GB1559076A

GB1559076A - Electric kettle

Info

Publication number: GB1559076A
Application number: GB3445675A
Authority: GB
Original assignee: Russell Hobbs Ltd
Current assignee: Russell Hobbs Ltd
Priority date: 1976-08-13
Filing date: 1976-08-13
Publication date: 1980-01-16

Description

(54) ELECTRIC KETTLE (71) We, T. I. RUSSELL HOBBS LIMITED, formerly known as RUSSELL HOBBS LIMITED, a British Company of limited liability, of P.O. Box 1, Grindley Lane, Blythe Bridge, Stoke on Trent, Staffordshire ST 11 9LN, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment :- The present invention relates to electric kettles and other electrically-heated liquid heating or beverage making appliances incorporating immersion heating elements, all of which will hereinafter be referred to as electric kettles".

The most common failure in electric kettles is failure of the heating element, frequently caused by the kettle being switched on when there is not sufficient liquid in it to cover the heating element.

It is an object of the present invention to prevent or substantially reduce the incidence of this type of failure.

According to the present invention there is provided an electric kettle as hereinbefore defined comprising a heating element, electric circuitry, by which, in use, electricity is supplied to the element, including a manually operable ON/OFF switch which, closed, permits supply of electricity to the element said switch having a fixed contactcarrying arm and a movable contactcarrying arm, a float mounted within the liquid-containing interior of the kettle to rise and fall with the level of liquid in the kettle and drivingly connected to one end of an arm the other end of which is disposed outside the liquid-containing interior and moves between a first position corresponding to a sufficient level of liquid in the kettle interior in which the said arms of the switch are able to adopt a position in which the two contacts are in electrical connection and the said switch can be closed and a second position corresponding to an insufficient level of water in the kettle interior in which the said arms are prevented from adopting the said position and the said switch cannot be closed.

In one form of the invention the outer end portion of the arm passes horizontally through an opening in the wall of the kettle body and is rotatable about a horizontal axis coincident with the axis of the opening.

The outer end of the arm, in this form, carries a member having a cam surface that is moved on movement of the float and consequent rotation of the arm, which cam surface cooperates with the said switch permitting the switch to be closed in one rotational position of the cam surface and preventing the switch from being closed in another rotational position.

The invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a schematic rear view of part of a kettle embodying the invention; Fig. 2 is a perspective view of the part of the kettle shown in Fig. 1; Fig. 3 is a side elevation, part in section, of the rear part of a further kettle embodying the invention; Fig. 4 is a perspective rear view of the part of the kettle shown in Fig. 3; Fig. 5 is a side elevation, part in section, of the rear part of a yet further kettle embodying the invention; and Fig. 6 is a perspective rear view of the part of the kettle shown in Fig. 5.

Referring to the first embodiment, the kettle comprises a body 11 of plastics material having within its liquid-containing interior a heating-element (not shown) mounted in a wall of the body 11. Electricinty is supplied to the heating element through electric circuitry that includes an ON 10OFF switch adapted to be operated by the user of the kettle. The ON! OFF switch includes a pair of contacts 12 and 13 carried oil respective contact arms 14 and 15. The contact arm 15 is movable between a position in which the contacts I2 and 13 are closed together and electricity is supplied to the heating element and a position in which the contacts 12 and 13 are apart and no electricity can be supplied.

Movement of the arm 15 is controlled by the user of the kettle by means of a rocking dolly (not shown) in a manner well known in the art, for example as is described below with reference to the second embodiment.

A plastics float 16 is mounted within the liquid-containing interior of the body 11 on one end of an L-shaped arm 17. The other end portion 18 of the arm 17 extends horizontally (i.e. parallel to the base of the kettle) through an opening (not shown) in the wall of the body 11 and is rotatable about its longitudinal axis. A liquid-tight seal for the opening is provided by a sealing boot (not shown) disposed about the said other end portion 18 within the interior of the kettle.

An L-shaped member 22 is mounted at one of its ends on the other end 18 of the arm 17. The other end 23 of the L-shaped member 22 is of electrically insulating material and is so positioned that it can be moved into a position between the contacts 12 and 13 preventing them from being closed together. The end 23 is moved into this position by rotation of the arm 17 upon descent of the float 16 when the level of liquid in the interior of the kettle falls below a predetermined position.

A spring 24 is provided that biases the arm 17 in the downward direction of the float 16 so that the end 23 is normally held between the contacts 12 and 13.

Referring now to the second embodiment, a kettle comprises a body 211 of plastics material having within its liquidcontaining interior a heating-element (not shown) mounted in a wall of the body 211.

