US 2791648 A
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Description (OCR text may contain errors)
May 7, 1957 R. A. MALONEY DRIVE MECHANISM Filed Aug. 9 1951 -4 Sheets-Sheet 1 16) ROBERT A. MALONEY WK w m ENTOR May 7, 1957 Filed Aug. 9 1951 R. A. MALONEY DRIVE MECHANISM 4 Sheets-Sheet 2 INVENTOR ROBERT A. MALONEY R. A. MALONEY' DRIVE MECHANISM May 7, 1957 4 Sheets-Sheet 3 Filed Aug. 9, 1951 INVENTOR ROBERT A.MALONEY 16.0.4441 a ZM J May 7, 1957 R. A. MALONEY 2,791,648
DRIVE MECHANISM Filed Aug. 9, 1951 4 Sheets-Sheet 4 J g. I 11 .5.
33 INVENTOR ROBERT A. MALONEY United States Patent 2,791,648 DRIVE MECHANISM Robert A. Maloney, Canousburg, Pa., assignor, by mesne assignments, to McGraw-Edison Company, a corporation of Delaware Application August 9, 1951, Serial No. 241,145 26 Claims. (Cl. 200-18) This invention relates to a new kind of drive mechanism which is relatively silent and cushioned in operation and in which fewer principal or massive parts are accelerated or moved at a higher speed. In particular, this invention pertains to a novel drive mechanism suitable for switch gear such as those used in load ratio control or step voltage regulator equipment.
A variety of electrical equipment is used to maintain voltage of the load in electrical systems. A number of these devices include tap changing under load and many, particularly those having lower rating, are frequently fully automatic and employ high-speed switching between the respective contacts or transformer taps in the circuit. Further, in the lower ratings, the switching equipment may also perform the current interrupting service. In order to obtain relatively high-speed tap changing in such circuits, many prior drive mechanisms heretofore used, employed springs for snap action and in this employment many of the principal or massive parts of the drive had to move at high speed in the course of the snap action portion of the cycle with attendant noise and shock. The ditficulty was increased when the device was substantially moving at its greatest speed near the end of its travel. Such drives therefore frequently required relatively expensive alloys for construction and greater power for equivalent average speed of operation. Such tap changer drives were also used with equipment having higher kv.-a. and current ratings although at such higher ratings the use of separate circuit breakers for current interruption in the circuit is more common. Many of these devices have reversing gear by means of which the same winding can be employed both in opposing and in augmenting the line voltage under control, whether single phase or polyphase voltage control.
In this invention, a new kind of drive mechanism for voltage control switch gear is provided which overcomes the foregoing difliculties of prior devices. In the new construction of this invention, a snap action is obtained with relatively low speed operation of many principal or massive parts. The result is far quieter operation, less strain on the equipment, longer life and improved performance. Control of the speed-time action is obtainable with a device made under this invention with relatively more rapid breaking of the are and less rapid speed near the end of the travel of the device. Further, in this new construction cushioning means are provided as well as a symmetry of structure which markedly minimizes any tendency to dynamic imbalance. A reversing arrangement may be included which is positive in operation and provides for opposition or augmentation of the supply voltage.
Other objects and advantages of this invention will be apparent from the following description and from the drawings, which are illustrative only, in which:
Figure 1 is an end view of one embodiment of the new drive mechanism of this invention with a portion thereof broken away;
Figure 2 is a view taken generally along line 11-11 of Figure 1 with, in addition, a schematic showing in section of a tap changing and reversing switch gear arrangement;
Figure 3 is a view on a somewhat reduced scale of the last-mentioned addition only taken along line III-III of Figure 2;
Figure 4 is a view on a somewhat reduced scale taken along line IV-IV of Figure 2 with the intermittentmotion gear at rest;
Figure 5 is a view similar to Figure 4 as the intermittent-motion gear is being moved and is passing through its reference position from the position shown in Figure Figure 6 is a view similar to Figure 4 after the intermittent-motion gear has been still further moved from the position shown in Figures 4 and 5 and has come again to rest;
Figure 7 is a view in elevation of the other side of the intermittent-motion gear in the reference position shown in Figure 5 showing a reversing arrangement;
Figure 8 is a view similar to that shown in Figure 7 with the intermittent-motion gear in the position shown in Figure 6;
Figure 9 is an end view of the threaded coupling shown in Figure 2 and its arm taken along line IX-IX of Figure 2;
Figure 10 is a side view of the threaded coupling and arm shown in Figure 9; and
Figure 11 is a view partly in section of a modified spring retainer mechanism.
Referring to the drawings, a plate 10 of metal may be bent into the form of an angle to serve as a supporting shelf for the new drive mechanism of this invention. If, for example, the new drive mechanism is to be used inside the tank of a power transformer, plate 10 may be supported on and bolted to angles 11 forming a structural portion of the interior of the transformer tank. Angle pieces 12 may also be provided at the upper edge of plate 10 to complete the supporting attachment of the new mechanism to the structure with which it is to be used. Side plates 13 are welded to plate 10 and brackets 14 in turn are welded to plates 13. A rigid bar 15 extends between the brackets 14 and is bolted thereto. Pads 16 are welded to the bottom of plate 10 on the inside of the angle.
