GB2315204A

GB2315204A - A kettle containing a removable planar heating element

Info

Publication number: GB2315204A
Application number: GB9614872A
Authority: GB
Inventors: Robert Andrew O'neill; Antonio Martin Gaeta
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 1996-07-15
Filing date: 1996-07-15
Publication date: 1998-01-28
Anticipated expiration: 2016-07-15
Also published as: CN1135092C; WO1998002072A1; GB2315204B; GB9614872D0; HK1002548A1; CN1199328A; AU3550497A

Abstract

An electrically powered water heating vessel 7 has a removable planar heating element 1 sealingly secured to a mounting flange 6 on the vessel 7 by means of screw-threaded studs 2 which pass through apertures 5 of the mounting flange 6. Preferably there is a gasket seal 4 between the element 1 and flange 6. The element 1 may comprise a metal plate 10 having a sheathed wire wound resistance element 11 secured thereto or it may be an electrically insulating substrate carrying a resistance heating track (not shown). The vessel 7 may be cordless and may be provided with an element protector control (12, Fig. 2) for switching off the electricity should the element 1 rise above a predetermined temperature.

Description

IMPROVEMENTS RELATING TO ELECTRICALLY HEATED VESSELS Field of the Invention: This invention concerns improvements relating to electrically heated vessels, particularly electrically powered water heating vessels such as kettles, hot water jugs, pots, pans, urns, laboratory equipment and the like.

Background of the Invention: Electrically powered kettles and hot water jugs have traditionally employed a heating element in the form of a wire wound resistance heater which is mounted with insulation within a tubular metal sheath.

Sheathed heating elements of this kind have commonly incorporated an element head plate to which the heating element proper is affixed, and the head plate has provided for the attachment of the heating element to and in the associated appliance, an opening commonly being provided in a wall of the appliance for this purpose.

Planar electrical heating elements are however known and have been used for many years as hot plates in coffee making machines. One such planar element consists of an aluminium plate having a sheathed heating element as abovementioned cast or clenched to its underside. Planar heating elements have also been proposed which comprise a resistance heating track formed upon an electrically-insulating substrate by printing or by lithographic techniques; one such element comprises a stainless steel substrate which is coated on one side with glass or another electrically-insulating material, the resistance heating track being formed on the surface of the glass and then a further electrically-insulating layer being formed over the resistance heating track. The fitting of planar heating elements in water heating vessels has been considered to be advantageous, at least aesthetically since the vessel interior is then free from an intrusive element, but problems have been encountered with the fixing of the element as regards the serviceability of the vessel in the event that the element fails. Clearly it is undesirable that the entire vessel should have to be discarded in the event of failure of the heating element, but at the same time the fixing of the element in the vessel has to be such as to ensure that the vessel does not leak.

In US-A-3 308 225 there is described a technique for fixing a planar heating element mounting plate within a plastics bodied water heating vessel, the plastics body having a portion which seats the mounting plate and multiple projections upstanding from such mounting portion extending through holes formed in the periphery of the mounting plate and being thermally deformed so as in effect to rivet the element mounting plate in position. A similar technique used to fix a planar heating element in a plastics bodied water boiling vessel would clearly result in the element not being replaceable if it were to fail. In US-A-3 138 698 and in CA-A-1202659 a clench is formed around the periphery of the heating element mounting plate and is fitted around the lower edge of the vessel wall. Again, this latter technique results in an unserviceable element arrangement. More recently, GB-A-2 291 325 proposes to employ a sealing ring which captures the periphery of the planar heating element against a flange formed within the base of the vessel, and to deform a wall portion of the vessel so that it retains the sealing ring under sealing pressure. Again this results in a vessel which cannot be serviced if the heating element fails.

An alternative technique is described in EP-A-0 285 839. The vessel is formed with an internal flange near its base and the periphery of the planar heating element seats upon this flange and is urged into sealing contact with the flange by virtue of the provision of a central mounting stud on the element which is secured to a bottom cover of the vessel so as to give rise to a reaction force which pulls downwards on the heating element. This arrangement provides for serviceability of the heating element, but can suffer from the problem that the clamping force that is generated is insufficient to ensure an effective seal, particularly if the vessel is abused during its usage.

A similar problem can arise with the proposal made in our own British Patent Application No. 9524176.6.

Objects and Summarv of the Invention: Accordingly, it is the principal object of the present invention to overcome or at least substantially reduce the abovementioned problems.

In accordance with the present invention the abovementioned object is achieved by means of a heating element mounting arrangement in which screw-threaded studs are provided around the underside of the periphery of the heating element, a gasket seal of appropriate shape is fitted over the studs and between the studs and the element plate, the studs pass through holes provided in a flange around the base of the vessel and the arrangement is secured by fitting nuts to the studs. The flange may be an internal or external flange with respect to the vessel, depending on the design of the product.

