US 6223708

I'll search for information on this patent number.

US Patent 6,223,708 B1 — "Automatic Decompression System"

Note on identifiers: I interpreted "6223708" literally as US 6,223,708 B1 (granted publication of application US 09/254,579). No other number was substituted or corrected. My search did not surface any CAFC 2026 docket entry (or any litigation) involving this patent — see "Litigation status" below.

Bibliographic data

Source: https://patents.google.com/patent/US6223708/en (retrieved 2026-04-26 per this session).

Abstract (as printed)

The abstract describes an automatic decompression system for an internal combustion engine, especially a one-cylinder diesel, having at least one outlet and one inlet valve actuated by a camshaft with at least one cam. The outlet valve is lifted during starting to reduce cranking resistance. A fully automatic lifting device, engaging in the outlet-valve cam, lifts the valve at speeds below a "switching speed." The lifting device uses a bow-shaped member pivoted in articulated relationship between the cam and a cam disk, having two articulated arms and a crosspiece joining them. Below the switching speed, the bow-shaped member occupies an engaged decompression position projecting beyond the cam base circle; at the switching speed it can disengage into a neutral position in the cam-disk plane. Speed-dependent control is provided by at least one flyweight biased radially inward by a spring and flexibly coupled to the bow-shaped member.

Plain-language overview of the independent claims

The patent has 11 claims. Claim 1 is the only independent claim; claims 2–11 all depend, directly or indirectly, from claim 1 (claim 11 depends from claim 10).

Claim 1 — the core system

A fully automatic decompression system for an internal combustion engine having at least one outlet valve and at least one inlet valve driven by a camshaft with at least one cam. The outlet valve is lifted off its seat during starting to reduce cranking resistance. Elements:

1. A fully automatic lifting device that lifts the outlet valve at engine speeds below a switching speed (the changeover between decompression and compression), engaging directly in the outlet-valve cam.
2. A bow-shaped member — pivoted in articulated relationship and located between the cam and a cam disk — having two articulated arms (pivoted at points in a radial plane of the cam disk) joined by a crosspiece.
3. Below the switching speed: the bow-shaped member sits in the cam plane in an engaged decompression position, projecting beyond the cam base circle. At the switching speed: it can disengage into a neutral position in the cam-disk plane.
4. At least one flyweight, coupled to the bow-shaped member and biased radially by a spring, controls engagement/disengagement based on engine speed.

In short: a centrifugal, spring-loaded flyweight automatically swings a bow-shaped lever in and out of the cam path, adding a small extra valve lift at low RPM to ease starting, and withdrawing automatically once the engine spins fast enough.

Dependent claims (grouped for convenience)

• Claim 2 — the flyweight is coupled to the bow-shaped member via a ramp formed on the flyweight's internal radius, working against a disengaging spring (corresponds to the FIG. 7 embodiment, element 71/77).
• Claim 3 — the flyweight is coupled to the bow-shaped member through a driver on an articulated arm (FIG. 1–5 embodiment, driver 10 / driving arm 9).
• Claim 4 — two bow-shaped flyweights connected to each other by a joint (elements 3, 6, joint 8), which cancels gravitational effects and permits very low switching speeds.
• Claim 5 — decompression lift occurs over a crank-angle range of approximately 90°, set by the arc length of the bow-shaped member.
• Claim 6 — the switching speed is between 300 and 600 rpm (specification prefers ~400 rpm).
• Claim 7 — the control cam has a slot to receive the bow-shaped member in its engaged position (position retention and deformation protection).
• Claim 8 — the inlet valve is actuated by the same cam as the outlet valve and is additionally lifted during the decompression phase, in the direction of camshaft rotation after the outlet valve.
• Claim 9 — the outlet valve closes 40° before ignition TDC and the inlet valve opens 40° past ignition TDC.
• Claim 10 — a valve-dragging lever is provided between the cam and the valve (acting directly or via a tappet rod).
• Claim 11 (depends on 10) — the valve-dragging lever is liftable by 0.2 mm to 0.6 mm by the lifting device (specification prefers 0.4 mm; valve lift becomes 0.3–0.8 mm depending on movement ratio).

Litigation / CAFC 2026 status

• No CAFC 2026 docket, appeal, or other litigation involving US 6,223,708 was found in my searches. I cannot confirm any such docket exists. This is a plausible negative for a 2001 patent that lapsed in 2009 for non-payment of maintenance fees (37 CFR 1.362), well beyond the enforceability window of interest.
• I want to be explicit about the limits here: I do not have direct, authoritative access to the CAFC docket system or USPTO Patent Center in this session, and my searches returned irrelevant "similar-number" noise (e.g., other patents, an unrelated UPC matter, Hong Kong journal entries) rather than any docket for this patent. Treat the "no litigation" finding as an absence of evidence, not as certified proof.

Prior art cited on the face (brief)

Notable references include FR 2,522,725 A1 (Bernard Moteurs), US 4,615,313 A (Kawasaki), US 4,590,905 A (Honda), EP 0 167 691 A2 (Fuji Jukogyo), JPS 63-306215 A (Honda), US 5,301,643 A (Briggs & Stratton), JPH 09-184410 A (Honda), and US 5,706,769 A (Honda — OHC engine). The specification also distinguishes European Patent EP 0515183 A1 as a centrifugal starting aid suffering from excessive installation-space requirements due to a rigid flyweight-to-bow connection — stated as the motivation for the present invention.

Confidence note: The title, assignee, inventors, dates, abstract, and claim set above are drawn from the full authoritative patent text supplied in this session and are high-confidence. My findings on litigation/docketing are low-confidence negatives — I did not locate a CAFC 2026 docket, but I also cannot rule one out with authoritative docket source access.

I'll search litigation-focused sources for this specific patent number.

Let me search more targeted litigation databases.

Let me try a few more authoritative litigation-specific searches.

Litigation Search: US Patent 6,223,708 (US 6223708)

Result: No known litigation found

After running multiple targeted searches across litigation-oriented sources, I found no litigation — no district court infringement action, no declaratory judgment action, no CAFC appeal, and no PTAB/IPR proceeding — involving US Patent 6,223,708 ("Automatic decompression system," Motorenfabrik Hatz GmbH & Co. KG). There is therefore no case to list with plaintiff, defendant, jurisdiction, case number, filing date, or outcome.

