Gear rattle modelling and analysis for automotive

OILPAN

M Y Wang*, R Manoj and W Zhao
Department of Mechanical Engineering, University of Maryland, College Park, Maryland, USA

Abstract: This paper describes a model for torsional vibration of automotive manual transmissions
and its subsequent analysis. The model is developed for the purpose of analysis and prediction of
gear rattles. EVorts have been made to include as many components of power train as possible and
to study the rattle responses of all the speeds. Elements of the model include engine, clutch,  ywheel,
laden and unladen gears, and shafts. Numerical methods available in MATLAB for solving the
ordinary diVerential equations are employed for the dynamic analysis. Results are presented to show
the eVectiveness of the modelling and analysis scheme. A software package has also been developed
to build and analyse any power train model. The package was used to analyse the Daimler-Chrysler
T350 transmission and the results are presented in the paper. It is shown that the gear rattle may
exhibit three major modes of double-sided, single-sided or irregular impacts. A rattle index has been
used to compare the rattle levels produced by diVerent gear pairs. This could be very useful for the
purpose of tuning the clutch for the best rattle noise reduction.

Keywords: gear rattle, rattle noise, automotive transmissions