Submerged Hydroelectric Turbine Having Self-Powered Bearing Lubricant Circulation, Filtering, and Cooling System and Auto-Adaptive Pressure-Compensation System

Abstract

An underwater hydroelectric turbine comprises a turbine housing having an inlet and an outlet, a central shaft extending axially inside the turbine housing, a self-contained, sealed front bearing unit for rotationally supporting a front end of the central shaft, and a self-contained, sealed rear bearing unit for rotationally supporting a rear end of the central shaft. The front bearing unit and the rear bearing unit each comprises a self-powered lubricant circulation system that draws a fraction of the mechanical power from rotation of the central shaft to circulate lubricant through each respective bearing unit. The turbine may have an equilibrium chamber for automatically balancing lubricant pressure inside a lubricant-containing chamber of the bearing chambers with ambient water pressure outside the bearing housing.

1 . An underwater hydroelectric turbine comprising:
 a turbine housing having an inlet and an outlet;   a central shaft extending axially inside the turbine housing;   a self-contained, sealed front bearing unit for rotationally supporting a front end of the central shaft; and   a self-contained, sealed rear bearing unit for rotationally supporting a rear end of the central shaft;   wherein the front bearing unit and the rear bearing unit each comprises a self-powered lubricant circulation system that draws mechanical power from rotation of the central shaft to circulate lubricant through each respective bearing unit.   
     
     
         2 . The turbine as claimed in  claim 1  wherein the circulation system comprises a central axial channel through the central shaft extending from a front end of the central shaft to a pair of radial channels which are disposed closer to a geometrical center of the central shaft than is a bearing within each bearing unit, the radial channels delivering lubricant to an annular passageway that enables lubricant to flow through the bearing to continuously lubricate, clean and cool the bearing. 
     
     
         3 . The turbine as claimed in  claim 2  comprising an impeller connected to the central shaft, the impeller comprising impeller blades for circulating the lubricant. 
     
     
         4 . The turbine as claimed in  claim 2  or  claim 3  wherein the circulation system further comprises a filter for filtering the lubricant before the lubricant enters the central axial channel. 
     
     
         5 . The turbine as claimed in  claim 2  wherein the bearing unit comprises a nose portion into which lubricant flows to transfer heat through a housing wall into the ambient water outside the turbine to thereby cool the lubricant inside the turbine. 
     
     
         6 . The turbine as claimed in  claim 1  wherein the front bearing unit and the rear bearing unit each comprises:
 a sealing cartridge having a plurality of seals; and 
 a rigid cover enclosing the sealing cartridge to ensure that only static pressure acts against the seals of the sealing cartridge by inhibiting dynamic pressure fluctuation. 
 
     
     
         7 . The turbine as claimed in  claim 1  wherein the front bearing unit is axially movable with respect to the rear bearing unit. 
     
     
         8 . The turbine as claimed in  claim 7  wherein the front bearing unit comprises a bearing that slides within a bearing housing to enable axial displacement of the front bearing unit relative to the rear bearing unit. 
     
     
         9 . The turbine as claimed in  claim 1  wherein the front bearing unit and the rear bearing unit each comprises a dynamic rotating friction-type floating seal. 
     
     
         10 . The turbine as claimed in  claim 1  further comprising an equilibrium chamber for automatically equilibrating lubricant pressure inside a lubricant-containing chamber of the turbine with ambient water pressure outside the turbine. 
     
     
         11 . The turbine as claimed in  claim 2  wherein the bearing is a spherical roller bearing. 
     
     
         12 . The turbine as claimed in  claim 1  further comprising a magnetic candle in each of the front and rear bearing units to remove metallic debris from the lubricant. 
     
     
         13 . An underwater hydroelectric turbine comprising:
 a turbine housing having an inlet and an outlet;   a central shaft extending axially inside the turbine housing;   a self-contained, sealed front bearing unit for rotationally supporting a front end of the central shaft;   a self-contained, sealed rear bearing unit for rotationally supporting a rear end of the central shaft; and   an equilibrium chamber for automatically equilibrating lubricant pressure inside a lubricant-containing chamber of the turbine with ambient water pressure outside the turbine.   
     
     
         14 . The turbine as claimed in  claim 13  wherein the equilibrium chamber comprises a tank and a bladder having an elastic membrane within said tank, the bladder being pre-charged with a pressurized gas to expand and contract to balance the pressure inside the lubricant-containing chamber of the turbine with the ambient water pressure outside the turbine. 
     
     
         15 . The turbine as claimed in  claim 13  or  claim 14  comprising three successive annular chambers around the central shaft, wherein the three chambers comprise:
 a first chamber having a first seal to isolate the first chamber from ambient water; 
 a second chamber adjacent to the first chamber and having a second seal to isolate the second chamber from the first chamber; and 
 a third chamber adjacent to the second chamber and having a third seal to isolate the third chamber from the second chamber. 
 
     
     
         16 . The turbine as claimed in  claim 15  wherein the first chamber comprises a first equilibrium chamber, the second chamber comprises a second equilibrium chamber and the third chamber comprises a third equilibrium chamber. 
     
     
         17 . The turbine as claimed in  claim 16  wherein the third equilibrium chamber has a larger volume than the first equilibrium chamber, and wherein the first equilibrium chamber has a larger volume than the second equilibrium chamber. 
     
     
         18 . The turbine as claimed in  claim 15  wherein the third chamber has a larger volume than the first chamber, and wherein the first chamber has a larger volume than the second chamber. 
     
     
         19 . The turbine as claimed in  claim 15  wherein the third equilibrium chamber is disposed inside a nose portion of the third chamber. 
     
     
         20 . The turbine as claimed in  claim 15  wherein the first equilibrium chamber and the second equilibrium chamber are disposed outside the bearing housing. 
     
     
         21 . The turbine as claimed in  claim 13  comprising a lubricant oil pressure sensor. 
     
     
         22 . The turbine as claimed in  claim 13  comprising a humidity sensor and oil temperature sensor. 
     
     
         23 . The turbine as claimed in  claim 13  comprising a biaxial accelerometer for sensing vibrations in the turbine. 
     
     
         24 . The turbine as claimed in  claim 13  further comprising a forwardly extending submersible pressure transducer connected to a front lubricant manifold of the front bearing unit for sensing ambient water pressure. 
     
     
         25 . The turbine as claimed in  claim 13  further comprising a rearwardly extending submersible pressure transducer connected to a rear lubricant manifold of the rear bearing unit for sensing ambient water pressure.