JP4046530B2 - Capacity control valve for variable capacity compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacity control valve for a variable capacity compressor, and more particularly to a capacity control valve for a variable capacity compressor used in a variable capacity compressor that compresses refrigerant gas in a refrigeration cycle of an automotive air conditioner.
[0002]
[Prior art]
Since the compressor used for compressing the refrigerant in the refrigeration cycle of the air conditioner for automobiles uses the engine as a drive source, the rotational speed control cannot be performed. Therefore, in order to obtain an appropriate cooling capacity without being restricted by the engine speed, a variable capacity compressor capable of changing the compression capacity of the refrigerant is used.
[0003]
In such a variable capacity compressor, a piston for refrigerant compression is connected to a swing plate attached to a shaft that is rotationally driven by an engine, and the stroke of the piston is changed by changing the angle of the swing plate. The discharge capacity of the compressor is changed.
[0004]
The angle of the oscillating plate is continuously changed by introducing a part of the compressed refrigerant into the sealed crank chamber to change the pressure in the crank chamber and changing the balance of pressure applied to both end faces of the piston. ing. The capacity control valve for the variable capacity compressor controls the introduction amount of the compressed refrigerant.
[0005]
For example, in a compression capacity control device described in Japanese Patent Application Laid-Open No. 2001-132650, an electromagnetically controlled variable capacity compressor capacity control valve is provided between a discharge chamber and a crank chamber of a compressor or between a crank chamber and a suction chamber. I have. This capacity control valve for a variable capacity compressor is controlled to communicate or close so as to keep a differential pressure between the pressure in the discharge chamber and the crank chamber or a differential pressure between the pressure in the discharge chamber and the pressure in the suction chamber at a predetermined value. The predetermined value of the differential pressure to be controlled can be set from the outside by the current value of the solenoid. As a result, when the engine speed increases, the pressure introduced into the crank chamber can be increased to reduce the compression capacity, and when the engine speed decreases, the pressure introduced into the crank chamber can be decreased and compressed. The capacity is increased so that the amount of refrigerant discharged from the compressor does not change due to fluctuations in the engine speed.
[0006]
[Problems to be solved by the invention]
However, in the conventional capacity control valve for a variable capacity compressor, when the operation capacity of the compressor is to be minimized, it is necessary to maximize the amount of refrigerant introduced into the crank chamber. If it is small, the amount of refrigerant to be introduced is small, so it takes time to shift to the minimum operation, and the controllability may deteriorate.
[0007]
Therefore, if the size of the valve is increased in order to increase the amount of refrigerant introduced, the pressure receiving area of the valve also increases, so that a large solenoid force is required to control the valve. As a result, the solenoid becomes larger. There was a problem that it led to cost increase.
[0008]
The present invention has been made in view of these points, and provides a displacement control valve for a variable displacement compressor that can operate without requiring a large solenoid force even if the valve size is increased. Objective.
[0009]
[Means for Solving the Problems]
In order to solve the above problem, the present invention controls the amount of refrigerant introduced from the discharge chamber into the crank chamber so as to keep the differential pressure between the suction chamber pressure and the discharge chamber pressure at a predetermined differential pressure. In a capacity control valve for a variable capacity compressor that changes a discharge capacity of a refrigerant from a compressor, the variable capacity compressor is disposed so as to be seated from a side of the crank chamber between refrigerant passages communicating with the discharge chamber and the crank chamber. a valve body for opening and closing the refrigerant passage, have a smaller pressure receiving area than the effective pressure receiving area of the valve body with one end extend in the axial direction of the valve body is fixed to the valve body through the valve hole, A first piston rod formed integrally with the valve body; and coaxially disposed adjacent to the valve body, having the same pressure receiving area as an effective pressure receiving area of the valve body, and the valve body The suction pressure of the suction chamber at the end opposite to the side of A displacement control valve for a variable displacement compressor is provided, comprising: a second piston rod that receives the pressure and a solenoid portion that applies a solenoid force corresponding to the predetermined differential pressure to the valve body. Is done.
