GB2293925A

GB2293925A - Cable clamp of component

Info

Publication number: GB2293925A
Application number: GB9419987A
Authority: GB
Inventors: Paul Bollinghaus; Martin Anthony Serrao
Original assignee: CONTACTUM Ltd
Current assignee: CONTACTUM Ltd
Priority date: 1994-10-04
Filing date: 1994-10-04
Publication date: 1996-04-10
Anticipated expiration: 2014-10-04
Also published as: GB2293925B; GB9419987D0

Abstract

An electrical component comprising a front-plate (1) to the rear face of which a housing (2) for the electrical connector is attached. Cable access openings (3, 4) are provided different planes, for example in either the front face and/or the peripheral edge of the front plate (1), to provide access for an electric cable to the rear of the front plate in two planes at 90 DEG to each other. A movable cable clamping member (10) having a cable gripping portion (11) is laterally movable with respect to both cable access openings (3, 4) by moving means (17) arranged so that when a cable is inserted in either of the cable access openings (3, 4), the cable is gripped between a fixed abutment (7) and the cable engaging portion (11) of the movable clamping member to prevent withdrawal of the cable from the front plate (1). <IMAGE>

Description

TWO-WAY CABLE CLAMP FOR ELECTRICAL COMPONENTS This invention relates to electrical components and more particularly to components of the type having a front plate with an access aperture for the electric supply cable in either the front face or in the peripheral side wall thereof, the supply cable being held in position in the access opening by cable clamping means which prevent its subsequent removal.

Prior art electrical components of this type have either front or side access for the electric supply cable which means that a different component has to be manufactured for each design using differently configured front plates and cable clamping assemblies. This increases the manufacturing costs due to the large number of different parts which need to be made for the two designs and also stock levels are doubled which is undesirable.

It is an object of the invention therefore to provide an electrical component which overcomes or substantially reduces the disadvantages of the prior art by including cable clamping means enabling front and/or side entry of the electric supply cable.

According to the invention there is provided an electrical component comprising a front plate, a housing for the electrical connectors attached to the rear face of said front plate, a cable access opening in the front face and/or peripheral edge of the front plate to provide access for an electrical cable to the rear of the front plate, a movable cable clamping member arranged adjacent said cable access opening and shaped to allow a cable inserted in the access opening to pass therethrough in one of at least two different planes, said cable clamping member also including a cable gripping portion and being movable laterally with respect to the cable access opening by moving means arranged so that when a cable is inserted in the cable access opening, the cable passes through the cable clamping member and is gripped by said cable engaging portion of the movable clamping member to prevent withdrawal of the cable from the front plate.

Preferably, the cable can pass through the clamping member in two planes which are arranged at 900 to each other but other angular configurations could be provided depending on the location of the cable access opening in the front plate.

Furthermore, the cable clamping member could be shaped to receive cable in more than two directions.

Preferably a fixed abutment is provided against which the cable is, clamped the projection being formed on the rear face of the front plate but it can also be formed on the housing if required.

Desirably the cable gripping portion of the movable clamping member is located at one side of the cable access opening and the fixed abutment is located at the opposite side of said opening.

In a preferred embodiment, the cable clamping member is a movable carriage, the cable gripping portion being provided adjacent one end of said carriage. Preferably an upstanding projection or end stop extends from the carriage for engagement by the moving means. In a preferred embodiment, said upstanding projection or end stop is located at the end of the carriage remote from the cable gripping portion thereof.

In another embodiment, the moving means is a screw which acts on said upstanding projection, rotation of the screw resulting in the free end thereof bearing against the upstanding projection to move the carriage relative to the front plate and thereby cause the cable gripping section of the carriage to tightly grip a cable inserted in either of the access openings. The carriage moving means can however be a spring arrangement which acts on the carriage to bias the carriage in a direction whereby the cable gripping means normally grips a cable inserted in either of said cable access openings.With this arrangement, the cable gripping portion would be biased into a position which partially blocks the access opening so an installer would need to insert a sharp implement into the access opening and push the cable gripping portion back to expose the access opening so that the cable can be inserted therein. Once the sharp implement has been removed from the opening, the biasing force of the spring will urge the carriage back to its rest position and bring the cable engaging portion of the carriage into engagement with the cable to clamp it in position in the front plate and prevent its removal therefrom.

