GB2376798A

GB2376798A - Switch

Info

Publication number: GB2376798A
Application number: GB0115011A
Authority: GB
Inventors: Electric Limited Mk; Glenn Robert Page
Original assignee: MK Electric Ltd
Current assignee: Novar ED&S Ltd
Priority date: 2001-06-20
Filing date: 2001-06-20
Publication date: 2002-12-24
Anticipated expiration: 2021-06-20
Also published as: GB2376798B; GB0115011D0

Abstract

An electrical switch 1 comprises a rocker 5 for operating the switch pivotably mounted to a body 4. The rocker has a width 1W in a direction of an axis NN of the pivotable movement of the rocker being not less than a width 1X of the body in the said direction. The switch is arranged to fit within an aperture 2P, the body having a rear facing surface 51 for abutting a front facing surface 52 of a frontplate 2.

Description

Improvements in and relating to electrical wiring accessories The present invention relates to electrical switches, having a rocker switch operating member.

Electrical wiring accessories such as switches for use in domestic, commercial and similar applications are frequently required in alternative configurations, such as single and multiple gang switches, and one or two way switches. A manufacturer is expected to provide an extensive range of switches covering all the possible permutations, however, such a range normally requires a relatively large number of components, of which many are specific to particular configurations of a switch. This is a cause of high manufacturing costs.

According to the present invention, there is provided an electrical switch comprising a rocker for operating the switch pivotably mounted to a body, the rocker having a maximum width in a direction of an axis of the pivotable movement of the rocker being not less than a maximum general width of the body in the said direction, the electrical switch being arranged to fit within an aperture, the body having a rear facing surface for abutting a front facing surface of a frontplate.

A benefit of this is that the size of the body may be minimised, and hence available wiring space within a mounting box to which the switch is mounted may be increased.

A further benefit is that the number of components required to make the switch may be reduced, since a front cover or bezel arranged to fit around the rocker is not required. Hence, both costs associated with the extra components may be

saved, and problems associated with ensuring colour matching of visible components is reduced.

Preferably the electrical switch is mounted to a frontplate.

More preferably the frontplate has a rear facing surface for abutting a mounting and a front facing surface for abutting the rear facing surface of the body, the frontplate having an aperture for receiving the electrical switch.

A benefit of this is that safety is enhanced, as it is not possible to dislodge or remove the front part or the electrical switch from the front when it is mounted to a frontplate.

A further benefit is that excessive force applied from the front of the electrical accessory is resisted by the electrical switch abutting the second front surface of the frontplate.

Preferably the body and the frontplate are arranged such that the switch is mounted to the frontplate by insertion from the front of the frontplate.

A benefit of this is that the switch may be more easily mounted to the frontplate. A further benefit is that a switch where the rocker has a larger width than the body may be assembled and tested before being mounted to a frontplate.

Preferably an external surface of the rocker is arranged to fit within an inwardly facing surface of the aperture.

A benefit of this is that the number of visible components may be reduced, and hence a problem associated with colour matching of the visible component is eliminated.

Preferably the body is arranged to resiliently deform outwardly to receive the rocker.

A benefit of this is that the rocker may be easily assembled to the body, and an inwardly facing surface of the aperture in the frontplate may preferably provide support for the body to resist the rocker being disengaged from the body.

A benefit of this is that the rocker is securely retained to the electrical switch, when the electrical switch is mounted to the frontplate.

Preferably the body has terminals arranged so that holes for receiving electrical conductors for making electrical connections open substantially to one side of the electrical switch.

Preferably the body has terminals arranged so that terminal screws for securing electrical conductors face substantially to another side of the electrical switch.

A benefit of the terminals being arranged so that holes for receiving electrical conductors open substantially to one side of the electrical switch and the terminal screws face to the other side is that an installer may easily see from one side to insert electrical conductors and then tighten from the other side, without the installer having to move or rotate the switch and risk dislodging the electrical conductors in the process.

A further benefit of the terminals being arranged so that holes for receiving electrical conductors open substantially to one side of the electrical switch and the terminal screws face to the other side is that such an electrical switch may be fitted into a shallow mounting box without having to bend the electrical conductors fitted to the terminals sharply close to the terminals. Hence safety is improved since there is a reduced risk of displacing insulation from the electrical conductor and exposing a bare electrical conductor at a cut end of the insulation,

and also ease of installation is improved since the installer does not have to apply excessive force to bend or flatten electrical conductors as the switch is inserted and mounted with mounting screws to the mounting box.

