US1850703A - Electric switch - Google Patents

Description

March 22, 1932. A. E ANGOLD ELECTRIC SWITCH Filed May 9, 1928 3 Sheets-Sheet 1 A. E. ANGOLD l 850,703'

ELECTRIC SWITCH Filed May 9, 1928 3 Sheets-Sheet 2 FIG. 3

Mamh ZZ, 1932. A. E. ANGOLD 1,850,703

ELECTRIC SWITCH Filed May 9, 1928 3 Sheets-Sheet 3 I Jnz/pnfor,

ARTHUR ERNEST" ANGOLD, F BIRMINGHAM, ENGLAND, ASSIGITOR TOtTHE GENERAL ELECTRIC COMPANY, fLlMlTED, OF LONDON, ENGLAND Patentecl M ar. 22, 1932.

Parser FF-HGEI ELEornro swrrcn a neatmn'fileanay e, ieesysermi No. even 49mm in Great Britain June 27,1927- This invention relates toelectric switches, for example, circuit breakers adapted to be opened byio'rce stored during the closing thereof, and is particularly useful in connec- 'tion with switches which in service carry relatively'large currents. One object of the inventionris to provide reliable contacts which will not'become damaged by overheating, another objectEis to provide an improved contact comprisinga' plurality of separate elenientswhich individually may readily be renewed or changed.

Iii the accompanying drawings, showing the switches with parts thereof omitted, Figure 1 is a sectional side elevation of one form of switch on the line 1-1 of Figure 2; Figure 2 is a plan view of Figure 1; Figure a sectional side elevation ofanother form of switch on the line 111-111 of Figure 4; F igure 4'is a. plan view of Figure 3 with parts bro-ken away'ywhilst Figure 5 "shows aside elevation'of a switch with a modified form of retaining member in section. large; 1, 3 and 5 parts of the moving switchcontact are shown in the positions occupied when "the switch is closed by full lines, in the posi- 'tions occupied when the switch being closed and has just reached the position in which the moving contact first bridges the fixed contacts by short chainlinesand in the positions occupied when the switch is open by long chain lines. r

In the drawings the switch is provided with fixed contacts 1 andQinade of solid copper blocks insulatingly mounted upon the supporting member 40 and adapted to be bridged I by a moving contact formed of copper blades 3 that 'are mounted on a supporting member in the form of a bar 4 and that are acted upon by steel rod biassing springs 5. The bar 4 forms partof a: frame including two side members 7 between which the bar extends and to which the bar is rigidly securedg Held to the supportingmember 40 1s a bracket'52 formed with two arms-41'provided with pivthe arms 41.

tension spring 45 to bias the inoving switch contact to the open position.

'Pivoted at 47 to the arms 410i the bracket 52 iscan-operatinglever 48 provided with a handle 51 and acting betweenthe end of the lever remote from the handle and pivots 46 formed at the ends of the bar 4 are the links 50., In the closed position ofthe switch the a toggle formed by the lever 48 and link is slightly overset, but movement of the, lever is preventedby a'stop 49 extending between If, however, the lever 48 is turned slightly in a counter clockwise direction away from the stop the spring 45 causes the toggle to collapse and rotates the side,

members 7 quickly in a clockwise direction to the open position. If thelever 48 isthen rotated in a clockwise; direction back to the positlo-n in which it engages the stop 49 the S1Cl8Hl8-1Tlb61$ 7 are forced to rotate in a counterclockwise direction against the force withthe longitudinal teeth 8 the sides of which converge at an angle of about 60,

whilstthe ed es 9 of the blades 3 adjacent to "the fixed contacts are made wedge shaped,

the angles of the wedge beingequal to the angles between opposite'faces of the teeth-8. The. wedge shaped edges 9 are blunt so that,

the edges do not extend to the roots ofthe teeth 8,-whilst the thickness of blades 3 is. less than the pitch'of "teeth 8 and there are substantial air gaps 10 between the teeth] In Figs. 1 and 20f the drawings the pivots 6 are constituted by parts of a spindle 11 extending between the'arlns 41 of bracket 52 and rigidly attached to and extending between the side members 7 is a cross piece 13. Secured to cross piece 13 and projecting therefrom are the four springs 5 ofinv'erted L-shape, one for each blade3. The end of the short limb 14 of each springfi engages ina socket 15 formed inthe blade at a-point thereof about midway between the fixed contacts 1 and'2, and thereby positions the blade longitudinally on bar 4. A short distance above the sockets 15 the blades '3 are pierced by circular holes 16 considerablylargerthan the roundbar 4 which-1s threaded through the holes 16 and is secured rigidly to the side members 7. The blades 3 are also provided at their lower ends with recesses 17 for avoiding interference of the spindle 11 therewith. Moreover, the front part 18 of the upper edge of the cross piece 13 acts as a stop with which,

during the later'part of the closing movement of the switch, the ends 19 of the blades contact, thus limiting longitudinal movement of the blades'3 relatively to the side members 7, and causing the blades to move lengthways relatively to the fixed contacts 1 and 2.

