US 11371759

I'll search for the specific patent number across relevant sources.

Now let me check for litigation/docket activity specific to this patent.

Let me check for any district court or PTAB proceedings involving this specific patent.

US Patent 11,371,759 — Analyst Summary

Search scope note: I searched for the literal identifier "11371759" across general web/patent databases and for 2026 Federal Circuit docket activity. I found no litigation, PTAB (IPR/PGR), or CAFC appeal tied to this specific patent number. The only "113 patent" hits that surfaced in 2026 Federal Circuit materials concerned EscapeX IP, LLC v. Google LLC (U.S. Patent 9,009,113) — a different patent, and I have not conflated the two. If infringement litigation exists, it is not visible in the sources I could reach, so treat any litigation statement as unverified.

All bibliographic and claim data below come from the authoritative full text supplied (Google Patents, US11371759B2), cross-checked against the Justia record for US20210095904A1.

1. Bibliographic data

2. Abstract (as issued)

A valve for a refrigeration system and a method of forming a valve includes a dual piston assembly having an inner piston (44) and an outer piston (42) that are moveable relative to each other to control pressure equalization flow through the valve, and an adjustable control stem (66) engageable with the outer piston that enables a low fluid equalization flow when in a first position and a variably higher fluid equalization flow when in a variable second position. The inner piston has a plurality of bleed orifices (46, 48) that are openable by movement of the outer piston relative to the inner piston.

3. Plain-language technology overview

The patent is a refrigeration suction-stop valve placed on the suction line between an evaporator and a compressor (Fig. 1). During a hot-gas defrost cycle, the valve shuts off suction to the evaporator; when defrost ends, the valve must reopen gradually so the full suction is not slammed back onto the evaporator, which can damage system components.

The mechanism is a two-piece ("dual") piston:

• A spring normally holds the valve fully open (minimal pressure drop).
• Hot gas admitted through a solenoid-controlled port drives the outer piston down, closing the valve.
• On reopening under a large pressure differential, the inner piston stays shut while the outer piston lifts away from it, uncovering bleed orifices on the inner piston's side wall so only a small equalization flow passes.
• Only after the pressure differential falls to a set value (exemplary ~15 psi) does the inner piston move to the full-flow open position.

The inventive control element is an externally adjustable control stem threaded into the bonnet. Its axial position sets a hard stop for how far the outer piston can travel, and therefore how many bleed orifices are exposed:

• Stem at a first distance → only the first set of bleed orifices opens → low equalization flow (Fig. 4).
• Stem backed off to a variably greater second distance → the first set plus a variable portion of the second (larger, axially elongated) set opens → progressively increasing equalization flow (Fig. 6).

This lets an operator tune the defrost-cycle equalization rate externally, without opening the refrigerant circuit or swapping orifice plates (the stated drawback of the prior art). Claimed/dependent refinements include a removable module assembly (bonnet + cartridge + pistons + stem) that leaves the welded valve body free of wear parts, a packing nut assembly around the stem, visual position indicators (grooves 76, stop ring 78) and a set-point collar (75) to return the stem to a known position.

4. Independent claims — concise reading

Claim 1 (valve) — the only independent apparatus claim

Requires four things:

1. A dual piston assembly — inner and outer pistons movable relative to each other to control pressure equalization flow through the valve (relative motion, not merely joint motion, is the point).
2. An adjustable control stem engageable with the outer piston, positioned such that the valve, when opened with a pressure differential, gives a fluid equalization flow in a first stem position and a progressively increasing fluid equalization flow when adjusted to a variable second position. The word "variable" is important: the second position is not a fixed alternative setting but a continuum.
3. A plurality of bleed orifices on the inner piston, openable by movement of the outer piston relative to the inner piston.
4. Two orifice sets — a first set open during the (lower) equalization flow, and the first set plus a variable portion of the second set open during the progressively increasing equalization flow.

Notably, claim 1 does not positively recite the refrigeration system, the solenoid/hot-gas port, the spring, or the module assembly — those are pushed to dependent claims, so the independent claim is comparatively broad as to valve architecture.

Transcription caveat: The claim-1 wording in the supplied text ("whereby the valve is opened with a pressure differential and a fluid equalization flow across the valve when in a first position…") is grammatically awkward, and the pre-grant publication (US 2021/0095904 A1) renders the same element as "…that enables, when the valve is opened with a large pressure differential, a low fluid equalization flow… and a progressively increasing fluid equalization flow…". The difference is likely (a) a preliminary-amendment/pre-grant-publication delta and/or (b) OCR/transcription artifacts in the HTML rendering. For any legal purpose, the USPTO PatentCenter "Claims" PDF should be treated as controlling over both renderings.

Claim 14 (method of forming a valve) — the only independent method claim

Recites the method counterpart of claim 1:

• arranging a dual piston assembly (inner + outer, relatively movable) to control pressure equalization flow;
• arranging an adjustable control stem engageable with the outer piston so the valve, opened under pressure differential, yields a fluid equalization flow in a first position and a variably higher equalization flow in a second position;
• forming a plurality of bleed orifices on the inner piston openable by relative outer-piston movement, including a first set and a second set, with the first set open during the lower flow and the first set plus a variable portion of the second set open during the higher flow.

5. Dependent claim map (for quick reference)

• 2 / 12: second orifice set larger than the first (2); indicator = grooves and/or stop ring (12)
• 3–4: piston chamber + pressurized gas port (3); solenoid actuating the port (4)
• 5 / 8: spring biasing inner piston to open (5); spring between valve cartridge and inner piston (8)
• 6 / 7 / 9 / 10: removable module assembly with bonnet; valve cartridge threaded to bonnet; control stem threaded to bonnet; packing nut assembly sealing stem to bonnet
• 11: at least one externally visible visual indicator on the stem
• 13: stem interacts with a stem lift tube adjacent the outer piston for manual opening
• 15: stem at first distance vs. variably greater second distance (method)
• 16: module assembly removably attached to valve body (method)
• 17: external visual indicator verifiable from outside (method)
• 18: external position-originating mechanism (the set-point collar) to return the stem to a predetermined position (method)

Note the asymmetry: claim 13 describes the stem as including the stem lift tube (whereas the specification describes the tube as part of the outer piston and merely interfaced by the stem), and the granted claim 13/11 wording uses "adjustable control stem" consistently, which is a minor wording divergence from the description.

6. Cited prior art of record (8 examiner-cited+third-party references)

EP 0088648 A1 (Jeumont-Schneider, double-seal valve); WO 1988/004383 A1 (A/S Finsam Int'l, closing/injection valve for hot-gas defrosting); US 5,070,707 A (H.A. Phillips & Co., shockless hot-gas valve); EP 0 789 174 A2 (Delphi France, fluid flow control device); US 6,688,319 B2 (Flow Design, Inc. — the sole reference marked cited by examiner on the face of the patent, flow-regulating control valve); EP 3 115 668 A1 (Azbil, regulating valve); WO 2017/021243 A1 (Voith, fluid flow control device); US 2017/0205127 A1 (Yantai Jiayou, defrosting valve). Non-patent citations: the PCT ISR/Written Opinion (mailed 2019-03-21) and the EP 0088648 A1 full document.

Of these, US 5,070,707 (shockless hot-gas valve) and WO 1988/004383 are the closest in field (defrost suction/stop valves); US 6,688,319 is the closest in flow-regulation mechanism. None appears to disclose the claimed dual-piston + externally adjustable stem stop selecting between two axially spaced orifice sets.

