US457330A - Wash ihoton - Google Patents

Description

. (,No Model.) 3 Sheets-Sheet 1.

T. B. ADAMS. AUTOMATIG BRUSH SHIPTBR FOR DYNAMG ELEGTRIG MACHINES. No. 457,330. I Patented Aug. 4, 1891.

(No Model.) 3 sheets-Sheet 2.

T. E. ADAMS. AUTOMATIC BRUSH SHIPTER ECR DYNAMO ELECTRIC MACHINES.

No. 457,330. Patented Aug. 4, 1891.

n4: mams nus cn., wom-uma., msnm-run, n. c.

(No Model.) 3 Sheets-Sheet 3.

T. E. ADAMS. AUTOMATIC BRUSH SHIPTER POR DYNAMO ELEGTRIG MACHINES. No. 457,330. Patented Aug. 4, 1891.

@www/t0@ A l 9km... (S, (www @2mg Ll/0 awo/www( www ' self. indeed, its only drawback being the disturb- UNiTED STATES PATENT OEEICE.

THOMAS E. ADAMS, OE CLEVELAND, OHIO, ASSGNOR TO PHE BRUSH ELECTRIC COMPANY.

AUTOMAT|C-BRUSHSHIFTER FOR DY'NAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 457,330, dated August 4, 1891.

Application filed September 16, 1887. Serial No. 249,860. (No model.)

To all whom t may concern,.-

Be it known that I, THOMAS E. ADAMS, of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Automatic Brush- Shifters for Dynamo-Electric Generators; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has reference to automatic brush-Shifters designed for use more particularly in connection with the Brush constantcurrent dynamos and other dynamos of this type. The Brush constant-current dynamo and its current-regulator are both well known to and understood by those skilled in the art, and for the purpose of this application it is only necessary to mention that its regulationi'. e., its constancy of current under various changes of external resistancedepends on the resistance of the regulating branch in multiple arc with the field-exciting coil. The well-known Brush regulator for constant current varies this branch resistance in inverse proportion to the variations of the external resistance. It follows, therefore, that as the latter varies so does the regulator vary the intensity of the magnetic 'field acting on the ari'nature, therebyincreasing or reducing the electro-motive force and keeping the ratio v-constant, and thereby also the current it- This device fulfils its purpose very well ing and changing of the proper proportion between the mutually-reacting intensities of the magnetic force due to the field-magnets and of that due to the armature itself, which is kept constant, and as a certain ratio between these two forces coincides with a certain position of the resultant poles on the armature-ring it becomes self-evident that a variation of only one of these two forces must also cause a variation of the position of the resultant pole and w' h it of the diameter of commutation. If, then, the brushes are not The more the diameter of mined position-as, say, the maximum exter-` nal resistance-the more excessive and mischievous will be the sparking. At the same time practical observations on Brush constant-current dynamos have shown that for a given diameter of commutation the brushes may be moved to and fro on the commutator for a considerable distance without materially aifecting the current strength, and it will therefore be practicable to let the brushes follow the varying movements of the diameter of commutation, therebysuppressingthedeleterious sparking without affecting the current strength or interfering with the proper action of the current-regulator. Heretofore the brushes have been moved by hand for the specified purpose; but my present invention covers the automatic moving of the brushes in conformity with the varying movements of the diameter of commutation for the purpose of suppressing excessive sparkingat the commutator. All the automatic brush-shifting devices known to me have the purpose of regulating the current strength thereby, while the automatic moving of the brushes in my invent-ion has nothing whatever to do with the regulation of current strength, but aims exclusively at the suppression of sparking, it having no eifect on the current regulation. rlhe distinction between myinvention and other automatic brush-Shifters is thus made perfectly plain.

'lo carry out my invention I employ electro-magnets or solenoids or weights, or a combination of the same, and to further explain it I have illustrated in the accompanying drawings, which form a part of this specifican tion, several forms of the automatic brushshit'ter as applied to constant-current fieldshunt-regulated Brush dynamos, or to* other similar dynamos.

In the drawings, liigure l represents a perspective view of my collecting-brush shifter, with the armature, the field-magnet coils, and the circuit connections represented diagrammatically. Fig. 2 is a longitudinal section of a graduated check-weight used in connection with my brush-shifter. Figs. 3, 4, 5, 6, 7, and 8 illustrate various modifications of the principal part of my improvement; Figs. 9 and l0, an end elevation and plan, respectively, of

the commutator and balancing-weight; and Fig. ll, an elevation of a modified form ot' graduated check-weight.

