Rotating shuttle and lock stitch sewing machine

Abstract

The rotating shuttle comprises a shuttle shell assembly and a shuttle peg assembly, the shuttle shell assembly comprises an outer shell with an installation cavity and a hook tip fixedly connected to the outer shell, and the shuttle peg assembly is rotatably installed in the installation cavity of the outer shell. The shuttle peg assembly is provided with a first needle protection face and a second needle protection face which are arranged in the axial direction of the shuttle peg assembly in a spaced mode so that a receding notch used for receding a machine needle of the sewing machine can be formed between the first needle protection face and the second needle protection face, and the first needle protection face is arranged towards the hook tip. The shuttle peg assembly is further provided with a groove which is sunken in the direction away from the hook tip from the first needle protection face and used for containing a thread ring which is located at a needle hole of the machine needle and faces one side of the first needle protection face. In this way, when the machine needle drives the upper thread to descend to the lowest point, the upper thread is just clamped in the groove, and in the process that the machine needle ascends to the hook tip of the rotating shuttle to hook the thread, the thread ring close to the front needle protection face can be protected by the groove, and the thread ring cannot be twisted or cannot be hooked by the hook tip of the rotating shuttle to cause thread breakage in the high-speed movement process.

Description

Technical Field

[0001] The utility model relates to the technical field of sewing machines, in particular to a rotary hook and lockstitch sewing machine. Background Art

[0002] The rotary hook of a sewing machine is composed of a bobbin frame, a bobbin core, a bobbin case and other structures. During the thread hooking process, the needle of the sewing machine needs to retract to relax the upper thread at the needle hole, so that a thread loop can be formed between the upper thread and the needle for the hook tip of the bobbin case to be inserted. As the bobbin case rotates, the thread loop expands to allow the entire bobbin frame to pass through and allow the upper thread and lower thread to be entangled.

[0003] Lockstitch sewing machines, such as template machines, require both forward and reverse sewing, meaning the fabric doesn't just move in a single direction. During the switchover between forward and reverse sewing, the upper thread rotates and easily accumulates a certain amount of torsional potential energy. This causes the upper thread to loosen and form loops that easily become entangled when the needle retracts. This can easily cause the hook tip of the bobbin case to simultaneously hook onto loops on both sides of the needle hole. Furthermore, the needle retracts and the bobbin case rotates, easily breaking the loops and causing the thread to break. Utility Model Content

[0004] Since the existing lockstitch sewing machine has the problem of easy thread breakage during the forward and reverse sewing process, it is necessary to provide a rotary shuttle and a lockstitch sewing machine.

[0005] A rotary hook for a lockstitch sewing machine, comprising:

[0006] a bobbin case assembly comprising a housing having a mounting cavity and a hook tip fixedly connected to the housing; and

[0007] A bobbin assembly, wherein the bobbin assembly is rotatably mounted in the mounting cavity of the housing, and the bobbin assembly has a first needle guard surface and a second needle guard surface spaced apart along the axial direction of the bobbin assembly, so as to form a clearance gap between the first needle guard surface and the second needle guard surface for avoiding the needle of the sewing machine, the first needle guard surface is arranged toward the hook tip, and the bobbin assembly also has a groove recessed from the first needle guard surface toward a direction away from the hook tip, for accommodating a thread loop located at the needle hole of the needle and facing the side of the first needle guard surface.

[0008] With this arrangement, when the needle descends to the lowest point with the upper thread, the upper thread is stuck in the groove. In this way, during the process of the needle rising to the point where the hook tip of the rotary shuttle hooks the thread, the thread loop near the front needle guard surface will be protected by the groove, so that the thread loop will not twist during high-speed movement or be hooked by the hook tip of the rotary shuttle, causing thread breakage, thereby reducing thread breakage. At the same time, the rotary shuttle has a significant effect on preventing thread breakage in reverse sewing of mercerized thread.

