JPH11241680A - Variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable displacement compressor capable of improving acceleration performance by detecting the acceleration state of an engine for a vehicle and changing discharge displacement from large capacity to small capacity. SOLUTION: A boosting passage 24 communicating a discharge chamber 13b with a crank chamber 15 is provided on a cylinder block 12 and a differential pressure valve 31 is disposed in the passage 24. A valve element 33 constituting this differential pressure valve 31 is energized to a location where the passage 24 is always closed by a spring 34. When pressure Pd within the discharge chamber 13b rapidly rises in an acceleration state of a compressor, pressure within a second pressure sensitive chamber 45 rises and thereby a spool 42 and a rod 43 open the valve element 33 against energizing force of a spring 48. Therefore, gas in the discharge chamber 13b is supplied from the boosting passage 24 to the crank chamber 15, pressure Pc within the chamber 15 is enhanced, an inclined angle of a swash plate 19 is reduced, the compressor is switched from a large capacity operation to a small capacity operation and acceleration performance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement compressor used in, for example, a vehicle air conditioner.

[0002]

2. Description of the Related Art As a conventional variable displacement compressor of this type, the following configuration is known. That is,
A crank chamber is formed inside the housing,
A drive shaft is rotatably supported. A plurality of cylinder bores are formed in a cylinder block constituting a part of the housing, and a piston is accommodated in each cylinder bore so as to be able to reciprocate. A cam plate is mounted on the drive shaft in the crank chamber so as to be integrally rotatable and swingable, and the peripheral edge of the cam plate is moored to each piston. The displacement control valve changes the pressure difference between the pressure in the crank chamber and the pressure in the cylinder bore through the piston, and changes the inclination angle of the cam plate according to the pressure difference to control the discharge capacity. It is configured.

The variable displacement compressor configured as described above is
When the air conditioner is operated by being connected to a vehicle engine via an electromagnetic clutch, the electromagnetic clutch is turned on to operate the compressor.

[0004]

In this conventional variable displacement compressor, an external drive source such as a vehicle engine is used when the cam plate is arranged at a large inclination and a compression operation with a large discharge capacity is performed. , The drive shaft may be rotated at high speed. In such a case, the compression load sharply increases, and Pv of the sliding portion in the compressor increases.
The value (the value of the product of the surface pressure between the sliding contact surfaces and the sliding speed) is greatly increased, which causes a problem that the service life of the sliding portion and, consequently, the compressor is shortened.

In order to solve the above-mentioned problem, when the accelerator is depressed to accelerate the engine of the vehicle, the parameter indicating the acceleration state during the acceleration operation, that is, the degree of increase of the engine speed, the boost of the engine, and the like. Pressure,
By detecting the opening of the accelerator, the electromagnetic clutch is turned off to stop the compressor. As a result, the temperature of the air blown out of the evaporator greatly fluctuates, and unpleasant warm warm air is blown into the passenger compartment, which causes a problem that the cooling feeling deteriorates. In addition, there is a problem that a shock of starting the compressor occurs when the electromagnetic clutch is turned on / off.

Some vehicles do not stop the operation of the compressor during the acceleration operation as described above. However, in such a case, there is a problem that the acceleration of the vehicle is deteriorated and the fuel consumption efficiency is reduced. Was.

In order to solve the above problem, a variable capacity compressor as shown in, for example, US Pat. No. 4,872,814 and the drawings has been proposed. This compressor has basically the same configuration as the above-described variable displacement compressor, and has a drive shaft provided with an on-off valve for opening and closing a pressure-up passage that connects a discharge pressure region and a crank chamber. The on-off valve is always kept in a state where the boost passage is closed, and when the rotation speed of the drive shaft becomes higher than a predetermined value, the on-off valve opens the boost passage by centrifugal force. I have. For this reason, when the rotation speed of the drive shaft exceeds a predetermined value during the compression operation with a large discharge capacity, the on-off valve is opened, and the high-pressure refrigerant gas in the discharge pressure region is introduced into the crank chamber through the pressure increasing passage. Is done. And
As the pressure in the crank chamber increases, the inclination angle of the cam plate is reduced, the discharge capacity is reduced, and the compression load is reduced.

In the above-described conventional variable displacement compressor,
When the drive shaft rotates at a high speed, the on-off valve operated by the centrifugal force is opened, and the high-temperature and high-pressure refrigerant gas in the discharge pressure region is introduced into the crank chamber through the boost passage. For this reason, the discharge capacity of the compressor remains at the minimum capacity in the high rotation region, and there has been a problem that the capacity cannot be temporarily reduced only in the acceleration state.

