JP2007303291A - Control valve for variable displacement compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure flow at a necessary flow rate necessary for surely dropping displacement when the delivery pressure Pd of a variable displacement compressor is low. <P>SOLUTION: A valve seat 13 which can move forward and rearward in an axial direction is arranged in a side receiving delivery pressure Pd and a valve element 17 is arranged in a downstream side thereof. The valve seat 13 moves the valve element 17 side by pressure difference between pressure Pc in a crank chamber and delivery pressure Pd when delivery pressure Pd is sufficiently high, and moves to a side separating from the valve element 17 by a spring 14 when pressure difference gets lower than established pressure difference. Consequently, since distance between the valve seat 13 and the valve element 17 during off operation of a solenoid is short in normal displacement control and gets longer when the delivery pressure is low to quickly increase section area of a passage through which refrigerant passes, the flow rate necessary for surely dropping displacement can be secured. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 for controlling a discharge capacity of a variable capacity compressor of an air conditioner system for an automobile.

  The compressor used in the refrigeration cycle of an automotive air conditioner system is a variable capacity compressor capable of varying the refrigerant discharge capacity so as to obtain an appropriate cooling capacity regardless of the rotational speed of the engine driving the compressor. Is used.

  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 pressure difference applied to both ends of the piston can be changed to change the inclination angle of the swinging plate, thereby changing the stroke of the piston and reducing the amount of refrigerant discharged. Can be changed. 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 controlling the flow rate of the refrigerant introduced into the crank chamber while the refrigerant leaks from the crank chamber to the suction chamber through the orifice. As the control valve for the variable capacity compressor, for example, a valve that is operated in accordance with a differential pressure between the discharge pressure Pd of the discharge chamber and the suction pressure Ps of the suction chamber (see, for example, Patent Document 1), to the crank chamber. There are known ones in which the flow rate of the refrigerant to be introduced is controlled to be turned on and off (see, for example, Patent Document 2).

  The control valve for a variable capacity compressor described in Patent Document 1 senses a differential pressure between the discharge pressure Pd of the discharge chamber and the suction pressure Ps of the suction chamber, and the differential pressure becomes a differential pressure set by a solenoid. In addition, the flow rate of the refrigerant at the discharge pressure Pd introduced from the discharge chamber into the crank chamber is controlled so that the discharge capacity of the refrigerant discharged from the variable capacity compressor is kept constant.

In the control valve for a variable capacity compressor described in Patent Document 2, capacity control is performed by supplying a current having a value corresponding to a set capacity to the coil of the solenoid. In order to improve the hysteresis of the valve characteristics, Capacitance control is performed by supplying a pulse current of about 400 Hz and changing its duty ratio. This control valve for a variable capacity compressor acts in a closing direction when the solenoid coil is energized to control the variable capacity compressor in a direction in which its capacity increases, and in a direction in which it opens when deenergized. It acts to control the variable capacity compressor in the direction of decreasing its capacity. Therefore, the control valve for the variable capacity compressor with duty ratio control has a set load set by an average current value to the solenoid corresponding to the duty ratio, and controls the capacity of the refrigerant discharged from the variable capacity compressor. Become.
JP 2001-132650 A JP 2004-293497 A

  In the variable capacity compressor, the refrigerant discharged from the discharge chamber is introduced into the crank chamber through the control valve for the variable capacity compressor, and the introduced refrigerant is leaked to the suction chamber through the orifice. The capacity of the variable capacity compressor control valve is varied by controlling the flow rate of the refrigerant introduced from the discharge chamber into the crank chamber. The variable capacity compressor has a high discharge pressure Pd when the load of the refrigeration cycle is large, and can introduce a sufficiently larger flow rate into the crank chamber than the flow rate that leaks into the suction chamber. It is high and a sufficient differential pressure (Pc−Ps) from the suction pressure Ps of the suction chamber is secured. For this reason, the variable capacity ratio can be freely varied between 0 to 100% by controlling the flow rate of the control valve for the variable capacity compressor. Conversely, when the load is reduced and the discharge pressure Pd is reduced, the flow rate that can be introduced into the crank chamber is reduced and the pressure Pc in the crank chamber is also relatively lowered. However, when it is desired to operate the variable capacity compressor at a minimum capacity with a variable capacity ratio of 0% in such a state, the flow rate introduced into the crank chamber is increased to increase the crank chamber pressure Pc. Therefore, the variable capacity compressor is controlled to the minimum capacity, but the pressure Pc of the crank chamber does not increase and the differential pressure (Pc-Ps) between the crank chamber and the suction chamber does not increase. There was a problem that it was not possible to shift to driving.

