Vehicular air conditioner

Abstract

To provide a vehicular air conditioner that can achieve hot gas heating operation by which a thermodynamic cycle is prevented from becoming unstable even if disturbance occurs.SOLUTION: A vehicular air conditioner is provided with: a refrigerant circuit including a compressor, an indoor heat exchanger and an external heat exchanger; an air conditioning unit having the indoor heat exchanger arranged therein and including an air blower that blows air flowing into a vehicle interior after exchanging heat with the indoor heat exchanger; and a control part that controls the refrigerant circuit and the air conditioning unit. The refrigerant circuit has a hot gas bypass that decompresses at least a portion of a refrigerant compressed by the compressor without going through the external heat exchanger and returns the refrigerant to the compressor. The control device can perform control so that hot gas heating operation by which the refrigerant is prevented from absorbing heat in the external heat exchanger and heat of the refrigerant compressed by the compressor is radiated by the indoor heat exchanger to heat a vehicle interior is executed. When it is determined that a temperature of air whose heat is exchanged by the indoor heat exchanger is below a predetermined temperature during the execution of the hot gas heating operation, a regulating mode, in which an upper limit value of air volumes blown by the air blower is lowered, is set.SELECTED DRAWING: Figure 7

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. A heating mechanism for a vehicle air conditioner mounted on 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] Hot gas heating is effective as a heating mechanism in extremely low temperature environments because it does not absorb heat in an external heat exchanger. However, it was found that when disturbances occur, such as a sudden drop in outside temperature or a sudden increase in vehicle speed, the thermodynamic cycle shrinks and becomes unstable, which may activate a safety device and stop the hot gas heating operation.

[0006] An object of the present invention is to realize a hot gas heating operation in which the thermodynamic cycle does not become unstable even when an external disturbance occurs. [Means for solving the problem]

[0007] In order to solve such problems, one embodiment of the present invention has the following configuration. 1. A vehicle air conditioning system comprising: a refrigerant circuit including a compressor, an indoor heat exchanger, and an external heat exchanger; an air conditioning unit including a blower having the indoor heat exchanger disposed therein and blowing air that flows into a vehicle cabin after exchanging heat with the indoor heat exchanger; and 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 it to the compressor without passing through the external heat exchanger. The control device is capable of control to perform a hot gas heating operation in which the refrigerant compressed by the compressor dissipates heat in the indoor heat exchanger without causing the refrigerant to absorb heat in the external heat exchanger, and heats the vehicle cabin. The vehicle air conditioning system is configured to switch to a restriction mode in which an upper limit of the air volume blown by the blower is lowered if the control device determines during the hot gas heating operation that the temperature of the air after heat exchange in the indoor heat exchanger is below a predetermined temperature. Effect of the Invention

[0008] According to the present invention, it is possible to realize a hot gas heating operation in which the thermodynamic cycle does not become unstable even when an external disturbance occurs. [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 of the present invention; [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 is a diagram showing a transition to a regulated mode of the blower operation according to the 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 in the refrigerant circuit 10 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 air conditioning unit 20, the control targets are the blower 23, the air dampers 24, 25, etc., and in the heat medium circuit 30, the control targets are the circulation pump 31, etc. The control device 100 can switch between an endothermic heating operation in which the refrigerant absorbs heat in the external heat exchanger 11, and a hot gas heating operation in which the refrigerant compressed by the compressor 2 dissipates heat in the indoor heat exchanger 21 without absorbing heat in 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 the surrounding environment 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] [Excessive heat release during hot gas heating operation] If a disturbance occurs during hot gas heating operation and the indoor heat exchanger 21 releases heat to low-temperature air, the thermodynamic cycle will be reduced. An example of a disturbance will be explained with reference to Fig. 4. In Fig. 4, when the air damper 25 is in the intermediate position and air inlet 25A and air inlet 25B are half-opened, the system is in half-outdoor air circulation heating mode. Also, the air damper 24 has moved from the position shown in Fig. 4 and is open, so that part of the air that has passed through the blower 23 passes through the indoor heat exchanger 21, while the rest does not.

