GB2361815A

GB2361815A - Cordless electrical appliance having connector with retractable pins

Info

Publication number: GB2361815A
Application number: GB0010213A
Authority: GB
Inventors: Robert Andrew O'neill; John Anthony Howarth
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 2000-04-26
Filing date: 2000-04-26
Publication date: 2001-10-31
Anticipated expiration: 2020-04-26
Also published as: GB2361815B; GB0010213D0; WO2001080699A1; AU5054201A

Abstract

A cordless electrical appliance, such as a kettle, has a base unit with terminals 15 arranged under a planar surface, and has retractable connector pins 5. A manual ON/OFF lever 8 moves a body 4, which operates switch 3 and projects the pins 5. Parts 12 and 13 ensure that this only happens which the kettle is on its base. A steam sensor 9 and boil dry sensor 10 can also switch the kettle off. Terminals 15 may be rings, to allow the kettle to be placed in any orientation.

Description

2361815 1 IMPROVEMENTS RELATING TO CORDLESS ELECTRICAL APPLIANCES

Field of the Invention:

This invention concerns improvements relating to cordless (as opposed to corded) appliances wherein electricity is provided to the appliance proper through a corded base unit upon which the appliance proper may be removably seated so as to cause complementary electrical connectors that are provided in the appliance proper and in the base unit to interengage for supplying electricity through the base unit to the appliance proper. In the following, the invention will be described by reference to cordless liquid heating appliances, particularly though not exclusively water heating appliances such as kettles and hot water jugs for example, but it is to be understood that the invention has wider application.

Background of the Invention:

Cordless electric kettles and hot water jugs are well known in which the connector that is provided on the base unit projects upwardly from the surface of the base unit for engagement with a recessed connector in the underside of the appliance proper. The 3600 cordless connector system which we manufacture and sell as our CS4/CP7 system is of this kind, as is the similar system that is manufactured and sold by Strix Ltd. The CS4/CP7 system is substantially as described in GB-C-2 285 716 and the Strix system is substantially as described in WO-A-9508204.

The connector projecting from the appliance base unit has been considered to be less than aesthetically pleasing and in our British Patent Application No. 9912444.8 we have made proposals for a flat cordless connection system. The principal problem with a flat cordless connection system is that of guiding the appliance proper so that it mates correctly with its base unit, so that the electrical connections are smoothly guided into engagement. In the past, with fixed connector pins provided on the appliance, it has as abovementioned always been necessary to have a raised area on the base unit which projects into a recess in the bottom of the appliance. This allows the electrical contacts of the base, which are live and thus have to be insulated from possible contact with users, to reach the corresponding electrical contacts of the appliance, which have to be located above the bottom of the appliance so that they do not prevent the appliance sitting on a flat surface. It has been usual in the past to use this raised area as a guide to ensure smooth engagement of the appliance with its base. With a "fiaf' cordless base there is no such convenient guide, so, in addition to providing 3 the actual electrical connections, it is necessary to provide additional guidance features.

Objects and Sunungly of the Invention:

It is the object of the present invention to overcome or at least substantially reduce the abovementioned problem.

According to the present invention, in one of its aspects, in order to overcome the electrical connection problem and allow the base unit contacts to be below the top surface of the base and still be able to make connection with the contacts of the appliance, we propose to make the appliance contacts vertically movable so that they may be extended below the base of the appliance once the appliance is correctly positioned on its base, but are held within the appliance body at all other times.

Described in detail hereinafter is an exemplary embodiment of the invention in which the base unit has a completely planar surface, except for the provision of means guiding the appliance proper into proper registry with the base as it is seated down upon the base. The base unit connector is provided beneath the upper surface of the base unit and has its electrical terminal parts in appropriate registry with apertures provided in the base unit upper surface for enabling terminals of the appliance connector to access the base unit connector. The appliance proper likewise has a completely planar 4 under surface, except for the provision of complementary guidance means, and apertures are provided in such surface to enable the appliance connector terminals to be extended through its under surface for making electrical connection with the base unit connector. The appliance connector terminals are mounted within the bottom of the appliance proper on a vertically movable part which, as described hereinafter, can be moved manually by operation of an ON/OFF control of the appliance and, furthermore, is movable through operation of an automatic boiling control of the appliance and/or through operation of a heating element overtemperature protection device of the appliance. An interlock can also be provided to inhibit movement of said part if the appliance proper is not seated on its base and/or to withdraw said part automatically so as to retract the tenninals of the appliance proper if the appliance proper should be lifted while still switched on.

