US934889A - Step-by-step motor. - Google Patents

Description

In C. DVDSON. STMBY-STEP MTOR.

APPLIGATION FILED JULY 1, 1.907.

@,hggg www. sept. '21, m09.' gemma-SHEET 1.

L C. DVIDSN. STEP-BY--STEP MOTOR.

APPLICATxoN FILED JULY 1,1907.

. atened Sept. 21, 1909.

2 SHEETS-BHEBT 2.

ATTOHNEYSI I so that Whenever the spring barrel turns in a contra-clokwise direction, according to Fig.' 3, its rotation is stopped abruptly by the pawl 23.

A leaf spring a is mounted upon the gear wheel 13 and engages the pawi 20 so as to force its innerv end downward and facilitate the entrance of this end vinto the A ratchet wheel 27, rovided with notches 28,. is'smounted loosey u ony the axle 14,

, transmitting and is engaged by a paw 29. A beveled plate 32 is mounted rigidly upon the spring barrel 17. 'This cam at one of itsaends is provided with acomparatively thin portion 30 and its other end is provided with a pivot pin 31 forssupporting the pawl 29. A leaf 'spring 33gis connected at its inner end with the'spring barrel, its outer end lengaging the pawl 29 and forcing the same gentlyA against the' surface of the ratchet wheel 27,. A Igeagyiiheel 3d is connected ri idly with the ratchet wheel 27., both of said members .considered as a unit, being loose relatively to the stationary shaft le. The gear wheel 34; meshes with a larger gear wheel 35, the latter being rigidly mounted upon a shaft 36. A' swinging arm 37 is journaled upon the upper portion of the framework and provided with a detent 37a. This swinging arm is normally drawn to the right by a spiral spring 38. This arm 37 carries a pawl 39 which is pressed to the left by a spring flO. The detent 37 a and awl 39 engage respectively the opposites ges of one of the s okes ofthe wheel 35 and thus periodica ly lock this wheel against accidental rotation either forward or backward.

pulley 41 is mounted rigidly upon the revoluble shaft 36, and may be used for power from the machine. The lower vend o the arm 37 carries a horizontal portion t2, and from the latter de ends a wedgeshaped lug 113. This lug is isposed' partially within the ath of the cam 32 so that when the s ring arrel 17 carrying the cam 32 is rotate the cam 32 ushes the lu e3 to theleft and caus the etent 37B" an the pawl 39 to lock the r ar Wheel 35.

Theo eration of my vice is as follows: The pul ey 41 is connected themechani ism to be driven, and the angular end 16 vof the axle 14C is turned, if'need be, until the .spring 13 acquires a proper degree of tension. The electric motor 5 is next started into action; the reroluble shaft 7 being thus /set in motion, lthe worm 8 turns the gear' Wheel 9 steadily in a contra-clockwise direction, according to Figs. l and 3. -I-ence,A the pinion 11 causes the gear 13 to turny in a clockwise direction; according to these a figures. The-rotation of the gear Wheel 13 is steady. The pawl 20, carried by the gear Wheel 13, is normally inv engagement with the notch 19. As the gear Wheel 13 turns, however, carrying with it spring barrel 17 by pawl 2O the projecting portion 21 of said pawl is brought against the stationary trip 22, and the -pawl is thus caused to rock. Thls releases the spring barrel 17, and the latter being under tension from the s iral i spring 18, turns in a contra-clockwise lrection, accordinr to Fig. 3; it makes' almost a com lete revel cate in Fig. 4, by .the 'lodgment of the notch .19l against the inner end of the pawl 23. During this time the motion of the gear wheel 13 isnot interfered with, and a moment afterward, the inner end of theA pawl 20 lodges in the notch 19 and again turns the spring barrel around until the'pawl 20 is again tripped. These' motions .of the spring barrel 17 continue so longas ower ution and is stopped, as indiis supplied to the electric motor 5; t iat is i to say, the spring barrel 17 turns slowly in a clockwise direction for substantially a revolution at the same rate of speed as the'l gear 13,`and then the spring barrel suddenly turns in the opposite direction, being brought abruptly to a. stop and instantly resumes itsl slower travel as before. Each time the spring barrel 17 performs this reflex movement under impulse of the spring` 18, the cam 32 engages the lug 43 and, being beveled, moves the swinging arm 37 to the,A

left, vaccording to Fig. 2, so that the pawl 39 locks the gear wheel 35. The spring 38,'

ulling constantly upon the arm 37, releasesV 1t from the wheel 35 as soon as ithe blade 32 turns a suiic'ient distance teclear the lug 43. .The result is that this gear wheel, the shaft 36 and pulley 41, are periodically locked'and released in accordance with the intermittent motion conferred upon them. The action of' the machigeis thus rendered positive. Eachtimethe s ring `barrel 17 moves neder the` impulse o the spring 18, the pawl 29 1gibeing mounted upon the cam 32 which yis Xed uponthe spring barrel)' engages some one of the notches 28 and turns the ratchet wheel 27,' Th-iswheel being fixed relatively to the gear-1 wheel 34:, transmits the intermittent lmotion through .thisr gear Wheel to the'gearwheel 35. i

From the above it will be seen that theflf train of gearing extending from the motorij to the 4spring' barrel, is composed of revoluweisses members all move intern'iittently. rihe net result is that the pulley atl is stationary most of the time., but at regular intervals, receives impulse motions which send it spinning always in the same direction, and its motion, after receiving each impulse, is suddenly ln'ought to a stop. v

it is desirable that the gear wheel shalt always move the same distance1 whenever acted upon through an impole tronrthe gear wheel 3l and spring barrel. rthis is especially necessary 1n instances where a movable member, driven by the gear .wheel 35, must always travel a given distance'and thus have a true and positive step-bystep motion. It is also desirable that the gear wheel 35 shall be locked positively at'ter performing' cach of its movements and re lcased positively just betere each ot its movements.

