US1902568A - Fused electrical plug - Google Patents

Description

, March 21, 1933. L. MAXAM FUSED ELECTRICAL PLUG Filed April 10 FIE- Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE LEONARD L. mm, 01 LOS ANGELES, CALIFORNIA, ASSIGNOR OF ONE-THIRD TO CLARENCE S. CREWS, OF SAN PEDRO, CALXII'ORNIA FUSEID ELECTRICAL PLUG 7 Application filed April 10, 1931. Serial No. 529,115.

This invention relates to electrical equipment, and has for an object the provision of an improved type ofelectrieal plug for use in. releasably connecting a flexible conductor to the terminals of an electrical socket which also may be carried by a flexible conductor, or which may be disposed within a rigid structure such as a floor, or wall. 1

A more detailed object is the provision of 10 an electrical plug of the general character de-' scribed, which is capable of making or breaking a plurality of electrical circuits simultaneouslv.

A further object is the provision of an elec- 16 trical plug which is adapted to maintain a predetermined polarity of the opposite conductorsof a circuit, i. e., a plug in which means are provided for preventing the insertion of the plug within its socket, in any 20 manner other than that which will result in a predetermined polarity vof the conductors to which the plug is secured.

A further object is the provision of an electrical plug as described, in which fuses are interposed between the conductors and the contacts of the plug, these fuses being car ried within the body of the plug itself.

A still further object is the provision of a plug, wherein means are provided for attaching the conductors to the plug, in such a manner that a considerable force may be imposed upon the plug to remove it from its socket, this force being in the nature of tension upon the conductor, and still avoid any possibility of severing the connection of the conductors to the plug.

A still further object is the provision of an electrical plug as described, in which means are provided for resiliently pressing the contacts of the plug against those of the socket when the plug is positioned operatively therein.

A further object is to provide means for locking the plug within its socket, preventing accidental removal of the plug, and requiring the exertion of conscious effort on the part of the operator, to remove the plug.

The invention possesses other objects and advantageous features, some of which, with those enumerated, will be set forth in the following description of the inventicns particular embodiment which is illustrated in the drawing accompanying and forming a part of the specification. I

Referring to the drawing Fig. 1 is a perspective View of a plug incorporating the principles of the present invention, and showing the cover with which the plug is provided, moved to open position so as to better disclose the nature of the invention.

Fig. 2 is a vertical transverse sectional View. The plane of section is indicated by the line 22 of Fig. 1, and the direction of view by the arrows.

Fig. 3 is a perspective view of the plug pushed partially into its cooperative socket, to better disclose the manner of the plugs employment. Portions of the figure are broken away to reduce its size.

Fig. 4 is a horizontal sectional View taken upon the line 44 of Fig. 3, with the direction of view as indicated.

The plug of the present invention has been designed with the especial object in View of 7 providing convenient means for establishing the circuits whereby the reproducing unit of a dynamic loud speaker is energized, and more especially for use in conjunction with that type of sound reproducing instrument which is employed to reproduce sounds accompanying action depicted cinematographically. However, it should be understood that the plug is adaptable to practically universal usage, and may be employed wherever 85 it is desired to provide means for quickly establishing and breaking one or more electrical circuits.

It should be pointed out by way of explanation of the use to which the plug of the pres 90 cut invention is put, that loudspeakers of the general class indicated hereinabove require two circuits, to-wit: the field circuit or the circuit associated with the field coil of the reproducing unit, and the talking circuit or 95 the circuit whereby the moving coil of the speaker is energized. In stage installation, it has been customary to interpose fuses within the field circuit, inasmuch as this circuit ordinarily carries a considerably greater quantity p 'of current than the talking circuit. 'I Iowever,

in all installations of which I am at present aware, it has been customary to provide these fuses in a separate wall box, or other convenient location; and inasmuch as the socket within which the plug is to be positioned in order to ener ize the loud speaker of a tall;-

' ing moving picture installation, is ordinarily placed in the fioor of the stage, Closely behind the pro ection screen, the fuse-box and the socket are ordinarily some distance apart,

I resulting in considerable inconveniencewhenever the necessity arises for replacing a fuse.

Another feature in connection with the field and talking clrcuits of a dynamic loud speak- I posed of any suitable dielectric material such as fiber or its equivalent. A projection 7, preferably of reduced width, extends from the lower end of the body 6, and is provided with preferably a pair of spaced slots 8 both slots being in the same side of the projection 7 As is clearly indicated upon Fig. 2, the bottom 90f each of the slots 8, instead of being parallel to the sides of the plug, inclines from the bottomell ofthe plug, upward and toward that side thereof in which the slots 8 are dis posed. A contact 12 of suitable conductive material, is secured to the bottom 9 of each of tie slots 8, in any suitable manner, such as by countersunk screws 13 threaded into the material of which the body 6 is composed.