When the switch is opened by rotating the side members 7 about the pivotal axis 6, the springs press the blades 3 against the fixed contacts ,1 and 2 until the bar 4 reaches the back edges of the holes 16 in the blades, when the said member draws the blades away from the upper fixed contact 1, and the springs 5 acting on blades 3 at socket between the bar 4 and contact 2 cause theblades 3 to pivot aboutthe bar 4, and maintain the lower ends of the blades pressed against the bottom edge of the lower fixed contact 2, 'thusavoiding sparking thereat.

When the side members 7 are rotated in,

the opposite direction to close the switch, the wedge shaped contact faces of the blades 3 after preliminary movement of the blades fully engage between the teeth 8 of the lower fixed contact 2, and at the same time engage between'the teeth 8 of the upper fixed contact 1, after which the bar 4 moves away from the back edges of the holes 16 in the blades, the 5 rings 5 that are already strained are furtier strained, and the full force thereof is effective in pressing the blades against the upper and lower fixed contacts. During the closing of the switch, since the movement of cross piece 13 has a component in an upward direction, movement of the blades 3 occurs lengthways relatively to the fixed con .tacts 1 and 2, thereby giving a self cleaning action to the switch contacts. The extent of the rubbing movement between the contents depends on the distance of cross piece 13 from the .axis of rotation 6 thereof.

An alternative way of causingsuch lengthways movement of the blades relatively to the fixed contacts would be to form the holes '16 in the blades through which the bar 4 passes as sloping slots,.the arrangement be ingsuch that the bar engages the upper ends of the slots when the switch is open and the lower ends of the slots when the switch closed, thus causing the blades to slide upwards during the closing movement, and to rub on the fixed contacts 1 and 2.

c In Figures 3, 4 and 5 each blade 3 has riveted to its sides two plates 24, formed with hooks 25, and lugs 26, that together with the hooks help to position the springs 5. The upper end of each spring is for-med with a head 27 which engages a small recess 28 in the back edge of the associated blade, whilst the bottom end of each spring is formed with a tail 29 that bears against the said edge of the blade. Each spring moreover, slidingly fits between the plates 24 riveted to the associated blade, and the greater part of the length of the spring is spaced from the back edge of the blade. The springs 5 near the mid points in the lengths thereof engage with the bar 4 formed with grooves 30 in which the springs find seatings, whereby the blades are positioned longitudinally on bar 4.

The hooks 25 are provided with upper and lowerrsurfaces 31 and 32 which loosely engage the upper and lower surfaces of the bar 4. In Figures 3 and 4 the bar 4 is of square cross section, but the back surface 33 of each hook 25is not at right angles to the surfaces 31 and 32 thereof, and slopes backwards from the surfaces 31 to the surface 32. The blades 3 are shown in short chain lines in the osition in which they have first engage the contacts 1 and 2, but the bar 4 has not moved forward between the surfaces 31 and 32 of hooks 25 further to compress :the sprin s5, and to press the wedge shaped edges of the blades 3 strongly between the teeth 8 of the fixed contacts 1 and 2. Figure 3 shows also that the grooves 30 slope backwards from the lower to the upper surfaces of bar 4, so that when the switch is closed the springs 5 contact only with the lower edges 34 of the grooves.

lVhen the bar 4 has been rotated around the axis 6 in a clockwise direction as seen in Figure 3, from the fully closed position so.

that bar 4 slides between surfaces 31 and 32 of hooks 25 away from the blades 3 to the position shown in short chain lines, in which the strain onsprings 5 is partially relieved, and is then further rotated to open the switch by moving the blades 3 from the fixed contact 1, the springs 5 acting on the edges 34 of the grooves 30 cause the blades to tend to pivot about the edge 35 of bar 4, with the result that the lowermost edges 36 of the wedge shaped faces of the blades 3 are maintained in contact with the sides of the teeth 8 of the fixed contact 2. Similarly the edges 36 are maintained incontact with the fixed contact 2 whilst the switch is being closed by rotating the blades 3 in a counterclockwise direction about the axis 6. The initial and final movements of bar 4, when the-switch 'is being opened and closed respectively, and the bar slides between the surfaces 31 and 32 of hook 25, cause the blades 3 to slide over the contacts 1 and 2, since the .bar has a component of movement in a direction parallel to the longitudinal axes of the blades, which movement is transmitted to the blades by the bar-4 bearing on the surface 32 or on the surface 31.

