US2048494A - Centrifugal switch - Google Patents

Description

July 21, 1936. F. DIEHL 2,048,494

CNTRI FUGAL SWITCH gmc/Mofo if July 21, 1936i F. DIEHL,

GENTRIFUGAL SWITCH Filed April 4, 1%5 2 Sheets-Sheet 2 u and to close the starting winding o ytainedl thereby will-be Puentes-July 21, 1936 Frederick pieni, Elizabeth, N. J.,

assignorto The Singer Manufacturing Company, fElizabeth,

N. J., a corporation of New Jersey Application April 4, 1935, Serial No. 14,595

4 Claims. (Cl. l21m-80) l This invention relates to centrifugal switch'es, more particularly of the type commonly used in split phase induction motors to open the starting `winding as the motor approaches when the motor speed drops below a predetermined low limit.' A motor of this type is constructed'with a` running winding of relatively heavy wire and a starting running speed winding of relatively finev wiredisposed at an electrical angle to the main winding to produce the necessary starting torque. The main winding is designed to carry the current required for continuous operation of the motor under load but the starting winding which comprises relatively few heavy starting Y'current for a short time only. Hence if `it is not promptlyV opened or disconnected after having served its starting purpose, it may burn out.

The present invention has for an object to provide a centrifugal switch or so-called "cut-out which has asnap-action and'quickly and widely opens the switch contacts in the starting winding circuit ata predetermined motor speed, the def vice also functioning reversely to as quickly close starting winding contacts. Another object of the invention is to provide a centrifugal cuttums is designed to safely carry acomparatively out which functions in such a way as toeliminate all possibility of fluttering and burning of the electrical contacts heretofore causedl by indecisive action of the switch mechanism at certain c/ritical speeds under heavy load.

With the above and other objects in view, as will hereinafter appear, theinventioncomprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated vin the w accompanying -drawings of a preferred'embodl-V ment of the invention, from-which the several features of the invention andthe advantages at skilledintheart.l

In the accompanying drawings` Fig. 1' isl a frag: I

mentary sectional view of a split phase induction readily understood` by thoseV motor embodying the invention;I the switch con-'- ing the contacts open. Fig. 3 is a top view of the parts as'shown lin Fig. 1.a Fig. 4 is a perspective view of an element of the switch voperating mechi anism. Ii'ig. 5 is asection on the line 5 5, Fig. 1.

4g tacts being closed. Fig. 2 is a similar view' show-V w Figs. 64nd 7 are disassembled perspective viewsand jecting lugs 6 of the endspeed-responsive toggle-operating member u Vthe usual squirrel-cage rotor I is carried by the motor shaft I journaled in the motorend-bonnets -one of which is shown at Stationarily mounted on the inwardly probonnet 5 is the insulating supporting base l`I upon which is .fastened by the screw 8 a terminal plate carrying the staytionary contact Iii. 'Ihe movablecontact I-i is mounted on one end of the leaf-spring 'I2 hinged at I3 to the support 1 and having connected to lo it at I4 one of the terminal conductors I5 in the starting circuit/the terminal plate 9 also being connected in the starting circuit by the conductor I6. The leaf-spring member i2 has a ringl Y shaped intermediate portion Il, Fig. 8, which 15 surrounds thev motor shaft I with plenty of clearance space between the two and is formed with a diametrically disposed Vhu'rnp I8 which is pressed upon at times by the insulating washer I9 carried by the sleeve I9 to close the switch; the sleeve I 9 being slidably mounted on the motor shaft. The opening or recovery movement of the :spring member .il may be assisted by the Asmall ance slots!! in the spring member I2.

Sliding movements endwise of the motor shaft 'are imparted to the sleeve Il vto control the 0 'opening' and closing movements of the switch- 3 member I 2 by a centrifugally actuated 4springtoggle mechanism carried by the rotor I. Mounted bn the rotor lbyscrews 23 and spacing nuts 24 is the sheet-metal supporting, plate 2l having 35 the spacedparallel ears n which are Aform withpivot-slots 21 in which `hang the inwardly e 'directed pivotaly extensions 2l oi' the upper arms l'ff H-shaped'toggle-operated lever Il, the

low'er arms of which are bent to form rounded knobs Il which engage the side walls of the vgroove Il in 'the sleeve II.

