Generac Power Systems Inc v. Champion Power Equipment Inc

1. Case Identification

• Case #: IPR2025-00951
• Patent #: 10,598,101
• Filed: May 16, 2025
• Petitioner(s): Generac Power Systems, Inc., Harbor Freight Tools USA Inc., and MWE Investments, LLC
• Patent Owner(s): Champion Power Equipment, Inc.
• Challenged Claims: 1-19

2. Patent Overview

• Title: Fuel Selector for Dual Fuel Generator
• Brief Description: The ’101 patent discloses a fuel selector for a dual fuel generator that uses a mechanical, sliding "selector switch." This switch physically interlocks two separate fuel valve handles to ensure only one fuel source can be selected at a given time, thereby preventing the mixing of fuels.

3. Grounds for Unpatentability

Ground 1: Obviousness over DuroMax and De Vries - Claims 1-5, 8-16, and 18-19 are obvious over DuroMax in view of De Vries.

• Prior Art Relied Upon: DuroMax (DuroMax XP4400EH Operator’s Manual) and De Vries (Patent 7,481,087).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that DuroMax discloses a conventional dual fuel generator that can run on gasoline or LPG, featuring separate valves for each fuel source. This design mirrors the problem described in the ’101 patent, where nothing prevents a user from opening both valves simultaneously. De Vries taught a safety interlock system for a pair of valves, using a single trapped key that can only unlock one valve at a time, expressly to prevent hazardous situations from incorrect valve sequencing. The combination allegedly provides a valve assembly with two mechanical valves and a selector switch (the key system) that permits manual selection of only one fuel flow at a time, as recited in independent claims 1, 10, and 18.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would combine the known safety interlock of De Vries with the standard dual fuel generator of DuroMax to solve the well-known and dangerous problem of simultaneous fuel flow. The ’101 patent itself identified this as an issue with "typical" prior art generators like DuroMax.
  • Expectation of Success: A POSA would have a high expectation of success, as De Vries taught its interlock system was broadly applicable to industrial appliances controlling liquid or gas flow, and trapped-key interlocks were a mature, widely used technology for improving operational safety.

Ground 2: Obviousness over DuroMax, De Vries, Nakafushi, and Olmr - Claims 1-19 are obvious over DuroMax and De Vries in view of Nakafushi and Olmr.

• Prior Art Relied Upon: DuroMax (DuroMax XP4400EH Operator’s Manual), De Vries (Patent 7,481,087), Nakafushi (JPS61283734A), and Olmr (Patent 5,301,644).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon Ground 1 to address claims reciting a carburetor solenoid switch (e.g., claims 6-7 and 17). Petitioner asserted that a known issue with carbureted dual fuel engines like DuroMax is that residual gasoline in the carburetor float bowl can mix with LPG after switching fuels, causing over-rich conditions, backfires, and poor performance. Nakafushi addressed this exact problem by teaching a control valve downstream of the float bowl, coupled to the fuel selection switch, to cut off residual gasoline flow during LPG operation. Olmr further taught that such a fuel cut-off valve was commonly implemented as a solenoid valve.
  • Motivation to Combine: A POSA would be motivated to add the Nakafushi/Olmr carburetor solenoid solution to the safer DuroMax/De Vries generator to solve the additional known problem of poor engine performance and safety hazards (e.g., backfires) caused by residual fuel when switching between modes. De Vries taught that its key interlock could be coupled to an electric switch, providing a clear path to integrate the solenoid's operation with the primary fuel selection.
  • Expectation of Success: Success would be expected, as this combination involved integrating known solutions to solve distinct, well-understood problems in dual fuel engines.

Ground 3: Anticipation by Fujisawa - Claims 1-4, 9-14, and 18-19 are anticipated by Fujisawa.

• Prior Art Relied Upon: Fujisawa (JP2005330867).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground was argued in the alternative, adopting the Patent Owner's alleged claim construction from related litigation where a single component (a dial) was identified as both the "selector switch" and the "valve handle." Petitioner argued Fujisawa disclosed a dual fuel power generator with a single rotary knob (60) and cam body (59) that directly actuates two fuel valves. This integrated mechanism ensures only one fuel source is active at a time. Under the Patent Owner’s broad interpretation, Fujisawa’s rotary knob/cam assembly (the "selector switch") is also the "valve handle" that actuates the valve assembly, thereby anticipating the limitations of the challenged claims.
  • Key Aspects: This argument directly targeted the Patent Owner’s infringement theory by showing that if the claims are construed that broadly, they are anticipated by a single prior art reference that was not considered during prosecution.

• Additional Grounds: Petitioner asserted additional obviousness challenges over Fujisawa in view of DuroMax (Ground 4) and over Fujisawa and DuroMax in view of Nakafushi and Olmr (Ground 5), relying on similar alternative claim construction arguments and motivations to combine.

4. Key Claim Construction Positions

• "selector switch": Petitioner argued this term was used as a term of art by the patentee and should be construed as "a movable component whose positioning enables subsequent user selection of only one fuel source." This construction distinguishes the claimed mechanical interlock, which merely provides access to a valve handle, from a component that directly selects the fuel flow.
• "valve assembly": Petitioner asserted, based on arguments made during prosecution to overcome a rejection over the Poehlman patent, that this term must be construed as (1) comprising at least one fuel valve and a corresponding, separate valve handle, and (2) being a separate and distinct structure from the "selector switch." This construction was central to distinguishing the ’101 patent from prior art where the switch and valve were integrated.

5. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-19 of Patent 10,598,101 as unpatentable.