GB2293499A

GB2293499A - Adjustable cable clamp assembly for connector

Info

Publication number: GB2293499A
Application number: GB9418256A
Authority: GB
Inventors: Lalit Balubhai Makwana
Original assignee: ROXBURGH SWITCHES Ltd; Futters London Ltd
Current assignee: ROXBURGH SWITCHES Ltd; Futters London Ltd
Priority date: 1994-09-09
Filing date: 1994-09-09
Publication date: 1996-03-27
Anticipated expiration: 2014-09-09
Also published as: GB2293499B; GB9418256D0

Abstract

A connector has a collet assembly of adjustable length for clamping cables of different diameters. The connector has an elongate housing 2 through which a cable extends for connection to a connector body 10 which is screwed onto the housing 2 by way of a screw-thread 8. The collet assembly 20 has a number of spaced legs 24 which are movable generally inwardly to grip the cable. The legs 24 are shaped to define a generally conical area 26 which cooperates with an inward taper within the connector housing 2 such that movement of the collet 22 within the connector housing 2 towards a cable passageway 4 urges the legs closer together to clamp the cable. The collet assembly 20 comprises two cooperating elements 22, 40 which enable the length of the collet assembly to be varied. Projections 30 on one element 22 of the collet cooperate with slots 32 in the second element 40. The second element 40 is provided with at least two sets of slots 32 of differing length to provide the length adjustment. <IMAGE>

Description

A CONNECTOR AND AN ADJUSTABLE CABLE CLAMP ASSEMBLY THEREFOR The present invention relates to a connector and to an adjustable cable clamp assembly therefor.

Irrespective of type, connectors for electrical circuits generally require means to clamp the cable to be connected for ease of assembly and to avoid damage to the cable. In elongate connectors, for example, such as DIN connectors, the cable clamp is often a collet of insulating material received within the elongate housing of the connector which is inwardly tapered for cooperation with the collet. As the connector is assembled, the collet, through which the cable extends, is pushed into the housing such that the tapering surface thereof urges the collet to grip the cable.

However, with a collet arrangement it is generally deemed necessary to provide a differently sized collet for each different diameter of cable. This need for collets of different sizes causes problems in manufacturing and problems in use.

The present invention seeks to reduce some of the problems associated with current cable clamp assemblies.

According to a first aspect of the present invention there is provided an adjustable cable clamp assembly for a connector, said cable clamp assembly comprising an elongate tubular member longitudinally slit at one end thereof to define a collet having a number of spaced legs movable generally inwardly of the collet to grip a cable, wherein to enable the collet to grip onto cables of differing diameters, the length of said tubular member is adjustable.

As is usual, the collet of a cable clamp assembly of the invention is intended for use with an inwardly tapered connector housing. The length of the tubular member effects its position in the housing and hence whether it is urged inwardly to grip a larger or smaller diameter. Thus, by adjusting the length of the tubular member adequate gripping of cables of different diameters can be provided.

The elongate tubular member may be provided with the required length adjustment in any appropriate manner. For example, the tubular member may be manufactured as a series of interlocked pieces so that one or more pieces can be removed when a shorter length is required for gripping a wide cable. However, such a multi-piece tubular member does have the disadvantage that if elements thereof are discarded to enable a wide cable to be gripped, such discarded elements may no longer be available if it is subsequently required to use the same connector with a cable of smaller diameter.

Thus, while a multi-piece tubular member may be provided within the scope of this application, it is presently preferred that the tubular member comprise two cooperating elements engagable together to give to the resultant tubular member differing lengths.

In one embodiment of the present invention, the first of the cooperating elements comprises the collet which is removably mounted on a second element comprising an insulation sleeve.

Any suitable engagement between the two cooperating elements enabling adjustment of the length of the tubular member may be provided. For example, the two elements may be telescopically arranged.

In a preferred embodiment, one of said collet and insulation sleeve is provided with one or more projections extending from an end thereof, whilst the other of the insulation sleeve and collet has at least two sets of cooperating slots arranged to receive said projections.

For example, where two projections are provided, two sets each having two slots, with the slots of each set having a different length, may be provided.

Preferably, appropriate guide means are provided on the slots and/or projections of the collet and insulation sleeve to guide the two elements during assembly. For example, a respective channel may be formed along each longitudinal edge of each projection of one element, each channel being arranged to receive the longitudinally extending edge of a respective slot of each set.

