US 11371760

I'll search for litigation and docket information on this specific patent number, then summarize from the authoritative patent text provided.

Let me run a couple more targeted searches for litigation/docket activity on this specific patent.

Search results: litigation / CAFC check

I ran targeted web searches for this specific number across litigation databases and CAFC-related sources. I found no CAFC 2026 docket, no district court complaint, and no PTAB proceeding involving U.S. Patent No. 11,371,760. Google Patents' record for the patent likewise shows no litigation section — only "Families Citing this family (5)" and a normal chain of legal events (assignment, notices of allowance, issue-fee payment, patent grant, maintenance-fee reminder dated 2026-02-16).

Caveats on that negative result:

• This was open-web searching, not a direct PACER / Docket Navigator / CourtListener docket query, so I cannot certify exhaustively that no suit exists. I found no evidence of one.
• Several hits were false positives from similar-but-different identifiers, which is worth flagging explicitly under the "interpret identifiers literally" rule:
  • US application 11/371,760 (published as US 2007/0211674 A1, "Auto continuation/discontinuation of data download and upload…") — an application number, unrelated.
  • JP application 11371760 (Toshiba, data transfer method; EP 1113644) — a Japanese application number, unrelated.
  • IPR2023-00957 (Mitsubishi Electric v. TCL) involves different patents ('656, '068, '976) and is unrelated to this refrigeration patent.

If authoritative docket confirmation is required, a PAIR/PatentCenter and PACER/Docket Navigator lookup should be run directly.

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Summary of US 11,371,760 B2

Bibliographic data (from the authoritative patent text):

Abstract (verbatim): "In a refrigeration cycle apparatus according to the present invention, a non-azeotropic refrigerant mixture is used. The refrigeration cycle apparatus includes a compressor, a first heat exchanger, a decompressor, a second heat exchanger, a third heat exchanger, and a blower. The blower blows air to the second heat exchanger and the third heat exchanger. The non-azeotropic refrigerant mixture circulates in a first circulation direction through the compressor, the first heat exchanger, the decompressor, the second heat exchanger, and the third heat exchanger. The second heat exchanger is greater in flow path resistance than the third heat exchanger. The blower forms a parallel flow with the non-azeotropic refrigerant mixture that flows through the second heat exchanger and the third heat exchanger."

Independent claim 1 — plain-language overview

A refrigeration cycle apparatus that runs on a non-azeotropic refrigerant mixture, comprising a compressor, a first heat exchanger, a decompressor, a second heat exchanger, a third heat exchanger, and a blower, with these requirements:

1. Circuit order (first circulation direction): the refrigerant mixture circulates through compressor → first heat exchanger → decompressor → second heat exchanger → third heat exchanger. Per the specification, this is the heating mode, in which the second and third heat exchangers both act as evaporators (outdoor side) and the first heat exchanger acts as the condenser (indoor side).
2. Asymmetric flow resistance: the second heat exchanger has greater flow path resistance than the third heat exchanger (in the embodiment, achieved by the second exchanger having fewer parallel heat-transfer tubes — e.g., 2 vs. 4). The higher-resistance second exchanger sits upstream and the lower-resistance third exchanger downstream in the first circulation direction.
3. Parallel-flow air: the blower blows air to both the second and third heat exchangers in a direction that forms a parallel flow with the refrigerant flowing through them (i.e., air and refrigerant move in the same direction through those exchangers in the heating mode).
4. Enthalpy-split limitation: the enthalpy difference across the second heat exchanger (mixture in vs. out) must be greater than the enthalpy difference across the third heat exchanger. (Note: this limitation appears in claim 1 but is not reflected in the abstract.)

Stated purpose/effect: With a non-azeotropic mixture, the temperature of the refrigerant entering an evaporator is lower than at its outlet because of the mixture's temperature gradient — which promotes frost near the inlet port. By making the upstream (second) exchanger the high-resistance one, the pressure drop occurs where the refrigerant is still relatively warm in the early part of evaporation, so the entering temperature is raised relative to a single-undivided coil, while the suction temperature (and hence capacity) is maintained. Parallel flow with the air further supports frost suppression; reduced defrost frequency improves user comfort, and the COP is reported at parity or better when the tube-count ratio (third:second) is ≥ 2 (Fig. 8).

Dependent claims (brief)

• Claim 2 — the mixture includes HFC32 at ≤ 46 wt % (stated to give GWP ≈ 300).
• Claim 3 — the second exchanger has at least one parallel heat-transfer tube and the third has a plurality of parallel tubes, with the second having fewer tubes than the third (the structural way of creating the greater flow-path resistance).
• Claim 4 — the third exchanger's tube count is ≥ 2× the second's.
• Claim 5 — adds a flow-path switching valve (four-way valve) that reverses circulation to a second direction (cooling/defrost), in which the blower then forms a counterflow with the refrigerant through the second and third exchangers.
• Claim 6 — the second and third exchangers are arranged orthogonal to the blower's air-blow direction.
• Claim 7 — adds a fourth exchanger between the second and third, with resistance intermediate between them, also in parallel flow and orthogonal to the air direction.
• Claim 8 — adds an on-off valve at the compressor discharge, a check valve at the node between the first exchanger and the decompressor, plus fourth and fifth heat exchangers wired in series between the on-off valve and check valve, arranged upstream of the second and third exchangers respectively along the air direction; the controller opens the on-off valve in the first circulation direction and closes it in the second.

Family / counterpart notes

PN: WO2020021700A1 (PCT, per the record marked "Ceased"/not active); EP3832227A1 (recorded as withdrawn); CN112424541B (granted 2022-05-17); JP7184897B2 (granted 2022-12-06). The relevant cited prior art includes WO2015/151289 (PTL 1, Mitsubishi) and US 10,161,652 B2.

Uncertainty: Bibliographic data, claims, and abstract above are taken from the authoritative patent text supplied and are high-confidence. The litigation/docket finding is the only genuinely uncertain item — it is a negative search result from web sources, not a certified docket query.

I'll search for litigation involving US patent 11371760 specifically.

Initial searches returned unrelated results. Let me search more targeted litigation databases.

No litigation found yet. Let me try more specific searches on litigation databases and the patent number in various formats.

Litigation Search Report — U.S. Patent No. 11,371,760

Patent identification (confirmed):

• Patent No.: US 11,371,760 B2 — "Refrigeration cycle apparatus"
• Application No.: 17/057,030 (U.S. national stage of PCT/JP2018/028221, filed July 27, 2018; WO2020021700A1)
• Inventor: Takumi Nishiyama
• Current/Original Assignee: Mitsubishi Electric Corporation (assignment recorded Nov. 19, 2020)
• Grant date: June 28, 2022; Anticipated expiration: July 27, 2038

Result: No litigation found.

I searched for litigation involving US 11,371,760 specifically, using the patent number in multiple formats and targeted queries against patent-litigation sources (Unified Patents litigation portal, PACER/Justia, CourtListener/RECAP, RPX/insight, and general litigation databases). I found no district court action, ITC investigation, or Federal Circuit appeal in which US 11,371,760 is identified as an asserted patent. As of today's date (April 26, 2026), I could not identify any case for this specific patent number.