What I searched and what came back

Why this negative is consistent with the patent's record

1. The patent lapsed early. Per the authoritative record, maintenance fees were not paid; the patent expired due to nonpayment under 37 CFR 1.362, effective 2009-05-01 (LAPS/STCH/FP legal events). A patent that lapsed in 2009 could not have supported infringement claims for most of the 17-year-plus window since.
2. Priority date 1996-09-11 (DE 19636811C2) — the enforceable term ran well before the current 2026 period of interest.
3. Niche subject matter. The claimed subject matter is a mechanical centrifugal decompression system for small single-cylinder diesel engines — a low-litigation-value space dominated by small-engine makers (Briggs & Stratton, Tecumseh, Honda, Kawasaki, MTD). The patent's "Cited By" and "Family Cites" lists show subsequent patent activity (e.g., Briggs & Stratton's US 6,539,906; US 6,837,203 to MTD; US 10,400,640 to BMW) — but follow-on patent citations are not litigation and should not be reported as such.

Important caveats (stated explicitly)

• This is an absence of evidence, not certified proof of absence. I do not have direct authenticated access to PACER, the CAFC docket, the USPTO Patent Center litigation records, or the Unified Patents litigation portal in this session; my searches returned general web results rather than a queried litigation database.
• A search limitation is relevant: results were dominated by "similar number" noise — notably the '223 patents in Tegal/Tokyo Electron, MV3 v. Roku, 3M v. Berwick (a decorative-bow patent whose specification uses "bow," "crosspiece," and "arms," which coincide with US 6,223,708's own claim vocabulary). These are different patents and must not be confused with US 6,223,708. Per the operating rule to interpret identifiers literally, I did not substitute or merge any of these.
• If authoritative confirmation is needed, the definitive checks would be a PACER "party/patent" search and a USPTO Patent Center "Litigation" tab lookup for Patent No. 6,223,708 — neither of which I can execute directly here.

Bottom line

No litigation is known for US Patent 6,223,708. I found no case to populate the requested fields (plaintiff, defendant, jurisdiction, case number, filing date, status). Given the patent's 2009 fee lapse and 1996 priority date, the absence of litigation is expected. I flag this as a low-confidence negative because I could not query an authoritative docket source directly.

I'll verify the structured "no proceedings" finding with targeted searches before finalizing.

Proceedings overview

Total AIA trial proceedings on US 6,223,708: zero (0). Breakdown by status: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The structured "PTAB proceedings on file" block — sourced from the USPTO Open Data Portal, which is the canonical list — returns no IPR, PGR, or CBM for this patent, and my independent web searches did not surface any proceeding number, petition, institution decision, Final Written Decision, or appeal tying this patent to the Board.

The bottom-line defensive posture is not "hardened patent" and not "troll with dead claims" — it is "no IPR battlefield exists because there was never a fight worth funding." US 6,223,708 issued 2001-05-01, lapsed for non-payment of maintenance fees effective 2009-05-01 (37 CFR 1.362), and was already past its 20-year term horizon before AIA trial practice matured into a standard defense tool. Any demand letter built on this patent faces a far cheaper dispositive argument than an IPR: the patent is expired, the fee lapse is on the public record, and the § 286 six-year damages lookback window for pre-lapse infringement closed years ago. A defendant should not be budgeting for a PTAB petition here — it should be budgeting for a two-page motion.

No proceedings on file

No per-proceeding sections follow, because there is nothing to report. Stating that explicitly, per the constraint against fabrication:

Verification performed

• Canonical source: the structured "PTAB proceedings on file" block in this prompt (USPTO ODP ingest) returns no AIA trial proceedings. This is the authoritative list and it is controlling.
• Independent searches run 2026-09-22 for the patent number, the assignee (Motorenfabrik Hatz GmbH & Co. KG), and the subject matter ("decompression," "bow-shaped member," "flyweight") against PTAB petition and decision text. Results returned unrelated proceedings concerning other patents — e.g., an IPR of U.S. Pat. 7,537,370, IPR2017-01872 against U.S. Pat. 6,103,611, IPR2017-00858 against U.S. Pat. 9,289,688 — and no Hatz/Motorenfabrik docket. The only hits tying "Hatz" to a patent document concerned an unrelated European patent (EP 2,156,040, engine mounting) and its Czech national-phase record.
• Cross-check with the previously generated section: the litigation/CAFC finding there was "no CAFC 2026 docket, appeal, or other litigation" for this patent, flagged as a low-confidence negative. My PTAB finding is consistent with and independently reinforces that. There is no contradiction between sections.

Confidence caveat (stated as required)

This is a strong-but-not-certified negative. I do not have direct authenticated access to PTAB E2E or to the full PTAB API in this session; my searches returned generic PTAB corpus text rather than a docket for this patent. A pre-AIA-era, 2009-lapsed patent on a niche single-cylinder diesel starting aid is precisely the profile that should generate zero AIA trials, so the absence is expected rather than surprising — but treat it as absence of evidence, verified against the best structured source available, rather than as a notarized null. If you need certainty, pull the patent's complete prosecution and review history in PTAB E2E and the USPTO PTAB Decisions database, and search CourtListener for any appellate activity.

Data-quality flag (non-substantive)

Two anomalies in the machine-readable record around this patent, noted so you don't chase them:

1. The Google Patents "Patent Citations" table lists EP 0515182 A1 (Samsung Semiconductor, "Low-power crystal circuit," priority 1991-05-23) as a cited reference. The specification, however, distinguishes EP 0515183 A1 as the centrifugal starting aid whose rigid flyweight-to-bow connection motivated the invention. EP 0 515 182 and EP 0 515 183 are adjacent serial numbers in the same 1992 publication batch but different documents and different subject matter — the Samsung crystal-circuit entry in the citation table appears to be an unrelated reference or a data artifact.
2. Claim 1 as issued recites changeover "from compression to decompression," while the abstract and specification consistently describe changeover "from decompression to compression." The earlier summary reproduces claim 1 verbatim, which is correct. If an IPR had ever been filed, this claim/specification mismatch would have been a § 112 indefiniteness or claim-construction target.

Strategic summary

Claim status: all 11 claims UNTESTED, and the untested status is now permanent and mostly irrelevant. No claim of US 6,223,708 has been canceled, confirmed, or construed by the Board — not claim 1, not dependent claims 2–11. There is no surviving-claims list to report because no claim was ever administratively challenged. The practical consequence: an assertion targeting claims 1–11 cannot be answered with "the PTAB already killed that claim." The answer has to be built on other grounds — expiration, the fee lapse, § 286 damages timing, and invalidity in district court under §§ 102/103/112 using the art already of record.

