CN105326398B

CN105326398B - Liquid heating apparatus

Info

Publication number: CN105326398B
Application number: CN201510779750.8A
Authority: CN
Inventors: 文森特·J·加维; 科林·芒顿
Original assignee: Strix Ltd
Current assignee: Strix Ltd
Priority date: 2007-12-24
Filing date: 2008-12-23
Publication date: 2021-05-07
Anticipated expiration: 2028-12-23
Also published as: RU2010128467A; ZA201004678B; JP2011507649A; AU2008339615A1; KR20100117577A; CN105326398A; US20110058798A1; GB0725235D0; AU2010100783A4; CN101951819A; EP2240053A1; IL206547A0; WO2009081156A1; CA2710299A1

Abstract

A liquid heating apparatus having a first mode of operation which can heat a first volume of water and a second mode of operation which can heat and automatically dispense a second, lesser volume of water. The first mode may be provided by a removable liquid heating vessel (40). The second mode may be provided by a second heating chamber (58) comprising a heater (76) arranged to heat the liquid and dispense the liquid through the outlet (45). The second heating chamber (58) is filled with water from the removable liquid heating vessel (40).

Description

Liquid heating apparatus

Technical Field

The present invention relates to a liquid heating apparatus for heating/boiling a liquid such as water.

Background

There is a general need for heating water to prepare beverages almost worldwide. In the uk and elsewhere in europe, it is common for most households to have kettles for boiling water to prepare a spot beverage. In larger venues and elsewhere in the world, it is more common to keep a body of water hot or boiling for a prolonged period of time, perhaps all day long, to enable such beverages to be prepared "on demand", i.e. without having to wait for the water to heat up from room temperature. Examples of such situations are conventional electric kettles or so-called hot water bottles, which are more common in asia.

Both of these devices have their drawbacks. In the case of kettles, even with very high power kettles (three kilowatt scale), the time it takes for the user to heat the water from cold (i.e. the temperature at which it flows from the tap) is considered inconvenient. This is especially true if it is difficult to estimate the amount of water required when filling a kettle, and thus there is a tendency to boil more water than is required (which of course increases the time it takes to boil it). On the other hand, if the water is kept at or near boiling for a long period of time, a large amount of energy will be required to offset the inevitable heat loss.

Recently, apparatuses that attempt to solve such a drawback have been commercialized. These devices are said to be capable of producing a full cup of hot water from a cold water reservoir in a matter of seconds. However, these devices are generally based on tubular flow heaters (tubular flow heaters) and the applicant has recognized some significant disadvantages of such devices. First, as with typical tubular flow heaters, to avoid the danger of overheating the heater and/or excessive pressure build-up inside the tube due to hot spots created by vapor pockets (pockets), heating must be stopped before the water in the tube reaches boiling point. Another disadvantage is that although the heating rate of the heater is relatively fast, it is inevitable that there will be an initial amount of water passing through the heater that is not heated to the target temperature. This, in combination with water prepared later, which is still not itself at boiling point, lowers the average temperature of the water. The combination of these two factors means that the water actually provided by such a device is still well below boiling point by the time it is dispensed, making it unsuitable for example for making tea, and thus limiting its appeal to consumers.

The applicant has further realised that in addition to a one-cup hot water dispenser of the above type, most users still need to have a conventional kettle for use when a relatively large amount or real boiling water is required. This causes a problem of occupying kitchen space.

Disclosure of Invention

Viewed from a first aspect the present invention provides a liquid heating apparatus having a first mode of operation in which a first volume of water can be heated and a second mode of operation in which a second, lesser volume of water can be heated and automatically dispensed.

In accordance with the present invention, it will be apparent to those skilled in the art that a single device can be used to rapidly heat and dispense small amounts of water, or to heat or boil larger amounts of water in a more conventional manner. This has the advantage of allowing the user to select the appropriate mode of operation depending on the amount of water required at any particular time, without having to expend the expense associated with a single appliance to accomplish these tasks, or having to find space on the countertop for multiple appliances. Of course, it should be understood that the relative amount of water that can be heated in any mode is determined by the relative maximum volume; at least in a preferred embodiment, the first mode of operation may be used to heat a sufficiently small amount of water that would have been heated in the second mode instead. The amount of water that can be heated in the second mode may be fixed or may be variable, for example, by a user.

The device may provide separate reservoirs for the two separate modes of operation, but in a preferred embodiment, a common reservoir is provided. This may be arranged to dispense water (or another liquid) to the respective heating means depending on whether the first or second mode of operation is used, but in a preferred embodiment the apparatus is arranged to heat all of the water in the reservoir in the first mode of operation, or a smaller predetermined amount of water from the reservoir in the second mode of operation.

