US426348A - Necticut - Google Patents

Description

(No Model.) 5 Sheets-Sheet l.

M. J. WIGHTMAN & E. THOMSON DYNAMO ELECTRIC MACHINE.

N0..426,848. Patented Apr. 22, 1890.

w J mmm (No Model.) 5 SheetsSheet 2.

M. J. WIGHTMAN & E. THOMSON. DYNAMO ELECTRIC MACHINE.

N0. 426,348. Patented Apr. 22, 1890.

L. w It we wl (No Model.) 5 Sheets-Sheet 3.

M. J. WIGHTMAN & E. THOMSON;

DYNAMO ELECTRIC MACHINE.

Patented Apr. 22

(No Model.) 5 SheetS Sheet 4.

M. WIGHTMAN & E. THOMSON.

DYNAMO ELECTRIC MAGHINB.

Patented Apr. 22,

- Q/qhtwaooaa (No Model.)

M. J. WIGHTMAN & E. THOMSON.

DYNAMO ELECTRIC MACHINE.

5 SheetsSheet 5.

Patented Apr. 22, 1890.

UNITED STATES PATENT OFFICE.

MERLE J. WVIGHTMAN AND ELIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNORS TO THE THOMSON-HOUSTON ELECTRIC COMPANY, OF CON- NECTICUT.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 426,348, dated April 22, 1890.

Application filed September 17, 1888. Serial No. 285,584. (No model.)

To all whom it may concern:

Be it known that we, MERLE J. WIGHTMAN and ELIHU THOMSON, citizens of the United States, residing at Lynn, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Magneto-Electric Machines, of which the following is such a full, clear, and exact description as will enable any one skilled in the art to which it appertains to make and usethe same, reference being had to the accompanying drawings, forming part of this specification.

Our invention relates more especially to self-exciting multipolar alternating dynamos, and it also relates to improvements in dynamo-electric machines generally. I

The principal objects of the invention are to produce in a multipolar dynamo of the character indicated an arrangement of coils and method of commutating the same that will give the least amount of fluctuation in the external circuit and to prevent sparking at the brushes upon change of load.

The invention consists, first, in a new and useful combined core and winding for dynamo-electric machines, more especially for.

' armatures; second, in modifications of this;

third, in a new and useful arrangement of circuits, whereby the alternating current is commutated to excite the field-magnets or to generate a continuous current for supplying a workingcircuit; fourth, the combination of the latter with the new form of armature or combined core and winding; fifth, to provide means whereby the continuous or selfexciting current generated is modified, so as to make any change in the current strength flowing in the same more gradual, so that the commutator of the dynamo will be less subject to changes in the position of the brushes than heretofore; sixth, in a modification of the latter; seventh, in providing means for adjusting the brushes of the commutator, so that all external resistances may be dispensed with in regulating the machine, and, eighth, in details of construction, now to be set forth, and in other features, which will be described at length.

The novel features of the foregoing will be particularly pointed out in the claims making a part hereof.

other arrangement of our invention.

I11 the accompanying drawings, Figure 1 is an end view of an armature of a magneto-electric machine made in accordance with our invention, a part of the same being broken away to show the coils more clearly. Fig. 2 is a side view of the foregoing with a part of the armature broken away, as before. Fig. 3 shows a plan View of a modification of the fore going. Fig. 1 is an end View of a still further modified way of constructing an armature for self exciting alternating dynamos, the same showing how the exciting-coils may be applied to an alternating machine as now constructed. Fig. 5 is a plan view of a portion of an armature, showing another way of winding the excitingcoils, which does not necessitate any change in the armatures of dynamo machines as usually constructed. Fig. 6 is an end view of one form of dynamo made in accordance with our invention, showing a diagram of the circuits and our way of commutating the current. Fig. 7 shows a11- Figs. 8, 9, and 10 are diagrammatic views of the currents generated. Fig. 11 is an end view of adynamo provided with means for modifying the current to render it less sensitive to changes in the adjustment of the brushes. Fig. 12 is an end view of a dynamo partially wound.

corresponding to Fig. 11, showing a modified form of means for modifyingthe current generated in the exciting-coils. Fig.13is an end view of a means for adjusting the brushes on the commutator in accordance with-our i11- vention.

The same figures of reference indicate the same or corresponding parts throughout the various views.

