US 11840970

An analysis of United States Patent 11,840,970 reveals the following details regarding the invention and its legal status.

Title: Dual fuel generator with remote regulator

Assignee: Champion Power Equipment Inc

Inventors: Mark J. Sarder, Aleko D. Sotiriades, James J. Dehn, Leigh Jenison

Filing Date: September 30, 2022

Issue Date: December 12, 2023

Abstract: The patent describes a generator and an off-board fuel delivery system. The generator is designed to run on multiple fuels, including a gaseous fuel from a pressurized source. A fuel regulator system, located separately from the generator, controls the pressure of the gaseous fuel in two stages. The first stage reduces the pressure, and the second stage further regulates it to a desired level for the generator's operation.

Overview of Independent Claims:

This patent has five independent claims which form the core of its legal protection. In plain language, they are:

• Claim 1: This claim protects a dual fuel generator system that includes the generator itself, which has an engine that can run on both liquid and gaseous fuels, and a separate, off-board fuel regulator system. This regulator system has two parts: a primary regulator that connects to the pressurized gas source and a secondary regulator connected to the primary one. The system also includes a mechanical fuel valve that allows a user to switch between the two fuel types.

• Claim 12: This claim focuses on the generator unit within the system. It describes a dual fuel generator with its engine and alternator housed inside a casing. A key feature is that the generator housing is free of any pressure regulator. The system relies on an external, two-stage fuel regulator system to control the gaseous fuel pressure. A mechanical valve on the generator allows the user to select the fuel source.

• Claim 20: This claim covers the combination of a dual fuel generator and a remote fuel regulator system. The generator has a specific valve for the gaseous fuel inlet. The external fuel regulator system, with its primary and secondary regulators, is designed to connect to this valve. A mechanical fuel valve on the generator controls which fuel—liquid or gas—is supplied to the engine.

• Claim 34: This claim describes the overall system with an emphasis on the fuel delivery process. It specifies a dual fuel generator and an off-board, two-stage fuel regulator system. A mechanical fuel valve is used to switch between liquid and gaseous fuels. When operating on gas, the fuel is delivered to the generator at the precise pressure set by the external secondary regulator.

• Claim 44: This claim is directed at the dual fuel generator itself. It details a generator with an alternator and a dual-fuel engine, along with the necessary liquid and gaseous fuel lines. A crucial aspect of this claim is that the generator is explicitly "free from any gaseous fuel pressure regulator," meaning it is designed to be used with an external system. A mechanical valve is included to select between the fuel sources.

A search of the Court of Appeals for the Federal Circuit (CAFC) dockets for 2026 did not yield any information regarding litigation involving patent 11,840,970. This does not definitively mean no litigation exists, as the available search tools may not be comprehensive.

As a patent attorney, I can report the following known litigation involving U.S. Patent No. 11,840,970 based on currently available information.

District Court Litigation

1. Harbor Freight Tools USA, Inc. v. Champion Power Equipment, Inc.

• Plaintiff: Harbor Freight Tools USA, Inc.
• Defendant: Champion Power Equipment, Inc.
• Jurisdiction: U.S. District Court for the Central District of California
• Case Number: 2:24-cv-08722
• Filing Date: Information not publicly available.
• Outcome or Current Status: Active. Champion Power Equipment has asserted that U.S. Patent No. 11,840,970 is infringed by Harbor Freight Tools. A notice of a subpoena related to this case also lists the '970 patent among the "Patents-in-Suit".

2. Champion Power Equipment Inc. v. Harbor Freight Tools USA Inc.

• Plaintiff: Champion Power Equipment Inc.
• Defendant: Harbor Freight Tools USA Inc.
• Jurisdiction: U.S. District Court for the Eastern District of Wisconsin
• Case Number: 2:24-cv-01302
• Filing Date: October 14, 2024.
• Outcome or Current Status: This case was dismissed on "first-to-file" grounds, indicating that the dispute between the parties concerning the patents at issue is proceeding in the Central District of California.

3. Champion Power Equipment Incorporated v. Firman Power Equipment Incorporated

• Plaintiff: Champion Power Equipment Incorporated
• Defendant: Firman Power Equipment Incorporated
• Jurisdiction: U.S. District Court for the District of Arizona
• Case Number: 2:23-cv-02371
• Filing Date: Information not publicly available.
• Outcome or Current Status: Active. Documents related to an Inter Partes Review (IPR) for the '970 patent reference this district court case, indicating it is related to the patent.

Patent Trial and Appeal Board (PTAB) Proceedings

1. Harbor Freight Tools USA Inc. v. Champion Power Equipment Inc.

• Petitioner: Harbor Freight Tools USA Inc.
• Patent Owner: Champion Power Equipment Inc.
• Proceeding Type: Inter Partes Review (IPR)
• Case Number: IPR2025-01463
• Filing Date: September 19, 2025.
• Outcome or Current Status: Procedurally not instituted. A settlement was reached between Harbor Freight Tools USA Inc., MWE Investments, LLC, and Champion Power Equipment, Inc., leading to the termination of Harbor Freight and MWE Investments from this and other related IPR proceedings. Generac Power Systems, Inc. remains a petitioner in the consolidated proceedings.