Referring now more particularly to Fig. l the general arrangement ot' a Brush dynamo is there represented diagrammatically by the armature-coils l 2 3 7 8 and by the iieldmagnet coils G G2 G3 G4. The terminals of the armature-coils are connected, as usual, with the commutator-segments on the commutator-disks A A', and the collecting-brushes B B2 B3 B4, bearing upon the commutators, are adjustably mounted upon a carrier C, which is pivot-ally connected with a standard D, and which is provided with a handle M, by means of which the shiftin g of the brushes may be effected manually, if so desired. Two electro-magnets or solenoids E and F are located one on each side of the pivot of the brush-carrier, and their armatures or cores are connected by links E F', respectively, with the brush-carrier, one on each side of the fnlcrum of the same, so that it either solenoid becomes active it will swing the brushcarrier in the direction of its pull, making the brushes assume different positions upon the commutators.

H represents an ordinary current-regulator employed for the regulation of Brush dynamos. It is composed in the main ot a variable resistance R, included in the regulating-shunt or governing-circuit K, a governing magnet or solenoid Q in the external circuit J, and a dash-pot. The operation, as well as the construction, of this regulator is well understood by those skilled in the art, and need not here be particularly described.

The circuit connections are as follows: Brushes B B2 B3 B4 are connected by iiexible conductors d d2 di dl with posts or plates l, P, O,'and L, respectively. Post I also forms one terminal of solenoid E, the other terminal of which is connected with the field-magnet coils, and there is also an electric connection from post l to the switch-post y, which in turn is connected with the variable resistance R, the other terminal of the resistance being formed by the switch-point Post P, which may be an ordinary binding-post, is connected with the governing-magnet Q, which, as has been stated above, is in the external circuit J, terminating in abindin g-post N, Jfrom which a connection is made to post O. Post L constitutes the other terminal of the field-circuit and one terminal of solenoid F, the other terminal of which is connected with switch-point fr. Solenoid E is of coarse wire, and is adapted to carry the normal current of the field-magnets, with which it is connected in series, as will be seen by tracing the connections above described. Solenoid F is wound with Iine wire capable of carrying the maximum current in the governing-shunt of the dynamo, of which shunt it forms a part.

The circuits ot the apparatus can now be easily traced as follows: The current from the armature which reaches commutator-disk A is carried by brush B' and exible connection d to post I. Here the current divides, the main branch passing through solenoid E and the field-magnets to post L and the govern` ing branch to switch-point /y through the governing-circuit K, resistance R of the regulator H to switch-point 0c, and through solenoid F to post L, where the eld and governing branches unite. The current then passes by iiexible connection (Z4 to collecting-brush B, commutator-disk A, and through the other coils of the armature to collecting-brush B2 and by flexible connection Z2 to binding-post P. From P the current passes through the external circuit, including governing-magnet Q, to binding-post N, which connects with post O, and from where the circuit is completed by flexible connections d, collectingbrush B3, commutator A, and armature back to collecting-brush B. It will be observed that the more current passes through the shunt resistance the smaller will be the magnetic force of the field-magnets and the greater will be the displacement of the diameter of commutation in the direction of the rotation of the armature, and vice versa. When the dynamo is started, the resistance of the shunt is at its maximum, and very little current being diverted from the held-magnets and solenoid E, the latter will be sufficiently energized to swing the brush-carrier to its own side of the pivot, and the lead oi the brushes will approximately coincide with the then diameter of commutation, thus preventing tiashin or current-breaking. As the cu rrent increases in strength, solenoid F will be energized to a greater extent and the collecting-brushes will continue to move in a direction opposed to the rotation oi' the armature. This movement will be gradual as the increase of current strength is also gradual. lt the current becomes too strong, the regulator acts to reduce the strength ot the field-magnet coils, and since the solenoid E is in series with the field-coils its magnetic strength is also weakened, while by the greater amount of diverted current in the shunt solenoid F is strengthened until it overpowers solenoid E, when the brushes are shifted in the opposite direction, as required by the new position of the resultant magnetic pole. This action is also gradual, since the regulator H acts slowly and gradually, owing to the dash-pot which is used in connection therewith. Il' the current is ot' normal strength, the portion of it diverted into the shunt will energize solenoid F sufficiently to just balance solenoid E, and this balance will be maintained so long as the current maintains its normal strength. It will now be understood that any variation from the normal strength ol' the current in the main line will disturb the equilibrium of forces residing in the two solenoids, and any difference between those two forces will consequently move the brushes in the sense and to the extent of such difference. Electro-magnets may take the place of solen- IOO oids when desirable. In some forms it is impracticable to permit the solenoids to act unchecked upon the brush-carrier, for in that case, while the sparking would be reduced to a minimum the fluctuations of current in the external circuit would be too great for practical purposes, and for this reason it is necessary to make provision for checking the action of the solenoids; and thislaceomplish by means of a graduated check-weight IV, two forms of which I have shown in Figs. 2 and ll, respectively.

