GB2161994A

GB2161994A - Insulation displacement connector assembly

Info

Publication number: GB2161994A
Application number: GB08415679A
Authority: GB
Inventors: Antony Brasher Clewes
Original assignee: TRW Connectors Ltd
Current assignee: TRW Connectors Ltd
Priority date: 1984-06-20
Filing date: 1984-06-20
Publication date: 1986-01-22
Also published as: GB2161994B; GB8415679D0

Abstract

An insulation displacement connector comprises a housing (12) having two generally parallel side walls and two opposed end walls (22,24) and a cover (14) which is saddle-shaped and is configured to fit over the side walls wherein the end walls (22,24) of the housing (12) extend beyond the side walls so as to prevent sliding of the cover (14) longitudinally of the side walls. A contact member (16) attached to the cover is provided with a formation (90,92) configured to bite into a wall (55) within the housing thereby to position the cover in the open and closed positions. <IMAGE>

Description

SPECIFICATION Insulation displacement connector The present invention relates to an insulation displacement connector of the type suitable for connecting, for example, telephone wires.

For the purposes of this specification, an insulation displacement connector is defined to comprise a housing and a cover, both made of electrically insulative material, and a contact member made of electrically conductive material and engaged with the cover, the housing having channel means configured to receive at least two electrical cables each comprising an insulative covering and wherein the cover is engageable on the housing in an open position in which the contact member does not interfere with cables disposed in said channels and is movable under pressure, relative to the housing, to a closed position in which the contact member severs the insulative covering of the cables in the channels thereby electrically connecting the two cables.

It is known to provide the contact member with two slots aligned transversely of cable length and configured so that when the contact member is moved to the closed position the slots are pressed onto the cables and sever the insulative covering on the cables thereby electrically connecting the conductors in the cables.

It is also known to provide a second pair of slightly wider slots, spaced from and aligned with the first pair of slots and nearer the opening of the channel means which are configured to bite into the insulative material when the contact member is moved to the closed position but act primarily as strain reliefs so that any tension subsequently applied to the cables does not affect their location or cause intermittancy in electrical connection.

It is known to hold the cover in an open position on the housing by providing an interengaging rib and groove arrangement on these two respective parts arranged so that pressure may be exerted on the cover to cause the rib and groove arrangement to disengage thus allowing the cover to move to the closed position. A disadvantage of this design is that increased wall thicknesses are needed to accommodate the rib/groove arrangement leading to a consequential increase in the overall size of the connector. The size of an insulation displacement connector is critical because very often a large number of connectors need to be accommodated in a confined space. Therefore, this is a serious disadvantage.

Also, the use of ribs and grooves tends to permit some play in the closed position which can loosen the electrical connection and cause intermittent malfunction.

It is also know to provide the cover with depending lugs which are configured as a friction fit in the housing to hold the cover in the open poSition. Pressure exerted on the cover causes the lugs to be pushed into the housing. A disadvantage of this design is that the lugs on the cover need to be accommodated within the housing thus increasing the size of the housing and the amount of material used in the connector.

According to the present invention there is provided an insulation displacement connector wherein the contact member is provided with a formation configured to bite into a wall within the housing thereby to position the cover in the open and closed positions.

An advantage of the invention is that no increase in the thickness of the walls of the housing nor of the cover is required in order to provide means for holding the cover in the open position relative to the housing. This enables the overall size of the connector advantageously to be reduced without any consequent loss in the structural strength of the connector. Furthermore, the formations bite into the housing wall to ensure a secure closed position thus maintaining reliable electrical contact.

Preferably, the formation is in the form of a spur provided on an end edge of the contact member. The spur may be barbed so as to facilitate movement of the cover towards the closed position so as to inhibit movement of the cover away from the closed position. In a particular embodiment, the contact member is generally channel-shaped with generally Ushaped edges and both legs of each U-shaped edge comprise at least one spur. Each leg of the contact member may have end edge portions defining spaced upper and lower spurs.

Each spur terminates in an end edge portion which is parallel to the wall. The biting surface of the upper spur may be appreciably greater than the biting surface of the lower spur so that the connector may be designed so that, in the open position, the lower spur retains the cover on the housing.

The housing and cover are normally made of a plastics material and the contact member may be of plated phosphor bronze.

Insulation displacement connectors are known in which the cover is in the form of a box lid and surrounds the housing when the connector is in the closed position. In other known forms of insulation displacement connector the cover is in the form of a lid having a continuous rim which is received within the housing when the connector is in the closed position.

According to a second aspect of the present invention, there is provided an insulation displacement connector wherein the housing has a base, two generally parallel side walls and two opposed end walls and the cover is saddle-shaped and is configured to fit over the side walls and means are provided to prevent the cover sliding longitudinally of the side walls wherein the end walls of the housing extend beyond the side walls so as to prevent sliding of the cover longitudinally of the side walls.

