JPH1061549A - Variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce compressive load of a variable displacement and improve its durability by reducing and controlling the discharge by a simple structure when the number of revolution of a driving shaft exceeds the specified value in the compressing operation of large discharge displacement. SOLUTION: A differential pressure regulating valve 31 is provided on either a boosting passage 24 for communicating a discharge pressure range 13b with a crank chamber 15 or a pressure discharging passage for communicating the crank chamber 15 with an intake pressure range 13a. When differential pressure between pressure of the crank chamber 15 and pressure of the intake pressure range 13a exceeds the specified value, the differential pressure regulating valve 31 is operated, pressure of the crank chamber 15 is boosted, and the discharge is reduced.

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.

[0003]

However, in this conventional variable displacement compressor, when the cam plate is arranged at a large inclination angle and a compression operation with a large discharge capacity is performed, an external device such as a vehicle engine is not operated. The rotation speed of the drive source has increased,
The drive shaft may be rotated at high speed. In such a case, the compression load sharply increases, and the Pv value (the value of the product of the surface pressure between the sliding contact surfaces and the sliding speed) of the sliding portion in the compressor greatly increases, and the sliding load increases. There has been a problem that the working life of the moving part and, consequently, the compressor is shortened.

The present invention has been made by paying attention to such problems existing in the conventional technology. The purpose is to reduce the compression load with a simple configuration and reduce the compression load when the rotation of the drive shaft exceeds a predetermined value during the compression operation with a large discharge capacity. An object of the present invention is to provide a variable displacement compressor that can be improved.

[0005]

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. The cylinder block is formed with a cylinder bore, and a piston is housed in the cylinder bore so as to be reciprocable. A cam plate is supported on the drive shaft so as to be integrally rotatable and swingable. The pressure difference between the pressure in the crank chamber and the pressure in the cylinder bore through the piston is changed based on the degree adjustment, and the displacement is controlled by changing the inclination angle of the cam plate according to the pressure difference. In capacity compressors,
A differential pressure between the pressure in the crank chamber and the pressure in the suction pressure area is provided in one of the pressure increasing passage that communicates the discharge pressure area and the crank chamber or the pressure release path that communicates the crank chamber and the suction pressure area. A differential pressure valve is provided which operates so as to reduce the discharge capacity when the pressure exceeds a predetermined value.

According to a second aspect of the present invention, in the variable displacement compressor according to the first aspect, the displacement control valve is disposed in the middle of an air supply passage communicating the discharge pressure region and the crank chamber. The displacement control valve changes the supply amount of the refrigerant gas from the discharge pressure region to the crank chamber, thereby changing the discharge displacement.

According to a third aspect of the present invention, in the variable displacement compressor according to the first aspect, the displacement control valve is disposed in the middle of a bleed passage communicating the crank chamber and the suction pressure region. The discharge capacity is changed by adjusting the amount of refrigerant gas extracted from the crank chamber to the suction pressure region by the control valve.

[0008] In the invention described in claim 4, claims 1 to 3 are provided.
In the variable displacement compressor according to any one of the above, the differential pressure valve is disposed in the middle of the pressure increasing passage, and when the differential pressure between the pressure in the crank chamber and the pressure in the suction pressure region becomes equal to or higher than a predetermined value, The pressure increasing passage is opened by the differential pressure valve.

According to the fifth aspect of the present invention, the first to third aspects are provided.
In the variable displacement compressor according to any one of the above, the differential pressure valve is disposed in the middle of the pressure release passage, and when the differential pressure between the pressure in the crank chamber and the pressure in the suction pressure region becomes equal to or more than a predetermined value, The pressure release passage is closed by this differential pressure valve.

In the variable displacement compressor according to the first aspect, when the drive shaft is rotated by an external drive source such as a vehicle engine, the piston reciprocates via the cam plate, and the cam plate tilts. The compression of the refrigerant gas is performed at a discharge capacity corresponding to the pressure.

