Abstract
This paper is aimed to investigate the influence of dual-mass flywheel (DMF) kinetic parameters on driveline torsional vibration in engine start-up process, which prescribes the design requirements under start-up condition for DMF matching. On the basis of driveline excitation analysis during engine start-up, the analytical model of DMF driveline torsional vibration system is built and simulated. The vehicle start-up test is conducted and compared with the simulation results. On account of the partial nonstationary characteristic of driveline during start-up, the start-up process is separated into 3 phases for discussing the influence of DMF rotary inertia ratio, hysteresis torque, and nonlinear torsional stiffness on attenuation effect. The test and simulation results show that the DMF undergoes severe oscillation when driveline passes through resonance zone, and the research model is verified to be valid. The DMF design requirements under start-up condition are obtained: the appropriate rotary inertia ratio (the 1st flywheel rotary inertia-to-the 2nd flywheel rotary inertia ratio) is 0.7∼1.1; the interval of DMF small torsion angle should be designed as being with small damping, while large damping is demanded in the interval of large torsion angle; DMF should be equipped with low torsional stiffness when working in start-up process.
Highlights
Academic Editor: Stefano Manzoni is paper is aimed to investigate the influence of dual-mass flywheel (DMF) kinetic parameters on driveline torsional vibration in engine start-up process, which prescribes the design requirements under start-up condition for DMF matching
E traditional clutch torsional damper (CTD) cannot meet the requirements for torsional vibration control presently, since many defects have been proved [1], e.g., driveline resonance at idle speed or commonly used speed. e dual-mass flywheel torsional vibration damper (DMF) separates the flywheel into two components, the primary flywheel and the secondary flywheel, which are connected by springs and damping mechanism [2]
Wang et al studied the DMF parameters matching and design method based on driving and overload conditions at different engaged gear pairs, and a DMF with 3-stage torsional stiffness was designed [12]
Summary
It is inappropriate to utilize sinusoidal signal as excitation for studying the oscillation in start-up process on account of the partial unsteady state induced by starter input torque and engine cylinder ignition. After all the cylinders are entirely ignited, the driveline torsional vibration is generally derived from the crankshaft system vibration, including the torque fluctuation caused by reciprocating mechanical movement of piston and connecting rod and the variation of cylinder gas pressure [15, 16]. For a 4-cylinder 4-stroke engine, the torque caused by the reciprocating mass, Trm, can be expressed as. E engine torque TΣ can be expressed as TΣ Trm + Tg. For a 4-cylinder 4-stroke engine, the vibration will increase distinctly when the harmonic numbers are 2, 4, 6, . Where c is harmonic number and n(rpm) is crankshaft rotational speed
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