JPS61215468A - Variable capacity compressor - Google Patents

Abstract

PURPOSE:To prevent excessive increase of pressure in crank chamber upon abrupt acceleration of vehicle by coupling between a suction chamber for varying the inclination angle of a rolling inclination board for varying the capacity through the differential pressure and the crank chamber through an air supply path arranged with a gate valve. CONSTITUTION:A variable capacity compressor suitable for vehicle air conditioner has a rotary member 17 rotatable through a drive shaft 10 and upon inclination of a rolling inclination board 19 coupled through a pin 18 with said rotary member 17, the piston 13 is reciprocated through a piston rod 14. In accordance to the differential pressure between the suction chamber 4 and the crank chamber 9, the piston stroke will vary to vary the inclination angle of said board 19 thus to control the compression capacity. Here, an air supply path (23-27) 22 communicating between the delivery chamber 6 and the crank chamber 9 is formed and a gate valve 28 is arranged in the way. Said valve 28 is controlled to close upon exceeding of the pressure in the crank chamber over a setting level.

Description

[Detailed Description of the Invention] Object of the Invention (Field of Industrial Application) The present invention relates to a variable capacity compressor used for vehicle air conditioning, etc., and particularly includes a suction chamber, a discharge chamber, and a crank chamber.
This relates to a variable angle oscillating inclined plate type compressor in which the piston stroke is changed according to the differential pressure between the suction pressure and the crank chamber pressure, and the inclination of the oscillating inclined plate is changed to control the compression capacity. It is.

(Prior Art) Conventionally, as this type of variable capacity compressor, one having a configuration as shown in, for example, Japanese Patent Application Laid-open No. 158382/1982 is known. This compressor is equipped with a bellows in the suction chamber to detect suction pressure, and when the suction pressure drops to a predetermined pressure due to a drop in cooling load or high speed rotation, the balance between the suction pressure and atmospheric pressure changes. The expansion of the bellows along with this actuates the valve mechanism, which closes the communication path between the crank chamber and the suction chamber, and opens the communication path between the discharge chamber and the crank chamber, increasing the crank chamber pressure. As a result, the differential pressure between the crank chamber pressure and the suction pressure increases, the stroke of the piston decreases, and the angle of inclination of the rocking inclined plate for reciprocating the piston decreases, reducing the predetermined suction pressure. It is designed to prevent the drop in capacity from exceeding the limit and at the same time reduce the capacity.

(Problem to be Solved by the Invention) However, in this conventional variable displacement compressor, the valve mechanism is opened and closed by detecting changes in suction pressure using a bellows. As a result, when the suction pressure temporarily decreases, the bellows acts sensitively and activates the valve mechanism, and during this sudden acceleration, the piston is activated only by the decrease in suction pressure without increasing the crank chamber pressure. The stroke is automatically reduced,
Despite the transition to small-capacity operation, high-pressure discharge gas is sent into the crank chamber as the valve mechanism operates, and the crank chamber pressure is excessively increased.

Therefore, even if the rotation speed decreases after the sudden acceleration operation described above ends, the pressure in the suction chamber increases due to this decrease in rotation speed and the lack of capacity due to the small capacity operation, and the pressure between the suction chamber and the crank chamber increases. If the difference is small, the excessively high pressure in the crank chamber will drop only gradually, and small-capacity operation will continue with the piston stroke remaining reduced. As a result, the cabin temperature rises, and in order to lower it again to the optimum temperature, the tilt angle of the swinging tilt plate must be returned to the maximum angle.
Not only does it take a long time to return to the optimum temperature, but the pressure in the crank chamber is excessively increased with each sudden acceleration, resulting in an increase in shaft seal surface pressure and a reduction in the durability of the shaft seal mechanism.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned problems, and includes a suction chamber and a discharge chamber, and is capable of controlling the differential pressure between the suction pressure and the crank chamber pressure. In a variable capacity compressor in which the inclination angle of the oscillating tilting body changes accordingly to control the compression capacity, an air supply passage that communicates between the discharge chamber and the crank chamber and the air supply passage are opened and closed. an on-off valve, an air bleed passage that constantly communicates the suction chamber and the crank chamber, and when the pressure in the crank chamber falls below a set value, the on-off valve is operated in response to the pressure, and the intake air is removed. A valve control mechanism is provided for opening the air passage and operating the on-off valve when the air exceeds a set value to close the air supply passage.

