US3194878A - Insulating shield for protecting electrical junctions - Google Patents

Description

July 13, 1965 J. SCHNEIDERMAN INSULATING SHIELD FOR PROTECTING ELECTRICAL JUNCTIONS Filed April 2, 1963 INYENTOR. Joseph Sch nelderman United States Patent 3,194,878 INSULATING SHIELD FOR PROTECTING ELECTRICAL JUN CTIONS Joseph Schneiderman, 6649 N. Rockwell St., Chicago, Ill. Filed Apr. 2, 1963, Ser. No. 270,036 4 Claims. (Cl. 174-138) This invention relates to improvements'in devices for protecting live electrical junctions which are of a more or less permanent character and which are occasionally to be rendered accessible to be disconnected and recoilnected but which are, in the interim, shielded against human contact.

One example is found in the field of signs employing sealed tubing containing a gas which is subjected to a high voltage to derive the benefits of the brilliant glow discharge thus resulting. Such signs are commonly referred to as neon signals although argon, xenon and other gases or mixtures thereof are also employed for dilterent color effects.

In many installations the tubing is connected to the source of high voltage, e.g. the secondary of a transformer by the use of a readily disconnectible junction. For example, a sign of this character is often supported in a store window by terminating each of the leads issuing from the tubing in an S-hook which is engaged over a companion hook forming the end of the secondary leads of a transformer which is fixed above. Thus the sign as a whole is readily removable and replaceable by disengaging the respective pairs of hooks during cleaning of 2,482,129 and 3,007,995. The present invention discloses another form of device for the same purpose having some advantages over those previously disclosed.

Among the advantages to be possessed by such devices are (1) capability to provide good electrical insulation against high voltages, e.g. 12,000 volts, (2) non-frangibility to counteract careless handling on the part of the operator, (3) capability to retain a selected position, viz. junction-shielding or junction-exposing position, the latter being a necessary convenience to retain the'device away from the junction zone to avoid interference when the junction is separated and re-constituted, (4) adaptability to different outside diameters of conductor in order that one style of device may serve, thereby decreasing problems of manufacturing cost and inventory, (5) means for gripping the insulation of the conductor without the hazard of cutting or abrading the same, (6) capable of being 'fabricated'in simple, and therefore inexpensive molds, and (7) case of installation on the conductor.- The present invention has for its objects compliance with these and other desiderata.

Other objects and advantages of the invention will become apparent from the ensuing description which, taken with the accompanying drawings, discloses certain forms in which the principles of the invention may be embodied.

In these drawings:

FIG. 1 is a combined side elevation and longitudinal cross section of one embodiment shown in its relation to a pair of readily disconnectible conductors;

FIG. 2 is an enlarged top plan view thereof;

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FIG. 3 is a partial, enlarged view adapted from FIG. 1, but with the device disassociated from the conductors;

FIG. 4 is an enlarged transverse cross section taken on the line 4-4 of FIG. 3;

FIG. 5 is a view similar to FIG. 4 with the device mounted on the upper conductor;

FIG. 6 is a view similar to FIG. 1, showing a modified embodiment;

FIG. 7 is an enlarged top plan View thereof;

FIG. 8 is a view similar to FIG. 3 of this modified form;

FIG. 9 is a transverse cross section taken on the line 9-9 of FIG. 8.

Broadly regarded, the invention resides in a sleeve of molded plastic composition capable of providing adequate dielectric strength to protect against the potential of the junction. Such junction may be of any type which is to be disconnected and re-connected at intervals as for example, in the case of neon signs of the type mentioned above. The conductor with which the device is engaged has an appropriate diameter of insulation of rubber or plastic composition which may vary from one conductor to another, depending upon the installation. The device is of hollow cylindrical form over its major extent and,

at one end, has an opening to admit the largest size of conductor within a range of sizes to which a particular design of device is adapted in order to render the same versatile in use. At the other end the device is open to admit the other conductor and this opening may be oversized or not with respect to said other conductor as long as such open end will clear the maximum transverse dimension of the junction proper. The length of the device will be such as to. provide adequate shielding of the bare leads and their terminations, if any. At the said one end the device is provided with a plurality of inwardly-directed fins or equivalent members of such configuration, including thickness, as will allow the same to flex as the conductor is introduced therebetween and, by their resiliency, grip the same. By molding the device of polypropylene, polyethylene or similar resilient plastic compositions, the device is not only proof against fracture but the fins may be molded integrally. The fins are so shaped on their conductor-engaging faces as to provide easy initial assembly of the device with the conductor and to avoid damage by cutting or abrasion. Regarded asa group these fins define a curved throat for entrance in either direction. The hollow cylindrical main body has a wall thickness so calculated as to result in not only a reasonably rigid device, i.e. one'that may be described as shape-retaining in a broad sense, but which may yield slightly in the region of the fins. Thus, if desired, the fins may be regarded as yielding laterally and/ or radially to accommodate the conductor and, if further accommodation is required the wall also may yield slightly. Alternatively, the ribs may be relatively non-compliant and the necessary resilient grip obtained principally by outward bulging of the wall. By reason of the resiliency of the parts as just described the device may be shifted along the conductor and there maintain itself in its two principal positions, viz. junction-shielding and junction exposing positions. I

