GB2237695A - Cable clamp in electrical connector - Google Patents

Abstract

A connector cable clamp comprises a plurality of hinged blades T, U. The blades are arranged in cooperating pairs, so as to resiliently grip a cable and prevent its withdrawal from the connector. Each blade is formed with a reduced-width section b acting as a hinge and circumferential ridges a to help retain the blade root in the connector body. Blade pairs towards the outside of the body become successively shorter to accommodate larger diameter wires more comfortably. <IMAGE>

Description

13amp. 250v. Electrical Connector The present invention relates to the field of electrical connectors, and in particular to 13amp. 250v. connectors according to BS 1363A though without prejudice to other devices.

There exist in this world a large number of relatively handicapped people - for example, many of our increasingly elderly population. All these people, in general value their independence and this to a large extent revolves around their ability to look after themselves. In everyday life this means being able to perform such mundane tasks as connecting, inserting and withdrawing the standard 13amp three pin 250v electric plug, to connect their kettles, vacuum cleaners, radios and televisions, and so on, to the power supply. The configuration of such plugs is, in this country, largely governed by British Standard 1363A: this, though is admirable in intention, tends largely to preserve the status quo, and like most other standards tends to define past states of the art to which it applies.

In the case of BS1363A, it upholds desirable criteria in terms of insulation and physical requirements, but simultaneously insists upon the retention of antediluvian means of connecting the electric cable into the said plug, by insisting upon the retention of screws.

Such screws are not necessarily essential to the functioning of such a plug, and put the connecting of the same beyond the means of many otherwise quite capable of doing such a job, due to impaired mobility of their hands, these persons also frequently have great trouble in removing or replacing such a plug from the electrical supply socket. Previous efforts to eliminate such uncalled for irritations in connecting and using an electrical plug have included the following different approaches, for example: preconnecting the said electrical cable to a connecting means, usually supplied with a rapid connecting system, and in turn pressing the said means into the body of the said plug.

Whilst this marginally simplifies the operation of connecting the cable it adds greatly to the expense and complication of the whole assembly, ..... the provision of a screwless terminal such that the said electric wires are connected by being entrapped beneath a hinged lid formed upon the connecting means. The said lids are small, and require force to press shut, but nevertheless an advance upon screws, needing less manual dexterity.

..... the provision of insulation piercing conductors eliminating the need for stripping the insulation sleeve from the said wire. Such systems tend to be better suited to factory production lines if reliable results are to be obtained.

..... cable clamping means of varying types. Those best suited to cater for a wide range of cable sizes employ screws to apply pressure, either directly or indirectly. The simplest, if able to grip small cables usually require either modification, or strength, on the part of the user, if they are to fit large cables inserting plugs into, and removing the same from sockets takes a certain amount of force. The fingers of many people are unable to exert such a force, nd in an effort to assist the same some plugs are fitted with a lid means whereon a ring is formed as an extension thereof1 normal to the lower face of the said plug, and lying upon the centreline, as drawn through the earth pin centre and the cable entry point.Such a device is an improvement but requires a strong index finger, since only one finger can be employed for the task, and thus, though an advance upon the present state of the art, one of limited usefulness.

Objects of the present invention are the overcoming of such complexities and disadvantages, in the interests of both those users with impaired mobility and the healthy.

The present invention is outlined in the accompanying figures, in which for clarity's sake the same references refer to the same parts throughout. In figure 1 is seen an elevation upon the right hand side of the plug, in which the connecting pins are seen, E being the earth, L being the live, the Neutral pin being obscured behind the same. At B is the base assembly, the lid thereof at A, and the T shaped handle C lying thereon in the stowed position, the said handle being pivottably mounted thereon. In figure 2 is a plan upon the said plug, showing the said handle in the stowed position. At D may be seen the pivot bearing housing assemblies upon which it rotates, and at F outside the said bearing means D, further bearing and locating means F.The said handle is preferably a one piece moulding, in which the shaft thereof has, at base and head, lateral extensions upon either side, those at the head forming a T shaped bar that may the more easily be gripped, either stowed or in the operative position, and those at the base, lying in the same plane as those at the head, forming the pivoting and locating means upon which the said handle rotates and is held by assemblies D and F.That portion of the said lower lateral extension located in D is of circular cross section, that portion of the said same extension located in F is of circular cross section save that the said circular profile is cut by two chords of the said circle intercepting eachother at such an angle that when one such said flat produced thereby is engaged in a corresponding co-operative flat formed in the said housing F the said handle means is held thereby in the stowed position, and when rooted to bring the same into the operative position the second flat upon the said shaft engages with the aforesaid flat upon the said housing means F to hold the said handle C in the said operative position, the said housing F springing sufficiently to enanble the said rotation to occur.In figure lit will be seen that the said housing F is possessed of open jaws, the said bearing means D being similarly profiled; the said handle C is fitted thereinto by pressing the same into the said jaws, and causing the same to spring sufficiently to accept the said jaws, which being entered thereinto, are subsequently securely held in normal use. The T bar at the head of the said handle enables an impaired user to lift the said handle from the stowed to the operative position with less difficulty than other shapes, and the configuration of the handle employed permits the said plug to retain relatively innocuous profile in the stowed position, making the same safer in use, whilst economising on the use of space in packing and transporting the same in the making and marketing operations.

