Refrigeration – Processes – Deodorizing – antisepticizing or providing special atmosphere
Reexamination Certificate
1998-11-04
2001-05-29
Tapolcai, William E. (Department: 3744)
Refrigeration
Processes
Deodorizing, antisepticizing or providing special atmosphere
C062S264000
Reexamination Certificate
active
06237350
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a refrigerated display case, as well as a method for sainitizing such display cases. In refrigerated display cases, in particular the evaporating apparatus used to cool a circulating airflow causes sanitary problems. Microorganism that attach themselves to the cooling surfaces of an evaporating apparatus, e.g. bacteria, fungi or the like (in the following briefly referred to as “germs”), can multiply only to a negligible degree, owing to the low temperatures that prevail during the operation of the evaporating apparatus. However, the defrosting phases present a problem. Following a specific operating time, evaporating apparatuses generally become covered with ice. A sheet of ice on the cooling surfaces prevents the heat exchange or the cooling ability of the evaporating apparatus. For the defrosting, the supply of cooling agent to the evaporating apparatus is interrupted. In other words, a compressor that is generally arranged outside of the refrigerated display case or a refrigeration device containing a compressor is shut down, thereby allowing the ice that has formed on the cooling surfaces of the evaporating apparatus to melt. The danger during this process is that the number of germs in the condensation water will increase with increasing temperatures. Since the condensation water can low into places in the refrigerated display case that are not accessible or hard to access, every defrosting operation represents a sanitary risk for refrigerated display cases used until now.
SUMMARY OF THE INVENTION
It is the object of the invention to propose a refrigerated display case and a method for sanitizing a display case, which are improved from a sanitary point of view. This object is solved with respect to the refrigerated display case and to the sanitizing. A refrigerated display case according to the invention comprises on the one hand a defrosting device using hot gas for defrosting the evaporating apparatus and, on the other hand, a UV radiation source for treating the evaporating apparatus directly with the UV radiation during this process, the evaporating apparatus is admitted directly with UV radiation during the defrosting operation with hot gas. The use of a hot-gas defrosting method will first of all reduce the time required for defrosting the evaporating apparatus to approximately 15 minutes. A significant increase in the harmful germs at the evaporating apparatus is prevented simply because of the short defrosting time. Admitting the display case at the same time with UV radiation will not only prevent the additional reproduction of germs on the cooling surfaces or in the defrosting water, but will kill existing germs as well. Thus, in addition to the cooling surfaces of the evaporating apparatus, the defrosting water dripping down is also essentially germ-free. In this way, germs are prevented from reaching lower and hard to access areas of the refrigerated display case with the condensation water. The suggested defrosting method is so effective from a sanitary point of view that a sterilization of the circulating airflow during the normal operation of the display case can be omitted. It is furthermore advantageous that energy can be saved because the UV radiation source or the UV sterilizing tube is used for a short time only. During the relatively short defrosting phase, the temperature of the goods changes only insignificantly, that is to say by only 0.5 to 1° C. Owing to the proposed hot-gas defrosting, the goods therefore do not have to be removed.
A preferred hot-gas defrosting device provides that a hot-gas line with controllable shut-off valve is connected on the input side with the evaporating apparatus and on the output side with the compressor for the cooling apparatus. The cooling apparatus is preferably arranged at a distance to the refrigerated display case. For the hot-gas defrosting, it is only necessary to open the shut-off valve. The compressor pumps the cooling agent that is heated up during the compression directly into the evaporating apparatus. The hot-gas line may be a diathermal pipe, in particular a pipe made of copper. It has turned out that the defrosting of the evaporating apparatus takes place during a relatively short period of time, even if the “hot gas” supplied to the evaporating apparatus or the cooling agent is approximately at room temperature. An expensive insulation of the hot gas line can therefore be omitted. It may even be useful if the outside surface of the hot-gas pipe is enlarged by structures akin to cooling fins at suitable locations where relatively high environmental temperatures occur, so as to increase the heat absorption from the environment (claim
4
).
The invention can provide that the evaporating apparatus is arranged in a region that is spatially separate from the goods area and the tub area. This separation occurs preferably with the aid of separating walls. Thus, the water flowing out of the evaporating apparatus during the defrosting operation cannot reach the tub area unchecked, which is surrounded by the display case wall. The evaporating apparatus furthermore can be accessed easily for regularly scheduled, thorough cleaning operations, owing to the fact that the air filter covering the exhaust opening can be removed. If, the blower is furthermore arranged in the ascent shaft between evaporating apparatus and air filter, this blower can also be cleaned easily from the outside or via the exhaust opening. This is also made easier by the fact that it can be tilted out. An arrangement of the blower in which it is located in the region where the UV sterilizing tube is effective, will prevent the formation of germs in the blower region or existing germs will be killed. The UV radiation source admits the evaporating apparatus as well as the blower if it is arranged between the blower and the evaperating apparatus.
The sanitary conditions of the display case are improved considerably in that a spraying device is arranged in the tub region, which sprays at least the tub bottom with cleaning fluid. The tub region in general can be cleaned with such a device. In connection with a defrosting of the evaporating apparatus, this measure results in a complete removal of the condensation water flowing from the evaporating apparatus to the tub bottom. This prevents condensation water from collecting in inaccessible spots, thereby serving as location where germs can breed. The spraying device preferably comprises a spray head that is arranged on the tub bottom. The discharge openings or spray openings of the spray head in this case are preferably aligned in such a way that for the most part the bottom region rather than the underside of the goods platform is admitted with cleaning fluid. It is advantageous if the spraying device is supplied directly from the supply of potable water. A separate spraying device is proposed for additionally spraying a cleaning fluid into the tub region or onto the tub bottom to increase the cleaning effect of the water. The spraying device can also be supplied from a container holding a cleaning fluid that already contains a cleaning agent, e.g. with the aid of a pump. The spray device is particularly effective if, the tub region contains as few built-in parts as possible.
Another advantageous embodiment of the display case according to the invention provides for a control device, which makes it possible to control the hot-gas defrosting device, the spray device, the blower as well as the UV sterilizing tube. In that case, the defrosting operations or the cleaning operations are performed automatically, without requiring any operating personnel. The control device is preferably connected to an automatic control device for cooling the refrigerated display case. The cleaning or defrosting operations are preferably carried out during predetermined time intervals that can be adjusted on the control device.
REFERENCES:
patent: 3561230 (1971-02-01), Gatton et al.
patent: 4315414 (1982-02-01), Ibrahim
patent: 4416120 (1983-11-01), Yono et al.
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