GB2185150A - An electric kettle comprising a temperature limiter - Google Patents

Abstract

The electric kettle comprises a vessel (1), a heating resistor (3) and a temperature limiter (4) for cutting off the electric supply to the resistor when the temperature of the water vapour in the vessel reaches the desired value. The temperature limiter (4) includes a bimetal strip (10) mounted in a chamber (5) communicating with the vessel interior. For water heating, the strip (10) latches a valve (13) in a position leaving a steam inlet (6) open to the chambers (5). As soon as the bimetal strip (10) reaches a desired temperature it releases the valve (13) which is then spring urged to automatically block the chamber steam inlet (6). The released valve pivots a tumbler (8) to cut off the electric supply to the resistor(3). A lever (20) can be pivoted to switch off the supply and disconnect the plug and socket (16-19), allowing the kettle to be removed from its stand (14). Use in electric kettles for preparing hot drinks such as tea, infusions and decoctions. <IMAGE>

Description

SPECIFICATION An electric kettle comprising a temperature limiter The invention relates to an electrickettleforprepar- ing hot drinks such as tea, decoctions, infusions and the like.

Known kettles comprise a vessel for holding water and comprising a heating resistor, and atemperature limiter adapted to cut off the electric supply to the resistor when the temperature of the water vapour in the vessel reaches the desired temperature.

In known kettles, the temperature limiter is disposed in a chamber communicating with the vessel interiorvia an aperture formed inthetop partofthe vessel wall. The temperature limiter is thus in contact with watervapourformed inside the vessel.

The applicants have found that these electric kettles have the following disadvantage: When the temperature limiter, which usuallycom- prises a heat-deformable bimetallic strip, has cut off the electric supply to the heating resistor, considerable time elapses before the temperature limiter can be reset, i.e. placed in the operating position so that the resistor can continue to be heated.

This disadvantage is due to the fact that the bimetallic strip in the temperature limiter remains in contact with water vapour from the vessel, so that it remains deformed until the temperature has fallen appreciably. It is thus impossible to reset the temperature limiter until the strip has returned to its initial non-deformed position.

The applicants have found that users often want to resetthetemperature limiter a short time afterthe electricity has been cut off, so that the water can still be maintained at the desired ideal temperature. The object ofthe invention is precisely to obtain the aforementioned aim.

The invention relates two an electric kettle compris- ing a vessel adapted to hold water and comprising a heating resistor, a temperature limiter adapted to cut off the electric supply to the resistor when thetem- perature of the water vapour in the vessel reaches the desired temperature, the temperature limiter being disposed in a chambercommunicatingwith the vessel interior via an opening formed in the top part of the vessel wall, the temperature limiter being re-settable bythe user and comprising a means which automatically blocks the chamber opening as soon as the temperature limiter is placed in the position for cutting off the electric supply to the heating resistance, the kettle also comprising a bimetallic strip undergoing deformation in dependence on the temperature to which it is subjected.

According to the invention, the kettle is char acterised in that the bimetallic strip is adapted when deformed to be moved between a position where the means is retained by the strip and releases the open ing, and a position where the strip releases the means and return devices move the means into a position where it blocks the chamber opening and simultaneously moves a switch into the position for cutting off the electric supply to the resistor.

Since the opening of the chamber containing the temperature limiter is blocked as soon as the electricity is cut off, the temperature in the cham ber fal Is very quickly and consequently the temperature limites very quickly reaches thetemperature at which it can be re-set. The usertherefore always has hot water at the desired ideal temperature.

Otherfeatures and advantages of the invention will be clear from the following description and accompanying drawings, given by way of example, in which: Figure lisa diagrammaticview in elevation, partly cut away and with partial longitudinal sections, of an electric kettle according to the invention, the temperature limiter being in the set position and the spring catch in the locking position for electrically connecting the base of the kettle; Figure2 is a diagrammatic view similarto Figure 1 except that the vessel and kettle base have been omitted, the diagram showing the temperature limiter in the position for cutting offthe electric supply; Figure 3 is a view in section along plane Ill-Ill in Figure1;; Figure 4 is a view in section along planelV-lVin Figure 1; FigureS is a top viewofthe switch and the rear part ofthetemperature-limiter rod; Figure 6 is a partial diagrammatic view of the spring catch and the base connecting box, when the electric connections are partly opened, and Figure 7 is a view corresponding to Figure 6, when the catch is completely pressed down and released from the base box.

