Vehicle air conditioner

Abstract

To improve comfort of an occupant by achieving a desired blowout temperature while ensuring a heat release amount required with an increase in heating load and stably continuing a hot-gas heating mode.SOLUTION: A vehicle air conditioner comprises a refrigerant circuit, an air conditioning unit, and a controller for controlling the refrigerant circuit and the air conditioning unit. In the vehicle air conditioner, it is possible to execute a hot-gas heating mode of returning part of a refrigerant compressed by a compressor to the compressor through a bypass and heating a cabin by heat released by the remaining refrigerant. During execution of the hot-gas heating mode, when it is determined that a heating load has increased, control is performed so as to expand an increase range of a target rotation speed of the compressor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air conditioner for a vehicle. [Background technology]

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

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

[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 vehicle cabin in an indoor heat exchanger, then decompressed and returned to the compressor without passing through an external heat exchanger. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-46604 A Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned hot gas heating mode is an operation mode in which the heat generated by the work of the compressor is used to heat the blown air, and the amount of work (amount of heat input) of the compressor becomes the air heating capacity (heat dissipation capacity) of the indoor heat exchanger. Therefore, in the vehicle air conditioner, in order to stably operate 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 in the indoor heat exchanger.

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

[0008] Therefore, for example, when the heating load increases while the blower is operating at the maximum rotation speed, the heat input to the compressor is increased, but the heat dissipation in the indoor heat exchanger cannot be increased, so the heat input becomes large relative to the heat dissipation, and the balance between the heat input and heat dissipation cannot be maintained. In this case, the pressure and temperature of the refrigerant on the intake side (low pressure side) of the compressor rise, and accordingly the pressure and temperature of the refrigerant on the discharge side (high pressure side) also rise, so that the pressure of the refrigerant on the discharge side (high pressure side) exceeds the upper limit, and the hot gas heating mode cannot operate stably, and the vehicle air conditioner may stop.

[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 the heating load, i.e., the blowing temperature cannot be raised to the desired temperature.

[0010] The present invention has been made in consideration of these circumstances, and has as its objective to achieve the desired blowing 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. [Means for solving the problem]

[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 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, 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 controls the vehicle air conditioning system to expand the increase range of the target rotation speed of the compressor when it is determined that the heating load has increased while the hot gas heating mode is being executed. Effect of the Invention

[0012] According to the present invention, it is possible to achieve the desired blowing 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 the occupants. [Brief description of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram showing an example of a system configuration of a vehicle air conditioner according to an embodiment of the present invention; [Diagram 2] 1 is an explanatory diagram showing a control device for a vehicle air conditioner according to an embodiment of the present invention; [Diagram 3] 1 is a diagram showing the configuration of a control device and the like in an electric vehicle (EV) according to an embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram showing an operation of the refrigerant circuit in a hot gas heating mode in the vehicle air conditioning system according to the embodiment of the present invention. [Diagram 5]5 is a flowchart showing a process flow when a heating load increases while a hot gas heating mode is being executed in the vehicle air conditioning device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 functions, and duplicated descriptions in each drawing will be omitted as appropriate. In the drawings, the thick black lines in the refrigerant circuit 10 indicate refrigerant flow paths through which high-pressure refrigerant flows, and the outline lines indicate refrigerant flow paths through which refrigerant flows after decompression. In addition, the dashed lines in the refrigerant circuit 10 indicate refrigerant flow paths through which refrigerant does not flow.

[0015] [Refrigerant circuit configuration, etc.] 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 one example, and the present invention is not particularly 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 for heat exchange between the air flowing through the air conditioning unit 20 and the refrigerant, and the external heat exchanger 11 is provided for heat exchange between the outside air and the refrigerant outside the vehicle cabin. The indoor heat exchanger 21 is for heating the air, and the indoor heat exchanger 22 is for cooling the air. A refrigerant pressure sensor 44B for detecting an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) and a refrigerant temperature sensor 43B for detecting an outlet refrigerant temperature Tc (high-pressure side refrigerant temperature) from the indoor heat exchanger 21 are provided immediately downstream of the indoor heat exchanger 21.

[0017] The compressor 2 compresses the refrigerant and circulates it through a refrigerant circuit 10. The refrigerant compressed by the compressor 2 is reduced in pressure to a required level by passing through 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, for example, expansion valves, in an appropriately selected refrigerant flow path. 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) sucked 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 is equipped with the indoor heat exchangers 21, 22 therein, as well as the blower 23 that introduces air into the interior from inside or outside the vehicle cabin, and the air damper 24 that adjusts the ratio 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 ratio of the air inside the vehicle cabin (indoor air) and the air outside the vehicle cabin (outdoor air) that are 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, 22 and is 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 and is blown into the vehicle cabin. When the air damper 24 is fully closed, the inlet 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 cabin.

