Granted Patent
Utility
US 4,643,217 · App. 06/737,521
Automatic valve for use with pool cleaning devices
Inventor:
Herman E. Frentzel
Patented Case
View Patent ↗
Granted: Feb 17, 1987
Filed: May 24, 1985
Inventor
Herman E. Frentzel
Assignee (at issue)
Arneson Products, Inc.
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.