In the embodiment shown in Figure 1, an electric kettle comprises a vessel 1 adapted to hold water and containing a heating resistor 3 near its bottom 2. A temperature limiter4 is disposed at the top of vessel 1 and adapted to cut off the electric supply to resistor 3 when the temperature of the watervapour in vessel 1 reaches the desired temperature.

The temperature limiter4 is disposed in a chamber 5 communicating with the interior of vessel 1 via an opening6formedatthetopofthesidewall7of vessel 1. The temperature limiter4 can be manually re-setbythe user, using atumblerswitch 8.

The temperature limiter4co-operateswith a means 9 comprising a valve which automatically blocks the opening 6 of chamber 5 as soon astemperature limiter 4 has been placed in the position for cutting off the electric supply to the heating resistor 3, as shown in Figure2.

Temperature limiter4 comprises a bimetallic strip 10 (see also Figure4) which undergoes deformation in dependence on the temperature of the vapourto which it is directly exposed. Strip 10 is adapted, when deformed, to move between a position (Figure 1)wherevalve9 is held by strip 10 and releases opening 6, and a position (Figure 2) where strip 10 releases valve 9 and a return spring 11 moves valve 10 to a position where (Figure2) it blocks opening 6 of chamber Sand simultaneously moves a switch 8 into the position for cutting off the electric supply of the heating resistor 3.

In the illustrated embodiment, valve 9 is borne by a rod 12 slidingly mounted in a body 13a and extending across chamber 5 and opening 6 leading into the interior of vessel 1.

The end of rod 12 remote from valve 9 is in contact with switch 8.

The part of rod 12 in chamber 5 comprises an abutment 13 which (Figure 1) is pressed against strip 10 byareturnspring 11 when strip 10 isatatem- perature below the desired temperature.

Spring 11 mounted on rod 12 is adapted to move rod 12towards switch 8 and bring valve 9 into the position for blocking opening 6 when strip 10 releases abutment 13, as shown in Figure 2 (see also the chain-dotted position of strip 10 in Figure 4).

Switch 8 is a tumblerswitch which can be manually actuated bythe user so asto move rod 12and abutment 13 into the position for locking strip 10 and unblocking the opening 6 of chamber 5. This movement is brought about againstthe action of return spring 11.

In the embodiment shown in Figure 1, vessel 1 rests on a base 14 electrically connected to an electric supply cord 15 connected to the mains. Base 14 is electrically connected to vessel 1 by removable con nections 16,17 and 18,19.

A spring catch 20 secured to vessel 1 and adapted to be actuated by the user is for opening the electric connections 16,17; 18,19 between base 14 and vessel 1 Catch 20 is disposed in a handle 21 secured to the side of vessel 1.

Catch 20 comprises a lever 22 partly embedded in handle 21 and acted upon by a return spring 23.

Lever 22 is pivotably mounted on a shaft 24 atthe bottom of handle21 and is prolonged downwards beyond shaft 24 by a lug 25 extending substantially vertically nearthe side 7 of vessel 1.

Lug 25 bears electric connecting means 16, 18 extending substantially parallel to base 14 and connected to corresponding electric connecting means 17, 19 formed in a box 26 secured to the side of base 14.

Connections 16 borne by lug 25 comprisetwo metal pins in contact with two resilient metal strips 17 secured in box 26 and connected to the two conducting wires in cord 15.

The connection 19 in box 26 is connected to the earth wire. Connection 19 is a bent metal strip having one end engaging with friction in connection 18, which is pincer-shaped as shown in Figure 3.

In the operating position as shown in Figure 1,the connecting means 16, secured to lug 25 engage in recesses in box 26 and lock vessel 1 to base 14.

Catch 20 also co-operates with switch 8to inactivate the temperature limiter4, i.e. to cut off the electric supply to resistor 3 when the user actuates catch 20.

