KR20060050781A - Control valve for variable displacement compressor - Google Patents

Abstract

An object of the present invention is to provide a control valve for a variable displacement compressor that can quickly recover to a predetermined discharge capacity without being hunted even when the rotation speed of the highly sensitive variable displacement compressor is rapidly changed.

In the valve unit 13 for controlling the flow rate of the refrigerant flowing from the discharge chamber to the crank chamber based on the differential pressure between the discharge pressure Pd and the suction pressure Ps, the pressure reducing unit 12 is provided in the high pressure port 18. When the pressure reduction piston 19 having a larger pressure receiving area than the valve member 23 receives a sudden change in the discharge pressure Pd, the differential pressure generated between the discharge pressure Pd and the pressure in the pressure adjusting chamber 20 is reduced. 23) acts in the opposite direction to the opening / closing direction and temporarily blunts the movement of the valve member 23 to be opened or closed by the differential pressure between the discharge pressure Pd and the suction pressure Ps, thereby making the variable highly sensitive. It recovers to a predetermined discharge capacity quickly without hunting a displacement compressor.

Valve member, pressure chamber, piston, high pressure port, control valve

Description

CONTROL VALVE FOR VARIABLE DISPLACEMENT COMPRESSOR

1 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a first embodiment.

2 is an explanatory view of the operation of a control valve for a variable displacement compressor when the rotational speed of the variable displacement compressor rapidly increases.

3 is a center longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a second embodiment;

4 is a center longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a third embodiment;

Fig. 5 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a fourth embodiment.

6 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a fifth embodiment;

FIG. 7 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a sixth embodiment; FIG.

FIG. 8 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a seventh embodiment; FIG.

FIG. 9 is a center longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to an eighth embodiment; FIG.

<Explanation of symbols for the main parts of the drawings>

11, 11a, 11b, 11c, 11d, 11e, 11f, 11g: control valve for variable displacement compressor

12: decompression unit

13 valve part

14: solenoid

15: body

16: cylinder

17: cover

18: high pressure port

19: decompression piston

20: pressure chamber

21: valve seat forming member

22, 31: shaft

23, 41: valve member

24: piston rod

25, 32, 43: spring

26: medium pressure port

27: low pressure port

28: bottomed sleeve

29: core

30: plunger

33: coil

34: harness

42: leaf spring

44: stopper

Pd: discharge pressure

Ps: suction pressure

Pc: pressure of the crankcase

[Patent 1] Japanese Patent Laid-Open No. 2001-132650 (paragraph number [0043] to [0045], FIG. 4)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control valve for a variable displacement compressor, and more particularly, for a variable displacement compressor installed in a variable displacement compressor constituting a refrigeration cycle of an automotive air conditioner so that its discharge capacity is controlled by the differential pressure between the discharge pressure and the suction pressure. Control valve.

The compressor used for compressing the refrigerant in the refrigeration cycle of the automotive air conditioner cannot control the rotation speed because the engine is used as the driving source. Therefore, in order to obtain appropriate cooling capability without being restricted by the rotational speed of the engine, a variable displacement compressor capable of changing the compression capacity of the refrigerant is used.

In such a variable displacement compressor, a compression piston is connected to a rocking plate attached to a shaft that is rotationally driven by an engine, and the discharge amount of the refrigerant is changed by changing the stroke of the compression piston by changing the angle of the rocking plate. .

The angle of the swinging plate is continuously changed by introducing a part of the refrigerant compressed into the sealed crank chamber, changing the pressure of the refrigerant to be introduced, and changing the balance of the pressure applied to both surfaces of the compression piston.

The pressure in the crank chamber is provided between the discharge chamber and the crank chamber of the variable displacement compressor or between the crank chamber and the suction chamber to change the flow rate of the refrigerant introduced into the crank chamber from the discharge chamber, or change the flow rate of the refrigerant drawn out from the crank chamber to the suction chamber. Control valves for variable displacement compressors, which are adapted to be adjusted by means of these, are known (see Patent Document 1, for example).

The control valve for variable displacement compressors described in Patent Document 1 has a valve portion disposed in the refrigerant passage between the discharge chamber and the crank chamber when mounted to the variable displacement compressor, and passes through an orifice provided between the crank chamber and the suction chamber to the discharge chamber. From the suction chamber to the refrigerant flow path is formed. The control valve for a variable displacement compressor includes a valve member which integrally comprises a valve member which receives the discharge pressure Pd in the valve opening direction, and a piston rod having a diameter substantially the same as the valve hole on the back side of the valve member. The end face of the piston rod is configured to receive a load of the solenoid which sets the discharge capacity by the suction pressure Ps and an external signal in the valve closing direction. Therefore, in this control valve for variable displacement compressors, the discharge pressure Pd and the suction pressure Ps are pressurized at both ends where the effective hydraulic pressure areas of the valve member and the piston rod are the same, so that the valves are controlled by their differential pressures Pd-Ps. The member opens and closes to control the flow rate of the refrigerant flowing from the discharge chamber to the crank chamber.

