Vehicle air conditioning system

Abstract

The present invention provides a vehicle air conditioning system that can suppress fluctuations in the discharge temperature and thereby prevent deterioration of comfort. [Solution] During the operating mode in which the radiator 61, acting as an outside air heat exchange unit, exchanges heat with the outside air, the pressure and / or temperature of the refrigerant drawn in by the compressor 11 are controlled to reach a target value. Therefore, it becomes possible to keep the pressure and / or temperature of the refrigerant drawn in by the compressor 11 constant when disturbances (fluctuations in heat load) occur, thereby suppressing fluctuations in the refrigeration cycle. This makes it possible to suppress fluctuations in the discharge temperature, thereby suppressing deterioration of occupant comfort.

Description

Technical Field

[0001] The present invention relates to a vehicle air conditioner.

Background Art

[0002] As an air conditioner for an electric vehicle (EV: Electric Vehicle) that does not have a combustion heat source such as an engine or a vehicle with a small amount of heat from a combustion heat source, for example, a vehicle air conditioner capable of performing a hot gas heating operation in which a part of the refrigerant discharged from the compressor flows through a bypass path and the remaining refrigerant flows through a condenser is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a vehicle air conditioner capable of suppressing fluctuations in the blowing temperature and suppressing deterioration of comfort.

Means for Solving the Problems

[0005] According to one aspect of the present invention, a vehicle air conditioning system includes a compressor, a condenser, a first pressure reducing device, a second pressure reducing device, and a bypass path through which a portion of the refrigerant discharged by the compressor bypasses the condenser and flows to the upstream side of the compressor, wherein the second pressure reducing device is located on the bypass path, and the system provides a refrigerant circuit that, when the refrigerant circuit operates, exchanges heat in a heat source side heat exchange section including an outside air heat exchange section that exchanges heat with outside air, and exchanges heat in a utilization side heat exchange section to air condition the interior of a vehicle, wherein, in an operating mode in which the outside air heat exchange section exchanges heat with outside air, the state of the refrigerant inhaled by the compressor and / or the refrigerant discharged by the compressor is controlled so that at least the pressure and temperature of the refrigerant inhaled by the compressor and the pressure of the refrigerant discharged by the compressor reach target values. [Effects of the Invention]

[0006] According to the present invention, it is possible to suppress fluctuations in the discharge temperature and provide a vehicle air conditioning system that can suppress deterioration of comfort. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is an explanatory diagram showing an example of a circuit diagram during heating operation in a refrigerant circuit equipped with an accumulator. [Figure 2] Figure 2 is an explanatory diagram showing an example of a circuit diagram during cooling operation in a refrigerant circuit equipped with an accumulator. [Figure 3] Figure 3 is an explanatory diagram showing an example of a circuit diagram during heating operation in a refrigerant circuit equipped with a liquid receiver. [Figure 4] Figure 4 is an explanatory diagram showing an example of a circuit diagram during cooling operation in a refrigerant circuit equipped with a liquid receiver. [Figure 5] Figure 5 is an explanatory diagram showing a modified example of a refrigerant circuit equipped with an accumulator. [Modes for carrying out the invention]

[0008] [System Configuration] <System Overview> Figure 1 is an explanatory diagram illustrating a schematic configuration example of a vehicle air conditioning system 1 according to this embodiment. The vehicle air conditioning system 1 is mounted on a vehicle. The vehicle is preferably a vehicle equipped with a battery for driving. The vehicle may be, for example, an electric vehicle (BEV: Battery Electric Vehicle), a hybrid vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle), or a fuel cell vehicle (FCEV: Fuel Cell Electric Vehicle).

[0009] The vehicle air conditioning system 1 includes a refrigerant circuit 10 through which a refrigerant circulates. The refrigerant may be, but is not limited to, hydrofluoroolefins.

[0010] Furthermore, the vehicle air conditioning system 1 includes a high-temperature side heat transfer medium circuit 20, a low-temperature side heat transfer medium circuit 30, a battery temperature control circuit 40, a motor temperature control circuit 50, and an outdoor heat exchange circuit 60, all configured to circulate a fluid heat transfer medium such as coolant.

[0011] Of these circuits, the low-temperature heat transfer fluid circuit 30, the battery temperature control circuit 40, the motor temperature control circuit 50, and the outdoor heat exchange circuit 60 are connected to a flow path switching device 71 such as an eight-way valve. The flow path switching device 71 can connect these flow paths to each other to form a circulation path in which these circuits work together to circulate the heat transfer fluid, or it can disconnect one or more circuits from other circuits to make them independent.

[0012] Furthermore, the high-temperature heat transfer fluid circuit 20 and the outdoor heat exchange circuit 60 are connected to a flow path switching device such as a four-way valve V20 that connects or disconnects their respective flow paths. This four-way valve V20 can either form a circulation path in which the high-temperature heat transfer fluid circuit 20 and the outdoor heat exchange circuit 60 work together to circulate the heat transfer fluid, or it can disconnect these circuits from each other.

[0013] Furthermore, the vehicle air conditioning system 1 includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 100 as an air conditioning unit.

[0014] Furthermore, the vehicle air conditioning system 1 is equipped with a control device 200. The control device 200 is an ECU (Electronic Control Unit) for executing various controls of the vehicle air conditioning system 1. The control device 200 generates control commands based on sensor values ​​obtained from various sensors included in the vehicle air conditioning system 1, user operations, etc., and outputs the generated control commands to each part of the vehicle air conditioning system 1. In this way, the operation of the vehicle air conditioning system 1 is controlled by the control device 200.

[0015] <Refrigerant Circuit> The refrigerant circuit 10 includes a compressor 11 that compresses gaseous refrigerant to high temperature and pressure before discharge, a high-temperature side heat exchanger 12 that condenses the compressed gaseous refrigerant to release heat, pressure reducing devices 13a, 13b, 13c such as expansion valves that expand liquid refrigerant to low pressure, and a low-temperature side heat exchanger 14 that evaporates the low-temperature, low-pressure liquid refrigerant to absorb heat. The high-temperature side heat exchanger 12 functions as a condenser that heats the heat transfer medium. The refrigerant circuit 10 is configured to function as a heat pump that circulates the refrigerant and repeatedly compresses, condenses, expands, and evaporates it.

[0016] In the high-temperature heat exchanger 12, the refrigerant exchanges heat with the heat transfer medium circulating in the high-temperature heat transfer medium circuit 20. In the low-temperature heat exchanger 14, the refrigerant exchanges heat with the heat transfer medium circulating in the low-temperature heat transfer medium circuit 30.

[0017] In the example shown in the figure, the high-temperature side heat exchanger 12 includes a refrigerant passage 12a through which the refrigerant circulating in the refrigerant circuit 10 passes, and a heat medium passage 12b through which the heat medium circulating in the high-temperature side heat medium circuit 20 passes. The low-temperature side heat exchanger 14 includes a refrigerant passage 14a through which the refrigerant circulating in the refrigerant circuit 10 passes, and a heat medium passage 14b through which the heat medium circulating in the low-temperature side heat medium circuit 30 passes.

[0018] The discharge side 11a of the compressor 11 is connected to the inlet of the refrigerant passage 12a of the high-temperature side heat exchanger 12 via the refrigerant flow path 10a, the branch point a1, and the refrigerant flow path 10b downstream thereof. The outlet of the refrigerant passage 12a of the high-temperature side heat exchanger 12 is connected to the inlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 via the refrigerant flow path 10c. A decompression device 13a as a first decompression device is installed on the path of the refrigerant flow path 10c.

[0019] Also, the outlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 is connected to the suction side 11b of the compressor 11 via the refrigerant flow path 10d, the confluence point b1, the refrigerant flow path 10e, the confluence point b2, and the refrigerant flow path 10f downstream thereof. An accumulator 15 is installed on the path of the refrigerant flow path 10e.

[0020] Also, the discharge side 11a of the compressor 11 is connected to the suction side 11b of the compressor 11 via the refrigerant flow path 10a, the branch point a1, the refrigerant flow path 10g, the confluence point b1, the refrigerant flow path 10e, the confluence point b2, and the refrigerant flow path 10f downstream thereof. A decompression device 13b as a second decompression device is installed on the path of the refrigerant flow path 10g.

[0021] Also, the discharge side 11a of the compressor 11 is connected to the suction side 11b of the compressor 11 via the refrigerant flow path 10a, the branch point a1, the refrigerant flow path 10h, the confluence point b2, and the refrigerant flow path 10f downstream thereof. A decompression device 13c as a second decompression device is installed on the path of the refrigerant flow path 10h.

[0022] As described above, the refrigerant flow paths 10a, 10g, 10e, and 10f function as a bypass path through which a part of the refrigerant discharged from the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11. Also, the refrigerant flow paths 10a, 10h, and 10f function as a bypass path through which a part of the refrigerant discharged from the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11.

