JP3082485B2 - Oscillating swash plate type variable displacement compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillating swash plate type variable displacement compressor mainly used for compressing refrigerant gas in a vehicle air conditioner.

[0002]

2. Description of the Related Art Conventionally, a swash plate of a swash plate type in which the discharge capacity is varied by changing the inclination angle of the swash plate by adjusting the pressure in a crank chamber in which the swash plate is housed. As a variable displacement compressor, for example, Japanese Patent Application Laid-Open No. 62-2947
There is one disclosed in Japanese Patent Publication No. 81.

In this type of compressor, the pressure in the crank chamber is formed by the pressure leaking from between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston, that is, the blow-by gas pressure. It becomes higher than the suction pressure. Further, when the load is high, that is, when the suction pressure becomes equal to or higher than a predetermined set value, the pressure control valve interposed in the bleed passage between the crank chamber and the suction chamber is opened, and the pressure in the crank chamber (blow-by gas) is increased. Escapes into the inhalation chamber. For this reason, the pressure in the crank chamber decreases, and accordingly, the inclination angle of the swash plate increases, the piston stroke increases, and the discharge capacity increases. On the other hand, when the heat load decreases (medium load state) and the suction pressure decreases, the degree of opening of the pressure control valve decreases with the decrease in the suction pressure, whereby the pressure in the crank chamber flows into the suction chamber. The amount to do is reduced. For this reason, the pressure in the crank chamber rises, and accordingly, the inclination angle of the swinging swash plate decreases, the stroke of the piston decreases, and the discharge capacity decreases. The discharge capacity changes due to such an operation.

[0004] On the other hand, if a certain amount of refrigerant continues to flow despite the low load state and the heat load is low, the suction pressure on the low pressure side becomes too low, and the evaporation temperature of the refrigerant drops, and the evaporator freezes. Resulting in.

In order to prevent freezing of the evaporator, Japanese Patent Laid-Open Publication No. Sho 62-294781 discloses a pressure control valve interposed in a bleed passage connecting a crank chamber and a suction chamber as follows. I have. That is, this pressure control valve is attached to one end of the first bellows that expands and contracts according to the suction pressure,
A valve body is provided to open the bleed passage when the suction pressure is equal to or higher than a predetermined set value and to close the bleed passage when the suction pressure is equal to or lower than a predetermined set value. The pressure control valve is interposed between a first movable body attached to the other end of the first bellows and the first movable body and the valve body, and moves the valve body toward a valve closing side. A first spring for pressing.
The pressure control valve is attached to one end of a second bellows that expands and contracts in accordance with the discharge pressure, has a pressure receiving portion that receives the discharge pressure, and has a second movable member that comes into contact with and separates from the first movable body.
A movable body; and a spring seat attached to the other end of the second bellows. Further, the pressure control valve is interposed between the spring seat and the second movable body, and when the discharge pressure is equal to or less than a predetermined set value, the second movable body and the first movable body resist the discharge pressure. A second spring is provided for pressing the valve body to the valve closing side via a body, a first spring, and a first bellows.

Therefore, in the above-mentioned variable displacement compressor,
When the discharge pressure falls below a predetermined set value and the evaporator enters the freezing range, the valve body is pressed more strongly in the valve closing direction by the second spring, and the valve closing pressure increases, whereby the crank chamber is increased. Is increased, the inclination angle of the swash plate becomes smaller, the discharge capacity decreases, and the amount of refrigerant passing through the evaporator decreases, so that the evaporator is prevented from freezing.

[0007]

However, in the above-mentioned conventional variable displacement compressor, the pressure control valve includes a first bellows, a second bellows, a first movable body, a second movable body, a first spring and a second bellows. Since it is constituted by a spring or the like, there has been a problem that the valve structure is extremely complicated, and manufacturing and assembling operations are troublesome.

