GB2363973A

GB2363973A - Securing planar heating element in liquid heating vessel

Info

Publication number: GB2363973A
Application number: GB0016050A
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: 2000-06-29
Filing date: 2000-06-29
Publication date: 2002-01-16
Also published as: AU2001274299A1; WO2002001992A1; GB0016050D0

Abstract

A liquid heating vessel such as a kettle or hot water jug has a planar heating element 1 secured therein by a variety of methods which accommodate dimensional variations of a glass vessel body. A first method uses a clamping ring 6 secured to the heating element 1 inside of a flanged opening in the vessel body to clamp the heating element periphery against the flange 3 with a sealing ring 5 therebetween. A second method (Figures 3 and 4) has a clamping ring (34) secured to a shaped flange (35) surrounding an opening in the vessel bottom and the clamping ring, by itself or in co-operation with other means, secures the heating element periphery to the flange with a seal (32) therebetween. A third method (Figures 5 and 6) has a depending flange (51) around an opening in the vessel bottom and an upwardly - directed flange (58) around the periphery of the heating element (57) so that when the heating element is juxtaposed with the vessel bottom the respective flanges locate adjacent to but laterally spaced from each other, and a seal (54) is provided in this spacing.

Description

2363973 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, urns, 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.

Background 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 GB-A-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 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 GB-A-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 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.

Objects and Summary 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, in one of its aspects, a planar heating element is secured in an opening in the base of a liquid heating vessel by provision of a flange around the opening, by abutting the heating element periphery against one side of such flange with a seal therebetween, and by urging the heating element periphery towards the flange so as to compress the seal by means of a clamp ring which is attached to the heating element inwardly of the flange and bears against the opposite side of the flange.

According to another of its aspects, the present invention provides a clamping ring which can be secured around a shaped rim surrounding an opening in the base of a vessel, the shaping of the rim in co-operation with the form of the clamping ring being such as to secure the clamping ring to the vessel, and the planar heating element is secured in the base opening of the vessel by use of the clamping ring either directly or in co-operation with other fixing means secured to the clamping ring.

According to yet another aspect of the present invention, the vessel has a downwardly depending rim surrounding an opening in the base thereof, the heating element has an upwardly extending rim which locates outside of the vessel rim with a spacing therefrom when the heating element is appropriately juxtaposed with the vessel, a seal is disposed within said spacing and means are provided to retain the heating element in place.

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

Description of the Drawings:

Figure 1 is a schematic cross-sectional view of an embodiment of the first abovementioned aspect of the invention; Figure 2 is a schematic cross-sectional view of another embodiment of the first abovementioned aspect of the invention; Figure 3 is a schematic cross-sectional view of an embodiment of the second abovementioned aspect of the invention; Figure 4 is a schematic cross-sectional view of another embodiment of the second abovementioned aspect of the invention; Figure 5 is a schematic cross-sectional view of an embodiment of the third abovementioned aspect of the invention; and Figure 6 is a schematic cross-sectional view of another embodiment of the third abovementioned aspect of the invention.

Detailed Description of the Embodiments:

Referring to Figure 1, the arrangement shown therein comprises a planar heating element 1 fitted into the bottom of a glass bodied water heating vessel 2 the heating element 1 bearing around its periphery against the upper side of an internal flange 3 provided around an opening 4 in the bottom of the vessel and a seal 5 being provided between the heating element 1 and the flange 3 To retain the heating element 1 in place with the seal 5 under compression, a clamp ring 6 is provided which is secured to the heating element 1 inwardly of the flange 3 by the provision of screw-threaded posts 7 depending from the underside of the heating element 1 which pass through holes 8 provided in the clamp ring 6 and can accept locking nuts (not shown).

