US2688666A - Twist blade switch - Google Patents

Description

TWIST BLADE SWITCH 3 Sheets-Sheet 1 Filed June l, 1950 s w M M A w. E N vV L R A n. u .u l E H. H. M f M --@,L 1 -Lf L-: m w H Z s fa n t Ll T r LV@ i. M i R mm f M4 n n mv om 1 `Nm| QN MN m M. Vv/UIIIIIIIIIIH HH HHN H HlllllllllllhwllJ-Ik l .l u i m Q. wm vw @uw o w uw wv Qn, v w w a. Q. N\ G J Nm. Mm. lAI-IN S Jaw/www ATTORNEYS Sepi: 7, 1954 W, H G|| AND ETAL 2,688,666

TWIST BLADE SWITCH Filed June l, 1950 3 SheetsShee1l 2 lll/lill F /rzf/UGH H TURN/MM ATR 3R XEYS Sept 7, 1954 w. H. GILLILAND ETAL 2,688,666

TWIST BLADE SWITCH 3 Sheets-Sheet 3 Filed June l, 1950 INVENTORS W/LL/AM H. G/LL/LA/vo l. 7 F rzHl/GH H TURN/MM f" BY JM, www

ATTORNEYS` of the blade.

`between the blade and jaw contacts. severe icing conditions are present, this added Patented Sept. 7, 1954 UNITED 4STATS PATENT .OFFICE TWIST BLADE SWITCH William H. Gilliland and Fitzhugh H. Turnham, rBirmingham, Ala., assignors to USCO Power Equipment Corp., Birmingham, Ala., a. corporation of Alabama Application June 1, 1950, Serial No. 165,546

(Cl. 20o- 48) 10 Claims.

This invention relates to high voltage switches ofv Ythe twist blade type in which the switch blade .switches in the transmission of high amperage current.

In prior switchesv of this kind usedr to control higlrsamperagea itl has been the practice to employ a heavy shunt-'at` the hinged end of the switch to accommodate the very high amperage currents and a relatively heavy, stiff, fixed jaw contact structure. 4As an alternative construction, it hasalso been proposed to replace the heavy shunt with a jaw-type hinge contact assembly similar in construction to the contact assemblyV employed at the outer vorswinging end In eithercase, substantial resistance to yblade twist is-:developed necessitating l high applied: operating forces andvuneven pres-r surecontact often. results due to Vmisalignment Where resistance may be of sufficient magnitude to prevent eiective yoperation -of the. switch.

Accordingly, 4it is ageneral object andpurpose .of vthe present invention toprovide novel blade contact assemblies comprising a cylindrical or spherical contact at the hinge end of f the blade which is at all times Aresiliently engaged with a mating stationary contact which offers a minifmum resistance to rotation of the blade and yet provides ample contact area and mass for transmission of the heavy current in the desired manner and a self aligning jaw contact assembly for engagement by thev swing end oi the blade.

It is a' further object ofthe invention to provide a novel hinge contact assembly which assures positive contactr between the switch blade Iand the hinge base at all times so vthat the contact has full capacity in all positions of the switch blade even during periods of extensive arcing in l opening and closing the switch.

It is a further object to provide a novel hinge contact assembly which is simple in design, comprises a minimum number of structurally rugged parts, and is inexpensive to manufacture and assemble.

In the conventional jaw-type stationary contact for the outer end-of` the switch blade, par- ..2 ticularlyV after a -period of use, accurate alignment. between the switch blade and the station- `ary contact often cannot be maintained. This is particularly true where ythe' switch blade is of :substantial length. -As a result-there may be considerable variation in the pressure with which the blade engages theopposing jaws of the contact and consequently uneven wear von one contact surface. In the conventional jaw contact construction this situation can ybe remedied only bymechanical bending of the jaws y or complete resetting -of the contact, neither of .which has proved to .becwholly satisfactory in practice.

Accordingly, it is a further object toprovide anfmproved jaw-type outer contact assembly for aswitchv bladek switch which is self-aligning.

Itis a further object to providean improved outer contact assembly in which the4 engaging pressure may be easily .and accuratelywadjusted.

