Electric vehicle temperature control system

Abstract

To provide a system which adjusts the temperature of a component group of an electric vehicle without using a heating device.SOLUTION: A temperature control system of an electric vehicle comprises: a first cooling circuit having a first coolant pump, a component group which has relatively low allowable temperature and a first heat exchanger into which a coolant that has received heat from the component group flows; a second cooling circuit having a second coolant pump, a component group which has relatively high allowable temperature and a second heat exchanger into which a coolant that has received heat from the component group flows; a bypass circuit which branches from the second cooling circuit, passes through a radiator and joins the second cooling circuit again; a channel switching valve which is provided in a branch part or a joining part between the bypass circuit and the second cooling circuit; a first temperature acquisition device which acquires temperature of the coolant of the first cooling circuit; a second temperature acquisition device which acquires temperature of the coolant of the second cooling circuit; and a heat pump system which is made of a circulation path in which the first heat exchanger, a compressor, the second heat exchanger and an expansion valve are arranged in this order; and a controller.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a temperature control system for an electric vehicle. [Background technology]

[0002] Batteries used in electric vehicles experience performance degradation, such as charging efficiency, at low temperatures. To address this issue, temperature control systems for raising the temperature of batteries are known. While temperature control systems using a heating device such as a PTC heater are known, activating the heating device increases power consumption. To address this issue, Patent Document 1 discloses a temperature control system that uses a valve capable of switching between multiple refrigerant paths to connect a heat pump system for interior air conditioning to a refrigerant path for regulating the battery temperature, thereby enabling battery temperature regulation without using a heating device such as a PTC heater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US2019 / 0070924A1 Summary of the Invention [Problem to be solved by the invention]

[0004] The temperature control system described in the above document is based on the premise that the temperature range of the vehicle interior air conditioning system and the temperature range of the battery temperature control system are the same. Therefore, when the temperature range of the battery temperature control system needs to be higher than the temperature range of the vehicle interior air conditioning system, such as when an all-solid-state battery is used as the battery, the temperature control system described in the above document is difficult to apply. Similarly, when attempting to adjust not only the battery but also the oil temperature of the reducer, the temperature ranges are different, making it difficult to apply.

[0005] Therefore, an object of the present invention is to provide a temperature control system that can regulate the temperature of a battery, reducer oil, etc. without using a heating device such as a PTC heater. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a temperature control system for an electric vehicle having at least a traction motor as a drive source for the vehicle. The temperature control system includes a first cooling circuit including a first refrigerant pump for circulating a refrigerant, one or more components requiring cooling with a relatively low allowable temperature, and a first heat exchanger into which the refrigerant receives heat from the components; a second cooling circuit including a second refrigerant pump for circulating the refrigerant, one or more components requiring cooling with a relatively high allowable temperature, and a second heat exchanger into which the refrigerant receives heat directly or indirectly from the components; and a bypass circuit branching from the second cooling circuit, passing through a radiator, and rejoining the second cooling circuit. The temperature control system also includes a flow path switching valve provided at a branching or merging point between the bypass circuit and the second cooling circuit, a first temperature acquisition device for acquiring a first refrigerant temperature, which is the temperature of the refrigerant circulating through the first cooling circuit, and a second temperature acquisition device for acquiring a second refrigerant temperature, which is the temperature of the refrigerant circulating through the second cooling circuit. Furthermore, the temperature adjustment system includes a heat pump system having a circulation path in which a first heat exchanger, a compressor, a second heat exchanger, and an expansion valve are arranged in this order, and a controller that controls the operation of at least the first refrigerant pump, the second refrigerant pump, the compressor, and the flow path switching valve. When the first refrigerant temperature is lower than a first threshold and the second refrigerant temperature is lower than a second threshold that is higher than the first threshold, the controller stops the compressor and operates the first refrigerant pump and the second refrigerant pump to control the first state in which refrigerant circulates in the first cooling circuit and the second cooling circuit. [Effects of the Invention]

[0007] According to the above aspect, it is possible to provide a temperature control system that can adjust the temperature of the battery, the oil for the reducer, and the like, without using a heating device such as a PTC heater. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of a temperature adjustment system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing a control routine during driving. [Figure 3] FIG. 3 is a configuration diagram showing a first state of the temperature adjustment system. [Figure 4] FIG. 4 is a configuration diagram showing a second state of the temperature adjustment system. [Figure 5] FIG. 5 is a configuration diagram showing the second two states of the temperature adjustment system. [Figure 6] FIG. 6 is a configuration diagram showing the temperature adjustment system in a third state. [Figure 7] FIG. 7 is a time chart showing the control routine executed during driving. [Figure 8] FIG. 8 is a flowchart showing a control routine during charging. [Figure 9] FIG. 9 is a configuration diagram showing the fourth state of the temperature adjustment system. [Figure 10] FIG. 10 is a configuration diagram showing the fifth state of the temperature adjustment system. [Figure 11] FIG. 11 is a flowchart showing another example of a control routine during charging. [Figure 12] FIG. 12 is a configuration diagram of a temperature adjustment system according to a first modified example. [Figure 13] FIG. 13 is a configuration diagram of a temperature adjustment system according to a second modified example. [Figure 14] FIG. 14 is a configuration diagram of a temperature adjustment system according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] 1 is a configuration diagram of a temperature adjustment system 1 according to this embodiment. The temperature adjustment system 1 adjusts the temperature of a battery 9, a motor 18, a reduction gear 19, a power conversion device 8, and the like that are mounted on an electric vehicle.