In a preferred embodiment, the carriage has an aperture therethrough shaped to allow a cable inserted in either of said access openings to pass through the carriage past said cable gripping portion. Conveniently the carriage includes an outrigger which extends partially around the opening in the front face of the front plate between the cable gripping portion and the remainder of the carriage connected thereto and between the front and side cable access openings.

Preferably the outrigger engages the interior face of the peripheral side wall of the front plate which acts as a guide therefor. In an alternative embodiment, a guide channei or rebate is formed in the side wall of the front plate to slidingly receive said outrigger and provide a more positive guide therefor.

Preferably the carriage includes a bearing portion slidably supported on the fixed abutment, said bearing portion being located relative to the fixed abutment by a projection or flange formed on the housing or the front plate, the bearing portions sliding between the fixed abutment and said projection or flange.

In one preferred arrangement, the carriage moving means is a screw which is mounted in a tapped hole provided in a tab extending from the housing. In another arrangement however, the electrical component includes an earthing strap which is fitted to the housing and the screw is mounted in a tapped hole provided in a tab formed as part of said earthing strap.

Preferably two sets of cable gripping formations orientated in different directions at 90" to each other are provided on the fixed abutment, the first set of formations being adapted to engage a cable and prevent removal thereof from the front access opening and the second set of formations being adapted to engage and prevent removal of a cable from the access opening in the peripheral edge of the front plate.

Conveniently the movable member or carriage is moulded from a rigid plastics or nylon material. It could however be made from a diecast moulded alloy.

Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a front view of an electrical component incorporating the cable clamping system of the present invention and shows two possible cable access aperture locations in the front plate and its peripheral wall; Figure 2 is a perspective view of one form of cable clamping system of the present invention provided in an electrical component having a front plate and a housing attached to the rear face thereof enclosing the electrical components; Figure 3 is a side view on an enlarged scale of the electrical component shown in Figure 2; and Figure 4 is a perspective view of an alternative embodiment.

It is to be understood that although the illustrated arrangement is a switch assembly, this is given as an example of an electrical component embodying the novel cable clamping system of the invention and it can therefore be used with other electrical components.

Referring to the drawings, Figures 1 and 3 show a switch assembly comprising a front plate 1 to the rear of which is mounted a housing 2 for the various electrical components (not shown). A front cable access opening 4 can be provided either in the front face of the front plate 1 adjacent one corner thereof or as a side access opening 3 (either preformed or of the "break-out" type) in the peripheral side wall la of the front plate 1. For convenience of illustration, both front and side access openings are illustrated but in practice only one or the other would be provided.

The illustrated switch assembly also includes a switch dolly 5 and a removable fuse holder 6 of known type so no further description thereof is necessary as they do not form part of the present invention.

Figures 2 and 3 illustrate in more detail the novel cable clamping system of the present invention. It can be seen from these Figures of the drawings that this comprises an upstanding projection 7 which provides a fixed abutment against which a cable (not shown) will be clamped when inserted in the front opening 4 or the side opening 3. The abutment or post is preferably integrally moulded with the front plate 1 but it could be formed as part of the housing 2. The face of the abutment 7 immediately adjacent the opening 4 is provided with one or more ribs 8a (only one is illustrated) orientated to be parallel with the rear face of the front plate 1, said rib or ribs being tangential to the hole 4.The post 7 also includes a second part provided with a plurality of vertically orientated ribs 8b arranged parallel to the longitudinal axis of the opening 4 and at 90" to the orientation of the rib or ribs 8a for reasons which will be explained hereafter.

The cable clamping system further includes a movable carriage 10 having a guide or slider portion 14, a cable clamping portion 11 and an opposite end wall 9. The carriage guide portion 14 extends beyond the end wall 9 as illustrated and is provided at its remote end with an upstanding projection or lug 16, the purpose of which will be described shortly.

The part of the housing 2 which lies immediately adjacent the carriage 10 is formed with a laterally extending flange 15 which is spaced from the top surface of the post 7 by a distance equal to the thickness of the carriage guide 14.

Thus, the carriage 10 can slide laterally with respect to the hole 4 along the top of the post 7 in a direction parallel to the rear face of the front plate 1. A metal tab or screw support 18 extends outwardly from the housing 2 and includes a tapped hole therein which receives screw 17. It will be appreciated that when the screw 17 is rotated, the free end 17a thereof will bear against the abutment 16 to move the carriage 10 in the direction of arrow A. The housing 2 includes a surface 2b (see Figure 3) which limits the lateral movement of the carriage 10 when the lug 16 engages with it.

