US954468A - Winding for electric machinery. - Google Patents

Description

H. & E. ROSENBERG.

WINDING FOR ELECTRIC MAGHINERY. APPLIOATION FILED un: 17, 1904. RENEWED my 28, 1909.

954,468, Patented Apr. 12, 1910.

4 SHEETS-SHEET 1.

H. & EROSENBBRG. WINDING FOR ELECTRIC MACHINERY. APBLIOATION 1 mm mm: 17, 1904. RENEWED my 28, 1909.

Patented Apr. 12,1910.

4 SHEETS-SHEET 2.

H. & E. ROSENBERG.

. WINDING FOR ELEGTRIC MACHINERY. nrmonxon rum) JUNE17, 1904. RENEWED my 28, 1909.

Patented Apr. 12,1910.

4 SHEEIS-BHEET 3.

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H Ill H. 62 E. ROSENBERG. WIRDING FOR ELECTRIC MACHINERY. APPLIUATIOH, FILED JUNE17, 1904. RENEWED MAY 28, 1909.

Patented Apr. 12, 1910.

MEETS-SHEET 4 Jay K9.

- fication of Fig. 1 with a Gramnie armature- Unrrnn STATESPATE1 T'1 OFFICE.

HEINRICH ROSENBERG, 0F VIENNA, AUSTRIA-HUNGARY, AND EMANUEL ROSENBERG,

OF BERLIN, GERMANY.

WINDING FOR ELECTRIC MACHINERY.

Specification of Letters latcnt.

Patented Apr. 12, 1910.

Application filed June 17, 1904, Serial No. 218,015. Renewed May 28, 1909. Serial No. 498,962.

To all whom it may concern:

Be it known thatwe, HEINRICH Rosennnnc, of Vienna, Austria-Hungary, (whose post=oflice address is No. 21 Liechtensteinstrasse, Vienna, IX,) and EMANUEL ROSEN- n'nnc, of Berlin, Germany, doctor of technics, (whose post-office address is No. 59 Brunnenstrasse, Berlin,) both .subjects of the Emperor of Austria-Hun ary, have invented a new and useful Win ing for Electric Machinery, of which the following is a specification.

The present inv'ention'relates to dynamos which, in consequence of the arrangements provided for their excitation, have special advantages in connection with their regulation. In the first place in order that the invention may-be clearly understood, it will be shown that one armature can be influenced by two ma netic fields, so that a double'action takes p ace and the single (1 namo works like adyuamo set consisting 0 main dynamo and regulating dynamo to produce a self-regulating current of constant direction although the direction of rotation and velocity are subjected to variations;

The invention is illustrated by the drawings, in which Fiure l is a diagram of armature coils of difi'erent pitch of poles. Fig. 2 is an illustration 0 a dynamo with one armature acted upon by two magnetic fields of difi'erent pitch of poles. Figs. 3- and 4 are diagrams showing modifications ofthe excita-- 5 and 6 are modifications of tion. Figs.

2 respectively. Fig. 7 is a modi- Figs 1 and winding. Figs. 8 and 9 are modifications of Fig. 6 with a single commutator. Fig. 10 represents a form of dynamo with two magnetic fields of the same pitch of poles atsrig'htangles to each other. 'Fig. 11 the same with a single modification founded on the principle of armature reaction. lFigFs. 13, 14, 15 are modifications thereof, ig. 16 shows. the.

1 same modification in connection with athree wire system. Figs. 17 and 18 are modifications with self-excitation. Fig. .19 shows 'theinvention applied to a motor with means for starting.

' ,-The sel, -regulating action of theillub commutator. Fig. 12 is a drawn trated dynamos-is in close connection twith the remarkable feature that they are able to g ve current of the same polarity for either direction or rotation. It is well known that the polarity of dynamo brushes remains the same, if the magnetic field and the direction ofrotation are simultaneously reversed, for instance if the field of a main dynamo is excited by the armature current of a directly coupled exciter whose field has a constant d rection. In the present invention, however, a separate exciter is avoided and the dynamo itself acts as the exciting dynamo and also as the main dynamo. The problem is to cause two magneticfields to act u on a single armature with one or two win in 5; one field never becomin reversed, so t at a current changing with the direction of rotation is supplied from the armature brushes appertaining thereto, and a second field excited by the above mentioned current and changing therefore with the direction of rotation so that the armature brushes, appertainin thereto have a constant polarity indepen ent of the direction of rotation. In order to attain this re. lt it is of course necessary to causethe direct action of each field on the armature winding which does not appertain'to it to be small. The present invention discovers two ways to attain this result, the one by arranging the two fields and windin 's for a different number of poles, the ot er by arranging the magnetic axes of the two fields, in the case of a two pole field, to be approximately at right angles one to another.

