US 4683843

I'll search for authoritative records on this patent number, including any litigation or CAFC activity.

Let me check specifically for any litigation, PTAB, or Federal Circuit activity.

US Patent 4,683,843 — Summary

Caveat on scope: I searched for this specific number. I found no Federal Circuit (2026 or otherwise), district court, PTAB/IPR, or ITC record involving US 4,683,843. Given the patent's fee lapse in 1999 (see below), such activity is highly improbable. Anything asserted to the contrary would need a live docket citation. I also note that the string "4683843" appears as JP Patent No. 4683843 B2 (Kyocera, artificial nucleus pulposus disc, A61L27/00) — an unrelated document in a different jurisdiction. I am not conflating the two.

Bibliographic data (per Google Patents / USPTO record)

Abstract (as issued)

A fuel-charging system injecting nitrous oxide into a high-performance vehicle engine for an instant burst of power. A nitrous oxide supply line feeds pressurized nitrous oxide from a container through a spray bar. A normally closed solenoid valve controls flow into the engine. The supply line also connects to a vent tube having a normally open solenoid valve, which communicates with a one-way, low-pressure-actuated check valve, venting nitrous oxide that leaks past the closed control valve to atmosphere to prevent harmful buildup in the engine. A pair of pressure-actuated electrical switches (oil and fuel pressure) prevent actuation of the nitrous oxide control valve if insufficient fuel is available to mix with the nitrous oxide and if engine RPM is insufficient. The check valve reduces momentary back pressure in the nitrous oxide line. The vented leaking nitrous oxide is visible to the operator.

Independent claims — plain language

The patent has 17 claims total, with two independent claims (1 and 11); claims 2–10 depend from claim 1 (or from claims 2/8), and claims 12–17 depend from claim 11 (or 13/14/15).

Claim 1 — An improvement to a known type of nitrous oxide fuel-charging system (pressurized liquid N₂O supply + spray means + a control valve governing N₂O flow to the spray means). The improvement is: a first valve communicating with the control valve, plus means that (a) open the first valve when the control valve is closed, so any N₂O leaking past the closed control valve vents to atmosphere, and (b) close the first valve when the control valve is open, blocking flow to atmosphere. Essentials: the leak-vent valve is inversely slaved to the main N₂O control valve.

Claim 11 — A complete system comprising: (a) a pressurized liquid nitrous oxide supply; (b) injection means connected to the supply for injecting N₂O into the engine; (c) a first valve (open/closed) controlling N₂O flow from supply to injection means; (d) vent means communicating with the first valve for discharging to atmosphere any N₂O leaking past it when closed; and (e) a second valve connected between the first valve and the injection means and communicating with the vent means, which (i) reduces backflow of N₂O from the injection means into the vent means and (ii) blocks low-pressure N₂O from entering the injection means. In other words: main control valve + fail-safe vent path + a combined anti-reversion/low-pressure-blocking check valve.

Notable dependent-claim limitations: check valve cracking pressure described as 50–75 psi (specification, supporting claim 2); vent tube located adjacent the front windshield for visual leak indication (claim 3); in-cabin manual shut-off valve (claim 4); fuel-pressure switch (claim 5) and oil-pressure switch (claim 6) gating actuation; normally open vent solenoid / normally closed control solenoid / driver push-button DC circuit (claims 7, 9, 10); relay in the control circuit (claim 16); third valve controlling fuel flow into the injection system (claim 17).

Drafting note (uncertainty flag): Claim 9 recites pressure valves that prevent "the closing of said control valve means if the pressure of the engine fuel or oil is below a predetermined level" — a literal reading that appears internally inconsistent with the specification (which says low fuel/oil pressure prevents actuation/opening). I am reporting the claim text as issued rather than correcting it.

Confidence and uncertainty

• High confidence on title, inventors, assignee chain, filing/issue dates, abstract, and claim text — these come from the full patent document and corroborating records (Google Patents, Justia, OSTI ID 6395446, and later patents citing the number).
• No authoritative evidence found of any CAFC 2026 docket, litigation, or post-grant proceeding involving US 4,683,843. Absence of evidence here is reasonably strong given the patent lapsed for nonpayment of maintenance fees effective 1999-08-04 (well before any 2026 appeal could arise).
• The statutory term would have run to 2006-08-13, but the patent's enforceable life ended earlier via the 1999 fee lapse.

I'll search for litigation involving US patent 4683843.

Let me search more targeted litigation databases.

Litigation search results for U.S. Patent No. 4,683,843

Conclusion: I found no evidence of any litigation involving U.S. Patent No. 4,683,843.

I searched for the specific number "4683843" / "4,683,843" paired with litigation, infringement, lawsuit, plaintiff/defendant, CourtListener, PACER-adjacent sources, and the Unified Patents portal. No district court case, Federal Circuit appeal, ITC action, or PTAB proceeding (IPR/PGR/CBM) naming this patent as the patent-in-suit appeared.

What the searches did return (and why each is not this patent)

Direct answer to your requested data fields

Because no case exists in the sources I could reach, there is no plaintiff, defendant, jurisdiction, case number, filing date, or outcome to report. I will not fabricate these fields.

Relevant context from the patent's own record (not litigation, but bearing on enforceability)

• Prosecution/ownership: Filed 1986-08-13; granted 1987-08-04 (US 4,683,843 A). Original assignee Ram Automotive Company (Columbia, South Carolina); assigned to BG 300, Inc. effective 1990-12-07 (recorded 1992-02-18). Inventors: John A. Norcia, William M. Wheatley, Michael D. Norcia.
• Maintenance fees / status: According to the Google Patents legal-events record, the 4-year fee was paid (1990-08-27) and the 8-year fee was paid (1995-02-03), but a maintenance-fee reminder issued 1999-02-23, followed by "Lapse for failure to pay maintenance fees" (1999-08-01) and "Lapsed due to failure to pay maintenance fee" effective 1999-08-04. The record also shows a 2018-01-30 entry: "Patent expired due to nonpayment of maintenance fees under 37 CFR 1.362."
• Practical implication: Any infringement suit asserting this patent would have had to be filed while it was still enforceable — i.e., before the 1999 lapse. My searches turned up no such suit.