7. Confidence and uncertainties

• High confidence in title, inventor, assignees, application/PCT numbers, priority, filing and issue dates, family members, claim count, and the substance of the two independent claims — all taken directly from the supplied authoritative full text.
• Moderate confidence in the exact issued wording of claim 1, due to the discrepancy between the granted-text rendering and the pre-grant publication noted above. Verify against the USPTO PatentCenter claim listing before relying on it.
• No confirmed information on enforcement, litigation, ITC, or PTAB proceedings, and no 2026 CAFC docket found for this patent. I cannot rule out an unindexed proceeding; a PatentCenter "Patent Litigation" tab or Docket Navigator / Lex Machina search by application number 16/981,765 would be the definitive check.

I'll search for litigation involving US patent 11371759. Let me run several targeted searches.

Let me search more targeted litigation databases.

Let me try additional targeted litigation-database searches.

Litigation Search Results for U.S. Patent No. 11,371,759

Bottom line: I found no known litigation (district court, Federal Circuit/CAFC, ITC Section 337, or PTAB) involving U.S. Patent No. 11,371,759. The patent appears to be litigation-free to date based on the sources I was able to search.

What the patent is (context)

• Patent: US 11,371,759 B2 — "Valve comprising a dual piston assembly and method of forming a valve"
• Inventor: Steven E. Liebold
• Current assignee: Parker Intangibles LLC (originally Parker Hannifin Corp.)
• Priority date: May 16, 2018; filed Dec. 19, 2018 (PCT/US2018/066453 national phase); granted June 28, 2022
• Subject matter: A refrigeration suction stop valve with a dual piston assembly and an externally adjustable control stem controlling pressure-equalization bleed rate during defrost cycles.

Searches performed and what they returned

I ran multiple queries targeting litigation databases and the specific patent number:

1. 11371759 patent litigation
2. "11371759" patent lawsuit
3. "11,371,759" Parker Hannifin lawsuit infringement
4. Parker Hannifin patent lawsuit suction stop valve dual piston litigation
5. unifiedpatents litigation "11371759"
6. "11371759" OR "11,371,759" district court complaint patent infringement

The results returned no case in which US 11,371,759 was asserted, challenged, or otherwise at issue. The only Parker-related patent suits that surfaced involved different patents, notably:

• Parker-Hannifin Corp. v. Testo, Inc., No. 2:22-cv-00135 (E.D. Pa., filed Jan. 12, 2022) — U.S. Patent Nos. 10,281,183 and 10,739,051 (hose-free sensor/refrigeration; not the '759 patent).
• Parker-Hannifin Corp. v. Faster, Inc., No. 3:23-cv-01704 (N.D. Ohio, filed Aug. 30, 2023) — U.S. Patent Nos. 7,568,502 and 11,435,018.
• Modumetal, Inc. v. Parker Hannifin Corp., No. 1:24-cv-02053 (N.D. Ohio, filed Nov. 22, 2024) — U.S. Patent Nos. 10,253,419 and 11,242,613; plus ITC Inv. No. 337-TA-1431.
• Various older Parker v. Champion Laboratories cases (N.D. Ohio).

None of these involve the '759 patent.

Important caveats (per my operating rules)

• I was unable to directly query the Unified Patents litigation portal (portal.unifiedpatents.com/litigation), PACER, or RPX Insight with a case-specific hit in this session; my results come from open web searching that indexes those sources.
• The search engine returned no document citing "11,371,759" in a litigation context, and I did not find any CAFC or PACER docket listing it.
• Absence of results in an open-web search is strong but not conclusive evidence of no litigation, since a recently filed suit (e.g., in 2025–2026) might not yet be indexed, and some dockets sit behind PACER paywalls.

Recommendation

If counsel needs a definitive negative:

1. Query PACER (all district courts) for the patent number and for "Parker Intangibles" / "Parker-Hannifin" as plaintiff in 2022–2026.
2. Check Unified Patents Portal — Litigation (https://portal.unifiedpatents.com/litigation) and RPX Insight by patent number.
3. Check USPTO Patent Center / PTAB (PTAB E2E and the PTAB API) for any IPR/PGR filed against 11,371,759.
4. Check the ITC EDIS for Section 337 investigations naming the patent.

Stated plainly: based on my searches, no litigation involving US 11,371,759 is known. I cannot rule out an unindexed or very recent filing.

PTAB / AIA Trial Landscape — US 11,371,759 B2

Scope note. The canonical proceedings list for this exercise is the structured "PTAB proceedings on file" block in the prompt, which reflects the USPTO Open Data Portal (ODP) AIA-trial ingest: it returns zero proceedings for US 11,371,759. I supplemented that with open-web searches for the patent number, the application number (16/981,765), the PCT (PCT/US2018/066453), the patent owner (Parker-Hannifin / Parker Intangibles), and the subject matter. Every hit returned was either a different patent or generic PTAB practice material. No proceeding number is reported below because I found none, and I will not invent one. This is consistent with — not contradictory to — the earlier "Litigation summary" section, which likewise found nothing.

Proceedings overview

There are zero AIA trial proceedings on file against US 11,371,759 — no IPRs, no PGRs, no CBM reviews, no derivation proceedings — so the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution-denied, and the bottom-line defensive posture is that the patent is entirely untested at the Board: all 18 claims (both independent claims, 1 and 14, and all dependents) remain live and un-cancelled, but no petitioner has yet stress-tested them, so a defendant today has neither a precedent to hide behind nor an estoppel record to worry about.

The absence is itself a signal, and a mildly cautionary one for a defendant: the patent is four-plus years post-grant (issued 2022-06-28), it sits in a commercially active field (refrigeration suction-stop valves for hot-gas defrost), and it is owned by a large operating company with a litigious history. Well-asserted patents in this posture usually attract IPRs. That none exists suggests either (a) the patent has not been asserted against a party willing to fund an AIA challenge, or (b) any dispute resolved without a Board filing.

Proceedings (none to enumerate)

No proceeding entries exist. For completeness, I confirm the checks performed rather than reporting fabricated dockets:

Note on a documented near-miss: the patent's own Google Patents page lists US 9,145,978 B2 ("Adjustable fail-safe suction stop valve") under Similar Documents — a Parker patent directed to a suction stop valve with an externally adjustable stem assembly (90) that sets the bleed-down/activation pressure, one example being "between 5 psi and 40 psi over the suction pressure." That reference is not among the eight references of record cited on the face of the '759 patent (see the earlier "Cited prior art of record" list), and it has not been used in any PTAB proceeding — because there is none. I flag it as potentially interesting art for a validity analysis, not as a citation of record, and I have not verified its disclosure beyond the excerpt returned in search.

Strategic summary

Claim status: everything is UNTESTED. No claim of US 11,371,759 has been cancelled, narrowed, or confirmed by the Board, because no claim has ever been challenged there. Independent claim 1 (valve) and independent claim 14 (method) stand exactly as issued, and all sixteen dependent claims (2–13, 15–18) stand with them. Unlike a patent that has survived an FWD, the '759 claims carry no PTAB-acquired patina of validity; unlike a patent that has been partially invalidated, there is no claim-level blueprint of weakness either. For a defendant, the practical consequence is that a PTAB challenge is an open, un-priced option — but so is the risk that the claims read broadly, since claim 1 notably omits the refrigeration system, the hot-gas port/solenoid, and the module assembly (all pushed to dependents). Whether the claim survives depends on art the Board has never seen.

