It is well known to provide a temperature-limiting device for an electric heater. Such an electric heater is typically arranged for location behind a surface to be heated, such as a glass-ceramic cooking surface, and generally comprises a dish-like support having therein at least one electric heating element. The temperature- limiting device comprises an elongate temperature- sensitive probe assembly, such as a differentially- expanding rod and tube assembly, arranged to operate one or more switch means located at one end of the probe assembly in a box-like housing.

It is known to provide at least one electrically conductive element, suitably of metal tab form, extending at one or more side faces of the housing of the temperature-sensitive probe assembly towards the dish- like support in a direction substantially parallel to a longitudinal axis of the temperature-sensitive probe

assembly. Such electrically conductive element or elements is or are arranged to be electrically connected, such as by welding, to one or more terminal regions of at least one electric heating element of the heater, extending from the dish-like support. The at least one electric heating element is commonly of corrugated metal ribbon form.

A problem has arisen with this arrangement in that when the temperature-limiting device is being assembled on the heater, an extended terminal region of the ribbon heating element may pass either side of its associated electrically conductive element, or may collide end-on with the electrically conductive element such that the terminal region of the ribbon heating element buckles.

As a result, necessary overlap for welding between the terminal region of the ribbon heating element and the electrically conductive element is not provided. The manner in which the terminal region of the ribbon heating element is presented to its associated electrically conductive element for welding cannot therefore be guaranteed.

It is an object of the present invention to overcome or minimise this problem.

According to the present invention there is provided a radiant electric heater comprising at least one electric heating element having terminal regions, the heating element being in the form of a corrugated metal ribbon; and a temperature-limiting device including a multiple- faced housing, a temperature-sensitive assembly extending from the housing at least partly across the at least one electric heating element, and first and second electrically conductive elements extending from opposing faces of the housing and connected to the terminal regions of the at least one electric heating element, wherein the first and second electrically conductive elements are directed such that both elements converge towards a longitudinal axis of the temperature-sensitive assembly.

The direction of the first electrically conductive element relative to the longitudinal axis may be different to the direction of the second electrically conductive element.

The first and second electrically conductive elements may extend at an acute angle to the longitudinal axis of the temperature-sensitive probe assembly. Such acute angle may be less than 30 degrees, preferably less than 20 degrees and suitably about 10 degrees.

The at least one electric heating element may be provided in a dish-like support. The first and second electrically conductive elements may be directed substantially normal to an arcuate rim of the dish-like support. The dish-like support may have a rim provided with at least one aperture through which the terminal regions of the at least one electric heating element extend. The dish-like support may comprise metal.

The electrically conductive element or elements may be of metal tab-like form and may be welded to the terminal regions of the at least one electric heating element.

The electrically conductive element or elements may be arranged substantially parallel to, or at a small angle to, the terminal regions of the at least one electric heating element upon engagement therewith prior to electrical connection formation.

The electrically conductive element or elements may be adapted and arranged to be accessible at side faces of the housing for the electrical connection thereto of the terminal regions of the at least one electric heating element.

The temperature-sensitive assembly may comprise an elongate temperature-sensitive probe assembly.

As a result of the angled arrangement of the electrically conductive elements on the temperature-limiting device, reliable alongside-engagement for welding, between a terminal region of the at least one electric heating element and its associated electrically conductive element, is obtained during assembly of the temperature- limiting device on the heater.

For a better understanding of the present 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 drawing which shows a plan view of an embodiment of a radiant electric heater according to the present invention provided with a temperature-limiting device.

Referring to the drawing, a radiant electric heater 2 is arranged for location beneath a surface 4 to be heated.

The surface 4 may be a cooking surface and may comprise glass-ceramic material.

The heater 2 comprises a dish-like support 6, such as of metal, containing a layer 8 of thermal and electrical

insulation material, such as microporous thermal and electrical insulation material. As shown, the dish-like support 6 is circular and has an arcuate peripheral rim 10.

At least one radiant electric heating element 12 is arranged inside the dish-like support 6. The heating element 12 is in the form of a corrugated metal ribbon arranged upstanding on edge in the dish-like support 6.

