US 8393031

I'll search for docket and litigation information on this specific patent number, then summarize.

Let me run one more targeted search for any 2026 appellate docket naming this patent.

US Patent 8,393,031 B2 — Analyst Summary

Important prefatory note on scope of this response: The core bibliographic and claim data below comes from the authoritative full text of the patent (Google Patents, fetched 2026‑10‑01). Litigation/docket information comes from live web search results and is flagged where uncertain. I ran targeted searches of publicly indexed USPTO/PTAB materials and docket aggregators; I found no Federal Circuit (CAFC) appeal docketed in 2026 that names US 8,393,031 as a patent‑in‑suit. I cannot rule out a 2026 appeal that is not yet reflected in indexed sources, so treat "no 2026 CAFC appeal found" as a negative search result, not a certainty.

Bibliographic data

Abstract

A device for cleaning an immersed surface includes a body and members for driving the body over the immersed surface; a filtration chamber provided in the body and having a liquid inlet, a liquid outlet, and a hydraulic circuit for liquid flow between the inlet and outlet through a filtering device. The filtering device includes a first filtering shell extending toward the rear of the body from a front opening, and a second shell fitted to the first shell at the front. The shells fit together to form an integral filtering casing in which the second shell closes the front opening of the first shell except for a liquid inlet passage. The two shells can be separated by disengaging the front opening of the first shell, which then acts as an emptying opening.

Plain‑language overview of the independent claim

There is one independent claim — claim 1 (claims 2–4 are dependent):

Claim 1 — a swimming pool cleaner, comprising:

• (a) a body with an inlet, an outlet, a filtration chamber, and a "rear"; and
• (b) a filtering device positioned between the inlet and the outlet, made of two parts:
  • (i) a first shell having (A) an opening with a first cross‑section and (B) peripheral filtering walls extending toward the rear of the body to define a debris recovery space where debris entrained in the entering water is retained;
  • (ii) a second shell fitted to the first shell so as to close the opening of the first shell except for a water inlet passage that forms a water inlet opening into the debris recovery space;
• with four functional conditions:
  1. the water inlet opening has a smaller cross‑section than the first shell's opening;
  2. the two shells are configured to be fitted together to form an integral filtering casing mounted in the filtration chamber;
  3. the filtering casing is removable in one piece from the filtration chamber while the body is upright on a horizontal surface (i.e., top‑access removal, no need to invert the unit);
  4. once the casing is removed in one piece, one shell may be moved relative to the other to empty debris from the recovery space.

Dependent claims (narrowing only):

• Claim 2 — the relative shell movement for emptying may be done without any tool.
• Claim 3 — the first shell comprises (a) a frame defining openings and (b) a filtering sheet extending across the openings, together at least partially forming the peripheral filtering walls.
• Claim 4 — at least one of the first and second shells comprises a handle.

In substance, claim 1 claims a pool cleaner whose filter is a two‑shell, clamshell‑style removable casing: one shell is the debris basket, the other is the inlet duct/cap that partially blocks the basket; the assembled casing slides out of the top as a single unit, and the shells then separate for emptying.

Litigation / docket context (search‑derived; verify before relying)

• ITC Inv. No. 337‑TA‑1326 (Certain Robotic Pool Cleaners and Components Thereof): instituted 2022‑08‑29 on a complaint by Zodiac Pool Systems LLC and Zodiac Pool Care Europe asserting, among others, claims 1–4 of the '031 patent (and claims 1, 2, 7 of US 8,393,029). Respondents: Wybotics Co. Ltd. (f/k/a Tianjin Wangyuan) and Tianjin Pool & Spa; Aiper entities. Per Chinese trade sources and an HKEX filing, the investigation was terminated in March 2023 — Aiper settled (consent order) and Zodiac withdrew as to Wybotics — so there was no final merits ruling on infringement or validity. (Sources: USITC notice PDF; Federal Register 2022‑18911; govinfo FR‑2023‑06013.)
• District court cases listed for the family include 2:22‑cv‑05271 and 2:25‑cv‑08526 (C.D. Cal.) and 2:25‑cv‑00582 (E.D. Tex.). In the E.D. Tex. action (Zodiac Pool Systems LLC v. Wybotics Co. Ltd., filed 2025‑05‑23), the '031 patent is asserted; a publicly posted complaint analysis states the '031 theory targets the accused cleaners' filter systems as "two shells that function together as a single casing." (Sources: ex‑parte complaint analyses; Unified Patents litigation links on the Google Patents family page.)
• Related 2025–2026 activity: Wybotics filed a DJ action (2:25‑cv‑08526) seeking a declaration that US 8,393,029 and 8,393,031 are invalid, and filed IPR2026‑00158/‑159/‑160 at the PTAB on 2025‑11‑25. Per the petitioner's stipulation (dated 2026‑03‑31) and IPR records, those IPRs challenge only the camera/vision patents US 11,003,191, 11,262,766, and 11,880,207 — not the '031 patent. So the '031 validity challenge appears to be proceeding in the district‑court DJ action, not in an IPR.
• CAFC 2026: no 2026 Federal Circuit docket naming 8,393,031 was located. The only 2026 Federal Circuit items my searches surfaced were unrelated matters (e.g., a LifeCORE/Woodway rehearing petition; a docketing notice in a Court of International Trade case).

Uncertainty flags

• Whether the C.D. Cal. and E.D. Tex. cases have produced any claim‑construction or validity rulings on the '031 claims is not established by the sources found; both were described as at early stages.
• The family page notes "First worldwide family litigation filed" via Darts‑ip, but I did not retrieve a Darts‑ip record specific to the '031 patent, so any additional foreign proceedings (beyond the Paris proceeding against Wybotics, which involves European patent EP 2 240 653, a different patent) are unverified.
• Adjusted expiration (2029‑07‑23) is stated on a "no legal conclusion" basis by the source and reflects term adjustment; it is not a legal determination.

Would you like me to attempt a deeper pull on the C.D. Cal. 2:25‑cv‑08526 and E.D. Tex. 2:25‑cv‑00582 dockets, or on ITC EDIS record for 337‑TA‑1326?

I'll research the litigation history for US 8,393,031. Let me start with the leads already present in the patent record and then verify/search for more.

Good leads. Let me dig deeper into each case and the ITC investigation.

Litigation Involving U.S. Patent No. 8,393,031

Patent identified as: US 8,393,031 B2 — "Apparatus for cleaning a submerged surface with removable filtration device"; current assignee Zodiac Pool Care Europe SAS; priority date Dec. 21, 2007; granted Mar. 12, 2013.

I found four distinct proceedings in which the '031 patent was asserted or challenged. All involve the same family of parties (Zodiac vs. Wybotics/Aiper). I did not find any CAFC appeal involving the '031 patent.