Preferably the terminals once inserted into the body are retained to the body by means of a resiliently deformable portion of the body.

A benefit of this is that no additional component is required to retain the terminals to the body.

Preferably retaining means are provided in the body that are arranged to resist axial and rotational forces arising from use of a screwdriver to apply a tightening torque to the terminal screws.

Still more preferably retaining means are provided in the body that are arranged to resist any displacement of the terminals arising from a force applied by means of such electrical conductors clamped to the terminals.

Preferably a direction of insertion of the terminals into the body is at an obtuse angle to both an axis of the terminal screws and an axis of a hole for receiving electrical conductors.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which :- Figure 1 is an exploded perspective view of a plateswitch with a first electrical switch according to the invention;

Figure 1 A is an enlarged portion of Figure 1, showing a detail of a clip feature of Figure 1; Figure 2 is a perspective view showing a section through an assembly of the frontplate and electrical switch shown in Figure 1 (section lines omitted for clarity) ; Figure 3 is a perspective view from the front of a body for an electrical switch according to a second embodiment of the invention; Figure 3A is a perspective view from the rear and one side of the body shown in Figure 3; Figure 3B is a perspective view from the rear and the other side of the body shown in Figure 3; Figure 3C is an enlarged portion of Figure 3A, showing a detail of a deformable rib shown in Figures 3A and 3B ; Figure 4 is a perspective view from the rear of a terminal for an electrical switch according to the second embodiment of the invention; Figure 5 is a sectioned view showing an assembly of the terminal shown in Figure 4 to the body shown in Figure 3 viewed in the direction of arrow 5V; Figure 6 is a rear perspective view of a two gang plateswitch having two electrical switches according to a third embodiment of the invention showing electrical wires for making electrical connections to the switches when the plateswitch has been mounted to a mounting box; Figure 7 is a front view of a four gang plateswitch having four electrical switches according to a fourth embodiment of the invention; Figure 7A is a side view of the plateswitch shown in Figure 7 showing terminal screws;

Figure 7B is a side view of the plateswitch shown in Figure 7 showing apertures for inserting electrical conductors; and Figure 7C is a rear view of the plateswitch shown in Figure 7.

In Figure 1, an electrical plateswitch 1 is shown, comprising a frontplate 2 and an electrical switch 3. The electrical switch 3 comprises a body 4, to which is mounted a rocker 5. The body is adapted to receive terminals 6,7 and 8, each terminal having an aperture 10,10'and 10", each for receiving an electrical wire and each having a threaded hole 9,9'and 9"each for receiving a screw 11, 11' and 11"respectively for clamping the wires. Corresponding apertures are provided in the body to permit the electrical wire and screw to be inserted into each of the terminals as required, only the screw apertures 50,50'and 50" being visible in Figure 1. A moving contact 12 is located by ears 13 and 14 in a pair of locations 15 (only one visible in Figure 1) in the body. The rocker is provided with a hole to receive a spring 17 and a plunger 18. When the rocker is mounted to the body the spring urges the plunger resiliently in an axial direction of the plunger, against the moving contact 12.

The body is provided with resilient clip features 20 and 21. From the enlarged view in Figure 1 A, the resilient clip feature 20 may be seen to protrude a perimeter profile 1 P of the body by a dimension 1 Q, and is provided with engaging face 22 and ramp portion 24. The other resilient clip feature 21 corresponds.

Rocker 5 has two protruding pivots 40 and 41 (only one visible in Figure 1), which are received in holes 42 and 43 of the body 5, so that the rocker may be pivotably operated about an axis NN from a first state to a second state.

The rocker 5 is one piece, having thereon a digital manipulation surface facing to the front for operating the switch from the first state to the second state, for example ON or OFF.

The rocker has a width 1W and a length 1 R measured across a perimeter profile 5P. The switch body 4 has a general maximum width 1 X measured across the perimeter profile 1 P and a general maximum length IS measured across the perimeter profile 1 P (but excluding the resilient clip features 20 and 21, which because of their resilience may be deflected to be within the length of the body at the perimeter profile 1 P). The frontplate 2 has a width 2W and a length 2R across internal dimensions of an internal profile 2P of the aperture 65 of the frontplate 2.