[0010]
According to such a capacity control valve for a variable capacity compressor, the valve body having a large pressure receiving area and a discharge pressure applied in the valve opening direction, and the first piston rod having a small pressure receiving area and a discharge pressure applied in the valve closing direction, By providing the above, it is possible to configure a valve having a small operating force corresponding to the difference in pressure receiving area despite the large valve size. Thereby, the solenoid force for setting the differential pressure value to be controlled may be small, so that the capacity control valve can be downsized.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a variable capacity compressor to which a capacity control valve according to the present invention is applied.
[0012]
The variable capacity compressor has a crank chamber 1 formed in an airtight manner, and has a rotary shaft 2 that is rotatably supported therein. One end of the rotary shaft 2 extends to the outside of the crank chamber 1 through a shaft seal device (not shown), and a pulley 3 is fixed to the end portion. A driving force is transmitted to the pulley 3 from the output shaft of the engine via a clutch and a belt. The rotating shaft 2 is provided with a swing plate 4 with a variable inclination angle. Around the axis of the rotary shaft 2, a plurality (one in the illustrated example) of cylinders 5 are arranged. Each cylinder 5 is provided with a piston 6 that converts the rotational movement of the swing plate 4 into a reciprocating movement. Each cylinder 5 is connected to a suction chamber 9 and a discharge chamber 10 via a suction relief valve 7 and a discharge relief valve 8, respectively. The suction chamber 9 of each cylinder 5 communicates with each other to form one chamber, and is connected to the evaporator of the refrigeration cycle. The discharge chambers 10 of the respective cylinders 5 are also communicated with each other into one chamber, and are connected to a gas cooler or a condenser of the refrigeration cycle.
[0013]
This variable capacity compressor is also provided with a capacity control valve 11 having a valve for controlling the flow rate of the refrigerant in the middle of the refrigerant flow path from the discharge chamber 10 to the crank chamber 1. Orifices 12 and 13 are respectively provided between the crank chamber 1 and the suction chamber 9.
[0014]
In the variable capacity compressor configured as described above, when the rotary shaft 2 rotates by the driving force of the engine and the swing plate 4 provided on the rotary shaft 2 rotates, the piston 6 connected to the swing plate 4 reciprocates. As a result, the refrigerant in the suction chamber 9 is sucked into the cylinder 5 and compressed in the cylinder 5, and the compressed refrigerant is discharged into the discharge chamber 10.
[0015]
At this time, during normal operation, the capacity control valve 11 receives the refrigerant discharge pressure Pd in the discharge chamber 10 and keeps the differential pressure with the suction pressure Ps in the suction chamber 9 at a predetermined differential pressure. The amount of refrigerant introduced into the chamber 1 is controlled. As a result, the pressure Pc in the crank chamber 1 is maintained at a predetermined value, and the capacity of the cylinder 5 is controlled to a predetermined value.
[0016]
In the maximum operation, the capacity control valve 11 operates so as to close the refrigerant flow path from the discharge chamber 10 to the crank chamber 1, but further from the discharge chamber 10 to the crank chamber 1 through the orifice 12. Since there is a circulation path through which a minute refrigerant flows from the chamber 1 through the orifice 13 to the suction chamber 9, lubricating oil mixed in the refrigerant can be supplied to the crank chamber 1, and the piston 6 is seized. A compressor failure is avoided.
[0017]
Next, the capacity control valve 11 according to the present invention will be described in detail.
FIG. 2 is a central longitudinal sectional view showing the structure of the capacity control valve.
