US 6837228

U.S. Patent 6837228, titled "Fuel injector nozzle adapter," was assigned to Holley Performance Products Inc. The inventors are Oswald Baasch, Douglas Joseph Flynn, Laura Beth Rucker, and Shane Wilson. The patent was filed on November 4, 2002, and issued on January 4, 2005.

Abstract:
The patent describes a fuel injector adapter designed to supply nitrous oxide to an internal combustion engine. This nozzle features a central fuel injector passage with a central axis and an injector outlet for directing fuel from a fuel injector to the engine. Additionally, the nozzle includes one or more first auxiliary passages, which can be arranged in an annular pattern around the fuel injector passage, terminating at first outlets. It may also have one or more second auxiliary passages, similarly arranged in an annular pattern around the fuel injector passage, terminating at second outlets. These auxiliary passages are configured to deliver nitrous oxide or other combustion reactants to the engine. The nozzle is designed to be attached to an engine intake and to fit between a fuel injector and the engine without requiring substantial modifications to the engine.

Plain-language Overview of Independent Claims:

• Independent Claim 1: This claim describes a nozzle for providing combustion reactants to an internal combustion engine. It includes a fuel injector passage with a central axis and an outlet for fuel from a fuel injector. Crucially, it also features a first auxiliary passage designed to deliver a combustion reactant to the engine, with this passage terminating at a first outlet. The nozzle is configured to be installed between a fuel injector and the engine.
• Independent Claim 13: This claim describes a system for enhancing the performance of an internal combustion engine. The system comprises a fuel injector and the nozzle as described in Claim 1. The nozzle is positioned between the fuel injector and the engine intake. It also includes a supply of nitrous oxide connected to the first auxiliary passage of the nozzle.
• Independent Claim 19: This claim focuses on a method for providing combustion reactants to an internal combustion engine. The method involves installing the nozzle (as described in Claim 1) between a fuel injector and the engine, supplying fuel through the fuel injector passage, and supplying nitrous oxide through the first auxiliary passage to the engine.

Regarding CAFC 2026 dockets for patent 6837228, I do not have authoritative information about specific docket entries for this patent in 2026. The provided search results discuss general aspects of patent claims and USPTO search tools, but do not contain specific CAFC docket information for 6837228.

I have conducted a search for known litigation involving US patent 6837228 using various patent litigation search sites and general search engines, including those that cover District Courts, Supreme Court, United States Court of Federal Claims, CAFC, and ITC.

As of April 26, 2026, I have not found any known litigation cases specifically involving US patent 6837228. The search results provided general information about patent litigation search capabilities and recent patent litigation news concerning other patents, but did not list any cases for US6837228.

Proceedings overview

There is no PTAB activity on file for US patent 6837228. This means the patent has not been subjected to any AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method review), leaving all its claims untested by the PTAB. This presents a unique defensive posture for a defendant, as no claims have been invalidated or sustained through PTAB review.

Strategic summary

All claims of US6837228 are currently untested by the PTAB. There are no canceled, sustained, or unchallenged claims in the context of an AIA trial proceeding. Since no PTAB proceedings have been filed, there is no estoppel landscape under § 315(e)(2) for any potential petitioner. All prior-art grounds remain available for a new challenge. The absence of PTAB activity suggests that this patent may not have been aggressively asserted in recent years, or that any assertions did not trigger an AIA trial challenge from defendants.

Recommended next steps

There is no PTAB activity on file for US patent 6837228. If you are a defendant facing assertion of this patent, all prior art challenges and statutory grounds remain available for an AIA trial proceeding. You would be the first to test the patent's claims at the PTAB.

Inventors

• Oswald Baasch
• Douglas Joseph Flynn
• Laura Beth Rucker (also listed as Laura Beth Cornett in assignment records)
• Shane Wilson

The inventors were likely employed by Holley Performance Products Inc. at the time of filing, as indicated by the initial assignment of their interest to the company recorded on 2004-02-10 (Reel 014966/0381).

