Valve operating system for internal combustion engine

A valve operating system for an internal combustion engine, comprising an intake rotary valve and an exhaust rotary valve separately disposed in an intake passage and an exhaust passage, respectively, which independently communicate with a combustion chamber defined between a piston and a cylinder head in an internal combustion engine, said valves including spherical valve bodies adapted to open and close said intake and exhaust passages, respectively, and a valve operating mechanism having an intermittent operating function of rotatively driving said valve bodies of said intake and exhaust rotary valves in response to movement of said piston to provide an opening and closing control for said intake and exhaust rotary valves, and holding said rotary valve bodies in valve-opening and closing positions for respective predetermined periods of time, wherein said valve operating mechanism includes cam means adapted to be continuously rotated in one direction in response to the movement of said piston, rocker arms abutting said cam means and adapted to swing within a predetermined angle in accordance with the rotation of said cams, and rotary shafts each having one of said spherical valve bodies secured to one of the opposite ends thereof and adapted to reciprocally rotate between the valve-opening and closing positions of the valve body around an axis of said rotary shaft in accordance with the swinging movement of said rocker arm upon receiving a driving force from said rocker arm on the other end thereof, and said spherical valve bodies being each supported within said cylinder head through a valve seat member, and a seal spring being interposed between said valve seat member and the cylinder head.