GB2307602A

GB2307602A - Mounting protection control and connector of appliance heater

Info

Publication number: GB2307602A
Application number: GB9624664A
Authority: GB
Inventors: Robert Andrew O'neill; Ian Geoffrey White; Stephen Roger Brook
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 1995-11-27
Filing date: 1996-11-27
Publication date: 1997-05-28
Anticipated expiration: 2016-11-27
Also published as: HK1014625A1; CN1226142A; GB2307602B; AU2011497A; CN1135091C; WO1997019627A1; GB9624664D0; CA2238813A1; EP0869730A1; GB9524176D0

Abstract

A cordless electrical appliance 10 such as an electrical kettle has an element protection control 1 and an appliance power connector 4, the element protection control 1 and the appliance connector 4 being separate items which are coupled to respective ends of an elongate mounting bracket 18. The mounting bracket is affixed to the underside 16 of a planar heating element 12 by stud formations 17. By virtue of this arrangement the number of formations 17 provided on the planar heating element 12 can be minimized.

Description

IMPROVEMENTS RELATING TO ELECTRICALLY POWERED LIOUID RATING APPLIANCES AND CONTROLS THEREFOR Field of the Invention: This invention concerns improvements relating to electrically powered liquid heating appliances and controls therefor. The present invention may be applied to liquid heating appliances such as electric kettles, hot water jugs, urns, pans, laboratory equipment etc., and in the following the invention will be described with reference to electric kettles and hot water jugs though it is to be understood that the invention is not limited to such appliances.

Background of the Invention: In the field of electric kettle design, there has been a recent move away from the use of conventional metal sheathed heating elements to using planar heating elements. Planar heating elements have previously been incorporated into metal bodied appliances without undue difficulty, for example by forming the element as a bottom wall of the metal liquid heating vessel. With the widespread availability of lighter and cheaper plastics materials, plastics moulded liquid heating appliances have become popular. However, the incorporation of a planar heating element in such appliances has been more complicated.

In European Patent EP 0 285 839 there is described a kettle having a moulded plastics body and incorporating a planar heating element as a bottom wall of the liquid heating vessel. The planar heating element is supported on a projecting ledge of the plastics body and has a large downwardly projecting pillar at the centre of its lower face. The element is clamped against a seal by securing a moulded bottom cover, which has a clamping flange around its periphery for engaging the projecting ledge, to the downwardly projecting pillar with a nut. An element protection control, for switching off the appliance in the event of an overtemperature condition arising at the heating element, is provided on the underside of the planar heating element and is wired to a power connector at the side of the appliance.This design is not suitable for cordless appliances and the central pillar prevents the desirable positioning of the power connector at the centre of the kettle base.

It is also known from International Patent Application W094/18807, to provide a planar heating element mounted on an integral element protection control and power connector provided in an opening of a base wall of an appliance. The element is held in place by fasteners which pass through holes in the integral protection control and power connector and which are secured in the heating element. A sealing ring is provided between the raised planar element and the base wall to provide a watertight seal. A problem with such an arrangement is that it has among other things an overhanging element which is difficult to clean and an increased minimum water volume to be heated.In addition, such an arrangement lacks flexibility, the integration of the element protection control with the power connector limiting the ability of the appliance designer to design appliances with freedom and furthermore, imposing severe tolerance constraints upon the manufacturers of such appliances.

Recently, there has been produced a cordless electric kettle incorporating a flat heating element.

Cordless appliances have power supplied to the appliance proper via a base unit, the appliance proper and the base unit having complementary electrical connector parts adapted to come together to provide appropriate electrical connections through the base unit to the heating element in the appliance proper when the latter is seated on the base. An element protection control is mounted directly onto the underside of the element by fixing formations on the element. In addition, an appliance power connector is indirectly mounted onto the element via a metal mounting bracket. A moulded plastics bottom cover of the kettle is held in place by screws which pass through mounting holes of the connector, through holes in the bracket and which are screwed into a specially formed plastics moulding that is provided between the connector and the element.The construction of this kettle requires two separate mounting operations to secure the control and connector to the heating element. In addition, two additional flexible cables are required to make the electrical connections.

These cables are quite expensive, being insulated with high temperature resistant insulation.

Objects and Summarv of the Invent ion: An object of the present invention is to overcome or substantially reduce at least some of the aforementioned problems.

According to the present invention, in one of its aspects, there is provided a combination of an element protection control and an appliance power connector which are each coupled to a mounting bracket for mounting to a heating element of the appliance.