The spring form requires relatively minor force to shift the handle from one position to the other, and is designed to hold the said handle in position whilst the said user removes the hand employed to bring the same from the stowed position to then operative position, to replace the same to better advantage to insert or remove the said plug into or from a socket.

In figure 3 is a plan upon the underside of the said plug. At L, E, and N may be seen the connector pins. At H may be seen an aperture in the said plug base, communicating with the interior thereof, and isolated from contact, through which the fuse may be seen, and the rating thereof visually checked. Fuse colours and ratings may be displayed in writing upon the underside of the said base. At J is a further aperture, and lying, visible therein1 is a locking lever K, seen in the locked position, which may be seen in elevation in figure 4, which is an elevation upon the left hand side of the plug, in section, upon the plane of r - r in figure 3. The locking lever K is pivotably engaged in an extension of the said plug base. at M.At the left hand end of the said locking lever K a lateral extension P projects outwardly to lock in a corresponding recess in the said plug base B to lock the said plug closed. At the opposite end a hook, whose jaws may be springable, engages upon an extension of the said plug lid A at R. The said plug lid A may be disengaged from the said hooking means Q by moving the said lever laterally by inserting a small lever, for example a screwdriver, into the aperture S and bending the said lever K outwardly, so disengaging the said lateral extension P from it's co-operative point of engagement in the said base B, and moving the said lever K radially about M to disengage the said hooking means Q from the said extension of the lid A, which may now be slidden away from the cable entry point in the plane of the underside of the said plug, base, and lifted off, leaving an assembly as seen in figure 5, in plan, in which may be seen, depicted by dotted lines, upon either side thereof, at 1 & 1, 2 & 2, 3 & 3, the receptors in the said plug base which accept the same therein, upon the lid being fitted, the co-operative corresponding projections shown in figure 6 at 1, 2, and 3.

At the cable entry end of the said plug the said lid engages with the said base B upon mating projections thereof, which slideably engage with the mating receptors, 3 & 3, formed in the end wall of the said lid A. The pull of the handle C is thus evenly transferred to the lid A, and thence to the base B, the said locking lever K acting solely as a locking mechanism and, being some 35mm in length overall, and 25mm from the pivot M to the extremity at P, of a size more easily handled than other locking means. To fit the lid it is located upon the said plug base B and slidden toward the cable entry end, so engaging the said projections upon their respective receptors. The lever K is then rotated about M to bring the hooking means to bear upon the said extension R in the said lid A, and pressed home.The said lever K bends laterally, and outwardly to permit the same to pass the lateral extension P about the said base means B, as seen in a scrap section upon the same, seen in the locked position, in figure 7. Reverting to figure 5: at X, Y, and Z respectively may be seen the neutral earth and live connector assemblies, in the shut position, of which more below. At cf is the cartridge fuse assembly, at T and U the ccFoperative jaws of the cable clamp assembly. The said cable clamping means is formed of a plurality of co-operative paired assemblies, in the preferred embodiment injection moulded, each such assembly being made up of two parts, as seen for example at T and U, which may be seen in greater detail in figure 8, and figure 9 which is an elevation upon the root end of the said blade T in the direction of the arrow V.At "a" may be seen a plurality of extensions of the surface of the said blade T disposed horizontally about the blade root7lie extensions formed upon the surface of the next blade adjacent to the said T, namely U, and upon any further plurality employed in conjunction therewith being so located that they do not,when the said blades are correctly assembled, interfere with eachother, but lie between eachother fitting alternately. The said extensions are so profiled in section that the underside thereof slopes outwardly and upwardly, as shown, to the apex of the said extension, the upper side whereof forms upon it's upper side, an included angle with the surface of the said blade not greater than 90 degrees.The said extensions serve two purposes: firstly to take up manufacturing tolerances in the said blades and the said root housing means, and secondly to ensure that the said blade means is press fitted into the said root housing, as a collective unit of such plurality as is employed, and locked thereinto by the bias of the said extensions "a", and are thus unable to drop out when the said plug, the lid having been removed for whatever reason, is inverted for whatever purpose. In configuration the innermost of the said blades, that is that pair seen at T, is the longest, each successive such blade as is employed being shorter than the last, thus U is shorter than T.The said blades Tare located symmetrically about the approximate centre line of the cable entry : earth pin axis, and so placed about the same that the included angle at their tips upon the said centreline, at which point they are contiguous or nearly so, upon the cable entry side thereof, is less than 180 degrees upon the cable entry side. Each such blade is diminished in cross sectional width by a vertical groove, shown by way of example, unilaterally disposed, at "b", the said diminution or plurality thereof being located at that point at which the said blade emerges from the said root housing, or nearly so.The said diminution "b" may be made up of a plurality of such grooves, disposed upon one or both sides, symmetrically or asymmetrically about the same, acting as a hinge means in the said blade about which the same bends in use, bending radially outwards when a cable is pressed between the same, the uppermost side of the said blades being at their free ends, higher than at their root ends, sloping upwardly from the hinge points "b" to their free ends, the said rise making a blade profile easier to introduce the electric cable in between. When the said cable clamped therein is outwardly pulled towards the said cable entry point, the said jaws T gripping the smallest cables likely to be sensibly employed therein, and being by their nature biased to returning to their free state position, outwardly pressed onto the said cable, hold the same, resisting the said pulling force. If this force be increased to the extent that the said blades T are inclined to bend toward the said cable entry point under load the secondary blades take up the load thereon, supporting the first, and any further blade or plurality thereof likewise.

