Vehicle air conditioning device

Abstract

[Problem] To improve comfort of an occupant by achieving a desired blowout temperature while ensuring a heat radiation amount required with an increase in a heating load and stably continuing a hot gas heating mode. [Solution] This vehicle air conditioning device includes: a refrigerant circuit; an air conditioning unit; and a control device for controlling the refrigerant circuit and the air conditioning unit. The vehicle air conditioning device can execute a hot gas heating mode in which a part of a refrigerant compressed by a compressor is bypassed and returned to the compressor and the remainder heats the inside of the cabin by heat radiation of the refrigerant. When it is determined that the heating load has increased during execution of the hot gas heating mode, control is performed so as to expand an increase range of the target rotation speed of the compressor.

Description

Vehicle air conditioning system

[0001] The present invention relates to an air conditioning system for a vehicle.

[0002] In recent years, vehicles such as hybrid vehicles and electric vehicles, which have a traction motor powered by power supplied from an onboard battery, have become widespread. A known vehicle air conditioner for such vehicles uses a heat pump (refrigerant circuit) as a heat source.

[0003] In a vehicle air conditioning system using a heat pump, an external heat exchanger, such as an exterior heat exchanger, located outside the vehicle cabin functions as a heat absorber during heating operation to obtain a heating heat source from outside air, etc. (endothermic heating). Therefore, when the outside temperature becomes extremely low, it becomes difficult to absorb heat from outside air, etc., and heating capacity is significantly reduced. In contrast, hot gas heating, which does not absorb heat from outside air, etc., but uses a high-temperature, high-pressure refrigerant discharged from a compressor, is known as an effective heating method in extremely low-temperature environments.

[0004] For example, in the vehicle air conditioning system of Patent Document 1, a hot gas heating mode is executed in which a portion of the high-temperature, high-pressure refrigerant discharged from the compressor is passed through a bypass flow path to be decompressed and then returned to the compressor, while the remainder is heat exchanged with the air blown into the passenger compartment in an indoor heat exchanger, then decompressed and returned to the compressor without passing through an external heat exchanger.

[0005] Japanese Patent Application Laid-Open No. 2023-46604

[0006] The hot gas heating mode is an operating mode in which the heat generated by the compressor is used to heat the air to be blown, and the amount of work (heat input) done by the compressor is the air heating capacity (heat dissipation capacity) of the indoor heat exchanger. Therefore, in order to operate the vehicle air conditioner stably in the hot gas heating mode, each component is controlled to balance the amount of heat input to the compressor and the amount of heat dissipated by the indoor heat exchanger.

[0007] When the refrigerant flow rate is constant, the amount of heat dissipated by the indoor heat exchanger depends on the volume of air blown by the fan and passing through the indoor heat exchanger, so the amount of heat dissipated by the indoor heat exchanger varies depending on the operating state of the fan. In other words, when the fan is operated at the maximum rotation speed, the volume of air passing through the indoor heat exchanger is at its maximum, and the amount of heat dissipated by the indoor heat exchanger is also at its maximum.

[0008] Therefore, for example, if the heating load increases while the blower is operating at maximum rotation speed, the heat input to the compressor increases, but the heat dissipation rate at the indoor heat exchanger cannot be increased, resulting in a larger heat input relative to the heat dissipation rate, making it impossible to maintain a balance between the heat input and the heat dissipation rate. In this case, the pressure and temperature of the refrigerant on the intake side (low-pressure side) of the compressor increase, and accordingly, the pressure and temperature of the refrigerant on the discharge side (high-pressure side) also increase. This causes the pressure of the refrigerant on the discharge side (high-pressure side) to exceed its upper limit, preventing stable operation of the hot gas heating mode and potentially causing the vehicle air conditioning system to shut down.

[0009] On the other hand, if the heat input to the compressor is suppressed in order to balance the heat input to the compressor and the heat dissipation to the indoor heat exchanger, there is a problem in that the desired heating cannot be performed in response to an increase in heating load, i.e., the blowing temperature cannot be raised to the desired temperature.

[0010] The present invention was made in consideration of these circumstances, and aims to achieve the desired blow-out temperature while stably continuing the hot gas heating mode by ensuring the amount of heat dissipation required as the heating load increases, thereby improving the comfort of occupants.