In general, in a cooling system, the suction side of the compressor and the outlet side of the evaporator are connected by a suction pipe or the like, so that a pressure loss of fluid occurs in the suction pipe or the like. This pressure loss is as large as about 0.5 kg / cm ² when the flow rate is high (at high flow rate). On the other hand, when the flow rate is low, the pressure loss is 0.1 kg / cm ² or less. Then, the suction pressure of the compressor is set to a constant value, for example, 2 kg / cm ^2.
Even if it is set to G, the evaporator outlet pressure is 2 to 2 depending on the cooling load.
It changes to 2.5 kg / cm ² G. Therefore, at the time of high cooling load, the flow rate of the refrigerant gas increases, and the pressure loss in the suction pipe increases. Therefore, the pressure of the evaporator increases, the cooling capacity is insufficient, and the cooling feeling deteriorates. .

In order to solve the above problem, Japanese Patent Laid-Open No.
A variable capacity compressor disclosed in JP-A-142276 has been proposed. The compressor has a bleed passage that connects the crank chamber and the suction chamber, and a control device that controls communication between the crank chamber and the suction chamber via the bleed passage. The control device includes an on-off valve that detects the pressure of the suction chamber or the pressure of the crank chamber to open and close the bleed passage. Further, there is provided operating point control means for applying a load generated by the pressure of the discharge chamber to the on-off valve to move the on-off operating point of the on-off valve. Further, the operating point control means has a valve cylinder communicating with the discharge chamber, and an actuating rod slidably inserted into the valve cylinder. To transmit the applied load.

According to the above-mentioned conventional compressor, the bleed passage between the suction chamber and the crank chamber is opened and closed by the on-off valve in response to the fluctuation of the pressure. The operating point of the on-off valve varies depending on the discharge pressure by the operating point control means. As a result, the pressure in the crank chamber is adjusted according to the pressure in the discharge chamber, so that the above-described pressure loss in the suction pipe is eliminated, and appropriate cooling can be performed.

However, in the above-described conventional capacity control of the compressor, the blow-by gas is small at a low discharge pressure, and the crank chamber pressure does not easily increase. As a result, the suction pressure does not increase,
There is a problem that the above-mentioned evaporator cannot be prevented from freezing. Means for constantly leaking gas from the discharge chamber to the crank chamber via the throttle is also known, but on the contrary, there is a problem in that a large amount of gas leaks at high discharge and the performance is reduced.

If the two conventional capacity control devices described above are respectively incorporated, it is possible to prevent freezing of the evaporator under a low cooling load condition and to compensate for a pressure loss of a suction pipe under a high cooling load condition. It is possible to perform proper cooling,
The structure becomes extremely complicated and the manufacture and assembly are further complicated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to reduce the suction pressure when the discharge pressure becomes high to compensate for the pressure loss in the suction pipe from the evaporator to the compressor. The pressure of the evaporator can be kept almost constant, the evaporator can be reliably prevented from freezing in the low discharge pressure region, and the structure of the pressure control valve is simplified, thereby facilitating manufacture and assembly. It is an object of the present invention to provide an oscillating swash plate type variable displacement compressor which can be performed.

[0014]

According to the present invention, in order to achieve the above object, in a swinging swash plate type variable displacement compressor, the discharge chamber and the crank chamber are communicated by an air supply passage, and the crank chamber and the suction chamber are communicated with each other. A first valve that adjusts the opening of the bleed passage in conjunction with a pressure-sensitive member that is operated by a pressure change in a first pressure-sensitive chamber that senses the pressure of the suction chamber. And an operating rod that is reciprocated by pressure fluctuations of a second pressure-sensitive chamber that senses a discharge pressure in the middle of the air supply passage so that the operating rod can be pressed against the first valve body. The operation rod is operatively connected, and the operation rod is further provided with a communication path that becomes a part of an air supply path. When the discharge pressure in the second pressure-sensitive chamber falls below a predetermined set value during a low cooling load, the communication path is To provide a second valve body to open the valve It is taking.

