Vehicle air conditioning

Abstract

Vehicle air conditioning system (1) with: a compressor (2) that compresses a coolant; an airflow channel (3) through which air flows to supply a vehicle interior; a radiator (4) which is arranged in the airflow duct (3) to cause the coolant to radiate heat; a heat absorber (9) arranged in the airflow channel (3) to cause the coolant to absorb heat; an external heat exchanger (7) located outside the vehicle interior to cause the coolant to radiate or absorb heat; and a control device (32), wherein the control device (32) is configured to modify and execute at least one of the following: a heating mode in which the coolant released from the compressor (2) radiates heat in the radiator (4), and the coolant from which heat is radiated is expanded and then absorbs heat in the external heat exchanger (7); a dehumidification and heating mode in which the refrigerant released from the compressor (2) radiates heat in the radiator (4), and the refrigerant from which the heat was radiated is expanded and then absorbs heat only in the heat absorber (9) or in the heat absorber (9) and the external heat exchanger (7); a dehumidification and cooling mode in which the refrigerant discharged by the compressor (2) radiates heat into the radiator (4) and the external heat exchanger (7), and the refrigerant from which the heat was radiated is expanded and then absorbs heat in the heat absorber (9); and a cooling mode in which the refrigerant discharged from the compressor (2) radiates heat in the external heat exchanger (7), and the refrigerant from which the heat was radiated is expanded and then absorbs heat in the heat absorber (9), wherein the control device (32) is configured to switch to the dehumidification and cooling mode based on a situation in which a difference (Te - TEO) of a heat absorber temperature (Te) and a heat absorber setpoint temperature (TEO) is greater than a predetermined value or a difference (TH - TCO) of a radiator temperature (TH) and a radiator setpoint temperature (TCO) is a predetermined value or more in the dehumidification and heating mode, and wherein the control device (32) is also configured to switch to the dehumidification and heating mode on the basis of a situation in which a difference (TCO - TH) between the radiator setpoint temperature (TCO) and the radiator temperature (TH) is greater than a predetermined value in the dehumidification and cooling mode.

Description

TECHNICAL FIELD

[0001] The present invention relates to a heat pump system air conditioner that conditions the air in a vehicle interior, and more particularly, it relates to an air conditioner suitable for a hybrid vehicle or an electric vehicle. STATE OF THE ART

[0002] Due to current environmental problems in recent years, hybrid vehicles and electric vehicles have become common. Furthermore, as an air conditioner suitable for such a vehicle, an air conditioner has been developed that includes a compressor for compressing and discharging a refrigerant, a heater disposed on a vehicle interior for causing the refrigerant to radiate heat, a heat absorber disposed on the vehicle interior for causing the refrigerant to absorb heat, and an outdoor heat exchanger disposed outside the vehicle interior for causing the refrigerant to radiate or absorb heat. It also includes a heating operation in which the refrigerant discharged from the compressor radiates heat in the heater, and the refrigerant, by which heat has been radiated in this refrigerant, absorbs heat in the outdoor heat exchanger, and a dehumidifying and heating operation.in which the coolant discharged from the compressor radiates heat into the radiator, and the coolant through which heat was radiated in the radiator absorbs heat only in the heat absorber or in this heat absorber and the outdoor heat exchanger, a cooling operation in which the coolant discharged from the compressor radiates heat into the outdoor heat exchanger and absorbs heat into the heat absorber, and a dehumidification and cooling operation in which the coolant discharged from the compressor radiates heat into the radiator and the outdoor heat exchanger and absorbs heat into the heat absorber (see, for example, Patent Document 1). LIST OF CITIONS Patent Publications

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. JP 2012 176659 A

[0004] Further vehicle air conditioning systems are known from DE 10 2010 046 030 A1 and DE 11 2012 000 758 T5. SUMMARY OF THE INVENTION Problems to be solved by the invention:

[0005] In the above-described conventional vehicle air conditioner, a mode of the above-described heating operation, dehumidifying and heating operation, cooling operation, and dehumidifying and cooling operation is selected and changed according to a combination of an outside air temperature Tam and a target outlet temperature TAO (a target value of a temperature of air blown out into a vehicle interior).

[0006] Here, an optimal operating mode for the air conditioner exists under conditions such as a vehicle's environment and a set temperature. However, such conventional mode change control has the problem that the optimal operating mode is not necessarily selected. Furthermore, if an inappropriate operating mode is selected, a desired air conditioning function cannot be performed, and comfortable air conditioning cannot be realized in the vehicle interior.

[0007] The present invention has been created to solve these conventional technical problems, and its object is to provide a vehicle air conditioner that can select and change an optimal operation mode so that a desired air conditioning function can be performed under conditions such as an environment and a set temperature. Means to solve the problems

[0008] A vehicle air conditioner of the present invention according to claim 1 has a compressor that compresses a refrigerant, an air flow passage through which air to be supplied to a vehicle interior flows, a heater core arranged in this air flow passage for causing the refrigerant to radiate heat, a heat absorber arranged in the air flow passage for causing the refrigerant to absorb heat, an outdoor heat exchanger arranged outside the vehicle interior for causing the refrigerant to radiate or absorb heat, and a control device, this control device being configured to select at least a heating mode in which the refrigerant discharged from the compressor radiates heat into the heater core and the refrigerant through which heat has been radiated is expanded and then absorbs heat into the outdoor heat exchanger, a dehumidifying and heating mode,in which the refrigerant discharged from the compressor radiates heat into the radiator and the refrigerant through which heat has been radiated expands and then absorbs heat only into the heat absorber or into the heat absorber and the outdoor heat exchanger, a dehumidification and cooling mode in which the refrigerant discharged from the compressor radiates heat into the radiator and the outdoor heat exchanger and the refrigerant through which heat has been radiated expands and then absorbs heat into the heat absorber, or a cooling mode in which the refrigerant discharged from the compressor radiates heat into the outdoor heat exchanger and the refrigerant through which heat has been radiated expands and then absorbs heat into the heat absorber.

[0009] The vehicle air conditioning system according to the invention is further characterized in that the control device switches to the dehumidifying and cooling mode based on a situation in which the heat absorption in the heat absorber becomes low or the heat radiation in the heater core becomes excessive in the dehumidifying and heating mode, and also switches to the dehumidifying and heating mode based on a situation in which the heat radiation in the heater core becomes low in this dehumidifying and cooling mode.

[0010] In particular, it is provided that the control device is designed to switch to the dehumidification and cooling mode based on a situation in which a difference (Te - TEO) of a heat absorber temperature (Te) and a heat absorber target temperature (TEO) is greater than a predetermined value or a difference (TH - TCO) of a radiator temperature (TH) and a radiator target temperature (TCO) is a predetermined value or more in the dehumidification and heating mode, and that the control device is further designed to switch to the dehumidification and heating mode based on a situation in which a difference (TCO - TH) of the radiator target temperature (TCO) and the radiator temperature (TH) is greater than a predetermined value in the dehumidification and cooling mode.

[0011] The vehicle air conditioner of the invention according to claim 2 is characterized in that, in the invention described above, the control device has an internal cycle mode in which the refrigerant is prohibited from flowing into the outdoor heat exchanger, and the refrigerant absorbs heat only in the heat absorber, in the dehumidifying and heating mode, it switches to the internal cycle mode based on a situation where the heat absorption in the heat absorber becomes low or the heat radiation in the heater core becomes excessive in the dehumidifying and heating mode, and further switches to the dehumidifying and cooling mode based on a situation where the heat absorption in the heat absorber becomes further low or the heat radiation in the heater core becomes further excessive in this internal cycle mode.

[0012] The vehicle air conditioner of the invention according to claim 3 is characterized in that, in the invention described above, the control means switches to the internal cycle mode based on the situation where the heat radiation into the heater core becomes small in the dehumidifying and cooling mode, and further switches to the dehumidifying and heating mode based on the situation where the heat radiation into the heater core becomes small or the heat absorption into the heat absorber becomes excessive in this internal cycle mode.

[0013] The vehicle air conditioner of the invention according to claim 4 is characterized in that in the respective inventions described above, the control means switches from the heating mode to the dehumidifying and heating mode or the dehumidifying and cooling mode based on a situation where an outside air temperature and an outside air humidity increase, and switches from the dehumidifying and heating mode and the dehumidifying and cooling mode to the heating mode based on a situation where the outside air temperature and the outside air humidity decrease.

[0014] The vehicle air conditioner of the invention according to claim 5 is characterized in that, in the invention described above, the control means switches from the heating mode to the dehumidifying and cooling mode based on a situation where the outside air temperature rises to a temperature higher than a temperature of a condition for switching from the heating mode to the dehumidifying and heating mode.

[0015] The vehicle air conditioner of the invention according to claim 6 has an expansion valve that expands the refrigerant flowing into the outdoor heat exchanger in the respective inventions described above, and is characterized in that the control means switches from the dehumidifying and cooling mode to the cooling mode based on a situation where a valve position of the expansion valve reaches an upper limit of control, and switches from the cooling mode to the dehumidifying and cooling mode based on the situation where heat radiation into the radiator becomes small.

[0016] The vehicle air conditioner of the invention according to claim 7 in the respective inventions described above has a suction change damper that changes an outside air introduction mode for introducing the outside air into the air flow passage and an inside air circulation mode for introducing the air in the vehicle interior into the air flow passage, and is characterized in that, when the control device executes the heating mode or the dehumidifying and heating mode at startup, the control device changes the suction change damper to the outside air introduction mode in a case where at least the outside air temperature is higher than an inside temperature or at least an inside humidity is higher than the outside air humidity, and changes it to the inside air circulation mode in a case where at least the inside temperature is higher than the outside air temperature or at least the outside air humidity is higher than the inside humidity.

[0017] The vehicle air conditioner of the invention according to claim 8 in the respective inventions described above has a suction change damper that changes an outside air introduction mode for introducing the outside air into the air flow passage and an inside air circulation mode for introducing the air in the vehicle interior into the air flow passage, and is characterized in that, when the control device executes the cooling mode or the dehumidifying and cooling mode at startup, the control device changes the suction change damper to the inside air circulation mode in a case where at least the outside air temperature is higher than the inside temperature or at least the outside air humidity is higher than the inside humidity, and changes it to the outside air introduction mode in a case where at least the inside temperature is higher than the outside air temperature or at least the inside humidity is higher than the outside air humidity.

