GB2280596A - Electric kettle with unsupported or supported detachable filter sheet - Google Patents

Abstract

There is disclosed a water heating vessel with a filter unit for removing scum. The unit may comprise a self-supporting disposable filter paper. Alternatively, the filter unit may comprise a wire, nylon or paper filter sheet which is detachable from a supporting frame. The frame may be removable from the vessel or may be fixed. The filter may be supported between a pivoting frame (11) and vertical projections from the inner wall of the vessel (16). The filter unit may comprise a detachable filter sheet in the form of a sock over a filter frame. The detachable filter sheet aids cleaning or may be disposable. <IMAGE>

Description

Water Heating Vessels The present invention relates to portable electrical water heating vessels such as electric kettles and jugs.

It is well known that when hard water is heated in, for example, an electric kettle, scale forms on the heating element and also on the walls of the heating vessel itself. It has been found, however, that particularly when plastic vessels are used, the scale tends not to form on the walls of the vessel but instead remains in the water and tends to form a scum which floats on the surface. When the vessel is tipped in order to pour its contents this scum will very likely be poured from the vessel with the water.

Since the scum tends to float on the surface of the water one way to reduce this problem is to arrange for the water which is poured from the vessel to be taken from well beneath the surface. United Kingdom patent application GB 2261362A discloses an apparatus of the hot water jug or "jug-kettle" type which operates in this manner. A vertical barrier is placed inside the jug between the major part of the water heating space and the jug wall adjoining the spout. An aperture is provided towards the bottom of that barrier in order to provide a flow path from the water heating space to the spout. The barrier is substantially sealed to the walls of the vessel and is of substantially the same height as the vessel. Thus, when hot water is to be poured from the jug it must pass through the aperture in the barrier in order to reach the pouring spout. In this manner water is taken from the lower part of the jug and any scum which is floating on the surface of the water remains undisturbed.

This prior art document further discloses the use of a filter arranged between the jug interior and the spout to prevent scum from the surface of the liquid being poured from the jug. Such a filter also serves to prevent any particles which are in suspension from being poured from the jug. The principle of placing a filter device within a jug or kettle is also known from United Kingdom Patent GB 2251547B.

In both of these prior art arrangements a filter comprising a filter mesh surface and supporting frame is removably mounted within the liquid receptacle part of the jug or kettle so that when heated liquid is being poured out of the receptacle through the spout the liquid passes through the filter mesh.

A drawback with the devices disclosed in both of these prior art documents arises from the fact that after a period of time, it becomes necessary to clean the filter in order to remove the build up of scum, otherwise it becomes unsightly. Further, if this is not done the filter may become blocked, thereby reducing the flow of water from the heating vessel. This could in the extreme even prove dangerous because the user may attempt to tip the kettle further than normal in order to increase the flow of water. This may cause water to flow around the filter and out of the lid opening rather than through the filter which could potentially scald the user.

In both the prior art arrangements the filters illustrated are in the form of units comprising a frame which fixedly supports a fine filter mesh. In order to clean the filters the entire unit is removed from the jug or kettle. Satisfactory cleaning is however difficult to achieve in practice. The supporting frame stands proud of the mesh making it hard to clean the peripheral part of the mesh adjacent the frame. At the same time, care must be taken not to tear the fine filter mesh from the more robust frame.

According to the present invention there is provided an electric water heating vessel in the form of a kettle or jug and comprising a pouring spout communicating with the interior of the vessel via a filter assembly, the filter assembly comprising a frame member for supporting a removable filter sheet which is detachable from the frame member.

Thus, rather than having a removable filter unit comprising a mesh fixedly attached to a supporting frame, in the present invention the vessel is capable of receiving a removable filter sheet which is separable from the frame. The drawbacks of the prior art arrangements may therefore be avoided since, as discussed below, a separate filter sheet is at least easier to clean and may be disposable.

If the vessel were to be used in an area of soft water it may not be necessary to provide a filter sheet and in such circumstances the frame member will not interfere with the normal operation of the vessel.

However, the full potential of the invention is realised in hard water areas in which the vessel will further comprise a removable filter sheet secured in position by or in co-operation with the frame member. The filter sheet may be of any appropriate type such as wire mesh, a perforated metal sheet or nylon. In the case of nylon, a mesh having pores of around 50 micron diameter has been found to be suitable.

The filter sheet may be in generally planar form, or it may be formed into a particular shape for cooperation with a frame member. For example, the sheet may be in the form of an arc or a tube. A preferred form of filter is obtained if the one end of a tubular filter sheet is closed in order to form a sock which may be slid over a cylindrical or frusto-conical frame. It may then be held in position by resilient means such as an integral elasticated portion or a separate resilient band at its open end. In one such form, the "frame member" may simply comprise a lip around which the open end of the sock resiliently engages.

