US1243966A - Dynamo-electric machine. - Google Patents

Description

L. CE NCHOLS.

DYNAMO ELECTRIC MACHINE.

APPLICATION FILED IAII.22, 1915.

` UNITED sTATiis PATENT orFIcn.

LOUIS C. NICHOLS, OF NORWOOD, OHIO, ASSIGNOR TO ALLISr-Cl-IALMERS MANUFAC- TUR-ING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

DYNAMO-ELECTRIC MACHINE.

Specification of Letters Patent. Patented Dect. 23, 191'?.

Application filed January 22, 1915. Serial No. L,069.

T 0 all 10.3 t may concern.'

Be it known that I, LOUIS C. NICHOLS, a citizen of the United States, residing at Norwood, in the county of Hamilton and State of Ohio, have invented a certain new and useful Improvement in D ynamo-Electric Machines, of which the following is a specilisation.

This invention relates in general to dynamo-electric machines, and has particular reterence to such machines, as are of the projecting'-.pole type and wherein it is desirable that the reluctance of the magnetic circuit of a iield pole be adjustable.

In designing the electrical and magnetic features of a dynamo-electric machine so that a certain flux density be produced in the field poles, it is often dilticult to obtain exactly the desii'ed magnetic conditions. livhile it might be possible, Where the exciting winding is of the shunt type, to change the number 'of turns or insert a resistance 'in series with the winding, nevertheless, where the winding is-of the series type, a winding ot which type very often consists of but a con'iparatively small number of Aturns or fractional turns, it is inexpedient and undesirable to vary the number of turns or to insert a variable resistance inl In some cases fairly good'oi'ieration might be secured by series with the winding.

arranging a reactance in shunt to the series winding, provided such shunt has a time Aconstant equal to that of the Winding itself, so that a constant ratio would exist between the currents in the winding` and in the shunt reaclanee, without which condition the operation ot' the machine would be unsatisfactory, t'or the flux produced would not always be proi'iortional to the current in the'winding or, consequently, the load upon the machine. Again, under certain conditions, even though the time constant of the shunt reaetance were designed to be equal to that of the winding, it is probable that, due to the shunt reactance being ordinarily rc- Inoved from the immediate vicinity of the machine, the temperatures of the Winding and the reactancc would vary at different rates, and, hence, the current in the winding would not always be proportional to the current supplied by the machine.

rflic best operating results along with the most econ'on'iical construction-exists when the-winding is oi jiist such dimensions as to produce the proper flux at all times, as the load on the machine varies, without resort to resistance or reactance in series with or in shunt to the winding, and when the pole and windings are o't as small dimensions as possible to secure the desired results, since econoi'iiy in construction is best attained by maintaining the field structure of as small size as possible, while'securing the desired results. Further, the air gap adjacent the armature should be. maintained at a minimum to reduce leakage between adjacent pole tips to a minimum.

The more desirable advantages of this inrventiony are attained in connection with dynamo electric machines provided with commutating poles effective to produce a magnetic flux in line with the armature coil undergoing` commutation and of such intensity as to compensate for armature reaction and` ordinariiy, to produce ay iield of the required amount to induce current in such short-circuited coil that is of approximately the saine value as is present in the effective armature coils when the short-circuit is removed from the coil undergoing commutation. llnless this winding is ot the proper dimensions to produce the required commutating luX, which will vary as the load varies, the commutating Winding being in series with the mains, sparking will occur at the brushes.

It is an object of this invention to provide an improved construction of dynamoelectric machine wherein the fieldA poles are provided with [lux producing windings ot a. lixed number ot turns, und wherein, with constant. current in such windings, the ilux produced thereby may be variedby means other than a resistance or reactance associated with said winding.

lt is a further object of this invention to provide a construction of dynamo-electric machine embodying improved means for varying the reluctance of the magnetic path of a field pole.

It is a furtherobject otithis invention to provide an improved construction of dynan'io-electric machine wherein the air gap between a field pole and the armature may be maintained constant and the reluctance ot the i'nagnetic path of the pole may be varied.

lt is a tui-ther object 0I' this Ainvention to provide an improved construction of dynanio-electric machine wherein the field poles are of substantially solid construction and are of variable reluctance.

