Vehicular air conditioner

Abstract

To seamlessly perform transition between a hot gas heating mode and a heat absorbing / heating mode to improve comfort of an occupant.SOLUTION: A vehicular air conditioner, which comprises a refrigerant circuit and a control device that controls the refrigerant circuit and a heat medium circuit, can execute a heat absorbing / heating mode of making refrigerants absorb heat of an object whose heat is absorbed such as external air in an external heat exchanger and a hot gas heating mode in which some of the refrigerants compressed by a compressor are bypassed and returned to the compressor and the residuals of the refrigerants are radiated to heat a vehicle interior. During execution of the hot gas heating mode, when it is determined that a heating capability in the heat absorbing / heating mode satisfies a target heating capability, the vehicular air conditioner executes a second transition mode in which a heating medium is heated by surplus heat of the refrigerants in the hot gas heating mode, the refrigerants are made to absorb heat from the heat medium after a second decompressing part is closed, and the absorption by the refrigerants of heat from the heat medium is stopped after a first decompressing part is opened, and then transits the mode to the heat absorbing / heating mode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle air conditioner.

Background Art

[0002] In recent years, vehicles such as hybrid vehicles and electric vehicles that drive a driving motor with electric power supplied from a battery have become widespread. As a vehicle air conditioner mounted on such a vehicle, one using a heat pump (refrigerant circuit) as a heat source is known.

[0003] In a vehicle air conditioner using a heat pump, during heating operation, an external heat exchanger disposed outside the vehicle such as an outdoor heat exchanger functions as an absorber to obtain a heating heat source from outside air or the like (absorption heating mode). Therefore, when the outside air temperature becomes extremely low (for example, -20 degrees), it becomes difficult to absorb heat from outside air or the like, and the heating capacity greatly decreases. On the other hand, as effective heating in an extremely low temperature environment, hot gas heating that uses high-temperature and high-pressure refrigerant discharged from a compressor without absorbing heat from outside air or the like is known (hot gas heating mode).

[0004] For example, in the vehicle air conditioner of Patent Document 1, among the high-temperature and high-pressure refrigerant discharged from the compressor, a part is made to flow through a bypass passage, decompressed, and then returned to the compressor, and the rest is heat-exchanged with the air blown into the vehicle interior in the indoor heat exchanger and then decompressed and returned to the compressor without passing through the external heat exchanger, thereby executing the hot gas heating mode.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a vehicle air conditioner as described above, for example, when starting up, the hot gas heating mode may be executed to raise the temperature inside the vehicle as quickly as possible, and after the temperature inside the vehicle reaches the desired temperature, the control may be such that the operation is switched to the heat absorption heating. Also, during the execution of the heat absorption heating mode, when the heating capacity is insufficient, the control may be such that the operation is switched to the hot gas heating mode.

[0007] By the way, in the hot gas heating mode and the heat absorption heating mode, the pressure ranges of the refrigerant for stably continuing the operation of each heating mode are different. For this reason, in the vehicle air conditioner, in order for the pressures on the suction side and the discharge side of the compressor to fall within the pressure ranges suitable for each heating mode, each component device of the refrigerant circuit such as the compressor and the flow path switching valve (including the pressure reducing valve) is controlled according to each heating mode. On the other hand, since the flow paths of the refrigerant in the refrigerant circuit are different between the hot gas heating mode and the heat absorption heating mode, when switching between the heating modes, switching control of a plurality of flow path switching valves is required.

[0008] However, when all the flow path switching valves are immediately switched while the compressor is being driven during the transition between the heating modes, the pressure of the refrigerant fluctuates greatly due to the sudden change in the flow path, deviating from the pressure range suitable for each heating mode, and there is a risk that the operation of the vehicle air conditioner 1 will stop. That is, there is a problem that it is difficult to seamlessly perform the transition between the hot gas heating mode and the heat absorption heating mode while stably continuing the operation of the vehicle air conditioner, and there is a risk of impairing the comfort of the passengers.

[0009] The present invention has been made in view of such circumstances, and an object thereof is to perform a seamless transition between the hot gas heating mode and the heat absorption heating mode and improve the comfort of passengers.

Means for Solving the Problems

[0010] The present invention relates to a vehicle air conditioner including a compressor, an indoor heat exchanger, an outdoor heat exchanger, and a hot gas bypass for decompressing at least a part of the refrigerant compressed by the compressor and returning it to the compressor without passing through the indoor heat exchanger and the outdoor heat exchanger, a refrigerant circuit including the above, a heat medium circuit for circulating a heat medium that exchanges heat with the refrigerant in a refrigerant heat medium heat exchanger provided in the refrigerant circuit, and a control device for controlling the refrigerant circuit and the heat medium circuit. In the refrigerant circuit, the refrigerant circuit includes a first decompression unit for decompressing the refrigerant flowing into the outdoor heat exchanger and a second decompression unit for decompressing the refrigerant flowing through the hot gas bypass. The control device is capable of executing an endothermic heating mode in which the refrigerant absorbs heat in the outdoor heat exchanger and a hot gas heating mode in which a part of the refrigerant compressed by the compressor flows through the hot gas bypass and the remainder flows through the indoor heat exchanger. During the execution of the hot gas heating mode, when it is determined that the heating capacity in the endothermic heating mode satisfies the target heating capacity, a first stage of controlling to dissipate the heat of the surplus refrigerant in the hot gas heating mode in the refrigerant heat medium heat exchanger to heat the heat medium, a second stage of closing the second decompression unit and controlling the refrigerant to absorb heat from the heat medium in the refrigerant heat medium heat exchanger, a third stage of controlling to open the first decompression unit, and a fourth stage of controlling to stop the refrigerant from absorbing heat from the heat medium in the refrigerant heat medium heat exchanger are sequentially performed. After executing a second transition mode, the vehicle air conditioner is provided that transitions to the endothermic heating mode.

Advantages of the Invention

[0011] According to the present invention, seamless transition between the hot gas heating mode and the endothermic heating mode can be performed, and the comfort of passengers can be improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings indicate parts having the same function, and duplicate descriptions in each drawing are omitted as appropriate. In the drawings, the thick black line in the refrigerant circuit 10 indicates the refrigerant flow path through which the high-pressure refrigerant flows, and the double line indicates the refrigerant flow path through which the low-pressure refrigerant after pressure reduction flows. Also, the triple line in the heat medium circuit 30 indicates the heat medium flow path through which the heat medium flows. Furthermore, the broken line in the refrigerant circuit 10 indicates the refrigerant flow path through which the refrigerant does not flow.

[0014] [Configuration of Refrigerant Circuit etc.] FIG. 1 shows a configuration example of a vehicle air conditioner 1 according to an embodiment of the present invention. The configuration example shown here is just an example and is not particularly limited to a specific configuration.

