JP2004156575A - Capacity control valve for variable displacement compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacity control valve of duty-ratio control for a variable displacement compressor, which is improved in characteristics near a valve closed position. <P>SOLUTION: A valve portion 10 includes a spool valve body 16, a coil spring 15 energizing the spool valve body 16 to a valve hole in the insertion direction, and a shaft 17 controlling an amount of lift of the spool valve body 16 against the spring force, and a flow rate of a cooling medium with a discharge pressure Pd is controlled to determine a pressure Pc in a crank chamber. A solenoid portion 20 drives the spool valve body 16 through a diaphragm 19 subjected to a suction pressure Ps in a suction chamber to set opening of the valve portion 10. In this way, the spool valve body 16 finely vibrated by the duty-ratio control does not collide with a valve seat 11b near the valve closed position, so that a lift characteristic is improved and durability of component parts is improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a displacement control valve for a variable displacement compressor used in a refrigeration cycle of an automotive air conditioner, and more particularly, to a displacement control valve for a variable displacement compressor that controls a duty ratio of an electromagnetic solenoid for setting a valve opening. .
[0002]
[Prior art]
In a variable displacement compressor used in a refrigeration cycle of an automotive air conditioner, a displacement control valve opens and closes a communication passage that connects a discharge chamber and a crank chamber, and a high pressure refrigerant is introduced from the discharge chamber into the crank chamber. By controlling the pressure, the inclination angle of the swash plate is controlled to control the discharge capacity of the refrigerant compressed by the piston.
[0003]
The capacity control valve performs capacity control by supplying a current corresponding to the set capacity to the electromagnetic coil of the electromagnetic solenoid, but supplies a pulse current of about 400 Hz and changes the duty ratio to control the capacity. In some cases. In the capacity control valve of the duty ratio control, a set load is set by an average current value to the electromagnetic solenoid according to the duty ratio, and the discharge capacity of the refrigerant from the variable capacity compressor can be controlled (for example, Patent Document 1). reference.).
[0004]
In such a displacement control valve, a ball valve having a ball-shaped valve element, a needle valve or taper valve having a tapered shape, a flat valve having a planar shape, and the like are employed. The control of the flow rate of the refrigerant from the discharge chamber to the crank chamber is performed by changing the lift amount of the valve body.When the variable capacity compressor operates at the minimum capacity, the lift amount is maximum, and when the variable capacity compressor is operating at the maximum capacity, The lift amount is minimized, that is, the valve is closed.
[0005]
[Patent Document 1]
JP 2001-342946 A (paragraph number [0019])
[0006]
[Problems to be solved by the invention]
However, in the capacity control valve of the duty ratio control, the valve body and the shaft for driving the valve body vibrate slightly in the longitudinal direction, so that the suction pressure is reduced during the valve closing operation or when the valve body is near the valve closing position. If the valve body is raised and controlled in the valve closing direction, the valve body hits the valve seat and the valve body moves in the valve opening direction, so that there is a problem that the lift characteristics are not linear.
[0007]
In addition, when the valve is closed, the slightly vibrating valve body collides directly and repeatedly with the valve seat, so that the durability of the valve body and the valve seat is reduced.
The present invention has been made in view of such a point, and an object of the present invention is to provide a displacement control valve for duty ratio control for a variable displacement compressor having improved characteristics near a valve closing position.
[0008]
[Means for Solving the Problems]
In the present invention, in order to solve the above-mentioned problem, in a displacement control valve of a variable displacement compressor that performs setting of a valve opening degree by controlling a duty ratio of a pulse current supplied to an electromagnetic solenoid, a first port through which a refrigerant is introduced is provided. There is provided a displacement control valve for a variable displacement compressor, wherein a valve for controlling the opening and closing of a passage between the refrigerant and a second port is constituted by a spool valve.
