Thick and thin material detection device of sewing machine

Abstract

The utility model provides a thick and thin material detection device of a sewing machine, which comprises a machine shell, a Hall sensor fixed on the machine shell through a sensor support is arranged in the machine shell, and magnetic steel connected with a pressing rod guide frame through a magnetic steel support is arranged in the machine shell. According to the sewing machine applying the thick and thin material detection device, the pressure of the presser foot can be automatically adjusted in real time according to the thickness change of the sewing material, and the working mode of the sewing machine can be adjusted according to the thickness change of the sewing material, so that when sewing materials with different thicknesses are sewn, the problems of no ridge crossing, thin material wrinkling, thick material stitch skipping or thread breaking and the like are not prone to occurring, and the sewing efficiency is improved. The sewing machine with the thick and thin material detection device has the advantage of being good in sewing effect.

Description

Technical Field

[0001] This utility model relates to the technical field of sewing machines, and in particular to a device for detecting the thickness of materials in a sewing machine. Background Technology

[0002] A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on fabric, so that one or more layers of fabric are interwoven or sewn together. A sewing machine generally includes a machine head, a machine base, a transmission system, and a control system.

[0003] The sewing machine head is a crucial component, comprising four main mechanisms: needle insertion, thread hooking, thread take-up, and feed. It also includes auxiliary mechanisms such as thread winding, pressing, and feed dog. The pressing mechanism typically includes a presser foot mounted on the needle bar. Before sewing begins, the operator manually raises the presser foot, places the fabric directly beneath it and the needle, and then manually lowers the presser foot. Sewing can then commence, with the operator controlling the sewing speed by pressing a foot pedal. Throughout the sewing process, the presser foot keeps the fabric pressed firmly against the feed dog to facilitate fabric movement.

[0004] The existing Chinese patent with authorization announcement number CN109722798B discloses a thread-cutting and presser foot lifting mechanism for a sewing machine, including a rotary drive source, a presser foot lifting drive assembly, a presser foot lifting transmission assembly, and a presser foot lifting device. A double-headed crank including a presser foot lifting drive crank is fixed on the output shaft of the rotary drive source, and the presser foot lifting drive crank has a connecting member two.

[0005] The presser foot drive assembly includes a presser foot drive linkage, a second groove that is opened along the length of the presser foot drive linkage and slides in cooperation with the second connector, and a presser foot crank that is hinged to the end of the presser foot drive linkage away from the second groove.

[0006] The presser foot lifting transmission assembly includes a presser foot shaft connected to the presser foot crank, a push rod crank with its fixed end connected to the presser foot shaft, and a push rod with its lower end abutting against the movable end of the push rod crank.

[0007] The presser foot lifting device includes a rear presser foot lever, a front presser foot lever, a presser foot lifting plate, a presser rod guide, and a presser rod. The middle part of the rear presser foot lever is rotatably mounted on the sewing machine head. The rear end of the rear presser foot lever is hinged to the upper end of the top rod. The front end of the rear presser foot lever is connected to the front presser foot lever via a pull rod. The middle part of the front presser foot lever is rotatably mounted on the sewing machine head. The lower end of the front presser foot lever is hinged to the upper end of the presser foot lifting plate. The lower end of the presser foot lifting plate is abutted against the presser rod guide. The presser rod guide is fixed to the presser rod, and the presser foot plate is located at the lower end of the presser rod. The presser foot plate achieves its reset action through an adjusting screw assembly, an adjusting spring, and an adjusting guide rod.

[0008] When it is necessary to lift the presser foot plate, the rotary drive source drives the double-headed crank to rotate, causing the connecting part two on the double-headed crank to move closer to the right end of the slide groove two until it contacts it, which drives the presser foot lifting drive linkage to swing, thereby driving the presser foot lifting shaft to swing, causing the push rod crank to swing, lifting the push rod, and thus driving the presser foot plate to rise through the presser foot rear lever, presser foot front lever, presser foot lifting plate, and press rod guide frame.

