US2416973A - Centrifugal switch - Google Patents

Description

Mgrch 4, 1947. G. T. WRIGHT 2,416,973

CENTRIFUGAL SWITCH Filed Dec. 20,. 1944 Invento': f

Georgewrght Pnenied Mu.4,1947

CENTRIFUGAL SWITCH George T. Wright, Fort Wayne, Ind., assignor to General New York Electric Company, a corporation of Application December zo, 1944, serai No. ssaosi (ci. zoo-so) 14 Claims.

My invention relates to centrifugal devices and in particular to centrifugal-switches of the type used for controlling the circuits of starting windings forfvdynamo-electric machines.

An object of my invention is to provide an improved and simplified centrifugal switch.

Another object of my invention is to provide an improved centrifugal switch in which the contacts are arrangedto break the circuit therebetween by a snap-acting switch.

Further objects and advantages of my invention will become apparent and my invention will be better understood from the following description referring to the accompanying drawing. and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part ofthis specification.

In the drawing, Fig. 1 is a side elevational view of a dynamoelectric machine, partly broken away, showing an embodiment of my invention provided therein; Fig. 2 is an enlarged side elevational view, partly broken away, of the switch shown in Fig. l illustrating the position of the elements of the switch in closed circuit position; Fig. 3 is a view similar to Fig. 2 with the, switch elements shown in open circuit position; Fig. 4 is a plan view of the centrifugal operating device for the embodiment of my in- 4vention shown in Figs. 1, 2, and 3; Fig. 5 is ,having a stationary member I and a rotatable member mounted on a shaft 2 supported in the -stationary member. This dynamoelectric machine may be considered as a single phase induction motor with excitation provided by a main' field exciting winding and a starting -iield exciting' winding which is adapted to be deenerwhen the rotatable member of the machine attains a predetermined speed and to be energized when the rotatable member operates .belo w-the predetermined speed or is stationary and power is turned on the machine. In order to disconnect such a starting wind in the electrical circuit of the machine at -th ev;desired "speed, 1 provide a centrifugal switch iwhicnisadapted to -close the electrical circuit of the for' all speeds below a predetermined speed and to open the circuit 2 starting winding through the contacts of the switch above this predetermined speed. This centrifugal switch includes an electrical contact 3 which is resiliently mounted on a flexible leaf spring I and is adapted to make and break an electrical circuit with another electrical contact 5 which is resiliently mounted on another leaf spring element 6. The two resilient mountings for the contacts I and 5 are insulated from each other by an insulating element 'I and are suit- Vably mounted on another insulating element 8 secured to an end .shield 9 of the stationary member I of the machine. The mounting member also includes a relatively rigid retaining plate -I0 which is adapted to provide a stop for limiting the movement of the electrical contact 5 toward the contact 3 by limiting the movement of the leaf spring such that the two contacts 3 and 5 are arranged relatively close to each other and out of engagement in open circuit relationship when the two leaf springs are not deflected, as shown in Fig. 3. The contacts of the spring are adapted to be operated by a centrifugally operable overcenter snap spring device which includes a snap spring formed as two fingers II extending inwardly from a mounting plate portion l2 which is secured at each end thereof between three fingers I3, I4, and Il formed on a supporting clip member I6 which is secured by-a hollow rivet I'I to the rotatable member shaft 2. A pair of weights Il is secured to the snap spring member for operating the spring fingers II across dead center in response to the action of centrifugal force on the weights I8. One of these weights is secured to each of the snap spring fingers II in any suitable manner, as by welding or brazing of an end II! of the weights to the fingers II, and the weight I8 is provided with an angularly extending link portion 20 which extends from the end I! -to the weighted portion of the weight I8 through an opening 2| formed in the mounting clip I6. The switch contacts 3 and 5 are adapted to be operated by a closing member having an engaging element formed as a cap 22 of insulating material mounted on a guide pin 23, which are both secured to a spring clip 2l having spring fingers arranged in operative engagement with the inner ends of the snap spring fingers II and biased outwardly from the rotatable member shaft 2 towards the contacts 3 and '5 by a resilient coil spring 25. This coil spring is arranged in engagement with the engaging member clip 24 and with the inner end of the of a socket 20 formed in the end of the rotatandere able member shaft 2 for biasing the engaging member cap 22 away from the rotatable mem- A berandy towards the spring contacts for closing these contacts against the action of the snap spring fingers ii belowa predetermined speed of the rotatable member. The weight members are formed such that when'the rotatable member attains a predetermined speed the centrifugal force on the weighted portion thereof moves these members outwardly away from the axis of rotation of the rotatable member shaft 2, thereby drawing the snap spring fingers il towards the end of the shaft 2 and away from the switch contacts 3 and 5 against the compressive force of the coil spring 25. The snap spring fingers il and the rigid stop i@ are so positioned as to cause the fingers ii to pass dead center either prior to or lat the time that the rigid -stop member l@ prevents further movement of the contact 5 towards the contact 3, thereby providing for a quick snap and breaking of the electrical contaci-l between the contacts when the spring ngers ii pass over dead center, thus minimizing arcing and burning or pitting lof the switch contacts.

