JP6854668B2 - Vehicle air conditioner - Google Patents

Description

The present invention relates to a heat pump type air conditioner for air-conditioning the interior of a vehicle, particularly an air conditioner applicable to a hybrid vehicle or an electric vehicle.

Due to the emergence of environmental problems in recent years, hybrid vehicles and electric vehicles have become widespread. As an air conditioner that can be applied to such a vehicle, a compressor that compresses and discharges the refrigerant, an internal condenser that is provided on the vehicle interior side to dissipate the refrigerant, and an internal condenser that is provided on the vehicle interior side are provided. An evaporator that absorbs heat from the refrigerant, an external condenser that is provided outside the vehicle interior to dissipate or absorb heat, a first expansion valve that expands the refrigerant that flows into the external condenser, and a refrigerant that flows into the evaporator. The second expansion valve that inflates the refrigerant, the piping that bypasses the internal condenser and the first expansion valve, and the refrigerant discharged from the compressor flows to the internal condenser, or bypasses the internal condenser and the first expansion valve. A first valve for switching whether to flow directly from the pipe to the external condenser is provided, and the refrigerant discharged from the compressor is flowed to the internal condenser by the first valve to dissipate heat, and the radiated refrigerant is discharged by the first expansion valve. After depressurizing, the heating mode absorbs heat in the external condenser, the refrigerant discharged from the compressor is dissipated in the internal condenser by the first valve, the radiated refrigerant is depressurized by the second expansion valve, and then heat is absorbed in the evaporator. In the dehumidification mode, the refrigerant discharged from the compressor is bypassed by the internal condenser and the first expansion valve by the first valve to flow to the external condenser to dissipate heat, and after depressurizing by the second expansion valve, in the evaporator. Those that switch and execute the cooling mode for absorbing heat have been developed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-23210

As described above, in Patent Document 1, when the cooling mode is switched to, the operating state is such that the refrigerant does not flow through the internal condenser (the radiator in the present application). That is, the outlet on the internal condenser side of the first valve is closed. In this state, the refrigerant is confined in the closed circuit from the first valve (117) to the first expansion valve (119) including the internal condenser (107), so that the compressor immediately after switching to the cooling mode is compressed. When the vessel was stopped, the pressure on the internal condenser side was sometimes higher than the pressure on the discharge side of the compressor.

Here, instead of the first valve, which is a three-way valve, an on-off valve (first on-off valve in the present application) on the internal condenser (radiator in the present application) side and an external condenser (outdoor heat exchanger in the present application). ) Side on-off valve (second on-off valve in the present application) When switching the flow path with two on-off valves, the internal condenser side (radiator) is higher than the pressure on the discharge side of the compressor (compressor in the present application). The pressure on the side) may be higher.

In particular, in Patent Document 1, a PTC heater (109; an auxiliary heating device in the present application) is provided on the leeward side of the internal condenser, but this PTC heater (109) is provided on the leeward side of the internal condenser to generate heat. When this is done, the internal condenser is heated by the heat generated by this PTC heater, so the internal pressure rises, and in the operating state where the load is low and the compressor rotation speed is low, the pressure is higher than the pressure on the discharge side of the compressor. The pressure on the condenser side tends to be higher. In that case, a reverse pressure is applied to the on-off valve on the internal condenser side (the first on-off valve in the present application), which may cause hunting. When hunting occurs on this on-off valve, noise or vibration is generated in the on-off valve. There was a problem that the durability was lowered as well as the occurrence.

Therefore, for example, the pressure on the discharge side of the compressor (compressor in the present application) and the pressure on the internal condenser side (radiator side) are detected by pressure sensors, respectively, and the on-off valve (first on-off valve in the present application) is concerned. ), It is possible to determine the reverse pressure state and deal with it, but each pressure sensor (including the sensor body for detecting pressure and the electronic parts for converting the detected value into voltage and outputting it) There was also a problem that there was a detection error (variation), and although the pressure was actually reverse, it could not be detected accurately and noise and vibration were generated in the on-off valve.

The present invention has been made to solve the above-mentioned conventional technical problems, and effectively eliminates noise and vibration generated by a malfunction of a first on-off valve provided on the inlet side of a radiator. It is an object of the present invention to provide an air conditioner for a vehicle capable of improving the durability of the on-off valve.

The vehicle air conditioner according to claim 1 has a compressor that compresses the refrigerant, an air flow passage through which the air supplied to the vehicle interior flows, and air that dissipates the refrigerant and supplies the air to the vehicle interior from the air flow passage. A radiator for heating the refrigerant, a heat absorber for cooling the air supplied to the passenger compartment from the air flow passage by absorbing the refrigerant, an outdoor heat exchanger provided outside the passenger compartment, and the radiator. An outdoor expansion valve for reducing the pressure of the refrigerant flowing into the outdoor heat exchanger, a first on-off valve provided between the discharge side of the compressor and the inlet side of the radiator, and an upstream of the first on-off valve. Control with a bypass pipe for branching on the side, bypassing the radiator and the outdoor expansion valve, and allowing the refrigerant discharged from the compressor to flow to the outdoor heat exchanger, and a second on-off valve provided in this bypass pipe. A device is provided, and by opening the first on-off valve and closing the second on-off valve by this control device, the refrigerant discharged from the compressor flows to the radiator, and the refrigerant discharged from the radiator is discharged to the outside. The refrigerant discharged from the compressor is discharged by the first operation mode in which the air is passed through the expansion valve to the outdoor heat exchanger, the outdoor expansion valve is fully closed, the first on-off valve is closed, and the second on-off valve is opened. Is flowed to the outdoor heat exchanger by a bypass pipe, and the refrigerant discharged from the outdoor heat exchanger is flowed to the heat absorber by switching the second operation mode, and the control device is executed in the second operation mode. When the rotation speed of the compressor drops below the first predetermined value, the back pressure prevention control for opening the outdoor expansion valve and the first on-off valve is executed.

The vehicle air conditioner according to the second aspect of the present invention is characterized in that, in the above invention, the control device opens the outdoor expansion valve and the first on-off valve at the same time when starting the back pressure prevention control.

The vehicle air conditioner according to claim 3 has a compressor that compresses the refrigerant, an air flow passage through which the air supplied to the vehicle interior flows, and air that dissipates the refrigerant and supplies the air to the vehicle interior from the air flow passage. A radiator for heating the refrigerant, a heat absorber for cooling the air supplied to the passenger compartment from the air flow passage by absorbing the refrigerant, an outdoor heat exchanger provided outside the passenger compartment, and the radiator. An outdoor expansion valve for reducing the pressure of the refrigerant flowing into the outdoor heat exchanger, a first on-off valve provided between the discharge side of the compressor and the inlet side of the radiator, and an upstream of the first on-off valve. Control with a bypass pipe for branching on the side, bypassing the radiator and the outdoor expansion valve, and allowing the refrigerant discharged from the compressor to flow to the outdoor heat exchanger, and a second on-off valve provided in this bypass pipe. A device is provided, and by opening the first on-off valve and closing the second on-off valve by this control device, the refrigerant discharged from the compressor flows to the radiator, and the refrigerant discharged from the radiator is discharged to the outside. The refrigerant discharged from the compressor is discharged by the first operation mode in which the air is passed through the expansion valve to the outdoor heat exchanger, the outdoor expansion valve is fully closed, the first on-off valve is closed, and the second on-off valve is opened. Is flowed to the outdoor heat exchanger by a bypass pipe, and the refrigerant discharged from the outdoor heat exchanger is flowed to the heat absorber by switching the second operation mode, and the control device is executed in the second operation mode. When the rotation speed of the compressor drops below the first predetermined value, the back pressure prevention control for opening either the outdoor expansion valve or the first on-off valve is executed.

The vehicle air conditioner according to the fourth aspect of the present invention is the second predetermined value in which the rotation speed of the compressor is higher than the first predetermined value when the control device is executing the back pressure prevention control in each of the above inventions. When the value rises above the value, the back pressure prevention control is terminated, the outdoor expansion valve is fully closed, and the first on-off valve is returned to the closed state.

