Sewing machine capable of conveniently adjusting stitch length

Abstract

The utility model provides a sewing machine capable of conveniently adjusting stitch length, a first transmission assembly comprises a first connecting rod, a first motor is hinged with a first end of the first connecting rod through a first cam, and a second end of the first connecting rod is connected with a feeding assembly; when the first motor works, the first connecting rod drives the feeding assembly to work for feeding; the second motor is connected with the first connecting rod through the second transmission assembly, and when the second motor works, the first connecting rod is changed by a certain angle through the second transmission assembly, so that when the first motor works, the feeding amplitude of the feeding assembly is changed to adjust the stitch length. According to the sewing machine capable of conveniently adjusting the stitch length, the second motor and the second transmission assembly are arranged, the second motor works, the angle of the first connecting rod in the first transmission assembly can be adjusted through the second transmission assembly, and therefore the feeding amplitude of the feeding assembly can be adjusted, and the stitch length can be adjusted.

Description

Technical Field

[0001] The utility model relates to sewing machinery and equipment, in particular to a sewing machine capable of conveniently adjusting the stitch length. Background Art

[0002] At present, most of the sewing machines used in the market are operated manually to lift the presser foot, adjust the stitch length and reverse stitch, and the three actions are relatively independent, which greatly reduces the workers' work efficiency and increases the work intensity. Only a small number of sewing machines have been improved to use electromagnets or air cylinders to achieve automatic presser foot lifting. The stitch length adjustment is still achieved by turning the stitch length adjustment knob, and reverse stitching is also achieved by pressing the reverse stitch wrench. On the other hand, the use of electromagnets or air cylinders to achieve automatic presser foot lifting has the disadvantages of loud noise and instability, especially the use range of the air cylinder mode is relatively narrow. Utility Model Content

[0003] In order to solve the above problems, it is necessary to provide a sewing machine that can automatically adjust the stitch length.

[0004] The utility model provides a sewing machine capable of conveniently adjusting the stitch length, comprising a first motor, a second motor, a first transmission assembly, a second transmission assembly and a feed assembly; the first transmission assembly comprises a first connecting rod, the first motor is hinged to the first end of the first connecting rod via a first cam, and the second end of the first connecting rod is connected to the feed assembly; when the first motor is working, the first connecting rod drives the feed assembly to work and feed the material; the second motor is connected to the first connecting rod via the second transmission assembly, and when the second motor is working, the second transmission assembly causes the first connecting rod to change a certain angle, so that when the first motor is working, the feeding amplitude of the feed assembly can be changed to adjust the stitch length.

[0005] Preferably, the first end of the first connecting rod is an opening structure with two parallel sides, the outer circumference of the first cam is a U-shaped groove, the U-shaped groove is provided with a profile adapted to the opening structure, and the first connecting rod is adaptively connected to the profile.

[0006] Preferably, it also includes a presser foot lifting assembly; the presser foot lifting assembly includes a presser foot lifting cam, a presser foot lifting rod, a first lever, a second lever, a connecting plate and a presser foot lifting assembly, and the presser foot lifting rod is in contact with the presser foot lifting cam; the middle parts of the first lever and the second lever are both hinged to the frame, the presser foot lifting rod is fixedly connected to one end of the first lever, the other end of the first lever and the first end of the second lever are respectively hinged to the connecting plate, and the second end of the second lever is connected to the presser foot lifting assembly; the presser foot lifting cam is connected to the output shaft of the second motor.

[0007] Preferably, the second transmission assembly includes a stitch length adjustment cam, a stitch length adjustment crank, a stitch length adjustment connecting rod, a first feed adjustment rod, and a second feed adjustment rod; the stitch length adjustment cam is connected to the output shaft of the second motor; the first position of the stitch length adjustment crank is hinged to the first rotating shaft on the frame, the second position is a position that can abut the stitch length adjustment cam, and the third position is hinged to the first end of the stitch length adjustment connecting rod, and the first position, the second position and the third position are not on the same straight line; the second end of the stitch length adjustment connecting rod is hinged to the first end of the first feed adjustment rod; the second end of the first feed adjustment rod is hinged to the frame; the middle part of the first feed adjustment rod is connected to the first end of the second feed adjustment rod, and the second end of the second feed adjustment rod is hinged to the middle part of the first connecting rod.