Since the reservoir can be removed from the rest of the device and brought to fill, for example, at a tap, the device preferably comprises a removable reservoir which advantageously facilitates filling. In a particularly convenient embodiment, the apparatus is further arranged such that water heated in the first mode of operation can be manually dispensed from the removable container. In a preferred case, the removable container may resemble a conventional kettle, so it will be appreciated that in these embodiments the appliance necessarily comprises a standard boiling kettle, but if the amount of water required is sufficiently small, the appliance is also configured to be able to heat and dispense water "on demand".

A common heating device may be used to heat the water in the first or second mode of operation. For example, the reservoir may include means to isolate small amounts of water heated in the second mode of operation therefrom. In other embodiments, separate heating means are provided for the first and second modes of operation, respectively. This may have some advantages in terms of optimising each heater for its particular use and also lends itself particularly to embodiments in which it is necessary to provide a complete kettle for operation in the first mode but which allows water in the kettle to enter the heater for the second mode of operation when it is placed on the appliance. It will be appreciated that in such an embodiment the kettle may be operated independently of the remainder of the appliance, and that when the second mode of operation is required, it is only necessary to place the kettle on the remainder of the appliance.

Such an arrangement is novel and advantageous in and of itself, and so when viewed from a further aspect the invention provides apparatus for heating liquid, the apparatus comprising a removable liquid heating vessel including a heater for heating liquid therein, the apparatus further comprising a second heating chamber arranged to heat the liquid and dispense the liquid through the outlet, wherein the second heating chamber is filled with liquid from the removable liquid heating vessel.

Preferably, one or both heaters are arranged to heat the water to boiling. In contrast to the first aspect of the invention, the removable liquid heating vessel provides a first mode of operation and the second heating chamber provides a second mode.

In accordance with all of the foregoing embodiments, it is preferred that the heater for heating liquid in a first mode of operation, for example the heater of the liquid heating vessel of the aspect of the invention described above, comprises a heater plate with a resistive heating element, for example a sheathed element, formed on or mounted to the underside of the plate. Preferably, the heater is arranged to close (close) an opening in the base of the container, as is well known in the art of kettles.

The provision of a separate heater for the second mode of operation, for example the heater of the second heating chamber of the aspect of the invention described above, may take any convenient form, for example a tube heater or some other form of flow heater, but it is preferred to provide a chamber which heats the liquid to the desired temperature and then dispenses it.

The automatic allocation of the second mode of operation may be achieved by any suitable means. For example, a pump may be employed or the apparatus may be set up so that the liquid is heated in its upper part and dispensed downward (lower down) by hydrostatic pressure. However, in a preferred embodiment, the water is arranged to boil in the second mode of operation and to be dispensed from the appliance by means of the vapour pressure generated during the boiling process.

In some embodiments of the invention, a common mechanism is provided to operate in either the first or second modes of operation, and to stop heating the liquid when the liquid reaches a predetermined temperature. This may take any convenient form, for example, electronic, and may depend on the temperature to which the liquid is heated. In a preferred embodiment of boiling water in both modes of operation, the common means preferably comprises a steam switch, for example comprising a snap-action bimetallic actuator, as is well known in the art.

In a further embodiment, separate means are provided to stop heating in the respective modes. For example, where a removable liquid heating vessel is provided, a conventional vapor switch may be provided. This allows, for example, the removable container to be as close as possible to a standard kettle, which is beneficial for user acceptance and to minimize rework.

The removable liquid heating vessel preferably includes valve means for selectively allowing liquid to enter the second heating chamber when the vessel is mounted on the appliance and to avoid leakage when the vessel is removed. The valve means may be provided in the container body, but preferably it is provided in a heater plate closing an opening in the base of the container. This is beneficial for locating the valve lowermost within the container and also means that a standard heater plate including the valve can be produced, thus allowing the appliance manufacturer to use the already manufactured appliance body.

Preferably, although not necessarily, the valve means is provided on the second heating chamber. Such valve means are preferably configured to close when a predetermined amount of water is present in the second heating chamber. This allows the second heating chamber to be automatically filled to the desired level. Which may for example comprise a float valve. According to one set of embodiments, a free floating valve member is used, which is more reliable than a flapper valve (robust). Advantageously, such a valve member is housed in a casing which allows the liquid to flow through but retains (retain) the valve member, the valve member having an upper position in which it abuts against the valve seat to close the valve, and a lower position in which it is retained in a lower part of the casing. The valve member may take any convenient form. For example, it may comprise a ball (ball). Alternatively, it may be in the form of a pill, a discus, or a stubby cylinder. In a preferred set of embodiments, the valve member tapers downwardly, e.g. is frustoconical. This has been found to minimise the potential for the valve member to jam in use.