The clamp ring 6 extends outwardly under the flange 3 of the vessel body and upwardly as shown into contact with the under side of the flange 3, with a protective plastics material moulding 9 located between the upper end of the clamp ring 6 and the under side of the flange 3 The plastics material moulding 9 can be omitted if the clamp ring 6 is itself made of plastics material, but is preferably provided when the clamp ring is formed of metal to reduce the possibility of heat from the heating element 1 being conducted by the clamp ring 6 to the glass vessel and possibly giving rise to undesirable thermal stresses A base 10 is fitted to the vessel by any convenient means.

Figure 2 shows an arrangement very similar to that of Figure 1 but employing a pressed metal clamp ring 6 ' which is provided with barbed press-fit holes 8 ' which fit onto plain studs 7 ' projecting from the underside of the heating element 1 ' to enable rapid assembly without need for screw-threaded fastenings The same reference numerals are used in Figure 2, with the addition of a prime, as are used in Figure 1 to designate like parts.

Figure 3 shows an alternative embodiment in which the glass bodied vessel 30 has an additional, outwardly directed, horizontal flange 31 projecting from the bottom of the base aperture A seal 32 having a special form fits over the periphery of the flange 31 and over the periphery of the planar heating element 33 A split clamping ring 34 fits around a downwardly projecting part 35 of the vessel aperture and is prevented from coming off by the abovementioned horizontal flange 31 and seal 32 when the screws holding the two halves of the clamping ring 34 have been tightened The clamping ring 34 is provided with holes 35 which are used to affix a base moulding 37 to the vessel body 30, the base moulding serving also to clamp the underside of the seal assembly 32 The E-section, specially formed seal 32 provides location to the sealing surfaces so that they do not move out of alignment during assembly, but if some other means of ensuring alignment were to be used then a simple washer form seal could be used.

Figure 4 illustrates a variation of the Figure 3 arrangement in which the split clamping ring 34 ' is formed with a tapering inner form, as shown, so that as it is tightened around the seal 32 ' it performs the dual function of compressing the seal 32 ' and supporting the heating element 33 ' in place In this embodiment the flange 31 ' is angled downwardly and outwardly, rather than being horizontal as in Figure 3, so as to complement the compression of the seal 32 ' The same reference numerals are used in Figure 4, with the addition of a prime, as are used in Figure 3 to designate like parts.

In Figure 5, yet another approach to the assembly of a planar heating element into a liquid heating vessel, particularly but not exclusively a glass bodied vessel, is illustrated In this arrangement, the vessel body 50 is open at its bottom, and has a depending flange or rim 51 surrounding the opening 52 with a seat 53 for an elastomeric seal 54 provided in the outer surface of the flange 51 The seal 54 is cross-sectionally shaped as shown to define a recess 55 and a plurality of blade-like elements 56 which extend outwardly The planar heating element 57 has a peripheral edge formed to define an upwardly-directed flange 58 terminating in an inwardly-directed rim 59 and, as illustrated, is dimensioned so that when the heating element 57 is fitted onto the bottom of the vessel body 50, the flange 58 closely parallels the flanged portion 51 of the vessel body so that the blade-like elements 56 of the seal 54 bridge the gap between the two parts and form an effective seal therebetween, and the rim 59 lodges in the seal recess 55 so as to retain the heating element The heating element flange 58 in this arrangement may be formed to have a degree of flexibility sufficient to ensure that the heating element can readily be snap-fitted over the bottom of the vessel body with the seal 54 received in its accommodating seat 53 in the depending flange 51, and to ensure in such an arrangement that the heating element cannot be accidentally displaced, a base cover part 60 for the vessel can be arranged to bear upon the outer surface of the heating element flange 58 or at least prevent it from displacing outwardly to a sufficient extent to disengage the heating element rim portion 59 from the seal recess 55.

Figure 6 shows a modification of the Figure 5 arrangement in which the planar heating element 57 ' is secured in place not by interaction with the seal 54 ' as in Figure 5, but rather by provision of a split clamping ring 70 which is secured to the depending vessel body flange 51 ', where it locates in an accommodating formation in the outer surface of the flange, and which serves as shown for the attachment of the base cover part 60 ' which in turn has an abutment portion 71 supporting the heating element 57 ' The same reference numerals are used in Figure 6, with the addition of a prime, as were used in Figure 5 to designate like parts.

