Temperature regulation system and method for controlling temperature regulation system

Abstract

Provided is a temperature regulation system (100) comprising a refrigerant circuit (10), a heat medium circuit (20), and a control unit (30). The heat medium circuit (20) includes an indoor air-conditioning heat exchanger (25b) and can set a condenser (12) and a first evaporator (14) so as to be in series with the indoor air-conditioning heat exchanger (25b). The control unit (30) can implement a heater mode in which the condenser (12) and the first evaporator (14) are placed in a series circuit with respect to the indoor air-conditioning heat exchanger (25b). In the heater mode, the control unit (30) performs control such that the pressure of refrigerant (RF) guided from the first evaporator (14) to the compressor (11) is equal to or less than a saturation pressure corresponding to the temperature of air passing through a second evaporator (18).

Description

Temperature control system and method for controlling the temperature control system

[0001] The present disclosure relates to a temperature control system suitable for use in a vehicle and a method for controlling a temperature control system.

[0002] A conventional vehicle thermal management system has been known that has an operating mode for quickly heating a device to be heated when the outside air temperature is low (see, for example, Patent Document 1). The vehicle thermal management system disclosed in Patent Document 1 circulates a refrigerant through a refrigeration cycle that includes a compressor, a coolant heater, an expansion valve, and a coolant cooler. The vehicle thermal management system supplies a heat medium heated by heat exchange with the refrigerant in the coolant heater to a heating heat exchanger to heat the air to be blown into the vehicle cabin, and supplies a heat medium cooled by heat exchange with the refrigerant in the coolant cooler to a radiator to dissipate heat from the coolant to the outside air.

[0003] JP 2014-201148 A

[0004] The vehicle thermal management system disclosed in Patent Document 1 has a refrigeration cycle that is composed of a compressor, a coolant heater, an expansion valve, and a coolant cooler, and does not have a cooling heat exchanger that exchanges heat between a low-pressure refrigerant and air during cooling.In order to provide a function of cooling the vehicle interior by exchanging heat between the refrigerant and the air being blown into the vehicle, for example, it is possible to provide a method in which a second expansion valve and a cooling heat exchanger that exchanges heat between the refrigerant expanded by the second expansion valve and the air being blown into the vehicle interior are provided in the refrigeration cycle.

[0005] However, when heating the vehicle interior, even though the cooling heat exchanger is not operating, some of the refrigerant circulating through the refrigeration cycle remains in the cooling heat exchanger, reducing the flow rate of the refrigerant circulating through the refrigeration cycle including the heating heat exchanger. In this case, the degree of superheat of the refrigerant drawn into the compressor increases, reducing the heating capacity, and ultimately making it impossible to continue continuous operation of the heating operation using the power of the compressor.

[0006] The present disclosure has been made in consideration of these circumstances, and aims to provide a temperature control system and a control method for a temperature control system that can prevent a decrease in heating capacity when executing a temperature control mode that uses the power of a compressor to heat the temperature control target, and can continue continuous operation of the temperature control mode.

[0007] A temperature adjustment system according to one aspect of the present disclosure includes a refrigerant circuit having a first circulation state in which a refrigerant circulates through a compressor, a high-pressure side heat exchanger, a first decompression unit, and a first low-pressure side heat exchanger, and a second circulation state in which the refrigerant circulates through the compressor, a second decompression unit, and a second low-pressure side heat exchanger; a heat medium circuit that circulates a heat medium that exchanges heat with the refrigerant through the high-pressure side heat exchanger and the first low-pressure side heat exchanger; and a control unit that controls the refrigerant circuit and the heat medium circuit, wherein the heat medium circuit is a temperature control circuit that controls a temperature control target using the heat medium. The system further includes a temperature control device, and the high-pressure side heat exchanger and the first low-pressure side heat exchanger can be configured to be in series with the temperature control device. The control unit sets the refrigerant circuit in the first circulation state and executes a temperature control mode in which the high-pressure side heat exchanger and the first low-pressure side heat exchanger are circuited in series with the temperature control device. In the temperature control mode, the control unit controls the pressure of the refrigerant introduced from the first low-pressure side heat exchanger to the compressor so that it is equal to or lower than a saturation pressure corresponding to the temperature of air passing through the second low-pressure side heat exchanger. Note that in the second circulation state, a heat dissipation heat exchanger that exchanges heat between the refrigerant and outside air may be used instead of the high-pressure side heat exchanger. The heat medium circuit may also be configured to have an operation mode in which the high-pressure side heat exchanger and the low-pressure side heat exchanger are in series with respect to the heat medium flow, a circuit that bypasses the low-pressure side heat exchanger, and a valve that adjusts the amount of heat medium flowing into the low-pressure side heat exchanger.

[0008] In a control method for a temperature adjustment system according to one aspect of the present disclosure, the temperature adjustment system includes a refrigerant circuit having a first circulation state in which a refrigerant circulates through a compressor, a high-pressure side heat exchanger, a first pressure reducing unit, and a first low-pressure side heat exchanger, and a second circulation state in which the refrigerant circulates through the compressor, a second pressure reducing unit, and a second low-pressure side heat exchanger, and a heat medium circuit that circulates a heat medium that exchanges heat with the refrigerant through the high-pressure side heat exchanger and the first low-pressure side heat exchanger, and the heat medium circuit has a temperature adjustment device that heats a temperature adjustment target using the heat medium. The high-pressure side heat exchanger and the first low-pressure side heat exchanger can be set so as to be in series with the temperature adjustment device, and a control process is provided in which the refrigerant circuit is set to the first circulation state and a temperature adjustment mode is executed in which the high-pressure side heat exchanger and the first low-pressure side heat exchanger are circuited in series with the temperature adjustment device, and the control process controls the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor so that it is equal to or lower than a saturation pressure corresponding to the temperature of air passing through the second low-pressure side heat exchanger in the temperature adjustment mode.

[0009] According to the present disclosure, it is possible to provide a temperature control system and a control method for a temperature control system that can prevent a decrease in heating capacity when executing a temperature control mode that uses the power of a compressor to heat the temperature control target, and can continue continuous operation of the temperature control mode.

[0010] FIG. 1 is a schematic configuration diagram showing a temperature adjustment system according to a first embodiment of the present disclosure, showing a state in which a heater mode is being executed; FIG. 2 is a flowchart showing a control method when the temperature adjustment system according to the first embodiment of the present disclosure executes the heater mode; FIG. 3 is a schematic configuration diagram showing a temperature adjustment system according to the first embodiment of the present disclosure, showing a state in which a heat pump mode is being executed; FIG. 4 is a schematic configuration diagram showing a temperature adjustment system according to a first embodiment of the present disclosure, showing a state in which a cooling mode is being executed; and FIG. 5 is a schematic configuration diagram showing a temperature adjustment system according to a second embodiment of the present disclosure, showing a state in which the heater mode is being executed.

[0011] First Embodiment A temperature control system 100 according to a first embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a schematic diagram showing the temperature control system 100 according to the first embodiment of the present disclosure, illustrating a state in which a heater mode is being executed. The vehicle temperature control system 100 shown in Fig. 1 is installed in a vehicle (not shown), such as an electric vehicle that does not have an engine and obtains driving force for vehicle travel from an electric motor, or a so-called hybrid vehicle that obtains driving force for vehicle travel from an engine and an electric motor.

[0012] The temperature adjustment system 100 is responsible for air conditioning such as heating and cooling, dehumidification, and ventilation of the passenger compartment, as well as heat management and exhaust heat recovery for on-board devices such as the battery device (power supply device) installed in the vehicle, the electric motor for driving, and heat-generating electronic devices. Conditioning the air to an appropriate temperature and humidity, and maintaining on-board devices at an appropriate temperature, are collectively referred to as "thermal management."

