The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 01, 1993
Filed:
Nov. 15, 1991
James L Greene, Kansas City, MO (US);
The Marley Company, Mission Woods, KS (US);
Abstract
A control circuit for a sump pump or other pump that controls the liquid level in a vessel. The liquid is maintained between upper and lower levels defined by probes in the vessel. The probes are associated with comparators and connect with one comparator input. The upper limit comparator connects with the gate of an SCR which supplies current to the lower limit comparator and also to a relay which controls the on/off condition of the pump. The output of the lower limit comparator controls a switching transistor which is arranged in a series circuit with the SCR and relay coil. Once the SCR is conductive, it is latched in the conductive state until the transistor is made nonconductive by the lower limit comparator. In a sump pump application, latching of the SCR allows the pump to remain activated after the liquid level is reduced below the upper probe.