Vehicular air conditioner

Abstract

To provide a vehicular air conditioner configured so that when a target air temperature is increased during hot gas heating operation. a blow-out air temperature can be prevented from decreasing.SOLUTION: In a vehicular air conditioner, a refrigerant circuit has a hot gas bypass that decompresses at least a portion of a refrigerant compressed by a compressor, without going through an external heat exchanger, and returns the refrigerant to the compressor. A control device can execute perform control so that hot gas heating operation by which the refrigerant can be prevented from absorbing heat in the external heat exchanger and heat of the refrigerant compressed by the compressor is radiated in an indoor heat exchanger to heat a vehicle interior is executed. In a case where a target air temperature is changed during the execution of the hot gas heating operation, a restriction mode in which air volumes by an air blower are restricted from being changed is executed, where a temperature difference between a target blow-out air temperature TCO of the indoor heat exchanger calculated based on the target air temperature and a blow-out air temperature Thp of the indoor heat exchanger is above a predetermined threshold α (|TCO-Thp|≥α).SELECTED DRAWING: Figure 8

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 installed in the vehicle have become widespread. A heating mechanism of the vehicle air conditioner installed in such vehicles is known to use a heat pump (refrigerant circuit) as a heat source.

[0003] Vehicle air conditioners using a heat pump make the external heat exchanger function as a heat absorber during heating operation, and obtain a heating heat source from the outside air. Therefore, when the outside temperature becomes extremely low, it becomes difficult to absorb heat from the outside air, and the heating capacity drops significantly. In response to this, there is known a vehicle air conditioner that performs so-called hot gas heating, which does not absorb heat from the outside air, but uses heat generated by the work of the compressor to heat the vehicle interior (for example, Patent Document 1). Because hot gas heating does not absorb heat, it can be used in extremely low temperature environments. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-46604 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the target air temperature for heating is increased during non-hot gas heating operation, the air volume increases and the temperature inside the cabin rises quickly. However, it was found that when the target air temperature for heating is increased during hot heating operation, the outlet temperature may be lowered against the user's will. It was also found that when the target air temperature is lowered, the air volume is reduced and the outlet temperature may be higher against the user's will.

[0006] To prevent a blowing temperature from becoming against a user's will when a target air temperature is changed during hot gas heating operation. [Means for solving the problem]

[0007] In order to solve such problems, one embodiment of the present invention has the following configuration. In a vehicle air conditioner including a refrigerant circuit including a compressor, an indoor heat exchanger, and an external heat exchanger, an air conditioning unit including a blower that has the indoor heat exchanger disposed therein and blows air that flows into a vehicle interior after heat exchange with the indoor heat exchanger, and a control device that controls the refrigerant circuit and the air conditioning unit, the refrigerant circuit has 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 external heat exchanger, and the control device controls the external heat exchanger to reduce the pressure of the refrigerant. The vehicle air conditioning system is capable of controlling to execute a hot gas heating operation in which the refrigerant compressed by the compressor dissipates heat in the indoor heat exchanger to heat the vehicle cabin without absorbing heat, and if a change in the target air temperature occurs during the hot gas heating operation, when the temperature difference between a target outlet air temperature TCO of the indoor heat exchanger calculated based on the target air temperature and the outlet air temperature Thp of the indoor heat exchanger is equal to or greater than a predetermined threshold value α (|TCO-Thp|≧α), the system executes a restriction mode to restrict a change in the air volume of the blower. Effect of the Invention

[0008] According to the present invention, when the target air temperature is changed during hot gas heating operation, it is possible to prevent the air outlet temperature from becoming unwilling to the user. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a refrigerant circuit and the like of an air conditioning device for a vehicle according to an embodiment [Diagram 2] 1 is a 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. 2 is a diagram showing a refrigerant circuit in hot gas heating operation according to an embodiment of the present invention. [Diagram 5] Mollier diagram for hot gas heating operation. [Figure 6] Mollier diagram for excess heat release during hot gas heating operation. [Figure 7] FIG. 4 illustrates a transition to a restricted mode of blower operation according to an embodiment of the present invention. [Figure 8] 3 is a control flow according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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 having the same function, and duplicated descriptions in each drawing will be omitted as appropriate.

