Drive mechanism for thread trimming and presser foot lifting in a sewing machine

Abstract

The utility model provides sewing machine's drive mechanism of cutting thread and lifting presser foot belongs to sewing machine technical field. It solved the problem of inconvenient assembly brought by using a drive cam to drive cutting thread and lifting presser foot. It includes drive motor, cutting thread transmission spare, cutting thread transmission structure between cutting thread transmission spare and cutting thread shaft, drive cam and lifting presser foot transmission structure between drive cam edge and presser foot, drive cam edge has idle stroke surface and cam surface in proper order, the side of drive cam projects and sets action part along the axial direction, cutting thread transmission spare is connected on the output shaft of drive motor and is fixed along the axial direction, cutting thread transmission spare and action part abut along the circumference direction, idle stroke surface moves along lifting presser foot transmission structure when drive cam pushes cutting thread transmission spare to swing through action part, action part and cutting thread transmission spare separate along the circumference direction when drive cam drives presser foot to lift through cam surface. It has improved the convenience of assembly and the like advantages.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine technology, and relates to the drive mechanism for cutting thread and lifting presser foot in a sewing machine. Background Technology

[0002] A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on fabric, so that one or more layers of fabric are interwoven or sewn together. Sewing machines are divided into various models according to actual use, but regardless of the model, after sewing is completed, the actions of cutting the thread and lifting the presser foot are required.

[0003] For example, the thread-cutting and presser foot lifting mechanism of the button-attaching machine disclosed in patent application number 202422187797.2 includes a drive motor, a presser foot lifting drive block, a thread-cutting drive block, a thread-cutting blade, and a button clamp block located inside the machine housing. A drive cam is mounted on the output shaft of the drive motor. The presser foot lifting drive block and the thread-cutting drive block are both close to the side of the drive cam. When the drive motor drives the drive cam to rotate, the drive cam sequentially drives the thread-cutting drive block and the presser foot lifting drive block to rotate. The rotating thread-cutting drive block and the presser foot lifting drive block drive the thread-cutting blade and the button clamp block respectively through a linkage. The drive cam rotates in two stages. The wire-cutting drive block is approximately L-shaped, the pressure foot lifting drive block is located below the drive cam, and the wire-cutting drive block is located on the side of the drive cam. The drive cam includes a small-diameter end and a large-diameter end. Both the pressure foot lifting drive block and the wire-cutting drive block are close to the small-diameter end of the drive cam. The center of the small-diameter end coincides with the rotation center of the drive cam, while the center of the large-diameter end is eccentrically set relative to the rotation center of the drive cam. That is, the edge of the drive cam at the small-diameter end is the idle stroke surface, and the edge of the drive cam at the large-diameter end is the cam surface. The drive motor starts and drives the drive cam to rotate. The large-diameter end of the rotating drive cam first contacts the wire-cutting drive block and drives it to rotate to perform the wire-cutting action. After the wire cutting is completed, the drive motor continues to drive the drive cam to rotate until the large-diameter end of the drive cam contacts the pressure foot lifting drive block and drives it to rotate to perform the pressure foot lifting action.

[0004] However, the aforementioned wire-cutting and pressing foot lifting mechanism, through the above-mentioned configuration, enables it to simultaneously drive the pressing foot lifting action using the drive cam and perform the wire-cutting action using the same drive cam. But since both wire cutting and pressing foot lifting are actually accomplished by the edge position of the drive cam wheel, the wire-cutting drive block can only be hinged inside the housing to cooperate with the drive cam. This means that the wire-cutting drive block needs to be installed independently inside the housing, and special attention must be paid to the position of the drive cam during installation to avoid obstructing the installation of the wire-cutting drive block. Therefore, there is a problem of inconvenient assembly. Utility Model Content