Important caveats (please read):

1. No affirmative record ≠ confirmed non-litigation. My conclusion is based on the searches I could run; it is not a substitute for a paid docket search (e.g., Docket Navigator, Lex Machina, Westlaw Litigation Analytics, or a full PACER/Delaware/Texas docket sweep). A case could exist that is not indexed in the freely available sources I searched.
2. Co-family members are distinct documents. This patent is part of a family (EP3832227, JP7184897, CN112424541, WO2020021700). Litigation statistics or status for those family members do not carry over to US 11,371,760 and should not be reported as if they did.
3. Likelihood assessment. Given that (a) the patent issued recently (June 2022), (b) it is a component/system patent held by an operating company (Mitsubishi Electric) rather than a monetization/NPE entity, and (c) no assertion activity surfaced, it is plausible this patent has never been asserted. That said, this is an inference, not a verified fact.
4. I did not find any PTAB (IPR/PGR) challenge, reexamination, or other post-grant proceeding against this patent either — again, based on the sources searched.

Recommended next steps for a definitive answer: run the patent number through Docket Navigator or Lex Machina; check the USPTO Patent Center "Litigation" tab and the patent's "Global Dossier"/EPO register for litigation notices; and search PACER directly by patent number. If you want, I can attempt additional targeted searches on a specific venue or party.

I'll verify the structured data against live sources before drafting.

Let me run a few more targeted checks before concluding.

Verification performed

I ran the structured ODP data point against live sources before drafting. Results:

• ODP structured block (canonical): "The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest."
• Independent web checks: searches for US11371760 IPR, "11371760" PTAB AIA trial proceeding, "11,371,760" petition, and Mitsubishi Electric + refrigeration-cycle-apparatus challenges surfaced no IPR, PGR, or CBM referencing this patent. The only hits were unrelated IPR literature and the Google Patents family/citation record for the '760 patent itself (https://patents.google.com/patent/[US11371760](/patent/US11371760)/en), which shows foreign family members (JP7184897B2, CN112424541B, EP3832227A4, WO2020021700A1) but no AIA trial history.

I found no proceeding numbers to report, and I will not invent any.

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Proceedings overview

Total AIA trial proceedings on file for US 11,371,760: zero. No IPRs, no PGRs, no CBMs — nothing instituted, nothing denied on the merits, nothing settled, no claims canceled, no claims sustained. All eight issued claims (1–8) are UNTESTED at the PTAB. The defensive posture this gives a defendant is therefore not "the patent has been hardened by surviving IPRs" and not "the claims are dead" — it is "a clean, unworn patent with the full § 102/§ 103/§ 112 invalidity case still available and zero AIA estoppel on the board." Every prior-art ground a defendant can find is still live, and no petitioner has yet burned the art or created a § 315(e)(2) estoppel trap.

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Per-proceeding detail

None to report. There are no proceedings to itemize. I am deliberately not populating the template below with placeholder numbers.

For completeness on what the absence means:

• No institution decisions to read for the panel's reasoning on claims 1–8.
• No Final Written Decisions — so there is no claim-level holding, canceled or sustained, to quote. If an opposing counsel or demand letter tells you claims 1–8 were "confirmed by the PTAB," that is false as of 2026-09-29.
• No settlement / termination events.
• No Federal Circuit appeals from this patent (no CAFC docket, no CourtListener opinion).

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Strategic summary

Claim status. All of claims 1–8 stand as issued on 2022-06-28. Claim 1 is the independent claim and carries the load: compressor, first heat exchanger, decompressor, second heat exchanger, third heat exchanger, blower; first circulation direction through compressor → first HX → decompressor → second HX → third HX; the second heat exchanger greater in flow path resistance than the third; the blower forming a parallel flow with refrigerant through both; and — the limitation added during prosecution that is likely the real battleground — a difference between the enthalpy of the refrigerant flowing into the second heat exchanger and the enthalpy flowing out of it that is greater than the corresponding enthalpy difference across the third heat exchanger. Claims 2–4 are structural/quantitative dependents (HFC32 ≤ 46 wt %; fewer heat transfer tubes in the second HX; ≥ 2× tube ratio). Claim 5 adds a flow-path switching valve and a counterflow condition in the reverse direction. Claim 6 is the orthogonal-placement dependent. Claim 7 adds a fourth intermediate-resistance heat exchanger. Claim 8 is a substantial apparatus claim (on-off valve at compressor discharge, check valve, fourth and fifth heat exchangers in series, controller logic). None of these have been construed by the PTAB, and none has been construed by any court that I could find.

Estoppel landscape — favorable to a defendant. Because no IPR/PGR was ever instituted against this patent, § 315(e)(2) estoppel is a nullity here. A defendant is free to run every printed-publication, patent, and system-art combination it can assemble in district court or the ITC, without the "raised or reasonably could have raised" trap that follows an adverse IPR. Conversely, if you file the first petition and lose, you will be the one estopped. That asymmetry is worth pricing before filing. Note also the one-year clock under § 315(b): if you have been served with a complaint alleging infringement, the petition window is 12 months from service, and joinder under § 315(c) is the only relief valve. Track that date.

Pattern signals. There is no petitioner pattern to detect — the patent has never been challenged at the PTAB. There is no defensive aggregator (Unified Patents or similar) in the chain that I could find. The patent owner is Mitsubishi Electric Corporation (assignment recorded 2020-11-19, effective 2020-10-14), a large operating company — not an NPE — so the demand-letter/troll framing in the task template does not fit the facts. Two further signals worth noting: (1) the patent is a US national-stage entry of PCT/JP2018/028221, so parallel grant JP7184897B2 exists in Japan, and Mitsubishi has demonstrated it will prosecute this family internationally; (2) the anticipated expiration is 2038-07-27 with a maintenance-fee reminder on file dated 2026-02-16, i.e., the owner is actively paying to keep the patent alive. A patent this long-lived that Mitsubishi chooses to enforce will likely attract IPRs eventually — you may simply be early.

Why the zero matters. Well-asserted patents with 16 years of remaining term and a sizeable commercial target almost always draw petitions. The absence of any petition suggests either (a) the patent has not yet been asserted in a forum where an IPR is worth filing, or (b) it is being used as part of a larger portfolio cross-license rather than a standalone litigation weapon. Either way, the first movers get the cleanest shot at the art.

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Recommended next steps

1. Do not assume prior PTAB work exists. There is no FWD to link to, no claim to quote, and no cancellation to lean on. Any defense must be built from scratch on the intrinsic record — the '760 specification, the prosecution history of US 17/057,030 (note the claim-1 enthalpy-difference limitation appears to have been added or narrowed during prosecution; obtain the full file wrapper via USPTO PatentCenter at https://patentcenter.uspto.gov/), and the international search report dated 2018-10-16 from PCT/JP2018/028221, plus the EPO extended search report of 2021-07-01 for EP3832227A1.

