Liquid heating appliance

Abstract

A liquid heating appliance 2 comprises a casing 4, defining a liquid heating volume, and a heating arrangement 18 for heating liquid contained in the liquid heating volume, where the casing further defines an aperture 17 for receiving the heating arrangement 18. A base cover 5 is mounted to the casing 4 so as to cover the heating arrangement. The base cover comprises a first bayonet mounting 10 element 7 and the casing comprises a second bayonet mounting element 9. The base cover is mounted to the casing by engagement of the first and second mounting elements. Preferably the first bayonet mounting element is integrally formed with the base cover and the second and the second bayonet mounting element is integrally formed with the casing. The heating arrangement may comprise an electrical heater 18b, a control unit 16 for the heater and a cordless electrical adapter, where the base cover comprises an aperture to align with the adapter when the base cover is mounted to the casing.

Description

The present invention relates to liquid heating appliances and methods for assembling said appliances. Conventional liquid heating appliances comprise a casing that defines a liquid heating volume for receiving a liquid to be heated. A heating arrangement is arranged within the appliance to heat the contents of the liquid heating volume. In many devices, the casing defines an aperture at its base that allows the heating arrangement to be inserted into the casing during assembly of the appliance. Such appliances typically comprise a base cover that is attached to the casing to cover the heating arrangement and to provide the base of the appliance. Typically, the base cover is held in place by three or more screws, which extend through the base cover and into mating bosses welded or bracketed to components of the heating arrangement. Alternatively, in some arrangements the three or more screws extend through the base cover and into an overheat control unit which in turn is fastened to the heating arrangement. It is generally necessary for the base cover to be fitted to the casing securely so that the appliance can be stable when resting on its base. However, the conventional process for mounting the base cover to the casing of the appliance is laborious, time consuming and expensive. Furthermore, particularly in smaller appliances, it can be challenging to design a layout for the base portion of the appliance that provides the space required for the bosses within which the fastening screws are received, owing to the limited space available. The present invention therefore seeks to provide a liquid heating appliance with an improved base cover assembly. When viewed from a first aspect, the present invention provides a liquid heating appliance comprising: a casing, defining a liquid heating volume; a heating arrangement for heating liquid contained in the liquid heating volume, wherein the casing further defines an aperture for receiving the heating arrangement; and a base cover mounted to the casing so as to cover the heating arrangement; wherein: the base cover comprises a first bayonet mounting element; and the casing comprises a second bayonet mounting element; and wherein the base cover is mounted to the casing by engagement of the first bayonet mounting element with the second bayonet mounting element. Thus it will be appreciated that the present invention provides an improvement whereby the base cover of the liquid heating appliance is mounted to the casing of the liquid heating appliance by a bayonet mounting mechanism that is part of the base cover and the casing themselves, meaning that the provision and handling of separate screws or other fasteners (e.g. clips), which can add to the cost and complexity of the assembly process, need not be required. This means that assembly of the liquid heating appliance can be achieved more quickly and at lesser expense in comparison to conventional appliances. Preferably the first and second bayonet mounting elements are integrally formed with the base cover and the casing, respectively. This can help to simplify the number of steps required in the assembly process. The base cover and / or the casing may be manufactured from a forming operation, for example a moulding operation where plastics materials are used. The casing and the base cover may be manufactured from any suitable or desired material. The casing and the base cover may be manufactured from different materials to each other, or may be the same material. The base cover and / or the casing may be made from one or more materials such as plastics, glass, metal (e.g. stainless steel), etc. The casing may be any suitable or desired shape. In some embodiments, the casing is substantially cylindrical. In some embodiments, the casing is frustoconical. In preferred embodiments, (at least part of) the heating arrangement defines a base of the liquid heating volume. In such embodiments, the heating arrangement is preferably arranged to close the aperture. However, in some embodiments, the base of the liquid heating volume is defined by a floor component that is separate from the heating arrangement. In such embodiments, the floor component is preferably arranged to close the aperture. Preferably the aperture is defined by an inner perimeter (e.g. circumference) of