Title of Invention

A PUMP EXERTING A REDUCED AXIAL THRUST ON THE PUMP SHAFT

Abstract

A pump exerting a reduced axial thrust on the pump shaft comprising a pump housing accommodating a rotatable pump shaft on which the pump impellers are mounted; a rotatable disc mounted on the shaft above or between the impellers; a stationary sealing disc mounted in the housing just above the rotatable discJ the adjacent faces of the said two discs being in contact with each otherJ the space below the rotatable disc being exposed to pressure of the pumped flu id, while the space above the sealing disc communicates with the outside of the pump, through a passage in the housingJ and is thus exposed to pressure less than the pressure of the pumped fluidJ such pressure differential acting upwardly ,on the two discs, to lift the shaft correspondingly and reduce the axial thrust thereon.

Full Text

This invention relates to a pump exerting a reduced axial thrust on the pump shaft. This invention is especially useful in multistage pumps, such as, those used in bore-wells where the thrust load on the pump shaft can be very large. The pump proposed herein is so constructed that the normal thrust load on its shaft is substantially reduced. The pump exerting a reduced axial thrust on the pump shaft, according to this invention, comprises a pump housing accommodating a rotatable pump shaft on which the pump impellers are mounted; a rotatable disc mounted on the shaft above, or between, the impellers; a stationary sealing disc mounted in the housing just above the rotatable disc, the adjacent faces of the said two discs being in contact with each other, the space below the rotatable disc being exposed to pressure of the pumped fluid, while the space above the sealing disc communicates with the outside of the pump, through a passage in the housing, and is thus exposed to pressure less than the pressure of the pumped fluid, such pressure differential acting upwardly on the two discs, to lift the shaft correspondingly and reduce the axial thrust thereon. The pump proposed herein will now be described with reference to the accompanying drawings, which illustrate by way of example, and not by way of limitation, one of various possible embodiments of this invention Fig.l illustrating the embodiment in sectional elevation Fig.2 illustrating a variation of the embodiment with respect to the stationary and rotatable discs Fig.3 illustrating the rotatable disc as fixed to or integral with the top portion of the impeller as a variation of the said embodiment. The pump housing H accommodates a rotatable pump shaft S on which the pump impellers I are mounted. A rotatable disc Dl is mounted on the shaft S above the impellers (Fig.l). Alternatively this disc can be mounted between the impellers; or fixed to or integral with the top portion of an impeller (Fig.3). A stationary sealing disc D2 is mounted in the housing H just above the ro tat able disc Dl, the adjacent faces 1 and 2 of the said two discs being in contact with each other. These discs can have faces in the same plane or curved faces, as a variation (Fig. 2), to adjust for angular misalignment. The disc D2 seals off the fluid in the pump in the space below the said disc from the outside of the pump.The space above the disc D2 communicates with the outside of the pump through the passage P. The disc D2 is spring-loaded at F to ensure that the contact between the said two discs Dl and D2 is maintained to seal off the fluid in the pump from the outside. It will be seen from the foregoing description that the space below the rotatable disc Dl is exposed to pressure of the pumped fluid in the housing, while the space above the sealing disc D2 is exposed to the outside of the pump through the passage P above the disc D2 e.g. exposed to the atmosphere or to the external water column, as in a borewell. The pressure outside the pump being less than the pressure of the pumped fluid, the resulting pressure differential acts upwardly on the two discs, thus lifting the shaft S correspondingly to reduce the axial thrust thereon. The sealing disc D2, although stationary, is capable of a small axial displacement to adjust to the pressure differential acting on it, as aforesaid. The spring -loading at F will not be necessary if some leakage between the discs Dl and D2 is allowable. The terms and expressions in this specification are of description, and not of limitation, having regard to the fact that various other embodiments of the pump proposed herein are possible without departing from the scope and ambit of this invention. We Claim; 1. A pump exerting a reduced axial thrust on the pump shaft comprising a pump housing accommodating a rotatable pump shaft on which the pump impellers are mounted; a rotatable disc mounted on the shaft above or between the impellers; a stationary sealing disc mounted in the housing just above the rotatable disc, the adjacent faces of the said two discs being in contact with each other, the space below the rotatable disc being exposed to pressure of the pumped fluid, while the space above the sealing disc communicates with the outside of the pump, through a passage in the housing, and is thus exposed to pressure less than the pressure of the pumped fluid, such pressure differential acting upwardly on the two discs, to lift the shaft correspondingly and reduce the axial thrust thereon. 2. A pump as claimed in Claim 1 wherein the sealing disc is loaded by a spring exerting a downward force on the said disc. 3. A pump as claimed in Claim 1 or Claim 2 wherein the rotatable disc and the sealing disc have contacting surfaces in the same plane. 4. A pump as claimed in Claim 1 or Claim 2 wherein the rotatable disc and the sealing disc have contacting surfaces which are curved or otherwise not in the same plane. 5. A pump as claimed in any one of the preceding Claims wherein the rotatable disc is fixed to, or integral with, the top of an impeller. 6. A pump as claimed in any one of the preceding Claims wherein the sealing disc, although stationary, is capable of a small axial displacement to adjust to the pressure differential acting on it 7. A pump exerting a reduced axial thrust on the pump shaft substantially as herein described and illustrated with reference to the accompanying drawings.

Documents:

596-che-2003-claims.pdf

596-che-2003-correspondence others.pdf

596-che-2003-correspondence po.pdf

596-che-2003-description complete.pdf

596-che-2003-drawings.pdf

596-che-2003-form 1.pdf

596-che-2003-form 19.pdf

596-che-2003-form 26.pdf