US2453072A

US2453072A - Adjustable eccentric

Info

Publication number: US2453072A
Application number: US743583A
Authority: US
Inventors: Ralph E Johnson
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1947-04-24
Filing date: 1947-04-24
Publication date: 1948-11-02
Anticipated expiration: 1965-11-02
Also published as: CH260548A; AT169009B; GB659995A; FR954651A; DE864033C

Description

Nov. 2, 1948. R. JOHNSON 2,453,072

ADJUSTABLE ECCENTRIC Filed April 24, 1947 4 Sheets-Sheet 1 INVENTOR. 1 BY 134915 EJ571540? ATTORNEY Nov-{2, 1948. R. E. JOHNSON 2,453,072

' f N 1 x ADJUSTABLE ECCENTRIC. Filed A ril 24, 1947 4 sheets-Ema 2 Y mu" WAQL @M M E Q nun:

INVEN TOR.

Ralph fiJfinw/on Y A T70R11 Nov; 2, 1948. R. E. JOHNSON ADJUSTABLE Emmm 4 SheetsSheet 3 Filed A ril 24, 1947 IN VEN TOR.

Will [55" Arm/2M0" Nov. 2, 1948- R. E. JOHNSC JN ADJUSTABLE; ECCENTRIC 4 Sheets-Sheet 4 Filed April 24, 1947 I N VEN TOR.

E Jfindon A MIA/[SS ATTORNEY Patented Nov. 2, 1948 ADJUSTABLE ECCENTRIC Ralph E. Johnson, Rahway, N. J assignor to The Singer Manufacturing Company, N. J., a corporation of New Jersey Elizabeth,

Application April 24, 1947, Serial No. 743,583

This invention relates tosewing machines, and

more particularly to an adjustable eccentric device adaptable for actuating the feed-dog of a sewing machine in its work-advancing movements which must be variable in magnitude to produce stitches of any length within a given range. Accordingly, the illustrated eccentric device is adjustable to produce eccentric motions of any magnitude within a limited range.

An eccentric motion is, by definition, that motion which is producedby rotating a circular element about an axis whose center is not the geometrical center ofthe circular element. To vary the magnitude of eccentric motions it follows that it is necessary only to vary the radial or linear distance between the center of rotation and the geometrical centerof the circular element. It is possible also to shift this center of rotation, otherwise called the point of eccentricity, angularly, i. e., circumferentially with respect to the geometrical center. This angular displacement of the point of eccentricity in the case of, an eccentric which actuates the feed-dog of a sewing machine in its work-advancing movements, varies the timing of that movement with respect to the other sewing machine elements. More specifically, angular displacement of the point of eccentricity causes the work-advancing motion of the feed-do to begin and to end at diiferent times in the stitch-forming cycle. The radial displacement, on the other hand, varies the linear distance between the center of rotation and the geometrical center, hence varying the magnitude of the work-advancing movement of the feed-dog.

The present invention involves an adjutable eccentric device in which. by means of a unitary adjustment, the point of eccentricity may be shifted both angularly and radially in preestablished ratios, thereby varying simultaneously both the magnitude and timing of the workadvancing movement of the feed-dog.

Also within the purview of this invention is an adjustable eccentric of the illustrated type in which the angular component of displacement of the point of eccentricity is entirelyeliminated.

The structure and operation. of arepresentative form of the invention are described in the following specification referring to the accompanying drawings in which-,

Fig. 1 is a vertical section taken through the lon axis of a sewing machine in which the invention has been incorporated.

Fig. 2 is a bottom viewof the sewing machine. Fig. 3 is a left end view of 'thebed portion of Claims. (01. 74-571 the machine, with the hroat-plate sectioned to expose the feed-dog.

Fig. {l is a vertical section taken substantially along the line fll of Fig. 1. i

Fig. 5 is an enlarged longitudinal sectional viewof an adjustable eccentric device embodying the present invention;

Fig. 6 is a section taken along the line 6-43 of Fig. 5, and shows in full line the eccentric in its maximum eccentricity setting, and insuperirnposed broken lines, the minimum eccentricity setting.