the casing. The aperture may be defined by the (e.g. circular) edge of the casing, for example the bottom edge of the casing. However, in preferred embodiments, the aperture is spaced from the (e.g. bottom) edge of the casing. In such embodiments, the casing may be divided by the aperture (and thus by the heating arrangement) into a liquid heating volume portion and a skirt portion, wherein the skirt portion is arranged below the liquid heating portion and the heating arrangement. The skirt portion may extend downwardly below the heating arrangement to form a compartment below the heating arrangement where a control unit or the like can be housed. Preferably the base cover is arranged to extend across (e.g. the entire cross-sectional area of) the skirt portion so as to cover the heating arrangement. The base cover preferably comprises a substantially planar base. The planar base preferably defines an underside of the base cover. This helps to ensure that the appliance is stable when placed on a planar surface, such as a worktop or a power base for the appliance. The base cover may be any suitable or desired shape. Preferably the base cover has a circular cross-section (e.g. in the plane of the planar base). The perimeter (e.g. circumference) of the base cover is preferably substantially equal to the perimeter (e.g. circumference) of the casing, at least at the point at which the base cover is mounted to the casing. In some embodiments, the base cover comprises one or more side walls. For example, the base cover may comprise a cylindrical side wall. The side wall(s) preferably extend upwardly from the perimeter (e.g. circumference) of the planar base. The provision of one or more side walls can improve the rigidity of the base cover, and can facilitate the mounting of the base cover to the casing as the base cover can be gripped more easily. In some preferred embodiments, the casing comprises a skirt portion extending downwardly below the heating arrangement and the one or more side walls of the base cover mate with the skirt portion. For example, the casing may comprise a cylindrical skirt portion. This can create a smooth outer wall for the appliance. The first and second bayonet mounting elements may respectively comprise a projecting part and a slot for receiving at least a portion of the projecting part (or vice versa). Preferably the slot is defined in the casing and the base cover comprises the projecting part. However, in some embodiments, the slot is defined in the base cover and the casing comprises the projecting part. Preferably the first bayonet mounting element engages with the second bayonet mounting element when the projecting part is received within the slot and the base cover is rotated relative to the casing. In some embodiments, the projecting part may extend horizontally from the base cover (i.e. in or parallel to the plane of the planar base of the base cover). Preferably, however, the projecting part extends perpendicularly from the base cover, e.g. perpendicularly to the planar base of the base cover. In some embodiments the projecting part extends from the edge of the one or more side walls. The projecting part may comprise a hook, comprising a vertical portion and a horizontal portion protruding perpendicularly from the vertical portion. Preferably the horizontal portion is arranged to engage with the corresponding slot. Preferably the vertical portion is perpendicular to the (e.g. planar base of the) base cover. Preferably the horizontal portion is parallel to the (e.g. planar base of the) base cover. The horizontal portion and the slot are preferably sized such that the horizontal portion provides a friction fitting with at least a portion of the slot. This can help to ensure that the base cover is statically mounted to the casing when the first and second bayonet mounting elements are in engagement. Preferably the slot comprises an axial portion and a circumferential portion, wherein the circumferential portion extends circumferentially from the axial portion substantially perpendicularly to the axial portion (i.e., so as to form an L-shaped slot). The axial portion preferably extends perpendicularly to the (e.g. planar base of the) base cover, and the circumferential portion is preferably in a plane parallel to the (e.g. planar base of the) base cover. The axial portion preferably extends from the edge of the casing proximal to the base cover. In preferred embodiments, the circumferential portion extends from the end of the axial portion of the slot. This can facilitate alignment of the projecting part with the circumferential portion, as the projecting part can be moved along the entire length of the axial portion until it is stopped by the end of the axial portion, at which point the base cover can simply be rotated relative to the casing to move the projecting part into the circumferential portion. This arrangement can particularly improve the ease with which the appliance can be assembled manually. The appliance may comprise only a single pair of bayonet mounting elements (said pair comprising the first bayonet mounting element and the second bayonet mounting element). However, preferably the appliance comprises a plurality of (i.e. at least two) pairs of bayonet mounting elements. Preferably the plurality of pairs of first and