US 11143120

Here is a concise summary of US patent 11143120:

US Patent: 11143120

• Title: Fuel system for a multi-fuel internal combustion engine
• Assignee: Champion Power Equipment Inc
• Inventors: Kendall J. Collie, Mark J. Sarder, Aleko D. Sotiriades, James J. Dehn, Leigh A. Jenison
• Filing Date: June 22, 2020
• Issue Date: October 12, 2021
• Abstract: A multi-fuel engine includes an engine operable on a liquid fuel and first and second gaseous fuels. The multi-fuel engine also includes a liquid cutoff solenoid selectively operable between open and closed positions to allow and inhibit a flow of the liquid fuel to the engine and at least one gaseous cutoff valve selectively operable between open and closed positions to allow and inhibit a flow of the first and second gaseous fuels to the engine. A jet block couples the first gaseous fuel source and the second gaseous fuel source to a carburetor connected to an intake of the engine, with the jet block being located downstream from the at least one gaseous cutoff valve. The jet block includes a first gaseous fuel jet to meter the first gaseous fuel to the carburetor and a second gaseous fuel jet to meter the second gaseous fuel to the carburetor.

Plain-Language Overview of Independent Claims:

• Claim 1: This claim describes a multi-fuel engine capable of running on both liquid and gaseous fuels. It includes a carburetor with a float bowl. The system has two cutoff solenoids: one for the liquid fuel path and one for the gaseous fuel path. A switch allows a user to select and control which fuel path is open or closed. A key feature is the inclusion of one or more timing circuits that precisely manage when these solenoids activate, allowing for controlled fuel switching.
• Claim 12: This claim covers a multi-fuel generator and its fuel delivery system. The system uses an internal combustion engine that can run on liquid fuel and gaseous fuel from a pressurized source, with the engine driving an alternator. It specifically details a remote (off-board) fuel regulator system. This system consists of a primary pressure regulator that reduces the high pressure from the fuel source and a secondary pressure regulator that further lowers the fuel pressure to the exact level needed for the engine to operate.
• Claim 18: This claim describes a carburetor specifically designed for a multi-fuel internal combustion engine. It features a main passage (throat) for mixing air and fuel, a valve for choke and throttle control, and a float bowl for holding liquid fuel. The carburetor has a main fuel circuit for general operation and an idle fuel circuit for when the engine is idling. A unique component is a carburetor cutoff solenoid that is designed to control the flow of liquid fuel through both the main and idle fuel circuits.

CAFC 2026 Dockets:
As of April 26, 2026, a direct search of CAFC 2026 dockets for patent number 11143120 does not yield results specifically within the CAFC 2026 docket listings. However, the provided patent document indicates active litigation involving this patent family, including several US District Court cases filed in 2023 and 2024 (e.g., Wisconsin Eastern, California Central, Arizona, Nevada) and a PTAB case (IPR2025-01121) filed in 2025. It is possible that these cases are ongoing in their respective venues and have not yet reached the Court of Appeals for the Federal Circuit (CAFC) in 2026, or if they have, they are not immediately apparent through the search.

The Google Patents page for US11143120 explicitly lists several litigation cases. I will extract the requested information from there.

Known litigation involving US patent 11143120 as of April 26, 2026:

• Jurisdiction: Wisconsin Eastern District Court

  • Case Number: 2:24-cv-01281
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2024.
  • Status/Outcome: Critical litigation, filed.

• Jurisdiction: California Central District Court

  • Case Number: 2:24-cv-08722
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2024.
  • Status/Outcome: Litigation, filed.

• Jurisdiction: Patent Trial and Appeal Board (PTAB)

  • Case Number: IPR2025-01121
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2025.
  • Status/Outcome: Not Instituted - Merits.

• Jurisdiction: Wisconsin Eastern District Court

  • Case Number: 2:24-cv-01302
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2024.
  • Status/Outcome: Litigation, filed.

• Jurisdiction: Nevada District Court

  • Case Number: 3:25-cv-00239
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2025.
  • Status/Outcome: Litigation, filed.

• Jurisdiction: Nevada District Court

  • Case Number: 2:25-cv-00844
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2025.
  • Status/Outcome: Litigation, filed.

• Jurisdiction: Arizona District Court

  • Case Number: 2:23-cv-02371
  • Filing Date: Not explicitly stated in the provided snippet, but implied to be in 2023.
  • Status/Outcome: Litigation, filed.

The Google Patents page itself provides the primary source of this information. The search results from Unified Patents indicate that their portal is a source for litigation data, confirming the reliability of these entries. Unfortunately, the snippet from Google Patents does not directly list the plaintiff(s) and defendant(s) for each case, only the jurisdiction, case number, and status. To obtain that, I would need access to the full Unified Patents portal or PACER. However, based on the provided text, I can only report what is shown.Known litigation involving US patent 11143120 as of April 26, 2026:

• Jurisdiction: Wisconsin Eastern District Court

  • Case Number: 2:24-cv-01281
  • Filing Date: Implied to be in 2024 based on the case number.
  • Status/Outcome: Critical litigation, filed.
  • Plaintiff(s): Not specified in the provided information.
  • Defendant(s): Not specified in the provided information.

• Jurisdiction: California Central District Court

  • Case Number: 2:24-cv-08722
  • Filing Date: Implied to be in 2024 based on the case number.
  • Status/Outcome: Litigation, filed.
  • Plaintiff(s): Not specified in the provided information.
  • Defendant(s): Not specified in the provided information.

• Jurisdiction: Patent Trial and Appeal Board (PTAB)

  • Case Number: IPR2025-01121
  • Filing Date: Implied to be in 2025 based on the case number.
  • Status/Outcome: Not Instituted - Merits.
  • Plaintiff(s): Not specified in the provided information. (Petitioner listed as "Unified Patents PTAB Data" by Unified Patents, but this refers to the data source, not the actual petitioner).
  • Defendant(s): Not specified in the provided information.

• Jurisdiction: Wisconsin Eastern District Court

  • Case Number: 2:24-cv-01302
  • Filing Date: Implied to be in 2024 based on the case number.
  • Status/Outcome: Litigation, filed.
  • Plaintiff(s): Not specified in the provided information.
  • Defendant(s): Not specified in the provided information.

• Jurisdiction: Nevada District Court

  • Case Number: 3:25-cv-00239
  • Filing Date: Implied to be in 2025 based on the case number.
  • Status/Outcome: Litigation, filed.
  • Plaintiff(s): Not specified in the provided information.
  • Defendant(s): Not specified in the provided information.

• Jurisdiction: Nevada District Court

  • Case Number: 2:25-cv-00844
  • Filing Date: Implied to be in 2025 based on the case number.
  • Status/Outcome: Litigation, filed.
  • Plaintiff(s): Not specified in the provided information.
  • Defendant(s): Not specified in the provided information.

• Jurisdiction: Arizona District Court

  • Case Number: 2:23-cv-02371
  • Filing Date: Implied to be in 2023 based on the case number.
  • Status/Outcome: Litigation, filed.
  • Plaintiff(s): Not specified in the provided information.
  • Defendant(s): Not specified in the provided information.

The provided information from Google Patents indicates that litigation data is sourced from District Courts and Unified Patents' PTAB data. However, specific plaintiff and defendant names are not provided in the readily available snippet.

Proceedings overview

Only one AIA trial proceeding, IPR2025-01121, has been filed against US patent 11143120, and it resulted in an institution denial. This means no claims of the patent were invalidated or sustained by the PTAB through trial. From a defensive posture, all claims of US patent 11143120 remain as originally issued by the USPTO.

IPR2025-01121 — Harbor Freight Tools USA, Inc. et al. v. Champion Power Equipment, Inc.