[0013] The temperature adjustment system 100 and the electrically powered devices and electronic devices provided in the on-board devices are supplied with power stored in an on-board battery device. The on-board battery device is charged from an external power source when the vehicle is stopped.

[0014] The temperature adjustment system 100 includes a refrigerant circuit 10 configured to allow refrigerant to circulate, a heat medium circuit 20 configured to allow a heat medium that transfers heat to and from the refrigerant to circulate, and a control unit 30 that sets the temperature adjustment system 100 to a predetermined operating mode and controls the operating state of the temperature adjustment system 100 in accordance with the operating mode. The temperature adjustment system 100 includes sensors (not shown), such as a sensor that detects the outside air temperature and a sensor that detects the temperature of conditioned air blown into the vehicle cabin.

[0015] The temperature adjustment system 100 can execute one of a plurality of operating modes selected by the occupant or the control unit 30. In this embodiment, the operating modes of the temperature adjustment system 100 are exemplified by a heater mode (FIG. 1), a heat pump mode (FIG. 3), and a cooling mode (FIG. 4).

[0016] <Configuration of Refrigerant Circuit 10> The refrigerant circuit 10 includes a compressor 11 that compresses the refrigerant RF, a condenser (high-pressure side heat exchanger) 12, a first expansion valve (first pressure reduction unit) 13, a first evaporator (first low-pressure side heat exchanger) 14, an accumulator 15, a temperature sensor 16, a second expansion valve (second pressure reduction unit) 17, and a second evaporator (second low-pressure side heat exchanger) 18. In the refrigerant circuit 10, the refrigerant RF circulates according to a refrigeration cycle.

[0017] When the heater mode or the heat pump mode is executed, the refrigerant circuit 10 is in a first circulation state in which the refrigerant RF circulates through the compressor 11, the condenser 12, the first expansion valve 13, the first evaporator 14, and the accumulator 15. On the other hand, when the cooling mode is executed, the refrigerant circuit 10 is in a second circulation state in which the refrigerant RF circulates through the compressor 11, the condenser 12, the second expansion valve 17, the second evaporator 18, and the accumulator 15.

[0018] A single refrigerant or a mixed refrigerant can be used as the refrigerant RF sealed in the refrigerant circuit 10. For example, HFC (hydrofluorocarbon) refrigerants such as R410A and R32, HFO (hydrofluoroolefin) refrigerants such as R1234ze and R1234yf, or hydrocarbon (HC) refrigerants such as propane and isobutane can be used. In particular, it is preferable to use R1234yf as the refrigerant in this embodiment.

[0019] When the above-listed fluorocarbon or hydrocarbon refrigerants are used, a subcritical refrigeration cycle is configured in which the refrigerant pressure on the high-pressure side does not exceed the critical pressure of the refrigerant. When carbon dioxide (CO2) is used as the refrigerant, a transcritical refrigeration cycle is configured in which the refrigerant pressure on the high-pressure side exceeds the critical pressure of the refrigerant. Even in this case, the refrigerant dissipates heat through the high-pressure side heat exchanger, as in the condenser 12 of this embodiment, and absorbs heat through the low-pressure side heat exchanger, as in the first evaporator 14 of this embodiment. Therefore, refrigerants that configure a transcritical refrigeration cycle, such as carbon dioxide refrigerant, can also be used in the refrigerant circuit 10.

[0020] The compressor 11 is, for example, an electric compressor equipped with an electric motor (not shown). The rotation speed of the compressor 11 is controlled by the control unit 30. The compressor 11 may be, for example, a scroll compressor or a rotary compressor.

[0021] The condenser 12 is a device that exchanges heat between the refrigerant RF discharged from the compressor 11 and the heat medium HM flowing through the heat medium circuit 20 .

[0022] The first expansion valve 13 reduces the pressure of the refrigerant RF flowing out from the condenser 12. As the first expansion valve 13, an electronic expansion valve whose opening degree can be controlled based on a command from the control unit 30, or a thermostatic expansion valve can be used. Note that a capillary tube may be used instead of the first expansion valve 13. Furthermore, a receiver (gas-liquid separator) (not shown) may be provided between the condenser 12 and the first expansion valve 13.

[0023] The first evaporator 14 is a device that exchanges heat between the refrigerant RF flowing out of the first expansion valve 13 and the heat medium HM flowing through the heat medium circuit 20. The refrigerant RF evaporated by the first evaporator 14 is guided to the suction side of the compressor 11.

[0024] The accumulator 15 stores the refrigerant RF guided from the first evaporator 14, separates the refrigerant RF into a gas phase and a liquid phase, and supplies the gas phase refrigerant RF to the compressor 11. The temperature sensor 16 detects the temperature of the refrigerant RF supplied from the first evaporator 14 to the accumulator 15.

[0025] The second expansion valve 17 reduces the pressure of the refrigerant RF flowing out from the condenser 12. As the second expansion valve 17, a thermostatic expansion valve or an electronic expansion valve whose opening degree can be controlled based on a command from the control unit 30 can be used. Note that a capillary tube may be used instead of the second expansion valve 17. Furthermore, a receiver (gas-liquid separator) (not shown) may be provided between the condenser 12 and the second expansion valve 17.

[0026] The compressor 11, condenser 12, first expansion valve 13, first evaporator 14, accumulator 15, temperature sensor 16, second expansion valve 17, and refrigerant piping connecting these elements are installed, for example, outside the passenger compartment.

[0027] <Configuration of Heat Medium Circuit 20> The heat medium circuit 20 is a circuit that circulates a heat medium HM that can transfer heat to and from the refrigerant RF via the condenser 12 and the first evaporator 14. The heat medium HM is used to cool or heat at least one temperature control target. In this embodiment, the temperature control target is air that is supplied to the vehicle interior for air conditioning. The temperature control target may also be an on-board battery device.

[0028] The heat medium HM sealed in the heat medium circuit 20 is a liquid such as water or brine that is maintained in a liquid phase and circulates through the heat medium circuit 20. Examples of the brine include a mixture of water and propylene glycol, or a mixture of water and ethylene glycol.

[0029] The heat medium circuit 20 includes a first pump 21, a second pump 22, an outdoor heat exchanger 23, a circulation flow path 24, an indoor air conditioning unit (temperature control device) 25, a three-way valve (flow path branching section) 26, a three-way valve (flow path switching section) 27, a three-way valve (flow path switching section) 28, a reserve tank 29, a flow path branching section B, and a flow path junction C.

[0030] The control unit 30 controls the start and stop and rotation speed of the first pump 21 and the second pump 22 .

[0031] The first pump 21 is disposed upstream of the three-way valve 26 in the flow direction of the heat medium HM and downstream of the flow path junction C in the flow direction, and is a device for pumping the heat medium HM along the flow direction. The first pump 21 is disposed between a first pump inlet pipe L2 connected to a condenser pipe (first heat medium flow path) L1 in which the condenser 12 is disposed, and an indoor air-conditioning heat exchanger inlet pipe L3. The flow path junction C is provided between the condenser pipe L1 and the first pump inlet pipe L2.

[0032] The second pump 22 is connected to a circulation flow path 24 that branches off from an evaporator pipe (second heat medium flow path) L5, in which the first evaporator 14 is disposed, at a flow path branch point B. The second pump 22 is a device that is disposed in the circulation flow path 24 and pressure-feeds the heat medium HM from the evaporator pipe L5 to the outdoor heat exchanger 23.

[0033] The exterior heat exchanger 23 is a device that exchanges heat between the heat medium HM and outside air outside the vehicle cabin. The exterior heat exchanger 23 is disposed, for example, near an air inlet of the vehicle. The outside air supplied to the exterior heat exchanger 23 by the vehicle running and the operation of the exterior heat exchanger fan 23a radiates or absorbs heat based on the temperature difference between the outside air and the heat medium HM. The temperature of the outside air supplied to the exterior heat exchanger 23 is detected by a temperature sensor 23b.

