Patent ID: 9745991
Date: 2017-08-29
CPC Classifications: F04D

Claim:
1. A submersible pump assembly, comprising: a centrifugal pump having a drive shaft extending along a longitudinal axis; a motor operatively coupled to the pump for rotating the drive shaft; the pump having a plurality of stages, each of the stages comprising: an impeller mounted to the drive shaft for rotation therewith and free to move axially relative to the shaft between downthrust and upthrust positions; a diffuser having a downward facing thrust surface; the impeller having a plurality of vanes, defining impeller passages extending upward and outward from a lower side of the impeller; an upward facing thrust surface on an upper side of the impeller positioned below the downward facing thrust surface of the diffuser; a plurality of balance holes in the impeller, each extending from the upper side of the impeller into one of the impeller passages; a thrust washer located between the upward facing thrust surface and the downward facing thrust surface, the thrust washer overlying the balance holes and being in engagement with both the upward facing thrust surfaces and the downward facing thrust surfaces while the impeller is in the upthrust position to transfer upthrust from the impeller to the diffuser; and at least one communication path at an interface between the thrust washer and the upward facing thrust surface to allow fluid flow through the balance holes during the upthrust position.