We are aware of GB-A-2 185 158 which discloses the provision in the handle of a cordless hot water jug of a trigger which, when operated, causes terminal pins of the appliance connector part to withdraw, horizontally, from the base connector thereby allowing the jug to be lifted. This arrangement suffered the disadvantage that the base unit could be lifted with the jug if the trigger was not correctly operated. As will be seen from the following description the present invention enables this disadvantage to be overcome without conscious action by a user.

The above and further features of the present invention are set forth in the appended claims and will become clear from consideration of the following detailed description of the abovementioned exemplary embodiment which is illustrated in the accompanying drawings.

Description of the Drawings:

Figure 1 is a schematic illustration of an exemplary cordless appliance embodying the present invention and shown with the appliance proper lifted off its base unit; Figure 2 is a schematic illustration showing the embodiment of Figure 1 with the appliance proper seated on its base unit; Figure 3 shows isometric views of the appliance bottom and of the upper surface of the base unit for the embodiment of Figures 1 and 2; and Figure 4 is a sectional isometric view illustrating the use of a 360' connector in the base unit of the embodiment.

Detailed Description of the Embodiment:

The accompanying drawings show a liquid heating appliance having a thick film printed heating element, but in principle any type of heating element could be used, including both conventional sheathed immersion 6 heaters and sheathed heating elements secured to the underside of a metal plate forming or affixed to the bottom of the liquid containing vessel of the appliance. The system described could also be applied to any type of appliance for which a cordless connection system is appropriate and the invention is not limited to liquid heating appliances.

Under the heating element there is provided a chassis upon which the other components are mounted. For clarity the accompanying drawings do not show the chassis, and the components which are supported from it are shown in free space. From the chassis there are resilient connections (1) which make contact with the heating element (2) and, at their other ends, have contact locations (3) for making connection with a movable part (4) which carries the connector pins (5). Alternatively connection may be made by flexible wires, welded or otherwise secured to the element connection points and to the pins of the movable part. The movable part 4 is constrained to move in a vertical direction, though with a small amount of lateral compliance, and the connector pins (5) which project from its lower face have, on their upper ends, contact areas (6) which, when the movable part is moved downwards, make contact with the resilient element connections (3).

The movable part (4) is arranged to be driven by a resilient lever or cantilever (7) which is arranged to be moved by an overcentre mechanism (8).

The overcentre mechanism has a number of means of actuation. It may be moved by hand in the act of switching the appliance on or off, it may be 7 moved by a schematically shown actuator (9) sensitive to the liquid in the appliance boiling, for example a bimetal, and it may be moved by a schematically shown dry boil sensitive actuator (10) which acts to protect the heating element against overheating. The manual action can move the part 4 to the "on" position, and all three means can move it to the "off' position.

Between the overcentre mechanism (8) and the resilient]ever (7) there is a joint (11) having lost motion, and a lever or pin (12) is provided which acts as a key to take up the lost motion, so that, when the key is inserted, the movement of the overcentre mechanism (8) is transmitted to the resilient lever (7). The key (12) is engaged by placing the appliance correctly on its base.

This act depresses a pin (13) which extends from the bottom of the appliance and which is pushed upwards as the appliance proper is positioned on its base.

The appliance proper may have feet (19) projecting from its bottom, and the pin (13) does not extend beyond these, so as not to be operated by placing the appliance on a flat surface. However, when the appliance is position on its base, the feet (19) locate in depressions (18), so that the pin (13) can contact the raised surface of the base. Alternatively a projection may be positioned on the top surface of the base to engage the pin. A linkage (14) within the base transforms the vertical motion of the pin (13) into the movement necessary to engage the key (12) with the overcentre mechanism (8), both against the action of respective return springs (not shown).

8 In operation, the appliance is positioned on its base and the key (12) is engaged with the joint (11) by the action of the pin (13) so as to lock the overcentre mechanism (8) into engagement with the resilient lever (7). The resilient lever (7), which is normally biased upwards so as to retract the part (4) carrying the connector pins (5), may now be pushed downwards by operation of the ON/OFF mechanism (8), thereby extending the pins (5) below the bottom of the appliance, to engage. the base contacts, which are described below. As the connector pins (5) move downwards, the contact areas (6) on their upper ends first come into contact with the resilient element connections (3) and then the pins (5) make contact with the contacts of the base unit. Normally there are three pins (L, N & E), and these are arranged to form a triangle (le. they are not co-linear) so that as contact is made, the movable part (4) has some compliance in its orientation and can adjust so that all three pins make good contact. This allows the base contacts to be of a simple rigid construction. Once electrical contact is established, any further movement of the overcentre mechanism (8) to its stable end position is accommodated by flexing of the resilient lever (7). The overcentre mechanism, in this end position, is arranged to be sufficiently over centre to be stable and to hold the various contacts together, but to be relatively lightly biased so as to allow the various birnetal actuators (9), (10) to have sufficient energy to trip it to return it to its initial OFF position. Similarly, lifting of the appliance proper from its base while the appliance proper is still switched on 9 will cause the pin (13) to reset and this can be arranged to cause the lever (7) to reset thus retracting the part (4) and the pins (5).

