US 11371757

I'll search for the specific patent number and any related litigation activity.

Let me run a few more targeted searches on USPTO records and litigation.

Let me do two final checks for litigation/IPR activity and USPTO record confirmation.

US Patent 11,371,757 — Summary

Bottom line on the searches: I could not confirm any CAFC 2026 docket, district-court litigation, or PTAB proceeding involving US 11,371,757 using available search tools. Searches for "11371757" combined with litigation/PTAB/Federal Circuit terms returned only unrelated hits (e.g., a Feit IPR dispute, and a coincidental SEC EDGAR accession number belonging to Matrixx Initiatives — not this patent). Treat "no litigation found" as an absence of evidence, not proof of absence; a direct PACER/Docket Navigator or CAFC docket query would be needed to be conclusive. My summary below is grounded in the patent's own full text (Google Patents, fetched 2026‑09‑24) plus corroborating public records.

Bibliographic data (per the patent record)

One inconsistency worth flagging: a PatentGuru listing for this family shows "IP Business Solutions, LLC" alongside the E.T.L. entry. I could not determine from the search results what role that entity plays (it appears in a formatting context that may be an agent/representative field rather than an assignee). The recorded assignment data and Google Patents both point to E.T.L. Corporation as owner.

Abstract (as issued)

The system is provided with (a) a cooling-purpose heat exchange section that, during cooling, subcools refrigerant discharged from the compressor and liquefied by the heat source side heat exchanger, using an "acceleration phenomenon" produced by rotating the refrigerant helically before it reaches the pressure reducing device/expansion valve, and (b) a heating-purpose heat exchange section that, during heating, partially vaporizes refrigerant discharged from the compressor and liquefied by the use side heat exchanger, using the same helical-rotation acceleration, after the expansion valve and before the heat source side heat exchanger. In the heating-purpose heat exchange section, a heating-purpose coiled narrow tube has a flow passage formed wider than that of the cooling-purpose coiled narrow tube of the cooling-purpose heat exchange section.

Plain-language overview of the independent claim (claim 1)

Claim 1 is the only independent claim; claims 2–6 depend from it.

Claim 1 covers a reversible (heat-pump) heating/cooling system with:

1. A heat source side unit containing a compressor and a four-way valve, plus a heat source side heat exchanger, and a use side unit with a use side heat exchanger.
2. An expansion valve for decompressing refrigerant.
3. A cooling-purpose heat exchange section that, when the four-way valve is in the cooling position, subcools refrigerant that left the compressor and was liquefied in the heat source side heat exchanger — by putting a helical (spinning) rotation on the refrigerant, described as an "acceleration phenomenon," before the refrigerant reaches the expansion valve.
4. A heating-purpose heat exchange section that, when the four-way valve is in the heating position, partially vaporizes refrigerant that left the compressor and was liquefied in the use side heat exchanger — by the same helical-rotation acceleration — after the expansion valve and before the heat source side heat exchanger.
5. The two heat exchange sections connected in parallel in the pipeline between the heat source side heat exchanger and the expansion valve.
6. A first on-off valve between the heat source side heat exchanger and the cooling-purpose heat exchange section, open during cooling and closed during heating.
7. A second on-off valve between the heat source side heat exchanger and the heating-purpose heat exchange section, closed during cooling and open during heating.
8. The key structural limitation: the heating-purpose coiled narrow tube's flow passage is wider than that of the cooling-purpose coiled narrow tube.

In plain terms: two parallel helical-coil "turbulence/acceleration" devices sit in the liquid line, one used in cooling and one in heating, each switched in by its own on-off valve — and the heating-side narrow coil is deliberately made bigger than the cooling-side one so that during heating the refrigerant is not over-throttled and stays hot enough entering the outdoor (heat source side) exchanger, which the patent says raises compressor suction temperature and thereby heating efficiency.

Dependent claims (plain language)

• Claim 2 — The cooling-purpose section additionally includes a cooling-purpose coiled wide tube upstream of the cooling-purpose coiled narrow tube, which subcools the refrigerant via the same helical-rotation acceleration. (In the spec, coil 51 upstream of coil 52.)
• Claim 3 — The heating-purpose section additionally includes a heating-purpose coiled wide tube downstream of the heating-purpose coiled narrow tube, which partially vaporizes the refrigerant via the same helical-rotation acceleration. (Spec coil 62 downstream of coil 61.)
• Claim 4 — Flow-rate ratios: the cooling-purpose heat exchange section's flow rate is ≥ 2× that of the heat source side heat exchanger, and the heating-purpose heat exchange section's flow rate is ≥ 2× that of the use side heat exchanger.
• Claim 5 — Each heat exchange section is made by winding a pipeline into a coil, with inner diameter set according to the compressor's discharge capacity.
• Claim 6 — A heat exchange unit that integrally houses both the cooling-purpose and heating-purpose heat exchange sections (the retrofit module of FIG. 2, reference sign 70, connected by piping 71/72).

Notable points and stated advantages

• The specification reports ~16% energy savings versus conventional technique during cooling, and claims improved heating efficiency because the wider heating-side narrow tube suppresses temperature drop, so refrigerant enters the heat source side heat exchanger relatively warm and is drawn into the compressor warm.
• Example dimensions in the spec: cooling-purpose coiled narrow tube inner diameter 8–12 mm; heating-purpose coiled narrow tube 15–33 mm (with a note that the cooling coil is the reference diameter); coiled wide tubes acceptable 2–150 mm, desirable 2–50 mm; downstream coil should be ≥50% of the upstream coil's inner diameter to avoid excessive throttling.
• The sole prior-art citation of record is JP 2013-122363 A (assigned to E・T・E株式会社 / ETE), which the patent characterizes as improving efficiency only during cooling. Other citations of record include JPS6073073U, JPH08200890A, KR0156386B1, JP2000213822A, KR20040086294A, WO2007034939A1, US2008/0245098A1, WO2010082483A1, US2015/0204552A1, and WO2019/155644A1 (a sibling E.T.L. family filing).
• Two caveats for downstream analysis: (1) the claimed subject matter uses "expansion valve" and expressly recites the parallel connection and the two on-off valve placements, which are described in the specification mainly through FIG. 1 (valves 53, 63) rather than expanded upon in the written description; and (2) the specification's operative mechanism — that subcooling/partial vaporization results from enthalpy being converted to velocity energy in a coil, causing a "static temperature drop" under a so-called "acceleration phenomenon of the refrigerant" — is the patent's own asserted theory. I am not offering an independent technical endorsement of that thermodynamic explanation, only reporting how the document frames it.

Uncertainty statement: I have high confidence in the bibliographic and claim content above because it comes from the full patent text. I have low-to-no confidence about current litigation/PTAB/Federal Circuit activity, because my searches surfaced nothing for this number and the tools returned unrelated docket material; any litigation status should be verified directly against PACER, Docket Navigator, or the CAFC docket.

I'll search litigation databases and related sources for US patent 11371757.

Initial searches didn't surface relevant hits. Let me try more targeted queries on litigation databases.

Let me check dedicated patent litigation databases and docket sources.

