TWI689641B - Stitch length-adjusting device for a sewing machine and sewing machine with such a stitch length-adjusting device - Google Patents

Abstract

A stitch length-adjusting device (25) for a sewing machine has a stop unit (26) for specifying stops for a lever body (27). The latter can be reset by pivoting about an adjusting axis (28) between a forward stitch stop position and a backward stitch stop position. The adjusting device (25) also has a stitch regulator gear (49), which is connected on the one hand to the lever body (27) and on the other hand to a transporter drive shaft. An assembly frame (52) of the stitch regulator gear (49) is connected in a rotationally secure manner to the lever body (27). This results in a stitch length-adjusting device with improved stability of a stitch length specification.

Description

Stitch length adjusting device for sewing machine and sewing machine with such stitch length adjusting device Citation of related applications

This application incorporates by reference the content of the German patent application DE 10 2015 207 998.8.

Field of invention

The invention relates to a stitch length adjusting device for sewing machines. The invention also relates to a sewing machine including such a stitch length adjusting device.

Background of the invention

From DE 100 13 414 C1, a stitch length adjusting device for sewing machines is known.

Summary of the invention

An object of the present invention is to improve the stability of a stitch length specification (specified value, predetermined value) by a stitch length adjustment device.

According to the present invention, the object is achieved by a stitch length adjusting device for a sewing machine, -The stitch length adjusting device has a stop (limit) unit for specifying (defining, pre-specifying) a stop for the lever body, which can be turned by pivoting about the adjustment axis in the following Adjustment between positions: - Forward stitch stop position, the forward stitch stop position is used to specify the conveying movement of the sewing workpiece conveyor in the sewing workpiece conveying direction; - Back stitch position, the backward thread The stitch stop position is used to specify the conveying movement of the sewing workpiece conveyor in the direction opposite to the conveying direction of the sewing workpiece,-the stitch length adjusting device includes a stitch regulator gear, which is on the one hand Connected to the lever body and on the other hand to the conveyor drive shaft;-wherein the assembly frame of the stitch regulator gear is connected to the lever body in a rotationally fixed (non-rotatable) manner.

By specifying the conveying motion of the conveyor in the stitch length adjusting device, the corresponding stitch length specifications can be defined. According to the invention, it has been recognized that the assembly frame of the stitch regulator gear and the lever body, which can be adjusted between stop positions for conveying movement specifications, are rotationally fixed or torque-proof connections That is, the common rotation axis of the assembly frame and the lever body increases the stability of the stitch length adjustment device, and accordingly makes the accuracy and stability of the stitch length specification greater. Unnecessary relative movement between the stitch regulator gear and the lever body is avoided. It is also possible to make the stitch regulator gear assembly frame and the lever body have an integral design.

The embodiment of the stop unit as an adjustment slider results in The stitch is coupled with a highly precise form fit of the specification of the stop position of the backward stitch. In this embodiment, the stop unit is designed as an adjustment slider for the lever body, which can be passed by Pivot about the adjustment axis to pivot between the following positions: - Forward stitch slider position, the forward stitch slider position forms the forward stitch stop position for specifying the sewing workpiece transport The movement of the sewing machine in the conveying direction of the sewing workpiece; - the position of the backward stitch slider, which forms the stop position of the backward stitch, and is used to designate the sewing workpiece conveyor in The conveying movement in the direction opposite to the conveying direction of the sewing workpiece.

An adjustment shaft extending along the adjustment axis is a particularly suitable member for connecting the lever body to the assembly frame in a rotationally fixed or torque-proof manner, the lever body and the assembly frame Connected to the adjustment shaft in a rotationally fixed manner.

A setting driver operatively connected to the lever body to set the lever body enables automatic adjustment between forward stitches and backward stitches. The setting drive can be designed as a pneumatic cylinder.

