GB2299461A

GB2299461A - Cord grip

Info

Publication number: GB2299461A
Application number: GB9506707A
Authority: GB
Inventors: Terence William Thomas
Original assignee: Caradon MK Electric Ltd
Current assignee: Caradon MK Electric Ltd
Priority date: 1995-03-31
Filing date: 1995-03-31
Publication date: 1996-10-02
Also published as: GB9506707D0

Abstract

A cord grip for locking an electrical cable into an electrical accessory such as a switched flex outlet, the grip comprising a resiliently flexible arm 38 extending from a wall 4 toward an opposite wall 5 and to a free end 7. The arm 38 has at least one tooth 36 on it which acts with the opposite wall 5 to grip the sheath of a cable. One or more stops 34 extends in a space between the walls so that the cable when pushed into the grip is stopped so that it is in tooth engaging position yet not inserted too far into the grip. The arm has an extension 32 to the free end for lifting the arm in direction P off the cable for disconnection from the grip or to assist in inserting the cable. Cable rotation is discouraged by ribs 42 having sharp inner ends. A blanking plug 66 is retained by an extension 70. The grip is trapped in the accessory by means of a grip lug (54, figure 5).

Description

CORD GRIP The present invention relates to a cord grip.

Cord grips of various designs for locking an electrical cable into an electrical accessory such as a plug where the cable needs to be safely secured to the accessory are well known. Commonly, they comprise a strap screwed over a recess in which the cable is fitted. In order to avoid the necessity of using a screwdriver and the possibility of loosing screws, we have designed a vane type cord grip for a plug in which a pair of angled vanes acting as gripping arms, either side of a recess, grip the cable with their inner surfaces.

Where cable is pushed between the inner surfaces of the arms there is nothing to prevent excessive insertion. This can cause strain on the terminals.

A cord grip according to a first aspect of the invention comprises a resiliently flexible arm having a tooth thereon, the arm extending from a wall toward an opposite wall and to a free end so that a cable to be gripped when inserted between the walls is trapped between the tooth of the arm and the opposite wall, and further comprising a stop protruding into a space between the walls.

The stop or there may be a plurality of stops act so that when a cable is pushed between the walls and beyond the tooth or several such teeth it stops the outer sheath of the cable from further intrusion into the grip. That is the cable abuts the stop or stops.

Preferably the arm has an extension on the free end providing a means for digitally lifting the arm off a cable in the grip. The opposite wall preferably has ribs extending parallel with the cable inserting axis of the grip. These ribs help to prevent the cable rolling between the gripping surfaces. The walls may be formed as part of a tubular member.

The tubular member is preferably square so that it can fit into a corner of the front plate of an accessory.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a cross section of a cord grip according to the invention, with an end of a cable shown ready to be inserted into the cord grip, the cross section being taken on line AA of Figure 6; and, Figure 2 shows the same cross section and cable as Fig. 1, but with the cable partially inserted into the cord grip; and, Figure 3 shows the same cross section and cable as Fig. 1, but with the cable fully inserted into the cord grip; and, Figure 4 shows a similar cross section of the cord grip shown Fig. 1, but fitted to a front moulding, with a blanking plug fully inserted into the cord grip so that it closes off the cable entry hole in the front plate; and, Figure 5 shows a side elevation of the cord grip shown in Fig. 1 fitted to a front plate moulding and a rear moulding both of which are sectioned, the cross section being taken on line BB of Fig. 6, so that the means of retention of the cord grip may be seen; and Figure 6 shows a plan elevation of the cord grip and front plate and rear moulding shown in Figure 5 viewed from the rear.

In the drawings a cord grip 2 best shown in Fig. 4 is shown which comprises a square tubular member 3 from the inner surface of one wall 4 of which there extends a flexible arm 38. The arm has thereon three teeth 36. The arm with its teeth extends toward an opposite wall 5 and from its root 6 to a free end 7 which further extends to a thumb pad 32, or means for digitally lifting the arm off a cable 10. The gripping surface of the teeth is castellated as may be seen at 37 in Fig. 6.

The opposite wall 5 has three ribs 42 the function of which will be described below which extend parallel with the cable inserting axis in direction M. The opposite wall 5 also has terminal stop projections or stops 34 the function of which will also be described below.

The cord grip is substantially square in cross section so that it can fit into a corner 50 of the front plate 52 of an electrical accessory such as a switched flex outlet.