It isa further object toprovide an improved vcontact assemblyin which the-pressure of the opposing contact jawsis automatically maintained in substantial equality.

Other objects and advantages will/,appear as the descriptionr proceeds -inconnection with the accompanying drawings in which:

Figure 1 is a sideelevation of a switch `illustrat- 4ingfone embodiment of the improvedwhinge contact construction of this invention;

Figure V2 is an enlarged sectional vView .taken along line 2-2 Aof Figure 1;

contact assembly taken along line 4-4 of Figure- 1;

Figure 5 vis a side elevation partly inv section of a modified embodiment of the' hinge contact assembly of this invention;

Figure 6 is a fragmentaryy plan View taken along line 6 6 of Figure 5;

Figure 7 is a fragmentary side elevationfof still another hinge contact assemblyl embodying the presenty invention; and

"Figure 8 is a fragmentary plan View taken along line 8-8 of Figure' 7.

The present vinvention isconcerned only with contact assemblies. The general arrangement of the components ofthe switchV and the operating mechanismv therefor are disclosed` and claimed in the copending application of William H. Gilliland and Fitzhugh H. Turnham, Serial No. 137,618,

rled January 9, i1950,fand entitled High Voltage Switch Assemblies. Therswitch is here described 3 only in so far as it is necessary for a complete understanding of the construction and operation of the improved hinge contact assembly.

Referring now to Figures 1-4 of the drawing, I indicates a base on which are mounted a fixed insulator II vcarrying jaw-type contact I2 and arcing horns I3, a fixed insulator I4 supporting the hinge assembly I5, and a rotatable insulator I 6 carrying operating arm I1 at its lower end and operating linkage, indicated generally at I8, at its upper end. As best seen in Figure 4, extension I9 of switch blade 28, is formed into rectangular shape provided with a reinforcing insert, and is resiliently and. frictionally clamped between op posed contacts I2. While any suitable construction may be employed for contacts I2, the self aligning contact of this invention to be hereinafter described is preferred. Blade 29 is journalled at its end opposite contacts I2 in sockets 22 and 23 which are integral parts of bracket 24 (Figures 1 and 2) which is pivotally mounted on pin 25 for vertical rotation thereabout.

The mechanism for twisting and lifting switch blade 2l) includes operating arm I1 and crank 25 mounted for co-movement on shaft 21 which is journalled in bearings 28 and 29 respectively mounted in base Ii) and a conductor arm 30 interconnecting insulators I4 and I6. Pull rod 3| is connected by universal joints 32 and 33 to crank 26 and rocker arm 34 respectively. Legs 35 of rocker arm 34 are pivotally mounted on stub pins 36 mounted in ears 31 of fixed base 38. Lifting link 39 is pivotally mounted on pin 40 on bearing 22 and pivotally mounted at its opposite end on pin 4I in rocker arm 34. Also pivotally mounted on pin 4I is blade twisting link 42 which is connected through universal joint 43 to the free end of crank arm 44 which is rigidly secured to switch blade 20.

The operation of the blade twisting and lifting mechanism thus far described is as follows.

When operating arm I1 is rotated to open the switch, rocker arm 34 together with pin 4I will be rotated in a counterclockwise direction about pin 35. Since both lifting link 39 and twisting link 42 are pivotally secured to pin 4I at their upper ends and as their opposite ends are respectively disposed substantially radially inwardly of and substantially directly below pin 4I, link 39 will initially rotate about pin 49 without imparting any appreciable lifting movement to pin 40 or its supporting bracket 24 because of the substantial coincidence of the arcs of rotation of pin 4I around pins 36 and 40. Link 42 meanwhile since it extends substantially directly downwardly from pin 4I will initially be raised bodily upwardly due to the axial application of force through pin 4I. As a consequence, the angular relationship of links 39 and 42 will be decreased while link 39 is maintained in tension and link 42 imparts an upward force to universal joint 43. Since downward movement of pin 4I) is also prevented by the closed condition of switch blade 20 and contacts I2, the force resulting from the folding of links 39 and 42 is effective to rotate blade 20 in sockets 22 and 23 twisting switch blade 28 through substantially 90 degrees to disrupt the frictional bearing pressure of the blade contacts I2 and position the blade in a substantially vertical plane between the contacts. In the further upward swinging movement of the rocker arm the arcs of rotation of pin 4I around pins 36 and 40 separate imparting a lifting movement to link 39. The angular relationship of the links at this time is maintained and the bracket 24 with its journals 22 and 23 is swung upwardly through an arc of approximately degrees about the axis of pin 25 to dispose the switch blade in the open position.

