JP2003054249A - Vehicular air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular air conditioner capable of displaying its operational ability until its temperature reaches a limit temperature in the vicinity of a heat resistant temperature, by making it operable at a temperature not more than the heat resistant temperature even if a vehicle speed suddenly changes, and by applying inexpensive components having low heat resistant temperatures. SOLUTION: This vehicular air conditioner is provided with a temperature detecting means (temperature sensor 2) to detect the temperature of a coolant on the outlet side of a compressor 1 or the temperature of the winding of a motor to drive the compressor 1, a means (control device 15) for operating a rate of temperature change of a detected temperature by the temperature detecting means, and a control means 15 to adjust the temperature of the coolant discharged from the compressor 1 by compensating the opening of a pressure reducing valve 7, the operation of the compressor 1, or a quantity of heat exchanged in an internal heat exchanger 16, in accordance with the detected temperature by the temperature detecting means and the rate of temperature change by the means for operating the rate of temperature change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner.

[0002]

_2. Description of the Related Art Conventionally, an air conditioner for a vehicle equipped with a refrigeration cycle using CO ₂ as a refrigerant can be operated with the highest energy efficiency (COP) based on the refrigerant temperature at the outlet side of a heat exchanger outside the vehicle. (Japanese Patent Laid-Open No. 7-294033). Further, there is also a vehicle air conditioner to which an internal heat exchanger is applied in order to increase the enthalpy difference between the inlet side and the outlet side in the heat exchanger inside the vehicle.

[0003]

However, in the above-mentioned vehicle air-conditioning system, the function of the heat exchanger outside the vehicle is sharply increased due to a rapid increase in the rotational speed of the compressor due to a change in the rotational speed of the engine and a decrease in the traveling speed. There is a problem that the temperature of the refrigerant discharged from the compressor sharply rises due to such a decrease in temperature and an operation of increasing the air flow rate of the blower that blows air to the heat exchanger inside the vehicle.

On the other hand, a method of controlling the temperature of the refrigerant discharged from the compressor can be considered. However, when the traveling speed of the vehicle changes abruptly, its response is delayed. Therefore, in consideration of the time difference, it is necessary to use parts having a high heat resistant temperature in the vehicle air conditioner. In this case, the cost of the entire apparatus becomes high, and it must be set to operate at a low capacity so as not to exceed the limit of heat resistant temperature.

Therefore, according to the present invention, even if a sudden change in the vehicle speed occurs, it is possible to operate at a temperature lower than the heat resistant temperature of the component, so that an inexpensive component having a low heat resistant temperature can be applied, It is an object of the present invention to provide a vehicle air conditioner capable of exhibiting driving ability up to the limit temperature of.

[0006]

In order to solve the above-mentioned problems, the vehicular air-conditioning system of the present invention uses a pressure reducing valve to radiate the refrigerant composed of a supercritical fluid discharged from the compressor by the heat exchanger outside the vehicle. In a vehicle air conditioner equipped with a refrigeration cycle in which the pressure is reduced and vaporized by a heat exchanger inside the vehicle, and then returned to the compressor and circulated, the refrigerant temperature at the outlet side of the compressor or the motor for driving the compressor. Temperature detecting means for detecting the temperature of the winding wire, temperature change rate calculating means for calculating the change rate of the temperature detected by the temperature detecting means, temperature detected by the temperature detecting means and temperature change rate by the temperature change rate calculating means. And a control means for adjusting the opening of the pressure reducing valve or the operation of the compressor to adjust the temperature of the refrigerant discharged from the compressor. It is.

Alternatively, the refrigerant composed of a supercritical fluid discharged from the compressor is radiated by the heat exchanger outside the vehicle, decompressed by the pressure reducing valve, vaporized by the heat exchanger inside the vehicle, and then returned to the compressor for circulation. In a vehicle air conditioner including a refrigerating cycle, an internal heat exchanger for exchanging heat between a refrigerant between the vehicle exterior heat exchanger and a pressure reducing valve and a refrigerant between the vehicle interior heat exchanger and a compressor. By adjusting the amount of refrigerant between the vehicle exterior heat exchanger and the pressure reducing valve or the amount of refrigerant between the vehicle interior heat exchanger and the compressor, which is supplied into the internal heat exchanger. Heat exchange adjusting means for adjusting the amount of heat exchange by the heat exchanger, temperature detecting means for detecting the refrigerant temperature at the outlet side of the compressor, or temperature of the winding of the motor for driving the compressor, and the temperature detecting means. Temperature change rate calculation means for calculating the change rate of the detected temperature, and the amount of heat exchange in the internal heat exchanger is corrected according to the temperature detected by the temperature detection means and the temperature change rate by the temperature change rate calculation means. A control means for adjusting the temperature of the refrigerant discharged from the compressor is provided.