[0011] [Refrigerant circuit configuration, etc.] 1 shows the configuration of a refrigerant circuit 10 and the like in a vehicle air conditioner 1 according to an embodiment of the present invention. The configuration shown here is an example, and the present invention is not particularly limited to a specific configuration.

[0012] 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 arranged inside the air conditioning unit 20, and an external heat exchanger 11 arranged outside the vehicle compartment, which are arranged along a refrigerant flow path. The indoor heat exchangers 21 and 22 are provided for heat exchange between the air flowing inside 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 compartment. The indoor heat exchanger 21 is for heating the air, and the indoor heat exchanger 22 is for cooling the air.

[0013] The compressor 2 compresses the refrigerant and circulates it through the 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. An accumulator 16 is provided immediately upstream of the compressor 2 in the refrigerant circuit 10 to recover liquid refrigerant and separate the refrigerant into gas and liquid.

[0014] As described above, the air conditioning unit 20 includes the indoor heat exchangers 21 and 22, and the air introduced from the room or the outside by the blower 23 passes through the indoor heat exchangers 21 and 22 and is blown into the room. The air conditioning unit 20 is provided with an air damper 24. When the air damper 24 shown in FIG. 1 is fully open, the air introduced by the blower 23 passes through both the indoor heat exchangers 21 and 22 and is blown into the room. When the air damper 24 is fully closed, the intake 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 room. Another air damper 25 provided in the air conditioning unit 20 switches the air introduced into the blower 23 between the indoor air and the outdoor air. 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 room to take in air from either one of them. Moreover, by placing the air damper 25 in an intermediate position, air can be taken in from both the air inlet 25A and the air inlet 25B.

[0015] Various sensors, which will be described later, are provided in the vehicle air conditioner 1. In the air conditioning unit 20, a blowing air temperature sensor 461 is provided on the blowing side of the indoor heat exchanger 21. The blowing air temperature sensor 461 is one of the blowing air temperature sensors 46 provided on the blowing side of the air conditioning unit 20 to detect the temperature.

[0016] 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.

[0017] In the embodiment 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.

[0018] [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 (such as an air conditioning instruction signal and a charger connection signal) and detection signals from a sensor section 40.

[0019] The sensor section 40, which inputs detection signals to the control device 100, includes an outside air sensor 41 that detects outside air conditions such as outside air temperature 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, and a blown air temperature sensor 46 that detects the blown air temperature of the air conditioning unit 20 shown in Fig. 1 etc. These sensors are merely examples, and the sensor section 40 is provided with various sensors that detect information necessary for the control device 100 to perform various controls.

[0020] The control targets 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, the flow path switching valve 12, the flow path switching valve 13, etc. in the refrigerant circuit 10, and the blower 23, the air dampers 24, 25, etc. in the air conditioning unit 20. Also, the control targets are the circulation pump 31, etc. in the heat medium circuit 30. The control device 100 can switch between an endothermic heating operation in which heat is absorbed by the refrigerant in the external heat exchanger 11, and a hot gas heating operation in which the refrigerant compressed by the compressor 2 is allowed to dissipate heat in the indoor heat exchanger 21 without absorbing heat into the refrigerant in the external heat exchanger 11, to heat the vehicle interior.

[0021] [Configuration of control device in electric vehicle (EV)] In the embodiment, 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 an electric vehicle (EV) via an in-vehicle network L, as shown in Fig. 3. The control device 100 includes hardware such as a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an input / output I / F (Interface) 104, and an in-vehicle communication I / F (Interface) 105, and the various pieces of hardware are connected to each other via a bus 106.

[0022] 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. The ROM 102 stores the programs executed by the CPU 101, data necessary for the CPU 101 to execute the programs, and the like. The RAM 103 is a main storage device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM). The RAM 103 also functions as a work area used when the CPU 101 executes the programs. The input / output I / F 104 is connected to various sensors and monitors of the sensor unit 40 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.

