US1739019A - Electric connection - Google Patents

Description

Dec. 10, 1929. H, E, S ITH 1, 35019 ELECTRIC CONNECTION Filed Jan. 10, 1924 2 Sheets-Sheet 1 Harold E7220 5m 11% W [zzvgnfor Dec. 10, 1929. SMITH 1,739,019

ELECTRIC CONNECTION Filed Jan. 10, 1924 2 Sheets-Sheet 2 W HarOZd 51 220 52211 51 in uezizor Attorn eys.

Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE ELECTRIC CONNECTION Application filed. January 10, 1924. Serial No. 685,327.

This invention relates to electric connections and has particular reference to the fittings carried by the ends of flexible conductors sometimes called cords and intended for attachment to lamp sockets, base receptacles, wallbrackcts and other screw threaded outlets. The primary objects of the invention are the provision of a cheap, simple, and reliable device which can be insorted into and withdrawn from an ordinary threaded socket by a substantially direct pull and requiring at most not more than a fractional turn to tighten and loosen. Numerous connectors are known which are attached and t5 detached by a direct pull, but these are mostly of a specialized nature, while lamp bulbs are generally made with screw sockets. Domestic electric appliances such as cleaners, toasters, sad irons, curling tongs, heaters,

portable lamps, motors, fans, etc. are generally furnished with screw plugs adapted for attachment to lamp sockets and, one of the gravest inconveniences in their use is the necessary slow screwing into and out of those sockets with the accompanying twisting and kinking of the cords. Other objects of the invention are the provision of a device of this character which shall not be easily detached by pulling the cord, which shall have a minimum number of loose and movable parts,

and which shall be trouble proof and nonbreakable; while further objects and advantages Will appear as the description proceeds.

Une of the chief features of my invention is the use of a soft flexible composition such as soft rubber for holding the relatively movable parts of the device and thus dispensin with the need of small fastening parts. Thls soft material may comprise the entire body of the socket or only those parts and regions which require to yield or change their positions and the contact members may be either molded permanently therein or fastened rnechanically thereto. Also the conductor wires or cord can either be molded into the composition or attached mechanically, depending upon circumstances. For the composition ll prefer soft rubber cured at such time and temperature and with such small amounts of sulphur and other ingredients as are well known 1n the arts for wringer rolls,

.cushion tires, rubber stoppers and the like,

although certain oils can be vulcanized to a very satisfactory consistency for this purpose.

In the drawings accompanying and form-' ing a part of this application l have shown certain physical forms in which my ideas can be embodied, although it will be understood that these drawings are intended to be merely illustrative of the general features of my invention rather than exhaustive of particular designs' Fig. 1 is a longitudinal section and F ig. 2 a transverse section of a preferred form of cord terminal embodying my improvements; Fig. 8 is a side elevation of one of the metal contact parts; Fig. 4 is a longitudinal detail view showinga modified form of end contact; Fig. 5 is a longitudinal sectional view of another desirable form of my invention; Fig. 6 is a front elevation of the same. Fig. 7 shows a slight modification of the device shown in 5 and 6; F ig. 8 is a longitudinal sectional view and Fig. 9 a cross section of another modification; Fig. 10 is a separated perspective view of the different metal parts thereof; Figs. 11 and 12 are illustrations of still other modified forms;

and Fig. 13 is a sectional view of atypical form of lamp socket for which my improved terminal is designed.

In Figs. 1 to 6 inclusive 1 have shown a cord terminal having a unitary body made Wholly of the soft material mentioned, the flexible conductor being permanently attached thereto and in Figs. 7 to 10 inclusive I have shown the body only as made of this material, the flexible conductor being detachably secured; while Figs. 11 and 12 illustrate portion 2 are a plurality of lateral contact members 55. In the present embodiment these contact members are three in number,

- at 10 in Figs. 1 and 2 between adjacent lateral members.

The flexible cord 12 may be of any customary or convenient type, and generally comprises a pair of individual insulated wires or groups of wires twisted together and surrounded by a flexible sheath. A portion of this sheath projects into the extension 3 and is adhesively sealed therein. One of the individual wires or strands, as 13, is electrically connected to the ring 7, while the other, as 14, projects lengthwise through the bore 4 where it is fastened to the screw 15 carried by the member 16. This member 16 may be either of insulating or conducting material. When it is of insulating material the screw 15 at its end constitutes the terminal contact; when it is of the conducting material the whole device may be considered as the end contact regardless of the position or of the existence of the screw 15. Exteriorly, the member 16 is tapered as shown and the mouth of the bore is preferably tapered to receive it. A rigid tube 17 which may be ofeither insulating or conducting material is inserted loosely in the bore 4 between the member 16 and the base of the bore.

In its ordinary state the member 16 is loose in the bore as shown in Fig. 1 and the diameter defined by the contacts 5 is such as to permit them to be forced lengthwise into a standard threaded lamp socket, the flexibility I of the body permitting the necessary inward movement of the lateral contact members.

