US656127A - Dynamo-electric machine. - Google Patents

Description

No. 656,l27. PatentedAug. -l4, I900. J.'D. SPENGE.

DYNAMO ELECTRIC MACHINE (Application filed Kay 12, 1899.)

(No Model.) 3 Sheets-Sheet l,

Ivwev-oZ'Ene Jknll No. 656,l27. Patented Aug. [4, I900. J. D. SPENCE.

DYNAMU ELECTRIC MACHINE.

(Application filed May 12, 1899.)

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JOHN D. SPENCE, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR TO CHARLES L. COTTON, OF DEDHAM, MASSACHUSETTS.

DYNAMO=ELECTRIO MACHINE.

sPEcrFIcATIou forming part of Letters Patent no. 656,127, dated August 14., 1900.

Application filed May 12, 1899. Serial No. 716,494.. (No model.)

{F9 (055 whom, it may concern:

Be it known thatI, JOHN D. SPENOE, of Somerville, county of Middlesex, State of Massachusetts, have invented an Improvement in Dynamo-Electric Machines, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

10 This invention in dynamo electric machines has for its principal object the production of a novel dynamo whereby a current of substantially-constant electromotive force may be generated at varying speeds of rotation of the armature. \Vith a field of constant or gradually-increasing strength an increase of speed will produce a corresponding rise in the electromotive force of the current generated; but if the field be gradually 2o weakened in proportion to and to compensate for the gradual increase in speed the electromotive force of the current generated may be maintained substantially constant. Prior to my invention attempts have been made to weaken the field for this purpose by the use of a rheostat or cut-out operated either manually or automatically by a governing device responsive to variations in speed of the armature. Attempts have also been made to cut 0 out portions of the armature winding or windings with the same end in View, but, so far as I am aware, all without practical success.

One manner of carrying out my invention is to employ a magnetic shunt, upon which,

5 in addition to the usual coil, is arranged the regulating and neutralizing coil, the latter being in circuit with and energized by an auxiliary armature circuit or winding, said auxiliary armature winding being preferably upon the main armature of the machine and such as ,to produce no appreciable current except at speeds in excess of the normal speed of the armature. At speeds abovenormal this auxiliary armature-winding produces a 5 current which in passing through the neutralizing-coil upon the magnetic shunt more or less (according to the strength of the current) neutralizes the magnetizing effect of the usual shunt-coil, and thereby permits said shunt to more or less weaken the field, so that the increased speed of rotation of the armature produces, owing to the weakened field, a current of substantially the same electromotive force as would be produced by the armature rotating at its normal speed with the full strength of field. The higher the excess of armature speed above normal the weaker will be the field, the resulting current being therefore of substantiallyuniform electromotive force.

In the drawings, Figure i represents in end elevation one form of dynamo-electric machine capable of regulation in accordance with my invention; Fig. 2, a top or plan view of the machine shown in Fig. 1; Fig. 3, a cross-section on the dotted line a; m, Fig. 2; Fig. t, a cross-section taken on the dotted line 00' as, Fig. 2, showing the preferred arrangement of main and auxiliary windings, the armature and brush-holder being in ele- 7o vation; Fig. 5, a diagram showing the several circuits and their connections, and Fig. 6 a diagram showing a modification to be referred to.

Referring to the drawings, in the embodiment of my invention there shown the fields having the two poles A and A and energized by the field-coils B and B are and may be of usual or desired shape and construction.

l At one or both ends of the machine, pref- 8o erably at both ends, as shown, I have applied a magnetic shunt-core C, connecting the opposite poles of the field, said cores at their middle being made hollow or box-like, as usual, for the reception of suitable bearings R, in which are. journaled the opposite ends of the armature-shaft R of the armature R.

The armature R in the present instance of my invention has two sets of windings,which I shall hereinafter designate as the main and auxiliary windings,itbeingunderstood that the term main armature-winding refers to the usual armature-winding composed of one or more coils or circuits employed in connection with the field to produce the main cur- 5 rent of the machine, the term auxiliary armature-winding as herein used meaning the winding which is used, as will be hereinafter described, to energize the neutralizingcoil employed to either directly or indirectly 10o weaken the field for purposes of regulation.

In the machine shown the main armaturewinding 1', composed of a plurality of coils, is of ordinary form, preferably of fine wire, as shown, said winding being connected in usual manner with the commutator m upon the armature-shaft.

