Vehicle

Abstract

The present application aims to suppress a decrease in insulation between stator coils of each phase at a coil end portion at low temperatures. A vehicle includes a motor, an oil supply device that supplies an insulating oil having high insulation performance to a coil end portion of a stator coil of the motor, and a control device that controls the oil supply device, the control device controlling the oil supply device to supply the insulating oil to the coil end portion when a system is stopped. Thus, a decrease in insulation between stator coils of each phase at a coil end portion at low temperatures can be suppressed.

Description

Technical Field

[0001] This invention relates to a vehicle. Background Technology

[0002] Conventionally, vehicles equipped with a motor and an oil supply device that supplies highly insulating oil to the coil ends of multiple stator coils of the motor have been proposed (for example, see Patent Document 1). In this vehicle, insulating oil is used to insulate the multiple stator coils at their coil ends. As a result, the insulation performance between the multiple stator coils is improved in this vehicle.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-81422 Summary of the Invention

[0004] In the aforementioned vehicles, at low temperatures, the viscosity of the insulating oil is high, and the oil supply device cannot ensure a sufficient amount of insulating oil is dispensed. Under these conditions, the insulation performance between multiple stator coils at the coil ends in the aforementioned vehicles is reduced.

[0005] The main objective of the vehicle of the present invention is to suppress the reduction of insulation between multiple stator coils at the coil ends at low temperatures.

[0006] To achieve the aforementioned main objective, the vehicle of the present invention adopts the following solution.

[0007] The vehicle of the present invention comprises: a motor; an oil supply device that supplies insulating oil with high insulating properties to the coil ends of a plurality of stator coils of the motor; and a control device that controls the oil supply device.

[0008] The purpose of the vehicle is that, when the system is stopped, the control device controls the oil supply device to supply the insulating oil to the end of the coil.

[0009] In the vehicle of the present invention, when the system is stopped, the oil supply device is controlled to supply insulating oil to the coil ends. When the system is stopped, it is assumed that the vehicle has been in motion for some time, resulting in a high temperature of the insulating oil. Therefore, when the system is stopped, the viscosity of the insulating oil is low, allowing the oil supply device to supply a sufficient amount of insulating oil to the coil ends. At low temperatures, the viscosity of the insulating oil is high and its fluidity is low. Therefore, the insulating oil supplied to the coil ends when the system is stopped remains at the coil ends until the next system startup, thereby maintaining a high level of insulation between the multiple stator coils. Thus, by supplying insulating oil to the coil ends when the vehicle system is stopped, the vehicle system can be started again when the system is restarted, even at low temperatures, with sufficient insulating oil remaining at the coil ends. As a result, the reduction in insulation between the multiple stator coils at the coil ends at low temperatures can be suppressed.

[0010] In the vehicle of this invention, when the system is stopped, if the oil supply device is supplying insulating oil to the coil end, the oil supply device can be controlled to stop supplying insulating oil even when the system is stopped. When the system is stopped, if the oil supply device is supplying insulating oil to the coil end, sufficient insulating oil remains at the coil end. Therefore, when the system is stopped, if the oil supply device is supplying insulating oil to the coil end, the supply of insulating oil is stopped, thereby suppressing energy consumption based on the oil supply device. This improves energy efficiency. Attached Figure Description

[0011] Figure 1 This is a schematic structural diagram of a vehicle according to an embodiment of the present invention.

[0012] Figure 2 This is a flowchart representing an example of a processing routine executed by the CPU of the ECU.

[0013] Figure 3 This is an explanatory diagram illustrating an example of the relationship between the temperature of the working oil (oil temperature) and the discharge volume of the electric oil pump.

[0014] Figure 4 This is an illustrative diagram illustrating an example of the relationship between the drive time and the filling rate of an electric oil pump.

[0015] Figure 5 This is an explanatory diagram illustrating an example of the time-dependent change in the insulation withstand voltage between the stator coils at the ends of the coil. Detailed Implementation

[0016] Embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram of a vehicle according to an embodiment of the present invention. (Example) Figure 1 As shown, in addition to ECU10, vehicle 1 also includes motor MG that drives a pair of drive wheels DW, battery 2 and inverter 3, and is a battery electric vehicle (BEV).