second bayonet mounting elements are spaced around the respective perimeters of the base cover and the casing. It will be appreciated that, owing to the engagement of the first and second bayonet mounting elements, the number of separate fasteners (e.g. screws) used to secure the base cover to the casing can be significantly reduced in comparison with conventional appliances. In some embodiments, no separate fasteners may be used at all, as the bayonet fastening elements may be sufficient to secure the base cover to the casing. Thus, in some embodiments the appliance does not comprise a separate fastener securing the base cover to the casing, for example by having no separate fastener securing the base cover to the control unit and / or heating arrangement. However, the provision of one or more separate fasteners can allow the base cover to be fixed to the casing more securely, which can help to improve the stability and safety of the appliance. In some embodiments, the base cover comprises a bore for receiving a separate fastener to secure the base cover (e.g. directly or indirectly) to the casing. The separate fastener may comprise a peg, rivet, raw plug, dowel, etc. Preferably, the separate fastener is a screw and the bore is a plain bore. Preferably the appliance (e.g. the heating arrangement, or control unit (where provided)) comprises a corresponding boss arranged to receive the separate fastener. Preferably the corresponding boss is arranged to align, preferably coaxially, with the bore when the base cover is mounted to the casing. The corresponding boss may be provided on the casing of the appliance. However, preferably the corresponding boss is provided on a component of the appliance that is separate to the casing. This means that, in the event that the casing becomes damaged, the base cover can still maintain a fixed relationship with the rest of the appliance. In some embodiments, the heating arrangement and / or control unit (where provided) defines the corresponding boss. In some embodiments, the heating arrangement comprises a heat diffuser plate that defines the corresponding boss. Thus, the base cover may be held in a static position by the bayonet mounting elements, before being fixed in position by inserting a separate fastener through the bore and into the corresponding boss. The separate fastener may provide a removable or permanent fixing. In some embodiments, the heating arrangement is an inductive heating arrangement. The heating arrangement may comprise a ferromagnetic heating plate that is heated when the liquid heating appliance is placed on an energised induction hob, thereby acting to heat liquid within the liquid heating volume. In some embodiments, the heating arrangement is an electrical heating arrangement. The heating arrangement may comprise an electrical heating element. The electrical heating element may be an immersed heating element, arranged within the liquid heating volume, or a heating element on a (e.g. under) surface of a heating plate that is arranged in contact with the liquid heating volume. In some embodiments, the electrical heating element comprises a thick film printed element on a (e.g. under) surface of a heating plate that is arranged in contact with the liquid heating volume. In some embodiments, the electrical heating element comprises a sheathed electrical heating element. The sheathed electrical heating element may be of a conventional ‘horseshoe’ construction with an electrical termination at either end. Regardless of the type of electrical heating element, the electrical heating arrangement may comprise a heat diffuser plate (e.g. made of aluminium) mounted to the underside of a base plate (e.g. made of stainless steel) that defines the base of the liquid heating volume. The electrical heating element is preferably arranged in conductive thermal communication with the heat diffuser plate. Preferably the electrical heating element is mounted to an underside of the heat diffuser plate. At least a portion of the heating arrangement is preferably sealed against the inner perimeter (e.g. circumference) of the casing. In some embodiments, the appliance comprises a control unit for controlling the supply of electrical power to the electrical heating arrangement. The control unit may be integrated into the electrical heating arrangement or provided separately in the appliance and connected to the electrical heating arrangement (by wired or wireless means). In preferred embodiments the electrical heating arrangement includes the control unit. In some embodiments, the control unit may comprise a switch for controlling the supply of electrical power to the heater. Preferably the control unit comprises one or more thermally sensitive actuators arranged to operate the switch at a predetermined temperature to interrupt the supply of electrical power to the heater. The predetermined temperature may correspond to a temperature within the appliance during an overheat (e.g. “dry-boil”) scenario. The predetermined temperature may correspond to a target temperature or state of the liquid within the liquid heating volume (e.g. boiling). In some embodiments, the liquid heating appliance is a cordless appliance. In some embodiments, the control unit may comprise a cordless electrical adapter part arranged to mate with a corresponding