In addition, there has been a problem that the capacity switching mechanism operated by the centrifugal force with the increase in the rotation speed of the drive shaft is complicated, the number of parts is increased, and the manufacturing and assembling work is troublesome.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, to reliably detect the acceleration state and to switch the discharge capacity from a large capacity to a small capacity, and to perform the discharge after the end of the acceleration. An object of the present invention is to provide a variable displacement compressor that can increase the capacity and simplify the structure.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, a crank chamber is formed inside a housing, a drive shaft is rotatably supported, and a part of the housing is formed. A cylinder block is formed with a cylinder bore, and a piston is reciprocally accommodated in the cylinder bore, and a cam plate for reciprocating the piston is mounted on the drive shaft so as to be swingable, and a crank chamber is provided. In a variable displacement compressor in which a displacement of a cam plate is controlled by changing a tilt angle of a cam plate according to a first differential pressure between a pressure and a pressure in a cylinder bore through the piston, a discharge pressure region and a crank chamber are separated from each other. The pressure in the discharge pressure range during steady operation and the pressure in the middle of acceleration are set in one of the pressure increasing passage communicating with the pressure chamber and the pressure releasing passage communicating the crank chamber with the suction pressure region. When the second differential pressure with respect to the pressure in the pressure output region becomes equal to or more than a predetermined value, the first differential pressure is increased by opening the pressure increasing passage or closing the pressure releasing passage, thereby decreasing the discharge capacity, and accelerating. After the termination, a differential pressure valve is provided which operates to return the second differential pressure to a predetermined value or less and increase the discharge capacity.

According to a second aspect of the present invention, in the first aspect, the differential pressure valve is disposed in the middle of the pressure increasing passage, and is configured to control a pressure in a discharge pressure region during a steady operation and a pressure in a discharge pressure region during an acceleration. When the second differential pressure becomes equal to or higher than a predetermined value, the boosting passage is opened, and after the acceleration is completed, the second differential pressure is returned to a predetermined value or less and the boosting passage is closed.

According to a third aspect of the present invention, in the first aspect, the differential pressure valve is disposed in the middle of a pressure release passage, and a pressure in a discharge pressure region during a steady operation and a pressure in a discharge pressure region during an acceleration. When the second differential pressure with the pressure difference is equal to or more than a predetermined value, the pressure release passage is closed, and after the acceleration is completed, the second pressure difference is returned to a predetermined value or less to open the pressure release passage. I have.

According to a fourth aspect of the present invention, in the first aspect, the differential pressure valve restricts a pressure in a discharge pressure area during a steady operation on one side of the spool accommodated in the accommodation chamber so as to reciprocate. A first pressure-sensitive chamber formed on one side of the storage chamber so as to act via a passage, and a pressure-sensitive chamber formed on the other side of the storage chamber so as to apply pressure in a discharge pressure area during acceleration to the other surface of the spool. A second pressure sensing chamber, an on-off valve for opening the pressure increasing passage or closing the pressure releasing passage when the second differential pressure exceeds a predetermined value and operates the spool in an accelerated state, and the spool And a biasing means for constantly biasing the on-off valve in a direction to be closed or opened.

According to a fifth aspect of the present invention, in the fourth aspect, the spool, the on-off valve and the biasing member are formed in a storage chamber and a valve chamber formed in the cylinder block. In the invention described in claim 6, in claim 4 or 5, the throttle passage is formed so as to communicate the first pressure-sensitive chamber and the second pressure-sensitive chamber with the spool.

According to the seventh aspect of the present invention, in the fourth aspect,
In any one of the fifth and sixth aspects, the on-off valve may be pressed by an operating rod connected to the spool, and the valve may be constantly pressed to a closed position of the pressure increasing passage or an open position of the pressure releasing passage. And an urging member.

According to an eighth aspect of the present invention, in the seventh aspect, the urging member of the valve element also serves as the urging member for urging the spool. According to a ninth aspect of the present invention, in any one of the first to third aspects, the air supply passage communicating the discharge pressure region and the crank chamber, or the bleed passage communicating the crank chamber and the suction pressure region, First
A capacity control valve that changes the differential pressure according to the cooling load is provided.

According to a tenth aspect of the present invention, in the ninth aspect, the capacity control valve is disposed in the middle of the air supply passage, and the capacity control valve is used to transfer the refrigerant gas from the discharge pressure region to the crank chamber. The discharge capacity is changed by adjusting the supply amount.

According to an eleventh aspect of the present invention, in the ninth aspect, the displacement control valve is disposed in the middle of the bleed passage, and the displacement control valve extracts the refrigerant gas from the crank chamber to the suction pressure region. By adjusting the amount, the discharge capacity is changed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below in detail with reference to FIGS.

As shown in FIG. 1, a front housing 11 forming a part of the housing is joined and fixed to a front part of a cylinder block 12 also forming a part of the housing. A rear housing 13, which also forms a part of the housing, is fixedly connected to a rear portion of the cylinder block 12 via a valve plate 14. The front housing 11, the cylinder block 12, and the rear housing 13 constitute a housing of the entire compressor.

In the rear housing 13, a suction chamber 13a forming a suction pressure area and a discharge chamber 13b forming a discharge pressure area are defined. Valve plate 14
Is provided with a suction valve 14a and a discharge valve 14b. The front housing 11 and the cylinder block 1
2 form a crank chamber 15. A drive shaft 16 is rotatably supported by the front housing 11 and the cylinder block 12 via a pair of radial bearings 17 so as to penetrate through the crank chamber 15.