2. Front-load claim construction on the enthalpy-difference limitation and on "flow path resistance." Both are functional/result-oriented. "Flow path resistance" is relative between two heat exchangers and will need a construction tied to the spec (the patent ties it to number of parallel heat transfer tubes and to pressure loss). The enthalpy-difference limitation is the most promising § 112 written-description/enablement target and the hardest § 103 target, because the specification gives little guidance on how to measure it. Consider whether the claim requires a specific operating point or measurement convention — an indefiniteness theory under § 112(b) is a live option in district court (unavailable in IPR).

3. If you intend to file an IPR, watch § 315(b) and file early. The prior-art universe is narrow and non-azeotropic-refrigerant mixtures (R32/R1234yf, R32/R1234ze(E), R290, CO2 blends) are extremely well-documented pre-2018. The strongest § 103 theory is likely the serendipity/"result-effective variable" attack on the enthalpy-difference limitation — i.e., that arranging unequal flow resistance in one of two series evaporators to flatten the glide-induced frost gradient is an obvious optimization. Note that Mitsubishi's own earlier work is in the citation record and could be fair game as prior art (e.g., WO2018/002983A1 and its US counterparts US 10,883,745; US 2019/0277549 / US 11,175,080; US 2019/0234643). Those same-family publications are candidates for use against the '760 patent precisely because they were not before the examiner in the same combination. Verify dates and § 102(a)(2)/§ 102(b)(2) status carefully before relying on them.

4. Preserve system art for district court. Because there is no estoppel, you can and should keep hardware/system prior art (actual outdoor-unit product structures with unequal tube-count evaporator banks) out of any IPR and save it for § 282 — IPR estoppel cannot reach system art, and having held it back means nothing was "reasonably could have raised" at the PTAB.

5. Docket monitoring. Set recurring checks on PTAB E2E (https://ptacts.uspto.gov/ptabweb/#/patentSearch) and the USPTO Open Data Portal for US 11,371,760, plus a CourtListener alert for "11,371,760." If an IPR lands before yours, weigh § 315(c) joinder against independent filing, and re-run the § 315(e)(2) analysis the day an FWD issues.

Confidence statement: I am highly confident there is no AIA trial proceeding on US 11,371,760 as of 2026-09-29 — the canonical ODP data says so and my independent searches corroborate it. I did not verify the status of any ex parte or inter partes reexamination (a different statutory track, and not an AIA trial proceeding), nor did I confirm whether any foreign invalidation action (e.g., at the CNIPA or JPO) is pending against family members. If you need those, they must be checked separately — PTAB data will not show them.

I'll attempt to verify the assignment record from public sources before writing up.

Assignment & Ownership Analysis — US 11,371,760 B2 ("Refrigeration cycle apparatus")

Data-integrity note up front. My tooling for this task is web search only; I could not load assignmentcenter.uspto.gov or assignment.uspto.gov interactively to read the assignment cover sheets (which is where the correspondent of record field lives). The reel/frame, conveyance type, parties, and dates below are anchored to the USPTO-derived legal-events record reproduced in the authoritative patent text supplied to me. Where I could not verify a field, I say so rather than filling it in. This is a material gap: the correspondent field — the single most useful NPE tell in your brief — is not retrievable from the sources I could reach, and I will not invent it.

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Inventors

Unusual-pattern check — clean. Single-inventor patent; no inventor departures or co-inventor splits to track. One nuance worth flagging so it is not misread as a red flag: the inventor→company assignment was executed 2020-10-14, more than two years after the 2018-07-27 international filing date. That is normal for a PCT national-stage case — the assignment is typically papered at U.S. entry (the U.S. national stage was entered/recorded 2020-11-19), not a sign of late-stage inventor flight. There is no evidence of any inventor leaving MELCO within 12 months of filing.

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Original assignee

Mitsubishi Electric Corporation (Tokyo; TYO:6503) — the entity named as original assignee on the face of the patent, as the PCT applicant (PCT/JP2018/028221), and as current assignee.

• Primary line of business: diversified electrical/electronics manufacturer. The relevant business unit here is Building Systems / air conditioning, which is one of MELCO's core profit centers.
• Does it ship a product embodying the claims? Yes. The specification expressly frames the apparatus as a residential or commercial unit — "Refrigeration cycle apparatus 100 may be a package air conditioner (PAC) or a room air conditioner (RAC)" — i.e., MELCO's Mr. Slim / City Multi / room-AC product lines, and examples 100C (no four-way valve) map to showcases/refrigerators. This is an operating-company patent on an operating-company product, not a paper asset.
• Current status: operating, listed, solvent. No bankruptcy, no reorganisation, no acquisition.
• Corroborating signals of continuing ownership by the original assignee: Google Patents legal events show no post-issuance transfer; the status is Active with anticipated expiration 2038-07-27; and a maintenance-fee reminder dated 2026-02-16 issued with the owner entity status recorded as large entity / undiscounted — i.e., as of early 2026 a large operating corporation (MELCO's profile) is still the fee-paying owner.
• Counterparts maintained worldwide — JP7184897B2 (granted 2022-12-06) and CN112424541B (granted 2022-05-17), with the EP case recorded as withdrawn and the WO case marked ceased. A live US + JP + CN family with no US-only carve-out is the profile of an operating company, not of a monetisation vehicle.

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Assignment timeline

One (1) recorded assignment exists. There are no post-issuance assignments. Say that plainly — this is the finding.

• 2020-10-14 (executed) / recorded 2020-11-19 — Reel 054424 / Frame 0717 (per the assignment record cited in the patent's legal events: "ASSIGNMENT OF ASSIGNORS INTEREST; ASSIGNOR: NISHIYAMA, TAKUMI; REEL/FRAME: 054424/0717")
  • Conveyance: Assignment
  • Assignor: Takumi Nishiyama (sole inventor)
  • Assignee: Mitsubishi Electric Corporation
  • Correspondent: Not retrievable from the sources available to me. The legal-events rendering of the record does not expose the correspondent field, and I could not open the Assignment Center cover sheet for 054424/0717. I will not guess a name or firm. Flag: this is the one field in your brief's "most useful tell" category that I could not fill — for the reason discussed in the NPE section, its practical importance here is low, because the chain has only one link and no anonymous LLC in it.
  • Context: Standard inventor → employer assignment — the routine title-cleaning paper executed at U.S. national-stage entry (recorded the same day the national stage was filed, 2020-11-19), enabling the U.S. filing to proceed in MELCO's name. Not an acquisition, fire-sale, reorg, securitisation, or transfer-to-asserter.

Post-issuance activity: none. No assignment executed on or after the 2022-06-28 grant date. The ownership chain terminates at the original assignee.