Figure 5 shows parts of a switch similar to that of Figure 3 except that the bar 4is shaped as an angle iron suitable for use when 1' -Blades{ai1d springs; inav .atstrong barlis required .for. carrying a rela- I tively 'large. number. of blades. 'In this 'in-' stance for the --.-purpose:of .maintaining'the Y :bladesfi in engagement Iwith thei fixed .con-

pivot about-thepointSB'T of platesQAywhich points --engage the recess 38 of thebar 45., 1 r:TAs;the ;bar'4;rotatesabout tllGfELXiS 6 in a clockwisedirectionas seenrin Figure 5, pres sure between the operative faces of the blades blades 3 leaving; contact 1,: whilst the lowermost"edges 36* oftheblades are maintained -.in contact with the sides ofthe teeth Sof the fixedfcontactzina inannerfsimilar to that alreadydescribed inconnection With Figures 311I1Cl-4, thesprings 5 acting; onthe lowermost V 1 edges-3a of igrooves 30...; Clearly whenbar 4 is rotated in a counterclockwise direction as Y seenziingFigure 5 froin'.:thewopen position,-in

'- or'der to clo'se the switclnxtheblades 3 pivot about/the points37;untilthe operative faces .which; the points 37 disengage the recess 38 was the barf moves forwards in hook 25, and

H the springs 5 are vit'urtherstrained. '1'

-, The individual springs and bladesof Fig-, B

" supportthe strips b-utto allow liinited'movel ures3, 4 and '5 can: readily be removed or replaced without disturbing other parts of the inswitch, :forzif thehead 27 f a spring is drawn backwards outrofengagement with the :recess 28 of, the; corresponding blade the springmay be pulled upwards, thus removingjit from between the plates 24. After "an the spring has been removed the blade may beydisengaged from 'thebar't me'relyby slidging it-backwards', so that the-surface 32 of shookisfree of the'adjacent under surface of the bar a, and-by then lifting the blade.

-,,by converse operations; Y ffiglfthe contacts 1-and=2 andthe bar tare made sutficiently long the jcapacity of the k j switchxmayreadily-be increased by adding more blades: The bar 4- may, for example,

-be' eXteIidedon the outer sides of 'the side fimemb erszi whichsupportsthe bar andon which the bar is pivoted.

The blades?) may be associated with any suitable opening,- and ;;closing mechanism glwhich mayinclude catch 'geaiiforholding the circuit breaker closed. Furthermore, the blade's r'nay be associatedwith auxiliary sp arkingcontacts' of any: suitable kind, whilst 'theivariousparts of the switch may be modified: inmany fdiiierent. ways gfor example, the. springs foractlnggfonthe blades in the typeofswitch shown inF igures 1 and 2 may I *be formed-as plates or strips of steeltapere'd gfr'oin} the ends Where they are secured to a tween the top and bottom contacts, and the rubbing action that occurs on closing and opening the circuit breakers helps t ensu-re close a circuit breaker is small, adequate proity of rigid strips ha ving edges adjacent and readily be replaced blades suchastwo blades. In operation the aforedescribed. circuit breakers are normally prevented from becoming overheated since air circulates freely around the blades, whilst the springs areii'emote from the-operative blade surfaces, so

that should the latter owingto overloadbe- Bxand contacts 1 fan'dq2 iszmaintained, since, :-the springs 5, ar'e' initially s'trained to aprev .determinedextent, until the recess 38 engages f3 5 i 'the;points 37 of platesQhafter Which,,upon

; further rotation ofthe bar, thejswitch opens,

come hot the springs remain relatively. cool and retain their elasticity. The pressure of the springs, moreover, is shared evenly benot only that the contactsurtaces are clean, 1

but that the blades are properlybedded against the fix'ed contacts when the circuit breakers are closed; Moreover, the voltage rlrops across the contacts arefrelativelyj'low,

and although theamount of work required to vision'mayreadily be made against wear ordistortion" of the fixecl rontacts or contact blacless of'blades 3 and contacts 1 and 2 engage, after lclaimz 1. An electric switch comprising a pluralsubstantially parallel toone another and constituting contact surfaces,inea ns arranged to ment of the strips relatively thereto and biassing springs "separate from the strips adapted togtransmit 'pressure through the strips to the said contact surfaces when-the switch is "closed. q 4

'2. An electric switch comprising aphi- "ralit'yof rigid strips having"bevelle'd edges adjacent and substantially*parallel to one another and constituting contact surfaces, means arranged to supportthe strips but to when the switchfis closed. j

3. vAn electric switch comprising a plurality of rigid strips spaced apart from 'one -an-"lla other and having edges adjacent and substantiallyparallel to one another and constituting "contact surfaces,means arranged to support the strips but to allow limited 'movement'of J the strips 'relatively' thereto "and biass'ing lzo fsprings'iseparate from the strips adapted'to act on" edges of the stripsreinotefroni' the said contact surfaces andtotransmitpressure through the, strips'tothe said contact I surfaces whenthe'switch is closed. D j

