US1764418A - Insulator - Google Patents

Description

Patented June 17, 1930 UNITED STATES PATENT OFFICE HOUSE ELECTRIG & MANUFACTURING COMPANY, A CORPORATION VANIA 0F PENNSYL- INSULA'IOR Application filed April 2, 1927.

My invention relates to insulators and particularly to insulators subject to cantilever loads, such as those for supporting bus-bars, switches and the like.

One object of my invention is to provide a device of the above-indicated character that shall so convert cantilever load forces into compression forces as to provide a more effective insulator than those heretofore em ployed and one that is less subject to damage.

Another object of my invention is to provide a bus-bar or similar insulator, subject to cantilever load, that shall utilize the ad vantages of fibrous insulating material under tension and refractory insulating material under compression.

Another object of my invention is to pro vide an insulator that shall so embody a relatively-short and small-diameter fibrous strain rod and a longer refractory insulating tube of considerably greater diameter as to facilitate the conversion of cantilever load forces into compression forces, to provide a stable base for the insulator and to utilize the surface-creepage distance of the refractory tube to maximum advantage.

Another object of my invention is to provide an insulator that shall embody a tubular insulating member of relatively great diameter or base area for co-operation with a main supporting structure, and a single means for holding a conductor, converting cantilever load forces into compression forces and mounting the insulator.

' Another object of my invention is to pro vide an insulator that shall comprise parts of such relation and simple form as to great-- ly facilitate the manufacture and assembly thereof. l

A further object of my invention is to provide an insulator that shall be compact and durable in construction, economical to manufacture and effective in its operation.

' In insulators for supporting bus-bars and other conductors in such position and relation as to subject the same to cantilever loads, damage, caused by bending tendency of the insulators, frequently occurs and, in insulators embodying refractory or similar hard brittle material, this damage usually Serial N0. 180,442.

occasions break down of the insulator, With the resulting economical loss in labor and material, as well as the interruption of service.

Insulators of the character specified above have also, usually, embodied terminal members or end caps Which shorten the surfacecreepage distance thereof. Accordingly, in practicing my invention, I provide a refractory insulating member that is so Worked in compression, a fibrous insulating member that so shares the load and assists in converting the cantilever forces into compression forces in the refractory member and other features that are so combined and related to the refractory and fibrous members as to overcome the objectionable features of prior insulators and to attain the objects set forth above.

The single figure of the accompanying drawing is a side View, partially in section and partially in elevation, of an insulator constructed in accordance With my invention. 5

The device comprises, in general, an outer tubular shell or protective member 2, a strain insulator therein comprising an insulating rod or member 3 and metal end or terminal structures 4, end closure members 6 for the shell 2, cushioning and sealing means 7 between the shell 2 and the endclosure 6, nuts 9 and lock Washers 10 for holding the end-closure members 6 in position and a body 12 of insulating filler mate rial in the shell 6 about the strain insulator 3 and portions of the terminals 4 thereof.

The shell 2, preferably of refractory insulating material, such as porcelain or glass, is formed as a cylindrical tube having ends that are preferably flat or substantially normal to the longitudinal axis of the tube corrugated outer surfaces 14 and inner surfaces 15 that are sloped to render the tube slightly thicker at its mid portion than at its ends.

The rod 3, of fibrous insulating material, such as Wood, impregnated paper or cloth, molded composition or other suitable material, is preferably provided With substantially frusto-conical ends 17 and an annular co-operate With, the ends of the strain inthe corrugated intermediate portion 18 that is thicker at its central section than at the lesser bases of the frusto-conical ends 17. The lateral extreme end surfaces of the member 3 are offset from the corresponding end surfaces of the shell 2. Each of the terminal structures 4 preferably comprises a portion 20, initially of substantially straight-sided cup-shape, that is swaged in position over 'one of the frustoconical ends-17 and a screw-threaded shank portion 21 on which one of the nuts 9 is mounted. 1

Each end-closure member 6 is referably constructed of yieldable or resi lent sheet material, such as sheet steel having a suitable coating thereon, to beof substantially discoidal character having substantially parallel-plane offset inner and outer portions23 and 24 that are disposed over, and

sulator 3 and the shell 2, respectively.

This construction provides a space, between the end of the strain insulator 3 and the end of the shell 2, for the nut 9 and the lock washer 10 or other suitable holding means co-operating between the'shank 21 and the end-closure member 6, whereby space is conserved and the insulator is provided with suitable end areas for stable mounting of the insulator and stable mounting of 'a bus-bar or other structure on the insulator. V i i The end disks or plates 6 are also so biased inwardly on the insulator 3 against askets 7 and shell 2 by the nuts 9 as to p ace the shell 2'in compression and to effect a strong seal against the escape of the filler material 12.

In the above-described structure, the strain insulator or rod 3, together with its end terminal members .3, constitute a single means for holding a bus-bar or other conductor, for. assisting in converting bending forces into compression forces in the shell 2 andffor holding the entire insulator to a main stationary supporting structure (not shown) at a single position between the insulator andsthe main supporting structure. This position is along, and closely adjacent to, the base-end shank 21, in contr'adistinction to prior-art structures having a plurality of bolts distributed about the perimeter of the insulators at the, base ends thereof. e

Further, since the members 6 are of discoidal form and do not'extend' along the outer surface of the shell 2, as in prior practhe full insulating value of thesurface 14 is obtained, giving greater effective length to the insulator for the same amount of material. v r V In operation, with one end of the insulator fixed to the main supporting structure, cantilever load at the other end thereof tends to bend the strain insulator near the main support. This tendency biases the outer plate 6 against the shell 2, whereby the latter, in addition to the compression effected therein by the plates 6, as above described, issubjected to load compression. The shell 2 is, therefore,.relatively free of any forces except compression forces and is therebyoperated under its best condition.

