US2307567A - Switch closing mechanism - Google Patents

Description

Jan- 5, 19 3 T. R. COGGESHALL ETAL 2,307,567

SWITCH CLOSING MECHANISM Filed July 9, 1940 KEYED TO MOTOR SHAFT Inventors: Thellwell RCoggeshaH Herman BDhonau,

Carl Thu im. by a. Then- Attorney.

Patented Jan. 5, 1943 UNITED STATES PATENT OFFICE SWITCH CLOSING MECHANISM Thellwell R. Coggeshall, Bala Cynwyd, Herman B. Dhonau, Philadelphia, and Carl Thumim, Yeadon, Pa., assignors to General Electric Comx pany, a corporation oi New York Application July 9, 1940, Serial No. 344,530

7 Claims.

Our invention relates to operating mechanisms and more particularly to cam operating mechanisms wherein a motor-driven cam is operatively related to a thrust-transmitting structure for eflecting a working stroke. Specifically, this invention is an improvement on the arrangement disclosed and claimed in United States Letters Patent 2,131,603, granted September 2'7,

1938, upon an application of Carl Thumim and assigned to the assignee of the present application.

In the application of cam operating mechanisms of the above-described character to means, such as, for example, a circuit breaker, operable between open and closed circuit positions, it is desirable that the cam assume a predetermined angular position at the beginning of the closing operation with respect to the means to be operated. This is particularly important where the circuit-breaker mechanism is of the trip-tree type wherein a collapsible linkage normally maintained in the thrust-transmitting position by tripping means coasts directly with motordriven cam. The operating or working stroke in this case is the circuit-closing stroke at the end of which the motor is automatically deenerglzed. Since the closing stroke must be positive and last, a comparatively large amount of kinetic energy is stored in the rotating mass at the end of the stroke, so that considerable dimculty in stopping the arrangement at a predetermined D Sition obtains.

High-speed means have been proposed for stopping the cam in the same angular position by ailowing'it to overtravel and then providing means, such as centering springs and the like, to return the cam to the desired position. However, when mechanisms of this type are used in high-speed reclosing circuit breakers, the delay in allowing the cam to overtravel and then being reset by spring means or the like considerably increases the minimum reclosing time obtainable.

High-speed braking has also been proposed for stopping the cam but, due to the large amount of energy involved, damage to the mechanism often occurs since, in the prior arrangements,

the heavy torque end of the mechanism which it was desired to stop at a predetermined position was the one to which the braking means was applied. It would be desirable to provide an operating mechanism which is accurately timed from the high torque end thereof to stop the cam at a predetermined position without Accordingl it is an object or our invention to provide an improved cam-operating mechanism of uniformly high-speed and emcient operation which is simple and rugged in construction, reliable and positive in its resetting action and which overcomes ,the difliculties set forth above.

It is another object oi our invention to pro! vide a cam-operating mechanism for a circuit breaker requiring a predetermined angular position at the beginning of the closing operation in which the position is timed from the heavy torque end 0! the apparatus so as to apply high-speed braking means on the low torque end thereoi.

Still another object of our invention is to provide a cam operating mechanism'lcr an electric circuitbreaker which eliminates any possibility of nonuniform operation due to such variables as voltage and flux-decay conditions.

Further objects and advantages or our invention will become apparent as the following description proceeds and the features ofnovelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of the specification.

For a better understanding of our invention, reference may be had to the accompanying drawing in which the s'ngle figure thereof is a partly diagrammatic view of a cam cerating mechanism embodying the present invention shown in the open preset position in readiness for a working stroke. v

Referring now to the drawing, the operating mechanism illustrated therein comprises an electric motor in operatively connected through suitable gearing II and an operating shaft diagrammatically indicated at I! to a rotatable cam is. The cam I3 is provided with a suitably designed operating lace II and is secured to the shalt I! so as to be rotated in a counterclockwise dlrection, as shown by the arrow, upon energization of the motor Ill. V

The means to be actuateclis. generally indicated at It and may comprise the operating rod of an electric circuit breaker, for example. In the solid lines of the drawing, the rod ll is shown in the open position or the circuit breaker, not shown, and is operatlvely related to the cam it through a collapsible thrust-transmitting linkage indicated at ii. The linkage is normally held in the thrust-transmitting position. by a tripping means indicated at N. With the linkage in the open preset position shown, one revolution of the cam ll is eflective to cause a working stroke, the completion of which is indicated by a the linkage and operating rod in'the dotted line positions.