4. An electric switch comprisinga plurali ty of rigid strips having edges adjacent and substantially parallel to one another and con- :stitutingfcontact surfaces, means arranged to I support the strips but toallow l mited,move-"-1lfl I fluent of "the strips relatively thereto and biassing sprin individually :associated with but separate rom .Ithe vstrips 'andaadapted :to transmit pressurethrougli zthe stripsto the said contact surfaces when the switch .is closed. s

5. .An electric switch comprising a contact 'element,;a supportingmember forsupporting .thecontact element, ahookshaped position- ,part provided on thecontact element-and ae easably engaging with the supporting :member and abarshaped spring which is xiwithdrawableia-ndacts at its ends on .thecon- -:tact element and between its ends on the supporting member, the spring cooperating with the hook shaped positioning part in -;lock.ingthe contact element to the support- ,ingvmember. v

6. .An electric switchcomprising a contact 'elementin the form of a strip havingan edge which constitutes a contact surface, a sup- .portin member for the contact element, a hooks aped positioning partprovided-on the strip remote from the contact surface and iormed witha slot and releasably engaging *w'mh thesupporting member, a bar shaped spring which fits through the said slot and acts at its ends on the contact element and between its ends on the supporting member and means .for longitudinally positioning the spring which is withdrawable and which cooperates "with the hook shaped positioning pantinlocking thercontact-element't-o the supmember. 7 e

7. An electric switch comprising a moving .bridgingcontactelement, a supportmgmembcr or supporting theicontact element, a positioning part provided on the vcontact'ele- {Bent and .tormed with a pivotal edge and cooperating "with the supporting 'member which is'formed with one pivotal edgethat is ineng'a'gement with thepivotal-edge of the ipositioning part duringiopening of the switch 7 and a second pivotal edge further :towards an ,end-ofthebridg' contact element than and .oppositely'dispos dd relatively .to the first 1votal-edge,. d a bar shaped s r ng whic l is strained both when the swito is open and when theswitch is closed and which acts intermediate its ends on the second pivotal edge and at opposite sides of thesa id edge on the contact element,

i 8. An electric switch comprising a moving bridging contact element a supporting memher for supporting the contact element, a positioning part provided on the contact element and formed with a pivotal edge and cooperating with the supporting member which is formed with a pivotal edge that is in engagement with the pivotal edge of the I positioning part during opening of the switch 3nd a'second pivotal edge furthertowards an end of the bridging contact element than =and oppositely disposed relatively to the first pivotal edge, a bar shaped spring whichis blades spaced apart with edges rofthe :adjacent and substantially parallel tozone another, the said edgesbeing bevelled 'imd constituting contact surfaces, a supporting strained both when the :switch is open and 'when'the switch is closed and which acts .in-

'termediate itszends on thesecond pivotal e andiat opposite sides of thegsaid edge on e contact element, and a pivot spaced when the switch closed 'to one side of the supporting member which is adapted to rotate about said pivot.

19. An electric switch comprisin it 'movin bridging contact including a p are its member for supportingthe bridging contact, hook shaped positioning ipazrts provided on the blades and formedisl'ots and with pivotal edges and releasably enga the supporting member which is formed a one pivotal edge that is in engagement with aha pivotal edges of the positioning parts during opening of'the switch'and a second pi v- 'otal edge further towards (an end of the bugsing contact than and-oppositely disposed atively to'the first pivotal edge, a m of bar shaped springs each of which is willidrawable and is strained when the switch is open and is further strained when thesavitch is closed and passes through -.a slot in a positioning part and acts intermediate its ends on the second pivotal edge and atopposite sides ofthe'said edge onablade'uemote from the bevel-led edge thereof :and cooperates with the hook shaped osition'ing part of the blade inloc king'the ladeto timingporting member, means for longitud positioning the springs, and a pivot spaced when the switch is closed to one side of the supporting member which is "adapted to rotate about the said pivot.

10. An electric switch compris' V 5a moving bridging contact including :a lade In edge of which constitutes a contact surface, supporting means arranged to support the blade but 'to allow limited movement of the blade relatively thereto and includingm pivot, and a biassing spring arranged to act on the blade between the ivot and an end of the r limited movement of the blades relatively v thereto and including pivotal means, andbar shaped biassing springs arranged respectively to act on the edges of the blades remote from the said contacttsurfaces between the pivotal means vand an end of the c0ntact,'the springs being strained when the switch is open and further strained when'the' switch is closed and being adepted t0 trans= mit pressure through the blades to the con tact surfaces.

In testimony whereof I aflix my signature.

ARTHUR ERNEST 'ANGOLD.

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