Thermal management system

Abstract

The goal is to prevent the vehicle from stalling due to a dead battery, even if the output of the DC-DC converter is limited. [Solution] The control unit 20 performs suppression control to suppress the operation of at least the electric fan when the DCDC converter included in the ESU 223 is in an output-limited state, the vehicle speed is below a predetermined speed, the temperature of the coolant circulating in the low-temperature circuit 22 is above a predetermined temperature, and the limited output of the DCDC converter is less than the total output of the auxiliary equipment including the electric fan and the air conditioner blower.

Description

Technical Field

[0001] The present disclosure relates to a thermal management system.

Background Art

[0002] In Patent Document 1 below, when the temperature of the cooling water for cooling electric components such as a motor and an inverter rises, the rotational speed of an electric fan for supplying air to a radiator provided in a cooling circuit through which the cooling water circulates is increased to promote the cooling of the cooling water.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A DCDC converter is provided for voltage conversion of a power storage device, and it may be cooled by the same cooling circuit as that of electric components. When the temperature of the cooling water circulating through the cooling circuit rises, the output of the DCDC converter is limited. Therefore, the power consumption of the entire auxiliary machine may exceed the output limit of the DCDC converter, and there is a possibility of falling into a phenomenon such as vehicle stop from battery charge.

[0005] An object of the present disclosure is to avoid vehicle stop from battery charge even when the output of the DCDC converter is limited.

Means for Solving the Problems

[0006] This disclosure relates to a thermal management system for a vehicle equipped with an electrical supply unit including a DC-DC converter that steps down the battery voltage and applies voltage to auxiliary equipment, a radiator, a cooling water circuit through which coolant circulates to cool the electrical supply unit, an electric fan that cools the radiator, an air conditioning system including an air conditioner blower that blows cold and warm air into the passenger compartment, and a control unit that controls the electrical supply unit, the electric fan, and the air conditioner blower. The control unit suppresses the operation of at least the electric fan when the DC-DC converter is in an output-limited state, the vehicle speed is below a predetermined speed, the coolant temperature is above a predetermined temperature, and the limited output of the DC-DC converter is less than the total output of the auxiliary equipment including the electric fan and the air conditioner blower. [Effects of the Invention]

[0007] According to this disclosure, even if the output of the DCDC converter is limited, it is possible to avoid vehicle stalling due to battery drain. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram illustrating the configuration of the thermal management system in this embodiment. [Figure 2] Figure 2 is a diagram illustrating the configuration of the thermal management system in this embodiment. [Figure 3] Figure 3 is a diagram illustrating the arrangement of the heat exchangers shown in Figures 1 and 2. [Figure 4] Figure 4 is a flowchart illustrating the processing flow of the control unit shown in Figure 1. [Figure 5] Figure 5 is a graph illustrating an example of the relationship between the water temperature of the LT radiator and the output limit of the DCDC converter. [Figure 6] Figure 6 is a graph illustrating the inhibitory control shown in Figure 4. [Modes for carrying out the invention]

[0009] This embodiment will now be described with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0010] The following description will use an example of the thermal management system 2 described herein being installed in an electric vehicle (not shown). An electric vehicle is a vehicle equipped with a battery for driving, such as a battery electric vehicle (BEV). An electric vehicle may also be a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a fuel cell electric vehicle (FCEV). However, the use of the thermal management system described herein is not limited to vehicles.

[0011] Figure 1 is a diagram showing an example of the configuration of the thermal management system 2 according to the embodiment of this disclosure. Figure 2 is a diagram showing an example of the configuration of the cooling circuit 29 for Rr included in the thermal management system 2. The thermal management system 2 will be described with reference to Figures 1 and 2.

[0012] The thermal management system 2 comprises a control unit 20, a high-temperature circuit 21, a low-temperature circuit 22, a front (Fr) cooling circuit 23, a battery circuit 24, a five-way valve 25, a water-cooled condenser 26, a chiller 27, a reservoir tank (R / T) 28, and a rear (Rr) cooling circuit 29.

[0013] The control unit 20 is an electronic control unit (ECU) that controls the thermal management system 2. The control unit 20 includes, for example, a processor, memory, storage, and interfaces. The control unit 20 generates control commands based on sensor values ​​obtained from various sensors (such as temperature sensors) included in the thermal management system 2, sensor values ​​obtained from the speed sensor of the vehicle on which the thermal management system 2 is installed, and instruction values ​​based on user operation, and outputs the generated control commands to each part of the thermal management system 2.