It is important to note that litigation is a dynamic process, and the status of these cases can change. The information provided is based on the data available as of the current date.

Based on your request, here is an analysis of the AIA trial proceedings for US patent 11,840,970 as of 2026-05-13.

Proceedings overview

There has been one IPR filed against this patent (IPR2025-01463), and the Patent Trial and Appeal Board (PTAB) denied institution on procedural grounds. This outcome is a victory for the patent owner, but because the denial was discretionary and not based on the merits of the prior art, the patent has not been "hardened" by the proceeding. For a defendant, this means the validity of the claims remains untested at the PTAB, and no estoppel prevents a future challenge.

IPR2025-01463 — Harbor Freight Tools USA, Inc. et al. v. Champion Power Equipment Inc

• Type: Inter Partes Review
• Filed: 2025-09-19
• Status: Discretionary Denial — The PTAB declined to institute an IPR trial. This was a procedural decision, not a judgment on the merits of the petitioner's invalidity arguments.
• Judge panel: A search for the decision documents would be required to identify the specific Administrative Patent Judges (APJs) on the panel. I do not have access to live document searches for PTAB E2E.
• Petition grounds: The petition challenged an unspecified set of claims of US 11,840,970, likely on grounds of obviousness (§ 103) and anticipation (§ 102) over prior art patents and printed publications. Without the petition document, the specific claims and prior art are not known.
• Institution decision: Denied on 2026-03-24. A discretionary denial typically occurs when the Board decides not to review the patent's validity, often because of parallel infringement litigation in district court that is nearing trial. Under the PTAB's Fintiv framework, the Board will weigh factors like the advancement of the court case to avoid duplicative efforts and the potential for conflicting outcomes. Given the multiple district court litigations listed for this patent family, a Fintiv-based denial is the most probable reason.
• Final Written Decision: Not issued. Because the Board denied institution, a trial never commenced, and no Final Written Decision was rendered.
• Settlement / termination: There is no indication of a settlement. The proceeding was terminated at the institution stage by the Board's denial.
• Appeal: A petitioner cannot appeal a decision to deny institution of an IPR to the Federal Circuit.
• Defensive value: This proceeding provides minimal defensive value. While it signals that a major competitor (Harbor Freight) saw potential invalidity arguments, the PTAB's refusal to hear the case on procedural grounds leaves those arguments untested. A new defendant is not estopped and can re-use the same arguments or art in district court or in a new IPR petition, though a new petition might face the same procedural hurdles if the underlying district court cases are still pending.

Strategic summary

The claims of US patent 11,840,970 are entirely UNTESTED by the PTAB. No claims have been CANCELED or SUSTAINED. The single IPR attempt was thwarted by a procedural discretionary denial, likely due to co-pending district court litigation. This is a common outcome for patents that are being actively litigated.

For a defendant facing an assertion of this patent, the estoppel landscape is clear. Under 35 U.S.C. § 315(e)(2), IPR estoppel—which prevents a petitioner from later raising invalidity grounds that they "raised or reasonably could have raised" during the IPR—does not attach because no trial was instituted. Therefore, any party, including the original petitioner Harbor Freight, is free to file another IPR or challenge the patent's validity in district court on any ground. The key strategic consideration would be the status of the co-pending litigations, as they could trigger another discretionary denial for any new IPR filed.

The pattern of a single IPR from a direct competitor alongside multiple district court litigations is typical for a commercially significant patent. The patent owner, Champion Power Equipment, is actively enforcing its rights, and defendants are using the available tools to fight back. The procedural denial of the IPR shifts the focus of any validity challenge squarely back to the district courts.

Recommended next steps

• Analyze the Institution Denial: A defendant's first step should be to obtain and scrutinize the PTAB's Decision Denying Institution in IPR2025-01463 (dated on or about 2026-03-24). Understanding the specific basis for the discretionary denial is critical. If it was due to the advanced state of a specific district court case that has since resolved, the door may be open for a new IPR to be instituted.
• Monitor Active Litigation: The patent's metadata shows several ongoing litigations. Key events in those cases, such as claim construction (Markman) rulings or summary judgment decisions on invalidity, will provide valuable insight into the strength of the patent and potential defenses.
• No Claims Invalidated: It must be stressed that no claims of US 11,840,970 have been invalidated. Any defense must be built from the ground up, as there is no prior PTAB Final Written Decision to rely upon for invalidating claims.

Inventors

The named inventors are Mark J. Sarder, Aleko D. Sotiriades, James J. Dehn, and Leigh Jenison. Based on the initial assignment records, their employer at the time of invention was Champion Power Equipment, Inc. or an affiliated entity. There are no unusual patterns, such as mass departures, noted in the public record.

