EP1407518A1

EP1407518A1 - Cord clamp

Info

Publication number: EP1407518A1
Application number: EP02751315A
Authority: EP
Inventors: Dunford Carl
Original assignee: Delta Electrical Ltd
Current assignee: Eaton Electric Ltd
Priority date: 2001-07-19
Filing date: 2002-07-16
Publication date: 2004-04-14
Also published as: WO2003009428A1; BG108580A; CN100536247C; BG65730B1; CN1543695A; ZA200401039B

Abstract

A cable grip for an electrical appliance comprising a cable entry path having a first, fixed abutment member on one side of the path, and a second, flexible arm member on the opposite side of the path, which is provided with an adjustable clamping means, to urge it in a direction towards the fixed member, so as to clamp a cable between them.

Description

"Cord Clamp"

This invention relates to electrical cable or cord grip devices for mains plugs, sockets, or other electrical appliances, and in particular, to a clamping device which is capable of securely gripping cables of different diameters.

Various types of cable clamping devices have been proposed previously, in order to facilitate the wiring of electrical appliances and particularly, in order to make it easier to insert a wire into a cord grip, whilst holding it securely against subsequent removal. A number of such prior devices depend upon the use of flexible arms, positioned on one or both sides of the cable entry point, and typically, at least one of these arms extends inwardly, i.e. towards the interior of the plug, and has a toothed surface which engages the cord, in order to resist any outwardly directed pull. However, such devices commonly have the shortcoming that depending upon the opening size of the entry point, they can only be used with a limited range of cable sizes, and they are not as secure as devices incorporating clamping screws.

Accordingly, the present invention seeks to provide a cord grip which is capable of securely clamping cables having a wide range of diameters, whilst still allowing them to be easily inserted into the plug for assembly purposes.

Accordingly, the present invention provides a cord grip for an electrical appliance comprising a cable entry path having a first, fixed abutment member on one side of the path, and a second, flexible arm member on the opposite side of the path, which is provided with an adjustable clamping means, to urge it in a direction towards the fixed member, so as to clamp a cable between them.

Preferably, the flexible member comprises an arm which extends generally parallel to the path of the cable, and has one end fixed in the appliance, whilst the other end is free, but can be engaged by a clamping screw, to urge it towards the fixed member. In a preferred embodiment of the invention, the fixed member has a ridged or stepped surface, with the ridges extending at right angles to the path of the cable, whilst the flexible member has a ridged or stepped surface on which the ridges or steps extend parallel to the path of the cable In the way, it is possible to ensure that the cable is not only held securely against being pulled directly out of the plug or appliance, or pushed in, but is also secured against twisting, which could otherwise cause the conductors to become detached from their terminals

Alternatively the ridges may be provided on the flexible member and the steps on the fixed member, or one or both members may carry an arrangement of steps each of which has a surface which is also transversely ridged

One embodiment of the invention will now be described by way of example, with reference to the accompanying drawing, in which

Figures 1 to 5 are examples of various known types of electrical cord grips, Figure 6 is a plan view of a cord grip arrangement according to the present invention,

Figure 7 is a cross-section taken on the line A-A of Figure 6, Figure 8 is a perspective view of the cord grip of Figure 6 and 7, and Figure 9 is a partial perspective view of an alternative embodiment of the invention Referring firstly to Figures 1 to 5, which are diagrammatic views of various known types of cord grip designs, it will be seen that these generally fall into two categories the types shown in Figures 1 and 2, in which the cable is clamped into position by means of screws, and the type shown in Figures 3 to 5, in which the clamping effect depends on resilient arms of various configurations In the first type, screws 2 and 4 as shown in Figure 1 are used to tighten a semi-rigid bar 6 down onto the cable 8, to clamp it into the entry channel, while Figure 2 shows an arrangement with a single clamping screw 10 which carries an enlarged head 12, to bear directly on the cable In the alternative types of arrangement, shown in Figures 3 to 5, the cable is typically held in position by means of shaped flexible arms 14, 16 having ridged surfaces 18, 20 These engage the cable in such a way that any attempt to pull the cable out of the C .d grip, in the direction (B) of Figure 3, flexes the arms so as to engage them more tightly with the cable Instead of two arms, there may be a single arm 22 or 24 as shown respectively in Figures 4 and 5, which forces the cable into engagement with an opposed surface 26 or 28 These however do not stop the cable from being pushed in and have limited twisting capabilities

