US Patent 7418933 Variable lift valve operating system for internal combustion engine

A variable lift valve operating system for an internal combustion engine, including a variable lift mechanism capable of changing a lift amount of an engine valve in accordance with rotation of a control shaft rotatably supported in a cylinder head, and an actuator which has an electric motor and power transmission means interposed between the electric motor and the control shaft, and which is connected to the control shaft. The actuator is constructed to have an oilless structure without oil supply, thereby always stably and rotationally driving the control shaft.