Abstract: In known valve arrangements with flat slide valves the inlet valve and outlet valve of a cylinder are formed by a single flat slide which includes two small, sickle-shaped slots which are alternately brought to coincidence with the inlet port and the outlet port of the cylinder. The small, sickle-shaped slots make it more difficult to fill in the fuel mixture and to exhaust the combustion gases. According to the invention, a separate flat slide is respectively arranged as an inlet valve and an outlet valve of a cylinder, the slide having a closed flat slide surface and being movable between a retracted opening position and an extended closing position. The total surface of the inlet port and the outlet port can thereby be increased to 60 to 90% of the inner cross-sectional area of the cylinder, whereby an optimum cylinder filling and removal of the combustion gases are made possible. The opening lift of the flat slide valve of the inlet port is variable.

Abstract: A valve apparatus for an internal combustion engine includes an intake valve plate and an exhaust valve plate mounted side-by-side for longitudinal reciprocable, slidable movement over the mouth or opening of the combustion cylinder. Each of the slidable valve plates includes a plurality of longitudinally spaced movable valve ports which are adapted to register with corresponding fixed valve ports in the valve head on the opposite side of the slidable valve plates from the engine cylinder.