The forward adjustment device includes a first forward stitch setting device and a second forward stitch setting device, the first forward stitch setting device is used to designate the position by displacing at least one stopper in the stopper unit. A large forward stitch length in the sewing workpiece conveying direction, the second forward stitch setting device is used to designate in the sewing workpiece conveying direction by displacing at least one stop in the stop unit The second smaller forward stitch length. The forward adjustment device increases the comfort level when operating the sewing machine.

The short stitch adjusting device is used to specify the short stitch length in the conveying direction of the sewing workpiece by displacing the short stitch stop body for the short stitch lever body connected to the stitch regulator gear, the short stitch length It is shorter than the forward stitch length. The short stitch adjustment device allows additionally specifying the short stitch length. Such short stitches can be used, for example, for the line segment at the end of the seam to be stitched.

The assembly frame of the stitch regulator gear is connected to the short stitch lever body in a rotationally fixed manner, which ensures a suitable height of reliability of the short stitch adjustment device.

The pre-defined position where the stop position of the short-stitch lever body on the short-stitch stop body can be specified by displacing the short-stitch stop body around the stop body axis makes it easy to adjust the short line Trace length.

A short stitch setting device operatively connected to the short stitch lever body to set the short stitch lever body enables automatic setting of the sewing machine to short stitch operation. The short stitch setting drive can be designed as a pneumatic cylinder.

In the designation of the stop position, the short-stitch lever body on the short-stitch stop body is performed by specifying the stop of the driver body of the short-stitch setting driver on the short-stitch stop body The designation of a stop position, which prevents the short-stitch lever body from being directly stopped on the short-stitch body, thereby reducing wear of the short-stitch lever body.

The calibration device for adjusting the length ratio between the forward stitch length and the backward stitch length makes it possible to finely adjust the length of the forward stitch on the one hand, and the other The length of the backward stitch can be finely adjusted. It is thus ensured for the backward stitch that the needle pierces accurately at the same position in the sewing workpiece as the position for the forward stitch. The calibration device can be designed by the eccentric adjustment of the stop unit in order to specify the forward stitch and backward stitch stop positions of the lever body, and in particular by the eccentric adjustment of the adjustment slider.

The advantages of the sewing machine having the stitch length adjusting device according to the present invention correspond to those advantages that have been explained above with reference to the stitch length adjusting device according to the present invention.

