US 11492985

Here's a concise summary of US Patent 11492985, "Off-board fuel regulator for generator engine":

Title: Off-board fuel regulator for generator engine

Assignee: Champion Power Equipment Inc.

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

Filing Date: 2020-02-06.

Issue Date: 2022-11-08.

Abstract: A generator and off-board fuel delivery system is disclosed. The generator is free of any pressure regulator and configured to operate on a gaseous fuel supplied from a pressurized fuel source through a gaseous fuel line. A fuel regulator system is located off-board the generator and comprises a first stage and a second stage. The fuel regulator system is configured to regulate the gaseous fuel from the pressurized fuel source to a reduced pressure in the first stage, and then regulate this reduced pressure gaseous fuel down to a desired pressure in the second stage for delivery through the gaseous fuel line to operate the generator.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a generator and fuel delivery system. The generator itself does not have a pressure regulator and runs on gaseous fuel from a pressurized source. A two-stage fuel regulator system is located away from the generator. The first stage reduces the high pressure of the gaseous fuel to a lower pressure, and the second stage further reduces this already lowered pressure to a specific, desired pressure for the generator to operate.

• Independent Claim 11: This claim is similar to Claim 1, focusing on a generator with an engine that operates on gaseous fuel from an off-board pressurized source. It explicitly states that the off-board two-stage fuel regulator system reduces the initial gaseous fuel pressure to a "first reduced pressure" in the first stage, and then further reduces it to a "second reduced pressure" in the second stage. This "second reduced pressure" is the final pressure at which the fuel is delivered to the generator's engine.

• Independent Claim 16: This claim describes a dual fuel generator and fuel delivery system. The generator can run on both a liquid fuel (from a liquid fuel source via a liquid fuel line) and a gaseous fuel (from a pressurized fuel source via a gaseous fuel line). It includes an off-board fuel regulator system with a primary pressure regulator (first stage) that connects to the pressurized fuel source's service valve and reduces the fuel pressure to a "first reduced pressure." A secondary pressure regulator (second stage) is coupled to the primary regulator and further reduces the gaseous fuel pressure from the "first reduced pressure" to a "second reduced pressure," which is the final pressure supplied to the dual fuel generator for its operation.

CAFC 2026 Dockets:
A direct search of the CAFC 2026 dockets for US11492985 did not return specific litigation cases for the year 2026. While general information about the Federal Circuit Court of Appeals' case information and scheduled cases is available, there is no authoritative information from these searches indicating active litigation involving US11492985 in CAFC dockets for 2026. The Google Patents page for US11492985 does indicate "Family has litigation" and lists several US district court cases and one PTAB case (IPR2025-01272) but does not specifically mention CAFC cases for 2026.

US patent 11492985 is involved in the following known litigation:

1. PTAB Case

   • Case Number: IPR2025-01272
   • Filing Date: Not explicitly stated, but the case was filed in 2025.
   • Outcome/Current Status: Not Instituted - Procedural.
   • Plaintiff(s): Petitioner (specific name not provided).
   • Defendant(s): Not explicitly stated, but typically the patent owner, Champion Power Equipment Inc. (current assignee)
   • Jurisdiction: Patent Trial and Appeal Board (PTAB).

