OPTIMIZATION OF ASYMMETRIC DAMPER PARAMETERS OF AN AUTOMOTIVE SUSPENSIONFOR MINIMAL CAMBER ANGLE VARIATIONS

摘要

Asymmetric dampers invariably employed in automotive suspensions are known to cause 'damper jacking'. The influence of the damper jacking on the suspension kinematic responses, particularly variations in the camber angle, are generally ignored while synthesizing a damper. This study presents influences of damper asymmetry on the camber angle variations of a double wishbone type of suspension together with the dynamic responses under measured urban road inputs. Simulation studies employing a kineto-dynamic quarter-car model comprising a bilinear damper revealed increase in the camber angle variations with an increase in the damper asymmetry, while this increment showed nonlinear relation with the suspension deflection. This study further investigates synthesis of an optimal two- stage asymmetric damper to yield a compromise between the conflicting performance measures. A composite performance index comprising the ride comfort and road holding measures with limit constraint on camber angle variation is formulated to seek optimal damper parameters. The results are presented so as to yield design guidance for synthesis of asymmetric dampers.