GB2408918A

GB2408918A - Attachment of heaters in liquid heating vessels

Info

Publication number: GB2408918A
Application number: GB0424657A
Authority: GB
Inventors: Alan Michael George Meeks; Michael James Scott
Original assignee: Strix Ltd
Current assignee: Strix Ltd
Priority date: 2003-11-12
Filing date: 2004-11-08
Publication date: 2005-06-15
Anticipated expiration: 2024-11-08
Also published as: GB0326383D0; GB2408918B; CN2783899Y; GB0424657D0

Abstract

A liquid heating vessel comprises a vessel body 2 having an opening in the base thereof and a heater 14 adapted to close said opening. The vessel body comprises a downwardly depending wall portion 12 and the heater comprises a corresponding wall portion 16 arranged such that in use it overlaps the downwardly depending vessel wall portion 12. The vessel further comprises means such as a strap for removably clamping the heater 14 to the vessel body by selectively exerting a circumferential compressive force on the respective wall portions of the heater and body 12,16 in the region in which they overlap. The strap may be received in a groove 28 of a member 22 which supports an annular L-shaped seal 20. The strap may be tightened by an over-centre lever arrangement operable by means of a handle 34. Means may be provided to interrupt electrical supply to the heater if the proper compressive force is lacking. The vessel body 2 may be of glass.

Description

240891 8 Attachment of Heaters in Liquid Heating Vessels This invention

relates to the attachment of heaters to liquid heating vessels, particularly for boiling water and particularly those made of glass.

In recent years liquid heating vessels having a heated base and thus no element protruding into the interior of the vessel have become extremely popular.

Part of the reason for this is that such vessels are easier to clean - e. g. to remove limescale. However, popular "bullet" designs for hot water jugs which are particularly popular can make cleaning more difficult as a result of their narrower neck portions.

The need to be able to keep liquid heating vessels clean is particularly important in view of the recent trend for glass-bodied jugs.

The Applicants have appreciated that it would be desirable to be able to remove the glass body of the jug from the heater so that the former may simply be placed in a dishwasher for cleaning. Indeed, an example of a previous proposal by the Applicant may be seen in GB-A- 2363700. There remains a need, however, for an alternative arrangement which allows for quick and easy removal of a vessel body whilst still giving a satisfactory seal in use.

When viewed from a first aspect the present invention provides a liquid heating vessel comprising a vessel body having an opening in the base thereof and a heater adapted to close said opening wherein said vessel body comprises a downwardly depending wall portion and said heater comprises a corresponding wall portion arranged such that in use it overlaps the downwardly depending vessel wall portion, the vessel further comprising means for removably clamping said heater to said vessel body by selectively exerting a - 2 circumferential compressive force on the respective wall portions in the region of said overlap.

When viewed from a second aspect the present invention provides a heater assembly adapted to close an opening in the base of a liquid heating vessel which has comprises a downwardly depending wall portion, wherein said heater assembly comprises a wall portion arranged such that in use it overlaps the downwardly depending vessel wall portion, and means for removably clamping said heater to said vessel body by selectively exerting a circumferential compressive force on the respective wall portions in the region of said overlap.

Thus it will be seen by those skilled in the art that in accordance with the invention a removable compressive force is applied laterally to the wall portions to clamp them together. To remove the heater from the vessel body, the compressive force may simply be removed or reduced.

The invention may be applied to provide benefit with metal or plastics bodied vessels, but preferably the body is substantially of glass. By removing the compressive force, the heater may then be removed from the glass body and the latter may be routinely cleaned e.g by placing it in a dishwasher.