1. ITC Investigation No. 337-TA-1326 — Certain Robotic Pool Cleaners and Components Thereof

• '031 patent asserted: Claims 1–4 (the patent's entire claim set), alongside claims 1, 2, and 7 of U.S. 8,393,029.
• Outcome/Status: Terminated. Counsel for Zodiac (Kilpatrick Townsend) states the Aiper entities settled on confidential terms, producing a consent order barring Aiper from importing or selling the accused products, and that Wybotics gave sworn representations it had stopped manufacturing, importing, and selling the accused products in the U.S. Wybotics' counsel (Jones Day) states the complainants voluntarily withdrew their claims and moved to terminate the investigation; a trade-report summary describes the termination as "without import restrictions." The investigation therefore ended without an exclusion order as to Wybotics.
• Sources: USITC notice of institution; USITC press release; Kilpatrick Townsend (Zodiac counsel); Jones Day (Wybotics counsel)

2. Zodiac Pool Care Europe v. Wybotics, Co. Ltd. et al., No. 2:22-cv-05271 (C.D. Cal.)

• This was the district-court companion to ITC 337-TA-1326 asserting the '031 (and '029) patents.
• Outcome/Status: The case was stayed pending the ITC investigation and administratively closed/terminated Jan. 4, 2023 (JS‑6). Aiper was dismissed with prejudice on March 27, 2023 (subject to a sealed term sheet incorporated into the dismissal order). Wybotics and Tianjin Pool & Spa were dismissed without prejudice on March 29, 2023.
• Source: Patexia docket

3. Zodiac Pool Systems LLC et al. v. Wybotics, Co. Ltd. (f/k/a Tianjin Wangyuan Environmental Protection and Technology Co., Ltd.), No. 2:25-cv-00582 (E.D. Tex.)

• Asserted patents: the '031 and '029 patents (legacy gear/filter-basket designs), plus U.S. 11,003,191; 11,262,766; and 11,880,207 (camera/vision features). The complaint seeks damages and injunctive relief.
• Outcome/Status: Pending. Procedural activity through late 2025 includes a Rule 12(b)(5) motion to dismiss for insufficient service by Wybotics, a scheduling conference, and related sealing motions. Wybotics states Zodiac amended its complaint on Sept. 22, 2025, and that the parties resolved the service dispute on Oct. 30, 2025. No trial date set as of the record reviewed.
• Sources: Justia docket; Wybotics disclosure citing "2:25-cv-582-JRG-RSP (E.D. Tex. Filed May 23, 2025)"; HKEX filing

4. Wybotics Inc. v. Zodiac Pool Systems LLC, No. 2:25-cv-08526 (C.D. Cal.)

• This is a declaratory-judgment action for non-infringement and invalidity, including a challenge to the validity of the '031 and '029 patents, along with the camera patents (11,003,191; 11,262,766; 11,880,207). Wybotics also filed IPR petitions on Nov. 25, 2025 — but those IPRs target the camera patents only, not the '031.
• Outcome/Status: A docket aggregator lists this case as "Closed" (PACER-derived). Note: I have not been able to confirm whether this closure is a full dismissal versus a statistical/transfer closure, so treat the closure characterization as provisional. The merits challenge to the '031 is noted as having been raised in this DJ action rather than through an IPR.
• Sources: Ex Parte case page; complaint analysis

Notes, Caveats, and Things I Could Not Confirm

• The '031 patent appears to have been litigated only against Wybotics/Tianjin and the Aiper entities. I found no other defendants for this specific patent. The 2014 Zodiac v. Aqua Products suit in the Southern District of California asserted U.S. 8,615,836 (the "disconnectable dirty circuit" patent) — a different patent — so it is not '031 litigation.
• France proceeding: Zodiac's French action against Wybotics concerns the French counterpart (FR 2,925,551), not the U.S. '031, so it is outside the scope of your request but relevant context.
• I did not locate any CAFC appeal specifically involving the '031 patent. The 2022 C.D. Cal. case terminated by dismissal/administrative closure, and the 2025 cases are at the district-court level.
• Status volatility: Cases 3 and 4 were filed recently (2025) and remained active during the record I reviewed (latest docket activity late 2025; Wybotics' PTAB papers dated March 31, 2026). Current status as of today (April 26, 2026) may have changed.
• I am reasonably confident in the party names, courts, case numbers, and filing dates above because they are corroborated across USPTO/ITC/government sources, docket aggregators, and the litigation counsel's own published case descriptions. I am less certain about the precise final disposition of the 2025 cases and would verify against live PACER before relying on them.

Bottom line: U.S. 8,393,031 has been asserted in one ITC investigation (337-TA-1326), one C.D. Cal. infringement suit (2:22-cv-05271), and one E.D. Tex. infringement suit (2:25-cv-00582), and its validity/non-infringement is challenged in a C.D. Cal. declaratory-judgment action (2:25-cv-08526). The 2022 matters ended by settlement/consent order and voluntary dismissal; the 2025 matters were still being litigated at the latest points in the record.

I'll verify the structured "no proceedings on file" signal against public sources before writing this up.

Let me run a few more targeted checks against PTAB dockets, the ITC proceeding, and any related IPR filings.

Let me check the 2025–2026 litigation wave and any IPRs filed against Zodiac's '031 in that period.

Proceedings overview

Total AIA trial proceedings on file for US 8,393,031: zero — no IPR, no PGR, no CBM, ever filed. The canonical USPTO Open Data Portal "PTAB proceedings on file" block returns no AIA trial proceedings for this patent as of the most recent ingest, and my independent searches of PTAB-related public sources surfaced no petition against the '031 patent by any party. Status breakdown is therefore: 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, 0 institution denied.

The defensive posture this gives you is the opposite of "hardened": claims 1–4 are entirely untested at the PTAB, and no petitioner has ever triggered § 315(e)(2) estoppel. That cuts both ways — you get the full run of prior art in district court with no estoppel straitjacket, but you also cannot point a judge at an earlier Board decision invalidating anything. The patent has been asserted repeatedly (ITC, C.D. Cal., E.D. Tex., France) and has never drawn an IPR, which is itself worth a hard look at why — see the strategic summary.

Because there are no proceedings to profile, the per-proceeding sections below are replaced with (a) a statement of what the structured record actually shows, and (b) the non-PTAB challenges that a defendant should know are on the record.

No proceedings to profile

The structured "PTAB proceedings on file" block is the canonical source for this task, and it is empty for US 8,393,031. I did not locate any of the following, and I am explicitly declining to invent proceeding numbers, panels, or dispositions:

• No IPR, PGR, or CBM petition against US 8,393,031 (application 12/808,444; priority 2007-12-21; granted 2013-03-12).
• No Final Written Decision addressing any claim of the '031 patent.
• No PTAB appeal to the Federal Circuit arising from the '031 patent.
• No patent-owner motion to amend as to the '031 patent.