In an alternative embodiment of the invention not shown in the drawings, resilient clip features corresponding to clip features 20 and 21 are provided to the sides of the body, and may because they are resilient extend beyond the general width when un-constrained.

Rocker width 1 W is not less than the width 1 X.

Preferably rocker length 1 R is not less than body length IS, and more preferably rocker length 1 R is not less than a length 1 T measured over the free length of the resilient features 20 and 21.

To enable the switch to operate, rocker 5 must be a clearance fit within the aperture 65, hence rocker width 1W must be greater than aperture width 2W.

Preferably the clearance should be more than 0.25 mm and less than 0. 1 Omm.

A benefit of such clearances is that they enable the operation of the switch, but do not permit dangerous access to live components with an every day object such as a paper clip.

From Figure 2, the electrical plateswitch 1 of Figure 1, is shown with the electrical switch 3 mounted to the frontplate 2. The body 4 is retained to the frontplate by the engaging faces 22 and 23 of resilient clip features 20 and 21 engaging the detents 55 and 56 respectively. Body 4 locates with rear face 51 abutting forward face 52 of the frontplate 2 such that movement arising from a force in the direction of arrow 2F is resisted.

Figure 3 shows a perspective view from the front of a body 300 for an electrical switch according to a second embodiment of the invention. The body 300 is assembled to a rocker and other switch component parts and subsequently a frontplate in a similar manner to that of body 4.

Body 300 has pockets 306,307 and 308 to receive terminals similar to terminals 6,7 and 8. Apertures 316,317 and 318 are provided in the body to permit electrical conductors to be inserted into each of the terminals as required, and screw apertures 326,327 and 328 are provided to enable terminal screws (corresponding to screw 11 of Figure 1) to be tightened. Pocket 306 is provided with ribs 371 and 372, and pocket 308 is provided with ribs 373 and 374, the ribs being arranged to provide an interference fit with a terminal when the terminal is inserted into the respective pocket.

A pair of locations 314 and 315 are formed in the body by upstanding walls 320,321, 322 and 323 to provide locations for ears of a moving contact (similar to moving contact 12). The body is also provided with holes 342 and 343, to pivotably retain a rocker (similar to rocker 5) for operation in a like manner to that described with reference to Figure 1. The body has external side faces 344 and 345 adjacent to each of holes 342 and 343 respectively.

The body is provided with resilient clip features 331 and 332. These correspond to the resilient clip feature 20 and 21 of Figure 1 to enable the body to be

mounted and retained in an aperture of a frontplate such as frontplate 2 of Figure 1.

In a similar manner to that described above with reference to Figure 2, the body 300 is retained to a frontplate by the engaging faces 362 and 363 of resilient clip features 331 and 332 engaging corresponding detents on the frontplate.

Body 300 locates with rear face 351 abutting a forward face of the frontplate such that movement arising from a force applied to a rocker is resisted. A benefit of this is that safety is improved, as it is not possible to dislodge the body from the frontplate by applying pressure to the rocker of the electrical switch.

From Figures 3A and 3B, the body may be seen to be provided with similar deformable ribs 30,31, 32 and 33 at each corner. Deformable rib 32 is shown enlarged in Figure 3C, the rib having a spine 32S, protruding from external surface 35 by a height 32H. On assembly of the body to a frontplate, the body is inserted in an aperture with an internal surface which surrounds the external surface 35 of the body, so as to locate the body within the aperture. However, since a tolerance must be allowed on both an external dimension 35D of the external surface 35 and on the corresponding internal dimension of the frontplate aperture, it is not possible to always achieve a desired close fit of the body to the frontplate so that there is no perceivable relative movement between the two, while at the same time always providing dimensions that will permit the easy insertion of the body into the frontplate. Deformable ribs 30,31, 32 and 33 are arranged such that the height of the ribs above the surrounding surface is sufficient to ensure that when there is the maximum clearance between the body and frontplate the ribs assembly of the body to the frontplate will result in a deformation of the spine of the rib sufficient to ensure that in normal operation, a user may detect no relative movement between the body and frontplate. Hence, a benefit of these ribs is that clearance between an internal dimension of the aperture in the frontplate and an external dimension of the body which is

necessary for manufacturing tolerances and easy assembly, does not result in the module being loose when mounted to the body. Hence a perceived quality of the switch assembly is enhanced.

