CA1123489A

CA1123489A - Electrical conductor having integral electrical contact and method of making

Info

Publication number: CA1123489A
Application number: CA319,943A
Authority: CA
Inventors: James R. Hall; William P. Whallon, Jr.
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1978-03-27
Filing date: 1979-01-19
Publication date: 1982-05-11
Also published as: GB2017424B; IT7921227A0; IT1112350B; DE2908692A1; GB2017424A; JPS54132789A; US4206958A; FR2421482A1; BR7901886A; FR2421482B1

Abstract

ABSTRACT

An electrical conductor (10) having at forward end portion (F) of the conductor an integral electrical contact portion consisting of a plurality of fine, axially aligned wire strands (21), each wire having an acutely angled end surface (22) for mating with another electrical contact, said contact wires being an integral part of and continuous with the wires of said conductor in a rear portion (R). Preferably, the wires in the forward portion of the conductor are held radially together by a sleeve or holder which is inserted over the forward end, around the wires and crimped in place, separating the rear portion (R) of the conductor, which generally has insulation (30) around the conductor for a portion of its length from the forward contact portion.

Description

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~ 23~8~ 370-77-0200 ELECTRICAL CONDUCTOR HAVING AN INTEGRAL
ELECTRICAL CONTACT AND METHOD OF MAKING

TECHNICAL FIELD

The present invention relates to electrical conductors. More particularly, the present invention relates to an electrical conduc-tor having an integral electrical contact as a termination on at -~ least one end thereof, said contact being suitable for mating with another contact. The present invention is also a novel method of making such a conductor.
BACKGROUND ART
Electrical conductors are well known in the prior art and have been in use for many years. Such prior art electrical conductors typically have a terminat;on on at least one end thereof to connect the conductor with another electrical element. Such a termination -typically has been obtained by coupling a separate piece (a contact) to the conductor. This disadvantageously necessitated the separate manufacture and inventory of separate contacts and the installation of such a separate contact to the conductor in order to couple the -~
contact with the conductor. Installation of the contact addition-ally required the preparation of the conductor to couple it with the contact. The separate manufacturing and storing in inventory ;~
steps and the preparation of the conductor adds undesirable ex-pense to the process of manufacturing a conductor. The preparation and assembly requires either the time of the workman or of the ~ -machine, both of which add expense to the manufacturing process.
Furthermore, the connection between a conductor and a contact is itself undesirable in that it adds electrical resistance to the circuit, where a lower resistance is usually desirable.
Furthermore, the making and assembling of separate pieces entails a multiple inspection of the individual pieces separately and then assembled. The additional pieces provide additional sources of potential failures and unacceptable products.
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'~ , ~3~3~ 370-77-0200 Prior art electrical conductor terminations "contacts" are sleeve like members having a forwarcl mating portion and a rear wire receiving portion. An electrical conductor having a plurality of wires is connected to the respective wires in another conductor by inserting each wire into the wire receiving portion of a contact and then connecting the mating end of each contact on one conductor to respective contacts on another conductor. One such electrical contact is described in U. S. Patent 3,725,844 to Mc~eown et al for "Hermaphroditic Electrical Contact"~ a patent which is assigned to the assignee of the present invention. The contact described in that patent has acutely angled end surfaces for mating with a similar contact in electrical circuit relationship. Such a contact has limitations similar to the other contacts discussed above, in that the contact consists of several piec.es, each separate from the conductor and assembly of the contact as well as the contact with the conductor is required. Further, the forward portion of the electrical conductor must be prepared for insertion within the sleeve.

1~l2348~
The present invention is a novel electrical conductor having an integral electrical contact and a method of making the conductor. The noveL conductor overcomes the undesirable features and limitations of the prior art conductors.
The apparatus of the present invention is especially suited for an electrical conductor in which a low manufacturing cost and a low electrical resistance is desired.
According to one aspect of the present invention there is provided an electrical conductor assembly which includes- a conductor comprised of a plurality of wire strands with a terminal at one end and a sleeve mounted around the wire strands at the other end. The sleeve is spaced from the other end to expose a predetermined length of the wire strands, the length of exposed wire strands at the other end being axially aligned with each other and the end of each strand being angled.
In a specific embodiment of the invention there `-is provided an electrical cable assembly including a cable having a plurality of electrical conductors, electrically insulatèd from each other and each conductor comprised of a plurality of wire strands. A sleeve is mounted on each `
conductor, the sleeve being spaced from one end of the conductor, the wire strands extending from the one end of the sleeve, being axially aligned with each other and the .. . .
end of each such strand having an acutely angled end surface.