Here, the temperature of the refrigerant discharged from the compressor is lowered by increasing the opening of the pressure reducing valve and is increased by decreasing the opening. Further, it is lowered by operating the compressor at a low rotation speed, and is increased by operating at a high rotation speed. Further, it is lowered by decreasing the heat exchange amount by the internal heat exchanger, and is increased by increasing the heat exchange amount. Therefore, the temperature of the refrigerant discharged from the compressor can be adjusted by correcting the opening of the pressure reducing valve, the operation of the compressor, and the amount of heat exchange by the internal heat exchanger.

Particularly, according to the vehicle air conditioner, the refrigerant temperature is adjusted based on the rate of change of the refrigerant temperature discharged from the compressor. Therefore, when the temperature of the refrigerant discharged from the compressor starts to rise, it can be predicted whether or not the temperature will rise to a temperature exceeding the heat resistant temperature of each component depending on the rising rate. If the temperature change rate is predicted (determined) to exceed the heat resistant temperature of the component, the temperature of the refrigerant is lowered responsively in the initial stage where the heat resistant temperature has not yet been exceeded so that the heat resistant temperature is not exceeded. Can be adjusted. Therefore, it is possible to apply an inexpensive component having a low heat resistant temperature.

In the vehicle air conditioner, when the temperature detected by the temperature detecting means is higher than the first set value and the temperature change rate is higher than the second set value, the temperature of the refrigerant discharged from the compressor is lowered. It is preferable to adjust. By doing so, it is possible to more reliably control the temperature of each component below the heat-resistant temperature.

In this case, it is preferable to set the second set value based on the temperature detected by the temperature detecting means. In this way, fine adjustment can be performed in a wide range based on the detected refrigerant temperature, so that it is possible to more reliably control the temperature below the heat resistant temperature of each component.

Further, the refrigerant is preferably CO ₂ . Here, since CO ₂ has a small global warming potential, global warming can be prevented.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a refrigeration cycle of a vehicle air conditioner according to a first embodiment of the present invention. In this refrigeration cycle, the refrigerant discharged from the compressor (here, CO ₂ is used) is passed from the oil separator 3, the vehicle exterior heat exchanger 5, the pressure reducing valve 7, and the vehicle interior heat exchanger 8 through the accumulator 14. And returns to the compressor 1 for circulation. The control device 15 drives and controls the compressor 1, the pressure reducing valve 7, and the vehicle exterior blower 6 described later.

The compressor 1 can be driven by the power of an engine (not shown). A temperature sensor 2 which is a temperature detecting means is provided in the outlet side pipe of the compressor 1.

The oil separator 3 separates the oil contained in the refrigerant discharged from the compressor 1 and returns it to the compressor 1 via the oil return pipe 4.

The exterior heat exchanger 5 is arranged in the front portion of the vehicle and has a conventionally well-known structure suitable for radiating the heat of the refrigerant. The exterior heat exchanger 5 includes an exterior blower 6. The blower 6 for outside the vehicle is configured such that the amount of air blown is freely changeable, and the amount of heat released from the refrigerant in the vehicle outer side heat exchanger 5 (heat exchange efficiency) can be adjusted by changing the amount of air blown.

The pressure reducing valve 7 adjusts the pressure of the refrigerant on the upstream side by changing the opening degree and reduces the pressure of the passing refrigerant. It is possible to adjust the refrigerant temperature by adjusting the pressure of the refrigerant on the upstream side with the pressure reducing valve 7. Specifically, increasing the opening of the pressure reducing valve lowers the temperature of the upstream refrigerant, and decreasing the opening increases the temperature of the upstream refrigerant.