In Fig. 1 it is diagrammatically shown that a two pole drum wave windingand a four pole drum wave winding wound at the same armature can be acted on inductively at the same time by a two pole field and by a four pole field and that the inducingeflfect is the same asif each windin were only acted oninductively by the field of the corresponding number of poles. lhe fine 7 lines 1 and 2 represent the wires forming an element of the two-pole winding, the ful drawn lines. 3, 4,; 5, 6 represent anelement of a four pole drum wave windin The wires 1, 3, 5 are connected respective with commutatorbars c onthe one side and winding may be employed. There is shown also a two pole field a s in fine lines and a.

four pole field N S N 2 S in full lines. It is to be understood that the windin is seen from the interior of the armature t e poles lying behind the wires of Fig. 1. If now the wires are moved to the right hand as indicated by the arrow 7, north pole n will induce in wire 1 a voltage directed downward, south poles in wire 2 a voltage directed lipward. It is true, wire 1 is influenced also by the north pole N of the four pole field, that tends to induce also a downward directed voltage. But as at the same time the second north ole N of the four pole field tends to in ace a downward directed voltage in wire 2 the resulting voltage of the element 1, 2 remains the same as if the four pole field did not exist. The four pole field affects only the E. M. F .s of the single wires 1 and 2 and makes them unequal; whereas the sum of the E. M. F.s is unaffected. In the wires 3 and 5 a downward directed voltage is induced by the poles N and N in the wires 4 and 6 an upward directed voltage by the poles S and S North pole n of the two ole field induces in both. wires 3 and 4 a iownward directed E. M. F., but as they oppose each other the voltage of the whole element is not afi'ected by them. In the same manner the upward I directed voltages in the wires 5 and 6 induced by the Pole 8 of the two pole field have no effect in the sum voltage. field, although acting inductively upon each wire of the four ole windin ,'has no influence on the tota voltage 0 the winding. If now the. two pole field is excited in a constant sense, the current supplied from the two pole armature windin will alter of course its direction if the direction of rota tion is reversed and this current may be employed for the excitation of the four ole magnetic system, so that a rectified current which is independent of the direction of rotation can be supplied from the four pole armature winding.

In Fig. 2 an armature core A is shown, the two windings of which are supposed to be arranged in accordance withFig. 1. The armature has two different commutators c and C, the first belonging to the two pole winding, the second one belonging'to the four pole winding. The right hand commutator 0 is provided with two brushes b I) 180 apart, the left hand commutator O with two brushes B B 90 apart connected The two pole 1) b of the commutator c belonging to the two pole armature winding. A clockwise rotation will produce a current of a certain direction, flowing through the brushes 1) b and the coils F F F F to the effect, that the polarity of the four pole field may be north and south as indicated by the letters N S N 2 S in the Fig. 2 and the main current delivered by the brushes B B may have the direction indicated by the arrows of the conductors H H. When the direction of the rotation is counter clockwise, then the current delivered from the brushes .7) 6 and therefore the polarities of the single poles of .the four pole field will be reversed; but the as Well as the battery Q it is of course also possible to influence the strength of the ,eo.nstant directedtwo pole exciting field by the current or the voltage of the main brushes B B or b any part of the current or the voltage. uch arrangements are shown diagrammatically in Figs. 3 and 4.

In Fig. 3 the armature A is indicated by a line connecting the centers of the two commutators c C. The armature windings and the iron parts of the field magnets are not shown in the drawing. The two pole field is fitted with coils f f excited-from the main conductors H H that lead from the main brushes B B to the outer circuit-consisting of a battery Q and lamps L L. The coils f f produce magnetic lines "indicated; by the onger arrows 8. There are also coils f 1 traversed by the main current in such a direction that they tend to weaken the field produced by the stronger coils f f as indicated by the short arrows 9. By these means the strength of the main current is limited because with the increase of the current the magnetism of the two pole field and in consequence the voltage of the exciter brushes 6 b and therefore the magnetizing current in the coils F F F F of the four pole field is weakened. The current regulates itself and can never reach. an excessive amount no matter whether the speed may be'a very high one or whether the resistance of the outer circuit niay be a very small one. This arran ement with or without a battery is well fit or generators driven with variable speed as in the case of train lighting sistance often varies and in which short circuits occur.

