US 7194363

I'll search for authoritative information on this patent, including any litigation dockets.

Now let me check for any litigation or CAFC activity involving this patent.

US 7,194,363 B2 — Verification Summary

I searched for this patent number across patent databases and litigation dockets. Note on method: several search hits containing the bare string "7194363" were unrelated identifiers (e.g., tax/registration numbers in Brazilian and Brazilian-archive PDFs, an unrelated "been served" list). Those are excluded as non-patent matches. No CAFC docket or district-court case asserting this patent was located (see Litigation note below).

Bibliographic data (from the patent text and Google Patents / FreePatentsOnline)

Abstract (verbatim)

"A low power ultrasonic flowmeter to be powered by a two wire power supply loop is described, comprising: an ultrasonic flow sensor, a signal processing unit for determining a measurement result based on measurements performed by the ultrasonic flow sensor, an input/output unit to be connected to the two wire loop, for controlling a current of the power supplied to represent the measurement result, for receiving power from the power supply loop, and a power management system, for an energy efficient distribution of the power supplied to the flowmeter via the input/output unit, comprising storage means for storing energy during times of low power consumption and resupplying the stored energy during times of high power consumption."

Independent claims in plain language

Claim 1 — Apparatus (loop-powered ultrasonic flowmeter). A low-power ultrasonic flowmeter designed to run off a two-wire power supply loop, made of:

• an ultrasonic flow sensor;
• a signal processing unit that computes a measurement result from the sensor's measurements;
• an input/output unit connected to the two-wire loop that both (a) controls the loop current so it represents the measurement result and (b) draws its operating power from that same loop; and
• a power management system that efficiently distributes the loop-supplied power, using storage means that bank energy when consumption is low and release it when consumption is high.

The claim's characterizing clause requires the storage means to include both (i) storage for incoming energy received through the input/output unit and (ii) further storage for energy feedback from the ultrasonic flow sensor itself.

Claim 4 — Method (operating the loop-powered flowmeter). A method of operating the low-power ultrasonic flowmeter (preamble recites the flow sensor, signal processing unit, two-wire-loop input/output unit, and a power management system having storage means for incoming energy). A measurement cycle comprises, in order: storing energy during low-consumption periods and re-supplying it during high-consumption periods; initiating at least one ultrasonic signal; receiving the corresponding ultrasonic measurement signal; processing it to produce a measurement result; and outputting according to that result — wherein the power to initiate the ultrasonic signal comes from the power management system using instantaneous incoming power plus power previously stored in the storage means (so the transmit burst is not limited to whatever the loop instantaneously supplies).

Dependent claims: Claim 2 (I/O unit includes send/receive data circuit); Claim 3 (loop complies with an industry standard — Foundation Fieldbus, Profibus, Modbus, HART or Ethernet); Claim 5 (during reception, processing, and output, surplus energy is stored); Claim 6 (energy-consuming components active only when performing; otherwise in low-power standby/inactive mode).

Technical gist of the disclosure

Both illustrated embodiments (Fig. 1 transit-time, Fig. 2 Doppler) rely on the same power architecture: the loop current is the flowmeter's sole power source, 4–20 mA per industry standard. A central unit (19) actively distributes power to sensor electronics, signal processing, I/O, and storage. Two storage elements are described — a first storage means (21) capturing energy feedback from the piezoelectric transducers (harvested while they "ring down" in generator mode before/after transmission and reception), and a second storage means (23) capturing surplus loop energy. The spec also notes power clamping during transmission and the possibility of a multipath (multiple transducer pair) configuration, and says the low power draw permits an intrinsically safe design for hazardous areas.

Uncertainty / caveats

• The abstract and the specification describe a first and a second storage means (feedback vs. incoming), while Claim 1 recites "storage means for storing incoming energy ... and further storage means for storing energy feedback." The mapping of "first/second" to the claim's two elements is a matter of claim construction; I have kept the claim language literal rather than equating them.
• Claim 4's feature of "storing energy ... and resupplying" is placed within the recited measurement-cycle steps, and its preamble references only the incoming-energy storage means (not the feedback means) — I report this as written.
• Authoritative bibliographic data (dates, inventors, assignee, status) came from the patent-as-published and Google Patents/FreePatentsOnline, which agree. I did not independently confirm the current USPTO Patent Center fee/status record beyond what the sources show.

Litigation / CAFC 2026 check

• No 2026 CAFC appeal or district-court case asserting US 7,194,363 was found. No PTAB petition tied to this patent number appeared in the searches.
• For completeness, the only Endress+Hauser patent suit surfaced was Banertek LLC v. Endress + Hauser Inc., No. 2:17-cv-00244 (E.D. Tex., filed 2017-03-30, closed 2017-09-18), which concerned a different patent-in-suit in a networking-sector dispute — it is not a case about US 7,194,363, and I would not attribute it to this patent without confirming the patent numbers in that docket.

Sources: https://patents.google.com/patent/US7194363/en ; https://www.freepatentsonline.com/7194363.html ; https://insight.rpxcorp.com/litigation/txedce-[175076](/patent/175076)-banertek-v-endress-hauser

I'll search litigation databases for this specific patent number.

No relevant hits yet — those results are unrelated. Let me query the litigation-specific databases directly.

Still only identifier collisions. Let me target the assignee and patent-specific litigation portals.

Litigation search — US 7,194,363

Bottom line: No litigation involving US 7,194,363 was located.

I ran targeted searches on the exact identifiers (both 7194363 and 7,194,363) combined with litigation terms, plus assignee-side searches and the patent-litigation trackers I could reach. I found no case — district court, Federal Circuit, ITC, or PTAB — in which US 7,194,363 was asserted, challenged, or otherwise at issue. Accordingly, the requested table has no rows:

What the searches actually returned (and why each was excluded)

Every hit on the bare string 7194363 was an identifier collision, not a patent-litigation match. Consistent with the rule against auto-correcting or conflating identifiers, I excluded all of the following rather than treat them as this patent:

• A 2004 "Been Served" defendant list PDF (Cobb County, GA small-claims-style list) — entry "7194363 Robbert F Henry Tile Co." (archive.org).
• A Brazilian state registration/publication PDF (JUCISRS record) — "7194363 KATIA SIMONE SERPA DO AMARAL."
• New York State DOS entity ID 7194363 (Hfb Consulting / Huntley-Fenner Advisors, Inc.).
• A Czech public-contracts registry version ID 7194363 (Ředitelství silnic a dálnic ČR).
• SNAC archival resource ID 7194363 (a 1554 Westminster document).
• FCC ID document 7194363 (FRC radio cover letter).
• Unrelated PTAB petition exhibits (IDT v. Sony; Uniloc v. Cisco/Avaya; Network System Technologies IPRs) surfaced by keyword overlap — none reference this patent number.
• A Supreme Court docket PDF (Maldonado v. First Service Residential) listing unrelated case citations.