[0018] The vehicle air conditioner of the invention according to claim 9 is characterized in that in the invention according to claim 7 or claim 8, in a stable state after start-up, the control means switches the suction change damper to the outside air introduction mode in a case where a carbon dioxide concentration in the vehicle interior is high, or the inside air circulation mode continues for a predetermined time or more, or the inside humidity is higher than the outside air humidity, or a set value of the temperature of the air blown into the vehicle interior is equal to or close to the outside air temperature, and the control means switches the suction change damper to the inside air circulation mode under conditions different from the above-described conditions. Advantageous effect of the invention

[0019] According to the present invention, a vehicle air conditioner includes a compressor that compresses a refrigerant, an air flow passage through which air flows to be supplied to a vehicle interior, a heater disposed in this air flow passage to cause the refrigerant to radiate heat, a heat absorber disposed in the air flow passage to cause the refrigerant to absorb heat, an exterior heat exchanger disposed outside the vehicle interior to cause the refrigerant to radiate or absorb heat, and the control device. This control device is configured to perform at least one heating mode in which the refrigerant discharged from the compressor radiates heat into the heater, and the refrigerant through which heat has been radiated is expanded and then absorbs heat into the exterior heat exchanger, a dehumidification and heating mode,in which the coolant discharged from the compressor radiates heat into the radiator, and the coolant through which heat has been radiated expands and then absorbs heat only into the heat absorber or into the heat absorber and the outdoor heat exchanger, a dehumidification and cooling mode in which the coolant discharged from the compressor radiates heat into the radiator and the outdoor heat exchanger, and the coolant through which heat has been radiated expands and then absorbs heat into the heat absorber, or a cooling mode in which the coolant discharged from the compressor radiates heat into the outdoor heat exchanger, and the coolant through which heat has been radiated expands and then absorbs heat into the heat absorber. In the vehicle air conditioning system, the control device switches to the dehumidification and cooling mode based on a situation,in which heat radiation in the heat absorber becomes low or heat radiation into the heater core becomes excessive in the dehumidification and heating mode, and it also switches to the dehumidification and heating mode based on a situation in which heat radiation into the heater core becomes low in this dehumidification and cooling mode. Therefore, it is possible to precisely change an operation mode between the dehumidification and heating mode and the dehumidification and cooling mode according to the situation in which heat radiation in the heater core or heat absorption into the heat absorber becomes low or excessive, under conditions such as a vehicle environment and a set temperature.

[0020] According to the invention of claim 2, in addition to the invention described above, when the control device has an internal cycle mode in the dehumidifying and heating mode in which the refrigerant is prohibited from flowing into the outdoor heat exchanger and the refrigerant absorbs heat only into the heat absorber, the control device switches to the internal cycle mode based on a situation in which the heat absorption in the heat absorber becomes low or the heat radiation into the radiator becomes excessive in the dehumidifying and heating mode, and also switches to the dehumidifying and cooling mode based on a situation in which the heat absorption into the heat absorber becomes further low or the heat radiation into the radiator becomes further excessive in this internal cycle mode.Therefore, it is possible to accurately change the operation mode from the dehumidifying and heating mode to the internal cycle mode and further from the internal cycle mode to the dehumidifying and cooling mode according to the situation of heat absorption in the heat absorber or heat radiation in the radiator.

[0021] According to the invention of claim 3, in addition to the above-described invention, the control device switches to the internal cycle mode based on the situation where heat radiation into the radiator becomes low in the dehumidifying and cooling mode, and further switches to the dehumidifying and heating mode based on the situation where heat radiation into the radiator becomes low or heat absorption into the heat absorber becomes excessive in this internal cycle mode. Therefore, it is possible to precisely change the operation mode from the dehumidifying and cooling mode to the internal cycle mode, and further from the internal cycle mode to the dehumidifying and heating mode according to the situation of heat radiation into the radiator or heat absorption into the heat absorber.

[0022] According to the invention of claim 4, in addition to the respective inventions described above, the control device switches from the heating mode to the dehumidifying and heating mode or the dehumidifying and cooling mode based on a situation where an outside air temperature and outside air humidity increase, and switches from the dehumidifying and heating mode and the dehumidifying and cooling mode to the heating mode based on a situation where the outside air temperature and outside air humidity decrease. Therefore, it is possible to accurately change the operation mode among the heating mode, the dehumidifying and heating mode, and the dehumidifying and cooling mode according to an outside air environment.

[0023] According to the invention of claim 5, in addition to the above-described invention, the control device switches from the heating mode to the dehumidifying and cooling mode based on a situation where the outside air temperature rises to a temperature higher than a temperature of a condition for switching from the heating mode to the dehumidifying and heating mode. Therefore, it is possible to switch directly from the heating mode to the dehumidifying and cooling mode in a situation where the outside air temperature continues to rise.

[0024] According to the invention of claim 6, in addition to the respective inventions described above, the vehicle air conditioner has an expansion valve that expands the refrigerant flowing into the outdoor heat exchanger, and the control device switches from the dehumidifying and cooling mode to the cooling mode based on a situation where a valve position of the expansion valve reaches an upper limit of control, and switches from the cooling mode to the dehumidifying and cooling mode based on a situation where heat radiation into the radiator becomes low. Therefore, it is possible to accurately change the operation mode between the cooling mode and the dehumidifying and cooling mode according to a control situation of the expansion valve or the heat radiation situation of the radiator.

[0025] According to the invention of claim 7, in addition to the respective inventions described above, the vehicle air conditioner additionally has a suction change damper that changes an outside air introduction mode for introducing the outside air into the air flow passage and an inside air circulation mode for introducing the air in the vehicle interior into the air flow passage, and is characterized in that, when the control device executes the heating mode or the dehumidifying and heating mode at startup, the control device changes the suction change damper to the outside air introduction mode in a case where at least the outside air temperature is higher than an inside temperature or at least an inside humidity is higher than the outside air humidity, and to the inside air circulation mode in a case where at least the inside temperature is higher than the outside air temperature or at least the outside air humidity is higher than the inside humidity.Therefore, when the heating mode or the dehumidification and heating mode is executed at startup, it is possible to accurately change the outside air introduction mode and the inside air circulation mode according to the outside air environment and effectively utilize the heat in the outside air to heat the vehicle.

[0026] According to the invention of claim 8, in addition to the respective inventions described above, the vehicle air conditioner further includes a suction change damper that changes an outside air introduction mode for introducing the outside air into the air flow duct and an inside air circulation mode for introducing the air in the vehicle interior into the air flow duct. When the controller executes the cooling mode or the dehumidifying and cooling mode at startup, the controller changes the suction change damper to the inside air circulation mode in a case where at least the outside air temperature is higher than an inside temperature or at least the outside air humidity is higher than an inside humidity, and to the outside air introduction mode in a case where at least the inside temperature is higher than the outside air temperature or at least the inside humidity is higher than the outside air humidity.Therefore, when the cooling mode or the dehumidification and cooling mode is executed at startup, the outside air introduction mode and the inside air circulation mode are accurately changed according to the outside air environment, so that it is possible to eliminate a bad influence of the heat in the outside air on cooling the vehicle or to effectively utilize the cold in the outside air to cool the vehicle.

[0027] In this case, as in the invention according to claim 9, the control device switches the suction change damper to the outside air introduction mode in the stable state after starting in a case where a carbon dioxide concentration in the vehicle interior is high, or the inside air circulation mode continues for a predetermined time or more, or the inside humidity is higher than the outside air humidity, or a target value of a temperature of the air blown into the vehicle interior is equal to or close to the outside air temperature, and the control device switches the suction change damper to the inside air circulation mode under conditions different from the above-described conditions. Therefore, it is possible to accurately change the outside air introduction mode and the inside air circulation mode also according to the carbon dioxide concentration in the vehicle interior or a target exit temperature in the stable state.

[0028] As described above, according to the vehicle air conditioner of the present invention, it is possible to select and change an optimal operation mode so that a desired air conditioning function can be performed under conditions such as an environment of the vehicle or a set temperature, and the desired air conditioning function is performed so that comfortable air conditioning in the vehicle can be realized. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a configuration view of a vehicle air conditioner of an embodiment to which the present invention is applied; Fig. 2 shows a block diagram of an electrical circuit of a control device of the vehicle air conditioning system of Fig. 1; Fig. 3 shows a control block diagram relating to a compressor control of the control device of the Fig. 2; Fig. Figure 4 shows another control block diagram relating to the compressor control of the control device of the Fig. 2; Fig. 5 shows a control block diagram relating to an outdoor expansion valve control of the control device of the Fig. 2; Fig. Fig. 6 is a diagram for explaining an operation mode when starting the control device of the Fig. 2; Fig. Fig. 7 is a diagram for explaining a change control of the operation mode by the control device of the Fig. 2; Fig. Fig. 8 is a diagram for explaining another example of the change control of the operation mode by the control device of the Fig. 2; Fig. Fig. 9 is a diagram for explaining a control of a suction change damper by the control device of the Fig. 2; Fig. Fig. 10 is a diagram for explaining the change control of a normal mode and a radiator temperature priority mode in a dehumidifying and cooling mode by the control device of the Fig. 2; Fig. 11 shows a control block diagram of the control device in the radiator temperature priority mode of the Fig. 10; Fig. Fig. 12 shows a time chart of the change control of the normal mode and the radiator temperature priority mode in the dehumidification and cooling mode of the Fig. 10; Fig. Fig. 13 is a diagram for explaining another example of the change control of the normal mode and the radiator temperature priority mode in the dehumidifying and cooling mode by the control device of the Fig. 2; Fig. 14 shows a flowchart for explaining the change control of the Fig. 13; Fig. 15 shows a control block diagram of the control device in the radiator temperature priority mode of the Fig. 13; Fig. Fig. 16 is a diagram for explaining another example of the change control of the normal mode and the radiator temperature priority mode in the dehumidifying and cooling mode by the control device of the Fig. 2; Fig. 17 shows a flowchart for explaining the change control of the Fig. 16; Fig. Fig. 18 shows a control block diagram of the control device in the radiator temperature priority mode of the Fig. 16; Fig. Fig. 19 is a diagram for explaining another example of the change control of the normal mode and the radiator temperature priority mode in the dehumidifying and cooling mode by the control device of the Fig. 2; Fig. 20 shows a flowchart for explaining the change control of the Fig. 19; Fig. Fig. 21 is a flowchart for explaining another example of change control of the Fig. 19; and Fig. Fig. 22 shows a control block diagram of the control device in the radiator temperature priority mode of the Fig. 21. MODE FOR CARRYING OUT THE INVENTION

[0029] An embodiment of the present invention will be described in detail below with reference to the drawings.