The provision of a mounting bracket is advantageous over the known arrangements because it enables both the element protection control and the appliance power connector to be affixed to the heating element at a single location. Accordingly, separate mounting studs or the like need not be provided on the heating element for each of the control and the connector as in the conventional arrangements.

Furthermore, the provision of the mounting bracket enables the assembly of the kettle to be simplified with the mounting of the control and connector being carried out in a single operation.

The mounting bracket preferably includes means for accommodating small differences in the mounting position of the appliance power connector relative to the heating element. More specifically, the accommodating means may for example comprise an elongate through-hole in the mounting bracket for cooperating with a threaded fastener over a range of different positions. This feature provides for greater positional tolerance between mounting formations on the heating element to which the mounting bracket is fixed and mounting formations on a bottom cover of the appliance which may be affixed to the connector.

The present invention also extends to an electrically powered heating appliance comprising a liquid heating vessel and a bottom cover and including an element protection control, an appliance power connector and a mounting bracket according to the teachings hereof. The invention is particularly, though not exclusively, applicable to liquid heating appliances wherein the electrical heating element of the appliance is of the planar type, for example as is described in British Patent Application GB-A-2 283 155.

The above and further features of the present invention are set forth with particularity in the appended claims and together with the advantages thereof will become clear from consideration of the following detailed description of an exemplary embodiment of the invention which is illustrated in the accompanying drawings.

Description of the Drawings: Figure 1 is a perspective view of an element protection control generally in accordance with the teachings of GB-A-2 194 099 and GB-A-2 248 724, specifically in accordance with the teachings of British Patent Application GB 9522594.2 a copy whereof is appended as an integral part hereof and as used in the hereinafter described exemplary embodiment of the present invention; Figure 2 is a perspective view of an appliance power connector in accordance with the teachings of W094/06185, specifically in accordance with the teachings of the abovementioned and appended British Patent Application No. 9522594.2 and as used in the hereinafter described exemplary embodiment of the present invention; and Figure 3 is a part sectional, part cut-away side elevation view showing the element protection control of Figure 1 and the appliance power connector of Figure 2 connected together and to a mounting bracket serving additionally for mounting a heating element in a liquid heating appliance.

Detailed Descrintion of the Embodiment: Referring first to Figure 1 of the accompanying drawings, there is illustrated therein an element protection control 1 which is a modified form of the control that is described in GB-A-2 194 099 with reference to Figures 3A, 3B and 3C thereof, or a modified form of the control that is described in GB A-2 248 724, or a modified form of the controls that are described in GB-A-2 283 155 and GB-A-2 283 156.

More specifically, the element protection control 1 is as described in the appended copy of British Patent Application No. 9522594.2 which forms an integral part hereof. Reference should be had to the aforementioned specifications and to the appended copy of British Patent Application No. 9522594.2 for a full understanding of all aspects and advantages of the element protection control 1 which will be described only briefly in the following. The disclosures of GB-A-2 194 099, GB-A-2 248 724, GB-A-2 283 155 and GB-A-2 283 156 are incorporated herein by reference and the disclosure of British Patent Application No. 9522594.2 is incorporated into this description by provision of the appended copy.

The element protection control 1 provides for the supply of electric current through the control to the heating element of an electrically powered water heating vessel or the like to which the control is affixed, subject to the condition of a bimetallic blade 2 of the control. The bimetallic blade 2 is held in close thermal contact with the heating element and in response to an element overtemperature condition is arranged to open a set of switching contacts within the control thereby to interrupt the supply of electric current through the control. The bimetallic blade 2 is snap-acting in its operation and acts upon a push-rod to open the switching contacts.

A secondary level of protection is afforded by mounting the bimetallic blade 2 on a carrier 3 which is formed of a. plastics material having a predetermined melting temperature, the carrier being under spring pressure in use of the control and being arranged so that in the event, however unlikely, of the bimetallic blade 2 failing to operate so that the heating element temperature continues to rise the carrier will begin to soften and will deform under its spring pressure so enabling a set of spring contacts to open within the control. Further details of the general construction and operation of the control 1 will become clear from consideration of the abovereferenced specifications.