[0023] The control device 100 controls the above-mentioned vehicle air conditioner 1 by a program executed by the CPU 101 when data related to surrounding environmental information or data related to the driving status of the EV is input via the input / output I / F 104 or the in-vehicle communication I / F 105.

[0024] 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.

[0025] [Endothermic heating operation] Next, the operation of the refrigerant circuit 10 in the normally used endothermic heating operation will be described with reference to Fig. 1. In the refrigerant circuit 10 in the endothermic heating operation, 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.

[0026] In the endothermic heating operation, 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. Then, 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. Then, the pressure is reduced in the first depressurization section V1 to become low-pressure refrigerant, which 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 from the indoor heat exchanger 21 and is blown into the vehicle cabin.

[0027] [Hot gas heating operation] At extremely low temperatures, hot gas heating is used because it is difficult for the external heat exchanger 11 to absorb heat. In hot gas heating operation, the refrigerant compressed by the compressor 2 is partially or entirely dissipated in the indoor heat exchanger 21 to heat the vehicle cabin, without the refrigerant absorbing heat in the external heat exchanger 11.

[0028] The operation of the refrigerant circuit 10 in hot gas heating operation according to the embodiment will be described with reference to Fig. 4. In the figure, the thick black lines in the refrigerant circuit 10 indicate refrigerant flow paths through which high-pressure refrigerant flows, and the outlined lines indicate refrigerant flow paths through which low-pressure refrigerant flows after pressure reduction. Also, the dashed lines in the refrigerant circuit 10 indicate refrigerant flow paths through which no refrigerant flows.

[0029] In the hot gas heating operation in this embodiment, the flow path switching valve 12, the second pressure reduction part V2, and the third pressure reduction part V3 are opened. Then, the high-pressure refrigerant discharged from the compressor 2 branches and flows through two refrigerant flow paths.

[0030] The first refrigerant flow path passes through the indoor heat exchanger 21. As shown in FIG. 4, a part of the high-temperature high-pressure refrigerant discharged from the compressor 2 dissipates heat in the indoor heat exchanger 21, passes through the flow path switching valve 12, and is depressurized in the third pressure reduction section V3 to become a low-pressure refrigerant. The low-pressure refrigerant passes through the refrigerant heat medium heat exchanger 34, undergoes gas-liquid separation in the accumulator 16, and returns to the compressor 2. In the refrigerant circuit 10 during hot gas heating operation, the first pressure reduction section V1 is fully closed, so that no refrigerant flows through the external heat exchanger 11. In addition, the fourth pressure reduction section V4 is fully closed, so that no refrigerant flows through the indoor heat exchanger 22.

[0031] The second refrigerant flow path does not pass through the indoor heat exchanger 21. 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 and reduced in pressure at a second pressure reduction section V2 (hot gas valve). Then, at a junction point P2 immediately upstream of the accumulator 16, the refrigerant is merged with the low-pressure refrigerant reduced in pressure at the third pressure reduction section V3.

[0032] By providing such a hot gas bypass 10V, it becomes possible to mix the liquid refrigerant condensed by heat release in the indoor heat exchanger 21 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 refrigerant flow rate flowing through the hot gas bypass 10V, it is possible to suppress the amount of heat release in the indoor heat exchanger 21, and by adjusting the refrigerant flow rate flowing through the hot gas bypass 10V by opening and closing the second pressure reduction section V2 (hot gas valve), it is possible to maintain a balance between the amount of heat release from the refrigerant circuit 10 and the amount of heat input to the compressor 2.

[0033] During hot gas heating operation, the refrigerant flow in the refrigerant passage passing through the indoor heat exchanger 21 is depressurized in the third depressurization section V3, so that the upstream side becomes a high-pressure side passage through which a high-pressure refrigerant flows, and the downstream side becomes a low-pressure side passage through which a low-pressure refrigerant flows. In the air conditioning unit 20, air introduced by the blower 23 is heated by heat released by the indoor heat exchanger 21 and is blown out into the vehicle cabin.

