Rotary expander

An improved expander of the type that is used to extract power from a supply of pressurized fluid and that includes:

• a housing:
• having a rotation axis;
• defining a hollow interior having an annular surface orientated parallel to the rotation axis and through which the rotation axis extends;
• and defining one or more ports which extend through the housing to the interior;
• a rotor mounted in the housing for rotation about the rotation axis, the rotor having
• a body having an outer tubular surface, the tubular surface having defined therein a plurality of voids;
• for each of the voids of the plurality, a vane, the vane:
• having a seal defining a tip of the vane;
• being mounted in the void for which it is provided for movement between a retracted position and an extended position;
• and being adapted such that, upon rotation of the rotor in the housing, movement of the vane between the extended and retracted positions causes the tip seal to sweep the annular surface;
• control means for controlling movement of the vanes and access to the ports such that the vanes create chambers which increase in volume when in communication with the source of pressurized fluid,
• the improvement comprising:
• for each vane, a pivot axis orientated parallel to the rotational axis and about which said each vane pivots between the extended and retracted positions.