JP2001121952A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner for a vehicle having little fluctuation in brow-off air temperature and a torque shock and capable of improving amenity. SOLUTION: This air conditioner includes a refrigerant circuit having a variable displacement compressor and an interior heat provided in a ventilating duct, a capability target value setting means for setting the target value of temperature indicating the heat exchange capability of the refrigerant circuit, a refrigerant circuit operating condition detecting means for detecting the operating condition of the refrigerant circuit, and a control means for controlling the compressor capacity to control the temperature indicating the heat exchange capability to the target value. In the air conditioner, the control means performs two-position control for the compressor capacity between the control capacity value when it reaches a first or a second set value range and a predetermined small control capacity value smaller than the control capacity value corresponding to a first set value set for the operating condition amount of the refrigerant circuit for the excessive control limit of the compressor capacity and a second set value higher than the first set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a vehicle, and more particularly, to a variable displacement compressor in which the on-off control of a conventional fixed displacement compressor is used and the capacity of the compressor is changed to a heat exchange capacity. 2 representing the temperature and the operating state quantity of the refrigerant circuit
TECHNICAL FIELD The present invention relates to an air conditioner for a vehicle, which is controlled by using one of them, has less fluctuation in blown air temperature and torque shock, and has improved comfort.

[0002]

2. Description of the Related Art A conventional vehicle air conditioner is shown in FIG.
12 are configured as shown in FIG. FIG. 8 shows an example of a cooling cycle. In FIG.
Denotes an entire vehicle air conditioner, and an inside / outside air switching damper 1 is provided on the upstream side in a ventilation duct 102 opening into the vehicle interior.
A blower 106 for pressure-feeding the intake air from the outside air introduction port 104 and the inside air introduction port 105 adjusted by 03 is provided. An evaporator 107 as an indoor heat exchanger for cooling the blown air is provided downstream of the blower 106, and a hot water heater 10 as a heater is provided downstream thereof.
8 are provided. The engine coolant is circulated through the hot water heater 108. An air mix damper 110 whose opening is adjusted by an air mix damper actuator 109 is disposed immediately downstream of the hot water heater 108. The temperature-controlled air is supplied to the dampers 111 and 11.
The air is blown into the vehicle interior through air outlets 114, 115, 116 provided with 2, 113.

[0003] Reference numeral 117 denotes a refrigerant circuit in which each device is connected via a refrigerant pipe, and reference numeral 118 denotes a fixed displacement compressor (fixed displacement compressor). Compressor 118
The refrigerant compressed by the evaporator 107 is sent to the evaporator 107 through the condenser 119, the liquid receiver 120, and the expansion valve 121,
The refrigerant from 7 is sucked into the compressor 118. In this example, the compressor 118 is driven via the clutch 122,
The operation of the clutch 122 is controlled by a clutch control relay 123. A clutch control signal is sent from the main controller 124 to the clutch control relay 123. The main controller 124 receives a setting signal of the target vehicle interior temperature from the vehicle interior temperature setting device 125. Further, a signal is sent from the main controller 124 to the blower voltage controller 126 so that the blower 10
6 is controlled. Further, a vehicle interior temperature sensor 127, a solar radiation sensor 128, and an outside air temperature sensor 129 are provided.
Are input to the main controller 124. In addition, a throttle opening signal, an engine speed signal, and the like are input to the main controller 124 from the engine ECU 130.

In the main controller 124, for example, control as shown in FIG. 9 is performed. The signal of the target vehicle temperature Trs set by the vehicle temperature setting device 125, the solar radiation amount RAD detected by the solar radiation sensor 128, the vehicle interior temperature TR detected by the vehicle interior temperature sensor 127, and the outdoor temperature detected by the outdoor temperature sensor 129. AMB
Is calculated from the following signals by the following equation. TOs = Kp1 (TR−Trs) + f (AMB, RA
D, Trs) Kp1 is a coefficient.

