US445907A - Starting device for electric motors - Google Patents

Description

(No Model.)

B. P. SHARP STARTING DEVICE FOR ELECTRIC MOTORS. No. 445,907. Patented Feb. 3, 1891.

WITNESSES. F1641 INVENTOH.

46M Ta U NITED STATES PATENT OFFICE.

EDWUXRD PEARCE SHARP, OF BOSTON, MASSACHUSETTS.

STARTING DEVICE FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 445,907, dated February 3, 1891.

Application filed March 18, 1890.

To all whom it may concern:

Be it known that I, EDWARD PEARCE SHARP, of the city of Boston, county of Sulfolk, and State of Massachusetts, have invented certain new and useful Improvements in Automatic Rhcostats or Safety-Starters for Electric Motors, of which the following is a full and exact description, reference being had to the accompanying drawings, which form a part of this specification, and to the letters of reference marked thereon.

In the drawings, Figure 1 is an elevation comprising a general illustration of my improvements and their connections and relation to the motor. Fig. 2is a side elevation of electro-magnet 6, its armature '2', latch 7:, to. Fig. 3 is a corresponding endelevation. Fig. 4 is a side view in elevation of electromagnet (I. Fig. 5 is a corresponding end elevation. Fig. 6 is a side elevation illustrating the contact of arm f with the contact-plates g by means of its brushes m. Similar views are Figs. 7 and S, the construction therein being slightly varied in the matter of the brushes. Fig. 9 illustrates the winding up of the spring s by the movement of lever F in operating the switch. This is a substitute switch.

Like letters refer to the same or corresponding parts in all the figures.

The nature of my invention relates to the mechanism devised for controlling and graduating the amount of electrical current passing to the motor and indicating promptly an y inefliciency or failure of said control or graduating of the amount of electrical current, whether arising from accidental or other causes.

The invention consists in the employment of a rotary mechanism combined with a series of resistance-coils and contact-plates, whereby one after another of the resistances are cut out from a circuit until, when the motor is fully at work, the circuit becomes direct; also, in the employment of an electric lamp or other signal placed in or closely connected to the circuit, so as to be brought into action by any abnormal increase of electrical current, together with various devices, arrangements, connections, and combinations hereinafter more fully set forth.

The object, as already apparent, is to prevent or obviate the danger of injury to the Serial No. 344,402. (No model.)

motor and various parts and connections by any abnormal or excessive current.

Referring to the drawings, sis a spindle which carries the rheostat-arm f. This spindle is supported in any suitable bearings and is electrically connected to the binding-post t. The contact-plates g are arranged in a circle around spindle s, and each is connected to a resistance-coil r. The arm f is provided with a brush or brushes suitable to insure electrical connection between arm f and each contact-plate 9 while the arm f is passing over it in its rotary movement around the axis of spindle s.

The electro-magnets (Z and c are arranged conveniently for connecting substantially as shown, and are provided with suitable pivoted or movable armatures h and t. These armatu res have springs holding them or drawing them back out of contact or away from their respective magnets and against any suitable stop. The armature i is electrically con nected to post i, and is also held positively away from its magnet by means of a tilting latch is or equivalent device until the arm f in passing tilts it and so unlocks or unlatches the armature and leaves it free to be attracted to the magnet c. The armature 7L serves as a stop to arm f, preventing its rotary movement toward the left, as shown, until the magnet (Z becomes active and attracts it to itself, and so releases arm f. The resistancecoils are electrically connected from magnet c to magnet (I, and these, respectively, to binding-posts a and f. Armature is electrically connected to binding-post Z. An electrical lamp or other equivalent device susceptible to operation by means of an electric current passing through it is electrically connected to the line leading to the motor, as seen at binding-post r. This connection passing through the lamp is also connected to an armature b in movable relation to electromagnet a, said armature being pivoted similarly to 7L and 'z' and held by a spring away from magnet a against a suitable stop 0. Bindingpost to is electrically connected to uand c. Electro-magnet cl is connected to the line through bindingpost 00; also, as shown, to binding-post 1 The motor is connected, as shown, to posts i, g and w, and all parts of the mechanism not electrically connected of course should be properly insulated with respect to each other.

