Electric vehicle

Abstract

To provide a technique capable of more surely suppressing torsional resonance generated in a drive unit.SOLUTION: An electric vehicle includes: a drive unit including a wheel, a motor that drives the wheel, and a disconnect mechanism provided in a torque transmission path between the motor and the wheel; and a control device that controls the disconnect mechanism. The disconnect mechanism can selectively realize a connected state in which a torque transmission path is connected, a disconnected state in which the torque transmission path is disconnected, and a standby state which is a state between the connected state and the disconnected state. The control device switches the disconnect mechanism from the connected state to the standby state when the electric vehicle travels on the wavy road, and switches the disconnect mechanism from the standby state to the disconnected state when the electric vehicle is suddenly braked after the disconnect mechanism is switched to the standby state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an electric vehicle. [Background technology]

[0002] Patent Document 1 discloses an electric vehicle including a drive unit having wheels, a motor for driving the wheels, and a disconnection mechanism provided in a torque transmission path between the motor and the wheels, and a control device for controlling the disconnection mechanism. The disconnection mechanism can selectively realize a connected state in which the torque transmission path is connected, and a disconnected state in which the torque transmission path is disconnected. When the electric vehicle travels on an uneven road and suddenly brakes, the control device switches the disconnection mechanism from the connected state to the disconnected state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-151325 Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric vehicle, if sudden braking is applied while the vehicle is traveling on an uneven road, the wheels may repeatedly spin and contact the ground, which can cause torsional resonance in the drivetrain from the motor to the wheels. In order to avoid or suppress such torsional resonance, the electric vehicle of Patent Document 1 is configured to switch the disconnect mechanism from a connected state to a disconnected state when sudden braking is applied while the vehicle is traveling on an uneven road. However, there is still a risk of torsional resonance occurring in the drivetrain during the period between the time the electric vehicle is suddenly braked and the time the disconnect mechanism is switched from a connected state to a disconnected state.

[0005] This specification provides a technique that can more reliably suppress torsional resonance occurring in the drivetrain. [Means for solving the problem]

[0006] The electric vehicle disclosed herein may include a drive unit having wheels, a motor that drives the wheels, and a disconnection mechanism provided in a torque transmission path between the motor and the wheels, and a control device that controls the disconnection mechanism. The disconnection mechanism may be capable of selectively realizing a connected state in which the torque transmission path is connected, a disconnection state in which the torque transmission path is disconnected, and a standby state that is a state between the connected state and the disconnection state. The control device may switch the disconnection mechanism from the connected state to the standby state when the electric vehicle travels on an uneven road, and after switching the disconnection mechanism to the standby state, switch the disconnection mechanism from the standby state to the disconnection state when the electric vehicle suddenly brakes.

[0007] According to the above configuration, when the electric vehicle travels on an uneven road, the disconnect mechanism is switched from the connected state to the standby state. Therefore, when the electric vehicle is suddenly braked after that, the disconnect mechanism is switched to the disconnected state relatively quickly. Therefore, torsional resonance occurring in the drivetrain can be more reliably suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 2 shows a schematic configuration of an embodiment of an electric vehicle 2. [Figure 2] FIG. 10 shows a flowchart of a disconnection process. DETAILED DESCRIPTION OF THE INVENTION

[0009] An electric vehicle 2 will be described with reference to Fig. 1. The electric vehicle 2 is a battery electric vehicle, a hybrid electric vehicle, a fuel cell electric vehicle, or a plug-in hybrid electric vehicle.

[0010] The electric vehicle 2 includes a vehicle body 10 and a pair of wheels 12r, 12l provided on the vehicle body 10. In this embodiment, the wheels 12r, 12l are a pair of front wheels provided on the front part of the vehicle body 10, but may be a pair of rear wheels.

[0011] The electric vehicle 2 further includes a battery 20 and a drive unit 22. The battery 20 has a plurality of secondary battery cells and is configured to be repeatedly chargeable and dischargeable. The secondary battery cells referred to here are not particularly limited, and may be, for example, lithium-ion battery cells or nickel-metal hydride battery cells. The drive unit 22 includes a motor 24, a transmission mechanism 26, a disconnect mechanism 28, and a differential mechanism 30. The motor 24 is connected to the battery 20. The motor 24 can function not only as a prime mover driven by power supplied from the battery 20, but also as a generator for regenerative braking of the wheels 12r, 12l. The transmission mechanism 26, the disconnect mechanism 28, and the differential mechanism 30 are provided in a torque transmission path 32 between the wheels 12r, 12l and the motor 24. The transmission mechanism 26 is connected to the motor 24. The differential mechanism 30 is connected to the wheels 12r, 12l. The disconnect mechanism 28 is disposed between the transmission mechanism 26 and the differential mechanism 30 .

[0012] The drive unit 22 may be a single-shaft planetary eAxle that uses a planetary gear mechanism, or may be a three-shaft eAxle.

[0013] The disconnect mechanism 28 includes a clutch and an actuator that activates the clutch. For example, the clutch is a friction clutch or a dog clutch. For example, the actuator is a motor-type, electromagnetic, or hydraulic actuator. The disconnect mechanism 28 can selectively realize a connected state in which the torque transmission path 32 is connected, a disconnected state in which the torque transmission path 32 is disconnected, and a standby state that is a state between the connected state and the disconnected state. When a friction clutch is used as the clutch, a half-clutch state is an example of the "standby state." Furthermore, when a dog clutch is used as the clutch, the state immediately before switching from the connected state to the disconnected state is an example of the "standby state."