A conventional prime mover 17 may be bolted to the pads 16 and thus afiixed to plate 10. Prime mover 17 may comprise a reversible electric motor 18 firmly mounted on and fastened to a casting 19 within which there is provided a conventional gear reducing mechanism 20. The prime mover 17 is enclosed in such a manner that it may be submerged in the dielectric liquid, such as transformer oil, if the new mechanism of this invention is used in a liquid-type transformer. A short shaft 21 extends from the casing of gear reducer 20. A hand crank may be used to turn shaft 21 and thereby operate as a prime mover to cause the new drive mechanism of this invention to function. Ordinarily, the new mechanism will be operated electrically by means of any of the many circuits available for tap changers in the load ratio control field. Such circuits, which need not be illustrated here, may be so arranged as to be fully automatic or manual in the sense that push buttons are used, for example, to control the electrical circuit to which the new drive mechanism is connected through leads 22 of motor 18. In addition, such an electrical control circuit whether automatic, semi-automatic or manual or a combination of these may include limit switches or mechanical steps or both to limit the angular rotation in either direction of the mechanism with which the new drive of this invention is used.
A conventional tap changer for step voltage regulation,
ta cts extend, for example, through panel 23 and haveleads connected thereto on the other side thereof. An annularly spaced pair of movable contactslo may coact withthefixed contacts 24. inboth symmetrical and bridging positions to effect step voltage regulation as the movable contacts 26 are moved by a contact shaft- 27 whic thev e ou t d; Each ip ing 2,3: audits ush 2 ake a n epen n e ectrical conneetiemwnh.
its'r espective movable contact 26.
In one form of tap, changing apparatus when both 195131 ?On l6= n conta wi h fix d onta t Zea. l or 1letl ymm t alpo ition he apparatu is, regarded as being in its single electrical neutral position. It is at that time. that movable contact, 34 is rotated into contact with the other. of the fixed contacts 25 sothat no current is interrupted and at the same timethe regulation transformer windings are reversed in the circuit so asto prepare it for a contrary regulatronactron.
That is if the tap changer had been moving to boost line voltage, the actionresulting from throwing movable con tact 30 to the otherfixed co'ntact ZS Would,,for the. same direction of movement of the equipment, buck the line voltagethereafter, and vice versa Movable. switchcontact Silis carried on an auxiliary contact shaft 31. Both shafts ZZ and 31 may be connected. by flexible couplings 32a and 32b respectively to coupling shaftsZT/a and 31a respectively.
To return to the new drivermechanism, an-output shaft 33 from gear reducer 241 extends toward plate 10. A bearing 34, properly bushed, supports the. other, end of shaft 33. asit is turnedineither direction under the influence of motor 18 or under the influence of ahand crank turning shaft 21. Asleeve 35 whi ch maybe a casting orfor ged metal shapefitsover shaft33- and is keyed thereto, "lhe sleeVeElS Comprises a cam 36 at-the end and .a pinion 37, at the other. Although as. shown these parts are integral, they may be separately made and keyed to theshaft 33. Cam36 is .ofi a,drum type and is provided with a rise portion 36a and afallpoition 36b,
by means of theexte nt of the respective peripheral portions of which a suitable timing "sequence of the new drive mechanisrnis obtained, The ahgnlarposition of cam 36 on shaft 33" is symmetrical relativeto the angular position of apin 38'whenthe-action of the .new,mecha nism is reversible, as .may norr11al1y ,b.e-the. case.
Pinion 3'73comprises tw. o spaced integral annular flanges 37a and 37b; The pin 33 connects thetwo fianges atv the Z appropriate, angular. position corresponding; to, the angular setting on shaft 33fof cam-36, andofthe respective positions of the electrical contacts in the tap changer. previously described. A roller 39.is ,rotatably mounted on pin 38; for engagement with the sides of recesses 40,
extending radially and in spacedrelation around the periphery of an intermittent-motion rotary plate or gear 41 which may be of theGeneva type. Teeth 42cf gear 4ll=between therecesses Aware provided at their. crests with depressed portions. 43j of concave arcuatenature whichmay be termed saddles. A hub 44 ...ofpinion57 which is integraltherewithis shown-incross. section in Figures-4 to 6" and provides meansfor locking gear infest position between operatiye engagements of-roller 39 and'the side of any tooth 42 of gear', 41, as illustrated;
Suitable. washersmay by a roller 47. Roller 47 in turn is rotatably mounted on the rear side of gear 41. The lower side of arm 45 is provided with an arcuate 5101243 to provide a lost motion action between arm 45 and a pin 49 on a throw lever 50. When assembled, pin 49 extends into opening 48 at all times. An integral journal 51 is provided on lever 50 and is rotatably supported in a bearing 52 in plate It the said bearing being, suitably hushed.