[0011] An electrically powered vehicle is a vehicle that is equipped with at least a motor 18 as a drive source. In other words, it includes not only so-called battery electric vehicles (BEVs) that use only the motor 18 as a drive source, but also so-called hybrid vehicles (HEVs) that use an internal combustion engine as a drive source in addition to the motor 18. Note that the hybrid vehicles referred to here include series, parallel, and series-parallel types. In this embodiment, the case of an electric vehicle will be described.

[0012] The temperature adjustment system 1 includes a first cooling circuit 100 in which a group of components mounted on an electric vehicle having a relatively low allowable temperature are arranged, and a second cooling circuit 101 in which a group of components similarly having a relatively high allowable temperature are arranged. The temperature adjustment system 1 also includes a bypass circuit 102 that branches off from the second cooling circuit 101, passes through a radiator 14, and rejoins the second cooling circuit 101, and a heat pump system 103 that connects the first cooling circuit 100 and the second cooling circuit 101.

[0013] The first cooling circuit 100 includes a first refrigerant pump 6 that circulates a refrigerant within the circuit, a battery 9, a power conversion device 8, a first heat exchanger 4 into which the refrigerant that has received heat from the battery 9 and the power conversion device 8 flows, and a first temperature sensor 7 that detects the temperature of the refrigerant within the first cooling circuit. The power conversion device 8 here includes an inverter, a DC-DC converter, and an on-board charger (OBC). The first heat exchanger 4 exchanges heat between the refrigerant in the first cooling circuit 100 and the refrigerant in the heat pump system 103.

[0014] The second cooling circuit 101 includes a second refrigerant pump 11 that circulates refrigerant within the circuit, an oil cooler 16 that exchanges heat between the refrigerant and oil in an oil cooling circuit including a motor 18 and a reducer 19, a second heat exchanger 5 into which the refrigerant that has passed through the oil cooler 16 flows, and a second temperature sensor 12 that detects the temperature of the refrigerant within the second cooling circuit. An oil pump 17 that circulates the oil is installed in the oil cooling circuit including the motor 18 and the reducer 19. That is, in the second cooling circuit 101, the refrigerant circulated by the second refrigerant pump 11 exchanges heat with the oil heated by the motor 18 and the reducer 19 via the oil cooler 16. The second cooling circuit 101 also includes a reservoir tank 13 that receives excess refrigerant when the refrigerant within the circuit expands as its temperature rises.

[0015] 1, the motor 18 is cooled by circulating the oil of the reducer 19 through the motor 18 as well, but the motor 18 may also be cooled by the refrigerant in the second cooling circuit 101. In other words, the motor 18 may be disposed in the refrigerant flow path before it enters the oil cooler 16. In this case, the refrigerant in the second cooling circuit 101 receives heat directly from the motor 18.

[0016] The branch point of the second cooling circuit 101 and the bypass circuit 102 is located downstream of the second heat exchanger 5, and is provided with a flow path switching valve 15. This flow path switching valve 15 switches whether the refrigerant that has passed through the second heat exchanger 5 circulates directly through the second cooling circuit 101, or branches off from the second cooling circuit 101, passes through the bypass circuit 102, and rejoins the second cooling circuit 101. Note that the flow path switching valve 15 may be located at the junction of the second cooling circuit 101 and the bypass circuit 102, rather than at the branch point.

[0017] The heat pump system 103 comprises a circulation path that is arranged in this order: a first heat exchanger 4, a compressor 2, a second heat exchanger 5, and an expansion valve 3. The compressor 2 can rotate in either the forward or reverse direction. Here, the rotation direction when the refrigerant that has passed through the first heat exchanger 4 is compressed and sent to the second heat exchanger 5 is referred to as the forward direction, and the rotation direction when the refrigerant that has passed through the second heat exchanger 5 is compressed and sent to the first heat exchanger 4 is referred to as the reverse direction.

[0018] The detection signals of the first temperature sensor 7 and the second temperature sensor 12 are sent to the controller 10. Based on these detection signals, the controller 10 controls the first refrigerant pump 6, the second refrigerant pump 11, the compressor 2, the flow path switching valve 15, the power conversion device 8, and the like.

[0019] The controller 10 is composed of a microcomputer equipped with a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 10 can also be composed of multiple microcomputers.