[0011] One aspect of the present invention provides a vehicle air conditioning system comprising: a refrigerant circuit including a compressor, an indoor heat exchange unit, an external heat exchange unit, and a hot gas bypass that decompresses and returns at least a portion of the refrigerant compressed by the compressor without passing through the indoor heat exchange unit and the external heat exchange unit; an air conditioning unit in which the indoor heat exchange unit is disposed, an air damper that adjusts the ratio of indoor and outdoor air to be introduced into the unit, and a blower that blows the introduced air; and a control device that controls the refrigerant circuit and the air conditioning unit and is capable of executing a hot gas heating mode in which a portion of the refrigerant compressed by the compressor flows through the hot gas bypass and returns to the compressor, and the remainder dissipates heat in the indoor heat exchange unit.In this vehicle air conditioning system, when it is determined that the heating load has increased while the hot gas heating mode is being executed, the control device controls the vehicle air conditioning system to expand the increase range of the target rotation speed of the compressor.

[0012] According to the present invention, by ensuring the amount of heat dissipation required as the heating load increases, it is possible to achieve the desired blow-out temperature while stably continuing the hot gas heating mode, thereby improving the comfort of occupants.

[0013] Fig. 1 is an explanatory diagram showing an example of the system configuration of a vehicle air conditioner according to an embodiment of the present invention; Fig. 2 is an explanatory diagram showing a control device of a vehicle air conditioner according to an embodiment of the present invention; Fig. 3 is a diagram showing the configuration of a control device, etc., in an electric vehicle (EV) according to an embodiment of the present invention; Fig. 4 is an explanatory diagram showing the operation of a refrigerant circuit in a hot gas heating mode in a vehicle air conditioner according to an embodiment of the present invention; Fig. 5 is a flowchart showing the processing flow when a heating load increases while a hot gas heating mode is being executed in a vehicle air conditioner according to an embodiment of the present invention;

[0014] Hereinafter, an embodiment 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 with the same function, and duplicated explanations in each drawing will be omitted as appropriate. In the drawings, bold black lines in the refrigerant circuit 10 indicate refrigerant flow paths through which high-pressure refrigerant flows, and hollow lines indicate refrigerant flow paths through which decompressed refrigerant flows. In addition, dashed lines in the refrigerant circuit 10 indicate refrigerant flow paths through which refrigerant does not flow.

[0015] 1 shows an example of the configuration of a vehicle air conditioner 1 according to an embodiment of the present invention. The configuration shown here is merely an example, and the present invention is not limited to a specific configuration.

[0016] 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 cabin, which are arranged along a refrigerant flow path. The indoor heat exchangers 21 and 22 are provided to exchange heat between the refrigerant and air flowing through the air conditioning unit 20, and the external heat exchanger 11 is provided to exchange heat between the refrigerant and outside air outside the vehicle cabin. The indoor heat exchanger 21 is used to heat the air, and the indoor heat exchanger 22 is used to cool the air. A refrigerant pressure sensor 44B and a refrigerant temperature sensor 43B are provided immediately downstream of the indoor heat exchanger 21 to detect an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) and an outlet refrigerant temperature Tc (high-pressure side refrigerant temperature), respectively, of the indoor heat exchanger 21.

[0017] The compressor 2 compresses the refrigerant and circulates it within the refrigerant circuit 10. The refrigerant compressed by the compressor 2 is reduced to a required pressure by passing through an appropriately selected refrigerant flow path, for example, a first pressure reduction section V1, a second pressure reduction section V2, a third pressure reduction section V3, and a fourth pressure reduction section V4, which are expansion valves. The refrigerant circuit 10 is provided with 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.

[0018] An accumulator 16 that recovers liquid refrigerant and separates the refrigerant into gas and liquid is provided immediately upstream of the compressor 2 in the refrigerant circuit 10. A refrigerant pressure sensor 44A that detects a suction refrigerant pressure Ps (low-pressure side refrigerant pressure) that is suctioned into the compressor 2 and a refrigerant temperature sensor 43A that detects a suction refrigerant temperature Ts (low-pressure side refrigerant temperature) are provided between the accumulator 16 and the compressor 2.

[0019] As described above, the air conditioning unit 20 includes the indoor heat exchangers 21 and 22 therein, a blower 23 that introduces air into the unit from inside or outside the vehicle cabin, and an air damper 24 that adjusts the proportion of the air introduced by the blower 23 that passes through the indoor heat exchanger 21. The air conditioning unit 20 also includes an air damper 25 that is provided upstream of the blower 23 in the air inflow direction and adjusts the proportion of air inside the vehicle cabin (inside air) and air outside the vehicle cabin (outside air) that is introduced into the air conditioning unit 20.