[0015] The vehicle air conditioner 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21 and 22 provided inside the air conditioning unit 20, and an external heat exchanger 11 provided outside the vehicle compartment, and these are arranged along the refrigerant flow path. The indoor heat exchangers 21 and 22 are provided to exchange heat between the air flowing inside the air conditioning unit 20 and led into the vehicle compartment and the refrigerant, and the external heat exchanger 11 is provided to exchange heat between the outside air and the refrigerant outside the vehicle compartment.

[0016] The external heat exchanger 11 is used to absorb heat from the outside air into the refrigerant in the heat absorption heating mode described later to obtain a heat source for heating. A refrigerant pressure sensor 44C for detecting the refrigerant pressure PXO (low-pressure side refrigerant pressure) and a refrigerant temperature sensor 43C for detecting the refrigerant temperature TXO (low-pressure side refrigerant temperature) are provided immediately downstream of the external heat exchanger 11.

[0017] The indoor heat exchanger 21 is used for heating air, and the indoor heat exchanger 22 is used for cooling air. A refrigerant pressure sensor 44B for detecting the outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) and a refrigerant temperature sensor 43B for detecting the outlet refrigerant temperature Tc (high-pressure side refrigerant temperature) are provided immediately downstream of the indoor heat exchanger 21 in the refrigerant circuit 10.

[0018] The compressor 2 compresses the refrigerant and circulates it within the refrigerant circuit 10. The refrigerant compressed by the compressor 2 is decompressed by passing through, for example, a first pressure reducing section V1, a second pressure reducing section V2, a third pressure reducing section V3, and a fourth pressure reducing section V4, which are, for example, expansion valves, in a refrigerant flow path selected as appropriate. In the refrigerant circuit 10, there are provided flow path switching valves 12 and 13 for switching the refrigerant flow path, and check valves 14 and 15 for regulating the flow direction of the refrigerant.

[0019] An accumulator 16 for collecting the liquid refrigerant and separating the refrigerant into gas and liquid is provided immediately upstream of the compressor 2 in the refrigerant circuit 10. Between the accumulator 16 and the compressor 2, there are provided a refrigerant pressure sensor 44A for detecting the suction refrigerant pressure Ps (low-pressure side refrigerant pressure) sucked into the compressor 2 and a refrigerant temperature sensor 43A for detecting the suction refrigerant temperature Ts (low-pressure side refrigerant temperature).

[0020] As described above, the air conditioning unit 20 includes the indoor heat exchangers 21 and 22 therein, and further includes a blower 23 for introducing air from inside the vehicle compartment or outside the vehicle into the interior, and an air damper 24 for adjusting the ratio of the air introduced by the blower 23 that passes through the indoor heat exchanger 21. Also, the air conditioning unit 20 includes an air damper 25 provided upstream of the blower 23 in the air inflow direction for switching the air introduced into the blower 23 to either the air inside the vehicle compartment or the air outside the vehicle.

[0021] In the air conditioning unit 20, the air introduced by the blower 23 passes through the indoor heat exchangers 21 and 22 and is blown into the vehicle compartment. The air introduced by the blower 23 passes through the indoor heat exchanger 22 and then through the indoor heat exchanger 21 and is blown into the interior when the air damper 24 shown in FIG. 1 is fully open. Also, when the air damper 24 is fully closed, the inflow side of the indoor heat exchanger 21 is blocked, and the air introduced by the blower 23 passes only through the indoor heat exchanger 22 and is blown into the vehicle compartment.

[0022] In the air conditioner unit 20, the air damper 25 can selectively close the air inlet 25A connected to the outside and the air inlet 25B connected to the inside of the vehicle, and take in air from either one. Further, in the air conditioner unit 20, by setting the air damper 25 at a desired position between the air inlet 25A and the air inlet 25B, etc., air outside the vehicle or air outside the vehicle can be taken in from both the air inlet 25A and the air inlet 25B at a desired ratio.

[0023] Note that in the external heat exchanger 11 and the indoor heat exchangers 21, 22 described above, an example in which the refrigerant and air directly exchange heat has been described. However, the refrigerant and air may indirectly exchange heat through a heat medium that has exchanged heat with the refrigerant. That is, it may be configured such that the heat of the air is absorbed by the refrigerant through the heat medium, or the heat of the refrigerant is radiated to the air through the heat medium.

[0024] As shown in FIG. 1, the vehicle air conditioner 1 includes a heat medium circuit 30. The heat medium circuit 30 circulates the heat medium by a circulation pump 31, heats the heat medium with a heater (ECH: Electric Coolant Heater) 32, or recovers waste heat from a temperature control object such as a battery with a temperature control target heat exchanger 33. And a refrigerant heat medium heat exchanger 34 for exchanging heat between the refrigerant and the heat medium is provided in the refrigerant circuit 10 and the heat medium circuit 30 through a flow path 34A through which the refrigerant flows and a flow path 34B through which the heat medium flows. The heat medium circuit 30 is provided as necessary.

[0025] [Control device] The vehicle air conditioner 1 includes a control device 100 shown in FIG. 2. The control device 100 controls the refrigerant circuit 10, the air conditioner unit 20, and the heat medium circuit 30 described above based on various input signals 60 (such as an air conditioning instruction signal and a charger connection signal) and detection signals from the sensor unit 40.

[0026] The sensor unit 40 that inputs a detection signal to the control device 100 includes, for example, an outside air sensor 41 that detects the outside air state such as the outside air temperature and the outside air humidity, a compressor current sensor 42 that detects the power consumption (energy consumption) of the compressor 2, a refrigerant temperature sensor 43 and a refrigerant pressure sensor 44 that detect the state of the refrigerant, an occupant sensor 45 that detects the presence or absence of an occupant in the vehicle interior, a blowing air temperature sensor 46 that detects the blowing air temperature of the air conditioning unit 20, and an inside air sensor 47 that detects the state of the vehicle interior such as the inside air temperature and the inside air humidity, and the like.

[0027] In particular, the refrigerant temperature sensor 43 includes a refrigerant temperature sensor 43A that detects the suction refrigerant temperature Ts (low-pressure side refrigerant temperature) sucked into the compressor 2, a refrigerant temperature sensor 43B that detects the outlet refrigerant temperature Tc (high-pressure side refrigerant temperature) of the indoor heat exchanger 21, and a refrigerant temperature sensor 43C that detects the refrigerant temperature TXO (low-pressure side refrigerant temperature) exiting from the external heat exchanger 11 (see FIG. 1).

[0028] Further, the refrigerant pressure sensor 44 includes a refrigerant pressure sensor 44A that detects the suction refrigerant pressure Ps (low-pressure side refrigerant pressure) sucked into the compressor 2, a refrigerant pressure sensor 44B that detects the outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) of the indoor heat exchanger 21, and a refrigerant pressure sensor 44C that detects the refrigerant pressure PXO (low-pressure side refrigerant pressure) exiting from the external heat exchanger 11 (see FIG. 1). These sensors are an example, and the sensor unit 40 is provided with various sensors that detect information necessary when the control device 100 performs various controls.

