Slow rotating tool with gear reducer

Abstract

A slow rotating apparatus for use in performing downhole operations. The apparatus generally consists of a motor section with a rotor rotatable in response to fluid flow, a speed reducer section connected to the motor section such that an output speed of the speed reducer section is less than an output speed of the rotor, and a jetting section or other head attached to the speed reducer section and rotated thereby at the speed reducer output speed. A flow passage is defined through the speed reducer section so that fluid may communicate therefrom into the jetting head. The speed reducer section includes an input shaft attached to the rotor. The input shaft has an eccentric portion and has an input gear disposed about the eccentric portion. The input gear is a solid gear having a first outer geared surface and a second outer geared surface. The pitch diameter of the first outer geared surface is less than the pitch diameter of the second outer geared surface. A speed reducer body has a geared inner surface defined thereon in geared engagement with the first outer geared surface. A follower gear is disposed in the body and is in geared engagement with the second outer geared surface. Rotation of the input shaft causes the eccentric portion thereof to rotate in the input gear causing eccentric rotation of the input gear. Eccentric rotation of the input gear is translated into pure rotation by the follower gear which rotates the output shaft.

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