Electric vehicles

Abstract

If oil leakage occurs in the torque converter, the system effectively expels the air that has entered the torque converter and fills the torque converter with hydraulic fluid. [Solution] The electric vehicle comprises an electric motor, a torque converter that transmits power between the rotating shaft and output shaft of the electric motor with torque amplification via hydraulic fluid filled inside, a switching mechanism provided between the output shaft and drive shaft of the torque converter that switches between a forward state, a reverse state and a release state, a pump that supplies hydraulic fluid to the torque converter, and a control unit that, in the event of oil leakage in the torque converter, controls the switching mechanism to the release state and performs oil supply control to supply hydraulic fluid to the torque converter while rotating the electric motor.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle.

Background Art

[0002] Conventionally, an oil leakage prevention device having an air intake prevention means for preventing air intake at the discharge port of a drain oil passage that returns the oil of a torque converter to a transmission has been proposed (see, for example, Patent Document 1). In this device, it is said that by preventing the intake of air from the drain oil passage, oil leakage from the torque converter in a state where the oil supply is stopped can be prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it is difficult to completely prevent oil leakage in the torque converter due to long-term vehicle parking only by preventing air intake.

[0005] The main object of the electric vehicle of the present disclosure is to supply hydraulic oil while expelling the air that has entered the torque converter well and filling the torque converter with hydraulic oil when oil leakage has occurred in the torque converter.

Means for Solving the Problems

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

[0007] The present disclosure provides an electric vehicle equipped with an electric motor, comprising: a torque converter that transmits power between the rotating shaft and the output shaft of the electric motor with torque amplification via hydraulic fluid filled inside; a switching mechanism provided between the output shaft of the torque converter and the drive shaft connected to the drive wheel, which switches between a forward state in which the power transmitted to the output shaft is transmitted to the drive shaft as power for forward movement, a reverse state in which the power transmitted to the output shaft is transmitted to the drive shaft as power for reverse movement, and a release state that cuts off the transmission of power between the output shaft and the drive shaft; a pump that supplies hydraulic fluid to the torque converter; and a control unit that, in the event of oil leakage in the torque converter, controls the switching mechanism to the release state and performs oil supply control to supply hydraulic fluid to the torque converter while rotating the electric motor.

[0008] In the electric vehicle of this disclosure, by controlling the switching mechanism to an open state in the oil supply control, hydraulic fluid can be supplied to the inside of the torque converter while the motor rotates it, without transmitting power from the motor to the drive wheels. The hydraulic fluid supplied to the torque converter adheres to the outer circumference due to the centrifugal force accompanying the rotation of the torque converter, so that the air inside the torque converter is pushed to the inner circumference and expelled out through the gap around the shaft. As a result, the inside of the torque converter can be filled with hydraulic fluid by supplying hydraulic fluid while effectively expelling the air that has entered the torque converter. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the general configuration of the electric vehicle 20 of this disclosure. [Figure 2] This flowchart shows an example of the oil supply control process performed by the main ECU80. [Modes for carrying out the invention]

[0010] Next, we will describe the forms for implementing this disclosure. [Examples]

[0011] Figure 1 is a schematic diagram showing the configuration of the electric vehicle 20 of the present disclosure. The electric vehicle 20 of the present disclosure is a hybrid vehicle and comprises an engine 22, planetary gears 30, motors MG1 and MG2, a battery 40, a torque converter 50, a forward / reverse switching mechanism 60, an electric pump 70, a main ECU 80, and a power supply ECU 90.

[0012] Engine 22 is an internal combustion engine that outputs power using fuel such as gasoline or diesel.

[0013] The planetary gear 30 is configured as a single-pinion type planetary gear mechanism. The rotor of the motor MG1 is connected to the sun gear of the planetary gear 30. The drive shaft 36, which is connected to the drive wheels 39a and 39b via a differential gear 38, is connected to the ring gear of the planetary gear 30. The crankshaft 24 of the engine 22 is connected to the carrier of the planetary gear 30.

