US707300A - Controller for electric motors. - Google Patents

Description

No. 707,300. Patented Aug l9, |902. w. H. CHAPMAN. CONTROLLER FOB ELECTRIC MOTORS.

(Application filed Mar. 12, 1902.)

2 Sheets-Sheet I.

(No Modul SERIES No. 707,300. Patented Aug. l9, I902.

W. H. CHAPMAN.

CONTROLLER FOR ELECTRIC MOTORS.

(Application filed Mar. 12, 1902.)

(No Model.) 2 Sheets-Shet 2.

"m: NORRIS PEYERS co. Pnoimuma, WASHINGTON. D t.

UNITED STATES PATENT OFFICE.

IVILLIAM H. CHAPMAN,

OF PORTLAND, MAINE.

CONTROLLER FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 707,300, dated August 19, 1902. Application filed March 12, 1902. Serial No. 97,900- (No model.)

T0 at whom it Hung concern:

Be it known that I, WILLIAM H. CHAPMAN, a citizen of the United States of America, and a resident of Portland, Cumberland county,

. State of Maine,have invented certain new and ing to maximum and by which the motor may be reversed and to avoid complete interruption of the working circuit of the motor, and so do away with sparking at contact-surfaces, which is liable to stick the contact surfaces together by welding. I accomplish my purpose by means of rheostats with numerous steps of resistance and these steps representing a fine gradation from maximum to minimum current.

The usual practice in controlling motors is to use a switch for making and breaking the circuit, and if the motor is to be reversed a special reversing switch also is used, and these switches are operated to interrupt the whole current of the motor at its maximum, and a rheostat also is used of only wide enough range to cut down the current of starting to' the normal current which the motor is supposed to use. My controller, on the contrary, without the use of switches starts and stops the motor and reverses it by means of rheostats constructed to admit current gradually by fine gradationsand in one direction or the other through the armature of the motor.

I illustrate my invention by means of the accompanying drawings, in which Figure 1 is a front elevation of my controller with the connections shown diagrammatically. Fig. 2 is an enlarged section through the switchboard, and Fig. 3 is a detail of the spring which centers the rheostatarms.

B, C, B, and O are four sets of rheostatsegments, composed of thin copper sheets separated by mica and all clamped together by screws in the iron supportingframes A A, from which they are insulated'by mica in the usual manner. Each set of rheostat-segments is connected in the usual manner to a series of resistance-coils, (not shown), and the resistance of these coils in the successive steps increases by regular gradations from the outer extremes of each set toward the in ner extremes, which are located at the center portion of the supporting-castings A A. While the outer steps of resistance may be, say, three one-hundredths ohm, the inner steps are as high as thirty ohms each, and between these two extremes are all gradations. In practice I find that the steps should be such as will represent not much over one hundred watts--that is, the square of the current multiplied by the resistance of a step should not be much over one hundred. By following out this rule I obtain a rheostat which is practically sparkless from one extreme to the other.

The rheostats here shown are of the type which I may term difiierential rheostats that is, those in which as the arm moves from the center toward one end the resistance in one direction increases in the same proportion as it decreases in the other direction.

D and D are inverted-L-shaped levers or rheostat-arms, each pivoted at G G on a metallic stud. The vertical portion of these levers have brass fingers pivoted to them and actuated by springs s to press them into con: tact with the segments B B and O O. The lever D has an inwardly-projecting hub, Fig. 2, on which the levers E E are mounted and clamped. These levers have fingers c c,

pressed by springs into contact with the set of circular segments 1 2 3 t 5, which are mounted on the slate F. The levers D D are connected so that they move simultaneously. As here shown, they are linked together by the connecting-rod H, pivotally connected to the levers by studs which are insulated electrically from the levers, as shown in Fig. 2. On the lever D is a metal finger c pressed by spring into contact with the segments 6 7 8 9 10, mounted on the slate F. Means are provided for bringing the levers D and D back to a central or normal position when they are free to move. For this purpose I provide a pair of coiled springs 5, one on each end of the rod S, one end of the rod being pivoted to a stud s projecting out from the slate, and the center of the rod between the two springs slides through a socket 8 that is pivoted to the horizontal portion (1 of the lever D. Thus the tendency of these two opposing springs s is to bring the arm d to a central position on the rod. Solenoids are provided for operating the levers D and D to slide the contact-fingers along the rheostat.

The horizontal ends d d of levers D and D are pivotally connected with the links I I, and these in turn are pivotally connected to the iron cores J J of two solenoids K and K, which are mounted in an iron casing 70, attached to the slate F. At the tops of the two solenoids are air dash-pots L L, arranged to resist the movement of the cores upward, but not downward. The piston Z has ports Z controlled by loose disk-valves Z fitting over the stem Z which closes the ports when the piston goes up and allows them to open when the piston goes down. In the lower half of the dash-pot are grooves l and an opening Z so that the piston moves freely both up and down when it is in the lower portion of the dash pot. In the solenoid-circuit is placed an einergency-rheostat, by which resistance is inserted in the circuit when there is an excessive current over the main line.

