Abstract: A rotary control valve for an expansion fluid driven engine has a body with inlet and outlet ports and a distribution port communicating with an engine cylinder. A shaft in the body has first and second discs thereon and rotates in synchronization with reciprocation of the engine piston. The first disc has a pressure fluid passage therethrough and the second disc has an exhaust fluid passage therethrough. Sealing pistons in the body urge against the discs and have passages therethrough respectively connecting the pressure fluid passage with the inlet and distribution ports and the exhaust fluid passage with the distribution and outlet ports. The rotation of the discs alternately permits and stops flow of fluid to and from the cylinder.

Abstract: A rotary control valve for expansion fluid driven engines comprises a housing having inlet and outlet ports, a distribution port positioned at one end of the housing and communicating with the engine cylinder, and a first sealing face disposed about the distribution port. A rotor is mounted in the housing on a drive shaft, rotates therewith, and is capable of translating axially thereon. The rotor includes pressure and exhaust passageways which alternately communicate with the distribution port to pressurize and exhaust the engine cylinder. A second sealing face is positioned on the rotor about one end of the pressure and exhaust passageways, and mates with the housing sealing face to form a sliding seal therebetween. A seal ring is positioned between the periphery of the rotor and the housing, and divides the cavity defined therebetween into separate intake and exhaust chambers which respectively communicate with the intake and exhaust ports.