WO2001093732A1

WO2001093732A1 - Improvements relating to liquid heating vessels

Info

Publication number: WO2001093732A1
Application number: PCT/GB2001/002356
Authority: WO
Inventors: Robert Andrew O'neill; John Anthony Howarth
Original assignee: Otter Controls Limited
Priority date: 2000-06-05
Filing date: 2001-05-25
Publication date: 2001-12-13
Also published as: GB0013686D0; GB2363055A; GB2363055B; AU5864001A

Abstract

A liquid heating vessel has a thick film heating element secured in place by virtue of the periphery of the thick film heating element having an elastomeric seal in the form of a simple rectangular cross-section, cylindrical, elastic band stretched around its periphery, and the heating element and seal then being pressed into a cup-shaped, accommodating formation that is provided in the vessel. A plurality of spring clips spaced about the heating element periphery ensure that the heating element is secured in the cup-shaped formation, the spring clips being clamped onto the heating element periphery and arranged to compress the seal around the heating element periphery when a bottom part of the vessel is attached.

Description

IMPROVEMENTS RELATING TO LIQUID

HEATING VESSELS

Field of the Invention:

This invention concerns improvements relating to liquid heating

vessels, particularly but not exclusively kettles and hot water jugs, and more

particularly concerns the mounting and sealing of planar heating elements,

particularly but not exclusively thick film heating elements, in such liquid

heating vessels.

Background of the Invention:

The steel from which thick film printed heating elements are made at

present is not the most suitable for forming the body of a steel kettle or jug,

because of its poor corrosion resistance and inferior formability. In addition it

is common for the heating element substrate to be thicker than 1mm, whereas

a jug body is typically 0.4mm or less, and making the body thicker would

increase the cost and difficulty of manufacture considerably. There is

therefore a need for a simple securing and sealing method to hold a thick film

heating element into the base of a steel vessel. One possibility is our

"Easifix" (GB-A-2 830 064), but the complexity of the seal form, which was

designed to compensate for the vagaries of plastic mouldings, is not justified

when used with a more compatible steel body. The Strix "Sureseal"

(GB-A-2 301434) could also be used, but he need for a final pressing

operation to form the wall of the upwardly facing peripheral groove adds to

the cost of this system, and the form of the heating element is more complex. Objects and Summary of the Invention:

It is thus the principal object of the present invention to overcome or at least substantially reduce the abovementioned problem.

According to the present invention, a generally planar disc-shaped

heating element is pressed into an accommodating formation which cups the heating element periphery and a seal is interposed between the heating element periphery and the cup formation. To ensure that the heating element is sufficiently well retained, for example so that it will not be displaced if the

vessel is dropped when filled with liquid, clips may if desired be provided at spaced apart locations around the heating element periphery.

An exemplary embodiment of the invention is described hereinafter in which a rubber seal of a simple cylindrical form, like a rubber band, is stretched around the edge of a flat disk-shaped heating element. This assembly is then pressed into a cup like formation in the base of the vessel,

the lip of which may be turned slightly inwards to assist retention. The formation on the base of the vessel may simply be pressed into the steel

during forming, the superior formability of a 300 series stainless steel helping

here. Unlike the groove formation of the "Sureseal", which has to be formed

onto the element substrate, this cup form does not form any part of the

manufacture of the element itself. Sealing is effected by the simple

compression of the rubber ring, and by suitable sizing of the ring, of the

heating element diameter and of the inside diameter of the cup formation. If

the fit is tight enough it may be sufficient in itself to retain the element in place, but it is preferred as abovementioned to add a number of clips which fit

over the cup wall and act to grip the seal when tightened.

The above and further features of the present invention are set forth in

the appended claims and will be made clear from consideration of the

following detailed description which is given with reference to the accompany

drawings.

Description of the Drawings:

Figure 1 is a side elevation view showing the bottom part of a liquid

heating vessel;

Figure 2 is a cross-sectional view on the line B...B in Figure 1 ;

Figure 3 is an enlargement of that part of Figure 2 which is bounded

by the circle C;

Figure 4 shows the seal arrangement only of Figure 3; and

Figure 5 shows the clip that is used to retain the heating element in

perspective view.

Detailed Description of the Embodiment:

The embodiment that is illustrated in the accompanying drawings is a

plastics bodied water heating kettle or jug in which a thick film heating

element is secured within an annular mounting by means of the present

invention and the annular mounting is, in turn, secured in the vessel body by

means of our "Easifix" invention which is the subject of GB-A-2 330 064. It

is however to be appreciated that the annular mounting, or at least the part

thereof that co-operates with the heating element, could be formed integrally with a stainless steel vessel body or could be attached thereto in a separate operation.