(Function) Accordingly, in the present invention, when the compressor is in operation with the on-off valve closing the air supply passage, the refrigerant gas blow-byed from the compression chamber to the crank chamber is returned to the suction chamber via the bleed passage. When the cabin temperature falls, the cooling load becomes small, and the crank chamber pressure falls below the set value as the suction pressure decreases, the valve control mechanism opens the on-off valve and high-pressure gas flows from the discharge chamber to the crank chamber. and increases the crank chamber pressure. When the crank chamber pressure exceeds a set value, the valve control mechanism closes the on-off valve, the air supply passage is closed, and the increase in pressure in the crank chamber is stopped. In this way, the crank chamber pressure always remains approximately at the set value during steady operation. Therefore, the stroke of the piston is controlled by the differential pressure between the crank chamber pressure, which is almost constant, and the suction pressure, which varies depending on changes in the cooling load, etc., and the compression capacity is controlled.

On the other hand, even when the suction pressure temporarily decreases during sudden acceleration, the crank chamber pressure remains almost at the set value, so the piston stroke is suppressed by the increase in differential pressure between the crank chamber pressure and the suction pressure. , the inclination angle of the swinging inclined plate becomes temporarily smaller, and the compression capacity decreases. When the sudden acceleration is stopped and the suction pressure increases, the differential pressure between the two chambers also decreases, so that the swinging inclined plate quickly returns to its original angle of inclination.

(Embodiment) Hereinafter, the configuration of an embodiment embodying the present invention will be described with reference to the drawings.

Now, this embodiment is a concrete example of a variable capacity compressor of a variable angle swinging inclined plate type used in a vehicle air conditioner, and as shown in FIG. A rear housing 3 is joined and fixed via the valve plate 2 by appropriate tightening means. An annular suction chamber 4 is defined at the outer circumference of the rear housing 3, and a discharge chamber 6 is defined at the center of the rear housing 3. It is connected to the. A front housing 8 is fixedly connected to the left end surface of the cylinder block 1, and a crank chamber 9 is formed inside the front housing 8. A drive shaft 10 is rotatably supported by the cylinder block 1 and the front housing 8 via a pair of bearings 11 and a shaft seal mechanism 47.

The cylinder block 1 has 5 holes extending through the cylinder block 1 between both ends thereof.
Cylinder chambers 12 (see FIG. 3) are formed parallel to the drive shaft 10. Inside each cylinder chamber 12 is a piston 1.
3 is attached so as to be able to reciprocate and slide, and a piston rod 14 is articulated to its left end surface. Each of the valve plates 2 is formed with a suction valve mechanism 15 for introducing refrigerant gas from the suction chamber 4 into the compression chamber of each cylinder chamber 12 .

Similarly, the valve plate 2 is provided with a discharge valve mechanism 1 for guiding the refrigerant gas compressed in the compression chamber of each cylinder chamber 12 to the discharge chamber 6.
6 is provided.

A rotary body 17 is fitted and fixed on the drive shaft IO, and a swinging inclined plate 19 is tiltably connected to the rotary body 17 by a connecting pin 18, and rotated by a guide rod 20 horizontally suspended in a fixed position. regulated. Further, the left end portions of the respective piston rods 14 are connected to the swinging inclined plate 19, and when the rotating body 17 is rotated by the rotation of the drive shaft 10 and the swinging inclined plate 19 is tilted, the piston rods are connected to each other. The piston 13 is reciprocated via the piston 14. Then, the piston stroke changes according to the differential pressure between the suction pressure in the suction chamber 4 and the crank chamber pressure in the crank chamber 9, and the inclination angle of the rocking inclined plate 19 changes, thereby controlling the compression capacity. ing.

