GB2093280A

GB2093280A - Insulation Piercing Contacts

Info

Publication number: GB2093280A
Application number: GB8104583A
Authority: GB
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 1981-02-13
Filing date: 1981-02-13
Publication date: 1982-08-25
Also published as: GB2093280B

Abstract

An insulation displacement electrical connector contact element has a conductive tubular body (20) with an opening (30) through its side wall and enclosed thereby which comprises a first region (31) for receiving an insulated electrical lead (40) and a second region (32) of reduced width into which the lead is arranged to be urged during insertion of the contact element into a housing (11), the sides of the body wall defining region (32) being adapted to penetrate through the lead insulation. The element may include a second opening of corresponding shape to, and diametrically opposite, the first- mentioned opening. A plurality of such pairs of openings may be provided along the length of the element for interconnecting a number of leads. <IMAGE>

Description

SPECIFICATION Electrical Connectors and Contact Elements for Use Therein This invention relates to electrical connectors and to contact elements for use therein.

The invention relates in particular to electrical connectors and contact elements for use with electrical leads, wires and the like which comprise a conductive core surrounded by an outer insulative covering, and is especially concerned with electrical connectors employing contact elements of the kind which are adapted to sever or penetrate the outer insulative covering of such electrical wires and engage electrically with the inner, conductive core. Such electrical connectors are commonly referred to as insulation displacement connectors.

Itis one object of the present invention to provide an improved form of contact element for use in electrical connectors of this type.

According to one aspect of the present invention, there is provided an electrical contact element for use with an electrical lead, for example wire, of the kind having an inner conductive core surrounded by an outer insuiative covering, comprising a tubular body of electrically conductive material having an opening through its side wall leading to the bore of the tubular body which comprises a first region adapted to receive an electrical lead therethrough and a second region of reduced width extending from and communicating with the first region into which the electrical lead is to be passed, the walls of the tubular body defining the second region being adapted to penetrate through the insulative covering of the lead and engage electrically with the conductive core.

The tubular body defining the opening is preferably continuously walled, and, in this respect, may be machined from a unitary piece of conductive material.

The second region of the opening may comprise an elongate slot communicating at its one end with the first region and closed at its other end by the tubular body wall. The opening may be generally 'key-hole' shaped with the elongate slot extending substantially parallel to the axis of tubular body.

The bore of the tubular body is preferably open at at least one end thereof. In the case where the bore of the tubular body is open at one end only, the body may include an inclined surface at the other end thereof for directing an end of an electrical lead through the bore and opening of the body.

The tubular body may include a second opening, of generally similar shape to the firstmentioned opening, in the wall of the tubular body diametrically opposite to the first-mentioned opening. In this case, the second and firstmentioned openings are arranged to receive a electrical lead passing transversely through the tubular body.

The contact element may include a pin or a socket preferably formed integrally with the tubular body, which is adapted to co-operate with an electrical socket or pin respectively.

Alternatively, the tubular body of the contact element may include a plurality of such pairs of openings at spaced intervals along the body for receiving and interconnecting respective plurality of electrical leads.

The contact element may also include means for mounting the element in, for example, a bore of an insulative housing.

According to another aspect of the present invention, there is provided an electrical connector including one or more contact elements in accordance with the above one aspect of the present invention, and a housing having one or more bores therein which are arranged to receive a respective one of the one or more contact elernents.

In such a case, the housing may include means thereon for urging an electrical lead into the second region of the opening in the tubular body of the contact element during insertion of the contact element in the bore of the housing.

Various other apects and features of the present invention will become apparent from the following description of several forms of electrical connectors and contact elements for use therein.

Various electrical connectors and contact elements for use therein, in accordance with the present invention, will now be described, by way of example,with reference to the accompanying drawings in which: Figure 1 is a plan view of part of one form of electrical connector shown during assembly; Figures 2 to 4 are side views, partly in crosssection, of the electrical connector of Figure 1 showing various stages of its assembly; Figure 5 is a plan view of part of a second form of electrical connector shown during assembly; Figures 6 to 8 are side views, partly in crosssection, of the electrical connector of Figure 5 showing various stages in its assembly; Figure 9 is a cross-sectional view from one side of a third form of electrical connector shown during assembly; and Figure 10 is a schematic plan view of the assembled electrical connector of Figure 9.