In a preferred embodiment, the slots are provided in the insulation sleeve and the projections are formed on the collet.

If the projections of the collet are received in shallow slots in the insulation sleeve there will be a gap between the two elements in the assembled position. A protrusion is preferably provided at the closed end of each shallow slot to prevent collet collapse during assembly.

The present invention also extends to a connector comprising an adjustable cable clamp assembly as defined above.

According to a further aspect of the present invention there is provided a connector comprising a hollow, elongate connector housing open at each of its ends, one said open end defining a cable passageway, a connector body receivable within the opposite open end of the connector housing, and an adjustable cable clamp assembly received within said connector housing, wherein said cable clamp assembly comprises an elongate tubular member longitudinally slit at one end thereof to define a collet having a number of spaced legs movable generally inwardly of the collet to grip a cable, wherein said connector housing is inwardly tapered towards the cable passageway to cooperate with said collet to grip a cable, and wherein to enable the collet to grip onto cables of differing diameters, the length of said tubular member is adjustable whereby the longitudinal position of the collet relative to said tapered connector housing is variable.

A connector of the invention having an adjustable cable clamp assembly may be of any type. Preferably, the connector housing is provided with an internal screw thread at its open end opposed to the cable passageway which is engagable with a corresponding screw thread of the connector body. Of course, the connector body may be of any suitable construction and may be in one or a number of pieces. In a presently preferred embodiment, the connector is a jack plug. In this case, the connector body comprises a jack stem, an externally screw threaded portion for engagement with the connector housing, and terminals for connection to wires of the cable.

The elongate tubular member may be provided with the required length adjustment in any appropriate manner. For example, the tubular member may be manufactured as a series of interlocked pieces so that one or more pieces can be removed when a shorter length is required for gripping a wide cable.

It is preferred that the tubular member comprise two cooperating elements engagable together to give to the resultant tubular member differing lengths.

Preferably, appropriate guide means are provided on the slots and/or projections of the collet and insulation sleeve to guide the two elements together. For example, a respective channel may be formed along each longitudinal edge of each projection of one element, and arranged to receive the longitudinally extending edge of a respective slot of each set.

In an embodiment, anti-rotation means are preferably provided to prevent rotation of said cable clamp assembly within said connector housing. For example, projections on said clamp assembly or on said connector housing or connector body may be provided and arranged to engage with recesses in said connector housing or connector body or in said clamp assembly.

Preferably projections on said clamp assembly are arranged to engage in recesses in said connector body.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an exploded perspective view of a jack plug connector, Figure 2a shows the mutual relationship of elements of a collet assembly of the connector of Figure 1 where a narrow diameter cable is to be accommodated, and Figure 2b shows the relationship of the elements of the collet assembly of Figure 2a when arranged for the accommodation of a cable of wider diameter.

The present invention is illustrated and described below with specific reference to a jack plug connector.

However, the invention is not limited to jack plug connectors and may be used in respect of any other connectors for electrical circuits.

The jack plug connector shown in Figure 1 comprises a hollow, elongate connector housing 2. This housing has an open end 4 which defines a passageway for a cable (not shown). The other end 6 of the housing 2 is also open and is arranged to receive therein a connector body 10. This connector body 10 has an externally threaded portion 8 which is engagable with an internal thread (not visible) formed internally of the connector housing 2 adjacent its end 6. In the embodiment illustrated an elongate hollow coil spring 12 is provided to guide and protect the cable.

This coil spring 12 is inserted through the connector housing 2 to extend from its cable passageway 4.

The connector body 10 comprises a jack stem 14 which is connected with the screw threaded portion 8 by way of a knurled end plate 16. Preferably, the jack stem 14 is made in one piece with the knurled end plate 16 and the threaded portion 8. An insulating body (not visible) is received within the threaded portion 8 and mounts terminals 18 which are to be connected to wires of the cable.

It will be appreciated that, in use, a cable is threaded through the extending coil spring 12 and the cable passageway 4 to extend within the housing 2 such that one end thereof can be connected to the terminals 18 of the connector body 10. Once the necessary electrical connections have been made, the terminals 18 of the connector body 10 are engaged within the connector housing 2 and the threaded portion 8 of the body 10 is engaged with the internal thread of the housing 2.

