JP2001065455A - Control valve for variable displacement compressor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a simple structure and excellent reliability of opening / closing operation of a valve body, without increasing the number of parts and assembling man-hours, and without complicating a passage structure. SOLUTION: A communication passage 34 connected to a valve rod 42 slidably fitted in a valve rod engagement hole 35 formed in a valve housing 31 and communicating between a suction port of a compressor and a crank chamber is opened and closed. The ball valve element 40 is urged in the valve closing direction by the compression coil spring 54. The suction pressure of the compressor is applied to the diaphragm chamber 49, and a diaphragm device 43 that drives the ball valve body 40 in the valve opening direction via the valve rod 42 is connected to the valve rod 42. The pressure receiving surface 55 in the valve opening direction by the step end face is
2 and a discharge pressure passage 36 for guiding the discharge pressure of the compressor as a correction pressure to the valve housing 31.
An internal communication hole 57 is formed in the valve housing 31 for communicating between the compressor suction port side of the communication passage 34 and the diaphragm chamber 49.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control valve for a variable displacement compressor, and more particularly, to a displacement control valve for a swash plate type variable displacement compressor used in a vehicle air conditioner or the like.

[0002]

2. Description of the Related Art As a capacity control valve for a swash plate type variable displacement compressor, Japanese Patent Publication No. 3-53474 and Japanese Utility Model Publication No.
A capacity control valve disclosed in JP-A-17010 and JP-A-8-177735 is conventionally known.

[0003] This displacement control valve basically reduces the displacement in response to a rise in the pressure in the crankcase of a compressor incorporating a swash plate, and increases the displacement in response to a decrease in the pressure in the crankcase. In a variable displacement type compressor, a communication passage communicating a suction port of the compressor with a crank chamber is opened and closed by a valve element responsive to the suction pressure of the compressor, and the suction pressure of the compressor is supplied to the crank chamber. A control valve that controls the discharge pressure of the compressor in the valve opening direction, shifts the opening / closing operation point of the valve element according to the discharge pressure, and correlates with the outside air load (discharge pressure). It is configured to perform control.

[0004]

The above-mentioned conventional capacity control valves all achieve the desired purpose uniformly, however, because of the support structure of the valve body, the opening and closing operation of the valve body is not possible. Lacks certainty, increases the number of parts and assembly man-hours,
When the compressor is directly incorporated in the compressor housing, the passage structure for guiding the suction pressure and the discharge pressure to each part of the displacement control valve becomes complicated, and the degree of freedom of the arrangement position in the compressor housing is limited. Nothing can be fully satisfied.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. The structure is simplified, the opening and closing operation of the valve body is excellent, and the number of parts and the number of assembly steps are not increased. It is another object of the present invention to provide a control valve for a variable displacement compressor that is of a compressor housing built-in type and does not complicate the passage structure and has excellent flexibility in arrangement position in the compressor housing. .

[0006]

In order to achieve the above object, a control valve for a variable displacement compressor according to the first aspect of the present invention provides a communication passage for communicating a suction port of the compressor with a crank chamber. A valve housing provided in the valve housing for opening and closing the communication passage, and slidably fitted in a valve rod engaging hole formed in the valve housing;
A valve stem having one end connected to the valve body, a spring for urging the valve body in a valve closing direction, and the compression fixed to the valve housing and connected to the other end of the valve stem to exert on the diaphragm chamber. A diaphragm device for driving the valve body in the valve opening direction via the valve rod by the suction pressure of the machine, wherein a valve opening direction pressure receiving surface is formed in an intermediate portion of the valve rod, and an intermediate portion of the valve housing is provided. In the valve opening direction pressure receiving surface, a discharge pressure passage for guiding the discharge pressure of the compressor as a correction pressure in the valve opening direction of the valve element is formed, and the communication passage is formed inside the valve housing. An internal communication hole that connects the suction port side of the compressor to the diaphragm chamber is formed.

