Research on Idling Rattle of Manual Transmission

Generation mechanism and characteristics of idling rattle are systematized analytically by experiments on vehicle and digital simulation of nonlinear torsional vibration system for an inline four-cylinder four-cycle compact diesel engine.

Jumping and hysteresis of the noise level are caused by both decreasing engine torque fluctuations while engine rotating velocity increases, and clutch-disc torsional characteristics of two-staged hardening spring. An improved clutch disc with a decreased noise level of 5 dB (A) was developed clarifying the optimum combination of disc characteristics, and permitting engine rotating velocity, where jumping occurs, below idling rotating velocity.