Invalidity dossier
US 2600236
Muffler with a plurality of passages
Current assignee: ESTHER LARSEN
Added 9/24/2026, 1:27:13 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US 2600236 — "Muffler with a plurality of passages"
Bibliographic data (from source): Inventor Stephen J. Gibel; original assignee/current assignee listed as Esther Larsen; application US60356A; filed and priority date 1948-11-16; granted and published 1952-06-10; anticipated expiration 1969-06-10; status "Expired – Lifetime." Classifications include F01N1/08, F01N1/10, F01N1/16, F01N1/22, F01N2450/16, F01N2450/24.
Purpose: To silence noise in a pressure-fluid exhaust, such as exhaust from a compressed-air-operated power cylinder or tool, by expanding the exhaust fluid and dissipating its energy.
Plain-language scope (as described in the excerpt): A housing forms a main (silencing/expansion) chamber. An end member has an inlet chamber and a group of passages (six shown) that direct exhaust streams into the main chamber at inclined angles. The chamber's wall is resilient and porous, formed of felted fibrous material (e.g., felted vegetable or animal fibers/hair, optionally with a binder), so fluid exits to atmosphere by diffused flow through the wall. Streams impinge angularly on the resilient wall, reverberating within the chamber; multiple streams conflict/oppose each other so energy of one dissipates against another. A denser inner surface layer (e.g., shellac, varnish, lacquer, synthetic resin, oil, grease, wax, or asphalt; about 1/32 inch thick) increases reflection. Alternative porous bodies are mentioned: granular material (carbon, charcoal, ground cinders), cork, pulp/cellulose, ceramic, or porous plaster/cement. Embodiments include turbulating means producing swirling streams and minute resilient diaphragms; Figures 1–9 depict sections, flow diagrams, and a modified form. End members may be metal or plastic, joined by a central axial screw.
Source: https://patents.google.com/patent/US2600236/en
What the excerpt does not establish: The full claim language, complete description, and all drawing details (text is excerpted/OCR-degraded, with truncated passages); any legal conclusions on validity, enforceability, or claim scope; prior-art comparisons; litigation or ownership transfers; and whether listed assignee/status data are accurate (the source itself disclaims legal analysis).
Generated 10/1/2026, 9:31:24 PM
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Litigation summary
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Proceedings on file (0)
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No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.