US2823250A - Insulated closed end connector - Google Patents

Description

M. F. O'KEEFE INSULATED CLOSED END CONNECTOR Filed Feb. 17, 1955 FeBfI'l', 1958 INVENTOR,

M ichaei F. O'Keefe United States IPatent O INSULATED CLOSED END CONNECTOR Michael F. OKeefe, Mechanicsburg, Pa., assignor to AMP Incorporated, a corporationl of New Jersey Application February 17', 1955, Serial No. 488,758` 3.Claims. (Cl. 174-87)- An object of this invention is to provide a fully insulated connector for connecting a plurality of wires. One method of joining such wires is to insert the bare ends of the wires into a common opening in an insulated tubular connector and to crimp the connector, thereby securing it to the wires and joining the wires together in an electrical engagement.

In order to comply with the specifications of the Underwriters Laboratory the connection is subjected to the following test conditions: (l) A three pound weight is suspended from one of the wires in the connector, and the other wire is attached to a motor which rotates the suspended weight for two hours to determine the secureness of the connection. (2) A direct pull of thirty pounds is placed on the wires for one minute. (3) A dielectric strength test whereby the connector is immersed in lead shot to cover the outer surface of the connector, then 2,200 volts A. C. is applied for one minute. If the insulation punctures or flash-over occurs, the connector fails this test. (4) To test secureness of insulation the connector shall not become detached from the body when a thirty pound pull is applied. Tearing or breaking of the insulation constitutes damage if the connector is adversely aiected when retested for dielectric strength.

It has been noted that the connectors presently in use may sometimes fail by reason of a tearing of the insulation when the pull test is applied. Even though the wires may not be pulled apart or separated from each other, it is obvious that such a tearing of the insulation will cause the connection to fail the dielectric strength test when subsequently applied.

Thus it is an object of this invention to provide a connector that will withstand heavy test loads as applied according to the Underwriters Laboratory specifications.

It is also an object of this invention to provide a connector Ifor connecting together a plurality of wires whereby the connector will be bound more tightly on the wires when two wires entering a common wire-receiving opening are pulled in opposite directions.

Other important features and objects of the invention to which reference has not been made hereinabove will appear hereinafter when the following description and claims are considered with the accompanying drawings, in which:

Figure l is a perspective view of one embodiment of the improved connector;

Figure 2 i-s a perspective view of the improved connector with the wires crimped in place;

Figure 3 is a longitudinal section through the connector of Figure l, taken along lines 3 3;

Figure 4 is a longitudinal section through lines 4 4 of Figure 2;

Figure 5 is a view partly in section showing the improved connector of Figures 1-4 with the wires crimped in place, after a heavy test load has been applied;

Figure 6 shows a view of a type of connector previously used, demonstrating how the connector failed to withstand a heavy load when subjected to the pull test; and

Figure 7 is a view similar to Figure. 5, showing thev connector after a heavy test load has been applied.

A particular form of the invention asv illustrated in Figures 1-5 includes a closed end plate 2. The particular end plate 2 shown in the drawings constitutes what is known as a 3-in type of'closure. However, it is obvious that any type of etlcient closing means can be used. The end plate closes one end ofa tubular. portion 4 and an enlarged tubular portion 6 emanates from the first tubular portion. This lower portion forms ra skirt or sheathforY envelopingand supporting the inserted wires: 8, 10. A metal tubular member 12 acts as a conductor and seats within the rst tubular portion 4. The juncture of the two tubular portions is indented or necked-in as shown at 14.

In the preferred embodiment the connector is formed from a strip of flexible tubular insulating material of a substantially constant thickness. While the tubing is in a pliable state, one end is enlarged to form the sheath 6. The ends of the connector are then pressed between two surfaces, to form the necked-in portion 14 and the unenlarged portion is sealed with the type of closure shown. Of course other methods of manufacturing the connectors may be employed.

The preferred embodiment as shown and described is made from tubing having an outside diameter of .288 and a thickness of approximately .025". This tubing is cut into 1.042 sections and the sheath is enlarged to an outside diameter of .425. The indented portion has an inside diameter of .196 and a .139 height. The unenlarged portion has a height of .570 and the enlarged portion has a height of .273". Of course these dimensions are merely illustrative and variations will be obvious to anyone skilled in the art. The only condition which is critical is that the relationship of parts be such that the enlarged tubular portion will telescope over the closed tubular portion when a pull is exerted on the wires.

In operation the stripped ends of the wires are inserted through the open enlarged portion 6, past the indented portion 14 and into the metal tube 12. Then the metal tube and the insulation surrounding it are crimped to unite the wire ends (see Figures 2 and 4) thus forming an efficient electrical connection and also binding the insulating connector to the wires. When a force is exerted upon the respective wires in opposite directions, at a right angle to the longitudinal axis of the connector, as required by the Underwriters Laboratory tests, the particular type of connection shown and described will withstand greater stresses than connectors now in use. This is due to the fact that, in the connectors now in use, a pull exerted upon the wires causes the wires to cam against the lower part of the connector and exert a force directly on the lower edge 16 of the connector sheath thus tending to rupture it as shown in Figure 6. Even though such stresses do not pull the wires from the connector, a rip in the edge of the skirt materially reduces the Hash-over performance of the terminal and renders it unsatisfactory for passing test specifications. However by placing an indention 6 at the base of the upper portion 4 (as shown and described), a lateral pull on the wires causes the upward force on the lower edge 16 of the sheath to collapse the indented portion and allow the lower portion to telescope upwardly over the upper portion, as shown in Figures 5 and 7 thus preventing the lower portion from tearing. This telescopic action also causes the insulating material in the neighborhood of the necked-in portion to become constricted at the base of the metal portion and reduces the inner insulation diameter. This causes the insulation to bind the metal tube and effects a snug fitting between the metal tube and the insulation which increases the amount of force required to withdraw the metal tube (and thus the wires) from the insulation.

Changes in construction will occur to those skilled in Patented Feb. 11, 1958- vention is intended to be defined in the following claims when viewed in art. i

I claim: l. An improved insulated electrical connector for connecting a plurality of wires, comprising a first tubular inthei-r proper perspective against the prior -sulating portion having one closed end and one open end, a secondrexible, enlarged, tubular insulating portion emanating from the open end of said first tubular portion,

the junction of the tubular portions being indented so that 15 4 the outside diameter of said indented portion is smaller than the outside diameter of said rst tubular portion.

2. The device as set forth in claim l, including a metal ferrule within the rst tubular insulating portion.

3. The device as set forth in claim 2, wherein the metal `ferrule is confined within the rst tubular insulating portion between the indentation and the closed end of the rst tubular portion.

References Cited in the le of this patent vUNITED STATES PATENTS 2,037,630 Hudson Apr. 14, 1936 2,618,684 Bergan Nov. 1s, 1952 2,701,273 Badeau Feb. 1, 1955

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