US2435291A - Sewing machine - Google Patents

Description

`lFeb. 3, 194s. B A, SCHM@ 2,435,291

` SEWING MACHINE Filed Aug. 6, 1945 '3 Sheets-Sheet l N -i m w gli ,Iqlld-.v m l @Nv i ,Hz M -Huw MN, n. 1 -J *um NH QQ I I -l-H'Ulll m Mmm, QN m m QM. mm. fm Mw/mr QN rl l r `m QW un ,.Hu-

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Filed Aug. e, 1945 s sheets-sheet 2 i B. A. SCHMITT SEWING MACHINE Feb. 3, 1948.

Filed Aug'. ek,- 1945 5 SheetsLSheet 3 Patented Feb. 3, l 948 UNITED STATES PATENT oFFlcE SEWING MACHINE Bernard A. Schmitt, Chicago, Ill. Application August e, 1945, serial No. 609,116 9 claims. (c1. 11a-21o) This invention relates to sewing machines of the household type and more particularly to novel drives for stitch-forming and feed mechanisms therefor together with improvements in stitchlength adjusting means.

It is a general object of the present invention to provide a novel and improved household sewing machine.

More particularly, it is an object of the invention to provide, in a sewing machine of the type described, novel and improved drive means for rotary stitch-forming mechanism of the one-toone ratio type whereby variable speed motion thereof is effected during each revolution as required for cooperation with the needle and for the proper looping of the needle and bobbin threads.

Another important object of the invention consists in the provision of unique means for providing from the variable speed rotary hook drive shaft the horizontal component of motion for the feed dog.

A still further object of the invention consists in the arrangement of novel stitch length-adjusting meanswhereby the driving connection between the rotary hook drive shaft and the feed shaft may be regulated to result in the desired length of stitch.

An important feature of the invention resides in actuation of the feed shaft from the variable speed hook drive shaft through the agency of a cam and followers.

Another important feature of the invention resides in the drive between the main shaft and the'rota'ry hook drive shaft which eliminates most of the usual vibration by dispensing with the customary crank on the main shaft.

Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specification wherein is disclosed a single exemplary embodiment of the invention with the` understanding that such changes and modifications may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawings:

Fig. 1 is a front elevation of a sewing machine constructed in accordance with the present invention, certain portions of the frame casting being broken away to permit illustration of the interior working mechanism;

Fig. 2 is a bottom plan View of the machine of Fig. 1; 1

Fig. 3 is a vertical section taken on broken line 3 3 of Fig. 1 looking in the direction of the arrows;

Fig. 4 is a left end elevation of the bed and mechanism beneath it;

Fig. 5 is a fragmentary vertical section taken on line 5 5 of Fig. 1 and illustrating the feed shaft connecting-rod drive, and

Fig. 6 is a fragmentary horizontal section on line 6 6 of Fig. 3, looking in the direction of the arrows and illustrating the pivoted fulcrum for the main drive connecting-rod.

In order that a household sewing machine may be commercially successful it should be low in cost, compact, light weight and simple in operation, as nearly vibrationless as possible, and it should operate with ease and quietness. To maintain low cost the machine must be of few parts and these must be of simple construction requiring the minimum of machining and adjustment during assembly. Quietness, lack cf vibration and ease of"operation flow from accuracy, good design, careful balance and a reduction in the number of parts, bearings and the like. The machine of the present invention is unique in combining all of these important functions, and while it has been shown with plain bearings and other simple constructional features it can, where cost is of less importance, be equipped with ball or roller bearings to further reduce the effort necessary to drive it and to decrease the requirements for periodic lubrication. The machine illustrated plate is incomplete in that no mechanism is shown inv the head other than a rudimentary needle bar. No invention lies in unillustrated portions of the machine and they are assumed to be of conventional construction.

Referring now to the drawings, and particularly Fig. 1, it will be seen that the conventional bed plate lil is equipped with an integrally cast hollow standard I 2, supporting the integral horizontal arm i3 mounting the head it in which the needle bar I5 is reciprocated by suitable mechanism. Appropriately journalled in the head is the horizontal main shaft Il comprising a simple straight rod with no cranks or the like whereby it may be inserted through the end bearing i6 man extremely simple manner and then engagedgin the head drive. Except for the mechanism in the head i4 it mounts only the single, fully balanced spur gear i9 secured thereto by set screw 20. This gear meshes with one of equal diameter at 2|. rlhe hub 22 of gear 2| abuts against boss 23 integral with the standard and horizontally drilled at 24 to lreceive the stem of a tapered spindle forming the bearing for the hub 22. The spindle is adjustable in the bore 24 by means of the screw shown to provide take-up for wear and to simplify initial assembly and adjustment.