[0030] The Fig. 1 shows a configuration view of a vehicle air conditioner 1 of an embodiment of the present invention. In this case, a vehicle of the embodiment to which the present invention is applied is an electric vehicle (EV) that has no engine (no internal combustion engine), and it travels by driving an electric motor to travel by power charged in a battery (not shown). The vehicle air conditioner 1 of the present invention is driven by the power of the battery.

[0031] Namely, in the electric vehicle in which heating is not effected by waste heat of the engine, the vehicle air conditioner 1 of the embodiment performs heating by a heat pump operation using a refrigerant cycle, and further selectively performs respective operation modes of dehumidifying and heating, cooling and dehumidifying, cooling, and the like. Note that the vehicle is not limited to the electric vehicle, and the present invention is also effective for a so-called hybrid vehicle in which the engine is used together with the electric motor for traveling, and further applicable to an ordinary vehicle traveling by the engine.

[0032] The vehicle air conditioner 1 of the embodiment performs air conditioning (heating, cooling, dehumidification, and ventilation) in the electric vehicle. An electric compressor 2 that compresses a refrigerant to increase pressure; a heater core 4 disposed on an air flow passage 3 of an HVAC unit 10 through which the air in the vehicle interior passes and circulates so that the high-temperature and high-pressure refrigerant discharged from the compressor 2 radiates heat into the vehicle interior; an outdoor expansion valve 6 formed of an electric valve that relaxes and expands the refrigerant during heating; an outdoor heat exchanger 7 that performs heat exchange between the refrigerant and the outside air, thus serving as a heater core during cooling and as an evaporator during heating; and an indoor expansion valve 8.which is formed of an electric valve that relaxes and expands the coolant, a heat absorber 9 arranged in the air flow channel 3 to cause the coolant to absorb heat from the interior and exterior of the vehicle during cooling and during dehumidification and heating, an evaporation capability control valve 11 that regulates evaporation capability in the heat absorber 9, an accumulator 12, and the like, so that a coolant circuit R is formed. Note that an outdoor fan 15 is arranged in the outdoor heat exchanger 7 to perform heat exchange between the outside air and the coolant when the vehicle is stopped.

[0033] In addition, the outdoor heat exchanger 7 has a header portion 14 and a subcooling portion 16 sequentially on a downstream coolant side. A coolant pipe 13A extending from the outdoor heat exchanger 7 is connected to the header portion 14 via a solenoid valve (an opening / closing valve) 17 that is opened during cooling. An outlet of the subcooling portion 16 is connected to the indoor expansion valve 8 via a check valve 18. Note that the header portion 14 and the subcooling portion 16 structurally constitute a part of the outdoor heat exchanger 7, and a side of the indoor expansion valve 8 of the check valve 18 is a forward direction.

[0034] In addition, a refrigerant pipe 13B is arranged between the check valve 18 and the indoor expansion valve 8 in a heat exchange relationship with a refrigerant pipe 13C extending from the evaporability control valve 11 positioned on an outlet side of the heat absorber 9, and both pipes form an indoor heat exchanger 19. Consequently, the refrigerant flowing into the indoor expansion valve 8 through the refrigerant pipe 13B is cooled (subcooled) by the low-temperature refrigerant flowing out of the heat absorber 9 through the evaporability control valve 11.

[0035] In addition, the coolant pipe 13A extending from the outdoor heat exchanger 7 is branched, and this branched coolant pipe 13D is connected to the coolant pipe 13C on the downstream side of the indoor heat exchanger 19 through a solenoid valve (an opening / closing valve) 21 that is opened during heating. Furthermore, a coolant pipe 13E is branched on an outlet side of the radiator 4 before the outdoor expansion valve 6, and this branched coolant pipe 13F is connected to the coolant pipe 13B on the downstream side of the check valve 18 through a solenoid valve (an opening / closing valve) 22 that is opened during dehumidification.

[0036] In addition, a refrigerant pipe 13G is branched on an outlet side of the compressor 2, and this branched refrigerant pipe 13H is connected to a refrigerant pipe 13I between the outdoor expansion valve 6 and the outdoor heat exchanger 7 through a solenoid valve (an opening / closing valve) 23, which is opened during defrosting of the outdoor heat exchanger 7 to allow the high-temperature refrigerant (a hot gas) discharged from the compressor 2 to flow directly into the outdoor heat exchanger 7 and a check valve 24. Note that a direction of the refrigerant pipe 13I of the check valve 24 is the forward direction.

[0037] In addition, in the air flow channel 3 on an upstream air side of the heat absorber 9, corresponding suction connections (through a suction connection 25 in the Fig. 1), such as an inside air suction port and an outside air suction port, and a suction change damper 26 is arranged in the suction port 25 to change the air introduced into the air flow duct 3 into inside air, which is the air inside the vehicle interior (an inside air circulation mode), and outside air, which is air outside the vehicle interior (an outside air introduction mode). Furthermore, an inside blower (a fan blower) 27 is arranged on an airstream side of the suction change damper 26 to supply the introduced inside air or outside air to the air flow duct 3.

[0038] In addition, an air mixing damper 28 is arranged in the air flow duct 3 on the air upstream side of the heater core 4 in order to regulate a flow rate of the inside air or the outside air through the heater core 4. Furthermore, an outlet for the footwell, ventilation or defrosting (through an outlet 29 in the Fig. 1), and an output change damper 31 is arranged in the output 29 to perform change control for blowing the air out of the corresponding output described above.

[0039] Next, the Fig. 2, a control device (ECU) 32 as a control means constituted by a microcomputer, and an input of the control device 32 is connected to respective outputs of an outside air temperature sensor 33 that detects an outside air temperature of the vehicle, an outside air humidity sensor 34 that detects an outside air humidity, an HVAC suction temperature sensor 36 that detects a suction temperature from the suction port 25 to the air flow duct 3, an inside air temperature sensor 37 that detects a temperature of the air in the vehicle interior (the inside air), an inside air humidity sensor 38 that detects a humidity of the air in the vehicle interior, an inside air CO2 concentration sensor 39 that detects a carbon dioxide concentration in the vehicle interior, an outlet temperature sensor 41 that detects a temperature of the air blown into the vehicle interior from the outlet 29, and an outlet pressure sensor 42.which detects a pressure of the coolant discharged from the compressor 2, an outlet temperature sensor 43 which detects a temperature of the coolant discharged from the compressor 2, a suction pressure sensor 44 which detects a suction coolant pressure of the compressor 2, a radiator temperature sensor 46 which detects a temperature of the radiator 4 (the temperature of the radiator 4 itself or the temperature of the air heated in the radiator 4), a radiator pressure sensor 47 which detects a coolant pressure of the radiator 4 (the pressure in the radiator 4 or the pressure of the coolant flowing out of the radiator 4), a heat absorber temperature sensor 48 which detects a temperature of the heat absorber 9 (the temperature of the heat absorber 9 itself or the air cooled in the heat absorber 9), a heat absorber pressure sensor 49,which detects a coolant pressure of the heat absorber 9 (the pressure in the heat absorber 9 or the pressure of the coolant flowing out of the heat absorber 9), a solar ray sensor 51 such as a photosensor system for detecting an amount of solar ray in the vehicle, a speed sensor 52 for detecting a moving speed of the vehicle (a speed), an operating section 53 for adjusting the change in temperature or the operation mode, an outdoor heat exchanger temperature sensor 54 that detects a temperature of the outdoor heat exchanger 7, and an outdoor heat exchanger pressure sensor 56 that detects the coolant pressure of the outdoor heat exchanger 7.

[0040] An output of the control device 32 is connected to the compressor 2, the outdoor fan 15, the indoor fan (fan blower) 27, the suction change damper 26, the air mixing damper 28, the output change damper 31, the outdoor expansion valve 6, the indoor expansion valve 8, the respective solenoid valves 23, 22, 17, and 21, and the evaporation capability control valve 11. In addition, the output of the control device 32 is also connected to an electric heater 57 arranged in the air flow channel 3 on the downstream side of the heater core 4 to supplement the heating by the heater core 4. The control device 32 controls these components based on the outputs from the respective sensors and the setting inputs from the operating section 53.

[0041] Next, an operation of the vehicle air conditioner 1 of the embodiment having the above-described structure will be described. In the embodiment, the control device 32 changes and executes roughly classified operation modes, such as a heating mode, a dehumidifying and heating mode, an internal cycle mode, a dehumidifying and cooling mode, and a cooling mode. First, the flow of the refrigerant in each operation mode will be described. (1) Heating mode

[0042] When the heating mode is selected by the control device 32 or by a manual operation by the operation section 53, the control device 32 opens the solenoid valve 21 and closes the solenoid valve 17, the solenoid valve 22, and the solenoid valve 23. In addition, the compressor 2 and the respective fans 15 and 27 are operated, and the air mixing damper 28 has a state where the air blown out from the indoor fan 27 passes through the heater core 4. Consequently, the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the radiator 4. The air in the air flow channel 3 passes through the radiator 4, and thus the air in the air flow channel 3 is heated by the high-temperature refrigerant in the radiator 4, whereas the refrigerant in the radiator 4 has the heat absorbed by the air and is cooled, so it condenses and liquefies.

[0043] The refrigerant liquefied in the radiator 4 flows through the refrigerant pipe 13E to reach the outdoor expansion valve 6, which expands the refrigerant, and then the refrigerant flows into the outdoor heat exchanger 7. The refrigerant flowing into the outdoor heat exchanger 7 evaporates, and the heat is pumped from the outside air passing through it or by the outdoor fan 15 (a heat pump). Furthermore, the low-temperature refrigerant flowing out of the outdoor heat exchanger 7 flows through the refrigerant pipe 13D and the solenoid valve 21, so that it flows from the refrigerant pipe 13C into the accumulator 12, where gas-liquid separation is effected. Then, the gas refrigerant is sucked into the compressor, thereby repeating this circulation. The air heated in the heater core 4 is blown out of the outlet 29, thus heating the vehicle interior.

