GB2320621A

GB2320621A - An electrical accessory

Info

Publication number: GB2320621A
Application number: GB9626780A
Authority: GB
Inventors: Keith Ian Davis
Original assignee: Caradon MK Electric Ltd
Current assignee: Caradon MK Electric Ltd
Priority date: 1996-12-23
Filing date: 1996-12-23
Publication date: 1998-06-24
Anticipated expiration: 2016-12-23
Also published as: GB2320621B; GB9626780D0

Abstract

An electrical accessory (1) such as a socket outlet or connection unit for which at least two differing front covers (2, 12, 14, 18) are provided and an inner member such as a shroud (30) which at least partly protrudes through the first type of cover (2) but not the second (12, 14). The arrangement is such as to provide a range of accessories with a minimum of components.

Description

An electrical accessory The present invention relates to the components used in the assembly of electrical accessories.

It is known to make a range of electrical accessories such as socket outlets and connection units that for example include unswitched and switched versions, and often other variants with additional features such as indicator lamps. For the manufacturer wishing to offer a wide range of electrical accessories, a compromise has to be achieved between providing absolutely every possible permutation and ensuring that the range is profitable to manufacture. If the manufacturer does not offer a wide enough range, customers will find the range limited, and the manufacturer will lose sales. However a wide range will necessarily include products that have very low sales which do not earn sufficient revenue to repay the cost of the tooling necessary to produce the components specific to those products. It is known to reduce this cost by careful design of components so that for instance an earth bracket may have many features to accommodate the requirements of the most complex product in the range, but some of these features will be redundant on the simpler products in the range.

It is also known to make such electrical accessories with metal front covers fitted over a inner member or shroud which provides location and insulation for the conductive parts of the accessory. With such electrical accessories it is known to produce a inner member or shroud with a mounting for a translucent lens for an indicator or warning lamp. For a complex product a corresponding hole will be provided in the front cover so that a suitably shaped indicator lens will be visible from the front of the accessory when mounted to a surface. However for a more basic product, the hole will be omitted from the metal front cover, and hence the cost of the indicator and the cost of the lens and the associated assembly costs may be saved, but the additional cost of the unused mounting for the lens will be negligible.

However, where it is necessary for part of the inner member or shroud to protrude the surface of the metal front cover, such as where it surrounds a rocker aperture, or an aperture for a flexible cable, it is necessary for the manufacturer to provide a particular inner member or shroud corresponding to each particular application. This is expensive in terms of the initial outlay on tooling and in the ongoing cost of production and stock holding.

It is an object of an embodiment of this invention to provide a component with optional features, cost effectively, that may be utilised with a complex accessory and left unused for a more basic accessory.

An electrical accessory according to the invention comprises one of at least two differing front covers and an inner member, wherein the combination of the inner member and a first said front cover is such that a portion of the inner member at least partly protrudes through the first cover at one location of the inner member, and wherein a second said front cover prevents protrusion of the inner member at the same location.

In an embodiment of the invention the front cover is made of thin metal, and it is possible to determine which optional features shall be provided on an electrical accessory simply by the choice of the front cover, where the number and arrangement of the apertures in the front cover may be simply changed during production by the use or the omission of a punch for that particular aperture. The benefit of this is that several accessories in a range may share the same inner member to an electrical component or sub assembly may be fixed. Alternatively the component may itself form the inner member. Assembly on an automatic assembly machine may be further facilitated by the fact that until the front cover is fitted the sub-assemblies may be interchangeable. Hence it is also possible in the course of manufacturing to hold partially assembled electrical accessories, and simply finish them by adding the required front cover and any of the optional parts needed to make a particular variant in the range.

The benefit of this is that the ongoing costs of production arising from the cost of holding stock of sub-assemblies and components may be reduced. A manufacturer may also be able to reduce lead times and be able to further increase the number of low volume variants from the standard products that he is able to offer.

Preferably the inner member is made of an insulating material such as a plastics material, and preferably the material is such that when made with thin sections it may be flexed without fracturing, so that the portion of the inner member may be positioned in one position relative to the rest of the inner member when it protrude, and positioned in a second position relative to the rest of the inner member when it does not protrude.

An important consideration when designing electrical accessories is to ensure that tolerances and dimensions are such that the relative positions of various components such as fuse holders and indicator lens are always positioned in a desired position relative to a front face of the front cover. Problems arise where the manufacturer desires to use the same components with say a white plastic front cover - which is relatively thick, and a metal front cover - which is relatively thin. In such cases it is necessary to take steps to ensure that the said same components which must be positioned relative to the front face of the front cover have a means provided to space them away from the front surface when used with the thin metal front cover.

Preferably the means to space them away is the inner member.

