US2687104A - Eccentric drive for sewing machines - Google Patents

Description

Aug. 24, 1954 A. H. ERIKSSON 2,687,104

ECCENTRIC DRIVE FOR SEWING MACHINES Filed May 9, 1950 2 Sheets-Sheet 1 Wan:

I12 V2f0f ,4 226572 H. EH/rsswz Aug. 24, 1954 A. H. ERIKSSON 2,637,104

ECCENTRIC DRIVE FOR SEWING MACHINES Filed May 9, 1950 2 Sheets-Sheet 2 I Inven'or A ZZan EFLIASJOH A By Z I 1 ZZys. I

Patented Aug 24, 1954 ECCENTRIC DRIVE FOR SEWING MACHINES Allan Herman Eriksson, Huskvarna, Sweden, as-

signor to Husqvarna Vapenfabriks Aktiebolag, Huskvarna, Sweden, a Swedish corporation Application May 9, 1950, Serial No. 160,864

The present invention refers to an arrangement in sewing machines provided with a feeding mechanism, which is adjustable to vary the length of stitch and to reverse the feeding direction.

The main object of the invention is to provide an eccentric driving means which is particularly well suited to the control of a sewing machine having a feeding mechanism of the above mentioned type.

A further object of the invention is to provide an adjustable eccentric driving means which can be easily adjusted as to the magnitude as well as the extent of the eccentricity, and as a result can be utilized in a sewing machine to vary the stitch length and the direction of the feed from forward to back drive andvice versa. A still further object of theinvention is to provide control means for an adjustable eccentric driving mechanism of a simple and compact design.

With these and other objects in. view the invention consists of the mechanism defined in the claims and specified more in detail by way of example in the following description, reference being had to the accompanying drawings in which Fig. 1 is a vertical elevation of a sewing machine, certain parts being illustrated in section along the arm shaft of the machine,

Fig. 2 is a transverse section taken on the broken line II-II in Fig. 1,

Fig. 3 is a part bottom view as indicated by the line IIIIII in Fig. 1 and illustrates a portion of the arm of the sewing machine and a detail,

Fig. 4 is a section on line IV -IV in Fig. 1, and

Fig. 5 is a section on line VV in Fig. 1.

Fig. 6 is an end view of the eccentric proper.

Fig. 7 is a cross section of a detail partly in plan.

The sewing machine illustrated in the drawing comprises the conventional work table I, the hollow standard 2 carried by the table I, the hollow arm 3 forming an integral portion of the standard 2, and the driving mechanism for the stitch form.- ing means and the feeding device for the work, only such parts of the driving mechanism being shown as are necessary for the understanding of the invention. The drive is obtained in the conventional manner through a belt pulley 4 connected to a rotary arm shaft 5 extending longi tudinally in the arm 3.

Secured on the arm shaft 5, through which, inter alia, the needle bar 6 of the sewing machine receives its movement, are two eccentrics 1 and 8, which through the intermediary of eccentric 6 Claims. (Cl. 112210) rods 9 and I 0, levers l I and I2, and rocking shafts M and I5 respectively (Fig. 2) impart to the feeder l5 pertaining to the work feeding mechanism of the sewing machine, the necessary longitudinal and vertical movement. The longitudinal movement must permit of being readily varied to provide for varying stitch lengths and a varying feeding direction, which is facilitated through the eccentric drive in consideration.

According to the invention, the eccentric drive comprises an eccentric 8 having an outer bearing surface 1'! paralleling the shaft 5, the strap it of the eccentric rod Ill being mounted on said bearing surface. The eccentric 8 also has an inner member is, which here takes the form of a cylinder, the envelope surface of which forms a bearing surface carrying the eccentric 8. cylinder is disposed obliquely in such manner that its geometrical axis intersects the axis of the arm shaft 5 at a certain angle. The inner member 19 is displaceable on the arm shaft without being rotatable relatively to the latter, while the eccentric l, which also is non-rotatable relatively to the shaft, takes an unchanged axial position. By axially displacing the member 19 it is possible to move bearing surface I! to alter the eccentric radius of the bearing surface ll relatively to the shaft 5, so that the length of stroke of the eccentric rod I0 is changed with a change of the longitudinal movement of the feeder It for the fabric in consequence thereto.

Instead of displacing the member l9 relatively to the shaft, a displacement of the eccentric is conceivable in connection with a corresponding alteration of the remainder of the arrangement, the substantial feature residing in a mutual axial adjustment of these parts. Also, it is not necessary that the member l9 be constituted by a cylinder; it may just as well consist of an arbitrary suitable parallelopipedon.

The arrangements required for the operation of the adjustment of the member 19 and to prevent turning of said member and the eccentric element 3 relatively to the shaft 5 may be of any suitable kind. However, the details shown in the drawings are particularly well suited in connection with driving means for sewing machines.

