US2657920A - Centrifugal device - Google Patents

Description

Nov. 3, 1953 yW; D, HARRISON k2,657,920

CENTRIFUGAL DEVICE F11/ed oct. 3o, l195o Patented Nov. 3, 1953 UNITED STATES ATENT OFFICE CENTRIFUGAL DEVICE Walter D. Harrison, Rochester, N. Y., assigner to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Claims. 1

This invention relates to centrifugal mechanism and more particularly to such mechanism of the type used for operating switches adapted to control the starting windings of dynamoelectric machines.

The use of centrifugal mechanism mounted on the shaft of a dynamoelectric machine to operate a switch for disconnecting the starting windings after the machine has come up to a certain speed, is well known. In order that there will be no sparking at the contacts, it is necessary that the contacts be separated with a snap action. In order to get this snap action, prior mechanisms have been rather complicated in construction and required a number of complicated parts.

An object of the present invention is to provide an improved centrifugal mechanism for operating a switch with a snap action.

Another object of the present invention is to provide an improved switch operating centrifugal mechanism for use on a rotatable shaft.

The above and other objects of the present invention are accomplished by providing a support or plate xed to the shaft and having a weighted member pivoted to the plate and a sleeve located on the shaft and adapted for sliding axial movement on the shaft. A coiled spring is located around the pivot of the weight and has one portion engaging the weighted member and another portion engaging the plate. The sleeve which is adapted to operate the switch is moved by a U-shaped lever made of music wire. This lever is pivoted on the pivot of the weighted member and has portion embracing lugs on the sleeve. A pair of springs are connected to the Weighted members and to the yoke and are normal beyond the dead center of the pivot member for the weights. These Weights are adapted for pivotal movement under the action of centrifugal force in response to the rotation of the shaft and move the spring to the other side of dead center against the force of the first mentioned spring and causes the lever to shift the sleeve to another position and operate the switch at a predetermined speed of dynamoelectric machine and showing in detail.

the centrifugal mechanism in its normal state.

Fig. 2 is a view similar to Fig. l but showing the centrifugal mechanism in its operative postion.

Fig. 3 is a top plan view of the mechanism looking in the direction of arrow 3 of Fig. 1.

Fig. 4 is a sectional view taken on line 4 4 of. Fig. 3.

Fig. 5 is an end View of the mechanism taken on line 5 5 of Fig. 1.

Figs. 6, 7, and 8 are top, end, and side views,

respectively of the shifting lever used in the present invention.

Fig. 9 is a fragmentary sectional view illustrating the formation of a stop on the plate it.

Referring to the drawing there is shown a fragment of an end member 2 of a dynamos electric machine. A rotor 2| of any standard construction is mounted on a shaft 22 which is rotatably mounted in a bearing surface 23 provided by the end member, only a fragment of the rotor is shown. The machine is provided with a single-phase main field winding a starting eld Winding, not shown. These windings are mounted in the conventional manner.

It is well known in the art that in a single phase induction motor having separate starting and running windings, it is desirable that the starting eld exciting windings should be energized during the period when the motor starts from a standstill, or under operating conditions that the speed of the motor is reduced below a predetermined value. It is also desirable that the starting field exciting windings should be deenergized when the speed of the motor exceeds a predetermined value. In order to accomplish this result, there is provided a switch 25 mounted on a switch support 2t made of insulating material which is secured to the end member 2%). The switch is provided with electrical contacts 21 and 28 which are connected to the energizing circuit of the starting field exciting Winding.

Referring to Figs. 1 and 2, the stationary contact 2l is adapted to-be connected to the stator winding of the motor, not shown. This stationary contact 21 is normally engaged by the movable contact 28 carried by an arm 2Q, which is pivotally secured to a stud screw (it attached in the end frame 2li of the motor. A spring 3|, disposed between the arm 29 and the frame 20, yieldably urges the arm 29 so that its contact 28 is moved out of engagement with the stationary contact 21. The arm 29 is proon to form a central tubular portion or flange.