1‧‧‧Sewing machine

2‧‧‧ substrate

2a‧‧‧Board case

3‧‧‧pillar

3a‧‧‧Column housing

4‧‧‧arm

4a‧‧‧arm housing

5‧‧‧Sewing machine housing

6‧‧‧Head

6a‧‧‧Head shell

7‧‧‧Needle bar

8‧‧‧clamp

9‧‧‧Support plane

10‧‧‧support plate

11‧‧‧ stitch board

12‧‧‧Lower sewing workpiece conveyor

13‧‧‧Main housing parts

14‧‧‧Housing cover

15‧‧‧arm shaft

16‧‧‧arm shaft drive motor

17‧‧‧Toothed belt

18‧‧‧Drive gear

19‧‧‧ drive shaft

20‧‧‧arm shaft gear

21‧‧‧Lower shaft gear

22‧‧‧Tension pulley

23‧‧‧Handwheel

24‧‧‧lower axis

24a‧‧‧Needle conveying shaft

24b‧‧‧Needle bar slider

25‧‧‧ Stitch length adjusting device

26‧‧‧stop unit, adjustment slider

27‧‧‧Lever body

28‧‧‧Adjust the axis

29‧‧‧bolt

30‧‧‧ Forward stitch bending area

31‧‧‧backward curved area

32、38‧‧‧Set driver

33, 39, 55

34、40‧‧‧Curved surface

35‧‧‧First forward adjustment device

36、42‧‧‧Spherical free end

37、41‧‧‧Lever surface

43‧‧‧Second forward adjustment device

44‧‧‧ Calibration axis

45‧‧‧ Calibration device

46‧‧‧Eccentric parts

47‧‧‧Calibration adjustment screw

49‧‧‧stitch regulator gear

50‧‧‧ Transmission lever

51‧‧‧Conveying drive shaft

52‧‧‧Assembly frame

53‧‧‧Adjustment shaft

53a‧‧‧Eccentric lever

54‧‧‧Short stitch adjustment device

56‧‧‧Short stitch setting driver

58‧‧‧Short stitch lever body

59‧‧‧Short stitch stop body

60‧‧‧Outer belt

61‧‧‧Curved Opposite Surface

62‧‧‧Pivot axis

63‧‧‧Assembly screws

64‧‧‧rotating threaded pin

Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a rear view of the sewing machine in which external sewing machine parts have been partially omitted; FIG. 2 shows a front view of the sewing machine according to FIG. 1, that is, a view from the operator's side, in which the closing sewing machine has been omitted The operator side of the housing and the housing cover of the inner and outer sewing machine parts; FIG. 3 shows a perspective view of the sewing machine according to FIG. 2; FIG. 4 shows the driving parts of the sewing machine for driving the stitch forming tool and the upper and Lower sewing workpiece conveyor; FIG. 5 shows a cross-sectional view of the components of the stitch length adjusting device housed in the upright of the sewing machine housing according to the line VV of FIG. 1, where these components of the stitch length adjusting device are shown Is located at the position of "large stitch length for forward stitching"; FIG. 6 shows a view similar to FIG. 5 of the components of the adjustment device located at the position of "backward stitching"; 7 shows a detailed view of the sewing machine in the vicinity of the two adjusting wheels for setting the forward stitch length on the one hand and the backward stitch length on the other hand from the operator side; FIG. 8 shows Sectional view of line VIII-VIII; FIG. 9 shows a partial sectional view of the sewing machine near the short stitch setting driver from the viewing direction IX of FIG. 1, the short stitch setting driver being shown as being located at the "maximum adjustable forward stitch length" FIG. 10 shows the short stitch setting driver at the “short stitch” position; and FIG. 11 shows a cross-sectional view along the line XI-XI of FIG. 10.

detailed description

The sewing machine shown in FIGS. 1 and 3-in which the inner and outer parts are partially omitted-has a base plate 2, a post 3 and an upper arm 4 arranged upright from the base plate 2. The base plate 2, the pillar 3, and the arm 4 are parts of the sewing machine housing 5, and the sewing machine housing 5 has a base board housing portion 2a, a pillar housing portion 3a, and an arm housing portion 4a. The arm 4 terminates in a head 6 having a head housing portion 6a.

In the vicinity of the head housing portion 6a, the sewing machine 1 has a stitch forming tool, that is, a needle bar 7 in which an organic needle (not shown) is fixed, and a thread clamp 8 schematically shown by a broken line in FIG. The thread clamp 8 is arranged below the support plane 9 defined by the support plate 10. A part of the support plate 10 is a stitch plate 11 (see FIG. 4). The stitch plate 11 has a central through opening for sewing the workpiece conveyor 12 downward. The lower sewing workpiece conveyor 12 has a stitch hole through which the needle passes.

The sewing machine housing 5 has a cast main housing part 13 which has zero The piece 13 is designed to be open on the operating side, as shown in the views according to FIGS. 2 and 3. The main housing part 13 is designed as an integral piece, and includes a pillar housing portion 3a, an arm housing portion 4a, and a head housing portion 6a. The main housing part 13 is configured so that it can be cast in a coreless form without undercuts.

In order to close the operator's side of the sewing machine housing 5, a housing cover 14 is used, which is shown in a cross-sectional view in cut-out form in FIG. 6. The housing cover 14 can be designed as a single piece, or alternatively can be designed as multiple parts. The housing cover 14 is made of plastic.

The stitch forming tools-namely the needle bar 7 and the thread clamp 8-are driven by the arm shaft 15. The arm shaft drive motor 16 (see FIGS. 3 and 4) is operatively connected to the arm shaft 15 through a toothed belt 17.

