JPH11243608A - Motor-driven driving device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a shock at the time of starting to drive in a motor-driven diving device which drives an axle shaft with an electric motor via a clutch. SOLUTION: An equation of predicting the later change of the speed of revolution VR of an axle shaft is calculated based on the speed of the revolution VF and the angular acceleration dVR of an axle shaft at the time of outputting a drive command (S1). Time t required for the speed of the revolution of an electric motor Vm to become equal to the VR is calculated from this predictive equation and the speed rising characteristics of the motor (S2). The motor is made to slip during the period of the time t (S3, S4) and a clutch is engaged with the motor temporarily switched off after the time t elapsed (S5, S6). Then, the motor is restarted to increase an output torque gradually (S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric drive device for a vehicle in which an axle is driven by an electric motor via a clutch.

[0002]

2. Description of the Related Art Conventionally, one of front and rear wheels of a vehicle is an engine drive wheel driven by an engine, and the other is an electric drive wheel driven by an electric drive device, and the engine drive wheel slips when starting on a slippery road surface. There is known a hybrid four-wheel drive vehicle that drives an electrically driven wheel to assist starting when the vehicle is driven.

Here, the electric drive device is configured to transmit the output torque of the electric motor to the axle of the electric drive wheel via a clutch, and the engine drive wheel slips to drive the drive command of the electric drive wheel. Is issued, the clutch is turned on and the electric motor is energized to drive the electric drive wheels.

[0004]

In the above-mentioned prior art, a shock due to a sudden rise of the motor torque occurs at the beginning of driving of the electrically driven wheels, or a backlash or axle rotation of the power transmission system of the electrically driven device. In some cases, a shock corresponding to the motor inertia due to a difference between the motor speed and the motor rotation speed may occur, and there is a problem in terms of merchantability.

[0005] In view of the above, it is an object of the present invention to provide an electric drive device capable of preventing the occurrence of a shock at the beginning of driving.

[0006]

Means for Solving the Problems In order to solve the above problems,
According to a first feature of the present invention, in an electric vehicle drive device for driving an axle through a clutch by an electric motor, the output torque of the electric motor is gradually raised after the clutch is turned on at the beginning of driving of the axle. According to the second feature of the present invention, the clutch is driven before the axle is driven so that the electric motor idles so that the rotation speed of the electric motor becomes equal to the rotation speed of the axle. Is turned on.

[0007] If there is a backlash in the transmission system, the electric motor rotates at no load by the amount of backlash caused by the backlash at the beginning of driving, and a shock due to increased motor inertia due to rapid acceleration of the electric motor during that time occurs. According to the first feature, since the output torque of the electric motor is gradually increased, the electric motor does not suddenly accelerate even if there is a backlash, and the occurrence of a shock due to the backlash is prevented. Needless to say, the occurrence of a shock due to a sudden rise of the motor torque is also prevented.

When the vehicle is started while the vehicle is not stationary, the axle rotation speed is reduced by the inertia of the electric motor which has been stationary when the clutch is on, causing a shock. According to the characteristics of
The occurrence of deceleration shock due to motor inertia when the clutch is on is prevented by the idling of the electric motor before the clutch is on.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes left and right front wheels, 2 denotes left and right rear wheels, and engine driving in which left and right front wheels 1, 1 are driven by an engine 3 via a transmission 4. A hybrid four-wheel drive vehicle is configured in which the wheels and the left and right rear wheels 2 and 2 are electrically driven wheels driven by an electric drive device 5.

The electric drive device 5 comprises a differential gear 6 connecting the axles 2a, 2a of the left and right rear wheels 2, 2, and an electric motor 7
And a dog clutch 8 interposed in a power transmission path between the electric motor 7 and the differential gear 6, and the output torque of the electric motor 7 is supplied to the wheel 2 via the dog clutch 8 and the differential gear 6.
a, 2a. The dog clutch 8 has a fixed dog 8 a fixed to the output shaft of the electric motor 7.
And a movable dog 8b which can be freely disengaged from the fixed dog 8a, and a solenoid 8c which makes the movable dog 8b engage and disengage with the fixed dog 8b.