The appliance power connector 4 shown in Figure 2 is an appliance connector inlet part of a plug-and-socket type cordless connection system substantially as described in WO 94/06185 with reference to Figures 7 to 11 thereof. More particularly, the appliance connector inlet part 4 is similar in its construction to the part 130 shown in Figure 8B of the drawings of WO 94/06185 and is adapted to be mated with a complementary plug or appliance connector part 23 (see Figure 3 of the accompanying drawings) which is substantially as shown in Figure 9 of WO 94/06185, the appliance connector and appliance connector inlet parts being configured to enable relative rotation between the two parts throughout a full .3600 of rotation.The appliance connector inlet part 4 comprises a generally cylindrical cup-shaped member 5 formed of moulded plastics material and having a central pillar (not shown) formed with a central opening. An earth or ground terminal is provided centrally of the opening, a neutral terminal is provided in the side wall of the opening and a live terminal is provided on the outside wall of the pillar. As shown in Figure 2 which shows the cup-shaped appliance connector inlet part 4 in inverted position, the earth, neutral and live terminals are connected to respective spade or tab terminals 6, 7 and 8.

The element protection control 1 of Figure 1 and the appliance connector inlet part 4 of Figure 2 are adapted and arranged to be directly electrically coupled to each other in the manner described in aforementioned British Patent Application No.

9522594.2. As described therein the element protection control 1 and the appliance connector inlet part 4 may be successfully mated with each other with the terminal parts 7 and 8 of the latter engaged in recesses of the former throughout a range of relative positions and relative orientations of the two parts.

This is advantageous in that it facilitates manufacture to larger tolerances. Furthermore, again as described in British Patent Application No. 9522594.2, the element protection control 1 may be coupled on top of the appliance connector inlet part 4, thereby enabling a liquid heating vessel to be designed with a smaller diameter than would otherwise be possible, or the two parts may be adapted to be interconnected in side-by-side relationship thus providing a lower overall height than the 'on top' configuration.

Referring to Figure 3 there is shown a cordless liquid heating appliance 10, such as a cordless kettle, embodying the present invention. The appliance 10 has a plastics walled vessel 11 and a substantially planar electrical heating element 12 provided as a bottom wall of the vessel 11. The heating element 12 is supported on an inwardly projecting ledge or seat 13 of the vessel 11 and is sealed thereto to be water-tight by means of a ring seal 14.

The heating element 12 is made of stainless steel to prevent corrosion occurring on the upper face 15 thereof. The lower face 16 of the heating element 12 has a layer of aluminium spun thereon to improve the distribution of heat across the element 12, and also to provide a mounting surface for the appliance controls. A resistance heating element (not shown) is clenched into the aluminium layer in a manner known per se. At a central region of the lower surface 16, two spaced-apart stud formations 17 are provided for fixing a pair of elongate mounting brackets 18 to the heating element 12. Only a single formation 17 and mounting bracket 18 can be seen in Figure 3 because the other formation 17 and bracket 18 are provided directly behind those shown in Figure 3 and are not visible in the side view of this Figure.

The element protection control 1 is secured by rivets for example to one end of each of the mounting brackets 18 so as to enable the bimetal 2 and the plastics material carrier 3 to be located in close thermal contact with the underside of the heating element 12, the rivets passing through the holes 30 provided in the control 1. Power is supplied to the element protection control 1 by way of the appliance connector inlet part 4 which is directly electrically coupled to the control 1 in the previously mentioned 'on top' configuration and, dependent upon the condition of the control, is transferred through the control and to electrical terminations of the heating element by means of electrical conductors.The appliance connector inlet part 4 is mounted to the other ends of the elongate mounting brackets 18, the brackets 18 being so shaped as to support and secure the inlet part 4 in operative relationship with the element protection control 1. However, it is also possible for the mounting brackets to be so shaped as to mount the element protection control 1 and the inlet part 4 in the previously mentioned side-by-side configuration.

The connector inlet part 4 is provided on opposite sides thereof with mounting lugs 19 (see Figure 2). The elongate mounting brackets 18 include through-holes 20 at the ends thereof which are adapted to align with the mounting lugs 19 of the inlet part 4 when the latter is positioned in the base of the appliance 10. Screws 21 pass through the holes 20 and into the mounting lugs 19 to fix the inlet part 4 to the mounting brackets 18.

A bottom cover 22 of the appliance 10 is also secured to the mounting brackets 18 by the screws 21 which pass through apertures in the cover 22 which are aligned with the mounting lugs 19. The bottom cover 22 engages the inwardly projecting ledge 13 of the vessel 11, and the arrangement is such that the effect of securing the bottom cover 22 to the mounting brackets 18 is to pull the heating element 12 down onto the ring seal 14. Accordingly, when the appliance 10 is thus assembled, the heating element 12 is effectively sealed with respect to the interior of the vessel 11.

