US392765A - Dynamo-electric machine - Google Patents

Description

(No Model.) 2 Sheets-Sheet l.

` E. THOMSON.

DYNAMC ELECTEIC MACHINE.

N0. 392,765. Patented NGV. 13, 1888.

WI T NESSES www@ /u i I'N VEN TCR A TTORNEY,

2 Sheets-Sheet 2.

(No Model.)

E. THOMSON. DYNAMO ELEGTRIG MAGHINE.

WAAAAA jyja A T T ORNE Y Patented Nov. 13, 1888.

NA Pneus Phmmuumgmpmn wmmgem DA cv NITED STATES Perret r @rrr-cn.

ELHU THOMSON, OF LYNN, MASSAGHSETTS.

DYNAMHLECTRiC MACE-HNE.

SPECIFICATION forming part of Letters Patent No. 392,765, dated November 13, 1888.

Application filed .Tuly QG, 1836. Serial No. 209,143. (No model.)

.To @ZZ whom it may concern:

Be it known that I, ELIHU THoMsoN, a citi- Zen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented certain new and use ful Armatures for Dynamo-Electric Machines and Motors, of which the following is a speciiication.

My present invention relates to the manner of applying and connecting the electric conductor that is wound upon the armature of a dynamo-electric machine or motor, and in which the electric currents are generated, or in which the flow of an electric current produces movement of the machine.

As applied to a dynamoeelectric machine, the object of my invention is to permit the generation of electric currents of larger volume for a given size of machine than is practicable with the machines at present in use.

The invention is designed more especially Vfor application to machines of the closed-circuit type-as, for instance, the Gramme, Pacinotti, or Siemens machines-and is of special value in those cases where even with a single layer of wire or conductor on the armature a greater electro-motive force is developed at the brushes than is required when the segments of the commutator are the same in number as the number of turns of wire on the armature.

My invention consists, essentially, in mal;- ing two or morejoints or connections to each turn or length ot' armature-conductor, the said joints or connections being carried, respectively, to different segments of the commutator, as will be hereinafter described. The effeet is to secure a machine in which the nurnber of turns of wire on the armature is less than the number of segments in the commutator.

Another object of my invention is to avoid the local currents developed in armaturesconductors of large diameter or section, which currents heat the conductors and cause great waste of power. Such currents are due chiefly to the fact that the conductors of large section are unequally intluenced at different points in their section by the lield of force, and varying electromotive forces are the result, in the body of the conductor, thereby giving rise to local eddycurrents in the wire conductor itself and causing loss and heating. To avoid such currents, I give to the conductor on the armature, or that part passing through the field, the form of a bundle of insulated wires or wires slightly separated, or touching only at limited surfaces, and also give to the said bun die, between each joint made to it, as a whole, from a commutator-segment one or more halftwists around its anis, whereby the magnetic position of each wire in the bundle is at any one time the same as that of any other in the strand or bundle, meaning by magnetic position average position in the held ot' force upon which at any moment the electro-motive force may depend at any given velocity or change of position. These parts of my invention are applicable to most forms of armature containing a closed coil with connect-ions carried out to a conimntator at intervals, as in Granime type, while the twisting of the strand through one or more half-turns as it passes around the core exposed to the held-magnets may be applied to other armature-windings.

In the accompanying drawings, Figure lis a side view of an armature, showing a turn of armature-conductor applied thereto and connected with the commutator in accordance with my invention. Fig. 2is a diagram illustrating the complete circuits and connections of an armature, such as is shown in Fig. l. Fig. 3 illustrates the application of thcinvention to a so-called ring-armature. Fig. 4 illustrates a cross-section of a ring-armature `and shows the extension of the principle to a case where the length or turn of active conductor has three several connections to three several commutator-circuits. Figs. 5, 6, 7,and 8 illustrate the principle of that portion of my invention which relates to the avoidance of eddy-currents. Fig. 9 is a crosssection of an armature, showing the way in which the conductor may be applied when it is desired to prevent the generation of the local eddy-currents in a ring-armature machine. Fig. 10 is a side elevation ofthe armature shown in Fig. 9. Figs. 1l and l2 illustrate equivalent ways of applying and connecting the armature-con ductor. Figs. 13, la, and l5 show forms of armature-conductor that may be employed in carrying out the invention. Fig. 1G illustrates ainodiiication in which the generation of the eddy-currents is preventedin accordance with the principle of my invention. Figs. 17 and I8 are diagrams further illustrative of my iuvention.

