NVH numerical analysis of the mounting layout of hydrostatic transmissions in continuously variable transmissions

The present work proposes a numerical approach to model the dynamic behavior of the mounting layout of hydrostatic transmissions in continuously variable transmissions for off-road vehicles. The methodology takes advantage of a finite element model constituted by a rigid body, representing the hydrostatic transmission, connected to the overall transmission frame through a combination of torsional couplings, rolling-element bearings and brackets, considered as flexible components. Bearings, in particular, are substituted with nonlinear springs, while brackets and frames are 3D meshed according to the actual geometry of the system. The model allows to estimate the frequency dependent forces applied on the frame in reference to the loads generated within the hydrostatic transmission. The method is applied on a case study, showing that the torsional joints play a relevant role on the overall NVH behavior of the system and their kinematic characteristics should be carefully defined to tune the loads transmitted on the transmission frame.