Temperature control system and its control method

Abstract

This system provides a temperature control system that can minimize the decrease in heating capacity when switching from heat pump mode to heater mode. [Solution] The heat transfer medium circuit includes an indoor heat exchanger 18 that exchanges heat between hot water and indoor air, and an outdoor heat exchanger 22 that exchanges heat between chilled water and outside air. The control unit has a heat pump mode in which hot water discharged from the condenser 11 is guided to the indoor heat exchanger 18 and chilled water discharged from the evaporator 13 is guided to the outdoor heat exchanger 22; a heater mode in which at least a portion of the hot water discharged from the condenser 11 and chilled water discharged from the evaporator 13 are mixed, at least a portion of the heat transfer medium discharged from the condenser 11 is guided to the indoor heat exchanger 18, and the mixed chilled and hot water is guided to the condenser 11 and the evaporator 13; and a first transition mode in which, before switching from the heat pump mode to the heater mode, the hot water flowing through the indoor heat exchanger 18 is mixed with the chilled water flowing through the outdoor heat exchanger 22.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a temperature control system for a vehicle having a heat pump mode and a heater mode. In the heat pump mode, heat is absorbed from the outside air by an outdoor heat exchanger, and heating is performed by an indoor heat exchanger. The heater mode is a mode in which heating is performed using a compressor as a heat source when the outside air temperature drops and the amount of heat absorbed from the outside air decreases, making it difficult to perform heating in the heat pump mode. In the heater mode, the cold water cooled by the evaporator is mixed with the warm water heated by the condenser and led to the indoor heat exchanger for heating, and the warm water that has exchanged heat in the indoor heat exchanger is returned to the condenser and the evaporator.

[0003] Patent Document 1 discloses switching from the heat pump mode to the heater mode based on the outside air temperature.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a result of intensive studies by the present inventors, the following problems have been found when switching from the heat pump mode to the heater mode. That is, when switching to the heater mode, the cold water cooled by the evaporator is mixed with the warm water heated by the condenser, so the temperature of the warm water flowing into the indoor heat exchanger temporarily drops. As a result, there is a risk that the heating capacity (heating ability) will decrease immediately after switching to the heater mode.

[0006] This disclosure is made in view of these circumstances and aims to provide a temperature control system and a control method thereof that can suppress as much as possible the decrease in heating capacity when switching from heat pump mode to heater mode. [Means for solving the problem]

[0007] A temperature control system according to one aspect of the present disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; a heat transfer medium circuit through which a heat transfer medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates; and a control unit for controlling the refrigerant circuit and the heat transfer medium circuit, wherein the heat transfer medium circuit comprises a temperature control device that exchanges heat between the heat transfer medium and a temperature control target, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and outside air, and the control unit controls the heat transfer medium that has flowed out from the high-pressure side heat exchanger. The system includes a heat pump mode in which the body is guided to the temperature control equipment and the heat transfer medium flowing out of the low-pressure heat exchanger is guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium flowing out of the high-pressure heat exchanger and at least a portion of the heat transfer medium flowing out of the low-pressure heat exchanger are mixed and at least a portion of the heat transfer medium flowing out of the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a first transition mode in which, before switching from the heat pump mode to the heater mode, the heat transfer medium flowing through the temperature control equipment is mixed with the heat transfer medium flowing through the outdoor heat exchanger.

[0008] A temperature control system according to one aspect of the present disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; a heat transfer medium circuit through which a heat transfer medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates; and a control unit for controlling the refrigerant circuit and the heat transfer medium circuit, wherein the heat transfer medium circuit comprises a temperature control device that exchanges heat between the heat transfer medium and a temperature-controlled object, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and outside air, and the control unit flows out from the high-pressure side heat exchanger. The system includes a heat pump mode in which the prepared heat transfer medium is guided to the temperature control equipment and the heat transfer medium discharged from the low-pressure heat exchanger is guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium discharged from the high-pressure heat exchanger and at least a portion of the heat transfer medium discharged from the low-pressure heat exchanger are mixed and at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a second transition mode in which a portion of the heat transfer medium flowing from the temperature control equipment to the high-pressure heat exchanger is mixed with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure heat exchanger.

[0009] A control method for a temperature control system according to one aspect of the present disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; and a heat medium circuit through which a heat medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates, wherein the heat medium circuit comprises a temperature control device for exchanging heat between the heat medium and a temperature control target, and an outdoor heat exchanger for exchanging heat between the heat medium and the outside air, and the control method for a temperature control system comprising the heat medium flowing out from the high-pressure side heat exchanger The system includes a heat pump mode in which the heat transfer medium is guided to the equipment and the heat transfer medium discharged from the low-pressure heat exchanger is guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium discharged from the high-pressure heat exchanger and at least a portion of the heat transfer medium discharged from the low-pressure heat exchanger are mixed, at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger is guided to the temperature control equipment, and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a first transition mode in which, before switching from the heat pump mode to the heater mode, the heat transfer medium circulating in the temperature control equipment is mixed with the heat transfer medium circulating in the outdoor heat exchanger.

[0010] A control method for a temperature control system according to one aspect of the present disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; and a heat transfer medium circuit through which a heat transfer medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates, wherein the heat transfer medium circuit comprises a temperature control device that exchanges heat between the heat transfer medium and a temperature control target, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and outside air, wherein the heat transfer medium that has flowed out from the high-pressure side heat exchanger The system includes a heat pump mode in which the heat transfer medium flowing from the low-pressure heat exchanger is guided to the temperature control equipment and also guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium flowing from the high-pressure heat exchanger and at least a portion of the heat transfer medium flowing from the low-pressure heat exchanger are mixed, at least a portion of the heat transfer medium flowing from the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a second transition mode in which a portion of the heat transfer medium flowing from the temperature control equipment to the high-pressure heat exchanger is mixed with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure heat exchanger. [Effects of the Invention]

[0011] This minimizes the decrease in heating capacity when switching from heat pump mode to heater mode. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a vehicle air conditioning system according to the first embodiment of this disclosure, specifically illustrating the heat pump mode. [Figure 2] Figure 1 is a schematic diagram showing the first transition mode of the vehicle air conditioning system. [Figure 3] Figure 1 is a schematic diagram showing the second transition mode of the vehicle air conditioning system. [Figure 4] Figure 1 is a schematic diagram showing the heater mode of the vehicle air conditioning system. [Figure 5] This is a flowchart showing the transitions between each operating mode. [Figure 6] It is a flowchart showing a modified example of FIG. 5. [Figure 7] It is a schematic configuration diagram showing the heat pump mode of the vehicle air conditioner according to the second embodiment of the present disclosure. [Figure 8] It is a schematic configuration diagram showing the first transition mode of the vehicle air conditioner of FIG. 7. [Figure 9] It is a schematic configuration diagram showing a modified example of FIG. 8. [Figure 10] It is a schematic configuration diagram showing the second transition mode of the vehicle air conditioner of FIG. 7. [Figure 11] It is a schematic configuration diagram showing a modified example of FIG. 10. [Figure 12] It is a schematic configuration diagram showing the heater mode of the vehicle air conditioner of FIG. 7. [Figure 13] It is a schematic configuration diagram showing a modified example of FIG. 12.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. [First Embodiment] Hereinafter, the first embodiment of the present disclosure will be described with reference to FIG. 1. FIG. 1 shows an outline of a vehicle air conditioner (temperature control system) 1 according to the present embodiment. The vehicle air conditioner 1 includes a refrigerant circuit 3, a hot water circuit (heat medium circuit) 5, and a cold water circuit (heat medium circuit) 7.