  The present invention has been made in view of the above points, and provides a control valve for a variable capacity compressor that can secure a necessary flow rate that can reliably reduce the capacity when the discharge pressure is low. For the purpose.

  In the present invention, in order to solve the above-mentioned problem, the first variable-pressure compressor control valve for varying the discharge capacity by controlling the flow rate of the refrigerant flowing from the discharge chamber of the variable-capacity compressor to the crank chamber is the first to introduce the refrigerant. And a solenoid for controlling the opening and closing of the valve portion, and the valve portion is generated when the refrigerant flows through the passage. There is provided a control valve for a variable capacity compressor having a flow rate variable mechanism that varies a maximum flow rate that can flow through the passage in accordance with a differential pressure across the front and rear.

  According to such a control valve for a variable capacity compressor, the flow rate variable mechanism allows the flow to flow through the valve portion when the differential pressure between the first port and the second port is small and when the differential pressure is large. The maximum flow rate that can be changed was changed. As a result, when the load on the refrigeration cycle decreases and the differential pressure decreases, the maximum flow rate that can flow to the valve portion can be increased. As a result, the flow rate of refrigerant flowing from the discharge chamber to the crank chamber increases rapidly. It becomes possible to reliably reduce the capacity of the variable capacity compressor.

  The control valve for a variable capacity compressor according to the present invention is provided with a flow rate variable mechanism in the valve portion so as to increase the maximum flow rate that can flow to the valve portion when the high pressure is reduced and no differential pressure is generated. Thus, a large amount of refrigerant can be sent to the crankcase at a time, and this can further reduce the capacity of the variable capacity compressor even when the high pressure is lowered, and the engine load that is the driving source can be reduced. There is an advantage that it can be further reduced.

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 capacity compressor according to the first embodiment, and FIG. 2 shows a main part of the control valve for the variable capacity compressor according to the first embodiment. It is an expanded sectional view.

  The control valve for a variable displacement compressor according to the first embodiment has a valve body 10 at the top of the figure. The body 10 is opened at the center of the upper portion thereof to receive a refrigerant having a discharge pressure Pd from the discharge chamber of the variable capacity compressor, and a refrigerant having a pressure Pc which is opened at the central side surface of the body 10 and is controlled to the crank chamber. And a port 12 for feeding into the port. The ports 11 and 12 communicate with each other through a passage formed in the axial direction inside the body 10. In a passage communicating with the port 11 into which the discharge pressure Pd is introduced, a valve seat 13 that is movable back and forth in the axial direction is disposed. The valve seat 13 has a valve hole formed so as to penetrate in the axial direction, is urged toward the port 11 by a spring 14, and movement in the direction of the port 11 is an opening of the port 11. It is regulated by a stopper 15 fixed to the end. Further, the cylindrical portion of the valve seat 13 is supported by the body 10 so as to be slidable in the axial direction, and the support portion is provided with a stepped portion 16 as can be seen well in FIG. Movement in a direction away from the port 11 is restricted. The valve seat 13 and the stepped portion 16 have a valve structure that closes the clearance between the body 10 and the valve seat 13 when the valve seat 13 is in contact with the stepped portion 16 against the biasing force of the spring 14. Yes.

  In the space communicating with the port 12, a valve element 17 that is movable back and forth in the axial direction is disposed so as to open and close the valve hole facing the valve seat 13. The valve body 17 is urged by a spring 18 in a direction away from the valve seat 13, that is, in a valve opening direction.

  A solenoid is disposed at the lower part of the body 10. This solenoid has a fixed iron core 19 fitted to the body 10 from below in the figure. The fixed iron core 19 has a space for accommodating the valve element 17 in the upper end surface thereof, and a bottom part of the space serves as a stopper that restricts the movement of the valve element 17 in the valve opening direction by the spring 18. When the valve element 17 is in contact with the bottom, the variable capacity compressor control valve is fully open. The fixed iron core 19 is fitted with a bottomed sleeve 20 at a lower portion thereof, and a movable iron core 21 is disposed in the bottomed sleeve 20 so as to be movable back and forth in the axial direction. It is urged away from 19.

