Pitch control device for electric vehicles

Abstract

To suppress a change in a vehicle's attitude due to a pitch motion during vehicle braking, a pitch control device for an electric vehicle can prevent discontinuous negative acceleration from occurring at a moment of the vehicle stopping by appropriately controlling a braking force of the vehicle, thereby effectively controlling the pitch motion of the vehicle, and can enhance steering stability while ensuring riding comfort for passengers, even when traveling resistance significantly changes according to road surface gradient and when the vehicle weight significantly changes with increases / decreases in the number of drivers and in the quantity of goods loaded. This pitch control device for an electric vehicle, configured to conduct pitch control for suppressing the change in the attitude of the vehicle due to the pitch motion of the electric vehicle, controls the vehicle so that a braking / driving torque command value that is output to a motor for driving the vehicle when the vehicle stops will be a traveling resistance equivalent torque that is a value obtained by converting a force needed to stop the vehicle on a sloped road surface and maintain the vehicle in a stopped condition, into a torque of the driving motor.

Description

technical field [0001] The present invention relates to a vehicle control device for an electric vehicle, and more particularly, to a technique for suppressing pitching motion of a vehicle. Background technique [0002] The dynamics of the vehicle's attitude are determined by the suspension telescoping of the front and rear wheels, known as the pitching motion. [0003] It is known that the dynamics of the vehicle posture caused by the pitching motion changes according to the running state and the state of the road surface. [0004] For example, when the vehicle accelerates and decelerates, the front-rear direction of the vehicle body generates a moment around the center of gravity, called a pitch moment, in a vertically changing orientation. [0005] A pitching motion is caused by this pitching moment. [0006] In particular, when the vehicle is stopped by braking, since the braking torque is continuously applied to the vehicle until the vehicle stops, a nose-dive that ca...

AI Technical Summary

Problems solved by technology

[0007] Furthermore, since the deceleration based on this braking torque disappears suddenly as the vehicle stops, there is a problem that the energy stored in the suspension due to nodding is released at the same time, causing nodding vibrations.

[0009] Although the ride comfort and handling stability of the vehicle can be adjusted by setting the springs and shock absorbers of the suspension device, it is very difficult to simultaneously achieve ride comfort and handling stability.

[0010] This is because ride comfort and handling stability are opposite characteristics, and in an actual vehicle, the weight of the vehicle varies greatly due to changes in the load of passengers and cargo, so it is difficult to determine the optimum value under all conditions

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