Granted Patent
Utility
US 4,274,581 · App. 05/967,180
Package heat exchanger system for heating and cooling
Inventors:
Herbert G. Hays, Ralph W. Sweitzer
Patented Case
View Patent ↗
Granted: Jun 23, 1981
Filed: Dec 6, 1978
Inventors
Herbert G. Hays
Ralph W. Sweitzer
Assignee (at issue)
Raytheon Company
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.