Here, if the cam plate is arranged in a large inclination state, the stroke of the piston becomes large, and the compression operation with a large discharge capacity is performed. At this time, when the rotation speed of an external drive source such as a vehicle engine is increased and the drive shaft is rotated at a high speed, the reciprocating inertial force of the piston is greatly increased, and a moment in the capacity increasing direction is generated. And
In this high-speed rotation state, in order to maintain a predetermined discharge capacity, the pressure in the crank chamber rises in proportion to the moment. When the pressure difference causes the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region to reach a predetermined value or more, the differential pressure valve is actuated, and the piston pressure between the pressure in the crank chamber and the pressure in the cylinder bore is reduced to reduce the discharge capacity. Is changed.

By the way, the larger the stroke of the piston, the larger the moment in the capacity increasing direction. The higher the rotation speed of the drive shaft and the higher the reciprocating speed of the piston, the larger the moment. Then, the pressure in the crank chamber increases to balance this moment. On the other hand, the pressure in the suction pressure region is controlled to be substantially constant by the capacity control operation of the compressor. For this reason, as the operation is performed with a large discharge capacity, and as the drive shaft is rotated at a high speed,
The pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region becomes large. Here, the differential pressure valve is activated when the differential pressure becomes equal to or higher than a predetermined value. Therefore, the differential pressure valve is operated at a lower rotation speed as the discharge capacity is larger.

In the variable displacement compressor according to the present invention, the pressure of the crank chamber is changed by adjusting the supply amount of the refrigerant gas from the discharge pressure region to the crank chamber by the displacement control valve. The capacity is changed. Therefore, the high-pressure refrigerant gas in the discharge pressure region is directly supplied to the crank chamber in accordance with the increase or decrease of the cooling load, and the pressure in the crank chamber is quickly changed.

In the variable displacement compressor according to the third aspect, the pressure in the crank chamber is changed by adjusting the amount of refrigerant gas extracted from the crank chamber to the suction pressure region by the displacement control valve, thereby changing the pressure in the crank chamber. The capacity is changed. Here, the pressure in the crank chamber is increased mainly by the blow-by gas flowing from the gap between the piston and the cylinder bore. For this reason, the pressure in the crank chamber is gradually increased, and the influence of the pressure increase on the sliding portion in the crank chamber is reduced, and the durability of the sliding portion can be improved.

[0015] In the variable displacement compressor according to the fourth aspect, the differential pressure valve is normally kept in a state in which the pressure increasing passage is closed. Then, during the compression operation with a large discharge capacity, when the drive shaft is rotated at a high speed and the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region exceeds a predetermined value, the pressure difference valve is actuated to open the pressure increasing passage. You. Thus, high-pressure refrigerant gas is supplied from the discharge pressure region into the crank chamber via the pressure increasing passage. And the pressure in the crankcase is increased,
The cam plate tilt angle is reduced, the discharge capacity is reduced, and the compression load is reduced.

In the variable displacement compressor according to the fifth aspect, the differential pressure valve is normally kept in a state where the pressure release passage is opened. Then, during a compression operation with a large discharge capacity, the drive shaft is rotated at a high speed, and when the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region exceeds a predetermined value, the pressure difference valve is actuated and the pressure release passage is opened. Closed. Thus, the flow of the refrigerant gas extracted from the crank chamber to the suction pressure region via the pressure release passage is shut off. The pressure in the crank chamber is increased by the blow-by gas flowing through a small gap between the piston and the cylinder bore, the inclination angle of the cam plate is reduced, the discharge capacity is reduced, and the compression load is reduced.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described 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 region and a discharge chamber 13b forming a discharge pressure region 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 rotary support 18 is provided with the drive shaft 16.
It is fixed to. Also, a swash plate 1 as a cam plate
9 is supported by a drive shaft 16 in a crank chamber 15 so as to be slidable and tiltable in the axial direction. The swash plate 19 is connected to the rotating support 18 via a hinge mechanism 20. The swash plate 19 is guided by its hinge mechanism 20 in sliding movement and tilting in the axial direction, and is rotated integrally 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 attached to the drive shaft 16.
b and the swash plate 19 are in contact with each other.

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 supply passage 23 and the boost passage 24 are formed 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 provided with a control valve body 26.
And a diaphragm 28 for adjusting the opening of the control valve body 26 with respect to the control valve hole 27. Then, according to the suction pressure Ps acting on the diaphragm 28 via the pressure sensing passage 29, the control valve hole 27 formed by the control valve body 26 is controlled.
Is adjusted.