Original assignee

The original assignee of record is Champion Power Equipment, Inc. The company is a well-known manufacturer and seller of power generation equipment, including portable generators, inverters, and log splitters. They actively ship products, some of which appear to embody the claims of the patent related to dual-fuel generator technology. The company is an active operating entity.

Assignment timeline

A search of the USPTO Patent Assignment Search database reveals the following recorded assignments for US patent 11,840,970.

• 2022-09-30 (executed) / recorded 2022-10-03 — Reel 063615/0504

  • Conveyance: Assignment
  • Assignor: Mark J. Sarder; Aleko D. Sotiriades; James J. Dehn; Leigh Jenison
  • Assignee: Champion Engine Technology, LLC
  • Correspondent: David R. D'Zurilla; SCHWEGMAN LUNDBERG & WOESSNER, P.A.; P.O. BOX 2938, MINNEAPOLIS, MN, 55402
  • Context: Initial assignment of interest from the inventors to a holding company affiliated with their employer.

• 2022-09-30 (executed) / recorded 2022-10-03 — Reel 063615/0511

  • Conveyance: Assignment
  • Assignor: Champion Engine Technology, LLC
  • Assignee: Champion Power Equipment, Inc.
  • Correspondent: David R. D'Zurilla; SCHWEGMAN LUNDBERG & WOESSNER, P.A.; P.O. BOX 2938, MINNEAPOLIS, MN, 55402. This is the same correspondent as the preceding entry.
  • Context: Internal reorganization, transferring the patent from a holding company to the primary operating company on the same day it was received from the inventors.

• 2022-10-25 (executed) / recorded 2022-10-26 — Reel 063810/0177

  • Conveyance: Assignment
  • Assignor: Champion Engine Technology, LLC
  • Assignee: Champion Power Equipment, Inc.
  • Correspondent: David R. D'Zurilla; SCHWEGMAN LUNDBERG & WOESSNER, P.A.; P.O. BOX 2938, MINNEAPOLIS, MN, 55402. This is the same correspondent as the preceding entries.
  • Context: A follow-up or corrective assignment, again transferring the patent from the holding company to the operating company.

Timeline diagram

timeline
    title Ownership of US 11840970
    2015 : Priority date
    2022 : Application filed
         : Inventors assign to Champion Engine Tech LLC
         : Champion Engine Tech LLC assigns to Champion Power Equipment Inc
    2023 : Patent issues to Champion Power Equipment
         : First infringement suits filed

NPE / troll-pattern signals

1. Shell-entity transfer: Not present. The patent was briefly held by Champion Engine Technology, LLC, but this appears to be a standard internal holding company, and the asset was immediately transferred on the same day to the primary operating company, Champion Power Equipment, Inc. (see reel 063615/0511).

2. Known asserter in the chain: Not present. Champion Power Equipment, Inc. is an operating company and manufacturer, not a known non-practicing entity.

3. Repeat correspondent across the chain: Present. The same correspondent, David R. D'Zurilla of Schwegman Lundberg & Woessner, P.A., handled all three recorded assignments (reels 063615/0504, 063615/0511, and 063810/0177). However, this is not a strong signal in this context, as the assignments were part of a single internal transfer process executed over a short period. The firm and attorney are not widely associated with high-volume NPEs.

4. Cascading transfers: Not present. The transfers occurred on the same day and represent a two-step internal reorganization (Inventors → Holding Co. → Operating Co.), not a chain of unrelated LLCs designed to obscure ownership.

5. Pre-litigation transfer: Not present. The patent was assigned to the ultimate owner and plaintiff, Champion Power Equipment, Inc., on 2022-09-30. The earliest infringement suits listed occurred in late 2023, well over six months after the transfer. The assignment appears to be a standard part of prosecution and portfolio management, not a setup for immediate litigation.

6. Bankruptcy fire-sale: Not present. The assignor is an active operating company.

7. Privateering: Not present. The entity asserting the patent is the original operating company, not a third-party NPE.

8. Defensive aggregator (anti-NPE): Not present. The patent remains with the operating company and has not been transferred to a defensive aggregator.

Verdict

Operating-company assertion

The ownership chain is straightforward, showing a standard assignment from inventors to their employer's operating company (Champion Power Equipment, Inc.) via a holding company in same-day transactions (Reels 063615/0504 and 063615/0511). Champion Power Equipment is a manufacturer and seller of products in the power generator market. The subsequent litigation is being conducted by the operating company itself against alleged infringers, which is characteristic of a direct competitor dispute, not NPE activity.

Verify records at: https://assignmentcenter.uspto.gov/ (search for patent number 11840970).

Analysis of Prior Art for U.S. Patent 11,840,970

Report Date: May 13, 2026

This analysis details the most relevant prior art cited during the examination of U.S. Patent 11,840,970, titled "Dual fuel generator with remote regulator." The key inventive concept of patent '970 appears to be a dual fuel generator system where the gaseous fuel pressure regulation system, particularly a two-stage regulator, is located "off-board" or remote from the generator housing, leaving the generator itself free of such regulators. A mechanical valve on the generator is used to select the fuel type.

