Electric vehicles

Abstract

When the engine is started while there is an oil leak in the torque converter, the torque converter is filled with hydraulic fluid without causing any discomfort to the driver. [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, 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, when a start operation is performed, starts the vehicle and makes it drivable when the start operation is performed while oil has leaked out of the torque converter, after starting the vehicle, 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, and makes it drivable when the start operation is completed and the execution of the oil supply control is completed.

Description

Technical Field

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

Background Art

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

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 by only preventing the intake of air of air. When the vehicle is started in a state where oil leakage has occurred in the torque converter and starts immediately thereafter, there is a risk of torque loss (so-called lost drive) in the torque converter. Therefore, when supplying hydraulic oil into the torque converter, it is desirable not to give the driver a sense of discomfort.

[0005] The main object of the electric vehicle of the present disclosure is to fill the torque converter with hydraulic oil without giving the driver a sense of discomfort when the start operation is performed in a state where 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 interrupts 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, when the electric vehicle is started, starts up, and when the start operation is performed while oil has leaked out of the torque converter, controls the switching mechanism to the release state to rotate the electric motor and performs oil supply control to supply hydraulic fluid to the torque converter, and when the start operation is completed and the execution of the oil supply control ends, the electric vehicle is made drivable.

[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 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. Furthermore, since the vehicle is ready to drive when the oil supply control is completed, the vehicle will not start with oil leaking out of the torque converter, and the driver will not experience the discomfort of torque loss caused by insufficient hydraulic fluid in the torque converter when starting. [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 an oil supply control process. [Figure 3] This is an explanatory diagram showing an example of a filling time table. [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 includes a microcomputer having a CPU, a ROM, a RAM, and input / output ports, although not shown in the figure. The main ECU 80 inputs signals from various sensors via input ports. For example, the main ECU 80 inputs the rotational position from a rotational position sensor attached to the rotors of motors MG1 and MG2, the phase currents from current sensors attached to each phase coil of motors MG1 and MG2, the rotational speed from a rotational speed sensor attached to the drive shaft 36, the battery current from a current sensor attached to the output terminal of the battery 40, and so on. The main ECU 80 calculates the rotational speeds of motors MG1 and MG2 based on the rotational positions of motors MG1 and MG2, and calculates the state of charge (SOC) of the battery 40 based on the integrated value of the battery current. In addition, the main ECU 80 inputs the shift position 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, the vehicle speed from the vehicle speed sensor 84, and so on. Also, the main ECU 80 outputs various control signals via output ports. For example, the main ECU 80 outputs an operation control signal to the engine 22, a drive signal to the system main relay 41, a switching control signal to the inverters 44 and 46, a drive signal (duty signal) to the electric pump 70, a display signal to the display arranged on the instrument panel in front of the driver's seat, a lighting signal to the ready lamp 85, and so on. Further, the main ECU 80 also outputs a control signal to a hydraulic circuit that engages and disengages the lock-up clutch 55, the forward clutch 64, and the reverse brake 66 with the working oil from the electric pump 70. The main ECU 80 is communicably connected to the power supply ECU 90 via a communication port, and exchanges signals and data with each other.

[0021] The power supply ECU 90 is responsible for system startup control and system shutdown control, and includes a microcomputer having a CPU, a ROM, a RAM, and input / output ports, although not shown in the figure. The power supply ECU 90 inputs a start signal from the start switch 91, the brake pedal position from the brake pedal position sensor 86, and so on.

[0022] When the driver depresses the brake pedal 84 and the start switch 81 is turned on, requesting the system to start, the power supply ECU 90 turns on the power relay to supply power to the main ECU 80 and outputs a start signal (ST signal) to the main ECU 80. Upon receiving the ST signal, the main ECU 80 changes the ready lamp 85 from off to blinking, turns on the system main relay 41, checks the status of various devices, and then illuminates the ready lamp 85 to indicate the READY ON state, which means the electric vehicle 20 is ready to run. When the ready lamp 85 is illuminated, the driver can operate the shift lever 81 to the driving range (D range or R range), and then depress the accelerator pedal 84 in the driving range to start (drive) the electric vehicle 20. As described above, the rotor of the motor MG2 is connected to the drive shaft 36 via the torque converter 50 and the forward / reverse switching mechanism 60. Therefore, whether starting the electric vehicle 20 in forward or reverse, the driver can start the electric vehicle 20 with a relatively large torque by pressing the accelerator pedal 84 relatively hard, which amplifies the torque from the motor MG2 with the torque converter 50.