A sleeve 53 is keyed to the rear end of journal 51. In turn, the. forward end of: coupling; shaft: 31a is connected to sleeve 53. for rotation. Thereby; movement of throw lever 50 to one side or the other will move movable contact'30 of thereversing switch arrangemcntifrom one fixed contact 25 to the other but movable contact 39 will not stop between. the contacts 25 becauseof the lost mo tion characteristic of the arcuate slot 48 even though gear 41 is in its reference position as shown in Figure 5. In that; reference,- position, roller 47 hasentered slot 4% bringing locking-pins 54 into horizontal alignment and continuation of the movement of gear in the same-direction. will; rock: arm. 4-5 into the position, shown in Figure 8. to effect, through pin 49, a throw over of movable, contact 30 to the. other fixed contact 25. The reference position shown in Figures 5 and 7 is located aboutrnidway; of. the reference positionmovement sector defined-by the radii. hisecting the saddles 43; immediately on each; side of the roller 47. In the; illustrated embodimenhgear. 41. is provided witheighteen teeth 42. and isintended to be;capable of substantially two fullrevoluw tionsin either. direction between its limits of rotational movement. In; addition,- there-are 9 fixed contacts 24 for aboutsixteen steps-in either direction since the contactslfi; are; operative both iii-symmetrical position on a single. contactldpther;thancontact 24a and in abridging position bridging two. contacts- 24. The direction; of movement. of. contacts .26,will correspond, to the direction of, movement of the gear 41; The reference position movement, sector. in turn. occurs, about halfway through thesubstantially twofullrevolutions of gear 41 which may be provid-ed in .eitherone direction between its usual limits ofmovement for theillustratedembodiment. ln generaLthenew. mechanism will be. so assembled that thfe switching ofnn'ovable contact 3%) from the fixed-contact 2 5 onwhieh it is, resting to the other fixed contact. 25 will tale-e place. during. movement; of the gear: lr thr hjheareference position movementsector and will substantially becompletedbefore either movahlecontact 2 6,' as .th e. case maybe, leaves fixed contact 24a;
As shown in ,Eigures 7 and 8, an inner annular locking afisfiii tld m t rl ev 56e JPI'OVldQdlOH the rear side of 41. Flange Sdisprovidedwith there: sp ective openings 57 and .58 .toper-mit alternateentry and exrtmpyemeng'as the casemay be,- betweenthe two flangegfor the right-hand and-left-nand locking-pins 5 as gear dl swingsithrough its reference-position intone orthe other. The, positioningof-the locking pins .may: ble made such. that no inner fiange SS is re quired. Thehtraek made bythe locking flanges insures that norotationofarmAS .on-shaft 33-may take place except as gear4l rotatessubstantially entirelythrough its. referencaposition;inone directionor the other, thatis, substantially -from-its attest position on oneside-of the referenceposition tojtsatrest positionton theother side. of the refqrencfirpositie Reversalof movement of gear 41 when not in ,its referenceposition 'movement-sector does not change the-angnlanposition of arm 45-relative. to th'qaxisofshaft. 33,0f.the. locking pins,54 one of which is inside flange 56.
A switch shaftSfiis rotatably supported inabearing 60in bar 15,an d in ;a,bearing. 61 .inplate .llhwhich bearings are respectively suitably bushedrand provided with a needle bearing... Atsleeve62tis keyed to-the rear endiof switch. shaft 1 5.9 preventing, any V forward axial movement of the shaft 59. In addition, coupling shaft 27:: isalso suitably connegted for rotation ;to,. sleeve 62.:v Theforma mas ward end ofrswitchsshaft 59Vis threaded for engagement by a.-nut-.63 which backs .up-athrust bear-ingu64. 'Thrust bearing 64 in turn bears against the closed zendtofthe femaleportionofiofaa threaded coupling. ASShOWH in Figure 2 the closed end .of coupling 65'bears,against a'Washer-66 which in turn is positionedaby ashoulder 67 on :shaft 59. -Hence,tl1e femaleportion 65 of thethreaded coupling is axially immovable relative to shaft59 but may -be:rotated relative thereto. A'disc member ;68-is jourtnaled ton-shaft59 and hasan integral.forwardly extend- ,inghub- 69 the-exterior ofwhiehzishelically threaded in ;.pitch and dimension corresponding to the threading of .theifemale portion 65. Disc member-68 maybe moved .raxiallyovershaft 59 but eannotbe.rotated'relative to the-axis of shaft 59 although shaft '59 ean-rotaterelative to member 68. Thus portions65 and 69 make-an-entire -threaded coupling.
'Adownwardly and rearwardlyextending lever arm 70 is integral with couplingportion 65. .-A modified clevis -71 at the lowerend of arm 70 has an opening 71a therein which surrounds rod 72. The diameterofopening 71a is sufiicient to permit arcuate-movement of arm '70 rela- .tive to red 72. Registering :slots 73 :in thersides 'of theclevis, which are of sufficientlength to permit the arcuate movement of arm 70, engage the-ends-of a pin 74 which extend'thereinto. Pin 74 passesthrough and isafhxed to followerrod 72 .at thatposition 'along the length of rod 72 at which a proper location of the axial movement of hub 69 along shaft 59 -is.obtained. Follower rod -72 is axially movable ina-bracket'75 which is bolted tobar .15. Properlybushed registering openings in .the sides 76 of. bracket 75 enable movementflofrfollower rod 72 to take place along its own axisand generally radially relative to cam 36. A spring 77 presses arm 70 .downwardly, that. is inrclockwise directionas viewed'in Fig- .urevl, until and unless arm 70 is moved ina counter- .cloclcwisedirection byengagement of:cam.rise .36aand a roller 78 fastened to the lowerrend .of rod'72.
.in .the embodiment shown in the drawings, the hub 69 is provided with a left-hand thread. Therefore, vcounterclockwise movement ofarm 70 as viewedinvFig- ,ure 1 will shift disc .68 axially along switch shaft;59 toward the front, that is, toward nut 63. On .the other hand, movement of arm 7 inia .clockwisedirection .tends to separate the parts (SS-69 .ofthe threaded coupling and move disc 68 toward bar for a purpose which will be described. Suchmovement in a counterclockwise direction of arm 76 as viewed in Figure 1 willvtake place when the roller 78 is engaged by cam rise 36a. 'When the rollerifi leaves cam rise 36a, spring'77 will returnarm 70 to'its original position as shown in Figure 1. Thus, .the axial movement of disc 68 in either direction-alongshaft 59 will be positive and will minimize any tendency of the parts of a clutch 7910 stick.