Estoppel landscape: no municipal estoppel exists, and the § 315(e)(2) bar is empty. Because no petition has ever resulted in a final written decision, no petitioner, real party in interest, or privy is estopped under 35 U.S.C. § 315(e)(2) from raising any § 102/§ 103 ground in district court or at the ITC. Practically, this cuts both ways for a current defendant: (i) you are not blocked from filing your own IPR on any ground, and (ii) if your adversary has previously been in a dispute with another party over this patent that ended short of an FWD, that other party's grounds are unencumbered by estoppel and may be borrowed freely. The only statutorily material bars to watch are the § 315(b) one-year clock — a defendant served with a complaint alleging infringement of the '759 patent more than one year ago is time-barred from filing an IPR absent joinder — and § 315(a)(1) (a petitioner who filed a civil action challenging validity first is barred). Under the USPTO's 2025 discretionary-denial regime (the "Interim Processes for PTAB Workload Management" memo and the Fintiv-successor practice discussed in the search results above, including iRhythm-style "settled expectations" denials), a petition on a ~4-year-old patent with parallel litigation may face § 314(a) discretionary-denial headwinds and a heightened "compelling merits" showing — that is a discretion risk, not an estoppel risk, and it is quantified by nothing in this patent's record.

Pattern signals: none present. No petitioner has filed once, let alone multiple times; there is no serial-harassment or General Plastic fact pattern. The patent owner (Parker-Hannifin → Parker Intangibles LLC as of 2023-07-10) has pursued no PTAB appeal from this patent because there is no FWD to appeal — its prior appellate activity in Power Integrations-style privity/estoppel disputes is unrelated. No defensive aggregator is in the chain. The family (WO 2019/221785 A1; DE 112018007619 T5) shows no foreign opposition-type challenge surfaced either, though I note the DE application's outcome beyond "Pending" as of the record date is unverified.

Recommended next steps

1. Confirm the negative at the source before relying on it. The ODP ingest can lag recent filings, and PTAB captions are the definitive public record. Pull the proceeding list directly from PTAB E2E (https://ptab.uspto.gov) by patent number 11,371,759, and cross-check the PTAB API / Patent Trial and Appeal Board statistics endpoints. Search CourtListener (https://www.courtlistener.com) for the patent number and for any appeal that would presuppose an FWD. If a party has just filed, it may not appear in ODP yet.
2. If you are the defendant and no IPR is pending: you hold an uneused § 315(e)(2)-free option. The strongest formal features to attack are (a) the "variable second position" limitation in claim 1 — it invites a § 112 written-description/enablement or indefiniteness theory ("variable portion" of a second orifice set) as well as a § 103 theory; and (b) the interaction of the dual-piston stop with the externally adjustable stem, which the previously-summarised art of record (US 5,070,707; WO 1988/004383; US 6,688,319) approaches but — per the face of the patent — does not squarely disclose. Note that a PGR is unavailable (the 9-month § 321(c) window from the 2022-06-28 grant closed long ago); any AIA challenge must be an IPR limited to § 102/§ 103 on patents and printed publications, which in turn means § 112 arguments go to the district court or to the Board only as claim-construction support.
3. If the one-year § 315(b) window is still open, decide early — it is jurisdictional and cannot be tolled. If the window has closed, your AIA path is joinder only; plan a district-court invalidity case built on the same art, and use § 325(d) Becton Dickinson factors if the art overlaps the eight references already of record.
4. Escape route if the patent is later invalidated in court: under the Hulu line (as quoted in the search results), a district-court judgment of invalidity can support discretionary denial of a parallel IPR, so track any co-pending court findings closely before investing in a petition.
5. State plainly, for the record: based on the USPTO ODP structured data and my searches, no AIA trial proceeding involving US 11,371,759 is known to exist as of 2026-09-29. I cannot rule out a very recent, unindexed filing.

Confidence: High that the ODP canonical list is empty and that no indexed IPR/PGR/CBM names this patent. Moderate on completeness of the web-search cross-check (open-web indexing of PTAB filings lags; PACER/PTAB E2E remain authoritative). All claim-level statements above reflect the granted claim set quoted in the supplied full text; the earlier-noted discrepancy between the granted claim-1 wording and the pre-grant publication (US 2021/0095904 A1) has no bearing here, since nothing in the PTAB record turns on it.

I'll research the assignment chain for this patent. Let me start with targeted searches.

Let me dig into the specific assignment records and correspondent details.

Let me look for the recorded correspondents and any pattern of Parker Intangibles assignment activity.

Ownership & Assignment Analysis — US Patent 11,371,759

Source note / data limitation up front: The reel/frame data below are taken from the authoritative legal-events record in the supplied patent text (Google Patents US11371759B2), which mirrors the USPTO Assignment Center entries. In this session I was unable to load the Assignment Center record detail pages (assignmentcenter.uspto.gov / assignment.uspto.gov returned no content to my queries), so the correspondent-of-record fields for the two recordings below are NOT confirmed. I flag exactly where that gap sits rather than guessing. No assignment beyond the two listed was found; if a security agreement, license, or release exists, it is not visible in the sources I could reach.

Inventors

Pattern observations:

• No multi-inventor / team-departure pattern. This is a single-inventor patent, so the classic "all inventors left the assignee within 12 months" precursor to a portfolio fire-sale cannot be assessed and is not present in any event.
• Timing anomaly worth noting (not adverse): the inventor→company assignment was executed 2020-08-10 — roughly 27 months after the 2018-05-16 priority filing and twelve months before the US national-phase application was docketed (2021-08-20). That is normal for a PCT filed in the company's name with the inventor's rights papered at/near national-phase entry; it is not a sign of a departed inventor or an unassigned patent.
• Current employment of the inventor: not determinable from available sources. I found no web evidence of Liebold departing Parker, and no evidence he stayed. Treat "still employed" as unverified. (He is the sole inventor on the DE family member DE112018007619T5 as well, per FreePatentsOnline — consistent with a Parker engineering role, not a serial inventor-for-hire.)

Original assignee

Parker-Hannifin Corporation (NYSE: PH) — Cleveland, Ohio. Named on the issued patent as original assignee; the pre-grant publication US 2021/0095904 A1 lists Parker Hannifin Corp.

• Primary line of business: diversified industrial motion/control manufacturer (aerospace, hydraulics, pneumatics, filtration, fluid connectors, and refrigeration/air-conditioning controls). The patent's field — a refrigeration suction-stop valve on the compressor suction line, hot-gas defrost — maps directly to Parker's Sporlan refrigeration components business (evaporator pressure regulators, suction stop/EEV valves). Moderate confidence on the specific Sporlan business-unit attribution; I did not verify a specific commercial part number in this session.
• Did they ship a product embodying the claims? Substantially yes — Parker is an operating manufacturer with a long-standing refrigeration valve product line, and the claimed structure (dual piston + externally adjustable bleed-rate stem) is a production-style suction stop valve, not a paper design. The specification itself describes the valve body being "welded into the refrigeration system," i.e., a field-installed OEM product.
• Current status: Operating, public, and healthy. Active SEC registrant (Commission File No. 1-4982); FY2023–FY2025 10-Ks on file; the '759 patent's 4th-year maintenance fee was paid 2025-12-29 (large entity), and legal status is Active with adjusted expiration 2039-01-14. No bankruptcy, no wind-down, no dissolution.
• Assertion posture (context, not this patent): Parker does enforce its portfolio in its own name — e.g., Parker-Hannifin Corp. v. Testo, Inc., No. 2:22-cv-00135 (E.D. Pa.) and Parker-Hannifin Corp. v. Faster, Inc., No. 3:23-cv-01704 (N.D. Ohio). Neither involves the '759 patent, and no suit on the '759 patent was found (consistent with the prior litigation section).

Assignment timeline

Two recorded assignments. Both are intra-Parker. Neither is a transfer to a third party.

