It is well known that limescale ("scale") deposits in liquid heating appliances can produce undesirable particulate contamination. In domestic appliances such as kettles, this is commonly combated by a spout filter that retains any scale particles so that they are not poured out with the heated liquid e.g. into a user's cup.

However, this is only a partial solution as the scale particles are not collected but simply drop back into the chamber where liquid is heated. It is up to a user to periodically clean out the appliance to remove the build-up of scale.

There remains a need for improvements in liquid heating appliances to deal with scale.

According to the present invention there is provided a liquid heating appliance comprising:

a liquid heating chamber with a spout for liquid to be poured out;

a particulate filter arranged in the liquid heating chamber for liquid to pass therethrough before being poured out of the spout; and

a particulate trap arranged below the particulate filter in the liquid heating chamber to catch particulate material retained by the particulate filter;

wherein the particulate trap comprises a partially closed compartment, defined by one or more walls extending downwardly from an upper end, and a cover that extends to partially close the compartment at its upper end, wherein at least one wall of the compartment is permeable to liquid.

It will be appreciated that such a particulate trap is in addition to the particulate filter typically provided at or near the spout for liquid to pass therethrough before being poured out of the spout. The partially closed compartment of the particulate trap allows for the entry of particulate material such as scale but tends to retain that material so that it is collected rather than being free to move back into the liquid heating chamber. As at least one wall is permeable to liquid, but impermeable to particulate material, liquid is able to drain through the compartment while leaving the particulate material behind. The permeability of the wall(s) is chosen to ensure that at least macroscopic particles of scale (limescale i.e. calcium carbonate) are retained in the compartment.

It will be appreciated that, in use, when a user wishes to dispense liquid from the appliance they may tilt the appliance forwards to allow the liquid to escape via the spout. Particulate material e.g. scale, which forms within the liquid heating chamber, may be carried by the liquid towards the spout during dispensing but the particulate material may be held back by the particulate filter. Once a user stops pouring the liquid out and returns the appliance to its original position, i.e. tilts the appliance backwards, any remaining liquid in the region proximal to the spout may carry at least some of the particulate material retained by the particulate filter into the particulate trap. Alternatively, any particulate material retained by the particulate filter may simply fall into the particulate trap arranged therebelow. As the cover only partially closes the compartment at its upper end, the particulate trap may comprise an opening at the upper end of the compartment through which particulate material can enter the particulate trap. This opening may be positioned approximately level with a lower end of the particulate filter, so as to optimise capture of the particulate material held back by the filter.

In a set of embodiments, the liquid heating chamber comprises a maximum liquid fill level and the particulate trap is arranged, at least when the appliance is in a resting position, e.g. a vertical position, such that the upper end of the compartment is above the maximum liquid fill level. The particulate filter is also above the maximum liquid fill level, which means that any particulate material held back by the filter can drop into the trap arranged therebelow. In such embodiments the particulate trap is arranged to collect particulate matter that falls into the trap under the action of gravity, rather than material being carried into the trap by a downwards flow of liquid. As will be appreciated by those skilled in the art, arranging the particulate trap in this manner means that any floating particulate matter can only pass into the compartment of the particulate trap via its upper end when the appliance is tilted such that some of the liquid within the liquid heating chamber moves to a position above the maximum fill level, e.g. when pouring liquid out through the spout. The appliance is always upright, and the body of liquid in the heating chamber is always below the maximum liquid fill level, during heating. In this set of embodiments, particulate material within the liquid heating chamber is only collected and trapped during, and immediately after, liquid dispensing operations (i.e. not during heating).

