| abstract |
A rotary vane motor for efficiently extracting mechanical energy from an expanding gas at low rotational speeds is provided. The motor includes a housing having a cylindrical enclosure, a rotor having a plurality of radially oriented slots, a plurality of vanes slidably movable in the slots, a shaft for rotatably mounting the rotor in an eccentric position within the housing enclosure, and a slidable connection between the rotor and the shaft for equilibrating close clearances between the rotor and the side edges of the vanes and the inner surfaces of the housing to minimize inefficiencies due to blow-by and friction. Additionally, the materials forming the rotor, the vanes, and the housing are all selected to have the same thermal coefficient of expansion so that the vanes tightly interfit within their respective slots and the sealing surfaces of the housing over a temperature range spanning the cryogenic temperatures associated with the prefeffed drive gas, and maximum ambient temperatures. Finally, gas conducting structures in either the rotor or the vanes are provided for admitting a portion of the drive gas to the inner edges of the vanes to radially push the outer edges into tight sealing engagement with the inner surfaces of the housing. |