US594145A - Iductor-dynamo - Google Patents

Description

UNITED TATES PATENT @FFTCE.

CHARLES P. STEINMETZ, OF SCHENECTADY, NEWV YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEW YORK.

lNDUCTOR-DYNAMO.

SPECIFICATION forming part of Letters Patent No. 594,145, dated November 23, 1897. Application filed August 12, 1897. Serial No. 647,963. (No model.)

To all whom it may concern: of a slot. Thus the magnetism in the latter Be it known that I, CHARLES P. STEINMETZ, case tends to decrease, and this induces eddya citizen of the United States, residing at currents in the whole magnetic structure. Schenectady, in the county of Schenectady, The use of the short-circuited winding, for 5 State of New York, have invented certain reasons more fully to be pointed out, tends new and useful Improvements in Inductorto obviate this difliculty. Dynamos, (Case No. 589,) of which the follow- The accompanying drawings show a maing is a specification. chine constructed according to my invention,

My invention relates to alternating-current it being applied to a dynamo of the well-known IO dynamos of the inductor type, and has for its Thomson induct-or alternator type; but it object to remedy some of the difficulties which might equally well be applied to any other have been met with in designing satisfactory machine of the same general class. machines of this class. In inductor-dynamos Figure 1 is an end elevation, partly in secthe armature and field-magnet coils are station, of such a machine; and Fig. 2 is a side I 5 tionary and the induction is produced by a elevation,partly broken away for convenience change in the path of the magnetic flux efof illustration. fected by the teeth or poles of the rotating In Fig. 1, A is the yoke or external portion inductor. In consequence in part of the magof the armature-core. B is the inductor, connetic circuit the magnetism varies, and this sisting of the usual yoke F and the laminated 20 part, to avoid eddy-currents, must be laminateeth I) b. C C are the armature-teeth, conted, while in the other parts the magnetism is sisting, as is usual in such machines, of lamistationary and solid material may be used. nated iron, the yokeE being ordinarily made It is therefore of importance to avoid changes of cast-iron or mild steel. Surrounding the in magnetism in the solid part of the strucinductor and supported by the yoke are the 25 ture in order to avoid excessive heating and field-magnet coils E E, they being, as is well loss from eddy-currents. understood, stationary. In the machineillus- During the rotation of the inductor the trated each of the armature-teeth is surlength of the path of the lines of magnetic rounded with a single coil D, but this is force, and thereby the reluctance, varies pemerely typical of any selected type or con- 3o riodically in the laminated portion of the arnection of winding. G is the auxiliary airmature, which tends to make the magnetic gap to which Ihave referred in my statement density vary periodically also. To keep this of invention, separating the laminated armaperiodic variation of magnetic density from ture-iron from the yoke E. Between the yoke extending into the solid part of the magnetic F of the inductor and the supporting-yoke E 3g circuit, I insert an auxiliary air-gap between of the armature is the air-gap K, and the the solid and the laminated part of sufficient usual air-gap e is also located between the length to make the magnetic reluctance of the inductor and. the armature. The action of shortest and of the longest path across the this part of my invention will be best underarmature-iron and auxiliary air-gap practistood from Fig. 2. The magnetic lines en- 4o cally equal, and thus the magnetic density tering from the tooth h in the upper part of at the point of entrance into the solid part of the figure and threading the coil spread out the magnetic circuit practically uniform. in both directions in the iron of the arma- Another feature of my invention consists ture, reaching the yoke E at the point .9 in a in the use, in an inductor-dynamo, of a shortpractically straight line from the tooth and 5 5 circuited or squirrel-cage winding surroundat the point 25 over the path 2 which is curved ing the outer edge of the armature-iron. The and is considerably longer than the path 00, magnetic reluctance of the air-gap between having, therefore, higher magnetic relucthe inductor and the armature, especially in tance. The magnetic density at s will be unitoothed singlephase machines, is less greater than at t. By the rotation of the in- I00 50 when the inductor-tooth stands in front of an ductor at the next moment the inductor-tooth armature-tooth than when it stands in front 12 will stand in front of the next tooth of the armature, and the path to the point t will be approximately straight, while that to the point 5 will be curved, and thus higher density will exist at the point '6 than at the point 3. To avoid these pulsations of magnetism in the yoke E is the object of the air-gap G. The reluctance of this gap being very large as compared with the reluctance of the armature-iron (as pointed out in the statement of invention) makes the total reluctance of the path y practically equal to the reluctance of the path or, and thereby insures practically a uniform distribution of magnetism in the yoke.

To assist the effect to which I have referred, I also provide a short-cireuitcd squirrel-cage winding consisting of the copper pins I, Figs. 1 and 2, which pass through the iron of the armature near its outer edge and are connected upon each side of the iron by the shortcircuiting bands II, also of lowresistance metal. Any pulsation or variation of the magnetic flux reaching the outside of the armature acts to induce secondary currents in this short-circuited win ding. These currents tend to magnetize at the points of lower 1n agnetic density and to demagnctize at the points of higher density, and thus cause a uniform distribution of the magnetic flux at the outer part of the armaturethat is, when the flux enters the solid structure. The action of this winding is also beneficial in causing uniform distribution of magnetism and in preventing pulsation of the magnetism in the entire magnetic circuit due to the differences of reluctance in the main air-gap of the machine caused by the revolution of the inductor. As

already pointed out, the reluctance is less when the inductor-teeth stand in front of the armature-teeth and greater when theystand in front of a slot, thus giving rise to changes in the distribution of the flux and inducing eddy-currents in the whole structure.

It has been proposed to remedy this to some extent by Winding the field-magnet coils E upon a solid copper ring or spool. While this is use ful, the construction which I have indicated acts in a more efficient manner because it influences directly the armature-iron of the ma chine.

I'Vhat I claim as new, and desire to secure by Letters Patent of the United States, is-

1. An inductor-dynamo, comprising a revolving inductor and a stationary armature, the latter having portions of laminated iron and a solid yoke, with an auxiliary or additional air-gap in the armature-iron.

2. An inductor-dynamo having a revolving inductor and stationary armature, the armature having on its outer edge a short-eircuited or squirrel-cage Windin g.

S. An inductor-dynamo, comprising a rcvolving inductor and a stationary armature, the armature provided with. an auxiliary airgap in its circuit and a short-circuitcd or squirrel-cage winding near its outer edge.

t. In a dynamo, an auxiliaryor additional air-gap between the laminated and the solid parts of the magnetic circuit.

5. In an inductor-dynamo, an air-gap between the laminated and solid parts of the armature-iron.

6. In a dynamo-electric machine of the in ductor type, the combination of a polar inductor, and an annular magnetic structure recessed to receive the armature-coils and having its magnetic reluctance increased by an air gap or gaps, of high reluctance compared with the reluctance of the armatureiron.

In witness whereof I have hereunto set my hand this 10th day of August, 1897.

CHARLES l. 5"]fllltllllfll7l. Witnesses:

B. 1;. HULL, A. ll'. ABET/L.

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