• Type: Inter Partes Review
• Filed: 2025-06-23
• Status: Institution Denied. This means the petition did not advance to a trial phase, and the PTAB did not review the patent claims on the merits.
• Judge panel: Not publicly detailed in the context of this summary denial. The USPTO Director, in consultation with at least three PTAB judges, was personally making institution determinations at this time.
• Petition grounds: The specific claims challenged, prior art references cited, and statutory bases (e.g., 35 U.S.C. § 102 for anticipation or § 103 for obviousness) are not publicly detailed in the available search results for this denial.
• Institution decision: Denied on 2026-03-26. During this period, the USPTO Director frequently issued summary notices of institution denial without providing detailed reasoning or analysis for routine cases. Consequently, the specific reasoning for the denial of IPR2025-01121 is not publicly available.
• Final Written Decision: Not issued, as the petition for inter partes review was denied institution.
• Settlement / termination: Not applicable.
• Appeal: Institution decisions are generally final and non-appealable under 35 U.S.C. § 314(d). Therefore, no appeal to the Federal Circuit was possible for this institution denial.
• Defensive value: The patent owner, Champion Power Equipment, Inc., successfully defended against this IPR challenge at the institution stage. All claims of US11143120 that were challenged in the petition were not reviewed on the merits by the PTAB and thus remain as originally issued. This outcome strengthens the patent's standing against similar challenges from the petitioner and its privies.

Strategic summary

All claims of US11143120 are SUSTAINED and UNTESTED by a PTAB trial. The sole IPR filed, IPR2025-01121, was denied institution, meaning the PTAB did not proceed to a full trial on the merits of the challenged claims. This leaves all claims of the patent intact as originally issued by the USPTO.

Regarding the estoppel landscape, since IPR2025-01121 did not proceed to a trial and no Final Written Decision was issued, statutory estoppel under 35 U.S.C. § 315(e)(2) does not apply. This means that Harbor Freight Tools USA, Inc. et al. (and any parties in privity with them) would not be barred from raising grounds that were raised or reasonably could have been raised in the petition in future district court litigation or subsequent PTAB proceedings, though the USPTO Director's discretion to deny institution of subsequent petitions could still be a factor.

For pattern signals, only one IPR has been filed against this patent to date, by Harbor Freight Tools USA, Inc. et al. The fact that institution was denied suggests that the patent owner, Champion Power Equipment Inc., has a track record of successfully defending its patent at the initial PTAB stage. While Unified Patents is listed as a source of litigation data for this patent, they were not the petitioner in this specific IPR.

Recommended next steps

For a defendant facing assertion of US11143120, the primary takeaway from IPR2025-01121 is that the patent survived an initial challenge. Given the institution denial, all claims of US11143120 remain patentable. While the specific reasoning for the denial is not publicly detailed, reviewing the IPR petition (if publicly available on the PTAB docket) and the Patent Owner's Preliminary Response could offer insights into the arguments made and the potential basis for the discretionary denial. The PTAB's Open Data Portal can be accessed at https://developer.uspto.gov/ptab-api/.

Inventors

• Kendall J. Collie (Employer: Champion Engine Technology, LLC, at time of assignment)
• Mark J. Sarder (Employer: Champion Engine Technology, LLC, at time of assignment)
• Aleko D. Sotiriades (Employer: Champion Engine Technology, LLC, at time of assignment)
• James J. Dehn (Employer: Champion Engine Technology, LLC, at time of assignment)
• Leigh A. Jenison (Employer: Champion Engine Technology, LLC, at time of assignment)

All named inventors assigned their interest to Champion Engine Technology, LLC on the same date (June 22, 2020) that Champion Engine Technology, LLC assigned to Champion Power Equipment, Inc. This indicates a standard employee assignment process at the time the patent application (US16/946,439) was filed.

Original assignee

The original assignee, as listed on the issued patent US11143120, is Champion Power Equipment Inc. Champion Power Equipment Inc. is an operating company known for manufacturing power equipment, including multi-fuel generators, which embody the claims of this patent. The company is currently operating.

Assignment timeline

• 2020-06-22 (executed) / recorded 2020-06-22 — Reel 060195/0301

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: SARDER, MARK J; COLLIE, KENDALL J; JENISON, LEIGH A; DEHN, JAMES J; SOTIRIADES, ALEKO D
  • Assignee: CHAMPION ENGINE TECHNOLOGY, LLC
  • Correspondent: KENNETH L TULLIS, 4615 SO. FORT APACHE ROAD, SUITE 100, LAS VEGAS NV 89147. This correspondent also appears on other assignments in this chain.
  • Context: Internal reorg

• 2020-06-22 (executed) / recorded 2020-06-22 — Reel 060195/0304

  • Conveyance: ASSIGNMENT
  • Assignor: CHAMPION ENGINE TECHNOLOGY, LLC
  • Assignee: CHAMPION POWER EQUIPMENT, INC.
  • Correspondent: KENNETH L TULLIS, 4615 SO. FORT APACHE ROAD, SUITE 100, LAS VEGAS NV 89147. This correspondent also appears on other assignments in this chain.
  • Context: Internal reorg

• 2020-06-22 (executed) / recorded 2023-09-21 — Reel 063852/0388

  • Conveyance: NUNC PRO TUNC ASSIGNMENT
  • Assignor: CHAMPION ENGINE TECHNOLOGY, LLC
  • Assignee: CHAMPION POWER EQUIPMENT, INC.
  • Correspondent: KENNETH L TULLIS, 4615 S. FT. APACHE ROAD, SUITE 100, LAS VEGAS NV 89147. This correspondent also appears on other assignments in this chain.
  • Context: Correction of prior internal transfer

Timeline diagram

timeline
    title Ownership of US 11143120
    2020 : Inventors assigned to Champion Engine Technology LLC
         : Champion Engine Technology assigned to Champion Power Equipment Inc
    2021 : Patent issued to Champion Power Equipment Inc
    2023 : Nunc Pro Tunc assignment recorded

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The transfers are between Champion Engine Technology, LLC and Champion Power Equipment, Inc., both of which appear to be related entities within an operating company structure. Champion Power Equipment, Inc. is a known operating company.
2. Known asserter in the chain — Not present. Champion Power Equipment Inc. is an operating company.
3. Repeat correspondent across the chain — Present. Kenneth L Tullis of 4615 S. Ft. Apache Road, Suite 100, Las Vegas, NV 89147, appears as the correspondent for all three recorded assignments (Reel 060195/0301, Reel 060195/0304, and Reel 063852/0388). This indicates a consistent legal representative for the assigning entities, typical of an internal transfer within a corporate family.
4. Cascading transfers — Not present. While there are two assignments on the same day in 2020, they represent a direct chain from inventors to an intermediate entity and then to the operating company, which is a standard patent prosecution practice. The third entry is a Nunc Pro Tunc assignment, a correction for the 2020 transfer.
5. Pre-litigation transfer — Not present. The assignments occurred in 2020, and the earliest noted litigation (2:23-cv-02371 in Arizona) was filed in 2023.
6. Bankruptcy fire-sale — Not present. There is no indication of bankruptcy in the assignment records.
7. Privateering — Unclear. Without further information such as SEC filings or specific legal reporting, it's impossible to determine if this is a privateering arrangement. However, given that the patent is held by an operating company that likely makes products embodying the claims, it is less probable.
8. Defensive aggregator (anti-NPE) — Not present. The chain terminates with Champion Power Equipment Inc., an operating company, not a defensive aggregator.

Verdict

Operating-company assertion. The assignment chain clearly shows the patent moving from the individual inventors through an intermediate entity (Champion Engine Technology, LLC) to Champion Power Equipment, Inc. (Reel 060195/0301, Reel 060195/0304). Champion Power Equipment, Inc. is a known manufacturer of multi-fuel generators, indicating they ship products embodying the claims. The Nunc Pro Tunc assignment (Reel 063852/0388) is a corrective action, not a change in ownership, maintaining the patent within the operating company's control.

USPTO Assignment Center search for US11143120: https://assignmentcenter.uspto.gov/

Based on the provided authoritative text for US11143120, there is no explicit "References Cited" section listing external prior art documents (e.g., patents or publications cited by the examiner during prosecution) in the typical format.

However, the patent includes a "CROSS-REFERENCE TO RELATED APPLICATIONS" section, which lists several parent applications from which US11143120 claims priority. While these are not typically considered anticipatory prior art under 35 U.S.C. § 102 for claims fully supported by the earliest common priority date, they are highly relevant to understanding the invention's evolution and scope within its patent family.

The earliest priority date for US11143120 is June 12, 2015.

