JP4070425B2 - Compression capacity controller for refrigeration cycle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compression capacity control device for a refrigeration cycle used in an automotive air conditioner or the like.
[0002]
[Prior art]
Since the compressor used in the refrigeration cycle of the air conditioner for automobiles is directly connected to the engine with a belt, the rotational speed cannot be controlled. Therefore, a variable capacity compressor capable of changing the compression capacity (discharge amount) is used in order to obtain an appropriate cooling capacity without being restricted by the rotational speed of the engine.
[0003]
Such a variable capacity compressor generally compresses the refrigerant sucked from the suction chamber leading to the suction pipe and discharges it to the discharge chamber leading to the discharge pipe, and the pressure of the pressure regulating chamber controlled by an electromagnetic control valve or the like. The refrigerant discharge amount is changed by the change.
[0004]
[Problems to be solved by the invention]
In the conventional apparatus, an electromagnetic clutch or the like is provided in a pulley portion that receives rotation of a belt directly connected to the engine so as not to drive the compressor in an operation state in which it is not necessary to compress the refrigerant. In order to prevent the compressor from being operated, the cost of the apparatus has been bothered.
[0005]
Accordingly, an object of the present invention is to provide a compression capacity control device for a refrigeration cycle that does not require a clutch for preventing operation of the compressor and can significantly reduce the device cost.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a compression capacity control device for a refrigeration cycle according to the present invention compresses a refrigerant sucked from a suction chamber that leads to a suction pipe and discharges it to a discharge chamber that leads to a discharge pipe. in the compression capacity control apparatus for a refrigeration cycle having a variable displacement compressor so as to vary the discharge amount of the refrigerant by the pressure change in the pressure regulating chamber to be pressure controlled, solenoid control valves, pressure regulating chamber pressure and the discharge chamber of the The pressure in the pressure regulating chamber is changed by communicating and closing between the pressure regulating chamber and the discharge chamber, and the electromagnetic force is changed so as to keep the pressure difference from the pressure at a predetermined pressure. The first spring for urging the valve body that communicates and closes the pressure regulating chamber and the discharge chamber in the valve closing direction, and the valve body in the valve opening direction. Larger than the first spring And a second spring having a biasing force, is obtained as a variable capacity compressor is in a state of minimum discharge amount of the variable range by maintaining the valve body in the open state when the state without energization .
[0009]
In addition, a suction path opening / closing valve that closes between the suction pipe and the suction chamber may be provided when the differential pressure between the discharge chamber and the suction chamber becomes a predetermined pressure or less.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
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 an air conditioning refrigeration cycle of an automobile. R134A or the like is used as the refrigerant, but the present invention may be applied to a refrigeration cycle using carbon dioxide as the refrigerant.
[0011]
Reference numeral 11 denotes a rotating shaft disposed in an airtight crank chamber 12 (pressure regulating chamber), which is connected to the shaft position of a pulley 13 that is rotationally driven by a driving belt (not shown) directly connected to the engine. As the rotary shaft 11 rotates, the swing plate 14 disposed in the crank chamber 12 is tilted with respect to the rotary shaft 11 and swings.
[0012]
A piston 17 is disposed in a reciprocating manner in a cylinder 15 disposed in the periphery of the crank chamber 12, and the piston 17 and the swing plate 14 are connected by a rod 18.
[0013]
As a result, when the swing 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. Then, the refrigerant that has been compressed at the high pressure (discharge pressure Pd) is discharged into the discharge chamber 4.
[0014]
Refrigerant is fed into the suction chamber 3 from the upstream evaporator (not shown) side via the suction pipe 1, and from the discharge chamber 4 to the downstream condenser (not shown) side. High-pressure refrigerant is sent out via the discharge pipe 2.
[0015]
The inclination angle of the swing plate 14 changes depending on the pressure of the crank chamber 12 (crank chamber pressure Pc), and the refrigerant discharge amount (that is, the compression capacity) from the cylinder 15 changes depending on the inclination angle of the swing plate 14.
[0016]
The discharge amount is often when the oscillating plate 14 is inclined as indicated by the solid line, and is decreased when it is not inclined as indicated by the two-dot chain line. When the swing plate 14 is perpendicular to the rotating shaft 11, the discharge amount becomes zero.
[0017]
However, as the swing plate 14 gradually shifts to a state without inclination (a state approaching the two-dot chain line), the minimum securing spring 19 that is mounted around the rotating shaft 11 is gradually compressed by the swing plate 14.
[0018]
As a result, the reaction force from the minimum securing spring 19 to the swinging plate 14 gradually increases, and the swinging plate 14 does not reach the direction perpendicular to the rotation shaft 11, and the discharge amount is, for example, the maximum discharge amount. It does not become less than about 3-5%.
[0019]
Such an operation state in which the discharge amount is minimum is called minimum operation. Such a minimum securing spring 19 is publicly known, and has a configuration in which, for example, a wave spring and a coil spring are combined.
