Slide rail device for vehicle seat

Abstract

A slide rail device which includes a lower rail, an upper rail which is freely slidably engaged with the lower rail, and balls which are installed between the lower and upper rails. The lower rail includes a lower-rail bottom wall, a pair of lower-rail side walls, a pair of lower-rail upper wails, a pair of lower-rail lower-ball contact R-portions, and a pair of lower-rail upper-ball contact R-portions. The upper rail includes an upper-rail top wall, a pair of upper-rail side walls, and a pair of upper-rail ball-bearing walls. Each upper-rail ball-bearing wall includes an upper-rail lower-ball contact portion and an upper-rail upper-ball contact portion. A radius of curvature of the lower-rail lower-ball contact R-portion of the lower rail is greater than that of the lower ball, and a radius of curvature of the lower-rail upper-ball contact R-portion of the lower rail is greater than that of the upper ball.

1 . A slide rail device which includes a lower rail having a uniform cross section, an upper rail having a uniform cross section which is freely slidably engaged with said lower rail, and balls which are installed between said lower rail and said upper rail,
 wherein said lower rail comprises:   a lower-rail bottom wall;   a pair of lower-rail side walls which extend upward from both ends of said lower-rail bottom wall, with respect to a lateral direction, respectively;   a pair of lower-rail upper walls which extend toward a center of said lower rail in the lateral direction from upper ends of said pair of lower-rail, side walls, respectively; and   a pair of lower-rail lower-ball contact R-portions via which said pair of lower-rail side walls are connected to said lower-rail bottom wall, respectively; and   a pair of lower-rail upper-ball contact R-portions via which said pair of lower-rail upper walls are connected to said pair of lower-rail side walls, respectively,   wherein said upper rail comprises:   an upper-rail top wall;   a pair of upper-rail side walls which are continuous with said upper-rail top wall and extend downward between said pair of lower-rail upper walls into said lower rail from both sides of said upper-rail top wall with respect to said lateral direction, respectively; and   a pair of upper-rail ball-bearing walls winch extend outwardly upwards from lower ends of said pair of upper-rail side walls, respectively,   wherein each of said pair of upper-rail ball-bearing walls includes an upper-rail lower-ball contact portion which is formed to face an adjacent lower-rail lower-ball contact R-portion of said pair of lower-rail lower-ball contact R-portions of said lower rail   wherein said balls include a pair of lower balls which are installed between said pair of lower-rail lower-ball contact R-portions of said lower rail and said upper-rail lower-ball contact portions of said pair of upper-rail ball-bearing walls of said upper rail, respectively, and   wherein a radius of curvature of said lower-rail lower-ball contact R-portion of said lower rail is greater than a radius of said lower ball.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The slide rail device according to claim  2 , wherein said upper-rail lower-ball contact portion of each of said pair of upper-rail ball-bearing walls of said upper rail is formed as an upper-rail lower-ball contact R-portion that is formed into a circular arc shape with a specific curvature in cross section, a radius of curvature of said upper-rail lower-ball contact R-portion being greater than said radius of said lower ball. 
     
     
         5 . The slide rail device according to  claim 1 , wherein the following conditions are satisfied:
     R 1≧1.1 r 1, and
   wherein r 1  designates said radius of said lower ball, and   R 1  designates said radius of curvature of said lower-rail lower-ball contact R-portion   
     
     
         6 . (canceled) 
     
     
         7 . The slide rail device according to  claim 1 , wherein said lower rail further comprises a pair of lower-rail inner side walls which are positioned between said pair of lower-rail side walls and extend downward from inner ends of said pair of lower-rail upper walls, respectively. 
     
     
         8 . (canceled)