Preferably, the second heating chamber valve means is configured such that increased pressure within the heating chamber tends to increase the closing pressure on the valve caused by the buoyancy of the valve member. Preferably, it comprises an elastic collar (collar) against which the valve member is pressed by the internal pressure inside the second heating chamber. This helps to avoid water or vapour leakage when the removable container is removed.

As is preferred, where separate heaters are provided for the two respective modes of operation, the apparatus preferably includes switching means which only allows one of the elements to be energised at a time. This is advantageous because it allows each heater to be at high power without risking overloading the grid power supply by energizing both elements simultaneously. In a simple exemplary embodiment, the switching device comprises a diverter switch, such as a rocker switch. Where such a switch means is provided, the steam switch preferably acts on the aforementioned switch means to switch off either heater being energised.

The above-described arrangement is considered novel and inventive in its own right, and therefore when viewed from a further aspect the present invention provides a switching arrangement for an electrical appliance, the switching arrangement comprising a switch having a first position in which power can be supplied to a first electrical circuit, a second position in which power can be supplied to a second electrical circuit, and a third position in which no power is supplied to any of the electrical circuits, the arrangement further comprising a thermally sensitive actuator arranged to act on the switch to move the switch from either of the first or second positions to the third position when the actuator reaches a predetermined temperature.

In further embodiments, electrical or electromechanical devices are employed to avoid simultaneous energization. For example, in one set of embodiments, a relay is used to connect power in series with one of the heaters and is arranged so that its contacts open when power is supplied to the other heater. Of course, those skilled in the art will readily appreciate that equivalent means may be employed to achieve the same functionality in an electronic manner. Preferably the means is such that when the heater of the second heating chamber is energised, the power supply to the removable liquid heating vessel is cut off. It is advantageous in that it allows the electrical apparatus in the liquid heating vessel to be fully standard. For example, a relay or other switching device may simply cut off power to a wireless connector such as the applicant's P72 connector for supplying power to the liquid heating vessel.

Drawings

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing the major components of an apparatus embodying the present invention;

FIG. 2 is a schematic circuit diagram showing an electrical switching arrangement for two heaters;

figures 3a to 3d are a series of schematic diagrams illustrating the use of an embodiment of the invention;

FIG. 4 is another schematic view of the second embodiment;

FIG. 5 is a perspective view of a third embodiment of the present invention;

FIG. 6 is a perspective view of another angle of the embodiment of FIG. 5 with the pitcher component removed;

FIG. 7 is a view similar to FIG. 6 with the outer cover removed;

FIG. 8 is a partially exploded view of the components above the heating chamber;

FIG. 9 is a cross-sectional view of the heating chamber;

FIG. 10 is a different cross-section of the heating chamber;

FIG. 11 is an enlarged cross-sectional view of the valve between the pitcher style water kettle and the heating chamber;

FIG. 12 is a perspective view of the lower part of the dispensing chamber;

FIG. 13 is a cross-sectional view of the dispensing chamber; and

fig. 14 is a schematic circuit diagram for an appliance.

Detailed Description

Figure 1 shows the basic components of an apparatus embodying the present invention. In this embodiment there is a quasi-standard kettle 2 having a handle 4 and a pouring spout 6. The kettle is equipped with a heater arranged to close an opening in its base and includes a sheathed heating element mounted to the underside of the metal plate. The kettle 2 also includes the applicant's standard U17 control unit to switch off the heater in the event of overheating of the heater due to dry or boil dry being switched on. As is well known in the art, such a control unit comprises the male part of a 360 degree radio connector. The female part of the connector 8 is visible on the base part 10 of the device.

The kettle 2 differs from a conventional kettle in that it comprises a self-closing valve (not visible) on its base which can be opened by the penetration of a tube 12 extending from the base 10 when the kettle 2 is placed on the base 10. At the lower end of the tube 12 is a further valve in the form of a float valve 13 which controls the flow of water from the kettle 2 into the heating chamber in the base 10.