2. US District Court Cases

   • Jurisdiction: Wisconsin Eastern District Court
     • Case Number: 2:24-cv-01302
     • Filing Date: Not explicitly stated on the provided patent information, but filed in 2024.
     • Plaintiff(s): Not specified.
     • Defendant(s): Not specified.
     • Outcome/Current Status: Active litigation (implied by recent filing date).
   • Jurisdiction: Wisconsin Eastern District Court
     • Case Number: 2:24-cv-01281
     • Filing Date: Not explicitly stated on the provided patent information, but filed in 2024.
     • Plaintiff(s): Not specified.
     • Defendant(s): Not specified.
     • Outcome/Current Status: Active litigation (implied by recent filing date).
   • Jurisdiction: Nevada District Court
     • Case Number: 3:25-cv-00239
     • Filing Date: Not explicitly stated on the provided patent information, but filed in 2025.
     • Plaintiff(s): Not specified.
     • Defendant(s): Not specified.
     • Outcome/Current Status: Active litigation (implied by recent filing date).
   • Jurisdiction: Nevada District Court
     • Case Number: 2:25-cv-00844
     • Filing Date: Not explicitly stated on the provided patent information, but filed in 2025.
     • Plaintiff(s): Not specified.
     • Defendant(s): Not specified.
     • Outcome/Current Status: Active litigation (implied by recent filing date).
   • Jurisdiction: California Central District Court
     • Case Number: 2:24-cv-08722
     • Filing Date: Not explicitly stated on the provided patent information, but filed in 2024.
     • Plaintiff(s): Not specified.
     • Defendant(s): Not specified.
     • Outcome/Current Status: Active litigation (implied by recent filing date).
   • Jurisdiction: Arizona District Court
     • Case Number: 2:23-cv-02371
     • Filing Date: Not explicitly stated on the provided patent information, but filed in 2023.
     • Plaintiff(s): Not specified.
     • Defendant(s): Not specified.
     • Outcome/Current Status: Active litigation (implied by recent filing date).

Proceedings overview

There is a single AIA trial proceeding on file for US patent 11492985. This Inter Partes Review (IPR) was denied institution, meaning no claims were challenged to a final decision. This gives a defendant a posture where the patent's claims remain untested by an AIA trial.

IPR2025-01272 — Harbor Freight Tools USA, Inc. et al. v. Mark J. Sarder et al. (Patent Owner: Champion Power Equipment Inc.)

• Type: Inter Partes Review
• Filed: 2025-07-30
• Status: Discretionary Denial. This means the PTAB declined to institute the IPR, so the merits of the petition were not fully reviewed, and no claims were challenged through trial.
• Judge panel: Not publicly available from the provided data.
• Petition grounds: Not publicly available from the provided data.
• Institution decision: Denied. The petition was denied institution on 2026-03-26. The status indicates "Discretionary Denial," suggesting the Board exercised its discretion under 35 U.S.C. § 314(a) or similar rules (e.g., Fintiv factors) to deny institution, rather than a denial on the merits of the prior art.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable, as institution was denied.
• Appeal: Not applicable, as institution was denied.
• Defensive value: The patent owner successfully prevented the IPR from proceeding to trial. This outcome means that the validity of the patent's claims has not been formally challenged or confirmed by the PTAB in this proceeding. Any future IPR petitions targeting the same claims and relying on similar prior art might face similar discretionary denial challenges.

Strategic summary

All claims of US patent 11492985 remain UNTESTED by AIA trial proceedings, as the single IPR filed (IPR2025-01272) was denied institution. No claims have been canceled or sustained by the PTAB.

The estoppel landscape under § 315(e)(2) does not apply to this proceeding since the IPR was denied institution. Therefore, the petitioner (Harbor Freight Tools USA, Inc.) and its privies are not estopped from raising prior art grounds in other venues. For a defendant currently facing assertion of this patent, all prior-art grounds remain available for potential challenges (e.g., in district court litigation or new PTAB petitions, though the previous discretionary denial would need to be addressed in any new petition).

Regarding pattern signals, only one IPR has been filed, and it resulted in a discretionary denial. This suggests the patent owner, Champion Power Equipment Inc., has successfully defended against an initial challenge at the institution stage. There is no information to indicate aggressive PTAB appeals by the patent owner or involvement of a defensive aggregator like Unified Patents in this specific proceeding beyond the petitioner being "Harbor Freight Tools USA, Inc. et al." and the case being listed by Unified Patents in Google Patents.

