Effect of Viscosity Characteristics of Lubricants for Electric Vehicles on Thermal Conductivity and Gear Protection

The purpose of this study is to investigate how the kinematic viscosity of lubricating oil used in hybrid electric vehicle (HEV) and electric vehicles (EV) transaxles affects thermal conductivity and gear seizure resistance. This study investigated the relationship between viscosity, thermal conductivity and gear seizure resistance in detail and found that thermal conductivity tends to decrease with decreasing viscosity. It was also found that the thermal conductivity decreases significantly after a certain viscosity. The relationship between viscosity and gear seizure resistance was also investigated and it was found that too low a viscosity causes a significant deterioration in gear seizure resistance.