[0034] Figure 5 shows the thermodynamic cycle during hot gas heating operation in Figure 4 using a Mollier diagram. The horizontal axis shows specific enthalpy h, and the vertical axis shows pressure P. In this embodiment, during hot gas heating operation, two refrigerant flow paths are used, one that passes through the indoor heat exchanger 21 and the flow path switching valve 12 and is depressurized at the third depressurization section V3, and the other that passes through the second depressurization section V2 by the hot gas bypass 10V, as shown in Figure 4.

[0035] In FIG. 5, the thermodynamic cycle during hot gas heating operation is shown by arrows a→b→c→d→a and a→b→dh→a. a→b→c→d→a is a thermodynamic cycle of the refrigerant compressed by the compressor 2, branched at the branch point P1, dissipating heat in the indoor heat exchanger 21, depressurized at the third depressurization section V3, and reaching the junction point P2. a→b→dh→a is a thermodynamic cycle of the refrigerant in the hot gas bypass 10V, in which the refrigerant compressed by the compressor 2 branches at the branch point P1, depressurized at the second depressurization section V2, and reaching the junction point P2. a→b is a compression process, in which the temperature of the refrigerant rises and becomes high at point b. b→c is a condensation process, in which the refrigerant dissipates heat in the indoor heat exchanger 21. c→d and b→dh are expansion processes. The refrigerant at point d and the refrigerant at point dh join at the junction point P2 and reach point a. In the d→a and dh→a processes, heat exchange occurs between the refrigerants.

[0036] During hot gas heating operation, as shown in Figure 5, the relationship between the energy Qin gained by the refrigerant and the energy Qout released from the refrigerant is: energy Qin = energy Qout released. Therefore, the thermodynamic cycle starting from point a returns to point a.

[0037] [Target air temperature change operation] When the target air temperature Tset is changed during hot gas heating operation, the air volume Af of the blower 23 generally increases or decreases. If the air volume Af is too large, there is a possibility of excessive heat dissipation. Also, if the air volume Af is too small, there is a possibility of insufficient heat dissipation. For example, when a user performs an operation to increase the target air temperature Tset in order to increase the temperature inside the cabinet of the vehicle, the vehicle air conditioner 1 emits hot air at a large air volume Af. This may result in excessive heat dissipation of the refrigerant during hot gas heating operation, and the thermodynamic cycle may be reduced. Also, when a user performs an operation to decrease the target air temperature Tset in order to decrease the temperature inside the cabinet of the vehicle, the vehicle air conditioner 1 emits hot air at a small air volume Af. This may result in insufficient heat dissipation of the refrigerant during hot gas heating operation, and the thermodynamic cycle may be expanded. Even if the target air temperature Tset is decreased, the temperature of the hot air increases if the thermodynamic cycle is expanded.

[0038] [Excessive heat release during hot gas heating operation] If the target outlet air temperature TCO is raised during hot gas heating operation, the air volume also increases, making it easier for excessive heat to be released. If excessive heat is released in the indoor heat exchanger 21, the thermodynamic cycle is reduced. Figure 6 shows the thermodynamic cycle in the case of excessive heat release. After the compression process from a1 to b1, if excessive heat is released in the condensation process of the indoor heat exchanger 21, it transitions from b1 to c1. The specific enthalpy h at point c1 is smaller than the specific enthalpy h at point c in Figure 5. Then, when the refrigerant is depressurized in the third pressure reduction section V3, it reaches point d1. Also, the refrigerant in the hot gas bypass 10V is depressurized in the second pressure reduction section V2 and reaches point dh1. Then, the refrigerants merge at the confluence point P2, heat exchange occurs between the refrigerants, and the refrigerants reach point a2. At point a2, the specific enthalpy h is smaller than at point a1, and the refrigerant is in a low temperature and low pressure state. Furthermore, if the thermodynamic cycle indicated by the thick arrow after the compression stroke from a2 to b2 continues, the specific enthalpy h becomes smaller and the thermodynamic cycle shrinks.

