JP2006194175A - Control valve for variable displacement compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control valve for a variable displacement compressor capable of coping with occurrence of abnormally high pressure and being controlled by turning on and off. <P>SOLUTION: This control valve is opened by moving a stopper 19 in the direction in which it leaves a fixed iron core 14 by a movable iron core 16 by a spring 17 and letting a shaft 18 fixed to the stopper 19 leave a valve seat 13 when a solenoid is off and is closed by attracting the movable iron core 16 on the fixed iron core 14 by stroke larger than the shaft 18 and seating the shaft 18 on the valve seat 13 by a spring 20 when the solenoid is on. When discharge pressure Pd becomes abnormally high pressure, the shaft 18 is pushed and opened by bending the spring 20 due to difference between the discharge pressure Pd and pressure Pc in a crank chamber for relief into the crank chamber so that pressure Pc in the crank chamber rises and the variable displacement compressor is shifted to the minimum discharge capacity operation side to reduce abnormally high pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control valve for a variable capacity compressor, and more particularly to an on / off control type control valve for a variable capacity compressor that controls the discharge capacity of the variable capacity compressor of an automotive air conditioner system.

  A compressor used in a refrigeration cycle of an automotive air conditioner system cannot perform rotation speed control because it uses an engine whose rotation speed varies depending on the running state as a drive source. Therefore, in general, a variable capacity compressor capable of varying the refrigerant discharge capacity is used in order to obtain an appropriate cooling capacity without being restricted by the engine speed.

  In a variable capacity compressor, generally, an oscillating plate provided with a variable inclination angle is driven by a rotary motion of a rotating shaft in an airtight crank chamber, and the oscillating motion of the oscillating plate is performed. Thus, the piston reciprocating in the direction parallel to the rotation axis sucks the refrigerant in the suction chamber into the cylinder and compresses it, and then discharges it into the discharge chamber. At this time, by changing the pressure in the crank chamber, the tilt angle of the swing plate can be changed by the pressure difference applied to both ends of the piston, thereby changing the stroke of the piston and changing the refrigerant discharge amount. Be made. The control valve for the variable capacity compressor controls the pressure in the crank chamber to change.

  Such a variable capacity compressor control valve for variably controlling the discharge capacity of the variable capacity compressor is generally provided in a crank chamber in which a part of the refrigerant having the discharge pressure Pd discharged from the discharge chamber is hermetically formed. The pressure Pc in the crank chamber is controlled by introducing the pressure and controlling the introduction amount. There is known a variable capacity compressor control valve that controls the amount of refrigerant introduced into the crank chamber in accordance with, for example, the pressure difference between the discharge pressure Pd of the discharge chamber and the suction pressure Ps of the suction chamber (for example, , See Patent Document 1).

According to this variable capacity compressor control valve, the differential pressure between the discharge pressure Pd of the discharge chamber and the suction pressure Ps of the suction chamber is sensed, and the differential pressure is set from the discharge chamber so as to become the differential pressure set by the solenoid. By controlling the flow rate of the refrigerant having the discharge pressure Pd introduced into the crank chamber, the discharge capacity of the refrigerant discharged from the variable capacity compressor is kept constant.
JP 2001-132650 A (paragraphs [0043] to [0045], FIG. 4)

  However, such a variable capacity compressor control valve has a problem that it is expensive due to its complicated structure. Further, in a refrigeration cycle using carbon dioxide having a very high operating pressure as a refrigerant, for example, a control circuit for controlling a variable capacity compressor control valve, a pressure sensor for detecting refrigerant pressure, or the like fails, and the variable capacity compressor control valve Has a problem that the variable capacity compressor or the like may be destroyed when the high pressure portion in the refrigeration cycle becomes abnormally high pressure.

  The present invention has been made in view of the above points, and provides a variable displacement compressor control valve that has a simple structure and can prevent destruction of the variable displacement compressor even if an abnormally high pressure occurs. With the goal.

  In the present invention, in order to solve the above problems, in a control valve for a variable capacity compressor, the flow rate of the refrigerant flowing from the discharge chamber of the variable capacity compressor to the crank chamber is controlled on and off to vary the discharge capacity. A valve body that is arranged downstream of the valve hole into which the refrigerant discharged from the discharge chamber is introduced, opens and closes the valve hole, and opens the valve part when not energized, and A solenoid that closes the valve, and the solenoid receives a discharge pressure of the refrigerant introduced from the discharge chamber in the valve opening direction, and the valve body biases the valve spring in the valve opening direction when not energized. And a second spring urged in the valve closing direction, and is held in the valve closing position by the second spring when energized, for a variable capacity compressor A control valve is provided.

