Connector and Connection Method

The present invention relates to a method for making an electrical connection between two electrical conductors and to connectors suitable for use in such a connection.

Heat-recoverable sleeves have been widely used in the making of electrical connections, the change in dimensions of such a sleeve on heating being in some cases used only to ensure, for example, that a sleeve which is large enough to be slipped easily over a joint to be insulated is, after heating, a tight fit about the joint, and in other cases used also, or alternatively, to, for example, move or exert pressure on another substance or object. Thus, for example, if a heat-shrinkable sleeve contains a fusible material (for example solder) as disclosed in U.S. Pat. No. 3,243,211, the fusible material may be forced, on shrinking of the heat-shrinkable sleeve, into close contact with a substrate within the sleeve. Whether or not a substance such as a fusible material is present, the shrinking of a heat-shrinkable sleeve may also act to move together, or to maintain together, two electrical conductors inserted in the sleeve so that a reliable electrical connection can be made between them.

Although heat-recoverable sleeves such as those described in U.S. Pat. No. 3,243,211 have proved very satisfactory for a wide number of applications in the making of electrical connections, problems may be encountered where a connection is to be made between relatively thick single conductors. Thus, for example, the force exerted by a heat-shrinkable sleeve of an appropriate size during shrinking may not always be sufficiently great to bring thick conductors close enough together for a reliable electrical connection to be made; when thick conductors are inserted side-by-side through the same end of a sleeve they may have a tendency to spring apart, a tendency which will not necessarily be overcome by twisting the conductors together before inserting them into the sleeve.

The present invention provides a method of making an electrical connection between two electrical conductors which, in addition to making the electrical connection, includes the steps of positioning the conductors within a heat-shrinkable sleeve such that each conductor extends out of a first end of the sleeve, the conductors being held, by an insert positioned within the sleeve, in a substantially fixed transverse relationship to each other in the sleeve whereby an electrical connection can be made between the conductors, the insert being infusible at the temperature to which the components are heated to cause shrinkage of the sleeve, and applying heat to shrink the sleeve. The insert is advantageously positioned in the sleeve before the conductors are positioned in the sleeve.

The invention also provides a method of making an electrical connection between two electrical conductors which, in addition to making the electrical connection, includes the steps of inserting each conductor into a first end of a heat-shrinkable sleeve at least the first end of which is open, the sleeve having an insert therein, which insert is infusible at the temperature to which the components are heated to cause shrinkage of the sleeve and is such that it holds the conductors in a substantially fixed transverse relationship to each other whereby an electrical connection can be made within the sleeve between the electrical conductors, and applying heat to shrink the sleeve.

The present invention further provides a method of making an electrical connection between two electrical conductors which, in addition to making the electrical connection, includes the steps of inserting each conductor into a first end of a heat-shrinkable sleeve open at at least the first end, the sleeve having an insert therein, which insert is infusible at the temperature to which the components are heated to cause shrinkage of the sleeve and provides at least two compartments side-by-side to each other in the sleeve, each conductor being received in a different compartment whereby an electrical connection can be made within the sleeve between the electrical conductors, and applying heat to shrink the sleeve.

In accordance with the invention, the electrical connection between the conductors may be made by any desired method. Thus, for example, the connection may be made by one of the steps recited above, for example merely by positioning the conductors in the insert, or by some other step which may or may not be carried out substantially simultaneously with one or more of the steps recited above.

The electrical connection may, for example, be made or enhanced by solder and/or made or enhanced by direct contact of the conductors. If the insert is electrically conductive, the electrical connection may be made through the insert although unless the conductors are pretinned and are relatively closely received in the insert, it will normally be necessary, if the connection is to be made through the insert, for the connector to contain a quantity of solder, for example as a layer on the interior of the insert or in such a position that on fusing it can flow or be forced into the interior of the insert, to ensure that a reliable connection is made between each conductor and the insert. Preferably, however, an electrical connection is made between the conductors which is independent of any electrical connection of the conductors through the insert, the independent connection advantageously being made or enhanced by solder and/or made or enhanced by direct contact of the conductors.

An advantageous method of making or enhancing an electrical connection between the conductors by direct contact of the conductors comprises twisting together portions of the conductors which are within the sleeve but which are not held by the insert. The said portions are advantageously twisted together by rotating the connector about its longitudinal axis while rotational movement of the portions of the conductors extending out of the connector is substantially prevented. Where an electrical connection between the conductors is made or enhanced by solder, the heat-shrinkable sleeve may, for example, contain a quantity of solder, heat being applied to cause the heat-shrinkable sleeve to shrink and to cause the solder to fuse and to make or enhance an electrical connection between the conductors. Where the sleeve contains a quantity of solder the insert must of course be infusible at the temperature to which the connector is heated to cause the sleeve to shrink and the solder to fuse.