A recess 14 is formed in the body 6, in registry with the upper end of each of the slots 8, preferably the bottom of each recess 14 being 'ofiset from the bottom 9 of the associated slot 8, as clearly s iown upon Fig. 2 The up-. per end of each of the contacts 12 is sigmoidal in configuration, so as to dispose the extreme upper end 16 against the bottom of the asso ciated recess 14. Wings 18 are formed upon the extreme upper end 16 of each contact, these wings 18 being curved laterally in respect to the entire plug assembly, to resiliently grasp one of the contact ends 19 of a conventional cartridge fuse 21; with the result that the extreme upper end 16 of each contact 12 provides a spring clip for resiliently retaining and establishing electrical connection with one'termin al ot tile fuse 21. A similar spring clip 22 is provided in the opposite end of each of the recesses 14, to ac commodate the other terminal 23 of the associated fuse 21. Conductors 24 are releasably Accordingly, one ofthe fea- I connected to the spring clips 22, by means of terminal screws 26 threaded into the clips 22, and extend through the top of the body 6, recesses 27 extending from the upper ends of the recesses 14 to the top of the plug being provided for the accommodation of these conductors 24.

A second pair of contacts 31 are provlded upon the side. edges of. the extension 7 of the body 6, each contact 3 1'b'eing rigidly attached thereto'as by screws 32'or their equivalent. Each contact 31 is provided with a tongue 33 severed therefrom along all but one of its edges, and -defiected outwards slightly, as clearlyshown upon Fig. 1. Each contact 31 is also; provided with a terminal screw 34 threaded into the associated contact 31, or into thematerial of the plugitselfior both. By means of these terminal screws 34, conductors 36 may be releasably attached to the contacts 31, these conductors 36 extending from theshoulders 37 defining the upper end of the projection 7, to the top of the plug,

through recesses 38 spaced from the recesses 27. Preferably, all four of the conductors 24 and 36 are gathered intoa single bralded conductor 39, in which the several conductors 24 and 36 are insulated from each other. A clamp 41 is rigidly attached to the conductor 39,- closely adjacent that point at which the several conductors24 and 36 diverge, the

clamp 41 being firmly secured to the conductor 39, through the expedient'of its being split at one side thereof, and having screws 42 extending through opposed flanges 43; with the result that by tightening the screws 42, the flanges 43 may be pressed together to secure the clamp 41 firmly to the conductor 39. The bottom of the clamp 41 is extended laterally,

so that flanges 44 rigid therewith may em- 3 brace three sidesof the top of the plug, screws 46 extendingthrough the flanges 44, so as to rigidly and removably attach the clamp 41 to the top of theplug- A collar 47, which is connected to the plate48 of the clamp 41 by a chain 49, is clamped upon the multiple conductor 39 in such position that'any tension imposed upon the conductor 39 will be taken by the chain 49, rather than by that portion otthe conductor 39 at the point whereit extends out of the clamp '41. This arrangement permits removal of theassembled plug from its associated socket,'by exerting tension upon theconductor 39, and avoids the liability of severing the connection of one or more ofthe conductors 2401' 36, withits associated terminal screw 26 or 34, respectively, and also protects the conductor 39 bypreventing the portionthereof which receives the greatest amount of fiexure, from being subjected to tension. I I V A closure 51 is hingedly'attached to the body portion 6 bya hinge 52, permitting the closure 51 optionally to be swung to open position, as shown upon'Fig; 1, or to closed position, as shown upon Fig. 3, wherein the closure overlies the recesses 14, 27 and 38, to effectually conceal the conductors 24 and 36, and the fuses 21 with their spring clips 22 and 18. The closure 51 is releasably held in closed position, through the expedient of hinge knuckles 53 and 54 carried by the body 6 and closure 51, respectively, and which move into alinement when the closure is moved to closed position to receive a removable pin 56. The closure 51 is also provided with suitable recesses 57 and 58 adapted to register with the recesses 27 and 38, respectively, when the clo sure is closed, to better accommodate the conductors 24 and 36, respectively.

The plug hereinabove described, is designed primarily for operation in connection with the conventionalsocket or pocket as it is termed in the trade, ordinarily employed for theatrical use. Such a socket is indicated in its entirety by the character 61, and is shown as being set flush with the floor 62 of a stage, or with the outer surface of a wall. It is conventionally provided with spaced spring contacts 63 with which conductors 64- are in communication, these contacts 63 being spaced along one side of the socket 61, in registration with the recesses 8 of the plug 6. The socket 61 is also provided with contacts 66 at the ends of the socket, and with which conductors 67 are in communication. lVhen the plug 6 is thrust into the socket 61, the upper ends of the contacts 63 come into engagement with the contacts 12,

' which, on account of their obliquity, deform the contacts 63 as movement of the plug '6 into the socket 61 continues. As a result, the contacts 63 are resiliently pressed against the contacts 12, to insure good electrical contact, which is also enhanced by the wiping engagement of the contacts 12 with the contacts 63, as inward movement of the plug 6 takes place.

