US678191A - Alternating-current dynamo. - Google Patents

Description

No. 678,!9l. Patented July 9, Hill. I]. McF. MOORE.

ALTERNATING CURRENT DYNAMO.

(Application fllgd Apr. 13, 1901.)

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ALTERNATING CURRENT DYNAMO.

(Application filed Apr 18, 1901-) 5 Sheets-Sheet 2.

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D. IMF. MOORE.

ALTERNATING CURRENT DYNAMD.

(Application filed Apr. 18 1901.)

(No Model.)

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ALTERNATING CURRENT DYNAMO.

(Application filed Apr. 18, 1901.)

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UNITED STATES PATENT OFFICE.

DANIEL MCFARLAN MOORE,'OF NEWARK, NEW JERSEY, ASSIGNOR TO MOORE ELECTRICAL COMPANY, OF NEW YORK, N. Y.

ALTERNATlNG- C-Ul iR EN-T DY NAM o.

SPECIFICATION forming part of Letters Patent No. 678,191, dated July 9, 1901.

Application filed April 13, 1901. Serial No. 55,683. (No model.)

To (LZZ whmn it may concern.-

Be it known that I, DANIEL MOFARLAN MOORE, a citizen of the United States, and a resident of Newark, in the county of Essex and State of New Jersey, have invented a certain new and useful Alternating-Current Dynamo, of which the following is a specification.

My invention relates to the construction of a dynamo electric generator particularly adapted to produce a form of varying electromotive force especially adapted for use in vacuum-tube lighting and for other purposes.

The object of the invention is to produce a dynamo-machine capable of developing waves of electromotive force rapidly varying in their succession, which waves or pulses may conveniently be stated as being of peaked form and as distinguished from the forms of wave or impressed electromotive force developed by ordinary dynamomachines and also from the form developed in the machine patented to me by Letters Patent No. 644,995 in that each pulse'of the electromotive force instead of beginning to ride immediately after the zero-point of the succession of waves continues for a considerable portion of the time between zeropoints at a low potential or voltage and then rises quickly or sharply to its maximum and immediately falls back to the zero-line and then continues for the balance of the pulse at a low potential or voltage until the next zero-point is reached, Whereas the Waves or pulses heretofore employed begin to rise immediately from the zero with more or less abruptness and continues at a high potential or voltage for the major portion of the interval between zero-points, the major portion of the drop of potential taking place at or near the succeeding zero and with more or less abruptness, depending upon the particular form of wave. The latter form of wave may be conveniently described as one having a wide top and a mean of electromotive force which is comparatively large, so that not only is the total amount of energy consumed or applied by each pulse or wave of electromotive force large, but the actual voltage of the circuit as measured by the voltmeter shows a comparatively high effective potential, which might do damage to persons or property. 1

My invention consists, first, in an alternating current dynamo having the polar faces and spaces between the polar faces in this part of the machine which move with relation to one another proportioned,as hereinafter described, and specifiedin the claims, to produce an improved form of eleotromotive force which, as hereinbefore stated, may conveniently be described as a peaked form.

My invention consists, further, in the special form of dynamo-electric machine especially adapted to produce such a peaked form of wave While at the same time preserving that characteristic of the machine described in my prior patent, No. 644,995, which consists in preserving the constancy of the magnetic fiuX in the magnetic circuit of the machine.

My invention consists, also, of other features of construction and proporti'oning of the polar faces and spaces in the rotary and fixed members of the machine, as will be hereinafter more particularly described and then specified in the claims.