The invention also provides a method of making an electrical connection between two electrical conductors which method includes the steps of inserting the conductors into the first end of an electrically conductive insert comprising at least two compartments side-by-side to each other whereby an electrical connection is made between the conductors, each conductor being received in a separate compartment, inserting the assembly into a heat-shrinkable sleeve having at least one open end, and applying heat to shrink the sleeve, the insert being infusible at the temperature to which the components are heated to shrink the sleeve.

The invention also provides a heat-recoverable connector suitable for making an electrical connection between two electrical conductors, which comprises a heat-shrinkable sleeve at least a first end of which is open, an insert positioned within the sleeve, the insert being such that it can hold the conductors in a substantially fixed transverse relationship to each other whereby an electrical connection can be made, within the sleeve, between the conductors, and a quantity of solder positioned within the sleeve between the insert and an end of the sleeve, the insert being infusable at the temperature to which in use the connector is heated to cause the sleeve to shrink and the solder to fuse.

The insert used in the method and article of the invention preferably provides at least two compartments in the sleeve, the compartments being side-by-side to one another; the walls of the compartments may, if desired, be laterally (transversely) spaced from one another, and the ends of the compartments need not necessarily be conterminous; all that is required is that at least one cross-section through the insert intersects both compartments. In use, each of at least two of the compartments receives a respective electrical conductor. The insert may, advantageously over part only of the length of the sleeve, merely divide the space within the sleeve into two or more compartments. Preferably, however, the insert itself comprises at least two compartments, that is, none of the compartments has a wall provided by a portion of the sleeve.

Where the insert provides a plurality of compartments, at least one of the conductors may, in the method of the invention, be engaged by the interior wall(s) of the compartment in which it is received. This, however, is not essential and some movement of the conductors relative to the insert (for example lateral movement in the compartments) may occur provided that the conductors are maintained in a substantially fixed transverse spatial relationship to each other so that an electrical connection can be made between them. Preferably, however, little or substantially no transverse movement of the conductors relative to the insert takes place. Advantageously, the insert also maintains the conductors in a substantially fixed longitudinal relationship to each other.

The invention further provides a heat-recoverable connector suitable for making an electrical connection between two electrical conductors, which connector comprises a heat-shrinkable sleeve at least a first end of which is open, and an insert positioned within the sleeve, the insert being infusible at the temperature to which in use the connector is heated to shrink the sleeve and comprising at least two compartments side-by-side to each other.

When the insert used in accordance with the invention comprises a plurality of compartments each compartment is preferably defined by a substantially tubular wall which is preferably joined to the other or another substantially tubular wall by a bridging member. The insert may, for example, be formed from a sheet of material opposite edges of which have been rolled towards each other to form the walls of the compartments, or may, for example, be formed from a generally cylindrical member, substantially diametrically opposed portions of which member have been deformed radially inwardly whereby the compartments are formed, the inwardly deformed portions forming a pair of bridging members between the substantially tubular walls of the compartments; the bridging members may be spaced apart from each other so that the compartments are in communication with each other. The connector preferably also comprises a quantity of solder positioned within the sleeve between the insert and an end of the sleeve.

When the heat-shrinkable sleeve used in accordance with the invention has a quantity of solder therein this may, if desired or required, be associated with a quantity of flux. The solder may be in any desired form, but is advantageously in the form of a ring. The solder is preferably positioned between the insert and the first end of the sleeve.

The heat-shrinkable sleeve used in accordance with the invention is a sleeve at least part of which will shrink on the application of heat and may comprise any material, advantageously an electrically insulating material, which may be converted to or maintained in a heat-shrinkable form. Examples of suitable materials are given, for example, in U.S. Pat. Nos. 3,086,242, 3,243,211 and 3,297,819, the disclosures of which are incorporated herein by reference. Crosslinked polymeric materials are particularly suitable. The sleeve may be open at one or both ends and may be provided at or in the vicinity of the or each open end with a quantity of fusible material or other sealing material to enhance the environmental seal at the end(s) of the heat-shrinkable sleeve. Thus, the sleeve can force fused fusible material into close contact with a conductor received in the open end of the sleeve to provide a reliable seal. Alternatively, the sleeve and fused fusible material could cooperate to produce a seal even at an open end that does not receive a conductor.

This insert may comprise any suitable material, but is advantageously electrically conductive, and preferably comprises a metal. The insert is advantageously substantially dimensionally stable (apart from normal thermal expansion) at the temperature to which the components are heated to cause the sleeve to shrink and the solder, if present, to fuse. The insert is preferably spaced from at least one end of the sleeve.

