Vehicle air conditioner

Abstract

To improve comfort of an occupant by stably continuing a hot-gas heating mode and suppressing variation in blowout temperature during transition from hot-gas heating to heat-absorption heating.SOLUTION: A vehicle air conditioner comprises a refrigerant circuit, an air conditioning unit, and a controller for controlling the refrigerant circuit and the air conditioning unit. In the vehicle air conditioner, it is possible to execute: a heat-absorption heating mode of causing a refrigerant which has released heat due to heating of a cabin to absorb heat from a heat absorption target such as outside air in an external heat exchanger; and a hot-gas heating mode of returning part of the refrigerant compressed by a compressor to the compressor through a bypass and heating the cabin by heat released by the remaining refrigerant. During transition from the hot-gas heating mode to the heat-absorption heating mode, when a difference between a current heating capacity in the hot-gas heating mode and a heating capacity in the heat-absorption heating mode estimated on the basis of a temperature of the heat absorption target is equal to or greater than a predetermined value, an air damper is driven to lower the current heating capacity in the hot-gas heating mode.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

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

[0004] For example, in the vehicle air conditioning system of Patent Document 1, a hot gas heating mode is executed in which a portion of the high-temperature, high-pressure refrigerant discharged from the compressor is passed through a bypass flow path to be decompressed and then returned to the compressor, while the remainder is heat exchanged with the air blown into the vehicle cabin in an indoor heat exchanger, then decompressed and returned to the compressor without passing through an external heat exchanger. [Prior art documents] [Patent documents]

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

[0006] When heating the passenger compartment in the above-mentioned vehicle air conditioner, for example, the hot gas heating mode is executed at startup to raise the temperature in the passenger compartment as quickly as possible, and then the mode is controlled to transition to the endothermic heating mode after the passenger compartment has reached a desired temperature. In this case, since there is a large difference in heating capacity between the hot gas heating mode and the endothermic heating mode under the same environment, the blown air temperature may fluctuate greatly when transitioning from the hot gas heating mode to the endothermic heating mode, which may impair the comfort of the passengers.

[0007] On the other hand, in order to suppress the fluctuation of the blowing temperature during the transition, it is possible to transition to the endothermic heating mode after lowering the blowing temperature in the hot gas heating mode. When the high-pressure side refrigerant pressure of the refrigerant circuit is lowered, that is, the compressor speed is lowered in order to lower the blowing temperature, the blowing temperature cannot necessarily be lowered to the desired temperature because there is a lower limit to the compressor speed at which a stable operating state can be maintained in the hot gas heating mode. When the compressor is driven at a speed below the above-mentioned lower limit in the hot gas heating mode, the balance between the heat input and heat release in the refrigerant circuit cannot be maintained, the operating state becomes unstable, and there is a risk of the vehicle air conditioner stopping.

[0008] The present invention has been made in consideration of these circumstances, and has as its objective the stable continuation of hot gas heating mode while suppressing fluctuations in blowing temperature when transitioning from hot gas heating mode to endothermic heating mode, thereby improving passenger comfort. [Means for solving the problem]

[0009] The present invention relates to an air conditioning unit having a refrigerant circuit including a compressor, an indoor heat exchange unit, an external heat exchange unit, and a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor without passing through the indoor heat exchange unit and the external heat exchange unit, and an air conditioning unit having an air blower and an air damper that adjusts the proportion of air blown by the blower to the indoor heat exchange unit; an endothermic heating mode that controls the refrigerant circuit and the air conditioning unit, and causes the refrigerant compressed by the compressor to radiate heat in the indoor heat exchange unit and then absorb heat in the external heat exchanger; and a control device capable of executing a hot gas heating mode in which a portion of the refrigerant that has been absorbed is passed through the hot gas bypass and returned to the compressor, while the remainder is dissipated in heat in the indoor heat exchange section.When transitioning from the hot gas heating mode to the endothermic heating mode, the control device controls the air damper to drive the air damper to reduce the current heating capacity in the hot gas heating mode if the difference between the current heating capacity in the hot gas heating mode and the heating capacity of the endothermic heating mode estimated based on the temperature of the heat absorption target by the external heat exchanger is equal to or greater than a predetermined value. Effect of the Invention