. In Fig. 4 instead of the weakening coils assisting coils f are employed, traversed y a part ofthe main current feedingthe lamps L L and assisting the coils f f as indicated by the arrow 10. By these means a regulation of the field according to the strength of the external current can be It is not necessary to employ separate pole pieces for the two pole and four pole magnetic field. In the first place itis of no importance whether the poles n s of Fig. 1

A are one piece each or divided into two smaller pieces a n s s as shown in Fig. 5. Now, of course, the action upon the wires 1 and 3 will'remain the same, whether they really are influenced by the two diflerent polesn and N or by a single pole, whose magnetism represents the sum of the magnetisms of n and N. In the same manner the action upon. wire 4 will remain thc'same if it is influenced by a single pole whose magnetism represents the difference of the two poles S and a of Fig. 5 that influence the wire. Therefore the two magnetic fields may be combined and the same pole pieces fitted with the coils for the two pole and for ,the four pole field. y In Fig. (3 the two pole armature windingis only indicated by .its commutatofl a smaller inner circle a with two brushes 6 b l80 apart, the four pole armature winding is indicated by its commutator C a larger pole pieces two south poles 8 s result in each that is either the sum or circle with two brushes B B 90 apart. The four ma et pole pieces I, II, III, IV have a doube windin the one exciting winding f which is supp ied with current by a battery Q, generating in the two upper pole pieces north poles a as, in the lower A second winding F is fed from the exciter brushes 1) b and is so connected up that by this winding alone any two neighboring poles would have alternating polarity for instance the polarities ,N S N S indicated in Fig. 6 for a clockwise rotation. Now,'as each of the four pole pieces is influenced by two windings a strength of magnetic field will the difference of both components and ,the dynamo of Fig. 6 will work in exactly the samemanner as the dynamo of Fig. 2. It is possible to go still .one step further, and to supply the exciting current, 'which is to change its direction withthe direction of rotation, from the same Winding and the same commutator as the main current, the direction of which must remain the same durin a change of the direction of rotation.

In ig. '1 .a Gramme winding is indicated by the wires 9 g which are connected with commutator 'bars 0 0 on the one side and with bars O O on the other side. The fields a s and N S N S are corresponding to thoseof Fig. 1. There are shown brushes b .7) on the first commutator at a distance of half the commutator from each other and brushes B B on the second commutator at a distance of quarter of the commutator from each other. Now it is easily to be seen that the voltage between the brushes 7) b is only due to the two pole field n s and is theoretically not afl'ected by the four pole field N S N S whereas the voltage induced in the part of the armature winding between the brushes BB is a'flt'ectedas well by thesouth pole S as-by the right half of the north pole n. that the two pole field is much weaker than the four pole field its influence on the voltage between B B will be but small. If the polarity of the four pole field is re- Provided, however,

versed at the same time with the rotation of v the armature the voltage of the brushes B B will differ somewhat in its value but the direction of the voltage will remain the same. Now, instead of the 2 commutators and four brushes of Fig: 7 a single commutator with brushes may be applied. Fig.8 is a modification of Flg. 6 with a Gramme armature indicated by its commutator G and 3 brushes thereon of which B and B serve as 'exciter brushes, B and B as main brushes. One may have also 4 main brushes as it is usually the case in four pole dynamos with Gramme armature and use 2 of them as main brushes as well as exciter brushes.

In Fig. 9 a Gramme armature G with four brushes B B{ B B is diagrammaticall represented. The four polepieces have di erent windings. The winding ffed by the battery Q, generates in the-pleces I and II north polarity n? n ,in the pieces III and IV south polarity s 8 With this excitation alone the machine represents atwo pole machine, so that between the brushes B and B a difference of potential exists,

