WO2002001992A1

WO2002001992A1 - Improvements relating to electrically heated vessels

Info

Publication number: WO2002001992A1
Application number: PCT/GB2001/002749
Authority: WO
Inventors: Robert Andrew O'neill; Antonio Martin Gaeta; Peter Hallam Wright
Original assignee: Otter Controls Limited
Priority date: 2000-06-29
Filing date: 2001-06-21
Publication date: 2002-01-10
Also published as: GB2363973A; AU2001274299A1; GB0016050D0

Abstract

A liquid heating vessel (2,2') such as a kettle or hot water jug has a planar heating element (1,1') secured therein by a variety of methods which accommodate dimensional variations of a glass vessel body (2,2'). A first method uses a clamping ring (6,6') secured to the heating element (1,1') inside of the flanged opening in the vessel body (2,2') to clamp the heating element periphery against the flange (3,3') with a sealing ring (5,5') therebetween. A second method has a clamping ring (34,34') secured to a shaped flange (31,31') surrounding an opening in the vessel bottom and the clamping ring (34,34'), by itself or in co-operation with other means, secures the heating element periphery to the flange (31,31') with a seal (32,32') therebetween. A third method has a depending flange (51,51') around an opening in the vessel bottom and upwardly-directed flange (58,58') around the periphery of the heating element (57,57') so that when the heating element (57,57') is juxtaposed with the vessel bottom the respective flanges locate adjacent to but laterally spaced from each other, and a seal (54,54') is provided in this spacing.

Description

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 aπangement 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.

5. 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.

10. 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.

15. 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.

20. A liquid heating vessel as claimed in claim 19 wherein the vessel body

is formed of glass or of a ceramics or earthenware material.