash ring is reduced due to a reduction in cooling demand or the like, the inclination angle of the swash ring can be quickly reduced. . On the other hand, when the tilt angle of the swash ring becomes smaller, the amount of fitting becomes smaller, so that the fluid easily flows out from the intermediate pressure chamber to the crank chamber side, and the internal pressure of the intermediate pressure chamber becomes low. For this reason, the pressure from the intermediate pressure chamber to the end surface of the second piston decreases, so that when the tilt angle of the swash ring is increased due to an increase in cooling demand or the like, the tilt angle of the swash ring can be rapidly increased.

That is, since the inclination angle of the swash ring can be changed quickly and easily, stable capacity control can be realized even when the swash ring is operated under high temperature and high pressure such as CO ₂ cycle.

Further, in the present invention, since the tilt angle of the swash ring is changed by adjusting the internal pressure of the intermediate pressure chamber, it is not necessary to secure the airtightness in the crank chamber as in the conventional compressor. Therefore, the crank chamber and the suction chamber may communicate with each other, and the internal pressures thereof can be set to be substantially equal. Therefore, the temperature rise in the crank chamber can be prevented, and the constituent members of the tilting mechanism such as the shoe and the pivot can be sufficiently cooled. Therefore, the durability of the tilt mechanism can be improved. Also, since it is not necessary to use high heat resistant material for each of these members,
Material costs can also be reduced. Moreover, since high pressure resistance is not required, the wall thickness around the crank chamber of the cylinder block (in the radial direction) can be reduced,
The weight and size of the compressor can be promoted.

Further, in the piston type variable displacement compressor as described above, since the crank chamber and the intermediate pressure chamber are communicated with each other and the intermediate pressure chamber is communicated with the discharge chamber, the lubricant discharged together with the fluid is lubricated. The oil is again fed into the crank chamber via the intermediate pressure chamber. Further, the internal pressure of the crank chamber is lower than the internal pressure of the intermediate pressure chamber and is substantially the same as that of the suction chamber, so that the lubricating oil easily flows into the crank chamber and is difficult to flow out. Therefore, a sufficient lubricating effect can be obtained even if the amount of lubricating oil to be enclosed is small. Further, if the amount of lubricating oil to be enclosed can be reduced, the release of lubricating oil into the CO ₂ cycle can be suppressed. For example, the heat exchange performance can be improved by retaining the lubricating oil in the heat exchanger. It is possible to prevent such inconvenience from being reduced.

Further, since the crank chamber can be operated at a lower temperature and lower pressure than the conventional compressor, the compatibility of the lubricating oil with the refrigerant is lowered. Therefore, the lubricating oil is less likely to be diluted,
Since it is possible to sufficiently secure the oil film thickness in the sliding portion and the like, it is possible to further improve the durability of the tilting mechanism and the like installed in the crank chamber.

The refrigerant collected in the crank chamber is
Since it flows into the crank chamber through the narrow fitting gap between the second piston and the second cylinder bore, it rapidly expands in the crank chamber. Since the temperature of the refrigerant decreases due to the expansion, the crank chamber is also cooled at the same time.

Further, in the piston type variable displacement compressor as described above, since the internal pressure of the intermediate pressure chamber can be adjusted according to the compression reaction force applied to the first piston, the compression applied to the first piston When the reaction force increases, the internal pressure of the intermediate pressure chamber can be increased to increase the force against the compression reaction force acting on the end faces of the second piston and the drive shaft. Therefore, the durability of the thrust bearing can be improved. Further, since the load on the drive shaft and the thrust bearing can be reduced by reducing the compression reaction force, it is possible to reduce the power required for operating the compressor. In particular, the effect can be more exerted during the off operation of the clutchless type compressor, that is, during the minimum capacity operation.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a piston type variable displacement compressor of the present invention will be described below with reference to the drawings. 1 to 3 show a piston type variable displacement compressor according to a first embodiment of the present invention. In the figure, 1 indicates a piston type variable displacement compressor. In addition, in the following embodiments, the case where the compressor 1 is applied to a CO ₂ cycle in which CO ₂ is used as a refrigerant is shown.
The compressor 1 has a housing 2 and the housing 2
Is composed of four members including a front housing 3, a first cylinder block 4, a second cylinder block 5, and a rear housing 6. These members can be made of aluminum.