The heat exchanger 8 on the inside of the vehicle is arranged in the air conditioning unit 9 at the front of the vehicle and has a conventionally well-known structure for cooling and dehumidifying the air passing through the air conditioning unit 9. A blower 11 that is rotated by the drive of a blower motor 10 is disposed on the upstream side of the vehicle interior heat exchanger 8 in the air conditioning unit 9 and blows inside air or outside air into the vehicle at a predetermined air volume. In addition, the heat exchanger 8 inside the vehicle of the air conditioning unit 9
An air mix door 12 is rotatably provided on the downstream side of the, to divert the cool air and direct one of the air to the heater core 13. The air mix door 12 has an amount of air heated by the heater core 13 depending on its rotational position (opening degree),
That is, the ratio of the mixed cold air and warm air is changed and the air is blown into the vehicle at a desired temperature.

The accumulator 14 separates the refrigerant into gas and liquid, and circulates and supplies only the gas phase to the compressor 1.

The control device 15 serves as a temperature change rate calculating means for calculating the change rate of the temperature detected by the temperature sensor 2. Then, based on a preset program, the drive rotation speed of the compressor 1, the opening degree of the pressure reducing valve 7, the amount of air blown by the exterior blower 6, or the air mix door 1
The rotation position of 2 is adjusted.

Further, in this embodiment, the temperature sensor 2
The opening degree of the pressure reducing valve 7 is corrected according to the rate of change of the refrigerant temperature detected through the calculated and the calculated temperature of the refrigerant, and the temperature of the upstream refrigerant discharged from the compressor 1 is adjusted. Specifically, this adjustment control of the refrigerant temperature is
When the temperature detected by the temperature sensor 2 is higher than the first set value k1 and the temperature change rate is higher than the second set value k2, the temperature of the refrigerant discharged from the compressor 1 is adjusted to be low.

Next, the operation of the vehicle air conditioner having the above-mentioned structure will be specifically described. First, the refrigerant composed of a supercritical fluid discharged at a high temperature and high pressure by driving the compressor passes through the oil separator 3, is radiated by the exterior heat exchanger 5 and liquefied, and is decompressed by the pressure reducing valve 7. When passing through the heat exchanger 8 inside the vehicle, it is vaporized, separated into gas and liquid by the accumulator 14, and only the gas phase returns to the compressor 1 and circulates.

In the oil separator 3, the oil leaked from the compressor 1 together with the refrigerant is separated,
Only the oil is returned to the compressor 1 via the oil return pipe 4.

In this vehicle air conditioner, the refrigerant is HFC-
Even when using CO ₂ having a theoretically low energy efficiency (COP) as compared with other refrigerants such as 134a, a desired effect can be exhibited. Since CO ₂ has a small global warming potential, it can prevent global warming.

Next, the pressure reducing valve 7 is controlled by the controller 15.
Control for correcting the opening degree of and adjusting the temperature of the refrigerant discharged from the compressor 1 will be described. In this adjustment control, as shown in FIG. 2, first, in step S1, the current opening of the pressure reducing valve 7 is read, and then in step S2, the temperature Td1 of the refrigerant discharged from the compressor 1 via the temperature sensor 2 is read. Is detected and the process proceeds to step S3.

In step S3, the detected refrigerant temperature Td
Set value k0 (110), where 1 is the heat resistant temperature of each component
℃) is detected. And the refrigerant temperature Td
If 1 is less than or equal to the set value k0, the process proceeds to step S4, and if the refrigerant temperature Td1 is higher than the set value k0, steps S4 to S7 are skipped and step S8 is performed.
Proceed to.

In step S4, it is detected whether the detected refrigerant temperature Td1 is higher than a preset first set value k1. Then, when the refrigerant temperature Td1 is equal to or lower than the first set value k1, the process returns to step S1 and the refrigerant temperature Td1
Is higher than the first set value k1, the process proceeds to step S5.

The first set value k1 is 1 in this embodiment.
It is set to 00 ° C. That is, the heat resistant temperature of the component is 110
Compressor 1 when temperature exceeds 100 ° C
By adjusting the temperature of the refrigerant discharged from the component, the operating ability is exhibited up to the limit temperature around the heat resistant temperature of each component.