In Fig. 5, I have shown another embodiment of my improved centrifugal operating device for a centrifugal switch in which a pair of spring ngers al! formed as an overcenter spring member are held in place by a spring clip member 28 formed with a pair of fingers 28 on each end thereof which extend over shoulders on the spring fingers 2l. This centrifugal device is adapted to operate a set of contacts 3 and 5 similar -to those shown in the other figures of the drawing by a closing member including an engaging element formed as a cap d@ of insulating material mounted in an opening between the two spring ngers 2 and arranged in operative engagement with a coil spring 3i which is adapted to bias the cap 3@ towards the contacts of the switch and away from a shaft 32 of the rotatable member of. a dynamoelectric machine. In order to maintain these elements of the centrifugal operating device in proper alignment, a pin 33 is securedl in the inner end of the capd and extends into the resilient coil spring 3i into the end of the pocket in the shaft 32. A centrifugal weight 3d is secured to the end oi" each of the snap spring fingers 2l for operating the spring ngers across dead center in response to the action of centrifugal force on the weight. These weights are formed such that when the rotatable member attains a predetermined speed, the centrifugal force thereon moves these weights outwardly away from the axis of rotation of the rota-table member shaft 32, therebyA drawing the snap spring ngers 2l towards the end of the shaft and away from the switch contacts against the compressive force of the coil spring d i. The snap spring ngers 2 are so located as to provide for a quick snap and breaking of electrical contacts when the spring fingers pass over dead center. The coil spring 3i is adapted to bias the operating cap member 30 into closed switch contact position away from the end of the shaft 32 for all speeds of the rotatable member below a predetermined value. This construction operates in the same manner as the switch shown in Figs. 1 to 4, inclusive', and is a simpler device with f ewer moving parts.

In Fig. 6, I have shown another application of my improved switch construction, vin which the switch contacts il and'ii are mounted in an enclosing end shield 35 of a horizontal shaft motor operating device embodying my improved construction. Forl illustrative purposes, the centrin-v ugal device is shown the same `as that of Fig. 5 in which-the Weight elements 3d are secured to the ends` of the spring fingers 2l., In suchan arrangement the weight elements '36 of the centrifugal device dip into oil 3b in the.y lubricant reservoir and during operation throw it outwardly, as shown by the dotted line 3i against the end shieldfrom which it drains back to the reservoir and passes over the contacts i and t, and thereby supply lubricant 'to the contacts during normal operation of the dynamoelectric machine. This lm of oil is wiped from between the contacts when closed and. is drawn toward the center of the contacts by surface tension when the contacts are opened to aid in extinguishing the current therebetween. This has been found to be very eective in operation.

Whilel I have illustrated and described a particularembodiment of my invention, modifica tions thereof will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular arrangement disclosed, and I intend lntheap- 'pended claims to cover all modifications which do not depart from the spirit and scope oi my invention. l

What l claim as new and desire to secure by Letters Patent of the United States is:

l. A centrifugal switch including a pair of electrical contacts, an overcenter snap spring, means including a pair of weights secured to said snap spring on the side thereof away from said contacts in a position for movement outwardly under the influence of centrifugal force and for moving said snap spring in a direction past dead center away from said contacts above a prede` spring to said rotatable member, means including a pairl of weights secured to said snap spring on the side thereof away from. said contacts in a position for movement outwardly from the axis of said rotatable member. under the infiuence of centrifugal force and formovlng said snap spring in a direction past dead centerawayfrom said contacts above a predetermined speed, means for biasing said switch contacts below a, predetermined speed to closed position against the action of said snap spring' and said weights.