Clutch '79 comprises a frusto-conical male portion 36 which maybe designated the 'drivenorrholding part and female portion 81 whichmayibe designated the .drivingpart. Clutch portion '80 is inthe general'form of an annulus which is provided with a bushing 82 which is'freely slidable and rotatable on switch shaft 59. A clutch plate 855 has afiixed to it a pair of discs 84 of frictional material the conical peripheries of which form the engagingsurface thereof. Sleeve bolts '85 slidably extend'through bar 15, proper bushings againibeingprovided, and are screwed into plate '83. Sleeve bolts 85 also'serve as guides for springs 86 extending between the front of bar .ifi'and'the rear of disc 68. llBolts'f87 hold the forward end of the sleeve bolts 85 tightly against disc 63' around the axis thereof. Thus, springs '86 normally urgehold portion '80 away from engagement with clutch part 81 to disconnect the two parts. In some embodiments the springs 86 will not .be necessary and reliance for disconnection may be placed entirelyronthe action of coupling 65-69. The influence of spring 77, which is powerfulthan the total force of springs =86, acts to .connect the two parts v,-81 andrthereby holds part-.81..and shaft 59 immovable in .the manner of a .brakewheneverrod 72. isnnot in engagement with cam rise.. 36a. However, when arm 70 is lifted by cam rise :36a'thencoupling 65-69 tends to foreshorten and since portion 65 cannot move axially along shaft 59, disc 68 moves=forwa-rdly forcing clutch portion 80 out of connective engagement with clutchportion '81 freeing the latter for a snap action. driving movement of shaft 59.
Driving .portion 81 is the female part of the clutch 79 and has an.interior:frusto-conical surface 88 adapted .to engage the\discs 84 when. plate 83 is moved rearwardly along switch shaft 59. Member 81 ispart of a casting orforged metalshape 89 which is immovably keyed to switch shaftx59. .lnaddition, an integralcircumferential flange 96 on switch shaft'59 fits into a corresponding recess. in sleeve 89 and is there held .by thrust cap 91. Therearportion of;sleeve 89 is provided with a circumferential gro.ove.92. .Symmetrically arranged around the axis of switch shaft 59, thesides of the groove 92 normal to-the said axis are provided with opposed registering .pairsaof generally radial slots 93 extending to the outer edges .ofthe. groove-92. Each pair of slots 93 engages :the trunnions 941of -a spring retainer'95 respectively. In elevation these spring holders 95, as shown in Figures '4 to 6, for ;example,. generallyform a polygonal figure. .Extendingthrough each retainer 95 from end to end thereof there is a rod 96 positioned somewhat in the "manner .of a chord relative to gear '41. The ends of eachirod 96-fitinto corresponding recesses in corner posts :97. Corner-postst97 in turniare'fastened by bolts 98 ,torthe frontsideofthe gear 41. The gear 41 is rotat-ably supported TOHFSWiiCh shaft 59, a needle bearing'99, for example, being interposed .therebetween. A washer I 7160;maypbeipositioned.between the hub of gear 41 and the .front .end of-bearing161.
when-thesnew mechanism .of this invention is at rest .or ;gear41 is:momentarilyin-its dwell periodit may be in a position suehvas thatgenerally-shown in Figure 1. In that position hub-44 is in locking engagementwith a saddle 43-Of-21-f00ih542 and theroller Idextendstoward cam-portion 3611- under the influence'of spring 77. Arm 70-therefore is in'itslowermost position and clutch parts 80-81-are connected holding switch shaft 59 against turning.
'slf an impulsezfrom the voltage regulating control circuit 'is-received:causingmotor 18,'for example, to turn in one direction *orthe :otheryorif'such impulse is continuing, the shaft 33 will rotate and if continued'for a sufiicient length .of time, the roller 39 will engage that recess 4i; 'towar'd whichit is-approaching. Continued movement in 'thesame direction of shaft 33 will turn gear 41 in the oppositedirection to the direction'of' movement of shaft 33 through 'one succeeding movement sector after the other until shaft 33 stops turning or is reversed in movementeausing'a reversal of movement of the gear 41. For each full 'revolution of shaft '33 the tooth 42 immediately above the shaft will be moved through a movement sector angle defined by the radii bisecting the saddle 43 of the tooth 42 immediately above-shaft 33 and the saddle 43 of the adjoining tooth-42 moving toward shaft'33. Preferably adjacent the end of that movement sector, roller '78 will-be engaged'by cam rise 36a'raisiug arm 70 and disconnecting partsSii and S1 of clutch 79 to permit sleeve 89-to snap the movable contacts 26 to the next contact position. Meanwhilehub 4d will become engaged in loci:- ing relation-with saddle 43 of the said adjoining tooth 42 which is now over shaft '33. "Clutch'79 will remain .disconnected until roiler 78 againcornes opposite the cam fall portion 36b. in ordinary'operation, voltage regulation will involve one ormore steps in one direction interspersed withone or more steps'in the'opposite direction depending upon the conditionsin .the circuit being controlled.