[0038] In this state, when the vehicle leaves a tunnel and travels in extremely low temperature outdoor air during the hot gas heating operation with semi-outdoor air circulation, the outdoor temperature taken in through the air inlet 25A drops. The temperature of the air exchanging heat in the indoor heat exchanger 21 drops. This increases the heat dissipation of the refrigerant in the indoor heat exchanger 21, which may result in excessive heat dissipation. When the vehicle enters a tunnel, the air flow rate increases, which may result in excessive heat dissipation. In addition, if the window or door is opened in the low temperature outdoor air or the vehicle speed is increased to increase the heat dissipation from the cabin, the indoor temperature drops, which may result in a drop in the temperature of the air exchanging heat in the indoor heat exchanger 21, which may result in excessive heat dissipation.

[0039] Also, when air damper 25 moves from the above state to fully open air inlet 25A and the amount of outside air taken in increases, the temperature of the air exchanging heat in indoor heat exchanger 21 drops. Also, when air damper 24 moves from the above state to the closed position shown in Fig. 4 and the amount of air passing through indoor heat exchanger 21 increases, heat dissipation from indoor heat exchanger 21 increases, which may result in excessive heat dissipation.

[0040] FIG. 6 shows the thermodynamic cycle in the case where the above-mentioned disturbance occurs and excessive heat is released. After the compression process from a1 to b1, if excessive heat is released in the condensation process of the indoor heat exchanger 21, the cycle shifts from b1 to c1. The specific enthalpy h at point c1 becomes smaller than the specific enthalpy h at point c in FIG. 5. Then, when the refrigerant is depressurized in the third depressurization section V3, the refrigerant reaches point d1. Also, the refrigerant in the hot gas bypass 10V is depressurized in the second depressurization section V2 and reaches point dh1. Then, the refrigerants merge at the junction point P2, heat exchange occurs between the refrigerants, and the refrigerant reaches point a2. At point a2, the specific enthalpy h is smaller than that 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 continues after the compression process from a2 to b2, the specific enthalpy h becomes smaller and the thermodynamic cycle shrinks.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Therefore, in the embodiment of the present invention, when excessive heat dissipation occurs, a restriction mode is set to lower the upper limit of the airflow Af of the blower 23. In the restriction mode, the airflow Af is limited to the lowered upper limit or less. Even if an attempt is made to increase the airflow Af, it can only be increased up to the upper limit.

[0045] In the vehicle air conditioner 1, the blowing air temperature sensor 461 measures the temperature of the blowing side of the indoor heat exchanger 21. This monitors the temperature of the air after heat exchange by the indoor heat exchanger 21. As shown in Fig. 4, during hot gas heating operation, heat is dissipated by the indoor heat exchanger 21. Then, the air whose temperature has increased due to heat dissipation is measured by the blowing air temperature sensor 461 to obtain the blowing air temperature Thp.

[0046] When the control device 100 judges that the blown air temperature Thp, which is the temperature of the air after heat exchange in the indoor heat exchanger 21, is equal to or lower than the predetermined temperature Tp during hot gas heating operation, the control device 100 sets the control mode to lower the upper limit of the air volume Af of the blower 23 shown in FIG. 4. By setting the control mode, the amount of heat released by the indoor heat exchanger 21 is suppressed, and the relationship between the acquired energy Qin obtained by the refrigerant and the released energy Qout can be set to a state of acquired energy Qin≧Qout. Then, the reduction of the thermodynamic cycle can be suppressed to make the safety device less likely to operate, and the hot gas heating operation mode can be made less likely to stop. This reduces the number of stops and restarts, and suppresses the discomfort of the occupants. Also, in the restriction mode in the embodiment, the blown air temperature is less likely to drop. Therefore, it is possible to suppress a decrease in the feeling of warmth.

[0047] In this embodiment, whether or not excessive heat dissipation is occurring is roughly determined based on the temperature of the blown air temperature sensor 461. The released energy Qout is obtained by the product of the blown air temperature Thp, which is the temperature of the air after heat exchange in the indoor heat exchanger 21, and the air volume Af of the blower 23. Therefore, for more accurate control, the temperature at which excessive heat dissipation occurs depending on the air volume of the blower 23 may be calculated and set as the predetermined temperature Tp.

[0048] [Transition to regulated mode during hot gas heating operation] An example of transition to the regulated 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 F / B mode" is not a regulated mode. The "Blower Low mode" is a mode in which the upper limit of the air volume Af by the blower 23 is lowered. Furthermore, the "Blower OFF mode" stops the blower 23 and adjusts the air volume Af to 0 m 3 / min. The "blower low mode" and "blower off mode" are restriction modes that lower the upper limit of the airflow Af of the blower 23. The "blower low mode" is a mode in which the upper limit is lowered and the airflow Af can be increased or decreased by adjustment.