The configuration described above is similar to that of a conventional variable capacity compressor.

Next, referring to the main part of the present invention, a bulging portion 21 is integrally formed at the lower part of a partition wall in the rear housing 3 that partitions the discharge chamber 6 and the suction chamber 4. An air supply passage 22 is provided between the two chambers 6 and 9 so as to communicate the discharge chamber 6 with the crank chamber 9. A passage 23 formed to communicate with the lowermost part of the chamber 6, a passage 24 extending in the horizontal direction and formed at the center of the bulge 21 in communication with the passage 23, and a passage 24 formed at the center of the cylinder block 1. a bearing hole 25 for the drive shaft lO, a passage 26 that communicates with the passage 24 and the bearing hole 25 and is formed in the bulge 21, the valve plate 2, and the cylinder block 1, and a bearing in the bearing 11. A gap and a passage 2 formed on the left end surface of the cylinder block 1
7. In the passages constituting this air supply passage 22, the bearing hole 25 and the passages 26 and 27 pass through the cylinder block 1 laterally from the middle of the passage 26 as shown by the two-dot chain line in FIG. An on-off valve 28 for opening and closing the air supply passage 22 is provided at the boundary between the 0 passage 23 and the passage 24, which may have a passage 22A structure, and this on-off valve 28 is formed at the left end of the horizontal passage 24. The valve seat 29 is made up of a valve seat 29, a spherical valve body 30 is arranged so as to be able to move toward and away from the valve seat 29, and a spring 31 urges the spherical valve body 30 in the closing direction to come into contact with the valve seat 29. ing.

The opening/closing valve 2 is provided in the bulging portion 21 of the rear housing 3.
A valve control mechanism 39 for controlling the opening and closing of the valve 8 is incorporated.

To explain this, a housing recess 32 is formed to correspond to the passage 24 and open to the atmosphere, a bellows 33 is stored in the recess 32, and a mounting ring 34 at the base end of the housing recess 32 is formed. It is brought into contact with the inner circumferential surface of the accommodation recess 32 via an O-ring 35, and is held in place by a stop ring 36. Also, the mounting plate 37 at the tip of the bellows 33
An actuating rod 38 is attached to the center of the lateral passageway 24 and is capable of pushing the spherical valve body 30 in the opening direction against the elasticity of the spring 31.

Further, a spring receiver 40 is screwed and fixed to the inner circumferential surface of the mounting ring 34, and a spring 41 is interposed between the mounting plate 37 and the operating rod 38 to urge the operating rod 38 toward the spherical valve body 30. ing. Further, a passage 43 is formed in the spring receiver 40, which communicates the space inside the bellows 33 with the outside air to form an atmospheric chamber 42. A pressure sensitive chamber 44 is defined by the housing recess 32, bellows 33, mounting ring 34, mounting plate 37, etc., and the pressure sensitive chamber 44 and the crank chamber 9 are connected to the cylinder block l, the valve plate 2, and the expansion plate 37. A pressure channel 4 passing through the outlet 21 in the lateral direction
5.

In this embodiment, the pressure in the crank chamber 9 is set at a set value (
For example, when the pressure is greater than 2.5 atmospheres, the pressure sensitive chamber 44
The force that tries to move the operating rod 38 to the valve closing position due to the pressure of
We are trying to close 8. Also, on the contrary, crank chamber 9
When the pressure of the operating rod 3 becomes smaller than the set value, the operating rod 3
The direction of the force acting on the valve 8 is reversed so that the on-off valve 28 is opened.