To this end, the top part of iever 22 has a sloping part 27 bearing against an arm 28 of switch 8.

The described kettle operates as follows: First, it is assumed thatthe kettle is in the operating position as shown in Figure 1.

In this position, the temperature limiter 4 is set, strip 10 holds valve 9 in the position away from opening 6, and resistor3 is supplied with electricity.

Vapour forming inside vessel 1 communicates with the interior of chamber 5 and escapes to the exterror via opening 29 (see Figure 4).

Whenthevapour reaches the chosen temperature, strip 10 becomes deformed and moves away from abutment 13. Spring 11 then pushes rod 12 against switch 8 and pivots it (see Figure 2) thus cutting off the electric supply to resistor 3. Valve9 simultaneously blocks opening 6, thus preventing vapour from entering chamber5.

The user can remove vessel 1 from base 14 by pressing catch 20 in the direction of arrow F as shown in Figure 2.

As soon as the user presses catch 20, switch 8 tilts into the stop position (Figure 2) thus cutting offthe electricity supply to resistor 3.

If the user continues to press catch 20 (Figure 6), the electric connections 16, 17 are released before connections 18 and 19, so thatthe phase connections can be opened while the kettle assembly is still connected to earth and without risking an electric arc, since switch 8 is in the circuit-opening position.

When catch 20 reaches the end of its travel (Figure 7), connections 16,18 of lug 25 are completelyreleased from box 26 and vessel 1 iscompletelydis- engaged from base 14.

When connections 16,17 are moving relative to 18 and 19, they undergo friction such as to maintain a slight electric contact resistance between the connections.

When the user replaces vessel 1 on base 14, he cannot re-set the temperatu re limiter 4 until catch 20 is in the inoperative position as shown in Figure 1, where connections 16, l7arecompletelyengaged in box 26.

The kettle according to the invention is therefore very safe to use.

After the hot water in the vessel has been used,the temperature limiter 4 can be immediately re-set.

Since valve 9 blocks the chamber opening 6, the bimetallic strip is no longer in contactwith the hot vapour and rapidly cools, thus very quickly returning to its normal position where it locks abutment 13, when the temperature limiter 4 is placed in the re-set position.

Claims (5)

1. An electric kettle comprising a vessel adapted to hold water and comprising a heating resistor, a temperature limiter adapted to cut offthe electric supply to the resistor when the temperature of the water vapour in the vessel reaches the desired tem perature,thetemperature limiter being disposed in a chamber communicating with the vessel interiorvia an opening formed in the top part of the vessel wall, the temperature limiter being re-settable by the user and comprising a means which automatically blocks the chamber opening as soon as the temperature limiter is placed in the position for cutting off the el ectricsupplytothe heating resistance, the kettle also comprising a bimetallic strip undergoing deforma tion in dependence on the temperature to which itis subjected, characterised in thatthe bimetallic strip is adapted when deformed to be moved between a position where the means is retainedby the strip and releases the opening, and a position where the strip releases the means and return devices move the means into a position where it blocks the chamber opening and simultaneously moves a switch into the position for cutting off the electric supply to the resistor.

2. A kettle according to claim 1, characterised in that the means comprises a rod mounted so as to be slidable through the chamber and the opening, the rod end adjacentthe opening comprising avalve adapted to blockthe opening, the other end of the rod being in contact with a switch, and the partofthe rod in the chamber comprises an abutment which bears againstthe strip when the strip is at a temperature below the desired temperature and a spring is provided for moving the rod towards the switch and bringing the rod valve to the position for blocking the chamber opening when the strip releases the abutment.

3. A kettle according to claim 1 or 2, characterised in thatthe switch is a tumbler switch actuatable by the user so as to move the means or rod into the position for locking the strip and unblocking the chamber opening.

4. A kettle according to claim 3, characterised in that it comprises a spring catch disposed in the vessel handle, the catch comprising a slope cooperating with the tumbler switch so as to inactivate the temperature limiter and cut off the electric supply to the heating resistor when the user actuates the catch.

5. An electric kettle substantially as hereinbefore described with reference to and as shown in, the accompanying drawings.