The arm shaft drive motor 16 is attached to the arm case portion 4a on the case side away from the operator side. The arm shaft drive motor 16 is installed in the recess of the sewing machine housing 5. The axial extension of the arm shaft drive motor 16 corresponds to the width of the column housing portion 3a.

The drive gear 18 meshes with a toothed belt 17 (see FIG. 9 ), which is connected to the drive shaft 19 of the arm shaft drive motor 16 in a rotationally fixed manner. The arm shaft drive motor 16 is firmly attached to the housing in the vicinity of the arm housing portion 4a.

The drive shaft 19 of the arm shaft drive motor 16 extends parallel to the arm shaft 15. The distance between the drive shaft 19 and the support plane 9 is greater than the arm shaft 15.

The driving device, that is, the toothed belt 17 is arranged on the side of the arm shaft driving motor 16 opposite to the head housing portion 6a. The drive motor 16 does not represent the extension of the arm shaft 15. The drive shaft 19 and the arm shaft 15 are not aligned.

The arm shaft gear 20 and the lower shaft gear 21 mesh with the toothed belt 17. The toothed belt 17 travels between the drive gear 18 and the arm shaft gear 20 on the tension pulley 22. The arm shaft gear 20 is arranged between the arm housing portion 4 a and the hand wheel 23 of the sewing machine 1, which is connected to the arm shaft 15 in a rotationally fixed manner. The lower shaft gear 21 is connected to the lower shaft 24 in a rotationally fixed manner, and the thread clamp 8 and other components are driven through the lower shaft 24.

Parallel to the arm shaft 15 is the needle conveying shaft 24a, through which the needle shaft slider 24b oscillates, and the oscillating motion is derived from the rotation of the arm shaft. Thus, in a known manner, the needle conveyance is carried out by being conveyed on the sewing workpiece by the sewing machine 1.

The needle bar slider 24b and the lower conveyor 12 enable the sewing machine 1 to carry the sewing article up and down.

The sewing machine 1 has a stitch length adjusting device 25, and the components of the stitch length adjusting device 25 are specifically shown in FIGS. 4 to 10. With the stitch length adjusting device 25, a large stitch length can be specified for the forward conveyance of the sewing workpiece in the sewing workpiece conveying direction x (see FIG. 3), and can be in the opposite direction (-x) of the sewing workpiece conveying direction x Sewing workpiece conveyance specifies the backward stitch length, and a short stitch length can be specified for the line segment in the sewing workpiece conveying direction x. In addition, the length ratio between the forward stitch length and the backward stitch length can be calibrated.

The stitch length adjusting device 25 has a stop unit 26 for specifying a stop for the lever body 27. The lever body 27 can be readjusted around the adjustment axis 28. The stop unit 26 is designed as an adjustment slider for the bolt 29 of the lever body 27, and is also referred to as a jaw.

The forward stitch stop position of the sewing workpiece conveyor 12 shown in FIG. 5 for specifying the conveying movement of the sewing workpiece conveyor 12 in the sewing workpiece conveying direction x is the same as that shown in FIG. 6 for specifying the sewing workpiece conveyor 12 during sewing. The lever body 27 is adjusted between the backward stitch stop positions of the conveyance movement in the opposite direction (-x) of the workpiece conveyance direction x. The forward stitch stop position is the forward stitch slider position where the bolt 29 abuts the forward stitch bending area 30 of the adjustment slider 26. The backward stitch stop position is designed as a backward stitch slider position at which the bolt 29 abuts on the backward stitch bending area 31 of the adjustment slider 26.

In order to adjust the lever body 27 between the forward stitch stop position and the backward stitch stop position, a setting drive 32 is used, which is designed as a pneumatic cylinder with a piston 33. The piston 33 is fully retracted in the forward stitch stop position according to FIG. 5, and in the backward stitch stop position according to FIG. 6 is extended to such an extent that the lever body 27 in FIGS. 5 and 6 surrounds the adjustment axis 28 Pivot counterclockwise to the backward stitch stop position. The piston 33 thus rests on the curved surface 34 of the lever body 27.