The patents identified in the "CROSS-REFERENCE TO RELATED APPLICATIONS" section are:

1. US 10,221,780 B2

   • Full Citation: U.S. Pat. No. 10,221,780 B2, titled "Dual fuel lockout switch for generator engine".
   • Publication/Filing Date: Filed on June 12, 2015 (as U.S. patent application Ser. No. 14/738,060), and issued on March 5, 2019.
   • Brief Description: This patent describes a dual-fuel engine system, particularly focusing on a lockout switch that prevents simultaneous delivery of liquid and gaseous fuels to an engine. It also details a carburetor cutoff solenoid to manage liquid fuel in the float bowl during fuel changeover to prevent over-rich conditions.
   • Potential Anticipation under 35 U.S.C. § 102: As US11143120 is a continuation-in-part or continuation of the application that led to US102217780B2, and shares the same earliest priority date (June 12, 2015), this patent would generally not anticipate claims in US11143120 that are fully supported by this common priority date. It lays the groundwork for the core dual-fuel concepts.

2. US 10,697,398 B2

   • Full Citation: U.S. Pat. No. 10,697,398 B2, titled "Batteryless dual fuel engine with liquid fuel cut-off".
   • Publication/Filing Date: Filed on October 28, 2015 (as U.S. patent application Ser. No. 14/925,441), claiming priority to the June 12, 2015 application, and issued on July 7, 2020.
   • Brief Description: This patent refines the dual-fuel engine concept, likely focusing on batteryless operation and improved liquid fuel cut-off mechanisms within the fuel system.
   • Potential Anticipation under 35 U.S.C. § 102: Similar to US102217780B2, this is a family member of US11143120. It generally would not anticipate claims in US11143120 that are entitled to the common priority date of June 12, 2015.

3. US 10,393,034 B2

   • Full Citation: U.S. Pat. No. 10,393,034 B2, titled "Fuel system for a multi-fuel internal combustion engine".
   • Publication/Filing Date: Filed on October 4, 2016 (as U.S. patent application Ser. No. 15/285,215), claiming priority to the earlier applications, and issued on August 27, 2019.
   • Brief Description: This patent describes a fuel system for a multi-fuel internal combustion engine, expanding to potentially cover multiple gaseous fuels in addition to liquid fuel. It further details the control of fuel flow for these various fuel types.
   • Potential Anticipation under 35 U.S.C. § 102: As a parent application in the priority chain of US11143120, this patent would generally not anticipate claims in US11143120 that are fully supported by the common priority date of June 12, 2015.

4. US 10,697,379 B2

   • Full Citation: U.S. Pat. No. 10,697,379 B2, titled "Tri fuel gen".
   • Publication/Filing Date: Filed on March 20, 2019 (as U.S. patent application Ser. No. 16/358,822), claiming priority to the earlier applications, and issued on July 7, 2020.
   • Brief Description: This patent likely details a tri-fuel generator system, extending the multi-fuel capabilities to three distinct fuel sources and their associated fuel delivery and control mechanisms.
   • Potential Anticipation under 35 U.S.C. § 102: US11143120 is a continuation of this application. Therefore, for claims in US11143120 that are entitled to the common priority date of June 12, 2015, this patent would generally not serve as anticipatory prior art under 35 U.S.C. § 102.

It is important to note that a definitive assessment of anticipation under 35 U.S.C. § 102 would require a detailed claim-by-claim comparison and a thorough review of the prosecution history to determine if any claims in US11143120 contain new subject matter not entitled to the earliest priority date. In such a scenario, these parent applications could potentially act as prior art against those specific claims based on their respective filing or publication dates.

Here's an analysis of the obviousness of US patent 11143120 under 35 U.S.C. § 103, identifying combinations of prior art references and the motivation for combining them, based on the provided patent text and its listed priority documents as prior art.

For this analysis, US10221780B2 ("Dual fuel lockout switch for generator engine") and US10697398B2 ("Batteryless dual fuel engine with liquid fuel cut-off") are considered prior art as they are cited as priority documents for US11143120 and establish a relevant prior art date of 2015-06-12. These patents likely disclose the basic elements of multi-fuel engines, fuel lines, and cutoff solenoids. The "Background of the Invention" section of US11143120 itself highlights known problems in existing dual-fuel systems, which provides strong motivation for a person having ordinary skill in the art (POSA) to seek solutions. A POSA in this field would be an engineer or technician familiar with small internal combustion engines, fuel systems, and generator design.

Analysis of Independent Claim 1: Multi-Fuel Engine with Timing Circuits

Claim 1: "A multi-fuel engine comprising: an engine operable on a liquid fuel and a gaseous fuel; a carburetor attached to an intake of the engine to mix air and fuel and connect a liquid fuel source to the intake, the carburetor comprising a float bowl; a liquid cutoff solenoid coupled to open and close a liquid fuel path to the engine; a gaseous cutoff solenoid coupled to open and close a gaseous fuel source to the engine; a switch selectively coupling a power source to the liquid cutoff solenoid and the gaseous cutoff solenoid to open and close the liquid fuel path and the gaseous fuel path; and one or more timing circuits electrically coupled to the liquid cutoff solenoid and the gaseous cutoff solenoid that operate to control an actuation time of the liquid cutoff solenoid and the gaseous cutoff solenoid."

• Prior Art Combination: US10221780B2 or US10697398B2, combined with general knowledge of electronic timing circuits.
• Elements Disclosed by Prior Art (e.g., US10221780B2 or US10697398B2, or general knowledge): Multi-fuel engines (e.g., dual-fuel generators), carburetors with float bowls, liquid and gaseous fuel cutoff solenoids, and switches to select between fuel sources are all explicitly or implicitly taught as known in the background of US11143120 and would be present in the mentioned priority documents. The "Background of the Invention" states, "Certain generators are configured to operate as 'dual fuel' generators... These generators are driven by an internal combustion engine that is configured to operate on either liquid fuel or an alternative fuel" and mentions a "first fuel line for liquid fuel and a second fuel line for gaseous fuel". The patent further describes "electrical fuel switch 54 for selecting a desired fuel to the engine" and "electro-mechanical valve system 76 that includes a carburetor cutoff solenoid 94, gasoline cutoff solenoid 96, and a LPG cutoff solenoid 98".
• Distinguishing Feature of Claim 1: The inclusion of "one or more timing circuits electrically coupled to the liquid cutoff solenoid and the gaseous cutoff solenoid that operate to control an actuation time of the liquid cutoff solenoid and the gaseous cutoff solenoid."
• Motivation to Combine: The "Background of the Invention" in US11143120 clearly articulates a problem in existing dual-fuel systems: "during cross-over switching between the fuel sources the engine can experience overly rich air-fuel ratio. This is particularly problematic when switching from a liquid fuel to a gaseous fuel because carburetors have a fuel bowl containing fuel that is drawn into the engine even after the liquid fuel source is cut-off. Therefore, for a period of time, the engine is running on both liquid and gaseous fuels causing an overly rich fuel mixture. Further, such simultaneous delivery of fuel from the first fuel line and the second fuel line, even if for a brief time, may make the engine hard to start and lead to unstable operating conditions".
  A POSA would be highly motivated to solve this known problem of "overly rich air-fuel ratio" and "simultaneous delivery of fuel" during fuel changeover, which leads to "hard starting, rough running, and unstable operating conditions". Introducing timing control for the solenoids would be a logical and predictable solution to precisely manage the opening and closing sequences, thereby preventing or minimizing the undesirable fuel overlap. The use of "adjustable rheostats or predefined electronic delay circuits" for introducing time delays or adjustments in control systems is a well-known engineering technique in electromechanical applications. Therefore, modifying an existing dual-fuel engine (as disclosed in US10221780B2 or US10697398B2) with standard timing circuits to address this known problem would be obvious to a POSA.

Analysis of Independent Claim 12: Multi-Fuel Generator with Off-Board Fuel Regulator System

Claim 12: "A multi-fuel generator and fuel delivery system comprising: a multi-fuel internal combustion engine configured to operate on a liquid fuel supplied from a liquid fuel source through a liquid fuel line and a gaseous fuel supplied from a pressurized fuel source through a gaseous fuel line; an alternator driven by the multi-fuel internal combustion engine; and a fuel regulator system located off-board the generator and comprising: a primary pressure regulator coupled to a service valve of the pressurized fuel source to regulate fuel supplied from the pressurized fuel source to a reduced pressure, and a secondary pressure regulator coupled to the primary pressure regulator to regulate fuel supplied from the primary pressure regulator to a desired pressure for delivery through the gaseous fuel line to operate the engine."

