US1884432A - Electrical cord terminal - Google Patents

Description

Oct. 25, 1932. A l N, H, WATTS 1,884,432

ELECTRI CAL CORD TERMINAL Filed April 24, 1929 FIE `L FIE E i if l /v/////////Z///////% ///////l INVENTOR /Vob/z H. Wai/f5 A TTORNE YS 60 contact elements of the terminal.

Patented oct. 25, 1932 UNITED STATES PATENT OFFICE NOBLE E. WATTS, OF ALA, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGNMENTS, T GENERAL ELECTRIC COMPANY, 0F SCHENECTADY, NEW YORK, A CORPORATION 0F NEW YORK Application led April 24,

rI'his invention relates generally to the construction of electrical terminals employed for making temporary electrical connection with a complementary connector device. It is intended primarily for use in connection with eXible electric cords.

It is an object of this invention to devise a novel electric terminal of the type having a metallic sleeve contact element, which will 1Q utilize a body made of resilient insulating material, such as vulcanized rubber..

It is a further object of this invention to devise an electric terminal of the female type which will be substantially indestructible and which can be cheaply' and readily manufactured with a minimum number of parts.

It is a further object of this invention to devise a novel construction which will reinforce and prevent crushing of a metallic sleeve contact element, when such element is mounted within a body of resilient material, such as vulcanized rubber.

It is a further object of this invention to make use of a filler to advantage in combina- 2 tion with a female type of electric terminal,

utilizing a body of resilient material.

Further objects of the invention Will appear from the following description in which I have set forth the preferred embodiment 80 of my invention. It is to be understood that the appended claims are to be accorded a range of equivalents consistent with the state of the prior art.

Referring to the drawing:

Figs. 1 and 2 are side and end elevational views respectively, of an electric cord terminal constructed in accordance With my invention.

Fig. 3 is an enlarged side elevational view in, cross section, illustrating the structural details of the preferred form of my electric terminal, the plane of section being taken along the line 3-3 of Fig. 2.

In the past resilient insulating material,

as material for the construction of flexible electric cord terminals. Terminals of this kind have a permanent electrical connection between the cord conductors and the electrical The resuch as vulcanized rubber, has been utilized ELECTRICAL COR-D TERMINAL 1929. Serial No. 357,689.

silient nat-ure of the body prevents injury to 'the contact elements, and generally an extended resilient portion of gradually reduced diameter is employed for precluding abrupt bending of the cord at the point of entrance into the terminal body. When utilizing resilient material in the construction of a female form of terminal, certain problems are involved which are solved to a practical degree by my invention. For example a female terminal necessitates the use of a metallic sleeve contact elementewhich is apt to be crushed by pressure applied to the resilient body. The parts of the terminal must also be'associated in such a manner that the rubber or other resilient material can be readily vulcanized about the assembly, Without causing a certain amount of rubber to extrude into the metallic sleeve contact element. A terminal of this character must also be simple in construction and capable of ready manufacture in order to compete with other forms of cord terminals.

The construction of my improved terminal can best be understood by explaining the manner in which it is manufactured. Referring to Fig. 3, I utilize a metallic sleeve contact element 11, which is made of some material having good electrical conductivity, such as copper. This sleeve is preferably threaded as shown, so as to receive a complementary threaded plug connector -or lamp base. Disposed adjacent the inner end of sleeve 11, there is a central contact element 12 which is intended to cooperate with the central contact of the complementary plug connector. For mounting central contact 12, I employ a member 13 of insulating material such as porcelain, preferably in the form o a small button suitably secured to the adjacent end of sleeve 11. For example I have shown the periphery of button 13 seated Within an annular portion' 14 formed integral with the sleeve 11. Circumferentially spaced indentations 16 serve to lock the-button 13 in fixed relation with respect to sleeve 11. For securing contact elements 12 to the button 13, I have shown a threaded pin 17, engaged by a nut 18.

My terminal is preferably associated with a fiexible electric cord 19, and this cord preferably has conductors 21 enclosed in a suitable resilient casing 22. For example this casing can be of resilient vulcanized rubber. The cord sheath 22 preferably terminates short of the inner end of sleeve 11, and the extended end portion 21a of one of the cord conductors has a suitable weld or soldered connection 24 with sleeve 11. The other extended cord portion 2lb has a soldered or lweld connection 26 with pin 17. In order to preclude undue tension being placed upon the conductor portion 2lb, I prefer that that portion of the conductor adjacent the connection 26, have one or more turns or loops 27 about lthe pin 17. A certain amount of slack can also be provided in the conductor portion 21a.