Fabrication guard: I could not confirm any proceeding number, panel, institution date, or FWD for this patent, because none exists on the public record I can find. Anything with a specific case number attached to the '031 patent would, on this record, be fabricated.

One important near-miss to rule out

The PTAB activity you will find when searching "Zodiac" + "IPR" is Zodiac Pool Systems, Inc. v. Aqua Products, Inc., IPR2013-00159, which went to a Final Written Decision (Paper 71, 2014-08-22) on U.S. Patent No. 8,273,183 and produced the Federal Circuit's Aqua Products, Inc. v. Matal, 872 F.3d 1290 (Fed. Cir. 2017) (en banc on the motion-to-amend burden). That proceeding is not about US 8,393,031 — Zodiac was the petitioner there, and the patent was Aqua's '183 patent. Do not cite it as an '031 outcome. It is only relevant as background: Zodiac is an experienced PTAB litigant on both sides of the table.

Non-PTAB challenges on the record (context, not PTAB proceedings)

These are not AIA trials and should never be described as such, but they define the assertion posture you are walking into.

ITC Inv. No. 337-TA-1326 — Certain Robotic Pool Cleaners and Components Thereof

• Type: Section 337 investigation (not a PTAB proceeding)
• Filed: complaint 2022-07-29; instituted 2022-08-29; published 2022-09-01
• Asserted claims of the '031 patent: claims 1–4 (all four claims of the patent), alongside claims 1, 2, and 7 of US 8,393,029
• Respondents: Wybotics Co. Ltd. (d/b/a Winny Pool Cleaner), Tianjin Pool & Spa Corporation, Aiper entities
• Outcome: terminated in 2023-02 without any final substantive determination on infringement or validity — Zodiac voluntarily withdrew after settling with Aiper (confidential terms, resulting in a consent order barring Aiper from importing/selling the accused products), and Wybotics represented it had ceased making/importing/selling the accused products. Complainants' counsel (Kilpatrick Townsend) publicly describe the result as stopping infringement "before trial."
• Defensive value: There is no ITC validity ruling you can borrow or must fear. An ITC termination by withdrawal is not a merits adjudication and creates no estoppel.
• Sources: USITC institution notice, 87 FR 53788 (2022-09-01)

District court assertions

• 2:22-cv-05271 (C.D. Cal.) — Zodiac Pool Care Europe v. Wybotics Co. Ltd. et al., companion to the ITC action. (Unified Patents docket link)
• 2:25-cv-00582 (E.D. Tex.) — Zodiac Pool Systems LLC v. Wybotics Co Ltd. The '031 patent is asserted; the complaint targets the two-shell removable filter-casing architecture and also pleads claims of the '029 patent and the camera-based '191 / '766 / '207 patents. (docket)
• 2:25-cv-08526 (C.D. Cal.) — Wybotics Inc v. Zodiac Pool Systems LLC, a declaratory judgment action filed 2025-09-09 seeking non-infringement of all asserted Zodiac patents and a declaration that US 8,393,029 and US 8,393,031 are invalid. (docket)

The 2025 IPR wave — and why it does not touch the '031 patent

Wybotics's public disclosures (HKEX prospectus materials, 2026) state that on 2025-11-25 it filed an IPR at the USPTO challenging Zodiac's camera/vision patents — US 11,003,191, US 11,262,766, and US 11,880,207 — and that it is pursuing invalidity of the '029 and '031 patents through the DJ complaint rather than the PTAB. So the mechanism Wybotics chose against '031 is an Article III validity challenge, not an AIA trial. (I flag this as the most likely source of a future '031 petition, but as of the structured data and my searches, none has been filed.)

Strategic summary

Claim-by-claim status. All four claims of US 8,393,031 — claim 1 (independent), claim 2, claim 3, claim 4 — are UNTESTED at the PTAB. None is canceled. None has been confirmed in an FWD. None has been amended. Claim 1 recites the two-shell / integral filtering casing / one-piece removal / shell-separation-for-emptying combination; claims 2, 3, and 4 add the no-tool limitation, the frame-plus-filtering-sheet limitation, and the handle limitation respectively. If a demand letter asserts these claims, the patent owner has a full, clean claim set with no prosecution or PTAB history to explain away — but equally, no adjudicated validity.

Estoppel landscape. There is no § 315(e)(2) estoppel attaching to this patent from any petitioner, because no IPR/PGR was ever instituted. For a defendant today that means: every § 102/§ 103 ground you can find — including art that a hypothetical prior petitioner "reasonably could have raised" — remains available in district court, the ITC, and the DJ action. There is also no § 325(e)(1) estoppel problem for Wybotics in the co-pending DJ case, because it filed its IPRs against the sibling vision patents, not against '031. Practically, this is the single most defendant-favorable feature of the '031 landscape: your invalidity case is unconstrained.

Pattern signals. No defensive aggregator (Unified Patents, RPX, etc.) appears anywhere in the chain for this patent. The same challengers (the Wybotics/Tianjin Wangyuan and Aiper groups) have been on the receiving end across ITC, C.D. Cal., E.D. Tex., and French proceedings, yet have not petitioned the Board on the '031 patent — instead taking the '031 validity fight into a DJ action and, in the French proceeding, a counterclaim of invalidity against the corresponding French patents. That is a meaningful signal in both directions: either the '031 prior-art story is weak (so challengers prefer claim-construction and non-infringement defenses), or challengers are saving the § 315 window. Note the patent's clock: ODP lists the adjusted expiration as 2029-07-23, so the remaining enforceable life is roughly three years — which materially reduces the return on a multi-year IPR campaign and may itself explain why none has been filed.

Caveat on the record. Wybotics's prospectus is a party's own characterization of its litigation, not a PTAB order; I rely on it only for the proposition that its IPR filings target the '191/'766/'207 patents, not the '031 patent. The '031 patent's own PTAB docket is empty.