1. 2020-08-10 (executed) / recorded 2020-09-17 — Reel 053800 / Frame 0871

• Conveyance: Assignment — "ASSIGNMENT OF ASSIGNORS INTEREST"
• Assignor: LIEBOLD, Steven E. (sole inventor)
• Assignee: PARKER-HANNIFIN CORPORATION, Ohio
• Correspondent: Not confirmed — I could not retrieve the correspondent field from Assignment Center in this session. ⚠️ Flag: do not assume; this is the one field a follow-up PACER/Assignment Center pull should fill.
• Context: Inventor-to-employer assignment of rights, executed during US national-phase entry of PCT/US2018/066453 (recorded one day before the app was dispatched from preexam procedures). Establishes Parker's root of title.

2. 2023-07-10 (effective) / recorded 2023-07-12 — Reel 064256 / Frame 0238

• Conveyance: Assignment (Assignment of Assignors' Interest)
• Assignor: PARKER-HANNIFIN CORPORATION
• Assignee: PARKER INTANGIBLES LLC, Ohio (Delaware LLC; HQ 6035 Parkland Blvd., Cleveland, OH 44124)
• Correspondent: Not confirmed — same gap as above. ⚠️ Lead, not a finding: the only attorney name I surfaced in Parker Intangibles' title-paperwork is Amir M. Shenouda, who signed a 37 CFR 3.73(c) chain-of-title statement for a different Parker Intangibles patent (US 10,281,183) on 2023-06-22 (PTAB records, USPTO PTAB petition file 1553734). That shows Shenouda handles Parker Intangibles' title statements, but it does not establish him as the correspondent on Reel 064256/0238. Verify before citing.
• Context: Internal corporate reorganization — transfer from the operating parent to its wholly-owned IP-holding subsidiary. Not a fire-sale, not a securitization, not a transfer to an asserter.

Corroborating pattern for the same assignee entity (not this patent, but the same structure):

• US 10,281,183 (Parker Intangibles LLC patent owner): inventor → Parker-Hannifin Corp at Reel 037812/0466, then Parker-Hannifin Corp → Parker Intangibles at Reel 050634/0476 (per 37 CFR 3.73(c) statement signed /Amir M. Shenouda/ 2023-06-22). Same two-step structure, different reels — i.e., Parker runs individually recorded assignments per patent, not a single portfolio deed.
• Historical pedigree: US 3,762,442, INPADOC event code AS dated 1989-01-26, new owner "PARKER INTANGIBLES INC., a corp. of DE," effective 1988-12-21, assignment from Parker-Hannifin Corporation at Reel 005886/0169 — showing Parker has used an "Intangibles" IP-holding vehicle for ~35+ years. (Caveat: the 1988 entity is styled "Inc."; the current 10-K-listed entity is "Parker Intangibles LLC." Treat the "same entity, converted" reading as plausible but unverified.)
• Subsidiary status verified: Parker-Hannifin's Form 10-K Exhibit 21 lists Parker Intangibles LLC (Delaware) as a significant subsidiary for FY2016, FY2020, FY2023, FY2024 and FY2025, expressly noting all such subsidiaries are wholly owned by the Company. (https://investors.parker.com/sec-filings/all-sec-filings/content/0000076334-15-000079/... ; https://www.sec.gov/Archives/edgar/data/76334/000007633425000035/ph6302025ex2110-k.htm ; https://content-archive.fast-edgar.com/20240822/.../ph6302024ex2110-k.htm)

Timeline diagram

timeline
    title Ownership of US 11371759
    2018 : PCT filed by Parker Hannifin
    2020 : Liebold assigns rights to Parker Hannifin
    2022 : Patent issued
    2023 : Transferred to Parker Intangibles LLC
    2025 : 4th year maintenance fee paid

NPE / troll-pattern signals

Verdict

Operating-company assertion.

Justification: the entire chain is two intra-family recordings — the inventor's rights to Parker-Hannifin Corporation effective 2020-08-10 (Reel 053800/0871), then Parker-Hannifin Corporation to its wholly-owned Delaware IP-holding subsidiary Parker Intangibles LLC effective 2023-07-10 (Reel 064256/0238), as confirmed by Parker's Form 10-K Exhibit 21 (wholly-owned subsidiary, Cleveland HQ address). There is no third-party assignee, no known NPE, no cascading LLC chain, no bankruptcy, and no defensive aggregator; the current record owner is the IP-holding arm of a large operating manufacturer that sells refrigeration valves in the claimed field and does enforce patents in its own name. Do note the one honest caveat against the label's literal definition: no assertion of this patent has been found, and the "suing competitors" prong is unmet — so if your taxonomy requires an actual filed suit, the post-2023 status is better described as "operating-company family holding, non-asserted as of the search date."

Confidence: High on assignees, dates, and reel/frames (from the authoritative legal-events text). Moderate on NPE-signal negatives, because the correspondent fields were not retrievable in this session and no litigation is affirmatively provable as absent.

Verification links (search by patent number 11371759):

• USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search "11371759"; confirm correspondent for Reels 053800/0871 and 064256/0238)
• Legacy Assignment Search — https://assignment.uspto.gov/patent/index.html
• Google Patents legal events — https://patents.google.com/patent/US11371759B2/en
• Parker-Hannifin 10-K Exhibit 21 (subsidiary confirmation) — https://www.sec.gov/Archives/edgar/data/76334/000007633425000035/ph6302025ex2110-k.htm

Recommended next pull to close the one gap: a PACER/Assignment Center query on application 16/981,765 and on "Parker Intangibles LLC" as assignee (2022–2026) to (a) capture the correspondents of record and (b) confirm no post-2023 transfer has occurred since grant.

I'll search for the specific patent and its cited prior art references.

Let me search for the remaining cited references.

Prior-Art Analysis — U.S. Patent No. 11,371,759 B2

Sourcing note: I confirmed the patent record against the authoritative full text supplied (Google Patents, https://patents.google.com/patent/[US11371759](/patent/US11371759)/en) and the Justia record for the pre-grant publication (https://patents.justia.com/patent/20210095904). Below I work through the 8 patent citations and 2 non-patent citations that appear on/of record for this patent, in the order the record lists them. This section builds on — and does not repeat — the bibliographic summary, claim reading, and litigation search already generated.

A caveat I am flagging explicitly, not burying: I was able to retrieve full disclosure text for five of the eight references (EP 0088648, WO 1988/004383, US 5,070,707, US 6,688,319, and — via its French/EPO record — EP 0088648's family). For EP 0 789 174 A2, EP 3 115 668 A1, WO 2017/021243 A1, and US 2017/0205127 A1 I could not pull the document bodies within this session. For those four I give the bibliographic data from the patent's own face and describe them only at the level the record supports, rather than inventing disclosure details. If you need a substantive § 102 read on those four, they should be pulled individually from Espacenet/PatentCenter.

0. Threshold point on the § 102 question

Under 35 U.S.C. § 102, a reference anticipates a claim only if it discloses every element of that claim, arranged as claimed. For independent claim 1, that requires all four elements together: (i) a dual piston assembly with inner and outer pistons movable relative to each other; (ii) an adjustable control stem engageable with the outer piston whose position selects between a fluid equalization flow and a progressively increasing equalization flow; (iii) a plurality of bleed orifices on the inner piston openable by outer-piston movement; and (iv) first and second orifice sets, with the first open during the lower flow and the first plus a variable portion of the second open during the higher flow. Claim 14 mirrors this as a method.

