US2441309A

US2441309A - Strain insulator assembly

Info

Publication number: US2441309A
Application number: US585917A
Authority: US
Inventors: Cook John Brown
Original assignee: Reliable Electric Co
Current assignee: Reliable Electric Co
Priority date: 1945-03-31
Filing date: 1945-03-31
Publication date: 1948-05-11
Anticipated expiration: 1965-05-11

Description

May 11, 1948. J. B. cooK STRAIN INSULATOR ASSEMBLY Flled March 31, 1945 Q m NE Q Q kfofirz firown Cog/7c J; 4 3 m: JZ g Patented May 11, 1948 STRAIN INSULATOR ASSEMBLY.

John Brown Cook, Chicago, Ill., assignor to Reliable Electric Company, Chicago, 111., a corporation of Illinois Application March 313545, Serial No. 585,917

My invention relates to strain insulators and particularly to an insulating member for use in a splice having characteristics similar to that shown in the patent to Fotsch 2,138,913, patented December 6, 1938.

The purpose of my invention is to provide an insulating member for the strain insulator, that is made of molded insulating'material that is reinforced with insulating fibres so as to increase the strength thereof against shear and tensile stress. i

It is the further purpose of my invention to provide insulating member made of a molded plastic reinforced with fibrous insulating members that is molded so as to form a plurality of annular grooves therein which receive the corrugations provided in sleeve-like members that serve as a means for connecting the ends of the conductors to the strain insulator.

It is the further purpose of my invention to provide an insulating member of the above referred to character in which the insulating fibre reinforcing members are causedto flow with the material in molding the annular grooves therein so that said reinforcing members are offset at The body portion of the insulating member is made up of a plastic material that is readily molded and can be made of a substantially transparent plastic material. The reinforcing fibres are preferably glass fibres and these are preferably molded in the insulating plastic body in the form of cords made up of such fibres running generally longitudinally of said insulating member. The cords can be arranged in substantial parallelism extending lengthwise of the insulating member in spaced relation, or the cords can be stranded into a loose rope, which rope is imbedded in the insulating body. In either case the cords extend substantially longitudinally of the insulating member and are molded in the plastic insulating material in such a manner as to be surrounded thereby so that the separate cords have said insulating material surrounding the same,

7 Claims. (01. 174 17s) whether the cords are separate from each other or are made into the form of a looserope-like member.

Other objects and advantages of my invention will appear as the description of the drawings proceeds. I desire to have it understood, however, that I do not intend to limit myself to the particular details shown or described, except as defined in the claims.

In the drawings:

Fig. 1 is a view partly in longitudinal section and partly in elevation through my improved strain insulator.

Fig. 2 is a section thereof taken on the line 2-2 of Fig. 1; and

Fig. 3 is a perspective view of a modified form of reinforcement used in my insulating body.

Referring in detail to the drawings, my improved strain insulator comprises the sleeve-like members 5 which have gripping jaws 6 and l therein, cooperating to secure the cdnductors 8 and 9 within said sleeve-like members against longitudinal movement relative thereto, said jaws being held in gripping engagement with said conductors by means of a coil compression spring 10, in a similar manner to that shown in the above referred to patent to Fotsch 2,138,913.

Said sleeve-like members 5 and 6 taper lengthwise and are provided with substantially cylindrical end portions H at the larger ends thereof facing each other which are provided with a plurality of circumferential corrugations l2 therein providing inwardly directed annular ribs within the socket portions formed by said substantially cylindrical portions H also serving as housing means for the springs l0.

Cooperating with said sockets with the inwardly directed annular ribs therein is an in sulating member 13 which is made up of a .body of molded insulating material which can be made of any insulating plastic that has sufficient tensile strength, although transparent plastic material has been found to be the preferred material up to the present time. The insulating member I3 is molded prior to assembly with the sleeve-like members in a generally cylindrical shape with a plurality of annular grooves l4 therein arranged in spaced relation and conforming in spacing arrangement to the ribs formed by the corrugations 12. which are formed in the sleeve-like members after assembly of said insulating member therewith by spinning or otherwise, to thus provide an interlock between the metal sleeves 5 and the insulating body l3. Fibrous reinforcing means is provided for the insulating body I3, said fibrous reinforcement being of insulating material, glass fibres having been found to be particularly useful due to their tensile strength for this purpose.- While separate glass fibres can be used to increase the tensile strength of the molded plastic insulating body, it has been found preferable to use cords made up of glass fibres. said glass fibre cords I! being arranged generally lengthwise of the body portion as shown in Figs. 1 and 2 of the drawings and being laid substantially in parallelism in the plastic material prior to the molding of the grooves H therein.

When the grooves I are molded in the plastic body it, the cords of glass fibres are caused to flow with the material so as to be deformed, providing indentations l 8 in said cords, which anchor the cords in position and interlock certain of said cords with the inwardly directed annular ribs formed by the corrugations l2. Said cords extend from one end I! to the other end ll of the insulating body ll. The deformation of the glass fibre members puts the cords, as well as the molded plastic material forming the body in which said cords are imbedded, under a compression stress when the strain insulator is put under tension in use between the ends I! thereof and the rib formed by the corrugation i2 nearest the mouth or open end I9 of each of the socket portions of the sleeves 5.

Between said innermost ribs in said sockets the strain insulator is under tension in use but the reinforcing insulating fibres take up this tension strain, thus increasing greatly the strength of the insulator over a molded body having no such reinforcing fibres against a tension stress.

