PREDICTION OF SPUR GEAR MECHANICAL POWER LOSSES USING AN EHL MODEL WITH TIME-VARYING CONTACT PARAMETERS

A physics-based model is proposed to predict load dependent (mechanical) power loss of spur gear pairs by using a specialized gear elastohydrodynamic lubrication (EHL) model. The EHL model includes time variations of all key contact parameters such as surface velocities, radii of curvature and normal load in their continuous forms such that a continuous analysis of a tooth contact from its root to tip can be performed. The EHL model has the capability to simulate any gear contacts represented by condition ranging from full EHL to mixed or boundary EHL conditions. Predicted transient pressure and film thickness distributions are used to determine the instantaneous as well as the overall mechanical power loss of the gear mesh. Correction factors are introduced to account for thermal effects. At the end, capabilities and accuracy of the proposed model are demonstrated by comparing its predictions to experimental data.