[0014] The high-temperature circuit 21 includes an HT (High Temperature) radiator 211, a reservoir tank (R / T) 212, a water pump (W / P) 213, a three-way valve 214, an electric heater 215, a heater core for the front (Fr) 216, and a heater core for the rear (Rr) 217. The high-temperature circuit 21 shares a water-cooled condenser 26 with the Fr cooling circuit 23.

[0015] The heat transfer medium (usually hot water) circulating in the high-temperature circuit 21 flows through either a first path from water pump 213 - water-cooled condenser 26 - three-way valve 214 - electric heater 215 - heater core 216 for Fr, heater core 217 for Rr - reservoir tank 212 - water pump 213, or a second path from water pump 213 - water-cooled condenser 26 - three-way valve 214 - HT radiator 211 - reservoir tank 212 - water pump 213.

[0016] The three-way valve 214 is configured to switch whether the heat transfer medium flowing through the high-temperature circuit 21 also flows through the HT radiator 211. The three-way valve 214 has three ports Pf, Pg, and Ph. Port Pf is an inlet port through which the heat transfer medium flows in from the water-cooled condenser 26. Port Pg is an outlet port through which the heat transfer medium flows out to the electric heater 215, the heater core for Fr 216, and the heater core for Rr 217. Port Ph is an outlet port through which the heat transfer medium flows out towards the HT radiator 211.

[0017] The low-temperature circuit 22 includes an LT (Low Temperature) radiator 221, a reservoir tank (R / T) 28, a sub-radiator 222, an electricity supply unit (ESU: Electricity Supply Unit) 223, a rear power control unit (Rr-PCU: Rear Power Control Unit) 224, a water pump 225, and an oil cooler (O / C) 226. The electricity supply unit 223 is a unit that integrates a charging function and a power distribution function and includes a DCDC converter. A temperature sensor (not shown) is provided in the low-temperature circuit 22. The temperature sensor detects the water temperature of the LT radiator 221 and outputs it to the control unit 20.

[0018] The heat medium (coolant) circulating in the low-temperature circuit 22 flows through the path of the water pump 225 - oil cooler 226 - five-way valve 25 - LT radiator 221 - reservoir tank 28 - sub-radiator 222 - electricity supply unit 223 - rear power control unit 224 - water pump 225.

[0019] The water pump 225 circulates the heat medium in the low-temperature circuit 22 according to a control command from the control unit 20. The electricity supply unit 223 controls the charging and discharging of the battery 242 according to a control command from the control unit 20. The rear power control unit converts the DC power supplied from the battery 242 into AC power according to a control command from the control unit 20 and supplies the AC power to a motor (not shown) built into the transaxle. The oil cooler 226 circulates the lubricating oil of the motor using an electric oil pump (not shown). The electricity supply unit 223, the rear power control unit 224, and the oil cooler 226 are cooled by the heat medium circulating in the low-temperature circuit 22.

[0020] The five-way valve 25 switches the path of the heat medium in the low-temperature circuit 22 and the battery circuit 24 according to a control command from the control unit 20. The LT radiator 221 is arranged near the HT radiator 211 and exchanges heat with the HT radiator 211.

[0021] The five-way valve 25 is connected to the low-temperature circuit 22 and the battery circuit 24. The five-way valve 25 is configured to switch whether the heat medium flowing through the low-temperature circuit 22 flows through the battery 242. The five-way valve 25 is provided with five ports Pa, Pb, Pc, Pd, and Pe. The port Pa is an inlet port through which the heat medium flows from the power supply unit 223, the power control unit 224 for Rr, and the oil cooler 226 of the low-temperature circuit 22. The port Pb is an outlet port through which the heat medium flows toward the bypass path 244 of the battery circuit 24. The port Pc is an outlet port through which the heat medium flows toward the electric heater 241 and the battery 242 of the battery circuit 24. The port Pd is an inlet port through which the heat medium flows from the chiller 27. The port Pe is an outlet port through which the heat medium flows toward the LT radiator 221.

[0022] The cooling circuit 23 for Fr is a refrigeration cycle, and includes a compressor 231, a receiver 232, an expansion valve 233, an evaporator 235 for Fr, an evaporative pressure regulator (EPR) 236, and an expansion valve 234.

