vehicle

Abstract

At low temperatures, this suppresses the decrease in insulation between the stator coils of each phase at the coil end. [Solution] A vehicle comprising a motor, an oil supply device that supplies insulating oil with high insulating performance to the coil ends of the motor's stator coils, and a control device that controls the oil supply device, wherein the control device controls the oil supply device so that insulating oil is supplied to the coil ends when the system is stopped. This suppresses the decrease in insulation performance between the stator coils of each phase at the coil ends at low temperatures.

Description

Technical Field

[0001] The present disclosure relates to a vehicle.

Background Art

[0002] Conventionally, as this type of vehicle, there has been proposed one including a motor and an oil supply device that supplies a highly insulating oil to the coil ends of a plurality of stator coils of the motor (see, for example, Patent Document 1). In this vehicle, the insulating oil insulates between the plurality of stator coils at the coil ends. As a result, in this vehicle, the insulation performance between the plurality of stator coils is improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described vehicle, at low temperatures, the viscosity of the insulating oil is high, and the oil supply device cannot ensure a sufficient discharge amount of the insulating oil. In this case, in the above-described vehicle, the insulation performance between the plurality of stator coils at the coil ends deteriorates.

[0005] The main object of the vehicle of the present disclosure is to suppress a decrease in insulation between a plurality of stator coils at the coil ends at low temperatures.

Means for Solving the Problems

[0006] The vehicle of the present disclosure has taken the following means to achieve the above main object.

[0007] The vehicle of the present disclosure A vehicle comprising a motor, an oil supply device that supplies insulating oil with high insulating performance to the coil ends of a plurality of stator coils of the motor, and a control device that controls the oil supply device, The control device controls the oil supply device so that the insulating oil is supplied to the coil end when the system is stopped. This is the gist of it.

[0008] In the vehicle of this disclosure, the oil supply device is controlled so that insulating oil is supplied to the coil ends when the system is stopped. When the system is stopped, it is often after the vehicle has been running, and the temperature of the insulating oil is expected to be high. Therefore, when the system is stopped, the viscosity of the insulating oil is low, and the oil supply device can supply a sufficient amount of insulating oil to the coil ends. At low temperatures, insulating oil has high viscosity and low flow. Therefore, the insulating oil supplied to the coil ends when the system is stopped remains at the coil ends until the system is started again, maintaining a high level of insulation between the multiple stator coils. In this way, by supplying insulating oil to the coil ends when the vehicle's system is stopped, the vehicle can be started with a sufficient amount of insulating oil remaining at the coil ends, even at low temperatures. As a result, the decrease in insulation between the multiple stator coils at the coil ends can be suppressed at low temperatures.

[0009] In the vehicle of this disclosure, if insulating oil is being supplied to the coil end by the oil supply device when the system is stopped, the oil supply device may be controlled so that the supply of insulating oil is stopped even when the system is stopped. When insulating oil is being supplied to the coil end by the oil supply device when the system is stopped, there is already sufficient insulating oil remaining in the coil end when the system is stopped. Therefore, when insulating oil is being supplied to the coil end by the oil supply device when the system is stopped, stopping the supply of insulating oil reduces the energy consumption of the oil supply device. This improves energy efficiency. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing a vehicle according to the embodiment of this disclosure. [Figure 2] This flowchart shows an example of a processing routine executed by the CPU of the ECU. [Figure 3] This is an explanatory diagram illustrating an example of the relationship between the temperature of the hydraulic fluid O and the discharge volume of an electric oil pump. [Figure 4] This is an explanatory diagram illustrating an example of the relationship between the operating time and filling rate of an electric oil pump. [Figure 5] This is an explanatory diagram illustrating an example of the time variation in the dielectric strength between stator coils at the coil end. [Modes for carrying out the invention]

[0011] Embodiments of this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram showing a vehicle according to an embodiment of this disclosure. As shown in the figure, the vehicle 1 is a battery electric vehicle (BEV) that includes, in addition to the ECU 10, a motor MG that drives a pair of drive wheels DW, a battery 2, and an inverter 3.

