NZ199477A - Switch for electric kettle with resilient blade contact carrier - Google Patents

Description

199477 N.Z. NO.

NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION "AN ELECTRIC LIQUID HEATING APPLIANCE" We TI RUSSELL HOBBS LIMITED, a British Company of Grindley Lane, Blythe Bridge, Stoke-On-Trent, Staffordshire, ST119LN, England do hereby declare the invention, for which pray that a Patent may be granted to , and the method by which it is to be performed, to be particularly described in and by the following statement:- - 1 ~ followed by page la i 99477 1 A "AN ELECTRIC LIQUID HEATING APPLIANCE" This invention relates to an electric liquid heating appliance, and particularly but not exclusively relates to an electric kettle.

It is known to provide an electric kettle with a body shell, a heating element within the body shell and a switch housing mounted on the outside of the body shell. An on/off switch comprises a pair of resilient blades each mounting a switching contact. The contacts are relatively movable between open and closed positions by a switch operating member supported by the switch housing. In these known kettles said pair of resilient blades are supported by the switch housing and the switching contacts are physically disposed at a position remote from each end of the heating element.

According to the present invention, there is provided an electric liquid heating appliance comprising a body shell; a heating element within the body shell and having two ends which project through the body shell to the outside thereof; a switch housing mounted on the outside of the body shell; a switch comprising a single resilient blade-like electrically conductive element having two parallel finger portions integrally connected by a transverse portion, the free end of one of the finger portions being connected to one of two terminal pins, a pair of switching contacts, one of which is a fixed contact and is provided directly at one end of the heating element and the other of which is a movable contact and is provided on the free end of the other finger portion, and a switch operating member supported by the switch housing and manually operable to both close and open the switching contacts, the switch operating member being engageable with the transverse portion and/or one^or 1 994*7 ;2. ;both finger portions at a position adjacent the transverse portion for ;» ;pivoting the other finger portion about a pivot disposed between its ends hence to move the movable contact from one to the other of the open and closed position relative to the fixed contact; and a device 5 for moving the switch operating member to open the contacts when a liquid in the appliance boils. ;It is thus possible to provide an electric liquid heating appliance with a switch assembly which is simpler and cheaper to manufacture than was hitherto possible. ;10 Preferably, the appliance is provided with a temperature-protective device for moving the switch operating member to open the contacts if the heating element is not immersed in liquid and the appliance is energised. ;Conveniently, a furtherresilient blade-like electrically 15 conductive element is connected to the other of the two terminal pins and engages the other end of the heating element. ;Reference is made to the invention as described and claimed in the Applicant's New Zealand Patent Specification 199478. ;The invention will now be more particularly described, by way 20 of example, with reference to the — „ ... ;3- ;1 99477 ;accompanying drawing, wherein: ;Figure 1 is a sectional side view of a switch assembly of one embodiment of an appliance according to the invention; and ;Figure 2 is a right hand end view of part of the switch assembly shown in Figure 1. ;Referring to the drawings, there is showntherein a switch assembly for an electric kettle having a body shell 10 and a heating element 11 within the body shell 10. The heating element 11 is secured to the body shell by a fixing assembly (not shown) and the two ends of the heating element 11 (only one of which is shown) project through the body shell to the outside thereof and are sealed relative to the body shell. ;A switch assembly includes a dolly (switch operating member) 12 which can rock between a first •position - shown in full lines in Figure 1 and a second position - shown in broken lines in Figure 1. It rocks about a pivot 13 supported by a switch housing 14 and is urged into engagement with the pivot 13 by a bowed leaf spring 15 seated at one end in a recess 8 provided in the dolly and at an opposite end Ln a recess 9 provided in the switch housing 14. ;The switch assembly also includes a pair of switching contacts 16 and 17 relatively movable between open and closed positions. The contact 16 is a movable ;1 99477 ;4. ;contact mounted on a resilient blade-like electrically conductive element 18 whereas the contact 17 is a fixed contact and is provided on one of the two ends of the heating element 11. The element 18:adopts the position shown in Figure 1 in full lines in its working position and in this position the contacts 16 and 17 are closed. However, the element is movable to the position shown in Figure 1 in broken lines by a rocking movement of the dolly 12 from its first to its second position when the kettle is switched off. ;As shown in Figure 2, the element 18 has two parallel finger portions 19 and 20 integrally connected at one end by a transverse portion 21. The free end of the finger portion 19 is supported relative to the switch housing 14 and is connected to a first terminal pin 22. The movable contact ;16 is secured to the free end of the other finger portion 20. As shown, the dolly 12 engages a region of the transverse portion indicated at 23 as it rocks from its first to its second position and thus rocks the finger portion 20 about a pivot 24, supported by the switch housing 14 intermediate the ends of the finger portion 20, to the position shown in Figure 1 in broken lines, hence opening the contacts 16 and 17- VThen the dolly 12 is returned to its first position the element 18 again adopts the position shown in Figure 1 in full lines and the contacts 16 and ;17 close. ;Although the dolly 12 as described and illustrated ;1 99417 ;5. ;engages the element 18 at the region indicated at 23, it may alternatively engage any other region of the transverse portion 21 and/or one or both finger portions 19, 20 at a position adjacent the transverse portion to effect the necessary rocking movement of finger portion 20 about pivot 24. ;A second terminal pin (not shown) supported by the switch housing 14 is connected to a further resilient blade-like conductive element which contacts the other end of the heating element. ;The kettle is - of an automatic type which has a bimetal device which through the intermediary of a push rod rocks the dolly to its second position when water in the kettle boils, thereby opening the contacts 16 and 17 and hence interrupting the power supply to the heating element. ;Also, the kettle may be provided with a temperature protective device comprising a further bimetal device which is supported by the switch housing and is responsive to the temperature of the heat transmitting surfaces of the heating element to rock the dolly to. its second position in a situation in which there is . insufficient water in the kettle to cover the heating element, when the.heating element is energised. ;t ;199437 ;* 6.

In addition to a kettle as described, the invention can be applied to tea makers, coffee percolators, immersion heaters, and other kinds of electric liquid heating appliances. 7. 1 99 417

Claims (4)

WHAT WE CLAIM IS:

1. An electric liquid heating appliance comprising a body shell; a heating element within the body shell and having two ends which project through the body shell to the outside thereof; a switch housing mounted on the outside of the body shell; a switch comprising a single resilient blade-like electrically conductive element having two parallel finger portions integrally connected by a transverse portion, the free end of one of the finger portions being connected to one of two terminal pins, a pair of switching contacts, one of which is a fixed contact and is provided directly at one end of the heating element and the other of which is a movable contact and is provided on the free end of the other finger portion, and a switch operating member supported by the switch housing and manually operable to both close and open the switching contacts, the switch operating member being engageable with the transverse portion and/or one or both finger portions at a position adjacent the transverse portion for pivoting the other finger portion about a pivot disposed between its ends hence to move the movable contact from one to the other of the open and closed position relative to the fixed contact; and a device for moving the switch operating member to open the contacts when a liquid in the appliance boils.

2. The appliance of Claim 1, wherein a further resilient blade-like electrically conductive element is connected to the other of the two terminal pins and engages the other end of the heating element. 8. 199 477

3. The appliance of Claim 1 or Claim 2, having a termperature-protective device for moving the switch operating member to open the contacts if the heating element is not immersed in liquid and the appliance is energised. 5

4. An electric liquid heating appliance substantially as hereinbefore described with reference to and as shown in the accompanying drawing. TI RUSSELL HOBBS LIMITED By Their Attorneys KENRY HUGHES LIMITED