GREASE COMPOSITION FOR EV/HEV DRIVING MOTOR BEARING AND EV/HEV DRIVING MOTOR BEARING

摘要

The invention provides a grease composition for EV/HEV driving motor bearing, containing a diurea thickener of the following formula (A): wherein R 2 is a bivalent aromatic hydrocarbon group having 6 to 15 carbon atoms; and R 1 and R 3 , which may be the same or different represent a straight-chain or branched alkyl group having 16 to 20 carbon atoms or cyclohexyl group, with the ratio of the number of moles of the straight-chain or branched alkyl group having 16 to 20 carbon atoms to the total number of moles of the cyclohexyl group and the straight-chain or branched alkyl group having 16 to 20 carbon atoms, expressed as [((the number of alkyl group) / (the number of cyclohexyl group + the number of alkyl group)) x 100] being 60 to 80%, and a base oil which has a kinematic viscosity at 40°C of 15 to 50 mm 2 /s and includes a trimethylolpropane ester oil in an amount of 80 mass% or more based on the total mass of the base oil. The grease composition of the invention can exhibit a long bearing lubrication life under the conditions of high temperature and high speed, and satisfactory low-temperature flowability.