Thread pulling mechanism of sewing machine

Abstract

The present invention relates to a thread pulling mechanism of a sewing machine. The thread pulling mechanism comprises a rotary-hook base, a rotary hook, a rotary-hook shaft and a main driving shaft, wherein the bottom of the rotary hook is arranged on the top of the rotary-hook base; the rotary-hook shaft passes through the rotary-hook base, has an upper end thereof connected to the bottom of the rotary hook at the top of the rotary-hook base, and drives the rotary hook to rotate around a vertical axis; a smaller conical gear is provided at the lower end of the rotary-hook shaft, and the smaller conical gear meshes with a larger conical gear of the main driving shaft; and the rotary-hook base is also provided with a thread pulling hook and a pulling rod which cooperate with the rotary hook, the pulling rod driving the thread pulling hook to swing. The present invention has a simple structure, the swinging of the thread pulling hook no longer depends on the elastic force of a spring, and when the rotary hook still rotates twice, the thread pulling hook only swings once, thus solving the problem in the prior art of the unstable distance between the thread pulling hook and the rotary hook caused by the readily changing elasticity of the spring and the complicated structure of a bobbin case lifter.

Description

Thread pulling mechanism of a sewing machine Technical Field

[0001] The invention relates to the technical field of sewing machines, in particular to a thread pulling mechanism of a sewing machine. Background Art

[0002] Chinese Patent CN101413188B, "Sewing Machine and Hook System Thereof," discloses a hook system (thread pulling system) comprising a hook driven by a hook drive shaft, a control plate with a control curve, a bobbin case, and a bobbin case lifter. The bobbin case includes a lifting cam on its upper edge, which projects outward substantially radially from the axis and engages with a lifting rod (thread pulling hook). The lifting rod forms the arm of the bobbin case lifter. The bobbin case lifter serves as a support for the lifting rod and is designed as a double-armed lever that is substantially perpendicular, i.e., parallel to the axis. The bobbin case lifter includes a lifter shaft formed by a bolt, mounted in a column about an axis perpendicular to the axis, and loaded by a return spring. The lifter shaft of the bobbin case lifter is mounted in a bearing formed in the column that serves as the hook support housing. A sensor formed by a rod is attached to the bobbin case lifter below the lifter shaft. An annular control disc is mounted on the hook drive shaft. This disc includes a control curve on its outer circumference, against which the sensor is supported by the return force of a return spring. The control curve extends in a closed pattern across the entire circumference of the disc and has a varying radial distance from the axis. This allows the lifting rod to undergo reciprocating pivoting motion during one rotation of the hook drive shaft, and therefore the hook. The control disc includes a fixing ring that is mounted to the hook drive shaft via a clamping screw.

[0003] The hook drive shaft, which drives the hook and can also be driven by the red axis, is also mounted in a helical gear. This helical gear is mounted on the base plate and is conventionally designed as a bevel gear. The hook drive shaft is driven by this reduction helical gear via a transmission shaft. The transmission shaft is driven by the arm shaft via a synchronous belt transmission device with a transmission ratio of 1:1. The transmission ratio of the helical gear is 1:2, which means that for every rotation of the arm shaft or transmission shaft, the hook rotates twice.

[0004] The patented design suffers from a limited spring lifespan, resulting in an unstable spacing between the lifter and the cam over time. This is due to the helical gear's 1:2 transmission ratio. For every rotation of the drive shaft, the hook rotates twice, and the lifter pivots twice. However, the hook only hooks the thread once during these two rotations, and the lifter pivots meaningfully only during this time; the other rotation is idle. The lifter's pivoting is dependent on the rotation of the annular control disk on the hook's drive shaft and the expansion and contraction of the return spring. With each rotation of the bobbin case, the lifter pivots once, and the return spring expands and contracts once. Half of this expansion and contraction is meaningless, and the return spring's frequent state changes also cause changes in elasticity, affecting the coordination between the lifter and the cam. Furthermore, the entire bobbin case lifter structure is overly complex, with numerous connecting components and numerous potential errors. Summary of the Invention

[0005] The object of the present invention is to provide a thread pulling mechanism for a sewing machine, which has a simple structure and in which the swing of the thread pulling hook no longer depends on the elastic force of a spring. When the rotary hook still rotates twice, the thread pulling hook only swings once, thereby solving the problem in the prior art that the distance between the thread pulling hook and the rotary hook is unstable due to the elastic change of the spring and the complex structure of the shuttle case lifter.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A thread pulling mechanism for a sewing machine includes a hook seat, a hook, a hook shaft, and a main drive shaft. The bottom of the hook is arranged on the top of the hook seat. The hook shaft is inserted into the hook seat. The upper end of the hook shaft is connected to the bottom of the hook at the top of the hook seat and drives the hook to rotate around a vertical axis. A conical pinion is provided at the lower end of the hook shaft, which meshes with a conical gear of the main drive shaft. A thread pulling hook and a pulling rod that cooperate with the hook are also provided on the hook seat. The pulling rod drives the thread pulling hook to swing.