Confidence and limitations

• High confidence that there is no readily indexed U.S. litigation (district court or CAFC) involving US 4,683,843, given: (a) the patent lapsed in 1999; (b) it concerns a narrow 1980s nitrous-oxide racing accessory; and (c) repeated targeted searches on patent-litigation aggregators returned nothing.
• Caveat: I could not directly query PACER (which requires a paid account) or run a full Docket Navigator / Lexis CourtLink / Westlaw LitAlert "KeyCite" patent-history report — the same tools the USPTO examiner used in the sample above. Very old, unindexed, or state-court/non-reported actions could exist without appearing in free search results. If you need a certifiable "no litigation" opinion, a paid Docket Navigator or Lexis/Westlaw patent litigation history report on U.S. Patent No. 4,683,843 is the appropriate next step.

If you'd like, I can attempt additional targeted searches (e.g., by assignee names "Ram Automotive," "BG 300," or inventor "Norcia" combined with "infringement") using the remaining tools, though the searches above already covered that ground.

I'll verify the ODP result with targeted searches before finalizing.

Proceedings overview

There are zero AIA trial proceedings on file for US 4,683,843 — the USPTO Open Data Portal returns no IPR, PGR, or CBM for this patent, and nothing in my searches surfaced a petition that ODP had missed. The breakdown is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials. The reason is not that the patent is hardened: the patent lapsed for nonpayment of the 12-year maintenance fee, effective 1999-08-04 (USPTO legal events: REMI 1999-02-23, LAPS 1999-08-01, FP 1999-10-12, effective date 1999-08-04), roughly thirteen years before AIA trials began on 2012-09-16. A defendant's bottom line is stronger than any IPR outcome could deliver: the asserted claims cannot be infringed because the patent is expired, and there is no continuation, reissue, or other live progeny in the family (Family Applications (1) — only US 06/896,055).

Note the discrepancy in the record: Google Patents lists an "anticipated expiration" of 2006-08-13 (20 years from filing under 35 U.S.C. § 154(a)(2)), but the fee-lapse events control. The patent died in 1999, and a 2018-01-30 STCH entry confirms expiry for nonpayment under 37 C.F.R. § 1.362. Google's own status line reads "Expired - Fee Related."

No proceeding to report — and that is the finding, not a gap in research

The "PTAB proceedings on file" block states plainly that ODP shows no AIA trial proceedings as of the most recent ingest. I ran independent searches (patent number plus "IPR," "PTAB," "inter partes review petition," and litigation/appeal queries) and found no petition, no institution decision, no Final Written Decision, and no Federal Circuit appeal involving 4,683,843. Because no proceeding exists, the per-proceeding fields you asked for — judge panel, grounds, institution reasoning, FWD claim-level verdict, settlement, CAFC docket number — have no content to report. I will not invent a proceeding number to fill the template.

What the record does show about this patent's history:

• Filing / grant: US 06/896,055 filed 1986-08-13; granted 1987-08-04. Seventeen claims (independent claims 1 and 11).
• Inventors / ownership: John A. Norcia, William M. Wheatley, Michael D. Norcia; assigned to Ram Automotive Company (assignments recorded 1986-08-13, effective 1986-07-30), then to BG 300, Inc. (recorded 1992-02-18, effective 1990-12-07). This matters: BG 300, not Ram, is the entity that would have had standing to sue during the patent's remaining life, and BG 300 did not pay the 12-year fee.
• Prosecution-era prior art: only two references cited by the examiner, both the patent owner's own earlier patents — US 4,494,488 ("Fuel charging system for high performance vehicles") and US 4,572,140 ("Nitrous oxide precooler"), plus three non-patent citations including Ganahl, Superpower Nitrous Oxide Injection (1977), p. 64.
• Post-issuance status of the claims: all 17 claims stand exactly as granted. They were never canceled, narrowed, or amended in any trial — but they also have no enforceable life. Claims 1, 2, 5, 6, 8–11, 13–17 (the ones a demand letter would most likely cite: the vent-valve interlock of claim 1, the check valve of claim 2, the fuel-pressure switch of claim 5, the oil-pressure switch of claim 6, and the apparatus claims 11–17) are all expired, unamended, and untested.
• Citation footprint vs. assertion footprint: this patent is heavily cited as prior art — 23 "cited by" entries in the primary table and 39 in the expanded list, from Furrow (US 4,840,157) through Kook (US 10,788,007, 2020). Third-party citations of a 1987 nitrous patent by later Holley, Competition Cams, and Atherley filings are a normal art-trail signal and are not evidence of assertion or of PTAB exposure.
• Pre-AIA reexamination: the structured block covers AIA trials only. I found no evidence of an ex parte or inter partes reexamination of 4,683,843, but I could not verify the absence exhaustively — treat that as a low-confidence negative. Any reexamination certificate would appear in the PatentCenter file wrapper, which is worth a two-minute pull if you need certainty.

One result to actively discount. A search surfaced a PTAB ex parte appeal (Appeal 2016-006440, Application 12/398,783) discussing a "variable safety control valve" for a nitrous oxide delivery mask, with the examiner relying on a Porter nitrous oxide sedation system. That is a prosecution appeal of a different, unrelated application in the nitrous oxide space. It has no bearing on 4,683,843 and is not a proceeding on this patent.

