JPH06341378A - Capacity control device of variable capacity compressor - Google Patents

Abstract

PURPOSE:To provide a capacity control device for variable capacity compressor which can simply obtain a capacity change according to necessity by the use of a constant differential pressure valve and can nevertheless acquire a high compressing efficiency. CONSTITUTION:A capacity control device for a variable capacity compressor is equipped with a low pressure communication path 25 which is to put a crank chamber 12 in communication with a suction chamber 20 so that a refrigerant is leaked from inside of the crank chamber 12 into the suction chamber 20, a high pressure communication path 27 which puts a discharge chamber 21 in communication with the crank chamber 12 so that the refrigerant is leaked from inside of the discharge chamber 21 into the crank chamber 12, and a solenoid-operated constant differential pressure valve 30 which opens and closes the high pressure communication path 27 so that the differential pressure Pc-Ps between the pressure Pc in the crank chamber 12 and the pressure Ps in the suction chamber 20 is adjusted to any pressure constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity control device for a capacity variable compressor used for compressing a refrigerant in a refrigeration cycle of an automobile air conditioner (hereinafter referred to as "car air conditioner").

Since the compressor of a car air conditioner is directly connected to the engine by a belt, the rotation speed cannot be controlled. Therefore, a variable capacity compressor capable of changing the capacity (discharge amount) of the refrigerant is used in order to obtain an appropriate cooling capacity without being restricted by the engine speed.

In such a variable displacement compressor, a compression piston is connected to an oscillating body mounted on a shaft which is rotationally driven by an engine, and the stroke of the piston is changed by changing the angle of the oscillating body. The capacity of the refrigerant is changed.

[0004]

2. Description of the Related Art In such a variable capacity compressor, in order to change the angle of an oscillating body as required, conventionally, an electromagnetic force is used to control the pressure of the refrigerant sucked into the compressor to a predetermined pressure. A driven electromagnetic constant pressure valve is provided, and the pressure of the refrigerant sucked into the compressor is changed to change the angle of the oscillator to control the capacity of the refrigerant.

However, such an electromagnetically driven constant pressure valve is
Since it is necessary to compare it with the atmospheric pressure, which is an almost invariable physical quantity, as a reference, it is necessary to use a bellows, a diaphragm, etc. to make an airtight and smooth structure, and also a very powerful electromagnetic device. Therefore, there is a drawback that the device is large and the cost is high.

Therefore, an electromagnetically driven constant differential pressure valve for maintaining a differential pressure between the pressure in the crank chamber in which the oscillating body is arranged and the pressure of the refrigerant sucked into the cylinder for compressing the refrigerant at an arbitrary constant differential pressure is provided. There is one in which the capacity of the compressor is changed by changing the electromagnetic force of the differential pressure valve.

Here, the discharge chamber for discharging the high-pressure refrigerant compressed in the cylinder and the crank chamber are communicated with each other through a fixed orifice, and the pressure in the crank chamber is compensated by the pressure in the discharge chamber, and the suction chamber is compensated. When the pressure decreases, the constant differential pressure valve is opened so that the refrigerant in the crank chamber is leaked to the suction chamber side so that the differential pressure becomes constant.

As described above, if the differential pressure between the pressure in the crank chamber and the pressure in the suction chamber is controlled by the electromagnetically driven constant differential pressure valve, the capacity can be easily changed with a small device.

[0009]

However, in the configuration in which the crank chamber and the discharge chamber are communicated with each other by the fixed orifice, the high-pressure refrigerant in the discharge chamber constantly leaks to the crank chamber to lower the pressure in the discharge chamber. Become.

For this reason, conventionally, there has been a problem that even in the case of a high load, for example, where the compression capacity is 100%, the pressure in the discharge chamber is reduced by the leak to the crank chamber, and high compression efficiency cannot be obtained.

Therefore, the present invention is to provide a capacity control device for a capacity variable compressor which can easily change the capacity as required by using a constant differential pressure valve and can obtain high compression efficiency. To aim.

[0012]

In order to achieve the above object, a displacement control device for a variable displacement compressor according to the present invention has a variable inclination angle with respect to a rotary shaft 11 in an airtightly formed crank chamber 12. An oscillating body 14 which is provided and is oscillated by the rotational movement of the rotating shaft 11, and the oscillating body 1
4, the refrigerant from the suction chamber 20 is sucked into the cylinder 15 by being reciprocated and compressed, and then discharged into the discharge chamber 2.
And a piston 17 for discharging to the crank chamber 1
In the variable displacement compressor 1 in which the inclination angle of the oscillating body 14 is changed according to the difference between the pressure inside the suction chamber 20 and the pressure inside the suction chamber 20, the discharge amount of the refrigerant is changed. The low pressure communication passage 25 for communicating with the suction chamber 20 to leak the refrigerant from the crank chamber 12 into the suction chamber 20, and the discharge chamber 21 and the crank chamber 12 are communicated with each other. High pressure communication passage 2 for leaking the refrigerant from the inside into the crank chamber 12
7, the pressure Pc in the crank chamber 12 and the suction chamber 2
An electromagnetically driven constant differential pressure valve 30 for opening and closing the high pressure communication passage 27 is provided so as to adjust the differential pressure Pc-Ps with respect to the pressure Ps within 0 to an arbitrary constant pressure.