Estoppel landscape: § 315(e)(2) is a non-issue, because no IPR was ever instituted. With no petitioner and no institution, there is no party carrying § 315(e)(2) estoppel and no ground that a petitioner "raised or reasonably could have raised." The corollary cuts the other way for a defendant: because no AIA trial occurred, the entire prior-art universe remains available in a district court or ITU invalidity defense, unconstrained by IPR estoppel or by the Board's narrower § 102/103-only grounds. The on-face references remain fair game, including FR 2,522,725 A1 (Bernard Moteurs), US 4,615,313 A (Kawasaki), US 4,590,905 A (Honda), EP 0 167 691 A2 (Fuji Jukogyo), JPS 63-306215 A (Honda), US 5,301,643 A (Briggs & Stratton), JPH 09-184410 A (Honda), and US 5,706,769 A (Honda), plus the family-cited US 5,150,674 A (Briggs & Stratton, "Centrifugally responsive compression release mechanism") and the specification-distinguished EP 0 515 183 A1. Note the art is thin and old — the cited references cluster in the 1982–1998 window, which is what you would expect for a 1996-priority mechanical starting aid.

Pattern signals: none of the usual markers are present. No serial petitioner (no repeat filer, no Unified Patents or other defensive aggregator in the chain); no patent owner aggressively appealing Board outcomes, because there are no outcomes; no parallel ITC or district court track surfaced in my searches or in the earlier litigation section. The patent's public trajectory is a single story: German priority DE 19636811 (1996-09-11) → PCT/EP1997/004799 → US national stage → grant 2001-05-01 → four-year maintenance fee paid 2004-10-10 → lapse 2009-05-01. That is the profile of a patent that was maintained just long enough to cover a product-generation cycle and then abandoned. Eight U.S. publications cite it as prior art or background (Briggs & Stratton, Tecumseh, MTD, Honda, BMW, Renault among them), which confirms technical relevance but not commercial assertion.

One cross-section note: the earlier section asks whether a "CAFC 2026 docket" exists and correctly answers no. My finding supplies the structural reason: a Federal Circuit appeal of a PTAB decision is impossible here, because there is no PTAB decision. There is no contradiction to flag — the two sections agree.

Recommended next steps

1. If you have received a demand or complaint citing US 6,223,708, do not file an IPR. It is the wrong tool. The patent lapsed for non-payment of maintenance fees effective 2009-05-01, per the Legal Events record (LAPS 2009-05-01; STCH 2009-06-01; FP 2009-06-23) on Google Patents. An expired patent cannot support ongoing infringement, and the § 286 six-year damages lookback has long since run past the lapse date. Lead with that.
2. Verify the lapse in the authoritative USPTO record — do not rely on Google Patents for a dispositive defense. Pull the fee history and the maintenance-fee status in USPTO Patent Center for application 09/254,579, and confirm the 2009-05-01 lapse date and the absence of any petition to revive or late payment. A revived patent changes the analysis and must be checked, not assumed.
3. If the patent were somehow revived or the lapse contested, the invalidity defense is unconstrained. Because no IPR exists, no § 315(e)(2) estoppel applies to anyone. Assemble the § 102/103 case from the on-face references and US 5,150,674 A, and consider the § 112 angle on the claim 1 "compression to decompression" versus specification "decompression to compression" mismatch noted above — that inconsistency is worth a claim-construction position in district court even though no Board ever reached it.
4. Do not represent to a court or adversary that a PTAB proceeding exists. There is none. If opposing counsel suggests otherwise, request the proceeding number and check it in PTAB E2E — no number will be forthcoming, and you should treat any assertion of a docket as unverified until then.
5. Confirm the negative yourself for the record. Search USPTO PTAB Decisions and CourtListener for the patent number, and retain the printouts as a diligence exhibit. The absence of PTAB activity on a well-cited, 2001-issued patent is itself the signal: this patent was never worth attacking, which strongly suggests it was never worth asserting.

Format note: all proceeding fields above that would ordinarily carry a proceeding number, judge panel, institution date, FWD disposition, settlement terms, and appeal docket are marked "None found" rather than populated, because inventing any of those values would violate the no-fabrication constraint. No proceeding number appears in this report because none exists.

I'll research the ownership chain and the original assignee's status before assembling the record.

Let me try to pin down the recorded assignment details and the correspondent of record.

Ownership reconstruction — US 6,223,708 B1 (Kampichler / Griebl, "Automatic decompression system")

Sourcing note up front (important): I could not open assignmentcenter.uspto.gov directly from this session, so I reconstructed the chain from the USPTO assignment data as mirrored in the Google Patents "Legal Events" record for this patent, cross-checked against a parallel Hatz assignment record indexed on PlainSite and against the EPO bibliographic data for the same family (EP 0 925 427 B1). Where I am inferring rather than reading a record, I say so. The authoritative verification links are given in the Verdict section.

Inventors

Named-inventor pattern: No anomaly. This is the classic employee-inventor → employer assignment fact pattern: both inventors are German residents living in the immediate vicinity of the assignee's plant, both assign to Hatz within roughly two years of the 1996 priority filing, and the senior inventor has a long multi-patent career at the same company. There is no evidence of inventors departing the original assignee within 12 months of filing, and no evidence of individual inventors retaining or later re-acquiring rights. Note the assignment history includes a corrective assignment to fix the first inventor's name (see timeline), which is a clerical correction, not a change of inventorship.

Original assignee

Motorenfabrik Hatz GmbH & Co. KG (Ruhstorf an der Rott, Lower Bavaria, Germany) — the entity named on the face of the issued patent and the current assignee per the USPTO record.

• Primary line of business: design and manufacture of 1- to 4-cylinder air- and liquid-cooled industrial diesel engines (1.5–64 kW), plus engine-driven systems (pumps, generator sets, marine/military packages) and precision metal components. Founded 1880 by Mathias Hatz; engine building since 1904. Family-owned, independent, ~700–1,060 employees worldwide, revenue on the order of €150M (2012 figure). Source: hatz.com — Company; Hatz on Wikipedia.
• Did they ship a product embodying the claims? — Yes. Hatz's marketing material for the B-series and D-series single-cylinder mechanically-governed diesels states that injection pump and valve actuation are driven by the patented SCS (Single Cam System), which "requires only a single cam and moreover includes automatic decompression" ("das lediglich einen einzigen Nocken erfordert und zudem eine Dekompressionsautomatik beinhaltet") — Hatz brochure line-up 2025, DE. That is precisely claim 8 (inlet valve actuated via the same cam as the outlet valve) plus the claim 1 lifting device. Hatz engines are also marketed on their sub-zero starting behaviour, consistent with the stated purpose of the patent.
• Current status: Operating, independently owned, still headquartered at Ruhstorf. Two corporate events are worth noting but are not relevant to this patent: (i) the components business was spun off into Hatz Components GmbH in late 2021, with Berylls Group acquiring a majority stake — credit report summary; (ii) a separate Swiss distribution affiliate, Motorenfabrik Hatz AG (Altendorf, CH), went into liquidation and was deleted from the Swiss commercial register on 2021-07-21 — Moneyhouse. Neither is the owner of this US patent, and by 2021 the patent had already been lapsed for twelve years.
• Patent-status context: US 6,223,708 was allowed to lapse for non-payment of maintenance fees effective 2009-05-01 (37 CFR 1.362), i.e. it was enforceable only from issue (2001-05-01) to mid-2009. Its natural expiry would have been 2017-09-04 (20 years from the PCT filing date).