[0008] Preferably, the presser foot lifting cam and the stitch length adjusting cam are sleeved together to form an integral sleeve and are arranged on the output shaft of the second motor, or the presser foot lifting cam and the stitch length adjusting cam are respectively sleeved on the output shaft of the second motor.

[0009] Preferably, the second transmission assembly includes a needle pitch eccentric wheel, a needle pitch adjustment connecting rod, a first feed adjustment rod, and a second feed adjustment rod; the needle pitch eccentric wheel is eccentrically connected to the output shaft of the second motor; the needle pitch eccentric wheel is rotatably connected to the first end of the needle pitch adjustment connecting rod, and the second end of the needle pitch adjustment connecting rod is hinged to the first end of the first feed adjustment rod; the second end of the first feed adjustment rod is hinged to the frame; the middle part of the first feed adjustment rod is connected to the first end of the second feed adjustment rod, and the second end of the second feed adjustment rod is hinged to the middle part of the first connecting rod.

[0010] Preferably, the presser foot lifting cam and the stitch length eccentric wheel are integrally formed and sleeved together to form an integral sleeve and arranged on the output shaft of the second motor, or the presser foot lifting cam and the stitch length eccentric wheel are respectively sleeved on the output shaft of the second motor.

[0011] Preferably, the second transmission assembly includes a stitch length crank, a stitch length adjustment connecting rod, a first feed adjustment rod, and a second feed adjustment rod; the first end of the stitch length crank is fixedly connected to the output shaft of the second motor; the stitch length crank is rotatably connected to the first end of the stitch length adjustment connecting rod, and the second end of the stitch length adjustment connecting rod is hinged to the first end of the first feed adjustment rod; the second end of the first feed adjustment rod is hinged to the frame; the middle part of the first feed adjustment rod is connected to the first end of the second feed adjustment rod, and the second end of the second feed adjustment rod is hinged to the middle part of the first connecting rod.

[0012] Preferably, the feeding assembly includes a feeding shaft, a first slider, a second slider and a tooth-lifting rocker arm; the feeding shaft is fixedly connected to the first slider, the first slider is provided with an accommodating space for accommodating the second slider, and the second slider has a gap with the first slider when it is located in the accommodating space, the tooth-lifting rocker arm is fixedly connected to the second slider, and the tooth-lifting rocker arm is hinged to the frame; when the first motor rotates, the first connecting rod drives the feeding shaft to rotate, thereby driving the tooth-lifting rocker arm to move back and forth to realize feeding.

[0013] Preferably, it also includes a presser foot lifting assembly; the presser foot lifting assembly includes a presser foot lifting cam, a presser foot lifting rod, a first lever, a second lever, a connecting plate and a presser foot lifting assembly, and the presser foot lifting rod is in contact with the presser foot lifting cam; the middle parts of the first lever and the second lever are both hinged to the frame, the presser foot lifting rod is fixedly connected to one end of the first lever, the other end of the first lever and the first end of the second lever are respectively hinged to the connecting plate, and the second end of the second lever is connected to the presser foot lifting assembly; the presser foot lifting cam is connected to the output shaft of the second motor.

[0014] Preferably, the presser foot lifting assembly includes a pressure rod, the second end of the second lever is provided with a lap groove, and the pressure rod is lapped on the lap groove of the second lever.

[0015] Preferably, one end of the presser foot lifting rod is abutted against the presser foot lifting cam through a fisheye joint; the fisheye joint is also connected through a roller and a second connecting rod, the fisheye joint is hinged to the roller, the roller is fixedly connected to the first end of the second connecting rod, and the second end of the second connecting rod is hinged to the second rotating shaft on the frame.

