Sealed bearing drill bit with dual-seal configuration

• US 6,033,117 A
• Filed: 12/01/1997
• Issued: 03/07/2000
• Est. Priority Date: 12/19/1995
• Status: Expired due to Term

• Current Assignee: Sandvik Intellectual Property AB (Sandvik AB)
• Original Assignee: Smith International Incorporated (Schlumberger NV)
• Inventors: Cariveau, Peter, Cawthorne, Chris Edward, Didericksen, Roger, Slaughter, Robert H. Jr., Portwood, Gary Ray
• Primary Examiner(s): Walsh, Donald P.
• Assistant Examiner(s): RIVERA, WILLIAM ARAUZ
• Application Number:
  US08/982,081
• Time in Patent Office: 827 Days
• Field of Search: 384/92, 384/93, 384/94, 175/371, 277/92, 277/165
• US Class Current: 384/94
• CPC Class Codes: E21B 10/25 characterised by sealing details
• CPC Class Codes: F16C 19/49 Bearings with both balls and rollers
• CPC Class Codes: F16C 21/00 Combinations of sliding-contact bearings with ball or roller bearings, for exclusively rotary movement F16C17/24, F16C19/52 take precedence
• CPC Class Codes: F16C 2352/00 Apparatus for drilling in general E21
• CPC Class Codes: F16C 33/7836 floating with respect to both races
• CPC Class Codes: F16C 33/7896 with two or more discrete sealings arranged in series

Abstract

A sealed-bearing drill bit for use in an earthen annulus is provided having a dual seal arrangement. The drill bit includes at least one leg having a journal segment, and a roller cone mounted upon the journal segment and forming at least one bearing cavity therebetween. An annular primary seal is disposed between the leg and roller cone and between the bearing cavity and the earthen annulus. An annular secondary seal is disposed between the annular primary seal and the earthen annulus and is capable of substantially preventing the ingress of debris from the earthen annulus to the annular primary seal.

Claims

1. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus; and

an annular secondary seal disposed within an annular groove formed in said roller cone between said annular primary seal and the earthen annulus, wherein said annular secondary seal is primarily radially energized.

2. The drill bit of claim 1 wherein said annular secondary seal includes a sealing lip having a dynamic sealing surface.

3. The drill bit of claim 1 further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation.

4. The drill bit of claim 3 wherein said annular space is substantially filled with incompressible fluid.

5. The drill bit of claim 1 further including at least one bearing disposed within said bearing cavity, wherein the position of said annular primary seal along said central axis of said journal segment is closer to said bearing than is the position of said annular secondary seal along said central axis of said journal segment.

6. The drill bit of claim 5 wherein the axial extent of said annular primary seal at least partially overlaps the axial extent of said annular secondary seal.

7. The drill bit of claim 1 wherein at least one of said primary and secondary seals has a non-circular cross section.

8. The drill bit of claim 1 wherein said annular secondary seal includes a dynamic sealing surface constructed at least partially of elastomeric material.

9. The drill bit of claim 1 wherein said annular secondary seal is an O-ring seal constructed at least partially of elastomeric material.

10. The drill bit according to claim 9 wherein both of said primary and secondary seals are primarily axially energized.

11. The drill bit according to claim 1 wherein at least one of said primary and secondary seals is an absolute seal.

12. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus; and

an annular secondary seal disposed within an annular groove formed in said roller cone between said annular primary seal and the earthen annulus;

wherein the axial extent of said annular primary seal overlaps the axial extent of said annular secondary seal by at least approximately 15 percent of the total axial length of said annular primary seal.

13. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus; and

an annular secondary seal disposed within an annular groove formed in said roller cone between said annular primary seal and the earthen annulus;

wherein said annular secondary seal includes an O-ring having a non-circular cross section when said O-ring is its non-energized state.

14. The drill bit according to claim 13, further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation.

15. The drill bit according to claim 13 further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation and filled with an incompressbile fluid.

16. The drill bit according to claim 13 further including at least one bearing disposed within said bearing cavity, wherein the position of said annular primary seal along said central axis of said journal segment is closer to said bearing than is the position of said annular secondary seal along said central axis of said journal segment.

17. The drill bit according to claim 13 wherein the axial extent of said annular primary seal at least partially overlaps the axial extent of said annular secondary seal.

18. The drill bit according to claim 13 wherein said annular secondary seal includes a dynamic sealing surface constructed at least partially of elastomeric material.

19. The drill bit according to claim 13 wherein said annular secondary seal is an O-ring seal constructed at least partially of elastomeric material.

