US743082A - Dynamo-machine. - Google Patents

Description

No. 743,082. PATENTED NOV. 3, 1903. D. G. JACKSON.

DYNAMO MACHINE.

APPLI OATION FILED AUG.11, 1902.

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' W @W% W Attorneys Patented November 3, 1203.

PATENT OFFICE.

DUGALD O. JACKSON, OF MADISON, VISCONSIN.

DYNAMO-MACHINE.

SPECIFICATION forming part of Letters Patent No. 743,082, dated November 3, 1903.

Application filed August 11, 1902. Serial No,l19,Z69. (No model.)

To all whom it may concern.-

Be it known that I, DUGALD O. JACKSON, a citizen of the United States, residing at Madison, in the county of Dane and State of Wisconsin, have invented a certain new and useful Improvement in Dynamo-Machines, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to dynamo-machines, and has for its object the provision of means whereby sparking at the brushes may be avoided without resorting to the usual alternative of shifting the brushes.

More particularly my invention relates to the excitation of the field-magnets of dyna mo-machines having coinmutators in such a way that the lines of magnetic force will always thread through the armature with an approximately constant fixed direction and strength without regard to variations of current in the armature-coils or to the direction of rotation of the armature. By thus maintaining a constant direction and strength of the magnetic field it is unnecessary to shift the position of the brushes under varying conditions of current, pressure, or speed, and while the brushes remain in but one position sparking at the commutator is almost entirely avoided.

As is well understood by those skilled in the art, it is necessary in a motor or generator in order to prevent sparking to maintain a practically constant angle between the diameter of commutation and the direction of the lines of force through the armature. If the field-magnets of a dynamo-machine are excited by the customary field-windings, lines of force flow between the pole-pieces in a certain direction. If now an electric circuit be closed through the rotating armature, electric currents will be set up in the armature-conductors, which currents in turn will cause lines of magnetic force to flow about each conductor. Some of the armature-conductors will have a position such that the lines of force they set up will fiow in a direction more or less at right angles with the path of the lines of force set up by the field-magnets. The conductors which set up these lines of force at right angles to the normal field are commonly known as cross-turns. The result is that instead of having a magnetic field due to the magnetization of the field polep'ieces alone there is a resultant field, whose direction is determined by the relative strength of the magnetic field due to the armature cross turns as compared with the strength of the magnetic field caused by the field-magnets, and as the current varies in the armature cross-turns the strength of the corresponding magnetic field will vary, thus causing a variation in the direction and strength of the resultant magnetic field threading the armature, and to maintain a constant angle between the direction of this resultant field and thediameterofthe commut-ationitis apparent that as the direction of the field varies, due to variations of current in the armature crossturns, the direction of the diameter of commutation will also have to be changed. This changing of the position of the brushes is an objectionable feature in the regulation of dynamo-machines, whether it be accomplished by hand or by more or less automatic means. It has therefore been proposed to magnetically neutralize the effect of the armature crossturns by associating with each armatureconductor a parallel conductor stationarily mounted outside, but near to the periphery of the armature, in which neutralizing-conductor equal electric currents flow, but in opposite directions to the currents in the armature-conductors. Theproposed embodiments of this idea have contemplated an iron fieldmagnet made in the form of a ring which entirely surrounds the armature and about which the neutralizing or compensating conductors are wound,as on a Gram me-ring armature. This isan expensive construction and an undesirable form of field-magnet. Other embodiments of this idea have been unsuccessful because of incomplete compensation of the cross-turns or because the compensating conductors have not been properly placed with reference to the armature-conductors, and, furthermore, the winding of the compensating conductors has heretofore been unduly expensive and they have been difficult to properly insulate.

My invention contemplates an improved method of winding compensating conductors, whereby every armature-conductor will be paralleled by a compensating conductor disposed with corresponding angularity about the armature-axis. The compensating winding is thus electrically identical with the armature-winding, except that the currents flow in one direction in an armature-conductor and in the opposite direction in the adjacent compensating conductor. In order to accomplish this perfect compensation at a small cost and at the same time to retain the present eiiicient form of field-magnets, I preferably provide bridges inserted between poletips. These bridges are preferably of nonmagnetic and may be of non'conducting material; but they may be made of iron under some conditions. The compensating conductors are preferably laid in uniformlyspaced slots formed in the pole-faces and in the bridges similar to the slots within which the armature-conductors are laid. It will be seen that these slots may be very readily made in the pole-faces when the latter are made up of laminated iron punchings, as is nowadays frequently done. In this case it is evident that the slots may be punched in the pole-face punchings in a manner which is analogous to the Way in which the slots are punched in the armature-punchings.

It is a well-known practice among those skilled in the art to wind armature-coils on formers and then place them in the slots after the coils and slots have been duly insulated. The armature-coils are all alike. It is characteristic of the construction of my invention that all the compensation-coils are alike and that they may be wound up on formers and applied to the slots when the machine is assembled. Compensation-coils can thus be independently insulated, following the manner of insulating the armature-coils.

My invention will be best understood by reference to the accompanying drawings, in which 1 Figure 1 is a diagrammatic illustration of the armature and compensation-coil windings and connections. Fig. 2 is an end elevation of a dynamo-machine equipped with my improved compensation-coils. Fig. 3 is a perspective view of a single compensation-coil as wound upon a former.

Like reference characters refer to like parts in the various figures.