[0014] The refrigerant circuit 3 includes a compressor 10 that compresses a refrigerant, a condenser (high-pressure side heat exchanger) 11 that condenses (or releases heat) the refrigerant compressed by the compressor 10, an expansion valve 12 that expands the refrigerant condensed by the condenser 11, and an evaporator (low-pressure side heat exchanger) 13 that evaporates the refrigerant expanded by the expansion valve 12, and constitutes a refrigeration cycle. As the compressor 10, for example, a scroll compressor or a rotary compressor is used. The operation of the refrigerant circuit 3 is controlled by a control unit not shown.

[0015] The hot water circuit 5 mainly supplies the hot water (heat medium, coolant) heated by the condenser 11 to the indoor heat exchanger (temperature control device) 18, and is a flow path for returning the hot water flowing out from the indoor heat exchanger 18 to the condenser 11.

[0016] In the hot water circuit 5, a first four-way valve 20 is connected to a hot water outlet pipe 19 from which hot water flows out of the condenser 11. To the first four-way valve 20, a cold water outlet pipe 21 from which cold water flows out of the evaporator 13 in the cold water circuit 7, an outdoor heat exchange inlet pipe 24 provided on the upstream side of the outdoor heat exchanger 22, and an outdoor heat exchange bypass pipe 26 that bypasses the outdoor heat exchanger 22 are connected. The connection direction of the first four-way valve 20 is controlled by the control unit.

[0017] The outdoor heat exchanger 22 exchanges heat between a heat medium such as water and outside air (fluid). A second four-way valve 28 is connected to an outdoor heat exchange outlet pipe 27 from which the heat medium flows out of the outdoor heat exchanger 22. The outdoor heat exchange bypass pipe 26 is connected to the second four-way valve 28. That is, the outdoor heat exchange bypass pipe 26 connects the first four-way valve 20 and the second four-way valve 28.

[0018] To the second four-way valve 28, a hot water pump inlet pipe 31 connected to the inlet side of the hot water pump 30 and a cold water pump inlet pipe 33 connected to the inlet side of the cold water pump 32 are connected. The connection direction of the second four-way valve 28 is controlled by the control unit. The rotational speed, that is, the flow rate, of the hot water pump 30 and the cold water pump 32 is controlled by the control unit.

[0019] A hot water discharge pipe 35 from which hot water is discharged from the hot water pump 30 is connected to a third four-way valve 37. A cold water discharge pipe 36 from which cold water is discharged from the cold water pump 32 is connected to the third four-way valve 37. To the third four-way valve 37, a four-way valve connection pipe 40 connected to the fourth four-way valve 39 and an indoor heat exchange inlet pipe 41 connected to the inlet side of the indoor heat exchanger 18 are connected. The connection directions of the third four-way valve 37 and the fourth four-way valve 39 are controlled by the control unit.

[0020] The indoor heat exchanger outlet pipe 42, which is connected to the outlet side of the indoor heat exchanger 18, is connected to the fourth four-way valve 39. The fourth four-way valve 39 is connected to the hot water return pipe 44, which returns hot water to the condenser 11, and the chilled water return pipe 45, which returns chilled water to the evaporator 13.

[0021] A heat transfer medium bypass pipe 47 is provided between the hot water pump inlet pipe 31 upstream of the hot water pump 30 and the chilled water pump inlet pipe 33 upstream of the chilled water pump 32. Hot water flows from the hot water circuit 5 to the chilled water circuit 7, or chilled water flows from the chilled water circuit 7 to the hot water circuit 5, through the heat transfer medium bypass pipe 47. A reserve tank 48 for storing hot water or chilled water is provided in the heat transfer medium bypass pipe 47.

[0022] The control unit consists of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in ROM or other storage media, provided stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory.

[0023] Next, the operation of each operating mode using the vehicle air conditioning system 1 with the above configuration will be explained. <Heat pump mode> Figure 1 shows the heat pump mode. The heat pump mode is used for heating when the outside air temperature is low, such as in winter. In heat pump mode, the outdoor heat exchanger 22 absorbs heat from the outside air, and the indoor heat exchanger 18 heats the indoor air.

[0024] In the hot water circuit 5 and the chilled water circuit 7 (heat transfer fluid circuit), a dashed line indicates the flow of chilled water, a dotted line indicates the flow of hot water, and a solid line indicates the absence of heat transfer fluid (the same applies to the following figures).

[0025] In the refrigerant circuit 3, the refrigerant compressed by the compressor 10 is sent to the condenser 11 where it condenses. As the refrigerant condenses, the latent heat of condensation is transferred to the hot water, which is the heat transfer medium flowing through the condenser 11, causing it to heat up.

[0026] The liquid refrigerant exiting the condenser 11 is depressurized by the expansion valve 12 and guided to the evaporator 13. In the evaporator 13, the refrigerant evaporates, and the latent heat of vaporization is absorbed from the chilled water, which is the heat transfer medium circulating in the evaporator 13, thereby cooling the chilled water.

[0027] After being heated in the condenser 11, the hot water passes through the hot water outlet pipe 19, the first four-way valve 20, the outdoor heat exchanger bypass pipe 26, the second four-way valve 28, the hot water pump inlet pipe 31, the hot water pump 30, the third four-way valve 37, and the indoor heat exchanger inlet pipe 41 to reach the indoor heat exchanger 18. After heating the indoor air in the indoor heat exchanger 18, the hot water is returned to the condenser 11 through the indoor heat exchanger outlet pipe 42, the fourth four-way valve 39, and the hot water return pipe 44.

[0028] After being cooled in the evaporator 13, the chilled water passes through the chilled water outlet pipe 21, the first four-way valve 20, and the outdoor heat exchanger inlet pipe 24 to the outdoor heat exchanger 22. After absorbing heat from the outside air in the outdoor heat exchanger 22, the chilled water is returned to the evaporator 13 through the outdoor heat exchanger outlet pipe 27, the second four-way valve 28, the chilled water pump inlet pipe 33, the chilled water pump 32, the chilled water discharge pipe 36, the third four-way valve 37, the four-way valve connecting pipe 40, the fourth four-way valve 39, and the chilled water return pipe 45.

[0029] <First transition mode> Figure 2 shows the first transition mode. The first transition mode is performed by a command from the control unit before the second transition mode and the heater mode, which will be described later. The following describes only the operation that changes the heat pump mode as described above.

[0030] The control unit controls the first four-way valve 20 to mix a portion of the hot water supplied from the hot water outlet pipe 19 with the chilled water flowing through the chilled water outlet pipe 21. By mixing a portion of the hot water with the chilled water, the chilled water flowing through the outdoor heat exchanger inlet pipe 24 becomes a medium temperature. In the following figures, the four-way valve controlled to mix the fluids is shown enclosed in a dashed circle. The medium-temperature heat transfer medium is shown with a dashed line.

[0031] After the medium-temperature chilled water absorbs heat in the outdoor heat exchanger 22, it passes through the chilled water pump 32 and reaches the fourth four-way valve 39. At the fourth four-way valve 39, the control unit mixes a portion of the medium-temperature chilled water with the hot water introduced from the indoor heat exchanger outlet piping 42. As a result, the flow rate of hot water supplied from the hot water circuit 5 to the chilled water circuit 7 at the first four-way valve 20 is recovered back into the hot water circuit 5 at the fourth four-way valve 39, thus balancing the heat transfer medium circulating in both the hot water circuit 5 and the chilled water circuit 7.