Recommended next steps

• If you are a defendant being asserted on the '031 patent: treat the empty PTAB docket as an opportunity, not a comfort. You face no estoppel and a fully open prior-art field. The ITC action was resolved by withdrawal and consent order with no validity adjudication, so the prior art marshalled by the 2022 respondents (or their successors) is still live. Do not assume any of it has been tested or spent.
• Timing. With an adjusted expiration of 2029-07-23, an IPR petition filed today would land an institution decision roughly six months out and an FWD at the statutory one-year-from-institution deadline — i.e., concluding very close to the end of the patent's life. Weigh a § 315(b) one-year-bar-compliant IPR against a district-court invalidity defense on the merits; the co-pending DJ action (2:25-cv-08526) already gives Wybotics a vehicle to litigate invalidity of the '031 patent without PTAB, and pairing a DJ invalidity count with an IPR would invite a § 315(a)(1)/(b) analysis and potential discretionary denial under Fintiv-type factors if the DJ case has progressed.
• Confirm the negative directly. Before relying on this write-up, verify against the primary sources: USPTO PTAB E2E / PTAB Center for the '031 patent's trial docket, and CourtListener for any Federal Circuit appeal naming US 8,393,031. ODP ingest can lag recently filed petitions; if a 2025–2026 '031 petition surfaces, it is not reflected in the structured data I was given.
• If you are the patent owner and want to know where you stand: four claims, all intact, no estoppel, ~3 years of life left, and a challenger that has already committed to a DJ invalidity attack. Your exposure is the DJ action and the E.D. Tex. case — not the Board.

I'll start by verifying the assignment record and cross-referencing litigation and corporate status.

Let me verify whether any post-issuance assignments exist and check the litigation parties.

Ownership & Assignment Analysis — US 8,393,031 B2

Patent: Apparatus for cleaning a submerged surface with removable filtration device
App. No.: 12/808,444 (US national phase of PCT/FR2008/052339)
Priority: 2007-12-21 (FR 0708996) · Filed: 2008-12-17 · Granted: 2013-03-12
Assignee of record: Zodiac Pool Care Europe SAS

Data note: The USPTO Assignment Center (assignmentcenter.uspto.gov) exposes the correspondent of record for each recording. In this analysis I relied on the Google Patents legal-events mirror of the USPTO assignment record. That mirror reproduces reel/frame, conveyance, assignor/assignee, and dates, but it does not expose the correspondent attorney/agent. I do not have the correspondent for this patent and will not invent one. Where the correspondent would be decisive, I flag it as a gap rather than infer.

Inventors

Basis for employer attribution: both inventors executed the assignment (reel 025012/0477) in favour of Zodiac Pool Care Europe, and Pichon appears as the named inventor on an earlier Zodiac-lineage filing cited against this patent — US 2007/0251032 A1, "Immersed Surface Cleaning Device Provided with a Nonreturn Inlet Conduit" (2004-04-14). This is a repeat Zodiac inventor household, i.e. an in-house R&D team, not an acquired-from-third-party invention.

Unusual patterns: None detected. The relevant tell here is the inverse of a fire-sale precursor — the inventors assigned to the French operating parent and (on the record available) neither departed nor triggered any re-assignment of the patent. I have no evidence of inventor departure within 12 months of filing, and I have no employment-agreement or HR data that would let me confirm departure either way; treat that as unverified rather than "clean."

Original assignee

Zodiac Pool Care Europe SAS — ZA La Balme, 31450 Belberaud, France. Listed as current assignee on the face of the patent.

• Primary line of business: design, manufacture and sale of swimming-pool maintenance and water-quality equipment (cleaners, pumps, filtration, sanitisation). Zodiac Pool Care Europe was created in 1998 and describes itself as handling "operations related to maintenance and water quality" — i.e. an operating manufacturer, not a holding vehicle.
• Product embodying the claims: Yes. This patent is part of the family that covers Zodiac's robotic pool-cleaner filtration architecture. The claims recite a "swimming pool cleaner" with a two-shell filtering casing removable in one piece; Zodiac's robotic cleaners are the practising commercial embodiment. Corroborating evidence that the family is product-bearing rather than paper: sibling patents in the same "Similar Documents" cluster (US 8,397,330; US 8,397,331; US 8,393,029; US 8,393,033; US 8,762,187, etc.) are all granted, co-pending Zodiac cleaner patents.
• Current status: Operating, and consolidated. Zodiac joined the Fluidra group in 2018 (Fluidra is a Spanish-listed multinational; the Zodiac Pool Care Europe SASU legal entity still appears on Zodiac's own affiliate list). Earlier, Zodiac Pool Care Europe SAS absorbed Zodiac International SAS (it is named as "sociedad absorbente" of Zodiac International in Spanish CNMV filings). The entity is therefore live and its corporate parent is publicly traded.

Caveat: the Zodiac International absorption is confirmed in corporate registry documents, not in a USPTO assignment recorded against this patent. I found no USPTO recording of that merger for the '031 patent. Recorded ownership on the patent still reads Zodiac Pool Care Europe.

Assignment timeline

The USPTO record for US 8,393,031 contains exactly one recorded assignment. There is no post-issuance chain of any kind.

• 2010-09-08 (executed) / recorded 2010-09-20 — Reel 025012/0477
  • Conveyance: Assignment (ASSIGNMENT OF ASSIGNORS INTEREST)
  • Assignor: Pichon, Philippe (Mr.) and Mastio, Emmanuel (Mr.)
  • Assignee: Zodiac Pool Care Europe (France)
  • Correspondent: Not retrievable from the source used. The mirror shows no correspondent field for reel 025012/0477; the Assignment Center would. No recurrence can be established, because there is only one recording in the chain — the "repeat correspondent" tell is structurally unavailable here.
  • Context: Internal/ordinary-course inventor assignment. Executed ~2.7 years after the 2008-12-17 filing, consistent with perfecting title on entry to US national phase from PCT/FR2008/052339, not with any monetisation event.

No other assignments recorded. Google Patents legal events for this patent list only: AS (assignment, 2010-09-20), FEPP (2012-12-02), STCF (patent grant, 2013-02-20), FPAY 4th year (2016-09-12), MAFP 8th year (2020-09-14), MAFP 12th year (2024-09-12). Maintenance fees were paid through the 12th year by a large entity — consistent with a continuing corporate owner, not a lapsed shell.

Timeline diagram

timeline
    title Ownership and assertion history of US 8393031
    2007 : Priority FR 0708996 filed
    2008 : PCT filed by Zodiac Pool Care Europe
    2010 : Inventors assign to Zodiac PCE
         : Reel 025012 frame 0477
    2011 : US application published
    2013 : Patent granted to Zodiac PCE
    2018 : Zodiac group joins Fluidra
    2022 : ITC complaint 337-TA-1326
         : C D Cal suit 2 22-cv-05271 filed
    2023 : Aiper consent order at ITC
         : Wybotics dismissed from ITC case
    2025 : New district court suits filed

NPE / troll-pattern signals

Supporting assertion facts (from ITC/GovInfo and firm records):

• Complainants in Inv. 337-TA-1326, filed 2022-07-29: Zodiac Pool Systems LLC (2882 Whiptail Loop East #100, Carlsbad, CA 92010) and Zodiac Pool Care Europe (ZA La Balme, 31450 Belberaud, France) — asserting claim infringement of US 8,393,029 and US 8,393,031. Federal Register notice: https://www.govinfo.gov/content/pkg/FR-2022-09-01/pdf/2022-18927.pdf
• Respondents: Wybotics Co. Ltd. (f/k/a Tianjin Wangyuan), Tianjin Pool & Spa Corporation, Shenzhen Aiper Intelligent Co. Ltd., Aiper Intelligent LLC, Aiper Inc.
• Outcome: Aiper settled with a consent order; Wybotics was voluntarily dismissed in 2023-02 (Jones Day reported ~7 months of litigation ending in voluntary withdrawal). KTS Law reports representing Zodiac and obtaining the consent order.
• Parallel district action: Zodiac Pool Care Europe v. Wybotics, Co. Ltd. et al., No. 2:22-cv-05271 (C.D. Cal.). Additional cases cited by Google Patents: 2:25-cv-08526 (C.D. Cal.) and 2:25-cv-00582 (E.D. Tex.).

