Rich-core stratified charge spark ignition engine with rich mixture scoop

The combination in a four-stroke cycle internal combustion engine of means defining a closed end cylinder

• a piston reciprocable in said cylinder and defining therewith a variable volume combustion chamber at said cylinder closed end
• inlet and exhaust ports connecting with said cylinder at said closed end
• inlet and exhaust valves respectively associated with said ports and operable to close and open their connections with said cylinder, said inlet port and its associated inlet valve being arranged to direct incoming air in a swirling motion around the axis of said cylinder,
• a scoop extending downwardly from said cylinder closed end toward said piston, said scoop being spaced between the axis and wall of said cylinder and curved in a manner generally parallel with the curvature of said wall from a point adjacent said inlet valve toward said exhaust valve in the direction of inlet air flow, thus separating the swirling air mass into central core and annular peripheral portions,
• a spark plug in said cylinder defining means and having a spark gap in said combustion chamber adjacent the inner side of said scoop in said central core portion and
• means to establish in said central core portion of the combustion chamber a rich combustible fuel-air mixture for ignition by said spark plug.