Fig. 7 is an exploded perspective view showing the component parts of the adjustable eccentric unit.

Fig. 8 is an enlarged sectional View of the eccentric taken along the line 88 of Fig. 5.

Figs. 9, 10, 11 and 12 arediagrams showingthe relative angular positions of the adjusting elements of the eccentric for four typical stitchlength settings in the available range.

Referring more specifically to the drawings, a

representative form of the invention is shown incorporated in a sewing machine comprising a bed 20 from one end of which rises a hollow standard 2| which carries an overhanging bracket-arm 22 terminating in a hollow head 23. Rotatably journaled in the bracket arm 22 is a main or arm shaft 2 one end of which. carries a combined belt and ba1ance-whee1 25, the other end of which carries a crank-disk 26. Pivotally secured to the crank-disk 26 is a connectinglink 2! which drives a needle-bar 28 carrying aneyepointed needle 29. Also actuated from the crankdisk 26 by means of a suitable linkage is a thread take-up arm 30, the free end of which is provided with. a thread-eye 3| through which the sewing thread passes in its travel from. the supply to the needle. A spring-depressed presser-bar 32, carrying presser-foot33, is operatively supported in the head 23 in a usual manner. Cooperating with theneedle in the formation of stitches is the loop-taker L, secured upon a shaft 35 and driven by the main shaft 24 through a usual linkage. i 1

A feed-dog 3 cooperates with the presser-foot 33 to advance the material. The feed-dog is mounted on a feed-bar 36 (Fig. 3) which is pivotally supported at one of its ends by an up standing arm 3?, and at its other end by a sub stantially horizontal arm 38. The horizontal arm 38 is secured to a rock-shaft 39 which is mounted in the bed 20 by means of pintle bearings 40 and il. Adjacent the bearing All, the rock-shaft so is provided with an arm :12 which,

cylindrical element 56.

is pinned to the lower end of a pitman link 43, the upper end of which embraces a fixed eccentric 44 secured to the rotary arm shaft 24 by a set screw 45 (Fig. During rotation of the shaft 24, the eccentric 44 will actuate the pitman 43, thereby oscillating the rock-shaft 39 which, through the arm 38, will cause the feed-bar 36 to rise and-fall once for each rotation of the shaft 24. This movement of the feed-bar is commonly designated as feed' lift motion.

Work advancing motion is imparted to the feed-bar 36 by means of the upright arm 37 which is secured to a rock-shaft 46 mounted in the bed 26 by means of pintle bearings. 41. Adjacent the pintle bearings 41, the rock-shaft 46 is provided 1 with an arm 48 which is pivotally connected to the lower end of a pitman link 49, the upper end of which embraces an outer cylindrical element 59 of an adjustable eccentric device E. Rotation of the shaft 24 causes the eccentric device E to actuate the pitman 49 which, in :turn, oscillates the rock-shaft 46 which, through the upright arm 31, causes the feed-bar v36 to reciprocatein a substantially horizontal plane. Operating in timed relation with the feed-lift motion, this horizontal movement causes the feed-dog 34 to trace a substantially elliptical path. It is apparent that varying the eccentricity of the eccentric device E will vary the magnitude of the horizontal movement of the feed-dog 34, thereby changing the stitch length.

The adjustable eccentric device E comprises a driving disk or collar 56 rigidly secured to the rotary arm shaft 24 by a set screw 5|. A channel 52 in the driving disk 50 slidably receives a tongue portion 53 of an elliptical connecting link 54 which accommodates the rotary armshaft 2 4 by means of an elongated slot 55 which limits the sliding movement of the elliptical connecting link 54 in the channel 52. A cylindrical element 56 is rotatably mounted upon the shaft 24 by means of an eccentrically disposed aperture 51. An oil groove 58 is provided in the surface of the cylinder 56 to conduct lubricant to the working elements of the eccentric. outer cylindrical element 59 is provided with an eccentrically disposed aperture 66 by means of which it is rotatably mounted upon the inner A longitudinal slot 6| in the aperture 60 of the cylinder 59 provides an assembling clearance for a pivot-pin 62 which is carried by the cylinder 56 and which protrudes beyond the periphery thereof. In its assembled position a portion of the pin 62 overhangs the face .63 of the cylinder 59. A slide-block 64 is provided with a hole 65 by means of which it is mounted on the pin 52. In their assembled positions, the pin 62, the slide-block 64 and a driving pin 66, which is made integrally with the cylinder 59, all lie in the plane of the elliptical connecting link 54. This member is provided with slots 61 and 68 which receive, respectively, the driving pin 66 and the slide-block 64.