As ,gear 41 is moved, for example, from the .position shown in Figure 4 to the position shown in Figure 6, that is, through a sector of movement, thereby loading the spring retainers 95 to complete by snap action a single step in the movement of contacts 26 relative to contacts 24, the rods 96 compress the springs 101. The rods 96 are provided with shouldered portions 102 adjacent the extremities of each thereof. Hence, as the rods move under the influence of the movement of gear 41, that shoulder 102a facing in the direction of such movement as illustrated in Figures 5 and 6 passes through an opening 103 in the adjacent end of the spring holder or box 95. As a shoulder portion 102 enters retainer 95 the shoulder 102a will abut a piston 104 interposed between that shoulder and spring 101, thereby compressing spring 101. A similar piston 104 slidable in box 95 is interposed between the other end of spring 101 and the other end of the box 95 for corresponding action in the other direction when gear 41 is turned in the other direction. During the turning of gear 41 or at least during the initial stages of that turning, the clutch 80-81 prevents any rotation of hub 89 and the trunnions 94 are held immovable except for such pivoting and sliding of them as takes place in slots 93 during the movement of the respective rods 96 through bOXes 95. When follower rod 72 moves away from the axis of shaft 33 upon reaching cam rise 36a, the threadedcoupling 6569 will disconnect portions 80 and 81 of the clutch 79. The springs 86 also act to disconnect clutch 79. Immediately, the springs 101, compressed as shown in Figure 6, will release their energy and through trunnions 94 of spring holders 95 will snap hub 89 and thereby rotate switch shaft 59 through the same movement sector angle with a corresponding snap, without any of the parts associated with shaft 33 or gear 41 being correspondingly moved in any such snap action. The snap action rotation of switch shaft 59 in turn, as aforesaid, will through shafts 27 and 27a and their respective insulating coupling 32a move the movable contacts 26 to the next contact position at high speed thereby minimizing arcing and interruption of current. In the event that the prime mover 18 should stop in the course of a movement sector before clutch 79 is disconnected, the springs 101 will return gear 41 to its original position before the step began to await a further actuation in one direction of the other. Seal-in switches may be used in the electrical circuit of the new drive mechanism to insure against any suspension of a voltage regulation step after it has once begun and proceeded through some predetermined portion of the movement sector angle corresponding to such a step.
The symmetrical arrangement of the rods 96 and the spring retainers 95 about the axis of switch shaft 59, gear 41 and hub 39 insures against troublesome stresses or dynamic imbalance in the operation of the new device. In addition, adjacent each end of each spring box 95 and spaced therefrom there are provided openings 105. These openings in connection with whichever piston 104 in each retainer 95 is being moved, at the time being, regulate the time-travel characteristic of the operation.
In the new drive mechanism each spring 101 preferably will be precompressed or preloaded and will fill its entire box 95 when in an at rest or dwell position as shown in Figure 4. fter the springs are compressed as illustrated in Figure 6, the disconnection of parts 80 and 81 of clutch 79 to permit the snap action will cause the depressed piston 104 in each retainer 95 to snap back, relatively speaking, toward the adjacent end of the retainer 95. Once the respective piston 104 in so returning passes the openings 105 there will be a deceleration during the remainder of the travel of the respective spring boxes 95 thereby cushioning the snap action and preventing shock to the parts so snapped. In such snapping, the hub 89 and hence the switch shaft 59 catch up with the gear 41. If there is any tendency of the spring boxes 95 to overrun, that tendency will be substantially completely prevented by the preloaded springs 101. In other words, when the springs 101 regain their original length as shown in Figure 4, renewed or continued movement of a prime mover is required to begin a new compression of the springs 101.
A conventional operation counter switch 106 having a contact arm 107 may be mounted on bar 15 so that arm 107 engages the exterior periphery of clutch part 81. That exterior periphery may be provided with a number of lands 108 equal in number to the number of teeth 42 on gear 41. Hence, each time oblique-surfaced coupling --69 passes through a holding and release cycle relative to the two parts of clutch 79 for each step or movement sector, Geneva gear 41 will have moved an angular distance of one tooth 42, and hub 89 and therefore lands 108 will have been snapped a distance of one land, thereby operating switch 106 once to enable it to cumulate the number of tap changes made.
A spring and spring retainer subassembly is illustrated in Figure 11. in this subassembly a spring rod 96 is immovably mounted by its ends in corner posts 97 fastened to an intermittent-motion gear like gear 41. A spring 101', preferably precompressed or preloaded, surrounds rod 96 between the enlarged end shoulder portions 102 of rod 96. Spring retainer box surrounds the spring 101 and annular end wall members 109 fit into corresponding recesses in each end of each spring box 95'. Annular upstanding edges 110 of spring boxes 95' are crimped inwardly over the end wall members 109 to hold them firmly in place. One or more openings extend through spring boxes 95 a predetermined distance inwardly from each end. The size and number of these openings 105, like the openings 105, will determine in part the speed-time snap action characteristics of the new mechanism. An opening 111 extends axially through each member 109 between the outer side of the ends of spring box 95' and the outer face of respective pistons 104 adjacent thereto. Each piston 104' is provided with a hollow differential hub the outer portion 112 of which closely surrounds shoulder 102 and the inner portion 113 of which closely surrounds the narrower diameter of rod 96' on the other side of the body of piston 104'. One or more openings 114 extend through the body of piston 104' from the inner face thereof to the interior of the aforesaid hollow hub. Shoulder 102a abuts a corresponding opposed shoulder on the inside of the hollow hub of piston 104 at the plane separating the two portions 112 and 113.
The operation of the subassembly is similar to the operation as illustrated in Figures 4 to 6. Thus, if we assume that the left-hand corner post 97 under an actuating irnpulse is rotated to the right, spring retainer 95 in that portion of the step being held against rotation, the left-hand shoulder 102a as viewed in Figure 11 will move the lefthand piston 104' to the right shortening spring 101. If the subassembly is immersed in transformer oil, for example, such oil will move inside the spring retainer 95 between the inside of left-hand member 109 and the outer face of left-hand piston 104 through opening 111. The movement of piston 104 will continue until the body thereof moves inwardly past the opening or openings 105 at the left-hand end of spring retainer 105, and right-hand piston 104 will slide inwardly relative to rod 96.
