PTAB

IPR2018-00018

STIHL Incorporated v. Electrojet Technologies, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Electronic Engine Control With Reduced Sensor Set
  • Brief Description: The ’081 patent discloses an electronic control system for a fuel-injected engine that determines engine operating parameters, including engine position and intake air mass, using signals from a single intake pressure sensor. This system aims to reduce the number of required sensors, such as dedicated crankshaft position sensors.

3. Grounds for Unpatentability

Ground 1: Claims 1-12, 14-16, and 18 are obvious over Abe in view of Kupske.

  • Prior Art Relied Upon: Abe (Patent 4,866,620) and Kupske (German Patent No. DE 10116485).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Abe disclosed an engine control apparatus (ECU) that determines intake air mass from a single intake pressure sensor. However, Abe did not explicitly teach determining engine crankshaft position from that same sensor. Kupske allegedly remedied this deficiency by teaching a system that uses an intake pressure sensor to determine engine cycle time, speed, and crankshaft position. Kupske explicitly disclosed that its pressure sensor could serve as a backup to, or replacement for, traditional crankshaft and camshaft sensors, arithmetically emulating their signals based on the intake manifold pressure signal.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have been motivated to combine the teachings of Abe and Kupske. Both references address engine control systems for fuel-injected engines and seek to simplify sensor complexity. A POSITA would combine Kupske’s method of determining engine position from a pressure sensor with Abe’s system to create a more robust and less complex apparatus, yielding predictable results such as improved redundancy and cost savings.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in combining the references. Petitioner contended that the references’ teachings were consistent, as both used an intake pressure sensor to derive key engine parameters. The combination represented the application of a known technique (Kupske's position sensing) to a known system (Abe's air mass calculation) to achieve a predictable improvement.

Ground 2: Claims 1, 3, 5, 6, 8, 10-12, and 14 are obvious over Ostdiek in view of Vernier.

  • Prior Art Relied Upon: Ostdiek (Patent 5,092,301) and Vernier (Patent 5,261,369).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Ostdiek disclosed a simple fuel control system for a small engine that used a single pressure sensor to determine engine fuel requirements. Ostdiek taught measuring the time between pressure waveform pulses to determine engine speed and using pressure values to determine the quantity of inhaled air. Petitioner argued that to the extent Ostdiek did not explicitly teach determining the specific angular position of the crankshaft, Vernier supplied this element. Vernier taught analyzing a continuous intake pressure signal to identify inflection points and maxima that correspond to specific, known engine events like valve opening and the piston reaching top-dead-center, thereby allowing for precise determination of crankshaft position.
    • Motivation to Combine: A POSITA would have been motivated to incorporate Vernier's more precise engine position detection method into Ostdiek’s system. Both references are in the same field and describe using an intake pressure sensor to determine multiple engine parameters for simplicity and cost reduction. A POSITA would have sought to enhance the control capabilities of Ostdiek’s system by integrating Vernier’s technique for more accurate crankshaft position tracking.
    • Expectation of Success: Success was predictable because both Ostdiek and Vernier disclosed similar methods for determining engine speed from pressure sensor data and touted the advantages of using a single sensor. A POSITA would have recognized the teachings as compatible and pursued the combination of these known solutions with a reasonable expectation of success.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, adding POSITA knowledge to the Abe/Kupske combination to teach a "crank trigger" (claims 13, 17) and to the Ostdiek/Vernier combination to teach detecting engine load and a "crank trigger" (claims 2, 4, 7, 9, 13, 15-18). These arguments relied on the premise that such features were well-known elements in the art that a POSITA would have been motivated to add to the primary combinations to achieve predictable results.

4. Key Claim Construction Positions

  • Petitioner argued that multiple claim terms reciting "means" followed by functional language should be construed under pre-AIA 35 U.S.C. §112, 6th paragraph, as they lacked sufficient recited structure. This was central to the invalidity arguments, as the proposed constructions identified specific structures in the specification that were allegedly disclosed in the prior art.
    • “pressure sensor means for developing periodic sensor voltage timing pulses…” (Claim 1(b)): Petitioner proposed this term should be construed as an intake pressure sensor in combination with an ECU that processes the sensor signal.
    • “pressure sensor means for measuring intake air mass…” (Claim 1(c)): Petitioner argued this term should also be construed as an intake pressure sensor in combination with an ECU.
    • “redundant means to determine crankshaft position…” (Claim 5): Petitioner asserted this term should be construed as an intake pressure sensor in combination with an ECU, where the ECU determines crankshaft position from the pressure signal in the event of a failure of another sensor (e.g., a primary crankshaft position sensor).

5. Relief Requested

  • Petitioner requested that the Board institute an inter partes review and cancel claims 1-18 of the ’081 patent as unpatentable.