IMPROVEMENTS RELATING TO ELECTRICALLY HEATED VESSELS

Abstract: An electrically heated water boiling vessel (1) has a planar heating element (8) secured therein by virtue of the heating element having attached to the underside thereof an integrated element protector control (for protecting the heating element against overheating) and 360 DEG cordless connector component (14) which in turn is secured to the bottom of the vessel. The heating element with the control/connector attached thereto is introduced into the vessel through the top thereof and is pushed down inside the vessel until the heating element engages abutment ribs provided in the bottom of the vessel. The control/connector is then secured by screw fastenings (17, 18) to the vessel bottom. A sealing ring (11) encircles the periphery of the heating element and provides a liquid-tight seal between the heating element and the vessel interior.

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: Our British Patent Application No. 9821862.1 concerns the assembly of planar electric heating elements into the bodies of electrically heated vessels and further arrangements are disclosed in our British Patent Application No. 9826969.9. Planar heating elements are commonly of two different types, namely the underfloor heating element which comprises a metal plate having a sheathed heating element clamped or clenched to the underside thereof or otherwise incorporated into the heating element structure (as for example in a die cast heating element), and the thick film heating element which comprises a resistance heating track or layer formed on the underside of an electrically insulating substrate comprised, for example of stainless steel which is coated with glass or other electrically insulating material, the resistance heating track or layer being formed on the surface of the glass and a further, protective, electrically insulating layer being formed over the resistive heating track or layer. As described in British Patent Application No. 9821862.1 abovementioned, a kettle or jug having a planar heating element can have the heating element secured to the bottom of a vessel body moulding of plastics material which is open at its bottom end to accommodate the heating element. A further plastics material moulding is required to cover the heating element and secure it in place and also to cover the electrical parts. Other such arrangements are described in WO-A-9618331 (Strix) and EP-A-0 807 394 (Tefal). One advantage of the arrangements described in our British Patent Application No. 9821862.1 is that they allow freedom of design of the vessel body and, in particular, allow the top of the vessel to have a smaller section than the bottom without necessitating complex mould cavity constructions and unsightly thick sections at the lower end of the vessel. In our British Patent Application No. 9826969.9 the teaching of our British Patent Application No. 9821862.1 is modified for application to glass bodied vessels where different problems apply. Objects and Summary of the Invention: The present invention provides a departure from the teachings of our British Patent Applications Nos. 9821862.1 and 9826969.9 abovementioned for use in situations where design freedom as abovementioned is not a requirement, for example in the manufacture of a budget kettle, and where the top of the vessel body can be at least the same section as the bottom. The invention is applicable also to vessels as abovementioned but wherein some degree of design freedom is retained by forming the top of the vessel body in two parts one of which, as abovementioned, has at least the same action as the vessel bottom and the other of which, constituting the top of the vessel, can have a reduced section. According to the present invention a vessel body is provided where the top section of the body is the same as or larger than the bottom section so that the heating element can be introduced into the vessel through the top section, and where a seating for the element is provided in the bottom section, sealing of the element with respect to the vessel body being provided for at the junction of the heating element periphery with the internal wall of the vessel body and/or with the seating. In a first embodiment of the invention which is described in detail hereinafter, a jug body moulding is formed with an integral base formed with a central circular opening for accommodating a 360° cordless connector component enabling the vessel body to be seated upon a base incorporating a complementary electrical connector component in any relative rotational orientation of the vessel body and base. An exemplary 360° cordless connector set is described in WO-A-9406185 and is available from us as our CS4/CP7 cordless connector set. A plurality of element support and location ribs are provided within the vessel body to provide a seating for a planar heating element introduced