Refrigeration – With indicator or tester – Atmospheric condensation accumulation – e.g. – frost
Patent
1996-11-06
1998-03-24
Tanner, Harry B.
Refrigeration
With indicator or tester
Atmospheric condensation accumulation, e.g., frost
62129, 62289, 340622, F25D 2102
Patent
active
057299900
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a refrigeration system having at least one defrostable cold-production device, beneath which device a drip tray provided with a drain channel is arranged.
Such a refrigeration system is known from EP 0 291 381. The drip tray is especially important in refrigeration systems which are repeatedly defrosted either periodically or in dependence on their load. The water draining off during defrosting is caught in the drip tray and discharged through the drain channel. The main application of such refrigeration systems is in refrigeration appliances, for example, refrigerators, upright freezers, chilled display cabinets or counters, and chest freezers. Such refrigeration appliances are in particular affected by the problem that the drain channel becomes blocked, for example, by food particles, bits of packaging, dust or other foreign bodies. In that case, the water is unable to drain out of the drip tray or is not able to drain out quickly enough. Sooner or later the drip tray will then overflow. Since in most cases the amount of water from defrosting is greater than the capacity of the drip tray, this leads to flooding in the refrigeration appliance, to the detriment of the products stored therein.
The drain channel therefore has to be periodically cleaned. For that purpose, in refrigerators which are closed by a door (EP 0 156 229 A2), it is known to construct the drain channel in the manner of a nozzle, that is, to give it a conical construction which converges towards a wall in such a manner that a passage of reduced cross-sectional area is created. As the door of the refrigerator is opened, a current of air is sucked through the nozzle-like opening and clears the opening of dirt and dust. This solution is not applicable, however, to larger refrigeration systems, chest freezers or similar appliances. As a rule, a door is not opened and closed here.
The invention is based on the problem of reducing the risk of flooding during defrosting.
This problem is solved in a refrigeration system of the kind mentioned in the introduction in that a liquid sensor which detects the presence of liquid at a level above the drain channel is provided in the drip tray.
When the drain channel is blocked, liquid that is produced, for example, during defrosting, will collect in the drip tray. As soon as it has reached a level or a depth at which it can be detected by the liquid sensor, the liquid sensor can give a warning signal or interrupt the defrosting. By means of the warning signal, an operator can be made aware that the drain channel is blocked. Normally, only a few manual operations are required to clean the drain channel. The warning signal can comprise, for example, illumination of a lamp.
Although a liquid sensor in a refrigeration system is known from DE 33 26 799 A1, this sensor is arranged in the drain channel itself. It is intended to interrupt the operation of the compressor as long as water is flowing out of the drip tray, that is, during the defrosting process. In this manner, it is intended that the layer of ice or frost on the refrigerating surface is fully defrosted, but the pauses during cold production are not too long. This sensor is completely unsuitable for the problem under consideration, however, because any blockage of the drain channel that may occur would be interpreted by the sensor to mean that defrosting was over and the melted water had drained off, whereas in reality the drip tray is full of water. The risk of flooding cannot be influenced in any way by this.
The liquid sensor is preferably in the form of a heatable temperature sensor. The influence of heating on the temperature is different in air to that in water or ice. Using the temperature, one can therefore determine during or after heating whether there is still water or ice in the drip tray or whether there is only air in the drip tray.
The liquid sensor preferably comprises an electrical resistor. Heating by means of current through an electrical resistor can be regulated relatively well and can be controlled wit
REFERENCES:
patent: 4037427 (1977-07-01), Kramer
patent: 4633673 (1987-01-01), Morrison et al.
patent: 4787212 (1988-11-01), Hessey
patent: 4937559 (1990-06-01), Meacham et al.
Basse Tage Stenberg
Decovski Vladimir
Danfoss A/S
Tanner Harry B.
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