Having now more particular reference to Figs. 1 and 2,15 isashaft, uponwhich is preferably arranged a spider 1.6, that supports the armature-core upon which the coils are located. The core is preferably made up of plates or laminae 17, as usual, which are fastened together by bolts 18. Around the coreat any suitable distance apart are wound coils 19, which are the exciting-coils. The coils 19 preferably do not extend to the full length of the armature, but pass through spaces 20 left between the laminae of the core near each end of the armature, the spaces 20 serving also to aflord ventilation for the armature. Around the exciting-coils 19- preferably on the exterior of the armature are wound the alternating coils 21. These altern'ating coils are independent coils and are suitably connected together, so as to place said coils in series, as usual, and may be in electrical connection with a current-gatherer as ordinarily used in alternating machines. These features are not shown, in order to avoid confusion and because they make no part of the present invention. Between the alternating coils may be placed strips of wood 22 or other insulating material. Bands 23 and 24 are then placed about the armature to secure the foregoing to said armature.

In Fig. 3 a modified way of winding the alternating coils is shown. The exciting-coils 19 and the interior of the armature are arranged as described above. The alternating coils, however, are wound continuously around the armature in a sinuous curve, making, in fact, one coil around the armature with a multiplicity of windings, as clearly shown in Fig. 3. The alternating coils are preferably composed of ribbons of sheet-iron or any other magnetic metal instead of wire. The crosssection of the iron ribbons can be made of such area as to render the conductivity of the ribbons the same as that of the ordinary copperwire used on armatures. The iron ribbon can be made three-quarters of an inch broad and three one-hundredths of an inch thick, which will equal the resistance of a No. 12 copper wire. We do not, of course, confine ourselves to any particular dimensions. The coils of ribbon are suitably insulated from each other. These features will be evident from an inspection of Figs. 1 and 2. It will be noted by this arrangement that the alternating coils constitute the pole-pieces or cores, as well as coils or windings. It will be noted, further, that by this means the core of the armature can be in fact brought nearer to the pole-pieces of the field-magnets, so as to increase the efficiency of dynamomachines. This produces, in fact, an armature of the Pacinotti type. The alternating coils are arranged upon the exterior of the armature only, so that there is no dead resistance in said coils.

So far as we are aware, we do not believe a combined core and winding has ever been used heretofore in any class of electrical machines.

In Fig. 4 is shown a way of applying the exciting coils to any alternating current dynamo, the core being cut away between the alternating coils 21, and the exciting-coils 19 being wound around the core in the cut-away places, as clearly shown in said figure. 22 is a strip of wood or other insulating material between the alternating coils, as previously described.

In Fi 5 is shown a still further modification, in which the armature-core does not have to be cut away to apply the exciting-coils to the armature. The regular alternating coils are represented by 21, as before, and one of the exciting-coils is represented by 19 and another by 19. The ends of these excitingcoils are then carried to the commutator, as clearly shown in Figs. 6 and 7, just like the exciting coils previously described. The coil 19 is threaded, so to speak, up through the spaces between one of the alternating coils, down on the other side of the armature,

up through the internal space of the next coil,

down the side of the armature, and up through the internal space of the third alternating coil, and then up through the internal space of the fourth alternating coil. Its two ends are then connected to the commutator. The coil 19' is wound zigzag, or in a sinuous line, between the alternating coils, and its ends are led to the commutator.

Fig. 5 represents but a small part of an armature and shows but a few coils. The exciting- coils 19 and 19 correspond to two adjacent coils shown in the other figures. Another section of the armature would be wound in the same manner and the excitingcoils connected to the commutator until all the alternating coils around the armature had been threaded with exciting-coils. In the drawings we have shown but one turn of wire threaded through and between the alternating coils; but of course in practice more than one layer of wire could be threaded between said coils.

Fig. 6 shows the organization of circuits and means for coupling an open-circuit selfexciting alternating machine. 19 are the excitingcoils, and 21 the alternating coils, made in accordance with our invention. 25 are the pole-pieces. 26 is the commutator upon which the brushes 27 and 28 hear. The

number of pole-pieces can be increased 'indefinitely, and also the number of coils to correspond thereto. The number of commutator-strips is always double the number of poles, or equal to the number of excitingcoils. The current-gatherer for the alternating coils is not shown, in order to prevent confusion and because the same forms no part of the present invention and is well known The exciting-coils are preferably arranged to be coupled in multiple are, but could be constructed to be coupled in series. The opposite segments of the commutator are preferably connected together, and the adjacent ends of every other exciting-coil are connected with the same commutator-strip all around the armature, as clearly shown in Fig. 6. The current-collector may consist of two sets of brushes preferably removed from each other by one segment of the commutator. These brushes are connected with the fieldmagnet coils, and may also supply current to a working-circuit 29, having incandescent lamps or other translating devices arranged therein.