The cable clamping portion 11 of the carriage 10 is connected to the end wall 9 by means of an outrigger 12 (see Figure 2). The outrigger has a side face 13 which engages with the interior face of the upstanding peripheral wall la of the front plate to give added guidance to the lateral movement of the carriage 10. The carriage 10 is further located between the side face 2a of the housing 2 and the upstanding peripheral side wall la, and side face 14a of the carriage abutting side wall 2a of the housing 2. The edge 13 of the outrigger 12 locates the other side of the carriage against the peripheral side wall la. Thus, on rotation of the screw 17, the carriage will move laterally past the openings 3 and 4 in the direction indicated by the arrow A, the carriage moving along the rear face of the front plate 1 between the housing 2 and the peripheral wall la of the front plate.

The main purpose of the outrigger 12 is to provide a structural connection between the cable clamping portion 11 and the end wall 9 so that when a cable (not shown) is inserted in either of the openings 3 or 4, and the screw 17 is tightened, the cable clamping portion 11 cannot bend outwardly and possibly fracture the carriage guideway 14.

The outrigger 12 prevents this happening by connecting the cable clamping portion 11 to the end wall 9 and maintaining its position relative thereto at all times even when considerable loads are applied to a cable (not shown) when inserted in the opening 4 or 3 as a result of tightening the screw 17.

The cable clamping system of the present invention operates in the following way. When a cable (not shown) is inserted into the access opening 4, it passes through the carriage 10 in a vertical direction as illustrated in Figure 2 and its free end can then be directed to the interior of the electrical component for connection to the terminal connectors (not shown) of the housing 2. On insertion of the cable in the opening 4, the carriage 10 will be in the position illustrated in Figure 2. Rotation of the screw 17 will bring its free end 17a to bear against the abutment 16 thereby moving the carriage 10 laterally with respect to the opening 4 in the direction indicated by the arrow A. This causes the cable engaging portion 11 to bear against the cable in the opening 4 and pushes its opposite side against the ribs 8a and thereby clamps the cable firmly in position.

If a cable is to be inserted into the electrical component using the side hole 3, much the same installation procedure is involved except that the cable (not shown) will be pushed into the electrical component through the opening 3, through the carriage 10 and past the vertical ribs 8b, the free end of the cable can then be connected to the electrical connectors (not shown) in the housing 2. In the same way as has already been described, the screw 17 is rotated which results in its end 17a bearing on the abutment 16 to move the carriage 10 laterally relative to the access opening 3 with the result that the cable gripping portion 11 pushes the cable (not shown) laterally to the left in Figure 2 in such a way that it bears against the vertical ribs 8b. Once in this clamped position, the cable cannot be removed from the assembly.

Figure 4 illustrates in more detail an alternative cable clamping system to that shown in Figures 1-3. The same reference numerals will be used for the same or similar parts. As with the earlier embodiments, both front and side cable access openings 4 and 3 are shown for ease of illustration but in practice only one or the other would be present.

As can be seen from Figure 4, an upstanding projection 7 is formed on the rear face of the front plate 1 to provide a fixed abutment against which a cable (not shown) will be clamped when inserted in the front opening 4 or the side opening 3. This abutment or post 7 is preferably integrally molded with the front plate 1 but it could be formed as part of the housing 2. The face of the abutment 7 immediately adjacent the opening 4 is provided with one or more ribs 8a (only one is illustrated) orientated to be parallel with the rear face of the front plate 1, said rib or ribs being tangential to the hole 4. The post 7 also includes a second part provided with a plurality of vertically orientated ribs 8b arranged parallel to the longitudinal axis of the opening 4 and at 900 to the orientation of the rib or ribs 8a for reasons which will be explained hereafter.

The cable clamping system further includes a movable carriage 10 having a guide or slider portion 14, a cable clamping portion 11 and an end wall 9. A cam surface 20 extends from the end of the carriage 10 immediately adjacent the hole 4 and is formed in two separate parts having a space 21 therebetween. A screw 17 is threadingly received in the front plate 1 and the head of the screw has a bevelled under-surface 17a for reasons which will be explained hereafter.

