US1664781A - Dynamo-electric machine - Google Patents

Description

April 3, 1928.

G. H. LELAND DYNAMO ELECTRIC MACHINE Fild Nov. 22. 1920 i the so nism.

Patented Apr. 3, 1928.

GEORGE .H. LELAND, F DAYTON, GTIO, ASS

TRIC COMPANY, 033 131:. JTGII,

DYNAIYEO-ELEQT Application filed Novemter This invention relates to improvements in dynamo-electric machines, having SPEClRi. reference to single-phase alternating current motors of the repulsion-starting and ll'lCiUfit tion-running type.

In single-phase, alternating current m tors, the straight repnision type with compensating windings produces, as w known, the most satisfac'iory starting 1 ecteristics, While the indnc on type t": completeiy'short-circuited armature or rotor windin s produces the he 1', operatin oi act tics aside from stat?" These fi ilQi condtiorcs have led to he laroductien rennision-starting. indiiction-ri r in which the arr ture currents and which W We the.

=j soeed, flow through comm :eiiit and, as the motor oppress. speed, the armature coils e short-circuited in parallel I currents are no longer corn. 7

In short-circuiting devices heretofore n in. motors of this character it has is practice to use a centrifugal element n Jued tire to the armature shit and a it generated by the tor to actuate the short-cn'euiti'ng :1

Various IHOVQLJH'CS both rot: axial and a. combination of both. he emp oyed to efi'ect contact of the she writing eieinent with the commutator 1 LG i and disru it the short circuit of tho as ohiect of the present invention is to nnproved SllOIil-CIICULLFQ' lilQCiiiL or repulsion-induction root of the hove referred to whereby simpliciistruction and the highest efficiency 1 tion, both in starting and runnin realized.

' oresent invention also I have used a con the (r i e shaft to control the short-cireuili i moot. but I employ an outwardly dire l. l dial movement of both elements to em Lllt) short-cireuit, and an inwardly di. radial movement to disrupt the iished from the devices of n on shove referred to.

The ..i ruction of the present invention, is simpler and. more economical than What is comm o short-circuiting devices of this charsct so there is increased eiiicienoy some. 1:. earl ier IGNOIB) OF ONE-HALF TC T LELAND ELEG- MACHINE.

Serial No. 495,832.

of operation clue to a positive Wiping contact between the sin eircuitin; element and the commutator acts to keep the contact :31. aces elem rotors to form more effestive center: therebetween. Furti flIDOlQ, t]: action of the contact surfaces ininnn s the tendency to create a. spark when conta t is made or broken. T he I do not cl '1 broad novelty relative to wiping contfzcts. the. construction hero shown is ne ertheless of on improved and highiy 636C? ve character.

@ther objects d advantages realized in my intention v e ornament from the ac: companying d toiled descr ti" o in the d ".n'

Fig. l is an tater of s rem. in inn} 1 tion the commuction motor having i a scuiting mechanism npolied the HOS] of t mechanism h n roir i a better s..- w the rela- ..'.:-n of the psrcs Fig. 2 detail s View taken on "the line 2-2 oi 1, showing the ports in idle or normal inoperative relation;

Fig. 8 is n enhirged double detail sectional VlQW Slf parts in reiative relations at different se s of the short-circuit ing; operation;

3. g 4% is diagrammatic View showing the direction. of forces develoned in the shorteircniting operation. I

. he details oi? motor construction here shown to illustrate the invention consist of the armature shaft 1, rotor 52. commutator ring 3 and segments or hers 4. These parts are common to "IOtOZS O'i this type and may he of any sni o co! motion.