According to the control valve for a variable displacement compressor according to the first aspect of the present invention, a pressure-receiving surface in the valve-opening direction is formed in an intermediate portion of the valve rod, and the pressure-receiving surface in the valve-opening direction is formed in the middle of the valve housing. The discharge pressure of the compressor is given from a discharge pressure passage formed in the section, and a high pressure influence characteristic (discharge pressure influence characteristic) corresponding to the compressor discharge pressure correlated with the system load characteristic is set.

The valve body is connected to the valve stem, and the valve stem is slidably fitted in the valve housing valve stem engaging hole, so that the valve body does not move sideways with respect to the valve housing. . The suction pressure of the compressor is applied to the diaphragm chamber from the compressor suction port side of the communication passage by an internal communication hole formed inside the valve housing.

According to a second aspect of the present invention, in the control valve for a variable displacement compressor, the pressure-receiving surface in the valve opening direction is formed on a valve stem portion of the valve stem that is exposed to the discharge pressure passage. The valve opening side of the valve body is formed by the end face of the step portion having a larger diameter than the valve closing side.

According to the control valve for a variable displacement compressor according to the second aspect of the present invention, the valve rod portion of the valve rod exposed to the discharge pressure passage of the valve housing has the valve opening side closer to the valve opening side than the valve closing side. By forming a large-diameter stepped portion, a pressure-receiving surface in the valve-opening direction is formed at an intermediate portion of the valve stem by its end face.

[0011]

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

FIG. 1 shows a variable displacement compressor incorporating a control valve according to the present invention, and FIG. 2 shows a displacement control valve according to the present invention.

The swash plate type variable displacement compressor 1 includes a crank chamber 3 defined by a compressor housing 2 and a plurality of cylinder chambers 4 each communicating with the crank chamber 3 at one stroke end. Have. A piston 5 is fitted in each of the cylinder chambers 4 so as to be slidable in the axial direction. One end of a piston rod 6 is connected to the side of the crank chamber 3 of each piston 5.

The compressor housing 2 rotatably supports a drive shaft 7. The drive shaft 7 is drivingly connected to an engine (not shown) by a drive belt (not shown) stretched over a pulley 8. Is driven to rotate.

The drive shaft 7 is connected to a wobble plate (swash plate) 9 in the crank chamber 3 by a known connecting mechanism (not shown) in a torque transmitting relationship so that the mounting angle can be changed.
The piston rod 6 is engaged with the plate surface of the wobble plate 9 on the cylinder chamber 4 side so as to be able to transmit an axial force.

When the wobble plate 9 is rotationally driven by the drive shaft 7 in an inclined state, the piston 5 of each cylinder chamber 4 reciprocates with a stroke corresponding to the inclination angle of the wobble plate 9, and the inclination angle is determined by the crank angle. The pressure is automatically adjusted in accordance with the pressure difference between the chamber pressure Pc and the suction pressure (compressor suction pressure) Ps of each cylinder chamber 4.

In this case, the compressor 1 has a crank chamber pressure P
c, the inclination angle of the wobble plate 9 is reduced and the stroke of the piston 5 is reduced to reduce the displacement, and the wobble plate 9 is reduced in response to the decrease in the crank chamber pressure Pc.
As the stroke of the piston 5 increases and the stroke of the piston 5 increases, the displacement increases, and the crank chamber pressure Pc becomes substantially equal to the suction pressure Ps, whereby the engine enters a full load operation state.

Each cylinder chamber 4 is formed with a suction port 14 having a one-way valve and a suction port 14 having a discharge valve 13 and a discharge port 15. The suction port 14 of each cylinder chamber 4 is formed by a suction passage 16. The suction port 17 communicates with the suction port 17, and the discharge port 15 communicates with the discharge connection port 19 through the discharge passage 18. The evaporator 20, the expansion valve 21, the condenser 22, and the like are connected to the suction connection port 17 and the discharge connection port 19. Is connected.

A control valve receiving hole 23 having a bottomed hole is formed in the compressor housing 2.
The control valve 30 according to the present invention is inserted and fixed therein.

The control valve 30 has a cylindrical valve housing 31 inserted into the control valve receiving hole 23.

