CN1738971A - Control valve of variable displacement compressor - Google Patents

Abstract

A control valve of a variable displacement compressor capable of improving compression efficiency by reducing the circulated amount of refrigerant in the variable displacement compressor, comprising a ball valve (11) controlling the flow rate of the refrigerant flowing from a delivery chamber to a crank chamber, a spool valve (12) controlling the flow rate of the refrigerant flowing from the crank chamber to a suction chamber, a diaphragm (13) sensing a suction pressure (Ps), and a solenoid (14) setting the suction pressure, wherein the spool valve (12) is formed so as to start flow rate control after the ball valve (11) is fully closed or nearly fully closed and the ball valve (11) is formed so as to start flow rate control after the spool valve (12) is minimally opened or nearly minimally opened. Because an area in which the ball valve (11) and the spool valve (12) are simultaneously opened can be almost eliminated when the flow rate controls of these valves are switched, the flow rate of the refrigerant circulating inside the variable displacement compressor and not contributing to freezing action can be minimized to increase the efficiency of the variable displacement compressor.

Description

Control valves for variable capacity compressors

technical field

The invention relates to a control valve of a variable capacity compressor, in particular to a control valve of a variable capacity compressor used in the refrigeration cycle of an automobile air conditioner.

Background technique

In the air conditioner for automobiles, since the rotational speed of the engine as its power source is variable, it is necessary to control the air conditioner so that its cooling capacity is kept constant without being affected by the rotational speed of the engine. To meet such requirements, a swash plate type variable capacity compressor that can change the refrigerant discharge amount is generally used. The swash plate installed in the crankcase with a variable inclination angle performs a swing motion by the rotation of the rotation shaft, and through this swing motion, a plurality of pistons reciprocate in a direction parallel to the rotation shaft, whereby the variable capacity The compressor sucks in, compresses, and discharges the refrigerant. At this time, by changing the pressure in the crankcase by the control valve, the inclination angle of the swash plate is changed, and the stroke of the piston is changed, thereby changing the refrigerant discharge amount.

Such a control valve is usually arranged on the refrigerant passage connecting the discharge chamber and the crankcase, and controls the pressure Pc in the crankcase by controlling the flow rate of refrigerant having a discharge pressure Pd introduced from the discharge chamber to the crankcase. The refrigerant introduced into the crankcase is discharged into the suction chamber through a fixed orifice, and the control valve senses the suction pressure Ps in the suction chamber by using a pressure-sensitive component such as a diaphragm, and controls the refrigerant introduced into the crankcase flow to keep the suction pressure Ps constant.

In addition, the control valve can also be arranged on the refrigerant passage connecting the crankcase and the suction chamber, and a fixed orifice can be provided between the discharge chamber and the crankcase, so as to control the flow rate of the refrigerant discharged from the crankcase. control.

The variable capacity compressors using either of these two types of control valves are equipped with fixed orifices in series with constant passage area on the passage from the discharge chamber to the crankcase, or from the crankcase to the suction chamber. . Therefore, in the variable capacity compressor using one of the control valves, since the amount of refrigerant circulating therein increases, compression efficiency inevitably decreases.

There has also been proposed a control valve (for example, Japanese Patent Application Laid-Open No. 58-158382, FIG. 3 ), that is, a refrigerant passage connecting the discharge chamber and the crankcase, and a refrigerant passage connecting the crankcase and the suction chamber. Two valves are respectively arranged on the channels, and the two valves are operated in an interlocking manner so as to simultaneously control the flow of refrigerant flowing into the crankcase and the flow of refrigerant discharged from the crankcase. Thus, because of the control of the control valve, when the refrigerant flow rate of any one of the refrigerant passage connecting the discharge chamber and the crankcase and the refrigerant passage communicating the crankcase and the suction chamber increases, the On the other hand, since the flow rate is reduced, the flow rate of the refrigerant circulating inside the variable capacity compressor can be reduced, and a variable capacity compressor with high compression efficiency can be constructed by using the control valve having the above structure.

In addition, a control valve of the following scheme has also been proposed (for example, Japanese Patent Laying-Open No. 64-41680, FIG. 2 ), which is constituted by: connecting the discharge chamber with the crankcase and the refrigerant passage connecting the crankcase and the suction chamber Two valves are respectively arranged on the refrigerant passages of the two valves, and these two valves are operated in an interlocking manner, so that when one of the refrigeration passages is opened and in a controlled state, the other refrigeration passage will be closed. Therefore, since the control valve controls the flow rate of one of the refrigeration passages, the other refrigeration passage is closed, so the refrigerant circulating inside the variable capacity compressor can be further reduced.