The electric motor 7 and the solenoid 8c comprise a front wheel speed sensor 9 for detecting the rotation speed VF of the front wheel 1, and a rear wheel 2
Is controlled by a controller 11 that inputs a signal from a rear wheel speed sensor 10 that detects the rotational speed VR of the vehicle. The controller 11 determines that the front wheel 1 slips and the front wheel speed VF
The speed difference between the rear wheel speed VR and the rear wheel speed VR is a predetermined value △ shown in FIG.
When it becomes equal to or higher than VS, a drive command for the rear wheel 2 is issued to perform drive control as shown in FIG. In this drive control, first, the rotation speed V of the rear wheel 2 at the time of output of the drive command
An equation for predicting a subsequent change in the rear wheel speed VR is calculated from R and the angular acceleration dVR of the rear wheel 2 (S1). next,
Based on the speed rise characteristic at the time of starting the electric motor 7, a time t required for the rotation speed Vm of the electric motor 7 to become equal to the speed corresponding to the rear wheel speed VR obtained by the above-described prediction equation is calculated (S2). Then, the electric motor 7 idles for this time t (S3, S4). When a time t has elapsed from the output of the drive command, the energization of the electric motor 7 is temporarily stopped (S5), and the energization of the solenoid 8c causes the movable dog 8b to engage with the fixed dog 8a to engage the dog clutch 8. Turns on (S6). Thereafter, the electric motor 7 is restarted to gradually increase its output torque (S7).

According to this, when the dog clutch 8 is turned on, the rotation speed of the electric motor 7 is increased to a speed corresponding to the rear wheel speed VR, and when the dog clutch 8 is turned on, the rear wheel 2 is driven by the inertia of the electric motor 7. Since no deceleration force is received, the occurrence of a deceleration shock is prevented. still,
If the rear wheel 2 is stationary at the time of output of the drive command, t = 0, and the dog clutch 8
Is turned on.

When the electric motor 7 is restarted after the dog clutch 8 is turned on, the electric motor 7 rotates with no load due to backlash due to backlash of the power transmission system between the electric motor 7 and the wheel 2a. When the vehicle is suddenly accelerated, the rear wheel 2 receives an acceleration force due to the motor inertia increased by the rapid acceleration at the moment when the backlash is removed and the torque transmission to the rear wheel 2 is started, and an acceleration shock occurs. However, the electric motor 7
When the motor is restarted, since the output torque of the electric motor 7 is gradually increased as described above, the electric motor 7 is not suddenly accelerated by the no-load rotation corresponding to the backlash due to the backlash, and an acceleration shock is generated. Is prevented, and the occurrence of a shock due to sudden acceleration thereafter is also prevented.

In the above embodiment, the rear wheel speed V
Although the idling time t was calculated by predicting the change in R, the rotational speed of the electric motor 7 was detected, and the idling of the electric motor 7 increased the rotational speed to a speed corresponding to the rear wheel speed VR at that time. It is also possible to turn on the dog clutch 8 when this is done. However, in the above embodiment, the electric motor 7
This is advantageous in terms of cost because a speed sensor is not required.

The embodiment in which the present invention is applied to a hybrid four-wheel drive vehicle in which the front wheels 1 are engine driven wheels and the rear wheels 2 are electrically driven wheels has been described. The present invention can be similarly applied to a hybrid type four-wheel drive vehicle in which is used as an electric drive wheel.

[0016]

As is apparent from the above description, according to the present invention, it is possible to prevent the occurrence of a shock at the beginning of driving and to improve the marketability.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a vehicle equipped with the device of the present invention.

FIG. 2 (A) is a flowchart showing the control contents of the electric drive device, and (B) is a time chart showing the operation timing of the motor and the clutch.

[Explanation of symbols]

2a axle 4 electric drive 7
Electric motor 8 Dog clutch 11 Controller

Claims (2)

[Claims] 1. An electric vehicle drive system in which an axle is driven by an electric motor via a clutch, wherein at the beginning of driving of the axle, an output torque of the electric motor is gradually increased after the clutch is turned on. Electric drive for vehicles. 2. An electric vehicle drive system in which an axle is driven by an electric motor via a clutch. Before driving the axle, the electric motor is driven so that the rotation speed of the electric motor becomes equal to the rotation speed of the axle. An electric drive device for a vehicle, wherein a clutch is turned on after idling a motor.