whereas B and B would be at the same potential. The four pole winding corresponding to the winding F in Fi 8 is here d vided in two parts F F and t ere is one coil of each part on every pole piece. Both windings F and F between the brushes B and B in such a way, that a current flowing from B through the coils to B would make the pole I a north ole N the pole II a south ole S, the po e III a north pole N and pi) e IV a south pole S a clockwise rotation of the armature. Now the four pole field so produced will be superosed over the two pole field alreadfy exist- The four pole field for itsel would produce in the rotating Gramme-armature a are in series inserted This would be the case for used to produce the four pole field in the manner set forth.' The brushes B and 15* may be connected by'aresistance It. The mains H II are connected on the one hand with the middle I) of the resistance R and on the other hand with the terminal E, in which the ends of thewindings F and F are connected. The main current flowing from B and B respectively through the coils F and F to the terminal has no magnetizing effect, if the coils are equivalent becausc,"for this current, coils F and F oppose each other. It is self evident that for an opposite direction of rotation the currentbctween B and B will change its direct-ion, so the superposed four pole field will be reversed and the direction of the voltage between the terminals E and D will remain the same.

In the preceding illustrations it was shown that two fields with different pitch of poles. may work upon the same armature in the desired manner. The manner of obtaining the object of the present invention according to the second principle consistsin arranging an auxiliary magnetic field the axis of which, if the field be a two pole field, is at right angles to that of the main field. In some cases it may be advisable to halve each pole piece in order to bring all rate windings and commutatorsasindicated the brushes into a neutral zone, as was shown in Fig. 5 with regard to the two pole The armature can'be fitted with twosepaby 0 and O in Fig. 19. The field winding f excited by. the battery Q, magnetizes the pole pieces I. and II as north polesn n", the poles .III and .IV as south poles 8 8 Be tween the brushes 6 'b field magnet coils around the poles II III and IV I. If the armature rotates, there will flow a current from the brushes 6- I) through the coils F F and for clockwise rotation-south poles S S will be superposed in the polepieces' II and III and north poles N N in the pole pieces IV and I.' As in the previous cases we may considereach field as existing independent fr 'om the other and influencing only itsf'own For, the voltage. be-

armature. winding.

. volts, the voltage of t corresponding to this F F are mserted woundfield S S N N 2 exists or not, since north pole N assisting the north pole n raises the voltage of the left upper quarter of the the armature winding appertaining to c as much as the voltage of the right upper quarter is reduced by the pole S opposing north pole at"; and the voltage of the right lower quarter is elevated by S as much as the voltage of the left lower quarter is reduced by N In the same manner the voltage of the vertical brushes B B of the commutator G represented by the outer circle is theoretically in no way directly affected by the field a n s s but only due to the field N N S S As the polarity of the latter poles changes with the direction of rotation, the external current supplied through the brushes B B to the mains H H has a constant direction independent of the direction of rotation.

It is not necessary to apply two different windings nor are even two commutators required; it is possible to connect both sets of brushes with a single commutator G. (Fig. 11.) Then not only a superposition of the fields and of the E. M. F.s but also a superposition of the currents in the armature wlnding takes place. If the strength of the field a? a s s is lower than that of field N N S b pole I of Fig. 11 will be a strong north pole, pole II a weak south pole, pole III a strong south pole, pole IV a weak north pole. Therefore the E. M. F.s induced in the different quarters of the armature winding will difi'er from each other. For instance, the voltage of the left up er quart er may be 51 49', of the rightlower quarter 51, of the left lower quarter 49 volts. The difference of two volts between thebrushes b b will affect the equalizing current flowing 'through the winding F and continuingto reduce the field N N S S. The sa n e e ect can even be obtained without a speclal field winding 1 by making use of the armature reaction alone If the armature brushes 1) b are short circuitcd as in Fig. 12 a current flows through the armature, generating a transverse field which as desired, lies, at right angles to the original field.

Itis well known, that with an ordinary dynamo the armature reaction generates a field that is shifted by 90 against the primary' fieldin the direction of rotation whereas with the motor it is shifted 90 against the direction of rotation. I