Verdict

Operating-company assertion

Justification: The entire recorded ownership chain is a single inventor-to-employer assignment (executed 2010-09-08, recorded 2010-09-20, reel 025012/0477) to Zodiac Pool Care Europe SAS, with no subsequent transfer to any licensing vehicle, aggregator, or shell — and the assignee is a French pool-equipment manufacturer with a live corporate parent (Fluidra). The patent is being asserted by its owner and its US affiliate as complainants in ITC 337-TA-1326 and as plaintiffs in C.D. Cal. 2:22-cv-05271, against named competitor products (Wybotics/Wangyuan, Aiper), which is the definition of a competitor-versus-competitor assertion rather than an NPE campaign. No NPE signal scored present; one (repeat correspondent) is structurally unavailable rather than negative.

One open item for a human follow-up: the correspondent of record for reel 025012/0477 was not retrievable from the mirror I used. On this chain it would change nothing — there is only one recording, so no recurrence pattern exists — but it should be pulled directly from the Assignment Center for a complete record.

Verify at: https://assignmentcenter.uspto.gov/ (search App. No. 12/808,444 or Patent 8,393,031) · indexed mirror: https://assignment.uspto.gov/patent/index.html

I'll research US 8,393,031 and its cited prior art. Let me run several targeted searches.

Let me gather details on the key cited references.

Prior-Art Analysis — US 8,393,031 B2

Important caveat on method: I do not have a direct, credentialed interface to the USPTO PatentCenter/Patent Application Information Retrieval systems. The results below were compiled from the Google Patents record for US 8,393,031 B2 (which republishes USPTO front-page citation data), FreePatentsOnline, and the full text of the cited documents themselves. The patent number was searched and interpreted literally as 8,393,031; no near-number substitutions (e.g., 8,393,030 / 8,393,035 / 8,615,836) were folded into the results, though I flag them separately below because they are siblings.

1. The Patent at Issue

Source: https://patents.google.com/patent/[US8393031B2](/patent/US8393031B2)/en

Claims (4 total), summarized:

• Claim 1 — A swimming pool cleaner with (a) a body having an inlet, an outlet, a filtration chamber and a rear; (b) a filtering device between inlet and outlet comprising (i) a first shell with an opening of a first cross-section and peripheral filtering walls extending toward the rear defining a debris recovery space, and (ii) a second shell fitted to the first shell so as to close the opening except for a water inlet passage forming a water inlet opening into the debris recovery space; wherein (i) the inlet opening is smaller than the first cross-section, (ii) the shells fit together to form an integral filtering casing mounted in the filtration chamber, (iii) the casing is removable in one piece when the body is positioned upright on a horizontal surface, and (iv) when removed, one shell is movable relative to the other for emptying debris retained in the recovery space.
• Claim 2 — Same, wherein the shells are movable relative to each other without any tool.
• Claim 3 — The first shell comprises (a) a frame defining openings and (b) a filtering sheet extending across the openings, the frame and sheet at least partially forming the peripheral filtering walls.
• Claim 4 — At least one of the first and second shells comprises a handle.

2. Cited Prior Art — Full Listing

US 8,393,031 B2 carries 12–13 patent citations plus one non-patent citation. Note a discrepancy in the record: Google Patents shows one list headed "Citations (12)" (ending at US 2007/0251032 A1) and a second headed "Patent Citations (13)" that additionally includes US 6,627,074 B2. Both lists are reproduced faithfully below; I have not "corrected" either.

3. Reference-by-Reference Description and § 102 Assessment

Bottom line up front: No single cited reference discloses, in one document, the two-shell filtering casing of claim 1 (a first shell with a front opening and peripheral filtering walls, plus a second shell fitted at the front so as to close that opening except for a smaller inlet passage, the two forming an integral, one-piece-removable casing that separates for emptying). The cited art is therefore best characterized as background art and § 103 combination material, and it is used in the specification chiefly to frame the problem (see column discussion below), not to be anticipatory. My per-claim conclusions are stated candidly.

3.1 US 6,409,916 B1 — Maytronics (1999-08-03 / 2002-06-25) — closest structural prior art

• Description: A pool-cleaning device having an outer shell with a detachable lid and an inner shell; the improvement is a basket-like filter element with a tubular central stem seated on the clean-water exit tube, surrounded by an annular trough that is the active filtering portion; the trough rim is detachably affixed to the inner shell. Solids-laden water enters the trough from above, so the filter is removed from the top without turning the device upside down, and no non-return valves are needed. See https://patents.google.com/patent/[US6409916B1](/patent/US6409916B1)/en.
• § 102 relevance: Potentially relevant to the "removable in one piece when the body is positioned upright on a horizontal surface" and "no tool" concepts (claim 1 clause (iii) and claim 2). However, the element is a single filter element seated on an exit tube — there is no first shell / second shell pair, no second shell closing a first-shell front opening, and no smaller inlet passage defined by the shell interface. It does not anticipate claim 1. The specification itself cites it as the example of a top-access flap with a "particularly complex" hydraulic circuit requiring an oversized pump.

3.2 US 6,013,178 A — Aqua-Vac Systems (1998-10-15 / 2000-01-11)

• Description: A bottom-loading filter assembly (removable bottom covers an opening in the bottom of the outer housing) with a filter housing having spaced U-shaped ends, a pair of stiff rectangular filter elements mounted in vertical channels, and a U-shaped housing member bridging the U-shaped openings. A water inlet port is in the removable bottom and carries flap-type non-return members. See https://patents.google.com/patent/[US6013178A](/patent/US6013178A)/en.
• § 102 relevance: This is the reference the specification calls out for the bottom-flap arrangement requiring non-return valves. Its rigid filter elements held in channels/tracks are arguably relevant to claim 3 (frame defining openings + filtering sheet across the openings) — but the U-shaped ends are a housing, and there is no teaching of a second shell closing a first shell's front opening. Does not anticipate claim 1; at most a § 103 secondary reference against claim 3.

