US2252796A - Control mechanism - Google Patents

Description

Aug. 19, 1 94 1. p WH|TTELL 2,252,796

CONTROL MECHANISM I Filed May 1, 1940 Patented Aug. 19 1941 I UNITED STATES PATENT orrlca ammo CONTROL MECHANISM Percy women, Philadelphia, Pa, alsignor to Philoo Corporation, Philadelphia, I'a. a corporation of Pennsyl 7 Application May 1, 1940, Serial No. 382,858

7 Claims.

This invention relates to new and useful improvements in control or adjusting mechanisms of the screw type and more particularly to such mechanisms adapted for use in instances or with apparatus requiring precision control or adjust ment;

In mechanisms of the type to which the pres-'- ent invention relates it has been found generally most convenient to obtain control orad lustment of-a movable member by means of a lowpitch rotatable screw element having a col-' lar or thelike threaded thereon and connected through suitable linkages tothe member to be controlled or adjusted so that the movement of said c'ollar along the screw element is imparted to said member. Anillustration-of the type or kindofuseto which mechanisms of the foregoing character may be put is the adjustment and control of the tuning unit or units of radio receiving sets wherein, for example, it may be desired to effect the adjustment of an axially movable member such as the iron core former.

Now in instances such as this, and particularly in the tuning of short wave radio receiving apparatus, the adjustment of such a core or other member is extremely critical, and furthermore,

of a tuned coupling trans- Another and equally important object of the invention is to provide an adjusting or control mechanism of the character set forth wherein novel means is provided for eliminating back lash or lost motion between the driving'screw and driven members of the mechanism.

Still another object of the invention is to provide a control and adiustingvmechanism embodying the characteristics and properties set tion through the driven member of the mechanism and showing the back lash or lost motion eliminator which constitutes a novel feature of the invention; and I r Figure 3 is an exploded ,view in perspective of the component parts of the device illustrated in Figure 2.

\ Referring nowvmore particularly to the draw when once adjusted it is important that the member be held in, that adjusted position against displacement as the result of reasonable vibra'-- tion.v Also, to obtain a critical setting or adjustment the control mechanism must havea smooth, positive drive.

However, control and adjusting mechanismsof the present type heretofore producedbave been manufactured with regard 'only to close tolerances in respect to each element or part ing, the control or adjusting mechanism of the present invention may-be stated generally to -comprise a manually rotatable drive shaft I having a screw section 2 thereon on which there is threaded an angular driven member or collar 3.

The screw section 2 of the shaft in preferably located along v-the mid-section of said shaft and the threads of said screw section usually are of relatively low pitch. The driven or collar member 3 in the form of the invention shown, is.

' with the result that there exists some play or lost motion between the driving and driven members of such mechanism audit is impossibleto obtain positige immediate axial advance of the driven member or, collar upon rotation'of'the angular in shape and in one leg 30 thereof is provided a tapped aperture 4 for threaded engagement with thefscrew section 2 of'the shaft I driving member or screw regardless of the direction of rotation thereof withthe result that critical adjustment is a matter of chance and the play or 10st motion existing between the drivenv and drivlngmembers eliminates all as-- surance that the adjusted member will remain inpathejposition to whichadjusted ifsublected rounding environment.

, Bearing theforegoing comments in mind,- the principal object of the presentfinvention is tov provide an adjustment and controlhmechanism' of the screw type which is characterized by its smooth, positivefdrive and wherein'axialmovemerit or advancejof the drivenjmember of the mechanism upon of the .driving' screw w in either directioaiafoositive'wd m to the-usual vibration of the immediate or sur- I movable bar 5. w Inthe illustrated invention to radio tuning units, "the longitudiwhich passes through said aperture. The other a leg lb of the collar 8 may extend parallel to the shaft I and is secured in a suitable manner to alongitudinally movable bar- 5. Both this Dan L and the shaft l. of course, are mounted in suitable bearing members (not shown), and it will be seen thatvwhen thewshaft l is rotated,- the connecting collar member 3 -is oaused,to move axially along the threaded or screw section: of said shaft carrying with-it the longitudinally application of the present naliy movable bar I may carry a number of brackets Otowhich maybe adjustably connected a number of iron cores l or other members by means. of screws I and lock nuts 0. As shown,

these cores or members I are for jmove- J ment;-ln the usual manner, axially withinthe tuned coupling transformers of a radio receiver, and in the drawing such transformers me diagrammatically represented by the coil forms III.