This capacity control valve 11 is formed in the upper body 20, one having a large-diameter valve body 21 disposed in a refrigerant passage communicating with the discharge chamber 10 and the other communicating with the crank chamber 1. . The valve body 21 faces the valve seat 22 formed in the upper body 20 from the side of the space communicating with the crank chamber, and is biased by a spring 23 in a direction away from the valve seat 22. The valve body 21 is also integrally formed with a piston rod 24 extending in the axial direction via the valve hole 22a . The piston rod 24 has a diameter smaller than the diameter of the valve seat 22, and is disposed so as to be able to advance and retract in the axial direction through the upper body 20. The upper body 20 is formed with a passage 25 extending in parallel with the axis thereof, and has a space closed by a plate 26 at the upper end in the figure. Thereby, the upper end surface of the piston rod 24 receives the pressure Pc of the crank chamber.
[0018]
The upper body 20 is press-fitted into the upper opening of the intermediate body 27, and a strainer 28 is attached to the upper edge of the upper body 20 so as to cover the upper body 20. Two piston rods 29 and 30 having different diameters are disposed at the axial position of the intermediate body 27 so as to be capable of moving forward and backward in the axial direction. The upper piston rod 29 has the same diameter as that of the valve seat 22, and the upper end of the piston rod 29 is in contact with the valve body 21. The lower piston rod 30 has the same diameter as the piston rod 24 formed integrally with the valve body 21. The connecting portions of these piston rods 29 and 30 have a reduced diameter and constitute a space communicating with the suction chamber. The intermediate body 27 is formed with a passage 31 extending parallel to the axis thereof.
[0019]
The intermediate body 27 is screwed into the upper opening of the lower body 32. The upper ends of the fixed iron core 33 and the sleeve 34 of the solenoid unit 50 are fixed to the central opening of the lower body 32. The upper part of the central opening of the fixed iron core 33 is screwed to the lower part of the intermediate body 27. The threaded portion of the fixed iron core 33 has a passage 35 that is drilled in parallel to the axis and formed in a radial direction so as to connect the space in which the valve body 21 is accommodated and the interior of the solenoid unit 50. I try to communicate.
[0020]
A guide 37 for holding the upper end of the shaft 36 of the solenoid unit 50 slidably in the axial direction is provided in the central opening of the fixed iron core 33. The lower end portion of the shaft 36 is held slidable in the axial direction by a guide 39 provided on a stopper 38 that closes the lower end portion of the sleeve 34. The upper end portion of the shaft 36 is in contact with the lower piston rod 30.
[0021]
The movable iron core 40 of the solenoid unit 50 is fitted to the lower part of the shaft 36. The movable iron core 40 is restricted from moving upward by an E-type retaining ring 41 fitted into the shaft 36. A spring 42 is disposed between the movable iron core 40 and the fixed iron core 33, and a spring 43 is disposed between the movable iron core 40 and the stopper 38 on the opposite side. An electromagnetic coil 44 and a yoke 45 are disposed on the outer periphery of the sleeve 34.
[0022]
When the displacement control valve 11 is mounted on a variable displacement compressor, the portion between the portion communicating with the discharge chamber 10 and receiving the discharge pressure Pd and the portion communicating with the crank chamber 1 and receiving the pressure Pc are sealed. In addition, an O-ring 46 is provided around the intermediate body 27. The lower body 32 communicates with the suction chamber and an O-ring 47 for sealing between a portion communicating with the crank chamber 1 and receiving the pressure Pc and a portion communicating with the suction chamber and receiving the suction pressure Ps. An O-ring 48 for sealing between a portion that receives the suction pressure Ps and the solenoid unit 50 is provided. Furthermore, an O-ring 49 is also provided between the lower body 32 and the fixed iron core 33 to seal between the pressure Pc of the crank chamber 1 in the solenoid unit 50 and the suction pressure Ps.
[0023]
The pressure Pc in the crank chamber 1 is introduced into the space below the piston rod 30 via the passage 31 of the intermediate body 27 and the passage 35 of the lower body 32, and this pressure Pc is further applied to the solenoid portion 50 . The inside is full. Since the inside of the sleeve 34 is equalized by the pressure Pc, the pressure Pc does not affect the operation of the movable iron core 40.