In some preferred embodiments a seal is provided between the downwardly depending portion of the vessel wall and the heater wall portion. Such a seal will therefore be clamped between the two wall portions in use to provide a water tight seal. Additionally or alternatively a seal is provided between the clamping means and the vessel or heater wall portion. Providing a seal between the clamping means and a glass vessel wall portion is particularly preferred since it means that a force may be applied to the seal without deflection of the wall. In one preferred embodiment the seal has a generally U-shaped section and is fitted over the edge of the vessel depending wall portion. l 3

The means for providing the compressive force could take a number of possible forms but preferably comprises a strap encircling the two wall portions and means for tightening the strap to provide said compressive force.

Many different forms of the means for tightening the strap are possible. For example, a worm drive mechanism could be used similar to that found in a jubilee clip.

Another possibility would be to use a ratchet mechanism.

Preferably, however, the strap tightening means comprises an over-centre lever arrangement for tightening the strap. In particularly preferred embodiments, one end of the strap is attached to a kinked portion of the lever to amplify the movement of the lever, thereby increasing the tightening force which may be applied to the strap.

The heater wall portion could sit radially outwardly of the downwardly depending vessel wall portion in use but preferably the vessel wall portion is outermost of the two. This allows the size of the heater to be minimised thereby saving costs.

The strap or other compressive means could act directly on the outermost of the two wall portions but preferably an intermediate carrier is provided. This is advantageous since the carrier can be provided with means for locating the strap in the required region of overlap of the two wall portions. The carrier preferably comprises a plurality of tabs separated by gaps which allows the carrier to be easily compressed in a circumferential direction and therefore transmit the compressive force to the wall portions. Most preferably means are provided between the carrier and the outermost wall portion (which is preferably the depending vessel wall portion) to prevent the strap and/or carrier from slipping off. A suitable friction surface could be provided on the inward face of the carrier but is preferably provided as an integral moulding with a seal between the vessel and heater wall portions. This seal preferably also functions to prevent leakage of liquid from the vessel. In preferred embodiments a user operable mechanism is provided for tightening and loosening the strap. This allows for quick and simple separation of the vessel body from the heater to allow the former to be cleaned but could also make it easy for a user to gain direct access to the energised heater.

In accordance with a further preferred feature of the invention therefore, there is provided means for interrupting the electrical power supply to the heater in the event that the compressive force clamping the heater to the vessel body is removed or reduced.

Preferably such means comprises an actuating arm acting to open a set of contacts to interrupt the power supply to the heater, e.g. by acting on the trip level of a thermally sensitive control unit such as the Applicant's U18 series of controls.

Additionally or alternatively a means is provided for interrupting the electrical power supply to the heater in the event that the vessel body is removed from the heater. Such a feature could be implemented in may possible ways, but in the presently preferred embodiment there is provided a resiliently biased member held in use against said resilient bias by a portion of the vessel body but arranged to act under said bias to interrupt the electrical supply to the heater in the event that the vessel body is removed from the heater.

Again, most preferably such a member is arranged to act on the trip lever of a control unit such as that of the Applicants U18 series of controls.

Both of the aforementioned features, separately or combined, enhance the safety of the vessel by automatically switching off the heater when the vessel body is loosened and/or removed and preventing it from being reenergised until the vessel body has been replaced and/or is properly clamped.

Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a perspective cutaway view, with an enlarged portion, of a glass bodied liquid heating vessel in accordance with the present invention; Fig. 2a is a cutaway perspective view with enlarged portion showing a heater, seal, strap and strap carrier arrangement as used in the vessel of Fig. 1; Fig. 2b is a complete perspective view of the arrangement shown in Fig. 2a; Fig. 2c is an exploded view of the arrangement in Figs. 2a and 2b; Fig. 3 is a perspective cutaway view, with enlarged portion, showing a strap tightening mechanism; Fig. 4 is a cutaway perspective view from underneath, with enlarged portion, showing the strap loosened; Fig. 5 is a perspective cutaway view showing the glass body attached to the heater; Fig. 6 is a view similar to Fig. 6 with the glass body removed from the heater; and Fig. 7 is a view similar to Fig. 1 showing a second embodiment.

