JPH04234580A - Variable capacity compressor - Google Patents

Abstract

PURPOSE:To make the discharge capacity of a compressor zero capacity, to prevent frost of an evaporator during low cooling load operation, to prevent a starting shock of the compressor, and further to omit a clutch for starting the compressor. CONSTITUTION:Even if a rotary driving shaft 16 is rotated, with a swash plate 22 of a compressor 3 held in a zero capacity position, the compression operation is not conducted because the stroke of an operating piston 20 is zero. When the first switching valve 74 is opened, coolant gas corresponding to the discharge pressure stored in a pressure accumulating tank 72 is supplied to a starting control pressure chamber 39 through a pipeline 71, so that a control piston 35 is moved to the right. Thus, the swash plate 22 is tilted, with the supporting shaft 33 as the center, and the compression operation is conducted by the operating piston 20.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement compressor used, for example, as an air conditioner for automobiles.

0002

[Prior Art] As a conventional swash plate type variable displacement compressor,
What is shown in Japanese Unexamined Patent Publication No. 54-5205 has been proposed. This compressor includes a housing having a plurality of cylinder bores arranged around a rotational drive shaft, an operating piston slidably fitted in each cylinder bore, and each connected to the operating piston via a piston rod. a swash plate; a rotation support that supports the swash plate and is swingable around the axis of a support shaft perpendicular to the axis of the rotation drive shaft and connected to the rotation drive shaft; the rotation support and the swash plate; The control piston is connected to the rotary support and moves according to the pressure in the capacity control pressure chamber to adjust the operating stroke of the operating piston by changing the inclination angle about the support shaft axis of the compressor. In order to control the discharge capacity according to the suction pressure, a control valve is interposed between the suction chamber and discharge chamber of the compressor and the capacity control pressure chamber.

[0003] When the temperature inside the vehicle increases, the cooling load increases, and the suction pressure increases, the control valve stops supplying pressure from the discharge chamber to the capacity control pressure chamber, so that the control piston The rotating support body and the swash plate are tilted in a direction to increase the capacity around the spindle axis. In addition, when the cooling load decreases, the suction pressure decreases and the control valve supplies high-pressure refrigerant gas in the discharge chamber to the capacity control pressure chamber. tilted in the direction of decrease.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned swash plate variable displacement compressor, when the angle of inclination of the swash plate becomes zero in the stopped state and the discharge capacity is zero, the compressor is started. At this time, the discharge pressure cannot be ensured, so the inclination angle of the swash plate is usually set so that the minimum capacity is about 10%. For this reason, there is a problem in that the discharge capacity becomes excessive in a low cooling load operating state and frost occurs in the evaporator. Furthermore, even if the minimum capacity of the compressor is set to about 10%, it is actually difficult to increase the discharge pressure required for recovery at the time of startup, and therefore, it is difficult to increase the discharge pressure required for recovery at the time of startup. Spring is also used. In this case, since the minimum capacity is restored to approximately 40% when the compressor is stopped, there is a problem in that a shock occurs at startup, giving a sense of discomfort to the driver.

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, to reduce the discharge capacity to 0%, and to alleviate the frost of the evaporator and the shock at the time of starting the compressor. An object of the present invention is to provide a variable capacity compressor that can eliminate a clutch for starting the compressor.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a housing having a plurality of cylinder bores arranged around a rotational drive shaft, and an operating piston slidably fitted into each cylinder bore. a swash plate connected to each operating piston via a piston rod, the swash plate supporting the swash plate and swingable about the axis of a support shaft perpendicular to the axis of the rotation drive shaft; a rotating support connected to the shaft; and a rotating support connected to the rotating support for adjusting the operating stroke of the operating piston by changing the inclination angle of the rotating support and the swash plate about the axis of the support shaft, and a displacement control member connected to the rotating support for adjusting the operating stroke of the operating piston. a control piston that moves according to the pressure of the pressure chamber, and a suction chamber and a discharge chamber of the compressor, and a control piston that moves according to the pressure of the variable displacement compressor according to the suction pressure. a capacity control valve interposed between the compressor, a pressure accumulator communicating with the discharge chamber of the compressor via a pipe and for sealingly holding the discharged refrigerant gas, and a capacity control pressure chamber of the control piston; An on-off valve is connected to a conduit between a startup control pressure chamber provided on the opposite side and the pressure accumulator, and an on-off valve is connected to a conduit between the discharge chamber and the pressure accumulator of the compressor, and the valve is connected to a conduit between the discharge chamber and the pressure accumulator. It is configured by a valve that allows movement into the pressure accumulation chamber and prevents backflow, and a control device that controls opening and closing of the opening/closing valve based on an operating signal of the compressor.