Referring to Figures 1 to 4 of the accompanying drawings, there is shown, at various stages of its assembly, a first form of electrical connector. This connector is of the kind having an insulative housing and an electrical contact element mounted in the housing which is to be coupled electrically to an electrical lead or wire and which provides a contact pin. Such a connector may comprise for example, one half of a two-part connector: the other half (not shown) having a socket mounted in a cooperating housing suitably arranged to mate with the contact pin of the contact element.

The connector, generally designated at 10, includes a housing 11 of insulative material such as polyester or glass-filled DAP plastics, which has a bore 12 extending completely therethrough that is adapted to receive, and retain, the contact element 14. The bore 12 is of circular crosssection and has a reduced width section 1 5 approximately mid-way therethrough which defines a pair of annular shoulders 16 and 17. The housing 11 also includes a U-shape recess 13 adjacent one end of the bore 1 2.

The contact element 12 is formed from a unitary piece of electrically conductive material, such as brass, berylluim-copper or phosphor bronze, by machining, and comprises a contact pin portion 18, a wire-receiving portion 20, and a cyiindrically-shaped intermediate portion 1 9. The portions 18 and 19 are solid. The contact pin 18 is flared outwardly at its one end towards the intermediate portion 1 9 and is separated therefrom by an annular bead 21.

The intermediate portion 1 9 is separated from the wire-receiving portion 20 by a further annular bead 22.

A retaining sleeve 23, comprising a strip of resilient material having outwardly projecting fingers 24, is wrapped around the intermediate portion 1 9 and restrained from axial displacement by the beads 21 and 22.

The wire-receiving portion 20 of the contact element is machined by drilling along approximately half its length to define a generally tubular body whose bore 25 extends axially of the contact element and which is open at its end 26 remote from the portion 19. In this way, the tubular body is formed as an integral and continuously-walled structure with the bore 25, and the entrance thereto at the end 26 of the portion 20, being surrounded by the continuous and substantially rigid wall of the tubular body.

An opening 30 is formed through the side wail of the wire-receiving portion 20 and communicates with the bore 25 of the tubular body of portion 20. As can be seen from figures 1 and 2 in particular, this opening 30 is generally of a 'key-hole' shape and comprises a first, substantially oval-shape, region 31, and a second region 32 in the form of an elongate slot of reduced width which communicates with the first region 30 and which extends axially of the tubular body away from the first region 30 towards the end 26 of the portion 20. The major axis of the oval-shaped region 31 extends substantially parallel to the longitudinal axis of the contact element. The axis of the elongate slot of the second region 32, which is of generally uniform width, lies on a continuation of this major axis.

The elongate slot of the opening 30 terminates away from the end 26 of the tubular body such that a section of the continuous wall of the tubular body separates the opening 30 from the open end 26.

An inclined surface 35 is provided at the innermost end of the bore 25 for the purpose of guiding an electrical wire through the bore 25 and the opening 30 as will be described more fully hereinafter. This surface 35 slopes downwardly from one edge of the opening 30 towards the open end 26 of the tubular body and extends approximately the length of the first region 31 of the opening 30.

Assembly of the electrical connector will now be described with reference to Figures 2 to 4 in particular. As shown in Figure 2, the contact element 14 is first partially inserted into the bore 12 of the housing 11 such that the wire-receiving portion 20 remains exposed. As electrical lead or wire, generally designated 40, to be coupled to the contact element and comprising an inner conductive core 41 and an outer insulative covering 42, is offered to the open end 26 of the tubular body of the portion 20 and inserted end first into the bore 25. The end of the lead 40 is passed through the bore 25 and directed by the inclined surface 35 upwardly through the region 31 of the opening 30 into the position shown in Figure 3.

A suitable tool (not shown) is then applied against the end 26 of the contact element 14 and moved towards the housing 11 so as to urge the contact element 14 further into the bore 1 2 of the housing 11 until the contact pin 1 8 projects from the other side of the bore 12, and, as shown in Figure 4, the bead 22 on the contact element abuts the annular shoulder 1 7 to prevent further axial displacement As this happens, the resilient fingers 24 of the retaining sleeve 23 pass through the restricted section 1 5 of the bore 12 and spring outwardly to engage behind the annular shoulder 1 6 so as to locate securely the contact element 14 within the bore 12.

During insertion of the contact element 14 in this manner, the upwardly extending end pf the electrical lead 40 is carried by the contact element into the recess 13 in the housing 11 and bent back upon itself by the inner wall of the recess 13. Thereafter, further displacement of the contact element 14 urges the end portion of the lead 40 rearwardly with respect to the contact element towards the end 26. In so doing, the lead 40 is forced into the elongated slot region 32 of the opening 30 whereupon the walls of the tubular body defining the elongate slot 32 penetrate through the outer insulative covering 42 of the lead 40 and, as shown in Figure 4, engage electrically with the inner conductive core 41.