At M is a solenoid whose iron core is supported by a spring a under compression. The upper end of the core is pivotally connected to a lever which operates over a rheostat or series of contacts connected to the set of resistance-coils R. Under normal conditions the spring holds the core up and keeps the leverfin one position on the upper contact of the series; but when this solenoid is excessively strong it overcomes the spring 6 and pulls the leverfto some lower portion of the series of contacts. The screw 9 serves to adjust the compression of the spring e, so that a greater or less current is required in the solenoid in order to pull the lever fdown from its normal position on the top contactpoint.

In directing the operations of my controller I make use of a differential rheostat located in any convenient place to be manipulated by an attendant and connected by three wires with the controller proper. This rheostatis composed of a metal lever N and contact-segments 0, connected to suitable resistances, and their resistances are so distributed that when the lever is in the central position it introduces an equal resistance between its point of contact and the two ends and in other positions an unequal resistance, which becomes more unequal as either end segment is approached. When contact is made with an end segment, the resistance is all cut out of that side and all inserted in the other side. One end segment is connected with one terminal of solenoid K and the other end segment to one terminal of solenoid K, and the other terminals of these two solenoids are connected to one line-terminal,while the lever N is connected to the other line-terminal through the wire m, in which, however, more or less of the resistance R is inserted whenever the lever f is pulled down. The effect of the insertion of resistance R is to weaken the force of both solenoids, allowing the spring on rod S to bring the levers D D nearer the central position.

T is the service-switch, which is kept closed during the hours of service of the motor to be controlled. From this switch the current is distributed by wires to the various circuits of the controller, which may be classified as follows: the armature-circuit, the shunt fieldcircuit, the controlling-solenoid circuit, and the brake-solenoidcircuit. This latter circuit is used when the motor is applied to elevator work where a friction-brake is used to stop the motion and the brake is released by a solenoid. In the armature-circuitis included the solenoid M, lever D, resistances at B or G or such portion of them as is not cut out by the contact-fingers Z) and lever D, resistances at B or C or such portion of them as is not cut out by fingers Z7 and lever D, and the series winding of the motor with the armature. In the shunt field-circuit is included the shunt field-winding of the motor, one or more of the segments 6 to 10, the finger c lever D, and the series field-winding, and when the lever D is at its middle position or on any of the three central segments it also includes one or more of the resistance-coils t. The controlling-solenoid circuit has two branches, one of which includes the winding of the solenoid K and one end segment of the series of segments 0, whatever resistance there is between this segment and the contact-point of the lever N, lever N, wire m, and when there is excessive load also part or the whole of resistance R. The other branch of the solenoid-circuit includes winding of the solenoid K, the end segment at the other end of the series of segments 0, whatever resistance there is between the end segment and the contact-point of the lever N, the lever N, wire m, and when there is excessive load also part or the whole of resistance R. The brakesolenoid circuit includes the winding on solenoid M, the hub of lever D, one or the other of lovers E or E, one or the other of the segments 1 2 3 4 5, and the winding of the brakesolenoid.

The operation may be described as follows: When the lever N is in its middle position, a very weak current is admitted equally to both solenoids K and K through the very high resistance of the coils located at the center portion of the series of segments 0. When the motor is to be started, the lever N is moved to one extreme of the series of segmentssay to the right. This removes all resistance from the branch circuit of solenoid K, and this solenoid then pulls its core J upward and this causes the lovers D and D to move toward the right. WVhile these levers are in the central position, all the resistance at B, O, B, and O is in the armature-circuit and allows only a very feeble current to flow through the resistances and none through the armature. When the levers D and D arrive at the extreme end of the series of segmentsfor instance, to the rightall resistance is cut out and the armature-circuit receives its full current, said current passing through wires 13 14 15 and thence through the lever D. The movement of the levers to the right is retarded by the dash-pot L, and thus the current is admitted gradually to the armature, which is caused to rotate, the shunt field-circuit being energized to its full extent as soon as finger c arrives at segment 10, which is considerably before the levers D and D reach their limit. The current comes from the plus-pole by wire 18 through the shunt-winding, wire 1 segment 10, finger c lever D, wires 16 q, series-winding, wire q, and thence to negative pole. To stop the motor, the lever N is brought to central position, solenoid K becomes weakened and equal to solenoid K, so that the spring on rod S brings the levers D D back to central position, where the armature gets no current. To start the motor in the reverse direction, the lever N is turned to the other extreme end of its range, where it cuts out all resistance from the circuit of solenoid K. This solenoid then draws up its core J and moves the levers D D to the left, and the movement is retarded by the dash-pot L. Current is thus admitted to the armature in a reverse direction and gradually brought to full strength. The current passes down lever D, wire 14, through the armature, wires 13 17, through lever D, duo. \Vhen the lever N is brought to the center, solenoid K loses its force and becomes equal to solenoid K, and the spring on rod S brings the levers D D back to the central position. After the motor is started if it is desired to change its speed this may be done by proper manipulation of the lever N, which the operator soon becomes accustomed to. By moving the lever N to intermediate positions the relative strengths of solenoids K and K may be nicely adjusted, so as to make the levers D and D take up intermediate positions, and thus introduce more or less resistance into the armature-circuit. admitted too rapidly to the armature-circuit for the safety of the motor, the solenoid M acts to check it by inserting the resistance R, weakening the solenoid K and K, whichever one happens to be in action, and thus allows the levers D D to come back to some position nearer the center, where the current will be reduced to proper limits. The current in the armature-circuit really undergoes a division through the resistances B, O, B, and C. When the levers D D are central, there is a very feeble current flowing through the resistances B O B 0 directly across from lever D to lever D and none through the armature.