Fig. 12 represents a two pole dynamo.-

The upper pole is divided-in two parts .I and II andthe lower pole in two parts III and IV. By the batteryQthe coils f f are supplied wlth current in sucha wa that from the beginning I and II are nort e right upper quarter poles n n 1 whereas III and IV are south oles 8 The cross magnetizing reaction of the armature short circuited by. the crossconnccted brushes 1) 1) tends to weaken the field under the leading pole tips I and III and to strengthen it, under the trailing tips II and IV. In other words, the reaction superposes in tip I an'opposing polarity S in tip II an assisting polarity N in tip III an opposing N in tip IV an assistings Now between the main. brushes B B the superposed field N N S C generates a voltage and as during clockwise rotation the superposed field' will be inversed to that during counter-clockwise rotation the potential of these brushes B B does not become reversed. Thesame effect can be obtained with any suitable armature winding and in various ways. For example: an external current always fiowlng m'the same direction can also ,be obtained b short circuiting the brushes B and B an the brushes B and B as it is shown in Fig. 13. This is merely an imperfect method of carrying out the same inventive idea. i g e The arrangement of Fig. 11 as well asthat of Fig. 12 gives an automatic regulation of the machine. Inboth cases the second magnetic field generated by the current of the auxiliary brushes Z) I) is displaced with regard to the first by plus or minus 90 electrical degreesand the main current flowing through the main brushes B B generates by armature reaction a field, which is displaced through 0 or 180 as compared with the constant directed first magnetic field. That means the armaturereaction of the current driven fluctuates.

flowing through the main brushes B B will either assist or oppose the primary field. \Vith such connectionof windings shown in Fig. strengthen the primary field; In the case of Fig. 12 it will oppose. It is self evident that each of these effects can .be increased by arranging a s ecial field winding traversed by the externa current and that, on the other hand, any desired characteristic of the dynamo can be obtained by such a special winding.

The dynamo according to Fig. 12, the pr1- mary windin of which is separately exc ted, has such a c aracteristic that, when drlven at constant speed, the voltage drops quickly if the main current rises. Its very em].- nently suited for parallel workm with accumulators, if the'velocity at w 10h 1t 1s If, however, the machine is to be constructed for example for the transmission of power without accumulators, it is possible to make its voltage rising with rising main current or remaining constant like that of an ordinary compoun machine, by arranging a main winding, traversed by the main current, to work in the same direc- 11 this 'arn'iature reaction will tion as the separate excited winding, the

effect of which compensates or over-com pensates the counter-action of the armature field. This arrangement is illustrated in Fig. 14, f being the assisting coil traversed by the current of the'main brushes B B.

It will be noticed that the machine, in some respects, possesses the qualitiesof a compensated machine. If the two upper pole pieces are not separated as in Fig. 12 the machine being built as shown in Fig. 15 with common pole pieces PP, the brushes B B will not spark, as perhaps might be expected, because the brushes are situated not in a neutral zone, but in a field n s which is displaced backward b 90 with regard .to

the main field N N 1 S so that it favorably influences the commutation. Thepoles was work as commutation poles'similar to such poles described in various patent specifications.

The arrangement shown in Fig. 15 renders it possible to build the magnetic system with very slight waste of material. The flux which induces the external voltage is generated by the short circuited armature winding and finds its way from the armature through the pole pieces back to the armature. The magnet limbs M and the magnet yoke J carry only a small flux, which must generate the short circuit current between I) b and these can, therefore, have a very small cross section. I

It is perfectly evident that the auxiliary or exciter brushes 1) 1b in Fig. 12, .14 and 15 halve the voltage between the main brushes B B. If, therefore, according to Fig. 16 a conductor h be connected with the short circuited exciter brushes Z2 Z) whereas two other conductors H H are connected with the main brushes B B the three wires H h II with the lamps L L connected between them represent a three wire system directly fed by the dynamo.

For the sake of simplicity it has above been supposed that the primary field wind in which influences the exciter brushes is fe from an accumulator battery or another external source of current. This is, however, absolutely unnecessary, and the exciting winding can be connected in any well known way with the mainbrushes, so that the machine works with self-excitation. This is illustrated in Figs. 17 and 1 8,in the former one the exciting coil f being connect ed in shunt, in the latter one in series to the outer. circuit. The dynamo, in comparison with hitherto known machines, has the advantage that it always excites itself.without reversing switches whichever the direction of rotation may be. If the machme's directlon, they continue to rotate in the same direction. The saving in the material which results from the excltation being produced by the armature is also existent in the case of motors. The starting can take lace in any desired manner, for example by rst disconnecting the auxiliary brushes b and connecting them through a starting resistance, with an external source of current, so