  Further, a shaft 23 is loosely fitted to the solenoid so as to penetrate the fixed iron core 19 and the movable iron core 21 in the axial direction. The upper end of the shaft 23 in the figure is in contact with the bottom of a hole recessed in the valve body 17. A stopper 24 is fixed to the lower end portion of the shaft 23 in the figure, and a spring 25 is disposed between the stopper 24 and the bottom portion of the bottomed sleeve 20 to urge the shaft 23 toward the valve portion. is doing. The stopper 24 has an outer diameter larger than the inner diameter of the central hole of the movable iron core 21 into which the shaft 23 is loosely fitted. For this reason, when the movable iron core 21 is separated from the fixed iron core 19 by the urging force of the spring 22, the stopper 24 is brought into contact with the movable iron core 21 by the urging force of the spring 25, and the movable iron core 21 is fixed to the fixed iron core. When the shaft 19 is adsorbed, the tip (valve element) of the shaft 23 is seated on the valve seat 13 by the urging force of the spring 25, so that the stopper 24 is separated from the movable iron core 21. Yes.

  A coil 26 is disposed on the outer periphery of the bottomed sleeve 20, and a magnetic yoke 27 and a plate 28 are provided so as to wrap the coil 26, and a harness 29 for supplying power to the coil 26 attaches the plate 28. It penetrates to the outside. In the body 10, the O-ring 30 provided around the port 12 at a position above the port 12 has a high discharge pressure Pd when the variable displacement compressor control valve is mounted on the variable displacement compressor. The O-ring 31 provided around the fixed iron core 19 prevents leakage to the medium pressure port 12 side, and serves to seal between the medium pressure port 12 and the atmosphere.

  Here, in this control valve for a variable capacity compressor, first, the valve seat 13 provided on the side of the port 11 that receives the discharge pressure Pd is controlled to the discharge pressure Pd when the refrigerant flows through the valve portion. The differential pressure with respect to the pressure Pc is received, and as shown in FIG. When the refrigerant flowing through the valve portion is small and the differential pressure between the discharge pressure Pd and the controlled pressure Pc is small, the valve seat 13 is pushed back by the spring 14 and comes into contact with the stopper 15 as shown in FIG. That is, the valve seat 13 moves in the axial direction due to the differential pressure generated before and after the refrigerant flows through the valve hole, and acts as if the valve body 17 is relatively lifted.

  The control valve for the variable capacity compressor operates as an on / off valve that opens and closes the valve portion by supplying a pulse current to the solenoid. That is, the movable iron core 21 is separated from the fixed iron core 19 by the spring 22 having a stronger spring force than the spring 25 when the solenoid that is not energized to the coil 26 is off. At this time, the movable iron core 21 pushes the stopper 24 downward in the figure against the urging force of the spring 25, so that the shaft 23 is also pushed downward in the figure and follows this to follow the valve element 17 of the valve portion. Is separated from the valve seat 13 by the spring 18, and the control valve for the variable capacity compressor is opened.

  When the coil 26 is energized, the movable iron core 21 is attracted to the fixed iron core 19 against the urging force of the spring 22. As a result, the shaft 23 is pushed upward by the spring 25, the valve body 17 is seated on the valve seat 13, and the control valve for the variable capacity compressor is closed. At this time, the stroke that moves until the movable iron core 21 is attracted to the fixed iron core 19 is larger than the stroke that the shaft 23 moves until the valve element 17 is seated on the valve seat 13. When the compressor control valve is closed, the stopper 24 fixed to the shaft 23 is separated from the movable iron core 21.

  In other words, the control valve for the variable capacity compressor operates when an on / off pulse current is supplied to the coil 26. When the solenoid is off, the shaft 23 moves to a position where the spring 22 and the spring 25 are balanced. When the solenoid is on, the valve is closed by the urging force of the spring 25. 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 of the control valve for the variable capacity compressor and the variable capacity compressor equipped with the control valve will be described.
FIG. 3 is a diagram showing the relationship between the differential pressure between the crank chamber pressure and the suction pressure with respect to the variable capacity ratio of the variable displacement compressor, and FIG. 4 is a diagram showing the relationship between the current and the flow rate.