When the clutch corresponding to clutch 79 is disconnected, the spring 101 will snap the right-hand piston 104' and thereby spring retainer 95' to the right as viewed in Figure 11 since right-hand piston 104' abuts against right-hand member 109. The interior shoulder of righthand piston 104' will snap toward the right-hand shoulder 102a and any oil that may have accumulated between rod 96' and right-hand piston 104' will be vented through the openings 114 therein.
As spring box 95 snaps to the right, the left-hand piston 104 will move to the left in a relative sense and the accelerating force will pass its maximum as when the lefthand piston 104 goes past the left-hand opening or openings 105. Thereafter the relative approach between left- 9 hand piston I04 and left-hand member 109 will-be principally governed by the diameter and length of the opening 111 until the parts are again in equilibrium at the end of the snap action. Movement of the parts in the other direction will operate in the same manner but in reverse.
Hence, in the snap action of the new drive mechanism of this invention, the parts thereof that are moved in the course of the snap action received their maximum acceleration in the forepart or in an intermediate part of their travel and at the end of their travel they are moving relatively more slowly. Thereby, a cushioning effect is achieved and substantially less shock results to the parts undergoing the snap action. At the same time, the greater speed in the earlier portion of the snap action results in breaking of the are as the contacts separate with lessened opportunity for pitting caused by the arc.
Various modifications may be made in the number, shape and size of the parts and in other details of the new drive mechanism of this invention without departing from the spirit thereof or the scope of the appended claims.
1. In a drive mechanism, in combination, a prime mover, an intermittent-motion gear driven by said prime mover, a switch shaft continually connected operatively to a movable contact member, means providing a constant resilient connection between said gear and said shaft, movable means for holding said shaft substantially immovable during at least a portion of the movement of said gear by said prime mover, and means controlled by said prime mover for releasing said shaft to permit it to catch up with said gear under the force of said first-mentioned means.
2. in a drive mechanism, in combination, a reversible prime mover responsive to a change in electrical condi tions or the like, an intermittent-motion gear operatively connected to said prime mover, a holding device having a driving member and a holding member movable relative to said driving member to permit engagement and disengagement thereof, a switch shaft continually connected operatively to a contact shaft, said switch shaft further being connected to said driving member for rotation therewith, means providing a continuous resilient connection between said gear and said driving member, means for connecting said holding member to said driving member during at least a portion of the movement of said gear, and means for moving said holding member to disconnect it from said driving member.
3. In a drive mechanism, in combination, an electric motor responsive to a change in voltage or the like, an intermittent-motion gear operatively connected to said motor, a holding device having a driving member and a holding member movable axially relative to each other to permit engagement and disengagement thereof, said holding member holding said driving member immovable when in engagement therewith, a switch shaft continually connected operatively to a contact shaft, said switch shaft further being rigidly connected to said driving member, resilient means connecting said gear and said driving n1ember, means urging said members into engagement to hold said driving member immovable during at least a portion of the movement of said gear, and means for moving said members axially away from each other.
4. In a drive mechanism, in combination, a prime mover responsive to a change in electrical conditions or the like, a rotatable intermittent-motion member operatively connected to said prime mover, a switch shaft coaxial with said member and continually connected operatively to a movable contact member, a rod connected to said member and disposed away from the axis thereof, a spring adjacent said rod in the path of movement thereof, a retainer for said spring pivotally connected to said shaft, said retainer operatively engaging both ends of said spring and coacting with said rod to compress said spring when said member is rotated and to provide a continuous resilient connection between said member and said shaft, and
means to hold said shaft against movement during at least a portion of the movement of said member.
5. In a drive mechanism, in combination, an electric motor responsive to a change in voltage or the like, an intermittent-motion gear operatively connected to said motor, a brake having a driving member and a holding member, a switch shaft connected to said driving member for rotation therewith, a movable contact member continually connected operatively to said switch shaft, said switch shaft being coaxial with said gear, means rigidly connected to said gear, a spring engaging said means, a retainer engaging said spring, said retainer being pivotally connected to said driving member, means for connecting said holding member to said driving member to hold the latter immovable during at least a portion of the movement of said gear, and means for disconnecting said mem bars to cause said spring to turn said switch shaft.
6. In a drive mechanism, in combination, a prime mover responsive to a change in electrical conditions or the like, a rotatable intermittent-motion gear operatively connected to said prime mover, a switch shaft coaxial with said gear, a movable contact member continually connected operatively to said switch shaft, a plurality of rods mounted on said gear substantially in the form of a polygon, said rods being generally equidistant from the axis of said shaft and symmetrically arranged about the axis thereof, a spring on said rods respectively, a retainer extending between the respective ends of each spring, said retainers being pivotally connected to said shaft, said rods carrying means to engage said springs and coacting with said retainers to compress said springs when said gear is rotated and to provide a continuous resilient connection between said gear and said shaft, and means for holding said shaft against movement during at least a portion of the movement of said gear to cause the com pression of said springs.
7. In a drive mechanism, in combination, an electric motor responsive to changes in voltage or the like, a rotatable member operatively connected to said motor, a switch shaft, a compressing member connected to said rotatable member, a box pivotally connected to said shaft, a spring in said box, a piston slidable in said box, said piston being interposed between said compressing member and said spring, means for holding said shaft against movement during at least a portion of the movement of said rotatable member compressing said spring, and means for releasing said shaft when said spring has been compressed to make said shaft catch up with said member, the movement of said piston within said box controlling the rotatational velocity of said switch shaft during at least a portion of the movement of said switch shaft.