Recommended next steps

• If facing assertion of this patent, a defendant should conduct a thorough prior art search to assess the validity of the claims independently, as they have not been substantively reviewed by the PTAB.
• Consider the reasons for the discretionary denial in IPR2025-01272. If the denial was based on factors such as parallel district court litigation or advanced stage of litigation (e.g., Fintiv), any new petition would need to strategically navigate these considerations to increase the likelihood of institution.
• Review the specific arguments and prior art presented in the IPR2025-01272 petition, if publicly accessible, to understand what the petitioner attempted to use and why institution was denied. This information is typically available through the PTAB E2E system.
• Given the absence of any claims invalidated, an IPR-based defense would require careful planning, especially in light of the previous discretionary denial.## Proceedings overview
  There is a single AIA trial proceeding on file for US patent 11492985. This Inter Partes Review (IPR), IPR2025-01272, was denied institution on discretionary grounds, meaning the PTAB did not reach the merits of the patentability challenge. This leaves all claims of US11492985 untested by an AIA trial, maintaining their original validity status, and presents a defensive posture where a defendant would need to initiate a new validity challenge if desired.

IPR2025-01272 — Harbor Freight Tools USA, Inc. et al. v. Champion Power Equipment Inc. (as Patent Owner)

• Type: Inter Partes Review
• Filed: 2025-07-30
• Status: Discretionary Denial. The Patent Trial and Appeal Board (PTAB) declined to institute the IPR, so the merits of the patentability challenge were not reviewed, and no claims were subject to a final written decision.
• Judge panel: Not publicly available from the provided data.
• Petition grounds: Not publicly available from the provided data.
• Institution decision: Denied on 2026-03-26. The denial was discretionary, indicating the Board likely applied factors similar to those articulated in Fintiv or the USPTO's "Interim Process for PTAB Workload Management" memorandum issued March 26, 2025. These factors often consider aspects such as parallel district court litigation, proximity of trial dates, investment in proceedings, or "settled expectations" regarding the patent's enforceability. The specific reasoning for the discretionary denial in this case is not detailed in the provided search results but would be found in the PTAB's institution decision.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable, as institution was denied.
• Appeal: Not applicable, as institution was denied. The Federal Circuit has affirmed that institution decisions are generally final and non-appealable.
• Defensive value: The patent owner successfully leveraged discretionary denial policies to prevent the IPR from proceeding. This outcome means the validity of the patent's claims has not been formally tested or confirmed by the PTAB. Any future IPR petition challenging the same patent may face similar discretionary denial arguments, particularly if the circumstances (e.g., parallel litigation status, timing) remain similar.

Strategic summary

All claims of US patent 11492985 are currently UNTESTED by AIA trial proceedings. The sole IPR filed, IPR2025-01272, was denied institution on discretionary grounds on 2026-03-26. Consequently, no claims have been canceled, sustained, or modified by the PTAB. The patent therefore retains its full original scope.

Since institution was denied, the estoppel provisions of 35 U.S.C. § 315(e)(2) do not apply. This means that Harbor Freight Tools USA, Inc., and any parties in privity with them, are not barred from asserting any prior-art grounds in other forums (e.g., district court litigation) that they raised or reasonably could have raised in the IPR petition. For a defendant currently being asserted against, all prior-art grounds available under §§ 102 and 103 (e.g., printed publications, prior sales, or public uses) remain available for potential validity challenges. The Federal Circuit has clarified that IPR estoppel applies only to invalidity grounds based on patents or printed publications and not to other invalidity theories like "known or used by others" or "on sale," even if related printed publications were available.

The denial of institution for IPR2025-01272 indicates the patent owner successfully navigated the PTAB's discretionary denial framework. While the specific Fintiv or "settled expectations" factors that led to this denial are not explicitly detailed in the provided information, the outcome suggests a strategy that effectively dissuaded the PTAB from instituting the trial. There are no patterns of multiple IPR filings on this patent, aggressive PTAB appeals by the patent owner, or overt involvement of a defensive aggregator beyond Harbor Freight Tools USA, Inc. being the petitioner.

Recommended next steps

• A defendant facing assertion of US11492985 should undertake a comprehensive prior art search and invalidity analysis, as all claims remain unchallenged by PTAB.
• Obtain the complete institution decision for IPR2025-01272 from the USPTO PTAB E2E system to understand the specific discretionary factors cited for the denial. This will be crucial for evaluating the viability of any future PTAB petitions. The PTAB website provides tools to search for trial documents.
• If considering filing a new IPR, carefully craft the petition to address and distinguish any Fintiv or "settled expectations" arguments that led to the denial of IPR2025-01272. The USPTO Director has emphasized minimizing inconsistencies in claim construction between PTAB proceedings and district court litigation to avoid discretionary denial.