However, for the aforementioned control valve described in Japanese Patent Laid-Open No. 58-158382, in which the crankcase is provided with valves on the inlet side and the outlet side respectively, among the two valves that act in a linked manner, because one of them is Since the other valve is opened when it is closed, there must be an area where both valves are open, so the refrigerant flow rate circulating inside the compressor can only be reduced to a certain extent, and there is a problem that the compression efficiency cannot be sufficiently improved.

In addition, in the latter control valve described in Japanese Patent Application Laid-Open No. 64-41680, when one of the valves is opened and the other valve is closed, when the suction pressure decreases to less than or equal to the first set pressure, because the crankcase and The refrigerant passage (outlet side) between the suction plenums is completely closed, so the pressure in the crankcase responds sensitively to small changes in the valve of the refrigerant passage (inlet side) between the discharge space and the crankcase. However, when the pressure in the crankcase rises transiently, even if the opening of the valve on the inlet side is changed, the gas refrigerant remaining in the crankcase cannot be reduced. When the pressure naturally rises to be greater than or equal to the second set pressure, the refrigerant channel on the outlet side is opened, and the pressure in the crankcase is gradually reduced. And, as the pressure in the crankcase decreases, the discharge amount increases, the suction pressure decreases to less than or equal to the first set pressure, and the cycle is repeated again, that is, a hunting phenomenon occurs. As described above, in the structure of the latter control valve, there is a problem that stable control performance cannot be obtained.

content of the invention,

The present invention is made in view of the above problems, and its object is to provide a control valve of a variable capacity compressor that can obtain stable control performance and reduce the amount of refrigerant circulation inside the variable capacity compressor, thereby improving Compression efficiency.

In order to solve the above problems, the present invention provides a control valve of a variable capacity compressor, which can change the discharge amount of refrigerant by controlling the pressure in the crankcase, which has: a first valve , arranged between the discharge chamber of the variable capacity compressor and the crankcase, for controlling the refrigerant flow from the discharge chamber to the crankcase; the second valve, arranged in the crankcase and the suction chamber of the variable capacity compressor, for allowing refrigerant to flow from the crankcase to the crankcase when the first valve controls the flow of refrigerant from the discharge chamber to the crankcase The flow of refrigerant in the suction chamber is controlled to a minimum predetermined amount, and is used to control the flow of refrigerant flowing from the crankcase to the suction chamber when the first valve is completely closed or nearly completely closed and a pressure sensing part, sensing the suction pressure of the suction chamber, so as to change the lifting amount of the first valve and the second valve.

According to the control valve of such a variable capacity compressor, the second valve that controls the flow rate of the refrigerant flowing from the crankcase to the suction chamber of the variable capacity compressor, after the first valve is completely closed or nearly completely closed, The flow control is started, and the flow control of the first valve is started after the second valve becomes to the minimum opening degree or close to the minimum opening degree. With this structure, the flow rate of the refrigerant that flows from the discharge chamber to the crankcase and then from the crankcase to the suction chamber, that is, the refrigerant that circulates inside the variable capacity compressor without cooling The flow rate is kept to a minimum and the pressure in the crankcase is restrained from rising too sensitively. As a result, stable controllability can be obtained, and compression efficiency can be improved.

The above and other objects, features, and advantages of the present invention will be clarified by the following description associated with the drawings showing preferred embodiments as examples of the present invention.

Description of drawings

Fig. 1 is a schematic diagram showing the structure of a control valve of a variable displacement compressor according to the present invention.

Fig. 2 is a partially enlarged explanatory view showing a control valve set to a first opening and closing time.

Fig. 3 is a graph showing characteristics of a control valve set to a first opening and closing time.

Fig. 4 is a partially enlarged explanatory view showing a control valve set to a second opening and closing time.

Fig. 5 is a graph showing characteristics of a control valve set to a second opening and closing time.

Fig. 6 is a partially enlarged explanatory view showing a control valve set to a third opening and closing time.

FIG. 7 is a graph showing characteristics of a control valve set to a third opening and closing time.

Fig. 8 is a partially enlarged explanatory diagram showing a control valve having fixed orifices formed on the inlet side and the outlet side.

