US663207A - Means for starting or stopping electric motors. - Google Patents

Description

No. 663,207. Patented flec. 4, I900. .1. J. WOOD.

MEANS FOR STARTING 0R STOPPING ELECTRIC MOTORS.

(Application filed July 11, 189a) (No Model.) 2 SheetS-Sheet FIG, 2.

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No. 663,207. Patented Dec. 4, I900.

MEANS FOR STARTING 0R STOPPING ELECTRIC MOTORS.

(Application 'mad July 11, 1899.) (No Model.) 2 Sheets-Sheet 2.

WITNESSES: INVENTOR:

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THE NORRIS PETERS co. PHOYO-LWHQ WASHIN GGGGGG c UNITED JAMES- J. WOOD, OF FORT l/VAYNE, INDIANA.

SPECIFICATION forming part of Letters Patent No. 663,207, dated December 4,1900.

Application filed July 11, 1899. Serial No. 723,498. (No model.)

To all whom it 711,041 concern:

Beit known that I, JAMES J. VVOOD,a citizen of the United States, residing at. Fort Wayne, in the county of Allen and State of Indiana, have invented certain new and useful Improvements in Means for Starting or Stopping Electromotors, of which the following is a specification.

This invention provides an improved starting box or rheostat for use in starting electromotors and adapted to break the circuit and stop the motor in case either of a cessation of the current or of an overload of the motor. According to my invention 1 provide the starting-box with a double-pole switch and provide means for operating this switch in connection with a rheostat and controllingmagnet in such manner that upon' no load occurring the entire resistance of the box is first thrown into circuit and immediately thereafter the double-pole switch is thrown,

' therebyautomatically, safely, and effectively breaking the circuit and preventing injury to the motor.

My invention also provides a single controlling-magnet in place of the two magnets heretofore usednamely, the shunt and overload magnets.

My invention provides also other features of improvement which will be hereinafter fully set forth.

Figure 1 of the accompanying drawings is a front elevation of my improved starter in its preferred form, showing it in the position occupied while the motor is running under normal conditions. Fig. 2 is a vertical section of Fig. 1, taken approximately on the line 2 2 therein. Fig. 3 is a horizontal section thereof, taken approximately on the line 3 3 in Fig. 1. Fig. 4 is an elevation similar to Fig. l in the position for starting, showing (liagrammatically the electrical connections. Fig. 5 is a fragment of Fig. lon alarger scale and showing the controlling-magnet in section. Fig. 6 is a similar view to Fig. 5, showing the operation of releasing by a cessation of the current-flow. Fig. 7 is a similar view showing the operation of releasing by an overload. Fig. 8 is a plan of the controlling-magnet, its lever being omitted. Fig. 9 is a side elevation of the controlling-magnet viewed from the loft; in Fig. (i. Fig. ldisafragmcntary sectional view of the actuator for the double-pole switch looking from the front in section on the line 10 10 in Figs. 3 and 11. Fig. 11 is an oblique section thereof on the line 11 11 in Fig. 10. Fig. 12 is a sectional elevation of a detail of the controlling-magnet, and Fig. 13 is a transverse section thereof on the line 13 13 in Fig. 12. Fig. 14 is an elevation viewed from the right of the bracket and nut in Fig. 12. Fig. 15 is a fragmentary view showing a modification.

Referring to the drawings, letA designate the base or front plate of the starting box or rheostat, of which a a are the contact segments or terminals of the resistant coils, and B is the contact-arm, which swings over the series of segments, turning around a central stud O and formed, as usual, with a-suitable handle and with a contact spring or plate Z). The contact-arm B is formed with a short arm 3, which in normal use is engaged by the controlling-magnet or magnetic detent D, thereby holding the arm in the position shown in Fig. l, and it has another short arm B to which is connected asuitably-stiff spring E, the opposite end of which is attached to a suitable fixed point 0 on the base A, the effect of this spring being upon the release of the contact-arm by the controllingmagnet D to throw the arm across the series of contacts to the position shown in Fig. 4., and thereby cut in the resistance of the entire series of coils, which coils are indicated diagrammatically at (Z d in Fig. 4.