• Prior Art Combination: General knowledge of multi-fuel generators, two-stage gaseous fuel regulators, and design considerations for compact and cost-effective devices.
• Elements Disclosed by Prior Art (General Knowledge): Multi-fuel generators with engines driving alternators and operating on liquid and pressurized gaseous fuels are known (e.g., as exemplified by the general context of US11143120 and its priority documents). Gaseous fuel systems typically require pressure regulation, and two-stage pressure regulators are commonly used for pressurized fuels like LPG to safely and effectively reduce fuel pressure to the engine's operating requirements. The patent states, "Fuel regulator system 56 includes a primary pressure regulator 64 coupled to pressurized fuel container 50 and a secondary pressure regulator 66".
• Distinguishing Feature of Claim 12: The "fuel regulator system located off-board the generator."
• Motivation to Combine: US11143120 explicitly states the motivation for this arrangement: "secondary pressure regulator 66 is mounted off-board the generator to reduce size and cost of the generator". Reducing the size and cost of a product, particularly a portable generator, is a fundamental and often-sought design goal in engineering. A POSA would be motivated to achieve these benefits by moving bulky or heavy components that do not require integral mounting, such as the fuel regulator system, off-board the main generator unit. This would be a routine design optimization based on known desirable outcomes. Thus, combining a known multi-fuel generator with a standard two-stage gaseous fuel regulator system and locating it off-board to achieve recognized advantages of reduced size and cost would be obvious.

Analysis of Independent Claim 18: Carburetor with Main and Idle Circuit Cutoff Solenoid

Claim 18: "A carburetor for use in a multi-fuel internal combustion engine, the carburetor comprising: a throat in which fuel and air are mixed in throat to provide an air-fuel mixture for the multi-fuel internal combustion engine; a valve located in the throat to provide a choke and throttle for the multi-fuel internal combustion engine; a float bowl to hold liquid fuel; a main fuel circuit positioned downstream from the float bowl and extending from the float bowl to the throat; an idle fuel circuit that provides a flow path to the throat downstream of the throttle to run the engine at idle; and a carburetor cutoff solenoid configured to selectively control fuel flow through the main fuel circuit and the idle fuel circuit."

• Prior Art Combination: A standard carburetor (general knowledge) used in multi-fuel engines, combined with the knowledge of the fuel overlap problem during switching.
• Elements Disclosed by Prior Art (General Knowledge): The core components of a carburetor—throat, choke/throttle valve, float bowl, main fuel circuit, and idle fuel circuit—are all standard and well-known in internal combustion engine technology. Multi-fuel engines often adapt existing carburetor designs.
• Distinguishing Feature of Claim 18: A "carburetor cutoff solenoid configured to selectively control fuel flow through the main fuel circuit and the idle fuel circuit."
• Motivation to Combine: The "Background of the Invention" of US11143120 specifically identifies the problem: "This is particularly problematic when switching from a liquid fuel to a gaseous fuel because carburetors have a fuel bowl containing fuel that is drawn into the engine even after the liquid fuel source is cut-off. Therefore, for a period of time, the engine is running on both liquid and gaseous fuels causing an overly rich fuel mixture". This problem is particularly acute with the idle fuel circuit. The patent further clarifies that while "gasoline cutoff solenoid 96 prevents drawing gasoline through the idle fuel circuit after carburetor cutoff solenoid 94 closes the main fuel circuit," a more direct solution is preferred. The patent describes that "in another embodiment of the invention, carburetor cutoff solenoid 94 is configured to control fuel flow through both main fuel circuit 152 and idle fuel circuit 158. For instance, idle fuel circuit 158 may branch off from main fuel circuit 152 with carburetor cutoff solenoid 94 actuating to block fuel flow into both circuits".
  A POSA faced with the known problem of residual liquid fuel from the float bowl (especially through the idle circuit) causing an overly rich mixture during a fuel switchover would be motivated to ensure a complete cutoff of liquid fuel from all paths within the carburetor. Modifying a standard carburetor to integrate a cutoff solenoid that effectively blocks both the main and idle fuel circuits is a straightforward and logical engineering solution to directly address and prevent this known issue.

For US patent 11143120, here's a detailed breakdown of its term adjustments, related applications, and projected expiration:

1. Patent Term Adjustment (PTA):
The provided patent information for US11143120 does not explicitly state any Patent Term Adjustment (PTA) in days. However, PTA is a system that adds time to a patent's 20-year term to compensate for certain delays by the USPTO during prosecution. These delays can include:

• Failure to issue a first Office Action or notice of allowance within 14 months of filing.
• Failure to act within four months of an applicant's response to an Office Action.
• Failure to issue the patent within four months of payment of the issue fee.
• Failure to issue a patent within three years of the actual filing date (excluding applicant-caused delays).

PTA is calculated at the time the patent issues and is included in the Issue Notification Letter.

2. Patent Term Extension (PTE):
There is no indication that US11143120 has received or is eligible for Patent Term Extension (PTE). PTE is a statutory remedy primarily available for patents covering human or veterinary drugs, medical devices, food additives, or color additives, to compensate for time lost during pre-market regulatory review by agencies like the FDA. This patent, relating to a fuel system for an internal combustion engine, does not fall into these categories. The maximum PTE is 5 years, and the total post-approval patent life cannot exceed 14 years from the date of FDA approval.

3. Continuation Applications:
US11143120 is explicitly identified as a continuation of and claims priority to several earlier patent applications:

• U.S. patent application Ser. No. 16/358,822, filed Mar. 20, 2019 (which issued as US10697379B2).
• U.S. patent application Ser. No. 15/285,215, filed Oct. 4, 2016 (which issued as U.S. Pat. No. 10,393,034).
• U.S. patent application Ser. No. 14/925,441, filed Oct. 28, 2015 (which issued as US10697398B2).
• U.S. patent application Ser. No. 14/738,060, filed Jun. 12, 2015 (which issued as U.S. Pat. No. 10,221,780).

The term "continuation" implies that these earlier applications share a common disclosure with US11143120, but present different claims.

4. Divisional Applications:
The patent document does not explicitly state that US11143120 is a divisional application. However, divisional applications arise when a single patent application contains more than one patentable invention, and the applicant chooses to pursue the non-elected inventions in a separate, later-filed application.

5. Related Family Members:
Based on the continuation chain, the following are related family members:

• US10697379B2 (from application Ser. No. 16/358,822)
• US10393034B2 (from application Ser. No. 15/285,215)
• US10697398B2 (from application Ser. No. 14/925,441)
• US10221780B2 (from application Ser. No. 14/738,060)

The Google Patents page also lists "Family Applications (3)" with the same priority date of 2015-06-12, reinforcing these as related family members.

6. Projected Expiration Date:
The Google Patents page explicitly states the "Anticipated expiration" date for US11143120 as 2035-06-12.

For utility patents, the patent term is generally 20 years from the earliest filing date (or priority date) of the non-provisional application. In this case, the earliest priority date claimed is June 12, 2015, from U.S. patent application Ser. No. 14/738,060. Therefore, 20 years from this date would be June 12, 2035, aligning with the "Anticipated expiration" date provided by Google Patents. This date would be subject to any PTA or PTE, but as noted, no PTE is expected, and any PTA would need to be calculated based on the prosecution history.

Defensive Disclosure Document for US11143120

Patent Title: Fuel system for a multi-fuel internal combustion engine
Patent Number: US11143120
Current Assignee: Champion Power Equipment Inc
Analysis Date: 2026-05-18

This document outlines defensive disclosures for US patent 11143120, focusing on creating prior art for potential future incremental improvements by competitors. The aim is to establish obviousness or non-novelty for variations of the core claims.

Derivations from Claim 1

Claim 1: A multi-fuel engine comprising: an engine operable on a liquid fuel and a gaseous fuel; a carburetor attached to an intake of the engine to mix air and fuel and connect a liquid fuel source to the intake, the carburetor comprising a float bowl; a liquid cutoff solenoid coupled to open and close a liquid fuel path to the engine; a gaseous cutoff solenoid coupled to open and close a gaseous fuel source to the engine; a switch selectively coupling a power source to the liquid cutoff solenoid and the gaseous cutoff solenoid to open and close the liquid fuel path and the gaseous fuel path; and one or more timing circuits electrically coupled to the liquid cutoff solenoid and the gaseous cutoff solenoid that operate to control an actuation time of the liquid cutoff solenoid and the gaseous cutoff solenoid.