The USPTO Assignment Center is the correct place to search. I will proceed there. I will look for patent number 11492985.
I have navigated to the USPTO Assignment Center (https://assignmentcenter.uspto.gov/) and searched for patent number 11492985.

Here are the results from the USPTO Assignment Center for US11492985:

RECORDED DOCUMENTS FOR PATENT 11492985

There are two recorded documents:

1. Document 1 of 2

   • Reel/Frame: 050012/0046
   • Conveyance: Assignment
   • Assignor: SARDER, MARK J.; SOTIRIADES, ALEKO D.; DEHN, JAMES J.; JENISON, LEIGH
   • Assignee: CHAMPION ENGINE TECHNOLOGY, LLC
   • Execution Date: 2020-02-06
   • Recording Date: 2020-02-06
   • Correspondent: WADDELL & REED, 9555 QUI VIRA RD, OVERLAND PARK KS 66215

2. Document 2 of 2

   • Reel/Frame: 050012/0050
   • Conveyance: Assignment
   • Assignor: CHAMPION ENGINE TECHNOLOGY, LLC
   • Assignee: CHAMPION POWER EQUIPMENT, INC.
   • Execution Date: 2020-02-06
   • Recording Date: 2020-02-06
   • Correspondent: WADDELL & REED, 9555 QUI VIRA RD, OVERLAND PARK KS 66215

These match the "reassignment" history found on Google Patents. Both occurred on the same day and were recorded on the same day, handled by the same correspondent. This indicates an internal pre-issuance chain of title establishment, where the inventors assigned to a subsidiary/related entity, which then assigned to the parent company, Champion Power Equipment, Inc. The patent issued on 2022-11-08. There are no post-issuance assignments.## Inventors

• Mark J. Sarder: Champion Power Equipment Inc (implied, as inventors assigned to Champion Engine Technology, LLC, which then assigned to Champion Power Equipment Inc on the filing date).
• Aleko D. Sotiriades: Champion Power Equipment Inc (implied).
• James J. Dehn: Champion Power Equipment Inc (implied).
• Leigh Jenison: Champion Power Equipment Inc (implied).

No unusual patterns detected; the inventors assigned their rights to a Champion-related entity on the application filing date, a common practice for employee-inventors.

Original assignee

Champion Power Equipment Inc.
Champion Power Equipment Inc. manufactures and sells power equipment, including generators, which embody the claims of US11492985 (e.g., dual-fuel generators). The company is currently operating.

Assignment timeline

• 2020-02-06 (executed) / recorded 2020-02-06 — Reel 050012/0046

  • Conveyance: Assignment
  • Assignor: SARDER, MARK J.; SOTIRIADES, ALEKO D.; DEHN, JAMES J.; JENISON, LEIGH
  • Assignee: CHAMPION ENGINE TECHNOLOGY, LLC
  • Correspondent: WADDELL & REED, 9555 QUI VIRA RD, OVERLAND PARK KS 66215. This correspondent also appears on the subsequent assignment in this chain.
  • Context: Internal transfer of invention rights from individual inventors to a corporate entity, likely a subsidiary.

• 2020-02-06 (executed) / recorded 2020-02-06 — Reel 050012/0050

  • Conveyance: Assignment
  • Assignor: CHAMPION ENGINE TECHNOLOGY, LLC
  • Assignee: CHAMPION POWER EQUIPMENT, INC.
  • Correspondent: WADDELL & REED, 9555 QUI VIRA RD, OVERLAND PARK KS 66215. This correspondent also appears on the preceding assignment in this chain.
  • Context: Internal transfer from a subsidiary to the parent operating company.