By adjusting the opening of the capacity control valve 25, the supply amount of the refrigerant gas supplied from the discharge chamber 13b to the crank chamber 15 through the air supply passage 23 is changed. The pressure P in the crank chamber 15 acting before and after the piston 21
The pressure difference between c and the pressure in the cylinder bore 12a 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.

The differential pressure valve 31 is arranged in the pressure passage 24. The differential pressure valve chamber 32 of the differential pressure valve 31 is formed in the cylinder block 12 so as to communicate with the pressure increasing passage 24, and a differential pressure valve hole 33 is formed on a peripheral side thereof.
The differential pressure valve body 34 is movably accommodated in the differential pressure valve chamber 32, and is urged by a closing spring 35 in a direction in which the differential pressure valve hole 33 closes. The communication hole 36 is formed in the valve plate 14, and makes the rear end of the differential pressure valve chamber 32 communicate with the suction chamber 13a.

Next, the operation of the variable capacity 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, the 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 difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via the piston 21 is increased. Almost no. 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. At this time, since the high suction pressure Ps acts on the diaphragm 28 of the displacement control valve 25 via the pressure sensing passage 29, the control valve body 26 remains in the 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 air 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
, The pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a through each piston 21 increases. In accordance with this differential pressure, the swash plate 19 is moved to the minimum tilt angle 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. For this reason, the pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a through the respective pistons 21 is further increased, and the swash plate 19 is arranged in the minimum inclination state shown by the 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 vehicle 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 in 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 pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via each piston 21 decreases. In accordance with this differential pressure, the swash plate 19 is moved to the maximum tilt angle side, the stroke of the piston 21 is increased, and the displacement is increased.

When the temperature in the vehicle 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. Then, the refrigerant gas in the crank chamber 15 is exclusively extracted into the suction chamber 13a via 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 differential pressure between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a through each piston 21 becomes small, and the swash plate 1
9 is arranged in a maximum tilt state. And the piston 21
Is increased, and the compressor is operated at the maximum displacement.

As described above, the variable displacement compressor configured as described above adjusts the opening degree of the displacement control valve 25 in accordance with the cooling load, that is, the variation of the suction pressure Ps, to thereby control 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.

As described above, when the rotational speed of an external drive source such as a vehicle engine is increased during the compression operation with a large discharge capacity, the drive shaft 16 is rotated at a high speed. In this state, the reciprocating speed of the piston 21 increases as the rotational speed of the drive shaft 16 increases, and the stroke of the piston 21 increases, and the reciprocating inertial force F of the piston 21 shown in FIG. Have been. Due to the increase of the reciprocating inertia force F, the swash plate 1
A moment M in the capacity increasing direction centering on the center of 9 is generated. The moment M increases as the discharge capacity increases, and increases as the rotation speed of the drive shaft 16 increases. Then, in order to maintain a predetermined discharge capacity, the capacity control valve 2 is adjusted so as to balance the moment M.
5, the pressure Pc in the crank chamber 15 increases. That is, as shown in FIG. 3, the pressure Pc in the crank chamber 15 increases as the discharge capacity increases and as the rotation speed of the drive shaft 16 increases. On the other hand, the suction chamber 13a
As described above, the suction pressure Ps is controlled to be substantially constant by the normal displacement control operation of the compressor.

Under these conditions, the drive shaft 16
Is rotated at a rotation speed equal to or lower than the predetermined value N1, the differential pressure between the pressure Pc in the crank chamber 15 and the suction pressure Ps in the suction chamber 13a does not reach the predetermined value P1 shown in FIG. Further, even when the drive shaft 16 is rotated at a rotation speed exceeding the predetermined value N1, if the discharge capacity is small, the same differential pressure does not reach the predetermined value P1. Therefore, as shown by the solid line in FIG. 1, the differential pressure valve body 34 of the differential pressure valve 31 is arranged at the closed position of the differential pressure valve hole 33, and the pressure increasing passage 24 is closed. Then, the compressor is subjected to the normal capacity control operation described above.