Litigation Search Results for US Patent 11,371,757

Bottom line: I found no litigation — district court, ITC, or PTAB — involving US Patent 11,371,757. Based on the searches I was able to run, there is no known patent litigation asserting or challenging this patent.

What the patent is, for identification

To confirm I was tracking the correct patent (and not a similar number), I verified its identity from the authoritative full text:

• US 11,371,757 B2, "Heating and cooling system"
• Application No. US 16/978,975; PCT/JP2018/010671; priority/filing date 2018-03-13; granted 2022-06-28
• Assignee: E.T.L. Corporation (ETL Corp), Japan
• Inventors: Naoki Sugiyama, Mitsuto Hisashige, Fumiharu Kurita, Tomoko Okamoto
• 6 claims (claim 1 directed to a four-way-valve heat pump with parallel cooling- and heating-purpose heat exchange sections and a heating-purpose coiled narrow tube whose flow passage is wider than the cooling-purpose coiled narrow tube)
• Family: EP3767201B1, JP6458918B1, KR102374746B1, CN111819404B, WO2019176122A1

Searches run and what they returned

Important caveats on confidence

• This is a negative result, not a certified all-clear. I was not able to directly query the paywalled/portal litigation databases (RPX Insight, Docket Alarm, Unified Patents portal, PACER) in a way that let me run a definitive docket search on this number; those tools generally require interactive access. My conclusion rests on open-web searches.
• US 11,371,757 issued in June 2022 and its family members (EP, JP, KR, CN) are all active, with maintenance fees paid (4th-year fee paid 2025-10-20) — so the patent is in force and could be asserted, but no assertion appeared in my searches.
• No CAFC appeal or PTAB (IPR/PGR) proceeding referencing this patent was found.
• I did not find results for any similar numbers and have not substituted them; the "11371757" hits returned were the patent itself.

Recommendation

If you need a legally reliable answer (e.g., for a clearance or FTO opinion), the negative result should be confirmed by a direct docket search on:

• PACER / CourtListener RECAP for "11,371,757" and for assignee "E.T.L. Corporation"
• Docket Alarm / RPX Insight litigation records for the patent number
• USPTO PTAB (IPR/PGR/CBM) and USPTO PatentCenter / Assignment records
• ITC EDIS Section 337 investigations naming E.T.L. Corporation

If you'd like, I can attempt further targeted searches (e.g., on specific HVAC manufacturers who might be licensees or defendants, or on E.T.L. Corporation's related patents) if you can provide access to one of the portal databases.

Proceedings overview

Total AIA trial proceedings on US 11,371,757: zero (0). Breakdown by status: 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, 0 institution denials. The USPTO Open Data Portal (ODP) AIA-trial dataset returns no IPR, PGR, or CBM proceeding naming this patent, and targeted open-web searches (PTAB petitions/decisions, PTAB E2E-style databases reproduced in search results, litigation-tracking portals, CourtListener/CAFC) surfaced no proceeding, no notice of filing date accorded, and no Federal Circuit appeal.

Bottom line for a defendant: The patent has not been tested at the Board at all. There is no IPR estoppel of any kind in existence, no cancelled claim, and no FWD or institution decision to leverage or to fear. A defendant's posture is the opposite of "hardened by prior IPRs and out of runway" — it is completely untested. Your entire § 102/§ 103 case is still on the table, and the first-to-file IPR option is open (subject to the § 315(b) one-year bar if and when you are served with a complaint).

No proceedings to list

There is no {PROCEEDING_NUMBER} to enumerate. I am not going to populate the per-proceeding template with invented numbers; the structured "PTAB proceedings on file" block is empty, and I found nothing on the web to supplement it.

Searches run (all negative for this patent):

⚠️ Explicit near-number false positive — do not conflate. Web results repeatedly return U.S. Patent No. 11,369,757 ("the '369,757 patent"), which is a different patent owner and technology: PAX Labs Inc.'s oil-vaporizing-device patents, asserted at the ITC in Certain Oil Vaporizing Devices, Components Thereof, and Products Containing the Same, Inv. No. 337-TA-1392 (instituted 2024-03-06; see the March 2025 final initial determination discussing U.S. Pat. Nos. 11,369,756; 11,369,757; 11,766,527; 11,759,580 and STIIIZY Inc. v. ITC, Fed. Cir. appeal briefing). That is a different patent with a transposed digit pair, and it is not US 11,371,757. Any docket search you run on this family must key on 11,371,757 exactly; a substring search for "1137…757" will pull the PAX/STIIIZY matter and produce a false litigation signal.

Strategic summary

Claim status: all six claims (1–6) are UNTESTED. No claim of US 11,371,757 has been cancelled, narrowed by certificate, construed by the Board, or adjudicated unpatentable in any AIA proceeding. Claim 1 — the sole independent claim, reciting the four-way valve, the expansion valve, parallel cooling-purpose and heating-purpose heat exchange sections between the heat-source heat exchanger and the expansion valve, the first and second on-off valves, and the heating-purpose coiled narrow tube flow passage formed wider than that of the cooling-purpose coiled narrow tube — stands exactly as granted 2022-06-28. Claims 4 (flow rate ≥ 2× the associated heat exchangers), 5 (coiled pipeline inner diameter set according to compressor discharge capacity), and 6 (heat exchange unit integrally accommodating both sections) are likewise untouched and have never been construed.

Estoppel landscape: none exists. Because there has been no instituted proceeding and no FWD, 35 U.S.C. § 315(e)(1) (Board estoppel) and § 315(e)(2) (civil-action/ITC estoppel) have attached to nobody. There is no petitioner, real party in interest, or privy carrying estopped grounds. Practically: a defendant can raise every § 102/§ 103 ground on every claim, in the district court and in a future IPR, with no residual-estoppel trap. Correspondingly, a defendant who files the first IPR takes on that estoppel risk itself — worth weighing before pulling the trigger.

Pattern signals: no pattern, because there is no activity. No serial petitioner, no repeat challenger, no Unified Patents or other defensive aggregator in the chain, and no aggressive PTAB-appeal posture by E.T.L. Corporation — because there has been nothing to appeal. The only "related-file" signal worth noting is a sibling application, not a challenge: WO2019155644A1 ("Cooling/heating system," E.T.L., priority 2018-02-09) is a family-adjacent E.T.L. filing, and KR20230071189A is a later E.T.L. family member ("refrigeration unit," 2023-05-23). Neither is a PTAB proceeding against this patent.

Caveat on confidence. Zero is what the canonical ODP data says and what my searches corroborate, but a negative web result on a relatively low-profile Japanese-origin HVAC patent is not the same as a certified PACER/PTAB-E2E all-clear. PTAB E2E and PatentCenter both support a party-name search ("E.T.L. Corporation") that would catch a proceeding even if the patent number were transcribed inconsistently. I was not able to execute an interactive docket query directly, so treat this as "no evidence of any proceeding," not "affirmatively proven none."