Figure 4 shows a perspective view from the rear of a terminal 400 for the electrical switch according to the second embodiment of the invention. Terminal 400 comprises a section of brass extrusion 402, with a threaded hole 404 to receive a terminal screw (such as screw 11 in Figure 1) and hole 406 for receiving an electrical conductor. The brass extrusion 402 has a side face 408, an opposing side face 412 and a recessed face 410, and a bottom face 414. A step 416 is provided on face 418.

In Figure 5 a sectioned view of the terminal 400 shown in Figure 4 from which may be seen a contact 420 welded to a top face 422 so as to provide good electrical conductivity. The terminal 400 may be seen to have an included angle

5A between a centre line 5C of threaded hole 404 and a centre line 5B of hole 406. Preferably the included angle 5A is greater than 90 degrees, and more preferably it is 105 degrees. Preferably an angle 5G between a plane parallel with a mounting surface and the centre line 5C is 30 degrees, and an angle 5H between the said parallel plane and the centre line 5B is 45 degrees. A benefit of an included angle greater than 90 degrees is that the ease with which electrical conductors may be inserted in the hole 406, and the ease with which a terminal screw in threaded hole 404 may be tightened is improved, particularly when the switch is used in a shallow box, such as the box 524 shown in Figure 6, and a limited free length of the conductors prevents the switch being moved sufficiently far away from the shallow box to rotate the switch so that a rear of the switch is easily accessible.

When tightening a terminal screw a screwdriver (not shown) is located axially along centreline 5C, and a force 5F is applied to ensure the screwdriver remains

in engagement with the terminal screw, and a tightening torque 5T is applied until sufficient clamping force has been applied to ensure good electrical contact between the terminal and an electrical conductor. A benefit of the arrangement described herein for retaining the terminal in the pocket of the body, is that the terminal is securely located and restrained from any relative movement with respect to the body, a benefit of this is that an installer is better able to judge when an adequate tightening torque has been applied to a terminal screw, and hence a hazard arising from a high electrical resistance between the conductor and the terminal is avoided.

In Figure 5 the terminal 400 is shown assembled to the body 300 shown in Figure 3. The terminal 400 is assembled to the body by inserting it into pocket 306 in the direction of arrow 5R, so that opposing side face 412 is forced past resilient retaining protrusion 424 until it is located abutting recessed face 426.

The side face 408 abuts ledge 422 to resist the force arising from the deflection of resilient retaining protrusion 424.

An outline of a cross-section through a centre-line of a rocker 450 is shown in a dotted line in Figure 5. The rocker 450 has a top face 452 for digital operation of the switch and side faces 456 and 458 with a dimension 5W across the side faces. The rocker also has protruding pivots 454 and 455 which locate respectively in holes 342 and 343 in the body. The rocker also has a hole 460 for receiving a plunger and spring (similar to plunger 18 and spring 17 of Figure 1), and a location 462 to locate the spring.

An outline of a cross-section through a centre-line of a mounting plate 468 is shown in a dot-dash line in Figure 1. The mounting plate has a front surface 471 and an aperture 470, the aperture having an internal dimension 5Y. The mounting plate has a forward face 473 arranged to abut the rear face 351 of the body when the body is mounted to the mounting plate.

The body has a maximum dimension 5X across the side faces 344 and 345.

The dimension 5W is arranged to be not less than the dimension 5X.

The dimension 5Y is arranged to be greater than dimension 5W, to allow sufficient clearance for the operation of the rocker.

From Figure 6 a rear perspective view of a second electrical switch 501 according to a third embodiment of the invention is shown with electrical wires 520 for making electrical connections to switches 503 and 504 which are mounted to a frontplate 502. Each switch has screws 506 and 508 to enable electrical connections to be made to the wires inserted in the terminal apertures 510 and 512 in a similar manner to that described with reference to the first embodiment. Figure 6 also shows an electrical conduit 522, that in a typical installation for a domestic light-switch would be buried in a plaster coat of a wall and would extend vertically above a centre knockout 523 of a mounting box 524 (outline shown in a dashed line in Figure 6 for clarity), and a typical arrangement of the wires leaving the switches 503 and 504 and entering the conduit are shown. It may be seen that a benefit of the embodiment of Figure 6 is that the wires are easily contained within such a shallow box, which typically would have a depth 5D of 16mm.