[0014] Both motors MG1 and MG2 are configured as synchronous regenerative motors, each having a rotor with embedded permanent magnets and a stator around which three-phase coils are wound. The rotor of motor MG2 is connected to the drive shaft 36 via a torque converter 50, a forward / reverse switching mechanism 60, and a reduction gear 35 in that order.

[0015] The battery 40 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The battery 40 is connected to the power line 42 via the system main relay 41. Inverters 44 and 46, which drive motors MG1 and MG2 by switching switching elements, are connected to the power line 42.

[0016] The torque converter 50 is configured as a fluid transmission device equipped with a torque amplification mechanism and includes a pump impeller 51 connected to the rotor of the motor MG2, a turbine runner 52 positioned opposite the pump impeller 51 and connected to the input shaft 61 of the forward / reverse switching mechanism 60, and a stator 53 positioned between the pump impeller 51 and the turbine runner 52. The torque converter 50 has a lock-up clutch 55, and by engaging and disengaging the lock-up clutch 55, it can either transmit power from the motor MG2 directly to the input shaft 61 of the forward / reverse switching mechanism 60, or transmit power from the motor MG2 to the input shaft 61 of the forward / reverse switching mechanism 60 with amplified torque.

[0017] The forward / reverse switching mechanism 60 includes a planetary gear 62, a forward clutch 64, and a reverse brake 66. The planetary gear 62 is configured as a single-pinion type planetary gear mechanism. The input shaft 61 is connected to the sun gear 62s of the planetary gear 62. The drive shaft 36 is connected to the ring gear 62r via a reduction gear 35. The sun gear 62s (input shaft 61) is connected to the carrier 62c via the forward clutch 64, and the reverse brake 66 is also connected to it.

[0018] The forward / reverse switching mechanism 60 engages the forward clutch 64 and releases the reverse brake 66, thereby integrating the sun gear 62s, ring gear 62r, and carrier 62c into a single rotating body, and transmitting the forward rotational power transmitted from the motor MG2 to the sun gear 62s via the input shaft 61 as power for forward travel from the ring gear 62r to the drive shaft 36 (forward state). Alternatively, the forward / reverse switching mechanism 60 releases the forward clutch 64 and engages the reverse brake 66, fixing the carrier 62c in a non-rotatable state, and reversing the forward rotational power transmitted from the motor MG2 to the sun gear 62s via the input shaft 61 to the ring gear 62r to the drive shaft 36 as power for reverse travel (reverse state). Furthermore, the forward / reverse switching mechanism 60 releases both the forward clutch 64 and the reverse brake 66, thereby allowing the carrier 62c to rotate freely and interrupting the transmission of power between the input shaft 61 and the drive shaft 36 (released state).

[0019] The electric pump 70 is an oil pump powered by electricity supplied from the battery 40 via a DC / DC converter (not shown). The electric pump 70 draws hydraulic fluid from the oil pan 72 formed at the bottom of the transaxle case housing the motors MG1 and MG2 and pumps it to each part. After passing through each part, the hydraulic fluid passes through an oil cooler (not shown) and is returned to the oil pan 72. The electric pump 70 is used to circulate the hydraulic fluid inside and outside the torque converter 50, and to generate the hydraulic pressure necessary for engaging or disengaging the lock-up clutch 55, forward clutch 64, and reverse brake 66. Furthermore, as will be described later, the electric pump 70 is also used to supply (replenish) hydraulic fluid into the torque converter 50 if oil leakage occurs inside the torque converter 50.