20. The drill bit according to claim 13 wherein said secondary seal is primarily radially energized.

21. The drill bit according to claim 13 wherein said secondary seal is primarily axially energized.

22. The drill bit according to claim 13 wherein said primary seal is an absolute seal.

23. The drill bit according to claim 13 wherein said secondary seal is an absolute seal.

24. The drill bit according to claim 13 wherein at least one of said primary and secondary seals is primarily radially energized.

25. The drill bit according to claim 13 wherein both of said primary and secondary seals are primarily radially energized.

26. The drill bit according to claim 13 wherein said primary seal is primarily axially energized.

27. The drill bit according to claim 13 wherein both of said primary and secondary seals are primarily axially energized.

28. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus, wherein said annular primary seal includes an O-ring having a non-circular cross section when said O-ring is its non-energized state; and

an annular secondary seal disposed within an annular groove formed in said roller cone between said annular primary seal and the earthen annulus.

29. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus; and

an annular secondary seal disposed within an annular groove formed in said roller cone between said annular primary seal and the earthen annulus, said annular secondary seal including a rigid, non-elastomeric annular ring having a dynamic sealing surface.

30. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said roller cone between said bearing cavity and the earthen annulus; and

an annular secondary seal disposed within an annular groove formed in said journal segment between said annular primary seal and the earthen annulus.

31. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within a first annular groove formed in said roller cone between said bearing cavity and the earthen annulus, said annular primary seal providing a substantially absolute seal; and

an annular secondary seal disposed within a second annular groove formed in said roller cone between said annular primary seal and the earthen annulus;

wherein said annular primary and secondary seals have different cross sections.

32. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween, said roller cone including a first annular groove disposed between said bearing cavity and the earthen annulus, and a second annular groove disposed between said first annular groove and the earthen annulus;

an annular primary seal disposed within said first annular groove; and

an annular secondary seal disposed within said second annular groove, wherein said annular secondary seal is primarily axially energized.

33. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween, said roller cone including a first annular groove disposed between said bearing cavity and the earthen annulus, and a second annular groove disposed between said first annular groove and the earthen annulus;

at least one bearing disposed in said bearing cavity;

an annular primary seal disposed within said first annular groove, said annular primary seal having a dynamic sealing surface; and

an annular secondary seal disposed within said second annular groove, said annular secondary seal having a dynamic sealing surface;

wherein said dynamic sealing surfaces of said annular primary seal and said annular secondary seal are at different radii from said central axis of said journal segment.

34. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween, said roller cone including a first annular groove disposed between said bearing cavity and the earthen annulus, and a second annular groove disposed between said first annular groove and the earthen annulus;

an annular primary seal disposed within said first annular groove; and

an annular secondary seal disposed within said second annular groove, wherein the axial extent of said annular primary seal at least partially overlaps the axial extent of said annular secondary seal.

35. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween, said roller cone including a first annular groove disposed between said bearing cavity and the earthen annulus, and a second annular groove disposed between said first annular groove and the earthen annulus;

an annular primary seal disposed within said first annular groove,

an annular secondary seal disposed within said second annular groove; and

an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation.

36. The drill bit according to claim 35 wherein said annular secondary seal includes a sealing lip having a dynamic sealing surface.

37. The drill bit according to claim 35 wherein said annular secondary seal includes a belleville spring type seal.

38. The drill bit according to claim 35 further including at least one bearing disposed within said bearing cavity, wherein the position of said annular primary seal along said central axis of said journal segment is closer to said bearing than is the position of said annular secondary seal along said central axis of said journal segment.

39. The drill bit according to claim 35 wherein the axial extent of said annular primary seal at least partially overlaps the axial extent of said annular secondary seal.

40. The drill bit according to claim 35 wherein at least one of said primary and secondary seals has a non-circular cross-section.

41. The drill bit according to claim 35 wherein said annular secondary seal includes a dynamic sealing surface constructed at least partially of elastomeric material.

42. The drill bit according to claim 35 wherein said annular secondary seal is an O-ring seal constructed at least partially of elastomeric material.

43. The drill bit according to claim 35 wherein at least one of said primary and secondary seals contains a rigid metal ring.

44. The drill bit according to claim 35 wherein at least one of said primary and secondary seals includes a rigid metal ring and said rigid ring has a dynamic surface that engages the cone.

45. The drill bit according to claim 35 wherein said secondary seal includes a rigid metal ring said annular secondary seal includes a biasing member that engages said rigid ring.