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a drive mechanism for thread cutting and presser foot lifting in a sewing machine, thus solving the assembly inconvenience caused by using a single drive cam to drive thread cutting and presser foot lifting.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] A drive mechanism for thread cutting and presser foot lifting in a sewing machine includes a drive motor with an output shaft parallel to the thread cutting shaft, a thread cutting transmission component, a thread cutting transmission structure located between the thread cutting transmission component and the thread cutting shaft, a drive cam fixed on the output shaft of the drive motor, and a presser foot lifting transmission structure located between the edge of the drive cam and the presser foot. The edge of the drive cam has a free travel surface and a cam surface in sequence. The rotation of the drive cam can drive the presser foot lifting transmission structure to lift the presser foot through the cam surface. The key feature is that an action part is provided on one side of the drive cam along the axial direction. The thread cutting transmission component is directly or indirectly sleeved on the output shaft of the drive motor and the two are fixed along the axial direction. The thread cutting transmission component and the action part are located on the same side of the drive cam and abut against each other circumferentially. When the drive cam rotates, it pushes the thread cutting transmission component to swing through the action part. The free travel surface moves along the presser foot lifting transmission structure. When the drive cam rotates, it drives the presser foot to lift through the cam surface. The action part and the thread cutting transmission component separate circumferentially.

[0008] When the sewing machine is in sewing mode, the thread-cutting mechanism inside the machine is not working and the presser foot is in the depressed state. At this time, the presser foot lifting transmission structure abuts against the idle stroke surface of the drive cam near the cam surface, and the actuating part on the drive cam abuts against the thread-cutting transmission component circumferentially. To better understand the rotation direction of the drive motor's output shaft during operation, the counterclockwise rotation direction of the drive motor's output shaft is defined as the thread-cutting direction, and the clockwise rotation direction is defined as the presser foot lifting direction. After sewing is completed, the drive motor's output shaft rotates counterclockwise and, through the abutting part against the thread-cutting transmission component, pushes the thread-cutting transmission component to rotate. In this way, the thread-cutting transmission component drives the thread-cutting shaft to rotate through the thread-cutting transmission structure to perform the thread-cutting action. During the rotation of the thread-cutting transmission component, the idle stroke surface of the drive cam edge moves along the presser foot lifting transmission structure. At this time, the presser foot lifting transmission structure remains stationary, keeping the presser foot in the depressed state. After thread trimming, the output shaft of the drive motor rotates clockwise, causing the drive cam to return to its initial position. The thread trimming transmission component, thread trimming transmission structure, and thread trimming shaft are then reset by the return torsion spring built into the sewing machine. When it is necessary to lift the presser foot, the output shaft of the drive motor rotates clockwise, and the cam surface of the drive cam edge contacts the presser foot lifting transmission structure. As the drive cam continues to rotate, the cam surface drives the presser foot lifting transmission structure to lift the presser foot. During the movement of the cam surface along the presser foot lifting transmission structure, the actuating part and the thread trimming transmission component continuously separate circumferentially. That is, during the presser foot lifting process, the thread trimming transmission component remains stationary, preventing the thread trimming shaft from rotating.

[0009] This drive mechanism features an actuating part protruding axially along the output shaft of the drive motor on one side of the drive cam. This actuating part drives the thread cutter, effectively shifting the thread-cutting position on the drive cam from its edge to one side. This eliminates the need for a separate thread-cutting drive component within the sewing machine. During assembly, the thread-cutting drive component is simply fitted onto the output shaft of the drive motor, ensuring circumferential contact between the component and the actuating part, significantly improving assembly convenience. Furthermore, this structure ensures a more precise fit between the thread-cutting drive component and the drive cam. In existing technologies, the thread-cutting drive block is independently installed within the sewing machine, necessitating strict requirements on its installation position, which can lead to less precise fits in practice.

[0010] In the aforementioned sewing machine, the drive mechanism for thread cutting and presser foot lifting has a cylindrical mounting part protruding from the side of the drive cam. The mounting part and the action part are located on the same side of the drive cam. The central hole of the drive cam passes through the mounting part. The thread cutting transmission component is sleeved on the mounting part. A limit component is fixed on the mounting part. The thread cutting transmission component is axially fixed between the drive cam and the limit component.

[0011] During assembly, the wire-cutting drive component is first fitted onto the cylindrical mounting part, and a limiting component is fixed on the mounting part to axially fix the wire-cutting drive component between the drive cam and the limiting component. This assembles the wire-cutting drive component and the drive cam into a single assembly. Finally, this assembly is fixed to the output shaft of the drive motor through the center hole of the drive cam. This design makes assembly more convenient and, in particular, ensures a high degree of fit between the wire-cutting drive component and the drive cam.