[0023] The heat medium (vapor-phase refrigerant or liquid-phase refrigerant) circulating through the cooling circuit 23 for Fr flows through one or both of the first path of the compressor 231 - water-cooled condenser 26 - receiver 232 - expansion valve 233 - evaporator 235 for Fr - evaporative pressure regulator 236 - compressor 231 and the second path of the compressor 231 - water-cooled condenser 26 - receiver 232 - expansion valve 234 - chiller 27 - compressor 231. The chiller 27 is connected to both the cooling circuit 23 for Fr and the battery circuit 24.

[0024] The battery circuit 24 includes a water pump 243, a battery 242, an electric heater 241, a bypass path 244, and a reservoir tank 28. The heat transfer medium (coolant) circulating in the battery circuit 24 flows through one or both of the following paths: a first path from water pump 243 - chiller 27 - five-way valve 25 - electric heater 241 - battery 242 - reservoir tank 28 - water pump 243, and a second path from water pump 243 - chiller 27 - five-way valve 25 - bypass path 244 - reservoir tank 28 - water pump 243.

[0025] The water pump 243 circulates the heat transfer medium within the battery circuit 24 according to control commands from the control unit 20. The chiller 27 cools the heat transfer medium circulating in the battery circuit 24 by heat exchange between the heat transfer medium circulating in the Fr cooling circuit 23 and the heat transfer medium circulating in the battery circuit 24. The battery 242 supplies power for driving to the motor built into the transaxle. The battery 242 may be heated using the electric heater 241 or cooled using the chiller 27. A bypass path 244 is provided so that the heat transfer medium bypasses the electric heater 241 and the battery 242. When the heat transfer medium flows through the bypass path 244, temperature changes in the heat transfer medium due to heat absorption / dissipation between the heat transfer medium and the battery 242 can be suppressed. The reservoir tank 28 maintains the pressure and amount of heat transfer medium in the battery circuit 24 by storing a portion of the heat transfer medium in the battery circuit 24.

[0026] As shown in Figure 2, the rear cooling circuit 29 is a refrigeration cycle that includes a compressor 291, a rear condenser 292, an expansion valve 293, and a rear evaporator 294. The heat transfer medium (gas-phase or liquid-phase refrigerant) circulating in the rear cooling circuit 29 flows through the path of compressor 291 - rear condenser 26 - expansion valve 293 - rear evaporator 294 - compressor 291.

[0027] As shown in Figure 3, the rear condenser 292, the hard radiator 211, and the left radiator 221 are arranged in this order from the front of the vehicle. Airflow is introduced from the front of the vehicle along the arrow in Figure 3 and passes through the rear condenser 292, the hard radiator 211, and the left radiator 221 for heat exchange. An electric fan 30 is provided to facilitate this airflow. The electric fan 30 is driven in response to a control command from the control unit 20.

[0028] Next, the control method of the thermal management system 2 by the control unit 20 will be explained with reference to Figure 4. In step S01, the control unit 20 determines whether the voltage of the DC-DC converter included in the power supply unit 223 is below a predetermined voltage. The predetermined voltage is, for example, 13.5[V]. The determination in step S01 is to determine whether the output of the DC-DC converter is in a limited state.

[0029] If the voltage of the DC-DC converter is below a predetermined voltage (Step S01: YES), the process proceeds to Step S02. If the voltage of the DC-DC converter is not below a predetermined voltage (Step S01: NO), the process proceeds to Step S07.

[0030] In step S02, the control unit 20 determines whether the vehicle speed is below a predetermined speed. The predetermined speed is, for example, 20 km / h.

[0031] If the vehicle speed is below the predetermined speed (step S02: YES), the process proceeds to step S03. If the vehicle speed is not below the predetermined speed (step S02: NO), the process proceeds to step S07.

[0032] In step S03, the control unit 20 determines whether the water temperature of the LT radiator 221 is above a first predetermined temperature. The first predetermined temperature is, for example, 62°C.

[0033] If the water temperature of the LT radiator 221 is above the first predetermined temperature (step S03: YES), the process proceeds to step S04. If the water temperature of the LT radiator 221 is not above the first predetermined temperature (step S03: NO), the process proceeds to step S05.

[0034] In step S05, the control unit 20 determines whether the water temperature of the LT radiator 221 is above a second predetermined temperature. The second predetermined temperature is, for example, 61°C. The second predetermined temperature is set to a value that is lower than and close to the first predetermined temperature.