The arrows in Fig. 6 show the direction the current passes when the armature is in the rro' position shown. Under this state of affairs the coils 19, midway between the pole-pieces, are open-circuited, and the coils 19 at the polepieces (in the most intense part of the field) are all supplying the working and exciting circuit in multiple arc. lVhen the armature rotates still farther and brings the brushes 27 and 28 upon adjacent segments of the com- Inutator, and the pole-pieces are midway between the coils 19, all of the coils 19 will be in circuit in multiple are. As the armature progresses and the brushes leave the commutator-strip upon which they previously rested and bear upon the nextcommutator-strip, the coils 19, that in the first instance were generatin g alone, are now midway between the polepieces and will be cut out of circuit, and the coils 19, which were previously cut out of circuit, will be generating, and so on. Thus those coils which are midway between the poles and out of the magnetic field are always out out of circuit and the dead-armature resistance is removed from the circuit. The general principle of the invention is to cut in generating-coils before or just previous to the cutting out of others. The arrangement of circuits and electrical connections could of course be used with any kind of alternating coils.

In Fig. 7 the alternating coils 21 are shown as those of the ordinary type. The arrangement therein is that known as the Thomson- Houston coupling. It can be made with any number of poles and coils and can be coupled in series or in multiple arc. The rule to be followed in coupling with any number of poles is: Distance between coils should be twothirds distance between poles and number of 3n commutator-strips, equal to where n 1s the number of poles. I11 this arrangement the opposite segments of the commutator are connected together as before and the three coils in the upper half of the diagram have one end connected to their respective commutator-strip and their other ends joined together, as shown in the drawings. The three coils in the lower half of the diagram are coupled in the same manner, and the brushes 27 and 28 are arranged as before described. In this way two of the coils are always in multiple and one of said coils in series with the two in multiple. The coils farthest removed from the pole in each set of three coils (that is to say, which is in a weak part of the field) are in multiple, while the coil at the pole-piece (in the strongest part of the field) is in series with the others. All of the coils in this arrangement are always in circuit, and the coils put in multiple correspond to those which in the previous instance were cut out of circuit. When the armature rotates farther, so as to change the relation of the parts shown, the same operation is performed-that is, those coils are put in multiple which are the farthest from the field and the one in the most intense part of the field is put in series with the others. In this instance the exciting-coils are only used to generate current for the fieldmagnets and do not supply a working-circuit in addition thereto.

To illustrate the dilference between currents generated by a machine constructed in accordance with this invention and the ordinary type, we have illustrated the same diagrammatically in Figs. 3, 9, and 10. The coils in an ordinary alternating dynamo would produce a current which would be represented by the curved line 30 in Fig. 8, in which 0 represents the zero-line. In order to get a continuous current from this, a commutator is used which reverses that part of the current below the zero-line. Such commutation of the current would be represented by the curved dotted line 31. By this arrangement all fluctuations might be considered as taking place upon one side of the neutral or zero linethat is, producing a continuous current or a current flowing in one direction, which would be represented by the curves 30 and 31 above the zero-line. This represents a curve that would ordinarily be generated in the exciting-coils 19, opposite the poles in Figs. 6 and 7.

One feature of this invention is the addition of the extra coils 19, that are shown between the pole-pieces in Fig. 6, which are so situated relatively to the other coils that their current is ml or relatively weaker when the current in the other coils is strongest, and vice versa. The current from these extra coils would be represented by the curved line 32 of Fig. 9, and when this current was com mutated the commutated part would be represented by line The resultant of the two would be represented in Fig. 10 by the lines 30, 32, 31, 33, 30, 32, 31, 33, &c.that is, the current would be flowing in the same direction. It will be seen that there'is a period when some of the coils in Fig. 6 are not in contact with the brushes-that is to say, are cut out of circuit. The period during which the coils are cut out of circuit will be represented by the dotted lines in Fig. 10. The advantage of such an arrangement practically is that it does not require a close adjustment of the brushes on the commutator, as the old form of dynamo, giving a current curve, represented by the line 30 31 of Fig.8. The reason of this is that commutation in the one case, Fig. 8, should. take place at the point 34:, where the difference of potential is zero, and if the brush should be located at a point so as to collectthe current at a point a little to the left of 3-isay 35the tendency of the brush would be to rupture acurrent of the potential represented by the distance of 35 from the zero-line. In Fig. 10 the commutation takes place at the point 36, and if it be assumed that the brush should be misplaced, so as to commutate earlier-say an equal distance to that assumed in the previous case at the point 37-it will be seen that the difference of potential at the point of rupture IOO IIO

37 will be equal to the distance marked 38, and will be considerably less than the distance from the point of rupture 35 to the zeroline in the previous instance. This feature of lack of sensitiveness in the setting of the brushes is of considerable importance in selfexciting alternating-current dynamos, since with a changcof load in the alternating coils the neutral point of the exciting-coils become shifted and unless a resetting of the brushes is made, serious wearing away of the commutator occurs.