Assignment timeline

Two recorded assignments exist for US 09/254,579 / US 6,223,708 B1. Both are assignments by the inventors to the original operating-company assignee. There are no post-issuance recordings of any kind — no security agreements, no mergers, no change-of-name, no transfers to any third party.

• 1999-01-11 (effective) / recorded 1999-03-10 — Reel 009924/0915

  • Conveyance: Assignment (Assignment of Assignors' Interest)
  • Assignor: Kampichler, Guenter; Griebl, Udo
  • Assignee: Motorenfabrik Hatz GmbH & Co., KG (Germany)
  • Correspondent: Not stated in the machine-readable assignment event I could access. Inferred (not confirmed) to be Aaron B. Karas, Helfgott & Karas, PC, Empire State Building, 60th Floor, New York, NY 10118 — that firm is the named correspondent on a directly parallel Hatz recording, USPTO Patent Assignment Reel 9483/652, an "Assignment of Assignors' Interest" from Kampichler & Eder to Motorenfabrik Hatz covering US 6,076,494, executed 1998-07-29 and recorded 1998-08-13 (PlainSite record). Same assignee, same inventor pool, same filing window. Flag: if this inference holds, Helfgott & Karas is the recurring US recording correspondent for Hatz's 1998–1999 filings. That is operating-company patent counsel, not an NPE agent — a benign recurrence.
  • Context: Original employment/ownership assignment. This is the link that took the invention from the two individual inventors to the German engine manufacturer, executed just before/around the US national-stage entry (application 09/254,579) of PCT/EP1997/004799.

• 1999-01-11 (effective) / recorded 1999-08-30 — Reel 010243/0280

  • Conveyance: Assignment — expressly styled a Corrective Assignment: "CORRECTIVE ASSIGNMENT TO CORRECT FIRST INVENTOR'S NAME AT REEL 9924, FRAME 0915."
  • Assignor: Kampichler, Guenter; Griebl, Udo
  • Assignee: Motorenfabrik Hatz GmbH & Co. KG
  • Correspondent: Same inference as above (not stated in the event data).
  • Context: Change of name / clerical correction only. Not a transfer of ownership — it re-records the same conveyance to fix a misspelling of the first inventor's name (compare the EPO record, which spells the inventor "KAMPICHLER, Günter," and the German priority, which lists "KAMPICHLER GUENTER; GRIEBL UDO"). No new consideration, no new assignee.

Parallel family record (for completeness, not a US assignment): the European member of the family, EP 0 925 427 B1, names Motorenfabrik Hatz GmbH & Co. KG as patent proprietor (73) and Grättinger & Partner (GbR), Postfach 16 55, 82306 Starnberg, DE as representative of record (74) — the firm Hatz uses for EPO prosecution (it also appears on EP 0 688 397). That is EPO representation, not a US recording correspondent, and no ownership transfer is reflected.

If the Assignment Center shows no further records — it does not. Records exist (the two above), and the absence of anything after 1999 is itself the finding: the original assignee never parted with the patent.

Timeline diagram

timeline
    title Ownership of US 6223708
    1996 : DE priority application filed 1996-09-11
    1997 : PCT application filed 1997-09-04
    1999 : Inventors assign to Motorenfabrik Hatz
         : Corrective assignment fixes inventor name
    2001 : US patent 6223708 issued 2001-05-01
    2009 : Patent lapses for unpaid maintenance fees

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. The only recorded assignee in the entire chain is Motorenfabrik Hatz GmbH & Co. KG itself (Reels 009924/0915 and 010243/0280). There is no licensing-only LLC, no "IP/Holdings/Ventures" suffix, no registered-agent service address. The assignee address of record is the operating plant (Ernst-Hatz-Str. 16, 94099 Ruhstorf a.d. Rott, DE).

2. Known asserter in the chain — NOT PRESENT. Neither assignor nor assignee matches any entity on the NPE lists provided (Acacia, Marathon, IV, IPNav, Wi-LAN, Converso/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, Spangenberg entities). Hatz is a 145-year-old family-owned engine manufacturer, not a licensing vehicle. I found no RPX/Unified Patents listing for this patent or for Hatz as an asserter.

3. Repeat correspondent across the chain — UNCLEAR (and benign if true). Two recordings five-and-a-half months apart were filed by the same assignee's US patent counsel — Hatz's own outside counsel against whom I can only offer an inference. The machine-readable assignment events do not expose the correspondent field, and the strongest evidence for a name is the parallel Hatz assignment at Reel 9483/652 (correspondent Aaron B. Karas, Helfgott & Karas, PC, New York), which covers a different Hatz patent but the same assignee and the same inventor. I mark this unclear, and stress that even if confirmed, recurrence by an operating company's own prosecution firm across two of its own employee-assignment recordings is not the NPE tell described in this signal (which looks for one attorney running a family of unrelated-looking shell LLCs). Here the assignee never changes, so there is no shell to hide behind.

4. Cascading transfers — NOT PRESENT. Only two recordings exist, both to the same assignee, both with the same effective date (1999-01-11), and the second is a name correction of the first. There is no chain of LLCs, no sub-24-month sequence of distinct assignees, no shared correspondent address across different owners.

5. Pre-litigation transfer — NOT PRESENT. No infringement suit naming US 6,223,708 was located (consistent with the prior section's finding of no CAFC/litigation activity). Both recordings predate issuance by ~2 years and predate any conceivable assertion by a decade. There is no transfer within 6 months of a suit because there is no suit and no transfer.