In some embodiments, substantially all of the one or more walls may be permeable to liquid. For example, the compartment may be formed of mesh walls. This could ensure fast drainage but may not be necessary as only a relatively small volume of liquid may wash down through the trap. In some embodiments, at least one wall may comprise a permeable window. For example, the one or more walls may be solid with a permeable window, or multiple permeable windows, provided therein for drainage purposes. The particulate trap includes a cover that extends to partially close the compartment at its upper end. It will be understood that the cover does not fully close the compartment so that liquid and scale (or other particulate material) can flow down into the compartment e.g. through an opening as mentioned above. It is preferable that the cover is impermeable to liquid so that liquid tends to flow across the cover and carry scale into the compartment. The cover may extend substantially horizontally across the upper end of the compartment. However, this could result in some pooling on top of the cover and scale sitting on the cover rather than being washed down into the compartment for collection. In preferred embodiments the cover is angled downwardly into the compartment. The cover may be angled downwardly at any angle between 0 and 90° relative to the horizontal. Angles of 30 to 60° may be preferred to promote the flow of liquid into the compartment.

The cover may be substantially flat, especially if it is angled downwardly as described above. However the Applicant has realised that scale collection may be optimised by ensuring that liquid does not easily run off the sides of the cover and therefore miss the compartment. In some preferred embodiments the cover comprises at least one upstanding flange. For example, the cover may comprise a pair of upstanding side flanges. In embodiments wherein the cover is angled downwardly, the upstanding side flanges may be arranged either side of the downwardly angled surface, thereby preventing liquid from running off the side edges of the cover.

The degree to which the compartment is partially closed at its upper end may depend on how far the cover extends across the upper end. In various

embodiments, the cover extends across at least 50%, 60%, 70%, 80% or 90% of the cross-sectional area of the compartment at its upper end. In embodiments wherein the particulate trap comprising an opening as mentioned above, the opening may extend across less 50%, 40%, 30%, 20% or 10% of the cross- sectional area of the compartment at its upper end. This is beneficial in terms of keeping scale particles trapped inside the compartment, especially when the appliance is tilted forwards to pour liquid out of the spout. The cover can also prevent scale particles from escaping if the appliance is tilted backwards during use.

The particulate trap may be designed to provide a sufficient collection volume such that it does not need to emptied during the working life of the appliance. However, it is desirable for a user to be able to empty particulate material out of the compartment. The particulate trap may therefore be removable from the liquid heating chamber, for example mounted in the chamber in a removable manner. The Applicant has recognised that there are competing demands between the cover acting to trap material inside the compartment and a user being able to easily empty out the compartment. Thus in some embodiments the cover is moveable. For example, the cover may be hingedly connected to the trap. In some

embodiments the cover is removeable from the compartment or the compartment is removeable from the cover. Thus is it will be appreciated that the trap is preferably at least a two-piece construction comprising the compartment and cover as separate pieces. This means that a user can move or remove the cover from the compartment to access the contents of the trap more easily.

The particulate trap may be mounted in the liquid heating chamber independently of the particulate filter. Preferably the trap is mounted in a position close enough to the filter that material held back by the filter tends to fall or be washed down into the trap. In various embodiments the particulate trap is mounted such that the upper end of the compartment is arranged to coincide with a lower end of the particulate filter. As is discussed above, preferably the upper end of the compartment is arranged above a maximum liquid fill level within the liquid heating chamber.

Ideally the trap is positioned directly below the filter so that particulate material tends to be caught in the trap but the trap is not positioned high enough that the compartment physically interferes with liquid being poured out through the filter.

The trap may be mounted for the compartment to hang down from the lower end of the filter.

The Applicant has recognised that it can be convenient to exploit the particulate filter as a convenient means for mounting the particulate trap, thereby avoiding the need for additional mounting means elsewhere in the liquid heating chamber. Thus, in some preferred embodiments, the particulate trap is mounted to the particulate filter. For example, the particulate trap is connected to a lower end of the particulate filter. Any suitable mounting arrangement may be employed such as, for example, a snap fit or tongue and groove arrangement. The trap may be fixedly or moveably mounted to the filter. A moveable mounting arrangement may comprise an axle passing through the trap and the filter, e.g. providing a pivotal connection. In one or more embodiments, the particulate filter and the particulate trap have a multi-part construction.