[0029] The controlled objects of the control device 100 in the refrigerant circuit 10 include the compressor 2, the first decompression unit V1, the second decompression unit V2, the third decompression unit V3, the fourth decompression unit V4, the flow path switching valves 12 and 13, etc. In the air conditioning unit 20, they include the blower 23, the air dampers 24 and 25, etc. In the heat medium circuit 30, they include the circulation pump 31, etc. Further, the control device 100 controls the vehicle air conditioner 1 according to the processing results of the control device 100. In the vehicle air conditioner 1, the control device 100 can execute various operation modes including an endothermic heating mode in which heat is absorbed by the refrigerant in the external heat exchanger 11, and a hot gas heating mode in which the refrigerant compressed by the compressor 2 is radiated in the indoor heat exchanger 21 to heat the vehicle interior without heat being absorbed by the refrigerant in the external heat exchanger 11.

[0030] [Configuration of Control Device in Electric Vehicle (EV)] As shown in FIG. 3, the control device 100 included in the vehicle air conditioner 1 is configured as one ECU connected via the in-vehicle network L to various ECUs (Electronic Control Units) that control the electric vehicle EV. The control device 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an I / F (Interface) 104 for input / output, an I / F (Interface) 105 for in-vehicle communication, etc. Each hardware is interconnected via a bus 106.

[0031] The CPU 101 executes the control of the control device 100 by executing various programs stored in the ROM 102. The ROM 102 is a non-volatile memory. For example, the ROM 102 stores programs executed by the CPU 101, data necessary for the CPU 101 to execute the programs, etc. The RAM 103 is a main memory device such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory).

[0032] For example, the RAM 103 functions as a working area used when the CPU 101 executes a program. The I / F 104 for input / output is connected to various sensors and monitors installed in the EV, inputs data to the CPU 101, and outputs the data processed by the CPU 101 through arithmetic operations. The I / F 105 for in-vehicle communication controls data transmission and reception with other ECUs set in the EV by being connected to the in-vehicle network L.

[0033] When data regarding the surrounding environmental information or data regarding the driving status of the EV is input via the I / F 104 for input / output or the I / F 105 for in-vehicle communication, the control device 100 executes the control of the vehicle air conditioner 1 described above according to the program executed by the CPU 101.

[0034] The EV is equipped with a battery B. The battery B is charged by connecting the plug PS of the charger to the battery plug BP, and power is supplied to the vehicle air conditioner 1 via the battery B. The state in which the plug PS is connected to the battery plug BP is transmitted to the control device 100 via the in-vehicle network L as a charger connection signal.

[0035] [Heat Absorption Heating Mode] Hereinafter, with reference to FIG. 4, the operation of the refrigerant circuit 10 in the heat absorption heating mode will be described. In the heat absorption heating mode, the vehicle air conditioner 1 is an operation mode in which, in the refrigerant circuit 10, refrigerant is caused to flow through the external heat exchanger 11 as follows to absorb heat from the outside air, which is the object to be heated, into the refrigerant to obtain a heat source for heating.

[0036] As shown in FIG. 4, the control device 100 controls the second pressure reducing section V2, the third pressure reducing section V3, the fourth pressure reducing section V4, and the flow path switching valve 12 to be fully closed, and the flow path switching valve 13 and the first pressure reducing section V1 to be opened in the refrigerant circuit 10 in the heat absorption heating mode.

[0037] In the heat absorption heating mode, the high-temperature and high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 in the air conditioner unit 20, is decompressed at the first decompression section V1, the low-pressure refrigerant passes through the external heat exchanger 11, and is returned to the compressor 2 via the flow path switching valve 13, the check valve 14, and the accumulator 16. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the indoor heat exchanger 21, is decompressed at the first decompression section V1 to become a low-pressure refrigerant, absorbs heat and evaporates in the external heat exchanger 11, and returns to the compressor 2. Then, in the air conditioner unit 20, the air introduced by the blower 23 is heated by the heat released in the indoor heat exchanger 21 and blown into the vehicle interior.

[0038] In the heat absorption heating mode, the control device 100 controls the compressor 2 so that the outlet refrigerant pressure Pci (the high-pressure side refrigerant pressure of the refrigerant circuit 10) of the indoor heat exchanger 21 becomes the target outlet refrigerant pressure PCO. Further, the control device 100 controls the opening degree of the first decompression section V1 so that the degree of subcooling at the outlet of the indoor heat exchanger 21 becomes the target degree of subcooling, and controls the blower 23 so that the heating capacity Qhp in the heat absorption heating mode satisfies the target heating capacity TGQh. The target heating capacity TGQh is obtained from the heating requirements such as the set temperature Tset set by the occupant and the requirements from the vehicle (vehicle requirements).

[0039] [Hot gas heating mode] At extremely low temperatures, it is difficult to absorb heat by the external heat exchanger 11, so the hot gas heating mode is used. The hot gas heating mode is an operation mode in which the vehicle interior is heated by releasing heat of a part or all of the refrigerant compressed by the compressor 2 in the indoor heat exchanger 21 without allowing the refrigerant to absorb heat in the external heat exchanger 11.

[0040] The refrigerant circuit 10 of the vehicle air conditioner 1 according to the present embodiment has a hot gas bypass 10V that decompresses at least a part of the refrigerant compressed by the compressor 2 and returns it to the compressor 2 without passing through the indoor heat exchanger 21 and the external heat exchanger 11. A second decompression section V2 is provided in the hot gas bypass 10V. In the hot gas heating mode, the second decompression section V2 is opened to heat the vehicle interior while using the hot gas bypass 10V.

[0041] Hereinafter, the operation of the refrigerant circuit 10 in the hot gas heating mode will be described with reference to FIG. 5. As shown in FIG. 5, in the hot gas heating mode, the control device 100 fully closes the first pressure reducing section V1, the fourth pressure reducing section V4, and the flow path switching valve 13, and controls to open the flow path switching valve 12, the second pressure reducing section V2, and the third pressure reducing section V3.

[0042] In the hot gas heating mode, since the second pressure reducing section V2 in the refrigerant circuit 10 is open, the high-temperature and high-pressure refrigerant discharged from the compressor 2 is branched at the branch point P1 immediately downstream of the compressor 2, and a part of it flows to the hot gas bypass 10V side, and the rest flows to the indoor heat exchanger 21 side. The refrigerant flowing to the hot gas bypass 10V side is decompressed by the second pressure reducing section V2, and at the confluence point P2 immediately upstream of the accumulator 16, it merges with the low-pressure refrigerant decompressed by the third pressure reducing section V3.

