JP2005238951A - Control device for air conditioner for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an air conditioner for a vehicle that can control the generation of liquid compression sound within a compressor at the time of use of a vehicle by the liquid-compression actuation of the compressor at the time when the vehicle is not used, thus can eliminate transfer of the liquid compression sound to a passenger. <P>SOLUTION: The control device is provided with a starter 2, the compressor 31, and a control means 4. The starter starts an engine 1 mounted on the vehicle, and the compressor constitutes a refrigeration cycle of the air conditioner and is driven by the engine 1. Then the control means actuates the starter 2 and the compressor 31. The control means 4 starts the starter 2 when it estimates that a refrigerant for the air conditioner is liquefied within the compressor 31 at the time when the vehicle is not used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicular air conditioner control apparatus that can reduce the liquid compression sound of an air conditioner compressor that a user feels while riding, thereby reducing discomfort to the user.

  It is known that the liquefaction phenomenon in which the air conditioner refrigerant, which should be a gas, is in a liquid state inside the compressor used in the vehicle air conditioner is caused by the fact that the heat capacity of the compressor is larger than that of other devices. ing. That is, the vehicle itself on which the air conditioner is mounted is usually in a state of being almost exposed to the outside air. In addition, the temperature rises due to solar radiation in the vehicle, and the temperature of the condenser and the evaporator constituting the refrigeration cycle, including the compressor, changes under the influence of the outside air temperature and the vehicle interior temperature.

  For example, FIG. 7 shows a temperature change of each device with respect to a change in the outside air temperature for one day. While the condenser changes substantially following the change in the outside air temperature, the temperature of the evaporator, which is substantially the room temperature, is also affected by solar radiation into the vehicle interior, especially during the daytime. Nearby also gets higher. However, since the heat capacity of the compressor is larger than that of the above two devices, it takes time to change the temperature, and it is difficult to follow the outside air temperature. It will be.

  Therefore, when the temperature of the evaporator and its surrounding piping rises, the internal pressure on the evaporator rises, generating a force that pushes up the liquefied refrigerant on the condenser side, and if the refrigerant exceeds the set height at the condenser inlet, so-called oil return Therefore, a phenomenon occurs in which the liquid refrigerant flows backward in the compressor disposed at the lowermost end of the refrigerant circulation system. In this way, liquefaction (liquid condensation) often occurs, for example, in the time zone indicated by the solid line arrow in FIG.

  In this way, liquefaction in the compressor occurs throughout the year because it is largely caused by the difference in the outside air temperature between day and night and the size of the heat capacity of the compressor, but it depends on the frequency of occurrence and the state of liquefaction individually. There is a difference in degree.

Therefore, conventionally, in order to vaporize the air-conditioning refrigerant in the compressor using an electric heater or the like (see Patent Document 1), or to reduce the liquid compression sound in the compressor or make it inconspicuous, It is known to operate a compressor (see Patent Document 2).
JP-A-9-126561 JP 2002-120551 A

  However, in the technique of Patent Document 1, if the liquefied refrigerant is not completely vaporized, a liquid compression sound may be generated from the compressor when the air conditioner is started to operate. In addition, as in Patent Document 2, in consideration of the timing of operating the compressor, for example, even when the liquid compression sound is masked by superimposing the engine start sound, there is an occupant in the vehicle interior, so It is difficult to make it unheard.

  The present invention has been made in view of the above points, and by causing the compressor to perform a liquid compression operation when the vehicle is not used, it is possible to suppress the generation of the liquid compression sound in the compressor when the vehicle is used, and the liquid compression sound is occupant. It is an object of the present invention to provide a vehicle air conditioner control device capable of eliminating transmission to the vehicle.

  In order to achieve the above object, the technical means according to claims 1 to 7 are employed.

According to the first aspect of the present invention, there is provided a starter for starting an engine mounted on a vehicle, a refrigeration cycle of an air conditioner, a compressor driven by the engine, and a control means for operating the starter and the compressor. ,
This control means operates the starter when it is estimated that the air-conditioning refrigerant is liquefied in the compressor when the vehicle is not used.

  As a result, when it is estimated that the air-conditioning refrigerant is liquefied in the compressor when the vehicle is not in use, the compressor is liquid-compressed to suppress the occurrence of liquid compression noise in the compressor when the vehicle is used. It is possible to eliminate the transmission of the liquid compression sound to the occupant.

