Peter A. Hammerquist v. Clarke's Sheet Metal, Inc.
Opinion
Opinion
Goodwin, J.
Clarke’s Sheet Metal, Inc. appeals from a judgment, following a jury verdict, that held claims 1, 2 and 3 of Hammerquist’s U.S. Patent No. 3,854,910 to be valid and willfully infringed.
The Hammerquist patent claims described an apparatus for collecting dust from industrial plants. The apparatus is a combination of devices: (1) a dust collector for heavy dust particles known as a “centrifugal dust collector” (often called a cyclone); and (2) a dust filtering device for smaller particles (often called a baghouse) composed of a chamber within which is housed a circular array of pervious fabric bags for collecting dust. The system operates by filtering air from the cyclone through the baghouse. It is cleaned by reverse air flowing from the baghouse to the cyclone.
Hammerquist first constructed his bag-house filter in August 1972 (the Aero-Vac filter). He installed it by mounting it directly on top of the cyclone; i. e., “hat-mounted.” On the basis of this invention he applied for and received a patent. At a later date, Hammerquist dismounted the baghouse and cyclone placing them side-by-side with a pipe connection. This second model, INV Aero-Vac was sold but not patented.