[0016] Compared with the prior art, the sewing machine with convenient stitch adjustment provided by the present invention has the following advantages:

[0017] The utility model provides a sewing machine capable of conveniently adjusting the stitch length. By setting a second motor and a second transmission assembly, when the second motor is working, the angle of the first connecting rod in the first transmission assembly can be adjusted through the second transmission assembly, thereby adjusting the feeding amplitude of the feeding assembly to adjust the stitch length. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a sewing mechanism capable of conveniently adjusting the stitch length provided by the present invention;

[0019] Figure 2 for Figure 1 Schematic diagram of a preferred embodiment for adjusting the middle needle length;

[0020] Figure 3 for Figure 1 Schematic diagram of a preferred embodiment for adjusting the middle needle length;

[0021] Figure 4 for Figure 1 Schematic diagram of the feeding component;

[0022] Figure 5 for Figure 4 Schematic diagram of the assembly of the two sliders;

[0023] Figure 6 for Figure 1 Schematic diagram of the middle presser foot assembly;

[0024] Figure 7 It is the setting method of the stitch length adjustment cam and the presser foot lifting cam or the stitch length eccentric wheel.

[0025] Reference numerals

[0026]

[0027] DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings:

[0029] Example 1

[0030] This embodiment provides a needle distance adjustment device, including a first motor, a second motor, a first transmission assembly, a second transmission assembly and a feeding assembly; the first transmission assembly includes a first connecting rod 103, the first motor is hinged to the first end of the first connecting rod 103 through a first cam 102, and the second end of the first connecting rod 103 is connected to the feeding assembly; when the first motor is working, the first connecting rod 103 drives the feeding assembly to work for feeding; the second motor 20 is connected to the first connecting rod 103 through the second transmission assembly, and when the second motor 20 is working, the second transmission assembly causes the first connecting rod 103 to change a certain angle, so that when the first motor is working, the feeding amplitude of the feeding assembly can be changed to adjust the needle distance.

[0031] When implementing it specifically, Figures 1 to 4As shown: The first transmission assembly includes a first rotating shaft 101, a first cam 102 and a first connecting rod 103. The output shaft of the first motor (not shown) is fixedly connected to the first rotating shaft 101. The first cam 102 is fixed to the first rotating shaft 101. One end of the first connecting rod 103 is rotatably mounted on the outside of the first cam 102. The other end of the first connecting rod 103 is connected to the feeding assembly. When the first motor is working, the first cam 102 can cause the first connecting rod 103 to swing, thereby causing the feeding assembly to feed. The second motor 20 is hinged to the first connecting rod 103 through the second transmission assembly; preferably, the second transmission assembly is hinged to the middle of the first connecting rod 103. When the second motor 20 is working and rotating, the second transmission assembly can cause the first connecting rod 103 to change a certain angle. Therefore, when the first motor is working, the feeding amplitude of the feeding assembly can be changed, thereby adjusting the stitch length.

[0032] The utility model provides a sewing machine capable of conveniently adjusting the stitch length. By setting a second motor 20 and a second transmission assembly, when the second motor 20 is working, the angle of the first connecting rod 103 in the first transmission assembly can be adjusted through the second transmission assembly, thereby adjusting the feeding amplitude of the feeding assembly to adjust the stitch length.

[0033] Preferably, the first end of the first connecting rod 103 is an opening structure 1031 with two parallel sides, the outer circumference of the first cam 102 is a U-shaped groove 1021, and the U-shaped groove 1021 is provided with a profile that is adapted to the opening structure, and the first connecting rod 103 is adapted to be connected to the profile.

[0034] When implementing it specifically, Figure 1 As shown: a first cam 102 having a U-shaped groove 1021 on its outer circumference, when a first connecting rod 103 having an opening structure 1031 at its end is installed to match the outer circumference of the first cam 102, when the first motor is working and rotating, the first connecting rod 103 can always match the first cam together to prevent the two from falling off.

