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:
Feb. 16, 1982
Filed:
Feb. 06, 1980
James A Purdy, Sylvania, OH (US);
Carl K Dudley, Petersburg, MI (US);
Eltra Corporation, Toledo, OH (US);
Abstract
A wear-indicating brush and warning circuit is adapted to convey an indication that a dynamoelectric machine is in need of maintenance before the brush wears to the point that a rotor contact surface is damaged by contact with electrical connections to the brush. A brush (10) having current carrying pigtail leads (16) embedded therein includes a wear-detecting wire (20) embedded in the brush a short distance (A) beyond the lowest extent of the pigtail leads (16). The wire (20) is insulated over its periphery, including its tip (24), the insulation (26) being abraded by contact with the rotor contact surface (50), so that the wire (20) senses the voltage present thereon. Non-latching warning circuits (66, 66a), with and without the use of an isolating resistor within the dynamoelectric machine to permit the use of a single wire between the machine and the warning circuit to provide a brush wear indication. Also disclosed is a warning circuit for indicating that an input is electrically connected to a voltage, for indicating that a line (20) has contacted a rotor contact surface. The voltage sense may be negative or positive, over a wide range, so that the positioning and number of brushes (10) is irrelevant. The circuit (92) includes an oscillating voltage source (122) and comparison circuits (124, 126, 128) giving a warning indication when an input line is connected to a voltage and is unable to follow the oscillating voltage.