Recommended next steps

Because there is no PTAB activity, the honest answer is the absence itself — and that absence is a signal. A patent that issues in 2022, is asserted commercially, and has an aggressive-competitor footprint in HVAC would normally attract at least a Fintiv-style IPR petition by now. The fact that none exists suggests either (a) E.T.L. Corporation has not asserted the patent in a way that has triggered a challenge, or (b) the likely defendants have not yet had the § 315(b) clock start. Either way, for a defendant receiving a demand letter today:

1. Confirm the negative directly, on the record. Run the patent number and the owner name through PTAB E2E (https://ptab.uspto.gov) and USPTO Patent Center / Assignment for U.S. Pat. No. 11,371,757 and App. No. 16/978,975, and search CourtListener RECAP (https://www.courtlistener.com/?q=%2211%2C371%2C757%22) for any district-court or ITC assertion. Run the ITC EDIS search for "E.T.L. Corporation" to rule out a Section 337 investigation — note the PAX/STIIIZY § 337-TA-1392 investigation is a different patent and must not be mistaken for this one.
2. Treat claim 1's "wider flow passage" limitation as the central battleground. It is the only limitation that distinguishes this patent from the admitted prior art (Japanese Patent Laid-Open 2013-122363, cited on the face of the patent) and is defined in the specification only in soft, numerical terms — cooling-purpose coiled narrow tube inner diameter "desirably 8 to 12 mm," heating-purpose coiled narrow tube "15 to 33 mm" when the cooling tube is 8–12 mm. That is a ripe § 112(a)/§ 112(b) written-description and indefiniteness target, and a ripe obviousness target if the prior art shows a wider heating-side restrictor. Grounds of that type have historically performed well at institution.
3. Watch the § 315(b) clock. No litigation has been found, so no one is time-barred. The first defendant served with a complaint has one year from service to file; parties not served have no bar at all. If you are a defendant deciding whether to file, note that filing now makes you the estoppel-bearing petitioner under § 315(e)(2), while a patent owner that has not asserted the patent anywhere cannot easily argue Fintiv factors against you.
4. Do not cite an FWD, an institution decision, or a Board claim construction here — none exists. Any argument to a court or the Board should say plainly that the patent has never been before the PTAB and that claims 1–6 are untested. That is accurate, and it is also the most useful fact in this file for a defendant.

Links for verification of the (empty) record:

• PTAB E2E / AIA trial search: https://ptab.uspto.gov/patent/ipr
• USPTO Patent Center for App. 16/978,975: https://patentcenter.uspto.gov/
• CourtListener RECAP search: https://www.courtlistener.com/
• Patent text: https://patents.google.com/patent/US11371757/en
• Do not cite the PAX/STIIIZY ITC matter or STIIIZY Inc. v. ITC as authority about this patent — it concerns U.S. Pat. No. 11,369,757, a different patent.

I'll research the assignment chain, the assignee's corporate history, and any NPE/asserter signals.

Let me dig into the assignee's corporate identity, the attorney/correspondent of record, and related family assignments.

Let me pin down the correct E.T.L. Corporation (the Japanese HVAC patentee), its founder, and any assignment/litigation footprint.

Assignment & Ownership Analysis — US 11,371,757 B2 ("Heating and cooling system")

Method / source limitation (read first): I could not open the USPTO Assignment Center record interactively; the reel/frame, assignor list, conveyance type and dates below are taken from the legal-events mirror of the USPTO assignment data on the patent's Google Patents record (fetched 2026‑09‑24), which reproduces the Assignment Center entry verbatim (reel/frame, signing dates, assignee, "ASSIGNMENT OF ASSIGNORS INTEREST"). The correspondent field is not exposed in that mirror; the attorney/agent attribution below is drawn from a third-party agent column and is flagged as an inference, not a confirmed recording-correspondent field. Any FTO-grade conclusion should be re-verified at assignmentcenter.uspto.gov and assignment.uspto.gov.

Inventors

Pattern notes:

• This is not a "all inventors departed within 12 months" fact pattern. The inventor group is a small, stable cluster: Sugiyama, Hisashige and Okamoto reappear together on E.T.L.'s 2020 "Freezing apparatus" filings (KR20230071189A, DE112020007780T5, WO2022107343A1), i.e. they were still contributing to the portfolio ~2.5 years after this patent's 2018 filing. That is a signal of a continuing in-house R&D team, not a fire-sale precursor.
• One structural oddity worth recording: inventor Okamoto is the principal of an affiliated company (E・T・E) that is also the assignee of the patent's sole cited prior art (JP 2013‑122363 A, "Refrigerating device," E・T・E株式会社). So the same individual straddles the applicant side and the background-art side. I read this as a related-entity/intra-group situation, not evidence of an NPE chain — but it does mean the "prior art" cited against this patent originates in the same inventor circle.
• The technology's originator appears to be Takao Hara (原 隆雄), whose "velocity-heat converter / acceleration phenomenon" patents (e.g. JP 6357598 B1, "冷暖房システム," held by 合同会社原隆雄研究所) and PCT filings predate this family. Hara is not a named inventor here, and his rights were assigned to ETL Corporation under a separate, earlier record (Reel 037431/0515, effective 2015‑11‑05) relating to a different patent — not this one.

Original assignee

• Entity on the issued patent: E.T.L. Corporation (株式会社Ｅ・Ｔ・Ｌ) — Google Patents shows "E T L Corp" / original assignee "ETL Corp"; assignment record names "E.T.L CORPORATION, JAPAN" (Reel 053714/0127). JP 5537573 B2 lists the company's registered address as 1‑1‑7 Moto-Akasaka, Minato-ku, Tokyo.
• Primary line of business: development, design, manufacture, sale and installation of energy-saving equipment for refrigeration and air-conditioning — specifically spiral-tube ("velocity-heat converter") coils retrofitted into the liquid line of compressors/outdoor units.
• Product embodying the technology: the "Miracle Coil" (ミラクルコイル) — a copper spiral tube / swirl-and-rectifier described in a 2015 trade profile of the affiliated E・T・E(株) as retrofittable to existing air conditioners, refrigerators and freezers, claimed to cut power consumption 10–25% and peak demand ≥25%. Caveat: the Miracle Coil is a single spiral device; the patent claims a reversible system with parallel cooling- and heating-side sections plus two on-off valves and a wider heating-side narrow tube. The Miracle Coil is therefore a partial embodiment of the claimed system, not a verified full-claims practice. I could not locate product literature for a two-section, four‑way‑valve commercial unit.
• Current status: operating, small/micro entity, no evidence of acquisition, dissolution or bankruptcy. Corroborating facts: (a) the patent owner is recorded as a micro entity and paid the 4th-year maintenance fee on 2025‑10‑20 — consistent with a small independent company still holding the asset; (b) the company was still filing (2020 "Freezing apparatus" family) after this patent's grant; (c) every family member (EP 3767201 B1, JP 6458918 B1, KR 102374746 B1, CN 111819404 B) is active.
• Disambiguation note (important): search results also surface an unrelated "E T L Corporation" at Fuchu City, Tokyo (president 李庚模; garbage disposers, electroplating chemicals, insulation paint). That entity is not this patentee and I have excluded it. Likewise, E.T.L. Corporation is distinct from E・T・E株式会社 (the affiliated, but separate, operating company) and from 合同会社原隆雄研究所 (Hara's godo kaisha).

Assignment timeline

One recorded assignment exists for US 11,371,757. There is no post-issuance assignment of record.

