JP4173073B2 - Control valve for variable capacity compressor - Google Patents

Description

  The present invention relates to a control valve for a variable capacity compressor, and more particularly to a control valve for a variable capacity compressor used to control the discharge capacity of a variable capacity compressor constituting a refrigeration cycle of an automotive air conditioner.

  Since the compressor used for compressing the refrigerant in the refrigeration cycle of the automotive air conditioner uses the engine as a drive source, it cannot perform the rotational speed control. 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.

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

  The angle of the swing plate is continuously increased by introducing a part of the compressed refrigerant into the sealed crank chamber, changing the pressure of the introduced refrigerant, and changing the balance of pressure applied to both sides of the compression piston. Is changing.

  For the pressure in the crank chamber, a control valve is provided between the discharge chamber and the crank chamber of the variable capacity compressor or between the crank chamber and the suction chamber to change the flow rate of the refrigerant introduced from the discharge chamber into the crank chamber, or It is adjusted by changing the flow rate of the refrigerant led out from the chamber to the suction chamber. For example, the control valve described in Patent Document 1 is disposed between a discharge chamber and a crank chamber of a variable capacity compressor, and an orifice is provided between the crank chamber and the suction chamber so that refrigerant is transferred from the discharge chamber to the suction chamber. The control valve is integrally provided with a piston rod having substantially the same diameter as the valve hole on the back side of the valve body that receives the discharge pressure (Pd) in the valve opening direction, and is closed to the end surface of the piston rod. It is configured to receive suction pressure (Ps) and solenoid force in the valve direction. The control valve communicates with the crank chamber of the variable capacity compressor through a space downstream of the valve body, that is, a space provided around a connection portion between the valve body and the piston rod. As a result, the control valve communicates or closes the passage between the discharge chamber and the crank chamber so as to maintain the pressure difference (Pd−Ps) between the discharge pressure (Pd) and the suction pressure (Ps) at a predetermined value. By controlling, the predetermined value of the differential pressure can be set from the outside by the value of the current supplied to the solenoid. As a result, when the engine speed increases, the pressure (Pc) introduced into the crank chamber is increased to reduce the discharge capacity, and when the engine speed decreases, the orifice is made larger than the refrigerant flow rate introduced into the crank chamber. Thus, the flow rate released to the suction chamber is increased and the pressure (Pc) in the crank chamber is decreased to increase the discharge capacity, thereby keeping the discharge capacity of the variable capacity compressor constant.

At this time, the control valve receives the discharge pressure (Pd) from the upstream side, and the downstream side is the pressure (Pc) to be supplied to the crank chamber of the variable capacity compressor. At that time, the valve body receives pressure (Pc) in the valve closing direction, and the piston rod integrated with the valve body receives pressure (Pc) in the valve opening direction of the valve body. Since the inner diameter of the valve hole and the outer shape of the piston rod are substantially the same, the same pressure (Pc) is applied to the valve body and the piston rod in the opposite direction. (Pc) is canceled, and the control valve is controlled to open and close by the pressure difference (Pd−Ps) between the discharge pressure (Pd) and the suction pressure (Ps).
JP 2001-132650 A (paragraph numbers [0043] to [0045], FIG. 4)

  In the conventional control valve for a variable capacity compressor, when the variable capacity compressor is to be operated in the minimum operation in which the discharge capacity is minimized, it is necessary to maximize the flow rate of the refrigerant introduced into the crank chamber. However, if the size of the control valve is small at that time, the flow rate of the introduced refrigerant is small, so it takes time to shift to the minimum operation, the controllability deteriorates, or there is a case where it is not possible to shift to the minimum operation due to insufficient flow rate. . In addition, if the valve size is increased to increase the flow rate of the introduced refrigerant, the pressure receiving area of the valve body increases, so a large solenoid force is required in the direction against the discharge pressure, and the coil is increased in size. There was a problem that this led to an increase in cost.

  The present invention has been made in view of the above points, and has a variable capacity that can be operated without requiring a large solenoid force while increasing the valve size to increase the refrigerant flow rate and shorten the minimum operation transition time. It aims at providing the control valve for compressors.

In order to solve the above problem, the present invention controls the flow rate of refrigerant introduced from the discharge chamber into the crank chamber so as to keep the differential pressure between the suction pressure of the suction chamber and the discharge pressure of the discharge chamber at a predetermined value. In the control valve for a variable capacity compressor that changes the discharge capacity of the refrigerant from the compressor, the control valve 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. A valve body that opens and closes the refrigerant passage, and has a pressure receiving area smaller than that of the valve body. One end is fixed to the valve body through a valve hole and receives the discharge pressure, and the other end is led to the crank chamber. A piston rod that receives the pressure to be transmitted through the passage communicating with the refrigerant passage on the side communicating with the crank chamber, and a pressure receiving area equal to the difference between the pressure receiving area of the valve body and the pressure receiving area of the piston rod , One end A shaft that receives the pressure introduced into the crank chamber by contacting the body and receiving the suction pressure at the other end, and a solenoid force corresponding to the differential pressure of the predetermined value is applied to the valve body via the shaft. A control valve for a variable displacement compressor, comprising: a solenoid;

