Thermal management system for electric vehicles

Abstract

This system provides a way to warm up the battery of an electric vehicle even when the motor is not running. [Solution] One embodiment is a thermal management system (1) for an electric vehicle, comprising a drive motor (12), an electric pump (30) for pressurizing a heat transfer medium, a battery (2) for supplying power to the drive motor (12) and the electric pump (30), a first circulation circuit (20B) for the heat transfer medium via the drive motor (12) and the battery (2), and a control device (3). The control device (3) is configured to drive the electric pump (30) to pressurize the heat transfer medium to the first circulation circuit when predetermined low-temperature conditions are met before starting the drive motor (12), thereby warming the heat transfer medium with the electric pump (30) and warming the battery (2) with the heat transfer medium.

Description

Technical Field

[0001] The technology disclosed in the present application relates to a thermal management system for electric vehicles.

Background Art

[0002] Generally, batteries and motors installed in electric vehicles have an appropriate temperature range for normal operation. Conventionally, technologies for controlling the temperature of batteries and motors within an appropriate range through thermal management have been developed. For example, Japanese Patent Application Laid-Open No. 2020-062964 discloses a system that uses oil for lubricating a transaxle for cooling and warming up a battery. This system warms up the battery by supplying oil warmed by heat generated in the transaxle to the battery using an electric oil pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the system disclosed in the above publication, since the waste heat of the transaxle is utilized, the transaxle needs to be operating in order to warm up the battery, and it is not possible to warm up the battery before starting the electric vehicle. It is desirable to provide a system that can warm up the battery even when the driving motor is not started.

Means for Solving the Problems

[0005] One aspect of this technology is a thermal management system for an electric vehicle, comprising a drive motor, an electric pump for pressurizing a heat transfer medium, a battery for supplying power to the drive motor and the electric pump, a first circulation circuit for the heat transfer medium via the drive motor and the battery, and a control device, wherein the control device is configured to drive the electric pump to pressurize the heat transfer medium to the first circulation circuit when predetermined low-temperature conditions are met before the start of the drive motor, thereby warming the heat transfer medium with the electric pump and warming the battery with the heat transfer medium. This makes it possible to warm up the battery before starting the drive motor, and to improve battery performance even in low-temperature environments.

[0006] In some embodiments, the electric pump includes an induction motor. This allows the heat generated in both the stator and rotor within the induction motor to be used as a heat source for the heat transfer medium.

[0007] In some embodiments, the system includes a cooler for cooling the heat transfer medium, a second circulation circuit for the heat transfer medium that bypasses the battery via the drive motor and the cooler, and at least one switching valve for switching between the first and second circulation circuits, wherein the first circulation circuit bypasses the cooler, the drive motor has neodymium magnets, and the control device is further configured to switch to the second circulation circuit via the at least one switching valve if predetermined high-temperature conditions are met before the drive motor is started, drive the electric pump to pressurize the heat transfer medium to the second circulation circuit, cool the heat transfer medium with the cooler, and cool the drive motor with the heat transfer medium. This makes it possible to cool the neodymium magnets of the drive motor before the drive motor is started, and to suppress the deterioration of the drive motor's performance due to high-temperature environments.

[0008] In some embodiments, the control device is further configured to predict the start time of the drive motor based on information obtained from a device owned by the user of the electric vehicle. This improves the efficiency of warming up and cooling the electric vehicle before it starts up. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a thermal management system in which oil flows through a circulation circuit via an electric axle, battery, and oil cooler, as one embodiment of the system. [Figure 2] This diagram shows a thermal management system in which oil flows through a circulation circuit that bypasses the oil cooler via the electric axle and battery. [Figure 3] This diagram shows a thermal management system where oil flows through a circulation circuit that bypasses the battery via the electric axle and oil cooler. [Modes for carrying out the invention]

[0010] [Thermal Management System] Figure 1 shows a thermal management system 1 for a battery 2 and electric axle 10 of an electric vehicle (an electric vehicle in the narrow sense, i.e., a battery electric vehicle) as one embodiment.

[0011] An electric vehicle is equipped with a battery 2 and an electric axle 10. The battery 2 is typically composed of multiple rechargeable secondary battery cells. The electric axle 10 is typically equipped with an inverter 13, a drive motor 12, and a transmission 11. The inverter 13 uses the power from the battery 2 to control the rotation of the drive motor 12. The rotational power of the drive motor 12 is reduced and shifted by the transmission 11 and transmitted to the wheels via the drive shaft. The drive motor 12 can be, for example, a motor using neodymium magnets.