The filters discussed above are reusable since they are sufficiently robust to be washed. Washing these filters is however considerably simpler than those of the prior art since there is no frame to impair the cleaning process. It would, for example, be quite straightforward fully to clean such a mesh under a running tap using a scrubbing brush without missing regions adjacent a supporting frame. In the case of a perforated metal sheet, flexing the sheet may assist in dislodging scale from its surface and from within its perforations. This is not possible in the prior art systems.

In an alternative embodiment, however, a disposable filter sheet is provided The provision of such a filter is clearly advantageous since the task of cleaning a filter sheet is avoided completely. It is simply necessary for the user to remove a soiled filter from the vessel and replace it with a new one.

Disposable filter sheets could be made of wire or nylon mesh or a perforated metal sheet, as in the case of the reusable versions, however for reasons of economy it is preferred that paper filter sheets be used. Such filter sheets are known, for example, in coffee making machines.

It is believed that the provision of a disposable filter means in a kettle or hot water jug is in itself inventive. Thus, from another aspect the invention provides an electric kettle or jug having a replaceable, disposable filter means for cleaning water poured therefrom. Such filter means may be self-supporting, for example by forming them in a cone-shape. Selfsupporting filter means may be removably mounted for example to the inside of an aperture forming the pouring spout. It is, however preferred that a frame member be provided as discussed above for supporting a disposable filter sheet.

There are many possible configurations for the frame member within the kettle or jug. Clearly, it is important to make sure that the filter assembly is arranged in such a way that when the vessel is tipped in order to pour water therefrom, water from at least a major part of the vessel must pass through the filter.

One way to ensure this is to locate the filter frame near to the spout, for example arranged around an opening in the jug which leads to the spout. This form of construction is particularly convenient if a tubular or frusto-conical filter frame (as discussed above) is used. Thus, the jug would be constructed so that the spout communicates with the interior of the jug only via the interior of the frame. A filter sheet provided around the frame will therefore filter water poured from the jug.

An alternative arrangement, which is applicable to generally planar filter sheets, is to place the filter assembly in a generally horizontal configuration (defined with respect to the normal orientation of the kettle or jug) above the maximum water level. Such an assembly may however be difficult to engineer and fit within a kettle or jug in practice.

It has been found that a more satisfactory arrangement is achieved when the filter assembly is in a substantially vertical configuration in normal use.

This is particularly useful when the vessel is of the hot water jug variety. Thus, according to a preferred embodiment of the invention the filter assembly comprises a frame member in the form of an apertured internal wall arranged adjacent the spout and extending downwardly into the vessel and across a portion of the inside of the outer vessel wall at a spacing therefrom.

In the case of a jug having a generally cylindrical form it is therefore possible for the frame member to have straight vertical sides rather than having to follow a curved contour as is the case with the horizontal arrangement.

In order to provide sufficient rigidity to the frame member it is preferred to have a number of apertures in the internal wall separated by crossmembers. The apertures may be provided only towards the bottom of the vessel in order to avoid taking water from the surface where scum tends to collect. However, if a reasonably efficient filter sheet is employed this may not provide any significant advantages and the presently preferred frame member includes apertures in a substantial part of the area of the internal wall. This allows a large filter sheet to be used which will reduce the resistance to the flow of liquid and also not become blocked as quickly as a smaller filter sheet.

There are various ways in which the removable filter sheet may be attached to the frame member, for example by providing the frame member in two portions which clip together. However, it is preferred that cooperation between the filter member and the vessel wall serves to locate and retain the filter sheet therebetween. In one form, there are provided projecting members in the inside of the exterior wall of the vessel arranged to cooperate with the frame member in order to provide means for retaining the filter sheet. Preferably, a plurality of elongate vertical projections from the vessel wall are arranged to cooperate with parts of the frame member such that the filter sheet may be trapped therebetween. In use, a filter sheet may be placed either on the projections or on the frame member, the frame member then being brought into engagement with the projections. This assembly may be held together by frictional means, or preferably a positive register is provided or a clip in fit.

The frame member itself may be removable from the kettle in order to facilitate insertion or removal of the filter sheet. However it is particularly preferred that the frame member be pivotally mounted within the vessel. Thus, to replace a filter sheet a user simply has to pivot the frame member away from the vessel wall, replace the old filter sheet with a new one, or remove it for cleaning, and then reinsert it, and return the frame member to its original position. The provision of a pivot prevents any problems with correct alignment of the components and prevents the frame member from being misplaced. It is particularly preferred that a hinge be provided between the frame member and the vessel floor so that the frame member pivots about a horizontal axis.

In a typical jug-kettle this will enable the frame member to pivot back over the heating element and also provides a large opening into which the filter sheet may be placed.

