Granted Patent
Utility
US 4,639,199 · App. 06/824,308
Two-shaft vacuum pump with internal compression
Inventors:
Heinz Frings, Hans-Peter Kabelitz, Karl-Heinz Ronthaler
Patented Case
View Patent ↗
Granted: Jan 27, 1987
Filed: Jan 30, 1986
Inventors
Heinz Frings
Hans-Peter Kabelitz
Karl-Heinz Ronthaler
Assignee (at issue)
Leybold-Heraeus GmbH
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.