The provision of mounting lugs 19 on the inlet part 4 is particularly advantageous because it obviates the need for the provision of a specially formed plastics moulding as is required in the aforementioned recently produced cordless electric kettle. In addition, the reduced number of components required for assembly of the appliance advantageously reduces the cost of the appliance.

The through-holes 20 in the mounting brackets 18 are oversized (elongate) so as to allow relative movement of the connector inlet part 4 and the bottom cover 22 with respect to the heating element 12. The bottom cover 22 is always accurately aligned with the connector inlet part 4 but may be positionally adjusted within the clearance in the through-holes 20 during assembly to accommodate tolerances in the heating element manufacture.

Figure 3 shows the cordless appliance 10 set upon its base 24 with the complementary base connector part 23 of the cordless connection system engaged with the appliance connector inlet part 4. The base connector part 23 is substantially as described in WO 94/06185.

Having thus described the present invention by reference to a specific embodiment, it is to be well appreciated that modifications and variations thereto are possible without departure from the spirit and scope of the present invention as set forth in the appended claims. For example, the present invention is not limited to the herein described kind of element protection control and is not limited to the herein described kind of cordless connection system. In fact, the present invention could be readily applied to a corded rather than a cordless appliance, i.e. an appliance in which power is supplied to the appliance connector inlet via a flexible power cord. In addition, whereas the above described embodiment uses two mounting brackets, these could readily be replaced by a single mounting bracket performing the same function.The invention furthermore is not limited to use with planar electric heating elements of the described kind, but could also be used with other kinds of planar electric heating elements such as those of the kind which comprise a substrate having a resistance heating track or layer formed thereupon.

One such element which has been proposed comprises a stainless steel substrate having an electrically insulating layer formed on one side thereof, a resistance heating track or layer formed on the electrically insulating layer and a further electrically insulating layer formed over the resistance heating track or layer. As disclosed in GB-A-2 283 156, openings can be provided in the last-mentioned electrically insulating layer to provide power supply terminations of the heating element, and the element protection control can be formed with spring terminals arranged to contact said power supply terminations when the control is operatively juxtaposed with the heating element.

There follows a copy of British Patent Application No. 9522594.2 as an integral and essential part of the foregoing description.

Claims

CLAIMS:

1. A combination of an element protection control, an appliance power connector and a mounting bracket for an electrically powered heating appliance, said element protection control and said appliance power connector each being coupled to said mounting bracket for mounting to a heating element of said appliance.

2. A combination as claimed in claim 1, wherein said mounting bracket includes means for permitting adjustment of the relative mounting position between the appliance power connector and the heating element.

3. A combination as claimed in claim 2, wherein said adjustment means comprises an elongate through-hole for co-operating with a fastener extending through said hole.

4. A combination as claimed in any preceding claim wherein the mounting bracket comprises an elongate member which is arranged at one end thereof to be coupled to the element protection control and at the other end thereof to be coupled to the appliance power connector.

5. A combination as claimed in any preceding claim, wherein the mounting bracket is arranged to mount said element protection control on top of said appliance power connector or in side-by-side relationship with said appliance power connector.

6. A combination as claimed in any preceding claim, wherein the appliance power connector comprises at least one mounting lug for receiving a fastener.

7. A combination as claimed in any preceding claim, wherein the element protection control and the appliance power connector comprise electrical connector parts adapted to be coupled together so as to enable effective interconnection therebetween within a range of relative positions thereof.

8. A combination as claimed in any preceding claim, wherein said element protection control comprises a bimetal mounted to a thermally collapsible carrier, the action of the bimetal is arranged to provide a primary control function, and the thermally-induced collapse of the carrier is arranged to provide a secondary or back-up control function.

9. A combination as claimed in any preceding claim wherein said appliance power connector comprises an inlet part of a cordless connection system adapted for engagement with a complementary connector part enabling engagement of the two connector parts substantially irrespective of the relative rotational orientation thereof in the plane transverse to the engagement direction of the parts.

10. A combination as claimed in claim 9 wherein said inlet part and said complementary connector part are generally coaxially arranged.

11. A combination substantially as described herein with reference to the accompanying drawings.

12. A combination as claimed in any preceding claim affixed to an electric heating element.

13. A combination as claimed in claim 12 wherein said electric heating element comprises a generally planar heating element having the element protection control, appliance power connector and mounting bracket affixed to one side thereof.

14. An electrically powered heating appliance comprising a liquid heating vessel and a combination as claimed in claim 13.

15. An electrically powered heating appliance as claimed in claim 14 wherein said planar heating element is sealingly secured in said liquid heating vessel by virtue of a bottom cover of said vessel being secured to said mounting bracket.