None of these relate to US 7,194,363.

Assignee-side check

• Endress+Hauser Flowtec appears in third-party docket analytics only on the EPO opposition side (e.g., oppositions involving Micro Motion and Diehl Metering), not as a US patent plaintiff asserting this number. The IP Verse competitive-analysis page lists EndressHauser Flowtec's PTAB cases faced as blank/dash (no PTAB cases). Source: https://ipverse.greyb.com/competitive-analysis/company/endresshauser-flowtec
• One lead checked and excluded: Banertek LLC v. Endress + Hauser Inc., No. 2:17-cv-00244 (E.D. Tex., filed 2017-03-30, closed 2017-09-18). As flagged in the earlier-generated verification section, no docket evidence ties that case to US 7,194,363, and it concerned a different patent-in-suit in a networking-sector dispute. I do not report it as litigation involving this patent. I am repeating it only so the lead is visibly closed rather than silently dropped.

Context that bears on the negative result

• The patent is expired. Google Patents shows legal status Expired – Lifetime with anticipated expiration 2023-12-22 (https://patents.google.com/patent/US7194363/en). An expired patent cannot support prospective injunctive relief; only past damages within the 35 U.S.C. § 286 six-year lookback remain theoretically available, and that window recedes daily.
• Single-application family, operating-company owner. Google Family ID 34677996 lists one family application; the owner is Endress + Hauser Flowtec AG, an operating industrial manufacturer — a profile that historically generates few assertion suits.
• The earlier-generated sections reached the same conclusion, so this is consistent, not contradictory: no district-court or CAFC action, and zero AIA trial proceedings (no IPR/PGR/CBM) on this number.

Confidence and limitations (stated explicitly)

• High confidence that no litigation asserting this patent number appears in the indexed public sources I could reach.
• Material limitation: I was unable to query PACER directly, and my site:portal.unifiedpatents.com litigation Endress Hauser Flowtec query returned zero results; the RPX Insight patent-page query was cut off at the tool-step limit before returning data. The negative result therefore rests on general-web and aggregator searches, not on a direct docket-database query.
• I did not fabricate any case number, caption, or outcome to fill the table. There was nothing to report.

Recommended next verification steps

1. PACER / CourtListener RECAP — full-text search "7,194,363" and "7194363" across all district and appellate dockets: https://www.courtlistener.com/?q=%227194363%22
2. Unified Patents litigation case list — https://portal.unifiedpatents.com/litigation/caselist (browse by patent or by party "Endress").
3. PTAB E2E / Patent Search — confirm no post-grant proceeding: https://ptacts.uspto.gov/ptacts/public-informations
4. USPTO Patent Center fee/status history for application 10/740,922, to firm up the 2023-12-22 terminal date (the machine-readable fee record stops at the 2018-09-11 12th-year payment — an open item flagged in earlier sections).

I'll verify the structured PTAB list against live sources before writing up the analysis.

The initial searches surfaced no proceeding tied to this patent. Let me run targeted queries on likely IPR naming conventions and on defensive aggregators.

No PTAB hit yet. Two more checks — one on the PTAB docket aggregators and one for any assertion campaign that might have triggered an IPR.

Proceedings overview

Total AIA trial proceedings on US 7,194,363: zero. The canonical list from the USPTO Open Data Portal ("PTAB proceedings on file") returns no IPR, PGR, or CBM for this patent, and my independent web checks surfaced none — so the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials, and the defensive posture is not "the patent survived two IPRs and is hardened" but something better for a defendant: no PTAB record exists at all, and the patent has expired.

That distinction matters, because the usual inference — "a well-asserted patent eventually attracts IPRs" — does not apply cleanly here. There was no assertion campaign to attract one (see Strategic summary), and the patent's term ran out on 2023-12-22 under Google Patents' recorded anticipated expiration, with legal status shown as Expired – Lifetime.

Proceedings on file

None. There is no proceeding to report at claim-level granularity. To be explicit about what is not being claimed:

• No petition number was found for this patent. I did not locate any IPR/PGR/CBM instituted, denied, or terminated on US 7,194,363.
• No Final Written Decision exists for this patent, so there is no claim-level verdict, no panel quote, and no judge panel to report.
• No Federal Circuit appeal of any such FWD exists.
• AIA-vehicle eligibility, for completeness: a PGR was never available — PGR applies only to patents with an effective filing date on or after 2013-03-16, and this patent's effective filing date is 2003-12-22. A CBM was likewise unavailable on its face (an industrial ultrasonic flowmeter is not a "covered business method" tied to financial products/services), and the CBM program sunset on 2018-09-16. IPR was the only realistic post-grant vehicle — available for the entire life of the patent from 2012-09-16 onward — and no one filed one.

Corroboration and record gaps

• The "PTAB proceedings on file" block (USPTO ODP) is empty for this patent — treated as authoritative.
• Third-party PTAB/litigation trackers index Endress+Hauser Flowtec with zero PTAB cases faced (data coverage from ~2018 forward). This is consistent with, but weaker than, the ODP record. Source: https://ipverse.greyb.com/competitive-analysis/company/endresshauser-flowtec
• Searches for 7194363 / 7,194,363 combined with IPR/petition/litigation terms returned only unrelated identifier collisions (e.g., a "been served" list entry, Brazilian tax/registration PDFs) — the same noise the earlier verification section flagged and excluded. Not relied on.
• One open item worth pulling the full file wrapper for: the Google Patents legal-events table shows maintenance-fee payments only through the 12th-year MAFP entry on 2018-09-11. The next fee (the 15.5-year payment, due on/around 2022-09-20) does not appear in that table. Google nonetheless reports status Expired – Lifetime with anticipated expiration 2023-12-22, which is what you'd expect for a full-term expiry rather than a lapse for non-payment ("Expired – Fee Related" is the usual label for the latter). I could not confirm the fee record directly against USPTO Patent Center, so treat the 2023-12-22 terminal date as the working assumption, subject to a Patent Center / fee-history check — it changes the damages window materially (see below).

Strategic summary

Claim status — the whole claim set is UNTESTED at the PTAB, and all of it is now expired. No claim of US 7,194,363 has ever been canceled or confirmed in an AIA trial. Claims 1 and 4 (the independents) and claims 2, 3, 5, and 6 (dependents) all reached the end of the patent term intact and unadjudicated. There is therefore no IPR-eroded claim set to point to; a defendant cannot say "claims 1–5 are cancelled." The relevant posture is different: the patent right is in the past tense, and any dispute is a past-damages dispute, not an injunction/licensing dispute. Pre-grant publication US 2005/0137812 A1 (published 2005-06-23) is the other tape in the family.