[0024]
Here, the pressure relationship in the capacity control valve 11 will be described. First, the discharge pressure Pd of the refrigerant introduced from the discharge chamber 10 is applied to the valve body 21 and the piston rod 24 in the opposite axial direction. When the effective pressure receiving area of the valve body 21 is A and the effective pressure receiving area of the piston rod 24 is B, a force of Pd · A acts on the valve body 21 in the downward direction in the figure, and the piston rod 24 has an upward direction in the figure. Pd · B force works in the direction. Since the effective pressure receiving area A of the valve body 21 and the effective pressure receiving area B of the piston rod 24 are in a relationship of A> B, the valve body 21 and the piston rod 24 exert a force Pd ( A-B) works. This difference (A−B) corresponds to the effective pressure receiving area of the conventional valve body, and conventionally, the effective pressure receiving area limits the amount of refrigerant flowing. However, in the present invention, although it has a large effective pressure receiving area of A and the amount of refrigerant can be increased, the force acting in the valve opening direction with respect to the valve body 21 is referred to as Pd (AB). It becomes a small power. Moreover, the pressure Pc in the crank chamber 1 is, on the one hand, a downward force Pc · B acting on the piston rod 24 via the passage 25, and on the other hand, the piston rod having the same diameter as the piston rod 24 via the passage 31. Since the upward force Pc · B acts on the valve 30, the influence of the pressure Pc on the valve body 21 is cancelled. Thus, although the valve body 21 is large, the valve body 21 can constitute a valve having a substantially small pressure receiving area (AB).
[0025]
The piston rod 29 in contact with the valve body 21 has the same diameter as that of the valve seat 22, and the pressure receiving area for receiving the suction pressure Ps is A. Directional force Ps · A is working. Therefore, the valve body 21 that controls the flow rate of the refrigerant flowing from the discharge chamber 10 to the crank chamber 1 constitutes a differential pressure valve that operates by feeling the differential pressure between the discharge pressure Pd and the suction pressure Ps.
[0026]
In the capacity control valve 11 described above, when the control current is not supplied to the electromagnetic coil 44 of the solenoid unit 50 , the discharge pressure Pd pushes the valve body 21 open as shown in FIG. It is. Therefore, the pressure Pc in the crank chamber 1 becomes a value close to the discharge pressure Pd, the pressure difference applied to both surfaces of the piston 6 becomes the smallest, and the swinging plate 4 has an inclination angle at which the stroke of the piston 6 becomes the smallest. Therefore, the variable capacity compressor is operated at the minimum capacity.
[0027]
When the maximum control current is supplied to the electromagnetic coil 44 of the solenoid unit 50 , the movable iron core 40 is attracted to the fixed iron core 33 and moves upward in the figure, and the valve body 21 is fully closed. As a result, the refrigerant in the crank chamber 1 flows to the suction chamber 9 through the orifice 13, the pressure Pc in the crank chamber 1 decreases to a value close to the suction pressure Ps in the suction chamber 9, and the pressure difference applied to both surfaces of the piston 6 is reduced. At the maximum, the swinging plate 4 has an inclination angle at which the stroke of the piston 6 is maximized, and the variable capacity compressor shifts to the maximum capacity operation.
[0028]
In the case of normal control in which a predetermined control current is supplied to the electromagnetic coil 44 of the solenoid unit 50 , the movable iron core 40 is attracted to the fixed iron core 33 in accordance with the magnitude of the control current and is shown in the figure. A force that moves upward is generated. This force becomes a set value of the valve body 21 that operates as a differential pressure valve. Therefore, the capacity control valve 11 senses the differential pressure between the discharge pressure Pd and the suction pressure Ps and maintains the differential pressure at a value set by the solenoid unit 50 from the discharge chamber 10 to the crank chamber. 1 to operate so as to control the flow rate of the refrigerant flowing to 1.