For the most efficient operation it is desirable that no water can leave the vessel without passing through the filter assembly. Preferably therefore the frame member extends substantially all the way from the base of the vessel to the pouring spout. In order to avoid any liquid by-passing the filter assembly it is preferred to provide projections from the walls of the vessel to form a substantially sealing contact with the vertical sides of the frame member. In addition, a horizontally projecting member may be provided at the top of the frame member in order to prevent liquid from being poured over the filter assembly rather than through it.

The filter frame member could be produced from a suitably formed piece of metal such as stainless steel and it could be pivoted to the base of the vessel using a conventional hinge. However, in practice it is preferred to use a plastics material which may be moulded to the correct shape and to incorporate therein a foot portion which may be welded or adhered to the vessel floor. An integral "plastic hinge" may be provided between the foot and the main part of the frame member in order to allow pivotal motion. It is also preferred to provide the major portion of the frame member in substantially planar form.

Certain embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a partially cut away perspective view of a jug-kettle according to a first embodiment the invention showing a filter sheet in position; Figure 2 is a similar view of the jug-kettle of Figure 1 partially exploded to illustrate the manner in which a filter sheet is inserted; Figure 3 is a perspective view of a re-useable filter sheet for use in place of the filter sheet of Figures 1 and 2; Figure 4 is a partial vertical section of a jugkettle according to a second embodiment of the invention showing the spout and filter frame; Figure 5 is a perspective view of the filter frame of Figure 4; and Figure 6 is a similar view to Figure 5, showing a sock-like filter sheet in place over the filter frame.

The vessel illustrated in Figure 1 is of the well known water heating jug or "jug-kettle" type. The jug 1 has a handle 2, heating element 3 and pouring spout 4 arranged in the usual manner. Electrical connectors and control means are provided in order to provide and regulate the supply of current to the element 3 however these are entirely conventional and have been omitted from the drawings for purposes of clarity. The jug is also provided with a lid 5 (Figure 2) which is removable in order to allow the jug to be filled with water. The water receiving region of the jug 6 is in the main part defined by the base 7 and the cylindrical outer wall 8 except for a region beneath the handle 2 which contains the control apparatus.

A filter assembly 10 is provided along the wall of the jug in the region beneath the spout 4. The filter assembly comprises a frame member 11 which is generally flat and rectangular in shape. It has a number of filter sheet retaining bars 12 arranged across it in a horizontal direction thereby providing a series of openings 19. At the bottom of the frame member there is a foot portion 13 connected to the remaining portion of the frame member by a plastic hinge 14. The foot portion 13 is welded to the base of the jug and the hinge is positioned such that the frame member may be pivoted about a horizontal axis away from and towards the jug wall.

At the top of the frame member 11 is provided a lip 17 which projects into the jug in a plane substantially perpendicular to the jug walls. It also projects laterally beyond the sides of the filter assembly and the laterally projecting portions are curved in order to fit the contours of the interior of the jug. There is no obstruction between the pouring spout 4 and the region 18 provided behind the filter 10. The purpose of this lip 17 is to prevent water from being poured over the top of the filter assembly rather than through it in event that the jug is tipped too vigorously.

When the filter assembly is in the "closed" position illustrated in Figure 1, the vertical sides of the frame member 11 abut the curved side wall of the jug. Along this line of abutment on each side of the frame member are two elongate vertical ribs 15. The frame member 11 when closed provides a snug fit against these projections. Water is thereby prevented from passing in any substantial amount around the sides of the filter assembly. Thus, there is provided behind the filter unit a region 18 (Figure 2) which is in communication with the spout and which communicates with the main water receiving portion 6 of the jug by means only of the openings between the bars 12 of the frame member 11.

As shown in Figure 2, the frame member 11 has been pivoted about plastic hinge 14 in order to bring it into the "open" position. It will be noted that by providing the hinge 14 at the base of the frame member 11 the frame member is able to pivot back over the top of the heating element 3 and also that a very large opening is provided. In addition to the ribs 15 referred to previously, there are provided three further ribs 16 in the region of the wall beneath the spout 4. These ribs are arranged to cooperate with the frame member 11 in order to trap a disposable filter paper 20 in position between themselves and the frame member 11. Since the frame member is substantially flat, the tops of these ribs (ie. the surfaces furthermost from the wall) substantially define a plane. Thus, when the frame member is moved to the closed position by pivoting it as shown by the arrow in Figure 2, the horizontal bars 12 of the frame and the vertical ribs 16 provide a series of points which frictionally grip the filter paper 20 thereby firmly holding it in position.

In order to use the jug for the first time, it is necessary to place a disposable filter paper 20 into position inside the jug. This would commonly be fitted by the kettle manufacturer. This is done by removing the lid 5 of the jug, gripping the lip 17 of the filter frame member 11, and pulling it outwardly away from the spout 4. The frame member 11 will pivot about plastic hinge 14 thereby providing a gap between it and the ribs 16 which enables the filter paper 20 to be located in position. This may be done either by placing it across the ribs 16 or perhaps more simply by resting it on the frame member 11. The frame member may then be closed by pivoting it in the direction of the arrow of Figure 2 and pressing it firmly home between ribs 15.