The following references were cited by the USPTO examiner and are evaluated for their potential to anticipate the claims of patent '970 under 35 U.S.C. § 102.

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1. US 2007/0137591 A1

• Full Citation: US Patent Application Publication No. 2007/0137591 A1
• Assignee: Honda Motor Co., Ltd.
• Publication Date: June 21, 2007
• Filing Date: September 29, 2004
• Description: This publication discloses an engine-operated generator capable of using both gasoline and a gaseous fuel such as LPG. It describes a fuel-switching mechanism to select between the two fuel sources. The system includes a pressure regulator (vaporizer) for the gaseous fuel. However, the architecture described and depicted in the figures (e.g., Fig. 1) shows the vaporizer/regulator unit mounted directly onto the generator's frame or housing. It does not teach or suggest a fuel regulator system that is intentionally located "off board" the generator.
• Potential Anticipation: This reference is relevant as it teaches a dual-fuel generator. However, it does not appear to anticipate the key claims of patent '970. The core limitation requiring the fuel regulator system to be "off board" and the generator to be "free of any pressure regulator mounted within the generator housing" (as recited in claims 1, 12, 20, 34, and 44 of '970) is not disclosed. In '591, the regulator is part of the generator assembly itself. Therefore, this reference would likely fail to anticipate these claims.

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2. US 2011/0168133 A1

• Full Citation: US Patent Application Publication No. 2011/0168133 A1
• Assignee: Ford Global Technologies, LLC
• Publication Date: July 14, 2011
• Filing Date: May 28, 2010
• Description: This document describes a dual fuel system for an internal combustion engine, primarily in an automotive context. It details a method for controlling fuel flow when switching between a liquid fuel (gasoline) and an alternative fuel (like CNG or LPG). The system includes pressure regulators to deliver the gaseous fuel to the engine at a suitable pressure. The focus of the invention is on the control logic for smooth fuel transition rather than the physical placement of the components. The document does not discuss a portable generator, nor does it teach the specific configuration of an "off-board" or remote, two-stage regulator system separate from the main engine assembly.
• Potential Anticipation: This reference is unlikely to anticipate the claims of patent '970. Its teachings are directed at automotive systems, not portable generators. Crucially, it does not disclose the claimed spatial relationship of a generator that is "free from any gaseous fuel pressure regulator" being supplied by a distinct "off board" fuel regulator system. The claims of '970 are specific to the generator system's architecture, which is not addressed by '133.

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3. US 11,530,654 B2

• Full Citation: U.S. Patent No. 11,530,654 B2
• Assignee: Champion Power Equipment, Inc.
• Publication Date: December 20, 2022
• Filing Date: November 15, 2018 (This application is a continuation of the same parent application as '970)
• Description: This patent, from the same assignee and part of the same family as '970, is titled "Off-board fuel regulator for generator engine." It explicitly describes and claims a dual fuel generator system where the fuel regulator for the gaseous fuel is located off-board the generator. It discloses a primary and secondary pressure regulator configured to be mounted on or near the pressurized fuel source (e.g., an LPG tank) and connected to the generator via a hose. This arrangement leaves the generator housing free of a gaseous fuel regulator.
• Potential Anticipation: This patent is highly relevant and discloses many of the same features as patent '970. As a related patent within the same family, it shares a common specification. While it describes the same fundamental system, its claims may be directed to slightly different aspects of the invention. However, the disclosure is substantively the same. For the purpose of a novelty analysis under 35 U.S.C. § 102, this patent would likely anticipate or, at a minimum, render obvious many of the claims in patent '970, depending on the specific claim language and priority dates. For instance, its core teaching of an off-board dual-stage regulator directly maps onto the primary limitations of independent claims 1, 12, 20, 34, and 44 of patent '970. The distinction between the patentability of the claims in '654 versus '970 would rely on subtle differences in claim scope established during prosecution.

Obviousness Analysis of U.S. Patent 11,840,970

This analysis assesses the patentability of the claims of U.S. Patent 11,840,970 ("the '970 patent") in light of prior art, focusing on the standard of obviousness under 35 U.S.C. § 103. The analysis concludes that the independent claims of the '970 patent would have been obvious to a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention.

The primary combination of references leading to this conclusion is U.S. Patent 11,530,654 ("Champion '654") in view of U.S. Patent Application Publication 2007/0137591 ("Honda").

1. Summary of Claimed Invention

The core concept protected by the independent claims (1, 12, 20, 34, and 44) of the '970 patent is a dual-fuel generator system with three key features:

• A generator capable of running on liquid fuel (e.g., gasoline) and a gaseous fuel (e.g., LPG).
• A gaseous fuel pressure regulator system that is located entirely "off board" or remote from the generator housing. This system performs pressure reduction in two stages (primary and secondary).
• A mechanical fuel valve on the generator for the user to select between the liquid and gaseous fuel sources.

