Vehicular air conditioner

Abstract

To shorten a time required for pressure of high pressure-side refrigerant in a refrigerant circuit to reach target pressure to secure quick heating performance.SOLUTION: A vehicular air conditioner comprises; a refrigerant circuit which includes a compressor, an indoor heat exchange part, an external heat exchange part, and a hot gas bypass through which at least a portion of a refrigerant compressed by the compressor is decompressed and returned to the compressor without going through the indoor heat exchange part and the external heat exchange part; an air conditioning unit, in which the indoor heat exchange part is arranged, and which has an air blower that blows air to the inside and an air damper that adjusts a rate of air to be blown to the indoor heat exchange part of air blown by the blower; and a control device that controls the refrigerant circuit and the air conditioning unit. The control device starts to execute a hot gas heating mode of flowing a portion of the refrigerant compressed by the compressor to the indoor heat exchange part and the residue thereof to the hot gas bypass, and when activating the air blower, controls the air damper so that at least a portion of air bypasses the indoor heat exchange part.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

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

[0004] For example, in the vehicle air conditioner of Patent Document 1, the heat pump circulates the refrigerant to perform hot gas heating operation as follows: In other words, in the heat pump, part 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, and the remainder is heat exchanged with air to be blown into the vehicle cabin in an indoor heat exchanger, after which it is decompressed and returned to the compressor without passing through an external heat exchanger. [Prior art documents] [Patent documents]

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

[0006] 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 is continued to be driven in this state, the outlet refrigerant pressure Pci may rise suddenly and overshoot, causing 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 the vehicle air conditioner, the blower is driven when the outlet refrigerant pressure Pci has risen to a certain level, and the heat of the refrigerant is dissipated to the air blown to the indoor heat exchanger, thereby suppressing 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 driving, so as to prevent the amount of heat dissipated from the indoor heat exchanger from becoming excessive.

[0009] However, the minimum rotation speed of the blower is determined by the specifications, and it is not possible to drive the blower so as to blow less air than the minimum amount of air that can be obtained by driving the blower at the minimum rotation speed. Therefore, the minimum amount of air that is determined by the specifications is blown to the indoor heat exchanger, which may cause the outlet refrigerant pressure Pci to drop significantly temporarily. In this case, it takes time to reach the target outlet refrigerant pressure Pco, which is contrary to the purpose of ensuring fast heating.

[0010] The present invention has been made in consideration of the above circumstances, and has as its objective the shortening of 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 rapid heating. [Means for solving the problem]

[0011] The present invention provides an air conditioning system for a vehicle 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 in which the indoor heat exchange unit is disposed inside and which has 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 into the indoor heat exchange unit and the remainder flows into 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 exchange unit. Effect of the Invention

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

[0013] [Figure 1] 1 is an explanatory diagram showing an example of a system configuration of a vehicle air conditioner according to an embodiment of the present invention; [Diagram 2] 1 is an explanatory diagram showing a control device for a vehicle air conditioner according to an embodiment of the present invention; [Diagram 3] 1 is a diagram showing the configuration of a control device and the like in an electric vehicle (EV) according to an embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram showing the operation of the refrigerant circuit during hot gas heating operation in the vehicle air conditioner according to the embodiment of the present invention. [Diagram 5]11 is a graph showing an example of behavior of the outlet refrigerant pressure of the indoor heat exchanger and the amount of air passing through the indoor heat exchanger during hot gas heating operation in the vehicle air conditioner according to the embodiment of the present invention and the vehicle air conditioner according to the reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[0016] The vehicle air conditioner 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21 and 22 provided inside the air conditioning unit 20, and an external heat exchanger 11 provided outside the vehicle cabin, which are arranged along a refrigerant flow path. The indoor heat exchangers 21 and 22 are provided for heat exchange between the air flowing through the air conditioning unit 20 and the refrigerant, and the external heat exchanger 11 is provided for heat exchange between the outside air and the refrigerant outside the vehicle cabin. The indoor heat exchanger 21 is for heating the air, and the indoor heat exchanger 22 is for cooling the air. A refrigerant pressure sensor 44B 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 in pressure to a required level by passing through a first pressure reducing section V1, a second pressure reducing section V2, a third pressure reducing section V3, and a fourth pressure reducing 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. 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) sucked into the compressor 2.

[0018] As described above, the air conditioning unit 20 includes the indoor heat exchangers 21, 22 therein, 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] When the air damper 24 is fully closed, it blocks the inlet side of the indoor heat exchanger 21, and the 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 air inlet 25A connected to the outdoors and air inlet 25B connected to the indoors to take in air from either one of them. Also, by placing the air damper 25 in an intermediate position, it is possible to take in air from both air inlet 25A and air inlet 25B.

[0020] 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.

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

[0022] [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.