Cooperation formations (not shown) may be provided at the top of ribs 15 which provide the frame member with a snap fit into its closed position.

Replacement of a filter paper entails exactly the same procedure as outlined above, except that it is, of course, necessary to lift out a used filter paper once the frame has been opened.

As an alternative to the disposable filter paper 20, a re-usable filter 30, shown in Figure 3, may be employed. The filter 30 is formed from a thin, flexible sheet of a non-corroding metal having perforations 31 etched therein. It is therefore of similar construction to the metallic filters used in certain coffee making machines. The re-usable filter 30 is held between the frame member 11 and ribs 16 in the same manner as the filter paper 20. However, when it becomes clogged, instead of being replaced, re-usable filter 30 is removed from the jug for cleaning. It may, for example, be scrubbed, and in addition, it may be bent back-andforth in order to dislodge particles from its surfaces or from within the perforations.

Turning now to Figures 4 to 6, a second type of vessel, which is also a jug-kettle, is illustrated. The jug 40 is of conventional design, except for the region around its spout 41. The spout is formed at the end of a broad channel 42 which communicates with the interior 43 of the jug only via a frusto-conical filter frame 44.

As may be seen more clearly in Figure 5, the filter frame has an upper part 45, around which is provided a flange 46. From this part depend four legs 47, at the distal ends of which is an annulus 48.

In use, a filter-bag 50 (Figure 6) is located over the filter frame 44. The filter bag is formed from nylon mesh having 50 micron diameter pores and is in the form of a sock dimensioned to fit closely over the filter frame. It has an elasticated upper part 51 which grips the upper part 45 of the filter frame 44 above the flange 46. The flange therefore prevents the filter bag from slipping off the filter frame.

When the jug is first used, lid 49 is removed in order to allow a filter bag to be fitted over the filter frame by stretching its upper part 51 sufficiently to pass over flange 46. The jug is then used in the normal way. When the filter becomes soiled, it may be removed (reverse process to fitting) and washed or renewed.

Claims (18)

Claims

1. An electric water heating vessel in the form of a kettle or jug and comprising a pouring spout communicating with the interior of the vessel via a filter assembly, the filter assembly comprising a frame member for supporting a removable filter sheet which is detachable from the frame member.

2. A vessel as claimed in claim 1, further comprising a removable filter sheet secured in position by or in co-operation with the frame member.

3. A vessel as claimed in claim 2, wherein the filter sheet is made of wire mesh, a perforated metal sheet or nylon.

4. A vessel as claimed in claim 2, wherein the filter sheet is a disposable filter paper.

5. A vessel as claimed in any preceding claim, wherein the filter frame is arranged around an opening in the jug which leads to the spout.

6. A vessel as claimed in any preceding claim, wherein the filter frame is generally cylindrical or frustoconical.

7. A vessel as claimed in claim 5 or 6, comprising a filter sheet in the form of a sock engaged with the filter frame.

8. A vessel as claimed in any of claims 1 to 4, wherein the frame member is in the form of an apertured internal wall arranged adjacent the spout and extending downwardly into the vessel and across a portion of the inside of the outer vessel wall at a spacing therefrom.

9. A vessel as claimed in claim 8, wherein the internal wall has a plurality of apertures separated by cross-members.

10. A vessel as claimed in claim 8 or 9, wherein cooperation between the filter member and the vessel wall serves to locate and retain a filter sheet therebetween.

11. A vessel as claimed in claim 8, 9 or 10, wherein projecting members in the inside of the exterior wall of the vessel are arranged to cooperate with the frame member in order to provide means for retaining the filter sheet.

12. A vessel as claimed in claim 11, wherein the projecting members comprise a plurality of elongate vertical projections to trap the filter sheet against the frame member.

13. A vessel as claimed in any of claims 8 to 12, wherein the frame member is pivotally mounted within the vessel.

14. A vessel as claimed in any of claims 8 to 13, wherein the frame member extends substantially all the way from the base of the vessel to the pouring spout.

15. A vessel as claimed in any of claims 8 to 14, wherein a horizontally projecting member is provided at the top of the frame member in order to prevent liquid from being poured over the filter assembly.

16. A vessel as claimed in any of claims 8 to 15, wherein the sides of the frame member co-operate with projections on the walls of the vessel substantially to seal the frame member to the walls.

17. An electric kettle or jug having a replaceable, disposable filter means for cleaning water poured therefrom.

18. A vessel substantially as hereinbefore described with reference to figures 1 and 2 or 4, 5 and 6.