GB2300553A

GB2300553A - Heat source terminal arrangement

Info

Publication number: GB2300553A
Application number: GB9504825A
Authority: GB
Inventors: John Timothy Dobbs; Derek Peter Hurst; Melvin Jones; Robert Alan Law
Original assignee: GE Lighting Ltd
Current assignee: GE Lighting Ltd
Priority date: 1995-03-10
Filing date: 1995-03-10
Publication date: 1996-11-06
Anticipated expiration: 2015-03-10
Also published as: GB9504825D0; GB2300553B

Abstract

A heat source comprises a heating unit (1) with pinch seals (2) containing metal foils (7) through which electrical connection is made to the heating unit (1) in which rigid connectors (8) are connected to the foils (7) as lead in wires to provide connection to fitments in which the heat source is to be used.

Description

HEAT SOURCE The present invention relates to electrically energised heat sources. Embodiments of the invention relate to heat sources for use in cooker hobs, especially smooth top, e.g. ceramic hobs.

Figure 1 is a schematic illustration at one stage of manufacture of a known heat source for use in a ceramic hob.

Figure 2 is a schematic illustration at a subsequent stage of manufacture of the known heat source.

The heat source comprises a quartz tube 1 having end portions 2 closely adjacent and parallel, and a generally circular portion 3 between the ends 2. The tube contains a tungsten filament 4 dimensioned and arranged to produce a color temperature.of 2300K. The filament 4 is spaced from the internal wall of the tube 1 by spiral spacers 5, also of tungsten, as well known in the art.

The filament 4 is joined at each end to connectors known in the art as plugs 6. Each plug 6 is joined at one end to the filament 4 each plug 6 having a screw-fit with the filament 4. The plugs are connected at their other ends to metal foil 7 in pinch seals as also well known in the art. The foils 7 have external electrical conductors 8 welded to them. The conductors 8 are rigid. The tube 1 contains a fill of halogen gas e.g. a bromide, as well known in the art.

The known heat source is made in a large variety of sizes and power outputs, each size and power output being made for example in a. batch.

As shown in Figure 2, the rigid conductors 8 (which are, in practice, longer than shown in Figure 1) are cut short and then welded as indicated schematically by reference 9 to a multi-strand insulated flexible conductor 10 having insulation 11.

A cap 12 comprising a hollow ceramic body containing cement 13 is provided around the end of the pinch seal and the rigid conductor 8, the weld 9 and part of conductor 10 to protect the pinch seal and the welded join. The cap 12,13 prevents the conductor 8 bending and rotating relative to the pinch and the foil 7. If the conductor 8 bends or rotates it may break from the foil or fracture the glass within the pinch. The cap 12,13 also acts as an electrical insulator. The flexible conductor 10 is the lead-in to the heat source and joins the heat source to fitments used in the cooker hob. The fitments require the conductor 10 to extend at right angles to the axis of the pinch seals in the plane of the generally circular heat source 1.

Cutting the rigid conductor 8 and welding it to the flexible conductor 10 adds to the other manufacturing steps and increases manufacturing costs.

According to one aspect of the present invention, the cutting and welding steps are omitted, the flexible conductors 10 are not used, and the rigid conductors 8 are used as the lead-ins to provide connection to the fitments.

Preferably the rigid conductors 8, of the present invention are bent to extend at right angles to the axis of the pinch seals. The bent conductors 8 may extend within the plane of the circular heat source or out of that plane. In an alternative arrangement, the heat source is linear rather than circular and the conductors 8 are bent at right angles to the linear axis of the heat source.

According to another aspect of the present invention, there is provided a heat source comprising a tube of refractory material transparent to infra-red radiation, a filament of refractory electrically conductive material in the tube to produce the infra-red radiation when electrically energised, electrically coupled to foils in pinch seals of the tube and respective rigid conductors connected to the foils and extending out of the pinch seals, wherein each rigid conductor is bent to extend at right angles to its associated pinch seal, the rigid conductors providing the lead-ins for electrical and mechanical connection of the heat source to a fitment in which the heat source is used in operation.

The rigid conductors allow for simpler assembly of the heat source to a fitment. For example, a simple push-fit becomes possible and/or automated assembly is simplified.

Preferably means are provided to prevent the said rigid conductors transferring bending or rotating forces to the foils in the pinch seals. The said means may comprise a cap or caps, the conductors extending through the cap or caps to provide the said electrical and mechanical connection. The or each cap comprises for example a hollow ceramic body filled with cement, the pinch seals being partly embedded in the cement and the said conductors extending through the cap.

For a better understanding of the present invention, reference will now be made, by way of example to Figure 3 of the drawings which shows a detail of a heat source in accordance with the present invention, and to Figures 4A to 4C which show a novel spring clip arrangement useful in the invention.