The rotating support 18 is provided with the drive shaft 16.
Is fitted and fixed. The swash plate 19 as a cam plate is supported by the drive shaft 16 in the crank chamber 15 so as to be slidable in the axial direction and tiltable. The swash plate 19 is connected to the rotating support 18 via a hinge mechanism 20. And the swash plate 19
The hinge mechanism 20 guides sliding movement and tilting in the axial direction, and rotates together with the drive shaft 16.

The maximum inclination angle of the swash plate 19 is determined by the stopper 19a provided on the swash plate 19 and the rotation support member 18.
Stipulated by the abutment. The minimum inclination angle of the swash plate 19 is determined by the circlip 16 b attached to the drive shaft 16.
And the contact with the swash plate 19.

A plurality of cylinder bores 12a are formed in the cylinder block 12. Single-headed piston 2
1 has a head portion 21a reciprocally housed in each cylinder bore 12a, and a tail portion 21b
Are moored to the outer periphery of the swash plate 19 via a pair of shoes 22. The compression reaction force accompanying the compression operation of the piston 21 is received by the front housing 11 via the shoe 22, the swash plate 19, the hinge mechanism 20, the rotary support 18, and the thrust bearing 18a.

The air supply passage 23 and the pressure increasing passage 24 are formed independently so as to connect the discharge chamber 13b and the crank chamber 15. The capacity control valve 25 is provided in the middle of the air supply passage 23. This capacity control valve 25
Is a control valve element 26 and a control valve hole 27 of the control valve element 26.
And a diaphragm 28 for adjusting the degree of opening with respect to. Then, the opening degree of the control valve hole 27 by the control valve body 26 is adjusted according to the suction pressure Ps acting on the diaphragm 28 via the pressure sensing passage 29.

The amount of refrigerant gas supplied from the discharge chamber 13b to the crank chamber 15 through the air supply passage 23 is changed by adjusting the opening of the capacity control valve 25. The pressure P in the crank chamber 15 acting before and after the piston 21
c and a pressure difference P between the pressure Pb in the cylinder bore 12a.
1 is adjusted. Thereby, the inclination angle of the swash plate 19 is changed, the stroke of the piston 21 is changed, and the discharge capacity is adjusted.

The bleed passage 30 is formed to connect the crank chamber 15 and the suction chamber 13a. The bleed passage 30 is provided with an axial passage 16 a formed at the center of the drive shaft 16, an inside of a housing recess 12 b formed at the center of the rear end side of the cylinder block 12, and a pressure relief formed at the center of the valve plate 14. The hole 14c is formed. The front end of the axial passage 16a is a radial bearing 1 having a front end.
7 is open to the crank chamber 15. Thrust bearing 16c and shaft support spring 16d
Is interposed between the rear end of the drive shaft 16 and the valve plate 14 in the accommodation recess 12b.

Next, a description will be given of a configuration for reducing the discharge capacity in the acceleration operation state, which is a main part of the present invention. As shown in FIG. 2, a differential pressure valve 31 is provided in the pressure increasing passage 24. The differential pressure valve 31 includes a valve element 33 housed in a valve chamber 32 formed at an end of the pressure-raising passage 24 on the side of the crank chamber 15. This valve element 33 is a coiled spring 3
4 is always biased to a position to close the pressurizing passage 24. The spring 34 is held by spring receivers 35 and 36.

A spool accommodating chamber 41 is formed in the end face of the cylinder block 12 on the valve plate 14 side, and a spool 42 is accommodated in the chamber 41 in a reciprocating manner.
The rod 43 connected to one end surface of the spool 42 passes through an insertion hole 12 c formed in the cylinder block 12 and is in contact with the valve body 33. The spool storage chamber 4
The space on the left of 1 is a first pressure-sensitive chamber 44, and the space on the right is a second pressure-sensitive chamber 45. The second pressure-sensitive chamber 45 is connected to the discharge chamber 13b by a communication hole 46 formed in the valve plate 14. A throttle passage 47 is formed in the spool 42 for communicating the first pressure-sensitive chamber 44 and the second pressure-sensitive chamber 45, and the discharge pressure Pd of the discharge chamber 13b is provided in the first pressure-sensitive chamber 44. It works through the communication hole 46, the second pressure sensing chamber 45 and the throttle passage 47. A spring 48 as a coil-shaped urging member is accommodated in the first pressure-sensitive chamber 44, and the spool 42 is always reduced by reducing the volume of the valve plate 14 side, that is, the second pressure-sensitive chamber 45. Are urged in a direction to close the boost passage 24. Note that a seal ring 49 is attached to the outer peripheral surface of the spool 42.

