JPS61286591A - Variable capacity compressor - Google Patents

Abstract

PURPOSE:To keep pressure in the crank chamber of a variable capacity compressor always at a predetermined level for good response and improve the controllability of capacity by letting said pressure control each open/close valve at a passage between the crank chamber and the delivery chamber, and between the crank chamber and the suction chamber. CONSTITUTION:A primary open/close valve 34 is provided at an air feed passage 35 between the crank chamber 7 of a variable capacity compressor used for the airconditioning of vehicles and the like, and the delivery chamber 5 thereof. Also, a secondary open/close valve 39 is provided at a bleed passage 40 between the crank chamber 7 and the suction chamber 4 of said compressor. Both of said valves 34 and 49 are controlled for opening and closing by a single actuating lever 25 through the application of pressure in the crank chamber 7 to a bellows 34. And the opening and closing control is so made that the primary open/close valve 34 opens and the opening of the secondary open/close valve 39 is throttled, when pressure in the crank chamber 7 is equal or below a predetermined level. On the contrary, when said pressure is above the predetermined level, the primary open/close valve 34 closes and the opening of the secondary open/close valve 39 is made wide.

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 more specifically, it is provided with a suction chamber, a discharge chamber, and a crank chamber, Variable displacement compression with a variable angle swinging tilt plate type that controls the compression capacity by changing the stroke of the piston and changing the tilt angle of the swinging tilt plate according to the differential pressure between the crank chamber pressure and the suction pressure. It's about machines.

(Prior Art) The applicant of the present application has recently installed an on-off valve in the air supply road that communicates the discharge chamber and the crank chamber as a variable capacity compressor, and the crank chamber and the suction chamber are kept at a constant opening. Constant communication is provided through the air bleed passage, and when the pressure in the crank chamber falls below the set pressure, the on-off valve is operated in response to that pressure to open the air supply passage, and conversely, when the pressure rises above the set pressure. proposed a system in which the air supply passage is closed to keep the pressure in the crank chamber constant. (Special application 1986-5642
No. 2) (Problems to be Solved by the Invention) However, in this conventional variable capacity compressor, since the bleed passage is always at the same opening (amount of throttling), the following new problem arises. Ta. In other words, for example, when the engine brake is applied when going downhill, when decelerating suddenly to enter a parking area from a highway, or when returning to a constant speed after completing sudden acceleration, the pressure in the intake chamber suddenly increases. When the pressure rises to above the set pressure in the crank chamber and the differential pressure between the two cylinders suddenly changes, the opening degree of the bleed passage is constant, so the pressure in the crank chamber gradually increases as the pressure in the suction chamber increases. As a result, the pressure in the crank chamber cannot be kept constant (at high pressure levels, the differential pressure between the crank chamber and the suction chamber fluctuates (decreases), and the stroke of the piston becomes smaller. There was a problem in that when cooling capacity was required, the system would operate at a small capacity.

Furthermore, in this small capacity operating state, the amount of lubricating oil is small and the amount of gas blow-by from the compression chamber to the crank chamber increases, so the pressure in the crank chamber becomes high. However,
Since the pressure in the crank chamber is constant depending on the opening degree of the bleed passage, the pressure reducing effect of the gas returned to the suction chamber is slow. Therefore, even if the engine brake is released and the compressor returns to constant speed rotation and the suction pressure decreases, it takes time for the crank chamber pressure to decrease to the set pressure, and the transition to full capacity operation is delayed accordingly. There is a problem with delays.

