JPH0355827Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The invention is used for automotive cooling cycles,
This invention relates to an improvement of a variable capacity swash plate type compressor capable of changing the internal volume of a compression chamber.

(Prior Art) As shown in FIG. 4, a cooling cycle 1 used in a general automobile air conditioner is driven by an engine (not shown) via a belt, a pulley 2, and a magnetic clutch 2a. A compressor 3 that converts the gaseous refrigerant that has been adiabatically compressed to a high temperature pressure by the compressor 3 into a low temperature and high pressure liquid refrigerant by exchanging heat with external air, and a condenser 4 that temporarily stores this liquid refrigerant and converts it into a refrigerant. A liquid tank 5 that removes moisture and dust inside, an expansion valve 6 that squeezes and expands this liquid refrigerant to form a low-pressure mist refrigerant, and vaporizes this low-pressure mist refrigerant to cool the air blown into the vehicle interior. It has an evaporator 7.

As the compressor 3 used in such a cooling cycle 1, a swash plate type compressor having a structure shown in Japanese Patent Application Laid-Open No. 158382/1982 has recently been proposed. In this swash plate type compressor, the internal volume of the compression chamber in the cylinder is changed in accordance with the suction pressure of the compressor, thereby changing the discharge amount of the compressor, so that the suction pressure of the compressor remains constant.

When the suction pressure of the compressor 3 shown in FIG. 4 becomes constant, the refrigerant pressure at the outlet of the evaporator 7 (that is, the evaporation pressure of the refrigerant in the evaporator 7) becomes constant to some extent. Therefore, when the heat load becomes small, for example when the outside air temperature is low and it is desired to remove the temperature using the evaporator 7, the expansion valve 6 which tries to keep the amount of superheat at the outlet of the evaporator 7 constant is activated. This is convenient because it is possible to avoid freezing of the evaporator at low loads, which occurs when the refrigerant is throttled too much in order to achieve low cooling performance, lowering the evaporation pressure of the refrigerant in the evaporator 7, and causing the condensed water in the evaporator 7 to freeze.

FIGS. 5 to 7 show the structure of a swash plate compressor in which the internal volume of the compression chamber in the cylinder is changed in accordance with the suction pressure of the compressor, so that the suction pressure is kept constant as a result.

As shown in the figure, the variable capacity swash plate type compressor 3 has a drive shaft 11 that is rotationally driven by an engine via a belt, a pulley 2, and a magnetic clutch 2a. A drive rod 11a is fixed to the drive shaft 11 in a direction perpendicular to the shaft 11, and is adapted to rotate together with the drive shaft 11 within the clutch chamber 12. A drive swash plate 13 is connected to the drive rod 11a at an angle with respect to the drive shaft 11 with the pin 11b as a fulcrum, and the rotational force of the drive shaft 11 is transferred to the pin 11.
The signal is transmitted to the drive swash plate 13 via b. This drive swash plate 13 has a thrust bearing 14.
A non-rotating wobble plate 16 is slidably connected via a radial bearing portion 15. The radial bearing portion 15 is formed on the inner peripheral side of the wobble plate 16, and its thrust direction movement is caused by the thrust washer 2.
0 and Natsupring 21.

The wobble plate 16 is connected to a shoe 19 that is slidably connected to a guide pin 18 fixed to a casing 17, and the shoe 19 prevents rotation and guides movement in the direction of the drive shaft 11. It is becoming more and more like this. This wobble board 1
Pistons 23 are connected to the fifth and sixth pistons 23 at approximately equal intervals in the circumferential direction through a plurality of rods 22, and as the drive swash plate rotates with the rotation of the drive shaft 11, the non-rotatable wobble plate 16 As shown in FIG. 6, the piston 23 swings and reciprocates.

This piston 23 is mounted in a cylinder 25 formed in a cylinder block 24. Inside the cylinder 25, a compression chamber 2 is provided in front of the piston 23.
6 is formed, and the rear surface of the piston 23 communicates with the crank chamber 12.

A suction port 27 and a discharge port 28 are formed in the compression chamber 26 . This suction port 27 is connected to the suction port 2 to which the refrigerant from the evaporator 7 shown in FIG.
9 through a valve (not shown). This suction port 29 communicates with a suction side pressure chamber 32 via a communication passage 31 formed in the head 30.
Further, the discharge port 28 communicates with a discharge port 33 that communicates with a pipe for feeding refrigerant into the condenser 4 shown in FIG. This discharge port 33 communicates with a discharge side pressure chamber 35 .