  According to the second aspect of the present invention, the control means has soak timer means for starting the control means at predetermined time intervals when the vehicle is not in use, and for the air conditioner at predetermined time intervals activated by the soak timer means. Estimating whether the refrigerant is liquefied, and if the liquefaction is estimated, by operating the starter for a predetermined period, the control means can be activated periodically when the vehicle is not in use to estimate the occurrence of the refrigerant liquefaction phenomenon. Thus, it is possible to achieve both saving of power consumption by the control means and regular monitoring of refrigerant liquefaction.

According to invention of Claim 3, the outside temperature sensor which detects outside temperature, and the inside temperature sensor which detects the room temperature of a vehicle are provided,
The control means takes in the outside air temperature value from the outside air temperature sensor every predetermined time, and when this outside air temperature value is lower than the stored minimum outside air temperature value, the outside air temperature value is updated and stored as the minimum outside air temperature value, When the difference between the lowest outside air temperature value and the room temperature value taken from the inside air temperature sensor is equal to or greater than a predetermined value, it is estimated that the air-conditioning refrigerant is liquefied in the compressor.

  Thus, without directly measuring the temperature state of the evaporator and the compressor constituting the refrigeration cycle, the evaporator is used by using the vehicle room temperature substantially equal to the evaporator temperature when the vehicle is not used and the outside air temperature substantially equal to the compressor temperature. The temperature of the compressor can be estimated, and the liquefaction of the refrigerant inside the compressor can be estimated without adding a special temperature sensor.

  According to the fourth aspect of the present invention, when the starter is operated when the vehicle is not used, the control means stops the fuel supply to the engine so that the engine can be started even if the starter is operated. Therefore, it is possible to ensure the safety of the vehicle when the user is absent.

  According to the fifth aspect of the present invention, when the control means operates the starter when the vehicle is not in use, when the neutral switch of the transmission for transmitting the engine driving force mounted on the vehicle is in the neutral state, When the starter is operated, the driving force is not transmitted to the wheel side even when the starter is operated, so that the vehicle does not move, and the safety of the vehicle when the user is absent can be ensured.

According to invention of Claim 6, the water temperature sensor which detects engine cooling water temperature, and the internal temperature sensor which detects the room temperature of a vehicle are provided,
The control means takes in the water temperature value from the water temperature sensor every predetermined time, and when this water temperature value is lower than the stored minimum water temperature value, the water temperature value is updated and stored as the minimum water temperature value. When the difference from the room temperature value taken in from the temperature sensor is a predetermined value or more, it is estimated that the air-conditioning refrigerant is liquefied in the compressor.

  As a result, the liquefaction of the refrigerant can be estimated using the water temperature sensor in the same manner as the outside air temperature sensor, and the outside air temperature sensor can be substituted or supplemented.

According to invention of Claim 7, it comprises the refrigerating cycle of the air-conditioner mounted in a vehicle, it is equipped with the electric compressor driven by an electric motor, and the control means which operates this electric compressor,
The control means operates the electric compressor when it is estimated that the refrigerant for the air conditioner is liquefied in the electric compressor when the vehicle is not used.

  Thereby, the same effect as that of claim 1 can be expected.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing an overall configuration of a vehicle air conditioner control device, in which an engine 1 that is an internal combustion engine mounted on a vehicle, a starter 2 that starts the engine 1, and an air conditioner 3 that constitutes a refrigeration cycle of an air conditioner. , An engine ECU 4 that controls on / off (connection / disconnection) of the compressor 31 of the engine 1 and the air conditioner 3, an air conditioner ECU 5 that generates necessary control signals for the air conditioner 3 and the engine ECU 4, an in-vehicle battery 6, a starter relay 7, and a power source Relay 8, neutral switch 10 that detects the neutral shift position of the transmission that transmits the driving force of the engine 1 to the wheels, an engine speed sensor 11 that detects the speed of the engine 1, and the temperature of the cooling water of the engine 1 An engine water temperature sensor 12 that performs ignition, an ignition device that adjusts the ignition timing of the engine 1 and the amount of fuel supplied, and fuel Mainly composed of the driving device 13, and the air conditioning control various sensors 51 to 54 etc., such as injectors.