[0049] 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, when the blown air temperature Thp falls below the first threshold value T1 during hot gas heating operation in the "blower F / B mode", the mode transitions to the "blower low mode" as indicated by "1". As a result, the upper limit of the air volume Af of the blower 23 is lowered in the restriction mode to be restricted to a predetermined value or less. Note that the "blower F / B mode" also has an upper limit of the air volume Af due to the performance limits of the blower 23, etc.

[0050] In the "Blower Low Mode", if the blown air temperature Thp remains below the first threshold T1 for a period of time equal to or longer than a predetermined period of time, the mode transitions to the "Blower OFF Mode" as shown by "2" in Fig. 7. This stops the blower 23 and reduces the air volume Af to 0 m 3 / min. The "Blower OFF mode" is also a regulated mode. If the blown air temperature Thp does not exceed the first threshold value T1 even after a predetermined time has elapsed after switching from the "Blower F / B mode" to the "Blower Low mode" and lowering the upper limit of the air volume Af, this indicates a situation in which the specific enthalpy h of the refrigerant in hot gas heating operation has not been restored. In such a case, the blower 23 is stopped to restore the specific enthalpy h of the refrigerant. When switching from the "Blower OFF mode" to the "Blower Low mode" by "3" described later, if the state in which the blown air temperature Thp does not exceed the first threshold value T1 continues for a predetermined time, the "Blower OFF mode" is also returned to by "2".

[0051] In addition, in the "Blower F / B mode", when the blown air temperature Thp is equal to or lower than the second threshold T2 that is lower than the first threshold T1, the mode also transitions to the "Blower OFF mode" as shown by "5" in Fig. 7. When the blown air temperature Thp is equal to or lower than the second threshold T2, the specific enthalpy h of the refrigerant is unlikely to recover even if the mode transitions to the "Blower Low mode" and the air volume Af is reduced. Therefore, the mode is set to the "Blower OFF mode" as described above, and the blower 23 is stopped.

[0052] In the "Blower OFF mode", when the blown air temperature Thp reaches the first threshold value T1+α, the mode transitions to the "Blower Low mode" according to "3" in Fig. 7. "+α" is a temperature difference set to suppress oscillation between the "Blower Low mode" and the "Blower OFF mode".

[0053] In the "Blower Low Mode", when the blown air temperature Thp reaches the first threshold value T1+β, the mode transitions to the "Blower F / B Mode" according to "4" in Fig. 7. Note that α and β are positive numbers, and the magnitude relationship between them is α<β.

[0054] The above-mentioned "blower low mode" lowers the upper limit of the air volume Af of the blower 23 to regulate it to a predetermined value or less, and the air volume Af may increase or decrease below the predetermined value. However, the "blower low mode" may be a mode in which the air volume Af of the blower 23 is regulated to a lower limit value, which is the lowest stage of the multiple stages of the air volume Af, to set the air volume Af to the weakest constant value.

[0055] 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.

[0056] In the "blower low mode" of the restriction mode in the embodiment, the upper limit of the air volume Af by the blower 23 is lowered, and the air volume Af can be increased or decreased below the upper limit. However, the air volume Af may be fixed at a low value.

[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, Qin: Energy gained, Qout: Energy released, Thp: outlet air temperature, Tp: specified temperature, T1: first threshold, T2: second 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 the hot gas heating operation is being performed and the temperature of the air after heat exchange in the indoor heat exchanger is determined to be equal to or lower than a predetermined temperature, the vehicle air conditioner enters a regulated mode in which an upper limit value of the air volume blown by the blower is lowered.

2. The control device includes:

2. The vehicle air conditioner according to claim 1, wherein when a temperature of the air after heat exchange in the interior heat exchanger is equal to or lower than a first threshold value, the restriction mode is set to restrict an air volume from the blower to a lower limit value.

3. The control device includes:

3. The vehicle air conditioning system according to claim 2, wherein the blower is stopped in the regulated mode when the temperature of the air after heat exchange with the indoor heat exchanger becomes equal to or lower than a second threshold value that is lower than the first threshold value, or when the period during which the temperature of the air is equal to or lower than the first threshold value continues for a predetermined period of time or longer.

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