US992870A - Centrifugal switch. - Google Patents

Description

G. B. HANRIGHT.

GBNTRIPUGAL SWITCH.

APPLICATION FILLED JUNE 14, 1909.

992,870, Patented May 23, 1911.

M 56 14 l l M ,i' I; v 4/ Q0 4- o \52/ M 1 5 M 5 12/ 45 /8 A6 & I jevenlor UNITED STATES PATENT OFFICE.

CLA ENGE B. HANRIGHT, 0F CAMBRIDGE, MASSACHUSETTS, ASSIGNOR, TU TI IE TZER-GABOT ELECTRIC COMPANY, OF BROOKLINE, MASSACHUSETTS, A COR- PORATION OF MASSACHUSETTS.

CENTRIFUGAL SWITCH.

Specification of Letters Patent.

Application filed June 14, 1909. Serial No. 501,892.

To all whom it may concern:

Be it known that I, CLARnNon B. HAN- RIGHT, a citizen of the United States, residing at Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Centrifugal Switches; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The invention relates to centrifugal switches.

While this switch is especially'intended for use in connection with single-phase induction motors of the type designed to be started with auxiliary windings in parallel with a working coil, or winding which auxiliary windings are cut out when a predetermined speed is attained, it is not limited to such" use, as it may be used for other purposes either to open or close a circuit when the rotary element to which it is attached attains or exceeds a predetermined speed.

Circuit interrupters, to be durable and reliable in operation, must act quickly so as to prevent injurious sparking, for the slow breaking of a circuit, and especially a circuit like that above mentioned, results in a rapid deterioration of the switch contacts.

The primary object of the invention is therefore to produce 'a centrifugal switch with movable contacts, the incipient movements of which, when a predetermined speed is attained, precipitate a rapid completion of the opening movements. It is also desirable that the switch should not close again until the rate of speed has been materially reduced, so that minor changes of speed, due to variations in load or other causes, will not produce a closing movement of the switch.

To this end the present invention contemplates the use of a contact member-occupyingclosed or open position when at rest and at low speeds, and a weighted pivoted member arranged to actuate the former by its movement under the influence of cen trifugal force when the predetermined speed is attained. The weighted member is so located with respect to the contact member, and cooperates with it in such a manner that its incipient movement under the action of the centrifugal force, precipitates rapid opening (or closing) movement of the con tact member.

In the accompanying drawing Figure 1 is a plan view of the switch in closed position showing diagrammatically the circuit connections for a single-phase motor; Fig. 2 is a plan view of the switch in open position; and Fig. 3 is a central vertical section through the switch. 3

As shown in the drawings, the switch comprises a plate or disk 1 which may be made of brass or any other suitable conducting material which is readily cut and bent into shape by means of punches and dies. The plate 1 is mounted upon a hub 2 but insulated therefrom by means of insulating washers 4 which are held between a shoulder formed on the hub 2 and a nut 6 screwthreaded upon the hub and retained in position by a set-screw 8. The hub 2 is adapted to be mounted upon a shaft 10 which is the main shaftof the motor. Pivoted to the plate 1 are two opposed contactor brush-carrying levers 12 and l lprovided with offset portions 15 and 16 respectively upon which contact blocks or brushes 18 and 19 respectively are pivotally mounted. Pivotally mounted upon the disk 1 are centrifugal brush-carrier actuating arms 20 and 22 which are provided at their outer ends with a seriesof washers 24 held in place by screws 25, and adapted to be thrown outwardly by centrifugal force when the -motor reaches a predetermined speed. By

varying the number of washers the critical speed may be varied; The arms 20 and 22 are provided with inwardly ext-ended horns 28 which are adapted to engage the opposing portions 30 of the brush-carrying levers 12 and 14. Coiled springs 32 and 34 are connected to the levers 12 and 14 and the corresponding arms 20and 22. These springs are attached to the levers and arms at points between their pivots and their ends which move outwardly; The movement of the levers 12 and 14 is limited by stops 36 and 38 which project upwardly from the plate 1 into the path of travel of said levers.

A pair of contact segments 40 and 41 are insulated from each other and mounted upon a stationary portion of the mot-or frame.

These segments are adapted to be engaged by the brushes 18 and 19 which are pivoted to the brush levers so that they may prop- I erly contact with said segments during their revolution about the same. The brush-carrier actuating arms 20 and- 22 while structurally independent of the brush-carrier levers, being separate devices, are operatively articulated therewith, so that while the carriers may (if desired) be balanced in their low-speed positions they are ada ted to be actuated, not by their own centrifugal force, but by the movements of their respective actuating arms.

