US660054A - Controlling-brake for motors. - Google Patents

Description

No. 660,054. Patented Oct. 16, I900.

A. C. EASTWOOD.

CONTROLLING BRAKE FOB MOTORS.

(Application filed May 14, 1900.) (N0 MfldeL) 2 SheetsESheet l.

fiz 54 M WW Patented Oct. l6, I900. 000.

FOR MOTORS.

ad m 14, 1900.

2 S heets$heet 2.

A. c. 'EASTW CONTROLLING BRAKE (Application in (No Model.)

UNITED STATES PATENT OFFICE.

ARTHUR O. EASTlVOOD, OF ENSLEY, ALABAMA, ASSIGNOR TO THE ELEU'TtIC CONTROLLER AND SUPPLY COMPANY, OF CLEVELAND, OHIO.

CONTROLLING-BRAKE FOR MOTORS.

SPECIFICATION forming part of Letters Patent No. 660,054, dated October 16, 1900.

Application filed May 14,1900. serial No. 16,635. (No model.)

To all whom it may concern:

Be it known that I, ARTHUR C. EAsTWooD, a citizen of the United States, and a resident of Ensley, Alabama, have invented certain Improvements in Controlling-Brakes for Motors, of which the following is a specification.

My invention relates to certain improvements in controllers for electric motors.

I have shown my invention applied to the controller for which a patent was granted to A. O. Dinkey on July 7, 1896, No. 563,575.

The object of the invention is to apply a braking force to a motor by means of connections on a controller which will make the motor act as a generator, the speed being controlled by varying the resistance in circuit.

Referring to the accompanying drawings,

Figure l is a perspective view of my improved 2o cont-roller. Fig. 2 is a diagram View showing the wiring when my invention is used in connection with a Din key controller. Fig. 3 is a diagram view of a modification. Fig. 4 is a view showing diagrammatically the circuits through the controller and motor when the controller-handle is so thrown as to change the motor to a generator.

H is the frame of the controller, having a cylindrical slate tablet H, to which the contact-plates are secured.

I is the contact-arm, mounted on the shaft 1, having its hearings in the frame, and this shaft is geared to an operating-lever J in a manner similar to that described in the Dlnkey patent, above referred to. There are two series of concentric contact plates or blocks, one mounted within the other, and on the arm are contactfingers f t', which make contact with the plates or blocks.

40 B, B B and B of the outer circle B and B pf the inner circle are the ments which are required by the brake. necessary connections between these ments are made by the fingers of the con- 5 troller-arm. No change in or addition to these fingers is made necessary by the addition of my improved brake mechanism to the controller.

The blocks R to R inclusive, represent the resistance-blocks found on the Dinkey type of controller, while the blocks D D D and seg- The seg- D of the outer series and the blocks D D D D of the inner series are dead-blocksthat is, when the fingers of the controller-arm are on these blocks the motor is receiving no current and can coast under its own momentu m. The plates 0 O are contact-plates, upon which the fingers of the contact-arm rest when covering any pair of the resistanceblocks. If, for instance, the controller-arm is in the extreme position a I) when it is desired to stop, resistance is cut in through the resistance-segments R R &c. When the segments D, D D and D are reached by the fingers of the contact-arm, the motor receives no current, as mentioned above, and coasts under its own momentum. As it moves into the next position B is connected to B and B to B, as shown diagrammatically in Fig. 4. This connects the motor as a series generator, the connections beingsuch that the currentgenerated tends to build up the residual magnetism of the fields. This throws a load'on the ar mature, and it comes to rest immediately or gradually as it is allowed to generate more orlesscurrent. Followingthecontroller-arm from the other extreme position 0 d to the horizontal position, it will be seen that B is now connected to B and B to B. This reverses the connections of the armature and fields; but since the armature is traveling in the opposite direction the electromotive force is also reversed, and hence the current traverses the field-coils in the same direction as before and the machine builds up as a generator.

For regulating the current generated, and hence the braking force, in the case of the trolley or hoist of a crane, where the momentum of the load is never Very great, in place of connecting B to a it may be connected to any of the resistance-segments R R the. ,thus throwing more or less resistance in the circuit.

I have found by experiment that the current generated in the above cases is so small 5 and of such short duration that the controller resistance is not perceptibly heated. Hence IOO is automatically connected across the fieldterminals; By varying the resistance of this shunt the fields are more or less highly excited and the current thus controlled. This shunt is connected between D and D and by connecting D and D and D and D the same shunt can be used going in either direction. In this case the segments are so designed that in one position of the armthe fingers make contact on both D and B on one side and D and B on the other side and in the other po sition contact is made on B and D and B andD Thisiseasilyaccomplishedbychamfering the adjoining edges of the segments in such a way that the fingers drop into the groove thus formed. Thus it is seen that the energy due to the momentum of the armature and the load to which it is attached form, primarily, the braking force. Hence no useful power is expended in making the stop. The braking force is applied directly to the armature, where it has the greatest advantage, and is applied without the intervention of solenoids, brake-bands, or friction devices.

The device forapplying the brake can be ap' plied directly to the controller or starting-box by means of which the motor is operated. The motor is thus under the complete control of one lever. No additional wires are necessary between the motor and the controller.

In the case of a reversing-motor the segments and contact-fingers are arranged in such a way that the armature is brought to a stop before the current can be reversed through it. Thus the possibility of plugging the motor is precluded. By plugging is meant the sudden reversal of the current in the armature. The heavy rush of the current due to this and its consequent bad effect upon the armature is well known. This alone is an extremely-valuable advan tage which the device possesses. Its use as a brake in connection with the controller puts the motor under complete control, which, for instance, in crane-service is of great valve.

Equipped with my improvement the trolley can be run out all the way at full speed, the

a quick positive stop owing to the air which the brake-band entrains between itself and the brake wheel. lVith the controllerbrake the stop can be made as quick and decisive as desired.

When my invention is applied to a motor running in one direction only, I design the controller as shown in the diagram Fig.

I claim as my invention-- 1. The combination in a motor-controller, of two series of concentrically-placed resistance-blocks, a contact-arm having four sets of fingers thereon constructed to bear on said blocks, two series of brake-blocks placed similarly to the resistz'tuce-blocks in the path of the contact-arm, connected to the motorcircuit and disconnected from the line,whereby the motor is made to act as a series generator when running under its own momentum, thus retarding the motion of the armature Without using current from the line, substantially as described.

2. The combination in a 1notor-controller of two concentrically-arranged series of contact-pieces, a contact-arm and two sets of contact-lingers thereon, movable over the contact-pieces, said pieces consisting of resistance points or blocks, brake-blocks and deadblocks, the dead-blocks intervening between the resistance and the brake blocks and the brake-blocks being connected to the motorcircuit and not to the line, thereby short-circuiting the motor on itself when the said con tact-arm rests on the brake-blocks, substantially as described.

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

ARTHUR G. EASTWOOD.

Witnesses:

J. A. ()BENCHAIN, H. S. CHILEs.

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