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. 18, 1991
Filed:
Sep. 21, 1989
Alex D Colvin, Oak Park, MI (US);
Daniel J Graham, Farmington, MI (US);
Joseph C Cassatta, Taylor, MI (US);
Ford Motor Company, Dearborn, MI (US);
Abstract
A method and apparatus for measuring the electrical conductivity of a liquid comprises an electrically insulating housing through which the liquid flows, and four electrodes inserted into the path of the liquid flowing through the housing. The first and third electrodes are current electrodes and the second and fourth electrodes are voltage electrodes. An AC current is injected into the first current electrode and exits at the second current electrode, with the resulting AC voltage across the voltage electrodes being measured. The first current electrode is driven to maintain a constant value of AC voltage on the voltage electrodes while measuring the current flow in the second current electrode which is representative of the electrical conductivity of the liquid. A DC bias voltage source is provided and is coupled to each of the electrodes by a resistor and a capacitor to prevent coating or plating of the electrodes. The method and apparatus permit continuous monitoring of the absolute conductivity of a liquid.