These and other objects are attained by this invention, the various novel features or". which will appear trom the description and drawings forming a part o this specification, and will oe particularly pointed out in the claims.

In the accompanying drawings:

Figure 1 is an end elevation, with parts in section, of a` portion of a dynanio-electric machine embodying; features of this invention..

Fig. Z is a perspective View of a portion of a ield pole oli the machine shown in Fig. 1.

Fig. 3 is a perspective View of a modified form of a. detail of the construction shown in Fig.. 1 and. 2.

In the drawings,` there isdisclosed a dynamo-electric machine .having a rotating armature, 11 `ane a. field frame or yoke -12 provided with projecting main poles 18 haring windings 14. lso secured to the jranre 12, intermediate the main poles 13, are commutating poles 15 provided with windings 16. Ilaeh commutatinoj pole comprises a body portion 17, to the radially inner end of which may be secured a pole shoe 1S, and plurality ot separate disks or laminations 19, 19u, secured in position intermediate the body portion 17 and the it'rame 12 by t bolt or screw 2l, which passes through the iframe 12 and the lan'iinations 19, 19a. and is threaded into body portion 17, this bolt serving to hold the parts of the oonnnutating pole in operative position..

he laminations or disks 19, 19.l ar, ordinarily,of both magnetic material and noninagnetic material. 1t may be considered that 19 indicates those of magnetic material and 19,l those of nonemagnetic material.. lVliile, in order to maintain the air gap bew tween the pole shoe 18 and the arnnxture 11 constant. it is necessary tha t 'the space oecupied by the laminations 19, 19a7 at all times, be of the same vradial extent', neverthele it will be obvious that by rallying` the pro portion of magnetic laminations to nonniagneric laminations, 'the reluctance of the connnutating pole may be varied. is will be apparent, this may be acconnilished by substituting for a certain number of laminations of magnetic material an equal aumber oi laminations of non-m a gnetie material, or vice versa.

These laminze 19.` 19m are of substantially the same cross-sectional area as that of the body portion 17E and. while they may be ln'ovided with closed slots for the reiI "on oi the screw or bolt 21, which construction requires insertion and removal of the laminations by -a movement parallel to the axis of the screw or the insertion of the screw through the previously assembled body portion 17 and laminations7 they are, preferN ably, provided with an open siot. as indicated at E23y this slot extending` parallel to the axis of the machine when the laminations are in opcratire position on the body portion 17. Such an arrangement provides for tue utmost facility in removing la1nina tions Ytroni and inserting the same to opera* tive position from the end oil the machine, which operation may be accomplished on loosening` the bolt or screw 21 to a slight extent. However, as indicated in Figr. 37 these laminations 191 may he slotted along the longer side, so as to permit insertion and remoiiil of tle saine in a eircumterential direction, desired5 the slot beingdeftig .nated llt will be obvious that., at all times, independently oit the number and magnetic qualities of the laminee, the eross-sectional area. of the pole is the saine throi'xfrhout :its lengt-h from the pole shoe to the trame lf2. and that this pole sunstantially solid throughout its length. 'l'lns latter feature is oit' advantage in that there is a solid and snbstaiuial bearing for the comparatively heavy body portion 17. and such a, hearing that. while capable oi being` varied, will oiier no dilliculty in maii'ltnining the air gap between the pole shoe and 'ine armature substantially constant. rthere is a decided adrantage inV having' the pole piece ol suhtantially the same cross-sectional ar 2a throughout its entire length, in that the ysmallest and most economical type oli se es eeil can be utilized, the coil fitting' readily oper either the body portion 1i' or the laminations 19,