An embodiment of the invention will now be described by reference to the accompanying drawings, where: Figure 1 shows a front perspective view of one of a range of fused electrical connection units, and a front cover with a flex outlet aperture, at which a portion of an insulating shroud may be seen protruding the front cover; Figure 2 shows an enlarged scrap front perspective view of a portion of the insulating shroud of Fig. 1; Figure 3 shows a front plan view of the insulating shroud of Fig. 1; Figure 4 shows a front plan view of a front cover with a single aperture for a fuse holder; Figure 5 shows a front plan view of a front cover with an aperture for a fuse holder and an aperture for a indicator lens; Figure 6 shows a front plan view of a front cover with an aperture for a fuse holder and an aperture for a flex outlet; Figure 7 shows a front plan view of a front cover with an aperture for a fuse holder, an aperture for a indicator lens, and an aperture for a flex outlet; Figure 8 shows an enlarged front plan view of the shroud shown in Fig. 2; Figure 8A shows a section taken on line XX of Fig. 8 where the shroud protrudes a first front cover; Figure 8B shows a section taken on line XX of Fig. 8 where the shroud does not protrude a second front cover; and Figure 9 shows an exploded perspective view of the main components of the electrical connection unit shown in Fig. 1.

An electrical accessory 1 as shown in Fig. 1 comprises a metal front cover 2, a mounting box 3, two screws 4 and 5 for securing the front cover to the mounting box, and an inner member, in this case a shroud 30 that protrudes the metal front cover 2 at a fuse aperture 10 and at a flex outlet aperture 11. Mounted within a fuse-holder aperture 32 is a fuse-holder 6 and a jacking screw 7 to facilitate the opening and closing of the fuse-holder to permit replacement of a fuse (not shown).

The electrical accessory 1 is part of a range of similar electrical accessories and is known as a fused connection unit with a flex outlet. Connection units are used for connecting electrical appliances such as immersion heaters and night storage heaters to the mains supply. Depending on whether the appliance is positioned adjacent to the connection unit, in which case the flexible cable to the appliance may be required to exit the connection unit through a flex outlet in the connection unit, or alternatively if the appliance is remote from the connection unit, or in a hostile environment the flexible cable to the appliance may leave the connection unit via a conduit connected to the mounting box 3. Fig. 6 shows a plan view of the metal front cover 2. Figs 4, 5 and 7 show alternative configurations for the metal front cover that are used for making other fused connection units in the range. Fig. 4 shows a front cover 12 which is provided with only a fuse aperture 10, hence using this front cover produces a fused connection unit without the flex outlet. Fig. 5 shows a front cover 14 which is provided with a fuse aperture 10 and an indicator aperture 16, and Fig. 7 shows a front cover 18 which is provided with all three of the apertures 10,11 and 16. Hence the front cover 18 is used to make a fused connection unit with an indicator and with a flex outlet. For each of these connection units the same shroud 30 shown in plan view in Fig. 3 is used. Shroud 30 is provided with a fuse-holder aperture 32 through which the fuse-holder 6 shown in Fig. 1 and Fig. 9 protrudes; an indicator lens aperture 34 being a location to receive an indicator lens (not shown); and a flex outlet 36.

Flex outlet 36 is shown enlarged in Fig. 2, and comprises a hole 38 that is partially obstructed by vanes 40 and 42 which are attached by a narrow neck 44 and 46 (46 is visible in Fig. 8) to an inside wall 48 forming the hole 38. The hole 38 is formed within a short cylindrical section 50 having the inside wall 48, an annular front surface 52, an outer cylindrical surface 54 and a rear face 56. The cylindrical section 50 is attached to the surrounding shroud 30 by deformable mounting means, in this case deformable straps 58, 60 and 62. Spaces 64, 66 and 68 ensure easy manufacture and ensure that the short cylindrical section 50 is able to be moved relative to the shroud 30 in an axial direction FF.

The vanes 40 and 42 are provided to partially block the hole 38 of the flex outlet 36.

The narrow necks 44 and 46 are such that when a flexible cable is inserted into the flex outlet (in the direction of arrow B) the vanes 40 and 42 may be deflected inwards to open the hole 38 enough to allow the cable insertion. If desired it is also possible to remove the vanes completely by breaking them off at or by cutting through the narrow necks 44 and 46. The benefit of vanes 40 and 42 are that when no flexible cable or only a flexible cable with a small cross sectional area is inserted in the flex outlet the hole 38 the appearance of the accessory is improved.

Fig. 8 shows a front plan view of the same flex outlet 36 portion of the shroud 30 that is shown in Fig. 2. Figures 8A and 8B show a sectional view of the same flex outlet 36 taken on XX of Fig. 8. In Fig. 8A the flex outlet 36 is shown mounted to a first front cover 19 which has been made with the flex outlet aperture 11 as in front covers 2 and 18. It can be seen that the annular front surface 52 may protrude the front cover 19 through the flex outlet aperture 11. The short cylindrical section 50 is a portion of the shroud that may at least partly protrude through the front cover 19.

In Fig. 8B the same flex outlet is shown mounted to a second front cover 13 which has been made without a flex outlet aperture as in front covers 12 and 14. In this case it can be seen that the annular front surface 52 is forced in the direction of arrow B by a rear surface 15 of front cover 13. The shroud 30 has a front face 80 which butts against rear surface 15. Comparing Figs. 8A and 8B it can be seen that the relative movement of the short cylindrical section 50 with respect to the shroud 30 has resulted in the deformation of the deformable strap 60, and likewise deformable straps 58 and 62 (not shown in deformed state). In both Fig. 8A and 8B the front face 80 butts against rear surface 15, hence the shroud in each case is mounted to the front cover in the same relative position with respect to the front surface 21 of the frontplate.