Using the calculated target outlet temperature TOs,
Blower voltage BLV corresponding to the blower volume of the blower is calculated by BLV = f (TOs). The calculated BLV signal is sent to the blower voltage controller 126.

[0006] The air mix damper opening AMD is calculated by AMD = f (TOs, TW, TV). TW is the engine cooling water temperature at the inlet of the hot water heater 8, and TV is the evaporator outlet air temperature target value.
The calculated AMD signal is sent to the air mix damper actuator 109.

[0007] The evaporator outlet air temperature target value TV is calculated from the outside air temperature AMB by the following equation: TV = a · AMB + b. a and b are constants.

The clutch control signal of the compressor is calculated (determined) under the following conditions, for example. Evaporator (cooler) outlet air temperature target value TV and evaporator outlet air temperature Te
And Te> TV + 1 as shown in FIG.
Is a clutch-on condition, and Te <TV-1 is a clutch-off condition. This clutch control signal is sent to the clutch controller (clutch control relay 123).

FIG. 11 shows an example of a heating cycle. In the vehicle air conditioner 141 shown in FIG. 11, a condenser 142 as an indoor heat exchanger for heating the air to be blown is provided in the ventilation duct 102,
An evaporator 143 is provided as an outdoor heat exchanger. The other configuration is substantially the same as the configuration shown in FIG.
FIG. 12 shows the control. The control is substantially the same as the control shown in FIG. 9 except that the clutch control of the compressor is performed based on the calculated value of the condenser outlet air temperature target value TV and the condenser outlet air temperature Te. It is performed in the same way.

In the conventional vehicle air conditioner as described above, a combination of a fixed displacement compressor + clutch cycling + mechanical pressure switch is used.
If the high-pressure pressure in the circuit becomes abnormally high due to an abnormality or failure in the refrigeration circuit and exceeds a set limit value, if the operation is continued as it is, the cause of failure or breakage of parts in the circuit Therefore, by turning off the pressure switch (or turning on the pressure switch), the clutch is turned off, and the compressor is stopped, thereby ensuring the safety of the equipment in the refrigeration circuit. That is, for example, control as shown in FIG. 13 was performed.

Further, other than the high pressure, the following control is performed. For example, in a cooling cycle,
Discharge gas temperature, discharge gas superheat (SH),
Control to stop the compressor when the compressor body temperature rises,
In the heating cycle, control to stop the compressor when the suction pressure becomes low, or control to stop the compressor when the temperature of the discharge gas or the temperature of the compressor body becomes high is performed. In each case, the compressor is stopped to prevent compressor damage.

[0012]

However, in the conventional control method as described above, the clutch is repeatedly turned on and off (that is, the capacity of the compressor is maximum and the capacity is zero) depending on the value of the pressure or the like. For the driver, a torque shock caused by the on / off of the clutch was to occur.

In the clutch control, too frequent detachment cannot be performed because of the durability of the clutch and the control relay and the detachment noise. Therefore, the operating point is set so that the ON / OFF cycle is activated in more than ten seconds.
Since the off cycle is long, there is also a problem that the temperature of the blown air fluctuates. Since there is a delay in the response of the blowout temperature to the change in the capacity of the compressor, when the ON / OFF cycle is short, the blowout temperature fluctuation is reduced.

Therefore, an object of the present invention is to replace on / off control by a fixed displacement compressor which has been widely used in the past,
By using a variable displacement compressor and controlling its capacity using two factors, the temperature representing the heat exchange capacity and the operating state quantity of the refrigerant circuit, there are less fluctuations in blown air temperature and torque shock, making it more comfortable. It is an object of the present invention to provide a vehicle air conditioner capable of improving performance.

