An analysis of the automotive driveline dynamic behaviour focusing on the influence of the oil squeeze effect on the idle rattle phenomenon

In this paper a theoretical analysis concerning the influence of the oil damping effects on the dynamic behaviour of manual automotive transmissions, in the "idle" operating condition, is proposed. The study presents an analytical model that accounts both for the hysteretic friction in the clutch springs and for the oil squeeze effect between the impacting teeth of the meshing gears. This last dissipative term, generally neglected in the literature, has been modelled by the authors in order to consider its influence on the "gear rattle" phenomenon. The results provided by a wide numerical investigation are presented and enable a qualitative comparison between the effects due to the oil and those due to the hysteretic friction in the clutch on the rattle level.