The Nonlinear Characteristics Impact of Multi-Staged Stiffness Clutch Damper on the Vehicle Creeping 2016-01-0431

The nonlinear characteristics impact of multi-staged stiffness clutch damper on the vehicle creeping is investigated by using the lumped-parameter modeling method as a certain mass-production passenger sedan is taken as the research subject. Firstly, a quasi-transient engine model of an inline four-cylinder and four-stroke engine, based on measured data of cylinder gas pressure versus crankshaft angle, is derived. Effective output torque is acquired and as the input excitation to the driveline system. Secondly, a 12-DOF (Degree of Freedom) nonlinear and branched powertrain system and vehicle longitudinal dynamics model is established. The differential mechanism characteristics and dynamic tire property based on the LuGre tire model are considered. Then, for a traditional two-staged stiffness clutch damper in consideration of hysteresis characteristics, vehicle powertrain system responses in both the time and frequency domain are obtained. It’s concluded that the clutch damper operates jumping between the first and the second stage stiffness region and the driveline undergoes severe torsional vibration. Finally, a novel three-staged stiffness clutch damper is constructed mechanically and analyzed for the vehicle creeping. Simulation results in both the time and frequency domain indicate that powertrain system torsional fluctuations are reduced dramatically and the self-excited vibration due to jumping phenomenon between two stage stiffness regions is eliminated thoroughly. Overall, this paper is expected to show that nonlinear parameters optimization of multi-staged stiffness clutch damper, based on the effective and lowcost modification, could be a practical measure to reduce powertrain system torsional fluctuations, rather than adopting costly dual mass flywheel.