Original assignee

The original assignee named on the issued patent is Holley Performance Products Inc. They are a leading designer, marketer, and manufacturer of high-performance automotive aftermarket products, including fuel injection and nitrous oxide injection systems, which embody the claims of the patent. Holley Performance Products Inc. is currently an operating public company, trading on the New York Stock Exchange (NYSE) under the ticker HLLY. The company has undergone various ownership changes and financial restructurings, including bankruptcies in 2008 and 2009, but has since emerged and remains an active business. As of July 17, 2026, their stock price was $2.62.

Assignment timeline

• 2004-02-04 (executed) / recorded 2004-02-10 — Reel 014966/0381
  • Conveyance: Assignment of Assignors Interest
  • Assignor: BAASCH, OSWALD; CORNETT, LAURA BETH; FLYNN, DOUGLAS JOSEPH; WILSON, SHANE
  • Assignee: HOLLEY PERFORMANCE PRODUCTS
  • Correspondent: ROBERT M. SHEEHAN, ESQ.; FISH & RICHARDSON, P.C.; 225 FRANKLIN STREET; BOSTON, MA 02110
  • Context: Initial assignment from inventors to the original assignee.
• 2008-01-22 (executed) / recorded 2008-01-22 — Reel 020393/0547
  • Conveyance: Security Agreement
  • Assignor: HOLLEY PERFORMANCE PRODUCTS, INC.
  • Assignee: WELLS FARGO FOOTHILL, INC. (F/K/A FOOTHILL CAPITAL CORPORATION)
  • Correspondent: JOHN R. POSTHUMUS, ESQ.; RIDER BENNETT, LLP; 33 SOUTH SIXTH STREET, SUITE 4900; MINNEAPOLIS, MN 55402. This correspondent appears again on 2010-06-30.
  • Context: Grant of security interest by Holley Performance Products Inc.
• 2010-06-30 (executed) / recorded 2010-06-30 — Reel 025114/0831
  • Conveyance: Security Agreement
  • Assignor: HOLLEY PERFORMANCE PRODUCTS INC.
  • Assignee: WILMINGTON TRUST FSB
  • Correspondent: JOHN R. POSTHUMUS, ESQ.; RIDER BENNETT, LLP; 33 SOUTH SIXTH STREET, SUITE 4900; MINNEAPOLIS, MN 55402. This correspondent appeared previously on 2008-01-22.
  • Context: Grant of security interest by Holley Performance Products Inc.
• 2012-06-05 (executed) / recorded 2012-06-05 — Reel 028399/0989
  • Conveyance: Corrective Assignment
  • Assignor: BAASCH, OSWALD; CORNETT, LAURA BETH; FLYNN, DOUGLAS JOSEPH; WILSON, SHANE
  • Assignee: HOLLEY PERFORMANCE PRODUCTS, INC.
  • Correspondent: STEVEN D. MYERS; HOLLAND & HART LLP; P.O. BOX 8749; DENVER, CO 80201
  • Context: Corrective assignment to refine the assignee's legal name.
• 2012-06-08 (executed) / recorded 2012-06-08 — Reel 028448/0107
  • Conveyance: Security Agreement
  • Assignor: HOLLEY PERFORMANCE PRODUCTS INC.
  • Assignee: LBC CREDIT PARTNERS II, L.P., AS AGENT
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Grant of security interest by Holley Performance Products Inc.
• 2012-06-08 (executed) / recorded 2012-06-08 — Reel 028448/0122
  • Conveyance: Security Agreement
  • Assignor: HOLLEY PERFORMANCE PRODUCTS INC.
  • Assignee: WELLS FARGO CAPITAL FINANCE, INC.
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Grant of security interest by Holley Performance Products Inc.
• 2012-06-10 (executed) / recorded 2012-06-19 — Reel 028522/0762
  • Conveyance: Release of Security Interest
  • Assignor: WELLS FARGO CAPITAL FINANCE, INC. (F/K/A WELLS FARGO FOOTHILL, INC.)
  • Assignee: HOLLEY PERFORMANCE PRODUCTS, INC.
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Release of security interest held by Wells Fargo.
• 2012-06-16 (executed) / recorded 2012-06-16 — Reel 028489/0904
  • Conveyance: Termination and Release of Security Interest in Intellectual Property Rights
  • Assignor: WILMINGTON TRUST, NATIONAL ASSOCIATION, AS SUCCESSOR-BY-MERGER TO WILMINGTON TRUST FSB
