US1819748A - Insulator - Google Patents

Description

Aug. 18, 1931.

K. A. HAWLEY ET'AL INSULATOR Filed Feb. 4, 1924 Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE KENT A. HAWLEY AND DAVID H. OSBORNE, F VICTOR, NEW YORK, ASSIGNORS J30 LOCKE INSULATOR CORPORATION, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND INSULATOR Application filed February 4, 1924. Serial No. 690,446.

The invention relates to insulators and more particularly to high tension insulators of the suspension type. o

The principal object of the invention, generally considered, is to provide asuspenslon insulator comprising a dielectric or insulating portion and metallic members connected on opposite sides of the dielectric, said parts being so arranged as to give a high mechani- 0 cal and electrical strength.

Another object of the invention is to provide a simple, strong, reliable and ellicient type of suspension insulator particularly adapted for use under modern serviceconditions. A still further object is to provide a suspension insulator of the cap and, pin.

t pe in which the parts are so arranged that the stresses transmitted to the dielectric when. the parts are in service are substantially stresses of compression rather than tension. A still further object is to provide in a suspension insulator of the cap and pin type, means permitting a slight relative movement between either of the metalhc elements and the dielectric without injury to the bond or strength of the insulator.

To these and other ends the invention comprises the various elements and combinations of elements herein set forth, the novel features thereof being pointed out in the claims.

In the drawing the figure is a view partially in side elevation and partially in vertical section of a suspension insulator made in accordance with the invention. 7

Before describing the device in detail it will lead to a better understanding thereof to briefly point out that there has been of recent years a continual increase in the voltwhich has necessitated an increase in area of the conductor. Insulators when subject the skirt age and power carried bytransmission lines I due to the weight ed to excessive mechanical stresses have their insulating value materially reduced unless this mechanical stress is well within the ultimate mechanical strength of the insulator. The problem has therefore been to devise a suspension insulator having both increased electrical and mechanical strength. The present invention is .the result of research to solve the problem as set forth.

In carrying out the invention there is provided an insulator portion 1 comprising a downwardly flaring skirt 2 having symmetrically arranged therewith an upwardly extending neck or stem 3.0f substantially frusto conical form which is provided with a downwardly opening recess 4 withinwhich is connected, as will hereinafter be described, the headed pin or bolt 5. The under face of portion 2 may if desired be provided with a plurality of downwardly extending skirts or petticoats 6 and 7 to increase the leakage distance between the bolt 5 and theadjacent edge of the insulator cap 8 which is seated upon and connected to the neck or stem 3.

While the cap 8 and thebolt 5 are shown as of the clevis type it will be understood of course that this is merely illustrative, and

other forms of connection between the capand pin of one insulator and an adjoining insulator conductor or support, as the case mziy be, may,- if desired, be employed.

n order to connect the cap 8 to the insulator 1, the cap is provided with a hollow recess substantially conforming, except as hereinafter noted, to the stem 3, and the intervening space between'the cap and stem is filled with a cementitious compound 9 preferably formed of neat Portland cement.

To form a more perfect bond between the stem and the cement the surface of the former, from a point just above the juncture of the I stein and skirt, is provided with a roughened or corrugated portion or band 10 which may advantageously be formed by applying to the glaze, while the s'ame is wet, particles of unfired porcelain and then firing the insulator, whereupon the glaze rigidly connects the, particles or porcelain to the surface.

4: may be provided with a roughened or flaring conoidal surface 12 terminating a short distance above the open end of the cap and intersecting at this point with an inwardly flaring conical or conoidal surface 13. Corresponding elements of the intersecting conoidal surfaces are arranged at acute angles with the axis of symmetry of the insulator and subtend an obtuse angle between themselves, as clearly shown in the cross sectional View of the figure, and before the parts are assembled the angular surfaces 12 and 13of the cap are coated with an elastic compound 14.

The pin 5 is provided at its upper end with a head 15 having circumferentially arranged portions 16 and 17, the common elements of each two adjacent surfaces being arranged to form acute angles with respect to the axis of symmetry of the device and disposed at an obtuse angle to each other. Before the assembly of the pin within the recess 4 the entire surface of the head 15 is coated with the elastic compound as shown at 18.