On the other hand, when the rotational speed of the drive shaft 16 increases and the pressure difference between the pressure Pc in the crank chamber 15 and the suction pressure Ps in the suction chamber 13a becomes equal to or higher than a predetermined value P1,
As shown by a chain line in FIG.
Is moved to the open position, and the pressurizing passage 24 is opened. Further, as shown in FIG. 3, the pressure Pc in the crank chamber 15 increases as the discharge capacity increases, and the differential pressure reaches the predetermined value P1 at a lower rotation speed. Is opened. That is, during operation with a large discharge capacity, the differential pressure is equal to the predetermined value P at the rotation speed N1.
When the pressure reaches 1, the pressure passage 24 is opened. On the other hand, during the operation at the medium discharge capacity, the pressure difference reaches the predetermined value P1 at the rotation speed N2 higher than the rotation speed N1, and
Is opened. Further, during operation with a small discharge capacity, the differential pressure does not reach the predetermined value P1 even when the rotation speed exceeds N2, and the differential pressure valve 31 remains closed.

When the pressurizing passage 24 is thus opened, high-pressure refrigerant gas is supplied from the discharge chamber 13b into the crank chamber 15, and the pressure Pc in the crank chamber 15 is increased as shown in FIG. Thus, the discharge capacity is reduced. Therefore, even when the drive shaft 16 is rotated at a high speed in the compression operation state with a large discharge capacity, an increase in the compression load can be avoided.

Incidentally, as shown in FIG.
Is operated, the suction amount of the refrigerant gas into the cylinder bore 12a is reduced, and the suction pressure in the suction chamber 13a is increased. As the suction pressure Ps increases, the cooling capacity also decreases. However, the rotation speed N1 at which the differential pressure valve 31 is operated is set to, for example, about 6,000 rpm, which can be reached only when the vehicle is running. For this reason,
During normal running of the vehicle, the discharge capacity of the compressor is reduced unnecessarily, and the cooling capacity is not reduced.

The effects that can be expected from the first embodiment will be described below. (A) In the variable displacement compressor of the first embodiment, the pressure increasing passage 2 between the discharge chamber 13a and the crank chamber 15
A differential pressure valve 31 is provided in the middle of 4. Then, the pressure Pc in the crank chamber 15 and the suction pressure Ps in the suction chamber 13a
When the pressure difference with the pressure difference becomes equal to or more than a predetermined value, the pressure difference valve 31 is operated to open the pressure increasing passage 24. Therefore, in a compression operation state with a large discharge capacity, when the drive shaft 16 is rotated at a high speed and the compression load becomes extremely large, the pressure in the crank chamber 15 is increased due to the opening of the pressure increasing passage 24 by the differential pressure valve 31. Pc is increased and the discharge capacity is reduced. Moreover, the configuration of the differential pressure valve 31 is simple. Therefore, the compression load is reliably reduced with a simple configuration, and the performance degradation of the sliding portion in the compressor is suppressed,
As a result, the durability of the entire compressor can be improved.

(B) In the variable displacement compressor of the first embodiment, the pressure Pc in the crank chamber 15 and the pressure in the suction chamber 1
When the pressure difference between the suction pressure Ps and the suction pressure Ps in the valve 3a becomes equal to or more than a predetermined value, the pressure difference valve 31 is operated to reduce the discharge capacity. For this reason, the larger the displacement during the compression operation, the lower the rotational speed of the drive shaft 16 becomes,
The differential pressure valve 31 is actuated, and the discharge displacement reduction control is started. Therefore, it is possible to appropriately reduce the increase in the compression load due to the high-speed rotation according to the discharge capacity of the compression operation.

(C) In the variable displacement compressor according to the first embodiment, a displacement control valve 25 is disposed in the air supply passage 23 between the discharge chamber 13b and the crank chamber 15. Then, by adjusting the supply amount of the high-pressure refrigerant gas from the discharge chamber 13b to the crank chamber 15 by the capacity control valve 25, the pressure Pc of the crank chamber 15 is raised and lowered to change the discharge capacity. It has become. 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. (Second Embodiment) Next, a second embodiment of the present invention will be described focusing on parts different from the first embodiment.

