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Federal Circuit Affirms PTAB’s Finding Of Unpatentability Of Patent Relating To Ultrasonic Flow Meters And Housings, Involving Product-By-Process Claim Element
08/23/2022On August 12, 2022, the U.S. Court of Appeals for the Federal Circuit (“CAFC”) affirmed the decision of the Patent Trial and Appeal Board (“PTAB”), which found unpatentable the challenged claims of a patent relating to housings for ultrasonic flow meters. Kamstrup A/S v. Axioma Metering UAB, __ F.4th __ (Fed. Cir. Aug. 12, 2022).
Kamstrup A/S (“Kamstrup”) owns U.S. Patent No. 8,806,957 (the “’957 patent”), which is directed to an ultrasonic flow meter housing that consists of a monolithic polymer structure, which is cast in one piece. In September 2019, Axioma Metering UAB (“Axioma”) petitioned for inter partes review of all of the claims of the ’957 patent. The PTAB subsequently found the challenged claims unpatentable as anticipated or obvious. In doing so, the PTAB construed various claim elements, including (i) “cast in one piece” as a product-by-process claim limitation, and (ii) “cavity separated from the flow tube” as requiring that the interior of the flow tube be separated from the surrounding cavity by a shared wall. Based on these constructions, the PTAB found that a prior art reference “Ueki” anticipates several of the asserted claims, and that the combination of Ueki with two other references “Elson” and “Barker” render obvious the other challenged claims.
Kamstrup made several arguments on appeal. First, Kamstrup argued that the PTAB erred in construing “cast in one piece” as a product-by-process claim element that did not carry patentable weight. Second, Kamstrup argued that the PTAB erred in construing “cavity separated from the flow tube” because it should have been construed to exclude a cavity that surrounds the flow tube, and that it erred with respect to constructions of certain claim limitations of dependent claim 6. Third, Kamstrup made various arguments relating to patentability, including that Elson and Barker are not analogous art.
A product-by-process claim is one in which a product is claimed, at least in part, by the process by which it is made. This enables a patent applicant to claim an otherwise patentable product that resists definition by other than the process by which it is made. When analyzing the validity of a product-by-process claim, it is relevant to determine whether the process itself imparts structural and functional differences that distinguish the claimed product from the prior art. If so, then those differences are relevant as evidence of no anticipation although they are not explicitly part of the claim.
On appeal, Kamstrup argued both that (i) the PTAB erred in concluding that “cast in one piece” is a product-by-process claim element and (ii) the product-by-process claim element did not impart patentable weight to the claims. With respect to the former, the CAFC found that the claim language itself confirms that this is a product-by-process limitation because, on its face, the claim is describing the structure being cast in a particular way. With respect to the latter, the CAFC rejected Kamstrup’s argument that various structures cannot be cast in a “single mold” using conventional die cast injection molding technologies, because (i) Kamstrup had not identified functional and structural differences between a structure “cast in one piece” and a structure manufactured using another method, and (ii) Kamstrup alleged functional and structural differences that were irrelevant because they were detached from the claim. Specifically, the claims state that the structure should be cast in “one piece,” not cast in one mold, as Kamstrup argued.
With respect to the Kamstrup’s second argument on appeal, the CAFC rejected Kamstrup’s contentions that (i) the plain meaning of “separated from” does not encompass “surrounding,” (ii) no embodiment discloses the cavity completely surrounding the flow tube, and (iii) the claim limitation would not be enabled if it included a cavity that surrounds the flow tube. The CAFC explained that (i) Kamstrup improperly sought to read in a negative limitation that is at odds with the claim language, (ii) while no embodiment explicitly discloses such a cavity, the specification did not limit the claim in the manner Kamstrup alleged, and (iii) Kamstrup’s argument—that a design where the cavity surrounds the flow tube would require the flow tube to be manufactured separately from the housing—was irrelevant because the CAFC had already found “being cast in one piece” to not carry patentable weight, and therefore not a basis for limiting “cavity separated from the flow tube.” The CAFC also rejected Kamstrup’s various contentions with respect to dependent claim 6 because they were based on an improper attempt to read limitations into the claim.
With respect to Kamstrup’s third argument on appeal, the CAFC found that the PTAB did not err in finding Elson and Baker to be analogous art because substantial evidence supported the PTAB’s finding that those two references are directed to sensing or measuring fluid flow and fluid flow characteristics, such as temperature, notwithstanding that the references relate to medical devices for thermodilution (and not specifically ultrasonic flow meters). The CAFC rejected the remainder of Kamstrup’s patentability arguments because they were premised on the claim constructions that the CAFC affirmed.