Next, the operation of the variable displacement compressor configured as described above will be described. In this compressor, when the drive shaft 16 is rotated by an external drive source such as a vehicle engine, the swash plate 19 is integrally rotated via the rotation support 18 and the hinge mechanism 20. The rotational movement of the swash plate 19 is converted into a reciprocating linear movement of the piston 21 via the shoe 22, and the head 21a of the piston 21 is reciprocated in the cylinder bore 12a. By the reciprocating motion of the piston 21, refrigerant gas is sucked from the suction chamber 13a into the cylinder bore 12a via the suction valve 14a, compressed until reaching a predetermined pressure, and discharged through the discharge chamber 13b through the discharge valve 14b.
Is discharged to

Next, a normal displacement control operation of the variable displacement compressor will be described. When the compressor is stopped, the pressures in the suction chamber 13a, the discharge chamber 13b, and the crank chamber 15 are
It is almost balanced. At this time, the control valve body 26 of the capacity control valve 25 is held at a position where the control valve hole 27 is closed. When the compressor is started in this state, the head portion 21a of the piston 21 is reciprocated in the cylinder bore 12a as described above. The reciprocating motion of the piston 21 compresses the refrigerant gas and discharges the refrigerant gas to the discharge chamber 13b.

When the temperature in the vehicle compartment is high and the cooling load is large, the suction pressure Ps in the suction chamber 13a is high, and the pressure Pc in the crank chamber 15 and the pressure Pb in the cylinder bore 12a pass through the piston 21 via the piston 21. There is almost no differential pressure δP1. For this reason, the swash plate 19 is arranged at the maximum inclination state shown by the solid line in FIG. 1, the stroke of the piston 21 is increased, and the compressor is operated at the maximum displacement. On this occasion,
Since a high suction pressure Ps acts on the diaphragm 28 of the displacement control valve 25 via the pressure-sensitive passage 29, the control valve body 26 remains in a state where the control valve hole 27 is closed. That is, the supply passage 23 is shut off, and the supply of the high-pressure refrigerant gas from the discharge chamber 13b to the crank chamber 15 is stopped.

During the compression and discharge strokes in which the piston 21 is moved from the bottom dead center position to the top dead center position, blow-by gas flows into the crank chamber 15 from the gap between the outer peripheral surface of the piston 21 and the inner peripheral surface of the cylinder bore 12a. Inflow. Here, the blow-by gas flowing into the crank chamber 15 is supplied to the axial passage 16 a forming the bleed passage 30 and the accommodating recess 12.
b, and is returned to the suction chamber 13a via the pressure release hole 14c. As a result, a rise in pressure due to blow-by gas in the crank chamber 15 is suppressed, and the operation of the compressor with a large discharge capacity is continued.

When the temperature in the passenger compartment decreases and the cooling load decreases, the suction pressure Ps in the suction chamber 13a decreases. This low suction pressure Ps is applied to the displacement control valve 2 via the pressure sensing passage 29.
5 acts on the diaphragm 28 and the diaphragm 2
8 is displaced according to the degree of reduction of the suction pressure Ps. With the displacement of the diaphragm 28, the control valve body 26 is moved in a direction to open the control valve hole 27, and the opening area of the supply passage 23 at the capacity control valve 25 is increased. Then, high-pressure refrigerant gas is supplied from the discharge chamber 13b to the air supply passage 2
3 to the crank chamber 15. The flow rate of the refrigerant gas supplied to the crank chamber 15 is controlled by the control valve hole 27.
Is changed according to the opening of the vehicle. As a result, the crank chamber 15
Rises, and this pressure Pc and the cylinder bore 1
The first differential pressure δP1 between each piston 21 and the pressure Pb in 2a increases. In accordance with the first differential pressure δP1, the swash plate 19 is tilted to the minimum tilt side, the stroke of the piston 21 is reduced, and the discharge capacity is reduced.

When the temperature in the passenger compartment further decreases and approaches a state where the cooling load hardly exists, the suction chamber 1
The suction pressure Ps in the pressure control valve 3a further decreases, and the displacement control valve 2
The fifth control valve hole 27 is opened at the maximum opening. In this state, high-pressure refrigerant gas is discharged from the discharge chamber 13b into the air supply passage 2
3 is supplied to the crank chamber 15 in large quantities. Therefore, the first differential pressure δP1 between the pressure Pc in the crank chamber 15 and the pressure Pb in the cylinder bore 12a via each piston 21
Is further increased, and the swash plate 19 is disposed in the minimum inclination state shown by a chain line in FIG. Then, the stroke of the piston 21 is further reduced, and the compressor is operated at the minimum displacement.

On the other hand, when the operation of the compressor in a certain discharge capacity state is continued and the temperature in the passenger compartment increases and the cooling load increases, the suction pressure Ps in the suction chamber 13a increases. In this state, the increased suction pressure Ps acts on the diaphragm 28 of the capacity control valve 25 via the pressure-sensitive passage 29, and the diaphragm 28 is displaced in accordance with the degree of increase of the suction pressure Ps. With the displacement of the diaphragm 28, the control valve body 26 is moved in a direction to close the control valve hole 27, and the opening area of the air supply passage 23 at the capacity control valve 25 is reduced. Then, the flow rate of the high-pressure refrigerant gas supplied from the discharge chamber 13b to the crank chamber 15 through the air supply passage 23 is reduced. As a result, the pressure Pc of the crank chamber 15
And the first differential pressure δP1 between the pressure Pc in the crank chamber 15 and the pressure Pb in the cylinder bore 12a via each piston 21 decreases. According to the first differential pressure δP1,
The swash plate 19 is moved to the maximum tilt angle side, the stroke of the piston 21 is increased, and the discharge capacity is increased.

