Linear motion device

Abstract

A linear motion device has: a linear motion body externally fitted onto a shaft and making a relative linear motion along the shaft; a plurality of balls retained in a rolling element groove formed in an inner surface of the linear motion body, and rolling between the rolling element groove and the shaft; separators interposed among the balls; and a circulating path formed in the linear motion body and for circulating the balls from one end side of the rolling element groove to the other end side thereof; wherein the linear motion device is charged with grease containing base oil which is 220-395 in worked penetration defined by JIS K2220 and 50-500 mm 2 /s in kinematic viscosity at 40° C.

1 . A linear motion device comprising: 
 a linear motion body externally fitted onto a shaft and making a relative linear motion along the shaft;    a plurality of balls retained in a rolling element groove formed in an inner surface of the linear motion body, and rolling between the rolling element groove and the shaft;    separators interposed among the balls; and    a circulating path formed in the linear motion body and for circulating the balls from one end side of the rolling element groove to the other end side thereof;    wherein the linear motion device is charged with grease containing base oil which is 220-395 in worked penetration defined by JIS K2220 and 50-500 mm 2 /s in kinematic viscosity at 40° C.    
   
   
       2 . The linear motion device according to  claim 1 , wherein surfaces of each of the separators in contact with the balls are concave surfaces each formed with a curvature radius larger than a radius of each of the balls.  
   
   
       3 . The linear motion device according to  claim 1 , wherein surfaces of each of the separators in contact with the balls are concave surfaces each formed with a curvature radius larger than a radius of each of the balls, and a through hole formed to penetrate each of the separators from one of the concave surfaces to the other of the concave surfaces is formed in a central portion of the separator.  
   
   
       4 . The linear motion device according to  claim 1 , wherein surfaces of each of the separators in contact with the balls are concave surfaces each formed with a curvature radius larger than a radius of each of the balls, and a through hole formed to penetrate each of the separators from one of the concave surfaces to the other of the concave surfaces is formed in a central portion of the separator, while lips extending outward are formed integrally with the separator at a plurality of locations in a circumferential edge of each of the concave surfaces.  
   
   
       5 . The linear motion device according to  claim 1 , wherein surfaces of each of the separators in contact with the balls are concave surfaces each formed with a curvature radius larger than a radius of each of the balls, and a through hole formed to penetrate each of the separators from one of the concave surfaces to the other of the concave surfaces is formed in a central portion of the separator, while lips made of separate members are provided additionally to the separator at a plurality of locations in a circumferential edge of each of the concave surfaces so as to extend outward.  
   
   
       6 - 13 . (canceled)