Patent Publication Number: US-5422460-A

Title: Glass ceramic cooking hob with a reflecting surface arranged in a position corresponding with a light and/or heat generator, in particular a halogen lamp cooled by air circulation

Description:
DESCRIPTION 
     This invention relates to a glass ceramic cooktop including a free surface on which containers containing food to be prepared are placed, below said surface there being provided at least one light heat generator, such as a halogen lamp, at which there is positioned an element reflecting the light heat and having at least one face facing the generator or halogen lamp and an opposing face facing an external environment. 
     BACKGROUND OF THE INVENTION 
     The reflecting element is generally formed of aluminum because this material has considerable reflecting properties. This element produces optimum direction of the lamp-generated light rays towards the cooktop, on the surface of which the container is placed, so increasing the heat transmitted to this latter. In this manner the efficiency of the cooktop is optimized. However, the quantity of heat energy which can be fed to the container is limited by the reflecting element itself, which is generally the thermally weakest member of the glass ceramic cooktop. 
     SUMMARY OF THE INVENTION 
     An object of the present is to provide a invention cooktop in which the reflecting element is more protected against the heat emitted by the light heat generator. 
     A Further object is to provide a cooktop of the stated type which is thermally reinforced, is of low cost and is of simple construction. 
     A further object is to provide a cooktop in which the reflecting element is always at a temperature lower than that at which it could suffer mechanical weakening. 
     These and further objects which will be apparent to the expert of the art are attained by a glass ceramic cooktop of the aforesaid type, characterised in that that face of the reflecting element facing the external environment is exposed to an air flow generated by a cooling member positioned below the reflecting element, said air flow removing the heat stored by the reflecting element during the operation of said generator or halogen lamp, so cooling it. 
    
    
     DESCRIPTION OF THE DRAWING 
     The present utility model will be more apparent from the accompanying drawing, which is provided by way of non-limiting example and in which: 
     FIG. 1 is a cross-section through a cooktop constructed in accordance with the invention; 
     FIG. 2 is a perspective view showing the use of the cooktop of the invention built into an item of furniture, such as a kitchen unit; and 
     FIG. 3 is a cross-section through a modified embodiment of a cooktop according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to said figures, a glass ceramic cooktop is indicated overall by 1. A a surface 2 supports in contacting relationship usual containers 3 (only one is shown in FIG. 1) containing food 4 to be subjected to preparation. Several heating elements 5 are associated with the cooktop 1, they being positioned below the cooktop. 
     In the example shown in the figures, the elements 5 are halogen lamps powered in any known manner and of suitable (known) shape to heat the containers 3 on the hob 1 by the heat generated during their operation. 
     In correspondence with and below the lamps 5 there is provided a known reflecting element 10 arranged to suitably direct the light and heat rays 11 generated by said lamps towards the (upperly positioned) cooktop 1. 
     In particular, the 10 is constructed of aluminum and comprises a series of concavities and convexities 12 and 13 (with reference to the lamps), the concavities being positioned in correspondence with and below the lamps 5. 
     By this configuration the reflection element 10 directs the rays 11 substantially perpendicularly onto the cooktop 1, thus increasing the heating effect of the rays on the cooktop. 
     The aluminum reflecting element 10 has a face 15 facing the lamps 5 and a face 16 facing an external environment, such as a compartment 17 of a usual kitchen furniture unit 18. 
     The face 16 comprises at least one portion 20 of high heat transfer coefficient, to improve and increase the cooling of the reflecting elements 10. 
     Specifically, in one embodiment shown in FIG. 1, with the face 16 there are associated in any known manner (for example by a hot shrinkage fit) two portions 20 forming separate bodies with respect to the reflecting element 10 and including a plurality of fins 22 facing the compartment 17. Preferably, these portions are arranged in positions corresponding with the concavities 12 facing the lamps 6. 
     It, this respect, in order to strike said portions 20 with a suitable air flow and hence cool the reflecting element 10, a fan 24 (or similar cooling element) is provided in the compartment 17 and driven by a usual electric motor 25 powered in any known manner. This fan is operated on activation of the lamps 5 or, alternatively, during discrete spaced-apart time periods. During the use of the cooktop 1, the lamps 5 generate light and heat. 
     Those rays 11 generated by said lamps which do not directly reach the hob 1 are reflected towards it by the reflecting element 10. This latter therefore heats up and can reach high temperature. 
     By conduction, the heat is transferred from the surface 15 and those layers of the screen 10 below it to the surface 16 and from there to the portions 20. 
     The heat is removed from these latter by the air which comes into contact with the fins 22, which have a considerable heat transfer area compared with the surface 16. 
     In practice, the portions 20 &#34;draw&#34; heat from the reflecting element 10, so preventing it from reaching critical temperatures which could result in its mechanical weakening and/or in deformation which could be damaging to the proper use of the cooktop. 
     The heat emitted by the portions 20 is removed by forced convection by the air moved by the fan 24. 
     If the cooktop 1 is associated with the furniture unit 18, an aperture 27 is provided in a wall 18A thereof to connect the compartment 17 to the room containing the furniture unit 18 (such as a kitchen). A grille 28 is placed over the aperature 26. 
     Consequently during the preparation of a food contained in a container resting on the cooktop 1, the fan 24 is operated (either directly as a result of the operation of lamps 5 or via a suitable fan switch 29 located on the control panel 30 of the heat generators 5, or following the operation of the lamps 6 but with a suitable delay set by a usual timer connected to a usual electrical feed circuit for the lamps 5). 
     The operation of the fan results in greater cooling of the portions 20, making them more efficient in removing the heat from the reflecting element 10. 
     Another embodiment of the invention is shown in FIG. 3, in which parts corresponding to those of FIGS. 1 and 2 are indicated by the same reference numerals. 
     in this embodiment a fan 24 is again associated with the cooktop 1, but the aluminum screen 10 comprises, associated with the face 16, a body 38 having high emissive power or emittance. 
     The body 38 is prepared for example by depositing a layer of black or other dark coloured coating on said face. In a possible alternative, the body 38 is a solid body heat-shrunk onto the reflecting element 10 to obtain intimate contact therewith. During the use of the cooktop 1, the lamps 6 generate light and heat. 
     Those rays 11 generated by said lamps which do not directly reach the cooktop 1 are reflected towards it by the reflecting element 10. The reflecting element therefore heats up and can reach high temperature. 
     Again, the heat is transferred by conduction from the surface 15 and those layers of the reflecting element 10 below it to the surface 16 and from there to the body 38. 
     Because of its intrinsic characteristics, this embodiment emits a large part of the heat absorbed by the reflecting element towards the compartment 17 (see the arrows F in FIG. 1). 
     In practice the body 38 absorbs heat from the reflecting element 10, so preventing it from reaching temperatures which could result in its mechanical weakening and/or in deformation which could be damaging to the proper use of the cooktop. 
     The heat emitted by the body 38 is removed by forced convection by the fan 24, which directs the air so that it grazes the body 38, to remove from it the heat radiated by it. If the cooktop 1 is associated with the furniture unit 18, an aperture 27 (previously described) is provided to connect the compartment 17 to the room containing the furniture unit 18 (such as a kitchen). 
     A cooktop with cooled reflecting elements as described is of simple construction and enables possible malfunction deriving from damage to the screens or reflecting elements associated with its light and/or heat generators to be prevented, where such damage is related to excessive heating. 
     In addition, the upper surface of said hob on which the food containers are placed for food preparation can be raised to a very high temperature, so allowing better and quicker food treatment.