US508489A - Chaeles f - Google Patents

Description

(1I 0 Model.) O. P. SCOTT.

DEVICE FOR INDIGATING SYNGHRONISM.

Patented Nov. 14, 1893.

UNITED STATES PATENT @Fricn.

CHARLES F. SCOTT, OF PITTSBURG, IENNSYLVANIA,-ASSIGNOR TO THE WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, OF

SAME PLACE.

DEVICE FOR INDIQATING SYNCHRONISM.

SPECIFICATION forming part of Letters Patent No. 508,489, dated November 14, 1893.

Application filed September 28, 1892. 'Serial N9.44=7,l42. (No model.)

To all whom it may concern.

Be it known that 1, CHARLES F. Soorr, a citizen of the United States, residing in Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Intermittent Electro- Magnetic Motors, (Case No. 512,) of which the following is a specification.

My invention relates to means for cont-rolling any device the operation of which is intimately related as to time or otherwise with the variations in speed of a commutator adapted to revolve in or out of synchronism with an alternating current fed thereto.

In various kinds'of alternating current ap paratus commutators are employed, the full effect of which is only useful when they have been brought into synchronism; or, in other words, when their speed is such as to make commutator reversals synchronous with reversals in the alternating current fed thereto. A familiar example is found in the ordinary alternating current motor, where, until the motor-and consequently the commutatoris brought up to synchronism, the full load cannot be applied. Here the time of throwing on the load is dependent upon the occurrence of synchronism; but multitudes of other cases will readily occur to those skilled in the art, wherein some mechanical movement or operation should be timed by the occurrence of synchronism. As this occurence is not of a nature to conspicuously proclaim itself to the observer, it is desirable that some form of mechanism be devised whereby it may be indicated, or'whereby such operations as are dependent upon the occurrence of synchronism may be automatically carried out by reason of such occu'rrenceitself. Such a device it is which forms the object of my present invention, the essential feature of which is an intermittent electro-magnetic' motor dependent for action upon the occurrence of synchronism movement in any desired form of commutator, rotating or otherwise moving, to which an alternating current is fed, and designed to indicate such occurrence or to perform automatically such operations as it may be necessary to have timed with relation to such occurrence.

In the accompanying drawings Figures 1, 2 and 3 are diagrams of sine waves of current fully commutated, uncommutated and partly commutated, respectively. Fig. 4 is a diagram illustrative of my invention as applied to such currents, and Fig. 5 is a detail view of a modification.

In Fig. 4, 1 and 2 are two solid magnetic parts, which I shall, for convenience, call primary and secondary armatures, inasmuch as either part may be made to move with relation to the other which is fixed. At 3 is shown a commutator which may be of any form, rotating or otherwise moving, whereby.

currents may be reversed in direction in any 6 of the conductors connected therewith. This commutator is shown in two parts; but any number of parts desired may, of course, be employed. It is to be understood that this commutator is connected electricallyand mechanically with any alternating current device the synchronous movement of which is to control the action of my intermittent motor. In Fig. 5 I have shown one form of an indicating device whereby the occurrence of synchronism may be indicated by the movement of a finger on a dial. The operation of this arrangement of parts will be immediately obvious to one skilled in the art. Permanently connected with this commutator in sucha manner as to receive the same alter nations'as are sent tojthe indicating or governing device itself is a primary coil at surrounding the primary core 1, or otherwise placed in magnetizing relation thereto. The alternating current to be commutated is supplied from any convenient source, indicated typically at 5. Around the secondary armature 2 is wound a secondary coil 6, closed upon itself as shown. The actions going on in the two armatures will be best understood I by a discussion of Figs. 1,2 and 3.

In Fig. 2 is shown the usual sine wave employed as typical of alternating currents as usually generated. Five half waves are illus- 95 trated. Fig. I shows the pulsating current resulting from commutation in synchronism wherein every second wave in Fig. '2'is'in verted and changed from negative to positive. 1 Upon passlng an alternating current, such as too is shown in full lines in Fig. 2, through the coil 4, the core 1, being solid and therefore sluggish, the magnetic eifect in said core would be such as indicated by the dotted wave in Fig. 2. The flattening of this wave may be emphasized to almost any extent by properly proportioning the core to the arm pere turns of the coil upon it. The secondary core 2, being virtually a continuation of the magnet 1, will receive magnetization indicated by a wave of the same general character; but, as shown, the magnetization of both armatures will be very small. The coil 6 will have secondary currents generated in it by the magnetization of the core 2, which currents will tend to cut down said magnetization and thus further neutralize the attraction between the armatures. Another effect of the currents in the coil 6 is to so increase the magnetic resistance in the core 2 as to cause the lines of force emanating from the core 1, which would otherwise traverse the core 2, to seek a path of less resistance through the air, as indicated in dotted lines in Fig. 4. Lastly, the currents in the coil 6 being contrary in direction to those in the coil 4, there will be a repulsion between the two coils which will serve to complete the neutralizing of any possible attraction between the cores 1 and 2, and even, if desired, produce a predominance of repulsion. It is, therefore, evident that with uncommutated currents all the causes above detailed will conspire to produce repulsion rather than attraction between the armatures 1 and 2.