In the accompanying drawings, Figure 1 shows, diagrammatically and in approximately accurate form, one of the kinds of Wave of electromotive forcev heretofore employed,said Waves being shown as alternating, although they might be modified, so as to be all of the same sign or polarity. Fig. 2 illustrates, diagrammatically, one of the shapes of the wave of electromotive force which may be produced by a machine constructed in accordance with my present invention. Fig. 3 illustrates the form and proportion of related, fixed, andmovable poles in a machine adapted to produce the form of wave illustrated in Fig. 1; and Fig. 4 shows the relation and the proportion of the stator and rotor or fixed and movable poles of an improved machine devised by me for the purpose of generating the form of alternating electromotive-force Wave illustrated in Fig. 2. Fig. 5 is a front elevaof the same.

tion of the iron channel-ring or annulus used for the field of the machine illustrated in Fig. 5. Fig.8 shows a form of vacuum-tube lamp adapted for use in my improved system of lighting. Fig. 9 illustrates in side elevation a form which the dynamo may take when it is desired to operate the same by an ordinary electric motor, thus making a self-contained motor and dynamo adapted to be attached to any power-circuit and to furnish a suitable excitation for the vacuum tube. Figs. 10 and 11 illustrate in side elevation and in vertical cross-section a modification in the form of the dynamo-machine.

Referring to Fig. 1, the pole-faces of the cores for the generating-coils in a dynamoinachine adapted to produce the form of electromotive-force wave illustrated are indicated by the numeral 2. The relation of the width of these pole-faces to the space between the poles,as will be seen, is approximately equal that is, the spaces are equal to the width of the pole-faces-and if. said poles or polar projections be wound with a suitable winding passing in reverse direction around said poles or projections alternately and be subjected to the action of a rotating field having polar projections of substantially the form and proportion illustrated in Fig. 3 an alternating eleetromotive force of approximately the form indicated in Fig. 1 would be developed. As will be seen, the top of each wave or pulse is comparatively wide, and this would also be the case with any sine-wave form of alternating electromotive force-that is to say, the wave would continue at a high mean of electromotive force for a large proportion of the interval between the zero-points. The particular wave form shown approaches,however, more closely the square-topped form described in my prior patent, No. 646,858.

The improved form of wave heretofore designated as the peaked form and illustrated in Fig. 2 may be obtained by a modification in the relative widths of the pole-faces on the polar projections 2 as compared with the width of the space between them, this modification consisting, substantially, in widening the intervening space and shortening the poleface in the direction of the movement of the armature-pole, so that the slot or space will be wider than the pole-face. This disproportion of slot and pole-face is shown as carried out to the extent of making the relation of space and face approximately eight to one to produce the particular pointedness or peakedness of wave shown. It will be understood that a less disproportion might exist, with of course a corresponding departure from the characteristic of the improved wave, as already described. I contemplate in practice, however, a' still larger proportion of slot to tooth, thus giving the wave a still more pointed or peaked form and securing in a higher degree the results aimed at. It will be observed that this form of wave possesses in high degree the characteristic of a high rate of change in its increasing and also in its diminishing potential or voltage. This form or character of wave possesses also the further advantage that the actual voltage on the circuit-wires supplied by the machine as measured by a voltmeter continually connected to the circuit-wires and which would indicate the eifective and destructive voltage under ordinary conditions is less than with that form shown in Fig. 1, although the maximum electromotive force of each wave shown in Fig. 2 is greater than that of Fig. 1. \Vhile, therefore, the form of Fig. 2 is better adapted to excite vacuum-tubes or electric lamps of similar character to luminosity because of the higher electromotive force of each wave and because to some extent of its higher rate of change or higher bombarding action, it is less liable to do damage in actual use when the dynamo is made to develop the electromotive force of a voltage and frequency best suited to the purposes of the system. This difference in voltage or potential of the circuit arising from the difference in the form of wave is indicated in Figs. 1 and 2. Thus, for instance, the wave of the Fig. 1 form might with a given frequency give a voltmeter reading on the circuit the same as that indicated by the horizontal line 50, while that given on the circuit by the form of wave shown in Fig. 2 would show a lesser voltage on the circuit, even as low proportionately as that indicated by the horizontal line 51, although the actual electromotive force of each pulse as obtained or observed by plotting through the momentary contact method would show in the case of the wave of Fig. 2 a much higher electromotive force for each individual wave pulse.