  According to such a control valve for a variable capacity compressor, the second spring is closed against the discharge pressure that the valve body receives in the valve opening direction when energized. Thereby, when the discharge pressure becomes an abnormally high pressure, the urging force of the second spring is overcome and the valve is opened. Therefore, if the high pressure section in the refrigeration cycle becomes abnormally high due to malfunction, the variable capacity compressor control valve can be opened automatically and the abnormal high pressure can be relieved to the crank chamber. The capacity compressor is moved to the minimum discharge capacity operation side, the discharge pressure is lowered, and it is possible to prevent the breakage due to the abnormally high pressure.

  The control valve for a variable capacity compressor according to the present invention opens when the discharge pressure becomes abnormally high due to the differential pressure between the discharge pressure and the pressure to the crank chamber. Relief, and the variable capacity compressor is controlled to the minimum discharge capacity operation side, so that the abnormal high pressure is reduced, and at least the variable capacity compressor can be prevented from being destroyed. is there.

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 configuration of a control valve for a variable displacement compressor, and FIG. 2 is a central longitudinal sectional view showing an operation state of the control valve for a variable displacement compressor when the solenoid is on.

  This control valve for a variable displacement compressor has a valve body 10 at the top of the figure. The body 10 has a port 11 for receiving the discharge pressure Pd at the upper center thereof and a port 12 for deriving the pressure Pc controlled in the crank chamber. The port 11 and the port 12 communicate with each other inside the body 10, and an extended portion of the port 11 forms a valve hole, and a portion of the valve hole opened in an internal space communicating with the port 12 is a valve seat 13. I am doing.

  A solenoid is disposed at the lower part of the body 10. This solenoid has a fixed iron core 14 fitted to the body 10 from below in the figure. The fixed iron core 14 is fitted with a bottomed sleeve 15 at a lower portion thereof. The bottomed sleeve 15 is welded to the fixed iron core 14 and the inside thereof is kept airtight. Inside the bottomed sleeve 15, a movable iron core 16 is disposed so as to be movable back and forth in the axial direction, and is urged by a spring 17 in a direction away from the fixed iron core 14.

  Further, a shaft 18 is loosely fitted into the solenoid so as to penetrate the fixed iron core 14 and the movable iron core 16 in the axial direction. The upper end of the shaft 18 in the drawing constitutes a valve body of a valve portion that can be brought into contact with and separated from the valve seat 13 of the valve portion. A stopper 19 is fixed to the lower end of the shaft 18 in the figure, and a spring 20 is disposed between the stopper 19 and the bottom of the bottomed sleeve 15, and the shaft 18 is attached in the direction of the valve seat 13. It is fast. The stopper 19 has an outer diameter larger than the inner diameter of the central hole of the movable iron core 16 into which the shaft 18 is loosely fitted. For this reason, when the movable iron core 16 is separated from the fixed iron core 14 by the urging force of the spring 17, the stopper 19 is brought into contact with the movable iron core 16 by the urging force of the spring 20, and the movable iron core 16 is fixed to the fixed iron core. When attracted to the core 14, the tip (valve element) of the shaft 18 is seated on the valve seat 13 by the urging force of the spring 20, so that the stopper 19 is separated from the movable iron core 16.

  A coil 21 is disposed on the outer periphery of the bottomed sleeve 15. A magnetic material yoke 22 and a plate 23 are provided so as to wrap the coil 21, and a harness 24 for supplying power to the coil 21 attaches the plate 23. It penetrates to the outside. In the body 10, the O-ring 25 provided at a position above the port 12 in the figure has a high discharge pressure Pd when the variable displacement compressor control valve is mounted on the variable displacement compressor. The O-ring 26 provided around the fixed iron core 14 prevents leakage to the medium pressure port 12 side, and serves to seal between the medium pressure port 12 and the atmosphere.

  The variable displacement compressor control valve configured as described above operates as an on / off valve that opens and closes the valve portion by supplying a pulse current to the solenoid. That is, when the solenoid that is not energized to the coil 21 is off, the movable iron core 16 is separated from the fixed iron core 14 by the spring 17 having a spring force stronger than that of the spring 20 as shown in FIG. At this time, the movable iron core 16 pushes the stopper 19 downward against the urging force of the spring 20, so that the tip (valve body) of the shaft 18 is separated from the valve seat 13, and this variable capacity compressor is used. The control valve is opened.

  When the solenoid energized to the coil 21 is turned on, the movable iron core 16 is attracted to the fixed iron core 14 against the urging force of the spring 17 as shown in FIG. As a result, the shaft 18 is pushed upward by the spring 20, the valve body at the tip is seated on the valve seat 13, and the control valve for the variable capacity compressor is closed. At this time, since the stroke that moves until the movable iron core 16 is attracted to the fixed iron core 14 is larger than the stroke that moves until the tip of the shaft 18 is seated on the valve seat 13, the variable capacity compressor When the control valve is closed, the stopper 19 fixed to the shaft 18 is separated from the movable iron core 16.