The above described operation is reversed when the switch is closed by rotation of the operating arm I1 in the opposite direction.

It will be apparent from the foregoing that the ease of operation of the switch during initial twisting movement of the switch arm is dependent wholly upon the resistance to twist offered by the contacts at the inner and outer ends of switch blade 20. As aforementioned the present invention is concerned with minimizing the resistance to twist offered by the inner or hinge contact without impairment of the effectiveness of the contact at this point.

Referring now to Figures 2 and 3, which illustrate a preferred embodiment of the improved hinged contact assembly, 41 indicates a hollow spherical stationary contact element rigidly attached to base 38 by bolts 48. Pin 25, on which ears 5D of bracket 24 are mounted, passes through a diameter of contact 41, Bearings 22 and 23 carried in bracket 24 are thus maintained in spaced relationship to contact 41'and are rotatable about the axis of pin 25. A female contact 5I is disposed within the hollow `journalled end of blade 29 and rigidly secured thereto as by pin 52. A press t is preferably maintained between contact 5I and blade 20 to assure positive contact between the members over a large surface. A spherical recess 53 having a radius equal to that of the outer surface of contact 41 is provided in an enlarged portion 54 of contact 5I protruding beyond the end of blade 20. To assure positive engagement of the mating surfaces of contacts 41 and 5I, a spring 55 is compressed between shoulder 56 of contact 5I and bearing 22,` bearings 22 and 23 being spaced sufficiently to allow axial movement of link 44 therebetween and axial movement of blade 29 and contact 5I into engagement with contact 41. This hinge contact assembly is especially advantageous in that it minimizes the resistance to rotation of the switch blade 20 and assures positive contact over a large area at all times regardless of the position of switch blade 20 and contacts I2. Accordingly, even though arcing occurs between blade 20 and contacts I2 during opening and closing movement of the switch, full electrical contact is always maintained at the hinged end of the switch.

Referring now to Figures 5 and 6, which illustrate an alternative hinge contact construction, a spherical male contact member 51 forms an extension of a stem 58 which is received within the hollow end of switch blade 20 and rigidly attached thereto as by pin 59. To facilitate assembly, contact 51 is purposely made small enough so that it may be passed through bearings 22 and 23 after being assembled on blade 28. Stem 58 and blade 20 preferably have a press fit to assure full and tight surface engagement between them. Contact 51 is frictionally received in spherical recesses 6D formed in a pair of opposing contacts 6I disposed between ears 50 and rigidly mounted on base'38 as by bolts 62. The frictional engagement between Contact 51 and contacts 6I is adjustably maintained by a pair of spring washers 63 which are held in resilient engagement with the outer surface of contacts 5I as by bolts 64. Nut 65 and lock nut 66 are provided to adjust the engaging pressure between contacts 6I and contact 51.

Figures 7 and 8v illustrate a: third embodiment of the hinge contactV construction which is similar in all respects to the embodiment ofiFigures'B and 6 described aboveV except that. switch blade 20 is extended so as tobe received between apair of opposing contacts formedfby U-shaped member 61 and thus forms one oil the contact elements. Spring washers 63, bolt 64 and nuts 65 and 66 similar to those described in connection with Figure 7 are provided to maintain anadjustable frictional engagement-between the contacts. The arcuate section 6B at the lower ends of contacts 61 is preferably held in an arcuate seat 68' formed on base 38 by clamping members 69 and bolts 1I threaded into seat t8 of base 38.