  • Assignee: HOLLEY PERFORMANCE PRODUCTS, INC.; DEMON FUEL SYSTEMS, INC.; SNIPER MOTORSPORTS, INC.
  • Correspondent: KEVIN B. KEALEY; BARNES & THORNBURG LLP; 11 SOUTH MERIDIAN STREET; INDIANAPOLIS, IN 46204
  • Context: Release of security interest held by Wilmington Trust.
• 2012-06-29 (executed) / recorded 2012-06-29 — Reel 028585/0746
  • Conveyance: Security Agreement
  • Assignor: HOLLEY PERFORMANCE PRODUCTS INC.
  • Assignee: HAWTHORN FINCO, LLC
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Grant of security interest by Holley Performance Products Inc.
• 2013-10-25 (executed) / recorded 2013-10-25 — Reel 030701/0150
  • Conveyance: Security Agreement
  • Assignor: DEMON FUEL SYSTEMS, INC.; HOLLEY PERFORMANCE PRODUCTS INC.; HOLLEY PERFORMANCE SYSTEMS, INC.; QFT HOLDINGS, INC.
  • Assignee: GENERAL ELECTRIC CAPITAL CORPORATION, AS AGENT
  • Correspondent: BRIAN T. BLUMENSTEIN; HOLLAND & HART LLP; P.O. BOX 8749; DENVER, CO 80201. This correspondent appears again on 2015-09-24.
  • Context: Grant of security interest by Holley and related entities.
• 2013-10-30 (executed) / recorded 2013-10-30 — Reel 030706/0009
  • Conveyance: Release By Secured Party
  • Assignor: LBC CREDIT PARTNERS II, L.P.
  • Assignee: HOLLEY PERFORMANCE PRODUCTS INC.
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Release of security interest by LBC Credit Partners.
• 2013-10-30 (executed) / recorded 2013-10-30 — Reel 030706/0023
  • Conveyance: Release By Secured Party
  • Assignor: HAWTHORN FINCO, LLC
  • Assignee: HOLLEY PERFORMANCE PRODUCTS INC.
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Release of security interest by Hawthorn Finco, LLC.
• 2013-10-30 (executed) / recorded 2013-10-30 — Reel 030706/0038
  • Conveyance: Release By Secured Party
  • Assignor: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS AGENT
  • Assignee: HOLLEY PERFORMANCE PRODUCTS INC.
  • Correspondent: TRACY L. ELDRIDGE, ESQ.; SHEPPARD MULLIN RICHTER & HAMPTON LLP; 333 SOUTH HOPE STREET, 43RD FLOOR; LOS ANGELES, CA 90071. This correspondent recurs multiple times on security agreements and releases for Holley Performance Products Inc.
  • Context: Release of security interest by Wells Fargo Bank.
• 2015-09-22 (executed) / recorded 2015-09-22 — Reel 035235/0675
  • Conveyance: Patent Security Agreement
  • Assignor: ACCEL PERFORMANCE GROUP LLC; HOLLEY PERFORMANCE PRODUCTS INC.; HOLLEY PERFORMANCE SYSTEMS, INC.; MSD LLC; POWERTEQ LLC; QFT HOLDINGS, INC.
  • Assignee: CERBERUS BUSINESS FINANCE, LLC, AS COLLATERAL AGENT
  • Correspondent: BENJAMIN F. LADD; MCGUIREWOODS LLP; 201 NORTH TRYON STREET, SUITE 3000; CHARLOTTE, NC 28202
  • Context: Grant of security interest by Holley and related entities.
• 2015-09-24 (executed) / recorded 2015-09-24 — Reel 035252/0569
  • Conveyance: Release of Security Interest in Patent Collateral
  • Assignor: GENERAL ELECTRIC CAPITAL CORPORATION
  • Assignee: DEMON FUEL SYSTEMS, INC.; HOLLEY PERFORMANCE PRODUCTS INC.; QFT HOLDINGS, INC.; HOLLEY PERFORMANCE SYSTEMS, INC.
  • Correspondent: BRIAN T. BLUMENSTEIN; HOLLAND & HART LLP; P.O. BOX 8749; DENVER, CO 80201. This correspondent appeared previously on 2013-10-25.
  • Context: Release of security interest by General Electric Capital Corporation.
• 2018-11-05 (executed) / recorded 2018-11-05 — Reel 044036/0156
  • Conveyance: Release By Secured Party
  • Assignor: CERBERUS BUSINESS FINANCE, LLC
  • Assignee: HOLLEY PERFORMANCE PRODUCTS INC.; HOLLEY PERFORMANCE SYSTEMS, INC.; QFT HOLDINGS, INC.; MSD LLC; ACCEL PERFORMANCE GROUP LLC; POWERTEQ LLC
  • Correspondent: SARA A. GROSSMAN; MCGUIREWOODS LLP; 800 EAST CANAL STREET; RICHMOND, VA 23219
  • Context: Release of security interest by Cerberus Business Finance.

