US1871893A - Short circuiter - Google Patents

Description

Aug. 16, 1932. E LARSH 1,871,893

SHORT CIRGUITER Filed NOV. 2l, 1929 ZIM/vento@ mmm. *93. Qwhm Patented Aug. 16, 1932 UNITED STATES PATENT ofi-*riesci ETTERE-TT P. LARSH, OF VANDALIA, OHIO, ASSIGNOR TO THE MASTER ELEGTRIG GOM- PLANY, 0F DAYTON, OHIO, A CORPORATION OF OHIO SHORT CIRCUITER Application led November 21, 1929. Serial No. 408,843.

This invention relates to electric motors and more particularly to a short circuiting or operation changing device for alternating current motors ot the repulsion induction type,rby which the motor is automatically changed from a repulsion starting condition to an induction running condition and vice-versa in accordance with variations of speed.

The present application is a continuation in part of copending' application Ser. No. '28,661 filed July 28, 1924, which has ma.- tured into Patent No. 1,779,006, wherein the present construction was shown and described as Figs. 9 and 10, but wherein claims to the present species could not be made because such application containsy claims to a different species.

The object of the invention is to simplify the structure as Well as the means and mode of operation of such circuit changing devices Whereby they will not only be cheapened in construction, but, Will be more etticient in use, automatic in operation, uniform 'i in action, automaticallyl controlled, and4 unlikely to get out of repair.

A `further object of the invention isto provvide improved means operated by centrifugal tendency by which the commutator, bars `f ai'e'automatically connected with a common electrical conductor Whichr Will promptly respond to variations of speed above and belovv a predetermined rate oi rotation.

` A further vobject off the 'invention is to provide means for controlling the movement of the short circuiting Aor current changing members whereby their movement lto ettect the alternation of the motor from repulsion to induction operation andv vice versa Will be eilected by a quick movement in either direction.

A further object of the invention is to 1novide suchy av short circuiting or current hanging device which will be compact, oit ien' parts, and having no pivot joints, nor

indirect movement, but in which the current co rolling devices are directly operated by ee i'tugal tendency.

With the above primary and other incidental objects in view, as Will more Jfully appear in the speciiication, the invention con# sists of the features of construction, the partsA vand combinations thereof, and the model of operation or their equivalents as hereinafter described and set forth in' the claims.

Referring to the accompanying drawing, Fig. l is a sectional view of a motor commutator and the short circuiting device forming the subject matter yhereof applied thereto. Fig. 2 is lany end elevation partly broken away of the shortcircuitin'g device" and commutator. F i0. 3 is an enlarged de-I tail View of the construction illustrated in. Figs. l and 2.v Fig. 4 is a similar' View ofr modification wherein the compressive Inov'e: ment upon the tension spring isv in opposite'v direction under the same' centrifugally actuI- ated movement of the Contact elements.

Like parts areY indicated by similar characr ters of reference throughout the several' views. v i

The structure of the electric motor per `se forms nofpart of the present invention, Which pertains Wholly to the short circuitin'gfmeanst for the commutator loa-rs, by which the motor is caused to operate alternately as a repul-Y sionmotor and'an induction motor! l,

An alternating current, repulsio'nnduci tion motor'oi' the single phase type to which the present invention is partcularlyadapted is one which, as the name indicates, starts'as" a repulsion motor andv as the speed' approaches its normal or maximum ratey of ro-` tation, automaticallyy changes its character and runs as an induction motor; `Briefly`de`l scribed it consists of a field or stator of laminatedl toothed construction having` ai single Winding thereon connected to the sup ply circuit and a progressively Woundar'rna# ture or rotor With a commutator engagedloyv brushes during the starting or rejiulsior7V period together Wit-h speed controlledide-; vices for short circuiting the armature Windi ings thru the commutator after the armaturehas attained a predetermined speed, Which speed controlled means in some instanceslift-s the brushes from the commutator simull` taneously with the short circuiting opera# tion; There is no electrical connection between the stator and the rotor. The currents in the stator create an alternating linx which reacts on the rotor and induces its rotation. This type of motor, therefore, starts as a simple repulsion motor, without compensating or auxiliary windings and operates as a repulsion motor until the rotor or armature approaches a synchronous speed, whereupon the speed controlled devices operate to automatically short circuit the arm ature winding through the commutator. Thus the motor is automatically transformed from a repulsion type into an induction motor having what is essentially a squirrelcage rotor. It is the improvement of the speed operated governing or short circuiting device which forms the subject matter of the, present invention. One of the advantages of a machine of this type is that it is inherently a constant speed motor having a high starting torque with low current consumption or minimum current surge.

The typical repulsion motor without compensation gives the most efficient starting torque possible while the single phase induction motor with the squirrel cage armature orits equivalent affords the most efficient motor when running.

A repulsion-induction type of motor comlbines these most desirable qualities in a single machine. As it possesses such high starting torque characteristics, it is well adapted for operating machinery which starts under kfull load, as pumps, air compressors, and grinding mills. Requiring no starter,

` they are adapted for automatic control or distance operation. They start quickly and operate quickly and smoothly.