Turning to Fig. 1, there may be seen a liquid heating vessel in accordance with the invention. The vessel comprises a dome-shaped body 2 made of glass having a spout 4 in the upper region thereof. A handle 6 is integrally moulded with a neck collar 8 fitted to the neck of the body 2 to allow the vessel to be lifted and carried.

As may be seen most clearly from the enlarged portion of Fig. 1, the glass body 2 has an inwardly returning portion 10 and a wall portion 12 depending downwardly from that. A slightly thickened bead 12a is provided at the peripheral edge of the downwardly depending wall portion.

A generally planar heater 14 is fitted to close the 6 - opening in the glass body 2. This could be of the sheathed underfloor type or the thick film type, both of which are well known in the art. As may be seen more clearly in Fig. 2c, the heater 14 is generally planar but has a peripheral downwardly extending wall 16 terminating in a shallow outer trough 18. The downwardly depending vessel wall portion 12 overlaps the heater wall portion 16 with the peripheral bead 12a of the vessel wall sitting in the trough 18 of the heater.

An annular L-shaped seal 20 is shaped so as to fit underneath the heater trough 18 with the vertical part returning inwardly to lie against the glass vessel wall portion 12. An annular seal support member 22 has a similar cross-sectional profile to the seal 20 and is located beneath and radially outwardly of the seal 20.

On its lower face, the seal support member 22 defines a groove which receives the upper edge of an internal upstanding wall 24 that forms part of a base cover moulding 20.

The vertical outer face of the seal support member 22 defines a rectangular channel 28 which in use receives a strap 30 (described in greater detail herein below). As may be seen most clearly in Fig. 2c, the seal support member 22 is divided circumferentially into a series of vertical tabs 32 with vertical gaps in between them so that they may flex independently of one another.

Also visible in Fig. 1 is a body release handle 34 whose function will be described later. Turning to Figs. 2a to 2c, the function of the strap 30 may be seen. The strap 30 extends around the circumference of the heater 14, seal 20 and seal support member 22 and is received in the rectangular grooves 28 in the vertical tabs 32 of the seal support member 22. Focusing on the enlarged portion of Fig. 2a, it will be seen that one end of the strap 30 is formed as a yoke 36. The arms of 7 - the yoke 36 each receive the shaft of a crank lever 38 to which the opposite end of the strap 30 is attached.

The end of the strap 30 is attached to a kinked portion 40 off set from the main axis of the crank lever 38. Thus as the crank lever 38 is rotated about its axis, the kinked portion 40 executes an arc relative to this axis. The effect of this is to vary the circumference circumscribed by the strap 30 by a distance equal to twice the off set of the kinked portion 40 from the main axis of the crank lever 38.

The circumference circumscribed by the strap 30 is at a minimum when the crank lever 38 is in the position shown in Figs. 2b and 2c. When it is rotated 90 clockwise to the position shown in Fig. 2a, however, the circumference circumscribed is increased. Thus by judicious choice of the length of the strap 30, it may be arranged that when in the position shown in Figs. 2b and 2c, a circumferential compressive force is applied to the seal support member 22 and hance transferred to the seal 20 and the vessel and heater wall portions 12, 16. It will be appreciated by considering Fig. 1 again, that the strap 30 can therefore be used to apply a circumferential clamping force to clamp the heater 14 to the vessel body 2.

As is seen most clearly in Figs. 3 and 4, the lower part of the crank lever 38 is received in the hub 42 of the body release handle 34. Thus by turning the handle 34 about its hub 42, the circumferential clamping force may be applied and removed.

Fig. 3 shows the handle 34 in its normal operating position in which the strap 30 is tightened around the tabs 32 of the seal support member to clamp the tabs 32, the seal 20 and the downwardly depending vessel wall portion 12 against the heater wall portion 16. The corresponding view of the whole vessel is shown in Fig. 5. When it is desired to remove the body for cleaning, however, the handle 34 may be rotated clockwise (when 8 viewed from above) by approximately 90 or so to loosen the strap 30 as shown in Fig. 4. The corresponding view in Fig. 6 shows that with the clamping force thereby removed, the glass body 2 may be removed from the heater assembly and washed easy by placing in a dishwasher.