  The engine ECU 4 is supplied with power from the storage device 41a capable of storing data even when the ignition switch 9 is OFF, the microcomputer 41 having a CPU, ROM, RAM, and the like, the power circuit 42, and the battery 6 at all times. And a soak timer 43 that operates when the vehicle is not in use, such as when it is left (soaked), and an activation circuit 44 that drives the power relay 8. Here, the storage device 41a includes a power-backed RAM provided inside or outside the microcomputer 41, and a nonvolatile memory such as an EEPROM or a flash ROM. The engine ECU 4 and the air conditioner ECU 5 can be integrated into one ECU.

  The soak timer 43 starts counting from the time when the ignition switch 9 is stopped when the engine 1 is stopped, continuously counts the time during the OFF period, and generates an operation instruction signal having a predetermined time width every time a certain period of time elapses. When the ignition switch 9 is turned on again, the timekeeping state is reset.

  The start circuit 44 generates an L level start signal and operates the power supply relay 8 when receiving either the operation instruction signal generated at regular intervals from the soak timer 43 or the ON signal of the ignition switch 9. Therefore, the power supply relay 8 is closed to enable power supply from the battery 6 to the engine ECU 4.

  The air conditioner ECU 5 includes an outside air temperature value (outside air temperature information) Ta from an outside air temperature sensor 51 disposed in the vicinity of the air intake port of the vehicle, a vehicle room temperature value (vehicle room temperature information) from an inside air temperature sensor 52 disposed in the vehicle interior. ) Tr, the amount of solar radiation from the solar radiation sensor 53 (sunlight amount information), and an air conditioning operation instruction signal from the air conditioning switch 54 instructing the operation of the air conditioning system are supplied. The air conditioning switch 54 includes all switches that make the compressor 31 operable, such as a fan switch for making the air conditioner compressor 31 operable.

  The air conditioner ECU 5 controls the air conditioner 3 based on signals from various sensors 51 to 54. The air conditioning control signal of the air conditioner ECU 5 is also output to the engine ECU 4. The engine ECU 4 outputs a clutch signal instructing connection or disconnection to the electromagnetic clutch 35 of the compressor 31 based on the air conditioning control signal from the air conditioner ECU 5 and other signals.

  Here, the air conditioner 3 is mainly composed of the following refrigeration cycle. That is, the compressor 31 is driven by the engine 1 via the electromagnetic clutch 35 and compresses a relatively low-temperature and low-pressure gaseous refrigerant into a high-temperature and high-pressure gaseous refrigerant, and the gaseous refrigerant is cooled by outside air to be liquid refrigerant. A condenser 32 that changes the temperature of the liquid refrigerant, an expansion valve 33 that rapidly expands the liquid refrigerant to output a low-temperature and low-pressure mist-like refrigerant by vaporization, and heat from the high-temperature indoor air that is in contact with the pipe surface by the mist-like refrigerant. The evaporator 34 is mainly composed of an evaporator 34 that cools the air in the passenger compartment and vaporizes the mist refrigerant and returns it to the compressor 31.

  A blower fan (not shown) is disposed facing the evaporator 34, and the air volume is controlled by the air conditioner ECU 5. The compressor 31 is driven from the engine 1 via the crank pulley 37 and the drive belt 36 when the clutch 35 is connected upon receiving a clutch signal instructing closing from the engine ECU 4.

  Next, the operation of the vehicle air conditioner control apparatus including both the ECUs 4 and 5 will be described with reference to the drawings.

  FIG. 2 shows a base routine of the engine ECU 4. When the power relay 8 is closed and power is supplied to the engine ECU 4, this routine is first performed.

  If it is determined in step 101 that the ignition switch 9 has been turned on, the process proceeds to steps 102 to 104 to perform initialization or initial setting processing. That is, the data of the execution history F indicating that the compressor 31 has been forcibly operated when the vehicle is not used, such as during previous parking or soak (leaving), is initialized (step 102). The execution history F data will be described later. Subsequently, the outside air temperature value Ta detected by the outside air temperature sensor 51 is read (step 103), and instead of the lowest outside air temperature value Tamin stored in the storage device 41a in the previous unused time, the latest air temperature value read this time is read. The outside air temperature value Ta is updated and stored in the storage device 41a (step 104).