Alternatively, the heating element could be provided with holes which register with the holes in the flange and the studs could be provided on a separate fixation ring. This would avoid the need to form fixing studs on the heating element which could be undesirable with a resistance track type of heating element.

More generally, therefore, the present invention provides an electrically powered water heating vessel having a planar heating element which is secured in the vessel by virtue of the vessel having a mounting flange which is apertured at a plurality of locations throughout its length and by virtue of the heating element being sealingly secured to the mounting flange by means of screw-threaded fastening means which pass through said apertures.

The above and further features of the present invention are set forth in the appended claims and will be explained in the following by reference to the accompanying drawings.

Description of the Drawings: Figure 1 shows an exploded perspective view of the mounting of a heating element to a vessel in accordance with the teachings of the present invention; and Figures 2A, 2B and 2C show, respectively, a partial cross-sectional view of the appliance of Figure 1, a partial side elevation view of the appliance and a partial side elevation view of a base unit for use with the appliance.

Detailed Description of the Embodiment: Referring first to the exploded view of Figure 1, the vessel in question is the vessel part of a cordless electrical water heating vessel which also comprises a base unit (see Figure 2C) which, as is well known, serves to power the appliance from the mains electrical supply, there being co-operating electrical connectors provided on the vessel part and on the base unit which come together to power the vessel heating element when the vessel part is properly seated on the base unit. In Figure 1, which views the underside of the vessel part, the heating element 1 is formed with four screw-threaded studs 2 which fit through holes 3 in a gasket seal 4 and then through registering holes 5 in a flange 6 formed in the bottom of the vessel 7 where they are secured by means of nuts 8, the assembly then being received in a vessel cover part 9.

The heating element 1 is of the kind aforementioned which comprises an aluminium plate 10 having a sheathed heating element proper 11 cast or clenched into its undersurface. Shown attached to the central part of the underside of the element is an element protector control 12 adapted to switch-off the electrical supply to the heating element in the event of the element temperature rising above a certain safe level; the element protector control 12 is an X-type control manufactured by us and is substantially as described in GB-A-2 283 156 with reference to Figure 1 thereof. Also affixed to the underside of the heating element 1 is the vessel connector inlet part 13 of a cordless connection system substantially as described in WO-A-946185 with reference to Figures 7 to 11 thereof. The method of fixing of the element protector control 12 and the connector inlet part 13 to each other and to the heating element 1 is described in our British Patent Applications Nos.

9522594.2 and 9607413.3.

Figure 2A is a partial cross-sectional view showing the assembled vessel of Figure 1, complete with element protector control 12 and connector inlet part 13, seated upon a base unit 14 which has affixed thereto a base unit connector part 15 complementary to the connector part 13 that is provided on the vessel.

The base unit connector part 15 is as described in WO-A-946185. Figure 2B is an external view of the appliance part of the cordless appliance of Figure 2A and Figure 2C shows the base part 14.

It will readily be appreciated from the foregoing that the heating element 1 is readily removable from the vessel simply by unscrewing the locking nuts 8 and can thus readily be replaced if it becomes faulty in use. The element protector control 12 and the connector inlet part 13 can also be arranged to be readily replaceable. Additionally, by the use of a plurality of fixing studs spaced around the periphery of the heating element, a uniform sealing force can readily be achieved.

Having thus described the present invention by reference to a specific embodiment, it is to be well understood that the described embodiment is exemplary only and that modifications and variations thereto are possible without departure from the spirit and scope of the invention.

Claims

CLAIMS:

1. An electrically powered water heating vessel having a planar heating element which is secured to the vessel by virtue of the vessel having a mounting flange which is apertured at a plurality of locations and by virtue of the heating element being sealingly secured to the mounting flange by means of screw-threaded fastening means which pass through said apertures.

2. A vessel is claimed in claim 1 wherein the heating element has a plurality of screw-threaded studs arranged to pass through the apertures of the vessel mounting flange.

3. A vessel as claimed in claim 1 or 2 including a gasket seal between the heating element and the vessel mounting flange.

4. A vessel as claimed in any of the preceding claims wherein the heating element comprises a metal plate having secured thereto a sheathed wire wound electrical resistance heating element.

5. A vessel as claimed in any of claims 1 to 3 wherein the heating element comprises an electrically insulating substrate carrying a resistance heating track.

6. A vessel as claimed in any of the preceding claims configured as a cordless appliance comprising a vessel part, a base part and electrical connector parts coupled to said parts for powering the heating element via the base part when the vessel part is seated upon the base part.

7. A vessel as claimed in any of the preceding claims wherein an element protector control is associated with the heating element for switching off the supply of electricity thereto in the event of the element temperature rising above a safe level.

8. An electrically powered water heating vessel substantially as herein described with reference to the accompanying drawings.