6. Bankruptcy fire-sale — NOT PRESENT. Hatz has not filed for bankruptcy, and no assignment out of Hatz exists. The only insolvency-flavoured datum in my search is the Swiss sales affiliate Motorenfabrik Hatz AG in Liquidation (deleted from the Schwyz register 2021-07-21), which never held this US patent and which was wound up 12 years after the US patent lapsed. Not a fire-sale signal.

7. Privateering — NOT PRESENT. No transfer to an NPE asserting on Hatz's behalf; no SEC filing, Patent Progress, or EFF coverage of any such arrangement involving this patent.

8. Defensive aggregator (anti-NPE) — NOT PRESENT. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. It terminates where it started.

Verdict

Insufficient data (only the original assignment).

The chain consists solely of the two 1999 recordings — Reel 009924/0915 (recorded 1999-03-10) and its corrective re-record Reel 010243/0280 (recorded 1999-08-30) — both conveying the inventors' rights to Motorenfabrik Hatz GmbH & Co. KG, the operating manufacturer that then shipped the invention in its B/D-series single-cam diesel engines. There is no post-issuance assignment of any kind, no security interest, no third-party buyer, and no litigation; the patent simply lapsed for unpaid maintenance fees on 2009-05-01, so the chain has been frozen at a single owner for its entire enforceable life. All eight NPE signals are negative or unclear, with zero positive signals — this is a clean employee-invention-to-operating-company ownership record, not an assertion vehicle, and I found no evidence to support any NPE characterisation.

Verification links:

• USPTO Assignment Center (search "6223708" or application "09/254,579"): https://assignmentcenter.uspto.gov/
• Google Patents legal events (mirror of the USPTO assignment data cited above): https://patents.google.com/patent/US6223708/en#legal-events
• Parallel Hatz recording showing the likely correspondent firm (Reel 9483/652): https://www.plainsite.org/patents/assignment.html?id=[1585207](/patent/1585207)

Confidence: High confidence in the existence, dates, reel/frame numbers, conveyance types, and parties of the two recordings (drawn from the USPTO-derived legal-events record supplied in this session and cross-checked against the EPO family record). Lower confidence on the correspondent name — it is an inference from the parallel Hatz assignment of 1998-08-13, not a direct read of the correspondent field on Reels 009924/0915 or 010243/0280, which I could not retrieve. No CAFC 2026 docket or other litigation appears in the record; treat that as an absence of evidence rather than certified proof.

I'll verify the patent and dig into each cited reference. Let me run targeted searches.

Good data. Let me verify the remaining cited references and the EP 0515182/0515183 discrepancy.

Prior-Art Analysis — US 6,223,708 B1 ("Automatic decompression system")

1. Record confirmation (USPTO data as mirrored)

The number 6223708 resolves, literally and unambiguously, to US 6,223,708 B1, granted 2001-05-01 on Application US 09/254,579 (national-stage entry of PCT/EP1997/004799), applicant/assignee Motorenfabrik Hatz GmbH & Co. KG, inventors Guenter Kampichler and Udo Griebl, earliest priority DE 19636811, 1996-09-11. Source: https://patents.google.com/patent/US6223708/en and https://www.freepatentsonline.com/6223708.html.

No similar-number substitution has been made. Two bookkeeping notes before the substance:

• Date inconsistency in the session materials: the system date is 2026-09-22, while the task header states "Current Date: April 26, 2026" and the prior sections record a retrieval of "2026-04-26." This does not affect the patent data (which is a 2001 grant), but the date stamps in the file are not self-consistent.
• I could not execute a direct query against USPTO Patent Center / PATENTSCOPE / PACER in this session. My bibliographic and citation data come from the authoritative full text supplied in this session plus the Google Patents mirror of the USPTO record. Where I rely on the reference disclosures rather than just their front-page data, I identify the source and my confidence.

2. Methodology and the §102 threshold that actually governs here

Two things control this analysis, and they cut heavily against finding true anticipation:

(a) Every claim 2–11 depends from claim 1. Claim 1 is the only independent claim; claim 11 depends from claim 10, which depends from claim 1. Therefore a reference can only anticipate claims 2–11 under §102 if it also discloses every element of claim 1. Almost all of the face-cited art discloses the centrifugal decompression concept while missing one or more structural elements of claim 1 (the "bow-shaped member," the "two articulated arms pivoted at points in a radial plane of the cam disk … connected by a crosspiece," and the "cam plane → cam-disk plane" changeover), plus the spring-biased flyweight. That makes the cited art natural §103 material, not clean §102 material — a distinction the request asks me to observe.

(b) Anticipation requires the elements "arranged as in the claim." Several references disclose the individual pieces (an auxiliary cam that projects beyond the base circle; a U-shaped or yoke-like member; flyweights; a recess to receive the member when disengaged). None that I could read discloses the specific articulated bow geometry between cam and cam disk, engaged in the cam plane and disengaged into the cam-disk plane, together with a radially spring-biased flyweight.

Confidence convention used below: High = I read the reference disclosure or verified bibliographic data; Medium = title/abstract and secondary sources; Low = bibliographic only.

3. Citations of record for US 6,223,708 (9 references)

Family-cited reference (appears in "Family Cites Families," not the US face list):

Reference expressly discussed in the patent's own specification (acknowledged prior art):

4. Reference-by-reference §102 assessment

4.1 The closest art: US 5,150,674 / EP 0 515 183 A1 (Briggs & Stratton)

This is the only cited/acknowledged reference whose structure maps closely onto claim 1's vocabulary at the element level:

• "bow-shaped member … two articulated arms … connected by a crosspiece" ↔ the U-shaped yoke, first and second legs, curved saddle;
• "projects beyond the cam base circle" ↔ the auxiliary cam member on the saddle engaging the cam follower at cranking speed;
• "neutral position" ↔ the portion of the member received in the camshaft recess when disengaged;
• "flyweight coupled to the bow-shaped member" ↔ the pair of flyweights that pivot the member.

Why it likely still is not clean §102 anticipation of claim 1: (i) the disclosure states the member is designed to be retained "without an additional spring or a separate pivot pin," whereas claim 1 affirmatively requires a flyweight "biased by a spring in a radial direction"; (ii) the member is pivoted on the camshaft itself rather than being "disposed between the at least one cam and a cam disk" with disengagement "into the cam-disk plane"; and (iii) the Hatz specification characterizes the reference as having a rigid flyweight-to-member connection. Those are exactly the differences the patentee articulates as the inventive contribution. Assessment: high-value §103 reference (the primary obviousness reference), and the strongest §102 candidate for claim 7 (receiving slot/recess) and claim 1's structural core — but not a confident full-claim-1 anticipation.

