Plastic hydraulic turbine

An axial flow water turbine comprising:

• a watertight housing having an inlet and an outlet through which water may flow;
• a rotor having a hub with a longitudinal axis, and turbine blades extending radially from the hub;
• an annular rim surrounding and connecting the blades of the rotor, the rim having a substantially cylindrical interior surface and an outer surface provided with plastic gear teeth made of a water lubricated plastic material having a low coefficient of friction;
• mounting means for rotatably mounting the rotor in the housing to secure the rotor against longitudinal and radial forces during operation, the mounting means including at least one bearing made of said plastic material, the bearing being coaxial with said longitudinal axis;
• at least one drive gear meshed wit the teeth of the annular rim to give drive to or obtain drive from the rotor, said at least one drive gear having teeth made of said plastic material;
• the housing further comprising:
• a substantially cylindrical inner shell having an upstream and a downstream portion coaxial with said longitudinal axis and aligned with the interior surface of the rim;
• a first compartment surrounding the outer surface of the rim and containing said at least one drive gear;
• and
• a second compartment surrounding said at least one bearing;
• a first annular upstream passage between the rim and upstream portion allowing water to pass between the shell and the first compartment;
• a second annular downstream passage between the rim and the downstream portion allowing water to pass between the shell and the first compartment, a flow through said shell causing a circulation of water in the first compartment by water passing in the first passage and out the second passage or in the second passage and out the first passage;
• a third annular passage between the hub and the mounting means allowing water to pass between the shell and the second compartment,
• whereby water passing through the housing fills the first and second compartments and provides lubrication for said plastic material.