[0009] In one embodiment, the width of the groove gradually decreases in a direction approaching the axis of the bobbin assembly.

[0010] With this arrangement, the restriction of the groove on the thread loop on one side of the needle gradually weakens as the needle gradually retreats and rises. After the hook tip completely hooks the thread loop on the other side of the needle, the groove will not block the surface thread from exiting the groove and making way for the gap, and it also avoids thread breakage at the groove.

[0011] In one embodiment, the groove has two inner side walls that are opposite to each other, and both of the inner side walls extend along the radial direction of the bobbin assembly.

[0012] With such a configuration, the shape of the groove is fan-shaped, which corresponds to the swing of the bobbin assembly. In this way, even when the needle and the bobbin assembly abut between the two inner walls of the groove, the inclination angle between the needle and the two inner walls will not be too large, thereby avoiding bending of the needle.

[0013] In one embodiment, the width of the groove opening is greater than the width of the groove bottom.

[0014] This arrangement, on the one hand, makes it convenient for the wire loop on one side of the needle to enter the groove, and after the hook tip completes hooking the thread, the wire loop can also easily withdraw from the groove; on the other hand, the farther the wire loop is from the needle, the higher the degree of freedom. Since the bottom width of the groove is small, the groove can form a more effective restriction on the wire loop when the wire loop reaches the bottom of the groove.

[0015] In one embodiment, the edge of the groove and / or the inner edge of the groove are chamfered.

[0016] This arrangement can protect the upper thread and prevent it from being cut when entering and exiting the groove.

[0017] In one embodiment, the second needle guard surface is located on the outside of the bobbin assembly and is inclined to the axis of the bobbin assembly so as to face the needle of the sewing machine.

[0018] With this arrangement, due to the matching error between the bobbin core assembly and the bobbin case assembly, when there is an assembly error between the entire rotary hook and the needle, the needle can be guided by the second needle guard surface to prevent the needle from directly hitting the rotary hook, thereby protecting the needle and the rotary hook.

[0019] In one embodiment, the bobbin assembly includes a bobbin frame having a accommodating cavity and a bobbin core fixedly connected to the bobbin frame and located in the accommodating cavity, the clearance gap is located on the bobbin frame, and the bobbin core is provided with a clearance groove corresponding to the clearance gap.

[0020] This setting can avoid interference between the bobbin and the needle, ensure the normal operation of the sewing machine and protect the needle.

[0021] In one embodiment, the bobbin frame includes a mounting portion located in the mounting cavity and a needle guard portion located outside the mounting cavity, the needle guard portion extends radially from the mounting portion to form the first needle guard surface facing the hook tip, and the groove penetrates the needle guard portion radially along the bobbin frame and is connected to the clearance gap.

[0022] With this arrangement, the opening of the groove facilitates the adjustment of the needle position, so that the needle can enter the groove along the axial direction of the bobbin. Passing the groove through the needle guard can increase the space for the needle to move and avoid interference between the needle and the bobbin frame.

[0023] The present application also provides a lockstitch sewing machine, comprising a frame, a needle and a rotary hook as described above, wherein the rotary hook is fixedly connected to the frame, the needle is movably connected to the frame, and the piercing direction of the needle extends into the clearance gap.

[0024] In this way, the upper thread is protected by the hook with the groove, so that the upper thread can be kept stable in retreat during the repeated forward and reverse sewing process of the lockstitch sewing machine, thereby avoiding frequent thread breakage.

[0025] In one embodiment, the machine needle has a needle hole and a thread groove extending to the needle hole along the direction of piercing the material, and the thread groove is used to accommodate the upper thread.