[0009] When the presser foot needs to be lowered, the rotary drive source drives the double-headed crank to rotate and reset, and the presser foot is reset under the action of the pressure adjusting spring.

[0010] The existing technical solutions mentioned above have the following drawbacks: When a sewing machine using the thread-cutting and presser foot lifting mechanism is working, the pressure of the presser foot plate on the fabric is usually fixed. It is difficult for the presser foot plate to automatically adjust the pressure in real time according to the changes in the thickness of the fabric. Therefore, when sewing fabrics of different thicknesses, problems such as not passing the seam allowance, wrinkling of thin fabrics, skipped stitches or broken threads in thick fabrics are likely to occur, resulting in poor sewing effect and failure to achieve the expected results. Utility Model Content

[0011] The present invention aims to address the aforementioned shortcomings in the prior art by providing a sewing machine thickness detection device, which solves the problem of poor sewing effect in the prior art.

[0012] The above-mentioned utility model objective is achieved through the following technical solution: a sewing machine thickness detection device, including a machine housing, a Hall sensor fixed to the machine housing by a sensor bracket inside the machine housing, and a magnet connected to the pressure rod guide frame by a magnet bracket inside the machine housing.

[0013] The present invention is further configured such that: an upper mounting hole is provided at the upper end of the sensor bracket, and an upper bracket fastener for fixing the upper end of the sensor bracket to the upper part of the housing is inserted through the upper mounting hole.

[0014] The present invention is further configured such that: a connecting post with a connecting hole in the middle is provided on the sensor bracket, a connecting plate is provided on the side wall of the Hall sensor corresponding to the connecting post, a plate opening aligned with the connecting hole is provided on the connecting plate, and a sensor fastener connected to the connecting post through the connecting hole is passed through the plate opening.

[0015] The present invention is further configured such that: the upper end of the magnet bracket, which is equipped with a magnet, extends between the sensor bracket and the Hall sensor; the lower end of the magnet bracket is provided with a lower mounting hole; and a lower bracket fixing member is inserted through the lower mounting hole to fix the lower end of the magnet bracket to the pressure rod guide.

[0016] The present invention is further configured such that: an installation groove is provided on the outer side wall of the upper end of the magnet bracket, and the magnet is embedded in the installation groove by means of interference fit.

[0017] The present invention is further configured such that the magnet is fixed to the upper end of the magnet bracket by sealant.

[0018] The present invention is further configured such that: a through hole is provided on the side wall of the housing, a plug with a wire outlet hole in the middle is inserted into the through hole, a wire hole is provided on the sensor bracket, and the Hall sensor is electrically connected to a connecting wire whose other end passes through the wire hole and the wire outlet hole in sequence and is connected to the control system.

[0019] The present invention is further configured such that: the lower bracket fixing component is a quick release device, the quick release device includes a quick release plug that passes through the lower mounting hole and is inserted into the quick release socket and has an internal cavity, a positioning plate disposed on the outer wall of the quick release plug and abutting against the end face of the magnet bracket away from the pressure rod guide, a guide head sliding hole disposed on the outer wall of the quick release plug and communicating with the internal cavity, an extended locking head slidably disposed in the guide head sliding hole, and a control mechanism for controlling the extended locking head to reciprocate linearly along the guide head sliding hole.

[0020] The present invention is further configured such that: the control mechanism includes a quick-release central shaft rotatably disposed in the inner cavity, and a connecting rod having one end hinged to the quick-release central shaft via a hinge seat and the other end hinged to an external locking head.

[0021] The present invention is further configured such that: the quick-release plug has an outlet hole communicating with the inner cavity; the quick-release central shaft extends out of the inner cavity and is connected to a quick-release shaft head; the end of the quick-release shaft head away from the quick-release central shaft is hinged with a limit buckle; and the outer wall of the quick-release plug has a limit groove that engages with the limit buckle.