5 and 6 show the stop unit 26, that is, the adjustment slider, at the "large stitch length" position. In order to specify the large forward stitch length at the position according to FIG. 5 and the corresponding large backward stitch length at the position in FIG. 6, the first forward adjustment device 35 is used. The first forward adjustment device 35 is formed by an adjustment wheel that cooperates with an axially displaceable screw mandrel.

The spherical free end 36 of the threaded mandrel abuts on the lever surface 37 of the stop unit 26 to specify its "large stitch length" position. In this "large stitch length" position, the stop unit 26 is pretensioned by a prestressed spring. Adjust by setting The wheel 35 can finely adjust the position, and thus can define a large stitch length.

By additionally setting the driver 38, the stop unit 26 can be reset between the "large stitch length" position shown in FIGS. 5 and 6 and the "small stitch length" position not shown in the figure. In the "small stitch length" position, the piston 39 of the setting driver 38, which is also designed as a pneumatic cylinder, extends and pushes against the curved surface 40 of the stop unit 26 until its additional lever surface 41 abuts in the second direction On the spherical free end 42 of the threaded mandrel of the front adjustment device 43. Like the first forward adjustment device 35, the second forward adjustment device 43 is also designed as an adjustment wheel.

When adjusting between the "large stitch length" position and the "small stitch length" position, the stop unit 26 pivots about the calibration axis 44 mounted eccentrically. The calibration shaft 44 is part of a calibration device for adjusting the length ratio between the forward stitch length and the backward stitch length. The eccentric 46 is mounted on the calibration shaft 44 and fixed by a calibration adjustment screw 47 (see FIG. 8). By releasing the calibration adjustment screw 47, the eccentric 46 can rotate around the calibration axis 44. The calibration adjustment screw 47 is accessible from the outside via an elongated hole 48 on the user's side. The z-direction extension of the elongated hole 48 defines the calibration adjustment area of the eccentric 46.

In an alternative embodiment of the calibration device 45 that is not shown, the eccentric 46 is releasably connected to the stop unit or the adjustment slider 26 via a calibration adjustment screw. In this modification, the stitch length is determined by adjusting the joint rotation of the slider 26 and the eccentric 46 around the calibration axis 44. The calibration adjustment screw in this variation is accessible from the outside via a curved elongated hole that specifies the allowable calibration adjustment range of the eccentric 46.

Part of the stitch length adjusting device 25 is designed flat in a known manner The stitch regulator gear 49 of the tab gear. The stitch regulator gear 49 is connected to the lever body 27 on the one hand, and to the conveying drive shaft 51 via the transmission lever 50 and the lever joint on the other hand, which is also indicated as the stitch regulator shaft. The stitch regulator shaft 51 is designed as a pivot shaft. The pivot angle of the stitch adjuster shaft 51 about its longitudinal axis is a measure of the conveying movement of the lower sewing workpiece conveyor 12 in the sewing workpiece conveying direction or in the direction opposite to the sewing workpiece conveying direction. By further deflection, the stitch adjuster shaft 51 is connected to the lower sewing workpiece conveyor 12.

The assembly frame 52 of the stitch regulator gear 49 is connected to the lever body 27 in a rotationally fixed or torque-preventing manner, which cooperates with the adjustment slider 26. Therefore, the assembly frame 52 cannot rotate relative to the lever body 27. The rotationally fixed connection is achieved by the adjustment shaft 53 extending along the adjustment axis 28. In an alternative embodiment, the lever body 27 and the assembly frame 52 can be accurately positioned relative to each other, for example, via a pin connection or a screw connection, without releasing the fixation that results in a certain degree of freedom of displacement about the adjustment axis . As another alternative, the assembly frame 52 of the lever body 27 and the stitch regulator gear 49 may be designed as an integral piece.