[0010] According to the present invention, the hot gas heating mode can be continued stably, and the fluctuation in blown temperature during the transition from the hot gas heating mode to the endothermic heating mode can be suppressed, thereby improving the comfort of the occupants. [Brief description of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram showing an example of a system configuration of a vehicle air conditioner according to an embodiment of the present invention; [Diagram 2] 1 is an explanatory diagram showing a control device for a vehicle air conditioner according to an embodiment of the present invention; [Diagram 3] 1 is a diagram showing the configuration of a control device and the like in an electric vehicle (EV) according to an embodiment of the present invention. [Figure 4]FIG. 4 is an explanatory diagram showing an operation of the refrigerant circuit in a hot gas heating mode in the vehicle air conditioning system according to the embodiment of the present invention. [Diagram 5] 5 is a flowchart showing a flow of processing performed by a control device in a vehicle air conditioner according to an embodiment of the present invention, with respect to a transition from a hot gas heating mode to a heat absorption heating mode, in a first embodiment. [Figure 6] 6 is a flowchart showing a flow of processing in a second embodiment regarding a transition from a hot gas heating mode to an endothermic heating mode by a control device in a vehicle air conditioner according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] [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.

[0014] The vehicle air conditioner 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21 and 22 provided inside the air conditioning unit 20, and an external heat exchanger 11 provided outside the vehicle cabin, which are arranged along a refrigerant flow path. The indoor heat exchangers 21 and 22 are provided for heat exchange between the air flowing through the air conditioning unit 20 and the refrigerant, and the external heat exchanger 11 is provided for heat exchange between the outside air and the refrigerant outside the vehicle cabin. The indoor heat exchanger 21 is for heating the air, and the indoor heat exchanger 22 is for cooling the air. A refrigerant pressure sensor 44B for detecting an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) and a refrigerant temperature sensor 43B for detecting an outlet refrigerant temperature Tc (high-pressure side refrigerant temperature) from the indoor heat exchanger 21 are provided immediately downstream of the indoor heat exchanger 21.

[0015] The compressor 2 compresses the refrigerant and circulates it through a refrigerant circuit 10. The refrigerant compressed by the compressor 2 is reduced in pressure to a required level by passing through a first pressure reduction section V1, a second pressure reduction section V2, a third pressure reduction section V3, and a fourth pressure reduction section V4, which are, for example, expansion valves, in an appropriately selected refrigerant flow path. The refrigerant circuit 10 is provided with flow path switching valves 12 and 13 for switching the refrigerant flow path, and check valves 14 and 15 for regulating the flow direction of the refrigerant.

[0016] An accumulator 16 that recovers liquid refrigerant and separates the refrigerant into gas and liquid is provided immediately upstream of the compressor 2 in the refrigerant circuit 10. A refrigerant pressure sensor 44A that detects a suction refrigerant pressure Ps (low-pressure side refrigerant pressure) sucked into the compressor 2 and a refrigerant temperature sensor 43A that detects a suction refrigerant temperature Ts (low-pressure side refrigerant temperature) are provided between the accumulator 16 and the compressor 2.

[0017] As described above, the air conditioning unit 20 includes the indoor heat exchangers 21, 22 therein, a blower 23 that introduces air into the unit from inside or outside the vehicle cabin, and an air damper 24 that adjusts the proportion of the air introduced by the blower 23 that passes through the indoor heat exchanger 21. The air conditioning unit 20 also includes an air damper 25 that is provided upstream of the blower 23 in the air inflow direction and switches the air introduced by the blower 23 to either the inside of the vehicle cabin or the outside of the vehicle cabin.

[0018] In the air conditioning unit 20, air introduced by the blower 23 passes through the indoor heat exchangers 21, 22 and is blown into the vehicle cabin. When the air damper 24 shown in Fig. 1 is fully open, the air introduced by the blower 23 passes through the indoor heat exchanger 22 and then the indoor heat exchanger 21 and is blown into the vehicle cabin. When the air damper 24 is fully closed, the inlet side of the indoor heat exchanger 21 is blocked, and the air introduced by the blower 23 passes only through the indoor heat exchanger 22 and is blown into the vehicle cabin.