The vehicle air conditioner according to claim 5 includes a discharge pressure sensor that detects and outputs the discharge refrigerant pressure of the compressor and a radiator pressure sensor that detects and outputs the refrigerant pressure of the radiator in each of the above inventions. In the second operation mode, the control device has a discharge pressure Pd output by the discharge pressure sensor higher than the radiator pressure PCI output by the radiator pressure sensor, and the difference is between the discharge pressure sensor and the radiator pressure sensor. When it is equal to or more than the maximum error value derived from the detection error, the back pressure prevention control is not executed.

The vehicle air conditioner according to claim 6 includes an auxiliary heating device for heating the air supplied from the air flow passage to the vehicle interior in each of the above inventions, and the first operation mode is discharged from the compressor. A heating mode in which the heat is dissipated by a radiator, the dissipated refrigerant is decompressed by an outdoor expansion valve, and then heat is absorbed by an outdoor heat exchanger, and the refrigerant discharged from the compressor is discharged from the radiator to an outdoor heat exchanger. A dehumidifying cooling mode in which the heat is dissipated by the radiator and the outdoor heat exchanger, the radiated refrigerant is decompressed, and then the heat is absorbed by the heat absorber, and the refrigerant discharged from the compressor is exchanged from the radiator to the outdoor heat. One of the cooling modes in which the heat is dissipated by the outdoor heat exchanger, the heat is decompressed, and then the heat is absorbed by the heat absorber, or a combination thereof, or all of them. In the second operation mode, the refrigerant discharged from the compressor is flowed from the bypass pipe to the outdoor heat exchanger to dissipate heat, the dissipated refrigerant is depressurized, and then heat is absorbed by the heat exchanger, and the auxiliary heating device is used. Either the dehumidifying / heating mode that generates heat or the maximum cooling mode in which the refrigerant discharged from the compressor is flowed from the bypass pipe to the outdoor heat exchanger to dissipate heat, the dissipated refrigerant is depressurized, and then the heat is absorbed by the heat exchanger. Or all of them.

In the vehicle air conditioner according to claim 7, in the above invention, the auxiliary heating device is provided on the upstream side of the radiator with respect to the air flow in the air flow passage, and the second operation mode is dehumidification. It is characterized by being in a heating mode.

According to the inventions of claims 1 and 3, a compressor that compresses the refrigerant, an air flow passage through which the air supplied to the vehicle interior flows, and air that dissipates the refrigerant and supplies the air to the vehicle interior from the air flow passage. A radiator for heating, a heat exchanger for absorbing the refrigerant and cooling the air supplied to the passenger compartment from the air flow passage, an outdoor heat exchanger provided outside the passenger compartment, and the radiator. An outdoor expansion valve for reducing the pressure of the refrigerant flowing into the outdoor heat exchanger, a first on-off valve provided between the discharge side of the compressor and the inlet side of the radiator, and an upstream of the first on-off valve. A bypass pipe that branches on the side and bypasses the radiator and the outdoor expansion valve to allow the refrigerant discharged from the compressor to flow to the outdoor heat exchanger, and a second on-off valve provided in this bypass pipe. A device is provided, and by opening the first on-off valve and closing the second on-off valve by this control device, the refrigerant discharged from the compressor flows to the radiator, and the refrigerant discharged from the radiator is discharged to the outside. The refrigerant discharged from the compressor by the first operation mode in which the air flows through the expansion valve to the outdoor heat exchanger, the outdoor expansion valve is fully closed, the first on-off valve is closed, and the second on-off valve is opened. In the vehicle air conditioner, which is executed by switching the second operation mode in which the air is flown to the outdoor heat exchanger by the bypass pipe and the refrigerant discharged from the outdoor heat exchanger is flowed to the heat absorber, the control device is operated in the second operation. When the number of revolutions of the compressor drops below the first predetermined value in the mode, the outdoor expansion valve and / or the back pressure prevention control for opening the first on-off valve is executed, so that the first opening and closing is performed. In the second operation mode in which the valve is closed and the second on-off valve is opened, when the number of revolutions of the compressor decreases and the first on-off valve is likely to be subjected to a back pressure, the outdoor operation is performed. The expansion valve and the first on-off valve will be opened.

As a result, the inlet side and the outlet side of the first on-off valve are equalized, so that it is possible to eliminate the inconvenience of applying a back pressure to the first on-off valve, and hunting occurs in the first on-off valve. It becomes possible to solve or suppress the inconvenience of generating noise and vibration and the problem of deterioration of the durability of the first on-off valve.

In particular, in the invention of claim 1, since the control device opens both the outdoor expansion valve and the first on-off valve in the back pressure prevention control, the inlet side and the outlet side of the first on-off valve are quickly equalized. It is possible to effectively eliminate the inconvenience of applying reverse pressure to the first on-off valve. Here, when the outdoor expansion valve and the first on-off valve are opened, if the outdoor expansion valve is opened before the first on-off valve, there is a risk that a flow noise will be generated because the refrigerant gradually flows through the first on-off valve. However, if the outdoor expansion valve and the first on-off valve are opened at the same time when the back pressure prevention control is started by the control device as in the invention of claim 2, such inconvenience can be prevented or suppressed. Will be able to.

Then, when the control device is executing the back pressure prevention control as in the invention of claim 4, when the rotation speed of the compressor rises to a second predetermined value higher than the first predetermined value, the back pressure is increased. If the prevention control is terminated and the outdoor expansion valve is fully closed and the first on-off valve is returned to the closed state, the rotation speed of the compressor increases and a back pressure is applied to the first on-off valve. Depending on the difficulty, it is possible to return to the operating state of the original second operation mode without any trouble.

Further, as in the invention of claim 5, a discharge pressure sensor that detects and outputs the discharge refrigerant pressure of the compressor and a radiator pressure sensor that detects and outputs the refrigerant pressure of the radiator is provided, and the control device is the second. In the operation mode, the discharge pressure Pd output by the discharge pressure sensor is higher than the radiator pressure PCI output by the radiator pressure sensor, and the difference is the maximum error value derived from the detection error of the discharge pressure sensor and the radiator pressure sensor. In the above case, if the back pressure prevention control is not executed, the back pressure prevention control is clearly performed in the operating state where the back pressure is not applied to the first on-off valve even if the detection error of each pressure sensor is taken into consideration. By not performing the above, it is possible to avoid unnecessary opening of the outdoor expansion valve and the first on-off valve, and to smoothly continue the second operation mode.

Here, in the first operation mode of the vehicle air conditioner of each of the above inventions, as in the invention of claim 6, the refrigerant discharged from the compressor is radiated by the radiator, and the radiated refrigerant is expanded outdoors. A heating mode in which heat is absorbed by an outdoor heat exchanger after depressurizing with a valve, and a refrigerant discharged from a compressor is flowed from a radiator to an outdoor heat exchanger to dissipate heat through the radiator and the outdoor heat exchanger to dissipate heat. The dehumidifying and cooling mode in which the heat is absorbed by the heat absorber after depressurizing the refrigerant, and the refrigerant discharged from the compressor is flowed from the radiator to the outdoor heat exchanger to dissipate heat in the outdoor heat exchanger and dissipate heat. One of the cooling modes in which the heat is absorbed by the heat exchanger after the refrigerant is depressurized, or a combination thereof, or all of them, and the second operation mode bypasses the refrigerant discharged from the compressor. The heat is radiated by flowing from the pipe to the outdoor heat exchanger, the radiated refrigerant is depressurized, and then the heat is absorbed by the heat absorber, and the auxiliary heating device for heating the air supplied from the air flow passage to the passenger compartment is heated. Either the dehumidifying / heating mode or the maximum cooling mode in which the refrigerant discharged from the compressor is flowed from the bypass pipe to the outdoor heat exchanger to dissipate heat, the dissipated refrigerant is depressurized, and then the heat is absorbed by the heat exchanger. Or all of them.

When the auxiliary heating device is provided on the upstream side of the radiator with respect to the air flow in the air flow passage as in the invention of claim 7 and the dehumidifying and heating mode is executed as the second operation mode, the radiator is assisted. Since the internal pressure rises due to the heat generated by the heating device, the reverse pressure is likely to be applied to the first on-off valve in the operating state where the compressor rotation speed is low. It will be extremely effective.