A temperature-limiting device 14 for the heater 2 comprises an elongate temperature-sensitive probe assembly 16 arranged to operate first and second switch means 18,20 located at one end of the probe assembly 16 in a multiple-faced housing 22, such as of ceramic material. The probe assembly 16 comprises a differentially-expanding rod and tube assembly of known form, although other forms of probe assembly could be provided, such as those incorporating a PRT sensor.

The first switch means 18 may be adapted for controlling supply of electric power from a voltage source to the heating element or elements 12. The second switch means 20 may be adapted to operate an indicating means, such as a warning light, for providing a warning signal when the surface 4 to be heated is too hot to touch.

The temperature-limiting device 14 is mounted on the heater 2 with the probe assembly 16 extending, from a front face of the housing 22, at least partly across the dish-like support 6 and overlying the heating element or elements 12. The housing 22 is located externally of the dish-like support 6 and secured thereto by means of a bracket arrangement 24.

The housing 22 has first and second opposite side faces 26,28. A first electrically conductive element 30 of tab form extends from the first side face 26 of the housing 22 and a second electrically conductive element 32 of tab form extends from the second side face 28 of the housing 22. The first and second electrically conductive elements 30,32 are accessible at the side faces 26,28 of the housing 22 and comprise metal, such as stainless steel or nickel-plated steel.

The first electrically conductive element 30 extends in a direction towards the dish-like support 6. The second electrically conductive element 32 also extends in a direction towards the dish-like support 6.

The first and second electrically conductive elements 30, 32 are each directed at an angle such that they extend non-parallel to, and are directed towards, a longitudinal

axis 34 of the temperature-sensitive probe assembly 16.

That is, the first and second electrically conductive elements 30,32 both converge towards the longitudinal axis of the temperature-sensitive probe assembly 16. The first and second electrically conductive elements 30,32 each extend towards the dish-like support 6 at an acute angle X to the longitudinal axis 34 of the temperature- sensitive probe assembly 16. Such acute angle X is less than 30 degrees, preferably less than 20 degrees, and suitably about 10 degrees. The angle X for the first electrically conductive element 30 may be different to the angle X for the second electrically conductive element 32.

The first and second electrically conductive elements 30, 32 may be directed substantially normal to the arcuate rim 10 of the dish-like support 6.

The corrugated ribbon heating element 12 has first and second terminal regions 12A, 12B extending through apertures provided in the rim 10 of the dish-like support 6 of the heater 2. The first terminal region 12A of the heating element 12 is welded, for example by spot welding, seam welding or other suitable means, directly to the first electrically conductive element 30 by a welding head arrangement 36 and the second terminal

region 12B of the heating element 12 is welded directly to the second electrically conductive element 32 by a further welding head arrangement 38.

When the temperature-limiting device 14 is assembled with the heater 2, by insertion of the probe assembly 16 through an aperture in the rim 10 of the dish-like support 6, the first and second electrically conductive elements 30,32 approach the first and second terminal regions 12A, 12B of the heating element 12 which extend from the dish-like support 6. The angled arrangement of the first and second electrically conductive elements 30, 32, as opposed to a prior art arrangement where the electrically conductive elements were arranged parallel to the longitudinal axis 34 of the temperature-sensitive probe assembly 16, ensures reliable engagement with the terminal regions 12A, 12B of the heating element 12, with minimal risk of collision of ends 30A and 32A of the electrically conductive elements 30,32 with the terminal regions 12A, 12B of the heating element 12. Any such collision could result in buckling of the terminal regions 12A, 12B of the heating element 12 and so preventing subsequent welding thereof to the electrically conductive elements 30,32.

It is not essential that the terminal regions 12A, 12B of the heating element 12 are approached by their corresponding associated electrically conductive elements 30,32 at the same angle, such that they are substantially parallel to one another. Indeed, a small difference in angles therebetween may be advantageous in assisting the welding operation by accommodating a kick experienced by the terminal region of a corrugated heating element when a welding electrode coincides with a peak of a corrugation in the terminal region of the heating element. Any angular variation in presentation of a terminal region 12A, 12B of the heating element 12 to its associated angled electrically conductive element 30,32 will tend to be accommodated as the terminal regions and their associated electrically conductive elements come alongside one another for the welding process to be effected.