~' mb/~ _ 3 _ ~2~89 In another ~orm of the present invention there is provided a method oE forming an integral electrical contact at a forward end of an electrical conductor, the method including the steps of removing the insulation from the forward portion of the electrical conductor to expose a plurality of strands at the forward end thereof, straightening and axially aligning the strands, forming an acutely angled surface at the forward end of each strand, and applying a sleeve around the aligned strands at a location spaced rearwardly from the forward end to maintain the strands in close proximity.
In one specific embodiment of the present invention, a plurality of strands without insulation are individually insulated, except in the forward contact portion, with a suitable insulating finish such as magnet wire varnish or !;
Kapton brand insulation. This electrically insulates the strands rearwardly of the forward contact portion while allowing the forward contact portion to remain exposed to connect the strands with another conductor in electrical ;
circuit relationship.
Other objects and advantages of the present invention will be apparent to one skilled in the art in view of the followlng description and claims and the accompanying drawings.

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/it~ - 4 -~ l23489 370-77-0200 BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a perspective view of an insulated multi-stranded conductor with the forward portion of the insulation removed to expose the conductor strands.
FIGURE 2 is a perspective view of the conductor of FIGURE 1 with a sleeve installed around the conductor ;n the forward portion.
FIGURE 3 is a view of the conductor of FIGURE 2 with the for-ward end portion of the stranded conductor cut at an acute angle.
FIGURE 4 is a view of the conductor of FIGURE 3 with the for-ward portion of the strands of the conductor straightened generally into axial alignment.
FIGURE 5 is a partial cross-sectional view of an electrical connector assembly having two electrical connector halves which are mateable together, each half employing a plurality of conduc-tors of the type described in FIGURES 1-4 shown prior to the -15 assembly of the connector halves. `
FIGURE 6 is a partial cross-sectional view of several electri-cal connector assemblies (of the type shown in FIGURE 5) mounted in connector housings or bodies.
FIGURE 7 is a cross-sectional view of a portion of FIGURE 6, looking in the direction of line 7-7, showing after the mating of the connector bodies and assemblies of FIGURE 6.
FIGURE 8 is a partial cross-sectional view of an insulated wire or conductor having a single conductive strand.
FIGURE 9 is a perspective view of the wire of FIGURE 8 after being cut and the forward insulation is removed.
FIGURE 10 is a cross-sectional view of a plurality of wires of the type shown in FIGURE 9 and assembled into a conductor and secured together at each end with a sleeve.
FIGURE 11 is a partial cross-sectional view of a cable assembly including a plurality of conductors of the type described in FIGURE 10.