FIG. 9 is a graph showing characteristics of a control valve set to a fourth opening and closing time.

Fig. 10 is a schematic diagram showing a control valve having fixed orifices formed on the inlet side and the outlet side.

FIG. 11 is a graph showing characteristics of a control valve set to a fifth opening and closing time.

Fig. 12 is a schematic diagram showing the structure of a mechanical control valve of a variable capacity compressor.

Fig. 13 is a schematic diagram showing the structure of a mechanical control valve of a variable capacity compressor.

14 is a schematic diagram showing the structure of a mechanical control valve of a variable capacity compressor in which the function of the fixed orifice of the second valve is independent.

Detailed ways

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a schematic diagram showing the structure of a control valve of a variable displacement compressor according to the present invention.

The control valve of the variable capacity compressor of the present invention is arranged in the following order: the ball valve 11 constituting the first valve, the slide valve 12 constituting the second valve, the diaphragm 13 constituting the pressure sensing part, and the valve constituting the pressure setting part. solenoid (solenoid)14.

The ball valve 11 introduces refrigerant at a discharge pressure Pd from a discharge chamber of the variable capacity compressor, and controls the flow rate of the introduced refrigerant to supply refrigerant at a pressure Pc1 to the crankcase of the variable capacity compressor. The slide valve 12 introduces refrigerant at a pressure Pc2 from the crankcase, and controls the flow rate of the refrigerant supplied to the suction chamber of the variable capacity compressor in conjunction with the operation of the ball valve 11 . The diaphragm 13 bears the suction pressure Ps of the suction chamber. If the suction pressure is lower than the predetermined suction pressure set point, the diaphragm 13 will change the position of the ball valve 11 and the slide valve 12 to increase the pressure in the crankcase. By increasing the pressure in the crankcase, the discharge of the compressor is reduced, and as a result, the suction pressure of the air conditioner is controlled around a predetermined suction pressure set point. The solenoid 14 applies an urging load to the diaphragm 13, which is set according to the value of the current supplied from the outside, thereby setting the suction pressure set point.

The spool valve 12 has a valve seat 15 and a valve body 16 which is freely pluggable relative to the valve hole, and a predetermined gap 17 is provided between the valve seat 15 and the valve body 16 . When the valve body 16 is inserted into the valve hole, the gap 17 constitutes a fixed orifice with a constant channel area between the crankcase and the suction chamber, and the gap 17 is determined by the stability of the swash plate of the variable capacity compressor. to decide. Also, the valve body 16 is integrally formed with a shaft 18 for driving the ball valve 11 , and the valve body 16 and the shaft 18 are joined by a frustoconical joining portion 19 having a tapered cross section.

The spool valve 12 can be freely changed so as to have an opening and closing time different from the opening and closing time of the ball valve 11 corresponding to the characteristics of the variable capacity compressor such as oscillation, controllability, and stability. The operation of valve 12 is linked. By changing the distance between the end of the valve body 16 as a boundary with the engaging portion 19 and the end of the shaft 18 of the valve body 20 contacting the ball valve 11, the position of the end of the valve body 16 when the ball valve 11 is fully closed is along the axis The opening and closing time of the ball valve 12 can be easily changed by changing the direction.

In addition, the ball valve 11 moves the shaft 18 to the right in FIG. 1 to move the valve body 20 in the opening direction, and the step portion 21 provided on the shaft 18 comes into contact with the step portion 22 formed on the main body. Limit the maximum opening of the ball valve 11.

FIG. 2 is a partially enlarged explanatory view showing a control valve set to a first opening and closing time, and FIG. 3 is a diagram showing characteristics of a control valve set to a first opening and closing time.

The first opening and closing time is the time to make the opening and closing time of the ball valve 11 consistent with the opening and closing time of the slide valve 12. When the ball valve 11 is completely closed, the end of the valve body 16 of the slide valve 12 and the solenoid valve of the valve seat 15 The open ends on one side remain aligned.

Thus, when the valve body 16 of the spool valve 12 moves in the axial direction, the characteristics of the control valve are as shown in FIG. 3 . In FIG. 3 , the horizontal axis represents the stroke of the shaft 18, and the origin represents the time when the stepped portion 21 of the shaft 18 abuts against the stepped portion 22 of the main body and is located at the position closest to the ball valve 11 side (or the solenoid does not when powered on). The vertical axis of FIG. 3 represents the opening area of the ball valve 11 and the spool valve 12 . Also, a line indicated by Pd-Pc indicates a change in the opening area of the ball valve 11 , and a line indicated by Pc-Ps indicates a change in the opening area of the spool valve 12 .

