GB2036541A

GB2036541A - Electric kettles

Info

Publication number: GB2036541A
Application number: GB7928416A
Authority: GB
Original assignee: DH Haden Ltd
Current assignee: DH Haden Ltd
Priority date: 1978-08-17
Filing date: 1979-08-15
Publication date: 1980-07-02
Also published as: GB2036541B

Abstract

An electric kettle having a vessel wall 10, and electric immersion heater device 20 comprises an upper steam outlet 12 in the wall 10 and; the switch assembly includes a steam actuated switch 31 disposed in a chamber 41 of a body which is mounted on the vessel so as to provide a steam space 13 and a drain path 14 between the body and the vessel wall 10. The body carries an actuating mechanism 32 which includes a bimetal device 66 disposed in said steam space, which mechanism actuates the steam switch via a thrust member 44 which extends into the chamber from that side of the body which is remote from the steam space. This prevents water entering the space 13 when the kettle is filled via the spout from entering the chamber 41. The steam actuated switch may be in series with a dry overload switch 33 or be combined with a dry overload switch to share common movable contacts. <IMAGE>

Description

SPECIFICATION Improvements relating to vessels for heating liquids Improvements in or relating to electric kettles and like vessels for heating liquids.

The improvements relate particularly to an electric kettle or iike vessel of the kind having a vessel wall, and electric immersion heater device, and a switch assembly; wherein the vessel wall has a lower aperture through which the heater device extends and an upper steam outlet; wherein the switch assembly includes a steam actuated switch and a body; wherein the body is mounted on the vessel so as to provide a steam space between an upper part of the body and a portion of the vessel wall adjacent the steam outlet; and wherein the steam actuated switch is actuated via an actuating mechanism which includes a bimetal device disposed in said steam space, a vessel of this kind being hereinafter referred to as a "vessel of the aforesaid kind" for the sake of brevity.

It is usual in vessels of the aforesaid kind to dispose the steam outlet adjacent to the lid of the vessel, so that, when the contents of the vessel boil, steam issues from the steam outlet to heat the bimetal device to move a thrust member of the actuating mechanism. However, the thrust member extends through a way in the upper part of the body, which part presents an obstruction to moisture reaching the steam actuated switch. Even if the vessel is overfilled inadvertently, any water escaping via the steam outlet can only do so at a rate and pressure insufficient generally to overcome said obstruction.

Such switch,assemblies and actuating mechanisms are not suitable for use with spout filled lidless vessels, because such vessels are tilted during filling thereby lowering the steam outlet relative to the spout, so that any excess water can escape via the steam outlet at a rate and pressure sufficient to traverse said way and penetrate into the steam actuated switch.

One obvious expedient to prevent such flooding is to provide the steam outlet with a small snorkel or other valve closed by a buoyant body, but this expedient has disadvantages if the vessel is to be used to heat hard water or water/solids mixtures or solutions.

According to the present invention there is provided a vessel of the aforesaid kind wherein said steam space extends downwards to a liquid overflow drain path; wherein the steam actuated switch is disposed in an internal chamber; wherein said actuating mechanism extends to that side of the upper part of the body which is remote from the steam space and includes a thrust member which enters the internal chamber from that side of the body whereby to prevent any water entering the steam space from entering said internal chamber when the vessel is filled via a spout of the vessel.

Said body preferably comprises a main moulding having an upper part, to support the bimetal device, and a lower part which defines a recess; and comprises a carrier moulding located in said recess. The carrier moulding is preferably provided with conductors to connect electrically electric input terminals mounted on the carrier moulding with the steam actuated switch and with the immersion heater device.

The vessel preferably incorporates a dry overload switch located by the body so that a dry overload bimetal is held against a hot spot of the immersion heater device, and said dry overload switch preferably incorporates a further thrust member which extends away from said dry overload bimetal to actuate a movable contact of said switch assembly.

In one embodiment the vessel preferably has a spacer moulding which forms part of the body and is clamped between the rest of the body and a head of the immersion heater device, and the dry overload switch and the steam actuated switch preferably incorporated contacts common to both switches. In a second embodiment the body is provided with an annular abutment which abuts the vessel wall or a seal thereon to space the rest of the body away from the vessel wall, and the steam and dry overload switches preferably have respective movable contacts and are connected in series the dry overload switch being disposed in a further chamber.