[0044] The control device 32 controls a rotation speed of the compressor 2 based on a high pressure of the refrigerant circuit R detected by the outlet pressure sensor 42 or the radiator pressure sensor 47, and also controls a valve position of the outdoor expansion valve 6 based on the temperature of the radiator 4 detected by the radiator temperature sensor 46 and the refrigerant pressure of the radiator 4 detected by the radiator pressure sensor 47, and controls a subcooling degree of the refrigerant in the outlet of the radiator 4. (2) Dehumidification and heating mode

[0045] Next, in the dehumidification and heating mode, the control device 32 opens the solenoid valve 22 in the above-described heating mode state. Consequently, a portion of the condensed refrigerant flowing through the radiator 4 and the refrigerant pipe 13E is dispersed and flows through the solenoid valve 22, flowing out of the refrigerant pipes 13F and 13B through the indoor heat exchanger 19, thereby reaching the indoor expansion valve 8. The refrigerant is expanded in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. Water in the air blown out from the indoor fan 27 coagulates to adhere to the heat absorber 9 through a heat absorption operation at this time, and thus the air is cooled and dehumidified.

[0046] The refrigerant evaporated in the heat absorber 9 flows through the evaporation capacity control valve 11 and the interior heat exchanger 19 to mix with the refrigerant from the refrigerant pipe 13D in the refrigerant pipe 13C, and then flows through the accumulator 12 to be drawn into the compressor 2, thereby repeating this circulation. The air dehumidified in the heat absorber 9 is reheated in a process of passing through the heater core 4, thus effecting dehumidification and heating in the vehicle interior.

[0047] The control device 32 controls the rotation speed of the compressor 2 based on the high pressure of the refrigerant circuit R detected by the outlet pressure sensor 42 or the radiator pressure sensor 47, and also controls the valve position of the outdoor expansion valve 6 based on the temperature of the heat absorber 9 detected by the heat absorber temperature sensor 48. (3) Internal cycle mode

[0048] Next, in the internal cycle mode, the control device 32 closes (interrupts) the outdoor expansion valve 6 in the above-described dehumidification and heating mode. Namely, it can be assumed that this internal cycle mode is a state in which the outdoor expansion valve 6 is interrupted by controlling the outdoor expansion valve 6 in the dehumidification and heating mode, and thus, the internal cycle mode can be considered as part of the dehumidification and heating mode.

[0049] However, when the outdoor expansion valve 6 is closed, the refrigerant is prohibited from flowing into the outdoor heat exchanger 7, and thus all the condensed refrigerant flowing through the radiator 4 and the refrigerant pipe 13E flows through the solenoid valve 22 to the refrigerant pipe 13F. Moreover, the refrigerant flowing through the refrigerant pipe 13F flows from the refrigerant pipe 13B through the indoor heat exchanger 19 to reach the indoor expansion valve 8. The refrigerant is expanded in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. The water in the air blown out from the indoor fan 27 coagulates, adhering to the heat absorber 9 through the heat absorption operation at this time, and thus the air is cooled and dehumidified.

[0050] The refrigerant evaporated in the heat absorber 9 flows through the evaporation control valve 11, the indoor heat exchanger 19, the refrigerant pipe 13C, and the accumulator 12, so that it is sucked into the compressor 2, thereby repeating this circulation. The air dehumidified in the heat absorber 9 is reheated in a process of passing through the heater core 4, thus achieving dehumidification and heating in the vehicle interior. However, in this internal cycle mode, the refrigerant circulates between the heater core 4 (heat heating) and the heat absorber 9 (heat absorption), which are provided in the air flow passage 3 on an inside side, and thus, heat is not pumped out from the outside air, but a heating function for consumed power of the compressor 2 is performed.The entire amount of the refrigerant flows through the heat absorber 9, which performs a dehumidifying operation, and thus the dehumidifying ability is high compared with the dehumidifying and heating mode described above, but the heating ability is lower.

[0051] The control device 32 controls the rotational speed of the compressor 2 based on the temperature of the heat absorber 9 or the above-described high pressure of the refrigerant circuit R. At this time, the control device 32 selects a smaller compressor target rotational speed from compressor target rotational speeds obtained by calculations from the temperature of the heat absorber 9 or the high pressure to control the compressor 2 as described later. (4) Dehumidification and cooling mode

[0052] Next, in the dehumidification and cooling mode, the control device 32 opens the solenoid valve 17 and closes the solenoid valve 21, the solenoid valve 22, and the solenoid valve 23. Furthermore, the compressor 2 and the respective fans 15 and 27 are operated, and the air mixing damper 28 is in a state where the air blown out from the indoor fan 27 passes through the radiator 4. Consequently, the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the radiator 4. The air in the air flow channel 3 passes through the radiator 4, and thus the air in the air flow channel 3 is heated by the high-temperature refrigerant in the radiator 4, whereas the refrigerant in the radiator 4 has the heat extracted from the air and is cooled to condense and liquefy.

[0053] The coolant flowing out of the radiator 4 flows through the coolant pipe 13E to reach the outdoor expansion valve 6, and flows through the outdoor expansion valve 6, which is controlled so that the valve tends to open, so that the coolant flows into the outdoor heat exchanger 7. The coolant flowing into the outdoor heat exchanger 7 is cooled by passing therethrough or by the outside air passing through the outdoor fan 15 to condense. The coolant flowing out of the outdoor heat exchanger 7 flows out of the coolant pipe 13A through the solenoid valve 17 to then flow into the header section 14 and the subcooling section 16. At this time, the coolant is subcooled.

[0054] The refrigerant flowing out of the subcooling section 16 of the outdoor heat exchanger 7 flows through the check valve 18 to enter the refrigerant pipe 13B, and flows through the indoor heat exchanger 19 to reach the indoor expansion valve 8. The refrigerant is expanded in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. The water in the air blown out of the indoor fan 27 coagulates to adhere to the heat absorber 9 through the heat absorption operation at this time, and thus the air is cooled and dehumidified.

[0055] The refrigerant evaporated in the heat absorber 9 flows through the evaporation capacity control valve 11, the interior heat exchanger 19, and the refrigerant pipe 13C to reach the accumulator 12, and flows therethrough to be sucked into the compressor 2, thereby repeating this circulation. The air cooled and dehumidified in the heat absorber 9 is reheated in a process of passing through the heater core 4 (a heating capacity is lower than during heating), thus effecting dehumidification and cooling in the vehicle interior.

[0056] The control device 32 controls the rotational speed of the compressor 2 based on the temperature of the heat absorber 9 detected by the heat absorber temperature sensor 48, and also controls the valve position of the outdoor expansion valve 6 based on the above-described high pressure of the refrigerant circuit R, and controls a refrigerant pressure (hereinafter referred to as “radiator pressure PCI”) of the radiator 4. (5) Cooling mode

[0057] Next, in the cooling mode, the control device 32 fully opens the outdoor expansion valve 6 in the above-described state of the dehumidification and cooling mode (it sets the valve position to an upper limit of the control), and the air mixing damper 28 is in a state where the air does not pass through the radiator 4. Consequently, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 2 flows into the radiator 4. The air in the air flow channel 3 does not pass through the radiator 4, so the air only passes therethrough, and the refrigerant flowing out of the radiator 4 flows through the refrigerant pipe 13E to reach the outdoor expansion valve 6.

[0058] At this time, the outdoor expansion valve 6 is fully opened, and thus the refrigerant flows into the outdoor heat exchanger 7 as it is, where the refrigerant is cooled by passing therethrough or by the outside air passing through the outdoor fan 15 to condense and liquefy. The refrigerant flowing out of the outdoor heat exchanger 7 flows out of the refrigerant pipe 13A through the solenoid valve 17, and then flows into the header section 14 and the subcooling section 16. At this time, the refrigerant is subcooled.

[0059] The refrigerant flowing out of the subcooling section 16 of the outdoor heat exchanger 7 flows through the check valve 18 to enter the refrigerant pipe 13B, and flows through the indoor heat exchanger 19 to reach the indoor expansion valve 8. The refrigerant is expanded in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. The water in the air blown out of the indoor fan 27 coagulates and adheres to the heat absorber 9 through the heat absorption operation during this time, thus cooling the air.

[0060] The refrigerant evaporated in the heat absorber 9 flows through the evaporation capacity control valve 11, the indoor heat exchanger 19, and the refrigerant pipe 13C to reach the accumulator 12, and flows therethrough to be sucked into the compressor 2, thereby repeating this circulation. The air cooled and dehumidified in the heat absorber 9 does not pass through the heater core 4, but is blown out of the outlet 29 into the vehicle interior, thus achieving cooling in the vehicle interior.

[0061] In this cooling mode, the control device 32 controls the speed of the compressor 2 based on the temperature of the heat absorber 9, which is detected by the heat absorber temperature sensor 48. Next, the Fig. 3 to 5 are control block diagrams of the compressor 2 and the outdoor expansion valve 6 by the control device 32 in the respective operating modes described above. Fig. 3 shows the control block diagram of the control device 32, which determines a target speed (a compressor target speed) TGNCh of the compressor 2 for the above-described heating mode and the above-described dehumidifying and heating mode. An F / F control amount calculation section 58 (an open-loop control) of the control device 32 calculates an F / F control amount TGNChff of the compressor target speed based on an outside air temperature Tam obtained from the outside air temperature sensor 33, a fan electric voltage BLV of the indoor fan 27, an air mix damper opening SW of the air mix damper 28 obtained according to SW = TAO-Te) / (TH-Te), a target subcooling degree TGSC which is a target value of a subcooling degree SC in the outlet of the radiator 4, a radiator target temperature TCO which is a target value of the temperature of the radiator 4, and a radiator target pressure PCO which is a target value of the pressure of the radiator 4.

