Sewing machine with needle distance adjustment mechanism

Abstract

The present invention provides a sewing machine with a needle distance adjustment mechanism, belonging to the technical field of sewing equipment. It solves the technical problem that the existing sewing machine with a needle distance adjustment mechanism has an untidy appearance. The present invention comprises a machine body and a shell connected to the head of the machine body, wherein a chamber 1 is provided in the shell, wherein a spindle motor for controlling the operation of the sewing machine is provided in the chamber 1, and an air inlet connected to the chamber 1 is provided on the shell, and a heat sink is provided at the air inlet, and the output shaft of the spindle motor can drive the heat sink to rotate and dissipate heat for the spindle motor, and the needle distance adjustment mechanism comprises a stepper motor, wherein a chamber 2 is provided in the shell, and the stepper motor is fixed to the head of the machine body and located in the chamber 2, and an air outlet connected to the chamber 2 is provided on the shell, and an air duct connecting the chamber 1 with the chamber 2 is provided in the shell. The sewing machine with a needle distance adjustment mechanism has the advantages of a neat appearance and the like.

Description

Technical Field

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

[0002] A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on the sewing material, so that one or more layers of sewing material are interwoven or sewn together. Traditional sewing machines cannot adjust the stitch length. When sewing is finished, the bottom thread and the surface thread cannot form an effective self-locking, resulting in unsightly stitches and affecting the quality of clothing. For this reason, sewing machines with stitch length adjustment structures have appeared on the market, such as the stitch length control device of the sewing machine disclosed in the application number 201320234080.8. The reverse stitch electromagnet installed on the lower side of the table of the sewing machine drives the feed regulator to adjust the stitch length through a transmission device. A stitch length return to zero electromagnet is provided on one side of the reverse stitch electromagnet. The stitch length return to zero electromagnet drives the feed regulator through a transmission device to adjust the stitch length to near zero. The specific structure of the stitch length return to zero electromagnet to adjust the stitch length to near zero is: the middle part of the lever is hinged on the support shaft, and the outer end of the power arm of the lever is connected to the iron of the reverse stitch electromagnet. The core is connected, the outer end of the resistance arm is connected to one end of the transmission device, a pin shaft parallel to the support shaft is arranged on the power arm or the resistance arm of the lever, a rocker arm is coaxially hinged on the support shaft of the lever, a needle distance zeroing electromagnet is arranged on one side of the reverse stitch electromagnet, the iron core of the needle distance zeroing electromagnet is hinged to the outer side of the rocker arm, and the pin shaft extends into the arc groove arranged on the rocker arm. When the needle distance zeroing electromagnet is powered off, the arc groove does not limit the rotation of the pin shaft driven by the reverse stitch electromagnet. After the needle distance zeroing electromagnet is powered on, the iron core of the needle distance zeroing electromagnet drives the pin shaft to rotate and then drives the feeding regulator through the transmission device to control the needle distance close to zero. However, the needle distance adjustment structure using electromagnets generally has the problems of high noise and inaccurate and unreliable action.

[0003] In order to solve the above problems, people have improved the traditional mechanism and adopted a stepper motor to replace the electromagnet to drive the feed shaft to rotate. Since the rotation angle of the stepper motor output shaft is controllable, the rotation angle of the feed shaft is also controllable, thereby realizing the pattern sewing method of the sewing machine. However, since this method adds a motor compared to the traditional sewing machine, in order to consider the problem of heat dissipation, the conventional practice is to install the motor in an external structure to dissipate heat by directly exchanging heat with the external air, such as a sewing machine needle distance adjustment mechanism disclosed in application number 201910262278.9 (the stepper motor adopts a back-hanging structure), a sewing machine needle distance adjustment mechanism disclosed in application number 201621095675.X (the stepper motor is fixed to the front end of the sewing machine bottom plate), and an automatic needle distance adjustment mechanism disclosed in application number 201520317133.1 (the stepper motor adopts a back-hanging structure). Summary of the invention