In known manner it is required to additionally provide within the housing 2 a collet assembly 20 to grip the cable. In the illustrated embodiment of the invention, the collet assembly 20 is generally tubular and comprises two cooperating elements arranged such that the length of the collet assembly is adjustable.

The collet assembly 20 is made of insulating material, such as a plastics material, and a first element thereof comprises a collet 22 which is longitudinally slit to define a number of spaced legs 24 which are movable generally inwardly of the collet to grip a cable. In this respect, and as is conventional, the legs 24 are provided with serrations (not shown) or other surface effects on their inner surfaces to assist in gripping the cable.

Furthermore, the legs 24 are shaped at their outer end to define a generally conical area 26 to assist in the gripping operation of the collet 22.

The inner surface of the connector housing 2, at least at its end portion adjacent to the cable passageway 4, is inwardly tapered towards the cable passageway 4. It will therefore be appreciated that, if the collet 22 is moved within the connector housing 2 towards the cable passageway 4, the legs 24 thereof will be urged closer and closer together. Thus, the nearer is the conical area 26 of the collet 22 to the cable passageway 4, the smaller is the diameter of the cable the collet will be able to grip.

The collet 22 has, at its end opposed to the conical area 26, two diametrically opposed projections 30. These projections 30 are arranged to co-operate with slots, as 32, in the second element 40 of the collet assembly 20. In the embodiment illustrated, the second element is an elongate hollow insulation sleeve 40 provided in its end facing the collet 22 with two sets of diametrically opposed slots 32. As is apparent from Figures 2a and 2b, one set of slots 32' have a relatively restricted longitudinal length whilst, as shown in Figure 2b, the slots 32" of the second set have a much longer length.In fact, the length of the deep slots 32" is substantially the same as the length of the projections 30 such that in the mutual relationship illustrated in Figure 2b, the collet 22 and the insulation sleeve 40 can be engaged by interengagement of the projections 30 and slots 32" such that the facing ends of the two elements abut.

Accordingly, it will be apparent that the collet 22 and insulation sleeve 40 are engaged in a selected one of the two relative positions as illustrated in Figures 2a and 2b in dependence upon the thickness of the cable, indicated at 50. Thus, where the cable 50 has a narrow diameter, as illustrated in Figure 2a, the projections 30 engage in the shallow slots 32' so that the tubular collet assembly 20 has its longest possible length. Where the cable 50 has a wider diameter, as indicated in Figure 2b, the projections 30 engage in the deeper slots 32" so that the collet assembly 20 is much more restricted in length.

To provide for positive engagement between the collet 22 and the insulation sleeve 40, the two longitudinally extending edges of each projection 30 are preferably arranged to define a longitudinally extending channel (not visible) along which the corresponding edge of each slot 32' or 32" can be guided. In addition, at the base of each short slot 32' there is provided a protrusion (not visible) over which the projections 30 sit when the collet 22 is positioned as shown in Figure 2a. These protrusions urge the longitudinal channels of the projections 30 against the edges of the slot and prevent collapse of the collet assembly 20 during assembly of the jack plug connector.

At its end opposed to that in which the slots 32 open, the insulation sleeve 40 is provided with two diametrically opposed projecting pegs 42. These pegs 42 are arranged, on assembly of the connector, to engage within slots (not shown) provided in the threaded portion 8 of the connector body 10. The pegs 42 prevent rotation of the collet assembly 20 and thereby stop the collet assembly from rotating and twisting the cable during assembly of the connector.

Although, in the embodiment illustrated the collet assembly 20 has only two different positions it is able to accommodate a large range of cable diameters. For example, the shallow slots 32' enable the collet assembly to grip cables having diameters in the range 3.3 mm to 4.3mm, whilst the deeper slots 32" enable grip of cables having diameters in the range 4.3mm to 6mm.

It will be appreciated that variations and modifications may be made to the embodiments as particularly described and illustrated above within the scope of the present application.

Claims

1. An adjustable cable clamp assembly for a connector, said cable clamp assembly comprising an elongate tubular member longitudinally slit at one end thereof to define a collet having a number of spaced legs movable generally inwardly of the collect to grip a cable, wherein to enable the collet to grip onto cables of differing diameters, the length of said tubular member is adjustable.