A simple crank-pin having a conical head 26 is bolted into the disc of the gear 2l eccentric to the bearing thereof and forms the upper connection for the main driving connecting-rod 28.

This connecting rod 28 is adapted to drive the rotary hook drive shaft 30 extending longitudinally of the machine beneath the bed plate and having bearings at opposite ends in bearing members 31 and 32, respectively, which are integral with `or suitably attached. as shown, to the'undelside of the bed plate. This horizontal shaft drives the vertical shaft 34 of the rotary hook or stitchforming device 35 through suitaltilyv meshed, oneto-one ratio, spiral gears 36 and 31. The vertical shaft 34 is journalled in forks 38 and 39-ofthe bearing member 3l suitably positioned to locate the rotary hook entirely-'to the right of the needle axis.

The details of the stitch-forming mechanism are reserved for separate applications for patent, but it should be pointed out here that stitchforming mechanism of the rotary, one-to-one ratio, vertical-axis typerequires non-uniform or variable speed drive so that at portions-:of the rotation of the mechanism the speedis'r'naterially reduced to permit the entrance of the needle and the looping of the needle and bobbin threads. This irregularity of drive is achievedv through the connection between themain shaft andV theV rotary hook drive shaft 30 by way-of the connecting rod 28, which connection will now be described.

The shaft 30 has pinned v to it, on the right side ofbearing 32; an, arm 4l; slotted radially asat 42, seen best in Fig. 3, and in this slot fits a block Iv4.3 pivoted at 44 on the lower endof connecting; rod 28; vIntermediate the ends of the connecting rod and substantially closer to the lower endl is a fulcrum for the same comprising gr-oovedrfblcck 45, pivoted on ahorizontalsh'aft or stern 46, freely journalled in bushing 4l adjustably held in clamp 48 intermediate the ends of` bridge50` extending across the opening I 'in the bed plate beneath the standard.

Reference should be hadfto Fig. for the detail construction of this assembly. The connecting rod28 will be seen to have tapered or converging sidesfwhich slide in the similarly shaped channel or groove in the'block 45 whoseintegralstem 46 is seen in bushing 41. It will `be appreciated that wear between the connecting rod and the Walls of the groove 45 can becompensated for by adjusting the bushing 48- toward the head of block 45, the under surfaces of which bear on the left Yend of the bushing. Since the connecting rod does not bottom in its groove this insures against any lateral play andr eliminates noise as well as permits compensati-on for wear and simplies initial adjustment. i

If desired, the block 43 and the groove 42 in arm 4l may be similarly arranged. It will be appreciatedrthat proper design of the connectionsV just described will permit the desired non-uniform motionof the rotary hookdrive shaft,

Y'The rotary hook drive shaft 30 extends to the left beyond the gear 36 and is there tted with a tapered eccentric 5D, having a collar 5l integral therewith and adjustable on the shaft longitudinally and locked in position by a set screw as shown. This eccentric is straddled by the arms of fork 54 on'one end'of-feed'dog carrier 55, whereby aV vertical-component ofm'otion is'contribut'ed so that the feed dog 56, suitably attached to the carrier, may be projected above and Withdrawn beneath the surface of the bed plate for feeding the fabric beneath the presser foot for cooperation with the needle. The feed dog operates in a suitable slot, not shown, in the bed plate.

The horizontal component of movement for' I thefeed dog carrier 55. The wide spacing of the arms 66 insures against. any lateral movement of the; carrier 55 so that the; forked end. is constrained to movein axplane'andtraverseian appropriate path: on the tapered surface of the-eccentric. Longitudinalg adjustment of theeccentri-c takes care -of wear onA thefforksand'eccentric surfacev so that, a tight'fitis always insured;

@Scillationis impartedfto feed shaft 60 through the agency of a substantially horizontal. connectingfrod pivotetd :at 69th thelower end'of a vertical lever' arm; 15: extending downwardly from theshaftlll;Y Theenlargedoppositeend 11| of theconnectingerodiits overv the. tapered heartshaped cam;V 12z mounted-,for rotation with the shuttle;shaft"30.

