Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2001-03-23
2001-10-09
Paik, Sang (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S448190
Reexamination Certificate
active
06300604
ABSTRACT:
This invention relates to a radiant electric heater particularly, but not exclusively, for use in cooking appliances, such as glass-ceramic cooking appliances.
BACKGROUND TO THE INVENTION
Radiant electric heaters are well known comprising a base of thermal and electrical insulation material having at least one electrical heating element supported on or adjacent thereto. The base may comprise compacted microporous insulation material and may be provided in a dish-like support, such as of metal.
The heating element or elements is or are generally of elongate coiled wire or ribbon form, having electrical terminations at opposite ends thereof for connection to a power supply.
A rod-like temperature-responsive device is also generally provided extending at least partly across the heater and overlying the heating element or elements.
DESCRIPTION OF PRIOR ART
In one known arrangement, the heating element is provided in a pattern incorporating one or more reversals and such that both ends of the element are situated at the periphery of the heater and preferably close to each other, where they can be readily provided with electrically conductive terminations, such as in a terminal block, to enable the element to be connected to a power supply.
However another arrangement is known in which the heating element is arranged in a pattern such that one end is at the periphery of the heater and the other end is at a location in the heater remote from the periphery, for example at or near the middle of the heater. With such an arrangement, which may occur when the heating element is provided in the form of a simple spiral, it is necessary to provide a wire link connected to that end termination of the heating element located remote from the periphery of the heater and extending to the periphery of the heater. One such wire link is known, provided externally of the heater and passing through an aperture at the centre of the base of the heater. However a wire link of this nature, passing through the base, increases the overall depth of the heater, which is undesirable.
Alternatively, a wire link is known which is provided in or beneath the insulation material of the base. However, the provision of such a link necessitates additional processing steps in the manufacture of the heater, thereby adding to the cost of the heater.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome or minimise these disadvantages.
SUMMARY OF THE INVENTION
The present invention provides a radiant electric heater comprising a base of thermal and electrical insulation material, an electrical heating element supported relative (on or adjacent) to the base and having a terminal region at a location in the heater remote from a periphery of the heater, a rod-like temperature-responsive device extending at least partly across the heater from the periphery thereof at least to a region proximate the terminal region of the heating element, and electrical connecting means extending from the terminal region of the heating element to the periphery of the heater by way of the rod-like temperature-responsive device.
The rod-like temperature-responsive device may comprise a differentially-expanding rod and tube assembly having a rod arranged inside a tube and adapted to operate switch means at a periphery of the heater.
The rod and/or the tube may comprise a metal and serve as the electrical connecting means.
The tube may also include an electrical lead passing therethrough and serving as the electrical connecting means.
The tube may be provided with at least two bore-holes passing therethrough, one containing the rod and the other containing the electrical lead serving as the electrical connecting means.
The tube may comprise an electrical insulating material, such as a material selected from ceramic, glass, glass-ceramic, quartz and fused vitreous silica, and the rod may comprise a metal.
Alternatively the rod-like temperature-responsive device may comprise a tube in which is provided an electrical element having an electrical parameter which changes as a function of temperature. Such electrical element may comprise an electrical resistance device whose electrical resistance changes as a function of temperature.
The tube in which the electrical element is provided may comprise a metal and serve as the electrical connecting means.
Alternatively the tube in which the electrical element is provided may include an electrical lead passing therethrough which is electrically connected to the terminal region of the at least one heating element and serves as the electrical connecting means. In this case the tube may comprise an electrically insulating or conducting material, such as a material selected from metal, ceramic, glass-ceramic, quartz and fused vitreous silica.
The electrical heating element may be of wire, ribbon, film or foil form and may be arranged substantially in the form of a spiral.
By means of the invention, an electrical connection can be readily provided from a region of a heating element remote from the periphery of a heater to a peripheral region of the heater by way of the rod-like temperature-responsive device, thus eliminating the need for a lead buried in or beneath an insulation base of the heater, or for a lead passing through an aperture in the base of the heater.
For a better understanding of the invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:
REFERENCES:
patent: 4538051 (1985-08-01), Schreder et al.
patent: 5270519 (1993-12-01), Higgins
patent: 5420398 (1995-05-01), Petri et al.
patent: 5796075 (1998-08-01), Gross et al.
patent: 5961867 (1999-10-01), McWilliams
patent: 6051816 (2000-04-01), Wilkins
patent: 0948239 (1999-10-01), None
patent: 1212941 (1970-11-01), None
European Search Report Aug. 25, 2000.
Ceramaspeed Limited
Dorman Ira S.
Paik Sang
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