Air conditioning device and control method of air conditioning device

Abstract

A vehicle air-conditioning device (100) is provided with: a circulation flow path that guides a refrigerant that has passed through a heating unit (20) to an accumulator (30); a bypass flow path that guides the refrigerant to the accumulator (30) without passing through the heating unit (20); and a control unit (90) that controls the degree of opening of the expansion valve (40) disposed in the circulation flow path and the degree of opening of the expansion valve (50) disposed in the bypass flow path, the control unit (90) controlling the degree of opening of the expansion valve (40) and the degree of opening of the expansion valve (50) such that when the pressure of the refrigerant sucked in by the compressor (10) is lower than a predetermined pressure, the expansion valve (40) and the expansion valve (50) are opened. When the pressure of the refrigerant sucked into the compressor (10) is higher than a predetermined pressure, the ratio of the gas refrigerant in the inflow refrigerant flowing into the accumulator (30) is greater than the ratio of the gas refrigerant in the outflow refrigerant flowing out of the accumulator (30). The proportion of the liquid refrigerant in the inflow refrigerant is greater than the proportion of the liquid refrigerant in the outflow refrigerant.

Description

Technical Field

[0001] The invention relates to an air conditioning device and a control method of the air conditioning device. Background Art

[0002] Conventionally, it is known that in a heat pump type vehicle air conditioner, in order to prevent frost formation on the outdoor heat exchanger, an anti-frost operation is performed in which high-temperature and high-pressure gas ejected from the compressor without passing through the outdoor heat exchanger circulates between the cabin heat exchanger, the accumulator, and the compressor (for example, refer to Patent Document 1). Patent Document 1 discloses the following technology: when the pressure on the downstream side of the outdoor heat exchanger becomes lower than a predetermined pressure, it is determined that the heat exchange capacity of the outdoor heat exchanger is reduced due to the adhesion of frost, and a heat pump operation is performed in a refrigerant circuit that does not use the outdoor heat exchanger. Previous technical literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2000-343934 Summary of the invention Technical issues to be solved by the invention

[0004] However, when the heat pump is operated in a refrigerant circuit without using an outdoor heat exchanger, the lower the pressure of the refrigerant flowing from the accumulator into the compressor is compared to the desired pressure, the lower the suction density of the refrigerant is, which leads to a decrease in the power of the compressor. In addition, the higher the pressure of the refrigerant flowing from the accumulator into the compressor is compared to the desired pressure, the higher the suction density of the refrigerant is, which leads to an increase in the torque required to operate the compressor at the desired rotation speed.

[0005] The present invention is completed in view of this situation, and its purpose is to provide an air-conditioning device and a control method for the air-conditioning device that can suppress the reduction in compressor power caused by the pressure reduction of the refrigerant flowing into the compressor and the increase in compressor torque caused by the pressure increase of the refrigerant flowing into the compressor. Means for solving technical problems

[0006] In order to solve the above-mentioned problems, the present invention adopts the following means. The air conditioning device of the present invention comprises: a compressor for compressing a refrigerant; a heating unit for heating a heating object by using the refrigerant ejected from the compressor; an accumulator for separating a liquid component from the refrigerant sucked into the compressor; a circulation flow path for guiding the refrigerant that has passed through the heating unit to the accumulator; a bypass flow path for guiding the refrigerant ejected from the compressor without passing through the heating unit to the accumulator; a first expansion mechanism disposed in the circulation flow path for expanding the refrigerant that has flowed out from the heating unit; a second expansion mechanism disposed in the bypass flow path for expanding the refrigerant ejected from the compressor; and a control unit for controlling the first expansion mechanism and the second opening of the second expansion mechanism, the control unit controls the first opening and the second opening in the following manner: when the pressure of the refrigerant sucked by the compressor is lower than a specified pressure, the ratio of the gas refrigerant in the inflowing refrigerant including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism flowing into the accumulator is made greater than the ratio of the gas refrigerant in the outflowing refrigerant flowing out of the accumulator; and when the pressure of the refrigerant sucked by the compressor is higher than the specified pressure, the ratio of the liquid refrigerant in the inflowing refrigerant is made greater than the ratio of the liquid refrigerant in the outflowing refrigerant flowing out of the accumulator.

[0007] In the control method of the air-conditioning device involved in the present invention, the air-conditioning device comprises: a compressor that compresses refrigerant; a heating unit that heats a heating object by the refrigerant ejected from the compressor; an accumulator that separates a liquid component in the refrigerant sucked by the compressor; a circulation flow path that guides the refrigerant that has passed through the heating unit to the accumulator; a bypass flow path that guides the refrigerant ejected from the compressor without passing through the heating unit to the accumulator; a first expansion mechanism that is arranged in the circulation flow path and expands the refrigerant that has flowed out of the heating unit; and a second expansion mechanism that is arranged in the bypass flow path and expands the refrigerant ejected from the compressor. The control method of the air-conditioning device comprises: a first control step, The first opening degree of the first expansion mechanism and the second opening degree of the second expansion mechanism are controlled in the following manner, i.e., when the pressure of the refrigerant sucked by the compressor is lower than a specified pressure, the proportion of gas refrigerant in the inflowing refrigerant including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism flowing into the accumulator is made greater than the proportion of gas refrigerant in the outflowing refrigerant flowing out of the accumulator; and a second control step is to control the first opening degree and the second opening degree in the following manner, i.e., when the pressure of the refrigerant sucked by the compressor is higher than the specified pressure, the proportion of liquid refrigerant in the inflowing refrigerant is made greater than the proportion of liquid refrigerant in the outflowing refrigerant flowing out of the accumulator. Effects of the Invention

[0008] According to the present invention, an air conditioning device and a control method of the air conditioning device can be provided, which can suppress a decrease in compressor power due to a decrease in refrigerant pressure flowing into the compressor and an increase in compressor torque due to an increase in refrigerant pressure flowing into the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a refrigerant circuit diagram of a vehicle air conditioning system according to one embodiment of the present invention. Figure 2 This is a refrigerant circuit diagram showing the flow of refrigerant during the heat pump heating operation of the vehicle air conditioner. Figure 3 This is a refrigerant circuit diagram showing the flow of refrigerant during hot air heating operation of the vehicle air conditioner. Figure 4 This is a flowchart showing the operation of the vehicle air conditioner during hot air heating operation. Figure 5 This is a flowchart showing the operation of the vehicle air conditioner during hot air heating operation. Figure 6 This is a Mollier diagram showing the state of the refrigerant during hot gas heating operation. Figure 7 This is a refrigerant circuit diagram showing the flow of refrigerant during the dehumidification and heating operation of the vehicle air conditioner. Figure 8 This is a refrigerant circuit diagram showing the flow of refrigerant during cooling operation of the vehicle air conditioner. DETAILED DESCRIPTION