The connecting rod is preferably a-,sheetl metal stamping. so insteadv ofbeing' forked the upper end is closed as shown for greater strength. and lightnessv and. hasl intu'rned, opposed;y straight flanges 13; forming-z the followers for the cam; These rflanges conform` to the taper of the; cam andfareparallelfto the-axis tof the connecting rod as shown. The taper of the cam is for thesame purpose as the taper in; eccentric 50-to=provide for-simplefinitial setting and adjustment for wear by longitudinal movement of the'cam.

i If the connecting rodwerefree'on the: cam it is clear that it would `not impar-t any movement to arm 10 and shaft 60 because of the-:paralleledispositionof the flanges 13- to the axis-of the yconnectingsrod; If, however, restraint .is'givento the Vertical: movement. of: the head. of the connecting rod, then a horizontal component may be imparted toitsv motion. Such restraint is effected by meansfiof; link 15 pivotedtotheenlarged head near its upperleft-.hand` corner"aszvieweddniliigz 5 as atv 165. The link is short. and'itsfoppositeend is carried on a fulcruml; It willbeclear that if this fulcrum` is Lpositionedf'so that the-link `is substantiallyf' parallel to the flanges 13- that -n`o= motion. will be 'impar-tedto the feed shaft. butin.' las shown; the linkl has an angle V-of lgreater than zero and 'less than =90" with the` axis of? the connecting rod 'thenlsomeioffthe vertical-movement imparted to the-head bythe carn is converted into 'horizontal movement. lBy -changingthepos'ition of the fulcrum 1B `the amountfof-movernentimparted to the feed shaft is regulatable, and this provides a simple means for manually adjusting the length of stitch or the quantity offabrie 'fed per stroke of the feed point.

In order to control the path of movementv of the adjustable vfulcruml 4it `is aIso-attachedfto one end of a second link-T$of4 substantially 'the same lengthas link 15; rIhe opposite-endofflink 19 is fulcrumed at 80 on boss 8l extending-from s. bearing member 32. This boss is so positioned that the pivot 8B is substantially in alignment with pivot I6 in one of the intermediate positions of the connecting rod head. The path of the fulcrum 78 will be seen to be confined to an arc having a radius equal to the length of link 19. Movement within this arc to the desired degree is effected by means of a positioning link 85 best seen in Fig. 3. It is journalled on fulcrum 'i8 and its opposite end is pivoted at 8e intermediate the ends of an adjusting lever 81. Theinner end of this lever is fulcrumed on a boss 88 on the inner wall of the standard by means of a screw 89 and spring washer for providing friction Vto hold the lever in any position set. The outer end of the lever provides for fingerv tip adjustment and -extends through a slot Si! in the front wall of the standard'and passes alongside of graduations, not shown, on the vslotted cover plate 9|, for designatingV the length of stitch.

The solid lines in Fig. 3 show the maximum adjustment of the fulcrum 'i8 in one position and the dotted lines in the opposite. Intermediate these two positions is the point of substantially zero movement of the said shaft so that both forward and rearward movements can be imparted to the feed dog from zero to maximum stitch length.

The mechanism just described provides a simple means for driving the feed shaft to the extent desired from a parallel shaft having full rotation but irregular motion. The adjusting lever effects both changes in stitch length and reversal l of direction of clothfeed by changing the amplitude of oscillation of the feed shaft and its phase in relation to the variable speed rotary shaft.

I claim:

l. In a household type sewing machine, in combination, a bed plate, a standard, an arm and a needle-bar supporting head, a main shaft extending through the standard and arm into the head, a rotary hook drive shaft extending beneath the bed plate parallel to the main shaft, means to drive said hook drive shaft with a oneto-one ratio from the main shaft, an oscillatable feed shaft substantially parallel to the hook drive shaft, a cam on the hook drive shaft, a connecting rod having straight, opposed follower surfaces engaging said cam in planes parallel to the axis of the rod, means pivoting the opposite end of said rod to an arm on said feed shaft, an eccentric on said hook drive shaft, a feed dog carrier having a fork at one end engageable with said eccentric and having the opposite end pivoted to an arm on said feed shaft, a link pivoted to said connecting rod near one of said follower surfaces, a fulcrum for the opposite end of said link and means to adjust the position of said fulcrum to vary the amount of axial movement imparted to said rod by said cam.