4.2 US 4,615,313 A (Kawasaki) — strongest §102 candidate for claim 4

The disclosure (verified at https://patents.google.com/patent/US4615313 and https://www.freepatentsonline.com/[4615313](/patent/4615313).html) recites a first centrifugal weight pivoted on the holder and a second centrifugal weight pivoted on the first weight about a second pin — i.e., two articulated weights joined at a joint, with a spring between them and a cam structure that projects beyond the cam contour at low speed and retracts at high speed. Claim 4 ("two bow-shaped flyweights … connected to each other by a joint") reads almost literally onto this, and claim 1's "cam disk" plausibly reads onto Kawasaki's discal holder fixed to the camshaft end. The weakness for full claim 1 anticipation is the absence of a member having "two articulated arms … connected by a crosspiece," the projecting element being a cylindrical pillar, not a crosspiece bridging two arms. Assessment: §102 exposure for claim 4 is arguable but real; for claim 1 it is §103.

4.3 US 4,590,905 A (Honda) — strongest §102 candidate for claim 6

Claim 6 recites a switching speed "between 300 and 600 rpm." Honda's '905 expressly discloses changeover from decompression to compression "in the comparatively low engine speed range of about 600 r.p.m.," and re-engagement at about 1100 rpm on deceleration. A claimed range whose endpoint is expressly disclosed is a classic §102/§103 battleground (anticipation if the reference discloses the range "at the endpoint," otherwise obviousness). The reference also discloses plural weights (6, 6′, 9) relevant to claim 4 and the generic flyweight-plus-spring control of claim 1. Assessment: notable §102(b)/§103 exposure for claim 6; §103 for claims 1 and 4.

4.4 FR 2,522,725 A1 (Bernard Moteurs)

The verified abstract discloses a lever sliding in translation within an internal axial camshaft groove, with a retractable stop actuated by a flyweight guided on a rotating support against elastic return force. This is a translation mechanism, not a pivoted bow-shaped member, and it lacks the cam-disk-plane neutral position. Assessment: relevant to claim 1's flyweight/spring/automatic changeover elements only; §103, not §102.

4.5 US 5,301,643 A (Briggs & Stratton)

The reference is directed to using an existing compression-release as the actuating element of a low-oil sensor. It may disclose compression-release hardware generally, but it does not disclose the claimed lifting device geometry, and its purpose is antithetical to claim 1's stated cranking-resistance-reduction purpose. Assessment: background art; no realistic §102 anticipation of any claim.

4.6 The Honda family (JPS 63-306215 A; JPH 09-184410 A; US 5,706,769 A)

These three are engine decompression / OHC engine references. They are most useful against:

• claim 10 (valve-dragging lever between cam and valve) — the cited art uses tappets/cam followers and rocker arrangements throughout (e.g., US 4,615,313 expressly refers to lifting "a valve operating member, such as a tappet");
• claim 8 (inlet valve actuated by the same cam as the outlet valve, lifted after the outlet valve) — relevant to cam/valve-train architecture.
  I was unable to read the full disclosures of JPS 63-306215 A and US 5,706,769 A in this session, so I flag these mappings as provisional rather than concluded.

4.7 EP 0 167 691 A2 (Fuji Jukogyo)

Bibliographic match confirmed (1984-07-10 / 1986-01-15, "Decompression apparatus for engines"). I could not retrieve the disclosure text; treated as decompression-apparatus background art. Mapping provisional (Low confidence).

4.8 EP 0 515 182 A1 (Samsung Semiconductor) — flagged

As listed in the record, this is a semiconductor crystal-oscillator circuit, with no discernible relation to engine decompression. It shares a publication date (1992-11-25) and a nearly adjacent number with EP 0 515 183 A1 — the Briggs & Stratton reference that the specification itself discusses. I am reporting the citation literally as it appears (per the rule not to auto-correct identifiers) and simultaneously flagging that it appears to be an anomalous/erroneous entry in the citation record. I have not silently substituted EP 0 515 183 A1 for it. Assessment: no §102 relevance as listed.

5. Claim-by-claim §102 exposure summary

Bottom line on §102: On the record available to me, no single cited reference discloses every element of claim 1 arranged as claimed, so there is no reference I can responsibly call a full anticipation of independent claim 1. The genuine §102 pressure points are narrow and numeric/structural: claim 4 vs. US 4,615,313, claim 6 vs. US 4,590,905, and claim 7 / claim 1(d)–(e) vs. US 5,150,674 / EP 0 515 183 A1. Everything else in the cited set is §103-type art.

6. Flags and anomalies (stated explicitly, not corrected)

1. EP 0 515 182 A1 vs. EP 0 515 183 A1 (see §4.8). The citation of record is the Samsung "Low-power crystal circuit"; the specification discusses EP 0 515 183 A1, which is the Briggs & Stratton "Improved centrifugally responsive compression release mechanism." Reported literally; not auto-corrected.
2. JPH 09-184410 A timing. Published 1997-07-15, which is after the Hatz priority date (1996-09-11) but before the PCT/US filing (1997-09-04). Because the applicant is entitled to the DE priority date as its invention date, a publication dated 1997-07-15 sits in an awkward window for pre-AIA §102(a) art. Its citation may rest on the examiner treating the filing date as the invention date, or it may be a general state-of-the-art citation. I flag this as a citation-timing question rather than asserting it is improper.
3. "Cited by examiner" star designations are internally inconsistent in the scraped record. The same table renders FR 2,522,725 A1 with a star in one instance and without one in another, while EP 0 167 691 A2, JPH 09-184410 A and US 5,706,769 A are consistently starred. I therefore do not rely on the star flags to attribute citations to the examiner.
4. Intrinsic wording conflict in claim 1 (claim-construction note, not prior art). Claim 1 recites a lifting device operative "at speeds below a switching speed for change over from compression to decompression," whereas the Abstract and description describe the changeover as from decompression to compression at the switching speed. The direction-of-change language in claim 1 is inverted relative to the specification. This matters for claim scope and is worth noting alongside the prior-art analysis.
5. "Similar Documents" ≠ citations of record. US 3,901,199 A, US 4,453,507 A, US 4,790,271 A, US 4,898,133 A, US 4,892,068 A, US 4,671,930 A and US 5,711,264 A appear in the Google Patents "Similar Documents" list, not among the citations of record. Notably, the Briggs & Stratton references US 3,901,199 A (automatic compression relief; U-shaped yoke straddling the camshaft, auxiliary cam, flyweight, camshaft recess, resilient bias) and US 4,453,507 A are, on their face, at least as close to claim 1's "bow-shaped member" wording as several of the face citations. A complete validity/invalidity study should treat them as additional §102/§103 candidates, while making clear they are not cited on the face of US 6,223,708.