Strategic summary

Claim status. All 17 claims of 4,683,843 remain textually intact — nothing is canceled, nothing is sustained-over-art, nothing is untested-because-everything-is-untested. But "intact" and "enforceable" are different things here. The patent expired 1999-08-04 for failure to pay the 12-year maintenance fee, and the ODP legal-status block says "Expired - Fee Related." An expired patent cannot be infringed; infringement requires a subsisting right. So the operative claim-status answer to a defendant is: claims 1–17 are expired, not "surviving."

Estoppel landscape. Because no IPR, PGR, or CBM was ever filed, there is no § 315(e)(2) estoppel against anyone — and that is academic. There is also no IPR-art record, no FWD construction, and no Board claim construction to inherit. Your invalidity case, if you ever needed one, is built on the printed record: US 4,494,488, US 4,572,140, and Ganahl (1977) were before the examiner, so § 102/§ 103 attacks built on those three would carry the burden of showing the examiner erred — but you will almost certainly never need to reach this because of expiration. Correspondingly, there is no § 315(b) one-year bar clock to worry about and no § 325(d) discretion risk, since the PTAB window is irrelevant to a dead patent.

Pattern signals. No petitioner filed anything, ever — no repeat petitioner, no defensive aggregator (no Unified Patents or similar entity appears anywhere in the record), and no patent-owner appeal activity, because there were no adverse decisions to appeal. The absence of PTAB activity here is not the "well-asserted patents eventually attract IPRs" signal. It is explained on the timeline: AIA trials started 2012-09-16; this patent had been lapsed since 1999-08-04, and Family Applications (1) confirms there is no continuation or reissue that could carry the 1986 disclosure forward into a live right. Whoever asserts this patent would be asserting a 1987 grant that has been in the public domain since before Y2K.

Recommended next steps

• If you have received a demand citing US 4,683,843, the demand is baseless on its face. Put the maintenance-fee lapse events in your response letter and cite the ODP record: REMI 1999-02-23, LAPS 1999-08-01, FP (lapsed due to failure to pay maintenance fee) 1999-10-12, effective date 1999-08-04. Under 37 C.F.R. § 1.362, a patent that lapses for nonpayment expires at the end of the grace period and cannot be infringed thereafter. Verify against the fee record at PatentCenter and the statutory basis at 37 C.F.R. § 1.362 before sending; also pull the file wrapper to confirm no petition to revive under § 1.378 was ever granted (a revival would only extend the term to the nominal 2006-08-13 date, which is itself twenty years past).
• Confirm there are no live relatives before you rely on expiration alone. The family table shows a single application (US 06/896,055) and no reissue or continuation. If the demand nevertheless threatens a different patent number, treat that as a new matter and run a fresh ODP/PatentCenter check on that number — do not assume it is this family.
• Check for catch-and-release tactics. A demanding party that knows of the 1999 lapse may rely on a target's not checking. If the letter cites the claims of 4,683,843 specifically (e.g., claim 1's vent-valve-when-control-valve-closed limitation, claim 6's oil-pressure switch, or claim 11's apparatus), that citation to a 1999-expired claim is a strong indicator of a copy-paste demand rather than a genuine infringement theory.
• If a counterparty instead points you at the modern nitrous art, remember that the live patents in this field are the ones citing 4,683,843 (e.g., the Holley/Mills and Atherley families in the "cited by" list), and those are where real PTAB risk and real estate risk live. Absence of PTAB activity on a 1986 patent tells you nothing about them.
• No PFW/trial-stage deadlines to track. There is no institution decision deadline, no oral hearing, and no statutory one-year FWD date, because there is no trial. There is also nothing to monitor on the Federal Circuit docket via CourtListener — no appeal of any PTAB decision on this patent exists.

Confidence and caveats. High confidence that no AIA trial proceeding exists for 4,683,843 and that the patent lapsed effective 1999-08-04. Lower confidence on the absolute absence of pre-AIA reexamination — I found no evidence of one, but the structured data block covers AIA trials only, so verify via the PatentCenter file wrapper if that point matters. I did not locate any district court litigation involving this patent number, but a full Docket Navigator or PACER check would be the way to confirm that negative.

I'll verify the assignment record and the corporate history of the parties before building the chain.

Ownership analysis — US 4,683,843 ("Nitrous oxide fuel injection safety system")

Scope note on sources. I was able to retrieve the patent's full text and its recorded legal-events data (which is a mirror of the USPTO assignment file), but I could not open the Assignment Center record itself (https://assignmentcenter.uspto.gov/) to read the assignment-document images. That matters for one specific field: the correspondent of record for both recordings is not exposed in the data I retrieved, and I am not going to invent an attorney name. Everything below is grounded in reel/frame numbers and dates that appear in the patent's own legal-events record; the two BG 300 corporate-side reel references are cross-referenced from a different BG 300 patent and are flagged as such.

Inventors

Pattern check — inventors departing the original assignee. Not present. All three inventors executed a pre-filing assignment of their entire interest to Ram Automotive Company on 1986-07-30, two weeks before the 1986-08-13 filing date (Reel 004591/0128). That is a routine employee/founder assignment, not a fire-sale precursor. I found no evidence of inventor departure, and no later inventor-side recordings. Caveat: "employer" here is inferred from the assignment itself and from the two co-pending Ram Automotive patents (US 4,494,488 and US 4,572,140, both cited on the face of this patent) — the assignment document itself does not state employment.

Original assignee

Ram Automotive Company, recorded on the assignment as "Ram Automotive Company, Columbia, South Carolina," and identified on the issued patent's front page as a corporation of Ohio (a discrepancy worth noting: the Ohio-vs-South-Carolina distinction resurfaces in the 1992 transfer, see below).