[0034] The circulation flow path 24 is a flow path that branches the heat medium HM from the evaporator piping L5 downstream of the first evaporator 14 in the flow direction of the heat medium HM and causes the heat medium HM to flow into the evaporator piping L5 at a three-way valve 27 upstream of the first evaporator 14 in the flow direction.

[0035] The interior air-conditioning unit 25 includes an interior air-conditioning fan 25 a, the second evaporator 18, an interior air-conditioning heat exchanger (temperature control device) 25 b, a damper 25 c, a temperature sensor 25 d, an outside air introduction flow path 25 e, an inside air introduction flow path 25 f, and a flow rate adjustment damper 25 g. The interior air-conditioning unit 25 provides conditioned air to the vehicle cabin by exchanging heat between the air sent by the interior air-conditioning fan 25 a and the refrigerant RF or the heat medium HM.

[0036] The second evaporator 18 cools the air sent by the indoor air-conditioning fan 25a through heat exchange with the refrigerant RF when the temperature adjustment system 100 is operating in the cooling mode. The indoor air-conditioning heat exchanger 25b heats the air (temperature adjustment target) sent by the indoor air-conditioning fan 25a through heat exchange with the heat medium HM when the temperature adjustment system 100 is operating in the heater mode or the heat pump mode.

[0037] The interior air-conditioning fan 25a is driven by an electric motor based on commands from the control unit 30, and blows air from inside the vehicle cabin (interior air), outside air, or a mixture of the interior air and outside air toward the second evaporator 18 and the interior air-conditioning heat exchanger 25b. When the temperature adjustment system 100 operates in a heater mode or a heat pump mode (described later), the damper 25c is positioned away from the interior air-conditioning heat exchanger 25b so that air blown from the interior air-conditioning fan 25a flows through the interior air-conditioning heat exchanger 25b.

[0038] The temperature sensor 25d detects the temperature of the interior air in the vehicle cabin, which is temperature-controlled by the interior air-conditioning fan 25a, and transmits the detected temperature to the control unit 30. The control unit 30 controls the temperature control system 100 so that the temperature detected by the temperature sensor 25d becomes a preset target temperature.

[0039] The outside air introduction passage 25e is a passage that introduces outside air Ae from outside the vehicle cabin to the second evaporator 18 and the interior air-conditioning heat exchanger 25b. The inside air introduction passage 25f is a passage that introduces inside air Ai from inside the vehicle cabin to the second evaporator 18 and the interior air-conditioning heat exchanger 25b.

[0040] The flow rate adjustment damper 25g adjusts a first flow rate of the outside air Ae guided from the outside air introduction passage 25e to the second evaporator 18 and the interior air-conditioning heat exchanger 25b, and a second flow rate of the inside air Ai guided from the inside air introduction passage 25f to the second evaporator 18 and the interior air-conditioning heat exchanger 25b. The flow rate adjustment damper 25g adjusts the first flow rate and the second flow rate based on a control command from the control unit 30.

[0041] As shown in FIG. 1, the second evaporator 18 is installed so that the outside air Ae introduced from the outside air introduction passage 25e passes through the upper side in the direction of gravity, and the inside air Ai introduced from the inside air introduction passage 25f passes through the lower side in the direction of gravity.

[0042] An indoor air-conditioning heat exchanger outlet pipe L6 is provided on the heat medium outlet side of the indoor air-conditioning heat exchanger 25b. The indoor air-conditioning heat exchanger outlet pipe L6 is connected to the three-way valve 26.

[0043] The three-way valve 26 is disposed downstream of the indoor air-conditioning heat exchanger 25b of the indoor air-conditioning unit 25 in the flow direction of the heat medium HM, and is a device that branches the heat medium HM to at least one of a condenser pipe L1 that leads to the condenser 12 and an evaporator pipe L5 that leads to the first evaporator 14. The three-way valve 26 is controlled by a control unit 30, and the connection direction of the three-way valve 26 is switched depending on the operation mode, and the flow rate of the heat medium HM that is led from the indoor air-conditioning heat exchanger outlet pipe L6 to the condenser pipe L1 and the flow rate of the heat medium HM that is led from the indoor air-conditioning heat exchanger outlet pipe L6 to the evaporator pipe L5 are adjusted.

[0044] The three-way valve 27 is a device that switches between a circulation state in which the heat medium HM flows through the circulation flow path 24 and a non-circulation state in which the heat medium HM does not flow through the circulation flow path 24. The three-way valve 27 is disposed in the circulation flow path 24 downstream of the outdoor heat exchanger 23 in the circulation direction and upstream of the first evaporator 14 in the circulation direction. The three-way valve 27 is controlled by the control unit 30, and can switch the connection direction or prevent the heat medium HM from flowing depending on the operation mode.

[0045] The three-way valve 28 is a device that switches between a circulation state in which the heat medium HM flows through the circulation flow path 24 and a non-circulation state in which the heat medium HM does not flow through the circulation flow path 24. The three-way valve 28 is disposed in the circulation flow path 24 downstream of the second pump 22 in the circulation direction and upstream of the outdoor heat exchanger 23 in the circulation direction. The three-way valve 28 is controlled by the control unit 30, and can switch the connection direction or prevent the heat medium HM from flowing depending on the operation mode.

[0046] The reserve tank 29 is a device that is arranged downstream of the flow path branch point B from the evaporator pipe L5 to the circulation flow path 24 in the flow direction of the heat medium HM and that stores the heat medium HM. When the heat medium HM sealed in the heat medium circuit 20 expands with an increase in temperature, the reserve tank 29 receives the heat medium HM in an amount that exceeds the capacity of the pipes of the heat medium circuit 20.

[0047] Furthermore, when the volume of the heat medium HM decreases with a drop in temperature, the heat medium HM is replenished from the reserve tank 29 to the evaporator pipe L5, so that the evaporator pipe L5 is kept filled with the heat medium HM. In other words, the reserve tank 29 can prevent the internal pressure of the evaporator pipe L5 from becoming excessively high or the pressure inside the evaporator pipe L5 from becoming negative. The interior of the reserve tank 29 is open to the atmosphere. The reserve tank 29 may be sealed and adjusted to a desired constant pressure.

[0048] The reserve tank 29 is preferably disposed in a portion of the evaporator pipe L5 extending from the flow path branching portion B to the flow path junction C, closer to the flow path junction C than the flow path branching portion B. This arrangement prevents the suction pressure of the first pump 21 from becoming negative, thereby preventing a negative pressure region from being formed in the heat medium circuit 20. The three-way valves 27 and 28 may be integrated valves using the same actuator. A flow path switching valve may be provided at the flow path junction C. The target to be temperature-controlled may be cooled by guiding the heat medium cooled in the first evaporator 14 to a temperature control device using a flow path switching valve (not shown).

[0049] The flow path branching portion B branches the heat medium HM flowing in from the evaporator pipe L5 toward either the flow path junction C or the second pump 22. The flow path junction C is disposed upstream of the indoor air-conditioning heat exchanger 25b in the flow direction of the heat medium HM, and merges the heat medium HM flowing in the condenser pipe L1 with the heat medium HM flowing from the evaporator pipe L5 via the flow path branching portion B.

[0050] <Configuration of control unit 30> The control unit 30 is a device that controls the refrigerant circuit 10 and the heat medium circuit 20. The control unit 30 is configured with, for example, a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in the storage medium or the like in the form of a program, for example, and the CPU reads this program into the RAM or the like and executes information processing and arithmetic processing to realize various functions.