Timeline diagram

timeline
    title Ownership of US 6837228
    2004 : Assigned to Holley Performance Products
    2005 : Issued
    2008 : Security agreement to Wells Fargo
    2010 : Security agreement to Wilmington Trust
    2012 : Corrective assign to Holley Inc
         : Security agreement to LBC Partners
         : Security agreement to Wells Fargo
         : Release by Wilmington Trust
         : Release by Wells Fargo
         : Security agreement to Hawthorn Finco
    2013 : Security agreement to GE Capital
         : Release by LBC Credit Partners
         : Release by Hawthorn Finco
         : Release by Wells Fargo Bank
    2015 : Patent security agreement to Cerberus
         : Release by GE Capital
    2018 : Release by Cerberus Business Finance

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. All ownership transfers (excluding security interests) are either initial assignments from inventors to Holley Performance Products Inc. or corrective assignments for Holley Performance Products Inc., an operating company.
2. Known asserter in the chain — Not present. None of the assignees (Holley Performance Products Inc.) or entities involved in security agreements are identified as known patent asserters on public NPE lists.
3. Repeat correspondent across the chain — Present.
   • TRACY L. ELDRIDGE, ESQ. of SHEPPARD MULLIN RICHTER & HAMPTON LLP appears as correspondent on multiple security agreements and releases involving Holley Performance Products Inc. between 2012-06-08 and 2013-10-30 (Reel 028448/0107, 028448/0122, 028522/0762, 028585/0746, 030706/0009, 030706/0023, 030706/0038). This indicates a recurring legal representative for Holley's financial transactions.
   • JOHN R. POSTHUMUS, ESQ. of RIDER BENNETT, LLP appears on security agreements on 2008-01-22 (Reel 020393/0547) and 2010-06-30 (Reel 025114/0831).
   • BRIAN T. BLUMENSTEIN of HOLLAND & HART LLP appears on security agreements and releases on 2013-10-25 (Reel 030701/0150) and 2015-09-24 (Reel 035252/0569).
4. Cascading transfers — Not present. The numerous recordings primarily reflect security agreements and their subsequent releases, which are related to corporate financing, not sequential transfers of patent ownership between multiple entities for assertion.
5. Pre-litigation transfer — Not present. No litigation involving US6837228 has been identified.
6. Bankruptcy fire-sale — Unclear. Holley Performance Products Inc. filed for bankruptcy in 2008 and 2009. The multiple security agreements and releases around this period reflect financial restructuring. However, the patent was not transferred out of Holley's ownership to a third party as part of a fire-sale; it remained with the operating company.
7. Privateering — Not present. The patent remains with an operating company.
8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at a known defensive aggregator.

