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

Patent metadata

Field	Value
Publication number	US-9567545-B2
Application number	US-201214131798-A
Country	US
Kind code	B2
Filing date	Jul 27, 2012
Priority date	Jul 28, 2011
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A grease composition for EV/HEV driving motor bearing, containing a diurea thickener of the following formula (A):

wherein R 1 , R 2 and R 3 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 mm 2 /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.

First claim

The invention claimed is:

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 R 2 is represented by the formula

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))×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 mm 2 /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.

2. The grease composition of claim 1 , wherein the thickener is a compound of formula (A) wherein one of R 1 or R 3 is a straight-chain or branched alkyl group having 18 carbon atoms and the other is cyclohexyl group.

3. The grease composition of claim 1 , further comprising overbased metal sulfonate.

4. The grease composition of claim 1 , having a worked penetration of 200 to 300.

5. A rolling bearing operated at a dmn value of 1,000,000 or more, where the grease composition of claim 1 is enclosed.

6. The grease composition of claim 1 , wherein the amount of the base oil is at least 81 mass % based on the total mass of the grease composition.

Assignees

• Mizuki Hironori
• Maejima Takeshi
• Iso Kenichi
• Nakagawa Kazunori
• Imai Yutaka
• Aida Ryo
• Nsk Ltd
• Kyodo Yushi

Inventors

• Mizuki Hironori
• Maejima Takeshi
• Iso Kenichi
• Nakagawa Kazunori
• Imai Yutaka
• Aida Ryo

Classifications

• C10M2207/026

  with tertiary alkyl groups · CPC title

• C10N2030/02

  Pour-point; Viscosity index · CPC title

• C10M133/12

  having amino groups bound to a carbon atom of a six-membered aromatic ring · CPC title

• C10M169/02 Primary

  Mixtures of base-materials and thickeners · CPC title

• C10N2040/02

  Bearings · CPC title