The thrust-transmitting structure can be oi any suitable design as will be understood by those skilled in the art. By way example, we

have shown a thrust-transmitting structure comprlsing a main toggle ll-il including a roller II which coacts with the operating iace ll of the cam ii. The toggle link i! is pivotaily connectedatoneendatlltoaguidelinkilhavlng a hired pivot 22. The toggle link II is pivotally connected at It to a lever 24, which is. in turn, pivotally connected at ll to the breaker-operat- 1118 rod ll. Thepivot II oithe tog lelink il isnorinallyhieidlinedbythetriiiiiil lmeansil-lo The tripping means It specifically comprises ail trippin toggle connected respectively to the main toggle pivot is and to a fixed pivot II. A latch 3i, which is rotatively mounted at a. is adapted to engage a roller 38 carried by an extensionll'olthemlelinkllhelm I! o! thetogglelinkll coasting withtheiixui pivot ll maintains the to gle in an underset position so that, when the latch Si is moved out o! restrainins engagement with respect to roller 13,

thetoggle 28-4! collapsesunderthethi'ustes- 80 erted at the pivot 2|. Thereafter, the toggle "-40 is no longer restrained in a thrust-transmitting position but is free to collapse. permitting reverse movement of the operating rod II to the solid-line position shown under bias oi. enersr- SI storage means ll, shown in the drawings; a suitable opening spring.

The latch II canbe controlled in any suitable manner as by the conventional tripping solenoid II or by independent manual means indicated at 40 The dotted position in the drawing illustrates the thrust-transmitting linkage in the restraining or closed-circuit position with respect to the.

operating rod it. In this position, the knee Joint 20 or the toggle "-48 is overset and engages a stop member 87. The linkage is thereby eiiectively locked in this position with respect to the thrust of spring 3| or other opening means tending to rotate lever 24 clockwise as long as the tog- 50 gle pivot It is held by the above-described tripping means ll. When the tripping means is actnoted in the manner above indicated, thetripping' toggle "-20 is no longer restrained by the latch II and buckles. permitting the toggle pivot 21 to move about the fixed pivot 22 in a counterelock- V wise direction under the influence oi the reacting forces, such as spring 34, tendin to cause openin: movement 0! the breaker rod II. when the toggle "-4! has collapsed and the lever 24 is rom tated counterclockwise to the solid position indicated in the drawing wherein the roller ll again engages the operating face or "low point 0! the cam II, the tripping toggle 28-4! is again stretched and extended so that the roller 3! rides g beneath the latch 3 l In this osition, the mechanism is reset and in readiness for another cam operation.

The motor-control system generally designated at 38 is adapted to deenergize automatically the motor'and other apparatus to be described hereinaiter after a working stroke oi cam i3 and to prevent a subsequent operation in the absence of a further positive control operation by the operator. This control system per se forms no part to ,se'r

oi the present invention and is described and claimed in United States Letters Patent to Thumim et aL, 2,004,478, granted September 28. 1931, and assigned tothe assigneeot the present application.

The control system comprises a controlled source oipcwer indiceted'at iron which the motor II and a solenoid I] to be described hetematter are energised through a suitable contactor ll-li'. The operating coil ll ior contactor "-4? is adapted to be energised throush an operatinl switch II and a limit switch ll. Accordingly. in order to initiate simultaneously the energisation of the motor it and solenoid II, switch 43 must be closcd,thereby' causing contaetorr li-ll' to close. This operation seals the circuit oi the contractor coil 42 through auxiliary contacts ll in so far as the operation or switch 4! is concerned so that the motor wfll not be deenergised in, the moddlc oi'the operating stroke by the'opening oi switch 43:.- i

