The invention relates to a rotary piston engine used as a combustion engine, wherein two/three eccentric pistons form a functional unit. The first piston is used to induce and compress the medium (fuel-air mixture), the second piston serves to expand the ignited and burned medium, while the third piston processes the residual gas. A closeable connection between both eccentric pistons is provided, in which ignition is carried out. The eccentric pistons are staggered in relation to each other. This construction enables easy manufacture of an engine which is more robust than the Otto engine.
