US1713203A - Centrifugal switch - Google Patents

Description

May 14, 1929. I A, F2 WELCH 1,713,203

CENTRIFUGAL SWITCH l l Filed Oct. 5, 1927 Fig/.6 /Saa E l a1. f2 W sul? /0 /wf' W25 l I Ja -f Inventor; fa

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.IE7 bg M f Patented May 14, 1929.

UNITED VSTATES A 1,713,203 PATENT OFFICE.

ALFRED I. WELCH, OF FORT WAYNE, INDIANA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAL SWITCH.

Application led October 5, 1927. Serial No. 224,262.

My invention relates to switches and more particularly to centrifugally actuated switches.

The object of my invention is to provide an improved and simplified centrifugal switch that will open or close thecircuit connected thereto with a snap action when it reaches the speed of rotation for which it is adjusted to operate and that will have -no tendency to return to its initial position until its speed of rotation has substantially decreased. I obtain these operating characteristics by providing rotatable weights acting on a corruaccompanying drawing and the features: of

l Fig. 3.

novelty which characterize my invention will be pointed out with particular-ity in the claims'annexed to and forming a part of this specification. l

l In the draWing','Fig. 1 is allon'gitudinal section of a commutator short circuiting'device embodying my invent-ion; Fig.'2 is an endfelevation of the, device shown in Fig. 1 partlybroken away; Fig. 3 is a View similar to Fig. 1 showing'the commutatorl short circuited; Fig. 4 isan elevation of the corrugated spring member; Fig. 5 is a side elevation of the corrugated spring member shown yin Fig. 4; Fig. 6 is an enlarged fragmentary view of the short-circuiting devicev in the position shown in Fig. 1,' and Fig. 7 is an enlarged fragmentary View -of the short-circuiting device in the position in which the commutator is short circuited, as shown in Referring to the drawing, thecentrifugal switch, Which I havefshown for convenience in illustration, is arranged to short circuit the commutator 10 of av repulsion induction motor. The commutator is secured to a shaft 11 of the motor and includes insulated segments 10a,the ends of which project beyond the hub of the commutator to form contacts 10b 'to engage a suitable short circuiting device. In accordance with my invention the device for short circuiting the commutator l comprises a tplurality of Weights 12 which are supporte adjacent the ends ofthe commutator segments by a plate 13 -having' a flange 13a thereon. The flange 138L engages the edges 12a of the Weights so that the are adapted to be tilted from the position s own in Fig. 1 relative to the plate 13 and brought into engagement with the contacts 10b of the commutator segments, as shown in Fig. 3. The weights are yieldably vretained against the plate 13 and out of engagement with thev commutator segment`s,'as shown in Fig. 1, by a corrugated concave annular spring member 15. The spring member is supported on a collar 14 with its inner periphery abutting rings 15a retained against the flange 143L of the collar 14-and its outer periphery extending into notches 12b formed in the Weights 12 in engagement With a bearing ring 16. The concave fa of the spring member is directed toward the plate 13 so that it can be deflected by the centrifugal force of the weights to decrease the concavity ofthe surface with a snap action. When the concavity of the spring member 15 is decreased by flexing it from the concave configuration shown in Figs. 1 and 6 toward Hthe flattened configuration shown in Figs. 2 and 7 ,the movement takes place with a vsnap action because the initial resistance of the spring member to the force exerted by the weights is a maximum, and decreases as the spring member is flattened. The resistarce oftjhe spring member decreases in this manner, because as the spring member is flattened the deformation and peripheral elongation thereof becomes less in .proportion to the movement of the outer` periphery axially of the shaft. By inserting or removing some of the rings 15a the tension spring member 15 can be varied to change the speed at which the centrifugal device short' circuits the commutator. I have found that by providing the spring member 15 With radial corrugations that its resistance to breaking under continually repeated flexure decreasing its concavity is greatly increased so that it is very seldom-necessary to replace the same. Flexing a concave plate so as to flatten it subjects the outer periphery to tension and elongation which in a fiat plate is resisted by adirect tensional stress in the plate. Radially corrugating such a plate decreases the elongation in the periphery of the plate because the tension is resisted by bending in the corrugatio-ns of the plate which tends to flatten them. For this reason raa short circuitiiig device can be tilted into en-` gagement with the commutator segments tov short. circuit the commutator.