[0007]

[Operation] In this invention, when the compressor is stopped and the swash plate is held at the zero capacity position, and the on-off valve is closed and the discharged refrigerant gas is held in the pressure accumulator, the rotary drive shaft of the compressor is rotated. Even when rotated, no compression action takes place. Thereafter, when the on-off valve is opened in response to an open signal output from the control device to start the compressor, the discharged refrigerant gas stored in the pressure accumulation chamber is supplied into the start-up control pressure chamber through the conduit. Then, the control piston moves the rotary support body and the swash plate in a direction that increases the stroke of the operating piston, so that the rotation of the rotary drive shaft is transmitted to the swash plate through the rotary support body as a rocking motion in the front and rear direction. , the operation piston compresses the suction refrigerant gas. The opening/closing valve is closed by a closing signal from the control device when the swash plate is tilted to a predetermined capacity position.

After that, the discharge refrigerant gas supplied to the capacity control pressure chamber is adjusted by the capacity control valve based on the suction pressure, which varies depending on the size of the cooling load. The inclination angle of the swash plate is controlled by the piston, and an appropriate discharge capacity can be obtained. A part of the refrigerant gas discharged from the discharge chamber during operation of the compressor is guided to the pressure accumulation chamber through the pipe and the valve that prevents backflow when the on-off valve is closed. The discharged refrigerant gas is stored, and this refrigerant gas is used at the next start-up of the compressor.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings. As shown in FIG. 3, a condenser 3 is connected to the discharge flange 48 of the variable displacement compressor 1 via a discharge line 2, a receiver 5 is connected to the condenser 3 via a line 4, and a receiver 5 is connected to the condenser 3 via a line 4. An expansion valve 7 is connected to the receiver 5 via a conduit 6. Further, an evaporator 9 is connected to the expansion valve 7 via a conduit 8, and the evaporator 9 is connected to a suction flange 47 of the compressor via a conduit 10.

Next, the configuration of the variable displacement compressor 1 will be explained with reference to FIG. The compressor housing 11 includes a center housing 12 , a front housing 14 fixed to the front end surface of the center housing 12 via a valve plate 13 , and a center housing 12 .
and a rear housing 15 which is joined and fixed to the rear side end surface of the rear housing 15. A rotary drive shaft 16 is supported at the center of the housings 12, 14, and 15 by a front radial bearing 17 and a rear radial bearing 19 engaged with a support plate 18 fitted on the inner surface of the rear housing 15. has been done. A cylinder block 12b having a cylinder bore 12a formed parallel to the rotary drive shaft 16 is integrally formed in the center housing 12. Working pistons 20 are fitted into these cylinder bores 12a so as to be able to reciprocate in the front and rear directions, and each piston 20 is anchored to a swash plate 22 by a piston rod 21. A rotary support body 23 is mounted on the back surface of the swash plate 22 so as to be relatively rotatable by means of a radial bearing 24 and a thrust bearing 25. The rotation of the swash plate 22 is restricted by a guide rod 26 supported and fixed to the center housing 12 and rear housing 15. A sleeve 27 is fitted onto the rotary drive shaft 16 so as to be slidable back and forth, and the sleeve 27 and the rotary support 23 are connected by a connecting pin 28. Further, a support plate 30 is integrally formed at the rear end of the rotary drive shaft 16, and a thrust bearing 31 is interposed between the support plate 30 and the support plate 18. A support arm 32 is integrally formed to protrude from the support plate 30, and the support arm 32 and the rotation support body 23 are connected by a support shaft 33. Further, the support arm 32 is formed with a long hole 32a for guiding the support shaft 33, and the support arm 32 is formed with a long hole 32a for guiding the support shaft 33. The tilting movement is allowed.

A piston accommodating portion 34 is integrally formed on the back surface of the rear housing 15, and a control piston 35 is accommodated in the accommodating portion 34 so as to be able to reciprocate.The control piston 35 and the sleeve 27 are connected to each other. They are connected by a rod 36 and a connecting pin 37. When the discharged refrigerant gas is supplied to the capacity control pressure chamber 38 formed on the rear side of the control piston 35, the control piston 35 is moved forward, and as a result, the sleeve 27 is moved through the connecting rod 36 and the connecting pin 37. is moved forward, the inclination angles of the swash plate 22 and the rotary support 23 are adjusted, and the working piston 20
The stroke of the pump is adjusted, and the discharge volume is adjusted. or,
The activation control pressure chamber 39 on the left side of the control piston 35 communicates with a crank chamber 40 in the center housing 12 through a small gap between the rear housing 15 and the support plate 18 . Further, the control piston 35 is always biased to the left by the biasing spring 41, that is, in a direction that reduces the discharge volume.

