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. 03, 1993
Filed:
Sep. 05, 1991
James B Farr, Ann Arbor, MI (US);
Tecumseh Products Company, Tecumseh, MI (US);
Abstract
The present invention is a cold control for refrigerators. The cold control circuit includes temperature sensitive resistances disposed within the cold box portion of the refrigerator. The cold control circuit senses the temperature of the cold box portion by a NTC thermistor which is disposed in the cold box portion and connected to the control circuit. When the temperature rises above the turn-on set point, the NTC thermistor has a relatively small resistance and activates a transistor. The transistor is connected to a latching circuit which maintains activation of the refrigerator until the thermistor falls below the turn-off point. Another solid state switch of the control circuit activates the refrigerator compressor, such as a transistor turning on an inverter in a DC powered refrigerator and a triac directly supplying current in an AC powered refrigerator. For battery powered refrigerators, the cold control includes a clipping circuit to prevent false activation or de-activation of the inverter caused by ripple voltages. The present invention provides the reliability of a solid state temperature sensor while avoiding the expense of a microprocessor driven system.