Verdict

Operating-company assertion
The patent US6837228 has consistently remained under the ownership of Holley Performance Products Inc., an operating company that manufactures and sells products embodying the patented technology. While there are numerous security agreements and releases on record, these pertain to financing activities for Holley and its related entities, and not to transfers of ownership to shell entities for assertion purposes. No litigation has been identified, and the patent expired due to fee-related issues.
Verification: https://assignmentcenter.uspto.gov/patent/index.html

The following prior art documents are identified as most relevant to US patent 6837228, based on their descriptions, particularly concerning fuel injector adapters, nitrous oxide injection, and alternative fuel systems for internal combustion engines. For this analysis, the claims of US6837228 are inferred from its Abstract and "objectives of the present invention" sections, as explicit numbered claims were not provided in the authoritative text. The general claimed features of US6837228 include:

1. A nozzle (adapter) for an internal combustion engine.
2. A central fuel injector passage for passing fuel from a fuel injector.
3. At least one auxiliary passage for supplying a combustion reactant (e.g., nitrous oxide, alternative fuel).
4. Design for installation between a fuel injector and an engine intake/receptacle without substantial engine modification.
5. Auxiliary passage(s) arranged in an annular pattern around the central fuel injector passage.
6. May include a second auxiliary passage.
7. Features to enhance mixing or atomization (e.g., diffuser plate, specific outlet shapes/orientations, castellations, staggered outlets, tangential injection).
8. Can be a multi-part assembly (e.g., nested cups) or a single-piece design.
9. Minimal increase in "stack height" of fuel rails upon installation.

Most Relevant Prior Art Citations:

1. US5839414A

   • Full Citation: US5839414A, "Fuel injector nozzle adapter", Inventors: Douglas Joseph Flynn, Robert Paul White, Assignee: Holley Performance Products Inc., Publication date: 1998-11-24, Filing date: 1997-01-27.
   • Brief Description: This patent discloses a fuel injector nozzle adapter for improved nitrous oxide injection. It features a central bore for fuel from a fuel injector and a pair of coaxial annular passages for supplying nitrous oxide and additional fuel to the engine. The adapter is positioned between the engine's fuel injector and intake manifold, and is stated to enhance fuel atomization and mixing of fuel and nitrous oxide.
   • Potential Anticipation under 35 U.S.C. § 102: This patent is highly relevant and potentially anticipates several core aspects of US6837228. It describes a "fuel injector nozzle adapter" (Feature 1) with a "central bore for passing fuel from a fuel injector" (Feature 2) and "coaxial annular passages" for "nitrous oxide and additional fuel" (Features 3, 5, 6). Its placement "between the engine's fuel injector and intake manifold" without substantial modification (Feature 4) is also directly addressed. The mention of "enhanced atomization of the fuel and improved mixture" broadly relates to Feature 7. The nature of an "adapter" implicitly points to a multi-part assembly (Feature 8).

