GB2369768A

GB2369768A - Electric kettle

Info

Publication number: GB2369768A
Application number: GB0029744A
Authority: GB
Inventors: Robert Andrew O'neill
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 2000-12-06
Filing date: 2000-12-06
Publication date: 2002-06-12
Anticipated expiration: 2020-12-06
Also published as: GB2369768B; GB0029744D0

Abstract

Electric kettle has vessel 1, planar heating element 5, heating element over-temperature control device 4 located in a compartment under the heater 5, steam control device 9 located in an upper chamber 8 of vessel 1 and wiring duct 10 within vessel 1. Wiring duct 10 has a lower end sealingly engaged with an aperture in heating element 5 and an upper end engaged with upper chamber 8 and contains conductors for operatively connecting steam control 9 and element control device 4. Wiring duct 10 may be of metal and fixed to heating element 5. An ON/OFF switch may be included at the top of vessel 1, operatively connected to steam control device 9. Vessel 1 may be of moulded plastic within which heating element 5 is attached. Upper chamber 8 may be moulded within vessel 1 and cooperate with steam control device 9 to define wet and dry regions substantially isolated from each other within chamber 8. Electrical parts of steam control device 9 are contained in the dry region, and upper end of wiring duct 10 is sealingly engaged with the dry region.

Description

IMPROVEMENTS RELATING TO WATER BOILING VESSELS

Field of the Invention : This invention concerns improvements relating to water boiling vessels and more particularly, though not exclusively, concerns domestic water heating vessels such as electric kettles and hot water jugs.

Background of the Invention: Kettles and hot water jugs for domestic use have long been provided with an element protector (or dry boil) control which has the function of switching off the supply of electricity to the appliance heating element in the event of the heating element temperature rising above a predetermined safe level, for example on account of the appliance having been switched on empty. It has also been customary to provide such appliances with a steam sensor responsive to the generation of steam when water is boiled in the appliance to switch off or reduce the power output of the appliance heating element, thus ensuring an automatic operation.

The heating elements of such domestic kettles and hot water jugs have conventionally been of the type comprising a resistive heating wire encased within a metal sheath with mineral insulation provided between the wire and the sheath. Such sheathed heating elements (also known as immersion heating elements) have the disadvantage that, since they are immersed in the water that is being heated, they are subject to scaling which not only reduces

their efficiency but also makes them visually unattractive. For these and other reasons, there has been a move in recent years towards planar or underfloor heating elements which constitute the base of the vessel and can be easily cleaned. Such planar heating elements are commonly of two types, namely a first type which comprises a metal plate having a sheathed heating element as aforesaid clamped, clenched or otherwise secured or integrated into its construction, and a second type known as a thick film heating element which comprises a metal plate having a resistive heating element deposited on its undersurface by printing with electrically conductive ink, by use of lithographic techniques or otherwise.

It has become customary with domestic kettles and hot water jugs fitted with underfloor heating elements to provide the steam sensor, or boil control, and the element protector control in a compartment in the bottom of the appliance under the heating element. Our X4 series element protector control (described in GB-A-2 339 088) and Z5 steam control (described in GB-A-2 331 848) are adapted to be used in this manner, though not exclusively so, and the Strix U18 control system (described in GB-A-2 339 496) is exclusively adapted for this purpose. However, with this arrangement the control ON/OFF switch either has to be positioned at the bottom of the appliance or a mechanical linkage has to be arranged between an ON/OFF switch at the top of the appliance and the controls at the bottom. This limits the design freedom of appliance manufacturers and the provision of linkages in complex, costly to assemble and requires a housing of some sort to enclose

it and provide the necessary linkage pivot points. The housing, in turn, requires a cover to conceal the linkage and provide an attractive exterior appearance. Metal bodied appliances require an additional external moulding, or an extension of the handle moulding, to carry the linkage.

Objects and Summary of the Invention: It is the principal object of the present invention to overcome or at least substantially reduce the abovementioned problem.

According to the present invention a water boiling vessel provided with a planar heating element has an element protector control housed in a compartment under the heating element and has a steam sensor control housed in a chamber provided in the upper part of the appliance, there being a wiring duct within the vessel through which electrical conductors extend from the compartment under the heating element to the steam sensor control in the upper chamber and the wiring duct being sealingly engaged with an aperture in the heating element at the lower end thereof.

It has previously been proposed to provide a steam tube within an electrically heated water boiling vessel (see, for example, DE-A-4 403 638) with the lower end of the tube sealed to a planar heating element and the upper end of the tube arranged above the expected maximum fill level of the vessel. The purpose of such an arrangement is to convey steam generated when water boils in the vessel to a steam sensor control located in the bottom of the vessel, and not to provide a conduit for electrical connections between

upper and lower vessel compartments. It has also been proposed (see GB-A-2 212 664) to provide a steam control in an upper part of a vessel and to extend electrical conductors between the steam control and the bottom of the vessel via a hollow handle moulding of the vessel. This latter proposal, which has been widely used, does however place its own design constraints upon appliance manufacturers. As will be appreciated from consideration of the following detailed description of an exemplary embodiment, the provision of an interval wiring duct, fixed to an underfloor heating element and designed to communicate at its upper end with a chamber for housing the steam control, frees the vessel designer from constraints concerning the external appearance of the appliance.

The above and further features of the present invention are set forth in the appended claims and will best be understood from consideration of the following detailed description given with reference to the accompanying drawing.

Description of the Drawing: The single figure of the accompanying drawing is a schematic side view of an exemplary cordless water boiling vessel embodying the present invention.

