Self relieving seal

• US 20060096782A1
• Filed: 12/19/2005
• Published: 05/11/2006
• Est. Priority Date: 04/03/2002
• Status: Active Grant

• Current Assignee: Smith International Incorporated (SLB)
• Original Assignee: Smith International Incorporated (SLB)
• Inventors: Griffo, Anthony, Cariveau, Peter T., Larsen, James L., White, Alysia C., Peterson, Steven W., Lockstedt, Alan, Neville, James L., Siracki, Michael, Bandi, Manikiran
• Granted Patent: US 7,201,241 B2
• Time in Patent Office: Days
• US Class Current: 175/57
• CPC Class Codes: E21B 10/25 characterised by sealing details
• CPC Class Codes: Y10S 277/926 Seal including fluid pressure equalizing or balancing feature
• CPC Class Codes: Y10S 277/928 Seal including pressure relief or vent feature

Abstract

Self relieving seals of this invention comprise an elastomeric seal body having a first sealing surface and a second sealing surface for contact with respective drill bit sealing surfaces. The seal includes a pair of external surfaces that each extend along the seal body between the first and second sealing surfaces. The seal includes one or more relief ports that are disposed through the seal body and that have openings through each of the seal body external surfaces. The relief port can be specially configured, e.g., have different diameter sections of constant or variable dimensions, to provide a degree of control over pressure equalization through the seal body when the seal is loaded within the drill bit. The seal may include an element, e.g., solid, tubular, or porous, disposed within the relief port to provide a further desired degree of control over pressure equalization through the seal when the seal is loaded within the drill bit. Surface features, on the seal or the drill bit, can be provided to offset the relief port opening from the rock bit so that it is not blocked off. The seal can include a valve mechanism to provide a further degree of control over fluid passage through the relief port.

Claims

1. An annular seal for use in a rotary cone drill bit having a body, a leg extending from the body, and a cutting cone rotatably mounted on the leg, the annular seal comprising:

a seal body formed from an elastomeric material, the seal body having;

a first sealing surface that is positioned against an adjacent sealing surface of the leg; and

a second sealing surface that is positioned against an adjacent sealing surface of the cone, wherein one of the first and second sealing surfaces forms a dynamic rotary seal against its respective leg or cone sealing surfaces; and

a pair of external surfaces each extending along the seal body between the first and second sealing surfaces; and

one or more relief ports disposed axially through the seal body and having openings through each of the seal body external surfaces.

2. The annular seal as recited in claim 1 wherein the relief port comprises two or more different diameter sections.

3. The annular seal as recited in claim 1 wherein the relief port comprises a first diameter section that extends into the seal body a distance from one seal body external surface, and a second diameter section that extends the other seal body external surface towards the first diameter section.

4. The annular seal as recited in claim 3 wherein the diameter sections are sized differently.

5. The annular seal as recited in claim 3 wherein the first diameter section has a constant diameter, and the second diameter section has a variable diameter.

6. The annular seal as recited in claim 1 wherein the seal body includes a tubular element that is at least partially disposed within the relief port, the tubular element having a central passage extending therethrough.

7. The annular seal as recited in claim 1 wherein the seal body is a one-piece construction and consists essentially of an elastomeric material.

8. The annular seal as recited in claim 1 wherein the body comprises a region of elastomeric material having a hardness that is different from that of another region of the body.

9. The annular seal as recited in claim 1 wherein the relief port includes an element disposed therein.

10. The annular seal as recited in claim 1 wherein the seal body includes a surface feature at the external surface that is position adjacent at least one of the relief port openings, and that has an increased surface area relative to the relief port opening.

12. The annular seal as recited in claim 1 further comprising a porous element connected with the seal body and in connection with the relief port.

13. The annular seal as recited in claim 1 wherein the seal body includes a raised surface feature positioned along at least one of the external surfaces adjacent the relief port opening.

14. The annular seal as recited in claim 1 further comprising a valve means in communication with the relief port to provide checked flow therethrough.

15. A rotary cone drill bit comprising:

a body having at least one leg extending therefrom;

cutting cones rotatably disposed on an end of the leg; and

one or more annular seals interposed between the cutting cone and leg and disposed within one or more respective seal glands, at least one seal comprising;

a seal body having a first sealing surface and a second sealing surface for contacting respective drill bit sealing surfaces, and a pair of external surfaces each extending along the seal body between the first and second sealing surfaces, the seal body formed essentially of an elastomeric material; and

one or more relief ports disposed axially through the seal body and having openings through each of the seal body external.

16. The drill bit as recited in claim 15 comprising two annular seals, wherein a first seal is positioned within the bit adjacent a journal bearing of the drill bit, and a second seal is positioned within the bit between the first seal and a bit external environment, wherein the second seal includes the one or more relief ports.

17. A rotary cone drill bit comprising:

a body having at least one leg extending therefrom, the leg having a journal segment;

a cutting cone rotatably disposed on the journal segment and forming a bearing cavity therebetween;

an annular primary seal disposed between the leg and roller cone;

an annular secondary seal disposed between the leg and roller cone, and positioned between the annular primary seal and a borehole, at least one of the seals comprising;

a seal body formed essentially from an elastomeric material and having a first sealing surface and a second sealing surface for contacting respective drill bit sealing surfaces, and a pair external surfaces each extending along the seal body between the first and second sealing surfaces; and

one or more relief ports disposed axially through the seal body and having openings through each of the seal body external surfaces.

18. The drill bit as recited in claim 17 wherein the at least one seal is the annular primary seal.

19. The drill bit as recited in claim 17 wherein the at least one seal is the annular secondary seal.

20. The drill bit as recited in claim 17 wherein the seal body has a one-piece construction.

21. A method for equalizing differential pressure imposed on an annular seal disposed within a rotary cone drill bit comprising the step of passing fluid or gas from a region of high pressure existing on one side of the seal to a region of relatively lower pressure existing on another side of the seal, through a relief port formed through an elastomeric body of the seal, wherein the relief port extends axially between external surfaces of the seal body, the seal body external surfaces existing between a seal body first sealing surface and a second sealing surface, wherein one of the seal body first and second sealing surfaces is positioned against a surface of a rotary cone, and the other of the seal body first and second sealing surfaces is positioned against a surface of a journal that projects outwardly from a leg extending from a drill bit body, wherein the cone is rotatably mounted on the journal.