[0051] Next, the control of the temperature adjustment system 100 configured as described above will be described. <Heater Mode: FIG. 1> The heater mode (temperature adjustment mode) is a mode suitable for heating when the outdoor air temperature is low and the outdoor heat exchanger 23 cannot absorb heat from the outdoor air to the heat medium HM. In the heater mode, the heat medium HM transports an amount of heat corresponding to the power of the compressor 11 as a heat source to the passenger compartment while avoiding heat radiation from the heat medium HM to the outdoor air. This ensures heating capacity even when the outdoor air temperature is significantly below 0°C. In the heat medium circuit 20 shown in FIG. 1, the areas where the heat medium HM flows are indicated by thick dashed lines, and the areas where the heat medium HM does not flow are indicated by thin dotted lines.

[0052] The refrigerant circuit 10 is started in response to a command from the control unit 30. As a result, the refrigerant RF is compressed by the compressor 11, and the high-temperature, high-pressure refrigerant RF is supplied to the condenser 12. In the condenser 12, the refrigerant RF exchanges heat with the heat medium HM, thereby releasing heat and condensing the refrigerant RF into a liquid. The liquefied high-pressure refrigerant RF is decompressed by the first expansion valve 13 and then supplied to the first evaporator 14.

[0053] In the first evaporator 14, the refrigerant RF exchanges heat with the heat medium HM to obtain latent heat of evaporation and evaporate, becoming low-pressure gaseous refrigerant RF. The refrigerant RF that has left the first evaporator 14 is guided to the compressor 11 and repeats the above-described refrigeration cycle. In the refrigerant circuit 10 shown in Figure 1, the areas where the refrigerant RF flows are indicated by thick solid lines, and the areas where the refrigerant RF does not flow are indicated by thin dotted lines.

[0054] The heat medium HM heated by the refrigerant RF in the condenser 12 is guided to the interior air-conditioning heat exchanger inlet pipe L3 through the condenser pipe L1 and the flow path junction C by the action of the first pump 21. The heat medium HM then provides heat to the air in the vehicle cabin (or outside air) guided from the interior air-conditioning fan 25a in the interior air-conditioning heat exchanger 25b, thereby heating the vehicle. The heat medium HM cooled by providing heat is guided to the three-way valve 26 through the interior air-conditioning heat exchanger outlet pipe L6.

[0055] The control unit 30 controls the three-way valve 26, the three-way valve 27, the three-way valve 28, and the first pump 21 to execute a heater mode in which the heat medium HM is branched into the condenser pipe L1 and the evaporator pipe L5 by the three-way valve 26, the heat medium HM branched into the evaporator pipe L5 by the three-way valve 27 and the three-way valve 28 is led from the evaporator pipe L5 to the flow path junction C via the flow path branching section B, and the heat medium HM that has passed through the condenser pipe L1 and the evaporator pipe L5 is joined at the flow path junction C and led to the indoor air conditioning unit 25.

[0056] The heat medium HM flowing to the condenser 12 absorbs heat from the refrigerant RF flowing through the condenser 12, causing the refrigerant RF to liquefy. The heat medium HM flowing to the first evaporator 14 imparts latent heat of evaporation to the refrigerant RF flowing through the first evaporator 14, causing the refrigerant RF to evaporate.

[0057] The three-way valve 26 is configured to adjust a first flow rate of the heat medium HM introduced to the condenser pipe L1 and a second flow rate of the heat medium HM introduced to the evaporator pipe L5. The control unit 30 controls the three-way valve 26 to adjust the first flow rate and the second flow rate, for example, based on the pressure and / or temperature of the refrigerant RF flowing into the first evaporator 14. The control unit 30 controls the three-way valve 26 to reduce the second flow rate when reducing the pressure of the refrigerant RF flowing into the first evaporator 14. The control unit 30 may reduce the flow rate of the heat medium HM flowing into the first evaporator 14 by, for example, reducing the rotation speed of the first pump 21.

[0058] Furthermore, the control unit 30 controls the three-way valve 26 to adjust the first flow rate and the second flow rate, for example, based on the pressure and / or temperature of the refrigerant RF flowing into the condenser 12. When the pressure of the refrigerant RF flowing into the condenser 12 is to be reduced, the control unit 30 controls the three-way valve 26 to increase the first flow rate. The control unit 30 may increase the flow rate of the heat medium HM flowing into the condenser 12, for example, by increasing the rotation speed of the first pump 21. Furthermore, the control unit 30 may control the rotation speed of the compressor 11 based on the temperature of the heat medium HM flowing into the indoor air-conditioning heat exchanger 25b.

[0059] Here, a control method when the temperature adjustment system 100 executes the heater mode will be described with reference to Fig. 2. Fig. 2 is a flowchart showing a control method when the temperature adjustment system 100 according to the first embodiment of the present disclosure executes the heater mode. Each process shown in Fig. 2 is a process for preventing a decrease in heating capacity when executing the heater mode and continuing continuous operation in the heater mode.

[0060] In step S101, the control unit 30 determines whether or not to execute the heater mode. If YES, the process proceeds to step S102, and if NO, the process of this flowchart ends.

[0061] In step S102, the control unit 30 controls the temperature adjustment system 100 to start the heater mode. The control unit 30 controls the temperature adjustment system 100 to set the refrigerant circuit 10 in the first circulation state, branch the heat medium HM into the condenser pipe L1 and the evaporator pipe L5 at the three-way valve 26, and merge the heat medium HM that has passed through the condenser pipe L1 and the evaporator pipe L5 at the flow path junction C and guide it to the indoor air-conditioning heat exchanger 25b.

[0062] In step S103, the control unit 30 determines whether the amount of refrigerant RF circulating through the compressor 11, the condenser 12, the first expansion valve 13, the first evaporator 14, and the accumulator 15 is insufficient, and if the determination is YES, the process proceeds to step S104, and if the determination is NO, the process proceeds to step S108.

[0063] In step S103, if the degree of superheat of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is greater than a first predetermined temperature, the control unit 30 determines that the amount of refrigerant RF in the second evaporator 18 is equal to or greater than a predetermined amount and that the amount of refrigerant RF circulating through the refrigerant circuit 10 in the first circulation state is insufficient. The control unit 30 acquires the temperature of the refrigerant RF supplied from the first evaporator 14 to the accumulator 15 from the temperature sensor 16, and determines whether the degree of superheat of the refrigerant RF is greater than the first predetermined temperature based on the acquired temperature.

[0064] 1 , the control unit 30 acquires the temperature of the refrigerant RF supplied from the first evaporator 14 to the accumulator 15 from the temperature sensor 16, but other configurations are also possible. For example, the control unit 30 may acquire the temperature of the refrigerant RF guided from the compressor 11 to the condenser 12 from another temperature sensor (not shown). In this case, when the degree of superheat of the refrigerant RF guided from the compressor 11 to the condenser 12 is greater than a second predetermined temperature, the control unit 30 determines that the amount of refrigerant RF in the second evaporator 18 is equal to or greater than a predetermined amount, and that the amount of refrigerant RF circulating through the refrigerant circuit 10 in the first circulation state is insufficient.

[0065] In step S104, the control unit 30 determines whether the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is greater than the saturation pressure Ps of the refrigerant RF corresponding to the temperature of the air passing through the second evaporator 18, and if the answer is YES, proceeds to step S105, and if the answer is NO, proceeds to step S108.

[0066] In step S104, the control unit 30 detects the temperature of the air passing through the second evaporator 18 using the temperature sensor, and calculates the saturation pressure Ps of the refrigerant RF corresponding to the temperature detected by the temperature sensor. The control unit 30 calculates the pressure of the refrigerant RF supplied from the first evaporator 14 to the accumulator 15 based on the temperature detected by the temperature sensor 16. The control unit 30 then determines whether the pressure of the refrigerant RF supplied from the first evaporator 14 to the accumulator 15 is greater than the saturation pressure Ps.

