JPH0333531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a compressor for a vehicle air conditioner.

Generally, engine power is transmitted from a pulley to a compressor via an electromagnetic clutch, and the compressor acts as a load for the engine. Particularly when the engine accelerates or climbs a hill, the load on the compressor becomes a hindrance, making it difficult to accelerate, climb a hill, etc., so when accelerating or climbing a hill, the electromagnetic clutch is turned off to stop the compressor. However, with this type of control method, the compressor is completely stopped, which impairs the cooling performance, eliminates the ability to dehumidify and remove fog from the inside of the window glass, and causes the electromagnetic clutch to engage frequently. It has the disadvantage that it has an effect on its lifespan because it is controlled on and off.

Therefore, as shown in Japanese Patent Application Laid-Open No. 57-195884, the capacity of the compressor is controlled to be reduced as the engine speed increases during acceleration and hill climbing.
It has been proposed to drive the compressor at a small capacity when the engine rotates at high speed to eliminate the above drawbacks.
The capacity of the compressor can be adjusted by providing a pipe that bypasses any compression chamber of the compressor and the refrigerant inlet and adjusting the flow rate of the refrigerant in this pipe, or if the compressor is a swash plate type. There is a way to adjust the inclination angle of the swash plate. All of these are controlled to reduce the amount of refrigerant input to the compressor so as to substantially reduce the capacity of the compressor.

However, according to this method, since the compressor is rotated at a small capacity, cooling performance is not impaired and dehumidification is also possible, but when the compressor is rotating at high speed, the capacity of the compressor is set to be smaller than necessary. There is also a possibility that the compressor may seize. In other words, as the rotational speed of the compressor increases, the amount of refrigerant decreases, and the lubricating oil contained in the refrigerant is not sufficiently returned to the compressor side, resulting in less lubricating oil between the compressor shaft and bearing, resulting in increased friction. In particular, the lubrication between the shaft and bearing is carried out in a boundary layer consisting of a monomolecular layer or several molecular layers of lubricating oil, that is, boundary friction.
There is a dry friction area where lubricating oil molecules are not present, and this increases rapidly due to heat generation in the bearing part due to increased speed, and this reaches the entire bearing surface, causing seizure. Put it away.
Furthermore, since the amount of lubricating oil is not sufficient, the viscosity of the lubricating oil decreases, further increasing friction, leading to seizure.

An object of the present invention is to provide a control device that reduces the capacity of a compressor as the engine speed increases, so that once the engine speed reaches a predetermined speed, the compressor capacity is not reduced thereafter. This method secures the supply of refrigerant, that is, lubricating oil, and eliminates the above drawbacks, and will be described in detail below using examples.

FIG. 1 is a block diagram showing an embodiment of a control device for a compressor for a vehicle air conditioner according to the present invention, and in the figure, 1 is an air conditioner;
This includes an inside/outside air switching door 3 driven by an actuator 2, a blower 5 whose rotation speed is controlled by a drive circuit 4, an evaporator 7 cooled by a cooling cycle 6, a heater core 8, and a cold air and warm air blower 5. The actuator 9 adjusts the mixing ratio with the wind.
The system is comprised of an air mix door 10 controlled by an actuator, mode switching doors 13 and 14 controlled by actuators 11 and 12, and a cooling water cycle 15 that guides engine cooling water to the heater core 8.
The cooling cycle 6 includes a compressor 18 to which engine torque is transmitted via a pulley 16 and an electromagnetic clutch 17, a condenser 19, and a liquid receiver 20.
and an expansion valve 21. 30 is a control device for the compressor, which is connected to an internal air sensor 31.
The vehicle interior temperature tr detected by the outside air sensor 32
Thermal load detection means detects the magnitude of the heat load by calculating the outside air temperature ta detected by , and the set temperature TD of the temperature setting device 33 provided on the control panel (not shown).For example, TD-(tr+ta) is calculated. 34, and based on the magnitude of the signal to from this thermal load detection means, the drive circuit 35,
4, 36, 37, 38, the various switching doors 3, 13, 14, the air mix door 10, the blower 5, etc. are controlled to automatically perform air conditioning.

