Patent ID: 8122860

Claim:
A variable compression ratio internal combustion engine, comprising: a crankcase into which a crankshaft is assembled; a cylinder block in which a cylinder is formed and that is movably mounted on the crankcase; and camshafts disposed on two sides of the cylinder in the cylinder block so as to be rotatable in mutually opposite directions, wherein the camshafts include a shaft member, a cam member fixed to the shaft member, and a movable bearing member rotatably mounted on the shaft member, the cam member being rotatably housed in a cam housing hole, formed in one of the cylinder block and the crankcase, and the movable bearing member being rotatably housed in a bearing housing hole, formed in the other of the cylinder block and the crankcase, the camshafts are rotated to move the crankcase and the cylinder block toward or away from each other to change a compression ratio of the internal combustion engine, and as viewed from an axial direction of the camshaft, a length of a line segment joining a center of the shaft member, which is a center of rotation of the shaft member, and a center of the movable bearing member, which is a center of rotation of the movable bearing member within the bearing housing hole, is set longer than a length of a cam operating line segment, which is a straight line joining centers of the shaft member and the cam member, wherein a center of the cam member is a center of rotation of the cam member within the cam housing hole.