[0062] Note that TAO is a target outlet temperature, which is a target value of an air temperature from the outlet 29, TH is the temperature of the heater core 4 obtained from the heater core temperature sensor 46 (the heater core temperature), and Te is the temperature of the heat absorber 9 obtained from the heat absorber temperature sensor 48 (the heat absorber temperature). The air mixing damper opening SW changes in a range of 0≤SW≤1, where 0 indicates an air mixing cut-off state in which the air does not pass through the heater core 4, and 1 indicates a fully open air mixing state in which all the air in the air flow channel 3 passes through the heater core 4.

[0063] The above-described radiator target pressure PCO is calculated based on the above-described target subcooling degree TGSC and the radiator target temperature TCO by a target value calculation section 59. Furthermore, an F / B control variable calculation section 60 (of a controller) calculates an F / B control variable TGNChfb of the compressor target speed based on this radiator target pressure PCO and the radiator pressure PCI, which is the refrigerant pressure of the radiator 4. Furthermore, the F / F control variable TGNCnff calculated by the F / F control variable calculation section 58 and the control variable TGNChfb calculated by the F / B control variable calculation section 60 are added by an adder 61, an upper limit of control and a lower limit of control are set by a limit setting section 62, and then the compressor target speed TGNCh is determined.In the heating mode and the dehumidifying and heating mode described above, the controller 32 controls the rotational speed of the compressor 2 based on this compressor target speed TGNCh.

[0064] On the other hand, the Fig. 4 shows the control block diagram of the control device 32, which determines a target speed (a compressor target speed) TGNCc of the compressor 2 for the above-described cooling mode and the dehumidifying and cooling mode (hereinafter referred to as "normal mode"). An F / F control amount calculation section 63 of the control device 32 calculates an F / F control amount TGNCcff of the compressor target speed based on the outside air temperature Tam, the fan electric voltage BLV, and a heat absorber target temperature TEO, which is a target value of the temperature of the heat absorber 9.

[0065] In addition, an F / B control variable calculation section 64 calculates an F / B control variable TGNCcfb of the compressor target speed based on the heat absorber target temperature TEO and the heat absorber temperature Te. Furthermore, the F / F control variable TGNCcff calculated by the F / F control variable calculation section 63 and the F / B control variable TGNCcfb calculated by the F / B control variable calculation section 64 are added by an adder 66, and limits of an upper limit of control and a lower limit of control are set by a limit setting section 67, and then the compressor target speed TGNCc is determined. In the cooling mode and the normal mode of the dehumidifying and cooling mode, the control device 32 controls the speed of the compressor 2 based on this compressor target speed TGNCc.

[0066] It should be noted that in the internal cycle mode described above, the controller 32 controls the rotational speed of the compressor 2 using a small control amount at the compressor target speed TGNCh calculated for the heating mode and the dehumidifying and heating mode, and the compressor target speed TGNCc calculated for the cooling mode and the dehumidifying and cooling mode, as described above.

[0067] Next, the Fig. 5 shows the control block diagram of the control device 32, which determines a target position (an outdoor expansion valve target position) TGECCVpc of the outdoor expansion valve 6 in the dehumidification and cooling mode. An F / F control variable calculation section 68 of the control device 32 calculates an F / F control variable TGECCVpcff of the outdoor expansion valve target position based on the outside air temperature Tam, the fan electric voltage BLV, the radiator target temperature TCO, and the radiator target pressure PCO.

[0068] In addition, an F / B control variable calculation section 69 calculates an F / B control variable TGECCVpcfb of the outdoor expansion valve target position based on the radiator target pressure PCO and the radiator pressure PCI. Furthermore, the F / F control variable TGECCVpcff calculated by the F / F control variable calculation section 68 and the F / B control variable TGECCVpcfb calculated by the F / B control variable calculation section 69 are added by an adder 71, an upper limit of control and a lower limit of control are set by a limit setting section 72, and then the outdoor expansion valve target position TGECCVpc is determined. In the dehumidification and cooling mode, the control device 32 controls the valve position of the outdoor expansion valve 6 based on this outdoor expansion valve target position TGECCVpc.

[0069] The air flowing through the air flow channel 3 is subjected to the cooling operation at the heat absorber 9 and a heating operation at the heater core 4 (which is regulated by the air mixing damper 28) in the respective operation modes described above, so that it is blown into the vehicle interior from the outlet 29.The control device 32 calculates the target outlet temperature TAO based on the outside air temperature Tam detected by the outside air temperature sensor 33, the inside temperature detected by the inside air temperature sensor 37, the above-mentioned fan electric voltage, the solar radiation amount detected by the solar radiation sensor 51, and the like, and the target inside temperature (the set temperature) in the vehicle set by the operation section 53, and each operation mode is changed to control the temperature of the air blown out from the outlet 29 to this target outlet temperature TAO, which will be described later.

[0070] Next, the change control of the above-described respective operation modes by the control device 32 is carried out with reference to the Fig. 6 to 9 described. (6) Change control of operating modes

[0071] The Fig. Figure 6 shows the operating mode selected by the control device 32 of the vehicle air conditioner 1 at startup. At startup, the control device 32 selects the operating mode based on the outside air temperature Tam detected by the outside air temperature sensor 33 and the target outlet temperature TAO. Fig. 6, a dashed line L1 is a line of the target outlet temperature TAO = outside air temperature Tam, and a solid line L2 is a line of the target outlet temperature TAO = HVAC suction temperature (the temperature of the air sucked from the suction port 25 to the air flow duct 3). In addition, a dashed line L3 is a line of hysteresis set to a predetermined value (3°) above the solid line.

[0072] In the embodiment, when the outside air temperature Tam is 0°C or less at startup, the control device 32 initially selects the heating mode. In addition, when the outside air temperature Tam is higher than 0°C and the target outlet temperature TAO is the HVAC suction temperature or less, the control device selects the cooling mode. Furthermore, when the outside air temperature Tam is greater than 0°C and a predetermined value (e.g., 20°C or the like) or less, and when the target outlet temperature TAO is greater than the HVAC suction temperature, the control device selects the dehumidification and heating mode, and further, when the outside air temperature Tam is greater than the predetermined value, the control device selects the dehumidification and cooling mode. It should be noted that when the outside air humidity detected by the outside air humidity sensor 34 is a predetermined value (e.g.,50% or so) or less under conditions for selecting the dehumidification and heating mode, the controller selects the heating mode.

[0073] Next, the Fig. 7 shows an example of the operation mode change control by the control device 32 after startup. When the control device 32 executes the heating mode described above, the control device switches to the dehumidifying and heating mode in a case where the outside air temperature Tam rises to, for example, 2°C, which is 2°C higher than 0°C, or more, and the outside air humidity rises to, for example, 50% or more, based on the outside air temperature sensor 33 and the outside air humidity sensor 34. In addition, when the control device executes the heating mode, the control device skips the dehumidifying and heating mode and goes to the dehumidifying and cooling mode in a case where the outside air temperature Tam is higher than 0°C as described above, and rises to, for example, 22°C, which is 2°C higher than 20°C, or more, and the outside air humidity similarly rises to 50% or more.

[0074] In addition, when the control device 32 executes the dehumidification and heating mode described above, and when the outside air temperature Tam drops to 0°C or less and the outside air humidity drops to less than, for example, 45%, which is 5% lower than 50%, the control device switches to the heating mode.

[0075] In addition, when the control device 32 executes the dehumidification and heating mode, the control device switches to the above-described internal cycle mode in a case where the valve position of the outdoor expansion valve 6 is the above-described lower limit of the control (for example, a state where the refrigerant cannot be further compressed), and when a state in which the heat absorber temperature Te minus the heat absorber target temperature TEO is, for example, 2° or more (that is, a state in which heat absorption in the heat absorber 9 becomes low), or a state in which the radiator temperature TH minus the radiator target temperature TCO is, for example, 5° or more (that is, a state in which heat radiation in the radiator 4 becomes excessive) continues for a predetermined time or more.

[0076] In addition, when the control device 32 executes the internal cycle mode, the control device switches to the normal mode (a heat absorber temperature priority mode) of the dehumidifying and cooling mode in a case where a state in which the heat absorber temperature Te minus the heat absorber target temperature TEO is greater than, for example, 3°C than the above-described 2°C (i.e., a state in which heat absorption in the heat absorber 9 becomes further low), or a state in which the radiator temperature TH minus the radiator target temperature TCO is, for example, 10°C or more greater than the above-described 5°C (i.e., a state in which heat radiation in the radiator 4 becomes excessive), or a state in which the target outlet temperature TAO minus the HVAC suction temperature is, for example, 3°C or less continues for a predetermined time or more.

[0077] Note that when the control device executes the above-described dehumidifying and heating mode, the control device 32 can directly switch to the dehumidifying and cooling mode without switching to the internal cycle mode in a state where heat absorption in the heat absorber 9 becomes low, further switching from the above-described internal cycle mode to the dehumidifying and cooling mode, the case where heat radiation in the radiator 4 becomes further excessive, or the like. Consequently, it is possible to deal with changes in environmental conditions and the like even more quickly.

[0078] In addition, the control device 32 changes and executes the normal mode and the radiator temperature priority mode in this dehumidification and cooling mode, but these normal mode and the radiator temperature priority mode will be described in detail later. Furthermore, when the control device 32 executes the radiator temperature priority mode in this dehumidification and cooling mode, and when the radiator set temperature TCO minus the radiator temperature TH is, for example, greater than 3°C (i.e., the heat radiation in the radiator 4 becomes low), and this state continues for the predetermined time or more, the control device switches to the internal cycle mode.

[0079] In addition, when the control device 32 executes the internal cycle mode, the control device switches to the dehumidifying and heating mode in a case where a state in which the radiator target temperature TCO minus the radiator temperature TH is, for example, greater than 3° (i.e., the heat radiation in the radiator 4 becomes low), or the heat absorber target temperature TEO minus the heat absorber temperature Te is, for example, greater than 2° (i.e., the heat absorption in the heat absorber 9 is excessive), and the HVAC suction temperature (the outside air suction temperature) is, for example, 20° or less, continues for a predetermined time or more while the outside air is being introduced.

[0080] Note that when the control device executes this internal cycle mode, the control device 32 can directly switch to the heating mode without switching to the dehumidifying and heating mode, in the state where heat radiation in the radiator 4 becomes low, further from the states for switching to the dehumidifying and heating mode described above, the case where heat absorption in the heat absorber 9 becomes further excessive, or the like. Consequently, it is possible to deal with changes in environmental conditions and the like even more quickly in the same manner as described above.