A bleed passage 46 for communicating the crank chamber 9 and the suction chamber 4 is provided in the cylinder block 1 and the valve plate 2, passing through it in the lateral direction. Refrigerant gas blow-by from the compression chamber into the crank chamber 9 is returned into the suction chamber 4, thereby suppressing an increase in crank chamber pressure.

Next, the operation of the variable capacity compressor configured as described above will be explained.

Now, when this compressor is stopped, the crank chamber pressure in the crank chamber 9 is at a pressure (for example, 4 atm) higher than the set value (for example, 2.5 atm), so the pressure in the crank chamber 9 is higher than the set value (for example, 2.5 atm), so the
), the operating rod 38 is in the valve closed position, and the spherical valve body 30 of the on-off valve 28 is in contact with the valve seat 29 and the air supply passage 22 is closed.
is in a closed state. When the drive shaft 10 is rotated by the power of an engine or the like in this state, the swinging inclined plate 19 is tilted in a rotationally restricted state via the rotating body 17 and the connecting pin 18. As a result, each piston 13 is reciprocated via the piston rod 14, and the suction valve mechanism 15 is moved from the suction chamber 4 to the suction valve mechanism 15.
The refrigerant gas sucked into the compression chamber of the cylinder chamber 12 through the compressor is compressed within the compression chamber, and then is forced into the discharge chamber 6 through the discharge valve mechanism 16 .

On the other hand, refrigerant gas is blow-byed into the crank chamber 9 from the compression chamber of the cylinder chamber 12 through the gap between the inner peripheral surface of the cylinder chamber 12 and the outer peripheral surface of the piston 13; 9 and is returned into the suction chamber 4 via a bleed passage 46 which is always open. In the early stages of starting the compressor, if the temperature inside the vehicle to be cooled is high and the cooling load is large, the crank chamber pressure (for example, 4 atmospheres) is slightly higher than the suction pressure, and the differential pressure is maintained at a predetermined level. The piston 13 is reciprocated at the maximum stroke, and the tilting angle of the swinging inclined plate 19 is maintained at a large angle, and operation with the full compression capacity is performed.

When the compressor is operated in this manner, and the temperature inside the vehicle compartment decreases and the cooling load decreases, the suction pressure decreases, and along with this decrease, the crank chamber pressure also decreases. When the pressure in the crank chamber 9 becomes lower than the set value (2.5 atmospheres), the internal pressure in the pressure sensitive chamber 44 also decreases, the bellows 33 is expanded by the spring 41, and the operating rod 38 presses the spherical valve body 30. Then, the valve body 30 is separated from the valve seat 29, and the air supply passage 22 is opened as shown in FIG. 2(b). Thereby, the discharge gas flows into the crank chamber 9 from the discharge chamber 6 via the air supply passage 22, and the decrease in crank chamber pressure is stopped.

At this time, the gas flowing into the crank chamber 9 from the discharge chamber 6 via the air supply passage 22 is throttled by the narrow gap of the bearing 11, so that the pressure in the crank chamber 9 gradually increases. When the pressure in the crank chamber 9 exceeds a set value due to gas from the air supply passage 22, the operating rod 38 is moved to the valve closing position, and the spherical valve body 30 is brought into contact with the valve seat 29 by the spring 31. The air supply passage 22 is closed, and the pressure increase in the crank chamber 9 is stopped. In this way, the pressure in the crank chamber 9 remains automatically maintained at the set value during steady operation.

In addition, when the cabin temperature decreases and the cooling load further decreases, the suction pressure decreases regardless of the crank chamber pressure, which is maintained at approximately the set pressure as described above, and the difference between the crank chamber pressure and the suction pressure decreases. When the pressure exceeds a predetermined value (for example, 0.5 atmospheres), the stroke of the piston 13 is reduced, the tilt angle of the swinging inclined plate 19 is reduced, and the operation is shifted to a small compression capacity.