  On the other hand, if it is determined in step 101 that the ignition switch 9 is in the OFF state or is not being turned ON but is still ON, the initialization or initial setting process is determined to be unnecessary and the process ends.

  By the routine described above, the engine ECU 4 initializes the data of the execution history F when the ignition switch 9 is turned on, and the storage area of the storage device 41a that stores the minimum outside air temperature value Tamin detected when the vehicle is not used. In addition, the latest outside air temperature value Ta is stored. As a result, the storage area can be shared for storing the minimum outside air temperature value Tamin and the latest outside air temperature value Ta, and the minimum outside air temperature value Tamin during this period can be detected every period when the vehicle is not used. ing.

  Next, a soak timer activation process of the engine ECU 4 that is a characteristic part of the present invention will be described with reference to FIGS.

  The feature of this process is that the temperature state of the air conditioner 3 is monitored when the vehicle is not used, such as when parked or left unattended, and a liquefaction phenomenon occurs in which the air conditioner refrigerant, which should be essentially gas, becomes a liquid state inside the compressor. When it is estimated that the refrigerant has been liquefied, the compressor 31 is operated to generate an abnormal liquid compression sound during a period when the user is not present, thereby making the user feel uncomfortable while driving the vehicle. It is to avoid giving.

  First, the procedure for estimating the liquefaction of the refrigerant inside the compressor will be described with reference to FIG. The liquefaction phenomenon of the refrigerant is caused by the temperature difference (Te> Tc) between the temperature Te on the evaporator 34 side and the temperature Tc of the compressor 31, and this temperature difference increases from early morning to daytime, and the liquefaction phenomenon is likely to occur at that time. It has been known. Although the temperature Tc of the compressor 31 in the early morning is approximate to the outside air temperature Ta, even if the outside air temperature Ta rises after the early morning, the heat capacity of the compressor 31 itself is large, so the change in the outside air temperature Ta cannot be followed. It can be estimated that it is substantially equal to the minimum outside air temperature Tamin. On the other hand, since the evaporator 34 is normally in contact with the air in the passenger compartment, it can be estimated that the evaporator 34 is substantially equal to the vehicle room temperature Tr.

  Therefore, when the temperature difference between the vehicle room temperature Tr and the minimum outside air temperature Tamin, that is, the refrigerant liquefaction determination value Tx is larger than the predetermined temperature difference To obtained in advance through experiments or the like, it can be estimated that a liquefaction phenomenon has occurred. By calculating and determining the difference, the liquefaction phenomenon occurring in the compressor 31 can be monitored. Times t1 to t4 in FIG. 5 are examples of monitoring timing.

  Hereinafter, the soak timer activation process will be described. When an operation instruction signal is generated from the soak timer 43, the power relay 8 is closed via the starting circuit 44, and power is supplied to the engine ECU 4. Therefore, the engine ECU 4 starts operating, and performs a soak timer activation process shown in FIGS. 3 and 4 after the base routine process shown in FIG.

  First, various information such as the outside air temperature Ta, the vehicle room temperature Tr, and the minimum outside air temperature Tamin is read from the various sensors 51 and 52 and the storage device 41a (step 201), and in step 202, the minimum outside air temperature stored as the outside air temperature Ta. Compare the size with Tamin. When the outside air temperature Ta is lower than the stored minimum outside air temperature Tamin, the routine proceeds to step 203, where the current outside air temperature Ta is updated so as to become the minimum outside air temperature Tamin, and stored in the storage device 41a. On the other hand, in step 202, when the outside air temperature Ta is higher than the stored minimum outside air temperature Tamin, step 203 is passed to proceed to step 204, and the minimum outside air temperature Tamin is not updated.

  Subsequently, a temperature difference between the vehicle room temperature Tr and the minimum outside air temperature Tamin, that is, a refrigerant liquefaction determination value Tx is calculated (step 204), and a magnitude comparison between the refrigerant liquefaction determination value Tx and a predetermined temperature difference To obtained in advance through experiments or the like is performed. (Step 205). When the refrigerant liquefaction determination value Tx is larger than the predetermined temperature difference To, it is estimated that a refrigerant liquefaction phenomenon has occurred inside the compressor 31. Therefore, in step 206, if there is no execution history F indicating that the compressor 31 has already been operated during the current unused period, the process proceeds to step 207 shown in FIG. Here, the value of the predetermined temperature difference To is a value corresponding to the amount of the liquefied refrigerant at which the liquid compression sound generated during the compression operation of the liquefied refrigerant accumulated in the compressor 31 becomes so large that it cannot be ignored.