[0017] The motor MG is a permanent magnet embedded synchronous generator-motor (three-phase AC motor) comprising a stator S and a rotor R. The stator S includes a stator core and three stator coils: the U-phase coil, the V-phase coil, and the W-phase coil. The stator core of the stator S is formed, for example, by stacking multiple electromagnetic steel plates formed into a roughly circular ring shape through stamping and connecting them in the stacking direction. Alternatively, the stator core can be formed into a ring shape, for example, by pressurizing and sintering strongly magnetic powder. Furthermore, the three stator coils can be formed by electrically bonding multiple segmented coils (coil wires) separately, or by electrically bonding multiple ferrule coils (concentrated winding coils) separately.

[0018] The rotor R includes an annular rotor core RC and multiple permanent magnets RM embedded in the rotor core RC to form multiple magnetic poles. The rotor core RC is formed, for example, by stacking multiple electromagnetic steel sheets formed into annular shapes by stamping and connecting them in the stacking direction. Furthermore, multiple through holes extending axially are formed at circumferential intervals on the rotor core RC. Each permanent magnet RM is disposed within a corresponding through hole, and the gap between each permanent magnet RM and the corresponding through hole is filled with resin such as varnish. Moreover, the rotor core RC is fixed to a cylindrical rotor shaft by press-fit or other tight fit.

[0019] Motor MG exchanges power with battery 2 via inverter 3. Battery 2 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery with a rated output voltage of approximately 400-800V. Inverter 3 drives motor MG and includes, for example, six transistors and six diodes connected in anti-parallel to each transistor. Inverter 3 is connected to battery 2 via a system main relay (not shown).

[0020] And, as Figure 1 As shown, the rotor R (rotor shaft) of the motor MG is connected to a pair of drive wheels DW via the reduction mechanism 4, the differential gear 5, and the drive shaft 6. The motor MG, the reduction mechanism 4, the differential gear 5, and a portion of each drive shaft 6 are housed within the transmission drive axle housing 7, forming the transmission drive axle of the vehicle 1. Furthermore, a working oil reservoir is shown at the lower part of the transmission drive axle housing 7, which stores working oil O as a lubricating and insulating cooling medium. The working oil O scraped up by the gears included in the reduction mechanism 4 or the differential gear 5 is supplied to the gears or bearings inside the transmission drive axle housing 7 via oil passages or guides (not shown).

[0021] Furthermore, in vehicle 1, an oil filter 8 and an electric oil pump 9 are disposed within the transmission drive axle housing 7. The oil filter 8 is fixed within the working oil reservoir, for example, with a downward-opening suction port located at the bottom. The suction port of the electric oil pump 9 is connected to the oil outlet of the oil filter 8, and an air-cooled or water-cooled oil cooler (not shown) is connected to the discharge port of the electric oil pump 9 via an oil pipe (not shown). The working oil O flowing from the oil cooler is supplied to the interior of the rotor R of the motor MG via an oil passage (not shown), and is supplied as an insulating cooling medium to insulate and cool the stator S or the stator coils wound around the stator S, and the coil ends CE of the stator coils from inside the rotor R. The working oil O has high insulation performance, increasing the insulation withstand voltage between the stator coils, i.e., the insulation withstand voltage of the motor MG, thereby enabling high-voltage operation of the battery 2 and high-speed switching of the inverter 3.

[0022] ECU10 includes a computer or various drive circuits and logic ICs with CPU, ROM, RAM, input / output interfaces, etc., and controls inverter 3 (switching control). Ignition signals from ignition switch 12 and other components are input to ECU10. ECU10 outputs control signals to inverter 3 or drive signals to electric fuel pump 9, etc.

[0023] While vehicle 1 is in motion, ECU 10 sets the required torque for the vehicle's operation based on the throttle opening (Acc) and vehicle speed (V). This required torque is set as the torque command value Tr* for motor MG. ECU 10 controls inverter 3 to output the torque corresponding to the torque command value (required torque) Tr* to a pair of drive wheels DW within the allowable discharge power Wout range. Furthermore, while vehicle 1 is in motion, ECU 10 drives electric oil pump 9 to supply working oil O to the rotor R of motor MG, and from the rotor R to the stator S, the stator coil wound around the stator S, the coil ends CE of the stator coil, etc. While vehicle 1 is in motion, when the temperature of motor MG is low and cooling is not required, or when the voltage between the terminals of battery 2 is low, ECU 10 drives electric oil pump 9 to stop.

