US2289197A - Insulator - Google Patents

Description

Patented July 7, 1942 I INSULATOR Ruel O. Jones, Wilknsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania.

Application November 29, 1939, Serial No. 306,691

2 Claims.

This invention relates to insulators, and particularly to insulators of the type employed for mechanically connecting a plurality of movable rod members while electrically insulating them from each other.

In certain types of electrical apparatus, and particularly pneumatic circuit makers and breakers, it is desired to electrically insulate the moving contact member from the actuating mechanism and to provide for protecting the actuating mechanism from any arcing incidental to the making and breaking of a circuit. Many different types of insulators have been employed for this purpose, but have not proven to be satisfactory in service. Failures of such insulators are primarily due to the lack of strength in the insulator, the known insulators not being sufliciently resistant to th'e shocks encountered during operation of the actuating mechanism. In addition to the requirement of high strength, the insulators used for this purpose act as a shield to prevent the arc from flashing to grounded parts of the apparatus during short circuits.

An object of this invention is to provide an insulator which is suitable for mechanically connecting a plurality of rod members while electrically insulating them from each other.

Another object of this invention is to provide an insulator having receptacles electrically insulated from each other for receiving rod members which are to be mechanically connected and a reenforcing member of insulating material so positioned with respect to the receptacles as to retain them in position for receiving the rod members, the receptacles and reenforcing member being integrally united to give a strong structure.

Other objects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawing, in which:

Figure 1 is a view in elevation and partly in section of the actuating mechanism of a pneumatic circuit maker and breaker embodying the insulator of this invention;

Fig. 2 is a top plan view of the insulator of this invention;

Fig. 3 is a side elevational View of the insulator constructed in accordance with this invention; and

Fig. 4 is an end view of the insulator of this invention shown partly in section, as taken along the line IV-IV of Fig. 3.

Referring to the drawing and particularly Fig. 1 thereof, the insulator I0 of this invention is illustrated as employed as the piston insulator in the actuating mechanism of a pneumatic switch having a stationary contact member I2 and a movable contact member I4. As illustrated, the actuating mechanism of the switch comprises a plurality of elements consisting of an air cylinder assembly I6, the insulator I0, a V-type link I8 connected through a rod member 2i] to the insulator I0, as will be explained more fully hereinafter, and a carrying member 22 for the movable contact member I4 pivotally mounted to the V-type link I8, as by means of the pin 24.

The air cylinder assembly I6 is of standard construction and consists of a chamber dened by the Wall members 26 within which a piston 28 and piston rod 29 are assembled and disposed for movement vertically when air is admitted to the lower end of the chamber below the piston through an air inlet pipe 30. In order to provide for substantially instantaneous movement of the piston 28 to eiTect substantially instantaneous separation of the contacts I2 and I4 when the air is removed from the air cylinder, a spring member 32 is assembled in the chamber I6 about the piston rod 29 and is biased to move the piston 28 downwardly to its inoperative position. In order to limit the extent of movement of the actuating mechanism, a suitable stop 34 is provided within the air cylinder for abutting against the piston 28 to prevent excessive movement thereof in an upward direction. The air cylinder assembly I6 is suitably carried, as by means of the bracket 3, on any suitable base 38.

In assembling the actuating mechanism, the insulator I0 is mechanically connected to one end of the piston rod 29 in a manner hereinafter described while the rod member 2U is mechanically connected through the V-type link I3 tothe other side of the insulator I0.

Upon admission of the air to the air cylinder assembly I6, the piston 28 is moved in a vertical direction, carrying with it by means of the piston rod 29 the insulator I0, rod member 20 and V- type link I8, which in turn, carries the carrying member 22 for the movable contact member I4 upwardly until the movable contact member I4 engages the stationary contact I2. Upon engagement of the contact members, the carrying member 22 is pivoted about the pin 24 in a clockwise direction and the lower portion of the carrying member 22 engages the spring 4I) assembled in any suitable fashion within the V-type link, such rotation of the carrying member 22 permitting a rolling contact between the contact members I2 and I4.

