US3631382A

US3631382A - Electrical connector

Info

Publication number: US3631382A
Application number: US24224A
Authority: US
Inventors: Charles D Baker
Original assignee: National Aeronautics and Space Administration NASA
Current assignee: National Aeronautics and Space Administration NASA
Priority date: 1970-03-31
Filing date: 1970-03-31
Publication date: 1971-12-28
Anticipated expiration: 1988-12-28

Abstract

A sterilizable electrical connector which readily can be inspected after sterilization characterized by a flexible multistrand conductor coupled with a barrel-and-lug terminal element, a feature of the connector being an elastomer disposed within the barrel and securing an end of the conductor therewithin while the distal end of the conductor is secured to the exterior of the barrel through a circumscribing and deformed ferrule.

Description

llnited States aten [72] Inventors Thomas 0. Paine Administrator oi the National Aeronautim and Space Administration with respect to an invention of; Charles D. Baker, La Canada, Calif.

[21] Appl. No. 24,224

[22] Filed Mar. 31, 1970 [45] Patented Dec. 28, 2971 [S4] ELECTRICAL CONNECTOR 5 Claims, 8 Drawing Figs.

[52] U.S.Cl 339/275 T, 339/276 T [51] Int. Cl ..H0lr 11/06,

HOlr 11/08 H [50] Field 01 Search 3391275;-

[56] References Cited UNITED STATES PATENTS 3,383,457 5/1968 Schumacher et a1. 339/276 2,163,771 6/1939 Alden 339/275 2,393,355 1/1946 Eppler et al. 339/276 2,749,420 6/1956 Pityo 339/275 T FOREIGN PATENTS 169,978 6/1951 Germany 339/276 T Primary Examiner-Joseph H. McGlynn Attorneys-G. T. McCoy, J. H. Warden and Monte F. Mott ABSTRACT: A sterilizable electrical connector which readily can be inspected after sterilization characterized by a flexible fmultistrand conductor coupled with a barrel-and-lug terminal element, a feature of the connector being an elastomer disposed within the barrel and securing an end of the conductor therewithin while the distal end of the conductor is secured to the exterior of the barrel through a circumscribing and deformed ferrule.

PATENTEB DEC28 I971 m m s CHARLES 0. BAKE/P INVENTOR 4 Wank- .WKAW

ATTOP/VEKT 1 ELECTRICAL couuacron Origin of the Invention The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 U.S.C. 2457).

BACKGROUND OF THE INVENTION 1 Field of the invention The present invention relates to electrical connectors and methods of fabricating the same, and more particularly to a novel connector including a flexible multistrand conductor and a barrel-and-lug-type of terminal element which is particularly useful in applications in which an electrical connection is to be sterilized by the application of heat, and thereafter visually inspected for reliability.

2. Description of the Prior Art Various types of connectors have heretofore been employed. Such connectors often include solderless connector elements, such as that disclosed by the U.S. Pat. to Canfield No. 2,968,691, utilized as terminals for multistrand flexible conductors. However, these elements have not been found to be entirely satisfactory for applications in which sterilization through heating is required, because the heating and subsequent cooling of the connection, incident to a normal sterilization process, tends to render such devices unreliable. On the other hand, connectors employing soldered connector elements such as that of the U5. Pat. to Sherlock No. 3,324,230, are subject to the risk of loosening of the soldered joint in the event of overheating.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the instant invention to provide an improved electrical connector which substantially is free of the noted defects of the connectors heretofore provided for use in an environment wherein sterilization is required.

Another object is to provide an improved method for fabricating electrical connectors.

Another object is to provide an electrical connector having a soldered coupling established between a flexible, multistrand electrical conductor and a terminal element at an area isolated from mechanical stress inducing forces.

Another object is to provide an improved electrical connector including a flexible electrical conductor coupled with a terminal element in a manner such that the connector is rendered both mechanically and electrically reliable.

These and other objects and advantages of the instant invention are achieved by a method and a device wherein a ter minal element electrically is coupled with a flexible conductor through a soldered connection and mechanically coupled therewith through a collapsed ferrule and an elastomer. The soldered connection is located at a point isolated from stressinducing forces by the elastomer and the ferrule so that mechanical strain incident to relative movement of the conductor and terminal is effectively precluded while the soldered connection is located at a point readily accessible for visual inspection.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective of connections embodying the present invention disposed at opposite ends of a multistrand conductor in the form of a cable.

FIG. 2 is a view in vertical cross section of a lug-and-barreltype terminal juxtaposed with a multistrand conductor in the first step of fabricating a connection according to the present invention.

FIG. 3 is an end view of the configuration illustrated in FIG. 2 with the cable illustrated in vertical section.

FIG. 4 is a view corresponding to FIG. 2 with the ferrule added to the assembly.

FIG. 5 is a view corresponding to FIG. 3 with the ferrule added to the assembly.

FIG. 6 is a view corresponding to FIG. 4 with the ferrule swaged to clamp the conductor.

FIG. 7 is a view corresponding to FIG. 5 illustrating the swaging of the ferrule.