• 2020‑07‑13 → 2020‑07‑16 (executed — signing dates span four days) / recorded 2020‑09‑08 — Reel 053714 / Frame 0127
  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNORS INTEREST")
  • Assignor(s): Naoki Sugiyama; Mitsuto Hisashige; Fumiharu Kurita; Tomoko Okamoto (all four named inventors)
  • Assignee: E.T.L. Corporation (Japan) — recorded assignee name "E.T.L CORPORATION, JAPAN"
  • Correspondent: not exposed in the source I could access. The U.S. prosecuting agent of record for this application is IP Business Solutions, LLC, 2311 Wilson Blvd, 3rd Floor, Arlington, VA 22201 (Japanese-language contact: Akiyoshi Onda / 恩田 晃好, a.onda@ipbiz-solutions.com; site: ipbizsolutions.com), per the agent column on PatentGuru's US 11,371,757 listing. I am inferring this firm filed the 2020‑09‑08 recording; treat as unconfirmed. Repeat-player assessment: IP Business Solutions is an ordinary U.S. prosecution boutique serving Japanese clients (patentbots shows ~69 issued patents across 10 clients in the year ending 2026Q1 — Kyocera Document Solutions, DMG Mori, Faurecia Clarion, Tomy, etc.). It is not an NPE assertion firm, and it appears once in this chain. One appearance is not a finding.
  • Context: Initial employment/inventor-to-applicant assignment — the standard pre-grant capture of inventor rights by the PCT applicant for the §371 national stage. It is not a post-issuance transfer, securitization, or transfer-to-asserter. Notably, it was executed ~7 months after the 2018‑03‑13 PCT filing and ~23 months before the 2022‑06‑28 grant.

No further records. Nothing has been recorded against this patent since grant. Under the Assignment Center's own logic, that means E.T.L. Corporation remains the owner of record today.

Timeline diagram

timeline
    title Ownership of US 11371757
    2018 : PCT application filed by E.T.L. Corporation
    2020 : Inventors assign rights to E.T.L. Corporation
         : Reel 053714 frame 0127
    2021 : US pre-grant publication
    2022 : Patent issued to E.T.L. Corporation
    2025 : 4th year maintenance fee paid

NPE / troll-pattern signals

Aggregate read: zero NPE signals present; the profile is the inverse of the classic monetization chain — a sole, pre‑issuance inventor assignment to a small operating manufacturer that has retained the asset, paid maintenance fees as a micro entity, and kept filing in the same space.

Verdict

Verdict: Insufficient data (only the original assignment) — but affirmatively not an NPE pattern on the available record.

Justification: the USPTO record contains exactly one conveyance, executed 2020‑07‑13 to 2020‑07‑16 and recorded 2020‑09‑08 at Reel 053714/Frame 0127, by which inventors Sugiyama, Hisashige, Kurita and Okamoto assigned their rights to E.T.L. Corporation — the original applicant and current owner of record, with no post-issuance transfers, no chained LLCs, no known asserter, and no defensive aggregator at the end of the chain. Because that single entry is an inventor-to-applicant employment assignment and nothing has been recorded since grant, the case falls squarely within the "only the original assignment" prong of Insufficient data; it cannot be scored as "operating-company assertion" (no suit was found — see the litigation section) or as "defensive/non-asserting" (the chain does not end at RPX/AST/LOT/Unified). Substantively, every affirmative indicator (operating business, commercial spiral-coil product, micro-entity fee payments, continued filings) points to a small Japanese operating patentee rather than a troll.

Verify at: USPTO Assignment Center — search US 11,371,757 · Assignment Search (legacy index)

Residual uncertainties I want to flag rather than paper over: (1) I could not read the Assignment Center's correspondent field directly, so the IP Business Solutions attribution is an inference from the prosecuting-agent record; (2) the "Miracle Coil" product I identified is a partial embodiment, and I have no verification that a commercial unit practices all of claim 1; and (3) I found no SEC or bankruptcy filings for this owner, which is expected for a private Japanese micro-entity but means the "no fire-sale" call rests on absence of evidence plus the positive indicators above.

I'll verify the cited references and pull details on each before assessing §102 relevance.

Now let me pull details on the remaining cited references.

Scope note before the analysis

Two disclosures up front, so you can weight what follows correctly:

1. Source of record. I worked from the authoritative full text of US 11,371,757 B2 ("Heating and cooling system," App. No. 16/978,975, PCT/JP2018/010671, filed and priority 2018‑03‑13, granted 2022‑06‑28, assignee E.T.L. Corporation), including its complete "Citations (11)," "Patent Citations (18)," and "Family Cites Families (8)" tables. I did not auto-correct any number; every identifier below is reproduced literally from that record.
2. Search completeness. I hit a tool-step cap partway through verification. I was able to open WO 2007/034939 A1 (full text, claims, family), WO 2019/155644 A1 (abstract/summary), and WO 2010/082483 A1 (title/date) directly. For JPS6073073U, JPH08200890A, KR0156386B1, JP2000213822A, KR20040086294A, US 2008/0245098 A1, US 2015/0204552 A1, and JP 2013‑122363 A I have only the metadata and titles carried in the patent's own citation tables — I did not read those documents. Where that matters I say so explicitly rather than inferring content.

Because the '757 application was filed after 2013‑03‑16, the AIA version of 35 U.S.C. § 102 governs throughout.

1. The § 102 landscape in one paragraph

The prior art of record divides cleanly into three groups:

• Group A — the "acceleration phenomenon" lineage (Hara / Hara Tech / E.T.L.): WO 2007/034939 A1, its US/EP/JP siblings, WO 2010/082483 A1, and its siblings. These supply the helical-coil + "acceleration phenomenon" concept that is the heart of the '757 disclosure.
• Group B — the two-coil refrigerating device of Patent Literature 1: JP 2013‑122363 A (E・T・E株式会社), the only reference the '757 specification itself discusses as prior art.
• Group C — a sibling/co-pending E.T.L. filing: WO 2019/155644 A1 (株式会社Ｅ・Ｔ・Ｌ, priority 2018‑02‑09), which discloses an almost identical cooling/heating coil architecture and is the single most dangerous reference on the list.

Bottom line: on the record as it stands, no single reference appears to disclose every limitation of claim 1, so there is no clean § 102 anticipation of the independent claim. The real exposure is (a) WO 2019/155644 A1 as § 102(a)(2) art (subject to the common-ownership exception of § 102(b)(2)(C)), and (b) JP 2013‑122363 A + WO 2007/034939 A1 as a § 103 combination against the cooling-side dependent claims.

2. Complete citation table (as recorded on the '757 face)

★ = flagged in the record as cited by the examiner; the remainder appear as other citations of record (the listing's third-party attribution is not fully determinable from the table itself).

Separately, the "Family Cites Families (8)" list (citations appearing in other family members' search reports, not on the '757 face) adds: JP2002340447A, JP2003279197A (Central Engineering Kk), KR100812777B1 (Daewoo — "Cooling/Heating Separation Heat Pump"), CN100580345C and CN102252466B (Midea — "Secondary throttling and recooling device of air conditioner" / "Secondary throttle pipe-in-pipe recooling device"), JP5485602B2 (株式会社Ｅ・Ｔ・Ｌ — "Refrigeration system"), JP2012193919A (Takao Hara — "Velocity-heat converter and heating/cooling system utilizing the same"), and KR101856239B1 (an LCD-panel patent — apparent noise).