The motor circuit includes a working coil 44 which is connected directly across the line wires {45 and 46, and also contains a starting coil 48 which is connected at one end to the wire 45 and at its other end to the segment 40. The segment 41 is connected to the line wire 46. During the starting of the motor the switch is in the position shown in Fig. 1 in which the starting coil. '48 operates in parallel with the working coil 44. lDuring the rotation of the motor the brushes'18 and 19 are maintained in contact with the segments 40 and 41 by the springs 32 and 34. When the motor attains a predetermined speed, the Weighted ends of the arms 20 and 22 fly outwardly, andthe horns 28 deliver a blow to the opposing portions of the bell crank levers 12 and 14, so that the incipient movement of the weighted arms acts to forcibly precipitate rapid. movement of the contact brushes from the segments 40 and 41 to quickly break the circuit through the starting coil, that is to say, the arms 20 and 22 being 1n unstable equilibrium as the motor speed approaches a certain critical maximum, the unbalanced centrifugal force, upon the attalnment of such maximum, will move the arms 20 and 22 suddenly outwardly so as to cause said arms to deliver blows to the bell crank levers 12 and 14. As the weighted arms move-outwardly, the leverage of the springs upon the arms and bell crank levers is reduced, as will be seen by reference" to Fig. 2. Thus a considerable force will be required todrawihe weighted arms nd the contact brushes inwardly against the se ments 40 and 41. This allows a considera le fluctuation in speed in the motor without causing the contact brushes to be brought into contact with the segments until a certain predetermined lesser or minimum speed of rotation is reached.

It is to be observed that the various parts of the switch may be formed of sheet metal, which is readily cut and punched into shape, thus afiording a construction which is durable, yet readily and cheaply manufactured.

Having thus described the invention, what is claimed is 1. A centrifugal switch having, in combination, a rotary support, a movable con tactmember mounted upon said support, independent centrifugal actuating means spring also being arranged to overcome the centrifugal force and suddenly move said centrifugal means when a certain-predetermined minimum speed of rotation is reached, substantially as described.

2. A centrifugal switch having, in combination, a rotary support, a contact member mounted upon the support, and independent centrifugal actuating means for moving the contact member comprising a Weighted member and a spring so arranged that the weighted member is held stationary by the spring until a predetermined critical speed of rotation is attained and is then released to move suddenly and strike a hammer blow upon the contact member, substantially as described.

3. A centrifugal switch, having, in combination, a rotary support, a contact member mounted upon said support, an independent centrifugal arm for actuating the contact member and a spring acting first increasingly and'later decreasingly to resist the actuating movement of the arm duringt-he approximation of starting speed to the operating speed, substantially as described.

4. A centrifugal switch, having, in combination, a rotary support, a pair of contact members mounted upon said support, and weighted arms pivotally mounted upon said support, and articulated with sa1d contact members to actuate them when the rotary member attains a predetermined speed, substantially as described.

5. A centrifugal switch, having, in combination, a rotary support, a pair of contact-carrying levers mounted upon said support, brushes on said levers, a pair of weighted arms pivotally mounted upon said support, and springs connecting the levers and the arms acting to exert pulls on the levers in the direction to oppose centrifugal force, substantially as described.

6. A centrifugal switch, having, in combination, a rotary support, a pair of contact-carrying levers mounted upon said support, brushes pivoted to said levers, a pair of weighted arms pivotally mounted upon said support, springs connecting the levers and the arms acting to exert pulls on the levers in the direction to maintain the contact members in closed position, and means for limiting the outward movement of said arms, substantially as described.

7. A centrifugalswitch, having, in combination, a plurality of contacts, a rotary support, a pair of opposed brush carriers mounted thereon, brushes mounted on said carriers, and cooperating with said contacts,

a pair of centrifugal brush carrier actuating ariiis,'-and;. prings and weights operatively relatedto' the arms to determine the critical speed at which the brushes are to be separated from the contacts, substantially as described.

8. A centrifugal switch having, in combination, a rotary support, a contact member mounted upon said support, and independent centrifugal actuating means for moving the contact member arranged to be held in unstable equilibrium as a predetermined speed of rotation is approached and then upon the attainment of said predetermined speed of rotation to suddenly move under the action of centrifugal force and deliver a blowglpon the contact member, substantially as described.

9. A centrifugal switch, having, in combination, a rotary support, a contact member mounted upon said support, independent centrifugal actuating means for movlng said contact member in one direction when a predetermined speed is reached and means for moving the contact member in the other direction when a lesser predetermined speed is reached, substantially as described. 7

10. A centrifugal switch having; in combination, a rotary support, a movable contact member mounted upon said support, independent means operated by centrifugal force for moving the contact member, said means being arranged to be held stationary until a certain predetermined speed of rotation is reached and then to be moved suddenly by an unbalanced centrifugal force to deliver a blow upon the contact member, substantially as described.

11. A centrifugal switch having, in combination, a rotary support, a movable contact member mounted upon said support, and a weighted arm pivotally mounted upon said support and articulated with said contact member to actuate it when the support attains a predetermined speed of rotation, substantial y as described.

12. A centrifugal switch having, in combination, a rotary support, a contact carrys ing lever mounted upon said support, a weighted arm pivotally mounted upon said support, and a spring connecting the lever and arm acting to exert a ull in the direction to oppose the centrlfugal force imparted to the wei hted' arm by the rotation of the support su stantially as'described.

13. A centrifugal switch having, in combination, a rotary support, a contact carrying lever mounted u on said support, a weighted arm pivotal y mounted on said support, a spring connecting the lever and arm and acting to exert a pull on the lever in the direction to maintain the contact member in closed position, and means for limiting the outward movement of said arm.

In testimony whereof I aflix my signature,

in presence of two witnesses.

CLARENCE B. HANRIGHT.

Witnesses:

I HERBERT A. BALCOME,

CARLTON L. KENNEDY.

Images