The motor is automaticaiil doenerrised at the end oi the stroke by means o! a member ll secur'edto the cam shaft'll. The member ll is provided with a pin which picks up the loosely pivotedarm ll. At the end 0! the stroke, the member I! lifts the pivoted switch member It so as to o en contacts I and-cause deenergisation oi coil l! of contaetor ll-lif. At the same time, an auxiliary switch It is closed. thereby energising a coil Ii in the that the switch II is insir rh ini e noer' through the coacting armature ll. It isfthereiore. necessary that manually operable switch it be opened and again closed beiore a second operation can be initiated, therebypreoipding repeated operations or "pumping" 'oi'ihe nie'chiinlsin. It will, oi course, be understood that switch it reierred to hereinbeiore may be ja manually operable switch or may be controlled by suitable automaticmeans it desired. i

For the most etlcient operation oi cam ll it is clear that the "dwell' or low region shoufi, be limited to a On the other hand, it the extent or the low 1c! the cam is very small, the-cam must we tor the next Oberation very narrow limits. Due to inertia oi. parts; a certain amount of overtrsvel is unavoidable and the amount oi overtravel permitted determines the extent of the low region of cam it. Itis obvious iron the drawins cam tstol'iiiedat that-point, roller vll 0011K! i mint "oi the cam immediately m co r that, the ti'ipping means ll would immediately reset. This, thereiore. provides the main reason ior limiting the overtravel or the-cam since, it roller II were to drop to an intermediatepoi'nt on the cam race It instead or the "low" portion. the tripping means I. eouldnotbereset. Olcourse, lithecain were designed to have a "low" point or "dwell" period of degrees, the resetting oi the trippin means could saielybe accomplished but such can design is obviously unsatisfactory since but 180 degrees remain for the working phase. l'urthermore, with a longer "dwell" which would permit a wide range or positions where the cam could stop.

there would be a large variation in closing time.

which would be especially obiectionable where the circuit breaker is used for synchronising.

Various means have been employed for causmeans ii to reset at a predetermined point on the cam.

The present invention discloses a new mean for causing the cam to come to rest at approximately the same position after motor cutofl irrespective of the speed of the motor due to vari- 1g able voltage conditions and irrespective of the momentum o! the moving parts, thus permitting the "low" or ineiiective portion of the cam periphery to be reduced to a working minimum.

Furthermore, the present invention eliminates go the inherent delay due to overtravei and return of the cam but instead causes stopping of the cam at a predetermined point so that resetting of the tripping means I is assured. Furthermore,

the hazard of strained working parts and the u indeterminate final cam position due to unavoidable operation of the control motor on varying voltages is completely eliminated.

To this end, we provide means ior causing the cam is to assume a predetermined position at 39 the end of each working stroke which is determined by timing means at the cam end or heavy torque end of the operating mechanism so as to stop the high-speed low-torque end comprising motor i0, whereby no straining or danger to the working parts of the apparatus is caused while enabling the operating mechanism to be stopped in a very short interval of time. Accordingly, we have provided motor I with a multiple disk brake generally indicated at I! comprising al- 60 ternate plates I4 and I5, respectively, the former keyed to the motor shaft while the latter are keyed to the stationary support'li. End pressure applied to alternate plates I and II through thrust plate 81 causes an enormous brak- 4,5

ing action on the shalt of motor II. This pressure is exerted by a spring I acting on lever 50 pivotally supported at $0 and arranged to engage thrust plate 51. Multiple disk brake BI is so designed as to stop high-speed motor i0, which 50 preferably operates between 4,000 and 12,000 R. P. M., within one to six revolutions which, of course, means stopping cam I'I within very narrow limits,