Instead of making the reinforcement of separate cords i5 extending in substantial parallelism to each other, the cords Hi can be loosely stranded into a rope indicated generally in Fig. 3 by the numeral 20, and this rope-like member of cords of insulating glass fibres is molded in a body of insulatin material I! in the same manner as the separate fibres shown in Figs. 1 and 2 are molded therein, the plastic insulating material flowing between the cords that make up the rope-like member. In both forms of the invention, said plastic material molds itself in close adjacency to the fibres that make up the cords as will be evident from Fig. 1, filling any recesses between the adjacent fibres to thus provide a strong interlock between the plastic body in which said glass fibres are molded and the reinforcing members.

A strain insulator is thus provided which has an insulating body portion which has great tensile strength, the shear stress portion at each end of which is under compression in use instead of under tension and which has all the electrical insulating qualities that are required of a strain insulator of this character. Obviously the member l3 can be made of desired length and cross-section with the metallic sleevelike members spaced a desired distance apart at their proximate ends i9 so as to provide the proper insulating gap there-between, and other suitable cooperating deformations than the annular grooves l4 and corrugations II can be provided for securing the insulating body to the metallic sleeves, as long as the glass fibres are embedded in the plastic body and said fibres are deformed or oflset at the securing portion of said insulating body to provide an interlock between said fibres and the holding formations on the sleeves.

Having thus described my invention, what I 4 claimisnewanddesiretosecurebylatten Patcntis:

1. In a strain insulator an elongated smooth surfaced body of molded insulating material having a plurality of annular grooves around the same and having a longitudinal reinforcement of a loosely stranded rope of non-absorbent insulating fibre cords of greater tensile strength than said molded material molded therein to surround said cords with said insulating material, said rope beingdeformed at said grooves.

2. In a strain insulator an elongated body of molded insulating material having a, plurality of annular grooves around the same at each end thereof and having a longitudinal reinforcement of spaced glass fibre cords molded therein. said cords being each surrounded by said molded material and being deformed at said grooves.

3. In a strain insulator an elongated smooth surfaced, imperforate, non-absorbent body of molded insulating material having a plurality of annular grooves around the same at each end thereof and having a longitudinal reinforcement of a loosely stranded rope of glass fibre cords molded therein, said rope being deformed at said grooves and each of said cords being surrounded by said molded material.

4. In a strain insulator an elongated smooth surfaced imperforate insulating body portion having a plurality of alternating annular grooves and ribs extending around the same formed therein adjacent the opposed ends thereof, said body portion comprising a mass of insulating material having a longitudinal reinforcement of flexible insulating material of greater tensile strength than said mass embedded therein and united therewith, said reinforcement comprising fibrous members extending substantially longitudinally of said body portion from adjacent one end thereof to adjacent the other end thereof and said reinforcement being deformed at said grooves to provide undulations therein aligning with said grooves providing anchoring means for said reinforcement adjacent the ends of said body portion.

5. In a strain insulator, an elongated smooth surfaced non-absorbent insulating body portion, metallic sleeves having socket portions receiving the ends of said insulating body portion and spaced to provide an insulating gap bridged only by said insulating body portion, said socket portions having circumferential corrugations therein and said body portion having formations therein adjacent its ends complementary to said corrugations, said insulating body portion being composed of a plastic insulating material and insulating fibres of greater tensile strength than said plastic material extending lengthwise of said body portion and enclosed within and united with said plastic material to provide a longitudinal strain resisting reinforcement across said gap, said reinforcement being deformed at said corrugation receiving formations t interlock said corrugations therewith.

6. In a strain insulator, an elongated smooth surfaced non-absorbent insulating body portion. metallic sleeves having socket portions receiving the ends of said insulating body portion and spaced to provide an insulating gap bridged only by said insulating body portion, said socket portions having circumferential corrugations therein and said body portion havin formations therein adiacent its ends complementary to said corrugations. said insulating body portion being composed of a plastic insulating material and glass fibres extending lengthwise or said body portion and enclosed within and united with said plastic material to provide a longitudinal strain resisting reinforcement across said gap, said reiniorcement being deformed at said corrugation receiving formations to interlock said corrugations therewith.

7. In a strain insulator, an elongated smooth surfaced non-absorbent insulating body portion, metallic sleeves having socket portions receiving the ends of said insulating body portion and spaced to provide an insulating gap bridged only by said insulating body portion, said socket portions having circumferential corrugations therein and said body portion having formations therein adjacent its ends complementary to said corrugations, said insulating body portion being composed of a plastic insulating material and corded glass fibres extending lengthwise of said body portion and enclosed within and united go with said plastic material to provide a longitudinal strain resisting reinforcement across said gap, said reinforcement being deformed at said corrugation receiving formations to interlock said corrugations therewith.

JOHN BROWN COOK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,006,040 Alsberg Oct.. 17, 1911 1,006,042 Alsberg Oct. 17, 1911 1,167,125 Sloper Jan. 4, 1916 1,373,576 Thomas Apr. 5, 1921 1,691,005 Burke Nov. 6, 1928 1,782,790 Miller et a1 Nov. 25, 1930 2,014,441 Matthews Sept. 17, 1935 2,202,820 Baird et al. June 4, 1940 FOREIGN PATENTS Number Country Date 216,527 Switzerland Dec. 1, 1941 551,166 Great Britain Feb. 10, 1943