[0014] The electric vehicle 2 further includes a control device 40 and sensors 42. The control device 40 is a so-called ECU. The control device 40 is configured using a computer device and has a memory that stores various control programs, a processor that executes those control programs, and the like. The control device 40 acquires sensor signals from sensors 42 attached to the electric vehicle 2 and controls the operation of each component of the electric vehicle 2. The sensors 42 include an accelerator pedal sensor, a brake pedal sensor, a brake oil pressure sensor, a wheel speed sensor, a motor rotation speed sensor, an image sensor, a gyro sensor, and the like.

[0015] (Disconnection process; Figure 2) The disconnection process executed by the control device 40 of the electric vehicle 2 will be described with reference to Fig. 2. When the disconnection process is started, the disconnection mechanism 28 is in the connected state.

[0016] In S10, the control device 40 determines whether the electric vehicle 2 is traveling on an undulating road. As an example, the control device 40 may use an image sensor to determine whether the electric vehicle 2 is traveling on an undulating road, or may use a gyro sensor to determine whether the electric vehicle 2 is traveling on an undulating road. If the control device 40 determines that the electric vehicle 2 is traveling on an undulating road (YES in S10), the control device 40 proceeds to S12. On the other hand, if the control device 40 determines that the electric vehicle 2 is not traveling on an undulating road (NO in S10), the control device 40 waits in S10.

[0017] In S12, the controller 40 switches the disconnect mechanism 28 from the connected state to the standby state.

[0018] The process content of S20 is the same as the process content of S 10. If the determination in S20 is NO, the control device 40 proceeds to S22, and if the determination in S20 is YES, the control device 40 proceeds to S30.

[0019] In S22, the controller 40 switches the disconnect mechanism 28 from the standby state to the connected state.

[0020] In S30, the control device 40 determines whether the electric vehicle 2 is braking suddenly. As an example, the control device 40 determines whether the electric vehicle 2 is braking suddenly by using the rate of change of the brake oil pressure, the rate of change of the brake pedal stroke, etc. If the control device 40 determines that the electric vehicle 2 is braking suddenly (YES in S30), the control device 40 proceeds to S32. On the other hand, if the control device 40 determines that the electric vehicle 2 is not braking suddenly (NO in S30), the control device 40 returns to S20.

[0021] In S32, the control device 40 switches the disconnect mechanism 28 from the standby state to the disconnect state, thereby disconnecting the torque transmission path 32 between the wheels 12r, 12l and the motor 24.

[0022] The processing content of S34 is the same as the processing content of S30. If the control device 40 determines NO in S34, it proceeds to S36, and if the control device 40 determines YES in S34, it waits in S34. Note that the control device 40 may also determine YES in S34 if a predetermined time has elapsed since it determined that the electric vehicle 2 was not suddenly braked.

[0023] In S36, the controller 40 switches the disconnection mechanism 28 from the disconnected state to the connected state. When S36 ends, the controller 40 returns to S10.

[0024] (Effects of this embodiment) As described above, the electric vehicle 2 includes the drive unit 22 having the wheels 12r, 12l, the motor 24 that drives the wheels 12r, 12l, and the disconnect mechanism 28 provided in the torque transmission path 32 between the motor 24 and the wheels 12r, 12l, and the control device 40 that controls the disconnect mechanism 28. The disconnect mechanism 28 can selectively achieve a connected state in which the torque transmission path 32 is connected, a disconnected state in which the torque transmission path 32 is disconnected, and a standby state that is a state between the connected state and the disconnected state. The control device 40 switches the disconnect mechanism 28 from the connected state to the standby state when the electric vehicle 2 travels on an uneven road (S10 in FIG. 2), and switches the disconnect mechanism 28 from the standby state to the disconnected state when the electric vehicle 2 suddenly brakes (YES in S30) after switching the disconnect mechanism 28 to the standby state.

[0025] According to the above configuration, when the electric vehicle 2 travels on an uneven road, the disconnect mechanism 28 is switched from the connected state to the standby state. Therefore, when the electric vehicle 2 is suddenly braked thereafter, the disconnect mechanism 28 is switched to the disconnected state relatively quickly. Therefore, torsional resonance occurring in the drive unit 22 can be more reliably suppressed. [Explanation of symbols]

[0026] 2: electric vehicle, 10: vehicle body, 12l, 12r: wheels, 20: battery, 22: drive unit, 24: motor, 26: transmission mechanism, 28: disconnect mechanism, 30: differential mechanism, 32: torque transmission path, 40: control device, 42: sensors

Claims

[Claim 1] An electric vehicle, Wheels and a drive unit including a motor that drives the wheels and a disconnect mechanism provided in a torque transmission path between the motor and the wheels; a control device that controls the disconnect mechanism, the disconnection mechanism is capable of selectively realizing a connected state in which the torque transmission path is connected, a disconnected state in which the torque transmission path is disconnected, and a standby state which is a state between the connected state and the disconnected state, The control device switching the disconnect mechanism from the connected state to the standby state when the electric vehicle is traveling on an uneven road; after switching the disconnection mechanism to the standby state, when the electric vehicle suddenly brakes, the disconnection mechanism is switched from the standby state to the disconnection state; Electric vehicle.

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