[0023] 〈High-temperature side heat medium circuit〉 The high-temperature side heat transfer medium circuit 20 includes a heat transfer medium passage 12b of the high-temperature side heat exchanger 12 and a heater core 21 that heats the air supplied to the vehicle interior. The high-temperature side heat transfer medium circuit 20 is a circuit through which a heat transfer medium, heated by receiving heat from the refrigerant circuit 10 via the high-temperature side heat exchanger 12, circulates. The high-temperature side heat transfer medium circuit 20 can be used to operate the heater core 21 and heat the vehicle interior.

[0024] The inlet side 21a of the heater core 21 is connected to the outlet of the heat transfer medium passage 12b of the high-temperature side heat exchanger 12 by a heat transfer medium passage 20a. The outlet side 21b of the heater core 21 is connected to the four-way valve V20 by a heat transfer medium passage 20b. The inlet of the heat transfer medium passage 12b of the high-temperature side heat exchanger 12 is connected to the four-way valve V20 by a heat transfer medium passage 20c.

[0025] A circulation pump P20 for circulating the heat transfer medium is installed along the path of this heat transfer medium flow path 20c. The heat transfer medium is pushed out by the circulation pump P20 and circulates through the high-temperature side heat transfer medium circuit 20. The heat transfer medium, which has been heated by receiving heat from the refrigerant circuit 10 as it passes through the heat transfer medium passage 12b of the high-temperature side heat exchanger 12, is supplied to the heater core 21 from the inlet side 21a and passes through the heater core 21. At this time, the heater core 21 functions as the heat transfer medium releases heat in the heater core 21. After passing through the heater core 21, the heat transfer medium discharged from the outlet side 21b returns to the heat transfer medium passage 12b of the high-temperature side heat exchanger 12.

[0026] <Low temperature side heat medium circuit> The low-temperature side heat transfer medium circuit 30 includes a heat transfer medium passage 14b of the low-temperature side heat exchanger 14 and a cooler core 31 that cools the air supplied to the vehicle interior. The low-temperature side heat transfer medium circuit 30 is a circuit in which the heat transfer medium, cooled by transferring heat to the refrigerant circuit 10 via the low-temperature side heat exchanger 14, circulates. The low-temperature side heat transfer medium circuit 30 can be used to operate the cooler core 31 to cool or dehumidify the vehicle interior.

[0027] The outlet of the heat transfer medium passage 14b of the low-temperature side heat exchanger 14 and the three-way valve V30 are connected by a heat transfer medium passage 30a, and the three-way valve V30 and the inlet side 31a of the cooler core 31 are connected by a heat transfer medium passage 30b. When the three-way valve V30 connects these heat transfer medium passages 30a and 30b, the outlet of the heat transfer medium passage 14b of the low-temperature side heat exchanger 14 and the inlet side 31a of the cooler core 31 are connected.

[0028] The outlet side 31b of the cooler core 31 is connected to the inlet of the heat medium passage 14b of the low-temperature heat exchanger 14 via the heat medium passage 30c, confluence point b3, heat medium passage 30d, confluence point b4, and the downstream heat medium passage 30e. A backflow prevention valve V31 is installed along the path of the heat medium passage 30c to prevent backflow of the heat medium to the cooler core 31. A circulation pump P30 for circulating the heat medium is installed along the path of the heat medium passage 30d.

[0029] The three-way valve V30 and the flow path switching device 71 are connected by a heat transfer fluid flow path 30f. By disconnecting the connection to the cooler core 31 with the three-way valve V30 and connecting the outlet of the heat transfer fluid passage 14b of the low-temperature side heat exchanger 14 to the flow path switching device 71 with heat transfer fluid flow paths 30a and 30e, a bypass flow path is formed that bypasses the cooler core 31.

[0030] The flow path switching device 71 is connected to the outlet of the heat medium passage 14b of the low-temperature side heat exchanger 14 via the heat medium passage 30g, branch point a2, heat medium passage 30h, confluence point b4, and the heat medium passage 30e downstream thereof.

[0031] Furthermore, the flow path switching device 71 is connected to the confluence point b3 via the heat transfer fluid flow path 30g, the branching point a2, and the heat transfer fluid flow path 30i downstream thereof.

[0032] In the low-temperature side heat transfer medium circuit 30, the heat transfer medium is circulated by being pushed by the circulation pump P30. As the heat transfer medium passes through the heat transfer medium passage 14b of the low-temperature side heat exchanger 14, it is cooled by releasing heat to the refrigerant circuit 10. The cooled heat transfer medium can be supplied to the cooler core 31 from the inlet side 31a and pass through the cooler core 31. At this time, the cooler core 31 can function by absorbing heat in the cooler core 31. After passing through the cooler core 31, the heat transfer medium discharged from the outlet side 31b returns to the heat transfer medium passage 14b of the low-temperature side heat exchanger 14. On the other hand, the heat transfer medium that bypasses the cooler core 31 passes through at least one of the battery temperature control circuit 40, motor temperature control circuit 50, and outdoor heat exchange circuit 60, which are connected via the flow path switching device 71, before returning to the heat transfer medium passage 14b of the low-temperature side heat exchanger 14.

[0033] <Battery temperature control circuit> The battery temperature control circuit 40 includes a battery 41 as the device to be temperature controlled. The battery 41 is provided with a battery temperature control unit for controlling the temperature of the battery 41. The battery temperature control circuit 40 can be used to adjust the temperature of the battery 41.

[0034] In this embodiment, the battery 41 is given as an example of the device to be temperature controlled, but the device to be temperature controlled is not limited to the battery 41. For example, the device to be temperature controlled may be the motor 51.

[0035] The inlet side 41a of the battery 41 is connected to the flow path switching device 71 by a heat transfer medium flow path 40a. The outlet side 41b of the battery 41 is connected to the flow path switching device 71 by a heat transfer medium flow path 40b.

[0036] Along the path of the heat transfer medium flow path 40a, a circulation pump P40 and a heat transfer medium heating device 42 are installed in order from the upstream side. Even if the battery temperature control circuit 40 forms a circulation path independent of other circuits, or even if the other circuit with which it cooperates to form a circulation path does not have a circulation pump installed, the heat transfer medium can be circulated by the circulation pump P40, and the temperature of the battery 41 can be adjusted by the circulation of the heat transfer medium.

[0037] <Motor temperature control circuit> The motor temperature control circuit 50 includes a motor 51 as an in-vehicle device. The motor 51 is provided with a motor temperature control unit for controlling the temperature of the motor 51. The motor temperature control circuit 50 can be used to adjust the temperature of the motor 51 by circulating a heat transfer medium. In addition, the vehicle air conditioning system 1 can use the motor 51, which constantly generates heat during driving, as a heat source via the motor temperature control circuit 50.

[0038] In the example shown in the figure, each element of the motor temperature control circuit 50 is connected by heat transfer fluid passages 50a and 50b. The inlet side 51a of the motor 51 is connected to the flow path switching device 71 by the heat transfer fluid passage 50a. The outlet side 51b of the motor 51 is connected to the flow path switching device 71 by the heat transfer fluid passage 50b.

[0039] <Outdoor heat exchange circuit> The outdoor heat exchange circuit 60 includes a radiator 61 as an outside air heat exchange unit. The outdoor heat exchange circuit 60 can be used to circulate a heat transfer medium and exchange heat between the heat transfer medium and the outside air.

[0040] The inlet side 61a of the radiator 61 is connected to the four-way valve V20 by a heat transfer fluid passage 60a. The outlet side 61b of the radiator 61 is connected to the flow path switching device 71 by a heat transfer fluid passage 60b. The flow path switching device 71 and the four-way valve V20 are connected by a heat transfer fluid passage 60c. When the four-way valve V20 connects the heat transfer fluid passages 60a and 60c, the inlet side 61a of the radiator 61 is connected to the flow path switching device 71.

[0041] <HVAC Unit> The heater core 21 of the high-temperature heat transfer medium circuit 20 and the cooler core 31 of the low-temperature heat transfer medium circuit 30 are housed within the case 110 of the HVAC unit 100. The case 110 forms the outer shell of the HVAC unit 100 and also forms an air passage 120 inside.

[0042] Furthermore, the HVAC unit 100 has an intake unit 130. The intake unit 130 switches the air introduced into the case 110 between outside air (outside air introduction) and inside air (inside air circulation) by closing either the outside air intake port for introducing outside air or the inside air intake port for introducing inside air. In addition, the HVAC unit 100 has a blower 140 installed adjacent to the intake unit 130 so that the air introduced into the case 110 is supplied to the air passage 120.

[0043] A cooler core 31 is installed on the upstream side of the airflow passage 120. A heater core passage 121 and a bypass passage 122 are formed in parallel on the downstream side of the airflow passage 120. The heater core 21 is located in the heater core passage 121. Therefore, when air introduced into the case 110 is directed to the heater core passage 121, the air is passed through the cooler core 31 before being passed through the heater core 21. On the other hand, when air introduced into the case 110 is directed to the bypass passage 122, the air is passed through the cooler core 31 before bypassing the heater core 21. The ratio of air passing through the heater core passage 121 to air passing through the bypass passage 122 is adjusted by the air mix damper 150.