It is a block diagram of the air conditioner for a vehicle of one Embodiment to which this invention was applied (heating mode, dehumidifying heating mode, dehumidifying cooling mode and cooling mode). It is a block diagram of the electric circuit of the controller of the air conditioner for a vehicle of FIG. It is a block diagram in the MAX cooling mode (maximum cooling mode) of the air conditioner for a vehicle of FIG. It is a timing chart of each apparatus explaining an example of the back pressure prevention control executed by the controller of FIG. 2 in a dehumidifying heating mode. It is another timing chart of each device explaining an example of the back pressure prevention control executed by the controller of FIG. 2 in a dehumidifying heating mode. It is a timing chart of each apparatus explaining another example of the back pressure prevention control executed by the controller of FIG. 2 in a dehumidifying heating mode. It is a timing chart of each apparatus explaining another example of the back pressure prevention control executed by the controller of FIG. 2 in a dehumidifying heating mode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a configuration diagram of an air conditioner 1 for a vehicle according to an embodiment of the present invention. The vehicle of the embodiment to which the present invention is applied is an electric vehicle (EV) in which an engine (internal combustion engine) is not mounted, and travels by driving an electric motor for traveling with electric power charged in a battery. Yes (neither is shown), and the vehicle air conditioner 1 of the present invention is also driven by the power of the battery. That is, the vehicle air conditioner 1 of the embodiment performs the heating mode by the heat pump operation using the refrigerant circuit in the electric vehicle that cannot be heated by the waste heat of the engine, and further, the dehumidifying heating mode, the dehumidifying cooling mode, the cooling mode, Each operation mode of the MAX cooling mode (maximum cooling mode) and the auxiliary heater independent mode is selectively executed.

It should be noted that the present invention is effective not only for electric vehicles as vehicles but also for so-called hybrid vehicles that use an engine and an electric motor for traveling, and further, it can be applied to ordinary vehicles traveling with an engine. Needless to say. Further, the heating mode, the dehumidifying / cooling mode, and the cooling mode are the first operation mode in the present invention, the dehumidifying / heating mode, and the MAX cooling mode are the second operation modes in the present invention.

The vehicle air conditioner 1 of the embodiment air-conditions (heating, cooling, dehumidifying, and ventilating) the interior of the electric vehicle, and includes an electric compressor 2 that compresses the refrigerant and the interior air of the vehicle. Is provided in the air flow passage 3 of the HVAC unit 10 through which air is circulated, and the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows in through the refrigerant pipe 13G, and the radiator 4 dissipates this refrigerant into the vehicle interior. An outdoor expansion valve 6 composed of an electric valve that decompresses and expands the refrigerant during heating, and a heat exchange between the refrigerant and the outside air so as to be provided outside the vehicle interior and function as a radiator during cooling and as an evaporator during heating. An indoor expansion valve 8 including an outdoor heat exchanger 7 for reducing the pressure and expansion of the refrigerant, and a heat absorber 9 provided in the air flow passage 3 for absorbing heat from the inside and outside of the vehicle during cooling and dehumidification. And the accumulator 12 and the like are sequentially connected by the refrigerant pipe 13, and the refrigerant circuit R is configured.

The refrigerant circuit R is filled with a predetermined amount of refrigerant and lubricating oil. The outdoor heat exchanger 7 is provided with an outdoor blower 15. The outdoor blower 15 forcibly ventilates the outdoor air to the outdoor heat exchanger 7 to exchange heat between the outside air and the refrigerant, whereby the outdoor air is outdoors even when the vehicle is stopped (that is, the vehicle speed is 0 km / h). The heat exchanger 7 is configured to ventilate outside air.

Further, the outdoor heat exchanger 7 has a receiver dryer portion 14 and a supercooling portion 16 in sequence on the downstream side of the refrigerant, and the refrigerant pipe 13A coming out of the outdoor heat exchanger 7 receives the receiver via an electromagnetic valve 17 opened during cooling. The refrigerant pipe 13B on the outlet side of the supercooling unit 16 is connected to the dryer unit 14 and is connected to the inlet side of the heat exchanger 9 via the indoor expansion valve 8. The receiver dryer section 14 and the supercooling section 16 structurally form a part of the outdoor heat exchanger 7.

Further, the refrigerant pipe 13B between the supercooling unit 16 and the indoor expansion valve 8 is provided in a heat exchange relationship with the refrigerant pipe 13C on the outlet side of the heat absorber 9, and both constitute the internal heat exchanger 19. As a result, the refrigerant flowing into the indoor expansion valve 8 via the refrigerant pipe 13B is configured to be cooled (supercooled) by the low-temperature refrigerant leaving the heat absorber 9.

Further, the refrigerant pipe 13A coming out of the outdoor heat exchanger 7 is branched into the refrigerant pipe 13D, and the branched refrigerant pipe 13D is on the downstream side of the internal heat exchanger 19 via the electromagnetic valve 21 opened at the time of heating. Is connected to the refrigerant pipe 13C in the above. The refrigerant pipe 13C is connected to the accumulator 12, and the accumulator 12 is connected to the refrigerant suction side of the compressor 2. Further, the refrigerant pipe 13E on the outlet side of the radiator 4 is connected to the inlet side of the outdoor heat exchanger 7 via the outdoor expansion valve 6.

Further, the refrigerant pipe 13G between the discharge side of the compressor 2 and the inlet side of the radiator 4 has a solenoid valve 30 that is closed during dehumidifying heating and MAX cooling, which will be described later (first on-off valve in the present application: solenoid for reheating). A valve) is installed. In this case, the refrigerant pipe 13G branches to the bypass pipe 35 on the upstream side of the solenoid valve 30, and the bypass pipe 35 is connected to the solenoid valve 40 (the second on-off valve in the present application) which is opened during dehumidifying heating and MAX cooling. : A solenoid valve for bypass) is provided, and is communicated with the refrigerant pipe 13E on the downstream side of the outdoor expansion valve 6 via the solenoid valve 40. The bypass device 45 is composed of the bypass pipe 35, the solenoid valve 30, and the solenoid valve 40.

By configuring the bypass device 45 with such a bypass pipe 35, a solenoid valve 30, and a solenoid valve 40, a dehumidifying / heating mode or MAX in which the refrigerant discharged from the compressor 2 directly flows into the outdoor heat exchanger 7 as described later. It becomes possible to smoothly switch between the cooling mode and the heating mode, the dehumidifying cooling mode, and the cooling mode in which the refrigerant discharged from the compressor 2 flows into the radiator 4.

Further, in the air flow passage 3 on the air upstream side of the heat absorber 9, each suction port of the outside air suction port and the inside air suction port is formed (represented by the suction port 25 in FIG. 1), and this suction port is formed. The suction switching damper 26 for switching the air introduced into the air flow passage 3 into the inside air (inside air circulation mode), which is the air inside the vehicle interior, and the outside air (outside air introduction mode), which is the air outside the vehicle interior, is provided. There is. Further, an indoor blower fan 27 for supplying the introduced inside air and outside air to the air flow passage 3 is provided on the air downstream side of the suction switching damper 26.

Further, in FIG. 1, 23 is an auxiliary heater as an auxiliary heating device provided in the vehicle air conditioner 1 of the embodiment. The auxiliary heater 23 of the embodiment is composed of a PTC heater which is an electric heater, and is provided in the air flow passage 3 which is on the air upstream side of the radiator 4 with respect to the air flow of the air flow passage 3. There is. Then, when the auxiliary heater 23 is energized to generate heat, the air in the air flow passage 3 flowing into the radiator 4 via the endothermic absorber 9 is heated. That is, the auxiliary heater 23 serves as a so-called heater core, which heats or complements the interior of the vehicle.