[0004] The purpose of the present invention is to solve the above problems existing in the prior art and to propose a sewing machine with a needle distance adjustment mechanism, thereby solving the technical problem that the existing sewing machines with needle distance adjustment mechanisms have an untidy appearance.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A sewing machine with a needle distance adjustment mechanism comprises a machine body and a shell connected to the head of the machine body, wherein a chamber 1 is arranged in the shell, a spindle motor for controlling the operation of the sewing machine is arranged in the chamber 1, an air inlet connected to the chamber 1 is arranged on the shell, a heat sink is arranged at the air inlet, an output shaft of the spindle motor can drive the heat sink to rotate and dissipate heat for the spindle motor, the needle distance adjustment mechanism comprises a stepper motor, and is characterized in that a chamber 2 is arranged in the shell, the stepper motor is fixed to the head of the machine body and is located in the chamber 2, an air outlet connected to the chamber 2 is arranged on the shell, and an air duct connecting the chamber 1 with the chamber 2 is arranged in the shell.

[0007] When the sewing machine is working, the spindle motor is in operation and drives the heat sink to rotate. The rotation of the heat sink accelerates the flow of air to form external wind and is introduced into chamber one from the air inlet, then enters chamber two from the air duct and finally flows out from the air outlet, realizing internal and external circulation. During the flow of external wind, the external wind will exchange heat with the spindle motor and stepper motor in turn to achieve heat dissipation, thereby ensuring the service life of the spindle motor and stepper motor.

[0008] The sewing machine with a needle distance adjustment mechanism is provided with an air duct and an air outlet so that the wind entering the first chamber can flow through the second chamber for heat dissipation, thereby solving the heat dissipation problem that the stepper motor cannot be directly arranged in the shell, so that the stepper motor can be integrated in the shell and no longer exposed. At the same time, the shell is connected to the head of the machine body to form an integrated structure with the machine body, so that the sewing machine can realize the needle distance adjustment function by using the stepper motor and its appearance can also be more neat and beautiful.

[0009] In the above-mentioned sewing machine with a needle distance adjustment mechanism, the stepper motor and the main shaft motor are arranged in the same direction, and the stepper motor is located below the main shaft motor.

[0010] The stepper motor and the spindle motor are arranged in the same direction, and the stepper motor is located below the spindle motor. This eliminates the need to increase the volume of the housing accordingly, retains the integrity of the housing after being connected to the body, and makes the appearance neater.

[0011] In the above-mentioned sewing machine with a needle length adjustment mechanism, the side of the shell opposite to the head of the body is open, and partition plate 1 and partition plate 2 are fixedly connected to the shell. Chamber 1 is surrounded by partition plate 1 and the inner wall of the shell, and chamber 2 is surrounded by partition plate 2 and the inner wall of the shell. The edge of the shell opening protrudes from partition plate 1 and partition plate 2, and the air duct is the part of the shell protruding from partition plate 1 and partition plate 2.

[0012] The open edge of the shell protrudes from the partition one used to enclose chamber one and the partition two used to enclose chamber two, which is equivalent to that chamber one and chamber two are connected at the part of the shell protruding from the partition one and the partition two. In this way, this part can be directly used as an air duct, so that the external air entering chamber one can flow smoothly into chamber two to dissipate the heat of the stepper motor, thereby ensuring that the stepper motor can be installed in chamber two to make the appearance of the sewing machine more tidy.

[0013] In the above-mentioned sewing machine with a needle distance adjustment mechanism, the shell includes a top plate, a bottom plate, two side plates connected between the top plate and the bottom plate, and an outer plate fixedly connected between the top plate, the bottom plate and the two side plates. Partition 1 is L-shaped and fixedly connected between the top plate, the outer plate and the one side plate. Partition 2 is in an inverted L-shape and fixedly connected between the bottom plate, the outer plate and the one side plate. Partition 1 and partition 2 are fixedly connected to the same side plate. The top plate, the bottom plate and the two side plates all extend beyond the edges of partition 1 and partition 2. The air inlet is arranged on the outer plate.

[0014] The top plate, the bottom plate, the two side plates and the outer plate form a structure with one side of the housing open. The top plate, the bottom plate and the two side plates extend beyond the edges of the partition plate 1 and the partition plate 2, so that the chamber 1 and the chamber 2 can be connected by using the part of the housing protruding outside the partition plate 1 and the partition plate 2 as an air duct, thereby ensuring that the stepper motor disposed in the chamber 2 can also effectively dissipate heat.