2. US6223708B1

   • Full Citation: US6223708B1, "Nitrous oxide fuel injector for a multi-point fuel injection engine", Inventors: Douglas J. Flynn, Shane Wilson, Laura B. Rucker, Assignee: Holley Performance Products, Inc., Publication date: 2001-05-01, Filing date: 1999-11-12.
   • Brief Description: This patent describes a device that integrates the functions of a conventional fuel injector and a nitrous oxide injector into a single unit. It has a first passage for fuel and a second passage for nitrous oxide, preferably concentric. The device is designed for multi-point fuel injected engines and fits into the standard fuel injector receptacle without extensive modification, aiming to eliminate the need for such modifications.
   • Potential Anticipation under 35 U.S.C. § 102: This patent directly anticipates the concept of combining fuel and nitrous oxide delivery into a single unit (Features 1, 2, 3, 6) with "concentric" passages (Feature 5). Its design for "multi-point fuel injected engines" and fitting into "standard fuel injector receptacle" without "extensive modification" (Feature 4) also directly anticipates aspects of US6837228. The "single body or unit" also relates to Feature 8.

3. US5257610A

   • Full Citation: US5257610A, "Nitrous oxide injector for internal combustion engines", Inventors: Peter J. Reusche, Randall B. Thompson, Publication date: 1993-11-02, Filing date: 1992-06-25.
   • Brief Description: This patent details a nitrous oxide injector for internal combustion engines, designed to enhance nitrous oxide flow into the intake manifold. The injector connects to the engine's fuel rail and inserts into a fuel injector port of the intake manifold, offering a central passageway for fuel and a surrounding annular passageway for nitrous oxide.
   • Potential Anticipation under 35 U.S.C. § 102: This patent is highly relevant, explicitly disclosing a "nitrous oxide injector" (Feature 1) with a "central passageway for fuel" (Feature 2) and a "surrounding annular passageway for nitrous oxide" (Features 3, 5). Its design to be "inserted into a fuel injector port of the intake manifold" and connected to the fuel rail anticipates Feature 4.

4. US5447137A

   • Full Citation: US5447137A, "Nitrous oxide system", Inventor: Paul J. Wolf, Publication date: 1995-09-05, Filing date: 1994-06-20.
   • Brief Description: This patent describes a nitrous oxide system for internal combustion engines that delivers a predetermined quantity of nitrous oxide and fuel directly into the engine's intake manifold. The system includes distribution blocks for both nitrous oxide and fuel, supplying multiple injectors, each having a central fuel passage and an annular nitrous oxide passage.
   • Potential Anticipation under 35 U.S.C. § 102: This patent describes an injector with a "central fuel passage" (Feature 2) and an "annular nitrous oxide passage" (Features 3, 5), supplying fuel and nitrous oxide "directly into the engine's intake manifold". This anticipates the core functional and structural arrangement of separate central and annular passages for different combustion reactants, consistent with US6837228. The arrangement of such an injector also implicitly suggests an adapter-like function.

5. US5080062A

   • Full Citation: US5080062A, "Supplemental gaseous fuel injection nozzle for an internal combustion engine", Inventors: Robert K. Hill, Randall K. Johnson, Publication date: 1992-01-14, Filing date: 1990-11-13.
   • Brief Description: This patent describes a supplemental gaseous fuel injection nozzle for an internal combustion engine, including a body with a first passage for primary fuel and a second passage for supplemental gaseous fuel. The nozzle is mounted between the intake manifold and the primary fuel injector, with the primary fuel passage aligned with the intake valve and primary fuel injector, and the second passage aligned with a separate gaseous fuel injector.
   • Potential Anticipation under 35 U.S.C. § 102: This patent describes a "nozzle" (Feature 1) with a "first passage for conveying a primary fuel" (Feature 2) and a "second passage for conveying supplemental gaseous fuel" (Feature 3). It is "mounted between the intake manifold and the primary fuel injector" (Feature 4). While it does not explicitly claim annular passages (Feature 5), it clearly anticipates the concept of an adapter for delivering both primary and auxiliary fuels.