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Timeline diagram

timeline
    title Ownership of US 11371760
    2018 : PCT filed by Mitsubishi Electric
    2020 : Inventor assignment executed Oct 14
         : Recorded at USPTO Nov 19
         : US national stage entry
    2022 : Patent issued Jun 28
    2026 : Maintenance fee reminder Feb 16

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NPE / troll-pattern signals

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Verdict

Insufficient data — applying your definition literally ("no records, or only the original assignment"): the chain contains exactly one recorded assignment, Reel 054424/0717 (exec. 2020-10-14, rec. 2020-11-19), which is the routine inventor→employer paper, and I could not retrieve the correspondent field that your framework treats as the key diagnostic.

I want to be explicit that this verdict is a bucket artefact, not genuine ambiguity about ownership. Ownership is well established and is the opposite of an NPE pattern: Mitsubishi Electric Corporation is the original, current, and only assignee; it pays maintenance fees as a large entity (reminder dated 2026-02-16); it maintains a live multi-jurisdiction family (JP7184897B2, CN112424541B); and it sells the very product class the claims cover. On the merits, seven of the eight signals are affirmatively not present and the eighth is untestable. Because the framework's other four verdicts each require an assertion event or a transfer that does not exist here ("operating-company assertion" presupposes suing competitors — MELCO is not doing so over this patent), Insufficient data is the only definitionally available choice.

Verify directly: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (mirror index: https://assignment.uspto.gov/patent/index.html) — search by Patent Number 11371760, and pull the 054424/0717 cover sheet specifically to capture the correspondent of record. Also worth a PACER/Docket Navigator pass on the refrigeration/VRF defendants to confirm the negative litigation finding from the prior section.

I'll verify the citation record and pull details on the key references before mapping them to claims.

Let me pull details on the highest-relevance cited references.

Prior-Art Analysis — US 11,371,760 B2 ("Refrigeration cycle apparatus")

0. Method, sources, and the limits of what I actually verified

On the USPTO-database instruction: I was unable to complete a direct USPTO (PatentCenter / PatFT) query in this session. The searches I ran returned Google Patents and EPO mirrors, not USPTO-native records. The citation list I work from below is therefore taken from the authoritative patent text supplied in this analysis — which is the Google Patents rendering of the USPTO record for US 11,371,760 (source: https://patents.google.com/patent/US11371760/en). That record's citation tables are the closest thing to a USPTO citation listing I have, and I treat them as authoritative per the operating rules. I flag this explicitly rather than implying I pulled these 41 rows straight from PatentCenter.

Two citation lists appear in the record, and they are not identical:

The two lists overlap in substance but the 41-row list is the operative one for a US § 102/§ 103 analysis. I analyze both.

Two record anomalies I will flag rather than smooth over (per "interpret identifiers literally"):

1. US 2020/0173696 A1 (Hefei Midea) is listed with priority/filing date 2018-10-22 — after this patent's 2018-07-27 effective filing date. It therefore cannot be § 102(a)(1) or § 102(a)(2) prior art to US 11,371,760. Its presence in the list is likely an artifact of citation aggregation across the family (e.g., an IDS in a later, related case), not a § 102 reference. Treat it as non-prior-art.
2. Every other citation predates 2018-07-27 and is facially eligible as prior art (all are printed publications, § 102(a)(1), or US applications/patents under § 102(a)(2)).

Critical framing for the § 102 question. Claim 1 is a narrow combination claim. To anticipate claim 1 under § 102, a single reference must disclose all of:

• (a) a non-azeotropic refrigerant mixture;
• (b) compressor + first HX + decompressor + second HX + third HX + blower;
• (c) circulation in the first direction through compressor → first HX → decompressor → second HX → third HX (series, second upstream);
• (d) second HX greater in flow-path resistance than third HX;
• (e) blower forming a parallel flow with the refrigerant through both the second and third HX; and
• (f) the enthalpy-difference asymmetry (Δh across second HX > Δh across third HX).

My bottom line, stated up front: based on the titles, families, abstracts and bibliographic data available to me, no single cited reference anticipates claim 1 under § 102, and because every dependent claim 2–8 incorporates claim 1's limitations, none anticipates the dependent claims either. These are § 103 (obviousness) references in combination. I say this with high confidence on the claim-1 combination point and lower confidence on the individual foreign references, whose full texts I could not retrieve (see caveats in §5).

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1. Tier 1 — The references that actually drove the case (highest relevance)

1.1 WO 2015/151289 A1 — PTL 1, the only reference discussed in the specification

• Citation: WO 2015/151289 A1, Mitsubishi Electric Corp. (三菱電機株式会社), "Air-conditioning device" / "Air-conditioning device."
• Dates: priority/filing 2014-04-04; published 2015-10-08.
• Description: This is the "PTL 1" of the background section. It discloses an air-conditioning apparatus usable with a non-azeotropic refrigerant mixture such as R-407C, in which the heat-source-side heat exchanger includes a first heat-exchange unit and a second heat-exchange unit; when the outlet temperature of the first unit exceeds that of the second, the flow rate of the heat medium through the first unit is reduced, so that defrosting ability is made uniform across the heat-source-side exchanger.
• Claim mapping / § 102: Relevant to the two-part-outdoor-exchanger concept of claims 1, 5, 6, 7. Not § 102 anticipatory — the specification itself states PTL 1 gives "no consideration … to the temperature decrease near the port of the heat exchanger into which the non-azeotropic refrigerant mixture flows," and it lacks the flow-path-resistance differential (d), the parallel-flow limitation (e), and the enthalpy asymmetry (f). Best characterized as a § 103 reference, and chiefly as the admitted background.
• Note: WO 2015/151289 and US 10,161,652 B2 / US 2017/0108249 A1 (below) are the same Mitsubishi family, so citing both is, in substance, one piece of prior art.

1.2 US 10,161,652 B2 (and US 2017/0108249 A1) — US counterpart of PTL 1

• Citation: US 10,161,652 B2, Mitsubishi Electric Corp., "Air-conditioning apparatus" (pre-grant pub. US 2017/0108249 A1).
• Dates: priority/filing 2014-04-04; US publication 2017-04-20; granted 2018-12-25 (grant date is after this patent's filing, so the § 102 date is the 2017-04-20 publication / 2014 priority).
• Description: Claims a heat-medium circuit with a heat-source-side heat exchanger having a first heat exchange unit and a second heat exchange unit connected to the first; first and second outlet-temperature detecting units; a flow regulating unit to regulate heat-medium flow through each unit; and a control unit that, during defrosting, compares the two outlet temperatures and reduces flow through the first unit when its outlet temperature is higher. Aim is uniform defrosting capacity. Expressly discusses frost build-up in a lower part of an outdoor exchanger.
• Claim mapping / § 102: Structurally relevant to claims 1, 6, 7 (series/discrete outdoor exchanger units; defrost). Not § 102 anticipatory of claim 1 — it works on a heat medium flow-rate regulation, and discloses none of (d)–(f). § 103 reference.
• This is the reference the earlier-generated summary flagged as key cited art; that identification is confirmed here.

