A driving device for thread cutting, presser foot lifting and lowering, and stitch length adjustment

Abstract

The present invention provides a driving device for thread cutting, presser foot lifting and needle pitch adjustment, belonging to the technical field of sewing machines. It solves the problems such as reduced working efficiency of the existing device when meeting the requirements of driving thread cutting, presser foot lifting and needle pitch adjustment by one motor. The driving device for thread cutting, presser foot lifting and needle pitch adjustment includes a motor. A separately arranged thread cutting cam, a presser foot lifting cam and a needle pitch adjusting cam are fixedly connected to the rotating shaft of the motor. Both the thread cutting cam and the presser foot lifting cam are diamond-shaped, and the needle pitch adjusting cam is a curved quadrilateral. The needle pitch adjusting mechanism abuts against the outer peripheral wall of the needle pitch adjusting cam. When the effective needle pitch adjusting section of the needle pitch adjusting cam acts on the needle pitch adjusting mechanism, the thread cutting idle stroke surface of the thread cutting cam acts on the thread cutting mechanism, and the lifting idle stroke surface of the presser foot lifting cam acts on the presser foot lifting mechanism. This device meets the requirements of driving thread cutting, presser foot lifting and needle pitch adjustment by one motor and improves the working efficiency of the sewing machine at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewing machines and relates to a driving device for thread cutting, presser foot lifting and stitch length adjustment. Background Art

[0002] A sewing machine is a machine that stitches sewing materials through sewing threads. A sewing machine includes a needle bar mechanism, a thread take-up mechanism, a feeding mechanism, a looper mechanism, a pressing mechanism, a presser foot lifting mechanism, a stitch length adjustment mechanism, a thread cutting mechanism, etc. With the development of automation, these mechanisms have been gradually improved and equipped with driving parts, and the driving parts include motors, electromagnets, cylinders, oil cylinders, etc. When the stitch length in the stitch length adjustment mechanism is adjusted to a negative value, the sewing machine realizes reverse sewing.

[0003] For example, a sewing machine controlled by three stepping motors disclosed in Chinese patent literature [Application No.: CN201921700559.X; Publication No.: 210975093U] drives the thread cutting mechanism, the presser foot lifting mechanism and the reverse sewing mechanism respectively through three motors. Driving the three mechanisms respectively by three motors can ensure the execution efficiency of the actions, but the three motors have a high cost and will occupy a large space of the sewing machine. In order to reduce costs and streamline the structure, one motor is often used to drive multiple mechanisms. For example, the presser foot lifting mechanism, the stitch length adjustment mechanism and the thread cutting mechanism are driven by one motor. For example, a sewing machine thread cutting, presser foot lifting and stitch length adjusting device disclosed in Chinese patent literature [Application No.: CN201910098254.4; Publication No.: 111501216A] includes a power member, a first cam, a second cam, a thread cutting drive crank, a presser foot lifting drive crank and a stitch length adjusting drive crank. Both the first cam and the second cam are connected to the power member and rotate under the drive of the power member. The first cam has a thread cutting profile surface, and a thread cutting ball on the thread cutting drive crank cooperates with the thread cutting profile surface. The second cam has a presser foot lifting profile surface, and a presser foot ball on the presser foot lifting drive crank cooperates with the presser foot lifting profile surface. The second cam also has a stitch length adjusting profile surface, and a stitch length adjusting ball on the stitch length adjusting drive crank cooperates with the stitch length adjusting profile surface.

[0004] In the above-mentioned thread cutting, presser foot lifting and stitch length adjusting device, the first cam and the thread cutting drive crank cooperate to realize thread cutting. The structure adopted by the first cam is not only complex but also can only realize unidirectional rotation for thread cutting. The first cam must rotate to make the thread cutting ball abut against the starting end of the thread cutting segment before thread cutting, which will reduce the execution efficiency of the thread cutting action and thus reduce the working efficiency of the sewing machine. In addition, there is also only one place for presser foot lifting and one place for stitch length adjustment within one circumference on the second cam. When the presser foot lifting action and the stitch length adjustment action are required, the required position needs to be found on one circumference, which will reduce the execution efficiency of the presser foot lifting action and the stitch length adjustment and thus reduce the working efficiency of the sewing machine. Summary of the Invention

[0005] The object of the present invention is to address the above problems existing in the prior art, and a driving device for thread cutting, presser foot lifting and stitch length adjustment is proposed, which solves the technical problem that the working efficiency of a sewing machine is reduced when an existing device satisfies the requirements of driving thread cutting, presser foot lifting and stitch length adjustment with one motor.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A driving device for thread cutting, presser foot lifting and stitch length adjustment is installed on a sewing machine. The sewing machine includes a thread cutting mechanism, a presser foot lifting mechanism and a stitch length adjustment mechanism. The driving device for thread cutting, presser foot lifting and stitch length adjustment includes a motor. A thread cutting cam for driving the thread cutting mechanism, a presser foot lifting cam for driving the presser foot lifting mechanism and a stitch length adjustment cam for driving the stitch length adjustment mechanism are fixedly connected to the rotating shaft of the motor. It is characterized in that the thread cutting cam, the presser foot lifting cam and the stitch length adjustment cam are separately arranged. The thread cutting cam and the presser foot lifting cam are both diamond-shaped. The centers of the thread cutting cam and the presser foot lifting cam are fixed on the motor rotating shaft. The outer peripheral wall of the thread cutting cam includes two spaced-apart thread cutting idle stroke surfaces. The outer peripheral wall of the presser foot lifting cam includes two spaced-apart lifting idle stroke surfaces. The stitch length adjustment cam is a curved quadrilateral. The outer peripheral wall of the stitch length adjustment cam includes two oppositely arranged swinging idle stroke surfaces and two oppositely arranged swinging working surfaces. The swinging idle stroke surfaces are convex arc surfaces. The two swinging idle stroke surfaces are on the same circumference and are concentric with the motor rotating shaft. The swinging working surfaces are concave arc surfaces. A swinging ejector rod is fixedly connected to the stitch length adjustment mechanism. The swinging ejector rod abuts against the outer peripheral wall of the stitch length adjustment cam. The swinging working surface includes an effective stitch length adjustment section. When the effective stitch length adjustment section acts on the swinging ejector rod, the thread cutting idle stroke surface acts on the thread cutting mechanism and the lifting idle stroke surface acts on the presser foot lifting mechanism.

[0008] When the motor rotating shaft rotates, the thread cutting cam, the presser foot lifting cam and the stitch length adjustment cam rotate synchronously. The thread cutting action of the thread cutting mechanism includes thread cutting when the moving knife moves to the cutting edge of the fixed knife and the reset of the moving knife away from the fixed knife after thread cutting. Since the thread cutting cam is diamond-shaped and has two spaced-apart thread cutting idle stroke surfaces, and the diamond structure is a central symmetric structure and an axisymmetric structure, the thread cutting cam can drive the thread cutting mechanism to perform two intermittent thread cutting actions whether it rotates forward one week or backward one week. Moreover, the thread cutting performed during forward rotation is reset during reverse rotation, and the reset performed during forward rotation is thread cut during reverse rotation. When the thread cutting idle stroke surface acts on the thread cutting mechanism during forward and reverse rotations, the thread cutting mechanism cannot be driven to act. Therefore, when the motor needs to drive for thread cutting, it can quickly rotate to the appropriate position nearby by forward or reverse rotation, improving the execution efficiency of thread cutting and thus the working efficiency of the sewing machine.