Estoppel — nothing to navigate, and nothing to leverage. With no IPR, § 315(e)(2) estoppel never attached to anyone. Practically:

• A defendant today faces no IPR estoppel and can raise any invalidity ground in district court — § 102, § 103, § 112 — without the § 311(b) prior-art restriction (printed publications/patents only) that binds an IPR petitioner, and without the estoppel shadow that a lost or partially-lost IPR would cast.
• The flip side is that there is no PTAB record (no FWD, no institution decision, no panel findings) to use as ammunition against the claims or as a basis for collateral estoppel. Any invalidity attack on claims 1–6 is a from-scratch district-court or post-grant (ex parte reexamination) project.
• Useful starting points for that project, drawn from the patent's own face: the 11 references cited against it (including US 4,242,665 Two-wire transmitter; US 5,650,571 Low power signal processing and measurement apparatus; US 6,473,710 Low power two-wire self validating temperature transmitter (Rosemount); US 6,640,308 System and method of powering and communicating field ethernet device… using a single pair (Invensys); US 6,845,330 Electromagnetic flowmeter (Yamatake); US 2004/0107779 A1 Ultrasonic current meter), plus U.S. Pat. No. 5,207,101, which the specification itself describes as a prior two-wire ultrasonic level measurement device with the amplifier disabled in a sleep mode — i.e., the patent admits the loop-powered-ultrasonic-measurement architecture and the power-down concept as known. Whether 5,207,101 or any cited reference discloses the claim-1 characterizing feature (feedback-energy storage plus incoming-energy storage) is an open question I am not resolving here.

Pattern signals — there is no pattern. No repeat petitioner (there is no petitioner). No patent-owner PTAB appeal activity (there is nothing to appeal). No defensive aggregator in the chain: no Unified Patents or RPX-style filing on this number appeared in any search, and none would be expected for an industrial flowmeter patent of this vintage and this narrow market. The only Endress+Hauser patent suit surfaced anywhere in this analysis is Banertek LLC v. Endress + Hauser Inc., No. 2:17-cv-00244 (E.D. Tex., filed 2017-03-30, closed 2017-09-18), which the earlier verification section correctly declined to attribute to this patent — I likewise do not attribute it here, and no docket evidence ties it to US 7,194,363.

Recommended next steps

1. If you have received a demand letter citing US 7,194,363, lead with expiration, not PTAB. There is no FWD to quote — I will not manufacture one. What is quotable is the patent's own record: Google Patents shows status Expired – Lifetime and anticipated expiration 2023-12-22 (https://patents.google.com/patent/US7194363/en). Confirm the terminal date and the fee history at USPTO Patent Center / Patent Maintenance Fees before responding, because the maintenance-fee record in the machine-readable legal events stops at the 2018-09-11 12th-year payment. If the 15.5-year fee was not paid, the patent lapsed earlier (fall 2022) and the recoverable window shrinks accordingly. This is the single highest-value verification step.

2. Map the damages window before you map the merits. Under 35 U.S.C. § 286, a complaint filed today (2026-09-28) reaches back only to 2020-09-28 — which is a ~3.2-year sliver of the patent's life, ending at terminal expiration 2023-12-22. Accused conduct after 2023-12-22 is not infringement of an expired patent. Note also that the § 286 six-year bar is a rolling limit: every day that passes between now and the filing of a complaint shrinks the reach-back into the patent's enforceable term, and once the complaint is filed after roughly 2029-12-22, the six-year window no longer overlaps the patent term at all.

3. Do not assume the patent owner is powerless just because there is no PTAB history. The absence of IPRs is a weak signal here, not a strong one: this appears to be a single-application US family (Google Family ID 34677996 lists one family application), owned by a large operating company (Endress+Hauser Flowtec AG) rather than a monetization entity — a profile that historically generates few IPRs regardless of merit. The more meaningful characteristics for a defendant are (a) whether the patent ever asserted, and (b) whether anyone else's product practices claims 1–6.

4. If you want an AIA-style validity adjudication, IPR is gone and reexamination is the remaining route. An IPR petition can technically be filed against an expired patent, but with no ongoing infringement exposure the economics are poor and any claim-amendment path is foreclosed by expiration. Ex parte reexamination (35 U.S.C. § 302 et seq.) remains available to anyone, at any time, based on patents and printed publications — it is the only PTAB-adjacent validity vehicle left for this number. District-court invalidity remains fully open (see Estoppel, above).

5. Standing searches to run before you rely on "no PTAB activity." The ODP ingestion is the authoritative source but may lag new filings. Confirm at PTAB E2E / PTAB Patent Search (https://ptacts.uspto.gov/ptacts/public-informations) and cross-check CourtListener for both PTAB appeals (https://www.courtlistener.com/?q=%227194363%22) and any district-court docket naming the patent. Neither search produced a hit for this number in my checks.

Constraints honored: no proceeding numbers, panels, grounds, institution decisions, or FWD dispositions have been invented; there were none to report. Every claim-level statement above is a statement about the absence of adjudication, and the only disposition-adjacent facts asserted are bibliographic (expiration date, status, claim set) drawn from the patent text and Google Patents / FreePatentsOnline, which agree. The maintenance-fee gap is flagged as unresolved rather than asserted as a conclusion.

I'll research the assignment record for this patent.

Let me search for the specific assignment reel/frame and any subsequent transfers.

Inventors

Pattern check: No unusual inventor pattern. Both inventors assigned to the corporate assignee by a single instrument executed 2004-07-21 — about 7 months after the 2003-12-22 filing, which is the normal course for a corporate obligation-to-assign executed at issue-prep time, not a distress signal. There is no evidence of inventors departing, no individual-to-individual reassignment, and no separate inventor-owned continuation. (Contrast with the "fire-sale precursor" pattern, which requires a strip of inventors selling out within 12 months of filing — not present here.)

Original assignee

Endress + Hauser Flowtec AG (a.k.a. Endress+Hauser Flowtec AG), Kägenstrasse 7, 4153 Reinach, Switzerland. Recorded as assignee from the 2004-07-21 assignment (reel 015461/0909), and the assignee of record on the face of the issued patent. This is the flow-measurement division and a core operating subsidiary of the privately held, family-controlled Endress+Hauser Group (Swiss; founded 1953, Reinach).

• Primary line of business: industrial process instrumentation — electromagnetic, Coriolis, vortex, thermal and ultrasonic flowmeters, plus the associated transmitters (Proline family; the ultrasonic line is Prosonic Flow).
• Did they ship a product embodying the claims? Highly likely — the claims are directed to a two-wire loop-powered ultrasonic flowmeter, which is exactly the commercial category E+H Flowtec sells. Caveat: I did not do a claim-by-claim product teardown; the product-embodiment statement is based on the assignee's product line, not on verified infringement/coverage analysis.
• Current status: Operating. No bankruptcy, no Chapter 7/11, no acquisition of the assignee, no change of name recorded. Because E+H is a privately held Swiss group and not a US-listed issuer, there are no SEC 10-K/8-K filings to cross-check (an expected negative, not a gap in the search).
• Ownership continuity: Endress+Hauser Flowtec AG remained assignee through grant and through the patent's full life. The patent expired (anticipated) 2023-12-22 on the 20-year term; status is "Expired – Lifetime."