3.3 US 6,473,927 B1 — 3S Systemtechnik AG (1998-09-23 / 2002-11-05)

• Description: A swimming-bath cleaning device (robotic pool cleaner) with an internal filter cartridge circumscribing the water pump; the cartridge extends between the base plate and the housing cover, partitioning a contamination-exposed outer region from a clean inner region. As described in later Aqua Products filings (US 2013/0152317 A1), disassembly requires removing the housing cover and blind re-alignment of the cartridge seals.
• § 102 relevance: Relevant background on top-access cartridge filters and on a single cartridge constituting the filtration boundary. No two-shell structure, no front opening closed by a second shell. Does not anticipate any claim.

3.4 US 2007/0251032 A1 — Pichon (2004-04-14 / 2007-11-01), WO 2005/103416 A1

• Description: "Immersed surface cleaning device provided with a non-return inlet conduit." A filtration chamber has a liquid inlet with a non-return conduit extending through the debris-retention zone, with a free end opening into the retention zone, preventing reverse passage of impurities when pumping is inactive. Because the Applicant (Pichon) is a co-inventor here, this is same-field, same-inventor art.
• § 102 relevance: Directly relevant to the non-return function that US 8,393,031 achieves via the second shell's transverse rear separation wall (specification: "eliminates the need to provide valves or other non-return devices"). It is a strong § 103 reference on the non-return aspect, but it discloses a conduit, not a two-shell filtering casing. Does not anticipate any claim of US 8,393,031.

3.5 US 6,886,205 B1 — Zodiac Pool Care Europe (2000-12-21 / 2005-05-03)

• Description: "Self-propelled running apparatus for cleaning an immersed surface" — same assignee, general self-propelled cleaner architecture (body, drive/rolling members).
• § 102 relevance: General chassis/architecture art only. Does not anticipate any claim.

3.6 US 5,842,243 A — Aqua Products (1997-04-24 / 1998-12-01)

• Description: "Manually propelled pool cleaner" — brush/vacuum pool cleaner with housing and suction pump. (Notably, its own Google Patents page lists US 8,393,031 as a citing document, confirming it is a background citation.)
• § 102 relevance: Generic pool-cleaner structure. Does not anticipate any claim.

3.7 US 4,768,532 A — Jandy Industries (1987-01-23 / 1988-09-06)

• Description: "Underwater pool cleaner" — early underwater suction-type cleaner.
• § 102 relevance: Historical background; no filtration-casing, multi-shell, or front-opening-closure teaching. Does not anticipate any claim.

3.8 US 3,892,282 A — Total Enterprises (1970-04-14 / 1975-07-01)

• Description: "Random motion suction cleaner" — an early random-travel pool/vacuum cleaner.
• § 102 relevance: Very early background art. Does not anticipate any claim of US 8,393,031 (which did not exist as a technology space in 1970–75 in two-shell-casing form).

3.9 FR 2 599 413 A1 — Pappalardo (1986-05-27 / 1987-12-04)

• Description: "Automatic apparatus for cleaning submerged surfaces" — French-language automatic submerged-surface cleaner.
• § 102 relevance: Background. No two-shell filtering casing with front-opening closure. Does not anticipate any claim.

3.10 EP 0 483 470 A1 — 3S Systemtechnik AG (1990-10-31 / 1992-05-06)

• Description: "Self-propelled cleaning device, particularly for swimming pools" — self-propelled pool cleaner.
• § 102 relevance: Background on self-propulsion. Does not anticipate any claim.

3.11 US 2002/0104790 A1 — Lincke (2001-01-30 / 2002-08-08) and US 6,627,074 B2 — Filter Specialists, Inc. (2001-01-30 / 2003-09-30)

• Description: These share a priority date and title ("Filter element for swimming pool cleaner"); US 6,627,074 is the granted version of the same subject matter. They are directed to a removable filter element/cartridge for a swimming pool cleaner.
• § 102 relevance: Relevant to the concept of a removable filter element with a support frame (claim 3) and to handle/removal ergonomics (claim 4), but they do not disclose a two-shell casing, a front opening closed by a second shell, or debris-emptying by shell separation. Do not anticipate any claim.
• Record note: US 2002/0104790 A1 is the sole citation in the 12-item "Citations" list; US 6,627,074 B2 is the additional citation in the 13-item "Patent Citations" list.

3.12 US 2001/0032809 A1 — Henkin (1999-11-15 / 2001-10-25)

• Description: "Electric powered automatic swimming pool cleaning system."
• § 102 relevance: Electrical/control architecture background. Does not anticipate any claim.

3.13 Non-Patent Citation — International Search Report, PCT/FR2008/052339

• Description: The ISR for the parent PCT application.
• § 102 relevance: Procedural, not prior art in its own right; it identifies the art considered during international search.

4. Claim-by-Claim § 102 Conclusion

Overall: The examiner-cited references function as background and § 103 secondary references, not anticipatory art. On the record available to me, no cited reference invalidates any claim of US 8,393,031 under § 102, and the novelty of the granted claims rests on the two-shell, front-opening-closure-with-smaller-inlet-passage, one-piece-removable-and-separable filtering casing.

5. Related Documents That Are NOT Prior Art (flagging to avoid misuse)

The Google Patents "Similar Documents" list shows several patents that a careless search might treat as prior art. They share the same 2007-12-21 French priority date and were filed in the U.S. on 2008-12-17/18 (one day after US 12/808,444's 2008-12-17 filing), so they are co-pending sibling applications, not § 102 prior art:

• US 8,615,836 B2 — "Apparatus for cleaning a submerged surface with a disconnectable dirty circuit" (same inventors/assignee)
• US 8,393,035 B2 — "Submerged surface cleaning apparatus with inlet duct of non-constant cross section"
• US 8,393,030 B2 — "Submerged-surface cleaning apparatus with angled filtration system"
• US 8,627,533 B2, US 8,393,033 B2, US 8,393,034 B2, US 8,397,331 B2, US 8,393,029 B2, US 8,397,330 B2, US 8,763,187 B2 — same Zodiac Dec-2007 family (FR 0708994–FR 0709002).

These are useful context and evidence of the common specification, but they should not be asserted as § 102 art against US 8,393,031.

6. Downstream / Litigation Context (from the same record)

For completeness, US 8,393,031 B2 is flagged in the record as the subject of family litigation:

• U.S. District Court, California Central District: 2:22-cv-05271 and 2:25-cv-08526
• U.S. District Court, Texas Eastern District: 2:25-cv-00582
• U.S. International Trade Commission: 337-TA-1326

(Source: https://patents.google.com/patent/US8393031B2/en). I have not independently verified the current status of these proceedings.

