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:
Mar. 29, 1988
Filed:
Feb. 05, 1986
Daniel F Brady, Eagan, MN (US);
Spencer B Larson, Cottage Grove, MN (US);
David B Ziegler, Eden Prairie, MN (US);
Charles B Johnson, Eagan, MN (US);
Ecolab Inc., St. Paul, MN (US);
Abstract
The invention includes a method and apparatus for controlling the concentration of wash water in a ware washing machine. A preferred ware washing machine (10) includes a reservoir (11) for holding wash water, a normally closed valve (17) for directing clean water to a dry detergent supply (13), an electrodeless conductivity cell (12) for monitoring the conductivity of the ware washing solution, and a controller for activating the normally closed valve (15) in response to the difference between the measured concentration and the actual concentration. A preferred concentration controller includes an adjustable amplifier (48) which provides an amplified concentration signal which is equal to a reference signal when the concentration of the solution is equal to the desired concentration. In addition, a preferred conductivity cell (12) includes a thermistor (46) which, in effect, increases or decreases the voltage of the signal produced by the secondary coil to remove the apparent concentration changes solely associated with changes in temperature of the washing solution.