46. The drill bit according to claim 35 wherein said annular secondary seal includes a biasing member.

47. The drill bit according to claim 35 wherein said annular secondary seal includes a biasing member and said biasing member comprises an O-ring.

48. The drill bit according to claim 35 wherein said annular secondary seal includes a dynamic sealing surface that engages said cone.

49. The drill bit according to claim 35 wherein said annular secondary seal includes a dynamic sealing surface that engages said leg.

50. The drill bit according to claim 35 wherein at least one of said primary and secondary seals is primarily radially energized.

51. The drill bit according to claim 35 wherein both of said primary and secondary seals are primarily radially energized.

52. The drill bit according to claim 35 wherein at least one of said primary and secondary seals is primarily axially energized.

53. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

first and second annular interstices formed between said leg and said roller cone, said first annular interstice being disposed between said bearing cavity and the earthen annulus, said second annular interstice being disposed between said first annular interstice and the earthen annulus;

an annular primary seal disposed within said first annular interstice whereby sealing by said annular primary seal is primarily effected by energization of said annular primary seal between an opposed pair of energizing surfaces defining said first annular interstice, the remaining surfaces defining said first annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, and wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component; and

an annular secondary seal disposed within said second annular interstice whereby sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said second annular interstice, the remaining surfaces defining said second annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, and wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component.

54. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

at least one annular interstice formed between said leg and said roller cone and between said bearing cavity and the earthen annulus; and

an annular primary seal and an annular secondary seal both disposed within said annular interstice, said secondary seal being between said leg and said roller cone.

55. The drill bit according to claim 54 wherein said annular secondary seal includes a sealing lip having a dynamic sealing surface.

56. The drill bit according to claim 54, further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation.

57. The drill bit according to claim 54 further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation and filled with an incompressible fluid.

58. The drill bit according to claim 54 wherein at least one of said primary and secondary seals has a non-circular cross-section.

59. The drill bit according to claim 54 wherein said annular secondary seal includes a dynamic sealing surface constructed at least partially of elastomeric material.

60. The drill bit according to claim 54 wherein said annular secondary seal is an O-ring seal constructed at least partially of elastomeric material.

61. The drill bit according to claim 54 wherein at least one of said primary and secondary seals contains a rigid metal ring.

62. The drill bit according to claim 54 wherein at least one of said primary and secondary seals includes a rigid metal ring and said rigid ring has a dynamic surface that engages the cone.

63. The drill bit according to claim 54 wherein said secondary seal includes a rigid metal ring said annular secondary seal includes a biasing member that engages said rigid ring.

64. The drill bit according to claim 54 wherein said secondary seal is primarily radially energized.

65. The drill bit according to claim 54 wherein at least one of said primary and secondary seals is primarily radially energized.

66. The drill bit according to claim 54 wherein both of said primary and secondary seals are primarily radially energized.

67. The drill bit according to claim 54 wherein at least one of said primary and secondary seals is primarily axially energized.

68. The drill bit according to claim 54 wherein both of said primary and secondary seals are primarily axially energized.

69. The drill bit according to claim 54 wherein said annular secondary seal includes a biasing member.

70. The drill bit according to claim 54 wherein said annular secondary seal includes a biasing member and said biasing member comprises an O-ring.

71. The drill bit according to claim 54 wherein said annular secondary seal includes a dynamic sealing surface that engages said cone.

72. The drill bit according to claim 54 wherein said annular secondary seal includes a dynamic sealing surface that engages said leg.

73. The drill bit according to claim 54 wherein said primary seal is an absolute seal.

74. The drill bit according to claim 54 wherein said secondary seal is an absolute seal.

75. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

at least one annular interstice formed between said leg and said roller cone and disposed between said bearing cavity and the earthen annulus;

an annular primary seal disposed within said annular interstice such that sealing by said annular primary seal is primarily effected by energization of said annular primary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, and wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component; and

an annular secondary seal disposed within an annular groove formed in said roller cone between said annular primary seal and the earthen annulus.

76. The drill bit according to claim 75 wherein said annular secondary seal includes a sealing lip having a dynamic sealing surface.

77. The drill bit according to claim 75, further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation.

78. The drill bit according to claim 75 further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation and filled with an incompressible fluid.

79. The drill bit according to claim 75 wherein at least one of said primary and secondary seals has a non-circular cross-section.

80. The drill bit according to claim 75 wherein said annular secondary seal includes a dynamic sealing surface constructed at least partially of elastomeric material.

81. The drill bit according to claim 75 wherein said annular secondary seal is an O-ring seal constructed at least partially of elastomeric material.