I claim 1. In a controller for electric motors, the combination with the armature of a pair of differential rheostats each terminal of each rheo- If for any reason current is stat being connected with one armature-terminal, a rheostat-arm for each rheostat and means for operating said arms in unison with each other.

2. In a controller for electric motors, the combination with the armature of a pair of differential'rheostats each terminal of each rheostat being connected with one armature-terminal, a rheostat-arm for each rheostat, a connecting-rod connecting the two arms and means for operating said arms.

3. In a controller for electric motors, the combination with the armature,ofapairofdifferential rheostats each terminal of each rheostat being connected with one armature-terminal, a rheostat-arm for each rheostat, a connecting-rod connecting said arms, a pair of solenoids, each adapted to throw said arms in opposite directions.

4. In a controller for electric motors, the combinationwith the armature,ofapair of differential rheostats each terminal of each rheostat being connected with one armature-terminal, an inverted- L-shaped rheostat-arm for each rheostat, a connecting-rod connecting said arms, a pair of solenoids connecting with the horizontal portion of said arms.

5. In a controller for electric motors, the combination with the armature of a pair of differential rheostats connected with the armature, a pair of connected rheostat-arms for said rheostats, a set of segments adjacent to one of said arms, a contact-finger on said arm adapted to slide on said segments, said segments being connected with the shunt-wind ing of the motor and said rheostat-arm c0nnecting with the line-terminal.

6. In a controller for electric elevator-motors, the combination with the armature, of a pair of differential rheostats connected with the armature, a pair of connected rheostatarms for said rheostats, a set of segments adjacent to one of said arms, a contact-finger on said arm adapted to slide on said segments, said segments being connected with the brakesolenoid and thence to one pole of the line and said rheostat-arm being connected with the other pole of the line.

7. In a controller for electric elevator-motors, the combination with the armature, of a pair of difl'erential rheostats connected with the armature, a pair of connected rheostatarms for said rheostats, a set of segments adjacent to one of said arms, a pair of auxiliary arms adj ustably connected with said rheostatarm, contact-fingers on each of said auxiliary arms adapted to slide on said segments, said segments being connected with the brakesolenoid and thence to one pole of the line and the rheostat-arm being connected with the other pole of the line.

8. In a controller for electric motors, the combination with the armature, of a pair of differential rheostats each terminal of each rheostat being connected with one armatureterminal, a pair of connected rheostat-arms for said rheostats, a pair ofsolenoids for operating said arms and a spring for holding said arms in their central or normal position.

9. In a controller for electric motors the combination of a pair of difierential rheostats connecting with the armature, a pair of connected rheostat-arms for said rheostats, one of said arms being connected With one line-terminal, a pair of solenoids for operating said arms, solenoid-circuits connecting the lineterminals with said solenoids, an emergency-rheostat in said circuit, a solenoid for operating said rheostat in the circuit between said rheostat-arms and the line-terminal, the emergency-rheostat being adapted to throw resistance into the solenoid-circuit when there is an excess of current passing through the main rheostat-arm and means for controlling the solenoid-circuit.

I 10. In a controller for electric elevatormotors, the combination of a pair of differential rheostats connected With the armature, a pair of connected rheostat-arms for said rheostats, a set of segments adjacent to each of said arms, one set connected to the brakesolenoid and the other connected with the shunt-Winding, contact-fingers operated by said arms adapted to slide on said segments, a pair of solenoids for operating said rheostat-arms, circuits for said solenoids connecting with the line-terminals, a spring for bringing said arms to their central or normal position, an emergency-rheostat and an emergency-solenoid operating the same, the resistance in said emergency-rheostat being included in said solenoid-circuits, means for Varying the solenoid circuits, one of said rheostat-arms being connected with one lineterminal through said emergency-solenoid and the rheostat-arm being connected with the other terminal through the series Winding of the motor.

Signed at Portland, Maine, this 6th day of March, 1902.

WVILLIAM H. CHAPMAN. Witnesses:

S. W. BATES, HARRY E. Ross.

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