[0081] Moreover, when the control device 32 executes the dehumidifying and cooling mode, and when the valve position of the outdoor expansion valve 6 is at the above-described upper limit of control (ie, a state in which the refrigerant passes as it is) and the air mix damper opening SW of the air mix damper 28 is smaller than a predetermined value, the control device switches to the cooling mode.

[0082] In addition, when the control device 32 executes this cooling mode, and when the air mix damper opening SW is the predetermined value or more and the radiator target temperature TCO is, for example, 3° or more (ie, the heat radiation in the radiator 4 becomes small), the control device switches to the dehumidifying and cooling mode.

[0083] When the control device 32 changes the operation mode in this way, it is possible to accurately change the operation mode from the dehumidifying and heating mode, the internal cycle mode, and the dehumidifying and cooling mode according to a situation in which the heat radiation in the heater core 4 or the heat absorption in the heat absorber 9 becomes small or becomes excessive under conditions such as the environment of the vehicle and the set temperature.

[0084] In addition, it is possible to precisely switch the operation mode from heating mode, dehumidification and heating mode, and dehumidification and cooling mode according to an outdoor air environment, and it is also possible to switch directly from heating mode to dehumidification and cooling mode in a situation where the outdoor air temperature continues to rise. Furthermore, it is possible to precisely switch the operation mode between cooling mode and dehumidification and cooling mode according to a control situation of the outdoor expansion valve 6 or the heat radiation situation of the radiator 4. (6-1) Other operation mode change control

[0085] It should be noted that according to the above description, it can be assumed that the internal cycle mode is the state in which the outdoor expansion valve 6 is interrupted by the control of the outdoor expansion valve 6 in the dehumidification and heating mode. Fig. 8 shows an example of the operation mode change control by the control device 32 after the start-up in the case of a control logic of the outdoor expansion valve 6 switching from the dehumidifying and heating mode to the internal cycle mode as it is.

[0086] In this case, the internal cycle mode is included in the dehumidification and heating mode. In addition, the conditions for switching from the dehumidification and heating mode to the dehumidification and cooling mode are similar to the conditions for switching to the dehumidification and cooling mode described above. (6-2) Indoor / outdoor air control

[0087] Next, the Fig. 9 shows an example of the control of the suction change damper 26 by the control device 32. As described above, the suction change damper 26 changes the outside air introduction mode for introducing the outside air into the air flow passage 3 and the inside air circulation mode for introducing the air into the vehicle, but such inside / outside air control changes at the start-up and in the stable state after the start-up.

[0088] Namely, when starting the vehicle air conditioner 1 (an absolute value of a difference between a set indoor temperature and the indoor temperature is a predetermined value or less), when the control device 32 executes the heating mode or the dehumidifying and heating mode (including the internal cycle mode), the control device switches the suction change damper 26 to the outside air introduction mode in a case where the outside air temperature obtained by the outside air temperature sensor 33 is not lower than the inside air temperature obtained by the inside air temperature sensor 37 (that is, at least a case is included where the outside air temperature is higher than an indoor temperature), or an indoor humidity obtained by the inside humidity sensor 38 is higher than the outside air humidity obtained by the outside humidity sensor 34.In addition, the control device switches the suction change damper to the indoor air circulation mode in a case where the indoor temperature is higher than the outdoor air temperature or the outdoor air humidity is not lower than the indoor humidity (ie, at least a case is included where the outdoor air humidity is higher than the indoor humidity).

[0089] In addition, when the control device 32 executes the cooling mode or the dehumidification and cooling mode at startup, the control device switches the suction change damper 26 to the indoor air circulation mode in a case where the outside air temperature is not lower than the inside air temperature (that is, at least one case is included where the outside air temperature is higher than the inside temperature), or the outside air humidity is not lower than the inside air humidity (that is, at least one case is included where the outside air humidity is higher than the inside humidity). Moreover, the control device switches the suction change damper to the outside air introduction mode in a case where the inside temperature is higher than the outside air temperature or the inside humidity is higher than the outside air humidity.

[0090] On the other hand, in the stable state after starting (the interior temperature is substantially equal to the set temperature), the control device 32 switches the suction change damper 26 to the outside air introduction mode in a case where the carbon dioxide concentration in the vehicle interior obtained from the interior air CO2 concentration sensor 39 is high and is a predetermined value or more, or the inside air circulation mode is continued in the predetermined time or more (the inside air introduction time is a predetermined value or more), or the inside humidity is greater than the outside air humidity, or the target outlet temperature TAO, which is the target value of the temperature of the air blown out of the vehicle interior, is equal to or close to the outside air temperature (a difference α).In addition, the control device switches the suction change damper to the inside air circulation mode in a case other than the above-described cases, that is, in a case where the concentration of carbon dioxide in the vehicle is less than the predetermined value, or the outside air humidity is not less than the inside air humidity, or the outside air temperature is significantly different from the target exit temperature TAO (the difference is greater than α).

[0091] When the suction change damper 26 is controlled in this way and the heating mode or the dehumidification and heating mode is executed at startup, the outside air introduction mode and the inside air circulation mode are precisely changed according to the outside air environment, so that it is possible to effectively utilize the heat in the outside air for heating in the vehicle. In addition, when the cooling mode or the dehumidification and cooling mode is executed at startup, the outside air introduction mode and the inside air circulation mode are precisely changed according to the outside air environment, so that it is possible to eliminate the adverse influence of the heat in the outside air on cooling in the vehicle, or to effectively utilize the cold in the outside air for cooling in the vehicle.In addition, it is possible to accurately change the outside air introduction mode and the inside air circulation mode according to the carbon dioxide concentration in the vehicle interior or the target outlet temperature at the stable state after starting.

[0092] Note that in the above-described embodiment, the suction change damper 26 changes the outside air introduction mode for introducing the outside air into the air flow duct 3 and the inside air circulation mode for introducing the air in the vehicle interior (the inside air). However, the present invention is not limited to this example. Between a state where all the outside air is introduced and a state where all the air in the vehicle interior is introduced, control may be performed to continuously regulate a mixing degree of the outside air and the inside air (an amount of the inside air to be mixed). Also in this case, a direction of control under the conditions of the outside air temperature, the inside air temperature, the outside air humidity, the inside air humidity, and the carbon dioxide concentration in the vehicle interior is the same as in the above-described embodiment.

[0093] Moreover, according to the vehicle air conditioner 1 of the embodiment, according to the above-described change control of the operation mode, it is possible to select and change the optimal operation mode under conditions such as the environment of the vehicle and the set temperature so that a desired air conditioning function can be performed, and the desired air conditioning function is performed so that comfortable air conditioning in the vehicle can be realized. (7) Normal mode and radiator temperature priority mode in the dehumidification and cooling mode

[0094] Next, the change control of the normal mode (the heat absorber temperature priority mode) and the radiator temperature priority mode in the dehumidifying and cooling mode described above will be explained with reference to the Fig. 10 to 22. As described above, in the normal mode of the dehumidifying and cooling mode, the rotational speed (the target rotational speed TGNCc) of the compressor 2 is controlled by the temperature of the heat absorber 9 (the heat absorber temperature Te). Therefore, even in a state (a compressed state) where the heat absorber temperature Te approaches the heat absorber target temperature TEO and the valve position of the outdoor expansion valve 6 has the above-described lower limit of control, the high pressure of the refrigerant circuit R does not rise, and the radiator pressure PCI does not reach the radiator target pressure PCO. In this case, the temperature of the radiator 4 (the radiator temperature TCO) causes a shortage.

[0095] To solve the problem, in such a case, the control device 32 executes the radiator temperature priority mode, in which the heat absorber target temperature TEO is lowered to increase the speed of the compressor 2, the high pressure lifting capability of the compressor 2 is increased, and the radiator pressure PCI is raised to the radiator target pressure PCO. Fig. 10 shows the mode change control between the normal mode and the radiator temperature priority mode in the dehumidification and cooling mode. When the controller 32 executes the dehumidification and cooling mode (the normal mode in which the heat absorber temperature is given priority), the controller switches to the radiator temperature priority mode in a case where a state in which the valve position of the outdoor expansion valve 6 is the above-described lower limit of control or less and the radiator target temperature TCO minus the radiator temperature TH is, for example, 1°C or more (i.e., the heat radiation in the radiator 4 becomes low) continues for a predetermined time or more.

[0096] The Fig. Figure 11 shows an example of a control block diagram of the control device 32 in this radiator temperature priority mode. Reference numeral 74 in the Fig. Namely, 11 denotes a data table of a heat absorber base set temperature TEO0, and this table is set in advance according to the outside air temperature. Note that this heat absorber base set temperature TEO0 is a heat absorber temperature for obtaining the humidity required for the ambient outside air temperature. Typically, the heat absorber set temperature TEO is obtained based on the data table 74, but in this radiator temperature priority mode, the controller 32 performs correction based on an integrated value of a difference between the radiator set pressure PCO and the radiator pressure PCI.

[0097] Namely, the target radiator pressure PCO and the radiator pressure PCI obtained from the radiator pressure sensor 47 are input to a subtractor 76, and a deviation E is amplified by an amplifier 77 and input to a calculator 78. The calculator 78 performs an integrative calculation of a heat absorber temperature offset in a predetermined integration time period and integration time, and an integrated value TEOPCO of the heat absorber temperature offset, which is added to a previous value by an adder 79, is calculated. Furthermore, a limit setting section 81 sets limits of the upper limit of control and the lower limit of control, and then a heat absorber temperature offset TEOPC is determined.

[0098] The heat absorber temperature offset TEOPC is subtracted from the heat absorber base set temperature TEO0 in a subtractor 82, and the heat absorber set temperature TEO is determined. Therefore, compared with the normal mode, the heat absorber set temperature TEO is lowered by as much as the heat absorber temperature offset TEOPC, thereby increasing the compressor set speed TGNCc of compressor 2, increasing the speed of compressor 2, increasing the high pressure boosting capability of compressor 2, and increasing the radiator pressure PCI, so that the required temperature PH of radiator 4 can be obtained.

