GB2198631A

GB2198631A - A device for heating liquid

Info

Publication number: GB2198631A
Application number: GB08629926A
Authority: GB
Inventors: Francis John Adams
Original assignee: Kenwood Ltd
Current assignee: Kenwood Ltd
Priority date: 1986-12-15
Filing date: 1986-12-15
Publication date: 1988-06-22
Also published as: GB8629926D0

Abstract

A device for heating water to boiling point, wherein steam from the boiling water is utilized to cook food. The device comprises a vessel for retaining the liquid to be heated, a heater for heating the liquid to a predetermined temperature, and means for reducing the heater power, once the liquid has attained the predetermined temperature, to a level sufficient to maintain the temperature of the liquid. A timer is pre-set to cause a reduction in the power output after a time interval dependent on the volume of liquid in the vessel and additionally or alternatively a vapour-sensor to detect vapour from the liquid as it boils. The use of such a device in a kettle to maintain simmering of the water a predetermined period after the water has been boiled, is also disclosed. <IMAGE>

Description

A DEVICE FOR HEATING LIQUID This invention relates to a device for heating liquid and in particular, though not exclusively, to a device for heating water to boiling point, such as a kettle, or a food steamer wherein steam from the boiling water is utilised to cook food.

Known food steamers consist of a vessel accoarmodating a heating element for heating water contained in the vessel to boiling point, so as to produce steam to cook food supported in the vessel above the water level. However, steamers of this type may, once the water has been brought to the boil, continue heating the water at the same rate, thereby producing more steam than is necessary and consequently wasting energy.

Kettles of known type are now generally provided with a vapour sensor, which causes the power to be disconnected from the heating element once steam from boiling water in the kettle is detected. However, if the boiling water is not used immediately, the water goes off the boil and it may then be necessary to reactivate the heating element to bring the water back to the boil again before it can be used.

It is therefore an object of the present invention to provide a device for heating liquid, such as a food steamer or kettle, which alleviates the afore-mentioned problems.

According to the present invention, there is provided a device for heating liquid comprising a vessel for retaining the liquid to be heated, means for heating the liquid to a predetermined temperature, and means for reducing the power output of said heating means, once said liquid has attained said predetermined temperature, to a level sufficient to maintain the temperature of said liquid.

Preferably, the predetermined temperature is boiling point of the liquid and the power output of the heating means is reduced to a level to effect simmering of the water.

In one embodiment, the means for reducing the power output includes a timer pre-set to cause a reduction in the power output after a time interval dependent on the volume of liquid in the vessel.

Alternatively, the means for reducing the power output includes a vapour sensor located at a suitable position on the vessel to detect vapour from the liquid as it boils.

The invention will now be further described by way of example only with reference to the accompanying drawings, wherein Figure 1 shows schematically a sectional view of one embodiment of the invention, and Figure 2 shows schematically a side view of the embodiment shown in Figure 1.

Referring to the drawings, a food steamer comprises a vessel 1 containing an electric heating element 2 located adjacent its base 3 with an electrical lead 4, and arranged, when energised, to heat water 5 retained in the vessel 1. A removable support 6 having apertures, such as in a colander, sieve, etc, is disposed above the level of water in the vessel, and the vessel 1 is provided with a lid 7.

In operation, the heating element 2 is generally switched to full power output to boil the water in the vessel 1 to produce steam, which is then used to cook food placed on the support 6.

As shown in Figure 2, the vessel preferably includes a water level indicator including a sight tube 8 having graduations 9 in units of volume of water, such as litres. The sight tube 8 is preferably disposed at an angle to the vertical, so that there is a greater variation in the level as seen through the sight tube 8, as compared with the actual variation in water level in the vessel 1.

A timer unit 10 on the vessel 1 is set, preferably by a user of the steamer, to control the power output of the heating element 2, in dependence on the volume of water in the vessel 1. In this way, for example, the time period required for the known volume of water to reach boiling point at full power output can be set on the timer unit 1 and the heating element 2 is energised to full power of, for example, 400W for that period. At the end of the time period, when the water should be boiling, the timer unit 10 automatically causes a reduction in the power output of the heating element to, for example, 120W, to effect simmering of the boiling water. The steamer would therefore still produce sufficient steam during simmering to cook the food, without generating an excess of steam, which would waste energy.

Alternatively or additionally, the steam may include a vapour sensor 11, which detects the steam from the water once it has boiled and causes the power output of the heating element 2 to be reduced to effect simmering.

The streamer may also include a condenser (not shown) to condense the steam back to water, the condensed steam then being directed back into the vessel to be boiled again.

The power output of the heating element 2 could be controlled in any suitable manner. For example, burst-fire or phase control of the power to the element 2 could be employed, or alternatively a twin-powered element having two discrete outputs, respectively at maximum output and a reduced output for simmering.

The present invention could be employed in many alternative applications, particularly kettles, which may include the timer unit to maintain simmering of the water for, for example, a predetermined time period after the water has boiled.

Alternatively or additionally the kettle may include a vapour sensor to effect the reduction in the power output of the heating element after the water has boiled and thereby maintain simmering. In this way, it would not be necessary to re-energise the heating element subsequently to bring the water back to boiling point, if the boiling water is not immediately used.

A kettle of this type may also include a visual and/or audible warning to alert a user when the kettle has initially boiled and is then put on simmer.

Claims

1. A device for heating liquid comprising a vessel for retaining the liquid to be heated, means for heating the liquid to a predetermined temperature, and means for reducing the power output of said heating means, once said liquid has attained said predetermined temperature, to a level sufficient to maintain the temperature of said liquid.

2. A device according to Claim 1, wherein the predetermined temperature is the boiling point of the liquid and the power output of the heating means is reduced to a level to effect simmering of the water.

3. A device according to Claim 1 or Claim 2, wherein the means for reducing the power output includes a timer pre-set to cause a reduction in the power output after a time interval dependent on the volume of the liquid.

4. A device according to any one of the above claims, wherein the means for reducing the power output includes a vapour sensor located at a suitable position on the vessel to detect vapour from the liquid as it boils.

5. A device according to any one of the above claims, wherein the vessel includes a water level indicator including a sight tube having graduations in units of volume of water.

6. A device according to Claim 5, wherein the sight tube is disposed at an angle to the vertical.

7. A device according to any one of the above claims, wherein the device additionally includes a condenser to condense steam back to water and means to direct the condensed steam back into the vessel to be boiled again.

8. A device substantially as hereinbefore described with reference to Figure 1 and Figure 2 of the accompanying drawings.