  As described above, the control valve for the variable capacity compressor operates when the on / off pulse current is supplied to the coil 21, and when the solenoid is off, the shaft is in a position where the spring 17 and the spring 20 are balanced. 18 is moved to open the valve, and when the solenoid is on, the valve is closed by the urging force of the spring 20. The flow rate of the refrigerant supplied to the crank chamber is controlled by changing the duty ratio of the pulse current.

Next, the operation in the case where the variable displacement compressor control valve operates abnormally due to a failure of the control device on the control side thereof, a sensor connected to the control device, and the like will be described.
In the case of a failure in which the solenoid-off state persists, the control valve for the variable displacement compressor is maintained in the open state. At this time, the variable displacement compressor is in the minimum discharge capacity operation, so the refrigeration cycle The inside does not become abnormally high pressure.

  Conversely, in the case of a failure that keeps the solenoid-on state, the variable displacement compressor control valve is maintained in the closed state. As a result, the variable capacity compressor continues to operate at the maximum discharge capacity operation, so that the high pressure section in the refrigeration cycle becomes abnormally high pressure. At this time, the control valve for the variable capacity compressor receives a high discharge pressure Pd at the port 11, and the port 12 is at a medium pressure Pc. Since the port 12 communicates with the bottomed sleeve 15 in which the movable core 16 is accommodated via a clearance between the fixed core 14 and the shaft 18, the pressure in the bottomed sleeve 15 is communicated. Is the pressure Pc. That is, the shaft 18 receives the discharge pressure Pd in the valve opening direction at the tip constituting the valve body, and receives the load of the spring 20 and the pressure Pc in the valve closing direction.

  In this state, as a result of the variable capacity compressor continuing the maximum discharge capacity operation, the discharge pressure Pd is increased, and the differential pressure between the discharge pressure Pd and the crank chamber pressure Pc exceeds a predetermined pressure (for example, 10 MPa). When such an abnormally high pressure is reached, the force that pushes the shaft 18 in the valve opening direction becomes superior. Therefore, the shaft 18 deflects the spring 20 and moves in the valve opening direction. This control valve for the variable capacity compressor is The valve opens.

  That is, when the discharge pressure Pd of the variable capacity compressor becomes an abnormally high pressure, the control valve for the variable capacity compressor detects that the shaft 18 opens and relieves the high pressure to the crank chamber. Thereby, since the variable capacity compressor is moved to the discharge capacity minimum operation side, the discharge pressure Pd is lowered, and the breakage due to the abnormally high pressure can be prevented.

  In the above embodiment, the shaft 18 is shown as being loosely fitted through the fixed iron core 14 and the movable iron core 16 in the axial direction, but preferably the shaft 18 is connected to the port 11 and the fixed iron. A bearing for positioning on the same axis as the axis of the core 14 may be provided in the vicinity of both end positions.

It is a center longitudinal cross-sectional view which shows the structure of the control valve for variable capacity compressors. It is a center longitudinal cross-sectional view which shows the operation state of the control valve for variable capacity compressors at the time of solenoid-on.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Body 11, 12 Port 13 Valve seat 14 Fixed iron core 15 Bottomed sleeve 16 Movable iron core 17 Spring 18 Shaft 19 Stopper 20 Spring 21 Coil 22 Yoke 23 Plate 24 Harness 25, 26 O-ring

Claims (3)

In the control valve for a variable capacity compressor, the flow rate of the refrigerant flowing from the discharge chamber of the variable capacity compressor to the crank chamber is controlled on and off to vary the discharge capacity.
A valve body having a valve body disposed downstream of a valve hole into which the refrigerant discharged from the discharge chamber is introduced, opens and closes the valve hole, opens the valve section when not energized, and opens the valve section when energized And a solenoid for closing the valve,
The solenoid receives a discharge pressure of a refrigerant introduced from the discharge chamber in the valve opening direction, and a second spring that biases the valve body in a valve closing direction and a first spring that biases the valve body in a valve opening direction when not energized. A variable displacement compressor control valve, wherein the control valve is held in a valve-opening position by a spring, and is held in a valve-closing position by the second spring when energized.   The solenoid moves a stroke in which the movable iron core moves from the valve opening position of the valve body to the fixed iron core when energized, and the valve body moves from the valve opening position to the valve closing position when energized. 2. The control valve for a variable capacity compressor according to claim 1, wherein the control valve is set to be larger than the stroke. In the solenoid, the fixed iron core, the first spring, the movable iron core, the stopper, and the second spring are arranged in this order on the same axis as the valve hole from the valve portion side, and the fixed It has a shaft that is loosely fitted through the iron core and the movable iron core in the axial direction, one end constitutes the valve body that opens and closes the valve hole, and the other end is fixed to the stopper. The control valve for a variable capacity compressor according to claim 2.

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