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:
Aug. 24, 1993
Filed:
Jul. 28, 1992
Applicant:
Inventor:
James B Farr, Ann Arbor, MI (US);
Assignee:
Tecumseh Products Company, Tecumseh, MI (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04D / ;
U.S. Cl.
CPC ...
417 18 ; 417 32 ; 417 36 ;
Abstract
The present invention is a liquid level control system for selectively activating and deactivating a pump according to the liquid level indicated by capacitive sensors. Activating circuitry starts the pump motor when both upper and lower sensors indicate the presence of liquid. The pump motor is latched on by the activating circuitry and continues operation until the lower capacitive sensor indicates the absence of liquid, in which case the pump is shut off. A high frequency oscillator operates reliably over a wide range of operating conditions to maintain relatively constant charging time for the capacitive sensors.