KR20060085186A - Radiant electric heating element - Google Patents

Abstract

Within the electric heater the luminescent electric heating element is suitable to be supported upright on the first type edge 16 on the base 8 of the insulating and electrically insulating material, facing the first (16) and second (18) sides. An elongate ribbon 12 of electrically conductive material having a longitudinal edge. The second longitudinal edge 18 of the extension ribbon 12 is provided with a plurality of electrically conductive pins 20 spaced along the length to form electrically conductive bands of varying height H.

Description

Luminescent Electric Heater Element {RADIANT ELECTRIC HEATING ELEMENT}

1A-1D are top views of electric heaters that include an alternative arrangement of stretch ribbon heating elements.

2A is a side view illustrating an embodiment of a prior art stretch ribbon heating element for use in the heaters of FIGS. 1A-1D.

2B is an illustration of the elongate ribbon heating element after forming the corrugation.

3A is a side view of an embodiment of an extension ribbon heating element according to the present invention for use with the heaters of FIGS. 1A-1D.

3B is an illustration of the stretch ribbon heating element of FIG. 3A after pleating.

4 and 5 show a further fin arrangement and a side view of an alternative embodiment of an extension ribbon heating element according to the invention.

FIG. 6 is a side view showing the legs extending at the first longitudinal edge and illustrating a modification of the stretch ribbon heating element of FIG. 3A. FIG.

<Description of the symbols for the main parts of the drawings>

8: base

12: elongation ribbon heating element

16: first class edge

18: type 2 edge

20: electrically conductive pin

 In an electric heater the invention is suitable for being supported upright on a first longitudinal edge on a base of a thermally insulating and electrically insulating material, the light emitting comprising an extension ribbon of electrically conductive material having first and second opposing longitudinal edges. Relates to an electric heating element. Such electric heaters are well known for use in cookers, for example behind a crystallized glass surface.

Heaters for cooker applications, such as crystallized glass-ceramic cooking hobs, typically include and are known as one or more luminescent electrical heating elements in the form of elongated ribbons supported on the base of insulating and electrically insulating materials. The ribbon consists essentially of the sinusoidal general wave form and is always supported on the base of the insulating material. The corrugated ribbon is formed from a unique flat ribbon of predetermined height and thickness.

The legs are at least partially fitted within the base of the insulating material and are provided extending from the lower edge of the stretch ribbon. However, it is desirable to insert the plain continuous lower edge of the ribbon at the base of the insulating material and to remove these legs.

In order to form the desired heating power, it is necessary to accommodate a specific length of the stretching ribbon of a predetermined thickness and height in the effective space inside the heater. The corrugation treatment is chosen such that the required length of the flat ribbon is compressed to the length of the entire wave shape suitable for the dimensions of the particular heater. The degree of compaction achieved is generally known as the crinkle factor and is defined as the ratio of the length of the original flat ribbon to the required total length of the pleated ribbon.

It is important to ensure that the surface power loading on the ribbon heating element does not exceed a certain maximum, otherwise the service life is not essentially reduced. This surface power loading is determined by distributing the total power of the heater by the surface area of the ribbon heating element. In particular, problems arise with small heaters and maximum achievable pleat factors, ensuring adequate electrical clearance between windings in close proximity as windings within the effective space of the heater and accommodating the required length of wave-shaped ribbon heating elements. It will prove to be impossible or extremely difficult. Shortening of the ribbon heating element results in excessively high power and temperature. This problem arises when the ribbon heating element, except for the legs, has a plain continuous lower edge partially sandwiched in the base of the insulating material.

It is an object of the present invention to minimize and overcome the above problems.

According to the invention, in order to form electrically conductive bands of varying heights, the second longitudinal edge of the stretch ribbon is provided with a plurality of electrically conductive fins spaced apart along its length, and insulated from the electric heater and of the electrically insulating material. A light emitting electric heating element is provided that is suitable for being uprightly supported on a first longitudinal edge on a base and comprising an elongated ribbon of electrically conductive material having first and second opposite longitudinal edges.

The pins are provided to form essentially coplanar with the elongate ribbon and are configured to be the same thickness as the elongated ribbon, provided integrally with the elongated ribbon, and formed of the same material as the elongated ribbon.

The stretch ribbon is suitable for supporting the first longitudinal edge sandwiched within the base of the insulating and electrically insulating material.