  On the other hand, when the refrigerant liquefaction determination value Tx is smaller than the predetermined temperature difference To in step 205 or when there is an execution history F in which the compressor 31 has already been operated in the current unused period in step 206, the soak timer activation process is performed. finish. This is because when the former temperature difference is small, it is estimated that the refrigerant liquefaction phenomenon in the compressor 31 hardly occurs. In the latter case, the starter 2 is already driven to operate the compressor 31 during the unused period, and the liquid refrigerant is compressed, and the liquid refrigerant in the compressor 31 is reduced. This is to prevent the battery 6 from being discharged due to overdischarge of the battery 6 by limiting the number of times that the starter 2 is driven.

  Subsequently, in Steps 207 and 208, when the transmission is in the neutral position and the neutral switch is ON, and the ignition switch 9 is OFF, the process proceeds to Step 209. In other cases, this process is terminated.

  Subsequently, the drive device 13 is instructed to cut (stop) the fuel supply to the engine 1 (step 209), and the electromagnetic clutch 35 is connected, and the compressor 31 is connected from the engine 1 via the belt 36. It connects so that drive is possible (step 210).

  Subsequently, the starter relay 7 is closed to drive the starter 2 (step 211), and the rotation pulse number signal from the engine rotation number sensor 11 is counted to measure the number of rotations of the starter 2 rotating ( Step 212). When it is determined that the starter 2 has rotated by a predetermined number of rotations for a predetermined period (step 213), the execution history F is set to once and the execution history F data is stored in the storage device 41a, and this processing is terminated. (Step 214). These steps 209-213 show the refrigerant | coolant discharge process implemented when predetermined conditions are satisfy | filled.

  In step 213, a predetermined period is set by measuring the elapsed number of revolutions of the engine 1, but the time for driving the starter 2 is set in advance as the predetermined period, and the elapsed time from the start of starter driving. It may be determined whether or not the predetermined period has elapsed.

  As described above, based on the temperature difference between the vehicle room temperature Tr and the minimum outside air temperature Tamin, if it is estimated that the liquefaction phenomenon of the refrigerant for the air conditioner has occurred inside the compressor 31, during this unused period, The starter 2 is driven only once to operate the compressor 31 to generate liquid compression sound of the liquefied refrigerant. In that case, it is a constraint that the transmission is in the neutral position and that the engine 1 is in a fuel cut state, and the starter 2 is driven only when these constraints are satisfied, so that the user is absent. This ensures the safety of the vehicle and prevents unintentional battery exhaustion.

(Other embodiments)
In the above embodiment, the refrigerant liquefaction determination value Tx is obtained using the outside air temperature (outside air temperature information) Ta and the minimum outside air temperature Tamin as shown in FIG. Although it is estimated that the minimum outside air temperature Tamin and the minimum cooling water temperature Twamin of the engine 1 are substantially equal in the early morning, the engine cooling water temperature Twa may be used instead of the outside air temperature Ta.

  In this case, as a flowchart of the engine ECU 4, the flowchart shown in FIG. 6 is used instead of FIG. 3, and as shown in steps 201A, 202A, 203A, and 204A, the coolant temperature Twa from the engine coolant temperature sensor 12 and this time The minimum cooling water temperature Twamin during the unused period of the vehicle is obtained, and when the refrigerant liquefaction determination value Tx, which is the temperature difference between the vehicle room temperature Tr and the minimum cooling water temperature Twamin, is greater than the predetermined temperature To, the liquefaction of the refrigerant The occurrence of the phenomenon is estimated.

  Further, in each of the above embodiments, the number of times the starter 2 is driven is limited to one during one unused period of the vehicle. However, if the capacity of the battery 6 is sufficient, the number of times the starter 2 is driven is predetermined. It may be increased to a plurality of times, or a capacity sensor is added so as to detect the capacity of the battery 6, and the number of times of driving is changed to one time or a predetermined number of times according to the battery capacity. Good.