The heating chamber inside the base 10 of the appliance has another heater 30 on its underside, said heater 30 being similar to the heater in the kettle 2. As with the inlet controlled by the float valve 13 just described, the base heating chamber is connected to a dispensing nozzle 14, which dispensing nozzle 14 extends from the base member 10 and terminates in a downward bend (loop) for dispensing heated water into a cup 16 or other container disposed therebelow.

Also communicating with the heating chamber and rising from the base 10 of the apparatus is a vertical vapour tube 18, the upper end of which has a narrow neck, beyond which is a heat sensitive snap acting bimetallic actuator 20. Although not shown in the schematic view of fig. 1, the bimetal 20 is positioned such that when the kettle 2 is positioned on the base unit 10 it is also located above the spout 6 of the kettle 2.

Fig. 2 is a schematic circuit diagram showing the switching device. It should be noted that the bimetal 20 acts on a toggle-type rocker switch 36. The rocker switch 36 has 3 positions. In the left and right positions it can form a loop between the common terminal 22 connected to the live side of the mains power supply (mains supply) and either of the other two

terminals

24, 26 connected respectively to the element 28 in the kettle 2 and the element 30 in the base heating chamber. No loop is formed at the center position of the switch 36.

This arrangement allows either or neither of the

elements

28 or 30 to be energized, but does not physically allow both elements to be energized at the same time. Thus, each element can reach the maximum rated power provided by the mains power supply-for example, 3kW in the uk. When the bimetallic actuator 20 reaches its operating temperature (e.g., 90 degrees celsius) after contact with the vapor, the bimetallic actuator 20 acts on the switch 36 to return it to a central, open position (as shown in fig. 2) that de-energizes both elements.

In series with the kettle element 28 is the respective live and neutral (neutral) pole set of switch contacts 32 of the U17 control unit. In series with the base heating chamber element 30 is a simple bimetallic thermostatic switch and thermal fuse switch or two bimetallic switches (not shown). These corresponding further switches ensure that the element is switched off in the event of overheating (for example, due to dry-boil-off or boil-dry-boil-off being switched on).

The operation of the device will now be described with additional reference to figures 3a to 3 d. Figure 3a shows the device with the jug 2 placed on the base element 10 and the cup 16 placed under the dispensing nozzle (not visible). In use, the user removes the kettle 2 from the base unit 10 and fills it with water from the tap in a conventional manner (fig. 3 b). It is then replaced on the base part 10, allowing the tube 12 to pass into the bottom of the kettle (penetrative) and thus allowing water to flow out of the kettle (i.e. if the base heating chamber is empty) with the float valve 13 open.

The user may boil a relatively large amount of water (e.g., up to two liters) in the first mode of operation. This is achieved by selecting the appropriate position for the rocker switch 36. This energizes the kettle element 28 so that it boils the entire content (content) in the kettle 2. When the water boils, the steam generated causes the bimetal 20 to operate to return the rocker switch 36 to a central off position, which cuts off the power supply to the cordless connector 8 and thus de-energises the element 28 in the kettle. Of course, instead of this device, a more conventional steam switch device may be used for the kettle 2 itself. It takes about 4 minutes to boil two liters of water through a 3kW heating element. Once the element is switched off after the water has boiled, the kettle 2 can be lifted and the water poured out in a conventional manner (fig. 3 c).

The second mode of operation may be used if the user instead only needs a cup of boiled water. This is achieved by selecting another position of the rocker switch 36 (fig. 3d) and thus energising the heater 30 in the base chamber. This mode rapidly heats the small amount of water in the heating chamber to boiling, so the resulting vapor enters the vapor tube 18 and actuates the bimetal 20 and resets the switch 36 to the central position thereby shutting off the element. The pressure increase accompanying the boiling of water in the chamber forces the water up through the dispensing nozzle 14 and into the cup 16. A full cup of water can be boiled and dispensed in about 30 seconds.

Fig. 4 schematically shows another embodiment. This has a removable jug 2 'with its own elements (not shown) and similar means for draining water from the jug 2' for rapid heating and automatically dispensing a predetermined small amount of water through the spout 14 'to the side inlet feed tube 12' of the cup 16. However, in this embodiment, instead of a heater on the bottom surface of the closed base heating chamber, there is a fluid heater 30' for heating the water in the second mode of operation.

Thus, it will be appreciated by those skilled in the art that the above described embodiments allow the user the flexibility of being able to boil a full cup of water or a full kettle of water in a conventional manner very quickly, without having to purchase two separate appliances and find storage space for the two separate appliances.

The described embodiment is only one example in which the invention may be implemented. Many variations and modifications are possible. For example, a single common element may be provided instead of two separate heating elements for the two modes of operation.