I preferably provide the usual field-frame 1, within which are mounted pole-pieces 2. The rotatable armature-core 3 is supported by bearings 4 and provided with a commutator 5. Brushes 6 6 are adapted to conduct current to and from the commutator. The spaces between the pole-pieces are filled in by the bridges 7 7, preferably of non-magnetic material.

For purposes of illustration I have shown the compensation-coils arranged to compensate the armature reactions for an armature which carries forty conductors and which is arranged to operate in a four-pole field and which has four ducting-paths through its windings. The armature-coils are laid in slots 8 8 of the armature-core and are held in place by the wedges 9 9, preferably made of wood or other insulating material. In a similar manner the coils of the compensationwindings are laid in the uniformly-spaced slots 10 10, cut in the pole faces and bridges, where they are held in place by the wedges 11 11.

Each'of the conductors 12 and 13 (shown upon the diagram of Fig. 1) may be considered to represent either a single conductor or the cross-section of a coil, the several coils being connected together in the manner illustrated by the end connections. The front connections are represented by the heavy lines, while the back connections are represented by the lighter lines.

In the drawings I have shown a four-path armature and have also shown the compensation-coils divided into four parallel paths. It is not essential, however, that the compensation-coils shall have the same number of parallel paths as the armature-coils, provided when exact compensation is required that the number of paths and conductors are so related to each other that the product of the number of conductors with the amperes carried by each is equal to the corresponding product of the number of armature-conductors with the amperes carried by each.

On some occasions it may be desired to somewhat overcompensate or somewhat undercompensate, and, again, it may be desired to alter the compensation. In this case the number of compensating conductors may be made different from the number required to cause the compensating ampere turns to equal the armature ampere-turns. The compensating ampere-turns, for instance, might be made larger than the armature ampereturns if all the current flowing through the armature were permitted to flow through the compensating conductors, and a shunt resistance may be placed between the terminals of the compensating windings, so that any desired portion of the armature-current will flow through the compensating windings. This shunt may be either a fixed shunt or a variable one. In the present embodiment of my invention I have shown such a variable shunt resistance at 14. The plus and minus terminals of the machine are shown at 15 and 16, the direction of current in the connectingconductors being shown by the arrows. The shunt-field-excitation winding is diagrammatically represented at 17, it being connected to the terminals 15 and 16.

In Fig. 3 I have shown a coil 18, having terminals 19 and 20, and which is adapted to be laid in slots for the compensating winding. It will be apparent that as the coils are uniformly spaced they are all alike and may be wound on the same former.

The construction illustrated is equally adapted for use on generators or motors; but it is particularly advantageous for use with motors which are desired to be operated at difierent times at widely-differing speeds. With the compensation for armature reactions here described the speed of the motor may be altered by varying the shunt-field eX- citation through a wide range without producing sparking at the brushes on the commutator.

It will be seen that my invention has, among others, a particular advantage as compared with the prior art in that it permits the use of independently-wound coils, (when this is desired,) which may be applied to the polepieces in a manner that is entirely similar to the manner of applying independently-Wound coils to the armature-core. It also has, among others, the advantage of being applicable to ordinary types of dynamos.

In this specification and these claims the term dynamo is used to mean either a generator or a motor, as commonly understood in ordinary electrical parlance.

While I have shown and particularly described one embodiment of my invention, it is evident that many modifications and changes might be advantageously made without departing from the spirit thereof, and I do not, therefore, Wish to limit myself to the precise disclosure as therein set forth; but,

Having described my invention, I claim as new and desire to secure by Letters Patent 1. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, slots formed in the pole-faces, and a compensation-winding laid in said slots, said compensation-winding being composed of previously-formed coils, substantially as described.

2. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, equally-spaced slots formed in the pole-faces, and a compensation-winding laid in said slots, said compensation-winding being composed of previously-formed coils, substantially as described.

3. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, and a compensation-Winding distributed about said armature at the polefaces, said compensation-winding being composed of previously-formed coils, substantially as described.

4. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, bridge-pieces between said polepieces, slots formed in the faces of said pole and bridge pieces, and a compensation-winding laid in said slots, said compensation-Winding being composed of previously-formed coils, substantially as described.

5. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, bridge-pieces between said polepieces, equally-spaced slots formed in the faces of said pole and bridge pieces, and a compensation-winding laid in said slots, said com pensation-winding being composed of previously-formed coils, substantially as described.

6. In a dynamo, the combination with a field-magnet having salient pole pieces, of an armature, bridge-pieces between said polepieces, slots formed in the faces of said pole and bridge pieces, a compensation-Winding laid in said slots, said compensation-winding being composed of previously-formed coils, and adjustable means for controlling the cur rent-flow through the compensation-windin g, substantially as described.

7. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, bridge-pieces between said polepieces, equally-spaced slots formed in the faces of said pole and bridge pieces, a compensation- Winding laid in said slots, said compensation winding being composed of previously formed coils, and adjustable means for controlling thecurrent-fiow through the compensation-winding, substantially as described.

8. In a dynamo, the combination with a field-magnet having salient pole-pieces, of an armature, a compensation-winding distributed about said armature at the pole-pieces, said compensation-winding being composed of previously-formed coils, and adjustable means for controlling the current-flow through the compensation-winding and the armature, substantially as described.

In witness whereof I hereunto subscribe my name this 28th day of July, A. D. 1902.

DUGALD C. JACKSON.

Witnesses:

GEORGE L. Calico, HARVEY L. HANSON.

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