US3444507A - Electrical connectors for semi-solid conductors - Google Patents

Description

S. GERHARD May 13, 1969 ELECTRICAL CONNECTORS FOR SEMI-SOLID CONDUCTORS Filed Oct. 23, 1967 INVENTOR.

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ARD L ATTORNEY United States Patent 0.

3,444,507 ELECTRICAL CONNECTORS FOR SEMI-SOLID 'CONDUCTORS Sidney Gerhard, Norwalk, Conn., assignor to Burndy Corporation, a corporation of New York Filed Oct. 23, 1967, Ser. No. 677,292 Int. Cl. H01r 11/20, 3/02, 15/12 US. Cl. 339-100 6 Claims ABSTRACT OF THE DISCLOSURE An electric terminal connector, for electrical cable of the type which has a central core of highly ductile metal enclosed within an outer insulating jacket, in which a fixed portion of the connector is secured to the cable jacket and hydraulic pressure is employed to displace a pistonlike contact element relative to the fixed portion so as to urge the contact into engagement with the ductile metal core of the cable.

This invention relates to electrical connections and connectors, and has the general object of providing a simple, sturdy, and effective means for establishing reliable electrical connections to electrical cables of an unusual type.

The insulated electrical cable contemplated for use with this invention comprises a core of highly ductile conductive material such as sodium, encased within a tubular insulating jacket of strong, flexible material such as commercially available polyethelene.

Sodium conductor cables are of significant interest to the electrical power industry because the metal oflt'ers electrical characteristics favorably comparable to the more commonly used copper and aluminum conductors at substantially less cost. It is known, however, that certain other physical characteristics of sodium, and similar conductive metals, differ substantially from those of the standard cable conductors.

It has been found that the previously known connection and construction techniques for electrical cable c onductors do not operate effectively with a conductor which cannot be welded, soldered, or physically clamped in any practical manner. Connections to cables of the sodium conductor type are further complicated by the necessity for protecting the conductor from exposure to air, water, and other reactive elements.

Accordingly, it is an object of this invention to provide an electrical connection which effectively seals the exposed end of a cable to which it is applied, against exposure to reactive elements.

A further object of this invention is the provision of an electrical connector which employs force-multiplying means for assuring positive engagement of a contact memher with the central conductor of an electrical cable. Other objects of this invention are directed generally toward providing reliable, inexpensive, and easily applied connectors and connection techniques for establishing secure electrical and mechanical contact with electrical cables having conductors formed of realctive and/tor ductile materials.

Features of this invention include the use of an outer bod-y member which can be secured to the insulating jacket of a cable and which includes an inner cylinder portion, in combination with a piston-like contact element forming an expansible chamber within the cylinder portion of the body member, such that hydraulic pressure may be applied within the chamber to urge the contact member into engagement with the cable conductor.

These and. other objects, features, and advantages of this invention will be distinctly and specifically pointed out in the accompanying claims and will be more fully 3,444,507 Patented May 13, 1969 disclosed and explained in the following specification, in conjunction with the accompanying drawings, inwhich;

FIG. 1 is a partially-exploded, longitudinal-section view of a connector constructed in accordance with this invention, shown in axial alignment with the end of an electrical cable;

FIG. 2 is a partially-sectioned longitudinal elevation view of the connector of FIG. 1 shown in assembled position; and

FIG. 3 is a fully sectioned view of the assembled connector of FIG. 1, shown coupled to the end of an electrical cable.

Referring now more specifically to the drawings, the connector of this invention, as shown in FIG. 1, may be seen to comprise an outer body member, indicated generally by reference numeral 10 and including an inner cylinder portion 12, and a central conductive contact member 14 which is adapted to have a piston-ring assembly 16 secured thereto by means of snap-ring 18. The assembled relationship of the elements of the connector are shown more clearly in FIG. 2. Piston-ring assembly 16 may be seen to comprise a circular ring element 20, formed of any suitable structural material, and an outer sealing washer 22 mounted in the outer periphery of ring 20.