[0020] In this embodiment, of the group of components requiring cooling, i.e., the power conversion device 8, the battery 9, the motor 18, and the reducer 19, the power conversion device 8 and the battery 9 are arranged in the first cooling circuit 100, and the motor 18 and the reducer 19 are arranged in the second cooling circuit 101, but this is not limited to this. A group of components with a relatively low allowable temperature is arranged in the first cooling circuit 100, and a group of components with a relatively high allowable temperature is arranged in the second cooling circuit 1010, but the criteria for whether a temperature is relatively high or low can be set arbitrarily. For example, the motor 18 may be included in the group of components with a relatively low allowable temperature, and the power conversion device 8 may be included in the group of components with a relatively high allowable temperature. Possible variations of these will be described later.

[0021] Of the above-mentioned components, for example, it is known that performance such as charging efficiency of the battery 9 is improved by maintaining the battery 9 at a certain temperature or higher. It is also known that friction in the reducer 19 can be reduced by maintaining the oil at a certain temperature or higher. On the other hand, it is known that the battery 9, the reducer 19, and even the power conversion device 8 and the motor 18 suffer performance degradation when their temperatures become excessively high. Therefore, the controller 10 controls the temperature adjustment system 1 as described below to keep the temperatures of the in-vehicle components within an appropriate range.

[0022] [Control during driving] 2 is a flowchart showing a control routine executed by the controller 10 while the vehicle is running. The control routine is executed based on a program stored in the controller 10 in advance.

[0023] When the vehicle starts traveling, the temperature adjustment system 1 is controlled to a first state (step S100). The first state is a state in which the compressor 2 is stopped, the first refrigerant pump 6 and the second refrigerant pump 11 are operating, and the refrigerant circulates in each of the first cooling circuit 100 and the second cooling circuit 101, as shown in Fig. 3 .

[0024] In this state, in step S101, the controller 10 determines whether the first refrigerant temperature T1 detected by the first temperature sensor 7 is lower than the first threshold value Tth1, and if it is lower, executes the process of step S101, otherwise executes the process of step S106. The first threshold value is a temperature determined based on the temperature at which the group of components arranged in the first cooling circuit 100, in this case the power conversion device 8 and the battery 9, can exhibit the desired performance and the allowable temperature of the group of components.

[0025] In step S102, the controller 10 determines whether the second refrigerant temperature T2 detected by the second temperature sensor 12 is equal to or greater than a second threshold value Tth2, and if it is equal to or greater than the second threshold value Tth2, the controller 10 returns to step S100 to maintain the first state, but if it is not, the controller 10 executes the process of step S103. The second threshold value is a temperature determined based on the temperature at which the components arranged in the second cooling circuit 101, in this case the motor 18 and the reducer 19, can exhibit the desired performance and the allowable temperature of the components.

[0026] That is, when the temperatures of the refrigerant in the first cooling circuit 100 and the second cooling circuit 101 are sufficiently low, such as immediately after startup when the outside air temperature is low, the refrigerant is circulated in each of the first cooling circuit 100 and the second cooling circuit 101. In the first cooling circuit 100, the temperature of the refrigerant rises due to heat generated in association with losses occurring in the power conversion equipment 8 and the battery 9. Similarly, in the second cooling circuit 101, the temperature of the refrigerant rises due to heat generated in the motor 18 and the reducer 19.

[0027] In step S103, the controller 10 controls the temperature adjustment system 1 to a second state. The second state is a state in which the first refrigerant pump 6 and the second refrigerant pump 11 are operated, and the compressor 2 is operated in a direction (reverse direction) in which the refrigerant flows through the second heat exchanger 5, the compressor 2, and the first heat exchanger 4 in that order, thereby transferring heat from the second cooling circuit 101 to the first cooling circuit 100 via the heat pump system 103. That is, the refrigerant that has received heat from the refrigerant in the second cooling circuit 101 in the second heat exchanger 5 is compressed and raised in temperature, and the heated refrigerant is used to raise the temperature of the refrigerant in the first cooling circuit 100 in the first heat exchanger 4.

[0028] Then, in step S104, the controller 10 determines whether the first refrigerant temperature T1 is lower than the first threshold value Tth1, and if so, executes the process of step S105, otherwise executes the process of step S106. In step S105, the controller 10 determines whether the second refrigerant temperature T2 is lower than the fourth threshold value Tth4, and if so, ends the current routine, otherwise returns to step S103 and maintains the second state. The fourth threshold value Tth4 is a temperature higher than the first threshold value Tth1 and lower than the second threshold value Tth2, and serves as hysteresis for the second threshold value Tth2.

[0029] By the processing of steps S103 to S105 described above, heat is transferred from the second cooling circuit 101 to the first cooling circuit 100 via the heat pump system 103. As a result, while the vehicle is traveling, the second refrigerant temperature T2 of the second cooling circuit 101 can be maintained within or near the temperature range from the second threshold value Tth2 to the fourth threshold value Tth4, and the heat of the second cooling circuit 101 can be used to promote the increase in the first refrigerant temperature T1 of the first cooling circuit 100.