[0044] [System operation] The specific operation of the vehicle air conditioning system 1 according to this embodiment will be explained with reference to Figures 1 and 2.

[0045] <Heater operation> Figure 1 shows the circuit state of the vehicle air conditioning system 1 when the outside temperature is such that heating operation is performed.

[0046] As shown in Figure 1, when performing heating operation, the refrigerant circuit 10 is set as follows: the pressure reducing device 13a is opened. This forms refrigerant flow paths 10a, 10b, 10c, 10d, 10e, and 10f so that the refrigerant discharged from the discharge side 11a of the compressor 11 flows into the suction side 11b of the compressor 11 via the high-temperature side heat exchanger 12 and the low-temperature side heat exchanger 14.

[0047] Furthermore, the pressure reducing device 13b is opened. This forms refrigerant flow paths 10a, 10g, 10e, and 10f so that the refrigerant discharged from the discharge side 11a of the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11.

[0048] Furthermore, the pressure reducing device 13c is opened. This forms refrigerant flow paths 10a, 10h, and 10f so that the refrigerant discharged from the discharge side 11a of the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11.

[0049] As a result, a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature heat exchanger 12 and flows into a bypass path that flows upstream of the compressor 11, while the remaining refrigerant that does not flow into the bypass path flows into the high-temperature heat exchanger 12.

[0050] The high-temperature side heat transfer medium circuit 20, through which the heat transfer medium exchanged in the high-temperature side heat exchanger 12 flows, is configured as follows: The four-way valve V20 connects the heat transfer medium flow paths 20b and 20c so that the heat transfer medium heated by heat exchange in the high-temperature side heat exchanger 12 circulates through the high-temperature side heat transfer medium circuit 20, which is disconnected from the outdoor heat exchange circuit 60, and flows through the heater core 21.

[0051] As a result, the heat transfer medium that absorbed heat in the high-temperature heat exchanger 12 exchanges heat with the heater core 21, thereby heating the vehicle interior. At this time, the air mix damper 150 closes the bypass passage 122, so the air heated by the heater core 21 passes through the heater core passage 121, and the vehicle interior is heated.

[0052] The low-temperature side heat transfer medium circuit 30, through which the heat transfer medium exchanged in the low-temperature side heat exchanger 14 flows, is configured as follows: The three-way valve V30 forms heat transfer medium flow paths 30a and 30f so that the heat transfer medium cooled by heat exchange in the low-temperature side heat exchanger 14 bypasses the cooler core 31. The flow path switching device 71 connects the flow paths of the low-temperature side heat transfer medium circuit 30 and the outdoor heat exchange circuit 60, forming a circulation path through which the low-temperature side heat transfer medium circuit 30 and the outdoor heat exchange circuit 60 cooperate to circulate the heat transfer medium. Specifically, the heat transfer medium flow paths 30a and 30f of the low-temperature side heat transfer medium circuit 30 are connected to the heat transfer medium flow paths 60c, 60a, and 60b passing through the radiator 61, and the heat transfer medium flow paths 30g, 30h, and 30e and heat transfer medium flow paths 30g, 30i, 30d, and 30e of the low-temperature side heat transfer medium circuit 30, and the heat transfer medium circulates through these circulation paths.

[0053] As a result, the heat transfer medium that dissipates heat in the low-temperature heat exchanger 14 absorbs heat from the outside air in the radiator 61. Then, the refrigerant in the refrigerant circuit 10 absorbs heat from the heat transfer medium that has absorbed heat from the outside air in the radiator 61. In this way, the refrigerant circuit 10 operates and heat exchange occurs between the low-temperature heat exchanger 14 and the radiator 61. As a result, the air conditioning in the vehicle cabin is operated using outside air heat absorption heating.

[0054] Thus, heating operation is an operating mode in which the radiator 61, which is the outside air heat exchange unit, exchanges heat with the outside air. During heating operation, the high-temperature side heat exchanger 12 and the heater core 21 function as the utilization side heat exchange unit, and the low-temperature side heat exchanger 14 and the radiator 61 function as the heat source side heat exchange unit. In other words, there is a utilization side heat exchange unit in which the heat transfer medium that has exchanged heat with either the high-temperature side heat exchanger 12 or the low-temperature side heat exchanger 14 flows through the heat exchanger to exchange heat with the air blown into the vehicle interior, and a heat source side heat exchange unit in which the heat transfer medium that has exchanged heat with the other of the high-temperature side heat exchanger 12 or the low-temperature side heat exchanger 14 flows through the outside air heat exchange unit.

[0055] The flow path switching device 71 connects the flow paths of the battery temperature control circuit 40 and the motor temperature control circuit 50, forming a circulation path in which the battery temperature control circuit 40 and the motor temperature control circuit 50 cooperate to circulate the heat transfer medium. Specifically, the heat transfer medium flow paths 40a and 40b of the battery temperature control circuit 40 that pass through the battery 41 and the heat transfer medium flow paths 50a and 50b of the motor temperature control circuit 50 that pass through the motor 51 are connected, and the heat transfer medium circulates through these circulation paths.

[0056] As a result, the battery 41 is temperature-controlled by the heat of the heat transfer medium that absorbs the waste heat from the motor 51. In this case, the heat transfer medium may be heated by the heat transfer medium heating device 42 if necessary.

[0057] <Control of the refrigeration cycle during heating operation> During heating operation, the control device 200 controls the state of the refrigerant in the refrigeration circuit 10 by executing the controls shown in (1) to (4) below, thereby controlling the refrigeration cycle.

[0058] (1) The control device 200 controls the refrigerant outlet pressure Pci, which is the pressure of the refrigerant at the outlet of the high-temperature side heat exchanger 12, by controlling the rotational speed of the compressor 11, so that the refrigerant outlet pressure Pci reaches the target value. The target value of the refrigerant outlet pressure Pci is determined based on the discharge temperature required by the vehicle. In other words, the rotational speed of the compressor 11 is determined by the requirements of the heater core 21, which is the heat exchange section on the user side.

[0059] In this embodiment, an example is given in which the refrigerant outlet pressure Pci is controlled by controlling the rotational speed of the compressor 11, but it may also be controlled by means other than controlling the rotational speed of the compressor 11. Means other than controlling the rotational speed of the compressor 11 include, for example, adjusting the flow rate of the heat transfer medium by a control valve installed in the heat transfer medium passage 20a or by a circulation pump P20. In this case, by adjusting the amount of heat transfer medium flowing through the heat transfer medium passage 12b of the high-temperature side heat exchanger 12 with the control valve, the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 can be adjusted, and the refrigerant outlet pressure Pci can be adjusted.

[0060] (2) The control device 200 controls the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 by adjusting the opening of the pressure reducing device 13a based on the refrigerant outlet temperature Tci and the refrigerant outlet pressure Pci, so that the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 reaches the target value. The target value of the degree of subcooling SC is determined based on the outlet temperature required by the vehicle. In other words, the degree of subcooling SC is determined by the requirements of the heater core 21, which is the heat exchanger on the user side.

[0061] (3) The control device 200 controls the suction pressure Ps of the compressor 11 to reach the target value by adjusting the opening of the pressure reducing device 13b in the bypass path.

[0062] Furthermore, increasing the suction pressure Ps increases the density of the refrigerant drawn into the compressor 11, thereby improving the output of the compressor 11. Also, increasing the suction pressure Ps reduces the pressure ratio with the pressure of the refrigerant discharged by the compressor 11, thereby improving the compression efficiency of the refrigerant in the compressor 11. On the other hand, if the suction pressure Ps is made too high, heat absorption becomes difficult in the low-temperature side heat exchanger 14. Therefore, the control device 200 determines a target value for the suction pressure Ps based on the detected ambient temperature.

[0063] (4) The control device 200 controls the intake temperature Ts of the compressor 11 to reach the target value by adjusting the opening of the pressure reducing device 13c in the bypass path.

[0064] Furthermore, by adjusting the rotational speed of the compressor 11 in the control described in (1) above, the refrigerant pressure during compression in the refrigeration cycle, i.e., the refrigerant pressure Pd discharged by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13a in the control described in (2) above, the refrigerant temperature during condensation in the refrigeration cycle, i.e., the refrigerant temperature Tp discharged by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the opening degree of the pressure reducing device 13b in the control described in (3) above, the refrigerant pressure during depressurization in the refrigeration cycle, i.e., the refrigerant pressure Ps drawn in by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the opening degree of the pressure reducing device 13c in the control described in (4) above, the refrigerant temperature during evaporation in the refrigeration cycle, i.e., the refrigerant temperature Ts drawn in by the compressor 11, is adjusted to the target value. Note that the target value of the refrigerant pressure during compression is determined based on the blow-off temperature required by the vehicle.