4l which may be connected to the shaft in any suitable manner, preferably by a press fit' soV that the plate is rotatable therewith. As viewed in Fig. 3 the upper side of the plate'has two.-

apertured ears 42 on opposite sides thereof to receive a cross pin 43 having annular grooves adjacent its ends. A U-shaped cradle 44" pivots' on the pin 43 with its side arms 45 positioned outside of the ears 42 of the plate. The ends of the sideb arms are'providedwith a notch to provide flat surfaces 46-andf41 which cooperate with-'aston 48 on the plate to -lirnit the pivotal movement-of the cradle. `441.- The formation of.

the stop 48 on plate 40 is clearly illustrated in Eig. 9. A1 centrifugal weight 43- is attached to the yoke ofA thelcradle: 44. A- spring 56 havingv two coiled portions eneircles the pin 43-with the ends 52 lying against the top of the plate 404 and with.` acentral bowed portion 53` engaging the weight 49 to urge same and the cradle inwardly untill the` surface 41- contacts with the stop 43 as clearly shown in Figs. l and 4. The outward movement of the cradle and weight takesplaceagainst the tension of the springv U.

Thesleeve 331s. slidable on the shaft 2-2 between the platesw and a-Cewasher 55 tted in a groove on the shaft 22. This sleeve is formed witlil integral diametricallyv opposed.- lugs 56 whichare-embraced by a portion of a U-shaped lever 66 so that upon.V pivotalmovement ofthe weight cradle` 44 about-the pinr 43` as the axis.- the sleeveV 33v will be moved axially' along the shaft122. The lever 6.0/as shownin its-preferred formisimade from, av single-length of music wire of suitable' stillness-and of uniform diameter and isso. formed-as tolprovide bowed or arched portion-6I andfromthe opposite ends ofthe arched portion (il horizontal, loops 62 are formed in the saine plane: as thearched portion. These loops extend downwardly from the archedl portion. The lower' ends ofthe loop portions continue and are=bent soas-to. provide parallel arms 63. The arms 631 are formedwith an actuating'loop elee mentz64: These, loop elements 64 are so placed that they.- will embrace the lugs 56 as shown in lli'gs;V iV and 2- The free ends of the arms.r 63 are: formed with hooks 65. These hooks are open and' of: suchy size andshapethat theywill snap. into. the annular grooves: formed adjacent the. endsy of the: pin 43 and will hold the pin in resembled relation with the plate-40. When the hooked'- ends 65 'of the lever' 63 are attached-to the pin 43, the loop portions- 64 will embrace theflugs 56 and the arched portion will bey extended above the collar 4l. Thel cradle 44. is provided with ears 66.struck' out from each arm. A hole isy provided-in each ear into which an. end of' a spring 61 may be hooked. The other end of the spring; 61 s-hooked through the. loop 62 in the-lever. 60. The springs. 61V whenv in their normal position exert a force which causes the side 64a of. the-loop64- to bear against the lug.A 46 to urge the sleeve 33 to the right. toclose the contacts 21 and 28 and the spring 61 will be below the axis of pin 43.

In operation of the mechanism the switch as'- shown in Fig. 1 is in a closed position, corre-v sponding to the position when the rotor is idleor running at slow speeds. In this position thecontact 28 engages contact 21 and the actuating' member or sleeve 33 is exerting a pressure onty the rubbing blocks 32 ofarml due to the effect-- of. springs 611. When the main circuit` throughthe motor is closed the rotor will start to rotate.- As the rotor 2l increases in speed consequently' the centrifugal force acting on cradles 44 'isi increased: This results in tensioning the springsy 5I and: 61 and. causes the ends of the spring' 61,. which'are: hooked over the ears 66, to move' outwardlyY with they cradle 44. This results in expanding the springs 61. As the motor increases its speed the springs 61 will move over' dead-center position of pin 43. When that hap4 pens the springs 61 will return toward theirl normal state thereby.- causing the. spring ends: hooked in the eyes .62jof'1ever 6U'to lift the yoke: 6L ina. clockwise direction, from the position shownin Fig. 1 to that shown in Fig. 2". This1 causes the springs to snap over center position.. Consequently the loop 64 moves to theleft causing the surface 64b of' loops 64'to. engage the-lugs'V 56. to move. the sleeve 33 to the left. that` happens the contacts 21.,` 28 will separate due to` action ofspring 3l'. which urged the; arm 29 to the left, and.' the starting field; exciting, winding` willi be disconnected; When the centrifugal'movement.v has gone far enough the'sur faces 46` will contact the stop 48. stopping thek rotational movement offthe cradle 44].' in av coun-- terclockwise direction.

