To prevent water condensed inside a cylinder at the time of a low temperature such as a starting time and water supplied as lubricating oil from being confined within the cylinder, in a rotary fluid machine driving a piston fitted into a cylinder formed radially on a rotor by high temperature and high pressure steam and rotating the rotor by reaction that the piston receives from a casing.
An annular drain groove 121 is formed in the vicinity of a radial direction outer end part of a cylinder member 39 formed radially on a rotor 31. When a piston 41 reaches the vicinity of a top dead center, water within the cylinder member 39 is held in the drain groove 121 (Referring to (A)). When the piston 41 reaches the vicinity of a bottom dead center at the end of steam discharge stroke, water stored in the drain groove 121 is discharged to a rotor chamber 14 because the drain groove 121 is opened by the piston 41 (Referring to (B)).
HONMA KENSUKE
HORIMURA HIROYUKI
ENDO TSUNEO
