CN215328686U

CN215328686U - Presser foot mechanism is lifted to sewing machine's trimming

Info

Publication number: CN215328686U
Application number: CN202023019900.0U
Authority: CN
Inventors: 任恩林; 蒋达淼; 杨开胜; 周善足
Original assignee: Taizhou Supu Electromechanical Co ltd
Current assignee: Taizhou Supu Electromechanical Co ltd
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2021-12-28
Anticipated expiration: 2030-12-15

Abstract

The utility model belongs to the technical field of sewing equipment, and relates to a thread cutting and presser foot lifting mechanism of a sewing machine, which solves the problems of low operation stability and the like of the thread cutting and presser foot lifting mechanism of the existing sewing machine. The thread trimming presser foot lifting mechanism comprises a motor fixed on a sewing machine shell, wherein a driving assembly is fixed on an output shaft of the motor, a presser foot lifting driving part and a thread trimming driving part are respectively arranged on the driving assembly, the presser foot lifting driving part is connected with a presser foot lifting device of the sewing machine through a presser foot lifting transmission assembly, and the thread trimming driving part is connected with a thread trimming device of the sewing machine through a thread trimming transmission assembly; the driving component, the presser foot lifting transmission component and the thread trimming transmission component are wheel-shaped and coaxial; the motor rotates forwards, the thread cutting device cuts threads, and the presser foot lifting transmission assembly lifts an idle stroke; the motor rotates reversely, the presser foot lifting device carries out presser foot lifting, and the thread trimming transmission assembly carries out idle stroke. This practicality drives through the motor and realizes the trimming and lift the presser foot, rocking and the noise when can effectively reducing the motion improve operating stability.

Description

Presser foot mechanism is lifted to sewing machine's trimming

Technical Field

The utility model belongs to the technical field of sewing equipment, and relates to a thread cutting and presser foot lifting mechanism of a sewing machine.

Background

The traditional sewing machine mostly adopts the electromagnet as a power source, automatic thread trimming and automatic presser foot lifting are respectively controlled by the electromagnet, the thread trimming is carried out by the telescopic driving thread trimming mechanism of the electromagnet core during thread trimming, and the presser foot lifting mechanism is carried out by the telescopic driving of the electromagnet core during automatic presser foot lifting. However, the above mechanism requires many parts, the electromagnet is used as a driving source, the stroke is not flexible, and large shaking and noise are generated during movement, which causes large noise of the sewing machine and affects the stability of the sewing machine.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a thread cutting and presser foot lifting mechanism of a sewing machine aiming at the problems in the prior art, and the technical problems to be solved by the utility model are as follows: how to improve the stability of this sewing machine's trimming lifts presser foot mechanism during operation.

The purpose of the utility model can be realized by the following technical scheme:

the trimming and presser foot lifting mechanism of the sewing machine is characterized by comprising a motor fixed on a sewing machine shell, wherein a driving assembly is fixed on an output shaft of the motor, a presser foot lifting driving part and a trimming driving part are respectively arranged on the driving assembly, the presser foot lifting driving part is connected with a presser foot lifting device of the sewing machine through a presser foot lifting transmission assembly, and the trimming driving part is connected with a trimming device of the sewing machine through a trimming transmission assembly; the driving assembly, the pressure foot lifting transmission assembly and the trimming transmission assembly are all wheel-shaped, and the pressure foot lifting transmission assembly and the trimming transmission assembly are respectively positioned on two sides of the driving assembly and coaxially arranged; when the motor rotates forwards, the thread trimming device performs thread trimming, and the presser foot lifting transmission assembly performs idle stroke; when the motor rotates reversely, the presser foot lifting device lifts the presser foot, and the trimming transmission assembly executes idle stroke.

The working principle is as follows: when the thread is required to be cut, the motor rotates forwards, the thread cutting device cuts the thread, the presser foot lifting transmission assembly performs idle stroke at the moment, and the presser foot lifting action is not triggered; when the presser foot needs to be lifted, the motor rotates reversely, the presser foot lifting device lifts the presser foot, the thread trimming transmission assembly executes idle stroke at the moment, and thread trimming action is not triggered. This application drives through the motor and realizes the trimming and lift the presser foot, can effectively reduce rocking and the noise when moving, improves operating stability.

