Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS416191 A
Publication typeGrant
Publication dateDec 3, 1889
Filing dateMay 20, 1889
Publication numberUS 416191 A, US 416191A, US-A-416191, US416191 A, US416191A
InventorsNikola Tesla
Original AssigneeThe Tesla Electric company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Nikola tesla
US 416191 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

(No Model.) 2 sheets-sheen 1. N. TESLA.


No. 416,112.1. Patented Dec. 3, 1889. i

@nez-abr NA PETERS. PhdwLthognphur, Wnhnginn. l)4 CV (No Model.) 2 Sheets-Sheet 2.


ELECTRO MAGNETIC MOTOE. No. 416,191. Patented Deo. 3,1889.

.Line .Za/'ne Fay-7 Wbzyfed: J jazz/enh? g 2W M r h VW@ @wf @M27 My, uawyw.





SPECIFICATION forming part of Letters Patent No. 416,191, dated December 3, 1889.

i Application led May Z0, 1889. Serial No. 311,413. (No model.)

To all whom. it may concern:

Be it known that I, NIKOLA TEsLA, a subject of the Emperor of Austria, from Smiljan, Lika, border country of Austria-IfIungary, residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Electro Magnetic Motors, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.

This invention pertains to that class of electro-magnetic motors invented by me in which two or more independent energizing-circuits are employed, and through whicha lternating currents differing in phase are passed to produce the operation or rotation of the motor.

y One of the general ways which I have followed in carrying out this invention is to produce practically independent currents differing primarily in phase and pass these through the motor-circuits. Another way is to produce a single alternating current, to divide it between the motor-circuits, and to effect artificially a lag in one ofthe said circuits or branches, as by givin g to the circuits different self-inductive capacity, and in other ways. In the former case, in which the necessary difference of phase is primarily effected in the generation of currents, I have, in some ink stances, passed the currents through the energizing-coils of both elements of the motorthe tield and armature; but I have made the discovery that a new and useful result is or may be obtained by doing this under the conditions hereinafter specified in the case of motors in which the lag, as above stated, is artificially secured. In this my present invention resides.

In illustration of the nature of this invention I shall refer to the accompanying drawings, in which- Figures l to 6, inclusive, are diagrams of different Ways in which the invention is or may be carried out; and Fig. 7, a side view of a form of motor which I have used for this purpose.

The diagrams in detail will be described separately.

A B in Eig. l indicate the two energizingcircuits of a motor, and C D two circuits on the armature. Circuit or coilA is connected in series with circuit or coil C, and the two circuits B D are similarly connected. Between coils A and C is a contact-ring e, forming one terminal of the latter, and a brush a, forming one terminal of the former. A ring (l and brush c similarly connect coils B and D. The opposite terminals of the field-coils connect to one binding-post 7L of the motor, and those of the ar1naturecoils are similarly connected to the opposite binding-post c' through a contact-ring f and brush g. each motor-circuit while in derivation to the other includes one armature and one eldcoil. These circuits are of diiterent self-induction, and may be made so in various ways. For the sake of clearness I have shown in one of these circuits an artificial resistance R and in the other a self -induction coil S. Vhen an alternating current is passed through this motor it divides between its two energizing-circuits, The higher self-induction of one circuit produces a greater retardation or lag in the current therein than in t-he other. The difference of phase between the two' currents eifects the rotation or shift-ing of the points of maximum magnetic effect that secures the rotation of the armature. In certain respects this plan of including both armature and iield coils in circuit is a marked improvement. Such a motor has a good torque at starting; yet it has also considerable tendency to syncli'ronism, owing to the fact that when properly constructed the maximum magnetic effects in both armature and lield coincide-a condition which in the usual construction of these motors with closed armature-coils is not readily attained. The motor thus constructed exhibits, too, a better regulation of current from noload to load, and there is less difference between the apparent and real energy expended in running it. The true synchronous speed of this forni of motor is that of the generator when both are alikethat is to say, if the number of the coils on the armature and on the field is fr", the motor will run normally at the same speed as agenerator driving it if the number of field-magnets or poles of the same be also x.

Fig. 2 shows a somewhat modified arrangement of circuits. There is in this case but one armature-coil E, the winding of which main- IOO tains etiects corresponding to the resultant poles produced by the two field-circuits.

Fig. 3 represents a disposition in which both armature and field are wound with two sets of coils, all in multiple varc to the line or main circuit. The armature-coils are wound to correspond with the iield-coils with respect to their self-induction. A modification of this plan is shown in Fig. lL-that is t0 say, the two field-coils and two armature-coils are in derivation to themselves and in series with one another. The armature-coils in this case, as in the previous ligure, are wound for different self-induction to correspond with the field-coils.

Another modilication is shown in Fig. 5. In this case only one armature-coil, as D, is included in the line-circuit, while the other, as C, is shortcircuited- In such a disposition as that shown in y this disposition is modified, coil D being` shown in series with the two ield-coils.

Fig. 7 is an outline of the general form of I motor in which I have embodied this improvement. The circuit-connections between the armature and field coils are made, as indicated in the previous figures, through brushes and rings, which are not shown.

In the above description I have made use of the terms armature and eldg but it will be understood that these are in this ease convertible terms, for what is true of the iield is equally so of the armature, except that. one is stationary, the other capable ot' rotation.

I do not claim in this application themethod or means of operating adouble-circuit motor by making its circuits of diiierent self-induction or in any way retarding the phases of current in one circuit more than in another, having made theseV features subject of other applications; but

NVhat I claim isl 1. In an alternating-current motor, the combination, with field-circuits of diiterent selfinductive capacity, of corresponding armature-circuits electrically connected therewith, as set forth.

2. In an alternating-current motor, the combination, with independent eld-coils of different selt`induction,otl independent arma- =ture-coils, one or more in circuit with the field-coils and the others short-circuited, as set forth.

NIKOLA TESLA. Witnesses:


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2740930 *Jan 11, 1951Apr 3, 1956Haas Johnson Eleanor DeElectric motor
US20060045755 *Aug 24, 2004Mar 2, 2006Dell Products L.P.Information handling system including AC electromagnetic pump cooling apparatus
Cooperative ClassificationH02K17/38