Once the glass body 2 has been washed, it may simply be placed into the annular groove between the metal heater wall 16 and the vertical wall of the seal and the handle 34 rotated back to re-tighten the strap 30 and thereby apply a clamping force to the heater wall 16 and the vessel depending wall portion 12 in the region in which they overlap. The vessel may once again then be used for boiling water.

It will further be seen in Figs. 2a to 2c, Fig. 3 and Fig. 4 that the crank lever 38 is bent radially outwardly to form a projecting arm 44. When the handle 34 is in its normal operating position as shown for example in Fig. 3 and Fig. 5, the projecting arm 44 is approximately tangential to the vessel body 2 and heater and performs no function. When the handle 34 is rotated in order to loosen the strap 30 however, the projecting arm 44 swings around and underneath the heater 14. This is shown particularly in Fig. 4. It will be seen that as the projecting arm swings under the heater, it engages the trip lever 46 of the Applicant's U18 thermally sensitive control unit from below. The movement of the projecting arm 44 is such as to lift the trip lever 46 from beneath thereby causing it to go over- centre and open the electrical contacts in the control unit. This causes the power supply to the heater 14 to be interrupted.

The trip lever 46 is also attached to an external on/off knob 48. Thus if a user should attempt to remove the vessel body 2 whilst the heater is energised, it will automatically be switched off. Furthermore, the projecting arm 44 acts as a solid lock underneath the trip lever 46 to prevent power being restored to the heater until the handle 34 has been returned to its stowed position in which the strap 30 is tightened, as shown in Figs. 3 and 5.

Another safety mechanism is visible in Figs. 3, 5 and 6. Turning firstly to Fig. 3, it may be seen that the on/off knob moulding 48 is provided with an integrally moulded upwardly projecting hook 50. The end of the hook 50 is located over the horizontal arm 52 of an L-shaped push-rod member 54. The longer, vertically extending arm 56 of the push member is resiliently biased against the return portion 10 of the glass body by a compression coil spring 58.

The arrangement is such that when the glass body 2 is removed as shown in Fig. 6, the push-rod 54 is moved upwardly by the coil spring 58 thereby forcing up the hook projection 50 and pushing the trip lever 46 over centre to trip the control unit off. Therefore removing the glass body 2 from the heater 14 will also have the effect of automatically interrupting power to the heater. Thus either loosening the compressive sealing force by rotating the handle 34 from its normal, stowage position, or removing the glass body 2 from the heater 14, will cause power to be automatically cut off. It is thus impossible for the heater 14 to be energised inadvertently unless the glass body 2 is properly clamped in place.

A second embodiment of the invention is shown in Fig. 7. In this embodiment the heater 60 does not have a trough but rather is formed with a peripheral ledge 62 downwardly offset from the main plane of the heater.

Also, the seal 64 is generally U-shaped to fit over the depending vessel wall portion 12. The seal support 66 in this embodiment is fitted over the peripheral ledge 62 of the heater as in the previous embodiment, it comprises a circumferential series of independent vertical tabs 68 each of which is shaped to receive and locate the strap 30. It will be appreciated that in this embodiment there is greater thermal isolation between the heater 60 and the vessel wall 12 which may be advantageous in some circumstances.