[0023] The torque converter 50 transmits power through the hydraulic oil 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 oil 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, if the electric vehicle 20 is left unattended for a long time while the system is stopped, the hydraulic oil 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. When the electric vehicle 20 is set to the ready-on state in this 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 oil 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 oil 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.

[0025] When the oil supply control process is executed, the main ECU 80 first sets the required hydraulic fluid replenishment time α for 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 the system was requested to start up this time) and the temperature of the hydraulic fluid (or ambient temperature) (step S100). The replenishment time α is set using the replenishment time table illustrated in Figure 3. Here, as shown in the figure, the replenishment time table is set so that the longer the idle time of the electric vehicle 20, the longer the replenishment time α becomes. This is based on the idea that the amount of hydraulic fluid that leaks out of the torque converter 50 increases the longer the idle time of the electric vehicle 20. Also, the replenishment time table is set so that the higher the temperature of the hydraulic fluid (ambient temperature), the longer the replenishment time α becomes. This is based on the idea that the higher the temperature of the hydraulic fluid, the lower the viscous resistance of the hydraulic fluid, making it easier for the hydraulic fluid to leak out of the torque converter 50. Note that if the idle time of the electric vehicle 20 is short (1 or 2 days), there will be almost no oil leakage, so the value of 0 is set for the replenishment time α. Next, the main ECU 80 determines whether the filling time α is 0 (step S102). If the main ECU 80 determines that the filling time α is 0, it determines that no oil has leaked out of the torque converter 50, and engages the forward clutch 64 and releases the reverse brake 66 to set the forward / reverse switching mechanism 60 to the forward position (step S114). Then, the main ECU 80 sets the system to the ready-on state and illuminates the ready lamp 85 (step S116), ending the oil supply control process.

[0026] Meanwhile, when the main ECU 80 determines that the charging time α is not zero, it starts driving the electric pump 70 (step S104) and releases both the forward clutch 64 and the reverse brake 66 to release the forward / reverse switching mechanism 60 (step S106). The main ECU 80 then controls the inverter 46 to start the rotation of the motor MG2 (step S108). 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 continuously supplying 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.

[0027] After the motor MG2 starts rotating, the main ECU 80 waits until the elapsed time (rotation time) since the motor MG2 started rotating is equal to or greater than the filling time α (step S110). When the rotation time of the motor MG2 is equal to or greater than the filling time α, the main ECU 80 determines that the torque converter 50 is filled with hydraulic fluid, stops the rotation of the motor MG2 (step S112), engages the forward clutch 64 and releases the reverse brake 66 to set the forward / reverse switching mechanism 60 to the forward position (step S114). Then, the main ECU 80 sets the system to the ready state and illuminates the ready lamp 85 (step S116), 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 requested to start, the electric vehicle 20 can be brought to the ready state with the torque converter 50 filled with hydraulic fluid. Therefore, even when the driver immediately operates the shift lever to the driving range and presses the accelerator pedal to start the vehicle with a large torque, the power from the motor MG2 can be effectively amplified by the torque converter 50 and transmitted to the drive shaft 36, allowing the electric vehicle 20 to demonstrate its driving performance.

[0028] In the embodiment described above, the electric vehicle 20 was configured as a hybrid vehicle equipped with an engine 22, 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 the electric vehicle is started, initiates the start-up process, and when the start-up is complete, makes the electric vehicle ready to run; when the start-up process is performed while oil leakage has occurred in the torque converter, after initiating the start-up, controls the switching mechanism to the open state to rotate the electric motor and executes oil supply control to supply hydraulic fluid to the torque converter, and when the start-up is complete and the execution of the oil supply control ends, makes the electric vehicle ready to run; An electric vehicle equipped with [a specific feature / equipment].

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