In Fig. l, X X is a shaft bearing an armaturecore, I I, of iron disks or wire which, as shown, of an oblate-spheroidal form, although cylindrical or other forms may be employed if the field-magnets aresuitably arranged. Such core I I is wound with a closed circuit consistingofturnseeeupyingsuccessively different angular positions around the core,as in the Siemens armature and its modifications. It often happens, however, that in large machines the electro-motive force generated in a single turn is greater than is desirable between the commutator-segments, and it is advisable to have more segments than armature-coil turns. In this case I attach to a single turn, as a b, (earried around) two leading-wires to the commutator by joints J J2, such wires being individually carried to adjoining segments in the cominutator K, as shown, and all the other turns as laid on, being connected in regular succession around the commutator by a pair of leading-wires attached, it may be, to each turn, as J J2,in diametrieally-opposite positions on the core. I have shown the leading-wires from the armature-turn to the commutator segment passing downward through the body ofthe armature-core, although this is not an essential of the present invention. By the provision, as shown, of two segments to a turn the number of segments may be twice as many as armature-coil turns. By three or more wires from successive segments attached to each turn of wire on the core at different points the proportion of segments to turns may be still further raised.

Diagrammaticall y Fig. 2 shows the complete winding of Fig. l spread out, where a, b, c, (l, c, f, g, and h represent eight armature convolutions or turns, while K, the commutator, has sixteen segments, thejoint being made by the leading -wires therefrom to the winding at every half-turn.

In a Gramme ring (shown diagrammatically in Fig. 3) the leading-wires to segments from the convolutions of armature-wire on the ring may exceed the number of convolutions likewise, as indicated by the short wires attached to and projecting from the coils of the armature.

As an exemplification of the taking of several leading-wires from one turn of wire surrounding a ring-core and the connecting ofsaid several wires to successive segments on the comniutator, reference may be had to Fig. 4, which represents by I I a section of a ringcore of letter D form, inclosed by a field-pole, N, with a single turn, a b, (one of a closed conducting winding,) having joints J J2 Js to separate'leading-wires ruiming to separate segments in the commutator K, as indicated.

Another part of my invention relates to the saving of loss by eddy or local currents in large arinat-ure-conductors used to convey currents.

A, Fig. 5, represents a short length or section of conductor, forming a small part of the armature winding and embraced between joints J J2 for theleading wires orloops tothe eonnnutator-segments. If such length or seetion A is of one piece of copper of large section, it will become the seat of injurious and wasteful currents not passing into the general circuit, such currents being due to the fact that in different parts of its section different electremotive forces exist, in consequence of the fact that different portions of the wire are at different distances from the field-magnet and pass through fields of a given intensity at different times and with different velocities during revolution of such wire in afield such as N. It has been attempted to obviate such currents by using conductors made up of strands parallel in position; but in only very few cases and to a limited extentis such expedientalone effective. p

In addition to constructing the conductor of several wires insulated laterally from each other, I give a determinate twist to the couductor in passing from J to J2. This twist for the best results should not be less than onehalf turn, and may be as many half-turns as desired. By this means every wire obtains an heavy average of effect equal to and like that given toits neighbor, and an equal potential exists at the extremities of each and every wirein A, where they are united by the joints J J2; hence only the generated current circulates and no eddying action exists; It suffices to give the twist described to the conductor between every two joints, if the portion between traverses a field of neailynniform distribution along the length of the conductor as along A from Jto .l2-or, if the field is regularly distributed, from the middle of A to the right and left toward thejoints. If this is not the case, the twist of a half-turn is `not likely to be sufficient; but several complete turns will usually answer.

Fig. 6 shows the twist in its simplest form, where the conductor is made from two strands only, and is given a simple half-turmas shown, between the joints J J2 for the commutatorsegment connections.

Fig. 7 shows at A a conductor of several strands, and which has been given a half-turn or twist between Jand J2.

Fig. 8 indicates the causes of the existence of currents which are avoided by my invention. In this ease a solid bar conductor is supposed to be moving into a field in the direction of the arrow cl2. The upper or advancing edge cuts the lines of force first and receives a greater impulse of electro-motive force than the lower edge, which is last to enter the field. going in one direction in the forward edge and in the other direction to complete the circuit in the back edge, which current contributes nothing te the general circuit and only heats the conductor.