[0015]

According to the present invention, when the cooling load decreases and the pressure of the suction chamber acting on the first pressure-sensitive chamber decreases, the first pressure-sensitive member reduces the pressure of the first pressure-sensitive member.
The valve body is moved in a direction to decrease the valve opening of the bleed passage.
As a result, the flow rate of the refrigerant gas supplied from the crank chamber to the suction chamber decreases, and the crank chamber pressure is increased by the gas blow-by from the working chamber in the cylinder bore to the crank chamber, and the pressure difference between the crank chamber pressure and the suction pressure is increased. Increases, the inclination angle of the swash plate decreases, the stroke of the piston decreases, and the discharge capacity is reduced. Conversely, when the cooling load increases, the opening degree of the first valve body of the bleed passage increases, contrary to the above-described operation, and therefore, the flow rate of the refrigerant gas supplied from the crank chamber to the suction chamber increases, The differential pressure increases, the inclination angle of the swash plate increases, the stroke of the piston increases, and the discharge capacity increases.

Also, in proportion to the increase in the cooling load and the increase in the pressure in the discharge chamber, the pressure in the second pressure-sensitive chamber increases and the operating rod pushes the first valve body in the valve opening direction. , The first
The valve body is pushed in a direction to further open the bleed passage. For this reason, the refrigerant gas supplied from the crank chamber to the suction chamber through the bleed passage is increased, the differential pressure is reduced, the inclination angle of the swash plate is increased, the stroke of the piston is increased, and the discharged refrigerant gas amount is increased. Is increased. Therefore, as the cooling load increases, the suction pressure decreases, the pressure loss in the suction pipe from the evaporator to the compressor is compensated, the evaporation pressure of the evaporator is kept almost constant, and the cooling capacity is secured.

On the other hand, when the cooling load decreases and the discharge pressure falls below a predetermined set value, the second valve element provided on the operating rod is released by the urging force of the spring, and the second valve element is released from the discharge chamber to the crank chamber. Refrigerant gas is supplied, the differential pressure between the crank chamber and the suction chamber increases, the tilt angle of the swash plate decreases, the discharged refrigerant gas decreases, and the freezing of the evaporator under low load conditions is prevented. You.

According to the present invention, a communication passage serving as an air supply passage from a discharge chamber to a crank chamber is formed in an operation rod interlocked with a first valve body, and a second valve body for preventing freezing of an evaporator is provided in the operation rod. With the provision, the configuration of the pressure control valve can be simplified.

Further, according to the present invention, by adjusting the urging force of the spring for urging the second valve body, the opening / closing timing of the second valve body can be easily adjusted.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 3, a front housing 2 is joined and fixed to a front end of the cylinder block 1, and a rear housing 4 forming an intake chamber 4a and a discharge chamber 4b is joined and fixed to a rear end face via a valve plate 3. I have. The valve plate 3 has a suction chamber 4a.
A suction valve mechanism 5 capable of sucking refrigerant gas into a working chamber R in a cylinder bore 1a formed in the cylinder block 1 is provided, and a discharge valve mechanism 6 capable of discharging the refrigerant gas compressed in the working chamber R to a discharge chamber 4b. Is provided.

At the center of the cylinder block 1 and the front housing 2, a rotary shaft 7 is provided with a radial bearing 8.
Supported by A lug plate 9 is fitted and fixed to an intermediate portion of the rotating shaft 7, and a support arm 10 constituting a hinge mechanism is integrally formed on the outer periphery thereof so as to protrude.
A rotary swash plate 12 as a swing swash plate is swingably movable in the front-rear direction through a connecting pin 11 which also forms a hinge mechanism in a long hole 10 a formed in the arm 10.
It is supported to be able to rotate synchronously. The oscillating plate 13 is supported on the boss 12a of the rotary swash plate 12 so as to be relatively rotatable, and is rotatable only in the front-rear direction at a fixed position by a rotation preventing rod 14 fixed to the cylinder block 1 and the front housing 2. ing.

A slider 15 is supported on the rotating shaft 7 so as to be able to reciprocate in the axial direction. The slider 15 is connected to a boss 12 a of the rotary swash plate 12 by a connecting pin 16. The slider 15 is always urged by a spring 17 mounted on the rotating shaft 7 to a position where the tilting angle of the rocking plate 13 and the rotary swash plate 12 is maximized. The swing plate 13 is connected to a plurality of pistons 18 housed in the cylinder bore 1a via piston rods 19, respectively.