Further, in the air flow passage 3 on the air upstream side of the auxiliary heater 23, the air (inside air or outside air) in the air flow passage 3 after flowing into the air flow passage 3 and passing through the heat absorber 9 is assisted. An air mix damper 28 for adjusting the ratio of ventilation to the heater 23 and the radiator 4 is provided. Further, FOOT (foot), VENT (vent), and DEF (diff) outlets (represented by outlet 29 in FIG. 1) are formed in the air flow passage 3 on the air downstream side of the radiator 4. The outlet 29 is provided with an outlet switching damper 31 that switches and controls the blowing of air from each of the outlets.

Next, in FIG. 2, reference numeral 32 denotes a controller (ECU) as a control device composed of a microcomputer which is an example of a computer provided with a processor, and the outside air temperature (Tam) of the vehicle is detected at the input of the controller 32. The outside air temperature sensor 33, the outside air humidity sensor 34 that detects the outside air humidity, the HVAC suction temperature sensor 36 that detects the temperature of the air sucked into the air flow passage 3 from the suction port 25, and the air (inside air) in the vehicle interior. The inside air temperature sensor 37 that detects the temperature, the inside air humidity sensor 38 that detects the humidity of the air inside the vehicle, the indoor CO ₂ concentration sensor 39 that detects the carbon dioxide concentration inside the vehicle, and the air outlet 29 blows out into the vehicle interior. A blowout temperature sensor 41 that detects the temperature of the air to be generated, a discharge pressure sensor 42 that detects the discharge refrigerant pressure (discharge pressure Pd) of the compressor 2, and a discharge temperature sensor 43 that detects the discharge refrigerant temperature of the compressor 2. , The suction temperature sensor 55 that detects the suction refrigerant temperature of the compressor 2, the radiator inlet temperature sensor 44 that detects the refrigerant temperature at the inlet of the radiator 4 (radiator inlet temperature TCIin), and the refrigerant at the outlet of the radiator 4. The radiator outlet temperature sensor 46 that detects the temperature (radiator outlet temperature TCIout) and the refrigerant pressure of the radiator 4 (the pressure of the refrigerant in the radiator 4 or immediately after leaving the radiator 4: radiator pressure PCI). The radiator pressure sensor 47 that detects the temperature of the heat absorber 9 and the heat absorber temperature sensor 48 that detects the temperature of the heat absorber 9 (the temperature of the air that has passed through the heat absorber 9 or the temperature of the heat absorber 9 itself: the heat absorber temperature Te), and the heat absorber. A heat absorber pressure sensor 49 for detecting the refrigerant pressure of the device 9 (the pressure of the refrigerant in the heat absorber 9 or immediately after leaving the heat absorber 9) and, for example, a photosensor type for detecting the amount of solar radiation into the vehicle interior. From the solar radiation sensor 51, the vehicle speed sensor 52 for detecting the moving speed (vehicle speed) of the vehicle, the air conditioning (air conditioner) operation unit 53 for setting the set temperature and the switching of the operation mode, and the outdoor heat exchanger 7. The outdoor heat exchanger temperature sensor 54 that detects the temperature of the refrigerant immediately after it is discharged (outdoor heat exchanger temperature TXO) and the refrigerant pressure of the outdoor heat exchanger 7 (inside the outdoor heat exchanger 7 or the outdoor heat exchanger 7). Each output of the outdoor heat exchanger pressure sensor 56 that detects the pressure of the refrigerant immediately after exiting from: outdoor heat exchanger pressure PXO) is connected. Further, at the input of the controller 32, an auxiliary heater temperature sensor that detects the temperature of the auxiliary heater 23 (the temperature of the air immediately after being heated by the auxiliary heater 23 or the temperature of the auxiliary heater 23 itself: the auxiliary heater temperature Tptc). Fifty outputs are also connected.

In the present application, each sensor is treated as including a sensor main body for detecting temperature and pressure, and an electronic component for converting the detected value of the sensor main body into a voltage and outputting it to the controller 32.

On the other hand, the output of the controller 32 includes the compressor 2, the outdoor blower 15, the indoor blower (blower fan) 27, the suction switching damper 26, the air mix damper 28, the air outlet switching damper 31, and the outdoor expansion. Valve 6, indoor expansion valve 8 and auxiliary heater 23, solenoid valve 30 (for reheating), solenoid valve 17 (for cooling), solenoid valve 21 (for heating), solenoid valve 40 (for bypass) are connected. Has been done. Then, the controller 32 controls these based on the output of each sensor and the setting input by the air conditioner operation unit 53.

With the above configuration, the operation of the vehicle air conditioner 1 of the embodiment will be described next. In the embodiment, the controller 32 switches and executes each operation mode of the heating mode, the dehumidifying heating mode, the dehumidifying cooling mode, the cooling mode, the MAX cooling mode (maximum cooling mode), and the auxiliary heater independent mode. First, the outline of the flow and control of the refrigerant in each operation mode will be described.

(1) Heating mode (first operation mode)
When the heating mode is selected by the controller 32 (auto mode) or by manual operation (manual mode) to the air conditioning operation unit 53, the controller 32 opens the heating solenoid valve 21 and closes the cooling solenoid valve 17. .. Further, the solenoid valve 30 for reheating is opened, and the solenoid valve 40 for bypass is closed.

Then, the compressor 2 and the blowers 15 and 27 are operated, and the air mix damper 28 is blown out from the indoor blower 27 and passed through the heat absorber 9 in the air flow passage 3 as shown by the broken line in FIG. The air is ventilated to the auxiliary heater 23 and the radiator 4. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 flows into the radiator 4 from the refrigerant pipe 13G via the solenoid valve 30. Since the air in the air flow passage 3 is ventilated through the radiator 4, the air in the air flow passage 3 is the high-temperature refrigerant in the radiator 4 (when the auxiliary heater 23 operates, the auxiliary heater 23 and the radiator 4 are used. ), On the other hand, the refrigerant in the radiator 4 is deprived of heat by the air and cooled to be condensed.

The refrigerant liquefied in the radiator 4 exits the radiator 4 and then reaches the outdoor expansion valve 6 via the refrigerant pipe 13E. The refrigerant that has flowed into the outdoor expansion valve 6 is decompressed there, and then flows into the outdoor heat exchanger 7. The refrigerant that has flowed into the outdoor heat exchanger 7 evaporates and draws heat by running or from the outside air that is ventilated by the outdoor blower 15. That is, the refrigerant circuit R serves as a heat pump. Then, the low-temperature refrigerant that has exited the outdoor heat exchanger 7 enters the accumulator 12 from the refrigerant pipe 13C via the refrigerant pipe 13A, the solenoid valve 21, and the refrigerant pipe 13D, and after gas-liquid separation there, the gas refrigerant is used in the compressor 2. Repeat the circulation sucked into. That is, the refrigerant discharged from the outdoor heat exchanger 7 flows to the accumulator 12 without passing through the heat absorber 9. Then, since the air heated by the radiator 4 (when the auxiliary heater 23 operates, the auxiliary heater 23 and the radiator 4) is blown out from the air outlet 29, the interior of the vehicle is heated by this. Become.

The controller 32 calculates the target radiator pressure PCO (target value of the radiator pressure PCI) from the target radiator temperature TCO (target value of the radiator temperature TH) calculated from the target blowout temperature TAO described later, and this target heat dissipation. The rotation speed NC of the compressor 2 is controlled based on the instrument pressure PCO and the refrigerant pressure of the radiator 4 (radiator pressure PCI; high pressure of the refrigerant circuit R) detected by the radiator pressure sensor 47. Further, the controller 32 is based on the radiator inlet temperature TCIin detected by the radiator inlet temperature sensor 44, the radiator outlet temperature TCIout detected by the radiator outlet temperature sensor 46, and the radiator pressure PCI detected by the radiator pressure sensor 47. The valve opening degree of the outdoor expansion valve 6 is controlled, and the supercooling degree SC of the refrigerant at the outlet of the radiator 4 is controlled. The target radiator temperature TCO is basically TCO = TAO, but a predetermined control limit is provided.