[0043] On the other hand, the refrigerant branched at the branch point P1 and flowing to the indoor heat exchanger 21 side passes through the indoor heat exchanger 21 and the flow path switching valve 12, is decompressed by the third pressure reducing section V3 to become a low-pressure refrigerant, passes through the refrigerant heat medium heat exchanger 34, and at the confluence point P2, merges with the refrigerant decompressed by the second pressure reducing section V2. The refrigerant merged at the confluence point P2 is gas-liquid separated by the accumulator 16 and returns to the compressor 2. At this time, in the refrigerant circuit 10, since the first pressure reducing section V1 is fully closed, no refrigerant flows through the external heat exchanger 11, and no heat absorption from the outside air occurs. Also, since the fourth pressure reducing section V4 is fully closed, no refrigerant flows through the indoor heat exchanger 22 either.

[0044] By providing the hot gas bypass 10V as described above, it is possible to mix the gaseous refrigerant that has passed through the hot gas bypass 10V with the liquid refrigerant condensed by heat dissipation in the indoor heat exchanger 21, turn it into a gas-rich refrigerant, and then return it to the compressor 2. Also, by increasing the flow rate of the refrigerant flowing through the hot gas bypass 10V, the amount of heat dissipation in the indoor heat exchanger 21 can be suppressed. By controlling the second decompression unit V2 to adjust the flow rate of the refrigerant flowing through the hot gas bypass 10V, the balance between the amount of heat dissipation in the refrigerant circuit 10 and the amount of heat input to the compressor 2 can be maintained. That is, the second decompression unit V2 functions as a flow rate adjustment unit that adjusts the flow rate of the refrigerant flowing through the hot gas bypass 10V.

[0045] In the hot gas heating mode, among the refrigerants flowing through the refrigerant circuit 10, the refrigerant flowing through the flow path passing through the indoor heat exchanger 21 is decompressed by the third decompression unit V3. Therefore, the upstream side of the third decompression unit V3 becomes high-pressure refrigerant, and the downstream side of the third decompression unit V3 becomes low-pressure refrigerant. At this time, it is important for maintaining the heating capacity that no heat exchange occurs in the refrigerant heat medium heat exchanger 34 in the flow path of the low-pressure refrigerant. And in the air conditioning unit 20, the air introduced by the blower 23 is heated by heat dissipation in the indoor heat exchanger 21 and blown into the vehicle interior.

[0046] In the hot gas heating mode, the control device 100 controls the compressor 2 so that the outlet refrigerant pressure Pci (the high-pressure side refrigerant pressure of the refrigerant circuit 10) of the indoor heat exchanger 21 becomes the target outlet refrigerant pressure PCO. Also, the control device 100 controls the opening degrees of the second decompression unit V2 and the third decompression unit V3 so that the suction refrigerant pressure Ps (the low-pressure side refrigerant pressure of the refrigerant circuit 10) of the compressor 2 in the refrigerant circuit 10 becomes the target suction refrigerant pressure PSO, and controls the blower 23 so that the heating capacity Qhg in the hot gas heating mode satisfies the target heating capacity TGQh.

[0047] As described above, since the hot gas heating mode has a higher achievable heating capacity than the endothermic heating mode, heating can be effectively performed even at extremely low temperatures. On the one hand, as will be described later, there may be a case where the same target heating capacity TGQh can be satisfied by either the hot gas heating mode or the heat absorption heating mode. In this case, since the hot gas heating mode has a lower operating efficiency than the heat absorption heating mode, the rotational speed of the compressor 2 increases and the power consumption increases.

[0048] That is, as described above, in the hot gas heating mode, a part of the refrigerant compressed in the compressor 2 is made to flow into the hot gas bypass 10V and returned to the compressor 2, thereby increasing the suction refrigerant pressure Ps of the compressor 2, and thereby increasing the discharge pressure of the compressor 2. On the other hand, the flow rate of the refrigerant flowing into the indoor heat exchanger 21 decreases by the amount that has flowed into the hot gas bypass 10V. For this reason, in the hot gas heating mode, in order to ensure the heat dissipation amount in the indoor heat exchanger 21 and achieve the same target heating capacity TGQh as in the heat absorption heating mode, the rotational speed of the compressor 2 is made higher than that in the heat absorption heating mode. Therefore, in the hot gas heating mode, the power consumption becomes larger than that in the heat absorption heating mode.

[0049] [Transition Control of Operating Mode by Control Device] Hereinafter, the transition control of the operating mode by the control device 100 when the vehicle air conditioner 1 according to the present embodiment performs heating in the vehicle interior will be described. When the vehicle air conditioner 1 performs heating in the vehicle interior, the control device 100 executes either the heat absorption heating mode or the hot gas heating mode according to the external environment such as the outside air temperature Tam, the set temperature Tset, the target heating capacity TGQh, and the like.

[0050] In the control device 100, usually, when the outside air temperature Tam is equal to or higher than a predetermined temperature (for example, -10°C), the heat absorption heating mode is executed to suppress the power consumption, and when the outside air temperature Tam is in an extremely low temperature environment lower than the predetermined temperature, the hot gas heating mode is executed to ensure the heating capacity.

[0051] On the one hand, during the execution of the hot gas heating mode, when the vehicle interior reaches the set temperature Tset and is in a stable state, the heating capacity Qhp in the heat absorption heating mode may be able to satisfy the target heating capacity TGQh. On the contrary, during the execution of the heat absorption heating mode, if the outside air temperature Tam drops or the frosting state of the external heat exchanger 11 progresses, etc., due to changes in the external environment, the heating capacity Qhp may decrease. In this case, the heating capacity Qhp in the heat absorption heating mode may not be able to satisfy the target heating capacity TGQh.

[0052] Therefore, when the control device 100 executes the heat absorption heating mode, it determines whether the target heating capacity TGQh can be satisfied by the heating capacity Qhp achievable in the external environment, and based on this determination result, decides whether to execute either the heat absorption heating mode or the hot gas heating mode.

[0053] That is, the control device 100 executes the heat absorption heating mode when the heating capacity Qhp of the heat absorption heating mode can satisfy the target heating capacity TGQh, and executes the hot gas heating mode when it cannot be satisfied. Then, the control device 100 also determines whether a transition from the currently executing operation mode is necessary, and performs heating in the vehicle interior while appropriately switching between the heat absorption heating mode and the hot gas heating mode as needed. By controlling in this way, in the vehicle air conditioner 1, it is possible to perform heating operation while suppressing power consumption while satisfying the target heating capacity TGQh.