  3, the horizontal axis represents the variable capacity ratio of the variable capacity compressor, and the vertical axis represents the differential pressure (Pc−Ps) between the crank chamber pressure Pc and the suction pressure Ps. The numerical value in the figure is an example in the case of a refrigeration cycle using HFC-134a as a refrigerant.

  According to FIG. 3, the variable capacity compressor operates at a variable capacity ratio of 100% when there is no differential pressure between the crank chamber pressure Pc and the suction pressure Ps due to the control valve for the variable capacity compressor being closed. ing. When the control valve for the variable capacity compressor is opened, the crank chamber pressure Pc gradually increases, and the differential pressure (Pc-Ps) between the pressure Pc and the suction pressure Ps increases, the variable capacity ratio decreases accordingly. It has the characteristic of going on. When the load of the refrigeration cycle is high, for example, when the discharge pressure Pd is 1.5 MPa, when the differential pressure (Pc-Ps) rises to about 0.13 MPa, the variable capacity compressor has a variable capacity ratio of 0%, that is, the minimum You will drive with capacity. When the load is reduced and the discharge pressure Pd is reduced to 0.7 MPa, the differential pressure (Pc−Ps) at which the variable capacity ratio becomes 0% is about 0.1 MPa, and the discharge pressure Pd is reduced to 0.3 MPa. Then, the differential pressure (Pc−Ps) at which the variable capacity ratio becomes 0% can only rise to about 0.08 MPa.

  However, in practice, in order to reduce the variable capacity ratio of the variable capacity compressor to 0%, even if the discharge pressure Pd is reduced, the differential pressure (Pc−Ps) needs to be about 0.1 MPa. In order to ensure a differential pressure (Pc−Ps) of about 0.1 MPa even when the discharge pressure Pd decreases, when the discharge pressure Pd decreases, a large flow rate can flow from the discharge chamber to the crank chamber. You can do it. Therefore, in the control valve for a variable capacity compressor according to the present invention, when the load is high and the discharge pressure Pd is high, the valve seat position is determined by the differential pressure applied to the valve seat 13 before and after the valve seat 17 as shown in FIG. When the load is reduced and the discharge pressure Pd is lowered, the valve seat position is moved away from the valve body 17 as shown in FIG. 2, and the cross-sectional area of the passage through which the refrigerant passes is rapidly increased. I am doing so. The movement of the valve seat position is set so as to occur when the differential pressure before and after the valve seat 13, that is, the differential pressure (Pd−Pc) is reduced to, for example, about 0.1 MPa. This is done by adjusting the diameter of the cylindrical portion and the spring load of the spring 14.

  As described above, by increasing the valve size when the discharge pressure Pd decreases, the following effects can be obtained. That is, as shown in FIG. 4, in the conventional control valve for a variable capacity compressor, when the discharge pressure Pd is reduced, if the required flow rate that can be reliably reduced is f1, it can be adjusted by duty ratio control. The flow rate has a characteristic as indicated by a straight line A1. For this reason, if the practical flow rate range in which the capacity control is actually performed is a range of 0-f0, the range that can be adjusted by the duty ratio control is 58 to 100%. On the other hand, in the control valve for a variable displacement compressor of the present invention, the flow rate when the discharge pressure Pd is high and the valve seat position is moving toward the valve body 17 can be set to f which is smaller than f1. Like the curve A, since the inclination becomes small in the practical range, the range that can be controlled by the duty ratio control can be expanded to 30 to 100%. In addition, the flow rate when the discharge pressure Pd decreases and the valve seat position moves to the side away from the valve body 17 secures f1.

  FIG. 5 is a central longitudinal sectional view showing the structure of the control valve for a variable capacity compressor according to the second embodiment when the differential pressure is larger than the set differential pressure, and FIG. 6 is related to the second embodiment. It is an expanded sectional view which shows the principal part of the control valve for variable capacity compressors in a state when the differential pressure is smaller than the set differential pressure. 5 and 6, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The variable displacement compressor control valve according to the second embodiment is an on / off operation control valve as compared with the variable displacement compressor control valve according to the first embodiment. This is the same in that the valve lift in the valve portion is increased when Pd is lowered, but the point is that the position of the fixed iron core 19 of the solenoid is moved together with the valve seat 13 at that time.