  According to such a control valve for a variable capacity compressor, the pressure receiving area of the valve body for receiving the discharge pressure and the pressure receiving area of the piston rod are made different, and the suction pressure is received by the shaft having the pressure receiving area of the difference. Therefore, even if the size of the valve is increased to increase the flow rate of refrigerant flowing at the time of transition to the minimum operation, the substantial pressure receiving area applied to the valve body can be reduced, so that the solenoid force for controlling the valve body can be reduced. Can be miniaturized.

  The control valve for a variable displacement compressor according to the present invention can reduce the pressure receiving area regardless of the size of the valve, so that the solenoid force is small, and therefore there is an advantage that the size can be reduced even if the valve size is increased. . Further, since the size of the valve can be arbitrarily set, versatility can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a central longitudinal sectional view showing a control valve for a variable capacity compressor according to the present invention.
The control valve 11 for the variable capacity compressor has a valve seat forming member 13 press-fitted into the opening at the front end of the body 12, and a hole constituting the valve hole and a cylinder having a smaller diameter than the hole are formed at the center thereof. Are arranged on the same axis. The valve seat forming member 13 is formed on its side with a passage 14 that communicates with a hole constituting the valve hole and introduces a refrigerant having a discharge pressure Pd from the discharge chamber of the variable capacity compressor into the valve hole. The part is formed with a passage 15 extending in parallel with the axis thereof, and the outer opening end of the valve seat forming member 13 is closed by a plate.

The body 12 is formed with a passage 16 that leads to a controlled pressure Pc in communication with the crank chamber of the variable capacity compressor, and is formed between the passage 16 and the valve hole of the valve seat forming member 13. In the space, a valve body 18 is disposed so as to be able to contact and separate from the valve seat 17 of the valve seat forming member 13. The valve body 18 is coupled to a piston rod 19 slidably disposed on a cylinder of the valve seat forming member 13 by a small diameter shaft. Preferably, the valve body 18, the small diameter shaft and the piston rod 19 are integrated. Is formed. Further, the valve element 18 is urged in a direction Ru away from the valve seat 17 by the spring 20. A strainer 21 is attached to the outer end opening of the body 12.

  The body 12 is formed with a passage 22 that communicates with the suction chamber of the variable capacity compressor and receives the suction pressure Ps, and holds the shaft 23 slidably on the same axis as the valve body 18 and the piston rod 19. . The shaft 23 has a cross-sectional area corresponding to the difference between the cross-sectional area of the valve hole and the cross-sectional area of the piston rod 19, and one end thereof is in contact with the valve body 18.

  The body 12 is fixed to the body 24 of the solenoid. One end of a solenoid sleeve 25 is fixed to the central opening of the body 24, and a fixed iron core 26 of the solenoid is fixed to the body 12. The other end of the sleeve 25 is closed by a stopper 27, and a guide 28 is provided inside thereof. The guide 28 is for holding one end of a shaft 29 that penetrates the fixed iron core 26 and is disposed so as to be able to advance and retreat in the axial direction. The other end of the shaft 29 is held by the body 12, and The shaft 23 is in contact with the other end. The movable iron core 30 is fixed to the shaft 29 of the solenoid between the guide 28 and the fixed iron core 26. The movable iron core 30 is also provided with a spring 31 between the fixed iron core 26 and a spring 32 between the opposite guide 28. A coil 33 and a yoke 34 are disposed on the outer periphery of the sleeve 25. The solenoid sleeve 25 communicates with the suction chamber of the variable capacity compressor via the passage 22 of the body 12 and is filled with the suction pressure Ps. It does not affect the operation.

  Here, the pressure relationship in the variable displacement compressor control valve 11 will be described. First, the refrigerant discharge pressure Pd introduced from the discharge chamber of the variable capacity compressor is applied to the valve body 18 and the piston rod 19 in the opposite axial direction. Assuming that the pressure receiving area of the valve body 18 is A and the pressure receiving area of the piston rod 19 is B, a force of Pd · A acts on the valve body 18 in the valve opening direction, and Pd · B acts on the piston rod 19 in the valve closing direction. Power works. Since the pressure receiving area A of the valve body 18 and the pressure receiving area B of the piston rod 19 are in a relationship of A> B, the valve body 18 and the piston rod 19 have a force of Pd (AB) in the valve opening direction. work. This difference (A−B) corresponds to the pressure receiving area of the conventional valve body, and conventionally, the size of the pressure receiving area directly restricts the flow rate of the refrigerant. However, in the present invention, although it has a large pressure receiving area of A and the refrigerant flow rate can be increased, the force acting in the valve opening direction with respect to the valve body 18 is as small as Pd (AB). Can be power.