Therefore, when the rotating shaft 7 is rotated by the power of the engine and the lug plate 9, the connecting pin 11, and the rotary swash plate 12 are integrally rotated, the rocking plate 13 is rotated in the front-rear direction without rotating. The piston 18 is oscillated, and the piston 18 is reciprocated in the cylinder bore 1a via the piston rod 19.
Therefore, the refrigerant gas sucked into the working chamber R from the suction chamber 4a is compressed in the working chamber R and then discharged to the discharge chamber 4b. During this compression, the pressure Pc in the crank chamber 2a increases due to blow-by gas from the outer peripheral surface of the piston 18, which is adjusted by a displacement control device described below.

The capacity control device will now be described. An air supply passage connecting the discharge chamber 4b and the crank chamber 2a is provided in the cylinder block 1, the valve plate 3 and the rear housing 4 as shown in FIGS. 20 is formed, and a bleed passage 21 communicating the crank chamber 2a and the suction chamber 4a is formed. In addition, the piston 1
The pressure Pc of the crank chamber 2a also rises due to the gas blow-by through the gap on the outer periphery of the crankcase 8. The air supply passage 2
A pressure control valve 22 is interposed midway between the zero and the bleed passage 21.

The pressure control valve 22 will be described mainly with reference to FIG. 1. A valve chamber 24 is formed in a valve storage case 23, and a valve seat 23a formed in the case 23 in the valve chamber 24, that is, a bleed passage. A spherical first valve body 25 that opens and closes 21 is housed. This first valve body 25 is the case 2
The spring 2 interposed between the stopper 2 and the stopper 26 provided on the inner wall of the spring 3
7 is urged in a direction to release the bleed passage 21. Below the first valve body 25, a diaphragm 28 as a pressure-sensitive member is attached by a storage case 29,
A spacer 3 is provided between the diaphragm 28 and the first valve body 25.
0 is interposed. Further, a spring storage case 31 is attached to a lower portion of the storage case 29, and a spring 32 housed inside the storage case 29 is attached to the diaphragm 28 upward by spring receivers 33 and 34, that is, in a direction to close the first valve body 25. I'm going. A first pressure sensing chamber 35 is formed above the diaphragm 28, and the suction pressure P acting on the pressure sensing chamber 35 through the bleed passage 21 downstream of the first valve body 25.
s. When the suction pressure Ps is high, the first valve 25 is operated in the opening direction, and when the pressure Ps is low, the first valve 25 is operated in the closing direction.

An insertion hole 23b is formed in the upper part of the valve storage case 23, and the air supply passage 20 is formed in the insertion hole 23b.
Rod 3 integrally formed with a second valve body 36 for opening and closing the valve
7 is inserted and supported so as to be able to reciprocate vertically. The operating rod 37 is provided with a communication passage 37a which is a part of the air supply passage 20. The upper end of the communication passage 37a communicates with a second pressure-sensitive chamber 38 formed in the upper part of the case 23 through a valve hole 36a having a restriction of the second valve body 36. The lower part of the communication passage 37a is communicated with a spring accommodating chamber 23c which is a part of the air supply passage 20 or the bleed passage 21 below the insertion hole 23b. A cap 3 for partitioning the second pressure-sensitive chamber 38 is provided at the upper end of the case 23.
The second pressure sensing chamber 38 communicates with the discharge chamber 4 b through the air supply passage 20 on the upstream side of the second valve body 36 by a passage 39 a provided through the cap 39. A flange portion 37 provided on the outer periphery of the stopper 26 and the operating rod 37
A spring 40 for urging the second valve body 36 in the opening direction is interposed between the spring 40b and the spring 40b. When the discharge pressure Pd in the second pressure-sensitive chamber 38 becomes equal to or less than a predetermined set value, the operating rod 37 is moved and held at the uppermost end by the spring 40, and is moved by the valve hole 36a and the communication passage 37a. The two pressure-sensitive chambers 38 and the spring accommodating chamber 23c are communicated with each other so that refrigerant gas is supplied from the discharge chamber 4b to the crank chamber 2a through the air supply passage 20. Conversely, when the pressure Pd of the discharge chamber 4b acting on the second pressure-sensitive chamber 38 exceeds the set pressure and the operating rod 37 is moved downward against the urging force of the spring 40, the second valve body The valve hole 36a is closed by the upper inner peripheral wall of the insertion hole 23b to close the air supply passage 20, and the lower end surface 37c of the operating rod 37 is connected to the first
A variation in the discharge pressure Pd of the second pressure sensing chamber 38 is applied to the first valve body 25 via the operating rod 37 so as to contact the upper surface of the valve body 25 to adjust the valve opening of the bleed passage 21. I have to.