As discussed above, it is convenient in at least some embodiments for the cover to be separable from the compartment so as to enable the trap to be opened when a user desires to empty it out. This may be achieved by the filter providing the cover and the compartment being moveably or removably mounted to the filter. The filter is typically mounted in a fixed position relative to the spout (although the filter itself may also be removable to facilitate cleaning). Furthermore, the Applicant has appreciated that when the filter provides the cover there is a predefined path for particulate material retained by the filter to fall onto the cover and then be washed down into the compartment. This can avoid the trap being mounted in such a way that there is an unintended gap between the filter and the cover. Preferably the particulate filter and cover are integrally formed as a single piece.

In some preferred embodiments the filter comprises a shelf extending into the liquid heating chamber to form the cover of the trap. The shelf may extend from a lower end of the filter. As is described above, the shelf may be angled downwardly into the compartment and/or comprise at least one upstanding flange. Such a shelf arrangement can ensure that there is no gap between the filter and the cover, so that substantially all particulate material retained by the filter falls down onto the shelf. In such embodiments, the compartment may be moveably or removably mounted to the shelf. This means that the compartment can be moved or removed relative to the cover for ease of access.

In at least some embodiments the particulate trap may be mounted in a fixed position in the liquid heating chamber. It may be desirable for the trap to stay in a fixed position when the appliance is tilted forwards to pour liquid out through the spout. In particular, it would be undesirable for the trap to move into a position that may interfere with liquid flowing to the spout. During normal use, a liquid heating appliance tends to either be sat stationary on a horizontal surface or picked up and tilted forwards (i.e. spout down) to pour liquid out through the spout. The Applicant has now recognised that a liquid heating appliance may be picked up and tilted backwards (i.e. spout up), which would not happen during normal use, so as to assist in collecting scale in the trap. Even if the trap is mounted in a fixed position, this act may help retained scale to fall down from the filter and into the trap.

However this action may be assisted by moveably mounting the trap in the liquid heating chamber such that the trap moves into a collection position when the appliance is tilted backwards. The collection position may, for example, be a position in which the upper end of the compartment is brought closer to the filter. When the appliance is tilted backwards, the effect of gravity is to pull scale particles away from the filter and the collection position of the trap is one that is arranged to better catch those falling particles.

In a preferred set of embodiments, in addition to any of the embodiments described above, the trap may be pivotally mounted in the liquid heating chamber. In general, it may be desirable for the trap to pivot so that it adopts different angular positions, relative to the filter, depending on the angle of tilt of the appliance. This may help the trap to swing into a position that does not interfere with liquid being poured out of the spout when the appliance is tilted forwards. In addition, or alternatively, this may help the trap to swing into a collection position to catch falling scale when the appliance is tilted backwards. The trap may be pivotally mounted so as to adopt a range of different angular positions relative to the filter. The angular position of the trap at a given angle of tilt for the appliance will of course depend on its centre of gravity and this can be adjusted when designing the compartment.

In addition, or alternatively, the compartment may be pivotally mounted relative to the cover. For example, the cover may be hinged. For example, the compartment may be pivotally connected to the shelf in some embodiments. This means that the walls of the compartment can pivot relative to the cover to change how partially closed or open the compartment is. This can be particularly useful for making the compartment more open when the trap moves into a collection position when the appliance is tilted backwards, e.g. to force any scale retained by the filter to fall backwards into the trap without the cover being in the way.

As is mentioned above, the centre of gravity of the trap, and in particular the centre of gravity of the compartment, will determine the angular position of the trap. When the trap is pivotally mounted in the liquid heating chamber, it would be expected that the trap would tend to pivot forwards, i.e. towards the spout, when the appliance is tilted forwards to pour. However, such movement of the trap could potentially interfere with liquid being poured freely out through the spout. It may be preferable for the trap to remain substantially stationary when the appliance is tilted forwards from its resting (i.e. vertical) position. This may be ensured by positioning the centre of gravity of the trap such that the trap does not tend to pivot forwards (i.e. towards a wall of the liquid heating chamber) when the appliance is tilted forwards to pour. The trap may hang down in the same position whether the appliance is vertical or tilted forwards. In addition, or alternatively, the trap may be pivotally mounted with the compartment resting against the filter and/or a wall of the liquid heating chamber when the appliance is in a vertical position. The wall of the liquid heating chamber may be straight or curved, e.g. depending on the shape of the appliance. The compartment may rest against the filter, for example the shelf of the filter providing a stop, regardless of the shape of the walls forming the liquid heating chamber. As the compartment is already resting against the filter and/or a wall of the liquid heating chamber, the trap is not able to pivot forwards even when the appliance is tilted forwards.