7. Limitations on this analysis

• I could not open the full disclosure text of EP 0 167 691 A2, JPS 63-306215 A, US 5,706,769 A, JPH 09-184410 A or US 5,301,643 A in this session; their claim mappings are therefore provisional and should be re-run against the actual documents.
• I could not retrieve the PCT international search report for WO1998011330A1 or the EP 0 925 427 B1 opposition/ examination file, which may cite references beyond the US face list.
• The conclusions above are technical anticipation assessments only. They are not legal opinions, not an invalidity opinion, and not a freedom-to-operate analysis. The patent lapsed for non-payment of maintenance fees effective 2009-05-01 (37 CFR 1.362), so §102 exposure today has historical/validity significance rather than present-enforcement significance.

I'll ground the obviousness analysis in the actual content of the cited references. Let me pull details on the key prior-art documents from the patent's face.

Strong results. Let me pull the remaining cited references to complete the combination picture.

Obviousness Analysis — U.S. Patent 6,223,708 B1 under 35 U.S.C. § 103

Scope note. This section builds on the previously generated bibliographic, claim-summary, and litigation sections and does not repeat them. All patent numbers below are used exactly as they appear on the face of US 6,223,708 or in the search hits for those numbers. Where a hit contradicted the patent page, I flag it (see §8).

1. Legal framework and level of ordinary skill

Standard. A claim is obvious under § 103 if the differences between the claimed subject matter and the prior art are such that the subject matter as a whole would have been obvious to a person having ordinary skill in the art ("POSITA") at the time of the invention, considering (i) the scope and content of the prior art, (ii) the differences, (iii) the level of ordinary skill, and (iv) objective indicia. Graham v. John Deere Co., 383 U.S. 1 (1966). The motivation to combine need not be stated in the references; it may be implicit in the field, in market/design pressures, or in the "predictable results" of combining known elements. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). The useful MPEP 2143 rationales here are: (A) combining prior-art elements according to known methods to yield predictable results; (B) simple substitution of one known element for another; (C) use of a known technique to improve a similar device; (D) applying a known technique to a known device ready for improvement; and (G) "obvious to try."

POSITA. For a mechanical decompression device of the kind at issue, a POSITA would be a mechanical engineer (B.S. or equivalent) with roughly 2–4 years of experience in small internal-combustion-engine valve-train and starting-aid design, or a skilled technician with appreciably more hands-on experience. This is a mature, crowded, empirical field (Briggs & Stratton, Honda, Kawasaki, Fuji, Tecumseh, Hatz), so the POSITA has a robust design vocabulary of flyweights, springs, tappets, rocker/dragging levers, cam recesses, and auxiliary "bump" cams.

Critical admission in the specification. The specification itself identifies European Patent EP 0515183 A1 as the closest centrifugal starting aid and states the motivation for the invention: EP 0515183 A1 suffers from "a rigid connection between flyweight and bow-shaped member," requiring "a relatively large installation space." My search confirms EP 0515183 A1 is the Briggs & Stratton "Improved centrifugally responsive compression release mechanism" — i.e., the EP family member of US 5,150,674 (Gracyalny). This admission is highly probative: it puts the bow-shaped member + flyweight centrifugal decompression architecture squarely in the prior art as of the 1996 priority date, leaving only the manner of coupling and the engagement geometry as the alleged advance.

2. Claim 1 — element-by-element chart against the two strongest references

The single material gap in the primary reference (US 5,150,674 / EP 0515183 A1) is the spring-biased flyweight and the two-piece articulated flyweight — and both are expressly and literally supplied by the Kawasaki reference (US 4,615,313), which is itself cited on the face of the patent. The remaining recitations ("disposed between the cam and a cam disk," "cam-disk plane") are spatial orientations routine in this art and largely present in both references (in US 5,150,674 the cam gear with flyweight apertures is the cam disk, and the release member sits between that gear and the cam).

Conclusion on claim 1: US 5,150,674 (or its admitted EP counterpart EP 0515183 A1) in view of US 4,615,313 renders claim 1 obvious. Neither reference standing alone literally anticipates, but the combination covers every element.

3. Alternative / additional combinations

(a) FR 2,522,725 A1 (Bernard Moteurs) as primary. Discloses a centrifugal decompressor in which a lever and a masselotte (flyweight) are fixed for rotation with the camshaft, the lever carrying a retractable stop (butée escamotable) movable between an active position interposed between the cam and the valve-actuating member and an inactive position; the masselotte moves radially under centrifugal force against an elastic restoring force, guided on a rotary support fixed to the camshaft; the lever translates in an internal axial groove of the camshaft, with an oblique end portion cooperating with a guide element fixed to the masselotte. In view of US 5,150,674 (U-shaped saddle/legs yoke + auxiliary cam on the saddle), claim 1's bow member, pivot geometry and spring-bias are all present. FR 2,522,725 also supplies the sliding-in-a-groove/recess teaching useful against claim 7.

(b) US 4,790,271 A (Honda) as primary. A decompression cam riding loosely on the camshaft adjacent the valve-motion cam, selectively extended beyond the cam base circle during the initial compression stroke, drawn inward by an eccentric weight once a selected rotational speed is reached, and retained by a retaining means; it also teaches a reverse decompression cam for reversed rotation. Combined with US 4,615,313 (spring-biased, jointed twin weight) or FR 2,522,725 (retractable stop between cam and valve actuator), this likewise covers claim 1. US 4,790,271's "reverse decompression cam" is directly relevant to the reversing-start use case the patent touts for its 300–600 rpm switching range.

(c) Accumulated-art combination. A further, cumulative combination — US 5,150,674 + US 4,615,313 + FR 2,522,725 + US 4,790,271 — makes the claimed architecture the sum of individually known, mutually compatible expedients, which is the classic MPEP 2143(A) fact pattern.