[0012] In the aforementioned sewing machine, the drive mechanism for cutting the thread and lifting the presser foot includes a ring-shaped sleeve and a force-receiving part that protrudes from the outer periphery of the sleeve and is arm-shaped. The thread-cutting drive structure is located between the force-receiving part and the thread-cutting shaft.

[0013] By configuring the thread-cutting drive component as including a ring-shaped sleeve portion and an arm-shaped force-receiving portion protruding from the outer periphery of the sleeve portion, the sleeve portion allows the thread-cutting drive component to be directly or indirectly sleeved on the output shaft of the drive motor, while the arm-shaped force-receiving portion ensures that the thread-cutting drive component can cooperate with the action portion provided on the side of the drive cam, so that the position on the drive cam used for driving the thread cutting can be set on the side of the drive cam, thereby ensuring that the thread-cutting drive component no longer needs to be separately installed in the sewing machine, thus improving the convenience of assembly.

[0014] In the aforementioned sewing machine, the drive mechanism for cutting the thread and lifting the presser foot is columnar, and there is a radial clearance between the drive part and the sleeve part.

[0015] The actuating part is columnar, and the sleeve part is annular with a radial clearance between the actuating part and the sleeve part, so that the actuating part moves around the sleeve part during the separation of the actuating part and avoids interference.

[0016] In the aforementioned sewing machine, the drive mechanism for cutting the thread and lifting the presser foot includes a thread cutting transmission structure comprising a thread cutting transmission crank and a thread cutting connecting rod. The thread cutting transmission crank is fixedly connected to the thread cutting shaft, the lower end of the thread cutting connecting rod is hinged to the thread cutting transmission crank, and the upper end of the thread cutting connecting rod is hinged to the force-bearing part. When the thread cutting transmission component is driven by the drive cam to swing, it will pull the thread cutting connecting rod upward.

[0017] The upper end of the wire-cutting connecting rod is hinged to the force-receiving part, and the lower end of the connecting rod is hinged to the wire-cutting drive crank, which is fixed to the wire-cutting shaft. When the drive cam rotates and pushes the wire-cutting drive component to swing through the abutment between the action part and the force-receiving part, the wire-cutting drive component pulls the connecting rod upward through the force-receiving part. This, in turn, causes the connecting rod to drive the wire-cutting drive crank to swing, thus rotating the wire-cutting shaft and performing the wire-cutting action. This configuration allows the wire-cutting shaft to rotate through a larger angle.

[0018] In the aforementioned sewing machine, the drive mechanism for cutting thread and lifting presser foot includes a guide seat fixed inside the sewing machine body. The presser foot lifting transmission structure includes a drive rod that is slidably mounted on the guide seat in the vertical direction. The drive rod and the presser foot are linked in the vertical direction, and the lower end of the drive rod directly or indirectly abuts against the edge of the drive cam.

[0019] The lower end of the drive rod directly or indirectly abuts against the edge of the drive cam. When the drive cam rotates until its surface abuts against the lower end of the drive rod, it continuously pushes the drive rod upward. Since the drive rod is linked to the presser foot vertically, it also lifts the presser foot upward, thus lifting it. The drive rod is slidably mounted on the guide seat vertically and can only slide up and down, ensuring greater stability when lifting the presser foot.

[0020] In the aforementioned sewing machine, the drive mechanism for thread cutting and presser foot lifting is such that the lower end of the drive rod is rotatably connected to a roller via a fastener. The center line of the roller is parallel to the center line of the drive cam. The bottom of the roller extends beyond the lower end of the drive rod and abuts against the edge of the drive cam. The roller and the thread cutting transmission component are spaced apart along the axial direction.

[0021] A roller is connected to the lower end of the drive rod, and the roller contacts the edge of the drive cam. This creates rolling friction between the roller and the drive cam, which reduces the resistance when the drive rod is lifted and reduces wear during long-term use. The axial spacing between the roller and the wire-cutting drive component ensures that there will be no interference between the drive rod and the wire-cutting drive component under any circumstances, even though the wire-cutting drive component is directly mounted on the output shaft of the drive motor.

