PTAB

IPR2025-00805

Harbor Freight Tools USA Inc v. Champion Power Equipment Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Fuel System for a Multi-Fuel Internal Combustion Engine
  • Brief Description: The ’034 patent discloses multi-fuel internal combustion engines and generators operable on both liquid (e.g., gasoline) and gaseous (e.g., LPG) fuels. The patent purports to solve problems associated with switching between fuels, such as overly rich air-fuel ratios, by implementing a switch that powers distinct cutoff solenoids to control the flow of each fuel type.

3. Grounds for Unpatentability

Ground 1: Obviousness over Nakafushi and Olmr - Claims 1-3, 5-9, and 18 are obvious over Nakafushi in view of Olmr.

  • Prior Art Relied Upon: Nakafushi (JPS61283734A) and Olmr (Patent 5,301,644).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Nakafushi, a Japanese patent application, discloses a multi-fuel (gasoline/LPG) engine that meets nearly all limitations of independent claim 1. Nakafushi teaches a carburetor with a float bowl, a gaseous cutoff valve, a liquid fuel cutoff valve (control valve 23) positioned downstream of the float bowl, and a switch to select between fuels. Petitioner contended the only element not explicitly disclosed is that the liquid cutoff valve is a "solenoid." Olmr was cited to cure this, as it expressly teaches a liquid cutoff solenoid valve located in a float bowl to cut off gasoline flow.
    • Motivation to Combine (for §103 grounds): Petitioner asserted that Nakafushi and Olmr address the same problem: controlling gasoline flow from a float bowl in a carburetor. A person of ordinary skill in the art (POSA) would combine them because Olmr provides a specific, well-known component (a solenoid valve) to implement the function of Nakafushi’s more generically described control valve. This would have been a simple and predictable substitution of known components.
    • Expectation of Success (for §103 grounds): A POSA would have had a high expectation of success because solenoid valves were ubiquitous for fuel control applications at the time, and Nakafushi’s existing electrical circuit for its control valve was suitable for operating a solenoid like the one in Olmr.

Ground 2: Obviousness over Nakafushi, Jungmann, and Parlatore - Claims 11-13 and 16-17 are obvious over Nakafushi in view of Jungmann and Parlatore.

  • Prior Art Relied Upon: Nakafushi (JPS61283734A), Jungmann (Application # 2014/0239645), and Parlatore (Application # 2011/0100335A1).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targets claims directed to a "multi-fuel generator and fuel delivery system." Petitioner argued that Nakafushi's multi-fuel engine provides the base system. Jungmann teaches combining such a multi-fuel engine with an alternator to create a generator, fulfilling limitations [11.0] and [11.2]. Parlatore teaches the claimed fuel regulator system, including a primary pressure regulator coupled to a service valve on a pressurized fuel tank and a secondary pressure regulator coupled to the primary one, with the entire system located off-board the generator.
    • Motivation to Combine (for §103 grounds): A POSA would combine Nakafushi’s multi-fuel engine with Jungmann’s generator design to create a more versatile product. A POSA would then incorporate Parlatore’s two-stage, off-board regulator system to improve the safety and reliability of the gaseous fuel delivery, preventing regulator freezing (a known issue with single-stage systems) and allowing for larger, easily swappable off-board fuel tanks.
    • Expectation of Success (for §103 grounds): Success was expected as the combination involves integrating known systems for their intended purposes—a multi-fuel engine in a generator application and an improved, known type of fuel regulation system—without changing their fundamental principles of operation.

Ground 3: Anticipation by the Kubota Workshop Manual - Claims 1-3, 5-9, 11-14, 17-20, and 22-23 are anticipated by the Kubota DF972 Workshop Manual.

  • Prior Art Relied Upon: Workshop Manual (Kubota DF972-E2 Workshop Manual).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that the Workshop Manual, a publicly available document describing the Kubota DF972-E2 engine, anticipates the challenged claims under 35 U.S.C. §102. The manual allegedly discloses every element, including a multi-fuel (gasoline/LPG) engine with an alternator (generator), a carburetor with a float chamber, a "Gasoline Cut Off Solenoid" positioned downstream of the float chamber, an "LPG Cut Off Solenoid," and a "Fuel Select Switch" for selectively coupling power to the solenoids. The manual also describes a two-stage vaporizer with "Primary" and "Secondary" chambers that function as the claimed pressure regulators. The petition further noted that an accompanying Operator’s Manual confirms the engine allows for "on-the-fly" switching between fuels while running.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds combining Nakafushi with Olmr and Duffy (for fuel overlap timing) and with Bernhardsson (for normally-closed solenoid designs). Further grounds relied on the Workshop Manual in combination with Duffy, Parlatore, and a "Tri-Fuel Video" to challenge claims requiring specific fuel overlap timing or off-board regulator configurations.

4. Relief Requested

  • Petitioner requests institution of IPR for claims 1-24 and cancellation of all challenged claims as unpatentable.