In addition, during steady operation, if the engine etc. is rapidly accelerated and the rotational speed of the drive shaft IO suddenly increases, the suction pressure decreases and the differential pressure between the crank chamber pressure and the suction pressure increases, causing the piston to 13 strokes are reduced and the compression capacity is reduced. At this time, the opening/closing valve 2 is not affected by the suction pressure at all, so the pressure in the crank chamber 9 does not increase excessively.After that, the rapid acceleration of the engine is stopped and the rotational speed of the drive shaft 10 is reduced. In this case, the stroke of the piston 13 increases as the suction pressure increases, increasing the compression capacity.

Note that in the present invention, for example, a vacuum chamber (not shown) may be provided in place of the atmospheric chamber 42, or a diaphragm (not shown) may be used in place of the bellows 33.

Effects of the Invention As detailed above, this invention can maintain the crank chamber pressure at almost the set value regardless of the suction pressure during steady operation, and even if sudden acceleration occurs temporarily, the crank chamber pressure can be maintained at almost the set value. The pressure in the chamber is not increased excessively, and therefore the operating time in a state where the shaft seal surface pressure is low is extended, and the durability of the shaft seal mechanism can be improved. Also, during the sudden acceleration mentioned above, the suction pressure decreases, so the differential pressure between the crank chamber pressure and the suction pressure increases (as a result, the stroke of the piston decreases and the capacity decreases, but after this sudden acceleration is completed) When the rotational speed decreases, the crank chamber pressure is held almost constant, so as the suction pressure increases, the differential pressure decreases, and the compression capacity quickly returns to its original state, resulting in rapid acceleration. The quenching shoulder characteristics after completion are improved.

Even if this sudden acceleration is performed at startup, the crank chamber pressure will not be excessively increased (therefore, the compression capacity will return to its original level quickly after the sudden acceleration is completed, and this will improve the cool-down characteristics). effective.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a compressor showing an embodiment embodying the present invention, Fig. 2(a) is an enlarged sectional view showing the valve control mechanism in a closed state, and Fig. 2(b) is an enlarged sectional view showing the valve control mechanism in the closed state. An enlarged sectional view of the state, FIG. 3 is a sectional view taken along the line A--A in FIG. 1. 4... Suction chamber, 6... Discharge chamber, 9... Crank chamber, 19... Rocking inclined plate, 21... Swelling part, 22...
・Air supply passage, 28... Opening/closing valve, 33... Bellows,
37... Mounting plate, 38... Operating rod, 39... Valve control mechanism, 41... Spring, 42... Atmospheric chamber, 44...
・Pressure sensitive chamber, 45...Pressure path, 46...Bleed air path.

Claims (1)

[Scope of Claims] 1. Comprising a suction chamber, a discharge chamber, and a crank chamber, the inclination angle of the oscillating tilting body changes according to the differential pressure between the suction chamber pressure and the crank chamber pressure to control the compression capacity. A variable capacity compressor configured to include: an air supply passage that communicates between the discharge chamber and the crank chamber; an on-off valve that opens and closes the air supply passage; and an air bleed passage that constantly communicates the suction chamber and the crank chamber. and when the pressure in the crank chamber falls below a set value, the on-off valve is operated in response to the pressure to open the air supply passage, and when the pressure in the crank chamber becomes above the set value, the on-off valve is operated. ,
A variable displacement compressor consisting of a valve control mechanism for closing the air supply passage. 2. The on-off valve is composed of a valve seat formed in the air supply passage, a spherical valve body that opens and closes the air supply passage corresponding to the valve seat, and a spring that biases the valve body in the closing direction. A variable capacity compressor according to claim 1. 3. The valve control mechanism includes a bellows that defines an atmospheric chamber and a pressure sensitive chamber that communicates with the crank chamber via a pressure path, and an operating rod that is attached to the bellows and opens and closes the on-off valve. A variable capacity compressor according to claim 1 or 2, comprising: