JP2002285973A - Compression capacity control device for refrigeration cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compression capacity control device for refrigeration cycle which does not require a clutch for making a compressor not to operate and capable of greatly reducing device cost. SOLUTION: In a compressor capacity control device for refrigeration cycle, including a variable displacement compressor 10 compressing coolant sucked from a suction chamber 3 connected to a suction pipe 1 discharging the same to a discharge chamber 4 connected to a discharge pipe 2 and varying the discharging quantity of coolant according to pressure variation of a pressure regulating chamber 12, in which the pressure is controlled by a solenoid control valve 20, the discharge quantity of the variable displacement compressor 10 is set to minimum with for the variable range, when the solenoid control valve 20 is not energized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression capacity control device for a refrigeration cycle used in an air conditioner for an automobile or the like.

[0002]

2. Description of the Related Art A compressor used in a refrigeration cycle of an air conditioner for a vehicle cannot directly control the number of revolutions because it is directly connected to an engine by a belt. Therefore, in order to obtain an appropriate cooling capacity without being restricted by the engine speed, a variable displacement compressor capable of changing a compression capacity (discharge amount) is used.

[0003] Such a variable displacement compressor generally compresses refrigerant sucked from a suction chamber leading to a suction pipe, discharges it to a discharge chamber leading to a discharge pipe, and is pressure-controlled by an electromagnetic control valve or the like. The discharge amount of the refrigerant is changed by changing the pressure of the chamber.

[0004]

In a conventional apparatus, a pulley portion receiving rotation of a belt directly connected to an engine in order to prevent the compressor from being driven in an operation state in which it is not necessary to compress the refrigerant. Is provided with an electromagnetic clutch or the like, and the cost of the apparatus is increased in order to prevent the operation of the compressor.

Accordingly, an object of the present invention is to provide a compression capacity control device for a refrigeration cycle which does not require a clutch for preventing the operation of the compressor and can greatly reduce the cost of the device.

[0006]

In order to achieve the above object, a compression capacity control apparatus for a refrigeration cycle according to the present invention compresses refrigerant sucked from a suction chamber leading to a suction pipe and discharges the refrigerant to a discharge pipe. In a compression capacity control device of a refrigeration cycle having a variable capacity compressor that discharges refrigerant into a chamber and changes a discharge amount of refrigerant by a pressure change of a pressure regulation chamber pressure-controlled by an electromagnetic control valve, the electromagnetic control valve When there is no power supply, the variable displacement compressor is in a state of a minimum discharge amount in a variable range.

The electromagnetic control valve is configured to maintain the pressure difference between at least one of the pressure in the pressure control chamber and the pressure in the suction chamber and the pressure in the discharge chamber at a predetermined pressure difference. By communicating and closing the chamber, the differential pressure changes by changing the electromagnetic force of the electromagnetic control valve, thereby changing the pressure in the pressure regulating chamber and controlling the refrigerant discharge amount. You may.

Further, there is provided an urging means for maintaining the electromagnetic control valve in the open state when the electromagnetic control valve is not energized, and the variable displacement compressor is provided by maintaining the electromagnetic control valve in the open state. The discharge amount of the minimum range of the variable range may be set.

[0009] A suction path opening / closing valve may be provided to close the suction pipe and the suction chamber when the pressure difference between the discharge chamber and the suction chamber falls below a predetermined value.

[0010]

Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 10 denotes a swash plate type variable capacity compressor, which is used in a refrigeration cycle for air conditioning of an automobile. As the refrigerant, R134A or the like is used, but the present invention may be applied to a refrigeration cycle using carbon dioxide as the refrigerant.

Reference numeral 11 denotes an airtight crankcase 12.
(A pressure adjusting chamber), which is connected to an axial position of a pulley 13 which is rotationally driven by a drive belt (not shown) directly connected to the engine, and
With the rotation of, the swing plate 14 disposed in the crank chamber 12 at an angle to the rotation shaft 11 swings.

A piston 17 is reciprocally movable in a cylinder 15 arranged at a peripheral portion in the crank chamber 12, and the piston 17 and the swing plate 1 are moved by a rod 18.
4 are connected.

As a result, when the swinging plate 14 swings, the piston 17 reciprocates in the cylinder 15 and a low-pressure (suction pressure Ps) refrigerant is sucked into the cylinder 15 from the suction chamber 3, and the refrigerant is The refrigerant that has been compressed in the cylinder 15 and has become high pressure (discharge pressure Pd) is discharged to the discharge chamber 4.

Refrigerant is fed into the suction chamber 3 from the evaporator (not shown) on the upstream side via the suction pipe 1.
The high-pressure refrigerant is discharged from the discharge chamber 4 to the condenser (not shown) on the downstream side via the discharge pipe 2.

The inclination angle of the oscillating plate 14 changes depending on the pressure in the crank chamber 12 (crank chamber pressure Pc), and the amount of refrigerant discharged from the cylinder 15 (ie, the compression capacity) depends on the inclination angle of the oscillating plate 14. Change.

The discharge amount is large when the rocking plate 14 is inclined as shown by the solid line, and is small when the rocking plate 14 is not inclined as shown by the two-dot chain line. When the swing plate 14 is perpendicular to the rotation axis 11, the discharge amount becomes zero.

However, as the oscillating plate 14 gradually shifts to a state without inclination (a state approaching the two-dot chain line),
The minimum securing spring 19 mounted around the rotating shaft 11 is gradually compressed by the swing plate 14.

As a result, the reaction force from the minimum securing spring 19 to the oscillating plate 14 gradually increases, and the oscillating plate 14 does not reach the direction perpendicular to the rotating shaft 11 and the discharge amount is the maximum. The amount is, for example, not less than about 3 to 5%.

Such an operation state in which the discharge amount is minimum is called minimum operation. Note that such a minimum securing spring 19 is known, and has a configuration in which, for example, a wave spring and a coil spring are combined.

Reference numeral 20 denotes a capacity control solenoid valve (electromagnetic control valve) for electromagnetic solenoid control for performing compression capacity control by automatically controlling the crank chamber pressure (Pc). 21 is an electromagnetic coil, 22 is a fixed iron core.

The movable iron core 23 and the valve body 25 are fixed to the fixed iron core 22.
It is connected by a rod 24 which is arranged so as to pass through the inside and is capable of moving back and forth in the axial direction.

Reference numeral 29 denotes an O-ring for sealing. In addition, the urging force of the two compression coil springs 27, 28 is greater for the valve opening spring 28 than for the valve closing spring 27.
It is set larger.

The valve seat 26 has a crank chamber communication passage 5 communicating with the crank chamber 12 and a discharge chamber communication passage 6 communicating with the discharge chamber 4.
, And the valve body 25 is disposed to face the valve seat 26 from the crank chamber communication passage 5 side. The crank chamber communication passage 5 and the suction pipe line 1 communicate with each other through a thin leak passage 7.

With such a configuration, the differential pressure (Pd) between the discharge pressure (Pd) and the crank chamber pressure (Pc) is applied to the valve body 25.
-Pc) acts in the opening direction, and in the closing direction, the electromagnetic force (compression coil springs 27, 28) of the capacity control solenoid valve 20.
Act).

Therefore, when the value of the current supplied to the electromagnetic coil 21 is constant and the electromagnetic force of the displacement control solenoid valve 20 is constant, the differential pressure (Pd-Pc) between the discharge pressure (Pd) and the crank chamber pressure (Pc) is obtained. The valve body 25 is opened and closed with the fluctuation of the pressure, and the differential pressure (Pd-Pc) is kept constant, whereby the crank chamber pressure (Pc) is controlled to a value corresponding to the discharge pressure (Pd), and the compression capacity is changed. (Discharge amount) is kept constant.

When the value of the current flowing through the electromagnetic coil 21 is changed to change the electromagnetic force of the displacement control solenoid valve 20, the differential pressure (Pd-Pc) kept constant changes accordingly. As a result, the compression capacity (discharge amount) is kept constant at different levels.

That is, when the electromagnetic force of the displacement control solenoid valve 20 is reduced, the differential pressure (Pd-Pc) that is kept constant is reduced, so that the crank chamber pressure (Pc) becomes equal to the discharge pressure (Pc).
The temperature rises in the direction approaching d), and the swing plate 14 approaches the direction perpendicular to the rotating shaft 11, so that the refrigerant discharge amount decreases.

Conversely, when the electromagnetic force of the displacement control solenoid valve 20 is increased, the differential pressure (Pd-Pc) that is kept constant increases, so that the crank chamber pressure (Pc) increases with the discharge pressure (Pc).
d), the inclination angle of the swing plate 14 with respect to the rotating shaft 11 increases, and the refrigerant discharge amount increases.

The value of the current supplied to the electromagnetic coil 21 is controlled by detecting signals from the engine, temperatures inside and outside the vehicle, evaporator sensors, and other sensors for detecting various conditions.
The control signal is input to the control unit 40 having a built-in PU or the like, and a control signal based on the calculation result is sent from the control unit 40 to the electromagnetic coil 21 to be performed. The drive circuit of the electromagnetic coil 21 is not shown.

When the power supply to the electromagnetic coil 21 is stopped, the valve body 25 is moved due to the difference between the urging forces of the two compression coil springs 27 and 28 for urging the valve body 25 of the displacement control electromagnetic valve 20. The valve is in an open state away from the valve seat 26.

Then, the pressure difference between the discharge pressure (Pd) and the crank chamber pressure (Pc) disappears (that is, Pd-Pc ≒).
0) The swinging plate 14 is about to be oriented perpendicular to the rotating shaft 11, but before that, the inclined state of the swinging plate 14 balances the reaction force from the minimum securing spring 19, and the compressor 1
0 indicates a state in which the minimum operation is maintained.

As described above, when the power supply to the electromagnetic coil 21 of the displacement control electromagnetic valve 20 is stopped, the compressor 10 enters the minimum operation state. Therefore, even when the compressor 10 does not need to be operated, the rotary shaft 11 is driven to rotate. You can leave it in the state.

FIG. 2 shows a displacement control solenoid valve 20 according to a second embodiment of the present invention. The compressor 10 is the same as that of the first embodiment and is not shown. In addition, the leak path is appropriately arranged.

In this embodiment, a piston rod 25p having the same pressure receiving area as the valve seat 26 is provided integrally on the back side of the valve body 25, and the suction chamber communication passage 8 is provided in a space facing the back surface of the piston rod 25p. The crank chamber communication passage 5 is connected to a space facing the side surface of the piston rod 25p, and the discharge chamber communication passage 6 is connected to a space behind the valve seat 26 when viewed from the valve body 25 side.

As a result, the piston rod 25p and the valve body 2
5 is canceled, and the differential pressure (P) between the discharge pressure (Pd) and the suction pressure (Ps) is canceled.
d-Ps) causes the valve body 25 to open and close, whereby the space between the crank chamber 12 and the discharge chamber 4 is opened and closed to control the compression capacity.

When the power supply to the electromagnetic coil 21 is stopped, the valve body 25 is opened away from the valve seat 26 by the difference between the urging forces of the two compression coil springs 27 and 28, and the minimum operation is maintained. State.

As described above, according to the present invention, the pressure difference between at least one of the pressure (Pc) in the crank chamber 12 and the pressure (Ps) in the suction pipe line 1 and the pressure (Pd) in the discharge chamber 4 is set to a predetermined pressure difference. The pressure difference between the crank chamber 12 and the discharge chamber 4 is changed by changing the electromagnetic force of the displacement control solenoid valve 20 to change the pressure (Pc) of the crank chamber 12. Can be applied to a device in which the discharge amount changes by the change of the discharge amount, and can also be applied to a device controlled by another method.

FIG. 3 shows a third embodiment of the present invention. In the apparatus having the same structure as that of the first embodiment, the pressure difference between the discharge chamber 4 and the suction chamber 3 is equal to or less than a predetermined value. Then, a suction passage opening / closing valve 30 for closing the space between the suction pipe line 1 and the suction chamber 3 is provided.

In this embodiment, a valve body 32 arranged between the suction pipe 1 and the suction chamber 3 so as to face the valve seat 31 from the suction pipe 1 side in the valve closing direction. It is arranged by being urged by a compression coil spring 33. Reference numeral 34 denotes a spring receiver in which a large notch is formed so as not to hinder the passage of the refrigerant.

The pressure receiving piston 3 receives the pressure (Pd) of the discharge chamber 4 and the pressure (Ps) of the suction chamber 3 from both sides.
5 is connected to the valve body 32, and the pressure (P
d) and the pressure difference (Pd−Ps) between the suction chamber 3 and the pressure (Ps).
Is greater than a certain value, the valve element 32 is separated from the valve seat 31 and the suction passage opening / closing valve 30 is open. When the valve enters the minimum operation state and the differential pressure (Pd−Ps) becomes smaller than a predetermined value, the valve element 32 The suction passage opening / closing valve 30 is closed by being pressed against the seat 31.

In this way, the low-pressure refrigerant in the suction line 1 is not sucked into the compressor 10 during the minimum operation.
The fins of the evaporator can be prevented from freezing during the minimum operation when the load is small as in winter.

[0042]

According to the present invention, the variable displacement compressor maintains the minimum discharge amount in the variable range when the electromagnetic control valve is not energized, so that the compressor is not operated. This eliminates the need for a clutch, and can significantly reduce the cost of the apparatus.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an overall configuration of a compression capacity control device for a refrigeration cycle according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a displacement control solenoid valve according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing an entire configuration of a compression capacity control device for a refrigeration cycle according to a third embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 suction pipe 2 discharge pipe 3 suction chamber 4 discharge chamber 10 compressor (variable capacity compressor) 12 crank chamber (pressure regulating chamber) 14 rocking plate 19 minimum securing spring 20 capacity control solenoid valve (electromagnetic control valve) 27 , 28 Compression coil spring 30 Suction path opening / closing valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H045 AA04 AA10 AA12 AA27 BA12 CA01 EA13 EA33 3H076 AA06 BB33 BB41 CC12 CC16 CC20

Claims (4)

[Claims] 1. A refrigerant sucked from a suction chamber connected to a suction pipe is compressed and discharged to a discharge chamber connected to a discharge pipe, and the refrigerant is discharged by a pressure change in a pressure control chamber pressure-controlled by an electromagnetic control valve. In the compression capacity control device for a refrigeration cycle having a variable capacity compressor having a variable capacity, the state in which the variable capacity compressor has a variable range minimum discharge amount in a state where the electromagnetic control valve is not energized. A compression capacity control device for a refrigeration cycle, characterized in that: 2. The pressure regulating chamber, wherein the electromagnetic control valve maintains a differential pressure between at least one of the pressure in the pressure regulating chamber, the pressure in the suction chamber, and the pressure in the discharge chamber at a predetermined differential pressure. And the discharge chamber or the suction chamber is communicated and closed, and by changing the electromagnetic force of the electromagnetic control valve, the differential pressure changes to change the pressure of the pressure regulating chamber, thereby changing the discharge amount of the refrigerant. The compression capacity control device for a refrigeration cycle according to claim 1, wherein the pressure is controlled. 3. An urging means is provided for maintaining the electromagnetic control valve in an open state when the electromagnetic control valve is not energized, and the capacity is maintained by maintaining the electromagnetic control valve in an open state. The compression capacity control device for a refrigeration cycle according to claim 1 or 2, wherein the variable compressor has a minimum discharge amount in a variable range. 4. A suction path opening / closing valve which closes between the suction pipe and the suction chamber when a pressure difference between the discharge chamber and the suction chamber becomes equal to or lower than a predetermined value. Or a compression capacity control device for a refrigeration cycle according to 3.