[0035] Preferably, on the basis of the above-mentioned embodiment one, this embodiment further includes a presser foot lifting assembly; the presser foot lifting assembly includes a presser foot lifting cam 50, a presser foot lifting rod 51, a first lever 52, a second lever 53, a connecting plate 54 and a presser foot lifting rod assembly 55, and the presser foot lifting rod 51 is in contact with the presser foot lifting cam 50; the middle parts of the first lever 51 and the second lever 53 are both hinged to the frame, the presser foot lifting rod 51 is hinged to one end of the first lever 52, the other end of the first lever 52 and the first end of the second lever 53 are respectively hinged to the connecting plate 54, and the second end of the second lever 53 is connected to the presser foot lifting rod assembly 55; the presser foot lifting cam 50 is connected to the output shaft of the second motor 20.

[0036] Example 2

[0037] Preferably, if Figure 1 and Figure 2 As shown in the figure: Based on the above embodiment 1, the second transmission assembly includes a stitch length adjustment cam 201, a stitch length adjustment crank 202, a stitch length adjustment connecting rod 203, a first feed adjustment rod 204, and a second feed adjustment rod 205; the stitch length adjustment cam 201 is connected to the output shaft of the second motor 20; the first position 2021 of the stitch length adjustment crank 202 is hinged to the first rotating shaft 301 on the frame, the second position 2022 is a position that can abut against the stitch length adjustment cam 201, and the third position 2023 is a position that can abut against the stitch length adjustment cam 201. It is hinged to the first end of the stitch length adjustment link 203, and the first position 2021, the second position 2022 and the third position 2023 are not on the same straight line; the second end of the stitch length adjustment link 203 is hinged to the first end of the first feed adjustment rod 204; the second end of the first feed adjustment rod 204 is hinged to the frame; the middle part of the first feed adjustment rod 204 is connected to the first end of the second feed adjustment rod 205, and the second end of the second feed adjustment rod 205 is hinged to the middle part of the first link 103.

[0038] Preferably, the presser foot lifting cam 50 and the stitch length adjustment cam 201 are integrally formed and sleeved on the output shaft of the second motor 20, or the presser foot lifting cam 50 and the stitch length adjustment cam 201 are separately formed and sleeved on the output shaft of the second motor 20 in parallel.

[0039] In specific implementation, if the design directions of the presser foot lifting cam 50 and the stitch length adjustment cam 201 are changed at the same time, counterclockwise rotation can realize the functions of presser foot lifting and stitch length adjustment, while clockwise rotation realizes the function of reverse stitching. The presser foot lifting cam 50 and the stitch length adjustment cam 201 are both fixed to the output shaft of the motor. The two cams are linked together. Therefore, there is a phase difference between the presser foot lifting cam 50 and the stitch length adjustment cam 201 when they are designed. That is, when the presser foot lifting function is realized, the stitch length adjustment or reverse stitching function cannot be realized at the same time, or when the stitch length adjustment or reverse stitching function is realized, the presser foot lifting function cannot be realized at the same time. In order to realize these functions, the present embodiment sets the stop origin on the stitch length adjustment cam 50. Of course, the stop origin can also be set on the presser foot lifting cam 201.

[0040] In this embodiment, the presser foot lifting cam 50 and the stitch length adjustment cam 201 are separated. This has the advantage of convenient and accurate adjustment of the stop origin, which can perfectly avoid the influence caused by component errors. Of course, the presser foot lifting cam 50 and the stitch length adjustment cam 201 can also be combined into one part. The disadvantage of this is that it is difficult to adjust the origin, which is not conducive to mass production. Similarly, if they are combined into one cam, they can also be divided into two situations: clockwise and counterclockwise.

[0041] like Figure 7 In the figure, A and A' are respectively the presser foot lifting cam 50 and the stitch length adjusting cam 201, which are respectively sleeved on the output shaft of the motor, and rolling grooves are respectively provided in the two to play the role of cams. Figure 7 Reference numeral B represents the presser foot lifting cam 50 and the stitch length adjustment cam 201, which are combined into a whole and are sleeved on the output shaft of the motor; and the two act as cams through their outer contours; Figure 7 C, D and E are all combined as a whole and sleeved on the output shaft of the motor. The difference is that some use outer contours and some use rolling grooves, as shown in the figure.

