Grease composition for EV/HEV driving motor bearing and EV/HEV driving motor bearing

摘要

A grease composition for EV/HEV driving motor bearing, containing a diurea thickener of the following formula (A):;wherein R1, R2 and R3 are defined, 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))×100] being 60 to 80%, and a base oil which has a kinematic viscosity at 40° C. of 15 to 50 mm2/s and includes a trimethylolpropane ester oil in an amount of 80 mass % or more based on the total base oil mass. The grease composition can exhibit a long bearing lubrication life at high temperature and high speed, and satisfactory low-temperature flowability.

主权项

1. A grease composition for use in an EV/HEV driving motor bearing, comprising a thickener and a base oil,
wherein the thickener is a diurea compound represented by formula (A): wherein R2 is represented by the formulaand R1 and R3, 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))×100] being 60 to 80%; and
the base oil comprises a trimethylolpropane ester oil in an amount of 80 mass % or more based on the total mass of the base oil and has a kinematic viscosity at 40° C. of 15 to 50 mm2/s, wherein the trimethylolpropane ester oil is an ester of trimethylolpropane with two or more straight-chain or branched fatty acids having 8 to 12 carbon atoms, and the grease composition further comprises diphenylamine and hindered phenol-based antioxidants, the amount of the thickener is 11 to 16 mass % based on the total mass of the grease composition, and the total amount of the antioxidants is 2.0 to 3.0 mass % based on the total mass of the grease composition.