For example, when the engine speed increases, the speed of the variable displacement compressor increases, and the discharge capacity thereof increases, the discharge pressure Pd increases, the suction pressure Ps decreases, and their differential pressures Pd-Ps. Will grow. Then, since the valve lift of the valve portion operated by the differential pressures Pd-Ps increases, the control valve for the variable displacement compressor increases the flow rate of the refrigerant introduced into the crankcase, thereby increasing the pressure Pc of the crankcase, The discharge capacity of the filter is reduced so that the differential pressures Pd-Ps are reduced. That is, the control valve for the variable displacement compressor controls the flow rate of the refrigerant introduced into the crank chamber so that the variable displacement compressor maintains the differential pressures Pd-Ps between the discharge pressure Pd and the suction pressure Ps at a predetermined value. The predetermined value of the differential pressure can be set from the outside by the value of the current supplied to the solenoid.

The variable displacement compressor controlled by the control valve for the variable displacement compressor has a pressure in the crankcase due to a change in the differential pressure (Pd-Ps) as the rotational speed of the variable displacement compressor changes due to the change in the rotational speed of the engine and the discharge capacity thereof changes. Pc changes, whereby the inclination angle of the rocking plate changes, and the discharge capacity varies from maximum to minimum. For example, when the differential pressure (Pd-Ps) is 0 as in the start-up, the variable displacement compressor is operating at the maximum capacity. When the differential pressure (Pd-Ps) reaches a constant value, the variable capacity starts. There is individuality, and depending on the variable displacement compressor, the value of the differential pressure Pc-Ps of the pressure Pc in the crankcase and the suction pressure Ps at the time of starting variable displacement is wide. This is due to the ease of movement of the swing plate of the variable displacement compressor, i.e., the difference in sensitivity.

[Patent Document 1]

Japanese Patent Laid-Open No. 2001-132650 (paragraphs [0043] to [0045], FIG. 4)

However, the variable-capacity compressor with high sensitivity has a problem in that hunting is generated in response to a sudden change in pressure of the discharge pressure Pd and the suction pressure Ps caused by a sudden change in rotational speed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and the control valve for a variable displacement compressor capable of performing stable control without causing hunting even when there is a sudden pressure change caused by a sudden change in the engine speed for a highly sensitive variable displacement compressor. The purpose is to provide.

In the present invention, in order to solve the problem, the discharge capacity of the refrigerant by controlling the flow rate of the refrigerant flowing from the discharge chamber to the crank chamber by detecting the differential pressure of the discharge pressure of the discharge chamber and the suction pressure of the suction chamber of the variable capacity compressor In a control valve for a variable displacement compressor for changing the pressure, the pressure change caused by the sudden change in the rotational speed of the variable displacement compressor is sensed to slow down the opening and closing direction of the valve portion by a value proportional to the degree of pressure change. A control valve for a variable displacement compressor is provided, which includes a pressure reduction portion.

According to the control valve for the variable displacement compressor, the decompression unit does not sense the pressure change caused by the fluctuation of the variable revolution of the variable displacement compressor and performs the same operation as the conventional one, but reduces the pressure change due to the sudden change of the revolution. The addition is sensed and acts in the opposite direction to the opening and closing direction of the valve portion by a value proportional to the degree of pressure change, thereby slowing the movement of the valve portion. As a result, the variable-capacity compressor having high sensitivity can quickly recover to a predetermined discharge capacity without a sudden change in pressure when there is a sudden change in rotational speed.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to drawings.

1 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a first embodiment.

The control valve 11 for variable displacement compressor includes a pressure reducing unit 12 which detects a sudden pressure change in the discharge pressure Pd, and a pressure difference Pd-Ps between the discharge pressure Pd and the suction pressure Ps. The valve unit 13 which senses and controls the flow rate of the refrigerant flowing from the discharge chamber to the crank chamber and the solenoid 14 which can set a predetermined value of the differential pressure Pd-Ps to be controlled from the outside are on the same axis line. It is arranged in the configuration.

As for the body 15 which accommodates the pressure reduction part 12 and the valve part 13, the cylinder 16 is formed in the upper part of the figure, and the opening part of the upper end part is closed by the cover 17. As shown in FIG. In the lower position of the figure of the cylinder 16, when the control valve 11 for variable capacity compressors is attached to a variable capacity compressor, the high pressure port 18 which communicates with the discharge chamber is formed. In the cylinder 16, the decompression piston 19 is arrange | positioned so that advancing and retracting in the axial direction, and the space of the pressure control chamber 20 is formed in the upper part of the cylinder 16 with the body 15 and the cover 17. . This pressure control chamber 20 communicates with the high pressure port 18 via a predetermined gap between the cylinder 16 and the pressure reduction piston 19. The hole is formed in the center of the bottom part of the cylinder 16, and the cylindrical valve seat formation member 21 is press-fitted in the hole. The valve seat forming member 21 has a passage penetrating in the axial direction, that is, a valve hole, and the lower end of the figure constitutes the valve seat of the valve portion 13. Moreover, the shaft 22 is arrange | positioned in the valve hole by the valve seat formation member 21, and the one end part is being fixed to the pressure reduction piston 19. As shown in FIG.

The valve member 23 is arranged so that the valve hole can be opened and closed to face the valve seat by the valve seat forming member 21. The valve member 23 is integrally formed with the piston rod 24 whose one end is held in the axial direction by the shaft 22 and the body 15 fixed to the decompression piston 19. The outer diameter of the piston rod 24 is formed equally to the inner diameter of the valve hole of the valve seat forming member 21. The piston rod 24 is also pressurized by the spring 25 in the direction in which the valve member 23 falls from the valve seat forming member 21. In addition, the space in which the valve member 23 is disposed is a medium pressure port 26 that supplies the controlled pressure Pc to the crank chamber when the variable displacement compressor control valve 11 is mounted to the variable displacement compressor. The space in which the spring 25 is disposed is in communication with the low pressure port 27 which receives the suction pressure Ps of the suction chamber.