[0009] The presser foot lifting and lowering actions of the presser foot mechanism include the lifting process and the lowering process. Since the presser foot cam is diamond-shaped and has two spaced lifting idle stroke surfaces, and the diamond structure is a centrally symmetric structure and an axially symmetric structure, the presser foot cam can drive the presser foot mechanism to perform two intermittent presser foot actions whether it rotates forward one week or backward one week. Moreover, when it rotates forward, the part that lifts will lower when it rotates backward, and the part that lowers when it rotates forward will lift when it rotates backward. When the lifting idle stroke surface acts on the presser foot mechanism during forward and backward rotations, it cannot drive the presser foot mechanism to act. Therefore, when the motor needs to drive the presser foot to lift or lower, it can quickly rotate to the appropriate position by rotating forward or backward, which can also improve the execution efficiency of the presser foot operation, thus improving the working efficiency of the sewing machine.

[0010] For the stitch length adjusting cam, since the stitch length adjusting cam is a curvilinear quadrilateral, the outer peripheral wall of the stitch length adjusting cam includes two oppositely arranged swinging working surfaces, and the swinging idle stroke surface is a convex circular arc surface. The two swinging idle stroke surfaces are on the same circumference and are concentrically arranged with the motor shaft, that is, the distances from all positions in the circumferential direction of the swinging idle stroke surface to the center of the shaft are the same. In this way, when the swinging push rod moves on the swinging idle stroke surface, the stitch length adjusting mechanism does not move; the outer peripheral wall of the stitch length adjusting cam also includes two oppositely arranged swinging working surfaces, and the swinging working surface is a concave circular arc surface, that is, the distance from the swinging working surface to the center of the shaft is less than the distance from the swinging idle stroke surface to the center of the shaft. In this way, when the swinging push rod moves on the swinging working surface, the stitch length adjusting mechanism will act. And since the swinging working surface is a circular arc structure, the distances from all positions in the circumferential direction of the swinging working surface to the center of the shaft change continuously along the circumferential direction. As the stitch length adjusting cam rotates, the amount of movement change of the stitch length adjusting mechanism changes continuously, so that the size of the stitch length changes continuously, making the stitch length continuously adjustable. Therefore, when the stitch length adjusting cam rotates continuously for one week, two continuous adjustments of the stitch length can be made. Whether it rotates forward or backward, the required stitch length value can be found on the swinging working surface. When the rotation reaches the appropriate position and the motor stops working, sewing can be performed at this stitch length value. In this way, when the motor needs to drive the stitch length adjustment, it can quickly rotate to the appropriate position by rotating forward or backward, improving the execution efficiency of the stitch length adjustment, thus improving the working efficiency of the sewing machine.

[0011] Meanwhile, since the thread cutting cam in a rhombus structure can make the thread cutting mechanism perform two thread cutting actions intermittently during one rotation, that is, there is a thread cutting idle stroke surface on the thread cutting cam to make the thread cutting mechanism inoperative between the two thread cutting actions. Similarly, there is a lifting idle stroke surface on the presser foot lifting cam to make the presser foot lifting mechanism inoperative between the two presser foot lifting actions. When installing the thread cutting cam, the presser foot lifting cam, and the stitch length adjusting cam on the rotating shaft of the motor, by utilizing the characteristics of the rhombus structure of the thread cutting cam and the presser foot lifting cam, and the characteristics of the curvilinear quadrilateral structure of the stitch length adjusting cam, and the fact that the thread cutting cam, the presser foot lifting cam, and the stitch length adjusting cam are separately fixed on the motor rotating shaft, a suitable position can be found in the relative circumferential angular relationship among the thread cutting cam, the presser foot lifting cam, and the stitch length adjusting cam, so that an effective stitch length adjusting section is obtained on the swinging working surface. When the effective stitch length adjusting section acts on the swinging ejector rod, the thread cutting idle stroke surface acts on the thread cutting mechanism and the lifting idle stroke surface acts on the presser foot lifting mechanism, that is, when the motor drives the stitch length adjusting mechanism to adjust the stitch length, both the thread cutting mechanism and the presser foot lifting mechanism are inoperative, thus meeting the requirement of driving the thread cutting, presser foot lifting, and stitch length adjusting of the sewing machine by one motor.

[0012] Therefore, this device meets the requirements of driving the thread cutting, presser foot lifting, and stitch length adjusting of the sewing machine by one motor while improving the working efficiency of the sewing machine. The structures of the thread cutting cam, the presser foot lifting cam, and the stitch length adjusting cam are simple, which simplifies the structure of the sewing machine and makes it convenient to install this device on the sewing machine. And the motor rotating shaft can achieve two thread cutting actions, two presser foot lifting actions, and two stitch length adjustments in one rotation, which also expands the application range of this device.

[0013] In the above-mentioned driving device for thread cutting, presser foot lifting, and stitch length adjusting, the two swinging working surfaces are symmetric about the center of the rotating shaft, and the two swinging idle stroke surfaces are symmetric about the center of the rotating shaft.

[0014] In this way, the stitch length adjusting cam can make the stitch length adjusting mechanism reciprocate once every half rotation, and the movement processes of the stitch length adjusting mechanism in the two half rotations within one circumference are exactly the same, which can keep the stitch length adjustment consistent in the two half rotations, ensure the interchangeability between the two half rotations, is beneficial to expanding the application range and improving the universality of installation, also improves the execution efficiency of stitch length adjustment and the working efficiency of the sewing machine, and makes the sewing thread trace of the sewing machine stable and accurate.

[0015] In the above-mentioned driving device for thread cutting, presser foot lifting, and stitch length adjusting, a first transition fillet surface and a second transition fillet surface are respectively arranged between the swinging working surface and the two adjacent swinging idle stroke surfaces. The two first transition fillets are symmetric about the center of the rotating shaft, and the two second transition fillet surfaces are symmetric about the center of the rotating shaft.

[0016] The settings of the first transition rounded corner surface and the second transition rounded corner surface enable the swing ejector rod to move stably when switching and transitioning between the swing working surface and the swing idle stroke surface, avoiding jamming and affecting the operation of the entire device. The two first transition rounded corners are symmetric about the axis center, and the two second transition rounded corner surfaces are symmetric about the axis center, which can keep the stitch pitch adjustment consistent within two half-cycles, ensuring the interchangeability between the two half-cycles, facilitating the improvement of the usage range and the universality of installation, enhancing the execution efficiency of the stitch pitch adjustment and the working efficiency of the sewing machine, and also making the sewing thread trace of the sewing machine stable and accurate.

[0017] In the above-mentioned driving device for thread cutting, presser foot lifting, and stitch pitch adjustment, the radius of the rounded corner of the first transition rounded corner surface is smaller than that of the second transition rounded corner surface, and the first transition rounded corner surface is located within the effective stitch pitch adjustment section.

