Analytical and Experimental Study On Gear Rattle In Supercharger

Supercharger timing gears have been a source of rattle noise due to torsional vibration from the engine and sometimes have required torsional isolators to reduce the rattle noise significantly. Supercharger gear rattle is studied analytically and experimentally in this paper in order to understand to what extent basic design parameters could impact gear rattle noise to eliminate the need for isolators. A 3 DOF (degree of freedom) discrete model is used to represent a geared rotor system in the supercharger. A mathematical dynamic model is established in Matlab handling the non-linearity due to gear backlash. The fluctuation of input torque is used as source of excitation. A real time simulation technique is used for the analysis. Good correlation has been obtained between the experimental and analytical results. An index for comparing analytical results to gear noise and vibration level has been proposed. Parametric studies were performed to investigate the effects of main design parameters on gear rattle vibration and showed potential solutions.