Pressure Compensation System for a Motor Bearing Assembly
AssigneeNational Oilwell Varco, L.P.
InventorNicholas Marchand
Life of this patent
Estimating the term…
Abstract
In an oil-sealed bearing assembly in the bearing section of a mud motor, in which a mandrel is rotatably disposed within a cylindrical housing, a cylindrical sleeve is disposed coaxially within the mandrel with the sleeve being non-rotatably mounted to an inner surface of the mandrel, thereby forming an annular piston chamber forming part of a generally annular oil reservoir. An annular piston is axially movable within the piston chamber without rotation relative to either the mandrel or the sleeve.
Claims18
A mud motor bearing section having an upper end and a lower end, the bearing section comprising:
- a mandrel rotatably and coaxially disposed within a cylindrical housing having a longitudinal axis, the mandrel having an outer surface, and the housing having an inner surface;
- a cylindrical sleeve having an outer cylindrical surface, the sleeve being disposed within an inner cylindrical surface of the mandrel, the sleeve being coupled to the mandrel to form an annular piston chamber between the outer surface of the sleeve and the inner cylindrical surface of the mandrel;
- and
- an annular piston non-rotatingly disposed within the piston chamber, wherein the piston is adapted to move axially within the piston chamber, with the piston having an inner face sealingly engaging the outer surface of the sleeve, and an outer face sealingly engaging the inner cylindrical surface of the mandrel.
A bearing section for a mud motor having an upper end and a lower end, the bearing section comprising:
- a mandrel rotatably and coaxially disposed within a cylindrical housing having a longitudinal axis, the mandrel having an outer surface, and the housing having an inner surface;
- a cylindrical sleeve having an outer cylindrical surface, the sleeve being disposed within an inner cylindrical surface of the mandrel, with the sleeve mounted to the mandrel to form an annular piston chamber between the outer surface of the sleeve and the inner cylindrical surface of the mandrel;
- an annularly-configured piston disposed within the piston chamber;
- and
- an annular oil reservoir having a first portion bounded by the outer surface of the mandrel and the inner surface of the housing, and a second portion in the annular piston chamber, wherein the first portion is fluidly coupled to the second portion by a port through the mandrel.
A method for providing a shortened mud motor bearing section, the method comprising:
- rotatably and coaxially disposing a mandrel in a cylindrical housing;
- mounting a cylindrical sleeve within the mandrel;
- forming an annular piston chamber between an outer surface of the sleeve and an inner surface of the mandrel;
- and
- disposing an annular piston in the annular piston chamber for axial movement therein.
Dependencies are inferred from the claim text.