[0039] In hot gas heating operation with excess heat release, the relationship between the energy Qin gained by the refrigerant and the energy Qout released is: energy Qin < energy Qout. Therefore, the thermodynamic cycle starting from point a1 does not return to point a1, and the pressure P and specific enthalpy h gradually decrease to points a2, a3, etc.

[0040] If the thermodynamic cycle is reduced and the refrigerant temperature or pressure falls below a predetermined value, the safety device may be activated and the hot gas heating operation may be stopped. If the safety device is activated, it may take some time for the hot gas heating operation to resume. Even if the hot gas heating operation resumes, it may stop immediately, and the operation may resume and stop repeatedly. This situation may cause discomfort to the passengers.

[0041] During hot gas heating operation, the compressor 2 basically compresses the air at close to its limit, and it is difficult to obtain a large amount of energy by further increasing the rotation speed. In the event of excessive heat dissipation, the refrigerant flow rate to the indoor heat exchanger 21 can be reduced and the amount of heat dissipated from the refrigerant circuit 10 can be reduced by increasing the refrigerant flow rate through the hot gas bypass 10V, for example, by opening the second pressure reduction section V2 (hot gas valve) and throttling the third pressure reduction section V3. However, if the amount of heat dissipation is reduced by reducing the refrigerant flow rate to the indoor heat exchanger 21, the temperature of the air that has undergone heat exchange drops, causing the blown air temperature Thp to drop and resulting in a loss of feeling of warmth.

[0042] [Insufficient heat dissipation during hot gas heating operation] If the air volume decreases due to a decrease in the target outlet air temperature TCO during hot gas heating operation, there is a possibility that heat dissipation from the indoor heat exchanger 21 will be insufficient. If heat dissipation is insufficient, the thermodynamic cycle will expand. If the thermodynamic cycle expands, comfort will deteriorate because the outlet air temperature Thp will not decrease.

[0043] [Transition to restricted mode during hot gas heating operation] Therefore, in an embodiment of the present invention, when the target air temperature Tset is changed during hot gas heating operation, if the temperature difference between the target blown air temperature TCO of the indoor heat exchanger 21 and the blown air temperature Thp of the indoor heat exchanger 21 is equal to or greater than a predetermined threshold value α, a restriction mode is executed to restrict the change in the air volume of the blower 23. The target blown air temperature TCO is calculated based on the target air temperature Tset. In the restriction mode in the embodiment, the air volume Af is maintained as is, but it may also be restricted by reducing the amount of change in the air volume Af or slowing down the rate of change in the air volume.

[0044] An example of transition to the restriction mode during hot gas heating operation by the vehicle air conditioner 1 using the control device 100 will be described with reference to the transition diagram in Fig. 7. The "blower F / B mode" is a normal hot gas heating operation mode, in which the air volume Af by the blower 23 is adjusted by feedforward and feedback. The "blower restriction mode", which is a restriction mode, is a mode in which changes in the air volume Af by the blower 23 are restricted, and in this embodiment, is a mode in which the air volume Af is maintained as is. The "blower restriction mode" may also be a mode in which the amount of change in the air volume Af is restricted to be small, or the rate of change in the air volume is restricted by slowing down.

[0045] The blown air temperature Thp after passing through the indoor heat exchanger 21 is measured by the blown air temperature sensor 461 shown in Fig. 4. In Fig. 7, if the target air temperature Tset is changed during hot gas heating operation in the "blower F / B mode", the temperature difference between the target blown air temperature TCO of the indoor heat exchanger 21 calculated based on the target air temperature Tset and the blown air temperature Thp of the indoor heat exchanger 21 is calculated. If the temperature difference exceeds a predetermined threshold value α (|TCO-Thp|≧α), the mode transitions to the "blower limit mode" as in "1", and the limit mode that limits changes in the air volume of the blower 23 is executed, and the air volume Af is maintained as it is.

