Needle distance adjustment mechanism and sewing machine having the same

Abstract

The present invention relates to a stitch length adjustment mechanism and a sewing machine having the same, wherein the stitch length adjustment mechanism comprises: a driving source; a transmission rod group, one end of which is connected to the driving source; a stitch length adjustment shaft, which is connected to the other end of the transmission rod group and can rotate through a preset angle under the drive of the transmission rod group; a first adjustment crank, which is connected to the stitch length adjustment shaft so as to swing along with the rotation of the stitch length adjustment shaft; a second adjustment crank, one end of which is connected to the first adjustment crank and the other end of which has a first fulcrum, and when the first adjustment crank swings along with the stitch length adjustment shaft, it can drive the second adjustment crank to move so as to adjust the position of the first fulcrum; and a crank connecting rod, one end of which is hinged to the first fulcrum and the other end of which is used to drive the differential feed crank to swing, and when the first fulcrum is in different positions, the swing amplitude of the differential feed crank is different, and the mechanism can automatically adjust the stitch length without manual unlocking / locking.

Description

Technical Field

[0001] The invention relates to the field of sewing equipment, in particular to a needle distance adjustment mechanism and a sewing machine having the same. Background Art

[0002] In the structure of a traditional sewing machine, the main function of the cloth feeding mechanism is to drive the cloth feeding rack to perform reciprocating elliptical motion through the main shaft to form a cloth feeding trajectory, thereby continuously lifting and pulling the cloth on the needle plate, so as to continuously drag the cloth to the machine head, and the needle and the curved needle in the machine head cooperate to form stitches on the cloth in a preset manner, thereby completing the sewing and locking operation of the textile. The elliptical motion of the cloth feeding rack can be regarded as the superposition of two directions of motion: the reciprocating swing of the cloth feeding rack in the horizontal direction, and the lifting and lowering of the teeth in the up and down directions. Among them: the amplitude of the reciprocating swing of the cloth feeding rack in the horizontal direction directly determines the cloth feeding speed, and under the premise that the movement speed of the needle and the curved needle in the machine head is constant, the cloth feeding speed further determines the stitch length. Therefore, in order to flexibly adjust the stitch length, existing sewing machines are often equipped with related structures for stitch length adjustment.

[0003] In an existing stitch length adjustment structure, a feed connecting rod for driving the differential feed crank to swing, and a ratchet pawl locking structure for changing the swing amplitude of the feed connecting rod are provided on the main shaft. When the stitch length needs to be changed, the pawl is lifted and released from the ratchet wheel through an external control force. The main shaft rotates further in this state, and the feed connecting rod rotates around the rotation axis of the main shaft through a preset angle, thereby changing the swing amplitude of the feed connecting rod. The differential feed crank connected thereto drives the feed tooth frame to change its horizontal swing amplitude accordingly, thereby realizing the adjustment of the stitch length.

[0004] In the above-mentioned stitch length adjustment structure, since the matching relationship between the pawl and the ratchet wheel needs to be manually released and the two need to be matched again after the stitch length adjustment is completed, the adjustment process is inconvenient and is not conducive to the automatic control and efficient operation of the sewing machine. Summary of the invention

[0005] In view of this, it is necessary to provide an improved stitch length adjustment mechanism and a sewing machine having the same, wherein the stitch length adjustment mechanism can automatically adjust the stitch length without manual unlocking / locking.

[0006] The present invention first provides a needle distance adjustment mechanism, comprising:

[0007] Driving source;

[0008] A transmission rod group, one end of which is connected to the driving source;

[0009] A needle distance adjustment shaft is connected to the other end of the transmission rod group and can rotate through a preset angle along with the driving source under the drive of the transmission rod group;

[0010] a first adjusting crank connected to the stitch length adjusting shaft so as to swing along with the rotation of the stitch length adjusting shaft;

[0011] a second adjusting crank, one end of which is connected to the first adjusting crank and the other end of which has a first fulcrum, and when the first adjusting crank swings with the stitch length adjusting shaft, the second adjusting crank can be driven to move to adjust the position of the first fulcrum; and

[0012] A crank connecting rod has one end hinged to the first fulcrum, and the other end is used to drive the differential cloth feeding crank to swing. When the first fulcrum is at different positions, the swing amplitude of the differential cloth feeding crank is different.

