Patent Description:
Kettles are well-known devices to rapidly boil water for, for example, making tea, cooking, or the like. A disadvantage of presently known kettles is that as water is heated by a heating element, a small quantity of water close to the heating element is heated to above its boiling point. The quantity of water changes phase to steam and collects as a steam bubble at a steam bubble initiation site, usually a surface imperfection. As the steam bubble has a lower density than water the steam bubble rises due to buoyancy. As the steam bubble rises, the temperature of the surrounding water is below boiling temperature, causing the steam bubble to also cool down below boiling temperature. As the steam bubble cavitates, significant sound waves are created. The noise caused by the cavitation is undesirable in a home environment. It is very difficult to spread the heat over a kettle surface of a tube heating element of the kind used in a variety of kettles. Therefore, water adjacent the tube heating element tends to heat up faster as opposed to water away from it creating an imbalance in temperature and magnifying the cavitation.

Attempts have been made to design a kettle to avoid the formation of steam bubbles by subjecting the interior surface of the kettle to a surface treatment such that minimal, or no, surface imperfections exist. This approach eliminates the initiation sites for steam bubbles, which reduces the amount of bubbles formed, the amount of bubbles that cavitate and therefore the noise level. However, the surface finish is vulnerable to damage such as scratching etc. Yet further, following successive boiling cycles, water will leave behind a residue, which will then act as steam bubble initiation sites. Document <CIT> discloses a noise-reducing and purifying electric kettle comprising a kettle body, a detachable kettle bottom mounted at the bottom of the kettle body, and a heating base. The kettle bottom is hermetically connected with the kettle body. A porous heat-conducting medium is arranged between the kettle bottom and the kettle body. The lower surface of the porous heat-conducting medium is in full contact with a heat-conducting surface of the kettle bottom, and the upper surface of the porous heat-conducting medium is communicated with an inner cavity of the kettle body.

It is an object of the present invention to address the above discussed problem, or at least provide a useful alternative to the above-mentioned kettles.

In a first aspect the present invention provides a kettle according to claim <NUM>.

Preferably, the horizontal area is in a plane below the bottom wall.

Preferably, the inner surface is generally planar and the plane is parallel to the inner surface.

Preferably, the plane is horizontal when the kettle is resting on a surface.

Preferably, the inner surface is horizontal when the kettle is resting on a surface.

Preferably, the housing is fixed to the hollow body by an adhesive located between the hollow body and the housing.

Preferably, the adhesive bonded to the sound-isolating layer.

Preferably, the heating element is retained by the sound-isolating layer such that a gap exists between the heating element and the bottom wall.

Preferably, the sound-isolating layer is formed from rubber silicone.

Preferably, the sound-absorbing layer is a foam.

Preferably, the kettle further comprises:.

Preferably, the controller is operatively connected to the heating element using a power cable to supply power to the heating element, and a communication cable to receive sensor data from the heating element.

Preferably, the base has a projection and the housing has a recess, the projection being locatable in the recess such that, when the projection is located in the recess, the magnetic power supply is aligned with receiving power module to supply power.

Preferably, the heating element occupies a horizontal area that is at least <NUM>% of the inner surface area.

More preferably, the heating element occupies a horizontal area that is at least <NUM>% of the area of the inner surface.

Even more preferably, the heating element occupies a horizontal area that is at least <NUM>% of the area of the inner surface.

Preferably, the heat density provided by the heating element is between <NUM> to <NUM> W/mm<NUM> in a <NUM><NUM> region.

Preferably, the elastic rubber mount has a shorter horizontal extent above the heating element than below the heating element.

Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings:.

As shown in <FIG>, a kettle <NUM> according to an embodiment of the present invention includes a base <NUM> and a hollow body <NUM>. The hollow body <NUM> has a bottom wall <NUM> and a side wall <NUM> extending upwardly from the bottom wall <NUM> to a rim <NUM>. The hollow body <NUM> also has a lid <NUM> to engage the rim <NUM>. As best seen in <FIG>, the hollow body <NUM> also includes a handle <NUM> attached to the side wall <NUM>, and a spout <NUM> also attached to the side wall <NUM>.

As shown in <FIG>, the bottom wall <NUM>, the side wall <NUM> and the lid <NUM> surround a cavity <NUM> to receive water to be heated. Further, the bottom wall <NUM> has a generally planar inner surface <NUM> facing the cavity <NUM>. The inner surface <NUM> has an area that is substantially horizontal when the kettle <NUM> is resting on a surface.