Further, in this heating mode, when the heating capacity of the radiator 4 is insufficient for the heating capacity required for the air conditioning in the vehicle interior, the controller 32 assists to supplement the insufficient heating capacity with the heat generated by the auxiliary heater 23. Controls the energization of the heater 23. As a result, comfortable vehicle interior heating is realized, and frost formation of the outdoor heat exchanger 7 is also suppressed. At this time, since the auxiliary heater 23 is arranged on the upstream side of the air of the radiator 4, the air flowing through the air flow passage 3 is ventilated to the auxiliary heater 23 in front of the radiator 4.

Here, if the auxiliary heater 23 is arranged on the downstream side of the air of the radiator 4, when the auxiliary heater 23 is configured by the PTC heater as in the embodiment, the temperature of the air flowing into the auxiliary heater 23 is the radiator. Since the temperature is increased by 4, the resistance value of the PTC heater increases, the current value also decreases, and the amount of heat generated decreases. However, by arranging the auxiliary heater 23 on the upstream side of the air of the radiator 4, the example of the embodiment As described above, the ability of the auxiliary heater 23 composed of the PTC heater can be fully exhibited.

(2) Dehumidifying and heating mode (second operation mode)
Next, in the dehumidifying / heating mode, the controller 32 opens the solenoid valve 17 and closes the solenoid valve 21. Further, the solenoid valve 30 is closed, the solenoid valve 40 is opened, and the valve opening degree of the outdoor expansion valve 6 is fully closed. Then, the compressor 2 and the blowers 15 and 27 are operated, and the air mix damper 28 is blown out from the indoor blower 27 and passed through the heat absorber 9 in the air flow passage 3 as shown by the broken line in FIG. The air is ventilated to the auxiliary heater 23 and the radiator 4.

As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 to the refrigerant pipe 13G flows into the bypass pipe 35 without going to the radiator 4, passes through the solenoid valve 40, and flows into the refrigerant pipe on the downstream side of the outdoor expansion valve 6. It will reach 13E. At this time, since the outdoor expansion valve 6 is fully closed, the refrigerant flows into the outdoor heat exchanger 7. The refrigerant flowing into the outdoor heat exchanger 7 is air-cooled and condensed by traveling there or by the outside air ventilated by the outdoor blower 15. The refrigerant exiting the outdoor heat exchanger 7 flows sequentially from the refrigerant pipe 13A through the solenoid valve 17 to the receiver dryer section 14 and the supercooling section 16. Here the refrigerant is supercooled.

The refrigerant exiting the supercooling section 16 of the outdoor heat exchanger 7 enters the refrigerant pipe 13B, passes through the internal heat exchanger 19, and reaches the indoor expansion valve 8. After the refrigerant is depressurized by the indoor expansion valve 8, it flows into the heat absorber 9 and evaporates. The air blown out from the indoor blower 27 is cooled by the endothermic action at this time, and the moisture in the air condenses and adheres to the heat absorber 9, so that the air in the air flow passage 3 is cooled and It is dehumidified. The refrigerant evaporated in the heat absorber 9 passes through the internal heat exchanger 19 and reaches the accumulator 12 via the refrigerant pipe 13C, and repeats the circulation of being sucked into the compressor 2 through the accumulator 12.

At this time, since the valve opening degree of the outdoor expansion valve 6 is fully closed, it is possible to suppress or prevent the inconvenience that the refrigerant discharged from the compressor 2 flows back from the outdoor expansion valve 6 into the radiator 4. It becomes. As a result, it becomes possible to suppress or eliminate the decrease in the amount of refrigerant circulation and secure the air conditioning capacity. Further, in this dehumidifying / heating mode, the controller 32 energizes the auxiliary heater 23 to generate heat. As a result, the air cooled and dehumidified by the heat absorber 9 is further heated in the process of passing through the auxiliary heater 23, and the temperature rises, so that the dehumidifying and heating of the vehicle interior is performed.

The controller 32 controls the rotation speed NC of the compressor 2 based on the temperature of the endothermic 9 (heat absorber temperature Te) detected by the endothermic temperature sensor 48 and the target endothermic temperature TEO which is the target value thereof, and also controls the rotation speed NC of the compressor 2. By controlling the energization (heat generation) of the auxiliary heater 23 based on the auxiliary heater temperature Tptc detected by the temperature sensor 50 and the above-mentioned target radiator temperature TCO, the air in the endothermic 9 can be appropriately cooled and dehumidified. The heating by the auxiliary heater 23 accurately prevents the temperature of the air blown from the outlet 29 into the vehicle interior from dropping.

As a result, it becomes possible to control the temperature to an appropriate heating temperature while dehumidifying the air blown into the vehicle interior, and it becomes possible to realize comfortable and efficient dehumidification heating in the vehicle interior. Further, as described above, in the dehumidifying / heating mode, the air mix damper 28 is in a state of ventilating all the air in the air flow passage 3 to the auxiliary heater 23 and the radiator 4, so that the air passing through the heat absorber 9 is efficiently assisted. It becomes possible to improve energy saving by heating with the heater 23 and also to improve the controllability of dehumidifying, heating and air conditioning.

By arranging the auxiliary heater 23 on the upstream side of the air of the radiator 4 as in the embodiment, when the auxiliary heater 23 generates heat, the heated air flows into the radiator 4, so that the radiator Although No. 4 is heated, the safety (electric shock) of the occupant is improved as compared with the case where the auxiliary heater 23 is arranged on the downstream side of the air of the radiator 4.

(3) Dehumidifying and cooling mode (first operation mode)
Next, in the dehumidifying / cooling mode, the controller 32 opens the solenoid valve 17 and closes the solenoid valve 21. Further, the solenoid valve 30 is opened and the solenoid valve 40 is closed. Then, the compressor 2 and the blowers 15 and 27 are operated, and the air mix damper 28 is blown out from the indoor blower 27 and passed through the heat absorber 9 in the air flow passage 3 as shown by the broken line in FIG. The air is ventilated to the auxiliary heater 23 and the radiator 4. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 flows into the radiator 4 from the refrigerant pipe 13G via the solenoid valve 30. Since the air in the air flow passage 3 is ventilated to the radiator 4, the air in the air flow passage 3 is heated by the high temperature refrigerant in the radiator 4, while the refrigerant in the radiator 4 heats the air. It is deprived, cooled, and condensed.

The refrigerant exiting the radiator 4 reaches the outdoor expansion valve 6 via the refrigerant pipe 13E, and flows into the outdoor heat exchanger 7 via the outdoor expansion valve 6 which is slightly opened and controlled. The refrigerant flowing into the outdoor heat exchanger 7 is air-cooled and condensed by traveling there or by the outside air ventilated by the outdoor blower 15. The refrigerant exiting the outdoor heat exchanger 7 flows sequentially from the refrigerant pipe 13A through the solenoid valve 17 to the receiver dryer section 14 and the supercooling section 16. Here the refrigerant is supercooled.

The refrigerant exiting the supercooling section 16 of the outdoor heat exchanger 7 enters the refrigerant pipe 13B, passes through the internal heat exchanger 19, and reaches the indoor expansion valve 8. After the refrigerant is depressurized by the indoor expansion valve 8, it flows into the heat absorber 9 and evaporates. Due to the endothermic action at this time, the moisture in the air blown out from the indoor blower 27 condenses and adheres to the heat absorber 9, so that the air is cooled and dehumidified.

The refrigerant evaporated in the heat absorber 9 passes through the internal heat exchanger 19 and reaches the accumulator 12 via the refrigerant pipe 13C, and repeats the circulation of being sucked into the compressor 2 through the accumulator 12. In this dehumidifying / cooling mode, since the controller 32 does not energize the auxiliary heater 23, it is cooled by the heat absorber 9, and the dehumidified air is reheated in the process of passing through the radiator 4 (the heat dissipation capacity is lower than that during heating). To. As a result, the interior of the vehicle is dehumidified and cooled.

The controller 32 controls the rotation speed NC of the compressor 2 based on the temperature of the heat absorber 9 (heat absorber temperature Te) detected by the heat absorber temperature sensor 48, and expands outdoors based on the high pressure of the refrigerant circuit R described above. The valve opening degree of the valve 6 is controlled, and the refrigerant pressure (radiator pressure PCI) of the radiator 4 is controlled.