In the present invention, a capacity adjustment means 39 for adjusting the capacity of the compressor 18 is provided, and this capacity adjustment means 39 is automatically controlled by a control device 30. In FIG. The configuration of is shown in detail. The control device 30 includes an engine or compressor rotation sensor 24.
A signal R is supplied from a rotation speed detection means 40 which detects a signal from the engine and detects the rotation speed thereof. The signal R corresponding to the rotation speed of the engine or compressor output from the rotation speed detection means 40 and the signal to corresponding to the heat load output from the heat load detection means 34 are supplied to the capacity setting means 41,
The signal 41a from the capacitance setting means 41 is supplied to the capacitance adjusting means 39 via the selection means 42 and the drive circuit 45. The control device 30 is provided with an allowable minimum capacity setting means 43, and a signal 43a from the allowable minimum capacity setting means 43 is sent to the rotation speed detecting means 4.
This signal 43a is a signal having a magnitude related to the signal R output from 0, and is selected by the selection means 42, and is supplied from the selection means 42 to the capacitance adjustment means 39 via the drive circuit 45. Further, the output signal 41a from the capacity setting means 41 and the output signal 43a from the minimum allowable capacity setting means 43 are compared and judged by the comparison judgment means 44, and when the output signal 43a becomes larger than the output signal 41a, By controlling the selection means 42, this selection means 42
is the output signal 43 from the allowable minimum capacity setting means 43
Select a and drive circuit 45 and capacity adjustment means 39
It operates to output to .

To outline the operation of the compressor control device with the above configuration, the capacity setting means 41 is configured to reduce the capacity of the compressor as the rotational speed of the compressor or engine increases, as shown by characteristic P in FIG. to control. As a result, the capacity of the compressor decreases as the rotational speed of the compressor or engine increases, which reduces the load on the engine and allows smooth acceleration and hill climbing. Moreover, the cooling performance is not impaired, dehumidification can be performed, and wear of the electromagnetic clutch can be reduced. On the other hand, the allowable minimum capacity setting means 43 is the second
The compressor capacity is controlled to gradually increase as the engine speed increases, as shown in the diagram characteristic S. When the characteristic P is larger than the characteristic S by the comparison judgment means 44, that is, when the output signal 41a is larger than the output signal 43a, the characteristic P is selected and the capacity adjustment means 39 is controlled, and the predetermined rotation speed RO is When the characteristic S becomes larger than the characteristic P, the characteristic S is selected and the capacity adjusting means 39 is controlled by the characteristic S. That is, the control of the compressor by the capacity setting means 41 is switched to the control by the minimum allowable capacity setting means 43. By doing so, when the rotational speed of the compressor or the engine exceeds the predetermined rotational speed RO, the capacity of the compressor does not become small, so that the shortage of refrigerant, that is, the shortage of lubricating oil can be compensated for.