Both embodiments are arranged so that if the vessel is tilted to cause water to flood around the switch assembly, the electrically conductive parts of the switch assembly remain dry.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein Figure 1 shows, in vertical cross section, a first embodiment of a vessel according to the invention, which vessel incorporates a first form of switch assembly; Figure 2 shows the switch assembly, incorporated into the vessel shown in Figure 1, in part sectional rear elevation; Figure 3 shows, in vertical cross section, a modification of part of the switch assembly shown in Figures 1 and 2; Figure 4 shows, in vertical cross-section, part of a second embodiment of vessel of the invention, incorporating a second form of switch assembly, with a handle and cover removed; Figure 5 shows a rear elevation of the switch assembly shown in Figure 4;; Figure 6 shows a lower portion of the switch assembly in horizontal cross section on a line VI-VI shown in Figure 5; Figure 7 shows an inside face of a carrier moulding incorporated into the second form of switch assembly; and Figures 8 and 9 are part cross sectional views of part of the lower portion corresponding respectively to lines VIII-VIII and IX-IX in Figure 7.

The vessel in both embodiments is an electric kettle of lidless spout filled form having a vessel wall 10 and a handle 11. The vessel wall has an upper steam outlet 12 and a large lower aperture through which an immersion heater device 20 extends. A head 21 of the device 20 is secured to the wall 10so as to clamp a seal 22 between the head 21 and the wall 10 as hereinafter described.

Referring to Figures 1,2 and 3, the first form of switch assembly generally comprises a body 30, a steam actuated switch 31, an actuating mechanism 32 and a dry overload switch 33. The body 30 is an assembly of three mouldings, namely a main mould ing 34, a closure moulding 35 and a carrier moulding 36. The steam and dry overload switches are con nected in series by conductors as hereinafter described.

The upper part of the main moulding 34 has a hood 37 which shrouds the outlet 12, carries the actuating mechanism 32, and serves to define a steam space 13 between itself and the wall 10. In this embodiment the lower part of the main moulding has an annular abutment 38 which abuts the wall 10 to space the rest of the main moulding away from the wall 10 to leave a drain path 14 around the abutment 38 to a bottom opening 16 in a switch cover 15.

The body 30 is provided with an internal chamber 41 which is formed by part of a recess in the main moulding and is substantially closed by the closure moulding 35 on which the fixed and movable contacts 42 and 43 of the switch 31 are mounted, so as to be separable by a thrust member 44 which extends into the chamber from that side of the body which is remote from the steam space 13. The rest of the recess extends within the annular abutment 38 and is occupied by the carrier moulding 36.

The lower part of the body is secured to the head 21 of the immersion heater device 20 by threaded fasteners 46 which extend through the main and carrier mouldings, to locate the latter in the recess in engagement with a shoulder of the head 21 which projects through the wall 10 and to clamp the seal 22 and a sealing ring 45 in position to seal the joints between the head 21, wall 10, abutment 38 and carrier moulding 36, so that the carrier moulding and head define a second chambertherebetween. The seal 22 and ring 45 have flats to match flats on the head 21 and abutment 38, and a similar flat 47 is provided on the carrier moulding 36 (Figure 6), for mutual aligment and location.

The carrier moulding 36 carries live, earth and neutral terminal pins 48,49 and 50, provides a plug socket 51 to shroud these terminal pins, carries conductors comprising a live to dry overload connector 52, a neutral to cold tail connector 53, a dry overload to steam switch connector 54, a steam switch to cold tail connector 55, an earth to head connector 56; and serves to clamp the dry overload switch 33 in a hot spot thimble 23 of the head within the second chamber. The switch 33 is an assembly which comprises a housing containing parts shown in broken lines, in which parts include a dry overload bimetal 57, a movable contact 58, a fixed contact 59 and a further thrust member 60 located slidably, between the bimetal 57 and a resilient conductor carrying the movable contact 58, by an insulating heat resistant member 61.The heater device 20 has cold tails 24 which engage the connectors 53 and 55 in sockets 62 provided in the carrier moulding.

The actuating mechanism 32 generally comprises a lever 63 pivotally rockable between stable off and on positions, an over centre spring 64 to hold the lever in the on position (as shown) or in the off position, a pivot 65 mounted on the upper part of the main moulding 34 to carry the lever 63, a bimetal device 66 or 66A to displace the lever to the off position when heated by steam. In the form shown in Figure 1 the bimetal device 66 is located upon the hood 37 to lie in the steam space to act on an adjustable upper thrust member 67 carried by the lever 63 to extend through the main moulding 34, but in the form shown in Figure 3, the bimetal 66A extends upwards around the hood 37 to act on an upper extension 68 of the lever 63.

The lever 63 projects through the cover 15 so as to be manually operable between said off and on positions. In the off position the lever abuts and displaces the thrust member 44 to separate the contacts 42 and 43.

The second form of switch assembly shown in Figures 4 to 9 generally comprises a body, a steam actuated switch having an actuating mechanism 70 and a thrust member 71, and a dry overload switch 72.

The body is an assembly of three moulding, a main moulding 73, a carrier moulding 74 and a spacer moulding 75, which assembly is secured to the head 21 as hereinafter described.