[0030] In step S106, the controller 10 controls the temperature adjustment system 1 to a second two-state state. As shown in Fig. 5 , the second two-state state is a state in which the first refrigerant pump 6 and the second refrigerant pump 11 are operated, and the compressor 2 is operated in a direction (forward direction) in which the refrigerant flows through the first heat exchanger 4, the compressor 2, and the second heat exchanger 5 in that order, thereby transferring heat from the first cooling circuit 100 to the second cooling circuit 101 via the heat pump system 103.

[0031] After control to the second two states, the controller 10 determines in step S107 whether the second refrigerant temperature T2 is lower than the second threshold value Tth2. If it is lower, the controller 10 executes the process of step S108. If it is not lower, the controller 10 executes the process of step S109. Note that the second threshold value Tth2 is higher than the outside air temperature. In step S108, the controller 10 determines whether the first refrigerant temperature T1 is lower than the third threshold value Tth3. If it is lower, the controller 10 returns to step S106 to maintain the second two states. If it is not lower, the controller 10 ends the current routine. The third threshold value Tth3 is a temperature lower than the first threshold value Tth1 and serves as hysteresis for the first threshold value Tth1.

[0032] By the processing of steps S106 to S108 described above, heat is transferred from the first cooling circuit 100 to the second cooling circuit 101 via the heat pump system 103. This prevents the first refrigerant temperature T1 from rising above the first threshold value Tth1, and prevents performance degradation due to excessive temperature rise in the power conversion device 8 and the battery 9. Furthermore, it prevents the second refrigerant temperature T2 from falling excessively, allowing the motor 18 and the reducer 19 to be driven efficiently.

[0033] In step S109, the controller 10 controls the temperature adjustment system 1 to a third state. The third state is a state in which the refrigerant in the second cooling circuit 101 flows through the bypass circuit 102 by controlling the flow path switching valve 15 from the second two-state, as shown in FIG.

[0034] Once the temperature control system 1 is in the third state, the controller 10 determines in step S110 whether the second refrigerant temperature T2 is lower than the fourth threshold value Tth4, and if so, executes the process of step S111, otherwise returns to step S109 to maintain the third state. In step S111, the controller 10 determines whether the first refrigerant temperature T1 is lower than the third threshold value Tth3, and if so, ends the current routine, and if not, returns to step S106 to control the temperature control system 1 to the second two states.

[0035] By the processing of steps S109 to S111 described above, when the second refrigerant temperature T2 is equal to or higher than the second threshold value Tth2, the heat in the second cooling circuit 101 can be released to the outside air via the radiator 14. This makes it possible to suppress a rise in the second refrigerant temperature T2 and to suppress a performance degradation due to an excessive rise in temperature of the components arranged in the second cooling circuit 101.

[0036] Furthermore, since the second refrigerant flows into the radiator 14 at a temperature T2 that is sufficiently higher than the outside air, the heat dissipation efficiency is higher than when the second refrigerant flows through at a lower temperature, which allows the radiator 14 to be made smaller.

[0037] Here, the miniaturization of the radiator 14 will be described in more detail. Components used in an electric vehicle, such as the battery 9, power conversion device 8, motor 18, and reduction gear 19, generate heat due to losses during driving and charging. For this reason, these components are cooled using a refrigerant. However, the refrigerant temperature is at most about 60°C, which is lower than the coolant temperature of a water-cooled internal combustion engine. While it may seem that a small capacity radiator 14 is acceptable if the refrigerant temperature is low, a small difference between the refrigerant temperature and the outside air temperature reduces heat dissipation efficiency, making it necessary to increase the heat dissipation area to achieve the desired cooling effect. As a result, miniaturization of the radiator 14 has been difficult in conventional electric vehicles. In contrast, in the present embodiment, the second refrigerant temperature T2 is raised by heat from the first cooling circuit 100 and flows into the radiator 14 at a temperature sufficiently higher than the outside air temperature, as described above. This improves heat dissipation efficiency and enables miniaturization.

[0038] FIG. 7 is an example of a time chart when the above control routine is executed.

[0039] When the vehicle starts traveling in the first state, the first refrigerant temperature T1 and the second refrigerant temperature T2 rise. Because the amount of heat generated by the motor 18 and the speed reducer 19 is relatively greater than that generated by the power conversion device 8 and the battery 9, the rate at which the second refrigerant temperature T2 rises is higher than that of the first refrigerant temperature T1.

[0040] When the second refrigerant temperature T2 becomes equal to or greater than the second threshold value Tth2 at timing t1, the system switches to the second state. Heat transfer from the second cooling circuit 101 to the first cooling circuit 100 accelerates the increase in the first refrigerant temperature T1 and slows the increase in the second refrigerant temperature T2.

[0041] When the first refrigerant temperature T1 becomes equal to or greater than the first threshold value Tth1 at time t2, the system switches to the second two-state mode. However, because the second refrigerant temperature T2 is equal to or greater than the second threshold value Tth2 at this time, the system immediately switches to the third state. As heat transfers from the first cooling circuit 100 to the second cooling circuit 101 and is then dissipated from the radiator 14, the first refrigerant temperature T1 and the second refrigerant temperature T2 stop rising and begin to decrease.