1.3 US 11,175,080 B2 / US 2019/0277549 A1 — "heat exchanger switchable between parallel and series connection"

• Citation: US 11,175,080 B2, Mitsubishi Electric Corp. (pre-grant US 2019/0277549 A1), "Refrigeration cycle apparatus having heat exchanger switchable between parallel and series connection."
• Dates: priority/filing 2016-10-28; US pub. 2019-09-12; granted 2021-11-16.
• Description (from title/record): A refrigeration-cycle apparatus in which an outdoor heat exchanger is switchable between parallel and series connection — i.e., the same applicant and field, addressing the series/parallel topology of multiple outdoor exchangers that is central to claim 1's "second upstream / third downstream in series" architecture.
• Claim mapping / § 102: The single most structurally on-point § 103 reference for the series-connection concept of claim 1 (and conceptually relevant to claim 5, where flow direction reverses). Not § 102 anticipatory of claim 1 absent disclosure of the non-azeotropic mixture + flow-resistance differential + parallel flow + enthalpy split. § 103 reference. (I could not retrieve the full text in this session; the description is from the title and family data — see caveats.)

1.4 The Mitsubishi Electric 2016-10-28 cluster

• Citations: US 2019/0257554 A1 / US 10,928,105 B2, "Air conditioner"; US 2019/0277549 A1 / US 11,175,080 B2 (above); plus US 10,928,105 B2.
• Dates: priority/filing 2016-10-28; pubs. 2019-08-22 / 2019-09-12; grants 2021-02-23 / 2021-11-16.
• Claim mapping: Collectively directed to air-conditioner/refrigeration-cycle arrangements of multiple outdoor heat exchangers — relevant to claims 1, 5, 6, 7. § 103 references.

1.5 WO 2018/002983 A1 / US 2019/0137146 A1 / US 10,883,745 B2 — Mitsubishi, "Refrigeration cycle device/apparatus"

• Dates: priority/filing 2016-06-27; WO published 2018-01-04; US pub. 2019-05-09; granted 2021-01-05.
• Description: Same-applicant refrigeration-cycle apparatus; per the citation record it is cited in analogous Mitsubishi refrigeration-cycle cases.
• Claim mapping / § 102: Relevant background to claim 1 (refrigeration-cycle architecture). Not § 102 anticipatory on the record available. § 103 reference. (Full text not retrieved.)

1.6 US 2015/0211772 A1 — Mitsubishi, "Refrigeration cycle apparatus"

• Dates: priority/filing 2012-10-26; published 2015-07-30.
• Description: Mitsubishi refrigeration-cycle apparatus.
• Claim mapping: Relevant to claim 1 generally; no disclosure of (d)–(f) apparent. § 103 reference.

1.7 US 2015/0316275 A1 and US 2015/0338121 A1 — Mitsubishi, "Air-conditioning apparatus"

• Dates: respectively priority/filing 2013-02-19 (pub. 2015-11-05) and 2013-03-12 (pub. 2015-11-26).
• Description: Mitsubishi air-conditioning apparatuses (multiple-outdoor-unit/defrost-adjacent subject matter; US 2015/0316275 A1 corresponds to WO 2014/128830).
• Claim mapping: Relevant to claims 1, 5, 6 (outdoor heat-exchanger arrangement and defrost switching). § 103 references.

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2. Tier 2 — Non-azeotropic-mixture and heat-exchanger references (directly on the preamble/architecture)

2.1 JPH 07-190571 A — "Refrigeration system using non-azeotropic mixed refrigerant"

• Citation: JP H07-190571 A, Matsushita Electric Industrial Co., Ltd. (松下電器産業株式会社).
• Dates: filed 1993-12-24; published 1995-07-28.
• Description: A refrigeration system that uses a non-azeotropic mixed refrigerant — the earliest cited reference whose stated subject matter is a refrigeration system built around a non-azeotropic mixture (i.e., it goes to claim 1's preamble (a)).
• Claim mapping / § 102: Directly relevant to the claim 1 preamble and to the claim 2 refrigerant-composition context. Not § 102 anticipatory of claim 1 absent the heat-exchanger/resistance/parallel-flow/enthalpy limitations. § 103 reference, strongest as evidence that non-azeotropic mixtures in refrigeration cycles were known by 1995.

2.2 JPH 10-068560 A — "Refrigeration cycle device"

• Citation: JP H10-068560 A, Matsushita Electric Industrial Co., Ltd.
• Dates: filed 1996-08-28; published 1998-03-10.
• Description: Refrigeration-cycle device (Matsushita; contiguous in time and assignee with the non-azeotropic work above).
• Claim mapping: Relevant to claims 1, 3 (cycle architecture / exchanger channeling). § 103 reference.

2.3 JPH 11-304292 A — "Air-cooled heat exchanger"

• Citation: JP H11-304292 A, Daikin Industries, Ltd. (ダイキン工業株式会社).
• Dates: filed 1998-04-21; published 1999-11-05.
• Description: Air-cooled (outdoor) heat exchanger — relevant to the structural realization of the second/third exchangers (e.g., parallel heat-transfer tubes, airflow orientation) that underpins claims 3, 4, 6.
• Claim mapping / § 102: Relevant to claims 3, 4, 6; not anticipatory of any full claim on its own (it does not reach claim 1's limitations). § 103 reference for the exchanger-structure dependent claims.

2.4 JP 2012-052676 A and JP 2012-145302 A — Hitachi Appliances

• Citations:
  • JP 2012-052676 A, Hitachi Appliances, Inc., "Heat exchanger and air conditioner using the same" — filed 2010-08-31; published 2012-03-15.
  • JP 2012-145302 A, Hitachi Appliances, Inc., "Refrigeration cycle device" — filed 2011-01-14; published 2012-08-02.
• Description: Heat-exchanger structure and refrigeration-cycle device.
• Claim mapping: Relevant to claims 1, 3, 6 (exchanger construction and placement). § 103 references.

2.5 JP 2009-257740 A (Daikin) and JP 2007-155192 A (Hokkaido Electric Power)

• Dates: JP 2009-257740 A — filed 2008-03-25, pub. 2009-11-05 ("Refrigerating apparatus"); JP 2007-155192 A — filed 2005-12-02, pub. 2007-06-21 ("Refrigeration cycle equipment").
• Claim mapping: General refrigeration-cycle context for claim 1. § 103/background references.

2.6 US 2017/0002245 A1 — Asahi Glass, "Working fluid for heat cycle…"

• Citation: US 2017/0002245 A1, Asahi Glass Company, Limited, "Working fluid for heat cycle, composition for heat cycle system, and heat cycle system."
• Dates: priority/filing 2014-03-18; published 2017-01-05.
• Description: A heat-cycle working fluid/composition — i.e., a refrigerant-blend disclosure, the class of art that bears on the claim 2 limitation (non-azeotropic mixture including HFC32 at ≤ 46 wt %).
• Claim mapping / § 102: This is the citation most directly aimed at claim 2's composition limitation. It does not, however, disclose claim 1's apparatus limitations, so it cannot anticipate any claim on its own (claim 2 incorporates all of claim 1). § 103 reference for claim 2.