[0032] After being mixed in the fourth four-way valve 39, the hot water is returned to the condenser 11 through the hot water return pipe 44.

[0033] The remaining medium-temperature chilled water is returned to the evaporator 13 through the chilled water return pipe 45 via the fourth four-way valve 39. This return of medium-temperature chilled water to the evaporator 13 causes the temperature of the chilled water flowing out of the evaporator 13 to rise compared to when the system is operating in heat pump mode.

[0034] <Second transition mode> Figure 3 shows the second transition mode. The second transition mode is activated by a command from the control unit after the first transition mode and before the heater mode, which will be described later. The following description will only explain the operation that modifies the first transition mode as described above.

[0035] The control unit controls the first four-way valve 20 so that, similar to the heat pump mode, the entire volume of chilled water flowing through the chilled water discharge pipe 36 flows to the outdoor heat exchanger inlet pipe 24, and the entire volume of hot water flowing through the hot water discharge pipe 35 flows to the outdoor heat exchanger bypass pipe 26. As a result, the chilled water cooled in the evaporator 13 flows directly to the outdoor heat exchanger 22.

[0036] The control unit controls the second four-way valve 28, so that a portion of the chilled water flowing through the outdoor heat exchanger outlet pipe 27 is mixed with the hot water flowing through the outdoor heat exchanger bypass pipe 26. This cancels out the flow rate of the hot water mixed in the fourth four-way valve 39, balancing the heat transfer fluids circulating in the hot water circuit 5 and the chilled water circuit 7, respectively.

[0037] The remaining chilled water that has passed through the second four-way valve 28 is guided via the chilled water pump 32 through the third four-way valve 37 to the fourth four-way valve 39. At the fourth four-way valve 39, the control unit mixes a portion of the hot water flowing through the indoor heat exchange outlet pipe 42 with the chilled water. The chilled water, now at a medium temperature, is returned to the evaporator 13 through the chilled water return pipe 45. By returning medium-temperature chilled water to the evaporator 13 in this way, the temperature of the chilled water flowing out of the evaporator 13 rises compared to when it is in heat pump mode.

[0038] <Heater Mode> Figure 4 shows the heater mode. The heater mode is used when the outside air temperature is low, such as in winter, and sufficient heat absorption from the outdoor heat exchanger 22 cannot be expected even when heating is performed using the heat pump mode. In heater mode, the chilled water flowing out from the evaporator 13 is not directed to the outdoor heat exchanger 22, but an outdoor heat exchanger bypass pipe 26 is used.

[0039] Furthermore, in the heater mode shown in Figure 4, the hot water pump 30 is operating, while the chilled water pump 32 is stopped. The chilled water pump 32 may be operating while the hot water pump 30 is stopped, or both the chilled water pump 32 and the hot water pump 30 may be operating.

[0040] In the hot water circuit 5, the hot water heated in the condenser 11 passes through the first four-way valve 20 and is then led to the second four-way valve 28 via the outdoor heat exchanger bypass piping 26. As a result, no heat transfer medium flows to the outdoor heat exchanger 22. At the first four-way valve 20, the chilled water cooled in the evaporator 13 joins the hot water.

[0041] The hot water exiting the second four-way valve 28 is guided by the hot water pump 30 through the third four-way valve 37 to the indoor heat exchanger 18. In the indoor heat exchanger 18, the air inside the vehicle is heated by exchanging heat with it.

[0042] The hot water leaving the indoor heat exchanger 18 is led to the fourth four-way valve 39. Some of the hot water is returned to the condenser 11 through the hot water return pipe 44, and the remaining hot water is returned to the evaporator 13 through the chilled water return pipe 45.

[0043] In the chilled water circuit 7, the chilled water cooled in the evaporator 13 is guided to the first four-way valve 20 and merges with the hot water. The flow from there to the fourth four-way valve 39 is the same as that of the hot water described above. At the fourth four-way valve 39, the hot water that has flowed to the chilled water return pipe 45 is returned to the evaporator 13.

[0044] <Control Method> Next, the control method from the heat pump operation described above to the heater mode via the first and second transition modes will be explained using Figure 5.

[0045] While operating in the heat pump mode shown in Figure 1 (step S1), if the control unit determines that the amount of heat absorbed by the outdoor heat exchanger 22 falls below a predetermined value due to a decrease in the outside air temperature or frost formation on the outdoor heat exchanger, it decides to transition to the heater mode shown in Figure 4. Before transitioning to the heater mode, the first transition mode shown in Figure 2 is performed (step S2).

[0046] In the first transition mode of step S2, as shown in Figure 2, the first four-way valve 20 mixes a portion of the hot water with the chilled water to create medium-temperature chilled water, thereby increasing the temperature of the chilled water flowing out of the evaporator 13. This allows the temperature of the chilled water to be mixed with the hot water in the first four-way valve 20 during heater mode to be raised in advance.

[0047] In step S3, the control unit determines whether the difference between the temperature of the chilled water flowing into the outdoor heat exchanger 22 and the temperature of the intake air drawn into the outdoor heat exchanger 22 is greater than or equal to a first predetermined value. In the first transition mode, the chilled water in the outdoor heat exchanger 22 absorbs heat from the outside air, so the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 is lower than the temperature of the intake air (inlet temperature) that exchanges heat with the chilled water. Therefore, the difference between the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 and the intake air temperature is a negative value. If this negative difference becomes greater than or equal to the first predetermined value, the control unit determines that the chilled water temperature has risen, determines that the first transition mode has ended, and moves to the second transition mode (step S4). Alternatively, the evaporation temperature ET of the refrigerant in the evaporator 13 may be used instead of the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22.

[0048] In addition, in step S3, control may be performed to increase the rotational speed of the compressor 10. This can suppress the decrease in heating capacity of the indoor heat exchanger 18 due to the decrease in the amount of heat absorbed from the outside air during the first transition mode.

[0049] The inlet temperature of the chilled water and the intake air temperature in the outdoor heat exchanger 22 are measured by a temperature sensor (not shown) and transmitted to the control unit.

[0050] The first predetermined value is set to a value such that the chilled water in the outdoor heat exchanger 22 does not radiate heat to the outside air. The first predetermined value is predetermined and stored in the control unit. However, the first predetermined value can be changed by the user. The closer the first predetermined value is to 0, the closer the chilled water inlet temperature will be to the outside air temperature, and the temperature of the chilled water flowing out of the evaporator 13 can be increased.

[0051] In step S4, the second transition mode is performed. In the second transition mode, as shown in Figure 3, the fourth four-way valve 39 mixes a portion of the hot water with the chilled water to create medium-temperature chilled water, thereby increasing the temperature of the chilled water flowing out of the evaporator 13. This allows the temperature of the chilled water to be mixed with the hot water by the first four-way valve 20 during heater mode to be raised in advance.

[0052] In step S5, the control unit determines whether the difference between the evaporation temperature ET of the refrigerant in the evaporator 13 and the temperature of the intake air drawn into the outdoor heat exchanger 22 is greater than or equal to a second predetermined value. If this difference is greater than or equal to the second predetermined value, the second transition mode is terminated and the system switches to heater mode (step S6). Alternatively, the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 may be used instead of the evaporation temperature ET of the refrigerant in the evaporator 13.

[0053] In addition, in step S4, control may be performed to increase the rotational speed of the compressor 10. This suppresses the decrease in heating capacity of the indoor heat exchanger 18 due to the decrease in the amount of heat absorbed from the outside air during the second transition mode.

