Variable valve-operating system for internal combustion engine

Abstract

A variable valve-operating system for an internal combustion engine, comprising a cylinder head having an intake or exhaust valve, a camshaft rotatably supported by the cylinder head, a cam body rotatably fitted around the camshaft and including a cam lobe having an outer peripheral surface for driving the valve and a boss protruding radially from the cam body, and a valve open period-varying mechanism supported on the camshaft and including an intermediate rotating member having a center of rotation offset from the camshaft, the mechanism transmits rotation of the camshaft to the boss of the cam body through the intermediate rotating member and also permits the valve open period of the valve to be varied through adjustment of the eccentric phase angle of the intermediate rotating member, wherein at least a part of the boss is so positioned as to overlap with the profile of a nose of the cam lobe when viewed in the axial direction of the cam body.

1 . A variable valve-operating system for an internal combustion engine, comprising:
 a cylinder head having an intake or exhaust valve;   a camshaft rotatably supported by the cylinder head;   a cam body rotatably fitted around an outer peripheral surface of the camshaft, the cam body including a cam lobe having an outer peripheral surface for driving the valve, and a boss protruding radially outward from an end portion of the cam body; and   a valve open period-varying mechanism supported on the camshaft and including an intermediate rotating member having a center of rotation offset from an axis of the camshaft, the valve open period-varying mechanism being adapted to transmit rotation of the camshaft to the boss of the cam body through the intermediate rotating member and also permitting a valve open period of the valve to be varied through adjustment of an eccentric phase angle of the intermediate rotating member,   wherein at least a part of the boss is so positioned as to overlap with a profile of a nose of the cam lobe when viewed in an axial direction of the cam body.   
   
   
       2 . The variable valve-operating system according to  claim 1 , wherein the boss is so positioned as to be located inside of the profile of the nose of the cam lobe when viewed in the axial direction of the cam body.