- that the motor runs as a normal motor, and

then gradually short circuiting the brushes 6 b and connecting the brushes B B with the external voltage. This is shown in Fig. 19. The dynamo with a magnet yoke J, limbs M, pole shoes P, an armature winding G, two brushes 6 placed on the usual place and two brushes B B shifted about 90 is used as a motor. H H are the wires coming from the external source of current represented by the battery Q. The lever 11 of the starting resistance has contact pieces 12, 13 and 14, insulated from each other and from the lever. In the position shown the motor'brushes B? B b b are disconnected whereas the field coils f are excitedfrom the line H H If the lever is moved in clock- 'wise direction contact piece 12 will make 24 with brush b Contact piece 14: has no effect. The brushes B -B are in no connection whatever to the conductors H H and the motor runs as a normal shunt motor at first in series with the resistance coils 18 19 and 19 20 that are gradually short circuited. If the lever isin its vertical position piece 14 makes contact between the bars 24 and 25 and. short circuits the brushes 6 6 Piece 12 has left the copper bar 15, piece 13 has left the starting resistance 18, 19, 20 connected respectively with the brushes 6 6 Now piece 12 makes contact between the copper bar lfi'and the bar 26 that is connected to the upper main brush 13 whereas piece 13 makes contact between the copper bar 17 and the terminals of the second resistance 21,- 22, 23 the end 23 of which is connected with the second main brush B This resistance is gradually short circuited.

The different arrangements are shown in the drawings only by way of example. It

, is obvious that the construction can be modi-' fied in many ways. In particular as many poles maybe employed as desired, and the magnetic system can be of any desired form.

It will be readily understood that'one of the machines as above described, if it is .so constructed that the original magnetic field is weakened when the main current increases, will be a .very good primary machine for the'electric lighting of railway carriages, it being driven from the carriage axle. The strength of current remains almost constant, being independent of the velocity within wide limits. The direction of the current remains the same for each direction of driving. It is only necessary to take care that when the train is moving with a very small velocity and when the train stops, the machine is disconnected from the accumulator battery. This can be effected in many well known ways.

-What we claimand desire to secure by Letters Patent of the United States is 1. In an electric machine, the combination with means for creating two magnetic fields, of a single armature-acted upon by both fields, the first field being excited in a constant direction and the second field being excited by a current produced by a rotating winding of the said armature, and current collecting devices connected with the arma ture to lead off to an external supply 'circuit the current generated in the armature by the said second field.

2. In an electric machine the combination with means for creating two magnetic fields of a single armature acted upon by both fields and commutator brushes for collecting separately the currents generated in the armature by the two fields, the first field being excited in a constant direction and influenced by a current derived from the brushes appertaining to the second field, the said second field being excited by a current produced by a rotating winding of the said armature.

' 3. In an electric machine the combination with means for creating two magnetic fields having poles of the same pitch displaced relatively to eaclnother, of a singlearn'iature acted upon by both fields, the first field being excited in a constant direction and the second field being excited by a current produced by a rotating winding of the said .mature by the two fields, the first field being excited in a constant direction by a suitable current and influenced by a current derived from the brushes appertaining to the second field, the second field'being excited by a current produced by a rotating wlndlng of the said armature.

' 5. In an electric machine the combination with means for creating two magnetic fields, of a single armature acted upon b both fields and commutator brushes there or, the

vfirst field being excited in a constant direction by a suitable current and weakened by a current flowing through the brushes appertaining to the second field, the secondfield being excited by a current produced by a rotating Winding of said armature.

(3. In aneleetric machine the combination with means for creating two magnetic fields having poles of the same pitch displaced relatively to each other, of a single armature acted upon by both fields and commutator brushes therefor, the first field being excited in a constant direction by a suitable current and weakened by a current flowing throu h the brushes appertaining to the second field, the second field being excited by a current produced by a rotating winding of the said armature. Z

7, In an electric machine the combination with means for creating two magnetic fields having each thesame number of poles displaced relatively to each other by an angle of ninety electrical degrees, of a sin le armature acted upon by both fields an commutator brushes therefor, the first field being excited in a constant direction and the second field being excited by a current derived from 'the brushes appertaining to the first field.

8'. In an electric machine the combination with means for creating two magnetic fields having poles of the same pitch displaced relatively to each other, of a single armature acted upon by both fields and having a short circuitedwinding, the first field being excited in a constant direction and the second field being excited by a current flowing in f the said short circuited winding of the said armature.

