Patent Publication Number: US-2020276341-A1

Title: Heat sterilizer

Description:
PRIOR ART 
     The invention relates to a heat sterilizer comprising an oven wherein a cassette can be positioned with a view to heating, which cassette may hold the instruments, materials to be sterilized. 
     Sterilization of particularly surgical instruments usually takes place in an autoclave wherein the sterilization is done by means of a steam pressure of up to 3 atm. This may impart a maximum temperature of up to 140′C to the instruments. 
     This autoclave equipment has a substantial weight and therefore it is normally only used in the form of fixedly installed autoclaves. It is a further drawback that not all supplies such as bandages etc. can stand this type of heating without being damaged or will subsequently have to be dried. 
     Moreover, sterilization by means of lamps emitting ultra-violet rays are known but in such cases the sterilization is confined to the directly irradiated surfaces. 
     Finally, sterilization by means of ozone is known which, however, is a toxic gas and accordingly requires special safety measures. 
     OBJECT OF THE INVENTION 
     It is the object of the invention to remedy these deficiencies and drawbacks and at the same time to provide a light and so mobile sterilization equipment. 
     This is achieved according to the invention by means of a cassette which can be positioned in an oven space, said cassette comprising a tray with a lid made of metal and provided with a coating on the inside, said coating comprising materials with a high emissivity. 
     In this way, it is possible to sterilize for example surgical equipment and appurtenant utilities solely by means of dry heat and as the emission through the walls of the cassette is very high, it will be possible to reach temperatures up to as high as 249° C. 
     This will reduce the heating time just as it will be possible to manufacture ovens and cassettes in the nature of small mobile units making the equipment suitable for field applications. 
     By using electrical heating elements as a heat source as mentioned in claim  2 , the provision of a high-power compact oven having an insignificant heat loss by the heat transmission is ensured. 
     By using electrical heating elements in the form of either resistance and/or induction heating elements as mentioned in claim  3 , it is possible to select an economical and practical heating of the cassette. 
     By being able to displace the heating elements as mentioned in claim  4 , partly for tight abutment on the surface of the cassette and partly away from same, the cassette may easily be inserted in and be removed from the oven after sterilization. 
     By using either a stationary power supply or a mobile accumulator-based power source as mentioned in claim  5 , mobile application of the sterilizer is ensured. 
     Finally, as mentioned in claim  6 , it is advantageous to use the sterilizer in big as well as in small surgical units. 
    
    
     
       DRAWING 
       An example of a preferred embodiment will be further described in the following with reference to the drawing wherein 
         FIG. 1  is a section through a cassette and its contents, 
         FIG. 2  is an enlarged sectional view of the wall/lid with coatings, and 
         FIG. 3  is a sectional view of an oven with an inserted cassette. 
     
    
    
     DESCRIPTION OF AN EXAMPLE OF AN EMBODIMENT 
       FIG. 1  shows an example of an embodiment of a cassette  1  comprising a tray  2  having a lid  3 . These parts are all made of metal such as stainless steel, aluminium or other metals and alloys. 
     The instruments and other objects  6 ,  7  may be placed in this cassette with a view to subsequent sterilization in an oven. 
     As shown in  FIG. 2 , which is an enlarged sectional view of the basic material  2 ,  3 , the same is provided with a coating  4  in the form of a laminate. 
     This coating consists of at least two different layered materials  9  and  10 . The materials may comprise pulverized, micronized substances having high emissivity and/or high refractory indexes. 
     Examples of such suitable substances are Ga with an index of about 4.0, GaP of about 3.0, SiC of about 2.5, TiO 2  of about 2.4 and GaN with an index of about 2.3. Morever, Carbon Black and Vantablack may be mentioned as examples of materials with a high emissivity. 
     These materials are applied in layers for forming a laminate  4  in that on the basic material  2 ,  3  there is applied a first layer  9  for example by printing, rolling or the like of a pulverized material dissolved in a binding agent where after a further layer  10  may be applied. 
     These two layers preferably have different refractions for forming an efficient internal reflection by the refraction of the heat waves between the layers. 
     Furthermore, a third layer  11  may be applied which may consist of e.g. ZnS or TiO 2 , the white colour thereof providing an attractive appearance. 
     Heating of cassette  1  with its contents  6 ,  7  takes place in an oven  12  with an oven chamber  13  as shown in  FIG. 3 . 
       FIG. 3  shows a sectional view of an oven  12  comprising an oven chamber  13 . In this chamber  13  there are in this case arranged heating elements  14 ,  15 ,  16  which may abut on the surface of the cassette with its contents  6  and  7 . 
     A heating element  16  is arranged below, four heating members  15  along the side surfaces of the cassette and an upper heating element  14  may abut on the lid  3 . 
     As indicated by arrows  8 , the heat stress will be equally directed towards the contents  6 ,  7  in the cassette. 
     To facilitate the insertion as well as the removal of the tray, some of or all heating elements are displaceable towards and away from the cassette by means of actuators  17  which may also be pivotable as indicated by arrows. 
     Either resistance or induction heating elements may be used as a power source and same may be both a fixed installation with normal line voltage or a low-voltage power source such as an accumulator-based power source may be used. 
     The result is a mobile, i.e. movable, sterilization unit which can be used e.g. in connection with field hospitals or clinics. 
     Since the oven may be manufactured to have various sizes, it will be possible to use various sizes of cassettes providing for manufacturing of relevant cassette sizes and ovens according to requirements. 
     The surface coating  4  is non-toxic and will in no way emit harmful gases so that the sterilization will comply with all requirements on sterilization of surgical equipment and the like.