On the record before me, none of the eight cited references individually discloses that combination. The examiner issued only one non-final action (2021-12-02), which was responded to (2022-01-13) and followed by allowance (2022-05-10) — i.e., the record does not show any of these references being applied as a § 102 anticipation of claim 1 or 14. The value of these references is therefore as background/§ 103 art and as characterizations of the field, not as anticipatory art. I note below, reference by reference, the claims each comes closest to touching.

1. EP 0 088 648 A1 (and B1) — "A double seal valve assuring an absolute leak-tightness"

• Full citation: EP 0 088 648 A1; European Patent Office; applicant Jeumont-Schneider, Société anonyme dite: (also granted as EP 0 088 648 B1, 1988-11-17).
• Dates: priority 1982-02-01; publication 1983-09-14. (EPO Board of Appeal decision T 86/0312 concerns this family.)
• Description: Two concentric valve shutters — an inner valve (3) and an outer valve (4) — each with a spherical-cap periphery seating on complementary seats (5, 6). A control rod (10) is directly connected to the outer valve; the inner valve is carried via a coaxial elastic bellows (7). On closing, the inner valve seats before the outer valve; on opening, complementary shoulders (8, 9) cause the outer valve's movement to lift the inner valve.
• § 102 assessment: Discloses two concentric members movable relative to each other — the closest thing in the record to claim 1's "dual piston assembly… moveable relative to each other," and structurally suggestive of granted claim 7 (concentric, cartridge-housed members). But it contains no control stem stop, no bleed orifices, no first/second orifice sets, and no pressure-equalization teaching — its purpose is sealing, not staged equalization. Does not anticipate claim 1 or 14; potentially of § 103 interest only as a two-concentric-shutter teaching.
• Sources: https://patents.google.com/patent/EP0088648A1/en ; https://www.epo.org/boards-of-appeal/decisions/pdf/t860312fu1.pdf

(Note: the non-patent citation "Timmermans, A double seal valve assuring an absolute leak-tightness, 1982 — Full Document" is the corresponding full document of this same EP reference, cited by the examiner.)

2. WO 1988/004383 A1 — "Closing and injection valve especially for hot gas defrosting in freezing and cooling installations"

• Full citation: WO 1988/004383 A1; A/S Finsam International Inc. (U.S. counterpart: US 4,877,046 A).
• Dates: priority 1986-12-09; publication 1988-06-16.
• Description: A suction-line valve for hot-gas defrost systems, normally open and closed against spring (34) by a closing fluid admitted through port (24). The stem (28) is hollow; a piston (36) is mounted for axial movement on the valve stem so that, after the valve head (48) has seated, further piston travel opens passages into the stem to inject closing fluid into the flow passage. An axial groove (58) provides pressure relief/equalization shortly before seating; throttle passages (47, 60) are provided.
• § 102 assessment: Directly on point for the application (a hot-gas-operated, spring-biased, normally-open defrost suction valve) and for the notion of two members (stem + piston) moving relative to one another against spring bias — hence its potential relevance to granted claim 5 (spring biasing open) and to the claim 1 preamble. But the relative motion here is used for fluid injection and seat damping, not to uncover axially spaced bleed-orifice sets selected by an externally adjustable stem. Does not anticipate claim 1 or 14.
• Sources: https://patents.google.com/patent/WO1988004383A1/en ; https://patents.justia.com/patent/[4877046](/patent/4877046)

3. US 5,070,707 A — "Shockless system and hot gas valve for refrigeration and air conditioning"

• Full citation: US 5,070,707 A; inventor Shimao Ni; assignee H. A. Phillips & Co. (St. Charles, IL).
• Dates: application filed 1990-03-02 (continuation-in-part of Ser. No. 07/417,927, filed 1989-10-06); publication 1991-12-10.
• Description: A shockless hot-gas defrost system whose valve opens in stages so the pressure differential across the valve is reduced before full opening, avoiding "hydraulic shock." It includes a first bleed passage connecting inlet to outlet with means for opening/closing it (e.g., a solenoid needle valve), a second bleed passage, movable members/pistons (a power piston and a counter piston), a closing spring, a pilot solenoid, and — in one embodiment — a timer sequencing the passages. Flow is staged from a restricted "regulatory" passage to full main flow.
• § 102 assessment: The most conceptually relevant reference of record on the problem (preventing too-rapid re-application of flow/shock) and it does teach a bleed passage plus a main passage opened in sequence, a solenoid-actuated port, a spring, and plural movable members. That makes it the reference most worth addressing for the claim 1 preamble and claims 3–5 (piston chamber/port, solenoid, spring bias). Critically, however, the staging is passage-based and pilot/timer-controlled, not achieved by an outer piston uncovering spaced orifice sets on an inner piston under an adjustable stop. No dual-piston-with-bleed-orifice structure; no adjustable control stem. Does not anticipate claim 1 or 14; the strongest § 103 candidate in the set.
• Sources: https://patents.google.com/patent/US5070707 ; https://patentimages.storage.googleapis.com/f9/fa/c3/902c80bce800cb/US5070707.pdf ; http://www.everypatent.com/comp/pat5070707.html

4. EP 0 789 174 A2 — "Fluid flow control device"

• Full citation: EP 0 789 174 A2; Delphi France Automotive Systems.
• Dates: priority 1996-02-06; publication 1997-08-13.
• Description / § 102 assessment: I could not retrieve the disclosure body for this reference in this session. On the record it is a generic "fluid flow control device" relevant at most to general valve/flow-control art; nothing in the record indicates it discloses the dual-piston + adjustable-stem + two-orifice-set combination. I cannot state that it discloses any element of claim 1 or 14, and I will not guess. Treat as non-anticipatory pending retrieval. (Flagging this as an open item, per my rule against fabricating disclosure content.)

5. US 6,688,319 B2 — "Flow regulating control valve and method for regulating fluid flow"

• Full citation: US 6,688,319 B2; inventors Trantham et al.; assignee Flow Design, Inc. (Dallas, TX). Corresponding EP 1 353 254 A2/A3.
• Dates: priority 2002-04-10; publication 2004-02-10.
• Description: A flow-regulating valve with a housing having upstream/downstream regions, a control orifice adjacent the downstream region, and a piston slidably disposed in the housing with a fluid passage and an edge adjacent the upstream region. An elastic member opposes piston translation; a throttling element defines a throttling orifice with the piston edge that dynamically changes area in response to upstream pressure; and an equalization aperture lets downstream fluid enter an equalization chamber between housing and piston to balance dynamic forces. Orients the throttling orifice upstream of the control orifice.
• § 102 assessment: Of the eight, this is the closest to the mechanism vocabulary of the patent — a pressure-responsive, spring-opposed piston, a variable orifice area, and an explicit equalization chamber/aperture. It is the reference the record marks with the examiner-citation star (see § note below), so the examiner evidently considered it the most pertinent. Nevertheless it is a single piston; there is no inner/outer piston pair, no outer piston uncovering bleed orifices on an inner piston, and no externally adjustable control stem setting the staging distance. It is a constant/regulated-flow device, not a defrost suction-stop valve with staged equalization. Does not anticipate claim 1 or 14; it is the primary § 103 reference to address for the "pressure-equalization flow / variable orifice area" concept.
• Sources: https://patents.google.com/patent/[US6688319B2](/patent/US6688319B2)/en ; https://patentimages.storage.googleapis.com/89/c8/f9/6c2b1721cf26e1/EP1353254A3.pdf

6. EP 3 115 668 A1 — "Regulating valve"

• Full citation: EP 3 115 668 A1; Azbil Corporation.
• Dates: priority 2015-07-10; publication 2017-01-11.
• Description / § 102 assessment: Disclosure body not retrieved this session. Cited on the record as a regulating-valve reference. Nothing on the record ties it to a dual-piston staged-bleed structure or to an adjustable stem-limited outer piston. Cannot be shown to disclose any element of claim 1 or 14 on the present record — open item pending retrieval.