[0054] The evaporation temperature ET of the refrigerant is, for example, the saturated vapor temperature calculated by the control unit after measuring the pressure with a refrigerant pressure sensor (not shown) installed in the evaporator 13.

[0055] By setting the second predetermined value, which is the difference between the intake air temperature and the evaporation temperature ET, to a negative value, the evaporation temperature ET is set closer to 0 than the ambient air temperature, thereby bringing the temperature of the chilled water flowing out of the evaporator 13 closer to the ambient air temperature.

[0056] In step S6, the heater mode, as shown in Figure 4, cold water is mixed with hot water using the first four-way valve 20. At this time, since the temperature of the cold water has been raised as much as possible in advance by the first and second transition modes, the decrease in the temperature of the hot water after mixing can be suppressed.

[0057] The effects and advantages of this embodiment, as described above, are as follows. In heat pump mode, the heat transfer medium flowing through the indoor heat exchanger 18 is hot water for heating, and the heat transfer medium flowing through the outdoor heat exchanger 22 is chilled water for heat absorption. Before switching from heat pump mode to heater mode, a first transition mode is provided in which the hot water flowing through the indoor heat exchanger 18 is mixed with the chilled water flowing through the outdoor heat exchanger 22. This increases the temperature of the chilled water flowing through the outdoor heat exchanger 22, thereby increasing the temperature of the chilled water flowing out of the evaporator 13. Therefore, even when switching to heater mode, the temperature drop of the heat transfer medium can be kept to a minimum even when the chilled water flowing out of the evaporator 13 is mixed with the hot water flowing out of the condenser 11, and the decrease in heating capacity in the indoor heat exchanger 18 can be suppressed.

[0058] When the difference between the intake air temperature and the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 exceeds a predetermined value, it is determined that the chilled water temperature has risen, and the first transition mode is terminated. This allows the chilled water temperature to rise to the same level as the outside air temperature.

[0059] A portion of the chilled water flowing from the outdoor heat exchanger 22 to the evaporator 13 is mixed with the hot water flowing from the indoor heat exchanger 18 to the condenser 11. This prevents the mixing of chilled water upstream of the indoor heat exchanger 18, which would cause a decrease in the temperature of the hot water, thus maintaining the temperature of the hot water flowing to the indoor heat exchanger 18 and ensuring heating capacity.

[0060] A second transition mode is provided in which a portion of the hot water flowing from the indoor heat exchanger 18 to the condenser 11 is mixed with the chilled water flowing from the outdoor heat exchanger 22 to the evaporator 13. This increases the temperature of the chilled water flowing to the evaporator 13, thereby increasing the evaporation temperature ET of the refrigerant and raising the temperature of the chilled water flowing out of the evaporator 13.

[0061] In the second transition mode, the chilled water discharged from the evaporator 13 is flowed to the outdoor heat exchanger 22 without being mixed with the hot water. This allows the chilled water temperature to be higher than in the first transition mode while ensuring heat absorption from the air in the outdoor heat exchanger 22.

[0062] When either the first or second transition mode is activated, the amount of heat absorbed from the outside air gradually decreases, and the amount of heating in the indoor heat exchanger 18 decreases. To compensate for this decrease in heating, the rotational speed of the compressor is increased.

[0063] In the embodiment described above, both the first and second transition modes were used, but either one of these modes may be used. For example, after step S3 as shown in Figure 5, the second transition mode in step S4 may be omitted, and the system may proceed directly to the heater mode in step S6.

[0064] Alternatively, as shown in Figure 6, after executing the first or second transition mode in step S21, a termination determination may be made based on the relationship between the refrigerant evaporation temperature ET and the intake air temperature, as in step S5, and the system may proceed to the heater mode in step S6. Alternatively, the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 may be used instead of the evaporation temperature ET of the refrigerant in the evaporator 13.

[0065] [Second Embodiment] Next, a second embodiment of this disclosure will be described with reference to Figure 7, etc. The vehicle air conditioning system 1 shown in Figure 7 has a different configuration of the heat transfer medium circuit compared to the first embodiment. In the following description, the configurations that differ from the first embodiment will be described, and the same components will be denoted by the same reference numerals and their descriptions will be omitted.

[0066] The hot water circuit 5 is a flow path that primarily supplies hot water heated in the condenser 11 to the indoor heat exchanger (temperature control equipment) 18, and returns the hot water that flows out of the indoor heat exchanger 18 to the condenser 11.

[0067] The hot water circuit 5 includes a hot water pump 30 connected to a hot water outlet pipe 19. The cold water circuit 7 includes a cold water pump 32 connected to a cold water outlet pipe 21. The rotational speed, i.e., the flow rate, of the hot water pump 30 and the cold water pump 32 is controlled by the control unit.

[0068] The hot water discharge pipe 35 connected to the hot water pump 30, and the cold water discharge pipe 36 connected to the cold water pump 32, are connected to the indoor heat exchanger 18, the outdoor heat exchanger 22, and the battery heat exchanger 50.

[0069] An upstream three-way valve 52a is provided in the indoor heat exchanger inlet piping 41 on the upstream side of the indoor heat exchanger 18, and an indoor heat exchanger downstream three-way valve 52b is provided in the indoor heat exchanger outlet piping 42 on the downstream side of the indoor heat exchanger 18. The opening degree of the indoor heat exchanger upstream three-way valve 52a is controlled by the control unit and allows hot water from the hot water pump 30 and cold water from the cold water pump 32 to flow to the indoor heat exchanger 18. The indoor heat exchanger downstream three-way valve 52b is controlled by the control unit and allows hot water or cold water that has flowed out of the indoor heat exchanger 18 to flow to the hot water return piping 44 and the cold water return piping 45. The opening degrees of the indoor heat exchanger upstream three-way valve 52a and the indoor heat exchanger downstream three-way valve 52b are controlled synchronously by a single actuator. Note that this disclosure is not limited to the three-way valves described above, and other three-way valves or two-way valves may be combined.

[0070] An outdoor heat exchanger upstream three-way valve 53a is provided in the outdoor heat exchanger inlet piping 24 on the upstream side of the outdoor heat exchanger 22, and an outdoor heat exchanger downstream three-way valve 53b is provided in the outdoor heat exchanger outlet piping 27 on the downstream side of the outdoor heat exchanger 22. The opening degree of the outdoor heat exchanger upstream three-way valve 53a is controlled by the control unit and allows hot water from the hot water pump 30 and cold water from the cold water pump 32 to flow to the outdoor heat exchanger 22. The outdoor heat exchanger downstream three-way valve 53b is controlled by the control unit and allows hot water or cold water that has flowed out of the outdoor heat exchanger 22 to flow to the hot water return piping 44 and the cold water return piping 45. The opening degrees of the outdoor heat exchanger upstream three-way valve 53a and the outdoor heat exchanger downstream three-way valve 53b are controlled synchronously by a single actuator. Note that this disclosure is not limited to the three-way valves described above, and other three-way valves or two-way valves may be combined.

[0071] A three-way valve 56a is provided in the battery heat exchanger inlet piping 54 on the upstream side of the battery heat exchanger 50, and a three-way valve 56b is provided in the battery heat exchanger outlet piping 55 on the downstream side of the battery heat exchanger 50. The opening degree of the battery heat exchanger upstream three-way valve 56a is controlled by a control unit (not shown), allowing hot water from the hot water pump 30 and cold water from the cold water pump 32 to flow to the battery heat exchanger 50. The battery heat exchanger downstream three-way valve 56b is controlled by a control unit (not shown), allowing hot water or cold water that has flowed out of the battery heat exchanger 50 to flow to the hot water return piping 44 and the cold water return piping 45. The opening degrees of the battery heat exchanger upstream three-way valve 56a and the battery heat exchanger downstream three-way valve 56b are controlled synchronously by a single actuator. Note that this disclosure is not limited to the three-way valves described above, and other three-way valves or two-way valves may be combined.