[0019] In the air conditioning unit 20, air can be taken in from either air inlet 25A connected to the outside or air inlet 25B connected to the inside of the room by selectively closing the air damper 25. Also, in the air conditioning unit 20, air from outside the vehicle cabin or air from outside the vehicle cabin can be taken in at a desired ratio from both air inlet 25A and air inlet 25B by, for example, positioning the air damper 25 at a desired position between 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 60 (such as an air conditioning instruction signal and a charger connection signal) and detection signals from the 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 which detects the power consumption (energy consumption) of the compressor 2, a refrigerant temperature sensor 43 and a refrigerant pressure sensor 44 which detect the state of the refrigerant, an occupant sensor 45 which detects the presence or absence of an occupant in the vehicle cabin, an air outlet temperature sensor 46 which detects the air outlet temperature of the air conditioning unit 20, and an inside air sensor 47 which detects conditions inside the vehicle cabin such as inside air temperature and inside air humidity.

[0024] In particular, the refrigerant temperature sensor 43 includes a refrigerant temperature sensor 43A that detects the intake refrigerant temperature Ts (low-pressure side refrigerant temperature) sucked into the compressor 2, and a refrigerant temperature sensor 43B that detects the outlet refrigerant temperature Tc (high-pressure side refrigerant temperature) of the indoor heat exchanger 21 (see Figure 1).

[0025] The refrigerant pressure sensor 44 also includes a refrigerant pressure sensor 44A that detects a suction refrigerant pressure Ps (low-pressure side refrigerant pressure) sucked into the compressor 2, and a refrigerant pressure sensor 44B that detects an outlet refrigerant pressure Pci (high-pressure side refrigerant pressure) of the indoor heat exchanger 21 (see FIG. 1). These sensors are merely examples, and various sensors that detect information required when the control device 100 performs various controls are provided as the sensor unit 40.

[0026] The control targets of the control device 100 are the compressor 2, the first pressure reducing section V1, the second pressure reducing section V2, the third pressure reducing section V3, the fourth pressure reducing section V4, and the flow path switching valves 12 and 13 in the refrigerant circuit 10, the blower 23, the air dampers 24 and 25 in the air conditioning unit 20, and the circulation pump 31 in the heat medium circuit 30. The control device 100 also controls the vehicle air conditioner 1 according to the processing results of the control device 100. The vehicle air conditioner 1 can execute various operation modes by the control device 100, including a heat absorbing heating mode in which the refrigerant is caused to absorb heat in the external heat exchanger 11, and a hot gas heating mode in which the refrigerant compressed by the compressor 2 is caused to dissipate heat in the indoor heat exchanger 21 without the refrigerant absorbing heat in the external heat exchanger 11 to heat the vehicle interior.

[0027] [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.

[0028] 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).

[0029] 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.

[0030] 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.

[0031] 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.

[0032] [Hot gas heating mode] At extremely low temperatures, it is difficult for the external heat exchanger 11 to absorb heat, so the hot gas heating mode is used. The hot gas heating mode is an operation mode in which the refrigerant 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.

[0033] The operation of the refrigerant circuit 10 in the hot gas heating mode will be described with reference to Fig. 4. In this operation, part of the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 and the flow path switching valve 12, is depressurized in the third pressure reduction section V3 to become a low-pressure refrigerant, passes through the refrigerant heat medium heat exchanger 34, is separated into gas and liquid in the accumulator 16, and returns to the compressor 2. At this time, in the refrigerant circuit 10, the first pressure reduction section V1 is fully closed, so that the refrigerant does not flow to the external heat exchanger 11. Also, the fourth pressure reduction section V4 is fully closed, so that the refrigerant does not flow to the indoor heat exchanger 22.

[0034] 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.

[0035] 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, 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.