A hole is formed in the lower center of the figure of the body 15, and the opening protrusion of the bottomed sleeve 28 is closely coupled to this hole. In the bottomed sleeve 28, the core 29 and the plunger 30 of the solenoid 14 are provided. The core 29 is fixed to the bottom center hole and bottomed sleeve 28 of the body 15 by press fit. The plunger 30 is slidably disposed in the axial direction in the bottomed sleeve 28 and is fixed to one end of the shaft 31 which is disposed through the core 29 in the axial direction. The plunger 30 is further urged in the direction of the core 29 by the spring 32, and the other end of the shaft 31 is in contact with the lower end face of the drawing of the piston rod 24. A coil 33 is disposed on the outer circumference of the bottomed sleeve 28, and a harness 34 for feeding power is drawn outward.

In the control valve 11 for variable displacement compressor of the above structure, the spring 25 which presses the piston rod 24 of the valve part 13 to the direction of the solenoid 14 is the shaft 31 of the solenoid 14. Since the spring load is set larger than that of the spring 32 which presses) in the direction of the valve part 13, the valve part 13 forms the valve seat 23 when the solenoid 14 is non-energized. Since it is separated from the member 21, it is hold | maintained in the fully open state. At this time, the high pressure refrigerant of the discharge pressure Pd introduced into the high pressure port 18 from the discharge chamber of the variable capacity compressor flows from the medium pressure port 26 to the crank chamber through the fully open valve portion 13. Therefore, in the variable displacement compressor, the pressure Pc of the crankcase becomes a pressure close to the discharge pressure Pd, so that the operation of the discharge capacity is minimal.

When the vehicle air conditioner is activated or when the cooling load is maximum, the control current value supplied to the solenoid 14 becomes maximum. At this time, the plunger 30 is attracted to the core 29 with the maximum suction force, so that the piston rod 24 of the valve portion 13 is fixed to the plunger 30 against the pressing force of the spring 25. 31 is pressed by the valve closing direction, by which the valve member 23 seats on the valve seat formation member 21, and the valve part 13 will be in a fully closed state. At this time, since the high pressure refrigerant of the discharge pressure Pd introduced into the high pressure port 18 is blocked by the fully closed valve portion 13, in the variable displacement compressor, the pressure Pc of the crankcase is the suction pressure Ps. At a pressure close to, the maximum discharge capacity is performed.

Here, when the current value supplied to the solenoid 14 is set to a predetermined value, the valve member 23 is loaded with the spring 25 pressed in the valve opening direction and the solenoid 14 pressed in the valve closing direction. ), The discharge pressure Pd to receive water in the valve opening direction, and the suction pressure Ps to receive water in the valve closing direction are stopped at the valve lift position.

If the rotational speed of the variable capacity compressor is increased by increasing the rotational speed of the engine in such a balanced state and the discharged capacity is increased, the differential pressure (Pd-Ps) is increased because the discharge pressure (Pd) is increased and the suction pressure (Ps) is decreased. The force in the valve opening direction acts on the valve member 23 and the piston rod 24, and the valve member 23 lifts from the balance position to increase the flow rate of the refrigerant flowing from the discharge chamber to the crank chamber. Thereby, the pressure Pc of the crank chamber rises and the variable displacement compressor operates in the direction of decreasing its discharge capacity, so that the differential pressures Pd-Ps are controlled to be a predetermined value set by the solenoid 14. When the engine speed decreases, the reverse operation is performed, and the variable displacement compressor is controlled so that the differential pressures Pd-Ps become predetermined values set by the solenoid 14.

As described above, when the rotation speed of the variable displacement compressor fluctuates smoothly, such as when the vehicle is cruising at a constant speed, the decompression unit 12 does not sense the same operation as the conventional control valve for the variable displacement compressor. . Next, the operation of the variable displacement compressor control valve 11 in the case where the rotational speed of the variable displacement compressor suddenly changes due to the rapid change in the engine speed as in the case of rapid acceleration and deceleration of the automobile will be described.

2 is an explanatory view of the operation of a control valve for a variable displacement compressor when the rotational speed of the variable displacement compressor suddenly increases.

When the rotational speed of the variable displacement compressor is stably operating at 800 revolutions per minute, for example, the control valve 11 for the variable displacement compressor increases and discharges the discharge pressure Pd, The valve lift increases due to the drop in (Ps), which results in an increase in the pressure (Pc) of the crankcase, but in a highly sensitive variable displacement compressor, as indicated by the broken line in the figure, the valve lift, discharge pressure (Pd), and crank The pressure Pc and the suction pressure Ps of the yarn are overshooted, and the hunting phenomenon tends to occur.