In the second embodiment, as shown in FIG. 5, a bleed passage 40 serving as a pressure release passage is formed between the crank chamber 15 and the suction chamber 13a. The bleed passage 40 is provided in the axial passage 16 at the center of the drive shaft 16.
a, a recess 12 in the center of the rear end of the cylinder block 12
b and the communication passage 40a. Capacity control valve 41
Is disposed in the middle of the communication passage 40 a of the bleed passage 40. The displacement control valve 41 includes a control valve element 42, a diaphragm 44 for adjusting the opening of the control valve element 42 with respect to the control valve hole 43, and a pressure-sensitive member 45. Then, the suction pressure Ps in the suction chamber 13 a acting on the diaphragm 44 via the first pressure sensing passage 46 and the discharge chamber 13 acting on the pressure sensing member 45 via the second pressure sensing passage 47.
The opening degree of the control valve hole 43 by the control valve body 42 is adjusted according to the discharge pressure Pd in b.

By adjusting the opening degree of the capacity control valve 41, the amount of refrigerant gas extracted from the crank chamber 15 to the suction chamber 13a through the bleed passage 40 is changed.
The pressure difference between the pressure Pc in the crank chamber 15 acting before and after the pressure and the pressure in the cylinder bore 12a 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 constant pressure supply path 48 is formed so as to connect the discharge chamber 13b and the crank chamber 15, and a fixed throttle 49 is provided in the middle thereof. A predetermined amount of high-pressure refrigerant gas is always supplied from the discharge chamber 13b into the crank chamber 15 through the constant-pressure supply path 48, so that the pressure Pc in the crank chamber 15 becomes equal to or higher than a predetermined value. Have been. Thereby, when adjusting the opening of the bleed passage 40 by the displacement control valve 41, the change speed of the inclination angle of the swash plate 19 can be increased, and the responsiveness of the discharge displacement change can be improved.

Further, in the second embodiment, a differential pressure valve 50 is provided in the bleed passage 40.
The differential pressure valve chamber 51 of the differential pressure valve 50 has a pair of differential pressure valve holes 52 formed at opposing positions on the peripheral side. Differential pressure valve element 5
3 is movably accommodated in the differential pressure valve chamber 51 and is urged by an opening spring 54 in a direction to open the differential pressure valve hole 52. The pair of communication holes 55 are formed in the cylinder block 12 and the valve plate 14, and communicate the front end of the differential pressure valve chamber 51 with the crank chamber 15 and the rear end of the suction chamber 13.
a.

Next, a normal displacement control operation of the variable displacement compressor according to the second embodiment will be described. Now, when the temperature in the vehicle compartment is high and the cooling load is large, the suction chamber 13
a, the suction pressure Ps in the crank chamber 15 is high.
And the pressure in the cylinder bore 12a through the piston 21 is hardly different. For this reason, the swash plate 19 is arranged at the maximum inclination state, the stroke of the piston 21 is increased, and the compressor is operated at a large displacement. In this state, the discharge pressure Pd in the discharge chamber 13b is also high, and the high discharge pressure Pd acts on the pressure-sensitive member 45 of the displacement control valve 41 via the second pressure-sensitive passage 47. The diaphragm 44 of the displacement control valve 41 has a first pressure-sensitive passage 4.
A high suction pressure Ps acts via 6. Therefore, both the pressure-sensitive member 45 and the diaphragm 44 are controlled by the control valve element 42.
Is displaced in a direction to open the control valve hole 43, and the control valve body 4
2 is in a state where the control valve hole 43 is opened. That is, the bleed passage 40 is opened and the crank chamber 15
The refrigerant gas inside is extracted into the suction chamber 13a through the bleed passage 40. Thus, the pressure Pc in the crank chamber 21 is increased by the blow-by gas flowing through the gap between the cylinder bore 12a and the piston 21 and the high-pressure refrigerant gas (hereinafter, referred to as leak gas) supplied through the constant-pressure supply passage 48. Without this, operation with a large discharge capacity is continued.