For this first opening and closing time, during the opening of the ball valve 11 , the spool valve 12 has an opening area equivalent to the gap 17 and serves as a fixed orifice. When the shaft 18 is moved toward the solenoid 14 side to reach the position s1 , the ball valve 11 is completely closed by the seating of its valve body 20 . When the shaft 18 moves further to the solenoid 14 side, the end of the shaft 18 leaves the valve body 20 of the ball valve 11, the ball valve 11 remains in a fully closed state, and the spool valve 12 starts to open from the state as a fixed throttle, and its opening The area gradually increases corresponding to the stroke of the shaft 18 . When the ball valve 11 is fully closed, the refrigerant compressed by the control valve does not flow into the crankcase, but passes between the piston which sucks in and compresses the refrigerant and the cylinder in which the piston is slidably received. A small amount of blow-by gas leaks into the crankcase through the clearance, thereby controlling the pressure Pc (=Pc1=Pc2) in the crankcase.

FIG. 4 is a partially enlarged explanatory view showing a control valve set to a second opening and closing time, and FIG. 5 is a diagram showing characteristics of a control valve set to a second opening and closing time.

The second opening and closing time is the time to delay the opening time of the spool valve 12 from the closing time of the ball valve 11. When the ball valve 11 is fully closed, the spool valve 12 is still in the closed state (fixed orifice state). For this reason, compared with the situation of the first opening and closing time, only the distance a is reduced between the end of the ball valve 11 side of the valve body 16 and the end of the shaft abutting on the valve body 20 of the ball valve 11, thereby When the ball valve 11 is closed, the end of the valve body 16 of the slide valve 12 close to the ball valve 11 is located in the valve hole.

Thus, for the second opening and closing time, as shown in FIG. 5 , if the shaft 18 moves toward the solenoid 14 side, first the ball valve 11 is completely closed when the shaft 18 reaches the position s1 . At this time, the spool valve 12 has an opening area corresponding to the gap 17 . When the shaft 18 moves further toward the solenoid 14 and reaches the position s2, the spool valve 12 starts to open.

FIG. 6 is a partially enlarged explanatory diagram showing a control valve set to a third opening and closing time, and FIG. 7 is a diagram showing characteristics of a control valve set to a third opening and closing time.

This third opening and closing time is a time at which the opening time of the spool valve 12 is made earlier than the closing time of the ball valve 11 . For this reason, compared with the situation of the first opening and closing time, the distance between the end of the valve body 16 near the ball valve 11 side and the end of the shaft abutting on the valve body 20 of the ball valve 11 is only increased by distance b, When the ball valve 11 is closed, the end of the valve body 16 of the spool valve 12 on the ball valve 11 side is made closer to the solenoid 14 side than the valve seat 15 is.

Thus, for the third opening and closing time, as shown in FIG. 7, when the shaft 18 moves toward the solenoid 14 side, when the shaft 18 hits the position s1, the spool valve 12 first starts to open, and then when the shaft 18 reaches the position At s2, the ball valve 11 is completely closed.

8 is a partially enlarged explanatory diagram showing a control valve having fixed orifices formed on the inlet side and the outlet side, and FIG. 9 is a diagram showing characteristics of the control valve set to a fourth opening and closing time. In addition, in FIG. 8 , the same reference numerals are given to the same components as those shown in FIG. 1 .

In this control valve, fixed orifices are formed on both the inlet side and the outlet side of the crankcase. In this control valve, the end portion of the shaft 18 on the side of the valve body 20 that abuts on the ball valve 11 is formed in the shape of a scroll, and there is a gap between the outer circumference of the abutting end portion 23 that abuts on the valve body 20 and the inner wall of the valve hole. twenty four. When the ball valve 11 is close to fully closed, the gap 24 is located in the valve hole to form a fixed orifice with a constant passage area between the compression chamber and the crankcase. The fixed orifice is located in a region where refrigerant is introduced into the crankcase through blow-by air and the flow rate of refrigerant discharged from the crankcase is controlled by the slide valve 12, and is used to stably maintain refrigerant introduced from the discharge chamber to the crankcase. refrigerant flow. The distance between the rear end of the abutting end portion 23 (the position where the diameter starts to be reduced) and the seating position of the valve body 20 is a distance c. Also, in the present embodiment, when the ball valve 11 is fully closed and the valve body 20 remains in abutment on the abutment end portion 23, the distance between the end of the valve body 16 of the spool valve 12 and the valve closing start position of the spool valve 12 The distance d is set to the same value as the distance c.

