Refrigeration – Automatic control – Preventing – removing or handling atmospheric condensate
Patent
1982-08-27
1985-07-30
Tanner, Harry B.
Refrigeration
Automatic control
Preventing, removing or handling atmospheric condensate
62140, 62155, F25D 2102, F25D 2106
Patent
active
045313768
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an evaporating coil defrost control for various types of refrigeration apparatus and more particularly to an automatic defrost system for refrigeration apparatus that will provide a positive termination control for the defrost cycle. In addition, the invention provides a low cost means for interfacing with present solid state defrost initiation devices.
The invention provides an inherent positive and "fail-safe" means for terminating the defrost cycle that is independent of the means for initiating the defrost cycle and meets all of the present safety requirements of the refrigeration industry.
BACKGROUND ART
The representative prior art for refrigeration defrost control is disclosed in the following U.S. Patents: U.S. Pat. Nos. 3,899,895 (Blanton et al); 3,839,878 (Tilmanis); 3,826,103 (Grover); 3,759,049 (Bell et al); 3,726,105 (Auracher); 3,626,707 (Bauknecht et al); 3,525,222 (Schuller); 3,518,841 (West, Jr.); 3,492,832 (Davis et al); 3,436,929 (Harbour); 3,373,575 (Nelson); 3,228,204 (Matthies); 3,203,195 (Armentrout); 3,174,297 (Kuhn et al); 3,138,006 (Moorman et al); 3,134,238 (Matthies); 3,105,364 (O'Connell); 3,055,188 (Syfert); 2,949,017 (Swanson); 2,907,180 (Mann); 2,866,323 (Candor); and 2,765,630 (Shaw).
The patent to Moorman, et al (U.S. Pat. No. 3,138,006) discloses a defrost control arrangement for a two compartment refrigerator, one compartment generally operating below-freezing and the other operating at above-freezing temperatures. Warmer humid air is drawn from the above-freezing compartment to the below-freezing compartment and directed over the evaporator to cool and remove moisture from the warm humid air. The cooled air is directed downwardly by a fan to the above-freezing compartment through a passageway, the airflow through which is controlled by a thermostatically controlled air valve. The defrost control includes a snap-acting, double-throw, bimetal, thermostatic switch that is mounted upon the edges of the fins of the evaporator at the point where the warm humid air from the above-freezing compartment enters the evaporator chamber and is responsive to the temperature of the warmer air flowing from the above-freezing compartment and the temperature of the evaporator surface.
The switch has first and second contacts which are alternately energized upon a rise in temperature to about 55.degree. F. and to a fall in temperature to about 28.degree. F. when the switch has frost formed about its outer surface. The refrigerating system is connected to the energy supply upon the rise in temperature of the switch to 55.degree. F. and remains connected until the temperature of the switch falls to 28.degree. F. and is frosted. When the temperature falls to 28.degree. F. the defrost system is connected to the energy supply for defrosting the evaporator. When the thermostat switch is free of frost, it is warmed by the relatively warm air from the above-freezing compartment, thus preventing the thermostat from falling to the low defrost temperature. After frost accumulates on the thermostat and the evaporator, the rate of air flow is reduced and the thermostat is shielded from the warmer air from the above-freezing compartment by the frost covering on the thermostat. This shielding action by the frost lowers the temperature of the thermostat. To prevent unnecessary defrosting by the thermostat because of temperature variations, a small electric heater is provided that is in heat transfer with the thermostat and normally energized to compensate for such temperature variations.
When the above-freezing compartment rises to an abnormally high temperature, the air valve will move to an abnormally wide-open position and opens a switch contact in series with the thermostat heater, permitting the thermostat to cool if the thermostat has sufficiently frosted over to lower the temperature below 28.degree. F. The thermostat will snap to the defrost position and energizes a defrost heater to melt the frost from the evaporator. The thermostat heater is also con
REFERENCES:
patent: 2849617 (1958-08-01), Karasek
patent: 2866900 (1958-12-01), Busignies et al.
patent: 3120108 (1964-02-01), Pansing
patent: 3138006 (1964-06-01), Moorman et al.
patent: 3188828 (1965-06-01), Wayne
patent: 3585483 (1971-06-01), Skirvin
patent: 3588496 (1971-06-01), Snowman
patent: 3737731 (1973-06-01), Zeewy
patent: 3946286 (1976-03-01), Kinnunen et al.
patent: 3961495 (1976-06-01), Beauvent et al.
patent: 4109481 (1978-08-01), Peek
patent: 4299095 (1981-11-01), Cassarino
Optical Methods in Ultracontrifugation, Electrophoresis and Diffusion, Lloyd, Jul. 1972.
LandOfFree
Refrigerator defrost control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Refrigerator defrost control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Refrigerator defrost control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2366455