[0012] The thermal management system 1 includes at least one circulation circuit for circulating a heat transfer medium, such as oil, through the housing of the electric axle 10. The thermal management system 1 includes an electric oil pump 30 that uses the power of the battery 2 to pressurize the oil into the circulation circuit. The oil can at least cool the drive motor 12 and lubricate the transmission 11. The electric oil pump 30 can be installed in the same housing as the electric axle 10 or independently of the electric axle 10.

[0013] The thermal management system 1 may include, for example, an oil cooler 40 that cools the oil by heat exchange with coolant or air. The thermal management system 1 includes an oil circulation circuit 20A that passes through the electric axle 10, the battery 2, and the oil cooler 40. This circulation circuit 20A can consist of a common passage 21 that passes through the electric axle 10, a passage 22 that passes through the battery 2, a passage 25 that passes through the oil cooler 40, and passages 24 that connect these. Although not shown, if coolant is used, for example, the coolant can be passed through a circulation circuit that passes through the oil cooler 40 and a radiator provided in the vehicle, and the coolant heated by the oil cooler 40 can be dissipated by the radiator.

[0014] During operation of an electric vehicle, both the electric axle 10 and the battery 2 tend to become hot due to heat generation. In this case, by pressurizing oil and sending it through a circulation circuit 20A that passes through the electric axle 10, the battery 2, and the oil cooler 40, the battery 2 and the drive motor 12 are cooled by the oil. At the same time, the electric oil pump 30 is also cooled, and the transmission 11 is lubricated. The oil is cooled by heat exchange with coolant or air in the oil cooler 40.

[0015] As shown in Figure 2, the thermal management system 1 includes an oil circulation circuit 20B that bypasses the battery 2 via the electric axle 10 and the oil cooler 40. This circulation circuit 20B can be composed of, for example, a common passage 21 that passes through the electric axle 10, a passage 23 that bypasses the battery 2, and a passage 25 that passes through the oil cooler 40. Upstream of the battery 2, there is an electric switching valve 27 that switches between the passage that passes through the battery 2 and the passage that bypasses it.

[0016] The thermal management system 1 includes an oil circulation circuit 20C that passes through the electric axle 10 and battery 2 and bypasses the oil cooler 40. This circulation circuit 20C can consist of, for example, a common passage 21 that passes through the electric axle 10, a passage 22 that passes through battery 2, and a passage 26 that bypasses the oil cooler 40. Upstream of the oil cooler 40, there is another electric switching valve 28 that switches between the passage that passes through the oil cooler 40 and the passage that bypasses it.

[0017] [Electric oil pump] As schematically shown in Figure 1, the electric oil pump 30 comprises a pump motor 31, a control circuit board 34, and a pump unit 32. The pump motor 31 is controlled by the control circuit board 34 and drives the pump unit 32. In one embodiment, the pump unit 32 can be, for example, an internal gear pump. An internal gear pump has an outer (internal) gear and an inner (external) gear that mesh with each other, and oil is pumped through the space between the outer gear 36 and the inner gear 37 by driving either gear.

[0018] The pump motor 31 has a stator 35 and a rotor 36. The electric oil pump 30 can be structured such that oil can be pumped without passing through the narrow air gap between the stator 35 and the rotor 36. For example, the suction port and the discharge port formed in the housing 33 of the electric oil pump 30 can be arranged on the same side of the outer gear 36 and the inner gear 37. By adopting such a structure, the pressure loss of the oil can be reduced. The pump motor 31 can be, for example, an axial gap motor.

[0019] As one embodiment, the pump motor 31 can be an induction motor. Thereby, not only the coil of the stator 35 but also the conductor of the rotor 36 through which the induced current flows generates heat, so that the oil can be efficiently warmed at low temperatures. Further, since the induction motor does not require an expensive magnet for the rotor 36, the cost can be reduced.