Such a control valve has the following characteristics: as shown in Figure 9, first when the solenoid is not energized, because the stepped portion 21 of the shaft 18 abuts on the stepped portion 22 of the main body, the ball valve 11 is in a fully open state, and the slide Valve 12 is in a fixed orifice state.

By increasing the energizing current of the solenoid, the ball valve 11 changes from the fully open state to the direction of reducing the opening area, and the spool valve 12 maintains a fixed orifice state. Then, when the shaft 18 moves to the position s1, the rear end of the abutment end 23 reaches the seating position of the valve body 20, and the valve body 16 of the spool valve 12 reaches the valve opening position away from the fixed orifice state. When the shaft 18 moves further from the position s1, the rear end of the abutting end portion 23 enters the valve hole and becomes a state of a fixed orifice, and the spool valve 12 changes from the state of a fixed orifice to a direction of increasing the opening area.

Then, the state of the fixed orifice of the ball valve 11 is maintained until the opening area of the ball valve 11 is smaller than that of the fixed orifice, and finally the ball valve 11 is seated to become a fully closed state.

Here, the distance c and the distance d have the same value, but the opening and closing time of the slide valve 12 can be easily changed by increasing or decreasing the distance d according to the characteristics of the variable displacement compressor.

FIG. 10 is a schematic diagram showing a control valve having fixed orifices formed on the inlet side and the outlet side, and FIG. 11 is a diagram showing characteristics of the control valve set to a fifth opening and closing time. In addition, in FIG. 10 , the same reference numerals are assigned to the same components as those shown in FIG. 1 .

Of the control valves, the valves arranged between the compressor and the crankcase and the valves arranged between the crankcase and the suction chamber are constituted by corresponding slide valves 11 a and 12 . The valve body 16 of the spool valve 12, the shaft 18, and the valve body 20a of the spool valve 11a are integrally formed. There is a gap 24 between them. In addition, the diameter of the portion between the valve body 20a and the shaft 18 is reduced to form a scroll shape. And, when the spool valve 12 is at the valve closing start position, there is a distance e between the rear end of the valve body 20a (the position where the diameter starts to decrease) and the valve closing start position where the valve body 20a enters the valve hole.

The control valve at this time has the following characteristics: As shown in FIG. 11, first, when the solenoid is not energized, because the stepped portion 21 of the shaft 18 abuts on the stepped portion 22 of the main body, the spool valve 11a is in a fully open state. , and the spool valve 12 is completely closed and is in a state of a fixed throttle.

By increasing the energizing current of the solenoid, the rear end of the valve body 20a of the spool valve 11a approaches the valve hole and changes from a fully open state to a direction of reducing the opening area, while the spool valve 12 maintains a fixed orifice state. Next, when the shaft 18 moves to the position s1, the spool valve 11a reaches the valve closing start position, and the valve body 16 of the spool valve 12 reaches the opening start position away from the fixed orifice state. When the shaft 18 moves further from the position s1, the valve body 20a enters the valve hole, so that the spool valve 11a becomes a fixed orifice state and maintains this state, and the spool valve 12 changes from the fixed orifice state to the direction of increasing the opening area .

In the above embodiments, the electric control valve has been described. As the device for setting the suction pressure Ps of the suction chamber, the control valve uses a set value (pressure pressure Ps) that can be freely set by the control current from the outside. control point) of the solenoid. Next, a mechanical control valve in which the suction pressure Ps is set to a fixed value will be described.

Fig. 12 is a schematic diagram showing the structure of a mechanical control valve of a variable displacement compressor. In addition, in FIG. 12 , the same components as those shown in FIG. 1 are assigned the same reference numerals, and detailed description thereof will be omitted.

The control valve is arranged in the following order: a ball valve 11 constituting a first valve, a spool valve 12 constituting a second valve, a diaphragm 13 constituting a pressure sensing portion, and a spring 25 constituting a pressure setting portion.

This control valve is also configured such that the spool valve 12 serves as a fixed orifice while the ball valve 11 controls its opening area to be variable, and the spool valve 12 controls its opening area to be variable when the ball valve 11 is in a fully closed state. Of course, corresponding to the characteristics of the variable capacity compressor, the opening and closing time of the slide valve 12 can be set to any one of the first to third opening and closing times.

