Patent ID: 9574465
Date: 2017-02-21
CPC Classifications: F01L

Claim:
1. A valve gear of an engine, comprising: a camshaft having a shaft portion and a cam element portion, the cam element portion being coupled to the shaft portion so as to rotate integrally with the shaft portion and to move in an axial direction of the shaft portion; and an operational device operative to move the cam element portion of said camshaft in the axial direction relative to the shaft portion, wherein said cam element portion comprises two cam portions for each valve which have a common base circle and different-shaped nose portions, which are provided adjacently to each other in the axial direction, the two cam portions operative to control opening/closing of the valve being configured to be switchable when moved in the axial direction on the shaft portion, said cam element portion further comprises a pair of end-face cams which are provided at both-end faces, in the axial direction, of the cam element portion, each of the end-face cams having a lift portion which is configured to project in the axial direction such that the amount of projection of the lift portion increases gradually along a rotational direction of the cam element portion in a specified phase range, said operational device comprises a first operational member which is arranged on one side of said cam element portion and a second operational member which is arranged on the other side of the cam element portion, the first operational member being configured to be driven by an actuator so as to take an operative position in which the first operational member projects to a position facing one of the end-face cams which is located on an arrangement side of the first operational member and contacts the lift portion of said one of the end-face cams so as to move the cam element portion along the shaft portion toward said other side of the cam element portion and a retreat position in which the first operational member retreats from said position facing the one of the end-face cams, the second operational member being configured to be driven by an actuator so as to take an operative position in which the second operational member projects to a position facing the other of the end-face cams which is located on an arrangement side of the second operational member and contacts the lift portion of said other of the end-face cams so as to move the cam element portion along the shaft portion toward said one side of the cam element portion and a retreat position in which the second operational member retreats from said position facing the other of the end-face cams, and said cam element portion is configured such that respective maximum lift portions of the pair of end-face cams are provided at respective phases which are different from each other in the rotational direction and that the maximum value of a length, in the axial direction, between respective cam faces of the pair of end-face cams which are provided at the same phase is less than or equal to a distance in the axial direction between a contact of the first operational member with the one of the end-face cams and a contact of the second operational member with the other of the end-face cams.