Referring again to Figure 4, each of the two pairs of contact jaws I2 is preferably formed from a single relatively flexible. piece of metal bent into U-shape and having outwardly flaring portions at its upper end. The bridge section 12 of each pair of jaws I2 is clamped between a lower' clamping member 13, which is rigidly attached to insulator II, and an upper clamping member 14, as by bolts 14. Clamp 13 is provided with a centrally located upwardly extending ear 15, which is apertured to receive a loosely iitting ypin 16. Mounted on pin 1G are spaced lugs 11 attached to the lower edge of a plate 18. which is received between the longitudinally spaced pairs ofcontact jaws I2, as shown in Figure l. A pair of opposing spring housings 'i9 form an integral part of plate 18 and are positioned outwardly of both pairs of contacts I2v (Figure l). 'A spring 2l disposed in each housing 19 is compressed between a bearing platet which engages the respective two adjacent contacts i2, and bearing plate 8| received within housing 19. An adjusting screw 82 and lock nut 83 are provided to regulate the respective compression springs 2|. A pair of stops 84' are provided on plate 18 to limit the inward movement of contacts I2.

In operation, assuming for example that the switch blade 2li' is slightly out of alignmentA to the left, the engaging pressure on the left side of extension Ie will initiallybe greater than. that on the right side. This will result in a slight displacement of the left contact jaws i 2 to the left, increasing the compression of the left spring 2l. Since plate 13 is free to pivot about pin 16, it will be rotated slightly in a counter-clockwise direction until the compression of the opposing spring 2| is substantially equal. Thus, the entire contact assembly will tend to come into automatic alignment with the switch blade 2Q.

It will be understood that the degree to which the contact jaws are self -aligning depends in large measure on the flexibility of the contact shoes. If, as in the prior art, the jaws are made suiiciently rigid to furnish the entire contact pressure between the jaws and the blade contact, the contact jaws or shoes will absorb the excessive contact pressure due to misalignment of the blade and impose a high resistance to movement of the blade to fully closed or opened position. This invention, therefore, contemplates the use of relatively light, flexible jaws or shoes and self compensating opposed pressure springs 2| which are brought into play in event of misalignment to permit relatively free and successive lateral movement of the jaws in the same direction to a position in substantial alignment with the blade. On the other hand, the shoes must possess sufficient rigidity to prevent deformation beyond their elastic limit. In practice, the jaws or shoes may have any degree of ilexibility above that necessaryl .to avoidy permanent deformation but less than that which will-prevent relatively free lateralSdisplacement-by theblade moving to closed position, the optimumflexibility being determined in individual cases` with regard to the f size of theswitch, the twist bladaami' the amount' of use required .in service.

It is also to. be noted that in the'completely closedposition of the blade 20, shown in Figure 4, extension I9 is oenteredwith respect to spring 2 I. Consequently, thecontact pressure is exerted directly through the center line of thexcxtension, thereby assuring uniformity ofthe contact pressure and minimizing thei objectionablefeffects of bending or Wear of .the contact jaws I2.

'It is feltr that ytheoperation of the various hinge contact assemblies will be obvious from the foregoing description.

It is to be noted that in each construction the hinged contacts .arein resilient engagement at all times, that the areaof contact isA constant in all positions of .the-'switch armthat the contacts are self cleaning because of the rotation about two axes in each operation of the switch, and thatA in eachof the constructions the frictional resistance to. twisting and swinging Vmovementiof the switch arm is minimized.

The invention` may `be embodied in other speciiic forms without department from the spirit-or essential characteristics thereof, the present ernbodiments are therefore -to bey considered in all respects as illustrative `and Lnot restrictive, the scope of vthe invention being indicated bythe appendedv claims ratherV than 'by'L the foregoing descriptionl and.` all changes which come within the meaning and range Yof equivalency of the claims are therefore 'intended to be embraced therein.