[0026] With this setting, the upper thread is always confined in the thread groove and will not shake during the process of the needle penetrating the fabric and reaching the lowest point, thereby reducing the phenomenon of the upper thread wrapping around the needle. In the process of the needle retreating from the lowest point, it also prevents the upper thread close to the groove side from deflecting toward the hook tip, preventing thread breakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of a rotary hook and a needle in one embodiment of the present invention is shown;

[0028] Figure 2 for Figure 1 Schematic diagram of the hook tip hook line;

[0029] Figure 3 for Figure 2 A partial enlarged view of the middle needle at the needle hole;

[0030] Figure 4 for Figure 1 Schematic diagram of the structure of the bobbin case assembly;

[0031] Figure 5 for Figure 1 Schematic diagram of the structure of the middle bobbin frame;

[0032] Figure 6for Figure 5 Schematic diagram of the structure of the middle bobbin frame from another perspective;

[0033] Figure 7 for Figure 1 Schematic diagram of the structure of the middle bobbin core;

[0034] Figure 8 This is a partial enlarged view of the bobbin frame at the groove in another embodiment of the present invention;

[0035] Figure 9 This is a partial enlarged view of the bobbin frame at the groove in another embodiment of the present invention;

[0036] Figure 10 This is a partial enlarged view of the bobbin frame at the groove in another embodiment of the present invention.

[0037] Reference numerals:

[0038] 10. Bobbin case assembly; 11. Outer shell; 111. Mounting cavity; 112. Limiting groove; 12. Hook tip; 20. Bobbin assembly; 21. Bobbin frame; 211. Mounting portion; 2111. Limiting protrusion; 2112. Mounting shaft; 2113. Accommodating cavity; 212. Needle guard portion; 2121. First needle guard surface; 2122. Second needle guard surface; 2123. Clearance notch; 2124. Groove; 21241. Chamfer; 2125. Positioning groove; 22. Bobbin liner; 221. Bobbin case; 222. Inner liner; 223. Clearance groove; 224. Buckle; 30. Needle; 31. Needle hole; 32. Thread groove. DETAILED DESCRIPTION

[0039] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0042] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0043] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0044] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0045] The rotary hook of a sewing machine is composed of a bobbin frame, a bobbin core, a bobbin case and other structures. During the thread hooking process, the needle of the sewing machine needs to retract to relax the upper thread at the needle hole, so that a thread loop can be formed between the upper thread and the needle for the hook tip of the bobbin case to be inserted. As the bobbin case rotates, the thread loop expands to allow the entire bobbin frame to pass through and allow the upper thread and lower thread to be entangled.

[0046] Lockstitch sewing machines, such as template machines, require both forward and reverse sewing, meaning the fabric doesn't just move in a single direction. During the switchover between forward and reverse sewing, the upper thread rotates and easily accumulates a certain amount of torsional potential energy. This causes the upper thread to loosen and form loops that easily become entangled when the needle retracts. This can easily cause the hook tip of the bobbin case to simultaneously hook onto loops on both sides of the needle hole. Furthermore, the needle retracts and the bobbin case rotates, easily breaking the loops and causing the thread to break.

[0047] Based on the above problems, it is necessary to provide a rotary hook and lockstitch sewing machine.

[0048] See also Figures 1 to 7 , Figure 1 A schematic structural diagram of the rotary hook and the needle 30 in one embodiment of the present invention is shown; Figure 2 for Figure 1 Schematic diagram of the middle hook tip 12 hook line; Figure 3 for Figure 2 A partial enlarged view of the middle needle 30 at the needle hole 31; Figure 4 for Figure 1 A schematic structural diagram of the middle bobbin case assembly 10; Figure 5 for Figure 1 A schematic structural diagram of the middle bobbin frame 21; Figure 6 for Figure 5 A schematic structural diagram of the middle bobbin frame 21 from another perspective; Figure 7 for Figure 1 Schematic diagram of the structure of the middle bobbin core 22.