The head 21, in this embodiment is provided with a metal support member 25, which extends rearwards towards the body, and a cylindrical extension 26 which is externally threaded to receive a fastener ring 27 for clamping the wall 10 of the kettle between the seal 22 and the fastener ring in known manner to secure the device 20 to the kettle.

The support member 25 is of elongate form and is formed to serve as a socket for a fastener 76.

The spacer moulding is an insulating heat resistant plastics member and is shaped to fit closely within the extension 26 and around the support member 25. The spacer moulding is apertured to provide two ways 77 through which the cold tails 24 extend and a guidewaythrough which extends a furtherthrust member 78 of the switch 72; and is shaped to provide a mounting for a bimetal 80 of dished circular snap acting form. The bimetal 80 is peripherally located on the mounting by a cyiindrical flanged metal retainer 81 which is a push fit around a peripheral surface of the mounting. The retainer 81 may have a lug (not shown) which can be bent over around a shoulder on the spacer moulding to retain the bimetal in position on the spacer moulding.

The carrier moulding 74 is shaped peripherally to fit closely in the extension 26; has an exterior or rear face from which live and neutral pins 82 and 83 project; and has an inside face (Figure 7) which is shaped to inter-engage with the spacer moulding 75 in a predetermined mutual orientation to define therewith an internal chamber to receive resilient conductors 84 and 85 and a fixed conductor 86.

Stepped openings 87 are provided in the carrier moulding to receive the cold tails 24, part cylindrically curved portions 88 of the conductors 84 and 86 and fasteners 89, which fasteners close the openings and clamp the portions 88 to the cold tails 24. The carrier moulding is moulded to include short pegs 90 upon which the conductors 84 and 85 are located during assembly, the pegs 90 being heated under pressure thereafter to form heads thereon to retain the conductors in position. Further pegs 91 are provided which are engaged in sockets in the spacer moulding 75, which pegs are headed during assembly of the switch assembly to retain the spacer and carrier mouldings together.The live and neutral pins 82 and 83 have stepped hollow ended extensions 92 which extend through the carrier moulding and are rivetted or swaged so as to be secured to the conductors 85 and 86 whereby to secure the latter and the pins 82 and 83 in position. Separable movable contacts 93 are provided on the conductors 84 and 85 which contacts 93 are common to the dry overload and steam actuated switches. The further thrust member 78 acts on the conductor 85.

An earth pin 94 has a foot 95 which is clamped rigidly to the support member 25 by the fastener 76, so that the foot bears against the bottom of a further opening in an outside or rear face of the carrier moulding to urge the latter and the spacer moulding towards the head 21 so as to thrust the bimetal 80 against the hot spot 23.

The rear or outside face of the carrier moulding 74 engages in a recess provided in a lower part of the main moulding 73. A peripheral surface 97 of the carrier moulding extends between and forms a seal between said lower part and the extension 26, and terminates at a sealing flange 98 which sealingly engages the spacer moulding around said chamber.

The lower part provides an annular channel 99 around the recess, into which channel 99 the ring 27 projects so as to shroud the surface 97 and define a moisture draining path 100 therebetween, which path 100 leads to a bottom drain 101 let into the bottom ofthe channel 99.

The lower part is secured to the carrier moulding, by two fasteners 102 which are received in blind sockets, so as to close the openings 87 and to cover the further opening in the carrier moulding. A plug socket 103 extends rearwards from the lower part to shroud the live, neutral and earth pins which project through close fitting ways in the lower part.

The main moulding has an upper part 104 which extends upwards to a hood 105 which overlies the steam outlet 12 and carries a steam actuated bimetal 106 so that the latter extends downwards within a steam space 13 defined between the wall 10 and the upper part 104. The steam space 13 extends downwards to a liquid drain path 14 around the ring 27 between the body and the wall 10.

The actuating mechanism 70 includes a lever 107 having a knob 108 which projects through the cover (not shown), a lower portion which encircles the plug socket 103 and is pivotally carried thereon by two co-axial pivots 109, and a bottom part 110 which is disposed below the socket 103 for actuating the thrust member 71. The knob 108 extends to engage an over centre spring 111 which abuts the upper part 104, and extends from that side of the body which is remote from the steam space 13 into the steam space through an opening 112 in the part 104 for actuation by the bimetal 106. The thrust member 71 is disposed below the socket 103 and extends slidably into said chamber through close fitting ways in the lower part of the main moulding 73 and the carrier plate 74 for actuating the switch contacts 93 by abutting and moving the conductor 84.

The cover is secured to the main moulding by means of fasteners inserted into blind sockets 113 in the main moulding.