Pivotally mounted onf-the pin 32 carried by the ears' 2l are the spaced ears 33 of the sheet-metal weight of which is disposed mainly to one side of .45 the pivot-point 32 so that the member M will be caused to turn from the position shown in Fig. 1 to the position shown in Fig. 2 under centrifugal force. The member; 34 may be additionally weighted, if desired, by the attachment thereto of a-plate 35.

Projecting from the 'speed-responsive member Y 34 between the ears u is a toggle-arm 36 carrying a cross-pin 3,1 whlchfworks in the slots Il of the toggle-thrust element 39 having further slots 40 disposed at 90 to the slots 3l and in which the end of the toggle-arm 36 carrying the cross-pin 31 is received. A coiled expansion spring 4I surrounds the toggle-element 39 between the head 42 thereof and the cross-pin 31. This spring retains the groove 43, Fig. 4, in the end face of the head 42 seated upon the crossbar 44 of the H-shaped toggle-operated member 29. A pair of recovery springs 45 are connected between-the ears 46 of the speed-responsive member 34 and the ears 41 of the weights 48 mounted on the plate 25 to balance the weight of thetoggie-mechanism.

When the-motor is at rest, the cross-pin 31 isat one side of a line connecting the pivot-pin 32 and cross-bar 44. Hence the spring 4I urges the toggle-member 39 in a direction to swing the H- shaped lever to the right and force the sleeve I9 in a direction to hold the contacts IB, Il, closed. When the motor is started and attainsa certain speed the speed-responsive member 34 begins to swing outwardly about its pivot 32 and the togglearms 36, 39 approach alinement. When the pin 31 crosses the position of alinement the action of the toggle upon the H-shaped lever 29 is'suddenly reversed and the latter is snapped to the position shown in Fig. 2 and the movable contact li is suddenly and widely separated from the stationary contact I0, with no possibility of fluttering of the contacts or indecisveness in the action of the vparts. By virtue of the present mechanism the contacts must either be well closed or fully opened and cannot occupy any intermediate position except transitorily.

Having thus set forth the nature of the invention, what claim herein istl. A centrifugal switch having a rotary shaft, a support fixed to said shaft, a sleeve slidable on said shaft, a lever pivotally connected to said support and operatively engaging said sleeve, a speedresponsive member pivotally mounted on said support and having a toggle-arm, a springinuenced toggle-arm pivotally engaging said lever and said first mentioned toggle-arm, and a movable electricalcontact arranged to be operated by said sleeve.

2. A centrifugal switch comprising a stationary supporting frame, iixed and movable contacts carried by said frame, a rotary shaft iournaled in said frame, a sleeve movable endwise of said shaft to operate said movable contact, and a speed-responsive spring-toggle shaft for moving said sleeve, said mechanism including pivotally connected toggle elements movable to-and-fro across an intermediate dead-center position, one of said elements being weighted and spring balanced so as to be speed-responsive and the other of said elements being connected to move said sleeve.

3. A centrifugal switch comprising a stationary supporting frame, iixed and movable contacts carried by said rame, a rotary shaft journaled in said frame, a sleeve movable endwise of said shaft to operate said movable contact, and a speed-responsive spring-toggle mechanism carried by said shaft for moving said sleeve, said mechanism including a pivotally mounted weighted toggle-arm, a second toggle-arm having a sliding pivotal engagement with said rst mentioned arm, an expansion spring reacting at its opposite ends against the respective toggle-arms, and a pivotally mounted arm acted upon by said second toggie-arm for moving said sleeve.

4. A centrifugal switch comprising a rotary shaft, a supporting plate carried by and normal to the axis oi said shaft, said plate having a pair of parallel ears normal to the plane of said plate, a. sleeve slidable on said shaft, an H-shaped lever having two of its arms pivotally connected to said ears and its remaining two arms straddling and operatively engaging said sleeve, a speed-responsive member pivotally carried by said ears and having a toggle-arm, a toggle-arm connection between said rst mentioned toggle-arm and the cross-bar of said H-shaped lever, and a movable electrical contact member controlled by said sleeve.

FREDERICK DIEHL.

mechanism carried by saidv

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