In the suction side pressure chamber 32, a first control valve 36 is held by a bellows part 37, and the bellows part moves up and down according to the pressure inside the suction side pressure chamber 32 to control the opening degree of the suction side communication port 41. It's starting to adjust.
Further, a second control valve 39 is connected to the first control valve 36 via a rod 38, and the two control valves operate in conjunction with each other. This second control valve 39
is provided in the discharge side pressure chamber 35 and is adapted to adjust the opening degree of the discharge side communication port 40.

These first and second control valves 36 and 39 are controlled by a bellows portion 37 that moves up and down according to the pressure inside the suction side pressure chamber 32, and when the pressure inside the suction side pressure chamber 32 becomes high, the suction side communication port 41 The opening degree of the discharge side communication port 40 is increased, and as the opening degree becomes lower, the opening degree of the discharge side communication port 40 is increased. Therefore, when the heat load in the cooling cycle is small, the pressure in the suction side pressure chamber 32 becomes low, the bellows part 37 extends upward, the opening degree of the discharge side communication port 40 is increased, and the crank chamber 12 to increase its internal pressure. Therefore, the pressure difference between the front and rear of the piston 23 during the suction process (see FIG. 6) increases, and as shown in FIG. acts. Therefore, the reciprocating stroke of the piston 23 becomes shorter, the internal volume of the compression chamber 26 decreases,
The flow rate of refrigerant circulating within the cooling cycle decreases, resulting in an appropriate flow rate of refrigerant corresponding to the low heat load, so the suction pressure of the compressor gradually increases, and as a result, the suction pressure is kept constant.

Further, when the heat load in the cooling cycle is large, the pressure in the suction side pressure chamber 32 increases,
The bellows part 37 moves downward, and the suction side communication port 41
Since the opening degree of the crank chamber 12 is increased and suction pressure is introduced into the crank chamber 12, its internal pressure becomes approximately equal to the suction pressure. Therefore, the pressure difference before and after the piston 23 during the suction process (see Figure 6) is almost eliminated.
As shown in FIGS. 5 and 6, the wobble plate 16 and the drive swash plate 13 can be tilted to the maximum with respect to the drive shaft 11, and the reciprocating stroke of the piston 23 becomes longer. Therefore, the internal volume of the compression chamber 26 increases, and the flow rate of refrigerant circulating within the cooling cycle increases, resulting in an appropriate flow rate of refrigerant corresponding to the high heat load, so the suction pressure of the compressor gradually decreases.
As a result, a constant suction pressure is maintained.

(Problem to be solved by the invention) Capacity control in such a variable capacity swash plate compressor is effective only within a predetermined capacity control range, as shown in Figure 3, and is not effective in other ranges. I couldn't go to

In particular, during low heat loads outside the capacity control range, the pressure Pc in the crank chamber 12 suddenly becomes equal to the compressor discharge pressure Po, as shown by the dotted line in FIG. The pressure difference between the For this reason, the seventh
As shown in the figure, the wobble plate 16 and the drive swash plate 1
3 rises to the maximum angle with respect to the main shaft 11,
Furthermore, since a moment acts in the direction of raising the wobble plate 16, an abnormal force acts in the direction of shearing the thrust washer 20 and the snap spring 21. Such an abnormal force is not preferable because it not only accelerates fatigue of the thrust washer 20 and the snap spring 21 but also causes uneven wear of the radial bearing portion 15.

The present invention was developed in view of these circumstances, and aims to reduce the abnormal force that acts on the sliding part between the wobble plate and the drive swash plate during low loads when effective capacity control cannot be performed. The purpose of the present invention is to provide a durable variable capacity swash plate compressor.

(Means for Solving the Problems) The present invention for achieving the above object includes a drive swash plate connected to the drive shaft so as to have a variable inclination angle, and a drive swash plate slidably connected to the drive swash plate. , a non-rotating wobble plate to which a piston that can reciprocate in the cylinder in the direction of the drive shaft is connected, and an internal pressure of a crank chamber housing the drive swash plate and the wobble plate is formed on the front surface of the piston. In the variable capacity swash plate type compressor, the internal volume of the compression chamber is changed by changing the inclination angle of the wobble plate according to a change in the differential pressure between the internal pressure of the compression chamber and the internal pressure of the compression chamber. A suction pressure communication port and a discharge pressure communication port for introducing compressor discharge pressure are formed, and both of these communication ports and the crank chamber are communicated through a communication passage, and the suction pressure communication port and the discharge pressure communication port are connected to each other by a communication passage. A control valve whose opening degree is controlled by the compressor suction pressure is provided for each of these communication ports, a bypass passage communicating with the compressor suction side is formed in the middle of the communication passage communicating the suction pressure communication port and the crank chamber, and further A bypass valve is provided to release the internal pressure to the compressor suction side when the internal pressure of the crank chamber exceeds a predetermined value.