[0035] If the water temperature of the LT radiator 221 is above the second predetermined temperature (step S05: YES), the process proceeds to step S06. If the water temperature of the LT radiator 221 is not above the second predetermined temperature (step S05: NO), the process proceeds to step S07.

[0036] In step S06, the control unit 20 determines whether the previous determination was to execute suppression control. If the previous determination was to execute suppression control (step S06: YES), the process proceeds to step S04. If the previous determination was not to execute suppression control (step S06: NO), the process proceeds to step S07.

[0037] In step S04, the control unit 20 executes suppression control. In step S07, the control unit 20 executes normal control. Thus, if the determination in step S03 is that the water temperature of the LT radiator 221 is not above the first predetermined temperature, and in step S05 the water temperature of the LT radiator 221 is above the second predetermined temperature (1 degree lower than the first predetermined temperature), the suppression control is continued on the condition that the determination is also suppression control. This is because if the water temperature of the LT radiator 221 remains around the first predetermined temperature, the control will frequently switch between suppression control and normal control, which could cause the output of the electric fan 30 to hunt. Therefore, to avoid hunting as much as possible, the control is given a hysteresis of 1°C.

[0038] Next, suppression control and normal control will be explained. As explained with reference to Figure 3, the rear condenser 292, the hard radiator 211, and the left radiator 221 are arranged in this order from the front of the vehicle. Due to the heat dissipation from the rear condenser 292 and the hard radiator 211, the water temperature of the left radiator 221 is structurally difficult to lower. In particular, when the speed of a vehicle equipped with the thermal management system 2 is low, it becomes difficult to lower the water temperature of the left radiator 221. In order to lower the water temperature of the left radiator 221, the rotation speed of the electric fan 30 may be increased to create airflow, but due to the aforementioned arrangement structure, it may be difficult to lower the water temperature of the left radiator 221 to the target temperature.

[0039] When the water temperature of the LT radiator 221 rises, for example, the DCDC converter included in the electrical supply unit 223 is not adequately cooled, and therefore the output of the DCDC converter is limited. As shown in Figure 5, when the water temperature of the LT radiator 221 exceeds the allowable water temperature (a), the output of the DCDC converter is reduced to below the limit output (c), but the rotational speed of the electric fan 30 remains increased. As a result, the total power consumption of the auxiliary equipment exceeds the limit output (c) of the DCDC converter, consuming the power stored in the battery 242, which may lead to a dead battery and vehicle shutdown.

[0040] In this embodiment, when the vehicle speed and temperature conditions are met, the suppression control in step S04 of Figure 4 is executed to minimize the occurrence of battery drain. The suppression control will be explained with reference to Figure 6. Figure 6(A) shows a graph illustrating an example of the water temperature change when suppression control is performed. Figure 6(B) shows a graph illustrating an example of the output changes of each part when suppression control is not performed. Figures 6(C) and 6(D) show graphs illustrating an example of the output changes of each part when suppression control is performed.

[0041] Figure 6(A) shows the vehicle speed change with a dashed line, and the water temperature of the LT radiator 221 with solid and dashed lines. The water temperature change according to the control example of this disclosure is shown with a dashed line, and the water temperature change according to the comparative example is shown with a solid line.

[0042] As shown in Figure 6(A), after time t1, the water temperature of the LT radiator 221 becomes high, and the electric fan 30 is driven at maximum output. The vehicle speed decreases before time t2, and after time t2, even if the electric fan 30 is driven at maximum output, the water temperature of the LT radiator 221 will exceed the allowable value (a). In the explanation with reference to Figure 4, the allowable value (a) is set to the first predetermined temperature (62 [°C]), and when the water temperature of the LT radiator 221 exceeds this value, the system switches to suppression control. In this suppression control, the output of the electric fan 30 is reduced, and the auxiliary equipment output is suppressed. The water temperature of the LT radiator 221 rises, but it has been confirmed that the actual impact is small.

[0043] On the other hand, if suppression control is not performed, the situation shown in Figure 6(B) occurs. After time t2, the water temperature of the LT radiator exceeds the allowable value (a), so the DCDC converter is driven at the limit output (c). Since suppression control is not performed even after time t2, the output of the electric fan 30 and the air conditioner blower (not shown) is maintained. As a result, the auxiliary equipment output, including the electric fan 30 and the air conditioner blower, exceeds the limit output (c), increasing the possibility of battery drain.

