PTAB

IPR2020-00520

Cobham Mission Systems Davenport LSS Inc v. Air Liquide Advanced Technologies US LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Integrated Membrane Filter
  • Brief Description: The ’513 patent discloses a gas separation module that integrates a filter medium within the module’s shell, upstream of a selectively gas permeable membrane. The internal filter is designed to remove gaseous contaminants from a feed gas mixture, thereby preventing damage to the membrane and extending the module's operational life in a compact and lightweight configuration.

3. Grounds for Unpatentability

Ground 1: Obviousness over Prasad in view of Tamura - Claims 1-2, 4-7, 10, 13-14, 18 are obvious over Prasad in view of Tamura.

  • Prior Art Relied Upon: Prasad (Patent 4,881,953) and Tamura (Patent 5,158,584).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Prasad taught all elements of the independent claims except for the physical integration of the filter within the membrane module shell. Prasad disclosed a system for preventing membrane degradation by using an external, upstream adsorbent trap (specifically activated carbon) to remove heavy hydrocarbon vapors from a feed gas before it reached the membrane separation unit. Tamura disclosed an oxygen-enriching module that explicitly taught positioning an air filtering element inside the same housing as the gas separation membrane to protect the membrane from contamination. Dependent claims were allegedly met by Prasad’s teaching of activated carbon filters and Tamura’s disclosure of specific module structures like tube sheets.
    • Motivation to Combine: A POSITA would combine Prasad’s effective, but external, contaminant removal system with Tamura’s integrated, space-saving design. Tamura provided the explicit motivation to make the module “small and lightweight,” which would be achieved by moving Prasad’s proven external filter inside the module housing as demonstrated by Tamura. This combination applies a known filtering technique (Prasad) to a known compact module configuration (Tamura) to achieve predictable results.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because Tamura demonstrated that a protective filter could be functionally integrated within a membrane module without negatively impacting performance. Moving Prasad's filter inside the housing was presented as a simple design choice with predictable benefits in size and weight, without altering the fundamental filtering function.

Ground 2: Obviousness over Suzuki in view of Prasad - Claims 1-2, 4-7 are obvious over Suzuki in view of Prasad.

  • Prior Art Relied Upon: Suzuki (Japanese Laid-open patent disclosure S59-87019) and Prasad (Patent 4,881,953).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Suzuki disclosed an oxygen enrichment apparatus that met most claim limitations by teaching a gas-adsorption filter integrated within the intake port of the module’s main body (shell), upstream of the gas-permselective membrane. This filter removed harmful gases like sulfur dioxide. However, Suzuki did not explicitly state that these specific contaminants degraded the membrane. Prasad remedied this by teaching that heavy hydrocarbon vapors are known to degrade membrane performance and that an activated carbon filter is the solution.
    • Motivation to Combine: A POSITA, aware of Suzuki's integrated filter design, would be motivated by Prasad to ensure protection against a wider range of known harmful contaminants. Knowing from Prasad that hydrocarbon vapors degrade membranes, a POSITA would modify Suzuki’s system by either substituting Suzuki’s gas-adsorption filter with Prasad’s activated carbon filter or adding Prasad's filter to the system. This modification would use a known solution (Prasad's filter) to address a known problem (membrane degradation from hydrocarbons) in a similar device (Suzuki's module).
    • Expectation of Success: The combination was argued to be a simple substitution of one known filter element for another to protect against a different, but known, type of contaminant. Since Suzuki already taught the utility of an integrated upstream filter, a POSITA would expect that incorporating a filter for hydrocarbons, as taught by Prasad, would predictably protect the membrane from that specific threat.

  • Additional Grounds: Petitioner asserted that claims 1-7, 9-15, and 18 are obvious over Tamura in view of Nakamura (Patent 4,259,096), Muraoka (Patent 5,772,738), and Prasad. This ground focused on substituting Tamura's dust filter with an activated carbon cloth filter, as taught by Nakamura and Muraoka, for the purpose of removing gaseous contaminants as motivated by Prasad.

4. Key Claim Construction Positions

  • Petitioner argued for a broad construction of the terms “the filter medium positioned between the shell and the membrane” (claim 1) and “a filter medium within the shell” (claim 4).
  • The proposed construction was that these terms should encompass a filter located anywhere inside the module’s overall housing, including in an end cap region, and upstream of the membrane. Petitioner contended this construction was necessary to avoid excluding the patent’s preferred embodiment (Fig. 1), where the filter is shown in a feed chamber created by an end cap rather than being physically wrapped around the membrane bundle. This broader reading was essential for mapping the prior art, which also showed filters in the inlet/end cap area of a module.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under §325(d) was inappropriate, even though the Prasad reference was considered during the original prosecution of the ’513 patent.
  • The core arguments were that the Examiner only ever used Prasad as a secondary reference to reject a group of dependent claims and never considered it as a primary reference against the independent claims. Petitioner asserted that its new invalidity grounds rely on Prasad in materially different combinations (with Tamura and Suzuki) and for different purposes than those considered by the Examiner. The arguments presented in the petition were framed as fundamentally different from the prosecution history, which focused on the inapplicability of an activated carbon filter to a system with liquid contaminants.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-7, 9-15, and 18 of the ’513 patent as unpatentable.