The auxiliary armature-winding is herein shown as composed of very coarse conductors 1", connected in the usual manner with the auxiliary comm utatorm, also upon the armature-shaft, preferably at its end opposite the main commutator m. In the construction shown in the drawings the conductors '1" of the auxiliary winding are shown as solid bars of copper or other suitable material inserted between and acting as separators or spacers for the coils of the main winding on tne armature.

Referring now particularly to the diagram Fig. 5, the brushes n and n, cooperating with the main commutator m, have joined to them the opposite terminals of the main conductors or wires 0 0, which include in series the field-coils B B, said conductors or continuations of the same constituting the line-wires 0 0 between which are arranged in parallel the incandescent lamps or other translating devices 1' i. A shunt 0 is also shown passing through and constituting a part of the fieldcoils, as shown, said field having therefore what is commonly known as a compound winding. A second shunt 0 around the brushes a n and preferably of fine wire passes in the form of a coil 0 about each magnetic shunt 0, preferably at or near one end of said shunts-as, for instance, the end adjacent the north pole of the fieldthe direction of winding of the said coils 0 being such that a current passing through the same in the direction of the arrow 5 tends to magnetize the said shunts with north poles at their upper ends adjacent the north pole of the field. The brushes n a", cooperating with the auxiliarycom mutator m,have joined to them the terminals of an auxiliary conductor 1), which passes in the form of a coil P about each shunt 0, preferably at the ends of said shunts opposite the coils 0, said auxiliary conductors 1) also including two preferably-flat auxiliary coils P P shown as let into and lying flush with the faces of the field-poles A A, butwhich, if desired, may be located or arranged in other desired manner adjacent the armature to influence the winding thereof, as will be hereinafter described. The direction of winding of the coils P is such that a current passing through the same in the direction of arrow 6 tends to magnetize the shunts with south poles at their upper ends adjacent the north pole of the fieldthat is, the neutralizing-coils I exert a magnetizing effect upon their respective shunts which is in opposition to the magnetizing effect of the coils O, the coils P thus tending to neutralize the effect of the coils 0. When the armature is at rest, the several coils are deenergized, and the shunt-cores G,being more bars of soft iron or equivalent, serve as conduits through which any magnetic flux may flow from one to the other pole of the field instead of being compelled to jump across from one to the other pole through the armature, as would be the case without the said shunts. The field is thus shunted outs-i. 0., it has no strength, so far as its power to induce a current in the armature-winding is concerned, nor can it have any appreciable inductive power so long as the shunts serve as conduits to conduct the magnetism from one pole to the other. There are, however, sufficient lines of force which do jump across from one pole to the other through the armature to generate a slight current in the main armature-windingr and its circuit 0 0 when the armature is set in motion in usual manner. Immediately as the armature begins to generate a current, however slight, a portion of said current flows through the shunt-coils O in the direction of arrow 5, which current by slightly energizing said shunt-coils tends to set up an independent magnetism of greater or less strength, according to the strength of the'current in the shunt-cores O, the magnetism so set up having its north and south poles adjacent the north and south poles of the field. The magnetism set up in the Held by the current generated and tending to flow from either of the poles to the other through the shunts is therefore at once met with like magnetism at the ends of the shunt-cores C, and therefore the flow of magnetism through the shunts from one to the other pole is retarded more or less according to the strength of the independent and opposing magnetism set up in the said shunts, all the magnetic flux which cannot flow through the shunts being compelled to jump across through the armature, where it will induce more current. As soon, therefore, as the machine begins to generate any current a portion thereof passes through the shunt-coil O to more or less independently magnetize the shunt-cores C, thereby causing more of the magnetism to jump across through the armature to generate in the latter a yet stronger current to in turn again strengthen the independent magnetism of the shunt-core and strengthen the fields, and so on, as the speed of the armature increases, until the magnetism of the shunt-cores equals in strength that of the field, when it will completely bar the passage of any magnetism around through the shuntcores from one to the other pole of the field and will compel the entire magnetic flux to jump across through the armature, thereby bringing the strength of the field up to its maximum and correspondingly bringing the generated current up to its normal electromotive force.