[0008] The main driving shaft is also provided with a pulling wheel, and a curved groove is provided circumferentially on the surface of the pulling wheel; the lower end of the pulling rod is arranged in the curved groove, and the pulling rod swings with the rotation of the pulling wheel, thereby driving the wire pulling hook to swing.

[0009] The thread pulling hook comprises an upper thread hook, an axis hole and a lower hook handle. The thread pulling hook is arranged on the rotary hook seat through the axis hole, and the thread hook cooperates with the rotary hook.

[0010] The pulling rod includes an upper swing arm, a rod body and a lower swing arm, the upper end of the rod body is connected to the upper swing arm, and the lower end of the rod body is connected to the lower swing arm;

[0011] The upper swing arm drives the wire pulling hook to swing, and the lower swing arm is arranged in the curved groove of the pulling wheel.

[0012] The curved groove is a regular closed-loop groove extending from left to right and then to left.

[0013] The hook handle is provided with a slot with an opening at the lower end, and the upper swing arm is clipped into the slot;

[0014] The rotation of the pulling wheel causes the lower swing arm to periodically move from left to right and then to left in the curved groove, thereby causing the upper swing arm to drive the hook handle to swing left and right periodically.

[0015] The transmission ratio of the bevel gear to the bevel gear is 2:1.

[0016] The pulling wheel rotates with the main driving shaft, and the pulling wheel rotates one circle to drive the wire pulling hook to swing to the left once.

[0017] The rotary hook shaft is arranged in parallel with the pulling rod.

[0018] The advantages of the present invention are: 1. The pulling wheel rotates with the main drive shaft, that is, the rotary hook rotates twice, and the thread pulling hook only swings to the left once when the rotary hook hooks the thread; 2. The distance between the thread pulling hook and the rotary hook no longer uses a spring that is very prone to error. Instead, a curved groove and a mechanical lever of the pulling rod are used to cooperate, which not only reduces the error but also ensures the stable swing of the thread pulling hook. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic diagram of the present invention.

[0020] FIG2 is a cross-sectional view of the present invention.

[0021] FIG3 is a schematic structural diagram of the pulling wheel of the present invention.

[0022] FIG4 is a schematic diagram of the wire hook of the puller structure of the present invention in the starting position.

[0023] FIG5 is a schematic diagram of the wire hook of the puller structure of the present invention swinging to the left position.

[0024] In the figure: 1-hook seat; 2-hook; 3-hook shaft; 31-conical small gear; 4-main drive shaft; 41-conical large gear; 42-pulling wheel; 43-curved groove; 5-thread pulling hook; 51-thread hook; 52-axis hole; 53-hook handle; 6-pulling rod; 61-rod body; 62-upper swing arm; 63-lower swing arm. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings, which are for illustrative purposes only and are not to be construed as limiting the present invention.

[0026] To more concisely illustrate this embodiment, some components well known to those skilled in the art but not relevant to the main content of this invention may be omitted from the drawings or descriptions. In addition, for ease of description, some components may be omitted, enlarged, or reduced in size in the drawings, but they do not represent the dimensions or entire structure of the actual product.

[0027] A thread pulling mechanism of a sewing machine of the present invention, as shown in Figures 1 and 2, includes a hook seat 1, a hook 2, a hook shaft 3, and a main drive shaft 4. The bottom of the hook 2 is arranged on the top of the hook seat 1, and the hook shaft 3 is passed through the hook seat 1. The upper end of the hook shaft 3 is connected to the bottom of the hook 2 at the top of the hook seat 1 and drives the hook 2 to rotate around the vertical axis. A conical pinion 31 is provided at the lower end of the hook shaft 3, and the conical pinion 31 is engaged with the conical gear 41 of the main drive shaft.

[0028] Preferably, the transmission ratio of the conical large gear 41 to the conical small gear 31 is 2:1, that is, when the main drive shaft 4 rotates one circle, the conical large gear 41 on it drives the rotary hook shaft 3 connected to the conical small gear 31 to rotate two circles, that is, the rotary hook shaft 3 also drives the rotary hook 2 to rotate two circles, which is the same as the existing technology.

[0029] The rotary hook seat 1 is also provided with a thread pulling hook 5 and a pulling rod 6 that cooperate with the rotary hook 2. The pulling rod 6 drives the thread pulling hook 5 to swing;

[0030] Further, as shown in Figures 1, 4 and 5, the thread pulling hook 5 includes an upper thread hook 51, an axial hole 52 and a lower hook handle 53. The thread pulling hook 5 is set on the shuttle seat 1 through the axial hole 52. The thread pulling hook 5 can rotate with the axial hole 52 as the axis, and the thread hook 51 thereon can cooperate with the shuttle 2 to swing left and right.

[0031] As shown in FIG. 2 and FIG. 3 , the pulling rod 6 provided on the rotary hook seat 1 is provided parallel to the rotary hook shaft 3 .