[0054] By the way, as described above, in the refrigerant circuit 10, the refrigerant flow during the execution of the heat absorption heating mode (see Fig. 4) and the refrigerant flow during the execution of the hot gas heating mode (see Fig. 5) are significantly different in the refrigerant flow path. Specifically, in the heat absorption heating mode and the hot gas heating mode, in the refrigerant circuit 10, the opening and closing states of the first pressure reducing section V1, the second pressure reducing section V2, the third pressure reducing section V3, and the flow path switching valves 12, 13 are in a completely opposite state. Also, the range of achievable heating capacity is different between the hot gas heating mode and the heat absorption heating mode, and the pressure ranges (pressure bands) of the refrigerant suitable for each to continue operation stably are significantly different.

[0055] For these reasons, when switching between the hot gas heating mode and the heat absorption heating mode, if all the opening and closing states of the above-described first decompression part V1 to third decompression part V3 and flow path switching valves 12 and 13 are controlled to be switched all at once, the flow path of the refrigerant changes suddenly, and accordingly, the pressure of the refrigerant fluctuates greatly, and there is a risk of deviating from the pressure range suitable for each heating mode.

[0056] Therefore, when transitioning from the heat absorption heating mode to the hot gas heating mode, the control device 100 transitions to the hot gas heating mode after executing the first transition mode. Similarly, when transitioning from the hot gas heating mode to the heat absorption heating mode, the control device 100 transitions to the heat absorption heating mode after executing the second transition mode.

[0057] Hereinafter, (1) the transition process of the operation mode (including the determination of the operation mode, the determination of the necessity of transition, and a series of processes of transition), (2) the process in the first transition mode (the transition process from the heat absorption heating mode to the hot gas heating mode), and (3) the process in the second transition mode (the transition process from the hot gas heating mode to the heat absorption heating mode) in the control device 100 of the vehicle air conditioner 1 according to the present embodiment will be described respectively.

[0058] (1) Transition process of operation mode FIG. 6 is a flowchart relating to the control process of the control device 100 during the heating operation of the vehicle air conditioner 1. As described above, the control device 100 performs heating of the vehicle interior while appropriately switching between the heat absorption heating mode and the hot gas heating mode as needed. The series of processes from "START" to "END" in the flowchart of FIG. 6 are repeatedly performed at a predetermined time interval during the execution of the heating operation in the vehicle air conditioner 1.

[0059] The control device 100 acquires environmental information at a predetermined cycle during the heating operation (step S11). The environmental information includes external environmental information of the vehicle such as the outside air temperature Tam detected by the outside air sensor 41, and vehicle environmental information such as the vehicle interior temperature, the set temperature Tset, and the frosting state of the external heat exchanger 11. Here, the frosting state of the external heat exchanger 11 can be acquired based on, for example, the difference between the refrigerant temperature TXO obtained by the refrigerant temperature sensor 43C provided on the outlet side of the external heat exchanger 11 and the outside air temperature Tam obtained by the outside air sensor 41.

[0060] Next, the control device 100 estimates the heating capacity Qhp that can be realized in the endothermic heating mode (step S12). Since the heating capacity Qhp that can be realized varies depending on the outside air temperature Tam in the endothermic heating mode, the control device 100 needs to grasp the heating capacity Qhp based on the outside air temperature Tam. Further, in the endothermic heating mode, since heat is obtained by absorbing heat from the outside air into the refrigerant in the external heat exchanger 11, the heat absorption amount changes depending on the presence or absence and state of frosting of the external heat exchanger 11, and accordingly, the realizable heating capacity Qhp varies.

[0061] Therefore, in the present embodiment, for example, based on the environmental information acquired in step S11, the control device 100 reads out a heating capacity Qhp_map corresponding to the outside air temperature Tam from a map or the like stored in the ROM102 or the like, and estimates the actually realizable heating capacity Qhp while considering the frosting state of the external heat exchanger 11 (step S12).

[0062] Note that the above-mentioned map associates, for example, the outside air temperature Tam with the heating capacity Qhp_map in the endothermic heating mode that can be realized according to the outside air temperature Tam, and is stored in the ROM102 in advance. In addition, an arithmetic expression for calculating the heating capacity Qhp from the outside air temperature Tam may be stored in the ROM102 or the like in advance, and calculated each time based on the acquired outside air temperature Tam.

[0063] The control device 100 calculates the target heating capacity TGQh (step S13), and determines whether the heating capacity Qhp achievable by the endothermic heating mode estimated in step S12 satisfies the target heating capacity TGQh (step S14). When the heating capacity Qhp satisfies the target heating capacity TGQh (YES in step S14), it determines to execute the endothermic heating mode (referred to as "HP Mode" in the figure) (step S15). When the currently executing operation mode is the endothermic heating mode and no transition is required (NO in step S16), the control device 100 ends the above processing. On the other hand, when the currently executing operation mode is the hot gas heating mode and a transition is necessary (YES in step S16), the control device 100 executes the second transition mode (step S17). The second transition mode will be described later.

[0064] In the determination in step S14, when the heating capacity Qhp does not satisfy the target heating capacity TGQh (NO in step S14), the control device 100 determines to execute the hot gas heating mode (referred to as "HG Mode" in the figure) (step S18). When the currently executing operation mode is the hot gas heating mode and no transition is required (NO in step S19), the control device 100 ends the above processing. On the other hand, when the currently executing operation mode is the endothermic heating mode and a transition is necessary (YES in step S19), the control device 100 executes the first transition mode (step S20). The first transition mode will be described later.

[0065] (2) Processing in the first transition mode FIG. 7 is a flowchart showing the transition process from the endothermic heating mode to the hot gas heating mode (HP→HG). When the control device 100 determines that a transition from the endothermic heating mode to the hot gas heating mode is necessary, it causes a transition to the hot gas heating mode by executing a first transition mode. In the endothermic heating mode and the hot gas heating mode, as described above, in the refrigerant circuit 10, the first decompression unit V1, the second decompression unit V2, the third decompression unit V3, and the flow path switching valves 12 and 13 are in different open / closed states. The control device 100 controls these open / closed states step by step by executing the first transition mode, thereby changing the refrigerant flow path step by step and suppressing a rapid change in the refrigerant pressure to achieve a seamless transition from the endothermic heating mode to the hot gas heating mode.

[0066] When the first transition mode is started, the control device 100 first controls the second decompression unit V2 to open to a predetermined opening degree as shown in FIG. 8 from the operating state of the refrigerant circuit 10 in the endothermic heating mode shown in FIG. 4 (step S31). In this way, by first opening the second decompression unit V2 and allowing the high-temperature and high-pressure refrigerant compressed by the compressor 2 to flow through the hot gas bypass 10V, the suction refrigerant pressure Ps can be increased.

