JP3080280B2 - Control valve for variable displacement compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a variable displacement compressor for vehicle air conditioning provided with a suction chamber, a discharge chamber and a crank chamber, and controls the pressure in the crank chamber to control the discharge capacity of the variable displacement compressor. A variable control valve.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 58-158382
The variable displacement type compressor described in Japanese Patent Application Laid-Open No. H10-209,043 is known. In this variable displacement compressor, a cylinder block having a plurality of bores parallel to the axis is closed by a front housing and a rear housing, and a crank chamber is formed between the cylinder block and the front housing. A drive shaft is rotatably supported in the crank chamber by a front housing and a cylinder block, and a swash plate is slidably moored to the drive shaft. A rocking plate is moored to the swash plate in a rotation-restricted state, and each piston is moored via a rod to the rocking plate, and each piston is accommodated in each bore so as to be able to reciprocate. Further, a suction chamber and a discharge chamber are formed in the rear housing, and a valve plate and the like are interposed between the suction chamber and the discharge chamber and each bore.
Further, a control valve shown in FIG. 5 is provided in the rear housing. This control valve is provided with a bellows 91 which is displaced by detecting the compressor inlet pressure out of the suction pressure Ps, and the displacement of the bellows 91 causes a communication passage between the discharge chamber and the crank chamber. A valve mechanism 94 is provided for controlling the opening of the valve 92 and the opening of the communication passage 93 between the crank chamber and the suction chamber.

A variable displacement compressor disclosed in Japanese Utility Model Laid-Open Publication No. Sho 62-31782 discloses a control valve employing an evaporator outlet pressure as a suction pressure detected by a bellows. In these variable displacement compressors, if the compressor inlet pressure or the evaporator outlet pressure exceeds a predetermined pressure as the ambient temperature rises, for example, in the control valve shown in FIG. The mechanism 94 is operated to open the communication passage 93 between the crank chamber and the suction chamber, while closing the communication passage 92 between the discharge chamber and the crank chamber. As a result, the crank chamber pressure Pc is led to the suction pressure Ps side, so that the crank chamber pressure Pc decreases, the back pressure acting on the piston decreases, and the tilt angle of the swing plate increases, thereby increasing the stroke of the piston. This increases the discharge capacity.

On the other hand, when the compressor inlet pressure or the evaporator outlet pressure decreases to a predetermined pressure due to a decrease in the ambient temperature,
In this control valve, the valve mechanism 9
4 is actuated to provide a communication passage 9 between the crank chamber and the suction chamber.
3, while the communication passage 92 between the discharge chamber and the crank chamber is opened. Thereby, the crank chamber pressure Pc
Side, the discharge pressure Pd is introduced to the crank chamber pressure P
c rises, the back pressure acting on the piston rises, and the stroke of the piston is reduced due to the reduction of the tilt angle of the swing plate, and the discharge capacity is reduced.

Thus, in these variable displacement compressors, the ambient temperature and the suction pressure Ps (compressor inlet pressure Psc
And the evaporator outlet pressure Pse).

[0006]

However, in the variable displacement compressor using each of the above-described control valves, as shown in FIG. 6, the pressure receiving area of the bellows 91: S ₁ , the bellows 91
Displacement set pressure: P ₀ , communication passage 92 in valve mechanism 94
Passing area: S ₂ , suction pressure: Ps, discharge pressure: Pd,
When the crank chamber pressure is Pc, the force S ₁ P ₀ for displacing the bellows 91 is represented by the following _equation : S ₁ P ₀ = S ₁ Ps + S ₂ Pd−S ₂ Pc (1)

From equation (1), it can be seen that S ₁ P ₀ changes according to Pd which greatly changes, and the degree of opening of the communication passage 92 is determined by the force S ₂ Pd in the contraction direction. For this reason,
In this control valve, when the ambient temperature is relatively high (region A in FIG. 7), the opening degree of the communication passage 92 is balanced with the force by the large Pd, so that a large pressure loss ΔP is added to the compressor inlet pressure Psc. In addition, the evaporator outlet pressure Pse is kept almost constant at a low value, and in the refrigeration cycle of the air conditioner, an increase in enthalpy is ensured in a region where the absolute pressure is low, so that sufficient cooling capacity can be ensured, but the ambient temperature is relatively low. In the case (region B in FIG. 7), Pd is greatly reduced and the opening of the communication passage 92 is expanded more than necessary, so that the discharge capacity is excessively reduced and the compressor inlet pressure Psc
In addition, the evaporator outlet pressure Pse rises, and the enthalpy must be increased in a region where the absolute pressure is high in the refrigeration cycle, resulting in insufficient cooling capacity.