[0067] In step S105, the control unit 30 determines whether the temperature difference between the inside air temperature in the vehicle cabin detected by the temperature sensor 25d and the outside air temperature detected by the temperature sensor 23b is equal to or greater than a predetermined temperature; if the result is YES, the process proceeds to step S106; if the result is NO, the process proceeds to step S107.

[0068] In step S106, the control unit 30 controls the flow rate control damper 25g to increase the ratio of the second flow rate of the inside air Ai led from the inside air introduction flow path 25f to the second evaporator 18 and the heat exchanger 25b for indoor air conditioning to the first flow rate of the outside air Ae led from the outside air introduction flow path 25e to the second evaporator 18 and the heat exchanger 25b for indoor air conditioning, because the temperature of the inside air is higher than the temperature of the outside air by a predetermined temperature or more.

[0069] By increasing the second flow rate relative to the first flow rate, the temperature of the air passing through the second evaporator 18 increases, and the saturation pressure of the refrigerant RF in the second evaporator 18 increases. Therefore, it is possible to prevent a portion of the refrigerant RF guided from the first evaporator 14 to the accumulator 15 from flowing into the second evaporator 18.

[0070] In step S107, the control unit 30 controls the three-way valve 26 to increase the flow rate of the heat medium HM guided to the condenser pipe L1 and passing through the condenser 12, and to decrease the flow rate of the heat medium HM guided to the evaporator pipe L5 and passing through the first evaporator 14.

[0071] If the control unit 30 determines in step S104 that the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is greater than the saturation pressure Ps of the refrigerant RF corresponding to the temperature of the air passing through the second evaporator 18, it reduces the flow rate of the heat medium HM guided to the evaporator pipe L5 and passing through the first evaporator 14 in step S107.

[0072] Furthermore, if the temperature of the inside air is higher than the temperature of the outside air by a predetermined temperature or more, the control unit 30 further increases the ratio of the second flow rate of the inside air Ai to the first flow rate of the outside air Ae in step S106. By repeating the processes of steps S104 to S107, the control unit 30 controls the temperature adjustment system 100 so that the pressure of the refrigerant RF introduced from the first evaporator 14 to the compressor 11 is equal to or lower than the saturation pressure Ps corresponding to the temperature of the air passing through the second evaporator 18.

[0073] After executing step S107, the control unit 30 repeats the processing from step S103 onwards. When executing step S103 after executing step S107, if the degree of superheat of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is greater than a first predetermined temperature, the control unit 30 determines that the amount of refrigerant RF in the second evaporator 18 is equal to or greater than a predetermined amount, but other embodiments may be used. For example, when executing step S103 after executing step S107, the control unit 30 may determine NO if the degree of superheat of the refrigerant RF guided from the first evaporator 14 to the compressor 11 falls below a temperature that is even lower than the first predetermined temperature.

[0074] In step S108, the control unit 30 determines whether to end the heater mode, and if the determination is YES, the process proceeds to step S109, and if the determination is NO, the process proceeds to step S103. In step S109, the control unit 30 ends the heater mode and ends the process of this flowchart.

[0075] <Heat Pump Mode: FIG. 3> In the heat pump mode, heat is pumped from the outside air as a heat source to heat the vehicle interior. The operation of the refrigerant circuit 10 is the same as in the heater mode, so a description thereof will be omitted.

[0076] The heat medium HM heated by the refrigerant RF in the condenser 12 is guided to the interior air-conditioning heat exchanger inlet pipe L3 through the condenser pipe L1 by the action of the first pump 21. The heat medium HM then provides heat to the interior air Ai and / or the outside air Ae in the vehicle cabin guided from the interior air-conditioning fan 25a in the interior air-conditioning heat exchanger 25b, thereby heating the vehicle. The heat medium HM cooled by providing heat is guided to the three-way valve 26 through the interior air-conditioning heat exchanger outlet pipe L6.

[0077] The control unit 30 executes a heat pump mode in which the three-way valve 26 guides the heat medium HM from the indoor air-conditioning heat exchanger outlet pipe L6 to only the condenser pipe L1, and the three-way valve 28 guides the heat medium HM that has passed through the condenser pipe L1 to the indoor air-conditioning unit 25, thereby forming a first circulation system, and the three-way valves 27 and 28 guide the heat medium HM from the evaporator pipe L5 to the circulation flow path 24, thereby forming a second circulation system. The control unit 30 controls the three-way valves 26, 27, 28, the first pump 21, and the second pump 22 to execute the heat pump mode.

[0078] <Cooling Mode: FIG. 4> In the cooling mode, the interior air conditioning unit 25 supplies cool air to the vehicle interior.

[0079] The refrigerant circuit 10 is started in response to a command from the control unit 30. As a result, the refrigerant is compressed by the compressor 11, and the high-temperature, high-pressure refrigerant RF is supplied to the condenser 12. In the condenser 12, the refrigerant RF is condensed and liquefied by heat exchange with the heat medium HM. The liquefied high-pressure refrigerant RF is decompressed by the second expansion valve 17 and then supplied to the second evaporator 18. In the second evaporator 18, the refrigerant RF provides cold energy to the interior air Ai and / or the outside air Ae in the vehicle cabin, which are guided from the interior air-conditioning fan 25a. This cools the interior of the vehicle cabin to a desired temperature.

[0080] The heat medium HM heated by the refrigerant RF in the condenser 12 is guided to the indoor air-conditioning heat exchanger inlet pipe L3 through the condenser pipe L1 and the flow path junction C by the action of the first pump 21. The heat medium HM then passes through the indoor air-conditioning heat exchanger 25b and the outdoor heat exchanger 23 and is guided to the three-way valve 26. The heat medium HM guided to the circulation flow path 24 exchanges heat with outside air guided from the outdoor heat exchanger fan 23a in the outdoor heat exchanger 23 and dissipates heat. The heat medium HM cooled by dissipating heat passes through the three-way valve 26 and is guided to the condenser 12. In this way, in the cooling mode, the heat medium HM is circulated between the condenser 12 and the outdoor heat exchanger 23 by the first pump 21.

[0081] The temperature adjustment system 100 of the present embodiment described above has the following actions and effects. According to the temperature adjustment system 100 of the present embodiment, by executing the heater mode, the heat medium HM branches into the condenser pipe L1 and the evaporator pipe L5 at the three-way valve 26, which is located downstream in the flow direction of the heat medium HM from the indoor air-conditioning heat exchanger 25b that heats the air to be temperature-adjusted, and the heat medium HM that has passed through the condenser pipe L1 and the evaporator pipe L5 joins at the flow path junction C and is guided again to the indoor air-conditioning heat exchanger 25b that heats the air.

[0082] When the heater mode is executed, the refrigerant circuit 10 is in the first circulation state, so that the refrigerant RF is not guided to the second evaporator 18, and a portion of the refrigerant RF remains in the second evaporator 18. In this case, if the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 becomes higher than the saturation pressure Ps corresponding to the temperature of the air passing through the second evaporator 18, a portion of the refrigerant RF guided from the first evaporator 14 to the compressor 11 flows into the second evaporator 18, and the flow rate of the refrigerant RF drawn into the compressor 11 decreases.

[0083] Therefore, according to the temperature adjustment system 100 of this embodiment, in the heater mode, the control unit 30 controls the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 to be equal to or lower than the saturation pressure Ps corresponding to the temperature of the air passing through the second evaporator 18. Therefore, in the heater mode, a decrease in the flow rate of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is appropriately prevented. Therefore, a decrease in heating capacity when executing the heater mode in which the power of the compressor 11 is used to heat the temperature adjustment target can be prevented, and continuous operation of the heater mode can be continued.