What is claimed and desired to be secured vby United States. Patent is:

1.. An electric transmission line switch comprising a'pair'of spaced, xed supporting insulators; a fixed bifurcated contact mounted on lone of said .fixed insulators; a twistb-lade switch pivotally and rotatably mounted on said other insulator and adaptedtobe rotated about its longitudinalaxis to establish firm contactwithsaid xed bifurcated contact and to swingaround its pivotal` axis into and out' ofv contact with' said fixed bifurcated contact; a second stationary contact mounted on said-other insulator and having a contact portion in transversely aligned relation to the pivotal axis of said switch blade; and contact means on said switch blade of circular cross-sectionI in a plane normal to the axisy of said switch blade rotatably and pivotally movable therewith and comprising an elongated portion extending into the pivoted end of said switch and having an enlarged contact end protruding axially of said switch blade into cooperating engagement with said contact portion of said second stationary contact and adapted to establish contact therewith in full contacting capacity and constant contact area in all positions of said switch blade. j

2. The combination defined in claim 1 wherein said switch blade is mounted for limited axial movement in a pair of axially spaced journal sockets and a compression spring is mounted in encircling relation to the end of said switch blade with its opposite ends respectively engaging said enlarged contact end and the adjacent one of said spaced journal sockets to resiliently urge said switch blade and its attached contact means axially into rm engagement with said second contact stationary contact.

3. A hinge contact assembly for a twist blade switch comprising a blade contact having an elongated portion extending into the pivotal end of said switch blade and an enlarged contact end protruding axially from switch blade end and providing a spherical contact area coincident with the longitudinal axis of said switch blade; and a stationary terminal contact element adapted to continuously engage said blade contact and having a reversely mating spherical contact area the center of which is coincident with the pivotal axis of said switch blade and the 1ongitudinal axis of said switch blade whereby, upon pivotal and twisting movement of said blade, said mating contact areas are maintained in full sulface contacting capacity and constant Contact area.

4. The combination defined in claim 3 together with means to resiliently urge said contacts into firm mating engagement to assure good electrical contact and a self-cleaning rubbing contact between said contacting areas.

5. The combination defined in claim 4 wherein said means for resiliently urging said contacts into engagement comprises a compression spring adapted to urge said switch blade and said blade contact axially into engagement with said stationary contact.

6. The combination defined in claim 4 wherein said stationary contact comprises a pair of laterally spaced arms having oppositely inwardly facing depressions and spring means is provided comprising a transversely extending headed bolt member extending freely through said spaced arms, a pair of dished spring washers respectively disposed in contact with said head and on its opposite end, and a nut threadedly associated with said opposite end and adapted to be threaded thereon to tension said spring washers to resiliently urge said arms inwardly into contact with said blade contact.

7. The combination defined in claim 4 wherein said static-nary contact comprises a ball shaped member and said resilient means comprises a compression spring disposed in encircling relation to said switch blade end with one end in contact with said enlarged contact end so as to urge said blade contact axially into engagement with said ball shaped member.

8. In an electrical twist blade switch having a hinge end contact assembly: a swing end jaw contact assembly for receiving the swing end of said blade comprising highly flexible laterally spaced jaws and means associated with said spaced jaws to automatically shift said respective jaw contacts to properly receive the swing end of said blade and thereafter maintain uniform pressure engagement between each of said jaws and said blade in the closed position of said switch whereby proper contact is assured in spite of slight misalignment of said twist blade and said contact assemblies and the number of opening and closing movements of said switch.

9. 1n an electric twist blade switch: a bifurcated relatively stationary swing end contact; a blade contact movable into and out of engagement with said stationary contact; and means to automatically shift said relatively stationary contact with respect to said blade contact to assure substantially equal pressure contact between said blade contact and the arms of said bifurcated contact when said blade is moved into engagement with said stationary contact.

10. In an electric twist blade switch: a swing end contact assembly comprising a blade contact, a pair of opposed jaw contacts adapted to engage opposite sides of said blade contact; respective resilient means adapted to control the engaging pressure between said blade contact and each of said opposed jaw contacts; and means responsive to engagement of said blade contact with said opposed jaw contacts to vary the pressure exerted by one of the said pair of resilient means in response to a variation in the pressure exerted by the other of said pair of resilient means.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,560,165 Johnson Nov. 3, 1925 1,831,843 Corni-leid Nov. 17,1931 2,363,307 Florschutz Nov. 2l, 1944 2,453,011 Graybill Nov. 2, 1948 2,531,165 Scheurmeyer Nov. 21,1950 2,545,940 Caldwell Mar. 20, 1951

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