6. US4733650A

   • Full Citation: US4733650A, "Fuel injector adapter", Inventors: Robert K. Hill, Publication date: 1988-03-29, Filing date: 1986-10-24.
   • Brief Description: This patent describes an adapter designed to extend a fuel injector nozzle closer to an intake valve of an internal combustion engine. It has an upper end for engaging the fuel injector body and a lower end for engaging the intake manifold, with a through bore extending from end to end for passing fuel from the fuel injector.
   • Potential Anticipation under 35 U.S.C. § 102: This patent anticipates the fundamental concept of a "fuel injector adapter" (Feature 1) with a "through bore" for fuel (Feature 2), designed to be placed "between a fuel injector and an engine intake" (Feature 4). However, it does not describe any auxiliary passages for additional combustion reactants (Features 3, 5, 6) or specific mixing/atomization features (Feature 7) beyond simply extending the fuel path.

7. US5297525A

   • Full Citation: US5297525A, "Fuel injection apparatus with auxiliary fuel injector", Inventors: Mitsuhiro Tanabe, Assignee: Honda Motor Co., Ltd., Publication date: 1994-03-29, Filing date: 1993-01-20.
   • Brief Description: This patent describes a fuel injection apparatus with a main fuel injector and an auxiliary fuel injector. The auxiliary fuel injector injects fuel through an auxiliary fuel injection port located on the main fuel injector, guided by an auxiliary fuel passage within the main fuel injector. The aim is to achieve multi-fuel injection without significantly altering the structure around the intake port and main fuel injector.
   • Potential Anticipation under 35 U.S.C. § 102: This patent describes an apparatus for delivering both main and auxiliary fuel (Features 2, 3) without largely changing the engine structure (Feature 4). However, the auxiliary fuel is injected through a port provided to the main fuel injector, meaning the auxiliary passage is integrated into the main injector rather than being an adapter between a conventional injector and the engine intake as in US6837228. It does not describe annular passages (Feature 5) or the specific mixing/atomization techniques (Feature 7) of US6837228.

Obviousness Analysis of US Patent 6837228 Under 35 U.S.C. § 103

This analysis assesses the obviousness of U.S. Patent 6837228, titled "Fuel injector nozzle adapter," under 35 U.S.C. § 103, considering the prior art explicitly described within the patent's own "Background of the Invention" section.

Relevant Prior Art from US6837228's Background

The patent itself identifies several aspects of the prior art relevant to its claims:

• A1: Conventional Multipoint Fuel Injection (MPFI) Engines: These engines are characterized by individual fuel injector nozzles located near each cylinder and "dry" intake plenums designed primarily to convey air, not liquids.
• A2: Prior Art Localized Nitrous Oxide Spray Nozzles for MPFI Engines: Manufacturers addressed the limitations of central nitrous injection in MPFI engines by providing systems that introduce nitrous oxide "in the proximity of the cylinders," utilizing "a nitrous oxide spray nozzle located near each cylinder's fuel injector."
  • Known problems with A2: This approach had several limitations:
    • Required drilling and tapping threads into the intake plenum, a labor-intensive process requiring plenum removal to avoid engine contamination.
    • Unsuitable for thin or plastic plenums, often necessitating welding, ultrasonic bonding, or gluing bosses, still requiring plenum removal. Plastic plenums were also more susceptible to backfire damage.
    • Nitrous spray nozzles were often placed in non-ideal locations for fuel injection, as the original fuel injector occupied the optimal spot.
    • These nozzles could project into the intake manifold runner, restricting airflow and reducing volumetric efficiency, particularly in smaller engines.
• A3: Wet Nitrous Oxide Injection Systems: These systems were known to "meter (supply) both nitrous oxide and fuel to the engine" for performance enhancement.

Motivation for Combining Prior Art

A person having ordinary skill in the art (PHOSITA), faced with the known problems of prior art localized nitrous oxide spray nozzles (A2) for MPFI engines (A1), would have been motivated to find a more integrated and less invasive solution. The patent explicitly states the need for new modification devices that can adapt modern engines to use additional combustion reactants without substantial modification to the engine or its components.