[0084] According to the temperature control system 100 of this embodiment, the pressure of the refrigerant RF remaining in the second evaporator 18 is made higher than the pressure of the refrigerant RF led from the first evaporator 14 to the compressor 11, thereby preventing a portion of the refrigerant RF led from the first evaporator 14 to the compressor 11 from flowing into the second evaporator 18.

[0085] According to the temperature control system 100 of this embodiment, by passing the internal air Ai introduced from the internal air inlet passage 25f through the lower side of the second evaporator 18 in the direction of gravity, even if the liquefied refrigerant RF falls from above in the direction of gravity, the refrigerant RF can be reliably evaporated through heat exchange with the internal air Ai on the lower side in the direction of gravity.

[0086] According to the temperature adjustment system 100 of the present embodiment, by increasing the flow rate of the heat medium HM introduced into the condenser pipe L1 and decreasing the flow rate of the heat medium HM introduced into the evaporator pipe L5, it is possible to reduce the amount of heat input from the heat medium HM to the refrigerant RF in the first evaporator 14. This makes it possible to make the pressure of the refrigerant RF introduced from the first evaporator 14 to the compressor 11 equal to or lower than the pressure of the refrigerant RF remaining in the second evaporator 18, and to prevent a portion of the refrigerant RF introduced from the first evaporator 14 to the compressor 11 from flowing into the second evaporator 18.

[0087] According to the temperature control system 100 of this embodiment, in the heater mode, the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is set to be equal to or lower than the pressure of the refrigerant RF remaining in the second evaporator 18, thereby preventing a portion of the refrigerant RF guided from the first evaporator 14 to the compressor 11 from flowing into the second evaporator 18.

[0088] According to the temperature control system 100 of this embodiment, it is possible to appropriately determine whether the refrigerant RF in the second evaporator 18 is at or above a predetermined amount based on the degree of superheat of the refrigerant RF guided from the first evaporator 14 to the compressor 11.

[0089] According to the temperature adjustment system 100 of this embodiment, it is possible to appropriately determine whether the degree of superheat is greater than the first predetermined temperature based on the temperature of the refrigerant RF supplied from the first evaporator 14 to the accumulator 15.

[0090] Second Embodiment Next, a temperature adjustment system 100A according to a second embodiment of the present disclosure will be described with reference to the drawings. Fig. 5 is a schematic diagram showing the temperature adjustment system 100A according to the second embodiment of the present disclosure, illustrating a state in which the heater mode is being executed. This embodiment is a modification of the first embodiment, and is considered to be the same as the first embodiment except as otherwise specifically described below, and therefore further description will be omitted.

[0091] The temperature adjustment system 100 of the first embodiment was equipped with the accumulator 15 that stores the refrigerant RF guided from the first evaporator 14, separates the refrigerant RF into a gas phase and a liquid phase, and supplies the gas phase refrigerant RF to the compressor 11. In contrast, the temperature adjustment system 100 of the present embodiment is equipped with a receiver 12a in which the condenser 12 separates the refrigerant RF condensed by heat exchange with the heat medium HM into a gas phase and a liquid phase, and supplies the gas phase refrigerant RF to the first expansion valve 13.

[0092] In the first embodiment, in step S103 of FIG. 2 , if the degree of superheat of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is greater than a first predetermined temperature, the control unit 30 determines that the amount of refrigerant RF in the second evaporator 18 is equal to or greater than a predetermined amount, and that the amount of refrigerant RF circulating through the refrigerant circuit 10 in the first circulation state is insufficient.

[0093] On the other hand, in this embodiment, in step S103 of Figure 2, if the degree of subcooling of the refrigerant RF guided from the condenser 12 to the first expansion valve 13 is equal to or lower than a second predetermined temperature, the control unit 30 determines that the refrigerant RF in the second evaporator 18 is equal to or greater than a predetermined amount, and that the amount of refrigerant RF circulating through the refrigerant circuit 10 in the first circulation state is insufficient.

[0094] In this embodiment, the control unit 30 repeats the processing from step S103 onward after executing step S107 in Fig. 2. When executing step S103 after executing step S107, the control unit 30 determines that the amount of refrigerant RF in the second evaporator 18 is equal to or greater than a predetermined amount if the degree of subcooling of the refrigerant RF guided from the condenser 12 to the first expansion valve 13 is equal to or less than a second predetermined temperature, but other aspects may be used. For example, when executing step S103 after executing step S107, the control unit 30 may determine NO if the degree of subcooling of the refrigerant RF guided from the condenser 12 to the first expansion valve 13 is equal to or greater than a temperature that is even higher than the second predetermined temperature.

[0095] According to the temperature control system 100A of this embodiment, it is possible to appropriately determine whether the refrigerant RF in the second evaporator 18 is at or above a predetermined amount based on the degree of subcooling of the refrigerant led from the condenser 12 to the first expansion valve 13.

[0096] [Other Embodiments] In the above description, when the temperature adjustment system 100 executes the heater mode, if it is determined in step S104 that the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is greater than the saturation pressure Ps of the refrigerant RF corresponding to the temperature of the air passing through the second evaporator 18, the flow rate of the heat medium HM guided to the evaporator pipe L5 and passing through the first evaporator 14 is reduced in step S107. However, other embodiments may be used.

[0097] For example, a bypass pipe (not shown) that connects the upstream side and downstream side of the first evaporator 14 in the evaporator pipe L5 and a switching valve (not shown) that switches between a state in which the heat medium HM flows through the bypass pipe and a state in which the heat medium HM does not flow through the bypass pipe may be provided. In this case, when executing the heater mode, if the control unit 30 determines in step S104 that the pressure of the refrigerant RF guided from the first evaporator 14 to the compressor 11 is higher than the saturation pressure Ps of the refrigerant RF that corresponds to the temperature of the air passing through the second evaporator 18, the control unit 30 controls the switching valve to allow the heat medium HM to flow through the bypass pipe and not to allow the heat medium HM to flow through the first evaporator 14.

[0098] The temperature regulation system and the control method for the temperature regulation system described in each of the above-described embodiments can be understood, for example, as follows.

[0099] A temperature adjustment system according to a first aspect of the present disclosure includes a refrigerant circuit (10) having a first circulation state in which a refrigerant circulates through a compressor (11), a high-pressure side heat exchanger (12), a first pressure reduction section (13), and a first low-pressure side heat exchanger (14), and a second circulation state in which the refrigerant circulates through the compressor, a second pressure reduction section (17), and a second low-pressure side heat exchanger (18); a heat medium circuit (20) that circulates a heat medium that exchanges heat with the refrigerant through the high-pressure side heat exchanger and the first low-pressure side heat exchanger; and a control unit (30) that controls the refrigerant circuit and the heat medium circuit, and a temperature control device (25b) that heats a temperature control target using a body, and the high-pressure side heat exchanger and the first low-pressure side heat exchanger can be set to be in series with the temperature control device, and the control unit can set the refrigerant circuit to the first circulation state and execute a temperature control mode for the temperature control device in which the high-pressure side heat exchanger and the first low-pressure side heat exchanger are circuited in series, and in the temperature control mode, controls the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor to be equal to or lower than a saturation pressure corresponding to the temperature of air passing through the second low-pressure side heat exchanger.

[0100] In the temperature adjustment system according to the first aspect of the present disclosure, when the temperature adjustment mode is executed, the refrigerant circuit is in the first circulation state, so that no refrigerant is guided to the second low-pressure heat exchanger, and some refrigerant remains in the second low-pressure heat exchanger. In this case, if the pressure of the refrigerant guided from the first low-pressure heat exchanger to the compressor becomes higher than the saturation pressure corresponding to the temperature of the air passing through the second low-pressure heat exchanger, some of the refrigerant guided from the first low-pressure heat exchanger to the compressor will flow into the second low-pressure heat exchanger, reducing the flow rate of the refrigerant drawn into the compressor.