When the detected refrigerant temperature Td1 is higher than the first set value k1, in step S5, the refrigerant temperature Td2 discharged from the compressor 1 via the temperature sensor 2 again.
Is detected, the change rate ΔTd of the detected temperature is calculated in step S6, and the process proceeds to step S7. This detected temperature change rate ΔT
d is the difference between the detected refrigerant temperatures Td1 and Td2 (Td2-
Td1) is the time difference (t2-t1) at which these are detected
It is calculated by dividing by.

When the detected temperature change rate ΔTd is calculated,
In step S7, it is detected whether the calculated change rate ΔTd is larger than the second set value k2. And the rate of change ΔT
If d is greater than the second set value k2, the process proceeds to step S8, and if the change rate ΔTd is less than or equal to the second set value k2, the process returns to step S1.

The second set value k2 is the first set value k.
1 is set based on the graph shown in FIG.
That is, the second set value k2 is substantially the limit of the rate of change of the detected refrigerant temperature, and if it exceeds that value, the refrigerant temperature may rise to a temperature exceeding the heat resistant temperature of each component. If it is below, there is no fear of exceeding the heat resistant temperature. In the present embodiment, the set value k1 is 10
Since the temperature is 0 ° C., the set value k2 is 110 ° C.

The calculated change rate ΔTd is the second set value k.
If it is larger than 2, in step S8, the current pressure reducing valve 7
Step S1 is performed by correcting the opening degree of 10 pulses.
Return to. Here, 10 pulses is about 5% when converted into the opening degree of the pressure reducing valve 7.

As described above, in the present embodiment, the temperature of the refrigerant discharged from the compressor 1 is corrected by correcting the opening of the pressure reducing valve 7 on the basis of the refrigerant temperature Td1 discharged from the compressor 1 and the rate of change ΔTd of the temperature. Adjust.

In particular, in the present embodiment, the refrigerant temperature is adjusted based on the detected rate of change ΔTd of the refrigerant temperature. Therefore, at the initial stage when the temperature of the refrigerant discharged from the compressor begins to rise, each component is adjusted by the rate of increase. It is possible to predict whether or not the temperature will exceed the heat resistant temperature of the component. When it is predicted (determined) that the rate of temperature change exceeds the heat resistant temperature of the component, the temperature of the refrigerant is lowered in the initial stage where the heat resistant temperature has not yet been exceeded, and adjustment is made so that the heat resistant temperature is not exceeded. , Very responsive. Therefore, even if the temperature of the refrigerant discharged from the compressor 1 suddenly rises due to the abrupt change of the vehicle speed, the adjustment control for lowering the temperature may not be delayed and the heat resistant temperature of each component may be exceeded. It can be surely prevented.

As a result, according to the configuration of this embodiment, it is possible to apply inexpensive components having a low heat resistant temperature. Further, by setting the first set value k1, the driving ability can be exhibited up to the limit temperature near the heat resistant temperature of each component, so that the high driving ability can be secured.

FIG. 4 shows a vehicle air conditioner of the second embodiment. In the second embodiment, an internal heat exchanger 16 for exchanging heat between the refrigerant between the vehicle outside heat exchanger 5 and the pressure reducing valve 7 and between the vehicle inside heat exchanger 8 and the compressor 1.
And a heat exchange adjusting valve 17 for adjusting the amount of heat exchange by the internal heat exchanger 16.

The internal heat exchanger 16 exchanges heat between the high-pressure refrigerant flowing out of the vehicle exterior heat exchanger 5 and the low-pressure refrigerant flowing out of the vehicle interior heat exchanger 8 so that the internal heat exchanger 8 This is to increase the enthalpy difference between the entrance side and the exit side.

The heat exchange adjusting valve 17 is connected in parallel with the internal heat exchanger 16 between the vehicle interior heat exchanger 8 and the compressor 1, and controls the amount of refrigerant flowing into the internal heat exchanger 16. By adjusting, the amount of heat exchange in the internal heat exchanger 16 is adjusted. The heat exchange adjustment valve 17 may be provided between the vehicle exterior heat exchanger 5 and the pressure reducing valve 7.

The controller 15 of the second embodiment adjusts the opening of the heat exchange adjusting valve 17 instead of the pressure reducing valve 7 according to the temperature detected by the temperature sensor 2 and the calculated rate of change of temperature. Therefore, the temperature of the refrigerant on the upstream side discharged from the compressor 1 is adjusted by correcting the amount of heat exchange in the internal heat exchanger 16.
This is different from the embodiment.