  Moreover, although the said embodiment is an example which applied this invention to the compressor 31 of the structure driven with the engine 1, instead of this compressor 31, an electric vehicle or engine provided with the electric compressor driven with an electric motor It can also be applied to a hybrid vehicle using a motor as a drive source. In this case, in the flowchart shown in FIG. 4, instead of steps 209 to 213, a step of directly driving the electric motor for a predetermined time and a step of determining that the electric motor has been driven for a predetermined time are provided. When driving is determined, it may be stored as an execution history F (step 214).

1 is a configuration diagram illustrating an overall configuration of a vehicle air conditioner control device according to an embodiment of the present invention. It is a flowchart which shows the base routine of engine ECU4. It is a flowchart which shows the first half part of the soak timer starting process of engine ECU4. It is a flowchart which shows the second half part of the soak timer starting process of engine ECU4. It is explanatory drawing for estimating whether the liquefaction phenomenon in which the refrigerant | coolant for air-conditioners which should be a gas originally will be in a liquid state has generate | occur | produced inside the compressor. It is a flowchart which shows the first half part of the soak timer starting process of engine ECU4 which is other embodiment of this invention. It is explanatory drawing which shows that the temperature of each air conditioner etc. changes from early morning to night.

Explanation of symbols

1 Engine 2 Starter 3 Air-conditioning equipment 4 Engine ECU
5 Air conditioner ECU
6 Battery 7 Starter Relay 8 Power Relay 9 Ignition Switch 10 Neutral Switch 11 Engine Speed Sensor 12 Engine Water Temperature Sensor (Water Temperature Sensor)
13 Drive Device 31 Compressor 41 Microcomputer 41a Storage Device 43 Soak Timer (Soak Timer Means)
51 Outside temperature sensor 52 Inside temperature sensor

Claims (7)

A starter for starting an engine mounted on the vehicle;
Constituting a refrigeration cycle of an air conditioner, driven by the engine; and
Control means for operating the starter and the compressor,
This control means operates the starter when it is estimated that the air-conditioning refrigerant is liquefied in the compressor when the vehicle is not in use.   The control means has a soak timer means for starting the control means at predetermined time intervals when the vehicle is not used, and whether the refrigerant for the air conditioner is liquefied at the predetermined time intervals activated by the soak timer means. The vehicle air conditioner control device according to claim 1, wherein when the liquefaction is estimated, the starter is operated for a predetermined period. An outside air temperature sensor for detecting outside air temperature,
An internal air temperature sensor for detecting a room temperature of the vehicle;
The control means takes in an outside air temperature value from the outside air temperature sensor every predetermined time, and when the outside air temperature value is lower than the stored minimum outside air temperature value, the outside air temperature value is set as the minimum outside air temperature value. Update storage is performed, and when the difference between the lowest outside air temperature value and the room temperature value taken in from the inside air temperature sensor is equal to or greater than a predetermined value, it is estimated that the refrigerant for the air conditioner is liquefied in the compressor. The vehicle air conditioner control device according to claim 2.   The said control means stops the fuel supply to the said engine when operating the said starter when the said vehicle is not used, The vehicle air conditioner control apparatus of Claims 1-3 characterized by the above-mentioned.   The control means permits the starter to be operated when a neutral switch of a transmission for transmitting engine driving force mounted on the vehicle is in a neutral state when operating the starter when the vehicle is not used. The vehicle air conditioner control device according to claim 1, wherein A water temperature sensor for detecting the engine cooling water temperature;
An internal air temperature sensor for detecting a room temperature of the vehicle;
The control means takes in a water temperature value from the water temperature sensor at every predetermined time, and when the water temperature value is lower than the stored minimum water temperature value, updates and stores the water temperature value as the minimum water temperature value. The vehicle-use vehicle according to claim 2, wherein when the difference between a water temperature value and a room temperature value taken from the inside air temperature sensor is equal to or greater than a predetermined value, it is estimated that the air-conditioning refrigerant is liquefied in the compressor. Air conditioner control device. An electric compressor that constitutes a refrigeration cycle of an air conditioner mounted on a vehicle and is driven by an electric motor;
Control means for operating this electric compressor,
When the vehicle is not in use, the control means activates the electric compressor when it is estimated that the air-conditioning refrigerant is liquefied in the electric compressor.

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