(4) Cooling mode (first operation mode)
Next, in the cooling mode, the controller 32 fully opens the valve opening degree of the outdoor expansion valve 6 in the state of the dehumidifying cooling mode. The controller 32 controls the air mix damper 28, and as shown by the solid line in FIG. 1, the air in the air flow passage 3 after being blown out from the indoor blower 27 and passing through the heat absorber 9 dissipates heat to the auxiliary heater 23. Adjust the ratio of ventilation to the vessel 4. Further, the controller 32 does not energize the auxiliary heater 23.

As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 flows into the radiator 4 from the refrigerant pipe 13G via the solenoid valve 30, and the refrigerant discharged from the radiator 4 passes through the refrigerant pipe 13E and the outdoor expansion valve 6 To. At this time, since the outdoor expansion valve 6 is fully opened, the refrigerant passes through it and flows into the outdoor heat exchanger 7 as it is, where it is air-cooled by running or by the outside air ventilated by the outdoor blower 15 and condensed. Liquefaction. The refrigerant exiting the outdoor heat exchanger 7 flows sequentially from the refrigerant pipe 13A through the solenoid valve 17 to the receiver dryer section 14 and the supercooling section 16. Here the refrigerant is supercooled.

The refrigerant exiting the supercooling section 16 of the outdoor heat exchanger 7 enters the refrigerant pipe 13B, passes through the internal heat exchanger 19, and reaches the indoor expansion valve 8. After the refrigerant is depressurized by the indoor expansion valve 8, it flows into the heat absorber 9 and evaporates. The air blown out from the indoor blower 27 is cooled by the endothermic action at this time. Further, the moisture in the air condenses and adheres to the heat absorber 9.

The refrigerant evaporated in the heat absorber 9 passes through the internal heat exchanger 19 and reaches the accumulator 12 via the refrigerant pipe 13C, and repeats the circulation of being sucked into the compressor 2 through the accumulator 12. Since the dehumidified air cooled by the heat absorber 9 is blown out into the vehicle interior from the air outlet 29 (a part of the air passes through the radiator 4 to exchange heat), the interior of the vehicle is cooled. become. Further, in this cooling mode, the controller 32 rotates the compressor 2 based on the temperature of the endothermic 9 (heat absorber temperature Te) detected by the heat absorber temperature sensor 48 and the target heat absorber temperature TEO which is the target value thereof. Control NC.

(5) MAX cooling mode (maximum cooling mode: second operation mode)
Next, in the MAX cooling mode as the maximum cooling mode, the controller 32 opens the solenoid valve 17 and closes the solenoid valve 21. Further, the solenoid valve 30 is closed, the solenoid valve 40 is opened, and the valve opening degree of the outdoor expansion valve 6 is fully closed. Then, the compressor 2 and the blowers 15 and 27 are operated, and the air mix damper 28 is in a state where the air in the air flow passage 3 is not ventilated to the auxiliary heater 23 and the radiator 4 as shown in FIG. However, there is no problem even if there is some ventilation. Further, the controller 32 does not energize the auxiliary heater 23.

As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 to the refrigerant pipe 13G flows into the bypass pipe 35 without going to the radiator 4, passes through the solenoid valve 40, and flows into the refrigerant pipe on the downstream side of the outdoor expansion valve 6. It will reach 13E. At this time, since the outdoor expansion valve 6 is fully closed, the refrigerant flows into the outdoor heat exchanger 7. The refrigerant flowing into the outdoor heat exchanger 7 is air-cooled and condensed by traveling there or by the outside air ventilated by the outdoor blower 15. The refrigerant exiting the outdoor heat exchanger 7 flows sequentially from the refrigerant pipe 13A through the solenoid valve 17 to the receiver dryer section 14 and the supercooling section 16. Here the refrigerant is supercooled.

The refrigerant exiting the supercooling section 16 of the outdoor heat exchanger 7 enters the refrigerant pipe 13B, passes through the internal heat exchanger 19, and reaches the indoor expansion valve 8. After the refrigerant is depressurized by the indoor expansion valve 8, it flows into the heat absorber 9 and evaporates. The air blown out from the indoor blower 27 is cooled by the endothermic action at this time. Further, since the moisture in the air condenses and adheres to the heat absorber 9, the air in the air flow passage 3 is dehumidified. The refrigerant evaporated in the heat absorber 9 passes through the internal heat exchanger 19 and reaches the accumulator 12 via the refrigerant pipe 13C, and repeats the circulation of being sucked into the compressor 2 through the accumulator 12. At this time, since the outdoor expansion valve 6 is fully closed, it is possible to suppress or prevent the inconvenience that the refrigerant discharged from the compressor 2 flows back from the outdoor expansion valve 6 into the radiator 4. .. As a result, it becomes possible to suppress or eliminate the decrease in the amount of refrigerant circulation and secure the air conditioning capacity.

Here, since the high-temperature refrigerant is flowing through the radiator 4 in the above-mentioned cooling mode, direct heat conduction from the radiator 4 to the HVAC unit 10 is not a little generated, but in this MAX cooling mode, the refrigerant is transferred to the radiator 4. Does not flow, so that the heat transferred from the radiator 4 to the HVAC unit 10 does not heat the air in the air flow passage 3 from the heat absorber 9. Therefore, the interior of the vehicle is strongly cooled, and particularly in an environment where the outside air temperature Tam is high, the interior of the vehicle can be quickly cooled to realize comfortable air conditioning in the vehicle interior. Further, even in this MAX cooling mode, the controller 32 rotates the compressor 2 based on the temperature of the endothermic 9 (heat absorber temperature Te) detected by the heat absorber temperature sensor 48 and the target heat absorber temperature TEO which is the target value thereof. Control the number NC.

(6) Auxiliary heater independent mode The controller 32 of the embodiment stops the compressor 2 and the outdoor blower 15 when over-frost occurs in the outdoor heat exchanger 7, and energizes the auxiliary heater 23. It has an auxiliary heater independent mode that heats the vehicle interior with only the auxiliary heater 23. Also in this case, the controller 32 controls the energization (heat generation) of the auxiliary heater 23 based on the auxiliary heater temperature Tptc detected by the auxiliary heater temperature sensor 50 and the target heater temperature TCO described above.

Further, the controller 32 operates the indoor blower 27, and the air mix damper 28 ventilates the air in the air flow passage 3 blown out from the indoor blower 27 to the auxiliary heater 23 to adjust the air volume. Since the air heated by the auxiliary heater 23 is blown out from the outlet 29 into the vehicle interior, the vehicle interior is heated by this.

(7) Switching of operation mode The air flowing through the air flow passage 3 is cooled by the heat absorber 9 and heated by the radiator 4 (and the auxiliary heater 23) in each of the above operation modes (adjusted by the air mix damper 28). ), And it is blown into the passenger compartment from the outlet 29. The controller 32 is set by the air conditioning operation unit 53 with the outside air temperature Tam detected by the outside air temperature sensor 33, the temperature inside the vehicle body detected by the inside air temperature sensor 37, the blower voltage, the amount of solar radiation detected by the solar radiation sensor 51, and the like. The target outlet temperature TAO is calculated based on the target vehicle interior temperature (set temperature) in the vehicle interior, and the temperature of the air blown from the outlet 29 is controlled to this target outlet temperature TAO by switching each operation mode.

In this case, the controller 32 has the outside air temperature Tam, the humidity in the vehicle interior, the target blowout temperature TAO, the radiator temperature TH, the target radiator temperature TCO, the heat absorber temperature Te, the target heat absorber temperature TEO, and the presence or absence of a dehumidification request in the vehicle interior. Based on the parameters such as, etc., the heating mode, dehumidifying heating mode, dehumidifying cooling mode, cooling mode, MAX cooling mode and auxiliary heater independent mode are accurately switched to realize comfortable and efficient vehicle interior air conditioning.

(8) Back pressure prevention control in dehumidifying and heating mode (1)
Next, the back pressure prevention control executed by the controller 32 in the dehumidifying / heating mode (second operation mode) will be described with reference to FIGS. 4 and 5.