[0024] When the ignition switch 12 is off, the ECU 10 performs the prescribed system stop process, such as shutting down the system main relay (not shown) between the inverter 3 and the battery 2, and enters the ready-to-stop state (stop system). If the ignition switch 12 is on when entering the ready-to-stop state, the ECU 10 performs the prescribed system start process, such as turning on the aforementioned system main relay, and enters the ready-to-start state (start system).

[0025] Next, the operation of the vehicle 1 configured in this way will be explained, especially the operation of the electric oil pump 9 when the system is stopped. Figure 2 This is a flowchart representing the processing routine executed by the ECU's CPU. This routine is executed when the ignition switch 12 is off.

[0026] When this routine is executed, ECU 10 determines whether the electric fuel pump 9 is being driven when the ignition switch 12 is turned off (S100). If the electric fuel pump 9 is not being driven, it is driven (S110). By driving the electric fuel pump 9, working oil O is supplied to the coil terminal CE. Then, ECU 10 determines whether the system stop process has ended (S120). If the system stop process has not ended, ECU 10 returns to S110 and continues to drive the electric fuel pump 9. Then, when the system stop process ends in S120, ECU 10 stops the drive of the electric fuel pump 9 (S130) and ends this routine. Here, the reason for ECU 10 driving the electric fuel pump 9 will be explained.

[0027] Figure 3This is an explanatory diagram illustrating an example of the relationship between the temperature of the working oil O (oil temperature) and the discharge volume of the electric oil pump. As shown in the diagram, the discharge volume of the electric oil pump 9 is less when the oil temperature is low than when the oil temperature is high. This is because the viscosity of the working oil O is higher at lower oil temperatures compared to higher oil temperatures. Figure 4 This is an explanatory diagram illustrating an example of the relationship between the drive time of the electric oil pump and the fill rate. The fill rate is the ratio of the volume of air in the gap replaced by working oil O to the volume of the gap between the stator coils at the coil end CE. As shown in the diagram, the fill rate is higher when the drive time of the electric oil pump 9 is longer than when the drive time is shorter. This is because, when the drive time of the electric oil pump 9 is longer, the total amount of working oil O supplied to the coil end CE is greater than when the drive time is shorter, and more working oil O enters the gap between the stator coils at the coil end CE. Furthermore, the fill rate is lower when the oil temperature is low than when the oil temperature is high. This is because, at low oil temperatures, the viscosity of the working oil O is higher than at high oil temperatures, making it difficult for the working oil O to enter the gap between the stator coils at the coil end CE. Thus, at low oil temperatures, the insulation between the stator coils at the coil end CE is reduced compared to when the oil temperature is high.

[0028] When the ignition switch 12 is turned off and the system stops, since this often happens immediately after the vehicle 1 has been driven, the working oil O is assumed to be at a high temperature and low viscosity. Therefore, when the ignition switch 12 is turned off, the electric oil pump 9 can be driven to supply a sufficient amount of working oil O to the coil end CE to maintain the insulation between the stator coils of the coil end CE.

[0029] Figure 5This is an explanatory diagram illustrating an example of the time-dependent change in the insulation withstand voltage between the stator coils at the coil ends. In the diagram, solid lines represent an example of the time-dependent change in insulation withstand voltage. A dashed line represents an example of the time-dependent change in the stress (corresponding to the voltage difference) applied to the stator coils due to the voltage difference between the stator coils. The stress decreases as the state of charge (SOC) of the battery 2 decreases. Hollow arrows represent an example of the time-dependent change in the driving state (driving or stopping) of the electric oil pump 9. When the ignition switch 12 is turned on at low temperature and driving begins (time t0), since the motor MG is at a low temperature and does not require cooling, the ECU 10 controls the electric oil pump 9 to stop. When the electric oil pump 9 stops, working oil O is discharged from the coil end CE due to vibration during driving or the heating of the motor MG, causing the insulation withstand voltage between the stator coils to decrease below the required withstand voltage. When the motor MG heats up, the ECU 10 controls the electric oil pump 9 to drive the electric oil pump 9 to cool the motor MG (time t1). The electric oil pump 9 starts driving, supplying working oil O to the coil end CE. The working oil O enters the gap between the stator coils, increasing the insulation withstand voltage. When the vehicle 1 continues driving and the state of charge (SOC) of the battery 2 decreases (time t2), the ECU 10 controls the electric oil pump 9 to stop. When the electric oil pump 9 stops, the working oil O is discharged from the coil end CE due to vibrations during driving, causing the insulation withstand voltage between the stator coils to decrease below the required withstand voltage. Then, when driving stops and the ignition switch 12 is turned off (time t3), the electric oil pump 9 is controlled to start driving again. This allows the working oil O to be supplied to the coil end CE and enter the gap between the stator coils, increasing the insulation withstand voltage. When the system shutdown process ends, the ECU 10 controls the electric oil pump 9 to stop. At this time, the working oil O remains between the stator coils at the coil end CE. Therefore, a high insulation state between the stator coils of each phase is maintained until the next system start-up. Therefore, when starting the system again, even at low temperatures, the vehicle 1 can still be started with sufficient insulating oil remaining at the coil terminals CE. This prevents the reduction in insulation between the stator coils of each phase at the coil terminals CE at low temperatures.