[0067] Here, by setting the predetermined opening degree of the second decompression unit V2 to the minimum opening degree defined by the specifications of the second decompression unit V2, the suction refrigerant pressure Ps can be gradually increased. Also, the predetermined opening degree of the second decompression unit V2 is set to an opening degree such that the refrigerant pressure on the downstream side of the second decompression unit V2 becomes lower than the refrigerant pressure on the downstream side of the first decompression unit V1. Thereby, the check valve 14 provided downstream of the external heat exchanger 11 can be opened, and the retention of the refrigerant in the external heat exchanger 11 can be prevented.

[0068] Note that, by flowing the refrigerant through the hot gas bypass 10V in step S31, the flow rate of the refrigerant to the indoor heat exchanger 21 decreases. As a result, the sense of insufficiency with respect to the target heating capacity TGQh becomes even greater, and there is a risk that the comfort of the occupants will decrease. Therefore, the control device 100 controls the blower 23 and the air dampers 24 and 25 in the air conditioning unit 20 as necessary to adjust the air volume, the heat dissipation amount of the indoor heat exchanger 21, the ratio of the inside and outside air, and the like. By doing so, it is possible to reduce the sense of insufficiency with respect to the target heating capacity TGQh during the execution of the first transition mode and reduce the discomfort of the occupants.

[0069] After the second decompression part V2 opens to a predetermined opening degree, the control device 100 controls to close the first decompression part V1 (step S32), and at the same time, controls the third decompression part V3 to open from the closed state to a predetermined opening degree (step S33). Also, the flow path switching valve 12 is set to the open state.

[0070] At this time, the control device 100 controls so that the timing (time) when the opening degree of the first decompression part V1 becomes 0 (fully closed) coincides with the timing (time) when the third decompression part V3 becomes a predetermined opening degree. As described above, since the pressure ranges of the refrigerant suitable for stably continuing the operation in the endothermic heating mode and the hot gas heating mode are different, if the opening and closing timings of the first decompression part V1 and the third decompression part V3 do not coincide, the following problems may occur.

[0071] That is, when the opening and closing timings of the first pressure reducing section V1 and the third pressure reducing section V3 do not match, particularly when both are in a closed state, the outlet refrigerant pressure Pci and the suction refrigerant pressure Ps of the compressor 2 increase, and there is a risk that the compressor 2 may stop due to abnormal high pressure. Further, for example, if the third pressure reducing section V3 opens to a predetermined opening degree before the first pressure reducing section V1 is fully closed, there is a risk that refrigerant may accumulate in the external heat exchanger 11 due to the pressure difference between the refrigerant flowing from the first pressure reducing section V1 side and the refrigerant flowing from the third pressure reducing section V3 side. Therefore, by matching the opening and closing timings of the first pressure reducing section V1 and the third pressure reducing section V3 by the control device 100, it is not necessary to perform complicated opening degree adjustment for the first pressure reducing section V1 to the third pressure reducing section V3, and while simplifying the control of the first pressure reducing section V1 to the third pressure reducing section V3, the above problems can be prevented.

[0072] The control device 100 controls the first pressure reducing section V1 to close at a constant speed, and similarly, controls the third pressure reducing section V3 to open at a constant speed. In this case, since the opening degree of the first pressure reducing section V1 before closing and the predetermined opening degree of the third pressure reducing section V3 are not necessarily the same opening degree, the driving speed of the first pressure reducing section V1 and the driving speed of the third pressure reducing section V3 do not necessarily match.

[0073] Alternatively, the control device 100 may control by shifting the start timing of closing the first pressure reducing section V1 and the start timing of opening the third pressure reducing section V3 so that the timing when the opening degree of the first pressure reducing section V1 becomes 0 (fully closed) and the timing when the third pressure reducing section V3 becomes a predetermined opening degree match.

[0074] The predetermined opening degree of the third pressure reducing section V3 can be, for example, an opening degree obtained through experiments or simulations and is the minimum opening degree within the pressure range in which the hot gas heating mode is established. In addition, the control device 100 may determine the predetermined opening degree of the third pressure reducing section V3 based on the target suction refrigerant pressure PSO that can achieve the target outlet refrigerant pressure PCO calculated from the set temperature Tset.

[0075] When the above process is completed, in the vehicle air conditioner 1, the hot gas heating mode is executed as the heating operation. That is, the control device 100 controls the opening degrees of the second decompression part V2 and the third decompression part V3 so that the suction refrigerant pressure Ps becomes the target suction refrigerant pressure PSO and the outlet refrigerant pressure Pci of the indoor heat exchanger 21 becomes the target outlet refrigerant pressure PCO, and controls the blower 23 etc. so that the heating capacity Qhg in the hot gas heating mode satisfies the target heating capacity TGQh.

[0076] (3) Processing in the second transition mode FIG. 9 is a flowchart showing the transition process from the hot gas heating mode to the heat absorption heating mode (HG→HP). When the control device 100 determines that a transition from the hot gas heating mode to the heat absorption heating mode is necessary, it executes the second transition mode to transition to the heat absorption heating mode. As described above, in the heat absorption heating mode and the hot gas heating mode, in the refrigerant circuit 10, the first decompression part V1, the second decompression part V2, the third decompression part V3, and the flow path switching valves 12, 13 are in different open / closed states. The control device 100 executes the second transition mode to gradually control these open / closed states to gradually change the refrigerant flow path, suppress a rapid change in the refrigerant pressure, and realize a seamless transition from the hot gas heating mode to the heat absorption heating mode.

[0077] In the hot gas heating mode, since both the suction refrigerant pressure Ps and the outlet refrigerant pressure Pci are higher than those in the heat absorption heating mode, it is necessary to approach the suction refrigerant pressure Ps and the outlet refrigerant pressure Pci suitable for the heat absorption heating mode as much as possible. Therefore, in the second transition mode, the heat medium is temporarily heated in the refrigerant heat medium heat exchanger 34 by the heat of the refrigerant (hereinafter, surplus heat) that is surplus in the hot gas heating mode, and the refrigerant absorbs heat from the heated heat medium to adjust the pressure range of the refrigerant to a pressure range suitable for the heat absorption heating mode.

[0078] When the second transition mode is started, as shown in FIG. 10, from the operating state of the refrigerant circuit 10 in the hot gas heating mode shown in FIG. 5, the control device 100 drives the circulation pump 31 (step S41). Thereby, the heat medium is circulated through the heat medium circuit 30 to cause heat exchange between the heat medium and the refrigerant in the refrigerant heat medium heat exchanger 34. That is, the refrigerant circuit 10 is in a state of performing heating operation in the hot gas heating mode and simultaneously dissipating heat in the refrigerant heat medium heat exchanger 34. Thereby, the surplus heat in the hot gas heating mode is dissipated to the heat medium in the heat medium circuit 30, and the suction refrigerant pressure Ps is reduced.