The invention having been described in the foregoing by reference to specific embodiments, it is to be well understood that the embodiments are exemplary and that modifications and variations thereto are possible without departure from the spirit and scope of the invention as set forth in the appended claims For example, whereas the described embodiments have concerned glass bodied vessels, the same teachings could usefully be applied to plastics or metal, ceramics (porcelain) or earthenware bodied vessels.

Claims

CLAIMS:

1 A method of securing a planar heating element in an opening in the base of a liquid heating vessel, said method comprising providing a flange around said opening, abutting the heating element periphery against one side of said flange with a seal provided between the heating element and the flange, and urging the heating element periphery towards the flange by use of a clamp ring attached to the heating element inwardly of the flange and bearing against the opposite side of the flange.

2 A method as claimed in claim 1 comprising providing a protective layer between said opposite side of the flange and that part of the clamp ring which bears against the flange.

3 A method as claimed in claim 1 or 2 wherein the clamp ring is attached to the heating element by means of screw-threaded fasteners.

4 A method as claimed in claim 1 or 2 wherein the clamp ring is formed of metal and is provided with barbed press-fit holes which fit onto studs projecting from the heating element to attach the clamp ring to the heating element.

A liquid heating vessel having a planar heating element secured therein by a method as claimed in any of the preceding claims.

6 A method of securing a planar heating element in an opening in the base of a liquid heating vessel, said method comprising securing a clamping ring around a shaped rim surrounding said opening, the shaping of the rim in co-operation with the form of the clamping ring being such as to secure the clamping ring to the vessel, and securing the planar heating element in the vessel by use of said clamping rim.

7 A method as claimed in claim 6 wherein the clamping ring itself serves to secure the heating element in the vessel.

8 A method as claimed in claim 6 wherein the clamping ring has further fixing means affixed thereto for securing the heating element in the vessel.

9 A method as claimed in any of claims 6 to 8 wherein the shaped rim includes a flange portion, the heating element is arranged with its periphery juxtaposed with said flange portion with a seal therebetween, and the ring is secured, at least in part, by said clamping ring.

A method as claimed in claim 9 wherein said seal has a substantially E-shaped cross-section.

11 A liquid heating vessel having a planar heating element secured therein by a method as claimed in any of claims 6 to 10.

12 A method of securing a planar heating element in an opening in the base of a liquid heating vessel, said method comprising providing the vessel body with a downwardly depending rim surrounding said opening, providing the heating element with an upwardly extending peripheral rim having an inside diameter greater than the outside diameter of the vessel rim, juxtaposing the heating element with the vessel body so that the rim of the heating element locates outside of the vessel rim with a spacing therefrom and providing a seal in such spacing, and providing means to retain the heating element in place.

13 A method as claimed in claim 12 wherein for retaining the heating element in place the peripheral rim of the heating element has an inwardly directed portion which engages with the seal and/or the downwardly depending vessel rim.

14 A method as claimed in claim 12 wherein for retaining the heating element in place a clamping ring is provided around the downwardly depending rim of the vessel and fastening means are attached to said clamping ring to retain the heating element.

A liquid heating vessel having a planar heating element secured therein by a method as claimed in any of claims 12 to 14.

16 A liquid heating vessel as claimed in claim 5 or 11 or 15 wherein the vessel body is formed of glass or of a ceramics or earthenware material.

17 A liquid heating vessel as claimed in claim 5 or 11 or 15 or 16 wherein the heating element is a thick film heating element.

18 A method of securing a planar heating element in an opening in the base of a liquid heating vessel, said method being substantially as herein described with reference to any of the accompanying drawings.

19 A liquid heating vessel having a planar heating element secured therein by a method as claimed in claim 18.

A liquid heating vessel as claimed in claim 19 wherein the vessel body is formed of glass or of a ceramics or earthenware material.