Structure of the Invention (Means for Solving the Problems) The present invention has been made in view of the above-mentioned problems, and includes a suction chamber, a discharge chamber, and a crank chamber. In a variable capacity compressor with a variable-angle oscillating inclined plate that controls compression capacity by changing the piston stroke and changing the inclination angle of the oscillating inclined plate in accordance with the differential pressure between the discharge chamber and An air supply passage communicating with the crank chamber and an air bleed passage communicating the crank chamber and the suction chamber are provided, the air supply passage having a first on-off valve, and the air bleed passage having a second on-off valve. A valve control mechanism that operates in response to changes in crank chamber pressure opens the first on-off valve and opens the second on-off valve when the crank chamber pressure falls below the set pressure. On the other hand, when the pressure in the crank chamber becomes equal to or higher than the set pressure, the first opening/closing valve is closed and the second opening/closing valve is operated in the direction of increasing the opening. ing.

(Function) Therefore, in this invention, when the pressure in the crank chamber becomes lower than the set pressure, the first on-off valve is opened by the valve control mechanism, and high pressure gas flows from the discharge chamber to the crank chamber via the air supply passage. As the pressure in the crank chamber increases, the degree of opening of the second on-off valve becomes smaller, and the pressure in the crank chamber increases faster.

Conversely, when the pressure in the crank chamber exceeds the set pressure,
The first on-off valve is closed by the valve control mechanism, stopping the supply of high-pressure gas from the discharge chamber to the crank chamber, and the opening degree of the second on-off valve is increased to return gas from the crank chamber to the suction chamber. As a result, the crank chamber pressure is quickly returned to the set pressure. In this way,
The pressure in the crank chamber is accurately maintained at the set pressure.

In addition, if the opening degree of the second on-off valve is large and the compressor is operating at full capacity, for example, if the engine brake is activated and the suction pressure suddenly becomes higher than the pressure in the crank chamber, the suction pressure will be removed from the suction chamber. Since gas quickly flows into the crank chamber, fluctuations in the differential pressure between the crank chamber pressure and the suction pressure are reduced, and therefore the reduction in compression capacity is also reduced. Then, when the compressor is returned to steady operation and the suction pressure becomes low, gas is quickly returned from the crank chamber to the suction chamber, the differential pressure is returned to the predetermined value, and full capacity operation is resumed immediately. Will be reinstated.

(Example) The configuration of an example embodying this invention is shown in Figs.
This will be explained according to FIG.

As shown in FIG. 1, a rear housing 3 is fixed to the right end surface of the cylinder block 1 via a valve plate 2.

An annular suction chamber 4 is defined on the outer periphery of the rear housing 3, and a discharge chamber 5 is formed in the center thereof, and is connected to an external cooling circuit through an inlet and a discharge outlet (none of which are shown). It is connected. A front housing 6 is fixedly connected to the left end surface of the cylinder block 1, and a crank chamber 7 is formed inside the front housing 6. A drive shaft 8 is rotatably supported by the cylinder block 1 and the front housing 6.

The cylinder block 1 has a cylinder 6 extending between both ends thereof.
Cylinder chambers 9 (only one shown) are formed parallel to the drive shaft 8 . A piston 10 is mounted in each cylinder chamber 9 so as to be able to slide back and forth, and a piston rod 11 is articulated to the left end surface of the piston 10 . A suction valve mechanism 12 for introducing refrigerant gas from the suction chamber 4 into the compression chamber of each cylinder chamber 9 is formed in each of the valve plates 2 . Similarly, the valve plate 2 is provided with a discharge valve mechanism 13 for guiding the refrigerant gas compressed in the compression chamber of each cylinder chamber 9 to the discharge chamber 5.

A rotary body 14 is fitted and fixed to the drive shaft 8, and a rotary drive plate 16 is tiltable through a connecting pin 15 in a long hole formed in a protrusion 14A projecting from the rotary body 14. It is mounted so as to be rotatable together with the rotating body 14.

A swinging inclined plate 17 is attached to the rotary drive plate 16.
The guide rod 18 is supported so as to be tiltable, and its rotation is regulated by a guide rod 18 horizontally suspended at a fixed position. Further, the left end portions of the piston rods 11 are respectively connected to the swinging inclined plate 17, and when the rotating body 14 is rotated by the rotation of the drive shaft 8 and the swinging inclined plate 17 is tilted, the piston loft is changed. The piston 10 is reciprocated via the piston 11. Then, the piston stroke changes according to the differential pressure between the crank chamber pressure in the crank chamber 7 and the suction pressure in the suction chamber 4, and the inclination angle of the rocking inclined plate 17 changes, so that the compression capacity is controlled. ing.