3. Tier 1 — references with genuine § 102 potential, analyzed individually

3.1 WO 2019/155644 A1 — the most relevant reference on the record

• Full citation: WO 2019/155644 A1, "Cooling/heating system" (冷暖房システム), PCT/JP2018/006096, applicant 株式会社Ｅ・Ｔ・Ｌ (E.T.L. Corporation), inventor 原 隆雄 (Takao Hara). Priority/filing 2018‑02‑09; published 2019‑08‑15.
• Disclosure (per the published abstract): a cooling-purpose heat conversion section comprising a cooling-purpose coiled wide tube and a cooling-purpose coiled narrow tube, and a heating-purpose heat conversion section comprising a heating-purpose coiled narrow tube and a heating-purpose coiled wide tube, wherein the heating-purpose coiled narrow tube has a flow passage formed wider than that of the cooling-purpose coiled narrow tube. The stated object — efficient operation in both cooling and heating using coiled narrow and wide tubes — is the same object recited in '757.
• § 102 analysis — this is the crux:
  • § 102(a)(1): Not available. Its publication date (2019‑08‑15) postdates the '757 effective filing date (2018‑03‑13).
  • § 102(a)(2): Potentially available. Under 35 U.S.C. § 374, an international application designating the United States is deemed published under § 122(b). WO '5644 names a different inventor (Hara) and was effectively filed 2018‑02‑09, before 2018‑03‑13. It therefore qualifies as prima facie § 102(a)(2) art if its US national-phase entry was effected.
  • § 102(b)(2)(C) exception: This is where the reference likely dies. The exception removes as prior art subject matter that, "not later than the effective filing date," was owned by the same person or subject to an obligation of assignment to the same person. Both WO '5644 and '757 trace to the E.T.L. corporate family. If common ownership at 2018‑03‑13 is establishable, WO '5644 is excepted from § 102(a)(2) and becomes non-art. That is the single most important factual question in any validity analysis of '757.
• Potential anticipation mapping: If it were treated as prior art and if it discloses the full circuit, it would reach claims 1, 2, 3, and likely 4 and 5. I flag a caveat: the published abstract I retrieved recites the coil architecture but does not mention the four-way valve, the parallel connection of the two sections between the heat source side heat exchanger and the expansion valve, or the two on-off valves. Those are precisely the limitations that distinguish granted claim 1 from the '757 specification's own summary of the invention (the pre-grant claim language used "pressure reducing device" without the on-off-valve recitations). A reviewer should read the WO '5644 full text and drawings to confirm whether the on-off valves and parallel branch appear there.

3.2 WO 2007/034939 A1 — the origin of the "acceleration phenomenon"

• Full citation: WO 2007/034939 A1 (and family: EP 1930669 A1 / B1, JP 4411349 B2, US 2009/0241591 A1, CN 101273239 A/B), "Thermal converter for condensation and refrigeration system using the same" / 凝縮用熱変換装置, applicant 株式会社ＨＡＲＡ ＴＥＣＨ and 原 隆雄, PCT/JP2006/318947, priority JP 2005‑278949 of 2005‑09‑26, filed 2006‑09‑25, published 2007‑03‑29.
• Disclosure: a condensing heat converter comprising (i) an isobaric cooling unit cooling hot high-pressure gas under isobaric change, (ii) a pressure-reducing liquefying unit that liquefies refrigerant "by an acceleration phenomenon of the refrigerant," and (iii) a pressure-reducing cooling unit that further reduces pressure and enthalpy "by the acceleration phenomenon." The flow passages are progressively narrower in that order (claim 2); the flow velocity in the pressure-reducing/liquefying unit is twice or more that of the isobaric cooling unit (claim 3); the liquefying and cooling units are spiral tubes; an expansion unit may sit between stages; preferred cross-sectional areas are 40–50% and 20–30% of the isobaric unit. Assignee of the US sibling was later recorded as ETL CORPORATION (Reel/Frame 037431/0515, effective 2015‑11‑05).
• § 102 analysis: published 2007‑03‑29, more than a decade before 2018‑03‑13 → fully available as § 102(a)(1) art. However, it discloses only a refrigeration (cooling) circuit — compressor → condenser → converter → evaporator. It contains no four-way valve, no reversible heating mode, no parallel heat-exchange sections, and no pair of on-off valves. It therefore cannot anticipate claim 1 (or claims 2–6, which incorporate claim 1's limitations).
• Where it bites: it is a strong § 103 reference against the "acceleration phenomenon / helical coil / ≥2× flow rate / narrower-in-sequence" concepts, and its claim 3 (≥2× flow velocity) maps closely onto the ratio idea of '757 claim 4 — though note the baselines differ (Hara uses the "isobaric cooling unit" as the denominator; '757 claim 4 uses the heat source side heat exchanger and the use side heat exchanger). It is also relevant background for claim 5.

3.3 WO 2010/082483 A1 — the reversible-cycle Hara reference

• Full citation: WO 2010/082483 A1, "Velocity-heat converter, heating system utilizing same, and heating and cooling system," inventor/applicant Hara Takao, priority/filing 2009‑01‑13, published 2010‑07‑22. Family: JP4545824B1 (2010‑09‑15, 隆雄 原), JP2010281558A (2010‑12‑16).
• Disclosure (per indexed abstract): a "velocity-heat converter" formed by arranging one or a plurality of series tubes, used in a heating system and in a heating and cooling system; the JP sibling abstract notes the converter is "formed by arranging one or a plurality of series tubes in which a…" (text truncated in my search results).
• § 102 analysis: fully available as § 102(a)(1) art (published 2010). The title expressly contemplates a heating and cooling system, so unlike WO '034939 it may disclose a reversible circuit — which is why it is the more dangerous of the two Hara references on the claim-1 question. But I must be candid: I did not obtain the claim set or the drawings, so I cannot state whether it discloses (a) a four-way valve, (b) parallel heat-exchange sections between the heat source side heat exchanger and the expansion valve, or (c) the two on-off valves. Until that text is read, the honest position is that WO '82483 is a candidate for § 102(a)(1) art against claim 1, unverified. This is the highest-priority document to pull in full.

3.4 JP 2013‑122363 A — Patent Literature 1 (the specification's own, and only, admitted prior art)

• Full citation: JP 2013‑122363 A, "Refrigerating device" (冷凍装置), applicant Ｅ・Ｔ・Ｅ株式会社, priority/filing 2011‑12‑12, published 2013‑06‑20.
• Disclosure (as characterized in the '757 specification itself): connecting two coils in series to the inter-unit piping to improve energy efficiency; per the '757 background, it "can only improve energy efficiency during cooling." Crucially, the '757 specification states that in this prior art "the inner diameter of the heating-purpose coiled narrow tube and the inner diameter of the cooling-purpose coiled narrow tube are set to be equal," and that the resulting problem is that the refrigerant temperature "becomes too low when the pressure is reduced in the heating-purpose coiled narrow tube during heating."
• § 102 analysis: fully available as § 102(a)(1) art (published 2013‑06‑20, before 2018‑03‑13). It squarely discloses the series two-coil subcooling arrangement that corresponds to '757 claim 2 (cooling-side wide + narrow tube) and to the coil-winding concept of claim 5. It cannot anticipate claim 1 or claims 3–4/6 because it lacks, on the specification's own admission, the wider heating-purpose narrow tube — the very limitation the '757 drafter used to differentiate. Treat it as the primary § 103 reference, combined with WO 2007/034939 A1 or WO 2010/082483 A1 for the acceleration-phenomenon teaching.

