US1419749A - Alternating-current motor - Google Patents

Description

T. J. MURPHY.

ALTERNATING CURRENT MOTOR.

APPLICATION FILED JUNE 2!, 1917.

1,41 9,749. ate ted J um: 13, 1922.

IN VEN TOR.

1720112415 J I? W H7 61 0 W Z&S A TTORNE;YS.-

WITNESSES:

UNITED STATES;-

PATENT OFFICE.

rnouas .1. MURPHY, or noonnsrea, NEW-YORK, ASSIGNOR or bNE-H-QLF 'ro .mmns

- an. DUFFY, or noonns'rnn, NEW YORK- ALTERNATING-CURRENT MOTOR.

Patented e 13, 1922.

Applicationfilcd June 21, 1917. Serial No. 176,221.

To aZZ whom it may concern:

Be it known that I, THOMAS J. MURPHY,

a subject of the King of Great Britain, re-

siding at Rochester, in the county of Monroe and State of New York, have invented cermotors and has reference particularly to a type of construction coming within the general class of induction motors, wherein there is provided a stator affording a shifting magnetic field, acting upona cooperating rotor, the movement of which is roduced by currents set up in it by the shifting magnetic field and reacting upon the field. The purpose of my invention is to provide a slow speed motor which "can be retarded,'speeded up, or reversed with great facility. Another object of the invention is to afford, a 'cheap construction, which is mechanically simple,

- so as to bring it within range of 'a large variety of applications where expensive motor installatlonsand up-keep 1s prohibitive. To these and other ends the invention "con sists in certain improvements and combina tions of parts, all as will be hereinafter more fully described, the novel features being pointed out in the. claims at specification. p In the drawings: q

Figure 1 is a sectional viewillustrating one application of the invention, as an example of its possible uses, and I Figure 2 is a horizontal sectional view of Figure 1, largely diagrammatic, and illustrating the arrangement of circuits.

Similar reference characters throughout I the several views indicate the same parts.

The invention may be carried out in a number of different ways and is susceptible of adoption 'fOI' Il11IIlel011S purposes, and I have illustrated by .wayof example one of its large fields of usefulness, in the driving operation of a record support or table in sound or music reproducing apparatus. In such instances, the motor can readily be designed for a speed such that no reduction gearing is necessary, the record beingdriven the" end of the at the same speed asthe rotor. The present structure eliminates the objectionable noise incidental to other forms of electrically driven sound reproducing apparatus, and moreover presents an exceedingly economical arrangement which can be easily adjusted to suit changing requirements.

In the embodiment illustrated, 1 designates a stationary base or support upon I which the field magnets are mounted, while 2 is a frame or spider which carries the rotor and is fixedupon a spindle 3 journaled-in a socket 4 of the base 1. The rotor consists of a relatively thin plate of diamagneticmaterial such as copper or aluminum, ref: erably 1n the form ofa ring or annu us 5 which is carried [upon the frame 2. In the present instance, the latter also constitutes the table or support-for a disc record of a sound reproducing apparatus, although this disposed 'uponopposite sides of the rotor and in close proximity to its opposite surfaces; The field magnets 6 may be laminated and radially slotted and are adjustable with referenceto each other, but normally disposed in staggered relation to each other so that the teeth or'projections of one magnet are directly oppositethe winding spaces orTslots of the-opposite magnet. To this end the outer magnet is held in place by the bolts 7 cooperating with slots 8 so that by moving the bolts lengthwise of the slots,-

the outer stator unit or field magnet can be brought into varying relation with the inner or opposite magnet, and under ordinary operating conditions, one magnet is positioned with reference to the other substantially as shown in Figure 2, the purpose of which will appear in a moment.

With the parts arranged as described, alternating current is fed to the field magnets, so as to present the maximum intensity first upon one side of the rotor and thereafter upon the other side, through the alternating poles, and the current set up in the rotor reacts upon the field magnets. in such a way as to have imparted to it a series of successive impulses producing a continuous movement. To effect this, there is produced a difference in phase of magnetic flux from the two field magnets, and this may be accomplished in different ways. As an illustration of one efficient method of accomplishing it, I have shown a resistance element which is non-inductive and arranged in parallel acrossthe circuit leading to one of the field magnets. The circuit is designated generally at C, being supplied from any suitable source of alternating current, which passes b conductor C to the outer field magnet, tfience by conductor C to the resistance element R and to the inner field magnet, and from there through conductor C to the other side of the line. Thus the phase of the current in one magnet is dis placed with reference to that in the other, so that in passing through the one magnet it lags somewhat behind the other. This may also be accomplished by employinga twophase current for the different magnets, or by using ferric'metals of different hysteresis losses for the inner and outer magnets. Also the windings may be different on the inner and outer magnets, to increase the difference in phase of the magnetizing current, or one magnet may be provided with greater self induction than the other, as by partially or entirely closing the radial slots at the outer edge.

motive power, the statormay include com- And to obtain increased plete rings, instead of segmental magnets as herein shown. v

By adjusting the outer field magnet with reference to the inner one, the speed of the rotor can be reduced until the poles of one magnet are exactly opposite the polesof the other, at which point no movement will take place and if the adjustment is carried still further, the effect is to move the rotor in the opposite direction from its previous direction of travel and thus reverse the motor. By the adjustment of the outer field relative to the inner if the electrical phase dis placement in the inner and outer windings be regarded as constant then the synchronous speed of the motor is changed.

I claim as my invention:

1. An induction motor comprising an an nular rotor, field magnets disposed on opposite sides thereof having cores of metals characterized by different hysteresis losses for producing a shifting field, and adjust able means for varying the relative positions of said magnets and thereby controlling the speed of rotation of said rotor.

2. An induction motor comprising a rotor movable between oppositely arranged field magnets, the magnets on opposite sides of the rotor comprising laminae of metals having different hysteresis losses.

THOMAS J. MURPHY.

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