8. In a drive mechanism, in combination, an electric motor responsive to changes in voltage or the like, a driving gear operatively connected to said motor, a driven gear engaged by said driving gear, said gears having different axes, a switch shaft coaxial with said driven gear, a compressing member connected to said driven gear in the manner of a chord, a spring holder connected by trunnions to said shaft, a spring between said member and said holder, means coaxial with said driven gear to hold said shaft against movement during at least a portion of the movement of said driven gear, and means coaxial with and actuated by said motor for controlling the operation of said last-mentioned means.
9. In a drive mechanism, in combination, an electrical motor responsive to changes in voltage or the like, an intermittent-motion gear operatively connected to said motor, a holding device having a driving portion and a holding portion movable relative to each other to permit engagement and disengagement thereof, said holding portion holding said driving portion against movement when in engagement therewith, a switch shaft keyed to said driving portion, a movable contact continually connected operatively to said switch shaft, means resiliently connecting said gear and said driving portion, means urging said holding portion into engagement with said driving portion, said last-named means including a coupling having complementary threadably engageable parts adapted when rotated relative to each other to disengage said holding portion from said driving portion, and means for rotating said parts relative to one another after a portion at least of a single movement step of said gear has been made.
10. In a drive mechanism, in combination, an electric motor responsive to a change in voltage or the like, a cam connected to said motor, an intermittent-motion gear operatively connected to said motor, a brake having a drive member and a hold member movable axially relative to each other to permit engagement and disengagement thereof, a switch shaft connected to said drive member for rotation therewith, means rigidly connected to said gear, a spring engaging said means, a retainer for said spring, one portion of a pivotal bearing rigidly connected to said retainer and engaging another portion of said bearing in said drive member, and means normally holding said hold member in engagement with said drive member, said last-named means including an oblique-surfaced coupling actuated by said cam to move said hold member axially out of engagement with said drive member.
11; ln a drive mechanism, in combination, an electric motor responsive to a change in voltage or the like, at Geneva gear driven by said motor, a brake having a drive portion and a hold portion, a switch shaft connected to said drive portion for rotation therewith, means symmetrically arranged on one side of said gear, a resilient member connected between said means and said drive portion, means to hold said hold portion against said drive portion of said brake during at least part of the movement of said gear, means for disconnecting said portions to permit said switch shaft to catch up with said gear, a rocking sector arm engaging said gear on the other side thereof, a flange on said other side to lock said arm in position until said gear passes through its reference position, and a throw lever engaging said arm.
12. in a drive mechanism, in combination, a prime mover, a rotary plate, a spring, a spring box, means for holding said spring box against rotation about the axis of said plate, means on said plate engaging said spring, said spring box having an opening adjacent to and spaced from at least one end thereof, a piston slidable in said spring box adjacent that end thereof, said piston engaging said spring, and means for releasing said first-mentioned means after said spring has been at least partly compressed by the rotation of said plate, whereby when said spring box is released the "snap action thereof will attain its maximum speed prior to the end of its travel.
13. In a high speed, snap action switch mechanism, in combination, a reversible prime mover, a switch shaft, a plurality of stationary electrical contacts arranged in a circular path, a movable contact member continually connected operatively to said shaft and arranged for sequential engagement with said stationary contacts, a rotatable member engaging said prime mover, means resiliently connecting said rotatable member and said shaft, means for holding said shaft substantially immovable during at least a portion of the movement of said member by said prime mover, said resilient means including energy-absorbing means for retarding the speed of movement of said movable contact member as it moves out of engagement with one of said stationary contacts and in a direct path into engagement with an adjacent stationary contact.
14. In a drive mechanism, in combination, a reversible prime mover, a switch shaft, a plurality of stationary contacts arranged in a circular path, a movable contact member continually connected operatively to said shaft and arranged for sequential engagement with said stationary contacts, and snap acting energy storage means including a lost motion mechanism between said prime mover and said shaft for driving said shaft, means for holding said shaft substantially immovable during at least a portion of the movement of said lost motion mechanism by said prime mover, means actuated by said prime mover for releasing said shaft, and an energy-absorbing device including a piston movable in a fluid-filled cylinder for controlling the rate of movement of said movable contact member during at least a portion of its travel between said stationary contacts.
15. In a drive mechanism, in combination, a reversible prime mover, a plurality of stationary contacts arranged in a circular path, a movable contact member arranged for sequential engagement with said stationary contacts, Geneva gear, intermittent-motion, energy storage means ccnnecting said prime mover and said movable contact member including a rotatable driving member operatively connected to said prime mover, a driven member coaxial with said driving member and operatively connected to said movable contact member, resilient means continually connecting said driving member and said driven member including a plurality of springs disposed symmetrically about the common axis of said members, and means for frictionally holding said driven member substantially immovable during at least a portion of the movement of said driving member by said prime mover.
16. In a drive mechanism, in combination, a reversible prime mover, a switch shaft, a plurality of stationary contacts arranged in a circular path, a movable contact member continually connected operatively to said shaft and arranged for sequential engagement with said stationary contacts, snap acting energy storage means connecting said shaft and said prime mover for driving said shaft including an intermittent-motion gear operatively connected to said prime mover, means for frictionally holding said shaft substantially immovable during at least a portion of the movement of said intermittent-motion gear by said prime mover, and means for locking said intermittent-motion gear in its position of rest.