It will be appreciated by those skilled in the art that the above description simply gives examples of some embodiments of the invention and is not exhaustive. For example, it is not essential to use a strap to apply a compressive force but any other suitable means could be used such as a worm drive. - 11

Claims

Claims: 1. A liquid heating vessel comprising a vessel body having an

opening in the base thereof and a heater adapted to close said opening wherein said vessel body comprises a downwardly depending wall portion and said heater comprises a corresponding wall portion arranged such that in use it overlaps the downwardly depending vessel wall portion, the vessel further comprising means for removably clamping said heater to said vessel body by selectively exerting a circumferential compressive force on the respective wall portions in the region of said overlap.
2. A vessel as claimed in claim 1 wherein said body is substantially of glass.
3. A heater assembly adapted to close an opening in the base of a liquid heating vessel which has a downwardly depending wall portion, wherein said heater assembly comprises a wall portion arranged such that in use it overlaps the downwardly depending vessel wall portion, and means for removably clamping said heater to said vessel body by selectively exerting a circumferential compressive force on the respective wall portions in the region of said overlap.
4. A vessel or heater assembly as claimed in claim 1, 2 or 3 comprising a seal arranged to be clamped between the vessel and heater wall portions in use to provide a water tight seal.
5. A vessel or heater assembly as claimed in any preceding claim comprising a seal arranged in use between the clamping means and the vessel wall portion.
6. A vessel or heater assembly as claimed in any preceding claim comprising a seal arranged in use between the clamping means and the heater wall portion.
7. A vessel or heater assembly as claimed in claim 6 when dependent upon claim 5 wherein said seal has a generally U-shaped section and is fitted or arranged to be fitted over the edge of the vessel depending wall portion.
8. A vessel or heater assembly as claimed in any preceding claim wherein the means for providing the compressive force comprises a strap encircling or for encircling the vessel and heater wall portions and means for tightening the strap to provide said compressive force.
9. A vessel or heater assembly as claimed in claim 8 wherein said means for tightening the strap comprises an over-centre lever arrangement.
10. A vessel or heater assembly as claimed in claim 9 wherein one end of the strap is attached to a kinked portion of the lever.
11. A vessel or heater assembly as claimed in any preceding claim wherein the vessel wall is or is arranged to be radially outwardly of the heater wall portion in use.
12. A vessel or heater assembly as claimed in any preceding claim comprising a carrier between the strap or other compressive means and the vessel or heater wall portion.
13. A vessel or heater assembly as claimed in claim 12 wherein the carrier comprises means for locating the strap or other compressive means in the region of overlap of the vessel and heater wall portions.
14. A vessel or heater assembly as claimed in claim 12 or 13 wherein carrier comprises a plurality of tabs separated by gaps.
15. A vessel or heater assembly as claimed in claim 12, 13 or 14 comprising a seal between said carrier and said vessel or heater wall.
16. A vessel or heater assembly as claimed in claim 15 wherein said seal also functions to prevent leakage of liquid from the vessel.
17. A vessel or heater assembly as claimed in any preceding claim comprising a user operable mechanism for tightening and loosening said means for clamping said heater to said vessel body.
18. A vessel or heater assembly as claimed in any preceding claim comprising means for interrupting the electrical power supply to the heater in the event that the compressive force clamping the heater to the vessel body is removed or reduced.
19. A vessel or heater assembly as claimed in claim 18 wherein said means for interrupting power comprises an actuating arm acting to open a set of contacts to interrupt the power supply to the heater.
20. A vessel or heater assembly as claimed in claim 19 wherein said actuating arm is arranged to act on the trip level of a thermally sensitive control unit.
21. A vessel or heater assembly as claimed in any - 14 preceding claim comprising means for interrupting the electrical power supply to the heater in the event that the vessel body is removed from the heater.
22. A vessel or heater assembly as claimed in claim 21 comprising a resiliently biased member held in use against said resilient bias by a portion of the vessel body but arranged to act under said bias to interrupt the electrical supply to the heater in the event that the vessel body is removed from the heater.
23. A vessel or heater assembly as claimed in claim 22 wherein said member is arranged to act on the trip lever of a control unit.
24. A vessel or heater assembly substantially as hereinbefore described with reference to the accompanying drawings.