[0020] In the air conditioning unit 20, air introduced by the blower 23 passes through the indoor heat exchangers 21 and 22 before being blown into the vehicle cabin. When the air damper 24 shown in Fig. 1 is fully open, the air introduced by the blower 23 passes through the indoor heat exchanger 22 and then the indoor heat exchanger 21 before being blown into the vehicle cabin. When the air damper 24 is fully closed, the inlet side of the indoor heat exchanger 21 is closed, and the air introduced by the blower 23 passes only through the indoor heat exchanger 22 before being blown into the vehicle cabin.

[0021] In the air conditioning unit 20, either outside air or inside air can be taken in by selectively closing the air inlet 25A leading to the outside or the air inlet 25B leading to the inside of the room using the air damper 25. Also, in the air conditioning unit 20, the inside air or outside air can be taken in at a desired ratio from both the air inlet 25A and the air inlet 25B by, for example, positioning the air damper 25 at a desired position between the air inlet 25A and the air inlet 25B.

[0022] Although the above-described external heat exchanger 11 and indoor heat exchangers 21, 22 have been described as examples in which the refrigerant directly exchanges heat with the air, the refrigerant may indirectly exchange heat with the air via a heat medium that has exchanged heat with the refrigerant. That is, the refrigerant may absorb heat from the air via the heat medium, or the refrigerant may release heat to the air via the heat medium.

[0023] As shown in Fig. 1, the vehicle air conditioner 1 includes a heat medium circuit 30. The heat medium circuit 30 circulates a heat medium using a circulation pump 31, heats the heat medium using a heater (ECH: Electric Coolant Heater) 32, and recovers waste heat from a temperature-controlled object such as a battery using a temperature-controlled object heat exchanger 33. The refrigerant circuit 10 and the heat medium circuit 30 are provided with a refrigerant-heat medium heat exchanger 34 that exchanges heat between the refrigerant and the heat medium via 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 needed.

[0024] 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 conditioning unit 20, and the heat medium circuit 30 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.

[0025] The sensor section 40 that inputs detection signals to the control device 100 includes, for example, an outside air sensor 41 that detects outside air conditions such as the outside air temperature Tam and 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 cabin, an air outlet temperature sensor 46 that detects the air outlet temperature of the air conditioning unit 20, and an inside air sensor 47 that detects the state of the vehicle cabin such as the inside air temperature and inside air humidity.

[0026] In particular, the refrigerant temperature sensor 43 includes a refrigerant temperature sensor 43A that detects the intake refrigerant temperature Ts (low-pressure side refrigerant temperature) sucked into the compressor 2, and a refrigerant temperature sensor 43B that detects the outlet refrigerant temperature Tc (high-pressure side refrigerant temperature) of the indoor heat exchanger 21 (see Figure 1).

[0027] The refrigerant pressure sensor 44 also includes a refrigerant pressure sensor 44A that detects a suction refrigerant pressure Ps (low-pressure side refrigerant pressure) sucked into the compressor 2, and a refrigerant pressure sensor 44B that detects an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) of the indoor heat exchanger 21 (see FIG. 1). These sensors are just examples, and the sensor unit 40 is provided with various sensors that detect information required for the control device 100 to perform various controls.

[0028] The control devices of the control device 100 are the compressor 2, the first pressure reduction section V1, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valves 12 and 13 in the refrigerant circuit 10, the blower 23, the air dampers 24 and 25 in the air conditioning unit 20, and the circulation pump 31 in the heat medium circuit 30. The control device 100 also controls the vehicle air conditioner 1 according to the processing results of the control device 100. The vehicle air conditioner 1 can execute various operating modes using the control device 100, including an endothermic heating mode in which the refrigerant is caused to absorb heat in the external heat exchanger 11, and a hot gas heating mode in which the refrigerant compressed by the compressor 2 is caused to release heat in the indoor heat exchanger 21 without the refrigerant absorbing heat in the external heat exchanger 11, thereby heating the vehicle cabin.