[0013] With such a configuration, the driving source drives the transmission rod group to move, so that the stitch length adjustment shaft deflects at a preset angle around a certain axis, and the first adjustment crank connected to the stitch length adjustment shaft swings through an angle as the stitch length adjustment shaft rotates, and the second adjustment crank connected to the first adjustment crank further moves to a certain amplitude as the first adjustment crank swings, so that the position of the first fulcrum on the second adjustment crank changes in a preset manner; the crank connecting rod is connected to the first fulcrum, and when the position of the first fulcrum changes, the swing amplitude of the differential feed crank on the crank connecting rod changes, so that the horizontal swing amplitude of the feed tooth frame cooperating with the differential feed crank changes accordingly, thereby realizing the adjustment of the stitch length. In this adjustment method, the rotation of the driving source can directly adjust the stitch length without manually loosening the ratchet pawl structure. When the driving source has no action output, the stitch length adjustment mechanism as a whole will not move, which is equivalent to locking. At the same time, the rotation angle of the driving source directly determines the amplitude of the stitch length adjustment. When the driving source adopts a stepper motor, servo motor, etc., its rotation angle can be precisely controlled, so that the stitch length can be precisely adjusted.

[0014] In one embodiment, the transmission rod group includes a driving connecting rod, a transmission connecting rod and a needle distance adjustment connecting rod, wherein:

[0015] The driving connecting rod is connected to the output end of the driving source and can rotate therewith;

[0016] One end of the stitch length adjustment connecting rod is connected to the stitch length adjustment shaft and is used to drive the stitch length adjustment shaft to rotate around a certain axis;

[0017] The transmission connecting rod is connected between the other end of the needle distance adjusting connecting rod and the driving connecting rod.

[0018] With such arrangement, the driving connecting rod, the transmission connecting rod and the stitch length adjustment connecting rod are used as the transmission rod group, so that the motion output of the driving source can be reliable and the transmission structure is simple.

[0019] In one embodiment, the needle distance adjustment link is arranged in a bent rod or strip shape, and includes a first rod segment, a second rod segment and a third rod segment that are fixed to or integrated with each other, wherein: one end of the first rod segment is connected to the transmission link, and is transmission-connected with the transmission link and the drive link roughly in the same plane; the second rod segment extends from the other end of the first rod segment in a direction roughly parallel to the axis of the output end of the drive source; the third rod segment extends from one end of the second rod segment in a direction roughly parallel to the first rod segment.

[0020] With such arrangement, the second rod section extends in a direction substantially parallel to the axis of the output end of the driving source, so that the needle distance adjustment shaft and the driving source are relatively closer, thereby making the overall spatial size of the needle distance adjustment mechanism smaller.

[0021] In one of the embodiments, the stitch length adjustment shaft has a rotating connection portion, the rotating connection portion is provided with a limiting groove extending radially along the stitch length adjustment shaft, and the end of the stitch length adjustment connecting rod is inserted and fixed to the limiting groove.

[0022] In one embodiment, a limiting sleeve is provided on the stitch length adjustment shaft, and the limiting sleeve can be embedded in the housing of the sewing machine so that the stitch length adjustment shaft can rotate relative to the housing in the limiting sleeve.

[0023] With such arrangement, the limiting sleeve is embedded in the housing of the sewing machine, thereby limiting the position of the rotation axis of the stitch adjustment shaft and avoiding wear between the stitch adjustment shaft and the housing.

[0024] A second aspect of the present invention provides a sewing machine, comprising a main shaft, a cloth feeding connecting rod, and the above-mentioned needle distance adjustment mechanism, wherein:

[0025] One end of the cloth feeding connecting rod is connected to the main shaft and can swing back and forth with the rotation of the main shaft, and the other end is rotatably connected to the first fulcrum.

[0026] In one embodiment, the sewing machine further includes a cloth feed eccentric sleeve, the cloth feed eccentric sleeve includes a concentric portion concentric with a certain axial segment of the main shaft, and an eccentric portion eccentrically arranged relative to the concentric portion, and the cloth feed connecting rod is sleeved to the eccentric portion.