The part of the housing 2 which lies immediately adjacent the carriage 10 is formed with a laterally extending flange 15 which is spaced from the top surface of the post 7 by a distance equal to or slightly greater than the thickness of the carriage guide 14. Thus, the carriage 10 can slide laterally with respect to the hole 4 along the top of the post 7 in a direction parallel to the rear face of the front plate 1. The distance between the flange 15 and the top surface of the post 7 is approximately equal to the thickness of the carriage guide portion 14 to allow the carriage 10 to slide easily along the top of the post 7.

The cable clamping portion 11 of the carriage 10 is connected to the end wall 9 by means of outrigger 12 which has a side face 13 in contact with the interior face of the upstanding peripheral wall la of the front plate 1. The carriage 10 is further located between the side face 2a of the housing 2 and the upstanding peripheral side wall la by the side face 14a of the carriage abutting side wall 2a of the housing. The edge 13 of the outrigger 12 locates the other side of the carriage 10 against the peripheral side wall la.

It will be seen from the illustrated construction that when the screw 17 is rotated is a clockwise direction, the bevelled undersurface 17a of the head 17 will come into contact with the cam surfaces 20 and the carriage 10 will thus move in the direction of arrow A. As a result, the cable clamping portion 11 will be moved into engagement with a cable (not shown) when inserted in the cable access opening 3 or 4. Rotation of the screw 17 in an anticlockwise direction will release the pressure on the cam surface 20 and the carriage 10 will thus be able to be moved in a direction opposite to arrow A and its gripping pressure on the cable will be released.

The cable clamping system illustrated in Figure 4 operates in the following way. When a cable (not shown) is inserted in the access opening 4, it passes through the carriage 10 in a vertical direction as illustrated in Figure 4 and its free end can then be directed to the interior of the electrical component for connection to the terminal connectors (not shown) of the housing 2. On insertion of the cable in the opening 4, the carriage 10 will be in the position illustrated in Figure 4. However, on rotation of the screw 17 in a clockwise direction, the bevelled undersurface 17a of the screw head 17 comes into contact with the cam surface 20 and moves the carriage 10 to the left in the direction of arrow A.This causes the cable engaging portion to bear against the cable in the opening 4 and pushes its opposite side against the ribs 8a and thereby clamps the cable in posicion.

If a cable is to be inserted into the electrical component using side access opening 3, much the same installation procedure is involved except that the cable (not shown) will be pushed into the electrical component through the opening 3 and it will then pass through the carriage 10 past the vertical ribs 8b, the free end of the cable then being available for connection to the electrical connectors (not shown) in the housing 2. In the same way as has already been described, when the screw 17 is rotated in a clockwise direction, the bevelled undersurface 17a of the screw head 17 comes into contact with the cam surface 20 and moves the carriage 10 to the left in the direction of arrow A with the result that the cable gripping portion 11 pushes the cable (not shown) laterally to the left in the direction of arrow A in such a way that it bears against the vertical ribs 8b.

Once in this clamped position, the cable cannot be removed from the assembly until the screw 17 is rotated anticlockwise thereby releasing the pressure of the bevelled undersurface 17a of its head on the cam surface 20.

The advantage of the arrangement shown in Figure 4 is that it is extremely easy for an electrician to operate as it is only necessary for the screw 17 to be rotated to clamp or unclamp a cable inserted in either of the access openings 3 or 4. The carriage 10 is also relatively easy to mold in one-piece so the number of parts for the cable clamping assembly are kept to a minimum.

The main advantages of the preferred cable clamping system of the present invention are that it allows a cable to be inserted in the electrical component to which it is fitted in one of two directions at 900 to each other and yet be clamped using a single clamping element 10.

Thus, electrical components can be manufactured using front plates with front or side cable access openings in them but using the same cable clamping system so manufacturing and assembly costs are substantially reduced. In the prior art, each different design of electrical component needed its own individually designed cable clamping system depending on the location of the cable access opening in the front plate.

It will further be appreciated that the cable clamping systems described and illustrated are very simple to manufacture and assemble and also extremely easy to use as there is only one screw for the electrician to do up to carry out the cable clamping operation irrespective of whether he inserts the cable through a front access opening 4 or a side access opening 3 in the front plate 1. If a spring is used to bias the carriage in the direction of arrow A instead of the screw 17, then the operation of the device is even easier as there is no need for the electrician to bother with a screwdriver other than to push the cable clamping portion 11 of the carriage 10 laterally to one side to allow admission of the cable through the access openings 3 or 4.