ln ordinai 7 design. 'the cross-section o'l" the series winding; is i'iXed to a ,creat extent hy the maximum cin'rent which the nnufhine is intended to furnish. This winding' should be oit such cross-section tl at itl can safely carry this maximum current without any considerable heating'. Consideringl the crossH section of the series r-iinding as fixed, and that the preliniiiutry' design isuflicaies that say turns o? winding are nlm/fassaryY io secure the required, connnntalinn linx, the connnutating poles being); eonsiefned as bcing` of magnetic material tln'ol hout the .'t'ull length7 it wiil he apparent that since it .not all iieasile provide a fractional turn about tne canmutating; polej the quired iiu `musthe produced with 'four full turns of the winding. 'ilere the full, line current to through Jdiese four ull turns, the .eitation produced wonld be greater than that required. and hence, it if; necessary 'to reduce this excitation. This niightbe done by plating` a resistance. inductive or non-inductive. in shunt to the lwhaling, but. as stated above. both oit' these expediente have undesirable features. In

Sti

-cured in position.

messes accordance with this invention, the required flux may be secured by using four full turns of Windingrand by increasing the reluctance of the pole to the extent that the magnetic effects due to the four turns are the same as that which might be obtained with turns, using a pole wholly of magnetic material. This required effect is produced by replacing a portion of the laminations of' magnetic material 19 by laminations lof nonmagnetie material 19a, without varying the total radial space occupied by these laminations.

ln most cases, the proportion between these laminations lf) and 19,l is calculated in advance, and the pole, made up of the bodv portion 17, the pole shoe 1S, and the laminations 19 and 192 and the winding 16, is sen The `machine is then tested, and, if the eommutating flux produced is notl exactly that required, adjustmentis made by exchanging one or more laminations of magnetic material for a number of laminations of non-magnetic material whose total thickness is equal to that of the laminatiors of magnetic material which have been removed, or vice versa. Again, adjustmen; may be made by substituting for one lamination, a lamination of equal thickness and of magnetic properties that differ to the required extent to produce the desired result. 1t will also be obvious that further adJustment may be made by substituting for two laminations,two other laminations, one of magnetic material and the other of non-magnetic material, or two laminations of different material and of such relative thickness as to produce the required result.

It will be obvious that those laminations 'that nave been described as beingl of nonhaving different magnetic properties from the material of' the other laminations.

Where the machine is of a type requiring comparatively few series turns, it be desirable that the so called non-magnetic laminations be actually of a comparatively non-magnetic material, such brass, and hence be capable, on substitution of one non-magnetic lamination for a magnetic lamination, of causing considerable change in the total reluctance of the magnetic circuit of the pole; and, Where a greater uunber of series turns are required, it may be desirable that the non-magnetic7 laminations, While of considerably less permeability than the magnetic laminations, be of a material, possibly an alloy, of greater permeability than air.

It will be obvious that, in accordancey with this invention, the required amount of series field flux may be produced, and that the flux produced by a winding of giver.` dimensions may be varied other than through the use of resistance, either in series or in shunt to the windine', and that the air gap between the field pole and the armature is maintained constant and the pole is sub-v stantially solid and ot' the same' cross-sec- 7C tional area throughout its full length.

it should be understood that it is not desired to be limited to the exact details of' construction shown and described, for obvious modifications will occur `to a pen-:on 7; skilled in the art. l

it is claimedv and desired to secure by Letters latent:

1. in a dynamo-electric machine` a trame, and a field pole secured in position rela- 8G tively to said frame; said pole being of substantially uniform cross-section throughout its entire lengt-h and one portion of said pole being made up of a plurality of laminary having different magnetic properties and S extending substantially perpendicular to the axis of said pole throughout substantially the full cross-sectional area of the pole.

2. in a dynamo-electric machine, a frame, a field pole secured in position relatively to said frame, said pole being` of substantially uniform cross-section throughout its entire length, one portion ot' said pole being made Aup of a plurality of laminadisposed in planes substantially perpeiulicular to the 9 axis of said pole and extending throughout the full cross-sectional area of the pole, said laminas being removable from and insertible to position without removing another portion of said pole from said frame', and conimon means for holding the latter portion and said laminae in operative position.

3. ln a dynamoelectric machine, a frame, a field pole comprising a plurality of por y tions of different magnetic properties, and 1.35 means for securing said portions together to form a pole of substantially solid construction and for securing said pole in ope ative position relatively to said frame, one of said portions being removable and replaceable without necessitating shifting of another portion.