If for any reason the air supply to the air cylinder I6 is cut off, the actuating mechanism moves downwardly as hereinbefore referred to, due to the bias of the spring 32 within the air cylinder assembly to eiiect the disengagement of the contact members. When the actuating mechanism starts to move to separate the contact members l2 and it, the spring lill carried by the V-type link biases the carrying member 22 for the movable contact member I4 in a counter-clockwise direction, giving a rolling movement of the movable contact member on the stationary Contact members as they disengage. The piston and air cylinder assembly are protected fromk any arcing between the contact members during the disengagement thereof by the insulator l,

As is quite evident from the foregoing, the insulator lil must not only protect the piston rod and air cylinder assembly from arcing effects and electrically insulate them from the movable Contact member assembly, but since the disengagement ofthe contactwmembers is fast, the insulator Ylil must have sufficient'strength to withstand the shocks'encountere'd in actuating'the movable contact member i4 into and out of en- Vgagement with the stationary contact member I2.

In order to provide an insulator lil suitable for thev purposes hereinbefore described, it is desired to employ insulating material, such as synthetic resin in the insulator. The different types of known synthetic resins, such as phenolic condensation products, urea and thiourea resins of themselves, however, do not have the strength necessary for the particular application described. Referring to Figs. 2 and 3 of the drawing, the insulator of this invention is illustrated with the details thereof being shown specifically in Fig. 4.

As illustrated, the insulator lil comprises a plurality of elements molded into an integral structure under heat and pressure. As shown in Fig. 4, a plurality of receptacles 42 and 44, comprising metallic inserts for receiving the rod member 2li and the piston rod 29 oi the air cylinder assembly of Fig. 1, are positioned in aligned and spaced relation with respect to each other. These receptacles or inserts have internally threaded surfaces for engaging with the rod members to be connected. In order that the receptacles 42 and 445 may be retained in position in the insulator, their outer walls are provided with a plurality of grooves 45, the purpose of such grooves or roughened surfaces of which will be explained more fully hereinafter.

In positioning the receptacles 4.2 and 44, in order to maintain them in spaced relation to and electrically insulated from each other, a preformed insert 48 of insulating material, such as synthetic resin, is disposed between the adjacent ends of the aligned receptacles. This insert may be either in the uncured or cured state, as desired. If cured, it is desired that its outer surfaces be roughened similar to the outer surface of the receptacles which it maintains in spaced relation and insulated from each other.

In order to strengthen the assembly, a tube i] of insulating material is positioned about the aligned receptacles 42 and 44 having the insert 48 therebetween. This tube is formedof woven fibre glass of the type recently developed the fibres having an average diameter of about .0003 inch, and which in its woven form is iieible and has anexceedingly high strength.4 In forming the tube 5i), the woven fibre glass inv the form of tape or cloth, is wound about asuitable mandrel until the wound layers have a thickness of about of an inch, the tube having a length equal to that oi the aligned receptacles 42 and i4 with the insert 48 therebetween.

In order to form the tube 5@ of woven fibre glass and the receptacles 42 and 44 and insert 48 into an integral unit, the tube with the receptacles and inserts therein is positioned in a suitable mold having a configuration of the desired insulator. A quantity of synthetic resin is then disposed about the tube 591i, after which the mold is closed and subjected to sufficient heat and pressure for a period of time suflicient to effect the molding of the synthetic resin to form the body 5i of any predetermined shape about the tube In molding the synthetic resin, it is round that the resin completely and thoroughly impregnates the tube 5@ of woven fibre glass, and under the action of pressure is forced, together with a portion of the fibre glass, into the grooves lit, which form the roughened outer surfaces of the receptacles 42 and 44. In practice the tube 5@ is usually impregnated with the resin before it is positioned about the receptacles in order to insure an adequate supply of resin in thetube for bonding it to the receptacles during the molding operation. v

In addition to bonding the iibre glass tothe receptacles, the synthetic resin is bonded securely to the insert 43 between the receptacles 42 and 44. Where the insert '43 is of uncured resin,V- it is foundl that underthe action of the heat and pressure encountered'during the molding operation, the insert 43 is completely cured, a portion of the resin combiningwith the contacting surf.; faces of the tube iand with'the'synthetic resin of the body portion 52 whichA impregnates the tube 5i). If the insert ES is formed of the cured resin it is found that in molding the insulator, the resin of the body portion impreg'nates the tube of fibre glass and securely bonds it to the preroughened outer surfacesinot shown) of the cured insert.