Assignment timeline

I could not load the Assignment Center record page directly (the USPTO assignment interface did not return a citable record page in the searches I ran). The reel/frame below is taken from the free-format assignment text and the legal-events table reproduced on the Google Patents record for US 7,194,363 B2, both of which agree on the reel/frame and the free-format conveyance description. The correspondent of record is therefore unverified — I am not going to invent an attorney name.

2004-07-21 (executed) / recorded 2004-12-14 — Reel 015461/0909

• Conveyance: Assignment — "ASSIGNMENT OF ASSIGNORS' INTEREST (SEE DOCUMENT FOR DETAILS)" (Google Patents legal-event code AS)
• Assignor: Dean Sylvia; Joe Schaffer (the two named inventors, in their individual capacities)
• Assignee: Endress + Hauser Flowtec AG, Kägenstrasse 7, 4153 Reinach, Switzerland
• Correspondent: Not retrievable from the sources I could access. The record's correspondent/attorney of record is not exposed in the Google Patents legal-events rendering, and my searches did not surface the reel 015461/0909 recordation notice. I am flagging this as an open item rather than substituting a guess. (Method note: the correspondent field is the single most useful tell for anonymous LLC chains, so it matters — here, however, there is no LLC chain to trace.)
• Context: Initial inventor → employer assignment at prosecution stage. Not an acquisition, fire-sale, securitization, or transfer-to-asserter. This is the only recorded conveyance for this patent.

No further assignments exist. Every post-issuance entry in the record is a grant or fee event, not a title transfer:

• 2007-02-28 — STCF (patent grant / patent case)
• 2009-12-06 — FEPP (fee-payment procedure; payor number assigned)
• 2010-09-15 — FPAY, 4th-year maintenance fee
• 2014-09-11 — FPAY, 8th-year maintenance fee
• 2018-09-11 — MAFP, 12th-year maintenance fee (paid; entity status large entity)

There is no security agreement, no merger, no change-of-name record, no license recordation, and no release. Maintenance fees were paid at all three statutory windows (4th/8th/12th year), so the patent was not abandoned for non-payment — consistent with "Expired – Lifetime" at the 2023-12-22 term end.

Cross-references checked:

• Litigation: No district-court or CAFC action asserting US 7,194,363 was found (consistent with the prior section). No pre-litigation transfer window exists to analyze.
• PTAB: No IPR/PGR petition naming this patent appeared.
• RPX / Unified Patents asserter directories: Neither Endress+Hauser Flowtec AG nor any successor appears as a high-frequency plaintiff or NPE.
• SEC: Not applicable — assignee is not a US reporting company.

*(Minor discrepancy note, per cross-reference instruction: the previously generated summary listed the assignment's recorded date and effective date but not the reel/frame. This section supplies reel 015461/0909. No contradiction — the dates match.)*

Timeline diagram

timeline
    title Ownership of US 7194363
    2003 : Application filed by two inventors
    2004 : Assignment recorded to Endress + Hauser Flowtec AG
    2007 : Patent issued as US 7194363 B2
    2018 : Third maintenance fee paid
    2023 : Patent expires on 20 year term

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT.
There is exactly one recorded conveyance (reel 015461/0909), and it runs from two individual inventors to an operating industrial manufacturer, not from an operating company to a licensing-only LLC. No assignee with an "IP / Patents / Licensing / Holdings / Ventures" suffix appears anywhere in the chain. No registered-agent-service address; the assignee's recorded address is the group's real Reinach, Switzerland headquarters (Kägenstrasse 7).

2. Known asserter in the chain — NOT PRESENT.
The only parties in the chain are Dean Sylvia / Joe Schaffer and Endress + Hauser Flowtec AG. Neither matches Acacia, Marathon Patent Group, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or any Spangenberg entity. No Unified Patents / RPX high-frequency-plaintiff match.

3. Repeat correspondent across the chain — UNCLEAR / NOT ASSESSABLE.
This signal is defined by recurrence across multiple links, and there is only one link, so there is nothing to recur across. Separately, I was not able to retrieve the correspondent of record for reel 015461/0909 from the accessible sources. I am recording this as an unverified field rather than inferring a name. Even if a correspondent were identified, a single appearance is not a finding under the stated rule.

4. Cascading transfers — NOT PRESENT.
No chained LLCs. One assignment, executed 2004-07-21, recorded 2004-12-14 — a 7-month execution-to-record lag, well within normal corporate practice, and there is no second transfer within any 24-month window to chain to.

5. Pre-litigation transfer — NOT PRESENT.
There is no infringement suit naming this patent (confirmed for 2026, and none found earlier), so there is no assignment-timed-to-suit event and no venue/standing-arrangement indicia. The sole assignment predates grant by ~3 years, which is the opposite of a pre-suit transfer.

6. Bankruptcy fire-sale — NOT PRESENT.
No Chapter 7/11, receivership, or asset sale involving the assignee. Endress+Hauser Group remains a privately held, family-controlled operating group (no Kodak/Nortel/Polaroid-style event). Maintenance fees were paid at 4, 8, and 12 years, which further evidences a solvent owner actively maintaining the asset.

7. Privateering — NOT PRESENT.
No transfer to any NPE, and no NPE assertion on the operating company's behalf. The patent never left the operating group.

8. Defensive aggregator (anti-NPE) — NOT PRESENT.
The chain terminates at the original operating-company assignee, not at RPX, AST, LOT Network, Unified Patents, or OIN. There was no need for the patent to be "neutralized" because it was never asserted; it simply expired with its original owner.

Verdict

Insufficient data — in the specific sense the option is defined (only the original assignment exists).

Justification: the sole recorded conveyance is reel 015461/0909 (executed 2004-07-21, recorded 2004-12-14), an inventors→employer assignment of the entire interest to Endress + Hauser Flowtec AG, and it is the only title record for this patent. All later entries are grant and maintenance-fee events (4th year 2010-09-15; 8th year 2014-09-11; 12th year 2018-09-11) culminating in expiry on 2023-12-22 — so there is no post-issuance ownership chain to score for NPE behavior, and zero of the eight NPE signals are affirmatively present. The affirmative findings are all negative ones: no asserter in the chain, no shell LLC, no cascading transfers, no suit, and the patent died with its original operating-company owner. One field remains open — the correspondent of record for reel 015461/0909 could not be retrieved — and I am flagging that as an unverified item rather than treating it as a signal.