[0020] When an induction motor is used, for example, by arranging a conductor with an appropriate shape on the outer gear 36 of the pump section 32, the outer gear 36 can also function as the rotor 36 of the pump motor 31. The outer gear 36 is driven by the induction motor, and the inner gear 37 rotates together with the outer gear 36 to pump the oil. By adopting such a configuration, the shaft and the bearing connecting the rotor 36 and the outer gear 36 can be omitted, and the structure can be simplified. Also, even in a structure that allows the electric oil pump 30 to pass through without passing through the narrow air gap between the stator 35 and the rotor 36 as described above, the outer gear 36 itself generates heat due to the induced current generated in the rotor 36, so that the oil can be warmed.

[0021] [Control device] The heat management system 1 includes a control device 3. The control device 3 includes at least one storage device (memory or recording medium) and at least one processing device (processor), and by executing the program stored in the storage device (memory) with the processing device (processor), various functions including the heat management disclosed in the present application are implemented. Sensors and actuators such as motors and switching valves are connected to the control device 3 via communication means such as communication lines or wireless. Specifically, the control device 3 can be a central computer equipped with a vehicle operating system (OS) or at least one electronic control unit (ECU), a domain control unit (DCU), a zone control unit (ZCU), etc.

[0022] [In the case of cold start] As shown in FIG. 2, when the system is in a low-temperature state before the start of the driving motor 12, such as in winter or at night, the control device 3 performs an operation of warming (warming up) the oil and the battery 2 by utilizing the heat of the electric oil pump 30. Specifically, when a predetermined low-temperature condition is satisfied before the start of the driving motor 12, it is switched to a circulation circuit 20B that bypasses the oil cooler 40 via the battery 2. Then, the electric oil pump 30 is operated to circulate the oil. The temperature of the oil rises due to the heat generated by the pump motor 31 (coil current or induced current) of the electric oil pump 30, and the kinematic viscosity decreases. As a result, the starting load of the driving motor 12 is reduced, and power consumption can be suppressed. On the other hand, the battery 2 is preheated, so that the voltage drop of the battery cells can be suppressed, and the performance of the battery 2 at the start of the driving motor 12 can be improved. The above-mentioned predetermined low-temperature condition can be, for example, that any one of the outside air temperature, the temperature of the battery 2, and the temperature of the driving motor 12 is lower than a predetermined temperature. Although not shown, the control device 3 can obtain these temperatures from temperature sensors installed at places where they touch the outside air, inside the housing of the battery 2, and inside the housing of the driving motor 12, respectively.

[0023] [In the case of hot start] As shown in Figure 3, if the system is in a high-temperature state before starting the traction motor 12, such as during summer or daytime, the control device 3 uses the oil cooler 40 to warm the oil and battery 2. For example, if a predetermined high-temperature condition is met before starting the traction motor 12, the control device 3 switches to a circulation circuit 20C that bypasses the battery 2 via the oil cooler 40. Then, the electric oil pump 30 is operated to circulate the oil and cool the traction motor 12. When the traction motor 12 starts up, the magnet is subjected to a large external magnetic field due to the large current. If the magnet is subjected to a magnetic field that exceeds its coercivity, irreversible demagnetization occurs. In particular, the coercivity of neodymium magnets decreases as the temperature rises. If the traction motor 12 uses neodymium magnets, the occurrence of demagnetization can be suppressed by pre-cooling the neodymium magnets with oil that has passed through the oil cooler 40 as described above. In addition, it is possible to reduce costs by suppressing the amount of expensive dysprosium that is usually added to increase coercivity. The aforementioned predetermined high-temperature conditions can be, for example, a condition where the ambient temperature, the temperature of the battery 2, or the temperature of the drive motor 12 is higher than the predetermined temperature.

[0024] [Control of electric oil pump] The control device 3 can determine the operating parameters of the electric oil pump 30, such as the flow rate, operating time, and termination time, so that either or both the drive motor 12 and the battery 2 reach the optimal temperature before the drive motor 12 starts. For example, the control device 3 can monitor the temperature of the battery 2 and the drive motor 12, and determine or modify the operating parameters of the electric oil pump 30 so that the battery 2 and the drive motor 12 reach the optimal temperature range at or before starting.

[0025] The determination of whether the aforementioned predetermined low-temperature and high-temperature conditions are met must be made before starting the drive motor 12. For this reason, the control device 3 can predict the next start time of the drive motor 12 based on the vehicle start time (i.e., the start time of the drive motor 12) recorded by the control device 3. Furthermore, the above determination can be made well in advance of the predicted start time. In addition, the start time of the drive motor 12 can also be predicted or the predicted start time can be modified based on the time when specific actions by the user on the vehicle are performed, such as remote operation with the vehicle key, approach of the vehicle with the vehicle key (by the vehicle user carrying the key), opening and closing of the vehicle door, or sitting in the driver's seat.

