PTAB

IPR2025-01271

Harbor Freight Tools USA Inc v. Champion Power Equipment Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Batteryless Dual Fuel Engine with Liquid Fuel Cut-Off
  • Brief Description: The ’398 patent relates to dual-fuel engines for generators operable on both liquid (e.g., gasoline) and gaseous (e.g., LPG) fuels. The invention purports to solve problems of unstable operation during fuel switching by incorporating a liquid fuel cut-off into the carburetor, which is actuated by a switch to interrupt liquid fuel flow when operating on gaseous fuel.

3. Grounds for Unpatentability

Ground 1: Anticipation by the Workshop Manual - Claims 1, 3, 22, and 57 are anticipated under 35 U.S.C. §102 by the Workshop Manual.

  • Prior Art Relied Upon: Workshop Manual (Kubota DF972-E2 Workshop Manual).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued the Workshop Manual, which describes the Kubota DF972 dual-fuel engine, disclosed every element of independent claims 1 and 57. The manual detailed an engine operable on gasoline (liquid fuel) and LPG (gaseous fuel), a fuel-select switch to change operation, a carburetor attached to the engine intake, and separate liquid and gaseous fuel valves. Crucially, Petitioner asserted that the manual’s “Gasoline Cut Off Solenoid” is a liquid fuel cut-off incorporated into the carburetor that interrupts gasoline flow upon actuation of the switch from the gasoline to the LPG position.
    • Key Aspects: This ground asserted that a single, publicly available service manual for a commercial engine contained all features of the core invention claimed in the ’398 patent.

Ground 2: Obviousness over Workshop Manual Combination - Claims 2, 4-14, 19-21, 23, 32-42, and 58 are obvious over the Workshop Manual in view of Matsushima, Yamamoto, and Olmr.

  • Prior Art Relied Upon: Workshop Manual (Kubota DF972-E2 Workshop Manual), Matsushima (Patent 5,161,496), Yamamoto (Patent 7,549,403), and Olmr (Patent 5,301,644).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the Workshop Manual's disclosure of a base dual-fuel engine. Petitioner argued that the addition of features in the dependent claims was obvious. Matsushima taught a batteryless engine with a manual recoil starter and an electrical generator. Yamamoto taught enclosing such a generator in a protective housing. Olmr taught a normally-open fuel cut-off solenoid, in contrast to the normally-closed solenoid in the Workshop Manual.
    • Motivation to Combine: A person of ordinary skill in the art (POSA) would combine the Workshop Manual's engine with Matsushima's recoil starter to create a batteryless configuration, a common design choice to improve reliability and reduce cost. A POSA would enclose the resulting generator in a housing as taught by Yamamoto for standard protection and safety. A POSA would have been motivated to substitute Olmr's normally-open solenoid for the Workshop Manual's normally-closed version to enable engine starting on liquid fuel even if the battery were dead, a key benefit for portable generators.
    • Expectation of Success: A POSA would have a reasonable expectation of success because incorporating recoil starters, housings, and alternative solenoid types were routine, well-understood modifications for small engines involving simple mechanical adaptation and basic rewiring.

Ground 3: Anticipation by Nakafushi - Claims 1, 3, 22, and 57 are anticipated under §102 by Nakafushi.

  • Prior Art Relied Upon: Nakafushi (JPS61283734A).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Nakafushi, which disclosed a gasoline/LPG combined engine, anticipated all elements of the independent claims. Nakafushi described a dual-fuel engine, a fuel switching switch, a carburetor attached to the engine intake, a liquid fuel valve ("gasoline cut valve 17"), and a gaseous fuel valve ("LPG cut valve 18"). Petitioner contended that Nakafushi’s "control valve 23" is a liquid fuel cut-off that is incorporated into the carburetor and actuates upon switching from liquid to gaseous fuel to interrupt gasoline flow, thereby meeting the final limitation of claim 1.
    • Key Aspects: This ground presented an alternative anticipation argument based on a Japanese patent publication, arguing it solved the same problem of fuel mixture control during switching with the same claimed structure.

  • Additional Grounds: Petitioner asserted numerous additional anticipation and obviousness challenges. These included anticipation of various claims over Holzapfel (Patent 1,931,698), Neal (Patent 4,776,988), and Winberg (Patent 6,213,083). Further obviousness grounds were based on combinations of Nakafushi with Matsushima, Yamamoto, and Olmr, as well as combinations of Holzapfel with Winberg/Neal and Yamamoto.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-17, 19-26, 32-46, 53-54, and 56-58 of the ’398 patent as unpatentable.