HEATING ELEMENTS

Abstract: There is disclosed a temperature changing apparatus having a temperature changing element mounted on a sintered metal substrate, the use of sintered metal in an method of manufacture of same, an d methods of manufacture of same.

Description: Heating Elements The present invention concerns novel heating elements and methods of manufacture of same. Many types of heating and cooling elements ("temperature changing elements") are known. For example, printed ceramic heating elements, which are formed upon a metal substrate. The metal substrate acts to provide mechanical support and to conduct heat. One metal frequently used is steel, particularly with ceramic heating elements which currently cannot be formed on other metal substrates due to the process and temperature required, as well as the chemistry of the surface necessary for effective bonding of the ceramic. The present invention provides improved heating elements, particularly ceramic heating elements. According to the present invention, there is provided temperature changing apparatus having a temperature changing element mounted on a sintered metal substrate. By "temperature changing apparatus" and "temperature changing element" is meant an apparatus and element which causes the transfer of heat, thus incorporating both heating and cooling apparatus and elements. The present inventor has found that the use of sintered metal provides a number of distinct advantages over the use of metals or alloys as substrates. The sintered metal may, for example, be steel or it may be a combination of steel and at least one other metal, e.g. a metal such as copper having a higher thermal conductivity than steel. The use of sintered metal provides a substantial weight advantage over solid metal, for example, a 50%-80% reduction in the case of steel. Due to the reduced mass of substrate to be heated or cooled, it also improves the thermalconductivity of the substrate, allowing for a more efficient and rapidly responsive control of heating or cooling. This is particularly useful in the case of e.g. irons, kettles and toasters. The thermal conductivity of the sintered metal may be further enhanced by the use of an additional metal in the sintered substrate, the additional metal having a higher thermal conductivity than the first metal used. For example, copper could be used in addition to steel. The additional metal may be added during the sintering process, or afterwards. In order to provide the optimum surface to act as a substrate for the temperature changing element, the sintered metal may be coated with a material which facilitates attachment to (i.e. mounting of) the temperature changing element. For example, a sintered steel and copper substrate may be coated with a film of steel only a few microns thick in order to facilitate and optimise its attachment to a ceramic heating element. Furthermore, the sintered metal substrate may be arranged in order to facilitate the evaporation or condensation of a liquid throughout its volume. Thus it could be arranged to form the sole plate of an iron, a source of water being supplied to it and steam being formed throughout its volume and thus across the whole of its surface. A similar arrangement could be employed in any cleaning, pressing or steam producing appliance or apparatus. Also provided according to the present invention is the use of sintered metal in a method of manufacture of a substrate for the temperature changing element of temperature changing apparatus. Also provided according to the present invention is a method of manufacture of temperature changing apparatus comprising forming a temperature changing element on a sintered metal substrate. The invention will be further apparent with reference to the accompanying drawings, in which :- Figure 1 shows a first heater element with sintered metal substrate; Figure 2 shows a second heater element with sintered metal substrate; and Figure 3 shows a third heater element with sintered metal substrate A first heater element with sintered metal substrate comprises ceramic heating element 10 attached to sintered steel substrate 20. Heating element 10 is connected by wires 11,12 to power source 13. A second heater element with sintered metal substrate comprises ceramic heating element 10 attached to a fine film of steel 30 coated on sintered steel substrate 20. Heating element 10 is connected by wires 11,12 to power source 13. A third heater element with sintered metal substrate comprises ceramic heating element 10 attached to sintered steel and copper substrate 40. Heating element 10 is connected by wires 11,12 to power source 13.

Claims: CLAIMS 1. Temperature changing apparatus having a temperature changing element mounted on a sintered metal substrate. 2. Temperature changing apparatus according to claim 1, being a heating and/or cooling apparatus. 3. Temperature changing apparatus according to either one of claims 1 or 2, the sintered metal comprising steel. 4. Temperature changing apparatus according to either one of claims 1 or 2, the sintered metal comprising steel and at least one other metal. 5. Temperature changing apparatus according to claim 4, the sintered metal comprising steel and copper. 6. Temperature changing apparatus according to any one of the preceding claims, the sintered metal being coated with a film of material facilitating mounting of the temperature changing element. 7. Temperature changing apparatus according to claim 6, the sintered metal being coated with a film of steel facilitating mounting of the temperature changing element. 8. Temperature changing apparatus according to any one of the preceding claims, the temperature changing element comprising a ceramic heating element. 9. Steam producing apparatus comprising temperature changing apparatus according to any one of the preceding claims, the temperature changing element being a heating element. 10. Steam producing apparatus according to claim 9, comprising an iron. 11. The use of sintered metal in a method of manufacture of a substrate for the temperature changing element of temperature changing apparatus. 12. A method of manufacture of temperature changing apparatus, comprising forming a temperature changing element on a sintered metal substrate.

Inventors: LARGE WILLIAM THOMAS, PANAGHE STYLIANOS, LARGE, WILLIAM, THOMAS, PANAGHE, STYLIANOS
Applicants: DELTA THETA LTD, LARGE WILLIAM THOMAS, PANAGHE STYLIANOS, DELTA THETA LIMITED, LARGE, WILLIAM, THOMAS, PANAGHE, STYLIANOS
Application year: 1998
Main classification: H05B33
IPC codes: H05B3