The use of a saddle-shaped cover reduces the amount of material needed in the cover and also enables the overall size of the connector to be reduced as compared with the known designs discussed above.

Preferably, the end walls of the housing extend both laterally and upwardly beyond the side walls. In a particular embodiment, the saddle-shape of the cover fills the region defined by the overlap of the end walls with the side walls thereby to form a compact closed structure in the closed position.

Optionally, the cover comprises a transversely extending depending flange.

Optionally, a ledge is provided adjacent each end wall and extending transversely of the side walls to constitute an abutment surface defining the closed position for the depending flange provided on the cover. This arrangement provides a positive abutment for the cover when it is pressed fully home into the closed position. Preferably, the level of the ledge is below the uppermost extent of the side walls.

The cover may comprise two depending flanges configured to co-operate with two ledges provided in the housing.

A particular embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: FIGURE 1 is an exploded perspective view of a connector according to the present invention; FIGURE 2 is a side view in cross-section (and showing the contact member and cable in elevation) along lines ll-ll of Figure 1 and along direction A showing the connector in the open position; FIGURE 3 is a perspective view of the connector in the closed position; FIGURE 4 is a side view from direction B of the connector shown in Figure 3; FIGURE 5 is an end view along direction C of the connector as shown in Figure 4; FIGURE 6 is an underneath plan view of the connector as shown in Figure 3-5;; FIGURE 7 is a lengthwise cross-section along line ll-ll of Figure 1 of the connector in the closed position (showing the contact member and a cable in elevation); FIGURE 8 is an end view in cross-section along lines VIII-VIII in Figure 7.

Referring to the drawings, an insulation displacement connector indicated generally at 10 comprises a housing 1 2 made of a clear plastics material, a cover 1 4 made of a coloured plastics material and a contact member 1 6 made of plated phosphor bronze.

The housing 1 2 is open topped and has two side walls 18 and 20, two upstanding end walls 22 and 24 and a base 25. Three spaced blocks 26, 28 and 30 extend transversely between the side walls 1 8 and 20. The spaces 27 and 29 between the blocks 26, 28 and 30 are configured to receive legs of the contact member 1 6 when the connector 10 is in the closed position.

The base wall 25 is provided with two transversely extending slots 32 and 34 (see Figure 2) configured to receive legs of the contact member 1 6 when the connector 10 is in the closed position. The slots 32 and 34 are disposed centrally of the spaces 27 and 29 and are each approximately half the width of the spaces 27 and 29.

Each of the blocks 26, 28 and 30 comprises two parallel bores which, together with two apertures 36 and 38 provided in the end wall 22, define two parallel cable-receiving channels 40 and 42 extending through the housing 1 2. The channels 40 and 42 are blind being closed by the end wall 24. Figures 2, 5 and 7 show that the channels 36 and 38 terminate in an indentation 44 provided in the end wall 24 and formed with a cross 45. The crosses 45 are visible through the end wall 24 (see Figure 5) and are visual indications to the user that the apertures 36 and 38 are at the opposite end of the connector 10.

The apertures 32 and 34 each have a chamfered lead-in surface 46 to act as a guideway when a cable is being inserted into one of the channels 40 and 42.

The end walls 22 and 24 extend both laterally and vertically upwardly beyond the side walls 1 8 and 20. The side walls 1 8 and 20 are each stepped at both ends to form ledges 48 and 50 adjacent the end walls 22 and 24 respectively (see Figures 2 and 7).

The side walls 1 8 and 20 each have a rounded upper edge 52 and have relatively thick wall portions 54 and 56 adjacent the blocks 26 and 30 and a relatively thin wall portion 55 intermediate the portions 54 and 56. The thin wall portions 55 provide an interior width in the housing 1 2 sufficient to allow the contact member 1 6 to be received in the housing 1 2. The thicker wall portions 54 and 56 serve to strengthen the side walls 1 8 and 20 of the housing 1 2 and to prevent bowing of the walls 1 8 and 20 during insertion of the contact member 1 6.

A rectangular end block 58 is provided integrally with the end wall 24 primarily as a tactile indication to the user that the apertures 36 and 38 are at the opposite end of the connector 1 0. The block 58 also serves to strengthen the end wall 24 adjacent the internal indentation 44.

The cover 1 4 is saddle-shaped comprising a top wall 60 and two side walls 62 and 64.

Two transversely extending flanges 66 and 68 depend from the top wall 60. A recess 70 is provided centrally on the underside of the top wall 60 and an integral plastics stud 72 extends downwardly from the centre of the recess 70. Each of the side walls 62 and 64 has an internal chamfer 74 along its bottom edge and has bevelled corners 76 and 78.

