| 主权项 |
1. A variable valve mechanism comprising:
a cam unit having a cylindrical shape and including a plurality of cams, the cam unit being provided around a camshaft; and a shift pin, wherein: any one of the plurality of cams provided in the cam unit is selected by engaging the shift pin, from an outside, with a guide groove provided on an outer periphery of the cam unit so as to slide the cam unit in an axial direction of the camshaft along with rotation of the camshaft; the guide groove includes a pair of guide portions provided on respective side surfaces of the guide groove in a width direction of the guide groove, the pair of guide portions projecting so as to face each other; the guide groove is configured such that the cam unit is slid toward a first side by relatively moving the shift pin toward a second side opposite to the first side with use of the guide portion on the first side in the pair of guide portions, and the cam unit is slid toward the second side by relatively moving the shift pin toward the first side with use of the guide portion on the second side in the pair of guide portions; the cam unit includes an immovable piece provided so as not to pivot relative to the cam unit and a movable piece provided so as to be pivotable relative to the cam unit; the guide groove is divided into two parts in the width direction of the guide groove, the guide portion on the first side is provided in the immovable piece, and the guide portion on the second side is provided in the movable piece; the movable piece is displaceable relative to the immovable piece between a first position and a second position, the first position being a position to which the movable piece pivots in a direction in which the camshaft rotates, and the second position being a position to which the movable piece pivots in a direction opposite to the direction in which the camshaft rotates; and a first urging member configured to urge the movable piece toward the first position is provided. |