The'

made fast to the shaft 24 by the set screw 45. A spring 19 (Fig. 8) securedto the flange 69 by a screw 19', biases the slidable locking-plate H so that its teeth 13 engage the teeth 14 of the disk i5. Two arcuate ribs 80, projecting from one face of the flange 69, serve as bearings to position the toothed -disk 75.. r-Fona'rmore complete disclosure of a similar construction including the flange 69, the slidable locking-plate H, and the toothed disk l5, reference may be had to the U. S, patent of R. Kaier, No. 2,161,579.

To adjust the eccentric device: With the sewqing machine stopped, a spring retracted plunger- :pin: 81;.mo1intedrin the bracket-arm 22, is manuallydepressed, and the shaft 24 rotated by hand by means of thebalance-wheel until the plunger-pin 6| engages a slot 82 in one end of the slidable locking-plate 7!. Additional pressure on the plunger-pin causes the locking-plate H to slide against the action of the spring! 51.9 1(Fig-i8), thereby disengaging. the locking-platea teeth 13 from the disk teeth 14 which frees the. inner Integral with the cylindrical element 56 is .a

flange portion 69, formed with a channel 10 which receives a slidable locking-plate H. This locking-plate is formed with a struck out portion 12 which is provided with teeth 13 adapted to engage the peripheral teeth M of a disk 15 mounted The pin H is anchored inJthe cylindrical element 56 from the shaft 24. When engaged by theplunger-pin 8|, the locking-plate in is thereby locked to the frame of the sew ng machine. Consequently, the inner cylindrical element 56 :is effectively locked to the frame of the machine since the locking-plate ll iscrecessed in the channel 16 of the flange portion 69 ofthe inner: cylindrical element. 'By maintaining the plunger-pin '6! .in its depressed position, the shaft '24 may 'be rotated a limited amount relatively to the innerccylindrical element 56.

Relative rotation is also set up :between the shaft 24 and the outer cylindrical element 59 by means of a motion-modifying driving connection therebetween. 'The' adjusting rotation of the shaft 24 is imparted directly to the ellipticalconnecting link 54 by means of the dri ving disk 56 which a'ccommodates'the elliptical member in the channel 52. This rotation of the elliptical member is, in turn,'transmitted to the outer cylindrical element 59 through the driving pin 66. Inaddition to its angular rotation, the elliptical connecting link '54 slides laterally in the channel 52. This sliding movement imparts additional rotation to the cylindrical element 59 through the driving pin 66. The sliding movement is caused by the fact that the elliptical connecting'link 54 is constrained by the slide-block 64 mounted on the pin 62 which is integral with the stationary, inner cylinder element 56. Because the'pin'62 is secured against rotation, the elliptical member 54, when rotated by the driving-disk 5 6,is forced to pivot about'the pin 62. In order to pivot about the pin 62, which isspaced from the center of rotation of the shaft 24, the elliptical member must necessarily shift laterally inthe channel 52. Thus the outer cylindrical element 59 is caused to rotate byan amount equal to the angular rotation of the shaft 25 plus that rotation *which-iscaused by the sliding movement of the {elliptical connecting link 54.