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1234~39 FIGURE 12 is a perspective v~ew of three uninsulated wires or conductors.
FIGURE 13 is a perspective view of one of the conductors of FIGURE 12 after coating with an insulating material.
FIGURE 14 is a cross-sectional view of the conductor of FIGURE 13, looking along the line 14-14 in direction of the arrows.
FIGURE 15 is a fragmented view of a conductor made from a plurality of wires of the type shown in FIGURE 13.
FIGURE 16 is a fragmented view of a conductor made from a plurality of wires of the type shown in FIGURE 13, similar to that of FIGURE 15 with a different type of termination at one end thereof.
FIGURE 17 is a cross-sectional view of an electrical connection between two conductors similar to the conductor ~-shown in FIGURE 16.
DETAILED DESCRIPTION OF THE DRAWINGS ;`' FIGURE 1 shows an insulated conductor or wire 10 ,.
~ 20 which has a central stranded conductor 20 with electrical ;~"
, insulation 30 surrounding the conductor in a rear portion R.
The insulation in a forward portion F of the wire 10 has ~ -been removed to expose the stranded conductor 20, which ;;~
typically has several spirally-wound strands of copper or copper-weld (carbon steel core with copper plating) or copper alloy or stainless steel. The best material is believed to be copper-weld for rigidity and conductivity and relatively low expense. Another material for the . .
conducting wire 10 would be a stainless steel alloy core ' : ~, ~b//(~ - 6 -with an external coating of a material chosen from the group including gold, silver, rubidium, platinum, copper and copper-weld..
FIGURE 2 shows the insulated wire 10 of FIGURR 1 with a sleeve or holder 40 inserted over the forward portion F of the central stranded conductor 20. The holder 40 is held in place by an inward crimp 42 where the sleeve 40 has been crimped into the conductor 20.
FIGURE 3 shows the insulated wire 10 and the sleeve 40 of FIGURE 2 with the forward end of the wire cut to an acute angle ~. The cutting of the spirally wound conductor 20, because of the spiral winding, results in individual -strands 21 being of different lengths and each strand may have an end surface 22 with an angle which differs from the angle on the end surface on other strands.
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.' . . . `, , ~ ' ~ 3~9 370-77-0200 Preferably, all of the individual strands have an acutely angled, or tapering, end surface which assists in mating and in electrical characteristics. The acutely angled end surfaces are more fully described in U. S. Patent 3,725,844.

FIGURE 4 shows the insulated wire 10 of FIGURE 3 with the individual wire strands 21 straightened into axial alignment in the portion ot the strands forwarcl of the sleeve 40. The wire strands 21 in a prototype or small scale production might be straightened manually with hand tools such as pliers, however, in high scale production the wire strands 21 would preferably be straightened using automated equipment to comb the wire strands into a straight, axial aligned configuration, then urged together radi-ally to form a close bundle. The end surfaces 22 of the individual strands extend slightly differing lengths and have somewhat diverse angled end surfaces. The aligned strands are resiliently deflect-able in the radial direction as they are adapted to be mated and unmated with a similar or identical type contact.

FIGURE 5 shows portions of two wires or conductors 100, 200 prepared in the manner shown in FIGURES 1-4 and the accompanying description. The conductor 100 has a sleeve 110, which is mounted in a housing 120 and wire strands 130. The housing 120, which is made of a thermoplastic material or other suitable insulator, serves as protection for the wires before assembly and, after assembly into an electrical connection, serves to insulate the electrical connec-tion from the environment. The slèeve 110 which is preferably metallic, also is insulated by the housing 120 from the environment.
The housing 120 is provided with a forward bore 122, a rear bore 124 and a passage 126 connecting the bores 122, 124. The rear bore 124 is large enough to receive the holder 110 and the wire 100 even in the insulated region; the passage 126 is of a size small enough to prevent the holder 110 from passing through, but large enough to allow the wire strands 130 to pass therethrough.
The conductor 200 has a sleeve 210, which is mounted in a housing 220, and wire strands 230. The housing 220 is similar to the housing 120, having a forward bore 222, a re~r bore 224 and a .~

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~ 370-77-0200 l23~

passage 226, except that the forward end of the housing 200 is of a smaller size than the bore 122 of the housing 100 to allow the ex-ternal portion 228 to fit within the bore 122, allowing the mating of the strands 130 with the strands 230 to connect the conductors 100, 200 in electrical circuit relationship. When connected, the conductors 100, 200 form a single mated line or electrical connec-tion.
The housing 120 thus has a larger sleeve portion at its forward or mating region and the housing 220 has a smaller sleeve portion at its mating region. The smaller sleeve portion is adapted to inter-fit within the larger sleeve portion upon mating.
FIGURE 6 illustrates the use of a plurality of conductor assemblies 301-304 and 401-404 of the present invention. The con-ductor assemblies 301-304 are mounted to a body 300 and each include a conductor adapted to be mated with a conductor in respective con-ductor assemblies 401-404, which are mounted to a second body 400.
The bodies 300, 400 have a plurality of generally parallel passages for receiving the conductor assemblies. For ease in manufacturing and lower expense, the bodies 300, 400 are preferably made of plastic, although metal or other materials might be used, as the conducting wires are insulated from the bodies by the sleeves which are nonconducting. As shown in FIGURE 6, the conductor assemblies are arranged with alternating larger and smaller sleeves.
The body 300 has an undercut 310 and the body 400 has a forward projection 410 adapted to fit within the undercut 310 when bodies 300, 400 are mated.
FIGURE 7 illustrates the mating of the conductor assembly 304 mounted to the body 300 with the conductor assembly 404 mounted to the body 400. The conductor assembly 304 includes a housing 305 which fits within a housing 405 of the conductor assembly 404.
Wire strands 306 associated with the assembly 3G4 mate in electri- ~-cal circuit relationship with wire strands 406 associated with the assembly 404.

