Vehicle air conditioning

Abstract

Vehicle air conditioning system (1), comprising: a compressor (2) which compresses a refrigerant; a radiator (4) which radiates heat from the refrigerant to heat air to be supplied into a vehicle interior; an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat; an expansion valve (6) which decompresses the refrigerant flowing into the outdoor heat exchanger (7); and a control means (32), wherein the control means (32) is configured to allow the refrigerant discharged from the compressor (2) to radiate heat in the radiator (4), to decompress the refrigerant through which heat has been radiated through the expansion valve (6) and then to absorb heat in the outdoor heat exchanger (7), thereby heating the vehicle interior, wherein the control means (32) is configured to control a degree of subcooling (SC) of the refrigerant in the radiator (4) through the expansion valve (6) and to control a rotational speed (NC) of the compressor (2) based on a high pressure (Pci), and a high pressure priority mode to increase a target radiator subcooling degree (TGSC) of the radiator (4) so that the high pressure (Pci) is set to a predetermined high value, and has a speed priority mode to reduce the target radiator subcooling degree (TGSC) of the radiator (4) so that the speed (NC) of the compressor (2) is set to a predetermined high value.

Description

Technical field

[0001] The present invention relates to a vehicle air conditioner of a heat pump system that conditions air in a vehicle interior, and more particularly, to a vehicle air conditioner applicable to a hybrid car or an electric car. State of the art

[0002] Due to an update of environmental problems in recent years, hybrid cars and electric cars have become widespread. In addition, as an air conditioner applicable to such a vehicle, an air conditioner has been developed that includes a compressor for compressing and discharging a refrigerant, a radiator (a condenser) arranged on a vehicle interior side to allow the refrigerant to radiate heat, a heat absorber (an evaporator) arranged on the vehicle interior side to allow the refrigerant to absorb heat, and a refrigerant circuit consisting of an outdoor heat exchanger arranged outside the vehicle interior to allow the refrigerant to radiate or absorb heat, and that has respective operation modes, such as a heating mode in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant,through which heat was radiated in this radiator, absorbs heat in the outdoor heat exchanger, a dehumidification mode in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant through which heat was radiated in the radiator absorbs heat in the heat absorber, and a cooling mode in which the refrigerant discharged from the compressor radiates heat in the outdoor heat exchanger and absorbs heat in the heat absorber (e.g. see JP 3 985 384 B2 or DE 10 2012 215 622 A1), switches and executes.,

[0003] In addition, in JP 3 985 384 B2, an injection circuit which disperses the refrigerant discharged from the radiator, decompresses this dispersed refrigerant, performs heat exchange between this refrigerant and the refrigerant discharged from the radiator, and then returns the refrigerant to the center of compression by the compressor in the heating mode is arranged, thereby increasing the refrigerant to be discharged from the compressor and improving a heating ability by the radiator.

[0004] In DE 10 2012 215 622 A1, a target radiator subcooling level is also controlled in order to increase the operating efficiency (COP). Summary of the inventionProblems to be solved by the invention

[0005] In a conventional automotive air conditioning system, a control upper limit (a control upper limit) is set for a compressor speed. This means that the compressor speed cannot be set above this control upper limit. In addition, a high pressure of a refrigerant circuit also has an upper control limit to protect the compressor. Thus, when a refrigerant subcooling degree in a radiator is high and the high pressure is above the control upper limit, control is performed to reduce the compressor speed while suppressing the high pressure.

[0006] The high pressure can be maintained at the upper control limit or lower, but at this time, the rotational speed of the compressor decreases, and thus a refrigerant flow rate is small and a heating ability by the radiator becomes scarce, which has caused the problem that a required heating ability cannot be satisfied.

[0007] The present invention has been developed to solve such a conventional technical problem, and it is an object thereof to provide a vehicle air conditioner in which a refrigerant supercooling degree of a radiator can be appropriately controlled to satisfy both a high pressure and a refrigerant fluid flow rate during heating to achieve an improvement in heating ability. Means to solve the problems

[0008] A vehicle air conditioner of the present invention includes a compressor that compresses a refrigerant, a radiator that allows the refrigerant to radiate heat to heat air to be supplied into the vehicle interior, an outdoor heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, an expansion valve that decompresses the refrigerant flowing into this outdoor heat exchanger, and a control means, wherein this control means is configured to allow the refrigerant discharged from the compressor to radiate heat in the radiator, to decompress the refrigerant through which heat has been radiated by the expansion valve and then to absorb heat in the outdoor heat exchanger, thereby heating the vehicle interior, the vehicle air conditioner being characterized in thatthat the control means controls a degree of subcooling of the refrigerant in the radiator through the expansion valve and controls a rotational speed of the compressor based on a high pressure, and has a high pressure priority mode for increasing a target radiator subcooling degree of the radiator in a direction in which the high pressure is set to a predetermined high value, and a rotational speed priority mode for decreasing the target radiator subcooling degree of the radiator in a direction in which the rotational speed of the compressor is set to a predetermined high value.,

[0009] The vehicle air conditioner of the invention of claim 2 is characterized in that the control means in the above invention switches and executes the high pressure priority mode and the speed priority mode, while changing the target radiator supercooling degree of the radiator to maintain the speed of the compressor high while maintaining the high pressure at the predetermined high value.

[0010] The vehicle air conditioner of the invention of claim 3 is characterized in that the control means in the above invention executes the high pressure priority mode to increase the target radiator subcooling degree of the radiator in the direction in which the high pressure is set to the predetermined high value, switches to the speed priority mode in a case where the high pressure reaches the predetermined high value, and decreases the target radiator subcooling degree of the radiator in the direction in which the speed of the compressor is set to the predetermined high value.

[0011] The vehicle air conditioner of the invention of claim 4 is characterized in that in the respective above inventions, the control means in the high pressure priority mode increases the target radiator subcooling degree of the radiator in a direction in which the high pressure is set to an upper control limit value, and the control means in the speed priority mode decreases the target radiator subcooling degree of the radiator in a direction in which the speed of the compressor is set to an upper limit value.

[0012] The vehicle air conditioner of the invention of claim 5 is characterized in that in the above invention, in the high pressure priority mode, the control means performs feedback correction of the target radiator subcooling degree of the radiator based on a deviation between the upper control limit of the high pressure and an actual high pressure, and the control means performs the feedback correction of the target radiator subcooling degree of the radiator based on a deviation between the upper control limit of the rotational speed of the compressor and an actual rotational speed in the speed priority mode.

[0013] The vehicle air conditioner of the invention of claim 6 is characterized in that the control means in the above respective inventions has efficiency priority control and capability priority control, and the control means in the efficiency priority control determines the target radiator subcooling degree of the radiator based on a volume of air to be passed through the radiator, and in a case where conditions in which heating capability by the radiator becomes scarce arise, switches to capability priority control, and the control means in this capability priority control executes the high pressure priority mode and the speed priority mode, and corrects the target radiator subcooling degree of the radiator.

[0014] The vehicle air conditioner of the invention of claim 7 is characterized in that the above invention comprises an injection circuit that distributes a part of the refrigerant flowing out from the radiator to return the part of the refrigerant to the compressor, and the control means changes conditions to switch to the capability priority control in a case where the injection circuit returns the part of the refrigerant flowing out from the radiator to the compressor and in a case where the injection circuit does not return the part of the refrigerant to the compressor. Advantageous effect of the invention

[0015] According to the present invention, a control means has a high-pressure priority mode for increasing a target radiator subcooling degree of a radiator in a direction in which a high pressure is set to a predetermined high value, and a speed priority mode for decreasing the target radiator subcooling degree of the radiator in a direction in which a rotational speed of a compressor is set to a predetermined high value. Therefore, as in the invention of claim 2, the control means switches and executes the high-pressure priority mode and the speed priority mode, thereby changing the target radiator subcooling degree of the radiator to maintain the rotational speed of the compressor high while maintaining the high pressure at the predetermined high value, so that during heating, a refrigerant flow rate is obtained even while maintaining the high pressure, and it is possible to improve heating capability.

[0016] In this case, for example, as in the invention of claim 3, the control means executes the high pressure priority mode to increase the target radiator subcooling degree of the radiator in the direction in which the high pressure is set to the predetermined high value, switches to the speed priority mode in a case where the high pressure reaches the predetermined high value, and decreases the target radiator subcooling degree of the radiator in the direction in which the speed of the compressor is set to the predetermined high value, so that it is possible to appropriately control a refrigerant subcooling degree of the radiator that satisfies both the high pressure and the refrigerant flow rate.

[0017] Specifically, as in the invention of claim 4, in the high-pressure priority mode, the control means increases the target radiator subcooling degree of the radiator in a direction in which the high pressure is set to an upper control limit, and in the speed priority mode, the control means decreases the target radiator subcooling degree of the radiator in a direction in which the rotational speed of the compressor is set to an upper limit. Consequently, the rotational speed of the compressor is increased to also maintain the refrigerant flow rate while appropriately controlling the refrigerant subcooling degree of the radiator to suppress the high pressure to the upper control limit or less, and thus the heating capability can be improved.

