Undercut stator for a positive displacment motor

Patent metadata

Field	Value
Publication number	US-9393648-B2
Application number	US-74982810-A
Country	US
Kind code	B2
Filing date	Mar 30, 2010
Priority date	Mar 30, 2010
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A Moineau style stator includes a stator tube having a plurality of rigid helical lobes formed on an inner surface thereof. The helical lobes define a major internal tube diameter that is greater than a pass through diameter of the tube such that the major diameter undercuts the pass through diameter of the tube. A major liner diameter may also be less than the pass through diameter so as to provide a suitable interference fit between rotor and stator.

First claim

We claim:

1. A Moineau style stator comprising:
an integral stator tube including a longitudinal end having a threaded box end defining an internal pass through diameter;
the stator tube defining an internal helical cavity and further including a plurality of internal rigid helical lobes formed on an inner surface of the tube, the helical cavity having a major internal tube diameter that is greater than the pass through diameter of the longitudinal end; and
a resilient liner deployed on an inner surface of the stator tube and presented to the helical cavity,
wherein the resilient liner defines a major internal liner diameter that is less than the pass through diameter of the longitudinal end.

2. The stator of claim 1 , wherein the stator tube includes a box end having internal threads, the pass through diameter of the stator tube being equal to the internal thread diameter of the box end.

3. The stator of claim 1 configured for use in a pump or in a power section.

4. A subterranean drilling motor comprising:
a rotor having a plurality of rotor lobes on a helical outer surface of the rotor;
a stator including an integral stator tube, the stator tube including a longitudinal end having a threaded box end defining an internal pass through diameter, the stator tube defining an internal helical cavity and further including a plurality of rigid helical lobes formed on an inner surface of the tube, the helical cavity having a major internal tube diameter that is greater than the pass through diameter of the longitudinal end, the stator further including a resilient liner deployed on an inner surface of the stator tube and presented to the internal helical cavity, the resilient liner defining a major internal liner diameter that is less than the pass through diameter of the longitudinal end; and
the rotor deployable in the helical cavity of the stator tube such that an outer surface of the rotor is in a rotational interference fit with the resilient liner.

5. The stator tube of claim 4 , wherein the stator tube includes a box end having internal threads, the pass through diameter of the stator tube being equal to the internal thread diameter of the box end.

Assignees

• Underwood Lance D
• Murray William D
• Washburn Thomas K
• Smith International

Inventors

• Underwood Lance D
• Murray William D
• Washburn Thomas K

Classifications

• Y10T29/49229

  Prime mover or fluid pump making · CPC title

• B21K21/12

  Shaping end portions of hollow articles · CPC title

• F03C2/08

  of intermeshing-engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing · CPC title

• B23P15/00 Primary

  Making specific metal objects by operations not covered by a single other subclass or a group in this subclass · CPC title

• B23H3/04

  Electrodes specially adapted therefor or their manufacture (B23H9/00 takes precedence) · CPC title