US1309641A - David c - Google Patents

Description

D. C. LARSON.

ACCELERATING MAGNET.

APPLICATION FILED AUG.26.|916. 1,309,641 Patented July 15, 1919.

2 SHEETSSHEET 1.

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INVENTOR ATTORNEY Patented July 15, 1919.

2 SHEETS-SHEET 2.

D. C. LARSON.

ACCELERATING MAGNET.

APPLICATION FILED AUG.26. 1915.

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DAVID C. LARSON, OF YONKEBS, NEW YORK, ASSIGNOB. '10 OTIS ELEVATOR COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

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Specification of Letters Patent. Pat t d J 1 15 1919 Application filed August 28, 1916. Serial No. 116,972.

To all whom it may concern:

Be it known that I, DAVID C. LARSON, a citizen of the United States, residing in Yonkers, in the county of Westchester and State of New York, have invented a new and useful Improvement in Accelerating Magnets, of which the following is a specification. 4

.My invention relates to an improvement in accelerating magnets which control the speed of an electric motor by cutting in or out sections of resistance in the armature circuit of the motor.

Magnets of this nature are provided with a series of switch arms controlling sections of resistance in the armature circuit of themotor; these switch arms should operate in a certain predetermined order, of course, in order that, in bringing the motor up to speed for instance, by cutting out resistance in the armature circuit, too much resistance will not be cut out of the circuit at one time. I have rovided a magnet having means associated therewith which will prevent a wrong operation of the switch arms. I have shown by way of illustration four switch arms, each arm controlling a certain section of resistance, the first arm which goes in cuts out its section of resistance, and likewise each arm as it goes in cuts out its section of resistance, but with my arrangement until the first switch arm goes in the others cannot 0 in. By this arrangement the motor will ave been accelerated somewhat by the going in of the first switch arm, before any of the other arms can operate.

Referring to the accompanying drawings illustrating my invention, Figure 1 is a front elevation of the magnet, Fig. 2 is an end elevation of the magnet, Fig. 3 shows the magnet in use in an elevator system, and Fig. 4 is a modification of the apparatus of Fig. 3.

The magnet is secured to a support 2 outward movement. Secured to the arm 7 is a bar 24, this bar extending across the faces of the arms 8, 9 and 10, between them and the slate 1, so that these arms cannot be pulled in unless the arm 7 is first operated. The arm 7 carries at its upper end a back contact 25 which is adapted to engage a stationary contact 26 secured to the slate 1 by a support 27, when the arm 7 is in its outward position. It will be understood that the arms 7, 8, 9 and 10, may be set at varying distances from the core 28 of the magnet, so that it will take-more power to pull in the arm 8 than the arm 7, the arm 9 than the arm 8, etc., or they may be of varying increasing weights, for the same purpose.

I will now describe the operation of my device in connection with an elevator system, as. shown in Fig. 3. An elevator car. designated C, is adapted to 'be raised and lowered by an electric motor M, the speed of which is tobe controlled by my accelerating magnet. Reversing switches R and R are shown, to control the direction of current flow through the motor M, these switches being controlled by electromagnets E and E respectively; these magnets in turn being controlled by the hand switch S in the car, through contacts 28 and 28. As shown in Fig. 3, if the lever of the switch S in the car be moved to the left for instance on to the left hand contact 28, one of the electromagnets, the electromagnet E, will receive cur-rent from the main, through conductor 29, lever of the car switch S, left hand contact 28, conductor 30, through the winding of the electromagnet E, conductor 31, resistance 32, conductor 33, and out to The electromagnet IE will then raise its core 34 which is secured to the reversing switch R, and the contacts of the reversing switch will be closed. A circuit may now the traced through the motor, from the main, conductor 35, contact ion reversing switch R, 39, 40, conductors 41 of the motor M, through the motor, brush 44, conductor 45, contact 46, contact 47 of the reversing switch R, conductor 48, resistance sections 49, 50, 51, 52, and out The field'circuit of the motor may be traced from the main, conductor 35, contacts 36, 37, conductor 58, conductor 59, resistance 60, conductor 61, field 62, conductor 63, and out The circuit for the winding of the accelerating magnet is in shunt to the motor, and may be traced from the conductor 42, through conductor 64, magnet winding 20, conductor 65, conductor 45, brush 44, motor M, and brush 43 back to conductor 42. As the motor M starts to rotate due to the reversing switch R having been operated, it will generate counter-electro-motive force until the same is ufliciently high to pull in 'the arm 7 of the accelerating switch, and the circuit of the motor M due to the operating of the 36, contact 37 of the conductor 38, contacts and 42, brush 43 arm 7, will then be from the conductor 48,