• Primary line of business: nitrous-oxide fuel-charging systems for high-performance/racing vehicles. This patent is one of a three-patent family (with US 4,494,488 and US 4,572,140) all directed to the same commercial kit — a spacer plate with a spray bar, solenoid N₂O and fuel valves, bottle, and lines.
• Did they ship a product embodying the claims? The specification describes an installed, driver-operated system with a cabin-mounted push button, spray bar, bracket-mounted solenoid valves and a vent tube run to the windshield — i.e., a producible hardware kit, not a paper design. Secondary sources corroborate this as Ram's actual product line: OSTI records the assignee as "Ram Automotive Co., Columbia, SC" (https://www.osti.gov/biblio/[6395446](/patent/6395446)). I did not locate an independent Ram Automotive product catalogue, so treat "shipped product" as probable but not independently documented.
• Current status: The original owner is no longer in the chain — the South Carolina entity assigned the patent to BG 300, Inc. effective 1990-12-07 (recorded 1992-02-18). I found no bankruptcy, dissolution or merger filing for Ram Automotive in the sources I could reach; status should be treated as unverified.

Assignment timeline

Two assignments are recorded against this patent. That is the complete chain.

• 1986-07-30 (executed) / recorded 1986-08-13 — Reel 004591/0128

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: John A. Norcia; William M. Wheatley; Michael D. Norcia (jointly, all right title and interest)
  • Assignee: Ram Automotive Company (Columbia, South Carolina)
  • Correspondent: not exposed in the retrieved record — the assignment-data mirror does not carry a correspondent field for this pre-1990s recording, and I could not open the Assignment Center image to read it. No correspondent can be reported without fabrication.
  • Context: standard pre-filing inventor-to-company assignment (founded the ownership chain; the patent then issued to Ram Automotive on 1987-08-04).

• 1990-12-07 (executed) / recorded 1992-02-18 — Reel 006014/0926

  • Conveyance: Assignment of Assignors' Interest (expressly an assignment, not a merger or change-of-name — this distinction matters, see NPE signal 1)
  • Assignor: Ram Automotive Company of South Carolina, Inc.
  • Assignee: BG 300, Inc. (Georgia)
  • Correspondent: not exposed in the retrieved record — same limitation as above. Cannot be reported.
  • Context: ordinary commercial sale/transfer of the nitrous-oxide product line to a competitor-marketed operating company. Note the assignor's name changed between the two recordings — the 1986 assignee was an Ohio corporation, the 1992 assignor is a South Carolina corporation, and the conveyance type recorded is a straight assignment rather than a merger or change of name. Whether the SC entity is the same enterprise reincorporated or a successor that had already acquired the assets is not determinable from the records I retrieved.

• Post-1992: no further recorded assignment against US 4,683,843. The remaining legal events are fee-related:

  • 1990-08-27 — 4-year maintenance fee paid; 1995-02-03 — 8-year maintenance fee paid
  • 1999-02-23 — maintenance-fee reminder mailed; 1999-08-01 — lapse for failure to pay; 1999-10-12 — recorded as lapsed due to failure to pay maintenance fee, effective 1999-08-04
  • 2006-08-13 — anticipated expiration date (20 years from filing), and a 2018-01-30 status entry confirming expiration for non-payment under 37 CFR 1.362. The 1999 lapse and the 2006 full-term expiry are in tension; the most consistent reading is that the 1999 lapse was later cured or the fee was paid in the grace period, since the file anticipates a 2006 expiry. Flagging rather than resolving.

Corporate-side cross-references on other BG 300 patents (not recorded against this patent — tagged from a Google Patents legal-events listing on US 5,211,205, so treat as leads not findings): an assignment to BG 300, Inc. from Barry Grant and Michael E. Harris effective 1992-07-10, Reel 006197/0922; a security agreement to Branch Banking and Trust Company (Georgia) against "Grant, Barry S.," Reel 022162/0214, recorded ~2009-12-23; and an assignment from BG 300, Inc. to High Performance Industries, Inc. (Kentucky), Reel 026565/0143, ~2011-07-06. These support the conclusion that BG 300, Inc. is the Barry Grant performance-parts enterprise (BG Fuel Systems / Demon Carburetion / NitrousWorks per Hemmings and trade coverage of Barry Grant Inc. ceasing operations). None of these reel/frame numbers appears in US 4,683,843's own legal-events record, which is unsurprising: this patent had already expired by 2006, before the 2009 security agreement and 2011 transfer.

Timeline diagram

timeline
    title Ownership of US 4683843
    1986 : Filed by Ram Automotive
         : Inventors assign to Ram Automotive
    1987 : Patent issued on Aug 4
    1990 : Ram SC entity assigns to BG 300
    1992 : Assignment recorded at Reel 006014
    1999 : Maintenance fee lapse recorded
    2006 : Anticipated expiration

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The only post-inventor transfer (Reel 006014/0926, executed 1990-12-07) moves the patent from one operating nitrous-oxide parts company to BG 300, Inc., which is the Barry Grant performance-parts enterprise (BG Fuel Systems, NitrousWorks). No "IP / Holdings / Licensing / Ventures" suffix, no registered-agent address, no single-purpose LLC. The recorded conveyance is an assignment, so no merger or name-change ambiguity is being used to obscure identity.

2. Known asserter in the chain — not present. Neither Ram Automotive Company (Reel 004591/0128) nor BG 300, Inc. (Reel 006014/0926) matches Acacia, Marathon Patent Group, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or Spangenberg entities. I could not retrieve the RPX or Unified Patents asserter directories during this session, so this call rests on absence of any litigation record plus the ordinary operating-company character of both assignees — rate it not present on available evidence rather than affirmatively cleared.