17. In a drive mechanism, in combination, a prime mover, a rotatable member operatively connected to said prime mover, a driven member coaxial with said rotatable member, a movable contact operatively connected to said driven member, at least three resilient means continually connecting said rotatable member and said driven member, each of said resilient means including an accelerating spring, said springs being disposed symmetrically about the common axis of said members, and means to hold said driven member substantially immovable during at least a portion of the movement of said rotatable member by said prime mover, all of said accelerating springs being loaded in the same sense when said rotatable member is rotated relative to said driven member.
18. In a drive mechanism, in combination, a reversible prime mover, a plurality of stationary contacts disposed in a circular path, a rotatable contact member arranged to sequentially engage said stationary contacts, energy storing and releasing means between said prime mover and said contact member for driving said contact member, said means including a reversible intermittent-motion gear resiliently connected to said contact member, said intermittent-motion gear having a reference position and being rotatable in both directions from said reference position, a reversing switch operable between a first and a second position, means for operating said reversing switch from one of said positions to the other when said intermittent-motion gear is moved through its reference position, and means for locking said reversing switch in either of said positions selectively when said intermittent-motion gear is away from its reference position.
19.In a drive mechanism in accordance with claim 18 wherein said means for locking includes a pair of con centric circular flanges on said intermittent gear and said reversing switch includes a member pivotable between a first and a second position, and a control pin on said intermittent-motion gear for operating said member from one to the other of said positions, said member having finger portions engageable between said flanges to lock said member in either of said positions selectively.
20. In a tap changing mechanism having a reversible prime mover connected by energy storage and releasing means including an intermittent-motion gear to a movable contact adapted to sequentially engage a plurality of contacts arranged in a circular path, said intermittentmotion gear having a reference position and being rotatable in both directions from said reference position, the combination with said intermittent-motion gear of a pair of concentrically arranged circular flanges on said gear, the outer of said flanges having spaced entrances, a pivoted member having a pair of spaced fingers each disposed adjacent an entrance in said outer flange, said fingers being movable alternately through the spaced entrances to a position between said flanges as said memher is pivoted, a control pin on said intermittent-motion gear engageable with said pivoted member when the intermittent-motion gear is in its reference position to pivot said member in either of two directions to move one of said fingers into the entrance adjacent thereto, and a reversing switch actuated by said pivoted member.
21. A tap changing mechanism in accordance with claim wherein said reversing switch includes a pair of spaced stationary contacts, a shaft, and a movable contact connected to said shaft and arranged to alternately engage said stationary contacts, said shaft having a radially extending arm connected to said pivoted member and being adapted to operate said movable contact into engagement with either of said spaced stationary contacts selectively when said arm is actuated by the pivoting of said member.
22. A tap changing mechanism in accordance with claim 21 wherein a lost motion connection is provided between said arm and said pivoted member.
23. In an electrical switching mechanism of the step type in which a movable electrical contact is moved with rapid motion out of engagement wtih a fixed first electrical contact and into engagement with a fixed second electrical contact, a spring-driven operating means for moving said movable electrical contact, said means comprising a spring and an energy absorbing device operatively connected to said operating means to retard the speed of movement of said movable contact as it moves from said first contact to said second contact, said energy absorbing device including a plunger movable in a fluidcontaining dashpot.
24. In an electrical switching mechanism of the step type in which a movable electrical contact is moved with rapid motion out of engagement with 'a fixed first electrical contact and into engagement with a fixed second electrical contact, a spring-driven operating means for moving said movable electrical contact, said means in- 14 eluding a spring and an energy absorbing device continually operatively connected to said operating means and opposing said spring to thereby retard the speed of movement of said movable contact as it moves in a direct path from said first contact to said second contact.
25. In an electrical switching mechanism of the step type in which a movable electrical contact is moved with rapid motion out of engagement with a fixed first electrical contact and into engagement with a fixed second electrical contact, a spring-driven operating means for moving said movable electrical contact, said means including a spring and an energy absorbing device operatively connected to said operating means to retard the speed of movement of said movable contact as it moves from said first contact to said second contact, said energy absorbing device including a piston movable in a liquidcontaining cylinder having a liquid relief aperture.
26. In an electrical switching mechanism of the step type in which a movable electrical contact is moved with rapid motion out of engagement with a fixed first elec trical contact and into engagement with a fixed second electrical contact, a spring-driven operating means for moving said movable electrical contact, said means including a spring and an energy absorbing device operatively connected to said operating means to decrease the speed with which said movable contact moves into ongagement with said second contact, said energy absorbing device including a piston movable in a liquid-containing cylinder having a liquid relief aperture disposed at a point intermediate the two positions of extreme movement of said piston in said cylinder.
References Cited in the file of this patent UNITED STATES PATENTS 780,496 Elers Jan. 24, 1905 998,953 Capwell July 25, 1911 1,038,990 Trefry Sept. 17, 1912 1,047,277 Nichols Dec. 17, 1912 1,803,653 Rah May 5, 1931 2,009,383 Blume July 30, 1935 2,107,373 Edwards Feb. 8, 1938 2,177,109 Hill Oct. 24, 1939 2,253,183 Le Count Aug. 19, 1941 2,267,394 Butler Dec. 23, 1941 2,480,589 McKenney Aug. 30, 1949 2,605,647 Duvoisin Aug. 5, 1952 2,693,573 Perkins Nov. 2, 1954 FOREIGN PATENTS 382,656 Great Britain Oct. 31, 1932 629,650 Great Britain Sept. 26, 1949