2. An adjustable cable clamp assembly as claimed in Claim 1, wherein said tubular member is formed as a series of interlocked, releasable, pieces.

3. An adjustable cable clamp assembly as claimed in Claim 1, wherein said tubular member comprise two cooperating elements engagable together to give to the resultant tubular member differing lengths.

4. An adjustable cable clamp assembly as claimed in Claim 3, wherein the first of the cooperating elements comprises the collet which is removably mounted on a second element comprising an insulation sleeve.

5. An adjustable cable clamp as claimed in Claim 4, wherein one of said collet and insulation sleeve is provided with one or more projections extending from an end thereof, whilst the other of the insulation sleeve and collet has at least two sets of cooperating slots arranged to receive said projections, and wherein the slots of each set have a different length.

6. An adjustable cable clamp as claimed in Claim 5, wherein guide means are provided on the slots and/or projections of the collet and insulation sleeve to guide the two elements during assembly.

7. An adjustable cable clamp as claimed in Claim 6, wherein a respective channel is formed along each longitudinal edge of each projection of one element, each channel being arranged to receive the longitudinally extending edge of a respective slot of each set.

8. An adjustable cable clamp as claimed in any of Claims 5 to 7, wherein the slots are provided in the insulation sleeve and the projections are formed on the collet.

9. An adjustable cable clamp as claimed in Claim 8, wherein a protrusion is provided at the closed end of each slot of the shallower set to prevent collet collapse during assembly.

10. A connector comprising an adjustable cable clamp assembly as claimed in any preceding claim.

11. A connector comprising a hollow, elongate connector housing open at each of its ends, one said open end defining a cable passageway, a connector body receivable within the opposite open end of the connector housing, and an adjustable cable clamp assembly received within said connector housing, wherein said cable clamp assembly comprises an elongate tubular member longitudinally slit at one end thereof to define a collet having a number of spaced legs movable generally inwardly of the collet to grip a cable, wherein said connector housing is inwardly tapered towards the cable passageway to cooperate with said collet to grip a cable, and wherein to enable the collet to grip onto cables of differing diameters, the length of said tubular member is adjustable whereby the longitudinal position of the collet relative to said tapered connector housing is variable.

12. A connector as claimed in Claim 11, wherein the connector housing is provided with an internal screw thread at its open end opposed to the cable passageway which is engagable with a corresponding screw thread of the connector body.

13. A connector as claimed in Claim 11 or Claim 12, configured as a jack plug, and wherein the connector body comprises a jack stem, an external screw threaded portion for engagement with the connector housing, and terminals for connection to wires of the cable.

14. A connector as claimed in any of Claims 11 to 13, wherein the tubular member comprises two cooperating elements engagable together to give to the resultant tubular member differing lengths.

15. A connector as claimed in Claim 14, wherein the first of the cooperating elements comprises the collet which is removably mounted on a second element comprising an insulation sleeve.

16. A connector as claimed in Claim 15, wherein one of said collect and insulation sleeve is provided with one or more projections extending from an end thereof, whilst the other of the insulation sleeve and collet has at least two sets of cooperating slots arranged to receive said projections, wherein the slots of each set have a different length.

17. A connector as claimed in Claim 16, wherein guide means are provided on the slots and/or projections of the collet and insulation sleeve to guide the two elements together.

18. A connector as claimed in Claim 17, wherein a respective channel is formed along each longitudinal edge of each projection of one element, and arranged to receive the longitudinally extending edge of a respective slot of each set.

19. A connector as claimed in any of Claims 16 to 18, wherein the slots are provided in the insulation sleeve and the projections are formed on the collet.

20. A connector as claimed in Claim 19, wherein a protrusion is provided at the closed end of each slot of the shallower set to prevent collet collapse during assembly.

21. A connector as claimed in any of Claims 11 to 20, further comprising anti-rotation means provided to prevent rotation of said cable clamp assembly within said connector housing.

22. A connector as claimed in Claim 21, wherein said antirotation means comprises projections on said clamp assembly or on said connector housing or connector body arranged to engage with recesses in said connector housing or connector body or in said clamp assembly.

23. An adjustable cable clamp assembly substantially as hereinbefore described with reference to the accompanying drawings.

24. A connector substantially as hereinbefore described with reference to the accompanying drawings.