This type of tuning is so critical that even micrometer adjustment of cores I within the coil forms III will change the tuning of the transformers and hence the radio receiver, and it follows, therefore, that adjustment of these 'core members, I must be effected with precision and by means of a positive mechanical drive or ad'- justing mechanism.

In order to, obtain positive micrometer pretion 2 regardless of the direction of rotation of v the latter and regardless of the resistance to such motion afforded by the longitudinally movable bar 5. An effect of this compression of the spring I I will be the tendency of the members 3 and II to rotate relative to each other as the said spring I'I urges these members against the threads of the shaft screw section 2, but as previously stated, this action is prevented by the,

fact that the leg-Ila of member II seats upon the inner, surface-ofthe: leg 3b of the said memcision adjustment of such members as the cores I, it is necessary that all back lash or play be eliminated between the coupling collar 3 and the screw section 2 of the shaft I which exists as the result of normal manufacturing tolerances and the methods of manufacture necessarily employed to obtain commercial production of such mechanisms on an economical basis.

According to this invention back lash. or play' between the screw section 2 of shaft I and the coupling collar 3 is eliminated by effectively maintaining the threads of the driven collar 3 at all times against one face of the threads of said shaft screw section 2 regardless of the direction or speed of rotation of said shaft I, thereby positively fixing the position of said collar 3 and adjustable member I and resulting in 1 immediate positive micrometric adjustment of the collar and tuning unit upon rotation of the shaft I in either direction.

Toward accomplishment of the foregoing results, thereis provided an angular stabilizing member II positioned complementary to the coupling or collar member 3 upon the. screw section relative rotation of said collar3 and member II with respect to one another about the shaft I. In addition, the complementary member I I is interlocked with the coupling-or collarmember 3 byproviding an extension or lug at the free endof the leg Nb of the former which normally projects through suitable aperture I5 formed in the leg 3a of the latter;

A sleeve or like element I6 may be loosely mountedupon the shaft scre'w'section 2 and interposed between the legs 3a and Ila respectively of the coupling or collar 3 and its complementary member II. Also interposed between these sameleg portions of the members 3 and II r positively flxedand axial advance of said mem-.,,

ber 3. Relative rotation of the members 3 and II is prevented also by the interlock afforded between them by the projection or lug I4 of the latter which is fitted into the aperture I5 in the former.- Elimination of any possible play at this interlock is effected by the torsional forces in the spring I1 which maintain the relative angular positions of the members 3 and II fixed with respect to each other.

It is pointed out that the inclusion of torsional stresses in the spring member I'I enables the device or mechanism to function properly with but a small degree of compression therein,

not bind or frictionally resist rotation of the shaft I to any noticeable degree. Thus these forces in the spring I1 cause the members 3 and II to operate and function as a unit, sliding or telescoping longitudinally of the shaft screw section 2 and eliminating all play or back lash normally or otherwise existing between said screw 2 and the-member 3.

From theforegoing it will be? seen that the trol mechanism wherein two easily manufacturablestampings 3 and II may be threaded in interlocked relation upon the threaded portion 2 of a shaft I in such manner that the driven member 3 is continuously maintained against one face of the threads of said screw 2 regard less of the direction and rate of rotation thereof,

Thus the position of the driven member, 3 is ber 3 upon rotation of the shaft I is positive and immediate with the result that precision micrometric adjustmentand control of themember' 3 and a tuning or other gunitconnected thereto and surrounding the loose sleeve I 3 is a coiled spring I! which is .under compression and tends to move the members 3 and II in respectively opposite directions axially "along the shaft screw section 2s The spring I1 also has its end portions 18 and IS-respectively hooked over oppositel disposed edge portions of said members 3 an II"a s shown in Figures 1 andi2' and should be torsionally stressed to create forces urging the members 3 and II to rotate in-cpposite directions on and about the shaft screw section .2. It is pointed out that compression of the spring H, as aforesaid, should be sufficient to force and maintain the member 3 continuously against If axially expansible spring. interposed between one face-of the threads of the shaft screw 8e0- of such a unit and as well insuring that itwiil remain at that critical adjustment when sub jected to the reasonable vibrations of the en 'vironm'ent.

Although the invention is illustrated and described in conjunction with the tuning unit of a radio receiverv it will be obvious that said invention maybe otherwise employed as desired where precision micrometric adjustment and control of an immediate positive nature is required, and while a particular embodiment of the invention has been herein illustrated and described, it is not intended that said invention be limited. ,to such disclosure, butthat changes and modiflca-t tions may be made and embodied'therein within the scope of the annexed claims.