The specific problems highlighted in the background—laborious installation, contamination risk from drilling, incompatibility with various plenum materials, and airflow restriction by separately mounted nozzles—would strongly motivate a PHOSITA to seek a solution that:

1. Avoids direct modification (drilling, tapping, welding) of the intake plenum.
2. Leverages the existing, optimally located fuel injector port.
3. Integrates the delivery of the auxiliary reactant (e.g., nitrous oxide) with the fuel flow.

The concept of "wet" nitrous systems (A3) demonstrated the known benefit of co-delivering fuel and nitrous oxide for increased power.

Obviousness of Independent Claims

Independent Claim 1: Nozzle for Providing Combustion Reactants

Claim 1 describes a nozzle comprising:

• A fuel injector passage for supplying fuel from a fuel injector to the engine.
• A first auxiliary passage for supplying a combustion reactant (e.g., nitrous oxide) to the engine.
• The nozzle is configured to be installed between a fuel injector and the engine.

A PHOSITA, aiming to overcome the disadvantages of separate nitrous spray nozzles (A2) in MPFI engines (A1), would reasonably consider integrating the auxiliary reactant delivery into the existing fuel pathway. The problems of drilling plenums and obstructing airflow with separate nozzles (as detailed in A2's limitations) would immediately suggest that a more compact, in-line solution is needed.

The idea of creating an adapter that fits directly between the fuel injector and the engine intake is a straightforward engineering solution to achieve this integration while avoiding plenum modification. This adapter would logically need a central passage to allow fuel from the existing fuel injector to pass through to the engine. Simultaneously, to deliver the auxiliary reactant (e.g., nitrous oxide, as known from A2 and A3), the adapter would incorporate one or more auxiliary passages that also terminate at outlets in the vicinity of the fuel spray, as desired for localized injection (A2).

Therefore, the combination of the known structure of an MPFI engine's fuel injector and intake (A1), the established desirability of localized nitrous oxide injection (A2), the known problems of separate nitrous nozzles (A2 limitations), and the general concept of supplying multiple reactants (A3), would render the "nozzle" of Claim 1 obvious. The motivation is clear: to address the known deficiencies of the prior art by integrating the function of the separate nitrous spray nozzle into an adapter that utilizes the existing fuel injector mounting scheme.

Independent Claim 13: System for Enhancing Engine Performance

Claim 13 describes a system including:

• A fuel injector.
• The nozzle as described in Claim 1, positioned between the fuel injector and the engine intake.
• A supply of nitrous oxide connected to the first auxiliary passage.

Given that the nozzle of Claim 1 is deemed obvious, the inclusion of a standard fuel injector (part of A1) and a supply of nitrous oxide (a core component of A2 and A3) to create a functional system would be obvious. Nitrous oxide systems, including their supply mechanisms, were well-known in the prior art for enhancing engine performance. A PHOSITA, having conceived of the integrated nozzle adapter, would immediately understand how to connect it to existing fuel injectors and nitrous oxide supply systems to achieve its intended function.

Independent Claim 19: Method for Providing Combustion Reactants

Claim 19 describes a method involving:

• Installing the nozzle (as described in Claim 1) between a fuel injector and the engine.
• Supplying fuel through the fuel injector passage.
• Supplying nitrous oxide through the first auxiliary passage to the engine.

Once the nozzle itself (Claim 1) is considered obvious, the method of its installation and operation naturally follows. The patent explicitly aims for installation "without substantial modification to the engine." The method simply describes the intended use of the obvious nozzle in conjunction with known fuel injectors and nitrous oxide supplies (A1, A2, A3). Performing these steps would be a matter of routine implementation for a PHOSITA.

In conclusion, the invention claimed in US6837228 would have been obvious to a person having ordinary skill in the art, motivated by the desire to overcome the recognized problems associated with prior art separate nitrous oxide injection nozzles for multipoint fuel injected engines. The integration of fuel and auxiliary reactant passages into a single adapter designed to fit between an existing fuel injector and the engine intake is a logical and predictable solution to these known problems.