Mounted upon the plate A is a double-pole switch F of any suitable or usual construction, which in the construction shown consists of two conducting-blades ff, pivoted to circuit-terminals cc, to which are connected the main-circuit wires to to, Fig. 4, and the upper ends of which are coupled together by an insulating-bar g, to which is attached a handle F. When the switch is closed, as shown, the upper ends of the bladesffenter into forked contacts h h, respectively. These contacts are connected, as shown in Fig. 4-, the former to a bindingpost 20, which connects by a wire 21 to one terminal or brush of the motor, while the opposite terminal thereof connects by wire 22 to bindingpost 23, which is connected by wire 24 to the terminal contact-segment a of the series of segments a, while the opposite contact-piece h connects by wire 25 to the winding or coil I'L- of the controlling-magnet D, the opposite terminal of this coil being connected by wire 26 to the pivot 0, upon which the contactarin B turns. This pivot G is also connected by a wire 27 to a binding-post 28, to which is connected the shunt-wire29, leadingto one terminal of the field-magnet coil 30 of the motor, the opposite terminal of which connects by wire 31 to the wire 21. The motor shown in Fig. 4 (designated as a whole by the letter M) is of the shuntwound type.

hen the double-pole knife-switch F is thrown down, it of course breaks the main circuit to to. For thus throwing it down automatically I provide a switch-actuator G. (Best shown in Figs. 2, 10, and 11.) This consists of means .for throwing out the switch F clear of its contacts h h, which means is actuated by the contact-arm B when the latter swings over under the impulse of its spring E to the position shown in Fig. 4. The switchactuator G is therefore a sort of kicker for imparting an outward or forward thrust to the switch F upon being itself struck by the arm B when the latter has traveled home. Obviously the simplest construction of such kicker would be that of an elbow-lever, as shown atj in Fig. 15, being pivoted at j and arranged to be struck at one side by the arm B as the latter flies over and adapted to communieate this blow in an outward direction to throw the switch F forward. The simple modification thus shown is within my invention,bu t is practically inferior to the preferred form, which is best shown in Figs. 2, 10, and 11. In this preferred form I provide a pushrod or plunger 70, seated against a stiff spring m and which on being pushed back to the position shown in Fig. 2 is caught by a detent or small catch-lever Z, suitably pivoted and pressed into engagement by a small spring Z. The forward arm of the catch Zis arranged against a thrust-pin n, which slides freely in a standard or stop a and the upper end of which is arranged to be struck by the lever B, so that the blow of the latter is transmitted through the pin 02 to the catch Z to tilt the latter and release the plunger is, which thereupon is forcibly projected forwardly by the spring m, and thus energetically pushes forward against the switch-bar g, and consequently throws the switch out and breaks the circuit. In order to form a suitable mounting for the parts Z m, I preferably provide a small cylindrical casing or shell p, seated in a hole in the base-plate A and having screwed upon its rear end a cap 19, the plunger 7t and spring 071 being placed within the cylindrical cavity of this shell and the catch Z being pivoted in a slot cut in the side thereof. In order to cushion the blow struck by the arm B against the standard '11, I provide the latter with a cushion o, of yielding material, preferably soft vulcanized rubber.

