GB1581129A

GB1581129A - Electrical heating devices

Info

Publication number: GB1581129A
Application number: GB2750979A
Authority: GB
Original assignee: VULCAN REFRACTORIES Ltd
Current assignee: VULCAN REFRACTORIES Ltd
Priority date: 1976-12-24
Filing date: 1976-12-24
Publication date: 1980-12-10

Description

(54) ELECTRICAL HEATING DEVICES (71) We, VULCAN REFRACTORIES LIMITED, a British Company of Brookhouses Industrial Estate, Cheadle, Stoke-on-Trent, Staffordshire, ST10 1PN, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to electrical heating devices of the kind comprising an electrical heating element embedded in a body of refractory ceramic material.

Heating devices of this kind emit long wave infrared radiation and are useful in particular in industrial applications for warming, drying, curing and like purposes.

In our co-pending Patent Application No.

39688/75 (Serial No. 1,581,127) from which the present Application is divided we have claimed an infra-red heating device comprising a solid body part of refractory ceramic material and a heating element wholly embedded in such body part with all surfaces thereof in intimate contact with such material, the body part having a corrugated or quasi-corrugated surface thereto defining alternate side-by-side peaks and troughs, and the heating element having successive reaches thereof in register with respective such peaks and so located in relation thereto as at least to extend to that side of a notional plane extending between the bottoms of the troughs immediately adjacent the said respective peaks remote from such peaks.

The present invention is concerned with the provision of uniformity of heating from devices of the kind disclosed in our copending Application aforesaid, and has particular reference to devices wherein the body part is of plate-like form and includes an integral mounting projection extending outwardly from a face thereof.

According to the present invention an infra-red heating device comprises a platelike body part of refractory ceramic material and an electrical heating element wholly embedded in such body part with all surfaces thereof in intimate contact with such material, the body part having a corrugated surface at one external face thereof, such surface defining alternate side-by-side peaks and troughs, and an integral mounting projection at the opposite external face thereof and the heating element having successive reaches thereof in register with respective such peaks, characterised in that the heating element is extended at a position in register with the projection to provide an increased heat input in such region.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which: Fig. 1 is a rear perspective view of one form of a heating device according to the invention; Fig. 2 is a plan view of the front of the devce of Fig. 1; Fig. 2A is a diagrammatic plan view of the heating element of the device of Fig. 1; and Fig. 3 is a section on the line Ill-Ill of Fig. 2.

With reference to the drawings, a heating device comprises a general planar rectangular ceramic body 1 having a coiled resistive wire heating element 2 (Fig. 3) embedded therein.

The body has a smooth flat rear surface 3 and a front surface (as shown in Fig. 2) which has raised portions 4 and troughs 5, element 2 being embedded in the body in register with the raised portions 4 therein and the troughs 5 lying between the raised portions 4.

The element 2 is of a single length having two free ends and, as can seen from Fig. 2, comprises six equally spaced longitudinal reaches 6 extending parallel to the longer sides of the body 1, two lateral reaches 7 parallel to and adjacent the shorter sides of the body, and a short central linking reach 8 which extends parallel to the lateral reaches 7. The manner in which the element 2 is arranged is shown diagrammatically in Fig. 2A, and it will be seen that the central linking reach 8 is provided at a free end of the element 2.

Tn the centre of the rear surface of the body there is a projection 9 which is an integral part of the body 1 and serves for the mounting of the heating device and/or the attachment of a reflector plate (not shown) to the back of the device. In the embodiment shown there are grooves 10 on opposite sides of the projection 9 for engagement with a reflector plate retaining clip.

The free ends of the heating element 2 pass through the projection and terminate in electrical connection tags 11. The exposed portions of the ends are insulated with ceramic sleeve elements 12.

Two parallel bores 13 (Fig. 2) extend completely through the ceramic body 1 and projection 9 and a thermocouple 14 or other temperature sensor (Fig. 3) may be supported at a position in front of the front surface by leads 15 which pass through the bores and terminate in tags 16 (Fig. 1) which are insulated like the ends of the heating element 2.

The heating device so far described may be formed in the following manner : - A wet ceramic forming mixture is placed in a first mould part, such part being shaped to form the troughs 5 and raised portions 4 of the front face of the body 1. The element 2 is placed on the mixture and a second mould part shaped to form the back face 3 and projection 9 of the body 1 is positioned on the first mould part. Further wet mixture is inserted into the mould through an inlet in that part of the second mould part which is shaped to form the projection 9. The wet mixture is then allowed to settle, for say 35 minutes, and make intimate contact with all surfaces of the heating element 2.

If bores 13 for a temperature sensor are required these are formed by means of metal tubes inserted into the mixture in the mould.

The moulded body incorporating the heating element 2 is then inserted into an oven to dry the body and glaze the exposed surfaces thereof.

With this arrangement it is possible to form a strong yet light heating element which is an efficient emitter of long wave infra-red and which can heat up and cool down quickly whilst possessing sufficient thermal inertia to level out temperature fluctuations in use. The dimensions of the front surface of the device may be 47" by 2A" and the thickness may be 2l8 at the raised portion and i" between same.

The heating element 2 may be 250W 240V a.c. rating.

The device may be used for any suitable domestic, commercial or industrial purpose.

For example, it may be used for drying, curing or heating purposes. It is hard wearing and has a long life. In particular, it can withstand splashes of cold water when at operating temperature, and stains on the front surface thereof are easily burnt off in use.

The distribution of the heating element 2 over the front surface and particularly the provision of the short linking element 8 in register with the projection, ensures that an even heating effect over the surface can be achieved. The ceramic body 1 is thin walled and of constant thickness (except for the variation between the raised portions 4 and the recessed portions 5) apart from the central region which has the projection 9 thereat.