- ~1234~39 g FIGURE 8 is a partial cross-sectional view of an insulated wire or conductor 500 which has a single central conductor strand 510 surrounded by ;nsulation 520.
FIGURE 9 is a view of the wire 500 of FIGURE 8. The forward S end portion of the wire 500 is cut to an acute angle 0 and the insu-lation has been removed from a forward portion 540. If desired, the rearmost portion may also be prepared in a similar fashion;
however, other methods oF conductor termination might also be em-ployed to advantage. The angle ~ is preferably about 30, although angles as large as 45 might be used to advantage.
FIGURE 10 ;s a view of a plurality of wires 500 held wi~hin a sleeve 550 by crimps 560. The forward end portions 540 each with ~;
an exposed conductor and acutely angled end surfaces, extend be-yond the sleeves 550 at each end of the wires 500.
FIGURE 11 illustrates the use of a plurality of conductors 500, with the insulated medial portion assembled into a multi-conductor cable 570. Preferably, the cable 570 includes a metal conduit which is helically wound to provide a crush-proof, flexible encapsu-lation providing maximum protection for the cable with a minimum outside diameter, to protect against hostile environments. In more controlled environments, the multiple conductors might be assembled into the cable 570 by an electrical tape or other suitable securing ~
material. `
The holder 550 associated with each conductor 500 is mounted to a molded, multi-passage body 580 which has a plurality of parallel passages 581. Associated with each passage is a contact - retention cone 582 which is pcsitioned to secure the holder 550 in place within the passage 581 by engaging one side of an enlarged shoulder 552 of the holder 550- The other side of the shoulder 552 seats against a stop 583 associated with each passage. Such con-tact retention systems are more fully described in u.s. patent ~o. 4,082,-398 of N. C. Bourdon et al entitled "Electrieal Connector Rit'~l Front and Rear Insertable and Removable Contacts". ~.

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A sleeve 590 has been inserted over the other end of one of the conductors 550. The other ends may have si~ilar terminations or a termination chosen from any of the suitable electrical terminations, depending upon the use of the cable 570.
FIGURE 12 illustrates three uninsulated (bare) straight strands 600 of an electrical conductor which, cons;dering both good perfor-mance and low cost, is preferably a high strength stainless steel (hard drawn 303 stainless steel). Other mater;als such as copper-weld-type steel or a carbon steel core, copper clad wire could be used, as could other metals and alloys which have low cost, good conductivity, high strength,-resilient and with friable oxides.
Such additional metals and alloys include berylium copper or other known materials.

The strands 600 have been cut to the desired length and have been cut with an acute angle ~ on the ends. The angle ~ is pre-ferably 30.
FIGURE 13 is a view of one conductor strand 600 coated with an ef~fective amount of an electrically insulating material 610, except in end portions E. The insulating material is preferably magnet wire varnish such as is sold under the trademark Kapton.
FIGURE 14 is a cross-sectional view of the conductor strand 600 showing a thin coating of the insulatir,g 610.
FIGURE 15 is a view of a conductor 700 including a plurality - of conductor strands 600 prepared as described in FIGURES 12-14 and assembled in axial alignment, with end surfaces extending approximately a uniform distance. A sleeve 710 has been inserted `
over the end portions of the plurality of strands 600 and held in place by a radial crimp 711 which secures the wires together in a ~-tight bundle. `~
FIGURE 16 shows a conductor 700 similar to FIGURE 15. At one ;
end of the conductor, a conventional electrical termination 720 rather than a brush-type contact is attached to the conductor 700 either by solcler or a crimp (depending on the application).