[0009]
According to the displacement control valve of such a variable displacement compressor, the valve portion is constituted by the spool valve, and the valve element of the spool valve is duty-ratio controlled by the electromagnetic solenoid, thereby causing minute vibration in the opening and closing direction of the valve. Even when the valve is closed, there is no collision of the valve body with the valve seat due to vibration near the valve closing position, so there is no valve opening phenomenon due to collision with the valve seat immediately before the valve is closed, and only the lift characteristics are improved. And the durability of the parts is improved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating the displacement control valve according to the first embodiment.
[0011]
The control valve includes a valve section 10 and a solenoid section 20, and constitutes an external variable control type control valve. This control valve is interposed in a communication passage communicating with the discharge chamber, the suction chamber, and the crank chamber when incorporated in a variable displacement compressor (not shown).
[0012]
The valve portion 10 has a pressure introduction chamber 12 formed at one longitudinal end of a body 11, and a first port 11 a above the pressure introduction chamber 12, which is in communication with a discharge chamber of a variable displacement compressor and receives a discharge pressure Pd. Is formed. A filter 13 is mounted in a space communicating with the first port 11a. The pressure introducing chamber 12 is provided with an adjusting screw 14, a coil spring 15, and a spool valve body 16.
[0013]
The spool valve body 16 is disposed so as to be able to be inserted into and removed from the valve hole from the upstream side facing the valve seat 11b, and a tapered portion 16a and a spring receiving portion are integrally formed on the upper portion. Being energized. The upper end of the coil spring 15 is received by the adjusting screw 14, and the spring load is adjusted by the amount of screwing.
[0014]
A second port 11c communicating with the crank chamber is formed on a side surface of the body 11 downstream of the valve hole of the valve portion 10. Therefore, the refrigerant introduced from the first port 11a is guided to the crank chamber through the opening controlled by the spool valve element 16 and the valve seat 11b, thereby controlling the angle of the swash plate in the crank chamber. Pressure Pc in the crank chamber is determined.
[0015]
The spool valve element 16 is integrally formed with a shaft 17 extending downward through a valve hole, and is held by the body 11 so as to be slidable in the axial direction together with the spool valve element 16.
[0016]
The lower end of the shaft 17 is fitted into the center disk 18. The center disk 18 is provided so that the outer peripheral edge thereof comes into contact with the center of the diaphragm 19 sandwiched between the body 11 and the solenoid portion 20. The space in which the center disk 18 is disposed communicates with the third port 11d, and the diaphragm 19 receives the suction pressure Ps from the suction chamber of the variable displacement compressor.
[0017]
The diaphragm 19 receives the introduced suction pressure Ps, and can be displaced in the vertical direction in the drawing to control the lift amount of the spool valve element 16 via the center disk 18 and the shaft 17.
[0018]
The solenoid section 20 has a sleeve 22 around which an electromagnetic coil 21 is provided, and a lower end thereof is fixed with a core 23 forming a fixed iron core. A plunger 24 forming a movable iron core is slidably disposed within the sleeve 22 in a state where the plunger 24 is urged upward in the axial direction by a coil spring 25. The shaft 26 is arranged at the axial position of the core 23 and the plunger 24, and one end thereof is supported by a bearing 27 press-fitted into an opening of the core 23, and the other end is connected to the plunger 24. Thereby, when the electromagnetic coil 21 is energized and the plunger 24 is attracted to the core 23, the spool valve body 16 is inserted into the valve hole by the coil spring 15, and the valve is closed. However, when the electromagnetic coil 21 is in a non-energized state, the urging force of the coil spring 25 acts on the plunger 24, and the shaft 17 is pushed upward from the diaphragm 19 through the center disk 18 so that the spool valve is moved upward. The body 16 is lifted by a predetermined distance in the valve opening direction.
[0019]
As described above, in this displacement control valve, the opening degree of the valve section 10 is set by the solenoid force of the solenoid section 20 and is changed by sensing the suction pressure Ps. A valve is configured to control the pressure Pc in the crank chamber so as to be constant.
[0020]
Next, the operation of the displacement control valve of the present invention will be described.