Whilst cord grips of the first type, including screws, have the advantage that they hold the cable very securely, they also have the disadvantage that, in contrast to the grips of the second type, it is usually more difficult to attach and secure the cable, whereas, with the second type, assembly is simpler but, generally speaking, the cable is then not quite so well secured

By contrast, as will be seen from the plan view of Figure 6, the cord grip of the present invention combines the ease of assembly of a "flexible arm" type of clamp, with the security of a screw fixing clamp A fixed abutment member 30 is fitted on one side of the cable entry path, and has a ridged surface 32 facing the adjacent side of the cable 34 The ridges extend at right angles to the direction of the cable entry path, so as to resist any tendency for the cable to be pulled out of the appliance On the opposite side of the cable entry path, a flexible arm 36 extends generally parallel to the path of the cable, with its inner end 38 fixed to the interior of the appliance A clamping screw 40 is threaded into a fixed mounting block 42 in the appliance, and its inner end 44 bears against the outer end of arm 36, so that when the screw is tightened, the outer end of the arm moves to the dashed position 46 indicated in Figure 6, where it engages the side of the cable

As best seen in Figures 7 and 8, the facing surface 48 of the arm 36 carries a stepped formation, with the steps extending parallel to the cable direction, so that when the arm is moved to the engaged position as shown in Figure 6, the upper edge 50 overlaps the cable somewhat, so that the cable is held firmly in position against the opposing ridged surface 32.

It will be appreciated that, in addition to the conventional action of the ridged surface 32 in preventing the cable from being pulled out of the appliance, the stepped back formation 48 of the flexible arm 36 tends to force the cable downwardly into the entry path, as well as laterally against the ridge surface 32. This holds it very securely against any twisting action which could otherwise result in the conductors 52 being detached from the electrical terminals of the appliance. Referring to Figure 9, this illustrates an alternative embodiment in which the end of the flexible arm 36 has a stepped formation (44), in a similar way to the embodiment of Figures 7 and 8, but in addition, the surface carries a series of transverse ridges 46 which extend parallel to the ridges 32 on the opposite, fixed abutment surface (Figure 8). These ridges are so arranged that there is a set of ridges (46) on each of the "steps", extending transversely to the steps, so that the cable is effectively gripped in two directions. Again, this arrangement ensures that in the engaged position of the movable arm 36, the upper steps 44 will partly overlie the cable so as to hold it more firmly, as in the case of the Figure 8 embodiment.

Although the exemplary embodiments show the arm 36 as extending outwardly relative to the cable entry, it could alternatively extend inwardly.

Claims

1. A cable grip for an electrical appliance comprising a cable entry path having a first, fixed abutment member on one side of the path, and a second, flexible arm member on the opposite side of the path, which is provided with an adjustable clamping means, to urge it in a direction towards the fixed member, so as to clamp a cable between them.

2. A cable grip according to claim 1 in which the flexible member comprises an arm which extends generally parallel to the path of the cable, and has one end fixed in the appliance, whilst the other end is free, but can be engaged by a clamping screw, to urge it towards the fixed member.

3. A cable grip according to claim 1 or claim 2 in which the cord grip members are provided with ridged or stepped surfaces for engaging the cable so as to inhibit pulling or twisting of the cable.

4. A cable grip according to claim 1 or claim 2 in which the ridges or steps on one of the members extend at right angles to the path of the cable and the ridges or steps on the other member extend parallel to the path of the cable.

5. A cable grip according to claim 4 in which the ridges or steps extending parallel to the path of the cable are so arranged that the corresponding member partially overlaps the cord when the grip is in the engaged position.

6, A cable grip according to claim 3 in which at least one of the members is formed with a stepped surface on which the steps extend parallel to the path of the cable, and the surface of each step is additionally formed with ridges which extend transversely to the path of the cable.

7. A cable grip according to claim 6 in which the steps are so arranged that the width of the cable entry path varies progressively, from a relatively greater width at the inner side of the path, to a relatively smaller width at the outer side of the path, so that the outer side of the member carrying the steps partially overlaps the cable when the grip is in the engaged position

8 A cord grip according to claim 3 in which the ridges or steps on the fixed mender extend at right angles to the path of the cable, and the ridges or steps on the flexible member extend parallel to the path of the cable

9 A cable grip according to claim 3 in which the ridges or steps on the fixed member extend parallel to the path of the cable, and the ndges or steps on the flexible member extend at right angles to the path of the cable

10 A cable grip according to any preceding claim in which the adjustable clamping means comprises a screw which is threaded into a fixed mounting olock

11 A cable grip substantially as herein described with reference to Figures 6 to 8 of the accompanying drawings