Another advantage of the illustrated embodiments is that there is no need to undo anything to insert the cable in the assembly.

Claims

1. An electrical component comprising a front-plate, a housing for the electrical connectors attached to the rear face of said front plate, a cable access opening in the front face and/or peripheral edge of the front plate to provide access for an electric cable to the rear of the front plate, a movable cable clamping member arranged adjacent said cable access opening and shaped to allow a cable inserted in the access opening to pass therethrough in one of at least two different planes, said cable clamping member also including a cable gripping portion and being laterally movable with respect to the cable access opening by moving means arranged so that when a cable is inserted in the cable access opening, the cable passes through the cable clamping member and is gripped by said cable engaging portion of the movable clamping member to prevent withdrawal of the cable from the front plate.

2. An electrical component as claimed in claim 1 wherein the cable passes through the clamping member in two planes.

3. An electrical component as claimed in claim 2 wherein the planes are at 90 to each other.

4. An electrical component as claimed in any preceding claim including a fixed abutment against which the cable is clamped.

5. An electrical component as claimed in any of claims 1-3 wherein the fixed abutment is a projection formed on the housing on the front plate.

6. An electrical component as claimed in any preceding claim wherein the cable gripping portion of the movable clamping member is located at one side of the cable access opening and the fixed abutment is located at the opposite side of said opening.

7. An electrical component as claimed in any preceding claim wherein the cable clamping member is a movable carriage.

8. An electrical component as claimed in claim 7 wherein the cable gripping portion is provided adjacent one end of said carriage.

9. An electrical component as claimed in claim 8 wherein an upstanding projection or end stop extends from the carriage for engagement by the moving means.

10. An electrical component as claimed in claim 9 wherein the moving means is a screw which acts on said upstanding projection.

11. An electrical component as claimed in claim 9 wherein the moving means is a spring which acts on said projection to bias the carriage in a direction whereby the cable gripping means normally grips a cable inserted in either of said cable access openings.

12. An electrical component as claimed in any of claims 1-7 wherein a cam surface projects from the movable carriage for engagement by the moving means.

13. An electrical component as claimed in claim 12 wherein the cam surface protrudes from one end of the carriage.

14. An electrical component as claimed in claim 13 wherein the moving means comprises a screw which engages with the cam surface.

15. An electrical component as claimed in claim 14 wherein the head of the screw has a bevelled undersurface which engages the cam surface.

16. An electrical component as claimed in any of claims 715 wherein the carriage has an aperture therein shaped to allow a cable inserted in said access opening to pass through the carriage past the cable gripping portion.

17. An electrical component as claimed in any of claims 716 wherein an outrigger extends partially around the cable access opening between the cable gripping portion and the remainder of the carriage connected thereto.

18. An electrical component as claimed in claim 17 wherein the outrigger engages the interior face of the peripheral side wall of the front plate.

19. An electrical component as claimed in claim 18 wherein a guide channel or rebate is formed in the side wall to slidingly receive said outrigger.

20. An electrical component as claimed in any of claims 719 wherein the carriage includes a bearing portion slidably supported on the fixed abutment.

21. An electrical component as claimed in claim 20 wherein the bearing portion is located relative to the fixed abutment by a projection formed on the housing or the front plate, the bearing portion sliding between the top of the fixed abutment and said projection.

22. An electrical component as claimed in claim 10 wherein the screw is mounted in a tapped hole in a tab extending from the housing.

23. An electrical component as claimed in claim 10 wherein an earthing strap is fitted to the housing and the screw is mounted in a tapped hole in a tab which is formed as part of said earthing strap.

24. An electrical component as claimed in any preceding claim wherein two sets of cable gripping formations orientated in two directions at 900 to each other are provided on the fixed abutment, the first set being adapted to engage a cable and prevent removal thereof when inserted in the front access opening and the second set being adapted to engage and prevent removal of a cable when inserted in the access opening in the peripheral edge of the front plate.

25. An electrical component as claimed in any preceding claim moulded from a rigid plastics material.

26. An electrical component substantially as herein described with reference to the accompanying drawings.