The valve housing 31 includes a valve housing 31.
Extends in the axial direction (vertical direction), and extends radially across the intermediate portion between the crank chamber side passage 32 and the valve housing 31 that is opened at one end surface (upper end surface) of the valve housing 31. A T-shaped communication passage 34 formed by the suction port side passage 33 and one end communicates with an intersection of the crank chamber side passage 32 and the suction port side passage 33, and extends axially through the center of the valve housing 31. A stepped valve stem engaging hole 35 opened at the other end surface (lower end surface) of the valve housing 31;
A discharge pressure passage 36 extending radially across an intermediate portion of the valve housing 31, specifically, a large diameter portion 35a of the valve rod engaging hole 35 is formed.

A filter 58 is mounted on the upper end surface of the valve housing 31 so as to cover the open end of the passage 32 on the crank chamber side.

An annular peripheral groove 37 for the suction port side passage 33 and an annular peripheral groove 38 for the discharge pressure passage 36 are formed in the outer peripheral portion of the valve housing 31.

The small diameter portion 35b of the valve rod engaging hole 35 is
4, the small diameter portion 35b and the crank chamber side passage 3
A ball valve body 40 is disposed in a valve chamber 39 defined by the intersection of the suction port 2 and the suction port side passage 33. The ball valve element 40 opens and closes the communication passage 34 by selectively seating on the valve seat 41 in the valve housing 31.

A valve rod 42 is fitted in the valve rod engaging hole 35 so as to be slidable in the axial direction. The valve stem 42 has a valve stem engagement hole 35.
Large diameter portion 42a and small diameter portion 35b fitted into large diameter portion 35a
And a stepped valve shaft having a small-diameter portion 42b that fits with the ball valve body 40 at the tip (one end of the valve rod) of the small-diameter portion 42b.

The other end (lower end) of the valve housing 31 is on the open end side of the control valve receiving hole 23 of the compressor housing 2, and the other end is exposed to the outside through the control valve receiving hole 23. A diaphragm device 43 is fixedly mounted.

The diaphragm device 43 includes the valve housing 3
1, a dish-shaped upper lid 44 which is swaged to the other end, a dish-shaped lower lid 46 which is joined to the upper lid 44 with a diaphragm 45 interposed therebetween, and a cylindrical spring box 4 which is swaged to the lower lid 46.
7 and an adjusting screw 48 threadedly engaged with the spring box 47.

The diaphragm 45 defines a diaphragm chamber 49 on the valve housing 31 side and a closed chamber 50 on the spring box 47 side with the diaphragm 45 interposed therebetween, and the large diameter portion of the valve stem 42 on the diaphragm chamber 49 side. 42a is connected to the tip (corresponding to the other end of the valve stem in the claims).

A contact 51, a ball 52, and a spring receiving member 53 are provided in this order on the closed chamber 50 side of the diaphragm 45. Between the spring receiving member 53 and the adjusting screw 48, the diaphragm 45, the valve stem 42, and the like are provided. A compression coil spring 54 is provided to urge the ball valve body 40 in the valve closing direction (upward) via the valve.

A valve-opening-direction pressure-receiving surface 55 is formed in the middle portion of the valve stem 42 by the large-diameter portion 42a and the small-diameter portion 42b. The valve opening direction pressure receiving surface 55 is provided with the valve rod engaging hole 3.
5, the discharge pressure Pd of the compressor is applied to the pressure-receiving surface 55 in the valve opening direction from the discharge pressure passage 36 as a correction pressure. The discharge pressure passage 36 is an intermediate portion of the valve housing 31 and is a passage for guiding the discharge pressure Pd of the compressor as a correction pressure to the valve receiving direction pressure receiving surface 55.

A compression coil spring, which is much weaker than the compression coil spring 54 in the spring box 47, is provided between the pressure receiving surface 55 of the valve rod 42 in the valve opening direction and the end surface of the large diameter portion 35a of the valve rod engagement hole 35. A correction spring 56 is provided.

Further, an internal communication hole 57 is formed in the valve housing 31 for connecting the suction port side passage 33 of the communication passage 34 to the diaphragm chamber 49. Although the discharge pressure passage 36 exists between the suction port side passage 33 and the diaphragm chamber 49, the internal communication hole 57 is located at a position deviated from the discharge pressure passage 36, and the internal communication hole 57 communicates with the discharge pressure passage 36. It extends across the discharge pressure passage 36 without having to do so.