At this time, the pressure reduction part 12 receives the pressure reduction piston 19 with which the water pressure area | region which is large enough to receive the discharge pressure Pd which increased rapidly than the valve member 23 is sufficient. On the other hand, since the pressure control chamber 20 is in the state of the pressure Pd (av) which is the average value of the discharge pressure Pd before it rapidly increases, the pressure reduction piston 19 has a valve portion (Pd-Pd (av)) by the differential pressure Pd-Pd (av) Force in the direction falling from 13) is generated. Since this force is transmitted to the valve member 23 via the shaft 22, the valve member 23 has the force obtained by subtracting the differential pressure [Pd-Pd (av)] of the depressurization portion 12 from the rapidly increasing discharge pressure Pd. Will be added. Thereby, as shown by the solid line in FIG. 2, since the valve lift becomes large more slowly, the control valve 11 for variable displacement compressors raises the pressure Pc of a crankcase more slowly. Thereafter, in the pressure reduction part 12, the rapidly increasing discharge pressure Pd is rapidly introduced into the pressure control chamber 20 through the gap between the cylinder 16 and the pressure reduction piston 19, whereby the differential pressure [Pd-Pd (av)] The function of the pressure reduction part 12 is lost here. That is, this pressure reduction part 12 has a function of detecting the sudden increase in the discharge pressure Pd and temporarily slowing the movement of the valve part 13 in the valve opening direction by a value proportional to the degree of pressure change. As a result, the control valve 11 for the variable displacement compressor can be quickly restored to a predetermined discharge capacity without hunting the variable displacement compressor.

The above is an operation in the case where the rotational speed of the variable capacity compressor has risen sharply, but the same applies to the case where the rotational speed drops rapidly. That is, when the rotation speed of the variable displacement compressor is sharply lowered, the differential pressure Pd (av) -Pd of the pressure reducing unit 12 is a force for moving the pressure reducing piston 19 in the direction of the valve unit 13, which is why the valve It becomes a force which pressurizes the valve member 23 which tries to move to a closing direction to a valve opening direction temporarily. As a result, the control valve 11 for the variable displacement compressor has a completely opposite operation to the case where the rotational speed of the variable displacement compressor suddenly increases even when the rotational speed suddenly decreases.

In the above configuration, the pressure reducing unit 19 is provided with a flow rate adjusting means such as a piston ring cut to a predetermined length in the circumferential direction and adjusts the size of the passage of the refrigerant entering and exiting the pressure control chamber 20. You may make it adjust the characteristic of (12).

3 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a second embodiment. In FIG. 3, components having the same or equivalent functions as those shown in FIG. 1 are denoted by the same reference numerals and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11a according to the second embodiment, the variable displacement compressor control valve 11 according to the first embodiment senses a sudden change in the discharge pressure Pd, The valve lift is controlled, whereas the valve lift of the valve unit 13 is controlled by detecting a sudden change in the pressure Pc supplied to the crank chamber.

For this reason, in the control valve 11a for variable displacement compressors which concerns on this 2nd Embodiment, the pressure reduction part 12 is arrange | positioned in the space which communicates with the intermediate pressure port 26, and the pressure reduction piston which receives a pressure Pc ( 19 is fixed to the piston rod 24 integral with the valve member 23. The valve seat forming member 21 has a flange portion, and the flange portion is fitted to the tip end opening portion in the upper portion of the figure of the body 15. In the downward position of the valve seat forming member 21, the pressure reducing piston 19 is loosely fitted so as to be able to move forward and backward in the axial direction, and a donut-shaped pressure adjusting chamber is formed by the flange portion of the body 15 and the valve seat forming member 21. The space of 20 is formed. In addition, the pressure reduction piston 19 has a concave upper portion thereof, and the concave portion is formed with a communication hole so as to communicate with the space communicated with the medium pressure port 26.

When the control valve 11a for variable displacement compressor of the above structure is controlled by a predetermined valve lift, when the discharge pressure Pd increases rapidly and the suction pressure Ps decreases rapidly, the valve member 23 and the piston rod The differential pressures Pd-Ps at both ends of 24 become large, and the valve lift is about to increase, whereby the pressure Pc on the downstream side of the valve portion 13 is also rapidly increased. At this time, since the pressure reduction piston 19 of the pressure reduction part 12 has a hydraulic pressure area that is sufficiently larger than that of the valve member 23, a force that temporarily tries to move upward in the drawing is generated in the pressure reduction piston 19. The force acts on the piston rod 24 fixed to the pressure reducing piston 19 in the valve closing direction. Therefore, since the force in the valve closing direction of the decompression piston 19 acts in the opposite direction to the valve member 23 which is trying to move in the valve opening direction by increasing the differential pressure Pd-Ps, the valve lift becomes gentle and accordingly The discharge pressure Pd and the pressure Pc of the crank chamber also slowly increase. Then, when the pressure of the pressure control chamber 20 is equal to the pressure Pc of the crank chamber, the discharge pressure Pd, the pressure Cc of the crank chamber, the suction pressure Ps, and the valve lift are quickly performed without overshooting. It will return to its original state. Of course, even when the rotational speed of the variable displacement compressor suddenly decreases, the control valve 11a for the variable displacement compressor similarly operates slowly, so that the variable displacement compressor can be quickly restored to a predetermined discharge capacity.

4 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a third embodiment. In Fig. 4, components having the same or equivalent functions as those shown in Fig. 1 are denoted by the same reference numerals and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11b according to the third embodiment, the variable displacement compressor control valve 11 according to the first embodiment senses a sudden change in the discharge pressure Pd, While the valve lift is controlled and the variable displacement compressor control valve 11a according to the second embodiment senses a sudden change in the pressure Pc supplied to the crank chamber, the valve lift of the valve unit 13 is controlled. Is different in that the valve lift of the valve unit 13 is controlled by detecting a sudden change in the suction pressure Ps.