through the top of the body and pushed down onto the upper surfaces of the ribs. Sealing of the heating element is effected by use of an annular sealing ring which encircles the periphery of the heating element and has a plurality of radially outwardly extending flanges or fins which are resiliently deformed by contact with the vessel body. As described in our British Patent Application No. 9808484.1, the 360° cordless connector component can be integrated with heating element overtemperature protection devices and can be arranged for attachment to the underside of the heating element and, in the present embodiment, provision is additionally made for securing the integrated 360° connector cum heating element protector device to the bottom of the moulded plastics vessel, the connector/protector device thus constituting a structural element which, by virtue of its attachment to the bottom of the vessel, serves to hold the heating element in place against the upper surfaces of the element support and location ribs. In accordance with another embodiment which is also described in detail hereinafter, the annular sealing ring is provided about the periphery of a support moulding which is designed to sit in the bottom of the vessel and the planar heating element is placed on top of the upper surface of the support moulding, a portion of the sealing ring extending between the support moulding and the underside of the heating element. As with the first-mentioned embodiment, the heating element is arranged to be pulled down into the vessel, for example as in the first embodiment the heating element is pulled down onto the support ribs, and this compresses the portion of the sealing ring which extends between the support moulding and the heating element. By virtue of the arrangement of this embodiment, a completely flat heating element can be employed, the underside of the element being sealed with respect to the upper surface of the support moulding and the circumferential periphery of the support moulding being sealed radially with respect to the internal wall of the vessel. In both of the abovementioned embodiments, a planar heating element of lesser diameter than the internal diameter of the vessel can be utilized by sealingly securing the heating element in an annular support ring and sealingly securing the support ring into the vessel in accordance with the teachings of the present invention. The invention is not limited to vessels of uniform cross-section throughout their height. A planar heating element can be fixed into a uniform section vessel bottom part according to the teachings of the invention and then an upper part of the vessel can be affixed to and on top of the vessel bottom part. The design of the vessel upper part is thus limited only by the need to interface at its lowest section with the uppermost section of the bottom part of the vessel and otherwise places no limitations on the vessel designer. The above and further features of the present invention are set forth in the appended claims and, together with advantages thereof, will be explained hereinafter by reference to exemplary embodiments shown in the accompanying drawings. Description of the Drawings: Figure 1 shows a cut-away perspective view of a vessel body moulding of a first embodiment of the present invention; Figure 2 is a cross-sectional view showing a heating element assembled into the vessel body moulding of Figure 1 according to the teachings of the present invention; Figure 3 shows an alternative way of securing a planar heating element into a vessel body moulding as in Figure 1 ; Figure 4 shows a modification of the arrangement of Figure 3 enabling a smaller diameter heating element to be employed; and Figure 5 shows yet another way in which a planar heating element can be secured into a vessel body. Detailed Description of the Embodiments: Referring to Figure 1, the present invention is particularly concerned with the securing of a planar heating element into a vessel body wherein the top section (above the heating element) is the same size as or larger than the bottom section (below the heating element) so that the heating element may be introduced via the top of the vessel, and can be pushed down to sit at a sealing location in the bottom of the vessel. Figure 1 shows a cut-away view of a vessel moulding in accordance with this proposal. The vessel body 1 has plain vertical walls 2 extending from an integral horizontal base 3 and a plurality of ribs 4 (only two of which can be seen) are provided within the vessel body 1, the ribs 4 defining with their uppermost surfaces a seating for the heating element. The base or bottom 3 of the vessel body 1 is formed with a central opening 5 for accommodating the 360° cordless connector part of a connector/element protector control such as the Otter Controls' X4 control which is described in our British Patent Application No. 9808484.1. Four bosses 