PTAB

IPR2025-01457

Harbor Freight Tools USA Inc v. Champion Power Equipment Inc

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Batteryless Dual Fuel Engine with Liquid Fuel Cut-Off
  • Brief Description: The ’145 patent discloses dual-fuel generators operable on a liquid fuel (e.g., gasoline) and a gaseous fuel (e.g., LPG). The invention purports to solve problems of unstable operation during fuel switching by using a switch that powers cutoff solenoids to control liquid and gaseous fuel flow.

3. Grounds for Unpatentability

Ground 1: Obviousness over Workshop Manual - Claims 1-5 and 10 are obvious over the Kubota DF-972-E2 Workshop Manual.

  • Prior Art Relied Upon: Kubota DF-972-E2 Workshop Manual (“Workshop Manual”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the Workshop Manual, which describes the Kubota DF-972 dual-fuel engine, taught all limitations of independent claim 1. Specifically, it disclosed a dual-fuel (gasoline/LPG) engine [1.1] used with an alternator (an electrical power generator) comprising a charging coil [1.2]. It further disclosed a “Fuel Select Switch” to change operation between fuels [1.3], a carburetor connected to both fuel sources [1.4], a "Gasoline Cut Off Solenoid" to interrupt liquid fuel flow upon actuation of the switch [1.5], and a voltage regulator coupled to the alternator to provide regulated voltage to the solenoid [1.6]. Implementing this engine in a generator was argued to be obvious. Dependent claims were allegedly met by disclosures of specific fuel valves (claim 2), mechanical valves (claim 3), solenoid attachment to the carburetor (claim 4), and the use of LPG/gasoline (claim 5).
    • Motivation to Combine (for §103 grounds): This ground relies on a single reference, but Petitioner argued it would have been obvious for a person of ordinary skill in the art (POSITA) to implement the Workshop Manual’s engine in a generator, as dual-fuel generators were well-known.
    • Expectation of Success (for §103 grounds): A POSITA would have had an expectation of success due to the known compatibility of such engines with generator applications.

Ground 2: Obviousness over Nakafushi, Matsushima, and Olmr - Claims 1-10 are obvious over Nakafushi in view of Matsushima and Olmr.

  • Prior Art Relied Upon: Nakafushi (JPS61283734A), Matsushima (Patent 5,161,496), and Olmr (Patent 5,301,644).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Nakafushi disclosed the core dual-fuel engine system of claim 1, including an engine operable on gasoline and LPG, a carburetor, and a “fuel switching switch” that actuates valves to interrupt liquid fuel flow. To the extent Nakafushi’s valves were not explicitly solenoids, Petitioner argued Olmr taught using a solenoid for the identical function of cutting off gasoline flow from a float bowl. For the electrical power generator with a charging coil and voltage regulator limitations, Petitioner pointed to Matsushima, which disclosed a batteryless engine with an AC generator (alternator) and a power supply circuit that rectifies and stabilizes the output voltage.
    • Motivation to Combine (for §103 grounds): A POSITA would combine Nakafushi and Olmr because both relate to gasoline engines and address the same problem of cutting off fuel flow from the float bowl; Olmr merely provided an express example (a solenoid) for the function taught by Nakafushi. A POSITA would combine this engine with Matsushima’s generator system to provide a reliable, regulated power source for the engine's electrical components, such as the fuel cut-off solenoid.
    • Expectation of Success (for §103 grounds): Success was expected because using solenoids to control fuel flow and using alternators with voltage regulators in small engines were common, well-understood practices.

Ground 3: Obviousness over Workshop Manual, Matsushima, and Winberg - Claims 11-16 are obvious over Workshop Manual in view of Matsushima and Winberg.

  • Prior Art Relied Upon: Workshop Manual, Matsushima (Patent 5,161,496), and Winberg (Patent 6,213,083).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground targets independent claim 11, which recites a dual-fuel generator with a “manually actuated fuel shutoff” having an internal end to block fuel flow and an external end for actuation. Petitioner argued Workshop Manual provided the basic dual-fuel engine and carburetor, while Winberg disclosed the specific manually actuated fuel shutoff. Winberg taught a plunger inside the carburetor (first end) actuated by an external lever assembly (second end) to block a fuel passage. For dependent claims, Matsushima was cited for its disclosure of a pull-start, batteryless engine (claim 12). Winberg was further cited for its disclosure of a rotating mechanical valve (claim 14) and a carburetor with a float bowl, throat, and specific fuel passage configuration (claim 15).
    • Motivation to Combine (for §103 grounds): A POSITA would combine Workshop Manual and Winberg because both relate to fuel shutoff systems in carburetors for small engines. A POSITA would be motivated to incorporate Winberg's manual shutoff, a known and reliable design, into the Workshop Manual's dual-fuel system. The motivation to add Matsushima’s pull-start, batteryless design was to improve reliability and reduce the cost and weight of the generator.
    • Expectation of Success (for §103 grounds): Success was expected because the float bowl and fuel nozzle configurations in Winberg and Workshop Manual were substantially similar, making substitution of the fuel shutoff mechanism straightforward.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds based on Holzapfel (Patent 1,931,698) as a primary reference for a dual-fuel engine with mechanical fuel selection, combined with Matsushima, Olmr, and/or Winberg to add features like a batteryless generator and specific solenoid or manual shutoff designs.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-16 of the ’145 patent as unpatentable.