For this reason, in this control valve 11b for variable displacement compressors, the spring 25 is arrange | positioned, and the pressure reduction piston 19 is arrange | positioned so that the space which communicates with the low pressure port 27, and the space which communicates with the solenoid 14 may be arrange | positioned. The decompression piston 19 is fixed to the piston rod 24 integral with the valve member 23. Therefore, in this variable displacement compressor control valve 11b, a space surrounded by the body 15, the pressure reducing piston 19, the piston rod 24, the core 29, and the shaft 31 is provided in the pressure control chamber. 20 is formed.

When the control valve 11b for variable displacement compressor of the above structure is controlled by a predetermined valve lift, when the discharge pressure Pd increases rapidly and the suction pressure Ps decreases rapidly, the valve member 23 and the piston rod The differential pressures Pd-Ps at both ends of the 24 become large, and the valve lift becomes large, whereby the suction pressure Ps decreases rapidly. At this time, since the decompression piston 19 of the decompression unit 12 has a pressure area larger than that of the valve member 23, the decompression piston 19 generates a force that tries to move upward in the drawing, and the force decompresses. The piston rod 24 fixed to the piston 19 acts in the valve closing direction. Since the force in the valve closing direction of the decompression piston 19 is applied to the valve member 23 in the reverse direction, the valve lift becomes gentle and the pressure rise of the discharge pressure Pd and the pressure Pc of the crank chamber is also gentle. After this, when the pressure in the pressure adjusting chamber 20 is equal to the suction pressure Ps, the discharge pressure Pd, the pressure of the crank chamber Pc, the suction pressure Ps, and the valve lift are quickly restored without overshooting. Will go back. Of course, even when the rotational speed of the variable displacement compressor suddenly decreases, the control valve 11b for the variable displacement compressor can operate quickly, and can quickly restore the variable displacement compressor to a predetermined discharge capacity.

5 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a fourth embodiment. In FIG. 5, components having the same or equivalent functions as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11c according to the fourth embodiment, in the variable displacement compressor control valve 11 according to the first embodiment, the pressure reduction unit 12 increases and decreases the discharge pressure Pd. While a sudden change in the direction is sensed to control the valve lift of the valve unit 13, a sudden change in the increase direction of the discharge pressure Pd is not sensed, but only a sudden change in the decrease direction of the discharge pressure Pd. This is sensitive in that it is sensitive to control the valve lift of the valve unit 13 is different.

That is, in this variable displacement compressor control valve 11c, the check valve for switching the sensitivity to the pressure reduction piston 19 constituting the pressure reduction unit 12 with respect to a sudden change between the increase direction and the decrease direction of the discharge pressure Pd. A valve mechanism (sensitivity switching means) is provided. This check valve mechanism forms a stepped passage so that the high pressure port 18 and the pressure adjusting chamber 20 communicate with the pressure reducing piston 19, and a ball-shaped valve member is provided in a large passage of the diameter on the pressure adjusting chamber 20 side. 41 is arrange | positioned and the leaf | plate spring 42 is latched by the opening edge part of the pressure control chamber 20 side so that the valve member 41 may not fall to the pressure control chamber 20 side.

When the control valve 11c for variable displacement compressor of the above structure is controlled by a predetermined valve lift, if the discharge pressure Pd increases rapidly, the pressure difference between the discharge pressure Pd and the pressure in the pressure regulator chamber 20 is reduced. As a result, the check valve mechanism provided in the decompression piston 19 immediately opens, and the pressure difference between the discharge pressure Pd and the pressure in the pressure regulator chamber 20 disappears. For this reason, the pressure reduction part 12 becomes insensitive, and the control valve 11c for variable displacement compressors responds sensitively to the sudden increase of discharge pressure Pd, and the valve part 13 abruptly opens the valve direction. In this way, the pressure Pc of the crankcase is increased more rapidly, thereby controlling the discharge capacity of the variable displacement compressor to be reduced quickly.

On the contrary, when the discharge pressure Pd drops rapidly, the pressure difference between the pressure Pd (av) in the pressure control chamber 20 which is the average value of the discharge pressure Pd that has dropped sharply and the discharge pressure Pd before it has dropped sharply. Since the check valve mechanism provided in the pressure reduction piston 19 is closed by this, the pressure reduction piston 19 which has a larger hydraulic pressure area than the valve member 23 detects the change of the discharge pressure Pd which fell rapidly. For this reason, the valve member 23 tries to act in the valve closing direction in response to the sudden drop in the discharge pressure Pd, but since the pressure reducing piston 19 acts in the valve opening direction instantaneously under rapid pressure change, the valve The movement of the valve closing direction of the member 23 is slowed down. That is, the variable valve compressor control valve 11c has a high sensitivity to a sudden change in the discharge pressure Pd and a low sensitivity to a change in the sudden drop direction of the discharge pressure Pd. Has characteristics. Thereby, for example, even if the variable displacement compressor responds excessively to the change in the direction of rapid increase in the discharge pressure Pd, and the discharge pressure Pd suddenly changes in the decrease direction, the direction in which the discharge pressure Pd decreases abruptly. Esau never responds excessively, so hunting does not occur.

6 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a fifth embodiment. In Fig. 6, the same components as those shown in Fig. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11d according to the fifth embodiment, the variable displacement compressor control valve 11c according to the fourth embodiment attaches the check valve mechanism of the pressure reduction unit 12 to the pressure reduction piston 19. The valve member of the check valve is composed of a ball member, whereas the check valve mechanism of the pressure reducing unit 12 is provided in the lid 17, and the valve member of the check valve is configured of a poppet valve. different.