[0010] Below, reference Figure 1 , a heat pump type vehicle air conditioner (air conditioner) 100 according to an embodiment of the present invention will be described. Figure 1 As shown, the vehicle air conditioning device 100 of the present embodiment includes a compressor 10, a heating unit 20, an accumulator 30, an expansion valve (first expansion mechanism) 40, an expansion valve (second expansion mechanism) 50, an opening and closing valve (switching unit) 61, an opening and closing valve (switching unit) 62, an opening and closing valve 63, an opening and closing valve (first opening and closing valve) 64, an opening and closing valve (second opening and closing valve) 65, an expansion valve (third expansion mechanism) 70, an outdoor heat exchanger 80, an outdoor fan 81, a cabin heat exchanger (evaporator) 85, a cabin blower 86, a control unit 90, a refrigerant heater 91, a pressure sensor 92, a temperature sensor 93, a temperature sensor 94, a temperature sensor 95 and a pressure sensor 96.

[0011] The vehicle air conditioning device 100 of the present embodiment generates warm air by a heating unit 20 provided in the vehicle, or generates cold air by a cabin heat exchanger 85 provided in the vehicle, and blows the air into the vehicle. The vehicle air conditioning device 100 operates the outdoor heat exchanger 80 as an evaporator during heat pump heating operation, and operates the outdoor heat exchanger 80 as a condenser during cooling operation. Furthermore, when the outside air temperature is below a predetermined temperature (e.g., -20°C), the vehicle air conditioning device 100 can perform hot air heating operation for heating only by the power of the compressor 10, without passing the refrigerant through the outdoor heat exchanger 80. The refrigerant used in the vehicle air conditioning device 100 of the present embodiment is, for example, HFO-1234yf.

[0012] The compressor 10 is a device that compresses the refrigerant flowing in from the accumulator 30. The compressor 10 is, for example, an electric compressor that compresses the refrigerant by driving a motor (not shown). The compressor 10 compresses the refrigerant flowing in from the refrigerant pipe L1 and discharges it to the refrigerant pipe L2. The refrigerant discharged to the refrigerant pipe L2 is guided to the heating unit 20 via the refrigerant pipe L3 and the refrigerant pipe L4.

[0013] The heating unit 20 is a device that heats the air (heating object) blown by the cabin blower 86 using the high-temperature and high-pressure refrigerant ejected from the compressor 10. The air heated by the heating unit 20 is blown into the vehicle interior. The refrigerant that has exchanged heat with the air in the heating unit 20 is guided to the expansion valve 40 disposed in the refrigerant piping L5.

[0014] The accumulator 30 is a device that separates at least a part of the liquid component in the refrigerant sucked into the compressor 10. The accumulator 30 guides the gas phase or gas-liquid two-phase refrigerant to the compressor 10 via the refrigerant pipe L1.

[0015] The expansion valve 40 is disposed in the refrigerant pipe L5 and is a mechanism for expanding the refrigerant flowing out of the heating unit 20. The opening degree of the expansion valve 40 is controlled by the control unit 90. The refrigerant expanded by the expansion valve 40 flows through the refrigerant pipe L5.

[0016] The expansion valve 50 is disposed in the refrigerant pipe L6 connected to the refrigerant pipe L3, and is a mechanism for expanding the refrigerant discharged from the compressor 10. The opening of the expansion valve 50 is controlled by the control unit 90. The refrigerant expanded by the expansion valve 50 is guided from the refrigerant pipe L6 to the accumulator 30 via the refrigerant pipe L7. The refrigerant pipe L7 is a pipe connecting the cabin heat exchanger 85 and the accumulator 30.

[0017] The on-off valve 61 is a device disposed on the refrigerant piping L8, and switches between an open state in which the refrigerant flows through the refrigerant piping L8 and a closed state in which the refrigerant does not flow through the refrigerant piping L8. The refrigerant piping L8 is a pipe connecting the refrigerant piping L5 and the refrigerant piping L9. The refrigerant piping L9 is a pipe connecting the refrigerant piping L10 and the refrigerant piping L7. The refrigerant piping L10 is a pipe connecting the outdoor heat exchanger 80 and the cabin heat exchanger 85.

[0018] The on-off valve 62 is a device disposed in the refrigerant pipe L6 and switches between an open state in which the refrigerant is allowed to flow through the refrigerant pipe L6 and a closed state in which the refrigerant is not allowed to flow through the refrigerant pipe L6 . The on-off valve 63 is a device disposed in the refrigerant pipe L11 and switches between an open state in which the refrigerant is allowed to flow through the refrigerant pipe L11 and a closed state in which the refrigerant is not allowed to flow through the refrigerant pipe L11 .

[0019] The on-off valve 64 is arranged on the refrigerant piping L5, and is a device that switches between an open state in which the refrigerant flows toward the outdoor heat exchanger 80 side that is closer to the connection portion of the refrigerant piping L5 with the refrigerant piping L8, and a closed state in which the refrigerant does not flow toward the outdoor heat exchanger 80 side that is closer to the connection portion of the refrigerant piping L5 with the refrigerant piping L8. The on-off valve 65 is a device disposed in the refrigerant pipe L9 and switches between an open state in which the refrigerant is allowed to flow through the refrigerant pipe L9 and a closed state in which the refrigerant is not allowed to flow through the refrigerant pipe L9 .

[0020] The expansion valve 70 is disposed in the refrigerant pipe L10 and is a mechanism for expanding the refrigerant introduced from the outdoor heat exchanger 80. The opening degree of the expansion valve 70 is controlled by the control unit 90. The refrigerant expanded by the expansion valve 70 is guided to the cabin heat exchanger 85 from the refrigerant pipe L10.

[0021] The outdoor heat exchanger 80 is a device that is disposed outside the vehicle and performs heat exchange between the outside air and the refrigerant. The outdoor heat exchanger 80 acts as an evaporator when the heat pump is in heating operation, and evaporates the refrigerant to cool the outside air. In addition, the outdoor heat exchanger 80 acts as a condenser when the cooling operation is in operation, and condenses the refrigerant to heat the outside air. The outdoor fan 81 is a device that blows the outside air to the outdoor heat exchanger 80 to promote the heat exchange between the outside air and the refrigerant.

[0022] The cabin heat exchanger (evaporator) 85 is a device that passes through the outdoor heat exchanger 80 and evaporates the refrigerant expanded by the expansion valve 70 to cool or dehumidify the air. The cabin blower 86 blows air to the cabin heat exchanger 85, and guides the air cooled or dehumidified by the cabin heat exchanger 85 into the vehicle interior via the heating unit 20.