[0049] The rotary hook includes a bobbin case assembly 10 and a bobbin assembly 20. The bobbin case assembly 10 includes an outer shell 11 and a hook tip 12 fixedly connected to the bobbin case. The outer shell 11 has an installation cavity 111. The bobbin assembly 20 includes a bobbin frame 21 rotatably arranged in the installation cavity 111 and a bobbin liner 22 arranged in the bobbin frame 21. The bobbin liner 22 includes a bobbin case 221 and an inner liner 222 arranged in the bobbin case 221. The inner liner 222 is used for winding the bottom thread and is fixed in the bobbin case 221 by a buckle 224. The bobbin frame 21 is also provided with a mounting shaft 2112 for installing the bobbin liner 22.

[0050] A limiting protrusion 2111 is provided on the outer circumference of the bobbin frame 21, and a limiting groove cooperating with the limiting protrusion 2111 is provided in the outer shell 11 to enable the bobbin frame 21 and the outer shell 11 to rotate stably relative to each other. A positioning groove 2125 is also provided on the bobbin frame 21, and the positioning groove 2125 cooperates with the bobbin frame positioning hook fixed on the sewing machine to keep the bobbin frame 21 and the sewing machine relatively stationary.

[0051] The bobbin frame 21 has a first needle guard surface 2121 and a second needle guard surface 2122 arranged at axial intervals along the bobbin assembly 20, so as to form a clearance gap 2123 between the first needle guard surface 2121 and the second needle guard surface 2122 for avoiding the needle 30 of the sewing machine, and the first needle guard surface 2121 is arranged toward the hook tip 12.

[0052] In actual use, the bobbin assembly 20 in the above embodiment is stationary relative to the sewing machine, and the driving part of the sewing machine drives the bobbin case assembly 10 to rotate so that the hook tip 12 rotates to hook the thread. Before the needle 30 penetrates the fabric and reaches the lowest point, the upper thread is driven by the needle 30 into the clearance gap 2123 of the rotary hook. At this time, the needle 30 and the upper thread are tightly fitted; when the needle 30 retreats from the lowest point, the upper thread relaxes and forms two thread loops with the needle 30 on both sides of the needle hole 31 of the needle 30. The hook tip 12 of the rotary hook passes through the thread loop on the side close to the second needle guard surface 2122 and rotates further to expand the thread loop there and bypass the entire bobbin assembly 20 of the rotary hook, so that the upper thread and the lower thread are entangled. When the hook tip 12 rotates to the clearance gap 2123 again, the upper thread is released and is picked up and retracted by the thread picking mechanism of the sewing machine, thus completing a stitch.

[0053] See also Figure 5 and Figure 6In the rotary hook provided by the present invention, the bobbin frame 21 has a mounting portion 211 and a needle guard portion 212. The mounting portion 211 is located in the mounting cavity 111 of the outer shell 11. The needle guard portion 212 extends radially from the mounting portion 211 to form a first needle guard surface 2121 facing the hook tip 12. The present invention also provides a groove 2124 on the first needle guard surface 2121. The groove 2124 is recessed from the first needle guard surface 2121 toward the hook tip 12 and is used to accommodate a wire loop at the needle hole 31 of the machine needle 30 and close to the side of the first needle guard surface 2121. When the needle 30 descends to the lowest point with the upper thread, the upper thread is stuck in the groove 2124. In this way, during the process of the needle 30 rising to the hook tip 12 of the rotary shuttle to hook the thread, the thread loop near the front needle guard surface will be protected by the groove 2124, so that the thread loop will not be twisted during high-speed movement or hooked by the hook tip 12 of the rotary shuttle to cause thread breakage, thereby reducing thread breakage. At the same time, the rotary shuttle has a significant effect on avoiding the problem of thread breakage in reverse sewing of mercerized thread.

[0054] Furthermore, the groove 2124 penetrates the needle guard 212 in the radial direction of the bobbin frame 21 and is connected to the clearance notch 2123. The groove 2124 facilitates the adjustment of the position of the needle 30, allowing the needle 30 to enter the groove 2124 along the axial direction of the bobbin. The groove 2124 penetrating the needle guard 212 also increases the space for the needle 30 to move, thereby preventing interference between the needle 30 and the bobbin frame 21.