2.7 JPH 06-129732 A (Nippondenso) and JPH 09-145076 A (Matsushita) — Family-cites-only

• Dates: JP H06-129732 A — filed 1992-10-14, pub. 1994-05-13 ("Refrigerant condenser"); JP H09-145076 A — filed 1995-11-28, pub. 1997-06-06 ("Heat exchanger").
• Claim mapping: Exchanger/condenser structure; claims 1, 3, 6 context. These appear in the "Family Cites Families" table — i.e., they are cited in the JP/EP/CN family members, so their role in the US prosecution is unconfirmed.

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3. Tier 3 — Control, defrost, and refrigerant-system references (relevant to specific dependent claims)

Family-cites-only (US-prosecution relevance unconfirmed):

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4. § 102 verdict — synthesized

Anticipation requires a single reference disclosing every limitation, arranged as claimed. Applying that test to claim 1's six requirements (§0(a)–(f)):

1. No cited reference discloses the (d)+(e)+(f) triad together — the flow-path-resistance differential between two series-connected outdoor exchangers, the parallel-flow blower orientation, and the enthalpy-split asymmetry. The enthalpy-split limitation (f) in particular is absent from the abstract and, on the record available, from every cited reference; it reads as the applicant's characterization of the physical consequence of (d).
2. The closest single references are structural but incomplete:
   • US 11,175,080 B2 (parallel/series-switchable outdoor exchanger, Mitsubishi, 2016-10-28) — gets to (b)/(c)/(d)-adjacent topology, but not the non-azeotropic-mixture-driven parallel-flow + enthalpy limitations.
   • US 10,161,652 B2 / WO 2015/151289 A1 (PTL 1) — gets to the two-unit heat-source exchanger and defrost-uniformity, but operates on heat-medium flow, and the specification expressly distinguishes it.
3. Conclusion: every citation in the record is best categorized as a § 103 obviousness reference (alone or in combination with another of the same class), not a § 102 anticipatory reference. I found no § 102(a) knockout in the 41-row US citation list or the 9-row family list.

Highest-leverage § 103 combinations to watch (if a validity challenge were mounted):

• US 11,175,080 B2 + US 10,161,652 B2 (series/parallel outdoor-exchanger topology + two-unit heat-source exchanger with defrost control), optionally + JP H07-190571 A (non-azeotropic mixture in a refrigeration system) and US 2017/0002245 A1 (refrigerant composition → claim 2).
• For the claim 2 composition limitation, US 2017/0002245 A1 (Asahi Glass, 2014-03-18) is the most on-point reference in the record.
• For the claims 3–4 tube-count/resistance limitation, JP H11-304292 A (Daikin air-cooled exchanger) and JP 2012-052676 A (Hitachi) are the structural references.

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5. Caveats and honesty flags

1. Full text not retrieved for most foreign references. My descriptions of the Japanese, Chinese, Italian and WO references are derived from titles, assignee, and family/citation metadata in the authoritative record, plus the abstracts I could surface. I could not retrieve the full specifications of JPH 07-190571 A, JPH 10-068560 A, JPH 11-304292 A, JP 2012-052676 A, JP 2012-145302 A, JP 2009-257740 A, JP 2007-155192 A, JPH 06-129732 A, JPH 09-145076 A, or the Chinese/Italian items. My "brief descriptions" for those are title-level and should not be treated as claim-element mappings.
2. The § 102 conclusion is a negative finding, but it is based on incomplete reference texts. The safe, defensible statement is: on the record available, no citation discloses the full claim-1 combination, not "anticipation is impossible."
3. The USPTO-database search was not executed directly (§0). If a certified citation listing is required, run PatentCenter for application 17/057,030 and pull the examiner's form PTO-892 / SB-08 and the "References Cited" box of the printed patent.
4. Date anomaly flagged, not corrected: US 2020/0173696 A1 (2018-10-22) post-dates the 2018-07-27 filing and is not § 102 prior art; its presence in the citation table is unexplained by the record as supplied.
5. No contradiction with the earlier-generated sections on the claim structure (8 claims, 1 independent, 2–8 dependent with 7→5 and 8→6) or on the identification of PTL 1 = WO 2015/151289 and US 10,161,652 B2 as key cited art. The earlier summary's statement that "the relevant cited prior art includes WO2015/151289 (PTL 1, Mitsubishi) and US 10,161,652 B2" is confirmed and extended here — I add that US 11,175,080 B2 ("switchable between parallel and series connection") is arguably the most structurally on-point § 103 reference in the entire list, which the earlier summary did not call out.

I'll research the key prior-art references from this patent's citation list before building the § 103 analysis. Let me run targeted searches.

Obviousness Analysis — U.S. Patent No. 11,371,760 B2

Title: Refrigeration cycle apparatus · Assignee: Mitsubishi Electric Corp. · Inventor: Takumi Nishiyama
Application: US 17/057,030 (national stage of PCT/JP2018/028221) · Effective filing / priority: 2018-07-27
Claims analyzed: 1–8 (1 independent)

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0. Methodology note and evidentiary limits

The task directs me to "use the results from the Prior Art section of this page." What the record supplies is (a) the patent's own Background/Technical Problem discussion of PTL 1, and (b) a citation list of 30 patent documents (plus 9 family citations) identified on the Google Patents page. Google Patents lists titles and dates but generally not full text for the JP/CN/IT citations.

I therefore separated the references into two tiers:

Caveats I want on the record before the analysis:

1. Statements about Tier 2 references are limited to what their titles/assignees/dates support. I have not verified their disclosures and will not assert specific teachings for them.
2. JPS62255071A (Matsushita, 1986, "Refrigeration cycle using non-azeotropic mixed refrigerant") is not in US 11,371,760's citation list. I found it via search. I flag it because I retrieved substantive text and it is highly probative — but it is supplemental art, not "art of record."
3. Date qualification: the critical date is 2018-07-27. One cited document — US 2020/0173696 A1 (Hefei Midea, priority 2018-10-22) — has an effective filing date after the critical date and therefore does not qualify as prior art under AIA § 102. I flag this rather than assuming the citation list is all citable art.
4. Minor date discrepancy: the system date in my instructions is 2026-09-29; the task header says April 26, 2026. Nothing in the analysis turns on this.

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1. Governing law and the person of ordinary skill

Framework. Under Graham v. John Deere Co., 383 U.S. 1 (1966), and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), the inquiry is: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; (4) secondary considerations. A claim is obvious where the differences would have been obvious to a POSITA, and KSR endorses the "predictable results," "simple substitution," "known technique to improve similar devices," and "obvious to try / finite number of identified solutions" rationales (MPEP 2143).

POSITA. I would define the hypothetical skilled artisan as having a B.S. in mechanical engineering (or equivalent) plus 2–4 years of experience in vapor-compression refrigeration/HVAC equipment design, with working familiarity with (i) non-azeotropic (zeotropic) refrigerant blends and their temperature glide, (ii) fin-and-tube heat exchanger construction including parallel-tube/flow-path-count design, (iii) reversing-cycle (heat-pump) architecture including four-way valves and defrost control. This is a routine, well-populated art; the claims recite system architecture, not a chemical or algorithmic invention.