[0072] A battery water pump 58, whose operation is controlled by a control unit, is provided in the battery heat exchanger inlet pipe 54. Upstream of the battery water pump 58, a connecting pipe 59 is provided that connects the battery heat exchanger inlet pipe 54 and the battery heat exchanger outlet pipe 55.

[0073] A heat transfer medium bypass pipe 47 is provided between the hot water outlet pipe 19 upstream of the hot water pump 30 and the cold water outlet pipe 21 upstream of the cold water pump 32. Hot water flows from the hot water circuit 5 to the cold water circuit 7, or cold water flows from the cold water circuit 7 to the hot water circuit 5, through the heat transfer medium bypass pipe 47. A reserve tank 48 for storing hot water or cold water is provided in the heat transfer medium bypass pipe 47.

[0074] Next, we will describe each operating mode using the vehicle air conditioning system 1 configured as described above. <Heat pump mode> The heat pump mode is explained using Figure 7. In the refrigerant circuit 3, the refrigerant compressed by the compressor 10 is sent to the condenser 11 where it condenses. As the refrigerant condenses, the latent heat of condensation is transferred to the hot water, which is the heat transfer medium flowing through the condenser 11, causing it to heat up.

[0075] The liquid refrigerant exiting the condenser 11 is depressurized by the expansion valve 12 and guided to the evaporator 13. In the evaporator 13, the refrigerant evaporates, and the latent heat of vaporization is absorbed from the chilled water, which is the heat transfer medium circulating in the evaporator 13, thereby cooling the chilled water.

[0076] The hot water heated in the condenser 11 is guided by the hot water pump 30 through the three-way valve 52a upstream of the indoor heat exchanger to the indoor heat exchanger 18. In the indoor heat exchanger 18, the air inside the vehicle is heated by exchanging heat with it.

[0077] The hot water that exits the indoor heat exchanger 18 is returned to the condenser 11 via the hot water return pipe 44, passing through the three-way valve 52b downstream of the indoor heat exchanger.

[0078] The chilled water cooled in the evaporator 13 is guided by the chilled water pump 32 through the three-way valve 53a upstream of the outdoor heat exchanger to the outdoor heat exchanger 22. In the outdoor heat exchanger 22, the chilled water is heated by absorbing heat from the outside air.

[0079] The chilled water that exits the outdoor heat exchanger 22 is returned to the evaporator 13 through the three-way valve 53b downstream of the outdoor heat exchanger and the chilled water return pipe 45.

[0080] <First transition mode> Figure 8 shows the first transition mode. The following describes only the operations that are changed from the heat pump mode described above.

[0081] The control unit controls the three-way valve 52a upstream of the indoor heat exchanger, distributing the hot water supplied from the hot water discharge pipe 35 to the indoor heat exchanger inlet pipe 41 and the cold water discharge pipe 36. The hot water distributed to the cold water discharge pipe 36 merges with cold water upstream of the three-way valve 53a upstream of the outdoor heat exchanger to become medium-temperature cold water, which then flows through the three-way valve 53a upstream of the outdoor heat exchanger to the outdoor heat exchanger inlet pipe 24. In the following figures, three-way valves controlled to mix or distribute fluids are indicated by dashed circles.

[0082] Medium-temperature chilled water is led to the outdoor heat exchanger 22, where it absorbs heat from the air (outside air), and then led to the outdoor heat exchanger downstream three-way valve 53b via the outdoor heat exchanger outlet pipe 27. At the outdoor heat exchanger downstream three-way valve 53b, the chilled water, now at a medium temperature, is distributed to the hot water return pipe 44 and the chilled water return pipe 45. As a result, the flow rate of hot water supplied from the hot water circuit 5 to the chilled water circuit 7 at the indoor heat exchanger upstream three-way valve 52a is recovered back into the hot water circuit 5 at the outdoor heat exchanger downstream three-way valve 53b, thus balancing the heat transfer medium circulating in the hot water circuit 5 and the chilled water circuit 7.

[0083] The medium-temperature chilled water, guided to the chilled water return pipe 45, is returned to the evaporator 13. This return of medium-temperature chilled water to the evaporator 13 causes the temperature of the chilled water flowing out of the evaporator 13 to rise compared to when operating in heat pump mode.

[0084] The first transition mode described above can be modified as shown in Figure 9. As shown in Figure 9, the three-way valve 52a upstream of the indoor heat exchanger directs hot water only to the indoor heat exchanger inlet pipe 41, and controls the three-way valve 53a upstream of the outdoor heat exchanger to mix a portion of the hot water supplied from the hot water discharge pipe 35 with the cold water supplied from the cold water discharge pipe 36. This allows medium-temperature cold water to flow to the outdoor heat exchanger inlet pipe 24. Other operations are the same as in the first transition mode shown in Figure 8.

[0085] <Second transition mode> Figure 10 shows the second transition mode. The following describes only the operations that change from the first transition mode described above.

[0086] The control unit controls the three-way valve 53b downstream of the outdoor heat exchanger, mixing a portion of the hot water flowing through the hot water return pipe 44 with the chilled water introduced from the outdoor heat exchanger outlet pipe 27. The chilled water, now at a medium temperature due to the mixing of some of the hot water, is returned to the evaporator 13 through the chilled water return pipe 45. By returning this medium-temperature chilled water to the evaporator 13, the temperature of the chilled water flowing out of the evaporator 13 becomes higher than in the heat pump mode.

[0087] The control unit controls the upstream three-way valve 53a of the outdoor heat exchanger, mixing a portion of the chilled water supplied from the chilled water discharge pipe 36 with the hot water flowing through the hot water discharge pipe 35. This cancels out the flow rate of the hot water mixed in the downstream three-way valve 53b of the outdoor heat exchanger, balancing the heat transfer medium circulating in the hot water circuit 5 and the chilled water circuit 7, respectively.

[0088] The second transition mode described above can be modified as shown in Figure 11. As shown in Figure 11, the outdoor heat exchanger upstream three-way valve 53a may direct the chilled water from the chilled water discharge pipe 36 only to the outdoor heat exchanger inlet pipe 24, while the indoor heat exchanger upstream three-way valve 52a may mix a portion of the chilled water from the chilled water discharge pipe 36 with the hot water. Other operations are the same as the second transition mode in Figure 10.

[0089] <Heater Mode> Figure 12 shows the heater mode. Unlike the heat pump mode, in the heater mode, similar to the first embodiment, the chilled water flowing out of the evaporator 13 is not led to the outdoor heat exchanger 22, but is mixed with hot water and then led to the indoor heat exchanger 18. The hot water flowing out of the indoor heat exchanger 18 is distributed to the condenser 11 and the evaporator 13.

[0090] The control unit commands the chilled water pump 32 to stop, and only the hot water pump 30 to operate. The chilled water flowing out of the evaporator 13 passes through the heat transfer medium bypass pipe 47 and mixes with the hot water flowing through the hot water outlet pipe 19. The mixed hot water is then guided through the three-way valve 52a upstream of the indoor heat exchanger to the indoor heat exchanger 18. In the indoor heat exchanger 18, the air inside the vehicle is heated by exchanging heat with it.