Verify at: https://assignmentcenter.uspto.gov/ (search application 10/740,922 or patent 7,194,363; alternative index https://assignment.uspto.gov/patent/index.html) — reel 015461/0909 is the entry to inspect for the correspondent/attorney of record.

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

Prior-Art Analysis — US 7,194,363 B2 ("Ultrasonic flowmeter")

0. Scope, method, and a note on the search

• Target confirmed. The identifier 7194363 resolves only to US 7,194,363 B2, application US 10/740,922, filed/priority 2003‑12‑22, granted 2007‑03‑20, inventors Joe Schaffer & Dean Sylvia, assignee Endress + Hauser Flowtec AG. The search returned no look‑alike numbers (e.g., 7194636, 7194336) mapped to this record. Google Patents and FreePatentsOnline agree, as recorded in the earlier bibliographic section.
• Database caveat (honesty note): the searches I ran resolved to Google Patents / Justia / FreePatentsOnline / uspto.report pages, which mirror USPTO data, rather than a direct USPTO Patent Center/PatFT query (I could not click through to a live USPTO page in this session). I also hit the tool‑call limit before I could retrieve full text for all eleven front‑page citations; where I rely on title/abstract rather than the full specification, I flag it as [abstract/title only].
• Governing law: because the application was filed 2003‑12‑22 (before 2013‑03‑16), pre‑AIA 35 U.S.C. § 102 applies. This matters for the references published after the 2003 filing date — those are only available as prior art as of their U.S. filing dates under pre‑AIA § 102(e).
• The 11 examiner‑cited references are the starting point below. I also treat the specification's own background reference, US 5,207,101 ("two‑wire ultrasonic level measurement device"), separately in §3 because it is arguably more on‑point than several front‑page citations.

1. Claim‑element shorthand (for mapping)

Claim 1 = A + B + C + D + E + F.
Claim 4 = method preamble (A, B, C, D, E) + cycle steps (initiation → reception → processing → output) + "power for initiation … utilizing instantaneous incoming power and power stored in the storage means."

2. The examiner‑cited references, one by one

2.1 US 4,242,665 — "Two‑wire transmitter"

• Full citation: US 4,242,665 A; Action Instruments Company, Inc.; filed 1978‑09‑15; issued 1980‑12‑30.
• Description: A loop‑powered two‑wire transmitter that draws power from the loop wires and stores a portion of that power during spaced‑apart first intervals, then discharges it in short bursts to excite an external sensor during second intervals (retrieved text states ~40 ms store / ~2.5 ms discharge, a ~10:1 instantaneous‑power step‑up because continuous draw "would be prohibitive"); the sensor response is sampled/held and a variable resistance sets loop current representative of it. (The sensor is a resistance bridge, not ultrasonic.)
• § 102 mapping: This is the closest cited art to element D + E and to claim 4's "instantaneous incoming power + stored power" burst concept. However it lacks A (ultrasonic) and F (feedback storage from the ultrasonic sensor).
• Potentially anticipates: None of the claims as a whole. It cannot meet claim 1 or claim 4 (missing A and F). It is best treated as § 103 art (single‑reference obviousness candidate for the general loop‑energy‑storage/burst feature). Status: § 102(b) bar (published >1 yr before 2003‑12‑22).

2.2 US 5,650,571 — "Low power signal processing and measurement apparatus"

• Full citation: US 5,650,571 A; inventor Paul J. Freud; filed 1995‑03‑13; issued 1997‑07‑22.
• Description: Transit‑time ultrasonic flow measurement with two transducers, each functioning as transmitter and receiver; analog correlation (bucket‑brigade/CCD/SAW) instead of power‑hungry digital correlation; a delay counter to defer activation of correlation/ADC/processor to conserve energy; expressly framed for a 4–20 mA two‑wire loop / battery / low‑power field bus, for intrinsically safe field use (claim 15 recites the 4–20 mA two‑wire loop).
• § 102 mapping: Supplies A and much of the claim‑4 cycle (initiation → reception → processing → output) and the low‑power two‑wire context. Lacks D/E/F (no power‑management storage means, no incoming‑energy reservoir, no transducer feedback storage).
• Potentially anticipates: None as a whole; strongest § 103 partner for the ultrasonic/low‑power framing. Status: § 102(b).

2.3 US 6,473,710 B1 — "Low power two‑wire self validating temperature transmitter"

• Full citation: US 6,473,710 B1; Rosemount Inc.; app. 09/606,259 filed 2000‑06‑29, priority 1999‑07‑01; issued 2002‑10‑29.
• Description: Two‑wire temperature transmitter in which a power supply is configured to completely power the transmitter from the two‑wire process control loop; ADC + microprocessor + two‑wire loop communicator; dual temperature elements for self‑validation.
• § 102 mapping: Bears on C (loop‑powered I/O) and the "loop is the sole power source" idea; also a § 103 candidate for claim 3 (loop‑standard communicator, e.g., HART) [abstract/title only for the standard].
• Potentially anticipates: None as a whole — no ultrasonic sensor, no storage means, no feedback harvesting. Status: § 102(b) (issued >1 yr before filing).

2.4 US 6,452,493 B1 — "Process control instrument with multiple functions"

• Full citation: US 6,452,493 B1; SOR, Inc.; filed 2000‑01‑19; issued 2002‑09‑17.
• Description: Combined switch/gauge/transmitter powered by a single two‑wire loop, controller controls loop current 4–20 mA to represent the sensed variable; sensor may be pressure/temperature/volumetric flow/level.
• § 102 mapping: Bears on C and claim‑3‑style loop standard; mentions flow as an option.
• Potentially anticipates: None as a whole. Status: § 102(b).

2.5 US 6,640,308 B1 — "System and method of powering and communicating field ethernet device … single pair of powered ethernet wire"

• Full citation: US 6,640,308 B1; Invensys Systems, Inc.; filed 1999‑04‑16; issued 2003‑10‑28.
• Description: Powering and communicating a field device over a single twisted pair (powered Ethernet / "field Ethernet"). [abstract/title only]
• § 102 mapping: Relevant only to claim 3 (two‑wire loop complying with an industry standard, notably Ethernet). Nothing on ultrasonic sensing or energy storage.
• Potentially anticipates: None as a whole; at most supports a § 103/§ 102 challenge to the dependent claim‑3 enumeration. Because it issued 2003‑10‑28 (inside one year of the 2003‑12‑22 filing), prior art is via § 102(e) as of its 1999‑04‑16 filing date.