[0023] The control unit 90 is a device that controls each unit of the vehicle air conditioner 100. The control unit 90 reads and executes a control program stored in a storage unit (not shown) to perform various processes for controlling each unit of the vehicle air conditioner 100.

[0024] The refrigerant heater 91 is a device disposed on the downstream side of the on-off valve 61 of the refrigerant pipe L8, and heats the refrigerant flowing into the accumulator 30. For example, when the hot air heating operation is started, the control unit 90 operates the refrigerant heater 91 to heat the refrigerant in order to increase the pressure of the refrigerant sucked by the compressor 10.

[0025] The pressure sensor 92 is a sensor for detecting the pressure of the refrigerant flowing through the refrigerant pipe L1. The temperature sensor 93 is a sensor for detecting the temperature of the refrigerant flowing through the refrigerant pipe L1. The temperature sensor 94 is a sensor for detecting the temperature of the refrigerant flowing through the refrigerant pipe L2. The temperature sensor 95 is a sensor for detecting the temperature of the refrigerant flowing through the refrigerant pipe L5 between the heating unit 20 and the expansion valve 40. The pressure sensor 96 is a sensor for detecting the pressure of the refrigerant flowing through the refrigerant pipe L5 between the heating unit 20 and the expansion valve 40.

[0026] In the present embodiment, both the pressure sensor 92 and the temperature sensor 93 are provided on the refrigerant pipe L1, but other methods are also possible. For example, only the temperature sensor 93 may be provided on the refrigerant pipe L1, and the pressure of the refrigerant flowing in the refrigerant pipe L1 may be detected (estimated) based on the temperature detected by the temperature sensor 93.

[0027] <Heat pump heating operation> refer to Figure 2 Next, the operation of the vehicle air conditioning device 100 according to the present embodiment during the heat pump heating operation will be described. Figure 2 1 is a refrigerant circuit diagram showing the flow of refrigerant during heat pump heating operation of vehicle air conditioner 100. Heat pump heating operation is performed when the temperature outside the vehicle where outdoor heat exchanger 80 is installed is not lower than a predetermined temperature (eg, -20°C).

[0028] Figure 2 The arrows shown indicate the flow direction of the refrigerant. Figure 2 As shown, during the heat pump heating operation, the refrigerant circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the outdoor heat exchanger 80, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L3, L4, L5, L9, and L7 form a circulation flow path for circulating the refrigerant.

[0029] During the heat pump heating operation, the outdoor heat exchanger 80 operates as an evaporator and evaporates the refrigerant to cool the outside air. During the heat pump heating operation, the control unit 90 opens the on-off valves 64 and 65 and closes the on-off valves 61, 62, and 63.

[0030] <Hot gas heating operation> refer to Figure 3 Next, the operation of the vehicle air conditioning device 100 according to the present embodiment during the hot air heating operation will be described. Figure 3 1 is a refrigerant circuit diagram showing the flow of the refrigerant during the hot gas heating operation of the vehicle air conditioner 100 . Figure 3 The arrows shown indicate the flow direction of the refrigerant. The hot air heating operation is performed, for example, when the temperature outside the vehicle where the outdoor heat exchanger 80 is installed is equal to or lower than a predetermined temperature (for example, -20°C).

[0031] like Figure 3As shown, during the hot air heating operation, a part of the refrigerant circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L3, L4, L5, L8, L9, and L7 form a circulation flow path for circulating the refrigerant. The refrigerant pipes L5, L8, L9, and L7 guide the refrigerant that has passed through the heating unit 20 to the accumulator 30.

[0032] The other part of the refrigerant is guided from the refrigerant pipe L3 to the refrigerant pipe L7 via the refrigerant pipe L6 without flowing through the refrigerant pipes L4, L5, L8, and L9. The refrigerant pipe L6 is a bypass flow path that guides the refrigerant discharged from the compressor 10 without passing through the heating unit 20 to the accumulator 30.

[0033] When performing the hot air heating operation, the control unit 90 closes the on-off valve 64 and the on-off valve 65 to circulate the refrigerant in the circulation flow path formed by the refrigerant pipes L1, L2, L3, L4, L5, L8, L9, and L7. In addition, in the vehicle air conditioning device 100 of the present embodiment, the amount of refrigerant sealed in the refrigerant pipes formed by the refrigerant pipes L1 to L11 is set so that the air can be heated by the heating unit 20 when the on-off valve 64 and the on-off valve 65 are closed.

[0034] Here, reference Figures 4 to 6 , the operation of the vehicle air conditioning device 100 during the hot air heating operation will be described. Figure 4 and Figure 5 1 is a flowchart showing the operation of the vehicle air conditioner 100 during the hot air heating operation. Figure 4 and Figure 5 Each of the steps shown is executed by the control unit 90 . Figure 6 This is a Mollier diagram showing the state of the refrigerant during hot gas heating operation.

[0035] In step S101 , the control unit 90 performs control so that the on-off valves 61 , 63 , 64 , and 65 are in a closed state. In step S102 , the control unit 90 determines whether the refrigerant pressure LP detected by the pressure sensor 92 exceeds a threshold pressure, and if so, proceeds to step S108 , and if not, proceeds to step S103 .

[0036] In step S103, the control unit 90 controls the on-off valve 62 to be in an open state. The control unit 90 controls the on-off valve 62 to be in an open state and operates the compressor 10, so that the total amount of the refrigerant discharged from the compressor 10 is circulated in a manner guided to the accumulator 30 via the refrigerant piping L6. In this way, the control unit 90 sets the vehicle air conditioning device 100 to the first operation mode in which the refrigerant discharged from the compressor 10 is guided to the refrigerant piping L6 instead of to the heating unit 20.

[0037] In step S104, the control unit 90 controls the expansion valve 50 so as to adjust the opening degree. Step S104 is executed when the determination result in step S102 is "No", which is a state in which the refrigerant pressure LP detected by the pressure sensor 92 is below the threshold pressure and the hot gas heating operation using the heating unit 20 cannot be performed.

[0038] Therefore, in step S104, in order to set the state in which the hot gas heating operation using the heating unit 20 can be performed, the opening of the expansion valve 50 is adjusted to adjust the flow rate of the refrigerant guided to the accumulator 30 through the refrigerant pipe L6. The control unit 90 controls the opening of the expansion valve 50 in such a manner that the larger the difference between the pressure LP of the refrigerant detected by the pressure sensor 92 and the threshold pressure, the larger the opening of the expansion valve 50. Thus, the startup time required to set the state in which the hot gas heating operation using the heating unit 20 can be performed can be shortened.

