ELECTRICAL CONNECTION CONTACTS

The present invention relates to electrical terminals and in particular to electrical terminals for cordless electrical appliances such as kettles and hot water jugs.

In traditional corded appliances, a power socket connected to a power supply is pushed onto the terminal pins of an appliance. The terminal pins are traditionally made from brass. In cordless appliances, an appliance is placed down on a power supply base connected to a power supply and in so doing, terminal pins in the appliance makes electrical contact with contacts provided in an electrical connector provided on the base. It has been found that in such applications brass terminal pins are susceptible to wear and degradation due to arcing which occurs as the terminal pin is brought into engagement with the corresponding base contact.

The present invention seeks to overcome the above problem. From a first aspect, therefore, the present invention provides a terminal pin for a cordless electrical appliance, said pin having an elongated contact surface, said contact surface being provided by a metallic material which does not contain zinc.

The material may be a precious metal such as gold, silver or alloys thereof, or other metals such as copper tin, nickel or iron or alloys thereof.

In one embodiment, the contact surface may be formed by a layer of plating which is applied to the pin.

In another embodiment, the elongate contact surface may be formed by a separate elongate member which is suitably attached to the pin.

The member may be attached to an external planar surface of the pin or be laid into a slot, recess or groove in the pin surface.

The member may be welded, for example electron beam or laser welded, to the pin or pressed onto the pin.

The member may be in the form of a strip of material, a cap which clips over the pin or a sleeve of material which is arranged around the pin. Again the cap or sleeve may be attached by any of the processes described above.

Preferably the member is greater than 0.2 mm, more preferably greater than 0.3 mm in thickness to provide the requisite strength and erosion resistance.

Preferably the contact surface extends for at least 10 mm along the pin.

As has been stated above, the contact material may be a precious metal such as silver or gold. Silver is particularly useful for this purpose and alloys thereof may also be used. Typically the alloy may comprise substantially silver, but with alloy additions of for example nickel, cadmium or tin.

The pin itself can be made of any material, for example brass or iron.

It may also be feasible to make the whole pin from a non-zinc metal so from a further aspect the invention provides a terminal pin for a cordless electrical appliance said terminal pin being formed of non-zinc containing metal or metal alloy.

The pin may be of a precious metal such as silver or a silver alloy. It could also be iron, copper, tin, nickel or alloys thereof.

The pins described above are particularly for use in a cordless electrical connectors. The pins may be mounted in any suitable manner on the appliance, but preferably that form a part of as thermally sensitive control of the appliance, such as one of the Applicant's R7 series of controls.

The invention also extends to a cordless electrical connector set comprising an appliance connector part comprising a pin in accordance with the invention and power base connector part comprising a contact for making contact with the pin.

The power base contact may be mounted on or provided by a leaf spring of for example copper, iron or alloys thereof. For example, the contact may be a copper backed silver, silver alloy, tin, tin alloy, nickel or nickel alloy contact. A solid silver, silver alloy, tin, tin alloy, nickel, nickel alloy, copper or copper alloy contact could also be used. Typically these contacts will be rivetted into position on the leaf spring.

Alternatively the leaf spring may have a silver, copper, tin, nickel (or alloys thereof) onlay laminated to its surface. Typically these materials are supplied in the form of a wire or tape which can be welded or otherwise attached to the pin.

The contact surface may also be formed by plating a material as above onto the leaf spring.

In an alternative embodiment, a contact as described above may be mounted on a coil spring.

Preferably the power base contact is arranged to wipe along the contact surface as the appliance is placed on the power base.

Some embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

1. Figure 1 shows a cordless electrical kettle;
2. Figure 2 shows the arrangement of the terminal pins of the kettle of Figure 1;
3. Figure 3 shows a side view of one of the pins of Figure 2;
4. Figure 4 shows the engagement of the pins of the kettle with the power base connector;
5. Figures 5A to 5D show various terminal pins constructed in accordance with the invention; and
6. Figures 6A to 6E show various base contacts constructed in accordance with the invention.

With reference to Figure 1, a cordless electrical kettle 2 comprises a kettle body 4 which rests on a power base 6. A cordless power connector 8 extends upwardly from the surface of the power base 6 and receives terminal pins 10 of the kettle 4. A power lead 12 is connected to the connector 8, the lead 12 having a plug 14 which can be inserted into a wall socket.

