GB2385718A

GB2385718A - Liquid heating appliances

Info

Publication number: GB2385718A
Application number: GB0204492A
Authority: GB
Inventors: John Crawshaw Taylor
Original assignee: Strix Ltd
Current assignee: Strix Ltd
Priority date: 2002-02-26
Filing date: 2002-02-26
Publication date: 2003-08-27
Anticipated expiration: 2022-02-26
Also published as: GB2385718B; GB0204492D0

Abstract

A power base (2) for an electrical appliance having an upper surface (8) for receiving the appliance, and an electrical connector (10) for making electrical connection with the appliance. Support means (26) are provided which, in a first position, support the appliance away from the upper surface (8) of the base (2) so that electrical connection is not made between the connector on the base (10) and the appliance. The support means (26) has a second position which allows the appliance to rest on the upper surface (8) of the base (2) so that an electrical connection is made between the connector (10) on the base and the appliance. Manual means are provided for moving the support means (26) from the first position to the second position. The support means (26) are automatically returned from the second position to the first position when the appliance is removed from the base (2).

Description

Liquid Heating Appliances The present invention relates to cordless electrical appliances or more particularly to cordless electric liquid heating appliances.

A cordless liquid heating appliance generally comprises a liquid heating vessel which, in use, is placed on a free-standing base unit connected to a power supply. When the vessel is positioned on the base, connection is made between the respective electric terminals of the base unit and the vessel, and a heater associated with the vessel may be energised. In general, some form of manual intervention will first be required to switch the appliance on, before power is supplied to the heater.

Power will normally continue to be supplied to the vessel heater until a control operates to disconnect the power supply to the heater. Such a control may, for example, comprise a steam sensitive control which interrupts the power supply to the heater once the liquid boils, or a thermostatic control which operates at some predetermined liquid temperature.

After the control has operated in this way, it is often desirable to be able to maintain the heated liquid at or around a given temperature. For example, in some contexts it is useful to be able to maintain the liquid at its boiling point e. g. to sterilise a liquid. In other applications it is desirable to maintain a liquid at a predetermined temperature below its boiling point.

In particular, if the appliance is an infusion beverage maker, e. g. a coffee maker, it is advantageous to be able to keep the infused beverage warm.

The heated liquid may be maintained at a desired temperature after operation of the control in a number of ways. For example, the main heater may remain

energised but at a lower power level, or it may be operated intermittently. Alternatively, a separate lower powered heater may be provided specifically for this purpose. Such a heater may initially be energised with the main heater and remain so once the control has operated, or may be switched on only after the power supply to the main heater is disconnected. This type of arrangement is particularly suitable if the heater is a thick film heater, when a separate appropriately powered "keep warm"track is commonly provided. Although power to the main heater is generally disconnected on operation of the control, the keep warm heating means will frequently remain energised for a considerable time, often as long as power is supplied to the vessel.

A potential problem involved in incorporating a "keep warm"facility in a cordless electric liquid heating appliance is that, in general, the keep warm heating means will continue to be energised until a user intervenes to manually switch the appliance off. In a cordless appliance, once the keep warm heating means has been energised, it will, in the absence of any intervention to specifically disconnect its power supply, remain so at all times when the vessel is positioned on the base. Thus if the vessel is removed from the base, e. g. to pour out some of the liquid, the power supply to the keep warm heater will automatically be resumed as soon as the vessel is replaced, even if there is no liquid left in the vessel.

This may eventually lead to the heater of the vessel overheating and the operation of an overheat protection control. At the very least, it will be wasteful of energy. Neither of these possibilities is desirable.

The present invention seeks to provide a solution to this problem. The Applicants have recognised that suitable means may be incorporated in the power base of a cordless electrical appliance which allows electrical

connection to be made to an appliance positioned on it only upon manual intervention of the user, even when the appliance is replaced on the base after being removed for a period of time.

Thus, according to a first aspect of the invention there is provided a power base for an electrical appliance said base comprising: an upper surface for receiving the appliance; an electrical connector for making electrical connection with the appliance; support means which in a first position support the appliance away from the upper surface of the base such that an electrical connection is not made between the electrical connector on the base and the appliance, and which in a second position allows the appliance to rest on the upper surface of the base such that an electrical connection is made between the base connector and the appliance; means for manually moving said support means from the first position to the second position; and means for returning said support means automatically from the second position to the first position when the appliance is removed from the base.

Thus in accordance with the present invention, the appliance, preferably a liquid heating appliance, is prevented from moving into electrical connection with the base until a user manually intervenes to move the control member from its first to its second position.