In an alternate aspect the gripping of the device on the conductor may be through the medium of a plurality of cantilever fingers at the said one end, the free or distal end region of the fingers cotacting the conductor. Since resilient material is contemplated for the device, and the sameis preferably of one-piece construction the fingers will yield appropriately and present friction on the conductor to maintain the device in its two principal positions. The fingers are so conformed as to present an entrance throat at each end thereof for the purpose explained in connection with the principal embodiment.

Where, herein I employ the term conductor it is in the general sense of a conductive core surrounded by insulation. Where the core per se, is referred to, the context will so indicate.

Reverting to the drawing I have shown, by Way of example, a one-piece device, having a body in the form of a hollow cylinder it? over most of its length and having an aperture 12 at the upper end to admit freely the largest diameter of conductor to which the device is adapted, e.g. of diameters say between A" and The body and the fins shortly to be mentioned are preferably molded in one piece of some suitably resilient, yet generally shape-retaining plastic composition, e.g. polypropylene or polyethylene. It is preferred that the material not support combustion such as might be initiated by arcing at the junction.

The pair of conductors 18 and 19 comprise respective leads 21 and Z2 and the surrounding insulation. The confronting ends 23 of the leads are each twisted around individual S-hooks 24 which may be rapidly engaged and disengaged. This construction would be typical of the junctions between the secondary of a transformer and a neon sign suspended therefrom. However, the junction may take other well-known forms. It will therefore be understood that the internal diameter of the body 10 will be chosen to clear a junction of the expected largest diameter in order that the device may be shifted axially Without interfering therewith.

Adjacent one end of the device; in the example, the upper end, there is provided a plurality of fins 31, in this case, three, extending radially inwardly and positioned desirably equ-iangularly. These fins are arcuate along the edge 32 and, in the absence of the conductor, have these edges positioned on a ,common circle of less diameter than the diameter of the smallest conductor to be received. Thus, when the fins are engaged with the conductor they are urged outwardly and/ or deformed laterally to exert a constant vise-like action on the conductor which will be sufiicient to maintain the device against accidental dislodging forces axially applied, but such action is not to be so intense as to preclude easy, manual shifting of the device between its two operative positions. Although reference has been made to the edges 32 being positioned on a common circle this is not intended to mean that such edges conform to the curvature of the circle since they may be flat or of other form. The cross section of FIG. 5 shows the fins in a deformed arrangement, but exaggerated for clarity of exposition. In fact, and as mentioned heretofore, the ribs may be relatively rigid in a radial sense and the wall of the body it? permitted to distend to apply the appropriate gripping force on the conductor. PEG. 4 is similar to FIG. 5 but with the conductor absent.

It will be noted that the curvature, in side elevation, of the fins 31 (FIG. 3) is selected to define a throat at each end thereof to facilitate introduction of the conductor from either direction. This curvature need not be continuous since an axially straight conductor-contacting portion may be flanked by upper and lower arcuate portions. There may be an arcuate mid-portion flanked by upper and lower straight portions. Alternatively, the linear conformation of the edges 32 may provide an entrance throat at only one end. Moreover, the edges 32 may comprise a plurality of rectilinear portions throughout which, together, may be regarded as substantially arcuate.

From the foregoing it will have become evident that the invention device provides reliable shielding of the disconnectible junction when the same is live, and that the same may be shifted along the upper conductor to expose the junction for disconnection when the same is dead. Meanwhile the device remains out of the way, being held against gravity by the frictonal grip thereof on the conductor.

Qperation of the alternative embodiment of FIGS. 6

to 9 will be clear from the foregoing. In this form frictional engagement is through a plurality of cantilevered fingers 61 extending inwardly from one end of are body 62, or some intermediate portion thereof. These fingers are desirably of thicker cross section at the base, or upper end, and gradually diminish to a distal end of lesser cross section pursuant to the principles applied in the construction of cantilevered beams generally. That is to say, the base portion is rendered strong enough to preclude fracture and the distal portion is proportioned to apply adequate, but not excessive, pressure to the conductor. The curvature or other configuration of the inward surfaces 65 of the several fingers is subject to variation in the same manner as has been described in connection with the edges 32 of the fins 31; similarly with regard to the throat or throats facilitating threading of the conductor.