That is, in the control valve 11d for the variable displacement compressor, the check valve mechanism provided in the depressurization section 12 opens the space in which the discharge pressure Pd is applied to the lid 17 of the decompression section 12 and the pressure regulator chamber 20. A stepped passage is formed so as to communicate with each other, and a mushroom-shaped valve member 41 is disposed in the large passage of the diameter on the pressure control chamber 20 side so that the valve member 41 does not fall to the pressure control chamber 20 side. The leaf spring 42 is latched to the opening end on the side of the pressure chamber 20, and a small amount of load for pressing the pressure reducing piston 19 in the direction away from the lid 17 between the lid 17 and the pressure reducing piston 19 is shown. It is comprised by arrange | positioning the spring 43.

The operation of the variable displacement compressor control valve 11d having the pressure reduction unit 12 having such a configuration is the same as that of the variable displacement compressor control valve 11c according to the fourth embodiment. Moreover, although the check valve mechanism is provided in the cover 17 of the pressure reduction part 12 in this 5th Embodiment, the body 15 which isolate | separates the pressure control chamber 20 from the side exposed to discharge pressure Pd is carried out. It may be installed in.

7 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a sixth embodiment. In FIG. 7, the same components as those shown in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11e according to the sixth embodiment, while the variable displacement compressor control valves 11c and 11d according to the fourth and fifth embodiments have a check valve mechanism, the discharge pressure ( It differs in that the sensitivity switching mechanism which switches a sensitivity when Pd) increases rapidly and falls rapidly.

That is, in this variable displacement compressor control valve 11e, the sensitivity switching mechanism provided in the pressure reducing section 12 switches the flowability of the refrigerant entering and exiting the pressure adjusting chamber 20, thereby reducing the outer circumferential shape of the pressure reducing piston 19. The outer diameter gradually increases from the side of the high pressure port 18 toward the pressure control chamber 20, and has a tapered shape. Therefore, the clearance gap of the outer periphery of the pressure reduction piston 19 constitutes the most throttled part in the upper end part of the figure in the pressure control chamber 20, and the flow path cross-sectional area is gradually expanded toward the space which communicates with the high pressure port 18 from it. . As a result, the cross-sectional area of the passage of the high pressure port 18 of the throttle portion is rapidly enlarged. When coolant flows from the throttle portion to the rapid expansion portion, axial flow is generated therein. When the pressure difference between the side and the inside of the pressure regulator chamber 20 is the same, the pressure reduction unit 12 is relatively lower than when the refrigerant entering the high pressure port 18 is gradually throttled and then passes through the throttle portion into the pressure regulator chamber 20. The coolant flow rate is smaller when the coolant in the pressure chamber 20 flows to the high-pressure port 18 side after being rapidly throttled in the throttle part.

When the rotational speed of the variable displacement compressor increases sharply and the discharge pressure Pd increases sharply, the pressure of the high pressure port 18 becomes high and the pressure in the pressure control chamber 20 before the high pressure increases. From the side of the pressure reducing piston 19, the refrigerant flows into the pressure adjusting chamber 20 from the side of the pressure reducing piston 19. On the contrary, when the rotation speed drops sharply and the discharge pressure Pd drops sharply, Refrigerant is going to flow to the high pressure port 18 side through the clearance of the outer periphery of the decompression piston 19. At this time, when the discharge pressure Pd increases rapidly and decreases rapidly, a difference occurs in the flow rate of the refrigerant flowing through the gap of the outer circumference of the pressure reduction piston 19, and when the discharge pressure Pd increases rapidly, the pressure regulator chamber 20 The pressure of) is short in time to become equal to the discharge pressure Pd, which has increased sharply, and when the discharge pressure Pd is sharply reduced, the pressure in the pressure regulator chamber 20 is increased to the discharge pressure Pd and equal pressure to which the pressure is rapidly increased. Longer When the discharge pressure Pd suddenly increases, the force in which the pressure reducing piston 19 acts on the valve member 23 of the valve portion 13 in the valve closing direction is reduced when the discharge pressure Pd decreases rapidly. Since 19 is smaller than the force which acts on the valve member 23 of the valve part 13 in the valve opening direction, when the discharge pressure Pd increases rapidly, the pressure reduction part 12 becomes insensitive and the valve part ( 13) does not decrease much. On the other hand, since the decompression piston 19 tends to move in the valve opening direction in the transition period in which the discharge pressure Pd decreases rapidly, the decompression portion 12 becomes more sensitive. As the pressure difference between the discharge pressure Pd and the suction pressure Ps decreases, the force that the valve portion 13 tries to act in the valve closing direction is temporarily canceled by the force that tries to act in the valve opening direction of the pressure reducing part 12. Therefore, the valve member 23 of the valve portion 13 is suppressed in the valve closing direction. As a result, since the valve part 13 does not respond excessively in the direction in which the discharge pressure Pd falls rapidly, a high-capacity variable displacement compressor causes the hunting phenomenon by the sudden pressure fluctuation of the discharge pressure Pd. none.