[0013]

When the pressure Ps in the suction chamber 20 decreases,
The pressure Pc in the crank chamber 12 is a differential pressure Pc-P due to the leakage of the refrigerant into the suction chamber 20 through the low pressure communication passage 25.
It decreases until s becomes constant. At this time, the constant differential pressure valve 3
0 is closed, and there is no communication between the discharge chamber 21 and the crank chamber 12.

When the pressure Pc in the crank chamber 12 further decreases or the pressure Ps in the suction chamber 20 rises, the constant differential pressure valve 30 operates to open the high pressure communication passage 27, and the discharge chamber. By sending the refrigerant in 21 into the crank chamber 12, the pressure Pc in the crank chamber 12 rises,
Pressure Pc in the crank chamber 12 and pressure Ps in the suction chamber 20
The pressure difference between and is kept constant.

When the driving electromagnetic force of the constant differential pressure valve 30 is changed, the differential pressure that is maintained constant changes, so that the tilt angle of the oscillating body 14 changes and the compression capacity changes.

[0016]

Embodiments will be described with reference to the drawings. Figure 1
It shows the refrigeration cycle used for car air conditioners,
2 is a condenser, 3 is an expansion valve, and 4 is an evaporator. The liquid receiver is not shown.

A low-pressure refrigerant is sent from the evaporator 4 to the compressor 1, and the high-pressure refrigerant compressed by the compressor 1 is sent to the condenser 2. The compressor 1 will be described below.

Reference numeral 11 denotes a crank chamber 12 which is airtightly constructed.
An oscillating body 14 that is disposed inside and is rotatably driven by a drive pulley 13 and that is inclined with respect to the rotating shaft 11 is oscillated by the rotation of the rotating shaft 11.

In a plurality of cylinders 15 arranged in the peripheral portion of the crank chamber 12, a piston 17 is reciprocally arranged, and a rod 18 connects the piston 17 and the oscillating body 14.

Therefore, when the oscillating body 14 oscillates, the piston 17 reciprocates in the cylinder 15 and the cylinder 1
The refrigerant is drawn from the suction chamber 20 formed in the back of the cylinder 5 into the cylinder 15
The refrigerant is sucked in, the refrigerant is compressed, and then discharged into the discharge chamber 21.

The suction chambers 20 and the discharge chambers 2 are connected to each other.
One of them communicates with each other through communication passages 23 and 24, and the suction chamber 20 and the crank chamber 12 communicate with each other through a thin fixed orifice 25 (low pressure communication passage) serving as a leak passage.

The tilt angle of the oscillating body 14 is determined by the pressure difference "Pc-" between the pressure Pc in the crank chamber 12 and the pressure Ps in the suction chamber 20.
Ps ”, the stroke of the piston 17 changes when the tilt angle of the oscillating body 14 changes, so the discharge amount (capacity) of the compressor 1 changes.

Reference numeral 30 denotes an electromagnetically driven constant differential pressure valve, which changes the current value passed through the electromagnetic solenoid 31 to change the differential pressure "Pc-Ps" between the pressure Pc in the crank chamber 12 and the pressure Ps in the suction chamber 20. It is for adjusting to an arbitrary constant pressure. FIG. 2 shows the part in an enlarged manner.

The discharge chamber 21 and the crank chamber 12 can communicate with each other through a high pressure communication passage 27, and a ball valve 32 of a constant differential pressure valve 30 opens and closes the high pressure communication passage 27 from the discharge chamber 21 side. It is arranged so as to face the valve seat 33 and be biased by a coil spring 34. A passage for communicating the discharge chamber 21 and the crank chamber 12 is not formed except the high pressure communication passage 27.

The pressure receiving member 35 of the constant differential pressure valve 30 is connected to the movable iron core 31b driven by the electromagnetic coil 31a of the electromagnetic solenoid 31 via the rod 31c, and the value of the current supplied to the electromagnetic coil 31a should be considered. By
The urging force of the electromagnetic force applied to the pressure receiving member 35 changes.

The pressure receiving member 35 and the ball valve 32 are in constant communication with the inside of the crank chamber 12 through a half portion of the high pressure communication passage 27, and the other surface side of the pressure receiving member 35 is connected to the passage 2
8 communicates with the suction chamber 20.