[0027] In one of the embodiments, a needle bearing is further provided at the sleeve joint between the eccentric portion and the cloth feeding connecting rod.

[0028] In one of the embodiments, a stopper for limiting the axial position of the needle bearing is also provided on the main shaft.

[0029] In one of the embodiments, the sewing machine further comprises a differential cloth feed shaft;

[0030] The differential cloth feeding crank comprises a mounting portion sleeved on the differential cloth feeding shaft, a hinge portion for rotationally connecting the crank connecting rod, and a driving portion for driving the cloth feeding tooth frame to reciprocate and swing in a horizontal direction.

[0031] With this arrangement, the hinged portion of the differential feed crank is directly connected to the crank connecting rod, which is equivalent to the motion output by the crank connecting rod being directly transmitted to the feed tooth frame through the differential feed crank, eliminating the differential feed shaft as a motion transmission medium, and making the motion transmission simpler and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a needle distance adjustment mechanism according to an embodiment of the present invention, wherein the figure shows components related to the needle distance adjustment mechanism in order to reflect the connection relationship between the needle distance adjustment mechanism and other positions of the sewing machine;

[0033] Figure 2 for Figure 1 Another perspective view of the structure shown in;

[0034] Figure 3 for Figure 1 Schematic diagram of the decomposed structure of the structure shown in .

[0035] 100, needle distance adjustment mechanism; 11, driving source; 12, transmission rod group; 121, driving connecting rod; 122, transmission connecting rod; 123, needle distance adjustment connecting rod; 1231, first rod section; 1232, second rod section; 1233, third rod section; 13, needle distance adjustment shaft; 131, rotating connecting part; 1311, limiting groove; 14, first adjusting crank; 15, second adjusting crank; 16, crank connecting rod; 17, limiting sleeve; 18, rotating shaft;

[0036] 200, spindle;

[0037] 300, differential cloth feeding crank; 31, mounting portion; 32, hinge portion; 33, driving portion;

[0038] 400, differential feed shaft;

[0039] 500, cloth feeding connecting rod;

[0040] 600, cloth feeding eccentric sleeve; 61, concentric part; 62, eccentric part;

[0041] 700. Block. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly mounted on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component at the same time. When a component is considered to be "fixed to" another component, it may be directly fixed on the other component or there may be a central component at the same time.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more related listed items.

[0045] The stitch length adjustment mechanism 100 according to one embodiment of the present invention is applied to a sewing machine and is used to change the horizontal swing amplitude of the feed tooth frame in the sewing machine, thereby achieving stitch length adjustment. In order to clearly express the stitch length adjustment principle of sewing using the stitch length adjustment mechanism 100, some parts of the sewing machine will be introduced in the following description, such as Figures 1 to 3 The main shaft 200, the differential feed crank 300, the differential feed shaft 400 and the feed connecting rod 500 shown in FIG.

[0046] refer to Figures 1 to 3 As shown in the figure, the needle distance adjustment mechanism 100 includes a driving source 11, a transmission rod group 12, a needle distance adjustment shaft 13, a first adjustment crank 14, a second adjustment crank 15 and a crank connecting rod 16, wherein: one end of the transmission rod group 12 is connected to the output shaft of the driving source 11, and the other end is connected to the needle distance adjustment shaft 13. When the output shaft of the driving source 11 rotates, the transmission rod group 12 moves accordingly to drive the needle distance adjustment shaft 13 to rotate through a preset angle.

[0047] In one embodiment, a limiting sleeve 17 is sleeved on the stitch adjustment shaft 13, and the limiting sleeve 17 is embedded in the housing of the sewing machine, so that the stitch adjustment shaft 13 can rotate relative to the housing of the sewing machine in the inner hole of the limiting sleeve 17. Furthermore, the limiting sleeve 17 can be a copper sleeve with good wear resistance.