2. The sewing machine as claimed in claim 1 in which the drive between main and rotary hook drive shafts includes a crank separated from the main shaft by a gear train.

3. In a sewing machine, in combination, a straight main shaft, a rotary hook drive shaft adapted to be driven at a one-to-one ratio from the main shaft, a slotted arm on said hook drive shaft, a connecting rod having a pivoted block on one end thereof slidable in said arm, an intermediate fulcrum for said connecting rod having longitudinal sliding engagement therewith, a crank disc driving the opposite end of said the end thereof beneath the standard, a gearA journalled on an axis parallel tosaid shafts, a spindle for said gear carried by a wall of said standard, a gear on the main shaft meshing with the rst gear, an eccentric pin on said rst gear; a connecting rod having one end pivoted on saidl pin and having a block on the opposite end slidable in said slotted member, a fulcrum member mounted from said bed plate on a horizontal axis, said member having a slot and said connecting rod being arranged to slide in said slot to rotate the hook drive shaft in the opposite direction and at a non-uniform speed from said first gear.

5. 'Ihe sewing machine as claimed in claim 4 in which the fulcrum slot has converging sides, the connecting rod has a corresponding crosssection and means is provided to hold the fulcrum in various positions relative to the rod, whereby it may be adjusted for initial fit and to compensate for wear.

6. In a sewing machine, in combination, a bed plate, a standard thereon, an arm extending from the standard and supporting a head, a rotary main shaft extending through the standard and arm and into the head, a feed shaft pivoted for oscillation beneath the bed plate at the rear thereof, an arm on said feed shaft adapted for osoillationtherewith about a vertical position, a rotary hook drive shaft rotatably mounted beneath the bed plate near the front thereof, means to drive said last mentioned shaft at a one-toone ratio from the main shaft but at a variable angular speed, a cam on the rotary hook drive shaft, a connecting-rod having one end pivoted to said arm and having an enlarged opposite end provided with an opening loosely receiving said cam, said opening having two opposite sides disposed parallel to the axis of the rod and engaging the cam as followers, a link pivoted to said enlarged end, a movable fulcrum for the opposite end of said link and means to constrain the path of movement of the fulcrum to an`arc bisected by a line through the link pivoted and parallel to the axis of the rod.

7. In a sewing machine as defined in claim 6 in which the fulcrum-constraining means is a second link extending between the fulcrum and a fixed pivot.

8. In a sewing machine, in combination, a bed plate, a standard thereon, an arm extending from the standard and supporting a head, a rotary main shaft extending through the standard and arm and into the head, a feed shaft pivoted for oscillation beneath the bed plate at the rear thereof, an arm on said feed shaft adapted for oscillation therewith about avertical position, a rotary hook drive shaft rotatably mounted beneath the bed plate near the front thereof, means to drive said last mentioned shaft at a one-to-one ratio from the main shaft but at a variable angular speed, a cam on the hook drive shaft, a connecting rod having one end pivoted to said arm and having an enlarged opposite end provided with an opening loosely receiving said cam, said opening having t-we @positie-sides disposed paraiiet te the axis of the rodi andy engaging the cam as followers,-

`a 1ink pivoted to said enlarged end, a movadcilen fulrum for the oppositevendfof' said link, erguidra-nged' tochangev thezphase of oscillation of-"ihe` feedz shaft in respect tothe rotation of the noning-and supporting means for saidi furerum com-Y i riifnn'speed rotary shaft.

piffsin'g a, Secondi link pvoted 0 'saidL fiiltirul-i ai stationary pivot for the opposite end of seid? second link, ai hand lever pivot'ed t@ said Sti-ndard audi extending forwardthrough aslot in thel same, andi a link extending from: said fulcrum to auintermediae rimini,- on seid lever.

9;k A. sewing. machine of the type described chmprising in combination, i :iV uniform' speed mein' shaft arranged'. to ctuate a needle bar, a

miete a. roter-y.k hook,V ai feed shaft meunted fer (facilitation andi arranged`l to: act' combination:

with ssmi non-uniform speed: rotary shaft' boac'- tuate the cloth feeding; device o'ff the sewing ma,-

ehine, means to; osciilsitlieI the feed'Y shaft from wl 2,024,434'

the nonuniform speedi retry: shaft', meansto' BERNARD A` SCHMITT.

REFERENCES CITED The following` references are, of record in the file of thisV patent:

UNITED STATES PATENTS-

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