Untitled record

Application filed April 2, 1885. (No model.)

To all whom it may concern:

Be it known that I, Elii-iuThomson, a citizen of the United States, and a resident of Lynn, in the county of Essex aud State of 5 Massachusetts, have invented a certain new and useful Automatic Commutator-Adjuster for Dynamo-Electric Machines, of which the following is a. specification.

The object of my iuveution is to prevent io sparking at the commutators of dynamo-electric machines. It is well known in the operation of such machines that when the strength of the current delivered from the armature of the machine changes through any difference 15 in the resistance of the circuit due to differences iu the number of lamps or other devices in operation, the so-called “neutral” lineshifts, aud if the brushes be unadjusted to follow such shifting a sparking will occur at the comma20 tator.

My invention consists in automatically shifting the brushes, to follow the shifting neutral liue, through the agency of a load or strain detector applied to the, driving-power 25 of the machine in such way that the increase of load put upon the driving-power by increase iu the current delivered from the armature shall be felt, and shall cause an automatic adjustment of the commutator-brushes 30 or commutator-cylinder iu the proper' direction to avoid spark.

My invention is particularly applicable to dynamo-electric machines when used for incandescent lighting or other purposes where, 35 through the variations in the number of translating devices in use, the current strength of the machine is subject to changes. Any device whereby the load imposed upon the driving-power in operating the dynamo may be 40 detected or felt may be employed in carryingout my invention, it only being necessary to connect such load or strain detector through suitable intermediate mechanism with the moving parts of the adjustable commutator in 45 such way that' the movement of the load or strain detector, consequent upon an increase in the power required to drive the dynamo, shall effect au adjustment of the commutator.

Some of the ways in which my invention ju may be carried out are illustrated in the accompanying drawings.

Figure 1 is an elevation of apparatus simply formed, in which the devices are combined according to my invention for the purpose of moving the commutator-brushes. Fig. 2 illus- 55 trates an arrangement whereby an adjustment of the commutator-cylinder may be effected in obedience to changes in the load put upon the driving power. Fig. 3 is an elevation of a detail of construction. 60

Referring to Fig. 1, A indicates the armature of a dynamoelectric machine; K, the commutator; Y, the yoke that carries the commutator-brushes, and that may, as usual, be shifted to move the brushes backward aud 65 forward upon the commutator-cylinder.

G indicates an outside or working- circuit connected to the commutator and supplying incandescent lamps or other devices in multiple arc after the usual manner. 70

The field-of-force magnet of the machine is indicated at M, aud is here shown as connected in a derived circuit of high resistance to the outside or working circuit after a wellknown manner. 75

The commutator K is of any desired type, and is connected, as usual, to the coils upon the armature A. The winding of the field-magnets M is immaterial, and may be a “ series ” winding, “shunt” winding, or “compound” 80 winding.

The yoke Y is connected by a link with, the lever L, carrying an idler-pulley, I, that bears upon the beltB, and serves to move the yoke and brushes in obedience to varying strains 85 put upon the. belt through variations in the load. The spring S, applied to the lever, causes the pulley to bear upon the belt, so that the varying tension of the belt may move the lever. 90

It is desirable to have a second idler, I', (indicated iu dotted lines,) carried from a frame suspended from the lever L, so as to take up the slack of the belt on the side B' when the idler I yields to the increased strain on the 95 side B. The adjustments are made such through change of leverage or otherwise that when the load is light, due to the number of lights or. other devices upon the circuit G being small, the driving strain on the belt B 100 being correspondingly small, the brushes carried upon the yoke Y will be upon the proper neutral line of the commutator to prevent sparking. When, however, the number of

323,976 lights or other devices supplied in multiple arc from the circuit G is increased, thus decreasmg the resistance for the armature, demanding more current and putting more load upon the machine, the belt P> will become more tense, and the idler-pulley I will be raised, so as to move the lever L and shift the commutator-brushes forward, so as to follow the shifting neutral line, which, as is well understood , will move forward with the increased current and load. In a similar way a backAvard movement will occur through the action of the spring S when the load decreases, so as to follow the shifting neutral line in a backward direction.

