GB2364890A

GB2364890A - Securing planar heating element in liquid heating vessel

Info

Publication number: GB2364890A
Application number: GB0018245A
Authority: GB
Inventors: Robert Andrew O'neill; Antonio Martin Gaeta; Peter Hallam Wright
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 2000-07-25
Filing date: 2000-07-25
Publication date: 2002-02-13
Also published as: WO2002007575A1; AU2001266224A1; GB0018245D0

Abstract

An electrically-powered, liquid-heating vessel comprises a main body part 1 having an open bottom and a widened portion 7, an annular part 4 which encircles the main part 1 and has been moved down it until a portion 9 of the annular part 4 abuts against the widened portion 7, a planar heating element 3 disposed just beneath the open bottom of part 1 and a bottom closure 5 secured to the annular part 4 and serving to hold the heating element 3 in place. Main body part 1 may be of glass and a seal 2 may be disposed between the heating element 3 and the bottom of the glass body. Closure 5 may support the element 3 either indirectly through a control unit 6 or directly by means of pillars (12, Figure 4). Annular part 4 may be formed integrally with a handle and spout moulding, Figure 4.

Description

2364890 IMPROVEMENTS RELATING TO ELECTRICALLY HEATED VESSELS

Field of the Invention:

This invention concerns improvements relating to electrically heated vessels, particularly electrically powered liquid heating vessels such as kettles, hot water jugs, pots, pans, ums, laboratory equipment and the like. More particularly, the invention concerns improvements relating to the assembly of planar electric heating elements into the bodies of such vessels.

Back,oxound of the Invention; Planar heating elements as used in liquid heating vessels as abovementioned are commonly of two different types, namely the underfloor type which comprises a metal plate having a sheathed heating element clamped or clenched to the underside thereof and the thick film type which comprises a resistance heating track or layer formed on the underside of an electrically insulating substrate, commonly a stainless steel plate provided with a glass insulating layer. Such planar heating elements give rise to particular problems as regards their assembly into the bodies of liquid heating vessels and there have been many proposals for effecting such assembly.

In GBA-2 315 204 for example a planar heating element is secured into an aperture in the bottom of a vessel by provision of a flange surrounding 2 such aperture and having a plurality of through holes enabling studs or bolts on the heating element periphery to be passed through the flange for securing the heating element to the flange, a gasket seal being provided between the heating element and the flange.

In GB-A-2 330 064 an alternative proposal has abutments provided within the vessel body and the planar heating element is urged against and retained relative to such abutments by means of a circlip arrangement which interacts with formations provided in the wall of the vessel body, a resilient seal of elastomeric material being provided around the periphery of the heating element and providing sealing between the heating element and the surrounding internal surface of the vessel wall.

A variation of the proposal of GB-A-2 330 064 is the subject of GB-A-2 344 506 and is concerned particularly with the problems of fixing planar heating elements into glass bodied vessels which are subject to dimensional variations greater than those encountered in plastics bodied vessels. In accordance with the teachings of G13A-2 344 506, the arrangement of GB-A-2 330 064 is modified so that the seal acts between the periphery of the heating element and the external surface of the glass vessel, rather than the internal surface as in the arrangement taught in GB-A-2 330 064. Since glass vessels are generally blown and formed in a mould, their outer dimensions can be fairly accurately controlled, which is not generally the case for their internal dimensions, so that by providing sealing 3 between the heating element and the vessel exterior a more satisfactory solution can be achieved.

Notwithstanding the above proposals, problems can still arise in the assembly of planar heating elements to glass bodied vessels. The proposal of GB-A-2 315 204 necessitates the provision of holes in a flange in the bottom of the vessel and this is not a straightforward matter for glass vessels. The proposal of GB-A-2 344 506 requires the provision of some additional support means for the heating element and this can compromise the styling of the product. It has been proposed in GB-A-2 344 506 to use adhesive as a means of securing the assembly, but this is not preferred on account of cost and curing time considerations.

Proposals for overcoming the abovementioned problems are described in our British Patent Application No. 00 16050.7 filed 29 June 2000.

Objects and Summary of the Invention:

The object of the present invention is to provide yet a further proposal for overcoming or at least substantially reducing the abovementioned problems.