Fig. 5 shows a perspective view of another embodiment of the present invention. This generally comprises a removable liquid heating vessel provided in the form of a pitcher style kettle 40 on a support 42, the support 42 also serving to support a hot water dispensing chamber 44 with its dispensing nozzle 45 by means of a support post 46. The kettle 40 is shown with the lid and outer handle molding removed. This exposes a standard steam switch 48, such as the applicant's R48 steam control, which is used to shut off the kettle when the water therein boils.

Figure 6 shows the appliance with the kettle removed. This exposes a 360 degree radio connector 50, such as the applicant's P72 connector, which is located centrally in the region of the base 42 which receives the kettle. On one side of the radio connector 50 is a water valve housing 52, the purpose of which will be described later.

Also more readily visible in this figure is an on/off switch 54 located at the top of the hot water dispensing chamber 44 and a drip tray 56 located directly below the nozzle 45 (not shown in fig. 6).

Figure 7 shows a view of the main components of the appliance with the outer cover removed. Thus, the heating chamber 58 with which the valve 52 is in selective communication is now visible in the lower portion of the appliance. Extending from the side of the heating chamber 58 are two

tubes

60, 62 that connect the interior of the heating chamber 58 to the interior of the distribution chamber 44. The purpose of these two tubes will be described later.

Figure 8 shows a partially exploded view of the components above the heating chamber. The 360 degree wireless connector 50 is shown received in a unique recess 59 in the top surface of the heating chamber 58. The channel 61 is provided to accommodate electrical wires from the connector 50. The connector 50 is held in place by a plate 64, and the plate 64 is screwed, riveted, or otherwise attached to the top of the heating chamber 58. The retainer plate 64 also provides the valve housing 52. The valve housing 52 is mounted on an upstanding annular wall 66 at the top of the chamber and a novel resilient annular sealing member 68 is interposed therebetween as will be described in greater detail hereinafter.

The heating chamber 58 is formed by upper and lower parts which are clamped together by clamping

rings

70, 72, the clamping rings 70, 72 being screwed together by a series of bosses (boss) and screw means 74.

Fig. 9 shows a vertical section through the heating chamber 58. As can be seen from this figure, the sheathed resistance heating element 76 is bonded to an aluminium diffuser plate 78, which diffuser plate 78 is in turn bonded to the underside of a stainless steel heater plate 80, similar to that conventionally used in water boiling kettles. The heater plate 80 is attached to the upper body of the heating chamber 58 by a peripheral channel 82, said peripheral channel 82 being crimped over a downwardly depending wall portion of the heating chamber in accordance with the applicant's safety Seal system (Sure Seal system) described more particularly in WO 96/18331.

Also visible in this figure is a cross-section through one of the pipes 60 connecting the heating chamber 58 to the distribution chamber (not shown). This is an outlet pipe for conveying boiled water from the heating chamber 58 to the dispensing chamber. It will be apparent from the figures that inside the chamber the outlet tube 60 extends at right angles, terminating in a downwardly depending tube portion 84, the end of said tube portion 84 being located a few millimetres above the heater plate 80.

Fig. 10 also shows a vertical section through the heating chamber 58, but in this example the section is taken from a plane parallel to that of fig. 9. This shows another tube 62, which is a vent tube, connecting the heating chamber 58 to the dispensing chamber. The lower end of the snorkel 62 fits over a spigot (spibot) 86, which spigot 86 opens into an aperture in the interior top of the heating chamber 58.

Fig. 11 shows a vertical section through the kettle 40 at the top of the heating chamber 58. In this figure, the view is enlarged to more clearly show the valve arrangement, and some components are omitted to further increase clarity. The kettle 40 has a side wall 88. The bottom surface of the kettle is closed by a circular stainless steel heating plate 90, said heating plate 90 being provided on its bottom surface with an aluminium diffuser plate 92 and a coated resistance heating element (not visible).

An aperture is formed towards the edge of the heater plate 90 to receive a vertically projecting sleeve portion 94 of the kettle part of the valve mechanism. The sleeve portion 94 is sealed against the hole in the heater plate 90 by a gasket (grommet) 96. Below the sleeve portion 94, the kettle valve member comprises two concentric annular shrouds (shrouds): an inner housing 98 and an outer housing 100. The outer enclosure 100 is of a diameter such that it fits over the housing 52 of the oven valve assembly and has beveled edges (levelled edges) to aid in positioning.