(8-1) Start of reverse pressure prevention control In the dehumidifying / heating mode (second operation mode), the solenoid valve 30 is closed, the outdoor expansion valve 6 (0PLS) is also fully closed, and the refrigerant is inside the radiator 4. It will be in a state of being trapped in etc. Then, since the auxiliary heater 23 is energized and generates heat, the air heated by the auxiliary heater 23 is ventilated to the radiator 4, and the pressure of the refrigerant in the radiator 4, that is, the radiator pressure PCI is changed. It gets higher.

On the other hand, when the load becomes low in such an operating state and the rotation speed NC of the compressor 2 controlled based on the endothermic temperature Te decreases, the discharge pressure Pd of the compressor 2 decreases. Therefore, the pressure on the inlet side (discharge pressure Pd) of the solenoid valve 30 becomes lower than the pressure on the outlet side (radiator pressure PCI), and a back pressure is likely to be applied to the solenoid valve 30.

Therefore, in the embodiment, when the rotation speed NC of the compressor 2 drops below the first predetermined value NC1 (predetermined low value) in this dehumidifying / heating mode, the controller 32 opens the outdoor expansion valve 6 to the predetermined value PLS1. , The back pressure prevention control that also opens the solenoid valve 30 is executed. In this case, the controller 32 sets the timing at which the outdoor expansion valve 6 starts to open and the timing at which the solenoid valve 30 opens at the same time. Further, even if the compressor 2 is turned ON / OFF during that period, the reverse pressure prevention control is continued unless the rotation speed NC becomes equal to or higher than the second predetermined value NC2 described later (FIG. 4).

By opening the outdoor expansion valve 6 and the solenoid valve 30 in this way, a small amount of the refrigerant discharged from the compressor 2 also flows to the radiator 4 side, and the refrigerant flows from the radiator 4 to the outdoor expansion valve 6 to exchange outdoor heat. It will flow into the vessel 7. As a result, the pressure on the inlet side and the outlet side of the solenoid valve 30 is equalized, so that the inconvenience of applying a reverse pressure to the solenoid valve 30 is eliminated. The problem that the durability of the valve 30 is lowered can be solved or suppressed.

In particular, when the controller 32 opens both the outdoor expansion valve 6 and the solenoid valve 30 in the back pressure prevention control as in the embodiment, the pressure on the inlet side and the outlet side of the solenoid valve 30 is quickly equalized, and the pressure is equalized to the solenoid valve 30. It is possible to effectively eliminate the inconvenience of applying pressure. Here, when the outdoor expansion valve 6 and the solenoid valve 30 are opened, if the outdoor expansion valve 6 is opened before the solenoid valve 30, there is a risk that the refrigerant gradually flows through the solenoid valve 30 and a flow noise is generated. However, in the embodiment, the controller 32 opens the outdoor expansion valve 6 and the solenoid valve 30 at the same time when the back pressure prevention control is started, so that such inconvenience can be prevented or suppressed.

(8-2) Completion of Back Pressure Prevention Control After that, if the rotation speed NC of the compressor 2 increases, the discharge pressure Pd also increases, so that the back pressure is less likely to be applied to the solenoid valve 30. Therefore, when the rotation speed NC of the compressor 2 rises to a second predetermined value NC2 or higher, which is higher than the first predetermined value NC1, the controller 32 ends the back pressure prevention control and closes the outdoor expansion valve 6. The solenoid valve 30 is also closed as well as being fully closed. As a result, in the refrigerant circuit R, the outdoor expansion valve 6 is fully closed (0PLS), and the solenoid valve 30 returns to the closed state. That is, it is possible to return to the original operation state of the dehumidifying / heating mode without any trouble when the rotation speed NC of the compressor 2 increases and the back pressure is less likely to be applied to the solenoid valve 30.

(8-3) Prohibition of reverse pressure prevention control On the other hand, the controller 32 constantly monitors the pressure on the inlet side and the outlet side of the solenoid valve 30 in this dehumidifying / heating mode. In this embodiment, the pressure on the inlet side of the electromagnetic valve 30 is determined from the discharge pressure Pd detected and output by the discharge pressure sensor 42 described above, and the pressure on the outlet side of the electromagnetic valve 30 is determined from the pressure sensor 47 described above. Judges from the radiator pressure PCI detected and output by.

Then, in the embodiment, the difference ΔPdx (= Pd-PCI) between the discharge pressure Pd, which is the pressure on the inlet side of the solenoid valve 30, and the radiator pressure PCI, which is the pressure on the outlet side, is equal to or greater than the predetermined maximum error value α. In this case, for example, even if the rotation speed NC of the compressor 2 drops below the first predetermined value NC1 described above, the back pressure prevention control is not executed (prohibited) as shown in FIG. 5, and the outdoor expansion valve 6 is fully closed. Then, the solenoid valve 30 continues to be closed.

Here, the above-mentioned maximum error value α is derived from the detection error (variation) of the discharge pressure sensor 42 and the radiator pressure sensor 47. In this case, it is known in advance that the detection error of the discharge pressure sensor 42 (sensor body and electronic component) is plus or minus e1, and the detection error of the radiator pressure sensor 47 (sensor body and electronic component) is plus or minus e2. If so, the true discharge pressure (referred to as Pdr) is Pd-e1 ≤ Pdr ≤ Pd + e1, and the true radiator pressure (referred to as PCIr) is PCI-e2 ≤ PCIr ≤ PCI + e2.

Therefore, if PCI + e2 ≦ Pd−e1, the pressure on the inlet side and the pressure on the outlet side of the solenoid valve 30 are clearly not reversed. Therefore, in the embodiment, the controller 32 sets the maximum error value α to e1 + e2 (α = e1 + e2), and does not execute the back pressure prevention control when α (= e1 + e2) ≤ difference Pdx (= Pd-PCI). As shown in FIG. 5, when the rotation speed NC is equal to or less than the first predetermined value NC1 and ΔPdx <α, the outdoor expansion valve 6 and the solenoid valve 30 are opened to start the back pressure prevention control. ..

As described above, the discharge pressure Pd output by the discharge pressure sensor 42 is higher than the radiator pressure PCI output by the radiator pressure sensor 47, and the difference ΔPdx (= Pd-PCI) is the discharge pressure sensor 42 and the radiator pressure sensor 47. If the maximum error value α or more derived from the detection errors e1 and e2 of the pressure sensors 42 and e2 is not executed, it is clear even if the detection errors e1 and e2 of the pressure sensors 42 and 47 are taken into consideration. In the operating state where no back pressure is applied to the electromagnetic valve 30, by not performing the back pressure prevention control, unnecessary opening of the outdoor expansion valve 6 and the electromagnetic valve 30 is avoided, and the dehumidifying / heating mode is smoothly continued. You will be able to do it.

(9) Back pressure prevention control (2)
In the above embodiment, both the outdoor expansion valve 6 and the solenoid valve 30 are opened in the back pressure prevention control, but as shown in FIG. 6, the rotation speed NC of the compressor 2 is the first predetermined value NC1. Only the solenoid valve 30 may be opened when the pressure difference between the inlet side and the outlet side of the solenoid valve 30 decreases to the following and the difference ΔPdx is smaller than the maximum error value α. When the solenoid valve 30 is opened, the pressure difference itself between the inlet side and the outlet side disappears, so that the inconvenience of applying a reverse pressure to the solenoid valve 30 can be eliminated or suppressed.

(10) Back pressure prevention control (3)
Further, as shown in FIG. 7, the rotation speed NC of the compressor 2 drops to the first predetermined value NC1 or less, and the pressure difference ΔPdx between the inlet side and the outlet side of the solenoid valve 30 is smaller than the maximum error value α. Occasionally, only the outdoor expansion valve 6 may be opened. If the outdoor expansion valve 6 is opened, the outlet side of the solenoid valve 30 is communicated with the inlet side via the bypass pipe 35-outdoor expansion valve 6-refrigerant pipe 13E-radiator 4, so that the solenoid valve The inconvenience of applying a reverse pressure to 30 can be eliminated or suppressed.

