JPH06200875A - Rocking swash plate type variable displacement compressor - Google Patents

Abstract

PURPOSE:To easily adjust control characteristics which control the opening of a valve body by sensing fluctuation in discharge pressure, and thereby changing the pressure bearing area for the pressure sensing member of a pressure sensing chamber. CONSTITUTION:A crank room 2a is communicated with an inlet chamber 4a by an air bleed passage 21. A valve body 25 is provided for the air bleed passage 21, which is actuated by a diaphragm 28 operated by the pressure fluctuation of a first pressure sensing chamber 34 sensing the pressure Ps of the inlet chamber 4a for adjusting the opening of the air bleed passage 21. Moreover, a second pressure sensing chamber 35 is provided for the inside of the valve body 25, and a communication cylinder 37 is provided for the valve body 25, which allows discharge pressure Pd to be applied to the second pressure sensing chamber 35 through a discharge chamber 4b.

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 swing swash plate type in which a discharge capacity is varied by adjusting a pressure in a crank chamber accommodating a swing swash plate to change an inclination angle of the swing swash plate As a variable capacity compressor, for example, JP-A-62-2947
There is one disclosed in Japanese Patent No. 81.

The pressure in the crank chamber of the compressor of this type is formed by the pressure leaking between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston, that is, the blow-by gas pressure. Therefore, the pressure in the crank chamber is on the low pressure side. It will be higher than the suction pressure. Also, when the load is high, that is, when the suction pressure exceeds a predetermined set value, the pressure control valve installed in the extraction passage between the crank chamber and the suction chamber opens, and the pressure in the crank chamber (blow-by gas) Flows into the inhalation chamber. As a result, the pressure in the crank chamber decreases, and the inclination angle of the swash plate increases, the stroke of the piston increases, and the discharge capacity increases. On the other hand, when the heat load decreases (medium load state) and the suction pressure decreases, the opening degree of the pressure control valve decreases as the suction pressure decreases, which causes the pressure in the crank chamber to flow into the suction chamber. The amount to do decreases. For this reason, the pressure in the crank chamber rises, and the inclination angle of the swing swash plate becomes smaller accordingly, the stroke of the piston becomes smaller, and the discharge capacity decreases. The discharge capacity is changed by such an operation.

Generally, 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 the fluid occurs in the suction pipe or the like. This pressure loss increases to about 0.5 Kg / cm ² when the flow rate is high (when the flow rate is high). 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 outlet pressure of the evaporator is 2 to 2 depending on the cooling load.
It changes to 2.5 Kg / cm ² G. Therefore, when the cooling load is high, the flow rate of the refrigerant gas increases and the pressure loss in the suction pipe increases, so that the evaporator pressure rises, the cooling capacity becomes insufficient, and the cooling feeling deteriorates. .

In order to solve the above-mentioned problems, there is a conventional method disclosed in Japanese Patent Laid-Open No.
A variable capacity compressor disclosed in Japanese Patent Publication No. 142276 has been proposed. The compressor includes an extraction 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 extraction passage. This control device includes an opening / closing valve that opens / closes the bleed passage by detecting the pressure in the suction chamber or the pressure in the crank chamber. Further, there is provided operating point control means for applying a load generated by the pressure of the discharge chamber to the opening / closing valve to move the opening / closing operating point of the opening / closing 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, and the rod causes the on-off valve to be generated by the pressure of the discharge chamber. It is designed to transfer the load.

According to the conventional compressor, the bleed passage between the suction chamber and the crank chamber is opened / closed by the open / close valve in response to the change in the pressure of the suction chamber or the crank chamber. 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 also adjusted according to the pressure in the discharge chamber, so that the above-described pressure loss in the suction pipe can be eliminated and proper cooling can be performed.

[0007]

The suction pipe from the evaporator to the compressor is different depending on the cooling system of the vehicle type used, and the pressure loss of the pipe is different. Therefore, the pressure of the evaporator is properly adjusted accordingly. There is a need to. However, since the above-mentioned conventional compressor capacity control device applies the discharge pressure to the end surface of the actuating rod on the discharge chamber side, the pressure receiving area on which the discharge pressure acts is changed to change the evaporation pressure as described above. There is a problem that it is very troublesome to properly adjust the pressure of the vessel and change the control performance of the pressure control valve. If the conventional control device is to be adjusted, it is necessary to change and adjust the outer diameter of the actuating rod and the inner diameter of the insertion hole of the case accommodating the actuating rod, which requires manufacturing and assembling of various parts. There was a problem of becoming.