[0039] In step S105, the control unit 90 determines whether the refrigerant pressure LP detected by the pressure sensor 92 exceeds the threshold pressure. If yes, the process proceeds to step S106. If no, the opening degree of the expansion valve 50 is adjusted again in step S104.

[0040] In step S106, the control unit 90 adjusts the opening of the expansion valve 40 before opening the on-off valve 61 in step S107. The opening of the expansion valve 40 is adjusted to suppress a decrease in the pressure of the refrigerant circulating in the refrigeration cycle when the on-off valve 61 is opened.

[0041] In step S107, the control unit 90 controls the on-off valve 61 to be in an open state. By opening the on-off valve 61, a part of the refrigerant discharged from the compressor 10 circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the accumulator 30, and the compressor 10.

[0042] In this way, the control unit 90 switches the vehicle air conditioning device 100 from the first operation mode, in which the refrigerant ejected from the compressor 10 is guided to the refrigerant pipe L6 instead of the heating unit 20, to the second operation mode, in which the refrigerant ejected from the compressor 10 is guided to both the heating unit 20 and the refrigerant pipe L6. The on-off valve 61 functions as a switching unit for switching between the first operation mode and the second operation mode. The control unit 90 controls the on-off valve 61 in such a manner as to switch the first operation mode to the second operation mode in response to the pressure of the refrigerant sucked by the compressor 10 exceeding the threshold pressure.

[0043] In step S108, the control unit 90 controls the on-off valve 62 to be in an open state. In step S109, the control unit 90 controls the on-off valve 61 to be in an open state. The control unit 90 opens the on-off valve 62 and the on-off valve 61 and operates the compressor 10, thereby setting a state in which a part of the refrigerant ejected from the compressor 10 is guided to the heating unit 20, and another part of the refrigerant ejected from the compressor 10 is guided from the refrigerant pipe L6 to the accumulator 30 without passing through the heating unit 20.

[0044] In step S110, the control unit 90 adjusts the opening of the expansion valve 40 so that the refrigerant passing through the heating unit 20 becomes liquid refrigerant when performing the hot gas heating operation by guiding the refrigerant to the heating unit 20. Figure 6 The opening of the expansion valve 40 is adjusted so that the degree of subcooling SC, which is the difference between the refrigerant temperature at point b and the refrigerant temperature at point b′ shown, becomes a predetermined value. The control unit 90 calculates the degree of subcooling SC based on the temperature detected by the temperature sensor 95 and the pressure detected by the pressure sensor 96 .

[0045] In step S111, the control unit 90 calculates Figure 6 Specific enthalpy ha, hb, hc of points a, b, and c are shown. The specific enthalpy ha of point a is calculated based on the temperature detected by the temperature sensor 94 and the pressure detected by the pressure sensor 96. The specific enthalpy hb of point b is calculated based on the temperature detected by the temperature sensor 95 and the pressure detected by the pressure sensor 96. The specific enthalpy hc of point c is calculated based on either the temperature detected by the temperature sensor 93 or the pressure detected by the pressure sensor 92 and the rotation speed of the motor driving the compressor 10.

[0046] In step S112 , the control unit 90 calculates the refrigerant flow rate Gr1 of the refrigerant pipe L6 . The refrigerant flow rate Gr1 is calculated based on the opening degree of the expansion valve 50 , the pressure HP at the point a, the pressure LP at the point c, and the temperature detected by the temperature sensor 93 .

[0047] In step S113 , the control unit 90 calculates the refrigerant flow rate Gr2 of the refrigerant pipe L5 . The refrigerant flow rate Gr2 is calculated based on the opening degree of the expansion valve 40 , the pressure HP at the point b, the pressure LP at the point c, and the temperature detected by the temperature sensor 93 .

[0048] In step S114, the control unit 90 determines whether the refrigerant pressure LP detected by the pressure sensor 92 exceeds a predetermined pressure, and if so, the process proceeds to step S115, and if not, the process proceeds to step S116. The predetermined pressure is a pressure that is higher than the aforementioned threshold pressure and is preset as a pressure suitable for hot gas heating operation.

[0049] In step S115, the control unit 90 increases the opening of the expansion valve 50 so that (ha-hc)×Gr1>(hc-hb)×Gr2. As a result, the ratio of the gas refrigerant in the inflowing refrigerant including the refrigerant expanded by the expansion valve 40 and the refrigerant expanded by the expansion valve 50 flowing into the accumulator 30 can be made larger than the ratio of the gas refrigerant in the outflowing refrigerant flowing out of the accumulator 30.

[0050] exist Figure 6 By increasing the opening of the expansion valve 50, point c corresponding to the outlet side of the accumulator 30 (the suction side of the compressor 10) can be brought closer to point e than point d. Point d corresponds to the downstream side of the expansion valve 40, and point e corresponds to the downstream side of the expansion valve 50.

[0051] Furthermore, the liquid refrigerant stored in the accumulator 30 is reduced by making the ratio of the gas refrigerant in the refrigerant flowing into the accumulator 30 greater than the ratio of the gas refrigerant in the refrigerant flowing out of the accumulator 30. As a result, the pressure of the refrigerant flowing into the compressor 10 increases as the refrigerant flowing through the refrigeration cycle increases, thereby suppressing a reduction in the power of the compressor 10.

[0052] In step S116, the control unit 90 reduces the opening of the expansion valve 50 so that (ha-hc)×Gr1<(hc-hb)×Gr2. As a result, the ratio of liquid refrigerant in the refrigerant flowing into the accumulator 30, including the refrigerant expanded by the expansion valve 40 and the refrigerant expanded by the expansion valve 50, can be made greater than the ratio of liquid refrigerant in the refrigerant flowing out of the accumulator 30. Figure 6 In FIG. 5 , by reducing the opening degree of the expansion valve 50 , the point c corresponding to the outlet side of the accumulator 30 (the suction side of the compressor 10 ) can be brought closer to the point d than the point e.

[0053] Furthermore, by making the ratio of liquid refrigerant in the refrigerant flowing into the accumulator 30 greater than the ratio of liquid refrigerant in the refrigerant flowing out of the accumulator 30, the liquid refrigerant stored in the accumulator 30 increases and the ratio of liquid refrigerant contained in the refrigerant flowing out of the accumulator 30 decreases. As a result, the pressure of the refrigerant flowing into the compressor 10 decreases as the refrigerant circulating in the refrigeration cycle decreases, thereby suppressing an increase in the torque of the compressor 10.