[0018] This can distinguish the effective stitch pitch adjustment section, facilitating the correspondence of the relative circumferential angle relationship among the thread cutting cam, the presser foot lifting cam, and the stitch pitch adjustment cam. At the same time, it ensures the length of the effective stitch pitch adjustment section, facilitating the adjustment of the stitch pitch.

[0019] In the above-mentioned driving device for thread cutting, presser foot lifting, and stitch pitch adjustment, the outer peripheral wall of the thread cutting cam further includes two symmetrically arranged thread cutting working surfaces, which are respectively connected between two thread cutting idle stroke surfaces. The thread cutting idle stroke surfaces are outwardly convex arc surfaces. The two thread cutting idle stroke surfaces are located on the same circumference and are concentric with the motor rotating shaft. The two thread cutting working surfaces protrude outside the circumference where the thread cutting idle stroke surfaces are located. The thread cutting working surface includes two inclined thread cutting working segments with opposite inclined directions and a thread cutting arc transition segment connecting the two thread cutting working segments.

[0020] The thread cutting mechanism includes a thread cutting crank, and one end of the thread cutting crank abuts against the outer peripheral wall of the thread cutting cam. When the thread cutting cam rotates, when the thread cutting crank abuts against the thread cutting idle stroke surface, since the thread cutting idle stroke surface is an outwardly convex arc surface, the two thread cutting idle stroke surfaces are located on the same circumference and are concentric with the motor rotating shaft, the thread cutting mechanism does not operate. When the thread cutting crank abuts against the thread cutting working surface, since there are two inclined thread cutting working segments with opposite inclined directions on the thread cutting working surface, when the thread cutting cam rotates one week forward or one week backward, the thread cutting crank can achieve two reciprocating swings, that is, two thread cutting actions. And the two thread cutting working surfaces are respectively connected between the two thread cutting idle stroke surfaces. Therefore, the thread cutting cam can drive the thread cutting mechanism to perform two thread cutting actions intermittently during the continuous rotation of one week, which can improve the execution efficiency of the thread cutting action and the working efficiency of the sewing machine. The setting of the thread cutting arc transition segment enables a smooth transition between thread cutting and resetting, making the thread cutting action stable.

[0021] In the above driving device for thread cutting, presser foot lifting and stitch length adjustment, the outer peripheral wall of the presser foot lifting cam further includes two symmetrically arranged lifting working surfaces, which are respectively connected between two lifting idle stroke surfaces. The lifting idle stroke surfaces are outwardly convex arc surfaces. The two lifting idle stroke surfaces are located on the same circumference and are concentrically arranged with the motor rotating shaft. The two lifting working surfaces protrude outside the circumference where the lifting idle stroke surfaces are located. The lifting working surface includes two inclined lifting working segments with opposite inclined directions and a lifting arc transition segment connected between the two lifting working segments.

[0022] The presser foot lifting mechanism includes a lifting ejector rod, and one end of the lifting ejector rod abuts against the outer peripheral wall of the presser foot lifting cam. When the presser foot lifting cam rotates, when the lifting ejector rod abuts against the lifting idle stroke surface, since the lifting idle stroke surface is an outwardly convex arc surface, and the two lifting idle stroke surfaces are located on the same circumference and are concentrically arranged with the motor rotating shaft, the presser foot lifting mechanism does not act. When the lifting ejector rod abuts against the lifting working surface, since there are two inclined lifting working segments with opposite inclined directions on the lifting working surface, when the presser foot lifting cam rotates forward or backward one week, the lifting ejector rod can achieve two reciprocating lifts, that is, two presser foot lifting actions. And the two lifting working surfaces are respectively connected between the two lifting idle stroke surfaces. Therefore, during the continuous rotation of the presser foot lifting cam for one week, it can drive the presser foot lifting mechanism to intermittently perform two presser foot lifting actions, ensuring that the execution efficiency of the presser foot lifting can be improved and the sewing efficiency of the sewing machine can be improved. The setting of the lifting arc transition segment enables a smooth transition between the presser foot rising and the presser foot falling, and enables the presser foot lifting action to be stable.

[0023] In the above driving device for thread cutting, presser foot lifting and stitch length adjustment, the swing working surface further includes an ineffective stitch length adjustment segment other than the effective stitch length adjustment segment; when the most convex point of the thread cutting arc transition segment acts on the thread cutting mechanism, the ineffective stitch length adjustment segment acts on the swing ejector rod, and the middle area of the lifting working segment acts on the presser foot lifting mechanism; when the most convex point of the lifting arc transition segment acts on the presser foot lifting mechanism, the ineffective stitch length adjustment segment acts on the swing ejector rod, and the middle area of the thread cutting working segment acts on the thread cutting mechanism.

[0024] During the rotation of the motor shaft, when the acting point of the swing push rod and the stitch length adjustment cam moves from the effective stitch length adjustment section to the ineffective stitch length adjustment section, the acting point between the outer peripheral wall of the thread cutting cam and the thread cutting mechanism can pass from the thread cutting idle stroke surface through the thread cutting working section and reach the most convex point of the thread cutting arc transition section. The acting point between the outer peripheral wall of the presser foot lifting cam and the presser foot lifting mechanism enters the middle area of the presser foot lifting working section from the lifting idle stroke surface. At this time, the thread cutting in the thread cutting action is completed, but the thread cutting reset has not been carried out. In the presser foot lifting action, the presser foot has not been completely lifted. Then, when the motor continues to rotate in the same direction, the thread cutting action is reset, the presser foot is lifted to the highest position and then lowered. When the motor rotates in the reverse direction, the thread cutting action is reset, the presser foot continues to press the sewing material, and the stitch length adjustment mechanism performs the effective stitch length adjustment action. Similarly, after the presser foot lifting action is completed, the reverse rotation is used for thread cutting and thread cutting reset, and the forward rotation is used for effective stitch length adjustment; when sewing is finished, the motor rotates forward for first thread cutting and then presser foot lifting, and the motor rotates in the reverse direction for first presser foot lifting and then thread cutting. Therefore, the above-mentioned thread cutting cam, presser foot lifting cam and stitch length adjustment cam can well realize the functions of driving thread cutting, presser foot lifting and stitch length adjustment by one motor, and can complete the required actions nearby, improving the execution efficiency of the actions and the working efficiency of the sewing machine.

[0025] In the above-mentioned driving device for thread cutting, presser foot lifting and stitch length adjustment, a rotatable stitch length adjustment roller is arranged on the swing push rod. The stitch length adjustment roller abuts against the outer peripheral wall of the stitch length adjustment cam and can roll along the outer peripheral wall of the stitch length adjustment cam. The presser foot lifting mechanism includes a lifting push rod. An installation seat is fixed at the lower end of the lifting push rod. A rotatable presser foot lifting roller is connected to the installation seat. The presser foot lifting roller abuts against the outer peripheral wall of the presser foot lifting cam and can roll along the outer peripheral wall of the presser foot lifting cam.

[0026] The setting of the stitch length adjustment roller makes the movement of the swing push rod smooth on the outer peripheral wall of the stitch length adjustment cam, ensuring the stability of the operation of this device. The setting of the presser foot lifting roller makes the movement of the lifting push rod smooth on the outer peripheral wall of the presser foot lifting cam, ensuring the stability of the operation of this device. And the lifting push rod directly abuts against the outer peripheral wall of the presser foot lifting cam through the presser foot lifting roller, simplifying the installation structure and making the installation of this device convenient on the sewing machine.

