PTAB

IPR2016-00521

John Crane Inc v. Finalrod IP LLC

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Sucker Rod and End Fitting
  • Brief Description: The ’162 patent discloses an end fitting for connecting fiberglass sucker rods used in oil extraction. The invention focuses on a wedge system within the fitting, comprising three distinct wedge-shaped cavities, designed to distribute compressive forces and minimize stress concentrations where the rod joins the fitting.

3. Grounds for Unpatentability

Ground 1: Obviousness over Rutledge and Strandberg - Claims 1, 6-11, 16-20, 25-28, 30 & 31 are obvious over Rutledge in view of Strandberg.

  • Prior Art Relied Upon: Rutledge (Patent 6,193,431) and Strandberg (Patent 4,475,839).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Rutledge taught the core concepts of a multi-wedge end fitting for sucker rods designed to manage stress, including using wedges with longer leading edges than trailing edges. While Rutledge disclosed embodiments with two to five wedges, Strandberg specifically disclosed a three-wedge design where each wedge has the same inner diameter at its narrowest part. Petitioner contended this combination taught the structure of the independent claims, including the "three wedge shaped portions" and each apex having an "equal dimension." Petitioner asserted that the claimed "force differential"—greater compressive force at the closed end—was not a unique feature but an inherent and natural result of any such wedge design, which Rutledge itself described as directing forces toward the end of the rod.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Rutledge's established wedge design principles with Strandberg's specific three-wedge configuration. Both references address the same well-known problem of distributing forces in sucker rod connections to prevent fatigue and failure. A POSITA would have seen it as an obvious design choice to implement Rutledge's stress-management concepts within the known and effective three-wedge framework taught by Strandberg.
    • Expectation of Success: A POSITA would have had a high expectation of success because the combination involved applying known design principles (from Rutledge) to a known structural configuration (from Strandberg) within the same field of art to achieve the predictable result of improved force distribution.

Ground 2: Obviousness over Rutledge, Strandberg, and Morrow - Claims 2-5, 12-15, 21-24, and 32-38 are obvious over Rutledge and Strandberg, further in view of Morrow.

  • Prior Art Relied Upon: Rutledge (’431 patent), Strandberg (’839 patent), and Morrow (Patent 4,662,774).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the combination in Ground 1, adding Morrow to teach the limitations in certain dependent claims regarding force distribution. Petitioner argued Morrow disclosed a three-wedge design where wedges progressively increase in size toward the open end by increasing the angle at the widest part. Morrow explicitly taught that a wider wedge (resulting from a smaller angle) accepts smaller compressive forces because the load is spread over a greater area. Petitioner asserted this directly taught the limitation that the compressive force on each wedge is inversely proportional to the length of its edge, as recited in claims like 2, 12, and 21.
    • Motivation to Combine: A POSITA, having already combined Rutledge and Strandberg, would have been motivated to incorporate Morrow's teachings on wedge geometry. Morrow directly addressed how to vary wedge size and angle to further optimize stress distribution, a primary goal in the field. Modifying the base design with Morrow's principles was a logical step to enhance performance and reduce fatigue.
    • Expectation of Success: The combination was a predictable application of known engineering principles, as Morrow provided explicit reasons for its wedge geometry—to enable different wedges to handle different load levels effectively.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 29 and 39 are obvious over Rutledge and Strandberg in view of Iwasaki (Patent 4,822,201) for its teachings on specific wedge length ratios, and that claim 40 is obvious over the same base combination in view of Rutledge ’560 (Patent 4,919,560) for its disclosure of progressively smaller taper angles.

4. Key Claim Construction Positions

  • "the compressive forces create a force differential...greater at the closed end...and decreasing toward the open end": Petitioner proposed this term should be construed to mean "the radial compressive forces are greater toward the closed end of the end fitting and decrease toward the open end." This construction was critical because Petitioner argued that such a radial force differential is an inherent property of the prior art wedge structures, rather than a novel, patentable feature.
  • "the maximum thickness is substantially constant and the minimum thickness is substantially constant": Petitioner argued this should be construed as "the maximum and minimum radial clearances (gaps or epoxy thicknesses)...may vary slightly from wedge-to-wedge." This construction allowed for minor variations, which Petitioner contended brought the structures disclosed in Rutledge and Strandberg within the scope of the claims.

5. Key Technical Contentions (Beyond Claim Construction)

  • Force Differential is an Inherent Property: Petitioner's central technical argument, woven through all grounds, was that the claimed force differential is not a result of a unique structure but is the natural, physical consequence of using any multi-wedge system in a sucker rod fitting. It was argued that due to the geometry and material properties of such fittings, the wedge closest to the rigid, closed end will necessarily experience greater radial compressive forces than wedges closer to the open end. Therefore, disclosing the structure that causes this effect (as the prior art allegedly did) is tantamount to disclosing the effect itself.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-40 of the ’162 patent as unpatentable under 35 U.S.C. §103.