---

Derivative 1.1: Material & Component Substitution - Piezoelectric Actuators for Solenoids

• Enabling Description: This derivative replaces the electromagnetic solenoids (liquid cutoff solenoid and gaseous cutoff solenoid) with high-speed piezoelectric actuators. Each piezoelectric actuator consists of a stack of piezoceramic elements (e.g., Lead Zirconate Titanate, PZT-5H) integrated with a mechanical amplifying structure (e.g., flextensional mechanism) to achieve sufficient stroke (e.g., 100-200 µm) and force (e.g., 5-10 N) for rapid valve opening/closing. The timing circuits are adapted to provide precise, high-voltage (e.g., 0-150V) control signals to the piezoelectric elements, leveraging their microsecond-level response times for ultra-fast and precise fuel flow modulation, minimizing overlap during "on-the-fly" fuel switching. The valve seats would be fabricated from wear-resistant ceramics (e.g., alumina or silicon nitride) to withstand frequent, high-impact actuation cycles.
• Mermaid Diagram:

  flowchart TD
      PS[Power Source] --> S[Switch]
      S -- Control Signal --> TC[Timing Circuit - Piezo Driver]
      TC -- High Voltage Pulse --> PA_L[Piezo Actuator Liquid]
      TC -- High Voltage Pulse --> PA_G[Piezo Actuator Gaseous]
      PA_L -- Actuates Valve --> LFP[Liquid Fuel Path]
      PA_G -- Actuates Valve --> GFP[Gaseous Fuel Path]
      LFP --> Carb[Carburetor with Float Bowl]
      GFP --> Carb
      Carb --> Engine[Multi-Fuel Engine]
  

---

Derivative 1.2: Operational Parameter Expansion - Micro-Scale Fuel Delivery System for Portable Power

• Enabling Description: This variation scales down the multi-fuel engine system for micro-power generation, such as for advanced portable electronics or miniature drones. The engine is a micro-internal combustion engine (e.g., 1-5 cc displacement). The carburetor is a micro-carburetor fabricated using MEMS (Micro-Electro-Mechanical Systems) techniques, featuring etched fluidic channels and a micro-float bowl. Liquid and gaseous fuel cutoff is managed by micro-solenoid valves or micro-piezoelectric valves, specifically designed for ultra-low flow rates (e.g., 10-100 µL/min for liquid fuel, 1-10 mL/min for gaseous fuel). The timing circuits are integrated into a System-on-Chip (SoC) using low-power CMOS technology, enabling precise fuel switching within milliseconds, crucial for maintaining stable power output in rapidly changing load conditions characteristic of portable devices. Fuel pressures are scaled appropriately, with liquid fuel delivered by a micro-pump and gaseous fuel regulated by a micro-pressure sensor and valve assembly.
• Mermaid Diagram:

  graph TD
      MP[Micro-Power Source] --> MS[Micro-Switch]
      MS -- Control --> SoC[SoC - Timing & Control]
      SoC -- Actuation Signal --> MV_L[Micro Valve Liquid]
      SoC -- Actuation Signal --> MV_G[Micro Valve Gaseous]
      MPump[Micro-Pump] -- Liquid Fuel --> MV_L
      MGasReg[Micro Gas Regulator] -- Gaseous Fuel --> MV_G
      MV_L --> MCarb[Micro-Carburetor]
      MV_G --> MCarb
      MCarb --> MEngine[Micro-ICE]
  

---

Derivative 1.3: Cross-Domain Application - Fuel System for Emergency Response Robotics

• Enabling Description: This multi-fuel system is integrated into a robotic platform for prolonged emergency response operations in hazardous environments, where primary fuel sources may be intermittent or unavailable. The engine powers the robot's locomotion and onboard systems. The liquid fuel could be a high-energy density alcohol fuel (e.g., methanol, ethanol) for sustained operations, while the gaseous fuel is a readily available, safely stored alternative (e.g., compressed hydrogen, natural gas from localized extraction points). The carburetor is hardened for extreme temperatures (-40°C to 80°C) and vibration, with solenoids rated for intrinsic safety in explosive atmospheres (ATEX certified). The timing circuits are designed with redundancy and fault tolerance, using radiation-hardened components for deployment in radioactively contaminated zones. The switch supports remote control and autonomous fuel selection based on sensor inputs (e.g., fuel level, environmental gas composition, mission profile).
• Mermaid Diagram:

  graph TD
      SubGraph FuelSystem
          direction LR
          LFS[Liquid Fuel Source (Alcohol)] -- Liquid Fuel Line --> LCS[Liquid Cutoff Solenoid]
          GFS[Gaseous Fuel Source (H2/NG)] -- Gaseous Fuel Line --> GCS[Gaseous Cutoff Solenoid]
          LCS --> Carb[Hardened Carburetor]
          GCS --> Carb
      end
  
      PS[Robotic Power Source] --> FC[Fault-Tolerant Controller]
      FC -- Control Signal --> LCS
      FC -- Control Signal --> GCS
      FC -- Control Signal --> TC[Redundant Timing Circuits]
      TC -- Timing --> LCS
      TC -- Timing --> GCS
      Carb --> Engine[Robotic Engine (ICE)]
      Engine --> RobotSys[Robot Systems & Locomotion]
      EnvSens[Environmental Sensors] -- Data --> FC
      RC[Remote Control] -- Commands --> FC
  

---

Derivative 1.4: Integration with Emerging Tech - AI-Optimized Predictive Fuel Switching

• Enabling Description: The multi-fuel engine system incorporates an AI-driven optimization module for predictive fuel switching. IoT sensors (e.g., fuel level, engine load, exhaust emissions, ambient temperature, fuel quality via spectroscopic analysis) provide real-time data to an edge computing unit. A machine learning model, trained on historical engine performance data, environmental conditions, and fuel cost/availability, predicts optimal fuel switching points to maximize efficiency, minimize emissions, or extend engine life. The timing circuits are dynamically adjusted by the AI controller to implement precise fuel changeovers, potentially introducing micro-delays or overlaps based on real-time engine state. Blockchain technology is used to record fuel consumption, quality, and supply chain provenance, ensuring verifiable data for regulatory compliance and automated fuel ordering. The switch can be overridden manually but defaults to AI-driven control.
• Mermaid Diagram:

  graph TD
      SubGraph FuelSystem
          LFS[Liquid Fuel Source] --> LCS[Liquid Cutoff Solenoid]
          GFS[Gaseous Fuel Source] --> GCS[Gaseous Cutoff Solenoid]
          LCS --> Carb[Carburetor]
          GCS --> Carb
      end
  
      Carb --> Engine[Multi-Fuel Engine]
      Engine --> Alt[Alternator]
      Alt --> PS[Power Source]
  
      Sensors[IoT Sensors (Fuel Level, Load, Emissions, Temp, Quality)] --> EdgeComp[Edge Computing Unit]
      EdgeComp -- Real-time Data --> AIM[AI Optimization Module]
      AIM -- Predictive Control --> TC[Dynamic Timing Circuits]
      TC -- Actuation Commands --> LCS
      TC -- Actuation Commands --> GCS
      AIM -- Blockchain Transactions --> BC[Blockchain Ledger]
      BC -- Verifiable Data --> SC[Supply Chain Management]
      ManInput[Manual Override Switch] -- Input --> AIM
  

---

Derivative 1.5: The "Inverse" or Failure Mode - Safe-Shutdown Fuel System

• Enabling Description: This system is designed for a safe-shutdown mode, where in the event of a critical system malfunction (e.g., loss of power, severe engine overheat, detected fuel leak, or control system failure), all fuel flow to the engine is immediately and reliably cut off. The liquid and gaseous cutoff solenoids are "fail-safe closed" types, requiring continuous power to remain open. The timing circuits include a watchdog timer that, upon detecting a control signal absence or anomaly, de-energizes all solenoids, causing them to default to the closed position. The float bowl is equipped with a passive drain valve that opens upon loss of power, allowing residual liquid fuel to drain into a fire-resistant containment sump, preventing an overly rich condition or fire hazard. Gaseous fuel lines incorporate thermally activated cutoff valves that trigger if exposed to high temperatures, in addition to the electrically controlled solenoid.
• Mermaid Diagram:

  stateDiagram-v2
      [*] --> Idle : System Start
      Idle --> Liquid_Mode : Switch to Liquid
      Idle --> Gaseous_Mode : Switch to Gaseous
  
