Submersible motor pump assembly

摘要

A submersible motor pump assembly has a motor which is installed at a level below the pump. The shaft which is driven by the motor and rotates the impeller or impellers of the pump is spacedly surrounded by a tubular member of a thermal barrier in the region between the upper end of the motor housing and the lower end of the pump casing. The solid impurities, especially magnetizable particles, which are circulated by the pump tend to penetrate into the motor housing by way of the clearance between the tubular member and the shaft, and the penetration of such impurities into the motor housing is prevented by an apparatus which conveys a stream of liquid from the discharge nozzle of the pump casing into the clearance and contains a filter with several electromagnets which intercept magnetizable particles and allow a clean stream of flushing liquid to flow into the clearance. A portion of the liquid stream which is admitted into the container of the filter and is laden with intercepted and/or non-segregated impurities is returned into the interior of the pump casing by way of channels which are machined directly into the tubular member and discharge contaminated liquid into the range of impeller means in the pump casing. The electromagnets of the filter can be energized independently of each other and are normally energized for a given interval of time including a period prior to starting of the motor and a period following the starting and corresponding to the period of run-up of the motor.