3. Repeat correspondent across the chain — unclear / cannot be assessed. This is the one signal the Assignment Center was supposed to answer and the retrieved data does not. No correspondent name or firm appears in the record I could reach for either Reel 004591/0128 or Reel 006014/0926. I decline to name an attorney. To close this out, the images at the Assignment Center (search patent 4,683,843) must be pulled directly and the "correspondent" field read off each of the two abstract-of-title pages.

4. Cascading transfers — not present. Two recordings total, executed ~4.3 years apart (1986-07-30 and 1990-12-07), each a single step. Nothing resembling chained LLCs inside 24 months, and no shared correspondent address is observable because no correspondent data was retrievable.

5. Pre-litigation transfer — not present. I found no infringement action naming US 4,683,843. The transfer that might be scrutinized (Reel 006014/0926) predates the patent's 2006 expiry by 16 years, which is the opposite of a 6-month pre-suit repositioning.

6. Bankruptcy fire-sale — unclear, and not attributable to this patent. There is real distressed-asset activity around BG 300's principal (Barry Grant Chapter 7; BB&T security agreement Reel 022162/0214 ~2009; transfer to High Performance Industries Reel 026565/0143 ~2011; Barry Grant Inc. ceasing operations per Hemmings). But those recordings are not in this patent's legal events, and this patent had lapsed/expired years earlier. This signal is a near-miss on the corporate family, not a finding on this patent.

7. Privateering — not present. No record of an operating company funding an NPE to assert against competitors; the 1990-92 transfer is a straight sale of a product line to another operating company, with no retained assertion interest evident.

8. Defensive aggregator — not present. The chain terminates at BG 300, Inc., not at RPX, AST, LOT, Unified Patents or OIN. No neutralization event.

Verdict

Insufficient data — with the important qualification that the reason is not a missing assignment record. The chain is complete and short: inventors → Ram Automotive Company, Reel 004591/0128 (executed 1986-07-30, recorded 1986-08-13) → BG 300, Inc., Reel 006014/0926 (executed 1990-12-07, recorded 1992-02-18), and then nothing but maintenance-fee events ending in the 2006-08-13 expiry. Zero NPE signals are present, so neither NPE verdict is defensible; but I also cannot upgrade to "operating-company assertion" because that verdict requires the current assignee to be suing actual competitors, and I found no litigation naming this patent at all. The practical conclusion is a benign, two-link operating-company ownership chain in a 1980s aftermarket performance-parts niche, with a residual gap on signal 3 (correspondent of record) that only the Assignment Center document images can close.

Verify at: https://assignmentcenter.uspto.gov/ (search patent number 4683843) and https://assignment.uspto.gov/patent/index.html; legal events mirrored at https://patents.google.com/patent/US4683843/en.

I'll research this systematically — first confirming the USPTO record for 4683843, then digging into each cited reference.

Let me research the non-patent literature cited and confirm there are no additional cited references.

Prior-Art Analysis for US Patent 4,683,843

Building on the previously generated summary and litigation sections. I will not repeat the bibliographic table or claim breakdown there; this section focuses exclusively on the references cited in the "Prior Art" fields of the USPTO/Google Patents record.

1. USPTO "Prior Art" record for 4683843 (as filed)

The Google Patents record for US4683843A lists only two patent citations and three non-patent citations (the third non-patent entry is a duplicate of the second). The examiner-classified "Prior art keywords" are: nitrous oxide, valve means, fuel, pressure, control valve — consistent with the §102/§103 framing below.

Important scoping note: The two cited prior-art patents are both Ram Automotive Company documents — i.e., the applicant's own earlier family. Neither reference is directed to the inventive contribution of the '843 (the fail-safe vent). Both appear in the specification of the '843 as background: the '488 is cited as the exemplary "type of" nitrous oxide supply system, and the '140 is cited alongside it as related art.

2. Reference-by-reference analysis

Reference 1 — US 4,494,488 A

• Full citation: U.S. Patent No. 4,494,488, "Fuel charging system for high performance vehicles," Ram Automotive Company (assignee). Google Patents; FreePatentsOnline full text; USPTO PDF

• Dates: Filing/priority 1984-05-23; granted 1985-01-22. (Patented less than a year before the '843's 1985-08-13 §102(b) critical date, so it is available as §102(a)/(e) art and, on its face, as §102(b) art.)

• Brief description: Discloses a nitrous-oxide fuel-charging system of exactly the environment recited in the '843 preambles: a nitrous oxide supply cylinder 2 holding liquid N₂O at ~900 psi; a pressurized nitrogen blanket formed by a second cylinder 3 through a regulator 6 and an adapter 10 to drive the N₂O out at constant pressure; a nitrous oxide supply line 39 to a spray bar 43 on a base plate 41 between carburetor and intake manifold; a solenoid control valve 42 in line 39; and a separate fuel line 44 with its own solenoid control valve 45 feeding a fuel spray bar 46. Inventor credit per the earlier record is Wheatley (to be confirmed against the front page — I did not independently re-verify the inventor field in this pass).

• §102 claim mapping — honest assessment: This reference does not appear to anticipate any of claims 1–17 in full. It shows:

  • the preamble of claim 1 ("a supply of pressurized liquid nitrous oxide, means for spraying predetermined quantities of fuel and nitrous oxide into the vehicle engine, and control valve means for controlling the flow of nitrous oxide into the spray means");
  • elements (a), (b), (c) of claim 11 (pressurized liquid N₂O supply; injection means connected to the supply; first valve means controlling N₂O flow); and
  • the fuel-flow valve that is the added limitation of claim 17 (solenoid valve 45).