Between the sleeve 94 and the inner housing 98 is a spring-loaded valve assembly comprising a vertically movable valve member 102 topped by a valve head 104, the valve head 104 being biased towards a respective valve seat 106 by a compression coil spring 108. The coil spring acts between the bottom surface of the valve seat 106 and the ring 110 at the bottom of the valve member 102. In the configuration shown in fig. 11, an upward force is applied to the lower ring 110 of the valve member, thereby lifting the valve head 104 away from the valve seat 106 to allow water to pass through the valve. Equally, however, it can be seen that when this force is removed, the coil spring 108 acts to close the valve, thus preventing further passage of water.

The components provided on the heating chamber side of the valve assembly include the outer shell 52 (previously mentioned with reference to figures 6, 7 and 8) which has a central, chamfered opening for receiving the inner shroud 98 of the kettle valve housing. Thus, when the two valve components are coupled, the housing 52 passes between the inner and

outer housings

98, 100 of the upper component. Inside the housing 52 is an annular sealing member 68 that provides a fluid tight seal against an upwardly projecting annular wall 66, the annular wall 66 being an integral part of the top of the heating chamber 58. The sealing member 68 has a central annular projection forming an upwardly open annular channel for receiving and sealing against the lower edge of the inner shroud 98 of the kettle valve component.

On the lower surface of the seal member 66 is an angled annular flange 112 that extends radially outward so that it has some degree of flexibility in the axial direction. Below the sealing member 66 is a generally frustoconical float valve member 114 which is movable vertically but whose downward movement is limited by a valve stop member 116. When the float valve member 114 is in the upper portion or in motion, its top surface presses against the angled annular flange 112.

Fig. 12 shows a perspective view from above of the dispensing chamber 44 with the upper cover removed. Figure 13 shows a vertical section of the components of the chamber with the upper cover in place. The main part 44a of the dispensing chamber is generally bowl-shaped, and the dispensing nozzle 45 is in a centrally located distinct recess 44 c. The trailing edge extending circular member is a raised, generally horizontal platform portion 44b into which outlet tube 60 and snorkel 62 emerge from the heating chamber. It should be noted that the two

tubes

60, 62 extend vertically a distance into the distribution chamber.

Mounted outside the distribution chamber (but as shown with reference to fig. 12) is an R48 vapor switch 118, with the on/off rocker switch 54 attached to the vapor switch 118. A vertical conduit (chimney)120 extends through but is isolated from the dispensing chamber 44 and opens directly below the bimetallic actuator (not clearly visible in fig. 12 and 13) of the vapor switch 118. This allows cold air to pass through the bimetallic actuator after its operation to allow it to reset relatively quickly.

As can be seen more clearly in fig. 13, the tube forming the outlet nozzle 45 extends vertically a distance into the distribution chamber 44 within a concentric downwardly opening tube 122 having a slightly larger diameter, which downwardly opening tube 122 is mounted to the upper cover of the distribution chamber. The downwardly opening tube 122 extends downwardly just short of the annular groove 44c located in the center of the main section 44a of the distribution chamber.

Fig. 14 is a schematic circuit diagram showing the main electrical connections between the various components of the appliance. As can be seen from the left side of the circuit diagram, the live, neutral and earth connections from the mains leads (not shown). The switch contacts of the vapor switch 118 provided in the distribution chamber are electrically connected in series between a line pole and the coil 124 of the relay (although not shown in this schematic, some form of commutation may also be provided). The relay contacts 126 are of the transfer type with a common contact 126a connected to the live pole. The normally open relay contact 126b is connected to the heating element 76 provided on the base of the heating chamber 58. Although not shown in the drawings, the electrical connection to this element 76 is made by a modified U-series controller having its own pair of overheat protection bimetallic actuators acting on the respective normally closed

contacts

128a, 128b on the live and neutral sides of the element respectively. Neon tube indicator 130 is connected across element 76 in series with a suitable resistor 132 to indicate when the element is energized.

The normally closed relay contact 126c is connected to the central hot terminal of the radio connector 50. The neutral and ground terminals are connected directly from the grid lead to the respective inputs.

The right side of the circuit diagram of fig. 14 shows a conventional electrical arrangement in a kettle. Thus, the heating element 134 is connected in series with the normally open contacts of the vapor switch 48 and also with the normally closed

contacts

136a, 136b acting through the superheating bimetal of the U17 controller. Similarly, a neon indicator 138 and corresponding resistor 140 are connected across element 134 to indicate when the element is energized.

Now, the operation of the embodiment described above with reference to fig. 5 to 14 will be described.