[0015] In the above-mentioned sewing machine with a needle distance adjustment mechanism, as another technical solution, the shell includes a top plate, a bottom plate, two side plates connected between the top plate and the bottom plate, and an outer plate fixedly connected between the top plate, the bottom plate and the two side plates. An L-shaped partition plate 1 and an inverted L-shaped partition plate 2 are provided in the shell. Chamber 1 is composed of partition plate 1, the top plate, the outer plate and a side plate. Chamber 2 is composed of partition plate 2, the bottom plate, the outer plate and a side plate. A partition plate 3 is fixedly connected between the end of the horizontal part of partition plate 1 and the end of the horizontal part of partition plate 2. The side plate used to form chamber 1 is the same side plate as the side plate used to form chamber 2, and an air duct is formed between partition plate 3 and the side plate.

[0016] The partition board 1 can be set so that the vertical part is fixedly connected to the top plate and the end of the horizontal part is suspended, and the partition board 2 is set so that the vertical part is fixedly connected to the bottom plate and the end of the horizontal part is suspended, and then the partition board 3 is fixedly connected between the end of the horizontal part of the partition board 1 and the end of the horizontal part of the partition board 2, and the partition board 3 is parallel to the side plate used to form the chamber 1 and the chamber 2 so that an air duct is formed between the partition board 3 and the side plate. In this way, when the heat sink rotates to accelerate the flow of air into the chamber 1, it can flow along the air duct into the chamber 2 to dissipate the heat of the stepper motor, thereby ensuring that the stepper motor can be installed in the chamber 2 to make the appearance of the sewing machine more neat.

[0017] In the above-mentioned sewing machine with a needle distance adjustment mechanism, the air outlet is arranged on the bottom plate.

[0018] The air outlet is set on the bottom plate, which is difficult to observe directly from the outside, making the appearance neater without affecting the heat dissipation and air output.

[0019] In the above-mentioned sewing machine with a needle distance adjustment mechanism, the partition one, partition two, outer plate, top plate, bottom plate and two side plates form chamber three, a heat dissipation bracket is fixed at the mouth of chamber three, a main electric control board and a stepper electric control board for driving a stepper motor are arranged in parallel in chamber three, and a wire outlet groove is provided on partition two.

[0020] By arranging a wire outlet groove on the second partition, the stepper electric control board can be arranged in the third chamber and can be directly electrically connected to the stepper motor in the shell, so that the internal space of the shell is reasonably utilized, and the wires connecting the stepper electric control board and the stepper motor are avoided from being exposed, thereby ensuring the neat appearance of the sewing machine with a needle distance adjustment mechanism.

[0021] In the above-mentioned sewing machine with a needle length adjustment mechanism, the main electric control board is located between the stepper electric control board and the heat dissipation bracket, and a plurality of electronic components are fixed on the side of the main control board facing the heat dissipation bracket, each electronic component is abutted against the heat dissipation bracket and the two are fixed to each other, and the stepper electric control board is fixed to the inner side of the heat dissipation bracket by a plurality of heat dissipation pillars, and each heat dissipation pillar passes through the main electric control board.

[0022] The main control board dissipates heat by placing electronic components against the heat dissipation bracket, while the stepper electric control board transfers heat to the heat dissipation bracket through the heat dissipation pillars. The heat dissipation of the main control board and the stepper electric control board does not interfere with each other, which provides a guarantee for the stepper electric control board to be integrated into the shell to further make the appearance more neat.

[0023] In the above-mentioned sewing machine with needle length adjustment mechanism, the stepper electric control board is located on one side of the second vertical part of the partition, and a wire plug interface is provided on the stepper electric control board near the second vertical part of the partition, and a wire outlet groove is provided on the second vertical part of the partition.

[0024] A wire plug interface is arranged near the second vertical part of the partition board on the stepper electric control board, and a wire outlet groove is arranged on the second vertical part of the partition board, which can further facilitate the electrical connection between the stepper electric control board and the stepper motor.

[0025] In the above-mentioned sewing machine with stitch length adjustment mechanism, a feed shaft is provided at the bottom of the machine body, a swing seat is fixed on the feed shaft, the stitch length adjustment mechanism also includes a reverse stitch crank and a connecting rod, the stepper motor is fixed at the head of the machine body, the output shaft of the stepper motor extends into the machine body and is fixed to one end of the reverse stitch crank, the reverse stitch crank is located above the swing seat, and the upper and lower ends of the connecting rod are respectively hinged to the other end of the reverse stitch crank and the swing seat.