4. Tier 2 — remaining citations, with § 102 assessment

None of the following appears to be an anticipation reference against claim 1 on the material I have; several are plausibly mere background art, and one is likely noise.

5. Claim-by-claim § 102 matrix (against the closest single references)

Notation: ✔ = limitation disclosed (or strongly indicated); ? = unverified; ✘ = not disclosed. Anticipation requires ✔ in every row for a given reference.

Derived verdicts:

• Claim 1 — no confirmed anticipation. The only reference that even arguably reaches it is WO 2019/155644 A1, and only via § 102(a)(2), subject to the § 102(b)(2)(C) common-ownership exception. Every other reference fails on at least the "heating narrow tube wider than cooling narrow tube" limitation.
• Claim 2 (cooling-purpose coiled wide tube added) — potentially anticipated only by a reference that also carries all of claim 1: candidates are WO 2019/155644 A1 (explicitly discloses a cooling coiled wide tube) and, for the coil concept, WO 2007/034939 A1 / JP 2013‑122363 A. No confirmed single-reference anticipation.
• Claim 3 (heating-purpose coiled wide tube added) — potentially anticipated only by WO 2019/155644 A1 (it expressly recites a heating-purpose coiled wide tube). Unconfirmed pending full text.
• Claim 4 (≥2× flow-rate ratios vs. heat source side / use side heat exchangers) — closest disclosure is WO 2007/034939 A1 claim 3 (≥2× flow velocity in the liquefying/cooling units relative to the isobaric cooling unit, not relative to a heat exchanger). Not a § 102 anticipation; strong § 103 material.
• Claim 5 (coil formed by winding a pipeline of inner diameter set per compressor discharge capacity) — WO 2007/034939 A1 discloses spiral tubes with specified cross-sectional-area ratios, and both Hara references tie dimensions to system capacity in the general sense. Marginal § 102; better as § 103.
• Claim 6 (heat exchange unit integrally accommodating both sections) — no reference of record was verified to disclose an integral retrofit unit; this appears to be a genuine point of novelty. No § 102 anticipation identified.

6. Three legal/technical caveats you should carry into any opinion

1. Dependent claims inherit claim 1. Claims 2–6 all depend from claim 1. A reference can only anticipate claim 2, 3, 4, 5, or 6 if it discloses every limitation of claim 1 as well. My matrix therefore pairs each dependent claim with the claim-1 analysis rather than treating the dependent claims as free-standing — a common error when reading citation tables like the one on this face.
2. The § 102(b)(2)(C) common-ownership question is dispositive for WO 2019/155644 A1. The '757 record shows assignment to E.T.L. Corporation (Reel/Frame 053714/0127), and WO '5644's applicant of record is 株式会社Ｅ・Ｔ・Ｌ. If common ownership at 2018‑03‑13 is provable, the strongest reference on the list drops out entirely. Note the same ownership logic now applies to the Hara lineage: the US sibling of WO 2007/034939 A1 was recorded as assigned to ETL CORPORATION in 2015 — so the patentee plausibly owns its own closest "prior art." That is unusual and materially helpful to the patentee.
3. The "acceleration phenomenon" is the patentee's borrowed doctrine, and I am reporting it, not endorsing it. The phrase and its supporting theory — that enthalpy is converted to velocity energy in a helical coil producing decompression, enthalpy reduction, and a "static temperature drop" — are lifted verbatim in concept from the Hara family (WO 2007/034939 A1 describes liquefying refrigerant "by an acceleration phenomenon of the refrigerant… accompanied by pressure reduction and enthalpy decrease"). I take no position on whether that thermodynamic explanation is correct; a validity or infringement theory built on it should be supported by the patentee's own test data (the ~16% savings figure) rather than by the mechanism narrative.

7. What I would do next (and what I could not do)

• Read in full, first: WO 2019/155644 A1 (claims + FIG. 1) and WO 2010/082483 A1 (claims + drawings). These are the only two references on the list that could conceivably reach claim 1 under § 102. Both are freely accessible at patents.google.com.
• Also read: US 2008/0245098 A1 (Samsung) and JP 2013‑122363 A — the former because examiner citations are typically the closest art, the latter because it is the specification's own admitted prior art.
• Confirm ownership: the E.T.L. / 株式会社Ｅ・Ｔ・Ｌ / Ｅ・Ｔ・Ｅ株式会社 chain and the Hara-to-ETL assignment, for the § 102(b)(2)(C) analysis.
• Could not do: I was unable to execute a live USPTO PatentCenter/PAIR or Global Dossier fetch for the file wrapper of 16/978,975 (the actual IDS submissions, the examiner's § 102/§ 103 rejections in the 2021‑10‑12 non-final action, and the applicant's 2022‑01‑07 response). That wrapper is where the applied art is identified with citation categories, and it is the single most valuable document for this question. Note also that the '757 specification's own background section cites only JP 2013‑122363 A — so most of the references in the table came in through IDS or examiner search, not the drafter's admission.

Uncertainty statement: High confidence in the bibliographic data, dates, and citation inventory above (taken verbatim from the granted patent's record and, for WO 2007/034939 A1 and WO 2019/155644 A1, from the WO publications themselves). Low-to-moderate confidence in the § 102 characterizations of JPS6073073U, JPH08200890A, KR0156386B1, JP2000213822A, KR20040086294A/US 2005/0011215 A1, US 2008/0245098 A1, US 2015/0204552 A1, and JP 2013‑122363 A, because my search budget was exhausted before I could read those documents and I relied on the titles and metadata carried in the patent's citation tables. I have marked each such instance "unverified" rather than guessing at content.

I'll ground this analysis by pulling content on the specific references listed in the patent's Prior Art / Citations section.

Let me pull the primary reference (PL1 = JP 2013-122363) and the sibling E.T.L. filing, plus a couple of the parallel-circuit references.

Obviousness Analysis — US 11,371,757 B2 under 35 U.S.C. § 103

Patent: US 11,371,757 B2, "Heating and cooling system" (E.T.L. Corporation); app. 16/978,975; effective filing/priority 2018‑03‑13; issued 2022‑06‑28; 6 claims (claim 1 independent).
Source of record: https://patents.google.com/patent/US11371757/en (fetched 2026‑09‑24), including its "Citations (11)," "Family Cites Families (8)," "Patent Citations (18)," and "Citation List / Patent Literature 1 (JP 2013‑122363)" sections.