[0022] In the aforementioned sewing machine, the drive mechanism for thread cutting and presser foot lifting has a plate-shaped connecting part protruding from the outer periphery of the upper end of the drive rod. The presser foot lifting transmission structure also includes a pull rod and a first swing plate and a second swing plate respectively hinged to the machine body. The two ends of the pull rod are respectively hinged to the first swing plate and the second swing plate. The first swing plate is connected to the connecting part. The hinge point between the first swing plate and the machine body is located along the axial direction of the output shaft of the drive motor between the hinge point between the first swing plate and the connecting part and the hinge point between the first swing plate and the pull rod. A connecting seat is fixed on the presser foot. The second swing plate is hinged to the connecting seat. Under the pull of the pull rod, the second swing plate swings around its hinge point with the machine body and drives the connecting seat to move upward.

[0023] As the drive rod is pushed upward, the connection between the drive rod and the first swing plate will move upward. This means that the hinge point between the first swing plate and the pull rod will move downward. At this time, the first swing plate will pull the second swing plate to swing around its hinge point with the machine body through the pull rod, so that the second swing plate will eventually drive the presser foot to move upward and complete the action of lifting the presser foot.

[0024] In the aforementioned sewing machine, the drive mechanism for cutting thread and lifting presser foot is provided with a connecting hole on the connecting part. The connecting hole is waist-shaped along the axial direction of the output shaft of the drive motor. The first swing plate is connected to the connecting part by a guide pin that passes through the first swing plate and the connecting hole in sequence.

[0025] When the first swing plate swings, the guide pin moves along the connecting hole. This design makes the movement of the drive rod more flexible when it drives the first swing plate to swing, and prevents jamming that would prevent the presser foot from being lifted smoothly.

[0026] Compared with existing technologies, the drive mechanism for thread cutting and presser foot lifting in this sewing machine has an action part protruding along the axial direction of the output shaft of the drive motor on one side of the drive cam. The action part is used to drive the thread cutting, which is equivalent to transferring the position for driving the thread cutting on the drive cam from the edge of the drive cam to one side of the drive cam. This eliminates the need for the thread cutting transmission component to be installed separately in the sewing machine. During assembly, it is only necessary to attach the thread cutting transmission component to the output shaft of the drive motor and ensure that the thread cutting transmission component and the action part abut against each other circumferentially. While using a single drive cam to drive thread cutting and presser foot lifting, it also greatly improves the convenience of assembly. Attached Figure Description

[0027] Figure 1 It is a 3D diagram of a sewing machine.

[0028] Figure 2 This is a three-dimensional diagram of a sewing machine from another angle.

[0029] Figure 3 This is a three-dimensional schematic diagram of the drive mechanism for cutting the thread and lifting the presser foot in this sewing machine.

[0030] Figure 4 This is a schematic diagram showing the interaction between the wire shearing drive component and the drive cam.

[0031] Figure 5 This is an exploded view of the wire shearing drive component and the drive cam.

[0032] Figure 6 It is a planar schematic diagram of the interaction between the drive cam and the drive rod.

[0033] Figure 7 This is a plan view of the thread-cutting and presser foot lifting drive mechanism of this sewing machine in its initial state.

[0034] Figure 8 This is a plan view of the thread-cutting and presser foot lifting drive mechanism of this sewing machine in the thread-cutting state.

[0035] Figure 9 This is a plan view of the thread-cutting and presser foot lifting drive mechanism of this sewing machine when the presser foot is in the lifting state.

[0036] In the diagram, 1. Machine body; 2. Wire cutting shaft; 3. Presser foot; 4. Wire cutting swing arm; 5. Wire cutting swing rod; 6. Wire cutting knife holder; 7. Wire cutting knife; 8. Return torsion spring; 9. Drive motor; 10. Drive cam; 10a. Free stroke surface; 10b. Cam surface; 10c. Actuating part; 10d. Mounting part; 10e. Annular mounting groove; 11. Wire cutting transmission component; 11a. Sleeve part; 11b. Force-bearing part; 12. Limiting component; 13. Wire cutting transmission crank; 14. Wire cutting connecting rod; 15. Guide seat; 16. Drive rod; 16a. Connecting part; 16b. Connecting hole; 17. Roller; 18. Pull rod; 19. First swing plate; 20. Second swing plate; 21. Connecting seat. Detailed Implementation