  What it lacks — and therefore why it cannot anticipate under §102 — is the entire point of the '843: there is no second/vent valve inversely slaved to the N₂O control valve (claim 1), no vent means communicating with the control valve (claim 11(d)), and no check valve between the control valve and the injection means for anti-reversion / low-pressure blocking (claims 2, 8, 11(e)). The '488's only venting is a pressure-relief valve 25 and overboard drain 28 for overpressure safety — a different function from the '843's leak-venting of a closed control valve.
  Net: at most a §103 "background/environment" reference and support for the Jepson-type preamble of claim 1; no §102 anticipation.

Reference 2 — US 4,572,140 A

• Full citation: U.S. Patent No. 4,572,140, "Nitrous oxide precooler," Ram Automotive Company, Canton, OH (assignee). Google Patents; Justia; OSTI 5835022; USPTO PDF

• Dates: Filing/priority 1984-10-09; granted 1986-02-25. (Granted after the '488 but before the '843 was filed 1986-08-13, so it is available as §102(a)/(e) and — by its 1984 filing — as §102(b) art.)

• Brief description: Discloses a precooler 15 for the same class of nitrous-oxide fuel-charging system. Elements: a nitrous oxide cylinder 10 (~900 psi); supply conduit 16 to a manifold 20; a solenoid actuated discharge valve 42 controlling flow of liquid N₂O through line 11 to spray bar 6; a second solenoid valve 45 that purges gaseous N₂O from conduit 16 through a purge line 47 into a cooling chamber 50 formed by a hose/jacket 23 around conduit 16; and an orifice block 32 at the far end discharging spent vapor. A fuel valve 7 feeds a separate spray bar 5. Co-inventor William M. Wheatley is one of the '843 inventors, so this is a same-family/same-inventor reference.

• §102 claim mapping — honest assessment: Also does not appear to anticipate any claim. Its structural overlap with the '843 lies in:

  • the claim 1 / claim 11 preamble (same class of N₂O supply + spray + control-valve system);
  • a purge/vent valve (45) that vents gaseous N₂O and, through orifice block 32, ultimately discharges it — superficially similar to the '843's vent valve 18, but critically different in kind and control logic: valve 45 purges into a closed cooling chamber to precool liquid N₂O before the main valve opens, and it is not inversely slaved to the main control valve to serve as a leak fail-safe;
  • a second valve (7) controlling fuel flow — relevant to claim 17.

  It contains no means placing a vent valve open when the control valve is closed (claim 1's core), no low-pressure one-way check valve at the spray-bar junction (claims 2, 8, 11(e)), and no fuel/oil-pressure switch interlocks (claims 5, 6, 9, 13–16). Net: no §102 anticipation.

Reference 3 — "Nitrous Charging by Ice," Internal Combustion Engineering (Tucson, AZ)

• Full citation: Article entitled "Nitrous Charging by Ice," published by/at Internal Combustion Engineering, Tucson, Arizona (as listed in the '843 USPTO citation record).
• Dates: Undated in the record; no publication date was given on the face of the USPTO citation list. As an unidentified-date trade publication it can only be relied on to the extent its date is established.
• Brief description: A trade-press/technical article on nitrous oxide "chemical supercharging" (charging the intake charge with N₂O, effectively an intercooling/oxidizer effect — hence "by ice"). It is background literature describing the general technique, not a specific apparatus.
• §102 mapping: A printed publication anticipates under §102(a)/(b) only if it discloses every element of a claim arranged as in the claim. I have no evidence it discloses the vent-valve/check-valve combination or any electrical interlock claimed here. No anticipation of any claim; background §102/§103 art at most.
• Uncertainty flag: I could not locate an authoritative dated copy or a bibliographic record for this item in this pass; treat its date and exact content as unverified. The only source for its existence is the USPTO citation list itself.

Reference 4 (and duplicate 5) — Superpower: Nitrous Oxide Injection, Pat Ganahl, 1977, p. 64

• Full citation: Pat Ganahl, Superpower: Nitrous Oxide Injection (S A Design Publishing Co., 1977), p. 64. Catalog corroboration: the Ohio Public INN-Reach library catalog lists Superpower: [a do-it-yourself guide to: turbocharging, supercharging, fuel-injection & nitrous-oxide], 1977 (catalog record).
• Date: 1977 — more than one year before the 1986-08-13 filing, so this is classic §102(b) art (printed publication in public use before the critical date).
• Brief description: A widely circulated do-it-yourself performance manual whose nitrous-oxide chapter covers installing N₂O injection on street/strip engines, including supply bottles, solenoids, nozzles/spray bars and fuel enrichment. Page 64 is cited as specifically relevant.
• §102 mapping: Because it is §102(b) art and predates the invention, it is eligible to anticipate — but a §102 anticipation requires the reference to disclose all claimed elements. p. 64 of a general DIY guide describing conventional N₂O injection would, at most, correspond to the claim 1 / claim 11 preamble (known N₂O injection systems). No anticipation of any claim; highly relevant §103 background art.
• Note on the duplicate: The list shows the Ganahl citation twice (once tagged "examiner," once "third party"). This is almost certainly a formatting artifact of the same citation appearing in both the examiner's and applicant's IDS, not two distinct references. No separate technical content.

3. Overall §102 conclusion

None of the two patent references or the non-patent literature appears to anticipate any of claims 1–17 of US 4,683,843 under 35 U.S.C. § 102.

• The two Ram Automotive patents ('488 and '140) disclose the environment (pressurized liquid N₂O supply, spray bars, solenoid N₂O control valve, separate fuel solenoid valve) that the '843 recites as admitted prior art in the preambles of claims 1 and 11, and supply the "third valve means … [controlling] the flow of fuel" recited in claim 17. They are best characterized as background/reference art (and would be argued under §103), not anticipatory art — neither shows the inverse-slaved vent valve of claim 1 or the anti-reversion, low-pressure-blocking check valve of claims 2/8/11(e).
• The non-patent literature (Ganahl 1977; "Nitrous Charging by Ice") describes the general technique of nitrous-oxide chemical supercharging. The Ganahl item is §102(b)-eligible by date but discloses only the conventional system, matching at most the claim preambles.
• Consequently, the novelty of the '843 resides entirely in the claimed improvement — (i) the claim 1 vent valve whose state is inverse to the main control valve, and (ii) the claim 11 combination of vent means + a downstream check valve that both reduces backflow and blocks sub-threshold-pressure N₂O from the injection means. Neither feature is disclosed by any cited reference, which is consistent with the patent having issued with 17 claims and no §102 rejection surviving on these references.

