Granted Patent
Utility
US 4,306,526 · App. 05/910,581
Internal combustion engine
Inventors:
Fred S. Schaub, Melvin J. Helmich, Robert L. Hubbard, Melvin C. Hoagland
Patented Case
View Patent ↗
Granted: Dec 22, 1981
Filed: May 30, 1978
Inventors
Fred S. Schaub
Melvin J. Helmich
Robert L. Hubbard
Melvin C. Hoagland
Assignee (at issue)
Cooper Industries Holdings
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.