[0015]

SUMMARY OF THE INVENTION In order to solve the above problems, an air conditioner for a vehicle according to the present invention comprises a variable displacement compressor capable of arbitrarily changing a discharge capacity in accordance with a capacity control signal, and a compressor in a ventilation duct. A refrigerant circuit including an indoor heat exchanger provided therein; capacity target value setting means for setting a target value of temperature representing a heat exchange capacity of the indoor heat exchanger; and refrigerant circuit operation for detecting an operation state of the refrigerant circuit. A vehicle comprising: a state detecting means; and a control means for controlling a compressor capacity based on information from the temperature detecting means and the refrigerant circuit operating state detecting means and controlling a temperature representing the heat exchange capacity to a target temperature. In the air conditioner, the control unit is configured to set a first set value and a second set value higher than the first set value for the operation state amount of the refrigerant circuit for limiting excessive control of the compressor capacity. And the pressure The two-position control of the machine capacity is performed between a control capacity value when the first or second set value range is reached and a predetermined small control capacity value smaller than the control capacity value. Consist of things.

In the vehicle air conditioner, when the indoor heat exchanger is a refrigerant evaporator (in a cooling cycle) and when the indoor heat exchanger is a refrigerant condenser (in a heating cycle), Applicable to both.

Further, in the vehicle air conditioner, the difference between the first set value and the second set value can be a predetermined constant value. Further, the small control capacity value of the compressor capacity can be set to the minimum capacity value of the variable capacity compressor.

The difference between the first set value and the second set value includes, for example, a compressor discharge pressure, a compressor discharge temperature,
It can be set for at least one of the compressor body temperatures. In this case, as a difference between the first set value and the second set value, the compressor discharge pressure is 0.2 MPa or less, the compressor discharge temperature is 5 ° C. or less, and the compressor body temperature is 5 ° C. or less. Preferably, it is set. By setting such a difference, it is possible to realize a control state in which the fluctuation of the blown air temperature and the torque shock are small.

As a difference between the first set value and the second set value, for example, at least one of a compressor suction pressure, a compressor discharge pressure, a compressor discharge temperature, and a compressor body temperature is set. be able to. In this case, as a difference between the first set value and the second set value, the compressor suction pressure is 0.04 MPa or less, the compressor discharge pressure is 0.2 MPa or less, and the compressor discharge temperature is 5 ° C. or less. The temperature of the compressor body is preferably set at 5 ° C. or less. By setting such a difference, it is possible to realize a control state in which the fluctuation of the blown air temperature and the torque shock are small.

The refrigerant circuit operating state detecting means includes:
It can be configured as a unit including a pressure sensor or a temperature sensor capable of continuously detecting pressure or temperature, or a unit including a pressure switch or a temperature switch.

In the vehicle air conditioner according to the present invention, the capacity of the variable displacement compressor is controlled by using the temperature of the evaporator (or condenser) outlet air and the refrigerant circuit state quantity. During normal control, the compressor capacity is controlled such that the evaporator (or condenser) outlet air temperature becomes a target value. When the refrigerant circuit state quantity is higher than a preset value, for example, the first set value, the capacity control value is controlled to control the state quantity to a limit value (for example, the second set value) or less. By controlling the position of the compressor (for example, the control current value of the displacement control valve) at two positions, the compressor is controlled so that the compressor displacement does not become excessively large while keeping the variation of the state quantity small. By this control, the fluctuation of the blown-out air temperature and the torque shock are suppressed to be small, and the comfort is further improved.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic equipment system diagram of a vehicle air conditioner according to one embodiment of the present invention, and shows a case of a device having a vapor compression refrigeration cycle (cooling cycle). In FIG. 1, reference numeral 1 denotes an entire vehicle air conditioner, and an upstream side inside a ventilation duct 2 opening into a vehicle interior is provided with an outside air inlet 4 and an inside air inlet 5 adjusted by an inside / outside air switching damper 3. A blower 6 for pressure-feeding the intake air is provided. An evaporator 7 as an indoor heat exchanger for cooling the blown air is provided downstream of the blower 6, and a hot water heater 8 as a heater is provided downstream thereof. The engine coolant is circulated through the hot water heater 8. An air mix damper 10 whose opening is adjusted by an air mix damper actuator 9 is disposed immediately downstream of the hot water heater 8. The temperature-controlled air is supplied to the dampers 11, 12, 1,
The air is blown into the passenger compartment through each of the air outlets 14, 15, 16 provided with 3.