In the thread trimming and presser foot lifting mechanism of the sewing machine, the motor is fixed outside the machine shell, and the output shaft extends to the inside of the machine shell. The motor is designed outside the machine shell, the presser foot lifting transmission assembly, the thread trimming transmission assembly and the like are located inside the machine shell, therefore, sufficient lubrication can be carried out on the presser foot lifting transmission assembly, the thread trimming transmission assembly and the like, the motor is located outside the machine shell, an oil circuit system is completely isolated by the motor, lubricating oil can be effectively prevented from entering each motor, the mechanical assembly can work in an internal oil supply system in a wear-resistant mode, and the lubricating performance is guaranteed while the oil-proof performance is improved.

In the sewing machine, the presser foot lifting transmission assembly comprises a presser foot lifting transmission wheel sleeved on the output shaft, the presser foot lifting transmission wheel is in rotating fit with the output shaft, a first connecting part connected with the presser foot lifting device is arranged on the presser foot lifting transmission wheel, an arc-shaped groove I is concentrically arranged on the wheel surface of the presser foot lifting transmission wheel, the presser foot lifting driving part comprises a presser foot lifting driving pin fixed on one side of the driving assembly, and the presser foot lifting driving pin is movably arranged in the arc-shaped groove I. When the presser foot needs to be lifted, the motor rotates reversely to drive the driving assembly on the output shaft to rotate reversely, so that the presser foot lifting driving pin on the driving assembly is driven to move in the first arc-shaped groove, the presser foot lifting driving pin is contacted with one end of the first arc-shaped groove, and the presser foot lifting driving wheel is driven to rotate reversely, so that the presser foot lifting device is driven to lift the presser foot; after the presser foot lifting is finished, the motor rotates forwards to drive the driving assembly and the presser foot lifting driving pin to reset, and the presser foot lifting driving wheel and the presser foot lifting device can reset under the action of a reset piece of the existing presser foot lifting device.

In the sewing machine, the presser foot lifting device comprises a top rod, a rear lever, a pull rod, a front lever, a presser foot lifting plate, a presser foot guide frame, a pressure rod and a presser foot plate, the rear lever and the front lever are both pivoted on the machine shell, the lower end of the top rod is hinged with a connecting part on the presser foot lifting transmission wheel, the upper end of the top rod is hinged with the rear end of the rear lever, the front end of the rear lever is hinged with the rear end of the pull rod, the front end of the pull rod is hinged with one end of the front lever, the other end of the front lever is connected with the presser foot lifting plate, the pressure rod is arranged on the machine shell in a sliding mode, the presser foot guide frame is fixed on the pressure rod and matched with the presser foot lifting plate, and the presser foot plate is fixed at the lower end of the pressure rod. When the presser foot needs to be lifted, the motor drives the output shaft to rotate reversely, so that the presser foot lifting driving pin on the driving assembly is driven to move in the first arc-shaped groove, the presser foot lifting driving pin is made to contact with one end of the first arc-shaped groove, the presser foot lifting driving wheel is driven to rotate reversely, the ejector rod is driven to jack upwards, the front end of the rear lever is driven to pull backwards, the pull rod is made to perform backward pulling action, the other end of the front lever is made to lift upwards, and then the pressure rod moves upwards through the presser foot lifting plate belt, and upward lifting of the presser foot is achieved.

In the sewing machine, the thread trimming transmission assembly comprises a thread trimming transmission wheel sleeved on the output shaft, the thread trimming transmission wheel is in running fit with the output shaft, a second connection part connected with the thread trimming device is arranged on the thread trimming transmission wheel, an arc-shaped groove II is concentrically arranged on the wheel surface of the thread trimming transmission wheel, the thread trimming driving part comprises a thread trimming driving pin fixed on the other side of the driving assembly, and the thread trimming driving pin is movably arranged in the arc-shaped groove II. When the trimming is needed, the motor rotates forwards to drive the driving assembly to rotate forwards so as to drive the trimming driving pin on the driving assembly to move in the second arc-shaped groove, and after the trimming driving pin is contacted with one end of the second arc-shaped groove, the motor continues to rotate to drive the trimming driving wheel to rotate forwards so as to drive the trimming device to perform trimming; after the trimming is finished, the motor rotates reversely to drive the driving assembly and the trimming driving pin to reset, and the trimming driving wheel and the like can reset under the action of a reset piece of the trimming device.

