Patent ID: 7377241

Claim:
A valve operating system for an internal combustion engine comprising: a pair of free rocker arms capable of swinging relative to each other and being free with respect to an engine valve, and a drive rocker arm which is linked and connected to the engine valve and sandwiched between both the free rocker arms are swingably supported at a rocker arm shaft which is common to both the free rocker arms and the drive rocker arm; a camshaft which rotates around an axis parallel with the rocker arm shaft is provided with a plurality of cams including cams individually corresponding to both the free rocker arms by making cam profiles differ from each other; and the drive rocker arm and both the free rocker arms are provided with valve operating characteristics changing means capable of changing operational characteristics of the engine valve by switching a connection of the drive rocker arm to both the free rocker arms and release of the connection; wherein the valve operating characteristics changing means comprises a single connection operating member which is provided in common at the drive rocker arm and both the free rocker arms to be capable of switching movement between an alternative connecting state of the drive rocker arm to either one of the free rocker arms and a release state of the connection of the drive rocker arm to the one free rocker arm, wherein a hydraulic pressure space is formed between the drive rocker arm and at least one of the pair of free rocker arms so as to extend in a direction of the switching movement of the single connection operating member, an end of the single connection operating member faces the hydraulic pressure space, a seal is provided between opposed faces of the driver rocker arm and the at least one free rocker arm to seal the hydraulic pressure space from an outside, and said single connection operating member is operated directly by a hydraulic pressure introduced into the hydraulic pressure space.