The stitch regulator gear 49 transmits the driving motion transmitted by the arm shaft 15 via the eccentric lever 53a into the driving motion of the transmission lever 50.

9 and 10, the short stitch adjusting device 54 for specifying the short stitch length in the sewing workpiece conveyance direction x is described below. Short stitch length is especially used for the line segment at the end of the seam. The short stitch length is less than the small forward stitch length described above.

FIG. 9 shows the short stitch adjustment device 54 in the neutral position. In this neutral position, the piston 55 designed as a short stitch setting actuator 56 retracts. The piston 55 represents the driving body of the short stitch setting driver. By the prestressing of the prestressed spring, the curved surface of the short stitch lever body 58 abuts on the free end of the piston 55.

The short stitch lever body 58 is connected to the adjustment shaft 53 in a rotationally fixed or torque-preventing manner, and the lever body 27 that cooperates with the adjustment slider 26 via the bolt 29 is also connected in a rotationally fixed manner through the adjustment shaft.

FIG. 10 shows the stitch adjusting device 54 at the position of "short stitch for line segment". The piston 55 of the short stitch setting driver 56 is extended, so that the short stitch lever body 58 rotates counterclockwise around the adjustment shaft 53 in FIGS. 9 and 10.

By pivoting the short stitch lever body 58, the stitch adjuster gear 49 is adjusted accordingly, which results in adjustment of the short stitch driver of the stitch adjuster shaft 51.

The short stitch length is specified by the short stitch stop body 59. In the "short stitch for line segment" position according to FIGS. 10 and 11, the short stitch setting driver 56 has the outer peripheral band 60 of the piston 55 hitting the curved opposing surface 61 of the short stitch stop body 59, thereby limiting and limiting the piston stroke And thus restrict and define the position of the short stitch lever body 58. The short stitch stop body 59 can be pivoted about a pivot axis 62 provided by the assembly screw 63 for the short stitch stop body 59. The assembly screw 63 thus represents the stop body axis.

The designation of the stop position is made by the corresponding pivoting of the short-stitch stop body 59 around the stop body axis 63. The pivoting is achieved by rotating the threaded pin 64, which is rotated into the short stitch stop body 59 and fixed against the housing The fixed wall 65 is supported on the machine side. The adjustment head 66 of the threaded pin 64 can be freely accessed from the outside.

The drives 16, 32, 38 and 56 are controlled by a central control device 67 shown in dashed lines in FIG.

The sewing machine 1 allows a stitch amount of more than 2,000 stitches per minute, and is usually 3,000 stitches per minute.

The sewing machine 1 can sew a sewing workpiece with a material thickness of 4 mm or more.

The thickness (thickness) of the needle of the sewing machine 1 may be greater than 1.1 mm in diameter (needle of nominal size 110). The thickness of the needle can be greater than 1.25mm, can be greater than 1.5mm, can be greater than 1.75mm, and can also be greater than 2mm.

The wire thickness can be greater than 0.3 mm in diameter. In particular, the wire thickness may be greater than the nominal size of 60 (60m wire weight is 1g). In particular, the thickness of the wire may be greater than 0.5 mm, greater than 0.7 mm, greater than 0.9 mm or 1 mm in diameter.

10‧‧‧support plate

25‧‧‧ Stitch length adjusting device

26‧‧‧stop unit, adjustment slider

27‧‧‧Lever body

28‧‧‧Adjust the axis

29‧‧‧bolt

30‧‧‧ Forward stitch bending area

31‧‧‧backward curved area

32‧‧‧Set driver

39‧‧‧piston

40‧‧‧curved surface

35‧‧‧First forward adjustment device

36‧‧‧Spherical free end

37、41‧‧‧Lever surface

38‧‧‧Set driver

42‧‧‧Spherical free end

43‧‧‧Second forward adjustment device

44‧‧‧ Calibration axis

46‧‧‧Eccentric parts

49‧‧‧stitch regulator gear

50‧‧‧ Transmission lever

51‧‧‧Conveying drive shaft

52‧‧‧Assembly frame

53‧‧‧Adjustment shaft

53a‧‧‧Eccentric lever

Claims (13)