As with the previous embodiment, the appliance of this embodiment can be operated in two separate modes. In the first mode, the kettle 40 may be removed, filled with water and then replaced on the base. To start boiling, a switch-on (not shown) is pressed to close the contacts of the steam switch 48. In the normal state shown in fig. 14, power may be supplied through the wireless connector 50 to energize the element 134. Unless the user switches off the power supply again, heating continues until the water in the kettle boils, which causes the steam switch 48 to operate and disconnect power to the elements. The kettle 40 can then be lifted again and the boiled water can be poured out of its spout in the conventional manner.

However, if the user wishes to boil and dispense only a full cup of water, he or she may operate the appliance in a second mode of operation as described below.

When the appliance is first used, or the heating chamber 58 is otherwise emptied, it must be filled with water. This is achieved by filling the kettle 40 with water and placing it back on the seat 42. This allows water in the kettle 40 to drain into the heating chamber through the valve arrangement shown in figure 11. More particularly, the lower ring 110 of the valve member 102 in the valve part of the kettle is forced up against the force of the coil spring 108 by its contact with the inner annular projection of the sealing member 68 when the kettle 40 is replaced in the stand. This allows water to flow from the interior of the kettle 40, through the valve sleeve portion 94, through the valve member 102, and through the center of the sealing member 68 and over the edge of the float valve member 114 into the heating chamber 58. The vent tube 62 allows air to escape from the chamber even after the lower part 86 of the outlet tube has been covered.

As the water level in the heating chamber 58 rises, the float valve member 114 also gradually rises as the water rises until it seals against the annular flange 112 on the lower surface of the sealing member 68 with sufficient force to avoid more water entering the heating chamber 58. If the kettle 40 is now lifted again, the coil spring 108 will cause the valve head 104 to close against the valve seat 106 inside the valve housing of the kettle, thereby preventing water in the kettle from leaking. Similarly, the buoyancy of the compliant annular flange 112 of the float valve member 114 against the bottom of the seal member 68 will prevent water from being ejected from the lower components of the valve assembly. When the kettle 40 is replaced, no further water flows because the float valve member 114 remains pressed against the annular flange 112, although the kettle sides 104, 106 of the valve will be opened again.

To operate the appliance in the second mode, the user must open the switch 54 provided at the top of the dispensing chamber. It will be appreciated in view of the circuit diagram of fig. 14 that it energizes the relay coil 124 to open the

relay contacts

126a and 126c and connect the

contacts

126a and 126b in parallel. This has two consequences. The first result is that the kettle 40 cannot be operated since no power is supplied to the cordless connector 50, ensuring that the two

elements

76, 134 are not energised at the same time, which would consume excessive current for a normal domestic mains socket. Another result is that element 76 on the bottom surface of heating chamber 58 is energized and begins to heat the water in the heating chamber.

During the initial stages of heating, the build-up of pressure inside the heating chamber 58 is limited by a vent 62 connected to the dispensing chamber 44 at substantially atmospheric pressure. This avoids water that is not sufficiently heated from prematurely flowing out through the outlet tube 60. This also reduces any tendency of the float valve member 114 to "rock" against the seal member 68. This, together with the compliant annular flange 122, helps to prevent more cold water from entering the heating chamber during heating.

As the temperature of the water in the heating chamber 58 approaches boiling, pressure builds up and begins to force the water up the outlet tube 60 and thus into the dispensing chamber 44. As this action continues, nearly all of the boiling water within the heating chamber 58 is forced up the outlet tube 60 to fill the dispensing chamber 44. The water is continually forced up the outlet pipe until the water level in the chamber 58 drops below the lower end of the downwardly extending portion of the outlet pipe 88.

Turning to fig. 12 and 13, it can be seen that the boiling water initially enters the side chamber 44b and thereafter drains into the main part 44a of the chamber towards the central annular recess 44c and thus begins to fill the main part 44a of the chamber. As water continues to enter the dispensing chamber 44, the water level between the downwardly opening tube 122 and the upwardly extending outlet nozzle 45 rises until the water begins to flow over the top edge of the outlet tube 45 and thus down through the spout into the user's cup. This establishes a siphon (siphon) which causes virtually all of the water in the dispensing chamber 44 to be dispensed through the spout 45.

Once all of the water is forced upwardly from the heating chamber 58 through the outlet tube 60, steam from the heating chamber 58 is expelled from the top of the outlet tube 60 (and from the vent tube 62) and into the dispensing chamber 44. This causes the vapor switch 118 to be turned off, thereby interrupting the power to the relay coil 124 and thus causing the heating chamber element 76 to be opened.