[0042] When second refrigerant temperature T2 falls below fourth threshold Tth4 at time t3, first refrigerant temperature T1 is equal to or greater than third threshold Tth3, so the system switches to the second two-state mode. Then, when first refrigerant temperature T1 falls below first threshold T1 at time t4, the system switches to the first state. After that, when first refrigerant temperature T1 again falls above first threshold Tth1 at time t5, the system switches to the second two-state mode. At time t6, when second refrigerant temperature T2 falls below second threshold Tth2 and first refrigerant temperature T1 falls below third threshold Tth3, the system returns to the first state.

[0043] As described above, the first refrigerant temperature T1 and the second refrigerant temperature T2 can be raised quickly after the vehicle starts traveling, and an excessive temperature rise can be suppressed.

[0044] [Control during charging] Next, the control of the temperature regulation system 1 during charging will be described.

[0045] When charging the battery 9 by connecting an external charging device to the on-board charger (OBC), it is desirable to charge the battery 9 with high charging efficiency. Therefore, the controller 10 controls the temperature adjustment system 1 as described below to maintain the battery 9 at an appropriate temperature during charging.

[0046] FIG. 8 is a flowchart showing a control routine executed by the controller 10 for controlling the temperature adjustment system 1 during charging.

[0047] In step S200, the controller 10 determines whether the first refrigerant temperature T1 is lower than the first threshold value Tth1. If it is lower, the controller 10 executes the process of step S201, and if not, the controller 10 executes the process of step S202.

[0048] In step S201, the controller 10 controls the temperature control system to a fourth state. As shown in FIG. 9 , in the fourth state, the operation of the first refrigerant pump 6, the second refrigerant pump 11, and the compressor 2 is the same as in the second first state. That is, heat is transferred from the second cooling circuit 101 to the first cooling circuit 100 via the heat pump system 103. However, the method of generating heat in the second cooling circuit 101 differs from the second first state. When an external charging device is connected to the on-board charger (OBC) and the vehicle is charging, the vehicle cannot run, and the motor 18 and the reducer 19 cannot rotate. Therefore, the current command value for the axis (q-axis) corresponding to the torque component of the motor 18 is set to zero, and the current command value for the axis (d-axis) corresponding to the excitation component is alternately switched at a predetermined cycle between a direction that strengthens and a direction that weakens the rotor's magnetic flux. This generates hysteresis loss and continuously flows eddy currents in the rotor, allowing the motor 18 to generate heat without generating torque.

[0049] As described above, by generating heat in the motor 18 and transferring the heat to the first cooling circuit 100 via the heat pump system 103, it is possible to promote the temperature rise of the battery 9.

[0050] On the other hand, if the first refrigerant temperature T1 becomes equal to or higher than the first threshold value Tth1, it is necessary to suppress an excessive rise in the first refrigerant temperature T1. Therefore, the controller 10 executes the processes of steps S202 to S207. The processes of steps S202 to S207 are the same as the processes of steps S106 to S111 described above, and therefore a description thereof will be omitted.

[0051] [Variations] Next, modifications of the above embodiment will be described. The modifications described below also fall within the scope of the present invention, just like the above embodiment. Note that the modifications may be combined as appropriate.

[0052] In the above embodiment, the power conversion device 8 and the battery 9 are arranged in the first cooling circuit 100 as a component group with a relatively low allowable temperature, and the motor 18 and the reducer 19 are arranged in the second cooling circuit 101 as a component group with a relatively high allowable temperature. However, this is merely an example, and the present invention is not limited to this as long as the allowable temperature of the component group in the first cooling circuit 100 is relatively lower than that of the component group in the second cooling circuit 101 when comparing the component group in the first cooling circuit 100 with the component group in the second cooling circuit 101.

[0053] (First Modification) 10 is a configuration diagram of a temperature adjustment system 1 according to a first modification. In this modification, a motor 18, which has a lower allowable temperature than a reducer 19, is arranged in a first cooling circuit 100 as a component with a relatively low allowable temperature. In this case, the control of the temperature adjustment system 1 while the vehicle is traveling is the same as in the above embodiment.

[0054] In this modified example, the control of the temperature regulation system 1 during charging differs from that of the above embodiment. Fig. 11 is a flowchart showing a control routine for controlling the temperature regulation system 1 during charging in the case of the configuration of Fig. 10.

[0055] Steps S300, and S302 to S307 are the same as steps S200, and S202 to S207 in FIG. 8, and therefore the description thereof will be omitted.

[0056] In step S301, the controller 10 controls the temperature adjustment system 1 to a fifth state. In the fifth state, the heat pump system 103 is not operated, and only a current is passed through the axis (d-axis) corresponding to the excitation component to cause the motor 18 to generate heat, and the first refrigerant pump 6 is operated to circulate the refrigerant in the first cooling circuit 100. Note that in the fifth state, the second cooling circuit 101 may or may not circulate the refrigerant.