[0044] When an example of suppression control is implemented, the state shown in Figure 6(C) is reached. In the example shown in Figure 6(C), the output of the electric fan 30 is suppressed after time t2. In this example, the output of the electric fan 30 is limited, causing the output of the electric fan 30 and the auxiliary equipment including the air conditioner blower to fall below the limited output (c), so the output of the air conditioner blower is maintained.

[0045] The example shown in Figure 6(D) illustrates a case where limiting the output of the electric fan 30 alone is insufficient. In the example shown in Figure 6(D), the output of both the electric fan 30 and the air conditioner blower is suppressed after time t2. In this example, the output limits on the electric fan 30 and the air conditioner blower cause the total output of the auxiliary equipment, including the electric fan 30 and the air conditioner blower, to fall below the limit output (c).

[0046] The control unit (ECU) and method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit (ECU) and its method described herein may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit (ECU) and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0047] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise.

[0048] [Note] [Note 1] An electrical supply unit 223 including a DC-DC converter that steps down the voltage of the battery 242 and applies voltage to the auxiliary equipment, and an LT radiator 221 are provided, and a low-temperature circuit 22 which is a cooling water circuit through which cooling water circulates to cool the electrical supply unit 223, The electric fan 30 cools the LT radiator 221, Fr cooling circuit 23, which constitutes an air conditioning system including an air conditioner blower that blows cool and warm air into the vehicle interior, A thermal management system 2 for a vehicle equipped with an electrical supply unit 223, an electric fan 30, and a control unit 20 that controls an air conditioner blower, The control unit 20 is The DC-DC converter is in an output limiting state. The vehicle's speed is below the specified speed, The cooling water temperature is above a specified temperature. When the limited output of the DCDC converter is less than the total output of the auxiliary equipment, including the electric fan 30 and the air conditioner blower, At a minimum, suppression control is implemented to suppress the operation of the electric fan 30.

[0049] According to Appendix 1, if the limited output of the DCDC converter is less than the auxiliary output including the electric fan 30 and the air conditioner blower, suppression control is performed by suppressing the operation of at least the electric fan 30. By performing this suppression control, the auxiliary output can be made less than the limited output of the DCDC converter, thereby reducing the occurrence of phenomena such as vehicle stalling due to battery drain. In addition, by prioritizing the suppression control of the electric fan 30 over the air conditioner blower, occupant comfort can be maintained.

[0050] Furthermore, if suppressing the operation of the electric fan 30 alone is insufficient to resolve the situation where the limited output of the DCDC converter is less than the auxiliary output, suppression control can be implemented to suppress the operation of the air conditioner blower in addition to the electric fan 30. In this way, by prioritizing the suppression of the electric fan 30, occupant comfort is ensured, and if there is still a high possibility of battery drain, suppressing the operation of the air conditioner blower as well can more reliably reduce the occurrence of phenomena such as vehicle stalling due to battery drain. [Explanation of Symbols]

[0051] 2: Thermal Management System 20: Control Unit 21: High temperature circuit 22: Low temperature circuit (cooling water circuit) 23: Air conditioning circuit for Fr (air conditioning system) 24: Battery Circuit 25: Five-direction dialect 26: Water-cooled condenser 27: Chiller 28: Reservoir Tank (R / T) 29: Air conditioning circuit for rearview mirror 30: Electric fan

Claims

[Claim 1] An electrical supply unit including a DC-DC converter that steps down the battery voltage and applies it to the auxiliary equipment, and a radiator are provided, and a cooling water circuit through which cooling water circulates to cool the electrical supply unit, An electric fan for cooling the radiator, An air conditioning system including an air conditioner blower that blows cool and warm air into the vehicle interior, A thermal management system for a vehicle equipped with the aforementioned power supply unit, the aforementioned electric fan, and the aforementioned air conditioner blower, The control unit, The DCDC converter is in an output limiting state, The vehicle speed of the aforementioned vehicle is below a predetermined speed, The temperature of the cooling water is above a predetermined temperature, When the limited output of the DC-DC converter is less than the total output of the auxiliary equipment, including the electric fan and the air conditioner blower, A thermal management system that performs suppression control to suppress the operation of at least the electric fan.

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