US1162518A - Centrifugal switch. - Google Patents

Description

H. M. scNElE.

CENTRIFUGAL SWITCH.

APPLICATION FILED JUNE 1T. |910.

1,162,518, Patented Nov. 30, 1915.

-2 SHEETS-SHEET l.

jATTORNEY H. M. SCHEIBE.

cENTmFuGALswITcH.

APPLICATION FILED JUNE I7 |910. 1,162,518, Patented Nov. 30, 1915.

2 SHEETS-SHEET 2.

ATTORNEY nmrnn srnrns remm- J HAROLD yM.' SCHEIBE, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- vHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CRPORATIN 0F Pff.l'NSYlt-v VANI.

cnurnir'uenr. swr'rcn.

specification of Letters Patent. vyat-tentati Nov, 3Q, 1915,

Application filed .Tune 17, 191B. Serial No. 'fl.

- of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Centrifugal ISwitches, of which the following is a specification.

My invention relates to centrifugal switches such as are commonly employed in electrical devices in which circuit connections are made and interrupted at predeter-y mined speeds and it has special reference to fan motors of the single phase alternating current induction type and to starting means therefor.

TheV obj ect of my invention is to provide a switching device of the above indicated character which shall bc'simple and durable in construction, effective in operation and especially adapted for comparatively slow speed devices in which a heavy and positive contact pressure is essential.

It has been common practice, in .single phase alternating current fan motor con- .fstructiom to provide the motor with an auX- iliary winding, of the short circuited shaded coil type, to assist in starting. However, in slow speed motors of this class, such as are frequently employed for ceiling fans, it has been customary to allow the auxiliary winding to be permanently connected in circuit, as no suitable switching device has vbeen known which would operate satisfactorily at slow speeds. It is evident that unnecessary and undesirable power losses have thereforebeen sustained throughout the operation` of Amotors of the kind just mentioned.

My invention embodies means whereby such an auxiliary winding may be shortcircuited upon itself while starting and automatically open circuited when a predetermined running speed is attained, as will be hereinafter described. l

According to my invention, the rotor spider of a fan motor is provided with a pivotally supported canimember, or finger,

which is placed inI its operating position bv centrifugal force. Thev cam member is adapted to operate an unstable spring knuckle switch which is positively opened and closed by a spring when it is engaged by the cam member.A after which no further contact between the members koccurs.` It

which embodies my invention. Fig. 2 is abottom plan view of the rotor spider and associated cam member shown in F ig. l, only a portion of the secondary winding and core being,r shown'. Fig, 3 is a perspective view of the switching device, in which portions of the device are broken away, in order to lshow the various parts with clearness, and Fig. 4: is a diagrammatic view of the circuit connections of the motor.

Referring 'to the accompanying drawings in detail, a fan motor l comprises a stationary laminated primary member 2, that is rigidly secured toa suspension rod orshaft 3 and is provided with a main winding 4 and an auxiliary winding 5, and a rotatable secondary member G which is provided with a winding 7 of the squirrel cage type and with a plurality of fan bladesS. The secondary membery 6 is adapted to rotate about the shaft 3 upon a ball-bearino 9.

During normal operation, the main windingT -i is connected to a Suitable. source of energy (not shown), and, during starting, the auxiliary winding 5 is short-circuited upon itself through a centrifugally operated switching device 10. lVhen such predetermined speed is attained that the auxiliary winding 5 is no longer needed, said winding is automatically open-circuited, as herein` after described.

The centri'tugally operated switching device 10, just referred to, comprises a cum member, or finger 11, which is pivotally mounted on the rotor spider 6, and a switch'- ing device l2, which is; suitably secured to the stationary primary member 2.