The above is offered merely to facilitate a thorough understanding of the purpose of the invention, and with no intent nor desire that it shall in any way be construed as limiting or restricting the applica-tion or scope of the invention.

Inasmuch as the construction of the motor per se'forms no part of this invention, it has not been illustrated. It is to be understood however that the short circuiting means forming the subject matter hereoiE is applicable to various styles of motors of the character heretofore indicated. Referring to the drawings, 1 is the armature shaft on which is carried the usual commutator com- :face of the core 2. The overhanging portions of the commutator bars 3 may be variously shaped, either of rectangular form as shown in Fig. 3 or beveled as shown in Fig. 4.

The short circuiting mechanism comprises nsvreee an annular series of contact slugs or oscillatory arms 5, arranged approximately in parallel relation with the axis of rotation and with each other, and in proximity to the lateral face of the commutator. The inner ends of these oscillatory contact arms or slugs 5 extend within the recess formed by the projecting or overhanging ends of the commutator bars 3, with which the contact members make engagement upon out-ward or distended movement thereof. The contact members 5 are fulcrumed or otherwise mounted for oscillatory movement in a suitable mounting provided with al rest or stop limiting the retraction of such contact arms or slugs.

Such mounting in the present instance consists of a sleeve 10 surrounding the shaft 1 carrying a disc-like flange or collar 11 fixed* ly united with the sleeve 10. The marginal edge of the disc-like collar 11 is laterally flanged at 12 into overhanging relation with the outer ends of the oscillatory Contact arm 5. Slidingly mounted upon the sleeve 10 for aX- ial adjustment relative to the disc-like collar 11 is a second collar 13 which normally affords a support or rest for the contact elements 5ywhen in their inner or retracted position. A helical spring 14 surrounding the shaft 1 abuts at one end upon this sliding collar 13 normally tending to move the collar 13 away from the commutator and toward the fixed collar or disc 11. The spaced collars 11 and 13 afford therebetween a supporting or mounting channel having a laterally opening annular orifice or slot to receive the outer ends of the oscillatory contact arms. 5. The bearing portion 15 at the extremity of the arms 5 fulcrums within the seat formed by the lateral flange 12 of the kcollar 11. An inwardly extending finger 16 upon each of the oscillatory arms 5 affords a second bearing portion having operative engagement with the sliding collar 13. The arrangement is such that as the Contact arms 5 swing outwardly under centrifugal influence, they possess a leverage action, exerting a prying influence upon the sliding collar 13 tending to press such collar away from the fixed collar 11 against the yielding resistance of the helical spring 14e. Thus the helical tension spring 14 not only resists the axial movement of the collar 13, but through the engagement of such collar with the oscillatory contact arms 5, such spring 14 yieldingly resists the outward oscillation of such contact arms into engagement with the commutator bars 3, and tends to return the arms 5 to theirY when retracted, and a spring exerting its influence upon said annular sliding member aga-inst the tension of which said contact members are movable under centrifugal inrliuence into short circuiting engagement with the commutator bars.

2. The combination with a motor commut-ator and motor shaft, of an annular series of oscillatory contact arms engageable With the bars of the commutator under centrifugal iniiuence, contact arms being pivotally supported beyond the ends of the commutator bars and extending with their free ends in overlapping relation With said bars, .a pair of collars carried by the shaft, a sleeve fixedly connected with one of said collars upon Which the other collar is axially movable, a spring against the tension of which one of said collars is movable, said oscillatory arms having spaced bearing portions engaging the respective collars and exerting a prying action thereon tending to separate said collars against the yielding resistance of the spring as the contact arms move into short circuiting engagement With the bars of the commutator.

3. In a. short circuiting device for electric motors, the combination With a commutator having a series of oscillatory contact members arranged in annular formation concentric With the motor shaft and operable radially un der centrifugal infiuence into engagement with the commutator bars, a mounting sleeve upon the shaft, a fixed collar and a movable collar carried by said sleeve said fixed collar being located intermediate the movable collar and thexcommutator, a spring yieldingly resisting the movement of said collar, said oscillatory contact members beingfulcrumed upon the fixed collar and having operative engagement With the movable collar at one side of their fulcra by Which the collar axially shifted against the resistance of the spring upon movement of the Contact arms under centrifuga-l influence and having short circuiting engagement with the commutator at the opposite side of their fulcra.

Ll. The combination with a motor commutator and a motor shaft, of a series of oscillatory contact arms arranged in annular concentric relation with the motor shaft, a mounting therefor located beyond the extremiti es of the commutator bars from which the Contact armsV extend toward the commutator bars and into overlapping relation therewith comprising a sleeve surrounding the shaft, a fixed flange and an axially movable collar carried by the sleeve, a spring yieldingly resisting the axial movement of the collar, said contact arms having oppositely extending projections one of which has fulcrum engagement With the fixed flange, and the other of which has operative engagement with the movable collar upon oscillation of the contact arms tending to move said collar under centrifugal influence against the tension of said spring.