[0042] Example 3

[0043] Preferably, based on the above-mentioned embodiment one, the second transmission assembly includes a stitch length eccentric wheel 206, a stitch length adjustment link 203, a first feed adjustment rod 204, and a second feed adjustment rod 205; the stitch length eccentric wheel 206 is eccentrically connected to the output shaft of the second motor 20; the stitch length eccentric wheel 206 is rotatably connected to the first end of the stitch length adjustment link 203, and the second end of the stitch length adjustment link 203 is hinged to the first end of the first feed adjustment rod 204; the second end of the first feed adjustment rod 204 is hinged to the frame; the middle part of the first feed adjustment rod 204 is connected to the first end of the second feed adjustment rod 205, and the second end of the second feed adjustment rod 205 is hinged to the middle part of the first link 103.

[0044] Preferably, the presser foot lifting cam 50 and the stitch length eccentric wheel 206 are integrally formed and sleeved on the output shaft of the second motor 20, or the presser foot lifting cam 50 and the stitch length eccentric wheel 206 are separately formed and sleeved on the output shaft of the second motor 20 in parallel.

[0045] In specific implementation, the arrangement of the presser foot lifting cam 50 and the stitch length eccentric wheel 206 is similar to the arrangement of the presser foot lifting cam 50 and the stitch length adjustment cam 201 in the second embodiment, and will not be repeated here. Figure 7 Both F and D use the presser foot lifting cam 50 and the stitch length eccentric wheel 206 as a whole and are mounted on the output shaft of the motor. The difference is that the presser foot lifting cam in F uses an outer contour, while the presser foot lifting cam in G uses a rolling groove, as shown in the figure.

[0046] Example 4

[0047] Preferably, based on the above-mentioned embodiment one, the second transmission assembly includes a stitch crank 207, a stitch adjustment link 203, a first feed adjustment rod 204, and a second feed adjustment rod 205; the first end of the stitch crank 207 is fixedly connected to the output shaft of the second motor 20; the stitch crank 207 is rotatably connected to the first end of the stitch adjustment link 203, and the second end of the stitch adjustment link 203 is hinged to the first end of the first feed adjustment rod 204; the second end of the first feed adjustment rod 204 is hinged to the frame; the middle part of the first feed adjustment rod 204 is connected to the first end of the second feed adjustment rod 205, and the second end of the second feed adjustment rod 205 is hinged to the middle part of the first link 103.

[0048] Example 5

[0049] Preferably, based on the above-mentioned embodiments one, two, three and four, the feeding assembly includes a feeding shaft 41, a first slider 42, a second slider 43 and a tooth-lifting rocker arm 44; the feeding shaft 41 is fixedly connected to the first slider 42, and the first slider 42 is provided with a accommodating space 45 for accommodating the second slider 43. When the second slider 43 is located in the accommodating space 45, there is a gap with the first slider 42. The tooth-lifting rocker arm 44 is fixedly connected to the second slider 43, and the tooth-lifting rocker arm 44 is hinged to the frame; when the first motor rotates, the first connecting rod 103 drives the feeding shaft 41 to rotate, thereby driving the tooth-lifting rocker arm 44 to move back and forth to realize feeding.

[0050] Preferably, the second motor 20 is a stepping motor.

[0051] Preferably, if Figure 4 As shown: it also includes a presser foot lifting assembly; the presser foot lifting assembly includes a presser foot lifting cam 50, a presser foot lifting rod 51, a first lever 52, a second lever 53, a connecting plate 54 and a presser foot lifting assembly 55, and the presser foot lifting rod 51 is in contact with the presser foot lifting cam 50; the middle parts of the first lever 51 and the second lever 53 are both hinged to the frame, the presser foot lifting rod 51 is fixedly connected to one end of the first lever 52, the other end of the first lever 52 and the first end of the second lever 53 are respectively hinged to the connecting plate 54, and the second end of the second lever 53 is connected to the presser foot lifting assembly 55; the presser foot lifting cam 50 is connected to the output shaft of the second motor 20.