As seen in FIG. 2, body member 10 includes an endopening 24 which opens into inner cylinder 12. A sealing washer 26 is disposed within a reduced diameter portion 28 of body member -10 to form a sliding-seal engagement with the main body portion 30 of contact element 14. The contact element is, in turn, provided with a forward contact portion 32 which may be pointed as at 34 to facilitate penetration into the central core conductor of a cable of the type described. A shoulder 36 is formed on the contact element between body portion 30 and contact portion 32; and a retaining-ring groove 38 is formed in portion 32, spaced axially from shoulder 36. Piston-ring assembly 16 is captured to contact 14 by slipping the assembly over contact portion 32 until ring 20 abuts against shoulder 36; locking-ring 18 is then slipped over portion 32 until it snaps into groove 38, thereby capturing assembly 16 between itself and shoulder 36.

Contact element 14 includes extending tail portion 40 which is disposed externally of the body portion 10. In use, tail portion 40 may be given any suitable configuration for establishing electrical connections between contact element 14 and external electrical conductors. Pistonring assembly 16 is formed separately of contact 14 to permit the connector to be assembled by slipping forward end portion 32 of the contact element through sealing washer 26 when the transverse dimension of tail portion 40 is greater than the diameter of sealing washer 26. It is considered obvious, however, that alternate means may be employed to provide the contact element 14 with a tail portion 40 and with a piston-ring assembly 16, without departing from the concepts and scope of this invention.

When the elements of the connector have been assembled together as described above, sealing washer 26 and piston-ring assembly 16 form, between them, an expansible chamber 42 bounded by the inner wall of cylinder 12 and the main body portion 30 of contact 14. An inlet fitting 44, which includes central inlet passage 46, is mounted in the wall of body member 10 to provide access to expansible chamber 42 from the exterior of the connector. Hydraulic fitting 44 is preferably of the one-way valve type, characterized by a ball valve 48, which is adapted to permit passage of hydraulic fluid material in one direction only (into chamber 42) through inlet passage 46. By means of inlet passage 46, therefore, it is possible to introduce flowable fluid material into expansible chamber 42. Introduction of the fluid, under pressure, will displace contact element 14 relative to body member fnom the position shown in FIG. 2 to the relative position shown in FIG. 3. The fluids contemplated for use in this application include greases, liquid rubbers, and hardenable materials, such as epoxies and the like, in addition to the more conventional hydraulic pressure fluids. The use and advantages of this feature will be made apparent below.

The end of body member 10 which is remote from sealing washer 26 is provided with an internally foamed helical SCICIW thread 50. This threaded portion is adapted to receive the outer diameter of an electrical cable such as 52, in threaded relationship. As shown most clearly in FIG. 1, cable 52 includes an outer jacket 54 of insulating material which surrounds a central core 56 of highly ductile, conductive metal. Screw threads 50 are self-tapping in nature, and are designed to engage and cut a mating helical-thread into the outer surface of cable jacket 54. To facilitate threaded engagement of the body member with the cable, the outer surface of the body member is provided with a series of fiat surfaces, such as 58, in the manner of the well-known wrench-flats on a standard nut and bolt. An ordinary mechanics wrench may thus be used to facilitate application of body member 10 to the end of a conductor 52 with sufficient force to securely fasten the two together. The interior of body member 10 may be provided with a cable-strap shoulder 60 at one end of cylinder 12 as a means for assuring that a sufficient length of the cable jacket 54 will enter the connector as the body member 10 is threaded onto the cable jacket.

The connector of this invention, which has been described thus far, is secured to an electrical cable to form a terminal connection as follows: with contact element 14 in the retracted position relative to body member 10, as shown in FIG. 2, the threaded portion 50 of the body member is engaged to the insulating jacket 54 of a cable 52, by hand or by means of a wrench applied to wrench-flats 58. After the body member has been securely fastened to the cable jacket, a source of hydraulic material is coupled to inlet fitting 44 and hydraulic material 49 is pumped into expansible chamber 44 until con tact element 14 has been displaced from the position shown in FIG. 2 to the position shown in FIG. 3. The contact and body member are relatively dimensioned so that in its forward-most position, forward contact portion 32 of contact element 14 is embedded within the highly ductile central conductive core 56 of cable 52. Embedding of the contact portion has been found to be necessary to break through the high resistance film which forms at the cut end of a cable due to reaction of the sodium with airborne water vapor. The pressure applied to hydraulic material 49 in filling expansible chamber 42 assures penetration of the care by the conductive element.