It is to be understood from vthe foregoing description that during adjustment of the eccentric device, relative angular motions are set up between: '(a) the actuating shaft 24 andthe inner cylindrical element 56,, b) the inner cylindrical element 56 and the outer cylindrical element :59, and .(c) the, outer cylindrical element 59' and the shaft24. Asa convenient means for indicating the amount ofadjustment of the eccentric, suitable calibrations are provided on. the inner face 83 of the balance wheel 25 to cooperate with an indicating mark 84 on the frame ofthe sewing 1 machine (Fig- 1). t l i The mannersin which the component elements of the eccentric unitlcooperate to establish the eccentricity is shown by Figs. 9-12. Fig; 9 shows the relative angular positions of the elements at zero eccentricity. This setting corresponds to a stitch length of zero in which no work advancing motion is imparted to the feed-dog. Figs. 10 and 11 show the relative positions of the elements for providing approximately twenty-two and fourteen stitches per inch, respectively. Fig. 12 showsthe relative positions for the maximum eccentricity attainable by the illustrated device, which corresponds to approximately five and onehalf stitches per inch in the illustrated machine.

Referring to the diagrams, it will be noted that letters are used to identify geometrical points, as distinguished from numerals which identify mechanical elements. The letters is the geometrical center of the shaft 24, i is the geometrical center of the inner cylindrical element 56, and 0 the geometrical centerof the outer cylindrical element The center of rotation of the shaft 24 is, of course, coincident with its geometrical center 5. The center of adjusting rotation of the inner cylindrical element 56 (because it isrotatably mounted on the shaft 24) is the geometrical center s of that shaft. It follows that the outer cylindrical element 59 (because it is rotatably mounted upon the inner cylindrical element 56) has for its center of rotation the geometrical center i of the inner cylindrical element. It should be noted that the centers of rotation z and 0 have significance only during adjustmcntof the eccentric device, since thedriving operation of the eccentric is performed with the three

elements

24, 56 and 59 locked together to form a unitary structure whose center of rotation is the center 3 of the actuating shaft 24.

The eccentricity of a circular element is by definition the linear distance between its center of rotation and its geometrical center. Thus the distance 8-2, is thejeccentricity of the inner cylindrical element 56, with respect to the shaft 24. The distance i-o is the eccentricity of the outer cylindrical element 59 with respect to the inner cylindrical element 56. The vectorial sum of these distances is s,fo, which represents the resultant or total eccentricity of the adjustable eccentric unit. When the eccentricities s-i and i-o (which are equal in magnitude in this unit) are opposed as in Fig. 9, the resultant eccentricity is zero and the center of rotation s and the geometrical center 0 are in coincidence. In Fig. 12, which is the maximum adjustment for the illustrated unit, the eccentricities s-z and z-o add vectorially to produce the resultant s -o.

If the line joining the center of rotation and the geometrical center of either cylindrical element be extended, the intersection of the line with the periphery of the element will be the point farthest from the center of rotation. This point is termed the high-point. In Figs. 9- 12, h represents the high-point of the outer cylindrical element 59, hi the high-point of the inner cylindrical element 56, and H the resultant highpoint of the two combined eccentricities, found by extending the resultant line so.

In Fig. 9 the distance s-o is zero, therefor no high-point H exists. In Fig. 10 the shaft 24 has been rotated counterclockwise twenty-:two degrees. This amount of shaftjrotation, because the latter to rotate in the same direction for thirty-eight degrees. The high-point H, which began its generation at the point b, has been rotated sixteen degrees in the direction of rotation of the shaft. The relative motion, or net angular displacement, between the shaft 24 and the high-point H is; therefore, six degrees. This angular displacementrepresents a change in the timing of the work-advancing component of the feed-dog motion for the reason that all of the sewing machine mechanism, except that which i is concerned with the work-advancing movement of the feed-dog, has been displaced inproportion to the twenty-two degrees of rotation of the arm shaft 24, while the feed-dog has been displaced inproportion to the sixteen degrees of rotation of the high point H.

of the action of the previously described motionmodifying driving connection between the shaft In Fig. 11 the'shaft 24 has been rotated co nterclockwise thirty-two degrees from the position illustrated in Fig. 9, which through the motionmodifying means has caused forty-eight degrees rotation of the outer cylindrical element 59. The p high-point H hasbeen rotated twenty-threadegrees, leaving a net angular displacement of nine degrees between the point H and the shaft 24.