[0046] In this embodiment, the restriction mode is executed both when the target blown air temperature TCO is greater than or less than the blown air temperature Thp. When the target blown air temperature TCO is greater than the blown air temperature Thp, the air volume Af does not increase, and excessive heat dissipation from the refrigerant is suppressed. When the target blown air temperature TCO is less than the blown air temperature Thp, the air volume Af does not decrease, and insufficient heat dissipation from the refrigerant is suppressed.

[0047] After transitioning to the "blower limit mode", which is a limit mode, when the temperature difference between the target blown air temperature TCO and the blown air temperature Thp becomes equal to or less than a predetermined release threshold value β (|TCO-Thp|≦β), as in "2", transitioning to the "blower F / B mode" and the limit mode is released. The magnitude relationship between the threshold value α and the release threshold value β is α<β. In this embodiment, the limit mode is released both when the target blown air temperature TCO is larger and smaller than the blown air temperature Thp.

[0048] The above points will be explained using the flow in Fig. 8. In the basic state, the control device 100 executes hot gas heating operation in blower F / B mode. When the target air temperature Tset is increased by the user's operation, the air volume Af of the blower 23 is increased, and when the target air temperature Tset is decreased, the air volume Af is decreased.

[0049] When the target air temperature Tset is changed by a user operation or the like in the basic state (step S1), the control device 100 calculates the target heating capacity TGQ from the target air temperature Tset (step S2). Then, the control device 100 calculates the required air volume Af and the target blown air temperature TCO from the calculated target heating capacity TGQ (step S3). In addition, the blown air temperature Thp is obtained by the blown air temperature sensor 461 (step S4).

[0050] Then, it is determined whether the absolute value of the value obtained by subtracting the blown air temperature Thp from the target blown air temperature TCO is equal to or greater than a threshold value α (step S5). The absolute value of the value obtained by subtracting the blown air temperature Thp from the target blown air temperature TCO is the temperature difference between the target blown air temperature TCO and the blown air temperature Thp. If the absolute value of the value obtained by subtracting the blown air temperature Thp from the target blown air temperature TCO is equal to or greater than the threshold value α (YES), the system enters the "blower limit mode", which is a limit mode, and the change in the air volume is limited (step S6). In this embodiment, since the target air temperature Tset has been changed, the air volume Af should normally be changed, but since the limit mode is in effect, the air volume Af is maintained as is.

[0051] If the absolute value of the difference between the target air temperature TCO and the air temperature Thp is not equal to or greater than the threshold value α (NO) in step S5, the air volume change is permitted (step S9). If the target air temperature Tset is increased in step S1, the air volume Af is increased, and if it is decreased, the air volume Af is decreased.

[0052] On the other hand, even after the mode is switched to the "blower limit mode" in step S6, the blown air temperature Thp is acquired (step S7). Then, it is determined whether the absolute value of the value obtained by subtracting the blown air temperature Thp from the target blown air temperature TCO is equal to or less than the release threshold value β (step S8). The absolute value of the value obtained by subtracting the blown air temperature Thp from the target blown air temperature TCO is the temperature difference between the target blown air temperature TCO and the blown air temperature Thp. If the absolute value of the value obtained by subtracting the blown air temperature Thp from the target blown air temperature TCO is equal to or less than the release threshold value β (YES), a change in the airflow is permitted and the mode becomes "blower F / B mode" (step S9).

[0053] On the other hand, in step S8, if the absolute value of the difference between the target blown air temperature TCO and the blown air temperature Thp is not equal to or less than the release threshold value β (NO), the process returns to step S7 to acquire the blown air temperature Thp. Then, steps S7 and S8 are repeated until step S8 becomes YES.

[0054] In the embodiment, the mode is changed based on the determination using the blown air temperature Thp measured by the blown air temperature sensor 461. However, the mode may be changed based on the determination, for example, by estimating the blown air temperature Thp, which is the temperature of the air after heat exchange in the indoor heat exchanger 21, based on the temperature of the refrigerant temperature sensor 43 provided immediately after the indoor heat exchanger 21 in the refrigerant circuit 10.