Next, main parts of the present invention will be explained.

A bulge 19 is integrally formed on the back surface of the rear housing 3, and a control valve 20 constituting a control device for keeping the pressure in the crank chamber substantially constant is housed and fixed therein. This control valve 20 will be explained with reference to FIG. 2. The upper end outer circumference of a cylindrical second case 22 is screwed and fixed inside the lower end of a first case 21 which is a cylindrical shape with a lid and a bottom. A third case 23, which also has a cylindrical shape, is screwed and fixed inside the lower end of the second case 22.

A bellows 24 is housed inside the first case 21, and the upper end of an operating rod 25 that penetrates the second case 22 and extends toward the third case 23 is fixed to the tip of the bellows 24. It is biased downward by a spring 26 housed within the bellows 24.

Inside the bellows 24 is an atmospheric chamber 27 that communicates with the atmosphere.
A pressure sensing chamber 28 for sensing the pressure Pc in the crank chamber 7 is formed between the bellows 24 and the first case 21, and the interspace 28 is connected to the cylinder block 1, rear housing 3 and first case It communicates with the crank chamber 7 through a pressure guiding path 29 formed in 21 . In this embodiment, the first case 21, the bellows 24, the operating rod 25, the spring 26, the atmospheric chamber 27, the pressure sensitive chamber 28, the pressure guide path 29, etc., are connected to the first and second on-off valves 34, 39, which will be described later. A valve control mechanism 30 is configured to perform control.

Inside the third case 23 are a valve chamber 31 , a truncated conical valve body 32 housed in the valve chamber 31 and opened by the operating rod 25 , and a spring 26 of the valve control mechanism 30 .
A first on-off valve 34 is provided which includes a spring 33 that biases the valve body 32 in the closing direction, although the biasing force is slightly weaker than that of the spring 33 .

The first on-off valve 34 is disposed in the middle of an air supply passage 35 that communicates the discharge chamber 5 and the crank chamber 7, and controls the supply of gas from the discharge chamber 4 to the crank chamber 7. There is. Note that a filter 36 is provided on the lower surface of the third case 23 to remove impurities contained in the gas in the air supply passage 35.
is provided.

A second on-off valve 39 consisting of a valve chamber 37 and a valve body 38 integrally formed in the middle part of the operating rod 25 is disposed inside the second case 22, and the second on-off valve 39 is connected to the crank chamber. 7
The flow rate of gas returned from the crank chamber 7 to the suction chamber 4 can be adjusted by controlling the relationship of the second on-off valve 39. That's what I do.

In this embodiment, when the pressure Pc in the crank chamber 7 is greater than the set pressure (for example, 2.7 atmospheres), the pressure in the pressure sensitive chamber 28 becomes greater than the combined force of the spring force of the spring 26 and atmospheric pressure. , the operating rod 25 is pushed upward, closing the first on-off valve 34 and increasing the opening degree of the second on-off valve 39. Conversely, when the pressure in the crank chamber 7 becomes lower than the set pressure, the direction of the force acting on the operating rod 25 is reversed, and the first on-off valve 34 is opened.
Moreover, the opening degree of the second on-off valve 39 is made small.

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

Now, at the beginning of the compressor startup, if the temperature inside the vehicle to be cooled is high and the cooling load is large, the crank chamber pressure Pc (for example, 4 atmospheres) is slightly higher than the suction pressure Ps, and the differential pressure Δp(Pc-Ps) is kept smaller than a predetermined value, the piston 10 is reciprocated at the maximum stroke, and the swinging inclined plate 17 is operated at full compression capacity with a large inclination angle. In this state,
As shown in FIG. 2, the pressure Pc in the crank chamber 7 exceeds the set pressure (2.7 atmospheres) and the pressure in the pressure sensitive chamber 28 increases,
The operating rod 25 is moved upward, the air supply passage 35 is closed by the first on-off valve 34, the supply of gas from the discharge chamber 5 to the crank chamber 7 is stopped, and the opening degree of the second on-off valve 38 is increased. gas moves quickly between the crank chamber and the suction chamber.