Before the conductor portion 21a is attached to sleeve 11, I prefer to position a suitable filler at the inner end of sleeve 11. This filler is preferably fiexible to a certain degree, that is it should be capable of deforming or bending without breaking. For this purpose I have found that it is satisfactory to utilize a lurality of turns of linen or cotton tape 29 a out the conductor portion 21?) and pin 17 and adjacent the inner face of button 13.

Before ap lying the body of resilient material, I pre er to position a sleeve 31 about the outer periphery of the metallic sleeve 11. This sleeve 31 is made of insulating material and is preferably substantially rigid. Its outer edge 32 extends a substantial distance beyond the outer edge of sleeve 11. A convenientway to form the sleeve 31 is to wrap a plurality of turns of suitable fibrous material about the metallic sleeve 11. This fibrous material should be impregnated with a suitable gum, such as a phenolic condensate product, to add rigidity and strength. For example I have secured good results by applying a plurality of turns of what is known as leatheroid paper, which has been dipped ink a phenolic condensate gum. When applied in this manner, sleeve 31 is securely bound and anchored to the metallic sleeve 11. To secure effective bonding to the material of the body I preferably provide a ring surrounding the outer end portion of sleeve 31. This ring is formed of a metal 'which will bond to vulcanized rubber. For

example it can be formed of a plurality of turns of brass wire.

After the completion of the above described assembly, a body of suitable resilient insulating material is molded or formed about the same. A satisfactory material is uncured rubber, such as is used in the manufacture or repair of automobile tires. I have found it convenient to utilize a ribbon of this rubber, and to wrap this ribbon about the assembly. After one or more layers of this ribbon has been applied, the assembly is preferably wrapped with a reinforcing cord 33, after which the remainder of the rubber is applied. The entire structure is then placed in a suitable mold, and vulcanized by heat under considerable pressure. Preferably the rubber is applied in such a manner and the mold is shaped so that the rubber forms one portion 34 which siirrounds the metallic sleeve 11 and insulating sleeve 31, and another integral portion 36 which is of gradually reduced diameter and which surrounds and is bonded to the advance end of the flexible cord 19.

After the vulcanizing operation, it will be found that the rubber has been bonded to the metal ring 30 and closely surrounds the outer periphery of insulating sleeve 31, while the portion 36 of reduced diameter has a vulcanized bond with the rubber sheath 22 of the flexible cord 19. The rigid sleeve 31 prevents the rubber of the body from flowing into the interior of sleeve 11, during the vulcanizing operation, and likewise the filler tape 29 prevents the conductor portions 21a and 2lb from being forced into direct physical contact.

Since the outer end of the metallic sleeve 11 is set back a substantial distance from the front face 38 of the body, portion 39 of the body together with the corresponding portion of sleeve 31 forms an insulating shroud tending to prevent accidental contact with the metallic sleeve 11. This shroud also increases the leakage distance between sleeve 11 and a metallic band of a lamp guard or like device which may be placed about the terminal body. Altho all the exposed outer surfaces of the terminal are of resilient material to absorb shocks and blows, therefore tending to preclude accidental injury, the shroud portion 39is reinforced because of the relatively riga'd insulating sleeve 31. Furthermore sleeve 31 materially reinforces the metallic sleeve 11, and thus the likelihood of deformation or crushing of metallic sleeve 11 due to lateral pressure applied to the terminal, is minimized. When the cord near the terminal is bent to one side, portion 36 prevents an abrupt bend of the cord near the terminal, and thus precludes breakage of the conductors and the connections of the conductors to sleeve 11 and central contact 12. When the body of the terminal is bent or deformed a certain amount, filler 29 vcan also 've to a certain extent, so that there is no anger of mechanical breakage of the insulation between conductor portions 21a and 2lb.

I claim:

1. In an electrical terminal, a body of resilient rubber, a metallic sleeve positioned within said body, the interior of the sleeve being accessible for electrical contact thru one face of said body, and gum impregnated fibrous material imposed between said sleeve and the rubber of said body.

2. In an electrical terminal, a body of re. silient material a metallic sleeve contact set within said boy, the interior of the sleeve being accessible for electrical contact thru one face of said body, said face of the body extending beyond the adjacent end portion of the sleeve to form a shroud, and means in addition to the resilient material of the sleeve for st-iiening said shroud.

3. In a female electrical terminal for a flexible electric cord, a metallic sleeve contact element, a relatively rigid sleeve of insulating material surrounding said metallic sleeve and extending for a substantial distance beyond one end of the metallic sleeve, a'central ccntact element insulated from the sleeve element, an electric cord having conductors thereof connected t0 said elements, a resilient filler disposed adjacent the other end of the metallic sleeve, and a body of resilient insulat ing material molded to and about said'rigid sleeve and surrounding said filler and the adjacent portion of said cord.

In testimony whereof, I have hereunto set 25 my hand.

NOBLE H. WATTS.

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