2.6 US 6,928,866 B2 — "Device for the measurement and monitoring of a process parameter"

• Full citation: US 6,928,866 B2; Endress + Hauser GmbH + Co. KG; filed 2001‑02‑05; issued 2005‑08‑16.
• Description: [abstract/title only] A process‑parameter measurement/monitoring device from the same corporate family as the assignee.
• § 102 mapping: General field‑instrument context; no teaching retrieved bearing on E/F (dual storage) or ultrasonic feedback harvesting.
• Potentially anticipates: None as a whole. Issued after the target's filing (2005‑08‑16), so prior art is only § 102(e) as of 2001‑02‑05; note the common‑ownership / same‑family issue (§ 103(c); the "Endress + Hauser GmbH" vs. "Endress + Hauser Flowtec AG" entity distinction should be checked before relying on it).

2.7 US 2004/0107779 A1 — "Ultrasonic current meter"

• Full citation: US 2004/0107779 A1; inventor Masao Kishimoto; filed 2001‑05‑16; published 2004‑06‑10.
• Description: [abstract/title only] Ultrasonic meter for measuring current/flow velocity.
• § 102 mapping: Bears on A (ultrasonic sensing of flow) only.
• Potentially anticipates: None as a whole. Pre‑AIA § 102(e) prior art as of 2001‑05‑16.

2.8 US 2003/0045962 A1 — "Control system using process model"

• Full citation: US 2003/0045962 A1; inventor Evren Eryurek; filed 2001‑08‑30; published 2003‑03‑06.
• Description: [abstract/title only] Process control using a process model — control‑loop/consumer‑side context.
• § 102 mapping: Peripheral to B/claim 4 output ("measurement data used to control complex industrial processes"). Nothing on the flowmeter power architecture.
• Potentially anticipates: None as a whole. § 102(e) as of 2001‑08‑30.

2.9 US 2003/0126932 A1 — "Mass flowmeter and method for operating a mass flowmeter"

• Full citation: US 2003/0126932 A1; inventor Helmut Brockhaus; filed 2001‑12‑06; published 2003‑07‑10.
• Description: [abstract/title only] Mass flowmeter and its operating method (Brockhaus is an Endress+Hauser‑associated name).
• § 102 mapping: Method‑of‑operation framing only; no dual‑storage power management.
• Potentially anticipates: None as a whole. § 102(e) as of 2001‑12‑06.

2.10 US 6,845,330 B2 — "Electromagnetic flowmeter"

• Full citation: US 6,845,330 B2; Yamatake Corporation; filed 2002‑04‑18; issued 2005‑01‑18.
• Description: [abstract/title only] Electromagnetic flowmeter (loop‑powered flow‑instrument context).
• § 102 mapping: Flow‑instrument environment; non‑ultrasonic sensing; no storage means.
• Potentially anticipates: None as a whole. Issued after filing → § 102(e) as of 2002‑04‑18.

2.11 US 2004/0120109 A1 — "Front‑accessible communications port for enclosed electrical equipment"

• Full citation: US 2004/0120109 A1; inventor Robert A. Kennedy; filed 2002‑10‑07; published 2004‑06‑24.
• Description: [abstract/title only] A communications‑port/housing arrangement for field equipment.
• § 102 mapping: At most peripheral to claim 2 (I/O unit having a send/receive data circuit) — and even then, tangential.
• Potentially anticipates: None as a whole. § 102(e) as of 2002‑10‑07.

3. The specification's own background reference (not on the front page)

US 5,207,101 — "Two‑wire ultrasonic level measurement device." Cited in the Background as the closest known two‑wire ultrasonic instrument; it uses a single transducer, disables/awakens its amplifier circuit in a sleep mode to save power, and controls loop current to represent the measurement. This is the reference the specification uses to distinguish its invention ("Ultrasonic flowmeters usually comprise two ultrasonic transducers. Accordingly, power consumption of ultrasonic flowmeters is generally higher…"). It is highly relevant to C and to the low‑power/sleep aspect of dependent claim 6, but it is a level device, not a flowmeter, and discloses no D/E/F. [I did not retrieve full text for US 5,207,101 in this session; inventor/assignee not verified — treat the attribution as unconfirmed.]

4. Cross‑cutting § 102 conclusion

No single one of the eleven cited references appears to anticipate any claim of US 7,194,363 as a whole. The claims' distinctive combination is the dual‑storage power‑management system: (i) storage of incoming loop energy (element E) and (ii) further storage of energy fed back from the ultrasonic flow sensor itself — i.e., harvesting the piezoelectric transducer's ring‑down/generator‑mode energy (element F) — plus the burst‑transmit use of "instantaneous incoming power and stored power" (claim 4).

Accordingly:

• Closest § 102‑type signal references, by sub‑feature: US 4,242,665 (store‑loop‑energy‑then‑burst‑excite; claim‑1 elements D/E and claim‑4's stored‑power‑for‑initiation) and US 5,650,571 (low‑power ultrasonic transit‑time cycle on a two‑wire loop; claim‑4 steps).
• No anticipation of claims 1–6 as a whole. The cited art is properly characterized as § 103 background, and the practical novelty/validity fulcrum is element F (harvesting transducer ring‑down energy) combined with E, which the cited references do not teach.
• Dependent claims: claim 2 (data send/receive circuit) and claim 3 (loop standard — Foundation Fieldbus/Profibus/Modbus/HART/Ethernet) are the most exposed to § 102/§ 103 attack, because each adds a well‑known, separately documented feature (loop communicators: US 6,473,710; powered‑single‑pair Ethernet: US 6,640,308). Claim 5 (surplus‑energy storage during receive/process/output) and claim 6 (standby/inactive components) also map to known low‑power techniques (e.g., the sleep mode of US 5,207,101; the delay counter of US 5,650,571).

5. Explicit uncertainties

• Full specifications were retrieved for US 4,242,665, US 5,650,571, US 6,473,710, US 6,452,493, and (partially) US 6,640,308. For the remaining six, my descriptions rest on title/abstract only and are flagged.
• I did not locate an examiner's citation category (e.g., X/Y/A) for these references (the front‑page list carries no relevance codes), so the § 102 vs. § 103 characterization above is my analysis, not an official examiner designation.
• Common‑ownership (§ 103(c)) and same‑family issues (US 6,928,866 B2 and US 2003/0126932 A1 involve Endress+Hauser‑linked names) should be verified before relying on those two as art.
• No contradiction with the earlier-generated summary was found; the bibliographic data here is consistent with it.

Sources used: https://patents.google.com/patent/US7194363/en ; https://www.freepatentsonline.com/7194363.html ; https://patents.justia.com/patent/[4242665](/patent/4242665) ; https://patents.google.com/patent/US5650571 ; https://patentimages.storage.googleapis.com/15/e8/ee/121502b0c6984e/US6473710.pdf ; https://patents.google.com/patent/[US6452493B1](/patent/US6452493B1)/en ; https://insight.rpxcorp.com/patent/[US6473710B1](/patent/US6473710B1)

I'll ground this analysis in the actual prior-art references listed on the patent page. Let me pull details on the key citations.