After the cap and pin are coated the parts are assembled in the usual manner, that is, by introducing the cementitious compound 9 into the recess within the cap 8, then inverting the insulator and inserting the stem {3 within the recess of the cap and then reinverting the insulator to its normal position and permitting the parts to remain-in this position until the cementitious coinpound has set. The same operation is performed with reference to the pin 5, that is, the recess 4 within the insulator partially filled with the cementitious compound and the bolt or pin 5 is then inserted and the parts supported in assembled position until the cementitious compound 9 has set.

It will be observed that the cement 9 within the recess 4 preferably terminates at a point adjacent the lower edge of the head 15 of the pin 5 and that the throat 19 of the insulator is open from a point above the lower edge of the cap 8, and that the throat portion 19 is provided with a flaring openin 20 which merges into the lower face of the skirt portion 2. This construction improves the thermal efficiency of the insulator by permitting the ready transfer of heat from the outer to the inner surface thereof.

The elastic compound interposed between the angular portions of the cap and the cement bond and the elastic compound interposed between the angular portions of the pin and the cement bond, serve to permit a slight relative moven'lent between the cap and insulator and be en the pin and insulator when the parts are subjected to strain. Not only does the elastic coating permit a slight relative movement between the parts of the insulator, as above set forth, but it also compensates for slight irregularities in either the cap or the pin and therefore produces an equalization of pressure from said cap or pin to the insulator. By this arrangement and by employing obtuse angles as hereinbefore described, tension forces applied to the cap and pin react against the cement and are transmitted to the interposed portion of the insulator in substantially straight lines parallel to each other and acting in opposite directions. It will therefore be apparent that these tension forces are substantially converted into compression forces, the pin being held in place like the keystone in an arch and exerting diagonally outward and downward thrusts, which place the porcelain in compression between the conical or conoidal surfaces 16 on the pin and the corresponding supporting surface 13 on the cap. Since porcelain has a value under compression where the'parts are confined, as in the insulator here shown, substantially equal to the compression value of steel, it will be obvious that by utilizing .the invention the mechanical stresses imposed upon the insulator, even b extraordinary conditions of service, will e far below the ultimate mechanical strength; and since the mechanical strength or mechanical stress has a direct relation to electrical strength, it will be apparent that by utilizing the invention hereinbefore described the mechanical and electrical strength of the insulator will be materially increased.

o claim j 1. In an insulator, a dielectric body having a skirt portion and an upstanding stem, that portion of the stem adjacent the skirt portion being cylindrical and the remaining portion being gradually reduced in diameter and curved at its end to be of dome shape, said cylindrical portion being roughened, the stem having a recess therein having the innermost portion of its wall roughened,'a cap upon the stem and cemented thereto, and a pin cemented within the recess, the cap having its lower portion flared outwardly and having its edge inclined downwardly and toward the axis of the body, and the pin having a pluralit of stepped. ortions with surfaces inc ined downwar ly and toward the axis of the body to accord with the inclined portion of the cap, said inclined edge portion of the cap being located in a plane below the stepped portion of the pin, the roughened portions of the stem and recess wall being staggered and both lying in the field of compressive strain between the pin and cap.

2. In an insulator of the type in which there is provided an elastic coating interposed between the adjacent surface of a cap and they cement and between the surface of the pin and the cement, the" combination of a dielectric body having a skirtportion and an upstanding stem, that portion of the stem adjacent the skirt portion being cylindrical and the remaining portion being reduced in diameter and curved at its end to be of dome shape, said cylindrical portion being roughened, the stem-having a recess therein having the innermost portion of its wall roughened, a cap upon the stem and cemented thereto and a pin cemented within the recess, the cap having its lower portion flared outwardly and having its edge inclined downwardly and toward the axis of the dielectric body, the pin having atleast one portion of the surface inclined downwardly and toward the axis of the body to accord with the inclined portion of the cap, said inclined edge. portion of the cap being located in a plane below .of the pin, the roughened portions of the stemand recess wall being staggered and both lying in the field of compressive strain between the pin and ca In testimony whereof we afiix our signatures.

KENT A. HAWLEY. DAVID H. OSBORNE.

the inclined portion

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