GB2153592A - Electrical switches - Google Patents

Abstract

A rocker switch for use in an electrical distribution system comprises an actuator 1 which pivots a movable contact 5 on a fulcrum 6 between an open position, Figure 1 and a &cirf& closed position (Figure 3 not shown) in which contact 5 engages a fixed contact 9, the fulcrum 6 being provided at an intermediate point of an elongate supply conductor 7. The actuator may have an insulating nose 11 which is located between contacts 5 and 9 when the switch is open. In an alternative embodiment, Figure 7, the fulcrum is constituted by the end of a conductor 10 and the fixed contact 62 is provided at an intermediate point of the supply conductor 7. The movable contact 60 is formed with locating means 67, 64 for engagement with the actuator member 101 at off-, mid- and on-positions of the switch. <IMAGE>

Description

SPECIFICATION Electrical switches The present invention relates to electrical switches and more particularly to a switches having an actuator in the form of a rocker member.

In existing switch assemblies a plurality of components is assembled in an insulating housing.

Conductive terminals protrude from the walls of the housing and their exposed ends require some feature permitting mechanical and electrical connection to an electricity supply. Generally this feature is in the form of a tubular part with a clamping screw into which the prepared end of a supply conductor can be inserted and securely retained, or one half of a male/female connector (the other half being attached to the prepared end of a supply conductor), or any other form permitting permanent mechanical connection between the switch assembly and the electrical supply.

The present invention seeks to provide a switch assembly which requires fewer components than existing switches.

According to a first aspect of the present invention, there is provided a switch assembly comprising a rocking actuator member, a movable conductive contact member, a fixed contact member and a conductive fulcrum portion, the movable contact member being pivotable by the actuator member about the fulcrum portion between a first position, in which the movable contact member interconnects the fixed contact member and the fulcrum portion, and a second position in which the movable contact member is disconnected from the fixed contact member, the switch assembly further comprising an elongate supply conductor, said fixed contact member or said conductive fulcrum portion being provided at an intermediate point along the length of said elongate supply conductor.

In such an arrangement the need for switch terminals is avoided.

The present invention also seeks to provide a switch assembly which provides a mechanical indication of switch failure.

According to a second aspect of the present invention, there is provided a switch assembly comprising a rocking actuator member and relatively movable contact members which are selectively engaged and disengaged by rocking of the actuator member, wherein the actuator member has an insulating projection which, in the disengaged position of the contact members, is located therebetween.

Thus is fusing together of the contact members occurs while they are engaged, an attempt to disengage them by rocking of the actuator member results in the insulating projection striking against them, and the resistance to further movement of the actuator member indicates failure of the switch.

The present invention further seeks to provide an improved rocker switch.

According to a third aspect of the present invention, there is provided a rocker switch comprising a rocker actuator member and a movable contact member pivotally mounted at a central region thereof on a conductive fulcrum member, the actuator member engaging a surface of the contact member which comprises a locating recess at said central region and a locating means at each side of the recess, the arrangement being such that the actuator member is located with a first of said locating means in a first pivotal position of the actuator member, with said locating recess in a second pivotal position of the actuator member, and with the other of said locating means in a third pivotal position of the actuator member, The first, second and third positions of said actuator member preferably correspond to off, midand on positions of the rocket switch.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a partly sectional view through a pole of a switch in accordance with a first embodiment of the present invention in an off position; Figure 2 is a side view of the switch of Figure 1 in a mid-position; Figure 3 is a side view of the switch of Figure 1 in an on position; Figure 4 shows a switch which is similar to that shown in Figures 1 to 3 but with slight modifications and which is located in electrical distribution trunking; Figure 5 is a side view through a pole of a switch in accordance with a second embodiment of the present invention in an off position; Figure 6 is a side view of the switch of Figure 5 in a mid-position; Figure 7 is a side view of the switch of Figure 5 in an on position;; Figure 8 is an enlarged view of a fulcrum-forming member of the switch of Figure 5.

Figure 9 is a view on the arrow A of Figure 8; and Figure 10 is a perspective view of the movable contact of the switch of Figure 5.

Referring now to Figures 1 to 4 of the drawings, a switch 20 comprises an insulating rocker 1 having a plunger 2 biassed by means of a plunger spring 3 contained in rocker sleeve 4. The tip 21 of plunger 2 locates in a groove 51 in the surface of a moving contact 5. In the off position of the switch, Figure 1, the contact 5 rests on a fulcrum portion 6 on an electrical supply conductor 7 of rectangular cross-section. The fulcrum portion 6 is formed from, welded to or otherwise affixed to an intermediate point along the length of the conductor 7, with good electrical connection. The normally closed end 52 of contact 5 also rests on the conductor 7 in the off position of the switch.