Multiple disk brake 83 is released by means of 55 solenoid 40 which causes clockwise rotation of pivotally mounted lever 8! against the force of brake spring 58. Since solenoid 40 is energized at the same time as motor 10, brake i3 is always released when motor III is energized. In

order to time accurately the operating mechanism from the high-torque end-to cause accurate stopping of cam II at the end of the working stroke, we provide an auxiliary timing cam 5i provided with a notched portion "a cooperating 65 with the tip of lever 5!. when motor i0 and solenoid II are energized through motor control system 18, the tip 500 of lever I! is pulled away from timing cam II which is caused to rotate with cam shaft i2. Thereafter, even though mo- 7 tor II and solenoid 40 are deenergized, spring I cannot cause reapplication of multiple disk brake 53 until cam N has rotated suiliciently to allow tip 59a of lever 59 to reenter notch "a and moit is obvious that g which time brake BI is applied, thereby stopping cam i3 within very narrow limits.

The operation of the operating mechanism for one working stroke will be considered with reference to the positions of the various parts shown in solid lines in the drawing. By closing switch 41, contactor coil 42 is energized so as to close contactor li-Jl' and energize motor II and solenoid 40. This operation causes lever 58 to be removed from notch la of timing cam ii and releases multiple disk brake 53. Motor ll then drives cam ll through gearing ll, forcing the collapsible thrust-transmitting linkage I! upwards to assume the dotted position shown in the drawing. This results in the charging of opening spring ll and the closing of the circuit breaker, not shown, associated with operating rod II. when roller. I! reaches the highest point of cam II. the toggle linkage II-ll has passed above center and against the toggle stop 31 so that, through spring means 14, the linkage is locked in the overcenter position until trip latch 3| releases the latch for the opening stroke. Shortly after the toggle li-ll goes over center. the member 06 causes pivoted arm 48 to open limit switch I, whereupon contactor coil 42 is deenergized and contactor li-4i' causes deenergization of motor l0 and solenoid 40. The use of a separate switch for motor II and solenoid 40 embodied in contactor li-li' prevents motor i0 from acting as a generator when coasting to continue energization of solenoid l0. brake spring 50 tends to return lever is to its normal position, causing braking operation of multiple disk brake 53. However, timing cam H engaging with tip 59a of lever 50 holds brake 83 in the released position until cam 13 has rotated far enough for the roller I! to drop past the tail of cam i3. After a few degrees additional rotatlon of cam ll, lever 50 drops 01! the surface of timing cam 0i into notch Ila and the pressure of spring 58 is applied to the plates of multiple disk brake II, stopping motor ll within a few revolutions and, consequently, stopping timing cam ll within a very few degrees of rotation so as to position it accurately for the next operation of the mechanism.

In case the control circuit is lost during a closing operation. the pressure of breaker opening spring I applied through linkage II to cam I! will cause rotation of motor II and main cam II in a reverse direction to allow the breaker to open. During the opening motion of the breaker, pressure is withheld from the multiple disk brake I by timing cam II, which holds lever 58 in the released position until the breaker, not shown, has reached the open position. At this point, the tip Ila of lever ll drops 0!! timing cam Bi to allow brake ii to be applied, thereby positioning cam I! for the next closing operation oi the mechanism.

Thus, by insuring a predetermined starting position for cam II, a uniform operating time is possible as well as high-speed operation of the cam due to the fact that the tripping means is already reset. Furthermore, by eliminating the overtravel and return means of prior art arrangements, the speed of operation has been considerably increased, particularly when used in 0 connection with reclosing circuit breakers.

While we have shown and described particular embodiments of our invention relating to operating mechanisms, we do not desire our invention to be limited to the arrangements shown and detor i0 will coast until this condition occurs at 7B scribed for 1t m be obvious t those skmed in The' the art that changes and modifications may be made without departing from our invention and we, therefore, aim in the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of our invention.

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

1. In an operating mechanism comprising a motor and a rotatable cam driven thereby, means adapted to be actuated from one position to another position by said cam, said cam at the initiation of said operation being in a preferred predetermined position with respect to said actuated means, means for deenergizing said motor upon completion of said cam operation but prior to the time said cam reaches said predetermined position. and means operative upon further rotation of said cam to said predetermined position after deenerglzation of said motor for causing said motor to be stopped quickly so that said cam assumes said predetermined position.