Because contact resilIence is provided in the movable contact assembly in the appliance proper, the contacts in the base unit can be simple and rigidly mounted. The tolerance in height over which connection will be made is not dependent on any sliding or flexing within the base, as with presently available systems, and thus the height requirement of the base contacts can be much reduced. The form of the base contacts will depend on the type of cordless system utilized, with simple single point contacts being all that is required for a conventionally aligned arrangement, namely an arrangement where the appliance proper has to be seated on its base unit with the two parts in a particular mutual alignment. For a preferred 360' cordless connector system, which is the system shown, annular contacts will be needed. Since the moving pins of the appliance proper are simple in form and can be made of relatively small cross section, since they are protected within the body of the appliance, thus the apertures in the base unit through which the appliance pins access the base unit can be made small and/or narrow, so that they are inherently safe. Apertures with a width of less than 3mrn with a flared upper opening for guidance could be used, so that a protective shutter is unnecessary from a safety viewpoint. However connectors with shutters are preferred, since they discourage the ingress of contamination, for example during cleaning, so a shutter could additionally be provided. A simple form of shutter is described below. The base contacts themselves (15) are positioned below the apertures, and spaced from them by a distance determined by the safety requirements for the appliance for which they are intended (8mm normally is adequate). In order to minimise the height of the connector the base contacts as illustrated are co-planar, but they could be placed on different levels to give sufficient clearance between themselves in a more reduced area.

That is, if the contacts require 3mrn separation, then this could be made up of a vertical as well as a horizontal component, and the diameter of the resultant connector could thereby be reduced. As shown, the earth contact nng (16) is shown raised towards the surface, since it does not require any clearance distance. Internally, the base connector unit may be provided with the necessary drainage and water shedding features to ensure that the entry of water through the apertures does not cause a hazard.

In the simplest form and as shown in Figure 4 the contacts of a 360' connector in the base unit could be two annular flat slip rings stamped from metal strip, with a central contact plate. A silver contact could be placed on the central plate to withstand the make and break duty arising through operation of the controls (9) and (10) and in manual switching on and off of the appliance. The outer rings could be plated if necessary. To reduce cost, at leas the outermost ring could be formed from a narrow strip rolled into a ring, possibly with a rolled upper edge to give a greater contact area. This would save the material wasted from the centre of a flat pressed ring.

11 To provide some shuttering closure of the contact openings, which would be mainly cosmetic while reducing the ingress of water and other contamination, a simple disc (17) of elastomeric material, such as rubber or neoprene, could be used. Of the two rings of the base connector, the outer would be earth, and would not need to be shielded. The inner ring and central hole (neutral and live respectively) are covered by the clastomeric disc, whose diameter is slightly greater than that of the outer diameter of the inner ring opening. The disc is supported on the underside of the central part of the connector by adhesive, by being pressed over pegs, or, preferably, by being trapped between the components of the base connector during assembly. The centre of the disc has a slit, or it may have two crossed slits, through which the central pin of the appliance connector may pass. The pin corresponding to the inner ring deflects the outer edge of the disc locally at the point where it enters the base connector. These deflections of the elastomer disc (17) are shown in Figure 2.

With the system described above, the need for guidance to ensure easy mating of the appliance proper with its base unit is reduced to the simple necessity of ensuring that the appliance comes to rest in the correct position to align the appliance pins with the apertures in the base. With a conventional (non-360') cordless appliance this will require some assistance to ensure correct orientation, which may require the provision of some feature(s) on the base to engage complementary mating feature(s) on the appliance. For a 360' 12 appliance, however, orientation is not a problem, and it is only necessary to ensure concentricity (or axial alignment) of the appliance proper with its base.