[0091] The hot water exiting the indoor heat exchanger 18 passes through the three-way valve 52b downstream of the indoor heat exchanger and is distributed to the hot water return pipe 44 and the chilled water return pipe 45. Some of the hot water is returned to the condenser 11, and the remaining hot water is returned to the evaporator 13.

[0092] For the outdoor heat exchanger 22, the upstream three-way valve 53a and the downstream three-way valve 53b are completely closed to prevent the flow of the heat transfer medium (hot water or cold water).

[0093] In addition, as shown in Figure 13, the heater mode may also involve activating the chilled water pump 32 as well as the hot water pump 30. In this case, the chilled water is mixed with the hot water at the three-way valve 52a upstream of the indoor heat exchanger. Alternatively, only the chilled water pump 32 may be started. In this case, the hot water will pass through the heat transfer medium bypass pipe 47 and mix with the chilled water flowing through the chilled water outlet pipe 21.

[0094] <Control Method> The control method for transitioning from heat pump operation to heater mode via the first and second transition modes is the same as that described in the first embodiment using Figures 5 and 6, so its explanation will be omitted.

[0095] The effects and advantages of this embodiment, as described above, are as follows. In heat pump mode, the heat transfer medium flowing through the indoor heat exchanger 18 is hot water for heating, and the heat transfer medium flowing through the outdoor heat exchanger 22 is chilled water for heat absorption. Before switching from heat pump mode to heater mode, a first transition mode is provided in which the hot water flowing through the indoor heat exchanger 18 is mixed with the chilled water flowing through the outdoor heat exchanger 22. This increases the temperature of the chilled water flowing through the outdoor heat exchanger 22, thereby increasing the temperature of the chilled water flowing out of the evaporator 13. Therefore, even when switching to heater mode, the temperature drop of the heat transfer medium can be kept to a minimum even when the chilled water flowing out of the evaporator 13 is mixed with the hot water flowing out of the condenser 11, and the decrease in heating capacity in the indoor heat exchanger 18 can be suppressed.

[0096] When the difference between the intake air temperature and the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 exceeds a predetermined value, it is determined that the chilled water temperature has risen, and the first transition mode is terminated. This allows the chilled water temperature to rise to the same level as the outside air temperature.

[0097] A portion of the chilled water flowing from the outdoor heat exchanger 22 to the evaporator 13 is mixed with the hot water flowing from the indoor heat exchanger 18 to the condenser 11. This prevents the mixing of chilled water upstream of the indoor heat exchanger 18, which would cause a decrease in the temperature of the hot water, thus maintaining the temperature of the hot water flowing to the indoor heat exchanger 18 and ensuring heating capacity.

[0098] A second transition mode is provided in which a portion of the hot water flowing from the indoor heat exchanger 18 to the condenser 11 is mixed with the chilled water flowing from the outdoor heat exchanger 22 to the evaporator 13. This increases the temperature of the chilled water flowing to the evaporator 13, thereby increasing the evaporation temperature ET of the refrigerant and raising the temperature of the chilled water flowing out of the evaporator 13.

[0099] In the second transition mode, the chilled water discharged from the evaporator 13 is flowed to the outdoor heat exchanger 22 without being mixed with the hot water. This allows the chilled water temperature to be higher than in the first transition mode while ensuring heat absorption from the air in the outdoor heat exchanger 22.

[0100] When either the first or second transition mode is activated, the amount of heat absorbed from the outside air gradually decreases, and the amount of heating in the indoor heat exchanger 18 decreases. To compensate for this decrease in heating, the rotational speed of the compressor is increased.

[0101] In the embodiment described above, both the first and second transition modes were used, but either one of these modes may be used. For example, after step S3 as shown in Figure 5, the second transition mode in step S4 may be omitted, and the system may proceed directly to the heater mode in step S6.

[0102] Alternatively, as shown in Figure 6, after executing the first or second transition mode in step S21, a termination determination may be made based on the relationship between the refrigerant evaporation temperature ET and the intake air temperature, as in step S5, and the system may proceed to the heater mode in step S6. Alternatively, the inlet temperature of the chilled water flowing through the outdoor heat exchanger 22 may be used instead of the evaporation temperature ET of the refrigerant in the evaporator 13.

[0103] The temperature control systems and their control methods described in each of the embodiments described above can be understood, for example, as follows.

[0104] A temperature control system (1) according to a first aspect of the present disclosure comprises a refrigerant circuit (3) having a compressor (10) for compressing a refrigerant, a high-pressure side heat exchanger (11) for releasing heat from the refrigerant compressed by the compressor, an expansion valve (12) for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger (13) for evaporating the refrigerant expanded by the expansion valve; a heat transfer medium circuit (5,7) through which a heat transfer medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates; and a control unit for controlling the refrigerant circuit and the heat transfer medium circuit, wherein the heat transfer medium circuit comprises a temperature control device (18) for exchanging heat between the heat transfer medium and a temperature control target, and an outdoor heat exchanger (22) for exchanging heat between the heat transfer medium and outside air, and the control unit The system includes a heat pump mode in which the heat transfer medium flowing out of the high-pressure heat exchanger is guided to the temperature control equipment and the heat transfer medium flowing out of the low-pressure heat exchanger is guided to the outdoor heat exchanger; a heater mode in which at least a portion of the heat transfer medium flowing out of the high-pressure heat exchanger and the heat transfer medium flowing out of the low-pressure heat exchanger are mixed and at least a portion of the heat transfer medium flowing out of the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a first transition mode in which, before switching from the heat pump mode to the heater mode, the heat transfer medium flowing through the temperature control equipment is mixed with the heat transfer medium flowing through the outdoor heat exchanger.

[0105] In heat pump mode, the heat transfer medium circulating through the temperature control equipment is a relatively high-temperature heating medium (hot), while the heat transfer medium circulating through the outdoor heat exchanger is a relatively low-temperature heat transfer medium (cold) for heat absorption. Before switching from heat pump mode to heater mode, a first transition mode is provided in which the heat transfer medium (hot) circulating through the temperature control equipment is mixed with the heat transfer medium (cold) circulating through the outdoor heat exchanger. This increases the temperature of the heat transfer medium (cold) circulating through the outdoor heat exchanger, thereby increasing the temperature of the heat transfer medium (cold) flowing out of the low-pressure side heat exchanger. Therefore, even when switching to heater mode, mixing the heat transfer medium (cold) flowing out of the low-pressure side heat exchanger with the heat transfer medium (hot) flowing out of the high-pressure side heat exchanger minimizes the temperature drop of the heat transfer medium, thereby suppressing a decrease in the heating capacity of the temperature control equipment.

[0106] In the first embodiment, the temperature control system according to a second aspect of the present disclosure terminates the first transition mode when the control unit, in the first transition mode, terminates when the difference between the inlet temperature of the fluid that exchanges heat with the heat medium flowing through the outdoor heat exchanger and the inlet temperature of the fluid that exchanges heat with the heat medium flowing through the outdoor heat exchanger exceeds a predetermined value, or when the difference between the evaporation temperature of the refrigerant flowing through the low-pressure side heat exchanger and the inlet temperature of the fluid that exchanges heat with the heat medium flowing through the outdoor heat exchanger exceeds a predetermined value.