According to the present invention, the body of an electrically heated liquid heating vessel comprises a body part proper with an open bottom to which a planar heating element is fitted, a base part which encircles the bottom of the body part proper with an outwardly-extending abutment that is 4 provided around the bottom of the body part proper in abutment with and beneath an inwardly-extending part of the base part, and a bottom closure secured to the base part and serving to hold the planar heating element in place.

Described hereinafter is an exemplary embodiment of the invention in which the body part proper is formed of glass and has a region of increased diameter just above a cylindrical sealing region adjacent its open bottom, such increased diameter region constituting the abovementioned outwardly-extending abutment. An annular plastics moulding constitutes the base part and is arranged to be slipped over the top of the glass body part proper, and this moulding has a mating neck region which fits against the upper surface of the increased diameter region of the glass body part proper so that the latter cannot pass through the moulding, this neck region constituting the abovementioned inwardly-extending part of the base part, ie. the moulding. The moulding has support features to which the bottom closure is affixed and the bottom closure in turn has support features which bear against the underside of the planar heating element and urge the heating element periphery against the bottom of the glass body part proper. A seal is provided between the heating element periphery and the glass body part proper, for example in accordance with the teachings of GB-A-2 344 506 abovementioned, and preferably has a part which extends between the heating element and the glass so as to act as a thermal barrier which has the effect of reducing thermal stressing of the glass.

The above and further features of the present invention are set forth in the appended claims and will be more fully explained in the following description which is given with reference to the accompanying drawings.

Descri13tion of the Drawings:

Figure 1 is a cross-sectional showing of an exemplary embodiment of the present invention; Figure 2 is an enlarged showing of the part of Figure 1 that is within the circle C; Figure 3 is an exploded perspective view showing the component parts of the embodiment of Figures 1 and 2; Figure 4 is a cross-sectional showing of another exemplary embodiment; Figure 5 is a cross-sectional showing of the glass body part proper of the embodiment of Figure 4; and Figure 6 is an enlarged showing of the part of Figure 5 that is within the circle A.

6 Detailed Description of the Embodiments:

Referring first to Figures 1, 2 and 3, which show a first embodiment, Figure 1 shows a cross section through a simplified assembly, Figure 2 shows an enlargement of the seal and support area of Figure 1, and Figure 3 shows an exploded view of the components. A glass body 1 has a bulge 7 around its lower end, with a parallel section 8 of reduced diameter below the bulge. A cover/support moulding 4 fits over the glass body 1 and has a tapered region 9 which mates with the upper surface 10 of the bulge 7. The glass body 1 is entered into the support moulding 4 from below, and the support moulding sits on the bulge, preventing the glass body from passing right through. A bottom cover component 5 (which may be a plastics moulding or a metal pressing) is fastened to the support moulding 4 by means of suitable fasteners (not shown) which engage with the bores 11. The bottom cover 5 supports the heating element plate 3, either directly via pillars or indirectly through a control 6 which is mounted on the bottom of the element 3. The control 6 might be an X4 control or an X2 with associated mounting brackets, or an X2 and CP7 combination, either the X4 or the X2 and CP7 combination giving a 3600 cordless connection. The bottom cover 5 is arranged to press the heating element 3 against the bottom edge of the glass body 1. A seal 2 is positioned between a vertical flange of the heating element 3 and the lower parallel section 8 of the glass body, and may also extend between the bottom edge of 7 the glass body and the horizontal surface of the element so as to act as a heat shield preventing contact between the heating element and the glass. The seal 2 is shown as having a simple 'U' section, but could be of any shape, advantageously the finned "Easifix" shape (everted or otherwise), to accommodate tolerances of the glass vessel.

The X2 control is available from us and is substantially as described in GB-A-2 283 156, GB-A-2 306 801, GB-A-2 312 142, GB-A-2 315 366, GB-A-2 317 544 and GB-A-2 307 602. The X4 control is also available from us and is substantially as described in WO-A-9954903. The CP7 is a 3600 cordless connector component and, together with its mating CS4 connector, is available from us and is substantially as described in GB-A-2 285 716.

Easifix seals are the subject of GB-A-2 330 064 and GB-A-2 344 506.