I will now describe the preferred construction of the controlling-magnet or magnetic detent D with reference particularly to Figs. 5 to 9, inclusive. This magnet is constructed with a central core q and with top and bottom plates *1" 9', these latter being preferably cast and formed with feet resting against the plate A and fastened thereto by screws, as shown in Fig. 8. The plates 0* r constitute the pole-pieces of the magnet, and between them the coil or winding 1' is wound around the core g. with a groove or channel 1', through which the inner end of the winding 2' may be led by being preferably passed through a hole in the plate A. The armature H extends between or bridges the pole-pieces outside of the coil, so that its lower end comes adjacent to the lower pole-piece 1', while its upper end approaches the upper pole-piece r. This upper pole-piece is preferably bifurcated, as shown in plan in Fig. 8, and the upper end of the armature is preferably reduced in width, as shown in Fig. 9, so as to enter Within the bifurcation. The adjacent walls of the bifurcation are preferably made inclined, as shown in Fig. 8, so that as the upperend of the armature is attracted toward the core it enters into a narrower portion of the bifurcation and shortens the magnetic gap. Preferably the armature is provided with pins or pegs s, of non-magnetic material, projecting slightly from its sides at its upper end to prevent metallic contact be tween the armature and the poles or bifurcations of the pole-piece r, and at its lower end it; has similar pegs or projections s to prevent actual metallic contact between itand the lower pole-piece r. is pivoted at LE in a lever I, which is forked, as best shown in Fig. 3, its forked arms extending laterally outside of the pole-piece r and being fulcrumed thereto at w and being thence extended downwardly to the pivots w, by which the armature H is hung to the lever. The main or undivided part of the lever extends horizontally over the top of the magnet and has attached to it a spring 1, which exerts a downward tension against it, normally holding it down in the position shown in Figs. 5 and 6, with its stop projection r resting on the pole-piece 0'. For adjusting the tension of the spring t I connect it to a sliding rod t, movable in a tubular bracket 71/, which is fastened to the lower pole-piece 7", the lower end of this rod being screw-threaded, as shown in Fig. 12, and having an adjusting-nut it screwing upon it, by means of which to draw it down. To prevent turning of the rod, it is provided with a pin 1?, which projects out through a vertical slot; n in the tubular portion of the bracket 1/. (Shown in Figs. 12 and 13.) Theend of this pin is turned down and pointed to form a pointer which traverses a scale marked on the exterior of the bracket it, as shown in Fig. 5. To prevent the nut u from turning acci' dentally, it is formed with a projection in, which at each half-revolution enters a notch The upper pole-piece 1- is formed The armature u, as best shown in Fig. 14, being held therein by the tension of the spring 15, a half-turn of the nut to giving the minimum of variation in tension that is desirable, although, if desired, the projections 7L3 and notches 10 might be multiplied so as to engage at intervals more frequently than each half-turn.

To the upper end of the armature is fixed a small catch-plate, one end of which overhangs at v, constituting a tooth for engagement with the end of the arm B to which arm also is 3 fastened a catch-plate o. These plates h o are beveled at their ends, so that as the arm B descends its plate will press toward the right. The upperend of the armature and the plate 1; will pass beneath the plate Q) to the position shown in Fig. 5; but upon the upper end of the armature being moved toward the right the plate or tooth o is removed out of engagement with the plate 1), thereby releasing the arm B and permitting the latter to fly upward, as shown in Figs. 6 and 7. This movement of the armature toward the right may be caused in either one of two ways namely, first, by the cessation of the current through the magnetic coil, whereby the lower pole-piece r ceases to attract the lower end of the armature and the latter flies up under the upward pressure of the arm B, the armature turning around its pivot 50, as shown in Fig. 6, thereby releasing the arm, or, second, by the current in the magnet-coil being augmented to the point where theincreased mag-- netism of the magnet draws the upper end of the armature from its normal position, Fig. 5, toward the right to the position shown in Fig. '7, in which case the armature swings around its lower pegs 3', its pivot 00 moving toward the right,and thereby tilting the lever I around its fulcrum 0c, and hence lifting the long arm of the lever against the tension of the spring t, as clearly shown in Fig. 7. The extent of augmentation of the current necessary to accomplish this result depends upon the tension of the spring t, and this in turn upon the adjustment given to this spring by the nut a, which is shown by the position of the pointer t against the scale. By means of this adjustment the extent of overload necessary to actuate the magnet may be varied at will within certain extreme limits,so that the same starting-box may Without other change than the alteration of this adjustment and perhaps in some cases the substitution of resistant coils d of greater or less resistance be adapted for the starting and stopping of motors of widely-different energyas, for example, for those varying from one-horse power or under to five-horse power, as denoted by the gradations on the scale in Fig. 5.