[0026] During operation, the stepper motor drives the reverse stitch crank to rotate, and the reverse stitch crank rotates to pull up or push down the connecting rod, so that the swing seat hinged to the lower end of the connecting rod swings up or down, thereby driving the feed shaft to swing at the same angle to achieve stitch adjustment.

[0027] Compared with the prior art, the sewing machine with a needle distance adjustment mechanism has an air duct and an air outlet so that the wind entering chamber one can flow through chamber two to dissipate the heat of the stepper motor, so that the stepper motor can be integrated into the shell and no longer exposed. At the same time, the shell is connected to the head of the machine body to form an integrated structure with the machine body, so that the sewing machine can realize the needle distance adjustment function by using the stepper motor and its appearance can also be neater and more beautiful.

[0028] In addition, the stepper electric control board is arranged in chamber three and can be directly electrically connected to the stepper motor in the shell, which reasonably utilizes the internal space of the shell and avoids the exposure of the wires connecting the stepper electric control board and the stepper motor, further ensuring the neat appearance of the sewing machine with a needle distance adjustment mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the sewing machine with a needle length adjustment mechanism.

[0030] Figure 2 This is a schematic diagram of the sewing machine with a needle length adjustment mechanism when it is not connected to the housing.

[0031] Figure 3 It is a schematic diagram of the shell in the first embodiment.

[0032] Figure 4 It is an exploded schematic diagram of the shell in the first embodiment.

[0033] Figure 5 The invention is a schematic diagram of the connection between the main electric control board, the stepping electric control board and the heat dissipation bracket in the sewing machine with a needle distance adjustment mechanism.

[0034] Figure 6It is a schematic diagram of the position between the stepper electric control board and the stepper motor in the first embodiment.

[0035] Figure 7 It is a structural schematic diagram of the shell in the first embodiment.

[0036] Figure 8 It is a schematic diagram of the needle distance adjustment mechanism.

[0037] Fig. 9 It is a structural schematic diagram of the shell in the second embodiment.

[0038] In the figure, 1, machine body; 2, shell; 2a, chamber one; 2b, chamber two; 2c, air duct; 2d, top plate, 2e, bottom plate; 2e1, air outlet; 2f, side plate; 2g, outer plate; 2g1, air inlet; 2h, chamber three; 3, spindle motor; 4, heat sink; 5, stepper motor; 6, partition one; 7, partition two; 7a, wire outlet slot; 8, heat dissipation bracket; 8a, connecting column; 9, main electric control board; 9a, electronic components; 10, stepper electric control board; 10a, wire plug interface; 11, heat dissipation pillar; 12, spindle; 13, feed shaft; 14, swing seat; 15, reverse stitch crank; 16, connecting rod; 17, partition three. DETAILED DESCRIPTION

[0039] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0040] Embodiment 1

[0041] like Figure 1 , Figure 2 and Figure 8 As shown, a sewing machine with a stitch length adjustment mechanism comprises a machine body 1 having a head and a housing 2 connected to the head of the machine body 1. A rotatable main shaft 12 is provided in the machine body 1, and a main shaft motor 3 that can drive the main shaft 12 to rotate is fixed at the head of the machine body 1. A rotatable feed shaft 13 is provided below the machine body 1, and the feed shaft 13 is parallel to the main shaft 12, and a swing seat 14 is fixed on the feed shaft 13. The stitch length adjustment mechanism comprises a stepper motor 5, a reverse stitch crank 15 and a connecting rod 16. The stepper motor 5 is fixed on the head of the machine body 1 and arranged in the same direction as the main shaft motor 3. The stepper motor 5 is located below the main shaft motor 3. The output shaft of the stepper motor 5 extends into the machine body 1 and is fixed to one end of the reverse stitch crank 15. The reverse stitch crank 15 is located above the swing seat 14. The upper and lower ends of the connecting rod 16 are respectively hinged to the other end of the reverse stitch crank 15 and the swing seat 14.

[0042] During operation, the reverse stitch crank 15 is driven to swing by the stepping motor 5. One end of the reverse stitch crank 15 is hinged to the upper end of the connecting rod 16. Therefore, the reverse stitch crank 15 will pull the connecting rod 16 upward or push it downward when swinging, thereby causing the swing seat 14 hinged to the lower end of the connecting rod 16 to swing upward or downward, and then drive the feed shaft 13 fixed to the swing seat 14 to swing at the same angle to achieve the adjustment of the stitch length.