Good grounding on the key low-power loop-powered references. Let me pull the remaining cited references.

Obviousness Analysis — US 7,194,363 B2 under 35 U.S.C. § 103

Scope note. This analysis is built from the prior-art references listed on the patent page itself: the 11 "Patent Citations" (applicant/examiner-cited), the applicant-admitted prior art in the specification, and the related documents in the page's "Similar Documents" section. All references identified below published (or were filed, for pre-AIA § 102(e) purposes) before the 2003-12-22 effective filing/priority date. The '363 patent is pre-AIA, so pre-AIA § 103(a) governs. Where I rely on art not in the page's citation list, I flag it explicitly and mark my confidence.

1. Legal framework and the PHOSITA

Controlling standard. Pre-AIA § 103(a); Graham v. John Deere, 383 U.S. 1 (1966); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). Under KSR, a combination is obvious where the elements are known, the combination is of familiar elements according to known methods, and it yields no more than predictable results; an express teaching, suggestion, or motivation to combine is not required — the "inventive" step can arise from "ordinary creativity," market demand, design incentives, and the "finite number of identified, predictable solutions."

PHOSITA (as of Dec. 2003). A designer of industrial process instrumentation with a B.S. in electrical engineering and 2–4 years' experience in loop-powered (two-wire, 4–20 mA) field transmitters, familiar with HART/Fieldbus signaling, ultrasonic transducers, and low-power circuit design for hazardous-area (intrinsically safe) operation.

Claim construction point (relevant to both validity and infringement). The "storage means for storing…" recitations in claims 1 and 4 are means-plus-function limitations under § 112 ¶ 6; the specification discloses them as capacitors/energy-storage elements (spec: "storage means 21, 23"; "an energy storing element… especially a capacitor" appears in the closely-related E+H art). This does not change the § 103 analysis but means the claim covers any structure performing the recited storing function.

2. The applicant's own admissions (which shorten the obviousness inquiry)

The '363 specification admits a large part of the claim 1 architecture as prior art:

• "instrument manufacturers developed devices known as two-wire or loop powered measurement devices… comprises only two connectors… The measurement result is transmitted via the same two wires, which are also used for supplying power to the device."
• "An industry standard has been developed according to which the measurement devices are powered by a 24 volt DC power source and the loop current varies between four and twenty milliamps representing the measurement result."
• "In U.S. Pat. No. 5,207,101 a two-wire ultrasonic level measurement device is described comprising [inter alia] an input/output unit to be connected to a two wire loop, for controlling a current of the power supplied to represent the measurement result and for receiving power from the power supply loop… In order to minimize power consumption, the level measurement device is configured to normally operate in a sleep mode by disabling an amplifier circuit… when it is not necessary for operation and by awakening it when it is necessary."
• The spec also concedes the one structural distinction the inventor asserts over level meters: "Ultrasonic flowmeters usually comprise two ultrasonic transducers. Accordingly, power consumption of ultrasonic flowmeters is generally higher than power consumption of ultrasonic level measurement devices."

These are applicant admissions (In re Fout; Constant v. Advanced Micro-Devices) that the loop-powered, 4–20 mA, current-representing-the-result, sleep-mode architecture is old and well known, and that the only recognized problem to be solved was supplying enough instantaneous power to fire a higher-consumption, two-transducer flow sensor.

3. Element-by-element mapping of claim 1

Reading of the claim. Every element of claim 1 except the last row is squarely in the prior art. The only genuinely distinguishing limitation is the second buffer that captures "energy feedback from the ultrasonic flow sensor" — i.e., harvesting the piezoelectric transducer's mechanical ring-down (generator-mode) energy rather than dissipating it. That is where any § 103 defense must concentrate, and it is also the limitation the examiner apparently treated as the point of novelty.

4. Combination 1 (primary): US 5,650,571 + US 5,207,101 + US 6,473,710

The combination. Freud '571 supplies the loop-powered low-power ultrasonic flowmeter itself (transit-time, upstream/downstream, two transducers, correlator/ADC/processor, intrinsically safe, 4–20 mA two-wire). Haynes '101 supplies the two-wire ultrasonic transmitter conventions: loop current representing the measurement, 4–20 mA signaling, power-gating of the drive/amplifier circuits so they are energized only for the minimum necessary window, and express recognition that at 4 mA "there is minimal power available… circuits must be designed to operate off of such minimal available power." Rosemount '710 supplies the express teaching that a two-wire process instrument's power supply may be "solely" loop-derived.

Why a PHOSITA would combine them.

1. Same field, same problem, same solution space. All three are loop-powered process instruments addressing the identical constraint (worst-case 4 mA current = minimum available power). KSR holds this "finite number of identified, predictable solutions" setting makes the combination obvious.
2. Freud '571 itself frames the problem the '363 patent claims to solve. Its stated object is "to provide a measurement apparatus which avoids the high power digital signal processing means while retaining the accuracy" for "a two wire 4-20 ma transmitter system." A PHOSITA seeking to make a loop-powered ultrasonic flowmeter work would begin exactly here.
3. Remote-location/cabling economics. Both '101 and the '363 specification recite the same motivation verbatim in substance (cost of cabling for four-wire devices). This is the classic KSR-recognized market pressure.
4. Intrinsic safety. Both '101 and '571 expressly recite hazardous-area/intrinsically-safe design as the reason for limiting energy storage and consumption — the same benefit the '363 spec claims. Motivation to combine is thus express, not merely inferable.
5. HART/data-over-loop (relevant to claim 2) was already standard in loop-powered level/flow transmitters (US 2003/0045962 A1, Eryurek; US 6,640,308, Invensys).

Result. Claims 1, 2, 3, 5 and 6 would be prima facie obvious over '571 + '101 + '710, with the caveat in §6 regarding the "energy feedback" element of claim 1.

5. Method claims 4–6

Claim 4 recites the measurement cycle (initiate → receive → process → output) and the single functional requirement that "power for initiation of ultrasonic signal is provided by the power management system utilizing instantaneous incoming power and power stored in the storage means."

This is the strongest obviousness case in the patent, because it is disclosed almost verbatim in the art:

• US 5,434,178, cl. 5/7/8/10: an ultrasonic transducer coupled to a two-wire 4–20 mA loop with "means for storing power received from the two wire communication loop and providing stored power to the means for periodically exciting," wherein the exciting means is "a switch coupled between the means for storing power and the ultrasonic transducing element." That is precisely "instantaneous incoming power plus stored power used to fire the transmit burst."
• US 5,650,571 supplies the remainder of the cycle for a flow meter (transmit, receive, correlate, ADC, processor, output) and the energy-conserving delay-counter sequencing.
• US 5,207,101 supplies the alternating drive/enable sequence in a two-wire ultrasonic instrument.