[0018] In this case, as in the invention of claim 5, in the high pressure priority mode, the control means performs feedback correction of the target radiator subcooling degree of the radiator based on a deviation between the upper control limit of the high pressure and a current high pressure, and in the speed priority mode, the control means performs the feedback correction of the target radiator subcooling degree of the radiator based on a deviation between the upper control limit of the speed of the compressor and an actual speed, so that it is possible to always stably realize the correction of the refrigerant subcooling degree of the radiator.

[0019] In addition, as in the invention of claim 6, the control means has efficiency priority control and capability priority control. In the efficiency priority control, the control means determines the target radiator subcooling degree of the radiator based on an air volume to be passed through the radiator, and switches to capability priority control in a case where conditions arise in which a heating capability by the radiator becomes scarce. In this capability priority control, the control means executes the high-pressure priority mode and the speed priority mode and corrects the target radiator subcooling degree of the radiator. Therefore, the control means always executes the efficiency priority control and can execute the capability priority control to execute the high-pressure priority mode and the speed priority mode only in a case where the heating capability of the radiator becomes scarce.

[0020] Consequently, the improvement in heating ability can be achieved while minimizing deterioration of operating efficiency, and thus the present invention is remarkably suitable in a vehicle such as an electric car or a hybrid car that drives the compressor with energy charged in a battery.

[0021] Moreover, when the vehicle air conditioner has an injection circuit that distributes a part of the refrigerant flowing out from the radiator to return the part of the refrigerant to the compressor, as in the invention of claim 7, the control means changes conditions to switch to the capability priority control in a case where the injection circuit returns the part of the refrigerant flowing out from the radiator to the compressor and in a case where the injection circuit does not return the part of the refrigerant to the compressor, so that it is possible to appropriately correct the refrigerant supercooling degree of the radiator in consideration of the improvement in heating capability due to the increase in an amount of the refrigerant to be discharged from the compressor by injection. Short description of the drawings Fig. 1 is a structural view of a vehicle air conditioner of an embodiment to which the present invention is applied; Fig. 2 is a block diagram of an electrical circuit of a control device of a vehicle air conditioning system of Fig. 1; Fig. 3 is a Ph diagram of the vehicle air conditioning system of Fig. 1 during an injection; Fig. 4 is a control block diagram of the control device of Fig. 2 during heating; Fig. 5 is a diagram to illustrate a determination of a target outlet temperature by the control device of Fig. 2 to explain; Fig. 6 is a control block diagram of a compressor speed calculation section of Fig. 4; Fig. 7 is a control block diagram relating to a determination of a target radiator subcooling level by the controller of Fig. 2; Fig. Fig. 8 is a diagram for illustrating a determination method of the target radiator subcooling degree during efficiency priority control by the controller of Fig. 2 to explain; Fig. 9 is a control block diagram relating to a correction of the target radiator subcooling degree during capability priority control by the controller of Fig. 2; Fig. 10 is a flowchart to illustrate an operation of the control device of Fig. 2 to explain; Fig. 11 is a timing chart to show the operation of the control device of Fig. 2 to explain; and Fig. 12 is a diagram for illustrating a target radiator subcooling degree correction operation of another embodiment of the control device of Fig. 2 to explain. Mode for carrying out the invention

[0022] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0023] Fig. 1 shows a structural 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 car (EV) that does not have an internal combustion engine (an internal combustion engine) and travels by power charged in a battery (not shown) by driving an electric motor. The vehicle air conditioner 1 of the present invention is also driven by the power of the battery. That is, in the electric car in which heating cannot be performed 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 performs respective operation modes of dehumidifying and heating, cooling and dehumidifying, cooling, and the like.

[0024] It should be noted that the vehicle is not limited to the electric car, and the present invention is also effective for a so-called hybrid car in which the internal combustion engine is used together with the electric motor for driving, and needless to say, it is also applicable to an ordinary car running by the internal combustion engine.

[0025] The vehicle air conditioner 1 of the embodiment performs air conditioning (heating, cooling, dehumidification, and ventilation) in the electric car, and includes an electric compressor 2 that compresses a refrigerant; a radiator 4 arranged in an airflow passage 3 of an HVAC unit in which air is circulated and circulated in the vehicle interior; an outdoor expansion valve 6 formed by an electric valve that decompresses and expands the refrigerant during heating; an outdoor heat exchanger 7 that performs heat exchange between the refrigerant and outside air to function as the radiator during cooling and as an evaporator during heating; and an indoor expansion valve 8 formed by an electric valve that decompresses and expands the refrigerant.a heat absorber 9 arranged in the airflow passage 3 for allowing the refrigerant to absorb heat from an interior and an exterior of the vehicle during cooling and dehumidification; an evaporation capacity control valve 11 that regulates evaporation capacity in the heat absorber 9; an accumulator 12, and the like are sequentially connected by a refrigerant pipe 13 to form a refrigerant circuit R. Note that an outdoor fan 15 is arranged in the outdoor heat exchanger 7 to perform heat exchange between the outside air and the refrigerant.

[0026] In addition, the outdoor heat exchanger 7 has, on a refrigerant downstream side, a liquid tank with dryer section 14 and a subcooling section 16 sequentially. A refrigerant pipe 13A extending from the outdoor heat exchanger 7 is connected to the liquid tank with dryer section 14 via a solenoid valve (an opening / closing valve) 17 that is opened during cooling, and an outlet of the subcooling section 16 is connected to the indoor expansion valve 8 via a check valve 18. Note that the liquid tank with dryer section 14 and the subcooling section 16 structurally constitute a part of the outdoor heat exchanger 7, and a side of the indoor expansion valve 8 from the check valve 18 is a forward direction.

[0027] In addition, a refrigerant pipe 13B is arranged between the check valve 18 and the indoor expansion valve 8 in a heat-exchanging 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 of the pipes form an internal 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 from the heat absorber 9 through the evaporability control valve 11.

[0028] In addition, the refrigerant pipe 13A extending from the outdoor heat exchanger 7 is branched, and this branched refrigerant pipe 13D communicates to be connected to the refrigerant pipe 13C on the downstream side of the indoor heat exchanger 19 via a solenoid valve (an opening / closing valve) 21 to be opened during heating. Furthermore, a refrigerant pipe 13E on an outlet side of the radiator 4 is branched before the outdoor expansion valve 6, and this branched refrigerant pipe 13F communicates to be connected to the refrigerant pipe 13B on the downstream side of the check valve 18 via a solenoid valve (an opening / closing valve) 22 to be opened during dehumidification.

[0029] In addition, a bypass pipe 13J is connected in parallel to the outdoor expansion valve 6, and in the bypass pipe 13J, a solenoid valve (an opening / closing valve) 20, which is opened in a cooling mode and bypasses the outdoor expansion valve 6 to bypass the refrigerant, is arranged.

[0030] In addition, immediately after the pipe extends from the radiator 4 (before the pipe branches into refrigerant pipes 13F and 13I), the refrigerant pipe 13E is branched, and this branched refrigerant pipe 13K communicates to be connected to the center of compression by the compressor 2 via an injection expansion valve 30 formed by an electric valve for injection control. Further, the refrigerant pipe 13K is arranged between an outlet side of the injection expansion valve 30 and the compressor 2 in heat-exchanging relationship with a refrigerant pipe 13G positioned on a discharge side of the compressor 2, and both of the pipes constitute a discharge-side heat exchanger 35.

[0031] The refrigerant pipe 13K, the injection expansion valve 30, and the discharge-side heat exchanger 35 form an injection circuit 40. The injection circuit 40 is a circuit that distributes part of the refrigerant flowing out from the radiator 4 to return the part of the refrigerant to the center of compression by the compressor 2 (gas injection). In addition, the injection expansion valve 30 decompresses the refrigerant flowing into the refrigerant pipe 13K, and then the refrigerant flows into the discharge-side heat exchanger 35. The refrigerant flowing into the discharge-side heat exchanger 35 is discharged from the compressor 2 to the refrigerant pipe 13G, performs heat exchange with the refrigerant before flowing into the radiator 4, and absorbs heat from the refrigerant flowing through the refrigerant pipe 13G to evaporate.In the discharge-side heat exchanger 35, the refrigerant distributed to the refrigerant pipe 13K evaporates, whereby the gas injection into the compressor 2 is carried out.

[0032] In addition, on an air upstream side of the heat absorber 9, respective intake ports such as an outside air intake port and an inside air intake port are formed in the air flow passage 3 (by an intake port 25 in Fig. 1), and in the intake port 25, an intake change damper 26 is arranged to change the air to be introduced into the airflow passage 3 into indoor air, which is air in the vehicle interior (an indoor air circulation mode), and outside air, which is air outside the vehicle interior (an outside air introduction mode). Further, an indoor blower (a blower fan) 27 is arranged on an air downstream side of the intake change damper 26 to supply the introduced indoor air or outside air to the airflow passage 3.

[0033] In addition, an air mixing damper 28 is arranged in the air flow passage 3 on the air upstream side of the radiator 4 to regulate a flow rate of the indoor air or the outdoor air through the radiator 4. Furthermore, in the air flow passage 3 on an air downstream side of the radiator 4, any foot, ventilation or defrost outlet (through an outlet 29 in Fig. 1), and in the outlet 29, an outlet change valve 31 is arranged to carry out change control of blowing the air from any outlet mentioned above.