[0052] Preferably, if Figure 4 As shown, the presser foot lifting assembly 55 includes a pressure rod 56 , and a second end of the second lever 53 is provided with a lap groove, and the pressure rod 56 is lapped on the lap groove of the second lever 53 .

[0053] In specific implementation, a lap groove design is adopted to overlap the pressure rod 56 on the second lever 53, which can facilitate installation and maintenance.

[0054] Preferably, if Figure 4 As shown: the presser foot lifting assembly 55 includes a presser foot 57, and the bottom surface of the presser foot 57 is L-shaped.

[0055] Preferably, if Figure 4 As shown: one end of the presser foot lifting rod 51 is in contact with the presser foot lifting cam 50 through a fisheye joint; the fisheye joint is also connected through a roller 58 and a second connecting rod 59, the fisheye joint is hinged to the roller 58, the roller 58 is fixedly connected to the first end of the second connecting rod 59, and the second end of the second connecting rod 59 is hinged to the second rotating shaft 302 on the frame.

Claims

1. A sewing machine capable of conveniently adjusting the stitch length, characterized in that: It includes a first motor, a second motor, a first transmission assembly, a second transmission assembly and a feeding assembly; the first transmission assembly includes a first connecting rod, the first motor is hinged to the first end of the first connecting rod through a first cam, and the second end of the first connecting rod is connected to the feeding assembly; when the first motor is working, the feeding assembly is driven to work to feed the material through the first connecting rod; the second motor is connected to the first connecting rod through the second transmission assembly, and when the second motor is working, the first connecting rod is changed by a certain angle through the second transmission assembly, so that when the first motor is working, the feeding amplitude of the feeding assembly can be changed to adjust the needle distance.

2. The sewing machine capable of conveniently adjusting stitch length according to claim 1, characterized in that: The first end of the first connecting rod is an opening structure with two parallel sides. The outer circumference of the first cam is a U-shaped groove. The U-shaped groove is provided with a profile that matches the opening structure. The first connecting rod is adaptively connected to the profile.

3. The sewing machine capable of conveniently adjusting stitch length according to claim 1, characterized in that: It also includes a presser foot lifting assembly; the presser foot lifting assembly includes a presser foot lifting cam, a presser foot lifting rod, a first lever, a second lever, a connecting plate and a presser foot lifting rod assembly, the presser foot lifting rod is in contact with the presser foot lifting cam; the middle parts of the first lever and the second lever are both hinged to the frame, the presser foot lifting rod is hinged to one end of the first lever, the other end of the first lever and the first end of the second lever are respectively hinged to the connecting plate, and the second end of the second lever is connected to the presser foot lifting rod assembly; the presser foot lifting cam is connected to the output shaft of the second motor.

4. The sewing machine capable of conveniently adjusting stitch length according to claim 3, characterized in that: The second transmission assembly includes a stitch length adjustment cam, a stitch length adjustment crank, a stitch length adjustment connecting rod, a first feed adjustment rod, and a second feed adjustment rod; the stitch length adjustment cam is connected to the output shaft of the second motor; the first position of the stitch length adjustment crank is hinged to the first rotating shaft on the frame, the second position is a position that can abut the stitch length adjustment cam, and the third position is hinged to the first end of the stitch length adjustment connecting rod, and the first position, the second position and the third position are not on the same straight line; the second end of the stitch length adjustment connecting rod is hinged to the first end of the first feed adjustment rod; the second end of the first feed adjustment rod is hinged to the frame; the middle part of the first feed adjustment rod is connected to the first end of the second feed adjustment rod, and the second end of the second feed adjustment rod is hinged to the middle part of the first connecting rod.

5. The sewing machine capable of conveniently adjusting stitch length according to claim 4, characterized in that: The presser foot lifting cam and the stitch length adjusting cam are sleeved together to form an integral sleeve and are arranged on the output shaft of the second motor, or the presser foot lifting cam and the stitch length adjusting cam are sleeved on the output shaft of the second motor respectively.