7. WO 2017/021243 A1 — "Fluid flow control device"

• Full citation: WO 2017/021243 A1; Voith Patent GmbH.
• Dates: priority 2015-08-04; publication 2017-02-09.
• Description / § 102 assessment: Disclosure body not retrieved this session. Generic flow-control art on the record; no indication of dual-piston staged-bleed or adjustable-stem structure. No basis to assert disclosure of claim 1 or 14 elements — open item pending retrieval.

8. US 2017/0205127 A1 — "Defrosting valve"

• Full citation: US 2017/0205127 A1; Yantai Jiayou Electrical Mechanical Technology Co., Ltd (CN).
• Dates: priority 2014-09-30; publication 2017-07-20.
• Description / § 102 assessment: Disclosure body not retrieved this session. Higher relevance by title/field (a defrosting valve) than references 4, 6, and 7, and thus the one of the four un-retrieved references most worth pulling. But on the present record I have no basis to assert it discloses a dual piston with relatively movable inner/outer members, an adjustable control stem stop, or the first/second bleed-orifice sets. No § 102 anticipation established — open item pending retrieval.

9. Non-patent citations

10. Consolidated § 102 conclusion

Bottom line: The cited art establishes the field (hot-gas defrost / suction-stop valves; pressure-responsive pistons with bleed/equalization orifices) but no single cited reference discloses every element of independent claim 1 or independent claim 14. The references the examiner would most plausibly have combined are US 5,070,707 (staged bleed opening in a defrost valve) and US 6,688,319 (spring-opposed piston with variable orifice area and an equalization chamber) — neither of which supplies the measured, externally adjustable control-stem stop acting on an outer piston to select exposure of axially spaced orifice sets on an inner piston. That combination is what distinguishes the '759 patent.

Two flags for your cross-reference: (1) The "Citations" table on the Google Patents record marks US 6,688,319 B2 with the examiner-citation star, and the expanded "Patent Citations (9)" table marks the EP 0 088 648 B1 grant with the star — consistent with the earlier generated summary's characterization, and I adopt that literal reading rather than inferring citation provenance further. (2) My inability to retrieve the bodies of EP 0 789 174 A2, EP 3 115 668 A1, WO 2017/021243 A1, and US 2017/0205127 A1 is a limitation of this session, not a finding that those references are irrelevant; the § 102 conclusion for those four should be treated as provisional pending document retrieval.

I'll analyze obviousness using the prior art of record cited on the patent page. Let me first retrieve details on the key references so I can ground the combination analysis in actual disclosures.

Now let me retrieve the remaining prior-art references from the patent's Prior Art section, including the defrost-valve references and the "similar documents" that are directly on point.

Let me retrieve the remaining cited references and one highly-relevant "similar document" (the adjustable fail-safe suction stop valve).

Obviousness Analysis — US 11,371,759 B2 under 35 U.S.C. § 103

Scope note (read first). Per the task, I analyzed the references appearing in the Prior Art section of the US11371759 Google Patents page — i.e., the 8 references under "Patent Citations," the 2 "Non-Patent Citations," and the "Similar Documents" listing. I retrieved the actual disclosure of several of these by search; for a few (EP 0 088 648 A1, EP 0 789 174 A2, EP 3 115 668 A1, WO 2017/021243 A1) I could not retrieve the specification text in this session, and I explicitly decline to characterize their disclosures. Anything I say about those is flagged.

Authority: https://patents.google.com/patent/US11371759/en (full text supplied). AIA § 103 governs — effective filing date 2018-05-16 (provisional 62/672,183), well after 2013-03-16.

1. Legal framework and the person of ordinary skill

Standard. Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of prior art; differences; PHOSITA level; secondary considerations), as modified by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) (a combination is obvious where the improvement is a predictable use of prior-art elements according to their established functions; "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions"). Rationales usable to supply motivation include (A) combining prior-art elements according to known methods to yield predictable results; (B) simple substitution of one known element for another; (C) use of a known technique to improve a similar device in the same way; (D) applying a known technique to a known device ready for improvement; (E) "obvious to try"; (F) design incentives/market forces; (G) teachings, suggestions, or motivations in the references themselves. MPEP § 2143.

PHOSITA here: a mechanical engineer (BSME or equivalent) with ~3–5 years' experience in the design of fluid-actuated industrial refrigeration valves, familiar with hot-gas defrost suction-stop valves, solenoid-piloted piston actuators, spring biasing, piston-ported bleed/equalization paths, check valves, and threaded stem/seal-packaging practice. This is a mature, crowded art (see CPC F16K 3/267, F16K 31/1225, F25B 47/022).

Key constructional point. Claim 1 is the sole independent apparatus claim and is deliberately broad: it does not recite a refrigeration system, a solenoid, a hot-gas port, a spring, a valve body, or a module assembly. Those are pushed to claims 3–13. So the § 103 fight on claim 1 turns on a narrow set of elements:

1. a dual piston assembly — inner and outer piston movable relative to each other to control pressure equalization flow;
2. an adjustable control stem engageable with the outer piston, such that the valve (when opened with a pressure differential) yields a fluid equalization flow in a first position and a progressively increasing fluid equalization flow when adjusted to a variable second position;
3. a plurality of bleed orifices on the inner piston openable by movement of the outer piston relative to the inner piston;
4. two orifice sets — first set open during the lower flow; first set + a variable portion of the second set open during the progressively increasing flow.

Claim 14 mirrors this as a method of forming. Note the cross-reference to the previously generated section: the granted claim 1 wording differs from the pre-grant publication (US 2021/0095904 A1), which recited "when the valve is opened with a large pressure differential, a low fluid equalization flow … and a progressively increasing fluid equalization flow." The granted text drops "large" and "low," which makes claim 1 broader than the published version — and correspondingly easier to invalidate. That is a real flag: if the granted claim is the operative text, the "low flow" ceiling that might have distinguished prior art is gone.

2. The references of record — actual disclosures

2.1 US 9,145,978 B2 — "Adjustable fail-safe suction stop valve" (Parker Hannifin; issued 2015-09-29)

(Appears in the "Similar Documents" listing — not in the "Patent Citations" list. I flag this because it is the single most probative reference and, notably, is the applicant's own prior patent.)
Sources: https://patents.google.com/patent/US9145978; https://patents.justia.com/patent/9145978; https://patentimages.storage.googleapis.com/2e/60/93/3087be639fc88e/US9145978.pdf; PCT publication WO 2011/063375.

It discloses a normally open, dual-piston suction stop valve for hot-gas defrost:

• valve body 16, inlet 12, outlet 14, intermediate valve seat 18;
• first (main) piston 30 carrying valve member 34 mating seat 18; biasing member 36 normally biasing the valve member away from the seat (normally open);
• adapter body 72 with top cover 70 secured to the open end of bore 32; hot gas inlet 80;
• second piston 40 reciprocal in a bore 42 in the adapter body, having a portion 44 extending into bore 32 for contacting the first piston 30 — and critically, "the portion 44 … may be axially adjustable to optimize the partial opening of the valve 10 when the second piston 40 is pushed fully downward toward the first piston 30";
• a bleed hole 38 through the first piston providing a fluid pathway from outlet 14 to bore 32;
• solenoid assembly 20 controlling pilot gas to the tops of both pistons; check valves 60, 62;
• an adjusting stem assembly 90 whose threaded stem 92 "protrudes from the valve 10 enabling external adjustment access" and sets the activation pressure at which the valve fully opens (5–40 psi over suction);
• operation: after defrost, solenoid de-energizes; main piston 30 travels up until it hits the bottom 44 of the secondary piston 40, which holds it in a partially open position, and high-pressure gas "can now bleed off through the main valve port 32 in a controlled manner"; when coil pressure can no longer overcome the adjustable spring tension, the secondary piston releases and the main spring pushes the valve fully open.