[0027] In the above-mentioned driving device for thread cutting, presser foot lifting and stitch length adjustment, the stitch length adjustment mechanism includes a rotatable swing plate seat connected to the sewing machine base. The swing push rod is fixedly connected to the swing plate seat. A support seat is fixedly connected to the sewing machine base. The rotating shaft of the motor is supported on the support seat. A holding spring is fixedly connected between the swing plate seat and the support seat to keep the swing push rod abutting against the stitch length adjustment cam.

[0028] The support base has a supporting effect on the rotating shaft, enabling the rotating shaft to rotate stably, which is beneficial to ensuring the stability of the operation of this device. The retaining spring has a resetting effect, ensuring that the swing ejector rod always abuts against the outer peripheral wall of the stitch length adjusting cam during one rotation of the stitch length adjusting cam, thereby ensuring the stitch length adjusting effect of this device.

[0029] In the above-mentioned driving device for thread cutting, presser foot lifting, and stitch length adjustment, a fixing plate is provided on the upper end of the swing ejector rod, and the fixing plate abuts against and is fixed to the lower surface of the swing plate seat. Fixing the swing ejector rod through the fixing plate makes it convenient to fix the swing ejector rod.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The unique structures of the thread cutting cam, presser foot lifting cam, and stitch length adjusting cam and their positional cooperation enable this device to improve the working efficiency of the sewing machine while meeting the requirements of driving the sewing machine for thread cutting, presser foot lifting, and stitch length adjustment by one motor.

[0032] 2. The combined use of the thread cutting cam, presser foot lifting cam, and stitch length adjusting cam can generate more usage combinations, increasing the applicable range of this device and also improving the versatility of this device.

[0033] 3. The settings of the stitch length adjusting roller and the presser foot lifting roller, as well as the settings of the first transition rounded surface, the second transition rounded surface, the lifting arc transition section, and the thread cutting arc transition section, enable this device to operate smoothly.

[0034] 4. The swing ejector rod is fixed to the swing plate seat through the fixing plate, which is convenient for installation.

[0035] 5. The setting of the support base enables the motor to operate stably. Description of the Drawings

[0036] Figure 1 is a perspective view of the first embodiment of this device when installed on a sewing machine [base hidden];

[0037] Figure 2 is a perspective view of the cooperation between the thread cutting cam and the thread cutting mechanism in the first embodiment of this device;

[0038] Figure 3 is a perspective view of the cooperation between the presser foot lifting cam and the lifting ejector rod in the first embodiment of this device;

[0039] Figure 4 is a perspective view of the cooperation between the stitch length adjusting cam and the swing ejector rod in the first embodiment of this device;

[0040] Figure 5 is a front view of the thread cutting cam in the first embodiment of this device;

[0041] Figure 6It is the front view of the presser foot lifting cam in the first embodiment of the present device;

[0042] Figure 7 It is the front view of the stitch length adjusting cam in the first embodiment of the present device;

[0043] Figure 8 It is a schematic diagram of the positional relationship among the thread cutting cam, the presser foot lifting cam, and the stitch length adjusting cam on the circumference of the motor rotating shaft in the first embodiment of the present device;

[0044] Figure 9 It is a three-dimensional view of the first embodiment of the present device when installed on a sewing machine [base not hidden].

[0045] In the figure, 1. Thread cutting mechanism; 1a. Thread cutting drive shaft; 1b. Thread cutting crank; 1b1. Thread cutting convex column; 1c. Thread cutting drive crank; 2. Presser foot lifting mechanism; 2a. Lifting ejector rod; 2a1. Mounting seat; 2a2. Presser foot lifting roller; 2b. Presser foot lever; 2c. Lifting return spring; 3. Stitch length adjusting mechanism; 3a. Swing plate seat; 3a1. Fixed pin; 3b. Rotating shaft; 3c. Holding spring; 4. Motor; 4a. Rotating shaft; 5. Thread cutting cam; 5a1. Thread cutting working surface; 5a11. Thread cutting working section; 5a12. Thread cutting arc transition section; 5a2. Thread cutting idle stroke surface; 5b. Mounting hole 1; 6. Presser foot lifting cam; 6a1. Lifting working surface; 6a11. Lifting working section; 6a12. Lifting arc transition section; 6a2. Lifting idle stroke surface; 6b. Mounting hole 2; 7. Stitch length adjusting cam; 7a1. Swing working surface; 7a11. Effective stitch length adjusting section; 7a12. Ineffective stitch length adjusting section; 7a2. Swing idle stroke surface; 7a3. First transition fillet surface; 7a4. Second transition fillet surface; 7b. Mounting hole 3; 8. Swing ejector rod; 8a. Stitch length adjusting roller; 8b. Fixed plate; 9. Support seat; 10. Mounting plate; 11. Base. Detailed implementation manners

[0046] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0047] Embodiment 1

[0048] As Figure 1 and Figure 9As shown, a driving and adjusting device for thread cutting, presser foot lifting and stitch pitch is installed on a sewing machine. The sewing machine includes a thread cutting mechanism 1, a presser foot lifting mechanism 2 and a stitch pitch adjusting mechanism 3. The driving device for thread cutting, presser foot lifting and stitch pitch adjustment includes a motor 4 fixedly connected to the sewing machine. The motor 4 has a rotating shaft 4a, and the motor 4 also has an encoder capable of controlling the rotation angle of the rotating shaft 4a. In this embodiment, the motor 4 is a double-headed motor. A thread cutting cam 5 for driving the thread cutting mechanism 1 to act, a presser foot lifting cam 6 for driving the presser foot lifting mechanism 2 to act, and a stitch pitch adjusting cam 7 for driving the stitch pitch adjusting mechanism 3 to act are fixedly connected to the rotating shaft 4a. An installation plate 10 is fixed on the motor 4, and the motor 4 is fixedly connected to the base 11 of the sewing machine through the installation plate 10. The thread cutting cam 5 is fixed on the left end of the rotating shaft 4a, the presser foot lifting cam 6 and the stitch pitch adjusting cam 7 are separately fixed on the right end of the rotating shaft 4a, and the stitch pitch adjusting cam 7 is located on the right side of the presser foot lifting cam 6. A first support hole is provided on the base 11, and a first support bearing is installed in the first support hole. The rotating shaft 4a passes through and is fixed in the first support bearing. A support seat 9 is fixedly connected to the base 11 of the sewing machine. A second support hole is provided on the support seat 9, and a second support bearing is fixed in the second support hole. The rotating shaft 4a passes through and is fixed in the second support bearing. The second support bearing is located between the presser foot lifting cam 6 and the stitch pitch adjusting cam 7.