In Fig. 2 the graduated check-weight NV consists of a sleeve or tube a, having a series of rings D D2 D11 D12 placed vertically above each other within the tube, the inner diameter of each successive ring being greater than that of the preceding one, whereby a series of ledges is formed, upon which the weights @U2 w3 co4 w w12 loosely rest. These weights are centrally perforated, and through them passes a sleeve or tube c loosely, while a weight w', also centrally perforated, is fixed to the lower end of said tube and rests upon the bottom of tube a. A guide-pin b is lixed centrally at the bottom of sleeve a and passes through the central perforation of weight yw andinto tube c. A perforated cap c is screwed upon the sleeve ct and serves as an additional guide to the tube c in its upward and downward movements. It will now be understood that ifltube c is raised it will carry weight w with it until the lat-ter comes in contact and lifts weight w2 from the ledge upon which it rests. A continued upward movement of tube c will lift successively Weights 103,104,102 and w12. If from this elevated position tube c is allowed to descend, it will drop successively the weights w12 w11 w3 102 until weight w again comes to rest upon the bottom of tube a. By

reference to Fig. l it will be seen that the check-weight arrangement is pivoted by a lug Z, projecting from the bottom of tube a, to the base-plate of the apparatus, and that tube c is pivotally connected to one end of the brushcarrier. Thus as the brush-carrier is rocked by the action of the solenoids E F weight fw is actuated in the lnanner of a piston of a pump, and its weight is increased step by step as it ascends and is decreased step by step as it descends, the increasing and decreasing weight being graduated to correspond to and to counterbalance the increasing and decreasing pull upon the commutator-brushes.

Another form of graduated check-weight is shown in Fig. Il. It consists of a series ot graduated Weights lw 102 w12 freely piled upon each other, but connected by links Z Z of graduated length, which when the weights comek into contact are received in recesses r o, formed in the faces of the weights, as indicated in dotted lines. The masses of the weights are graduated in the same manner as the corresponding weights shown in Fig. 2, and the lengths of the links are graduated like the distances from each other of the weights shown in Fig. 2. The uppermost weight w is pivotally connected with the brush-carrier, as shown. The operation of this form of graduated check weight is Very much like that shown in Fig. 2; but it is deemed unnecessary to dwell upon the details of construction, since this check-weight will be made the subject of a separate application.

It is well known that the collecting-brushes bear with considerable force upon the commutators, and the brush-carrier being' delicately pivoted there will be a tendency in the commutator to carry the brushes forward by frictional hold upon the same in the direction of rotation. To overcome this tendency I make use of a weight movable to or from the center of the carrier, the arrangement of which is clearly shown in Figs. 9 and IO. The bar Z is fast upon the brush-carrier C, and extends upon a line, or nearly so, radial to the commutator. It is secured at its middle with its two halves extending freely toward and from the center of the commutator, respectively. A sliding weight Z can be placed upon either side of the bar and moved from and toward the center of the commutator to compensate a greater or less frictional pull upon the brushes, which depends upon the greater or smaller pressure upon the commutator with which the brush is set. rlhe sliding weight is held in its adjusted position by a set-screw Z2.

In place of two solenoids E F and their circuit connections numerous other arrangements involving the same principle or similar principles of action may be employed. Some of these forms I will now describe.

In Fig. 3 the solenoid F is modilied by making it of two distinct spools, one of coarse wire included in the external circuit between the binding-post N and post O, and the other of line wire connected in circuit in the same manner as solenoid F, in Fig. I.. The two coils are wound in the same direction, so that the currents passing through the same will coact, the coarse-wire coil exerting a constant pull upon the core. The objection to this form is the liability of the insulation to burn out, owing to the great difference of potential between the coarse and iine wires.