base electrical connector part of a corresponding power base stand to receive a supply of electrical power. The base electrical connector part may include tabs for electrical connection to a mains power supply cable, or the mains power supply cable may be integrated with the connector part. Preferably the liquid heating appliance is arranged to be seated on a power base stand and the base electrical connector part is mounted on the power base stand. The base cover may be arranged to abut the corresponding power base stand when the cordless electrical adapter part mates with the corresponding base electrical connector part, i.e. when the liquid heating appliance is seated on the power base stand. The cordless electrical adapter part and corresponding base electrical connector part may be of the type that can be mated regardless of their relative angular orientation, or at least through a wide angular range (e.g. at least 340° and preferably up to 360°). Suitable cordless connectors of this “360° type” are described in WO95 / 08024 and WO01 / 28294, and are available as the Strix P72 or P76 connector parts. In some embodiments, the base cover comprises an aperture arranged to align with the cordless electrical adapter part when the base cover is mounted to the casing. Preferably the corresponding base electrical connector part is arranged to extend through the aperture to mate with the cordless electrical adapter part when the liquid heating appliance is seated on the power base stand. In some embodiments, the control unit comprises an electronic control unit. The electronic control unit may comprise an electronic temperature sensor (e.g. a thermistor) arranged to detect a temperature within the liquid heating appliance, preferably the temperature of liquid contained in the liquid heating volume defined by the casing. The electronic control unit may comprise a switch (e.g. a relay, e.g. a triac) for controlling the supply of electrical power to the heating arrangement. The electronic control unit may be configured to operate the switch in dependence on a signal generated by the electronic temperature sensor. In some other embodiments, the liquid heating appliance comprises an electrical power socket for receiving an electrical power cord for connecting to a mains electrical power supply. In some embodiments, the liquid heating appliance comprises an integrated power cord. When viewed from a further aspect, the present invention provides a method of assembling a liquid heating appliance comprising: a casing, defining a liquid heating volume; a heating arrangement for heating liquid contained in the liquid heating volume, wherein the casing further defines an aperture for receiving the heating arrangement; and a base cover mounted to the casing so as to cover the heating arrangement; wherein: the base cover comprises a first bayonet mounting element; and the casing comprises a second bayonet mounting element; and wherein the base cover is mounted to the casing by engagement of the first bayonet mounting element with the second bayonet mounting element, the method comprising: positioning the base cover such that the first bayonet mounting element is aligned with the second bayonet mounting element; and moving the base cover relative to the casing so as to engage the second bayonet mounting element with the first bayonet mounting element. In some embodiments, moving the base cover comprises a first movement and a second movement. The first movement may comprise an axial movement of the base cover relative to the casing. The second movement may comprise a rotational movement of the base cover relative to the casing. Preferably the rotational movement is in the plane of the (e.g. planar base of the) base cover. Preferably the second movement follows the first movement (e.g. immediately thereafter). As mentioned above, the first and second bayonet mounting elements may respectively comprise a projecting part and a slot for receiving at least a portion of the projecting part (or vice versa). Preferably the first movement serves to move the projecting part of the first bayonet mounting element along an axial portion of the slot of the second bayonet mounting element. Preferably the second movement serves to move the projecting part of the first bayonet mounting element along a circumferential portion of the slot of the second bayonet mounting element. In some embodiments, the method further comprises securing the base cover to the casing using one or more separate fasteners, i.e. fasteners that are separate from at least the base cover and the casing. The method may comprise inserting a separate fastener (e.g. a screw) through a bore in the base cover to engage with a corresponding boss, so as to secure the base cover to the casing. Certain preferred embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1 shows a perspective view of a liquid heating appliance in accordance with an embodiment of the present invention; and Fig. 2 shows a perspective exploded view of the underside of the liquid heating appliance of Fig. 1. Figure 1 shows a perspective view of a liquid heating appliance 2, hereinafter the appliance 2, in accordance with an embodiment of the present invention. The appliance 2 comprises a casing 4, defining a liquid heating volume, a spout 6 and a handle 8. The top