[0036] In the hot gas heating mode, the refrigerant flowing through the refrigerant circuit 10 is decompressed in the third decompression section V3 in the flow path that passes through the indoor heat exchanger 21, so that the refrigerant upstream of that section becomes a high-pressure refrigerant and the refrigerant downstream of that section becomes a low-pressure refrigerant. At this time, it is important in order to maintain the heating capacity that heat exchange is not performed in the refrigerant-heat medium heat exchanger 34 in the low-pressure side flow path. In the air conditioning unit 20, the air introduced by the blower 23 is heated by heat dissipation in the indoor heat exchanger 21 and is blown into the vehicle cabin.

[0037] [Endothermic heating mode] In the endothermic heating mode, the refrigerant in the refrigerant circuit 10 is caused to flow through the external heat exchanger 11 as described below, so that the refrigerant absorbs heat from the outside air, which is the heat absorption target, to obtain a heat source for heating. Note that the flow of the refrigerant in the refrigerant circuit 10 in the endothermic heating mode is not shown in the drawings.

[0038] In the refrigerant circuit 10 in the endothermic heating mode, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valve 12 are fully closed. On the other hand, the flow path switching valve 13 is fully open, and the first pressure reduction section V1 is open.

[0039] In the endothermic heating mode, the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 in the air conditioning unit 20 and is depressurized in the first depressurization section V1, and the low-pressure refrigerant passes through the external heat exchanger 11 and is returned to the compressor 2 via the flow path switching valve 13, the check valve 14, and the accumulator 16. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the indoor heat exchanger 21, is depressurized in the first depressurization section V1 to become a low-pressure refrigerant, absorbs heat and evaporates in the external heat exchanger 11, and returns to the compressor 2. In the air conditioning unit 20, the air introduced by the blower 23 is heated by the heat released in the indoor heat exchanger 21 and is blown into the vehicle cabin.

[0040] [Operation mode switching control by control device] Hereinafter, the operation mode switching control by the control device 100 in the case where the vehicle air conditioner 1 according to this embodiment heats the vehicle cabin will be described. When the vehicle air conditioner 1 heats the vehicle interior, the control device 100 executes either the endothermic heating mode or the hot gas heating mode depending on the external environment such as the outside air temperature Tam, the set temperature Tset, etc. Since the hot gas heating mode has a higher heating capacity than the endothermic heating mode, the control device 100 normally executes the endothermic heating mode when the outside air temperature Tam is equal to or higher than a predetermined temperature (e.g., -10°C), and executes the hot gas heating mode when the outside air temperature Tam is an extremely low temperature environment below the predetermined temperature.

[0041] On the other hand, for example, when the vehicle air conditioning system 1 is started in an external environment where the outside air temperature Tam is within a specified temperature range including the aforementioned specified temperature and both the endothermic heating mode and the hot gas heating mode can be executed, the control device 100 can control the system to execute the hot gas heating mode at startup and then transition to the endothermic heating mode. By controlling in this manner, the temperature inside the vehicle cabin can be raised as quickly as possible using the hot gas heating mode to ensure immediate heating, and then, when the temperature inside the vehicle cabin reaches a target temperature (for example, the set temperature Tset described below), the mode is switched to endothermic heating mode to reduce power consumption.

[0042] However, since there is a difference in heating capacity between the hot gas heating mode and the endothermic heating mode as described above, there is a risk that the temperature of the air blown into the vehicle cabin will change significantly when transitioning from the hot gas heating mode to the endothermic heating mode. Therefore, the control device 100 controls the transition from the hot gas heating mode to the endothermic heating mode to reduce the difference in heating capacity between the two modes, thereby suppressing fluctuations in the air blown temperature caused by the difference in heating capacity.

[0043] The process of transitioning from the hot gas heating mode to the endothermic heating mode by the control device 100 of the vehicle air conditioner 1 according to this embodiment will be described below with reference to the flowcharts of Figures 5 and 6. In the following description, in order to reduce the difference in heating capacity, in the example shown in Figure 5, the control device 100 mainly controls the air damper 24 (Example 1), and in the example shown in Figure 6, the control device 100 mainly controls the compressor 2 and the air damper 24 (Example 2).

