PTAB

IPR2025-01099

Generac Power Systems Inc v. Champion Power Equipment Inc

Key Events

Petition

petition

Title: Fuel Selector for Dual Fuel Generator
Brief Description: The ’667 patent discloses a fuel selector for a dual fuel generator that includes a sliding "selector switch." The switch is designed to physically interlock with the valve handles of two separate fuel sources (e.g., LPG and gasoline) to prevent both fuel valves from being open at the same time, thereby avoiding a potentially unsafe fuel mixing condition.

"Selector Switch": Petitioner argued that based on the patent’s specification and prosecution history, this term should be construed as "a movable component whose positioning enables subsequent user selection of only one fuel source." This construction distinguishes the switch, which merely allows access, from the valve handle that actually performs the fuel selection. Petitioner contended this is a special definition inconsistent with the ordinary meaning of an electrical switch.
"Valve Assembly": Petitioner argued that the prosecution history of the parent ’101 patent establishes that the "valve assembly" must (1) comprise at least one fuel valve and a corresponding valve handle for manual operation, and (2) be a separate and distinct structure from the "selector switch."
Patent Owner's Apparent Construction: Petitioner noted that in related litigation, the Patent Owner has advanced a broader construction where a single dial can be both the "selector switch" and the "valve handle" component of the "valve assembly." Petitioner’s anticipation and obviousness grounds involving Fujisawa are argued in the alternative under this broader construction.

Prior Art Relied Upon: DuroMax (Duro Max XP4400EH Operator’s Manual) and De Vries (Patent 7,481,087).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted that DuroMax discloses a conventional dual fuel generator that can run on gasoline or LPG. The DuroMax manual explicitly warns the user to shut one fuel source off before using the other, acknowledging the unsafe condition the ’667 patent purports to solve but providing no mechanical prevention. De Vries discloses a "safety interlock system" for industrial valve assemblies, using a trapped-key mechanism to ensure only one of two valves can be opened at a time. The combination of DuroMax's generator with De Vries's interlock system renders the claims obvious.
- Motivation to Combine: A POSITA would combine the teachings to improve the safety of the DuroMax generator. The known hazard of simultaneously open fuel lines, explicitly warned against in DuroMax, would motivate a POSITA to implement a well-known safety solution like the trapped-key interlock taught by De Vries to prevent user error.
- Expectation of Success: A POSITA would have a high expectation of success, as De Vries teaches its interlock system is suitable for controlling the flow of liquid or gaseous fluids in industrial appliances, which is precisely the application in the DuroMax generator.

Prior Art Relied Upon: DuroMax, De Vries, Nakafushi (JPS61283734A), and Olmr (Patent 5,301,644).
Core Argument for this Ground:
- Prior Art Mapping: This ground builds on Ground 1 to address claims reciting a carburetor solenoid (claims 6-8 and 10-18). Petitioner argued that DuroMax suffers from a known issue where residual gasoline in the carburetor causes unsteady performance when switching to LPG. Nakafushi explicitly addresses this same problem by teaching a control valve that shuts off gasoline flow from the carburetor when LPG is selected. Olmr provides a specific, well-known implementation of such a valve as a solenoid valve, which it teaches can be used for cutting off fuel supply.
- Motivation to Combine: A POSITA would be motivated to incorporate the teachings of Nakafushi and Olmr into the DuroMax/De Vries combination to solve the known problem of poor performance caused by residual fuel mixing. Coupling the solenoid operation to the fuel selector switch is a logical step to automate the process and further improve safety and performance.
- Expectation of Success: A POSITA would expect success because Nakafushi addresses the exact problem that occurs in dual fuel engines like DuroMax. Implementing this solution with a standard solenoid valve as taught by Olmr would be a straightforward application of known engineering principles.

Prior Art Relied Upon: Fujisawa (JP2005330867).
Core Argument for this Ground:
- Prior Art Mapping: This ground was argued in the alternative, assuming the Patent Owner’s broader construction where a single rotary knob can be both the "selector switch" and part of the "valve assembly." Petitioner asserted that Fujisawa discloses a fuel switching device for a dual fuel generator. Its rotary knob (60) and cam body (59) function as a single unit to actuate two separate valve bodies (55a, 55b), ensuring only one fuel source is supplied at a time. Under the Patent Owner's broad construction, this single rotary knob structure in Fujisawa meets all limitations of the claims for a "selector switch" positioned on a "valve assembly" to manually select a fuel flow.
Additional Grounds: Petitioner asserted additional obviousness challenges under the Patent Owner's apparent construction, arguing claims 1-5 and 9 are obvious over Fujisawa in view of DuroMax, and claims 1-18 are obvious over Fujisawa and DuroMax in view of Nakafushi and Olmr.

Petitioner requests institution of an inter partes review and cancellation of claims 1-18 of the ’667 patent as unpatentable.