In the sewing machine, the presser foot lifting transmission wheel is concentrically provided with a third arc-shaped groove, the thread cutting transmission wheel is concentrically provided with a fourth arc-shaped groove, the driving assembly is provided with a through hole which can be communicated with the third arc-shaped groove and the fourth arc-shaped groove, a thread cutting forced reset pin is arranged in the through hole in a sliding manner, a spring is arranged between the thread cutting forced reset pin and the driving assembly, and one end of the thread cutting forced reset pin is provided with a guide part matched with the three phases of the arc-shaped grooves; when the sewing machine is in a thread cutting state, the guide part on the thread cutting forced resetting pin is abutted against the inner side of the presser foot lifting transmission wheel, so that the other end of the thread cutting forced resetting pin is inserted into the arc-shaped groove IV; when the sewing machine is in a state that the thread cutting reset is finished, the guide part on the thread cutting forced reset pin slides into the arc-shaped groove III, and the other end of the thread cutting forced reset pin slides out of the arc-shaped groove IV. When the thread trimming is finished and needs to be reset, the other end of the thread trimming forced reset pin can move in the arc-shaped groove IV until the thread trimming forced reset pin is contacted with one end of the arc-shaped groove IV to drive the thread trimming driving wheel to rotate to realize resetting, and after the resetting is finished, the guide part of the thread trimming forced reset pin is aligned with the arc-shaped groove III on the presser foot lifting driving wheel and slides into the arc-shaped groove III again to enable the other end of the thread trimming forced reset pin to slide out of the arc-shaped groove IV.

In the sewing machine, the thread trimming device includes a thread trimming connecting rod, a first thread trimming crank, a thread trimming spool, a second thread trimming crank, a knife rest connecting rod, a knife rest and a thread trimming knife, the upper end of the thread trimming connecting rod is hinged to the connecting portion on the thread trimming driving wheel, the lower end of the thread trimming connecting rod is hinged to one end of the first thread trimming crank, the other end of the first thread trimming crank is fixed to the thread trimming spool, the other end of the thread trimming spool is fixed to one end of the second thread trimming crank, the other end of the second thread trimming crank is hinged to one end of the knife rest connecting rod, the other end of the knife rest connecting rod is hinged to the knife rest, and the thread trimming knife is fixed to the knife rest. When the trimming is needed, the motor rotates positively to drive the driving assembly to rotate positively, so that the trimming driving pin on the driving assembly is driven to move in the second arc-shaped groove, after the trimming driving pin is contacted with one end of the second arc-shaped groove, the motor continues to rotate to drive the trimming driving wheel to rotate positively, so that the trimming connecting rod is driven to swing, the trimming crank drives the trimming shaft to rotate, the rotation of the trimming shaft drives the trimming crank to swing, the tool rest is driven to rotate through the tool rest connecting rod, and finally the trimming knife is driven to move to realize trimming.

In the sewing machine, the driving component is wheel-shaped, and the presser foot lifting transmission wheel and the thread cutting transmission wheel are respectively positioned on two sides of the driving component and coaxially arranged.

Compared with the prior art, the utility model has the following advantages:

the motor design is outside in the casing, lifts presser foot drive assembly and trimming drive assembly etc. and all is located inside the casing, consequently, can carry out sufficient lubrication to lifting presser foot drive assembly and trimming drive assembly etc. and the motor is located the casing outside, can effectively avoid lubricating oil to get into the motor, when guaranteeing this trimming and lifting presser foot mechanism lubricating property, improves grease proofing performance.

Drawings

FIG. 1 is a schematic view of the structure of the sewing machine.

Fig. 2 is a schematic structural view of the presser foot lifting mechanism of the sewing machine.

