WO1997011510A1

WO1997011510A1 - Mechanical connectors

Info

Publication number: WO1997011510A1
Application number: PCT/GB1996/001588
Authority: WO
Inventors: Brian Henry Birkett
Original assignee: Birkett Electric Ltd.
Priority date: 1995-09-22
Filing date: 1996-07-03
Publication date: 1997-03-27
Also published as: HK1001938A1; GB2305549A; GB2305549B; AU6312496A; GB9519385D0

Abstract

A mechanical connector for connecting electrical cables. The connector has a channel shaped housing carrying a loosely retained clamping plate and a support plate slidably mounted between the walls of the channel. The support plate has threaded orifices for receiving clamping bolts or screws of a given length which can be adjusted to bear on the clamping plate to clamp the cables between the clamping plate and the inner wall of the channel housing. The support plate and channel housing have complementary shaped mounting elements which allow the support plate to be inverted in position between the channel walls. The orifice openings are on two opposing faces of the support plate, one of which is closer to the mounting element than the other. Thus the allowable screwable travel of the bolts towards the clamping plate to the shearing tension required is greater in one inverted position of the support plate than the other. Cables of a wider range of size than heretofore possible can thus be clamped between the clamping plate and housing wall of the mechanical connected simply by inverting the support plate to suit and driving the screws through the orifices towards the clamping plate from the opposite face of the support plate.

Description

MECHANICAL CONNECTORS

FIELD OF THE INVENTION

The present mvention relates to mechanical connectors for couplmg electπcal cables or wires.

BACKGROUND OF THE INVENTION

In particular, the present mvention relates to such connectors for use m mams distπbution m an underground location. In such applications, the connector is finally encapsulated in a sealant mateπal electπcally to insulate the connection so formed

A common type of mechamcal connector in present day use is in the form of a U-shaped channel in which two cables to be connected may be assembled The channel has a loosely fitted pressure pad which can be clamped agamst the cables in the channel by means of shear off bolts screw mounted in a bolt suppon plate. The bolt support plate is shdably mounted transversely between the walls of the channel.

Single channel connectors are generally employed in straight through mams connectors where the cables to be connected are of similar size

In some cases integrally formed side by side channel connectors are used to effect the electπcal connection, each channel incorporating pressure pads and tensionmg bolts as descnbed above. Such dual channel connectors have application where, in a mams distπbution network, an uncut mam sector shaped conductor has to be electπcally connected to a main branch conductor

In the connectors of the pnor art, to ensure an adequate connection is made either the respective channels have to be of an appropπate particular size to receive to the cables desired to be joined, or such measures will need to be resorted to as bendmg the cable ends double or "packing out", whereby a void in the connector is filled with the same conductive mateπal

SUMMARY OF THE INVENTION

It is an object of the present mvention to provide a mechamcal connector of the type descnbed which is capable of handling cables which differ in size over a wider range than heretofore possible

According to the mvention there is provided a mechamcal connector compnsing a channel housmg for receiving electncal cables to be connected, a cable clampmg plate retamed in the housing, a support plate mounted to the housmg for carrymg clamping bolts or screws, the screws or bolts bemg of a predetermined length and having an allowable extent of travel relative to the support plate to engage the clampmg plate and clamp the cables a clampmg zone between the clampmg plate and the inner wall of the channel housmg characterised in that said support plate is mvertable m said channel housing by means of cooperating mounting elements therebetween, said support plate having means for varying the allowable extent of travel of the bolts or screws towards the clamping plate in dependence on the inverted position of the support plate m the channel housmg thereby to cater for an mcreased range of cable size which can be clamped in the clampmg zone

Preferably the inner walls of the channel housmg are provided with opposmg grooves m which the support plate may slide m any inverted position thereof

Advantageously, the support plate has mounting flanges for engagement in the grooves which are comphmentaπly shaped to the flanges, and a body portion extending from the flanges to form opposing support piate faces, one of which is further from the flanges than the other

With this aπangement, the oπfices for the bolts and screws extend through the support plate from one support plate face to the other such that the distance of travel of the bolts or screws towards the clampmg plate may be vaned in accordance with the particular inverted position of the support plate in the channel housmg.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will become apparent from the followmg descπption of a prefeπed embodiment of the invention made with reference to the accompanying drawings wherein,

Fig 1 is a cutaway perspective view of an electπcal connector according to the mvention; Fig 2 is an end elevation of the connector shown in Fig 1 with a bolt support bridge piece in a first position; and

Fig 3 is an end elevation of the connector shown in Fig 1 with a bolt support bridge piece in a second position.

PREFERRED EMBODIMENTS OF THE INVENTION

The electπcal connector shown m the drawings is compπsed of a U-shaped channel 1 for receivmg the ends of cables (not shown) to be connected abutting relationship.

The channel 1 contams a pair of bolt support bπdge pieces 2, each bπdgmg piece 2 being provided with two threaded oπfices 3 as to receive two shear head clampmg bolts 4 or screws mountable for screwable motion from either end of the threaded oπfices. The bolts or screws 4 have a shear throat which is designed so that the head of the bolt 4 will shear from the threaded stem portion when the bolt 4 has been tightened to a predetermined tension conesponding to a sufficient clampmg pressure.