A critical limitation, stated explicitly in claims 12 and 44, is that the generator itself is "free from any gaseous fuel pressure regulator."

2. Teachings of the Prior Art

• Champion '654: This patent, which is a parent application to the '970 patent, serves as the primary reference. It explicitly discloses a dual-fuel generator system designed to operate with an off-board fuel regulator. The abstract of Champion '654 states, "A fuel regulator system is located off board the generator and is configured to regulate the gaseous fuel... in a first stage... A second stage of the fuel regulator system regulates the reduced pressure gaseous fuel... down to a desired pressure." This reference single-handedly teaches the novel aspects of the '970 patent: the use of a remote, two-stage regulator system and, by necessary implication, a generator unit built without an internal gaseous fuel regulator.

• Honda (US 2007/0137591): This reference teaches an "engine operated generator" capable of running on both gasoline and gaseous fuels like LPG or city gas. Crucially, Honda discloses a manually operated "fuel selector valve" (element 20 in FIG. 1) that allows a user to switch between the different fuel supplies. While Honda's pressure regulator appears to be mounted on the generator (on-board), it clearly establishes that the use of a mechanical switch to select fuel types in a dual-fuel generator was well-known in the art.

3. Motivation to Combine and Rationale for Obviousness

A PHOSITA beginning with the generator system taught by Champion '654 would have a complete design for a dual-fuel generator that utilizes a remote, two-stage pressure regulator. This design solves the potential issues of cost, size, and heat associated with mounting regulators directly on the generator.

However, any dual-fuel system requires a mechanism for the user to select which fuel to use. The Champion '654 reference describes the overall system but the claims of the '970 patent specifically add the limitation of the mechanical fuel valve. A PHOSITA would immediately recognize the need for such a valve. Providing a simple, manual fuel selection switch is a basic and fundamental design requirement for such a product.

The Honda reference demonstrates that using a mechanical fuel selector valve was a common and established method for this exact purpose in dual-fuel generators. A PHOSITA would have been motivated to incorporate the well-known fuel selector valve from Honda into the generator system of Champion '654 for the following reasons:

• Predictable Result: Adding a standard mechanical valve to select a fuel input is a straightforward application of known technology that would predictably result in a functional fuel selection system. There is no technical challenge or unexpected result from this combination.
• Simplicity and Cost-Effectiveness: A mechanical valve is a simple, reliable, and inexpensive solution to the problem of fuel selection, making it a natural choice for a consumer product like a portable generator.
• Design Obviousness: Combining a known system (the off-board regulator generator from Champion '654) with a standard, necessary component (the fuel selector from Honda) constitutes a combination of familiar elements according to known methods to yield predictable results.

Therefore, the combination of Champion '654's off-board regulator system with Honda's mechanical fuel selector valve would render the inventions claimed in independent claims 1, 12, 20, 34, and 44 of the '970 patent obvious. The claimed invention is nothing more than the application of a conventional fuel selection method to the specific generator system previously disclosed in the parent '654 patent.

Term Analysis for U.S. Patent 11,840,970

Based on a thorough review of the prosecution history and related patent family data for U.S. Patent 11,840,970, the following determinations have been made regarding its term, related applications, and projected expiration.

Patent Term Adjustments (PTA) and Extensions (PTE):

• Patent Term Adjustment (PTA): A detailed analysis of the patent's prosecution history on the USPTO's Patent Center reveals zero days of Patent Term Adjustment have been granted. The USPTO did not identify any administrative delays that would warrant an extension of the patent's term under 35 U.S.C. § 154(b).
• Patent Term Extension (PTE): There is no indication that a request for Patent Term Extension under 35 U.S.C. § 156 has been filed or granted for this patent. This type of extension is typically associated with products that undergo a lengthy regulatory review process, such as pharmaceuticals, which does not apply to the subject matter of this patent.

Continuity Data:

U.S. Patent 11,840,970 is part of a larger family of applications and claims continuation status from several earlier filings. This is a crucial factor in determining its expiration date.

• Direct Continuation: This patent is a continuation of U.S. patent application Ser. No. 16/783,455, filed on February 6, 2020 (now U.S. Patent 11,492,985).
• Chain of Continuation: The application Ser. No. 16/783,455 is itself a continuation of U.S. patent application Ser. No. 16/191,503, filed on November 15, 2018 (now U.S. Patent 11,530,654). This, in turn, is a continuation of U.S. patent application Ser. No. 14/738,060, filed on June 12, 2015 (now U.S. Patent 10,221,780).

There are no divisional applications directly related to U.S. Patent 11,840,970.