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~Z34~9 Additionally, an optional casing 730 of electrically insulating material has been applied around the bundle of wire strands between the sleeve 710 and the termination 720, eliminating in some in-stances the requirement that the individual strands of wire be separately insulated.
FIGURE 17 illustrates a connection of a first conductor 810 with a second conductor 820 in electrical circuit relationship.
The first conductor 810 includes a conventional termination 812, and a plurality of conducting strands 814 which terminate in acutely -~
angled end surfaces 816, held radially together by sleeve 818. The second conductor 820 includes a plurality of conducting strands 824 which terminate in acutely angled end surfaces 826,827 at the re-spective ends. The end surfaces 826,827 are held radially together by sleeves 828,829 respectively. The sleeves 818,828 are held within a housing 830 which is adapted to hold the sleeves so that the end surfaces 816 are mated with the end surfaces 826, with an electrical circuit relationship established between the end surfaces 827 and the termination 812.
Other objects and advantages of the present invention will be apparent to those skilled in the art in view of the foregoing de-scription. The foregoing description accordingly should be considered as illustrative only and should not be interpreted to limit the scope of the present invention, which is defined by the following claims.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electrical cable assembly comprising:
a cable having a plurality of electrical conductors, electrically insulated from each other, each conductor comprised of a plurality of wire strands; and a sleeve mounted on each conductor, said sleeve spaced from one end of said conductor, said wire strands extending from said one end of said sleeve, being axially aligned with each other and the end of each such strand having an acutely angled end surface.

2. An electrical cable assembly of the type described in Claim 1 wherein the sleeve is crimped around the wire strands to secure the sleeve in a predetermined location along the strands and to urge the wire strands together into close contact in the vicinity of the sleeve crimp.

3. An electrical cable assembly of the type described in Claim 1 wherein the wire strands are made of a stainless steel alloy core with an external coating of a material chosen from a group including gold, silver, rubidium, platinum, copper and copper-weld.

4. An electrical cable assembly of the type described in Claim 1 wherein the conductors are insulated from each other by an insulating means which is a magnet-wire varnish.

5. An electrical cable assembly of the type described in Claim 4 wherein the varnish is Kapton.

6. An electrical cable assembly of the type described in Claim 4 wherein the magnet-wire varnish is applied to each wire separately.

7. An electrical cable assembly of the type described in Claim 1 wherein the conductors are insulated by insulating means of rubber or plastic material which surrounds the plurality of electrically-conducting wire strands as a group.

8. An electrical cable assembly of the type described in Claim 1 wherein the wire strands extend from the sleeve in a forward contact region and are mateable with an electrical contact including a plurality of fine wires held together in a bundle, said fine wires each having an acutely angled end portion with said contact region being in contact with the plurality of fine bundled wires and the angled end portions of the contact being within the cable wires and the angled end portions of the cable wires being within the contact wires.

9. A cable of the type described in Claim 2 wherein the sleeve has an external shoulder for being held within a receiving structure.

10. An electrical conductor assembly comprising:
a conductor comprised of a plurality of wire strands;
a terminal at one end; and a sleeve mounted around the wire strands at the other end, said sleeve spaced from said other end to expose a predetermined length of said wire strands; said length of exposed wire strands at said other end being axially aligned with each other and the end of each such strand being angled.

11. A method of forming an integral electrical contact at a forward end of an electrical conductor, the steps of the method comprising:
removing the insulation from the forward portion of the electrical conductor to expose a plurality of strands at the forward end thereof;
straightening and axially aligning the strands;
forming an acutely angled surface at the forward end of each strand; and applying a sleeve around the aligned strands at a location spaced rearwardly from the forward end to maintain the strands in close proximity.

12. An electrical cable assembly comprising:
a cable having a plurality of electrical conductors, electrically insulated from each other, each conductor comprised of a plurality of conducting wire strands serving as a conductor termination for mating; and a sleeve mounted on each conductor for securing each plurality of strands together, said sleeve spaced from one end of said conductor, said wire strands extending through said one end of said sleeve, with said strands being axially aligned with each other in a forward region thereof and the forward end of each such strand having an acutely angled end surface, with said wire strands exposed for mating with another conductor.