[0048] One end of the first adjusting crank 14 is connected to the shaft section of the needle distance adjusting shaft 13 extending out of the limiting sleeve 17, and the two can be circumferentially linked. The other end of the first adjusting crank 14 extends away from the axis of the needle distance adjusting shaft 13 and is connected to the second adjusting crank 15. In this way, the rotation of the needle distance adjusting shaft 13 can drive the first adjusting crank 14 to swing through a certain angle, thereby causing the second adjusting crank 15 to move accordingly.

[0049] refer to Figure 1 As shown in the mark in, one end of the second adjustment crank 15 is connected to the end of the first adjustment crank 14 away from the axial direction of the stitch length adjustment shaft 13, and the other end has a first fulcrum X. When the second adjustment crank 15 changes position with the swing of the first adjustment crank 14, the position of the first fulcrum X also changes accordingly. In some embodiments, a rotating shaft 18 is passed through the end of the second adjustment crank 15 away from the first adjustment crank 14, and the rotation center point of the rotating shaft 18 is the position of the first fulcrum X.

[0050] One end of the crank connecting rod 16 is connected to the first fulcrum X. In the embodiment with the rotating shaft 18, the crank connecting rod 16 is rotatably connected to the rotating shaft 18. The other end of the crank connecting rod 16 is connected to the differential feed crank 300 to drive the differential feed crank 300 to swing. As mentioned above, the position of the first fulcrum X will change with the action of the second adjusting crank 15. Therefore, the amplitude of the swinging motion of the crank connecting rod 16 will also change accordingly, and finally the differential feed crank 300 will swing along the axis of rotation. Figure 1 The swing amplitude in the direction of the solid arrow indicated in the figure changes, and accordingly, the feed tooth frame has different horizontal swing amplitudes as the differential feed crank 300 swings at different amplitudes.

[0051] Continue to refer Figure 1 As shown in the embodiment shown in the figure, the transmission rod group 12 includes a driving link 121, a transmission link 122 and a stitch length adjustment link 123, wherein: one end of the driving link 121 is connected to the output shaft of the driving source 11, so as to swing or rotate a full circle with the rotation of the output shaft of the driving source 11; the other end of the driving link 121 is connected to one end of the transmission link 122, and the other end of the transmission link 122 is connected to one end of the stitch length adjustment link 123. In this way, the transmission link 122 transmits the movement of the driving link 121 to the stitch length adjustment link 123.

[0052] exist Figure 1 Based on the combination Figure 2As shown in the embodiment shown in the figure, the needle distance adjustment link 123 includes a first rod segment 1231, a second rod segment 1232 and a third rod segment 1233 which are connected or integrally arranged in sequence, and the overall needle distance adjustment link 123 is arranged in a bent rod or strip shape. One end of the first rod segment 1231 is connected to the transmission link 122, and the driving link 121, the transmission link 122 and the first rod segment 1231 are roughly transmitted in one plane. In other words, ignoring the thickness and hinge of the three rod-shaped members, the three constitute a connecting rod structure in the plane; the second rod segment 1232 extends from one end of the first rod segment 1231 away from the transmission link 122, in a direction roughly parallel to the output axis of the driving source 11; the third rod segment 1233 extends from one end of the second rod segment 1232 in a direction roughly parallel to the first rod segment 1231, and is connected to the needle distance adjustment shaft 13.

[0053] refer to Figure 2 As shown in, in one embodiment, one end of the needle distance adjustment shaft 13 extends out of the limit sleeve 17 and has a rotating connection portion 131, and a limit groove 1311 extending radially along the needle distance adjustment shaft 13 is provided on the end face of the rotating connection portion 131, and the third rod segment 1233 is inserted into the limit groove 1311 and fixed, so that the needle distance adjustment connecting rod 123 and the needle distance adjustment shaft 13 establish a reliable circumferential linkage relationship.

[0054] From the geometric relationship, it can be seen that through the setting of the bent needle distance adjustment link 123 and the setting of the limit groove 1311 on the needle distance adjustment shaft 13, the axial direction of the needle distance adjustment shaft 13 is roughly parallel to the output axial direction of the drive source 11 in the assembled state, and in the radial direction, the needle distance adjustment shaft 13 can be set as close to the side of the drive source 11 as possible by selecting an appropriate length of the first rod segment 1231, thereby reducing the installation space required for the entire needle distance adjustment mechanism 100.