[0022] In summary, the beneficial technical effects of this utility model are as follows:

[0023] (1) A sewing machine using this material thickness detection device can automatically adjust the presser foot pressure in real time according to the change in the thickness of the material, and can also adjust the working mode of the sewing machine according to the change in the thickness of the material. Therefore, when sewing materials of different thicknesses, it is not easy to encounter problems such as not passing the seam, wrinkling of thin materials, skipping stitches or breaking threads of thick materials. A sewing machine using this material thickness detection device has the advantage of good sewing effect.

[0024] (2) The thickness detection device of this sewing machine fixes the Hall sensor to the upper part of the machine housing through the sensor bracket. On the one hand, the upper part of the machine housing has a thicker wall and more space, so the sensor bracket can be installed by drilling holes in the machine housing without redesigning the machine housing and the machine housing mold. On the other hand, the risk of the Hall sensor being splashed or accumulated by oil is reduced.

[0025] (3) The thickness detection device of this sewing machine uses a positioning installation method to make the connecting line difficult to separate from the Hall sensor, and also prevents the connecting line from interfering with various existing moving parts inside the machine housing. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the sewing machine and the thickness detection device in Embodiment 1;

[0027] Figure 2 This is a schematic diagram of the sensor bracket, Hall sensor, and magnet bracket in Embodiment 1;

[0028] Figure 3 This is a schematic diagram of the sensor bracket structure in Embodiment 1;

[0029] Figure 4 This is a schematic diagram of the Hall sensor structure in Embodiment 1;

[0030] Figure 5 This is a schematic diagram of the magnet and magnet support in Embodiment 1;

[0031] Figure 6 This is a schematic diagram of the casing, plug, and cable outlet in Embodiment 1;

[0032] Figure 7 This is a schematic diagram of the plug structure in Example 1;

[0033] Figure 8 This is a cross-sectional view of the pressure rod guide, magnet bracket, and quick release device in Embodiment 2;

[0034] Figure 9 This is a cross-sectional structural diagram of the quick-release device in Embodiment 2.

[0035] In the above attached diagrams: 1. Housing; 2. Pressure rod; 3. Pressure rod guide; 31. Quick-release socket; 32. Locking hole; 4. Pressure foot; 5. Needle plate; 6. Sensor bracket; 7. Upper mounting hole; 8. Connecting post; 9. Connecting hole; 10. Hall sensor; 101. Connecting plate; 102. Plate opening; 11. Magnet bracket; 111. Mounting slot; 112. Lower mounting hole; 12. Magnet; 13. 14. Hole plug; 141. Cable outlet hole; 15. Cable threading hole; 16. Connecting wire; 17. Quick release device; 18. Quick release plug; 19. Inner cavity; 20. Shaft outlet hole; 21. Positioning plate; 22. Guide head sliding hole; 23. Outward locking head; 24. Quick release central shaft; 25. Connecting rod; 26. Hinge seat; 27. Quick release shaft head; 28. Limiting buckle; 29. ​​Limiting slot; 30. Guide plate. Detailed Implementation

[0036] To make the technical means, creative features, objectives and effects of this utility model clearer and easier to understand, the present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, the existing sewing machine includes a housing 1, a presser bar 2 that is movably mounted on the housing 1, a presser bar guide 3 that is fixedly mounted on the upper part of the presser bar 2, a presser foot 4 that is fixedly mounted on the bottom of the presser bar 2, and a needle plate 5 that is located below the presser foot 4.

[0038] Example 1:

[0039] like Figure 1 and 2 As shown, this utility model proposes a device for detecting the thickness of materials in a sewing machine, including a machine housing 1, a sensor bracket 6, a Hall sensor 10, a magnet bracket 11, and a magnet 12.

[0040] like Figure 1 and 3 As shown in this embodiment, the upper end of the sensor bracket 6 has two upper mounting holes 7. Upper bracket fasteners for fixing the upper end of the sensor bracket 6 to the upper part of the housing 1 are inserted through the upper mounting holes 7. The upper bracket fasteners are screws or pins. The housing 1 is connected to the upper bracket fasteners by opening screw holes for threaded connection with screws or pin holes for insertion with pins.