[0034] Next is Fig. 2, a control unit (ECU) 32 as a control means formed by a microcomputer, and an input of the control unit 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 intake temperature sensor 36 that detects a temperature of air to be sucked in from the intake port 25 to the airflow passage 3, an indoor air temperature sensor 37 that detects a temperature of the air in the vehicle interior (the interior air), an indoor air humidity sensor 38 that detects a humidity of the air in the vehicle interior, an indoor 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 out from the outlet 29 into the vehicle interior, a discharge pressure sensor 42,which detects a pressure of the refrigerant discharged from the compressor 2, a discharge temperature sensor 43 which detects a temperature of the refrigerant discharged from the compressor 2, a suction pressure sensor 44 which detects a refrigerant suction pressure of the compressor 2, a radiator temperature sensor 46 which detects a temperature of the radiator 4 (the temperature of the air that has just flowed out from the radiator 4, or the temperature of the radiator 4 itself, or the temperature of the air that has just been heated in the radiator 4), a radiator pressure sensor 47 which detects a refrigerant pressure of the radiator 4 (the pressure in the radiator 4 or the pressure of the refrigerant that has just flowed out from the radiator 4), a heat absorber temperature sensor 48 which detects a temperature of the heat absorber 9 (the temperature of the air that has just flowed out from the heat absorber 9, or the temperature of the heat absorber 9 itself, or the temperature of the air,which has just been cooled in the heat absorber 9), a heat absorber pressure sensor 49 which detects a refrigerant pressure of the heat absorber 9 (the pressure in the heat absorber 9, or the pressure of the refrigerant that has just flowed out from the heat absorber 9), a solar radiation sensor 51 of, for example, a photo sensor system for detecting an amount of solar radiation into the vehicle, a speed sensor 52 for detecting a moving speed of the vehicle (a speed), an air conditioning operating section 53 for adjusting the change of the set temperature or the operation mode, an outdoor heat exchanger temperature sensor 54 which detects a temperature of the outdoor heat exchanger 7 (the temperature of the refrigerant that has just flowed out from the outdoor heat exchanger 7, or the temperature of the outdoor heat exchanger 7 itself), and an outdoor heat exchanger pressure sensor 56,which detects the refrigerant pressure of the outdoor heat exchanger 7 (the pressure of the refrigerant in the outdoor heat exchanger 7 or the refrigerant that has just flowed out of the outdoor heat exchanger 7).

[0035] In addition, the input of the controller 32 is further connected to respective outputs of an injection pressure sensor 50 that detects a pressure of an injection refrigerant flowing into the refrigerant pipe 13K of the injection circuit 40 and flowing through the discharge-side heat exchanger 35 to return to the center of compression by the compressor 2, and an injection temperature sensor 55 that detects a temperature of the injection refrigerant.

[0036] On the other hand, an output of the controller 32 is connected to the compressor 2, the outdoor blower 15, the indoor blower (the blower fan) 27, the intake change valve 26, the air mix valve 28, the exhaust change valve 31, the outdoor expansion valve 6, the indoor expansion valve 8, the respective solenoid valves 22, 17, 21, and 20, the injection expansion valve 30, and the evaporative capability control valve 11. Further, the controller 32 controls these components based on the outputs of the respective sensors and the setting inputs from the air conditioning operation section 53.

[0037] Next, an operation of the vehicle air conditioner 1 of the embodiment having the above-mentioned configuration will be described. The controller 32 changes and executes roughly differentiated operation modes, such as a heating mode, a dehumidifying and heating mode, an internal circulation mode, a dehumidifying and cooling mode, and a cooling mode. First, the flow of the refrigerant in each operation mode will be described. (1) Refrigerant flow of a heating mode

[0038] When the heating mode is selected by the controller 32 or a manual operation on the air conditioning operating section 53, the controller 32 opens the solenoid valve 21 and closes the solenoid valve 17, the solenoid valve 22, and the solenoid valve 20. Furthermore, the compressor 2 and the respective blowers 15 and 27 are operated, and the air mix damper 28 is in a state where the air blown by the indoor blower 27 is passed through the radiator 4. Consequently, a high-temperature, high-pressure refrigerant gas discharged from the compressor 2 flows through the discharge-side heat exchanger 35 and then flows into the radiator 4.The air in the airflow passage 3 is passed through the radiator 4, and thus the air in the airflow passage 3 is heated by the high-temperature refrigerant in the radiator 4, whereas the refrigerant is extracted from heat by the air in the radiator 4 and cooled to condense and liquefy.

[0039] The refrigerant liquefied in the radiator 4 flows out from the radiator 4. A part of the refrigerant is then distributed to the refrigerant pipe 13K of the injection circuit 40, and the refrigerant flows mainly through the refrigerant pipe 13E to reach the outdoor expansion valve 6. Note that a function and operation of the injection circuit 40 will be described later. The refrigerant flowing into the outdoor expansion valve 6 is decompressed therein and then flows into the outdoor heat exchanger 7. The refrigerant flowing into the outdoor heat exchanger 7 evaporates, and heat is pumped by the outside air passing through a motor or the outdoor fan 15 (heat pump).Further, the low-temperature refrigerant flowing out from the outdoor heat exchanger 7 flows through the refrigerant pipe 13D and the solenoid valve 21 to flow from the refrigerant pipe 13C into the accumulator 12, where gas-liquid separation is performed, and then the refrigerant gas is sucked into the compressor 2, repeating this cycle. The air heated in the radiator 4 is exhausted from the outlet 29, thus heating the vehicle interior.

[0040] As described later in the embodiment, the controller 32 controls a rotational speed of the compressor 2 based on a high pressure of the refrigerant circuit R detected by the radiator pressure sensor 47 (or the discharge pressure sensor 42), and also controls a valve position of the outdoor expansion valve 6 based on an air volume to be passed through the radiator 4 and a target outlet temperature mentioned below, and controls a supercooling degree of the refrigerant in the outlet of the radiator 4. Note that the valve position of the outdoor expansion valve 6 may be controlled based on a temperature of the radiator 4 or an outside air temperature instead of or in addition to the above conditions. (2) Refrigerant flow of a dehumidifying and heating mode

[0041] In the above state of the heating mode, the controller 32 next opens the solenoid valve 22 in the dehumidifying and heating mode. Consequently, part of the condensed refrigerant flowing through the radiator 4 and the refrigerant pipe 13E is dispersed and flows through the solenoid valve 22 to flow from the refrigerant pipes 13F and 13B through the internal heat exchanger 19, thereby reaching the indoor expansion valve 8. The refrigerant is decompressed in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. Water in the air blown out by the indoor blower 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.

[0042] The refrigerant evaporated in the heat absorber 9 flows through the evaporation capability control valve 11 and the internal heat exchanger 19 to combine with the refrigerant from the refrigerant pipe 13D in the refrigerant pipe 13C, and then flows through the accumulator 12 to be sucked into the compressor 2, repeating this cycle. The air dehumidified in the heat absorber 9 is reheated in a process of passing through the radiator 4, thus performing dehumidification and heating in the vehicle interior.

[0043] The controller 32 controls the rotational speed of the compressor 2 based on the high pressure of the refrigerant circuit R detected by the discharge 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. Note that gas injection by the injection circuit 40 is not performed in this dehumidification and heating mode, and thus the injection expansion valve 30 is shut off (a shutoff position). (3) Refrigerant flow of an internal circulation mode

[0044] In the above state of the dehumidifying and heating mode, the controller 32 next shuts off the outdoor expansion valve 6 (a shut-off position) in the internal circulation mode, and also closes the solenoid valve 21. The outdoor expansion valve 6 and the solenoid valve 21 are closed, blocking inflow of the refrigerant into the outdoor heat exchanger 7 and outflow of the refrigerant from 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. Further, the refrigerant flowing through the refrigerant pipe 13F flows from the refrigerant pipe 13B through the internal heat exchanger 19 to reach the indoor expansion valve 8. The refrigerant is decompressed in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate.The water in the air blown out by the indoor blower 27 coagulates to adhere to the heat absorber 9 by the heat absorption operation at this time, and thus the air is cooled and dehumidified.

[0045] The refrigerant evaporated in the heat absorber 9 flows through the evaporation capability control valve 11, the internal heat exchanger 19, the refrigerant pipe 13C, and the accumulator 12 to be sucked into the compressor 2, repeating this cycle. The air dehumidified in the heat absorber 9 is reheated by passing through the radiator 4, thus performing dehumidification and heating in the vehicle interior. However, in this internal circulation mode, the refrigerant circulates between the radiator 4 (heat radiation) and the heat absorber 9 (heat absorption) located on an interior side in the airflow passage 3, and thus, heat is not drawn in from the outside air, but heating capability is exerted for consumed energy of the compressor 2.The entire amount of refrigerant flows through the heat absorber 9, which performs a dehumidifying operation, and thus, compared with the above dehumidifying and heating operation mode, a dehumidifying ability is high, but the heating ability decreases.

[0046] The controller 32 controls the rotational speed of the compressor 2 based on the temperature of the heat absorber 9 or the above-mentioned high pressure of the refrigerant circuit R. At this time, the controller 32 selects a smaller compressor target rotational speed from the compressor target rotational speeds obtained by calculations from the temperature of the heat absorber 9 or the high pressure to control the compressor 2.