An intake valve 7, a discharge valve 8 and a valve plate 9 are interposed between the front housing 3 and the first cylinder block 4. A crank chamber 10 is formed in an area defined by the first cylinder block 4, the second cylinder block 5, and the rear housing 6. An intermediate pressure chamber 11 is provided in the area defined by the second cylinder block 5 and the rear housing 6.

A drive shaft 12 is inserted in the housing 2. One end of the drive shaft 12 projects from the front housing 3 to the outside, and an electromagnetic clutch 13 capable of intermittently transmitting a driving force from a vehicle engine (not shown) is connected to the one end. Further, the other end surface 14 of the drive shaft 12 is exposed to the intermediate pressure chamber 11. A seal member 56 is interposed at the other end of the drive shaft 12.

The drive shaft 12 is rotatably supported by a radial bearing 15 provided on the first cylinder block 4 and a radial bearing 16 provided on the second cylinder block 5. A thrust bearing 17 is provided on the second cylinder block 5. The thrust bearing 17 resists the compression reaction force applied to the first piston 19 described later and resists the drive shaft 15
Is rotatably supported.

The first cylinder block 4 is provided with a plurality of first cylinder bores 18 in the circumferential direction of the drive shaft 12. A first piston 19 is reciprocally provided in each first cylinder bore 18. First piston 1
9 is connected to the swash ring 21 of the tilt mechanism 20. The drive shaft 12 is inserted through the swash ring 21. The drive shaft 12 is provided on the inner circumference of the swash ring 21.
The pivot 22 fixed to is engaged. The swash ring 21 can rotate integrally with the drive shaft 12 with an inclination angle. On the drive shaft 12, the shaft 1
There is provided a sleeve 23 that can move above 2, and a spring 24 that biases the sleeve 23 toward the anti-thrust bearing side.
Then, the first piston 19 is replaced by the first cylinder bore 18
The compression reaction force applied to the first piston 19 when the fluid (CO ₂ ) is compressed therein is received by the spring 24 and the thrust bearing 17.

The second cylinder block 5 includes a tilting mechanism 2
2nd corresponding to each 1st cylinder bore 18 across 0
Cylinder bore 25 is provided. A second piston 26 integrally formed with the first piston 19 is provided in the second cylinder bore 25 so as to be able to reciprocate.
Therefore, the second piston 26 is replaced by the first piston 19
It reciprocates in the second cylinder bore 25 in conjunction with the reciprocating motion of the. Further, the second cylinder bore 25 is opened to the intermediate pressure chamber 11. For this reason, the intermediate pressure chamber 11 and the crank chamber 10 are communicated with each other through a slight clearance in which the second cylinder bore 25 and the second piston 26 are fitted with each other. It should be noted that the above-mentioned gap is also generated between the first cylinder bore 18 and the first piston 19, but in the present embodiment, the fitting gap between the second cylinder bore 25 and the second piston 26 is the first gap. It is set so as to be slightly larger than the fitting gap between the cylinder bore 18 and the first piston 19. With such a dimensional relationship, the intermediate pressure chamber 11 to the crank chamber 1
The fluid can smoothly flow into the 0 side. In addition, the workability of assembling can be improved.

A suction chamber 27 and a discharge chamber 28 are formed between the first cylinder block 4 and the front housing 3 as shown in FIG. The suction chamber 27 is provided with a suction port 29. From the suction port 29 to the suction chamber 2
The fluid that has flowed into the inside 7 flows into the first cylinder bore 18 from the suction hole 30, is compressed in the bore 18, and is then discharged from the discharge hole 31 into the discharge chamber 28. In FIG. 2, 32 is the front housing 3.
2 shows a bolt that fastens the first cylinder block 4 to each other.