By m'y-invention, an insulator is provided that embodies arts of simple manufacture and easy assem ly which are operated'under vadvantageous conditions and are protected against damage. The device is also adapted for the readymounting thereof and the reception thereon of the conductor which it is to support, is rugged and durable, is effective in operation, and is, in general, an improvement over similar devices heretofore employed,

'While I have shown and described a particular form of my invention, changes may be effected therein without departing from the spirit and scope thereof, as set forth in the appendedclaims.

. I claim as my invention:

1. An insulator subject to cantilever load comprising a tubular insulating shell of relatively large diameter and short length,oan insulating strain rod therein ter compared to the diameter of the shell and having ends inwardly offset from the ends of the shell, means for closing the ends of the shell and converting cantilever load forces of the rod into compression forces in the shell including end plates having periof small diamethe ends of projecting through K 2; An insulator comprising a tubular in:

sulating member, a strain insulator disposed therein with'a-n end'inwardly offset from an end of the tubular member and an end-closure member of discoidal sheet-material character having its outer perimeter co-operating with the end of the tubular member and a depressed central portion co-operating with the end of the strain insulator. i

3. An insulator comprising a tubular insulating member, a straininsulator disposed therein with an end inwardly offset froman end of the tubular member and an end-closure member of discoidal resilient sheet-materialcharacter having its outer perimeter over the end of the tubular member and its central portion flexed inwardly and fixedto the strain insulator. 4. An insulator comprising a tubular insulating member, a strain insulator disposed therein with an end inwardly oflset from an end of the tubular member, an end closure member of discoidal sheet-n'iaterial characterhaving substantially parallel-plane ofl'set portions over said ends and means in the space provided by the offset portions of the disk for securing the disk to the strain in sulator.

5. An insulator comprising a tubular insulating member, a strain insulator disposed therein with an end inwardly offset from an end of the tubular member and a terminal shank projecting outwardly beyond said tubular end, an end closure member of discoidal sheet-material character having substantially parallel-plane offset portions over said ends and means in the space provided by the offset portions of the disk cooperating between the shank and the disk for holding the disk in position.

6. An insulator comprising a tubular in sulating member, a strain insulator disposed therein with an end inwardly offset from an end of the tubular member and a terminal shank projecting outwardly beyond said tubular end, an end closure member of discoidal sheet-material character having substantially parallel-plane offset portions over said ends, a yieldable gasket between the discoidal and tubular members and locking-nut means on the shank in the space provided by said offset portions of the disk for holding the disk in position.

7. An insulator comprising a refractory insulating tube having sloping inner surfaces and walls of longitudinallywarying thickness, a fibrous strain insulator therein having its ends inwardly offset from the ends of the tube, meta terminal members having portions secured to the ends of the strain insulator and shanks projecting be yond the ends of the tube, discoidal metal members having offset substantially parallel-plane portions over the ends of the tube and strain insulator, means within the outer planes of the disk for holding the disks in position and an insulating filler medium surrounding the strain insulator in the tube.

8. An insulator comprising a refractory insulating tube having flat ends, a fibrous strain insulator therein having its ends inwardly offset from the ends of the tube, metal terminal members having cup-portions secured in position over the straininsulator ends and shanks projecting beyond the ends of the tubular member, sheet-metal disks having parallel-plane offset portions over the ends of the tube and strain insulator, means in the spaces provided by said offset disk portions eo-operating etween the disks and the shanks for holding the disks in position and a body of insulating material filling the remaining space in the tube.

9. An insulator comprising a refractory insulating tube having flat ends and corrugated outer side surfaces, a wood strain insulator disposed therein having corrugated sides and frusto-conical ends inwardly offset from the ends of the tube, metal terminal members having cup portions swaged in position over said frusto-conical ends and screw-threaded shanks projecting beyond the ends of the tubular member, sheetmetal disks having parallel-plane offset portions over the ends of the tube and strain insulator, lock washers and nuts in said shanks in the spaces provided 'by said offset disk portions, yieldable gaskets between the tubular member and the disks and a body of insulating material filling the remaining space in the tubular member.

10. An insulator subject to cantilever loads comprising a refractory insulating tube of relatively large diameter and short length having flat ends and corrugated outor side surfaces, a fibrous insulating strain rod therein of small diameter compared to the diameter of the tube and having substantially frusto-conica-l ends inwardly offset from the ends of the tube, metal terminal members having cup portions swaged in position over said frusto-conical ends and screw-threaded shanks projecting beyond the ends of the tube, means for closing the ends of the tube and converting cantilever load forces of the rod into compression forces in the tube including apertured sheet-metal disks having substantially parallelplane ofl'set portions over the ends of the tube and the rod, yieldable gaskets between the disks and the tube, locking nut means on the shanks for holding the disks and an insulating filler material in the tube.

In testimony whereof I have hereunto subscribed my name this 30th day of March, 1927.

EViUJlER H. SCHRAMM.

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