[0041] The thickness detection device of this sewing machine fixes the Hall sensor 10 to the upper part of the machine housing 1 through the sensor bracket 6. On the one hand, the upper part of the machine housing 1 has a thick wall and sufficient space, so the sensor bracket 6 can be installed by drilling holes in the machine housing 1 without redesigning the machine housing 1 and the machine housing mold. On the other hand, the risk of the Hall sensor 10 being affected by oil splashes or oil accumulation is reduced.

[0042] like Figure 1 and 3 As shown, in this embodiment, three cylindrical connecting posts 8 are fixedly connected to the end face of the sensor bracket 6 away from the housing 1. The three connecting posts 8 are arranged in a triangle. A connecting hole 9 is opened in the middle of the connecting post 8. The connecting hole 9 is a screw hole or a pin hole.

[0043] The Hall sensor 10 is an electronic component based on the Hall effect, mainly used to detect changes in magnetic field and convert them into electrical signals. The seams of the Hall sensor 10's housing are filled with sealant, which is selected as an acrylate sealant, silicone sealant, or other sealant with good oil resistance. This helps to prevent oil penetration and, to some extent, avoids reducing the sensing intensity or damaging the parts.

[0044] like Figure 1 and 4As shown, three connecting plates 101 are fixedly connected to the side wall of the Hall sensor 10, each corresponding to one of the three connecting posts 8. The connecting plates 101 abut against the end faces of the connecting posts 8 that are away from the sensor bracket 6. The connecting plates 101 have openings 102 aligned with the connecting holes 9. Sensor fasteners are inserted through the openings 102. The sensor fasteners are screws that are threaded into screw holes or pins that are inserted into pin holes.

[0045] like Figure 2 and 5 As shown, the magnet 12 is fixed to the upper end of the magnet bracket 11 with a highly oil-resistant sealant. The sealant is selected from oil-resistant materials such as acrylic sealant and silicone sealant. The upper end of the magnet bracket 11, where the magnet 12 is mounted, extends between the sensor bracket 6 and the Hall sensor 10. A mounting groove 111 is formed on the outer side wall of the upper end of the magnet bracket 11. In this embodiment, the mounting groove 111 is a rectangular groove. The magnet 12 is embedded in the mounting groove 111 by an interference fit; the magnet 12 is a rectangular block.

[0046] like Figure 2 As shown, in this embodiment, the distance between the magnet 12 and the outer wall of the Hall sensor 10 is m, where m is typically 0.5 mm.

[0047] like Figure 1 and 5 As shown, in this embodiment, the lower end of the magnet bracket 11 has two elliptical cross-section lower mounting holes 112. The lower mounting holes 112 are provided with lower bracket fixing members to fix the lower end of the magnet bracket 11 to the side wall of the pressure rod guide 3. The lower bracket fixing members are screws or pins. The pressure rod guide 3 is connected to the lower bracket fixing members by opening screw holes for threaded connection with screws or pin holes for insertion with pins.

[0048] like Figure 2 As shown, in this embodiment, when the presser foot 4 moves to the highest point, the height n between the presser foot 4 and the needle plate 5 is the maximum height of the presser foot 4. n is usually 13mm. When the presser foot 4 moves within the range of 0 to n, the magnet 12 and the magnet bracket 11 do not interfere with the Hall sensor 10 and the sensor bracket 6.

[0049] like Figure 6 and 7 As shown, a through hole 13 is provided on the side wall of the housing 1, and a plug 14 with a wire outlet hole 141 in the middle is inserted into the through hole 13. The plug 14 is an "I"-shaped plug. A wire hole 15 is provided on the sensor bracket 6. The wire hole 15 is a circular hole. The Hall sensor 10 is electrically connected to a connecting wire 16. The end of the connecting wire 16 away from the Hall sensor 10 passes through the wire hole 15 and the wire outlet hole 141 in sequence and is connected to the control system. The connecting wire 16 is tied to the wire hole 15 with a cable tie.