[0047] It should be noted that even in this internal circulation mode, the gas injection through the injection circuit 40 is not performed, and thus the injection expansion valve 30 is shut off (the shut-off position). (4) Refrigerant flow of a dehumidifying and cooling mode

[0048] Next, in the dehumidifying and cooling mode, the controller 32 opens the solenoid valve 17 and closes the solenoid valve 21, the solenoid valve 22, and the solenoid valve 20. Furthermore, the compressor 2 and the respective fans 15 and 27 are operated, and the air mix damper 28 is in the state where the air blown by the indoor fan 27 is passed through the radiator 4. Consequently, the high-temperature, high-pressure refrigerant gas discharged from the compressor 2 flows into the radiator 4 through the discharge-side heat exchanger 35. The air in the airflow passage 3 is passed through the radiator 4, and thus, the air is heated by the high-temperature refrigerant in the radiator 4 in the airflow passage 3, whereas the refrigerant in the radiator 4 is extracted from the heat by the air and cooled to condense and liquefy.

[0049] The refrigerant flowing out from the radiator 4 flows through the refrigerant 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 be open, to flow into the outdoor heat exchanger 7. The refrigerant flowing into the outdoor heat exchanger 7 is cooled therein by the driving or the outside air passed through the outdoor fan 15 to condense. The refrigerant flowing out from the outdoor heat exchanger 7 flows from the refrigerant pipe 13A through the solenoid valve 17 to subsequently flow into the liquid receiver dryer section 14 and the subcooling section 16. Here, the refrigerant is subcooled.

[0050] The refrigerant flowing out from 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 internal heat exchanger 19 to reach the indoor expansion valve 8. The refrigerant is decompressed in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. The water in the air blown out by 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.

[0051] The refrigerant evaporated in the heat absorber 9 flows through the evaporation ability control valve 11, the internal heat exchanger 19, and the refrigerant pipe 13C to reach the accumulator 12, and flows therethrough to be sucked into the compressor 2, repeating this cycle. The air cooled and dehumidified in the heat absorber 9 is reheated in the process of passing through the radiator 4 (a radiant ability is lower than that during heating), and thus dehumidification and cooling are performed in the vehicle interior.

[0052] The controller 32 controls the rotation speed of the compressor 2 based on the temperature of the heat absorber 9 detected by the heat absorber temperature sensor 48, also controls the valve position of the outdoor expansion valve 6 based on the above-mentioned high pressure of the refrigerant circuit R, and controls a refrigerant pressure of the radiator 4 (a radiator pressure Pci). Note that gas injection by the injection circuit 40 is not performed even in this dehumidification and cooling mode, and thus the injection expansion valve 30 is shut off (the shutoff position). (5) Refrigerant flow of a cooling mode

[0053] In the above state of the dehumidification and cooling mode, the controller 32 next opens the solenoid valve 20 in the cooling mode (in this case, the outdoor expansion valve 6 can have any valve position including a fully open position (the valve position is set to an upper control limit), and the air mix damper 28 has a state where the air is not passed through the radiator 4). Consequently, the high-temperature, high-pressure refrigerant gas discharged from the compressor 2 flows into the radiator 4 through the discharge-side heat exchanger 35. The air in the airflow passage 3 is not passed through the radiator 4, so the refrigerant only passes through here, and the refrigerant flowing out from the radiator 4 flows through the refrigerant pipe 13E to reach the solenoid valve 20 and the outdoor expansion valve 6.

[0054] At this time, the solenoid valve 20 is opened, and thus the refrigerant bypasses the outdoor expansion valve 6 to pass through the bypass pipe 13J and flows as it is into the outdoor heat exchanger 7, where the refrigerant is cooled by the vehicle or the outside air passed through the outdoor fan 15 to condense and liquefy. The refrigerant flowing out of the outdoor heat exchanger 7 flows from the refrigerant pipe 13A through the solenoid valve 17 to subsequently flow into the liquid receiver with dryer section 14 and the subcooling section 16. Here, the refrigerant is subcooled.

[0055] The refrigerant flowing out from 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 internal heat exchanger 19 to reach the indoor expansion valve 8. The refrigerant is decompressed in the indoor expansion valve 8 and then flows into the heat absorber 9 to evaporate. The water in the air blown out by the indoor fan 27 coagulates to adhere to the heat absorber 9 through the heat absorption operation at this time, so that the air is cooled.

[0056] The refrigerant evaporated in the heat absorber 9 flows through the evaporability control valve 11, the internal heat exchanger 19, and the refrigerant pipe 13C to reach the accumulator 12, and flows therethrough to be sucked into the compressor 2, repeating this cycle. The air cooled and dehumidified in the heat absorber 9 does not pass through the radiator 4 but is blown into the vehicle interior from the outlet 29, thus performing cooling in the vehicle interior. In this cooling mode, the controller 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. Note that gas injection by the injection circuit 40 is not performed even in this cooling mode, and thus the injection expansion valve 30 is shut off (the shutoff position). (6) Change control of operating modes

[0057] During startup, the controller 32 selects the operation mode based on an outside air temperature Tam detected by the outside air temperature sensor 33 and a target outlet temperature TAO. In addition, after startup, the controller selects and changes the above respective operation modes in accordance with a change in an environment or setting conditions, such as the outside air temperature Tam, the target outlet temperature TAO, or the like.Basically, in this case, the controller 32 switches from the heating mode to the dehumidification and heating mode, or from the dehumidification and heating mode to the heating mode, switches from the dehumidification and heating mode to the dehumidification and cooling mode, or from the dehumidification and cooling mode to the dehumidification and heating mode, and switches from the dehumidification and cooling mode to the cooling mode, or from the cooling mode to the dehumidification and cooling mode, but when the controller switches from the dehumidification and heating mode to the dehumidification and cooling mode, and switches from the dehumidification and cooling mode to the dehumidification and heating mode, the controller switches via the internal circulation mode.In addition, the control device could switch from the cooling mode to the internal circulation mode or from the internal circulation mode to the cooling mode. (7) Gas injection in a heating mode

[0058] Next, the gas injection in the heating mode above is described. Fig. 3 shows a Ph diagram of the vehicle air conditioner 1 of the present invention in the heating mode. The refrigerant flowing out from the radiator 4 to enter the refrigerant pipe 13E and then distributed to flow into the refrigerant pipe 13K of the injection circuit 40 is decompressed by the injection expansion valve 30, enters the discharge-side heat exchanger 35 to perform heat exchange therein with the refrigerant discharged from the compressor 2 (the refrigerant discharged from the compressor 2 before flowing into the radiator 4), and then absorbs heat to evaporate. After that, the evaporated refrigerant gas returns to the center of compression by the compressor 2, is further compressed together with the refrigerant sucked from the accumulator 12 to be compressed, and is then discharged from the compressor 2 to the refrigerant pipe 13G again.

[0059] In Fig. In FIG. 3, a line labeled 13K shows the refrigerant returned to the compressor 2 through the injection circuit 40. The refrigerant is returned from the injection circuit 40 to the center of compression by the compressor 2, the amount of refrigerant to be discharged from the compressor 2 increases, and thus the heating capability in the radiator 4 improves. However, liquid compression is performed when liquid refrigerant returns to the compressor 2, and thus the refrigerant to be returned from the injection circuit 40 to the compressor 2 must be a gas.

[0060] Therefore, the controller 32 monitors a superheat degree of the refrigerant flowing through the compressor 2 to the midpoint of compression from the pressure and temperature of the refrigerant after the discharge-side heat exchanger 35, which are respectively detected by the injection pressure sensor 50 and the injection temperature sensor 55, and controls the valve position of the injection expansion valve 30 so as to assign a predetermined superheat degree in the heat exchange with the discharged refrigerant. However, in the embodiment, the heat exchange between the refrigerant discharged from the compressor 2 at a remarkably high temperature before flowing into the radiator 4 and the refrigerant flowing through the injection circuit 40 is performed in the discharge-side heat exchanger 35, and thus, a large amount of heat exchange can be achieved.Therefore, the refrigerant in the discharge-side heat exchanger 35 can sufficiently evaporate and a necessary superheat degree can be obtained even if the valve position of the injection expansion valve 30 is increased to increase an injection amount.

[0061] Consequently, the gas injection amount to the compressor 2 can be sufficiently obtained, and the amount of refrigerant to be discharged from the compressor 2 can be increased to improve the heating ability, compared with a case where, as in a conventional technology, the heat exchange is performed between the refrigerant after the radiator and the injection refrigerant.

