ELECTRIC HEATER FOR HEATING FOOD OR BEVERAGES

Abstract: An electric heater for use in a vehicle, to heat a container of food or beverage, includes a flexible jacket that is wrapped around the container to be heated, and an electrical lead and plug for connecting the heater to a source of electrical power, such as the cigarette lighter socket of a vehicle. The flexible jacket consists of inner and outer cover layers. Sandwiched between the inner and outer layers are a flexible layer of electrical conductive material, and a flexible insulating layer disposed between the layer of electrically conductive material and the outer cover layer. The electrical heating element is connected to the electrical lead, to receive power supplied thereby.

Description: El ec t r i c hea t er for hea t i ng food or beverages FIELD OF THE INVENTION The present invention relates to electric heaters for use in vehicles for heating containers of food or beverages. BACKGROUND OF THE INVENTION Drivers or passengers who travel in a vehicle for a long distance, especially in rural area at night, often find it difficult, if not frustrating, to obtain hot food or beverage in order to keep them in good physical conditions. This is a particularly difficult problem for parents travelling with babies or small chidren. Cooking devices are available in some vehicles, however, they are mostly bulky, expensive and their installation are always limited to luxurious limosines. There is therefore a great need for a heater for food and beverage which is portable and personal and can operate from the power supply of a vehicle, thereby saving the trouble of carrying extra batteries on a trip. There are, however, some problems which have severely hampered the development of such a heater. Firstly, the heater must be water resistant so that any fluid spillage to the heating element will not cause a short circuit of the vehicle power supply. Secondly, as the food or beverage will be heated up to the boiling point of water, the internal structure of the heater in the vicinity of any heating element must be fire resistant. Thirdly, the heater must be able to operate at a relatively low voltage, e.g. 12 or 24 volts, compatible with the vehicle power supply system and its power consumption must be small to avoid draining the battery of a vehicle in a short time. Finally, during operation, the exterior of the heater must be maintained at a relatively low temperature such that the user will not be burnt. SUMMARY OF THE INVENTION According to the present invention, there is therefore provided an electric heater for use in a vehicle for heating a container of food or beverage comprising a flexible jacket adapted to be wrapped around the container, said jacket including an inside layer for contact with a container to be heated, an outside layer, a flexible electric heating element secured to a layer of thermally conductive material and disposed between said inside and outside layers, and thermal insulating layer disposed between said layer of thermally conductive material and said outside layer. Preferably the heating element is embodied by and in contiguous contact with two layers of thermally conductive material and an electrical plug is provided for connecting the electric heating element to the cigarette lighter of a vehicle. Preferably the layer of thermally conductive material includes an aluminium sheet or plural sheets of a metallic material, at least one of the said sheets having a fabric backing to prevent cracking thereof. The said metallic material is preferably aluminium. Preferably a layer of heat containment material is disposed between said insulating layer and said thermally conductive material. The electric heater according to the present invention allows a wide range of different containers to be heated while travelling, for example a baby's bottle or a hot dog in a paper bag or a sealed can of food. While the invention has been described with respect to one preferred embodiment, it will be appreciated that many other variations, modifications and applications of the invention may be made. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present invention will be further described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the electric heater showing the inside surface of the jacket, that is to say the surface which contacts the container; Figure 2 is an alternative perspective view, showing the outside of the jacket; Figure 3 is a perspective view of the electric heater in use in heating a baby's bottle; and Figure 4 is an exploded perspective view of the electric heating element; and, Figure 5 is a cross-sectional view through the flexible jacket. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, the electric heater comprises a flexible fabric jacket 1, a flexible electric heating element 2 (shown in Figures 4 and 5) whose outer surface is provided with suitable electrical insulation, an electric lead 3 and a power plug 4 for connecting the electric heating element to the cigarette lighter socket of a vehicle, self- adhesive tabs 5a, 5b on the inside surface of the jacket and 6a, 6b on the outside surface of the jacket which co-operate in closing the jacket, self-adhesive tabs 7 and 8 for holding the closed jacket in a flattened configuration when not in use, and an eye 9 to allow the electric heater and a container being heated to be hung from a hook in the interior of the vehicle. In use, as best seen in figure 3, the jacket 1 is wrapped around a container, in this case a baby's bottle indicated by dashed lines, and is closed. The jacket 1 and the container are then hung by means of the loop 9 from a hook in the vehicle, and the plug 4 is inserted into the cigarette lighter socket of the vehicle. The electric heating element 2 causes the inside surface of the jacket 1 to be heated, and the heat is transmitted to the container, thereby warming the contents of the container. Referring now to Figures 4 and 5, the jacket 1 comprises a heating element 2 which is preferably made of an electrically resistive material with an insulating coating on the outside and is formed into a multitude of U-shaped bends. The heating element 2 is embodied between an outer backing sheet Id and an inner backing sheet le, each backing sheet comprises an aluminium sheet and a polyester yarn backing such that the heating element and the aluminium surfaces are in substantially contiguous contact with each other. The heating element is secured onto the aluminium surface of one of the backing sheets to prevent dislocation or tangling of the heating element 2 after several uses. Aluminium sheet is used because it is flexible, can sustain high temperature generated by the heating element 2 without being burnt and can quickly distribute the heat generated by the heating element 2 evenly across the whole surface of the inner backing sheet le because of its good thermal conductivity. The immediate advantage of a quick distribution of heat is to obviate the problem of localised burning due to the generated heat which concentrates along the length of the heating element. Also, the polyester yarn backing serves to protect the aluminium sheet by protecting it from being folded into sharpe creases and then cracking. In addition, a cotton layer lc and a sponge layer lb are provided as a thermal insulator to prevent useful heat from escaping or leaking to the external surface of the present invention. Thus the combined effect of the layers lb and lc is to ensure that the generated heat flows towards the subject to be heated while leaving the external surface at a sufficiently low temperature that it can be safely and comfortably handled. The cotton layer has an added advantage of being a fire-guard layer as pure cotton is fire-resistant. Further, the inside If and outside la surfaces are preferably made of a water resistant material, e.g. nylon, such that any liquid spillage would not result in short-circuit of the heating element which might lead to damage of the vehicle power supply system.

Claims: C L A I M S 1) An electric heater for use in a vehicle for heating a container of food or beverage comprising: a flexible jacket adapted to be wrapped around the container, said jacket including an inside layer (10 for contact with a container to be heated, an outside layer (la), a flexible electric heating element (2) secured to a layer of thermally conductive material and disposed between said inside and outside layers, and a thermal insulating layer disposed between said layer of thermally conductive material and said outside layer. 2) An electric heater according to claim 1 , characterised in that the heating element (2) is embodied by and in contiguous contact with two layers of thermally conductive material (Id & le). 3) An electric heater according to claim 1 or 2, characterised in that there is provided an electrical plug for connecting said electric heating element to the cigarette lighter of a vehicle. 4) An electric heater according to any of the preceeding claims, characterised in that the layer of thermally conductive material includes an aluminium sheet. 5) An electric heater according to any of the preceecing claims, characterised in that said layer of thermally conductive material comprises plural sheets of a metallic material, at least one of the said sheets having a fabric backing to prevent cracking thereof. 6) An electric heater according to claim 5, characterised in that the said metallic material is aluminium. 7) An electric heater according to claim 1 or 2, characterised in that a layer of heat containment material is disposed between said insulating layer and said thermally conductive material.

Inventors: NG WAI-MAN, NG, WAI-MAN
Applicants: NG WAI MAN, NG, WAI-MAN
Application year: 1995
Main classification: H05B3
IPC codes: H05B3