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:
Oct. 13, 1998
Filed:
Jul. 23, 1997
Allan E Witt, Brown Deer, WI (US);
Hatco Corporation, Milwaukee, WI (US);
Abstract
A method and apparatus for controlling the speed at which an AC electric motor drives a conveyor to move food products through a conveyor oven are disclosed herein. The oven includes a housing, electric heating elements mounted within the housing, and a conveyor to move food-carrying baskets adjacent the heating elements. A motor controlled by a speed control circuit moves the conveyor. The speed control circuit includes a rectifier to provide rectified current to the motor, a shunt circuit to bypass the rectifier with a rheostat to set the conveyor speed, a thermostat to monitor oven temperature, and a speed-reducing circuit to introduce additional resistance into the shunt circuit when the oven temperature drops. The thermostat also controls additional heating elements to provide additional heat during high load conditions. If an increase in oven load causes a drop in temperature, the additional heating elements are turned on and the conveyor speed is reduced as the additional resistance is introduced into the shunt circuit. The slower speed gives additional heating time at low oven temperatures. The method and apparatus disclosed herein may also be used with conveyor ovens for non-food products.