| 摘要 |
An AC motor driven centrifugal pump includes an AC motor, a symmetrical pump volute, and an impeller shaft which is coupled to an impeller hub having a plurality of radial vanes or fins. The pump volute is symmetrical about a vertical axis with an axial inlet port and substantially tangential side walls feeding a radial outlet port. According to the invention, a movable gate is arranged between the impeller and the outlet port. The impeller hub is arranged axially with the inlet port and has a smaller diameter than the inlet port so that fluid entering the inlet port is free to flow around the impeller hub and into the spaces between the vanes. The gate is free to move and to rest against the interior of opposite tangential side walls of the volute. When the impeller begins to turn, the pivotal gate moved under the force of the fluid flow to rest against the opposite side wall blocking the passage of fluid backflow. The gate is free to move from one side wall to the other depending on the direction of rotation of the impeller. According to a preferred embodiment of the invention, a stationary baffle is located between the gate and the impeller to further streamline and direct the flow of fluid.
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