[0020]
Reference numeral 20 denotes an electromagnetic solenoid control capacity control solenoid valve (electromagnetic control valve) for automatically controlling the crank chamber pressure (Pc) to perform compression capacity control. 21 is an electromagnetic coil, and 22 is a fixed iron core.
[0021]
The movable iron core 23 and the valve body 25 are arranged in a state of passing through the fixed iron core 22 and are connected by a rod 24 that can advance and retreat in the axial direction, and are biased by compression coil springs 27 and 28 from both ends. .
[0022]
Reference numeral 29 denotes an O-ring for sealing. The urging force of the two compression coil springs 27 and 28 is set to be larger in the valve opening spring 28 than in the valve closing spring 27.
[0023]
The valve seat 26 is formed between the crank chamber communication passage 5 communicating with the crank chamber 12 and the discharge chamber communication passage 6 communicating with the discharge chamber 4, and the valve body 25 is connected to the valve seat from the crank chamber communication passage 5 side. 26 is arranged to face 26. The crank chamber communication path 5 and the suction pipe line 1 communicate with each other through a narrow leak path 7.
[0024]
With such a configuration, the differential pressure (Pd−Pc) between the discharge pressure (Pd) and the crank chamber pressure (Pc) acts on the valve body 25 in the opening direction, and in the closing direction, the displacement control solenoid valve 20 Electromagnetic force (including the urging force of the compression coil springs 27 and 28) acts.
[0025]
Therefore, in a state where the current value supplied to the electromagnetic coil 21 is constant and the electromagnetic force of the capacity control solenoid valve 20 is constant, the pressure difference (Pd−Pc) varies between the discharge pressure (Pd) and the crank chamber pressure (Pc). Accordingly, the valve body 25 is opened and closed, 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 (discharge amount) ) Is kept constant.
[0026]
When the electromagnetic current of the capacity control solenoid valve 20 is changed by changing the value of the energization current to the electromagnetic coil 21, the differential pressure (Pd-Pc) kept constant correspondingly changes, thereby compressing. The capacity (discharge amount) is kept constant at different levels.
[0027]
That is, when the electromagnetic force of the capacity control solenoid valve 20 is reduced, the differential pressure (Pd−Pc) that is kept constant decreases, so that the crank chamber pressure (Pc) increases in a direction approaching the discharge pressure (Pd). Then, the swinging plate 14 approaches a direction perpendicular to the rotating shaft 11, and the discharge amount of the refrigerant decreases.
[0028]
Conversely, when the electromagnetic force of the capacity control solenoid valve 20 is increased, the differential pressure (Pd−Pc) that is kept constant increases, so that the crank chamber pressure (Pc) moves away from the discharge pressure (Pd). The angle of inclination of the rocking plate 14 with respect to the rotating shaft 11 increases, and the amount of refrigerant discharged increases.
[0029]
In addition, control of the energization current value to the electromagnetic coil 21 is performed by inputting detection signals from a plurality of sensors for detecting various conditions such as an engine, a temperature inside and outside the vehicle, an evaporator sensor, and the like to a control unit 40 incorporating a CPU and the like. Then, a control signal based on the calculation result is sent from the control unit 40 to the electromagnetic coil 21 and performed. The drive circuit for the electromagnetic coil 21 is not shown.
[0030]
In a state where the energization to the electromagnetic coil 21 is stopped, the valve body 25 is moved to the valve seat 26 due to the difference between the urging forces of the two compression coil springs 27 and 28 that urge the valve body 25 of the capacity control electromagnetic valve 20. Opened away from
[0031]
Then, the pressure difference between the discharge pressure (Pd) and the crank chamber pressure (Pc) disappears (that is, Pd−Pc≈0), and the swing plate 14 tends to be perpendicular to the rotating shaft 11. Before that, the inclined state of the swing plate 14 balances with the reaction force from the minimum securing spring 19, and the compressor 10 is in a state of maintaining the minimum operation.
[0032]
As described above, if the energization of the electromagnetic coil 21 of the capacity control solenoid valve 20 is stopped, the compressor 10 enters the minimum operation state. Therefore, even when the compressor 10 need not be operated, the rotary shaft 11 is driven to rotate. Can be left alone.
[0033]
FIG. 2 shows a capacity control solenoid valve 20 according to the related art of the present invention, and the compressor 10 is omitted because it is the same as that of the first embodiment. Further, the leak path is appropriately arranged.
[0034]
In this embodiment, a piston rod 25p having the same pressure receiving area as the valve seat 26 is integrally provided on the back side of the valve body 25, and the suction chamber communication passage 8 is connected to a space facing the back surface of the piston rod 25p. The crank chamber communication path 5 is connected to the space facing the side surface of the piston rod 25p, and the discharge chamber communication path 6 is connected to the space on the back side of the valve seat 26 when viewed from the valve body 25 side.