3. A centrifugal switch including a `pair of electrical contacts, an overcenter snap spring, means including a pair of weights secured to said snap spring on the side thereof away from said contacts in a position for movement outwardly under the influence of centrifugal force and for moving-said snap spring in a direction past dead center away from said contacts above a predetermined speed, means including a switch contact closing member, and resilient means for biasing said switch closing member towards said switch contacts for closing said contacts below a pres determined speed against the action of said snap g spring and said weights.

4. A centrifugal switch including a pair of electrical contacts, a rotatable member, an overcenter snap spring formed as two fingers, meansk for 'securing said snap spring to said rotatable member, means including a pair of weights rigidly secured one on each of said snap spring fingers in a position and at an angle for movement outwardly from the axis of said rotatable member under the influence of centrifugal force and for biasing said snap spring fingers in a direction past dead center away from said contacts above a predetermined speed, means for biasing said switch contacts to'closed position below a predetermined speed against the action of said snap spring fingers and said weights.

5. A centrifugal switch including an electrical contact, means for mounting said electrical contact, a second electrical contact, means for mounting said second electrical contact adjacent said first-mentioned contact, means forming a stop for retaining said second contact normally out of contact with said first-mentioned contact, a rotatable member, an overcenter snap spring, means for securing said snap spring to said rotatable member, means including a pair of weights secured to said snap spring on the side thereof away from said contacts in`a position for movement outwardly from the axis of said rotatable member under the inuence of centrifugal force and for moving said snap spring in a-direction past dead center away from said contacts above a predetermined speed. means including a switch contact closing member, and resilient means for biasing said switch closing member towards said switch contacts for closing said contacts against the action of said snap spring and said weights below a predetermined speed.

6. A centrifugal switch including an electrical contact means for mounting said electrical contact, a second electrical contact, means for mounting said second electrical contact adjacent said mst-mentioned contact, means forming a stop for retaining said second contact normally out of contact with said first-mentioned contact, a rotatable member, an overcenter snap spring, means for securing said snap spring to said rotatable member, means including a pair of weights rigidly secured to said snap spring on the side thereof away from said contacts in a position for movement outwardly from the axis of said rotatable member under the influence of centrifugal force and for moving said snap spring in a direction past dead center away from said contacts above a predetermined speed, means including a switch contact closing member operatively engaging said snap spring, and resilient means for biasing said switch contact operating member away from said rotatable member and towards said switch contacts for closing4 said contacts against the action of said snap spring and said weights below a predetermined speed.

'1. A centrifugal switch including an electrical contact, means for resiliently mounting said electrical contact, a second electrical contact, means for resiliently mounting said second electrical contact adjacent said rst-mentioned contact, means forming a stop for retaining said second contact normally out of contact with said firstmentioned contact when said resilient mounting means are not deflected, a rotatable member, an overcenter snap spring, means for securing said snap spring to said rotatable member, means including a pair of weights. rigidly secured to said snap spring in a position and at an angle for movement outwardly from the axis of said rotatable member under the influence of centrifugal force and for biasing said snap spring in a direction past dead center away from said contacts, meansl including a switch contact closing member having an engaging element operatively engaged with said snap spring, and resilient means for biasing said engaging element away from said rotatable member and towards said switch contacts for closing said contacts against the action of'said snap spring and said weights below a predetermined speed. v

8. A centrifugal switch including a pair o electrical contacts, with means for retaining said contacts normally out of closed circuit relation, a rotatable member, an overcenter snap spring formed as two fingers, means for securing said snap spring to said rotatable member, means including a pair of weights rigidly secured one on each of said snap spring fingers on the side thereof away from said contacts in a position for movement outwardly from the axis' of said rotatable member under the iniiuence of centrifugal force and for moving said snap spring fingers in a direction past dead center away from said contacts, means including a switch contact closing member operatively engaging said snap spring fingers, and resilient means arranged in engagement with said switch contact closing member and said rotatable member for biasing said switch contact closing member away from said rotatable member and towards said switch contacts for closing said contacts against the action of said snap spring lingers and said weights below a predetermined speed.