[0055] See also Figures 8 to 10 , Figures 8 to 10 They are respectively partial enlarged views of the bobbin frame 21 at the groove 2124 in three different embodiments of the present invention.

[0056] Preferably, in one embodiment of the present invention, the width of the groove 2124 gradually decreases along the direction close to the axis of the bobbin assembly 20, that is, Figure 8 The width A2 of the groove on both sides shown in the figure is smaller than A1. The restriction of the thread loop on one side of the needle 30 by the groove 2124 gradually weakens as the needle 30 gradually retreats and rises. After the hook tip 12 completely hooks the thread loop on the other side of the needle 30, the groove 2124 will not block the thread from exiting the groove 2124 and the clearance gap 2123, thus avoiding thread breakage at the groove 2124.

[0057] Alternatively, in one embodiment of the present invention, the groove 2124 has two inner sidewalls that are opposite to each other, and both inner sidewalls extend radially along the bobbin assembly 20. Thus, the groove 2124 is fan-shaped, which corresponds to the swinging motion of the bobbin assembly 20. Thus, even when the needle 30 abuts the bobbin assembly 20 between the two inner sidewalls at the groove 2124, the inclination angle between the needle 30 and the two inner sidewalls will not be too large, thereby preventing the needle 30 from bending.

[0058] Optionally, in one embodiment of the present invention, the notch width B2 of the groove 2124 is greater than the groove bottom width B2 of the groove 2124. Figure 9 On the one hand, this makes it easier for the thread loop on one side of the needle 30 to enter the groove 2124, and after the hook tip 12 has finished hooking the thread, the thread loop can also easily exit the groove 2124; on the other hand, the farther the thread loop is from the needle 30, the higher its degree of freedom. Since the groove bottom width of the groove 2124 is smaller, the groove 2124 can form a more effective restriction on the thread loop when the thread loop reaches the groove bottom of the groove 2124.

[0059] Preferably, in one embodiment of the present invention, the edge of the groove 2124 and / or the inner edge of the groove 2124 are both provided with chamfers 21241. This can protect the surface thread and prevent the surface thread from being cut when entering and exiting the groove 2124.

[0060] The above three embodiments can be combined, preferably as shown in the appended embodiment of the present invention. Figure 10 As shown in FIG, the notch width C3 at the lower end of the groove 2124 is smaller than the notch width C1 at the upper end of the groove, and the notch width C1 at the upper end of the groove 2124 is larger than the width C2 of the groove bottom.

[0061] Due to the matching error between the bobbin assembly and the bobbin case assembly, when there is an assembly error between the entire rotary hook and the needle, the tip of the needle is likely to directly hit the bobbin frame and break.

[0062] Specifically, in one embodiment of the present invention, the second needle guard surface 2122 is located outside the bobbin assembly 20 and is inclined relative to the axis of the bobbin assembly 20 so as to face the sewing machine needle 30. In this way, the needle 30 can be guided by the second needle guard surface 2122, preventing the needle 30 from directly striking the rotary hook, thereby protecting the needle 30 and the rotary hook.

[0063] Furthermore, the bobbin assembly 20 includes a bobbin frame 21 having a receiving cavity 2113, and a bobbin liner 22 fixedly connected to the bobbin frame 21 and positioned within the receiving cavity 2113. A clearance notch 2123 is located on the bobbin frame 21, and the bobbin liner 22 has a clearance groove 223 corresponding to the clearance notch 2123. The provision of the clearance groove 223 prevents interference between the bobbin liner 22 and the needle 30, thereby ensuring normal operation of the sewing machine and protecting the needle 30.

[0064] Please refer again Figure 1 The present application also provides a lockstitch sewing machine, including a frame (not shown), a needle 30 and a rotary hook as described above, wherein the rotary hook is fixedly connected to the frame, the needle 30 is movably connected to the frame, and the piercing direction of the needle 30 extends to the clearance gap 2123.