The form shown in Fig. 2 may be generated by a dynamo whose field and armature teeth are related or proportioned as indicated in Fig. 4. The polar projections or teeth 2 project from a suitable magnet and are wound, as well understood in the art, with a coil whose direction is reversed on said poles alternately. The field or rotor portion of the machine has polar teeth or projections 3, all of like polarity, which pass said polar pro jections 2 in rapid rotation and produce the varying magnetic flux in the projections 2, that serves to set up alternating electrometive forces. Said projections may be in a magnetic circuit generated or maintained by a suitable field-coil wound on a mass of iron Whose magnetic circuit finds its way through the said poles in any well-known way-as, for instance, in the manner described in my prior patent,No.6t4,995. As willbe seen,the length of the polar projections 3 as compared to the distances from pole to pole 2 is such as to preserve a constant magnetic flux, since as the polar projection of the armature uncovers one pole 2 it covers in the same degree the next succeeding pole of the dynamo.

Referring to Figs. 1, 5, and 6, the details of the dynamo-generator are more fully illus- ICC trated. The field-magnet of the machine is indicated by the numeral 4:. Said field-magnet may consist of an annulus of any magnetic material having one face hollow or recessed to receive the exciting-coil 6, furnished with constant current from any source. The edges of the annulus constitute the two poles of the field-magnet. The toothed pole-face at one edge whereby the several poles are formed may conveniently be constructed by attaching to one edge of the annulus a laminated toothed ring formed of anumber of sheets of metal superposed upon one another and bolted or secured to the edge of the ring, as shown. Between said laminated ring and the opposite edge of the annulus the mass of iron having the polar projections 3 is caused to rotate to produce the varying magnetic flux in the projections 2. The field-magnet 4 is preferably mounted or supported on a base 7, which carries the standards in which are mounted the bearings for the shaft 8. Said shaft carries a disk of steel or other suitable mat-erial,constituting a spider or support 9, to whose edge is bolted the ring which has the polar projections 3. Said rotor consists, preferably, of a number of sheets of iron toothed at their edge to form the polar projections 3 and superimposed and bolted in any suitable manner to the edge of the disk or frame 9. The frame 9 may consist of a thin disk of sheet-steel clamped upon the shaft, as shown. When rotated at high speeds, it will maintain its form and rigidity through the action of the centrifugal forces generated. The form and construction of the field and armature and the manner of mounting and rotating the rotatable parts may obviously be varied without departing from the invention.

In Fig. 8 I have shown one of the lamps heretofore employed by meand to which the form of alternating electromotive forces indicated in Fig. 2 may be applied for the purpose of exciting said lamp to luminosity. Said lamp is of the general form hereto-fore used by me and comprises a tube of glass elongated and of preferably uniform crosssection and containing a rarefied gas, such as air, rarefied to the degree best suited for producing luminosity, as well understood in the art. The tube is provided at its ends with suitable conducting-caps, to which the circuit-wires charged with the alternating electromotive forces are connected.

By the use of myimproved form of dynamomachine herein described for exciting vacunm-tube lamps or similar lamps to luminosity I secure these improved results, namely: I am enabled to employ a low mean voltage of impressed electromotive force, and in this respect am enabled to make a very wide departure from the practice of other inventors, who have always considered it necessary to employ exceedingly high voltages. I also am enabled to excite the tubes to luminosity by comparatively low frequencies of impressed electromotive force and with a minimum of total energy. I also secure not only increased life in the lamp, since the total electrolytic actions produced in the same are largely 10wered, but I am also enabled to develop the electromotive forces required from a dynamomachine without resorting to excessively high speeds or excessively small subdivision of armature and field poles-troubles which are necessarily associated with high frequency. In fact, I have already been enabled to use voltages as low as one thousand volts and frequencies as low as fifty thousand periods per minute and to get therefrom very high degrees of illumination; but an even less voltage and frequency might be employed.

