Lash adjuster

Abstract

A lash adjuster includes a nut member inserted in a receiving hole formed in the top surface of a cylinder head, an adjusting screw having an external thread on its outer periphery which is in threaded engagement with an internal thread on the inner periphery of the nut member, and a return spring biasing the adjusting screw. The adjusting screw has an end protruding from the nut member and pivotally supporting an arm of a valve gear. The adjusting screw is a solid member. A spring seat is disposed between the adjusting screw and the return spring and kept in point contact with the end of the adjusting screw inserted in the nut member. The spring seat is axially slidably fitted in the inner periphery of the nut member, thereby keeping the adjusting screw and the spring seat coaxial with each other.

1 . A lash adjuster comprising a nut member inserted in a receiving hole formed in a top surface of a cylinder head and having an internal thread on its inner periphery, an adjusting screw having an external thread on its outer periphery which is in threaded engagement with the internal thread of the nut member and a return spring biasing the adjusting screw in a direction to protrude upwardly from the nut member, said adjusting screw having an end protruding from the nut member and pivotally supporting an arm of a valve gear, wherein said adjusting screw is a solid member, that the lash adjuster further comprises a spring seat disposed between the adjusting screw and the return spring and kept in point contact with an end of the adjusting screw inserted in the nut member, and the spring seat is axially slidably fitted in the inner periphery of the nut member, thereby keeping the adjusting screw and the spring seat coaxial with each other. 
     
     
         2 . A lash adjuster comprising a lifter body vertically slidably inserted in a guide hole formed in a cylinder head, a nut member vertically movable together with the lifter body and having an internal thread on its inner periphery, an adjusting screw having an external thread on its outer periphery which is in threaded engagement with the internal thread of the nut member, and a return spring biasing the adjusting screw in a direction to protrude downwardly from the nut member, said adjusting screw having an end protruding from the nut member and pressing a valve stem of a valve gear, wherein said adjusting screw is a solid member, the lash adjuster further comprises a spring seat disposed between the adjusting screw and the return spring and kept in point contact with an end of the adjusting screw inserted in the nut member, and that the spring seat is axially slidably fitted in the inner periphery of the nut member, thereby keeping the adjusting screw and the spring seat coaxial with each other. 
     
     
         3 . A lash adjuster comprising a nut member inserted in a receiving hole formed in a bottom surface of an arm that pivots as a cam rotates and having an internal thread on its inner periphery, an adjusting screw having an external thread on its outer periphery which is in threaded engagement with the internal thread of the nut member, and a return spring biasing the adjusting screw in a direction to protrude downwardly from the nut member, said adjusting screw having an end protruding from the nut member and pressing a valve stem of a valve gear, wherein said adjusting screw is a solid member, the lash adjuster further comprises a spring seat disposed between the adjusting screw and the return spring and kept in point contact with an end of the adjusting screw inserted in the nut member, and that the spring seat is axially slidably fitted in the inner periphery of the nut member, thereby keeping the adjusting screw and the spring seat coaxial with each other. 
     
     
         4 . The lash adjuster of  claim 1  wherein the spring seat has a fitting surface axially slidably fitted in the internal thread on the inner periphery of the nut member, said fitting surface having an axial length longer than a pitch of the internal thread. 
     
     
         5 . The lash adjuster of  claim 1  wherein the spring seat comprises a cylindrical portion fitted in the inner periphery of the nut member, and an end portion kept in point contact with the end of the adjusting screw inserted in the nut member, and wherein the return spring is inserted in the cylindrical portion of the spring seat. 
     
     
         6 . The lash adjuster of  claim 1  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is a flat surface. 
     
     
         7 . The lash adjuster of  claim 1  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is a concave spherical surface. 
     
     
         8 . The lash adjuster of  claim 1  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is also a convex spherical surface. 
     
     
         9 . The lash adjuster of  claim 2  wherein the spring seat has a fitting surface axially slidably fitted in the internal thread on the inner periphery of the nut member, said fitting surface having an axial length longer than a pitch of the internal thread. 
     
     
         10 . The lash adjuster of  claim 3  wherein the spring seat has a fitting surface axially slidably fitted in the internal thread on the inner periphery of the nut member, said fitting surface having an axial length longer than a pitch of the internal thread. 
     
     
         11 . The lash adjuster of  claim 2  wherein the spring seat comprises a cylindrical portion fitted in the inner periphery of the nut member, and an end portion kept in point contact with the end of the adjusting screw inserted in the nut member, and wherein the return spring is inserted in the cylindrical portion of the spring seat. 
     
     
         12 . The lash adjuster of  claim 3  wherein the spring seat comprises a cylindrical portion fitted in the inner periphery of the nut member, and an end portion kept in point contact with the end of the adjusting screw inserted in the nut member, and wherein the return spring is inserted in the cylindrical portion of the spring seat. 
     
     
         13 . The lash adjuster of  claim 2  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is a flat surface. 
     
     
         14 . The lash adjuster of  claim 3  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is a flat surface. 
     
     
         15 . The lash adjuster of  claim 2  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is a concave spherical surface. 
     
     
         16 . The lash adjuster of  claim 4  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is a concave spherical surface. 
     
     
         17 . The lash adjuster of  claim 2  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is also a convex spherical surface. 
     
     
         18 . The lash adjuster of  claim 3  wherein one of contact surfaces of the adjusting screw and the spring seat is a convex spherical surface and the other of the contact surfaces is also a convex spherical surface.