[0030] When the electric oil pump 9 is running in S100, that is, when the electric oil pump 9 is running before stopping the system of vehicle 1, ECU 10 stops the running of the electric oil pump 9 (S130) and ends the routine. When the system is stopped, if the electric oil pump 9 is running, that is, when it is supplying working oil O to the coil end CE, it is assumed that sufficient insulating oil remains at the coil end CE when the system is stopped. Therefore, when the electric oil pump 9 is running in S100, stopping the running of the electric oil pump 9 suppresses energy consumption based on the electric oil pump 9. As a result, energy efficiency can be improved.

[0031] According to the vehicle 1 of this embodiment described above, when the system of the vehicle 1 is stopped, the electric oil pump 9 is driven to supply working oil O to the coil end CE, thereby suppressing the reduction of insulation between the stator coils of each phase at the coil end CE at low temperature.

[0032] Furthermore, when the system is stopped, if the electric oil pump 9 is supplying working oil O to the coil end CE, the electric oil pump 9 is controlled to stop supplying working oil O even when the system is stopped, thereby improving energy efficiency.

[0033] In the above embodiment, ECU10 determines in S100 whether the electric oil pump 9 is being driven. If the electric oil pump 9 is being driven, it stops driving the electric oil pump 9 in S130. However, it is also possible to drive the electric oil pump 9 immediately without performing the determination in S100.

[0034] In the above embodiment, vehicle 1 is a pure electric vehicle (BEV). However, vehicle 1 only needs to have a motor and an oil supply device that supplies highly insulating oil to the coil ends of the motor's stator coil. For example, it can be a fuel cell electric vehicle (FCEV) equipped with a fuel cell, a hybrid electric vehicle (HEV) equipped with an engine and a motor, or a plug-in hybrid electric vehicle (PHEV) capable of charging the on-board battery with external power.

[0035] The correspondence between the main elements of the implementation method and the main elements of the invention described in the solution to the problem section is explained. In the implementation method, motor MG corresponds to "motor", oil filter 8 and electric oil pump 9 correspond to "oil supply device", and ECU10 corresponds to "control device".

[0036] Furthermore, the correspondence between the main elements of the implementation method and the main elements of the invention described in the "Solution to Solve the Problem" column is merely an example of how the implementation method is used to carry out the invention described in the "Solution to Solve the Problem" column, and therefore does not limit the elements of the invention described in the "Solution to Solve the Problem" column. That is, the interpretation of the invention described in the "Solution to Solve the Problem" column should be based on the description in that column; the implementation method is simply a specific example of the invention described in the "Technology to Solve the Problem" column.

[0037] The present invention has been described above using embodiments, but the present invention is not limited to such embodiments and can of course be implemented in various ways without departing from the spirit of the present invention.

[0038] This invention can be applied to industries such as vehicle manufacturing.

[0039] Symbol Explanation

[0040] 1-Vehicle, 2-Battery, 3-Inverter, 4-Reduction mechanism, 5-Differential gear, 6-Drive shaft, 7-Transmission drive axle housing, 8-Oil filter, 9-Electronic oil pump, 10-Electronic control unit (ECU), CE-Coil end, MG-Motor, R-Rotor, RC-Rotor core, RM-Permanent magnet, S-Stator.

Claims

1. A vehicle, characterized in that, It comprises: a motor; an oil supply device that supplies high-insulation-performance insulating oil to the coil ends of the stator coils of the motor; and a control device that controls the oil supply device. When the system is stopped, the control device controls the oil supply device to supply the insulating oil to the end of the coil.

2. The vehicle according to claim 1, characterized in that, When the system is stopped, if the oil supply device is supplying insulating oil to the coil end, the control device will still control the oil supply device to stop supplying insulating oil even when the system is stopped.

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