Reference numeral 17 denotes a refrigerant circuit in which each device is connected via a refrigerant pipe, and reference numeral 18 denotes a variable displacement compressor (variable displacement compressor). The refrigerant compressed by the compressor 18 is supplied to the condenser 19, the liquid receiver 20, the expansion valve 2
1, the refrigerant is sent to the evaporator 7, and the refrigerant from the evaporator 7 is sucked into the compressor 18. In the present embodiment, the discharge pressure of the compressor 18 or the pressure corresponding thereto is detected by the discharge pressure sensor 22, and the discharge gas temperature (discharge gas superheat degree [SH]) is detected by the discharge gas temperature sensor 23. . The body temperature of the compressor 18 is detected by a body temperature sensor 24. Further, the outlet air temperature of the evaporator 7 is detected by the evaporator sensor 25. These detection signals are sent to the main controller 26.

The capacity control mechanism of the variable capacity compressor 18 first controls the crank chamber pressure by the gas flow rate passing through the valve, as described in, for example, JP-A-63-16177. The compressor swash plate angle is adjusted by the crankcase pressure. That is, compressor capacity control is performed by gas flow rate control using a valve.

The main controller 26 receives a set signal of a target vehicle temperature from a vehicle temperature setting device 27. Further, a signal is sent from the main controller 26 to the blower voltage controller 28, and the voltage (rotation speed) of the blower 6 is
Is controlled. In the present embodiment, detection signals from the vehicle interior temperature sensor 29, the solar radiation sensor 30, and the outside air temperature sensor 31 are input to the main controller 26, respectively. In addition, a throttle opening signal, an engine speed signal, and the like are input from the engine ECU 32 to the main controller 26.

FIG. 2 is a schematic equipment diagram of an air conditioner 41 for a vehicle according to another embodiment of the present invention, and shows a case of an apparatus having a vapor compression heat pump cycle (heating cycle). . Vehicle air conditioner 41 shown in FIG.
, A condenser 42 is provided as an indoor heat exchanger, and a condenser sensor 43 for detecting an outlet air temperature thereof.
And an evaporator 44 as an outdoor heat exchanger.
The configuration is substantially the same as the configuration shown in FIG.

In the main controller 26, the following control is performed. FIGS. 3 and 4 show control examples of the vehicle air conditioners 1 and 41 shown in FIGS.
Each is shown.

In the control shown in FIG. 3, a signal of the target vehicle interior temperature Trs set by the vehicle interior temperature setting device 27, the solar radiation amount RAD detected by the solar radiation sensor 30, and the vehicle interior temperature TR detected by the vehicle interior temperature sensor 29. From the signals of the outside air temperature AMB detected by the outside air temperature sensor 31, the target outlet temperature TOs is calculated by the following equation. TOs = Kp1 (TR−Trs) + f (AMB, RA
D, Trs) Kp1 is a coefficient.

Using the calculated target outlet temperature TOs,
Blower voltage BLV corresponding to the blower volume of the blower is calculated by BLV = f (TOs). The calculated BLV signal is sent to the blower voltage controller 28.

Further, the air mix damper opening degree AMD is calculated by AMD = f (TOs, TW, TV). TW is the engine cooling water temperature at the inlet of the hot water heater 8, and TV is the evaporator outlet air temperature target value.
The calculated AMD signal is sent to the air mix damper actuator 9.

The evaporator outlet air temperature target value TV is calculated from the outside air temperature AMB as follows: TV = a · AMB + b. a and b are constants.