Fig. 4 is another modilied form, in which spool F is composed wholly of coarse wire in the external circuit, between the posts Nand O, while solenoid E is composed of a coarse and fine wire spool wound in opposition to produce differential action, the coarse wire in this case being connected in the circuit in the same manner as solenoid E in Fig. I, while the tine-wire coil is in the governing branch, the same as solenoid F in Fig. l. In this case solenoid F exerts a constant pull upon the brushes sufficient to move the same, when enough current traverses the fine Wire -on solenoid E to neutralize the pull of the coarse wire.

ln the modification shown in Fig. 5 solenoid F is altogether omitted, while solenoid E is constructed with a coarse and fine wire coil,

IOO

IIO

the course wire being in series with the fieldmagnet and the fine wire being in the shunt, and the current in the same fiowi'ng in opposite direction to that in the coarse wire. In this construction the forward movement of the brushes is effected frictionally, which, however, can only take place when the backward pull of the coarse wire is neutralized by the counteracting force of the current in the fine wire, and it will be understood that in this modified form, as well as in others, the check-weight arrangement must not be omitted.

In the arrangement shown in Fig. 6 the shunt-circuit is not used at all. Solenoid F is in the external circuit and exerts a constant forward pull against the opposing pull of solenoid E, which latter being in series with the field-magnets varies in strength with the same. rllhese variations of strength of the field-magnet coils necessitate the moving of the brushes, which in this case should be accurately effected by the corresponding variations in solenoid E; but the greatly varying friction of the parts renders this form of apparatus somewhat objectionable in practice.

In the modification shown in Fig. 7 both solenoid F and the shunt-circuit are omitted. The forward movement of the brushes is effected by friction of the same upon the commutator, and the backward movement is effected by the pull of solenoid E, as in the other forms. The same objections which may be urged against the arrangement shown in Fig. 6 also apply to this form. I

Another modification is shown in Fig. S, where solenoid F is composed wholly of fine wire in the shunt-circuit and acts to move the brushes forward against the pull of the check-weights, which, when there is little or no current in spool F, overcomes the friction of the brushes and moves the brushes backward to the limit of their travel. The operation of this modification is as follows: When the current is started, the resistance of the shunt is at its maximum and but little current can pass through it while the brushes are, as we have seen, back at the limit of their travel, which position they also occupy when there is a full load on the dynamo. If now lamps are switched off or the speed of the dynamo is increased, the regulator w1ll reduce the resistance of the shunt, more current will dow therein, and the strength of the solenoid F will be increased, which will enable it to pull down one end of carrier C and raise the opposite end, to which tube c of the check-weight device is attached. 'Weight u" will be lifted until it touches in turn weight 102, and the brushes are thereby moved forward proportionate to the distance between ui and w?. Thus it will be seen that the distance the brushes are shifted at each step depends upon the distance of one weight from the other, and the change of load 1n the dynamo which is necessary before the brushes move is directly dependent upon the mass of the weights. I am thus enabled to reduce the sparking to a practical minimum for different loads upon the dynamo by graduating the distances between the successive weights w we, tbc., and the masses of said weights.

Should more load he thrown off, as by the switching off of other lamps, weight fw? would be lifted until it came in contact with weight w, dsc., until, when all the load is off, the brushes are at the limit of their forward movement. Increasing the load of the dy namo will of' course reverse this operation.

It will be understood that the devices hereinbefore described may be modified to oper atc in connection with dynamos regulated by regulating the resistance of the field-magnet coils or with dynamos of the compound type. By a modification of a check-weight device the brushes can be automatically shifted on straight-sluint dynamos; but my present i11- vcntion does not extend specifically to such modifications, since I propose to claim the same iu a separate application.

Having now fully described my invention, I claim and desire to secure by Letters Patentl. The combination, in a dynamo-electric generator having a current-regulator in a shunt around the field-magnets, of a brushcarrier controlled by the differential action of the currents in the field-circuit and in the governing-shunt, with a graduated checkweight acting upon the brush-carrier for determining the extent of shift of the brushes for a given change of load, substantially as and for the purpose described.

2. The combination, in a dynamo-electric generator having a current-regulator in a shunt around the field-coils, of a pivoted brush-carrier controlled by the differential action of the currents in the field-circuit and in the governing-shunt, and a pivoted graduated check-weight device acting upon the carrier for determining the extent of shift of the brushes for a given change of load, substantially as described.

3. In an apparatus for controlling thelength of spark at the commutators of such dynamoelectric generators, in which the strength of current is governed by a shunt of variable resistance around the field, the combination of a solenoid in the field-circuit adapted to carry the normal current through the field, and a solenoid in the governing branch adapted to carry the maximum current in the latter, with a pivoted brush-carrier controlled by the differential action of the solenoids, and a sliding weight for counteractin g the frictional drag of the commutator upon the brushes, substantially as described.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

THOMAS E. ADAMS. lVitnesses:

W. A. PALLANT, A. CALHOUN.

IOS)

IIO

Images