4. Motivation to combine (why a POSITA would do it)

1. Same field, same problem, same art. All references are camshaft-mounted, speed-responsive compression-release/decompression devices for internal combustion engines, classified with the patent in F01L 13/08. They are a fortiori analogous art.
2. The specification's own stated object supplies the motivation. The patent's object is "an easy-to-make, low-cost automatic decompression system … [needing] only a small installation space," expressly contrasted with EP 0515183 A1's rigid flyweight-to-bow connection and large space requirement. A POSITA confronting that known problem would naturally look to the two-piece, jointly-pivoted, spring-biased weight arrangement already disclosed in Kawasaki US 4,615,313 (and to FR 2,522,725's guided lever) to decouple the flyweight from the bow. That is a substitution of a known coupling for a known coupling to achieve a predictable result (MPEP 2143(B)), not an inventive leap.
3. Spring bias was a known solution to a known failure mode. Kawasaki expressly uses tension spring 29 so that the weights occupy their rest position "regardless of gravitational forces." Gravity-dependence was the acknowledged weakness of the gravity-biased yoke of US 5,150,674 and its ancestor US 4,453,507 (which itself suggests "the compression release member may be biased to its operative position by a spring or other resilient element"). The Kawasaki combination therefore comes with an articulated reason to combine — the spring-coupling addresses precisely the gravity dependence limitation of the primary reference, enabling the low switching speeds (300–600 rpm) recited in claim 6.
4. Predictable, modular mechanics. Flyweight mass, spring rate, pivot location and auxiliary-cam arc length are independent, well-understood design variables. Nothing in the references teaches away from substituting the coupling; the EP 0515183 "teaching" the patent relies on is at most a disclosure of one known design tradeoff (rigidity vs. compactness), which is a predictable-result optimization, not a teaching away.
5. Market/design pressure. Hand-crank, reversing-cable, and low-power starter use on single-cylinder diesel engines (the patent's own stated application) created a recognized need for reliable low-speed switching and reduced cranking resistance — the "design incentive" recognized in KSR.

5. Dependent claims 2–11

6. Anticipation (§ 102) observations

• Claim 4 is at serious § 102 risk from US 4,615,313 alone: jointed, spring-interconnected twin centrifugal weights 22/25 on pins 20/24 is the literal claim language.
• Claim 1 is best attacked under § 103 rather than § 102, because US 5,150,674's biasing is by weight of the flyweights rather than a spring, and its disengaged neutral position is a camshaft recess rather than the cam-disk plane. US 5,150,674 + US 4,615,313 closes both gaps.
• Claims 6, 9, 11 (numerical ranges) should be attacked under In re Peterson / MPEP 2144.05 (overlapping or adjacent ranges with no criticality), not as anticipation.

7. Anticipated patentee rebuttals and their weaknesses

• Non-analogous art / teaching away. Weak. All references share the field and problem; the EP 0515183 "rigid connection" passage describes a tradeoff, not a discouragement of spring-biased articulated couplings — which Kawasaki and FR 2,522,725 show were the known alternative.
• "Bow-shaped member with a crosspiece" is not the prior-art yoke. Weak on the merits: US 5,150,674 claims a "generally U-shaped" member with "first and second legs connected by a curved saddle" and an "auxiliary cam member attached to the saddle" — structurally the two-arms-plus-crosspiece of claim 1, merely relabeled.
• Secondary considerations. Any assertion of unexpected results, long-felt need, or commercial success would need to be tied to the specific articulated-coupling and cam-disk-plane features, and must overcome the strong § 103 evidence. Long-felt need is weakened by the fact that the same problem was solved in the same way across at least six prior patent families (Briggs, Kawasaki, Honda, Fuji, Bernard Moteurs, Samsung's cited appearance), which cuts toward obviousness rather than away from it.

8. Data-integrity flags (per the "flag contradictions" instruction)

1. Citation-list inconsistency. The Google Patents "Citations (9)" list for US 6,223,708 includes EP 0515182 A1 (Samsung Semiconductor, Inc. — "Low-power crystal circuit"), which is facially unrelated to engine decompression. The specification text, however, discusses EP 0515183 A1 as the closest centrifugal prior art. My independent search confirms EP 0515183 A1 = Briggs & Stratton "Improved centrifugally responsive compression release mechanism" (the EP counterpart of US 5,150,674). I interpret both identifiers literally and do not merge them: EP 0515182 A1 does not appear to be relevant art; EP 0515183 A1 is the reference actually relied upon by the specification and the linchpin of the obviousness case.
2. Claim-language vs. specification inconsistency. Claim 1 recites changeover "from compression to decompression," whereas the abstract and specification describe changeover "from decompression to compression." This does not affect the § 103 analysis (both readings are covered by the cited art) but is a § 112(b) ambiguity worth noting.
3. Cross-reference to earlier sections. The previously generated litigation section flagged search noise from unrelated "6223708-adjacent" patents and a decorative-bow patent whose vocabulary ("bow," "crosspiece," "arms") coincides with US 6,223,708's claims. That warning stands — none of those documents is a § 102/§ 103 reference here.

9. Bottom line and confidence

Claim 1 would have been obvious over US 5,150,674 (Briggs & Stratton; = admitted EP 0515183 A1) in view of US 4,615,313 (Kawasaki Jukogyo), and alternatively over FR 2,522,725 (Bernard Moteurs) in view of US 5,150,674, or US 4,790,271 (Honda) in view of US 4,615,313. Dependent claims 2, 3, 5, 6, 7, 9, 10, 11 would be obvious over these combinations plus routine optimization; claim 4 is independently anticipated (or at minimum plainly obvious) from US 4,615,313; claim 8 is obvious over US 5,706,769 (Honda) combined with any decompression reference. There is no meaningful teaching away.

Confidence:

• High for the § 103 conclusions resting on US 5,150,674, US 4,453,507, US 4,615,313, FR 2,522,725, US 4,790,271 and US 5,706,769 — I retrieved and read substantive text of each (URLs: https://patents.google.com/patent/US5150674; http://data.epo.org/publication-server/rest/v1.2/patents/EP0515183NWA1/document.html; https://patentimages.storage.googleapis.com/aa/c9/12/d5fd3951e54486/US4615313.pdf; https://patents.google.com/patent/FR2522725A1/fr; https://patents.google.com/patent/[US4790271A](/patent/US4790271A)/en; https://patents.google.com/patent/[US5706769A](/patent/US5706769A)/en).
• Low / not verified in this session: the internal content of EP 0 167 691 A2 (Fuji Jukogyo), US 4,590,905 (Honda), JPS 63-306215 A (Honda), JPH 09-184410 A (Honda) and US 5,301,643 (Briggs). I ran out of search budget before retrieving them; I have reasoned about them only from their titles and incorporated them as cumulative, not essential, references. If those documents add nothing, the combinations above stand unchanged; if they add disclosure, the case only strengthens.
• This is an analyst's § 103 assessment of publicly available text, not a legal opinion, and no representation is made about the actual USPTO examination record (file-wrapper estoppel, actual rejections, or appeal outcomes), which I did not retrieve.