Fig. 3 is a schematic structural view of the thread trimming mechanism of the sewing machine.

Fig. 4 is a structural schematic diagram of forced resetting of the thread cutting of the sewing machine.

Fig. 5 is an exploded view of the forced resetting of the thread cutting of the sewing machine.

In the figure, 1, a housing; 2. a motor; 3. an output shaft; 4. a drive assembly; 5. a presser foot lifting drive part; 6. a trimming drive section; 7. a presser foot lifting transmission assembly; 8. a trimming transmission assembly; 9. a thread trimming device; 10. a presser foot lifting device; 13. a presser foot lifting transmission wheel; 14. a first arc-shaped groove; 15. a top rod; 16. a rear lever; 17. a pull rod; 18. a front lever; 19. a presser foot lifting plate; 20. a pressure lever; 21. a foot pressing plate; 22. a trimming transmission wheel; 23. an arc-shaped groove III; 24. an arc-shaped groove IV; 25. a through hole; 26. a wire shearing forced reset pin; 27. a spring; 28. a guide portion; 29. trimming connecting rods; 30. a first thread trimming crank; 31. a thread cutting shaft; 32. a second thread trimming crank; 33. a tool rest connecting rod; 34. a tool holder; 35. a thread cutter; 36. And a second arc-shaped groove.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1, 2 and 3, the sewing machine includes a housing 1, a motor 2, a driving assembly 4, a presser foot lifting transmission assembly 7 and a thread cutting transmission assembly 8, wherein the motor 2 is located outside the housing 1, an output shaft 3 of the motor 2 extends to the inside of the housing 1, and the driving assembly 4 is fixed on the output shaft 3 and located inside the housing 1. The distribution of the components is a preferred solution for this embodiment, and those skilled in the art can modify the installation position according to actual needs without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

The driving component 4 is respectively provided with a presser foot lifting driving part 5 and a thread cutting driving part 6, one end of a presser foot lifting transmission component 7 is connected with the presser foot lifting driving part 5, the other end of the presser foot lifting transmission component 7 is connected with a presser foot lifting device 10, one end of a thread cutting transmission component 8 is connected with the thread cutting driving part 6, and the other end of the thread cutting transmission component 8 is connected with a thread cutting device 9; when the motor 2 rotates forwards, the thread trimming device 9 performs thread trimming, and the presser foot lifting transmission assembly 7 performs idle stroke; when the motor 2 rotates forwards, the presser foot lifting device 10 lifts the presser foot, and the trimming transmission assembly 8 executes idle stroke.

Preferably, as shown in fig. 1, in the present embodiment, the motor 2 and the second motor 12 are both located below the spindle motor 11 and distributed around the spindle motor 11.

As shown in fig. 2, specifically, the lifting and pressing foot transmission assembly 7 includes a lifting and pressing foot transmission wheel 13 sleeved on the output shaft 3, the lifting and pressing foot transmission wheel 13 is rotatably matched with the output shaft 3, the lifting and pressing foot transmission wheel 13 is provided with a first connection part connected with the lifting and pressing foot device 10, an arc-shaped groove 14 is concentrically arranged on the wheel surface of the lifting and pressing foot transmission wheel 13, the lifting and pressing foot driving part 5 includes a lifting and pressing foot driving pin fixed on one side of the driving assembly 4, and the lifting and pressing foot driving pin is movably arranged in the arc-shaped groove 14.

In this embodiment, the presser foot lifting device 10 includes a top rod 15, a rear lever 16, a pull rod 17, a front lever 18, a presser foot lifting plate 19, a guide frame of the pressure rod 20, a pressure rod 20 and a presser foot plate 21, the rear lever 16 and the front lever 18 are both pivoted on the housing 1, the lower end of the top rod 15 is hinged to a connecting part on the presser foot lifting transmission wheel 13, the upper end of the top rod 15 is hinged to the rear end of the rear lever 16, the front end of the rear lever 16 is hinged to the rear end of the pull rod 17, the front end of the pull rod 17 is hinged to one end of the front lever 18, the other end of the front lever 18 is connected to the presser foot lifting plate 19, the pressure rod 20 is slidably disposed on the housing 1, the guide frame of the pressure rod 20 is fixed on the pressure rod 20 and is matched with the presser foot lifting plate 19, and the presser foot plate 21 is fixed at the lower end of the pressure rod 20.