of the appliance 2 is closed with a lid 10. The appliance 2 further comprises a base cover 5 that is arranged to rest on a power base 12 having a 360-degree base electrical connector part 14 provided in the centre for supplying the appliance 2 with electricity. The base cover 5 has a dished shape including a planar base 5a and a cylindrical side wall 5b. Figure 2 shows a perspective exploded view of the underside of the liquid heating appliance of Figure 1. The appliance 2 comprises a heating arrangement 18, for heating a volume of liquid contained within the casing 4, and a control unit 16 connected to the heating arrangement 18 (electrical connections not shown). Both the control unit 16 and the heating arrangement 18 are mounted below the liquid heating volume. The cylindrical inner surface of the casing 4 defines a circular aperture 17 within which the heating arrangement 18 is arranged. The heating arrangement 18 extends across the aperture 17 so as to close the aperture 17. The heating arrangement 18 thereby forms the base of the liquid heating volume which is above. The control unit 16 comprises a cordless electrical adapter part 28 that is arranged to receive the base electrical connector part 14 of the power base 12. The control unit 16 controls the provision of electrical power from the power base 12 to the heating arrangement 18. The heating arrangement 18 transfers heat to the base of the liquid heating volume when electrical energy is provided to the heating arrangement 18, thereby heating the contents of the liquid heating volume. In this embodiment, the heating arrangement 18 comprises a sheathed electrical heating element 18a and a circular heat diffuser plate 18b mounted to the underside of a base plate 18c. The heating element 18a is of a conventional ‘horseshoe’ construction with an electrical termination at either end which can be used to electrically connect to the control unit 16. The heating element 18a extends substantially around the circumference of the underside of the diffuser plate 18b. The control unit 16 is mounted centrally on the underside of the diffuser plate 18b. The base cover 5 comprises six projecting parts, embodied in this example by hooks 7 (four of which are visible in Figure 2). The hooks 7 extend upwardly (i.e. away from the surface upon which the appliance 2 is arranged to be placed) from the perimeter of the base cover 5. Each hook 7 comprises an engagement portion 7a extending radially outwards perpendicularly from the uppermost end of the hook 7, thus giving each hook an ‘L’-shaped cross-section in the plane of the radius of the base cover 5. The casing 4 comprises a skirt portion 4a, defined below the aperture 17 (i.e. on the opposite side of the aperture 17 to the liquid heating volume). The skirt portion 4a extends circumferentially around the electrical heating arrangement 18 and the control unit 16. The inner surface of the skirt portion 4a defines six slots 9 (two of which are fully visible in Figure 2) for receiving the engagement portions 7a of respective hooks 7 of the base cover 5. Each of the slots 9 comprises an axial portion 9a, extending upwardly from the lowermost edge of the skirt portion 4a, and a circumferential portion 9b extending circumferentially from the uppermost end of the axial portion 9a, thus forming an ‘L’ shape that extends partially around the circumference of the skirt portion 4a. The circumferential spacing of the slots 9 is equal to the circumferential spacing of the hooks 7 of the base cover 5. In order to fasten the base cover 5 to the casing 4, each of the axial portions 9a of the slots 9 is first aligned with a respective hook 7 of the base cover 5. The base cover 5 is then moved axially relative to the casing 4 so that the engagement portions 7a of the hooks 7 are guided along the axial portions 9a. Once the engagement portions 7a reach the end of the axial portions 9a, the base cover 5 is then rotated clockwise relative to the casing 4 (when viewed from below) so that the engagement portions 7a are guided along the respective circumferential portions 9b of the slots 9. The height of each engagement portion 7a is substantially equal to the height of the circumferential portions 9b. Thus, after the engagement portions 7a have been moved into the respective circumferential portions 9b, vertical (i.e. axial) movement of the base cover 5 relative to the casing 4 is prevented, thereby fastening the base cover 5 to the casing 4. The base cover 5 further comprises a central aperture 11 that is arranged to align with the cordless electrical adapter part 28 of the control unit 16 when the base cover 5 is fastened to the casing 4. When the appliance 2 is placed on the power base 12, the base electrical connector part 14 extends through the central aperture 11 to electrically connect with the cordless electrical adapter part 28. The base cover 5 further comprises a bore 13 for optionally receiving a screw (not shown). The bore 13 is arranged to align with a threaded boss 15 defined in the control unit 16. The insertion of a screw through the bore 13 and into the threaded boss 15 allows the base cover 5 to be secured to the casing 4 (via the control unit 16 and the heat diffuser plate 18b) once the base cover 5 has been fastened to the casing 4 by the engagement of the hooks 7 with the slots 9.