In the present embodiment, the discharge chamber 28 and the intermediate pressure chamber 11 are communicated with each other via the passage 33. The passage 33 includes a passage 34 provided in the first cylinder block 4, a passage 35 provided in the second cylinder block 5, and a passage 36 provided in the rear housing 6.
It consists of and. The diameter of the passage 35 is smaller than that of the passage 34 on the discharge chamber side, and the fluid flowing out from the discharge chamber 28 is narrowed by the passage 35. That is, the passage 35 functions as a throttle.

At the outlet of the communication passage 36, the intermediate pressure chamber 11
There is provided a pressure control valve 37 capable of adjusting the internal pressure of the.
The pressure control valve 37 is an electromagnetic valve as shown in FIG. The pressure control valve 37 has valve chambers 38 and 39. A communication passage 36 is opened in the valve chamber 38. Also,
The valve chambers 38 and 39 are communicated with each other via a valve hole 40. The valve hole 40 is provided with a spherical valve body 41. The solenoid 42 includes a fixed iron core 43, a movable iron core 44, and a coil 4.
5 and 5. A spring 46 is interposed between the fixed iron core 43 and the movable iron core 44, and the movable iron core 44 is biased by the spring 46 toward the side opposite to the fixed iron core. Further, the movable iron core 44 is provided with a rod 47. For this reason,
In a normal state, the valve body 4 is urged by the urging force of the spring 46.
Since No. 1 is located in the direction of opening the valve hole 47 (on the left side in FIG. 3), the fluid flowing into the valve chamber 38 flows into the valve chamber 39 and further flows out into the intermediate pressure chamber 11.

On the other hand, when the solenoid 42 is excited, an attractive force (electromagnetic force) is generated between the iron cores 43 and 44, so that the iron core 44 moves toward the iron core 43 side against the urging force of the spring 46. . Therefore, the valve body 41 moves in the direction to close the valve hole 40 by the biasing force of the barb 48, so that the inflow of the fluid into the intermediate pressure chamber 11 is blocked.

The pressure control valve 37 can be controlled by a control computer (not shown). For example, the passenger compartment temperature detected by the passenger compartment temperature sensor, the set passenger compartment temperature,
Based on an external signal such as the number of revolutions of the engine, the control computer commands an input current value to a drive circuit (not shown) of the control valve 37 to excite the coil 45 of the valve 37 to control the opening and closing of the valve 37. ing. Based on such control action, in the present embodiment, the internal pressure of the intermediate pressure chamber 11 is always higher than the internal pressure of the crank chamber 10.

A shaft sealing device 49 for the drive shaft 12 is provided in the suction chamber 27. This prevents fluid from leaking from the suction chamber 27. Shaft seal device 49
As shown in FIG. 4, a ring 50 made of carbon, which is fitted and fixed to the front housing 3, and a sliding contact ring 52 made of carbon, which slidably contacts the ring 50 integrally rotatably attached to the drive shaft 12 through the O-ring 51. It has and. Ring 5
0 is loosely fitted to the drive shaft 12. Further, an O-ring 53 is interposed between the ring 50 and the front housing 3. A groove 54 is provided on the outer peripheral portion of the sliding contact ring 52. A support ring 55 that is integrally rotatable with the shaft 12 is inserted into the groove 54. A spring 70 that biases the sliding contact ring 52 toward the ring 50 is provided in the support ring 55.

In the piston type variable displacement compressor according to the present embodiment, the intermediate pressure chamber 11 having an internal pressure higher than that of the crank chamber 10 is provided, and the intermediate pressure chamber 11 includes the second cylinder bore 25 and the second piston. Since the internal pressure of the intermediate pressure chamber 11 is changed according to the cooling load or the like, the compression applied to the end face of the second piston 26 is communicated with the crank chamber 10 through a fitting gap with the second piston 26. The force that resists the reaction force changes. That is, the tilt angle of the swash ring 21 is changed by the difference between the force acting in the direction against the compression reaction force and the compression reaction force. Therefore, the internal pressure of the intermediate pressure chamber 11, which can be configured as a relatively narrow space, can be quickly changed to change the inclination angle of the swash ring 21, so that the responsiveness and controllability of the compressor 1 can be improved. it can.

