ON EXPERIMENTAL-ANALYTICAL EVALUATION OF PASSENGER CAR RIDE QUALITY SUBJECT TO EN- GINE AND ROAD DISTURBANCES

A straightforward approach is presented to investigate the ride dynamic system for a typical rear-drive passenger car. The procedure is based on introducing two main ride excitation sources, i.e., engine/driveline and road inputs, which red uce passengers’ comfort. The measured engine fluctuating torques are applied on the coupled m odel of the driveline and the suspension, to obtain the vehicle body longitudinal vibrat ion. Further, the body vertical response to an average road roughness, is found by employing the quarter-car model. Through the frequency analysis done in this paper, it is shown that we can fastly determine the transfer functions of the systems and also their forced responses at t he desired positions, without guessing any initial conditions for the states. The results illus trate that the high frequency inputs, from the engine, are appropriately damped by the current suspension. Hence, the associated vehicle body longitudinal acceleration meets the Internat ional Standard Organization (ISO) criteria. This is not the case for the low frequency disturba nces, from the road surface irregularities, where the vehicle body vertical acceleration is a bove the ISO criteria.