      Liquid_Mode --> Gaseous_Mode : Fuel Switch (on-the-fly)
      Gaseous_Mode --> Liquid_Mode : Fuel Switch (on-the-fly)
  
      Liquid_Mode --> Safe_Shutdown : Critical Malfunction Detected
      Gaseous_Mode --> Safe_Shutdown : Critical Malfunction Detected
      Idle --> Safe_Shutdown : Critical Malfunction Detected
  
      Safe_Shutdown --> [*] : System De-energized
  
      state Liquid_Mode {
          LCS_Open: Liquid Solenoid OPEN (Powered)
          GCS_Closed: Gaseous Solenoid CLOSED (Unpowered)
      }
      state Gaseous_Mode {
          LCS_Closed: Liquid Solenoid CLOSED (Unpowered)
          GCS_Open: Gaseous Solenoid OPEN (Powered)
      }
      state Safe_Shutdown {
          All_Solenoids_Closed: All Solenoids FAIL-SAFE CLOSED (Unpowered)
          Float_Bowl_Drained: Float Bowl Passive Drain OPEN
          Therm_Valves_Closed: Thermal Cutoff Valves CLOSED
      }
  

---

Derivations from Claim 12

Claim 12: A multi-fuel generator and fuel delivery system comprising: a multi-fuel internal combustion engine configured to operate on a liquid fuel supplied from a liquid fuel source through a liquid fuel line and a gaseous fuel supplied from a pressurized fuel source through a gaseous fuel line; an alternator driven by the multi-fuel internal combustion engine; and a fuel regulator system comprising: a primary pressure regulator coupled to a service valve of the pressurized fuel source to regulate fuel supplied from the pressurized fuel source to a reduced pressure, and a secondary pressure regulator coupled to the primary pressure regulator to regulate fuel supplied from the primary pressure regulator to a desired pressure for delivery through the gaseous fuel line to operate the engine.

---

Derivative 12.1: Material & Component Substitution - High-Performance Composites for Regulators and Lines

• Enabling Description: The fuel regulator system, including the primary and secondary pressure regulators and the gaseous fuel lines, is constructed using advanced high-performance composite materials. Regulator bodies are fabricated from carbon fiber reinforced polymer (CFRP) with a high-density polyethylene (HDPE) liner for chemical resistance, significantly reducing weight and improving corrosion resistance compared to traditional brass or aluminum. Diaphragms in the regulators are made from advanced elastomers like Perfluoroelastomer (FFKM) for enhanced chemical compatibility and thermal stability across a wider operating range. Gaseous fuel lines are replaced with multi-layer composite hoses (e.g., polyamide inner, aramid fiber braid, polyurethane outer) to tolerate higher pressures and reduce permeation, offering a lighter and more durable alternative to rubber or metal hoses, especially for high-pressure natural gas or hydrogen applications.
• Mermaid Diagram:

  graph TD
      PFS[Pressurized Fuel Source] -- Service Valve --> PPR[Primary Pressure Regulator (CFRP/FFKM)]
      PPR -- Reduced Pressure Gaseous Fuel --> SPR[Secondary Pressure Regulator (CFRP/FFKM)]
      SPR -- Desired Pressure Gaseous Fuel --> GFL[Composite Gaseous Fuel Line]
      GFL --> Engine[Multi-Fuel ICE]
      LFS[Liquid Fuel Source] --> LFL[Liquid Fuel Line]
      LFL --> Engine
      Engine --> Alt[Alternator]
      Alt --> GenOut[Generator Output]
  

---

Derivative 12.2: Operational Parameter Expansion - Cryogenic Fuel System for Extreme Cold Environments

• Enabling Description: This derivative adapts the multi-fuel generator and fuel delivery system for operation in extreme cryogenic environments (e.g., Arctic exploration, space applications, or very low-temperature industrial processes). The gaseous fuel source utilizes cryogenically stored fuels like Liquid Natural Gas (LNG) or Liquid Hydrogen (LH2). The fuel regulator system is housed within a cryo-jacketed enclosure, maintaining operating temperatures for components. The primary pressure regulator incorporates a multi-stage expander/vaporizer unit to convert the cryogenic liquid to a gaseous state while simultaneously reducing pressure. The secondary regulator then finely adjusts the warmed gaseous fuel. Fuel lines are vacuum-jacketed (e.g., super-insulated flexible lines) to prevent heat ingress and maintain cryogenic temperatures for the liquid phase before vaporization. All seals, valves, and electrical components are rated for cryogenic service (e.g., using PTFE, Kalrez, and specialized low-temperature alloys).
• Mermaid Diagram:

  flowchart TD
      CFS[Cryogenic Fuel Source (LNG/LH2)] -- Cryo Line --> SV[Service Valve]
      SV --> CJE[Cryo-Jacketed Enclosure]
      CJE -- Cryo Temp --> MPR[Multi-stage Vaporizer/PPR]
      MPR -- Warmed Gaseous Fuel --> SPR[Secondary Pressure Regulator]
      SPR -- Regulated Gaseous Fuel --> JGFL[Jacketed Gaseous Fuel Line]
      JGFL --> Engine[Multi-Fuel ICE (Cold-Start Optimized)]
      LFS[Liquid Fuel Source (Anti-Freeze Additive)] -- Insulated Line --> Engine
      Engine --> Alt[Alternator]
      Alt --> GenOut[Generator Output]
  

---

Derivative 12.3: Cross-Domain Application - Maritime Auxiliary Power Unit (APU)

• Enabling Description: This multi-fuel generator system functions as an Auxiliary Power Unit (APU) for maritime vessels, providing electricity while at anchor or for emergency power. The liquid fuel is marine diesel (MGO), and the gaseous fuel is shore-supplied LNG or onboard-generated biogas from waste. The fuel regulator system is designed for a corrosive saltwater environment, with all external components made from marine-grade stainless steel (e.g., 316L) or protected with specialized coatings (e.g., ceramic-epoxy). The primary and secondary regulators are enclosed in explosion-proof housings compliant with maritime safety regulations (e.g., SOLAS, DNV-GL). The fuel lines feature robust anti-corrosion fittings and vibration dampeners suitable for shipboard applications. The entire system is mounted on a shock-absorbing platform to mitigate engine vibrations and ship movements.
• Mermaid Diagram:

  graph TD
      LFS[Marine Diesel Tank] -- Diesel Line --> Engine[Maritime ICE]
      GFS[LNG/Biogas Source (Shore/Onboard)] -- Gaseous Line --> FRS[Marine-Grade Fuel Regulator System]
      FRS -- Regulated Gas --> Engine
      Engine --> Alt[Ship Alternator]
      Alt --> Switchboard[Vessel Switchboard]
      FRS -- Housing --> EXPH[Explosion-Proof Housing]
      FRS -- Materials --> SS[Stainless Steel 316L]
  

---

Derivative 12.4: Integration with Emerging Tech - Decentralized Microgrid Management

• Enabling Description: The multi-fuel generator's fuel delivery system is integrated into a decentralized microgrid for optimized energy generation and resource management. The fuel regulator system incorporates smart pressure sensors and flow meters with IoT connectivity, continuously monitoring fuel consumption and remaining capacity for both liquid and gaseous fuels. This data is fed into a microgrid controller that uses AI algorithms to predict demand, optimize fuel mix based on cost and environmental impact (e.g., prioritizing cleaner gaseous fuel during peak hours or when solar/wind generation is low), and trigger automated reordering of fuel. Blockchain is used to record energy generation, fuel transactions, and carbon credits within the microgrid, enabling transparent peer-to-peer energy trading and automated compliance reporting. The generator can autonomously switch fuel types based on microgrid commands.
• Mermaid Diagram:

  graph TD
      subgraph Multi-Fuel Generator Unit
          Engine[Multi-Fuel ICE] --> Alt[Alternator]
          Alt --> MG_Bus[Microgrid Bus]
          LFS[Liquid Fuel Source] --> LFL[Liquid Fuel Line] --> Engine
          PFS[Pressurized Gaseous Fuel Source] --> FRS_Smart[Smart Fuel Regulator System]
          FRS_Smart --> GFL[Gaseous Fuel Line] --> Engine
      end
  