[0055] Combination Figure 1 and Figure 2As shown in , the main shaft 200 in the sewing machine rotates, and the feed connecting rod 500 connected thereto is used to drive the crank connecting rod 16 to swing back and forth. When the above-mentioned stitch length adjustment mechanism 100 is used, the action of the driving source 11 can change the position of the first fulcrum X on the second adjustment crank 15, and the feed connecting rod 500 and the crank connecting rod 16 are both connected to the first fulcrum X. Therefore, the reciprocating swing amplitude output from the feed connecting rod 500 to the crank connecting rod 16 changes, thereby realizing the change of the swing amplitude of the feed tooth frame driven by the differential feed crank 300. This stitch length adjustment method is completely realized by driving the driving source 11 to drive the connecting rod structure, the rotating shaft and other simple transmission parts. The overall movement and transmission relationship are simple, which is conducive to improving the movement accuracy of the stitch length adjustment mechanism. At the same time, the self-locking performance of the driving source 11 can also be used to realize the self-locking of the stitch length adjustment mechanism when it is not necessary. Compared with the existing ratchet pawl locking / unlocking structure, the manual unlocking process is omitted, which is conducive to the automatic control and precise adjustment of the sewing machine.

[0056] The second aspect of the embodiment of the present invention further provides a sewing machine, comprising the above-mentioned needle distance adjustment mechanism 100. Figures 1 to 3 As shown in the figure, the sewing machine further includes a cloth feeding eccentric sleeve 600 sleeved on the main shaft 200, and the cloth feeding eccentric sleeve 600 includes a concentric portion 61 and an eccentric portion 62. The cloth feeding eccentric sleeve 600 is provided with a through hole for accommodating the corresponding shaft section of the main shaft 200 to pass through, and the through hole penetrates the concentric portion 61 and the eccentric portion 62. The eccentric portion 62 referred to here means that the eccentric portion 62 is arranged away from the center of the concentric portion 61. One end of the cloth feeding connecting rod 500 is sleeved on the eccentric outer peripheral surface of the eccentric portion 62.

[0057] In some embodiments, a needle bearing is sleeved on the eccentric portion 62, and the outer ring of the needle bearing is connected to the cloth feeding connecting rod 500, thereby reducing the friction between the cloth feeding connecting rod 500 and the eccentric portion 62. In addition, in order to limit the axial position of the needle bearing, a stopper 700 is also provided on the main shaft 200, and the stopper 700 abuts against one end side of the axial direction of the needle roller and limits its axial displacement.

[0058] refer to Figure 3 As shown in , the sewing machine also includes a differential cloth feed shaft 400, and the differential cloth feed crank 300 includes a mounting portion 31, an articulated portion 32 and a driving portion 33, wherein: the differential cloth feed shaft 400 rotates relative to the sewing machine housing, the mounting portion 31 is connected to the differential cloth feed shaft 400 and circumferentially linked, so that the differential cloth feed crank 300 reciprocates around the axis of the differential cloth feed shaft 400; the articulated portion 32 is used to connect the crank connecting rod 16, so that the swing of the crank connecting rod 16 can be input to the differential cloth feed crank 300; the driving portion 33 is directly used to drive the swing amplitude of the cloth feed tooth frame in the horizontal direction. The driving portion 33 is along Figure 1The feed tooth frame can swing in the direction of the solid arrow shown, and the longitudinal component of the swinging motion can be released through the longitudinal slide groove, and only the feed tooth frame can be driven to swing horizontally.

[0059] Since the crank connecting rod 16 directly drives the differential cloth feed crank 300 to move, the movement does not need to be transmitted through the differential cloth feed shaft 400, and the movement accuracy is higher.

[0060] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, appropriate changes and modifications to the above embodiments are within the scope of protection claimed by the present invention.

