INTERNAL COMBUSTION ENGINE VALVE GEAR MECHANISM CAM

PROBLEM TO BE SOLVED: To suppress release of coating due to the point contact of a driver with the side edge of a cylindrical surface of a cam at a time of switching a valve opening state to a valve closing state.SOLUTION: A cam 6 of a valve gear mechanism of an internal combustion engine used to drive an intake valve or an exhaust valve of the internal combustion engine to be opened or closed comprises: a cam lobe pressing a driver driving a valve body of the intake valve or the exhaust valve; a cylindrical surface 62a continuous to the cam lobe, constituting part of a base circle, and proximate to the driver; an inclined surface 62b located laterally to the cylindrical surface 62a, directed in a direction of inclining with respect to an axial direction, expanding along a circumferential direction; and a protective portion 62c obtained by chamfering a corner in which the cylindrical surface 62a crosses the inclined surface 62b or forming the corner into an R-corner and extending along a circumferential direction without interruption. 【課題】開弁状態から閉弁状態となる際に駆動体がカムの円筒面の側端縁に点線触することによるコーティングの剥離を抑止する。【解決手段】内燃機関の吸気バルブ又は排気バルブの開閉駆動に用いられる内燃機関の動弁機構用のカム６に、吸気バルブ又は排気バルブの弁体を駆動する駆動体を押圧するカムローブと、カムローブに連なりベースサークルの一部をなすとともに前記駆動体に対して近接する円筒面６２ａと、円筒面６２ａの側方に位置し軸方向に対して傾斜した方向を向き周方向に沿って拡張している傾斜面６２ｂと、前記円筒面６２ａと前記傾斜面６２ｂとが交わる角部を面取りし又は角部にＲを付けたものであり周方向に沿って途切れることなく延長している保護部６２ｃとを備える構成を採用する。【選択図】図２