Pressure applied to the right-hand side of the rocker 1 will cause the rocker to rotate about a pivot point 8, resulting in the plunger 2 compressing the spring 3 as the plunger rises in the sleeve 4 caused by the tip 21 of the plunger moving through an arc and rising on the fulcrum portion 6 as the moving contact 5 moves to the left.

Figure 2 shows the switch assembly at a mid-position. Continued pressure on the right-hand side of the rocker 1 will result in the moving contact 5 passing over the fulcrum portion 6 allowing the contact to 'snap' to the position shown in Figure 3.

In the position shown in Figure 3, the moving contact 5 has moved to the left such that its normally open end 53 abuts a fixed contact 9 located on a component 10 requiring an intermittent electricity supply. The moving contact 5 conducts electricity to the first contact 9 by virtue of making a contact bridge between the fulcrum portion 6 on the electricity supply conductor 7 and the fixed contact 9.

The rocker 1 has an insulating "contact-sensing" leg 11. In the off position of the switch, leg 11 is positioned between contacts 9 and 53. It thus prevents any unintentional making of the circuit by engagement of the contacts caused by an external jolt etc. Figure 3 shows the position of leg 11 in the on position of the switch.

If the switch fails because contacts 9 and 53 weld or fuse together, or because the moving contact 5 fuses to the fulcrum portion 6, any attempt to switch off the switch by depressing the left-hand side of the rocker 1 is resisted by the contact-sensing leg 11 abutting the closed contacts 9 and 53.

The contact-sensing leg 11 is not able to prise apart the closed contacts, and the inability to depress the left-hand side of the rocker 1 is an indication that the switch is not in correct working order.

The above described switch may be employed in a variety of applications, but is especially suitable for use in electrical distribution trunking as shown in Figure 4. The trunking may be such as that described in P.C.T. Patent Application WO 82/03505.

At the right-hand end of Figure 4 the conductor 7 is held between an insulating member 30 within the trunking and the cover member 40 of the switch housing. At the centre of Figure 4, conductor 7 is sandwiched between the insulating member 30 and an insulating terminal carrier member 45. Insulating member 30 and cover member 40 are both preferably of plastics material. Member 30 is secured to the cover member by means of snapping or clipping formations 35. Accordingly there is no need for any direct mechanical linkage between the component parts of the switch 20 and the conductor 7. The pivot point 8 for the rocker 1 is fixed to the cover member 40. A socket for a three pin plug is shown at 42.An advantage of the abovedescribed arrangement is that no soldering is necessary and no terminals are required since the moving contact itself directly engages the supply conductor and the assembly is held together simply by snapping insulating members. Furthermore, the provision of contact-sensing leg 11 is advantageous in that, by indicating failure of the switch, it avoids the need for a separate indicator such as a neon light in or adjacent to the switch. However, the supply of electrical power to conductor 7 may be confirmed by a neon light electrically connected to moving contact 5. Alternatively, the supply of electrical power to component 10, may be confirmed by a neon light electrically connected to fixed contact 9.

Various modifications may be made to the above-described arrangement. For example the normally-closed end 52 of contact 5 may be supported by a container (not shown) for the switch.

Alternatively end 52 may be essentially a mirror image of end 53 and be used to effect a doublethrow switching action. In a further alternative, contact 5 may be mounted in a fulcrum bracket, thereby eliminating the sliding action but still permitting end 52 to rise and fall under the action of rocker 1.

The switch 20 may be a single pole, single throw switch; alternatively it may be constructed as a multipole pole, single throw switch or a multiple pole double throw switch.

The electrical supply conductor 7 may be insulated along its length, with the insulation being removed locally at the fulcrum portion. The fulcrum portion may be formed by a suitable bend in the conductor 7. Conductor 7 may be of rectangular cross-section, as described, or a conventional circular conductor.

Referring now to Figures 5 to 10 of the drawings, there is shown a switch 120 in accordance with a second embodiment of the present invention. An insulating rocker 101 has a plunger 102 biassed by a spring 103 within a rocker sleeve 104. The end face of plunger 102 engages the top surface of a movable conductive contact 60. Contact 60 has a central locating region formed by a portion 64 of triangular cross-section. The top surface of contact 60 has projections 67 which also serve to locate the plunger. The movable contact 60 has a first end 65 which, in the off position of the switch shown in Figure 5, rests on the conductor 10 leading to an electrical socket to be selectively connected in circuit. The other end has a contact surface 61 which is arranged to conductively engage a fixed contact 62 located at an intermediate point of an elongate electrical supply conductor 7.

The contact may be formed entirely from the base material of the conductor, or formed entirely of a precious metal fixed to the conductor. Alternatively it may be a sandwich of precious and base metals.

Raised side regions 64a of portion 64 of movable contact 60 are mounted to pivot on edges 66 of a fulcrum member 68 which is conductively connected to or formed by one end of conductor 10.