Next, the operation of the oscillating plate type variable displacement compressor constructed as described above will be described. When the compressor is stopped, the pressure Pd in the discharge chamber 4b, the pressure Pc in the crank chamber 2a, and the pressure Ps in the suction chamber 4a are substantially the same. Therefore, as shown in FIG. 1, the first valve body 25 of the pressure control valve 22 contacts the valve seat 23 a by the urging force of the spring 32 to close the bleed passage 21, and the operating rod 37 is moved upward by the spring 40. The valve hole 36a of the second valve body 36 is lifted and held at a position where the air supply passage 20 is released.

When the rotating shaft 7 of the compressor shown in FIG. 3 is rotated by the engine in a state where the temperature in the passenger compartment is high and the cooling load is high, the rotating swash plate 12 rotates through the lug plate 9 and the connecting pin 11. As a result, the rocking plate 13 is rocked in the front-rear direction, and the rocking motion causes the piston 18 to reciprocate in the cylinder bore 1 a via the rod 19. Therefore, the refrigerant gas is sucked from the suction chamber 4a into the working chamber R in the cylinder bore 1a, and the compressed gas is discharged to the discharge chamber 4b. Then, the pressure Pd in the discharge chamber 4b increases,
This pressure Pd acts on the second pressure-sensitive chamber 38 through the air supply passage 20. When the pressure Pd exceeds a predetermined value, the operating rod 37 receives a downward pressing force against the urging force of the spring 40, and the operating rod 37 is moved downward in FIG. 36a is closed, and the air supply passage 20 is moved in a direction to close. Then, as shown in FIG. 2, the lower end surface 37c of the operating rod 37 comes into contact with the upper surface of the first valve body 25, and the first valve body 25 is affected by the fluctuation of the discharge pressure Pd while the first pressure sensitive chamber 35 Suction pressure Ps and spring 27,
32, the crank chamber pressure P in the spring accommodating chamber 23c.
The valve opening control to the position where c is balanced is performed as follows.

For a while after the compressor is started, the refrigerant gas blown into the crank chamber 2a from the working chamber R in the cylinder bore 1a through the gap between the outer peripheral surface of the piston 18 and the inner peripheral surface of the bore 18 causes the inside of the crank chamber 2a. The pressure Pc increases. When the cooling load in the vehicle compartment is large and the suction pressure Ps is high, the pressure Ps in the first pressure sensing chamber 35 is also high, so that the first valve body 25 opens the bleed passage 21 in the crank chamber pressure Pc. , The first valve body 25 is opened as shown in FIG. 2, and the bleed passage 21 is kept open. For this reason, the refrigerant gas corresponding to the above-mentioned blow-by circulates from the crank chamber 2a to the suction chamber 4a, and the rise of the crank chamber pressure Pc is suppressed. Therefore, the crank chamber pressure Pc and the suction pressure P acting on the back surface and the working surface of the piston 18 are determined.
s does not change, and the compressor is operated in a large capacity state.

Then, when the operation of the compressor is continued, the cooling load in the passenger compartment decreases, and the suction pressure Ps decreases, the first
Since the pressure sensing chamber 35 senses this and the diaphragm 28 is displaced upward in FIG. 2, the first valve body 25 is pressed in a direction to close the bleed passage 21, and the refrigerant flows from the crank chamber 2a to the suction chamber 4a. Gas emissions are reduced. For this reason, the crank chamber pressure Pc acting on the back of the piston 18
Is increased by the blow-by gas, the differential pressure ΔPcs increases, the inclination angle of the swing plate 13 decreases, and the discharge capacity decreases in accordance with the reduction of the cooling load.

