Patent attributes
An engine valve operating system is provided in which one end of a first link arm (61) turnably supported at a fixed position of an engine body and the other end of a second link arm (62) turnably supported by a displaceable movable shaft (68a) are turnably connected to a rocker arm (63) which has a cam abutting portion (65) abutting against a valve operating cam (69) and is interlocked and connected so as to apply a force in a valve opening direction to an engine valve (19) biased by a valve spring (24) in a valve closing direction. A rocker arm biasing spring (54) which is different from the valve spring (24) biases the rocker arm (63) in a direction in which the cam abutting portion (65) abuts against the valve operating cam (69). This ensures follow-up ability of the opening/closing operations and enables a reduction in the size of the system, while allowing the lift amount of the engine valve to vary continuously. It is also possible to improve the accuracy with which the lift amount is controlled when the engine valve is to be slightly opened.