In the control control of the temperature of the refrigerant discharged from the compressor 1 by the control device 15 of the second embodiment, in the control flow shown in FIG. 2, the detected temperature of the refrigerant discharged from the compressor 1 in step S4 is the first temperature. Set value k1
The temperature change rate is larger than the second set value k in step S7.
If it is larger than 2, the opening degree of the heat exchange regulating valve 17 is reduced in step S8.

Here, as shown in FIG. 5, the relationship between the opening degree of the heat exchange adjusting valve 17 and the refrigerant temperature discharged from the compressor 1 is that the refrigerant temperature increases as the opening degree increases, and The smaller the temperature, the lower the coolant temperature.
That is, by increasing the opening degree of the heat exchange adjusting valve 17, the amount of refrigerant passing through the inside of the internal heat exchanger 16 decreases. As a result, the heat exchange efficiency between the high-pressure refrigerant and the low-pressure refrigerant decreases, and the refrigerant temperature discharged from the compressor 1 decreases. On the contrary, by reducing the opening degree of the heat exchange adjusting valve 17, the amount of refrigerant passing through the internal heat exchanger 16 increases. As a result, the heat exchange efficiency between the high pressure refrigerant and the low pressure refrigerant is improved, and the temperature of the refrigerant discharged from the compressor 1 is increased.

Therefore, in the second embodiment, when the detected temperature of the refrigerant discharged from the compressor 1 is larger than the first set value k1 and the temperature change rate is larger than the second set value k2, the heat exchange adjusting valve 17 is operated. By increasing the opening degree, the temperature at the outlet side of the compressor 1 can be lowered with good responsiveness, as in the first embodiment.

The vehicle air conditioner of the present invention is not limited to the configuration of the above embodiment. For example, the temperature of the refrigerant discharged from the compressor 1 is adjusted by correcting the opening degree of the pressure reducing valve 7 in the first embodiment and the amount of heat exchange by the internal heat exchanger 16 in the second embodiment. The discharged refrigerant temperature may be adjusted by controlling the rotation speed. That is, when the temperature of the refrigerant discharged from the compressor 1 is higher than the first set value k1 and the temperature change rate is higher than the second set value k2, the compressor 1
May be corrected so that the number of rotations of the refrigerant is reduced, and the temperature of the discharged refrigerant may be adjusted to be lowered. By correcting the rotation speed of the compressor 1 in this way, the responsiveness can be further improved.

In each of the above embodiments, the compressor 1 driven by the power of the engine is used, but the compressor 1 driven by a motor may be applied. In this case, the temperature of the winding of the motor may be detected by the temperature sensor 2, and the temperature of the refrigerant discharged from the compressor 1 may be adjusted based on the detected temperature and the temperature change rate. Specifically, the motor that drives the compressor 1 discharges the refrigerant at high pressure and high temperature as the number of rotations increases, and the temperature of the winding also rises. Therefore, by detecting the temperature of the winding of the motor, the same control as described above is possible, and the same action and effect can be obtained.

Further, in each of the above embodiments, the second set value k2 is a preset invariable value, but it may be changed based on the temperature detected by the temperature sensor 2. That is, in the control flow shown in FIG. 2, the value of the first set value k1 to be compared in step S4 is set to 80 ° C. to set a wide range. Then, the set value k2 is set based on the temperature Td1 detected in step S2. Specifically, according to the graph shown in FIG. 3, when the detected refrigerant temperature Td1 is 80 ° C., the second set value k2 is 120 ° C., and when it is 90 ° C., the second set value k2 is second.
When the set value k2 is 115 ° C and 100 ° C, the second set value k2 is set to 110 ° C. Then, in step S7,
By comparing the set value k2 and the temperature change rate ΔTd,
The opening of the pressure reducing valve 7, the operation of the compressor 1, or the amount of heat exchange by the internal heat exchanger 16 is corrected to
Adjust the temperature of the refrigerant discharged from.

As described above, by setting the second set value k2 based on the temperature detected by the temperature sensor 2, fine adjustment can be performed in a wide range, so that the heat resistance of each component can be more reliably achieved. Control below temperature is possible.

