Dynamic Analysis of Automotive Hypoid Gears

The dynamics of differentials in rear wheel drive vehicles are of major importance for the automotive industry. Hypoid transmissions — forming the motion transfer mechanism from the driveshaft to the wheels — often suffer from severe vibrations, which could lead to Noise, Vibration and Harshness (NVH) issues. The latter are often attributed to improper mesh between the mating gear flanks due to misalignments, variation of contact load and shifting of the effective mesh position. A new modelling approach on the torsional dynamics of hypoid gear pairs is presented in this work. This is characterised by an alternative expression of the Dynamic Transmission Error (DTE), which accounts for the variation of the effective mesh position. Numerical results indicate the enriched dynamic behaviour that can be predicted using the new formulation. A solution continuation method is employed to follow the response branches over the operating range of the differential under examination. The ensuing parametric studies convey the importance of the main system parameters on the dynamic behaviour of the differential, yielding suggestions for design guidelines.