In accordance with the invention, a reliable electrical connection may be made between two conductors, for example conductors in telecommunication cables, even when these are relatively thick. Thus, the insert can maintain the conductors in position relative to each other so that an electrical connection can be made between them, for example by twisting and/or soldering, without the need to rely on the recovery forces of the sleeve to bring or maintain the conductors in the desired positions. Furthermore, when the insert is appropriately constructed, an electrical connection may be made between conductors inserted into the connector merely by twisting the connector about its longitudinal axis while movement of the portions of conductors extending out of the connector is substantially prevented.

Two embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-section through a connector according to the invention having two conductors inserted therein;

FIG. 2 shows the connector of FIG. 1 after twisting of the conductors;

FIG. 3 is an end view of the insert of the connector of FIG. 1;

FIG. 4 is a side view of the insert of the connector of FIG. 1;

FIG. 5 is a perspective view of a member which may be used for making a second insert according to the invention;

FIG. 6 is a perspective view of a insert made from the member shown in FIG. 5; and

FIG. 7 is a cross-section through the insert of FIG. 6.

Referring now to the drawings, FIG. 1 shows a connector indicated generally by the reference numeral 1 comprising a heat-shrinkable sleeve 2 of electrically insulating material, the sleeve having two open ends, 3 and 4 respectively. A ring 5 of solder is positioned within the sleeve 2 and rings, 6 and 7 respectively, of fusible polymeric material are positioned between the solder ring 5 and each of the open ends 3 and 4. The sleeve 2 also has positioned within it an insert indicated generally by the reference numeral 8, the insert being positioned between the solder ring 5 and the fusible insert 7.

As can be most clearly seen from FIGS. 3 and 4, the insert comprises a pair of compartments 9 defined by generally tubular walls joined by a bridging member 10. The insert may be formed from a single sheet of metal, opposite edges 11 and 12 of the sheet being rolled inwardly to provide the tubular walls.

The connector of FIGS. 1 to 4 may be used to make an electrical connection between two wires indicated generally by the reference numerals 13 and 14. A portion of the insulation 15, 16 is stripped from each of the wires 13 and 14 to give stripped end portions 17 and 18, and the stripped end portions 17 and 18 are introduced into the connector through the open end 3 of the heat-shrinkable sleeve 2. Each end portion is inserted in a compartment 9 of the insert 8, the insert thereby maintaining the end portions in substantially fixed spatial relationship to each other. Some movement of the end portions 17 and 18 in the compartments may be possible, but each end portion is maintained within the confines of the respective compartment. It will be noted that a part of each stripped end portion 17, 18 is positioned within solder rings.

The insert 8 makes it possible to make a reliable electrical connection between the stripped conductors. Thus, after insertion of the end portions 17 and 18 into the insert 9 to give the arrangement shown in FIG. 1, the connector may be rotated about its longitudinal axis while movement of the insulated portions of wires 13 and 14 is substantially prevented. The stripped portions of conductors adjacent to the insert 8 are thereby twisted into contact with each other at 19 (see FIG. 2). Although for simplicity only one twist is shown in FIG. 2, more than one twist may of course be made. The connector may then be heated to cause the heat-shrinkable sleeve 2 to shrink and the solder ring 5 and fusible rings 6 and 7 to fuse. The fused solder enhances the electrical connection made by twisting of the conductors, while the sleeve 2 and fusible insert 6 are forced into close contact with the wire insulation to form an environmental seal. The end 4 of the sleeve 2 is completely closed by the shrinking of the sleeve and the fusing of the fusible ring 7, so that the connection between the conductors is completely sealed from the environment.

Although the sleeve 2 in FIGS. 1 and 2 is shown as having two open ends, the end 4 could if desired be closed. Moreover, where a satisfactory electrical connection between the bared portions of the conductors can be made merely by twisting, the solder may be omitted. Alternatively, if solder is present, the twisting step may in some cases be omitted. The fusible rings 6 and 7 may also be omitted if circumstances are such that a satisfactory environmental seal may be made without them.

FIG. 5 shows a cylindrical member indicated generally by the reference numeral 20 which may be used for forming a second insert, indicated generally in FIG. 6 and 7 by the reference numeral 21, which may be used in accordance with the invention. The insert 21 is formed by deforming substantially diametrically opposite portions 22, 23 of the cylindrical member 20 radially inwardly thereby forming two compartments 24 each of which is defined by a substantially tubular wall and is joined by a pair of bridging members 25 to the other compartments, the inwardly deformed portions 22 and 23 providing the bridging members. The insert 21 could, for example, be used in place of the insert 8 of FIGS. 1 to 4.

It is to be understood that, in the method of the present invention, the resulting electrical connection between the conductors is effected without the necessity for dimensional change of the insert on shrinkage of the sleeve, although the possibility that incidental dimensional change takes place is not excluded. The article of the invention is accordingly so constructed as to enable this to be achieved.

References to the insert being substantially dimensionally stable are to the fact that the insert is not itself made of a material that is heat-recoverable at the shrinkage temperature or the fusing temperature of the solder, if present.