Motivation: both '571 and '101 identify the 4 mA worst case as the design driver; buffering energy so a high-current transmit burst is not limited by instantaneous loop current is the ordinary, predictable engineering response ("obvious to try" in KSR terms).

Claim 5 (surplus energy stored during receive/process/output): routine charge-management during the low-consumption phase; disclosed in substance by US 5,434,178 (cl. 5) and by the general reservoir-capacitor scheme. Obvious.

Claim 6 (components active only when performing; low-power standby otherwise): directly disclosed by US 5,207,101 — "each said drive circuit and receive circuit normally being disabled by said control circuit," and "energizing the amplifier circuit for a select minimum time duration." Reinforced by US 5,650,571 (delay counter to conserve energy) and by US 6,014,100 A ("Two-wire RADAR sensor with intermittently operating circuitry components"), which appears on the patent page's own "Similar Documents" list. Claim 6 is plainly obvious and borders on anticipated.

6. The one real battleground: "energy feedback from the ultrasonic flow sensor"

I want to be candid here rather than assert a conclusion the record does not support.

The case for obviousness. (a) Piezoelectric transducers were notoriously known to keep ringing after excitation and to act as generators when mechanically driven — the '363 spec merely states this as known behavior ("the electro-mechanical transformer… does not immediately stop swinging… operating in a generator mode"). (b) US 5,207,101 already couples a "ring down attenuator circuit" to the transducer, demonstrating that the artisan recognized and deliberately managed this residual energy. Converting a dissipation circuit into a recovery circuit with a rectifier and a storage capacitor is the kind of substitution of known elements with predictable results that KSR condemns. (c) The motivation is express in the art: '101 and '571 both stress that every microwatt matters at 4 mA. (d) Energy harvesting from piezoelectric elements into a capacitor was a well-known technique by 2003.

The case against obviousness (the applicant's best argument). No reference in the page's citation list expressly discloses storing the transducer's own mechanical feedback energy and re-supplying it to the power management system for the next operation. US 5,207,101's ring-down attenuator teaches the opposite disposition (damp/dissipate). A patentee could therefore argue that the combination of two independent buffers — one for loop energy, one for sensor feedback — was not suggested, and that a new source of energy (mechanical, from the transducer) was tapped, yielding a benefit that is not merely the sum of the parts. That is a legitimate, non-frivolous nonobviousness position, and I would not dismiss it.

My assessment. This limitation is more likely than not obvious to a PHOSITA, but it is the only limitation that supports a serious § 103 defense. A validity challenge that does not squarely address it (e.g., that relies only on US 5,207,101 or US 6,473,710 alone) will fail.

7. Supplementary art (not in the page's citation list) — flagged

US 5,434,178 is the most material reference I found for claims 4 and 5 (loop-power storage feeding the ultrasonic exciter; ultrasonic transducer coupled to a two-wire 4–20 mA loop). It appeared in this session's search results as a Magnetrol-style "time gate ultrasonic sensor." Caveat: I retrieved only its claim text and could not verify its bibliographic data (assignee, issue date, family) within this session. Its claim language and structure place it in the mid-1990s US patent-number range, i.e., comfortably pre-2003, but treat the citation as provisional pending verification. (US 5,207,101 itself is cited in the "Similar Documents" history and is applicant-admitted in the '363 spec, so its status is firm.)

US 6,014,100 A (two-wire radar with intermittently operating components) — on the page's "Similar Documents" list; strong art against claim 6.

Applicability dates for the two 2004-published citations. US 2004/0107779 A1 (Kishimoto) and US 2004/0120109 A1 (Kennedy) are only available as prior art under pre-AIA § 102(e) as of their US filing dates (2001-05-16 and 2002-10-07), not their 2004 publication dates. They cannot be combined for their 2004 disclosure content in a pre-AIA § 103 rejection except as to subject matter present in the earlier-filed application.

Later art (not available). US 7,058,521 B2 (Panametrics, "Low power ultrasonic flow meter," filed 2004-03-26) and DE 10 2011 114 246 B4 (Diehl) appear in the page's "Families Citing this family" list — they post-date the '363 priority date and are not prior art. They are, however, evidence of the field's later development and would be relevant to damages/§ 101 discussions, not § 103.

8. Secondary considerations / objective indicia

I found no evidence of unexpected results, long-felt-but-unresolved need, failure of others, industry praise, or commercial success attributable to the claimed combination. The specification's asserted benefits (energy efficiency, intrinsic safety, hazardous-area use) are each independently recited as existing benefits of the prior art in US 5,207,101 and US 5,650,571, so they cannot serve as nexus-bearing evidence of nonobviousness. Without a demonstrated nexus to the feedback-energy buffer specifically, these considerations do not rebut the prima facie case.

9. Bottom line

Primary combination to plead: US 5,650,571 (Freud) as the primary reference for the low-power two-wire ultrasonic flowmeter, in view of US 5,207,101 (Haynes/Magnetrol) for the two-wire ultrasonic transmitter conventions, current-representing-output, power-gated drive/amplifier circuits, and ring-down management, and further in view of US 6,473,710 (Rosemount) for sole-loop power supply; with US 5,434,178 for the stored-power-to-exciter limitation of claims 4–5 and US 6,014,100 for claim 6. The motivation is supplied by (i) the express shared object of operating a two-wire 4–20 mA instrument at the 4 mA worst case, (ii) the cabling-cost and intrinsic-safety pressures recited in both the references and the '363 specification itself, and (iii) KSR's "predictable solutions" rationale.

Residual uncertainty. (1) The "energy feedback from the ultrasonic flow sensor" limitation is the one element for which I did not locate express disclosure in the listed art; my conclusion that it is obvious rests on the known generator-mode behavior of piezoelectric transducers plus '101's ring-down attenuator, which is an inference, not a citation. (2) My US 5,434,178 citation is provisional pending bibliographic verification. (3) I could not retrieve the text of US 2003/0126932 A1 (Brockhaus) or US 2003/0045962 A1 (Eryurek) in this session, so any use of them should be verified before filing.

Sources: https://patents.google.com/patent/US7194363/en ; https://patents.google.com/patent/US5207101A/en ; https://patents.google.com/patent/US5650571 ; https://patents.google.com/patent/US6473710 ; https://patents.google.com/patent/[US6452493B1](/patent/US6452493B1)/en ; https://patents.google.com/patent/[US6845330B2](/patent/US6845330B2) ; https://patentimages.storage.googleapis.com/67/0a/f2/6f3cad3cad96e5/[US5437178](/patent/US5437178).pdf ; https://patents.google.com/patent/[US6014100A](/patent/US6014100A) ; https://patents.google.com/patent/[US6640308B1](/patent/US6640308B1)