[0062] Next, a control of a target radiator subcooling degree, which is a target value of a subcooling degree SC of the refrigerant in the compressor 2, the injection circuit 40 and the radiator 4 in the above heating mode, will be described with reference to Fig. 4 to Fig. 10 described. (8) Compressor control in a heating mode

[0063] Fig. 4 shows a control block diagram of the compressor 2, the outdoor expansion valve 6, and the injection expansion valve 30 by the controller 32 in the above heating mode. The controller 32 inputs the target outlet temperature TAO to a target radiator temperature calculation section 57, a target radiator subcooling degree calculation section 58, and a target injection refrigerant superheating degree calculation section 59. The target outlet temperature TAO is a target value of a temperature of air blown from the outlet 29 into the vehicle interior and is calculated from the following equation (I) by the controller 32. TAO=(Tset−Tin)×K+Tbal(f(Tset, SUN, Tam)) where Tset is a set temperature in the vehicle interior set by the air conditioning operating section 53, Tin is a temperature of the air in the vehicle interior detected by the interior air temperature sensor 37, K is a coefficient, and Tbal is a compensation value calculated from the set temperature Tset, a solar radiation amount SUN detected by the solar radiation sensor 51, and an outside air temperature Tam detected by the outside air temperature sensor 33. Furthermore, the lower the outside air temperature Tam, the higher the target outlet temperature TAO generally becomes, and the higher the outside air temperature Tam, the lower it becomes, as shown in Fig. 5, the target outlet temperature.

[0064] The target radiator temperature calculation section 57 of the controller 32 calculates a target radiator temperature TCO from the target outlet temperature TAO, and next, a target radiator pressure calculation section 61 of the controller 32 calculates a target radiator pressure PCO based on the target radiator temperature TCO. Further, a compressor speed calculation section 62 of the controller 32 calculates a target compressor speed TGNCh of the compressor 2 in the heating mode based on the target radiator pressure PCO and a pressure (a radiator pressure) Pci of the radiator 4, which is the high pressure of the refrigerant circuit R detected by the radiator pressure sensor 47, and operates the compressor 2 at the target compressor speed TGNCh.

[0065] Fig. 6 is a control block diagram of the compressor speed calculation section 62. The compressor speed calculation section 62 is composed of an F / F (forward) operation amount calculation section 71, an F / B (feedback) operation amount calculation section 72, an adder 73, and a limit setting section 74. The values calculated by the target radiator temperature calculation section 57 of Fig. 4 The calculated target radiator temperature TCO is input to the target radiator pressure calculation section 61 and the F / F operation amount calculation section 71. As described above, the target radiator pressure calculation section 61 calculates the target radiator pressure PCO, and the calculated target radiator pressure PCO is input to the F / F operation amount calculation section 71 and the F / B operation amount calculation section 72 of the compressor speed calculation section 62.

[0066] The F / F operation amount calculation section 71 calculates an F / F operation amount TGNChff of a target compressor speed based on the outside air temperature Tam obtained from the outside air temperature sensor 33, a blower voltage BLV of the indoor blower 27, an air mix damper opening SW of the air mix damper 28 obtained by SW = (TAO-Te) / (TH-Te), and the target radiator pressure PCO.

[0067] Note that TH is a temperature of the radiator 4 (the radiator temperature) that can be obtained from the radiator temperature sensor 46, and Te is a temperature of the heat absorber 9 (the heat absorber temperature) that can be obtained from the heat absorber temperature sensor 48. In addition, the air mix damper opening SW changes in a range of 0 ≤ SW ≤ 1, an air mix shut-off state in which the air is not passed through the radiator 4 is obtained at 0, and a fully open air mix state in which all the air in the airflow passage 3 is passed through the radiator 4 is obtained at 1.

[0068] The F / B operation amount calculation section 72 calculates an F / B operation amount TGNChfb of the target compressor speed based on the target radiator pressure PCO and the radiator pressure Pci. Further, the F / F operation amount TGNChff calculated by the F / F operation amount calculation section 71 and the F / B operation amount TGNChfb calculated by the F / B operation amount calculation section 72 are added by the adder 73, limits of an upper control limit value (ECNpdLimHi) and a lower control limit value (ECNpdLimLo) are added by the limit setting section 74, and then the target compressor speed TGNCh is determined. In the heating mode (including the dehumidification and heating modes), the controller 32 controls the speed of the compressor 2 based on the target compressor speed TGNCh.

[0069] That is, the target compressor speed TGNCh of the compressor in the heating mode (including the dehumidifying and heating modes) in which the refrigerant in the radiator 4 radiates heat to heat the vehicle interior is determined based on the target radiator pressure PCO (the target high pressure). (9) Gas injection control

[0070] In addition, the target injection refrigerant superheat degree calculation section 59 of Fig. 4, the controller 32 calculates a target value (a target injection refrigerant superheat degree TGSH) of the superheat degree of the injection refrigerant to be returned from the injection circuit 40 to the center of compression by the compressor 2 based on the target outlet temperature TAO. On the other hand, an injection refrigerant superheat degree calculating section 66 of the controller 32 calculates an injection refrigerant superheat degree INJSH of the injection refrigerant based on a pressure (an injection refrigerant pressure Pinj) of the injection refrigerant detected by the injection pressure sensor 50 and a temperature of the injection refrigerant (an injection refrigerant temperature Tinj) detected by the injection temperature sensor 55.

[0071] Further, a target injection expansion valve position calculation section 67 calculates a target valve position of the injection expansion valve 30 (a target injection expansion valve position TGINJCV) based on the injection refrigerant superheat degree INJSH and the target injection refrigerant superheat degree TGSH. Further, the controller 32 controls the valve position of the injection expansion valve 30 to the target injection expansion valve position TGINJCV.

[0072] The target injection refrigerant superheat degree calculation section 59 decreases the target injection refrigerant superheat degree TGSH, for example, as the target outlet temperature TAO increases (a hysteresis is present). When the target injection refrigerant superheat degree TGSH decreases, it means that the valve position of the injection expansion valve 30 is increased to increase the injection amount. That is, the higher the target outlet temperature TAO, the more the controller 32 increases the injection amount to be returned to the compressor 2 through the injection expansion valve 30 and increases the amount of refrigerant to be discharged from the compressor 2 to increase the heating capability.

[0073] In addition, the controller 32 uses equation (II), equation (III), and equation (IV) to calculate a target heating capability (a required heating capability) TGQ, which is a required heating capability of the radiator 4, an estimated maximum HP heating capability value QmaxHP that can be generated by the radiator 4 when the refrigerant is not passed through the injection circuit 40, that is, when the gas injection is not performed, and an estimated maximum INJ heating capability value QmaxINJ that can be generated by the radiator 4 when the refrigerant is passed through the injection circuit 40, that is, when the gas injection is performed. TGQ=(TCO−Te)×Cpa×ρ×Qair QmaxHP=f1(Tam, Nc, BLV, VSP, Te) and QmaxINJ=f2(Tam, Nc, BLV, VSP, Te) where Te is the temperature of the heat absorber 9 detected by the heat absorber temperature sensor 48, Cpa is the specific heat [kj / kg K] of the air flowing into the radiator 4, ρ is a density (a specific volume) [kg / m 3 ] of the air flowing into the radiator 4, Qair is a volume [m 3 / h] of the air passing through the radiator 4 (the passing air volume Qair is estimated from the blower voltage BLV of the interior blower 27 or the like), and VSP is the vehicle speed obtained from the speed sensor 52.

[0074] Note that the temperature of the air flowing into the radiator 4 or the temperature of the air flowing out of the radiator 4 can be used in equation (II) instead of or in addition to Qair. Furthermore, the rotational speed Nc of the compressor 2 of equations (III) and (IV) is an example of an index indicating a refrigerant flow rate, the fan voltage BLV is an example of an index indicating an air volume in the airflow passage 3, and the estimated values of the heating ability QmaxHP and QmaxINJ are calculated from a function of these indexes. In addition, the values can be calculated from these indexes and one of an outlet refrigerant pressure of the radiator 4, an outlet refrigerant temperature of the radiator 4, an inlet refrigerant pressure of the radiator 4, and an inlet refrigerant temperature of the radiator 4, or any combination thereof.

[0075] Further, the controller 32 performs no-injection control when the target heating capacity TGQ is the estimated maximum HP heating capacity value QmaxHP or less. In this case, the controller 32 shuts off the injection expansion valve 30 (the shutoff position) and does not pass the refrigerant through the injection circuit 40. On the other hand, the injection control is performed, and gas injection is performed when the target heating capacity TGQ exceeds the estimated maximum HP heating capacity value QmaxHP, that is, when the estimated maximum HP heating capacity value QmaxHP through the radiator 4 becomes close to the target heating capacity TGQ. In this case, the controller 32 defines the valve position of the injection expansion valve 30 as a predetermined value to open the valve and performs gas injection to the compressor 2.That is, as described above, the controller 32 controls the valve position of the injection expansion valve 30 to the target injection expansion valve position TGINJCV. (10) Target radiator subcooling level control

[0076] Furthermore, the target radiator subcooling degree calculation section 58 of the controller 32 calculates a target radiator subcooling degree TGSC of the radiator 4 based on the target outlet temperature TAO. The target radiator subcooling degree calculation section 58 will be described in detail later. On the other hand, a radiator subcooling degree calculation section 63 of the controller 32 calculates the subcooling degree (the radiator subcooling degree SC) of the refrigerant in the radiator 4 based on the radiator pressure Pci and a temperature of the radiator 4 (a radiator temperature Tci) detected by the radiator temperature sensor 46. Further, a target outdoor expansion valve position calculation section 64 calculates a target valve position of the outdoor expansion valve 6 (a target outdoor expansion valve position TGECCV) based on the radiator subcooling degree SC and the target radiator subcooling degree TGSC.Furthermore, the control device 32 controls the valve position of the outdoor expansion valve 6 to the target outdoor expansion valve position TGECCV.