It should be noted that, in this embodiment, the lower end of the ejector rod 15 is hinged to the first connecting portion on the lifting and pressing foot driving wheel 13, and the upper end of the ejector rod 15 is hinged to the rear end of the rear lever 16, which can directly adopt the through holes on the ejector rod 15, the first connecting portion on the lifting and pressing foot driving wheel 13, and the rear end of the rear lever 16 to match with each other, and of course, preferably adopt the clearance fit, which can reduce the production cost. Of course, a universal connection can also be adopted, and the cost of the connection mode is higher.

As shown in fig. 3, in this embodiment, the thread trimming transmission assembly 8 includes a thread trimming transmission wheel 22 sleeved on the output shaft 3, the thread trimming transmission wheel 22 is rotatably matched with the output shaft 3, a connection portion two connected with the thread trimming device 9 is provided on the thread trimming transmission wheel 22, an arc-shaped groove two 36 is concentrically formed on a wheel surface of the thread trimming transmission wheel 22, the thread trimming driving portion 6 includes a thread trimming driving pin fixed on the other side of the driving assembly 4, and the thread trimming driving pin is movably disposed in the arc-shaped groove two 36.

In order to avoid the clamping stagnation and prevent the normal reset, as shown in fig. 2, 3 and 4, in this embodiment, an arc-shaped groove three 23 is concentrically formed on the pressure foot lifting transmission wheel 13, an arc-shaped groove four 24 is concentrically formed on the wire cutting transmission wheel 22, a through hole 25 capable of being communicated with the arc-shaped groove three 23 and the arc-shaped groove four 24 is formed on the driving component 4, a wire cutting forced reset pin 26 is slidably arranged in the through hole 25, a spring 27 is arranged between the wire cutting forced reset pin 26 and the driving component 4, and one end of the wire cutting forced reset pin 26 is provided with a guide part 28 matched with the arc-shaped groove three 23; when the sewing machine is in a thread cutting state, the guide part 28 on the thread cutting forced resetting pin 26 is abutted against the inner side of the presser foot lifting transmission wheel 13, so that the other end of the thread cutting forced resetting pin 26 is inserted into the arc-shaped groove four 24; when the sewing machine is in the state that the thread cutting is reset, the guide part 28 on the thread cutting forced reset pin 26 slides into the arc-shaped groove III 23, and the other end on the thread cutting forced reset pin 26 slides out from the arc-shaped groove IV 24.

As shown in fig. 3, in this embodiment, the thread trimming device 9 includes a thread trimming connecting rod 29, a first thread trimming crank 30, a thread trimming spool 31, a second thread trimming crank 32, a first cutter holder 34 connecting rod 33, a cutter holder 34, and a thread trimming cutter 35, an upper end of the thread trimming connecting rod 29 is hinged to the connecting portion two phases on the thread trimming driving wheel 22, a lower end of the thread trimming connecting rod 29 is hinged to one end of the first thread trimming crank 30, the other end of the first thread trimming crank 30 is fixed to the thread trimming spool 31, the other end of the thread trimming spool 31 is fixed to one end of the second cutter holder 32, the other end of the second cutter holder 32 is hinged to one end of the connecting rod 33 of the cutter holder 34, the other end of the connecting rod 33 of the cutter holder 34 is hinged to the cutter holder 34, and the thread trimming cutter 35 is fixed to the cutter holder 34. It should be noted that in this embodiment, the driving assembly 4 is preferably wheel-shaped, and the lifting and pressing foot driving wheel 13 and the trimming driving wheel 22 are respectively located on two sides of the driving assembly 4 and are coaxially disposed. Alternatively, the drive assembly 4 may be designed in other shapes as desired.

