PTAB

IPR2017-00427

General Electric Co v. United Technologies Corp

Log In
Key Events
Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Turbofan Engine Control System and Method for Managing a Turbofan Operating Line
  • Brief Description: The ’280 patent relates to a control system for a turbofan aircraft engine. The invention describes a controller that detects an "undesired stability margin" for the engine's fan and, in response, changes the exit area of the bypass flow path nozzle to lower the fan's operating line and increase its stability margin, thereby preventing stall or surge.

3. Grounds for Unpatentability

Ground 1: Obviousness over Harner - Claims 1, 8-10, 12-13, and 15-16 are obvious over Harner in view of the knowledge of one of ordinary skill in the art.

  • Prior Art Relied Upon: Harner (Patent 3,932,058).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Harner taught a complete turbofan engine control system with all the structural elements of claim 1. Harner’s controller was programmed to prevent fan surge by selecting the larger of two computed nozzle areas: a "normal" area for optimal performance and a "minimum" area required to avoid surge. Petitioner asserted that the condition where the minimum required area is larger than the normal area corresponds to the claimed "undesired stability margin." By selecting this larger area, Harner’s controller was argued to inherently increase the nozzle exit area in response to detecting this condition. The claimed effects of lowering the turbofan operating line and increasing the stability margin were presented as the well-known and obvious results of increasing the nozzle exit area, which would have been understood by a person of ordinary skill in the art (POSA).
    • Motivation to Combine (for §103 grounds): This ground relied on a single reference combined with the general knowledge of a POSA. The motivation was to apply fundamental, well-understood principles of turbofan engine operation to the system explicitly disclosed in Harner.
    • Expectation of Success (for §103 grounds): A POSA would have a high expectation of success in recognizing that Harner’s surge avoidance system would necessarily lower the fan operating line, a predictable outcome of increasing nozzle area.

Ground 2: Obviousness over Harner and Rey - Claim 11 is obvious over Harner in view of Rey.

  • Prior Art Relied Upon: Harner (Patent 3,932,058) and Rey (Patent 6,318,070).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon Ground 1, asserting that Harner taught the control system of claim 10. To meet the limitations of dependent claim 11, Petitioner cited Rey. Rey was alleged to disclose a specific, well-known mechanical implementation for a variable area nozzle: a "flow control device" comprising a plurality of flaps arranged around the perimeter of the bypass flow path. These flaps open to increase the physical nozzle exit area.
    • Motivation to Combine (for §103 grounds): A POSA would combine Harner’s control logic with Rey’s mechanical structure because Rey’s flap-based design represented a known, suitable, and common method for implementing the variable area nozzle required by Harner’s system. Both references addressed the shared problem of improving fan stability, making the combination logical for achieving a more robust design.
    • Expectation of Success (for §103 grounds): A POSA would expect success in integrating Rey’s established flap mechanism into Harner’s control system, as it was a straightforward application of a known component to perform its intended function.

Ground 3: Obviousness over Gisslen and Harloff - Claims 1-4 and 7 are obvious over Gisslen in view of Harloff.

  • Prior Art Relied Upon: Gisslen (Patent 3,892,358) and Harloff (Patent 4,130,872).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Gisslen disclosed the basic structural configuration of a turbofan engine, including a core nacelle, fan nacelle, and a variable area exhaust nozzle comprised of an annular array of flaps. Gisslen did not, however, detail the control system. Harloff was alleged to supply the missing control logic, disclosing a system that uses pressure sensors (probes) at the fan’s inlet and outlet to calculate a pressure ratio. This ratio is used to detect an undesired stability margin (incipient surge). When this condition is detected, Harloff’s controller changes the nozzle area to move the fan’s operating point away from the surge line, thereby lowering the operating line and increasing the stability margin.
    • Motivation to Combine (for §103 grounds): A POSA would be motivated to combine Gisslen’s engine structure with Harloff’s control strategy to achieve the well-known benefit of enhancing engine performance and ensuring adequate stall margin during various flight conditions. The combination represented the integration of a known control system with a known, compatible engine structure to solve a known problem.
    • Expectation of Success (for §103 grounds): A POSA would have a reasonable expectation of success, as the combination involved applying a known control method (Harloff) to a standard engine configuration with a variable nozzle (Gisslen) to achieve the predictable result of improved stability.

4. Key Claim Construction Positions

  • "undesired stability margin": Petitioner argued this term should be understood to mean that the fan section has insufficient stability margin to avoid an instability, such as a stall or surge. This construction was crucial for mapping prior art references that explicitly taught "surge avoidance" or preventing "incipient surge" onto the claim language.
  • "flow control device": Petitioner proposed this term should mean any structure or device that either physically or effectively changes the nozzle exit area of the bypass flow path. This broad construction allowed Petitioner to assert that the variable area nozzles with flaps described in references like Rey and Gisslen met the claim limitation.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 7-13, and 15-16 of Patent 8,313,280 as unpatentable.