Critical admissions in the specification. Two passages function as applicant admissions and sharply narrow the space for non-obviousness:

• Admission of the problem and its mechanism (Background): "It is known that a non-azeotropic refrigerant mixture has a characteristic (a temperature gradient) that, at constant pressure, the non-azeotropic refrigerant mixture existing as saturated vapor is higher in temperature than the non-azeotropic refrigerant mixture existing as a [saturated] liquid… frost is more likely to be formed near a port of the heat exchanger into which the non-azeotropic refrigerant mixture flows." The patent thus concedes the glide-frost problem was known.
• Admission of the PTL 1 architecture: "In the air conditioning apparatus, a heat source-side heat exchanger includes a first heat exchange unit and a second heat exchange unit. When the outlet temperature of the first heat exchange unit is higher than the outlet temperature of the second heat exchange unit, the flow rate of the heat medium circulating through the first heat exchange unit is reduced…" — i.e., the applicant concedes that splitting the outdoor/source-side heat exchanger into two units and independently regulating the refrigerant flow between them was known.

That second admission is close to dispositive of the structural premise of claim 1.

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2. Claim 1 — element-by-element construction and mapping

Claim 1 has seven distinct requirements. I construe them as follows.

Interpretive flag on E7. The previously-generated summary correctly noted that the enthalpy-split limitation appears in claim 1 but not in the abstract. It also does not appear in the Summary of Invention or in the description of FIGS. 6–7. FIG. 6 shows process C14→C15 across heat exchanger 5a and C15→C1 across 5b, but the specification never compares the two in enthalpy terms. I cannot verify from the record that the disclosed 2-tube/4-tube geometry necessarily produces Δh(5a) > Δh(5b), although it is a plausible and arguably inherent consequence of putting the high-pressure-drop section upstream. This warrants (a) a § 112(a) written-description question and (b) caution in any § 103 rejection resting on inherency. I flag it rather than paper over it.

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3. Ground 1 (primary): WO2015/151289 / US 10,161,652 B2 in view of JPH07190571A and US 2019/0277549 A1

3.1 The primary reference

WO2015/151289 A1 (Mitsubishi Electric) — the patent's own PTL 1. Its U.S. counterpart is US 10,161,652 B2 (granted 2018-12-25); its pre-grant publication US 2017/0108249 A1 published 2017-04-20, i.e., before the 2018-07-27 critical date, making it § 102(a)(1) art.

Verified disclosure:

• Heat medium circuit: compressor 11 → flow switching unit 15 → heat source-side heat exchanger 12 → expansion unit 13 → use-side heat exchanger 14, with the heat source-side heat exchanger comprising a first heat exchange unit 12a and a second heat exchange unit 12b.
• A flow regulating unit 40 that regulates the flow rate of refrigerant through each of the two units — which, in the appliance of claim 1, is the functional equivalent of "second HX greater in flow path resistance than third HX" once the asymmetry is fixed structurally.
• ¶[0027]–[0028]: the two units may be connected in parallel (Emb. 1) or connected in series via coupling pipes 134 (Emb. 2); and the number of branch pipes feeding each unit is deliberately made different.
• ¶[0026]: in heating the source-side HX "serves as an evaporator"; in cooling and defrosting it "serves as a condenser."
• A single air-sending device blows air over the heat source-side heat exchanger (in which both units reside) — satisfying E3.
• ¶[0023]: the working fluid "may be … a zeotropic refrigerant mixture such as R-407C" — satisfying E1.
• ¶[0002] of the patent under analysis confirms the applicant reads PTL 1 as teaching a two-unit source-side heat exchanger with per-unit flow-rate regulation for defrosting.

3.2 The secondary references

JPH07190571A (Matsushita Electric Industrial, publ. 1995-07-28) — "Refrigeration system using non-azeotropic mixed refrigerant." It is listed in the patent's own citation list and its existence/subject matter is confirmed by its citation in EP 2672205 A2. Its relevance is the recognition in the art that a non-azeotropic charge presents a distinct frost-distribution problem — precisely the problem the patent's Background admits was known.

US 11,175,080 B2 / US 2019/0277549 A1 (Mitsubishi Electric; priority 2016-10-28; published 2019-09-12) — "Refrigeration cycle apparatus having heat exchanger switchable between parallel and series connection." § 102(a)(2) art (U.S. application publication effectively filed before 2018-07-27). Verified content:

• Outdoor heat exchanger 5 comprises heat exchange units 5a and 5b; a linear flow path switching valve 12 connects them in series or in parallel.
• Its FIG. 20 = series flow (5b → 5a) during evaporation — the element-E4 ordering.
• It expressly uses non-azeotropic refrigerant mixture and states: "This enables selection of a flow path to reduce a temperature difference between the inlet and the outlet during evaporation depending on the composition of the non-azeotropic refrigerant mixture or operating state."
• It expressly ties that control to frost: "The above control can reduce temperature difference ΔT, thereby suppressing the occurrence of partial frost formation and partial dew condensation."
• Its Embodiment 2 sets a frost-formation determination temperature (e.g., 0 °C) and reduces inlet–outlet ΔT when frost risk exists.

That last cluster of disclosures is the bridge: it shows a POSITA, working with a non-azeotropic mixture in the same assignee's own product line, already understood that the evaporator's inlet–outlet temperature difference drives partial frost, and that splitting the outdoor coil into series units with different flow-path counts is the lever to control it. Element E6's purpose (frost suppression) and element E5's mechanism (flow-path count) are thus squarely in the art.

3.3 Motivation to combine (KSR rationales)

3.4 Element E6 ("parallel flow") specifically

This is the element I would expect the applicant to contest, so let me be precise about the two sides.

Against the applicant:

• Parallel vs. counterflow is a binary, conventional design choice with fully predictable consequences; selecting among a small number of known options for a known purpose is the paradigm KSR case.
• Reversal of refrigerant direction in a heat pump fitted with a single fixed blower inherently converts parallel flow into counterflow (heating) and counterflow into parallel flow (cooling). So E6 is largely an inherent geometric consequence of the reversing-cycle architecture — the applicant says as much: "air blowing direction Ad1 of outdoor fan 7 is defined such that [it] and the direction of the non-azeotropic refrigerant mixture flowing through heat exchangers 5a, 5b form a parallel flow in the heating operation and form a counterflow in the cooling operation."
• The principal recited benefit of E6 is expressly to mitigate a drawback, not to confer a new advantage: "the heat exchange efficiency of heat exchangers 5a and 5b in the cooling operation can be improved while suppressing deterioration in heat exchange efficiency … in the heating operation." A configuration chosen to limit a known loss while optimizing the opposite mode is a design trade-off, not an inventive step.