The capacity adjusting means 39 may be provided with a pipe that bypasses any compression chamber of the compressor and the refrigerant inlet, and may be an adjustment mechanism that adjusts the flow rate of the refrigerant in this pipe, or, if the compressor is of a swash plate type, adjusts the inclination angle of the swash plate. It may be composed of an adjustment mechanism etc. for adjustment,
In this embodiment, this capacity adjustment means is controlled by a motor 66, which will be described later. The heat load detection means 34, the rotation speed detection means 40, the capacity setting means 41, the selection means 4
2. Minimum allowable capacity setting means 43, comparison and determination means 4
4. The drive circuit 45 is constructed as shown in FIG. In FIG. 3, the heat load detection means 34 is connected to the inside air sensor 3 which is inputted via the multiplexer 46.
1. Temperature from outside air sensor 32 and temperature setting device 33
It has a calculation means 25 which outputs a signal to corresponding to the heat load as shown in FIG. 4 by calculating signals corresponding to tr, ta, and TD.
A differential amplifier 41m constituting the capacitance setting means 41
Supplied to the positive input side of the The rotation speed detection means 40 includes a waveform shaping circuit 47 that shapes the pulse output from the rotation sensor 24 provided in the compressor, and a frequency-voltage conversion circuit 48 that converts the pulse frequency output from the waveform shaping circuit 47 into a voltage value. It consists of The frequency-voltage conversion circuit 48 includes diodes 49, 50, 51 and capacitors 52, 5.
3, 54 and resistors 55, 56, 57, 58, 5
9, 60, etc., and this output signal R corresponds to the rotation speed of the compressor.
is supplied to the negative input side of the differential amplifier 41m. Output signal 41a from the capacity setting means 41
As shown by the characteristic P in FIG. 2, changes in inverse proportion to the magnitude of the thermal load signal to as the compressor rotational speed increases.

The output terminal 61 of the rotation speed detection means 40 is connected to the resistors 62 and 6 constituting the minimum allowable capacity setting means 43.
3, which is grounded through resistors 62 and 63.
The signal 43a obtained from the output terminal 64 connected to the connection point is a divided voltage of the signal R, and as shown in FIG. 5, the signal 43a is a certain percentage smaller than the signal R. The signal 43a outputted from the output terminal 64 is supplied to the other terminal of the selection means 42.

The output signal 41a from the capacitance setting means 41 is supplied to the negative input side of a comparator 65 constituting the comparison and determination means 44, and the output signal 43a output from the terminal 64 is supplied to the positive input side of the comparator 65. The output signal Vz of the comparison/judgment means 44 is
is set to L level when 41a>43a, so that the selection means 42 selects the input signal 41a, and 4
When 1a<43a, it becomes H level and the selection means 4
2 selects the input signal 43a.

The drive circuit 45 has a motor 66 for adjusting the valve of the capacity adjusting means 39, for example, for adjusting the flow rate of the refrigerant, or the inclination angle of the swash plate of the swash plate compressor. It is rotated in the forward direction by the current I to increase the capacity of the compressor, and by the current in the opposite direction, the capacity of the compressor is set to be small. One end of this motor 66 is connected to the collector side of a PNP type transistor 67 and also to the collector side of an NPN type transistor 68, and the other end is connected to the collector side of a PNP type transistor 69.
It is connected to the collector side of the NPN transistor 70. The emitter side of the transistor 67 is connected to the power supply, the base side is connected to the collector side of the transistor 72 via a resistor 71, and the base side of the transistor 68 is connected to the collector side of the transistor 72 via a resistor 73. Ru. The output terminal of a comparator 74 is connected to the base side of the transistor 72 via a resistor 75. The emitter side of the transistor 69 is connected to the power supply, and the base side is connected to the transistor 7 through a resistor 76.
7, the emitter side of the transistor 70 is grounded, and the base side is connected to the resistor 7.
8 to the collector side of the transistor 77. The output terminal of a comparator 79 is connected to the base side of the transistor 77 via a resistor 80. In this case, the output voltage Vy from the selection means 42
That is, the output signal 41a or the output signal 43a is supplied to the negative input side of the comparator 79 via the resistor 81, and is also supplied to the positive input side of the comparator 74 via the resistor 82. Also, the voltage at the connection point between the resistor 83 and the variable resistor 84 linked to the motor 66 is
The magnitude of Vx changes depending on the rotational position of the motor 66, that is, the capacity of the compressor, and the output voltage Vx of the variable resistor 84 is supplied to the positive input side of the comparator 79 via the resistor 85. , are supplied to the negative input side of the comparator 74 via the resistor 86. The drive circuit 45 outputs an output voltage to the above output voltage Vy.
The position of the motor 66 is controlled by rotating the motor 66 forward or reverse so that Vx always matches. for example
When Vy > Vx, the output of comparator 79 is at L level,
The output of comparator 74 becomes H level, transistor 77 is turned off, transistor 69 is turned off, and transistor 70 is turned on. Also, transistor 7
2 is turned on, transistor 67 is turned on, and transistor 68 is turned off. That is, transistor 6
Since both 7 and 70 are turned on, current I flows,
The motor 66 is rotated forward to increase the capacity of the compressor. At this time, the signal Vx increases and matches Vy, and this operation is stopped. Contrary to the above, Vx
>Vy, transistors 69 and 68 turn on,
Since transistors 71 and 70 are turned off, motor 6
Since a current in the opposite direction to the current I flows through the motor 66, the motor 66 lowers the capacity of the compressor.
At this time, the signal Vx becomes smaller and matches Vy, and this operation is stopped. In this way, the drive circuit 45 drives the motor 6 so that the signal Vx becomes equal to the signal Vy.
Rotate 6 forward and reverse. Note that a certain amount of hysteresis is provided to the comparators 79 and 74 in order to prevent a hunting condition from occurring due to alternating forward and reverse rotations.