I will now explain the operation. Before starting the switch F is of course dropped to its lower or open position and the arm is in the position shown in Fig. 4, with all the resistance-coils cut. in. In order to start the motoiythe operatorfirst throws up the swi tch F, whereupon its cross-barg strikes the plunger 7t and presses it back until caught by the detent or or ch-lever Z. This closes the circuit, the current flowing to the motorfield-coil 30 from the contact 77, by the route 21. 31 29 28 27 26, magnet-coil i, and to the opposite contact It, thus exciting the motor-field and energizing the detent-magnet D. At the same time a small current flows through the armature of the motor against the resistance of the entire series of resistance-coils (Z (Z, this eurrentbeing sufficient to start the motor, and traversing the following path from contact hnamely, 2O 21 22 23 24, resistance-coils d d, arm B, 26, magnet-coil i, and 25to contact It. When the motor starts, the operator throws the contact-arm l3 over to the right, being resist-ed in this movement by the spring E, this movement successively cutting out the resistance until when the motor is up to full speed denergized and releases the lower end oft-he'- armature H, which swings out, as shown in Fig. 6, thereby releasing the magnetic detent and freeing the arm B, which under the impulse of the spring E at once flies over to the left, or in case the motor becomes overloaded or through any cause receives a dangerous increase of current the magnet I) then acts as an overload-magnet, and by the increase of its magnetism sulficiently to overcome the pull of the spring 25 its armature is attracted in manner shown in Fig. 7, thereby also releasing the arm B and permitting the arm B to fly over to the left under the action of its spring E. In either case the arm B strikes a blow through its cushion 0 against standard a, which stops it, and upon the pin n, which transmits motion to the catch 7, which releases the plunger k, and the latter is projected by its spring on forcibly forward, thereby thrusting or kicking the switch F forward and throwing down this switch, so as to simultaneously break both sides of the circuit. Anydangerous sparking at the motor or switch contacts is prevented by the action of the arm B in cutting in the entire resistance of the rheostat before the circuit is stop the motor the operator has only to pull up on the IGVGII, for which purpose its outer On pullingit up end is formed as a handle.

IIO

to the position shown in Fig. 7 the armature is moved in the same manner as if by an overload, and the arm B is in like manner released.

By my invention I accomplish with a single controlling-magnet D and single armature what has most ordinarily heretofore required two magnets ora magnet with two armatures namely, a shunt-magnet operating to break the circuit in case of a cessation of the current and an overload-magnet acting to break the circuitin case the current becomes excessive. I am able to utilize one magnet to accomplish both functions byconstructing it to hold the rheostat-arm during the limits of normal excitation and to release the arm under either extreme condition of minimum or maximum magnetization. The construction of the magnet by which this result is accomplished may be greatly varied within the limits of my invention. To this my invention adds the desirable capability of adjustment of the same apparatus'to ditferent powers, so that the same starting-box may be used with motors of differentsizes. To this end it is desirable that the minim um current which holds the armature H in position at minimum load should not vary or should not necessarily be altered for different sizes of motors, but that the maxim um current which determines the release of the arm and breaking of the circuit in case of an overload should be capable of operation according to the maximum load which the motor is designed to carry. This adjustment of the maximum currentis readily effected by the adjustment of the tension of the spring 25 by the means described.

1 construct the terminal cont-act a. of the rheostat preferably in the ordinary manner, so as to embrace the contactspring on both sides to insure a perfect contact, since the entire current passing through the armature traverses this connection. This of course introduces a frictional retardation,which tends to prevent the flying back of the rheostat-arm when released, and the spring E must be strong enough to start the arm against this retardation. On the other hand, it is desirable that when the arm is in the opposite position (see Fig. 4) it should be subjected to practically no tension from the spring. To these ends I so arrange and proportion the arm B and spring E that in the position shown in Fig. l the spring shall exert its maximum tension against the rheostat-arm sufficient to disengage it from the contact a, and from the moment of such disengagement the movement of the arm toward the left shall result in a progressive diminution of the effective tension of the spring, until in the position shown in Fig. at, the spring has lost all tension or imparts only sufficient pull to the arm to overcome the friction. Thus the disengagement of the switch-actuator G is due entirely to the impact of the arm 13, which strikes a hammer-blow amply su ftlcient to disengage the catch Z; but upon the restoration of this switch and the consequent rcsetting of the actuator no pressure is communicated from the arm 13 through the pin n to the catch Z sufficient to disengage this catch.

My invention may be variously modified without departing fromits essential features, which are set forth in the claims.

