CYLINDRICAL LINEAR INDUCTION MOTOR FOR SUBMERGED PLUNGER PUMPS DRIVE Russian patent published in 2008 - IPC H02K41/25 F04B35/04 

FIELD: electric engineering.

SUBSTANCE: invention may be used in composition of pump plants for oil production. Movable secondary element-motor, made of thin-walled steel pipe with highly conducting coating applied on its internal surface, is installed between motionless casing and inductor. In case of alternate motion of thin-walled pipe - secondary element in casing volume of oil that flows from electric motor cavity from one side of inductor to the cavity of the other one is determined by volume of movable element and value of its travel. Since volume of movable thin-walled pipe of secondary element is by order less than the volume of inductor, volume of oil that flows through the opening in stator elements is significantly reduced and accordingly hydraulic resistance is decreased. For leveling oil pressure inside motor casing with ambient pressure and preservation of stable oil-filled volume of motor internal cavities, on one of casing covers stem is installed that is not connected to the secondary element and permits free travel in axial direction, and that changes position depending on position of traction stem that is connected to movable secondary element. This provides normal conditions of sliding seals operation, and accordingly reliable sealing.

EFFECT: reduction of hydraulic resistance to motion of movable parts and achievement of required sealing of internal cavities.

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