A suction chamber 42 and a discharge chamber 43 are defined between the valve plate 13 and the front housing 14, and the suction chamber 42 is communicated with a crank chamber 40 through a suction passage 44 formed in the cylinder block 12a. There is. Further, the valve plate 13 is formed with a suction hole 45 having a suction valve and a discharge hole 46 having a discharge valve. The center housing 12 is provided with the suction flange 47, and the front housing 14 is provided with the discharge flange 48.

Next, a control valve that adjusts the discharge capacity of the compressor based on fluctuations in the suction pressure within the crank chamber 40 will be described. A housing space 51 is formed in one side of the housing 11, and a control valve 52 is housed in the space. This control valve 52 is provided in the middle of a communication passage 53 that communicates the discharge chamber 43 and the capacity control pressure chamber 38. A spherical valve body 55 is accommodated in the valve body 54 of the control valve 52 in correspondence with the valve hole 56, and the valve body 55 is fitted with a spring receiver 57.
The valve hole 56 is normally biased by a spring 58 in a direction to close the valve hole 56. A rod receiver 5 is attached to the spherical valve body 55.
9 is attached to the rod receiver 59, and the actuating rod 6 is attached to the rod receiver 59.
One end of the actuating rod 60 is engaged, and the other end of the actuating rod 60 is in contact with a diaphragm 62 via a rod receiver 61. Further, the pilot pressure chamber 63 formed on the left side of the diaphragm 62 and the crank chamber 40 are connected to a communication passage 64.
It is communicated by. A stopper 66, a small ball 67, a spring receiver 68, and a spring 69 are interposed in the sealed space 65 on the right side of the diaphragm 62. A spring 70, which is weaker than the spring 69, is interposed within the pilot pressure chamber 63 so as to bias the rod receiver 61 toward the diaphragm 62. Then, when the compressor is stopped and the discharge pressure Pd and the suction pressure Ps are equal, the operating rod 60 is moved toward the spherical valve body 55 by the biasing force of the spring 69, as shown in FIG.
is pressed and held in the open position.

A conduit 71 communicating with an activation control pressure chamber 39 provided within the piston accommodating portion 34 is connected to the discharge conduit 2 between the discharge flange 48 and the condenser 3 . A pressure accumulation tank 72 is connected in the middle of this pipe 71, and a first on-off valve 73 and a second on-off valve 73 are connected before and after the pressure accumulation tank 72.
An on-off valve 74 is connected. Both on-off valves 73, 74
is connected to a control device 75, and is selectively opened and closed by an operation signal from the control device 75 when the compressor 1 is started. When the first on-off valve 73 is opened while the second on-off valve 74 is closed, the refrigerant gas discharged from the discharge pipe 2 is stored in the pressure accumulator tank 72. Further, the second on-off valve 74 is switched to the first on-off valve by an operation signal from the control device 75 when the compressor is started.
The on-off valve 73 is opened in the closed state, and the pressure accumulator tank 7
The discharged refrigerant gas stored in the refrigerant 2 is supplied into the startup control pressure chamber 39 to move the control piston 35 from the zero capacity position shown in FIG. 1 to the large capacity position shown in FIG.

Next, the operation of the variable capacity compressor constructed as described above will be explained. Now, when the compressor 1 is in a stopped state, as shown in FIG.
Since the suction pressures Ps of the two are equal and the control piston 35 is biased and held by the biasing spring 41 to keep the swash plate 22 and the rotary support 23 at the zero capacity position, the rotary drive shaft 16 of the compressor is rotated by the power of the engine. No compression is performed even if

In this state, switch (
(not shown), the second on-off valve 74 is opened in response to an operation signal from the control device 75, and the discharged refrigerant gas in the pressure storage tank 72 is supplied to the startup control pressure chamber 39 via the pipe 71. Piston 35 is moved to the right in FIG. As a result, the rotation support body 23 and the swash plate 22 are connected to the support shaft 3.
3, the working piston 20 makes a working stroke, and the compression operation begins. The second opening/closing valve 74 is closed when the swash plate 22 is operated to a predetermined angle, and when the compression operation continues and the pressure of the discharged refrigerant gas increases, the second opening/closing valve 74 is opened/closed by an operation signal from the control device 75. The valve 73 is opened, and the discharged refrigerant gas in the discharge chamber 43 is stored in the pressure accumulation tank 72 via the pipe line 2. The on-off valve 73 is closed by an operation signal from the control device 75 before the compressor is stopped. At this time, the pressure inside the pressure storage tank 72 is detected, and when the pressure exceeds a predetermined value, the on-off valve 73 is closed. You may also do so.