through conductor 66, contacts 11, 16, conductor 67, and resistance sections 50, 51 and 52, and out through instead of as it originally was traced, through the conductor 48, and resistance sections 49, 50, 51 and 52. The motor will therefore accelerate. As it increases in speed the counter electromotive force will rise until the arm 8 will be pulled in, cutting out the resistance 50; two sections of resistance will now be cut out, the sections 49 and 50, and the motor will accelerate still further. The arms 9 and 10 are pulled in successively, cutting out the resistance sections 51 and 52 and the motor is brought up to full speed. It will be noticed however, that unless the arm 7 is first pulled in, the other arms 8, 9 and 10, must remain out by reason of the bar 24 which is in front of them. Therefore all danger of say the switch arm 9 being pulled in first thereby cutting out resistance sec tions 49, 50 and 51 at once, which would be injurious to the motor, is eliminated.

If when'the lever of the switch S is centered and the reversing switch R drops, for some reason the arm 7 of the accelerating magnet does not drop out, I have means whereby the reversing switch cannot 'again be operated until the arm 7 has dropped out. This means comprises the contacts 25 and 25 and resistance 68. 'VVhen the arm 7 is in, the contacts 25 and 25' are in engagement, and should the lever of the switch S be operated to start the motor, it will be found that not only do we have a circuit through the winding of the electromagnet E, but we have another circuit which is tapped off the conductor 31, passes through resistance 68 and contacts 25 and 25 and back to plus. This cuts down the current which would otherwise flow through R is the same in provided the windin of the electromagnet E to such an extent hat the magnet will not operate to raise its core to close the reversing switch The operation of the reversing switch principle as the operation of the switch R which has been described, the electromagnet E controlling its operation. In this case also the resistance 68 will cut down the current in the winding of the electromagnet E in the event of the arm 7 sticking in, and it will be impossible to startthe motor until the arm 7 has dropped. It will thus be seen that not only does this resistance 68, together with the contacts 25 and 25 prevent the motor stopped and then started up again in the same direction in case the arm 7 should not drop out, but it also prevents the motor bebeing run and mg run, stopped and then reversed unless the arm 7 has dropped out.

he operation of the mechanism shown in Fig. 4 is the same as that described in connection with Fi 3, exceptin that the circuit for the win ings of the e ectromagnets E and E controlling the reversing switches is arranged in a different manner. In this instance the circuit for the windings of these electromagnets is through the back Contact 25 of the arm 7 and through the contact 26. As the contacts 25 and 26 are never in engagement unless the arm 7 is out, it follows that the circuit for the windings of the electromagnets E and E cannot be closed unless the arm 7 is out. The advantage of this arrangement is the same as already pointed out in connection with the arrangement of Fi 3. i

What I c aim and desire to ters Patent of the United States is zl. The combination of a motor, means to start and stop the motor, resistance initially in the circuit of the motor, a plurality of arms for cuttingout said resistance in steps,

' means controlled by one of said arms simultaneously to release the other arms after the first arm has operated, and a second means carried also by said arm to prevent the operation of the starting means for the motor unless all the resistance is first in the circuit of the motor.

2. The combination of a motor, resistance initially in the circuit of the motor, an acceleratlng magnet receiving its power from the counterelectromotive force generated by the motor, a plurality of switch arms operated by said accelerating magnet and cutting out said resistance in steps to thereby accelerate the motor, said arms being ar-' ranged to be moved to operated position in a predetermined order, a bar secured to the first arm which is to be operated and projecting into the path of the other arms to tact carried by said tact engaged by said contact when the arm name to this specification in the presence 'of is moved to operated position, and a circuit two subscribing witnesses. closed by the engagement of sitid contacts with each other to prevent the closing of the DA LARSON 5 motor circuit until said contacts have been Witnesses: separated. Emms'r L. GALE, J r.,

In testimony whereof, I have @signed my JAMES G. Bm'lmm...

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