[0065] Here, we will explain the problems that may occur during the operating mode in which the radiator 61, which is the outside air heat exchange unit, exchanges heat with the outside air. If the heat load fluctuates due to disturbances such as fluctuations in outside temperature during the operating mode in which the radiator 61, which is the outside air heat exchange unit, fluctuates, the pressure circulating in the refrigerant circuit 10 fluctuates, and the temperature of the air blown into the vehicle interior fluctuates.

[0066] For example, during heating operation, if the outside temperature drops (when the heat load increases due to disturbances), the temperature of the heat transfer medium exchanged in the radiator 61 decreases. Consequently, the temperature of the heat transfer medium passing through the low-temperature heat exchanger 14 decreases, which reduces the pressure of the refrigerant exchanging heat with the heat transfer medium in the low-temperature heat exchanger 14, and thus the pressure of the refrigerant circulating in the refrigerant circuit 10 decreases. As a result, the pressure (condensation pressure) of the refrigerant exchanging heat in the high-temperature heat exchanger 12 decreases, and consequently, the temperature of the heat transfer medium exchanging heat in the high-temperature heat exchanger 12 decreases, and the temperature of the heat transfer medium passing through the heater core 21 decreases. Therefore, the temperature of the air blown into the passenger compartment decreases.

[0067] For example, during heating operation, if the outside temperature rises (when the heat load decreases due to disturbances), the temperature of the heat transfer medium exchanged in the radiator 61 rises. Consequently, the temperature of the heat transfer medium passing through the low-temperature heat exchanger 14 rises, causing the pressure of the refrigerant exchanging heat with the heat transfer medium in the low-temperature heat exchanger 14 to rise, and the pressure of the refrigerant circulating in the refrigerant circuit 10 to rise. As a result, the pressure (condensation pressure) of the refrigerant exchanging heat in the high-temperature heat exchanger 12 rises, and consequently, the temperature of the heat transfer medium exchanged in the high-temperature heat exchanger 12 rises, causing the temperature of the heat transfer medium passing through the heater core 21 to rise. Therefore, the temperature of the refrigerant discharged into the passenger compartment rises.

[0068] In contrast, conventionally, the refrigerant pressure during compression and the refrigerant temperature during condensation were controlled, for example, by controlling the rotational speed of the compressor 11 and the opening degree of the pressure reducing device 13a that does not bypass the high-temperature side heat exchanger 12, so that the refrigerant pressure during compression and the refrigerant temperature during condensation in the refrigeration cycle would reach target values.

[0069] Therefore, when the outside temperature dropped, the rotational speed of the compressor 11 was increased to restore the refrigerant pressure during compression to the target value, thereby increasing the refrigerant pressure (condensation pressure) in the high-temperature side heat exchanger 12.

[0070] On the other hand, if the outside temperature rose, the rotational speed of the compressor 11 was reduced to return the refrigerant pressure during compression to the target value, thereby lowering the refrigerant pressure (condensation pressure) in the high-temperature side heat exchanger 12.

[0071] In this manner, when a disturbance occurs, the state of the refrigerant flowing through the high-temperature heat exchanger 12 is controlled by restoring the refrigerant pressure during compression and the refrigerant temperature during condensation in the refrigeration cycle to target values, thereby restoring the discharge temperature into the vehicle interior to the target temperature.

[0072] However, after the refrigerant pressure during compression and the refrigerant temperature during condensation in the refrigeration cycle return to their target values, the refrigerant pressure during depressurization and the refrigerant temperature during evaporation stabilize as a result. Therefore, it takes time for the refrigeration cycle to return to its state before the disturbance and stabilize. Consequently, it takes time for the discharge temperature inside the vehicle to stabilize, and the duration of discharge temperature fluctuations is long.

[0073] Therefore, in this embodiment, by controlling the intake pressure Ps and intake temperature Ts so that they reach target values, the refrigerant pressure during compression and the refrigerant temperature during condensation are controlled simultaneously to reach target values, as well as the refrigerant pressure during depressurization (= intake pressure Ps) and the refrigerant temperature during evaporation (= intake temperature Ts). As a result, even if the heat load fluctuates due to disturbances, the time it takes for the refrigeration cycle to return to its pre-disturbance state and stabilize can be shortened. In other words, the robustness of the vehicle air conditioning system 1 can be improved. This makes it possible to suppress fluctuations in the discharge temperature and prevent deterioration of occupant comfort.

[0074] Furthermore, considering that the energy efficiency of the compressor 11 improves as the difference between the discharge pressure Pd and the suction pressure Ps of the compressor 11 decreases, the refrigeration cycle can be circulated in such a way that the energy efficiency of the compressor 11 is improved by controlling the suction pressure Ps. In other words, the system efficiency of the vehicle air conditioning system 1 can be improved.

[0075] <Air conditioning operation> Figure 2 shows the circuit state of the vehicle air conditioning system 1 when the cooling operation is performed when the outside temperature is high.

[0076] As shown in Figure 2, when performing cooling operation, the refrigerant circuit 10 is set as follows: the pressure reducing device 13a is opened. This forms refrigerant flow paths 10a, 10b, 10c, 10d, 10e, and 10f so that the refrigerant discharged from the discharge side 11a of the compressor 11 flows into the suction side 11b of the compressor 11 via the high-temperature side heat exchanger 12 and the low-temperature side heat exchanger 14.

[0077] Furthermore, the pressure reducing device 13b is completely closed, and the pressure reducing device 13c is opened. This forms refrigerant flow paths 10a, 10h, and 10f so that the refrigerant discharged from the discharge side 11a of the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11.

[0078] As a result, a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature heat exchanger 12 and flows into a bypass path that flows upstream of the compressor 11, while the remaining refrigerant that does not flow into the bypass path flows into the high-temperature heat exchanger 12.

[0079] The low-temperature side heat transfer medium circuit 30, through which the heat transfer medium that undergoes heat exchange in the low-temperature side heat exchanger 14 flows, is configured as follows: The flow path switching device 71 disconnects the low-temperature side heat transfer medium circuit 30 from the outdoor heat exchange circuit 60. The three-way valve V30 forms heat transfer medium flow paths 30a, 30b, 30c, 30d, 30e, and 30f so that the heat transfer medium cooled by heat exchange in the low-temperature side heat exchanger 14 flows through the cooler core 31.

[0080] As a result, the heat transfer medium that dissipates heat in the low-temperature heat exchanger 14 exchanges heat with the cooler core 31, thereby cooling the vehicle interior. At this time, the air mix damper 150 closes the heater core passage 121, so the air cooled by the cooler core 31 passes through the bypass passage 122, and the vehicle interior is cooled.

[0081] The high-temperature side heat transfer medium circuit 20, through which the heat transfer medium exchanged in the high-temperature side heat exchanger 12 flows, is configured as follows: The four-way valve V20 connects the high-temperature side heat transfer medium circuit 20 to the outdoor heat exchange circuit 60, and the outdoor heat exchange circuit 60 and the high-temperature side heat transfer medium circuit 20 work together to form a circulation path that circulates the heat transfer medium.

[0082] As a result, the heat transfer medium absorbed by the high-temperature heat exchanger 12 is released to the outside air by the radiator 61. Then, the refrigerant in the refrigerant circuit 10 releases heat using the heat transfer medium released by the radiator 61 as the heat source. In this way, the refrigerant circuit 10 operates, and heat exchange occurs between the high-temperature heat exchanger 12 and the radiator 61. As a result, the air conditioning in the vehicle cabin operates in cooling mode.

[0083] Thus, the cooling operation is an operating mode in which the radiator 61, which is the outside air heat exchange unit, exchanges heat with the outside air. During cooling operation, the low-temperature side heat exchanger 14 and the cooler core 31 function as the utilization side heat exchange unit, and the high-temperature side heat exchanger 12 and the radiator 61 function as the heat source side heat exchange unit. In other words, there is a utilization side heat exchange unit in which the heat transfer medium that has exchanged heat with either the high-temperature side heat exchanger 12 or the low-temperature side heat exchanger 14 flows through the heat exchanger to exchange heat with the air blown into the passenger compartment, and a heat source side heat exchange unit in which the heat transfer medium that has exchanged heat with the other of the high-temperature side heat exchanger 12 or the low-temperature side heat exchanger 14 flows through the outside air heat exchange unit.

[0084] The flow path switching device 71 connects the flow paths of the low-temperature side heat transfer medium circuit 30, the battery temperature control circuit 40, and the motor temperature control circuit 50, forming a circulation path in which the low-temperature side heat transfer medium circuit 30, the battery temperature control circuit 40, and the motor temperature control circuit 50 cooperate to circulate the heat transfer medium. Specifically, the heat transfer medium flow paths 30a and 30f of the low-temperature side heat transfer medium circuit 30 are connected to the heat transfer medium flow paths 40a and 40b of the battery temperature control circuit 40 that pass through the battery 41, the heat transfer medium flow paths 50a and 50b of the motor temperature control circuit 50 that pass through the motor 51, and the heat transfer medium flow paths 30g, 30h, and 30e and heat transfer medium flow paths 30g, 30i, 30d, and 30e of the low-temperature side heat transfer medium circuit 30, allowing the heat transfer medium to circulate through these circulation paths.