When the pressure in the heating chamber drops, the float valve member 114 lowers downwardly against its stop 16, which automatically refills the heating chamber 58 with water from the kettle 40, provided that the kettle 40 is there and has a sufficient amount of water therein. If the kettle 40 is not there, the heating chamber 58 will be refilled the next time the kettle 40 is replaced. Thus, the kettle 40 acts as a convenient removable reservoir for the heating chamber. This allows the user to repeatedly prepare several cups of boiling water all day without refilling the kettle each time, without having to re-boil the same water multiple times (which is generally considered to be a deterioration in taste due to the removal of dissolved oxygen), and importantly, without wasting energy by boiling more water than is required.

If the heating chamber 58 is operated without any water therein, for example if there is no water in the kettle 40 to refill the chamber after the last use, one or the other of the bimetals in the modified U-series control of the protective element 76 will operate to open the

respective contacts

128a, 128 b.

Thus, it can be seen that the present invention provides a very versatile appliance which can be used both as a conventional kettle to heat relatively large volumes of water, or, if only a full cup of water is required, which can be heated and dispensed very quickly and efficiently in the second mode of operation. The kettle 40 then acts as a removable reservoir in this mode of operation, which is convenient in itself as it allows for easy refilling. Providing a relay to switch between the two elements avoids electrical overload.

Claims

1. Liquid heating apparatus for heating water in two modes of operation, the apparatus comprising a removable liquid heating vessel and a separate heating chamber, a first mode of operation comprising heating of water in the removable liquid heating vessel by a first heater, the removable liquid heating vessel being arranged such that the heated water can subsequently be dispensed from the removable liquid heating vessel, a second mode of operation comprising heating of water to boiling in the heating chamber by a second heater separate from the first heater, characterised in that the heating chamber has a smaller volume than the removable liquid heating vessel and comprises an outlet tube and valve means configured to close when there is a predetermined amount of water in the heating chamber, the heating chamber being arranged such that, in use, boiled water is ejected via the outlet tube into a dispensing chamber under the effect of the vapour pressure in the heating chamber created by the boiled water The heating chamber further comprising a vent for venting a portion of the steam generated by the boiling water into the dispensing chamber, the liquid heating apparatus further comprising a steam switch arranged to switch off the second heater when boiling water in the heating chamber has been dispensed.

2. The apparatus of claim 1, comprising a common reservoir for both modes of operation.

3. Apparatus according to claim 2, arranged to heat all water in the reservoir in the first mode of operation, or a lesser predetermined amount of water from the reservoir in the second mode of operation.

4. The apparatus of claim 1, 2 or 3, comprising a removable reservoir.

5. The apparatus of claim 4, configured such that water heated in the first mode of operation can be manually dispensed from the removable reservoir.

6. The apparatus of claim 1, 2 or 3, wherein one or both of the first and second heaters are arranged to heat water to boiling.

7. Apparatus according to claim 1, 2 or 3, wherein the first heater comprises a heater plate with a resistive heating element formed on or mounted to a bottom surface of the heater plate.

8. The apparatus of claim 1, 2 or 3, comprising separate means for stopping heating in the first and second modes of operation, respectively.

9. Apparatus according to claim 1, 2 or 3, comprising a switch arrangement which allows only one of the heaters to be energised at a time.

10. Apparatus according to claim 9, comprising a relay connecting a power supply in series to one of the heaters, the relay being arranged such that its contacts open when power is supplied to the other heater.

11. The apparatus of claim 9, wherein the arrangement is such that when the heater for the second mode of operation is energized, power to the heater for the first mode of operation is cut off.

12. The apparatus of claim 1, wherein the first heater of the removable liquid heating vessel is configured to close an opening in the base of the vessel.

13. Apparatus according to claim 1, 2, 3 or 12, wherein the removable liquid heating vessel comprises additional valve means for selectively allowing liquid into the heating chamber when the removable vessel is not removed and to avoid leakage when the vessel is removed.

14. The apparatus of claim 12, wherein the removable liquid heating vessel includes additional valve means for selectively allowing liquid to enter the heating chamber when the removable vessel is not removed and to avoid leakage when the vessel is removed, and wherein the additional valve means is provided in the heater closing the opening of the base of the vessel.

15. The apparatus of claim 1, wherein the valve arrangement comprises a float valve member.

16. The apparatus of claim 15, wherein the valve arrangement comprises an elastic collar against which the float valve member is pressed by internal pressure within the heating chamber.