[0043] like Figure 3 and Figure 4 As shown, a chamber 1 2a is provided in the upper part of the housing 2, and the spindle motor 3 is located in the chamber 1 2a. An air inlet 2g1 connected to the chamber 1 2a is provided on the housing 2, and a heat sink 4 is provided at the air inlet 2g1. The output shaft of the spindle motor 3 can drive the heat sink 4 to rotate and dissipate heat for the spindle motor 3. A chamber 2b is provided in the lower part of the housing 2, and a stepper motor 5 is located in the chamber 2b. An air duct 2c connecting the chamber 1 2a with the chamber 2 2b is provided in the housing 2, and an air outlet 2e1 connected to the chamber 2 2b is provided on the housing 2. In this embodiment, the heat sink 4 is a hand wheel with a heat dissipation function. The hand wheel with a heat dissipation function is a prior art and will not be described here. Reference may be made to a hand wheel of a sewing machine disclosed in Application No. 201220351113.2, a sewing machine disclosed in Application No. 201320031817.6, etc.

[0044] The sewing machine with a needle distance adjustment mechanism is provided with an air duct 2c and an air outlet 2e1, so that the wind entering the chamber 1 2a can flow through the chamber 2 2b for heat dissipation, thereby solving the heat dissipation problem that prevents the stepper motor 5 from being directly arranged in the shell 2, so that the stepper motor 5 can be integrated in the shell 2 and no longer exposed. At the same time, the shell 2 is connected to the head of the body 1 to form an integrated structure with the body 1, so that the sewing machine can realize the needle distance adjustment function by using the stepper motor 5 while its appearance can also be more neat and beautiful.

[0045] like Figure 4 , Figure 6 and Figure 7As shown, the side of the shell 2 opposite to the head of the body 1 is open, and a partition 6 and a partition 2 7 are fixedly connected to the shell 2. The chamber 2a is surrounded by the partition 1 6 and the inner wall of the shell 2, and the chamber 2b is surrounded by the partition 2 7 and the inner wall of the shell 2, wherein the open edge of the shell 2 protrudes outside the partition 1 6 and the partition 2 7, and the air duct 2c is the part of the shell 2 protruding outside the partition 1 6 and the partition 2 7, and the partition 1 6, the partition 2 7 and the shell 2 are an integrated structure. Specifically, the housing 2 includes a top plate 2d, a bottom plate 2e, two side plates 2f connected between the top plate 2d and the bottom plate 2e, and an outer plate 2g fixedly connected between the top plate 2d, the bottom plate 2e and the two side plates 2f. The partition 1 6 is L-shaped and fixedly connected between the top plate 2d, the outer plate 2g and the one side plate 2f. The partition 2 7 is inverted L-shaped and fixedly connected between the bottom plate 2e, the outer plate 2g and the one side plate 2f. The partition 1 6 and the partition 2 7 are fixedly connected to the same side plate 2f. The top plate 2d, the bottom plate 2e and the two side plates 2f all extend outside the edges of the partition 1 6 and the partition 2 7. A convex portion is provided on the upper part of the side of the outer plate 2g facing away from the head of the machine body 1, and the air inlet 2g1 is provided on the convex portion and penetrates the outer plate 2g. The air outlet 2e1 is provided on the bottom plate 2e.

