Valve system in a rotary radial-piston engine

A valve system for a radial-piston engine, comprising a stationary housing (2), a drive shaft (10) which is rotationally mounted essentially centrally inside said housing and which supports a hub (11) co-rotating therewith, at least two radially projecting cylinders (14) which are mounted on the hub to rotate therewith, said cylinders forming, together with the hub (11) and the drive shaft (10), a rotary unit arranged to rotate relative to the stationary housing (2), a combustion chamber (25) being formed in said hub (11) and having valve-operated inlets and outlets (26, 27) for intake and exhaustion, respectively, of a combustion fuel-air mixture and combusted exhaust gases, said inlets and outlets (26, 27) to and from, respectively, each combustion chamber (25) being formed axially in a valve ring (28) which co-rotates with the hub (11) and which is essentially concentric therewith, said valve ring (28) sealingly abutting against a stationary port ring (30) which is essentially concentric with the valve ring and which is connected to the housing (2), said port ring (30) being formed with axial intake and exhaust ports (36, 37) communicating with inlet and outlet ducts (34, 35), said axial intake and exhaust ports (36, 37) assuming, upon rotation of said rotary unit (10, 11, 14, 16) relative to the housing (2) a position in alignment with that inlet and outlet (26, 27) in the valve ring (28) that is associated with the respective combustion chamber (25) whereby the valve ring (28) is yieldingly pressed into abutment against said port ring (30), characterized in that at least one of the two faces in sliding contact with each other on respectively the valve ring (128) and the port ring (130) is provided with recesses (128a) distributed across said face.