The first valve body 25 is affected by the discharge pressure Pd by the second pressure sensing chamber 38 and the operating rod 37. When the pressure in the second pressure sensing chamber 38 increases as the discharge pressure Pd increases in FIG. 5, the operating rod 37 is pressed more strongly in the direction in which the first valve body 25 is opened in FIG. . For this reason, the discharge amount of the refrigerant gas from the crank chamber 2a to the suction chamber 4a increases, and the differential pressure ΔPcs tends to decrease, the inclination angle of the swing plate 13 increases, and the discharge capacity gradually increases. . Accordingly, the suction pressure Ps decreases with an increase in the discharge pressure Pd. Therefore, even if the pressure loss of the refrigerant gas in the pipe sucked into the compressor from the evaporator increases with the increase in the discharge pressure Pd, the evaporator does not. Evaporating pressure Pe is compensated for the pressure loss and is kept substantially constant, so that the cooling capacity under a high load is ensured.

On the other hand, when the cooling load in the passenger compartment is reduced and the compressor is operated in a small capacity range, the discharge pressure Pd
Also decrease. When this pressure Pd falls below a predetermined set value,
The pressure in the second pressure sensing chamber 38 also decreases, and the operating rod 37 is separated from the first valve body 25 by the spring 40, and the valve body 25
The bleed passage 21 is moved to a position where the bleed passage 21 is closed due to a decrease in the pressure Ps in the pressure sensing chamber 35. Further, the valve hole 36a of the second valve body 36 provided on the operating rod 37 is displaced to a position where the air supply passage 20 is opened as shown in FIG. Therefore, refrigerant gas is supplied from the discharge chamber 4b to the crank chamber 2a through the air supply passage 20, and the pressure Pc in the crank chamber 2a further increases,
The tilt angle of the rocking plate 13 decreases, and the discharge capacity decreases.
As a result, the evaporation pressure of the evaporator decreases, and freezing of the evaporator is prevented.

Now, in the first embodiment of the present invention,
Since the second valve body 36 for preventing the freezing of the evaporator is formed integrally with the operating rod 37 for giving the influence of the discharge pressure Pd to the first valve body 25, the valve structure is simplified to manufacture and assemble. Can be easily performed, and the cost of the control valve can be reduced.

Further, when the discharge pressure Pd becomes equal to or less than the predetermined set value, the opening / closing operation point of the second valve body 36 can be easily adjusted by changing the urging force of the spring 40. Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, the first valve element 41
Operating rod 42 having a communication passage 42a at the top of the cylinder
Are formed integrally, and the upper end of the rod 42 is provided with an air supply passage 2.
It supports a second valve body 43 for opening and closing the communication passage 42a which becomes zero. The second valve body 43 is urged by a spring 44 in a direction to open the communication passage 42a, that is, the air supply passage 20. The second valve body 43 is brought into contact with the lower surface of a stopper 45 having a passage 45a provided above the insertion hole 23b by the urging force of a spring 44.

Therefore, in the second embodiment, when the discharge pressure Pd is equal to or higher than the predetermined value, the second valve body 43 closes the communication passage 42a, that is, the air supply passage 20.
The first pressure fluctuation of the discharge pressure Pd is
It is transmitted to the valve body 41. For this reason, the suction pressure Ps decreases in proportion to the rise of the discharge pressure Pd, and the pressure Pe of the evaporator is kept almost constant, so that the same capacity control characteristic as in the first embodiment can be obtained.

Further, when the cooling load is reduced, the discharge pressure P
When d becomes equal to or less than a predetermined set value, the second valve body 43 is separated from the upper end surface of the operating rod 42 by the urging force of the spring 44, so that the air supply passage 20 is released and the discharge chamber 4b is separated from the crank chamber. A refrigerant gas is supplied to 2a. For this reason, the inclination angle of the rocking plate 13 is reduced, the stroke of the piston 18 is reduced, the discharge capacity of the compressor is reduced, and freezing of the evaporator is prevented.

