Vehicular air conditioning device

Abstract

[Problem] To achieve rapid warm-up by reducing the time it takes for the pressure of a refrigerant on the high-pressure side of a refrigerant circuit to reach a target pressure. [Solution] This vehicular air conditioner includes: a refrigerant circuit including a compressor, an indoor heat exchange unit, an outdoor heat exchange unit, and a hot gas bypass through which at least a portion of a refrigerant compressed by the compressor is decompressed and returns to the compressor by bypassing the indoor heat exchange unit and the outdoor heat exchange unit; an air conditioning unit in which the indoor heat exchange unit is disposed, and which has therein a blower for blowing air and an air damper for adjusting what proportion of air blown by the blower is blown to the indoor heat exchange unit; and a control device for controlling the refrigerant circuit and the air conditioning unit. The control device initiates a hot gas heating mode in which a portion of the refrigerant compressed by the compressor is made to flow to the indoor heat exchange unit and the rest is made to flow to the hot gas bypass, and controls the air damper so that at least a portion of the air bypasses the indoor heat exchange unit when the blower is started.

Description

Vehicle air conditioning system

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

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

[0003] In vehicle air conditioners that use a heat pump, an external heat exchanger functions as a heat absorber during heating operation to obtain heat from outside air. Therefore, when the outside temperature becomes extremely low, it becomes difficult to absorb heat from the outside air, resulting in a significant decrease in heating capacity. In contrast, hot gas heating, which does not absorb heat from outside air or the like, but instead uses high-temperature, high-pressure refrigerant discharged from a compressor, is known as an effective heating method in extremely low-temperature environments.

[0004] For example, in the vehicle air conditioning system of Patent Document 1, a heat pump circulates refrigerant to perform hot gas heating operation as follows: In the heat pump, a portion of the high-temperature, high-pressure refrigerant discharged from the compressor flows through a bypass flow path to be decompressed and then returned to the compressor, while the remainder exchanges heat with air blown into the vehicle cabin in an indoor heat exchanger, is decompressed, and then returned to the compressor without passing through an external heat exchanger.

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

[0006] In the vehicle air conditioning system described above, when hot gas heating operation is started, in order to ensure rapid heating, the blower is stopped to limit heat dissipation in the indoor heat exchanger, while the compressor is driven at a high target rotation speed, and the indoor heat exchanger outlet refrigerant pressure Pci is controlled to reach the target outlet refrigerant pressure Pco as quickly as possible.

[0007] On the other hand, if the compressor continues to operate under such conditions, the outlet refrigerant pressure Pci may rise sharply and overshoot, which may cause the compressor to stop due to high-pressure protection. On the other hand, if the target rotation speed of the compressor is reduced, it will take time for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco.

[0008] Therefore, in a vehicle air conditioner, the blower is driven when the outlet refrigerant pressure Pci has risen to a certain level, and the refrigerant heat is dissipated into the air blown to the indoor heat exchanger, thereby preventing a sudden and excessive increase in the outlet refrigerant pressure Pci. At this time, the blower is driven at the minimum rotation speed (minimum voltage) so as to provide a minimum airflow rate at least at the start of operation, so as to prevent excessive heat dissipation from the indoor heat exchanger.

[0009] However, the minimum rotational speed of the blower is determined by specifications, and it is not possible to operate the blower at a lower airflow rate than the minimum airflow rate achieved by operating the blower at the minimum rotational speed. As a result, the minimum airflow rate determined by specifications is blown to the indoor heat exchanger, which may temporarily cause a large drop in the outlet refrigerant pressure Pci. In this case, it takes time to reach the target outlet refrigerant pressure Pco, which is contrary to the objective of ensuring fast heating.

[0010] The present invention was made in consideration of these circumstances, and its objective is to shorten the time it takes for the high-pressure side refrigerant pressure of the refrigerant circuit to reach the target pressure during hot gas heating operation, thereby shortening the time it takes to reach the target blowing temperature and target heating capacity, i.e., ensuring fast heating.