[0012] The motor MG is a permanent magnet embedded type synchronous generator motor (three-phase AC motor) including a stator S and a rotor R. The stator S includes a stator core and three stator coils, namely a U-phase coil, a V-phase coil, and a W-phase coil. The stator core of the stator S is formed, for example, by stacking multiple electromagnetic steel sheets that have been formed into a substantially annular shape by press working and connecting them in the stacking direction. However, the stator core may also be formed into an annular shape by, for example, pressure molding and sintering ferromagnetic powder. Furthermore, the three stator coils may each be formed by electrically joining multiple segment coils (coil wires), or by electrically joining multiple cassette coils (concentrated winding coils).

[0013] The rotor R includes an annular rotor core RC and a plurality of permanent magnets RM embedded in the rotor core RC to form a plurality of magnetic poles. The rotor core RC is formed, for example, by laminating a plurality of annular electromagnetic steel sheets formed by press working and connecting them in the lamination direction. The rotor core RC also has a plurality of through holes that are spaced apart in the circumferential direction and extend axially. Each permanent magnet RM is placed in the corresponding through hole, and the gap between each permanent magnet RM and the corresponding through hole is filled with a resin such as varnish. Furthermore, the rotor core RC is fixed to a cylindrical rotor shaft by a shrink fit or press fit.

[0014] The motor MG exchanges power with the battery 2 via the inverter 3. The battery 2 is, for example, a lithium-ion secondary battery or nickel-metal hydride secondary battery with a rated output voltage of approximately 400-800V. The inverter 3 drives the motor MG and includes, for example, six transistors and six diodes connected in parallel in opposite directions to each transistor. The inverter 3 is connected to the battery 2 via a system main relay (not shown).

[0015] As shown in Figure 1, the rotor R (rotor shaft) of the motor MG is connected to a pair of drive wheels DW via a reduction mechanism 4, a differential gear 5, and a drive shaft 6. The motor MG, reduction mechanism 4, differential gear 5, and a portion of each drive shaft 6 are housed in a transaxle case 7, forming the transaxle of the vehicle 1. A hydraulic fluid reservoir is defined at the bottom of the transaxle case 7 for storing hydraulic fluid O, which serves as both a lubricating and insulating cooling medium. The hydraulic fluid O, scraped up by the gears in the reduction mechanism 4 and differential gear 5, is supplied to the gears and bearings inside the transaxle case 7 through oil passages and guides (not shown).

[0016] Furthermore, in vehicle 1, a strainer 8 and an electric oil pump 9 are arranged inside the transaxle case 7. The strainer 8 is fixed inside the hydraulic fluid reservoir so that, for example, the suction port located at the bottom opens downwards. The suction port of the electric oil pump 9 is connected to the oil outlet of the strainer 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 or the like (not shown). The hydraulic fluid O that flows out of the oil cooler is supplied to the inside of the rotor R of the motor MG via an oil passage or the like (not shown), and is supplied from inside the rotor R as an insulating cooling medium to insulate and cool the stator S, the stator coils wound around the stator S, the coil ends CE of the stator coils, etc. The hydraulic fluid O has high insulating performance and increases the dielectric strength between the stator coils, i.e., the dielectric strength of the motor MG, thereby enabling higher voltage of the battery 2 and faster switching of the inverter 3.

[0017] The ECU10 includes a computer with a CPU, ROM, RAM, input / output interfaces, various drive circuits, and various logic ICs, and controls (switches control) the inverter 3. The ECU10 receives ignition signals from the ignition switch 12 as input. The ECU10 outputs control signals to the inverter 3 and drive signals to the electric oil pump 9.

[0018] When the vehicle 1 is running, the ECU 10 sets the required torque for the running of the vehicle 1 based on the accelerator opening Acc and the vehicle speed V, sets the required torque as the torque command value Tr* for the motor MG, and controls the inverter 3 to output the torque corresponding to the torque command value (required torque) Tr* within the range of the allowable discharge power Wout to the pair of drive wheels DW. Also, while the vehicle 1 is running, the ECU 10 drives the electric oil pump 9 to supply the working oil O inside the rotor R of the motor MG, and supplies it from inside the rotor R to the stator S, the stator coil wound around the stator S, the coil end CE of the stator coil, etc. The ECU 10 stops driving the electric oil pump 9 when the temperature of the motor MG is low and cooling is not required or when the terminal voltage of the battery 2 is low during the running of the vehicle 1.