The control of the capacity of the compressor is performed separately for evaporator outlet air temperature control and compressor (compressor) discharge pressure. First, at the time of the normal control, the capacity of the compressor is controlled so that the evaporator outlet air temperature Te is detected and the target temperature TV is obtained. That is, the control current value Icont of the displacement control valve is obtained by Icont = f (TV, Te).

Next, when the compressor discharge pressure exceeds a preset limit value, as shown in FIG. 5, the control current value of the displacement control valve is changed to Icont to control the pressure value to the limit value or less. And 0 are controlled. Where Ico
nt is the control current value immediately before exceeding the limit value, and 0 is the minimum displacement value of the variable displacement compressor.

In FIG. 5, A is the first set value relating to the refrigerant circuit state quantity referred to in the present invention, B is the second set value referred to in the present invention, and the compressor discharge pressure Pd, the compressor discharge gas temperature. Td or superheat degree of compressor discharge gas. H. Is set for each of the compressor body (body) temperatures Tb. Then, the control current value of the capacity control valve of the compressor is made to correspond to the first set value A and the second set value B, and when the state quantity exceeds the first set value, the compressor of the compressor is controlled. The capacitance control signal value is controlled at two positions between Icont and 0.
By this control, in principle, the refrigerant circuit state quantity does not exceed the second set value B as a limit value that is not desirably exceeded.

If the difference between the first set value A and the second set value B in the two-position control is set to be small, the fluctuation at the time of the two-position control can be kept very small, and at the same time, the state quantity can be reduced. The control is performed so as not to exceed the limit value and to prevent the capacity of the compressor from becoming excessive. Moreover, the two-position control relating to the capacity of the compressor is different from the on / off control in the conventional fixed displacement compressor,
Since the two-position control is performed with respect to the capacity in the continuous operation state of the compressor, a large torque shock does not occur with the control.

In the two-position control, if the difference between the first set value A and the second set value B is set small,
Fluctuation during the position control can be suppressed to a very small value.
2 MPa or less, more preferably 0.1 MPa or less, and the compressor discharge temperature is 5 ° C. or less, more preferably 1.5 ° C. or less.
C. or lower, and the compressor body temperature is preferably 5 C. or lower, more preferably 1.5 C. or lower.

By such control, in particular, the frequency of the torque shock which has been received when the compressor of the compressor is turned on is reduced. Further, by controlling the capacity of the compressor, a sudden change in the temperature of the blown-out air as in the related art is eliminated. In particular, if the difference between the first and second set values for controlling the variable capacity signal is reduced, torque fluctuation and air temperature fluctuation hardly occur.

Incidentally, in the apparatus shown in FIG. 1, FIGS.
When the control is performed in the following manner, compared with the conventional device (FIGS. 8 and 9),
As shown in FIG. 7, high pressure change, compressor torque change,
A great improvement was obtained for all changes in the outlet air temperature.

FIG. 4 shows the vehicle air conditioner 41 shown in FIG.
4 shows a control example regarding the above. In the control shown in FIG. 4, the target outlet temperature TOs and the blower voltage BLV are calculated in the same manner as in the above embodiment. The capacity control of the compressor
At the time of the normal control, the compressor outlet air temperature Tc is detected, and the displacement of the compressor is controlled so that it becomes the target value TV.
That is, the control current value Icont of the displacement control valve is obtained by Icont = f (TV, Tc).

Next, when the compressor discharge pressure exceeds a preset limit value, the control current value of the displacement control valve is changed to Icont as shown in FIG. And 0 are controlled. Where Ico
nt is the control current value immediately before exceeding the limit value, and 0 is the minimum displacement value of the variable displacement compressor.