Electricity is supplied to the heatingelement through electric circuitry that includes an ON/OFF switch adapted to be operated by the user of the kettle. The ON/OFF switch includes a pair of contacts 212 and 213 carried respectively on a fixed contact arm 214 and a movable arm 215 biased in a direction towards the fixed contact arm 214. The switch is operated by movement of a rocking dolly 216 having a slide arm 217 that cooperates with the upper end of the contact arm 215. The dolly 216 is movable from an ON position (shown in dotted lines in Fig. 3) to an OFF position (shown in full lines in Fiz. 3) during which movement the arm 217 engages the contact arm 215 and moves it away from the arm 214 separating the contacts 212 and 213. The dolly is held positively in either its ON or its OFF position by a spring 218. When the dolly 216 moves from the OFF to the ON position, an arm 220 projecting from the dolly 216 forces the arm 215 towards the arm 214 to ensure ciosing of the contacts 212 and 213.

A plastics float 219 is mounted within the liquid-containing interior of the kettle on one end of an L-shaped arm 221, the other end portion 222 of which extends horizontally through an opening 223 in the wall of the body 211 and is rotatable therein about the longitudinal axis of the end portion 222. The opening 223 is sealed by means of a silicon-rubber sealing boot 224 disposed about the end portion 222 within the interior of the kettle and in sealing contact with the wall of the body 211.

A disc 225, having a profiled cam surface 226, is fixedly mounted on the portion 222 of the arm 221 outside the kettle body 211.

The disc 225 is arranged to rotate with the portion 222 as the arm 221 is moved by rise and fall of the float 219. The surface 226 of the disc 225 is so positioned as to cooperate with a projecting portion 227 of the movable contact arm 215. When the float 219 is in a "down" position corresponding to no, or an insufficient level of, liquid in the kettle interior, a relatively projecting portion of the surface 226 is presented to cooperate with the projecting portion 227 and the arm 215 is prevented from moving sufficiently towards the fixed arm 214 to bring the contacts 212 and 213 together. When the level of liquid within the kettle is sufficient for safe operation of the kettle, the float 219 moving to an" up" position, has caused the disc 225 to rotate so that a relatively non-projecting portion of the surface 226 is presented to cooperate with the projecting portion 227. This enables the arm 215 to move sufficiently far in the direction towards the arm 214 for the contacts 212 and 213 to be brought together. The arm 221 is biased by means of - a spring 228 towards the rotational position in which the relatively projecting portion of the surface 226 is presented to cooperate with the contact arm 215.

Referring now to the third embodiment, a kettle comprises a body 311 of plastics material having within the liquid-containing interior a heating-element (not shown) mounted in a wall of the body 311. Electricity is supplied to the heating-element through electric circuitry that includes an ON OFF switch adapted to be operated by the user of the kettle. The switch includes a pair of contacts 312 and 313 carried respectively by fixed and movable contact arms 314 and 315.

The switch includes a pivoted operating arm 316 which carries a spring 317 con nected to the upper end of the movable contact arm 315. The operating arm 316 is movable between an OFF position (shown in full lines in Fig. 5) and an ON position (shown in dotted lines in Fig. 5).

In the OFF position the movable arm 315 is held in a position in which the contacts 312 and 313 are part. As the arm 316 passes to the ON position, the arm 315 is moved to bring the contacts 312 and 313 together.

A plastics float 318 is mounted within the liquid-containing interior of the kettle on one end of an L-shaped arm 319, the other end portion 321 of which extends horizontally through an opening 322 in the wall of the body 311 and is rotatable therein about the longitudinal axis of the end portion 321. A liquid-tight seal for the opening 322 is provided by a sealing boot 323 mounted on the end portion 321 within the interior and in sealing contact with the wall of the body 311.

A disc 324, having a profiled cam surface 325, is fixedly mounted outside the body 311 on the arm 319 to rotate therewith upon rise and fall of the float 318. The cam surface 325 is so positioned as to cooperate with an adjustment screw 326 carried by the operating arm 316 when the arm 316 is moved towards its ON position. When the float 318 is in a "down" position corresponding to no, or an insufficient level of, liquid in the body 311, a relatively projecting portion of the surface 325 is presented to the screw 326 and the arm 316 is prevented from attaining a position in which the contacts 312 and 313 are brought together. When the level of liquid in the kettle is sufficient for safe operation, the float 318 will be in an "up" position and the arm 319 will be in a rotational position such that a relatively non-projecting portion of the surface 325 is presented to the screw 326. Tn this condition, the operating arm 316 can be moved fully into the ON position, allowing the contacts 312 and 313 to be brought together.

WHAT WE CLAIM IS:- 1. An electric kettle as hereinbefore defined comprising a heating element, electric circuitry, by which, in use electricity is supplied to the element, including a manuallv operable ON/OFF switch which, when closed, permits supply of electricity to the element said switch having a fixed contact-carrying arm and a movable contract-carrying arm, a float mounted within the liquid-containing interior of the kettle to rise and fall with the level of liquid in the kettle and drivingly connected to one end of an arm the other end of which is disposed outside the liquidcontaining interior and moves between a first position corresponding to a sufficient level of liquid in the kettle interior in which the said arms of the switch are able to adopt a position in which the two contacts are in electrical connection and the said switch can be closed and a second position corresponding to an insufficient level of water in the kettle interior in which the said arms are prevented from adopting the said position and the said switch cannot be closed.