As further shown in <FIG>, the hollow body <NUM> also includes a housing <NUM> fixed to the hollow body <NUM>. The housing <NUM> is separated from the hollow body <NUM> by a sound-isolating layer or rubber mount <NUM>, preferably made of a silicone rubber.

The bottom wall <NUM> includes a heating element <NUM> that occupies a horizontal area as projected, for example, onto the inner surface <NUM> of the bottom wall <NUM>. For example, if the heating element <NUM> were a tube of <NUM> diameter and a horizontal length of <NUM>, it would occupy a horizontal area of <NUM><NUM>. In the preferred embodiment the heating element <NUM> is a resistive thin film transistor (TFT) element that forms substantially all of the bottom wall <NUM>. The heating element <NUM> occupies a horizontal area as defined by the width and length of a trace <NUM>, as shown in <FIG>.

The rubber mount <NUM> extends below the heating element <NUM>. The rubber mount <NUM> also wraps around an edge <NUM> of the heating element <NUM> such that the heating element <NUM> does not contact the housing <NUM>. Yet further, the rubber mount <NUM> extends a short distance above the heating element <NUM>, inwardly from the edge <NUM> such that the heating element <NUM> also does not contact the side wall <NUM>. That is, the rubber mount <NUM> has a shorter horizontal extent above the heating element <NUM> than below the heating element <NUM> to ensure efficient thermal communication between the heating element <NUM> and water contained in the cavity <NUM>. The rubber mount <NUM> also extends parallel to the side wall <NUM> between the side wall <NUM> and the housing <NUM>, such that the housing <NUM> does not contact the side wall <NUM>. The housing <NUM> and the rubber mount <NUM> are adhesively fixed to the hollow body <NUM>, for example at lower rounded corner <NUM> of the side wall <NUM>.

The housing <NUM> includes a first retainer <NUM> located below the rubber mount <NUM>. The retainer <NUM> is attached to the housing <NUM> by a set of fasteners <NUM>. A first sound-absorbing layer <NUM> is held between the rubber mount <NUM> and the retainer <NUM>. The first sound-absorbing layer <NUM> is preferably a foam. The first sound-absorbing layer <NUM> includes an aperture <NUM> to allow access to the heating element <NUM>. Located in the aperture <NUM> is a connector <NUM>, the connector <NUM> includes a power cable (not shown) connected to the heating element <NUM>.

The housing further includes a floor <NUM> located below the retainer <NUM>. The floor <NUM> is attached to the housing <NUM> by a set of fasteners <NUM>. A second sound-absorbing layer <NUM> is held between the retainer <NUM> and the floor <NUM>. The second sound-absorbing layer <NUM> is preferably a foam. The floor <NUM> includes a recess <NUM> above and around which is located a chamber <NUM>. The chamber <NUM> houses an electrical power receiving module <NUM>. The power receiving module <NUM> is adapted to receive a sensor signal from a sensor (not shown) via the connector and is also adapted to supply power to the heating element <NUM> via the power cable.

The base <NUM> is adapted to receive the hollow body <NUM> and includes an upper surface <NUM>. The upper surface <NUM> includes a location projection <NUM> adapted to be received in the recess <NUM>, the projection <NUM> is a rotating electrical connector. Located in the base <NUM> is a power supply module <NUM> adapted to supply power to the power receiving module 56using the rotating electrical connector. The base <NUM> further includes, in this embodiment, seven buttons <NUM>, though any number could be used, to receive instructions from a user and a controller (not shown). The buttons <NUM> are adapted to send a button signal to the controller. The first controller is adapted to operate the power supply module <NUM> in response to the button signal. The controller may also receive a sensor signal from the power receiving module <NUM>. In response to that indication the controller is also adapted to control the supply of power to the power receiving module <NUM>.

Finally, the base <NUM> includes a set of rubber feet <NUM> upon which the kettle <NUM> rests when placed on a surface (not shown).

Use of the kettle <NUM> will now be discussed.

The base <NUM> is connected to a power source (not shown), such as an outlet and the hollow body <NUM> is placed on the base <NUM>. When placing the hollow body <NUM> on the base <NUM>, the projection <NUM> is located in the recess <NUM>. The power supply module <NUM> is now able to supply power to the power receiving module <NUM>.