Therefore, the constant differential pressure valve 30 operates so that the electromagnetic force and the coil spring 34 are balanced and the pressure Pc in the crank chamber 12 and the pressure Ps in the suction chamber 20 are balanced, and Pc-Ps is When it becomes smaller than a certain value, the ball valve 32 separates from the valve seat 33, the high pressure communication passage 27 opens, and the discharge chamber 21 and the crank chamber 12 communicate with each other.

The constant differential pressure valve 30 is formed in a unit as a whole and is attached to the compressor 1, and an O-ring 39 for sealing is attached to a portion where leakage must be prevented. 40 is a filter.

Reference numeral 50 shown in FIG. 1 is a control unit for controlling the current value and the like applied to the electromagnetic coil 31a of the constant differential pressure valve 30, and the two thermistors 6 attached to the pipes before and after the expansion valve 3. The detection signal (that is, the refrigerant temperature information) from 7 is input, and the current value flowing through the electromagnetic coil 31a is controlled accordingly, and the level of the value can be freely adjusted by the input from the setting unit 51. .

According to the embodiment apparatus constructed as described above, when the pressure Ps in the suction chamber 20 is lowered, the refrigerant leaks into the suction chamber 20 through the fixed orifice 25, and thus the inside of the crank chamber 12 is closed. Pressure Pc is differential pressure Pc-P
It decreases until s becomes constant.

As described above, when the pressure in the suction chamber 20 is low and the compressor 1 needs to be operated under high load,
The constant differential pressure valve 30 does not open, and the high pressure communication passage 27 does not have the ball valve 32.
The refrigerant in the discharge chamber 21 does not leak into the crank chamber 12 or the like because it is blocked by. Therefore, the discharge chamber 2
The pressure Pd in 1 is maintained at a high pressure.

When the pressure Pc in the crank chamber 12 further drops below that or the pressure Ps in the suction chamber 20 rises, the ball valve 3 is balanced by the force balance of the constant differential pressure valve 30.
2 is separated from the valve seat 33, the high pressure communication passage 27 is opened, and the refrigerant of high pressure Pd in the discharge chamber 21 is sent into the crank chamber 12, whereby the pressure Pc in the crank chamber 12 rises,
Pressure Pc in the crank chamber 12 and pressure Ps in the suction chamber 20
The differential pressure Pc-Ps between and is maintained constant.

If the value of the current passed through the electromagnetic coil 31 of the constant differential pressure valve 30 changes under the control of the control unit 50, the differential pressure Pc- between the pressure Pc in the crank chamber 12 and the pressure Ps in the suction chamber 20. Ps changes, whereby the tilt angle of the oscillating body 14 changes, the stroke of the piston 17 changes, and the capacity changes.

[0034]

According to the capacity control device for a variable capacity compressor of the present invention, the capacity of the compressor can be easily controlled by a constant differential pressure valve driven by current, and moreover, when the load is high, the capacity of the discharge chamber to the crank chamber is reduced. Since there is no leakage of the refrigerant such as, the compression operation can be performed with high compression efficiency.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a variable capacity compressor according to an embodiment.

FIG. 2 is an enlarged cross-sectional view of a constant pressure differential valve of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacity variable compressor 11 Rotating shaft 12 Crank chamber 14 Oscillator 15 Cylinder 17 Piston 20 Suction chamber 21 Discharge chamber 25 Fixed orifice (low pressure communication passage) 27 High pressure communication passage 30 Constant differential pressure valve 31 Electromagnetic solenoid 32 Ball valve

Claims (1)

[Claims] 1. A crank chamber (12) formed in an airtight manner is provided with a variable inclination angle with respect to a rotary shaft (11) and is driven by the rotary motion of the rotary shaft (11) to perform a swing motion. The oscillating body (14) is connected to the oscillating body (14) and reciprocates so that the refrigerant from the suction chamber (20) is sucked into the cylinder (15) and compressed, and then discharged to the discharge chamber (21). A discharge piston (17), and the pressure in the crank chamber (12) and the suction chamber (20).
In the variable capacity compressor (1) in which the inclination angle of the oscillating body (14) is changed by the difference between the internal pressure and the discharge amount of the refrigerant, the crank chamber (12) and the suction chamber ( 20) to communicate with the suction chamber (2) from the inside of the crank chamber (12).
0) Low pressure communication passage (25) for leaking the refrigerant into
The discharge chamber (21) and the crank chamber (12) are communicated with each other so that the crank chamber (1
2) High pressure communication passage (27) for leaking refrigerant into the inside
And the high pressure communication passage for adjusting the pressure difference (Pc-Ps) between the pressure (Pc) in the crank chamber (12) and the pressure (Ps) in the suction chamber (20) to an arbitrary constant pressure. An electromagnetically driven constant differential pressure valve (30) for opening and closing (27) is provided.