Further, from the intermediate pressure chamber 11 to the crank chamber 10
The outflow amount of the fluid to the side is the amount of fitting between the second piston 20 and the second cylinder bore 26 (that is, the second piston 2
6 movement amount). For example, when the tilt angle of the swash ring 21 becomes large, the amount of fitting becomes large, the flow amount of fluid from the intermediate pressure chamber 11 to the crank chamber 10 side is limited, and the internal pressure of the intermediate pressure chamber 11 becomes high.
Therefore, the intermediate pressure chamber 1 to the end surface of the second piston 26
Since the force acting from the 1st side increases, when the inclination angle of the swash ring 21 is reduced due to a reduction in the cooling demand or the like,
The tilt angle of the swash ring 21 can be quickly reduced. On the other hand, when the tilt angle of the swash ring 21 becomes small, the amount of fitting becomes small, so that the amount of fluid flowing out from the intermediate pressure chamber 11 to the crank chamber 10 side increases and the internal pressure of the intermediate pressure chamber 11 becomes low. For this reason, the pressure from the intermediate pressure chamber 11 to the end surface of the second piston 26 decreases, so that when the tilt angle of the swash ring 21 is increased due to an increase in cooling demand or the like, the tilt angle of the swash ring 21 is rapidly increased. it can.

That is, since the tilt angle of the swash ring 21 can be changed quickly and easily, CO ₂
Stable capacity control can be realized even when operated under high temperature and high pressure like a cycle.

Further, in the present invention, since the inclination angle of the swash ring 21 is changed by adjusting the internal pressure of the intermediate pressure chamber 11, it is necessary to ensure the airtightness in the crank chamber 10 as in the conventional compressor. There is no. Therefore, the crank chamber 10 and the suction chamber 27 may be communicated with each other, and their internal pressures can be set to be substantially equal. Therefore, the temperature rise in the crank chamber 10 can be prevented,
It is possible to sufficiently cool the constituent members of the tilting mechanism 20, such as the connecting portion between the pivot 22 and the swash ring 21.
Therefore, the durability of the tilt mechanism 20 can be improved. Further, since it is not necessary to use a high heat resistant material for each of these members, the material cost can be reduced.

The piston type variable displacement compressor 1 as described above
In the above, since the crank chamber 10 and the intermediate pressure chamber 11 are communicated with each other and the intermediate pressure chamber 11 is communicated with the discharge chamber 28, the lubricating oil discharged together with the fluid is again
It is supplied into the crank chamber 10 via the intermediate pressure chamber 11. Further, the internal pressure of the crank chamber 10 is lower than the internal pressure of the intermediate pressure chamber 11 and is substantially equal to that of the suction chamber 27, so that the lubricating oil easily flows into the crank chamber 10 and does not easily flow out. Has become. Therefore, a sufficient lubricating effect can be obtained even if the amount of lubricating oil to be enclosed is small. Further, if the amount of lubricating oil to be filled can be reduced, it is possible to suppress the release of lubricating oil into the CO ₂ cycle, so that the lubricating oil stays in a heat exchanger (not shown), for example. It is possible to prevent such an inconvenience that the exchange performance is deteriorated.

Further, since the temperature inside the crank chamber 10 is low and the pressure is low, the compatibility of the lubricating oil with the refrigerant is lowered. Therefore, the lubricating oil is less likely to be diluted, and the oil film thickness at each sliding portion or the like can be sufficiently secured, so that the durability of the tilt mechanism 20 installed in the crank chamber 10 can be further improved. .

Further, the refrigerant recovered in the crank chamber 10 flows into the crank chamber 10 through the narrow fitting gap between the second piston 26 and the second cylinder bore 25, so that the crank chamber 10 is cooled. It will expand rapidly at. Since the temperature of the refrigerant decreases due to the expansion, the inside of the crank chamber 10 is also cooled at the same time.