In particular, the ambient temperature and the suction pressure Ps shown in FIG.
Is merely set to adopt the outside air as the ambient temperature and to avoid the range F in which frost occurs in the evaporator. Here, in a Japanese car, etc., which can be switched between "outside air" and "inside air" so that the bad smell due to "outside air" does not need to be introduced into the cabin during traffic jams,
When the circulation is performed, the relationship between the ambient temperature and the suction pressure Ps partially overlaps with the range C where clouding occurs in the window of the vehicle. That is, when the `` outside air '' circulates `` inside air '' at low temperature, for example, when the auto air conditioner is operated in winter and the indoor air is quickly heated by `` inside air '' and dehumidification is desired, Therefore, the cooling capacity is insufficient in the region B of FIG. For this reason, suitable dehumidification becomes difficult, and a cloud of a window of a vehicle occurs.

In order to solve this problem, the compressor inlet pressure Psc and the evaporator outlet pressure Psc in the region B shown in FIG.
It is also conceivable to set a small gradient of the absolute value of the straight line in the relationship between the ambient temperature and the suction pressure Ps so that se does not increase. In this case, Ps = −S ₂ Pd / S ₁ + S ₂ Pc / S ₁ + P ₀ (2) is obtained from the above equation (1), and (Pd, Ps Taking) coordinates, the slope of the straight line is found to be determined by -S ₂ / S _1. Here, if the inclination of the straight line is not reduced,
Increase the S _1, it requires reducing the S _2.

[0010] However, by increasing the S _1, together with the bellows 91 lacks mountability by producing an increase in the size of the control valve is enlarged, the response of the control valve is impaired easily. Furthermore, by reducing the S _2, since the communication passage 92 is reduced, the flow rate of the refrigerant gas from the discharge chamber to the crank chamber is decreased, is also the response of the control valve is impaired easily.

The present invention ensures a sufficient cooling capacity when the ambient temperature is relatively high without impairing the mountability and responsiveness of the control valve, and provides a sufficient cooling capacity even when the ambient temperature is relatively low. Being able to secure is an issue to be solved.

[0012]

SUMMARY OF THE INVENTION A control valve for a variable displacement compressor according to the present invention is used in a variable displacement compressor for a vehicle air conditioner having a suction chamber, a discharge chamber and a crank chamber in order to solve the above problems. A pressure-sensitive mechanism that detects and changes the suction pressure,
A valve mechanism for controlling at least an opening degree of a communication passage between the discharge chamber and the crank chamber by a displacement of the pressure-sensitive mechanism, and controlling a crank chamber pressure to discharge the variable displacement compressor. In a control valve for a variable displacement compressor that varies the displacement,
A correction mechanism for correcting the opening degree control of the communication path between the discharge chamber and the crank chamber by the valve mechanism by adjusting the influence of the discharge pressure by opposing the discharge pressure and the crank chamber pressure, The present invention employs a novel configuration including a correction stop mechanism that stops the operation of the correction mechanism when the discharge pressure exceeds a set pressure.

[0013]

In the variable displacement compressor using the control valve of the present invention, if the suction pressure exceeds a predetermined pressure due to the rise in the ambient temperature, the pressure-sensitive mechanism in the control valve will oppose the set force. And the valve mechanism is actuated to shut off the communication path between the discharge chamber and the crank chamber. As a result, the discharge capacity is increased because the crank chamber pressure decreases.

Conversely, when the suction pressure decreases to a predetermined pressure due to a decrease in the ambient temperature, the pressure-sensitive mechanism is displaced by the set force in the control valve, and the valve mechanism is actuated. The communication path between them is opened. Thereby, the discharge capacity is reduced because the crank chamber pressure increases. During these times, if the discharge pressure exceeds the set pressure and the operation of the correction mechanism is stopped by the correction stop mechanism, the correction mechanism does not correct the control of the valve mechanism. Thereby, the opening degree of the communication passage is
As in the conventional case, it is determined by receiving the force in the normal contraction direction due to the discharge pressure of the valve mechanism. Therefore, in this control valve,
When the ambient temperature is relatively high, the relationship between the ambient temperature and the suction pressure can be established under a constant gradient set so that sufficient cooling capacity can be ensured by the operation of the valve mechanism.