9. In an electric machine the combination with means for creating two ma netic fields having poles ofthe same pitc displaced relatively to each other of a single armature acted upon by both fields, two sets. of

. commutator brushes for said armature, a

cross connection for the set of brushes cor responding to the first field, the first field.

being excited in a constant direction and the second field being excited by a current in a winding of the armature short circuited through said cross connection betiiwlegn the brushes corresponding to the first 10. In an electric machine the combination of a field magnet, an armature providedwith a commutator, commutator brushes and connections short eircuitin the armature ona line displaced throug an angle'of ninety electrical degrees from the medial line of primary field magnetization,

and a second set of brushes displaced through an angle of ninety electrical degrees from the first set, together with an external circuit connected to said second set of brushes.

11. In an electric machine the combination with means for creating two magnetic fields having placed relative y to each other 0 a single armature acted uponby bot-h fields, two sets of commutator brushes for said armature, a crossconhection for the set of brushes corresponding to the first field, the first field being excited in a constant direction and the second field bein excited by a current in a winding oft e armature short circuited through said cross connection between the brushes corresponding to the first field, together with a -three-wire system of distribution, the neutral point of which system is connected to one of said last mentioned brushes.

12. In electric machines the combination with two magnetic fields havin poles of the same pitch displaced relative y other of a single armature acted upon by both fields, the first field being excited in constant direction and the second field produced by the current of an armature winding short circuited through a cross connection of the set of brushes corresponding to the first field, said connection being the neutral point for a three wire system, substantially as described.

13. In electric machines the combination of a field magnet an armature provided with a commutator, commutator brushes and connections short circuiting the armature on a line displaced ninety electrical degrees from the ,line of field magnetization and con nected with the neutral wire of a three wire system and a second set of brushes displaced ninety electrical degrees from the first set and connected to t e'external wires of a three wire system, substantially as described.

14. A direct current dynamo electric machine having an armature, means for creating in the armature two magnetic fluxes, one of which is of constant direction and the other of which reverses when the direction of rotation of the armature is reversed, and current collectin devices connected with the armature to lea circuit the current generated in the armature by the said reversing flux, whereby the generator is enabled to produce a useful external currentof constant directionregardless of the direction of rotation of the armature.

15. In an electric machine, a field magnet, a winding therefor, an armature prov ded with a commutator and brushes, connectlons whereby the current induced in the armature ofi to an external supply.

oles of the same 'iteh disto each i by the field flux I roduces a second magnetization at an ang e to that of the field, and

connections whereby the current induced in the armature by the second magnetization is supplied to an external circuit.

16, In an electric machine, a field magnet, a winding therefor, an armature provided with a commutator and brushes, connections whereby the current induced in the armature by the field flux produces a secondmagnetization at an angle to that of the field,-

and connections whereby the current induced in the armature by the second magnetization is supplied to an external circuit and opposes the magnetizing effect of the current in the field winding.

17. In an electric machine, a field magnet, a winding therefor, an armature provided with a commutator and brushes, connections whereby the current induced in the armature by the field fiux produces a second magnetization at an an}; e to that of the field, and connections to an external circuit at points on the armature equi-potential with respect to the field flux.

18. In an electric machine, a field magnet, a winding therefor, an armature rovided with a commutator and brushes, and connections for connecting in a local closed circuit,

force is supplied to an external circuit and creates 1n the armature a second magnetic field displaced from the first field, and additional brushes and connections through which, the'electromotive force induced in the armature by the second field becomes efiective to reduce the first named field.

20. In a dynamo-electric machine, an armature provlded wlth a commutator, two

sets of commutator brushes, displaced from;

each other by approximately ninety elec-' trical degrees, a field winding producing'a magnetization in line with one set of brushes and thereby inducing a voltage between the second set of brushes, connections for said second set of brushes for producing a second magnetization in line with said second set whereby a voltage is induced between the" first set of brushes, and connections for the first set of brushes for reducing the magnetizing effect of said field winding.

21. In a dynamo-electric machine, an armature provided with a commutator, two sets of commutator brushes displaced from each other, connections from one of said sets of brushes to an external circuit, a field winding producing a magnetization in line with said set of brushes, the current fiowin through said connections ato' said external .circuit producing in said armature a magnetomotive force in opposition to that of said field winding, and connections for 1ncluding the other set of brushes 1n a local circuit.

In testimony whereof we have hereunto set out hands 1n presence of two subscribing witnesses.

HEINRIOH ROSENBERG. I EMANUEL ROSENBERG.

Witnesses:

HENRY HASPER, WOLDEMAR HAUPT.

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