Thus, there is no problem even if the discharge pressure passage 36 exists between the suction port side passage 33 and the diaphragm chamber 49, and a passage for guiding the intake pressure to the diaphragm chamber 49 is provided outside the valve housing 31. No special provision is required.

The control valve 30 having the above-described configuration is inserted and fixed in the control valve receiving hole 23 of the compressor housing 2, and the crank chamber side passage 32 is connected to the crank chamber pressure passage 24 opening at the bottom of the control valve receiving hole 23. The suction port side passage 33 and the annular circumferential groove 37 communicate with the suction port 14 through the suction pressure passage 25, and the discharge pressure passage 36 and the annular circumferential groove 38 communicate with the discharge port 15 through the discharge pressure passage 26. Communicating.

The crank chamber pressure passage 24, the suction pressure passage 25, and the discharge pressure passage 26 are pressure passages formed inside the compressor housing 2.

O-rings 59 and 60 are attached to both sides of the annular peripheral groove 37 of the control valve 30, and the O-ring 59 blocks communication between the crank chamber side passage 32 and the suction port side passage 33 outside the valve. The O-ring 60 blocks communication between the suction port side passage 33 and the discharge pressure passage 36. Further, an O-ring 6 is provided between the upper lid 44 and the compressor housing 2.
1 is attached, and the O-ring 61 performs airtight shutoff between the discharge pressure passage 36 and the outside.

Next, the operation of the capacity control valve 30 having the above configuration will be described.

When the suction pressure Ps of the compressor 1 is
4 to the annular circumferential groove 37 and the suction port side passage 33 via the suction pressure passage 25, and further enters the diaphragm chamber 49 through the internal communication hole 57, thereby driving the ball valve body 40 in the valve opening direction.

Assuming that the discharge pressure Pd acting as a correction pressure on the valve direction pressure receiving surface 55 is constant, the ball valve body 40 closes due to the valve opening force due to the suction pressure Ps acting on the diaphragm 45 and the spring force of the compression coil spring 54. It is driven to open and close by the balance relationship with the valve force. Here, the spring force of the correction spring 56 is negligible because the spring force of the correction spring 56 is weak and constant and has little effect on the control valve characteristics.

Accordingly, the suction pressure Ps is reduced by the compression coil spring 5
The control valve set pressure (reference set pressure P
ss) or less, the diaphragm 45 is displaced upward in FIGS. 1 and 2 by the spring force of the compression coil spring 54, and the ball valve body 40 is closed via the valve rod 42 and moved to the valve seat 41. Sit down and close the valve. The valve closing movement of the ball valve body 40 is stably performed without causing side-shift or the like in a state where the valve rod 42 and the valve rod engaging hole 35 are fitted and guided.

Thus, the supply of the suction pressure Ps to the crank chamber 3 is stopped, the crank chamber pressure Pc increases, and the compressor 1 enters the unload operation state.

On the other hand, when the suction pressure Ps becomes equal to or higher than the control valve set pressure (reference set pressure Pss), the diaphragm 45 is moved against the spring force of the compression coil spring 54 as shown in FIGS.
, The ball valve element 40 moves to open via the valve rod 42, separates from the valve seat 41, and opens. The valve opening movement of the ball valve body 40 is also caused by the valve rod 42 and the valve rod engagement hole 35.
In the state of the fitting guide, stable operation is performed without occurrence of lateral displacement or the like.

As a result, the suction pressure Ps is supplied to the crank chamber 3, the crank chamber pressure Pc becomes equal to the suction pressure Ps, and the compressor 1 enters a full load operation state.

As described above, when the discharge pressure Pd acting as the correction pressure on the valve-opening direction pressure receiving surface 55 is kept constant, that is, when the high pressure correction is not performed, the compressor 1 moves to FIG. As shown by the broken line, the capacity control operation is performed in which the suction pressure Ps is constant at the reference set pressure Pss.