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

[0022] Although the above-mentioned external heat exchanger 11 and indoor heat exchangers 21, 22 are described as examples in which the refrigerant and air directly exchange heat, the refrigerant and air may indirectly exchange heat 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 dissipate 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 the 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 control object such as a battery using a temperature control 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 in 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.

[0024] [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 conditioning 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 section 40.

[0025] The sensor section 40, which inputs detection signals to the control device 100, includes, for example, an outside air sensor 41 which detects outside air conditions such as the outside air temperature Tam and outside air humidity, a compressor current sensor 42 for detecting the power consumption (energy consumption) of the compressor 2, a refrigerant temperature sensor 43 and a refrigerant pressure sensor 44 which detect the state of the refrigerant, an occupant sensor 45 which detects the presence or absence of an occupant in the vehicle cabin, an air outlet temperature sensor 46 which detects the air outlet temperature of the air conditioning unit 20, and an inside air sensor 47 which detects conditions inside 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 merely examples, and various sensors that detect information required when the control device 100 performs various controls are provided as the sensor unit 40.

[0028] The control targets of the control device 100 are the compressor 2, the first pressure reducing section V1, the second pressure reducing section V2, the third pressure reducing section V3, the fourth pressure reducing 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 operation modes by the control device 100, including a heat absorbing 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 dissipate heat in the indoor heat exchanger 21 without the refrigerant absorbing heat in the external heat exchanger 11 to heat the vehicle interior.

[0029] [Configuration of control device in electric vehicle (EV)] 3, the control device 100 provided in the vehicle air conditioner 1 is configured as one 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 each other via a bus 106.

[0030] The CPU 101 executes various programs stored in the ROM 102 to control the control device 100. 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 DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory).

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

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

[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 is not allowed to absorb heat in the external heat exchanger 11, and part or all of the refrigerant compressed by the compressor 2 is caused to dissipate heat in the indoor heat exchanger 21 to heat the vehicle cabin. In other words, the hot gas heating mode is an operation mode in which the work load in the compressor 2 is used 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 Fig. 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 path switching valve 12, is depressurized 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 the refrigerant does not flow to the external heat exchanger 11. Also, the fourth pressure reduction section V4 is fully closed, so that the 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 radiation in the indoor heat exchanger 21 can be mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant, which can then 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 radiation 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, the balance between the amount of heat radiation (energy released by the refrigerant) Qout of the refrigerant circuit 10 and the amount of heat input (energy acquired by the refrigerant) Qin to the compressor 2 can be maintained. 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 upstream of that section becomes a high-pressure refrigerant and the refrigerant downstream of that section becomes a low-pressure refrigerant. At this time, it is important in order to maintain the heating capacity that heat exchange is not performed in the refrigerant-heat medium heat exchanger 34 in the low-pressure side flow path. 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 is blown into the vehicle cabin.

[0039] [Endothermic heating mode] In the endothermic heating mode, the refrigerant in the refrigerant circuit 10 is caused to flow through the external heat exchanger 11 as described below, so that the refrigerant absorbs heat from the outside air, which is the heat absorption target, to obtain a heat source for heating. Note that the flow of the refrigerant in the refrigerant circuit 10 in the endothermic heating mode is not shown in the drawings.

[0040] In the refrigerant circuit 10 in the endothermic heating mode, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valve 12 are fully closed. On the other hand, the flow path switching valve 13 is fully open, and the first pressure reduction 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, and 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 depressurized in the first depressurization section V1 to become a 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, the 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 process when heating load increases using a control device] Hereinafter, the control by the control device 100 when heating the vehicle cabin in the vehicle air conditioner 1 according to this embodiment, in particular the control when the heating load HL increases while the hot gas heating mode is being executed, will be described.

[0043] When the vehicle air conditioner 1 heats the vehicle interior, 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. Since the hot gas heating mode has a higher heating capacity than the endothermic heating mode, the control device 100 normally executes the endothermic heating mode when the outside air temperature Tam is equal to or higher than a predetermined temperature (e.g., -10°C), and executes the hot gas heating mode when the outside air temperature Tam is an extremely low temperature environment below the predetermined temperature.

[0044] When the hot gas heating mode is started, 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., the outlet refrigerant pressure Pci) reach a target value. Thereafter, 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 in the compressor 2 and the amount of heat dissipation Qout in the indoor heat exchanger 21 are approximately equal. This allows the hot gas heating mode to continue stably.