The working principle of the utility model is as follows: when the presser foot needs to be lifted, the motor 2 drives the output shaft 3 to rotate reversely, so that the presser foot lifting driving pin on the driving assembly 4 is driven to move in the arc-shaped groove I14, the presser foot lifting driving pin is enabled to be in contact with one end of the arc-shaped groove I14, the presser foot lifting driving wheel 13 is driven to rotate reversely, the ejector rod 15 is driven to jack up upwards, the front end of the rear lever 16 is driven to pull backwards, the pull rod 17 is enabled to perform a backward pulling action, the other end of the front lever 18 is enabled to lift upwards, the press rod 20 is driven to move upwards through the presser foot lifting plate 19, and the presser foot is lifted upwards. After the presser foot lifting is finished, the motor 2 rotates forwards to drive the driving component 4 and the presser foot lifting driving pin to reset, and the presser foot lifting driving wheel 13 and the presser foot lifting device 10 can reset under the action of a reset piece of the existing presser foot lifting device 10.

When the trimming is needed, the motor 2 rotates positively to drive the driving component 4 to rotate positively, so as to drive the trimming driving pin on the driving component 4 to move in the second arc-shaped groove 36, after the trimming driving pin is contacted with one end of the second arc-shaped groove 36, the motor 2 continues to rotate to drive the trimming driving wheel 22 to rotate positively, so as to drive the trimming connecting rod 29 to swing, so as to drive the trimming shaft 31 to rotate through the first trimming crank 30, the trimming shaft 31 rotates to drive the second trimming crank 32 to swing, so as to drive the knife rest 34 to rotate through the knife rest 34 connecting rod 33, and finally drive the trimming knife 35 to move to realize the trimming. After the trimming is finished, the motor 2 rotates reversely to drive the driving component 4 and the trimming driving pin to reset, and the trimming driving wheel 22 and the like can reset under the action of a reset piece of the trimming device 9.

In order to avoid clamping stagnation and incapability of resetting the trimming, when the trimming is finished and needs to be reset, the other end of the trimming forced resetting pin 26 can move in the arc-shaped groove four 24, the trimming forced resetting pin 26 is contacted with one end of the arc-shaped groove four 24 to drive the trimming transmission wheel 22 to rotate to realize resetting, and after the resetting is finished, the guide part 28 of the trimming forced resetting pin 26 is aligned to the arc-shaped groove three 23 on the lifting presser foot transmission wheel 13 and slides into the arc-shaped groove three 23 again, so that the other end of the trimming forced resetting pin 26 slides out of the arc-shaped groove four 24.

The specific embodiments described herein are merely illustrative of the spirit of the utility model. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the utility model as defined in the appended claims.

Claims

1. The trimming and presser foot lifting mechanism of the sewing machine is characterized by comprising a motor (2) fixed on a machine shell (1), wherein a driving component (4) is fixed on an output shaft (3) of the motor (2), a presser foot lifting driving part (5) and a trimming driving part (6) are respectively arranged on the driving component (4), the presser foot lifting driving part (5) is connected with a presser foot lifting device (10) of the sewing machine through a presser foot lifting transmission component (7), and the trimming driving part (6) is connected with a trimming device (9) of the sewing machine through a trimming transmission component (8); the driving component (4), the pressure foot lifting transmission component (7) and the thread cutting transmission component (8) are all wheel-shaped, and the pressure foot lifting transmission component (7) and the thread cutting transmission component (8) are respectively positioned on two sides of the driving component (4) and are coaxially arranged; when the motor (2) rotates positively, the thread trimming device (9) performs thread trimming, and the presser foot lifting transmission assembly (7) performs idle stroke; when the motor (2) rotates reversely, the presser foot lifting device (10) lifts the presser foot, and the trimming transmission assembly (8) executes an idle stroke.

2. The trimming and presser foot lifting mechanism of sewing machine according to claim 1, wherein said motor (2) is fixed to the outside of said housing (1), and said output shaft (3) extends to the inside of said housing (1).

3. The trimming and presser foot lifting mechanism of sewing machine according to claim 1, wherein said presser foot lifting transmission assembly (7) comprises a presser foot lifting transmission wheel (13) sleeved on said output shaft (3), said presser foot lifting transmission wheel (13) is rotatably matched with said output shaft (3), said presser foot lifting transmission wheel (13) is provided with a first connecting part connected with said presser foot lifting device (10), the wheel surface of said presser foot lifting transmission wheel (13) is concentrically provided with a first arc-shaped groove (14), said presser foot lifting driving part (5) comprises a presser foot lifting driving pin fixed on one side of said driving assembly (4), and said presser foot lifting driving pin is movably arranged in said first arc-shaped groove (14).

