PTAB
IPR2025-00805
Harbor Freight Tools USA, Inc. v. Champion Power Equipment, Inc.
1. Case Identification
- Case Number: IPR2025-00805
- Patent #: 10,393,034
- Filed: April 29, 2025
- Petitioner(s): Harbor Freight Tools USA Inc., Generac Power Systems, Inc., and MWE Investments, LLC
- Patent Owner(s): Champion Power Equipment Inc.
- Challenged Claims: 1-24
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 of unstable operation during fuel switching by using a switch to control separate liquid and gaseous fuel cutoff solenoids, with the liquid cutoff solenoid located downstream of the carburetor's float bowl.
3. Grounds for Unpatentability
Ground 1: Claims 1-3, 5-9, and 18 are obvious over Nakafushi in view of Olmr.
- Prior Art Relied Upon: JPS61283734A (“Nakafushi”), Patent 5,301,644 (“Olmr”).
- Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Nakafushi, a Japanese patent application, discloses the core elements of a multi-fuel (gasoline/LPG) engine with a carburetor, a float bowl, and separate cutoff valves for each fuel type. Crucially, Nakafushi taught placing a "control valve" (23) downstream of the float chamber to prevent residual gasoline from creating an over-rich mixture when switching to LPG, addressing the same problem as the ’034 patent. While Nakafushi did not explicitly label its valves as solenoids, Petitioner contended that Olmr taught the missing element: an express disclosure of using a solenoid valve to cut off fuel flow from a carburetor's float bowl to the engine.
- Motivation to Combine: A POSITA would combine these references as a simple substitution to implement a well-known component. Nakafushi provided the system architecture and identified the need for a cutoff valve downstream of the float bowl, while Olmr provided an express example of such a valve—a solenoid—used for the identical purpose of cutting gasoline flow from the float bowl.
- Expectation of Success: A POSITA would have a high expectation of success because using solenoid valves for fuel control was ubiquitous at the time of the invention. The electrical circuits disclosed in both Nakafushi and Olmr for controlling their respective valves were functionally identical, making the integration of Olmr's solenoid into Nakafushi's system straightforward and predictable.
Ground 2: Claims 11-13 and 16-17 are obvious over Nakafushi in view of Jungmann and Parlatore.
- Prior Art Relied Upon: Nakafushi, Application # 2014/0239645 (“Jungmann”), Application # 2011/0100335A1 (“Parlatore”).
- Core Argument for this Ground:
- Prior Art Mapping: This ground targets the generator-specific claims. Petitioner asserted that the combination of Nakafushi (providing the base multi-fuel engine), Jungmann (teaching the use of a multi-fuel engine with an alternator to create a generator), and Parlatore (disclosing a dual-stage pressure regulator for gaseous fuel) renders the claims obvious. Parlatore specifically taught a system with a primary regulator at the fuel tank and a secondary regulator to further reduce pressure before delivery to the engine, meeting the limitations for the claimed "fuel regulator system."
- Motivation to Combine: A POSITA would combine Nakafushi's engine with Jungmann's alternator to create a versatile generator, a common and desirable product. A POSITA would then incorporate Parlatore's dual-stage regulator system into the gaseous fuel line to solve the known problem of single-stage regulators freezing during operation and to achieve more precise fuel delivery, thereby improving reliability and performance.
- Expectation of Success: Success was expected because combining an engine with an alternator is a fundamental aspect of generator design. Furthermore, using a dual-stage regulator was a known solution to a known problem in LPG fuel systems, and Parlatore explicitly suggested its system could be used in generators.
Ground 3: Claims 1-3, 5-9, 11-14, 17-20, and 22-23 are anticipated by the Kubota DF972 Workshop Manual.
Prior Art Relied Upon: Kubota DF972-E2 Workshop Manual (“Workshop Manual”).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued the Workshop Manual, alleged to be a prior art printed publication under 35 U.S.C. §102, discloses every element of numerous challenged claims. The manual describes the Kubota DF972-E2 engine, a dual-fuel (gasoline/LPG) engine used in generators. It explicitly shows a "Gasoline Cut Off Solenoid" that controls fuel flow from the float chamber to the mixing chamber (i.e., downstream of the float bowl), an "LPG Cut Off Solenoid," and a "Fuel Select Switch" that controls both solenoids to switch between fuels. Petitioner further contended that the manual's description of on-the-fly switching, either explicitly or as informed by the accompanying Operator's Manual, meets those claim limitations. The manual also details a two-stage vaporizer with a "Primary Chamber" and "Secondary Chamber," which Petitioner argued inherently function as the claimed primary and secondary pressure regulators.
Additional Grounds: Petitioner asserted additional obviousness challenges, including: claims 4 and 10 over Nakafushi, Olmr, and Duffy (to add timed fuel overlap); claims 19-23 over Nakafushi, Olmr, and Bernhardsson/Duffy (to specify the gaseous valve as a solenoid and add features like on-the-fly switching); and claims based on the Workshop Manual in view of references like Duffy, Parlatore, and the Tri-Fuel Video to teach features such as timed fuel overlap and off-board regulator systems.
4. Relief Requested
- Petitioner requests institution of IPR and cancellation of claims 1-24 of Patent 10,393,034 as unpatentable.