When the temperature in the passenger compartment further increases and the cooling load further increases, the suction pressure Ps in the suction chamber 13a also increases accordingly. When the high suction pressure Ps acts on the diaphragm 28 of the capacity control valve 25 via the pressure sensing passage 29, the control valve body 26 closes the control valve hole 27, and the air supply passage 23 is shut off. Then, the high-pressure refrigerant gas from the discharge chamber 13b is not supplied to the crank chamber 15. Thereafter, the refrigerant gas in the crank chamber 15 is exclusively extracted into the suction chamber 13a through the bleed passage 30, and the pressure Pc in the crank chamber 15 decreases so as to approach the suction pressure Ps in the suction chamber 13a. Therefore, the first differential pressure δP1 between the pressure Pc in the crank chamber 15 and the pressure Pb in the cylinder bore 12a via the pistons 21 is reduced, and the swash plate 19 is arranged at the maximum inclination. Then, the stroke of the piston 21 is increased, and the compressor is operated at the maximum discharge capacity.

As described above, in the variable displacement compressor configured as described above, the opening degree of the displacement control valve 25 in accordance with the cooling load, that is, the fluctuation of the suction pressure Ps, is adjusted so that the crank chamber 1
5, the discharge capacity is changed by raising and lowering the pressure Pc, and finally has a role of making the suction pressure Ps substantially constant.

Under these conditions, the drive shaft 16
Is normally rotated at a predetermined rotation speed, the first pressure-sensitive chamber 45 on the front side of the spool 42 is supplied through a throttle passage 47 provided in the spool 42 to a substantially constant pressure slightly lower than the discharge pressure Pd. The steady discharge pressure Pd1 acts. Further, a substantially constant discharge pressure Pd acts on the second pressure-sensitive chamber 45. Therefore, the second differential pressure δP2 between the discharge pressure Pd acting on the second pressure-sensitive chamber 45 and the steady discharge pressure Pd1 acting on the first pressure-sensitive chamber 44
Does not reach the predetermined value P in FIG. Regardless of the rotation speed of the drive shaft 16, if the rotation speed is in a non-acceleration state, the second rotation is similarly performed regardless of the magnitude of the discharge capacity.
The differential pressure δP2 does not reach the predetermined value P. For this reason,
As shown by the solid line in FIG. 1, the valve element 33 of the differential pressure valve 31 is arranged at the closed position of the valve hole 32a by the spring 34, and the boosting passage 24 is held in a closed state. Then, the compressor is subjected to a normal displacement control operation by the displacement control valve 25 described above.

On the other hand, in an acceleration state in which the rotation speed of the engine of the vehicle is moved from the steady rotation speed to the high rotation speed at a high speed, the rotation speed of the drive shaft 16 of the compressor is also changed to the steady rotation speed N1 as shown in FIG. To a high speed N2 at high speed, the piston 21 increases the discharge capacity of the refrigerant gas,
The discharge pressure Pd in the discharge chamber 13b sharply rises and acts on the second pressure-sensitive chamber 45. On the other hand, since the first pressure-sensitive chamber 44 communicates with the second pressure-sensitive chamber 45 via the throttle passage 47, the pressure rise is slow. For this reason, the second differential pressure δP2 rises above the predetermined value P, and the spool 42
Is pushed in a direction to decrease the volume of the first pressure sensing chamber 44 against the urging force of the first pressure sensing chamber 44, and the valve body 33 is opened by the rod 43 against the urging force of the spring 34 to open the valve hole 32a of the pressure increasing passage 24. Moved in the direction. As a result, the high-pressure refrigerant gas in the discharge chamber 13b is supplied from the boost passage 24 into the crank chamber 15, and the first differential pressure δP1 between the crank chamber pressure Pc and the pressure Pb in the cylinder bore increases, and The inclination angle of the plate 19 is reduced, and the discharge capacity is reduced. For this reason, when the engine is accelerating, the load acting on the engine is reduced,
As the acceleration performance increases, the fuel consumption efficiency can be improved.

The above-described acceleration operation is performed when the compressor is in a large capacity state or a medium capacity operation state and the second differential pressure δP2 becomes a predetermined value P or more by being accelerated from a steady rotation speed. As shown in FIG. 4, in the small capacity operation state, even if the drive shaft 16 is accelerated and rotated, the second differential pressure δP2
Does not exceed the predetermined value P, so that the differential pressure valve 31 is not operated.