4. The trimming and presser foot lifting mechanism of sewing machine according to claim 3, wherein said presser foot lifting device (10) comprises a top bar (15), a rear lever (16), a pull bar (17), a front lever (18), a presser foot lifting plate (19), a guide frame of a pressure bar (20), a pressure bar (20) and a presser foot plate (21), said rear lever (16) and said front lever (18) are pivoted on said machine shell (1), the lower end of said top bar (15) is hinged with a connecting part on said presser foot lifting transmission wheel (13), the upper end of said top bar (15) is hinged with the rear end of said rear lever (16), the front end of said rear lever (16) is hinged with the rear end of said pull bar (17), the front end of said pull bar (17) is hinged with one end of said front lever (18), the other end of said front lever (18) is connected with a presser foot lifting plate (19), the pressing rod (20) is arranged on the machine shell (1) in a sliding mode, a guide frame of the pressing rod (20) is fixed on the pressing rod (20) and matched with the presser foot lifting plate (19), and the presser foot plate (21) is fixed at the lower end of the pressing rod (20).

5. The trimming presser foot lifting mechanism of a sewing machine according to claim 3 or 4, wherein the trimming transmission assembly (8) comprises a trimming transmission wheel (22) sleeved on the output shaft (3), the trimming transmission wheel (22) is in running fit with the output shaft (3), a second connecting part connected with the trimming device (9) is arranged on the trimming transmission wheel (22), an arc-shaped groove (36) is concentrically arranged on the wheel surface of the trimming transmission wheel (22), the trimming driving part (6) comprises a trimming driving pin fixed on the other side of the driving assembly (4), and the trimming driving pin is movably arranged in the arc-shaped groove (36).

6. The trimming presser foot lifting mechanism of a sewing machine according to claim 5, wherein the trimming presser foot lifting transmission wheel (13) is concentrically provided with a third arc-shaped groove (23), the trimming transmission wheel (22) is concentrically provided with a fourth arc-shaped groove (24), the driving assembly (4) is provided with a through hole (25) capable of being communicated with the third arc-shaped groove (23) and the fourth arc-shaped groove (24), a trimming forced reset pin (26) is slidably arranged in the through hole (25), a spring (27) is arranged between the trimming forced reset pin (26) and the driving assembly (4), and one end of the trimming forced reset pin (26) is provided with a guide part (28) matched with the third arc-shaped groove (23); when the sewing machine is in a thread cutting state, a guide part (28) on the thread cutting forced resetting pin (26) is abutted against the inner side of the presser foot lifting transmission wheel (13), so that the other end of the thread cutting forced resetting pin (26) is inserted into the arc-shaped groove (24); when the sewing machine is in a state that the thread cutting reset is finished, the guide part (28) on the thread cutting forced reset pin (26) slides into the arc-shaped groove III (23), and the other end of the thread cutting forced reset pin (26) slides out of the arc-shaped groove IV (24).

7. The trimming presser foot lifting mechanism of sewing machine according to claim 5, wherein the trimming device (9) comprises a trimming connecting rod (29), a trimming crank I (30), a trimming shaft (31), a trimming crank II (32), a tool holder (34) connecting rod (33), a tool holder (34) and a trimming knife (35), the upper end of the trimming connecting rod (29) is hinged with the connecting part on the trimming driving wheel (22), the lower end of the trimming connecting rod (29) is hinged with one end of the trimming crank I (30), the other end of the trimming crank I (30) is fixed on the trimming shaft (31), the other end of the trimming shaft (31) is fixed with one end of the trimming crank II (32), the other end of the trimming crank II (32) is hinged with one end of the tool holder (34) connecting rod (33), and the other end of the tool holder (34) connecting rod (33) is hinged with the tool holder (34), the thread trimmer (35) is fixed on the tool rest (34).