PTAB

IPR2025-01089

Nissan Motor Co Ltd v. Longhorn Automotive Group LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Directly Injecting Internal Combustion Engine
  • Brief Description: The ’238 patent relates to a specific piston geometry for direct-injection internal combustion engines. The design centers on a piston recess with a central elevation and a specifically shaped surface intended to manage fuel distribution for both early and late injection timings to improve combustion efficiency and reduce emissions.

3. Grounds for Unpatentability

Ground 1: Claims 1-3, 5, and 6 are anticipated by, or minimally obvious over, Ishida.

  • Prior Art Relied Upon: Ishida (Japanese Utility Model Application Publication No. S58-102720).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Ishida, which was not considered during prosecution, discloses a direct-injection diesel engine that meets every limitation of the challenged claims. Specifically, Petitioner contended Ishida’s piston features a combustion chamber (the claimed "piston recess") with a central raised "hump" (the "elevation") and an outwardly sloped side wall that is "substantially planar" with an "ascending gradient." Petitioner asserted that Ishida’s fundamental design principle—directing injected fuel to impact and "rebound" from this side wall—inherently satisfies the functional limitations of distributing the fuel spray for both "early as possible" and "late as possible" injections.
    • Key Aspects: Petitioner argued that the features used to overcome prior art during prosecution—namely the substantially planar surface with an ascending gradient—were explicitly disclosed in Ishida.

Ground 2: Claims 7 and 8 are obvious over Ishida in view of Oota.

  • Prior Art Relied Upon: Ishida, and Oota (Japanese Patent Application Publication No. S54-74012).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims requiring the surface connected to the recess edge to form an "obtuse angle" with the piston's upper surface. Petitioner argued that Ishida discloses a piston with a peripheral "lip" feature, whereas Oota teaches a similar, but simpler, known lipless piston design. Petitioner asserted that modifying Ishida by removing its lip, as suggested by Oota's simpler design, would result in a piston where the outwardly sloped side wall directly meets the flat top surface of the piston, necessarily forming an obtuse angle as claimed.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Ishida’s design with Oota’s known lipless configuration as a straightforward design choice. The motivation was to simplify manufacturing, reduce cost, and improve durability by eliminating Ishida’s thin lip, which Petitioner argued a POSITA would recognize as prone to cracking under high temperatures and stresses.
    • Expectation of Success: A POSITA would have had a high expectation of success, as removing a feature to arrive at another well-known and simpler piston configuration was a predictable design modification.

Ground 3: Claims 9-13 are obvious over Ishida in view of Gatellier.

  • Prior Art Relied Upon: Ishida, and Gatellier (Application # 2002/0117146).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground targeted claim 9, which requires an injection nozzle angle between 50° and 120°. While Ishida illustrates an injector, it does not explicitly state the injection angle. Petitioner argued that Gatellier expressly teaches that an injection angle "advantageously selected between 0° and 120°" and "preferably selected between 40° and 100°" enhances engine performance and flexibility. The claimed range falls squarely within Gatellier's teaching.
    • Motivation to Combine: A POSITA seeking to enhance the performance and operational flexibility of an engine like Ishida's would have been motivated to apply Gatellier's specific teachings on advantageous injection angles. This modification would address known issues with injection timing and cylinder wall wetting, which Gatellier was designed to solve.
    • Expectation of Success: Incorporating an injector with a known, advantageous nappe angle into an existing piston bowl design was a standard engineering approach. A POSITA would expect this combination to yield the desired improvements in injection flexibility without compromising Ishida's fundamental fuel-wall impingement mechanism.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations including Iijima (Patent 6,314,933) for teaching the rounding of recess edges to improve durability, Takatomo (Japanese Patent Application Publication No. 2697100) as both a primary reference and as evidence for combinations, and various three-way combinations of these references.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under Fintiv by stipulating that, if the IPR is instituted, it will not pursue in district court any invalidity ground that was raised or could have been reasonably raised in the petition.

5. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-14 of the ’238 patent as unpatentable.