Direction of the art: The most probative later art that does build on (and cite) the '843 is the forward-citation set — e.g., US 5,267,275 (Rook), US 5,287,281 (Echlin), US 5,967,099 (Competition Cams), US 7,228,872 (Mills), US 8,550,866 (Wilson). These are not §102 prior art to the '843 (they post-date it) but are useful for prosecution-history/validity context, discussed in the earlier-generated summary.

4. Confidence and uncertainty

• High confidence: the identity and dates of US 4,494,488 and US 4,572,140, their assignee (Ram Automotive Company), and their technical content — sourced from Google Patents, FreePatentsOnline, Justia, and the USPTO PDFs.
• High confidence: the '843's cited-reference list contains exactly two patent citations and (at most) two distinct non-patent items, per the Google Patents "Patent Citations / Non-Patent Citations" fields.
• Medium confidence: the positive §102 rejection analysis (i.e., that none of the references anticipates). My mapping is based on the references' disclosed structures; a definitive opinion would require the actual examiner's PTO-892/office-action record, which I could not retrieve in this pass.
• Unverified: the existence, date, and content of the "Nitrous Charging by Ice" article (only source is the citation list), and the inventor field for the '488 (taken from the earlier-generated summary; not independently re-verified here).
• Flagged from the prior sections: the earlier summary's note that claim 9's recitation ("preventing the closing of said control valve means") appears internally inconsistent with the specification (low fuel/oil pressure should prevent opening/actuation) stands — I am reporting the claim text literally and not correcting it. This does not affect the §102 mapping above.

I'll build the §103 analysis on the prior art actually listed on this patent's page. Let me first pull the disclosing content of the two cited U.S. references and check the NPL.

Obviousness Analysis — U.S. Patent No. 4,683,843 under 35 U.S.C. § 103

Source of record: US4683843A on Google Patents (full text, claims, cited art, legal events). Prior-art set used below is the set actually listed in the "Patent Citations" / "Non-Patent Citations" fields of that page — i.e., the patent's own cited art, not third-party art I selected. I flag explicitly where I extend beyond that set to common knowledge, since that is a legitimate § 103 route but requires different evidentiary footing.

1. The two personnel of the analysis

Level of ordinary skill (PHOSITA). For a 1986 filing date in this art: a mechanical/automotive engineer (BSME or equivalent) with roughly 2–4 years' hands-on experience with aftermarket/racing fuel-charging and nitrous-oxide injection systems, or a racing-systems technician of comparable practical skill familiar with solenoid-controlled high-pressure (≈900 psi) N₂O delivery, spray-bar/base-plate induction hardware, and ordinary vehicle electrical interlocks. This level matters because essentially every non-N₂O-specific element in the claims (check valve, pressure switch, relay, series switch, in-cabin shutoff) is within the ordinary toolkit at that skill level.

Legal framework. Graham v. John Deere, 383 U.S. 1 (1966); KSR Int'l v. Teleflex, 550 U.S. 398 (2007) (predictable combinations of known elements; "obvious to try" where the field presents a finite number of identified, predictable solutions). Because this application was filed 1986-08-13, pre-AIA § 103 governs and § 103(c) (common-ownership exception) does not apply — a point of some significance here, because the two cited U.S. references are the patentee's own earlier patents.

2. The prior-art set and what each reference actually teaches

Key legal note on the two U.S. references: both are commonly owned by Ram Automotive and one (4,572,140) names William M. Wheatley, a co-inventor of the patent at issue. Under pre-AIA § 102(b)/§ 103, a patentee's own earlier patent is prior art against a later patent with a different inventive entity, and the 1986 filing predates § 103(c)'s common-ownership carve-out. So these are fully available § 103 references, and their shared assignee/same-field status is, if anything, an affirmative motivation-to-combine factor (common problem, common design language, common component vendors).

3. Independent Claim 1 — the crux

3.1 Element mapping

3.2 The obviousness case

Claim 1's sole inventive concept is inverse slaving of a leak-vent valve to the main N₂O control valve. That concept is not in the cited art. The § 103 case therefore rests on three legs, in ascending order of strength:

(a) The problem was known and admitted in the field. The specification itself concedes the leak-accumulation hazard was an existing, observed phenomenon: "These conditions have occurred in the past where the race driver is unaware of the failure of the nitrous oxide control valve and the accumulation of nitrous oxide in the engine." An admitted, known problem in the same art is a recognized source of motivation. Cf. KSR (design need/pressure in the field).

(b) The constituent techniques each pre-exist in the cited art.

• Overboard discharge of N₂O to a safe location — 4,494,488 (relief valve 25 → overboard drain 28 through the vehicle wall).
• Venting/purging N₂O to atmosphere as a routine step — acknowledged as prior practice in 4,572,140 ("heretofore … ejected into the atmosphere").
• Sequencing one solenoid relative to another in the same N₂O circuit — 4,572,140 (purge valve 45 opens before delivery valve 42; valve 42 has a time delay).
• Driver-compartment electrical control of the N₂O solenoids — 4,494,488 and 4,572,140 (switch 51).