Thus the jaws T are backed up by jaws U and so on. Larger cables are held by both jaws and if large enough, by any further such plurality fitted. Such a configuration is advantageous since the forces required to effect a cable entry remain low whether the said cable be large or small, unlike the conventional blade clamping means, some of which require very considerable force to insert a large cable.

Claims (3)

WHAT WE CLAIM IS:

1.) A cable clamping means wherein a plurality of co-operative pairs of blades, of whatsoever material, standing normal to the plane of the lower face of the plug base assembly, have their root ends securely held therein, the blades being symmetrically disposed about the approximate centreline of the aid cable path, their free ends projecting inwardly toward the said centreline, to form, at their conjunction, in repose, upon the cable entry aperture side thereof, when viewed in plan, an included angle of less than 180 degrees, the free ends of that pair of the said blades located furthest from the said cable entry aperture being contiguous to eachother upon the said cable centreline, or thereabouts, prior to the insertion of the same, the next such pair to it, upon the said cable entry aperture side thereof, being somewhat shorter, and any further plurality so fitted likewise each being shorter than the last such, all the said blades being press fitted into their respective root housings, and sharing the following features in common: 1. A blade root, howsoever configured, wider than the run of the body of the said blade, such that when the said blade, or any co-operative plurality thereof, are properly assembled in the said blade root housing they cannot be withdrawn, save in a vertical direction relative to the plane of the underside of the said plug base.

2. A blade root area over which a plurality of extensions are formed upon the surafce of the said blade root, the said extensions being disposed as horizontal ridges whose lower surfaces may slope upwardly and outwardly from the said surface to the apex of the said extensions, whose upper surfaces, viewed in cross section, form, upon their upper side, an included angle with the surface of the said blade root no greater than 90 degrees, so forming a ridge upon the said surface, and which said ridges are so disposed that upon the contiguous sides of such a plurality of the said blades as may assembled together no such ridges upon the sides of adjacent blades clash together, the said horizontal extensions serving in two capacities: that of preventing the said blades from falling out of their respective root housings upon the said plug base being inverted whilst without the lid thereof, as may happen when being wired or unwired, and for the purpose of absorbing variations in the size thereof due to manufacturing tolerances in both the said blades and the said blade root housings.

3. A cable clamping means wherein the said blades, at that point at which they emerge from their respective blade root housings, or closely adjacent to the same, to project inwardly towards the said cable path centreline, as above described, are diminished in thickness, the said diminution taking the shape of a groove, or a plurality thereof, in one or other, or both of the surfaces as may be required of each such blade, the said groove or plurality thereof being formed in the surface of the said blades and lying normal to the plane of the under side of the said plug baseplate, to form a hinge about which the said blades may advantageously the more easily bend, so to open and accept the said cable betwixt their free ends, and onto which they are continuously pressed by the bending stresses incurred in the material of which they are made as it attempts to return to the original free position in which it was made, and in which such cable clamping means the secondary contiguous blade, and such further plurality thereof as may be employed upon the cable entry aperture side of the first such blade above described, acts in support of that blade before it, such that when the said cable gripped by the first such pair of blades is outwardly pulled from the said plug base, they become the more firmly clamped upon the same, and where the said such cable is of too small a size to be gripped by any further such pair of the said co-operative blades employed, they being too short to reach the said cable, the said such secondary and further blades if employed support the first such pair if it be sufficiently stressed, by preventing the same from turning about their hinges despite the presence of the same, the said configuration of a plurality of hinged blades as described rendering the insertion of both large and small cables into the said cable clamping means easier than is normally the case and providing greater gripping capacity for larger cables, which in general use, are those usually subject to most abuse.