In the solenoid unit 20, the set value of the displacement control valve can be freely changed from the outside by controlling the duty ratio of the pulse current flowing through the electromagnetic coil 21. That is, when the duty ratio is increased and the average current value is increased, the force for attracting the plunger 24 to the core 23 is increased, the valve opening is set small, and when the duty ratio is reduced and the average current value is reduced, The valve opening is set large.
[0021]
Here, when a pulse current having a certain duty ratio is supplied to the electromagnetic coil 21 and the valve unit 10 has a certain valve opening, for example, if the suction pressure Ps decreases, the diaphragm 19 moves upward in the figure. The spool valve body 16 is displaced to drive the spool valve body 16 in the valve opening direction, and the valve opening degree increases. As a result, the flow rate of the refrigerant supplied to the crank chamber increases, the medium pressure Pc increases, and acts to reduce the inclination angle of the swash plate. Therefore, the stroke of the piston is shortened, the discharge capacity is reduced, and the suction capacity is reduced. An attempt is made to increase the pressure Ps.
[0022]
Conversely, when the suction pressure Ps increases, the diaphragm 19 is displaced downward in the figure to drive the spool valve body 16 in the valve closing direction, and the valve opening decreases. As a result, the flow rate of the refrigerant supplied to the crank chamber decreases, the medium pressure Pc decreases, and the inclination angle of the swash plate increases, so that the stroke of the piston increases, and the discharge capacity increases. An attempt is made to lower the suction pressure Ps.
[0023]
As the duty ratio of the pulse current flowing through the electromagnetic coil 21 increases, the spool valve body 16 moves in the valve closing direction. At this time, the spool valve element 16 approaches the valve seat 11b while making a slight vibration in the opening and closing direction of the valve. Alternatively, when the suction pressure Ps is increased and the spool valve body 16 is controlled in the valve closing direction when the spool valve body 16 is in the vicinity of the valve closing position, the spool valve body 16 similarly moves in the valve closing direction.
[0024]
However, even when the lower end of the spool valve element 16 reaches the valve seat 11b and passes through the valve seat 11b and is inserted into the valve hole, the spool valve element 16 does not contact the valve seat 11b. Therefore, there is no possibility that the spool valve body 16 collides with the valve seat 11b to open the valve for the stroke of the vibration. Further, when the duty ratio is maximized, the solenoid portion 20 has no force to push up the shaft 17, so that the spool valve body 16 is urged by the coil spring 15, and the tapered portion 16a is seated on the valve seat 11b, and the spool chamber 16 is moved from the discharge chamber. The flow path to the crankcase is completely closed.
[0025]
Therefore, the spool valve body 16 does not collide with the valve seat 11b and move in the valve opening direction just before the spool valve body 16 reaches the valve seat 11b. It is possible to make the lift characteristic until reaching 11b linear. Further, since the spool valve element 16 does not directly and repeatedly collide with the valve seat 11b, the durability of the spool valve element 16 and the valve seat 11b can be maintained.
[0026]
FIG. 2 is a cross-sectional view illustrating a displacement control valve according to the second embodiment. In FIG. 2, the same or equivalent components as those of the capacity control valve shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0027]
The difference from the first embodiment is that the discharge pressure Pd from the discharge chamber of the variable displacement compressor is applied to the spool valve body 16 in the valve closing direction, but is applied to the valve opening direction. Different. Therefore, the hole formed on the side surface of the body 11 constitutes the first port 11a for introducing the discharge pressure Pd, and the hole formed on the top of the body 11 constitutes the second port 11c for supplying the pressure Pc to the crank chamber. are doing. By exchanging the first and second ports 11a and 11c, the filter 13 is provided around the body 11 at the position where the first port 11a is formed.
[0028]
Also, in the capacity control valve according to the second embodiment, the operation and the effect are completely the same as those in FIG. 1 described above, and the description is omitted here.