When the buttons <NUM> are operated by a user to indicate that water in the cavity <NUM> should be heated, the controller operates the power supply module <NUM> to supply power to the receiving power module <NUM>. The receiving power module <NUM> subsequently supplies power to the heating element <NUM>.

The heating element <NUM> is resistively heated and increases the temperature of the bottom wall <NUM> of the hollow body <NUM>. The heat transfer density of the heating element <NUM>, referring to the inner surface <NUM> of the bottom wall <NUM> is preferably between <NUM>-<NUM> W/mm<NUM> averaged in a, for example, <NUM><NUM> region. The bottom wall <NUM> transfers hHeat is transferred from the heating element <NUM> to water contained in the cavity <NUM>. As the water in the cavity <NUM> reaches its boiling point it starts to agitate.

The sensor, for example, provides the sensor signal to the controller indicating a water temperature. Once the water temperature reaches a pre-determined water temperature the controller ceases to supply power to the receiving power module <NUM>.

Advantages of the kettle <NUM> will now be discussed.

The horizontal area occupied by the heating element <NUM> is a substantial portion of the inner surface area <NUM>. Therefore, the heat transfer from the heating element <NUM> to the water contained in the cavity <NUM> occurs over a large surface area, compared with tube heating elements that were previously discussed operating on the same household wattage. By distributing the heat over a larger surface area the kettle <NUM> substantially reduces the likelihood that water will be heated above its boiling point, thereby reducing the likelihood that a steam bubble will form. As fewer, or no, steam bubbles are formed, no steam bubbles exist that can cavitate, which reduces, or eliminates, the noise created by steam bubble cavitation.

The hollow body <NUM> rests substantially on the sound-isolating rubber mount <NUM>. As the water agitates close to its boiling point, the sound-isolating rubber mount <NUM> absorbs a portion of and reduces transmission of the vibration to the housing <NUM> and the base <NUM>. This arrangement reduces noise created by vibrations caused by the agitation of the water.

The rubber mount <NUM> also retains the heating element <NUM>. The heating element <NUM> may vibrate when heated, due to the use of alternating current (AC). The retention of the heating element <NUM> by the rubber mount <NUM> absorbs a portion of and reduces the transmission of these vibrations to both the cavity <NUM>, as well as the housing <NUM>.

The sound-absorbing foam layers <NUM>, <NUM> absorb a portion of and reduce the vibrations and noise that may yet transfer through the rubber mount <NUM>.

Together, the heating element <NUM>, the sound-isolating rubber mount <NUM>, and the sound-absorbing foam layers <NUM>, <NUM> substantially reduce the noise produced by the kettle <NUM>.

For example, the cross section of the heater element <NUM> may only overlap the cross section of the lower surface <NUM> by more than <NUM>%, more than <NUM>%, or even more than <NUM>%.

Yet further, the heating element <NUM> could be a heating coil having a path and a width in the horizontal plane.

Yet further, the heating element <NUM> may be separate and extending in a parallel horizontal plane below, but adjacent and/or attached to the bottom wall <NUM>.

Claim 1:
A kettle comprising:
a hollow body (<NUM>) having a bottom wall (<NUM>) and a side wall (<NUM>) extending upwardly from the bottom wall (<NUM>) to a rim (<NUM>), with the side wall (<NUM>) surrounding a cavity (<NUM>) to receive water to be heated, the bottom wall (<NUM>) having an inner surface (<NUM>) facing the cavity (<NUM>), the inner surface (<NUM>) having an area;
an elastic rubber mount (<NUM>);
a housing (<NUM>) fixed to the hollow body (<NUM>); and
a heating element (<NUM>) in thermal communication with the bottom wall (<NUM>) to thereby heat the water, wherein the elastic rubber mount (<NUM>) wraps around an edge (<NUM>) of the heating element (<NUM>) such that the heating element (<NUM>) does not contact the housing (<NUM>);
wherein the elastic rubber mount (<NUM>) is located between the side wall (<NUM>) and the housing (<NUM>), and surrounds the bottom wall <NUM>); and
wherein the elastic rubber mount (<NUM>) comprises a sound-isolating layer, and the housing (<NUM>) further comprises a sound-absorbing layer (<NUM>) located below the sound-isolating layer;
wherein the hollow body (<NUM>) rests on the elastic rubber mount (<NUM>); and
wherein the heating element (<NUM>) occupies a horizontal area that is at least <NUM>% of the area of the inner surface (<NUM>).