[0099] It should be noted that the limit setting range 81 limits the heat absorber temperature offset TEOPC in a range in which the heat absorber 9 does not defrost. Fig. 12 shows a timing chart for explaining this behavior. It can be seen that when the outdoor expansion valve 6 is at the lower limit of control, switching to the radiator temperature priority mode under the above-described conditions, in a state where the heat absorber temperature Te approaches the heat absorber target temperature TEO and the rotational speed of the compressor 2 is low in the normal mode, the rotational speed of the compressor 2 increases, the heat absorber temperature Te decreases, and the radiator pressure PCI (or the radiator temperature TH) increases.

[0100] In this radiator temperature priority mode, on the other hand, when a state in which the heat absorber temperature offset TEOPC described above becomes zero and the radiator temperature TH minus the radiator target temperature TCO is, for example, greater than 1° (ie, the heat radiation from the radiator 4 is excessive) continues for a predetermined time or more, the control device 32 returns from the radiator temperature priority mode to the normal mode.

[0101] It should be noted that this change control of the normal mode and the radiator temperature priority mode is equally applicable to a case where the rotational speed of the compressor 2 is controlled using the compressor target speed TGNCc calculated for the cooling mode and the dehumidifying and cooling mode in the internal cycle mode.

[0102] Therefore, in the dehumidifying and cooling mode or the internal cycle mode, when the temperature TH of the heater core 4 causes a shortage even in a case where the temperature Te of the heat absorber 9 approaches the set value TEO and the valve position of the outdoor expansion valve 6 has the lower limit of control, the ability of the compressor 2 to raise the high pressure increases, and the amount of refrigerant to be irradiated in the heater core 4 is increased, so that reheating by the heater core 4 is acquired in the dehumidifying and cooling mode, thereby making it possible to acquire the air conditioning function, and an effective range of the dehumidifying and cooling mode is increased, thereby making it possible to realize the comfortable air conditioning in the vehicle.In this case, the control device 32 corrects the heat absorber target temperature TEO and lowers it in a range where the heat absorber 9 does not defrost, and thus it is possible to prevent the occurrence of icing due to an excessive temperature drop of the heat absorber 9, so that energy saving can be achieved. (7-1) Coordinated control with the electric heater

[0103] If the temperature TH of the radiator 4 does not rise to the radiator set temperature TCO even due to the increase in the speed of the compressor 2 due to the reduction of the heat absorber set temperature TEO, the electric heater 57 can be used. Fig. 13 to 15 show the control of the radiator temperature priority mode by the coordinated control with the electric heater 57. Also in this case, the conditions for switching from the normal mode to the radiator temperature priority mode are the same as in the Fig. 10. The Fig. Figure 14 shows a flowchart of the control device 32 in this case. At step S1, it is determined whether the current mode is the dehumidification and cooling mode and the radiator temperature priority mode, and if so, the step proceeds to step S2 to enable control of the electric heater 57.

[0104] The Fig. 15 shows a control block diagram of the electric heater 57 by the control device 32 when the control of the electric heater 57 is enabled. The heater target temperature TCO (may also be the heater target pressure PCO) and the heater temperature TH obtained from the heater temperature sensor 46 (may also be the heater pressure PCI) are input to a subtractor 83, and the deviation E is amplified by an amplifier 84 and input to a calculator 86. The calculator 86 performs an integrative calculation of an electric heater power Phtr for a predetermined integration period and integration time, and an integrated value of the electric heater power is calculated, which is added to the previous value by the adder 87.In addition, a limit setting section 88 sets limits of an upper limit of control and a lower limit of control, and then the electric heater power Phtr is determined.

[0105] The control device 32 drives the electric heater 57 according to a control variable of the electric heating power Phtr to generate heat, and thus the temperature deficiency of the heater core 4 is supplemented by the electric heater 57, and it is possible to realize further comfortable air conditioning in the vehicle. Note that the conditions for returning to the normal mode in this case include the electric heating power Phtr = 0 instead of the above-described heat absorber temperature offset TEOPC = 0 ( Fig. 13). (7-2) Coordinated control with the indoor fan (fan blower)

[0106] Additionally, if the air volume of the indoor fan 27 is increased, the amount of heat to be absorbed into the heat absorber 9 increases, causing the high pressure to rise, so that the radiator temperature TH increases. Instead of or in addition to this coordination with the electric heater 57, the indoor fan 27 can be coordinated to acquire the radiator temperature TH. Fig. 16 to 18 show the control of the radiator temperature priority mode by coordinating with the indoor fan 27. Also in this case, the conditions for switching from the normal mode to the radiator temperature priority mode are the same as in the Fig. 10. The Fig. 17 shows a flowchart of the control device 32 in this case. At step S3, it is determined whether the current mode is the dehumidification and cooling mode and the radiator temperature priority mode. If so, the step proceeds to step S4 to determine whether AUTO is selected for controlling the indoor fan 27 (i.e., the mode is not a manual mode). If AUTO is selected, the step proceeds to step S5 to enable coordinated control of the indoor fan.

[0107] The Fig. Fig. 18 shows a control block diagram of the indoor blower 27 by the control device 32 when the coordinated control of the indoor blower (the fan blower) 27 is enabled. The reference numeral 92 in the Fig. Namely, 18 denotes a data table of a base electric fan voltage value BLV0, and this table is set in advance according to the target outlet temperature TAO. Note that this base electric fan voltage value BLV0 is an electric fan voltage for achieving the air volume of the indoor fan 27 suitable for the target outlet temperature TAO. Conventionally, the electric fan voltage BLV is determined based on the data table 92, but in this radiator temperature priority mode, the controller 32 performs correction based on an integrated value of a difference between the radiator target temperature TCO (may also be the radiator target pressure PCO) and the radiator temperature TH (may also be the radiator pressure PCI).

[0108] Namely, the radiator target temperature TCO and the radiator temperature TH obtained from the radiator temperature sensor 46 are input to a subtractor 97, and the deviation E is amplified by an amplifier 89 and input to a calculator 91. The calculator 91 performs an integrative calculation of a fan electric voltage offset for a predetermined integration period and integration time, and an integrated value of the fan electric voltage offset is calculated, which is added to the previous value by an adder 93. Furthermore, a limit setting section 94 sets limits of an upper limit of control and a lower limit of control, and then a fan electric voltage offset BLVhtr is determined.

[0109] The electric fan voltage offset BLVhtr is added to the electric fan voltage base value BLV0 in an adder 96, and the electric fan voltage BLV is determined. Therefore, the electric fan voltage BLV is increased as much as the electric fan voltage offset BLVhtr compared to the normal mode, thereby increasing the air volume of the indoor fan 27, increasing the amount of heat to be absorbed in the heat absorber 9, increasing the high pressure to increase the radiator pressure PCI, and increasing the temperature TH of the radiator 4. Consequently, it is possible to further quickly eliminate the deficiency in the temperature of the radiator 4. Note that the conditions for returning to the normal mode are the electric fan voltage offset BLVhtr=0 instead of the heat absorber temperature offset TEOPC?0 of the Fig. 10 included ( Fig. 16). (7-3) Coordinated control with indoor / outdoor air control

[0110] In addition, indoor / outdoor air control of the outside air introduction or indoor air circulation can be coordinated to increase the radiator temperature TH. Namely, when air with a higher temperature than the indoor temperature (the indoor air temperature) and the outside air temperature is introduced into the air flow duct 3, the amount of heat to be absorbed in the heat absorber 9 increases, whereby the high pressure also increases, so that the radiator temperature TH rises. Therefore, instead of or in addition to the above-described coordination with the electric heater 57 or the indoor fan 27, indoor / outdoor air control can be coordinated by the suction change damper 26 to acquire the radiator temperature TH. Fig. 19 and Fig. 20 show the control of the radiator temperature priority mode by this coordination with the indoor / outdoor air control.

[0111] Also in this case, the conditions for switching from normal mode to radiator temperature priority mode are the same as in the Fig. 10. The Fig. Fig. 20 shows a flowchart of the control device 32 in this case. At step S6, it is determined whether the current mode is the dehumidification and cooling mode and the radiator temperature priority mode, and if so, the step proceeds to step S7 to determine whether AUTO is selected for the inside / outside air control by the suction change damper 26 (i.e., the mode is not a manual mode). If AUTO, the step proceeds to step S8 to determine whether the current mode is the outside air introduction mode.If the current mode is the outside air introduction mode, the controller 32 proceeds to step S9 to determine whether or not the indoor temperature (the inside air temperature) obtained from the inside air temperature sensor 37 is higher than the outside air temperature obtained from the outside air temperature sensor 33, and the inside air CO2 concentration obtained from the inside air CO2 concentration sensor 39 is lower than a predetermined value. Moreover, if the indoor temperature is higher than the outside air temperature and the inside air CO2 concentration is lower than the predetermined value, the step proceeds to step S10, where the suction change damper 26 is changed to the inside air circulation mode.

[0112] If the indoor air circulation mode is established at step S8, and if the outside air temperature is the indoor temperature (the inside air temperature) or higher at step S9 (that is, including the case where the outside air temperature is higher than the indoor temperature), or the indoor air CO2 concentration is the predetermined value or higher, the step proceeds to step S11. At step S11, the controller 32 determines whether the outside air temperature is higher than the indoor temperature or not, and if the outside air temperature is higher, the step proceeds to step S12, where the suction change damper 26 is changed to the outside air introduction mode. Consequently, the air having the higher temperature among the inside air and the outside air passes through the heat absorber 9.Therefore, the amount of heat to be absorbed in the heat absorber 9 is increased, and the high pressure is increased, so that it is possible to further quickly eliminate the temperature deficiency of the radiator 4. (7-4) Coordinated control with another indoor / outdoor air control

[0113] Here, the coordinated control in a case where an amount of the inside air to be mixed with the outside air can be regulated in the above-described inside / outside air control of the suction change damper 26 will be described with reference to the Fig. 21 and Fig. 22. The Fig. Fig. 21 shows a flowchart of the control device 32 in this case. At step S13, it is determined whether the current mode is the dehumidification and cooling mode and the radiator temperature priority mode, and if so, the step proceeds to step S14 to determine whether AUTO is selected for inside / outside air control by the suction change damper 26 (i.e., the mode is not a manual mode). If AUTO, the step proceeds to step S15 to enable coordinated inside / outside air control.