In Fig. 12 the shaft has been rotated counterclockwise ninety-three degrees, thereby causing one hundred and fifty degrees rotation of the outer element 59, the result of which is seventyfive degrees of rotation of the high-point H. The

difference between the angular rotation of the shaft 24 and the high-point His eighteen degrees which is the maximum relative displacement provided by theillustrated eccentric device.

The angular rotations of each of the three adjusting elements including the shaft 24, the inner cylindrical element, 56, and the outer cylindrical element. 59, are shown in the diagrams to :be

measured with respect to a fixed point, such as i the frame of the sewing machine. It should be noted, however, that adjustment of the eccentric device dependsupon the relative rotation of each of the three elements with respect to the other two; Thus it is possible to adjust this eccentric device With identical results by holding stationary the shaft 24 and rotatingthe inner cylindrical element 56 by means of its flange portion .69.. The absolute angular rotations, i. e. rotations with respectto a fixed point, will be changed, but the relativerotations between the three elements as well as the displacemen'tof the high-point H with respect to the shaft 24 will be unchanged. Likewise similar adjustin results could be obtained by holdingstationary the outer cylindricalelement 59 and setting up relative adjusting rotation between the shaft24 and the inner cylindricalele ment 56.. This Wouldinvolve the simple structural modification. of interchanging the distance between thepin 65 and the center of the shaft 24 with the distance between the pin 52 and the cylindrical. element. 59 will result in limited relative movement between the outer cylindrical ele ment 59 andthe-shaft 24. This motion is caused bythe'fixe'deccentricity of theinner cylindrical aircrew element .56 with respect toithev'shaft:andicannot beeliminated. The effectrisrillustratedibysEignll of the U. S. patent of A. Grieb, No. 1,605,937. The instant invention, however,isdistinguishable in that it concerns relative movement between the shaft 26- and the outer cylindrical element 59 in addition to that causediby'the fixedeccentricity of the inner cylindrical element '56 .with"respect to the shaft.

justingmechanism for said eccentric; unit comprising motion-modifying driving linkage operatively associatedwith said cylindrical elements.

2. 'In a sewing machine having a frame, a shaft rotatably mounted in said frame,.and mechanism adapted to beactuated by said shaft; an eccentric unit mounted upon said shaft comprising an inner cylindrical element eccentricall apertured and thereby rotatably mounted upon the said. shaft, an outer cylindrical element eccentrically apertured and rotatably mounted thereby upon the said inner cylindrical element, and unitary means for adjusting said eccentric unit, comprising motion-modifying driving connections for effecting relative angular rotation between said shaft, inne cylindrical element, and outer cylindrical element in which the outer cylindrical element is rotated relatively to the inner cylindrical element, the inner cylindrical element is rotatedrelatively to the actuating shaft, and the shaft is rotated relativel to the outer cylindrical element by an r amount exceeding that which is caused by the fixed eccentricity of the said inner cylindrical element with respect to the actuatingshaft.

3. In a sewing machine having a frame, an actuating shaft rotatably mounted in said frame, and mechanism adapted to be actuated by said shaft; an adjustable eccentric unit mounted on said actuating shaft and comprising, a rotatable inner cylindrical element eccentricallyv apertured to accommodate said actuating shaft, a rotatable outer cylindrical element eccentric'ally apertured to accommodate said inner cylindrical element, and unitary adjusting means comprising motionmodifying drivin connections for effecting relative angular rotation between the said shaft, inner cylindrical element, and outer cylindrical element, in which the shaft is rotated an absolute angular distance exceeding that of...the inner cylindrical element, and the outer cylindrical element is rotated an absolute angular. distanceexceeding that of the shaft plus that rotation of the outer cylindrical element which is caused by, the fixed eccentricity of the. inner cylindrical element with respect to the shaft.