In FIG. 6, C is the first set value relating to the refrigerant circuit state quantity referred to in the present invention, D is the second set value referred to in the present invention, and the compressor suction pressure Ps and the compressor discharge pressure Pd , The compressor discharge gas temperature Td or the compressor discharge gas superheat degree S. H. Is set for each of the compressor body (body) temperatures Tb. Then, the control current value of the capacity control valve of the compressor is made to correspond to the first set value C and the second set value D, and when the state quantity exceeds the first set value, the compressor is started. The capacitance control signal value is controlled at two positions between Icont and 0. By this control, in principle, the refrigerant circuit state quantity does not exceed the second set value D as a limit value that is not desirably exceeded.

If the difference between the first set value C and the second set value D in the two-position control is set to be small, the fluctuation at the time of the two-position control is extremely small, and at the same time, the state quantity is reduced. The control is performed so as not to exceed the limit value and to prevent the capacity of the compressor from becoming excessive. Moreover, the two-position control relating to the capacity of the compressor is different from the on / off control in the conventional fixed displacement compressor,
Since the two-position control is performed with respect to the capacity in the continuous operation state of the compressor, a large torque shock does not occur with the control.

In the two-position control, if the difference between the first set value C and the second set value D is set small,
Fluctuations during position control can be kept very small, but a preferable difference is, for example, about 0.1% for the compressor suction pressure.
04 MPa or less, more preferably 0.02 MPa or less,
The compressor discharge pressure is 0.2 MPa or less, more preferably 0.1 MPa or less, and the compressor discharge temperature is 5 MPa or less.
C. or lower, more preferably 1.5 ° C. or lower, and the compressor body temperature is preferably 5 ° C. or lower, more preferably 1.5 ° C. or lower.

By such control, in particular, the frequency of the torque shock conventionally received when the clutch of the compressor is turned on is reduced. Further, by controlling the capacity of the compressor, a sudden change in the temperature of the blown-out air as in the related art is eliminated. In particular, if the difference between the first and second set values for controlling the variable capacity signal is reduced, torque fluctuation and air temperature fluctuation hardly occur.

[0045]

As described above, according to the air conditioner for a vehicle according to the present invention, the variable displacement type compressor can be used by using the evaporator (or condenser) outlet air temperature and the refrigerant circuit state quantity. Since the displacement is controlled at two positions, a large variation in the compressor capacity can be suppressed while keeping the variation in the state quantity small, and in particular, the torque shock that has been received when the clutch of the compressor in the related art is turned on can be reduced. Further, by controlling the capacity of the compressor, a sudden change in the temperature of the blown air as in the related art is eliminated. In particular, if the difference between the first and second set values of the refrigerant circuit state quantity for controlling the variable capacity signal is reduced, torque fluctuation and air temperature fluctuation hardly occur.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a vehicle air conditioner according to another embodiment of the present invention.

FIG. 3 is a control block diagram of the vehicle air conditioner shown in FIG. 1;

FIG. 4 is a control block diagram of the vehicle air conditioner shown in FIG. 2;

FIG. 5 is a characteristic diagram showing an example of two-position control on a refrigerant circuit state quantity in control of the vehicle air conditioner shown in FIG. 3;

6 is a characteristic diagram showing an example of two-position control relating to a refrigerant circuit state quantity in control of the vehicle air conditioner shown in FIG. 4;

FIG. 7 is a characteristic diagram illustrating an example of an effect obtained by controlling the vehicle air conditioner illustrated in FIG. 3;

FIG. 8 is an overall configuration diagram of a conventional vehicle air conditioner.

9 is a control block diagram of the vehicle air conditioner shown in FIG.

FIG. 10 is a characteristic diagram showing an example of clutch on / off control in the control of the vehicle air conditioner shown in FIG. 9;

FIG. 11 is an overall configuration diagram of another conventional vehicle air conditioner.

12 is a control block diagram of the vehicle air conditioner shown in FIG.

