Gear impacts and idle gear noise: Experimental study and non-linear dynamic model

This paper develops an experimental and numerical study of dynamic phenomena involving gear impacts with one loose gear (non-engaged gear pair) inside an automotive gearbox.A dedicated test bench was designed for this study. Signal processing tools, based on the Order Tracking Method, were specially developed in order to clarify the underlying phenomena. A particular attention was paid to the relationship between the drive shaft excitation and the energy and nature of impacts.A topological model of contact is being proposed, based on a geometric description of solids in contact. The contact between gear meshes is defined using a Single Degree of Freedom, non-linear, elastic and dissipative model. The chosen parameters of the model are not updated from measurements, but from the knowledge of the gear topology and tolerance class.Simulations, compared with experimental results, confirm the accuracy of the model proposed.Both model and experiments show, for particular excitation conditions, the emergence of repeated impacts on one side of the gear mesh.