(effect) Next, the operation of the present invention will be explained.

In the present invention, when the pressure in the crank chamber exceeds a predetermined pressure during low load outside the capacity control range, the bypass valve opens to lower the pressure in the crank chamber. Therefore, the abnormal force that occurs on the sliding portion between the wobble plate and the driving swash plate due to the increase in pressure within the crank chamber is no longer applied.

(Example) Examples of the present invention will be described below.

1 is a schematic cross-sectional view showing a piston in the blowing process of a variable capacity swash plate compressor according to an embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of the same embodiment when the crank chamber pressure changes; FIG. 3 is a graph showing the operation of the present invention, and members common to those shown in FIGS. 5 to 7 are denoted by the same reference numerals, and some explanations thereof will be omitted.

The variable capacity swash plate type compressor 50 shown in FIGS. 1 and 2 is installed between the evaporator 7 and the condenser 4 in the automotive cooling cycle 1 shown in FIG. It functions to adiabatically compress the gaseous refrigerant that has been cooled and vaporized to a high temperature and high pressure, and send it to the condenser 4.

As shown in FIGS. 1 and 2, this variable capacity swash plate type compressor 50 has a drive shaft 11 connected via a magnet 2a to a pulley 2 driven by an engine. A drive swash plate 13 is connected to the drive shaft 11 within the crank chamber 12 via a drive rod 11a and a pin 11b. Therefore, the drive swash plate 13 has a variable inclination angle with respect to the drive shaft 11 using the pin 11b as a fulcrum, and
It is designed to rotate together with the drive shaft 11.

The drive swash plate 13 is equipped with a thrust bearing 1.
4 and a radial bearing portion 15, a non-rotating wobble plate 16 is slidably connected. The radial bearing portion 15 is formed on the inner peripheral side of the wobble plate 16, and its thrust direction movement is caused by the thrust washer 2.
0 and a snap spring 21.

The wobble plate 16 has a shoe 19 slidably connected to a guide pin 18 fixed to a casing 17, and this shoe 19 prevents rotation and movement in the direction of the drive shaft 11. It's starting to be guided. Pistons 23 are connected to the wobble plate 16 via a plurality of rods 22 at approximately equal intervals in the circumferential direction.
The rotation of the drive swash plate 13 with the rotation of the drive shaft 11 causes the non-rotating wobble plate 16 to swing, and the piston 2
3 is designed to move back and forth.

The piston 23 is installed in a cylinder 25 formed in a cylinder block 24, and a compression chamber 26 is formed in the front surface of the piston 23 in the cylinder 25, and the rear surface of the piston 23 communicates with the crank chamber 1. There is.

A suction port 27 and a discharge port 28 are formed in the compression chamber 26 . This suction port 27 communicates with a suction port 29 through which refrigerant from the evaporator 7 shown in FIG. 4 is introduced via a valve (not shown). This suction port 29 is formed in the head 30 and communicates with a suction side compression chamber 32 via a communication passage 31.

Further, the discharge port 28 communicates via a discharge valve 34 with a discharge port 33 which communicates with a pipe for feeding refrigerant into the condenser 4 shown in FIG.
This discharge port 33 communicates with a discharge side pressure chamber 35 .

In the suction side pressure chamber 32, a first control valve 36 is held by a bellows part 37, and the bellows part 37 moves up and down according to the pressure inside the suction side pressure chamber 32, thereby controlling the opening degree of the suction side communication port 41. It's starting to adjust. Further, a second control valve 39 is connected to the first control valve 36 via a rod 38, and both operate in conjunction with each other. This second control valve 39 is provided within the discharge side pressure chamber 35 and is configured to adjust the opening degree of the discharge side communication port 40.

These first and second control valves 36 and 39 are controlled by a bellows portion 37 that moves up and down according to the pressure inside the suction side pressure chamber 32, and when the pressure inside the suction side pressure chamber 32 becomes high, the suction side communication port 41 The opening degree of the discharge side communication port 40 is increased, and as the opening degree becomes lower, the opening degree of the discharge side communication port 40 is increased.