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

[0046] (Regarding the temperature of air passing through the indoor 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, so taking in a large amount of outside air into the vehicle cabin can make it difficult to maintain the interior temperature at a desired level, while circulating only inside air into the vehicle cabin increases the carbon dioxide concentration in the vehicle cabin. Therefore, when the temperature inside the vehicle cabin is maintained at approximately the target temperature (the above-mentioned stable period), 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 volume Af of air 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, in order to raise the target blown temperature TAO into the vehicle cabin, the control device 100 controls the air damper 24 to be fully opened so that all of the air taken into the air conditioning unit 20 is passed through the indoor heat exchanger 21 by the blower 23. Therefore, the air volume Af passing through the indoor heat exchanger 21 depends on the driving state of the blower 23, and the larger the air volume sent by the blower 23, the larger the air volume Af passing through the indoor heat exchanger 21 and the heat radiation amount Qout in the indoor heat exchanger 21 become. In other words, when the flow rate of the refrigerant passing through the indoor heat exchanger 21 is constant, the air volume Af and the heat radiation amount Qout in the indoor heat exchanger 21 become maximum by driving the blower 23 at the maximum rotation speed.

[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 conditioner 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 in order to maintain a stable operating state in 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 a disturbance occurs, such as when a traveling vehicle leaves a tunnel and the temperature of the outside air taken into the air conditioning unit 20 drops suddenly, causing the control device 100 to change the target blowing 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 a target heating capacity TGQ required according to 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 the 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 discharge temperature TAO while ensuring the heat radiation amount Qout (step S13).

[0053] The control device 100 determines whether the current air volume Af is the air volume AFO calculated in step S13, that is, whether the current air volume Af is insufficient with respect 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 relative 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 driven 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 amount of heat radiation Qout calculated in step S13 has been secured by performing the above process, and if the amount of heat radiation 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 amount of heat radiation 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 accordance with 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 heat radiation amount Qout by increasing the rotation speed of the blower 23 to increase the air volume Af. On the other hand, when the blower 23 is driven 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 decreasing the temperature of the air passing through the indoor heat exchanger 21 and increasing the heat radiation amount Qout.

[0059] This makes it possible to secure the required heat input Qin in accordance with an increase in the heating load HL and the heat dissipation Qout for maintaining a balance with the heat input Qin. Therefore, it is possible to expand the range of increase in the target rotation speed TGNC of the compressor 2 while stably continuing the hot gas heating mode, thereby realizing the desired blown air temperature and improving the comfort of the occupants.

[0060] (Modification) In the above example, the processing performed when the control device 100 determines that the heating load HL has increased has been described. However, for example, when an increase in the heating load HL is predicted as described below, 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 environment information on 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 environment information includes surrounding environment information such as tunnels on the driving route, and outside air conditions such as outside temperature and outside humidity from weather information on the driving route.

[0062] 5, when it is predicted 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. In addition, in the above process, 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 blowing temperature is achieved while stably continuing the hot gas heating mode, thereby improving the comfort of the occupants.

[0064] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is 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. [Explanation of symbols]

[0065] 1: vehicle air conditioning system, 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: Heat exchanger to be temperature-controlled 34: refrigerant / heat medium heat exchanger, 34A, 34B: flow path, 40: sensor unit 41: Outdoor air sensor, 42: Compressor current sensor 43, 43A, 43B: refrigerant temperature sensor, 44, 44A, 44B: refrigerant pressure sensor 45: occupant sensor, 46: blower temperature sensor, 47: inside air sensor, 60: input signal 100: Control device

Claims

1. 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 and returns it to 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 exchanger is disposed, the air damper adjusting the ratio of inside and outside air to be introduced into the air conditioning unit, and a blower blowing the introduced air; a control device capable of controlling the refrigerant circuit and the air conditioning unit, and executing a hot gas heating mode in which a part 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 exchanger, The control device includes: An air conditioner for a vehicle, the air conditioner performing control so as to expand an increase range of a target rotation speed of the compressor when it is determined that a heating load has increased while a hot gas heating mode is being executed.

2. 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 and returns it to 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 exchanger is disposed, the air damper adjusting the ratio of inside and outside air to be introduced into the air conditioning unit, and a blower blowing the introduced air; a control device capable of controlling the refrigerant circuit and the air conditioning unit, and executing a hot gas heating mode in which a part 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 exchanger, The control device includes: An air conditioning system for a vehicle, which, while executing a hot gas heating mode, acquires external environment information indicating the external environment along a planned driving route, and, if it is predicted that the heating load will increase based on the external environment information, controls to expand the increase range of the compressor's target rotation speed.

3. The control device includes:

3. The vehicle air conditioning system according to claim 1, wherein the increase range is expanded by controlling the amount of heat dissipated in the indoor heat exchanger to increase in accordance with a target rotation speed of the compressor based on an increase in a heating load.

4. The control device includes: Increasing the amount of air sent to the indoor heat exchange unit by the blower, 4. The vehicle air conditioner according to claim 3, wherein the air damper is controlled so as to increase the proportion of outside air introduced into the air conditioning unit when the amount of air blown by the blower is at an upper limit value.

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