[0057] The above control allows the heat of the motor 18 to be used to promote the temperature rise of the battery 9, and after the temperature rise, the battery 9 is switched to the second state or the third state, thereby preventing excessive temperature rise.

[0058] (Second Modification) FIG. 12 is a configuration diagram of a temperature control system 1 according to a second modified example. While the above embodiment includes one motor 18 and one reducer 19, a configuration including a first motor 18-1 and a first reducer 19-1 for front-wheel drive and a second motor 18-2 and a second reducer 19-2 for rear-wheel drive may also be used. In this configuration, for example, as shown in FIG. 12, the power conversion device 8 and the battery 9 may be arranged in a first cooling circuit 100, and the motors 18-1 and 18-2, the reducers 19-1 and 19-2, the oil coolers 16-1 and 16-2, and the oil pumps 17-1 and 17-2 may be arranged in a second cooling circuit 101. The control of the temperature control system 1 according to this modified example during driving and charging is the same as in the above embodiment.

[0059] (Third Modification) 13 is a configuration diagram of a temperature adjustment system 1 according to a third modified example. In the above-described embodiment, first modified example, and second modified example, the electrically powered vehicle is a so-called battery electric vehicle (BEV), but the electrically powered vehicle of this modified example is a hybrid vehicle (HEV) equipped with an internal combustion engine 20. The hybrid type may be any of a series type, a parallel type, and a series-parallel type.

[0060] The amount of heat generated by the internal combustion engine 20 is greater than that of the motor 18, the battery 9, etc. In other words, the allowable temperature of the internal combustion engine 20 is relatively high. Therefore, in this modified example, the internal combustion engine 20 is arranged in the second cooling circuit 101. In this case, the refrigerant circulating in the second cooling circuit 101 is what is known as coolant for the internal combustion engine 20. The control of the temperature adjustment system 1 according to this modified example while the vehicle is running and while charging is the same as in the above embodiment.

[0061] 13. In this case, the power generating motor (not shown) may be disposed in either the first cooling circuit 100 or the second cooling circuit 101.

[0062] Alternatively, the internal combustion engine 20 may be disposed in the second cooling circuit 101, and the motor 18 and the reducer 19, which have a lower allowable temperature than the internal combustion engine 20, may be disposed in the first cooling circuit 100. Conversely, the power conversion device 8, which has a higher allowable temperature than the battery 9, may be disposed in the second cooling circuit 101.

[0063] (Fourth Modification) FIG. 14 is a configuration diagram of a temperature control system 1 according to a fourth modification. The configuration of this modification combines the configuration of FIG. 1 according to the above embodiment with a heat pump system 104 for vehicle interior air conditioning. The heat pump system 104 for vehicle interior air conditioning includes an air conditioning compressor 21, a condenser 22, a third heat exchanger 23, an air conditioning expansion valve 24, and an evaporator 25. The refrigerant flow path on the outlet side of the oil cooler 16 of the second cooling circuit 101 branches, and one branch passes through the third heat exchanger 23 and rejoins the second cooling circuit 101. A second flow path switching valve 26 is disposed at the branch point. The operation of the second flow path switching valve 26 is controlled by the controller 10. When the flow path for refrigerant flowing from the second cooling circuit 101 to the third heat exchanger 23 is selected, heat exchange occurs in the third heat exchanger 23 between the refrigerant that has passed through the oil cooler 16 of the second cooling circuit 101 and the refrigerant circulating through the heat pump system 104 for vehicle interior air conditioning.

[0064] In the second state described above, when the refrigerant flows through the third heat exchanger 23 as shown in Fig. 14, heat is transferred from the second cooling circuit 101 to the heat pump system 104 for vehicle interior air conditioning. This improves the heating performance.

[0065] As described above, this embodiment provides a temperature control system 1 for an electric vehicle that includes at least a motor 18 (travel motor) as a drive source for the vehicle. The temperature control system 1 includes a first cooling circuit 100 that includes a first refrigerant pump 6 that circulates a refrigerant, a power conversion device 8, and a battery 9 (one or more components that have a relatively low allowable temperature among the group of components that require cooling), and a first heat exchanger 4 into which refrigerant that has received heat from the power conversion device 8 and the battery 9 flows; a second cooling circuit 101 that includes a second refrigerant pump 11 that circulates the refrigerant, the motor 18, and a speed reducer 19 (one or more components that have a relatively high allowable temperature among the group of components that require cooling), and a second heat exchanger 5 into which refrigerant that has received heat directly or indirectly from the motor 18 and the speed reducer 19 flows; and a bypass circuit 102 that branches off from the second cooling circuit 101, passes through a radiator 14, and rejoins the second cooling circuit 101. The temperature control system 1 also includes a flow path switching valve 15 provided at the branching or confluence point of the bypass circuit 102 and the second cooling circuit 101, a first temperature sensor 7 (first temperature acquisition device) that acquires the first refrigerant temperature, which is the temperature of the refrigerant circulating through the first cooling circuit 100, a second temperature sensor 12 (second temperature acquisition device) that acquires the second refrigerant temperature, which is the temperature of the refrigerant circulating through the second cooling circuit 101, a heat pump system 103 consisting of a circulation path arranged in this order: a first heat exchanger 4, a compressor 2, a second heat exchanger 5, and an expansion valve 3, and a controller 10 that controls the operation of at least the first refrigerant pump 6, the second refrigerant pump 11, the compressor 2, and the flow path switching valve 15.