I claim as my invention in means forstarting, stopping, or controlling electromotors the following-defined novel features, each substantially as hereinbefore set forth, namely:

1. A starter for an electromotor comprising a rheostat and its arm, an electromagnetic detent for holding said arm in the normal running position, a switch, and an actuator distinct from said switch adapted upon being struck by said arm to open the switch.

2. A starter for an electromotor comprising a rheostat and its arm, a switch, and an actuator for said switch comprising a spring for throwing the switch open, and a catch normally restraining said spring, said catch ar ranged to be released by the movement of said rheostat-arm.

3. The combination with a switch of its actuator G, comprising plunger 70, spring m and catch 1, and the rheostat-arm B arranged to release said catch.

t. The combination with a rheostat and its arm, of a switch and its actuator, the latter operated by the impact of the arm as the latter reaches the position of maximum resistance and a spring for throwing said arm to the position for cutting in the resistance, adapted to exert its maximum tension against the arm when in the position of no resistance, and to progressively diminish its tension as the lever moves until at the position of maximum resistance the tension is practically ml whereby the mere tension upon the arm in such position is insufficient to move the actuator.

5. 'lhe-combination with a rheostat and its arm, having a contact frictionally embracing the arm in the position of no resistance, of a switch and its actuator, the latter operated by the impact of the arm as the latter reaches the position of maximum resistance, and a spring for throwing said arm to that position, adapted to exert its maximum tension against the arm when in the position of no resistance, and to progressively diminish its tension as the lever moves until at the position of maximum resistance the tension is practically ml.

(5. The combination with a rheostat and its arm, of a switch and its actuator, the latter comprising a spring for throwing the switch open, and a catch Z normally restraining said spring, and means for communicating motion from the rheostat-arm to the catch consisting of a pin 71, and a standard n for said pin adapted to serve as a stop for said arm.

7. The combination with a rheostat and its arm, the latter having a yielding cushion o, of a switch and its actuator, the latter comprising a spring for throwing the switch open, and a catch Z normally restraining said spring,

a standard 71. arranged to be struck by said cushion and a pin a for communicating the blow of said arm to said catch.

S. A starter for an electromotor comprising a rheostat and its arm, a double-pole knifeswitch, an actuator distinct from said switch for throwing it open, and means for operating said actuator upon the movement of said arm to the position for cutting in the resistance.

9. An electromagnetic detent comprising an electromagnet and armature, the latter arranged to bridge opposite poles of the magnet, and movable away from one pole upon a given diminution of magnetism, and movable toward the other pole upon a given increase of magnetism, and a spring arranged to oppose the latter movement and adjustable to vary the maximum magnetism to which said armature will respond.

10. An electromagnetic detent comprising an electromagnet and armature, the latter arranged to bridge opposite poles of the magnet, and movable away from one pole upon a given diminution of magnetism, and movable toward the other pole upon a given increase of magnetism, a spring arranged to oppose the latter movement, and an adjusting device for said spring comprising a pointer moving over a scale for indicating the maximum current to which said armature will respond.

11. An electromagnet comprising opposite pole-pieces, an armature bridging said polepieces, a lever to which said armature is pivoted between its ends, and a spring drawing said lever against a stop, whereby said armature is free to yield in one direction without tilting said lever, but in the other direction it can move only by tilting said lever against the resistance of said spring.

12. An electromagnet comprising polepieces 9" r", a lever I, an armature H pivoted to said lever, and having its ends approaching said pole-pieces, and a spring 5 pressing said lever to a stop.

13. An electromagnet comprising an armature capable of a double movement, a lever to which said armature is pivoted, a spring acting against said lever, and means for adjusting said spring.

14. An electromagnet having a spring '6, a rod t for adjusting said spring, a tubular bracket a through which said rod moves, a pin projecting from said rod and moving in a slot in said bracket to prevent the rod from turning, and a nut a screwing on said rod.

15. An electromagnet having a spring 15, a rod 15 for adjusting said spring, a tubular bracket a through which said rod moves, a nut a screwing on said rod, and means for pret'enting displacement of said nut, consisting ofinterlittingprojections and depressions formed at the abutting ends of said nut and bracket.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

JAMES J. WOOD.

Witnesses:

D. O. DAVIS, E. M. HULSE.

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