2 and 4 regarding the operation of the control device for a vehicle air conditioner compressor with the above configuration.
This will be explained below using the characteristic diagrams shown in FIGS.
First, the heat load detection means 34 calculates the difference between the set temperature TD of the temperature setting device 33, the vehicle interior temperature tr detected by the inside air sensor 31, and the outside air temperature ta detected by the outside air sensor 32, and calculates the difference corresponding to this difference. The signal, that is, the thermal load signal to, is outputted to the positive input side of the differential amplifier 41m constituting the capacitance setting means 41. On the other hand, a signal R corresponding to the rotation speed of the compressor output from the output terminal 61 of the rotation speed detection means 40 is supplied to the negative input side of the differential amplifier 41m of the capacity setting means 41. The capacity of the compressor is set by the output signal 41a of the capacity setting means 41, and based on this output signal 41a, the capacity of the compressor is determined by the number of revolutions of the compressor relative to the heat load, as shown in the characteristic P in Figure 2. is controlled to gradually become smaller as the speed increases. Next, the output signal 43a of the output terminal 64 of the allowable minimum capacity setting means 43 becomes smaller by a certain percentage with respect to the output signal R of the rotation speed detection means 40, as shown in FIG. It changes in size as it gradually increases,
This output signal 43a is supplied to the other terminal of the selection means 42. Here, if the rotational speed of the compressor has not reached RO, the relationship between the signals 41a and 43a is 41a>43a, so the output voltage Vz of the comparison/judgment means 44 becomes L level, and the selection means 42 selects the signal 41a. Select drive circuit 4
Supply to 5. Therefore, the capacity of the compressor is controlled based on the characteristic P, and the capacity is controlled to become smaller as the rotational speed of the compressor increases. As a result, the engine speed increases, and when the compressor speed increases, the compressor capacity is set to a smaller value, which reduces the load on the engine and allows smooth acceleration and hill climbing. can. Next, when the rotation speed of the compressor exceeds the predetermined rotation speed RO, the output signal 41a
Since the relationship between and 43a is 43a>41a, the output voltage Vz of the comparison and determination means 44 becomes H level,
The selection means 42 operates to select the signal 43a. For this purpose, the compressor is controlled according to the characteristic S shown in FIG. As a result, after RO, the engine speed increases, and as the compressor speed increases, the capacity of the compressor gradually increases, and the rate of increase is relatively slow. As a result, the amount of refrigerant returned to the compressor is not insufficient and the lubricating oil is not insufficient, the bearing portion is not heated, a sufficient lubricating oil film is formed, and the viscosity of the lubricating oil film is not reduced, so seizure can be prevented.