Simultaneously with the engagement of the contacts 12 and 63, the contacts 31 engage the contacts 66. Efiiciency of this electrical connection is insured by the spring tongues 33 which resiliently press outward against the contacts 66 when the plug is in operative position, as will be readily understood.

Means are provided for retaining the plug 6 within its socket 61 against accidental removal. A detent in the form of a plate 71 is slidably mounted adjacent the lower end of the plug, and is urged by a spring 72 to extend its end into a keeper 73 provided adjacent the bottom of the socket 61. Hence, the plug cannot be removed unless the plate 71 is withdrawn against the action of the spring 72 F or this purpose a rod 74 is provided, extending from the top of the plug 6 to the plate 71, within which a hole 76 is formed to receive a wedge 77 carried by the rod 74. A spring 78 under compression between the top of the plug 6 and a head 79 on the rod 74, normally holds the wedge 77 retracted from the hole 76, so that the spring 72 can 'push the plate 71 into the keeper 73, but by depressing the head 79, the wedge may be pushed into the hole 76, engaging the plate 71, so as to pull it away from the keeper 73,

whereupon the plug 6 may be pulled out of companying cinematographic depiction of action. Such sound reproducers require two independent circuits termed the field 0011 011- cult and the talking circuit. The conductors 24 of my plug are intended to carry the'field coil circuit, inasmuch as this circuit requires a heavier current than the talking circuit. The amount of current flowing through the talking circuit is so slight that no need is. presented for providing fuses therein; consequently, the unfused conductors 36 are intended to convey the current of the talk-ing circuit. The socket 61 is ordinarilyemployed for each of the sound reproducing devices of a bank or tower of the conventional installation. Ordinarily, there are four loud speakers distributed about the back of the moving picture screen, and consequentlv there will be four sockets 61 in the floor 62 of the stage, at a convenient location to permit insertion of a plug 6 within each socket 61, it being understood that the conductor- 39 of each plug 6 leads to one of the electrical reproducing units of the bank of speakers. Obviously. the inclusion of the fuse 21 within the plug, dispenses with the necessity of employing a separate fuse-box.

It is to be understood that the details of the invention as herein disclosed, are subject to alteration within the spirit or scope of the appended claims.

I claim:

1. An electrical plug comprising a body of insulative material, a plurality of electrical contacts lying entirely within individual recesses in a common lateral side of the body, and a conductor connected to each contact.

2. An electrical plug cooperative with a socket having a plurality of differentiated pairs of electrical contacts therein, said plug comprising a body of insulative material receivable within said socket, a plurality of pairs of electrical contacts carried by said plug and differentiated similarly to those of the socket, and means for bringing contacts of the plug into engagement with the associated contacts of the socket when the plug is inserted therein.

3. An electrical plug comprising a body of insulative material, a plurality of electrical contacts set within recesses in a common side of the body, and arconductor connected to each of said contacts, said contacts 'being'incli'ned from the bottom of said plug toward the said side thereof. i 4:. An electrical plug cooperative with a socket having a plurality of structurally differentiated pairs of electrical contacts therein, said plug comprising a body'of insulative material receivable within said socket, a plurality of pairs of electrical contacts car- .riedby said plug and difi'erentiated similar- 1y to those of the socket, means for bringing contacts of the plug into engagement with the associated contacts of the socket when the f 15 plug is inserted therein, an electrical conductor connected to each of said plug contacts, means associated with each of said plug contacts for resiliently pressing them against the associated socket contacts, and fuses in- -2 terposed between certain of said conductors and their associated contacts.

5. In combination, an electrical plug connector, a socket member therefor, and releasable means for locking said plug within said 2 socket member, said locking means comprising a detent carried by said plug, means pressing said detent'into extended position wherein said detent engages said socket memher, and means operative to withdraw said zsu detent. r

i 6. An electrical connector comprising a I plug member, a socket member adapted to re ceive said socket member, contacts carried by saidmembers and adapted to electricalco 1y engage each other when said plug memher is disposed within said socket member, a movable detent carried by one of said members and adapted to engage the other member to retain theplug member within the socket so member, and means forwithdrawing said detent. V y

In testimony whereof I have signed my name to this specification.

LEONARD L. MAXAM,

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