US2549870A

US2549870A - Stopping mechanism

Info

Publication number: US2549870A
Application number: US653262A
Authority: US
Inventors: Fred C Wallace
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC; Federal Telephone and Radio Corp
Priority date: 1946-03-09
Filing date: 1946-03-09
Publication date: 1951-04-24
Anticipated expiration: 1968-04-24

Description

April 24, 1951 F. c. WALLACE I 2,549,870

STOPPING MECHANISM INVENTOR. F/f C. MMM/462' Patented` pr. 24, 1951 Fred C. Wallacd. New'r York, N. y.35., assigner. to@y Federal Telephone and Radio- Corporation, New-vYork, N. Y., a corporation of Delaware Application March-9,- 1946, SerialNo; 653,262

L Claims.. l

This invention relates to mechanismsfor'eifectin'g the stoppage yof--motor-driven -devicesa-nd, more particularly, to mechanisms-to eiiecting stoppage of such devices inagiven rotary sposition.'

In certain-.electric-rriotoroperated apparatus,

it is sometimes-desirablelto effectstoppage ofthe apparatus ina given-rotary position; Mechanisms-v designed for this purpose; available in the past, have beenfrequently inadequate insofar Ias they Werenot effective in producing positive 1 stoppage at .afgvenrotary point orin that they frequentlyr` caused undesired stoppage dueto an inherent tendency.

It is an object of thepresent invention-to provide a mechanism whicnwillenableva rotatable driven apparatus'to be stoppedin a given-rotary position.

It is another object to providea mechanism of theI type referred-towh-ich wil-l provide for-a positive stopping action;

It is still another object toprovidea stoppingI mechanism which is substantially effective tol cause stoppage at desired times only.

In accordance with the invention, the apparatus normally drivenin al predetermined direction by some driving meanssuch as electricY motor isY provided on the driving shaft witha stopping: mechanism, including a rotary cletent'elementY which is adapted to beengagedby astopping element arranged for separater rotary motion with respect to the driveshaft; The rotar-y mem- Y ber is adjustablein its krotary position so that the stopping. means may become eiectivein anyvde--v sired position.

TheV stopping element 1 or elements are "joinedfor. operation by means of'linkage providedfor that purpose which at the Sametime iseifectivein controlling the drive of the shaft, for example,

by controlling the power supply to the driving motor! in such a way as to produce'a slowdown and reversal thereof; In accordance withl another feature of the invention, a portion of.' the detent element is arrangedin sucheu way as-to be centrifugally affectedin its position. bywthe speed of rotation whereby its becomes, increasingly-effective as a detent as the speed is reduced.v

According to still another featureof the invention, the detent member isshaped such'as to be; of minimum stopping eiectivenessnduring the:

forward rotation of the shaft and assuming;v a maximum, eiectiveness. as-` the rotation of the shaft is reversed.

These andother features androbjects will be. more clearly understooduand other features-and 2 objectsmay become apparentl from the-followingfdetailed descriptionv of this invention,` reference beingv had to the drawings,` in-which:

Figui is an -illustration in schematic form-ofy v a motor anda-stopping mechanismin accordance withthe invention; and

Fig. 2 is a view in illustration-Lorastop-ping-y mechanism which isanfalternative-of-the one* illustrated in Fig. 1..

Referring to Fig. 11 of theattachedf drawings there is shown an electric motor- Iv'forl driving an appara-tus (which has` noti-been` shown)x and' which may for instance be the tuningfcondenser oi' a radio communications receiverf as v:may bei the case in scanningr reception. Thermotorl includesia field windingZ and an armature A3. Thel iield winding- 2 is connected across `a suitable power-f supply which is available atterfrninalsl 4- andn; The armature 3 is normallyconnected-'Ito-V thev power supply over a resistance 6 forming a Y portion of a voltage di-viderl 'i connected across the. line. controlled-by means of a make-and-break switch- 3, including contacts llandlll.A Contacts-9 and lill' i whenvmovedfromf. their normal .positions as indi cated willefect` aereversalintheLpolarity ofthe v power supply with :respect tothe' armature and' at thesame timeani-additional?resistance ll'is put. in. circuit' to'provide a reduced armature" voltage` The above described motor-also includes make-and-break contact-points l2, |3,--l4 and l5. The contacts aand irare mechanically linked-to a manually operable leverl `through linkagefl'l;