[0077] Next, with reference to Fig. 7 to Fig. 11 a structure and an operation of the target radiator subcooling degree calculation section 58 of Fig. 4. As described in Fig. As shown in Fig. 7, the target radiator subcooling degree calculation section 58 is composed of a target SC base value calculation section 76, a target radiator subcooling degree correction value calculation section 77, a correction permission / prohibition switching section 78, and an adder 79. The controller 32 has two control states in this heating mode: effectiveness priority control and capability priority control, and switches the state depending on whether a capability priority flag fPRIability is "1" (set) or "0" (reset). The adder 79 adds a target radiator subcooling degree base value TGSCbase calculated by the target SC base value calculating section 76, as described later, and a target radiator subcooling degree correction value TGSChos from the correction permission / prohibition switching section 78.

[0078] In the correction permission / prohibition switching section 78, the target radiator subcooling degree correction value TGSChos calculated by the target radiator subcooling degree correction value calculation section 77, as described later, and "0" are input. Moreover, when the above-mentioned capability priority flag fPRIability is "1" (set), the target radiator subcooling degree correction value TGSChos calculated by the target radiator subcooling degree correction value calculation section 77 is output from the correction permission / prohibition switching section 78 to the adder 79, and when the capability priority flag fPRIability is "0" (reset), "0" (ordinary control without correction) is output from the correction permission / prohibition switching section 78 to the adder 79.

[0079] That is, in the capability priority control in which the capability priority flag fPRIability is “1” (set), the target radiator subcooling degree correction value TGSChos calculated by the target radiator subcooling degree correction value calculation section 77 is added to the target radiator subcooling degree base value TGSCbase calculated by the target SC base value calculation section 76 to obtain a value of the target radiator subcooling degree TGSC (TGSC = TGSCbase + TGSChos), and in the efficiency priority control in which the capability priority flag fPRIability is “0” (reset), a value obtained by adding the target radiator subcooling degree correction value TGSChos of “0” from the correction permission / prohibition switching section 78 to the value calculated by the target SC base value calculation section 76 Target radiator subcooling degree base value TGSCbase obtained value, ie the target radiator subcooling degree base value TGSCbase, the target radiator subcooling degree TGSC (TGSC = TGSCbase). (10-1) Efficiency priority control

[0080] The above-mentioned controller 32 usually performs efficiency priority control (the capability priority flag fPRIability = "0"). That is, the target SC base value calculation section 76 calculates the target radiator subcooling degree base value TGSCbase based on the outside air temperature Tam obtained from the outside air temperature sensor 33, the fan voltage BLV of the indoor fan 27, and the air mix damper opening SW of the air mix damper 28, which is obtained by SW = (TAO-Te) / (TH-Te). At this time, the volume Qair [m 3 / h] of the air to be passed through the radiator 4, as described above, is also estimated from the blower voltage BLV of the interior blower 27 or the like.

[0081] Here, when the heating capacity is constant, the radiator subcooling degree SC at which an operating efficiency COP is maximized is present. In the case of efficiency priority control, the target SC base value calculation section 76 aims at a point where COP is maximized for the purpose of prioritizing operating efficiency, thereby calculating the target radiator subcooling degree base value TGSCbase. Fig. 8 shows this behavior. In a case where the volume Qair of the air to be passed through the radiator 4 is 100 m 3 / h, the target SC base value calculation section 76 determines that the target radiator subcooling degree base value TGSCbase is 10 (deg) at all the target outlet temperatures TAO, even when the outdoor air temperature Tam is 0°C (L1) or -10°C (L2). Note that when the outdoor air temperature is 0°C or less, the base value is 10 deg.

[0082] In addition, the target SC base value calculation section 76 determines, in a case where the volume Qair of the air to be passed through the radiator 4 is 200 m 3 / h is that, at all the target outlet temperatures TAO from 30 (deg) to 80 (deg), the target radiator subcooling degree base value TGSCbase is 25 (deg) even when the outdoor air temperature Tam is 0°C (L3) or -10°C (L4). However, the calculation section gradually increases the temperature to 30 (deg) in a heating-up region where the target outlet temperature TAO is higher than 80 (deg). Note that when the outdoor air temperature is -10°C or less, the base value is the same as at -10°C. In addition, the target SC base value calculation section 76 determines in a case where the passing air volume Qair is 150 m 3 / h is that the target radiator subcooling degree base value TGSCbase at all the target outlet temperatures TAO is 16.8 (deg, L5).

[0083] Thus, the target SC base value calculation section 76 calculates the target radiator subcooling degree base value TGSCbase based on the volume Qair of air to be passed through the radiator 4 to aim for maximum efficiency. In the efficiency priority control, "0" is input to the adder 79 from the correction permission / prohibition switching section 78, and thus the calculated target radiator subcooling degree base value TGSCbase becomes the target radiator subcooling degree TGSC. Further, as described above, the target outdoor expansion valve position TGECCV of the outdoor expansion valve 6 is calculated based on the target radiator subcooling degree TGSC and the radiator subcooling degree SC calculated by the radiator subcooling degree calculating section 63, and the valve position of the outdoor expansion valve 6 is controlled to this calculated target outdoor expansion valve position TGECCV. (10-2) Skill Priority Control

[0084] Next, the above-mentioned capability priority control will be described. As described above, the controller 32 usually executes efficiency priority control, but when the capability priority flag fPRIability is "1" (set), the controller switches to capability priority control. (10-2-1) Setting / resetting a capability priority flag fPRIability

[0085] Next, switching between efficiency priority control and capability priority control will be described. In the case of the above-mentioned control without injection by the injection circuit 40, if all conditions (capability priority prerequisite conditions) mentioned below are met and the capability priority flag fPRIability = "1" (set), the controller first switches to capability priority control. That is, the following state continues for a predetermined time or longer: • TGQ > QmaxHP (e.g. 4 kW); • (TGNCmax-NC) ≥ ΔN1 (e.g. 100 min -1 ); • Tam < A1 (e.g. -10°C); and • (TCO-TH) ≥ ΔT1 (e.g. 5 deg).

[0086] It should be noted that TGNCmax is a target compressor speed upper limit, ECNpdLimHi mentioned above, and NC is the upper limit of a control speed of compressor 2.

[0087] In the case of the above-mentioned injection control, the above conditions are additionally verified as follows. That is, the following state continues for a predetermined time or longer: • TGQ > QmaxINJ (e.g. 5 kW); • (TGNCmax-NC) ≥ ΔN2 (e.g. 100 min -1 ); • Tam < A2 (e.g. -15°C); and • (TCO-TH) ≥ ΔT1 (e.g. 5 deg).

[0088] That is, when the heating ability by the radiator 4 becomes scarce, the target heating ability TGQ is larger than the estimated maximum HP heating ability value QmaxHP or the estimated maximum INJ heating ability value QmaxINJ, and the rotational speed of the compressor 2 is still lower than the upper control limit, the controller 32 sets the ability priority flag fPRIability to "1", and switches to the ability priority control under the conditions that there is a state where the outside air temperature Tam is low and the radiator temperature TH is also as much as a predetermined value or more lower than the target radiator temperature TCO.

[0089] Furthermore, as described above, in the case of control without injection and with injection, the heating capability of the radiator 4 varies, and the estimated maximum INJ heating capability value QmaxINJ is also larger than the estimated maximum HP heating capability value QmaxHP. Therefore, switching conditions are changed, and the outside air temperature Tam is set at a lower value. Note that in the case of control with injection, the target heating capability is large, and thus the capability priority flag fPRIability can be set unconditionally.

[0090] Next, the conditions for resetting the capability priority flag fPRIability to "0" are as follows. That is, during the non-injection control, all of the following conditions (capability priority cancellation conditions) mentioned below are detected, and after a predetermined time has elapsed, the capability priority flag fPRIability is reset to "0," and the capability priority control is canceled to switch to the efficiency priority control. That is, • TGQ < QmaxHP (e.g. 4 kW)-0.5 kW; (TCO-TH) < ΔT2 (e.g. 2 deg); and • TGSChos < SC (e.g. 3 deg).

[0091] In addition, conditions for control with injection are as follows: • TGQ < QmaxINJ (e.g. 5 kW)-0.5 kW; (TCO-TH) < ΔT2 (e.g. 2 deg); and • TGSChos < SC (e.g. 3 deg).

[0092] That is, the shortage of heating capability by the radiator 4 is eliminated, the estimated maximum HP heating capability value QmaxHP or the estimated maximum INJ heating capability value QmaxINJ is greater than the target heating capability TGQ, a difference between the radiator temperature TH and the target radiator temperature TCO is reduced to be smaller than a predetermined value, and the target radiator subcooling degree correction value TGSChos decreases. Assuming that the above state continues, the controller 32 resets the capability priority flag fPRIability to "0" and cancels the capability priority control to return to the efficiency priority control. (10-2-2) Target radiator subcooling degree correction value calculation

[0093] Next, the calculation of the target radiator subcooling degree correction value TGSChos in the target radiator subcooling degree correction value calculation section 77 will be described. The target compressor speed upper limit TGNCmax (the upper control limit of the speed of compressor 2), the speed NC of compressor 2, the target radiator pressure PCO (the target high pressure value), and the radiator pressure Pci are input to the target radiator subcooling degree correction value calculation section 77.