This may be achieved, as shown in the drawings, by provision of an annular groove (18) with sloping sides on the top surface of the base - a truncated triangular cross section - into which the feet of the appliance will naturally slip during the last moments of approach. Alternatively, and as proposed in our British Patent Application No. 9912444.8, the appliance may be provided with a skirt around its periphery which has an inwardly sloping inner surface which engages the outside edge of the base.

A major advantage of the described flat cordless connection system is the lack of projecting pins which have to be guided. There is no tendency for pins to bind in their apertures as with conventional systems which can sometimes pick up the base when lifted. Furthermore, by provision of flared openings leading into the base apertures as mentioned above, it can be ensured that the appliance pins smoothly enter the base apertures on switching on with any slight misalignment being corrected automatically.

The cordless connection system described above can be used equally with conventional (non-360') and 360' appliances. In fact the same appliance pins (and even the same appliance) may be used with either type of base, without the inefficiency of simply restricting the rotation of an expensive 360' connector. As far as we are aware this is the first time such flexibility has been possible.

13 Having described the invention in the foregoing by reference to a specific embodiment, it is to be appreciated that the embodiment is in all respects exemplary and that modifications and variations are possible without departure from the spirit and scope of the appended claims. For example, in an alternative construction, the overcentre mechanism may be a simple lever, spnng loaded into the "off' position. A latch may hold the lever in the "on" position, and the boil or dry boil bimetals may act to release the latch. A manual method of releasing the latch may also be provided so that the appliance can be switched off by hand.

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Claims

CLAIMS:

1. A cordless electrical appliance comprising an appliance proper, a base unit and co-operating electrical connectors on the appliance proper and on the base unit which are adapted to interengage when the appliance proper is seated on its base unit, the base unit connector being accessible through openings provided in an upper surface of the. base unit and the appliance proper connector having retractable terminals which can be advanced through openings in a bottom surface of the appliance proper for accessing the base unit connector via said base unit openings.

2. A cordless electrical appliance as claimed in claim 1 wherein a manually operable control is provided on the appliance proper for enabling it to be switched ON and OFF by advancing and retracting said terminals.

3. A cordless electrical appliance as claimed in claim 2 wherein an interlock is provided in the appliance proper to inhibit switching ON of the appliance if it is not seated on its base unit.

4. A cordless electrical appliance as claimed in claim 3 wherein the manually operable control forms part of an overcentre mechanism provided with lost motion, and said interlock is arranged to negate said lost motion when the appliance is seated on its base unit.

5. A cordless electrical appliance as claimed in any of the preceding claims wherein the terminals of the appliance proper are mounted so as to be compliant for accommodating differences in the orientation of the appliance proper and base unit connectors.

6. A cordless electrical appliance as claimed in claim 5 wherein the base unit connector has fixedly positioned terminal parts, and the appliance proper connector has its terminals connected to a part which not only is movable in a predetermined direction for advancing and retracting the terminals, but also has a degree of freedom to move in other directions to provide said compliance.

7. A cordless electrical appliance as claimed in any of the preceding claims wherein the base unit connector is a 360' connector, the openings provided in the upper surface of the base unit providing for access of the appliance proper terminals to the base unit connector throughout 360' of relative rotational orientation between the appliance proper and the base unit.

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8. A cordless electrical appliance as claimed in any of the preceding claims wherein the appliance is a liquid heating appliance and the terminals of the appliance proper are arranged to be retracted by operation of one or more thermally-responsive controls in the appliance proper.

9. A cordless electrical appliance as claimed in claim 8 wherein said thermally-responsive control comprises a heating element overtemperature protection control.

10. A cordless electrical appliance as claimed in claim 8 or 9 wherein said therTnallyresponsive control comprises a control for switching off the appliance when liquid is heated to a predetermined temperature (eg. boiling) therein. 15

11. A cordless electrical appliance as claimed in any of claims 8, 9 and 10 wherein the appliance proper has a thick film heating element.

12. A cordless electrical appliance as claimed in any of claims 8 to 11 wherein electrical connections in the appliance proper between the heating 20 element and the appliance proper connector are arranged to be broken when the terminals of the appliance proper connector are retracted and made when said terminals are advanced.

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13. A cordless electrical liquid heating appliance substantially as herein described with reference to the accompanying drawings.

14. A cordless electrical liquid heating appliance having a retractable connector associated with the appliance proper, there being provision for manually advancing the retractable connector when the appliance proper is seated on its base unit so as to interconnect the appliance proper and base unit connectors, and means being provided for automatically retracting the 10 advanced connector when liquid is heated to a predetermined temperature (eg. boiling) in the appliance proper.