[0019] When the ignition switch 12 is turned off, the ECU 10 executes a predetermined system stop process such as turning off a system main relay (not shown) between the inverter 3 and the battery 2 to turn off (stop the system). When the ignition switch 12 is turned on when the system is off, the ECU 10 executes a predetermined system startup process such as turning on the above-mentioned system main relay to turn on (start the system).

[0020] Next, the operation of the vehicle 1 configured in this way, particularly the operation of the electric oil pump 9 when stopping the system, will be described. FIG. 2 is a flowchart showing an example of a processing routine executed by the CPU of the ECU. This routine is executed when the ignition switch 12 is turned off.

[0021] When this routine is executed, the ECU 10 determines whether the electric oil pump 9 is driven when the ignition switch 12 is turned off (S100). When the electric oil pump 9 is not driven, the electric oil pump 9 is driven (S110). By driving the electric oil pump 9, the working oil O is supplied to the coil end CE. Then, the ECU 10 determines whether the system stop process has ended (S120). When the system stop process has not ended, the ECU 10 returns to S110 and continues to drive the electric oil pump 9. When the system stop process ends at S120, the ECU 10 stops driving the electric oil pump 9 (S130) and ends this routine. Here, the reason why the ECU 10 drives the electric oil pump 9 will be explained.

[0022] Figure 3 is an explanatory diagram for explaining an example of the relationship between the temperature of the working oil O (oil temperature) and the discharge amount of the electric oil pump. As shown in the figure, the discharge amount of the electric oil pump 9 is smaller when the oil temperature is low than when it is high. This is based on the fact that when the oil temperature is low, the viscosity of the working oil O becomes higher than when it is high. Figure 4 is an explanatory diagram showing an example of the relationship between the driving time of the electric oil pump and the filling rate. The filling rate is the ratio of the volume of the air in the gap between the stator coils of the coil end CE replaced by the working oil O to the volume of the gap between the stator coils of the coil end CE. As shown in the figure, the filling rate becomes higher when the driving time of the electric oil pump 9 is long than when it is short. This is because when the driving time of the electric oil pump 9 is long, the total amount of the working oil O supplied to the coil end CE becomes larger than when it is short, and more working oil O enters the gap between the stator coils of the coil end CE. Also, the filling rate becomes lower when the oil temperature is low than when it is high. This is based on the fact that when the oil temperature is low, the viscosity of the working oil O becomes higher than when it is high, and it becomes difficult for the working oil O to enter the gap between the stator coils of the coil end CE. Thus, when the oil temperature is low, compared with when it is high, due to the higher viscosity of the working oil O, it becomes difficult for the working oil O to enter the gap between the stator coils of the coil end CE. Therefore, when the oil temperature is low, compared with when it is high, the insulation between the stator coils of the coil end CE deteriorates.

[0023] When the ignition switch 12 is turned off and the system stops, it is often immediately after the vehicle 1 has been driven, so the temperature of the hydraulic fluid O is likely to be high and its viscosity low. Therefore, by driving the electric oil pump 9 when the ignition switch 12 is turned off, a sufficient amount of hydraulic fluid O can be supplied to the coil end CE to maintain the insulation between the stator coils of the coil end CE.