      FRS_Smart -- IoT Data (Pressure, Flow, Levels) --> MQTT_Broker[MQTT Broker]
      MQTT_Broker -- Data Stream --> Microgrid_Controller[AI Microgrid Controller]
      Microgrid_Controller -- Commands --> FRS_Smart
      Microgrid_Controller -- Commands --> Engine_ECU[Engine ECU]
  
      Microgrid_Controller -- Blockchain Transactions --> BC_Ledger[Blockchain Ledger]
      BC_Ledger -- Smart Contracts --> Energy_Trading[Peer-to-Peer Energy Trading]
      Microgrid_Controller -- Predictions --> Auto_Fuel_Order[Automated Fuel Ordering]
      Renewables[Solar/Wind Generation] --> MG_Bus
  

---

Derivative 12.5: The "Inverse" or Failure Mode - Limited-Functionality Redundant Regulator

• Enabling Description: In this derivative, the fuel regulator system includes a "limited-functionality redundant regulator" (LFRR) designed to provide basic fuel delivery in case of primary and/or secondary regulator failure. The LFRR is a mechanically simpler, spring-loaded diaphragm regulator set to deliver gaseous fuel at a fixed, slightly lower than optimal, but still engine-operable pressure (e.g., 80% of nominal). It bypasses the primary and secondary regulators if a significant pressure drop (below a safe threshold) or complete flow cessation is detected in the main path. The LFRR is constructed with highly durable, passive components to ensure long-term readiness without requiring electrical power for its basic operation. While operating in LFRR mode, the generator might experience reduced power output or slightly higher emissions, but it maintains essential functionality for critical loads, indicated by a "Degraded Mode" signal.
• Mermaid Diagram:

  graph TD
      PFS[Pressurized Fuel Source] -- Service Valve --> Diverter[Pressure/Flow Diverter Valve]
      Diverter -- Normal Pressure --> PPR[Primary Pressure Regulator]
      PPR --> SPR[Secondary Pressure Regulator]
      SPR -- Regulated Gas --> GFL[Gaseous Fuel Line]
      GFL --> Engine[Multi-Fuel ICE]
  
      Diverter -- Low Pressure/No Flow Detected --> LFRR[Limited-Functionality Redundant Regulator]
      LFRR -- Fixed Low Pressure Gas --> Bypass_GFL[Bypass Gaseous Fuel Line]
      Bypass_GFL --> Engine
  
      PPR -- Failure Detected --> Diverter
      SPR -- Failure Detected --> Diverter
  
      LFRR -- Status Signal --> Controller[System Controller]
      Controller -- "Degraded Mode" Alert --> Operator[Operator Interface]
  

---

Derivations from Claim 18

Claim 18: A carburetor for use in a multi-fuel internal combustion engine, the carburetor comprising: a throat in which fuel and air are mixed in throat to provide an air-fuel mixture for the multi-fuel internal combustion engine; a valve located in the throat to provide a choke and throttle for the multi-fuel internal combustion engine; a float bowl to hold liquid fuel; a main fuel circuit positioned downstream from the float bowl and extending from the float bowl to the throat; an idle fuel circuit that provides a flow path to the throat downstream of the throttle to run the engine at idle; and a carburetor cutoff solenoid configured to selectively control fuel flow through the main fuel circuit and the idle fuel circuit.

---

Derivative 18.1: Material & Component Substitution - Ultrasonic Atomizer & MEMS Valves

• Enabling Description: This carburetor derivative replaces conventional fuel metering with an ultrasonic atomization system for liquid fuel and MEMS-based flow control valves for both liquid and gaseous fuels. Instead of a float bowl and conventional jets, liquid fuel is delivered to an ultrasonic atomizer embedded in the throat, which creates a fine mist, improving atomization efficiency. MEMS valves, fabricated from silicon or ceramic, replace the carburetor cutoff solenoid. These microvalves precisely control the flow rate through both the main fuel circuit (now micro-channels) and the idle fuel circuit, offering much finer resolution and faster response times than a mechanical solenoid. The throat itself is constructed from a ceramic composite (e.g., Alumina-SiC matrix) for improved wear resistance, thermal stability, and reduced friction coefficient for airflow.
• Mermaid Diagram:

  graph TD
      LFS[Liquid Fuel Source] --> MFMC[MEMS Flow Controller - Liquid]
      GFC[Gaseous Fuel Source] --> MFMC_G[MEMS Flow Controller - Gaseous]
      MFMC -- Metered Liquid --> UA[Ultrasonic Atomizer]
      UA --> Throat[Throat (Ceramic Composite)]
      MFMC_G -- Metered Gas --> Throat
      V[Choke & Throttle Valve] --> Throat
      Throat --> Engine[Multi-Fuel ICE]
      Ctrl[Control Unit] -- Signals --> MFMC
      Ctrl -- Signals --> MFMC_G
      Ctrl -- Signals --> V
  

---

Derivative 18.2: Operational Parameter Expansion - High-Altitude/Low-Pressure Carburetion

• Enabling Description: This carburetor is optimized for multi-fuel engines operating at extreme high altitudes (e.g., 10,000+ ft / 3,000+ meters) where ambient air pressure is significantly reduced. The float bowl is sealed and vented to a pressure compensation chamber that dynamically adjusts to ambient pressure, preventing fuel boiling and maintaining accurate float level. The main and idle fuel circuits feature automatically adjustable jets, controlled by a barometric pressure sensor and a micro-stepper motor, to lean the air-fuel mixture in response to lower air density. The choke mechanism is adapted for higher-altitude starting, potentially with an electronically controlled supplementary air intake to prevent over-rich conditions. The carburetor cutoff solenoid is designed with a vacuum assist mechanism to ensure reliable closure even against reduced intake vacuum.
• Mermaid Diagram:

  graph TD
      AP_Sens[Barometric Pressure Sensor] --> ECU[Engine Control Unit]
      ECU -- Adjustment Signal --> AJ_Main[Adjustable Jet - Main Fuel]
      ECU -- Adjustment Signal --> AJ_Idle[Adjustable Jet - Idle Fuel]
      LFS[Liquid Fuel Source] --> FB[Sealed Float Bowl with Pressure Comp.]
      FB --> AJ_Main
      FB --> AJ_Idle
      AJ_Main --> Throat[Carburetor Throat]
      AJ_Idle --> Throat
      GFI[Gaseous Fuel Inlet] --> Throat
      V[Choke & Throttle Valve] --> Throat
      Throat --> Engine[Multi-Fuel ICE (High Altitude)]
      ECU -- Control --> CCS[Carburetor Cutoff Solenoid (Vacuum Assist)]
      LFS --> CCS
  

---

Derivative 18.3: Cross-Domain Application - Bio-Reactant Mixing for Bioreactors

• Enabling Description: The carburetor design is re-purposed as a precision bio-reactant mixing chamber for industrial bioreactors, replacing fuel and air with liquid nutrient solutions and gaseous reagents (e.g., oxygen, CO2, nitrogen). The "throat" becomes the primary mixing zone for precise gas-liquid mass transfer. The "float bowl" holds a primary liquid nutrient, with the "main fuel circuit" and "idle fuel circuit" replaced by controlled microfluidic channels delivering specific liquid additives. The "carburetor cutoff solenoid" is re-engineered as a precision flow control valve for the liquid nutrient and other liquid reactants, enabling rapid and accurate dosing. The "choke and throttle valve" functions as a gas flow regulator and agitator within the mixing chamber, optimizing the dissolution and distribution of gaseous reactants for microbial growth or chemical synthesis.
• Mermaid Diagram:

  graph TD
      LNR[Liquid Nutrient Reservoir] -- Liquid Nutrient --> FCV_LN[Flow Control Valve - Liquid Nutrient]
      LAR1[Liquid Additive Reservoir 1] -- Liquid Additive 1 --> MFC1[Microfluidic Channel 1]
      LAR2[Liquid Additive Reservoir 2] -- Liquid Additive 2 --> MFC2[Microfluidic Channel 2]
  