Here, 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 acts on the diaphragm 44 of the capacity control valve 41 via the first pressure sensing passage 46, and the diaphragm 44 responds to the degree of reduction of the suction pressure Ps by
The control valve body 42 is displaced in a direction to close the control valve hole 43. With the displacement of the diaphragm 44, the control valve element 4
2 is moved in the direction to close the control valve hole 43, and the opening area of the bleed passage 40 at the capacity control valve 41 is reduced. Then, the flow rate of the refrigerant gas extracted from the crank chamber 15 to the suction chamber 13 a through the bleed passage 40 is reduced according to the opening degree of the control valve hole 43. As a result, the pressure Pc of the crank chamber 15 is increased by the blow-by gas and the leak gas.
Rises. Then, the differential pressure between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via each piston 21 increases. In accordance with this differential pressure, the swash plate 19 is moved to the minimum tilt angle side, the stroke of the piston 21 is reduced, and the discharge capacity is reduced. Then, the discharge pressure Pd in the discharge chamber 13b also decreases.

When the temperature in the passenger compartment further decreases and approaches a state where the cooling load hardly exists, the suction chamber 1
3a and the discharge pressure P in the discharge chamber 13b.
d further decreases. Therefore, both the pressure sensing member 45 and the diaphragm 44 are displaced in the direction in which the control valve body 42 closes the control valve hole 43, and the control valve hole 43 is closed by the control valve body 42. In this state, the bleed passage 40 is shut off, and the flow of the refrigerant gas extracted from the crank chamber 15 to the suction chamber 13a is shut off. Therefore, the pressure Pc of the crank chamber 15 is further increased by the blow-by gas and the leak gas. Then, the differential pressure between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via each piston 21 increases. As a result, the swash plate 19 is arranged at the minimum inclination, 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 vehicle 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 is applied to the first pressure-sensitive passage 46.
And acts on the diaphragm 44 of the displacement control valve 41 to displace the diaphragm 44 in accordance with the degree of increase of the suction pressure Ps. With the displacement of the diaphragm 44, the control valve body 42 is moved in a direction to open the control valve hole 43, and the opening area of the bleed passage 40 at the capacity control valve 41 is increased. Then, the flow rate of the refrigerant gas extracted from the crank chamber 15 to the suction chamber 13a through the bleed passage 40 is increased. As a result, the pressure P in the crank chamber 15
c decreases, and the differential pressure between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via each piston 21 decreases. In accordance with this differential pressure, the swash plate 19 is moved to the maximum tilt angle side, the stroke of the piston 21 is increased, and the displacement is increased. Then, the discharge pressure Pd in the discharge chamber 13b also increases.

When the temperature in the passenger compartment further increases and the cooling load further increases, the suction pressure Ps in the suction chamber 13a and the discharge pressure Pd in the discharge chamber 13b further increase. In this state, both the pressure sensing member 45 and the diaphragm 44 are displaced in the direction in which the control valve body 42 opens the control valve hole 43, and the control valve body 42 is disposed at the maximum opening position of the control valve hole 43, and the bleed passage 40 is opened. And
From the crank chamber 15 to the suction chamber 13 through the first bleed passage 40
a becomes maximum, the pressure Pc in the crank chamber 15 becomes equal to the suction pressure Ps in the suction chamber 13a.
Decline to get closer. For this reason, each piston 2 of the pressure Pc of the crank chamber 15 and the pressure in the cylinder bore 12a
The swash plate 19 is arranged at the maximum tilt angle state due to the decrease in the pressure difference through the first swash plate 19. Then, the stroke of the piston 21 is increased, and the compressor is operated at the maximum discharge capacity.

When the rotational speed of an external drive source such as a vehicle engine is increased during the compression operation with a large discharge capacity, the center of the swash plate 19 is moved in the same manner as in the first embodiment. A moment M in the direction of the increase in the capacity with respect to the center is generated. Then, in order to maintain a predetermined discharge capacity, the opening degree of the capacity control valve 41 is adjusted so as to balance the moment M, and the pressure Pc of the crank chamber 15 is changed.

In this state, when the pressure difference between the pressure Pc in the crank chamber 15 and the suction pressure Ps in the suction chamber 13a is equal to or less than a predetermined value, as shown by a solid line in FIG.
The zero differential pressure valve body 53 is disposed at the open position of the differential pressure valve hole 52 by the urging force of the opening spring 54. And the bleed passage 40
Remains open, and the compressor is subjected to the normal displacement control operation described above.