[0011] The present invention provides a vehicle air conditioning system comprising: a refrigerant circuit including a compressor, an indoor heat exchanger, an external heat exchanger, and a hot gas bypass that decompresses and returns at least a portion of the refrigerant compressed by the compressor without passing through the indoor heat exchanger and the external heat exchanger; an air conditioning unit having the indoor heat exchanger disposed therein and having a blower that blows air into the unit and an air damper that adjusts the proportion of the air blown by the blower that is blown to the indoor heat exchanger; and a control device that controls the refrigerant circuit and the air conditioning unit.The control device is capable of executing a hot gas heating mode in which a portion of the refrigerant compressed by the compressor flows to the indoor heat exchanger and the remainder flows to the hot gas bypass, and when execution of the hot gas heating mode is started and the blower is started, the control device controls the air damper so that at least a portion of the air bypasses the indoor heat exchanger.

[0012] According to the present invention, during hot gas heating operation, the time required for the high-pressure side refrigerant pressure of the refrigerant circuit to reach the target pressure can be shortened, thereby shortening the time required to reach the target blowing temperature and target heating capacity, i.e., ensuring fast heating.

[0013] 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; 2 is an explanatory diagram showing a control device of a vehicle air conditioner according to an embodiment of the present invention; 3 is a diagram showing the configuration of a control device, etc., in an electric vehicle (EV) according to an embodiment of the present invention; 4 is an explanatory diagram showing the operation of a refrigerant circuit during hot gas heating operation in a vehicle air conditioner according to an embodiment of the present invention; and 5 is a graph showing an example of the behavior of the outlet refrigerant pressure of an indoor heat exchanger and the amount of air passing through the indoor heat exchanger during hot gas heating operation in a vehicle air conditioner according to an embodiment of the present invention and a vehicle air conditioner according to a reference example.

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

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

[0016] The vehicle air conditioner 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21 and 22 provided inside the air conditioning unit 20, and an external heat exchanger 11 provided outside the vehicle cabin, which are arranged along a refrigerant flow path. The indoor heat exchangers 21 and 22 are provided to exchange heat between the refrigerant and air flowing through the air conditioning unit 20, and the external heat exchanger 11 is provided to exchange heat between the refrigerant and outside air outside the vehicle cabin. The indoor heat exchanger 21 is used to heat the air, and the indoor heat exchanger 22 is used to cool the air. A refrigerant pressure sensor 44B is provided immediately downstream of the indoor heat exchanger 21 to detect an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) from the indoor heat exchanger 21.

[0017] The compressor 2 compresses the refrigerant and circulates it through the refrigerant circuit 10. The refrigerant compressed by the compressor 2 is reduced to a required pressure by passing through an appropriately selected refrigerant flow path, for example, 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 expansion valves. The refrigerant circuit 10 is provided with flow path switching valves 12 and 13 for switching the refrigerant flow path and check valves 14 and 15 for regulating the flow direction of the refrigerant. 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. A refrigerant pressure sensor 44A is provided between the accumulator 16 and the compressor 2 to detect a suction refrigerant pressure Ps (low-pressure side refrigerant pressure) drawn into the compressor 2.

[0018] As described above, the air conditioning unit 20 is equipped with the indoor heat exchangers 21, 22 inside, and air introduced from the room or the outside by the blower 23 passes through the indoor heat exchangers 21, 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, 22 and is blown into the room.

[0019] Furthermore, when the air damper 24 is fully closed, it blocks the inlet side of the indoor heat exchanger 21, and air introduced by the blower 23 passes only through the indoor heat exchanger 22 before being blown into the room. Another air damper 25 provided in the air conditioning unit 20 switches the air introduced into the blower 23 between indoor and outdoor. The air damper 25 can selectively close an air inlet 25A connected to the outdoors or an air inlet 25B connected to the indoors, allowing air to be introduced from either one. Furthermore, by setting the air damper 25 to an intermediate position, air can be introduced from both the air inlet 25A and the air inlet 25B.