The object of the present invention is to solve the above problems existing in the prior art and to compensate the pressure loss of the suction pipe from the evaporator to the compressor by lowering the suction pressure when the discharge pressure becomes high. It is an object of the present invention to provide an oscillating swash plate type variable displacement compressor that can keep the pressure of the evaporator substantially constant and can easily adjust the control characteristics of the pressure control valve.

[0009]

In order to achieve the above object, the present invention comprises a suction chamber, a discharge chamber and a crank chamber,
A swing swash plate for reciprocating the piston with respect to the rotating shaft is mounted so as to be tiltable by a hinge mechanism, and the tilt angle of the swing swash plate is changed according to the pressure difference between the crank chamber pressure and the suction pressure. In the swing swash plate type variable displacement compressor configured to control the discharge capacity, the discharge chamber and the crank chamber are communicated with each other through the air supply passage, the crank chamber and the suction chamber are communicated with each other through the bleed passage, and the bleed passage is connected to the bleed passage. Is a pressure control valve that includes a pressure-sensitive member that is operated by pressure fluctuations in the first pressure-sensitive chamber that senses the pressure in the suction chamber, and a valve body that is operated by the pressure-sensitive member and that adjusts the opening degree of the extraction passage. A second pressure-sensitive chamber is provided inside the valve body, and a communication cylinder that communicates the discharge chamber with the second pressure-sensitive chamber and applies a discharge pressure to the pressure-sensitive member is provided in the valve body. I am taking means.

[0010]

According to the present invention, when the cooling load decreases and the pressure in the suction chamber acting on the first pressure sensitive chamber decreases, the valve body of the pressure control valve reduces the valve opening degree of the bleed passage by the pressure sensitive member. Be moved. Therefore, the flow rate of the refrigerant gas supplied from the crank chamber to the suction chamber is reduced, and the crank chamber pressure is increased by the gas blow-by from the working chamber in the cylinder bore to the crank chamber, resulting in a differential pressure between the crank chamber pressure and the suction pressure. Is increased, the tilt angle of the swing swash plate is reduced, the stroke of the piston is reduced, and the discharge capacity is reduced. On the contrary, when the cooling load increases, the opening degree of the valve body in the extraction passage is increased contrary to the above-mentioned action, and therefore the flow rate of the refrigerant gas supplied from the crank chamber to the suction chamber increases, and the differential pressure is increased. Is increased, the inclination angle of the swing swash plate is increased, the stroke of the piston is increased, and the discharge capacity is increased.

Further, when the cooling load increases and the pressure in the discharge chamber increases, the discharge pressure acting on the second pressure sensing chamber through the communication cylinder also increases, and therefore the valve of the pressure control valve acting on the pressure sensing member. The load in the direction of opening the body increases, and the valve body is pushed in the direction of further opening the bleed passage. Therefore, the refrigerant gas supplied from the crank chamber to the suction chamber through the bleed passage is increased, the differential pressure is decreased, the tilt angle of the swash plate is increased, and the stroke of the piston is increased. Is increased. Therefore, as the cooling load increases and the discharge pressure increases, the suction pressure decreases, the pressure loss of the suction pipe from the evaporator to the compressor is compensated, and the evaporation pressure of the evaporator is maintained almost constant, and the cooling capacity is reduced. Secured.

According to the present invention, the second pressure-sensitive chamber is formed inside the valve body, and the discharge pressure acts on the second pressure-sensitive chamber through the communication cylinder. The discharge pressure acts on the pressure-sensitive member such as a diaphragm or a bellows. The pressure adjustment of the discharge pressure to the valve body can be easily performed by changing the pressure receiving area of the pressure sensing member by the second pressure sensing chamber.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. As shown in FIG. 2, a front housing 2 is joined and fixed to a front end portion of a cylinder block 1, and a suction chamber 4a is attached to a rear end surface of the cylinder block 1 via a valve plate 3.
The rear housing 4 forming the discharge chamber 4b is fixedly joined. The valve plate 3 is provided with a suction valve mechanism 5 capable of sucking the refrigerant gas from the suction chamber 4a to the working chamber R in the cylinder bore 1a formed in the cylinder block 1.
A discharge valve mechanism 6 capable of discharging the refrigerant gas compressed in the working chamber R to the 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.
It is supported by. A lug plate 9 is fitted and fixed to an intermediate portion of the rotary shaft 7, and a support arm 10 forming a hinge mechanism is integrally formed on the outer periphery of the lug plate 9 so as to project therefrom.
Further, a rotary swash plate 12 is supported in the elongated hole 10a formed in the arm 10 via a connecting pin 11 which also constitutes a hinge mechanism so as to be swingable in the front-back direction and rotatable in synchronization with the rotary shaft 7. There is. The swash plate 13 is supported on the boss portion 12a of the rotary swash plate 12 so that the swash plate 13 can rotate relative to the swash plate 12, and the rotation preventing rod 14 fixed to the cylinder block 1 and the front housing 2 can only tilt in the front-back direction at a fixed position. Has been done.