As shown in Figure 2, the terminal pins 10 of the kettle 4 comprise live and neutral pins 10a, 10b and an earth terminal 10c. The terminal pins 10 may form an integral part of a thermally sensitive control unit 16 for the kettle, as is known in the art. For example, the control unit may be one of the Applicant's R7 series of controls.

As shown in Figure 4, the live and neutral terminal pins 10a, 10b engage with respective leaf spring mounted contacts 18 housed within the electrical connector 8, which in this instance one of the Applicant's commercially available P69 connectors (only one pin is shown for clarity, but both engage in the same manner). The pins 10a, 10b 10c are introduced through slots 20 provided in the top of the connector 8, the slots 20 being closed in normal use by a spring loaded shutter 22 which is pushed out of the way by the earth pin 10c as the kettle 4 is placed down on the power base 6. The earth terminal 10c engages an earthed leaf spring (not shown) when inserted into the connector 8.

As can be further seen in Figure 4, as the kettle 4 and control unit 16 is placed downwardly over the connector 8 the contact 18a moves from the dotted position to the solid position i.e. it moves along a longitudinal portion of the terminal pins 10a, 10b so that it in effect wipes along the terminal pins 10a, 10b.

Turning now to Figure 5A to 5D, various terminal pin constructions are shown.

In Figure 5A, the pin 30 is just a solid pin of a non-zinc containing metal, such as silver, iron, copper, tin, nickel or alloys thereof.

In Figure 5B, the pin 32 comprises a main body 34 which may also be of materials as discussed above or even brass and a contact area 36 formed by an inlay, onlay, throughlay or edgelay of an electrically more conductive material, for example silver, copper, tin, nickel or alloys thereof. The inlay etc material 36 may be welded, for example laser welded or electron beam welded, or otherwise attached to the main body 34 of the pin. The contact area 36 is downwardly facing, and may extend over the entire length of the pin 10a, 10b or just over a limited longitudinal extent, as shown, sufficient to encompass the range of movement of the connector contact 18.

In Figure 5C, the pin 38 comprises a main body 40 of a material as discussed above and a cap or sleeve 42 fitted onto the body 40 to form a contact surface. Again the cap or sleeve 42 is preferably of an electrically more conductive material than the main body 40 such as silver, copper, tin, nickel or alloys thereof.

Typically the cap or sleeve 42 is greater than 0.3 mm in thickness to give the required strength. The cap or sleeve 42 is attachable to the pin by any suitable method, for example welding as discussed above. The advantage of the arrangement of this arrangement is that irrespective of which way the pin 10 is mounted in a control unit or other connector body one surface of the pin will always have a contact forming region.

In Figure 5D, the pin 44 comprises a main body 46 of a material as discussed above and a plated layer 48 preferably of an electrically more conductive material than the main body 46 such as silver, copper, tin, nickel or alloys thereof.

Turning now to Figures 6A to 6E, there are shown various contact member constructions suitable for use with the pins of Figure 5.

The contact member 50 of Figure 6A comprises a leaf spring 52 typically of a copper or iron alloy having a contact 54 rivetted onto it. The contact 54 comprises a copper backing 56 and a facing of silver, tin, nickel or alloys thereof.

The contact member 60 of Figure 6B comprises a leaf spring 62 again typically of a copper or iron alloy having a contact 54 rivetted onto it. The contact 54 in this embodiment is of a solid silver, tin, nickel or alloys thereof and is rivetted to the leaf spring 62.

The contact member 70 of Figure 6C comprises a leaf spring 72 again typically of a copper or iron alloy having a plated contact surface 74. The contact surface is of silver, tin, nickel or alloys thereof.

The contact member 80 of Figure 6D comprises a leaf spring 82 again typically of a copper or iron alloy having a contact 84 attached to it. The contact 84 is of silver, tin, nickel or alloys thereof and typically is applied to the leaf spring 82 in the form of a tape or wire.

All the above contact members 50, 60, 70, 80 are leaf spring arrangements such as shown in Figure 4. In the arrangement of Figure 6E, however, a contact member 90 comprises a coil spring 92 for example of copper, iron or alloys thereof, which mounts a contact 94. The contact 94 can be of the type shown in Figures 6A and 6B, for example, i.e. solid or copper backed contacts.

The various pins of Figures 5A to 5D can be used with any of the pins of Figures 6A to 6E.