The surface of the membrane 13 on the side of the spring 25 is equipped with a disk 26 , by means of which the spring 25 pushes the membrane 13 in the direction of the slide valve 12 . The spring 25 is adjusted to have an elastic load corresponding to a predetermined suction pressure control point. Therefore, when the suction pressure Ps from the suction chamber is lower than the predetermined suction pressure control point, the diaphragm 13 exerts a load on the ball valve 11 and the slide valve 12, so that the pressure of the crankcase rises, and the control valve is controlled variable accordingly. The displacement of the capacity compressor, so as to control the suction pressure of the air conditioner near the predetermined suction pressure control point.

Of course, the control valve can also be configured as a control valve with a fourth opening and closing time, that is, by forming an abutment end portion 23 at the end of the shaft 18 to form a fixed throttle as shown in FIG. 8 , so that the crankcase Fixed orifices are formed on each of the refrigerant inlet and outlet sides.

Fig. 13 is a schematic diagram showing the structure of a mechanical control valve of a variable displacement compressor. In addition, in FIG. 13 , the same components as those shown in FIGS. 1 and 10 are denoted by the same reference numerals, and detailed description thereof will be omitted.

This control valve is arranged in the following order: a spool valve 11a constituting a first valve, a spool valve 12 constituting a second valve, a diaphragm 13 constituting a pressure sensing portion, and a spring 25 constituting a pressure setting portion.

The spool valve 11 a has the same structure as the valve shown in FIG. 10 , so that the current control valve has the characteristic of the fifth opening and closing time shown in FIG. 11 .

The control valve is also subjected to the suction pressure Ps from the suction chamber to lift the cover plates of the spool valves 11a, 12 to control the pressure in the crankcase so that the suction pressure Ps is kept constant.

Fig. 14 is a schematic diagram showing the structure of the control valve of the variable capacity compressor, in which the role of the fixed orifice of the second valve is independent. In addition, in FIG. 14, the same code|symbol is attached|subjected to the same component as the component shown in FIG. 1, and the detailed description is abbreviate|omitted.

The control valve shown in Figure 1 utilizes the gap 17 provided between the valve body 16 of the spool valve 12 and the inner wall of the valve hole to provide the function of a fixed orifice. Unlike this, the current control valve is formed in the main body with the same The fixed orifice 27 with the same opening area formed by the gap 17 is used. In this case, the gap 17 provided between the valve body 16 and the inner wall of the valve bore is minimized. Thus, when the refrigerant passage between the crankcase and the suction chamber is narrowed by the spool valve 12, the refrigerant flows to the side of the larger-diameter fixed orifice 27 instead of to the smaller gap 17. As a result, there is an effect that the change in flow rate of the refrigerant can be reduced by precipitating sludge contained in the refrigerant.

That is, if the gap 17 between the valve body 16 of the spool valve 12 and the inner wall of the valve hole is, for example, 0.1 mm, the fixed orifice 27 having an opening area equal to the gap 17 is a hole with a diameter of 1 mm, and the sediment For example, if the sludge on the inner wall of the valve body 16 or the valve hole or the inner wall of the fixed orifice 27 accumulates to a thickness of 0.1 mm, the gap 17 is almost blocked by the sludge, so that the diameter of the fixed orifice 27 is reduced to only It is 0.8mm, which makes the change of the refrigerant flow rate caused by sludge precipitation small. In addition, since the refrigerant mainly flows through the fixed orifice 27 which is easy to flow, there is an advantage that the amount of refrigerant flowing through the narrow gap 17 is small and sludge is less likely to be deposited.

In addition, the structure in which the fixed orifice 27 is arranged in parallel with the spool valve 12 constituting the second valve has been described as an example of the case where it is applied to the control valve having the solenoid 14 shown in FIG. 12 and the mechanical control valves shown in Fig. 13 are also applicable.