[0020] Although the above-described external heat exchanger 11 and indoor heat exchangers 21, 22 have been described as examples in which the refrigerant directly exchanges heat with the air, the refrigerant may indirectly exchange heat with the air via a heat medium that has exchanged heat with the refrigerant. That is, the refrigerant may absorb heat from the air via the heat medium, or the refrigerant may release heat to the air via the heat medium.

[0021] As shown in Fig. 1, the vehicle air conditioner 1 includes a heat medium circuit 30. The heat medium circuit 30 circulates a heat medium using a circulation pump 31, heats the heat medium using a heater (ECH: Electric Coolant Heater) 32, and recovers waste heat from a temperature-controlled object such as a battery using a temperature-controlled object heat exchanger 33. The refrigerant circuit 10 and the heat medium circuit 30 are provided with a refrigerant-heat medium heat exchanger 34 that exchanges heat between the refrigerant and the heat medium via a flow path 34A through which the refrigerant flows and a flow path 34B through which the heat medium flows. The heat medium circuit 30 is provided as needed.

[0022] The vehicle air conditioner 1 includes a control device 100 shown in Fig. 2. The control device 100 controls the refrigerant circuit 10, the air conditioning unit 20, and the heat medium circuit 30 based on various input signals (such as an air conditioning instruction signal and a charger connection signal) and detection signals from the sensor unit 40.

[0023] The sensor unit 40 that inputs detection signals to the control device 100 includes, for example, an outside air sensor 41 that detects outside air conditions such as 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 an air temperature sensor 46 that detects the air temperature of the air conditioning unit 20.

[0024] In particular, the refrigerant pressure sensor 44 includes a refrigerant pressure sensor 44A that detects a suction refrigerant pressure Ps (low-pressure side refrigerant pressure) sucked into the compressor 2, and a refrigerant pressure sensor 44B that detects an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) of the indoor heat exchanger 21 (see FIG. 1). These sensors are just examples, and the sensor unit 40 is provided with various sensors that detect information required for the control device 100 to perform various controls.

[0025] The control devices of the control device 100 are the compressor 2, the first pressure reduction section V1, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valves 12 and 13 in the refrigerant circuit 10, the blower 23, the air dampers 24 and 25 in the air conditioning unit 20, and the circulation pump 31 in the heat medium circuit 30. The control device 100 also controls the vehicle air conditioner 1 according to the processing results of the control device 100. The vehicle air conditioner 1 can be switched by the control device 100 between an endothermic heating operation in which the refrigerant is caused to absorb heat in the external heat exchanger 11, and a hot gas heating operation in which the refrigerant compressed by the compressor 2 is caused to release heat in the indoor heat exchanger 21 without absorbing heat in the external heat exchanger 11, thereby heating the vehicle cabin.

[0026] [Configuration of Control Device in Electric Vehicle (EV)] As shown in Fig. 3 , the control device 100 provided in the vehicle air conditioner 1 is configured as a single ECU connected to various ECUs (Electronic Control Units) that control the electric vehicle EV via an in-vehicle network L. The control device 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an I / F (Interface) 104 for input / output, an I / F (Interface) 105 for in-vehicle communication, and the like, and each piece of hardware is connected to one another via a bus 106.

[0027] The CPU 101 controls the control device 100 by executing various programs stored in the ROM 102. The ROM 102 is a non-volatile memory. For example, the ROM 102 stores programs executed by the CPU 101, data necessary for the CPU 101 to execute the programs, etc. The RAM 103 is a main storage device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM).

[0028] For example, RAM 103 functions as a work area used by CPU 101 when executing a program. Input / output I / F 104 is connected to various sensors and monitors installed in the EV, and inputs data to CPU 101 and outputs data processed by CPU 101. In-vehicle communication I / F 105 is connected to an in-vehicle network L, and controls data transmission and reception with other ECUs set in the EV.

