Fluorescent grease and bearings having the same therein

Abstract

The invention provides a fluorescent grease which enables monitoring of behaviors of the grease for elucidation of the mechanism of grease lubrication, and a rolling element bearing or a condition monitoring rolling element bearing, both charged with the fluorescent grease. The fluorescent grease contains, as its essential components, a base oil, a thickener agent, and a fluorescent substance.

What is claimed:  
     
         1 . A fluorescent grease comprising, as essential components, a base oil consisting of a synthetic carbonate ester, a thickener agent consisting of a lithium soap and a fluorescent substance consisting of at least one member selected from the group consisting of pyrene, perylene, 1,6-diphenyl-1,3,5-hexatriene, 1,8-diphenyl-1,3,5,7-octatetraene and coumarine 6.  
     
     
         2 . The fluorescent grease of  claim 1 , wherein the fluorescent substance is at least one member selected from the group consisting of pyrene, perylene, 1,6-diphenyl-1,3,5-hexatriene and 1,8-diphenyl-1,3,5,7-octatetraene.  
     
     
         3 . A rolling element bearing charged with the fluorescent grease of  claim 1 .  
     
     
         4 . A condition monitoring rolling element bearing charged with the fluorescent grease of  claim 1 .  
     
     
         5 . A method of testing grease characteristics using the fluorescent grease of  claim 1 , comprising the steps of: 
 adhering the fluorescent grease to a ball;    rotating the ball while pressing the ball onto a glass substrate;    irradiating the ball with light through the glass substrate; and    observing behavior of the fluorescent grease with a CCD camera while the ball is being rotated.    
     
     
         6 . The method of  claim 5 , wherein the fluorescent grease is made of at least two fluorescent substances, the ball is irradiated with light of multiple wavelengths and plural images of the fluorescent substances appearing on the CCD are compared with one another.  
     
     
         7 . The method of  claim 6 , wherein at least one of the fluorescent substances has an affinity for the base oil and another fluorescent substance has an affinity for the thickening agent.  
     
     
         8 . A method of testing bearings characteristics comprising the steps of: 
 charging a bearing with the fluorescent grease of  claim 1;     rotating the bearing at a specified temperature for a specified time and at a specified speed;    receiving fluorescent grease dispersed from the bearing by a test piece;    irradiating the test piece with light; and    examining a grease spot on the test piece.    
     
     
         9 . The method of  claim 8 , wherein the bearing is a mechanically sealed bearing.