7. Verification Gaps I Want to Be Explicit About

1. I could not run a native USPTO PatentCenter query. The citation list above comes from the Google Patents mirror and the individual documents; the underlying USPTO front-page data is the same, but I have not confirmed the "examiner-cited vs. third-party-cited" asterisk designations against the USPTO OFR/PTAB record itself.
2. The 12-vs-13 citation discrepancy (US 6,627,074 B2 present in one list, absent in the other) is reported as found, not resolved.
3. I did not verify every date in the individual references against the printed front pages — dates shown are those listed in the US 8,393,031 citation table and on the references' Google Patents pages.
4. The § 102 conclusions are analytical, not an examiner's or a court's ruling. They reflect my comparison of the cited disclosures to the granted claims; a full § 102/§ 103 analysis would require the complete specifications and drawings of each reference, which I only partially retrieved.

I'll ground the analysis by pulling details on the key prior-art references cited on the patent page before constructing the § 103 combinations.

Let me pull details on the remaining key references — the Maytronics and Lincke filter elements, and the 3S/Jandy/EP references.

Let me gather details on the remaining cited references (Jandy, Aqua Products, 3S, Henkin, and the non-return inlet art) to complete the mapping.

Obviousness Analysis — U.S. Patent No. 8,393,031 B2

Patent: Apparatus for cleaning a submerged surface with removable filtration device
Inventors: Philippe Pichon; Emmanuel Mastio Assignee: Zodiac Pool Care Europe SAS
Priority: 2007‑12‑21 (FR 0708996) Filed: 2008‑12‑17 (PCT/FR2008/052339) Granted: 2013‑03‑12
Claims analyzed: 1–4 (all claims)

1. Analytical framework

Because the application was filed before March 16, 2013, the pre‑AIA version of 35 U.S.C. § 103 governs, applied through the Graham v. John Deere factors (scope/content of prior art, differences, PHOSITA level, secondary considerations) as refined by KSR Int'l v. Teleflex. The claims are presumed valid, and the burden of proving invalidity by clear and convincing evidence rests on a challenger. All prior art cited on the face of the patent predates the 2007‑12‑21 priority date and therefore qualifies under § 102(a)/(b)/(e).

PHOSITA: a mechanical design engineer with ~3–5 years of experience in robotic pool cleaners and small hydraulic/filtration systems, familiar with the cartridge/bag filter architectures of Aqua‑Vac, Maytronics, Hayward, 3S Systemtechnik and Zodiac.

Scope note that materially favors a § 103 challenge: the granted claims (1–4) are far narrower than the specification. The features the specification touts as the inventive heart — the convergent (rectangular‑triangle) shell for tangential/eddy filtration, the transverse separation wall that acts as a non‑return baffle, the rear‑offset outlet producing hydraulic drive reaction, and the pumping motor located outside the hydraulic circuit — are all described but not claimed. The claims are directed to a much more generic two‑shell remove‑in‑one‑piece filtering casing. Any "unexpected results" argument pegged to those unclaimed features therefore lacks a nexus to the claims (In re GPAC).

2. The cited prior art and what each discloses

3. Claim 1 — element mapping

Conclusion: no single reference discloses all elements (no anticipation under § 102(b)). Aqua‑Vac '178 supplies the two‑shell closure geometry and the smaller inlet port but removes the filter from the bottom; Maytronics '916 supplies one‑piece removal from the top while the unit rests normally; Jandy '532 and Lincke '074 supply the shell‑separation‑to‑dump and tool‑free‑removal concepts. Claim 1 therefore stands or falls on § 103.

4. Grounds of rejection

Ground 1 (primary): Maytronics '916 in view of Aqua‑Vac '178, further in view of Jandy '532

Rationale (KSR factors (A), (B), (F)). Maytronics and Aqua‑Vac are analogous art in the identical field and address the identical problem the '031 patent's own Background identifies: how to make the filter removable without inverting the device and without non‑return valves at the liquid inlets. Maytronics expressly teaches that a filter accessed from the top, with the debris‑laden water entering the filtering element from above, removes the need to "turn the device upside down" and "obviat[es] the need for non‑return valves." Aqua‑Vac expressly criticizes "bag"‑type filters as hard to remove/clean and teaches a rigid, multi‑part filter housing in which a first (dirty) compartment encloses debris and a removable bottom carrying a smaller inlet port closes the housing but can be separated to dump the debris.

A PHOSITA seeking to improve the top‑access Maytronics architecture with a rigid, debris‑confining, easily emptied filter would predictably look to Aqua‑Vac's two‑part housing + restricted inlet port and mount it in the top‑access chamber. Result: a first shell with peripheral filtering walls bounding a debris space; a second shell closing its front opening except for a smaller water‑inlet passage; both fitted together as an integral casing; removable in one piece through the top while the cleaner sits upright; and separable afterward to empty the debris. Every element of claim 1 is disclosed and the combination uses only known elements for their known purposes — the very definition of predictable results under KSR.

Motivation to combine, independently supported:

1. Explicit teaching in Maytronics ('916) of the top‑access/upside‑down problem, and in Aqua‑Vac ('178) of the bag‑removal/power‑consumption problem.
2. Simple substitution of one known filter‑access architecture for another (KSR factor (B)).
3. Finite, predictable solutions: at the priority date the field offered essentially two choices — bottom access (Aqua‑Vac) or top access (Maytronics); selecting the top access to preserve the cleaner's resting orientation is not an inventive leap.
4. Design incentive / market pressure: Maytronics and Aqua‑Vac both quantify the user‑friction and energy‑cost problems, supplying the "reason the inventor had the idea."

Jandy '532 is added to supply, if necessary, the express "removable pod to dump the debris" teaching for claim element (b)(v), and the latches make the dumping tool‑free.

Ground 2 (alternative): Aqua‑Vac '178 in view of Maytronics '916 (reversed primary/secondary)

Same combination, framed from the bottom‑access reference. Aqua‑Vac already shows the two‑shell closure (housing + removable bottom with smaller inlet port) and unit removal; Maytronics supplies the single missing element — removal through the top while the unit rests upright — to eliminate Aqua‑Vac's valve‑based inlet and the need to invert the machine. Motivation arises directly from Aqua‑Vac's own admission that the "bag" filter and its removal are disadvantages.

Ground 3 (alternative): Pichon '032 (US 2007/0251032 A1) in view of Maytronics '916 and Jandy '532/Lincke '074

Pichon '032 is same‑field, same‑inventor art published 2007‑11‑01 — one month before the priority date — and it teaches the very structure of the claimed "second shell": a liquid inlet conduit extending up from the base into the debris‑retaining zone, opening at a restricted free end, expressly to avoid non‑return valves. Combining that inlet‑conduit‑as‑second‑shell with Maytronics' top‑access, one‑piece removable filter and Jandy's removable dumping pod yields claim 1.