Claims

1. A liquid heating appliance comprising:a casing, defining a liquid heating volume;a heating arrangement for heating liquid contained in the liquid heating volume, wherein the casing further defines an aperture for receiving the heating arrangement; anda base cover mounted to the casing so as to cover the heating arrangement; wherein:the base cover comprises a first bayonet mounting element; andthe casing comprises a second bayonet mounting element;and wherein the base cover is mounted to the casing by engagement of the first bayonet mounting element with the second bayonet mounting element.

2. The liquid heating appliance of claim 1, wherein the first bayonet mounting element is integrally formed with the base cover, and the second bayonet mounting element is integrally formed with the casing.

3. The liquid heating appliance of claim 1 or 2, wherein the base cover comprises one or more side walls.

4. The liquid heating appliance of claim 1 or 2, wherein the first bayonet mounting element comprises a projecting part, and the second bayonet mounting element comprises a slot for receiving at least a portion of the projecting part.

5. The liquid heating appliance of claim 4, wherein the projecting part extends perpendicularly from the base cover.

6. The liquid heating appliance of claim 4, wherein the projecting part comprises a hook, comprising a vertical portion and a horizontal portion, wherein the horizontal portion is arranged to protrude perpendicularly from the vertical portion.

7. The liquid heating appliance of claim 6, wherein the horizontal portion and the slot are sized such that the horizontal portion provides a friction fitting with at least a portion of the slot.

8. The liquid heating appliance of claim 4, wherein the slot comprises an axial portion and a circumferential potion, wherein the circumferential portion extends circumferentially from the axial portion substantially perpendicularly to the axial portion.

9. The liquid heating appliance of claim 8, wherein the circumferential portion extends from the end of the axial portion of the slot.

10. The liquid heating appliance of claim 1 or 2, wherein the appliance comprises a plurality of pairs of bayonet mounting elements.

11. The liquid heating appliance of claim 1 or 2, wherein the appliance does not comprise a separate fastener securing the base cover to the casing.

12. The liquid heating appliance of claim 1 or 2, wherein the base cover comprises a bore for receiving a separate fastener to secure the base cover to the casing, and the appliance comprises a corresponding boss arranged to receive the separate fastener.

13. The liquid heating appliance of claim 1 or 2, wherein:the heating arrangement comprises an electrical heater;the appliance further comprises a control unit for controlling the supply of electrical power to the electrical heater; andthe control unit comprises a cordless electrical adapter part arranged to mate with a corresponding base electrical connector part to receive a supply of electrical power.

14. The liquid heating appliance of claim 13, wherein the base cover comprises an aperture arranged to align with the cordless electrical adapter part when the base cover is mounted to the casing.

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