  That is, in the control valve for a variable capacity compressor according to the second embodiment, the valve seat 13 and the fixed iron core 19 are fixed, the discharge pressure Pd is high, and the valve seat 13 is caused by the differential pressure before and after. The position shown in FIG. 5 where the valve seat 13 abuts against the stepped portion 16 by moving downstream, and the valve seat 13 and the fixed iron core 19 abut against the stopper 15 by the biasing force of the spring 14 because the discharge pressure Pd is low. The valve seat 13 and the fixed iron core 19 are configured to move between the positions shown in FIG.

  As a result, when the discharge pressure Pd is high and the control valve for the variable capacity compressor performs normal capacity control, the fixed iron core 19 moves to the movable iron core 21 side, and the fixed iron core 19 and the movable iron core are moved. When the minimum gap is controlled by reducing the magnetic gap with respect to 21 and turning off the solenoid, the magnetic gap becomes large. Therefore, the fixed iron core 19 and the movable iron core when performing normal capacity control are used. The suction force between the two can be increased.

  In this variable capacity compressor control valve, the fixed iron core 19 is axially disposed in a space formed by the connecting member 33 fitted to the body 10 from below in the figure and the bottomed sleeve 20 fixed thereto. The valve body 17 of the valve portion is configured integrally with a solenoid shaft 23. Further, it is a spring 18 disposed between the fixed iron core 19 and the movable iron core 21 that urges the valve body 17 in the valve opening direction, and functions as a stopper for determining the fully open position of the valve portion. This is the bottom of the bottomed sleeve 20 that restricts the downward movement of the movable iron core 21 in the figure.

  The variable displacement compressor control valves according to the first and second embodiments described above are described in the case where the flow rate of the refrigerant supplied from the discharge chamber to the crank chamber is controlled by duty ratio control of the pulse current that supplies power to the solenoid. However, when the differential pressure across the valve is smaller than the set differential pressure, the flow rate variable mechanism that can vary the maximum flow rate that can be increased by rapidly increasing the valve lift is applied to control valves of other control systems. be able to. Next, an example in which the flow rate variable mechanism is applied to a control valve for a variable capacity compressor that is configured to control the differential pressure between the discharge pressure Pd and the suction pressure Ps to be constant will be described.

  FIG. 7 is a central longitudinal sectional view showing the structure of the control valve for a variable capacity compressor according to the third embodiment when the differential pressure is larger than the set differential pressure, and FIG. 8 is related to the third embodiment. It is an expanded sectional view which shows the principal part of the control valve for variable capacity compressors in a state when the differential pressure is smaller than the set differential pressure. 7 and 8, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The control valve for a variable capacity compressor according to the third embodiment includes a port 35 that receives the suction pressure Ps of the suction chamber in the body 10, and the valve body 17 has a discharge pressure Pd and a suction pressure at both ends in the axial direction thereof. It receives Ps and is always urged by the spring 18 so as to come into contact with the shaft 23 of the solenoid so that the position of the valve body 17 can be controlled by the solenoid.

  As a result, when the capacity control is performed within the range in which the control valve for the variable capacity compressor can control the capacity, the discharge pressure Pd is high and the flow rate of the refrigerant flowing through the valve hole is large. The valve seat 13 is moved downstream by the differential pressure before and after the valve seat 13 and is in contact with the step portion 16, and the valve portion is set in a state where the valve lift is relatively small.

  In this state, when a predetermined control current corresponding to the load is supplied to the solenoid, the valve body 17 is moved in the axial direction to a position corresponding to the control current. At this time, since the valve element 17 receives the discharge pressure Pd in the valve opening direction and the suction pressure Ps in the valve closing direction, the valve portion is opened and closed by the differential pressure (Pd−Ps). Therefore, the control valve for the variable capacity compressor senses the pressure difference (Pd−Ps) between the discharge pressure Pd and the suction pressure Ps and discharges the discharge chamber so that the pressure difference becomes the pressure difference set by the solenoid. The flow rate of the refrigerant flowing from the engine to the crank chamber is controlled.