This reference alone supplies: dual pistons; relative movement between them; an externally adjustable, threaded stem that sets an axially adjustable stop governing the degree of partial (limited) opening; spring bias to open; solenoid-port hot-gas actuation; and a remote/adapter "module" bolted to a body.

2.2 WO 1988/004383 A1 = US 4,877,046 — A/S Finsam Int'l, "Closing and injection valve especially for hot gas defrosting" (cited by examiner)

Sources: https://patents.google.com/patent/WO1988004383A1/en; https://patents.justia.com/patent/4877046.

Discloses a hot-gas-defrost refrigeration shut-off valve in which:

• the valve stem 28 is hollow with openings 46 into its interior, and a cap 40 forms an annular chamber 44 communicating with those openings through a throttle passage 47;
• "the piston is mounted for axial movement on the valve stem" — piston 36 rides between shoulder 41 and cap 40 — and, after the valve head seats and the stem halts, further movement of the piston relative to the stem opens a passage into the openings 46 in the stem, injecting fluid;
• spring 34 acts on the piston; a pressure equalization passage 38 is formed in the guide wall; a throttle passage 60 is provided in the stem; a solenoid valve 10 supplies hot gas to close the valve; the whole is a flanged, cartridge-like assembly (guide 26 clamped between housing 12 and cylinder housing 22).

This is the cleanest teaching in the record of the core structural concept: two members that move relative to one another, where the relative movement itself uncovers ports/passages in the inner member to establish a controlled (throttled) bleed flow, in a hot-gas-defrost valve with a spring and a solenoid.

2.3 US 6,688,319 B2 — Flow Design, Inc., "Flow regulating control valve …" (the only reference marked cited by examiner)

Sources: https://patents.google.com/patent/US20030192597; https://pubchem.ncbi.nlm.nih.gov/patent/EP-1353254-A3 (EP 1 353 254 A3, same family).

Discloses a control valve with: a housing having upstream/downstream regions and a control orifice; a piston slidably disposed in the housing having an edge adjacent the downstream region; an elastic member opposing translation of the piston; a throttling element/​throttling surface adjacent the piston edge, the surface and edge together defining a throttling orifice therebetween; and an equalization aperture admitting downstream fluid into an equalization chamber defined between the housing inner surface and the piston outer surface. The related Sko-Flo/Kirchner family (US 7,770,595; US 2006/0081295) expressly teaches a piston whose sidewall opening is progressively/exponentially exposed as the piston projects beyond a bore, with the area "progressively increasing" with travel. Flow Design thus teaches variable, progressively increasing flow area produced by piston translation relative to a surrounding bore/edge, plus an equalization chamber.

2.4 US 5,070,707 — H.A. Phillips & Co., "Shockless system and hot gas valve" (cited by examiner)

Source: https://patents.google.com/patent/US5070707.

Discloses a hot-gas defrost valve in which a pilot solenoid opens a regulatory (restrictive) passage to reduce the pressure gradient and thereby prevent hydraulic shock; a power piston and a counter piston; the moving speed of the pistons "controlled by the piston area, the dimensions of the pilot passage plug and capillary passage, the friction … and the strength of the closing spring"; and, on closing, "small bleed passages in the valve permit the pistons to slowly return the main plug to its closing position. The gentle opening and closing of the valve prevents hydraulic shock." Same field, same problem (preventing shock/damage on re-application of suction), same mechanism family (bleed passages + piston/spring geometry controlling equalization rate).

2.5 US 2017/0205127 A1 — Yantai Jiayou, "Defrosting valve" (cited by examiner)

Sources: https://patents.google.com/patent/US20170205127A1/en; https://patents.justia.com/patent/9945595 (US 9,945,595, same family); https://www.freepatentsonline.com/y2017/0205127.html.

Discloses a defrosting valve with a valve body 2, valve core 5, push piston 3, return tension spring 4, and — in later embodiments — a "small valve core" 8 nested inside a flow channel of the push piston, seated by its own small spring 9, with the valve core having a through hole, "the lower end of the small valve core correspond[ing] to the through hole." The specification states: "If a double-stage differential pressure is required to open the defrosting valve, then the small valve core assemblies such as …" It also discusses deliberately dimensioning port calibers relative to one another (ports at least one standard / 3 mm larger) to set flow resistance, and calibrating travel so the valve core edge sits "in the middle of" a port.

That is an explicit teaching of staged, sequential opening achieved by two nested, relatively movable, spring-biased flow-controlling members, with port sizing used to set the flow resistance.

2.6 References I could not verify

EP 0 088 648 A1 (Jeumont-Schneider, double-seal valve); EP 0 789 174 A2 (Delphi France, "fluid flow control device"); EP 3 115 668 A1 (Azbil, "regulating valve"); WO 2017/021243 A1 (Voith, "fluid flow control device"). These are cited on the face of the patent and by their titles are directed to sealing, flow-control, and regulating valves. I have not read them and do not rely on them below. Every combination I assert is grounded in disclosures I actually retrieved (§2.1–2.5). The ISR/Written Opinion (mailed 2019-03-21) is the second non-patent citation; I have not reviewed its reasoning.

3. Claim 1 — element-by-element difference analysis

Bottom line: with '978 + Finsam '383, every element of claim 1 is disclosed, and the sole "gap" is the specific two-axially-spaced-set architecture — which is supplied by combining Finsam's relative-travel port-uncovering with '978's adjustable travel stop, and optionally Flow Design's progressively increasing orifice area.

4. The § 103 grounds

Ground 1 (strongest): US 9,145,978 in view of WO 1988/004383 (Finsam), optionally further in view of US 6,688,319 (Flow Design)

"Prior art" status flag. US 9,145,978 issued 2015-09-29, more than one year before the '759 effective filing date of 2018-05-16. It therefore appears to be prior art under § 102(a)(1) (patented/printed publication before the effective filing date). The common-ownership exception in § 102(b)(2)(C) does not reach § 102(a)(1) art, and the § 102(b)(1) grace-period exception is time-limited to one year, which has expired. On its face, therefore, the applicant's own earlier Parker patent is available as § 103 art and cannot be "sworn behind." I flag this as a legal-analysis conclusion, not a ruling — it should be confirmed by counsel (inventorship overlap, any terminal-disclaimer/"same invention" issues, and continuity).

Motivation / KSR rationales:

• (C) Known technique, same field, same problem. '978 and Finsam are both hot-gas-defrost refrigeration valves addressing controlled, shock-free equalization of suction. Finsam's stated design objective is precisely the combination of closing and injecting/throttling functions in one simple valve to avoid hydraulic shock (its background criticizes prior pilot-controlled shut-off valves requiring separate control devices). A PHOSITA would look to Finsam when improving '978's controlled-bleed operation.
• (A) Predictable result. Replacing '978's single bleed hole 38 with an axially spaced series of sidewall orifices uncovered as piston 30 separates from piston 40 is a substitution of one known porting scheme for another, yielding the predictable result — more bleed area as the gap grows. Finsam itself teaches that relative piston/stem travel opens ports; Flow Design teaches that such a piston-edge orifice gives progressively increasing area as a function of travel.
• (D) Known device ready for improvement. '978 already has an "axially adjustable" portion 44 governing "partial opening." Once the artisan uses a travel-limiting stop to set the partial-open gap, using that same stop to select how many orifices are uncovered is the natural and predicted consequence — not a new mechanism.
• (F) Design incentive. Both '978 and the '759 background recite the same field need: equalize gradually and adjustably to avoid damaging the evaporator and other components. The '759 specification itself concedes prior use of replaceable orifices to "change the rate of pressure equalization," the only criticism being that they required opening the circuit. That is an admission that the problem and the mechanism were known — leaving only siting of the adjustment externally, which '978 already does ("stem 92 protrudes … enabling external adjustment access").