The contact member 1 6 is generally channel-shaped and comprises a top wall 80 and two side walls 82 and 84 each defining two legs 83, 85 and 87, 89 respectively, and terminating in U-shaped flattened end edges 86 and 88. On the lowermost portions of each of the edges 86 and 88 two upwardly inclined spurs 90 and 92 are formed (see Figure 1). The upper spur 90 has a flattened face 94 which is appreciably larger than the flattened face 96 of the lower spur 92. The lower spur 92 is more sharply upwardly inclined than the upper spur 90.

The side wall 82 has two vertical, strainrelieving slots 98 and 100 each of which is aligned with an opposed, narrower slot 102, 104 formed in the side walls 84. The bottommost edges of the contact member 1 6 are rounded. The top wall 80 comprises a central circular aperture 1 06.

During assembly, the contact member 1 6 is fixed to the cover 14 by cold sealing of the stud 72 after it has been passed through the aperture 106 in the contact member 16. The top wall 80 of the contact member 1 6 transversely fills the recess 70 in the underside of the top wall 60 of the cover 14 (see Figure 8) and this inhibits any rotation of the contact member 1 6 relative to the cover 1 4.

The connector 10 is assembled into the opened position (see Figure 2) by an automatic assembly process which precisely controls the depth to which the cover 14 with the contact member 1 6 attached is pressed onto the housing 1 2. The internal chamfer 74 along the bottom edges of the side walls 62 and 64 of the cover 1 4 ride over the rounded upper edges 52 of the side walls 1 8 and 20 of the housing 1 2 so that the cover 1 4 slides downwardly over the exterior surfaces of the side walls 1 8 and 20.The contact member 1 6 is received within the housing 1 2 and as the cover 14 is pressed onto the housing 12, the lower spurs on the contact member 1 6 bite into the interior surfaces of the side walls 1 8 and 20 of the housing 1 2 and hold the cover 1 4 at the predetermined open position.

As the spurs 92 bite into the side walls 1 8 and 20 of the housing 1 2 the plastics material of the housing 1 2 resiles behind the spurs 92 so that there is no permanent groove formed. The small face 96 of each spur 92 facilitates insertion of the contact member 1 6 to the open position and the upward inclination of the spurs 92 inhibits separation of the contact member 1 6 from the housing 1 2. The upper spurs 90 also dig into the side walls 1 8 and 20 as the cover 14 is being moved to the open position but travel only to a relatively small depth in the housing 1 2 at that stage and so not play an important role when the connector 10 is in the open position.

A predetermined quantity of water-resistant grease is then injected into the connector 10 through apertures 36 and 38 in the housing 1 2 to ensure that ambient water subsequently has no adverse effect on the electrical joint made in the connector 1 0.

In the open position (see Figure 2) the legs 83, 85, 87 and 89 of the contact member 16 are completely clear of the channels 40 and 42 to enable two cables 108 and 110 to be inserted in the apertures 36 and 38 in the housing 1 2 and slide along the channels 40 and 42 until engaging the indentations 44 in the end wall 24 of the housing 1 2. The cables 108 and 110 comprise an electrical conductor 11 2 surrounded by an insulative covering 114.

The electrical conductors 11 2 of the cables 108 and 110 are connected electrically when the connector 10 is moved to the closed position as shown in Figures 7 and 8. The closed position may be achieved by manually applying a predetermined pressure to the cover 1 4 to press it down onto the housing 1 2 or by using a pair of parallel-action pliers or a hand tool specially designed for this purpose.

As the cover 1 4 and contact member 1 6 are moved from the open position towards the closed position, the spurs 90 and 92 on the contact member 1 6 ride down along the interior of the side walls 1 8 and 20 of the housing 12, biting into the side walls 1 8 and 20 as they move, until the flanges 66 and 68 of the cover 1 4 abut the ledges 48 and 50 on the housing 1 2 and the legs 83, 85, 87 and 89 of the contact member locate in the slots 32 and 34 in the base 25 of the housing 1 2 as shown in Figure 8. The upward inclination of the spurs facilitates downward movement of the cover 1 4 but inhibits upward movement.The larger faces 94 of the upper spurs 90 ensure secure retention of the contact member 1 6 in the housing. Both the spurs 90 and the spurs 92 bite into the walls 1 8 and 20 during descent of the contact member 1 6 and the plastics material of the housing 1 2 resiles behind them so that the cover 1 4 is securely retained in the closed position. The provision of two aligned spurs 90 and 92 reduces the likelihood of tilting of the contact member 1 6 and cover 1 4 as they are being moved relative to one another. During descent, the side edges of the slots 102 and 104 in the contact member 1 6 pierce the insulative covering 114 on the cables 108 and 110 and partially bite into the electrical conductors 11 2 thereby electrically connecting these conductors.

The contact member 1 6 is made of material which is substantially stronger than the insula tive material 114 and the electrical conductors 11 2 and therefore does not undergo deformation during descent into the closed position.