[0055] In the embodiment, the temperature difference between the target blown air temperature TCO of the indoor heat exchanger 21 calculated based on the target air temperature Tset and the blown air temperature Thp of the indoor heat exchanger 21 is calculated. If the temperature difference exceeds a predetermined threshold α (|TCO-Thp|≧α), a restriction mode that restricts the change in the air volume of the blower 23 is executed to maintain the air volume Af as it is. If the temperature difference between the target blown air temperature TCO and the blown air temperature Thp becomes equal to or less than a predetermined release threshold β that is smaller than the threshold α (|TCO-Thp|≦β), the restriction mode is released. In this way, control is performed to enter or release the restriction mode in both cases where the target blown air temperature TCO≧blown air temperature Thp and where the target blown air temperature TCO≦blown air temperature Thp.

[0056] However, the above control may be performed only when the target blown air temperature TCO≧the blown air temperature Thp, or only when the target blown air temperature TCO≦the blown air temperature Thp. In these cases, the restriction mode is executed when the temperature difference between the target blown air temperature TCO and the blown air temperature Thp is equal to or greater than the threshold value α, and the restriction mode is released when the temperature difference is equal to or less than the release threshold value β. In the present application, the condition of "above the threshold" includes the condition of exceeding the threshold, and the condition of "below the release threshold" includes the condition of being less than the release threshold.

[0057] Although the embodiments of the present invention have been described in detail above, the specific configuration is not limited to these embodiments, and the present invention includes design changes within the scope of the present invention. The above-mentioned embodiments can be combined by utilizing each other's technologies as long as there are no particular contradictions or problems in the purpose, configuration, etc. [Explanation of symbols]

[0058] 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, 30: Heat medium circuit, 31: Circulation pump, 32: Heater, 33: Temperature control target heat exchanger, 34: Refrigerant heat medium heat exchanger, 24, 25: Air damper, 25A, 25B: Air inlet, 40: sensor unit, 41: outside air sensor, 42: compressor current sensor, 43: refrigerant temperature sensor, 44: refrigerant pressure sensor, 45: occupant sensor, 46: Airflow temperature sensor, 461: Airflow temperature sensor, 100: control device, V1: First pressure reducing section, V2: Second pressure reducing section, V3: Third pressure reducing section, V4: Fourth pressure reducing section P1: Branch point, P2: Junction point, Tset: target air temperature, TGQ: target heating capacity, TCO: target outlet air temperature, Thp: outlet air temperature, air volume: Af, α: threshold, β: release threshold

Claims

1. a refrigerant circuit including a compressor, an indoor heat exchanger, and an external heat exchanger; an air conditioning unit including a blower that has the indoor heat exchanger disposed therein and blows air that flows into a vehicle interior after exchanging heat with the indoor heat exchanger; a control device for controlling the refrigerant circuit and the air conditioning unit, the refrigerant circuit has a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor and returns the refrigerant to the compressor without passing through the external heat exchanger, The control device includes: It is possible to perform control to execute a hot gas heating operation in which the refrigerant compressed by the compressor is caused to radiate heat in the indoor heat exchanger without absorbing heat in the external heat exchanger, and the vehicle interior is heated; When a change occurs in the target air temperature during the hot gas heating operation, and the temperature difference between the target outlet air temperature of the indoor heat exchanger calculated based on the target air temperature and the outlet air temperature of the indoor heat exchanger is equal to or greater than a predetermined threshold value, the vehicle air conditioning system executes a restriction mode that restricts changes in the air volume of the blower.

2. The control device includes:

2. The vehicle air conditioner according to claim 1, wherein the restriction mode is released when a temperature difference between the target blown air temperature and the blown air temperature becomes equal to or smaller than a predetermined release threshold value that is smaller than the threshold value after the restriction mode is entered.

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