US728814A - Device for automatically cutting out starting resistances of electric motors. - Google Patents

Description

No. 728,814. PATENTED MAY 19, 1903.

G. H. WHITTINGHAM. I DEVICE FOR AUTOMATICALLY CUTTING OUT STARTING RESISTANCES OI ELECTRIC MOTORS. APPLICATION FILED JULY 8, 1902. RENEWED APR. 15, 903.

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UNITED STATES Patented May 19, 1903. PATENT OFFICE.

GEORGE HERBERT WHITTINGHAM, OF NEW YORK, N. Y., ASSIGNOR TO AUTOMATIC SWITCH COMPANY OF BALTIMORE CITY, A CORPORA- TION OF MARYLAND.

DEVICE FOR AUTOMATICALLY CUTTING OUT STARTING RESISTANCES OF ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 728,814, dated May 19, 1903.

Application filed July 8,1902. Renewed April 15, 1903. Serial No. 152,801. (No model.)

To (tZZ whmn it may concern.-

Be it known that I, GEORGE HERBERT WHIT- TINGHAM, a citizen of the United States, residing at New York, State of New York, have invented certain new and useful Improvements in Devices for Automatically Cutting Out Starting Resistances of Electric Motors, of which the following is a specification.

This invention relates to improvements in automatic starting devices for electric motors, which have for-their object to gradually reduce the resistance in the armature-circuit of the motor automatically when the current is turned on and the motor starting by cutting out the coils of resistance one after the other from that of the greatest resistance to that of the least resistance and maintaining it in this position during the running of the motor, so that when the circuit through the motor is first completed to start the motor the current will meet with the greatest resistance and when the motor is fully running there will be the least resistance to the passage of the current. When the current is shut ofl', this controlling device operates to automatically replace the resistance in the circuit in readiness to be started again.

The object of the invention is to provide an improved device of this character in which a clutch device driven directly or indirectly by a motor moves the contact for the starting resistance from the point of high resistance toward the point of low resistance and automatically releases said contact at a desired point, thereby throwing the clutch entirely out of service and relieving it from any further work or undue friction while the m0- tor is running.

Reference is to be had to the accompanying drawings, in which Figure 1 is a diagrammatic view illustrating one arrangement in which the principles of the invention may be carried out, and Fig. 2 is a detail transverse sectional view of the clutch device employed in the present instance merely for the purpose of illustrating the invention.

Referring to the drawings, Fig. 1, the letter a designates an electric motor; b, an electromagnetic clutch device; 0, the starting resistance for the motor, and d a switch of any suitable construction adapted to open and close the line-circuit. The shunt-field of the motor a, is energized by a Wire 6, secured to one side of the switch d and extending therefrom to a binding-post or similar connecting-point f, and also by a wire e, extending from. said post f back to the other side of said switch. Also to the post f, as illustrated in Fig. 1, is secured a Wire 9, passing to a pivot-post h, and from thence through the helix 2' of the electromagnetic clutch device b to one end of a helixj, coiled around a soft-iron core 70, and forming with said core a retaining-magnet Z, whose purpose will be presently described. One end of the winding ofsaid helixis connected directly to orgrounded on the iron of the magnet-core k, and the other end of said helix is secured to a Wire m, which passes through a permanent resistance n back to the line-circuit.

/ The starting resistance 0 is mounted on a suitable base, with its low-resistance end contiguous to the retaining-magnet l, and to said end is secured a wire 0, which passes through the motor-armature and joins atp the returnwire 6 of the shunt-field, so that it is connected to one side of the line-circuit, as illustrated.

The electromagnetic clutch device bin this instance comprises a cup-shaped disk q, provided on its periphery with teeth q, meshing with a worm r on the armature-shaft 'r, and said disk is mounted to rotate on an axis 3, rigidly secured to a base-plate s. The wire forming the helix 2' of the said electromagnet is wound around a spool t", rigidly supported on said base-plate s, and is located within said disk. A keeper t is also mounted on said axis 8 so as to turn thereon in either direction, and said keeper is in contact with the circular rim or face g of thedisk q, whereby it may be gripped by said disk when the latter is energized. To the free end of said keeper t is connected a link t, which in turn is connected to a contact-arm u, pivoted at one end to the pivot-post h and carrying at its other end a brush-contact adapted to sweep step by step over the contact-plates of the starting resistance 0 when the said arm is moved.