On the other hand, during these times, if the discharge pressure does not exceed the set pressure and the operation of the correction mechanism is not stopped by the correction stop mechanism, the correction mechanism operates the valve mechanism by opposing the discharge pressure and the crank chamber pressure. Correct control. This allows
The opening degree of the communication passage is determined by receiving not only the force in the normal contraction direction due to the discharge pressure of the valve mechanism but also the force in the enlargement direction due to the discharge pressure of the correction mechanism. Therefore, in this control valve,
The inclination of the absolute value of the straight line in the relationship between the ambient temperature and the suction pressure can be bent and reduced.

If the gradient of the absolute value of the straight line in the relationship between the ambient temperature and the suction pressure is reduced in this manner, this control valve can control the discharge pressure even if the discharge pressure is greatly reduced when the ambient temperature is relatively low. Since the influence does not lead to an unnecessary expansion of the communication path and the discharge capacity is not excessively reduced, the increase in the suction pressure is suppressed and the cooling capacity is secured. Further, in this control valve, the relationship between the ambient temperature and the suction pressure does not overlap with the range in which the window of the vehicle becomes cloudy. For this reason, even if the "outside air" is at a low temperature, sufficient cooling capacity is still ensured, and suitable dehumidification is possible, so that clouding does not occur in the window of the vehicle.

In this control valve, the pressure sensing mechanism is not enlarged while the pressure receiving area of the pressure sensing mechanism is not increased and the passage area of the communication passage in the valve mechanism is not reduced while exhibiting such effects. And the flow rate of the refrigerant gas is not reduced.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. First, the control valve 3 of the embodiment shown in FIG.
A description will be given of a swinging swash plate type compressor for vehicle air-conditioning using 0. In this swinging swash plate type compressor, as shown in FIG. 2, a cylinder block 1 having a plurality of bores 1a parallel to an axis is closed by a front housing 2 and a rear housing 4. 2, a crank chamber 5 is formed. One end of the crankcase 5 extends from the front housing 2 and is driven between the front housing 2 and the front housing 2 via a shaft sealing device 2a and a radial bearing 2b and between the crankcase 5 and the cylinder block 1 via a radial bearing 1b. The shaft 6 is rotatably supported. The rotor 7 is fixed to the drive shaft 6 via a thrust bearing 2c between the drive shaft 6 and the front housing 2, and a sleeve 19 is inserted slidably in the axial direction.

The pin 8a of the swash plate 8 is inserted into the long hole 7b of the rotor 7.
The swash plate 8 is pivotally supported by pivot shafts 19 a protruding from both sides of the sleeve 19. The swash plate 8 has a thrust bearing 9 and a plain bearing 1.
0, a race 11 and a thrust washer 12, a rocking plate 13 is moored, and a part of the rocking plate 13
The rotation is regulated by the guide rod 16 extended inside. Each piston 15 is moored to the swing plate 13 via a rod 14, and each piston 15 is accommodated in each bore 1a so as to be able to reciprocate.

The rear housing 4 has a suction chamber 17 on the outer circumference and a discharge chamber 18 on the inner circumference. A suction valve 3 is provided between the suction chamber 17 and the discharge chamber 18 and each bore 1a.
a, the valve plate 3b and the discharge valve 3c are interposed. Valve plate 3
b and the discharge valve 3c have a suction chamber 1 opened and closed by the suction valve 3a.
7 and each bore 1a, a suction port is provided therethrough, and each of the bores 1a and 3b is opened and closed by a discharge valve 3c.
A discharge port is provided between a and the discharge chamber 18.
A retainer 3d is fixed in the discharge chamber 18 so as to face the valve portion of the discharge valve 3c, and the control valve 30 of the present embodiment shown in FIG. Is equipped.

