SSI Technologies, LLC, v. Dongguan Zhengyang Electronic Mechanical LTD, No. 21-2345 (Fed. Cir. 2023)
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SSI alleged that DZEM infringes two of SSI’s patents that are generally directed to sensors for determining the characteristics of fluid in a container, such as a fuel tank. SSI’s commercial embodiments of the asserted patents and DZEM’s accused products are systems that determine the quality and volume of diesel exhaust fluid that is used in emission-reduction systems for diesel truck engines. DZEM asserted counterclaims for invalidity of the asserted patents and for tortious interference with prospective business relations.
The district court granted DZEM summary judgment on the infringement claims and dismissed DZEM’s invalidity counterclaims, granting SSI summary judgment on the tortious interference counterclaim. The Federal Circuit vacated in part, reversing the district court’s construction of the term “filter” as used in the 038 patent. The term is properly construed to mean “a device containing openings through which liquid is passed that blocks and separates out matter, such as air bubbles.” On remand, SSI will not be precluded from arguing that DZEM’s accused sensors infringe under the doctrine of equivalents. The court affirmed summary judgment with respect to the 153 patent and DZEM’s counterclaim for tortious interference.
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