[0046] like Figure 4 , Figure 5 and Figure 6 As shown, the partition 1 6, the partition 2 7, the outer plate 2g, the top plate 2d, the bottom plate 2e and the two side plates 2f form a chamber 3 2h, and a heat dissipation bracket 8 is fixed at the mouth of the chamber 3 2h. The heat dissipation bracket 8 is provided with a connecting column 8a on the side opposite to the head of the machine body 1, and the heat dissipation bracket 8 is fixed by a number of fasteners that pass through the shell 2, the connecting column 8a and penetrate into the head of the machine body 1 in sequence. The main electric control board 9 and the stepping electric control board 10 for driving the stepping motor 5 are arranged in the chamber 3 2h. The main electric control board 9 and the stepping electric control board 10 are arranged in parallel, and the main electric control board 9 is located between the stepping electric control board 10 and the heat dissipation bracket 8. The heat dissipation bracket 8 is an aluminum bracket, and a number of electronic components 9 are fixed on the side of the main electric control board 9 facing the heat dissipation bracket 8. The electronic components 9 are attached to the heat dissipation bracket 8 and the two are fixed. The stepper electric control board 10 is fixed to the inner side of the heat dissipation bracket 8 through a plurality of heat dissipation pillars 11. Each heat dissipation pillar 11 passes through the main electric control board 9. The heat generated by the stepper electric control board 10 is directly transferred to the heat dissipation bracket 8 by each heat dissipation pillar 11 for heat dissipation, which provides a guarantee for the stepper motor 5 to be integrated into the housing 2 to make the appearance of the sewing machine more neat. The stepper electric control board 10 is located on one side of the vertical part of the partition 2 7. The stepper electric control board 10 is provided with a wire plug interface 10a near the vertical part of the partition 2 7. The vertical part of the partition 2 7 is correspondingly provided with a wire outlet groove 7a. Through the provision of the wire outlet groove 7a, the stepper electric control board 10 and the stepper motor 5 can be directly electrically connected in the housing 2.

[0047] Embodiment 2

[0048] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: Fig. 9 As shown, in this embodiment, the side of the shell 2 opposite to the head of the body 1 is open, and the shell 2 includes a top plate 2d, a bottom plate 2e, two side plates 2f connected between the top plate 2d and the bottom plate 2e, and an outer plate 2g fixedly connected between the top plate 2d, the bottom plate 2e and the two side plates 2f. The shell 2 is provided with an L-shaped partition 16 and an inverted L-shaped partition 27. The vertical portion of the partition 16 is fixedly connected to the top plate 2d and the chamber 12a is composed of the partition 16, the top plate 2d, The chamber 2b is composed of an outer plate 2g and a side plate 2f, the vertical part of the partition 2 7 is fixedly connected to the bottom plate 2e and the chamber 2b is composed of the partition 27, the bottom plate 2e, the outer plate 2g and the side plate 2f, the partition 3 17 is fixedly connected between the end of the horizontal part of the partition 1 6 and the end of the horizontal part of the partition 2 7, the side plate 2f used to form the chamber 1 2a and the side plate 2f used to form the chamber 2 2b are the same side plate 2f, and an air duct 2c is formed between the partition 3 17 and the side plate 2f.

[0049] Embodiment 3

[0050] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: in this embodiment, the heat sink is a heat dissipation fan fixed on the output shaft of the spindle motor 3 .

[0051] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A sewing machine with a needle distance adjustment mechanism, comprising a machine body (1) and a shell (2) connected to the head of the machine body (1), wherein a chamber 1 (2a) is provided in the shell (2), a spindle motor (3) for controlling the operation of the sewing machine is provided in the chamber 1 (2a), an air inlet (2g1) connected to the chamber 1 (2a) is provided on the shell (2), a heat sink (4) is provided at the air inlet (2g1), an output shaft of the spindle motor (3) can drive the heat sink (4) to rotate and dissipate heat from the spindle motor (3), the needle distance adjustment mechanism comprises a stepping motor (5), and is characterized in that: The shell (2) is provided with a second chamber (2b), the stepper motor (5) is fixed to the head of the body (1) and is located in the second chamber (2b), the shell (2) is provided with an air outlet (2e1) connected to the second chamber (2b), the shell (2) is provided with an air duct (2c) connecting the first chamber (2a) and the second chamber (2b), the shell (2) is further provided with a third chamber (2h), and a heat dissipation bracket (8) is fixed at the mouth of the third chamber (2h). ), a main electric control board (9) and a stepper electric control board (10) for driving the stepper motor (5) are arranged in parallel in chamber three (2h), the main electric control board (9) is located between the stepper electric control board (10) and the heat dissipation bracket (8), the main electric control board (9) and the heat dissipation bracket (8) are fixed to each other, and the stepper electric control board (10) is fixed to the heat dissipation bracket (8) through a plurality of heat dissipation pillars (11), and each heat dissipation pillar (11) passes through the main electric control board (9).

2. The sewing machine with a needle length adjustment mechanism according to claim 1, characterized in that: The stepper motor (5) is arranged in the same direction as the spindle motor (3), and the stepper motor (5) is located below the spindle motor (3).