[0094] Fig. 9 shows a control block diagram of the target radiator subcooling degree correction value calculation section 77. In this capability priority control, the controller 32 has a high pressure priority mode and a speed priority mode, and switches and executes these two modes, but a subtractor 81, a dead zone processing section 82, and an amplifier 83 constitute Fig. 9 constitutes an execution block of the speed priority mode, and a subtractor 84, a dead zone processing section 86, and an amplifier 87 constitute an execution block of the high pressure priority mode.

[0095] Outputs of the respective amplifiers 83 and 87 are input to a priority mode switching section 88, and these modes are switched by setting a priority mode flag fTGSCNCfb to "1" and resetting the flag to "0" to be output to an adder 91. The foregoing value is added by the adder 91, a limit setting section 89 establishes limits of an upper control limit value (TGSChosHi) and a lower control limit value (TGSChosLo), and then the target radiator subcooling degree correction value TGSChos is determined.

[0096] That is, the upper limit target compressor speed TGNCmax (the upper control limit of the speed of the compressor 2) in the speed priority mode is input as a minus (-), and the speed NC of the compressor 2 is input as a plus (+) into the subtractor 81, and its deviation e is calculated by the dead zone processing section 82 (for example, 100 min -1a dead zone) and amplified by the amplifier 83 to be input to the priority mode switching section 88. That is, feedback control (I component) of the target compressor speed upper limit value TGNCmax to the speed NC is performed. An output value of the amplifier 83 is the target radiator subcooling degree correction value TGSChos for decreasing the radiator subcooling degree SC in a direction of increasing the speed NC of the compressor 2, with the speed NC of the compressor 2 finally being set to the target compressor speed upper limit value (the control upper limit value) TGNCmax.Consequently, in this speed priority mode, the target radiator subcooling degree correction value TGSChos is calculated based on the deviation e between the target compressor speed upper limit (the control upper limit) TGNCmax and the actual speed NC of the compressor 2, and feedback correction of the target radiator subcooling degree TGSC is performed.

[0097] Furthermore, in the high-pressure priority mode, the radiator pressure Pci is input as a minus (-) and the target radiator pressure PCO (the target value of the high pressure) as a plus (+) to the subtractor 84, and their deviation e is supplied through the dead zone processing section 86 (for example, 0.05 MPa is a dead zone) and amplified by the amplifier 87 to be input to the priority mode switching section 88. That is, feedback control (I component) of the radiator pressure Pci to the target radiator pressure PCO is performed. An output value of the amplifier 87 is the target radiator subcooling degree correction value TGSChos to increase the radiator subcooling degree SC in a direction in which the radiator pressure Pci (the high pressure) is increased, the radiator pressure Pci (the high pressure) being finally set to a control upper limit value PCOmax of the target radiator pressure PCO.Consequently, in this high pressure priority mode, the target radiator subcooling degree correction value TGSChos is calculated based on the deviation e between the upper control limit value PCOmax of the target radiator pressure PCO (the target value of the high pressure) and the actual radiator pressure (the high pressure) Pci, and the feedback correction of the target radiator subcooling degree TGSC is performed. (10-2-3) High pressure priority mode and speed priority mode switching conditions

[0098] As described above, the high-pressure priority mode and the speed priority mode are switched by setting the priority mode flag fTGSCNCfb to "1" and resetting the flag to "0." The controller 32 sets the priority mode flag fTGSCNCfb to a reset "0" state until the radiator pressure Pci reaches the control upper limit PCOmax, and sets the flag to "1" when the pressure reaches PCOmax. Thereafter, the priority mode flag fTGSCNCfb is reset to "0" when the radiator pressure Pci decreases by a predetermined hysteresis (e.g., 0.1 MPa or the like). (11) Actual radiator subcooling degree SC control operation

[0099] Circumstances of the above-mentioned switching of the efficiency priority control and the capability priority control, and the switching of the priority mode will be explained with reference to Fig. 10 and Fig. 11. In step S1 of Fig. 10, the controller 32 reads all the data (temperature data and pressure data), and in step S2, the controller decides whether the heating mode is currently established. In the case of the heating mode, the controller 32 proceeds from step S2 to step S3, and the target SC base value calculation section 76 calculates the target radiator subcooling degree base value TGSCbase as described above. Next, in step S4, the controller calculates the target heating capability (a required heating capability) TGQ, the estimated maximum HP heating capability value QmaxHP, and the estimated maximum INJ heating capability value QmaxINJ, and in step S5, the controller judges whether or not all the conditions for the capability priority flag fPRIability = "1" (set) are met.

[0100] Further, in a case where all the conditions are not satisfied in step S6, it is judged that the capability priority control is not required, the capability priority flag fPRIability is reset to “0”, and the controller goes to step S9, in which the target radiator subcooling degree correction value TGSChos = 0. In this case, the efficiency priority control is executed, and the target radiator subcooling degree base value TGSCbase becomes the target radiator subcooling degree TGSC.

[0101] While such efficiency priority control is being executed, the control device 32 receives, in a case where, for example, due to a drop in the outside air temperature or the like, as shown in Fig. 11, the estimated maximum HP heating capability value QmaxHP is below the target heating capability TGQ, and all the conditions (the capability priority prerequisite conditions) for the capability priority flag fPRIability = "1" (set) are satisfied, in the step S6, the control system sets the capability priority flag fPRIability = "1" (set) and proceeds to step S7, executing the above-mentioned capability priority control.

[0102] When the controller switches to this capability priority control, the radiator pressure Pci (the high pressure) is lower than the upper control limit value PCOmax of the target radiator pressure PCO, and thus the controller 32 sets the priority mode switching flag fTGSCNCfb to "0" to execute the high pressure priority mode. In this high pressure priority mode, as described above, the target radiator subcooling degree correction value TGSChos is a value to decrease the target radiator subcooling degree TGSC, and thus, as shown in Fig. 11, the radiator subcooling degree SC increases, and the radiator pressure Pci (the high pressure) increases to the upper control limit PCOmax.

[0103] In a case where the radiator pressure Pci (the high pressure) rises to the upper control limit PCOmax, the controller 32 sets the priority mode switching flag fTGSCNCfb to "1," and thus the controller switches to the speed priority mode at this time. In this speed priority mode, as described above, the target radiator subcooling degree correction value TGSChos is a value for lowering the target radiator subcooling degree TGSC, and thus, as shown in Fig. 11, the radiator subcooling degree SC. As the radiator subcooling degree SC decreases, the radiator pressure Pci also decreases, and thus the controller 32 increases the rotational speed NC of the compressor 2 up to the upper control limit value TGNCmax of a target compressor rotational speed TGNCh. Consequently, the refrigerant flow rate increases.

[0104] When the radiator pressure Pci (the high pressure) decreases as much as a hysteresis of 0.1 MPa, the controller 32 resets the priority mode switching flag fTGSCNCfb to "0" in this state, and thus the priority mode returns to the high pressure priority mode.

[0105] While such capability priority control is being executed, in a case where the outside air temperature rises and all the conditions (the capability priority cancellation conditions) for the above-mentioned capability priority flag fPRIability = "0" (reset) are established, the controller 32 decides the capability priority flag fPRIability = "0" (reset) in step S8 and returns to the efficiency priority control. (12) Another example of a correction control of a target radiator subcooling degree

[0106] Next, Fig. 12 shows another example of correction control of the target radiator subcooling degree TGSC of the radiator 4. In this case, the controller 32 determines, on the basis of a data table, the target radiator subcooling degree correction value TGSChos between an upper correction limit value HOSHi (e.g., 15 deg) and a lower correction limit value HOSLo (0 deg) in which a hysteresis of approximately 0.4 MPa is set.

[0107] That is, in this embodiment, the controller 32 first calculates the target radiator subcooling degree correction value TGSChos in accordance with the table of Fig. 12 as the upper correction limit value HOSHi to execute the high pressure priority mode in which the radiator pressure Pci (the high pressure) is increased. Further, in a case where the radiator pressure Pci (the high pressure) comes close to the upper control limit value PCOmax of the target radiator pressure PCO, the speed priority mode is executed to gradually decrease the target radiator subcooling degree correction value TGSChos from the upper correction limit value HOSHi to the lower correction limit value HOSLo. In contrast, when the radiator pressure Pci decreases and moves away from the upper control limit value PCOmax, the correction value is gradually increased again to the upper correction limit value HOSHi in the high pressure priority mode.

[0108] As described in detail above, the controller 32 in the present invention has the high pressure priority mode for increasing the target radiator subcooling degree TGSC of the radiator 4 in a direction in which the high pressure (the radiator pressure Pci) is set to a predetermined high value (the upper control limit value PCOmax of the target radiator pressure PCO in the embodiment), and the speed priority mode for decreasing the target subcooling degree TGSC of the radiator 4 in a direction in which the rotational speed NC of the compressor 2 is set to a predetermined high value (the upper control limit value TGNCmax of the target compressor rotational speed, which is the upper control limit value in the embodiment), and switches and executes the high pressure priority mode and the speed priority mode, thereby changing the target radiator subcooling degree TGSC of the radiator 4 so that the rotational speed NC of the compressor 2 is maintained to be high.while maintaining the high pressure (the radiator pressure Pci) at the predetermined high value (approximately the upper control limit PCOmax of the target radiator pressure PCO). Consequently, the refrigerant flow rate is also achieved while maintaining the high pressure during heating, making it possible to achieve an improvement in heating capability.