The springI have shown for operating with a circular movement the arm f by means of gearsis marked A. This spring may be wound up by an arrangement combining it with the swit'ch-lever'F.

For the purpose of illustrating the combination I have shown a substitute switch in Fig. 9. A glance at this view will make the operation apparent. WVhen the lever F is moved toward the observer to close the switch, the pawl E drags over the notches in the wheel connected with the springs barrel and is held up by pin B. On moving the handle reversely to open the switch the pawl takes hold, turns the wheel, and winds the spring.

The operation is as follows: The electrical circuit being. completed by the closing of the switch '0, it passes through magnet e and the resistance-coils r to magnet d, thence through binding-post t and line to motor, post y, coil a, post 00, and line. Magnet 01 thus becomes active and attracts armature h to itself, and so unlocks arm f, which begins to rotate, passing first to theleft. Coming into contact with plate g, connection is made through g, arm f, and spindle s to post i and the motor, cutting out magnet d and allowing armature h to be drawn back out of contact by its spring. The arm f, still moving on, comes in contact with plate g, by which contact plate 9 and its resistance-coil are cut out of the circuit. Arm f, still passing on around the circle, makes contact with plate g whereby plate g and its resistance-coil are cut out of the circuit, and so on until the arm f, making contact with g g", and g7, so leaves out of the circuit, successively each resistance-coil and comes in contact with and tilts the latch 75,

- so releasing armature t', Whichimmediately is current passes through coil and core of magnet c and armature 2' direct to t, and thence to the motorand the line. In case of any sudden stopping and starting of the current-as, for instance, in case of a break in the circuit on the linemagnet 6 will cease to be a magnet, and so allow armature i to be drawn out of contact by its spring, where it will be automatically held by latch is until again released by arm f, as described. If by anychance or otherwise the described operation has in any case failed, and an abnormal amount of electrical current is flowing through the motor, the magnet a will become active, and, according to the previous proper adjustment of the tension of springs, will draw armature binto contact with itself, (overcoming the said tension of spring .2.) Thecurrentis thus allowed to flow through armature b to and through the lamp 1 or equivalent electrical signal, so giving suitable notice or alarm,

The parts may be constructed of the materials common to the art or others suited to the described conditions and operations.

Any suitable power, as a spring or weight with suitable wheels and regulating device, may be used to rotate the arm f. I have shown a spring and ordinary clock-work.

I claim- 1. In a rheostat or starter for electric motors, the combination of magnet (Z in the line, its armature-releasing latch and stop h, the automatically-rotatory contact-arm carrying brushes, a circular series of contact-plates over which said brushes move with resistancecoils connected to said plates, the line-magnet 6, its circuit-closing armature 1', and latch 7c, operated by said contact-arm to release said armature i, so closing the short circuit, substantially as described.

7 2. The combination of the line-magnet (Z,

its releasing-armature 71, the automaticallyrotatory contact-arm, its brushes, contactplates, and resistances, line short-circuiting magnet and armature e 2', and latch 7c, operated by said contact-arm, substantially as described. i

3. The combination of the latch 75, armature i, magnet e in the line, the automatically-re. tatory contact-arm, and its series of contact-- plates and resistances for the purpose of shortcircuiting the current when the resistances are cut out, substantially as described.

4. The combination of the magnet din the line, its armature latch-and stop h for releas-.

ing and stopping the contact-arm, the automatically-rotatory contact-arm, its contactplates, plate contact -brushes, resistances, and the circuit-closing armature 'L', line-magnet e, and armature-releasing latch 7c, operated to close the short circuit by the contactarm, substantially as described.

5. The double-function hand-lever F, provided with contact-plate '0' and pawl E, in combination with the'contact binding-posts for connection to line and rheostat and the winding ratchet-wheel on the barrel or shaft giving motion to the rotatory contact-arm, substantially as described.

6. In a rheostat or starter for electric mo: tors, the combination of an automatically-rotatory contact-arm, a retaining armaturelatch h, a releasing line-magnet (Z, a circular series of contacts and connected resistances,

a short-circuiting latch-holder armature i, and'magnet c in the line, substantiallyas de-v Witnesses:

F. M. IIooPER, D. N. B. COFFIN.

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