FIG. 8 is a view in vertical section of the completed assembly embodying the present invention illustrating the barrel of the terminal substantially filled with an elastomer embedding the connector and the swaged ferrule, conductor end and barrel of the terminal-soldered together.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views there is depicted in FIG. I a connector 10 fabricated according to the principles of the present invention. As shown, an electrical terminal embodying the present invention is fabricated by first passing a free end I I of a multistrand electrical conductor 12 composed of a bundle of conductors which may be twisted, braided or woven together, through a barrel opening 14 of a barrel-and-lug terminal element l6. The element 16 includes a lug portion 18 adapted for connection, as by bolting, to a battery post or the like, and a barrel portion 20 defining the opening 14. The end 11 of the conductor 12 is reversely directed and then disposed in a position in which it is in a contiguous relationship with the exterior surface of the barrel portion 20 of the terminal element 16.

As shown in FIGS. 4 and 5, a collapsible metal ferrule 22 is positioned in a circumscribing relationship with both the barrel portion 20 of the terminal element 16 and the end 11 of the conductor 12 whereupon it is collapsed, preferably by swaging into a polygonal configuration. As the ferrule is collapsed it is caused to closely embrace the barrel portion 20 of the terminal element 16 and compresses the end 11 of the conductor 12 closely against the exterior surface of the barrel portion 20, thus effecting amechanically strong connection between the conductor 12 and the terminal element 16.

Electrical reliability of this connection is assured by applying metal 24, in its liquid phase, at an area 25 so that it permeates the end 11 of the multistrand conductor 12. The metal 24 ultimately solidifies establishing a permanent electrical contact between the surface of the barrel portion 20, of the terminal element 16, and the ferrule 22. A soft solder has, in most instances, been found to be quite satisfactory for this purpose. However, where preferred, hard solders or even brazing can be employed for use in environments in which very high temperatures are expected to be encountered. The term solder," as used herein, is intended to apply generically to all such applications of metals in the liquid phase.

As desired, either before or after the application of the metal 24, the opening 14 of the barrel portion 20 is substantially filled with a curable fluidized plastic material 26 which, when cured, serves to embed the conductor 12 within the opening. Consequently, an electrical connection is established between the conductor end 11 and the terminal element 16 which substantially is isolated from mechanical stress initiated in response to relative movement of the conductor 12 and the terminal element 16.

The material employed for purposes of embedding the conductor preferably is an elastomer such as polyurethane commercially available from the Thiokol Chemical Corporation under the designation CastroF or Solithane l 13." Such elastomers possess good damping qualities and act to restrain the multistrand conductor substantially without reducing its inherent flexibility, while being sufficiently flexible to prevent sharp bending of the strands of the conductor at the points at which they enter the elastomer.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

3 4 What is claimed is: distal end portion; 1. A method of fabricating an electrical connector including B. a terminal element including a barrel receiving said distal a flexible multistrand conductor and a terminal element havend portion of said conductor in a manner such that the inglug-and-barrel portions, the steps of: distal end portion of said conductor is axially extended A. passing an end of a flexible conductor through a barrel 5 through said barrel and reversely folded into engagement portion of a tenninal element and into juxtaposition with i the external SurfaCe 0f t barrel; the exterior thereof; C. a deformed ferrule circumscribing said barrel and fric- B. swaging a ferrule over the exterior of said barrel portion tionally engaging Said distal end of said Conductor for d id d flh conductor d; d thereby fixedly securing said conductor to said barrel; C. soldering together said ferrule, said conductor end and to and i b l ni D. means including solder forming an electrical coupling 2. The method of claim 1 further comprising the step of subbetween f dfstal end P ofsald cohductof Said stantially filling the interior of said barrel with an elastomer barrel apPhed a thahhet h that the solder Isolated for embedding therein a portion of said conductor. from tehshe Stress applied to Sald conductor- 3. The method of claim 2 in which elastomer is introduced The connector of claim 4 further comprising an elastic into the interior of the barrel portion of the terminal element matrix substantially ffmng s aid barrel P terminal in fluid form element for embedding said end portion of said conductor 4. An electrical connector comprising: within Said barrel- A. a flexible, multistrand electrical conductor having a

Claims

1. A method of fabricating an electrical connector including a flexible multistrand conductor and a terminal element having lugand-barrel portions, the steps of: A. passing an end of a flexible conductor through a barrel portion of a terminal element and into juxtaposition with the exterior thereof; B. swaging a ferrule over the exterior of said barrel portion and said end of the conductor end; and C. soldering together said ferrule, said conductor end and said barrel portion.

2. The method of claim 1 further comprising the step of substantially filling the interior of said barrel with an elastomer for embedding therein a portion of said conductor.

3. The method of claim 2 in which elastomer is introduced into the interior of the barrel portion of the terminal element in fluid form.

4. An electrical connector comprising: A. a flexible, multistrand electrical conductor having a distal end portion; B. a terminal element including a barrel receiving said distal end portion of said conductor in a manner such that the distal end portion of said conductor is axially extended through said barrel and reversely folded into engagement with the external surface of the barrel; C. a deformed ferrule circumscribing said barrel and frictionally engaging said distal end of said conductor for thereby fixedly securing said conductor to said barrel; and D. means including solder forming an electrical coupling between said distal end portion of said conductor and said barrel applied in a manner such that the solder is isolated from tensile stress applied to said conductor.

5. The connector of claim 4 further comprising an elastic matrix substantially filling said barrel portion of said terminal element for embedding said end portion of said conductor within said barrel.