[0049] As Figure 1 , Figure 2 , Figure 5 and Figure 9As shown, the thread cutting mechanism 1 is an existing mechanism of the sewing machine, including a thread cutting drive shaft 1a. A thread cutting crank 1b is fixedly connected to the right end of the thread cutting drive shaft 1a, and a thread cutting drive crank 1c is fixedly connected to the left end of the thread cutting drive shaft 1a. The thread cutting drive crank 1c is connected to a moving knife through a thread cutting assembly. A thread cutting return spring (not shown in the figure) is also provided on the thread cutting drive shaft 1a. A protruding thread cutting stud 1b1 is provided on the movable end of the thread cutting crank 1b. A fixed knife cooperating with the moving knife is fixed on the base 11 of the sewing machine. The thread cutting action of the thread cutting mechanism 1 includes thread cutting when the moving knife moves to the edge of the fixed knife blade and the return of the moving knife away from the fixed knife after thread cutting. The thread cutting cam 5 is rhomboid. The outer peripheral wall of the thread cutting cam 5 abuts against the thread cutting stud 1b1. A thread cutting roller can also be installed on the thread cutting stud 1b1, and the outer peripheral wall of the thread cutting cam 5 abuts against the thread cutting roller. The center of the thread cutting cam 5 is fixed on the rotating shaft 4a of the motor 4. There is a mounting hole 5b at the center of the thread cutting cam 5, and the rotating shaft 4a is inserted into the mounting hole 5b and fixed. The outer peripheral wall of the thread cutting cam 5 can drive the thread cutting mechanism 1 to perform two intermittent thread cutting actions during one continuous rotation of the rotating shaft 4a of the motor 4. The outer peripheral wall of the thread cutting cam 5 includes two symmetrically arranged thread cutting idle stroke surfaces 5a2 and two symmetrically arranged thread cutting working surfaces 5a1. The two thread cutting working surfaces 5a1 are respectively connected between the two thread cutting idle stroke surfaces 5a2. The thread cutting idle stroke surface 5a2 is an outwardly convex arc surface. The two thread cutting idle stroke surfaces 5a2 are located on the same circumference and are concentric with the rotating shaft 4a of the motor 4. The two thread cutting working surfaces 5a1 protrude outside the circumference where the thread cutting idle stroke surface 5a2 is located. The thread cutting working surface 5a1 is V-shaped, including two thread cutting working sections 5a11 and a thread cutting arc transition section 5a12 connecting between the two thread cutting working sections 5a11. The two thread cutting working sections 5a11 are inclined and the inclination directions are opposite. The four thread cutting working sections 5a11 are the four opposite sides of the rhomboid structure of the thread cutting cam 5. Under the action of the thread cutting return spring, the thread cutting stud 1b1 keeps abutting against the outer peripheral wall of the thread cutting cam 5.

[0050] When the thread cutting cam 5 rotates, whether it rotates forward or backward, when the thread cutting convex post 1b1 abuts against the thread cutting idle stroke surface 5a2, the thread cutting cam 5 cannot drive the thread cutting crank 1b to swing, and the moving knife remains stationary at a position away from the fixed knife; when the thread cutting convex post 1b1 abuts against the thread cutting working section 5a11, if the thread cutting convex post 1b1 moves from the thread cutting idle stroke surface 5a2 to the thread cutting arc transition section 5a12, the moving knife moves and approaches the fixed knife. When the thread cutting convex post 1b1 moves to the most convex point of the thread cutting arc transition section 5a12, the moving knife reaches the cutting edge of the fixed knife to complete thread cutting; when the thread cutting convex post 1b1 abuts against the thread cutting working section 5a11, if the thread cutting convex post 1b1 moves from the thread cutting arc transition section 5a12 to the thread cutting idle stroke surface 5a2, the moving knife moves and moves away from the fixed knife, that is, the reset action after thread cutting is performed. Different rotation angles and rotation directions of the rotating shaft 4a correspond to different positions and change trends of the thread cutting convex post 1b1 on the thread cutting surface, so that the moving knife is in different states and movement trends. Therefore, by controlling the rotation angle of the rotating shaft 4a, the thread cutting action can be controlled. Since the thread cutting cam 5 is diamond-shaped, and the diamond structure is a central symmetric structure and an axisymmetric structure, the thread cutting cam 5 can drive the thread cutting mechanism 1 to perform two intermittent thread cutting actions whether it rotates forward one week or backward one week. Moreover, the thread cutting is performed during forward rotation and the reset is performed during reverse rotation, and the reset is performed during forward rotation and the thread cutting is performed during reverse rotation. At the same time, the thread cutting working surface 5a1 is symmetrically arranged on the circumference. Therefore, when the motor 4 needs to drive for thread cutting, it can be quickly rotated to the appropriate position by forward rotation or reverse rotation, improving the execution efficiency of thread cutting and thus improving the working efficiency of the sewing machine.

[0051] Such as Figure 1 , Figure 3 , Figure 6 and Figure 9As shown in the figure, the presser foot lifting mechanism 2 includes a lifting push rod 2a and a presser foot rod 2b. A connecting component is provided between the lifting push rod 2a and the presser foot rod 2b. A lifting return spring 2c is provided on the presser foot rod 2b, and a presser foot is fixedly connected to the lower end of the presser foot rod 2b. An installation seat 2a1 is fixed to the lower end of the lifting push rod 2a, and a rotatable presser foot lifting roller 2a2 is connected to the installation seat 2a1. The presser foot lifting cam 6 is rhombic. The presser foot lifting roller 2a2 abuts against the outer peripheral wall of the presser foot lifting cam 6 and can roll along the outer peripheral wall of the presser foot lifting cam 6. Alternatively, the lower end of the lifting push rod 2a can be directly abutted against the outer peripheral wall of the outer shaft of the presser foot lifting cam 6. The center of the presser foot lifting cam 6 is fixed on the rotating shaft 4a of the motor 4. There is an installation hole two 6b at the center of the presser foot lifting cam 6, and the rotating shaft 4a is inserted into the installation hole two 6b and fixed. The outer peripheral wall of the presser foot lifting cam 6 can drive the presser foot lifting mechanism 2 to perform two intermittent presser foot lifting actions during one continuous rotation of the rotating shaft 4a of the motor 4. The outer peripheral wall of the presser foot lifting cam 6 includes two symmetrically arranged lifting idle stroke surfaces 6a2 and two symmetrically arranged lifting working surfaces 6a1. The two lifting working surfaces 6a1 are respectively connected between the two lifting idle stroke surfaces 6a2. The lifting idle stroke surface 6a2 is an outwardly convex arc surface. The two lifting idle stroke surfaces 6a2 are located on the same circumference and are concentric with the rotating shaft 4a of the motor 4. The two lifting working surfaces 6a1 protrude outside the circumference where the lifting idle stroke surface 6a2 is located. The lifting working surface 6a1 is V-shaped, including two lifting working sections 6a11 and a lifting arc transition section 6a12 connected between the two lifting working sections 6a11. The two lifting working sections 6a11 are inclined and the inclination directions are opposite. The four lifting working sections 6a11 are the four opposite sides of the rhombic structure of the presser foot lifting cam 6. Under the action of the lifting return spring 2c, the presser foot lifting roller 2a2 remains in contact with the outer peripheral wall of the presser foot lifting cam 6.

