Abstract:
A food heater having a base arranged to receive food, a heating system in the base, and a cover configured to form, with the base, a closed chamber in which food may be positioned during food preparation. A photovoltaic system is in the cover. The photovoltaic system has one or more solar cells adapted to absorb solar energy and store the solar energy in one or more batteries. The heating system is adapted to receive the solar energy when the cover is connected to the base, to thereby facilitate food preparation in the food heater.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a food heater or cooker for cooking and food preparation. In particular, the present invention relates to a food heater based on solar energy. 
       BACKGROUND OF THE INVENTION 
       [0002]    Powerful kitchen appliances conceived to bake, such as ovens, microwaves and hot plates, are frequently used for short time periods according to modern food habits. In particular, these electric appliances, such as microwaves, are used to reheat or defrost food. A drawback of such appliances is that they waste a lot of energy. 
         [0003]    As an alternative, solar ovens based on solar energy enable the reduction of the energy waste. However, the cooking is often time-consuming and rather constraining. 
         [0004]    A further drawback of existing solar and microwave ovens is that it is difficult to obtain intermediate levels of temperature, which limits the quality and precision of cooking. 
         [0005]    Thus, there is a need for providing improved cookers or food heaters which would overcome some of these problems. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the present invention is to wholly or partly overcome the above disadvantages and drawbacks of the prior art and to provide improved cookers or food heaters. 
         [0007]    The present invention provides a food heater or cooker which enables reduction of the waste of energy when cooking. 
         [0008]    Hence, according to a first aspect of the present invention, a food heater is provided. The food heater includes a base arranged to receive food and comprising a heating system. The food heater includes also a cover or cap arranged to form with the base a closed chamber in which food is positioned during food preparation. The cover or cap comprises a photovoltaic system adapted to absorb and load solar energy. The heating system is powered by the loaded energy received from the cover when the cover is connected to the base during food preparation. 
         [0009]    The present invention is based on an insight that a photovoltaic system may be incorporated in a container or recipient to absorb and load solar energy for cooking or heating. 
         [0010]    Although the photovoltaic system is preferably arranged in the cover, the photovoltaic system may also be arranged in the base of the food heater. 
         [0011]    The food heater according to the present invention is advantageous as it enables cooking with solar energy, thereby reducing energy waste. The energy loaded in the cover is transferred to the base, which, in turn, warms up the food placed inside the closed chamber by means of the heating system. 
         [0012]    The present invention is particularly advantageous for short cooking periods, which, with conventional ovens, waste a lot of energy. The inventive food heater reduces significantly the waste of energy since it is based on solar energy. 
         [0013]    The present invention is also advantageous in that an ecological food heater is provided. 
         [0014]    Another advantage of the present invention is that cooking becomes cheap since solar energy is used. 
         [0015]    According to an embodiment, the base of the food heater is arranged to receive a food container to be positioned within the closed chamber and in thermal contact with the base, which is advantageous since the use of a food container protects the interior surface of the base. The use of an intermediate food container is also advantageous as the size of the food container may be chosen in function of the amount of food to be cooked or prepared, thereby optimizing the heating process. 
         [0016]    According to an embodiment, the heating system comprises an induction heating device, which is advantageous since quasi instantaneous heating may be obtained. The food heater is therefore fast, thereby enabling fast cooking suitable to modern cooking habits. 
         [0017]    According to an embodiment, the food container is made of steel, which is suitable for cooking by induction. 
         [0018]    According to an embodiment, the cover comprises a solar absorbent coating surface. In particular, the photovoltaic system may be made of spray-on solar cells which are nanoparticles of silicium sprayed on the surface of the cover. 
         [0019]    According to an embodiment, the base has the form of a container in which food is positioned. In particular, the base and the cover form a hermetical container, thereby limiting loss of heat during food preparation. 
         [0020]    According to an embodiment, the food container has a shape matching the shape of the base. 
         [0021]    According to an embodiment, the base has a flat bottom forming a hot plate on which food or a food container may be placed. In particular, the hot plate is covered with a vitroceramic coating, which is suitable for a heating system comprising an induction device. Further, a vitroceramic surface has the advantage to spread heat quickly and to be easy to clean without any chemical products, thereby rendering the food heater user-friendly and ecological. 
         [0022]    According to an embodiment, the food heater may comprise at least one temperature sensor arranged to detect the temperature in at least one of the cover, the base and the food container, which is advantageous since this provides a food heater with very precise control of the temperature and thereby the baking degree of a preparation. 
         [0023]    According to an embodiment, at least one of the cover and the base comprises an indicator indicating if the energy stored in the photovoltaic system is above a predefined value. Alternatively, the indicator may comprise more than one predefined values. A predefined value may correspond to a value above which a particular type or mode of cooking is not possible, e.g. if the energy loaded in the cover or cap is not sufficient. The indicator is preferably, but not necessarily, arranged at the base. 