[0044] Example 1 5, when the vehicle air conditioner 1 starts heating the vehicle cabin, the hot gas heating mode is executed (step S11). In the refrigerant circuit 10, the control device 100 fully closes the first pressure reduction part V1 and the fourth pressure reduction part V4, and opens the second pressure reduction part V2 and the third pressure reduction part V3. In this state, the control device 100 drives the compressor 2 to cause a portion of the high-temperature, high-pressure refrigerant discharged from the compressor 2 to flow to the indoor heat exchanger 21 to exchange heat with the air to be supplied into the vehicle cabin, and then to return the portion to the compressor 2, and causes the remaining high-temperature, high-pressure refrigerant discharged from the compressor 2 to flow through the hot gas bypass 10V and return to the compressor 2.

[0045] At this time, in order to stabilize the operating conditions of the hot gas heating mode, it is desirable to set the ratio of inside and outside air to a fixed ratio using the air damper 25 (for example, a ratio of 20% outside air and 80% inside air to suppress an increase in carbon dioxide concentration and take into account clear windows).

[0046] During execution of the hot gas heating mode, the control device 100 compares the set temperature Tset with an interior temperature Tin, which is the temperature inside the vehicle cabin acquired at a predetermined cycle from the interior air sensor 47, and monitors whether the interior temperature is equal to the set temperature Tset (step S12). In the process of step S12, the control device 100 defines a predetermined temperature range including the set temperature Tset as an allowable temperature range, and can regard the interior temperature Tin as equal to the set temperature Tset if it is within the allowable temperature range.

[0047] If the indoor temperature Tin is not within the allowable temperature range including the set temperature Tset (NO in step S12), the control device 100 continues the hot gas heating mode. On the other hand, if the indoor temperature Tin is within the allowable temperature range including the set temperature Tset (YES in step S12), the control device 100 proceeds to step S13.

[0048] In step S13, the control device 100 determines whether it is preferable to transition from the hot gas heating mode to the endothermic heating mode (step S13). In this determination, the control device 100 determines whether it is preferable to transition the operation mode in order to reduce the power consumption of the vehicle air conditioner 1, taking into account the outside air temperature Tam, the indoor temperature Tin, and the operating state and current heating capacity of the hot gas heating mode. If the control device 100 does not transition the operation mode (NO in step S13), it continues the hot gas heating mode and monitors whether the indoor temperature is equal to the set temperature Tset (step S12).

[0049] When the control device 100 determines that the hot gas heating mode should be transitioned to the endothermic heating mode (YES in step S13), the control device 100 proceeds to step S14. When the control device 100 determines that the hot gas heating mode should be transitioned to the endothermic heating mode, the control device 100 preferably controls the air damper 25 so that the ratio of inside air is higher than the ratio of inside / outside air in the above-mentioned step S11. By increasing the ratio of inside air, the heating load can be reduced.

[0050] In step S14, the current heating capacity in the hot gas heating mode and the heating capacity in the endothermic heating mode estimated based on the outside air temperature Tam, which is the heat absorption target of the external heat exchanger 11, are acquired, the difference between these heating capacities (hereinafter, the difference value ΔQ) is calculated, and it is determined whether the difference value ΔQ is equal to or greater than a predetermined value Qth. If the difference value ΔQ is equal to or greater than the predetermined value Qth (YES in step S14), the control device 100 drives the air damper 24 to reduce the difference value ΔQ, that is, to reduce the heating capacity in the hot gas heating mode (step S15). If the difference value ΔQ is less than the predetermined value Qth (NO in step S14), the mode is transitioned to the endothermic heating mode (step S17).

[0051] When the hot gas heating mode and the endothermic heating mode are compared for the range of heating capacity obtained by controlling the compressor 2, the minimum heating capacity in the hot gas heating mode and the maximum heating capacity in the endothermic heating mode do not overlap with each other, and the minimum heating capacity in the hot gas heating mode is higher than the maximum heating capacity in the endothermic heating mode. Therefore, in step S15, the control device 100 controls the air damper 24 to reduce the proportion of air sent to the indoor heat exchanger 21, thereby reducing the heating capacity in the hot gas heating mode and reducing the difference value ΔQ.