In the reverse pressure prevention control (No. 2) and (No. 3), the back pressure prevention control is terminated and prohibited in the same manner as described above. Further, in each of the above embodiments, the back pressure prevention control of the solenoid valve 30 is executed in the dehumidifying / heating mode, but it may be executed in the MAX cooling mode as the second operation mode. However, in the dehumidifying / heating mode, the radiator 4 is heated by the heat generated by the auxiliary heater 23, so that the internal pressure rises, and the solenoid valve 30 is likely to be subjected to a back pressure in an operating state where the rotation speed NC of the compressor 2 is low. Therefore, the back pressure prevention control is extremely effective.

Further, in the embodiment, the present invention is applied to the vehicle air conditioner 1 that switches and executes each operation mode of the heating mode, the dehumidifying heating mode, the dehumidifying cooling mode, the cooling mode, the MAX cooling mode, and the auxiliary heater independent mode. However, the present invention is not limited to this, and in the invention of claims 1 to 5, at least one of the first operation modes (heating mode, dehumidifying / cooling mode, cooling mode) and the second operation mode (dehumidifying / heating mode, MAX cooling). It is also effective when executing by switching at least one of the modes).

Further, the auxiliary heating device is not limited to the auxiliary heater 23 shown in the embodiment, but is a heat medium circulation circuit that circulates a heat medium heated by the heater to heat the air in the air flow passage, or an engine. A heater core or the like that circulates heated radiator water may be used. Further, the configuration of the refrigerant circuit R described in each of the above embodiments is not limited to that, and it goes without saying that the configuration can be changed without departing from the spirit of the present invention.

1 Vehicle air conditioner 2 Compressor 3 Air flow passage 4 Heat radiator 6 Outdoor expansion valve 7 Outdoor heat exchanger 8 Indoor expansion valve 9 Heat absorber 17 Solenoid valve 21 Solenoid valve 23 Auxiliary heater (auxiliary heating device)
27 Indoor blower (blower fan)
28 Air mix damper 30 Solenoid valve (first solenoid valve)
40 Solenoid valve (second solenoid valve)
32 controller (control device)
35 Bypass piping 42 Discharge pressure sensor 45 Bypass device 47 Dissipator pressure sensor R Refrigerant circuit

Claims (7)

A compressor that compresses the refrigerant and
An air flow passage through which the air supplied to the passenger compartment flows, and
A radiator for radiating the refrigerant and heating the air supplied from the air flow passage to the passenger compartment,
An endothermic absorber for absorbing heat from the refrigerant and cooling the air supplied from the air flow passage to the passenger compartment.
An outdoor heat exchanger installed outside the passenger compartment,
An outdoor expansion valve for reducing the pressure of the refrigerant that exits the radiator and flows into the outdoor heat exchanger.
A first on-off valve provided between the discharge side of the compressor and the inlet side of the radiator, and
A bypass pipe that branches on the upstream side of the first on-off valve, bypasses the radiator and the outdoor expansion valve, and allows the refrigerant discharged from the compressor to flow to the outdoor heat exchanger.
A second on-off valve provided in the bypass pipe and
Equipped with a control device
By opening the first on-off valve and closing the second on-off valve by the control device, the refrigerant discharged from the compressor is allowed to flow through the radiator, and the refrigerant discharged from the radiator is discharged. The first operation mode in which the heat is passed through the outdoor expansion valve to the outdoor heat exchanger,
By fully closing the outdoor expansion valve, closing the first on-off valve, and opening the second on-off valve, the refrigerant discharged from the compressor flows into the outdoor heat exchanger through the bypass pipe. In a vehicle air conditioner that switches and executes a second operation mode in which the refrigerant discharged from the outdoor heat exchanger flows through the heat absorber.
The control device executes back pressure prevention control for opening the outdoor expansion valve and the first on-off valve when the rotation speed of the compressor drops to the first predetermined value or less in the second operation mode. An air conditioner for vehicles characterized by this. The vehicle air conditioner according to claim 1, wherein the control device opens the outdoor expansion valve and the first on-off valve at the same time when the back pressure prevention control is started. A compressor that compresses the refrigerant and
An air flow passage through which the air supplied to the passenger compartment flows, and
A radiator for radiating the refrigerant and heating the air supplied from the air flow passage to the passenger compartment,
An endothermic absorber for absorbing heat from the refrigerant and cooling the air supplied from the air flow passage to the passenger compartment.
An outdoor heat exchanger installed outside the passenger compartment,
An outdoor expansion valve for reducing the pressure of the refrigerant that exits the radiator and flows into the outdoor heat exchanger.
A first on-off valve provided between the discharge side of the compressor and the inlet side of the radiator, and
A bypass pipe that branches on the upstream side of the first on-off valve, bypasses the radiator and the outdoor expansion valve, and allows the refrigerant discharged from the compressor to flow to the outdoor heat exchanger.
A second on-off valve provided in the bypass pipe and
Equipped with a control device
By opening the first on-off valve and closing the second on-off valve by the control device, the refrigerant discharged from the compressor is allowed to flow through the radiator, and the refrigerant discharged from the radiator is discharged. The first operation mode in which the heat is passed through the outdoor expansion valve to the outdoor heat exchanger,
By fully closing the outdoor expansion valve, closing the first on-off valve, and opening the second on-off valve, the refrigerant discharged from the compressor flows into the outdoor heat exchanger through the bypass pipe. In a vehicle air conditioner that switches and executes a second operation mode in which the refrigerant discharged from the outdoor heat exchanger flows through the heat absorber.
The control device opens either the outdoor expansion valve or the first on-off valve when the rotation speed of the compressor drops below the first predetermined value in the second operation mode. An air conditioner for vehicles characterized by performing pressure prevention control. When the control device is executing the back pressure prevention control and the rotation speed of the compressor rises to a second predetermined value higher than the first predetermined value, the back pressure prevention control is performed. The vehicle air conditioner according to any one of claims 1 to 3, wherein the outdoor expansion valve is fully closed and the first on-off valve is returned to the closed state. .. A discharge pressure sensor that detects and outputs the discharge refrigerant pressure of the compressor,
A radiator pressure sensor that detects and outputs the refrigerant pressure of the radiator is provided.
In the second operation mode, the control device has a discharge pressure Pd output by the discharge pressure sensor higher than the radiator pressure PCI output by the radiator pressure sensor, and the difference is the difference between the discharge pressure sensor and the radiator. The vehicle air conditioning according to any one of claims 1 to 4, wherein the reverse pressure prevention control is not executed when the value is equal to or more than the maximum error value derived from the detection error of the pressure sensor. apparatus. An auxiliary heating device for heating the air supplied from the air flow passage to the passenger compartment is provided.
The first operation mode is
A heating mode in which the refrigerant discharged from the compressor is dissipated by the radiator, the dissipated refrigerant is decompressed by the outdoor expansion valve, and then heat is absorbed by the outdoor heat exchanger.
The refrigerant discharged from the compressor is allowed to flow from the radiator to the outdoor heat exchanger to dissipate heat in the radiator and the outdoor heat exchanger, depressurize the radiated refrigerant, and then absorb heat in the heat exchanger. Dehumidifying and cooling mode and
A cooling mode in which the refrigerant discharged from the compressor is flowed from the radiator to the outdoor heat exchanger to dissipate heat in the outdoor heat exchanger, the radiated refrigerant is depressurized, and then heat is absorbed by the heat exchanger. Any of them, or a combination of them, or all of them.
The second operation mode is
The refrigerant discharged from the compressor is allowed to flow from the bypass pipe to the outdoor heat exchanger to dissipate heat, and after depressurizing the radiated refrigerant, the heat absorber absorbs heat and dehumidifies the auxiliary heating device. Heating mode and
One of the maximum cooling modes in which the refrigerant discharged from the compressor is allowed to flow from the bypass pipe to the outdoor heat exchanger to dissipate heat, the radiated refrigerant is depressurized, and then heat is absorbed by the heat absorber, or The vehicle air conditioner according to any one of claims 1 to 5, wherein the air conditioner is all of them. The auxiliary heating device is provided on the upstream side of the radiator with respect to the air flow in the air flow passage, and is also provided.
The vehicle air conditioner according to claim 6, wherein the second operation mode is the dehumidification / heating mode.

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