When the compressor is operated at a predetermined rotation speed N2 after the acceleration state ends, the spool 42
Is returned to the predetermined value P or less, the valve body 33 closes the pressure increasing passage 24. Then, since the pressure Pc in the crank chamber 15 decreases and the first differential pressure δP1 decreases, the inclination angle of the swash plate 19 increases, and the compressor returns to the large capacity operation.

The effects that can be expected from the first embodiment will be described below. (A) In the variable displacement compressor of the first embodiment,
A differential pressure valve 31 having a valve element 33 and a spool 42 is provided in the pressure passage 24 between the discharge chamber 13 b and the crank chamber 15. And the speed of the compressor is accelerated,
When the discharge pressure Pd rises and the second differential pressure δP2 acting before and after the spool 42 becomes equal to or more than a predetermined value P, the valve element 33 is actuated to open the pressure increasing passage 24. For this reason, in the compression operation state with a large discharge capacity,
When the driving load is accelerated and the compression load becomes extremely large, the pressure increasing passage 2 by the differential pressure valve 31 is used.
With the opening of 4, the pressure Pc in the crank chamber 15 is increased, and the discharge capacity is reduced. Moreover, the structure of the differential pressure valve 31 can be simplified to facilitate the production and assembly work, and the compression load is reliably reduced, so that the performance of sliding parts in the compressor is prevented from deteriorating. The overall durability can be improved.

In the first embodiment, as shown in FIG. 4, as the discharge capacity during the compression operation increases, the rate of increase of the discharge pressure Pd increases with an increase in the rotation speed of the drive shaft 16. In the low-speed range of acceleration rotation, the second
When the differential pressure δP2 exceeds the predetermined value P, the differential pressure valve 31 is operated as described above, and the discharge capacity is reduced.

(B) In the variable displacement compressor of the first embodiment, the pressure acting before and after the spool 42 is slightly lower than the discharge pressure Pd through the discharge pressure Pd and the throttle passage 47 to the first pressure-sensitive chamber 44. A steady pressure Pd1 was applied. For this reason, after the acceleration is completed, pressure is supplied from the second pressure-sensitive chamber 45 to the first pressure-sensitive chamber 44 via the throttle passage 47,
The spool 42 is returned to the original position by the spring 48, and the boosting passage 24 is closed by the on-off valve 31, so that the discharge capacity can be increased in the steady operation.

If the throttle passage 47 of the spool 42 is omitted, the suction pressure Ps in the suction chamber 13a is supplied to the first pressure sensing chamber 44.
Also, when the crank chamber pressure Pc is applied, the discharge capacity cannot be increased unless the rotation speed decreases after the end of the acceleration operation.

(C) In the first embodiment, the differential pressure valve 31
Are accommodated in the valve chamber 32 and the accommodation chamber 44 formed in the cylinder block 12 and the position of the spool 42 is regulated by the valve plate 14, so that the valve number is increased without increasing the number of parts. The body 33 and the spool 42 can be assembled.

(D) In the first embodiment, the discharge chamber 13
A capacity control valve 25 is provided in the middle of the air supply passage 23 between b and the crank chamber 15. The capacity control valve 25 adjusts the supply amount of the high-pressure refrigerant gas from the discharge chamber 13b to the crank chamber 15 so that the crank chamber 1
The pressure Pc of 5 is raised and lowered to change the discharge capacity. Therefore, the high-pressure refrigerant gas in the discharge chamber 13b is directly supplied to the crank chamber 15 according to the increase or decrease of the cooling load, and the pressure Pc of the crank chamber 15 is changed quickly. Therefore, the responsiveness to the fluctuation of the cooling load of the compressor can be improved.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, the air supply passage 23 described in the first embodiment and the capacity control valve 25 provided in the middle thereof are omitted. This compressor is always operated at the maximum capacity without capacity control in the steady operation state. That is, the first differential pressure δP1 between the pressure Pc in the crank chamber 15 and the pressure Pb in the cylinder bore 12a through each piston 21 becomes equal to or less than a predetermined value, and the compressor is operated with a large capacity. The pressure increasing passage 24 is opened by the differential pressure valve 31, and the compressor is switched from large capacity to small capacity operation.

In the second embodiment, the volume of the first pressure sensing chamber 44 is larger than the volume of the first pressure sensing chamber 44 of the first embodiment. For this reason, the moving speed of the spool 42 can be reduced due to leakage of gas flowing from the first pressure sensing chamber 44 to the second pressure sensing chamber 45 through the throttle passage 47, and the shift from the minimum capacity to the maximum capacity after the end of acceleration. Can be performed smoothly.

Other configurations in the second embodiment,
The function and effect are the same as those of the configuration, function and effect (a), (b) and (c) of the first embodiment. Next, a third embodiment of the present invention will be described with reference to FIG.

In the third embodiment, the spool 42
43a for opening and closing the pressure passage 24 with respect to the rod 43
Are integrally formed. That is, when the spool 42 is moved leftward against the urging force of the spring 48 in FIG.
The passage 43b formed in the valve body 43a communicates with the valve hole 24a of the pressure increasing passage 24 to supply high-pressure refrigerant gas from the discharge chamber 13b to the crank chamber 15, and the compressor is switched from a large capacity to a small capacity in an accelerated state. .