2. In an operating mechanism for a circuit breaker, a motor, means actuated thereby for effecting in a cycle of operation a circuit-closing operation, means for deenergizing said motor at the end of said cycle, braking means for said motor released simultaneously with the energization of said motor, and means for causing said braking means to remain lnefiective upon deenergization of said motor until a predetermined M position of said first-mentioned means has been obtained;

3. An operating mechanism for a circuit breaker comprising a motor and a rotatable cam driven thereby, means actuated by said cam for closing said circuit breaker, a brake for said motor and spring means for holding said brake in braking position, means for energizing said motor and simultaneously releasing said brake for initiating the closing operation of said circuit breaker, means for deenergizing said motor at the end of said closing operation, and means for causing said braking means to remain in the released position upon deenergization of said motor until a predetermined position of said cam has been obtained.

4. In an operating mechanism comprising a low-speed heavy-torque portion including a cam member and a high-speed low-torque portion including a motor, means adapted to be actuated from one position to another position by said cam, said cam at the initiation of said operation being in a preferred predetermined position with respect to said actuated means, and means for stopping said cam in said predetermined position comprising braking means applied to said lowtorque portion of the apparatus in response to the position of the high-torque portion of the apparatus.

5. In an operating mechanism for an electric circuit breaker, a motor and a rotatable cam driven thereby, means adapted to be actuated irom one position to another position by said can: for closing said circuit breaker, a brake for said motor and spring means for normally holding said brake in braking position, a solenoid for releasing said brake, means for energizing said motor and said solenoid simultaneously for initiating the closing operation of said circuit breaker, means for deenergizlng said motor and said solenoid at the end of said closing operation, and a timing cam driven by said motor for preventing said braking means from becoming effective upon deenergization of said solenoid until a predetermined position cf said first-mentioned cam has been attained.

6. In an operating mechanism for an electric circuit breaker, a motor and a rotatable cam driven thereby, means adapted to be actuated from one position to another position by said cam for closing said circuit breaker, a brake for said motor, a pivotally mounted lever operatively connected to said brake and spring biased in a direction normally to hold said brake in said braking position, a solenoid operatlvely connected to said pivoted lever so as to overcome said spring bias and release said brake upon energization thereof, a control circuit for simultaneously energizing said motor and solenoid to initiate the closing operation of said circuit breaker, means associated with said control circuit for deenergizing said motor and said solenoid at the end of said closing operation, and a timing cam driven by said motor so constructed and arranged to cooperate with said pivoted lever and prevent said braking means from becoming effective upon deenergization of said solenoid until a predetermined position of said first-mentioned cam has been attained.

7. An operating mechanism for an electric circult breaker comprising a motor and a cam shaft driven thereby through reduction gearing, an operating cam on said cam shaft, means adapted to be actuated by said operating cam for closing said circuit breaker, said operating cam at the inltiation of said stroke being in a predetermined angular position with respect to said means, a brake for said motor, a pivotaliy mounted lever operatively connected to said brake'and spring biased in a direction normally to hold said brake in said braking position, a solenoid operatlvely connected to said pivoted lever so as to overcome said spring bias and release said brake upon energization thereof, a. control circuit for simultaneousiy' energizing said motor and solenoid to initiate the closing operation of said circuit breaker, said control circuit being arranged to deenergize said motor and said solenoid at the end of said closing operation, and a timing cam on said came shaft provided with a notch for preventing said pivoted lever from returning to said braking position upon deenergization of said solenoid until the end of said lever engages said notch, whereby said predetermined angular position of said operating cam is assured.

THEILWEIL R. COGGESHALL. HERMAN B. DHONAU. CARL 'I'HUMIM.

CERTIFICATE or CORRECTION. Patent No, 2,507,567. January 5, 1915.

TrmLLwELL R. COGGESHALL, ET AL.

01 the above numbered patent requiring correction as follows: Page 2, first column, lines 7 and 16, for "17-17" read --1'?-l8--; line 4-9, for the word "opening" read -oppos1ng-; and second column, line 20, for "moddle" read -middle--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of February, A. D. 1915.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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