The contrivance in consideration is devised so that the surface IT, on which the strap l8 of the eccentric rod in is mounted, is concentric to the shaft 5, when during the axial adjustment of the member l9 said member takes a middle position in which no longitudinal movement of the feeder i6 is obtained. From said middle position, the member [9 may thus be displaced in the one or the other direction, and in the example shown The an equal change of the length of stroke of the eccentric rod will be obtained at an equal displacement of the member I9 in either direction, whereas the position of the eccentric radius is reversed by 180, when member I9 is displaced from a position on one side of the middle position to the other side thereof.

In order to render possible the axial adjustment of the eccentric member I9 in the arrangement shown, said member is connected through a flange coupling, which may entrain the member I9 at an axial adjustment on the shaft but does not prevent its rotation with the latter, to a sleeve which is rotatable and displaceable on the shaft. The flange coupling comprises a flange 2| formed at a tubular portion 22 at member I9 and of a flanged sleeve 23 secured to sleeve 23 by bolts 24, the flanged sleeve 23 and flange 2i engaging one another slidably. Sleeve 23 has a slot 25, with which a plate 27 on a stop screw 23 screwed into the wall of the arm of the sewing machine may be caused to operate. The stop screw and the slot permit rotation of the sleeve 29 through a certain angle on the shaft 5, which angle is reduced, according as the stop screw is screwed in, and is equal to zero, when the plate is entirely within the slot. A spring 28 thrust onto sleeve 20 tends to keep said sleeve with one edge of the slot against the plane bottom surface 29 of the plate 21, so that a certain length of stitch is obtained in the normal sewing or feeding direction from the operator. If the sleeve 20 is turned so that the opposite edge of the slot 25 is caused to touch the bottom surface 29, the same length of stitch is obtained in the opposite feeding direction. Provided on the lower side of the arm of the sewing machine is a pin 30 engaging an obliquely extending slot 3| in the sleeve 20, said sleeve having also an operating lever 32 secured thereon, which projects through an opening 33 on the lower side of the sewing machine arm 3.

The eccentric 8 is non-rotatably arranged on the shaft 5, which feature is ensured for instance by the fact that the eccentric 8 has a ridge i4 engaging a recess 35 in a sleeve 36 secured to the shaft 5 by a screw 31, said sleeve 36 having also the eccentric 1 formed thereon. The inner member I9 is prevented from rotating relatively to the shaft by the fact that a projection 38 thereon engages the recess 35, which is of such an axial extension as to permit the axial displacement of the member I9 at a variation of the eccentricity. By means of the ridge 34 and a ring 39 slidably bearing on the strap I8 of the eccentric rod I 0 the member 8 is mounted so that it can move parallel only with a plane in the transverse direction of the shaft. A retaining ring 40 is secured to eccentric 8 by bolts 4! and contributes to keep said eccentric and strap l8 in correct position relatively to one another. The sleeve 36 has a radial flange 42 transversed by an extension 43 of recess 35, and laterally of said extension the ring 39 is secured to the flange 42 by screws 44. Thus ridge 34, ring 39 and screws 44 couple the eccentric 8 and the sleeve 36 to one another in a manner permitting radial movement of the eccentric relatively to the sleeve but not mutual rotation thereof.

With respect to the mode of operation of the arrangement the following might also be pointed out: As stated, the operating arm is normally retained by the spring 28 in an outer position with one edge of the slot 25 bearing on the plate that it is moved into a middle position, in which the plate 2'! is located opposite the slot 25. Now, if the operating lever 32 is actuated so that the sleeve 20 is caused on account of the pin 30 and the oblique slot 3| to move the eccentric member I3 from its middle position in the direction of the arrow 40 in Fig. 1 as far as is permitted by the stop screw 26 and the slot 25, a maximum eccentricity is obtained for the eccentric drive in the feeding of the work in one direction, for instance in the direction from the operator. Again, if the operating lever 32 is moved in the opposite direction, as far as is permitted by the stop screw, the member I9 is displaced in a direction opposed to that of the arrow 49. The same eccentricity is now obtained, but the radius of the eccentric is reversed with respect to its position by 180, and the feeding direction will be the opposed, that is to say toward the operator. Between the indicated extreme positions the eontrivance may be adjusted by means of the operating lever 32 into arbitrary intermediate positions at a corresponding eccentricity and length of stitch.

The eccentric drive as described brings about a compact structure and is well suited for sewing machines, in particular also sewing machines running at a very high number of revolutions. While the control of the length of stitch becomes simple, an easily effected change of the feeding direction of the fabric is rendered possible at the same time. The eccentric driving means may be mounted on a shaft other than the arm shaf for similar purposes.

What I claim is:

1. In a sewing machine having a rotary shaft in the arm of the standard, an eccentric driving means comprising a member mounted axially displaceably on said shaft, said member having a surface extending at an angle to the axis of the shaft, an eccentric mounted on the shaft and carried slidably by said surface and having an axial bearing surface, an eccentric strap mounted on said bearing surface, an eccentric rod connected with said eccentric strap, means for guiding the eccentric in the radial direction of the shaft, said guide means comprising a sleeve and releasable means to key said sleeve to the shaft in any peripheral position thereon, operating means to displace said axially displaceable member on the shaft relative to the eccentric to displace the eccentric radially and to vary the eccentricity thereby, said eccentric being adjustable during operation, the means for the axial displacement of said member on the shaft comprising the operating sleeve mounted displaceably and rotatably around the shaft and having a slot therein, a plate adjustable to limit the movement of the sleeve for a variable extent by contact in the slot, means to turn said sleeve on the shaft, and means to guide the sleeve to provide only a limited rotary movement but also a limited axial displacement.