[0047]

As is apparent from the above description, the vehicle air conditioner according to the present invention adjusts the refrigerant temperature based on the rate of change of the refrigerant temperature discharged from the compressor. When the temperature of the refrigerant starts to rise, it can be predicted by the rate of rise that the temperature will rise to a temperature exceeding the heat resistant temperature of each component. If the temperature change rate is predicted (determined) to exceed the heat resistant temperature of the component, the temperature of the refrigerant is lowered responsively in the initial stage where the heat resistant temperature has not yet been exceeded so that the heat resistant temperature is not exceeded. Can be adjusted. Therefore, it is possible to apply an inexpensive component having a low heat resistant temperature.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a vehicle air conditioner according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing control for adjusting the temperature of discharged refrigerant by the control device of the first embodiment.

FIG. 3 is a graph showing the relationship between the second set value and the temperature of the refrigerant discharged from the compressor.

FIG. 4 is a schematic diagram of a vehicle air conditioner according to a second embodiment.

5 is a graph showing the relationship between the opening of the heat exchange control valve of FIG. 4 and the temperature of the refrigerant discharged from the compressor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Temperature sensor, 3 ... Oil separator, 5 ... Exterior heat exchanger, 6 ... Exterior blower, 7 ... Pressure reducing valve, 8 ... Interior heat exchanger, 9 ... Air conditioning unit, 14 ...
Accumulator, 15 ... Control device, 16 ... Internal heat exchanger, 17 ... Heat exchange regulating valve.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F25B 1/00 304 F25B 1/00 304P 395 395Z (72) Inventor Shinji Watanabe Yoshikawa Industrial Park, Higashihiroshima City, Hiroshima Prefecture 3-11 Stock Company Nippon Climate Systems Co., Ltd.

Claims (5)

[Claims] 1. A refrigerant composed of a supercritical fluid discharged from a compressor is radiated by a heat exchanger outside the vehicle, decompressed by a pressure reducing valve, vaporized by a heat exchanger inside the vehicle, and then returned to the compressor for circulation. In a vehicle air conditioner having a refrigerating cycle, a temperature detecting means for detecting a refrigerant temperature on the outlet side of the compressor or a winding temperature of a motor for driving the compressor, and a temperature detecting means for detecting the temperature detected by the temperature detecting means. A temperature change rate calculating means for calculating a change rate; and an opening of the pressure reducing valve or a compressor operation is corrected according to the temperature detected by the temperature detecting means and the temperature change rate by the temperature change rate calculating means. A vehicle air conditioner comprising: a control unit that adjusts the temperature of the refrigerant discharged from the compressor. 2. A refrigerant composed of a supercritical fluid discharged from a compressor is radiated by a heat exchanger outside the vehicle, decompressed by a pressure reducing valve, vaporized by a heat exchanger inside the vehicle, and then returned to the compressor for circulation. In a vehicle air conditioner having a refrigerating cycle, an internal heat exchanger for exchanging heat between a refrigerant between the outside heat exchanger and a pressure reducing valve and a refrigerant between the inside heat exchanger and a compressor. And adjusting the amount of refrigerant between the vehicle exterior heat exchanger and the pressure reducing valve or the amount of refrigerant between the vehicle interior heat exchanger and the compressor to be supplied into the internal heat exchanger. Heat exchange adjusting means for adjusting the amount of heat exchange by the heat exchanger; temperature detecting means for detecting the refrigerant temperature at the outlet side of the compressor or the temperature of the winding of the motor for driving the compressor; and the temperature detecting means. By Temperature change rate calculating means for calculating the change rate of the detected temperature; and the heat exchange amount in the internal heat exchanger is corrected according to the temperature detected by the temperature detecting means and the temperature change rate by the temperature change rate calculating means. A vehicle air conditioner comprising: a control unit that adjusts the temperature of the refrigerant discharged from the compressor. 3. The temperature detected by the temperature detecting means is first
The refrigerant temperature discharged from the compressor is adjusted to decrease when the temperature change rate is larger than a set value and the temperature change rate is larger than a second set value. Vehicle air conditioner. 4. The vehicle air conditioner according to claim 3, wherein the second set value is set based on the temperature detected by the temperature detecting means. 5. The vehicle air conditioner according to any one of claims 1 to 4, wherein the refrigerant is CO ₂ .