[0079] Note that prior to driving the circulation pump 31, it is preferable to control the compressor 2 and the blower 23 with the target suction refrigerant pressure PSO and the target discharge refrigerant pressure PCO as the minimum values at which the hot gas heating mode can operate, and then dissipate the surplus heat in the hot gas heating mode to the heat medium in the heat medium circuit 30. By doing so, the transition from the hot gas heating mode to the heat absorption heating mode can be performed more seamlessly.

[0080] Note that due to this operation, heat dissipation of the refrigerant also occurs in the refrigerant heat medium heat exchanger 34 in addition to the indoor heat exchanger 21, so the blow-out temperature may decrease and the comfort of the occupant may be impaired. In this case, the control device 100 controls the blower 23, the air dampers 24 and 25 in the air conditioning unit 20 as necessary to adjust the air volume, the heat dissipation amount of the indoor heat exchanger 21, the ratio of the inside and outside air, etc.

[0081] The control device 100 causes the refrigerant circuit 10 to dissipate the surplus heat in the hot gas heating mode to the heat medium circulating through the heat medium circuit 30 in a state of performing heating operation in the hot gas heating mode and dissipating heat in the refrigerant heat medium heat exchanger 34. Then, the control device 100 monitors whether the surplus heat has been sufficiently dissipated to the heat medium, that is, whether the heat dissipation has been completed (step S42). In this way, by dissipating the surplus heat in the hot gas heating mode to the heat medium as much as possible, a rapid change in the suction refrigerant pressure Ps when the second decompression section V2 is closed in the next step S43 is suppressed.

[0082] In step S42, for example, when the heat medium temperature Wt is approximately equal to the refrigerant saturation temperature at a pressure close to the suction refrigerant pressure Ps in the hot gas heating mode (first temperature Wt1), sufficient excess heat is dissipated, which can be regarded as a criterion for determining that the heat dissipation is completed.

[0083] Also, the control device 100 can determine that the heat dissipation of the excess heat is completed in the following cases. That is, the control device 100 checks whether the difference between the refrigerant temperature at the outlet of the refrigerant heat medium heat exchanger 34 and the heat medium temperature is within a certain temperature range (for example, within 2°C), or checks whether the difference in the heat medium temperature at the inlet and outlet of the refrigerant heat medium heat exchanger 34 is within a certain range (for example, within 5°C), and can determine that the heat dissipation of the excess heat is completed.

[0084] When the control device 100 determines that the heat dissipation of the excess heat is completed (YES in step S42), it controls to close the second decompression part V2 as shown in FIG. 11 (step S43). Thereby, the refrigerant absorbs the heat of the heat medium in the refrigerant heat medium heat exchanger 34 (referred to as "heat recovery").

[0085] At the same time, the control device 100 controls the third decompression part V3 so that the degree of subcooling of the outlet refrigerant of the indoor heat exchanger 21 becomes the target degree of subcooling (SC (subcooling) control) (step S44). Note that since the heat recovery, that is, the heat absorption from the heat medium by the refrigerant, is only temporarily performed, the excess heat in the hot gas heating mode and the waste heat recovered from the temperature control object are stored in the heat medium, and this is absorbed by the refrigerant.

[0086] When the second pressure reducing section V2 is closed and the outlet refrigerant pressure Pci decreases together with the suction refrigerant pressure Ps, the control device 100 controls the blower 23 and the air dampers 24, 25 to temporarily adjust the air volume passing through the indoor heat exchanger 21, thereby adjusting the heat dissipation amount in the indoor heat exchanger 21. By doing so, the balance between heat input and heat dissipation in the hot gas heating mode can be maintained, and the operation can be stably continued, and the above-mentioned heat recovery can be smoothly executed.

[0087] After the second pressure reducing section V2 is fully closed and the transition to heat recovery is completed, the control device 100 immediately controls to open the first pressure reducing section V1 (step S45). At the same time, the flow path switching valve 13 is set to the open state. As a result, the external heat exchanger 11 and the refrigerant heat medium heat exchanger 34 both function as evaporators, and the refrigerant absorbs heat from both the outside air and the heat medium (FIG. 12). At this time, the first pressure reducing section V1 is set to the minimum opening degree determined by the specifications of the first pressure reducing section V1. As shown in FIG. 12, when the first pressure reducing section V1 is opened, since the third pressure reducing section V3 is in the open state and under subcooling control, it is preferable to set the first pressure reducing section V1 to a predetermined fixed opening degree at this stage.

[0088] Subsequently, the control device 100 determines whether or not frosting has occurred on the external heat exchanger 11 (step S46). As described above, the control device 100 determines the frosting state of the external heat exchanger 11 based on, for example, the refrigerant temperature TXO obtained by the refrigerant temperature sensor 43C provided on the outlet side of the external heat exchanger 11. If it is determined that there is no frosting (NO in step S46), the transition to the endothermic heating mode is advanced. That is, the control device 100 closes the third pressure reducing section V3 (step S47), controls the first pressure reducing section V1 so that the degree of subcooling (subcooling) of the outlet refrigerant of the indoor heat exchanger 21 becomes the target degree of subcooling (SC (subcooling) control) (step S48), and stops the circulation pump 31 (step 49).

[0089] When the above processing is completed, in the vehicle air conditioner 1, the heat absorption heating mode is executed as the heating operation. That is, the control device 100 controls the compressor 2 so that the outlet refrigerant pressure Pci of the indoor heat exchanger 21 becomes the target outlet refrigerant pressure PCO. Further, the control device 100 controls the opening degree of the first decompression part V1 so that the degree of subcooling at the outlet of the indoor heat exchanger 21 becomes the target degree of subcooling, and controls the blower 23 so that the heating capacity Qhp in the heat absorption heating mode satisfies the target heating capacity TGQh.

[0090] On the other hand, when it is determined that there is frost formation on the outdoor heat exchanger 11 (YES in step S46), the control device 100 causes the refrigerant to absorb the heat of the heat medium and monitors until the heat medium temperature Wt of the heat medium circuit 30 becomes equal to or lower than the second temperature Wt2 (step S50). When the heat medium temperature Wt becomes equal to or lower than the second temperature Wt2 (YES in step S50), the transition process to the heat absorption heating mode is stopped (step S51), and the hot gas heating mode is returned to (step S52). Note that the second temperature Wt2 is the heat medium temperature at which the target heating capacity TGQh cannot be satisfied in heat recovery.

[0091] When returning to the hot gas heating mode in step S52, the control device 100 opens the second decompression part V2 to the minimum opening degree, stops the circulation pump 31 when the suction refrigerant pressure Ps reaches the desired pressure, controls the third decompression part V3 to have the opening degree in the hot gas heating mode, and closes the first decompression part V1. Further, in the above example, in step S50, the heat medium temperature Wt is monitored until it becomes equal to or lower than the second temperature Wt2, but it is also possible to proceed to step S51 when a predetermined time has elapsed.