In operation of the motor the commutator and the short circuiting device aie rotated by the shaft 11 and the centrifugal'force'of the weights 12 tilts them about their edges 12a until the weights aie brought into engagement with the contacts 10b of the commutator segments and short circuits the cominutator. This movement of the weights under the action of centrifugal force is resisted bythe concave spring member 15. The resistance of the spring member to the movement of the weights l2 decreases as its concavity decreases so that initially the spring member offers its maximum resist-ance to the movement of the weights.' However, when the centrifugal force of the weights becomes great enough to flex the spring member from the position shown in Figs. 1 and 6 toward the position shown in Figs. 3 and 7 its con-v cavityv will be decreased until it is substaiitiallyflat and consequently its resistance to the centrifugal force of thevweights will be decreased also, so that when the shortcircuitin@ device reaches a speed such that the weights 12 will flex the spring member 15 it will move with a snap action into the position shown in Fig. 3 with the weights 12 in.

engagement with the contacts 10b of the cominutator segments and short circuit the cominutator. Moreover, as the resistance of the spring member 15 has been substantially decreased by flexing it to the position shown in Fig. 3 there will be no tendency for the weights 12 to return to their initial position until there has been a substantial decrease in the speed of rotation of the short circuiting device.

Although' in the present instance my invention is embodied in a centrifugal short l circuiting device for a commutator, 1t is ap' parent that it is applicable as well to a eentrifugal switch of any other form. I desire to be understood, therefore, that my invention is not limited to the particular embodiment shown and described and I intend in the appended claims to cover all modifications whiclido not depart from the spirit and scope ofiny invention.

That I claim as new and desire to secure by Letters Patent of the United States, \is,-'

1. A centrifugal switch comprising a rotatable element and contacts, a corrugated vspring member having a concave surface so that it is adapted to be flexed with a snap action to decrease the concavity of said surface, and means actuated by centrifugal force produced by rotation of said element for annular spring member having a concave surl face so that it is adapted to be flexed-with a sna action to decrease the concavity of said sur ace and means actuated by centrifugal force produced by rotation of said element for flexing said spring member and controlling the circuit between said contacts. v

3'. A centrifugal switch comprising a rotatablel element and contacts, an annular spring member having radially extending corrugations and a concave surface so that it is adapted to be flexed with a snap action to decrease the concavity of'said surface, and means actuated by centrifugal force produced by rotation of said element for flexing said springmember and controlling the circuit between said contacts.

4. A centrifugal switch comprising a rotatable element' and contacts, a corrugated annular spring member having a concave surface so that it is adapted to be flexed with av snap action to decrease the concavity of said i surface, means for supporting said annular member including a rotatable element engaging its inner periphery, and means actuated by centrifugal force produced by rotation of. said element for flexing said annular member about its support and controlling the circuit between said contacts.

5. A centrifugal switch comprising a rotatable element and contacts, a corrugated annular spring member having a concave surface so thatitis adapted to be flexed with a snap action to decrease the concavity of said surface, means for securing said annular member to said rotatable element, and means actuated by centrifugal force'l produced by rotation of said element forilexing said annular member about its support and controlling the circuit between said contacts including Weights arranged about the periphery of said member. V

6. A centrifugal switch comprising a rotatable element and contacts, an annular spring member liavinga concave surface so that it is adapted to be flexed with a snap action to decreasevtlie concavity of said surface, means for supporting the inner peripheryof said annular member, a plurality of weights arranged about t-lie periphery o said annular member in engagement therewith, and means for controlling the circuit between said contacts including means for movably supporting said vweights so that upon rotation of said element the vcentrifugal force of said Weights will iex said annular --member with a snap action and `control the circuit between said contacts..

7. In combination with a commutator, an annular spring member having a, concave surface so that it is adapted to be`flexed with a snap action to decrease the concavity-of said surface, a plurality of weights arranged about the periphery of said4 annular member in engagement therewith and spaced from the segments of said commutator, and means for movably supporting said Weights'so that upon rotation of said element the centrif ugal force of said weights will ex said annular member With a snap action and bring saidV Weights into engagement with the segments of said commutator for short circuiting the same. n

In Witness whereof, I have hereunto set my hand this 1st day of October, 1927.

f ALFRED F. WELCH.

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