[0052] When the presser foot lifting cam 6 rotates, whether it rotates forward or backward, when the presser foot lifting roller 2a2 abuts against the lifting idle stroke surface 6a2, the presser foot lifting cam 6 cannot drive the lifting ejector rod 2a to lift or lower, and the presser foot remains in the lowered state without moving; when the presser foot lifting roller 2a2 abuts against the lifting working section 6a11, if the presser foot lifting roller 2a2 moves from the lifting idle stroke surface 6a2 to the lifting arc transition section 6a12, first the lifting return spring 2c is compressed, the pressing force of the presser foot on the sewing material decreases, and then the presser foot is lifted. When the presser foot lifting roller 2a2 moves to the most convex point of the lifting arc transition section 6a12, the presser foot is lifted to the highest position; when the presser foot lifting roller 2a2 abuts against the lifting working section 6a11, if the presser foot lifting roller 2a2 moves from the lifting arc transition section 6a12 to the lifting idle stroke surface 6a2, the presser foot descends and gradually presses tightly on the sewing material. Different rotation angles and rotation directions of the rotating shaft 4a correspond to different positions and changing trends of the presser foot lifting roller 2a2 against the driving surface, so that the presser foot is in different states and movement trends. Therefore, by controlling the rotation angle of the rotating shaft 4a, the lifting control of the presser foot can be achieved. Since the presser foot lifting cam 6 is diamond-shaped, and the diamond structure is a centrosymmetric structure and an axisymmetric structure, the presser foot lifting cam 6 can drive the presser foot mechanism 2 to perform two intermittent presser foot lifting actions whether it rotates forward one week or backward one week. Moreover, the one that is lifted during forward rotation is lowered during reverse rotation, and the one that is lowered during forward rotation is lifted during reverse rotation. At the same time, the lifting working surfaces 6a1 for performing the two presser foot lifting actions on the presser foot lifting cam 6 are symmetrically arranged on the circumference. Therefore, when the motor 4 needs to drive the presser foot to lift, it can be quickly rotated to the appropriate position by forward or reverse rotation nearby, which can also improve the execution efficiency of the presser foot lifting, thereby improving the working efficiency of the sewing machine.

[0053] Such as Figure 1 , Figure 4 , Figure 7 and Figure 9As shown, the stitch pitch adjusting mechanism 3 includes a swing plate seat 3a. A rotating shaft 3b is fixed on the swing plate seat 3a. The rotating shaft 3b is inserted into the base 11 of the sewing machine and can rotate. The swing plate seat 3a has a fixed pin 3a1, and a holding spring 3c is connected to the fixed pin 3a1. A swing ejector rod 8 is fixedly connected to the swing plate seat 3a. The upper end of the swing ejector rod 8 has a fixing plate 8b, and the fixing plate 8b abuts against and is fixed on the lower surface of the swing plate seat 3a. A rotatable stitch pitch adjusting roller 8a is provided at the lower end of the swing ejector rod 8. The stitch pitch adjusting roller 8a abuts against the outer peripheral wall of the stitch pitch adjusting cam 7 and can roll along the outer peripheral wall of the stitch pitch adjusting cam 7. The stitch pitch adjusting cam 7 is a curvilinear quadrilateral. The center of the stitch pitch adjusting cam 7 is fixed on the rotating shaft 4a of the motor 4. An installation hole three 7b is provided at the center of the stitch pitch adjusting cam 7, and the rotating shaft 4a is inserted into the installation hole three 7b and fixed. The outer peripheral wall of the stitch pitch adjusting cam 7 includes two relatively arranged swing idle stroke surfaces 7a2 and two relatively arranged swing working surfaces 7a1. The two swing working surfaces 7a1 are centrosymmetric about the center of the rotating shaft 4a. The two swing idle stroke surfaces 7a2 are centrosymmetric about the center of the rotating shaft 4a. The swing idle stroke surface 7a2 is a convex arc surface. The two swing idle stroke surfaces 7a2 are on the same circumference and are concentric with the rotating shaft 4a of the motor 4. The swing working surface 7a1 is a concave arc surface. First transition fillet surfaces 7a3 and second transition fillet surfaces 7a4 are respectively provided between the swing working surface 7a1 and the two adjacent swing idle stroke surfaces 7a2. The two first transitions are centrosymmetric about the center of the rotating shaft 4a. The two second transition fillet surfaces 7a4 are centrosymmetric about the center of the rotating shaft 4a. The swing working surface 7a1 includes an effective stitch pitch adjustment section 7a11 and an ineffective stitch pitch adjustment section 7a12. When the stitch pitch adjusting roller 8a moves on the effective stitch pitch adjustment section 7a11, the thread cutting convex column 1b1 abuts against and moves on the thread cutting idle stroke surface 5a2, and the presser foot lifting roller 2a2 abuts against and moves on the lifting idle stroke surface 6a2, that is, neither the thread cutting mechanism 1 nor the presser foot lifting mechanism 2 operates. When the stitch pitch adjusting roller 8a moves on the ineffective stitch pitch adjustment section 7a12, the thread cutting mechanism 1 and / or the presser foot lifting mechanism 2 operates. It can also be said that when the effective stitch pitch adjustment section 7a11 acts on the stitch pitch adjusting roller 8a, the thread cutting idle stroke surface 5a2 acts on the thread cutting convex column 1a1, and the lifting idle stroke surface 6a2 acts on the presser foot lifting roller 2a2; when the thread cutting working surface 5a1 acts on the thread cutting convex column 1a1, the ineffective stitch pitch adjustment section 7a12 section or the swing idle stroke section 7a2 acts on the stitch pitch adjusting roller 8a; when the presser foot lifting working surface 6a1 acts on the presser foot lifting roller 2a2, the ineffective stitch pitch adjustment section 7a12 section or the swing idle stroke section 7a2 acts on the stitch pitch adjusting roller 8a. The fillet radius of the first transition fillet surface 7a3 is smaller than the fillet radius of the second transition fillet surface 7a4. The first transition fillet surface 7a3 is located within the effective stitch pitch adjustment section 7a11, and the second transition fillet surface 7a4 is located within the ineffective stitch pitch adjustment section 7a12.The holding spring 3c is fixed between the swing plate seat 3a and the support seat 9, enabling the swing ejector rod 8 to remain in contact with the outer peripheral wall of the stitch regulating cam 7. The holding spring 3c is a tension spring. One end of the holding spring 3c is fixed on the fixed pin 3a1 of the swing plate seat 3a, and the other end of the holding spring 3c is fixed on the support seat 9.

[0054] During the rotation of the stitch regulating cam 7, if the stitch regulating roller 8a abuts against the swing idle stroke surface 7a2, the stitch regulating cam 7 cannot drive the swing plate seat 3a to rotate around the rotation shaft 3b, and the stitch state remains unchanged; when the stitch regulating roller 8a moves on the swing working surface 7a1, the swing plate seat 3a will rotate. Different deflection angles of the swing plate seat 3a correspond to different stitch lengths. When the stitch length is a positive number, forward sewing can be achieved, and when the stitch length is a negative number, reverse sewing can be achieved. Since the passing of the stitch regulating roller 8a on the swing working surface 7a1 is a continuous change process, that is, the stitch length is a continuous change process, the adjustment of the stitch length and the control of reverse sewing can be achieved by controlling the rotation angle of the rotating shaft 4a. However, since the passing of the stitch regulating roller 8a through the ineffective stitch regulating section 7a12 will cause the action of the thread cutting mechanism 1 or / and the presser foot lifting mechanism 2, during sewing, the stitch length is only adjusted within the effective stitch regulating section 7a11. When the stitch regulating cam 7 rotates continuously for one week, two continuous adjustments of the stitch length can be made. Whether rotating forward or backward, the required stitch length value can be found on the swing working surface 7a1. When the rotation reaches the position, the motor 4 stops working and sewing can be carried out with this stitch length value. In this way, when the motor 4 needs to drive for stitch length adjustment, it can quickly rotate to the position nearby by rotating forward or backward, improving the execution efficiency of stitch length adjustment and thus the working efficiency of the sewing machine.