8 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to a seventh embodiment. In FIG. 8, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11a according to the second embodiment, in the variable displacement compressor control valve 11a according to the seventh embodiment, the direction in which the pressure reduction unit 12 is supplied to the crank chamber is increased. And control the valve lift of the valve unit 13 by detecting a sudden change in the decreasing direction, while not abruptly changing the increasing direction of the pressure Pc supplied to the crank chamber in the decreasing direction of the pressure Pc. It is different in that it controls the valve lift of the valve part 13 by sensing it sensitively only to a sudden change.

That is, in this control valve 11f for variable displacement compressors, the sensitivity is switched to the pressure reducing piston 19 constituting the pressure reducing unit 12 against a sudden change in the increase direction and the decrease direction of the pressure Pc supplied to the crankcase. The check valve mechanism for this is provided. This check valve mechanism forms a stepped passage so that the intermediate pressure port 26 and the pressure control chamber 20 communicate with the pressure reducing piston 19, and a ball-shaped valve member is provided in the passage having a large diameter on the pressure control chamber 20 side. The stopper 44 is fitted to the opening end of the pressure-control chamber 20 side so that the valve member 41 may not fall out in the pressure-control chamber 20 by arrange | positioning 41. As shown in FIG.

When the control valve 11f for variable displacement compressor having the above structure is controlled by a predetermined valve lift, the discharge pressure Pd increases rapidly so that the valve portion 13 operates in the valve opening direction and is supplied to the crank chamber. When Pc increases abruptly, the check valve mechanism provided in the decompression piston 19 immediately opens the valve by the pressure difference between the pressure Pc of the crank chamber and the pressure in the pressure control chamber 20. For this reason, since the pressure reduction part 12 does not affect the operation | movement of the valve part 13, the valve part 13 operates quickly in a valve opening direction in response to the rapid increase of the pressure Pc, and the pressure of the crank chamber ( By increasing Pc) more quickly, it is controlled in the direction of rapidly reducing the discharge capacity of the variable displacement compressor.

On the contrary, when the pressure Pc supplied to a crank chamber falls rapidly, the pressure of the intermediate pressure port 26 rather than the pressure Pc (av) in the pressure control chamber 20 which is an average value of the pressure Pc before it abruptly falls. Since Pc) becomes low, the check valve mechanism provided in the pressure reduction piston 19 is closed. For this reason, the pressure reduction piston 19 which has a hydraulic pressure area larger than the valve member 23 sensitively senses the sudden fall of the pressure Pc, and the pressure difference of the discharge pressure Pd and the suction pressure Ps becomes small, and a valve The portion 13 is momentarily suppressed in the valve closing direction by the pressure-reducing portion 12 which acts sensitively in the valve opening direction.

Thereby, the control valve 11f for variable displacement compressors has a high sensitivity to a change in the sudden increase direction of the pressure Pc supplied to the crankcase and a low sensitivity to a change in the sudden decrease direction of the pressure Pc. Since it becomes a valve opening characteristic, even if there exists a sudden change of the pressure Pc resulting from a sudden change of the discharge pressure Pd, it is not hunting.

FIG. 9 is a central longitudinal sectional view schematically showing a control valve for a variable displacement compressor according to an eighth embodiment. In Fig. 9, the same components as those shown in Fig. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the variable displacement compressor control valve 11b according to the eighth embodiment, in the variable displacement compressor control valve 11b according to the third embodiment, the pressure reduction unit 12 increases and decreases the suction pressure Ps. While the valve lift of the valve unit 13 is controlled by detecting a sudden change in the direction, a sudden change in the decreasing direction of the suction pressure Ps is not detected, but only for a sudden change in the increasing direction of the suction pressure Ps. This is sensitive in that it is sensitive to control the valve lift of the valve unit 13 is different.

That is, in this variable displacement compressor control valve 11g, a check valve for switching the sensitivity to the pressure reduction piston 19 constituting the pressure reduction unit 12 with respect to the sudden change in the increase direction and the decrease direction of the suction pressure Ps. The mechanism is installed. This check valve mechanism forms a stepped passage so that the low pressure port 27 and the pressure control chamber 20 are communicated with the pressure reducing piston 19, and a ball-shaped valve member is provided in the passage having a large diameter on the low pressure port 27 side. The stopper 44 is fitted to the opening end of the low pressure port 27 side so that the valve member 41 may be arrange | positioned and the valve member 41 will not fall out in the space which communicates with the low pressure port 27. As shown in FIG.

When the control valve 11g for variable displacement compressors having the above structure is controlled by a predetermined valve lift, when the suction pressure Ps decreases rapidly due to a rapid increase in the discharge pressure Pd, the pressure reducing piston 19 The installed check valve mechanism is immediately opened by the differential pressure between the suction pressure Ps and the pressure in the pressure regulator chamber 20. For this reason, since the pressure reduction part 12 does not affect the operation | movement of the valve part 13, the valve part 13 operates quickly in a valve opening direction in response to the sudden increase of discharge pressure Pd, and the pressure of a crankcase Control Pc to rise faster and reduce the discharge capacity of the variable displacement compressor quickly.

On the contrary, in the case where the suction pressure Ps rapidly increases due to the rapid decrease in the discharge pressure Pd, the pressure lower than the pressure Ps (av) in the pressure control chamber 20 which is the average value of the suction pressure Ps before the sudden increase. Since the suction pressure Ps of the port 27 becomes high, the check valve mechanism provided in the pressure reduction piston 19 is closed. Due to this, the decompression piston 19 sensitively senses a sudden increase in the suction pressure Ps, so that the valve portion 13 has an action in the valve closing direction by the decompression portion 12 which acts sensitively in the valve opening direction. It is momentarily suppressed.