Although the trap may be arranged to remain substantially stationary when the appliance is tilted forwards, it may be preferable (as mentioned above) for the trap to pivot to a collection position that brings the upper end of the compartment closer to the filter when the appliance is tilted backwards from its resting (i.e. vertical) position. Thus in additional, or alternative, embodiments, the centre of gravity of the trap is positioned such that the trap tends to pivot backwards (i.e. away from a wall of the liquid heating chamber) when the appliance is tilted backwards from a vertical position. When the trap pivots backwards, the partially closed upper end of the compartment is brought closer to the filter in the collection position. In some preferred embodiments the centre of gravity is positioned such that the upper end of the compartment is brought closer to, or into physical contact with, the filter when the appliance is tilted backwards by an angle of up to 10°, 20°, 30° or 40° to the horizontal. It is not generally desirable to tilt the appliance back by more than 45° as this could cause liquid to overflow from the liquid heating chamber.

The collection position has been described as one in which the upper end of the compartment is brought closer to, or into physical contact with, the filter. This means that the trap is better positioned to catch any particulate material held back by the filter and forced to fall back down under gravity when the appliance is leaned back from its vertical resting position. However the fact that the upper end of the compartment is partially closed can interfere with the collection process. In those embodiments wherein the compartment is mounted to pivot relative to the cover, e.g. the cover being a fixed shelf provided by the filter, then the collection position is preferably one in which the cover is pivoted down towards the walls of the compartment. For example, the compartment may pivot backwards so as to bring at least one wall into contact with the cover in the collection position. This means that the cover does not extend to partially close the compartment at its upper end, or at least closes the compartment to a lesser degree. In the default position of the trap (when the appliance is vertical), the cover may extend across at least 50% of the cross-sectional area of the compartment at its upper end. In the collection position of the trap (when the appliance is tilted backwards), the cover may extend across less than 50% of the cross-sectional area of the compartment at its upper end. The compartment is therefore made more open and better able to catch scale falling down from the filter.

It has been mentioned above that it is desirable for liquid to be able to flow towards the spout to be poured out without being impeded by the presence of the particulate trap in the liquid heating chamber. The trap, and in particular the walls of the compartment, can be shaped to assist this. In a set of embodiments the

compartment comprises a downwardly extending, straight wall on a side closest to the spout and a downwardly extending, curved wall on a side furthest from the spout. The curved wall may allow liquid to flow more easily over the compartment to reach the spout. In a set of embodiments the compartment may comprise a substantially rectangular cross-section in the vertical direction, the cross-section defining a downwardly extending, straight wall generally opposed to a downwardly extending, curved wall. The curved wall may curve towards the straight wall as it extends downwardly. The rectangular cross-section may therefore be wider at the upper end of the compartment.

The design of the particulate filter, other than a shelf to optionally provide a cover for the compartment, is not particularly relevant to the present invention. The filter may be mounted in the liquid heating chamber so as to intercept liquid before it is poured out of the spout. Or, as is most conventional, the filter may be mounted in the spout. This is commonly known as a "spout filter". Any standard particulate filter construction, e.g. comprising a plastic or metal mesh, may be provided. The liquid heating chamber may be formed of plastics, metal and/or glass materials, as is well known in the art. The skilled person is free to choose the particular design of the liquid heating appliance. The liquid heating chamber may comprise an immersed electrical heating element or an electrically heated base, e.g. a so- called underfloor heater as found in many modern kettles.

The liquid heating appliance may be any appliance used to heat liquids, e.g. a tea maker, coffee maker or other beverage maker, a milk frother, or any liquid comestible heating appliance. However embodiments of the present invention may find particular use in water boiling appliances, which are most likely to suffer from scale problems. It is therefore preferable that the liquid heating appliance is a water boiler, such as a kettle.