FIG. 6 is a circuit diagram showing another embodiment of the control device for a compressor for a vehicle air conditioner according to the present invention, and the same parts as in FIG. 3 are designated by the same reference numerals. In this case, 87 is an electromagnetic clutch control means, which is incorporated into the control device 30, for example. The electromagnetic clutch 17 is turned off when the temperature of the evaporator 7 drops close to the freezing temperature, and turned on when it rises above that temperature to keep the temperature of the evaporator 7 constant. The output signal of this electromagnetic clutch control means 87 is supplied to the base side of a transistor 89 connected to a relay 88. Contact 88a of the relay 88
are connected in series to the electromagnetic clutch 17. here,
For example, when the ignition switch 22 and the air conditioner switch 23 are both on, the output signal of the electromagnetic clutch control means 87 becomes H level,
When transistor 89 is turned on, relay 88 is energized, contact 88a is turned on, electromagnetic clutch 17 is driven, and the compressor is turned on. When transistor 89 turns off, the compressor turns off. The rotational speed signal R output from the output terminal 61 of the rotational speed detection means 40 is supplied to the positive input side of a comparator 90 constituting the compressor protection means 28, and a resistor 91 is connected to the negative input side of the comparator 90. and 9
2 and a divided reference voltage Vf is supplied. This voltage Vf is set to a voltage corresponding to a value slightly larger than approximately zero of the rotation speed of the compressor, and the output of the comparator 90 is determined when the compressor stops and the output signal R of the rotation speed detection means 40 reaches zero. R＜Vf
When the relationship is established, the level becomes L level. Comparator 9
The output side of the transistor 95 is connected to the base side of the transistor 95 via a resistor 93 and a diode 94, and the emitter side of the transistor 95 is connected to the base side of the transistor 89 via a resistor 96. 97
is a monostable circuit, and the output terminal side has a resistor 9
8. Connected to the base side of the transistor 95 via a diode 99. When the output of the comparator 90 is at the H level, the transistor 95 is off, so the transistor 89 is controlled on/off by the output signal of the electromagnetic clutch control means 87, but the output of the comparator 90 changes from the H level to the L level. When it is reversed, transistor 95 turns on, so transistor 8
9 is pulled down to ground potential, which turns transistor 89 off, turning off electromagnetic clutch 17 and stopping the compressor. The monostable circuit 97 outputs a pulse 97a of a constant width from the output terminal when the ignition switch 22 and the air conditioner switch 23 are turned on.
Since the transistor 95 is kept on for the duration of the pulse width of the pulse 97a, the air conditioner switch turns on the transistor 89, turns on the relay 88, turns on the contact 88a, turns on the magnetic clutch 17, and the compressor rotation rises to a predetermined value. Since the compressor is turned on regardless of the output of the comparator 90 until then, malfunctions immediately after the air conditioner is switched on can be prevented.

The operation of the control device for a vehicle air conditioner compressor having the above configuration will be described below.
When both the ignition switch 22 and the air conditioner switch 23 are on and the compressor is normal, the output signal R of the rotational speed detection means 40 is greater than zero, so the output of the comparator 90 becomes H level, which causes the compressor to Electromagnetic clutch control means 8
7, and its capacity is controlled by the capacity setting means 41 or the minimum allowable capacity setting means 43, as described above.