6 are provided around the opening 5 and serve for mounting the connector/element protector control into the bottom of the vessel by means of screw-threaded fasteners. An opening 7 in the side wall 2 of the vessel body 1 provides access below the level of the heating element, once affixed, to the base compartment of the vessel for wires interconnecting with, for example, a remotely sited steam-sensitive control, located for example in a handle of the vessel and arranged to switch off the supply of electricity to the heating element in response to the generation of steam when water boils in the vessel. In an alternative cordless vessel having a more conventional non-360° connector set, the opening 7 could provide for connecting the vessel-mounted connector part to the heating element and it could serve a similar function in a corded vessel. Figure 2 is a cross-sectional view showing a planar heating element mounted into a vessel body as shown in Figure 1. The heating element 8 shown is a thick film heating element as aforementioned, but could be any form of planar or concealed heating element. The heating element 8 has a resistance heating portion 9 on its underside and, radially outside of the resistance heating portion 9, has an annular formed rim 10 which provides a mounting for a temperature resistant elastomeric ring seal 11. More particularly, the radially outermost surface 12 of the formed rim 10 has a vertical face and a short outward projection at its bottom edge and the sealing ring 11 is a close (stretched) fit about the surface 12 and has a groove complementary to the projection at the bottom edge of the heating element rim 10 for securely and correctly locating the seal 11 about the periphery of the heating element 8. The other circumference of the seal 11 has a plurality of circumferential fins 13 which, when the heating element 8 and seal 11 are fitted into the vessel by being pushed down onto the tops of the support ribs 4 are deformed upwardly as shown. The fins 13 are thin enough to deform as the heating element is assembled into the vessel, but are sufficiently stiff and resilient to follow the internal profile of the vessel wall 2 and not only make an effective seal therewith, but also maintain the seal during any subsequent movement caused, for example, by temperature change. Also shown in Figure 2 is an X4 cordless connector/control 14 which is secured to the undersurface of the heating element 8, for example in the manner described in our British Patent Application No. 9808484.1. When the heating element 8 and attached X4 control 14 is mounted into the vessel body 1 and pushed down into place with the rim 10 of the heating element 8 located on the upper ends of the support ribs 4 with the lowermost horizontal part 15 of the seal 11 between the two, the 360° connector part 16 of the X4 engages with the aperture 5 in the bottom 3 of the vessel body and the bosses 6 register with bores 17 provided in a moulded plastics body part of the X4 control 14 so that fixing screws 18 can be inserted and tightened. By this means the X4 control is pulled down towards the bottom of the vessel 1 and so the heating element 8 is pulled down into secure engagement with the tops of the support In the arrangement of Figure 2, the rim 10 of the heating element could be inverted as compared with the illustrated rim so long as care was taken when assembling the heating element into the vessel body to ensure that the seal 11 did not slip out of proper engagement with the outermost face 12 of the rim 10. Such an arrangement might be advantageous in that it would ensure that in the event of the vessel boiling dry a quantity of water would remain in the trough defined by the upturned rim 10 and would protect the seal 11 from any resultant overheating of the heating element 8 until such time as the X4 control operated. Figure 3 shows a further embodiment of the present invention which in principle is the same as the embodiment just described but employs a completely flat heating element 20 which is supported, with sealing, on a separate support ring 21 which provides a mounting for a heat-resistant elastomeric sealing ring 22 and seats upon the support ribs 4. In this alternative embodiment, the support ribs 4 could be made integral with the support ring 21 rather than as part of the vessel body 1, or alternatively the ribs 4 could be omitted and a longer (in the vertical direction) support ring utilized. Referring to Figure 3, the support ring 21 is simply an annular member of rectangular cross-section which underlies the periphery of the heating element 20 for supporting the same on the rubs 4. The ring seal 22 is similar in many respects to the seal 11 of the first embodiment but has a portion 23 which locates between the underside of the heating element 20 and the upper surface of the support ring 21. The seal portion 23 may have formations as shown on its upper surface to