[0052] By controlling air damper 24 in this manner, the proportion of air sent to the flow path that bypasses indoor heat exchanger 21 is increased, thereby lowering the temperature blown into the vehicle cabin. Therefore, by controlling air damper 24, in addition to reducing difference value ΔQ, it is possible to lower the blown temperature in the hot gas heating mode, thereby suppressing large fluctuations when the operation mode is changed.

[0053] The control device 100 monitors the difference value ΔQ while driving the air damper 24 (step S16), and drives the air damper 24 until the difference value ΔQ becomes less than a predetermined value Qth (NO in step S16). When the difference value ΔQ becomes less than the predetermined value Qth (YES in step S16), the control device 100 transitions from the hot gas heating mode to the endothermic heating mode (step S17).

[0054] Thus, in the vehicle air conditioner 1 according to this embodiment, when transitioning from the hot gas heating mode to the endothermic heating mode, the control device 100 controls the difference between the heating capacity of the hot gas heating mode and the heating capacity of the endothermic heating mode to be small. This makes it possible to suppress a large fluctuation in the blown temperature caused by the difference in heating capacity, and improve the comfort of the occupants. In particular, since the control device 100 controls the air damper 24 to reduce the difference in heating capacity, the operating state of the hot gas heating mode does not fluctuate greatly, and a smooth transition to the endothermic heating mode can be made while stably continuing the hot gas heating mode.

[0055] Example 2 6, when the vehicle air conditioner 1 starts heating the vehicle cabin, the hot gas heating mode is executed (step S21). In the refrigerant circuit 10, the control device 100 fully closes the first pressure reduction part V1 and the fourth pressure reduction part V4, and opens the second pressure reduction part V2 and the third pressure reduction part V3. In this state, the control device 100 drives the compressor 2 to cause a portion of the high-temperature, high-pressure refrigerant discharged from the compressor 2 to flow to the indoor heat exchanger 21 to exchange heat with the air to be supplied to the vehicle cabin, and then to return the refrigerant to the compressor 2, and causes the remaining high-temperature, high-pressure refrigerant discharged from the compressor 2 to flow through the hot gas bypass 10V and return it to the compressor 2.

[0056] At this time, in order to stabilize the operating conditions of the hot gas heating mode, it is desirable to set the ratio of inside and outside air to a fixed ratio using the air damper 25 (for example, a ratio of 20% outside air and 80% inside air to suppress an increase in carbon dioxide concentration and take into account clear windows).

[0057] During execution of the hot gas heating mode, the control device 100 compares the set temperature Tset with an interior temperature Tin, which is the temperature inside the vehicle cabin acquired at a predetermined cycle from the interior air sensor 47, and monitors whether the interior temperature is equal to the set temperature Tset (step S22). In the process of step S22, the control device 100 defines a predetermined temperature range including the set temperature Tset as an allowable temperature range, and can regard the interior temperature Tin as equal to the set temperature Tset if it is within the allowable temperature range.

[0058] If the indoor temperature Tin is not within the allowable temperature range including the set temperature Tset (NO in step S22), the control device 100 continues the hot gas heating mode. On the other hand, if the indoor temperature Tin is within the allowable temperature range including the set temperature Tset (YES in step S22), the control device 100 proceeds to step S23. In step S23, the control device 100 gradually or stepwise reduces the rotation speed TGNC of the compressor 2 to reduce the current heating capacity in the hot gas heating mode.

[0059] The hot gas heating mode can continue stable operation by maintaining a balance between the amount of heat input and the amount of heat dissipation in the refrigerant circuit 10, and there is a lower limit to the rotation speed TGNC of the compressor 2 that is necessary to maintain this balance. The control device 100 calculates a minimum rotation speed TGNC_LL, which is the lower limit of the rotation speed TGNC of the compressor 2 that can stably continue the operating state in the hot gas heating mode, or stores this in advance in, for example, ROM 102.