Some preferred embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figs. 1A to 1C schematically show a first embodiment of a liquid heating appliance in cross-section in three different positions;

Figs. 2A to 2C schematically show a second embodiment of a liquid heating appliance in cross-section in three different positions;

Figs. 3A to 3D schematically show a third embodiment of a liquid heating appliance in cross-section in four different positions; and

Figs. 4A to 4D provide various views of the particulate trap seen in the

embodiments of Figs. 1 to 3. There is generally seen in Figs. 1A to 1 C a liquid heating appliance 2 comprising a liquid heating chamber 4 with a spout 6 for liquid to be poured out. The liquid heating chamber 4 also comprises a maximum liquid fill level 5 to which the liquid heating chamber should not be filled beyond. As can be seen, the maximum fill level 5 is below the spout 6 such that liquid cannot escape the liquid heating chamber as it is heated during normal use. This helps to avoid any potential harm to users which may otherwise occur from inadvertent escape of heated liquid from the liquid heating appliance 2.

A particulate filter 8 is arranged in the spout 6 for liquid to pass therethrough before being poured out. A particulate trap 10 is arranged below the particulate filter 8 in the liquid heating chamber 4 to catch particulate material retained by the particulate filter 8. The particulate trap 10 comprises a partially closed compartment 12, defined by one or more walls 14 extending downwardly from an upper end 16, and a cover 18 that extends to partially close the compartment 12 at its upper end 16. The cover 18 is a shelf extending from the filter 8 and angled downwardly to partially close the upper end 16 of the compartment 12. As is seen more clearly in Figs. 4A and 4D, at least one wall 14 of the compartment 12 is permeable to liquid.

The default resting position of the appliance 2 is seen in Fig. 1 A to be a vertical position, e.g. when the appliance 2 is resting on a countertop and not in use and when the appliance 2 is being used to heat liquid in the chamber 4. As can be seen in Fig. 1A, when in this default resting position, the particulate trap 10 is arranged such that the upper end 16 of the compartment 12 is above the maximum fill level 5. Accordingly, in this position, liquid cannot enter the trap 10 via an opening in the upper end 16. Instead, liquid can only enter the trap 10 via the upper end 16 when the appliance 2 is tilted forwards and liquid flows towards the spout 6, as seen in Figure 1 B. In this particular embodiment, a lower end 17 of the compartment 12 is below the maximum fill level 5 and thus may rest in the liquid in the default resting position.

When a user wishes to pour out heated liquid, the appliance 2 is tilted forwards as seen in Fig. 1 B. In both the resting and pouring positions seen in Figs. 1A and 1 B, the trap 10 hangs down from a lower end of the filter 8 with a front wall 14 of the compartment 12 resting against the filter 8. The trap 10 is pivotally mounted in the chamber 4, as will be described further below, but there is no pivotal movement of the trap 10 between these two positions. Fig. 1C shows an unusual position wherein the appliance 2 has been tilted backwards. This is an optional collection position in which the trap 10 has pivoted relative to the filter 8 such that the upper end 16 of the compartment 12 has moved against the filter 8. As the cover 18 is a shelf extending from the filter 8, which remains fixed in position in the spout 6, the pivotal movement of the compartment 12 has brought its front wall 14 up against the cover 18 so that the upper end 16 is fully open in this collection position. The scale trapping functions will be described in more detail below, with reference to Figs. 3A to 3D.

There is generally seen in Figs. 2A to 2C another liquid heating appliance 2' which differs in the shape of the liquid heating chamber 4' and spout 6'. Similarly to the first embodiment, the maximum fill level 5' is below the spout 6'. However, in this embodiment, the particulate trap 10 and maximum fill level 5' are arranged such that the lower end 17of the compartment 12 is above the maximum fill level 5' such that no part of the particulate trap 10 rests in any liquid whilst in the default position seen in Figure 2A. All the other features are the same as those seen in Figs. 1 A to 1C. As is described above, Fig. 2A shows the appliance 2' in a vertical position, Fig. 2B shows the appliance 2' in a forwards tilted position, and Fig. 2C shows the appliance 2' in a backwards tilted position.