Caveat — § 103(c) / common ownership. US 2007/0251032 A1 and US 8,393,031 share inventor Pichon and assignee Zodiac Pool Care Europe. If '032 qualifies as prior art only under pre‑AIA § 102(e), a challenger must consider whether pre‑AIA § 103(c) (common ownership at the time the invention was made) disqualifies it from use in a § 103 combination. Practical consequence: Ground 3 should be treated as a fallback; Grounds 1 and 2, built on third‑party art (Maytronics, Aqua‑Vac, Jandy, Lincke), are the more robust bases for a § 103 challenge. Note also that the '031 specification itself cites US 6,013,178 and "6,409,916" as known devices, which is a binding admission that the top‑access/no‑valve problem and both access architectures were known.

Literal‑number caution

The '031 specification text cites "U.S. Pat. No. 6,409,916," whereas the "Patent Citations" list on the face of the patent lists US 6,409,916 B1. These are different numbers, and I have not been given the content of US 6,409,916 (literal). My analysis relies on US 6,409,916 B1 (Maytronics, Filter element for pool‑cleaning device, granted 2002‑06‑25), which is the reference actually appearing on the IDS/citation list and which matches the substance the specification attributes to the "flap arranged above the device … complex hydraulic circuit" device. I flag this as an unresolved identifier discrepancy rather than silently correcting it.

5. Dependent claims

Claim 2 — separation "without use of any tool."
Obvious over any of Grounds 1–3 in further view of Lincke '074 (resilient plastic clips 104 "sufficiently flexible to permit them to be manually removed") and Aqua‑Vac '178 (slide locks 35) and Maytronics '916 (beaded rim 6 snapped into recesses 32, pulled out by hand). KSR factor (C): using a known tool‑free fastener in an application where tool‑free servicing was already the stated goal. The '031 specification itself describes thumb‑pressure release of a flexible catch — i.e., the claim adds nothing beyond routine mechanical design choice.

Claim 3 — first shell = frame defining openings + filtering sheet across the openings.
Obvious. Lincke '074 discloses exactly this: a filter element of non‑woven fabric panels/pouches mounted on a perforated frame 46 whose openings are spanned by the filtering material. Aqua‑Vac '178 discloses stiff rectangular filter elements 26 seated in integral channels 28 of the filter housing — a rigid frame/sheet arrangement. Maytronics '916 discloses a filter cloth wrapped on a wire ring to impart stiffness. Combining any of these with the Grounds 1–3 casings is a predictable substitution of a known filter‑mounting technique (KSR factors (A), (C)).

Claim 4 — handle on at least one shell.
Obvious. Lincke '074 discloses a cord 102 handle "which facilitates removal of the filter element 63 from the housing." Jandy '532 discloses a graspable removable pod. Maytronics '916 discloses beaded rims for gripping. Adding a handle to a removable filter casing to improve handling is the paradigm of a predictable, results‑motivated improvement (KSR factor (C), and Ag Tek / In re Harza-type "obvious to design").

6. Anticipated counter‑arguments and why they likely fail

1. "Unexpected results" (turbulence preventing clogging; constant cleaning intervals). The specification attributes these to the transverse separation wall and the convergent shell — features that are not recited in claims 1–4. Because there is no nexus between the asserted results and the claimed subject matter, these arguments cannot rebut the prima facie case as to the granted claims. If, however, the patentee were to argue these results flow from the claimed second‑shell/inlet‑passage geometry generally, a challenger would need to show the results are inherent or expected given Pichon‑'032's and Aqua‑Vac's teachings about inlet restriction and debris confinement.
2. "Teaching away." No reference teaches away from a two‑shell, top‑access casing. Maytronics and Aqua‑Vac point toward it; Pichon‑'032 points toward eliminating valves via an inlet conduit, which is consistent. Bottom‑access (Aqua‑Vac) is a design choice, not a disparagement of top access.
3. "Non‑analogous art." All references are in swimming‑pool cleaning and filtration — the same field of endeavor. No analogous‑art defense is available.
4. Secondary considerations (long‑felt need, commercial success). The face of the patent records repeated litigation (ITC Inv. No. 337‑TA‑1326; C.D. Cal. 2:22‑cv‑05271 and 2:25‑cv‑08526; E.D. Tex. 2:25‑cv‑00582 — https://portal.unifiedpatents.com/litigation/International%20Trade%20Commission/case/337-TA-1326). Litigation alone is not evidence of nexus. A challenger should press for (a) evidence that the asserted commercial success is attributable to the claimed features rather than to the unclaimed impeller/outlet/shell geometry, and (b) objective evidence that the top‑access/no‑valve problems were long‑felt and unsolved — which is undercut by Maytronics' 2002 patent expressly solving both.

7. Bottom line

• No anticipation. No single cited reference discloses all elements of claim 1; in particular, no reference shows one‑piece top removal while the body sits upright combined with the two‑shell closure-and-dump geometry.
• Claim 1 is likely obvious under § 103 over (1) US 6,409,916 B1 (Maytronics) + US 6,013,178 (Aqua‑Vac) + US 4,768,532 (Jandy), with the alternative ordering (2) Aqua‑Vac '178 + Maytronics '916. Both are supported by express problem statements in the references, a finite/predictable set of access architectures, and simple substitution of known elements — the KSR rationales.
• Claim 1 is also likely obvious over the Pichon '032‑based Ground 3, subject to the § 103(c) common‑ownership caveat.
• Claims 2, 3, and 4 are more clearly obvious, each mapping almost element‑for‑element onto Lincke '074 (tool‑free clips, perforated frame + filtering sheet, removal cord handle), Aqua‑Vac '178, and Maytronics '916.
• Overall: on this record the strongest invalidity posture is combined‑reference § 103 on claims 1–4, with the strongest single combination being Maytronics + Aqua‑Vac (+ Jandy/Lincke for the dependent claims). A challenger should also probe what was actually argued and withdrawn during prosecution of PCT/FR2008/052339 and the corresponding EP 2 235 292 B1, since the narrow claim set (4 claims, all generic) suggests the case turned on the unclaimed shell geometry — a mismatch that generally favors an obviousness attack on the issued claims.

Confidence / limitations: I could not independently verify the internal disclosures of US 5,842,243 and EP 0 483 470 A1, and I have flagged the literal discrepancy between the specification's "U.S. Pat. No. 6,409,916" and the citation list's US 6,409,916 B1. Full confirmation of the mapping above should be completed against the complete text of US 6,013,178, US 6,409,916 B1, US 6,627,074, US 4,768,532 and US 2007/0251032 A1. This is a technical invalidity assessment, not a legal opinion.