Fig. 1 is an example only of a way of applying my invention, and T do not by any means confine myself to the particular set of devices there shown.

In Fig. 2 I have illustrated another construction of load or strain detector and another way of applying the same to the commutator so as to effect an adjustment of the latter in correspondence witli variations of load. In the latter instance the arrangement is such that the commutator-cylinder may be adjusted instead of the commutator-brushes. In either case, however, it is to be understood that the commutator is adjusted, and by “adjustable commutator” Imean any commutator so constructed that either the brush or commutator cylinder may be adjusted so as to follow the shifting neutral hue.

The brushes B² Β² are supposed to be fixed and set by hand in the position required for normal work. The commutator-cylinder K is, however, loose upon the shaft, and is connected with devices, to be presently described, whereby it may be shifted backward ou increase of load, so as to produce the same adjustment in effect as would be produced, by shifting the brushes forward iu the direction of revolution.

The armature A is loose upon the drivingshaft X, aud the connections from the coils thereof to the commutator-cylinder K are made flexible, so as to permit the movement of one with relation to the other. The armature is driven from a pulley, P, fixed upon the shaft X through the springs S S or other flexible yielding devices, which connect said pulley with a disk, D, or other device secured to the armature. This arrangement constitutes a load or strain detector, and permits an angular movement of the armature-shaft X and pulley P with relation to tlie armature upon an increase of the load. The springs S are connected to pins or studs borne by disks, which are respectively fastened rigidly to the armature A and the pulley P.

In Fig. 3 the studs d d are supposed to be those carried by the disk D, and the studs ji p are attached to the disk carried by the pulley P. The springs S S are attached at one end to the studs d, and at the other to the studsp. The obvious result of attempting to rotate the pulley P will be to extend the springs S with a force depending on the opposition of the armature to rotation iu its magnetic field.

The relative angular movement of the shaft 70 X and pulley P withrelation to the armature is imparted, through a set of gears (indicated at G²) analogous to the back gear of a lathe, to the commutator cylinder. Other devices than those shown may be employed for imparting 75 such movement-; but those, indicated form an effective and simple device, and also provide for imparting a magnified movement to the commutator-cylinder Iv.

The gear-wheels e b are carried upon a shaft 80 mounted in an arm extending from the driving shaft X and gear, respectively, with a wheel,/, connected to the commutator-cylinder, and with a wheel, «, connected to the armature. A counterpoise-weight, W, for 85 keeping the parts balanced during rotation, is preferably provided. The wheel e is made larger in diameter than the wheel b.

The operation of this arrangement is as follows: AVhen an increased current is developed 90 in the armature A from any cause—as, for instance, by increasing the number of devices in multiple arc upon the circuit from said armature—au extension of the springs S S to a greater degree is caused, and a movement of 95 the shaft X with relation to the armature occurs, thus causing a movement of the arm carrying the gears e b and a rotation of said gears iu such direction as to move the commutator-cylinder backward in a direction op- 100 posite to the direction of rotation, thus bringing the point of neutrality into coincidence with the fixed brushes, assuming them to have been correctly set at the start.

In dynamo-electric machines of most types 105 a shifting of the neutral line takes place in a forward direction corresponding to the direction of rotation of the armature upon au increase of the current or load due to increase of the number of lamps iu multiple arc. no My invention provides au effective means of weighing the increased load, and imparting to the commutator an adjustment in the proper direction to measurably compensate for the shifting of the line upon Avhich brushes 115 should bear, in order that little or no sparks may occur upon the commutator-cylinder.

By tlie term “load or strain detector” I mean any mechanical devices whereby the increased resistance ofthe armature to rotation may be 120 indicated, or may Avork a movement of parts from which movement may be communicated to the commutator in proper direction to compensate for shifting of the neutral line.