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IPR2017-00428

General Electric Co v. United Technologies Corp

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Geared Turbofan Gas Turbine Engine
  • Brief Description: The ’920 patent relates to a geared turbofan engine architecture for aircraft. The claims combine specific structural features, such as a gear train and multi-stage turbine sections, with a set of functional operating parameters, including a high bypass ratio, a low fan pressure ratio, and a low fan tip speed.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over Kurzke - Claims 1, 2, 7, and 8 are anticipated by or obvious over Kurzke.

  • Prior Art Relied Upon: Kurzke (Joachim Kurzke, Fundamental Differences Between Conventional and Geared Turbofans, ASME Turbo Expo 2009).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kurzke, a study on optimizing turbofan engines, discloses a geared turbofan design that meets every limitation of claims 1, 2, 7, and 8. Specifically, Kurzke's disclosed "bypass ratio 14" engine includes a gear train, a three-stage low-pressure turbine (LPT) (the "first turbine section"), a two-stage high-pressure turbine (HPT) (the "second turbine section"), and a bypass ratio of 14, which is greater than the claimed "about six (6)". Kurzke's data tables further disclose a gear ratio of 3.0 (meeting claim 7's "> 2.5") and an LPT pressure ratio of 6.2 (meeting claim 8's "> 5.0").
    • Motivation to Combine (for §103 grounds): For the obviousness argument, Petitioner contended that while Kurzke's diagrams do not explicitly show a full fan nacelle, the reference describes an engine for aircraft use. A POSITA would find it obvious to incorporate a conventional fan nacelle mounted about the core nacelle to define a bypass flow path, as this is a standard and necessary component for any ducted turbofan engine in commercial aviation.
    • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success in implementing a standard nacelle on the Kurzke engine, as it is a routine and well-understood integration.

Ground 2: Obviousness over Daly - Claims 1 and 19 are obvious over Daly.

  • Prior Art Relied Upon: Daly (Mark Daly, Pratt & Whitney PW1000G, Jane's Aero-Engines, Mar. 2010).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Daly describes the commercial PW1000G engine, which embodies the features of claim 1. Daly discloses a two-shaft geared turbofan with a three-stage LP turbine, a two-stage HP turbine, a 3:1 reduction gearbox, and a bypass ratio between 10:1 and 13:1. For claim 19, Petitioner calculated that Daly's disclosed parameters (73-inch fan diameter, ~9,000 rpm LPT speed at take-off, 3:1 gear ratio) result in an actual fan tip speed of ~955 ft/sec. This corresponds to a "low corrected fan tip speed" of less than 1150 ft/sec for all realistic ambient temperatures.
    • Motivation to Combine (for §103 grounds): Similar to the Kurzke ground, Petitioner argued that adding a fan nacelle to define a bypass flow path is a conventional and obvious step for an engine like the PW1000G, which is intended for commercial airliners.
    • Expectation of Success (for §103 grounds): The integration of a nacelle onto the PW1000G engine core is a standard design choice with predictable results.

Ground 3: Obviousness over Wendus and Moxon - Claims 1, 4, 9-14, 17, and 19 are obvious over Wendus in view of Moxon.

  • Prior Art Relied Upon: Wendus (Bruce E. Wendus et al., Follow-On Technology Requirement Study for Advanced Subsonic Transport, Aug. 2003) and Moxon (Julian Moxon, How to save fuel in tomorrow's engines, FLIGHT International, Jul. 1983).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Wendus discloses a geared "Advanced Ducted Propulsor" (ADP) engine that meets nearly all limitations of the challenged claims, including a six-stage LPT (meeting claims 1 and 4), a 4.2:1 gearbox (meeting claim 12), a bypass ratio of 16.7, and a fan pressure ratio and corrected tip speed within the claimed ranges. However, Wendus discloses a one-stage HPT, whereas the claims require at least a two-stage HPT. Moxon was introduced to supply this missing element, as it explicitly discloses and discusses the design of two-stage HPTs for high-efficiency turbofan engines.
    • Motivation to Combine (for §103 grounds): A POSITA would combine Wendus and Moxon because Wendus acknowledges that its high-work, single-stage HPT design results in "substantial mechanical and structural challenges." Moxon directly addresses this known problem, teaching that using a two-stage HPT design (instead of a single-stage one) alleviates mechanical stress and improves reliability. This provided a clear motivation to modify the Wendus engine with the two-stage HPT taught by Moxon to solve the very problem identified in Wendus.
    • Expectation of Success (for §103 grounds): A POSITA would expect this combination to succeed, as it involved replacing one component (a one-stage HPT) with a known, viable alternative (a two-stage HPT) to achieve the predictable benefit of reduced mechanical stress.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge based on Knip (a 1987 NASA technical memorandum) for claims 1 and 3.

4. Key Claim Construction Positions

  • "bypass ratio ... greater than about six (6)": Petitioner argued this limitation should not be confined to a specific operating condition (e.g., cruise). Because the claim language is silent on conditions, the limitation is met if the engine achieves the specified bypass ratio at any point during operation (e.g., takeoff, climb, or cruise), a position Petitioner noted Patent Owner had taken during prosecution of a related application.
  • "fan pressure ratio across the [plurality of] fan blades is less than 1.45": Petitioner contended that, based on the patent's own definition of "low fan pressure ratio," this phrase must be interpreted atypically to mean the pressure ratio across the fan blades alone, excluding the pressure drop typically caused by downstream Fan Exit Guide Vanes (FEGVs). This construction is critical for comparing the claimed value to prior art, as a conventional "fan pressure ratio" measurement would include the FEGV loss and thus be lower.

7. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-4, 7-14, 17, and 19 as unpatentable.