[0037] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0038] like Figure 1 , Figure 2 and Figure 3 As shown, the sewing machine includes a thread-cutting and presser foot lifting drive mechanism. The sewing machine comprises a body 1, a thread-cutting shaft 2 located at the bottom of the body 1 along its length, a presser foot 3 located at the head of the body 1 in a vertical direction, a thread-cutting swing arm 4 fixed to the thread-cutting shaft 2 at one end of the body 1 corresponding to the head, a thread-cutting swing rod 5 hinged to the thread-cutting swing arm 4, a thread-cutting blade holder 6 hinged to the thread-cutting swing rod 5, a thread-cutting blade 7 fixed to the thread-cutting blade holder 6, a return torsion spring 8 sleeved on the thread-cutting shaft 2, and a return spring (not shown in the figure) sleeved on the presser foot 3 and acting downwards on the presser foot 3. The drive mechanism for cutting the wire and lifting the presser foot includes a drive motor 9, which is fixed to the tail of the machine body 1. The output shaft of the drive motor 9 is located inside the machine body 1 and is parallel to the wire cutting shaft 2. The drive mechanism also includes a wire cutting transmission component 11, a wire cutting transmission structure disposed between the wire cutting transmission component 11 and the wire cutting shaft 2, a drive cam 10 fixed on the output shaft of the drive motor 9, and a presser foot lifting transmission structure disposed between the edge of the drive cam 10 and the presser foot 3.

[0039] like Figure 3 , Figure 4 , Figure 5 and Figure 6As shown, the drive cam 10 has a free stroke surface 10a and a cam surface 10b on its edge. The free stroke surface 10a is an arc surface that is concentric with the output shaft of the drive motor 9. The cam surface 10b is a convex curved surface. One end of the cam surface 10b is connected to the free stroke surface 10a and the two are smoothly connected. The distance from the cam surface 10b to the center line of the output shaft of the drive motor 9 gradually increases from the end connected to the free stroke surface 10a to the other end. The rotation of the drive cam 10 can drive the presser foot 3 to be lifted through the presser foot lifting transmission structure via the cam surface 10b. A working part 10c is provided on one side of the drive cam 10 along the axial direction. The wire cutting transmission component 11 is directly or indirectly sleeved on the output shaft of the drive motor 9 and the two are fixed together along the axial direction. The wire cutting transmission component 11 and the working part 10c are located on the same side of the drive cam 10. The wire cutting transmission component 11 and the working part 10c abut against each other in the circumferential direction. When the drive cam 10 rotates, it pushes the wire cutting transmission component 11 to swing through the working part 10c. The empty stroke surface 10a moves along the lifting pressure foot transmission structure. When the drive cam 10 rotates, it drives the pressure foot 3 to lift through the cam surface 10b. When the working part 10c and the wire cutting transmission component 11 separate in the circumferential direction.

[0040] like Figure 3 , Figure 4 and Figure 5As shown, a cylindrical mounting portion 10d protrudes from the side of the drive cam 10. The mounting portion 10d and the actuating portion 10c are located on the same side of the drive cam 10. The center hole of the drive cam 10 passes through the mounting portion 10d. The wire-cutting transmission component 11 is sleeved on the mounting portion 10d. A limiting component 12 is fixed on the mounting portion 10d. The wire-cutting transmission component 11 is axially fixed between the drive cam 10 and the limiting component 12. Specifically, the mounting portion 10d is provided with an annular mounting groove 10e, and the limiting component 12 is a retaining ring installed in the annular mounting groove 10e. Of course, in addition to a retaining ring, an external thread can also be provided at the end of the mounting portion 10d, and a nut that can be threaded onto the mounting portion 10d can be used as the limiting component 12. During assembly, the sleeve portion 11a of the wire cutting transmission component 11 is first sleeved onto the cylindrical mounting portion 10d, and the limiting member 12 is fixed on the mounting portion 10d to fix the sleeve portion 11a axially between the drive cam 10 and the limiting member 12, so that the wire cutting transmission component 11 and the drive cam 10 are first assembled into a component. Finally, the component is fixed to the output shaft of the drive motor 9 through the center hole of the drive cam 10. The above settings make assembly more convenient, and in particular, can well ensure the fitting accuracy between the wire cutting transmission component 11 and the drive cam 10. The wire cutting transmission component 11 includes an annular sleeve portion 11a and a force-receiving portion 11b protruding from the outer periphery of the sleeve portion 11a and in the shape of an arm. The wire cutting transmission structure is located between the force-receiving portion 11b and the wire cutting shaft 2. The action portion 10c is cylindrical, and there is a radial clearance between the action portion 10c and the sleeve portion 11a. The wire cutting drive structure includes a wire cutting drive crank 13 and a wire cutting connecting rod 14. The wire cutting drive crank 13 is fixedly connected to one end of the wire cutting shaft 2 corresponding to the tail of the machine body 1. The lower end of the wire cutting connecting rod 14 is hinged to the wire cutting drive crank 13, and the upper end of the wire cutting connecting rod 14 is hinged to the force-receiving part 11b. When the wire cutting drive component 11 is driven by the drive cam 10 to swing, it will pull the wire cutting connecting rod 14 upward.