While the compressor is in operation, the discharge capacity of the compressor is automatically adjusted according to the cooling load by the control operation of the control valve 52. That is, the temperature inside the vehicle increases, the cooling load increases, and therefore the suction pressure Ps in the crank chamber 40 increases.
becomes higher, the diaphragm 62 is operated and the spherical valve body 55 is moved in the closing direction by the actuating rod 60, so the amount of discharged refrigerant gas supplied from the discharge chamber 43 to the capacity control pressure chamber 38 decreases, and therefore The control piston 35 is moved to the right to increase the angle of inclination of the swash plate 22 and increase the capacity.

On the other hand, when the temperature in the vehicle compartment decreases and the cooling load decreases, the suction pressure Ps in the crank chamber 40 decreases, so the actuating rod 60 is moved leftward by the diaphragm 62 and the spherical valve body 55 is operated in the opening direction,
Therefore, the discharged refrigerant gas is supplied from the discharge chamber 43 to the capacity control pressure chamber 38, and the control piston 35 is moved in the direction of decreasing the capacity.

Furthermore, during continuous operation, if the discharge capacity of the compressor decreases too much and the discharge pressure Pd and suction pressure Ps become almost the same, the capacity of the compressor cannot be controlled; At the same time, the second on-off valve 74 is opened, the discharged refrigerant gas is supplied to the activation control pressure chamber 39, the discharge capacity is increased, and proper compression operation is restored. moreover,
When the operation of the compressor is stopped, the valve body 55 of the control valve 52 is opened and the refrigerant gas in the discharge chamber 43 is supplied to the capacity control pressure chamber 38 through the communication path 53, so that the control piston 35
is moved to the left, and the swash plate 22 is moved and held at the zero capacity position. At this time, the control piston 35 is also pressed by the elasticity of the biasing spring 41 and is stably held at the zero capacity position.

Now, in the embodiment of the present invention, since the swash plate 22 can be held at the zero capacity position when the compressor is stopped, the starting shock can be greatly alleviated, and the rotational drive shaft 16 Even when the compressor is rotated, no compression operation is performed, making it possible to eliminate the need for a drive clutch for the compressor. Further, it is possible to control the capacity in a small capacity range of about 10% from the zero capacity of the compressor, and it is also possible to prevent frosting of the evaporator during low cooling load operation.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the first on-off valve 73 may be a check valve (not shown), or it may be embodied in a dual-cylinder swash plate compressor. You may change and embody it as you like.

[0022]

[Effects of the Invention] As detailed above, the present invention can reduce the discharge capacity of the compressor to 0%, and as a result, the shock of starting the compressor can be significantly alleviated, and the clutch for starting the compressor can be reduced to 0%. It can also be omitted, and has the excellent effect of enabling capacity control in a small capacity range and preventing frosting of the evaporator during low cooling load operation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a zero capacity state of a compressor.

FIG. 2 is a sectional view showing the maximum capacity state of the compressor.

FIG. 3 is a schematic circuit diagram of a cooling device embodying the present invention.

[Explanation of symbols]

1 Variable capacity compressor, 2 Discharge pipe line, 11 Housing, 16 Rotation drive shaft, 20 Working piston, 22 Swash plate, 23 Rotation support, 32 Support arm, 33 Support shaft, 35 Control piston, 38 Capacity control pressure chamber , 39 startup control pressure chamber, 40 crank chamber, 41 biasing spring, 42 suction chamber, 43 discharge chamber, 52 control valve, 53 communication passage, 64 communication passage,
71 pipe line, 72 pressure accumulation tank, 73 first on-off valve, 74 second on-off valve

Claims (1)

[Claims] 1. A housing having a plurality of cylinder bores arranged around a rotational drive shaft, an actuating piston slidably fitted in each cylinder bore, and connected to each actuating piston via a piston rod. a swash plate that supports the swash plate, a rotary support body that supports the swash plate, is swingable around the axis of a support shaft perpendicular to the axis of the rotary drive shaft, and is connected to the rotary drive shaft; and the rotary support body. and a control piston that is connected to the rotating support and moves in accordance with the pressure of the capacity control pressure chamber in order to adjust the operating stroke of the operating piston by changing the inclination angle around the support shaft axis of the swash plate. , a capacity control valve interposed between the suction chamber and discharge chamber of the compressor and the capacity control pressure chamber to control the discharge capacity of the variable capacity compressor according to the suction pressure; a pressure accumulator which communicates with the discharge chamber of the machine via a pipe line and which hermetically holds the discharged refrigerant gas; an activation control pressure chamber provided on the opposite side of the capacity control pressure chamber of the control piston; and the pressure accumulator; an on-off valve connected to a conduit between the discharge chamber and the pressure accumulation chamber, and a valve provided in the conduit between the discharge chamber and the pressure accumulation chamber of the compressor, which allows discharged refrigerant gas to move into the pressure accumulation chamber and prevents backflow. and a control device that controls opening and closing of the on-off valve based on an operating signal of the compressor.