[0050] The thickness detection device of this sewing machine uses a positioning installation method for the connecting line 16, which makes it difficult for the connecting line 16 to separate from the Hall sensor 10, and also prevents the connecting line 16 from interfering with various existing moving parts inside the machine housing 1.

[0051] In this embodiment, the detailed working process of the Hall sensor 10 is as follows: Since the magnet 12 is fixed on the pressure rod guide 3 through the magnet bracket 11, the relative position of the magnet 12 and the pressure foot 4 is fixed. When the magnet 12 moves up and down with the pressure rod 2, the Hall sensor 10 can determine the real-time position of the pressure foot 4 by detecting the change in the magnetic field of the magnet 12.

[0052] In this embodiment, the installation process of the magnet bracket 11 is as follows: When the worker manually lifts the presser foot 4, a height block (height X) will be placed under the presser foot 4. After determining the relative position of the pressure rod guide 3 and the presser foot 4, the position of the magnet 12 and the magnet bracket 11 will be finely adjusted according to the signal strength displayed by the control system, so that the magnet 12 is at or near the point of strongest signal. In this way, the height difference X can be regarded as the point of strongest signal, which is convenient for the control system to perform data processing.

[0053] The detailed working process of the thickness detection device in this embodiment is as follows:

[0054] S1: When the presser foot 4 and the needle plate 5 are in contact, the height difference between them is 0;

[0055] S2: During sewing, when the height difference between presser foot 4 and needle plate 5 is greater than 0 and less than X due to pressing down on the sewing material, the control system determines it to be a thin material sewing mode and does not take any action.

[0056] S3: During sewing, when the height difference between the presser foot 4 and the needle plate 5 is greater than or equal to X due to pressing down on the fabric or going over a curb, the control system judges it as a thick material sewing mode. The control system changes the working parameters of each working mechanism (such as the pressing pressure of the presser foot 4, the motor speed, etc.) so that the sewing machine can adapt to the sewing of thick materials.

[0057] Since the feeding relies on the interaction between the feed dog and presser foot 4, and the feed dog's movement trajectory is elliptical and partially lies on the needle plate 5, a compensation height 'a' is introduced. When the feed dog's teeth are at their highest point, the height difference between presser foot 4 and needle plate 5 is greater than or equal to X, at which point it is determined to be a thick material sewing mode. Then the feed dog falls, causing the height difference between presser foot 4 and needle plate 5 to be greater than or equal to Xa and less than X. If it is determined to be a thin material sewing mode at this time, it will cause the control system to switch frequently, affecting the overall stability and the actual sewing effect. Therefore, it is still determined to be a thick material sewing mode at this time until the height difference is less than Xa, and then it is determined to be a thin material sewing mode.

[0058] One sewing motion is considered as one cycle. The maximum height difference within a cycle is used as the criterion. If the maximum height difference within a cycle is less than X, the cycle is determined to be a thin material sewing mode. If the maximum height difference within a cycle is greater than or equal to X, the cycle is determined to be a thick material sewing mode. This solution requires a strong control system and is a secondary option.

[0059] Sewing machines using this material thickness detection device can automatically adjust the pressure of presser foot 4 in real time according to changes in material thickness. They can also adjust the working mode of the sewing machine according to changes in material thickness. Therefore, when sewing materials of different thicknesses, problems such as not going over the seam, wrinkling of thin materials, skipped stitches or broken threads of thick materials are less likely to occur. Sewing machines using this material thickness detection device have the advantage of good sewing effect.

[0060] Example 2:

[0061] This utility model proposes a device for detecting the thickness of materials in a sewing machine. The difference between Embodiment 2 and Embodiment 1 is that the lower support fixing component is a quick release device 17.

[0062] like Figure 8 As shown, the pressure rod guide 3 in the prior art has a quick-release insertion hole 31 with a circular cross-section on its side wall. The quick-release insertion hole 31 has a locking hole 32 circumferentially opened on its wall. The locking hole 32 has an annular cross-section.