4. In a sewing machine having a frame; a shaft rotatably mounted in said frame, and mechanism adapted to be actuated by .said shaft; an adjustable eccentric unit mounted upon said shaft, comprising an inner cylindrical element eccentrically apertured to accommodate the said shaft, ,an outer cylindrical element eccentrically apertured to accommodate said innerv cylindrical element, and adjusting mechanism for said eccentric unit comprising a motion-modifying driving connection between the said shaft and theoutercylin- 8 meals-element 101": establishing rotatiozr dhereba. tween by an amount differing .fronrithatzcaused byztheifixed eccentricity of the :innerrcyiindiical element with respect :to: thewshaft.

.lnasewin imachine having a, frame, ashaft rotatably; mounted in .'-said :frame; and mechanism adaptedito-be actuated l y-said shaft; ran adjustable eccentric unit -c om prising-an innericylindri'cal element eccentrically 'aperturecl and rotatably mounted thereby-31min said. shaftgan eouter -;cylindrical. element eocentrieally :apertured and rotatably mounted thereby-upon the saidinner cylindr-i'cal element, :and unitaryadlusting mechanism, for :said eccentric. comprising -.a motionmodifying driving connection between the-said shaft and the said inner cylindrical; element.

.6 In .a sewing machine havingia frame,;.;an actuating shaft-rotatably :mounted in said frame, and mechanism adapted to betactuated by. said Shaft}. an eccentric unit mounted upon saidshaft and comprisingzan inner cylindrical element -60? centrically apertured .and thereby. rotatably mounted upon said shaft, an outer cylindrical element .eccentrically apertured and rotatably mounted thereby upon the said inner cylindrical element, andv unitary adjusting, means for said eccentric unit comprising; a motion-modifying driving connection betweensaid inner and outer cylindrical elements.

7. ..In asewingmachine having aframe, ashaft rotatablymountedin said frame, and mechanism adapted ,tobe actuated by said shaft; an adjustable eccentric unit mounted. uponsaiol shaft, said. eccentric .unit comprising aninner cylindrical elei .menteccentrically apertured to accommodate .the

said, shaft, an outer cylindrical element ieccentrically apertured to accommodate said inner cylindrical .element, releasable means for locking .oneof said cylindrical elements to said frame, and a unitaryrmeans for adjusting saideccentric unit comprising a motion-modifying driving connection between the other of said cylindrical elements and the, said shaft.

' 8. In asewing machine having a frame, a shaft rotatably mounted in said frame, and mechanism adapted to be actuated by said shaft; an adjustableeccentric unit comprising an inner cylindrical element eccentrically. apertured and rotatably mounted thereby upon said shaft, an outer cylindrical element eccentrically aperturedand rotatably. mounted thereby upon the ,said inner'cylindrical element, a collar mounted upon said shaft, a pin eccentricallydisposed with respect to the said shaft, a connecting, link slidably mounted in said collar and pivotally constrained by said pin, and an operative driving connection between said link and said outer cylindrical element.

' 9. In a sewing machine having. aframe, a shaft rotatably mounted in saidjframe, and mechanism adapted tojhe actuatedby said shaft; an adjustable eccentric unit comprising an inner cylindrical element eccentrically apertured parallel to its center-line and rotatably, mounted thereby upon the..sa id..shaft,,an outer cylindrical. element eccentrically apertured parallel to its center-line androtatably mounted thereby upon said inner cylindrical element, a collar mounted upon said shaft, a pin eccentricallydisposed with respectto the center of sa'idshaft, aconnecting link slid ably mounted in said. collar and pivotally constrained by, saidpin, ,and an operative driving connection between said link and said inner cylindrical element.

ML- Ina sewing machine having a frame, a shaft rotatably mounted in said frame, and. mechanism adapted to be operated by said shaft; an adjust- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Number Date 1,605,937 Grieb Nov. 9, 1926 1,956,447 Laessker Apr. 24, 1934 10 2,161,579 Kaier June 6, 1939 Zonis Jan. 20, 1942