Classification of transient vibration of passenger cars powertrain

Abstract

This work is a study on transient vibrational behaviour of a vehicle driveline system during tip-in/released/tip-out throttle. The considered vehicle is a passenger sedan, front-wheel drive, front-engine equipped with a four-stroke four-cylinder SI engine and a 5-speed manual transmission. The engine's model follows the mean value model including the effects both dynamics and combustion parameters including manifold/engine volume, air to fuel ratio, spark advance/retard and RPM on its transient indicator and brake torque behaviour. A primary fourteen-degrees-of-freedom lumped parameter torsional driveline model including, a multi-staged clutch with nonlinear clutch springs model and the gear backlash effect on idle as well as engaged gears is considered. This model is reduced to a six-degrees-of-freedom model. A rigid 2D model and magic formula are used for modelling of vehicle-tyre-road dynamics interaction. Using the overall model, the role of the driving style, the engine dynamics and longitudinal vehicle-road dynamic interaction in creating and intensifying the shuffle, clonk, and shunt, are studied and summarized, as the particular focus of this study. Although the results verify the other related researches on the importance of nonlinear parameters such as nonlinear stiffness, backlash and gear teeth impact, on the intensity of vibro-impact responses, they prove that engine's dynamics/combustion parameters such as engine volume, intake manifold volume and spark advance timing as well as driving style and also tyre-road parameters such as coefficient of friction and road grade have significant role in intensifying the vibro-impact responses. For example, (a) the smaller the engine, the larger amplitude the shuffle; (b) the sport driving style intensifies the both the clonk and the shuffle and (c) the more slippery road in time of the tip-out, the more strengthen the shuffle. The results of the overall driver/engine/driveline/tyre/road model provide more knowledge towards better understanding of vibro-impact response of the driveline.