[0029]
FIG. 3 is a sectional view showing a displacement control valve according to the third embodiment. In FIG. 3, the same or equivalent components as those of the capacity control valve shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0030]
The difference from the first embodiment is that the valve body of the valve section 10 and the shaft 17 for transmitting the movement of the diaphragm 19 to the valve body are separate bodies, and the valve body is a ball valve body 16b. This is different from the first embodiment in that the tip of the shaft 17 on the side that comes into contact with the ball valve body 16b is formed in a spool shape to form a spool valve.
[0031]
Also in this displacement control valve, immediately before the ball valve body 16b is seated on the valve seat 11b, the tip portion of the shaft 17 first enters the valve hole to bring the valve portion 10 into the valve closed state. Since the ball valve element 16b does not collide with the valve seat 11b and moves in the valve opening direction, the lift characteristics until the valve reaches the valve closed state can be made linear. When the duty ratio is changed to the maximum side, the off-time of the pulse current is shorter than the on-time, so that there is little micro-vibration in the axial direction of the shaft 17, and in this state, the ball valve body 16b Since the ball valve body 16b is seated on the seat 11b, the collision force when the ball valve body 16b is seated on the valve seat 11b is weakened, and the durability of the ball valve body 16b and the valve seat 11b can be improved.
[0032]
The operation and effect of the capacity control valve according to the third embodiment are also the same as those of FIG. 1 described above, and thus description thereof will be omitted.
In the above-described embodiment, the displacement control valve of the so-called input control in which the discharge pressure Pd is introduced into the crank chamber by using a valve structure as a spool valve has been described. However, the pressure Pc of the crank chamber is supplied to the suction chamber. The same can be applied to a capacity control valve which performs so-called release control, which is derived and controls the pressure Pc of the crank chamber, and furthermore, a capacity control valve which simultaneously performs input control and release control in conjunction with each other. it can.
[0033]
【The invention's effect】
As described above, in the present invention, the valve portion is configured as the spool valve that operates so that the valve element is inserted into and removed from the valve hole. As a result, the valve body and the valve seat do not collide in the vicinity of the valve closed position, so that the lift characteristics can be improved and the durability of the components can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a displacement control valve according to a first embodiment.
FIG. 2 is a sectional view showing a displacement control valve according to a second embodiment.
FIG. 3 is a sectional view showing a displacement control valve according to a third embodiment.
[Explanation of symbols]
Reference Signs List 10 Valve part 11 Body 11a First port 11b Valve seat 11c Second port 11d Third port 12 Pressure introduction chamber 13 Filter 14 Adjust screw 15 Coil spring 16 Spool valve body 16a Tapered part 16b Ball valve body 17 Shaft 18 Center disk 19 Diaphragm Reference Signs List 20 solenoid part 21 electromagnetic coil 22 sleeve 23 core 24 plunger 25 coil spring 26 shaft 27 bearing part Pc crank chamber pressure Pd discharge pressure Ps suction pressure

Claims (4)

In the displacement control valve of the variable displacement compressor, the valve opening is set by controlling the duty ratio of the pulse current supplied to the electromagnetic solenoid,
A displacement control valve for a variable displacement compressor, wherein a valve for controlling opening and closing of a passage between a first port into which the refrigerant is introduced and a second port from which the refrigerant is discharged is constituted by a spool valve. A valve seat formed in a passage between the first port and the second port; and a spool arranged to be removably inserted into a valve hole of the valve seat from an upstream side or a downstream side. A valve body, a spring for urging the spool valve body in a valve closing direction, and a shaft for transmitting the solenoid force of the electromagnetic solenoid to the spool valve body through the valve hole. The displacement control valve for a variable displacement compressor according to claim 1. A diaphragm disposed between the shaft of the valve section and the electromagnetic solenoid to sense the pressure introduced into the third port and control the spool valve body so that the pressure is constant. The displacement control valve for a variable displacement compressor according to claim 2, wherein The valve portion has a valve body as a ball valve body, and a tip of a shaft that transmits the solenoid force of the electromagnetic solenoid to the ball valve body through a valve hole, and has a tip end on a contact side with the ball valve body, and has a spool shape. 2. A displacement control valve for a variable displacement compressor according to claim 1, wherein said spool valve is configured.

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