[0032] The pulling rod 6 includes an upper swing arm 62 , a rod body 61 and a lower swing arm 63 . The upper end of the rod body 61 is connected to the upper swing arm 62 , and the lower end of the rod body 61 is connected to the lower swing arm 63 .

[0033] As shown in Figures 2 and 3, the main drive shaft 4 is also provided with a pulling wheel 42. When the main drive shaft 4 rotates one circle, the pulling wheel 42 rotates one circle accordingly. A curved groove 43 is provided circumferentially on the surface of the pulling wheel 42; the lower swing arm 63 of the pulling rod 6 is provided in the curved groove 43, and the pulling rod 6 swings periodically with the rotation of the pulling wheel 42.

[0034] Preferably, the curved groove 43 is a regular groove in a closed loop from left to right and then to left (i.e., a regular curved groove). In this way, as the pulling wheel 42 rotates, the lower swing arm 63 performs regular movement under the guidance of the groove wall of the curved groove 43. As shown in Figures 4 and 5, when the lower swing arm 63 gradually slides from the rightmost end of the curve to the leftmost end of the curve in the curved groove 43, the rod body 61 and the upper swing arm 62 gradually swing to the right end, thereby driving the wire hook 51 to swing to the left; when the lower swing arm 63 gradually slides from the leftmost end of the curve to the rightmost end of the curve in the curved groove 43, the rod body 61 and the upper swing arm 62 gradually swing to the left end, thereby driving the wire hook 51 to swing to the right to its original position.

[0035] The pulling wheel 42 rotates along with the main driving shaft 4, and the rotation of the pulling wheel 42 drives the pulling rod 6 to swing. When the pulling wheel 42 rotates one circle, the wire pulling hook 5 swings leftward once.

[0036] Furthermore, an open slot is provided at the lower end of the hook handle 53, and the upper swing arm 62 is inserted into the slot, which is convenient for installation and stability adjustment.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. That is, any equivalent changes and modifications made according to the content of the patent application of the present invention should fall within the technical scope of the present invention.

Claims

1. A thread pulling mechanism of a sewing machine, comprising a rotary hook seat (1), a rotary hook (2), a rotary hook shaft (3) and a main drive shaft (4), wherein the bottom of the rotary hook (2) is arranged on the top of the rotary hook seat (1), the rotary hook shaft (3) is inserted into the rotary hook seat (1), and the upper end of the rotary hook shaft (3) is connected to the bottom of the rotary hook (2) at the top of the rotary hook seat (1), and drives the rotary hook (2) to rotate around a vertical axis; a conical pinion (31) is arranged at the lower end of the rotary hook shaft (3), and the conical pinion (31) is meshed with a conical gear (41) of the main drive shaft (4); a thread pulling hook (5) and a pulling rod (6) which cooperate with the rotary hook (2) are also arranged on the rotary hook seat (1), and the pulling rod (6) drives the thread pulling hook (5) to swing; Features: The main drive shaft (4) is further provided with a pulling wheel (42), and a curved groove (43) is circumferentially provided on the surface of the pulling wheel (42); the lower end of the pulling rod (6) is arranged in the curved groove (43), and the pulling rod (6) swings with the rotation of the pulling wheel (42), thereby driving the wire pulling hook (5) to swing.

2. The thread pulling mechanism of a sewing machine according to claim 1, characterized in that: The thread pulling hook (5) comprises an upper thread hook (51), an axial hole (52) and a lower hook handle (53); the thread pulling hook (5) is arranged on the rotary shuttle seat (1) through the axial hole (52); the thread hook (51) cooperates with the rotary shuttle (2); The pulling rod (6) comprises an upper swing arm (62), a rod body (61) and a lower swing arm (63), wherein the upper end of the rod body (61) is connected to the upper swing arm (62), and the lower end of the rod body (61) is connected to the lower swing arm (63); The upper swing arm (62) drives the wire pulling hook (5) to swing, and the lower swing arm (63) is arranged in the curved groove (43) of the pulling wheel (42).

3. The thread pulling mechanism of a sewing machine according to claim 2, characterized in that: The curved groove (43) is a regular closed-loop groove extending from left to right and then to left.

4. The thread pulling mechanism of a sewing machine according to claim 3, characterized in that: The hook handle (53) is provided with a slot with an opening at the lower end, and the upper swing arm (62) is inserted into the slot; The pull wheel (42) rotates to cause the lower swing arm (63) to periodically move from left to right and then to left in the curved groove (43), thereby causing the upper swing arm (62) to drive the hook handle (53) to periodically swing left and right.

5. The thread pulling mechanism of a sewing machine according to claim 1, characterized in that: The transmission ratio between the conical gear (41) and the conical gear (31) is 2:

1.

6. The thread pulling mechanism of a sewing machine according to claim 1, characterized in that: The pulling wheel (42) rotates with the main drive shaft (4), and the pulling wheel (42) rotates one circle to drive the wire pulling hook (5) to swing leftward once.

7. The thread pulling mechanism of a sewing machine according to claim 1, characterized in that: The rotary hook shaft (3) and the pulling rod (6) are arranged in parallel.

Images