As described above, in the present invention, the control valve is constituted to include: a first valve for controlling the flow rate of refrigerant flowing from the discharge chamber to the crankcase; a second valve for controlling the flow rate of refrigerant flowing from the crankcase to the suction chamber. The flow rate of the refrigerant; the pressure sensing part for sensing the suction pressure; and the pressure setting part for setting the suction pressure Ps. After the first valve is completely closed or nearly completely closed, the second valve starts to perform flow control, and after the second valve becomes to a minimum opening or close to the minimum opening, the first valve starts to perform flow control. Thus, when the control of the first valve and the second valve is switched, since there is no region where the first valve and the second valve are simultaneously opened, it is possible to transfer the flow from the discharge chamber to the crankcase, and then from the crankcase to the suction. The flow rate of the refrigerant that flows through the chamber, that is, the flow rate of the refrigerant that circulates in the variable capacity compressor without cooling is controlled to a minimum, so that the efficiency of the variable capacity compressor can be improved. Furthermore, since the second valve has a fixed orifice function to make the flow rate of the refrigerant flowing from the crankcase into the suction chamber a minimum predetermined flow rate, the pressure in the crankcase can be stably adjusted, thereby obtaining excellent control performance.

What has been described is merely indicative of the principles of the invention. For those skilled in the art, various deformations and modifications can be made. The present invention is not limited to the specific structures and application examples shown and illustrated. All suitable modifications and equivalent solutions can be considered as falling within the scope of the appended claims. claims and their equivalents form the scope of this invention.

Claims (12)

1. A control valve of a variable capacity compressor, which can change the discharge amount of refrigerant by controlling the pressure in the crankcase, characterized in that it has: a first valve, arranged between the discharge chamber of the variable capacity compressor and the crankcase, for controlling the flow of refrigerant flowing from the discharge chamber to the crankcase; a second valve disposed between the crankcase and a suction chamber of the variable capacity compressor, and used when the first valve controls the flow of refrigerant flowing from the discharge chamber to the crankcase , to control the flow of refrigerant flowing from the crankcase to the suction chamber to a minimum predetermined amount, and to control the flow of refrigerant from the crankcase to the suction chamber when the first valve is completely closed or nearly completely closed the flow rate of refrigerant in the suction chamber; The pressure sensing part senses the suction pressure of the suction chamber, so as to change the lifting amount of the first valve and the second valve. 2. The control valve of the variable capacity compressor according to claim 1, characterized in that, The second valve has a clearance provided between a diameter of the valve hole and a diameter of the valve body, the clearance having a clearance for controlling the flow rate of refrigerant flowing from the crankcase to the suction chamber to a minimum predetermined amount. A fixed orifice function wherein the valve body is inserted into the valve hole when the first valve controls the flow of refrigerant from the discharge chamber to the crankcase. 3. The control valve of the variable capacity compressor according to claim 1 or 2, characterized in that, The control valve has a shaft, which extends through the valve hole of the second valve and is on the same axis as the valve hole, for transmitting the opening and closing action of the second valve to the first valve . 4. The control valve of the variable capacity compressor according to claim 3, characterized in that, The shaft has an engagement portion engaged with the valve body, the engagement portion being formed in a frusto-conical shape. 5. The control valve of the variable capacity compressor according to claim 3, characterized in that, An end portion of the shaft abuts against the valve body of the first valve and is formed such that the end portion has a scroll shape. 6. The control valve of a variable capacity compressor according to claim 3, wherein: The shaft may be in contact with and separated from the valve body of the first valve. 7. The control valve of the variable capacity compressor according to claim 3, characterized in that, A gap is provided between the diameter of the end portion of the shaft which abuts on the valve body of the first valve and the valve hole of the first valve, the gap having the capacity to flow from the discharge chamber to the crankshaft. The refrigerant flow control of the tank is a fixed orifice function of a predetermined minimum amount. 8. The control valve of the variable capacity compressor according to claim 1, characterized in that, The first valve is a spool valve. 9. The control valve of a variable capacity compressor according to claim 1, wherein: The control valve has a fixed orifice which is arranged in parallel with the second valve and which will flow from the crankshaft when the first valve controls the flow of refrigerant from the discharge chamber to the crankcase. Refrigerant flow from the tank to the suction chamber is controlled to a minimum predetermined amount. 10. The control valve of a variable capacity compressor according to any one of claims 1 to 9, characterized in that, The control valve has a pressure setting portion that applies an actuation load to the pressure sensing portion to set a pressure control point of the control valve. 11. The control valve of the variable capacity compressor according to claim 10, characterized in that, The pressure setting part is a solenoid that sets the pressure control point by applying an actuation load according to an external signal. 12. The control valve of the variable capacity compressor according to claim 10, characterized in that, The pressure setting part is a spring that sets the pressure control point by elastic force.

Images