Granted Patent
Utility
US 4,475,335 · App. 06/463,504
Free piston heat engines
Inventor:
Gordon Davey
Patented Case
View Patent ↗
Granted: Oct 9, 1984
Filed: Feb 3, 1983
Inventor
Gordon Davey
Assignee (at issue)
NATIONAL RESEARCH DEVELOPMENT CORPORATION
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.