[0029]
【The invention's effect】
As described above, according to the present invention, a valve body having a large pressure receiving area and a piston rod having a small pressure receiving area are formed integrally with each other to form a valve having a magnitude of a difference between the pressure receiving areas, and a crank chamber. The configuration is designed to cancel the effects of pressure. Since the valve size can be increased, the flow rate of refrigerant flowing from the discharge chamber to the crank chamber can be increased, and the substantial pressure receiving area can be set small regardless of the valve size, so the solenoid force can be small. As a result, the capacity control valve can be reduced in size.
[0030]
Further, if the difference in pressure receiving area between the integrally formed valve body and the piston rod is the same, a valve of any size can be freely made while using the same solenoid unit 50 , so that the applied variable capacity It is easy to make a valve size that sets an appropriate refrigerant introduction amount according to the characteristics of the compressor, and versatility can be provided.
[0031]
Furthermore, there is no influence of the pressure in the crank chamber, the valve body moves purely by the difference between the discharge pressure and the suction pressure to control the flow rate, and these discharge pressure and suction pressure are respectively formed integrally with the valve body. The difference in pressure receiving area between the piston rod and the pressure receiving area between the two integrally formed piston rods, so that the operating pressure of the refrigeration cycle is very high, for example, when carbon dioxide is used as the refrigerant. It can be effectively applied to a variable capacity compressor.
[Brief description of the drawings]
FIG. 1 is a sectional view schematically showing a variable capacity compressor to which a capacity control valve according to the present invention is applied.
FIG. 2 is a central longitudinal sectional view showing the structure of a capacity control valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Crank chamber 2 Rotating shaft 3 Pulley 4 Swing plate 5 Cylinder 6 Piston 7 Suction relief valve 8 Discharge relief valve 9 Suction chamber 10 Discharge chamber 11 Capacity control valve 12, 13 Orifice 20 Upper body 21 Valve body 22 Valve seat
22a Valve hole 23 Spring 24 Piston rod 25 Passage 26 Plate 27 Intermediate body 28 Strainer 29, 30 Piston rod 31 Passage 32 Lower body 33 Fixed iron core 34 Sleeve 35 Passage 36 Shaft 37 Guide 38 Stopper 39 Guide 40 Movable iron core 41 E type Retaining ring 42, 43 Spring 44 Electromagnetic coil 45 Yoke 46, 47, 48, 49 O-ring
50 Solenoid part

Claims (2)

The refrigerant discharge capacity from the variable capacity compressor is changed by controlling the amount of refrigerant introduced from the discharge chamber into the crank chamber so that the differential pressure between the suction chamber pressure and the discharge chamber pressure is maintained at a predetermined differential pressure. In capacity control valve for variable capacity compressor,
A valve body that is disposed so as to be seated from the crank chamber side between the refrigerant passages communicating with the discharge chamber and the crank chamber, and opens and closes the refrigerant passage;
Have a smaller pressure receiving area than the effective pressure receiving area of the valve body with one end extend in the axial direction of the valve body is fixed to the valve body through the valve hole is formed in the valve body and integral A first piston rod;
The valve body is arranged coaxially and has the same pressure receiving area as the effective pressure receiving area of the valve body, and the suction pressure of the suction chamber is applied to the end opposite to the valve body side. A second piston rod to receive,
A solenoid unit that applies a solenoid force corresponding to the predetermined differential pressure to the valve body;
A capacity control valve for a variable capacity compressor. A third piston rod extending in the axial direction of the valve body and having one end fixed to the second piston rod and having the same pressure receiving area as the first piston rod; The other end and the other end of the third piston rod receive the crank chamber pressure in opposite axial directions to cancel the influence of the crank chamber pressure, and the third piston rod The capacity control valve for a variable capacity compressor according to claim 1, wherein the capacity control valve is formed integrally with the second piston rod.

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