Two-stroke internal combustion engines

A supercharged two stroke internal combustion engine, having:

• a cylinder block and a cylinder head cooperating with at least one piston reciprocably received in a cylinder formed in said cylinder block to define at least one expansible combustion chamber,
• at least one intake valve slidably received in said cylinder head and cooperating with an intake valve seat to control air flow from an intake pipe into said chamber,
• at least one exhaust valve slidably received in said cylinder head and cooperating with an exhaust valve seat to control gas flow from said combustion chamber to an exhaust pipe,
• and means for operating said intake and exhaust valves in proper time sequence with the displacement of said piston, whereby both said valves are open while the piston is at its bottom dead center,
• said intake valve, intake pipe and cylinder head being so arranged and constructed to cause a progressively increasing non-uniform intake clearance opening oriented such that in response to opening movement of the said intake valve, the largest intake orifice area is developed at least initially closest to that portion of the wall of said cylinder must remote from said exhaust valve seat, so as to cause air to be directed toward the piston and substantially parallel to the wall of said cylinder upon opening of the intake valve and to thereby sheet-wise scavenge the chamber along a loop therein without substantial direct flow of air from the intake pipe to the exhaust pipe along the cylinder head.