5. The combination With a motor oommutator and a motor shaft, of a short circuiter mechanism including an annular series of oscillatory contact arms arranged circumferentially of the motor shaft in offset axial relation With the commutator and operable radially by centrifugal influence into short circuiting engagement With the commutator, and a mounting therefor comprising a fixed collar surrounding the shaft the margin o-f Which is laterally flanged toward the commutator to form a fulcrum seat for said oscillatory arms, an axially movable collar located intermediate the fixed collar and the commutator, a supporting sleeve common to both collars, projections upon the arms engaging the movable collar as the arms move outwardly into engagement With the commutator, and a spring yieldingly resisting such movement of the collar and arms.

6. The combination With a motor commutator and a motor shaft, of an annular rseries of oscillatory centrifugally actuated Contact arms arranged concentrically of the motor shaft in axially offset relation with the commutator and extending toward thecommuta- 'tor and in overla inv relation With the extremities of the commutator bars, said arms being movable radially under centrifugal influence into engagement With the commutator, a mounting sleeve surrounding the shaft, va fixed collar and an axially movable collar carried by the sleeve, said fixed collar forming a fulcrum support for said contact arms and being located intermediate the movable collar and the commutator, said arms having abutting engagement With the movablev collar beyond their fulcra upon outward oscillatory movement, and a spring yieldingly resisting the axial movement of the movable collar and oscillatory movement of the arms.

7. The combination with a motor commutator and a motor shaft, of an annular series of oscillatory centrifugally actuated contact arms arranged concentrically of the motor shaft in axially offset relation With the commutator and movable radially under centrifugal influence into engagement with the commutator, a disc-like collar of sheet material surrounding the shaft in axially spaced relation beyond the ends of the commutator, the margin of Which is laterally projected toward the commutator, a sleeve surrounding the shaft with which the flanged discV collar is lixedly engaged, a second collar formed from sheet material surrounding the sleeve, laterally projecting flange on then second collar having sliding engagement upon said sleeve, and a helical spring surrounding the shaft and abutting at one end upon the movable collar and exerting pressure thereon in a direction away from the commutator, said contact arms being fulcrumed within the angle of said flanged disc collar and having abutting engagement with the movable collar whereby the oscillatory movement of the arms will be yieldingly resisted by the spring.

8. The combination with a motor commutator and a motor shaft, of an annular series of oscillatory centrifugally actuated contact arms arranged concentrically of the motor shaft in axially offset relation with the commutator and extending toward said commutator into overlapping relation with the ends of the commutator bars and movable radially under centrifugal influence into engagement with the commutator, a disc-like collar of sheet material surrounding the shaft, a sleeve surrounding the shaft with which the disc-like collar is fiXedly engaged, a second collar formed from sheet material surrounding the sleeve, a laterally projecting flange upon the second collar having sliding engagement upon the sleeve, and a helical spring surrounding the shaft and abutting f5 at one end upon said movablelcollar, said 5 shaft in axially offset relation with the commutator and extending toward said commutator into overlapping relation with the ends of the commutator bars and movable radially under centrifugal influence intoengagement with the commutator, a mounting sleeve carried by the shaft, a pair of spaced collars carried by said sleeve, said oscillatory contact arms having fulcrum engagement with one of said collars, and being sup- I ported in retracted position by the other collar, and a spring against the yielding resistance of which the arms are movable under centrifugal influence into short circuiting engagement with the commutator.

l0. In ank apparatus of the character described, a rotatable shaft, an annular series of centrifugally actuated oscillatory contacts arranged about said shaft, a pair of relatively movable collars mounted upon the shaft in spaced relation having their marginal portions spaced apart to form an annular lateral opening, expansible and contractible supporting channel, said contact members being swingingly supported at one end in said channel and adapted to swing outwardly under centrifugal influence, an annular contact surface engaged thereby, the edge of said channel formed by one of said collars being adapted to stop the inward movement of the contact members and means tending to hold the contact members in engagement with said collar. v

llQIn an apparatus of the character described, a rotatable shaft, contacts arranged about said shaft, a pair of relatively adj ustable collars carried by the shaft having their peripheral margins formed to provide an annular supporting channel of variable width, an annular series of centrifugally actuated oscillatory contact arms pivotally mounted at one end in said supporting channel and adapted to move outwardly into engagement with said contacts, one edge of said annular channel being adapted to stop the inward movement of the Contact arms, and means tending to hold the contact members in engagement with said edge.

12.1In an apparatus of the character described, the combination in a unitary structure of a support adapted to be secured to a shaft including a pair of spaced collars and an inner sleeve supporting both collars, an annular series of Contact members fulcrumed upon one of said collars and eX- tending laterally therefrom into abutting relation with the other collar at one side of the fulcra, the portions of said contact members at the opposite side of the fulcra moving radially by the centrifugal influence into engagement with the surrounding contact surface, a spring yieldingly resisting the radial movement of said Contact members, and an annular contact carried by one of said collars engaged by said pivoted contact members when their radial movement is prevented by said spring.

In testimony whereof, I have hereunto set my hand this 12th day of November, A. D.

EVERETT P. LARSH.

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