The short-cireniting "iechnnisin of the present invention eon in the form shown in Figs. 1, 2 and V. series of Wedgeshepcd weights arranged circuni't'erentially relative to the Elifllfitl'tlfi shaft and adapted to be moved outwm'dly, radially of the shaft, by centrifugal force as the motor attains speed. When the motor at rest the weights are held in nor ino r tive relation by a ci. .iterentizxiiy arranged tension element 5 which engages the outer ends of the Weights and presses the some inwardly with their inner ends contesting with a sleeve projection 8 of Weight retaining plate '2 arror r' nlescopieoiiy of the armatnre shaft 1. .e outer face of the weights 5 has sliding contact with the plate 7, the inner face of the weights having a lower inwardly extended projection 9 which has sliding contact relation with the lower portion of the outer face of the commutator ring 3, and an upper inwardly extended projection 10 which has sliding contact re lation with the upper portion of the face of the commutator ring and with the outer ends of the commutator segment bars 4:. Thus the weights have sliding contact at three points which provides suitable support for their operation.

As shown in Fig. 1, the weights 5, in their inoperative relation rest with their tapered lateral edges in contact one with another, thus forming a disc made up of the series of weight units. Actuated by centrifugal force generated by the speed of-the motor, the weights move outwardly, substantially radially, against tension element 6, thus bringing the projections 10 into sliding contact with the ends of the commutator seg ments, the spring acting to check or re strain the centrifugal force of the weights and thus to control their movement according to the speed of the motor. The tension element 6 is preferably in the form of a con tractile band and is here shown. as an annu lar helical spring, that is, a helically wound spring having its ends connected one to the other to form an endless band or garter sprin Such a spring is peculiarly adapted to this purpose because it expands uniformly and the convolutions thereof separate as the spring expands and thus remain in substantially the same positions with re lation to the respective weights in all. positions of the short eircuiting element Gen sequently there is little or no friction between the spring and the weights. Further, due to the round or circular cross section of the contractile band it readily rolls up or down the inclined margins of the weights as need be, always maintaining a more or less uniform pressure between itself and the retaining member and between the contact weights and the commutator. Gompared with a contractile band of the clock spring type or of the overlapping spiral band type the helically wound spring is extremely flea ible, permitting it to shape itself to conform to various positions of the weights,

commutator and retaining plate but always maintaining equalized pressure between the respective parts. I

its best shown in Fig. 3, the outer ends of the weights 5 are beveled inwardly toward plate '7. Thus spring 6 is disposed within the angle formed between the bevel of the weights and. the inner face of plate 7, the spring contacting firmly with both surfaces and acting to press the projections 10 of the weights into contact with the commutator segments with increasing force as the wearer weights move outwardly,-the direction of forces employed being illustrated diagrammatically in Fi g. 4; in which A indicates the direction of the centrifugal force exerted on the weights, B the direction of resistance exerted on the weights by the spring, and C the direction of force exerted on the weights at their contact points.

The sliding contacts made by the weights with the commutator segments effects what is commonly known in this art as wiping contactas distinguished from contacts made with a reciprocal movement of the contact elements. The wiping action of the contact elements as here shown serves to keep the contact surfaces clean and thus to efliect better circuit relations, it also minimines the tendency to create a spark when contact is. made or broken,thus increased eficdiency of operation of the motor is realme @peration of the motor, having particular reference to the short-circuiting mechanis'm, briefly stated, is as follows: When the motor is at rest the centrifugal weight elements are in their innermostposition. In starting, the motor operates by repulsion the weights being moved outwardly by centrifugal force as the motor attains speed until contact is made with the commutator, when short-circuiting of the armature is effeeted and the motor operates by induction.

- When the motor falls below operating speed the centrifugal force generated by the weight elements abatcs and the weights under the influence of the resistance spring are retracted, thus breaking the contact with the commutator and disrupting the short-circuit when the motor will again change automatically for operation by repulsion.