As is shown clearly in Figures 3-6, when a connector 10 is in the closed position it is in the form of a compact rectangular enclosure.

The saddleshape of the cover 14 fits neatly in the region defined by the overlap of the end walls 22 and 24 with the side walls 1 8 and 20 of the housing 1 2.

As can be seen from Figures 7 and 8, the electrical conductors 11 2 of the cables 108 and 110 are somewhat compressed within the slots 102 and 104 of the contact member 16 when the connector 10 is in the closed position thus increasing the area of surface contact between the conductors 11 2 and the contact members 1 6.

The strain relief slots 98 and 100 bite into the insulative coverings 114 and touch the conductors 11 2 without biting deeply into them. The slots 98 and 100 are closer to the apertures 36 and 38 defining the openings of the cable-receiving channels 40 and 42 and serve to take up any tension acting on the cables after joining thereby reducing the risk of intermittancy in the electrical connection.

The cover 1 4 and the contact member 1 6 are held in place on the housing 1 2 in a closed position by virtue of the friction gripping on the cables 108 and 110 and the embedding of the spurs 90 and 92 of the contact member 1 6 in the side walls 1 8 and 20 of the housing 1 2.

The amount of grease injected into the connector 10 is calculated so that the cavities in the connector 10 are filled when the connector 10 is in the closed position but so that no grease exudes from the connector 10 as it is moved into the closed position. In particular, grease is present in the spaces 27 and 29 surrounding the area of contact between the contact member 1 6 with the electrical conductors 112 of the cables 108 and 110.

In the particular connector 10 shown above, the housing 1 2 is of clear plastics material and the cover 14 is of coloured plastics material thus providing a clear visual indication of when the cover 14 is fully home in the closed position.

Figure 7 illustrates that clearance is provided between the centre block 28 in the housing 1 2 and the top wall 80 of the contact member 1 6 in the closed position to accommodate the stud 72 with some clearance to allow for tolerance in the size of the stud 72.

A connector according to the present invention is suitable for use with electrical conductors made of copper or of aluminum. It has been found advantageous to plate the phosphor bronze contact member to enhance its ability to maintain contact with the electrical conductors under all environmental conditions.

The insulation displacement connector of the present invention has features described above which enable it to be particularly compact and therefore particularly suitable in situations where a large number of connectors need to be confined in a small space, for example, in connecting telephone lines. It is envisaged to provide more than two cablereceiving channels if desired and, in particular, a three-channel connector is envisaged.

Claims

1. An insulation displacement connector wherein the contact member is provided with a formation configured to bite into a wall within the housing thereby to position the cover in the open and closed positions.

2. A connector according to claim 1 wherein the formation is a spur provided on an end edge of the contact member.

3. A connector according to claim 1 or claim 2 wherein the spur is barbed so as to facilitate movement of the cover towards the closed position but so as to inhibit movement of the cover away from the closed position.

4. A connector according to any preceding claim wherein the contact member is generally channel-shaped with generally U-shaped edges and both legs of each U-shaped edge comprise at least one spur.

5. A connector according to claim 4 wherein each leg of the contact member has end edge portions defining spaced upper and lower spurs.

6. A connector according to claim 5 wherein each spur terminates in an end edge portion which is parallel to the wall.

7. A connector according to claim 5 or claim 6 wherein the biting surface of the upper spur is appreciably greater than the biting surface of the lower spur.

8. A connector according to claim 7 in the open position and with the cover retained by the lower spur.

9. An insulation displacement connector wherein the housing has two generally parallel side walls and two opposed end walls and the cover is saddle-shaped and is configured to fit over the side walls wherein the end walls of the housing extend beyond the side walls so as to prevent sliding of the cover longitudinally of the side walls.

10. A connector according to claim 9 wherein the end walls of the housing extend both laterally and upwardly beyond the side walls.

11. A connector according to claim 10 wherein the saddle-shape of the cover fills the region defined by the overlap of the end walls with the side walls thereby to form a compact closed structure in the closed position.

1 2. A connector according to any of claims 9-11 wherein the cover comprises a transversely extending depending flange.

1 3. A connector according to claim 1 2 wherein the housing comprises a ledge provided adjacent an end wall and extending transversely of the side walls to constitute an abutment surface defining the closed position for the depending flange.

14. A connector according to claim 1 3 wherein the ledge is positioned below the uppermost extent of the side walls.

1 5. A connector as claimed in any of claims 12-14 wherein the cover comprises two depending flanges configured to co-operate with two ledges provided in the housing.

1 6. A connector according to any of claims 1-8 and in accordance with any of claims 915.

1 7. A connector according to any preceding claim wherein the side walls of the housing comprise relatively thin portions aligned with the contact member.

1 8. A connector substantially as herein described and with reference to the accompanying drawings.