In the piston type variable displacement compressor as described above, the internal pressure of the intermediate pressure chamber 11 can be adjusted according to the compression reaction force applied to the first piston 19, so that the first piston 19 When the compression reaction force applied to is increased, the internal pressure of the intermediate pressure chamber 11 can be increased and the force against the compression reaction force acting on the end faces of the second piston 26 and the drive shaft 12 can be increased. Therefore, the durability of the thrust bearing 17 can be improved.

Further, in the present embodiment, the shaft sealing device 4
Since 9 is provided in the suction chamber 27 having a low internal pressure, a compact compressor can be used as compared with the conventional compressor.
Therefore, cost reduction of the compressor can be further promoted.

Further, in this embodiment, as described above, the fluid in the intermediate pressure chamber 11 is supplied into the crank chamber 10 through the fitting gap between the second piston 26 and the second cylinder bore 25. To be done. That is, the second cylinder bores 25 are connected to each other via the intermediate pressure chamber 11 having the pressure control valve 37 having a throttle function. Therefore, as the fluid flows from the side of the intermediate pressure chamber 11 into the second cylinder bore 25, the lubricating oil mixed in the fluid also flows into the second cylinder bore 25. However, compared to fluid (air), the lubricating oil is likely to collect in the gap between the bore 25 and the piston 26 and in the bore 25. Especially,
When the internal pressure of the discharge chamber 28 increases with the increase of the discharge capacity, that is, the rotation speed of the compressor, the internal pressure of the intermediate pressure chamber 11 also increases, and the amount of lubricating oil flowing into the second cylinder bore 25 also increases. . When the lubricating oil collects in the second cylinder bore 25, the resistance to the second piston 26 increases. Further, the resistance increases as the fitting amount of the second piston 26 into the second cylinder bore 25 increases, that is, as the inclination angle of the swash ring 21 increases (FIG. 5). Therefore, when the number of rotations of the compressor is high and the inclination angle of the swash ring 21 is large, the force for pushing the second piston 25 back toward the first piston 19 side (the first piston 1
Since the force against the compression reaction force applied to 9 becomes large, the inclination angle of the swash ring 21 can be rapidly reduced when shifting to the capacity control operation. Therefore, the responsiveness of the compressor 1 can be improved.

When the inclination angle of the swash ring 21 is large and the rotation speed of the compressor is small, or when the rotation speed of the compressor is large and the inclination angle of the swash ring 21 is small, the discharge capacity is too large. No, or because the amount of fitting of the second piston 26 is small, the resistance received by the second piston 26 is small. Therefore, the inclination angle of the swash ring 21 is not easily reduced, and the desired cooling requirement can be maintained.

The energy stored in the gas after being compressed by the second piston 26 presses the second piston 26 during the expansion stroke of the second piston 26, that is, the compression of the first piston 19 is performed. It does not cause energy loss because it helps. If the compressor rotation speed is large or the swash plate tilt angle is large, the stored energy is
It is also used to assist the compression of the first piston 19, but is mainly used when changing the inclination angle of the swash ring 21.

Further, as described above, the lubricating oil mixed in the fluid is the second piston 26 and the second cylinder bore 25.
It flows into the crank chamber 10 from the intermediate pressure chamber 11 through the fitting gap with the. In other words, in the present invention, since the above-mentioned gap functions as an extraction passage for supplying the lubricating oil into the crank chamber 10, it is not necessary to separately form an extraction passage.

FIG. 7 shows a piston type variable displacement compressor according to the second embodiment of the present invention. In the embodiments described below, the same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, the end surface of the drive shaft 12 is not exposed to the intermediate pressure chamber 11 but exists on the crank chamber 10 side. Therefore, the sealing material 56 as in the first embodiment can be omitted.