Referring to Figures 1 and 2 and the enlarged showing of Figure 3, a plastics material jug body 1 has a stainless steel cover section 2 which bridges

the join between the body 1 and a plastics material jug bottom 9. A thick film heating element 8 is secured in the vessel by means of a stainless steel mounting ring 5 which in turn is secured in the vessel by the Otter "Easifix"

method, the "Easifix" seal being designated 3 and the "Easifix" circlip being designed 4. Reference may be made to GB-A-2 330 064 for a full description of the "Easifix" system. A seal 7 which is in the form of a simple rectangular cross-section, cylindrical member (like a rubber band) is stretched around the

periphery of the heating element 8 and the heating element 8 with its seal 7 fits tightly into a cup-shaped formation 11 provided in the mounting ring 5. As will be explained in more detail in the following, the vessel bottom 9 is

secured in place by means of a plurality of screw fittings (not shown) which

locate in cylindrical posts 12 and co-operate with spring metal clips 6 which

engage with the heating element mounting ring 5 and also, when the screw

fittings are tightened, serve to retain the heating element 8. A schematically illustrated heating element overtemperature protection control cum 360°

connector inlet 10 is secured between the heating element 8 and the vessel

bottom 9 and might, for example, comprise one of Otter Controls X4 series

controls which are substantially as described in WO-A-9954903. As shown most clearly in Figure 4, the heating element mounting ring

5 has a substantially vertical outer wall 13 with an outwardly-turned flange 14

at its bottom end, these being provided for co-operating with the "Easifix"

seal 3. At its upper end, the wall 13 turns inwardly and downwardly so as to

define an inwardly sloping surface 15 which, at its innermost edge turns

downwardly and then reverses upon itself and curves downwardly at 16, 17

and 18 respectively to define the cupping formation 11 which engages with

the heating element 8 and its seal 7. If desired, the vertically depending part

18 could curve inwardly by a small amount insufficient to present any

difficulty as regards insertion of the heating element 8 and seal 7.

The spring fixing clip 6 is shown in Figure 3 in relaxed condition, ie.

prior to tightening of the fixing screw, and in Figure 4 in tightened condition,

ie. after tightening of the fixing screw. Figure 5 is an enlarged perspective

view of the clip. As shown, the clip 6 has a hooked portion 19 which is

shaped complementarily to the parts 16, 17 and 18 of the mounting ring 5 so

as to engage with the mounting ring 5 as shown in Figure 4. The hooked

portion 19 connects to a generally horizontal portion 20 via a U-shaped part

21 which, as explained hereinafter, acts as a stop abutment. The horizontal

portion 20 has an opening 22 for engagement with the fixing screw. A further

horizontal portion 23 underlies the portion 20 and has an opening 24

underlying the opening 22 and sized to provide clearance from the fixing

screw. The portion 23 is a cantilever and at its free end has an upwardly and inwardly bent portion 25 which terminates with a small spacing from the shank of the hooked portion 19.

With the heating element 8 and seal 7 engaged with the cupping portion 11 of the heating element mounting ring 5, the fixing clips 6 can be

placed as shown in Figure 3, it being appreciated that the mounting ring 5 need not be assembled with the vessel at this stage. Using the "Easifix" system, the heating element/seal/mounting ring/clips sub-assembly may then be inserted into the vessel. The base 9 is then fitted, any adjustment of the

clips 6 that might be necessary to ensure their proper registry with the posts 12 of the vessel bottom 9 being readily accomplished by sliding them around the fixing ring 5. When the fixing screws are inserted and tightened, the cantilever portion 23 of the spring clips is urged upwardly into abutment with the bottom of the U-shaped part 21 and the portion 25 moves into compressing contact with the bottom edge of the seal 7 so as to deform it

under the edge of the heating element 8 as shown in Figure 4.

The invention having been described in the foregoing by reference to a

specific embodiment, it is to be well understood that the embodiment is in all

respects 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 invention has been described in

the foregoing by reference to the mounting of a thick film heating element in a

vessel, other kinds of generally planar heating elements could be assembled

with vessels in the same manner; for example another kind of heating element which can be fitted in accordance with the teachings of the present invention comprises a plate having clamped or otherwise assembled to the underside thereof an otherwise conventional sheathed heating element.

Claims

Claims:

1. A liquid heating vessel having a generally planar heating element

assembled with the vessel by virtue of the planar heating element being pressed into a formation which cups the heating element periphery with an

elastomeric seal interposed.

2. A liquid heating vessel as claimed in claim 1 wherein the heating element is a thick film heating element.

3. A liquid heating vessel as claimed in claim 1 or 2 wherein the heating element is assembled with a mounting ring having said formation.

4. A liquid heating vessel as claimed in claim 3 wherein the mounting ring is formed integrally with the vessel body or is permanently attached

thereto.

5. A liquid heating vessel as claimed in claim 3 wherein the mounting

ring is a separate component which is assembled with the vessel, sealing

means being provided between the mounting ring and the vessel.

6. A liquid heating vessel as claimed in any of the preceding claims

wherein the elastomeric seal is a substantially cylindrical member (like an

elastic band).

7. A liquid heating vessel as claimed in any of the preceding claims

wherein a plurality of spring clips are spaced around the periphery of the

heating element and serve to retain the heating element in engagement with

said formation.

8. A liquid heating vessel as claimed in claim 7 wherein the clips further

serve to compress the seal around and under the heating element at the clip

locations.

9. A liquid heating vessel as claimed in claim 7 or 8 wherein the

formation has a portion which overhangs the periphery of the heating element

and the clips have portions which underlie the periphery of the heating

element.

10. A liquid heating vessel as claimed in claim 9 wherein the clips can be

tightened so as to compress the periphery of the heating element between said

overlying and underlying portions.

11. A liquid heating vessel as claimed in claim 10 wherein tightening of

the clips is effected by means of screw fittings serving to secure a bottom part

onto the vessel.

12. A liquid heating vessel substantially as herein described with reference to the accompanying drawings.

13. A spring clip for use in a liquid heating vessel as claimed in any of

claims 7 to 12.