[0066] As described above, by connecting the first cooling circuit 100 and the second cooling circuit 101 via the heat pump system 103, it is possible to control the temperatures of the following cooling circuits to appropriate ranges, i.e., temperature ranges that allow each component to function efficiently and do not exceed allowable temperatures, thereby extending the vehicle's cruising range.

[0067] In this embodiment, when the first refrigerant temperature is lower than a first threshold and the second refrigerant temperature is lower than a second threshold that is higher than the first threshold, the controller 10 stops the compressor 2 and operates the first refrigerant pump 6 and the second refrigerant pump 11 to control the vehicle to a first state in which the refrigerant circulates through the first cooling circuit 100 and the second cooling circuit 101. As a result, immediately after starting to drive in a low outside air temperature environment, for example, heat generated in the power conversion device 8 and the battery 9 circulates through the first cooling circuit 100, and heat generated in the motor 18 and the reducer 19 circulates through the second cooling circuit 101, thereby accelerating the temperature rise of the components in each cooling circuit.

[0068] In this embodiment, when the first refrigerant temperature is lower than the first threshold value and the second refrigerant temperature is equal to or higher than the second threshold value, the controller 10 operates the first refrigerant pump 6 and the second refrigerant pump 11, and operates the compressor 2 in a direction in which the refrigerant flows in the order of the second heat exchanger 5, the compressor 2, the first heat exchanger 4, and the expansion valve 3, thereby controlling the system to a second state in which heat from the second cooling circuit 101 is transferred to the first cooling circuit 100 via the heat pump system 103. This makes it possible to use the heat from the second cooling circuit 101 to promote temperature rise of the components in the first cooling circuit 100.

[0069] In this embodiment, the controller maintains the second state when the first refrigerant temperature is lower than the first threshold and the second refrigerant temperature is equal to or higher than a fourth threshold that is higher than the first threshold and lower than the second threshold, while controlling the second state to the first state when the first refrigerant temperature is lower than the first threshold and the second refrigerant temperature is lower than the fourth threshold. This allows the refrigerant temperature of the second cooling circuit 101 to be maintained within or near the temperature range between the second threshold and the fourth threshold. Furthermore, by using the fourth threshold that acts as a hysteresis for the second threshold, unnecessarily frequent state switching can be suppressed.

[0070] In this embodiment, when the first refrigerant temperature is equal to or higher than the first threshold, the controller 10 operates the first refrigerant pump and the second refrigerant pump, and operates the compressor 2 in a direction in which the refrigerant flows through the first heat exchanger 4, the compressor 2, the second heat exchanger 5, and the expansion valve 3 in that order, thereby controlling the heat in the first cooling circuit 100 to the second cooling circuit 101 via the heat pump system 103. This cools the refrigerant in the first cooling circuit 100, thereby preventing performance degradation due to an excessive rise in temperature of the components arranged in the first cooling circuit 100. Furthermore, even in a low outside air temperature environment, excessive decreases in the oil temperature of the reducer 19 and the motor 18 can be prevented, allowing the reducer 19 and the motor 18 to be driven efficiently.

[0071] In this embodiment, after controlling to the second two states, the controller 10 maintains the second two states if the second refrigerant temperature is lower than the second threshold and the first refrigerant temperature is equal to or higher than a third threshold that is lower than the first threshold, and controls to the first state if the second refrigerant temperature is lower than the second threshold and the first refrigerant temperature is lower than the third threshold. This prevents excessive temperature drops in the components arranged in the first cooling circuit 100. Furthermore, by using a third threshold that acts as a hysteresis for the first threshold, unnecessarily frequent state switching can be prevented.

[0072] In this embodiment, after controlling to the second two states, when the second refrigerant temperature reaches or exceeds a second threshold value set higher than the outside air temperature, the controller 10 controls from the second two states to a third state in which the refrigerant flows through the bypass circuit 102. This causes the heat in the second cooling circuit 101 to be released into the atmosphere from the radiator 14, thereby suppressing an increase in the temperature of the second refrigerant and suppressing performance degradation of the components arranged in the second cooling circuit 101 due to an excessive increase in temperature.

[0073] Furthermore, heat is dissipated from the radiator 14 in a state where the second refrigerant temperature is sufficiently higher than the outside air temperature, so that the heat dissipation efficiency is improved and the radiator 14 can be made smaller.