From Fig. 9 the main components of the electrical connection unit shown in Fig. 1 may be seen to comprise the front cover 21, the shroud 30, and a base assembly 100. Base assembly 100 comprises a base 102 to which is mounted fuse-holder 6 and an earth bracket 104 with fixing holes 106 and 108, a front component 120 and a cord grip 110. The electrical connection unit is assembled by mounting the base assembly 100 to the front cover 2 so that the shroud 30 is sandwiched in-between them. The base is retained to the front cover by two tubular eyelets 112 (only one shown) which pass through fixing holes 8 and 8' in the front cover and through fixing holes 70 and 72 respectively in the shroud and then through fixing holes 106 and 108 in the earth bracket 104. The eyelets are deformed to ensure that the earth bracket is retained to the front cover. The eyelets have a fixing hole 114 to receive fixing screws 4 and 5 shown in Fig. 1. A front face 116 of the cord grip 110 butts against the rear face 56 of the cylindrical section 50 when they are assembled, ensuring that the short cylindrical section 50 is retained in the position shown in Fig. 8A. The fuseholder 6 is arranged such that when the base assembly 100 is assembled to the front cover the front surface 20 of the fuse-holder is substantially flush with a surrounding front surface 74 of the shroud 30 and the front surface 21 of the front cover. Since as shown in both Fig. 8A and 8B the front face 80 butts against rear surface 15, ensuring the shroud in each case is mounted to the front cover in the same relative position with respect to the front surface 21 of the frontplate the fuse-holder will be substantially flush with the surrounding front surface 74 of the shroud 30 and the front surface 21 of the front cover when assembled with any one of the frontplates 12,14, 2 or 18.

In a similar manner to the flex outlet, the indicator lens aperture 34, is attached to the shroud by deformable straps 76, 77, 78 and 79, and in the case of the front cover shown in Fig. 9 will be displaced relative to the shroud on assembly. However, where used with either front cover 14 or 18, the indicator lens aperture 34 is retained in a protruding manner by an indicator lamp assembly (not shown) that is inserted into location 118 of the base 102.

The benefits of using a shroud 30 with portions such as the flex outlet 36 that may or may not be utilised are that since one component shroud is used on more than one configuration of electrical accessory, there is a reduction in the number of components that the manufacturer needs to manufacture and stock. This has a significant effect on production economics as non-productive time in tool changes is reduced. Stock holding costs are reduced, as records are only required fro one component. Further, since the shroud performs a protective insulating function protecting a flexible cable passing through the hole 38 from the potentially sharp edge of the flex hole aperture 11 in the front cover, costs may be saved on finishing the front cover. In addition the various component parts of the base assembly 100 such as the cord grip 110 may be used with a moulded plastics front cover (not shown) instead of the shroud and front cover combination described above, where by its nature the plastics front cover has a protected insulated hole corresponding to hole 38. This enables the manufacturer to improve the utilisation of assembly equipment.

Although the inner member has been described in terms of a separate shroud, it is possible that in a second embodiment the inner member is part of an electrical component having a base assembly similar to that shown in Fig. 9 at 100. In this case an inner member will be formed as part of a front component corresponding to front component 120 shown in Fig. 9.

Although the inner member has been described in terms of a shroud made of an insulating plastics material, it is possible that in a third embodiment to arrange that the insulation required is provided by other components, such as the front component 120 shown in Fig. 9, in which case the inner component could be made of metal, and the front cover could be made of metal or of plastics, and may not completely cover the front of the inner component.

Claims

1. An electrical accessory comprising one of at least two differing front covers and an inner member, wherein the combination of the inner member and a first said front cover is such that a portion of the inner member at least partly protrudes through the first cover at one location of the inner member, and wherein a second said front cover prevents protrusion of the inner member at the same location.

2 An electrical accessory as claimed in claim 1 wherein the two differing front covers are substantially metal.

3 An electrical accessory as claimed in claim 1 or 2 wherein the inner member is made of an insulating material.

4. An electrical accessory as claimed in claim any one of the preceding claims wherein the portion of the inner member comprises an outlet for a flexible cable.

5. An electrical accessory as claimed in claim 4 wherein the outlet for a flexible cable is partially blocked by at least one vane.

6. An electrical accessory as claimed in claim 5 wherein the vane may be deflected by the insertion of a flexible cable.

7. An electrical accessory as claimed in any one of claims 1 to 3 wherein the portion of the inner member comprises a location for an indicator lens.

8. An electrical accessory as claimed in any one of claims 1 to 6 wherein the inner member has a further portion which comprises a location for an indicator lens.

9. An electrical accessory as claimed in any one of the preceding claims wherein the or each portion is mounted to the inner member by a deformable mounting means.

10. An electrical accessory substantially as described with reference to the accompanying drawings.