From Figures 7, 7A, 7B and 7C a four gang plateswitch 700 according to a fourth embodiment of the invention is shown having four electrical switches 701,702, 703 and 704 mounted to a frontplate 705. Each switch has a rocker 721, 722, 723 and 724 and a body 725,726, 727 and 728, and further comprises terminals 731,732, 733,734, 735 and 736 (visible in Figure 7B), each terminal having an aperture 741,742, 743,744, 745 and 746 (visible in Figure 7B) and a terminal screw 751,752, 753,754, 755 and 756 (visible in Figure 7A). A British Standard mounting box 710 (shown in dotted lines) according to BS 4662: 1970 at page 7, Figure 1 b - Electrical accessory box: size UA 1 has dimensions, width 7W being 68.3mm minimum, height 7H being

68.3mm minimum, and depth 7D being 16mm. The box also has a minimum width between lugs of 52mm. The four electrical switches are arranged to fit within these dimensions, and due to the compact dimensions of the electrical switches adequate space remains for electrical conductors to be fed from an electrical conduit 712 through the box to the switch terminals.

The fourth embodiment shows that a benefit of the compact arrangement of the switch is that a four gang plateswitch may be made using four electrical switches according to the invention. Hence, not only are cost savings made in the course of manufacture, arising from the use of common parts, but also the flexibility of the manufacturing process is improved as electrical switches may be assembled and tested before being mounted to a frontplate to obtain a required plateswitch configuration.

Although Figure 1 shows the rocker as a one piece plastics moulding, in an alternative embodiment of the invention, the rocker can have a separate cover, such as a metallic cover, or coloured inserts, without compromising the integral nature of the rocker as a whole. That is the rocker is still in effect an integral single component having a front facing surface for digital manipulation between two states, such as ON or OFF, the maximum width of the rocker being not less than the general maximum width of the body.

Claims

CLAIMS 1. An electrical switch comprising a rocker for operating the switch pivotably mounted to a body, the rocker having a maximum width in a direction of an axis of the pivotable movement of the rocker being not less than a maximum general width of the body in the said direction, the electrical switch being arranged to fit within an aperture of a frontplate, the body having a rear facing surface for abutting a front facing surface of the frontplate.
2. An electrical switch as claimed in claim 1, the electrical switch including the frontplate.
3. An electrical switch as claimed in claim 2, wherein the body and the frontplate are arranged such that the switch is mounted to the frontplate by insertion from the front of the frontplate.
4. An electrical switch as claimed in claim 2 or 3, wherein an external surface of the rocker is arranged to fit within an inwardly facing surface of the aperture.
5. An electrical switch as claimed in any one of the preceding claims, wherein the body is arranged to resiliently deform outwardly to receive the rocker.
6. An electrical switch as claimed in any one of the preceding claims, wherein the body has terminals arranged so that holes for receiving electrical conductors for making electrical connections open substantially to one side of the electrical switch.
7. An electrical switch as claimed in claim 6, wherein the body has terminals arranged so that terminal screws for securing electrical conductors face substantially to another side of the electrical switch.

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8. An electrical switch as claimed in claim 6 or 7, wherein the terminals are arranged to be retained in the body by means of a resiliently deformable portion of the body.
9. An electrical switch as claimed in claim 8, wherein retaining means are provided in the body that are arranged to resist axial and rotational forces arising from a the use of a screwdriver to apply a tightening torque to the terminal screws.
10. An electrical switch as claimed in claim 1, wherein retaining means are provided in the body that are arranged to resist any displacement of the terminals arising from a force applied by means of such electrical conductors clamped to the terminals.
11. An electrical switch as claimed in claim 1, wherein a direction of insertion of the terminals into the body is at an obtuse angle to both an axis of the terminal screws and an axis of a hole for receiving electrical conductors.
12. An electrical switch as claimed in any one of claims 2 to 11, wherein the aperture is arranged to abut a side face of the body adjacent to a mounting of the rocker.
13. An electrical switch as claimed in any one of the preceding claims, wherein the switch further comprises more than one electrical switch mounted to the frontplate.
14. An electrical switch, substantially as hereinbefore described and with reference to the accompanying drawings.