A cover, not shown, may be secured to the housing 11 over the exposed end of the lead 40 by way of protection.

The generally U-shaped bend formed in the end portion of the lead 40 as a result of this operation assists in preventing the lead 40 from being withdrawn from the contact element in the event of tension being inadvertently applied to the lead. The end region of the tubular body of the contact element may be crimped around the lead 40 to provide additional securance should this be required.

In order to ensure satisfactory engagement between the lead 40 and the contact element, the respective widths of the regions 31 and 32 of the opening 30 are suitably chosen beforehand to accommodate the particular cross-sectional dimensions of the lead and its inner conductive core respectively which is to be used with the connector.

It is envisaged that the electrical lead may be inserted into the wire-receiving portion 20 of the contact element 14 in the opposite sense to that described above and such that the free end of the electrical lead is inserted firstly through the opening 30 from above the housing 11 and then through the bore 25.

This arrangement would be beneficial in applications where space available at the back of the connector is limited and entry of the lead from the side is desired.

Referring now to Figures 5 to 8 of the accompanying drawings, there is shown a second form of electrical connector which is a modification of the connector described hereinbefore. This connector is in many respects similar to the first form of connector, and, accordingly, corresponding components are designated with the same reference numerals.

This second form of connector differs from the connector of Figures 1 to 4 in that the recess 13 described previously is replaced by a U-shape channel 50 in the housing 11 which extends transversely of the bore 1 2 across the height of the housing 11.

The wire-receiving portion 20 of the contact element 14 is also modified and has a further opening 30' in its side wall diametrically opposite the opening-30. The opening 30' is identical in shape to the opening 30 and, like the opening 30, includes a first region 31' and second region 32' that communicate with the bore 25 of the tubular body. The inclined surface 35 of the previously described connector is replaced by a transverse wall 51 which is defined by the drilling of regions 31 and 31' during machining of the contact element.

Assembly of the second form of connector is generally similar to that of the first form of connector and will now be described with particular reference to Figures 6 to 8.

As before, the contact element 1 4 is initially inserted part way into the bore 12 of the housing 11. An electrical lead 40 to be coupled to the contact element is inserted transversely of the contact element through the regions 31 and 31' of the openings 30 and 30' respectively, as shown in Figure 7.

A cover plate 55, having a recess 56 for receiving the open end 20 of the contact element 14 and a generally U-shape channel 57 extending across its height, is aligned with the housing 11 and positioned against the end of the contact element. Pressure is then applied to the cover plate 55 to urge the contact element 14 into the bore 12 until it is located, by abutment of the head 22 with the shoulder 17 and engagement of the fingers 24 of the retaining sleeve 23 with the shoulder 16, in the position shown in Figure 8.

In displacing the contact element 14 with respect to the housing 11 in this manner, the electrical lead 40 is carried by the contact element into the U-shape channel 50 and is thereafter forced rearwardly of the contact element into the elongate slot regions 32 and 32' of the openings 30 and 30', whereupon the respective edges of tubular body of the portion 20 defining the regions 32 and 32' penetrate the outer insulative covering 42 of the lead 40 and electrically engage the inner conductive core 41, as is shown in Figure 8.

In this assembled condition, the end portion of the lead 40 is located in, and clamped firmly by the respective channels 50 and 57 in the housing 11 and cover plate 55.

The cover plate 55 may be secured to the housing by any suitable means such as, for example, screws.

With regard to both the first and second forms of connectors it is envisaged that, instead of being provided with an integral contact pin, 18, as described hereinbefore, the contact elements, 12, of the first and second forms of connectors may alternatively include a socket formed integrally with the wire-receiving portion. This socket may be adapted to mate with a contact pin which, in the case where the above described connectors comprise one half of a two-part connector, is carried in a suitably co-operating housing that constitutes the second half of the two-part connector.

Furthermore, it will be appreciated that although one contact element has been shown and described with reference to Figures 1 to 4 and Figures 5 to 8, in each case the housing 11 may include a plurality of bores 12, possibly in staggered relationship, and that a corresponding number of contact elements may be disposed in those bores so as to provide a multi-way connector of the pin or socket type. Such a connector could advantageously be used as a connector for a ribbon-cable form of electrical lead.