[0060] Therefore, the control device 100 monitors whether the rotation speed TGNC of the compressor 2 has reached the minimum rotation speed TGNC_LL so that the rotation speed TGNC does not fall below the minimum rotation speed TGNC_LL (step S24). The control device 100 reduces the rotation speed TGNC of the compressor 2 until it becomes the minimum rotation speed TGNC_LL (NO in step S24), and proceeds to step S25 when the rotation speed TGNC becomes the minimum rotation speed TGNC_LL (YES in step S24). In this way, the heating capacity in the hot gas heating mode can be reduced as much as possible by controlling the compressor 2, while the operating state in the hot gas heating mode can be stably continued.

[0061] In step S25, the control device 100 determines whether it is preferable to transition from the hot gas heating mode to the endothermic heating mode (step S25). That is, in this determination, the control device 100 determines whether it is preferable to transition the operation mode in order to reduce the power consumption of the vehicle air conditioner 1, particularly in consideration of the outside air temperature Tam, the room temperature Tin, and the operating state and current heating capacity of the hot gas heating mode. If the control device 100 does not transition the operation mode (NO in step S25), it continues the hot gas heating mode (step S22).

[0062] When the control device 100 determines in step S25 that the hot gas heating mode should be transitioned to the endothermic heating mode (YES in step S25), the control device 100 proceeds to step S26. When the control device 100 determines that the hot gas heating mode should be transitioned to the endothermic heating mode, it preferably controls the air damper 25 so that the inside air ratio is higher than the inside / outside air ratio in the above-mentioned step S21. By increasing the inside air ratio, the heating load can be reduced.

[0063] In step S26, the current heating capacity in the hot gas heating mode and the heating capacity in the endothermic heating mode estimated based on the outside air temperature Tam, which is the target of heat absorption by the external heat exchanger 11, are obtained, the difference between these heating capacities (hereinafter, the difference value ΔQ) is calculated, and it is determined whether the difference value ΔQ is greater than or equal to a predetermined value Qth.

[0064] In this embodiment, the rotation speed TGNC of the compressor 2 is reduced to the minimum rotation speed TGNC_LL in the hot gas heating mode, so the current heating capacity in the hot gas heating mode acquired in step S26 is the lowest heating capacity that can be achieved by controlling the rotation speed TGNC of the compressor 2. When transitioning from this state to the endothermic heating mode, if the difference value ΔQ is equal to or greater than a predetermined value Qth (YES in step S26), the control device 100 drives the air damper 24 to reduce the difference value ΔQ, that is, to reduce the heating capacity in the hot gas heating mode (step S27). If the difference value ΔQ is less than the predetermined value Qth (NO in step S26), transition is made to the endothermic heating mode (step S29).

[0065] As mentioned above, when comparing the range of heating capacity obtained by controlling compressor 2 in hot gas heating mode and endothermic heating mode, the minimum heating capacity in hot gas heating mode and the maximum heating capacity in endothermic heating mode do not overlap, and the minimum heating capacity in hot gas heating mode is higher than the maximum heating capacity in endothermic heating mode.

[0066] In this embodiment, the rotation speed TGNC of the compressor 2 is reduced to the minimum rotation speed TGNC_LL, so that in step S27, the control device 100 controls the air damper 24 so as to reduce the proportion of air blown to the indoor heat exchanger 21, thereby further reducing the heating capacity in the hot gas heating mode and reducing the difference value ΔQ.

[0067] By controlling air damper 24 in this manner, the proportion of air sent to the flow path that bypasses indoor heat exchanger 21 is increased, thereby lowering the temperature blown into the vehicle cabin. Therefore, by controlling air damper 24, in addition to reducing difference value ΔQ, it is possible to lower the blown temperature in the hot gas heating mode, thereby suppressing large fluctuations when the operation mode is changed.

[0068] The control device 100 monitors the difference value ΔQ while driving the air damper 24 (step S28), and drives the air damper 24 until the difference value ΔQ becomes less than the predetermined value Qth (NO in step S28). When the difference value ΔQ becomes less than the predetermined value Qth (YES in step S28), the control device 100 transitions from the hot gas heating mode to the endothermic heating mode (step S29).