I claim: v I

1. Aprecision control mech ism of the character described including a rotatable drive screw," adriv enmember threaded on saidscrew, a stabiiizing member threaded on the's'crew, said membershaving a portionof each thereof extending at right angles to each other in abutting relation for preventing relative'rotation of d the members with respect to each other, and an and consequently the mechanism as awhole does presentflinvention provides an adjusting or conis obtained, enabling 'very critical adjustment Y -said driven and stabilizing members tending to eifect the axial separation thereof thereby to maintain the driven member firmly in engagement with one face of the threads on said drive screw so that lost motion and play between 'said driven member and said drive screw is elimiacter described including a rotatable drive screw,

adriven' member threaded on said screw, a

hated and adjustment of the driven member v axially of the drive screw takes place immediately upon rotation of said drive screw in either direction.

2. A precision control mechanism of the character described includinga rotatable drive screw,

a driven member threaded on said screw, a

stabilizing member threaded on the screw, said members having a portion'of each thereof extending at right angles to each other in interlocked relation with each other for preventing relative rotation of the members with respect to each other, and an axially expansible spring interposed between said driven and stabilizing members tending to effect the axial separation thereof thereby to maintain the driven member firmly in engagement with one face of the threads on said drive screw so that lost motion and play between said driven member and said drive screw is eliminated and adjustment of the driven member axially of the drive screw takes place immediately upon rotation of said drive. screw in either direction. t

3. A precision control mechanism of the character described including a rotatable drive screw, a driven member threaded on said screw, a stabilizing member threaded on the screw, one

of said members having a tongue interlocked with a slot in the other of said members for preventing relative rotation of the members with respect to each other, and an axially expansible spring interposed between said driven and stabilizing members tending to effect the axial separation thereof thereby to maintain the driven member firmly in engagement with one face of the threads on said drive screw so that lost motion and play between said driven member and said drive screw is eliminated and adjustment of the driven member axially of the drive screw takes place immediately upon rotation of said drive screw in either direction. I

4. A precision control mechanism of the character described including a rotatable drive screw, a driven member threaded on said screw, a stabilizing member threaded on the screw, one

of said members having a tongue interlockedv with a slot in the other of said members, and an axially expansible coil spring surrounding said drive screw and interposed between said driven and stabilizing members tending to effect axial separation thereof and with the opposite end stabilizing member threaded on the screw, said driven and stabilizing members having a portion of each thereof in abutting relation with the other and one of said members having a tongue interlocked with a slot in the other of said members, and an axiallyexpansible coil spring sur-.

rounding said drive screw and interposed between said driven and stabilizing members tending to effect axial separation thereof and with the opposite end portions of said spring engaging said driven and stabilizing members respectively and-tending to rotate the same in opposite directions, the construction and arrangement of said spring and the driven and stabilizing members being such that the said driven member is maintained at all times firmly in engagement with one face of the threads on the drive screw so that lost motion and play between said driven member, and said drive screw is eliminated and adjustment of the driven member axially of the drive screw takes place drive screw members with respect to each other, said abuttingportions being constructed-and arranged to maintain the thread engaging portions of said members perpendicular to the axis of said drive screw, and an axially expansible spring interposed between said driven and stabilizing members tending to effect the axial separation thereof thereby to maintain the driven member firmly in engagement with one face of the threads on said drive screw so that lost motion and play between saiddriven member and said drive screw is eliminated and adjustment of the driven member axially of the drive screw takes place immediately upon rotation of said drive screw portions of said spring engaging said driven and stabilizing members respectively and tending ,to rotate the same in opposite directions, the construction and arrangement of said spring and the driven and stabilizing members being such that the said driven member is maintained at all times firmly in engagement with one face of the threads on the drive screw so that lost motion andplay between said driven member and said drive screw is eliminated and adiustment of the driven member axially of the drive screw takes place immediately upon rotation of said drive screw in either direction.

5. A precision control mechanism of the charin either direction. l

'7. A precision control mechanism of the character described including a rotatable drive screw, a driven member of thin sheet material threaded on said screw, a stabilizing member of thin sheet material threaded on said screw, one of said members having aportion interlocked with a portion on the other of. said membersfor preventing relative rotation of the members with respect to each" other, said interlocked portions being constructed and arranged to maintain the thread engaging portions of said members perscrew so that lost motion and play between said driven member and said drive screw is eliminated and adjustment of the driven member axially of the drive screw takes place immediately upon rotation of said drive screw in either direction.

PERCY WHIT'I'EIL.

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