It is, of course, possible to use bolts or screws without such a predetermined shearing capability, but this will render the conect clamping pressure more difficult to gauge.

The lower ends of the bolts 4 engage the top surface 5' of a pressure plate 5 loosely fitted widiin the channel 1, the underside surface 5" of which is convex. The bridge pieces are in die form of flat plates 2 of rectangular cross section.

The plates 2 have a body portion 2' in sliding relationship with the inner surfaces of me walls of tiie channel 1 and anomer body portion 2" in d e form of dove-tailed flanges slidable in conesponding dove-tailed grooves 6 formed in the walls of me channel 1.

The support plates 2 are dius invertable in the grooves 6 such mat that body portion 2' of the plate 2 is either in an upward position widi respect to the flange portion 2" as shown in Fig 2, or in a downward position as shown in Fig 3, so providing a variable upper surface level of ie plate 2 with respect to the base of uie channel 1.

With a given bolt length, uierefore, the maximum depύi of screwable movement through the support plate 2, and uierefore the depth within the channel 1 of the pressure plate 5 contacted by the bolt 4 may be made variable depending on me inverted position of tiie plate 2 in the grooves. In tiϋs way the dimension of ύie channel portion for die cable to be received may be altered to suit the cable in hand.

This permits, for example, cables having a wide range of differing dimensions to be anchored in die channel 1 as die pressure plate 5 holds d e cable against the channel base, by having d e bolt support plates 2 in d e position of Fig 2 to suit a larger range of cable size and in uie inverted position of Fig 3 to suit a smaller range of cable size. - o -

Furthermore uie structure permits two cables of diffenng cable core cross- section to be anchored reliably and consistendy in tiie connector by having one bolt support plate 2 in an inverted position witii respect to die odier.

In use d e insulating layer is removed from each respective core to a lengtii equal to that of d e pressure plate 5. The core having been straightened, the connector is d en assembled around ie conductor by inserting d e pressure plates 5 and bridge plates 2 as shown in die drawings whereby d e bolts 4 may be tightened until such time as d e shearing tension is reached whereupon the bolt head shears ensuring that a proper engagement has been made wit the conductor.

The respective portions of the connector may be manufactured from any material having d e requisite mechanical strength and providing the necessary electrical connection, for example typically aluminium.

Copper conductors may be wrapped in a brass gauze (not shown) pnor to insertion in die connector to ensure electrical stability between the copper and aluminium.

The base of the U-shaped channel 1 may be grooved as to increase the degree of engagement as the pressure plate 5 tightens uie cable occupying die channel 1 against its base.

Claims

1. A mechanical connector compnsmg a channel housing for receivmg electrical cables to be connected, a cable clamping plate retamed m d e housing, a support plate mounted to die housing for carrymg clamping bolts or screws, the screws or bolts being of a predetermined lengtii and havmg an allowable extent of travel relative to Uie support plate to engage die clampmg plate and clamp tiie cables m a clamping zone between the clamping plate and d e inner wall of tiie channel housing charactensed in tiiat said support plate is mvertable in said channel housing by means of cooperating mountmg elements d erebetween, said support plate having means for varying the allowable extent of travel of the bolts or screws towards d e clamping plate in dependence on die inverted position of d e support plate in the channel housmg thereby to cater for an increased range of cable size which can be clamped in die clamping zone

2. A mechamcal connector as claimed in claim 1 wherem the inner walls of die charmel housmg are provided witii opposing grooves m which the support plate may slide m any inverted position thereof

3. A mechamcal connector as claimed in claim 2 wherein die support plate has mounting flanges for engagement in uie grooves which are of complimentary shape to the flanges, and a body portion extending from the flanges to form opposing support plate faces, one of which is further from the flanges dian die other.

4. A mechamcal connector as claimed in claim 3 wherein said oπfices extend dirough die support plate between said opposing support plate faces such that die bolts or screws have a further distance to travel towards d e clampmg plate from said one support plate face than said odier support plate face in a respective required inverted position of die support plate m the channel housmg.

5. A mechanical connector as claimed in claim 4 wherem die channel grooves and the support plate flanges are provided in the form of dovetail jomts.

6. A mechamcal connector as claimed in any preceding claim wherein die clampmg plate and die support plate are provided in two halves such that each of d e respective halves may be independently adjusted securely to retain die cables to be electπcally connected.

7 A mechamcal connector as claimed in any preceding claim wherein die screws or bolts have tension dependent sheanng heads to ensure mat a correct tightening pressure is applied to uie clamping plate

8. A mechamcal connector as claimed in any preceding claim wherem die channel is U-shaped.

9. A mechanical connector compnsing a channel for receiving electπcal cables to be connected, a clampmg plate retamed in the channel, clampmg bolts or screws mounted in a support plate slidable between die walls of die channel to permit the bolts to be tightened on die clamping means to secure the cables m d e channel, charactensed in mat d e support plate and die channel have cooperating mountmg elements which permit d e plate to be slidably mounted in an up-side-down position in die channel, said support plate having a body portion or portions formed on one side d ereof which are at a closer spatial distance from die inner channel wall uian d e other side diereof in one slidable position in die channel such as to extend die range of cable sizes which can be retained in d e channel.