Fig. 11 shows adevice for obtaining a modification of the curve which would ordinarily be generated by these exciting-coils. 1t consists in inserting in the circuit of the excitingcoils small reactive or kicking coils 39 89- that is, coils of high self-induction. The addition of the reactive coils in the circuit of these armature-exciting coils tends to make any change in the current strength flowing in the same more gradual. The action of such coils, in other words, is to shape the curve of an alternating current passing through them to more nearly the true sine curve. The rate of change is much less than when the reactive coils are not used, and with such an arrangement the commutator of the dynamo will be less sensitive to changes in the position of the brushes than heretofore.

The effect of self-induction on a regular wave-such as a sine curveis to lag the wave and at the same time cut down its amplitude without affecting greatly the shape of the wave. If, however, the wave be one in which there are abrupt changes of current occurring, the effect of an interposed self-induction is to act most energetically on those points of the wave at which the changes are most abrupt or sudden. The result of this is that the wave, if of an irregular or jumpy character, is practically smoothed out. A wave which has at one point a sudden elevation of potential while the rest of the impulse is more gradual in its change would by selfinduction have the current produced follow ing a wave-line in which the effect of the sudden potential was in a measure obliterated, though not entirely. At the same time the wave would be lagged from its original position and the amplitude or height of the wave as a whole cut down. Self-induction may be said, therefore, to be a storing up of energy on an abrupt change attempting to take place and a giving out of that energy on a sudden tendency to reversal of this action. The irregularities of the Wave do not absolutely disappear; but the irregularities of very great vibration rate or rate of change are the ones which are almost made to disappear by having self-induction in the circuit. \Vhile this is our theory of the practical working of the self-induction coils in the circuit to fulfill the function desired, we do not wish to belimited to this theory. Two reactive coils are used to always have one of them in circuit, as with the open-circuit dynamo, which we have de scribed above, one of said reactive coils would be cut out of circuit when the coils in the circuit therewith were cut out of circuit.

Another and important effect of the reactive coils is to prevent any discharge from one coil through the other while the same are connected in multiple at the commutator. This discharge would be quite considerable, since the potential at the terminals of the coils in multiple would be quite unequal, being in different positions relatively to the field. The reactive coils increase the selfinduction in the circuits of the generatingcoils, therefore hindering any tendency to a sudden discharge or change of current strength in them.

In Fig. 12 the reactive coils are wound upon one core, each coil encircling one-quarter of a ring 43, and connected to a similar coil on the diametrically-opposite part of the core, in order to produce uniform magnetic action in all parts of the core. The elfect of these coils is to produce rotating poles in the magnetized core, and they therefore add self-induction in the circuit of the armature-coils. They make in effect two reactive coils, as before described. These reactive coils can be disposed in any manner desired, it only being necessary that they be in the circuit somewhere, so as to modify the effect of the current passing in said circuit.

Fig. 13 shows a device for adjusting the brushes of the commutator, constructed according to our invention. By having the brushes adjustable with relation to each other it is possible to dispense with all external resistances for regulating the current. In this arrangement the lower brushes of 27 and 28 are attached to a ring it, which is loosely suspended from the armature-shaft 15,and the upper brushes of 27 and 28 are connected to a ring 45, movably swung about the armature-shaft, as before. The rings are independently adjustable around said shaft as a center. To obtain the best regulating effect, a forward movement of the lower brushes of 27 and 28 should be imparted with a backward movement of the upper brushes of 27 and 28. This can be obtained by numerous devices, one of which is shown in Fig. 14, which may consist of two rods 46 and 4:7,connected to a lever 48, which is pivoted to a fulcrum 49 between the rods 45 and 46. A ratchet 50 may also be provided, in which a spring-actuated pawl 5i may take to hold the brushes in position. An automatic adjustment of these brushes according to the difference of potential at any point on the circuit of the dynamo maybe made by methods well known in the art. As was mentioned before, the lead or position of the brushes changes with a change in the load on the dynamo. This change in the lead amounts, in effect, to a shifting of the brushes, and the brushes can be normally so set that this shifting of the lead will produce in the field-exciting circuit enough increase or decrease of current,

ITO

as the case may be, to act in maintaining a variable strength of field, according as the current in the external circuit varies. By this means we obtain the result secured by a compound-wound machine without the usual complication necessary in constructing a compound machine.

