PTAB

IPR2017-00526

CulTec Inc v. StormTech LLC

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Molded Plastic Chamber
  • Brief Description: The ’583 patent discloses molded plastic, arch-shaped chambers for underground stormwater management. The chambers feature primary crest and valley corrugations for structural strength, which are enhanced with smaller, secondary "sub-corrugations" that terminate at varying heights along the chamber's arch.

3. Grounds for Unpatentability

Ground 1: Claims 1-21 are obvious over Cobb

  • Prior Art Relied Upon: Cobb (Patent 8,491,224).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Cobb, which also discloses an arched stormwater chamber, teaches nearly every element of the challenged claims. This includes a chamber with alternating crest and valley corrugations, where the crest corrugations narrow with increasing elevation and the valley corrugations widen. Cobb also expressly discloses applying secondary sub-corrugations to these primary corrugations to increase strength.
    • Motivation to Combine (N/A - Single Reference): The sole element Petitioner contended was missing from Cobb's express disclosure was the specific termination of the crest sub-corrugations at an elevation below the top of the chamber. Petitioner argued this modification was an obvious design choice based on Cobb’s own teachings. Cobb taught that sub-corrugations are most effective in the widest, flattest areas (near the base) and that valley sub-corrugations can "gradually fade out." A person of ordinary skill in the art (POSITA) would have been motivated to apply this same "fade out" concept to the crest sub-corrugations to reduce material costs and improve manufacturability by increasing the mold's draft angle for easier part ejection.
    • Expectation of Success: A POSITA would expect that terminating the crest sub-corrugations would predictably maintain structural integrity while improving manufacturing efficiency, as it involved applying a known technique (fading out corrugations) for a known purpose.

Ground 2: Claims 1-21 are obvious over Cobb in view of Fouss

  • Prior Art Relied Upon: Cobb (Patent 8,491,224) and Fouss (Patent 4,360,042).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground relied on Cobb for the fundamental chamber design, as in Ground 1. Petitioner asserted that Fouss, which discloses an earlier underground drainage chamber, explicitly teaches the use of strengthening corrugations that do not extend over the full arch of the chamber. Fouss discloses a hinge feature at the chamber's apex formed by a "simple lack of corrugations," demonstrating that terminated corrugations were known in the art.
    • Motivation to Combine: A POSITA seeking to optimize the design of Cobb's chamber would have looked to prior art solutions like Fouss. Fouss provided an explicit example that terminating strengthening features like sub-corrugations below the chamber's apex was a known and viable design approach for such products.
    • Expectation of Success: Because Fouss demonstrated that a chamber with interrupted corrugations was structurally sound and functional, a POSITA would have had a reasonable expectation of success in modifying Cobb's chamber to include crest sub-corrugations that similarly terminated below the top.

Ground 3: Claims 1-21 are obvious over Cobb in view of Ellis

  • Prior Art Relied Upon: Cobb (Patent 8,491,224) and Ellis (Patent 6,497,333).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground also used Cobb as the primary reference. Petitioner argued that Ellis provides teachings on strengthening curved plastic parts generally, disclosing the use of discontinuous, staggered grooves (equivalent to sub-corrugations) to increase the structural strength of cylindrical containers without substantially increasing material costs.
    • Motivation to Combine: Petitioner contended a POSITA would be motivated by cost and weight considerations to modify Cobb’s design by incorporating the discontinuous strengthening features taught by Ellis. Ellis’s teaching of staggering the discontinuous grooves to ensure continuous reinforcement was argued to be directly analogous to the staggered termination points of the crest and valley sub-corrugations claimed in the ’583 patent.
    • Expectation of Success: Ellis established that using discontinuous corrugations was a known technique for improving the strength of curved plastic parts. Therefore, a POSITA would have expected this known strengthening technique to work predictably when applied to the curved plastic chamber of Cobb.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge based on the combination of Cobb, Fouss, and Ellis. For claims 12 and 17, Petitioner also asserted obviousness over Cobb in view of November (Patent 2,876,801), which taught corrugations of constant width.

4. Key Technical Contentions

  • Manufacturability as a Design Driver: A central technical argument underpinning multiple grounds was that a POSITA would be highly motivated by manufacturing efficiencies inherent to injection molding. Petitioner argued that adding features like sub-corrugations increases the surface area in contact with the mold, making the part harder to eject. Terminating the sub-corrugations below the apex and tapering them improves the "draft angle," a well-known technique to facilitate easier release from the mold, reduce cycle times, and lower manufacturing costs. This provided a strong, practical motivation for the allegedly obvious modification.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-21 of the ’583 patent as unpatentable under 35 U.S.C. §103.