Referring now to Figures 9 and 10, there is shown a third form of electrical connector which is intended to be used for electrically interconnecting two or more electrical leads.

The connector comprises a housing 60, a contact element 61 and an end cap 62.

The housing 60, which is of insulative material and generally rectangular, has a bore 63 therein of circular cross-section which is closed at one end and which opens at its other end through an externally screw-threaded projection 64 of the housing. The housing 60 also includes, in this particular case, three bores, 65, 66 and 67 which extend through the housing 60 transversly of the bore 63 at regularly spaced intervals and which open through one side of the housing 60.

The contact element 61 comprises a continuous walled tubular body, open at both ends, which is of circular cross-section and adapted to fit slidingly within the bore 63 of the housing. The contact element 61 is machined from a unitary piece of may suitable electricallyconductive material.

Formed in the side wall of the tubular body of the contact element 61, are three pairs of diametrically opposed openings 68 and 68' which are spaced from one another by an amount corresponding to the separation between adjacent ones of bores 65, 66 and 67. Each pair of openings 68 and 68' is generally similar to the pair of openings 30 and 30' in the tubular body of the contact element 1 4 described with reference to Figures 5 to 8. More particularly, and as can be seen clearly in the plan view of Figure 10, each of the openings 68 and 68' consists of a generally 'key-hole' shape having a first, substantially oval, region, 69 and 69', and a second region, 70 and 70' respectively, in the form of a reduced-width elongate slot that communicates with the first region 69 and 69' and extends axially of the tubular body.

The end cap 62 is prismatic to facilitate gripping and has a cylindrical recess 72 which is screw-threaded and adapted to co-operate with the screw-threaded projection 64 of the housing 60.

The connector is assembled by firstly sliding the contact element 61 within the bore 63 such that the first region 69 and 69', of each pair of openings 68 and 68' is aligned with a respective one of the transverse bores 65,66 and 67, as shown in Figure 9. In this position, one end of contact element 61 projects a predetermined distance out of the bore 63.

An electrical lead 40 is then inserted into each of the transverse bores 65, 66 and 67 and through the aligned respective pair of openings 68 and 68' in the tubular body of the contact element until it abuts the closed end of its respective bore.

Following this, the end cap 62 is screwed onto the projection 64 of the housing 60 to urge the contact element 61 further into the bore 63. In so doing, the leads 40, being constrained against movement axially of the bore 63 by the walls of the transverse bores 65, 66 and 67, are forced by this relative displacement between the contact element 61 and the housing 60 to enter the elongate slot regions 70 and 70' of their respective associated pair of openings 68 and 68' in the contact element 61 whereupon the edges of the tubular body defining the elongate slot regions 70 and 70' penetrate through the outer insulative covering 42 of the leads 40 and electrically engage the inner conductive core 41 thereof so as to interconnect electrically the leads 40.

The final position of the contact element 61 with respect to the housing 60 is shown in Figure 1 0. The leads 40 have been omitted from this figure for clarity. It can be seen that, once assembled, the connector is fully insulated as the contact element 61 and the ends of the leads 40 are completely encased by the insulative housing 60 and end cap 62.

Observation ports, not shown in Figures 9 and 10, may be provided in the housing 60 leading to the transverse bores 65, 66 and 67 through which the ends of the leads 40 may be viewed during their insertion into the bores. These ports preferably open into the bores 65, 66 and 67 at a position along the section of the bores between their closed ends and the contact element 61 so that a person assembling the connector can observe that the leads 40 are inserted completely through the openings in the contact element 61.

Although a connector capable of interconnecting three electrical leads has been described and shown with reference to Figures 9 and 10, it will be appreciated that by appropriately varying the number of transverse bores in the housing, and the number of the associated openings 68 and 68' in the contact element, the connector can be adapted to interconnect two or more than three electrical leads.

Furthermore, it is envisaged that the bore 63 of the housing 60 and the outer surface of the contact element 61 may have respective flat surfaces or other means that co-operate with one another during insertion of the contact element 61 into the bore 63 to prevent rotation of the contact element 61 within the bore 63 and ensure that the openings 68 and 68' through the contact element are correctly aligned with the transverse bores. In this respect, the outer surface of the contact element 61 and the bore 63 may be prismatic.