[0109] In this case, the controller executes the high pressure priority mode to increase the target radiator subcooling degree TGSC of the radiator 4 in the direction in which the high pressure (the radiator pressure Pci) is set to the predetermined high value (the control upper limit PCOmax of the target radiator pressure PCO), switches to the speed priority mode in a case where the high pressure (the radiator pressure Pci) reaches the predetermined high value (the control upper limit PCOmax), and decreases the target radiator subcooling degree TGSC of the radiator 4 in the direction in which the rotational speed NC of the compressor 2 is set to the predetermined high value (the target compressor rotational speed upper limit TGNCmax), so that the radiator subcooling degree SC satisfying both the high pressure and the refrigerant flow rate can be appropriately controlled.

[0110] Specifically, in the high-pressure priority mode, the target radiator subcooling degree TGSC of the radiator 4 is increased in the direction in which the high pressure (the radiator pressure Pci) is set to the control upper limit PCOmax, and in the speed priority mode, the target radiator subcooling degree TGSC of the radiator 4 is decreased in the direction in which the rotational speed NC of the compressor 2 is set to the target compressor rotational speed upper limit TGNCmax (the control upper limit). Consequently, the rotational speed NC of the compressor 2 is increased to also maintain the refrigerant flow rate, while the radiator subcooling degree SC is appropriately controlled to suppress the high pressure to the control upper limit PCOmax or less, so that the heating capability can be improved.

[0111] According to the embodiment, in this case, in the high pressure priority mode, the feedback correction of the target radiator subcooling degree TGSC of the radiator 4 is performed based on the deviation e between the high pressure control upper limit value PCOmax (the radiator pressure Pci) and the actual high pressure (the radiator pressure Pci), and in the speed priority mode, the feedback correction of the target radiator subcooling degree TGSC of the radiator 4 is performed based on the deviation e between the target compressor speed upper limit value (the control upper limit value) TGNCmax of the speed NC of the compressor 2 and the actual speed NC, so that it is possible to always stably realize the correction of the radiator subcooling degree SC.

[0112] In addition, the controller 32 has the efficiency priority control and the capability priority control, determines the target radiator subcooling degree TGSC of the radiator 4 based on the volume of air to be passed through the radiator 4 in the efficiency priority control, switches to the capability priority control in the case where the conditions arise in which the heating ability by the radiator 4 becomes scarce, executes the high-pressure priority mode and the speed priority mode in this capability priority control, and corrects the target radiator subcooling degree TGSC of the radiator 4. Therefore, the controller always executes the efficiency priority control and can execute the capability priority control to execute the high-pressure priority mode and the speed priority mode only in the case where the heating ability of the radiator 4 becomes scarce.

[0113] Consequently, as in the lowest level of Fig.11, it is possible to achieve the improvement in heating ability while minimizing deterioration in operation efficiency, and thus the present invention is remarkably suitable in a vehicle such as the electric car or the hybrid car that drives the compressor 2 with the energy stored in the battery.

[0114] Moreover, the controller 32 changes the capability priority prerequisite conditions to switch to the capability priority control in a case where a part of the refrigerant flowing out from the radiator 4 is returned to the compressor 2 through the injection circuit 40 and a case where the part of the refrigerant is not returned to the compressor, and thus it is possible to sufficiently perform the correction of the radiator subcooling degree SC in consideration of the improvement of the heating capability due to increasing the amount of the refrigerant discharged from the compressor 2 by the gas injection.

[0115] It should be noted that the invention present in the embodiment is applied to the vehicle air conditioner 1 that changes and executes the respective operation modes of the heating mode, the dehumidifying and heating mode, the dehumidifying and cooling mode, and the cooling mode, but the present invention is not limited to this embodiment, and the present invention is also effective to a vehicle air conditioner that executes only the heating mode.

[0116] In addition, the configuration or each numerical value of the refrigerant circuit R described in the above embodiment is not limited to the embodiment, and needless to say, they can be changed without departing from the spirit of the present invention. For example, in the high-pressure priority mode, the predetermined high value does not need to be the control upper limit value PCOmax of the target radiator pressure PCO, and may be a lower predetermined high value. Also, the predetermined high value in the speed priority mode does not need to be the control upper limit value TGNCmax of the target compressor speed TGNCh, and may be a lower predetermined high value. Description of reference symbols 1 vehicle air conditioning system 2 compressor 3 Airflow passage 4 Radiators 6 Outdoor expansion valve 7 outdoor heat exchangers 8 Interior expansion valve 9 heat absorbers 11 Evaporation capacity control valve 17, 20, 21 and 22 solenoid valve 26 intake change valve 27 Interior blower (blower fan) 28 air mixing valve 30 Injection expansion valve 32 Control device (control means) 35 discharge-side heat exchanger 40 injection circuit R Refrigerant circuit

Claims

[1] Vehicle air conditioning system (1), comprising: a compressor (2) which compresses a refrigerant; a radiator (4) which radiates heat from the refrigerant to heat air to be supplied into a vehicle interior; an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat; an expansion valve (6) which decompresses the refrigerant flowing into the outdoor heat exchanger (7); and a control means (32), wherein the control means (32) is configured to allow the refrigerant discharged from the compressor (2) to radiate heat in the radiator (4), to decompress the refrigerant through which heat has been radiated through the expansion valve (6) and then to absorb heat in the outdoor heat exchanger (7), thereby heating the vehicle interior, wherein the control means (32) is configured to control a degree of subcooling (SC) of the refrigerant in the radiator (4) through the expansion valve (6) and to control a rotational speed (NC) of the compressor (2) based on a high pressure (Pci), and a high pressure priority mode to increase a target radiator subcooling degree (TGSC) of the radiator (4) so that the high pressure (Pci) is set to a predetermined high value, and has a speed priority mode to reduce the target radiator subcooling degree (TGSC) of the radiator (4) so that the speed (NC) of the compressor (2) is set to a predetermined high value. [2] The vehicle air conditioner (1) according to claim 1, wherein the control means (32) is configured to switch and execute the high pressure priority mode and the speed priority mode, while changing the target radiator subcooling degree (TGSC) of the radiator (4) to keep the speed (NC) of the compressor (2) high while maintaining the high pressure (Pci) at the predetermined high value. [3] The vehicle air conditioner (1) according to claim 2, wherein the control means (32) is configured to execute the high pressure priority mode to increase the target radiator subcooling degree (TGSC) of the radiator (4) so that the high pressure (Pci) is set to the predetermined high value, to switch to the speed priority mode in a case where the high pressure (Pci) reaches the predetermined high value, and to decrease the target radiator subcooling degree (TGSC) of the radiator (4) so that the speed (NC) of the compressor (2) is set to the predetermined high value. [4] Vehicle air conditioning system (1) according to one of claims 1 to 3, wherein the control means (32) is configured to increase the target radiator subcooling degree (TGSC) of the radiator (4) in the high pressure priority mode so that the high pressure (Pci) is set to an upper control limit value (PCOmax) of a target value of the high pressure, and the control means (32) is configured to reduce the target radiator subcooling degree (TGSC) of the radiator (4) in the speed priority mode so that the speed (NC) of the compressor (2) is set to an upper control limit value (TGNCmax). [5] The vehicle air conditioner (1) according to claim 4, wherein the control means (32) is configured to perform, in the high pressure priority mode, a feedback correction of the target radiator subcooling degree (TGSC) of the radiator (4) based on a deviation between the upper control limit value (PCOmax) of the target high pressure value and the high pressure (Pci), and the control means (32) is configured to perform, in the speed priority mode, the feedback correction of the target radiator subcooling degree (TGSC) of the radiator (4) based on a deviation between the upper control limit value (TGNCmax) of the speed of the compressor (2) and the speed (NC). [6] Vehicle air conditioning system (1) according to one of claims 1 to 5, wherein the control means (32) has an efficiency priority control and a capability priority control, the control means (32) is configured to determine, in the efficiency priority control, the target radiator subcooling degree (TGSC) of the radiator (4) on the basis of a volume (Qair) of air to be passed through the radiator (4), and in a case where conditions arise that a heating capability by the radiator (4) becomes scarce, is configured to switch to the capability priority control, and the control means (32) is configured to execute the high pressure priority mode and the speed priority mode in the capability priority control, and to correct the target radiator subcooling degree (TGSC) of the radiator (4). [7] Vehicle air conditioning system (1) according to claim 6, which has an injection circuit (40) which distributes part of the refrigerant flowing out of the radiator (4) in order to return the part of the refrigerant to the compressor (2), wherein the control means (32) is configured to change conditions to switch to the capability priority control in a case where the injection circuit (40) returns the part of the refrigerant flowing out from the radiator (4) to the compressor (2) and in a case where the injection circuit (40) does not return the part of the refrigerant to the compressor (2).

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