2. A kettle according to Claim 1 wherein the other end portion of the arm passes horizontally through an opening in the wall of the kettle body and is rotatable about a horizontal axis coincident with the axis of the opening.

3. A kettle according to either of the preceding claims wherein the said other end of the arm carries a member the position or orientation of which is changed by rise and fall of the float and consequent movement of the said other end of the arm between the first and second positions.

4. A kettle according to Claim 3 wherein the said member is arranged on rotation of the arm to the said second position to come between the two contact-carrying arms and prevent them adopting the said contact closed position.

5. A kettle according to claim 3 wherein the said member is a disc fixed on the said other end of the arm and rotatable therewith, the disc having a cam surface which co-operates with the movable contactcarrying arm and which when the arm is in the said second position prevents the movable contact-carrying arm adopting said contact-closed position.

6. A kettle according to claim 5 wherein the contact-carrying arms are disposed vertically below the disc, which has its cam surface on one of its Bat vertically disposed faces, the movable contact-carrying arm having an upper extension which is biased to contact the said disc, so that rotation of the disc caused by the arm moving to its second position rotates the cam surface and prevents the movable contact-carrying arm adopting said contact-closed position.

7. A kettle according to Claim 6 wherein the upper extension of the movable contactcarrying arm has a portion which co-operates with a rocking dolly by which the switch is manually operated.

8. A kettle according to claim 5 wherein the movable contact-carrying arm is connected to a manually operable lever which, when moved from an OFF towards an ON position, moves the movable contactcarrying arm towards the fixed contact carrying arm, the lever having a portion which, when the lever is moved towards the ON position contacts the cam surface, the arrangement being such that in the said second position of the arm the cam surface

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. nected to the upper end of the movable contact arm 315. The operating arm 316 is movable between an OFF position (shown in full lines in Fig. 5) and an ON position (shown in dotted lines in Fig. 5). In the OFF position the movable arm 315 is held in a position in which the contacts 312 and 313 are part. As the arm 316 passes to the ON position, the arm 315 is moved to bring the contacts 312 and 313 together. A plastics float 318 is mounted within the liquid-containing interior of the kettle on one end of an L-shaped arm 319, the other end portion 321 of which extends horizontally through an opening 322 in the wall of the body 311 and is rotatable therein about the longitudinal axis of the end portion 321. A liquid-tight seal for the opening 322 is provided by a sealing boot 323 mounted on the end portion 321 within the interior and in sealing contact with the wall of the body 311. A disc 324, having a profiled cam surface 325, is fixedly mounted outside the body 311 on the arm 319 to rotate therewith upon rise and fall of the float 318. The cam surface 325 is so positioned as to cooperate with an adjustment screw 326 carried by the operating arm 316 when the arm 316 is moved towards its ON position. When the float 318 is in a "down" position corresponding to no, or an insufficient level of, liquid in the body 311, a relatively projecting portion of the surface 325 is presented to the screw 326 and the arm 316 is prevented from attaining a position in which the contacts 312 and 313 are brought together. When the level of liquid in the kettle is sufficient for safe operation, the float 318 will be in an "up" position and the arm 319 will be in a rotational position such that a relatively non-projecting portion of the surface 325 is presented to the screw 326. Tn this condition, the operating arm 316 can be moved fully into the ON position, allowing the contacts 312 and 313 to be brought together. WHAT WE CLAIM IS:-

1. An electric kettle as hereinbefore defined comprising a heating element, electric circuitry, by which, in use electricity is supplied to the element, including a manuallv operable ON/OFF switch which, when closed, permits supply of electricity to the element said switch having a fixed contact-carrying arm and a movable contract-carrying arm, a float mounted within the liquid-containing interior of the kettle to rise and fall with the level of liquid in the kettle and drivingly connected to one end of an arm the other end of which is disposed outside the liquidcontaining interior and moves between a first position corresponding to a sufficient level of liquid in the kettle interior in which the said arms of the switch are able to adopt a position in which the two contacts are in electrical connection and the said switch can be closed and a second position corresponding to an insufficient level of water in the kettle interior in which the said arms are prevented from adopting the said position and the said switch cannot be closed.

is so positioned that the amount of movement of the lever is insufficient to bring the movable contact-carrying arm into the said closed position.

9. A kettle substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings.

10. A kettle substantially as hereinbefore described with reference to and as illustrated in Figs. 3 and 4 of the accompanying drawings.

11. A kettle substantially as hereinbefore described with reference to and as illustrated in Figs. 5 and 6 of the accompanying drawings.