In use, if the hot spot reaches a predetermined temperature, the dry overload bimetal moves rapidly from a convex to a concave shape, thereby displacing thefurtherthrust member so thatthe latter abuts and moves the conductor 85 to separate the contacts 93 and break the electrical circuit from the live pin to the element.

When the vessel boils, steam from the opening 12 will cause the bimetal 106 to bend outwards displacing the lever 107 from the on position shown to an off position, thereby moving the thrust member 71 forwards to abut and move the conductor 84 to open the contacts 93. The lever is stable only in the on and off position.

It will be readily appreciated that the contacts operate in a closed or substantially closed chamber so as to be protected from dirt, which chamber is separated from the hot spot by the spacer plate and the bimetal device.

The invention is not confined to the precise details of the foregoing examples. For example, other forms of bimetal, e.g. rectangular or elongate, or snap or progressively acting, can be used, and the fasteners 89 may be in the form of spring clips.

Claims

1. Avessel of the aforesaid kind wherein said steam space extends downwards to a liquid overflow drain path; wherein the steam actuated switch is disposed in an internal chamber; wherein said actuating mechanism extends to that side of the upper part of the body which is remote from the steam space and includes a thrust member which enters the internal chamber from that side of the body whereby to prevent any water entering the steam space from entering said internal chamber when the vessel is filled via a spout of the vessel.

2. Avessel as claimed in claim 1, wherein said body comprises a main moulding having an upper part, on which said bimetal device is supported, and a lower part which defines a recess.

3. Avessel as claimed in claim 2, wherein said actuating mechanism comprises a lever pivotally mounted on said main moulding at that side of the body which is remote from the steam space, so as to be rockable to move the thrust member.

4. A vessel as claimed in claim 2 or 3, wherein said carrier moulding of the body is located in said recess; and wherein said carrier moulding carries live and neutral electrical input terminal pins and conductors to connect said terminal pins with the steam actuated switch and the immersion heater device.

5. A vessel as claimed in any preceding claim incorporating a dry overload switch located by the body so that a dry overload bimetal is held against a hot spot of the immersion heater device; wherein said dry overload switch incorporates a further thrust member which extends away from said dry overload bimetal to actuate a movable contact of said switch assembly.

6. Avessel as claimed in claim 5, as appended to claim 4, wherein the movable contact is mounted on said carrier moulding and is disposed at that side of the carrier moulding which faces the hot spot.

7. A vessel as claimed in claim 5 or 6 wherein the furtherthrust member is located slidably by an insulating heat resistant member.

8. A vessel as claimed in claim 7, wherein the heat resistant member is a spacer moulding which forms part of the body and is clamped between the rest of the body and a head of the immersion heater device.

9. A vessel as claimed in claim 5 or any one of claims 6 to 8 as appended to claim 5, wherein the dry overload switch and the steam actuated switch incorporate contacts common to both switches, and wherein said thrust member and said further thrust member both extend into said chamber for actuation of said contacts.

10. Avessel as claimed in claim 9, as appended to claims 4 and 8, wherein said chamber is defined between said spacer and carrier mouldings, and wherein said conductors are secured to said carrier moulding within said chamber.

11. Avessel as claimed in claim 10, wherein a peripheral surface of said carrier moulding extends from said main moulding to said head to serve as a seal therebetween; wherein said peripheral surface is shrouded by a fastener ring engaging around the head; and wherein a moisture draining path to a bottom drain is provided between said fastener ring and said peripheral surface.

12. A vessel as claimed in claim 4 or any preceding claim as appended to claim 4, wherein the input terminal pins extend through the carrier moulding and through the main moulding to terminate within a plug socket provided by the body.

13. Avessel as claimed in claim 12, as appended to claim 9, wherein said plug socket is provided on the main moulding; and wherein the thrust member extends through the main moulding below said socket.

14. Avessel as claimed in claim 13, as appended to claim 3, wherein said lever extends around and is pivotally mounted on said plug socket.

15. Avessel as claimed in any one of claims 1 to 7, wherein the body is provided with an annular abutment which abuts the vessel wall or a seal thereon to space the rest of the body away from the vessel wall.

16. Avessel as claimed in claim 15, as appended to claim 5, wherein the steam and dry overload switches have respective movable contacts and are connected in series; wherein the dry overload switches have respective movable contacts and are connected in series; wherein the dry overload switch is disposed in a further chamber; and wherein the annular abutment extends around said further chamber.

17. Avessel as claimed in claim 14 or 15, as appended to claim 4, wherein the carrier moulding is provided with a plug socket which extends through the main moulding to project from that side, and wherein the terminal pins extend to within said plug socket.

18. A vessel substantially as hereinbefore described with reference to Figures 1 and 2; Figures 1 and 2 as modified by Figure 3, Figures 4,5 and 6; or Figures 4 to 9 of the accompanying drawings.