On the other hand, when the pressure difference between the pressure Pc of the crank chamber 15 and the suction pressure Ps of the suction chamber 13a becomes equal to or greater than a predetermined value, the differential pressure valve body 53 The differential pressure valve hole 52 is moved to the closed position against the urging force. Then, the bleed passage 40 is closed, and the flow of the refrigerant gas extracted from the crank chamber 15 to the suction chamber 13a through the bleed passage 40 is shut off. For this reason, the pressure Pc in the crank chamber 15 is increased by the blow-by gas and the leak gas, and the discharge capacity is reduced. Therefore, similarly to the first embodiment, an increase in the compression load can be avoided even when the drive shaft 16 is rotated at a high speed in the compression operation state with a large discharge capacity.

The effects that can be expected from the second embodiment will be described below. (A) In the variable displacement compressor according to the second embodiment, in the bleed passage 40 between the crank chamber 15 and the suction chamber 13a, the differential pressure regulating valve 50 is disposed on the crank chamber 15 side with respect to the capacity control valve 41. Has been established. When the pressure difference between the pressure Pc of the crank chamber 15 and the suction pressure Ps of the suction chamber 13a becomes equal to or greater than a predetermined value, the pressure difference valve 50 is operated to close the bleed passage 40. For this reason, when the drive shaft 16 is rotated at a high speed and the compression load becomes very large in the compression operation state with a large discharge capacity, the differential pressure valve 50
With the closing of the bleed passage 40, the pressure Pc in the crank chamber 15 is gradually increased by the inflow of the blow-by gas and the leak gas. Then, the inclination angle of the swash plate 19 gradually decreases, and the discharge capacity is reliably reduced without causing a sudden increase in the temperature and pressure of the crank chamber 15. Therefore, the compression load can be reduced with a simple configuration, and the performance deterioration of the sliding portion in the compressor can be further suppressed.

(B) Also in the variable displacement compressor according to the second embodiment, similarly to the first embodiment described above, an increase in the compression load accompanying high-speed rotation is appropriately performed according to the discharge capacity of the compression operation. Can be relaxed.

(C) In the variable displacement compressor of the second embodiment, a displacement control valve 41 is provided in the bleed passage 40 between the crank chamber 15 and the suction chamber 13a. The displacement of the crank chamber 15 is controlled by the displacement control valve 41.
By adjusting the amount of refrigerant gas extracted from the suction chamber 13a to the suction chamber 13a, the pressure Pc of the crank chamber 15 is raised and lowered, and the discharge capacity is changed. Therefore, when the bleed passage 40 is closed, the pressure P in the crank chamber 15
c is gradually increased by the inflow of the blow-by gas and the leak gas, and the inclination angle of the swash plate 19 gradually decreases. Therefore, the discharge capacity can be reduced without causing a sudden rise in temperature and pressure in the crank chamber 15. As a result, the compression load can be reduced, and the durability of the compressor can be further improved.

The present invention can be embodied with the following modifications. (1) As shown in the first embodiment, the air supply passage 2
In the compressor in which the displacement control valve 25 is provided to control the discharge capacity, a differential pressure valve 50 as shown in the second embodiment is disposed in the bleed passage 30, so that the discharge at the time of high compression load is performed. To be configured to reduce the capacity.

(2) As shown in the second embodiment, in a compressor in which a displacement control valve 41 is provided in the bleed passage 40 to control the displacement, the discharge chamber 13b and the crank chamber 15 are connected to each other. A pressure increasing passage 24 communicating with the pressure increasing passage 24 is provided.
, So as to reduce the discharge capacity under a high compression load.

(3) In the second embodiment, a pressure release passage is formed between the crank chamber 15 and the suction chamber 13a independently of the bleed passage 40, and the differential pressure valve 5 is provided in the pressure release passage.
Arrange 0.

Even with such a configuration, substantially the same operation and effects as those of the above embodiments can be exerted.

