Sealing device

Abstract

A sliding portion between a seal lip ( 7 ) and the circumference of a shaft ( 3 ) is made of a sliding face ( 10 ) so that the facial pressure at the initial action time can be lowered to suppress the proceeding of the wear of the seal lip ( 7 ) thereby to elongate the lifetime of a sealing device ( 1 ). Moreover, screw ridges ( 12 ) are formed from an atmospheric side slope ( 11 ) to a sliding face ( 10 ) so that satisfactory sealing properties can be exhibited initially and endurably for a long time.

1 - 4 . (canceled)  
   
   
       5 . A sealing device for sealing an annular clearance between two members assembled to rotate relative to each other, said sealing device comprising a seal lip for sliding on the circumference of one of said two members, 
 wherein said seal lip includes:    a sliding face extending along said circumference;    an atmospheric side slope inclined to enlarge the clearance gradually between the slope and said circumference from the atmospheric side end edge of said sliding face; and    a screw ridge formed from said atmospheric side slope to said sliding face, and    wherein said screw ridge is formed along said atmospheric side slope and to have such a shape that its end portion on the side of said sliding face is cut off along said sliding face.    
   
   
       6 . A sealing device according to  claim 5 , wherein the internal angle of a joint between two portions of said screw ridge, the one portion being arranged on said atmospheric side slope and the another portion being arranged on said sliding face, is a salient angle.  
   
   
       7 . A sealing device according to  claim 5 , wherein second screw ridge is formed only on said sliding face.