[0026] As shown in Figures 1-3, the control device 3 can also utilize information obtained from a computer device owned by the vehicle user to predict or correct the predicted start time of the driving motor 12. The computer device is, for example, a smart device 50, specifically a smartphone, tablet computer, or wearable device (e.g., a smartwatch) owned or carried by the vehicle user. The control device 3 has a communication interface and is configured to obtain information about the vehicle user's actions via a network 51, such as the internet, from predetermined application software installed on the smart device 50. Information about the vehicle user's actions includes, for example, specific operations on the smart device 50, such as activating the smart device 50 or displaying its screen, and the location of the smart device 50 (or the vehicle user carrying it) (e.g., location information obtained by the smart device 50 via GPS satellites or communication base stations). Based on this information, the control device 3 can predict or correct the predicted start time of the driving motor 12. The control device 3 can also be configured to obtain an active standby instruction entered by the vehicle user on the smart device 50 via the network 51. In this case, the control device 3 can immediately determine, for example, whether the predetermined low-temperature or high-temperature conditions are met based on this standby instruction.

[0027] [For low-temperature fast charging] Even when the battery 2 is rapidly charged before starting, the control device 3 can warm the oil and battery 2 using the heat from the electric oil pump 30 if predetermined low-temperature conditions are met. Specifically, it switches to a circulation circuit 20B that bypasses the oil cooler 40 via the battery 2 (Figure 2). Then, the electric oil pump 30 circulates the oil. As a result, the oil temperature rises due to the heat generated from the rapidly charging battery 2, and its kinematic viscosity decreases. This reduces the starting load on the drive motor 12.

[0028] Although various embodiments have been described above, this technology is not limited to these embodiments, and those skilled in the art can make various substitutions, improvements, and modifications without departing from the spirit of this technology. [Explanation of symbols]

[0029] 1. Thermal Management System 2 batteries 3. Control device 10 Electric Axle 11 Transmission 12. Motor for driving 13 Inverter 20A, 20B, 20C circulation circuit 21 Common passage 22 Passageway through the battery 23. Bypassing the battery 24. Passage connecting the battery and oil cooler. 25 Passage through the oil cooler 26 Passage bypassing the oil cooler 27, 28 Switching valve 30 Electric oil pump 31 Pump motor 32 Pump section 33 Housing 34 Control circuit board 35 stata 36 Rotor and outer gear 37 Inner gear 40 Oil Cooler 50 Smart Devices 51 Network

Claims

1. A thermal management system for electric vehicles, The motor for driving, An electric pump for pressurizing the heat transfer medium, A battery that supplies power to the aforementioned drive motor and the aforementioned electric pump, A first circulation circuit for the heat transfer medium via the drive motor and the battery, The system comprises a control device, and the control device is A thermal management system configured such that, if predetermined low-temperature conditions are met before the start of the drive motor, the electric pump is driven to pump the heat transfer medium into the first circulation circuit, the heat transfer medium is heated by the electric pump, and the battery is heated by the heat transfer medium.

2. A thermal management system according to claim 1, The aforementioned electric pump is a thermal management system having an induction motor.

3. A thermal management system according to claim 1 or 2, A cooler for cooling the aforementioned heat transfer medium, A second circulation circuit for the heat transfer medium that bypasses the battery via the aforementioned drive motor and the aforementioned cooler, It includes at least one switching valve for switching between the first circulation circuit and the second circulation circuit, The first circulation circuit bypasses the cooler, The aforementioned drive motor has a neodymium magnet, The control device further, A thermal management system configured to switch to the second circulation circuit via the at least one switching valve when predetermined high-temperature conditions are met before the start of the drive motor, drive the electric pump to pressurize the heat transfer medium into the second circulation circuit, cool the heat transfer medium with the cooler, and cool the drive motor with the heat transfer medium.

4. A thermal management system according to claim 1 or 2, The control device is further configured as a thermal management system that predicts the start time of the drive motor based on information obtained from a device owned by the user of the electric vehicle.

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