[0065] Specifically, the needle 30 has a needle hole 31 and a thread groove 32 extending from the needle hole 31 along the direction of penetration. The thread groove 32 is used to accommodate the upper thread. As the needle 30 penetrates the fabric and reaches its lowest point, the upper thread is always confined within the thread groove 32 and prevents it from swaying. This reduces the risk of the upper thread tangling around the needle 30. Furthermore, as the needle 30 retreats from its lowest point, the upper thread near the groove 2124 is prevented from deflecting toward the hook tip 12, preventing thread breakage.

[0066] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A rotary hook for a lockstitch sewing machine, characterized in that: include: A bobbin case assembly (10), the bobbin case assembly (10) comprising a housing (11) having a mounting cavity (111) and a hook tip (12) fixedly connected to the housing (11); and A bobbin assembly (20), wherein the bobbin assembly (20) is rotatably mounted in the mounting cavity (111) of the housing (11), and the bobbin assembly (20) has a first needle guard surface (2121) and a second needle guard surface (2122) which are spaced apart along the axial direction of the bobbin assembly (20), so as to form a clearance gap (2123) between the first needle guard surface (2121) and the second needle guard surface (2122) for avoiding a needle (30) of the sewing machine, wherein the first needle guard surface (2121) is arranged toward the hook tip (12), and the bobbin assembly (20) also has a groove (2124) which is recessed from the first needle guard surface (2121) toward a direction away from the hook tip (12), and is used to accommodate a thread loop located at the needle hole (31) of the needle (30) and toward the first needle guard surface (2121).

2. A rotary hook according to claim 1, characterized in that: The width of the groove (2124) gradually decreases along a direction approaching the axis of the bobbin assembly (20).

3. A rotary hook according to claim 2, characterized in that: The groove (2124) has two inner side walls that are arranged opposite to each other, and both of the inner side walls extend along the radial direction of the bobbin assembly (20).

4. A rotary hook according to claim 2, characterized in that: The slot width of the groove (2124) is greater than the slot bottom width of the groove (2124).

5. A rotary hook according to claim 2, characterized in that: The edge of the groove (2124) and / or the inner edge of the groove (2124) are both provided with chamfers (21241).

6. A rotary hook according to claim 1, characterized in that: The second needle protection surface (2122) is located on the outside of the bobbin assembly (20) and is inclined to the axis of the bobbin assembly (20) so as to face the needle (30) of the sewing machine.

7. A rotary hook according to any one of claims 1 to 6, characterized in that: The bobbin assembly (20) comprises a bobbin frame (21) having a receiving cavity (2113) and a bobbin core (22) fixedly connected to the bobbin frame (21) and located in the receiving cavity (2113); the clearance notch (2123) is located in the bobbin frame (21); and the bobbin core (22) is provided with a clearance groove (223) corresponding to the clearance notch (2123).

8. A rotary hook according to claim 7, characterized in that: The bobbin frame (21) includes a mounting portion (211) located in the mounting cavity (111) and a needle guard portion (212) located outside the mounting cavity (111), the needle guard portion (212) radially extending from the mounting portion (211) to form the first needle guard surface (2121) facing the hook tip (12), and the groove (2124) penetrates the needle guard portion (212) along the radial direction of the bobbin frame (21) and is connected to the clearance gap (2123).

9. A lockstitch sewing machine, characterized in that: It comprises a machine frame, a machine needle (30) and a rotary shuttle as described in any one of claims 1 to 8, wherein the rotary shuttle is fixedly connected to the machine frame, the machine needle (30) is movably connected to the machine frame, and the piercing direction of the machine needle (30) extends into the clearance gap (2123).

10. A lockstitch sewing machine according to claim 9, characterized in that: The machine needle (30) comprises a needle hole (31) and a thread groove (32) extending to the needle hole (31) along a piercing direction, and the thread groove (32) is used for accommodating an upper thread.

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