In practical operation when the line-circuit is closed the current flows in the direction of the darts, Fig. 1, from the line to the point f, where it divides and a portion flows through the shunt-field and thence back to the line. The other portion of the current flows from the poiutf to the pivot-post h, where it again divides, a portion thereof flowing through the clutch device to energize the same and thence back to the line through the retaining-magnet and permanent resistance, and the other portion thereof flowing through the contact-arm u,the starting resistance c,and thence through the armature back to the line. When the motor starts by the closing of the line-circuit, its armature rotates the disk (1 of the clutch device, which has been energized by the current just described and has therefore attracted and gripped to it the keeper t, and said rotation of the disk thus draws the contact-arm u upwardly, cutting out the starting resistance until the point of lowest resistance has been reached, at which point said arm abuts against the core of the retaining-magnet Z, thereby short-circuiting and deenergiziug the clutch device by making direct contact with the grounded end of the helix j of the retaining-magnet. Thus the keeper t is released, and the disk q is allowed to rotate freely, relieving said disk from any further work or undue friction while the motor is running. The magnet Z retains the contactarm u at the low-resistance end of the start ing resistance until the line-circuit is opened to stop the motor, when said arm moves back automatically to its starting position either by gravity or any suitable means, such as a spring e.

While in the accompanying drawings the clutch-disk q is shown in direct connection with the motor-armature, it is manifest that various intermediate connections may be substituted for said direct connection to effect the rotation of said disk. For instance, in elevator-service the winding-drum of the elevator might drive the said disk by means of a gear or chain, or the disk may be rotated entirely independent of the said motor.

While in the accompanying drawings is illustrated one method of deenergizing the magnet of the clutch device-namely, by short-circuitingit is to be understood that other methods also may be employed to accomplish this result without departing from the scope of the invention as defined in the appended claims.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent, is

1. The combination of a motor; a contact governing the admission of current to the motor; a clutch device actuated by the current to make connection with said contact; means for moving said clutch device whereby to move said contact and vary the strength of the current passing through the motor; and means for denergizing said clutch device to release it from said contact.

2. The combination of a motor; a contact governing the admission of current to the motor; a clutch device actuated by the current and driven by the motor to operate said contact and vary the strength of the current passing through the motor; and means for deenergizing said clutch device by the movement of said contact.

3. The combination of a motor; a contact governing the admission of current to the motor; a clutch device actuated by the current and driven by the motor to operate said contact and vary the strength of the current passing through the motor; means whereby at one point in its movement said contact will deenergize said clutch device so as to release itself therefrom; and means for returning said contact to its starting position.

4. The combination of a motor; a starting resistance for the same; a contact adapted to a cut said starting resistance in and out; a clutch device operated by the motor for moving said contact; and means for denergizing said clutch device and retaining the contact in the position it has reached when the clutch device is deenergized.

5. The combination of a motor; a starting resistance for the same; a contact for cutting said resistance in and out; a clutch device adapted to grip said contact by electromagnetic influence and driven by said motor to move said contact; and means for short-circuiting said clutch device whereby to deenergize the same and release it from said contact.

6. The combination of a motor; a starting resistance for the same; a contact adapted to out said starting resistance in and out; a clutch device operated by the motor for moving said contact; means for denergizing said clutch device; mechanism for retaining the contact when the clutch device is deenergized; and means for automatically returning said contact to its starting position.

7. The combination of a motor; an electromagnetic clutch arranged to be operated by the motor; a starting resistance and contactplates therefor; an arm adapted to contact with said plates; a connection between said arm and said clutch whereby the latter may move the former over said plates; and a retaining-magnet connected in series with the coil of the electromagnetic clutch and in a position to permit the arm to contact therewith whereby to short-circuit said clutch when the starting resistance has been cut out.

8. The combination of a motor; an electromagnetic clutch arranged to be operated by the motor; a starting resistance and contactplates therefor; an arm adapted to contact resistance has been cut out; and means for with said plates; a keeper adapted to be returning said arm to its starting position. I0 gripped to said clutch by magnetic influence In testimony whereof I affix my signature and connected to said arm; a retaining-magin the presence of two witnesses.

5 net connected in series with the coil of said GEORGE HERBERT WHITTINGHAM.

magnetic clutch and in a position to permit Witnesses: the said arm to contact therewith whereby to CHARLES B. MANN, J r.,

- short-circuit said clutch when the starting FREDERICK S. STITT.

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