[0024] Figure 5 is an explanatory diagram illustrating an example of the time variation of the dielectric strength between stator coils at the coil ends. In the figure, the solid line shows an example of the time variation of the dielectric strength. The dashed line shows an example of the time variation of 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 charge level (SOC) of the battery 2 decreases. The white arrows show an example of the time variation of the driving state (driving or stopped) of the electric oil pump 9. When the ignition switch 12 is turned on and driving begins at low temperatures (time t0), the motor MG does not need to be cooled at low temperatures, so the ECU 10 controls the electric oil pump 9 to stop. When the electric oil pump 9 stops, the hydraulic fluid O leaks out from the coil end CE due to vibrations during driving and the temperature rise of the motor MG, causing the dielectric strength between the stator coils to decrease and fall below the required dielectric strength. When the motor MG heats up, the ECU 10 controls the electric oil pump 9 to drive in order to cool the motor MG (time t1). When the electric oil pump 9 starts driving, hydraulic fluid O is supplied to the coil end CE, and the hydraulic fluid O enters the gap between the stator coils, increasing the dielectric strength. When the vehicle 1 continues to run and the charge level 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 hydraulic fluid O leaks out from the coil end CE due to vibrations during driving, and the dielectric strength between the stator coils decreases to below the required dielectric strength. Then, when the vehicle stops and the ignition switch 12 is turned off (time t3), the ECU 10 controls the electric oil pump 9 to drive in order to drive it again. As a result, hydraulic fluid O is supplied to the coil end CE, enters the gap between the stator coils, and increases the dielectric strength. When the system off process is completed, the ECU 10 controls the electric oil pump 9 to stop. At this time, the hydraulic fluid O remains between the stator coils at the coil ends CE. Therefore, the insulation between the stator coils of each phase is maintained at a high level until the system is started again.This ensures that when the system is started again, even at low temperatures, sufficient insulating oil remains in the coil end CE, allowing the vehicle 1 to be started. Therefore, at low temperatures, the decrease in insulation between the stator coils of each phase of the coil end CE can be suppressed.

[0025] When the electric oil pump 9 is running in S100, that is, when the electric oil pump 9 is running before the vehicle 1 system is shut down, the ECU 10 stops the electric oil pump 9 (S130) and terminates this routine. When the electric oil pump 9 is running when the system is shut down, that is, when hydraulic fluid O is being supplied to the coil end CE, it is assumed that sufficient insulating oil remains in the coil end CE when the system is shut down. Therefore, when the electric oil pump 9 is running in S100, stopping the electric oil pump 9 reduces energy consumption by the electric oil pump 9. This improves energy efficiency.

[0026] 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 so that hydraulic fluid O is supplied to the coil end CE, thereby suppressing the decrease in insulation between the stator coils of each phase of the coil end CE at low temperatures.

[0027] Furthermore, when the system is stopped, if the electric oil pump 9 is supplying hydraulic fluid O to the coil end CE, energy efficiency can be improved by controlling the electric oil pump 9 so that the supply of hydraulic fluid O is stopped even when the system is stopped.

[0028] In the above embodiment, the ECU 10 determines in S100 whether the electric oil pump 9 is being driven, and if the electric oil pump 9 is being driven, it stops driving the electric oil pump 9 in S130. However, the electric oil pump 9 may be driven immediately without performing the determination in S100.

[0029] In the above-described embodiment, vehicle 1 is a battery electric vehicle (BEV). However, vehicle 1 only needs to be equipped with a motor and an oil supply device that supplies insulating oil with high insulating performance to the coil ends of the motor's stator coil. For example, it may 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) whose onboard battery can be charged with external power.

[0030] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the motor MG corresponds to the "motor", the strainer 8 and the electric oil pump 9 correspond to the "oil supply device", and the ECU 10 corresponds to the "control device".

[0031] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0032] The above describes the forms for implementing this disclosure using embodiments, but this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0033] This disclosure can be used in industries such as vehicle manufacturing. [Explanation of Symbols]

[0034] 1 Vehicle, 2 Battery, 3 Inverter, 4 Reduction mechanism, 5 Differential gear, 6 Drive shaft, 7 Transaxle case, 8 Strainer, 9 Electric 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 comprising a motor, an oil supply device that supplies insulating oil with high insulating performance to the coil ends of the stator coils of the motor, and a control device that controls the oil supply device, The control device controls the oil supply device so that the insulating oil is supplied to the coil end when the system is stopped. vehicle.

2. The vehicle according to claim 1, The control device controls the oil supply device so that the supply of insulating oil is stopped even when the system is stopped, if insulating oil is being supplied to the coil end by the oil supply device when the system is stopped. vehicle.

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