Patent ID: 9592714
Date: 2017-03-14
CPC Classifications: B60G

Claim:
1. A vehicle control device comprising: a spring mechanism configured to connect a sprung member and an unsprung member of a vehicle, and generate a spring force according to a relative displacement between the sprung member and the unsprung member, the spring mechanism having a spring coefficient that is a variable spring coefficient for variably controlling the spring force; a damping mechanism configured to connect the sprung member and the unsprung member, and generate a damping force for damping a relative motion between the sprung member and the unsprung member, the damping mechanism having a damping coefficient that is a variable damping coefficient for variably controlling the damping force; and a controller, wherein the spring mechanism and the damping mechanism are disposed in parallel, the spring mechanism and the damping mechanism are controlled based on a first physical quantity relating to a sprung vibration of the vehicle and a second physical quantity relating to an unsprung vibration of the vehicle, the controller performs a control logic for controlling the spring mechanism and the damping mechanism such that when low frequency vibration corresponding to a resonance frequency of the sprung member is caused on the vehicle, the controller prioritizes a suppression of vibration of the sprung member, and when high frequency vibration corresponding to a resonance frequency of the unsprung member is caused on the vehicle, the controller prioritizes a suppression of vibration of the unsprung member, the control logic includes a first frequency weight function used to calculate a target value of the spring coefficient for controlling the spring force, and a second frequency weight function used to calculate a target value of the damping coefficient for controlling the damping force, a weight gain of the first frequency weight function is maximized at the resonance frequency of the sprung member, the weight gain of the first frequency weight function is reduced as the frequency of the sprung vibration decreases in a first region in which the frequency of the sprung vibration is lower than the resonance frequency of the sprung member and is higher than a predetermined value which is lower than the resonance frequency of the sprung member, and the weight gain of the first frequency weight function is constant in a second region in which the frequency of the sprung vibration is equal to or less than the predetermined value, a weight gain of the second frequency weight function is maximized at the resonance frequency of the unsprung member, the controller calculates, at the time a road surface displacement that generates the low frequency vibration and the high frequency vibration at the same time is input to the vehicle, the target value of the spring coefficient and the target value of the damping coefficient using the first frequency weight function and the second frequency weight function, respectively, and controls both of the spring mechanism and the damping mechanism at the same time to generate a spring force according to the calculated target of the spring coefficient and a damping force according to the calculated target value of the damping coefficient, and an increase in the weight gain of the first frequency weight function increases the spring coefficient of the spring mechanism, and an increase in the weight gain of the second frequency weight function increases the damping coefficient of the damping mechanism.