Here, if the compressor burns out for some reason, the output signal R of the rotation speed detection means 40 becomes zero, and the output of the comparator 90 is inverted from H level to L level, so that the transistor 9
5 is turned on, transistor 89 is turned off, and the compressor is held stopped. Therefore, when the compressor seizes and becomes locked, power from the engine is not transmitted, thereby preventing accidents such as belt breakage. FIG. 7 is a circuit diagram showing another embodiment of the control device for a compressor for a vehicle air conditioner according to the present invention, and the same parts as in FIG. 3 are denoted by the same reference numerals. In this embodiment, a sensor 100 is provided to detect the temperature of the refrigerant in the cooling cycle 6 or the temperature of various cooling devices such as a compressor, evaporator, and liquid receiver. Differential amplifier 102 constituting control means 108
The output signal R of the rotation speed detection means 40 is supplied to the positive input side of the differential amplifier 102 via the resistor 103, and the output signal 43a of the differential amplifier 102 is supplied to the negative input side of the differential amplifier 102. Similarly, the signal is supplied to the other input side of the selection means 42. As a result, when the refrigerant temperature rises due to refrigerant shortage, as shown by arrow M in FIG. It can be made larger and can compensate for refrigerant shortages. In other words, even if the capacity of the compressor is uniformly controlled in the mode shown by characteristic S in Fig. 2, if a refrigerant shortage occurs depending on the cooling state of the evaporator, etc., the compressor is controlled by capacity according to characteristic S. However, according to this embodiment, even such a refrigerant shortage can be compensated for.

FIG. 9 is a circuit diagram showing another embodiment of the control device for a compressor for a vehicle air conditioner according to the present invention, and the same parts as in FIG. 7 are designated by the same reference numerals. The difference from FIG. 7 is that a sensor 104 for detecting the amount of refrigerant is provided instead of the sensor 100. The sensor 104 may be configured to detect the gas pressure of the refrigerant, the capacitance in the pipe, or the number of bubbles of the refrigerant in the liquid receiver. In this case, the differential amplifier 102 constitutes a refrigerant amount control means. In such a configuration, when a refrigerant shortage occurs, the resistance value of the sensor 104 decreases, and the output signal 43a can be shifted to a larger value as shown by the arrow M as in the case of FIG. 7, thereby compensating for the refrigerant shortage. be able to. That is, more precise capacity control can be performed.

In the present invention, the rotation speed of the compressor is detected and the capacity of the compressor is controlled based on the rotation speed of the compressor. However, the present invention is not limited to this, and as shown in FIG. Pulses output in synchronization with the engine speed from between an inductance coil 106 branched off from an isoductance coil 105 connected to the user and a point 107 are supplied to a frequency-voltage conversion circuit 48 to convert the engine. A signal corresponding to the rotational speed of the compressor may be taken out from the terminal 61, and the capacity of the compressor may be controlled in accordance with the characteristic P based on this signal.

In addition, in the present invention, the capacity of the compressor is controlled to be reduced as shown by characteristic P when the rotation speed of the compressor or engine increases with respect to the heat load, so even if the rotation speed of the compressor is high, the heat load can be reduced. When it is large, the capacity of the compressor does not become extremely small and cooling performance can be ensured.

As explained above, the control device for a compressor for a vehicle air conditioner according to the present invention includes a rotation speed detection means for detecting the rotation speed of the engine or the compressor, and a rotation speed detection means for detecting the rotation speed of the engine or the compressor, and a control device for controlling the compressor based on the output signal from the rotation speed detection means. capacity setting means for controlling the capacity of the compressor and setting the capacity of the compressor to be small when the rotation speed of the compressor or the engine increases;
A minimum permissible capacity setting means for setting the minimum capacity of the compressor to a capacity that does not cause lubrication failure due to lack of refrigerant, and a control by the compressor capacity setting means when the rotation speed of the compressor or engine reaches a predetermined rotation speed RO. , and a selection means for switching to the control of the above-mentioned minimum allowable capacity setting means, so that the capacity of the compressor can be set to the minimum capacity that does not cause lubrication failure. Seizure of rotating friction parts can be reliably prevented. Further, it is possible to prevent a decrease in the viscosity of the lubricating oil, thereby preventing seizure due to poor lubrication.

In addition, by finely adjusting the allowable minimum capacity setting means based on the temperature of the refrigerant or the equipment through which this refrigerant flows back, or by detecting the amount of refrigerant and making fine adjustments based on this detected value, more accurate capacity can be determined. can be controlled and seizure can be reliably prevented.