As the motor speed is reduced toY a` predeter` mined. degree. the spring 56 will overcome'` the eil'ects of centrifugal` force andA movefthe` cradle 44 clockwisefabout; the pin- '43' and as the.'y same approaches its normal position the springs'y 61 will snap. pastdeadcenter position andthe sur face. 41A will engage stop. 43,4 stopping the rotationalmovement ofthe cradle 44' in a clockwise direction` asviewed'in. Fig. 2'.. When the spring snapspast dead center the surface 64aV of loop 64 willbear. against. the lug 46 to urge' the. sleeve to` the right.' to. close the contacts 21 and' 28. Since. the lever 6.6 is. formed' from musiciwlrej'it will. be apparent thatv less friction between the parts is. had.. andlthatl a greatly simplified* centrifugal. mechanism having toggle snap action features with the. minimum number of parts is `providecLtl'iat is, the4 supporting, plate .40; cradle '44, weight 49. pin, 43 spring 5|).` two springs 61, lever 60' and sleeve 33; This centrifugal mechanism not only permits ease in` assembly, but also provides for the control of inward andoutwardV movements o1"v the weights.

The lower portion' of the'platelasviewed in Figs. l; 2y andf has angular portions 1-6-to provide vanes'which set air in motion for the purposev of cooling the motor.

While the emb'o aliment ci' the `presentinvention as herein disclosed; consti-tutes a. preferred-form; it. is torbe understood that otherfformsimight be a'doptedl.

What is claimed is as follows:

1:. A. centrifugal mechanism for. controlling a switch connprisingA a rotatable shaft;-` a plate hav.- ingits centra-liPort-ionfxed to. the shaft; a. sleeve adapted for sliding axialmovement. on the-shaft for. operating the. switch.; extensions associated with the sleeve; a cross-pin carriedy by the plate; a weighted member pivoted on the cross-pinand adapted for pivotal'movementunder centrifugal force; a l'J-'sluiped4 lever-having ayoke and a. pair of arms formed froma single length of 'stiff wire having its arms pivoted on the cross pin, said arms having loop portions engaging the extensions on the sleeve for actuating same; and spring means connected with the weighted member and the yoke of the lever adapted to move to either side of the axis of said cross-pin for causing snap action of said sleeve; and single stop means formed integral with the plate for limiting the movements of the weights in either direction of its travel.

2. A centrifugal mechanism for controlling a switch and adapted for use on one end of a rotatable shaft, said mechanism comprising; a support form of relatively thin-metal having its central portion secured to the shaft; a sleeve having diametrical lugs on its outer surface adapted for sliding axial movement on the shaft; a cross member carried by the support on one side of the shaft; a weighted member pivoted on the cross member, said weighted member being adapted for pivotal movement under action of centrifugal force; a U-shaped lever having a yoke and a pair of arms formed from a single length of relatively stiff wire located on said mentioned side, each arm having a loop portion embracing a respective lug of the sleeve and having a hooked end pivoted to the cross member; and spring means located on opposite sides of the support and having one end connected with the weight member and having the other end connected with the yoke of the lever, said spring means being adapted to move to either side of the cross member for causing snap action to said lever and sleeve.