If the appliance is subsequently lifted from the base, the support means will automatically revert to its first position, so that when the appliance is subsequently replaced on the base, manual intervention is once more required to move the control member to its second position to reestablish the electrical connection between the base and the appliance.

Thus in the case of a liquid heating appliance, the default state of the base is such that power is not supplied to the heating vessel, and even if a keep warm heating means was energised when the vessel was lifted

from the base, power will not be reconnected to it until the user manually moves the control member.

The support means preferably comprises one or more support members which extend through the support surface, and in the preferred embodiment, the support means comprises a plurality of pins or rods extending through the support surface. Most preferably the pins or rods are equispaced circumferentially of the support surface.

The support member or members is/are preferably supported on a control member, the position of which determines the position of the support members.

The control member could comprise say a rotary cam arrangement with the axis of rotation generally parallel to the surface of the base. Preferably, however, it comprises a translatable, for example a slidable, member. Although the control member could be linearly movable, it is preferably rotatably movable. Thus in the preferred embodiment, the control member may comprise a movable ring.

The control member is preferably provided with a knob for manipulation by a user when it is desired to move the support means into its second position.

Preferably the control member is biased towards the first position by spring means, so as to effect the automatic movement of the control member to the first position.

The control member may comprise a cam surface for supporting the support members such that as it moves from its first position to its second position, the support members drop, allowing the appliance to engage the support surface of the base. The control member may be biased towards its first position by spring means, such that when the appliance is lifted from the base, the control member moves to lift the support members.

In such an arrangement the cam should be configured such that the support members cannot drop again until the

control member is moved manually into its second position. Also the weight of the appliance on the support members and the friction arising between the support members and the cam surface should be sufficient to overcome the biasing force of the spring.

However, in a particularly preferred embodiment the control member is provided with one or more slots for receiving the support members. The support member is preferably provided with a collar which can engage over the upper surface of the slot in the first position, so as to support the appliance. The slot is also provided with an enlarged portion into which the collar may move in the second position of the control member, so allowing the appliance to drop onto the base surface.

Preferably the support members are biased upwardly through the slots. Again in this embodiment, the control member may be biased towards the first position by spring means.

It should be appreciated that in its broadest aspects, the present invention also extends to a cordless electrical appliance comprising an appliance and a power base therefor, the power base having an upper surface for receiving the appliance thereon in electrical connection thereto, and wherein after removing the appliance from electrical connection with the base, on replacing the appliance on the base, electrical connection between the base and the appliance may only be resumed after manual intervention by a user.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a view showing a power base unit of the present invention with the slider ring in a first position; Figure 2 is view of a power base of the present invention with the slider ring in a second position; Figure 3 is a cross-sectional view along the line

III-III of Figure 1; and Figure 4 is a cross-sectional view along the line IV-IV of Figure 2.

With reference to the Figures, a power base 2 is connected to a source of electrical power through a lead (not shown). The base 2 comprises a main moulded body 4 with cover moulding 6 providing an upper surface 8 for receiving a water heating vessel such as a kettle (not shown.

An electrical connector 10 projects from the upper surface 8 for engagement with a mating connector of the kettle. The skilled person will recognise the connector 10 as one of the Applicant's P72 connectors, which allow electrical connection to be made between a base and vessel irrespective of their relative rotational orientation.

A control member in the form of a ring 12 is slidably and rotatably mounted in a channel 14 provided in the base body 4. The ring 12 has a knob 16 which projects through an aperture 18 in the moulding 4.

The ring 12 is provided with three keyhole shaped slots 20 equispaced around the ring 12. Each slot 20 has an elongate portion 22 and an enlarged head 24.

Three pins 26 extend up through the slots 20. The pins 26 are hollow and are mounted over spigots 28 provided in wells 30 in the base moulding 4. The pins 26 each have a collar 32, and a coil spring 34 extends between the collar 32 and the bottom of the well 30, so as to bias the pins 26 upwardly. The pins 26 are limited in their upward movement by the base cover 6.

As can be seen from Figures 1 and 3, when a pin 26 is raised, the collar 32 extends over the edge of the elongate slot portion 20. When it is lowered, the collar engages within the enlarged slot head 24.

A torsion spring 36 mounted on a spigot 38 in the moulding 4 extends between a mounting 40 on the ring 12 and the moulding 4 so as to bias the ring 12 in the

clockwise direction towards the position shown in Figure 1.