[0054] In step S117, the control unit 90 determines whether an instruction to terminate the hot gas heating operation has been input, and if so, the process of this flowchart is terminated. If not, the process after step S110 is executed again.

[0055] In the hot air heating operation described above, when the power of the compressor 10 is reduced, the control unit 90 controls the opening (first opening) of the expansion valve 40 and the opening (second opening) of the expansion valve 50 so that the ratio of the liquid refrigerant in the inflow refrigerant flowing into the accumulator 30 does not change. And, when the power of the compressor 10 is increased, the control unit 90 controls the opening (first opening) of the expansion valve 40 and the opening (second opening) of the expansion valve 50 so that the ratio of the liquid refrigerant in the inflow refrigerant flowing into the accumulator 30 does not change.

[0056] <Dehumidification and heating operation> refer to Figure 7 Next, the operation of the vehicle air conditioning device 100 according to the present embodiment during the dehumidification and heating operation will be described. Figure 7 1 is a refrigerant circuit diagram showing the flow of the refrigerant during the dehumidification and heating operation of the vehicle air conditioner 100 .

[0057] Figure 7 The arrows shown indicate the flow direction of the refrigerant. Figure 7 As shown, during the dehumidification and heating operation, the refrigerant circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the outdoor heat exchanger 80, the cabin heat exchanger 85, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L3, L4, L5, L10, and L7 form a circulation flow path for circulating the refrigerant.

[0058] During the dehumidification and heating operation, the outdoor heat exchanger 80 operates as an evaporator and evaporates the refrigerant to cool the outside air. During the dehumidification and heating operation, the control unit 90 opens the on-off valve 64 and closes the on-off valves 61, 62, 63, and 65. The control unit 90 drives the cabin blower 86 to guide the air dehumidified by the cabin heat exchanger 85 to the heating unit 20, thereby dehumidifying the moisture contained in the air and heating and blowing the air through the heating unit 20.

[0059] <Cooling Operation> refer to Figure 8 , the operation of the vehicle air conditioning device 100 according to the present embodiment during cooling operation will be described. Figure 8 2 is a refrigerant circuit diagram showing the flow of the refrigerant during the cooling operation of the vehicle air conditioning apparatus 100 .

[0060] Figure 8 The arrows shown indicate the flow direction of the refrigerant. Figure 8 As shown, during cooling operation, the refrigerant circulates in the order of the compressor 10, the outdoor heat exchanger 80, the cabin heat exchanger 85, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L11, L5, L10, and L7 form a circulation flow path for circulating the refrigerant.

[0061] During cooling operation, the outdoor heat exchanger 80 operates as a condenser and condenses the refrigerant to heat the outside air. During cooling operation, the control unit 90 opens the on-off valves 63 and 64 and closes the on-off valves 61, 62, and 65. The control unit 90 can drive the cabin blower 86 to blow the air cooled by the outdoor heat exchanger 80 into the vehicle interior.

[0062] The functions and effects achieved by the vehicle air conditioning device 100 according to the present embodiment described above will be described. According to the vehicle air conditioning device 100 of the present embodiment, a part of the high-temperature and high-pressure refrigerant ejected from the compressor 10 is supplied to the heating unit 20, and the air (heating object) is heated by the heating unit 20. The refrigerant that has passed through the heating unit 20 is expanded by the expansion valve 40, and is guided to the accumulator 30 through the refrigerant pipes L5, L8, L9, and L7. In addition, another part of the high-temperature and high-pressure refrigerant ejected from the compressor 10 is guided to the refrigerant pipe L6 (bypass flow path), and is expanded by the expansion valve 50. The refrigerant expanded by the expansion valve 50 merges with the refrigerant flowing in the refrigerant pipe L7, and is guided to the accumulator 30.

[0063] According to the vehicle air conditioning device 100 of the present embodiment, the opening degree of the expansion valve 40 and the opening degree of the expansion valve 50 are controlled in such a manner that, when the pressure of the refrigerant sucked into the compressor 10 is lower than a predetermined pressure, the ratio of the gas refrigerant in the inflow refrigerant flowing into the accumulator 30 is made greater than the ratio of the gas refrigerant in the outflow refrigerant flowing out of the accumulator 30. Therefore, the liquid refrigerant stored in the accumulator 30 is reduced. As a result, the pressure of the refrigerant flowing into the compressor 10 increases as the refrigerant flowing through the circulation flow path (refrigerant piping L5, L8, L9, L7) and the bypass flow path (refrigerant piping L6) increases, thereby suppressing the reduction in the power of the compressor 10.

[0064] Furthermore, according to the vehicle air conditioning device 100 of the present embodiment, the opening degree of the expansion valve 40 and the opening degree of the expansion valve 50 are controlled in such a manner that when the pressure of the refrigerant sucked into the compressor 10 is higher than the predetermined pressure, the ratio of the liquid refrigerant in the inflow refrigerant flowing into the accumulator 30 is made greater than the ratio of the liquid refrigerant in the outflow refrigerant flowing out of the accumulator 30. Therefore, the liquid refrigerant stored in the accumulator 30 increases. As a result, the pressure of the refrigerant flowing into the compressor 10 decreases as the refrigerant flowing through the circulation flow path (refrigerant piping L5, L8, L9, L7) and the bypass flow path (refrigerant piping L6) decreases, thereby suppressing an increase in the torque of the compressor 10.

[0065] According to the vehicle air conditioning device 100 of this embodiment, in the hot air heating operation for heating the air using the power of the compressor 10, the first operation mode is set to guide the refrigerant ejected from the compressor 10 to the bypass flow path instead of the circulation flow path before the pressure of the refrigerant sucked by the compressor 10 reaches the threshold pressure, so that the pressure of the refrigerant can quickly reach the threshold pressure. In addition, the second operation mode is set in response to the pressure of the refrigerant sucked by the compressor 10 exceeding the threshold pressure, so that the heating unit 20 can appropriately heat the air.

[0066] According to the vehicle air conditioning device 100 of the present embodiment, when the power of the compressor 10 is reduced or increased, it is possible to appropriately suppress the pressure of the refrigerant sucked into the compressor from fluctuating due to the reduction in the power of the compressor.

[0067] According to the vehicle air conditioning device 100 of the present embodiment, when the on-off valve 64 and the on-off valve 65 are in a closed state and the refrigerant circulates in the circulation flow path, a part of the refrigerant sealed in the refrigerant flow path is retained in another refrigerant flow path different from the circulation flow path including the downstream side of the on-off valve 64 of the refrigerant piping L5 and the refrigerant piping L9. Furthermore, even if the on-off valve 64 and the on-off valve 65 are in a closed state, a part of the refrigerant circulating in the circulation flow path flows into the downstream side of the on-off valve 64 of the refrigerant piping L5 and the refrigerant piping L9, thereby reducing the refrigerant circulating in the circulation flow path.