Further, as shown in FIG. 2, the cylinder block 1 and the rear housing 4 communicate with the air supply passage 20 for connecting the crank chamber 5 and the control valve 30, and the crank chamber 5 and the suction chamber 17. A bleed passage 21 having an orifice 21a in the middle is provided therethrough. Also, the rear housing 4
Has a communication passage 22 connecting the suction chamber 17 and the control valve 30.
And a communication passage 23 connecting the discharge chamber 18 and the control valve 30 is provided therethrough.

Next, the control valve 30 of the embodiment shown in FIG. 1 will be described. In the control valve 30, a valve body 31 and a cylindrical body 32
A diaphragm 33 as a pressure-sensitive mechanism is sandwiched by the sandwiching member 34 with a predetermined pressure receiving area S ₁ (see FIG. 3). A screw member 35 is screwed into the cylinder 32, and the cylinder 32, the screw member 35, and the diaphragm 33 are screwed.
An atmosphere chamber 50 is formed by one side of the holding member 34. The air hole 32a penetrating through the cylinder 32 is communicated with the atmosphere chamber 50 by backlash with the screw member 35, whereby the atmospheric pressure P ₀ (see FIG. 3) is introduced into the atmosphere chamber 50. In the atmosphere chamber 50, a spring 36 having a predetermined pressing force is interposed between the screw member 35 and the presser foot 37 in section, and a ball 38, a ring presser 39, and a plate are provided at the other end of the presser 37. Diaphragm 33 through 40
Is located.

At the upper end of the valve body 31, a suction pressure chamber 51 is formed between the diaphragm 33 and the other side of the holding member 34. The suction pressure chamber 51 is connected to the communication passage 22a of the compressor by a communication passage 51a. Thus, the suction pressure Ps (see FIG. 3) is introduced into the suction pressure chamber 51. The suction pressure chamber 51 is provided with a Π-shaped presser 41 in contact with the diaphragm 33, and a spring 42 having a predetermined pressing force is interposed between the presser 41 and the bottom surface of the suction pressure chamber 51. An upper end of a rod 43 slidable in the valve body 31 is fixed to the presser foot 41, and a ball 45 is fixed to a lower end of the rod 43.

The discharge pressure chamber 5 is provided at the lower end of the valve body 31.
2 are formed, and a valve seat is formed in the discharge pressure chamber 52 so that the ball 45 can contact and separate therefrom. This discharge pressure chamber 52
Is communicated with the communication passage 23 of the compressor by a communication passage 52a, so that a discharge pressure Pd (see FIG.
See). The discharge pressure chamber 52 is provided with a C-shaped presser 46 in contact with the ball 45, and a spring 47 having a predetermined pressing force is interposed between the presser 46 and the bottom surface of the discharge pressure chamber 52.

Further, a communication passage 20a communicating with the air supply passage 20 of the compressor is formed in the valve body 31, and the communication passage 20a is formed in a sliding region of the rod 43 in the sliding area.
b communicates with the discharge pressure chamber 52. The passage area of the communication passage 52b is set to S ₂ (see FIG. 3). Thus, the valve mechanism of the control valve 30 is configured.

The most characteristic configuration of the control valve 30 is a correction valve.
It has a mechanism. That is, the rod 43
A predetermined pressure receiving surface between the presser foot 41 and the ball 45
Product S _Three(See FIG. 3)
The control piston 44 is connected to the valve body 31 by the diaphragm 3.
A correction chamber 53 slidable by the displacement of 3 is formed.
You. Between the presser foot 41 side of the correction chamber 53 and the discharge pressure chamber 52
Is formed with a communication path 53a, and a ball 45 of the correction chamber 53 is formed.
A communication passage 53b is provided between the side of the rod 43 and the communication passage 20a.
Are formed in the sliding area.

The second characteristic of the control valve 30 is that a switching valve as a correction stop mechanism is provided in the communication passage 53a. That is, in the middle of the communication passage 53a, a spring 48 having a predetermined pressing force is held on the correction chamber 53 side, and a valve body 49 capable of shutting off the correction chamber 53 side is held on the spring 48. The swinging swash plate type compressor incorporating the control valve 30 configured as described above is incorporated in a refrigeration circuit together with a condenser, an expansion valve, an evaporator, and the like (not shown), and is shown in FIG. 2 by the driving force of the vehicle engine. Drive shaft 6
Is driven and used.