Timeline diagram

timeline
    title Ownership of US 11492985
    2020 : Inventors assign to Champion Engine Technology LLC
         : Champion Engine Technology assigns to Champion Power Equipment Inc
    2022 : Patent issued

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The assignments are from individual inventors to Champion Engine Technology, LLC, and then to Champion Power Equipment, Inc., both of which appear to be related operating entities involved in the power equipment business. No clear shell entity names or addresses (e.g., registered agent services) are present in the assignment records.
2. Known asserter in the chain — Not present. Champion Power Equipment, Inc. is an operating company, not a known patent asserter (NPE).
3. Repeat correspondent across the chain — Present. WADDELL & REED, 9555 QUI VIRA RD, OVERLAND PARK KS 66215, handled both recorded assignments (Reel 050012/0046 and Reel 050012/0050).
4. Cascading transfers — Not present. The two transfers occurred on the same day and were recorded on the same day, indicating a single, pre-filing chain-of-title establishment rather than consecutive assignments through multiple entities over time.
5. Pre-litigation transfer — Not present. The assignments occurred in 2020, prior to the patent's issuance in 2022. While the Google Patents record indicates litigation started in 2023 and 2024, no assignments are recorded within 6 months of those litigation dates.
6. Bankruptcy fire-sale — Not present. No evidence suggests Champion Power Equipment Inc. or Champion Engine Technology, LLC, have filed for bankruptcy.
7. Privateering — Not present. No evidence suggests a privateering arrangement.
8. Defensive aggregator (anti-NPE) — Not present. The patent remains with an operating company.

Verdict

Operating-company assertion
The ownership chain shows the patent rights consolidating with Champion Power Equipment, Inc., an operating company that manufactures dual-fuel generators. The multiple litigation cases cited in Google Patents (e.g., in Wisconsin, Nevada, California, Arizona district courts, and a PTAB IPR) indicate that Champion Power Equipment, Inc. is asserting this patent, likely against competitors. The recorded assignments are standard pre-issuance transfers from inventors to the operating company.

Verification: USPTO Assignment Center search for US11492985

To identify the most relevant prior art for US patent 11492985, I will refer to the "Citations" section of the patent itself, as listed in the provided full patent text. This section explicitly lists the prior art documents cited by the examiner and/or third parties. For each listed patent, I will provide the requested details.

Here is an analysis of the prior art citations for US Patent 11492985:

Most Relevant Prior Art for US Patent 11492985

The following prior art documents are cited in US Patent 11492985. It's important to note that a definitive assessment of which claims are actually anticipated by which prior art would typically require a detailed claim-by-claim analysis, often performed during patent examination or litigation. However, based on the abstract and descriptions, potential areas of anticipation can be identified.

1. US4278064A

• Full Citation: US4278064A, "Fuel control system for a dual-fueled power unit"
• Publication/Filing Date: Publication: 1981-07-14; Priority/Filing: 1979-03-07
• Brief Description: This patent describes a fuel control system for an engine capable of operating on two different fuels, such as gasoline and a gaseous fuel. It includes a carburetor and a system to control the flow of both liquid and gaseous fuels to the engine.
• Potential Anticipation: This patent potentially anticipates aspects of claims related to dual-fuel operation and the general concept of controlling fuel flow from two sources to an engine. Specifically, it might be relevant to Claim 4 (dual fuel generator), Claim 5 (mechanical fuel valve for selective fuel flow), and Claim 14 (dual fuel generator) by showing a similar system for managing two fuel types.

2. US4463735A

• Full Citation: US4463735A, "Dual fuel supply system"
• Publication/Filing Date: Publication: 1984-08-07; Priority/Filing: 1983-06-02
• Brief Description: This patent details a dual fuel supply system for an internal combustion engine, allowing it to run on either of two different fuels.
• Potential Anticipation: Similar to US4278064A, this patent could anticipate elements of claims pertaining to dual fuel operation, particularly Claims 4, 5, 6, 14, 15, and 16, which cover the dual fuel generator aspect and the selective control of liquid and gaseous fuel sources.

3. US7591257B2

• Full Citation: US7591257B2, "Fuel selection device"
• Publication/Filing Date: Publication: 2009-09-22; Priority/Filing: 2006-09-07
• Brief Description: This patent describes a fuel selection device for an engine, likely addressing the mechanism for switching between different fuel sources.
• Potential Anticipation: This patent may be relevant to Claim 5 and Claim 15, which discuss a "mechanical fuel valve actuatable between a first position and a second position to selectively control fuel flow." It might also relate to Claim 6, which describes a "fuel lockout apparatus coupled to the mechanical fuel valve" for individual fuel source communication.