[0029] [Configuration of Control Device in Electric Vehicle (EV)] As shown in Fig. 3 , the control device 100 provided in the vehicle air conditioner 1 is configured as a single ECU connected to various ECUs (Electronic Control Units) that control the electric vehicle EV via an in-vehicle network L. 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, and the like, and each piece of hardware is connected to one another via a bus 106.

[0030] The CPU 101 controls 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 storage device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM).

[0031] For example, RAM 103 functions as a work area used by CPU 101 when executing a program. Input / output I / F 104 is connected to various sensors and monitors installed in the EV, and inputs data to CPU 101 and outputs data processed by CPU 101. In-vehicle communication I / F 105 is connected to an in-vehicle network L, and controls data transmission and reception with other ECUs set in the EV.

[0032] The control device 100 receives data on the surrounding environment or data on the driving status of the EV via the input / output I / F 104 and the in-vehicle I / F 105, and controls the above-mentioned vehicle air conditioning device 1 using a program executed by the CPU 101.

[0033] The EV is equipped with a battery B. The battery B is charged by connecting a charger plug PS to a 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.

[0034] [Hot gas heating mode] At extremely low temperatures, it is difficult for the external heat exchanger 11 to absorb heat, so the hot gas heating mode is used. The hot gas heating mode is an operation mode in which the refrigerant compressed by the compressor 2 is partially or entirely dissipated in the indoor heat exchanger 21 to heat the vehicle cabin without absorbing heat in the refrigerant in the external heat exchanger 11. In other words, the hot gas heating mode is an operation mode in which the work load of the compressor 2 is utilized to heat the blown air in the indoor heat exchanger 21.

[0035] The operation of the refrigerant circuit 10 in the hot gas heating mode will be described with reference to Figure 4. In this operation, part of the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 and the flow switching valve 12, is decompressed in the third pressure reduction section V3 to become a low-pressure refrigerant, passes through the refrigerant heat medium heat exchanger 34, is separated into gas and liquid in the accumulator 16, and returns to the compressor 2. At this time, in the refrigerant circuit 10, the first pressure reduction section V1 is fully closed, so that refrigerant does not flow to the external heat exchanger 11. In addition, the fourth pressure reduction section V4 is fully closed, so that refrigerant does not flow to the indoor heat exchanger 22.

[0036] The refrigerant circuit 10 has a hot gas bypass 10V that reduces the pressure of at least a portion 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. In the hot gas bypass 10V, a portion of the high-temperature, high-pressure refrigerant is branched off at a branch point P1 immediately downstream of the compressor 2, reduced in pressure at a second pressure reduction section V2, and merged with the low-pressure refrigerant reduced in pressure at a third pressure reduction section V3 at a junction point P2 immediately upstream of the accumulator 16.

[0037] By providing the hot gas bypass 10V, the liquid refrigerant condensed by heat release in the indoor heat exchanger 21 is mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant that can be returned to the compressor 2. In addition, by increasing the flow rate of the refrigerant flowing through the hot gas bypass 10V, the amount of heat release in the indoor heat exchanger 21 can be suppressed, and by opening and closing the second pressure reduction section V2 to adjust the flow rate of the refrigerant flowing through the hot gas bypass 10V, it is possible to maintain a balance between the amount of heat release Qout (energy released by the refrigerant) of the refrigerant circuit 10 and the amount of heat input Qin (energy acquired by the refrigerant) to the compressor 2. In other words, the second pressure reduction section V2 functions as a flow rate adjustment section that adjusts the flow rate of the refrigerant flowing through the hot gas bypass 10V.

[0038] In the hot gas heating mode, the refrigerant flowing through the refrigerant circuit 10 is decompressed in the third decompression section V3 in the flow path that passes through the indoor heat exchanger 21, so that the refrigerant becomes high-pressure refrigerant upstream and low-pressure refrigerant downstream. In this case, it is important to maintain heating capacity that heat exchange does not occur in the refrigerant-heat medium heat exchanger 34 in the low-pressure flow path. In the air conditioning unit 20, air introduced by the blower 23 is heated by heat dissipated in the indoor heat exchanger 21 and then blown into the vehicle cabin.

[0039] [Endothermic heating mode] In the endothermic heating mode, the refrigerant circuit 10 obtains a heat source for heating by causing the refrigerant to absorb heat from the outside air, which is the heat absorption target, by flowing the refrigerant through the external heat exchanger 11 as follows: The flow of refrigerant through the refrigerant circuit 10 in the endothermic heating mode is not shown in the drawings.