As soon as the member 16 reaches the bottom at the socket it is forced into wed ing engagement with the ends of the bore t ereby holding the lateral members against inward movement; the device can be seated more strongly by a small angular turn if desired. It is permissible that this .wedging movement of the member 16 may be accomplished by longitudinal stretching of the extension 3, which i is one reason why the bore 4 is continued past the knob 1, although this depends to some extent upon the length of the tube 17 and considerable tolerance is permissible. The only purpose of the tube 17 is to keep the conductor strand 14 fairly straight and it is not imperative that the same be used, although it sometimes assists in removing the device from the socket. This removal iseffected chiefly by an outward pull on the knob 1, which may be facilitated by a slight angular turn to the left although this is not generally necessary owing to the softness of the composition. As soon as the member 16 is freed the contact members 5 can readily approach each other by the collapsing of the bore 4, this being also assisted by the flexibility of the composition. It is very diflicult to unseat the device by a lengthwise pull on the cord 12 since this serves rather to pull the member 16 into wedging relation than to remove the body from the socket. The tapered extension 3 also supports the cord and prevents any abrupt bend which might break the wires or injure the insulation.

In Fig. 4 I have shown a modified form of end contact member and connection therefor. In this embodiment the wire 14 is attached to a metal contact part 18 located at the foot of the bore 4 and havin at its forward end a threaded socket receivlng the shank 19 of the conical member 16. I have in both these cmbodiments shown the end contact member as removable for the purpose of introducing and withdrawing the core about which the body is molded.

In Figs. 5 and 6 a somewhat similar body is made of the same-soft material, formed ,with a knob 1 and a cylindrical portion 2 having contact members 5 separated by external grooves 10. The bore 4, however, opens from the rear, the forward end of the portion 2 being closed with an integral web 20 of the rubber or other like material having embedded therein a terminal contact member 16*. In this embodiment the different contact members 5 are all separate from each other, being connected only by the one strand 13 of the wire, the other strand 14 being connected to the contact 16". I have here shown the knob 1 as provided with a stiffening ring 21 for greater strength. The general effect of the web 20 is of a flaring or conical nature so as to permit ready yielding of the lateral contact members upon insertion into the socket, and also to wedge them outwardly upon longitudinal pressure of the contact 16 when the same reaches the bottom of the socket. Pull on the cord 12 also tends to hold the device the more tightly, but pull on the knob 1* tends to loosen the device. In this form the bore is also made larger for increas ing the flexibility.

In both the devices heretofore described the flexible cord is permanently molded into the fitting which exhibits certain advantages in factory production, but is not applicable to retail or replacement uses. In Fi 7 I have illustrated a modification of the device shown in Fig. 5 to fit it for retail or replacement purposes. The lmob 1, body 2*, bore 4*, contact 16 and web 20 appear as in Fig. 5. The contact members 5 instead of being separate from each other are formed as arms from the cylindrical sleeve 24 which is 10- cated in the bore 4" and internally threaded for the reception of the metal sleeve carried by the lug 26 which last is of insulating material and is formed with a passageway 27 for the reception of the wire and with suitable lugs 28 whereby it ma be screwed in and out. The inner end 0 the lug is rovided with a post 29 carrying the ongitu inally" ielding contact sleeve 30 (a sprm is here s own to permit this yielding) and t e contact member 16" terminates in a washer or other plate 31 adapted to be engaged by this sleeve. Suitable screws 32-32 are provided for the wires, which are attached to the plug 26 prior to its insertion in the body.

In Figs. 8 to 10 inclusive another type of device is shown comprisin a cylindrical hollow body 2 of the soft yieIding material and a terminal or base late 35 of some hard and rigid substance suc as orcelain or hard rubber. The forward en of the member 2 is closed as before with an inclined web 20 formed at its outer end with a projection 36 having a lon itudinal bore in which the end contact member and securing screw 16 is removably inserted. The lateral contact members 5 consist of round headed rivets secured in the flexible parallel arms 37 of the sheet metal rin 38 inserted in the mouth of the cavity 4". e base plate 35 is formed with an external lip 40 loosely receiving the body 2 and with a central aperture 41 for the flexible cord '12. Rigidly secured to the inside of this plate is a metal contact member 42 of arcuate form adapted to fit snugl within the rin 38; and this member 42 re erably subten s more than a half circ e in order to make certain contact at all times notwithstandin the flexibility of the ring 38 and the so tness of the body 2. Also carried by the member 35 is a metal bracket 43having at its inner end a threaded hole 44 for the rece tion of the screw 16 whereby the parts 0 the plug are held together. A hollow sleeve 45 is referably inserted between the end of the bracket 43 and bottom of the recess 4. The wire terminals are secured to the member 42 and bracket 43 respectively.