[0055] Such as Figures 1 - 9As shown in the figure, in order to achieve a stable sewing operation, in an ideal state, when the thread cutting stud 1b1 abuts against the thread cutting working surface 5a1, the presser foot lifting roller 2a2 of the lifting ejector rod 2a abuts against the lifting idle stroke surface 6a2, and the stitch regulating roller 8a of the swing ejector rod 8 abuts against the swing idle stroke surface 7a2 or the ineffective stitch regulating section 7a12. That is, when the thread cutting mechanism 1 operates, the presser foot lifting mechanism 2 does not operate, and the stitch regulating mechanism 3 does not perform an effective stitch regulating operation; when the presser foot lifting roller 2a2 of the lifting ejector rod 2a abuts against the lifting working surface 6a1, the thread cutting stud 1b1 abuts against the thread cutting idle stroke surface 5a2, and the stitch regulating roller 8a of the swing ejector rod 8 abuts against the swing idle stroke surface 7a2 or the ineffective stitch regulating section 7a12. That is, when the presser foot lifting mechanism 2 operates, the thread cutting mechanism 1 does not operate, and the stitch regulating mechanism 3 does not perform an effective stitch regulating operation; when the stitch regulating roller 8a of the swing ejector rod 8 abuts against the effective stitch regulating section 7a11, the thread cutting stud 1b1 abuts against the thread cutting idle stroke surface 5a2, and the presser foot lifting roller 2a2 of the lifting ejector rod 2a abuts against the lifting idle stroke surface 6a2. That is, when the stitch regulating mechanism 3 performs an effective stitch regulating operation, the thread cutting mechanism 1 and the presser foot lifting mechanism 2 do not operate. Of course, without affecting the normal operation of the sewing machine, the operations of the thread cutting mechanism 1 and the presser foot lifting mechanism 2 can partially overlap, but the operations of the thread cutting mechanism 1 and the presser foot lifting mechanism 2 cannot enter the effective stitch regulating operation. As Figure 8 shown in the figure, when the most convex point of the thread cutting arc transition section 5a12 acts on the thread cutting mechanism 1, the ineffective stitch regulating section 7a12 acts on the stitch regulating roller 8a, and the middle area of the lifting working section 6a11 acts on the presser foot lifting roller 2a2; when the most convex point of the lifting arc transition section 6a12 acts on the presser foot lifting roller 2a2, the ineffective stitch regulating section 7a12 acts on the stitch regulating roller 8a, and the middle area of the thread cutting working section 5a11 acts on the thread cutting stud 1b1. By using the structural characteristics of the thread cutting cam 5, the presser foot lifting cam 6, and the stitch regulating cam 7, the circumferential positions of the thread cutting cam 5, the presser foot lifting cam 6, and the stitch regulating cam 7 can be adjusted on the rotating shaft 4a, or / and the acting points of the thread cutting cam 5 and the thread cutting stud 1b1, the acting points of the presser foot lifting cam 6 and the presser foot lifting roller 2a2, the acting points of the stitch regulating cam 7 and the stitch regulating roller 8a can be adjusted, or / and the ratios of the thread cutting working surface 5a1 to the thread cutting idle stroke surface 5a2 on the circumference, the ratios of the lifting working surface 6a1 to the lifting idle stroke surface 6a2 on the circumference, and the ratios of the effective stitch regulating section 7a11 to the ineffective stitch regulating section 7a12 on the circumference can be adjusted to meet the above-mentioned ideal state or non-ideal state action requirements. Due to the structural characteristics of the thread cutting cam 5, the presser foot lifting cam 6, and the stitch regulating cam 7, and their circumferential position relationships on the rotating shaft 4a of the motor 4, such as Figure 8, when the thread cutting is completed, the rotating shaft 4a can achieve thread cutting reset both in forward rotation and reverse rotation. After the thread cutting reset, continuing to rotate forward can perform the presser foot lifting action, and continuing to rotate in reverse can perform the stitch length adjustment. Similarly, after the presser foot is lifted, the rotating shaft 4a can achieve presser foot reset both in forward rotation and reverse rotation. After the presser foot reset, continuing to rotate forward can perform the stitch length adjustment, and continuing to rotate in reverse can perform the thread cutting action; after sewing is completed, the rotating shaft 4a can perform the thread cutting action in forward rotation, and the rotating shaft 4a can perform the presser foot lifting action in reverse rotation. When the rotating shaft 4a rotates one week, the thread cutting action, the presser foot lifting action and the stitch length adjustment can be cycled in sequence twice. The coordinated use of the thread cutting cam 5, the presser foot lifting cam 6 and the stitch length adjustment cam 7 enables the required actions to quickly rotate in place nearby, further improving the execution efficiency of the actions. Therefore, this device satisfies the requirement of using one motor 4 to control thread cutting, presser foot lifting and stitch length adjustment simultaneously, improves the working efficiency of the sewing machine, increases the applicable range of this device, and also improves the versatility of this device.

[0056] When installing this device in a sewing machine, since the outer peripheral wall of the presser foot lifting cam 6 directly abuts against the presser foot roller 2a2 of the lifting and lowering ejector rod 2a, and the swing ejector rod 8 directly abutting against the stitch length adjustment cam 7 is fixed on the swing plate seat 3a, there is no need to set other additional matching structures on the base 11 of the sewing machine, so that some old models can also be applicable to this device during the upgrading process, improving the versatility of this device in the installation of the sewing machine, and also being able to reduce the structures and components in new models, simplifying the structure of the sewing machine and making the assembly and debugging of the sewing machine convenient and fast.

[0057] Embodiment 2

[0058] The structure of the swing ejector rod 8 is slightly different from that of Embodiment 1, and other structures are the same as those of Embodiment 1. The swing ejector rod 8 is in a shape of a straight bar. The swing ejector rod 8 is sleeved on the fixing pin 3a1 of the swing plate seat 3a and fixedly connected by screws. The screws pass through the swing ejector rod 8 and are threadedly connected to the fixing pin 3a1.

[0059] Embodiment 3

[0060] The structure of the motor 4 is slightly different from that of Embodiment 1. The motor 4 is a single-head motor 4. The thread cutting cam 5, the presser foot lifting cam 6 and the stitch length adjustment cam 7 are fixedly separated from left to right on the rotating shaft 4a, and the length of the thread cutting drive shaft 1b is appropriately extended to the right. Other structures are the same as those of Embodiment 1.