[0085] As a result, the battery 41 and motor 51 can be temperature-controlled by the heat transfer medium that is exhausted by the low-temperature side heat exchanger 14.

[0086] <Control of the refrigeration cycle during cooling operation> During cooling operation, the control device 200 controls the state of the refrigerant in the refrigeration circuit 10 by executing the controls shown in (1) to (4) below, thereby controlling the refrigeration cycle. In addition, during cooling operation, the control device 200 completely closes the pressure reducing device 13b and does not use the pressure reducing device 13b to control the refrigeration cycle.

[0087] (1) The control device 200 controls the outlet temperature Te of the air that has passed through the cooler core 31 (air at the outlet of the cooler core 31) by controlling the rotational speed of the compressor 11 so that the outlet temperature Te of the air that has passed through the cooler core 31 reaches the target value. The target value of the outlet temperature Te is set based on the blown-out temperature requested by the vehicle. In other words, the rotational speed of the compressor 11 is determined by the requirements of the cooler core 31, which is the heat exchanger on the user side.

[0088] (2) The control device 200 controls the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 by adjusting the opening of the pressure reducing device 13a based on the refrigerant outlet temperature Tci and the refrigerant outlet pressure Pci, so that the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 reaches the target value. The target value of the degree of subcooling SC is determined based on the outlet temperature required by the vehicle. In other words, the degree of subcooling SC is determined by the requirements of the cooler core 31, which is the heat exchange section on the user side.

[0089] (3) The control device 200 controls the intake temperature Ts of the compressor 11 to reach the target value by adjusting the opening of the pressure reducing device 13c in the bypass path.

[0090] (4) The control device 200 controls the refrigerant outlet pressure Pci, which is the pressure of the refrigerant at the outlet of the high-temperature heat exchanger 12, by controlling the rotation speed of the circulation pump P20, so that the refrigerant outlet pressure Pci reaches the target value.

[0091] Since the ambient temperature is determined spontaneously, a target value is set by estimating the refrigerant outlet pressure Pci (in other words, the discharge pressure Pd of the compressor 11) that can be managed based on the ambient temperature, and the high-pressure side is controlled accordingly. Since the ambient temperature is determined spontaneously, the amount of heat dissipated in the high-temperature side heat exchanger 12 is adjusted by setting the refrigerant outlet pressure Pci according to the ambient temperature. In order to improve the compression efficiency of the compressor 11, it is preferable to keep the discharge pressure Pd of the compressor 11 as low as possible.

[0092] In this embodiment, an example is given in which the refrigerant outlet pressure Pci is controlled by controlling the rotational speed of the circulation pump P20, but it may also be controlled by means other than controlling the rotational speed of the circulation pump P20. Means other than controlling the rotational speed of the circulation pump P20 include, for example, adjusting the flow rate of the heat transfer medium by a control valve installed in the heat transfer medium passage 20a. In this case, by adjusting the amount of heat transfer medium flowing through the heat transfer medium passage 12b of the high-temperature side heat exchanger 12 with the control valve, the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 can be adjusted, and the refrigerant outlet pressure Pci can be adjusted. Another example is blowing air to the radiator 61 with a radiator fan. In this case, by adjusting the temperature of the heat transfer medium passing through the radiator 61 with the air blown by the radiator fan, the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 can be adjusted, and the refrigerant outlet pressure Pci can be adjusted. Another example is opening and closing the radiator 61 with a grill shutter. In this case, the temperature of the heat transfer medium passing through the radiator 61 can be adjusted by the change in ram pressure associated with the opening and closing of the grill shutter, thereby adjusting the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature heat exchanger 12, and thus adjusting the refrigerant outlet pressure Pci.

[0093] Then, by adjusting the rotation speed of the circulation pump P20 in the control described in (4) above, the refrigerant pressure during compression in the refrigeration cycle, i.e., the refrigerant pressure Pd discharged by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13a in the control described in (2) above, the refrigerant temperature during condensation in the refrigeration cycle, i.e., the refrigerant temperature Tp discharged by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the rotation speed of the compressor 11 and the opening degree of the pressure reducing device 13a in the control described in (1) and (2) above, the refrigerant pressure during depressurization in the refrigeration cycle, i.e., the refrigerant pressure Ps drawn in by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the opening degree of the pressure reducing device 13c in the control described in (3) above, the refrigerant temperature during evaporation in the refrigeration cycle, i.e., the refrigerant temperature Ts drawn in by the compressor 11, is adjusted to the target value. Note that the target value of the refrigerant pressure during depressurization is determined based on the blow-off temperature required by the vehicle.

[0094] Here, we will explain the problems that may occur during the operating mode in which the radiator 61, which is the outside air heat exchange unit, exchanges heat with the outside air. If the heat load fluctuates due to disturbances such as fluctuations in outside temperature during the operating mode in which the radiator 61, which is the outside air heat exchange unit, fluctuates, the pressure circulating in the refrigerant circuit 10 fluctuates, and the temperature of the air blown into the vehicle interior fluctuates.

[0095] For example, during air conditioning operation, if the outside temperature rises (when the heat load increases due to disturbances), the temperature of the heat transfer medium exchanged in the radiator 61 rises. Consequently, the temperature of the heat transfer medium passing through the high-temperature side heat exchanger 12 rises, causing the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 to rise, and the pressure of the refrigerant circulating in the refrigerant circuit 10 to rise. As a result, the pressure (evaporation pressure) of the refrigerant exchanging heat in the low-temperature side heat exchanger 14 rises, and consequently, the temperature of the heat transfer medium exchanging heat in the low-temperature side heat exchanger 14 rises, causing the temperature of the heat transfer medium passing through the cooler core 31 to rise. Therefore, the temperature of the air blown into the passenger compartment rises.

[0096] For example, during air conditioning operation, if the outside temperature drops (when the heat load decreases due to an external disturbance), the temperature of the heat transfer medium exchanged in the radiator 61 decreases. Consequently, the temperature of the heat transfer medium passing through the high-temperature side heat exchanger 12 decreases, which reduces the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12, and thus the pressure of the refrigerant circulating in the refrigerant circuit 10 decreases. As a result, the pressure (evaporation pressure) of the refrigerant exchanging heat in the low-temperature side heat exchanger 14 decreases, and consequently, the temperature of the heat transfer medium exchanging heat in the low-temperature side heat exchanger 14 decreases, and the temperature of the heat transfer medium passing through the cooler core 31 decreases. Therefore, the temperature of the air blown into the passenger compartment decreases.

[0097] In contrast, conventionally, the temperature of the refrigerant during condensation and the pressure of the refrigerant during depressurization in the refrigeration cycle were controlled, for example, by controlling the rotational speed of the compressor 11 and the opening degree of the depressurization device 13a that does not bypass the high-temperature side heat exchanger 12, so that the refrigerant temperature during condensation and the pressure of the refrigerant during depressurization in the refrigeration cycle would reach target values.

[0098] Therefore, when the outside temperature dropped, the rotational speed of the compressor 11 was increased to restore the refrigerant temperature during condensation and the refrigerant pressure during depressurization to the target values, thereby lowering the refrigerant pressure (evaporation pressure) in the low-temperature side heat exchanger 14.

[0099] On the other hand, when the outside temperature rose, the rotational speed of the compressor 11 was reduced to return the refrigerant temperature during condensation and the refrigerant pressure during depressurization to the target values, thereby increasing the refrigerant pressure (evaporation pressure) in the low-temperature side heat exchanger 14.

[0100] In this way, by restoring the refrigerant temperature during condensation and the refrigerant pressure during depressurization in the refrigeration cycle to target values, the state of the refrigerant flowing through the low-temperature heat exchanger 14 was controlled, and the discharge temperature into the vehicle interior was restored to the target temperature.

[0101] However, in the refrigeration cycle, after the refrigerant temperature during condensation and the refrigerant pressure during depressurization return to their target values, the refrigerant pressure during compression and the refrigerant temperature during evaporation stabilize as a result. Therefore, it takes time for the refrigeration cycle to return to its state before the disturbance and stabilize. Consequently, it takes time for the discharge temperature inside the vehicle to stabilize, and the duration of discharge temperature fluctuations is long.