The discharge pressure Pd acts as a correction pressure on the pressure receiving surface 55 in the valve opening direction of the valve rod 42, and the sectional area of the large diameter portion 42a is
h ₁ , assuming that the cross-sectional area of the small diameter portion 42 b is Ah ₂ , (Ah
₁₋ Ah ₂ ) · (Pd−Ps).

Since the intake pressure Ps can be regarded as substantially constant, the differential pressure ΔP (≒ Pd−Ps), that is, the valve opening force (Ah ₁ −Ah ₂ ) correlated with the discharge pressure Pd.
-Pd is added to the ball valve body 40.

The valve rod 42 is provided with a pressure-receiving surface 55 in the valve-opening direction, and correlates with the discharge pressure Pd (Ah ₁ -Ah ₂ ) · Pd.
The valve opening force acts on the ball valve body 40, the reference set pressure P in a balanced state at the reference discharge pressure Pds
If ss is set by adjusting the spring force of the adjustment spring 42, the suction pressure Ps required for opening the valve increases due to a decrease in the discharge pressure Pd (discharge pressure Pd <reference discharge pressure Pds),
Increase in discharge pressure Pd (discharge pressure Pd> reference discharge pressure Pd
Due to s), the suction pressure Ps required for opening the valve is reduced.

That is, when the discharge pressure Pd decreases to Pd ', the valve opening force becomes (Ah ₁ -Ah ₂ ) ・ (Pd-Pd').
The valve opening pressure becomes (Ah ₁ -Ah) based on the ratio between the valve opening force and the effective pressure receiving area Ad of the diaphragm 36.
₂ ) A pressure characteristic that increases in accordance with (Pd-Pd ') / Ad is obtained.

This is expressed by the following equation, and the desired high pressure influence characteristic can be obtained by selecting the difference in the outer diameter of the valve stem 42 that determines the pressure receiving area (Ah ₁ -Ah ₂ ). _{Ps = Pss- (Ah 1 -Ah 2} ) · (Pd-Pds)
/ Ad

Thus, as shown by the solid line in FIG. 3, the suction pressure Ps is proportional to the increase of the discharge pressure Pd.
Is obtained, and the control characteristics of the displacement control compressor can be matched by the discharge pressure Pd correlated with the system load characteristics.

This means that in the refrigerant circuit system, the evaporating load and the condensing load are in a proportional relationship, the evaporating load is proportional to the refrigerant circulation amount, and the pressure loss in the evaporator is proportional to the refrigerant circulation amount. As a result, the capacity of the compressor can be controlled effectively as an efficient energy saving system.

[0052]

As can be understood from the above description, the control valve for a variable displacement compressor according to the first aspect of the present invention has a communication passage communicating the suction port of the compressor with the crank chamber. A valve housing, a valve body provided in the valve housing for opening and closing the communication passage, and slidably fitted in a valve rod engaging hole formed in the valve housing, one end of which is connected to the valve body. A valve stem, a spring for urging the valve element in a valve closing direction, and a valve fixed to the valve housing and connected to the other end of the valve stem, and the valve is actuated by a suction pressure of the compressor applied to a diaphragm chamber. A diaphragm device for driving the valve body in the valve opening direction via a rod, wherein a valve opening direction pressure receiving surface is formed in an intermediate portion of the valve rod, and an intermediate portion of the valve housing has the valve opening direction. The discharge pressure of the compressor is applied to the pressure receiving surface by the valve opening method of the valve body. A discharge pressure passage for guiding the pressure as a correction pressure is formed in the valve housing, and an internal communication hole is formed in the valve housing for connecting the suction port side of the compressor to the diaphragm chamber. It was taken.

For this reason, a valve-opening direction pressure receiving surface is formed at an intermediate portion of the valve rod, and the discharge pressure of the compressor is applied to the valve-opening direction pressure receiving surface from a discharge pressure passage formed at an intermediate portion of the valve housing. A high pressure influence characteristic (discharge pressure influence characteristic) corresponding to the compressor discharge pressure correlated with the system load characteristic is set. In this case, an arbitrary high pressure influence characteristic can be obtained by setting the area of the pressure receiving surface in the valve opening direction.