A slider 15 is supported on the rotating shaft 7 so as to be capable of reciprocating in the axial direction, and the slider 15 is connected to a boss portion 12a of the rotating swash plate 12 by a connecting pin 16. The slider 15 is always provided with a spring 17 mounted on the rotary shaft 7 so that the swing swash plate 13 and the rotary swash plate 12 are always provided.
Is biased to a position where the inclination angle is maximum. The swing swash plate 13 is articulated via a plurality of pistons 18 and piston rods 19 housed in the cylinder bore 1a.

Therefore, when the rotary 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 swing swash plate 13 is in a non-rotating state in the front-rear direction. The piston 18 reciprocates in the cylinder bore 1a via the piston rod 19. Therefore, the refrigerant gas sucked from the suction chamber 4a into the working chamber R is compressed in the working chamber R and then discharged into the discharge chamber 4b. At the time of this compression, the blow-by gas from the outer peripheral surface of the piston 18 increases the pressure Pc in the crank chamber 2a, which is adjusted by the pressure control valve 22 described below.

Therefore, the pressure control valve 22 will be described. The cylinder block 1, the valve plate 3 and the rear housing 4 have a throttle 20a for communicating the discharge chamber 4b with the crank chamber 2a as shown in FIG. An air supply passage 20 is formed, and an extraction passage 21 that connects the crank chamber 2a and the suction chamber 4a is formed. In this embodiment, it is assumed that the air supply passage 20 is formed only by the gap between the piston 18 that blows the refrigerant gas from the working chamber R in the cylinder bore into the crank chamber 2a and the cylinder bore 1a. A pressure control valve 22 is provided in the middle of the extraction passage 21.
Is intervening.

The pressure control valve 22 will be described with reference to FIG. A valve body 25 for opening and closing 21 is housed. The valve body 25 is biased in a direction of releasing the bleed passage 21 by a spring 27 interposed between the valve body 25 and a stopper 26 provided on the inner wall of the case 23. Below the valve body 25, a diaphragm 28 as a pressure sensitive member is provided.
Is attached by the storage case 29. Further, a spring storage case 30 is attached to the lower portion of the storage case 29, and a spring 31 housed therein has a spring receiver 32,
The diaphragm 28 is biased upward by 33, that is, in the direction of closing the valve body 25. The storage case 3
The interior of 0 is an atmospheric pressure or a closed constant pressure chamber. The upper side of the diaphragm 28 is a first pressure sensing chamber 34, and the pressure sensing chamber 34 senses the suction pressure Ps acting through the bleed passage 21 on the downstream side of the valve body 25 to open / close the valve body 25.

A cylindrical portion 25a is provided below the valve body 25.
Are integrally formed, and the pressure Pd of the discharge chamber 4b is
A second pressure-sensitive chamber 35 for sensing is formed. An insertion hole 36 is vertically formed through the upper portion of the valve housing case 23, and a communication cylinder 37 is inserted into and supported by the insertion hole 36 so as to be vertically slidable. The communication cylinder 37 is formed integrally with the valve body 25, and the second pressure sensing chamber 35 is communicated with a third pressure sensing chamber 39 formed immediately above the case 23 by a communication passage 38 formed in the communication cylinder 37. ing. The third pressure sensitive chamber 39 is communicated with the discharge chamber 4b by a communication passage 40 formed in the rear housing 4. Therefore, the pressure Pd of the discharge chamber 4b acts on the second pressure sensitive chamber 35 through the communication passage 40, the third pressure sensitive chamber 39, and the communication passage 38, and the diaphragm 28.
Discharge pressure P to the pressure receiving surface 28a corresponding to the pressure sensitive chamber 35 of
A load proportional to d is exerted, and participates in the opening / closing operation of the valve body 25.

Next, the operation of the swing swash plate type variable displacement compressor configured 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 valve body 25 of the pressure control valve 22 is held at a position where it abuts the valve seat 23a by the biasing force of the spring 31 and closes the bleed passage 21.