Fig. 9 shows my improved form of machine as mounted for operation by any ordinary type of electric motor, so that by simply attaching the motor to any electric-power-supply circuit the form of energy best suited to the operation of vacuum-tubes may be easily and conveniently obtained. As shown in the figure, 15 indicates an electric motor, to one end of which are bolted the arms 16, supporting the field annulus or ring 1, while the disk or spider 9, which carries the rotary member of the machine, is fastened directly to the shaft of the motor 15, as clearly shown in the drawing. The motor itself may be mounted upon a suitable standard or frame 17.

In the construction of the dynamo, when used for vacuum-tube lighting, very close attention should be paid to so proportioning or organizing the coils and magnetic parts of the same as to develop the alternating electromotive forces with a minimum of self-induc tion, the less the objectionable striations which tend to form in the luminous tubes of a vacuum-tube lighting system. The necessary volts must be generated from the right number of total turns surrounding the right quantity of iron. For example, striations will immediately appear if the volts are generated from too few turns and too much iron, or vice versa.

WhileI have described my invention as applied to vacuum-tubes, I do not wish to be understood as limiting myself to lamps of that special form, but contemplate the use of the invention with any form of lamp adapted to be excited to luminosity by electric waves or vibrations of the general character heretofore used for vacuum-lamps.

Figs. 10 and 11 illustrate a further modification in the construction of the dynamo. The object is to secure a simple and cheap mechanical construction and to permit the machine to be run with minimum heating in the iron portions thereof,through which there is a varying magnetic flux. The form of machine illustrated in these figures is, like the form shown in the previous figures, adapted to produce a plusating electromotive force of the wave form already described as peaked. Fig. 10 is a side elevation showing the proportionate lengths of the polar projections or &

teeth in the fixed and rotary portions of the machine, and Fig. 11 is a vertical cross-section through a portion of the machine.

In the improved form of machine shown in Figs. and 11 the varying magnetic flux has its path through soft iron made of a laminated mass constructed from sheet-iron or other proper form of iron, whereas in the form previously described the magnetic flux is partially through a cast-iron annulus or ring. The polar projections 2 are formed, as before, at the inner edge of a laminated toothed ring, (seen more clearly in Fig. 11,) said laminated toothed ring being properly clamped in a frame 25,0'f cast-iron or any other suitable material. The polar projections 3 of the rotating member,which serves to produce the varying magnetic flux in the projections 2,carrying the generator-coi1s of the machine, are differently proportioned from those shown in the previous figures; but the distance between the polar projections 2 is, as already explained, greater than the length of the polar faces measured in the direction of the rotating member. Assuming that the rotation is in the direction of the arrow 30, the polar projections, as shown, are of sufficient length to cover not only two adjacent polefaces 2 and the space between them, but overlap the adjoining space-a distance which may be stated as extending from the edge of one of the stator-teeth 2, backward toward the front edge of the nearest tooth one-half the distance of the space between said teeth minus one-halt the width of a stator-tooth.

The exciter-coils of the machine are properly connected or operated to cause the polar projections 2 to exhibit alternate north and south poles, and the rotor-teeth 3 in bridging adjacent poles act as an armature for completing the magnetic circuit between said adjacent poles. The general path of the magnetic flux for each magnetic circuit thus closed is indicated by the dotted lines at iO in Fig. 10.

The exciting-coils may be wound directly upon the teeth or projections 2 or, as indicated at 41, may be wound around the annulus or ring from which said teeth 2 project. The windings 41 would be repeated and supplied or fed with exciting-current in such way as to produce consequent poles in the projections 2, which would be, as already described, alternately north and south proceeding circumferentially. The generator-coils applied upon the polar teeth 2 would be connected up reversely in series, so that the electromotive forces excited in them would conspire. As will be seen, there is no varying magnetic flux in this form of machine in the cast-iron frame 25, but said flux is entirely through the soft-iron laminated annulus from which the teeth 2 project and through the laminated iron mass of which the projections 3 in the rotor are formed.