In molding the insulator Ill, an arc shielding flange 54 ismoldedI as an integral part'of the body 52 of synthetic resin'and extends outwardly therefrom radially to the aligned receptacles 42 and 44. As is evident rfrom IFig. fin the particular embodiment'illus'tratedf webs 56 of the synthetic resin are also molded integral with the body portion'to support the flange 54. r'I'he fiange 54 extends outwardly fora suicient distanceto protect the piston rod which is threaded into the receptacle 44 and the air cylindervas'sembly from any arcs encountered. *As will Nreadily beap'preciated, the body portion 52 of theYV insulator 'can be molded into any predetermined shape, depending upon the mold employed in molding the insulator, although in all cases it is preferred that the insulator carry the outwardly extending arc shielding flange 54. Y W v Where desired, a depending portion 5 8 can also be molded to the outer edge ofthe flange'r54 as illustrated in the drawing, and be provided with inserts 6d for receiving contactni'embers 62,"as illustrated in Fig. l. rThe contact members .62 cooperate with the Contact yarr'r`1"t 4 for giving a protective interlock with'associated contaotors, not shown, with which the described l'contactor is employed. The control circuits oty theintrlocking system are not illustrated sincethey do not form a part of this invention.

In a specific example of the molding of an insulator in accordance with this invention, with the tube 50, receptacles 42 and 44 andin'sert 48 positioned as described hereinbdefore, and the synthetic resin disposed thereabout, the mold is closed, after which a temperature of between 175 and 180 C. is applied for a period of time of about 50 minutes while simultaneously subjecting the assembly to a pressure of from 20 to 30 tons per square inch. When removed from the mold, it is found that the molded insulator has a mechanical strength superior to that of any known constructions, the synthetic resin and fibre glass cooperating with the roughened surfaces of the receptacles to give an extremely strong integrally molded insulator.

Not only does this insulator have the increased strength over known insulators, but it also has the advantage that in service, it will not lose the mechanical strength due to any deterioration of any of the materials employed. This is because the bre glass tube employed as the reenforcing agent in the insulator has high strength in tension and compression, is resistant to shear and will not lose its strength when subjected to ternperatures above the ambient temperature, as is the case where other brous materials are employed. Further the tube of woven fibre glass is of itself an excellent insulator and cooperates in the insulator to not only give it the required mechanical strength, but also to give it high dielectric strength adjacent its metallic portions.

Although this invention has been described with reference to a particular embodiment thereof, it is, of course, not to be limited thereto eX- cept insofar as is necessitated by the description hereof and the appended claims.

I claim as my invention:

1. An insulator for connecting a plurality of rods comprising, metallic receptacles disposed in aligned and spaced relation to each other for receiving the rods, the metallic receptacles having roughened outer surfaces, an insert of synthetic resin disposed between the aligned receptacles for electrically insulating them from each other, a tube of woven bre glass disposed about the aligned receptacles and insert therebetween and in physical contact with the roughened surfaces of the receptacles, and a body portion of synthetic resin consolidated into a hard infusible mass of predetermined shape about the nbre glass tube, the mass having an arc shielding flange as an integral part thereof extending outwardly therefrom radially to the aligned receptacles, the synthetic resin impregnating the tube of fibre glass to bond it to the roughened surfaces of the receptacles and to the insert to give an integral structure.

2. An insulator for connecting a plurality of rods comprising, metallic receptacles disposed in aligned and spaced relation to each other for receiving the rods, the metallic receptacles having roughened outer surfaces, an insert of synthetic resin disposed between the aligned receptacles for electrically insulating them from each other, a tube of woven fibre glass disposed about the aligned receptacles and insert therebetween and in physical contact with the roughened surfaces of the receptacles, a body portion of synthetic resin disposed about the libre glass tube, an arc shielding flange disposed about and eX- tending outwardly from the body portion and radially to the aligned receptacles, and ribs disposed between the arc shielding ange and the body portion in spaced relation about the body portion for supporting and strengthening the flange, the body portion, ange and ribs being of synthetic resin consolidated into an integral hard infusible structure about the fibre glass tube, the synthetic resin of the body portion impregnating the tube of fibre glass to bond it to the roughened surfaces of the receptacles and to the insert to give an integral structure.

RUEL C. JONES.

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