That is, the rotation of the drive shaft 6 causes the rotor 7 to rotate.
, The swash plate 8 rotates at a predetermined inclination angle, and the oscillating plate 13 oscillates at the same inclination angle with the rotation restricted. As a result, the piston 15 reciprocates in the bore 1a with a predetermined stroke, so that the refrigerant gas is drawn into the bore 1a from the suction chamber 17 connected to the evaporator to increase the entropy of the refrigerant gas, and then the bore 1a Compress the refrigerant gas in the
The refrigerant gas is discharged from inside a into a discharge chamber 18 connected to a condenser.

Here, the discharge pressure Pd exceeds the set pressure,
In the control valve 30 shown in FIG. 1, if the valve element 49 blocks the communication chamber 53 side of the communication passage 53a against the spring 48,
The correction mechanism does not correct the control of the valve mechanism. Therefore, when the suction pressure Ps, which is the compressor inlet pressure Psc, exceeds the predetermined pressure with the rise in the ambient temperature, the atmospheric pressure P ₀ and the spring 3
Diaphragm 33 against set force by 6, 42, 47
Is displaced upward. As a result, the ball 45 is seated on the valve seat of the discharge pressure chamber 52 via the rod 43, and the communication path 52
In order to shut off b, the discharge chamber 18 and the crank chamber 5 shown in FIG. 2 are shut off. Since the crank chamber 5 and the suction chamber 17 are communicated with each other by the bleed passage 21 having an orifice 21a in the middle, the refrigerant in the crank chamber 5 is discharged to the suction chamber 17 by a predetermined amount. Thus, the supply of the high-pressure refrigerant gas from the discharge chamber 18 into the crank chamber 5 is cut off, so that the crank chamber pressure Pc decreases, the back pressure acting on the piston 15 decreases, and the tilt angle of the rocking plate 13 increases. By piston 1
The stroke of No. 5 is increased, and the discharge capacity is expanded.

While the correction mechanism has not yet corrected the control of the valve mechanism, on the contrary, when the suction pressure Ps has decreased to a predetermined pressure due to a decrease in the ambient temperature, the diaphragm 33 is displaced downward by the same set force. I do. Thereby, the rod 4
The ball 45 separates from the valve seat of the discharge pressure chamber 52 via 3 and opens the communication passage 52b. For this reason, the discharge pressure chamber 5
The high-pressure refrigerant gas in 2 is introduced into the crank chamber 5 through the communication passages 52b and 20a and the air supply passage 20. Thus,
The crank chamber pressure Pc increases, the back pressure acting on the piston 15 increases, and the stroke of the piston 15 decreases due to the reduction of the tilt angle of the swinging plate 13, thereby reducing the discharge capacity.

During this time, the control valve 30 applies a force S ₁ P ₀ to displace the diaphragm 33 as shown in FIG.
S ₁ P ₀ = S ₁ Ps + S ₂ Pd−S ₂ Pc (3) This equation (3) is the same as the above equation (1), and the opening degree of the communication passage 52b is determined by receiving the force S ₂ Pd in the normal contraction direction for pressing the ball 45 upward, as in the conventional case. You can see that

[0032] than addition _{(3), Ps = -S 2 Pd / S} 1 + S 2 Pc / S 1 + P 0 ... (4) is obtained. This equation (4) is the same as the above equation (2). If the coordinates of (Pd, Ps) are taken, the slope of the straight line is −S ₂
/ S ₁ it can be seen that is determined by the. As a result, in the control valve 30, when the ambient temperature is relatively high (region A in FIG. 4), as shown in FIG. 4, a large pressure loss ΔP is added to the compressor inlet pressure Psc by the operation of the valve mechanism. In addition, the evaporator outlet pressure Pse is kept almost constant at a low value,
The relationship between the ambient temperature and the suction pressure is established under a constant gradient set so as to ensure sufficient cooling capacity.

On the other hand, the discharge pressure Pd becomes lower than the set pressure, and in the control valve 30 shown in FIG.
If the correction chamber 53 side of the communication path 53a is opened by 8, the correction mechanism corrects the control of the valve mechanism. That is, the refrigerant gas in the discharge pressure chamber 52 is introduced into the correction chamber 53 via the communication path 53a. For this reason, the discharge pressure Pd acts on the upper end of the control piston 44, and opposes the crank chamber pressure Pc that is introduced from the communication passage 53b and acts on the lower end of the control piston 44.