When the rotating shaft 7 of the compressor shown in FIG. 2 is rotated by the engine in the state where the temperature inside the vehicle compartment is high and the cooling load is high, the rotating swash plate 12 rotates via the lug plate 9 and the connecting pin 11. As a result, the swing swash plate 13 is swung in the front-rear direction, and the swing motion causes the piston 18 to reciprocate in the cylinder bore 1a via the rod 19.
Therefore, from the suction chamber 4a to the working chamber R in the cylinder bore 1a.
The refrigerant gas is sucked into the discharge chamber 4b and the compressed gas is discharged into the discharge chamber 4b. Then, the pressure Pd in the discharge chamber 4b rises, and this pressure Pd acts on the second pressure sensing chamber 35 through the communication passage 40, the third pressure sensing chamber 39 and the communication passage 38, and the pressure sensing chamber 35 of the diaphragm 28. And acts on the pressure receiving surface 28a corresponding to, and affects the opening / closing operation of the valve body 25. The valve body 25 is affected by the variation of the discharge pressure Pd described above, and balances the suction pressure Ps of the first pressure sensing chamber 34, the biasing forces of the springs 27 and 31, the crank chamber pressure Pc in the spring accommodating chamber 23b, and the like. The control to the position to be performed is performed as follows.

For a while after the start of the compressor, the pressure in the crank chamber 2a is increased by the refrigerant gas blown from the working chamber R in the cylinder bore 1a to the crank chamber 2a through the gap between the outer peripheral surface of the piston 18 and the inner peripheral surface of the bore. Pc rises.
When the cooling load in the vehicle compartment is large and the suction pressure Ps is high, the pressure Pc in the first pressure-sensitive chamber 34 is also high. Therefore, the valve body 25 moves in the direction in which the bleed passage 21 is opened. Then, the valve body 25 is opened in FIG. 1 and the extraction passage 21 is released. Therefore, the refrigerant gas corresponding to the blow-by portion described above circulates from the crank chamber 2a to the suction chamber 4a, and the increase in the crank chamber pressure Pc is suppressed.
Therefore, the differential pressure ΔPcs between the crank chamber pressure Pc and the suction pressure Ps acting on the back surface and the working surface of the piston 18 does not change, and the compressor is in the large capacity state with the inclination angle of the swing swash plate 13 being the maximum. Be driven in.

When the compressor continues to operate, the cooling load in the passenger compartment decreases, and the suction pressure Ps decreases, the first
The pressure sensing chamber 34 detects this and the diaphragm 28 is displaced upward in FIG.
Is pressed in the direction to close the valve, and the discharge amount of the refrigerant gas from the crank chamber 2a to the suction chamber 4a is suppressed. Therefore, the crank chamber pressure Pc acting on the back surface of the piston 18 is increased by the blow-by gas from the working chamber R, and the differential pressure Δ
Pcs increases, the inclination angle of the swash plate 13 decreases, and the discharge capacity decreases as the cooling load decreases.

By the way, the valve body 25 has a second pressure sensing chamber 35.
Is affected by the discharge pressure Pd that acts on. As the discharge pressure Pd increases in FIG. 4, the second pressure sensing chamber 35
When the pressure Pd of the diaphragm 2 increases, the diaphragm 2 in FIG.
The pressure receiving surface 28a of 8 is pressed downward, and the valve body 25 is pressed more strongly in the opening direction. Therefore, the discharge amount of the refrigerant gas returned from the crank chamber 2a to the suction chamber 4a through the bleed passage 21 increases, the differential pressure ΔPcs tends to decrease, and the inclination angle of the swing swash plate 13 increases. The discharge capacity is gradually increased. Therefore, since the suction pressure Ps decreases in proportion to the increase of the discharge pressure Pd, even if the pressure loss of the suction pipe from the evaporator to the compressor increases with the increase of the discharge pressure Pd, the evaporation pressure of the evaporator does not change. The pressure loss is compensated and kept almost constant, so that the cooling capacity at high load is secured.

In the above embodiment, the valve body 25 is provided with the communication cylinder 37 for giving the influence of the discharge pressure Pd, and the valve body 25 is provided with the second pressure sensitive chamber 35 for acting the discharge pressure Pd. By changing the area of the pressure receiving surface 28a of the second pressure sensing chamber 35 with respect to the diaphragm 28, the load of the discharge pressure Pd for the opening / closing control of the valve body 25 can be easily adjusted according to the cooling system.