Having now fully set forth our invention and described its operation and advantages, we wish to have it understood that we do not limit ourselves to the exact devices and arrangement described, as many changes may be made in the same and still be within the scope of our invention.

WVhat we desire to claim and secure by Letters Patent of the United States as ourinvention is 1. An armature for electric machines, made up of ribbons of magnetic metal suitably insulated from each other, constituting the coils thereof, and arranged upon the periphery of a magnetic core, substantially as set forth.

2. The combination, in a self-exciting alternating-current dynamo, of alternating coils made up of ribbons of magnetic metal suitably insulated from each other, arranged upon the exterior of the armature, and self-exciting coils wound around the core of said armature and between said alternating coils.

The combination, in a self-exciting altern ating-current dynamo, of alternating coils arranged around the armature, self-exciting coils wound between and below the alternating coils in cut-away places in the core, and suitable means for commutating the current from the exciting-coils, substantially as described.

4. The combination, to form an armature of a self-exciting alternating magneto-electric machine, of alternating coils 21,1nade up of ribbons of magnetic metal suitably insulated from each other, exciting-coils l9, wound around the core between the alternating coils and through spaces 20 left in said core, insulating-sticks 22 between the various alternating coils, and bands 23 24, for binding the alternating coils and insulating-sticks to the armature, substantially as described.

5. The combination, to form a self-exciting alternating current magneto electric machine, of alternating coils arranged around the armature, exciting-coils wound around said armature, a suitable commutator therefor, and additional exciting-coils also wound around said armature and connected to commutator in such relation that when the current in the first-mentioned coils is the greatest the current in the extra coils will be the least, and vice versa, substantially as described.

6. The combination, to form a self-exciting alternating-current magneto-electric machine, of' alternating coils arranged around the armature, exciting-coils wound around said armature, a suitable commutator therefor, and additional exciting-coils also wound around said armature, connected to commutator in such relation that when the current in the first-mentioned coils is the greatest the current in the extra coils will be the least, and vice versa, and also so that those coils in which the least current is passing will be cut out of circuit.

7. The combination, to form a self-exciting alternating magneto-electric machine,of alternatin g coils arranged around an armature, exciting-coils wound in the spaces between the parts of each alternating coil, additional exciting-coils arranged between the first-mentioned exciting-coils, a commutator having segments equal to the number of coils and having opposite segments electrically con nected together, the adjacent ends of every other exciting-coil being connected to the same commutator-strip, and brushes suitably distanced apart bearing upon said commutator.

8. The combination, in a magneto-electric machine, of a coil of high self-induction arranged in the circuit to modify the current generated and make changes in the current strength flowing in the armature more gradual, whereby the commutator of the dynamo will be less sensitive to changes in position of the brushes and sparking will also be obviated.

9. The combination, in a self-exciting alternating magneto-electric machine, of one or more coils of high self-induction, arranged in the circuit of the exciting-coils to render more gradual changes in the current generated, whereby the commutator willbeless sensitive to changes in position of the brushes.

10. The combination, in a self-exciting alternating-current magneto-electric machine, of alternating coils and exciting-coils, a commutator for said exciting-coils, two sets of brushes bearing on said commutator, movable supports for said brushes, and connections for shifting said brushes, for the purpose set forth.

11. The combination, in a self-exciting alternating-current magneto-electric machine, of alternating coils and exciting-coils,acommutator for said exciting-coils, two sets of brushes 27 and 2S,bearing on said commutator, amovable support for said brushes, the corresponding brush in each set being mounted upon the same support, and connections for shifting said brushes toward and from each other, substantially as described.

12. The combination, in a self-exciting alternating-current magneto-electric machine, of

alternating coils, exciting-coils, a commutator 26 for said exciting-coils, two sets of brushes 27 and 2S, bearing upon said commutator, the corresponding brush of each set being secured to movable rings 44: and 45, respectively, rods a6 and 47, for controlling said movable rings, and a lever 48, to which said rods are connected, pivoted to a fulcrum between said rods, and controlled in substantially the manner set forth.

13. The combination, to form a self-exciting alternating dynamo-electric machine or motor, of alternating coils arranged upon the armature, two or more sets of exciting-coils disposed upon the armature, and a, suitable commutator therefor, to which the coils are connected in such manner that during a portion of the revolution of the armature coils in similar positions relative to the inducing-field shall be simultaneously cut out of circuit.

In testimony whereof We have hereunto set our hands and aflixecl our seals, this 10th day OfSeptember, 1888, in the presence of the two subscribing Witnesses.

MERLE J. WIGHTMAN. [L. s.] ELIHU THOMSON. LL. s.j

Witnesses:

J. W. GIBBONEY, F. C. LEMP.

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