Abstract: This invention relates to an improvement in a rotary piston engine of trochoidal design, of the epitrochoidal or hypotrochoidal type with an outer envelope, with the piston surface and/or housing bore being equidistant to the mathematically exact trochoid, and including a follow-up drive, the improvement comprising that the minus-equidistant of the piston and/or of the housing bore has a value exceeding 10% of that of the generating radius and smaller that that for which the piston contour is tangent with the follow-up drive in the dead center positions.

Abstract: This invention relates to an improvement in a rotary piston machine of trochoidal construction for compressing a gaseous medium having working chambers between a trochoidal piston and a housing corresponding to the coordinated outer envelope curve, said working chambers being separated from each other by radial seals in the housing, and outlet openings closed-off by means preventing backflow for discharging medium from the working chambers, the improvement comprising trough-shaped recess means in the peripheral piston surface which, in the dead center position of the piston, are positioned immediately ahead of a radial seal.