[0029] The control device 100 controls the above-mentioned vehicle air conditioning device 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.

[0030] 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.

[0031] [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 not allowed to absorb heat in the external heat exchanger 11, but some or all of the refrigerant is dissipated in the indoor heat exchanger 21 to heat the vehicle interior.

[0032] The operation of the refrigerant circuit 10 during hot gas heating operation will be described with reference to Figure 4. In this operation, a portion of the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 and the flow switching valve 12, is decompressed in the third pressure reduction section V3 to become a low-pressure refrigerant, passes through the refrigerant heat medium heat exchanger 34, undergoes gas-liquid separation in the accumulator 16, and returns to the compressor 2. At this time, in the refrigerant circuit 10, the first pressure reduction section V1 is fully closed, so that refrigerant does not flow to the external heat exchanger 11. In addition, the fourth pressure reduction section V4 is fully closed, so that refrigerant does not flow to the indoor heat exchanger 22.

[0033] 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.

[0034] By providing such a hot gas bypass 10V, the liquid refrigerant condensed by heat radiation in the indoor heat exchanger 21 is mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant that can be returned to the compressor 2. Furthermore, by increasing the flow rate of refrigerant flowing through the hot gas bypass 10V, the amount of heat radiation in the indoor heat exchanger 21 can be suppressed, and by adjusting the flow rate of refrigerant flowing through the hot gas bypass 10V by opening or closing the second pressure reduction section V2, it is possible to maintain a balance between the amount of heat radiation from the refrigerant circuit 10 and the amount of heat input to the compressor 2. In other words, the second pressure reduction section V2 functions as a flow rate adjustment section that adjusts the flow rate of refrigerant flowing through the hot gas bypass 10V.

[0035] During hot gas heating operation, the refrigerant flow in the flow path passing through the indoor heat exchanger 21 is decompressed in the third decompression section V3, so that the refrigerant becomes high-pressure refrigerant upstream and low-pressure refrigerant downstream. In this case, it is important to maintain heating capacity that heat exchange does not occur in the refrigerant / heat medium heat exchanger 34 in the low-pressure flow path. In the air conditioning unit 20, air introduced by the blower 23 is heated by heat released from the indoor heat exchanger 21 and then blown into the vehicle cabin.

[0036] Although the flow of refrigerant in the refrigerant circuit 10 during endothermic heating operation is not shown, in the refrigerant circuit 10 during 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, while the flow path switching valve 13 is fully open and the first pressure reduction section V1 is open.

[0037] 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, and the low-pressure refrigerant passes through the external heat exchanger 11 and passes through the flow path switching valve 13, the check valve 14, and the accumulator 16 before being returned to the compressor 2. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the indoor heat exchanger 21, is depressurized in the first depressurization section V1 to become low-pressure refrigerant, absorbs heat and evaporates in the external heat exchanger 11, and returns to the compressor 2. In the air conditioning unit 20, air introduced by the blower 23 is heated by the heat released in the indoor heat exchanger 21 and is blown into the vehicle cabin.

[0038] [Adjustment of high-pressure side refrigerant in the refrigerant circuit during hot gas heating operation] When hot gas heating operation is performed in the vehicle air conditioning system 1, the control device 100 performs the following control when the hot gas heating operation begins (including when hot gas heating operation is started and when switching from endothermic heating operation to hot gas heating operation).

[0039] That is, immediately after starting the hot gas heating operation, the control device 100 drives the compressor 2 at a predetermined high rotation speed (for example, the maximum rotation speed) while stopping the drive of the blower 23 to limit heat radiation in the indoor heat exchanger 21 so that the high-pressure side refrigerant pressure of the refrigerant circuit 10 (in this embodiment, this is the outlet refrigerant pressure Pci of the indoor heat exchanger 21) reaches a target pressure (target outlet refrigerant pressure Pco). Thereafter, when the outlet refrigerant pressure Pci rises to a predetermined pressure, the control device 100 starts the drive of the blower 23 and controls the air damper 24 to suppress an excessive rise in the outlet refrigerant pressure Pci.