In addition, as a means of setting the minimum allowable capacity, ROM
The compressor capacity may be controlled based on the read data by reading out the stored value corresponding to the characteristic S in accordance with the rotational speed of the compressor or engine. In short, it is sufficient to output data that is related to the rotational speed of the compressor or engine and that allows the capacity of the compressor to be set to the minimum capacity that does not cause poor lubrication.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a control device for a compressor for a vehicle air conditioner according to the present invention, and FIG. 2 is a characteristic diagram for explaining its operation.
FIG. 3 is a circuit diagram showing a specific circuit of a control device for a compressor for a vehicle air conditioner according to the present invention;
4 and 5 are characteristic diagrams for explaining its operation, and FIGS. 6, 7, 9, and 10 show other control devices for a compressor for a vehicle air conditioner according to the present invention. A circuit diagram showing an example, FIG.
FIG. 9 is a characteristic diagram for explaining the operation of the control device for the compressor for a vehicle air conditioner explained in FIGS. 1...Vehicle air conditioner, 3...Inside/outside air switching door, 5...Blower, 7...Evaporator, 8...
Heater core, 10...Air mix door, 13,
14...Mode switching door, 17...Electromagnetic clutch, 18...Compressor, 30...Control device,
31... Inside air sensor, 32... Outside air sensor, 33
... Temperature setting device, 34 ... Heat load detection means, 39
... Capacity adjustment means, 41 ... Capacity setting means, 42
... selection means, 43 ... allowable minimum capacity setting means,
44... Comparison/judgment means, 100, 104... Sensor.

Claims (1)

[Claims] 1. A rotation speed detection means for detecting the rotation speed of the compressor or the engine, and a capacity of the compressor is set based on an output signal from the rotation speed detection means, and the rotation speed of the compressor or the engine is increased. a capacity setting means for setting the capacity of the compressor to a smaller value as the compressor increases, a permissible minimum capacity setting means for setting the capacity of the compressor to a minimum capacity that does not cause lubrication failure due to insufficient refrigerant in the compressor; A compressor for a vehicle air conditioner, comprising a selection means for switching the compressor control by the capacity setting means to the compressor control by the minimum allowable capacity setting means when the number of rotations reaches a predetermined number of revolutions. Control device. 2. A rotation speed detection means for detecting the rotation speed of the compressor or engine, and a capacity of the compressor is set based on an output signal from the rotation speed detection means, and as the rotation speed of the compressor or engine increases, the capacity of the compressor is set. capacity setting means for setting the capacity to a small capacity; allowable minimum capacity setting means for setting the capacity of the compressor to a minimum capacity that does not cause lubrication failure due to insufficient refrigerant in the compressor; a selection means for switching the control of the compressor by the capacity setting means to the control of the compressor by the minimum allowable capacity setting means, and detecting the temperature of the refrigerant or the cooling equipment through which this refrigerant flows back; 1. A control device for a compressor for a vehicle air conditioner, comprising temperature control means that controls a setting means to increase the capacity of the compressor when the temperature rises. 3 A rotation speed detection means for detecting the rotation speed of the compressor or engine, and a capacity of the compressor is set based on an output signal from the rotation speed detection means, and as the rotation speed of the compressor or engine increases, the capacity of the compressor is set. capacity setting means for setting the capacity to a small capacity; allowable minimum capacity setting means for setting the capacity of the compressor to a minimum capacity that does not cause lubrication failure due to insufficient refrigerant in the compressor; selection means for switching the control of the compressor by the capacity setting means to the control of the compressor by the minimum allowable capacity setting means when the minimum allowable capacity setting means is reached; 1. A control device for a compressor for a vehicle air conditioner, comprising a refrigerant amount control means for increasing the capacity of the compressor when the amount of refrigerant is low.