[0063] like Figure 8 and 9 As shown, the quick-release device 17 includes a cylindrical quick-release plug 18. The quick-release plug 18 passes through the lower mounting hole 112 of the magnet bracket 11 and is inserted into the quick-release insertion hole 31 of the pressure rod guide 3. The quick-release plug 18 has an inner cavity 19 with a circular cross-section. The end face of the quick-release plug 18 away from the pressure rod guide 3 has a shaft outlet hole 20 with a circular cross-section, which communicates with the inner cavity 19.

[0064] like Figure 8 and 9 As shown, a positioning plate 21 is fixedly connected to the outer wall of the quick-release plug 18. The cross-section of the positioning plate 21 is circular. When the quick-release device 17 is installed on the magnetic steel bracket 11, the positioning plate 21 abuts against the end face of the magnetic steel bracket 11 away from the pressure rod guide 3.

[0065] like Figure 8 and 9 As shown, two guide slide holes 22 are symmetrically formed on the outer side wall of the quick-release plug 18, and the cross-section of the guide slide holes 22 is rectangular. An extended locking head 23 is slidably disposed in each guide slide hole 22. In this embodiment, the extended locking head 23 is a rectangular plate. After the extended locking head 23 slides out of the guide slide hole 22, it can be inserted into the locking hole 32.

[0066] like Figure 8 and 9 As shown, a control mechanism is provided in the inner cavity 19 of the quick-release lock head. The control mechanism can control the extended lock head 23 to reciprocate linearly along the guide slide hole 22, thereby causing the extended lock head 23 to slide out of the guide slide hole 22 and insert into the locking hole 32, or the extended lock head 23 to be pulled out of the locking hole 32 and retracted into the guide slide hole 22 and the inner cavity 19.

[0067] like Figure 8 and 9 As shown, the control mechanism includes a quick-release central shaft 24 and a connecting rod 25. The quick-release central shaft 24 is rotatably mounted at the center of the inner cavity 19. One end of the connecting rod 25 is hinged to the quick-release central shaft 24 via a hinge seat 26, and the other end is hinged to the outward locking head 23.

[0068] like Figure 8 and 9 As shown, the quick-release central shaft 24 extends out of the inner cavity 19 of the quick-release plug 18 through the shaft outlet hole 20 that rotatably engages with it. After extending out of the inner cavity 19, the quick-release central shaft 24 is fixedly connected to a quick-release shaft head 27, which provides a force point for the worker to rotate the quick-release central shaft 24. A limit buckle 28 is hinged to the end of the quick-release shaft head 27 away from the quick-release central shaft 24. A limit groove 29 is provided on the outer wall of the quick-release plug 18 to engage with the limit buckle 28. The limit groove 29 is a rectangular groove.

[0069] like Figure 8 and 9 As shown, a disc-shaped guide plate 30 is coaxially arranged on the quick-release central shaft 24. The guide plate 30 rotates with the inner cavity 19 of the quick-release plug 18, which helps to improve the rotational stability of the quick-release central shaft 24.

[0070] In this embodiment, the detailed installation process of the quick-release device 17 is as follows: the quick-release plug 18 passes through the lower mounting hole 112 of the magnet bracket 11 and is inserted into the quick-release insertion hole 31 of the pressure rod guide 3. At this time, the positioning plate 21 abuts against the end face of the magnet bracket 11 away from the pressure rod guide 3. Then, the worker rotates the quick-release central shaft 24 through the quick-release shaft head 27. The rotation of the quick-release central shaft 24 will push the extended locking head 23 out of the guide head sliding hole 22 and into the locking hole 32 through the connecting rod 25. Then, the worker rotates the limiting buckle 28 so that the limiting buckle 28 is embedded in the limiting slot 29. At this time, the quick-release shaft head 27 and the quick-release central shaft 24 are restricted from rotation, and the extended locking head 23 remains inserted into the locking hole 32.