A stitch length adjusting device for a sewing machine, which has a stop unit for specifying a stop for a lever body that can be adjusted between the following positions by pivoting about an adjustment axis : - forward stitch stop position, the forward stitch stop position is used to specify the conveying movement of the sewing workpiece conveyor in the sewing workpiece conveying direction; - backward stitch stop position, the backward stitch stop position It is used to specify the conveying motion of the sewing workpiece conveyor in the direction opposite to the sewing workpiece conveying direction, including the stitch regulator gear, which is connected to the lever body on the one hand and Conveyor drive shaft;-wherein the assembly frame of the stitch regulator gear is connected to the lever body in a rotationally fixed manner. The stitch length adjustment device according to claim 1, wherein the stop unit is designed as an adjustment slider for the lever body, and the adjustment slider can be pivoted around the adjustment axis Adjust between the following positions: - The forward stitch slider position, which forms the forward stitch stop position, is used to specify the sewing workpiece conveyor in the sewing workpiece transport direction Conveyor movement; - the position of the backward stitch slider, the position of the backward stitch slider forms the The backward stitch stop position is used to specify the conveying movement of the sewing workpiece conveyor in the direction opposite to the sewing workpiece conveying direction. The stitch length adjustment device according to claim 1, characterized in that it includes an adjustment shaft extending along the adjustment axis, and the lever body and the assembly frame are connected to the adjustment in a rotationally fixed manner axis. The stitch length adjusting device according to claim 1, characterized by comprising a setting driver operatively connected to the lever body to set the lever body. The stitch length adjusting device according to claim 1, characterized in that it includes a first forward stitch setting device for passing at least one stopper in the stopper unit The shift specifies the large forward stitch length in the conveying direction of the sewing workpiece. The stitch length adjusting device according to claim 5, characterized in that it includes a second forward stitch setting device for passing at least one stopper in the stopper unit The shift specifies the second smaller forward stitch length in the conveying direction of the sewing workpiece. The stitch length adjusting device according to claim 1, characterized by comprising a short stitch setting device for making a short line for a short stitch lever body connected to the stitch regulator gear by The stitch stop body is shifted to specify the short stitch length in the sewing workpiece conveying direction, which is shorter than the forward stitch length. The stitch length adjusting device according to claim 7, characterized in that The assembly frame of the stitch regulator gear is connected to the short stitch lever body in a rotationally fixed manner. The stitch length adjusting device according to claim 7, wherein the stop position of the short stitch lever body on the short stitch stop body can be made by surrounding the short stitch stop body around the stop body Specify the axis shift. The stitch length adjustment device according to claim 7, characterized by comprising a short stitch setting driver operatively connected to the short stitch lever body to set the short stitch lever body. The stitch length adjusting device according to claim 10, characterized in that the designation of the stop position of the short stitch lever body on the short stitch stop body is to set the driver body of the driver by specifying the short stitch The stop on the short stitch stop body is performed. The stitch length adjusting device according to claim 1, characterized by comprising a calibration device for adjusting the length ratio between the forward stitch length and the backward stitch length. A sewing machine having a stitch length adjusting device for a sewing machine, the stitch length adjusting device:-has a stop unit for specifying a stop of the lever body, the lever body can pass around the adjustment axis Pivot to adjust between the following positions: - Forward stitch stop position, which is used to specify the feed of the sewing workpiece conveyor in the sewing workpiece conveying direction Feed motion; - backward stitch stop position, the backward stitch stop position is used to specify the conveying movement of the sewing workpiece conveyor in the opposite direction of the sewing workpiece conveying direction,-including the stitch regulator gear, the The stitch adjuster gear is connected to the lever body on the one hand and to the conveyor drive shaft on the other hand;-wherein the assembly frame of the stitch adjuster gear is connected to the lever body in a rotationally fixed manner .

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