FIG. 13 is a characteristic diagram showing a control state of a conventional compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle air conditioner 2 Ventilation duct 3 Inside / outside air switching damper 4 Outside air introduction port 5 Inside air introduction port 6 Blower 7 Evaporator as indoor heat exchanger 8 Hot water heater as heater 9 Air mix damper actuator 10 Air mix damper 17 Refrigerant Circuit 18 Variable capacity compressor 19 Condenser 20 Liquid receiver 21 Expansion valve 22 Discharge pressure sensor 23 Discharge gas temperature sensor 24 Body temperature sensor 25 Evaporator sensor 26 Main controller 27 In-vehicle temperature setting device 28 Blower voltage controller 29 Vehicle interior temperature sensor 30 Solar radiation sensor 31 Outdoor temperature sensor 32 Engine ECU 41 Vehicle air conditioner 42 Condenser as indoor heat exchanger 43 Capacitor sensor 44 Evaporator as outdoor heat exchanger

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masato Tsuboi, 20 Kotobukicho, Isesaki-shi, Gunma Sanden Co., Ltd. (72) Inventor Kei Sugawara 20 Kotobukicho, Isesaki-shi, Gunma Sanden Co. ) 3L011 AC01

Claims (11)

[Claims] 1. A refrigerant circuit comprising a variable displacement compressor capable of arbitrarily varying a discharge capacity in response to a displacement control signal, an indoor heat exchanger provided in a ventilation duct, and heat of the indoor heat exchanger. Capacity target value setting means for setting a target value of the temperature representing the exchange capacity, refrigerant circuit operating state detecting means for detecting the operating state of the refrigerant circuit, and information from the temperature detecting means and the refrigerant circuit operating state detecting means An air conditioner for a vehicle, comprising: a control unit that controls a compressor capacity and controls a temperature representing the heat exchange capacity to a target temperature, wherein the control unit controls the refrigerant capacity to limit excessive control of the compressor capacity. Corresponding to the first set value set for the operation state amount of the circuit and the second set value higher than the first set value, the compressor capacity is set to the first or second set value range. The control capacity value when the An air conditioner for a vehicle, wherein two-position control is performed between a predetermined small control capacity value smaller than a control capacity value. 2. The vehicle air conditioner according to claim 1, wherein the indoor heat exchanger is a refrigerant evaporator. 3. The vehicle air conditioner according to claim 1, wherein the indoor heat exchanger is a refrigerant condenser. 4. The air conditioner for a vehicle according to claim 1, wherein a difference between the first set value and the second set value is a predetermined constant value. 5. The small control capacity value of the compressor capacity is set to a minimum capacity value of the variable capacity compressor.
5. The vehicle air conditioner according to any one of claims 4 to 4. 6. The method according to claim 2, wherein a difference between the first set value and the second set value is set for at least one of a compressor discharge pressure, a compressor discharge temperature, and a compressor body temperature.
The vehicle air conditioner according to any one of claims 4 and 5. 7. The difference between the first set value and the second set value is 0.2 MPa or less for compressor discharge pressure, 5 ° C. or less for compressor discharge temperature, and 5 ° C. for compressor body temperature. The vehicle air conditioner according to claim 6, wherein the temperature is set to not more than ° C. 8. The difference between the first set value and the second set value is set for at least one of a compressor suction pressure, a compressor discharge pressure, a compressor discharge temperature, and a compressor body temperature. An air conditioner for a vehicle according to any one of claims 3 to 5. 9. The difference between the first set value and the second set value is 0.04 MPa or less for the compressor suction pressure, 0.2 MPa or less for the compressor discharge pressure, and 5 ° C or less, the compressor body temperature is 5
The vehicle air conditioner according to claim 8, wherein the temperature is set to not more than ° C. 10. The vehicle air conditioner according to claim 1, wherein said refrigerant circuit operating state detecting means includes a pressure sensor or a temperature sensor capable of continuously detecting pressure or temperature. 11. The air conditioner for a vehicle according to claim 1, wherein said refrigerant circuit operating state detecting means includes a pressure switch or a temperature switch.