Here, in this control valve 30, as shown in FIG. 3, the force S ₁ P ₀ for displacing the diaphragm 33 is S ₁ P ₀ = S ₁ Ps + Pd (S ₂ −S ₃ ) −Pc (S ₂ −S ₃ ) (5) Comparing Equation (5) with Equations (1) and (3) above, it can be seen that S ₂ −S ₃ affects the change in S ₁ P ₀ . The opening degree of the communication passage 52b is determined by the force S ₂ Pd in the normal contraction direction for pressing the ball 45 upward by the discharge pressure Pd and the force S _{3 in the} enlargement direction for pressing the control piston 44 downward by the discharge pressure Pd. It can be seen that Pd is also determined.

From equation (5), Ps = − (S_Two-S_Three) Pd / S₁+ (S_Two-S_Three) Pc / S₁+ P₀ ... Formula (6) is obtained. This equation (6) and the above equations (2) and (4)
And-(S _Two-S_Three) / S₁Is (Pd, P
s) The slope of the coordinate straight line is determined, and-(S_Two−
S_Three) / S₁Is -S in equations (2) and (4)_Two/ S₁Yo
R_ThreeIt turns out that it is only small.

[0036] Thereby, in the control valve 30, by setting the S _3, as shown in FIG. 4, region A determining the operation of the correction mechanism, as a boundary the boundary B, the ambient temperature and the suction pressure Ps (compression Inlet pressure Psc and evaporator outlet pressure Ps
The inclination of the absolute value of the straight line in the relationship with e) can be bent and reduced. Therefore, this control valve 3
In the case of 0, even when the discharge pressure Pd is greatly reduced when the ambient temperature is relatively low (region B in FIG. 4), the discharge pressure Pd
Does not lead to an unnecessary expansion of the communication passage 52b, and the discharge capacity is not excessively reduced. Therefore, an increase in the suction pressure is suppressed and the cooling capacity is secured.

Further, in the control valve 30, the relationship between the ambient temperature and the suction pressure Ps shown in FIG. 4 does not overlap with the range C where clouding occurs in the window of the vehicle. For this reason, even if the "outside air" is at a low temperature, sufficient cooling capacity is still ensured, and suitable dehumidification is possible, so that clouding does not occur in the window of the vehicle.
And with this control valve 30, while exhibiting such an effect,
Or by increasing the pressure receiving area S ₁ of the diaphragm 33, because no or to reduce the passage area S ₂ of the communication passage 52 b, never the diaphragm 33 is expanded, without also decreasing the flow rate of the refrigerant gas.

Therefore, in the swinging swash plate type compressor using the control valve 30, sufficient cooling capacity is secured when the ambient temperature is relatively high, and sufficient cooling capacity is secured even when the ambient temperature is relatively low. Can be secured. For this reason, particularly in a Japanese car or the like which is capable of switching between “outside air” and “inside air”, for example, even when the auto air conditioner is operated in winter and the room is quickly heated by “inside air”, it is suitable. Dehumidification becomes possible, and clouding does not occur in the windows of vehicles.

In addition, in the swash plate type compressor using the control valve 30, the control valve 3 is provided while exhibiting the above-described excellent effects.
0 does not impair the mountability and responsiveness. In the above embodiment, if S ₃ = S ₂ , − (S ₂ −S ₃ ) / S ₁ = while the correction mechanism is operating in the area B.
0, and equation (6) is parallel to the Pd axis at (Pd, Ps) coordinates. In this case, the correction mechanism corrects the control of the valve mechanism so as to increase the opening degree of the communication passage 52b, and the opening degree of the communication passage 52b is increased in the expansion direction together with the normal reduction force S ₂ Pd by the discharge pressure Pd. It is determined under the balance with S ₃ Pd. That is, Pd that greatly changes is ignored, and the opening degree of the communication passage 92 is determined substantially only by the suction pressure Ps.

In the above embodiment, if S ₃ > S ₂ , while the correction mechanism is operating in the region B, −
(S ₂ −S ₃ ) / S ₁ = positive, and the expression (6) becomes (Pd,
Ps) has a positive slope in coordinates. In this case, the correction mechanism
The control of the valve mechanism is corrected so as to reduce the opening degree of the communication path 52b, and the opening degree of the communication path 52b is such that the force S ₃ Pd in the enlargement direction is larger than the normal reduction force S ₂ Pd due to the discharge pressure Pd. Is determined.