The valve body is connected to the valve stem, and the valve stem is slidably fitted in the valve housing valve stem engaging hole, so that the valve body does not move sideways with respect to the valve housing. In addition, the structure can be simplified, and the opening and closing operation of the valve can be reliably performed.

Further, the suction pressure of the compressor is applied to the diaphragm chamber from the compressor suction port side of the communication passage by the internal communication hole formed inside the valve housing. The passage structure, especially the passage structure formed in the compressor housing, does not become complicated even if the passage is on the opposite side of the communication passage.

As described above, the structure is simplified, the opening / closing operation of the valve body is more reliable, the number of parts and the number of assembling steps are not increased, and as a compressor housing built-in type, A control valve for a variable displacement compressor can be obtained which does not complicate the passage structure and is excellent in the degree of freedom of the arrangement position in the compressor housing.

According to the control valve for a variable displacement compressor according to the second aspect of the present invention, the pressure receiving surface in the valve opening direction is
The valve stem portion of the valve stem, which is formed in a portion of the valve stem that is exposed to the discharge pressure passage, has a larger-diameter stepped portion on the valve-opening side than on the valve-closing side of the valve body. .

For this reason, the high pressure influence characteristic obtained by setting the area of the pressure receiving surface in the valve opening direction formed at the intermediate portion of the valve stem is
A high degree of freedom can be set by the valve stem diameter difference that forms a step in the middle of the valve stem.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a variable displacement compressor incorporating a control valve according to the present invention.

FIG. 2 is a sectional view showing one embodiment of a control valve for a variable displacement compressor according to the present invention.

FIG. 3 is a graph showing discharge pressure-suction pressure characteristics of a control valve for a variable displacement compressor according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Swash plate type variable capacity compressor 2 Compressor housing 3 Crank chamber 4 Cylinder chamber 5 Piston 7 Drive shaft 9 Wobble plate 14 Suction port 15 Discharge port 23 Control valve receiving hole 24 Crank chamber pressure passage 25 Suction pressure passage 26 Discharge pressure passage REFERENCE SIGNS LIST 30 control valve 31 valve housing 32 crank chamber side passage 33 suction port side passage 34 communication passage 35 valve rod engaging hole 36 discharge pressure passage 39 valve chamber 40 ball valve element 41 valve seat part 42 valve rod 43 diaphragm device 45 diaphragm 49 diaphragm Chamber 50 Sealed chamber 54 Compression coil spring 55 Valve-opening direction pressure receiving surface 56 Correction spring 57 Internal communication hole

Continued on the front page F term (reference) 3H045 AA04 AA13 AA27 BA19 CA01 CA02 CA03 DA25 EA33 3H076 AA06 BB40 BB41 CC41 CC85 CC92 CC93

Claims (2)

[Claims] A valve housing having a communication passage communicating the suction port of the compressor with the crank chamber; a valve body provided in the valve housing to open and close the communication passage; and a valve body formed in the valve housing. A valve rod slidably fitted in a valve rod engaging hole, one end of which is connected to the valve element; a spring for urging the valve element in a valve closing direction; and the valve fixed to the valve housing. A diaphragm device connected to the other end of the rod and driving the valve body in the valve opening direction via the valve rod by suction pressure of the compressor exerted on a diaphragm chamber; A valve direction pressure receiving surface is formed, and a discharge pressure passage for guiding the discharge pressure of the compressor to the valve opening direction pressure receiving surface as a correction pressure in the valve opening direction of the valve body is formed in an intermediate portion of the valve housing. The communication passage is provided inside the valve housing. Of the inner communication hole suction port side of the compressor and said diaphragm chamber is connected in communication is formed, the variable displacement compressor control valve, characterized in that. 2. The valve-opening direction pressure-receiving surface has a larger diameter on the valve-opening side than on the valve-closing side of the valve body, which is formed on a valve stem portion of the valve stem that is exposed to the discharge pressure passage. The control valve for a variable displacement compressor according to claim 1, wherein the control valve is constituted by an end face of the stepped portion.