[0023] The sensor section 40, which inputs detection signals to the control device 100, includes, for example, an outside air sensor 41 which detects outside air conditions such as outside air temperature and outside air humidity, a compressor current sensor 42 for detecting the power consumption (energy consumption) of the compressor 2, a refrigerant temperature sensor 43 and a refrigerant pressure sensor 44 which detect the state of the refrigerant, an occupant sensor 45 which detects the presence or absence of an occupant in the vehicle cabin, and a blower temperature sensor 46 which detects the blower 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 merely examples, and various sensors that detect information required when the control device 100 performs various controls are provided as the sensor unit 40.

[0025] The control targets of the control device 100 are the compressor 2, the first pressure reducing section V1, the second pressure reducing section V2, the third pressure reducing section V3, the fourth pressure reducing section V4, and the flow path switching valves 12 and 13 in the refrigerant circuit 10, the blower 23, the air dampers 24 and 25 in the air conditioning unit 20, and the circulation pump 31 in the heat medium circuit 30. The control device 100 also controls the vehicle air conditioner 1 according to the processing results of the control device 100. In the vehicle air conditioner 1, the control device 100 can switch 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 the refrigerant absorbing heat in the external heat exchanger 11, thereby heating the vehicle interior.

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

[0027] The CPU 101 executes various programs stored in the ROM 102 to control the control device 100. The ROM 102 is a non-volatile memory. For example, the ROM 102 stores programs executed by the CPU 101, data necessary for the CPU 101 to execute the programs, etc. The RAM 103 is a main storage device such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory).

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

[0029] The control device 100 controls the above-mentioned vehicle air conditioner 1 by a program executed by the CPU 101 when data related to the surrounding environment or data related to the driving status of the EV is input via the input / output I / F 104 and the in-vehicle I / F 105.

[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 caused to dissipate heat in the indoor heat exchanger 21 to heat the vehicle interior.

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

[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 can be mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant, which can then be returned to the compressor 2. In addition, by increasing the flow rate of the refrigerant flowing through the hot gas bypass 10V, the amount of heat radiation in the indoor heat exchanger 21 can be suppressed, and by opening and closing the second pressure reduction section V2 to adjust the flow rate of the refrigerant flowing through the hot gas bypass 10V, the balance between the amount of heat radiation from the refrigerant circuit 10 and the amount of heat input to the compressor 2 can be maintained. In other words, the second pressure reduction section V2 functions as a flow rate adjustment section that adjusts the flow rate of the refrigerant flowing through the hot gas bypass 10V.

[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 upstream of that becomes high pressure refrigerant and the refrigerant downstream of that becomes low pressure refrigerant. At this time, it is important in order to maintain the heating capacity that heat exchange is not performed in the refrigerant heat medium heat exchanger 34 in the low pressure side flow path. In the air conditioning unit 20, the air introduced by the blower 23 is heated by heat radiation in the indoor heat exchanger 21 and is blown out into the vehicle cabin.

[0036] Although the flow of refrigerant in the refrigerant circuit 10 during endothermic heating operation is not shown in the drawings, 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. On the other hand, 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 is returned to the compressor 2 via the flow path switching valve 13, the check valve 14, and the accumulator 16. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the indoor heat exchanger 21, is depressurized in the first depressurization section V1 to become a low-pressure refrigerant, absorbs heat and evaporates in the external heat exchanger 11, and returns to the compressor 2. In the air conditioning unit 20, the air introduced by the blower 23 is heated by the heat released in the indoor heat exchanger 21 and is blown into the vehicle cabin.

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

[0039] That is, immediately after starting execution of 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, the outlet refrigerant pressure Pci of the indoor heat exchanger 21) becomes the target pressure (target outlet refrigerant pressure Pco). After that, when the outlet refrigerant pressure Pci rises to a predetermined pressure, the control device 100 starts the drive of the blower 23 and suppresses an excessive rise in the outlet refrigerant pressure Pci while controlling the air damper 24.

[0040] The behavior of the outlet refrigerant pressure Pci when the control device 100 performs the above-mentioned control will be described below in comparison with a reference example. Fig. 5 shows a graph showing an example of the relationship between the behavior of the outlet refrigerant pressure Pci when the control described above is performed in the vehicle air conditioner 1 according to this embodiment and the reference example, and the amount of air passing through the indoor heat exchanger 21. 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 a maximum value.

[0041] (Control method according to the reference example) In FIG. 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 denoted by Pci_ref, and the amount of air passing through the indoor heat exchanger 21 is denoted by AF_ref, both of which are indicated 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 acquires the outlet refrigerant pressure Pci_ref detected by the refrigerant pressure sensor 44B at a predetermined cycle, and when it detects that the acquired outlet refrigerant pressure Pci_ref has reached a predetermined pressure Pci_th lower than the target outlet refrigerant pressure PCO, it drives the blower 23 to start blowing air to the indoor heat exchanger 21. At this time, the control device 100 drives the blower 23 at a 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 it 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 rises 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 dropped when the blower 23 was started. This results in a longer time required for the blowing temperature to reach the target blowing temperature and the heating capacity to reach the target heating capacity, making it impossible to ensure rapid heating, and compromising user comfort.