whereby they mayfbe movedfrom one'position.v .,tothe other by operation-of the lever IBL The motor l, for driving itsload. suchv asthe tuning'` element of a scanning receiver, as sug gested above, is provided-with -aA shaft I8, which is alsov arranged to-drive a' stopping mechanism l9vinithe direction of the arrow shownA thereon: Rctatably mounted on apivot'20 on the member i9. isza lever type member 2l having a stopping sur-face 22 on one side and alweightd portion 23 on the other side of the pivot. It will be apparent v lthat thepivoted lever 2| will'besubjectto centrifugal action as the motorfrotates `the means I9 to causethe portion'23 -and with it theY lever'2l toassume the positionzshownin full line-from thesposition indicatedzin broken lines `at 241into1 whichlit is normally urged' bymeansi-of a leaf. spring 25. secured between .the means19randthe. leverJZI. In .orderto effect thefstopping of the shaft-i I8 avr-comparatively large.gearz26' has.l been; provided adjacent to meansf. |-9 andhavingyseL-f v cured gthereon", two stopping; blocks.. 2lv .ands

The power supply to the: armature is- These

blocks

21 and 28 are connected to suitable linkage 29 which is turn is directly connected to the lever I6 referred to hereinabove for simultaneous radial movement of the

blocks

21 and 28 with respect to the gear 26 and the shaft I8. It is thus possible to place one or the other of these blocks in contact with the surface 22. The gear 26 may be rotated, for instance, manually by means of a knob 30 `on a shaft 3| through the medium of a driving gear 32 in mesh with the teeth of the gear 2S. The shaft 3| may extend as indicated by the arrow thereon to a rotary position indicator of the driven tuning elements, for instance, so that a desired rotary position of the gear 25 may be selected for a corresponding stopping position of the driven apparatus.

Thus, when it is desired to stop the mechanism either in the upper or lower positions as shown in the drawing the block 21 or 2B is moved toward the center of the gear 26 by operation of the lever I6 which at the same time acts to reverse and slow down the motor i. The reversal and slow-down of the motor as already indicated is accomplished by operation of the switch 8 which reverses the armature connections and at the Same time inserts the resistance |I into the armature circuit. As the speed of the motor is reduced the action of the centrifugal force on the weight 23 will be correspondingly lessened and the lever 2| due to the action of the spring 25 will assume the position indicated in broken lines at 24. As long as the rotation of the stopping mechanism IS is in thel direction of the arrow, the curved back surface 33 of the lever 2| will permit it to slide past the stopping blocks. As soon as, however, the rotation of the motor is reversed by means of the switch 8 the rotation of the lever 2|, now in the position shown at 24, presents the surface 22 in respect to the

blocks

21 and 28 in such a way as to engage them rmly. The shaft I8 will be stopped as soon as an engagement is made between the surface 22 and either` of the

blocks

21 and 28, the rotary position of the shaft being determined by the rotary adjustment of the gear 26. The motor remains continuously energized in the reversed direction so that the stopping mechanism may be continuously urged against the respective block regardless of what position it may be turned to by the operation of knob 30.

In Fig. 2, there is shown an alternate stopping mechanism which may take the place of that shown in Fig. 1 when, for instance, it is desired to stop the motor in only one and not in either of two given positions. In this instance the place of the