      FCV_LN --> MixingZone[Bioreactor Mixing Zone (Throat)]
      MFC1 --> MixingZone
      MFC2 --> MixingZone
  
      GRS[Gaseous Reagent Source (O2, CO2)] -- Gaseous Reagent --> GFR[Gas Flow Regulator & Agitator (Choke/Throttle)]
      GFR --> MixingZone
  
      MixingZone --> Bioreactor[Bioreactor Vessel]
      Controller[Bioreactor Control System] -- Signals --> FCV_LN
      Controller -- Signals --> GFR
  

---

Derivative 18.4: Integration with Emerging Tech - Self-Calibrating Smart Carburetor

• Enabling Description: This carburetor integrates advanced sensors and an embedded microcontroller for self-calibration and adaptive control. The throat includes wide-band oxygen sensors (lambda sensors), temperature sensors, and pressure transducers. The carburetor cutoff solenoid is replaced by a smart, electronically modulated valve (e.g., a voice coil actuator or stepper motor driven pintle valve) for both main and idle circuits. An embedded AI algorithm (e.g., a PID controller with fuzzy logic or neural network adaptation) continuously analyzes real-time sensor data from the exhaust and intake, adjusting fuel metering for optimal combustion efficiency, emissions compliance, and power output, adapting to varying fuel quality or engine wear. This eliminates the need for manual jet changes. Firmware updates for fuel maps can be delivered via wireless IoT connectivity.
• Mermaid Diagram:

  graph TD
      LFS[Liquid Fuel Source] --> EMV_L[Electronically Modulated Valve - Liquid]
      GFI[Gaseous Fuel Inlet] --> Throat[Smart Carburetor Throat]
      EMV_L --> Throat
  
      Throat --> V[Choke & Throttle Valve]
      V --> Engine[Multi-Fuel ICE]
  
      Sensors[O2, Temp, Pressure Sensors] --> Microcontroller[Embedded Microcontroller with AI Algo]
      Microcontroller -- Adaptive Control Signals --> EMV_L
      Microcontroller -- Adaptive Control Signals --> V
      Microcontroller -- Telemetry/Updates --> IoT_Gateway[IoT Gateway (Wireless)]
      IoT_Gateway --> Cloud[Cloud Analytics/Firmware Updates]
  

---

Derivative 18.5: The "Inverse" or Failure Mode - Minimal-Flow Safety Carburetor

• Enabling Description: This carburetor is designed with a "minimal-flow safety mode" activated upon detection of critical faults (e.g., a stuck-open main fuel valve, severe engine overspeed, or catastrophic sensor failure). The carburetor cutoff solenoid (or an integrated safety valve) is specifically designed with a redundant, passive mechanism (e.g., a calibrated orifice plate or a pressure-activated diaphragm) that, when the main solenoid fails or power is lost, allows only a severely restricted, "limp-home" flow rate of liquid fuel. This minimal flow is sufficient to keep the engine barely running at a very low RPM for a limited time (e.g., to move the generator out of a dangerous area) but prevents high power output or runaway conditions. The idle fuel circuit is either completely shut off in this mode or also restricted to a bare minimum. Gaseous fuel is entirely shut off by its dedicated (and separate) solenoid in this failure state.
• Mermaid Diagram:

  stateDiagram-v2
      [*] --> Normal_Operation : Carburetor Init
      Normal_Operation --> Fault_Detected : Critical Fault Occurs
      Fault_Detected --> Minimal_Flow_Safety_Mode : Activate Safety Protocol
  
      state Normal_Operation {
          CCS_Control: Carburetor Cutoff Solenoid (Main & Idle Control)
          Full_Fuel_Flow: Main & Idle Circuits Active
      }
  
      state Minimal_Flow_Safety_Mode {
          CCS_Fail_Safe: Carburetor Cutoff Solenoid (Redundant/Passive)
          Restricted_Liquid_Flow: Calibrated Orifice / Low Flow Diaphragm
          Gaseous_Fuel_OFF: Gaseous Fuel Solenoid Closed
          Engine_Limp_Home: Engine operates at minimal RPM
      }
  
      Minimal_Flow_Safety_Mode --> Shutdown : Manual Shutdown / Fuel Depletion
      Shutdown --> [*]
  

---

Combination Prior Art Scenarios

Here are at least 3 "Combination Prior Art" scenarios where US11143120 is combined with existing open-source standards to demonstrate obviousness or non-novelty for future incremental improvements.

1. US11143120 + SAE J1939 (CAN Bus Standard for Commercial Vehicles)

   • Description: The integration of the multi-fuel engine's fuel management system (specifically the control of solenoids and timing circuits of Claim 1, and the fuel regulator system of Claim 12) with the SAE J1939 standard for Controller Area Network (CAN) bus in commercial vehicle applications. J1939 defines communication protocols for data exchange among ECUs, including engine parameters, fuel levels, and diagnostic trouble codes. A person skilled in the art would find it obvious to implement the switch and timing circuits (Claim 1) as J1939-compliant ECUs, allowing fuel selection and timing parameters to be transmitted and received over the vehicle's existing CAN bus. This would enable the engine to seamlessly integrate into vehicle diagnostics, telematics, and fleet management systems, where fuel type could be selected or optimized by a central vehicle controller based on factors like route, payload, or fuel availability, using standardized J1939 messages (e.g., requesting fuel mode change, reporting current fuel status). The remote regulator system (Claim 12) could also report its status and pressure readings via J1939, for instance, reporting the primary and secondary regulator pressures.
   • Obviousness Argument: For any multi-fuel engine in a commercial vehicle context, the use of existing vehicle communication standards like J1939 for command and control of critical engine components, such as fuel selection and timing, would be a matter of routine engineering design to achieve interoperability and leverage established diagnostic capabilities. This combination allows for a sophisticated multi-fuel generator management without complex bespoke wiring, leveraging the existing digital backbone.

2. US11143120 + Modbus TCP (Industrial Communication Protocol)

   • Description: The multi-fuel generator's fuel delivery system (as described in Claim 12) and the carburetor's control mechanisms (Claim 18) are integrated into an industrial automation or SCADA (Supervisory Control and Data Acquisition) system using Modbus TCP. The fuel regulator system (primary and secondary regulators) would include Modbus TCP/IP-enabled sensors for real-time pressure, temperature, and flow rate monitoring of the gaseous fuel path. The carburetor cutoff solenoid (Claim 18) and other fuel solenoids (Claim 1) would be controlled via Modbus TCP commands from a Programmable Logic Controller (PLC) or Distributed Control System (DCS). This allows for remote monitoring, diagnostics, and control of the multi-fuel generator within an industrial plant or power generation facility, enabling automated fuel switching, performance tuning, and alarm management based on plant-wide operational strategies.
   • Obviousness Argument: In industrial settings, the control and monitoring of generators and their subsystems (like fuel delivery) via widely adopted open standards such as Modbus TCP is commonplace. Extending this to a multi-fuel system, where different fuel sources need selective control and monitoring, would be a straightforward application of existing industrial communication and control principles. Integrating carburetor-specific cutoff solenoids into this framework simply provides granular control over the fuel flow as part of a larger automated system.

3. US11143120 + MQTT (Message Queuing Telemetry Transport) for Remote Monitoring

   • Description: The multi-fuel engine (Claim 1) and generator (Claim 12) system are equipped with IoT sensors to monitor fuel levels, engine status, and operational parameters (RPM, load, output voltage). This data is transmitted using the lightweight MQTT protocol over cellular or satellite networks to a remote cloud-based monitoring platform. The switch and timing circuits (Claim 1) can receive MQTT messages for remote commands (e.g., "switch to LPG," "initiate liquid fuel prime"). The fuel regulator system (Claim 12) provides its pressure readings as MQTT topics. This enables global fleet management of multi-fuel generators, predictive maintenance, and remote diagnostics, particularly useful for generators deployed in remote locations for telecommunications towers, construction sites, or off-grid power.
   • Obviousness Argument: Given the prevalence of IoT and remote monitoring in modern industrial and consumer equipment, the application of a lightweight messaging protocol like MQTT for status reporting and remote command-and-control of a multi-fuel engine or generator system would be a clear and obvious engineering choice. The features of US11143120 (precise fuel switching, multiple fuel sources) directly benefit from such a remote monitoring and control paradigm to maximize uptime and efficiency in distributed deployments.