The auxiliary armature-winding I" is preferably so designed that it. fails to generate any appreciable current except at speeds above normal. Therefore if the speed of retation of the armature exceeds the normal the auxiliary armature-wiiuling 1- begins at once to generate a current in the auxiliary circuit 19, flowing in the direction of arrow 6, such current acting, as described, to set up a counter magnetism in the shunts-that is, a magnetism in opposition to and tending to neutralize the magnetism of the said shunts set up by the said shunt-coils O.

The neutralizing power of the auxiliary coils P depends entirely upon the strength of the auxiliary current, the neutralizing effect being greater with a strong current than with a weak current, and as the speed gradually increases above the normal the auxiliary current in the coils P gradually strengthens and to a greater extent neutralizes or lessens the effectiveness of the magnetism set up in the shunts by the coils 0. As the magnetism of the shunts set up by the coils O is gradually neutralized or weakened by the opposition of the neutralizing-coils P, said shunts will therefore gradually lose their power to hold back the field magnetism and will again act to a greater or less extent as conduits for the passage of the field magnetism from one to the other pole to thereby weaken the inductive power of said field. When the speed of rotation of the armature is increased. to such an extent that the auxiliary current in the coils P completely neutralizes the magnetism of the shunts set up by the current in the coils 0, then the said shunts will, in effect, have the same influence upon the field as before the machine was started-that is, they will completely shunt the field, depriving the main armature-winding of its power to generate current. To prevent the machine turnin g over or reversing its polarity at this point, owing to the lack of magnetism in the field and the presence of a strong magnetizing tendency of opposite polarity in the shunt, I have provided the auxiliary field-coils P 4P which receive their energizing-current from the auxiliary armature-winding and circuit 19, said coils being in series with said auxiliary winding and acting like a series machine to keep the dynamo-machine in operation and to prevent the disastrous effects resulting from a reversal of polarity and the like.

From the above description it will be seen that the auxiliary armature-winding with its auxiliary coils P on the shunts does not in any peculiar manner affect the operation of the machine until the speed of rotation rises above normal, but that at once upon increase of speed above normal the auxiliary armature-Winding begins to generate a current, which acting through the auxiliary coils P on the shunts neutralizes the magnetizing effect of the current in the shunt-coils O, and thereby causes the said shunts to weaken the field in proportion to the increase of speed of rotation of the armature, a gradually increased speed causing the field to be made gradually weaker, so that the ordinary effect of an increase of speed-viz., the production of a current of higher electromotive forceis in my invention counteracted by the weaker field,which thereby causes the electromotive force to remain practically constant. The machine because of the compound winding of its field is self-regulating so far as variations in resistance is concerned, and by means of the neutralizing-coil, forming part of this my present invention, the machine is rendered practically self-regulating or constant also as to variations in speed.

By means of my invention, which enables the machine to be run at varying speeds without changing the electromotive force, I am enabled to utilize dynamos for many purposes for which it is impossible to employ machines at the present time as at present constructed. For example, they may be operated from the wheels of a moving railwaytrain and produce at varying speeds of the train always a uniform electromotive force. By means of my invention machines may be operated from power plants now in existence and which do not have sufficiently fine or perfect regulation as to speed as is as at present constructed.

In Fig. 6 I have shown a construction differing from that in Figs. 1 to 5, inclusive, yet embodying, essentially, the same principle of regulation.

In Fig. 6 the machine has four poles ff f f each surrounded by a field-coil, said coils being arranged in series, as shown, with the commutator-brushes f f of the main armature-winding. Two of the poles-as, for example, f and f-are'provided also with neutralizing-coils g g in circuit with the com mutator-brushes of the auxiliary armaturewinding. The auxiliary armature-winding at excesses of speed generates a current which acts in the coils g g to more orless neutralize the two field-coils on the poles f and f, thereby more or less demagnetizing said poles and leaving the two poles f and f of the same polarity at their full strength, which of course weakens the field in the proportion to which the poles f andf are weakened, for the machine cannot operate with poles of the same polarity. My invention therefore is not necessarily limited in its application to means of slight modifications, which will be apparent to those skilled in the art, my invention is applicable to all forms of generators whether having two or more poles and of whatever construction.

WVhile I prefer to arrange the auxiliary field-coils P and P in the faces of the poles of the field substantially in the manner herein shown, yet it should be understood that the said coils may be otherwise arranged so long as they are in such proximity to the rotating armature as to produce a current in the auxiliary armature-winding in the manner herein described.