[0102] Therefore, in this embodiment, by controlling the refrigerant outlet pressure Pci and the intake temperature Ts to their respective target values, the refrigerant temperature during condensation and the refrigerant pressure during depressurization are controlled simultaneously to reach target values, as well as the refrigerant pressure during compression (=refrigerant outlet pressure Pci) and the refrigerant temperature during evaporation (=intake temperature Ts). As a result, even if the heat load fluctuates due to disturbances, the time it takes for the refrigeration cycle to return to its pre-disturbance state and stabilize can be shortened. In other words, the robustness of the vehicle air conditioning system 1 can be improved. This makes it possible to suppress fluctuations in the discharge temperature and prevent deterioration of occupant comfort.

[0103] Furthermore, considering that the energy efficiency of the compressor 11 improves as the difference between the discharge pressure Pd and the suction pressure Ps of the compressor 11 decreases, the refrigeration cycle can be circulated in such a way that the energy efficiency of the compressor 11 is improved by controlling the suction pressure Ps. In other words, the system efficiency of the vehicle air conditioning system 1 can be improved.

[0104] [Example 1] Next, Modification 1 of the above embodiment will be described with reference to Figures 3 and 4. Note that components identical to those in the above embodiment will be described using the same reference numerals. Modification 1 differs in that it includes a refrigerant circuit 70 having a liquid receiver 16 instead of an accumulator 15. The heat transfer medium circuit is the same as in the above embodiment.

[0105] <Refrigerant Circuit> As shown in Figure 3, the refrigerant circuit 70 includes a compressor 11, a high-temperature side heat exchanger 12, pressure reducing devices 13a and 13b, and a low-temperature side heat exchanger 14.

[0106] The discharge side 11a of the compressor 11 is connected to the inlet of the refrigerant passage 12a of the high-temperature heat exchanger 12 via the refrigerant passage 70a connected thereto, branch point a1, and the downstream refrigerant passage 70b. The outlet of the refrigerant passage 12a of the high-temperature heat exchanger 12 is connected to the inlet of the refrigerant passage 14a of the low-temperature heat exchanger 14 via the refrigerant passage 70c. A pressure reducing device 13a, which serves as a first pressure reducing device, is installed along the path of the refrigerant passage 70c. A liquid receiver 16 is also installed along the path of the refrigerant passage 70c. The liquid receiver 16 temporarily stores the refrigerant liquefied in the high-temperature heat exchanger 12, separates the gaseous refrigerant from the liquid refrigerant, and supplies only the liquid refrigerant. The liquid receiver 16, also known as an RD (receiver dryer), removes moisture from the refrigerant by passing it through a desiccant.

[0107] Furthermore, the outlet of the refrigerant passage 14a of the low-temperature heat exchanger 14 is connected to the suction side 11b of the compressor 11 via the refrigerant passage 70d connected thereto, the confluence point b1, and the downstream refrigerant passage 70e.

[0108] Furthermore, the discharge side 11a of the compressor 11 is connected to the suction side 11b of the compressor 11 via a refrigerant flow path 70a, branch point a1, refrigerant flow path 70f, confluence point b1, and the downstream refrigerant flow path 70e. A pressure reducing device 13b, acting as a second pressure reducing device, is installed along the path of the refrigerant flow path 70g.

[0109] As described above, the refrigerant flow paths 70a, 70f, and 70e function as bypass paths through which a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature heat exchanger 12 and flows to the upstream side of the compressor 11.

[0110] [System operation] The specific operation of the vehicle air conditioning system 1 according to Modification 1 will be explained with reference to Figures 3 and 4.

[0111] <Heater operation> Figure 3 shows the circuit state of the vehicle air conditioning system 1 when heating operation is performed.

[0112] As shown in Figure 3, when performing heating operation, the refrigerant circuit 70 is set as follows: the pressure reducing device 13a is opened. This forms refrigerant flow paths 70a, 70b, 70c, 70d, and 70e so that the refrigerant discharged from the discharge side 11a of the compressor 11 flows into the suction side 11b of the compressor 11 via the high-temperature side heat exchanger 12 and the low-temperature side heat exchanger 14.

[0113] Furthermore, the pressure reducing device 13b is opened. This forms refrigerant flow paths 70a, 70f, and 70e so that the refrigerant discharged from the discharge side 11a of the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11.

[0114] As a result, a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature heat exchanger 12 and flows into a bypass path that flows upstream of the compressor 11, while the remaining refrigerant that does not flow into the bypass path flows into the high-temperature heat exchanger 12. The refrigerant flowing into the bypass path has a higher pressure when it returns to the suction side 11b of the compressor 11 compared to the refrigerant that passes through the high-temperature heat exchanger 12. By increasing the pressure of the refrigerant drawn into the compressor 11, it becomes possible to raise the temperature of the refrigerant discharged by the compressor 11, thereby improving heating capacity.

[0115] The high-temperature side heat transfer circuit 20, the low-temperature side heat transfer circuit 30, the battery temperature control circuit 40, the motor temperature control circuit 50, and the outdoor heat exchange circuit 60 are configured as shown in Figure 1.

[0116] <Control of the refrigeration cycle during heating operation> During heating operation, the control device 200 controls the state of the refrigerant in the refrigeration circuit 10 by executing the controls shown in (1) to (3) below, thereby controlling the refrigeration cycle.

[0117] (1) The control device 200 controls the refrigerant outlet pressure Pci, which is the pressure of the refrigerant at the outlet of the high-temperature side heat exchanger 12, by controlling the rotational speed of the compressor 11, so that the refrigerant outlet pressure Pci reaches the target value. The target value of the refrigerant outlet pressure Pci (condensation pressure) is determined based on the blow-off temperature required by the vehicle. In other words, the rotational speed of the compressor 11 is determined by the requirements of the heater core 21, which is the heat exchange section on the user side.

[0118] In this embodiment, an example is given in which the refrigerant outlet pressure Pci is controlled by controlling the rotational speed of the compressor 11, but it may also be controlled by means other than controlling the rotational speed of the compressor 11. Means other than controlling the rotational speed of the compressor 11 include, for example, adjusting the flow rate of the heat transfer medium by a control valve installed in the heat transfer medium passage 20a or by a circulation pump P20. In this case, by adjusting the amount of heat transfer medium flowing through the heat transfer medium passage 12b of the high-temperature side heat exchanger 12 with the control valve, the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 can be adjusted, and the refrigerant outlet pressure Pci can be adjusted.

[0119] (2) The control device 200 controls the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 by adjusting the opening of the pressure reducing device 13a based on the refrigerant outlet temperature Tci and the refrigerant outlet pressure Pci, so that the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 becomes a target value. In other words, the degree of subcooling SC is determined by the requirements of the heater core 21, which is the heat exchanger on the utilization side.

[0120] (3) The control device 200 controls the intake pressure Ps and intake temperature Ts of the compressor 11 by adjusting the opening of the pressure reducing device 13b in the bypass path so that the intake pressure Ps and intake temperature Ts of the compressor 11 become the target values.

[0121] Furthermore, increasing the suction pressure Ps increases the density of the refrigerant drawn into the compressor 11, thereby improving the output of the compressor 11. Also, increasing the suction pressure Ps reduces the pressure ratio between the refrigerant discharged by the compressor 11 and the discharge pressure Pd, thereby improving the compression efficiency of the refrigerant in the compressor 11. On the other hand, if the suction pressure Ps is set too high, heat absorption becomes difficult in the low-temperature side heat exchanger 14. Therefore, the control device 200 determines a target value for the suction pressure Ps based on the detected ambient temperature.

[0122] Then, by adjusting the rotational speed of the compressor 11 in the control described in (1) above, the refrigerant pressure during compression in the refrigeration cycle, i.e., the refrigerant pressure Pd discharged by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13a in the control described in (2) above, the refrigerant temperature during condensation in the refrigeration cycle, i.e., the refrigerant temperature Tp discharged by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13b in the control described in (3) above, the refrigerant pressure during depressurization in the refrigeration cycle, i.e., the refrigerant pressure Ps drawn in by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13b in the control described in (3) above, the refrigerant temperature during evaporation in the refrigeration cycle, i.e., the refrigerant temperature Ts drawn in by the compressor 11, is adjusted to the target value. Note that the target value of the refrigerant pressure during compression is determined based on the blow-off temperature required by the vehicle.

[0123] For the same reasons as in the above embodiment, even when the heat load fluctuates due to disturbances, the time it takes for the refrigeration cycle to return to its pre-disturbance state and stabilize can be shortened. In other words, the robustness of the vehicle air conditioning system 1 can be improved. This makes it possible to suppress fluctuations in the discharge temperature and prevent deterioration of occupant comfort.

[0124] Furthermore, considering that the energy efficiency of the compressor 11 improves as the difference between the discharge pressure Pd and the suction pressure Ps of the compressor 11 decreases, the refrigeration cycle can be circulated in such a way that the energy efficiency of the compressor 11 is improved by controlling the suction pressure Ps. In other words, the system efficiency of the vehicle air conditioning system 1 can be improved.

[0125] <Air conditioning operation> Figure 4 shows the circuit state of the vehicle air conditioning system 1 when the cooling operation is performed when the outside temperature is high.