In another example shown in FIG. 5, a fixed communication cylinder 37 is integrally formed on the upper part of the case 23, and a through hole 25b formed in the center of the valve body 25 with respect to the outer peripheral surface of the communication cylinder 37.
Is slidably fitted. In this example, the weight of the valve body 25 is reduced, so that the opening / closing control operation of the valve body 25 is smoothly performed.

The example shown in FIG. 6 is different from the example shown in FIG. 5 in that the communication tube 37 is formed separately from the case 23, and the flange portion 37a formed at the upper end of the communication tube 37 is formed in the case 23.
Is locked to the upper end surface of. Further, a gap g is provided between the outer peripheral surface of the communication cylinder 37 and the inner peripheral surface of the insertion hole 36 of the case 23. In this another example, it is possible to design the valve body 25, the communication cylinder 37, the valve seat 23a, and the like with a large degree of intersection with respect to the coaxiality.

In another example shown in FIG. 7, the flange portion of the communication cylinder 37 serves as a valve body 41 for opening and closing the air supply passage 20 (different from the blow-by gas gap of the piston 18) which communicates the discharge chamber 4b with the crank chamber 2a. It has a function. Further, the spring 27 is interposed between the valve body 25 and a locking portion 37b formed on the communication cylinder 37.

In this another example, when the discharge pressure Pd acting on the third pressure-sensitive chamber 39 becomes equal to or lower than a predetermined set value, the communication cylinder 37 is moved upward by the elastic force of the spring 27 and the valve body 41. Thus, the air supply passage 20 is opened, and the crank chamber pressure Pc is increased by the high-pressure refrigerant gas supplied from the discharge chamber 4b to the crank chamber 2a through the air supply passage 20. Therefore, the differential pressure ΔPcs acting on the piston 18 is increased, the inclination angle of the swash plate 13 can be reliably reduced in the low discharge pressure range, the discharge capacity can be reduced, and the evaporator can be prevented from freezing. Becomes

The present invention is not limited to the above embodiment, but can be embodied as follows. (1) Use a bellows (not shown) in place of the diaphragm 28.

(2) The communication tube 37 is a flexible pipe.

[0032]

As described in detail above, according to the present invention, it is easy to adjust the control characteristic for sensing the fluctuation of the discharge pressure and controlling the opening degree of the valve body by changing the pressure receiving area of the pressure sensitive chamber with respect to the pressure sensitive member. When the discharge pressure rises, the suction pressure can be reduced and the evaporation pressure of the evaporator can be controlled to be almost constant regardless of the pressure loss in the suction pipe. There is an effect that can suppress the lack of.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional view of a swing swash plate type variable displacement compressor.

FIG. 3 is a circuit diagram showing a relationship among a discharge chamber, a crank chamber, a suction chamber, and a pressure control valve.

FIG. 4 is a graph showing the relationship between discharge pressure, suction pressure, and evaporator pressure.

FIG. 5 is a cross-sectional view showing another example of the pressure control valve of the present invention.

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

FIG. 7 is a cross-sectional view showing another example of the pressure control valve 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 rotary shaft, 9 lug plate, 10 support arm that constitutes hinge mechanism, 11 connecting pin that constitutes hinge mechanism, 13 swing swash plate, 18 piston, 2
0 air supply passage, 21 bleed passage, 22 pressure control valve, 23
Valve housing case, 23a valve seat, 25 valve body, 27 spring, 28 diaphragm as pressure sensitive member, 34 first
Pressure-sensitive chamber, 35 Second pressure-sensitive chamber, 37 Communication tube, 38, 40
Communication passage, 39 Third pressure sensitive chamber.

Claims (1)

[Claims] 1. A swing swash plate having a suction chamber, a discharge chamber, and a crank chamber for reciprocating a piston with respect to a rotating shaft is mounted so as to be tiltable by a hinge mechanism. In the swing swash plate type variable displacement compressor in which the tilt angle of the swing swash plate is changed in accordance with the differential pressure to control the discharge capacity, the discharge chamber and the crank chamber are connected by an air supply passage. A pressure-sensing member operated by pressure fluctuation of the first pressure-sensitive chamber for sensing the pressure of the suction chamber, and operated by the pressure-sensing member, A pressure control valve including a valve body for adjusting the opening degree of the extraction passage is provided, a second pressure sensing chamber is provided inside the valve body, and a discharge chamber and a second pressure sensing chamber are provided in the valve body. Oscillating swash plate type that is provided with a communication tube that communicates the pressure-sensitive member with the discharge pressure Strange capacity compressor.