Fig. 11 illustrates the simplest possible form in whicha device of'this character can be made, namely. a plain cylindrical body 2 of soft material havin a terminal lateral contact 5 and a termina contact 16 consisting merely of metal contacts to which are connected the terminals of the cord 12. This body, however, must be made of exceedin l y soft material, such as spongy rubber an is not so long lived as the other devices, though it maybe made more cheaply. It is sufiicient if there be only a single lateral contact as shown in Fig. 11, although it is convenient to have other projections as shown at even though they be dummies, to render the device symmetrical in appearance and also to support it centrally in t e socket. Another sim 1e form which my invention may take is s own at Fig. 12 wherein a hollow cylindrical body 2 of soft material has a conical forward end 20 and a metal ring 51 surrounding its open end and preferably molded in place. The lateral contacts consist of brass screws 5 clamped upon one strand ,of the cord 12 while the terminal contact consists of another brass screw 16 clamped upon the other strand of the cord. A knob part 52 is detachably secured by means of screws 53 in the ring 51.

In order that there may be no misunderstanding relative to what I mean by socket I have illustrated in Fig. 13 a simple illustration of a typical form for which my improvements are designed, the-same comprising a shell 55 formed with rounded helical corrugations and located inside an insulating body 56. At its bottom the socket is closed by a base part 57 carrying a central contact member 58 insulated from the shell 55. The socket wires are fastened to suitable screws 59, 59.

When my improved plug is made separable as shown in Figs. 7 to 10 inclusive the parts 'thereof are preferably attached to the end contact rather than the side contacts in order that the lateral movement of the latter may not be impeded. Indeed by making the device in the form of a more or less stilf central core surrounded by a soft flexible sleeve on which the side contacts are carried, the insertion of the core facilitates the enterin of the side contacts by the lon itudina stretching thereof, while the with rawal of the core tends to shorten and thicken the sleeve, thereby holding it the more tightly. Similarl if the plu be turned cloc Wise when fu 1y inserted t 1e same bunching will occur, but this can be stop ed at any desired limit by adjustinglthe ardness of the composition chan ing t e size of the central cavity, or the wi th and depth of the external notches. Ihe lateral contacts may vary in length and number from a single stud located at one side to several longitudinal serrated strigs. I refer to employ three contacts equi istant y spaced about the periphery since these serve to center the plug and insure good electrical connection. It will be apparent, however, that many and great changes may be made in design and appearance and. I do not restrictmyself except as shown in the prior art.

Having thus described my invention what I claim is:

1. An electric cord terminal for threaded sockets comprising a body of soft flexible insulating material such as soft rubber having a contact member at its end adapted to engage the bottom of the socket and one or more circumferentially spaced, longitudinally projecting contact members of limited member carried by said projection adapted to engagethe bottom of the socket and one or more circumferentially spaced, longitudinally projecting contact members of limited angular extent carried by the side of said body near its end adapted to engage the side wall of the socket, the exterior of said body being longitudinally channeled between adjacent contact members.

3. An electric cord terminal for threaded sockets comprising a hollow body of soft flexible insulating material such as soft rubber having a contact member at its end adapted to engage the bottom of the socket and one or more longitudinally projecting contact members of limited angular extent in the side -wall adapted to engage the side wall of the socket, and the lateral contact members having projections adapted to be held yieldingly in the threads of the socket to which the terminal is applied.

{1. An electric cord terminal adapted to be inserted into and withdrawn from a threaded socket by a direct pull, characterized by having longitudinally extending radially yielding contact members molded in and carried by a soft flexible substance such as soft rubber, said contact members having projections adapted to be held yieldingly by said substance in the threads of the socket to which the terminal is applied.

5. An electric cord terminal adapted to be inserted into and withdrawn from a threaded socket by a direct pull, characterized by having a central substantially rigid core and a sleeve of soft flexible material as soft rubber surrounding said core, and one or more lateral contacts carried by said sleeve, said contacts having portions molded in and submerged by said flexible material and also havin projections adapted to be held yieldingly y the elasticity of said sleev'e in, contact with the threads of the socket to which the terminal is applied.

6; An electric cord terminal adapted to be inserted into and withdrawn from a threaded socket by a direct pull, characterized by having a central substantially rigid core and a sleeve of soft flexible material as soft rubber surrounding said core, the end of said core engaging said sleeve, and one or more lateral contacts carried by said sleeve, said contact members having projections adapted to be held ieldingly by said substance in the threa s of the socket to which the terminal is applied.

7. An electric cord terminal adapted to be inserted into and withdrawn from a threaded socket by a direct pull, characterized by having a central substantially rigid core and a sleeve of soft flexible material as soft rubber surrounding said core, the forward end of said core having a terminal contact and said core also engaging said sleeve, and one or more lateral contacts carried by said sleeve, said contact members having projections adapted to be held yieldingly by said substance in the threads of the socket to which the terminal is applied.

8. An electric cord terminal comprising an elongated body of soft flexible material as soft rubber, having in its exterior surface a plurality of longitudinal grooves, and ribs between said grooves, lateral contact members carried by said ribs, and an end contact member carried by said body.

9. An electric cord terminal comprising an elongated body of insulating material having spaced longitudinal portions of soft flexible material such as soft rubber, and laterally facing contact members carried by said flexible portions and adapted to yield transversely so as to be insertible into or Withdrawable from a threaded socket by a direct pull.

In testimony whereof, I hereunto afiix my signature.

HAROLD ELNO SMITH.

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