Operation of the particulate trap 10 will now be explained with reference to Figs. 3A to 3D. The depicted liquid heating appliance 2" differs again in terms of the specific shape of the liquid heating chamber 4" and spout 6", but the particulate trap 10 is the same as described for Figs. 1 and 2. Similarly to the first embodiment, the appliance 2" comprises a maximum fill level 5" and the particulate trap 10 is arranged such that the lower end 17 of the compartment 12, at least in a default resting position (seen in Fig. 3C), extends below the maximum fill level 5". Also seen in Figs. 3A to 3D is an underfloor electrical heater 20 that is mounted to a base 22 of the liquid heating chamber 4" in order to heat the liquid therein.

Typically the appliance 2" is a cordless appliance for which electrical power is only able to be connected to the heater 20 when the appliance 2" is seated in an upright position on a power base unit (not shown). The appliance 2" must be lifted from its power base unit to be tilted forwards or backwards.

Fig. 3A shows the appliance 2" being tilted forwards to pour liquid out through the spout 6". The flow path for liquid e.g. water is shown by the light-coloured arrows. As liquid flows out through the spout 6", any scale particles 24 are held back by the filter 8 and may start to fall down onto the cover 18 under the action of gravity, as depicted by the dark-coloured arrows, due to the density of the particles 24. Some scale particles 24 may run down the angled cover 18 and fall into the compartment 12. It can be seen from Fig. 3A that the hanging position of the trap 10 does not impede the outflow of liquid. Fig. 3B illustrates how the appliance 2" may be tilted very far forwards, e.g. when it is almost empty, but the scale particles 24 trapped inside the compartment 12 are not able to fall out due to the angled cover 18. The cover 18 includes an upstanding side flange 26 that helps to guide scale particles 24 along the angled surface of the cover 18.

Fig. 3C shows the appliance 2" being stood upright in a vertical position after a user has finished pouring. It can be seen that the scale particles 24 held back by the filter 8 tend to fall down under the action of gravity onto the cover 18 and are washed down into the compartment 12. Liquid can run down through the compartment 12, as shown by the light-coloured arrows, because the compartment 12 has at least one wall that is permeable to liquid. Any liquid remaining in the chamber 4" therefore runs back down to settle at a level far below the maximum fill level 5". The trap 10 is self-draining with the scale particles 24 left behind. In order to ensure that all of the scale particles 24 drop down into the compartment 12, the appliance 2" can be tilted backwards as shown in Fig. 3D. ln the collection position illustrated by Fig. 3D, the cover 18 is pivoted down against the front wall 14 of the compartment 12 and the scale particles 24 are pulled by gravity down into the lower end of the compartment 12.

When it is desired to empty the scale particles 24 out of the compartment 12, the trap 10 is disassembled by demounting the compartment 12 from the filter 8. This will be understood with reference to Figs. 4A to 4D. Figs. 4A and 4B show how the filter 8 and trap 10 have a two-piece construction.

The compartment 12 is pivotally mounted to the filter 8 by axle points 28. The axle points 28 are formed on the shelf 18 that provides the cover for the compartment 12. The filter 8 comprises a plastics frame 9 integrally moulded with the shelf 18. A mesh 11 is fitted in or against the frame 9. The front and back side walls 14a of the compartment 12 are formed with permeable windows 15. The other side walls 14b of the compartment 12 are solid. The compartment 12 may also have a moulded plastics construction. The windows 15 may be integrally moulded mesh or separate mesh panels. As most clearly shown by Figs. 4B and 4C, the shelf 18 providing the cover for the compartment 12 has a pair of upstanding flanges 19 arranged either side of its top surface so as to help trap and guide scale particles down into the compartment 12. Figs. 4C and 4D show how the compartment 12 can be separated from the filter 8. The compartment 12 may be pivotally connected by a snap fit onto the axle points 28. The compartment 12 can therefore be demounted and removed from the appliance for cleaning and replacement, or a new compartment fitted. The filter 8 may be independently removable for cleaning or replacement as well.