I regard my invention broadly as a radical departure in principle and construction from short'circuiting devices of this character heretofore made, having particular reference to the spring-restrained, radially movable weight element-s whereby contact with the commutator is made and broken to effect and disrupt respectively short-circuiting of the armature, and the inclined surfaces which act to exert radial pressure on the spring whereby increased force is exerted on the short-clrcuiting element as final contact is made with the commutator, thus increasing the effectiveness of the wiping action of the contact surfaces and of the circuit thereby established. The principle llU commutator, a contractile tension element supported by and co-acting with the outer ends of said weight elements to restrain the radial movement thereof and acting further on said elements to cause the same to form contact relation with the commutator under pressure.

2. A short-circuiting device for electric motors, including in combination with a commutator, a plurality of weight elements arranged circumferentially' and operable radially relative to the axis of rotation of the commutator, a contractile band supported by and co-acting with the outer ends of said weight elements to rest-rain the radial movement thereof and acting further to exert lateral pressure on said elements to cause the same to eii'ect wiping contact with the commutator.

3. A short-circuiting device for electric motors, including in combination with a commutator, a plurality of weight elements arranged circumferentially and operable radially relative to the axis of rotation of the commutator, a tension element co-acting with the outer ends of said weight elements to restrain the radial movement thereof and acting further on said elements with gradually increasing lateral pressure thereon to cause said elements to eil'ect wiping contact with the commutator.

.4. A short-circuiting device for electric motors, including in combination with the commutator, a short-circuiting element consisting of a series of segmental weights, having inclined outer ends. arranged circumferentially-of and slidable radially relative to the motor shaft through centrifugal action to engage the commutator to effect short-circuiting of the motor, and a circumferentially arranged tension member in engagement With said inclined ends and acting to restrain outward movement of the weights and to force the same against the commutator with increasing pressure.

5. A short-circuiting device for electric motors, including in combination with. the commutator, a short-circuiting element consisting of a series of segmental weights, having inclined outer ends, arrangedcircumferentially of the motor shaft and slidable redially through centrifugal action into engagement with the commutator to effect short-circuiting of the motor, and a circumferentially arranged tension member in engagement with all of said weights and acting to restrain the same in said slidable movement.

6. A short-circuiting device for electric motors, including in combination with the commutator, a short-circuiting element consisting of a series of segmental weights, having inclined outer ends, arranged circumferentially of the motor shaft and slidable outwardly through centrifugal action into wiping engagement with the commutator to effect short-circuiting of the motor, and a. circumferentially arranged tension member in engagement with said inclined ends and acting to restrain said sliding movement of the weights and to force the same against the commutator with increasing pressure as said. wiping engagement is made therewith.

7. A short circuiting device for electric motors including in combination with a shaft and a commutator carried thereby, a centrifugal element comprisinw a plurality of weights arranged circumferentially of said shaft. movable outwardly by centrifugal force and having their outer ends beveled, and a contractile spring element supported by and cooperating with the beveled ends of said weights, one of said elements being electrically conductive and adapted to be moved into short circuiting contact with the commutator, whereby said contact is made with increasing the pressure as the weights move outwardly.

8. A short circuiting device for electric motors comprising in combination with a shaft and a commutator carried thereby. a centrifugal element comprisin a plurality of Weights arranged circum'erent-ially of said shaft and movable outwardly by centrifugal force.,.a spring element arranged,

circumferentially of and movable outwardly with said weights and arranged to exert resistance thereon at an angle to said outward movement, to resist said outward movement and to press one of said elements into contact with said commutator.

9. A short circuiting device for electric motors including in combination with a shaft and a commutator carried thereby, a retaining member supported by said shaft and spaced from the face of said commutator, a series of weight elements arranged circumferentially of said shaft between said retaining member and said commutator and movable outwardly by centrifugal force, each of said weight elements having its outer end inclined toward said shaft and said retaining member. and an annular contractile band engaging the inclined outer ends of said weight elements and said retaining member to press said weight elements toward said commutator and to resist their outward movement by centrifugal force.

