PTAB

IPR2018-01110

BalDwin Filters Inc v. Donaldson Co Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method of Making an Air Filter Cartridge
  • Brief Description: The ’700 patent discloses methods for manufacturing an air filter cartridge. The methods involve applying a curable resin to circumscribe a filter media pack to form a cured-in-place coating and providing the cartridge with a molded housing seal around the media pack.

3. Grounds for Unpatentability

Ground 1: Obviousness over Wydeven427 and Holzmann - Claim 34 is obvious over Wydeven427 in view of Holzmann.

  • Prior Art Relied Upon: Wydeven427 (Patent 4,410,427) and Holzmann (Patent 6,568,540).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Wydeven427, a fluid filtering device patent, disclosed nearly all limitations of claim 34. This included a method of manufacturing an air filter cartridge with a fluted media pack, applying a curable resin (e.g., urethane or silicone rubber) to form an impervious barrier circumscribing the media pack, and curing it in place. However, Petitioner contended that Wydeven427 did not explicitly teach that the housing seal is "molded" or located "around the media pack." Holzmann was introduced to supply these missing elements, as it taught providing a filter with a molded gasket member that extends around the filter media pack.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references because Holzmann showed that molding housing seals around the media pack was a conventional technique for air filter cartridges. The motivations included creating an integrated gasket, reducing the required housing closure force, and preventing the bypass of unfiltered air. A POSITA would have found it obvious to substitute Wydeven427's seal with Holzmann's well-known molded seal to achieve these predictable benefits.
    • Expectation of Success: A POSITA would have had a high expectation of success, as the combination involved substituting one known type of filter seal for another to perform the same function in a predictable manner.

Ground 2: Obviousness over Wydeven427, Holzmann, and Millington - Claims 34 and 38 are obvious over Wydeven427 in view of Holzmann and Millington.

  • Prior Art Relied Upon: Wydeven427 (Patent 4,410,427), Holzmann (Patent 6,568,540), and Millington (Patent 3,133,847).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination in Ground 1. For claim 38, which depends on claim 34 and adds the limitation that applying the resin comprises "spraying," Petitioner asserted that Millington supplied this teaching. Millington disclosed forming an impervious outer layer on a filter element by spray coating an adhesive, such as a curable acrylic resin. The combination of Wydeven427 and Holzmann provided the base method, while Millington taught the specific application technique of spraying.
    • Motivation to Combine: A POSITA would have been motivated to incorporate Millington’s spraying technique into the method of Wydeven427/Holzmann because spraying was a known, conventional method for applying resin coatings to filters. Millington explicitly taught that its spray coating method reduces cost, increases production speed, and involves less manual operation compared to using fabricated end caps, providing clear advantages a POSITA would seek to achieve.
    • Expectation of Success: The expectation of success was high, as spraying was one of a limited number of known techniques for applying a resin to a surface, and its application to a filter media pack was a straightforward and predictable process.

Ground 4: Obviousness over Gillingham247 and Wydeven247 - Claim 34 is obvious over Gillingham247 in view of Wydeven247.

  • Prior Art Relied Upon: Gillingham247 (Patent 5,792,247) and Wydeven247 (Application # 2002/0096247).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued this combination taught the claimed invention from a different starting point. Gillingham247 was asserted to teach a method of manufacturing an air filter with a fluted media pack and "providing the air filter cartridge with a molded housing seal around the media pack." However, Gillington247 did not teach the application of a curable resin to form a cured-in-place coating circumscribing the pack. Petitioner introduced Wydeven247 to teach this missing element, as it disclosed injecting a sealant or resin into a mold around the filter media to form a protective outer "shell."
    • Motivation to Combine: A POSITA would combine the teachings to add a protective outer coating (from Wydeven247) to the filter design of Gillingham247. It was well known that filter elements required protection during installation and use. The different functions of Gillingham247’s gasket (sealing) and Wydeven247’s coating (protection) would have suggested to a POSITA that they should be fabricated in separate steps, thus meeting another limitation of claim 34.
    • Expectation of Success: A POSITA would have reasonably expected success in applying a known protective coating to a known filter element to enhance its durability, a common and predictable design modification in the field of filter manufacturing.

  • Additional Grounds: Petitioner asserted numerous additional obviousness challenges (Grounds 3, 5-21) based on various combinations of prior art. These grounds largely relied on the same core references (Wydeven427 or Gillingham247) while substituting other patents or applications (e.g., Parmele, Ishii, Krisko) that also taught known techniques such as spraying curable resin or providing molded seals around a filter pack.

4. Key Claim Construction Positions

  • "molded": Petitioner argued this term should be construed as "formed using a mold," and that the patent itself defined it to include both "molded in place" and "separately molded" and then attached. This construction was central to arguments relying on prior art like Holzmann and Gillingham247, which explicitly taught forming seals via molding.
  • "circumscribing": Construed as "around," based on the patent's specification. This was used to map references like Wydeven427, which showed a barrier element extending around the filter media pack's perimeter.
  • "separate": Petitioner argued that when claim 34 required the step of "providing" the housing seal to be "separate from the step of applying" the resin, this was met when the prior art taught different fabrication steps (e.g., molding a seal vs. spraying a coating), which implied distinct, non-simultaneous actions.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 34 and 38 of Patent RE46,700 as unpatentable.