The first longitudinal edge of the stretch ribbon consists of essentially continuous planes.

Alternatively, the first longitudinal edge of the elongated ribbon is suitable for at least partially fitting to the base of the extinguishing and electrically insulating material, and a spaced leg extending from the first longitudinal edge is provided. The spaced legs are provided in the same material as the elongated ribbon and are fixed or provided integrally with the elongated ribbon.

The elongate ribbon is provided in a corrugated shape.

The pins are provided in corresponding corrugated shapes.

The stretch ribbon comprises an ion-chromium-aluminum alloy.

The stretch ribbon has a thickness of about 20 to 200 microns, and preferably has a thickness of about 30 to 100 microns.

The pins each have a height of approximately 0.5 to 10 mm, and preferably each has a height of approximately 1 to 3 mm.

The pins each have a length of at least 1 mm and each has a length of up to approximately 10 mm.

The pins are spaced at least 1 mm apart and up to approximately 20 mm apart.

The pins are spaced approximately 3 mm apart and have a length of approximately 3 mm.

The present invention relates to an electric heater provided with a luminescent electric heating element, as defined above, and comprising a base of thermal insulation and electrical insulation. The base of the insulating and insulating material includes microporous heat and electrical insulating material.

By means of the electrically conducting pins in the present invention, a relatively small length of the stretch ribbon heating element can be provided to achieve the desired end-to-end electrical resistance and heating power. The heat is electrically heated to a size that is relatively smaller than the main portion of the stretch ribbon heating element but is conducted into the fin from the pins, which contribute to the electrical resistance, from the main portion of the stretch ribbon heating element. The surface area provided with the fins results in full cooling of the heating element. The present invention has the significant advantage that it is particularly difficult to accommodate the required length of the elongate ribbon heating element within the dimensions of the electric heater in which the first type edge is fitted to the base of the insulating and electrically insulating material and is configured in the shape of a continuous plate.

BRIEF DESCRIPTION OF DRAWINGS In order to show that the effects have been more clearly understood and to better understand the present invention, reference is made to examples of the accompanying drawings.

Referring to FIG. 1A, the electric heater 2 is provided for use in a cooker, for example as behind a crystallized glass surface of a cooking hob. The heater 2 is a dish-like support 4 of metal containing a base layer 8 composed of insulating and electrically insulating materials such as microporous thermal and electrically insulating materials. It includes. A peripheral wall 10 made of insulating material is formed inside the support 4 such as a dish. A radiant electric heating element 12 is formed to support the base layer 8. The heating element 12 comprises multiple windings of elongated ribbons in which the ribs of electrically conductive material supporting the edges on the base layer 8 are preferably comprised of an ion-chromium-aluminum alloy. At the side of the heater the heating element 12 has ends electrically connected to a terminal block 14, thereby being electrically connectable to a power supply for energizing. 1B-1D show an alternative implementation of an electric heater 2 formed in essentially the same manner as the heater 2 of FIG. 1A except for the winding of the electric heating element 12 in the form of an elongated ribbon arranged in a different shape. An example is shown.

2A and 2B show a prior art stretch ribbon heating element 12 for use in the electric heater 2 of FIGS. 1A-1D. The elongate ribbon heating element 12 has first and second long edges 16, 18, respectively, which constitute a continuous plane. The elongate ribbon heating element 12 thus comprises a plain band or strip of electrically conductive material (ie an essentially continuous material which does not form essential grooves or consists of an elongated form), preferably Preferably from about 30 to 100 microns, from 20 to 200 microns, and have wrinkles as shown in the edge-on view of FIG. 2B.

In the first longitudinal edge 16 an elongate ribbon heating element 12 is inserted into the base layer 8 of thermal insulation and insulation material.

In order to form the desired heating power for the heater 2, it is necessary to accommodate a specific length of the elongate ribbon heating element 12 of predetermined height and thickness within the effective space in the heater. The corrugating process is chosen such that the required length of the flat elongated ribbon heating element is compressed to the overall corrugated length so that it fits the dimensions of the particular heater. The degree of compression achieved is generally known as the pleat rate and is formed as the ratio of the length of the ribbon element that is basically flat to the required total length of the wavy ribbon element 12.

Surface power loading on the stretch ribbon heating element 12 should not exceed a predetermined maximum, otherwise the service life of the element should be essentially reduced. This surface power loading is determined as the total power of the heater 2 is distributed by the surface area of the stretch ribbon heating element 12.