[0092] When the above processing is completed, in the vehicle air conditioner 1, the hot gas heating mode is executed as the heating operation. That is, the control device 100 controls the compressor 2 so that the outlet refrigerant pressure Pci of the indoor heat exchanger 21 becomes the target outlet refrigerant pressure PCO, controls the opening degrees of the second decompression part V2 and the third decompression part V3 so that the suction refrigerant pressure Ps becomes the target suction refrigerant pressure PSO, and controls the blower 23 and the like so that the heating capacity Qhg in the hot gas heating mode satisfies the target heating capacity TGQh.

[0093] Thus, in the vehicle air conditioner 1 according to the present embodiment, by comparing the achievable heating capacity in the endothermic heating mode or the hot gas heating mode with the target heating capacity and executing the optimal heating mode, it is possible to always ensure the required heating capacity while suppressing power consumption as much as possible, and to improve the comfort of the passengers while suppressing power consumption.

[0094] Further, when the control device 100 makes a transition from the endothermic heating mode to the hot gas heating mode, it makes a transition to the hot gas heating mode after executing the first transition mode. Similarly, when making a transition from the hot gas heating mode to the endothermic heating mode, it makes a transition to the endothermic heating mode after executing the second transition mode.

[0095] By executing the first transition mode or the second transition mode, when making a transition between the endothermic heating mode and the hot gas heating mode, the flow path of the refrigerant in the refrigerant circuit 10 is changed step by step, and the pressure of the refrigerant is gently decreased or increased. As a result, the pressure of the refrigerant can be set to a pressure suitable for the heating mode after the transition, so that a seamless transition can be made while the compressor is being driven, and the comfort of the passengers can be improved.

[0096] That is, in the first transition mode, the first decompression section, the second decompression section, and the third decompression section are controlled to be opened and closed step by step, and the suction refrigerant pressure Ps is gently increased, so that the difference in the pressure range between the endothermic heating mode and the hot gas heating mode can be gently filled. As a result, it is possible to seamlessly transition from the endothermic heating mode to the hot gas heating mode while driving the compressor 2. Further, during the transition, the air conditioning unit 20 is controlled as necessary, so that a sense of shortage of heating capacity can be compensated by adjusting the air volume or the like. Thus, by executing the first transition mode when making a transition from the endothermic heating mode to the hot gas heating mode, the comfort of the passengers is improved.

[0097] Also, when transitioning from the hot gas heating mode to the endothermic heating mode by the second transition mode, the heat medium in the heat medium circuit 30 absorbs the excess heat accumulated in the refrigerant in the hot gas heating mode and gradually reduces the suction refrigerant pressure Ps, thereby gradually filling the difference in the pressure band between the endothermic heating mode and the hot gas heating mode. As a result, it is possible to seamlessly transition from the hot gas heating mode to the endothermic heating mode while driving the compressor 2, improving the comfort of the occupants.

[0098] As described above, according to the present embodiment, the transition between the hot gas heating mode and the endothermic heating mode can be performed seamlessly, improving the comfort of the occupants.

[0099] Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and design changes and the like within the scope not departing from the gist of the present invention are also included in the present invention.

Description of Reference Numerals

[0100] 1: Vehicle air conditioner, 2: Compressor, 10: Refrigerant circuit, 10V: Hot gas bypass 11: External heat exchanger, 12, 13: Flow path switching valves, 14, 15: Check valves 16: Accumulator, 20: Air conditioning unit, 21, 22: Indoor heat exchangers 23: Blower, 24, 25: Air dampers, 25A, 25B: Air inlets 30: Heat medium circuit, 31: Circulation pump, 33: Heat exchanger to be temperature-controlled 34: Refrigerant - heat medium heat exchanger, 34A, 34B: Flow paths, 40: Sensor unit 41: Outside air sensor, 42: Compressor current sensor 43, 43A, 43B, 43C: Refrigerant temperature sensors 44, 44A, 44B, 44C: Refrigerant pressure sensors, 45: Occupant sensor 46: Air supply temperature sensor, 47: Inside air sensor, 60: Input signal 100: Control device

Claims

1. A refrigerant circuit including a compressor, an indoor heat exchanger, an outdoor heat exchanger, and a hot gas bypass that decompresses at least a part of the refrigerant compressed by the compressor and returns it to the compressor without passing through the indoor heat exchanger and the outdoor heat exchanger; A heat medium circuit that circulates a heat medium that exchanges heat with the refrigerant in a refrigerant heat medium heat exchanger provided in the refrigerant circuit; In a vehicle air conditioner including a control device that controls the refrigerant circuit and the heat medium circuit, The refrigerant circuit, Includes a first decompression unit that decompresses the refrigerant flowing into the outdoor heat exchanger, and a second decompression unit that decompresses the refrigerant flowing through the hot gas bypass; The control device, Is capable of executing an endothermic heating mode in which the refrigerant absorbs heat in the outdoor heat exchanger, and a hot gas heating mode in which a part of the refrigerant compressed by the compressor flows through the hot gas bypass and the rest flows through the indoor heat exchanger; During the execution of the hot gas heating mode, when it is determined that the heating capacity in the endothermic heating mode satisfies the target heating capacity, A first stage of controlling to radiate the heat of the surplus refrigerant in the hot gas heating mode in the refrigerant heat medium heat exchanger to heat the heat medium; A second stage of closing the second decompression unit and controlling the refrigerant to absorb heat from the heat medium in the refrigerant heat medium heat exchanger; A third stage of controlling to open the first decompression unit; A vehicle air conditioner that, after executing a second transition mode that sequentially performs a fourth stage of controlling to stop the refrigerant from absorbing heat from the heat medium in the refrigerant heat medium heat exchanger, transitions to the endothermic heating mode.

2. The control device, Performs the first stage when the minimum heating capacity at which the hot gas heating mode is established is greater than the target heating capacity. The vehicle air conditioner according to claim 1.

3. The control device, In the first stage, when at least one of the temperature difference between the outlet heat medium temperature of the heat medium and the outlet refrigerant temperature of the refrigerant in the refrigerant heat medium heat exchanger is within a first range, or the temperature difference between the inlet heat medium temperature and the outlet heat medium temperature of the heat medium in the refrigerant heat medium heat exchanger is within a second range, executes the second stage. The vehicle air conditioner according to claim 1.

4. The control device, During the execution of the second transition mode, when frosting on the outdoor heat exchanger is detected, The vehicle air conditioner according to claim 1, which controls the refrigerant heat medium heat exchanger to continue heat absorption from the heat medium to the refrigerant.

5. The control device When detecting frosting on the external heat exchange unit, when heat absorption from the heat medium to the refrigerant in the refrigerant heat medium heat exchanger continues, when a predetermined time or more has elapsed, or when the temperature of the heat medium becomes equal to or lower than the second temperature, controls to return to the hot gas heating mode. The vehicle air conditioner according to claim 4.

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