Upon consideration of the conditions existing where the commutator revolves with an accelerated speed, approaching synchronism, it will be found that the same absence of attraction between the armatures continues. The curves in Fig. 3 show the current conditions in the coil 4, when the speed of a commutator is such as to cause reversals of five-eighths of a wave length apart. In this case the regular progress of the wave is interrupted at each reversal of the commutator, and the curve is inverted.

The curves in Fig. 3 are produced from those in Fig. 2 by inverting alternate portions of said curves as divided by the dotted lines A, 13,0, which indicate points of reversal of the commutator.

Upon inspection of Fig. 3 it will be seen that although the commutator is running quite close to synchronism in the five halt waves illustrated, there is quite as large a proportion of negative magnetizing effect as of positive, and the effect upon the armature 1 of the passage of such currents will be similar to that of the current shown in Fig. 2. indeed, if we consider the successive fractions of waves a, b, c and cl, we shall see that they representpositive impulses during four-fifths, three-fifths, two-fifths and one-fifth of their durations respectively. The average effect of each wave fraction is represented by the difference between the areas inclosed between the successive curves and the line of zero current above and below said line. In the wave fraction (1, for instance, the area between the curved line and the line of zero is greater above the line than below it. If we take the difference between these areas and plot a point a at a distance above the line of zero representing such difference, and if this operation is repeated for each wave fraction, and the points so plotted be connected by a dotted line, as shown in Fig. 3, a wave of resultant eifect will be produced which will serve to show the alternating character of the magnetic effect produced by the irregular currents which exist just before the commutator reaches synchronism. It is thus made clear that the magnetic equivalent of a slow alternating current approximately corresponding to the dotted line in Fig. 3 will circulate in the coil 4 and it is therefore evident that the magnetic relations detailed above in connection with Fig. 2 will persist to some extent as long as the commutator is out of synchronism. It is thus seen that however close the commutator may come to synchronism without reaching it, the armatures 1 and 2 remain negative. As soon, however, as synchronism is actually reached, the conditions in the device shown in Fig. 4: are totally changed. The current will vary as shown in Fig. 1 and the armature 1 being sluggish, will immediately assume a nearly constant magnetization corresponding to the dotted line shown in Fig. 1. The variations in this line being very small there will be very little secondary current in the coil 6 and consequently practically no opposition to the uniform magnetization of the armature 2 and practically no repulsion between the coils 4 and 6. The considerable magnetization of the two armatures thus permitted under the new conditions unbalanced by coil repulsion, will cause a strong and sudden attraction between the armatures which will then constitute a momentary motor by proper mechani- IIO cal connection with which any desired automatic mechanism may be operated.

As above stated, the primary coil 4 need not necessarily be placed in relation to the core 1 as shown in Fig. 4 as long as its condition is such that it will act to magnetize said core. The same may be said of the coil 6, and its relation to the core 2. Said coil may be fixed to the core 2, or said core may move freely within it, and the fixed or movable relation of coil to core may also obtain in the primary armature.

In Fig. 5 Ihave shown a modification wherein the primary and secondary coils are mounted upon the same core and said core is made to attract the soft iron armature 7 when synchronism of thecommutator has been reached.

The considerations above detailed will apply to Fig. 5, which therefore needs no further description.

In one of the following claims I have called tion.

for a practically. solidarmature in combina- The object of using a solid armature is to produce sluggishness in the changes of magnetization therein. The term solid is used here in contradistinction to the word laminated and it is not desired to have the word'understood in that strict sense which would enable aninfringer-to make the armature in two or three parts without practically afiecting the sluggishness of the core. The Words practically solic therefore have reference to solidity in its relation to slowness of the magnetic changes in the core.

What I claim is 1. A source of alternating electric currents,

and a commutator connected therewith adapt-- ed to cause reversals of various frequencies; incombination with primary and secondary armatures, a coilconnected .to said commutator,in magnetizing relation to said primary armature,'and a secondary coil adapted to be inductivelyaffected by changes in the magnetismvof said primary armature,.substantiallyas described.

2. A source of alternating electric currents, and acommutator connected therewith, adapted to cause reversals of variouslfrequencies; in combination with primary and secondary armatures, a primary coil connected to said primary-armature, and a secondary coil in magnetizing relation to said secondary armature, said secondary armature being located ondary armatures, a primary coil connected to saidcommutator, in magnetizingrelation to said primary armature, and a secondary coil in magnetizing relation to said secondary armature, saidsecondary armature being located within the-magnetic field of said primary armature, and one of said coils being movable with its own armature, substantially as described.

4.. A source of alternating electric currents, and a commutatorconnected therewith, adapted to cause reversalsof various frequencies; in combination with a practically solid primary armature, and a primary magnetizing core therefor, connected with said commutator, and a practically solid secondary armature in the field of forceof said primary armature, and a secondary coil closed on itself wound thereon and movable therewith, substantially as described.

In testimony whereof I have hereunto sub scribed my name.

CHAS. F. SCOTT.

' Witnesses: JAMES WM. SMITH, HAROLD S. MAOKAYE.

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