[0040] In the endothermic heating mode, 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 are fully closed in the refrigerant circuit 10. Meanwhile, the flow path switching valve 13 is fully open, and the first pressure reducing section V1 is open.

[0041] In the endothermic heating mode, the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 in the air conditioning unit 20 and is depressurized in the first depressurization section V1. The low-pressure refrigerant passes through the external heat exchanger 11 and passes through the flow path switching valve 13, the check valve 14, and the accumulator 16 before being returned to the compressor 2. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the indoor heat exchanger 21, is depressurized in the first depressurization section V1 to become low-pressure refrigerant, absorbs heat and evaporates in the external heat exchanger 11, and returns to the compressor 2. In the air conditioning unit 20, air introduced by the blower 23 is heated by the heat released in the indoor heat exchanger 21 and is blown into the vehicle cabin.

[0042] [Control processing by the control device when the heating load increases] Below, we will explain the control by the control device 100 when heating the vehicle cabin in the vehicle air conditioning device 1 of this embodiment, particularly the control when the heating load HL increases while the hot gas heating mode is being executed.

[0043] When heating the vehicle interior using the vehicle air conditioning system 1, the control device 100 executes either the endothermic heating mode or the hot gas heating mode depending on the external environment, such as the outside air temperature Tam, the set temperature Tset, etc. The hot gas heating mode has a higher heating capacity than the endothermic heating mode, so the control device 100 normally executes the endothermic heating mode when the outside air temperature Tam is at or above a predetermined temperature (for example, −10° C.), and executes the hot gas heating mode when the outside air temperature Tam is below the predetermined temperature, that is, in an extremely low temperature environment.

[0044] When the hot gas heating mode is activated, the control device 100 drives the compressor 2 at the maximum rotation speed so that the amount of heat input to the refrigerant in the compressor 2 is as large as possible, in order to make the high-pressure side refrigerant pressure (e.g., outlet refrigerant pressure Pci) reach a target value. After that, when the high-pressure side refrigerant pressure reaches the target value (stable period), the control device 100 controls each component of the vehicle air conditioner 1 so that the amount of heat input Qin to the compressor 2 and the amount of heat released Qout from the indoor heat exchanger 21 are approximately equal. This allows the hot gas heating mode to continue stably.

[0045] Here, when the flow rate of the refrigerant flowing into the indoor heat exchanger 21 is constant, the amount of heat radiation Qout in the indoor heat exchanger 21 varies depending on the temperature and air flow rate Af of the air passing through the indoor heat exchanger 21.

[0046] (Regarding the Temperature of Air Passing Through the Interior Heat Exchanger 21) As described above, the hot gas heating mode is used in an extremely low-temperature environment where the outside air temperature Tam is below a predetermined temperature. Therefore, if a large amount of outside air is taken into the vehicle cabin, it may be difficult to maintain the desired temperature inside the vehicle cabin. On the other hand, if only inside air is circulated inside the vehicle cabin, the carbon dioxide concentration inside the vehicle cabin will increase. Therefore, when the temperature inside the vehicle cabin is maintained at approximately the target temperature (the stable period described above), the control device 100 controls the air damper 25 to achieve a predetermined fixed ratio (e.g., 30% outside air, 70% inside air), so that the temperature of the air taken into the air conditioning unit 20 is within a certain temperature range.

[0047] (Regarding the Air Volume Af Passing Through the Indoor Heat Exchanger 21) When the control device 100 predicts an increase in the heating load HL or determines that the heating load HL has increased, the control device 100 fully opens the air damper 24 and controls the blower 23 to pass all of the air taken into the air conditioning unit 20 through the indoor heat exchanger 21 in order to raise the target air outlet temperature TAO into the vehicle cabin. Therefore, the air volume Af passing through the indoor heat exchanger 21 depends on the driving state of the blower 23. The greater the air volume blown by the blower 23, the greater the air volume Af passing through the indoor heat exchanger 21 and the heat radiation amount Qout in the indoor heat exchanger 21. In other words, when the flow rate of refrigerant passing through the indoor heat exchanger 21 is constant, driving the blower 23 at the maximum rotation speed maximizes the air volume Af and the heat radiation amount Qout in the indoor heat exchanger 21.

[0048] Hereinafter, the control performed by the control device 100 of the vehicle air conditioner 1 according to this embodiment when the heating load HL increases while the hot gas heating mode is being executed will be described with reference to the flowchart of FIG.