[0107] In the first transition mode, the heat transfer medium absorbs heat in the outdoor heat exchanger. Therefore, the inlet temperature of the cold heat transfer medium flowing through the outdoor heat exchanger is lower than the inlet temperature of the fluid (e.g., outside air) that exchanges heat with the cold heat transfer medium. Consequently, the difference between the inlet temperature of the cold heat transfer medium flowing through the outdoor heat exchanger and the inlet temperature of the fluid that exchanges heat with the cold heat transfer medium is a negative value. If this negative difference exceeds a predetermined value, it can be determined that the chilled water temperature has risen, and the first transition mode can be terminated. Furthermore, the difference between the evaporation temperature of the refrigerant and the inlet temperature of the fluid exchanging heat with the heat transfer medium (cold) in the outdoor heat exchanger will be a negative value. If this negative difference exceeds a predetermined value, it can be determined that the amount of heat absorbed by the refrigerant from the fluid has decreased, and the first transition mode can be terminated. When the first transition mode ends, the system transitions to, for example, the heater mode or the second transition mode described later.

[0108] In the third aspect of the present disclosure, the temperature control system, in the first or second aspect, is configured such that the first transition mode mixes a portion of the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure side heat exchanger with the heat transfer medium flowing from the temperature control device to the high-pressure side heat exchanger.

[0109] A portion of the cold heat transfer fluid flowing from the outdoor heat exchanger to the low-pressure heat exchanger is mixed with the hot heat transfer fluid flowing from the temperature control equipment to the high-pressure heat exchanger. This prevents the mixing of cold heat transfer fluid upstream of the temperature control equipment, which would cause a decrease in the temperature of the hot heat transfer fluid, thus maintaining the temperature of the hot heat transfer fluid flowing to the temperature control equipment and ensuring heating capacity.

[0110] A temperature control system according to a fourth aspect of the present disclosure, in the first or second aspect, has a second transition mode in which the control unit mixes a portion of the heat transfer medium flowing from the temperature control device to the high-pressure side heat exchanger with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure side heat exchanger.

[0111] A second transition mode is introduced in which a portion of the heat transfer medium (hot) flowing from the temperature control equipment to the high-pressure heat exchanger is mixed with the heat transfer medium (cold) flowing from the outdoor heat exchanger to the low-pressure heat exchanger. This increases the temperature of the heat transfer medium (cold) flowing to the low-pressure heat exchanger, thereby increasing the evaporation temperature of the refrigerant and increasing the temperature of the heat transfer medium (cold) flowing out of the low-pressure heat exchanger. In the second transition mode, the chilled water discharged from the evaporator 13 is flowed to the outdoor heat exchanger 22 without being mixed with the hot water. This allows the chilled water temperature to be higher than in the first transition mode while ensuring heat absorption from the air in the outdoor heat exchanger 22. The second transition mode can be performed after the first transition mode.

[0112] The fifth aspect of the present disclosure is a temperature control system in which, in any of the first to fourth aspects, the rotational speed of the compressor is increased during the first transition mode.

[0113] When either the first or second transition mode is activated, the amount of heat absorbed from the outside air gradually decreases, resulting in a reduction in the amount of heating provided by the temperature control equipment. To compensate for this reduction in heating, the compressor speed was increased.

[0114] The temperature control system according to the sixth aspect of this disclosure increases the rotational speed of the compressor during the second transition mode in any of the first to fifth aspects.

[0115] When either the first or second transition mode is activated, the amount of heat absorbed from the outside air gradually decreases, resulting in a reduction in the amount of heating provided by the temperature control equipment. To compensate for this reduction in heating, the compressor speed was increased.

[0116] A temperature control system according to a seventh aspect of this disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; a heat transfer medium circuit through which a heat transfer medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates; and a control unit for controlling the refrigerant circuit and the heat transfer medium circuit, wherein the heat transfer medium circuit comprises a temperature control device that exchanges heat between the heat transfer medium and a temperature control target, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and the outside air, and the control unit flows out from the high-pressure side heat exchanger. The system includes a heat pump mode in which the prepared heat transfer medium is guided to the temperature control equipment and the heat transfer medium discharged from the low-pressure heat exchanger is guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium discharged from the high-pressure heat exchanger and at least a portion of the heat transfer medium discharged from the low-pressure heat exchanger are mixed and at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a second transition mode in which a portion of the heat transfer medium flowing from the temperature control equipment to the high-pressure heat exchanger is mixed with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure heat exchanger.

[0117] In heat pump mode, the heat transfer medium circulating through the temperature control equipment is a relatively high-temperature heating medium (hot), while the heat transfer medium circulating through the outdoor heat exchanger is a relatively low-temperature heat transfer medium (cold) for heat absorption. Before switching from heat pump mode to heater mode, a second transition mode is introduced in which a portion of the heat transfer medium (hot) flowing from the temperature control equipment to the high-pressure side heat exchanger is mixed with the heat transfer medium (cold) flowing from the outdoor heat exchanger to the low-pressure side heat exchanger. This increases the temperature of the heat transfer medium (cold) flowing to the low-pressure side heat exchanger, thereby increasing the evaporation temperature of the refrigerant and increasing the temperature of the heat transfer medium (cold) flowing out of the low-pressure side heat exchanger. In the second transition mode, the chilled water discharged from the evaporator 13 is flowed to the outdoor heat exchanger 22 without being mixed with the hot water. This allows the chilled water temperature to be higher than in the first transition mode while ensuring heat absorption from the air in the outdoor heat exchanger 22. Once the second transition mode ends, the system will transition to, for example, the heater mode.

[0118] A control method for a temperature control system according to a first aspect of the present disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; and a heat medium circuit through which a heat medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates, wherein the heat medium circuit comprises a temperature control device for exchanging heat between the heat medium and a temperature control target, and an outdoor heat exchanger for exchanging heat between the heat medium and the outside air, wherein the heat medium that flows out from the high-pressure side heat exchanger is used as the temperature control method for a temperature control system. The system includes a heat pump mode in which the heat transfer medium flowing out of the low-pressure heat exchanger is guided to the temperature control equipment and also guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium flowing out of the high-pressure heat exchanger and at least a portion of the heat transfer medium flowing out of the low-pressure heat exchanger are mixed, at least a portion of the heat transfer medium flowing out of the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a first transition mode in which, before switching from the heat pump mode to the heater mode, the heat transfer medium flowing through the temperature control equipment is mixed with the heat transfer medium flowing through the outdoor heat exchanger.

[0119] A control method for a temperature control system according to a second aspect of the present disclosure comprises a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant expanded by the expansion valve; and a heat transfer medium circuit through which a heat transfer medium that exchanges heat with the refrigerant in the high-pressure side heat exchanger and the low-pressure side heat exchanger circulates, wherein the heat transfer medium circuit comprises a temperature control device that exchanges heat between the heat transfer medium and a temperature control target, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and outside air, wherein the heat transfer medium that flows out from the high-pressure side heat exchanger The system includes a heat pump mode in which the heat transfer medium flowing from the low-pressure heat exchanger is guided to the temperature control equipment and also guided to the outdoor heat exchanger; a heater mode in which the heat transfer medium flowing from the high-pressure heat exchanger and at least a portion of the heat transfer medium flowing from the low-pressure heat exchanger are mixed, at least a portion of the heat transfer medium flowing from the high-pressure heat exchanger is guided to the temperature control equipment and the mixed heat transfer medium is guided to the high-pressure heat exchanger and the low-pressure heat exchanger; and a second transition mode in which a portion of the heat transfer medium flowing from the temperature control equipment to the high-pressure heat exchanger is mixed with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure heat exchanger. [Explanation of symbols]