[0068] According to the vehicle air conditioning device 100 of the present embodiment, the amount of refrigerant sealed in the refrigerant flow path including the circulation flow path, the bypass flow path, the first flow path (downstream side of the on-off valve 64 of the refrigerant piping L5), and the second flow path (refrigerant piping L9) is set so that when the on-off valve 64 and the on-off valve 65 are in a closed state and the refrigerant circulates in the circulation flow path, the heating unit 20 can heat the air. Therefore, when the on-off valve 64 and the on-off valve 65 are in a closed state and the refrigerant circulates in the circulation flow path, the heating unit 20 can appropriately heat the air.

[0069] According to the vehicle air conditioning apparatus 100 of the present embodiment, the refrigerant flowing into the accumulator 30 is heated by the refrigerant heater 91 , thereby making it possible to increase the specific enthalpy of the refrigerant flowing into the accumulator 30 .

[0070] According to vehicle air conditioner 100 of the present embodiment, cabin blower 86 is driven to guide air dehumidified by cabin heat exchanger 85 to heating unit 20 , so that moisture contained in the air can be dehumidified and the air can be heated and blown by heating unit 20 .

[0071] According to the vehicle air conditioner 100 of this embodiment, the opening of the expansion valve 40 is adjusted so that the refrigerant passing through the heating unit 20 becomes liquid refrigerant. Therefore, it is possible to appropriately prevent the gas-liquid two-phase refrigerant from flowing into the expansion valve 40 and increasing the refrigerant flow noise.

[0072] The air-conditioning apparatus and the control method of the air-conditioning apparatus described in each of the above-described embodiments can be understood, for example, as follows. The air conditioning device (100) according to the first aspect of the present invention comprises: a compressor (10) for compressing a refrigerant; a heating unit (20) for heating a heating object by using the refrigerant ejected from the compressor; an accumulator (30) for separating a liquid component from the refrigerant sucked into the compressor; a circulation flow path (L5, L8, L9, L7) for guiding the refrigerant that has passed through the heating unit to the accumulator; a bypass flow path (L6) for guiding the refrigerant ejected from the compressor without passing through the heating unit to the accumulator; a first expansion mechanism (40) arranged in the circulation flow path for expanding the refrigerant ejected from the heating unit; and a second expansion mechanism (50) arranged in the bypass flow path for expanding the refrigerant ejected from the compressor. expansion of the refrigerant; and a control unit (90) for controlling a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism, the control unit controlling the first opening degree and the second opening degree in the following manner: when the pressure of the refrigerant sucked into the compressor is lower than a specified pressure, the ratio of gas refrigerant in the refrigerant flowing into the accumulator, which includes the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism, is made greater than the ratio of gas refrigerant in the refrigerant flowing out of the accumulator; and when the pressure of the refrigerant sucked into the compressor is higher than the specified pressure, the ratio of liquid refrigerant in the refrigerant flowing into the accumulator is made greater than the ratio of liquid refrigerant in the refrigerant flowing out of the accumulator.

[0073] According to the air conditioning device involved in the first embodiment of the present invention, a part of the high-temperature and high-pressure refrigerant ejected from the compressor is supplied to the heating unit, and the heating object is heated by the heating unit. The refrigerant that has passed through the heating unit is expanded by the first expansion mechanism and guided to the accumulator through the circulation flow path. In addition, another part of the high-temperature and high-pressure refrigerant ejected from the compressor is guided to the bypass flow path and expanded by the second expansion mechanism. The refrigerant expanded by the second expansion mechanism merges with the refrigerant circulating in the circulation flow path and is guided to the accumulator.

[0074] According to the air conditioning device involved in the first aspect of the present invention, the first opening degree and the second opening degree are controlled in the following manner: when the pressure of the refrigerant sucked by the compressor is lower than the specified pressure, the proportion of the gas refrigerant in the refrigerant flowing into the accumulator is made greater than the proportion of the gas refrigerant in the refrigerant flowing out of the accumulator. Therefore, the liquid refrigerant stored in the accumulator is reduced. As a result, the pressure of the refrigerant flowing into the compressor increases with the increase of the refrigerant flowing in the circulation flow path and the bypass flow path, thereby suppressing the reduction of the power of the compressor.

[0075] Furthermore, according to the air conditioning device involved in the first aspect of the present invention, the first opening degree and the second opening degree are controlled in the following manner: when the pressure of the refrigerant sucked by the compressor is higher than the specified pressure, the proportion of liquid refrigerant in the inflow refrigerant flowing into the accumulator is made greater than the proportion of liquid refrigerant in the outflow refrigerant flowing out of the accumulator. Therefore, the liquid refrigerant stored in the accumulator increases. As a result, the pressure of the refrigerant flowing into the compressor decreases as the refrigerant circulating in the circulation flow path and the bypass flow path decreases, thereby suppressing the increase in the torque of the compressor.

[0076] The air conditioning device according to the second aspect of the present invention further comprises the following structure in the first aspect. That is, the control unit comprises a switching unit (61), the switching unit switches between a first operation mode and a second operation mode, the first operation mode directing the refrigerant ejected from the compressor to the bypass flow path instead of to the circulation flow path, and the second operation mode directing the refrigerant ejected from the compressor to both the circulation flow path and the bypass flow path, the control unit controls the switching unit in such a manner that the first operation mode is switched to the second operation mode when the pressure of the refrigerant sucked into the compressor exceeds a threshold pressure.

[0077] According to the air conditioner involved in the second aspect of the present invention, in the hot air heating operation for heating the heating object by using the power of the compressor, the first operation mode is set to guide the refrigerant ejected from the compressor to the bypass flow path instead of the circulation flow path before the pressure of the refrigerant sucked by the compressor reaches the threshold pressure, so that the pressure of the refrigerant can quickly reach the threshold pressure. In addition, the second operation mode is set in response to the pressure of the refrigerant sucked by the compressor exceeding the threshold pressure, so that the heating object can be appropriately heated by the heating unit.

[0078] The air conditioner according to the third aspect of the present invention further comprises the following structure in the first aspect or the second aspect: That is, the control unit controls the first opening degree and the second opening degree in such a manner that the ratio of the liquid refrigerant in the inflow refrigerant remains unchanged when the power of the compressor is reduced. According to the air conditioning apparatus according to the third aspect of the present invention, when the power of the compressor is reduced, it is possible to appropriately suppress the pressure of the refrigerant sucked into the compressor from fluctuating due to the reduction in the power of the compressor.

