Valve timing adjustment device

Abstract

A valve timing adjustment device includes: a center bolt being bottomed cylindrical; a spool disposed in a hollow portion of the center bolt so as to be linearly movable; an oil supply path including a region that is formed inside a cylindrical wall of the center bolt and along the longitudinal direction of the center bolt; a first annular groove formed on the inner periphery of the center bolt and communicating with the oil supply path; and a second annular groove formed on the outer periphery of the spool, disposed to face the first annular groove, and communicating with the oil supply path via the first annular groove. The oil supply path is capable of selectively, communicating with either a first work port or a second work port via the first annular groove and the second annular groove depending on the position of the spool that is linearly moving.

1 . A valve timing adjustment device comprising;
 a center bolt being bottomed cylindrical;   a spool disposed in a hollow portion of the center bolt so as to be linearly movable;   an oil supply path including a region that is formed inside a cylindrical wall of the center bolt and along a longitudinal direction of the center bolt;   a first annular groove formed on an inner periphery of the center bolt and communicating with the oil supply path; and   a second annular groove formed on an outer periphery of the spool, disposed to face the first annular groove, and communicating with the oil supply path via the first annular groove, wherein   the oil supply path is capable of selectively communicating with either a first work port or a second work port via the first annular groove and the second annular groove depending on a position of the spool that is linearly moving.   
     
     
         2 . The valve timing adjustment device according to  claim 1 , further comprising a third annular groove formed on an outer periphery of the center bolt and at a position corresponding to the first work port. 
     
     
         3 . The valve timing adjustment device according to  claim 1 ,
 further comprising a fourth annular groove formed on an outer periphery of the center bolt and at a position corresponding to the second work port.   
     
     
         4 . The valve timing adjustment device according to  claim 2 , further comprising a fourth annular groove formed on an outer periphery of the center bolt and at a position corresponding to the second work port.