The grip is retained at the rear of the front plate by means of a lug 54 which is trapped in a recess 56 of an accessory part 58 and a rib 60 which engages in a corresponding groove in part 58. A flange 62 on the front of the tubular member 3 seats against the rear of the front plate, the flange 62 being curved at 64 so that the grip and part 58 can be inserted into the rear of the front plate in direction Q.

A blanking plug 66 (see Fig. 4) to blank off cable entry hole 68 in the front plate fits into the tubular member and is retained therein by an extension 70 which clips over stops 34.

Figures 1 to 3 show the sequence of inserting a flexible cable 1 into the cord grip 2. The flexible cable 1 has its outer sheath 10 cut back to reveal inner insulation 12, 13, 14. The inner insulation is also removed to expose the conductors 15, 16, 17 to the extent that is required for making electrical connection to the accessory (not shown) that the cord grip is attached to. Figure 2 shows the thumb pad 32 of the cord grip 2 moved by finger or thumb pressure in the direction of arrow P to allow the insertion of the flexible cable 1, which is pushed fully in until the cut end 18 of the outer sheath 10 abuts up against the stops 34. (Stops 34 may be also seen in the plan elevation of Fig. 6.) The pad 32 is then released and the gripping teeth 36 are forced by the resilience of the flexible arm 38 against the outer sheath 10.The force exerted by the flexible arm 38 on the cable 1 also causes the teeth 40 formed by the sharp ends of the anti-rotation ribs 42 to also grip the outer sheath.

Teeth 36 are shaped so that they permit the insertion of the cable in the direction of arrow M, but resist the removal of the cable 1 by a force on the cable in the direction of arrow N. This is beneficial as it allows the force required to be exerted by flexible arm 38 to be reduced to a minimum, which in turn reduces the force a user has to apply to thumb pad 32 to enable the cable to be inserted by pushing in the direction of arrow M. However it is a requirement for some of the accessories that the cord grip may be fitted so that it shall not be possible to force the cable into the accessory once fitted. The reason for this requirement is to prevent strain on the electrical connections made to the conductors 15, 16, 17. Stops 34 ensure that the cable may not be inserted any further once the cut edge of the outer sheath has abutted against them.

Further ribs 42 combined with teeth 36 prevent rotation of the cable about its longitudinal axis. The sharp ends 40 of the ribs 42 by causing locally high pressures on the outer sheath of the cable are pressed into the outer sheath 10 hence improving both the resistance to rotation and the resistance to removal of the cable by a force in the direction of arrow N.

Claims

1. A cord grip comprising a resiliently flexible arm having a tooth thereon, the arm extending from a wall toward an opposite wall and to a free end so that a cable to be gripped when inserted between the walls is trapped between the tooth of the arm and the opposite wall, and further comprising a stop protruding into a space between the walls.

2. A cord grip as claimed in claim 1 wherein the walls are formed as part of a tubular member.

3. A cord grip as claimed in claim 2 wherein the tubular member is substantially square in cross section.

4. A cord grip as claimed in any one of claims 1 to 3 wherein the arm has an extension on the free end providing a means for digitally lifting the arm off a cable in the grip.

5. A cord grip as claimed in any one of claims 1 to 4 wherein the opposite wall has provided thereon ribs on its inner surface, the ribs extending parallel with the cable inserting axis of the grip.

6. A cord grip as claimed in any one of claims 1 to 5 wherein the tooth has a castellated gripping surface.

7. A cord grip as claimed in any one of the preceding claims wherein there is a plurality of said teeth on the arm.

8. A cord grip substantially as described with reference to the accompanying drawings.

8. A cord grip as claimed in any one of the preceding claims wherein there is a plurality of said stops.

9. A cord grip substantially as described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows 1. A cord grip comprising a resiliently flexible arm having a tooth thereon, the arm extending from a wall toward an opposite wall and to a free end so that a cable to be gripped when inserted between the walls is trapped between the tooth of the arm and the opposite wall, and further comprising a stop protruding into a space between the walls wherein the arm has an extension on the free end providing a means for digitally lifting the arm off a cable in the grip.

4. A cord grip as claimed in any one of claims 1 to 3 wherein the opposite wall has provided thereon ribs on its inner surface, the ribs extending parallel with the cable inserting axis of the grip.

5. A cord grip as claimed in any one of claims 1 to 4 wherein the tooth has a castellated gripping surface.

6. A cord grip as claimed in any one of the preceding claims wherein there is a plurality of said teeth on the arm.

7. A cord grip as claimed in any one of the preceding claims wherein there is a plurality of said stops.