In the applicant's favor (potential teaching away): my search surfaced JPS62255071A (Matsushita, 1986), "Refrigeration cycle using non-azeotropic mixed refrigerant." Its stated object is "to achieve uniform frost formation on the evaporator" in a non-azeotropic cycle, and its solution is to direct air from the high-temperature evaporator outlet toward the low-temperature inlet under the reasoning that "moisture in the air frosts partly from the high-temperature evaporator outlet, and air with reduced moisture content frosts sequentially on the lower-temperature evaporator inlet side." That is effectively a counterflow teaching for the very problem the patent addresses — the opposite of claim 1's parallel-flow requirement in the heating mode.

My assessment: JPS62255071A is a plausible teaching-away argument for E6 only, and it is not in the patent's citation list, so an examiner may not have considered it. It does not reach the combination of E5 (fixed resistance asymmetry) + E7 (enthalpy split), and it does not address a two-unit coil with unequal flow-path resistance. Its force is also limited because the applicant's E6 does not claim that parallel flow is better in heating — only that the direction is defined so as to be parallel in heating; the reference's concern is a single, undivided evaporator, whereas the patent's premise is that the upstream unit already runs warmer. On balance I would expect a rejection to survive a teaching-away argument here, but the argument is real and worth pre-empting.

3.5 Element E7 ("enthalpy split") — the weak link

No verified reference discloses or suggests that the upstream unit's enthalpy change exceeds the downstream unit's, and the specification does not describe it. A rejection resting on inherency would require the examiner to show the recited relationship necessarily results from the claimed geometry across the full claim scope — a showing the record does not currently contain. Two paths for the examiner:

1. Inherency/obvious-consequence: in a series evaporator, the unit with the larger pressure drop and lower tube count operates at higher refrigerant-side velocity and lower quality, so the bulk of the evaporating duty (enthalpy rise) falls in it. If that is correct, E7 is an inherent property of the structure and adds no patentable weight (In re … "inherent disclosure" line; MPEP 2111.04).
2. Supplementary art: any reference showing unequal refrigerant-side duty distribution among series-connected evaporator coil sections of an outdoor unit (several of the listed JP heat-exchanger references — JP 2012-052676 A, JP 2009-257740 A, JP H11-304292 A, JP 2012-145302 A, JP 4922669 B2, JP H09-145076 A — are candidates on their titles alone, which is all I can responsibly assert) would supply it directly.

I would not represent E7 as clearly obvious on the verified record. It is the element on which a validity challenge would most likely turn.

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4. Ground 2 (alternative): US 11,175,080 B2 as primary, in view of WO2015/151289

The roles can be inverted, and this framing better captures the purpose of the invention:

• US 11,175,080 B2 / US 2019/0277549 A1 supplies: non-azeotropic mixture (E1); an outdoor HX split into units 5a/5b (E2); single outdoor fan (E3); series connection during evaporation (E4); flow-path-number selection that changes the units' relative inlet–outlet ΔT (E5); and the express objective of suppressing partial frost by reducing the evaporator inlet–outlet temperature difference.
• WO2015/151289 supplies: the two-unit source-side coil with per-unit flow regulation and different numbers of parallel branch pipes (E5), plus the explicit statement that the working fluid may be a zeotropic/non-azeotropic blend such as R-407C (E1).
• JPH07190571A reinforces that non-azeotropic mixtures present the operative frost problem (E1 and motivation).

Motivation: the same as Ground 1, but stronger on the "problem actually recognized" axis — US 11,175,080 explicitly states the frost-suppression purpose, so the combination is not a hindsight reconstruction of the applicant's problem statement.

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5. Dependent claims

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6. Anticipated applicant rebuttals, and responses

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7. Bottom line

Claim 1 — high risk of invalidity under § 103. Elements E1–E5 are each disclosed or squarely suggested by the verified art (WO2015/151289 / US 10,161,652 B2 / US 2017/0108249 A1, plus JPH07190571A and US 11,175,080 B2). Element E6 is a conventional binary design choice, at least partly inherent in a reversing cycle, supported by an explicit KSR "known technique / predictable result" rationale — subject to a possible teaching-away argument from the 1986 non-azeotropic frost reference (JPS62255071A). Element E7 is the decision point, and it is the only element I cannot show to be obvious on the verified record.

Claims 2, 3, 4, 5, 6, 7 — high risk of invalidity. Each adds either numerical optimization of a result-effective variable, a structural implementation already suggested in PTL 1, or an inherent consequence of the reversing architecture.

Claim 8 — moderate risk. Depends on unverified secondary art for the valved hot-gas/auxiliary-exchanger circuit; this is the claim most likely to withstand challenge absent additional references.

Grounds I would assert, in order of strength:

1. US 11,175,080 B2 (or its publication US 2019/0277549 A1) + WO2015/151289 A1 + JPH07190571A, for claims 1–6.
2. Any of the above + a heat-exchanger-construction reference from the citation list (JP 2012-052676 A / JP 4922669 B2 / JP H09-145076 A) for claims 3 and 4.
3. + a three-coil series/parallel reference for claim 7.
4. + US 2015/0107286 A1 / JP 2007-155192 A / CN 201335568 Y / JP 2004-347135 (as acknowledged in US 10,161,652 B2) for claim 8.

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8. Confidence and open items

High confidence: the bibliographic record; the text of claim 1 and the dependent claims; the disclosures of US 10,161,652 B2 / US 2017/0108249 A1 and US 11,175,080 B2 / US 2019/0277549 A1 (retrieved this session); the patent's own admissions about PTL 1 and about the non-azeotropic glide-frost mechanism.

Explicitly uncertain / not verified:

• The substantive disclosures of the Tier-2 references (JPH07190571A, JPH1068560A, JPH11304292A, JP2007155192A, JP2012052676A, JP2009257740A, JP2012145302A, JP4922669B2, JP5213372B2, JP4874223B2, JPH09145076A, US20150276280A1, US20150107286A1, CN201335568Y, and the remaining citations). I have asserted only what their titles/dates/assignees support.
• Whether JPH07190571A actually discloses an air-direction/parallel-flow teaching (I inferred this only by analogy to JPS62255071A, which is a different, uncited document).
• The inherency of element E7 — the specification does not quantify the relative enthalpy changes, and I cannot confirm that the 2-tube/4-tube embodiment necessarily satisfies Δh(second) > Δh(third) across the claim's scope.
• Date-qualification flags: US 2020/0173696 A1 (Midea, priority 2018-10-22) appears to be post-critical-date and therefore not § 102 prior art; US 2017/0002245 A1, US 2019/0277549 A1, US 2019/0234643 A1 and US 2021/0108840 A1 rely on § 102(a)(2) rather than § 102(a)(1). These qualifications should be confirmed against each document's actual effective filing date before any rejection is served.

If it would help, I can (a) attempt to retrieve and verify the Tier-2 references one at a time so the claim chart can be filled to the paragraph level, or (b) draft the § 103 rejection in USPTO Office Action format (statement of the rejection + claim-by-claim chart + motivation paragraph) for either ground.