While I have shown particular embodiments of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

I claim:

1. A device for slidable movement between two positions respectively shielding the junction of a pair of aligned electrical conductors, one of said conductors being of a given diameter and alternatively exposing the junction comprising: a hollow cylindrical body of electrically-insulating material open at both ends, at least one end of the body having an annular edge, the interior wall surface of said body for a portion of its length inwardly from said edge carrying a plurality of radially-inwardly-extending, axially-extending, mutually coextensive, independent, flexible members of resilient but generally shape-retaining character, the inner edge of said flexible members defining a smooth continuous convex curve, said flexible members defining a passage way having a minimum diameter smaller than said given diameter at a point intermediate the length of said flexible members and a diameter greater than said given diameter adjacent the ends of said flexible members, said flexible members being adapted to grip said one of the conductors with a force precluding unintended sliding of the device along the said one conductor but capable of being overcome manually to slide the same between its two positions, the remainder of said interior wall surface from said members to the other end of said body surrounding the junction when the device is in junction-shielding position.

2. The device in accordance with claim 1 wherein said members are of fin-l-ike form having such dimensions measured transversely of the principal axis of the body in relation to the material thereof as to flex principally in a radial direction into said gripping relation.

3. A device for slidable movement between two positions respectively shielding the junction of a pair of aligned electrical conductors, one of said conductors being of a given diameter and alternatively exposing the junction comprising: a hollow cylindrical body of electrically-insulating material open at both ends, at least one end of the body having an annular edge, the interior wall surface of said body for a portion of its length inwardly from said edge having a plurality of radially-inwardly-extending, axially-extending mutually coextensive, independent, flexible fingers of resilient but generally shape-retaining character cantilever-carried on said interior wall surface, said fingers extending principally axially of the body, the inner edge of said flexible fingers defining a smooth continuous convex curve, said fingers defining a passageway having a minimum diameter smaller than said given diameter at a point intermediate the length of said fingers and a diameter greater than said given diameter adjacent the ends of said fingers, the distal end of each of said fingers being adapted to flex radially to grip said one of the conductors with a force precluding unintended sliding of the device along the said one conductor but capable of being overcome manually to slide the same between its two positions, said fingers occupying only a portion of the length of said interior Wall surface, the remainder of said surface beyond the fingers surrounding the junction when the device is in junction-shielding position.

4. The device in accordance with claim 3 in which the fingers are each of larger cross section adjacent the basal end than at the distal end.

References Cited by the Examiner UNITED STATES PATENTS 6 7/60 Homing n l74-138 X 8/60 Rapata 174-453 X 11/61 Schneiderman 174-5 4/62 rebs 174-93 X 12/63 Schneiderman 174-5 X FOREIGN PATENTS 5/58 Canada. 1/53 France.

JOHN F. BURNS, Primary Examiner.

JOHN P. WILDMA-N, E. JAMES SAX, Examiners.

Claims (1)

1. A DEVICE FOR SLIDABLE MOVEMENT BETWEEN TWO POSITIONS RESPECTIVELY SHIELDING THE JUNCTION OF A PAIR OF ALIGNED ELECTRICAL CONDUCTORS, ONE OF SAID CONDUCTORS BEING OF A GIVEN DIAMETER AND ALTERNATIVELY EXPOSING THE JUNCTION COMPRISING: A HOLLOW CYLINDRICAL BODY OF ELECTRICALLY-INSULATING MATERIAL OPEN AT BOTH ENDS, AT LEAST ONE END OF THE BODY HAVING AN ANNULAR EDGE, THE INTERIOR WALL SURFACE OF SAID BODY FOR A PORTION OF ITS LENGTH INWARDLY FROM SAID EDGE CARRYING A PLURALITY OF RADIALLY-INWARDLY-EXTENDING, AXIALLY-EXTENDING, MUTUALLY COEXTENSIVE, INDEPENDENT, FLEXIBLE MEMBERS OF RESILIENT BUT GENERALLY SHAPE-RETAINING CHARACTER, THE INNER EDGE OF SAID FLEXIBLE MEMBERS DEFINING A SMOOTH CONTINUOUS CONVEX CURVE, SAID FLEXIBLE MEMBERS DEFINING A PASSAGE WAY HAVING A MINIMUM DIAMETER SMALLER THAN SAID GIVEN DIAMETER AT A POINT INTERMEDIATE THE LENGTH OF SAID FLEXIBLE MEMBERS AND A DIAMETER GREATER THAN SAID GIVEN DIAMETER ADJACENT THE ENDS OF SAID FLEXIBLE MEMBERS, SAID FLEXIBLE MEMBERS BEING ADAPTED TO GRIP SAID ONE OF THE CONDUCTORS WITH A FORCE PRECLUDING UNINTENDED SLIDING OF THE DEVICE ALONG THE SAID ONE CONDUCTOR BUT CAPABLE OF BEING OVERCOME MANUALLY TO SLIDE THE SAME BETWEEN ITS TWO POSITIONS, THE REMAINDER OF SAID INTERIOR WALL SURFACE FROM SAID MEMBERS TO THE OTHER END OF SAID BODY SURROUNDING THE JUNCTION WHEN THE DEVICE IS IN JUNCTION-SHIELDING POSITION.

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