In particular, in this embodiment, a bypass passage 53 heading toward the suction side pressure chamber 32 is formed in the middle of the communication passage 52 between the suction pressure communication port 41 and the crank chamber 12, and a bypass valve 54 is installed in this bypass passage 53. There is. The bypass valve 54 includes a ball valve 55 and a spring 56 that presses the ball valve 55 in a direction to close the bypass path 53. This ball valve 55 is connected to the crank chamber 1 through a communication passage 52.
When the internal pressure of the crank chamber 12 exceeds a predetermined pressure, the bypass passage 53 is opened.

Next, the operation of the variable capacity swash plate compressor having such a configuration will be explained.

During low heat loads outside the capacity control region shown in FIG. 3, the compressor suction pressure Ps decreases significantly.
Therefore, as shown in FIG. 2, the bellows 37 extends upward, the first control valve 36 completely closes the suction side communication port 41, and the second control valve 39 closes the discharge side communication port 40 to the maximum. Open to the limit. As a result, the internal pressure of the crank chamber 12 gradually increases, creating a large pressure difference before and after the piston 23 which is in the suction stroke, and as shown in FIG. Make it stand up as much as possible against 11. When the pressure inside the crank chamber 12 further increases, an abnormal force is generated in the radial bearing portion 15, which is the sliding portion between the wobble plate 16 and the drive swash plate 13. The bypass valve 54 opens the bypass passage 53 and releases the pressure within the crank chamber 12 to the suction side pressure chamber 32.

Changes in the internal pressure Pc of the crank chamber 12 at low loads outside the capacity control range are shown by the chain double-dashed line in FIG.

(Effects of the invention) As explained above, according to the invention, a bypass valve is provided in the suction side communication path for regulating the pressure in the crank chamber to prevent the pressure in the crank chamber from becoming abnormally high. When the load is low and control cannot be performed effectively, no abnormal force is applied to the sliding portion between the quackle plate and the driving swash plate, which has the excellent effect of increasing the durability of the compressor.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a piston in the discharge process of a variable capacity swash plate compressor according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of the same embodiment when the crank chamber pressure changes; FIG. 3 is a graph showing the action of the present invention, FIG. 4 is a schematic diagram showing a general automobile cooling cycle, and FIG. 5 is a schematic sectional view showing a piston in the discharge process of a conventional variable capacity swash plate compressor. , FIG. 6 is a schematic sectional view showing the piston of the same compressor in the suction process, and FIG. 7 is a schematic sectional view of the same compressor when the crank chamber pressure changes. 11... Drive shaft, 12... Crank chamber, 13...
...Drive swash plate, 15...Radial bearing section, 16...
Wobble board, 20... Thrust washer, 21...
...Snat spring, 23...Piston, 25...
Cylinder, 26...Compression chamber, 32...Suction side pressure chamber, 35...Discharge side pressure chamber, 36...First control valve, 39...Second control valve, 40...Discharge side communication port, 41... ...Suction side communication port, 52...Communication path, 5
4...Bypass valve.

Claims (1)

[Claims for Utility Model Registration] A drive swash plate 13 connected to the drive shaft 11 in a variable inclination angle, and a cylinder 25 slidably connected to the drive swash plate 13 in the direction of the drive shaft 11.
A non-rotating wobble plate 16 is connected with a piston 23 that can reciprocate within the driving swash plate 13.
Due to a change in the differential pressure between the internal pressure of the crank chamber 12 housing the and wobble plate 16 and the internal pressure of the compression chamber 26 formed on the front surface of the piston 23,
In the variable capacity swash plate type compressor that changes the internal volume of the compression chamber 26 by changing the inclination angle of the wobble plate 16, the compressor suction pressure is applied to the crank chamber 12.
A suction pressure communication port 41 that introduces Ps and a discharge pressure communication port 40 that introduces compressor discharge pressure PO are formed, and these communication ports 40, 41 and the crank chamber 12 are connected through communication passages 52, 60. A control valve 3 that communicates with the suction pressure communication port 41 and the discharge pressure communication port 40 to control the opening degree of the suction pressure communication port 41 and the discharge pressure communication port 40 using the compressor suction pressure Ps.
6 and 39 are provided in both of these communication ports 40 and 41, respectively, and a compressor suction side 3 is provided in the middle of a communication passage 52 that communicates the suction pressure communication port 41 and the crank chamber 12.
A bypass path 53 communicating with 2 is formed, and further,
When the internal pressure of the crank chamber 12 exceeds a predetermined value, the internal pressure is transferred to the compressor suction side 3.
2. A variable capacity swash plate type compressor, characterized in that a bypass valve 54 is provided to provide relief to the air.