[0101] Therefore, in the temperature control system according to the first aspect of the present disclosure, the control unit controls the pressure of the refrigerant guided from the first low-pressure heat exchanger to the compressor so that it is equal to or lower than the saturation pressure corresponding to the temperature of the air passing through the second low-pressure heat exchanger in the temperature control mode. This appropriately prevents a decrease in the flow rate of the refrigerant guided from the first low-pressure heat exchanger to the compressor in the temperature control mode. This prevents a decrease in heating capacity when executing the temperature control mode, which uses the power of the compressor to heat the temperature control target, and allows continuous operation in the temperature control mode to be continued.

[0102] A temperature adjustment system according to a second aspect of the present disclosure is the first aspect, further comprising the following configuration: an outside air introduction passage (25e) that introduces outside air from outside the vehicle cabin to the second low-pressure side heat exchanger, an inside air introduction passage (25f) that introduces inside air from inside the vehicle cabin to the second low-pressure side heat exchanger, and a flow rate adjustment unit (25g) that adjusts a first flow rate of the outside air introduced from the outside air introduction passage to the second low-pressure side heat exchanger and a second flow rate of the inside air introduced from the inside air introduction passage to the second low-pressure side heat exchanger, wherein in the temperature adjustment mode, when the pressure of the refrigerant introduced from the first low-pressure side heat exchanger to the compressor is higher than a saturation pressure corresponding to a temperature of air passing through the second low-pressure side heat exchanger, the control unit controls the flow rate adjustment unit to decrease the first flow rate and increase the second flow rate.

[0103] According to the temperature control system of the second aspect of the present disclosure, the pressure of the refrigerant remaining in the second low-pressure side heat exchanger is made higher than the pressure of the refrigerant led from the first low-pressure side heat exchanger to the compressor, thereby preventing a portion of the refrigerant led from the first low-pressure side heat exchanger to the compressor from flowing into the second low-pressure side heat exchanger.

[0104] The temperature adjustment system according to the third aspect of the present disclosure is the second aspect, and further includes the following configuration: That is, the second low-pressure side heat exchanger is installed so that outside air introduced from the outside air introduction passage passes through an upper side in the direction of gravity, and inside air introduced from the inside air introduction passage passes through a lower side in the direction of gravity.

[0105] According to the temperature control system of the third aspect of the present disclosure, by passing the internal air introduced from the internal air inlet passage through the lower side in the direction of gravity of the second low-pressure side heat exchanger, even if the liquefied refrigerant falls from above in the direction of gravity, the refrigerant can be reliably evaporated through heat exchange with the internal air on the lower side in the direction of gravity.

[0106] A temperature adjustment system according to a fourth aspect of the present disclosure is the first aspect, further including the following configuration: In other words, in the temperature adjustment mode, the control unit has a flow path branching unit capable of adjusting the flow rate of the heat medium guided to the first low-pressure side heat exchanger, and when the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor is higher than a saturation pressure corresponding to a temperature of air passing through the second low-pressure side heat exchanger, controls the flow path branching unit to reduce the flow rate of the heat medium guided to the first low-pressure side heat exchanger.

[0107] According to the temperature control system of the fourth aspect of the present disclosure, the amount of heat input from the heat medium to the refrigerant in the first low-pressure heat exchanger can be reduced by reducing the flow rate of the heat medium introduced into the first low-pressure heat exchanger, thereby making the pressure of the refrigerant introduced from the first low-pressure heat exchanger to be equal to or lower than the pressure of the refrigerant remaining in the second low-pressure heat exchanger, and preventing a portion of the refrigerant introduced from the first low-pressure heat exchanger to the compressor from flowing into the second low-pressure heat exchanger.

[0108] A temperature adjustment system according to a fifth aspect of the present disclosure is the temperature adjustment system of any one of the first to fourth aspects, further including the following configuration: That is, in the temperature adjustment mode, when the refrigerant in the second low-pressure side heat exchanger is equal to or greater than a predetermined amount, the control unit controls the pressure of the refrigerant guided from the first low-pressure side heat exchanger to be equal to or less than a saturation pressure corresponding to the temperature of air passing through the second low-pressure side heat exchanger.

[0109] According to the temperature control system of the fifth aspect of the present disclosure, in the temperature control mode, the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor is set to be equal to or lower than the pressure of the refrigerant remaining in the second low-pressure side heat exchanger, thereby preventing a portion of the refrigerant guided from the first low-pressure side heat exchanger to the compressor from flowing into the second low-pressure side heat exchanger.

[0110] A temperature adjustment system according to a sixth aspect of the present disclosure is the fifth aspect, further including the following configuration: That is, when the degree of superheat of the refrigerant guided from the first low-pressure side heat exchanger to the compressor is greater than a first predetermined temperature, the control unit determines that the refrigerant in the second low-pressure side heat exchanger is equal to or greater than the predetermined amount.

[0111] According to the temperature control system of the sixth aspect of the present disclosure, it is possible to appropriately determine whether the amount of refrigerant in the second low-pressure side heat exchanger is greater than or equal to a predetermined amount based on the degree of superheat of the refrigerant led from the first low-pressure side heat exchanger to the compressor.

[0112] A temperature adjustment system according to a seventh aspect of the present disclosure is the sixth aspect, further including the following configuration: the refrigerant circuit includes an accumulator (15) that stores the refrigerant guided from the first low-pressure side heat exchanger and supplies the refrigerant to the compressor, and a temperature detection unit (16) that detects the temperature of the refrigerant supplied from the first low-pressure side heat exchanger to the accumulator, and the control unit determines whether the degree of superheat of the refrigerant guided from the first low-pressure side heat exchanger to the compressor is greater than the first predetermined temperature based on the temperature of the refrigerant detected by the temperature detection unit.

[0113] According to the temperature control system of the seventh aspect of the present disclosure, it is possible to appropriately determine whether the degree of superheat is greater than the first predetermined temperature based on the temperature of the refrigerant supplied from the first low-pressure side heat exchanger to the accumulator.

[0114] A temperature adjustment system according to an eighth aspect of the present disclosure is the fifth aspect, further including the following configuration: That is, the control unit determines that the amount of the refrigerant in the second low-pressure side heat exchanger is equal to or greater than the predetermined amount when the degree of subcooling of the refrigerant guided from the high-pressure side heat exchanger to the first decompression unit is equal to or less than a second predetermined temperature.

[0115] According to the temperature control system of the eighth aspect of the present disclosure, it is possible to appropriately determine whether the amount of refrigerant in the second low-pressure side heat exchanger is greater than or equal to a predetermined amount based on the degree of subcooling of the refrigerant led from the first high-pressure side heat exchanger to the first pressure reduction section.

[0116] In a control method for a temperature adjustment system according to a ninth aspect of the present disclosure, the temperature adjustment system includes a refrigerant circuit having a first circulation state in which a refrigerant circulates through a compressor, a high-pressure side heat exchanger, a first decompression unit, and a first low-pressure side heat exchanger, and a second circulation state in which the refrigerant circulates through the compressor, a second decompression unit, and a second low-pressure side heat exchanger, and a heat medium circuit that circulates a heat medium that exchanges heat with the refrigerant through the high-pressure side heat exchanger and the first low-pressure side heat exchanger, and the heat medium circuit has a temperature adjustment device that heats a temperature adjustment target using the heat medium. The high-pressure side heat exchanger and the first low-pressure side heat exchanger can be set so as to be in series with the temperature adjustment device, and a control process is provided in which the refrigerant circuit is set to the first circulation state and a temperature adjustment mode is executed in which the high-pressure side heat exchanger and the first low-pressure side heat exchanger are circuited in series with the temperature adjustment device, and the control process controls the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor so that it is equal to or lower than a saturation pressure corresponding to the temperature of air passing through the second low-pressure side heat exchanger in the temperature adjustment mode.