stopping blocks

21 and 28 is taken by a cam member 3d which is secured to gear '2B and is provided with an indentation forming a surface 35. Fixedly mounted on the shaft I8 is shown a lever 35 at the end of which an arm 31 is pivoted at 38. The arm 31 is provided with a stopping surface 3S adapted for engagement with the surface 35 and which also carries a weighted portion indicated at d0. The arm 31 is urged toward the periphery of the cam 34 by means of a spring il secured to the lever 36 and the arm 31. When the shaft I8 and the lever 3B are rotated in the direction of the arrow shown on the cam at'normal operational speed, the weight 4D keeps the arm 31 sufficiently far away from the peripheral surfaceof the cani s'o that it will not engage the surface 35, analogous to the actiondescribed for Fig. 1. to stop the motor, the motor is reversed, so that a quick stop may be` achieved, and' energized for When it is desired slow rotation in the opposite direction until the detent at 35 and the surface 39 engage whereby the surfaces are held in contact. In the modification of Fig. 2 it is not necessary to provide a lever as shown at I6 in Fig. 1, since the operation merely of a switch corresponding to that indicated at 8 will stop the mechanism in the single given stop position.

It will be apparent from the above description that the stopping mechanism herein disclosed avoids undesired catching and jamming while preserving mechanical simplicity and at the same time provides for positive action when stoppage is desired.

While= the above is a description of the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only 'by way of example and not as a limitation on the scope of this invention as defined in the accompanying claims.

I claim:

1. For use with a rotatable device which it is desired to stop at any given rotary position; a stopping system comprising shaft means for driving the device, detent means including a rst member mounted on said shaft and a detent pivotally secured to said first member, stop means mounted for movement into and out of the path of said detent, means for adjusting said stop means to any predetermined rotary position, means for holding said stop means and said detent out of engagement with each other during normal operative rotation of said shaft, means normally urging to effect an engagement between said detent and said stop means, and means for controlling the rotation of said shaft, said stop means including stopping blocks radially movable with respect to said shaft, and said control means including an electric motor having speed and direction control switch means, and means for effecting simultaneous operative movement of said blocks and of said switch means.

2. For use with a device which it is desired to stop at any given rotary position, a stopping system comprising shaft means for driving the device, detent means including a first member on said shaft for rotation thereby and a second member pivoted on said rst member having a detent surface, a stopping block arranged for radial movement with respect to said shaft into and out of engagement position with said detent surface, spring means between said first and second members to normally urge the latter into an engaging position, a weighted portion on said second member for holding said second member out of engagement with said block by the action of centrifugal force upon said weighted portion during normal rotation of said shaft, means for selectively, rotatably, adjusting the position of said block relative to said shaft, driving means for said shaft, and a mechanism for simultaneously effecting the radial movementl of said block and a reversal of said shaft.

3. For use with a device which it is desired to stop at any given rotary position, a stopping system comprising shaft means for driving the device, detent means including a first member on said shaft for rotation thereby and a second member pivoted on said first member having a detent surface, a pair of stopping blocks arranged for radial movement with respect to said shaft into and out of engagement position with said detent surface, spring means between said first and second members to normally urge the latter into an engaging position, a weighted portion on said second member for holding said second member out of engagement with said blocks by the action of centrifugal force upon said Weighted portion during normal rotation of said shaft, means for rotatably adjusting the position of said blocks relative to said shaft including gear means mounting said. blocks and means for selectively adjusting the rotary position of said gear, an electric motor for driving said shaft, motor circuit control means for controlling the speed and rotary direction of said motor, and a mechanism for simultaneously effecting the radial movement of said blocks and a reversal and slow-down of said motor.

4. A stopping system for use with a rotatable device which is desired to be stopped at any given rotary position, comprising means to drive said device including a shaft, a member carried by said shaft, a detent pivotally supported on said member, a rotatable member mounted for rotation coaXially of said shaft, a stop carried by said rotatable member, means for rotatably adjusting said rotatable member, said stop being 6 mounted for movement radially of said rotatable member and the means to drive said device including an electric motor having a speed and direction control switch and means for effecting simultaneous operative movement of said switch and of radial adjustment of said stop.

FRED C. WALLACE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,272,337 Harvey July 9, 1918 1,834,448 Ellis Dec. 1, 1931 1,848,761 Wilson Mar. 8, 1932 1,871,672 Ellinger Aug. 16, 1932 2,351,997 Morrill June 20, 1944 2,454,789 Frink Nov. 30, 1948 FOREIGN PATENTS Number Country Date 583,250 France Jan. 8, 1925