In order to attain the two objects just nientioned,` it is essential that there shall be a detinite nrithen'iatical relation between thc number ot' teeth carried by the gear wheel. the number ot' notches carried by the ratchet wheel 2T and the munber ot' teeth upon the gear wheel 3l. For instance, it the gear wheel 311. has thirtysix teeth and the ratchet wheel I! has six notches, the gear wheel 35 may have sixty teeth. in this instance the gear whee 35 will turn exactly one halt revolution alter each im pulse, and will then be locked positively until released in time for the next impulse. The gear wheel 3ft makes not quite a complete revolution for cach impulse given by the spring barrel. ln the drawings, the gear i whee 3lhas thirty-six teeth and turns t'or each step exactly tivesixths of a revolution, thus leaving six teeth idle. The space occupied by these six teeth represents the degree et imivement necessary to allow the gear ifi to overrun the ratchet wheel 27 during the time required t'or tripping the pawl, release ot' spring; barrel li', and rctlex rotation of the spring barrel until caught. by the. pawl 223. t`ontrast Figs. El and -t.

llavingf thus described my invention, l

'- claim as new and desire to secure by Letters Patent z 1. The combination ol` a normally stationary axle, a barrel rcvolnbly mounted thereupon and provided with notches, a spring' connected with said barrcl.and with said axlc 'for thc purpose o't' turning said barrel relatively to said axle` mechanism including a pawl t'or applying powcr to said barrel 'lor the purpose ol winding' said spring, a stationary trip member disposed partially within the path olI travel ot' said pawl tor the purpose ot releasing' said pawl from said barrel, thus allowing` theI latter to turn under the impulse 'oli said spring', al

pawl lor engaging' another ol' said notches and thus stopping,r rotation of Said spring barrel from the impulse, ot said spring,giar ing connected with said spring barrel so as to be, driven thereby, and mechanism for periodically lockingr and unlocking' said gearing.

2. The combination of a normally stationary axle, a cog wheel revolubly mounted thereupon and driven continuously, a barrel revolubly mounted upon said stationary axle and movable relatively to said cog wheel, a spring connected with said barrel and with said axle, means t'or periodically connecting said cog wheel to said barrel so as to temporarily. turn said barrel againsty the tension of said spring, mechanism for periodically liberating said .spring barrel from its connection with said cog' wheel so as to allowsaid spring,- barrel to turn under impulse otsaid sprino', means t'or limiting the rotation ot' said spring barrel relatively to said stationary axle when released, a ratchet wheel mounted upon said axle and rcvoluble relatively thereto, said ratchet wheel being connected with said spring;I barrel and driven thereby, a ,gear member connected rigidly with said ratchet wheel, gearing' connected with said ratchet wheel and driven thereby, said gcarimeA inchnlini,y a driven member tor transmitting' power trom the motor, and mechanism tor locking said. last-mentioned driven member a't'tcr cach ot' its movements.

il. The combination ot a normally stationary axle, a barrel rcvolubly mounted thereupon and provided with notches, a spring' connected with said barrel and with said axle for the purpose ot turning said barrel relatively to said axle, means t'or applying power to said barrel so as to wind said spring', said means including' a pawl normally engaging' some one ol said notches ot said barrel, mechanism 't'or periodically tripping' said pawl so as to release said barrel therefrom, thus allowing said barrel to turn bacltward under impulse otl saidspring. and a second pawl tor engaging another ot' said notches andthus stoppingV rotation ol said barrel.

't. 'l`he combination o'tI a normally stationary axle, a cole' wheel revolubly mounted thereupon and driven continuously, a barrel mounted loosely uponsaid stationary axlc and movable relatively to said cog wheel, a spring connected with said barrel and with said axle, means tor periodically connecting' said cog wheel to said barrel so as to temporarily turn .said barrel against the tension ot said s1 i'iii;'.'t|'ip mechanism i'or the pul'- pose ot'v periodically libciating said spring barrel trom its col'mcction with said cog wheel so as to allow' said spring' barrel to turn under impulse ot said spring, means tor limiting the rotation ol' said spring bar- 'llO released, a ratchet Wheel mounted upon said A axle and revoluble relatively thereto, said ratchet Wheel being connected 'with said spring barrel and driven thereby, and a gear member connected rigidly with said ratchet wheel.

In testimony whereof I have signed my' name to this specification in the presence of two Subse1il: i1i, Witnesses.

LYMAN CRITTENDEN DAVIDSON. `Witnesses:

TQ/VALTON HARRISON, EVERARD B. MARSHALL.

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