[0040] The behavior of the outlet refrigerant pressure Pci when the control device 100 performs the above-described control will be described below in comparison with a reference example. Fig. 5 is a graph showing an example of the relationship between the behavior of the outlet refrigerant pressure Pci when the control device 100 performs the above-described control and the amount of air passing through the indoor heat exchanger 21 in the vehicle air conditioner 1 according to this embodiment and the reference example. Note that although the example in Fig. 5 does not show the behavior of the compressor 2, in both this embodiment and the reference example, the compressor 2 is driven with its target rotation speed set to its maximum value.

[0041] (Control method according to the reference example) In Figure 5, the behavior of the outlet refrigerant pressure Pci at the start of hot gas heating operation using the control method according to the reference example is Pci_ref, and the amount of air passing through the indoor heat exchanger 21 is AF_ref, both of which are shown by dashed lines.

[0042] When the hot gas heating operation is started, the control device 100 drives the compressor 2 with the target rotation speed set to the maximum value. At this time, the drive of the blower 23 is stopped and no air is sent to the indoor heat exchanger 21, thereby limiting the heat dissipation in the indoor heat exchanger 21. By continuing to drive the compressor 2 in this state, the outlet refrigerant pressure Pci_ref increases, as shown in FIG. 5 .

[0043] During this time, the control device 100 periodically acquires the outlet refrigerant pressure Pci_ref detected by the refrigerant pressure sensor 44B, and when it detects that the acquired outlet refrigerant pressure Pci_ref has reached a predetermined pressure Pci_th that is lower than the target outlet refrigerant pressure PCO, it drives the blower 23 to start sending air to the indoor heat exchanger 21. At this time, the control device 100 drives the blower 23 at the minimum rotation speed and controls the air damper 24 to be fully open. Therefore, a minimum amount of air is introduced into the air conditioning unit 20 according to the minimum rotation speed of the blower 23, and after passing through the indoor heat exchanger 22, the introduced air is blown by the air damper 24 so that all of the air passes through the indoor heat exchanger 21 (AF_ref in FIG. 5 ).

[0044] Therefore, in the indoor heat exchanger 21, heat is dissipated from the refrigerant to all of the air introduced into the air conditioning unit 20 by the blower 23, and accordingly, the outlet refrigerant pressure Pci_ref temporarily drops. That is, after time T1 when the blower 23 starts to be driven, the outlet refrigerant pressure Pci_ref temporarily drops.

[0045] Thereafter, the outlet refrigerant pressure Pci increases again by continuing to drive the compressor 2 at the maximum rotation speed, but the time required for the outlet refrigerant pressure Pci_ref to reach the target outlet refrigerant pressure PCO increases by the amount that the outlet refrigerant pressure Pci_ref decreased when the blower 23 was started. As a result, the time required for the blowing temperature to reach the target blowing temperature and the time required for the heating capacity to reach the target heating capacity also increase, making it impossible to ensure quick heating, and reducing user comfort.

[0046] (Control Method According to the Present Embodiment) Therefore, in the present embodiment, when the hot gas heating mode is started and the blower 23 is activated, the control device 100 controls the air damper 24 so that at least a portion of the air bypasses the indoor heat exchanger 21. That is, when the blower 23 is driven, the opening degree of the air damper 24 is controlled to adjust the proportion of the air introduced into the air conditioning unit 20 by the blower 23 that is sent to the indoor heat exchanger 21, thereby suppressing an excessive increase in the outlet refrigerant pressure Pci. This will be described in detail below.

[0047] When the hot gas heating operation is started, the control device 100 drives the compressor 2 with the target rotation speed set to the maximum value. At this time, the drive of the blower 23 is stopped and no air is sent to the indoor heat exchanger 21, thereby limiting the heat dissipation in the indoor heat exchanger 21. By continuing to drive the compressor 2 in this state, the outlet refrigerant pressure Pci increases, as shown in Figure 5.