Also in the second embodiment, the first valve body 41
Since the operating rod 42 is formed on the upper part of the valve and the second valve body 43 is supported on the upper end of the operating rod 42 by the spring 44, the configuration of the pressure control valve can be simplified. Further, in the second embodiment, the setting of the opening / closing operation point of the air supply passage 20 of the second valve body 43 when the discharge pressure Pd becomes equal to or less than a predetermined set value is easily performed by adjusting the urging force of the spring 44. be able to.

The present invention is not limited to the above embodiment, but can be embodied as follows. (1) As shown in FIG. 7, a communication groove 46 a having a throttle serving as the air supply passage 20 is formed on the outer peripheral surface of the operation rod 46 connected to the valve body 25 or 41, and the air supply passage is formed in the case 23. A communication path 47 which is 20 is formed. When the discharge pressure Pd falls below a predetermined set value and the operating rod 46 is moved upward, the second pressure-sensitive chamber 38 and the communication passage 47 are connected by the communication groove 46a, and the discharge chamber 4b is moved from the discharge chamber 4b to the crank chamber 2a. May be supplied with a refrigerant gas.

(2) A bellows (not shown) is used in place of the diaphragm 28.

[0041]

As described above in detail, according to the present invention, when the discharge pressure increases, the suction pressure is reduced to compensate for the pressure loss in the suction pipe from the evaporator to the compressor, thereby increasing the pressure in the evaporator. The evaporator can be kept substantially constant, the freezing of the evaporator in the low discharge pressure region can be reliably prevented, the structure of the pressure control valve can be simplified, and the production and assembly can be easily performed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a stopped state of a pressure control valve of an oscillating plate type variable displacement compressor embodying the present invention.

FIG. 2 is a longitudinal sectional view showing an operation state of a pressure control valve.

FIG. 3 is a sectional view of a variable displacement compressor.

FIG. 4 is a circuit diagram showing a relationship between a pressure control valve and a discharge chamber, a crank chamber, and a suction chamber.

FIG. 5 is a graph showing a relationship between a discharge pressure and a suction pressure.

FIG. 6 is a longitudinal sectional view of a pressure control valve showing another embodiment of the present invention.

FIG. 7 is a partial longitudinal sectional view of a pressure control valve showing another embodiment of the present invention.

[Explanation of symbols]

1 cylinder block, 2 front housing, 2a
Crank chamber, 4 rear housing, 4a suction chamber, 4
b discharge chamber, 7 rotating shafts, 9 lug plates, 10 support arms constituting a hinge mechanism, 11 connecting pins constituting a hinge mechanism, 12 rotating swash plate as a swinging swash plate, 1
3 rocking plate, 18 piston, 20 air supply passage, 21
Bleed passage, 22 pressure control valve, 23 valve storage case, 2
3a Valve seat, 25, 41 First valve body, 27, 32, 44
Spring, 28 Diaphragm as pressure sensing member, 35
First pressure sensing chamber, 36, 43 Second valve body, 36a Valve hole, 3
7, 42, 46 operating rod, 37a, 42a, 47
Communication passage, 46a Communication groove, 38 Second pressure-sensitive chamber.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F04B 27/14

Claims (1)

(57) [Claims] A swinging swash plate for reciprocating a piston with respect to a rotary shaft is provided so as to be tiltable by a hinge mechanism, and the crank chamber pressure, the suction pressure and The tilt angle of the swash plate changes in accordance with the differential pressure of the swash plate, and the stroke of the piston changes to control the discharge capacity. Through the air supply passage, and the crank chamber and the suction chamber through the bleed passage.
The bleed passage is provided with a first valve body that adjusts an opening degree of the bleed passage in conjunction with a pressure-sensitive member that is operated by a pressure change of a first pressure-sensitive chamber that senses a pressure of a suction chamber. In the middle of the passage, there is provided an operating rod which is reciprocated by the pressure fluctuation of the second pressure sensing chamber for sensing the discharge pressure, and the operating rod is operably connected to the first valve body so as to be able to be pressed. The rod is provided with a communication passage which is a part of an air supply passage, and opens the communication passage when the discharge pressure in the second pressure-sensitive chamber becomes equal to or less than a predetermined set value during a low cooling load.
Swinging swash plate type variable displacement compressor equipped with a valve element.