[0035]
As a result, the crank chamber pressure (Pc) applied to the piston rod 25p and the valve body 25 is canceled, and the valve body 25 is opened and closed by the differential pressure (Pd−Ps) between the discharge pressure (Pd) and the suction pressure (Ps). By operating, the space between the crank chamber 12 and the discharge chamber 4 is opened and closed, and the compression capacity control is performed.
[0036]
If the energization of the electromagnetic coil 21 is stopped, the valve element 25 is opened away from the valve seat 26 due to the difference in the urging force of the two compression coil springs 27 and 28, and the minimum operation is maintained. Become.
[0037]
As described above, the present invention provides a gap between the crank chamber 12 and the discharge chamber 4 so that the differential pressure between the pressure (Pc ) of the crank chamber 12 and the pressure (Pd ) of the discharge chamber 4 is kept at a predetermined differential pressure. By connecting and closing, and changing the electromagnetic force of the capacity control solenoid valve 20, the above differential pressure changes and the pressure (Pc) of the crank chamber 12 changes, thereby changing the discharge amount. The present invention can be applied to a device controlled by another method.
[0038]
Figure 3 shows a second embodiment of the present invention, the apparatus having the same configuration as that of the first embodiment, further, the suction and the pressure difference between the discharge chamber 4 and the suction chamber 3 becomes less than a predetermined A suction path opening / closing valve 30 for closing the space between the pipe line 1 and the suction chamber 3 is provided.
[0039]
In this embodiment, a valve body 32 disposed in a state of facing the valve seat 31 formed between the suction pipe 1 and the suction chamber 3 from the suction pipe 1 side is a compression coil spring in the valve closing direction. It is urged by 33 and arranged. Reference numeral 34 denotes a spring receiver in which a large notch is formed so as not to prevent the passage of the refrigerant.
[0040]
A pressure receiving piston 35 that receives the pressure (Pd) of the discharge chamber 4 and the pressure (Ps) of the suction chamber 3 from both the front and back surfaces is connected to the valve body 32, and the pressure (Pd) of the discharge chamber 4 and the suction chamber 3 In a state where the pressure difference (Pd−Ps) with respect to the pressure (Ps) is larger than a certain level, the valve body 32 is separated from the valve seat 31 and the suction passage opening / closing valve 30 is opened, and the minimum operation state is entered and the pressure difference (Pd When -Ps) becomes smaller than a certain value, the valve body 32 is pressed against the valve seat 31 and the suction passage opening / closing valve 30 is closed.
[0041]
In this way, since the low-pressure refrigerant in the suction pipe 1 is not sucked into the compressor 10 during the minimum operation, it is possible to prevent the fins of the evaporator from freezing during the minimum operation when the load is small as in winter. it can.
[0042]
【The invention's effect】
According to the present invention, the variable displacement compressor maintains the minimum discharge amount in the variable range in a state where the electromagnetic control valve is not energized, so that the compressor is not operated. A clutch is not required, and the apparatus cost can be greatly reduced.
[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 capacity control solenoid valve according to the related art of the present invention.
FIG. 3 is a longitudinal sectional view showing the overall configuration of a compression capacity control device for a refrigeration cycle according to a second embodiment of the present invention.
[Explanation of symbols]
1 Suction line 2 Discharge line 3 Suction chamber 4 Discharge chamber 10 Compressor (variable capacity compressor)
12 Crank chamber (pressure regulating chamber)
14 Oscillating plate 19 Minimum securing spring 20 Capacity control solenoid valve (electromagnetic control valve)
27, 28 Compression coil spring 30 Suction path on-off valve

Claims (2)

The refrigerant sucked from the suction chamber leading to the suction pipe is compressed and discharged to the discharge chamber leading to the discharge pipe, and the discharge amount of the refrigerant is changed by the pressure change of the pressure regulating chamber pressure-controlled by the electromagnetic control valve. In the compression capacity control device of the refrigeration cycle having the variable capacity compressor,
The electromagnetic control valve, so as to maintain the differential pressure between the pressure of the pressure and the discharge chamber of the pressure regulating chamber to a predetermined pressure difference, by communicating and occlusion between said pressure regulating chamber and the discharge chamber A valve for changing the pressure in the pressure regulating chamber and changing the predetermined differential pressure by changing an electromagnetic force, and further communicating and closing the pressure regulating chamber and the discharge chamber. A first spring that biases the body in the valve closing direction, and a second spring that is arranged to bias the valve body in the valve opening direction and has a larger biasing force than the first spring, A compression capacity control device for a refrigeration cycle, wherein the valve body is maintained in an open state when no power is supplied so that the variable capacity compressor is in a minimum discharge amount range of a variable range. 2. The compression capacity of the refrigeration cycle according to claim 1, further comprising a suction passage opening / closing valve that closes between the suction pipe and the suction chamber when a differential pressure between the discharge chamber and the suction chamber becomes a predetermined value or less. Control device.

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