[0048] During this time, the control device 100 acquires the outlet refrigerant pressure Pci detected by the refrigerant pressure sensor 44B at a predetermined cycle, and when it detects that the acquired outlet refrigerant pressure Pci has reached a predetermined pressure Pci_th that is lower than the target outlet refrigerant pressure PCO, it drives the blower 23 to start sending air to the indoor heat exchanger 21. At this time, the control device 100 drives the blower 23 at the minimum rotation speed and controls the opening degree of the air damper 24. By driving the blower 23 at the minimum rotation speed when started, the amount of air sent to the indoor heat exchanger 21 can be minimized, thereby minimizing the amount of heat radiation in the indoor heat exchanger 21.

[0049] 5, the control device 100 adjusts the opening of the air damper 24 to a position approximately halfway between fully open and fully closed, and controls the air so that approximately half of the air blown by the blower 23 is blown to the indoor heat exchanger 21. Therefore, a minimum amount of air is introduced into the air conditioning unit 20 according to the minimum rotation speed of the blower 23, and after the introduced air passes through the indoor heat exchanger 22, the air damper 24 blows approximately half of the air so that it passes through the indoor heat exchanger 21 (AF in FIG. 5).

[0050] Therefore, in the indoor heat exchanger 21, heat is dissipated from the refrigerant to approximately half of the air of the minimum volume introduced into the air conditioning unit 20 by the blower 23. At the same time, the outlet refrigerant pressure Pci rises because the compressor 2 continues to operate at the maximum rotation speed, but after time T1 when the blower 23 starts operating, the outlet refrigerant pressure Pci rises somewhat more slowly than before time T1. The outlet refrigerant pressure Pci rises somewhat more slowly than before time T1, and reaches the target outlet refrigerant pressure Pco at time T2.

[0051] Although the outlet refrigerant pressure Pci becomes slightly higher than the target outlet refrigerant pressure Pco after time T2, this pressure is within an allowable range for the target outlet refrigerant pressure Pco. In this way, in this embodiment, the outlet refrigerant pressure Pci reaches the target outlet refrigerant pressure Pco at time T2, and it can be said that the time required for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco is shortened.

[0052] 5, an example has been described in which the opening degree of the air damper 24 is adjusted to somewhere between fully open and fully closed when the blower 23 is started, but the opening degree of the air damper 24 when the blower 23 is started and the subsequent adjustment of the opening degree can be adjusted as appropriate. For example, when the blower 23 is started, the air damper 24 is fully closed to block the suction side of the indoor heat exchanger 21 and cut off the air flow path to the indoor heat exchanger 21, and then the air damper 24 can be driven linearly or stepwise in the opening direction according to the outlet refrigerant pressure Pci to adjust the amount of air sent to the indoor heat exchanger 21.

[0053] By doing this, when the blower 23 is started, all of the air blown from the blower 23 is prevented from being suddenly introduced into the indoor heat exchanger 21, thereby suppressing a sudden increase in the amount of heat dissipated in the indoor heat exchanger 21 and reducing the decrease in the outlet refrigerant pressure Pci immediately after the blower 23 is started.

[0054] Furthermore, when the air damper 24 is driven from the fully closed position toward the open position linearly or stepwise in response to the outlet refrigerant pressure Pci, the air damper 24 is controlled so that the decrease (amount of decrease) of the outlet refrigerant pressure Pci falls within a predetermined range. The predetermined range can be determined in advance as a range that ensures fast warm-up, that is, as a range that is allowable in response to a target time for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco. This allows the decrease of the outlet refrigerant pressure Pci to fall within an allowable range, thereby shortening the time required for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco and shortening the time required for the blown air temperature to reach the target blown air temperature.

