Automatic refrigeration apparatus provided with a sterilized storage compartment

Abstract: An automatic refrigerator includes a sterilized stora­ ge compartment (3), normally kept at a food storage temperature, in which blowing means (16) provide a forced ventilation. A germicide lamp (12), capable of generating ultraviolet radiations, is located in the flow path of said forced ventilation and is associated with shielding means (13) protecting the storage com­ partment (3,11) from said radiations.

Description: The invention refers to an automatic refrigeration apparatus including a sterilized storage compartment defined by plastic material. It is common knowledge that storage conditions having a temperature between approximately 0 o C and 10 o C normally favor development of certain moulds, yeasts and bacterial spores within a storage room, which affect the good preservability of food or other items. As is known, a most efficient way to eliminate moulds, yeasts and bacterial spores consists in subjecting these micro-organisims to the action of ultraviolet radiations, as may be generated for example by U.V. lamps currently available on the market. In US-A-2 906 104, a refrigeration apparatus is disclosed comprising a U.V. radiation lamp disposed in a housing having an opening in which a rotating disc is disposed, said disc having an aperture offset from the center of the disc, so that upon rotation of the disc a radiation beam is swept over the goods comprised in the compartment. The housing also comprises openings disposed in an airflow path established in the compartment of the refrigerator so that irradiation of air-borne bacteria may be effected as well. On the other hand, the use of such U.V. lamps for irradiating the inner space of a refrigerating apparatus is not immediately feasible, as it is known that ultraviolet radiation produces in the long run devastating effects on both the appearance and the structure of the materials - mainly plastics - of which most components of the refrigerator's storage compartment are made. From FR-A-1 141 573, a refrigeration apparatus for foodstuffs is known comprising means for circulating air from the refrigeration compartment in a closed circuit in which a U.V. lamp is disposed for irradiating said circulating air. Any structural features are not disclosed in this document. It is the object of the invention to provide a refrigeration apparatus of the aforementioned kind which is adapted to ensure an effective sterilization of the storage compartment, while excluding all undesired impairing byeffects on the materials forming said storage compartment. This object is attained by the features of claim 1. The invention will be further described by way of non-limiting example with reference to the accompanying drawings in which: Figure 1 is a basic schematic view of a preferred embodiment of the invention, and Figure 2 is a wiring diagram showing the control system for a refrigerator according to Fig. 1. Referring in particular to figure 1, the refrigeration apparatus according to this invention mainly includes a storage compartment 3, which is normally defined by a plastic liner 11, and to which access is gained through a door 4. The storage compartment is cooled by an evaporator 5, which is part of a conventional-type refrigerating circuit, such as for example a circuit including also a compressor 6, a condenser 7 and a throttling device 8. In a per sè known manner, a thermostatic temperature control device 9 is actuated by at least one probe 10, which is intended to detect the temperature of the evaporator 5 so as to most suitably initiate and terminate the operation cycles of the compressor 6. The control device 9 can of course be also actuated by a probe (not shown for simplicity sake) intended for detecting the temperature prevailing inside the storage compartment 3. In all cases, however, the refrigerating circuit will be controlled so as to normally maintain the storage compartment 3 at a refrigeration temperature ranging from approx. 0°C to 10°C. As it is known, such temperature conditions, when combined with normally prevailing humidity conditions, can give rise to the development of moulds, yeasts and bacterial spores inside the storage compartment 3. To eliminate these micro-organisms, the refrigerator is provided with germicide means 12, which are preferably located in a place inside the storage compartment 3 and are apt to generate ultraviolet radiations. In particular, said germicide means 12 can consist of at least one UV lamp capable of generating C - type ultraviolet radiations, i.e. radiations having a wavelength equal to 2537 Å. For example, a lamp that could be used for this application is the TUV 6W lamp marketed by Philips. However, as already mentioned, this is contrary to a technical prejudice, since ultraviolet radiations can alter the appearance and the structure of the walls and other components of the storage compartment 3, which are made of plastics. According to a feature of this invention, said particular disadvantage is substantially eliminated by having the lamp 12 suitably associated with appropriate shielding