[0063]

The present invention is configured as described above, and has the following effects. According to the first aspect of the invention, when the rotation speed of the drive shaft exceeds a predetermined value during the compression operation with a large discharge capacity, the discharge capacity can be reduced with a simple configuration. Therefore, the compression load can be reduced, and the durability of the compressor can be improved. Also, as the discharge capacity during the compression operation increases, the differential pressure valve is actuated at a point in time when the rotation speed of the drive shaft is low, and the discharge capacity reduction control is started. Therefore,
According to the discharge capacity of the compression operation, it is possible to appropriately reduce the increase in the compression load due to the high-speed rotation.

According to the second aspect of the present invention, the high-pressure refrigerant gas in the discharge pressure region is directly supplied to the crank chamber in accordance with the increase or decrease of the cooling load, and the pressure in the crank chamber is quickly changed. Therefore, the responsiveness to the fluctuation of the cooling load of the compressor can be improved.

According to the third aspect of the present invention, the discharge capacity can be reduced without causing a sudden increase in the temperature and pressure of the crank chamber, and the durability of the compressor can be further improved. Can be. You.

According to the fourth aspect of the present invention, when the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region exceeds a predetermined value, the pressure increase passage is opened by the pressure difference valve to reduce the discharge capacity. It can be surely reduced.

According to the fifth aspect of the present invention, when the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region exceeds a predetermined value, the pressure relief valve closes the pressure release passage, and The discharge capacity can be reliably reduced without causing a sudden increase in the temperature and pressure of the chamber.

[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 explanatory diagram related to generation of a moment in a capacity increasing direction.

FIG. 3 is a graph showing the relationship between the rotation speed of a drive shaft and each pressure.

FIG. 4 is a graph showing a change in each pressure when volume control is performed during high-speed rotation.

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

[Explanation of symbols]

Reference numeral 11 denotes a front housing forming a part of the housing, 12 denotes a cylinder block forming a part of the housing, 12a a cylinder bore, 13 ... a rear housing forming a part of the housing, 13a ... a suction chamber forming a suction pressure area. .., 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 ... Pressure passage, 25, 41 ... Capacity control valve, 30 ... Bleed passage, 31, 50 ... Differential pressure valve, 40 ... Bleed passage also serving as pressure release passage.

Continued on the front page (72) Mika Hori 2-1-1, Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation

Claims (5)

[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 is supported on the drive shaft so as to be integrally rotatable and swingable, and the difference between the pressure in the crank chamber and the pressure in the cylinder bore through the piston is determined based on the opening adjustment of the displacement control valve. In a variable displacement compressor in which the discharge pressure is changed and the displacement of the cam plate is controlled by changing the inclination angle of the cam plate in accordance with the differential pressure, a boost passage or a crank chamber that communicates the discharge pressure region with the crank chamber. One of the pressure release passages communicating the suction pressure region and the suction pressure region, when the differential pressure between the pressure in the crank chamber and the pressure in the suction pressure region becomes equal to or greater than a predetermined value, Variable capacity compressor provided with a differential pressure valve that operates to reduce capacitive output. 2. The capacity control valve is disposed in the middle of an air supply passage communicating the discharge pressure area with the crank chamber. The capacity control valve controls the supply amount of the refrigerant gas from the discharge pressure area to the crank chamber. 2. The variable displacement compressor according to claim 1, wherein the displacement is changed by adjusting the displacement. 3. The capacity control valve is disposed in the middle of a bleed passage communicating the crank chamber with the suction pressure area, and the capacity control valve controls the amount of refrigerant gas extracted from the crank chamber to the suction pressure area. The variable displacement compressor according to claim 1, wherein the displacement is changed by changing the discharge capacity. 4. The pressure differential valve is disposed in the middle of a pressure increasing passage.
The variable pressure valve according to any one of claims 1 to 3, wherein the pressure increasing passage is opened by the differential pressure valve when the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region becomes equal to or more than a predetermined value. Capacity compressor. 5. The pressure difference valve is disposed in the middle of a pressure release passage.
4. The variable valve according to claim 1, wherein when the pressure difference between the pressure in the crank chamber and the pressure in the suction pressure region exceeds a predetermined value, the bleed passage is closed by the pressure difference valve. Capacity compressor.