Linear actuator using magnetostrictive power element

• US 7,675,253 B2
• Filed: 04/11/2007
• Issued: 03/09/2010
• Est. Priority Date: 11/15/2006
• Status: Expired due to Fees

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Dorel, Alain P.
• Primary Examiner(s): MULLINS, BURTON S
• Application Number:
  US11/733,905
• Publication Number:
  US 20080111431A1
• Time in Patent Office: 1,063 Days
• Field of Search: 310/26, 318/118, 166/65.1, 166/66.4
• US Class Current: 318/118
• CPC Class Codes: E21B 34/066 electrically actuated
• CPC Class Codes: E21B 41/00 Equipment or details not covered by groups E21B15/00 - E21B40/00
• CPC Class Codes: H02N 2/023 Inchworm motors
• CPC Class Codes: H10N 35/00 Magnetostrictive devices integrated devices or assemblies of multiple devices H10N39/00

Abstract

A linear actuator includes a substantially cylindrical magnetostrictive element disposed in a housing. A retainer is cooperatively engaged with the housing and an exterior of the magnetostrictive element such that relaxed portions of the magnetostrictive element are frictionally retained in the retainer. An actuator rod is functionally coupled to one longitudinal end of the magnetostrictive element. A biasing device is disposed between the housing and the retainer to maintain the retainer in lateral compression. The actuator includes magnets arranged to induce peristaltic motion in the magnetostrictive element.

Claims

1. A method for operating a wellbore device, comprising:

applying inwardly radial biasing force to a retainer surrounding a substantially cylindrical magnetostrictive element to maintain frictional contact between the retainer and relaxed portions of the magnetostrictive element, wherein the applying inwardly radial biasing force comprises longitudinally biasing the retainer in a housing, the retainer and housing having cooperative surfaces arranged to radially compress the retainer in response to longitudinal biasing thereof in the housing;

applying a magnetic field to the magnetostrictive element to cause peristaltic motion in the magnetostrictive element; and

transferring the peristaltic motion at a longitudinal end of the magnetostrictive element to an operating element of the wellbore device.

2. The method of claim 1 wherein the applying a magnetic field comprises applying electric current to a plurality of wire coils wound longitudinally outside the retainer.

3. The method of claim 1 wherein the operating element comprises a back up pad on a formation testing instrument.

4. The method of claim 1 wherein the operating element comprises a back up arm on a density measuring instrument.

5. The method of claim 1 wherein the operating element comprises a steering element on a rotary steerable directional drilling instrument.

6. The method of claim 1 wherein the operating element comprises a wellbore sleeve valve.

7. The method of claim 1 further comprising passing a wellbore tubular longitudinally through the magnetostrictive element.

8. A method for operating a wellbore device, comprising:

applying inwardly radial biasing force to a retainer surrounding a substantially cylindrical magnetostrictive element to maintain frictional contact between the retainer and relaxed portions of the magnetostrictive element;

applying a magnetic field to the magnetostrictive element to cause peristaltic motion in the magnetostrictive element by applying electric current comprising multiphase alternating current to a plurality of wire coils wound longitudinally outside the retainer; and

transferring the peristaltic motion at a longitudinal end of the magnetostrictive element to an operating element of the wellbore device.

9. The method of claim 8 wherein the operating element comprises a back up pad on a formation testing instrument.

10. The method of claim 8 wherein the operating element comprises a back up arm on a density measuring instrument.

11. The method of claim 8 wherein the operating element comprises a steering element on a rotary steerable directional drilling instrument.

12. The method of claim 8 wherein the operating element comprises a wellbore sleeve valve.

13. The method of claim 8 further comprising passing a wellbore tubular longitudinally through the magnetostrictive element.