[0020] The main ECU 80, although not shown in the diagram, is a microcomputer equipped with a CPU, ROM, RAM, and input / output ports. The main ECU 80 receives signals from various sensors via its input ports. For example, it receives rotational position from rotational position sensors attached to the rotors of motors MG1 and MG2, phase current from current sensors attached to the phase coils of motors MG1 and MG2, rotational speed from a rotational speed sensor attached to the drive shaft 36, and battery current from a current sensor attached to the output terminal of the battery 40. The main ECU 80 calculates the rotational speed of motors MG1 and MG2 based on their rotational positions, and calculates the state of charge (SOC) of the battery 40 based on the integrated battery current. The main ECU 80 also receives input from the shift position sensor 81, the accelerator pedal position from the accelerator pedal position sensor 82, the brake pedal position from the brake pedal position sensor 83, and the vehicle speed from the vehicle speed sensor 84. The main ECU 80 also outputs various control signals via its output ports. For example, the main ECU 80 outputs control signals to the engine 22, drive signals to the system main relay 41, switching control signals to the inverters 44 and 46, drive signals (duty cycle signals) to the electric pump 70, display signals to the display located on the instrument panel in front of the driver's seat, and lights-up signals to the ready lamp 85. The main ECU 80 also outputs control signals to the hydraulic circuit that engages and disengages the lock-up clutch 55, forward clutch 64, and reverse brake 66 using hydraulic fluid from the electric pump 70. The main ECU 80 is connected to the power supply ECU 90 via a communication port, and they exchange signals and data with each other.

[0021] The power supply ECU 90 is responsible for system startup and shutdown control, and although not shown in the diagram, it is equipped with a microcomputer that includes a CPU, ROM, RAM, and input / output ports. The power supply ECU 90 receives input such as the start signal from the start switch 91 and the brake pedal position from the brake pedal position sensor 86.

[0022] When the start switch 81 is turned on and the system startup is requested while the brake pedal 84 is depressed by the driver, the power supply ECU 90 turns on the power relay, supplies power to the main ECU 80, and outputs a start signal (ST signal) to the main ECU 80. The main ECU 80 that receives the ST signal turns off the ready lamp 85 from being off and makes it blink, turns on the system main relay 41, checks the states of various devices, and then turns on the ready lamp 85 as a ready-on (READYON) state indicating that the electric vehicle 20 is in a state where it can run. When the ready lamp 85 is lit, the driver can operate the shift lever 81 to a driving range (D range or R range) and depress the accelerator pedal 84 in the driving range to start (run) the electric vehicle 20.

[0023] The torque converter 50 transmits power through the hydraulic fluid filled inside during torque amplification. Therefore, even when the electric vehicle 20 is started with a relatively large torque immediately after the system is started, the hydraulic fluid in the torque converter 50 is held in a state where the electric pump 70 is stopped so that the torque amplification function of the torque converter 50 can be fully exhibited. Therefore, if the electric vehicle 20 is driven at a normal frequency (frequency of once every one or two days), there is almost no oil leakage in the torque converter 50. However, when the electric vehicle 20 is left unattended for a long time while the system is stopped, the hydraulic fluid in the torque converter 50 leaks out through the fine gaps around the shaft of the torque converter 50, and air may enter the torque converter 50 due to negative pressure. In this state, when the electric vehicle 20 is set to the ready-on state and then attempts to start the electric vehicle 20 with a relatively large torque immediately, torque loss (lost drive) occurs due to insufficient hydraulic fluid in the torque converter 50, giving the driver a sense of discomfort. Therefore, in the electric vehicle 20 of the present disclosure, when the system is started in a state where the electric vehicle 20 has been left unattended for a long time and oil leakage has occurred in the torque converter 50, oil supply control for filling the inside of the torque converter 50 with hydraulic fluid is executed, and then the ready-on state is set. Hereinafter, the details of the oil supply control will be described.

[0024] FIG. 2 is a flowchart showing an example of the oil supply control process executed by the main ECU 80. This process is executed while the ready lamp 85 is blinking after the system startup is requested and the system main relay 41 is turned on in a state where a predetermined period (for example, one week) or more has elapsed since the system was stopped last time.