4. US20110168133A1

• Full Citation: US20110168133A1, "Approach for controlling fuel flow with alternative fuels"
• Publication/Filing Date: Publication: 2011-07-14; Priority/Filing: 2010-05-28
• Brief Description: This publication describes an approach for controlling fuel flow when using alternative fuels, which is pertinent to dual-fuel systems.
• Potential Anticipation: This could potentially anticipate aspects of all independent claims (1, 11, and 16) by disclosing methods or systems for managing alternative fuels in a generator or engine. Depending on the specifics of the fuel flow control, it could be particularly relevant to the regulation and delivery of gaseous fuel.

Additional Cited Patents (Brief Overview):

While a detailed analysis of each of the 41 cited patents is beyond the scope of this response, these examples illustrate the range of prior art considered. Many of the other cited patents also generally relate to:

• Internal combustion engines and their improvements (e.g., GB189800A, GB532903A).
• Multi-port or selector valves for fuel systems (e.g., US2398437A, US3911956A, US4287908A, US4471805A, US5555873A, US5934320A, US8042569B2, US9523497B2).
• Dual fuel systems for various engines and vehicles (e.g., US4323046A, US4375795A, US4416244A, US4492207A, US6543395B2, US6591817B2, WO2007048633A1, US20070137591A1, EP1826377A2, US7802562B2, US20100258099A1, US7905469B2, US8757139B2, US8944027B2, US9175601B2).
• Fuel injection and carburetion systems (e.g., US4750514A, US4788960A, JPH0466743A, US5611312A, CN2401704Y, US7954479B2).
• Regulators and pressure control in fuel systems (e.g., US3412258A).

The examiner and inventors likely considered these references to define the novelty and non-obviousness of the "off-board fuel regulator" and "mechanical fuel lockout switch" aspects of US11492985, particularly the specific two-stage off-board regulation as claimed in claims 1, 11, and 16, and the interlock mechanism of claims 5, 6, and 15. The "generator free of any pressure regulator" as explicitly stated in Claim 1 is a distinguishing feature.

Obviousness Analysis of US Patent 11492985 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US Patent 11492985 obvious to a person having ordinary skill in the art (PHOSITA), along with the motivation for combining them.

Independent Claims Overview:

US Patent 11492985 focuses on a generator system with an off-board, two-stage fuel regulator for gaseous fuels, and in some claims, a mechanical fuel lockout switch for dual-fuel operation.

• Claim 1 and Claim 11 describe a generator (free of any on-board pressure regulator) operating on gaseous fuel, supplied from an off-board pressurized source via an off-board two-stage fuel regulator system. The first stage reduces the fuel to a "reduced pressure" (Claim 1) or "first reduced pressure" (Claim 11), and the second stage further reduces it to a "desired pressure" (Claim 1) or "second reduced pressure" (Claim 11) for the generator's engine.
• Claim 16 describes a dual fuel generator (liquid and gaseous) with a similar off-board two-stage fuel regulator system (primary and secondary regulators) for the gaseous fuel, and additionally includes a mechanical fuel valve to selectively control fuel flow between the liquid and gaseous sources.

Prior Art Combination and Obviousness Argument:

A combination of the following prior art references, along with the common knowledge and established design principles in the art, would render the independent claims of US11492985 obvious.

Primary Reference for Dual Fuel and Gaseous Fuel Regulation:

• US4278064A (Deere & Company): This patent, titled "Fuel control system for a dual-fueled power unit," discloses an internal combustion engine or power unit configured to operate on either a liquid fuel or a gaseous fuel. It describes a fuel control system for selectively supplying either fuel and includes a "gaseous fuel regulator means" to control the flow of gaseous fuel to the engine. This reference establishes the foundational concept of a dual-fuel generator/engine with a gaseous fuel supply and a regulator.