[0126] As shown in Figure 4, when performing cooling operation, the refrigerant circuit 70 is set as follows: the pressure reducing device 13a is opened. This forms refrigerant flow paths 70a, 70b, 70c, 70d, and 70e so that the refrigerant discharged from the discharge side 11a of the compressor 11 flows into the suction side 11b of the compressor 11 via the high-temperature side heat exchanger 12 and the low-temperature side heat exchanger 14.

[0127] Furthermore, the pressure reducing device 13b is opened. This forms refrigerant flow paths 70a, 70f, and 70e so that the refrigerant discharged from the discharge side 11a of the compressor 11 bypasses the high-temperature side heat exchanger 12 and flows to the upstream side of the compressor 11.

[0128] As a result, a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature heat exchanger 12 and flows into a bypass path that flows upstream of the compressor 11, while the remaining refrigerant that does not flow into the bypass path flows into the high-temperature heat exchanger 12.

[0129] The high-temperature side heat transfer circuit 20, the low-temperature side heat transfer circuit 30, the battery temperature control circuit 40, the motor temperature control circuit 50, and the outdoor heat exchange circuit 60 are configured as shown in Figure 2.

[0130] <Control of the refrigeration cycle during cooling operation> During cooling operation, the control device 200 controls the state of the refrigerant in the refrigeration circuit 10 by executing the controls shown in (1) to (4) below, thereby controlling the refrigeration cycle.

[0131] (1) The control device 200 controls the outlet temperature Te of the air that has passed through the cooler core 31 (air at the outlet of the cooler core 31) by controlling the rotational speed of the compressor 11 so that the outlet temperature Te of the air that has passed through the cooler core 31 reaches the target value. Accordingly, the intake pressure Ps of the compressor 11 is controlled so that the intake pressure Ps reaches the target value. The target value of the intake pressure Ps (evaporation pressure) of the compressor 11 is set based on the blow-off temperature required by the vehicle. In other words, the rotational speed of the compressor 11 is determined by the requirements of the cooler core 31, which is the heat exchanger on the user side.

[0132] (2) The control device 200 controls the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 by adjusting the opening of the pressure reducing device 13a based on the refrigerant outlet temperature Tci and the refrigerant outlet pressure Pci, so that the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 becomes a target value. In other words, the degree of subcooling SC is determined by the requirements of the cooler core 31, which is the heat exchanger on the utilization side.

[0133] (3) The control device 200 controls the intake temperature Ts of the compressor 11 to reach the target value by adjusting the opening of the pressure reducing device 13b in the bypass path.

[0134] Furthermore, increasing the suction pressure Ps increases the density of the refrigerant drawn into the compressor 11, thereby improving the output of the compressor 11. Also, increasing the suction pressure Ps reduces the pressure ratio between the refrigerant discharged by the compressor 11 and the discharge pressure Pd, thereby improving the compression efficiency of the refrigerant in the compressor 11. On the other hand, if the suction pressure Ps is set too high, heat absorption becomes difficult in the low-temperature side heat exchanger 14. Therefore, the control device 200 determines a target value for the suction pressure Ps based on the detected ambient temperature.

[0135] (4) The control device 200 controls the refrigerant outlet pressure Pci, which is the pressure of the refrigerant at the outlet of the high-temperature heat exchanger 12, by controlling the rotation speed of the circulation pump P20, so that the refrigerant outlet pressure Pci reaches the target value.

[0136] Since the ambient temperature is determined spontaneously, a target value is set by estimating the refrigerant outlet pressure Pci (in other words, the discharge pressure Pd of the compressor 11) that can be managed based on the ambient temperature, and the high-pressure side is controlled accordingly. Since the ambient temperature is determined spontaneously, the amount of heat dissipated in the high-temperature side heat exchanger 12 is adjusted by setting the refrigerant outlet pressure Pci according to the ambient temperature. In order to improve the compression efficiency of the compressor 11, it is preferable to keep the discharge pressure Pd of the compressor 11 as low as possible.

[0137] In this embodiment, an example is given in which the refrigerant outlet pressure Pci is controlled by controlling the rotational speed of the circulation pump P20, but it may also be controlled by means other than controlling the rotational speed of the circulation pump P20. Means other than controlling the rotational speed of the circulation pump P20 include, for example, adjusting the flow rate of the heat transfer medium by a control valve installed in the heat transfer medium passage 20a. In this case, by adjusting the amount of heat transfer medium flowing through the heat transfer medium passage 12b of the high-temperature side heat exchanger 12 with the control valve, the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 can be adjusted, and the refrigerant outlet pressure Pci can be adjusted. Another example is blowing air to the radiator 61 with a radiator fan. In this case, by adjusting the temperature of the heat transfer medium passing through the radiator 61 with the air blown by the radiator fan, the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature side heat exchanger 12 can be adjusted, and the refrigerant outlet pressure Pci can be adjusted. Another example is opening and closing the radiator 61 with a grill shutter. In this case, the temperature of the heat transfer medium passing through the radiator 61 can be adjusted by the change in ram pressure associated with the opening and closing of the grill shutter, thereby adjusting the pressure of the refrigerant exchanging heat with the heat transfer medium in the high-temperature heat exchanger 12, and thus adjusting the refrigerant outlet pressure Pci.

[0138] Furthermore, by adjusting the rotational speed of the circulation pump P20 in the control described in (4) above, the refrigerant pressure during compression in the refrigeration cycle, i.e., the refrigerant pressure Pd discharged by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13a in the control described in (2) above, the refrigerant temperature during condensation in the refrigeration cycle, i.e., the refrigerant temperature Tp discharged by the compressor 11, is adjusted to the target value. In addition, by adjusting the rotational speed of the compressor 11 and the opening degree of the pressure reducing device 13b in the control described in (1) and (2) above, the refrigerant pressure during depressurization in the refrigeration cycle, i.e., the refrigerant pressure Ps drawn in by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the opening degree of the pressure reducing device 13b in the control described in (3) above, the refrigerant temperature during evaporation in the refrigeration cycle, i.e., the refrigerant temperature Ts drawn in by the compressor 11, is adjusted to the target value. Note that the target value of the refrigerant pressure during depressurization is determined based on the blow-off temperature required by the vehicle.

[0139] As a result, even when the heat load fluctuates due to disturbances, the time it takes for the refrigeration cycle to return to its pre-disturbance state and stabilize can be shortened. In other words, the robustness of the vehicle air conditioning system 1 can be improved. This makes it possible to suppress fluctuations in the discharge temperature, and thus suppress deterioration of occupant comfort.

[0140] Furthermore, considering that the energy efficiency of the compressor 11 improves as the difference between the discharge pressure Pd and the suction pressure Ps of the compressor 11 decreases, the refrigeration cycle can be circulated in such a way that the energy efficiency of the compressor 11 is improved by controlling the suction pressure Ps. In other words, the system efficiency of the vehicle air conditioning system 1 can be improved.

[0141] [Differentiation 2] Next, a modified example 2 of the above embodiment will be described with reference to Figure 5. Note that components identical to those in the above embodiment will be described using the same reference numerals. Unlike the above embodiment, modified example 2 includes a refrigerant circuit 80 with one bypass path. The heat transfer medium circuit is the same as in the above embodiment.

[0142] <Refrigerant Circuit> As shown in Figure 5, the refrigerant circuit 80 includes a compressor 11, a high-temperature side heat exchanger 12, pressure reducing devices 13a and 13b, and a low-temperature side heat exchanger 14.

[0143] The discharge side 11a of the compressor 11 is connected to the inlet of the refrigerant passage 12a of the high-temperature heat exchanger 12 via the refrigerant passage 80a connected thereto, branch point a1, and the downstream refrigerant passage 80b. The outlet of the refrigerant passage 12a of the high-temperature heat exchanger 12 is connected to the inlet of the refrigerant passage 14a of the low-temperature heat exchanger 14 via the refrigerant passage 80c. A pressure reducing device 13a, which serves as a first pressure reducing device, is installed along the path of the refrigerant passage 80c.

[0144] Furthermore, the outlet of the refrigerant passage 14a of the low-temperature heat exchanger 14 is connected to the suction side 11b of the compressor 11 via the refrigerant passage 80d connected thereto, the confluence point b1, and the downstream refrigerant passage 80e. An accumulator 15 is installed along the path of the refrigerant passage 80e.

[0145] Furthermore, the discharge side 11a of the compressor 11 is connected to the suction side 11b of the compressor 11 via a refrigerant flow path 80a, a branching point a1, a refrigerant flow path 80f, a confluence point b1, and a downstream refrigerant flow path 80e. A pressure reducing device 13b, acting as a second pressure reducing device, is installed along the path of the refrigerant flow path 80f.

[0146] As described above, the refrigerant flow paths 80a, 80f, and 80e function as bypass paths through which a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature heat exchanger 12 and flows to the upstream side of the compressor 11.