[0046] (Control method according to this embodiment) Therefore, in this embodiment, when the control device 100 starts the hot gas heating mode and starts the blower 23, it controls the air damper 24 so that at least a part 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 by the blower 23 into the air conditioning unit 20 that is blown 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 FIG.

[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 lower than the target outlet refrigerant pressure PCO, it drives the blower 23 to start blowing 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 at the start, the amount of air blown to the indoor heat exchanger 21 can be minimized, and thus the amount of heat dissipated in the indoor heat exchanger 21 can be minimized.

[0049] 5, the control device 100 adjusts the opening degree of the air damper 24 to about halfway between fully open and fully closed, and controls so that about half of the air blown by the blower 23 is blown to the indoor heat exchanger 21. For this reason, 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 about half of that 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 about half of the air of the minimum air 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 manner, 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 has been shortened.

[0052] 5, an example has been described in which the opening degree of the air damper 24 is adjusted to about halfway 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 appropriately performed. 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 block the air blowing 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 blown 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 to the opening direction 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 can ensure fast heating, that is, as an allowable range depending on a target time until the outlet refrigerant pressure Pci reaches the target outlet refrigerant pressure Pco. This allows the decrease in the outlet refrigerant pressure Pci to be within an acceptable range, thereby shortening the time required for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure PCO as well as the time required for the blowing temperature to reach the target blowing temperature.

[0055] In this manner, in this embodiment, at the start of hot gas heating operation, the opening degree of the air damper 24 is controlled in conjunction with the driving of the blower 23 to adjust the amount of heat dissipated in the indoor heat exchanger 21. This suppresses a sudden and excessive rise in the outlet refrigerant pressure Pci, preventing an overshoot that exceeds the allowable range and, ultimately, stopping the driving of the compressor 2 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] In addition, by shortening the time it takes for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure Pco, 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 can both be shortened, ensuring quick heating and improving user comfort.

[0057] In particular, by driving the blower 23 at the minimum rotation speed when started and by setting the air volume sent to the indoor heat exchanger 21 by the air damper 24 to the minimum, the amount of heat dissipated in the indoor heat exchanger 21 is suppressed as much as possible, and the decrease in the outlet refrigerant pressure Pci can be suppressed as much as possible. This makes it possible to shorten the time for the outlet refrigerant pressure Pci to reach the target outlet refrigerant pressure PCO, the time for the blowing temperature to reach the target blowing temperature, and the time for the heating capacity to reach the target heating capacity, and to minimize the impact on the comfort of the user.

[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 it takes for the high-pressure side refrigerant pressure of the refrigerant circuit to reach the target pressure is shortened, thereby shortening the time it takes to reach the target blowing temperature and target heating capacity, i.e., quick heating is ensured.

[0060] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention. [Explanation of symbols]

[0061] 1: vehicle air conditioning system, 2: compressor, 10: refrigerant circuit, 10V: hot gas bypass 11: external heat exchanger, 12, 13: flow path switching valve, 14, 15: check valve 16: accumulator, 20: air conditioning unit, 21, 22: indoor heat exchanger 23: blower, 24, 25: air damper, 25A, 25B: air inlet 30: Heat medium circuit, 31: Circulation pump, 33: Heat exchanger to be temperature-controlled 34: refrigerant / heat medium heat exchanger, 34A, 34B: flow path, 40: sensor unit 41: Outside air sensor, 42: Compressor current sensor, 43: Refrigerant temperature sensor 44, 44A, 44B: refrigerant pressure sensor, 45: occupant sensor, 46: blowing air temperature sensor 100: Control device

Claims

1. a refrigerant circuit including a compressor, an indoor heat exchange unit, an external heat exchange unit, and a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor and returns it to the compressor without passing through the indoor heat exchange unit and the external heat exchange unit; an air conditioning unit having the indoor heat exchanger disposed therein, a blower for blowing air into the interior, and an air damper for adjusting a ratio of the air blown by the blower to be blown to the indoor heat exchanger; a control device for controlling the refrigerant circuit and the air conditioning unit, The control device includes: A hot gas heating mode can be executed in which a part of the refrigerant compressed by the compressor flows into the indoor heat exchange section and the remainder flows into the hot gas bypass. The vehicle air conditioner controls the air damper so that at least a portion of the air bypasses the indoor heat exchanger when execution of the hot gas heating mode is started and the blower is started.

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

3. The refrigerant circuit includes a pressure sensor that detects a pressure of the refrigerant that has flowed through the indoor heat exchanger, 3. The vehicle air conditioner according to claim 1, wherein the control device controls the air damper when the blower is started so that a decrease in pressure detected by the pressure sensor falls within a predetermined range.

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

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