[0071] The thickness detection device of this sewing machine uses a quick release device 17 to fix the lower end of the magnetic steel bracket 11 to the pressure rod guide frame 3. The quick release device 17 can be removed or installed without the need for tools such as screwdrivers, making it convenient to disassemble and assemble.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A device for detecting the thickness of materials in a sewing machine, comprising a machine housing (1), characterized in that: A Hall sensor (10) is fixed to the housing (1) by a sensor bracket (6) inside the housing (1), and a magnet (12) is connected to the pressure rod guide (3) by a magnet bracket (11) inside the housing (1).

2. The material thickness detection device for a sewing machine according to claim 1, characterized in that: The upper end of the sensor bracket (6) is provided with an upper mounting hole (7), and an upper bracket fastener for fixing the upper end of the sensor bracket (6) to the upper part of the housing (1) is inserted through the upper mounting hole (7).

3. The material thickness detection device for a sewing machine according to claim 1, characterized in that: The sensor bracket (6) is provided with a connecting post (8) with a connecting hole (9) in the middle. The Hall sensor (10) is provided with a connecting plate (101) on its side wall corresponding to the connecting post (8). The connecting plate (101) is provided with a plate opening (102) aligned with the connecting hole (9). A sensor fastener that is connected to the connecting post (8) through the connecting hole (9) is inserted into the plate opening (102).

4. The material thickness detection device for a sewing machine according to claim 1, characterized in that: The upper end of the magnet (12) mounted on the magnet bracket (11) extends between the sensor bracket (6) and the Hall sensor (10). The lower end of the magnet bracket (11) is provided with a lower mounting hole (112). A lower bracket fixing member is inserted through the lower mounting hole (112) to fix the lower end of the magnet bracket (11) to the pressure rod guide (3).

5. The material thickness detection device for a sewing machine according to claim 4, characterized in that: An installation groove (111) is provided on the outer side wall of the upper end of the magnet bracket (11), and the magnet (12) is embedded in the installation groove (111) by interference fit.

6. A sewing machine thickness detection device according to claim 4 or 5, characterized in that: The magnet (12) is fixed to the upper end of the magnet bracket (11) with sealant.

7. The material thickness detection device for a sewing machine according to claim 1, characterized in that: The housing (1) has a through hole (13) on its side wall. A plug (14) with a wire outlet hole (141) in the middle is inserted into the through hole (13). The sensor bracket (6) has a through hole (15). The Hall sensor (10) is electrically connected to a connecting line (16) whose other end passes through the through hole (15) and the wire outlet hole (141) in sequence and is connected to the control system.

8. The material thickness detection device for a sewing machine according to claim 4, characterized in that: The lower bracket fixing component is a quick release device (17). The quick release device (17) includes a quick release plug (18) that passes through the lower mounting hole (112) and is inserted into the quick release socket (31) and has an inner cavity (19); a positioning plate (21) that is set on the outer wall of the quick release plug (18) and abuts against the end face of the magnet bracket (11) away from the pressure rod guide frame (3); a guide head sliding hole (22) that is opened on the outer wall of the quick release plug (18) and communicates with the inner cavity (19); an extension lock head (23) that is slidably set in the guide head sliding hole (22); and a control mechanism that controls the extension lock head (23) to reciprocate linearly along the guide head sliding hole (22).

9. The material thickness detection device for a sewing machine according to claim 8, characterized in that: The control mechanism includes a quick-release central shaft (24) rotatably disposed in the inner cavity (19), a connecting rod (25) with one end hinged to the quick-release central shaft (24) via a hinge seat (26) and the other end hinged to the outward lock head (23).

10. A sewing machine thickness detection device according to claim 9, characterized in that: The quick-release plug (18) has an outlet hole (20) communicating with the inner cavity (19). The quick-release central shaft (24) extends out of the inner cavity (19) and is connected to a quick-release shaft head (27). The end of the quick-release shaft head (27) away from the quick-release central shaft (24) is hinged to a limit buckle (28). The outer side wall of the quick-release plug (18) has a limit groove (29) that engages with the limit buckle (28).

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