Device for controlling torque distribution to left and right wheels on vehicle

Abstract

In the disclosed device, a computation unit (43) obtains, from the rate of change (dtf) of a target yaw rate, a left / right rear-wheel torque-difference transient control calculation value (dd[delta]TcLR), which is a fundamental target value for a turn response transiently requested by the driver in accordance with a steering speed on the basis of a current wheel speed (Vw) (vehicle speed). From the rate of change (dtf) of the target yaw rate, another computation unit (45) obtains a left / right torque-difference transient control gain (a) that is less than 1 in a region in when the target yaw rate is changing rapidly. Then, dd[delta]TcLR is multiplied by a to obtain a left / right rear-wheel torque-difference transient control term (d[delta]TcLR), which is used in controlling torque distribution to left and right wheels. As a result, during high-speed steering, when the yaw-rate gain increases, the left / right torque-difference transient control term is corrected downwards and said transient control term inhibits further increases in yaw rate, preventing vehicle behavior from becoming unstable.

Description

technical field [0001] The present invention relates to an improvement proposal of a drive force distribution control device for left and right wheels useful for vehicles, particularly four-wheel drive vehicles. Background technique [0002] As a driving force distribution control device for the left and right wheels of a vehicle, for example, a technology described in Patent Document 1 has been proposed so far. [0003] In this proposed technology, when transiently controlling the distribution of driving force to the left and right wheels so as to achieve a target behavior change (usually a change in yaw rate) corresponding to a change in the vehicle's operating state, a high-speed By making the driving force distribution between the left and right wheels so that the difference between the left and right wheels increases during steering, the transient response during high-speed steering can be improved. [0004] Patent Document 1: Specification of Patent No. 3116685 [00...

AI Technical Summary

Problems solved by technology

[0005] However, it is known that the gain of the vehicle behavior (yaw rate) with respect to the steering speed is different for each vehicle speed, but it is possible to maintain approximately the same gain in a region where the steering speed is low for any vehicle speed. When steering at high speed, the steering frequency coincides with the yaw resonance frequency of the vehicle, and a yaw moment larger than the yaw moment corresponding to the steering is generated, so the gain tends to be higher than that at low speed steering

[0006] However, the above-mentioned transitional control technology for the distribution of driving force between the left and right wheels distributes the driving force between the left and right wheels in such a way that the driving force difference between the left and right wheels becomes larger when the steering degree is faster. rate) in high-speed steering where the gain relative to the steering speed is increased, the transient control of the left and right wheel drive force distribution is too large, and the vehicle behavior is unstable due to an unnecessary excessive yaw rate, resulting in a problem of deteriorating drivability

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