[0114] The Fig. Figure 22 shows a control block diagram of the suction change damper 26 by the control device 32 in a case where the coordinated inside / outside air control is enabled by the suction change damper. Reference numeral 98 in the Fig.Namely, 22 denotes a data table of an indoor air mixing ratio base value RECratio0, and in this table, a map is set in advance based on the target outlet temperature TAO and the outside air temperature Tam. Note that the indoor air mixing ratio base value RECratio0 is an indoor air mixing ratio suitable for the target outlet temperature TAO and the outside air temperature Tam at this time. Conventionally, the indoor air mixing ratio RECratio is determined based on the data table 98, but in this radiator temperature priority mode, the controller 32 performs correction based on an integrated value of a difference between the radiator target temperature TCO (may also be the radiator target pressure PCO) and the radiator temperature TH (may also be the radiator pressure PCI).

[0115] Namely, the radiator target temperature TCO and the radiator temperature TH obtained from the radiator temperature sensor 46 are input to a subtractor 101, and the deviation E is amplified by an amplifier 102 and input to a calculator 103. The calculator 103 performs an integrative calculation of an indoor air mixing ratio offset for a predetermined integration period and integration time, and an integrated value of the indoor air mixing ratio offset is calculated, which is added to the previous value at an adder 104. Furthermore, a limit setting section 106 sets limits of an upper limit of control and a lower limit of control, and then an indoor air mixing ratio offset RECratiohtr is determined.

[0116] The indoor air mixing ratio offset RECratiohtr is further corrected in an indoor / outdoor air temperature correction section 107. The indoor / outdoor air temperature correction section 107 defines the indoor air mixing ratio offset RECratiohtr as a correction in a direction (+) for increasing the indoor air mixing ratio when the indoor temperature is the outside air temperature or higher, or conversely as a correction in a direction (-) for decreasing the indoor air mixing ratio when the outside air temperature is higher than the indoor temperature, and the offset is then added to an indoor air mixing ratio base value RECratio0 in an adder 99, and the indoor air mixing ratio RECratio is determined.

[0117] Therefore, when the indoor temperature is higher than the outdoor air temperature, the indoor air mixing ratio RECratio is increased by as much as the indoor air mixing ratio offset RECratiohtr compared to the normal mode, thereby increasing the amount of heat to be absorbed in the heat absorber 9, the high pressure rises to increase the radiator pressure PCI, and the temperature TH of the radiator 4 rises. Consequently, it is possible to further quickly eliminate the temperature deficiency of the radiator 4.

[0118] It should be noted that the structure of the refrigerant circuit R and the respective numerical values ​​are not limited to those described in the above-described embodiment, and needless to say, they can be changed without departing from the scope of the present invention. LIST OF REFERENCE SYMBOLS 1 vehicle air conditioning system 2 compressors 3 Air flow channel 4 radiators 6 Outdoor expansion valve 7 outdoor heat exchangers 8 Internal expansion valve 9 heat absorbers 11 Evaporation capacity control valve 17, 21, 22 and 23 solenoid valve 26 suction change damper 27 internal fans (one fan blower) 28 air mixing damper 32 Control device (control equipment) 57 electric heater R coolant circuit

Claims

[1] Vehicle air conditioning system (1) with: a compressor (2) which compresses a coolant; an air flow duct (3) through which air flows to be supplied to a vehicle interior; a heater (4) arranged in the air flow channel (3) to cause the coolant to radiate heat; a heat absorber (9) arranged in the air flow channel (3) to cause the coolant to absorb heat; an external heat exchanger (7) arranged outside the vehicle interior for causing the coolant to radiate or absorb heat; and a control device (32), wherein the control device (32) is configured to change and execute at least one of the following: a heating mode in which the refrigerant discharged from the compressor (2) radiates heat in the radiator (4), and the refrigerant from which heat is radiated is expanded and then absorbs heat in the outdoor heat exchanger (7); a dehumidifying and heating mode in which the refrigerant discharged from the compressor (2) radiates heat in the radiator (4), and the refrigerant from which the heat has been radiated is expanded and then absorbs heat only in the heat absorber (9) or in the heat absorber (9) and the outdoor heat exchanger (7); a dehumidification and cooling mode in which the refrigerant discharged from the compressor (2) radiates heat in the radiator (4) and the outdoor heat exchanger (7), and the refrigerant from which the heat has been radiated is expanded and then absorbs heat in the heat absorber (9); and a cooling mode in which the coolant discharged from the compressor (2) radiates heat in the outdoor heat exchanger (7), and the coolant from which the heat has been radiated is expanded and then absorbs heat in the heat absorber (9), wherein the control device (32) is designed to switch to the dehumidification and cooling mode based on a situation in which a difference (Te - TEO) of a heat absorber temperature (Te) and a heat absorber target temperature (TEO) is greater than a predetermined value or a difference (TH - TCO) of a radiator temperature (TH) and a radiator target temperature (TCO) is a predetermined value or more in the dehumidification and heating mode, and wherein the control device (32) is further configured to switch to the dehumidifying and heating mode based on a situation in which a difference (TCO - TH) of the radiator target temperature (TCO) and the radiator temperature (TH) is greater than a predetermined value in the dehumidifying and cooling mode. [2] Vehicle air conditioning system (1) according to claim 1, wherein the control device (32) in the dehumidification and heating mode has an internal cycle mode in which the coolant is prohibited from flowing into the outdoor heat exchanger (7) and the coolant absorbs heat only in the heat absorber (9), wherein the control device (32) is designed to switch to the internal cycle mode based on a situation in which a difference (Te - TEO) of a heat absorber temperature (Te) and a heat absorber target temperature (TEO) is less than a predetermined value or a difference (TH - TCO) of a radiator temperature (TH) and a radiator target temperature (TCO) in the dehumidification and heating mode is a predetermined value or more, and wherein the control device (32) is further configured to switch to the dehumidifying and cooling mode based on a situation in which a difference (Te - TEO) of a heat absorber temperature (Te) and a heat absorber target temperature (TEO) is further smaller than a predetermined value or a difference (TH - TCO) of a radiator temperature (TH) and a radiator target temperature (TCO) is further a predetermined value or more in this internal cycle mode. [3] Vehicle air conditioning system (1) according to claim 2, wherein the control device (32) is designed to switch to the internal cycle mode based on the situation in which a difference (TCO - TH) of a radiator target temperature (TCO) and a radiator temperature (TH) in the dehumidification and cooling mode does not reach a predetermined value, and wherein the control device (32) is further configured to switch to the dehumidifying and heating mode based on the situation in which a difference (TCO - TH) of a radiator target temperature (TCO) and a radiator temperature (TH) does not reach a predetermined value or a difference (Te - TEO) of a heat absorber temperature (Te) and a heat absorber target temperature (TEO) in this internal cycle mode is a predetermined value or more. [4] Vehicle air conditioning system (1) according to one of claims 1 to 3, wherein the control device (32) is adapted to switch from the heating mode to the dehumidifying and heating mode or the dehumidifying and cooling mode based on a situation in which an outside air temperature and an outside air humidity increase, and to switch from the dehumidifying and heating mode and the dehumidifying and cooling mode to the heating mode based on a situation in which the outside air temperature and the outside air humidity decrease. [5] The vehicle air conditioner (1) according to claim 4, wherein the control device (32) is configured to switch from the heating mode to the dehumidifying and cooling mode based on a situation in which the outside air temperature rises to a temperature higher than a temperature of a condition for switching from the heating mode to the dehumidifying and heating mode. [6] Vehicle air conditioning system (1) according to one of claims 1 to 5, which has an external expansion valve (6) which expands the coolant flowing into the external heat exchanger (7), wherein the control device (32) is designed to determine an outdoor expansion valve target position (TGECCVpc) and to control a valve position of an outdoor expansion valve (6) on the basis of the outdoor expansion valve target position (TGECCVpc), wherein an upper limit of control and a lower limit of control are set by a limit setting section (72), wherein the control device (32) is further configured to switch from the dehumidifying and cooling mode to the cooling mode based on a situation in which the valve position of the outdoor expansion valve (6) reaches the upper limit of the control, and wherein the control device (32) is configured to switch from the cooling mode to the dehumidifying and cooling mode based on the situation in which the difference (TCO - TH) of the radiator target temperature (TCO) and the radiator temperature (TH) is a predetermined value or more. [7] Vehicle air conditioning system (1) according to one of claims 1 to 6, which has a suction change damper (26) which changes an outside air introduction mode for introducing the outside air into the air flow duct (3) and an inside air circulation mode for introducing the air in the vehicle interior into the air flow duct (3), wherein, when the control device (32) executes the heating mode or the dehumidification and heating mode at startup, the control device (32) switches the suction change damper (26) to the outside air introduction mode in a case where at least the outside air temperature is higher than an inside temperature or at least an inside humidity is higher than an outside air humidity, and to the inside air circulation mode in a case where at least the inside temperature is higher than the outside air temperature or at least the outside air humidity is higher than the inside humidity. [8] Vehicle air conditioning system (1) according to one of claims 1 to 7, which has a suction change damper (26) which changes an outside air introduction mode for introducing the outside air into the air flow duct (3) and an inside air circulation mode for introducing the air in the vehicle interior into the air flow duct (3), wherein, when the control device (32) executes the cooling mode or the dehumidification and cooling mode at startup, the control device (32) switches the suction change damper (26) to the inside air circulation mode in a case where at least the outside air temperature is higher than the inside temperature or at least the outside air humidity is higher than the inside humidity, and to the outside air introduction mode in a case where at least the inside temperature is higher than the outside air temperature or at least the inside humidity is higher than the outside air humidity. [9] The vehicle air conditioner (1) according to claim 7 or claim 8, wherein, in a stable state after start-up, the control means (32) switches the suction change damper (26) to the outside air introduction mode in a case where a carbon dioxide concentration in the vehicle interior is high, or the inside air circulation mode continues for a predetermined time or more, or the inside humidity is higher than the outside air humidity, or a set value of a temperature of the air blown into the vehicle interior is equal to the outside air temperature, and the control means (32) switches the suction change damper (26) to the inside air circulation mode under conditions different from the above-described conditions.

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