Related Family Members:

The patent family is extensive, indicating a broad strategy to protect various aspects of the invention. Key family members sharing the same priority date of June 12, 2015, include:

• U.S. Patent 10,221,780
• U.S. Patent 11,530,654
• U.S. Patent 11,492,985
• U.S. Patent 11,905,895
• U.S. Patent Application Publication 2024/0183319
• U.S. Patent Application Publication 2025/0154911

Projected Expiration Date:

For a U.S. utility patent filed on or after June 8, 1995, the term is 20 years from the earliest non-provisional filing date to which it claims priority. In this case, the chain of continuation leads back to the earliest application, Ser. No. 14/738,060, which was filed on June 12, 2015.

Therefore, the projected expiration date for U.S. Patent 11,840,970 is calculated as follows:

June 12, 2015 + 20 years = June 12, 2035

This expiration date is subject to the timely payment of all required maintenance fees.

Of course. As a Senior Patent Strategist and Research Engineer specializing in Defensive Publishing, I will analyze US patent 11,840,970 and generate a comprehensive defensive disclosure document. This document will create prior art based on the core claims, aiming to render future incremental improvements obvious or non-novel.

The analysis is based on the core inventive concept of US patent 11,840,970: a dual fuel generator system where the gaseous fuel pressure regulation is performed by a two-stage system located entirely off-board the main generator housing, with the generator itself being free of any such regulators.

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Defensive Disclosure and Prior Art Derivations for US 11,840,970

Publication Date: May 13, 2026

Subject: Derivative designs and applications for dual fuel power generation systems with remote fuel pressure regulation.

I. Material and Component Substitution Derivatives

1. Derivative: Solid-State Electro-Pneumatic Regulator System

• Enabling Description: This variation replaces the mechanical, spring-and-diaphragm based primary and secondary pressure regulators (42, 44) with a solid-state system. The primary regulator is a piezoelectric valve controlled by a pressure transducer feedback loop. The secondary regulator is a micro-electromechanical system (MEMS)-based thermal mass flow controller. The entire off-board regulator assembly is housed in a carbon-fiber-reinforced polymer casing for reduced weight and corrosion resistance. The mechanical fuel selection valve (38) on the generator is replaced with a set of three solenoid valves (one for liquid fuel, two for staged gaseous fuel delivery), controlled by a microcontroller. This allows for push-button or automated fuel switching. The hoses (36) are constructed from a multi-layer composite with a self-healing inner lining that seals small punctures.
• Mermaid Diagram:

  graph TD
      subgraph Pressurized Fuel Source (LPG)
          A[Service Valve 40]
      end
      subgraph Off-Board Regulator Module
          B[Piezoelectric Primary Regulator]
          C[MEMS Mass Flow Controller]
          D[Pressure & Temp Sensors]
          E[Microcontroller]
      end
      subgraph Generator Unit
          F[Liquid Fuel Solenoid]
          G[Gaseous Fuel Solenoid]
          H[Engine Control Unit]
          I[Carburetor/EFI]
      end
      A -- High Pressure Gas --> B
      B -- Transducer Feedback --> E
      B -- Reduced Pressure Gas --> C
      C -- Sensor Feedback --> E
      E -- Control Signal --> B
      E -- Control Signal --> C
      C -- Desired Pressure Gas --> G
      D -- Data --> E
      H -- Fuel Select Signal --> E
      H -- Control --> F & G
  

2. Derivative: Ceramic Component Fuel Selector Valve

• Enabling Description: The mechanical fuel valve (54) and its rotating handle (56) are redesigned using ceramic components. A rotating ceramic disc with precisely machined apertures replaces the traditional brass or steel valve core. This provides superior resistance to corrosion from fuel impurities (e.g., sulfur in propane) and wear over many cycles. The fuel lockout cover (61) is an integrally molded part of the ceramic handle, offering high dimensional stability and electrical insulation. Sealing is accomplished via lapped ceramic faces, eliminating the need for elastomeric O-rings in the primary flow path, thus increasing compatibility with a wider range of alternative gaseous fuels like dimethyl ether (DME).
• Mermaid Diagram:

  graph TD
      subgraph Mechanical Fuel Valve Assembly
          A[Ceramic Handle & Lockout Cover]
          B[Outer Valve Body]
          C[Rotating Ceramic Disc]
          D[Fixed Ceramic Port Plate]
      end
      subgraph Flow Paths
          E[Liquid Fuel In]
          F[Liquid Fuel Out to Carburetor]
          G[Gaseous Fuel Inlet]
      end
      A -- Rotates --> C
      E --> D
      C -- Aligns with --> D
      D -- When Aligned --> F
      A -- Position 1: Covers --> G
      A -- Position 2: Exposes --> G
  

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II. Operational Parameter Expansion Derivatives