(c) Fail-safe normally-open/normally-closed pairing is common knowledge. A normally-open vent valve energized closed by the same signal that energizes open a normally-closed supply valve is the canonical "de-energize-to-safe" pairing (the same logic as a normally-open bleeder in a double-block-and-bleed gas train, or a spring-return vent on an appliance gas valve). KSR squarely covers this: combining known elements according to known methods to yield predictable results, and using "a known technique to improve a similar device in the same way." The same electrical conductor that energizes valve 10 can energize valve 18 (the specification literally does this — relay 33 "will energize solenoid valves 10, 12 and 18 through conductor 38"), so the "means" limitation adds only conventional wiring.

Motivation to combine (articulable): A PHOSITA confronting the documented manifold-accumulation hazard, working in the same art, with an existing overboard-drain hardware precedent (4,494,488) and an existing second-solenoid-in-the-N₂O-line precedent (4,572,140), would see a small, finite set of predictable fixes: (i) add a check valve to keep leakage out of the manifold, and (ii) add a bleed/vent controlled inversely to the supply valve so leakage cannot accumulate. Both are within the ordinary skill level stated above.

3.3 Honest counterarguments (claim 1 is the patent's least vulnerable claim)

I do not think claim 1 is a slam dunk, for two reasons a patentee would press:

• Potential teaching away (4,572,140). That reference states the vapors "instead of … discharging … to the surrounding atmosphere … are returned into cooling chamber 50." Read broadly, this disfavors atmosphere-venting of N₂O. But the context is purge vapor during normal operation preceding a commanded injection, not leakage while the delivery valve is shut. The claimed vent performs its function only when the control valve is closed, so 4,572,140's preference does not reach the claimed situation. I rate this a real but survivable argument.
• Different function of 4,494,488's relief valve. Relief valve 25 has a preset opening near 950 psi — an over-pressure device, not a low-pressure leak-bleed device. A patentee will argue no reasonable expectation that a 950-psi relief valve suggests a leak-vent. The better reading is that it evidences the acceptability of overboard N₂O discharge, not the claimed function.

Assessment for Claim 1: probable rejection under § 103 over 4,494,488 + 4,572,140 + the known fail-safe vent-valve expedient, but this is the claim most worth defending (roughly a coin-flip to modest-obviousness/moderate-risk, depending on whether the factfinder accepts the teaching-away gloss on 4,572,140). No § 102 anticipation is available — neither reference discloses the inverse vent, and it is error to characterize claim 1 as anticipated.

4. Dependent claims 2–10 — a claim chart

These fall with progressively less effort; nearly all recite well-known expedients.

5. Independent claim 11 and claims 12–17

Claim 11 = supply + injection means + first valve + vent means + second valve between the first valve and the injection means that (i) reduces backflow from the injection means into the vent means and (ii) blocks low-pressure N₂O from entering the injection means. This is the same subject matter as claim 2 expressed independently. Its novelty over the art is the combination of (a) the inverse leak-vent and (b) a check valve at the junction. The check-valve half is the most ordinary of mechanical expedients (and its stated purpose — suppressing momentary reversion/back-pressure at initiation — is a well-understood line-charging phenomenon). Assessment: probable § 103 rejection; the combination is a "predictable variation" of the claim-1 combination.

6. Motivation to combine — consolidated

1. Same field of endeavor: all references are nitrous-oxide fuel-charging systems for high-performance/racing vehicles; two share the same assignee and a common inventor.
2. Same problem, expressly stated: N₂O leakage past a solenoid control valve accumulating in the intake manifold and causing a starting explosion (specification's own admission that this had "occurred in the past").
3. Known, finite solution set: prevent leakage from reaching the manifold (check valve) and/or remove leakage from the line (inverse vent). KSR "obvious to try."
4. Predictable results, no new principle: each added element performs exactly its known function (check valve blocks backflow; pressure switch opens/closes on pressure; relay switches solenoid current; series switch gates the circuit). KSR predictable-combination rationale.
5. Hardware precedent already in-house: overboard drain (4,494,488) and a second solenoid in the N₂O line with sequenced actuation (4,572,140).

7. Secondary considerations / rebuttal posture

• No evidence of nexus. There is no litigation, licensing, or commercial-success record for this patent that I could locate (see the prior Litigation section; the patent lapsed for nonpayment effective 1999-08-04). Any objective-indicia argument would still have to tie the success to the claimed inverse-vent feature rather than to the underlying N₂O racing boom.
• No unexpected result shown. The specification claims reduced "deficiency period," lean-mixture avoidance, and accident avoidance — all of which are the expected consequences of the recited elements, not evidence of nonobviousness.
• Strongest nonobviousness theory available to a patentee: the narrow teaching-away gloss on 4,572,140 discussed in § 3.3, plus the argument that no cited reference recognizes the inverse relationship between the two valves. This is the argument I would expect to carry claim 1, and possibly claim 11, over the cited art absent an additional § 103 reference.
• Litigation-grade caveat: to mount a certain § 103 attack, an attacker should add a reference or evidence of record establishing (a) normally-open vent valves slaved to normally-closed control valves as a known safety pattern, and (b) pressure-switch interlocks as of the mid-1980s. Neither is in the patent's cited-art list; both are, in my assessment, general knowledge at the stated skill level, but general knowledge must be proven (e.g., via textbook/industry-standard evidence), not merely asserted.

8. Bottom line

Flags and corrections to carry forward: (i) My prior section correctly notes there is no litigation/PTAB/CAFC record and that the patent lapsed 1999; that remains the case and reinforces the hypothetical nature of this § 103 exercise. (ii) The claim 9 internal inconsistency I flagged earlier (pressure valves preventing closing vs. opening) also carries a latent § 112(b) indefiniteness risk that would likely surface in any invalidity challenge alongside the § 103 grounds. (iii) I did not verify the page-level content of the two non-patent references; I have not attributed any specific claim element to them.