The result will be a current IOO IIO

@eaves Making the conductor of parallel strands does not get rid of the difficulty; buta halftwist or several half-twists give a substitution of a part of the forward portion for a part of the back portions, and makes the average condition of the parts of the conductor the same.

In applying my invention to conductors on a ring-core, as illustrated in Figs. 9 and l0, it is only necessary that the twisted portion A be that subjected to the iield N during revolution, the other portion, as that part of the conductor passing through theinterior of the ring, as B, consisting, if desired, of a bar.

When the armature-winding consists, as in Fig. l or as in Fig. ll, of a conductor carried around the core and joined to the commutator leading-wires, as indicated, a partial cenipensation in position exists when the conductor is composed of parallel strands, since on one side of the core that strand ofthe eon ductor entering the eld rst is not the strand that is ahead'on the opposite side. It is best, however, to give even in this case severalhalf-twists between joints to effect a perfect compensation.

In the case of the ring-core, wound as in Fig. l2, joints being made on the outside near the middle, and wires carried, as shown, from said joints .I through the core and out at the end of the ring to the commutator, the conductor A may be of parallel strands of wire on the outside of the ring; but at least a half-twist should be given at some part of B, the interior wire of the ring, presuming that ajoint, J, be made for every turn around the core I I.

Fig. 13 simply indicates that the joint .I includes and unites the wire strands of a conductor. Such wires may be replaced by thin sheets or laminas, as indicated in Figs. l and l5, and the joint .I made to include all the sheets, as indicated.

Fig. 1G shows a case in which an average condition and compensation is effected by parallel strands without twisting the conductor. Here a single layer, as two or more wires laid flat and parallel, is wound on the outside of the core, similar to that of Fig. 1 or Fig. ll, and joints are made at .I J2, as before. It will be seen that while a is the advancing or forward wire below the axis A, the other wire,a, is the forward wire above the axis, and if the field-poles are, as usual, diametrically opposite no diiference of electro-motive force will be generated that can canse local or eddy currents to flow in one wire between the joints .I J2 and back by the other wire.

In Figs. 17 and 1S are shown diagrammatically connections similar to that in Fig. 12, but in Fig. I7 no twist or exchange of position has been made in the two strands of the wire located inside the ring, Fig. l2, and shown in Fig. 17 as dotted lines, while in Fig. 1S such exchange has been made, the dotted lines being shown crossed. Currents moving along one of the wires of the strand and bacl; by the other between the joints J J2 may be expected to exist with a conductor arranged as in Fig. 17, as it moves through a magnetic tield,while they will be absent in Fig. 18, because at a the leading strand of the wire is at b also in part last to enter the iield, and the other strands occupy an intermediate position close to one another.

That part of my invention which consistsin making the conductor of one or more strands and giving the same one or more definite halftwisis is not herein claimed, but will be made thesubject ofa separate application for patent.

Vhat I claim as my invention is- I. Ina dynamoelectric generator or motor, the combination, with each single turn or length oi' armature-conduetor, of two or more commutator leading-wires, as and for the purpose described.

2. In a dynamo-electric machine or mot-cr, the combination, with an armature having a given number of tnrns or lengths of conductor, of a eommutator having a number of segments that is a multiple of the number of conductor turns or lengths, as and for the purpose described.

3. In a dynamoelectric machine or motor, an armature-coil turn connected to the comn mutator at two points, both of which are at active or efhcient portions of said conductor, as and Vfor the purpose described.

lI. The combination, with a single convolution of armature-conductor, of two commutator-connections made at diametrically-oppo; site points, as and for the purpose described.

5. Anarmature having commutator-connections that are a multiple of the armature turns or convolutions, as and for the purpose described.

6. The combination, with a cylindrical armature, of an arniature-conductor consisting of parallel strands applied to the periphery ot' the armature and connected to the same coniniutator-segnient, i aid strands being arranged, as described, so that that strand portion of the conductor which on one side of the armature is iirst to enter one magnetic tield shall be on the other side the last to enter the magnetic field, as and for the purpose described.

7. In a cylindrical armature, a conductor consisting of parallel strands connected to the same coinmutatorsegmcnt, the advancing or forward wire or strand of said conductor on one side of the axis being the rear or following strand on the other side, as and for the purpose described.

Signed at Lynn, in the county of lssex and State of Massachusetts, this 21st day of July, A. D. 1886.

ELIHU THOMSON. vWitnesses:

M. Il. Trtoirsow, GEORG-F. J. Gann.

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