Non Linear Multibody Modelling for the Vibrational Prevision of the Shift Lever of Automotive Gearboxes

Abstract

The main task of this paper is to identify and formalize “design methodologies” useful to highlight/solve any possible problem due to the vibrations of a new gear box command system in each design stage of this component. In particular, we focused on the so-called phenomenon of “shift lever vibration” (SLV - vibration of the shift leverage in the car cabin). This phenomenon can occurs if a natural frequency of the control system is excited by a movement of the so called shift collars in the gear box. Therefore an unwanted low level of comfort and high level of noise and vibration can be experienced by the car driver. In this paper we will explain in detail the SLV phenomenon by measuring a real shift command during acceleration/deceleration manoeuvres. Then we will present two different types of multibody models developed to predict this phenomenon: the first simple-linear one is useful to “predict” the first natural frequency of the shift lever vibration. The first one can be used in the early design stage of the main components of the gearbox control. It is useful to the designer to perform a sensitivity analysis of the most important parameters to be taken into account to prevent the SLV in the cabin of the car. The second complete nonlinear multibody model is useful, not only to take into account all the non-linear aspects of the phenomenon (different behaviours in acceleration and deceleration manoeuvres), but also to predict the level of acceleration in the shift lever. The results obtainable with the multibody approach will be then compared with the results from experimental data of a real shift command.