Detailed Description of the Embodiment : The illustrated embodiment is a cordless hot water jug comprising a vessel part, or jug proper, 1 and a base unit 2 upon which the vessel part 1 is adapted to be seated in order that electricity supplied to the base unit may access the vessel part, a male connector part 3 being upstanding from the base part 2 and the vessel part 1 having a complementary female connector part 4 adapted to couple with the male connector part 3 when the vessel part 1 is set down on the base unit 2. In the embodiment shown the connector parts 3 and 4 are the CS4, CP7 3600 connectors that we manufacture and sell and which are substantially as described in GB-C-2 285 716. The invention is not restricted to cordless appliances and is applicable also to the corded type of appliance.

Referring to the drawing figure, the jug proper 1 shown therein is formed of moulded plastics material and has a thick film electric heating element 5 sealingly secured therein, for example by the method disclosed in GB-A-2 330 064. The heating element 5 constitutes the bottom of the water heating chamber 6 of the vessel and has a space thereunder which defines a compartment 7 in the bottom of the jug which accommodates the abovementioned CP7 female connector part 4, which is formed as an integral part of an X4 heating element protector control as described in GB-A-2 339 088.

The jug body is also formed with an upper chamber 8 which serves to house a Z5 steam control 9. The chamber 8 has a steam inlet hole (not

shown) enabling steam, generated when water is boiled in the jug, to access the steam control 9 and cause it to switch off or reduce the power output of the heating element 5, and also has other formations (not shown) which provide steam sealing for the Z5 control as is customary to isolate those parts of the Z5 control which are exposed to steam from the electrical switching parts of the control. An ON/OFF rocker knob (not shown) is provided at the top of the jug handle and interfaces with the Z5 steam control 9 in conventional fashion.

A wiring duct in the form of a stainless steel tube 10 extends at its lower end through a closely-fitting opening in the heating element 5 and is fixedly and sealingly mounted to the heating element in any convenient manner, for example by brazing. When the heating element 5 is assembled into the jug body, the upper end of the tube 10 is located in a hole provided in a lower wall portion 11 of the internal, upper chamber 8 of the jug and is sealingly engaged therein by use of a grommet seal 12 of suitable elastomeric material. Electrical conductors, appropriately insulated, connect the Z5 steam control to the X4 element protector control in the base compartment of the jug and, whilst these conductors are not shown in the figure for the sake of clarity, it is to be understood that they pass through the wiring duct 10. Additional electrical conductors can also be provided for powering indicator lamps etc. and these conductors can also pass through the duct 10.

Although not shown, it is to be well understood that the upper end of the wiring duct 10 accesses the chamber 8 at a part thereof which, by virtue of

internal formations provided in the chamber 8 which interface appropriately with the body of the Z5 steam control 9, is well isolated from the steam that is admitted to the chamber 8 and from steam condensate within the"wet"part of the chamber. The"wet"part of the chamber 8 is ventilated to permit escape of excess steam and may furthermore be provided with means enabling drainage of condensate, for example back into the interior of the vessel. Such drainage means might for example comprise a further tube connecting the "wet"part of the steam chamber to the vessel interior.

The jug body moulding has need for no passageways or ducts to carry the wiring between the steam control and the heating element protector control and its exterior surface can therefore advantageously be continuous, needing no cover to hide ducts which otherwise would give rise to lines and gaps such as to trouble the vessel designer. The only cover moulding that would be required in the described embodiment would be to provide access to and cover the handle and the Z5 steam control. The inclusion of integrally moulded internal ducts, as has occurred in the prior art, generally gives rise to external sink marks which disfigure and detract from the smooth external surface of the jug body moulding, again requiring to be disguised by otherwise superfluous design features. The present invention obviates the need for such integrally moulded internal ducts and enables the body moulding to be simplified considerably, which in turn has advantages as regards troublefree assembly and production.

Having described the invention in the foregoing by reference to a specific embodiment, it is to be well understood that the embodiment is exemplary only and that modifications and variations are possible without departure from the spirit and scope of the invention. For example, the invention, as aforementioned, can be used with corded appliances and can obtain the same advantages. Furthermore, controls other than our X4 and Z5 controls could be used to the same or similar effect. The invention could also be applied to metal bodied vessels, in which case the Z5 control might be carried in the upper part of a handle moulding and no additional external features would be required. The chamber for accommodating the Z5 steam control could, in such a metal bodied vessel, be fabricated on the upper shoulder of the vessel body, or the handle could have a moulded chamber where it is joined to the body, and the wiring tube could be accessed via the vessel wall to which it might be sealed by means of a suitable (e. g. angled) grommet moulding.

Claims

CLAIMS : 1. An electrically powered water boiling vessel having a planar heating element, a heating element overtemperature protection control located in a compartment under the heating element, a steam control located in an upper chamber of the vessel, and a wiring duct within the vessel having its lower end sealingly engaged with an aperture through the planar heating element and its upper end engaged with said chamber, the wiring duct containing electrical conductors operatively interconnecting the steam control and the heating element overtemperature protection control.
2. A vessel as claimed in claim 1 including an ON/OFF knob, at an upper location of the vessel, operatively interconnected with said steam control for enabling the condition thereof to be determined manually.
3. A vessel as claimed in claim 1 or 2 wherein the wiring duct comprises a metal pipe fixed to the heating element and extending upwardly from the upper surface thereof.
4. A vessel as claimed in any of the preceding claims comprising a moulded plastics vessel body within which the planar heating element is secured, the said upper chamber being moulded into said vessel body and having formations cooperating with a body portion of the steam control for defining wet and dry regions within said chamber which are substantially

isolated from each other, electrical parts of said steam control being in said dry region and the upper end of the wiring duct sealingly engaging with said dry region.
5. An electrically powered water boiling vessel substantially as herein described with reference to the accompanying drawing.