[0049] In the vehicle air conditioning system 1, when the hot gas heating mode is being executed and is in a stable state, the control device 100 monitors fluctuations in the heating load HL to maintain a stable operating state of the hot gas heating mode.

[0050] Fluctuations in the heating load HL occur, for example, in the following cases: when the set temperature Tset is changed by the user, or when an external disturbance occurs, such as when a traveling vehicle exits a tunnel, causing a sudden drop in the temperature of the outside air taken in by the air conditioning unit 20, and the control device 100 changes the target blow-out temperature TAO to maintain the temperature inside the vehicle cabin.

[0051] When the control device 100 determines that the heating load HL has increased (step S11), it calculates the target heating capacity TGQ required in accordance with the increased heating load HL (step S12).

[0052] Based on the target heating capacity TGQ, the control device 100 calculates the heat input Qin required for the compressor 2 and the heat radiation amount Qout in the indoor heat exchanger 21 that can maintain a balance with the heat input Qin. Furthermore, the control device 100 calculates the target rotation speed TGNC of the compressor 2 that is required to obtain the heat input Qin and the air volume AFO that can obtain the target outlet temperature TAO while ensuring the heat radiation amount Qout (step S13).

[0053] The control device 100 determines whether the current air volume Af is equal to the air volume AFO calculated in step S13, i.e., whether the current air volume Af is insufficient compared to the air volume AFO (step S14). If the current air volume Af is equal to or greater than the air volume AFO (NO in step S14), the control device 100 controls the rotation speed of the compressor 2 to the target rotation speed TGNC calculated in step S13 (step S19).

[0054] On the other hand, if the current air volume Af is insufficient compared to the air volume AFO (YES in step S14), it is determined whether the current air volume Af is the maximum air volume Af_Max in the indoor heat exchanger 21, i.e., whether the blower 23 is operating at the maximum rotation speed (step S15).

[0055] If the current air volume Af is not the maximum air volume Af_Max in the indoor heat exchanger 21 (NO in step S15), that is, if the blower 23 is operating at a rotation speed lower than the maximum rotation speed, the rotation speed of the blower 23 is increased to increase the amount of air sent by the blower 23 to the indoor heat exchanger 21 (step S17). This increases the air volume Af in the indoor heat exchanger 21.

[0056] If the current air volume Af is the maximum air volume Af_Max in the indoor heat exchanger 21 (YES in step S15), that is, if the blower 23 is already operating at the maximum rotation speed, the air damper 25 is driven to increase the proportion of outside air in the air taken into the air conditioning unit 20 (step S16). The control device 100 controls the air damper 25 so that the proportion of outside air is 40% and the proportion of inside air is 60%, for example.

[0057] In step S18, the control device 100 determines whether the heat radiation amount Qout calculated in step S13 has been secured by performing the above process, and if the heat radiation amount Qout is insufficient (NO in step S18), the control device 100 returns to step S15 and repeats the above process. On the other hand, if the heat radiation amount Qout has been secured (YES in step S18), the control device 100 controls the rotation speed of the compressor 2 to the target rotation speed TGNC calculated in step S13 (step S19).

[0058] In this way, in the vehicle air conditioner 1 according to this embodiment, when the heating load HL increases in the hot gas heating mode, the heat radiation amount Qout required in response to the increase in the heating load HL can be secured. That is, when the air volume Af in the indoor heat exchanger 21 is insufficient, the control device 100 increases the air volume Af by increasing the rotation speed of the blower 23, thereby increasing the heat radiation amount Qout. On the other hand, when the blower 23 is operating at the maximum rotation speed and the air volume Af cannot be increased, the air damper 25 is driven to increase the proportion of outside air, thereby lowering the temperature of the air passing through the indoor heat exchanger 21 and increasing the heat radiation amount Qout.

[0059] This ensures the required heat input Qin as the heating load HL increases and the heat dissipation Qout required to maintain a balance with the heat input Qin. Therefore, the range within which the target rotational speed TGNC of the compressor 2 can be increased while stably continuing the hot gas heating mode, thereby achieving a desired outlet temperature and improving passenger comfort.

[0060] (Variant) In the above example, the processing when the control device 100 determines that the heating load HL has increased was described. However, for example, if an increase in the heating load HL is predicted as follows, the comfort of the occupants can be improved by performing the above processing in advance.