         [0024]    According to an embodiment, at least one of the cover and base comprises a keypad or keyboard to select a cooking program or mode. 
         [0025]    According to an embodiment, the cover has at least one ear arranged to grip the food heater, which is advantageous as the food heater may become hot. The ears of the heater are preferably made of plastic material. 
         [0026]    According to an embodiment, the base forms a cavity, which is advantageous if the food heater is not used with a food container. A cavity enables the formation of the closed chamber in which food may be placed. 
         [0027]    According to an embodiment, the opening of the cavity of the base or the food container is ellipsoidal and comprises edges on which the cover rest during food preparation. In particular, the edges of the base are further arranged to receive the food container. 
         [0028]    According to an embodiment, the photovoltaic system comprises a semi stationary battery which enables the loading of energy. 
         [0029]    The present invention is advantageous since it combines a sustainable cookware and a high quality and precision in cooking. 
         [0030]    Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The above, as well as additional objectives, features and advantages of the present invention, will be better understood through the following detailed description and illustrative drawings, in which: 
           [0032]      FIG. 1  shows a food heater according to an embodiment of the present invention; and 
           [0033]      FIG. 2  shows an exploded view of a food heater according to an embodiment of the present invention. 
           [0034]      FIG. 3  illustrates the use of the cover of a food heater according to an embodiment of the present invention; 
           [0035]      FIG. 4  illustrates a scenario for use of a food heater according to an embodiment of the present invention; 
           [0036]      FIG. 5  illustrates a base of a food heater according to an embodiment of the present invention; 
           [0037]      FIG. 6  illustrates a display of a food heater according to an embodiment of the present invention; 
           [0038]      FIG. 7  shows examples of food containers according to embodiments of the present invention; and 
           [0039]      FIG. 8  shows an exploded view of a food heater according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    With reference to  FIG. 1 , a first embodiment of the present invention will be described. 
         [0041]      FIG. 1  shows a food heater  100  including a base  110  and a cover or cap  130 . The base  110  and the cover  130  are mounted together to form a closed chamber  150  within which food or a food preparation may be placed during food preparation. The empty volume corresponding to the interior of the base  110  is represented in white while the empty volume corresponding to the interior of the cover  130  is represented in black (dark). The cover  130  comprises a photovoltaic system  135  adapted to absorb and to load solar energy. The base  110  comprises a heating system  115  which is powered by the loaded energy received from the cover  130  when the cover  130  is connected to the base  110  during food preparation. 
         [0042]    The heating system  135  is adapted to heat up the food placed in the closed chamber  150 . The heating system  135  may be a resistance which, when powered by the energy loaded in the cover  130 , heats a region of the base  110  and thereby the food placed on it. Electronics or an electronic circuit  114  is arranged at the base  110  to receive the energy from the photovoltaic system  135  and power the heating system  115 . Alternatively, the electronics or electronic module  114  is a part of the heating system  115 . 
         [0043]    According to an embodiment, the base of the food heater is arranged to receive a food container  120 . In this case, the heating system is adapted to heat up the food placed in the food container  120 . 
         [0044]      FIG. 2  is an exploded view of a food heater  200  which illustrates where the food container  120  is arranged, namely in the closed chamber  150  between the cover  130  and the base  110 . The cover  130  is arranged to receive solar energy and, when connected to the base  110 , transfer this energy to the heating system  115  of the base  110 , e.g. via the electronics  114 . 
         [0045]    According to an embodiment, such as illustrated in  FIGS. 1 and 2 , the heating system comprises an induction heating device  113 , which, in operation, generates an electromagnetic field represented by the reference number  112  in  FIG. 1  and  FIG. 2 . Induction technology heats up food by creating an electromagnetic field between the induction heating device or coil  113  and the metallic food container  120  placed in contact with it. As soon as the container  120  is removed from the base  110 , the heat stops, like a natural switch. Consequently, there is no or very little loss of energy since the time to heat and cool down is very short, and a high precision cooking is achieved. 
         [0046]    Although the photovoltaic system  135  is represented by a block in  FIG. 1 , it is to be understood that the whole cover or a part of the cover  130  may be designed for absorbing energy. The block shown in  FIG. 1  may for instance correspond to a battery in which the absorbed solar energy is stored or loaded. In particular, the battery may be a semi-stationary battery which is adapted to accumulate energy during the day, e.g. corresponding to powers ranging from 50 to 200 Watts. 
         [0047]    According to an embodiment, the cover  130  comprises a solar absorbent coating surface. In particular, the surface of the cover  130  is sprayed by nanoparticles of silicium (so called DSSC solar cells), which spraying converts the surface in efficient photovoltaic panels. The DSSC cells are sensitive to both visible and non-visible radiation (infrared radiation), which means that they can produce energy even on a cloudy day. 
         [0048]    Further, the base  110  may comprise temperature sensors  111  enabling the control of the temperature in the food heater  100 . 