means 13, which are capable of preventing the walls of the storage compartment 3 from being exposed to ultraviolet radiations. In a preferred embodiment, said shielding means 13 include a housing designed to accomodate the UV lamp and preferably made of reflecting metal, such as aluminium. The housing 13 is provided with inlet openings 14 and outlet openings 15 for an air flow which is circulated inside the storage compartment 3 by a motor-driven fan 16, or the like, which is also located inside the housing 13. Said openings 14 and 15 are sized and shaped in a most appropriate way, so as to keep the leakage of ultraviolet radiations from the housing 13 to a minimum. The motor 17 of the fan 16 and the lamp 12 are arranged so as to be operated at the same time by a control output 18 of the thermostatic device 9, this being preferably made to occur during the automatic defrosting periods of the evaporator 5 which are determined in a per sè known way by the refrigerating circuit 5-10. To this aim, as it is shown in fig. 2, the thermostatic device 9 includes a changeover switch 90 having two switching positions based on the temperature detected by the probe 10, in which positions it is arranged to connect to the terminals 19 of a power supply source either the compressor 6 or the parallel-connection of the lamp 12 and the motor 17 of the fan 16. In a preferred embodiment, a heater 20 for defrosting the evaporator 5 would also be connected in parallel to the lamp 12 and the motor 17. The operation of the refrigerator according to this invention is apparent: when a relatively high temperature is detected by the probe 10, the thermostatic device 9, 90 will switch on the compressor 6, whereas both the lamp 12 and the fan 16 will be switched off. When a relatively low temperature is detected by the probe 10, the compressor 6 will be switched off by the thermostatic device 9, 90 which will on the other hand switch on both the lamp 12 and the motor 17 of the fan 16, as well as - if provided - the defrost heater 20. Under these conditions the refrigerator goes therefore through a defrosting operation of the evaporator 5, during which the fan 16 circulates inside the storage compartment 3 a forced-air flow that - being conveyed to pass through the housing 13 of the lamp 12 - is sterilized by the UV lamp 12 and, as a consequence, will itself sterilize the storage compartment 3 where it is circulated. As it was also experimentally found, such a periodically occurring action of ultraviolet radiation causes moulds, yeasts and bacterial spores inside the storage compartment 3 to be effectively eliminated, while the storage compartment 3 itself is not exposed to the radiations at all. It should further be noticed that the operation of the fan 16 only during the defrost periods prevents the storage compartment environment from undesirably drying up in a too severe way. Quite on the contrary, the forced air circulation during the defrost cycles of the evaporator 5 allows the humidity that was previously condensed and frosted on the evaporator surface to be advantageously recovered into the storage compartment space. In order to enhance its effectiveness in this sense, the air flow circulated by the fan 16 can be suitably directed towards the evaporator 5 by means of a baffle 21 or similar arrangement. In order to limit the periods of operation of the UV lamp 12 and the fan 16, these could advantageously be only switched on during a portion of each defrost period. This could for example be implemented by connecting the lamp 12 and the motor 17 to the changeover switch 90 (Fig. 2) through a timing device 22 (shown by the dashed line). Said device 22 may be made to include a timer switch of a per sè known type, which could for example be controlled by a RC-device having a time constant which is shorter than the average duration of a defrost cycle of the refrigerator.

Claims: An automatic refrigeration apparatus, including a sterilized storage compartment (3) defined by plastic material and normally kept at a food storage temperature, air circulation means (13 to 17) defining a flow path of air in said compartment (3) and comprising blowing means (16, 17) capable of providing a forced ventilation inside said compartment (3), germicide means (12) capable of generating ultraviolet radiations and fixedly disposed in a housing (13) having inlet and outlet air openings (14, 15) in said air flow path, and arranged to substantially prevent leakage of ultraviolet radiation from the housing (13) and concurrently enable said air flow to extend through said housing (13) to be irradiated therein, and shielding means (13, 14, 15) made of metal and arranged over said germicide means (12) for preventing an irradiation of said compartment (3) by said germicide means (12), said shielding means (13, 14, 15) consisting of said housing (13) which is arranged to totally prevent said compartment (3) from being exposed to ultraviolet radiations.

Inventors: FELTRIN FLAVIO, FELTRIN, FLAVIO
Applicants: ZANUSSI A SPA INDUSTRIE, INDUSTRIE ZANUSSI S.P.A.
Application year: 1988
Main classification: F25D17
IPC codes: F25D17, A61L9