[0069] In this way, in the vehicle air conditioner 1 according to this embodiment, when transitioning from the hot gas heating mode to the endothermic heating mode, the control device 100 controls the difference between the heating capacity in the hot gas heating mode and the heating capacity in the endothermic heating mode to be small. This makes it possible to suppress large fluctuations in the outlet temperature caused by the difference in heating capacity, thereby improving the comfort of the occupants.

[0070] The control device 100 reduces the heating capacity as much as possible by controlling the rotation speed TGNC of the compressor 2, and further controls the air damper 24 to reduce the difference in heating capacity. Therefore, the operating state of the hot gas heating mode does not fluctuate significantly, and the hot gas heating mode can be stably continued while smoothly transitioning to the endothermic heating mode, thereby improving the comfort of the passengers.

[0071] As described above, according to this embodiment, the hot gas heating mode is continued stably, and fluctuations in the blown air temperature when transitioning from the hot gas heating mode to the endothermic heating mode are suppressed, thereby improving the comfort of the occupants.

[0072] 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]

[0073] 1: vehicle air conditioning system, 2: compressor, 10: refrigerant circuit, 10V: hot gas bypass 11: external heat exchanger, 12, 13: flow path switching valve, 14, 15: check valve 16: accumulator, 20: air conditioning unit, 21, 22: indoor heat exchanger 23: blower, 24, 25: air damper, 25A, 25B: air inlet 30: Heat medium circuit, 31: Circulation pump, 33: Heat exchanger to be temperature-controlled 34: refrigerant / heat medium heat exchanger, 34A, 34B: flow path, 40: sensor unit 41: Outdoor air sensor, 42: Compressor current sensor 43, 43A, 43B: refrigerant temperature sensor, 44, 44A, 44B: refrigerant pressure sensor 45: occupant sensor, 46: blower temperature sensor, 47: inside air sensor, 60: input signal 100: Control device

Claims

1. a refrigerant circuit including a compressor, an indoor heat exchange unit, an external heat exchange unit, and a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor and returns it to the compressor without passing through the indoor heat exchange unit and the external heat exchange unit; an air conditioning unit having the indoor heat exchanger disposed therein, the air conditioning unit including a blower and an air damper that adjusts a ratio of air blown by the blower to the indoor heat exchanger; a control device that controls the refrigerant circuit and the air conditioning unit, and is capable of executing an endothermic heating mode in which the refrigerant compressed by the compressor is made to radiate heat in the indoor heat exchange section and then absorb heat in the external heat exchange section, and a hot gas heating mode in which a portion of the refrigerant compressed by the compressor is made to flow through the hot gas bypass and returned to the compressor, and the remainder is made to radiate heat in the indoor heat exchange section, The control device includes: When transitioning from hot gas heating mode to endothermic heating mode, When the difference between the current heating capacity in the hot gas heating mode and the heating capacity in the endothermic heating mode estimated based on the temperature of the heat absorption target by the external heat exchanger is equal to or greater than a predetermined value, The vehicle air conditioner controls the air damper to reduce the current heating capacity in the hot gas heating mode.

2. The control device includes: When transitioning from hot gas heating mode to endothermic heating mode, In the hot gas heating mode, when the difference between the heating capacity when the compressor is driven at a preset minimum rotation speed and the heating capacity of the heat absorption heating mode estimated based on the temperature of the heat absorption target by the external heat exchanger is equal to or greater than a predetermined value, 2. The vehicle air conditioner according to claim 1, wherein the compressor is driven at a minimum rotation speed and the air damper is driven to reduce a current heating capacity in the hot gas heating mode.

3. The control device includes:

3. The vehicle air conditioner according to claim 1, wherein the air damper is controlled so as to reduce a proportion of the air sent to the indoor heat exchanger.

4. The air conditioning unit has an inside / outside air switching damper that controls a ratio of the air introduced into the vehicle compartment and the air introduced outside the vehicle compartment, The control device includes:

3. The vehicle air conditioner according to claim 1, wherein the ratio of air introduced into the passenger compartment is increased by the inside / outside air switching damper when the mode is changed from the hot gas heating mode to the endothermic heating mode.

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