[0025] When the oil supply control process is executed, the main ECU 80 first starts driving the electric pump 70 (step S100) and releases both the forward clutch 64 and the reverse brake 66 to release the forward / reverse switching mechanism 60 (step S102). Next, the main ECU 80 controls the inverter 46 so that the motor MG2 starts rotating (step S104). Since the pump impeller 51 is rotated by the motor MG2, the hydraulic fluid from the electric pump 70 is supplied to the torque converter 50 while the torque converter 50 is rotating. The hydraulic fluid inside the torque converter 50 adheres to the outer circumference of the torque converter 50 due to the centrifugal force generated by its rotation. Therefore, by continuing to supply hydraulic fluid to the inside of the torque converter 50 while it is rotating, air that has entered the torque converter 50 is collected on its inner circumference and expelled out through the minute gaps around the shaft, and the inside of the torque converter 50 can be filled with hydraulic fluid. Here, both the forward clutch 64 and the reverse brake 66 are disengaged, and the transmission of power between the input shaft 61 and the drive shaft 36 is interrupted. Therefore, even if the motor MG2 is rotated, the drive shaft 36 (drive wheels 39a, 39b) will not be driven.

[0026] Next, the main ECU 80 waits for the elapsed time (rotation time) since the motor MG2 started rotating to be equal to or greater than the threshold time α (step S106). Here, the threshold time α is the time required to fill the torque converter 50 with hydraulic fluid, and is predetermined by experimentation or the like. Alternatively, the main ECU 80 may set the threshold time α by estimating the amount of hydraulic fluid that has leaked out of the torque converter 50 based on the idle time of the electric vehicle 20 (the elapsed time from when the system was last stopped until when the system was requested to start up again) and the temperature of the hydraulic fluid (or ambient temperature). When the rotation time of the motor MG2 is equal to or greater than the threshold time α, the main ECU 80 stops the rotation of the motor MG2 (step S108), engages the forward clutch 64 and releases the reverse brake 66 to set the forward / reverse switching mechanism 60 to the forward state (step S110). Then, the main ECU 80 sets to the ready-on state and lights up the ready lamp 85 (step S112), ending the oil supply control process. As a result, even if the electric vehicle 20 has been left idle for a long period of time and oil has leaked out of the torque converter 50, and the system is required to start, the electric vehicle 20 can be brought into a ready state with the torque converter 50 full of hydraulic fluid. Therefore, even if the driver immediately operates the shift lever to the driving range and presses the accelerator pedal to start with a large torque, the power from the motor MG2 can be properly amplified by the torque converter 50 and transmitted to the drive shaft 36, allowing the electric vehicle 20 to perform to its full potential.

[0027] In the above-described embodiment, the electric vehicle 20 is equipped with an electric pump 70 that supplies hydraulic fluid into the torque converter 50 by electric power. However, instead of the electric pump 70, or in addition to the electric pump 70, a mechanical pump may be provided that supplies hydraulic fluid into the torque converter 50 by the drive of a motor MG2.

[0028] In the embodiment described above, the electric vehicle 20 was configured as a hybrid vehicle equipped with an engine 22 as a power source for driving, but it may also be configured as an electric vehicle without an engine.

[0029] The above describes the forms for implementing this disclosure using examples, but this disclosure is not limited in any way to these examples, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0030] This disclosure is applicable to the electric vehicle manufacturing industry. [Explanation of Symbols]

[0031] 1 Electric vehicle, 36 Drive shaft, 39a, 39b Drive wheels, 50 Torque converter, 60 Forward / reverse switching mechanism, 70 Electric pump, 80 Main ECU.

Claims

[Claim 1] An electric vehicle equipped with an electric motor, A torque converter that transmits power between the rotating shaft and output shaft of the electric motor with torque amplification via the hydraulic fluid filled inside, A switching mechanism is provided between the output shaft of the torque converter and the drive shaft connected to the drive wheel, and switches between a forward state in which the power transmitted to the output shaft is transmitted to the drive shaft as power for forward movement, a reverse state in which the power transmitted to the output shaft is transmitted to the drive shaft as power for reverse movement, and a release state in which the transmission of power between the output shaft and the drive shaft is interrupted. A pump that supplies hydraulic fluid to the torque converter, A control unit that, when oil leakage occurs in the torque converter, controls the switching mechanism to the open state and performs oil supply control to supply hydraulic fluid to the torque converter while rotating the electric motor, An electric vehicle equipped with [a specific feature / equipment].

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