[0061] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A driving device for thread cutting, presser foot lifting and stitch length adjustment, which is installed on a sewing machine. The sewing machine includes a thread cutting mechanism (1), a presser foot lifting mechanism (2) and a stitch length adjustment mechanism (3). The driving device for thread cutting, presser foot lifting and stitch length adjustment includes a motor (4). A thread cutting cam (5) for driving the thread cutting mechanism (1), a presser foot lifting cam (6) for driving the presser foot lifting mechanism (2) and a stitch length adjusting cam (7) for driving the stitch length adjustment mechanism (3) are fixedly connected to the rotating shaft (4a) of the motor (4). It is characterized in that the thread cutting cam (5), the presser foot lifting cam (6) and the stitch length adjusting cam (7) are separately arranged. The thread cutting cam (5) and the presser foot lifting cam (6) are both diamond-shaped. The centers of the thread cutting cam (5) and the presser foot lifting cam (6) are fixed on the rotating shaft (4a) of the motor (4). The outer peripheral wall of the thread cutting cam (5) includes two spaced thread cutting idle stroke surfaces (5a2). The outer peripheral wall of the presser foot lifting cam (6) includes two spaced lifting idle stroke surfaces (6a2). The stitch length adjusting cam (7) is a curved quadrilateral. The outer peripheral wall of the stitch length adjusting cam (7) includes two relatively arranged swing idle stroke surfaces (7a2) and two relatively arranged swing working surfaces (7a1). The swing idle stroke surfaces (7a2) are convex arc surfaces. The two swing idle stroke surfaces (7a2) are on the same circumference and are concentric with the rotating shaft (4a) of the motor (4). The swing working surfaces (7a1) are concave arc surfaces. A swing ejector rod (8) is fixedly connected to the stitch length adjustment mechanism (3). The swing ejector rod (8) abuts against the outer peripheral wall of the stitch length adjusting cam (7). The swing working surface (7a1) includes an effective stitch length adjustment section (7a11). When the effective stitch length adjustment section (7a11) acts on the swing ejector rod (8), the thread cutting idle stroke surface (5a2) acts on the thread cutting mechanism (1) and the lifting idle stroke surface (6a2) acts on the presser foot lifting mechanism (2).

2. The driving device for thread cutting, presser foot lifting and stitch length adjustment according to claim 1, It is characterized in that the two swing working surfaces (7a1) are centrosymmetric about the center of the rotating shaft (4a), and the two swing idle stroke surfaces (7a2) are centrosymmetric about the center of the rotating shaft (4a).

3. The driving device for thread cutting, presser foot lifting and stitch length adjustment according to claim 2, It is characterized in that a first transition fillet surface (7a3) and a second transition fillet surface (7a4) are respectively arranged between the swing working surface (7a1) and the adjacent two swing idle stroke surfaces (7a2). The two first transition fillets are centrosymmetric about the center of the rotating shaft (4a), and the two second transition fillet surfaces (7a4) are centrosymmetric about the center of the rotating shaft (4a).

4. The driving device for thread cutting, presser foot lifting and stitch length adjustment according to claim 3, It is characterized in that the fillet radius of the first transition fillet surface (7a3) is smaller than the fillet radius of the second transition fillet surface (7a4), and the first transition fillet surface (7a3) is located within the effective stitch length adjustment section (7a11).

5. The driving device for wire cutting, presser foot lifting and stitch length adjustment according to any one of claims 1-4, characterized in that, the outer peripheral wall of the wire cutting cam (5) further includes two symmetrically arranged wire cutting working surfaces (5a1), the two wire cutting working surfaces (5a1) are respectively connected between two wire cutting idle stroke surfaces (5a2), the wire cutting idle stroke surfaces (5a2) are arc surfaces protruding outward, the two wire cutting idle stroke surfaces (5a2) are located on the same circumference and are concentric with the rotating shaft (4a) of the motor (4), the two wire cutting working surfaces (5a1) protrude outside the circumference where the wire cutting idle stroke surfaces (5a2) are located, and the wire cutting working surface (5a1) includes two wire cutting working segments (5a11) arranged obliquely and in opposite directions and a wire cutting arc transition segment (5a12) connected between the two wire cutting working segments (5a11).

6. The driving device for wire cutting, presser foot lifting and stitch length adjustment according to claim 5, characterized in that, the outer peripheral wall of the presser foot lifting cam (6) further includes two symmetrically arranged lifting working surfaces (6a1), the two lifting working surfaces (6a1) are respectively connected between two lifting idle stroke surfaces (6a2), the lifting idle stroke surfaces (6a2) are arc surfaces protruding outward, the two lifting idle stroke surfaces (6a2) are located on the same circumference and are concentric with the rotating shaft (4a) of the motor (4), the two lifting working surfaces (6a1) protrude outside the circumference where the lifting idle stroke surfaces (6a2) are located, and the lifting working surface (6a1) includes two lifting working segments (6a11) arranged obliquely and in opposite directions and a lifting arc transition segment (6a12) connected between the two lifting working segments (6a11).

7. The driving device for wire cutting, presser foot lifting and stitch length adjustment according to claim 6, characterized in that, the swing working surface (7a1) further includes an ineffective stitch length adjustment segment (7a12) other than the effective stitch length adjustment segment (7a11); when the most convex point of the wire cutting arc transition segment (5a12) acts on the wire cutting mechanism (1), the ineffective stitch length adjustment segment (7a12) acts on the swing ejector rod (8), and the middle area of the lifting working segment (6a11) acts on the presser foot lifting mechanism (2); when the most convex point of the lifting arc transition segment (6a12) acts on the presser foot lifting mechanism (2), the ineffective stitch length adjustment segment (7a12) acts on the swing ejector rod (8), and the middle area of the wire cutting working segment (5a11) acts on the wire cutting mechanism (1).

8. The driving device for wire cutting, presser foot lifting and stitch length adjustment according to any one of claims 1-4, characterized in that, A rotatable stitch pitch adjusting roller (8a) is provided on the swing ejector rod (8), and the stitch pitch adjusting roller (8a) abuts against the outer peripheral wall of the stitch pitch adjusting cam (7) and can roll along the outer peripheral wall of the stitch pitch adjusting cam (7); the presser foot lifting mechanism (2) includes a lifting ejector rod (2a), a mounting seat (2a1) is fixed to the lower end of the lifting ejector rod (2a), a rotatable presser foot lifting roller (2a2) is connected to the mounting seat (2a1), and the presser foot lifting roller (2a2) abuts against the outer peripheral wall of the presser foot lifting cam (6) and can roll along the outer peripheral wall of the presser foot lifting cam (6).

9. The driving device for thread trimming, presser foot lifting and stitch pitch adjustment according to any one of claims 1-4, characterized in that the stitch pitch adjusting mechanism (3) includes a rotatable swing plate seat (3a) connected to the sewing machine base (11), the swing ejector rod (8) is fixedly connected to the swing plate seat (3a), a support seat (9) is fixedly connected to the base (11) of the sewing machine, the rotating shaft (4a) of the motor (4) is supported on the support seat (9), and a holding spring (3c) for keeping the swing ejector rod (8) abutted against the stitch pitch adjusting cam (7) is fixedly connected between the swing plate seat (3a) and the support seat (9).

10. The driving device for thread trimming, presser foot lifting and stitch pitch adjustment according to claim 9, characterized in that a fixing plate (8b) is provided on the upper end of the swing ejector rod (8), and the fixing plate (8b) abuts against and is fixed to the lower surface of the swing plate seat (3a).

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