Also in this embodiment, the inclination angle of the swash ring 21 can be rapidly changed by utilizing the pressure difference between the internal pressures of the intermediate pressure chamber 11 and the crank chamber 10 in accordance with the operation of the first embodiment. A compressor with excellent responsiveness, controllability, and durability can be realized at low cost. In addition,
In the present embodiment, the end surface 14 of the drive shaft 12 is configured so as not to be exposed in the intermediate pressure chamber 11, but the second piston 26 has a force against the compression reaction force from the intermediate pressure chamber 11. Since it works, the effect of reducing the load on the thrust bearing 17 can be sufficiently ensured.

FIG. 8 shows a piston type variable displacement compressor according to the third embodiment of the present invention. The intermediate pressure chamber 11 in the present embodiment includes a passage 57 communicating with the outlet of the pressure control valve 37, and a passage 58 communicating with the passage 57 and the second cylinder bore 25. Further, in the present embodiment, the housing 2 is
It is composed of a front housing 3, a first cylinder block 4, and a rear housing 6. For this reason, the intermediate pressure chamber 11 including the second cylinder bore 25 and the passages 57 and 58 is provided in the rear housing 6. Also,
Of the communication passages 33, a passage 35 having a throttle function is also provided in the rear housing 6.

Also in the present embodiment, the inclination angle of the thrust bearing 21 can be rapidly changed by utilizing the difference in internal pressure between the intermediate pressure chamber 11 and the crank chamber 10, so that the response and controllability are excellent. A compressor can be provided. Further, since the intermediate pressure chamber 11 is constituted by the passages 57 and 58 having a small volume, the internal pressure of the intermediate pressure chamber 11 can be changed more quickly, so that the responsiveness and the like can be further improved. In addition, downsizing of the device can be promoted. In this embodiment, since the rear housing 6 substitutes the second cylinder block 5, the number of parts can be reduced and the cost can be further reduced.

FIG. 9 shows a piston type variable displacement compressor according to a fourth embodiment of the present invention. In the present embodiment, the intermediate pressure chamber 11 has a passage 59 communicating with the outlet of the pressure control valve 37. A passage 60 communicating with one second cylinder bore 18 is connected to one end of the passage 59. Further, the other end of the passage 59 is opened to a space 61 where the end surface 14 of the drive shaft 12 is exposed. Space 61
A passage 62, which communicates the second cylinder bore 18 and the space 61, other than the passage 60 communicating therewith, is opened. The passage 62 is communicated with the second cylinder bore 18 other than the passage 60 through the passage 63. In the present embodiment, the intermediate pressure chamber 11 is formed by the passages 59, 60, 62, 63 and the space 61.

Also in this embodiment, since the tilt angle of the swash ring 21 can be changed quickly, the responsiveness,
A compressor having excellent controllability can be provided. Also,
Since the volume of the intermediate pressure chamber 11 can be reduced similarly to the third embodiment, it is possible to further improve the responsiveness while contributing to downsizing and cost reduction of the device.

FIG. 10 shows a piston type variable displacement compressor according to a fifth embodiment of the present invention. In the present embodiment, a column 64 is provided inside the intermediate pressure chamber 11. The support column 64 is formed integrally with the second cylinder block 5. Further, the inside of the second cylinder bore 25 and the intermediate pressure chamber 11 are communicated with each other through an opening portion 65 formed at the base of the support column 64 (FIG. 11).

Also in this embodiment, the differential pressure between the intermediate pressure chamber 11 and the crank chamber 10 is utilized to utilize the swash ring 2
Since the tilt angle of No. 1 can be changed quickly, the responsiveness and controllability of the device can be improved. Further, since the column 64 that joins the second cylinder block 5 and the rear housing 6 is provided in the intermediate pressure chamber 11, the pressure resistance of the intermediate pressure chamber 11 can be further improved.

FIG. 12 shows a piston type variable displacement compressor according to a sixth embodiment of the present invention. In the present embodiment, the drive shaft 1 provided on the second cylinder block 5
The second insertion portion 66 is joined to the inner wall of the rear housing 6. Therefore, in the present embodiment, the insertion portion 66
An intermediate pressure chamber 11 is formed in the circumferential direction.