[0041] like Figure 2 , Figure 3 and Figure 6As shown, a guide seat 15 is fixed inside the body 1 of the sewing machine. The presser foot lifting transmission structure includes a drive rod 16 that is slidably mounted on the guide seat 15 in the vertical direction. The drive rod 16 and the presser foot 3 are linked in the vertical direction, that is, they move up and down together. The lower end of the drive rod 16 directly or indirectly abuts against the edge of the drive cam 10. A roller 17 is rotatably connected to the lower end of the drive rod 16 by a fastener. The center line of the roller 17 is parallel to the center line of the drive cam 10. The bottom of the roller 17 extends out of the lower end of the drive rod 16 and abuts against the edge of the drive cam 10. The roller 17 and the thread cutting transmission component 11 are spaced apart along the axial direction of the output shaft of the drive motor 9. In this embodiment, the bottom of the drive rod 16 has a relief groove, and the upper part of the roller 17 is located in the relief groove. The upper end of the drive rod 16 has a plate-shaped connecting part 16a protruding from its outer periphery. The lifting foot transmission structure also includes a pull rod 18 and a first swing plate 19 and a second swing plate 20 respectively hinged in the machine body 1. The two ends of the pull rod 18 are respectively hinged to the first swing plate 19 and the second swing plate 20. The first swing plate 19 is connected to the connecting part 16a. Specifically, the connecting part 16a has a connecting hole 16b, which is waist-shaped along the axial direction of the output shaft of the drive motor 9. The first swing plate 19 is connected to the connecting part 16a. The first swing plate 19 and the connecting part 16a are connected by guide pins that pass through the first swing plate 19 and the connecting hole 16b in sequence. The hinge point of the first swing plate 19 and the body 1 is located along the axial direction of the output shaft of the drive motor 9 between the hinge point of the first swing plate 19 and the connecting part 16a and the hinge point of the first swing plate 19 and the pull rod 18. The pressure foot 3 is fixed with the connecting seat 21. The second swing plate 20 is hinged to the connecting seat 21. Under the pull of the pull rod 18, the second swing plate 20 swings with its hinge point with the body 1 as the center and drives the connecting seat 21 to move upward.

[0042] When the sewing machine is in sewing mode, such as Figure 7As shown, the thread-cutting mechanism is not working and the presser foot 3 is in the pressed-down state. At this time, the roller 17 abuts against the idle stroke surface 10a near the cam surface 10b, and the action part 10c on the drive cam 10 abuts against the force-receiving part 11b of the thread-cutting transmission member 11. To better understand the rotation direction of the output shaft of the drive motor 9 during operation, the following description of the operation is based on the direction shown in the attached figure. After sewing is completed, the output shaft of the drive motor 9 rotates counterclockwise and pushes the thread-cutting transmission member 11 to rotate through the abutment of the action part 10c and the force-receiving part 11b. Since the force-bearing part 11b of the wire-cutting transmission component 11 is hinged to the upper end of the wire-cutting connecting rod 14, and the lower end of the wire-cutting connecting rod 14 is hinged to the wire-cutting transmission crank 13 fixed on the wire-cutting shaft 2, when the wire-cutting transmission component 11 rotates, it will pull the wire-cutting connecting rod 14 upward, which in turn will drive the wire-cutting transmission crank 13 to swing. In this way, the wire-cutting shaft 2 will rotate, causing the wire-cutting swing arm 4 to swing. Then, the wire-cutting swing arm 5 will pull the wire-cutting knife holder 6 to swing, thereby causing the wire-cutting knife 7 fixed on the wire-cutting knife holder 6 to move and cut the wire. This state is as follows: Figure 8 As shown. After the wire cutting is completed, the output shaft of the drive motor 9 rotates clockwise to return to its original position. In this direction, the action part 10c is in front and the force-receiving part 11b is behind. Under the action of the return torsion spring 8, the wire cutting blade 7, the wire cutting swing arm 5, the wire cutting swing arm 4, the wire cutting shaft 2, the wire cutting transmission crank 13, the wire cutting connecting rod 14, and the wire cutting transmission component 11 are reset. During the rotation of the wire cutting transmission component 11, the idle stroke surface 10a of the drive cam 10 moves along the roller 17. At this time, the drive rod 16 remains stationary, keeping the pressure foot 3 in the pressed state. Similarly, after the wire cutting is completed and the reset is finished, the drive cam 10 is back in the position where the roller 17 abuts against the idle stroke surface 10a near the cam surface 10b.