[0074] In this embodiment, after controlling to the third state, the controller 10 controls to the second two states when the second refrigerant temperature is higher than the first threshold and lower than a fourth threshold that is lower than the second threshold, and the first refrigerant temperature is equal to or higher than the third threshold. This prevents the second refrigerant temperature from dropping excessively due to heat dissipation from the radiator 14. It also prevents the first refrigerant temperature from dropping excessively due to heat transfer to the second cooling circuit 101. Furthermore, by using the third and fourth thresholds, which act as hysteresis, it is possible to prevent the state from being switched over unnecessarily frequently.

[0075] It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical concept described in the claims. [Explanation of symbols]

[0076] 1 temperature control system, 2 compressor, 3 expansion valve, 4 first heat exchanger, 5 second heat exchanger, 6 first refrigerant pump, 7 first temperature sensor, 8 power conversion device, 9 battery, 10 controller, 11 second refrigerant pump, 12 second temperature sensor, 13 reservoir tank, 14 radiator, 15 flow path switching valve, 16 oil cooler, 17 oil pump, 18 motor, 19 reducer, 100 first cooling circuit, 101 second cooling circuit, 102 bypass circuit

Claims

1. In a temperature control system for an electric vehicle having at least a traction motor as a drive source for the vehicle, a first cooling circuit including a first refrigerant pump that circulates a refrigerant, one or more components that have a relatively low allowable temperature among a group of components that require cooling, and a first heat exchanger into which the refrigerant that has received heat from the components flows; a second cooling circuit including a second refrigerant pump that circulates the refrigerant, one or more components that have a relatively high allowable temperature among a group of components that require cooling, and a second heat exchanger into which the refrigerant that has received heat directly or indirectly from the components flows; a bypass circuit that branches off from the second cooling circuit, passes through a radiator, and rejoins the second cooling circuit; a flow path switching valve provided at a branching or joining portion of the bypass circuit and the second cooling circuit; a first temperature acquisition device that acquires a first refrigerant temperature, which is the temperature of the refrigerant circulating through the first cooling circuit; a second temperature acquisition device that acquires a second refrigerant temperature, which is the temperature of the refrigerant circulating through the second cooling circuit; a heat pump system including a circulation path in which the first heat exchanger, a compressor, the second heat exchanger, and an expansion valve are arranged in this order; a controller that controls operations of at least the first refrigerant pump, the second refrigerant pump, the compressor, and the flow path switching valve; Equipped with when the first refrigerant temperature is lower than a first threshold value and the second refrigerant temperature is lower than a second threshold value that is higher than the first threshold value, the controller stops the compressor and operates the first refrigerant pump and the second refrigerant pump to control the refrigerant to a first state in which the refrigerant circulates in the first cooling circuit and the second cooling circuit.

2. In the temperature control system for an electric vehicle according to claim 1, when the first refrigerant temperature is lower than the first threshold value and the second refrigerant temperature is equal to or higher than the second threshold value, the controller operates the first refrigerant pump and the second refrigerant pump, and operates the compressor in a direction in which the refrigerant flows through the second heat exchanger, the compressor, the first heat exchanger, and the expansion valve in that order, thereby controlling the system to a second state in which heat from the second cooling circuit is transferred to the first cooling circuit via the heat pump system.

3. In the temperature control system for an electric vehicle according to claim 2, and wherein, after controlling the temperature of the refrigerant to the second state, the controller maintains the second state if the first refrigerant temperature is lower than the first threshold value and the second refrigerant temperature is equal to or greater than a fourth threshold value that is higher than the first threshold value and lower than the second threshold value, and controls the temperature of the refrigerant to the first state if the first refrigerant temperature is lower than the first threshold value and the second refrigerant temperature is lower than the fourth threshold value.

4. In the temperature control system for an electric vehicle according to any one of claims 1 to 3, When the first refrigerant temperature is equal to or higher than the first threshold value, the controller operates the first refrigerant pump and the second refrigerant pump, and operates the compressor in a direction in which the refrigerant flows through the first heat exchanger, the compressor, the second heat exchanger, and the expansion valve in that order, thereby controlling the temperature to a second two-state in which heat from the first cooling circuit is transferred to the second cooling circuit via the heat pump system.

5. In the temperature control system for an electric vehicle according to claim 4, and wherein, after controlling to the second two states, the controller maintains the second two states when the second refrigerant temperature is lower than the second threshold value and the first refrigerant temperature is equal to or higher than a third threshold value that is lower than the first threshold value, and controls to the first state when the second refrigerant temperature is lower than the second threshold value and the first refrigerant temperature is lower than the third threshold value.

6. In the temperature control system for an electric vehicle according to claim 4 or 5, and, after controlling the second refrigerant temperature to the second two states, when the second refrigerant temperature becomes equal to or higher than the second threshold value that is set higher than the outside air temperature, the controller controls the second two states to a third state in which the refrigerant flows through the bypass circuit.

7. In the temperature control system for an electric vehicle according to claim 6, After the controller has controlled the temperature to the third state, if the second refrigerant temperature is higher than the first threshold value and lower than a fourth threshold value that is lower than the second threshold value, and the first refrigerant temperature is equal to or higher than a third threshold value that is lower than the first threshold value, the controller controls the temperature to the second two-state state.

Images