         [0049]      FIG. 3  illustrates how the cover may be exposed to sunlight or other radiations to absorb and load energy. In a first alternative, the cover  130   a  of the food heater is exposed to sunlight through a window. In a second alternative, the cover  130   b  of the food heater is suspended or attached in a kitchen and thereby permanently exposed to sunlight in order to accumulate a maximum of energy. The cover may rest in a place exposed to sun during the day, such as behind a window of a kitchen, and used in the evening for cooking. 
         [0050]    With reference to  FIG. 4 , a scenario, in which the food heater according to the present invention is used, will be described. 
         [0051]    In a first step  410 , an user of the food heater  100  selects one of the adapted containers among a plurality of or set of steel nesting containers, such as those depicted with reference to  FIG. 7 . The size of the selected container may be selected depending on the quantity of food to heat or on the level of cooking to be obtained since the container&#39;s shape and size directly affect the heating of the food preparation. The size of the flat bottom of the food container may for instance vary, thereby decreasing or increasing the size of the hottest regions of the food container. In a second step  420 , the user places his/her preparation or hot ingredients in the food container  120 . In a third step  430 , the user places the cover  130  on top of the base  110  and the food container  120 , thereby forming a hermetical container or closed chamber  150 . As soon as the cover  130  is in contact with the base  110 , an indicator  116 , e.g. in the form of a light line, indicates the level of energy stored in the cover  130 . Thus, in a fourth step  440 , the user checks whether the level of energy is sufficient. If the level of energy is not sufficient, the user may then choose to expose the cover to sunlight in a similar manner as in the examples described with reference to  FIG. 3 . If the level of energy is sufficient, the user may select a heating mode. Different types of heating mode will be described in the following with reference to  FIG. 6 . 
         [0052]      FIG. 5  shows a base of a food heater according to an embodiment of the present invention. The base comprises an indicator  116  arranged at an edge of the base  110 . Depending on the level of energy stored in the cover  130  and indicated by the indicator  116 , one of three different modes of cooking  117   a ,  117   b  and  117   c  may be available to the user. The indicator  116  comprises three regions delimited by two predetermined values, which regions correspond to the three modes of cooking. 
         [0053]    With reference to  FIG. 6 , three programs or modes of cooking are defined by predefined values of energy level. In a first mode  117   a , the food heater is set to keep an ingredient hot. This first mode  117   a  is suitable for recipes in which the temperature of the food has to be precisely controlled. In the present mode  117   a , the food heater may be used to keep ingredient at a constant temperature without the need of heating up the ingredient at the last moment, such as with conventional food heaters. This first mode  117   a  operates like an automatic standby mode in which the food heater memorizes the temperature of the preparation via a thermometer or temperature sensor  111  and autoregulates the heating system. 
         [0054]    In a second mode  117   b , which requires a higher level of energy than the first mode  117   a , thus only available to the user if sufficient energy is loaded in the photovoltaic system of the cover, the food heater is set to heat up a small quantity of food. The food heater may first measure the temperature of the food via a temperature sensor  111  and display the measured temperature on the display  119 . The user may then enter a desired temperature by means of the keys of the keypad or keyboard corresponding to the second mode  117   b.    
         [0055]    In a third mode  117   c , which requires a higher energy level than the first and second modes  117   a  and  117   b , the food heater may be set to defrost, melt, dry or evaporate an ingredient. Thus, in this mode  117   c  the food heater has loaded enough energy in the photovoltaic system of the cover  130  to transform a food&#39;s state. 
         [0056]    The heating time may be controlled with the lateral buttons, which is displayed on the display  119 . The present mode  117   c  is suitable for small quantities or delicate ingredients which require a particular attention. 
         [0057]    With reference to  FIG. 7 , a set of food containers  120  is described. The food containers  120  may have an ellipsoidal or oval opening  121  and a flat bottom  122  matching the bottom of the base  110 . The food container  120  may also comprise an ear  123  enabling to grip and to lift the container from the food heater. The ear may preferably be made of polymer or hard plastic materials. Further, the food container may comprise an edge  124  arranged to rest on a corresponding edge of the base  110  of the food heater  100 . Examples of sizes for the food containers shown in  FIG. 7  ranges from 250 to 390 mm in length (from the ear  123  to the edge  124 ), i.e. along the y-axis represented in  FIG. 7 , and from 55 to 280 mm in width, i.e. along the x-axis represented in  FIG. 7 . 
         [0058]      FIG. 8  shows an exploded view of a food heater according to an embodiment of the present invention. The food heater  800  comprises a cover  830  equivalent to the cover described with reference to  FIG. 1-3 , a base  110  equivalent to the base described with reference to  FIG. 1-3 . The base and the cover are arranged to receive a food container  820  equivalent to the food containers described with reference to  FIG. 7 . The base  810  comprises an indicator, a display and keypads for three modes of cooking, which indicator, display and modes are equivalent to that described with reference to  FIGS. 5 and 6 . 
         [0059]    Although the invention above has been described in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the scope of the invention as defined by the following claims.