Heat-resistant, high-speed, high-load rolling bearing and grease composition

Abstract

A heat-resistant, high-speed, high-load rolling bearing for automotive accessories and electric part is provided which develops no abnormal flaking and is sufficiently long in life and superior in durability. It is a heat-resistant, high-speed, high-load rolling bearing in which is sealed a grease composition which comprises a base oil which is a mixture alkyldiphenyl ether oil and aromatic ester oil at the ratio (in weight) of 50:50 to 80:20, a diurea compound expressed by the following formula as a thickening agent, and 0.1 to 5 wt % of a passivating agent. (wherein R 2 is an aromatic hydrocarbon group having a carbon number of 6-15, R 1 and R 3 are an aromatic hydrocarbon groups having a carbon number of 6-12 or a cycloaliphatic hydrocarbon group having a carbon number of 6-20. R 1 and R 3 may be identical to or different from each other.)

What is claimed is:  
     
         1 . A heat-resistant, high-speed, high-load rolling bearing in which is sealed a grease composition which comprises a base oil which is a mixture alkyldiphenyl ether oil and aromatic ester oil at the ratio (in weight) of 50:50 to 80:20, a diurea compound expressed by the following formula as a thickening agent, and 0.1 to 5 wt % of a passivating agent.  
       
         
           
           
               
               
           
         
         (wherein R 2  is an aromatic hydrocarbon group having a carbon number of 6-15, R 1  and R 3  are an aromatic hydrocarbon groups having a carbon number of 6-12 or a cycloaliphatic hydrocarbon group having a carbon number of 6-20. R 1  and R 3  may be identical to or different from each other.)  
       
     
     
         2 . The heat-resistant, high-speed, high-load rolling bearing as claimed in  claim 1  wherein the rate of the aromatic hydrocarbon group relative to the total amount of R 1  and R 3  is 50-100 mol %.  
     
     
         3 . The heat-resistant, high-speed, high-load rolling bearing as claimed in  claim 1  or  2  wherein said aromatic ester oil has a dynamic viscosity at 40° C. of 20 to 150 mm 2 /s.  
     
     
         4 . A grease composition for rolling bearings for use in automotive accessories or electric parts, the grease composition comprising a base oil which is a mixture alkyldiphenyl ether oil and aromatic ester oil at the ratio (in weight) of 50:50 to 80:20, a diurea compound expressed by the following formula as a thickening agent, and 0.1 to 5 wt % of a passivating agent.  
       
         
           
           
               
               
           
         
         (wherein R 2  is an aromatic hydrocarbon group having a carbon number of 6-15, R 1  and R 3  are an aromatic hydrocarbon groups having a carbon number of 6-12 or a cycloaliphatic hydrocarbon group having a carbon number of 6-20. R 1  and R 3  may be identical to or different from each other.)  
       
     
     
         5 . The grease composition as claimed in  claim 4  wherein the rate of the aromatic hydrocarbon group relative to the total amount of R 1  and R 3  is 50-100 mol %.  
     
     
         6 . The grease composition for a rolling bearing as claimed in  claim 4  or  5  wherein said accessory or electric part is an alternator, electromagnetic clutch, tension pulley or one-way clutch.  
     
     
         7 . The grease composition as claimed in  claim 4  or  5  wherein said aromatic ester oil has a dynamic viscosity at 40° C. of 20 to 150 mm 2 /s.