[0117] According to the control method for a temperature adjustment system according to the ninth aspect of the present disclosure, when the temperature adjustment mode is executed, the refrigerant circuit is in the first circulation state, so that no refrigerant is guided to the second low-pressure heat exchanger, and some refrigerant remains in the second low-pressure heat exchanger. In this case, if the pressure of the refrigerant guided from the first low-pressure heat exchanger to the compressor becomes higher than the saturation pressure corresponding to the temperature of the air passing through the second low-pressure heat exchanger, some of the refrigerant guided from the first low-pressure heat exchanger to the compressor will flow into the second low-pressure heat exchanger, reducing the flow rate of refrigerant drawn into the compressor.

[0118] According to a control method for a temperature control system according to a ninth aspect of the present disclosure, the control step controls the pressure of the refrigerant guided from the first low-pressure heat exchanger to the compressor in the temperature control mode so that it is equal to or lower than the saturation pressure corresponding to the temperature of the air passing through the second low-pressure heat exchanger. This appropriately prevents a decrease in the flow rate of the refrigerant guided from the first low-pressure heat exchanger to the compressor in the temperature control mode. This prevents a decrease in heating capacity when executing the temperature control mode, which uses the power of the compressor to heat the temperature control target, and allows continuous operation of the temperature control mode to be continued.

[0119] 10 Refrigerant circuit 11 Compressor 12 Condenser (high-pressure side heat exchanger) 12a Receiver 13 First expansion valve (first decompression section) 14 First evaporator (first low-pressure side heat exchanger) 15 Accumulator 16 Temperature sensor 17 Second expansion valve (second decompression section) 18 Second evaporator (second low-pressure side heat exchanger) 20 Heat medium circuit 21 First pump 22 Second pump 23 Outdoor heat exchanger 23a Outdoor heat exchanger fan 23b Temperature sensor 24 Circulation flow path 25 Indoor air conditioning unit 25a Indoor air conditioning fan 25b Indoor air conditioning heat exchanger (temperature control device) 25c Damper 25d Temperature sensor 25e Outside air introduction flow path 25f Inside air introduction flow path 25g Flow rate adjustment damper (flow rate adjustment section) 26 Three-way valve (flow path branching section) 27, 28 Three-way valves 29 Reservoir tank 30 Control unit 100, 100A Temperature control system Ae Outside air Ai Inside air B Flow path branching section C Flow path merging section HM Heat medium L1 Condenser pipe (first heat medium flow path) L2 First pump inlet pipe L3 Indoor air conditioning heat exchanger inlet pipe L5 Evaporator pipe (second heat medium flow path) L6 Indoor air conditioning heat exchanger outlet pipe RF Refrigerant

Claims

1. A system comprising: a refrigerant circuit having a first circulation state in which a refrigerant circulates through a compressor, a high-pressure side heat exchanger, a first pressure reducing section, and a first low-pressure side heat exchanger, and a second circulation state in which the refrigerant circulates through the compressor, a second pressure reducing section, and a second low-pressure side heat exchanger; a heat medium circuit that circulates a heat medium that exchanges heat with the refrigerant through the high-pressure side heat exchanger and the first low-pressure side heat exchanger; and a control unit that controls the refrigerant circuit and the heat medium circuit, wherein the heat medium circuit has a temperature control device that heats a temperature control target using the heat medium, and the high-pressure side heat exchanger and the first low-pressure side heat exchanger can be set to be in series with the temperature control device, and the control unit is capable of setting the refrigerant circuit in the first circulation state and executing a temperature control mode in which the high-pressure side heat exchanger and the first low-pressure side heat exchanger are circuited in series with the temperature control device, In the temperature control mode, the temperature control system controls the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor so that it is equal to or lower than a saturation pressure corresponding to the temperature of the air passing through the second low-pressure side heat exchanger.

2. A temperature control system as described in claim 1, comprising: an outside air intake passage that introduces outside air from outside the vehicle cabin to the second low-pressure side heat exchanger; an inside air intake passage that introduces inside air from inside the vehicle cabin to the second low-pressure side heat exchanger; and a flow rate adjustment unit that adjusts a first flow rate of outside air guided from the outside air intake passage to the second low-pressure side heat exchanger and a second flow rate of inside air guided from the inside air intake passage to the second low-pressure side heat exchanger, wherein in the temperature control mode, when the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor is higher than a saturation pressure corresponding to the temperature of the air passing through the second low-pressure side heat exchanger, the control unit controls the flow rate adjustment unit to decrease the first flow rate and increase the second flow rate.

3. The temperature control system of claim 2, wherein the second low-pressure side heat exchanger is installed so that outside air introduced from the outside air introduction flow path passes through on the upper side in the direction of gravity, and inside air introduced from the inside air introduction flow path passes through on the lower side in the direction of gravity.

4. The temperature control system of claim 1, wherein the control unit has a flow path branching section that can adjust the flow rate of the heat medium led to the first low-pressure side heat exchanger in the temperature control mode, and controls the flow path branching section to reduce the flow rate of the heat medium led to the first low-pressure side heat exchanger when the pressure of the refrigerant led from the first low-pressure side heat exchanger to the compressor is greater than the saturation pressure corresponding to the temperature of the air passing through the second low-pressure side heat exchanger.

5. A temperature control system as described in any one of claims 1 to 4, wherein, in the temperature control mode, when the refrigerant in the second low-pressure side heat exchanger is at or above a predetermined amount, the control unit controls the pressure of the refrigerant led from the first low-pressure side heat exchanger to the compressor so that it is below a saturation pressure corresponding to the temperature of the air passing through the second low-pressure side heat exchanger.

6. A temperature control system as described in claim 5, wherein the control unit determines that the amount of refrigerant in the second low-pressure side heat exchanger is equal to or greater than the predetermined amount when the degree of superheat of the refrigerant led from the first low-pressure side heat exchanger to the compressor is greater than a first predetermined temperature.

7. The temperature control system described in claim 6, wherein the refrigerant circuit has an accumulator that stores the refrigerant led from the first low-pressure side heat exchanger and supplies it to the compressor, and a temperature detection unit that detects the temperature of the refrigerant supplied from the first low-pressure side heat exchanger to the accumulator, and the control unit determines whether the degree of superheat of the refrigerant led from the first low-pressure side heat exchanger to the compressor is greater than the first predetermined temperature based on the temperature of the refrigerant detected by the temperature detection unit.

8. A temperature control system as described in claim 5, wherein the control unit determines that the amount of refrigerant in the second low-pressure side heat exchanger is equal to or greater than the predetermined amount when the degree of subcooling of the refrigerant led from the high-pressure side heat exchanger to the first pressure reducing unit is equal to or less than a second predetermined temperature.

9. A control method for a temperature control system, wherein the temperature control system comprises: a refrigerant circuit having a first circulation state in which a refrigerant circulates through a compressor, a high-pressure side heat exchanger, a first pressure reducing section, and a first low-pressure side heat exchanger; and a heat medium circuit that circulates a heat medium that exchanges heat with the refrigerant through the high-pressure side heat exchanger and the first low-pressure side heat exchanger, wherein the heat medium circuit has a temperature control device that uses the heat medium to heat a temperature control target, and the high-pressure side heat exchanger and the first low-pressure side heat exchanger can be set to be in series with the temperature control device, and the control method comprises a control step of setting the refrigerant circuit in the first circulation state and executing a temperature control mode in which the high-pressure side heat exchanger and the first low-pressure side heat exchanger are circuited in series with the temperature control device, The control process is a control method for a temperature control system in which, in the temperature control mode, the pressure of the refrigerant guided from the first low-pressure side heat exchanger to the compressor is controlled to be equal to or lower than a saturation pressure corresponding to the temperature of the air passing through the second low-pressure side heat exchanger.

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