Claims

1. A needle distance adjustment mechanism, characterized in that: include: Driving source (11); A transmission rod group (12), one end of which is connected to the driving source (11); A needle distance adjustment shaft (13) connected to the other end of the transmission rod group (12) and capable of rotating through a preset angle along with the driving source (11) under the drive of the transmission rod group (12); A first adjustment crank (14) connected to the needle distance adjustment shaft (13) so as to swing along with the rotation of the needle distance adjustment shaft (13); a second adjusting crank (15), one end of which is connected to the first adjusting crank (14), and the other end of which has a first fulcrum, and when the first adjusting crank (14) swings along with the stitch length adjustment shaft (13), it can drive the second adjusting crank (15) to move, so as to adjust the position of the first fulcrum; and A crank connecting rod (16), one end of which is hinged to the first fulcrum, and the other end of which is used to drive the differential cloth feeding crank (300) to swing, and when the first fulcrum is at different positions, the swing amplitude of the differential cloth feeding crank (300) is different; The transmission rod assembly (12) comprises a driving connecting rod (121), a transmission connecting rod (122) and a needle distance adjustment connecting rod (123), wherein: The driving connecting rod (121) is connected to the output end of the driving source (11) and can rotate therewith; One end of the needle distance adjustment connecting rod (123) is connected to the needle distance adjustment shaft (13) and is used to drive the needle distance adjustment shaft (13) to rotate; The transmission connecting rod (122) is connected between the other end of the needle distance adjustment connecting rod (123) and the driving connecting rod (121); A limiting sleeve (17) is sleeved on the stitch length adjustment shaft (13), and the limiting sleeve (17) can be embedded in a housing of a sewing machine so that the stitch length adjustment shaft (13) can rotate relative to the housing in a fixed axis within the limiting sleeve (17).

2. The needle distance adjustment mechanism according to claim 1, characterized in that: The stitch length adjustment connecting rod (123) is arranged in a bent rod or strip shape, and comprises a first rod segment (1231), a second rod segment (1232) and a third rod segment (1233) which are fixed to or integrated with each other, wherein: one end of the first rod segment (1231) is connected to the transmission connecting rod (122), and is transmission-connected with the transmission connecting rod (122) and the driving connecting rod (121) approximately in the same plane; the second rod segment (1232) extends from the other end of the first rod segment (1231) in a direction approximately parallel to the axis of the output end of the driving source (11); and the third rod segment (1233) extends from one end of the second rod segment (1232) in a direction approximately parallel to the first rod segment (1231).

3. The needle distance adjustment mechanism according to claim 1, characterized in that: The needle distance adjustment shaft (13) has a rotating connection portion (131), the rotating connection portion (131) is provided with a limiting groove (1311) extending in the radial direction of the needle distance adjustment shaft (13), and the end of the needle distance adjustment connecting rod (123) is plugged and fixed to the limiting groove (1311).

4. A sewing machine, characterized in that: It comprises a main shaft (200), a cloth feeding connecting rod (500), and a needle distance adjustment mechanism (100) as claimed in any one of claims 1 to 3, wherein: One end of the cloth feeding connecting rod (500) is connected to the main shaft (200) and can swing back and forth as the main shaft (200) rotates, and the other end is rotationally connected to the first fulcrum.

5. The sewing machine according to claim 4, characterized in that The sewing machine further comprises a cloth feeding eccentric sleeve (600), the cloth feeding eccentric sleeve (600) comprising a concentric portion (61) concentric with a certain shaft segment of the main shaft (200), and an eccentric portion (62) eccentrically arranged relative to the concentric portion (61), and the cloth feeding connecting rod (500) is sleeved on the eccentric portion (62).

6. The sewing machine according to claim 5, characterized in that A needle bearing is also provided at the sleeve connection between the eccentric portion (62) and the cloth feeding connecting rod (500).

7. The sewing machine according to claim 6, characterized in that The main shaft (200) is also provided with a stopper (700) for limiting the axial position of the needle roller bearing.

8. The sewing machine according to claim 4, characterized in that The sewing machine further comprises a differential cloth feeding shaft (400); The differential cloth feed crank (300) comprises a mounting portion (31) sleeved on the differential cloth feed shaft (400), a hinge portion (32) for rotationally connecting the crank connecting rod (16), and a driving portion (33) for driving the cloth feed tooth frame to reciprocate in a horizontal direction.

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