The heating device as shown may be other than flat, and in particular, the body may be part-cylindrical in form. A body of this form acts to focus the heat, and thus a higher temperature can thereby be achieved.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiments which are described by way of example only, and thus for example, a heating device according to the invention may be formed in any suitable size and shape and may be used for any suitable purpose.

Attention is drawn to our copending Patent Application No. 27508/79 (Serial No.

1,581,128) also divided from Patent Application No. 39688/75 (Serial No. 1,581,127) and of which the claims are directed specifically to a method of forming the infra-red heating device hereindisclosed.

WHAT WE CLAIM IS: 1. An infra-red heating device comprising a plate-like body part of refractory ceramic material and an electrical heating element wholly embedded in such body part with all surfaces thereof in intimate contact with such material, the body part having a corrugated surface at one external face thereof, such surface defining alternate side-by-side peaks and troughs, and an integral mounting projection at the opposite external face thereof and the heating element having successive reaches thereof in register with respective such peaks, characterised in that the heating element is extended at a position in register with the projection to provide an increased heat input in such region.

2. A heating device as claimed in claim 1, wherein the heating element is an elongated metal heating element.

3. A heating device as claimed in claim 2, wherein the heating element is a coiled wire.

4. A heating device as claimed in any one of the preceding claims, wherein the extension to the heating element is of like form to the remainder of such element.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. central linking reach 8 is provided at a free end of the element 2. Tn the centre of the rear surface of the body there is a projection 9 which is an integral part of the body 1 and serves for the mounting of the heating device and/or the attachment of a reflector plate (not shown) to the back of the device. In the embodiment shown there are grooves 10 on opposite sides of the projection 9 for engagement with a reflector plate retaining clip. The free ends of the heating element 2 pass through the projection and terminate in electrical connection tags 11. The exposed portions of the ends are insulated with ceramic sleeve elements 12. Two parallel bores 13 (Fig. 2) extend completely through the ceramic body 1 and projection 9 and a thermocouple 14 or other temperature sensor (Fig. 3) may be supported at a position in front of the front surface by leads 15 which pass through the bores and terminate in tags 16 (Fig. 1) which are insulated like the ends of the heating element 2. The heating device so far described may be formed in the following manner : - A wet ceramic forming mixture is placed in a first mould part, such part being shaped to form the troughs 5 and raised portions 4 of the front face of the body 1. The element 2 is placed on the mixture and a second mould part shaped to form the back face 3 and projection 9 of the body 1 is positioned on the first mould part. Further wet mixture is inserted into the mould through an inlet in that part of the second mould part which is shaped to form the projection 9. The wet mixture is then allowed to settle, for say 35 minutes, and make intimate contact with all surfaces of the heating element 2. If bores 13 for a temperature sensor are required these are formed by means of metal tubes inserted into the mixture in the mould. The moulded body incorporating the heating element 2 is then inserted into an oven to dry the body and glaze the exposed surfaces thereof. With this arrangement it is possible to form a strong yet light heating element which is an efficient emitter of long wave infra-red and which can heat up and cool down quickly whilst possessing sufficient thermal inertia to level out temperature fluctuations in use. The dimensions of the front surface of the device may be 47" by 2A" and the thickness may be 2l8 at the raised portion and i" between same. The heating element 2 may be 250W 240V a.c. rating. The device may be used for any suitable domestic, commercial or industrial purpose. For example, it may be used for drying, curing or heating purposes. It is hard wearing and has a long life. In particular, it can withstand splashes of cold water when at operating temperature, and stains on the front surface thereof are easily burnt off in use. The distribution of the heating element 2 over the front surface and particularly the provision of the short linking element 8 in register with the projection, ensures that an even heating effect over the surface can be achieved. The ceramic body 1 is thin walled and of constant thickness (except for the variation between the raised portions 4 and the recessed portions 5) apart from the central region which has the projection 9 thereat. The heating device as shown may be other than flat, and in particular, the body may be part-cylindrical in form. A body of this form acts to focus the heat, and thus a higher temperature can thereby be achieved. It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiments which are described by way of example only, and thus for example, a heating device according to the invention may be formed in any suitable size and shape and may be used for any suitable purpose. Attention is drawn to our copending Patent Application No. 27508/79 (Serial No. 1,581,128) also divided from Patent Application No. 39688/75 (Serial No. 1,581,127) and of which the claims are directed specifically to a method of forming the infra-red heating device hereindisclosed. WHAT WE CLAIM IS:

1. An infra-red heating device comprising a plate-like body part of refractory ceramic material and an electrical heating element wholly embedded in such body part with all surfaces thereof in intimate contact with such material, the body part having a corrugated surface at one external face thereof, such surface defining alternate side-by-side peaks and troughs, and an integral mounting projection at the opposite external face thereof and the heating element having successive reaches thereof in register with respective such peaks, characterised in that the heating element is extended at a position in register with the projection to provide an increased heat input in such region.

5. A heating device as claimed in any

one of the preceding claims, wherein the heating element, at a position in register with the projection includes aligned reaches which terminate in spaced apart disposition and wherein such element is extended, at one of the opposing ends, so as to continue in a direction inclined to the direction of the said reaches.

6. A heating device as claimed in claim 5, wherein the extended region of the said end is inclined approximately at right angles to the direction of the said reaches.

7. A heating device as claimed in any one of the preceding claims, wherein the heating element comprises a single wire and has connecting wires which extend through the projection for support thereby.

8. A heating device as claimed in any one of the preceding claims having a temperature sensor arranged on or forwardly of the corrugated surface thereof.

9. A heating device as claimed in claim 8, wherein the sensor has connecting leads which extend through bores in the ceramic body.

10. A heating device as claimed in claim 9, wherein the said connecting leads are supported by the projection.