2. In a sewing machine having a rotary shaft in the arm of the standard, an eccentric driving means comprising a member mounted axially displaceably on said shaft, said member having a surface extending at an angle to the axis of the shaft, an eccentric mounted on the shaft and carried slidably by said surface and having an axial bearing surface, an eccentric strap mounted on said bearing surface, aneccentric rod connected with said eccentric strap, means 27 of the stop screw 26, but it is assumed here for guiding the eccentric in the radial direction of the shaft, said guide means comprising a sleeve and releasable means to key said sleeve to the shaft in any peripheral position thereon, operating means to displace said axially displaceable member on the shaft relative to the eccen tric to displace the eccentric radially and to vary the eccentricity thereby, said eccentric being adjustable during operation, the means for theaxial displacement of said member on the shaft comprising the operating sleeve mounted displaceably and rotatably on the shaft and having an axial slot and an oblique slot, a stop member engaging said axial slot to a variable extent to variably limit the rotation thereof, and a guide pin in the sewing machine engaging said oblique slot to cause axial displacement of said operating sleeve upon rotation thereof.

3. In a sewing machine having a rotary shaft in the arm of the standard, an eccentric driving means comprising a member mounted axially displaceably on said shaft, said member having a surface extending at an angle to the axis of the shaft, an eccentric mounted on the shaft and carried slidably by said surface and having an axial bearing surface, an eccentric strap mounted on said bearing surface, an eccentric rod connected with said eccentric strap, means for guiding the eccentric in the radial direction of the shaft, said guide means comprising a sleeve and releasable means tokey said sleeve to the shaft in any peripheral position thereon, operating means to displace said axially displaceable member on the shaft relative to the eccentric to displace the eccentric radially and to vary the eccentricity thereby, said eccentric being adjustable during operation, the operating means comprising the operating sleeve mounted around the shaft and having a slot therein, a manually adjustable stop device cooperating with and extending into the slot, and an operating member for displacing the operating sleeve axially on the shaft between two end positions determined by said stop device in the cooperating slot.

4. In a sewing machine having a rotary shaft in the arm of the standard, an eccentric driving means comprising a member mounted axially displaceably on said shaft, said member having a surface extending at an angle to the axis of the shaft, an eccentric mounted on the shaft and carried slidably by said surface and having an axial bearing surface, an eccentric strap mounted on said bearing surface, an eccentric rod connected with said eccentric strap, means for guiding the eccentric in the radial direction of the shaft, said guide means comprising a sleeve and releasable means to key said sleeve to the shaft in any peripheral position thereon, operating means to displace said axially displaceable member on the shaft relative to the eccentric to displace the eccentric radially and to vary the eccentricity thereby, said eccentric being adjustable during operation, the operating means comprising the operating sleeve on the shaft and having a slot therein, a manually adjustable stop device cooperating with and extending into the slot, an operating member for displacing the operating sleeve axially on the shaft between two end positions determined by said stop device in the cooperating slot, and a spring mounted around the sleeve to force said sleeve in one of said end positions.

5. In a sewing machine according to claim 3, in which the operating member is in the form of a manually operable push lever extending in the proximity of the needle operating head of the machine.

6. In a sewing machine having a rotary shaft and a reciprocating work feeding mechanism, an eccentric driving means comprising a member mounted axially displaceably on said shaft, said 1 member having a surface extending at an angle to the axis of the shaft, an eccentric mounted on the shaft and carried slidably by said surface and having an axial bearing surface, means operated by said bearing surface for transmitting motion from said eccentric to said feeding mechanism, means for guiding the eccentric in the radial direction of the shaft, operating means to displace said axially displaceable member on the shaft relative to the eccentric to displace the eccentric radially and to vary the eccentricity thereby, said eccentric being adjustable during operation between diametrically opposite positions corresponding to forward and backward feed, the operating means comprising an operating sleeve mounted around the shaft, an abutment member movable in unison with said sleeve about a middle position corresponding to the eccentricity and the stitch length naught and carrying two abutments corresponding to forward feed and backward feed, a manually adjustable stop member extending into the path of said abutments for alternative cooperation therewith, a spring connected with said abutment member to keep said stop member in engagement with the abutment corresponding to forward feed, and an operating member for displacing the operating sleeve axially on the shaft between two end positions determined by said stop member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 540,843 Richards June 11, 1895 718,988 Dial et al Jan. 27, 1903 2,577,705 Hoffmeister Dec. 4, 1951 FOREIGN PATENTS Number Country Date 242,851 Germany Jan. 22, 1912

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