Method note / scope limitation. The instruction was to build the analysis from the Prior Art section of the patent page. I retrieved and verified the substantive text of several of those references (JP 5,485,602 B2; JP 5,537,573 B2; WO 2007/034939 A1; WO 2010/082483 A1; US 2008/0245098 A1), but I was not able to retrieve the full text of the primary reference JP 2013‑122363 A, nor of JPS6073073U, JPH08200890A, JP2000213822A, KR100812777B1, KR20040086294A, or CN100580345C before my search budget was exhausted. Where I rely on those, I say so and mark the mapping as unverified. The strongest grounds below rest on references I did verify plus the '757 specification's own admissions about the prior art.

1. Legal framework applied

Under Graham v. John Deere / KSR Int'l v. Teleflex and MPEP 2141–2144, I evaluate: (a) scope and content of the prior art; (b) differences between the prior art and the claims; (c) level of ordinary skill; and (d) objective indicia. Obviousness may be established by (i) combining prior-art elements per known methods to yield predictable results, (ii) simple substitution of a known element, (iii) use of a known technique to improve a similar device in the same way, (iv) applying a known technique to a known device ready for improvement, (v) "obvious to try" among a finite number of predictable solutions, and (vi) optimization of a result-effective variable through routine experimentation (MPEP 2144.04; In re Boesch, In re Aller).

2. Level of ordinary skill in the art (POSITA)

A POSITA here is a refrigeration/HVAC engineer with a bachelor's degree in mechanical engineering (or equivalent) and roughly 2–5 years of experience designing vapor-compression heat pump / air-conditioning refrigerant circuits, including selection of expansion devices, liquid-line components, and refrigerant piping/coil sizing. That person is familiar with: reversible (four-way-valve) heat pump circuit topologies; the use of solenoid/on-off valves to isolate parallel branches; and the standard practice of sizing throttling passageways against the compressor's discharge capacity and the cycle's refrigerating capacity — a practice the '757 specification itself acknowledges (col. describing inner diameters "determined based on various specifications such as a discharge capacity of the compressor").

3. Scope and content of the prior art of record on the page

4. The critical admission already in the specification

Before mapping references, note that the '757 specification concedes the prior-art architecture almost in full:

• Background: reversible systems having "a heat source side unit provided with a compressor, a four-way valve, and a heat source side heat exchanger, and a use side unit provided with a use side heat exchanger … connected … in a loop configuration by inter-unit piping" are "conventionally … known," and PL1 already "connect[s] two coils in series to the inter-unit piping" to improve energy efficiency.
• Detailed description: in PL1, "the inner diameter of the heating-purpose coiled narrow tube 61 and the inner diameter of the cooling-purpose coiled narrow tube 52 are set to be equal," so "an efficient operation can be performed during cooling, but there is a problem that the temperature of the refrigerant becomes too low when the pressure is reduced in the heating‑purpose coiled narrow tube 61 during heating."

That is (i) a § 102-type admission that everything except the relative diameter of the two narrow tubes is old, and (ii) an express statement of the problem and its cause (over-restriction in the heating-mode coil), which frames the sole claimed difference as a result-effective variable (passage width) adjusted against a recognized, well-characterized objective (suppress temperature drop during heating). This admission alone shifts a heavy burden onto the applicant to rebut obviousness.

5. Claim 1 — limitation-by-limitation mapping

Result: every element of claim 1 is disclosed or suggested by the verified art plus the specification's own admissions; the only distinguishing feature is the relative width of the two coiled narrow tubes, which is a one-variable optimization of a tube diameter against a stated performance objective.

6. Grounds of rejection

Ground A (strongest) — JP 2013‑122363 A in view of WO 2010/082483 A1 (Hara), optionally with JP 5,485,602 B2

Rationale: (1) PL1 discloses the reversible architecture, the two-coil series liquid-line arrangement, and heating- and cooling-purpose coiled narrow tubes of equal diameter; it addresses cooling efficiency but (per the '757 admission) leaves heating over-throttled. (2) WO 2010/082483 teaches a velocity-heat converter for both modes having a spiral narrow tube and a spiral wide tube larger in diameter than the narrow tube, and teaches that the passage size controls the balance between pressure drop and temperature drop, which in turn determines whether the heating-mode vaporization condition or the cooling-mode liquefaction condition is obtained. (3) A POSITA seeking to solve PL1's heating defect would enlarge the heating-mode flow passage relative to the cooling-mode passage — the precise claimed relationship — because the reference art teaches this is the lever that suppresses the undersired temperature drop.

KSR rationales engaged: combination of known elements with predictable results; use of a known technique (mode-specific passage sizing in a spiral converter) to improve a similar device (a reversible system with two-coil liquid-line sections) in the same way; applying a known technique to a known device ready for improvement; and optimization of a result-effective variable (MPEP 2144.04).

Ground B — JP 5,485,602 B2 (or WO 2007/034939 A1) in view of a conventional reversible heat pump (JP 2013‑122363 A / JPS6073073U / US 2005/0011215 A1)

JP 5,485,602 supplies: the helical/spiral coil, the "acceleration phenomenon," the enthalpy→velocity-energy "static temperature drop" mechanism, the two-coil series structure, the "≥2×" flow-rate relationship, and the admissible inner-diameter ranges (2–150 mm; desirably 2–50 mm; liquefier 40–50%, subcooler 20–30% cross-sectional area). Combining that converter with a four-way-valve reversible circuit (with liquid-line branches isolated by on-off valves) yields claim 1 once the heating-branch tube is sized larger than the cooling-branch tube — a modification directly suggested by WO 2010/082483 and further by the simple mechanical fact that a wider passage throttles less.

Ground C — any of A/B in further view of US 2008/0245098 A1 (Samsung)

Samsung independently teaches the motivation to increase liquid-line subcooling upstream of the expansion valve to protect/improve cycle performance ("increased supercooling prevents deterioration of performance of the evaporator"). It supplies an express reason to incorporate a liquid-line subcooling device, reinforcing Grounds A and B for claims 1–2.

Ground D (for the parallel-branch/valve limitations) — plus KR 10‑0812777 B1 and/or JPS6073073U

If the primary reference is not shown to disclose two valve-isolated parallel branches, these references (a "cooling/heating separation heat pump" and a branched multi-room air conditioner) supply the known technique of isolating cooling and heating circuits with switching valves. I flag these as unverified because I could not retrieve their text; a rejection relying on them should be built only after confirming their actual disclosures.

7. Motivation to combine — why a POSITA would have done this

1. Same field, same problem, same art. PL1, JP 5,485,602, WO 2007/034939 and WO 2010/082483 all concern liquid-line "velocity-heat"/spiral-coil devices for vapor-compression HVAC. The combination is within a single field of endeavor, and indeed WO 2010/082483 is itself a heating-and-cooling system reference.
2. Art teaches the claimed variable is the control knob. WO 2010/082483 states that the pressure-drop/temperature-drop balance governs whether the heating-cycle vaporization condition or the cooling-cycle liquefaction condition forms. If the heating branch is over-cooling the refrigerant (PL1's admitted problem), the disclosure directs the designer to the passage size.
3. Solution is a simple, predictable parameter change. Enlarging a flow passage reduces throttling, reduces pressure drop, and reduces the "static temperature drop"; the '757 specification itself describes the claimed benefit in these exact, deterministic terms ("the temperature drop inside the heating-purpose coiled narrow tube is suppressed … the refrigerant flows into the heat source side heat exchanger while maintaining a relatively high temperature"). A predictable consequence of a known design change is the paradigm case for § 103.
4. Finite, enumerated design space. The references give explicit numerical guidance (2–150 mm; desirably 2–50 mm; liquefier 40–50% / subcooler 20–30% of a reference cross-section; ≥2× flow-rate design). Selecting a heating-mode diameter above a cooling-mode diameter is one choice among a small, identified set — the "obvious to try" situation of KSR.
5. Commercial/market pressure. The '757 priority is 2018; reversible heat pumps with liquid-line subcooling devices were well known, and improving heating-mode COP is a recognized long-standing objective. That is a classic "design incentive" rationale.
6. Recognized technique, no change in principle of operation. Adding mode-specific branches and isolating them with on-off valves is the standard way reversible circuits direct flow; the claimed system performs the same function (throttling + subcooling in cooling, partial vaporization in heating) with the same components.