[0147] <Control of the refrigeration cycle during heating and cooling operations> During heating and cooling operations, the control device 200 controls the state of the refrigerant in the refrigeration circuit 10 by executing the controls shown in (1) to (3) below, thereby controlling the refrigeration cycle.

[0148] (1) The control device 200 controls the refrigerant outlet pressure Pci, which is the pressure of the refrigerant at the outlet of the high-temperature side heat exchanger 12, by controlling the rotational speed of the compressor 11, so that the refrigerant outlet pressure Pci reaches the target value.

[0149] (2) The control device 200 controls the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 by adjusting the opening of the pressure reducing device 13a based on the refrigerant outlet temperature Tci and the refrigerant outlet pressure Pci, so that the degree of subcooling SC of the refrigerant at the outlet of the high-temperature heat exchanger 12 becomes a target value.

[0150] (3) The control device 200 controls the intake pressure Ps and intake temperature Ts of the compressor 11 by adjusting the opening of the pressure reducing device 13b in the bypass path so that the intake pressure Ps and intake temperature Ts of the compressor 11 become the target values.

[0151] Alternatively, the suction pressure Ps and suction temperature Ts of the compressor 11 may be controlled by heat exchange between the refrigerant flowing from the pressure reducing device 13b to the confluence point b1 and the refrigerant flowing from the outlet side of the accumulator 15 to the suction side 11b of the compressor 11. In this case, for example, heat exchange can be made between the refrigerant flowing from the pressure reducing device 13b to the confluence point b1 and the refrigerant flowing from the outlet side of the accumulator 15 to the suction side 11b of the compressor 11 by placing the refrigerant flow path 80e and the refrigerant flow path 80f adjacent to each other, or by providing an internal heat exchanger.

[0152] Furthermore, by adjusting the rotational speed of the compressor 11 in the control described in (1) above, the refrigerant pressure during compression in the refrigeration cycle, i.e., the refrigerant pressure Pd discharged by the compressor 11, is adjusted to the target value. Also, by adjusting the opening degree of the pressure reducing device 13a in the control described in (2) above, the refrigerant temperature during condensation in the refrigeration cycle, i.e., the refrigerant temperature Tp discharged by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the opening degree of the pressure reducing device 13b in the control described in (3) above, the refrigerant pressure during depressurization in the refrigeration cycle, i.e., the refrigerant pressure Ps drawn in by the compressor 11, is adjusted to the target value. Furthermore, by adjusting the opening degree of the pressure reducing device 13b in the control described in (3) above, the refrigerant temperature during evaporation in the refrigeration cycle, i.e., the refrigerant temperature Ts drawn in by the compressor 11, is adjusted to the target value.

[0153] [Other variations] In the embodiments described above, an indirect system was given as an example in which the high-temperature side heat exchanger 12 and heater core 21 and the low-temperature side heat exchanger 14 and cooler core 31 are used as the utilization side heat exchange section, and the air blown into the vehicle interior and the heat transfer medium exchange heat, while the high-temperature side heat exchanger 12 and radiator 61 and the low-temperature side heat exchanger 14 and radiator 61 are used as the heat source side heat exchange section, and the outside air and the heat transfer medium exchange heat. However, this embodiment may also be applied to a direct system in which an indoor condenser through which a refrigerant circulates is provided in the HVAC unit 100 instead of the heater core 21, and an evaporator through which a refrigerant circulates is provided in the HVAC unit 100 instead of the cooler core 31, and the indoor condenser and evaporator are used as the utilization side heat exchange section, and the air blown into the vehicle interior and the refrigerant exchange heat, while the indoor condenser and outdoor heat exchanger (outdoor air heat exchange section) and the evaporator and outdoor heat exchanger (outdoor air heat exchange section) are used as the heat source side heat exchange section, and the outside air and the refrigerant exchange heat.

[0154] [Effects of this embodiment] (1) A refrigerant circuit 10 comprising a compressor 11, a high-temperature side heat exchanger 12 as a condenser, a pressure reducing device 13a as a first pressure reducing device, pressure reducing devices 13b and 13c as second pressure reducing devices, and a bypass path through which a portion of the refrigerant discharged by the compressor 11 bypasses the high-temperature side heat exchanger 12 as a condenser and flows to the upstream side of the compressor 11, wherein the pressure reducing devices 13b and 13c as second pressure reducing devices are arranged on the bypass path. In a vehicle air conditioning system 1 that air-conditions the interior of a vehicle by operating a refrigerant circuit 10, exchanging heat in a heat source side heat exchange section including a radiator 61 which acts as an outside air heat exchange section that exchanges heat with the outside air, and exchanging heat in a utilization side heat exchange section, During the operating mode in which the radiator 61, acting as an outside air heat exchange unit, exchanges heat with the outside air, the state of the refrigerant drawn in by the compressor 11 and / or the refrigerant discharged by the compressor 11 is controlled so that at least the pressure and temperature of the refrigerant drawn in by the compressor 11 and the pressure of the refrigerant discharged by the compressor 11 reach target values. Therefore, when disturbances (fluctuations in heat load) occur, it becomes possible to maintain a constant pressure and temperature of the refrigerant drawn in by the compressor 11, thereby suppressing fluctuations in the refrigeration cycle. This makes it possible to suppress fluctuations in the discharge temperature, thereby suppressing deterioration of occupant comfort.

[0155] (2) The state of the refrigerant drawn in and / or discharged by the compressor is controlled by controlling the pressure reducing devices 13b and 13c as second pressure reducing devices. Therefore, since the rotational speed of the compressor 11 and the opening degree of the pressure reducing device 13a as the first pressure reducing device are determined by the requirements of the heat exchange section on the user side, when disturbances (fluctuations in heat load) occur, the state of the refrigerant flowing through the bypass path is controlled based on the state of the refrigerant drawn in by the compressor 11. By keeping the pressure and / or temperature of the refrigerant drawn in by the compressor 11 constant, fluctuations in the refrigeration cycle can be suppressed, and the refrigeration cycle can always be controlled under efficient operating conditions.

[0156] (3) The refrigerant circuit 10 has a low-temperature side heat exchanger 14 as an evaporator, The heat exchanger, which has exchanged heat with either the high-temperature side heat exchanger 12 as a condenser or the low-temperature side heat exchanger 14 as an evaporator, flows through a heat exchanger on the utilization side, and the heat transfer medium that has exchanged heat with the air supplied to the passenger compartment, The system includes a heat source side heat exchange section through which a heat transfer medium, which has exchanged heat with the other of either a high-temperature side heat exchanger 12 acting as a condenser or a low-temperature side heat exchanger 14 acting as an evaporator, flows. Therefore, even if disturbances (fluctuations in heat load) occur, the heat generated by the disturbance is transferred to the high-temperature side heat exchanger 12 or the low-temperature side heat exchanger 14 of the refrigerant circuit 10 via the heat transfer medium. This suppresses a rapid change in the amount of heat exchanged by the refrigerant in the heat exchanger that has become the heat source side heat exchange section. As a result, the impact on the control of the target value of the refrigerant circuit 10 can be reduced, and fluctuations in the refrigeration cycle can be further suppressed.

[0157] Although the present invention has been described above with reference to preferred embodiments, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention. [Explanation of Symbols]

[0158] 1: Vehicle air conditioning system 10, 70, 80: Refrigerant circuit 12:High temperature side heat exchanger 14: Low temperature side heat exchanger 21: Heater core 31: Coola Core 61: Radiator

Claims

1. The refrigerant circuit comprises a compressor, a condenser, a first pressure reducing device, a second pressure reducing device, and a bypass path through which a portion of the refrigerant discharged by the compressor bypasses the condenser and flows to the upstream side of the compressor, wherein the second pressure reducing device is located on the bypass path. In a vehicle air conditioning system that operates the refrigerant circuit to exchange heat in a heat source side heat exchange section, which includes an outside air heat exchange section that exchanges heat with the outside air, and then exchanges heat in a utilization side heat exchange section to air condition the interior of the vehicle, During the operating mode in which the outside air heat exchange unit exchanges heat with the outside air, the state of the refrigerant drawn in by the compressor and / or the refrigerant discharged by the compressor is controlled so that at least the pressure and temperature of the refrigerant drawn in by the compressor and the pressure of the refrigerant discharged by the compressor reach target values. A vehicle air conditioning system characterized by the following features.

2. The state of the refrigerant drawn in by the compressor and / or discharged by the compressor is controlled by controlling the second pressure reducing device. The vehicle air conditioning system according to feature 1.

3. The refrigerant circuit includes an evaporator, A heat exchange section on the user side, through which the heat transfer medium that has exchanged heat with either the condenser or the evaporator exchanges heat with the air blown into the vehicle cabin, The condenser, or the other of the evaporator, has a heat source side heat exchange section through which the heat transfer medium that has exchanged heat with the other flows. The vehicle air conditioning system according to claim 1, characterized in that it is a vehicle air conditioning system.

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