For many purposes the auxiliary armaturewinding may be used in combination with the auxiliary coil P upon the shunt without considered essential for operating machines machines of any particular class, for by the auxiliary field-coil P P such a construction operating effectively to maintain the electromotive force constant up to certain speed limits within the limit at which the field becomes demagnetized or shunted out by the complete neutralization of the shunt; but for the most perfect regulation the auxiliary feedcoils should be employed to guard against turning over or change of polarity of the machine.

WVhile the spacing-bars 0" between the coils of the main armature-winding furnish convenient conductors for the auxiliary armature-winding, yet this invention is not restricted in this respect, as the auxiliary windings may be formed of coils orconductors arranged as shown or in other desired manner to produce the result herein described and for the purpose herein referred to.

I consider myself to be the first to employ a coil surrounding a magnetic shunt for the purpose of reducing the shunting or weakening effect of said shunt as the machine attains its normal speed, in combination with a neutraling-coil to counteract or neutralize the said first-named coil as the machine exceeds its normal speed, and thereby again restore to a greater or less extent the shunting or weakening effect of said shunt and weaken the field, so as to compensate for the greater speed. I further consider myself to be the first to weaken a field either directly or indirectly by the use of an energized neutralizing-coil.

In the claims the term neutralizing-coil is employed to designate a coil in which a current acts inductively to weaken the field, whereby the desired result is obtained, as distinguished from a coil which when energized operates through mechanical means to cutout more or less of a circuit or change the position of some mechanical device to effeet the regulation desired. In Figs. 1 and 5 this energizing coil (or coils) acts indirectly through the shunt to weaken the field. In Fig. (3 the said coils act directly upon and to weaken the field.

I do not herein claim a method as such, inasmuch as it forms the subject-matter of a separate application.

Having fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In a dynamo-electric machine, an arn1ature, a plurality of field-poles, exciting-coils therefor, a magnetic shunt for shunting poles of opposite polarity, a shunt-coil encircling said magnetic shunt and in circuit with an armature-winding to reduce the shunting power of said magnetic shunt, and a neutralizing-coil normally of slight effect also encircling said magnetic shunt and adapted when excited to neutralize or counteract the effectof said shunt-coil, substantially as described.

2. In a dynamo-electric machine, an armature containing main and auxiliary windings, a plurality of field-poles cooperating with said main arinature-winding to produce a main or working current,and means controlled by said auxiliary armature-winding for weakening the field for and proportionately to excesses of armature speed, substantially as described.

3. In a dynamo-electric machine, an armature containing main and auxiliary windings, a plurality of field-poles, and exciting-coils therefor, a magnetic shunt for shunting poles of opposite polarity, a shunt-coil encircling said magnetic shunt and in circuit with said main armature-winding, said shunt-coil acting to independently magnetize and thereby lessen the shunting or weakening power of said magnetic shunt; a neutralizing-coil also encircling said magnetic shunt and in circuit with said auxiliary armature-winding, said neutralizing-coil when excited acting in opposition to said shunt-coil to neutralize the magnetizing effect of the latter and thereby more or less restore the shunting or weakening power of said magnetic shunt and more or less weaken said field-pole, substantially as described.

4. In a dynamo-electric machine, an armature; a plurality of field-poles and main exciting-coils therefor; a magnetic shunt for shunting two poles of opposite polarity, a shunt-coil encircling said magnetic shunt and when energized acting to independently magnetize and thereby lessen the weakening power of said magnetic shunt; a neutralizingcoil also encircling said magnetic shunt and when energized acting to counteract or neutralize the magnetizing effect of said shuntcoil and thereby cause said magnetic shunt to Weaken said field-poles; and one or more auxiliary field-coils excited independently of said main field coil, substantially as described.

5. In a dynamo-electric machine, an armature containing main and auxiliary windings; a plurality of field-poles, and main excitingcoils therefor; a magnetic shunt for shunting two poles of opposite polarity; and a shuntcoil encircling the same, said shunt-coil when excited acting to magnetize and thereby lessen the weakening power of said magnetic shunt; a neutralizing-coil also encircling said magnetic shunt and when energized acting in opposition to said shunt-coil to cause said magnetic shunt to weaken said field-poles; and one or more auxiliary field-coils in circuit with and excited by said auxiliary armature-winding, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN D. SPENCE.

\Vitnesses:

JOHN C. EDWARDS, AUcusrA E. DEAN.

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