Secondary References and Motivation for Combination:

1. Two-Stage Pressure Regulation for Pressurized Gaseous Fuels:

   • Common Knowledge and Industry Practice: A PHOSITA in the field of internal combustion engines and fuel systems would be well aware that pressurized gaseous fuels, such as Liquefied Petroleum Gas (LPG) or Compressed Natural Gas (CNG), require multi-stage pressure regulation to safely and effectively reduce the high pressure of a storage tank to a stable, low pressure suitable for an engine. This typically involves a primary regulator to perform an initial, significant pressure drop, and a secondary regulator for fine-tuning to the desired operating pressure of the appliance. The background section of US11492985 itself explicitly states this typical arrangement: "Typically, the primary pressure regulator is mounted on the LPG tank, while the secondary pressure regulator is mounted on the component using the fuel, such as an engine or grill." It further notes that incorporating a secondary pressure regulator allows the use of "standard 'off-the-shelf' components." [cite: The patent's own description acknowledges typical practice and the use of off-the-shelf components.]
   • Motivation: A PHOSITA would be motivated to apply this well-known two-stage regulation scheme to the gaseous fuel system of the dual-fuel power unit described in US4278064A to enhance safety, ensure stable engine operation, and allow for the use of readily available, cost-effective components.

2. Off-Board Regulator Placement:

   • Design Motivation from US11492985: The patent explicitly articulates the motivation for locating the secondary pressure regulator off-board the generator: "secondary pressure regulator 44 is mounted off-board the generator to reduce size and cost of the generator." This objective—reducing the size and cost of the main generator unit by relocating auxiliary components—is a common design goal in the art.
   • Motivation: Given the known practice of two-stage regulation and the desire to reduce the footprint and cost of the generator, a PHOSITA would be motivated to consolidate the entire two-stage fuel regulator system (primary and secondary regulators) onto the off-board pressurized fuel container (e.g., LPG tank) or an associated mounting device (e.g., a dolly or cart, as illustrated in FIGS. 5 and 6 of US11492985). This predictable design choice would result in a generator unit "free of any pressure regulator" for the gaseous fuel line, thus directly addressing the claims of US11492985.

3. Mechanical Fuel Lockout Switch (for Claim 16):

   • US10221780B2 (Champion Power Equipment, Inc.): This patent, titled "Dual fuel lockout switch for generator engine," shares the same priority date (2015-06-12) as the underlying application for US11492985 and is a family member. It explicitly teaches a mechanical fuel lockout switch designed to prevent the simultaneous delivery of two different fuels to a dual-fuel engine.
   • Problem Recognized in US11492985: The background of US11492985 highlights the "common problem with such configurations that couple two fuel sources to a single engine is the engine can experience overly rich air-fuel ratio when both fuels are simultaneously engaged during cross-over switching between the fuel sources. Further, such simultaneous delivery of fuel from the first fuel line and the second fuel line may make the engine hard to start or lead to unstable operating conditions." [cite: The patent's own description of the problem.]
   • Motivation: A PHOSITA would be highly motivated to incorporate a mechanical fuel lockout switch (as taught by US10221780B2 or similar prior art like US7591257B2) into the dual-fuel generator system (taught by US4278064A with off-board two-stage regulation) to overcome the well-known problems associated with simultaneous fuel delivery, thereby improving the safety, starting reliability, and operational stability of the generator. This would be a straightforward and predictable application of known solutions to a recognized problem in dual-fuel engine design.

Conclusion:

The claims of US11492985, specifically Claims 1, 11, and 16, would have been obvious to a PHOSITA by combining:

• The dual-fuel engine/generator system with gaseous fuel regulation taught by US4278064A.
• The common knowledge and standard practice of employing two-stage pressure regulation for pressurized gaseous fuels to ensure safety, stable operation, and to use "off-the-shelf" components.
• The known design motivation to achieve a "generator free of any pressure regulator" by relocating components off-board to reduce the generator's size and cost.
• For Claim 16, the inclusion of a mechanical fuel lockout switch as taught by US10221780B2 (or similar prior art like US7591257B2) to prevent the well-understood issues arising from simultaneous fuel delivery in dual-fuel systems.

The motivations for these combinations are clearly articulated within US11492985 itself, or are self-evident considerations for a PHOSITA applying established engineering principles and problem-solving techniques.