  On the other hand, when the load of the refrigeration cycle is reduced and the discharge pressure Pd is decreased and the differential pressure across the valve seat 13 becomes lower than the set differential pressure, the valve seat 13 is moved to a spring as shown in FIG. 14 is moved until it abuts against the stopper 15, and the valve portion is set to a relatively large valve lift. As a result, even if the discharge pressure Pd is low, the control valve for the variable capacity compressor opens further than the fully open state during normal control, so that a large amount of refrigerant can flow to the crank chamber at one time. It will be possible to reliably reduce the capacity.

  The variable displacement compressor control valve according to the first to third embodiments described above greatly changes the valve lift when the differential pressure between the discharge pressure Pd and the crank chamber pressure Pc becomes smaller than the set differential pressure. The flow rate variable mechanism that greatly changes the maximum flow rate that the control valve can flow has been described. Next, the valve lift does not change, and the maximum flow rate that can be flowed by the control valve is greatly changed by greatly changing the valve diameter. The flow rate variable mechanism will be described.

  FIG. 9 is a central longitudinal sectional view showing the structure of the control valve for a variable capacity compressor according to the fourth embodiment when the differential pressure is larger than the set differential pressure, and FIG. 10 is related to the fourth embodiment. It is an expanded sectional view showing the important section of a control valve for variable capacity compressor, (A) shows a fully closed state, and (B) shows a state when a differential pressure is smaller than a set differential pressure. In FIG. 9 and FIG. 10, components having the same or equivalent functions as those shown in FIG. 1 and FIG.

  The variable displacement compressor control valve according to the fourth embodiment is a duty ratio control valve for on / off operation, and has a port 11 for receiving the discharge pressure Pd on the side surface of the body 10 to the crank chamber. A port 12 for supplying the controlled pressure Pc is provided at the tip of the body 10. This port 12 has a large opening so that a large flow rate can flow when the discharge pressure Pd becomes low, and this constitutes a valve hole that opens when the discharge pressure Pd becomes low. Yes. A valve element 37 that opens and closes the valve hole is disposed on the upstream side of the valve hole so as to advance and retreat in the axial direction, and is urged by the spring 14 in the valve opening direction. When the discharge pressure Pd is low, the upper end surface of the fixed iron core 19 in the figure is the stepped portion 16, and the valve body 37 is in contact with the stepped portion 16. The port 12, the valve body 37, and the spring 14 forming the valve hole constitute a flow rate variable mechanism.

  The valve body 37 of the flow rate variable mechanism has a hole formed through in the axial direction thereof, and this constitutes a valve hole of the valve portion. A valve element 17 for opening and closing the valve hole is held at the tip of a shaft 23 of the solenoid.

  Here, when the capacity control is performed in a range where the capacity control of the variable capacity compressor control valve is possible, the discharge pressure Pd is high, and the flow rate of the refrigerant flowing through the valve hole formed in the valve body 37 is large. As shown in FIG. 9, the valve element 37 is closed by the differential pressure between the discharge pressure Pd and the crank chamber pressure Pc, and the valve diameter of the valve portion is the inner diameter of the valve hole formed in the valve element 37. Will be set by. When the variable displacement compressor control valve performs duty ratio control and the solenoid is not energized, the valve element 17 is in the position shown in FIG. 9 and the solenoid is energized. At this time, as shown in FIG. 10A, the valve hole formed in the valve element 37 is in a closed position, and reciprocates between the two positions.

  On the other hand, when the discharge pressure Pd decreases due to a reduction in the load of the refrigeration cycle, and the differential pressure across the valve portion becomes lower than the set differential pressure, the valve body 37 is spring-loaded as shown in FIG. 14, the valve diameter of the valve portion is switched from the small inner diameter of the valve hole formed in the valve body 37 to the larger inner diameter of the port 12. As a result, even if the discharge pressure Pd is low, the control valve for the variable capacity compressor opens further than the fully open state during normal control, so that a large amount of refrigerant can flow to the crank chamber at one time. It will be possible to reliably reduce the capacity.

  In the above embodiment, the case where the present invention is applied to the control valve for controlling the variable capacity compressor of the refrigeration cycle using HFC-134a as the refrigerant has been described. However, the refrigeration cycle using other refrigerant such as carbon dioxide is variable. The same can be applied to a control valve used in a capacity compressor.