Also in this embodiment, the inclination angle of the swash ring 21 can be changed quickly by utilizing the differential pressure between the intermediate pressure chamber 11 and the crank chamber 10, so that the compression with excellent responsiveness and controllability is achieved. Machine can be provided. Moreover, since the insertion portion 66 of the second cylinder block 5 is in contact with the inner wall of the rear housing 6, the pressure resistance of the intermediate pressure chamber 11 can be improved.

FIG. 13 shows a piston type variable displacement compressor according to a seventh embodiment of the present invention. In the present embodiment, the drive shaft 1 provided on the second cylinder block 5
The insertion part 66 into which the other part of 2 is inserted is the rear housing 6
It is fitted in a fitting portion 67 provided on the inner wall of the intermediate pressure chamber 11 and the intermediate pressure chamber 11 is formed around the fitting portion 67. Also in this embodiment, the inclination angle of the swash ring 21 can be rapidly changed by utilizing the differential pressure between the intermediate pressure chamber 11 and the crank chamber 10, so that a compressor excellent in responsiveness and controllability is realized. be able to.

FIG. 14 shows a piston type variable displacement compressor according to an eighth embodiment of the present invention. In the present embodiment, a communication passage 68 is provided between the crank chamber 10 and the suction chamber 27, and both chambers are in communication with each other. The compressor according to the present invention differs from the conventional compressor in the crank chamber 10
Can be set to a low temperature and a low pressure that are substantially equal to those of the suction chamber 27, but the internal pressure of the crank chamber 10 may become higher than that of the suction chamber 27 due to the entry of fluid from the intermediate pressure chamber 11. Therefore, in the present embodiment, the suction chamber 27 and the crank chamber 1
The sealing material 69 is interposed between the sealing material 69 and
Is provided to prevent the problem that a large amount of fluid from the crank chamber 10 flows in and the internal pressure of the suction chamber 27 rises.

[0069]

As described above, in the case of the piston type variable displacement compressor of the present invention, the intermediate pressure chamber is provided, and the internal pressure of the intermediate pressure chamber is adjusted, whereby the difference between the intermediate pressure chamber and the crank chamber is adjusted. Since the tilt angle of the tilt mechanism can be changed by using the pressure, the responsiveness is better than that of a conventional compressor that changes the tilt angle of the tilt mechanism by changing the internal pressure of the crank chamber.
Controllability can be improved.

Further, since the pressure inside the crank chamber can be set to a low pressure as compared with the conventional compressor, the lubricating effect of the sliding member by the lubricating oil can be improved and the durability of the device can be improved. Further, since the load on the thrust bearing can be reduced, the durability of the thrust bearing can be improved while preventing the size of the device from increasing.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a piston type variable displacement compressor according to a first embodiment of the present invention.

FIG. 2 is a II-II of the piston type variable displacement compressor of FIG.
It is sectional drawing which follows the line.

3 is a longitudinal sectional view of a pressure control valve of the piston type variable displacement compressor shown in FIG.

FIG. 4 is a vertical sectional view of a shaft sealing device of the piston type variable displacement compressor shown in FIG.

5 is a perspective view showing a fitted state of a second piston and a second cylinder bore during maximum displacement operation of the piston type variable displacement compressor of FIG. 1. FIG.

6 is a perspective view showing a fitted state of a second piston and a second cylinder bore during the minimum displacement operation of the piston type variable displacement compressor of FIG. 1. FIG.

FIG. 7 is a vertical sectional view of a piston type variable displacement compressor according to a second embodiment of the present invention.

FIG. 8 is a vertical sectional view of a piston type variable displacement compressor according to a third embodiment of the present invention.

FIG. 9 is a vertical cross-sectional view of a piston type variable displacement compressor according to a fourth embodiment of the present invention.

FIG. 10 is a vertical sectional view of a piston type variable displacement compressor according to a fifth embodiment of the present invention.

11 is a cross-sectional view of a column provided in the intermediate pressure chamber of the piston type variable displacement compressor of FIG.

