Granted Patent
Utility
US 4,325,331 · App. 06/180,135
Dual-expansion internal combustion cycle and engine
Inventor:
Frederick L. Erickson
Patented Case
View Patent ↗
Granted: Apr 20, 1982
Filed: Aug 21, 1980
Inventor
Frederick L. Erickson
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.