[0043] When the pressure foot needs to be lifted, the output shaft of the drive motor 9 rotates clockwise, and the cam surface 10b on the edge of the drive cam 10 contacts the roller 17. As the drive cam 10 continues to rotate, the cam surface 10b pushes the drive rod 16 upwards via the roller 17. This state is as follows: Figure 9As shown, as the drive rod 16 is pushed upward, the connection between the drive rod 16 and the first swing plate 19 moves upward. This means that the hinge point between the first swing plate 19 and the pull rod 18 moves downward. At this time, the first swing plate 19 pulls the second swing plate 20 around its hinge point with the machine body 1 via the pull rod 18, so that the second swing plate 20 eventually drives the pressure foot 3 to overcome the spring force of the return spring and lift upward. During the process of the roller 17 moving along the cam surface 10b, the action part 10c and the force receiving part 11b continuously separate in the circumferential direction. That is to say, during the process of lifting the pressure foot, the wire cutting transmission component 11 remains stationary, so that the wire cutting blade 7 also remains stationary. When it is no longer necessary to lift the presser foot 3, the output shaft of the drive motor 9 rotates counterclockwise. During this process, the contact position between the roller 17 and the edge of the drive cam 10 continuously moves from the cam surface 10b toward the idle stroke surface 10a, so that the drive rod 16 can continuously move downward under the combined action of gravity and the return spring until the contact position of the two is again at the position on the idle stroke surface 10a near the cam surface 10b. At this time, the drive rod 16 moves down to the initial position, and the presser foot 3 is back in the pressed state.

[0044] This drive mechanism features an actuating part 10c protruding axially from one side of the drive cam 10 along the output shaft of the drive motor 9. The actuating part 10c drives the thread cutter, effectively shifting the thread-cutting position on the drive cam 10 from its edge to one side. This eliminates the need for the thread-cutting transmission component 11 to be separately installed within the sewing machine. During assembly, the thread-cutting transmission component 11 is simply fitted onto the output shaft of the drive motor 9, ensuring that it abuts against the actuating part 10c circumferentially, significantly improving assembly convenience. Furthermore, this structure ensures a more precise fit between the thread-cutting transmission component 11 and the drive cam 10. In existing technologies, because the thread-cutting drive block is independently installed within the sewing machine, strict requirements are placed on its installation position, potentially leading to less precise fits in practice.

[0045] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A drive mechanism for thread cutting and presser foot lifting in a sewing machine, comprising a drive motor (9) with its output shaft parallel to a thread cutting shaft (2), a thread cutting transmission component (11), a thread cutting transmission structure disposed between the thread cutting transmission component (11) and the thread cutting shaft (2), a drive cam (10) fixed on the output shaft of the drive motor (9), and a presser foot lifting transmission structure disposed between the edge of the drive cam (10) and the presser foot (2), wherein the edge of the drive cam (10) has a free stroke surface (10a) and a cam surface (10b) in sequence, and the rotation of the drive cam (10) can drive the presser foot lifting transmission structure to lift the presser foot (2) through the cam surface (10b), characterized in that, The drive cam (10) has an axially protruding part (10c) on one side. The wire cutting transmission member (11) is directly or indirectly sleeved on the output shaft of the drive motor (9) and the two are fixed together axially. The wire cutting transmission member (11) and the part (10c) are located on the same side of the drive cam (10). The wire cutting transmission member (11) and the part (10c) abut against each other circumferentially. When the drive cam (10) rotates and pushes the wire cutting transmission member (11) to swing through the part (10c), the space travel surface (10a) moves along the pressure foot lifting transmission structure. When the drive cam (10) rotates and drives the pressure foot (2) to lift through the cam surface (10b), the part (10c) and the wire cutting transmission member (11) separate circumferentially.

2. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 1, characterized in that The drive cam (10) has a cylindrical mounting part (10d) protruding from its side. The mounting part (10d) and the actuating part (10c) are located on the same side of the drive cam (10). The central hole of the drive cam (10) passes through the mounting part (10d). The wire cutting transmission component (11) is sleeved on the mounting part (10d). The limiting component (12) is fixed on the mounting part (10d). The wire cutting transmission component (11) is fixed axially between the drive cam (10) and the limiting component (12).

3. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 2, wherein, The wire cutting transmission component (11) includes a ring-shaped sleeve portion (11a) and a force-receiving portion (11b) protruding from the outer periphery of the sleeve portion (11a) and in the shape of an arm. The wire cutting transmission structure is located between the force-receiving portion (11b) and the wire cutting shaft (2).

4. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 3, wherein, The function part (10c) is columnar, and there is a radial clearance between the function part (10c) and the sleeve part (11a).

5. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 4, wherein, The wire cutting transmission structure includes a wire cutting transmission crank (13) and a wire cutting connecting rod (14). The wire cutting transmission crank (13) is fixedly connected to the wire cutting shaft (2). The lower end of the wire cutting connecting rod (14) is hinged to the wire cutting transmission crank (13), and the upper end of the wire cutting connecting rod (14) is hinged to the force-receiving part (11b). When the wire cutting transmission component (11) is driven by the drive cam (10) to swing, it will pull the wire cutting connecting rod (14) upward.

6. The driving mechanism for thread cutting and presser foot lifting in a sewing machine as claimed in claim 1 or 2 or 3 or 4 or 5 wherein, The sewing machine body (1) is fixed with a guide seat (15). The presser foot lifting transmission structure includes a drive rod (16) that is slidably arranged on the guide seat (15) in the vertical direction. The drive rod (16) and the presser foot (2) are linked in the vertical direction. The lower end of the drive rod (16) directly or indirectly abuts against the edge of the drive cam (10).

7. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 6, wherein, The lower end of the drive rod (16) is rotatably connected to a roller (17) by a fastener. The center line of the roller (17) is parallel to the center line of the drive cam (10). The bottom of the roller (17) extends out of the lower end of the drive rod (16) and abuts against the edge of the drive cam (10). The roller (17) and the wire cutting transmission component (11) are spaced apart along the axial direction.

8. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 7, wherein, The drive rod (16) has a plate-shaped connecting part (16a) protruding from the outer periphery of its upper end. The lifting foot transmission structure also includes a pull rod (18) and a first swing plate (19) and a second swing plate (20) respectively hinged in the body (1). The two ends of the pull rod (18) are respectively hinged to the first swing plate (19) and the second swing plate (20). The first swing plate (19) is connected to the connecting part (16a). The first swing plate (19) is connected to the body (1). The hinge point is located along the axial direction of the output shaft of the drive motor (9) between the hinge point of the first swing plate (19) and the connecting part (16a) and the hinge point of the first swing plate (19) and the pull rod (18). A connecting seat (21) is fixed on the press foot (2). The second swing plate (20) is hinged to the connecting seat (21). Under the pull of the pull rod (18), the second swing plate (20) swings with its hinge point with the machine body (1) as the center and drives the connecting seat (21) to move upward.

9. The sewing machine thread trimming and presser foot lifting drive mechanism according to claim 8, wherein, The connecting part (16a) is provided with a connecting hole (16b). The connecting hole (16b) is waist-shaped along the axial direction of the output shaft of the drive motor (9). The first swing plate (19) and the connecting part (16a) are connected by a guide pin that passes through the first swing plate (19) and the connecting hole (16b) in sequence.

Images