In particular, problems arise in the heater 2 of small size and in the maximum attainable pleating factor, which ensures adequate electrical clearance between windings which are simultaneously adjacent as windings within the effective space of the heater and that of the corrugated ribbon heating element 12 It will be proven that it is impossible or extremely difficult to accommodate the required length. This will be illustrated by the following example.

A 165 mm diameter heater 2 is required to integrate the extension ribbon heating element 12 to provide 1200 watts of power from a supply voltage of 230 volts. The stretch ribbon heating element 12 is required to have an electrical resistance value of 42.8 ohms upon cooling. Electrical requirements are met by a ribbon heating element 12 having a length of 6180 mm and a width (or length) w of 4.1 mm and a thickness of 50 microns prior to pleating. This ribbon heating element 12 has a surface area of approximately 507 cubic centimeters and provides a surface power loading of 2.37 per cubic centimeter. This surface power loading is considered to be allowed to the maximum in order to ensure a satisfactory service life for the heating element 12.

In order to secure the stretch ribbon heating element 12 with the heater 2, it is necessary to compress the stretch ribbon heating element 12 to a length by corrugating. However, the required crinkle factor is so large for practical attainment that it allows the required electrical spacing between adjacent windings of the element provided when the element is mounted to the heater 2. This problem is minimized or overcome in the present invention by the apparatus shown in FIGS. 3A and 3B. As shown in FIG. 3A, as the band of electrically conductive material varies in height H along its length, the electrically conductive cooling fins 20 are spaced along the essential length of the heating element 12, A second longitudinal edge 18 of the corrugated elongate ribbon heating element 12 is provided. The fin 20 is suitably formed of the same material as the stretch ribbon heating element 12 and is preferably provided as an integral part of the heating element 12. The fin 20 is provided to resonate essentially with the elongate ribbon heating element 12 and is configured to be essentially the same thickness as the elongate ribbon heating element 12. The fins 20 are suitably formed according to the pleats of the elongate ribbon heating element 12. The pins 20 suitably each have a height of about 0.5 to about 10 mm, preferably about 1 to 3 mm. The pins 20 suitably have lengths of at least 1 mm and up to 10 mm, respectively. The pins 20 are preferably spaced apart by a distance d of at least 1 mm and up to approximately 20 mm. In a separate embodiment, the fins 20 are spaced apart by a distance d of approximately 3 mm, having a height h of approximately 2 mm and a length l of approximately 3 mm. In a separate embodiment according to the apparatus of 3A, which is principally described with respect to FIG. 2A, the width (or height) w of the stretch ribbon heating element 12 is reduced compared to FIG. 2A. In the example of the apparatus of FIG. 3A, the width (or height) w of the elongate ribbon heating element 12 is 3.5 mm compared to the 4.1 mm width of the exemplary apparatus of FIG. 2A. The pin 20 has a height h of 2 mm, a length l of 3 mm and a separation distance d of 3 mm. According to the apparatus of FIG. 3A, the fins 20 and the elongate ribbon heating element 12 are required to form an end-to-end electrical resistance of 5630 mm and 42.8 ohms before pleating. This is compared with the corresponding length of 6180 mm required for the elements of the illustrative embodiment of FIG. 2A. After the degree of pleat is easily achieved, the relatively short element is easily accommodated in a 165 mm diameter heater 2. The surface power loading and surface area of the exemplary stretched ribbon heating element 12 together with the fins 20 provides a service life in which the corresponding example device of FIG. 2A and the exemplary heating elements on both sides are essentially equally satisfactory. It is formed essentially as shown.

In the apparatus of FIG. 3A, although the fin 20 contributes little to the overall electrical resistance of the heating element, heat is generated essentially in the main body of the elongate ribbon heating element 12 than in the fin 20. . However, heat is quickly conducted and quickly conducted inside the fin 20, and is released. The fin 20 contributes significantly to the overall heat release function of the heating element.

In an illustrative embodiment of the apparatus according to FIG. 3A, the cooling fins 20 are added with a surface area with a heating element equivalent to an added continuous strip of width 1.0 mm along the length of the basic elongated ribbon heating element 12. However, the pin 20 is an element equivalent to that provided by a continuous strip of width 0.24 mm added along the length of the basic elongate ribbon heating element 12, with only electrical resistance added.