enhance its performance against the underside of the heating element 20. The seal 22 and the support ring 21 may be integral with each other, for example by being formed together in a twin shot moulding, to simplify assembly, or alternatively and to reduce the cost the support πng 31 may simply be a length cut from an extruded tube. In all other respects the second embodiment reflects the teachings of the first embodiment. The X4 control 14 is secured to the heating element 20 and when the fixing screws 18 are tightened the heating element 20 is pulled down towards the upper surface of the sealing ring 21 thereby compressing the seal portion 23 therebetween and ensuring a satisfactory seal therebetween. Sealing of the heating element 20 with respect to the vessel body is effected by virtue of the sealing between the support ring 21 and the vessel body, achieved by the fins 13 of the ring seal 22, and the sealing just mentioned between the support ring 21 and the heating element 20. Figure 4 shows yet another embodiment which represents a modification of the Figure 3 embodiment to enable a smaller diameter heating element 30 to be accommodated. As shown, the moulded plastics vessel body 1 is provided at its lower end with an internal flange 31 which supports a downwardly-extending wall 32 terminating in a horizontal web 33 which performs much the same function as the vessel bottom 3 in the previously-described embodiments, namely provides a mounting for an X4 control as aforementioned. To conceal the reduced diameter region constituted by the elements 31, 31 and 33, a cosmetic skirt 34 is moulded integrally with the vessel body 1 and continues the profile of the body to below the level of horizontal web 33 to provide stability to the vessel. A further embodiment is shown in Figure 5 which has similarities to the arrangement of Figure 4, in respect of the provision of elements 31, 32 and 32 integrally moulded within the vessel body 1, but employs an alternative form of thick film heating element and an alternative seal arrangement. As shown, the heating element 40 has a rim portion 41 similar in shape to the rim 10 of the heating element 8 of the first embodiment but of smaller size, the rim 41 defining a downwardly facing groove around the periphery of the heating element. The vessel body moulding is formed with a complementarily shaped integral upstand 42 which is dimensioned and arranged to fit within the downwardly facing groove on the heating element 40 when the latter is assembled into the kettle body. A simple ring seal 43 is seated within the groove as shown. As with the previously described embodiments, and X4 control 14 is mounted to the underside of the heating element 40 and is affixed by screws to the web 33. As the screws are tightened, so the seal 43 is compressed. Support ribs 4 are shown in Figure 5 and perform no function in the arrangement shown. However, the ribs 4 could be extended upward so as to limit the downwards movement permitted to the heating element 40 as the fixing screws are tightened, this preventing the seal ring 43 from being over-compressed and possibly extruded out of position. The principal advantages of the aforementioned arrangements reside in their simplicity and inexpensiveness. At its simplest, the present invention is well adapted to low cost vessel designs and enables a vessel to be provided with a planar heating element, which is per se more expensive than a conventional sheathed type immersion heating element, at a cost which is competitive with vessels having conventional sheathed type immersions heating elements. Variations and modifications of the described embodiments will occur to those possessed of appropriate skill and knowledge without departure from the spirit and scope of the invention as set forth in the appended claims. For example, whereas the invention has been described in the foregoing by reference to vessel bodies of uniform cross-section which enable the heating element to be assembled with the vessel through the top opening of the vessel, the invention has wider application. The arrangements described could relate to the mounting of a planar heating element into a bottom part only of a vessel body and an upper part, which could be of any desired shape, could subsequently be secured on top of the bottom part. Exotically shaped vessel bodies could readily be accommodated in this way. Furthermore, while the invention has been described in the foregoing by reference to plastics bodied vessels, the teachings of the invention could similarly be applied to glass vessel bodies or to vessel bodies formed of ceramics, porcelain or china. Finally, whereas the invention has been described by reference to cordless vessels provided with 360° cordless connector sets, for example the Otter Controls' CS4/CP7 system, the invention is equally applicable to more conventional non-360 0 cordless vessels and to corded vessels.