Thereafter, when the temperature in the vehicle interior decreases and the cooling load becomes smaller, the suction pressure Ps decreases, and the pressure Pc in the crank chamber 7 also decreases with this decrease. At this time, since the degree of opening of the second on-off valve 39 is large, the pressure in the crank chamber 7 is quickly reduced substantially in synchronization with the reduction in the suction pressure Ps. Therefore, the differential pressure Δp is kept substantially constant, and the full capacity operating state is maintained.

Furthermore, when the temperature inside the vehicle compartment decreases, the cooling load decreases, the crank chamber pressure and suction pressure decrease, and the crank chamber pressure Pc becomes lower than the set pressure (2.7 atm), the internal pressure of the pressure sensitive chamber 28 also decreases. The bellows 24 is extended by the spring 26, and the tip of the operating rod 25 touches the valve body 3 as shown in FIG.
2, and then, as shown in FIG. 4, the valve body 32 is pushed to open the air supply passage 35. As a result, high pressure gas flows into the crank chamber 7 from the discharge chamber 5 via the air supply passage 35, and the decrease in the crank chamber pressure Pc is stopped. Also, in this state, the opening degree of the second on-off valve 39 is reduced by the valve body 38, so the amount of gas returned from the crank chamber 7 to the suction chamber 4 is reduced, and the pressure in the crank chamber 7 reaches the set pressure. He will be returned promptly.

On the contrary, in the state shown in FIG.
The pressure Pc of the high pressure gas from the air supply road 35 (discharge pressure P
When the set pressure is exceeded in step d), the operating rod 25 is moved upward, the air supply passage 35 is closed by the valve body 32 of the first on-off valve 34, and the increase in crank chamber pressure Pc is stopped. At this time, the valve body 38 of the second on-off valve 39 is also connected to the operating rod 25.
As a result, the opening degree of the on-off valve 39 increases, and the pressure Pc in the crank chamber 7 is quickly lowered to the set pressure. In this way, the pressure Pc in the crank chamber 7 is automatically, quickly, and accurately maintained at the set pressure during steady operation.

Further, when the cabin temperature decreases and the cooling load further decreases, the suction pressure P3 decreases regardless of the crank chamber pressure Pc which is maintained at the set pressure as described above, and the crank chamber pressure Pc and suction pressure Ps When the differential pressure Δp exceeds a predetermined value (for example, 0.5 atm), the stroke of the piston 0 is reduced, the tilt angle of the swinging inclined plate 17 is reduced, and the operation is shifted to a small capacity operation.

On the other hand, during full capacity operation, if the engine etc. is rapidly accelerated and the rotational speed of the drive shaft 8 suddenly increases, the suction pressure Ps decreases, but the opening degree of the second M closing valve 39 increases. Therefore, the crank chamber pressure Pc is quickly reduced, and therefore the fluctuation in the differential pressure Δp is reduced, and the capacity reduction is reduced.

Also, during full capacity operation when the opening degree of the valve body 38 of the second on-off valve 39 is increased, for example, if the engine brake is applied and the suction pressure Ps suddenly becomes higher than the crank chamber pressure Pc, the suction Since gas quickly flows from the chamber 4 to the crank chamber 7, fluctuations in the differential pressure Δp are reduced,
Therefore, the reduction in compression capacity is also reduced. Then, when the compressor is returned to steady operation and the suction pressure Ps becomes low, the gas is quickly returned from the crank chamber 7 to the suction chamber 4, and the differential pressure Δp is returned to the predetermined value, and the Capacity operation will be promptly restored.