The cam member 1l is curved in form and is pivotally secured at 'one end 'to the rotor spider by a screw 13. The'free end 14 of the cam member 1l is of wedge-shape and is adapted to operate the switching device 1Q, as hereinafter described. A supporting vso member 15, which is secured to the rotor spidei 6, is disposed substantially at right 'angles to the mid-position of the cam member 11 and Supportsthe weight of said cam member 18 which ismounted upon a knife blade 19 and is providedwith a coil spring 20 which is adapted'to maintain ysaid switch memberin eitherv its open or its closed position, a' U-shaped' supporting 'member 21, 'a

l stationary contact'terniinal 22 to 'coperate with said switch member 18, and an insulating 'stop 23, to restrict movement in a counter clockwise direction.; The 'switch mem- Vber 18 maybe'made' of sheet metal, which 31 which are, provided in the. side walls32V and 38, respectively', of the `U-shaped supporting membery21."l The spring '20 is fastenedv to the bottom 3 4 'of said U-sh aped member 21 and is vhooked over the knife blade v19 andl maintained under tension.

It is evident` that'the spring knuckle toggle is in unstable 'equilibriumwhen in its dead center position, and that itis only necessary to cause the switch member 18 to be moved'slightly'tothe one side v"or'the other of the deadcenter in order that "the spring 20 shall positively actuate's'aid switch member to either its lfull open or its' full closed position. i' 1" According to my invention, I cause kthe cam member 11 to throw the'swi'tch 18 across its central position at predetermined speeds and I make the l free end 14:l` offsaid cam member of proper shape tol force the toggle past' its dead center position when said'end engages'eithero'f the projections 28 and 2 9. Assuming the various vparts to bein' positions lshown 'inv the drawing's'fand' that the motor is to be started fromI rest with both the main and the Vauxiliary""winding inservice. the operation isA asfollows" As' the motor speds'up, the v centrifuga'l force,` acting upon the' cam member ,11, gradually increasesvuntilY `itis vsufficient to overcome the ytension ofi spring'l, whereupon the cam, member is ,thrown 'out tothe poSi-.

spring 20 then positively carries said switch to its full open position, and thus open-circuits the starting winding 5. I

Vhen the supply of power to the motor is discontinued, the centrifugal force which acts upon the cam member 11 gradually diminishes as the speed decreases, until the tension -of spring 16 overcomes said force, and restores the cam member to its original position.' In this position, engagement with' the projection 29 of the switch member 18 takes place and said switch member is thrown to its closed position against the stationary conta'ct'terminal 22. The auxiliary starting windingis thus short-circuited and the motor is againl in condition for starting. It will be noted that after the Acam member 11 comes into engagement with the switch member '18,the latter is immediately operated to either'its full opener its full closed posi- Ftion and no further contact between said members occurs.

It will, of course, be understood that while I I have shown and described a centrifugal switching device of specific construction, as applied to a fan motor of a particular type and winding, other commercial devices may be readily and advantageously equipped with saidswitching device'for various purposes, and modification in size, arrangement and structure of parts, may be effected without departing from the spirit and scope of my invention.

' I claim as my invention:

1. A switching `device comprising relatively 'stationary and rotatable members, a cam member pivotally mounted on said rotatable member and adapted toy be moved to one of vits operative positions by.cen trifugal force., a spring opposing such action, a y switch member having knife edge bearings and a spring adapted to actuate said switch memberon eitherv side of its dead center position, said switch member being mounted upon'the stationary member and adapted to be engaged by said cam member at predetermined speeds of revolution and to "be forced thereby to either side of its'dead centerposition, the operating effortl being suppliedby the momentum of the rotatable member.'

.2.1 The combination with relatively sta' I Vside of its dead center position, and a pivotally' supported centrifugally operated cam membersecured tothe zmovable member and adapted.'toactuatesaid switching device to `one side or the other'of'its dead center position, in afplane'fthat is'transverse to the pla'neof action of centrifugal force on said cam member, in accordance with predetermined 4speed conditions.

3; A switching device comprising relatively stationary and rotatable members, a switch member mounted on the stationary member which comprises a stationary Contact terminal, a movable coperating Contact member provided with two projecting cam-engaging members, a knife blade upon which said contact member is supported, a suitable bearing member for said knife blade, a Coil'spring hooked over said knife blade and secured to said bearingr member, and a cam member or `finger pivotally mounted on the rotatable member, and adapted to be placed bv centrifugal force in position to engage the one or the other of said cam-engaging projections under predetermined speed conditions.

In testimony whereof, I have hereunto subscribed my name this 10th day of June, 1910.

iii-mom)v M. scimmia.4

Witnesses:

JOHN A. WoLFE, B. B. HINES.

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