With regard to the three forms of connectors as heretofore described, it is envisaged that the precise shapes of the regions 31 and 32, 31' and 32', 69 and 70,69' and 70' of the openings 30, 30' 68 and 68' respectively may be modified slightly to accommodate electrical leads of different cross-sectional configuration. In this respect, the first region of each of the openings may for example be generally circular rather than oval in shape. Furthermore, the first regions may include a flared lead-in portion to the second regions to assist in guiding the electrical lead into that region.

Claims

1. An electrical contact element for use with the electrical lead of the kind having an inner conductive core surrounded by an outer insulative covering, comprising a tubular body of electrically conductive material having an opening through its side wall leading to the bore of the tubular body which comprises a first region adapted to receive a said electrical lead therethrough and a second region of reduced width extending from and communicating with the first region into which the electrical lead is to be passed, the walls of the tubular body defining the second region being adapted to penetrate through the insulative covering of the lead and egage electrically with the conductive core thereof.

2. An electrical contact element according to Claim 1, wherein said tubular body is continuously walled.

3. An electrical contact element according to Claim 2, wherein said tubular body is machined from a unitary piece of conductive material.

4. An electrical contact element according to any one of the preceding claims, wherein the second region of said opening comprises an elongate slot communicating at its one end with the first region of said opening and closed at its other end by the tubular body wall.

5. An electrical contact element according to Claim 4, wherein said opening is generally 'keyhole' shaped with the elongate slot comprising said second region extending substantially parallel to the axis of the tubular body.

6. An electrical contact element according to any one of the preceding claims, wherein the bore of the tubular body is open at one end thereof.

7. An electrical contact element according to Claim 6, wherein the contact element includes a surface underlying the first region of said opening which is inclined with respect to the axis of the tubular body and which defines the other end of the bore thereof.

8. An electrical contact element according to any one of Claim 1 to 6, wherein the tubular body includes a second opening through its side wall which is diametrically opposite to, and corresponds substantially in shape with, said firstmentioned opening and wherein said second and first-mentioned openings are arranged to receive a said electrical lead passing transversely through the tubular body.

9. An electrical contact element according to Claim 8, wherein the second region of said second opening is adapted to penetrate through the insulative covering of said electrical lead and engage electrically with the conductive core thereof.

1 0. An electrical contact element according to any one of the preceding claims, wherein the contact element includes electrically-conductive pin adapted to co-operate with an electrical socket.

11. An electrical contact element according to Claim 10, wherein said pin is formed integrally with said tubular body.

12. An electrical contact element according to any one of Claims 1 to 9, wherein the contact element includes an electrically conductive socket adapted to co-operate with an electrical pin.

13. An electrical contact element according to Claim 12, wherein said socket is formed integrally with said tubular body.

14. An electrical contact element according to Claim 8 or Claim 9, wherein the tubular body includes a plurality of said second and firstmentioned openings at spaced intervals along its length for receiving and interconnecting a respective plurality of said electrical leads.

1 5. An electrical contact element according to any one of Claims 1 to 13, wherein the contact element includes means for facilitating mounting thereof in a bore of a housing.

1 6. An electrical contact element substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

1 7 An electrical contact element substantially as hereinbefore described with reference to Figures 5 to 8 of the accompanying drawings.

1 8. An electrical contact element substantially as hereinbefore described with reference to Figures 9 and 10 of the accompanying drawings.

19. An electrical connector including one or more contact elements in accordance with any one of the preceding claims, and a housing having a corresponding numbers of bores therein and adapted to receive a respective one of the one or more contact elements.

20. An electrical connector according to Claim 19, wherein the housing includes means thereon for urging a said electrical lead into the second region of the opening in the tubular body of the contact element during insertion of the contact element into the bore of the housing whereby the insulative covering of said electrical lead is penetrated by the walls of the tubular body defining said second region.

21. An electrical connector according to Claim 20 and Claim 9 wherein the housing includes means thereon for urging a said electrical lead into the second region of the second opening in the tubular body of the contact element during insertion of the contact element into the bore of the housing whereby the insulative covering of said electrical lead is penetrated by the walls of the tubular body defining said second region of the second opening.

22. An electrical connector according to Claim 21, wherein the connector includes a member adapted to be mounted on and displacable relative to said housing which is arranged to move said contact element axially within its bore when displaced relative to said housing.

23. An electrical connector substantially as hereinbefore described with reference to Figurest 1 to 4 of the accompanying drawings.

24. An electrical connector substantially as herein before described with reference to Figures 5 to 8 of the accompanying drawings.

25. An electrical connector substantially as hereinbefore described with reference to Figures 9 and 10 of the accompanying drawings.