In addition, in the above-described embodiment, an oscillating swash plate type compressor has been described as an example. However, a variable displacement type compressor for a vehicle air conditioner having a suction chamber, a discharge chamber, and a crank chamber may be oscillated. Other types of compressors, such as plateless reciprocating compressors, can also be employed. Further, in the above embodiment, the diaphragm is adopted as the pressure sensing mechanism, but it goes without saying that a bellows can be adopted.

Further, in the above-described embodiment, the valve mechanism for controlling only the opening degree of the communication passage between the discharge chamber and the crank chamber by the displacement of the pressure sensing mechanism has been described as an example. The present invention can also be embodied in a conventional valve mechanism that controls the opening degree of the communication passage between the crank chamber and the suction chamber. Further, in the above embodiment, the suction pressure Ps introduced into the suction pressure chamber 51 of the control valve 30 is set as the compressor inlet pressure P
Although the sc is adopted, the evaporator outlet pressure Pse may be adopted.

[0043]

As described above in detail, when the control valve of the present invention is used in a variable displacement compressor, when the ambient temperature is relatively high, sufficient cooling capacity is ensured while the ambient temperature is relatively low. Even in this case, sufficient cooling capacity can be secured. For this reason, particularly in a Japanese car or the like which is capable of switching between “outside air” and “inside air”, for example, even when the auto air conditioner is operated in winter and the room is quickly heated by “inside air”, it is suitable. Dehumidification becomes possible, and clouding does not occur in the windows of vehicles.

Moreover, in the variable displacement compressor using the control valve, the above-described excellent effects are exhibited, and the mountability and responsiveness of the control valve are not impaired.

[Brief description of the drawings]

FIG. 1 is a sectional view of a control valve according to an embodiment.

FIG. 2 is a sectional view of a swinging swash plate type compressor for vehicle air conditioning using a control valve according to an embodiment.

FIG. 3 is a schematic view of a control valve according to the embodiment.

FIG. 4 is a graph showing a relationship between an ambient temperature and a suction pressure in a swash plate type compressor for vehicle air conditioning using a control valve according to an embodiment.

FIG. 5 is a sectional view of a conventional control valve.

FIG. 6 is a schematic view of a conventional control valve.

FIG. 7 is a graph showing the relationship between ambient temperature and suction pressure in a conventional swash plate type compressor for vehicle air conditioning using a control valve.

[Explanation of symbols]

17 ... suction chamber 18 ... discharge chamber 5 ...
Crank chamber 33 ... Diaphragm (pressure sensing mechanism) 30 ... Control valve 43, 45 ... Valve mechanism (43 ... Rod, 45 ... Ball) 20,23,52a, 52b, 20a ... Communication passage between discharge chamber and crank chamber (20: air supply passage, 23, 52a,
52b, 20a ... communication path 44, 53, 53a, 53b, 53c ... correction mechanism (44
... Control piston, 53 ... Correction chamber, 53a, 53b ... Communication passage) 48, 49 ... Correction stop mechanism (switching valve) Pc ... Crank chamber pressure Ps ... Suction pressure Pd
…Discharge pressure

Claims (1)

(57) [Claims] 1. A pressure-sensitive mechanism used in a vehicle air-conditioning variable displacement compressor having a suction chamber, a discharge chamber, and a crank chamber, the pressure-sensitive mechanism detecting a suction pressure and displacing the pressure-sensitive mechanism. A variable displacement compressor comprising: a valve mechanism for controlling an opening degree of a communication passage between the discharge chamber and the crank chamber, wherein the variable displacement compressor varies a displacement of the variable displacement compressor by controlling crank chamber pressure. A control valve for controlling the opening degree of the communication passage between the discharge chamber and the crank chamber by the valve mechanism by adjusting the influence of the discharge pressure by opposing the discharge pressure and the crank chamber pressure. A control valve for a variable displacement compressor, comprising: a correction mechanism that performs a correction, and a correction stop mechanism that stops the operation of the correction mechanism when the discharge pressure exceeds a set pressure.