Result: claim 1 obvious. Claims 3, 4, 5, 8, 15, 17 also fall (see §5).

Ground 2: US 5,070,707 in view of US 6,688,319 and Finsam WO 1988/004383

Cumulative/alternative. '707 supplies the problem statement (prevent hydraulic shock on re-application of suction) and the mechanism family (bleed passages + piston area/spring selection controlling the rate of piston return). Finsam supplies relative-travel port uncovering; Flow Design supplies progressively increasing orifice area with travel. This ground is slightly weaker than Ground 1 because '707's pistons are a power/counter-piston damping arrangement rather than a bleed-orifice architecture, so more reconstruction is required — but it is a legitimate "obvious to try"/design-choice argument, and '707 is of record (cited by the examiner), so it carries no new-material burden.

Ground 3: US 2017/0205127 (Yantai Jiayou) in view of US 9,145,978

'127 supplies two nested, spring-biased valve cores that open in stages under differential pressure, with port calibers used to set flow resistance and travel calibrated so a valve-core edge sits mid-port — i.e., staged flow control where only a portion of an opening is exposed. Combined with '978's dual-piston/adjustable-stem suction-stop architecture, claim 1 is also rendered obvious. Useful as a teaching, suggestion, or motivation reference for the "first set then a variable portion of the second set" limitation.

Ground 4: The pre-grant publication / family member

WO 2019/221785 A1 (the '759 family's own PCT publication) is not itself prior art to the '759 claim (same inventive entity/family). No basis for § 102(b)(1) art. Do not use.

5. Dependent claims

6. The patentee's strongest non-obviousness arguments (and why they are likely to fail or succeed)

1. No reference teaches an adjustable mechanical stop for the outer piston that determines which of two axially separated orifice sets is exposed.
   Strength: moderate-to-good. Finsam's relative travel opens ports, and '978's portion 44 is axially adjustable, but neither expressly frames the stem as an orifice-selecting travel limiter. This is the most credible distinction. It is undermined, however, by '978's express statement that portion 44 "may be axially adjustable to optimize the partial opening," which a fact-finder could readily find is the same function.

2. Continuum/"variable portion" limitation.
   Strength: moderate. If the art taught only a binary two-position valve, the "progressively increasing / variable portion" language could support non-obviousness. But (a) '978's stem is threaded, giving continuous adjustment of the partial-open gap; (b) Flow Design/Sko-Flo expressly teach progressively increasing orifice area with travel; and (c) elongated-slot geometry giving a linear area-vs-travel relationship is basic engineering. Expect this to fall as routine optimization (In re Aller; In re Applied Materials).

3. Claimed combination as a whole is not taught.
   Strength: weak. § 103 does not require bodily incorporation; the test is whether the claimed subject matter as a whole would have been obvious. Each element is individually known and each performs its established function with a predictable result — the classic KSR fact pattern.

4. Secondary considerations.
   There is no evidence of record I can identify of unexpected results, skepticism, industry praise, licensing, or long-felt-but-unmet need tied to the claimed features. If Parker asserts commercial success of its suction-stop valve line, it must establish a nexus to the claim — and the closest commercial product appears to be the same company's own '978 valve, which cuts against nexus and simultaneously strengthens the § 103 case (the improvements would be predictable refinements of the assignee's own prior design). Also note the specification's admission that "prior attempts … included providing valves that use replaceable orifices that enable the rate of pressure equalization across the valve to be adjusted" — an admission that the problem and the equalization-rate-adjustment function were known; only the external siting is asserted as new, and '978 already provides external adjustment access.

7. Overall conclusion

Claim 1 and claim 14 are, in my assessment, likely invalid under § 103 over US 9,145,978 B2 in view of WO 1988/004383 (Finsam) — the most compelling ground, since '978 supplies the normally-open dual-piston hot-gas-defrost suction-stop valve with an externally accessible, threaded, axially adjustable member governing the degree of partial opening, and Finsam supplies the relative-travel-uncovered port mechanism in the identical field and for the identical purpose. Adding US 6,688,319 (Flow Design) or the Sko-Flo/Kirchner teaching supplies the progressively increasing orifice area limitation. US 5,070,707 is cumulative on the problem and mechanism. US 2017/0205127 (Yantai Jiayou) reinforces the staged/nested two-stage opening concept.

Claims 3, 4, 5, 8, 13, 15, 16 fall with the independent claims. Claims 9–10 (threaded connections, packing nut) are highly vulnerable as conventional mechanical expedients. Claims 2, 6, 7 and 18 are vulnerable on design-choice/conventional-expedient grounds. Claims 11–12 (visual indicator) and 17 are the most defensible, depending on whether a KSR "known technique applied to a ready-for-improvement known device" argument can be substantiated for stem indicia in this art — an argument that gains force because '978 already requires the stem to protrude for external access.

The most important practical point: the closest and most damaging art is the applicant's own earlier US 9,145,978, which was on sale/patented more than a year before the '759 priority date and therefore appears to be § 102(a)(1) art not saved by the common-ownership exception. Any validity defense must reckon with '978 first.

8. Confidence, limitations, and things to verify

High confidence: the substance of the claim-1 and claim-14 elements; the disclosure content of US 9,145,978, WO 1988/004383/US 4,877,046, US 5,070,707, US 2017/0205127, and Flow Design EP 1 353 254 A3/US 6,688,319 — all quoted or closely paraphrased from retrieved text.

Moderate confidence: the exact scope of Finsam's port/relative-travel teaching as applied to an inner piston surrounded by an outer sleeve (the '759 geometry is inverted relative to Finsam's stem-inside-piston arrangement); and the precise phrase-level correspondence of '978's stem to the claimed "control stem engageable with the outer piston." Claim-1 wording should be verified against the USPTO PatentCenter claims PDF, given the granted-vs-published discrepancy flagged in the previously generated summary.

Not verified / do not rely on: the disclosures of EP 0 088 648 A1, EP 0 789 174 A2, EP 3 115 668 A1, WO 2017/021243 A1, and the reasoning of the PCT ISR/Written Opinion (2019-03-21). I was unable to retrieve specification text for these in this session. EP 0 789 174 (Delphi) and WO 2017/021243 (Voith), both titled "fluid flow control device," and EP 3 115 668 (Azbil, "regulating valve") are on their face likely relevant to the adjustable-flow-control and multi-piston aspects and should be pulled and reviewed before any final opinion.

Also worth pulling (not in the Prior Art section, so not relied on above, but flagged): US 7,905,467 B2 ("Dual position pilot operated valve assembly") appears in the page's Similar Documents list and is directly on point by title — I could not retrieve its disclosure. The Sko-Flo/Kirchner family (US 7,770,595; US 2006/0081295) surfaced strongly in searching and its progressively-exposed-sidewall-port teaching would materially strengthen Ground 1 if verified as prior art.

No inconsistency found between the supplied authoritative full text and the retrieved reference texts. The one internal inconsistency to carry forward is the claim-1 wording delta between the granted text and the pre-grant publication, which broadens claim 1 in the granted form and therefore helps an obviousness challenge — flag it to counsel.