The same reference numerals are used in Figure 3 as in Figures 1 and 2 to indicate the same items of the heat source.

As shown in Figure 3, the rigid conductor 8 which in Figure 2 is cut short and welded to flexible conductor 10] is left uncut, is bent at right angles to the pinch seal 2 and extends into and through the cap 12 and the cement 13 of the cap. The rigid conductor 8 itself thus provides the lead-in for the heat source. The conductor may be a two-part lead comprising a Molybdenum portion connected to the foil 7 and a solid Mn/Ni alloy portion 118 welded to the Molybdenum portion 18. It may be uninsulated as shown in Figure 3.

The cap 12 is a hollow ceramic body filled with cement 13 as known in the art. The end of the pinch seal is embedded in the cement. The cap and cement prevent the rigid conductor 8 bending or rotating relative to the foil 7 thereby preventing the weld of the conductor 8 to the foil 7 from breaking. Also the cap acts as an insulator.

The heat source may be circular as shown in Figure 1. The rigid conductors 8 extend from each pinch seal 2 and are bent at right angles thereto. The lead-in conductors 8 extend in the plane of the circular heat source, but may extend out of the plane. A separate cap 12,13 may be provided for each pinch seal or a single cap may be provided encompassing both seals in the circular heat source.

The heat source may be linear instead of circular.

The conductors 8 then extend through caps 12/13 at each end of the heat source and are bent to extend at right angles to the axis of the heat source.

The cap or caps 12/13 may be omitted and replaced by other means preventing the conductors 8 from bending and rotating relative to the seal 2 and foil 7. Such other means may be a spring clip 40 as shown in Figures 4A to 4C.

The spring clip is of spring steel and clips onto the pinch seal with the conductor 8 passing through a grip 41 in the base of the clip. The base and thus the grip are spaced from the bottom edge of the pinch 2 as indicated at 42. The grip 41 comprises a pair of tangs pressed out of the base. The tangs bite into the soft metal of the conductor 8. The spring clip transfers bending moments acting on the conductor away from the interface of the pinch with the conductor to the spring clip. This redistributes the resulting stresses across the full face of the pinch without damaging the pinch or the foil. Torsional motion of the conductor is resisted by the tangs and thus isolated from the foil although severe torsion would break the connection to the foil.

The spring clip 40 is considered inventive alone and also in combination with a heat source described herein or with a lamp of similar construction.

The rigid conductors are used to connect the heat source to a fitment in which they are used in e.g. a smooth top hob such as a ceramic hob. The conductors 8 may be provided with suitable electrical connectors as known in the art.

Alternatively the conductors 8 may simply plug into suitable push-fit sockets especially if they are bent out of the plane of the circular heat source. Because the conductors are rigid use of push-fit connectors is simplified and/or automated assembly becomes possible and/or is simplified.

Claims

1. A heat source comprising a heating unit with pinch seals containing metal foils through which electrical connection is made to the heating unit in which rigid connectors are connected to the foils as lead in wires to provide connection to the fitments in which the heat source is to be used.

2. A heat source as claimed in claim 1, wherein the rigid connectors are bent at right angles to the axis of the pinch seals.

3. A heat source as claimed in claim 2, wherein the heating unit is circular and the conductors extend out of the plane of the heating unit.

4. A heat source as claimed in claim 2, wherein the heating unit is circular and the conductors extend within the plane of the heating unit.

5. A heat source as claimed in claim 1 or 2, wherein the heating unit is is linear and the conductors are bent at right angles to the linear axis of the heating unit.

6. A heat source comprising a tube of refractory material transparent to infra-red radiation, a filament of refractory electrically conductive material in the tube to produce infrared radiation when electrically energised, pinch seals for the ends of the tube, electrically conductive foils in the pinch seals and to which the filament is connected and rigid conductors electrically connected to the foils to provide lead-ins for electrical and mechanical connection of the heat source to a fitment in which the heat source is used in

7. A heat source as claimed in claim 6, wherein the rigid conductors are each bent at right angles to the axis of its associated pinch seal.

8. A heat source as claimed in claim 7, wherein prevention means are provided for preventing transmission of bending or rotating forces to the foils in the pinch seals.

9. A heat source as claimed in claim 8, wherein the prevention means comprises a cap or caps, the conductors extending through the cap or caps to provide the electrical and mechanical connection.

10. A heat source as claimed in claim 9, wherein the or each cap comprises a hollow ceramic body filled with cement, the pinch seals being partially embedded in the cement and the rigid conductors extending through the cement to the pinch seals.

11. A heat source substantially as described herein with reference to figures 3, 4a, 4b and 4c of the drawings.