[0079] The air conditioner according to the fourth aspect of the present invention further comprises the following structure in the first aspect or the second aspect: That is, the control unit controls the first opening degree and the second opening degree in such a manner that the ratio of the liquid refrigerant in the inflow refrigerant remains unchanged when the power of the compressor is increased. According to the air conditioning apparatus according to the fourth aspect of the present invention, when the power of the compressor is increased, it is possible to appropriately suppress the pressure of the refrigerant sucked into the compressor from fluctuating due to the increase in the power of the compressor.

[0080] The air conditioner according to the fifth aspect of the present invention further comprises the following structure in the first aspect or the second aspect: a heat exchanger (80) for performing heat exchange between outside air and the refrigerant; a first flow path (L5) for guiding the refrigerant having passed through the heating unit to the heat exchanger; a second flow path (L9) for guiding the refrigerant having passed through the heat exchanger to the accumulator; a first opening and closing valve (64) arranged in the first flow path; and a second opening and closing valve (65) arranged in the second flow path, the amount of the refrigerant sealed in the refrigerant flow path including the circulation flow path, the bypass flow path, the first flow path, and the second flow path being set so that when the first opening and closing valve and the second opening and closing valve are in a closed state and the refrigerant circulates in the circulation flow path, the heating unit can heat the heating object.

[0081] According to the air conditioning device involved in the fifth aspect of the present invention, when the first opening and closing valve and the second opening and closing valve are closed and the refrigerant circulates in the circulation flow path, a part of the refrigerant sealed in the refrigerant flow path is retained in another refrigerant flow path different from the circulation flow path including the first flow path and the second flow path. Furthermore, even if the first opening and closing valve and the second opening and closing valve are closed, a part of the refrigerant circulating in the circulation flow path flows into the first flow path and the second flow path, thereby causing a reduction in the refrigerant circulating in the circulation flow path.

[0082] According to the air conditioning device involved in the fifth aspect of the present invention, the amount of refrigerant sealed in the refrigerant flow path including the circulation flow path, the bypass flow path, the first flow path, and the second flow path is set so that when the first opening and closing valve and the second opening and closing valve are in a closed state and the refrigerant circulates in the circulation flow path, the heating object can be heated by the heating unit. Therefore, when the first opening and closing valve and the second opening and closing valve are in a closed state and the refrigerant circulates in the circulation flow path, the heating object can be appropriately heated by the heating unit.

[0083] The air conditioner according to the sixth aspect of the present invention, in the first aspect or the second aspect, further comprises a refrigerant heater (95) for heating the refrigerant flowing into the accumulator. According to the air conditioning apparatus according to the sixth aspect of the present invention, the refrigerant flowing into the accumulator is heated by the refrigerant heater, thereby making it possible to increase the pressure of the refrigerant flowing into the accumulator.

[0084] The air conditioner according to the seventh aspect of the present invention, in the first aspect or the second aspect, further comprises the following structure: that is, comprising: a heat exchanger (80) for performing heat exchange between outside air and the refrigerant; an evaporator (85) for evaporating the refrigerant having passed through the heat exchanger; a blower (86) for guiding the air dehumidified by the evaporator to the heating unit; a first flow path (L5) for guiding the refrigerant having passed through the heating unit to the heat exchanger; and a second flow path (L9) for guiding the refrigerant having passed through the heat exchanger via the evaporator to the accumulator. According to the air conditioning apparatus of the seventh aspect of the present invention, the air dehumidified by the evaporator is guided to the heating unit by driving the blower, so that moisture contained in the air can be dehumidified and the air can be heated and blown by the heating unit.

[0085] The air conditioning apparatus according to the eighth aspect of the present invention, in the first aspect or the second aspect, further comprises a configuration in which the control unit controls the opening degree of the first expansion mechanism so that the refrigerant having passed through the heating unit becomes liquid refrigerant. According to the air conditioning device involved in the 8th aspect of the present invention, the opening degree of the first expansion mechanism is adjusted in such a way that the refrigerant passing through the heating unit becomes liquid refrigerant, thereby appropriately preventing the gas-liquid two-phase refrigerant from flowing into the first expansion mechanism and increasing the refrigerant flow sound.

[0086] In a control method for an air-conditioning device according to a ninth aspect of the present invention, the air-conditioning device comprises: a compressor for compressing a refrigerant; a heating unit for heating a heating object by means of the refrigerant ejected from the compressor; an accumulator for separating a liquid component from the refrigerant sucked into the compressor; a circulation flow path for guiding the refrigerant having passed through the heating unit to the accumulator; a bypass flow path for guiding the refrigerant ejected from the compressor without passing through the heating unit to the accumulator; a first expansion mechanism for expanding the refrigerant ejected from the heating unit; and a second expansion mechanism for expanding the refrigerant ejected from the compressor. The control method for the air-conditioning device comprises: a first control mechanism for A control step of controlling the first opening degree of the first expansion mechanism and the second opening degree of the second expansion mechanism in such a manner that, when the pressure of the refrigerant sucked by the compressor is lower than a specified pressure, the ratio of the gas refrigerant in the inflowing refrigerant including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism and flowing into the accumulator is greater than the ratio of the gas refrigerant in the outflowing refrigerant flowing out of the accumulator; and a second control step of controlling the first opening degree and the second opening degree in such a manner that, when the pressure of the refrigerant sucked by the compressor is higher than the specified pressure, the ratio of the liquid refrigerant in the inflowing refrigerant is greater than the ratio of the liquid refrigerant in the outflowing refrigerant flowing out of the accumulator.

[0087] According to the control method of the air conditioner according to the ninth aspect of the present invention, a part of the high-temperature and high-pressure refrigerant ejected from the compressor is supplied to the heating unit, and the heating object is heated by the heating unit. The refrigerant that has passed through the heating unit is expanded by the first expansion mechanism and guided to the accumulator through the circulation flow path. In addition, another part of the high-temperature and high-pressure refrigerant ejected from the compressor is guided to the bypass flow path and expanded by the second expansion mechanism. The refrigerant expanded by the second expansion mechanism merges with the refrigerant circulating in the circulation flow path and is guided to the accumulator.