10. A short circuiting device for electric motors including in combination with a shaft and a commutator carried thereby, a retaining member supported by said shaft and spaced from the face of said commutator. a series of weight elements arranged circumfcrcntially of said shaft between said retaining member and said commutator and movable outwardly by centrifugal force, each of said weight elements having its outer end inclined toward said shaft and said retainmg member, and an annular helical spring engaging the inclined outer ends of said werg t e ements and. said disk to press said weight elements toward said commutator and to resist their outward movement by centrifugal force.

11. In a short circuiting device for electric motors, a series of commutator bars to be electrically interconnected, a disk arrarged in fixed spaced relation with said series of commutator bars, an annular series of centrifugallv controlled contact members interposed between the commutator and disk, and spring means arranged between said com mutator and said diskand acting on said weights to press the same against said cornmutator and exerting pressure on said disk in a direction away from said commutator.

12. A short circuiting device for electric motorsincluding in combination with a commutator, a plurality of weight elements arranged circumferentially of the axis of said commutator and movable outwardly by contrifugal force", and an annular helical spring arranged circumferentially of said weight elements and engaging the outer ends thereof to resist the outward movement of said weight elements bycentrifugal force.

13. A short circuiting device for electric motors comprising, in combination with a commutator, an annular series of wei ht" elements arranged concentrically with t c axis of said commutator and movable outwardly by centrifugalforce, and a contractile band in rolling engagement with said weight elements and adapted to exert resistance to the outward movement thereof.

14. A short circuiting device for electric motors comprising in combination with a commutator a retaining member mounted in spaced relation to said commutator, an annular series of weight elements interposed between said commutator and said retaining member, arranged concentrically with the axis of said commutator, movable outwardly by centrifugal force. and having portions inclined to the axis of rotation of said commutator, and a contractile band interposed between said commutator and said retaining member, arranged to have rolling engage ment with the inclined portions of said weights and serving to restrain the outward movement of said weights and to maintain them in yieldable contact with said commutator. i

15. A short circuiting device for electric motors comprising, in combination with a commutator, an annular series of centrifugal weight elements arranged concentrically with the axis of said commutator and movable outwardly by centrifugal force, and a contractile band arranged in engagement with said weight elements, adapted to expand uniformly throughout its length and arranged to simultaneously resist the outward movement of said weight elements, maintain the same in yieldable contact with the commutator as they move outwardly and maintain each weight element in a substantially radial position with relation to the axis of said commutator.

16. A short circuiting device for electric motors comprising, in combination with a commutator, an annular series of weight elements arranged concentrically with the axis of said commutator and movable outwardly by centrifugal force, and an annular helical spring supported in rolling engagement with said weight elements and arranged to exert pressure thereon at an angle to said radial movement.

17. In a short circuiting mechanism for electric motors, a series of commutator bars to be electrically interconnected, a disk mounted in spaced relation with said series of commutator bars, an annular series of centrifugally controlled contact members interposed between the commutator and disk, an annular helical spring interposed between said commutator and said disk and in rolling engagement with said series of contact elements, said spring being adapted to re-act.

upon the disk and to simultaneously resist the outward movement of said contact members and maintain them in yieldable sliding contact with the face of the commutator.

18. In a device of the character described,

the combination with a commutator and a retaining member mounted in spaced relation one to the other, said commutator comrising a core and contact bars carried thereof cooperating weight and spring elements interposed between said commutator and said retaining member and cooperating to maintain continuous frictional engagement with both the retaining member and the commutator.

19. A short circuiter for electricmotors, including in combination with a coinmuta tor, a plurality of weight elements arranged circumferentiallv of the axis of the commutator and movable under centrifugal influence to effect the short circuiting of said commutator, and a helical spring, the ends of which are interconnected into an annular band, said spring having engagement with exterior margins ofthe weight elements and against the yielding resistance of which the weight elements move under centrifugal infiuence to effect short circuiting of the commutator.

In testimony whereof, I alfix my signature. GEORGE H. LELAND.

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