Thus, the control valve 11g for the variable displacement compressor has a high sensitivity to a change in the sudden drop direction of the suction pressure Ps and a low sensitivity to a change in the sudden increase direction of the pressure Pc. There is no hunting.

In the control valve for variable displacement compressor of the present invention, when the variable displacement compressor receives a sudden change in the rotational speed, the pressure reducing unit senses a pressure change caused by the change in the rotational speed and the valve portion is proportional to the degree of the pressure change. Since the movement in the opening and closing direction is slowed down, there is an advantage that stable capacity control without hunting can be performed even when the variable-capacity compressor with high sensitivity is subjected to a sudden change in rotational speed.

Claims (13)

A control valve for a variable displacement compressor for varying the discharge capacity of the refrigerant by detecting a differential pressure between the discharge pressure of the discharge chamber of the variable capacity compressor and the suction pressure of the suction chamber and controlling the flow rate of the refrigerant flowing from the discharge chamber to the crank chamber. To And a pressure reducing unit for detecting a pressure change caused by a sudden change in the rotational speed of the variable displacement compressor and slowing down the movement of the valve unit by a value proportional to the degree of pressure change. valve. 2. The pressure reducing unit according to claim 1, wherein the pressure reducing unit is provided at a high pressure port through which the discharge pressure is introduced, and receives a pressure reduction piston for receiving the discharge pressure with a pressure receiving area larger than a valve member, and the discharge pressure and the pressure reduction piston for receiving the pressure reduction piston. And a shaft for transmitting the axial movement generated by the differential pressure of the pressure in the pressure control chamber closed by the pressure difference to the valve member via the valve hole. The variable shaft according to claim 2, wherein the shaft is integrally formed with the valve member for receiving the discharge pressure on one end face and the piston rod for receiving the suction pressure on the other end face. Control valve for displacement compressor. The sensitivity of claim 2, wherein the pressure reducing section has a force such that the pressure acting on the valve member via the shaft is made smaller than when the sudden decrease in the discharge pressure is at the time of a sudden increase in the discharge pressure. A control valve for a variable displacement compressor, further comprising a switching means. The pressure sensitive means according to claim 4, wherein the sensitivity switching means is provided in a passage formed through the pressure reducing piston so as to communicate the pressure chamber with the side of the high pressure port, and permits the flow of refrigerant from the side of the high pressure port toward the pressure chamber. And a check valve for blocking a flow of refrigerant from the pressure chamber to the side of the high pressure port. The said sensitivity switching means is provided in the passage formed so that the side which receives the discharge pressure and the said pressure control chamber may communicate with the member which forms the said pressure control chamber with the said pressure reduction piston, A control valve for a variable displacement compressor, characterized in that it is a check valve that blocks the flow of refrigerant from the side to the pressure control chamber and permits the flow of the refrigerant from the pressure chamber to the side receiving the discharge pressure. The said sensitivity switching means is comprised by forming the outer periphery of the said pressure reduction piston in taper shape so that the flow path cross section of the clearance gap formed in the outer periphery of the said pressure reduction piston may be gradually reduced toward the pressure control chamber from the side of the high pressure port. Control valve for a variable displacement compressor, characterized in that. 2. The pressure reducing unit according to claim 1, wherein the pressure reducing unit has a pressure reducing piston which is provided at a medium pressure port through which the control pressure controlled by the valve unit is led to the crank chamber, and which receives the control pressure with a hydraulic pressure area larger than that of the valve member. And a piston is configured to transmit the axial movement generated by the pressure difference between the control pressure at which the hydraulic pressure is received and the pressure in the pressure chamber closed by the pressure reducing piston to the valve member. The said pressure reduction part further has a sensitivity switching means which made the force which the said pressure reduction piston act on the said valve member to be smaller than when the abrupt increase of the control pressure is a sudden drop of the control pressure. The control valve for a variable displacement compressor characterized by the above-mentioned. 10. The method according to claim 9, wherein the sensitivity switching means is provided in a passage formed through the pressure reducing piston so as to communicate the pressure control chamber with the side of the medium pressure port, and permits the flow of refrigerant from the side of the medium pressure port toward the pressure control chamber. And a check valve for blocking the flow of the refrigerant from the pressure chamber to the side of the medium pressure port. 2. The pressure reducing unit according to claim 1, wherein the pressure reducing unit has a pressure reducing piston which is provided at a low pressure port into which the suction pressure is introduced, and receives the suction pressure with a hydraulic pressure area larger than that of the valve member. A control valve for a variable displacement compressor, characterized in that for transmitting to the valve member the axial movement generated by the differential pressure of the pressure in the pressure control chamber closed by the pressure reducing piston. The said pressure reduction part further has a sensitivity switching means which made the force which the said pressure reduction piston act on the said valve member to be larger than when the abrupt increase of the suction pressure is larger than the abrupt decrease of the suction pressure. The control valve for a variable displacement compressor characterized by the above-mentioned. 13. The pressure reducing means according to claim 12, wherein the sensitivity switching means is provided in a passage formed through the pressure reduction piston so as to communicate the side of the low pressure port with the pressure control chamber, and permits the flow of refrigerant from the side of the low pressure port toward the pressure control chamber. And a check valve for blocking the flow of the refrigerant from the pressure chamber to the side of the low pressure port.

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