It is a center longitudinal cross-sectional view which shows the structure of the control valve for variable capacity compressors which concerns on 1st Embodiment. It is an expanded sectional view showing an important section of a control valve for variable capacity compressors concerning a 1st embodiment. It is a figure which shows the relationship of the pressure difference of the crank chamber pressure and suction pressure with respect to the variable capacity ratio of a variable capacity compressor. It is a figure which shows the relationship of the flow volume with respect to an electric current. It is a center longitudinal cross-sectional view which shows the structure of the control valve for variable displacement compressors concerning 2nd Embodiment in a state when a differential pressure is larger than a setting differential pressure. It is an expanded sectional view which shows the principal part of the control valve for variable displacement compressors concerning 2nd Embodiment in a state when a differential pressure is smaller than a setting differential pressure. It is a center longitudinal cross-sectional view which shows the structure of the control valve for variable displacement compressors concerning 3rd Embodiment in the state when a differential pressure is larger than a setting differential pressure. It is an expanded sectional view which shows the principal part of the control valve for variable displacement compressors concerning 3rd Embodiment in the state when a differential pressure is smaller than a setting differential pressure. It is a center longitudinal cross-sectional view which shows the structure of the control valve for variable capacity compressors which concerns on 4th Embodiment in a state when a differential pressure is larger than a setting differential pressure. It is an expanded sectional view which shows the principal part of the control valve for variable displacement compressors concerning 4th Embodiment, (A) shows a fully closed state, (B) is when differential pressure is smaller than setting differential pressure Shows the state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Body 11, 12 Port 13 Valve seat 14 Spring 15 Stopper 16 Step part 17 Valve body 18 Spring 19 Fixed iron core 20 Bottomed sleeve 21 Movable iron core 22 Spring 23 Shaft 24 Stopper 25 Spring 26 Coil 27 Yoke 28 Plate 29 Harness 30 , 31 O-ring 33 Connecting member 35 Port 37 Valve body

Claims (9)

In a control valve for a variable capacity compressor that controls the flow rate of refrigerant flowing from the discharge chamber of the variable capacity compressor to the crank chamber to vary the discharge capacity,
A valve portion for opening and closing a passage between the first port for introducing the refrigerant and the second port for deriving the refrigerant, and a solenoid for controlling opening and closing of the valve portion,
The variable valve compressor has a flow rate variable mechanism that varies a maximum flow rate that can flow through the passage according to a differential pressure before and after the refrigerant flows through the passage. Control valve.   2. The control for a variable capacity compressor according to claim 1, wherein the variable flow rate mechanism is configured to change the maximum flow rate by changing a position of a valve seat of the valve portion according to the differential pressure. valve.   The variable flow rate mechanism is configured such that the valve seat is disposed so as to be movable back and forth in the axial direction of the passage and is biased in a direction away from a valve body disposed on the downstream side of the valve seat by a spring. 3. The control valve for a variable capacity compressor according to claim 2, wherein the valve lift is increased when the pressure is smaller than the set differential pressure.   The control valve for a variable capacity compressor according to claim 3, wherein the valve body opens and closes a valve hole of the valve seat by the solenoid of duty ratio control.   The solenoid has a fixed iron core that is disposed so as to be capable of moving back and forth in the axial direction, is fixed to the valve seat, and changes its position in the axial direction together with the valve seat according to the differential pressure. The control valve for a variable capacity compressor according to claim 4.   The valve body has an end opposite to the valve seat side extending to a third port communicating with the suction chamber of the variable capacity compressor, and a discharge pressure introduced into the first port and the 4. The control valve for a variable capacity compressor according to claim 3, wherein the passage is controlled to open and close by a pressure difference from a suction pressure introduced into the third port.   2. The control valve for a variable capacity compressor according to claim 1, wherein the flow rate variable mechanism changes a valve diameter of the valve portion according to the differential pressure.   The flow rate variable mechanism includes a valve body that opens and retreats in the axial direction of the passage on the upstream side of the second port as a valve hole and opens and closes the second port; and a valve opening direction of the valve body And a valve hole having a smaller diameter than the second port is formed in the axial direction so as to close the second port by the differential pressure. 8. The control valve for a variable capacity compressor according to claim 7, wherein the control valve functions as a valve seat of the valve portion. 9. The control valve for a variable capacity compressor according to claim 8, wherein the valve portion opens and closes the valve hole having a small diameter formed in the valve body by the solenoid of duty ratio control.

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