3. The sewing machine with a needle length adjustment mechanism according to claim 2, characterized in that: The shell (2) is open at a side opposite to the head of the machine body (1); a partition plate 1 (6) and a partition plate 2 (7) are fixedly connected inside the shell (2); chamber 1 (2a) is surrounded by partition plate 1 (6) and an inner wall of the shell (2); chamber 2 (2b) is surrounded by partition plate 2 (7) and an inner wall of the shell (2); an edge of the shell (2) protrudes outside the partition plate 1 (6) and the partition plate 2 (7); and the air duct (2c) is a portion of the shell (2) protruding outside the partition plate 1 (6) and the partition plate 2 (7).

4. The sewing machine with a needle length adjustment mechanism according to claim 3, characterized in that: The shell (2) comprises a top plate (2d), a bottom plate (2e), two side plates (2f) connected between the top plate (2d) and the bottom plate (2e), and an outer plate (2g) fixedly connected between the top plate (2d), the bottom plate (2e) and the two side plates (2f); the partition plate 1 (6) is L-shaped and fixedly connected between the top plate (2d), the outer plate (2g) and the one side plate (2f); the partition plate 2 (7) is in an inverted L-shape and fixedly connected between the bottom plate (2e), the outer plate (2g) and the one side plate (2f); the partition plate 1 (6) and the partition plate 2 (7) are fixedly connected to the same side plate (2f); the top plate (2d), the bottom plate (2e) and the two side plates (2f) all extend beyond the edges of the partition plate 1 (6) and the partition plate 2 (7); and the air inlet (2g1) is provided on the outer plate (2g).

5. The sewing machine with a needle length adjustment mechanism according to claim 2, characterized in that: The shell (2) comprises a top plate (2d), a bottom plate (2e), two side plates (2f) connected between the top plate (2d) and the bottom plate (2e), and an outer plate (2g) fixedly connected between the top plate (2d), the bottom plate (2e) and the two side plates (2f). An L-shaped partition plate 1 (6) and an inverted L-shaped partition plate 2 (7) are provided in the shell (2). The chamber 1 (2a) is composed of the partition plate 1 (6), the top plate (2d), the outer plate (2g) and the one side plate (2f). The chamber 2 (2b) is composed of a partition 2 (7), a bottom plate (2e), an outer plate (2g) and a side plate (2f); a partition 3 (17) is fixedly connected between the end of the horizontal portion of the partition 1 (6) and the end of the horizontal portion of the partition 2 (7); the side plate (2f) used to form the chamber 1 (2a) and the side plate (2f) used to form the chamber 2 (2b) are the same side plate (2f); and an air duct (2c) is formed between the partition 3 (17) and the side plate (2f).

6. The sewing machine with a needle length adjustment mechanism according to claim 4 or 5, characterized in that: The air outlet (2e1) is arranged on the bottom plate (2e).

7. The sewing machine with a needle length adjustment mechanism according to claim 4 or 5, characterized in that: The chamber three (2h) is surrounded by a partition plate one (6), a partition plate two (7), an outer plate (2g), a top plate (2d), a bottom plate (2e) and two side plates (2f), and a wire outlet groove (7a) is provided on the partition plate two (7).

8. The sewing machine with a needle length adjustment mechanism according to claim 7, characterized in that: The stepper electric control board (10) is located on one side of the vertical portion of the second partition (7), and a wire plug interface (10a) is provided at a position of the stepper electric control board (10) close to the vertical portion of the second partition (7), and a wire outlet groove (7a) is provided on the vertical portion of the second partition (7).

9. The sewing machine with a needle length adjustment mechanism according to claim 1, characterized in that: A feed shaft (13) is provided below the machine body (1), a swing seat (14) is fixed on the feed shaft (13), the stitch length adjustment mechanism further comprises a reverse stitch crank (15) and a connecting rod (16), a stepper motor (5) is fixed at the head of the machine body (1), an output shaft of the stepper motor (5) extends into the machine body (1) and is fixed to one end of the reverse stitch crank (15), the reverse stitch crank (15) is located above the swing seat (14), and the upper and lower ends of the connecting rod (16) are respectively hinged to the other end of the reverse stitch crank (15) and the swing seat (14).

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