1l. In a dynamo-electric machine, a yoke, a pole piece, means for supporting said pole piece from said yoke, said-pole piece comprising a body portion of magnetic material spaced from .said yoke, and means occupying substantially the entire space between said body portion and said yoke for spacing said body portion from said yoke, said latter means con'iprising a plurality ot' laminations held in position by the support ing means for said body portion.

.5. ln a ilyn:\m .)electi'ic machine, a yoke, a pole pir-w. means for supporting saidpole 125 piece from said yoke, said pole piece comprising abody portion of magnetic material spaced from said yoke, and means occupy ing substantially the entire space between said body portion and said yoke for spacing 13g said body portion from said yoke, said latter means comprising a plurality of laminations of material having different magnetic properties.

6. In a vdynamo-electric machine, a yoke, a pole piece, means for supporting said pole piece from fsaid yoke, said pole piece coniprising a body portion of magnetic material. spaced from said' yoke, and means occupying substantially the entire space between said body portion and said yoke for spacing said body portion from said yoke, said latter means comprising a plurality of laminations of the slime cross-sectional area and shape as said body portion and ot' diilerent magnetic properties.

7 In a dynamo-electric machine, a yoke, a pole piece, means for supporting said pole piece from said yoke, said pole piece comprising a body portion of magnetic material spaced from said yoke, and means occupying substantially the entire space between said body portion and said yoke for spacing said body portion from said yoke,

said latter means comprising plurality o'i Alaminations of substantiallythe saine crossi sectional area as said body portion and of diil'erent magnetic propertiesmnd said laminations being held in operative position by 30 the supporting means for said body por tion.

8. In a eoinmutating dynz'nno-electric machine, the combination with the yoke of the machine and its main polar projections, ot

35 connnutating polarportions interposed between said main polar portions and secured to said yoke, and windings surrounding said commutating polar portions, each of said commutati-iig polar portions comprising a body portion of magnetic material adjacent the armature of said machine and a plurality of laminations of different magnetic properties and the same cross-sectional area andy shape as said body portion and disposed similarly to said body portion, said laminations being secured in position between said body portion and said yoke.

9. In a coinmutating dynamo-electric machine, the combination with the yoke of tlie machine, of a commutating pole piece attached to said yoke and comprising a body portion or" magnetic material adjacent the armature or" said machine and a plurality of laminations of different magnetic properties and of the same cross-sectional area as said body portion and disposed between said body portion and said yoke, and coininon means for holding said body portion in operative position and for securing said laminations between said body portion and said yoke.

lO. In?J a coininutating dynamoelectric machine, the combination with an armature and a yoke, of a eominutating pole piece, a winding therefor through which substantially all of the current generated by the-A machine passes, said pole piece eomprisinlg portions of dil'l'erent magnetic properties and being of substantially solid construction when in assembled condition and oi uniform cross-section throughout its entire length, and means for securing said portions together and. said pole piece to said yoke.

ll. In a dynamo-electric machine, a yoke, a. pole piece, means for supporting said pole piece ifi-oni said yoke, said pole piece coinprising a body port-ion of magnetic material disposed adjacent the arii'iature of the niachine, and means occupying Jsubstantially the entire space between said body portion and a. portion associated with said yoke and spacing said portions apart, said latter means comprising a plurality ot laminations held in position between said body viliortion and the portion associated with said. yoke.

l2. In a dynamo electric machine, a trame, a iield pole oll substantially solid construction and comprising a body poi'- tion disposed adjacent the armature of the machine, and portion disposed between said body portion and said traine and comprising a plurality of laminations of substantially the same cross-sectional area. as said body portion, and means disposed within the periphery of said pole :lfor securing said body portion in position adjacent the armature and said laminations in position between said body portion and said frame.

In testimony \'hereoi, the signature of the inventor is aliixed hereto in the presence of two witnesses. Y

LGUIS C. NICHOLS. Witnesses JOHN C. Davimron'r, Guo. F. 'l-nire.

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