[0120] 1. Vehicle air conditioning system (temperature control system) 3. Refrigerant Circuit 5 Hot water circuit (heat medium circuit) 7 Chilled water circuit (heat medium circuit) 10 Compressor 11. Condenser (High-pressure side heat exchanger) 12 Expansion valve 13. Evaporator (low-pressure heat exchanger) 18 Indoor heat exchanger (temperature control equipment) 19 Hot water outlet piping 20 First four-way valve 21 Chilled water outlet piping 22 Outdoor heat exchanger 24 Outdoor heat exchanger inlet piping 26 Outdoor heat exchanger bypass piping 27 Outdoor heat exchanger outlet piping 28 Second four-way valve 30 Hot water pump 31 Hot water pump inlet piping 32 Chilled water pump 33 Chilled water pump inlet piping 35 Hot water discharge piping 36 Cold water discharge piping 37 Third four-way valve 39 Fourth four-way valve 40 Four-way valve connection piping 41 Indoor heat exchanger inlet piping 42 Indoor heat exchanger outlet piping 44 Hot water return piping 45. Chilled water return piping 47 Heat transfer fluid bypass piping 48 Reserve Tank 50 Heat exchanger for batteries (rechargeable batteries) 52a Indoor heat exchanger upstream three-way valve 52b Indoor heat exchanger downstream three-way valve 53a Outdoor heat exchanger upstream three-way valve 53b Outdoor heat exchanger downstream three-way valve 54 Heat exchanger inlet piping for battery 55 Heat exchanger outlet piping for battery 56a Three-way valve upstream of heat exchanger for battery 56b Battery Heat Exchanger Downstream Three-Way Valve 58 Battery-powered water pump 59 Connection Distribution

Claims

1. A refrigerant circuit having a compressor for compressing the refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has released heat from the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant that has expanded in the expansion valve, A heat transfer medium circuit through which a heat transfer medium circulates in the high-pressure side heat exchanger and the low-pressure side heat exchanger, The system comprises a control unit that controls the refrigerant circuit and the heat transfer medium circuit, The heat transfer circuit comprises a temperature control device that exchanges heat between the heat transfer medium and the temperature to be controlled, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and the outside air. The control unit has a heat pump mode in which it guides the heat transfer medium that has flowed out from the high-pressure side heat exchanger to the temperature control equipment and guides the heat transfer medium that has flowed out from the low-pressure side heat exchanger to the outdoor heat exchanger, A heater mode that mixes at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger with the heat transfer medium discharged from the low-pressure heat exchanger, guides at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger to the temperature control equipment, and guides the mixed heat transfer medium to the high-pressure heat exchanger and the low-pressure heat exchanger, Before switching from the heat pump mode to the heater mode, a first transition mode is performed in which the heat transfer medium flowing through the temperature control equipment is mixed with the heat transfer medium flowing through the outdoor heat exchanger. A temperature control system that has the following features.

2. In the first transition mode, the control unit, When the difference between the temperature of the heat transfer medium flowing through the outdoor heat exchanger and the inlet temperature of the fluid exchanging heat with the heat transfer medium exceeds a predetermined value, or, When the difference between the evaporation temperature of the refrigerant flowing through the low-pressure side heat exchanger and the temperature of the fluid exchanging heat with the heat transfer medium flowing through the outdoor heat exchanger exceeds a predetermined value, The temperature control system according to claim 1, which terminates the first transition mode.

3. The temperature control system according to claim 1 or 2, wherein the first transition mode is a mixture of a portion of the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure side heat exchanger with the heat transfer medium flowing from the temperature control equipment to the high-pressure side heat exchanger.

4. The temperature control system according to claim 1 or 2, wherein the control unit has a second transition mode in which it mixes a portion of the heat transfer medium flowing from the temperature control device to the high-pressure side heat exchanger with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure side heat exchanger.

5. The temperature control system according to claim 1, wherein the rotational speed of the compressor is increased during the first transition mode.

6. The temperature control system according to claim 4, wherein the rotational speed of the compressor is increased during the second transition mode.

7. A refrigerant circuit having a compressor for compressing the refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has released heat from the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant that has expanded in the expansion valve, A heat transfer medium circuit through which a heat transfer medium circulates in the high-pressure side heat exchanger and the low-pressure side heat exchanger, The system comprises a control unit that controls the refrigerant circuit and the heat transfer medium circuit, The heat transfer circuit comprises a temperature control device that exchanges heat between the heat transfer medium and the temperature to be controlled, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and the outside air. The control unit has a heat pump mode in which it guides the heat transfer medium that has flowed out from the high-pressure side heat exchanger to the temperature control equipment and guides the heat transfer medium that has flowed out from the low-pressure side heat exchanger to the outdoor heat exchanger, A heater mode that mixes at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger with the heat transfer medium discharged from the low-pressure heat exchanger, guides at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger to the temperature control equipment, and guides the mixed heat transfer medium to the high-pressure heat exchanger and the low-pressure heat exchanger, A second transition mode in which a portion of the heat transfer medium flowing from the temperature control device to the high-pressure side heat exchanger is mixed with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure side heat exchanger, A temperature control system that has the following features.

8. The temperature control system according to claim 7, wherein the rotational speed of the compressor is increased during the second transition mode.

9. A refrigerant circuit having a compressor for compressing the refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has released heat from the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant that has expanded in the expansion valve, The high-pressure side heat exchanger and the low-pressure side heat exchanger include a heat transfer medium circuit through which a heat transfer medium that exchanges heat with a refrigerant circulates, The aforementioned heat transfer circuit is a control method for a temperature control system comprising a temperature control device that exchanges heat between a heat transfer medium and a temperature-controlled object, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and outside air. A heat pump mode that guides the heat transfer medium flowing out from the high-pressure side heat exchanger to the temperature control equipment, and guides the heat transfer medium flowing out from the low-pressure side heat exchanger to the outdoor heat exchanger, A heater mode that mixes at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger with the heat transfer medium discharged from the low-pressure heat exchanger, guides at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger to the temperature control equipment, and guides the mixed heat transfer medium to the high-pressure heat exchanger and the low-pressure heat exchanger, Before switching from the heat pump mode to the heater mode, a first transition mode is performed in which the heat transfer medium flowing through the temperature control equipment is mixed with the heat transfer medium flowing through the outdoor heat exchanger. A control method for a temperature control system having the following features.

10. A refrigerant circuit having a compressor for compressing the refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has released heat from the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant that has expanded in the expansion valve, The high-pressure side heat exchanger and the low-pressure side heat exchanger include a heat transfer medium circuit through which a heat transfer medium that exchanges heat with a refrigerant circulates, The aforementioned heat transfer circuit is a control method for a temperature control system comprising a temperature control device that exchanges heat between a heat transfer medium and a temperature-controlled object, and an outdoor heat exchanger that exchanges heat between the heat transfer medium and outside air. A heat pump mode that guides the heat transfer medium flowing out from the high-pressure side heat exchanger to the temperature control equipment, and guides the heat transfer medium flowing out from the low-pressure side heat exchanger to the outdoor heat exchanger, A heater mode that mixes at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger with the heat transfer medium discharged from the low-pressure heat exchanger, guides at least a portion of the heat transfer medium discharged from the high-pressure heat exchanger to the temperature control equipment, and guides the mixed heat transfer medium to the high-pressure heat exchanger and the low-pressure heat exchanger, A second transition mode in which a portion of the heat transfer medium flowing from the temperature control device to the high-pressure side heat exchanger is mixed with the heat transfer medium flowing from the outdoor heat exchanger to the low-pressure side heat exchanger, A control method for a temperature control system having the following features.

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