The cooling fins 20 can be formed in any desired shape. 4 shows the elongated ribbon heating element 12 provided with a relatively low number of effects of the pin 20 which is widely spaced apart from the non-vented side edges. FIG. 5 shows an extension ribbon heating element 12 provided with a relatively high number of effects of closely spaced fins 20.

As shown in FIG. 6, the fin 20 and the elongate ribbon heating element 12 are suitable to be at least partially fitted into the base 8 of a heat insulating or electrically insulating material, and the first type of heating element 12. Legs 22 are provided which extend from the edge 16 and are spaced apart. The spaced legs 22 consist essentially of the length and are provided in the same material as the elongated ribbon heating element 12 and are either fixed or provided integrally with the elongated ribbon heating element 12. Since the leg 22 consists of a standardized length, the height H of the band is independent of the length of the leg.

Claims (26)

Suitable for being uprightly supported on a first long edge 16 on a base 8 of thermal insulation and electrically insulating material in an electric heater, and the first (16) and second (18) A radiant electric heating element comprising an elongate ribbon 12 of electrically conductive material with opposite longitudinal sides,  The second longitudinal edge 18 of the stretch ribbon 12 is characterized in that it is provided with a plurality of electrically conductive fins 20 spaced apart along the length to form electrically conductive bands of varying height H. Heating element. 2. Heating element according to claim 1, characterized in that the fins (20) are used as cooling fins. 3. Heating element according to claim 1 or 2, characterized in that the fins (20) are formed of the same material as the stretching ribbon (12). 4. Heating element according to claim 3, characterized in that the fins (20) are provided integrally with the stretching ribbon (12). Heating element according to any of the preceding claims, characterized in that the fins (20) are provided with the same thickness as the stretching ribbon (12). Heating element according to any of the preceding claims, characterized in that the fins (20) are provided coplanar with the elongate ribbon (12). Heating element according to any of the preceding claims, characterized in that the stretching ribbon (20) is suitable for supporting a first longitudinal edge (16) fitted in a base (8) of thermally insulating and electrically insulating material. Heating element according to any of the preceding claims, characterized in that the first longitudinal edge (16) of the stretching ribbon (12) is a continuous plane. 8. The first longitudinal edge 16 of the stretchable ribbon 12 is suitable for at least partly fitting to the base 8 of a thermally insulating and electrically insulating material, according to claim 1. And a leg 22 extending from the longitudinal edge and spaced apart. 10. Heating element according to claim 9, characterized in that the spaced legs (22) are provided of the same material as the stretching ribbon (12). 11. Heating element according to claim 9 or 10, characterized in that the spaced legs (22) are fixed or provided integrally with the extension ribbon (12). 12. Heating element according to claim 9 or 10 or 11, characterized in that the legs (22) are of uniform length. Heating element according to any of the preceding claims, characterized in that the elongated ribbon (12) is provided in a corrugated form. 14. Heating element according to claim 13, characterized in that the fin (20) is provided in the shape of a corresponding waveform. Heating element according to any of the preceding claims, characterized in that the stretching ribbon (12) comprises an ion-chromium-aluminum alloy. Heating element according to any of the preceding claims, characterized in that the stretching ribbon (12) has a thickness of about 20 to 200 microns. 17. Heating element according to claim 16, wherein the stretching ribbon (12) has a thickness of about 30 to 100 microns. Heating element according to any of the preceding claims, characterized in that the fins (20) each have a height of approximately 0.5 to 10 mm. 19. Heating element according to claim 18, characterized in that the fins (20) each have a height of approximately 1 to 3 mm. Heating element according to any of the preceding claims, characterized in that the fins (20) each have a length of at least 1 mm. 21. Heating element according to claim 20, characterized in that the fins (20) each have a length up to approximately 10 mm. Heating element according to any of the preceding claims, wherein the fins (20) are spaced at least 1 mm apart. 23. Heating element according to claim 22, characterized in that the fins (20) are spaced up to approximately 20 mm. Heating element according to any of the preceding claims, characterized in that the fins (20) are spaced approximately 3 mm apart and have a length of approximately 3 mm. In an electric heater comprising a base 8 of thermal and electrical insulating material, The electric heater, characterized in that the light emitting electric heating element (12) is provided as claimed in the preceding paragraph. 26. The electric heater as claimed in claim 25, wherein the base (8) of the insulating and electrically insulating material comprises microporous thermal and electrically insulating material.

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