Further, in this embodiment, when the first on-off valve 34 is closed and the pressure in the compression chamber becomes high due to an excessive cooling load, and the amount of gas probed from the compression chamber to the crank chamber increases, the second on-off valve 34 is closed. The opening degree of the on-off valve 39 increases,
Therefore, it is possible to prevent the crank chamber pressure Pc from increasing and maintain the crank chamber pressure almost constant.

Note that the present invention can also be embodied as follows.

As shown in FIG. 5, the crank chamber 7 and the pressure-sensitive chamber 28 are communicated with each other by a pressure guide path 29 having a large passage cross-sectional area.
and the valve chamber 37 are communicated with each other by a passage 41 having a large passage cross-sectional area, and in this other example, the pressure guiding passage 29, the pressure sensitive chamber 28, and the passage 41 also serve as a part of the bleed passage 40. different from.

Effects of the Invention As detailed above, this invention can be used during steady driving, for example, when engine braking is activated, when a special sudden deceleration is performed when entering a parking area from a highway, or when the speed is reduced to a constant speed after sudden acceleration is completed. Even when returning to normal operation, the pressure in the crank chamber can be accurately maintained at the set pressure, and unnecessary fluctuations in capacity can be minimized. This has the effect of quickly performing control and improving capacity control characteristics.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a compressor showing an embodiment of the present invention;
FIG. 2 is an enlarged sectional view of the control device, FIGS. 3 and 4 are enlarged sectional views for explaining the operation, and FIG. 5 is an enlarged sectional view showing another example of the control device. 4... Suction chamber, 5... Discharge chamber, 6... Crank chamber, 17... Rocking inclined plate, 20... Control valve, 21-2
3... First to third cases, 24... Bellows, 25
... Operating rod, 26.33... Spring, 27... Atmospheric chamber, 28... Pressure sensitive chamber, 29-... Pressure guiding path, 30...
Valve control mechanism, 31.37... Valve chamber, 32.38...
Valve body, 34... first on-off valve, 35... air supply passage, 3
9... Second on-off valve, 40... Bleed passage, 41...
Passage, Ps...Suction pressure, Pc...Crank chamber pressure, Pd...Discharge pressure.

Claims (2)

[Claims] 1. It is equipped with a suction chamber, a discharge chamber, and a crank chamber, and the piston stroke is changed according to the differential pressure between the crank chamber pressure and the suction pressure, and the inclination angle of the oscillating inclined plate is changed to control the compression capacity. In a variable displacement compressor of a variable angle swinging inclined plate type, an air supply passage communicating with a discharge chamber and a crank chamber, and an air bleed passage communicating with the crank chamber and a suction chamber are provided, and the air supply passage includes A first on-off valve is provided in the bleed passage, and a second on-off valve is provided in the bleed passage.
A valve control mechanism that operates in response to changes in crank chamber pressure opens the first opening/closing valve, reduces the opening degree of the second opening/closing valve, and vice versa when the crank chamber pressure falls below the set pressure. A variable capacity compressor that can be controlled to close the first on-off valve and increase the opening degree of the second on-off valve when the pressure in the crank chamber exceeds a set pressure. 2. The valve control mechanism (30) includes a bellows (24) housed inside the first case (21), and a bellows (24) housed inside the first case (21).
) and the bellows (24).
) is housed in an atmospheric chamber (27) within the operating rod (25).
The first on-off valve (34) is opened, and the second on-off valve (39) is opened.
); a spring (26) that biases the opening degree of the
It is composed of a pressure sensitive chamber (28) provided on the outside of the bellows (24) and a pressure guide path (29) that guides refrigerant gas from the crank chamber to the pressure sensitive chamber (28). (25) is constructed separately from the valve body (32) of the first on-off valve (34), and the valve body (38) of the second on-off valve (39) is attached to the operating rod (25). A variable displacement compressor according to claim 1.