82. The drill bit according to claim 75 wherein at least one of said primary and secondary seals contains a rigid metal ring.

83. The drill bit according to claim 75 wherein at least one of said primary and secondary seals includes a rigid metal ring and said rigid ring has a dynamic surface that engages the cone.

84. The drill bit according to claim 75 wherein said secondary seal includes a rigid metal ring said annular secondary seal includes a biasing member that engages said rigid ring.

85. The drill bit according to claim 75 wherein said secondary seal is primarily radially energized.

86. The drill bit according to claim 75 wherein at least one of said primary and secondary seals is primarily radially energized.

87. The drill bit according to claim 75 wherein both of said primary and secondary seals are primarily radially energized.

88. The drill bit according to claim 75 wherein at least one of said primary and secondary seals is primarily axially energized.

89. The drill bit according to claim 75 wherein both of said primary and secondary seals are primarily axially energized.

90. The drill bit according to claim 75 wherein said annular secondary seal includes a biasing member.

91. The drill bit according to claim 75 wherein said annular secondary seal includes a biasing member and said biasing member comprises an O-ring.

92. The drill bit according to claim 75 wherein said annular secondary seal includes a dynamic sealing surface that engages said cone.

93. The drill bit according to claim 75 wherein said annular secondary seal includes a dynamic sealing surface that engages said leg.

94. The drill bit according to claim 75 wherein said primary seal is an absolute seal.

95. The drill bit according to claim 75 wherein said secondary seal is an absolute seal.

96. The drill bit according to claim 75 wherein said annular secondary seal includes a belleville spring type seal.

97. The drill bit according to claim 75 further including at least one bearing disposed within said bearing cavity, wherein the position of said annular primary seal along said central axis of said journal segment is closer to said bearing than is the position of said annular secondary seal along said central axis of said journal segment.

98. The drill bit according to claim 75 wherein the axial extent of said annular primary seal at least partially overlaps the axial extent of said annular secondary seal.

99. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

at least one annular interstice formed between said leg and said roller cone and disposed between said bearing cavity and the earthen annulus;

an annular primary seal disposed within said annular interstice such that sealing by said annular primary seal is primarily effected by energization of said annular primary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, and wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component; and

an annular secondary seal disposed within an annular groove formed in said journal segment between said annular primary seal and the earthen annulus.

100. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular groove formed in said journal segment between said bearing cavity and the earthen annulus;

an annular primary seal disposed within said annular groove in said journal segment;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice such that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component, and wherein said annular secondary seal is primarily radially energized.

101. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular groove formed in said journal segment between said bearing cavity and the earthen annulus;

an annular primary seal disposed within said annular grooved formed in said journal segment;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice whereby sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, and wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component, said annular secondary seal having no unconnected elements.

102. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice such that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component, and wherein said annular secondary seal includes an O-ring having a non-circular cross section.

103. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus, wherein said annular primary seal includes an O-ring having a non-circular cross section;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice whereby sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component.

104. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice such that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component;

said annular secondary seal including a rigid, non-elastomeric annular ring, said annular ring having an L-shaped cross section and an annular elongated arm portion, said annular secondary seal further including an annular energizing member engageable with said annular ring, wherein the distance between said annular energizing member and said central axis of said journal segment is smaller than the distance between said annular elongated arm portion and said central axis of said journal segment.

105. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment, said journal segment having a central axis;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said journal segment between said bearing cavity and the earthen annulus;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice such that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component, said annular secondary seal including a rigid, non-elastomeric annular L-shaped ring, said annular L-shaped ring having an elongated arm portion and a dynamic sealing surface, said annular secondary seal further including an annular energizing member engagable with said annular L-shaped ring, wherein said dynamic sealing surface of said annular L-shaped ring engages said energizing surface on said roller cone.

106. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said roller cone between said bearing cavity and the earthen annulus;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus; and

an annular secondary seal disposed within said annular interstice such that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component, said annular secondary seal being primarily radially energized.

107. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said roller cone between said bearing cavity and the earthen annulus;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus;

an annular secondary seal disposed within said annular interstice whereby that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component; and

an annular space formed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation.

108. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed within an annular groove formed in said roller cone between said bearing cavity and the earthen annulus;

at least one annular interstice formed between said leg and said roller cone and between said annular primary seal and the earthen annulus;

an annular secondary seal disposed within said annular interstice such that sealing by said annular secondary seal is primarily effected by energization of said annular secondary seal between an opposed pair of energizing surfaces defining said annular interstice, the remaining surfaces defining said annular interstice being primarily non-energizing surfaces, said primarily non-energizing surfaces including first and second opposed non-energizing surfaces, wherein said first opposed non-energizing surface is a surface of said leg and said second opposed non-energizing surface is a surface of said roller cone, wherein no pair of opposed primarily non-energizing surfaces are surfaces of a single component, said annular secondary seal including a rigid, non-elastomeric annular ring having a dynamic sealing surface.

109. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a leg backface surface and a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed between said journal segment and said roller cone and between said bearing cavity and the earthen annulus; and

an annular secondary seal disposed within an annular groove formed in said leg backface surface between said annular primary seal and the earthen annulus.

110. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween, said roller cone including an annular groove; and

an annular primary seal and an annular secondary seal both disposed within said annular groove.

111. A drill bit for use in an earthen annulus, comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

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

an annular secondary seal disposed between said leg and said roller cone and between said annular primary seal and the earthen annulus, wherein said annular secondary seal includes first and second rigid annular rings comprising non-elastomeric material, said annular secondary seal further including at least one annular energizing member capable of energizing said first and second rigid annular rings.

112. A sealed bearing drill bit for use in an earthen annulus comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed between said leg and said roller cone and between said bearing cavity and the earthen annulus;

an annular secondary seal disposed between said annular primary seal and the earthen annulus, wherein said annular secondary seal is primarily radially energized; and

an annular space formed between said annular primary seal and said annular secondary seal, said annular space in complete fluid isolation.

113. The drill bit according to claim 112 wherein said annular secondary seal includes a sealing lip having a dynamic sealing surface.

114. The drill bit according to claim 112 further including an annular space disposed between said annular primary seal and said annular secondary seal, said annular space being in complete fluid isolation and filled with an incompressible fluid.

115. The drill bit according to claim 112 further including at least one bearing disposed within said bearing cavity, wherein the position of said annular primary seal along said central axis of said journal segment is closer to said bearing than is the position of said annular secondary seal along said central axis of said journal segment.

116. The drill bit according to claim 112 wherein the axial extent of said annular primary seal at least partially overlaps the axial extent of said annular secondary seal.

117. The drill bit according to claim 112 wherein at least one of said primary and secondary seals has a non-circular cross-section.

118. The drill bit according to claim 112 wherein said annular secondary seal includes a dynamic sealing surface constructed at least partially of elastomeric material.

119. The drill bit according to claim 112 wherein said annular secondary seal is an O-ring seal constructed at least partially of elastomeric material.

120. The drill bit according to claim 112 wherein at least one of said primary and secondary seals contains a rigid metal ring.

121. The drill bit according to claim 112 wherein at least one of said primary and secondary seals includes a rigid metal ring and said rigid ring has a dynamic surface that engages the cone.

122. The drill bit according to claim 112 wherein said secondary seal includes a rigid metal ring said annular secondary seal includes a biasing member that engages said rigid ring.

123. The drill bit according to claim 112 wherein said annular secondary seal includes a biasing member.

124. The drill bit according to claim 112 wherein said annular secondary seal includes a biasing member and said biasing member comprises an O-ring.

125. The drill bit according to claim 112 wherein said annular secondary seal includes a dynamic sealing surface that engages said cone.

126. The drill bit according to claim 112 wherein said annular secondary seal includes a dynamic sealing surface that engages said leg.

127. The drill bit according to claim 112 wherein said primary seal is an absolute seal.

128. The drill bit according to claim 112 wherein said secondary seal is an absolute seal.

129. A sealed bearing drill bit for use in an earthen annulus comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed between said leg and said roller cone and between said bearing cavity and the earthen annulus, said annular primary seal capable of providing a substantially absolute seal; and

an annular secondary seal disposed between said annular primary seal and the earthen annulus, said annular secondary seal being primarily radially energized;

wherein said annular primary seal and said annular secondary seal have different cross sections.

130. A sealed bearing drill bit for use in an earthen annulus comprising:

a bit body having at least one leg, said leg having a journal segment;

a roller cone rotatably mounted upon said journal segment and forming at least one bearing cavity therebetween;

an annular primary seal disposed between said leg and said roller cone and between said bearing cavity and the earthen annulus, said annular primary seal having a dynamic sealing surface; and

an annular secondary seal disposed between said annular primary seal and the earthen annulus, said annular secondary seal being primarily radially energized and having a dynamic sealing surface;

wherein said annular primary seal and said annular secondary seal have different peak contact pressures at their dynamic sealing surfaces.