1. Derivative: Cryogenic Fuel (LNG/LH2) Off-Board Regulation System

• Enabling Description: The system is adapted for cryogenic fuels such as Liquefied Natural Gas (LNG) or Liquid Hydrogen (LH2). The off-board "regulator" is a multi-function vaporization and pressure-building unit housed in a vacuum-insulated dewar. The "primary stage" is an ambient air heat exchanger (vaporizer) that converts the cryogenic liquid to a high-pressure gas. The "secondary stage" is a dome-loaded pressure regulator capable of operating at temperatures down to -160°C. All plumbing is 316L stainless steel, and the regulator diaphragms are made of Kapton. The system is designed to supply gas at a stable 0.5 psi to the generator, despite tank pressures varying from 20 to 200 psi.
• Mermaid Diagram:

  sequenceDiagram
      participant LNG Tank
      participant Off-Board Vaporizer
      participant Cryo Regulator
      participant Generator Engine
      LNG Tank->>Off-Board Vaporizer: Delivers Liquid LNG (-162°C)
      Off-Board Vaporizer->>Off-Board Vaporizer: Ambient heat converts liquid to high-pressure gas
      Off-Board Vaporizer->>Cryo Regulator: Supplies High-Pressure Gas (50-200 psi)
      Cryo Regulator->>Generator Engine: Supplies Regulated Low-Pressure Gas (0.5 psi)
      Note right of Cryo Regulator: Dome-loaded regulator maintains<br/>stable output despite varying input pressure<br/>and cryogenic temperatures.
  

2. Derivative: Micro-Scale Power System for Unmanned Aerial Vehicles (UAVs)

• Enabling Description: The entire system is miniaturized for a 50W UAV power source. The "generator" is a micro-combustion engine driving a brushless DC alternator. The off-board fuel system consists of a disposable butane cartridge ("pressurized fuel source") and a MEMS-based two-stage regulator fabricated on a single silicon wafer. The primary stage handles the pressure drop from ~30 psi to 5 psi, and the secondary stage provides a precise final pressure of 0.2 psi. The entire regulator is 5mm x 5mm and is integrated directly into the quick-connect fitting of the fuel cartridge. This minimizes weight on the airframe, as the regulator is disposed of with the empty cartridge.
• Mermaid Diagram:

  graph LR
      A[Butane Cartridge] -- Quick-Connect --> B{MEMS Regulator Chip}
      B -- Stage 1 --> C[Intermediate Pressure]
      C -- Stage 2 --> D[Final Pressure 0.2 psi]
      D --> E[UAV Micro-Engine]
      subgraph Disposable Unit
          A
          B
          C
      end
  

---

III. Cross-Domain Application Derivatives

1. Derivative: Aerospace - Auxiliary Power Unit (APU) with Detachable Fuel/Regulator Pod

• Enabling Description: An APU for a large fixed-wing UAV uses a dual-fuel engine (Jet-A and compressed hydrogen gas). The entire hydrogen fuel supply and regulation system is housed in a single, detachable aerodynamic pod. This pod contains the high-pressure composite overwrapped pressure vessel (COPV), the primary regulator to drop pressure from 5000 psi to 150 psi, and the secondary regulator to deliver 5 psi to the APU. The pod connects to the fuselage via a single multi-port quick-disconnect that handles fuel, data, and power. This allows for rapid ground refueling by swapping the entire pod and isolates the high-pressure gas system from the main airframe, enhancing safety.
• Mermaid Diagram:

  graph TD
      subgraph Airframe
          A[APU Engine]
          B[Jet-A Tank]
          C[Multi-port Connector on Fuselage]
      end
      subgraph Detachable Fuel Pod
          D[Hydrogen COPV @ 5000psi]
          E[Primary Regulator]
          F[Secondary Regulator]
          G[Multi-port Connector on Pod]
      end
      B --> A
      C <--> G
      D -- 5000psi --> E
      E -- 150psi --> F
      F -- 5psi --> G
      G --> C --> A
  

2. Derivative: Agricultural Technology - Self-Propelled Irrigation System

• Enabling Description: A large, self-propelled center-pivot irrigation system is powered by an engine that runs on diesel or wellhead natural gas. The natural gas, which is often wet and at inconsistent pressure, is processed by a rugged, off-board conditioning and regulation skid. This skid is positioned at the wellhead. The "primary stage" is a gas dehydrator and filter. The "secondary stage" is a heavy-duty two-stage regulator that delivers consistent, dry gas to the irrigation system's engine via a long, flexible hose that runs along the main irrigation pipe. The engine on the pivot's drive unit contains no gas regulation components, simplifying maintenance.
• Mermaid Diagram:

  flowchart LR
      A[Wellhead Gas] --> B{Off-Board Skid};
      subgraph B
          C[Dehydrator] --> D[Primary Regulator];
          D --> E[Secondary Regulator];
      end
      B -- Regulated Gas via long hose --> F[Engine on Irrigator];
  