Operation of the power base 2 in accordance with the present invention will now be described. At all times when the liquid heating vessel is not in place on the base 2, the ring 12 will be urged by the spring 36 to the position shown in Figure 1. In this position, as mentioned above, the pin collars 32 will overlap the edges of the elongate slot portion 20, so that the pins 26 cannot be pressed down.

Accordingly if a heating vessel is then placed on the base 2, the pins 26 will remain in this raised position, maintaining the vessel above the surface 8 of the base and preventing an electrical connection from being made between the base connector 10 and the vessel connector. Preferably the pins 26 are sized so as to result in the vessel being raised around 3-4mm above the upper surface 8 of the base 2.

If the user then moves the knob 14 anti-clockwise towards the position shown in Figure 2, against the force of the spring 36, the collars 32 of the pins will align with the enlarged slot heads 24 such that the pins will be forced downwardly by the weight of the vessel against the force of the coil springs 34 into their lower position as shown in Figures 2 and 4. This allows the vessel to move towards the base 2, such that electrical connection is made with the connector 10, whereby power is supplied to the vessel heater, and liquid in the vessel heated.

When the vessel is removed from the base 2, say after liquid in the vessel has boiled, the coil springs 34 will push the pins 26 upwardly towards their raised position, thereby disengaging the collar 32 from the enlarged slot head 24. The torsion spring 36 will then act to return the ring 12 to the position shown in Figure 1, so that the pins 26 are once more retained in their raised position. Accordingly, when the vessel is

replaced on the base 4, it will be maintained out of electrical connection with the connector 10 by the raised pins 26 and the ring 12 must then be moved by the user to the position of Figure 2 to make that electrical connection.

It will be appreciated that various modifications may be made to the above described embodiment without departing from the scope of the invention. For example, a different number of pins may be provided, or the pins may be movable by a cam mechanism.

Also, while the invention is primarily for use with vessels having secondary heating means, such as a keep warm heater, it can be used with other vessels as well.

Indeed the invention may be applied to all manner of cordless electrical appliances, not just liquid heating appliances.

Claims

Claims: 1. A power base for an electrical appliance said base comprising: an upper surface for receiving the appliance; an electrical connector for making electrical connection with the appliance; support means which in a first position supports the appliance away from the upper surface of the base such that an electrical connection is not made between the electrical connector on the base and the appliance, and which in a second position allows the appliance to rest on the upper surface of the base such that an electrical connection is made between the base connector and the appliance; means for manually moving said support means from the first position to the second position; and means for returning said support means automatically from the second position to the first position when the appliance is removed from the base.
2. The power base of claim 1 wherein the support means comprises one or more support members which extend through the support surface.
3. The power base of claim 2 wherein the support means comprises a plurality of pins or rods extending through the support surface.
4. The power base of claim 3 wherein the pins or rods are equispaced circumferentially of the support surface.
5. The power base of any of claims 2 to 4 wherein the support member or members is/are supported on a control member, the position of which control member determines the position of the support member (s).
6. The power base of claim 5 wherein said control member comprises a translatable member.

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7. The power base of claim 5 or claim 6 wherein said control member is rotatably movable.
8. The power base of any of claims 5 to 7 wherein the control member comprises a movable ring.
9. The power base of any of claims 5 to 8 wherein the control member is provided with a knob for manipulation by a user when it is desired to move the support means into its second position.
10. The power base of any of claims 5 to 9 wherein the control member is biased towards the first position by spring means.
11. The power base of any of claims 5 to 10 wherein the control member comprises a cam surface.
12. The power base of any of claims 5 to 11 wherein the control member is provided with one or more slots for receiving the support member (s).
13. The power base of claim 12 wherein the or each support member is provided with a collar which can engage over the upper surface of the slot (s) of the control member in the first position, so as to support the appliance, the slot (s) also being provided with an enlarged portion into which the collar (s) may move in the second position of the control member, so allowing the appliance to drop onto the base surface.
14. The power base of claim 12 or 13 wherein the support member (s) are biased upwardly through the slot (s).
15. The power base of any preceding claim wherein the power base is for a liquid heating appliance.

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16. A cordless electrical appliance comprising an appliance and a power base therefore, the power base having an upper surface for receiving the appliance thereon in electrical connection thereto, and wherein after removing the appliance from electrical connection with the base, on replacing the appliance on the base, electrical connection between the base and the appliance may only be resumed after manual intervention by a user.
17. A power base as hereinbefore described with reference to the accompanying drawings.
18. A cordless electrical appliance as hereinbefore described with reference to the accompanying drawings.