In the third embodiment, the number of components of the differential pressure regulating valve 31 can be reduced as compared with the first embodiment, and assembly and manufacture can be performed easily. Other configurations, operations, and effects of the third embodiment are the same as the configurations, operations, and effects (a), (b), (c), and (d) of the first embodiment.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, the bleed passage 30 of the first embodiment is omitted, and the crank chamber 15
A differential pressure valve 31 is provided in a pressure release passage 51 for releasing the refrigerant gas from the suction chamber 13a into the suction chamber 13a and releasing the pressure. And
In the acceleration state, when the second differential pressure δP2 becomes equal to or more than the predetermined value P and the spool 42 of the differential pressure valve 31 is operated, the valve body 43a of the rod 43 causes the valve hole 51a of the pressure release passage 51 to be opened.
Is closed, the release of gas from the crank chamber 15 to the suction chamber 13a is prevented, the pressure Pc in the crank chamber 15 increases, the first differential pressure δP1 exceeds a predetermined value, and the inclination angle of the swash plate 19 decreases. The compressor can be switched from large capacity to small capacity.

The other structure, operation, and effect of the fourth embodiment are the same as the structure, operation, and effects (a), (b), and (c) of the first embodiment. The embodiments of the present invention can be embodied as follows.

In each of the above embodiments, the spool 4
2 is omitted, and the valve element 33 is omitted.
The rod 43 and the spool 42 are urged in one direction by the coil spring 34 that urges the coil 43.

In this alternative example, the number of parts can be reduced and the structure can be simplified. In the above embodiments, the seal ring 49 is omitted. In this alternative example, the number of parts can be reduced and the structure can be simplified.

In each of the above embodiments, the differential pressure valve 31
May be changed from a lower portion of the cylinder block 12 to an upper portion, or a portion of the rear housing 13 may be provided.

A check valve (not shown) is provided in the middle of a discharge pipe connected from the discharge chamber 13b to the external refrigerant circuit. In the case of this alternative example, after the acceleration rotation is completed and the pressure Pc in the crank chamber rises and the operation shifts from a large capacity to a small capacity operation, when the check valve is closed, the discharge pressure tends to increase, and the piston 21 and the swash plate 19
Can easily increase, and the capacity returnability from small capacity to large capacity can be improved.

In the first embodiment, the air supply passage 23 and the capacity control valve 25 are omitted, the bleed passage 30 is changed to the cylinder block 12 side, and the capacity control valve 25 is connected to the bleed passage 30. To arrange.

In this alternative example, when the cooling load is large by the capacity control valve 25, the bleed passage 30 is opened, the first differential pressure δP1 becomes small, the discharge capacity becomes large, and conversely, when the cooling load is small. The bleed passage 30 is closed, the first differential pressure δP1 increases, and the discharge capacity decreases.

In the above-described embodiment, a compressor of the type in which the piston 21 is reciprocated by the swash plate 19 as a cam plate is embodied, but this is a non-rotating oscillating tilt disclosed in Japanese Patent Application Laid-Open No. 8-302157. Applicable to a compressor that reciprocates a piston using a plate and a piston rod.

[0064]

The present invention is configured as described above, and has the following effects. According to the first and third aspects of the present invention, it is possible to reliably detect the acceleration state and switch the discharge capacity from a large capacity to a small capacity.
After the end of the acceleration, the discharge capacity can be increased, and the operation reliability can be improved.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in the above, the refrigerant gas in the discharge pressure region can be quickly introduced into the crank chamber from the pressure increasing passage during the acceleration rotation of the drive shaft, the capacity can be quickly reduced, and the acceleration performance can be further improved. Can be.

According to the fourth aspect of the present invention, the first aspect is provided.
In addition to the effects of the invention described in (1), the configuration of the differential pressure valve can be simplified. According to the fifth, sixth, seventh and eighth aspects, the configuration of the differential pressure valve can be further simplified.

According to the ninth, tenth, and eleventh aspects, in addition to the effects of the first aspect, the discharge capacity can be controlled in accordance with the cooling load.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a variable displacement compressor according to a first embodiment.

FIG. 2 is an enlarged sectional view showing a closed state of a differential pressure valve.

FIG. 3 is an enlarged sectional view showing an open state of a differential pressure valve.

FIG. 4 is a graph showing a relationship between a rotation speed of a drive shaft and a discharge pressure.

FIG. 5 is a sectional view showing a variable displacement compressor according to a second embodiment.

FIG. 6 is a sectional view showing a main part of a variable displacement compressor according to a third embodiment.

FIG. 7 is a sectional view showing a main part of a variable displacement compressor according to a fourth embodiment.