[0088] According to the control method of the air conditioner involved in the 9th aspect of the present invention, the first opening degree and the second opening degree are controlled in the following manner: when the pressure of the refrigerant sucked by the compressor is lower than the specified pressure, the proportion of the gas refrigerant in the refrigerant flowing into the accumulator is made greater than the proportion of the gas refrigerant in the refrigerant flowing out of the accumulator. Therefore, the liquid refrigerant stored in the accumulator decreases and the proportion of the liquid refrigerant contained in the refrigerant flowing out of the accumulator increases. As a result, the pressure of the refrigerant flowing into the compressor increases with the increase of the refrigerant circulating in the circulation flow path and the bypass flow path, thereby suppressing the reduction of the power of the compressor.

[0089] Furthermore, according to the control method of the air conditioning device involved in the ninth aspect of the present invention, the first opening and the second opening are controlled in the following manner: when the pressure of the refrigerant sucked by the compressor is higher than the specified pressure, the proportion of liquid refrigerant in the inflow refrigerant flowing into the accumulator is made greater than the proportion of liquid refrigerant in the outflow refrigerant flowing out of the accumulator. Therefore, the liquid refrigerant stored in the accumulator increases and the proportion of liquid refrigerant contained in the refrigerant flowing out of the accumulator decreases. As a result, the pressure of the refrigerant flowing into the compressor decreases as the refrigerant circulating in the circulation flow path and the bypass flow path decreases, thereby suppressing the increase in the torque of the compressor. Explanation of symbols

[0090] 10- compressor, 20- heating unit, 30- accumulator, 40- expansion valve (first expansion mechanism), 50- expansion valve (second expansion mechanism), 61, 62, 63- opening and closing valves, 64- opening and closing valves (first opening and closing valves), 65- opening and closing valves (second opening and closing valves), 70- expansion valve, 80- outdoor heat exchanger, 81- outdoor fan, 85- cabin heat exchanger (evaporator), 86- cabin blower, 90- control unit, 91- refrigerant heater, 92, 96- pressure sensor, 93, 94, 95- temperature sensor, 100- vehicle air conditioning device, Gr1, Gr2- refrigerant flow rate, L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11- refrigerant piping.

Claims

1. An air conditioning device, comprising: compressor, which compresses the refrigerant; a heating unit that heats a heating object using the refrigerant ejected from the compressor; an accumulator for separating a liquid component from the refrigerant sucked by the compressor; a circulation flow path for guiding the refrigerant having passed through the heating unit to the accumulator; a bypass flow path for guiding the refrigerant discharged from the compressor without passing through the heating unit to the accumulator; a first expansion mechanism disposed in the circulation flow path and expanding the refrigerant flowing out of the heating unit; a second expansion mechanism disposed in the bypass flow path and expanding the refrigerant discharged from the compressor; and a control unit that controls a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism, The control unit controls the first opening and the second opening in the following manner: When the pressure of the refrigerant sucked into the compressor is lower than a predetermined pressure, a ratio of gas refrigerant in the refrigerant flowing into the accumulator, including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism, is made greater than a ratio of gas refrigerant in the refrigerant flowing out of the accumulator; and When the pressure of the refrigerant sucked into the compressor is higher than the predetermined pressure, the ratio of the liquid refrigerant in the inflow refrigerant is made larger than the ratio of the liquid refrigerant in the outflow refrigerant flowing out of the accumulator.

2. The air conditioning device according to claim 1, comprising: a switching unit for switching between a first operation mode and a second operation mode, wherein the first operation mode guides the refrigerant discharged from the compressor to the bypass flow path instead of to the circulation flow path, and the second operation mode guides the refrigerant discharged from the compressor to both the circulation flow path and the bypass flow path, The control unit controls the switching unit so as to switch the first operation mode to the second operation mode in response to the pressure of the refrigerant sucked into the compressor exceeding a threshold pressure.

3. The air conditioning device according to claim 1 or 2, wherein: The control unit controls the first opening degree and the second opening degree so that the ratio of the liquid refrigerant in the inflow refrigerant does not change when the power of the compressor is reduced.

4. The air conditioning device according to claim 1 or 2, wherein: The control unit controls the first opening degree and the second opening degree so that the ratio of the liquid refrigerant in the inflow refrigerant does not change when the power of the compressor is increased.

5. The air conditioning device according to claim 1 or 2, comprising: a heat exchanger for performing heat exchange between external air and the refrigerant; a first flow path for guiding the refrigerant having passed through the heating unit to the heat exchanger; a second flow path for guiding the refrigerant having passed through the heat exchanger to the accumulator; a first on-off valve disposed in the first flow path; and a second on-off valve, arranged in the second flow path, The amount of the refrigerant sealed in the refrigerant flow path including the circulation flow path, the bypass flow path, the first flow path and the second flow path is set so that when the first on-off valve and the second on-off valve are in a closed state and the refrigerant circulates in the circulation flow path, the heating unit can heat the heating object. 6 . The air conditioning apparatus according to claim 1 , further comprising a refrigerant heater configured to heat the refrigerant flowing into the accumulator.

7. The air conditioning device according to claim 1 or 2, comprising: a heat exchanger for performing heat exchange between external air and the refrigerant; an evaporator for evaporating the refrigerant having passed through the heat exchanger; a blower for guiding the air dehumidified by the evaporator to the heating part; a first flow path for guiding the refrigerant having passed through the heating unit to the heat exchanger; and The second flow path guides the refrigerant having passed through the heat exchanger via the evaporator to the accumulator.

8. The air conditioning device according to claim 1 or 2, wherein: The control unit controls the opening degree of the first expansion mechanism so that the refrigerant having passed through the heating unit becomes liquid refrigerant.

9. A method for controlling an air conditioning device, The air conditioning device comprises: compressor, which compresses the refrigerant; a heating unit that heats a heating object using the refrigerant ejected from the compressor; an accumulator for separating a liquid component from the refrigerant sucked by the compressor; a circulation flow path for guiding the refrigerant having passed through the heating unit to the accumulator; a bypass flow path for guiding the refrigerant discharged from the compressor without passing through the heating unit to the accumulator; a first expansion mechanism disposed in the circulation flow path and expanding the refrigerant flowing out of the heating unit; and The second expansion mechanism is disposed in the bypass flow path and expands the refrigerant discharged from the compressor. The control method of the air conditioning device comprises: a first control step of controlling a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism so that, when the pressure of the refrigerant sucked into the compressor is lower than a predetermined pressure, a ratio of gas refrigerant in the refrigerant flowing into the accumulator including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism is greater than a ratio of gas refrigerant in the refrigerant flowing out of the accumulator; and The second control process controls the first opening and the second opening in the following manner, that is, when the pressure of the refrigerant sucked into the compressor is higher than the specified pressure, the proportion of the liquid refrigerant in the inflowing refrigerant is greater than the proportion of the liquid refrigerant in the outflowing refrigerant flowing out of the accumulator.

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