In the drawings I have shown the stator as furnished with eight projections 2 and the rotor as furnished with four of the projections 3. With this form and proportion of rotor and stator teeth a pulsation of electromotive force will be produced, as four of the stator-teeth have their pole-faces covered by the rotor-teeth 3, and another pulse will be produced as the alternate teeth 2 next behind those covered are uncovered by the statorteeth. By the proportioning of the teeth shown a regular succession of pulses, positive and negative, is obtained, and in one revolution of the machine eight positive and eight negative pulses or eight whole waves or periods of electr'om otive force would be produced. To secure the same number of waves in a whole revolution of the machine by the arran gement shown in Fig. 4, would require twice as many stator-teeth and twice as many rotor-teeth as are used with the arrangement shown in Fig. 10. The arrangement or construction of Fig. 10 has therefore the distinct advantage that it may have a low self-induction, because less iron will be required to produce the required electromotive force, owing to the fact that with the same number of turns in the generating-coils but one-half the total number of teeth in the rotor and stator is required. The form shown in Fig. 10 also possesses the advantage already stat-ed, that as there is no varying magnetic flux in the cast-iron portions of the machine, but said ilux takes place wholly in soft iron, the said machine can be designed readily, so that it can be run cool.

What I claim as my invention is- 1. An alternating-current dynamo having the spaces between polar projections in one of its elements widened to exceed the length of the pole'faees in the direction of revolution of the machine as and for the purpose described.

2. An alternatingcurrent dynamo com prising fixed and rotary members as described, one carrying the generator-coils and excitercoils adapted to excite the poles thereof so that they will be alternately north and south, and the other having polar projections adapted to bridge the spaces between the former said projections being proportioned with re lation to one another and to the space between poles in the manner described so as to produce a series of pulses graphically represented as of peaked form.

In an alternating-current dynamo, the combination of fixed and rotary members as described, one carrying the generator-coils and exciter-coils adapted to excite the poles thereof so that they will be alternately north and south, and the other having polar projections adapted to bridge the spaces between the former said projections being proportioned with relation to one another and to the space between poles in the manner described so as to produce a series of pulses graphically rep resented as of peaked form.

i. In a dynamo electric machine the combination substantially as described of a fieldmagnet provided with polar teeth the spaces between which exceed the length of the polefaces in the direction of rotation, generatingcoils wound on said polar projections and a rotatable element having polar projections adapted to bridge the spaces between the teeth bearing the generating-coils in the manner described so as to keep the total magnetic flux of the machine constant while varying the fiuX in the individual generating-coils.

5. In an alternating-current dynamo a field magnet consisting as described of an annulus having a recess at one side and provided with an exciting-coil within said recess in combination with a laminated ring adapted to be rotated in the space between the poles of said annulus, said ring having polar projections adapted to bridge the spaces between poles of the annulus and the spaces between the poles of the latter being widened to exceed the length of the pole-faces in their direction of revolution of the machine, as and for the purpose described.

6. In an alternating-current dynamo, the combination with a field-magnet consisting of an annulus having a recess in one face, of a toothed annulus of laminated iron secured to the edge of a disk or spider and rotated by any suitable power in the space between the edges of the annulus constituting the fieldmagnet, said toothed annulus having polar projections adapted to bridge the spaces between poles of the annulus and the spaces between the poles of the latter being widened to exceed the length of the pole-faces in the direction of revolution of the machine.

7. In an alternating-current dynamo the combination with an annulus having a recess in one side, of an exciting-coil located in said recess, a toothed laminated ring secured to one polar edge of the annulus and a rotatable toothed ring adapted to rotate in the space between the two edges of the annulus provided with the exciting-coil, said toothed ring having polar projections adapted to bridge the spaces between the poles of the laminated ring secured to one polar edge of the annulus I and the spaces between the polar projections of the latter laminated ring being widened to exceed the length of the pole-faces in the direction of revolution of the machine.

Signed at New York city, in the county of New York and State of New York, this 9th day of April, A. D. 1901;

DANIEL MCFARLAN MOORE.

Witnesses:

DELBERT I-I. DECKER, ETHEL L. LAWLER.

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