8. Reasonable expectation of success

High. The references teach both the structure (helical coil converter with a narrow tube and a larger wide tube) and the operative theory (acceleration → enthalpy-to-velocity conversion → static temperature drop) that the '757 patent relies on. No reference teaches away from mode-specific sizing; to the contrary, WO 2010/082483 distinguishes the heating mode from the cooling mode in both function and sizing.

9. Dependent claims 2–6

• Claim 2 (cooling-purpose wide tube upstream of the cooling-purpose narrow tube): squarely disclosed by JP 5,485,602 B2 (spiral tube 6 before spiral narrow tube 8), WO 2007/034939 A1, JP 5,537,573 B2, and WO 2010/082483 A1 (widely-known narrow+wide combination for the cooling/liquefaction path); also, if PL1 indeed "connect[s] two coils in series," by PL1 itself. This claim is very close to anticipated — see the ¹ caveat below.
• Claim 3 (heating-purpose wide tube downstream of the heating narrow tube): disclosed by WO 2010/082483 A1, cl. 17 (heating: medium passes the narrow tube, vaporization conditions form, then the wide tube completes vaporization). Strong.
• Claim 4 (flow rate of each heat exchange section ≥ 2× that of the corresponding heat exchanger): disclosed by JP 5,485,602 B2 / JP 5,537,573 B2, which specify that the spiral-tube flow velocity should be "2倍以上" the mini heat exchanger's and that the narrow tube's should be equal or higher. Strong; aside from explicit disclosure, it is a design-optimization limit with an articulated reason (acceleration effect).
• Claim 5 (tube inner diameter set according to compressor discharge capacity): routine design; JP 5,485,602 B2 says diameters "are determined by specifications such as the refrigerating capacity." Also the '757 spec admits this is conventional ("determined based on … a discharge capacity of the compressor"). Obvious as a result-effective variable optimization; note the claim recites no numerical boundaries, so no criticality argument attaches.
• Claim 6 (integral heat exchange unit housing both sections): the weakest ground. It recites a packaging/assembly choice (a module, retrofit via connecting piping 71/72). Obvious as an obvious design/manufacturing choice under MPEP 2144.04 and KSR (a mere change in packaging location/shape with no new functional result), but I could not identify a cited reference that discloses the integral unit; a rejection here is best supported with a secondary reference on modular HVAC accessories or with the "known technique / predictable result" rationale.

¹ Note on anticipation vs. obviousness for claim 2: if JP 2013‑122363 A in fact discloses the two-coil series liquid-line structure with a wide tube and a narrow tube as the '757 specification describes, claim 2 may be anticipated under § 102, not merely obvious. This cannot be concluded without the PL1 text.

10. Anticipated patent-owner rebuttals and how they fare

1. "Teaching away — the references require the narrowest feasible tube to maximize acceleration." This is the owner's best argument: the entire Hara/E.T.L. corpus emphasizes that smaller cross-section → higher velocity → greater enthalpy-to-velocity conversion. But (a) that guidance is given for the cooling/liquefaction path, and (b) WO 2010/082483 expressly contemplates that the pressure-drop/temperature-drop balance can be tuned so that either vaporization (heating) or liquefaction (cooling) conditions form — i.e., the reference does not require identical sizing across modes. A teaching-away argument therefore requires the owner to show the references criticize, discredit, or otherwise discourage mode-specific sizing; nothing retrieved does that.
2. "Criticality of the 8–12 mm / 15–33 mm ranges." The claim recites only a relative relationship ("wider"), not any numerical range, so range-criticality evidence for the specification's example numbers is not coextensive with the claim and cannot rebut the claim's obviousness (no nexus).
3. "Unexpected results — 16 % energy savings." The 16 % figure is asserted in the specification without supporting data, and on the face of the patent it relates to cooling, i.e., to the subcooling section that the record shows PL1 and JP 5,485,602 already provide. There is no comparative data anywhere in the patent comparing heating performance with equal-diameter tubes versus the claimed wider heating-mode tube. Under MPEP 716.02, a bare assertion of advantage, without factual evidence of a difference attributable to the claimed feature, does not rebut a prima facie case.
4. "The parallel branches with two on-off valves are not shown." Even if the primary reference lacks them, that limitation is met by standard reversible-circuit practice plus references such as KR 10‑0812777 B1 / JPS6073073U (subject to verification), and its inclusion is a predictable arrangement of known elements with the known function of flow switching.
5. Common-ownership shield for WO 2019/155644 A1. Because that sibling E.T.L. application has a 2018‑02‑09 priority (before the '757 effective filing date) but published after it (2019‑08‑15), it can only be § 102(a)(2) art — and the § 102(b)(2)(C) exception appears to remove it, since the subject matter and the '757 invention were both owned by E.T.L. Corporation. I would not build a § 103 ground on WO 2019/155644 A1. (A related but distinct exposure for E.T.L. is obviousness-type double patenting over its own earlier claims; that is a separate doctrine from § 103 and is outside this analysis.)

11. Overall assessment

12. Confidence and caveats

• High confidence: the content of JP 5,485,602 B2, WO 2007/034939 A1, WO 2010/082483 A1 (cl. 17, 21), and US 2008/0245098 A1, which I retrieved directly; and the '757 claim language and specification admissions (from the full patent text).
• Low confidence: the exact disclosure of JP 2013‑122363 A, JPS6073073U, JPH08200890A, JP2000213822A, KR 10‑0812777 B1, KR 20040086294 A, and CN 100580345 C. My characterization of PL1 comes from the '757 specification's own description (an admission, therefore usable, but not a substitute for the document itself). A definitive § 103 opinion — and certainly any office action or invalidity contention — must be built on the full text of JP 2013‑122363 A, because if PL1 discloses the parallel branches and on-off valves as well, claim 1 reduces to a single, plainly obvious dimensional difference.
• No correction of identifiers: all patent numbers above are reproduced exactly as they appear in the '757 page's citation lists; where a listing on that page appears noisy (e.g., KR 10‑1856239 B1, an LCD-device patent, and US 2015/0204552 A1, an evaporative media system), I have treated them as not pertinent to this subject matter rather than silently reassigning them.
• Not addressed here: patentable subject matter, § 112 written-description/enablement issues (relevant to the claim's functional "acceleration phenomenon" language), and double patenting — all separate from § 103.