As the contact element penetrates the core, a portion of the core material will be displaced unavoidably beyond the end of the cable jacket 54, as shown in FIG. 3. Air displaced by the core material and by the moving contact element is vented through outlet ports 64. Bypass passages 62, which are provided within the body 10 between cylinder 12 and annular chamber 71, are a feature of this invention which permit the use of hydraulic material 49 to prevent escape of the displaced core material. Use of the hydraulic material in this manner also prevents further contact of the core material with air, water vapor and water which may be present outside the body 10.

As shown in FIG. 3, the by-pass passage operate, when contact element 14 is in its forward-most position, to permit escape of hydraulic material 49 from chamber 42 past piston-ring assembly 16 and into contact with the exposed core material. As the flowable hydraulic material is pumped into chamber 42, by-pass passages 62 and annular chamber 71 become filled, thereby completely surrounding the core material and a portion of the cable jacket 54. A plurality of outlet ports 64 are provided through the wall of body member 10 to permit limit escape of material 49 after the material has completely filled annular chamber 71.

The several outlet ports 64 permit the venting of air from within the connector assembly regardless of the attitude or position of the connector. Additionally, they provide a convenient external visual indication that the connector has been sealed, by material 49, against escape of core material 56 and against entry of air, water and water vapor into body 10.

A further feature of this invention is the provision of additional means for locking contact element 14 in the advanced position shown in FIG. 3. This locking means includes resilient detent locking-ring 66, which is secured to body member 10 by means of a retention washer 68 positioned within an annular groove 69 in body member opening 24. Locking-ring 66, which is canted inwardly in the direction of advancement of contact element 14, interengages with locking groove 70 in the contact element, to prevent rearward movement of the contact after it has reached the forward-most position shown. The use of this detent means may replace or supplement the retention achieved by the use of a hardenable or settable hydraulic fluid.

This invention has now been described, but it is desired to be understood that it is not confined to the particular forms or usages herein set forth for the purpose of illustration, and that the invention may be carried out in other ways without departing from the spirit or scope of the invention; therefore, equivalent instrumentalities may be employed by means of which objects of this invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to obtain these objects and accomplish these results.

I claim:

1. An electrical connector, adapted to be electrically coupled to the end of an electrical cable which has a homogeneous central core of highly ductile metal enclosed within a substantially tubular insulating jacket, said connector comprising:

an outer body member having a substantially central cylinder portion therein;

a central conductive contact member having a piston portion telescopically disposed within said central cylinder portion, defining an expansible chamber within said body member;

means on said body member for securing said body member to the insulating jacket of an electrical cable in coaxial relationship;

means on said body member for introducing flowable hydraulic material into the said expansible chamber, under pressure, to displace said piston portion relative to said cylinder portion;

a contacting portion on said contact member, extending from said piston portion, for engaging the conductor of an electrical cable secured to said body member upon displacement of said piston portion relative to said body member;

external connection means on said contact member disposed externally of said expansible chamber for establishing electrical connections therewith.

2. The electrical connector of claim 1 wherein said means to secure said outer body member to the insulating jacket of an electrical cable comprises an internally threaded cylindrical portion capable of engaging the outer surface of the insulating jacket in threaded relationship.

3. The electrical connector of claim 1 wherein the piston portion on said contact member comprises a piston ring, detachably coupled to said contact member, which forms a radially extending annular projection on the contact member.

4. The electrical connector of claim 1 further including a by-pass portion within said cylinder portion, located so as to permit fiowable material from said expansible chamber to escape past said piston portion of said contact member when the expansible chamber has been expanded to a predetermined position of the piston.

5. An electrical connector in accordance with claim 4 further including an outlet port extending through the wall of said body member from said by-pass portion to the exterior of said body member, permitting escape of the flowable material to evidence passage of said material through said by-pass portion.

6. The electrical connector of claim 1 further including cooperating detent means on said contact member and on said body member, adapted to interengage and lock References Cited UNITED STATES PATENTS 7/1962 Honig 339116 X 3/1965 Henschke 339-100 X 10/1966 Council 3391 17 X 10/ 1967 McNerney 174-77 2/ 1968 Harris et a1 17475 RICHARD E. MOORE, Primary Examiner.

US. Cl. X.R.

when said contact member has been displaced to a given 15 17477; 339116, 223

position relative to said body member.

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