IMPROVEMENTS RELATING TO WATER BOILING VESSELS

Abstract: An electrically heated water boiling vessel has a double-walled construction with the walls both formed of stainless steel and, for conveying hot steam from within the vessel to a steam sensor control located in a compartment below its base, a steam tube extends between the vessel walls. The steam tube is not visible and does not detract from the vessel appearance, neither internal nor external, and leaves the vessel designer free of any design constraints associated with the need to provide for a steam tube.

Description: IMPROVEMENTS RELATING TO WATER BOILING VESSELS Field of the Invention: This invention concerns improvements relating to water boiling vessels, particularly though not exclusively electric kettles and hot water jugs and the like, which incorporate a steam sensor control responsive to the generation of steam when water is boiled in the vessel for switching-off or reducing the power supply to the vessel heating element. Background of the Invention: The provision of steam sensor controls in water boiling vessels is very well known and it has been commonplace to house the steam sensor control within the top of a handle of the vessel with a vent in the vessel wall directing steam generating inside the vessel to the location of the steam control. The provision of heating element overtemperature protection controls in water boiling vessels is also very well known for protecting the vessel against the possibility of being switched-on without first being filled with water. Separate steam sensor and heating element protector controls are well known, and also well known are combined controls wherein both steam sensor and element protection functions are provided in .one and the same integrated control. Additionally, separate controls adapted to be plugged one into the other are known, see in particular our XI element protector control and Jl steam sensor control which are adapted to be used separately and can also be plugged together, the XI control having a socket inlet into which terminal parts of the Jl control can be plugged, and more recently our X4 element protector control and Z5 steam control. The XI element protector control is substantially as described in GB-A-2 194 099 with reference to Figures 3 A, 3B and 3C thereof, the Jl steam control is substantially as described in GB-A-2 212 614, the X4 element protector control is substantially as described in GB-A-2 339 088 and the Z5 steam control is substantially as described in GB-A-2 331 848. Plastics bodied water boiling vessels have been very popular, but in more recent times metal bodied vessels have been making a come back, particularly at the more expensive end of the market. Stainless steel is the preferred material and there are a number of stainless steel kettles and hot water jugs currently available. These relatively-expensive stainless steel vessels incorporate steam sensor and element protection controls as aforesaid and commonly have their controls located in a compartment in the base of the vessel beneath a planar heating element which is commonly either of the kind comprising a sheathed heating element affixed to the underside of a metal heat diffuser plate or of the thick film kind comprising a metal substrate having a heating element track deposited on the underside thereof. These heating elements are preferred since they do not intrude into the vessel interior which, in consequence, has a clean and clutter- free appearance (to be contrasted with the arrangement of the conventional British kettle where a sheathed heating element is coiled into the bottom of the vessel interior). The problem arises with such stainless steel vessels as to how to convey steam from the interior of the vessel, above the water level, to the steam sensor control in the base compartment of the vessel. The solution to this problem has been to adopt the well known measure of providing a steam pipe within the vessel, the steam pipe having an upper end high in the vessel interior and extending downwards within the vessel and through the planar heating element to within the base compartment where its lower end provides for steam generated when water boils in the vessel to impinge upon the thermally-responsive actuator, a bimetal for example, of the steam sensor. However, this solution gives rise to the problem that the steam pipe is inevitably visible within the vessel and spoils the clean and uncluttered look of the vessel interior. Moreover, scale can form on the steam pipe within the vessel which makes it even more unsightly. 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, an electrically powered water boiling vessel has a double-walled construction and a steam tube for conveying hot steam from within the vessel to a steam sensor control located in a base compartment of the vessel is provided within or defined by the double-walled construction of the vessel. The main application of the invention is to metal bodied water boiling vessels, formed of stainless steel for example, in which case at least the outer wall of the vessel is formed of metal. The inner wall may also be formed of metal, but could be formed of a plastics material as described in our British Patent Application No. 0004563.3 filed 25 February 2000, in which case the plastics material inner wall can serve to reduce the amount of heat reaching the outer, metal wall of the vessel. The above and further features of the invention are set forth in the appended claims and will be well understood by consideration of the following description of an exemplary embodiment which is illustrated in the accompanying drawings. Description of the Drawings: The single Figure of the accompanying drawing is a cross-sectional view through an exemplary water boiling appliance embodying the present invention. Detailed Description of the Embodiment: Shown in the drawing is a double-walled water boiling vessel comprising an inner vessel part 1 which is formed of stainless steel and has attached to the bottom thereof a heating element 2 in the form of a sheathed heating element proper 3 affixed to a heat diffusion plate 4. An outer wall 5 also of stainless steel is affixed, by welding for example which can be done invisibly, to the upper rim of the vessel part 1 and extends downwards to below the level of the bottom of the vessel part 1 so as to define a compartment 6 under the vessel. The open bottom of the outer wall 5 is closed by a base 7 which can for example, be a plastics material moulding or can be of stainless steel. Within the compartment 6 there is provided an X4 element protection control 8 which not only serves to switch-off the power supply to the heating element 2 in the event of the temperature of the heating element exceeding a certain level, but also serves as a 360° appliance inlet connector, the illustrated vessel being of the cordless type which has to be set down onto a base part in order for the vessel to be powered through the base. Shown attached to the X4 control is a Z5 steam sensor control 9 which has a bimetallic, thermally-responsive actuator 10. A steam tube 11 is provided between the two walls of the vessel, the upper end of the tube 11 being above the full water level of the vessel 1 and ducting formations 12 being provided in the base 7 for directing steam emanating from the lower end of the steam tube 11 onto the actuator 10 of the steam control 9. A vent 13 provides for the lateral venting of exhaust stem so that, in accordance with the teachings of our British Patent Application No. 0019402.7, the exhaust stem does not condense upon the base unit of the cordless appliance and cause a userto think that the appliance is leaking. The steam tube 11 may be formed from stainless steel and welded in place prior to welding the outer wall 5 on the vessel part 1, or it may be a plastics moulding of any suitable section adapted to fit within the inner wall space and may include sealing features to seal its upper end to the inner vessel 1. This sealing is not required to be water tight, but should be reasonably so to ensure that leakage of steam and water around the steam tube is kept to a level which is not hazardous. The seal may take the form of an "L" shaped boot moulded from elastomer, into which the top end of the steam tube may be pushed. The fixing of the steam tube is also not shown, but may be by means of trapping the tube between the walls, or mounting it to the base 7 and supporting it between formations on the base and on the sealing moulding at the steam inlet. The advantages of the described arrangement are that there is no visible or intrusive steam tube within the water vessel, giving a very clean appearance, and there is no external steam tube which would have to be hidden within a handle moulding, for example, which is restrictive of the design of the handle and of its mounting. Similarly, the arrangement allows the steam control to be mounted below the vessel without giving rise to either of the foregoing design penalties, which leaves the handle free of the design constraints imposed by the need to accommodate the control and its electrical connections. The invention having been described in the foregoing by reference to a specific embodiment, it is to be appreciated that the described embodiment is exemplary only and that modifications and variations are available without departure from the spirit and scope of the invention as set forth in the appended claims. For example, the inner vessel part 1 could be formed of a plastics material, in which case the steam tube 11 could be integrally formed or could be constituted by integrally moulded formations on the vessel part 1 defining an open channel designed to be closed to constitute the steam tube by the fitting of the outer wall. The outer wall could itself be formed of a plastics material, possibly with a metallisation finish or appearance. It will be understood that in the foregoing description, no mention has been made of the provision of a spout on the vessel or of how a handle might be provided. These matters are considered to be within the routine skills of anybody skilled in the manufacture of water boiling vessels and need not be elaborated here.

