Valve operating system for multi-cylinder internal combustion engine

Abstract

A valve operating system in a multi-cylinder internal combustion engine, including an intake valve and an exhaust valve valve operating/stopping switch-over device capable of switching over the operation and non-operation or stoppage of an intake valve and an exhaust valve, respectively. Each valve operating/stopping switch-over device includes a hydraulic pressure chamber for exhibiting a hydraulic pressure force in one axial direction and a return spring for exhibiting a spring force in the other axial direction for opposing the hydraulic pressure force, so that the operation and stoppage of the intake and exhaust valves is switched over from one to another by controlling the hydraulic pressure applied to the hydraulic pressure chambers. A single hydraulic pressure control valve is connected commonly to the hydraulic pressure chambers in the intake valve and exhaust valve operating/stopping switch-over device. In one embodiment, spring loads of the return springs are set at values different from each other, and in another embodiment, the single hydraulic pressure control operates sequentially, for both embodiments to cause sequential operation of the intake and exhaust switch-over devices.