Figures 4 to 6 show views of a more complete embodiment of the invention. Figure 4 shows a cross section through a jug provided with an element mounting according to the invention. The jug vessel body 1' has a tapered, curved form. In order for the system to work, the top of the vessel body must be of smaller diameter than the bulge section, so that it can pass through the support moulding 4'. In Figure 4 the support moulding is formed as an integral part of a handle and spout moulding, and means are shown for clipping the spout part to the upper rim of the glass vessel. Not shown is a sealing means to prevent drips leaking from between the moulding and the rim of the vessel. Figure 4 also shows the use of pillars 12 to support the 8 heating element, rather than by use of a control as in Figure 1. The construction according to Figure 4 gives a straightforward assembly operation without need for any special equipment or adhesives, although adhesives could be used if desired, the moulded seal being replaced with RTV silicone rubber (bath tub sealant) for example. As shown, a steam control 13 may be mounted in the handle, with the wires being led down a duct formed between the vessel and the moulding. Alternatively the steam control could be mounted in the space between the heating element and the bottom cover (a Z5 directly mounted to an X4, for example), which would simplify the support moulding and the handle form. The handle could, for example, be a single moulding of a rigid foam filled type to give the desired profile without multiple mouldings with their additional assembly and fastening requirements.

Figure 5 shows a detail of the glass vessel, with a magnified detail of the bulge region shown in Figure 6.

Steam controls, as is well known, serve to switch off or reduce the power supplied to a heating element when water is boiled and steam generated. The Z5 steam control is available from us and is substantially as described in GB-A-2 331 848.

The invention havina been described in the foregoing by reference to specific embodiments, it is to be appreciated that the described embodiments are exemplary only and that modifications and variations could be made thereto without departure from the spirit and scope of the appended claims.

9 For example, whereas the described embodiments have concerned glass bodied vessels, the same teachings could usefully be applied to vessels formed of other materials such as ceramics (porcelain) or earthenware for example.

Furthermore, whilst the described embodiments have an abutment formed as an outward bulge extending completely and continuously around the bottom of the vessel body, it would be possible to have a plurality of spacedapart abutment elements extending discontinuously around the vessel body. Since the abutment (bulge) serves only to prevent the vessel body part from passing completely through the base part, any form of abutment means that will accomplish this can be employed.

CLAWS:

1. An electrically heated vessel having a body which comprises a body part proper with an open bottom to which a planar heating element is fitted, a base part which encircles the bottom of the body part proper with an outwardly-extending abutment that is provided around the bottom of the body part proper in abutment with and beneath an inwardly-extending part of the base part, and a bottom closure secured to the base part and serving to hold the planar heating element in place.

2. A vessel as claimed in claim 1 wherein the vessel body is formed of glass and has a region of increased diameter adjacent to its open bottom, said regional constituting said outwardly-extending abutment.

3. A vessel as claimed in claim 2 wherein said base part comprises a metal or plastics material member which is configured to be able to be placed over the top of the vessel body and moved down until a comp lementarilyshaped region thereof engages said increased diameter region of the vessel body, said complimentarily-shaped region constituting said inwardly-extending part of the base part.

4. A vessel as claimed in claim 3 wherein said metal or plastics material member has support features providing for attachment of the bottom closure thereto.

5. A vessel as claimed in any of the preceding claims wherein the bottom closure has support features which bear against the underside of the planar heating element to hold it in place. 6. A vessel as claimed in any of the preceding claims wherein a seal is 10 provided between the planar heating element and the open bottom of the vessel body. 7. A vessel as claimed in claim 6 wherein the vessel body is formed of glass and the seal is formed so as to constitute a thermal barrier between the 15 planar heating element and the glass vessel body. 8. An electrically heated liquid heating vessel comprising a vessel body part having a top and an open bottom, a base part extending around the bottom of the body part, the base part being configured to be assembled with the body 20 part by insertion of the top of the body part into the base part and passing the body part through the base part until abutment means provided on the body part engages the base part to prevent further insertion, a base closure secured.

12 to the base part, and a planar heating element held in sealing engagement with the open bottom of the body part by means of the base closure.

9. An electrically heated liquid heating vessel substantially as herein described with reference to Figures 1 to 3 of the accompanying drawings or Figures 4 to 6 of the accompanying drawings.

10. A method of assembling a liquid heating vessel, said method comprising:

(i) forming a vessel body part having a top and an open bottom and wherein outwardly extending abutment means are provided around the vessel body at a location above its bottom; (ii) forming a vessel base part so that the vessel body part can be inserted therein, top first, until the abutment means on the body part engage the base part to limit further insertion; (iii) assembling a planar heating element sealingly with the open bottom of the vessel body part; and (1v) securing a base closure member to the base part to hold the heating element in place.