Claims: CLAIMS: 1. An electrically heated vessel having a planar heating element secured therewithin by virtue of the planar heating element being pulled down into engagement with abutment means in the vessel by a structure affixed to the bottom of the vessel. 2. A vessel as claimed in claim 1 wherein the structure that is affixed to the bottom of the vessel is a thermally-sensitive control device and/or a cordless connector component. 3. A vessel as claimed in claim 2 wherein the cordless connector component is a 360° connector component accessible by a complementary connector component through an opening in the bottom of the vessel. 4. A vessel as claimed in any preceding claim formed of plastics material, or formed of glass, ceramic, porcelain or china. 5. A vessel as claimed in any of the preceding claims wherein the abutment means is formed integrally with the vessel. 6. A vessel as claimed in any of claims 1 to 4 wherein the abutment means is a component non-integral with the vessel which is placed into the bottom of the vessel prior to introduction of the heating element. 7. A vessel as claimed in any of the preceding claims wherein sealing means operates between the periphery of the heating element and the internal wall of the vessel. 8. A vessel as claimed in claim 7 wherein the sealing means comprises a ring seal of elastomeric material extending around the periphery of the heating element, the ring seal having one or more outwardly extending circumferential fins engaging the internal wall of the vessel. 9. A vessel as claimed in any of claims 1 to 6 wherein the heating element engages a support ring and sealing means operates between the heating element and the support ring and also operates between the outer periphery of the support ring and the internal wall of the vessel. 10. A vessel as claimed in claim 9 wherein the sealing means comprises a ring seal of elastomeric material extending around the outer periphery of the support ring, the ring seal having one or more outwardly extending circumferential fins engaging the internal wall of the vessel. 11. A vessel as claimed in any of the preceding claims having a reduced cross-section portion formed in its base and wherein the heating element is located within the reduced cross-section portion. 12. A vessel as claimed in any of the preceding claims formed so as to permit the heating element to be assembled into the vessel through an opening in the top thereof. 13. A vessel as claimed in any of the preceding claims which is formed in at least two parts, namely an open bottom part enabling the heating element to be assembled into the bottom part of the vessel through the opening thereof and a top part secured to the bottom part. 14. A vessel as claimed in claim 13 wherein the top part of the vessel has at least one cross-section smaller in size than the heating element. 15. A vessel as claimed in any of the preceding claims wherein the heating element is a thick film heating element, or wherein the heating element comprises a metal plate having a sheathed heating element clamped or clenched to the underside thereof, or wherein the heating element comprises a die cast metal body having a heating element incorporated therein. 16. A vessel as claimed in any of the preceding claims wherein the bottom of the vessel is integral with the vessel side walls. 17. A method of manufacturing an electrically heated water boiling vessel, said method comprising: forming a vessel body moulding having a bottom wall integral with side walls and an open top; providing abutment means within said vessel body moulding, said abutment means defining a seating for assembly of a planar heating element into the vessel body moulding; forming a sub-assembly comprising a planar heating element and at least one of an overtemperature protection device and an electrical inlet connector for the heating element, said planar heating element being sized to be insertable into the open top of the vessel body moulding; providing sealing means adapted to seal the planar heating element with respect to the vessel body moulding when said sub-assembly is introduced into the vessel body moulding; introducing said sub-assembly into the vessel body moulding through the open top thereof with the sealing means in operative position; and securing said overtemperature protection device/electrical inlet connector to the bottom wall of the vessel body moulding so as to urge the planar heating element against said seating. 18. An electrically heated water boiling vessel, comprising: a vessel body moulding having a bottom wall integral with side walls and an open top; abutment means within said vessel body moulding, said abutment means defining a seating for assembly of a planar heating element into the vessel body moulding; a sub-assembly comprising a planar heating element and at least one of an overtemperature protection device and an electrical inlet connector for the heating element, said planar heating element being sized to be insertable into the open top of the vessel body moulding and locating on said seating; sealing means sealing the planar heating element with respect to the vessel body moulding; and means securing said overtemperature protection device/electrical inlet connector to the bottom wall of the vessel body moulding so as to hold the planar heating element against said seating.

Inventors: HOWARTH JOHN ANTHONY, O'NEILL ROBERT ANDREW, HOWARTH, JOHN, ANTHONY, O'NEILL, ROBERT, ANDREW
Applicants: HOWARTH JOHN ANTHONY, ONEILL ROBERT ANDREW, OTTER CONTROLS LTD, HOWARTH, JOHN, ANTHONY, O'NEILL, ROBERT, ANDREW, OTTER CONTROLS LIMITED
Application year: 2000
Main classification: A47J27
IPC codes: A47J27