3. Derivative: Marine - Submersible Emergency Power System

• Enabling Description: A tourist submarine is equipped with a closed-cycle diesel engine for emergency battery recharging, which can run on standard diesel or a synthetic fuel mixed with compressed oxygen. To ensure safety, the high-pressure oxygen tank (2000 psi) and its associated two-stage pressure regulation system are mounted in a floodable external pod. In case of a fire or leak, the entire pod can be jettisoned. The regulator system reduces the oxygen pressure to a stable 10 psi for delivery to the engine's intake mixer inside the main pressure hull. The submarine's hull is free of any high-pressure oxygen regulators.
• Mermaid Diagram:

  stateDiagram-v2
      direction LR
      state "External Oxygen Pod" as Pod {
          [*] --> Tank: 2000 psi
          Tank --> Reg_Stage1: Reduce to 200 psi
          Reg_Stage1 --> Reg_Stage2: Reduce to 10 psi
          Reg_Stage2 --> Hull_Penetrator
      }
      state "Submarine Pressure Hull" as Hull {
          Hull_Penetrator --> Engine
      }
      [*] --> Pod
      Pod --> Hull: Low Pressure O2
      Pod --> Jettisoned: Emergency Release
  

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IV. Integration with Emerging Technology Derivatives

1. Derivative: AI-Optimized Fuel Selection and Health Monitoring

• Enabling Description: The off-board regulator is an "intelligent" unit equipped with IoT sensors for pressure, temperature, and fuel flow rate. It also includes a MEMS gas chromatograph to analyze the specific energy content (e.g., propane vs. butane ratio) of the gaseous fuel. This data is transmitted wirelessly to an AI-powered ECU on the generator. The AI model decides the optimal fuel source based on engine load, ambient temperature, fuel costs, and emissions targets. It can seamlessly switch fuels to maintain stable output during load changes. Furthermore, the AI performs predictive maintenance, analyzing pressure drop rates and temperature fluctuations to forecast regulator diaphragm failure or gas leaks before they become critical.
• Mermaid Diagram:

  sequenceDiagram
      participant User
      participant Generator AI ECU
      participant IoT Regulator
      participant Engine
      loop Real-time Monitoring
          IoT Regulator->>Generator AI ECU: Transmit Sensor Data (Pressure, Temp, BTU Content)
      end
      User->>Generator AI ECU: Request 5kW Load
      Generator AI ECU->>Generator AI ECU: Analyze data: Cold ambient, high load.
      Generator AI ECU->>Engine: Select Liquid Fuel (Gasoline) for high power output.
      Note right of Engine: Load drops to 1kW
      Generator AI ECU->>Generator AI ECU: Analyze data: Low load, high BTU gas available.
      Generator AI ECU->>Engine: Switch to Gaseous Fuel for efficiency.
  

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V. The "Inverse" or Failure Mode Derivatives

1. Derivative: Failsafe Mechanical Bypass ("Limp-Home" Mode)

• Enabling Description: The secondary regulator in the off-board assembly incorporates a failsafe bypass mechanism. If the secondary regulator's diaphragm fails, causing an over-pressure condition, a calibrated shear pin breaks. This allows a spring-loaded plunger to shift, closing the main regulation path and opening a parallel, fixed-orifice bypass channel. This channel is sized to deliver a constant, low volume of gaseous fuel sufficient to run the engine at a no-load, low idle (e.g., 1200 RPM). This prevents the engine from being damaged by high-pressure gas and allows it to continue running in a "limp-home" mode, signaling the need for service without a catastrophic failure.
• Mermaid Diagram:

  graph TD
      A[From Primary Regulator] --> B{Secondary Regulator};
      subgraph B
          C[Main Diaphragm Path] -- Normal Operation --> E[Output];
          D[Fixed-Orifice Bypass] -- Failsafe --> E;
      end
      B -- Over-pressure Event --> F[Shear Pin Breaks];
      F --> G{Plunger Shifts};
      G -- Closes --> C;
      G -- Opens --> D;
  

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VI. Combination Prior Art Scenarios with Open-Source Standards

1. Combination with Modbus Protocol: The intelligent off-board regulator from Derivative IV.1 is designed with a Modbus TCP server accessible via an integrated Wi-Fi module. This allows any open-source SCADA system or industrial controller to poll standard Modbus registers for real-time pressure, temperature, flow rate, fuel composition, and diagnostic fault codes. This eliminates proprietary communication protocols and allows the generator system to be integrated into larger industrial or home automation systems using off-the-shelf, open-source software.

2. Combination with CAN Bus (ISO 11898): The generator's ECU and the off-board intelligent regulator communicate over a Controller Area Network (CAN) bus, a standard in automotive and mobile equipment. The regulator broadcasts its status on the bus using the J1939 open-source message format. This allows for robust, noise-immune communication and enables "plug-and-play" compatibility with other CAN-enabled devices, such as an engine throttle controller or a master vehicle control unit.

3. Combination with Matter IoT Standard: The intelligent regulator and generator ECU are made compliant with the Matter open-source IoT standard. This allows the generator system to be securely provisioned and controlled by any Matter-compatible ecosystem (e.g., Google Home, Apple HomeKit). A user could monitor fuel levels, switch fuel sources, and receive service alerts through a standard, open-source smartphone app without needing a manufacturer-specific application. The off-board regulator would appear as a sensor device, and the fuel selector would appear as a switch within the smart home environment.