Claims: CLAIMS: 1. An electrically heated water boiling vessel having a double-walled construction and wherein a steam tube extends between the vessel walls for conveying steam generated when water boils in the vessel to a steam sensor control of the vessel. 2. A vessel as claimed in claim 1 wherein the outer wall of the vessel is formed of metal, for example stainless steel. 3. A vessel as claimed in claim 2 wherein both walls of the vessel are formed of metal. 4. A vessel as claimed in any of the preceding claims wherein the steam sensor control is located in a bottom compartment of the vessel. 5. A vessel as claimed in any of the preceding claims configured as a cordless appliance adapted to be seated upon a base in order for power supplied to the base to be supplied through a power outlet connector on the base to a power inlet connector in the bottom of the vessel. 6. A vessel as claimed in claim 5 including means for venting exhaust steam outwardly and away from the surface of said base. 7. An electrically heated water boiling vessel substantially as herein described with reference to the accompanying drawing.

Inventors: GAETA ANTONIO MARTIN, O'NEILL ROBERT ANDREW, GAETA, ANTONIO, MARTIN, O'NEILL, ROBERT, ANDREW
Applicants: GAETA ANTONIO MARTIN, ONEILL ROBERT ANDREW, OTTER CONTROLS LTD, GAETA, ANTONIO, MARTIN, O'NEILL, ROBERT, ANDREW, OTTER CONTROLS LIMITED
Application year: 2001
Main classification: A47J27
IPC codes: A47J27