[Explanation of symbols]

Reference numeral 11 denotes a front housing constituting a part of the housing, 12 represents a cylinder block constituting a part of the housing, 12a represents a cylinder bore, 13 represents a rear housing constituting a part of the housing, and 13a represents a suction chamber constituting a suction pressure region. .., 13b... Discharge chambers forming discharge pressure regions, 15
... Crank chamber, 16 ... Drive shaft, 19 ... Swash plate as cam plate, 21 ... Piston, 23 ... Air supply passage, 2
4 ... boost passage, 25 ... capacity control valve, 30 ... bleed passage, 3
1 ... differential pressure valve, 32 ... valve chamber, 32a ... valve hole, 33 ... valve body,
34: coiled spring, 41: accommodation chamber, 42: spool, 43: operating rod, 43a: valve body, 43b: passage,
44: first pressure sensing chamber, 45: second pressure sensing chamber, 46: communication passage,
47: throttle passage, 48: spring 48, 51: pressure release passage.

Claims (11)

[Claims] 1. A crank chamber is formed inside a housing and a drive shaft is rotatably supported. A cylinder bore is formed in a cylinder block constituting a part of the housing, and a piston can reciprocate in the cylinder bore. And a cam plate for reciprocatingly moving the piston is mounted on the drive shaft in a swingable manner, and a cam plate is provided in accordance with a first differential pressure between the pressure in a crank chamber and the pressure in a cylinder bore through the piston. In the variable displacement compressor in which the displacement is controlled by changing the inclination angle of the compressor, any one of a pressure increasing passage communicating the discharge pressure region with the crank chamber and a pressure releasing passage communicating the crank chamber with the suction pressure region On the other hand, when the second differential pressure between the pressure in the discharge pressure region during steady operation and the pressure in the discharge pressure region during acceleration becomes equal to or higher than a predetermined value, By closing the discharge or pressure release passage, the first differential pressure is increased to reduce the discharge capacity, and after the end of acceleration, the second differential pressure is returned to a predetermined value or less to operate to increase the discharge capacity. Variable displacement compressor with differential pressure valve. 2. The pressure difference valve according to claim 1, wherein the pressure difference valve is disposed in the middle of a pressure increasing passage, and a second pressure difference between a pressure in a discharge pressure region during steady operation and a pressure in a discharge pressure region during acceleration is predetermined. A variable capacity compressor configured to open the pressure increasing passage when the pressure exceeds the predetermined value, and to close the pressure increasing passage by returning the second differential pressure to a predetermined value or less after the end of acceleration. 3. The pressure difference valve according to claim 1, wherein the pressure difference valve is disposed in the middle of a pressure release passage, and a second pressure difference between a pressure in a discharge pressure region during a steady operation and a pressure in a discharge pressure region during an acceleration is maintained. A variable displacement compressor configured to close the pressure relief passage when the pressure exceeds a predetermined value, and to return the second differential pressure to a value less than or equal to the predetermined value and to open the pressure relief passage after the end of acceleration. 4. The pressure differential valve according to claim 1, wherein the differential pressure valve acts on a spool accommodated in the accommodation chamber so as to reciprocate, and a pressure in a discharge pressure region during a steady operation on one surface of the spool via a throttle passage. The first is formed on one side of the accommodation chamber.
A pressure-sensitive chamber, a second pressure-sensitive chamber formed on the other side of the storage chamber so as to apply a pressure in a discharge pressure area during acceleration to the other surface of the spool, and the second differential pressure is predetermined in an accelerated state. An opening / closing valve for opening the pressure-raising passage or closing the pressure-releasing passage when the spool is actuated beyond a predetermined value, and a bias for constantly biasing the spool in a direction in which the opening / closing valve is closed or opened. And a variable capacity compressor. 5. The variable displacement compressor according to claim 4, wherein the spool, the on-off valve and the biasing member are formed in a housing chamber and a valve chamber formed in the cylinder block. 6. The variable displacement compressor according to claim 4, wherein the throttle passage is formed to communicate the first pressure-sensitive chamber and the second pressure-sensitive chamber with the spool. 7. The valve according to claim 4, wherein the on-off valve is pushed by an operating rod connected to the spool, and the valve is always in a closed position of the pressure increasing passage. Alternatively, a variable displacement compressor formed by an urging member that presses an open position of the pressure release passage. 8. The variable displacement compressor according to claim 7, wherein the urging member of the valve body also serves as the urging member for urging the spool. 9. The first pressure difference according to claim 1, wherein one of an air supply passage communicating the discharge pressure region with the crank chamber and a bleed passage communicating the crank chamber with the suction pressure region. Variable displacement compressor provided with a displacement control valve that changes the pressure according to the cooling load. 10. The displacement control valve according to claim 9, wherein the displacement control valve is disposed in the middle of the air supply passage, and the displacement control valve controls the supply amount of the refrigerant gas from the discharge pressure region to the crank chamber. , A variable displacement compressor configured to change the displacement. 11. The displacement control valve according to claim 9, wherein the displacement control valve is disposed in the middle of the bleed passage, and the displacement control valve adjusts the amount of refrigerant gas extracted from the crank chamber to the suction pressure region. A variable displacement compressor configured to change the displacement.