[0055] In this manner, in this embodiment, when the hot gas heating operation starts, the amount of heat dissipated in the indoor heat exchanger 21 is adjusted by controlling the opening of the air damper 24 in addition to driving the blower 23. This suppresses a sudden and excessive increase in the outlet refrigerant pressure Pci, preventing an overshoot beyond the allowable range and ultimately preventing the compressor 2 from being stopped due to high-pressure protection, and also shortens the time required for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco.

[0056] Furthermore, by shortening the time it takes for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco, it is possible to shorten both the time it takes for the blow-out temperature to reach the target blow-out temperature and the time it takes for the heating capacity to reach the target heating capacity, thereby ensuring quick heating and improving user comfort.

[0057] In particular, by operating the blower 23 at the minimum rotation speed when started and by minimizing the air volume sent to the indoor heat exchanger 21 by the air damper 24, the amount of heat radiation from the indoor heat exchanger 21 can be minimized, thereby minimizing the decrease in the outlet refrigerant pressure Pci. This reduces the time it takes for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco, the time it takes for the blown air temperature to reach the target blown air temperature, and the time it takes for the heating capacity to reach the target heating capacity, thereby minimizing the impact on user comfort.

[0058] As described above, in this embodiment, an example has been described in which the outlet refrigerant pressure Pci and the target outlet refrigerant pressure PCO of the indoor heat exchanger 21 are used as the high-pressure side refrigerant pressure and its target pressure, but it is also possible to use, for example, the discharge pressure and the target discharge pressure of the compressor 2 as the high-pressure side refrigerant pressure.

[0059] As described above, according to this embodiment, during hot gas heating operation, the time required for the high-pressure side refrigerant pressure of the refrigerant circuit to reach the target pressure can be shortened, thereby shortening the time required to reach the target blowing temperature and target heating capacity, i.e., fast heating can be ensured.

[0060] The embodiments of the present invention have been described above in detail with reference to the drawings, but the specific configurations are not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.

[0061] 1: Vehicle air conditioning device, 2: Compressor, 10: Refrigerant circuit, 10V: Hot gas bypass, 11: External heat exchanger, 12, 13: Flow path switching valve, 14, 15: Check valve, 16: Accumulator, 20: Air conditioning unit, 21, 22: Indoor heat exchanger, 23: Blower, 24, 25: Air damper, 25A, 25B: Air inlet, 30: Heat medium circuit, 31: Circulation pump, 33: Temperature-controlled heat exchanger, 34: Refrigerant heat medium heat exchanger, 34A, 34B: Flow path, 40: Sensor unit, 41: Outside air sensor, 42: Compressor current sensor, 43: Refrigerant temperature sensor, 44, 44A, 44B: Refrigerant pressure sensor, 45: Occupant sensor, 46: Air supply temperature sensor, 100: Control device

Claims

1. 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 and returns it to the compressor without passing through the indoor heat exchange unit and the external heat exchange unit; an air conditioning unit having the indoor heat exchange unit disposed therein and having a blower that blows air into the interior and an air damper that adjusts the proportion of the air blown by the blower that is blown to the indoor heat exchange unit; and a control device that controls the refrigerant circuit and the air conditioning unit, wherein the control device is capable of executing a hot gas heating mode in which a portion of the refrigerant compressed by the compressor flows through the indoor heat exchange unit and the remainder flows through the hot gas bypass, and when execution of the hot gas heating mode begins and the blower is started, the control device controls the air damper so that at least a portion of the air bypasses the indoor heat exchange unit.

2. The vehicle air conditioner according to claim 1, wherein the control device starts the blower at a minimum rotation speed.

3. A vehicle air conditioning system as described in claim 1 or claim 2, wherein the refrigerant circuit includes a pressure sensor that detects the pressure of the refrigerant that has flowed through the indoor heat exchange section, and the control device controls the air damper when the blower is started so that the amount of reduction in pressure detected by the pressure sensor is within a predetermined range.

4. The vehicle air conditioner according to claim 1 or 2, wherein the control device controls the air damper to a position where it blocks the air passage to the indoor heat exchanger when the blower is started.

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