6. The sewing machine capable of conveniently adjusting stitch length according to claim 3, characterized in that: The second transmission assembly includes a needle pitch eccentric wheel, a needle pitch adjustment connecting rod, a first feed adjustment rod, and a second feed adjustment rod; the needle pitch eccentric wheel is eccentrically connected to the output shaft of the second motor; the needle pitch eccentric wheel is rotatably connected to the first end of the needle pitch adjustment connecting rod, and the second end of the needle pitch adjustment connecting rod is hinged to the first end of the first feed adjustment rod; the second end of the first feed adjustment rod is hinged to the frame; the middle part of the first feed adjustment rod is connected to the first end of the second feed adjustment rod, and the second end of the second feed adjustment rod is hinged to the middle part of the first connecting rod.

7. The sewing machine capable of conveniently adjusting stitch length according to claim 6, characterized in that: The presser foot lifting cam and the stitch length eccentric wheel are integrally formed and sleeved together to form an integral sleeve and arranged on the output shaft of the second motor, or the presser foot lifting cam and the stitch length eccentric wheel are respectively sleeved on the output shaft of the second motor.

8. The sewing machine capable of conveniently adjusting stitch length according to claim 3, characterized in that: The second transmission assembly includes a stitch length crank, a stitch length adjustment connecting rod, a first feed adjustment rod, and a second feed adjustment rod; the first end of the stitch length crank is fixedly connected to the output shaft of the second motor; the stitch length crank is rotatably connected to the first end of the stitch length adjustment connecting rod, and the second end of the stitch length adjustment connecting rod is hinged to the first end of the first feed adjustment rod; the second end of the first feed adjustment rod is hinged to the frame; the middle part of the first feed adjustment rod is connected to the first end of the second feed adjustment rod, and the second end of the second feed adjustment rod is hinged to the middle part of the first connecting rod.

9. The sewing machine capable of conveniently adjusting stitch length according to claim 1, characterized in that: The feeding assembly includes a feeding shaft, a first slider, a second slider and a tooth-lifting rocker arm; the feeding shaft is fixedly connected to the first slider, and the first slider is provided with an accommodating space for accommodating the second slider. When the second slider is located in the accommodating space, there is a gap between the second slider and the first slider. The tooth-lifting rocker arm is fixedly connected to the second slider, and the tooth-lifting rocker arm is hinged to the frame; when the first motor rotates, the first connecting rod drives the feeding shaft to rotate, thereby driving the tooth-lifting rocker arm to move back and forth to realize feeding.

10. The sewing machine capable of conveniently adjusting stitch length according to any one of claims 1 to 9, characterized in that: It also includes a presser foot lifting assembly; the presser foot lifting assembly includes a presser foot lifting cam, a presser foot lifting rod, a first lever, a second lever, a connecting plate and a presser foot lifting assembly, and the presser foot lifting rod is in contact with the presser foot lifting cam; the middle parts of the first lever and the second lever are hinged to the frame, the presser foot lifting rod is fixedly connected to one end of the first lever, the other end of the first lever and the first end of the second lever are respectively hinged to the connecting plate, and the second end of the second lever is connected to the presser foot lifting assembly; the presser foot lifting cam is connected to the output shaft of the second motor.

11. The sewing machine capable of conveniently adjusting stitch length according to claim 10, characterized in that: The presser foot lifting assembly includes a pressure rod, a second end of the second lever is provided with a lap groove, and the pressure rod is lapped on the lap groove of the second lever.

12. The sewing machine capable of conveniently adjusting stitch length according to claim 11, characterized in that: One end of the presser foot lifting rod is in contact with the presser foot lifting cam through a fisheye joint; the fisheye joint is also connected through a roller and a second connecting rod, the fisheye joint is hinged to the roller, the roller is fixedly connected to the first end of the second connecting rod, and the second end of the second connecting rod is hinged to the second rotating shaft on the frame.

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