FIG. 12 is a vertical sectional view of a piston type variable displacement compressor according to a sixth embodiment of the present invention.

FIG. 13 is a vertical sectional view of a piston type variable displacement compressor according to a seventh embodiment of the present invention.

FIG. 14 is a vertical sectional view of a piston type variable displacement compressor according to an eighth embodiment of the present invention.

FIG. 15 is a vertical sectional view of a conventional compressor.

[Explanation of symbols]

1 Piston type variable displacement compressor 2 housing 3 front housing 4 1st cylinder block 5 2nd cylinder block 6 rear housing 7 Inhalation valve 8 discharge valve 9 valve plate 10 crank chambers 11 Intermediate pressure chamber 12 drive shaft 13 Electromagnetic clutch 14 End face of drive shaft 15, 16 radial bearing 17 Thrust bearing 18 First cylinder bore 19 First piston 20 Tilt mechanism 21 swash ring 22 pivot 23 Sleeve 24 springs 25 Second cylinder bore 26 Second piston 27 Inhalation chamber 28 Discharge chamber 29 Inhalation port 30 suction hole 31 discharge hole 32 volts 33, 34, 35, 36, 68 Communication passage 37 Pressure control valve 38, 39 valve chamber 40 valve holes 41 valve 42 solenoid 43 Fixed iron core 44 Movable iron core 45 coils 46 spring 47 rod 48 springs 49 shaft seal device Fifty rings 51 O-ring 52 Sliding contact ring 53 O-ring 54 groove 55 Support ring 56,69 Seal material 57, 58, 59, 60, 62, 63 passages 61 space 64 props 65 openings 66 Insert 67 Fitting part 70 spring

Claims (11)

[Claims] 1. A drive shaft, a plurality of first cylinder bores arranged in a circumferential direction of the drive shaft, a first piston movably provided in the first cylinder bore, and a crank chamber. And a tilt mechanism for converting the rotary motion of the drive shaft into a reciprocating motion of the first piston and adjusting the stroke amount of the first piston by changing the tilt angle, and a first tilting mechanism sandwiching the tilting mechanism. A second cylinder bore provided corresponding to the cylinder bore; and a second piston configured integrally with the first piston to reciprocate in the second cylinder bore in conjunction with the reciprocating movement of the first piston. A piston type variable displacement compressor having a second
Is provided with an intermediate pressure chamber that communicates with the crank chamber through a fitting gap between the cylinder bore and the second piston, and the internal pressure of the intermediate pressure chamber is set higher than the internal pressure of the crank chamber. Piston type variable displacement compressor. 2. The piston type variable displacement compressor according to claim 1, wherein an end face of the drive shaft is exposed to the intermediate pressure chamber. 3. The intermediate pressure chamber and the discharge chamber communicate with each other through a passage having a pressure control valve in the middle thereof.
Or 2 piston type variable displacement compressor. 4. A piston type variable displacement compressor according to claim 3, wherein the communication passage is provided with a throttle portion for adjusting the flow rate of the fluid. 5. The piston type variable displacement compressor according to claim 1, wherein a cross-sectional area of the second piston is substantially equal to or smaller than a cross-sectional area of the first piston. . 6. The piston type variable displacement compressor according to claim 1, wherein the internal pressure of the crank chamber and the internal pressure of the suction chamber are substantially equal to each other. 7. The plurality of second cylinder bores are in communication with each other through an intermediate pressure chamber.
A piston type variable displacement compressor according to any one of 1. 8. The piston type variable displacement compressor according to claim 1, wherein the intermediate pressure chamber is filled with a lubricating oil. 9. The piston type variable displacement compressor according to claim 1, wherein the intermediate pressure chamber and the crank chamber are communicated with each other by a communication passage having a pressure reducing device in the middle thereof. 10. The piston type variable displacement compressor according to claim 1, wherein the tilting mechanism has a swash plate that is integrally rotatable with a drive shaft. 11. The piston type variable displacement compressor according to claim 1, wherein the tilting mechanism has a swash ring that can rotate integrally with a drive shaft.