Fulcrum member 68 and conductor 10 are insulated from conductor 7 by an insulating member 63.

In use, pressure applied to the left-hand side of the rocker 101 in the off position shown in Figure 5 causes the rocker to rotate about pivot point 8 and plunger 102 moves from its position where it is located against or close to projection 67 at the left to its mid-position shown in Figure 6. In the mid-position, spring 103 is under maximum compression and plunger 102 is aligned with edges 66. As contact 60 rotates clockwise through its mid-position with continued pressure on the left of rocker 101, it snaps into the on position shown in Figure 7, in which plunger 102 is located against or adjacent the projection 67 at the right. In this position contact surface 61 abuts the fixed contact 62 on conductor 7 and the switch is in its on position.

Conductor 7 is secured to the rest of the assembly as described in connection with the arrangement of Figure 4. Other details are also as described in connection with the preceding Figures. The end of conductor 10 remote from the switch forms a socket element 43 arranged to receive the pin of an electrical plug inserted into trunking of which the switch assembly forms part.

As with the first-described embodiment, the above-described arrangement has the advantage that no soldering is necessary and no terminals are required. The arrangement can be held together simply by snapping together plastics housing members. Although it can function only as a single-throw and not as a double-throw switch, the arrangement of Figures 5 to 10 has the advantage that a neon light electrically connected to the moving contact 60 can be used to indicate whether the switch is on or off, since the contact 60 only engages the conductor 7 when the switch is on. The arrangement may be provided with a contact sensing leg 11 as described in connection with the first embodiment.

The electrical supply conductor 7 may be insulated along its length, with the insulation being locally removed at the contact position 62.

As an alternative to edges 66 and regions 64a, the pivot arrangement may be formed by part-circular sections on the contact 60 mounted in arcuate apertures in the fulcrum member 68.

Claims (13)

1. An electrical distribution system comprising at least one elongate supply conductor and a switch, the switch comprising a rocking actuator member, a movable conductive contact member, a fixed contact member and a conductive fulcrum portion, the movable contact member being pivotable by the actuator member about the fulcrum portion between a first position, in which the movable contact member interconnecting the fixed contact member and the fulcrum portion, and a second position in which the movable contact member is disconnected from the fixed contact member, said fixed contact member or said conductive fulcrum portion being provided at an intermediate point along the length of said elongate supply conductor.

2. A system according to claim 1, wherein the actuator member has an insulating projection which, in the disconnected position of the movable and fixed contact members is located therebetween.

3. A system according to claim 1 or 2, wherein the actuator member engages a surface of the movable contact member which comprises a locating recess at a central region thereof and a locating means at each side of the recess, the arrangement being such that the actuator member is located with a first of said locating means in a first pivotal position of the actuator member, with said locating recess in a second pivotal position of the actuator member, and with the other of said locating means in a third pivotal position of the actuator member.

4. A system according to any preceding claim, wherein the fulcrum portion is formed by or at a bend in the elongate supply conductor.

5. A system according to any preceding claim wherein the distribution system comprises trunking having a cover member to which is fixed the pivot pin for the rocking actuator member.

6. A system according to any preceding claim wherein the distribution system comprises trunking containing an insulating member which is attachable to the trunking to locate the elongate supply conductor.

7. A system according to any preceding claim, the conductive fulcrum portion being provided at said intermediate point, wherein an insulating member extends between the elongate supply conductor and the fixed contact member.

8. A system according to any of claims 1 to 6, the fixed contact member being provided at said intermediate point, wherein the fulcrum portion is defined by a further conductor, an insulating member extending between the conductors.

9. An electrical distribution system as herein described with reference to Figures 1 to 3, Figure 4 or Figures 5 to 10 of the accompanying drawings.

10. As an independent invention, the additional features of any of claims 2 to 8.

11. A switch assembly comprising a rocking actuator member, a movable conductive contact member, a fixed contact member and a conductive fulcrum portion, the movable contact member being pivotable by the actuator member about the fulcrum portion between a first position, in which the movable contact member interconnects the fixed contact member and the fulcrum portion, and a second position, in which the movable contact member is disconnected from the fixed contact member, the switch assembly further comprising an elongate supply conductor, said fixed contact member or said conductive fulcrum portion being provided at an intermediate point along the length of said elongate supply conductor.

12. A rocker switch assembly comprising a rocking actuator member and a movable contact member on a fulcrum member, the actuator member engaging a surface of the contact member which comprises a locating recess at a central region thereof and a locating means at each side of the recess, the arrangement being such that the actuator member is located with a first of said locating means in a first pivotal position of the actuator member, with said locating recess in a second pivotal position of the actuator member, and with the other of said locating means in a third pivotal position of the actuator member.

13. A switch assembly substantially as herein described with reference to Figures 1 to 3, Figure 4 or Figures 5 to 10 of the accompanying drawings.