9. A centrifugal switch including a pair of electrical contacts, with means for retaining said contacts normally out of closed circuit relation, a rotatable member, an overcentervsnap spring formed as two ngers, means for securing said snap spring to said rotatable member, means including a pair of weights secured one on each of said snap spring ngers in a position for movement outwardly from the axis of said rotatable member under the inuence of centrifugal force and for moving said snap spring fingers in a direction past deadcenter away from said contacts, means including a switch contact closing member having an engaging element of insulating material operatively engaged with the ends of said snap spring lingers, and resilient means' arranged in engagement with said engaging element and said rotatable member for biasing said v engaging element away from said rotatable mem-- ber and towards said switch contacts forclosing said contacts against the action of said snap spring fingers and said weights -below a predetermined speed.

10. A centrifugal switch including a pair of electrical contacts, with means for retaining said contacts normally .out of closed circuit relation, a rotatable member, an overcenter snap spring formed as two lingers, means' for securing said snap spring to said rotatable member, means including a pair of weights rigidly secured one on each of said snap spring fingers in a position and at an angle for movement outwardly from the.

axis of said rotatable member under the influence of centrifugal force and for biasing said snap spring fingers in a direction past dead center away from said contacts, means including a switch contact closing" member having an engaging element of insulating material operatively engaged with the ends of said snap spring fingers, and resilient means including a coil spring arranged in engagement with said engaging ele'- ment and said rotatable member for biasing said engaging element away from said rotatable member and towards said switch contacts for closing said contacts against the action of said snap andere spring iingers and said weights below a prede- Y termlned speed.-

li. A centrifugal switch including a pair of electrical contacts, a rotatable member, an overcenter snap spring formed as two angers, means for securing said snap spring to said rotatable member, lmeans including a pair of weights se cured one on each of said snap spring ngers on the side thereof away from said contacts "n a position for movement outwardly from the axis of said rotatable member under the inuenee of centrifugal force and formoving said snap spring fingers in a direction past dead center away from said contacts above a predetermined speed, means including a switch contact closing member having an engaging element of insulat= ing material operatively engaged with the ends of said snap spring fingers, and resilient means arranged in engagement with said engaging element and said rotatable member .for biasing said engaging element away from said rotatable mexn-` ber and towards said switch contacts for closing said contacts against the action ci said snap spring fingers and said weights below a predetermined. sneed.

12. a centrifugal swam including apen or electrical contacts, a rotatable member, an over= center snap spring formed asl two ngers, means for securing said snap spring to said rotatable member, means including a pair of weights rigid- 1y secured one on each of said snap spring ngers on the side thereof away from said contacts in v a position for movement outwardly from the axis tending inwardly from a. mounting plate, means including a supporting member for securing said snap spring to said rotatable member, means including a pair of weights secured one on each of said snap spring lingers on the side thereof awa'r from said contacts in a position for movenA outwardly from the axis of said rotatable men \er under the iniiuence of centrifugal force and or moving said snap spring fingers in adirection past dead center away from said contacts, means including a switch contact closing member having an engaging element of. insulating material and a guide pin secured thereto with a clip arranged in operative engagement with the ends of said snap spring ngers, and resilient means including a coil spring arranged in engagement with said engaging element and said rotatable member for biasing said engaging element away -from said rotatable member and towards said switch contacts for closing said contacts against the action of said snap spring iingers and said weights below a, predetermined speed.

14. A centrifugal switch for a dynamoelectrlc machine arranged in a lubricant reservoir and including a pair of electrical contacts, means for mounting said electrical contacts normally out of lubricant in said reservoir, a rotatable member, and a centrifugal operating device including an overcenter snap spring, means for securing said snap spring to said rotatable member, means including a pair of weights rigidly secured to said snap spring in a position for movement outwardly from the axis of said rotatable member under the influence of centrifugal force and for moving said snap spring in a direction past dead center away from said contacts above a predetermined speed, said centrifugal operating device being gaging the'ends of said snap spring fingers, and

resilient means arranged in engagement with said engaging element and said rotatable member for biasing said engaging element away from said rotatableA member and towards said switch cons tacts'for closing said contacts against the action of said snap spring fingers and said weights below a' predetermined speed.

13. A centrifugal switch including a pair of y electrical contacts, a rotatable member, an over arranged to extend in said lubricant reservoir into lubricant at normal lubricant level for supplying lubricant from said reservoir to said contacts during normal operation of said machine, means including a switch contact closing member operatively engaging said snap spring, and resilient means for biasing said switch contact closing member towards said switch contacts for closing said contacts against the action of said snap spring iingers and said weights below a predetermined speed.

GEORGE T. WRIGHT.

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