3. A centrifugal mechanism for operating a switch, and adapted for use on a rotatable shaft, said mechanism comprising a plate of sheet metal having its central portion secured to the shaft; a sleeve of insulating material mounted on the shaft and adapted for sliding axial movement thereon for actuating the switch, said sleeve having a pair of diametrical lugs on its outer surface; a weighted member pivotally mounted on the plate on one side of the plate; spring means opposing the action of centrifugal force upon the weighted member; a U-shaped member having a yoke formed of music wire for shifting the sleeve, said member having a pair of loop portions, one of said loop portions being adjacent the extremities thereof pivoted on the pivot of the weight and having the other loop portion about the lugs; and spring means movable to and fro across the dead center of the pivot for the weight said spring having one end connected to the weighted member and having the other end connected with the yoke of the U-shaped member and operable to move the lever about its pivot so as to move the sleeve from the movable contact with the outward swing of the weighted member; stop means on the plate for limiting the swing movements of the weighted member in either direction.

4. A centrifugal mechanism for operating a switch and adapted for use with a rotatable shaft, said mechanism comprising a plate of sheet metal having its central portion fixed to the shaft; a sleeve of insulating material adapted for axial movement on the shaft, said sleeve having a pair of integral diametrical lugs on its outer surface; a weighted member pivotally mounted ontheplate and on one side of the shaft; spring means opposing the action of centrifugal force upon the weighted member; a U-shaped lever having a yoke and a pair of armsV for shifting 'the sleeve, said arms being formed withv` loops ir'itermediate its end for embracing the lugs, and with eyes at their ends for pivotal connection with the pivot of the weighted member, said yoke being formed with eye offset portions beyond the normal plane of the arms; a pair of springs, each spring having one end connected with the weight member and having its other end connected with an eye offset portion and located below the dead center of the pivot of the weight member, said springs operating to shift the lever with a snap action when same are moved past dead center for the weights when the weights are under the action of centrifugal force.

5. A centrifugal mechanism for controlling a switch and adapted for use on one end of a rotatable shaft, said mechanism comprising; a support formed of relatively thin sheet metal having its central portion secured to the shaft; a sleeve of insulating material adapted for sliding axial movement on the shaft for operating the switch, a cross pin supported by the plate on one side of the shaft; a cradle weight member having its arms pivoted on said pin, said weight member being adapted for pivotal movement under the action of centrifugal force; a U-shaped lever having a yoke and a pair of arms formed of a single length of music wire straddling the support and cradle and having its arms pivoted on the cross pin, portions of said arms being adapted to engage portions of said sleeve; for actuating the sleeve and spring means connected with cradle and the yoke adapted to move to either side of the dead-center of the cross pin for causing snap motion to said sleeve.

6. A centrifugal device comprising; a plate adapted to -be rigidly secured to a shaft; a sleeve having lateral extensions thereon and movable between positions relative to the plate on the shaft; a stop means associated with the plate; a weight member pivotally supported on the plate and presenting a pair of spaced stop surfaces disposed on opposite side of the stop for limiting angular movement of the weight relative to its pivot; a lever having connected arms disposed on opposite sides of the sleeve, said arms having one end pivoted on the pivot of the weight member and having an intermediate portion operatively connected with the extensions for actuating the sleeve; spring means connected with the weight and the lever for normally urging one of the stop surfaces against the stop and simultaneously causing the lever to move the sleeve to one of its positions while the other stop surface is adapted to contact the said stop for limiting the out movement of the weight when under the influence of centrifugal force; and contact means controlled by the sleeve.

'7. A centrifugal mechanism for controlling a switch comprising; a plate adapted to be attached to a shaft; a sleeve having diametrical external lugs adapted for sliding movement on the shaft; a weighted member pivoted on said plate, said member being adapted for angular movement under action of centrifugal force; a U-shaped lever, each arm pivoted on the plate and having a portion for receiving a respective lug; spring means connected with the weight member and the lever, said spring being adapted to move to either side of the pivot for the lever for causing snap action of the lever and sleeve.

8. In a centrifugal switch, a lever member formed of a single length of music wire and with: eyesfat: timmy#Y inem: cada.: ffm Diwali nection witheaipiuot/mthlmem 9# In; aA centritmalf dwi; w. mammals/ing; au'

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