[0061] The control device 100 acquires the planned driving route and external environmental information along the driving route from an ECU that controls the navigation system and other ECUs that manage and control information such as weather information, via the in-vehicle network L. The external environmental information includes information about the surrounding environment, such as tunnels along the driving route, and outside air conditions such as outside temperature and humidity, derived from weather information along the driving route.

[0062] 5, when the control device 100 predicts that the heating load HL will increase, the control device 100 can control the vehicle air conditioner 1 before the heating load HL changes, thereby improving the comfort of the occupants. Note that, during the above processing, for example, by gradually or stepwise controlling the rotation speed of the blower 23, driving the air damper 25, and controlling the rotation speed of the compressor 2 in order to ensure the heat radiation amount Qout, the comfort of the occupants can be further improved.

[0063] As described above, according to this embodiment, the required amount of heat dissipation is ensured as the heating load increases, and the desired blow-out temperature is achieved while the hot gas heating mode is stably continued, thereby improving the comfort of the occupants.

[0064] The embodiments of the present invention have been described above in detail with reference to the drawings, but the specific configurations are not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.

[0065] 1: Vehicle air conditioning device, 2: Compressor, 10: Refrigerant circuit, 10V: Hot gas bypass, 11: External heat exchanger, 12, 13: Flow path switching valve, 14, 15: Check valve, 16: Accumulator, 20: Air conditioning unit, 21, 22: Indoor heat exchanger, 23: Blower, 24, 25: Air damper, 25A, 25B: Air inlet, 30: Heat medium circuit, 31: Circulation pump, 33: Temperature-controlled heat exchanger, 34: Refrigerant heat medium heat exchanger, 34A, 34B: Flow path, 40: Sensor unit, 41: Outside air sensor, 42: Compressor current sensor, 43, 43A, 43B: Refrigerant temperature sensor, 44, 44A, 44B: Refrigerant pressure sensor, 45: Occupant sensor, 46: Outlet air temperature sensor, 47: Inside air sensor, 60: Input signal, 100: Control device

Claims

1. A vehicle air conditioner comprising: a refrigerant circuit including a compressor, an indoor heat exchange unit, an external heat exchange unit, and a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor without passing through the indoor heat exchange unit and the external heat exchange unit, and returns the refrigerant to the compressor; an air conditioning unit in which the indoor heat exchange unit is disposed, and which has an air damper that adjusts the ratio of inside and outside air to be introduced into the interior, and a blower that blows the introduced air; and a control device that controls the refrigerant circuit and the air conditioning unit, and is capable of executing a hot gas heating mode in which a portion of the refrigerant compressed by the compressor flows through the hot gas bypass and is returned to the compressor, and the remainder dissipates heat in the indoor heat exchange unit, wherein the control device controls the compressor to expand the increasing range of the target rotation speed when it is determined that the heating load has increased while the hot gas heating mode is being executed.

2. A vehicle air conditioning system comprising: a refrigerant circuit including a compressor, an indoor heat exchange unit, an external heat exchange unit, and a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor without passing through the indoor heat exchange unit and the external heat exchange unit, and returns the refrigerant to the compressor; an air conditioning unit in which the indoor heat exchange unit is disposed, and which has an air damper that adjusts the ratio of inside and outside air to be introduced into the interior, and a blower that blows the introduced air; and a control device that controls the refrigerant circuit and the air conditioning unit, and is capable of executing a hot gas heating mode in which a portion of the refrigerant compressed by the compressor flows through the hot gas bypass and returns it to the compressor, and the remainder dissipates heat in the indoor heat exchange unit, wherein the control device acquires external environment information that indicates the external environment on a planned driving route during the hot gas heating mode, and controls the compressor to expand the increasing range of the target rotation speed when it is predicted that the heating load will increase based on the external environment information.

3. A vehicle air conditioning system as described in claim 1 or claim 2, wherein the control device expands the rising range by controlling the amount of heat dissipation in the indoor heat exchange section to increase in accordance with a target rotation speed of the compressor based on an increase in the heating load.

4. An air conditioning system for a vehicle as described in claim 3, wherein the control device increases the amount of air blown by the blower to the indoor heat exchange section, and when the amount of air blown by the blower is at an upper limit value, controls the air damper to increase the proportion of outside air introduced into the air conditioning unit.

Images