Further, the end face of the piston rod 19 opposite to the valve body 18 receives the crank chamber pressure Pc through the passage 15 formed in the valve seat forming member 13, so that the valve opening direction Pc · B Force, Pc · A force acts in the valve closing direction of the valve body 18, and Pc · C in the valve opening direction and Ps in the valve closing direction, assuming that the pressure receiving area at the both ends of the shaft 23 is C.・ C's power will work. From this, the force acting in the valve closing direction by the solenoid force and the springs 20, 31, 32 is F, and the force in the valve opening direction balanced with this is:
F = Pd (A−B) + Pc (B + C−A) −Ps · C (1)
Can be expressed as

Here, since the difference (A−B) between the pressure receiving area A of the valve body 18 and the pressure receiving area B of the piston rod 19 is made equal to the pressure receiving area C of the shaft 23, substituting C into (AB). ,
F = C (Pd−Ps) (2)
Thus, the crank chamber pressure Pc is cancelled. Therefore, although the valve body 18 is large, the valve body 18 can constitute a valve having a substantially small pressure receiving area (AB).

  In the variable displacement compressor control valve 11 described above, when the control current is not supplied to the solenoid coil 33, the discharge pressure Pd pushes the valve body 18 having a larger pressure receiving area than the piston rod 19 in the valve opening direction. The valve body 18 is fully open. Therefore, in the variable capacity compressor, the pressure Pc in the crank chamber is close to the discharge pressure Pd, the pressure difference applied to both end faces of the compression piston is the smallest, and the oscillation plate has a stroke of the compression piston. The angle of inclination becomes the smallest, and the variable capacity compressor is operated at the minimum capacity.

  When the maximum control current is supplied to the solenoid coil 33, the movable iron core 30 is attracted to the fixed iron core 26, and the valve body 18 is pushed in the valve closing direction via the shafts 29, 23, thereby changing the variable capacity. The compressor control valve 11 is fully closed. As a result, in the variable capacity compressor, the refrigerant in the crank chamber flows to the suction chamber through the orifice, and the pressure Pc in the crank chamber decreases to a value close to the suction pressure Ps in the suction chamber and is applied to both end faces of the compression piston. The pressure difference becomes the largest, the swinging plate has an inclination angle that maximizes the stroke of the compression piston, and the variable capacity compressor shifts to the maximum capacity operation.

  In the case of normal control in which a predetermined control current is supplied to the solenoid coil 33, the movable iron core 30 is attracted by the fixed iron core 26 and moves in the valve closing direction according to the magnitude of the control current. Solenoid force is generated. Thereby, when the valve body 18 is closed, the valve body 18 is opened only when the differential pressure between the discharge pressure Pd and the suction pressure Ps becomes larger than a predetermined value set by the solenoid force. That is, during normal control, the variable displacement compressor control valve 11 operates as a differential pressure valve. Therefore, the control valve 11 for the variable capacity compressor senses the differential pressure between the discharge pressure Pd and the suction pressure Ps, and keeps the differential pressure at a predetermined differential pressure set by the solenoid. It will operate | move so that the flow volume of the refrigerant | coolant which flows into a crank chamber may be controlled.

It is a center longitudinal cross-sectional view which shows the control valve for variable capacity compressors of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Control valve for variable capacity compressor 12 Body 13 Valve seat forming member 14, 15, 16 Passage 17 Valve seat 18 Valve body 19 Piston rod 20 Spring 21 Strainer 22 Passage 23 Shaft 24 Body 25 Sleeve 26 Fixed iron core 27 Stopper 28 Guide 29 Shaft 30 Movable iron core 31, 32 Spring 33 Coil 34 Yoke

Claims (2)

The refrigerant discharge capacity from the variable capacity compressor is changed by controlling the flow rate of refrigerant introduced from the discharge chamber to the crank chamber so that the differential pressure between the suction pressure of the suction chamber and the discharge pressure of the discharge chamber is maintained at a predetermined value. In the 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;
It has a pressure receiving area smaller than that of the valve body, one end is fixed to the valve body through a valve hole and receives the discharge pressure, and the other end communicates the pressure led to the crank chamber with the crank chamber. A piston rod received through a passage communicating with the refrigerant passage on the side to be
The pressure receiving area equal to the difference between the pressure receiving area of the valve body and the pressure receiving area of the piston rod, one end receiving pressure introduced into the crank chamber by contacting the valve body, and the other end receiving the suction pressure A shaft to receive,
A solenoid that applies a solenoid force corresponding to the differential pressure of the predetermined value to the valve body via the shaft;
A control valve for a variable capacity compressor. 2. The control valve for a variable capacity compressor according to claim 1, wherein the piston rod extends in the same axial direction as the valve body and is formed integrally with the valve body.

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