Step adjustment feed mechanism for sewing machine

Abstract

The invention belongs to the technical field of sewing equipment, and relates to a step adjustment cloth feeding mechanism of a sewing machine, which comprises a rotary driving source, which synchronously drives two mechanically coupled adjustment paths: one controls a differential ratio through a cam transmission part on a first transmission gear, and the other controls a stitch length through an eccentric transmission feature on a second transmission gear; a plurality of different equal-radius arc surface segments are arranged on the cam transmission part, and a second gear transmission part of the second transmission gear is engaged with a first gear transmission part of the first transmission gear in the form of a speed-up transmission ratio; wherein, when the stitch length is adjusted, the cam transmission part keeps running on the same equal-radius arc surface segment; when the differential ratio is adjusted, the net adjustment amount of the eccentric transmission feature on the stitch length is zero. The step adjustment cloth feeding mechanism of the sewing machine provided by the invention can independently adjust the stitch length and the differential ratio of the cloth feeding mechanism during the sewing process, and has the characteristics of compact structure, simple control and high adjustment precision.

Description

Technical Field

[0001] This invention belongs to the technical field of sewing equipment, and relates to a stepping adjustment fabric feeding mechanism for a sewing machine. Background Technology

[0002] Currently, sewing machines require adjustments to their stitch length and differential ratio when sewing different fabrics or performing different processes. Several existing technologies already exist that enable automatic adjustment of stitch length and differential ratio.

[0003] For example, Chinese invention patent CN117904803A (publication date: April 19, 2024) discloses a sewing machine with adjustable stitch length and differential ratio, and a sewing machine adjustment method. The sewing machine includes a main shaft, a main feed dog, a main feed tooth, a differential feed dog, a differential feed tooth, a main feed mechanism, a differential feed mechanism, an adjustment drive source, a main feed adjustment gear driven by the adjustment drive source, a differential feed adjustment gear connected to the main feed adjustment gear, and a differential feed adjustment unit. The main feed adjustment gear is coaxially fixed with the main feed transmission component, and the differential feed adjustment unit is connected between the differential feed adjustment gear and the differential feed transmission component. The differential feed adjustment gear has N teeth, and the main feed adjustment gear has n*N+1 teeth.

[0004] Its drawback lies in the strong coupling between stitch length adjustment and differential ratio adjustment. When stitch length adjustment is required independently, the non-full rotation of the main feed adjustment gear inevitably causes the differential feed adjustment gear to rotate unexpectedly, resulting in an unexpected change in the differential ratio. Although the differential ratio can be restored to its original value through a subsequent "return" step, this "deviate first, then return" control method increases the complexity of the control system and cannot achieve truly independent real-time adjustment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a step-adjustable feeding mechanism for a sewing machine, which can independently adjust the stitch length and differential ratio of the feeding mechanism during sewing. It also features a compact structure, simple control, and high adjustment precision.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A step-adjustable fabric feeding mechanism for a sewing machine includes a rotary drive source that synchronously drives two mechanically coupled adjustment paths: one controls the differential ratio through a cam drive on a first transmission gear, and the other controls the stitch length through an eccentric drive feature on a second transmission gear; the cam drive is provided with multiple arc segments of different equal radii, and the second gear drive of the second transmission gear meshes with the first gear drive of the first transmission gear in a manner that increases the transmission ratio;

[0008] When adjusting the stitch length, the cam drive unit operates on the same equal radius arc segment; when adjusting the differential ratio, the cam drive unit switches to another equal radius arc segment, and during this process, the rotation angle of the second transmission gear and the rotation angle of the first transmission gear always maintain a predetermined proportional relationship, so that after the equal radius arc segment on the cam drive unit is switched, the net adjustment amount of the eccentric transmission feature on the stitch length is zero.

[0009] As a further improvement of the present invention, the first transmission gear rotates at the same angle each time it switches to the next equal radius arc segment.

[0010] As a further improvement of the present invention, for every fixed angle by which the first transmission gear rotates to switch the arc surface segment of equal radius, the second transmission gear rotates synchronously by an angle that is an integer multiple of its own rotation of 180 degrees.

[0011] As a further improvement of the present invention, the number of equal radius arc segments is at least 6, and the transmission ratio between the first transmission gear and the second transmission gear is not greater than 1:3.

[0012] As a further improvement of the present invention, the radius of the equal-radius arc segment changes monotonically along the rotation direction, and adjacent equal-radius arc segments are smoothly connected by a transition segment.

[0013] As a further improvement of the present invention, the cam transmission unit is connected to the differential ratio adjustment component via a differential ratio adjustment transmission component; the eccentric transmission feature is connected to the needle pitch adjustment component via a needle pitch adjustment transmission component.

[0014] As a further improvement of the present invention, the differential ratio adjustment transmission assembly includes:

[0015] The differential ratio adjusting link has one end abutting against the contour of the cam drive unit;

[0016] A rolling element that abuts against the other end of the differential ratio adjusting link;

[0017] The oscillating crank has one end connected to the rolling element and the other end connected to the differential ratio adjustment assembly.

[0018] As a further improvement of the present invention, the needle pitch adjustment transmission assembly includes:

[0019] A needle pitch adjusting linkage, one end of which is hinged to the eccentric transmission feature;

[0020] The crank is adjusted such that one end is hinged to the other end of the stitch pitch adjustment linkage, and the other end is connected to the angle adjustment linkage of the stitch pitch adjustment assembly.

[0021] The second transmission gear rotates once, driving the angle adjustment linkage to complete two cycles of oscillation.

[0022] The present invention also provides a sewing machine comprising any of the above-described fabric feeding mechanisms.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This invention provides a step-adjustable feed mechanism for a sewing machine, achieving completely independent real-time adjustment of stitch length and differential ratio. This invention achieves complete decoupling of stitch length and differential ratio in a mechanically coupled single-power-source feed mechanism. When adjusting the stitch length, the cam drive unit remains within the same equal-radius arc segment, and the differential ratio remains locked. When adjusting the differential ratio, through precise kinematic matching, the rotation angle of the second transmission gear is an integer multiple of 180 degrees, and the net adjustment of the eccentric transmission feature on the stitch length is zero, thus keeping the stitch length constant.

[0025] 2. The stitch length of this invention achieves continuous stepless adjustment, and the differential ratio enables precise switching between multiple levels. In this invention, the stitch length is continuously determined by the rotation angle of the second transmission gear, and in conjunction with a stepper motor, high-precision stepless adjustment can be achieved. The differential ratio is determined by the equal-radius arc segment on the cam transmission unit. Each equal-radius arc segment corresponds to a stable differential ratio output level. Precise switching of the differential ratio level is achieved by switching the arc segment, resulting in high repeatability. Furthermore, this invention requires no machine stoppage, no waiting for a specific phase, and no manual intervention during adjustment, greatly improving production efficiency. Attached Figure Description

[0026] Figure 1 This is a perspective view of the sewing machine of the present invention.

[0027] Figure 2 This is a perspective view of the step-adjustable fabric feeding mechanism of the present invention;

[0028] Figure 3 This is an exploded view of the differential ratio adjustment structure of the present invention;

[0029] Figure 4 This is an exploded view of the needle spacing adjustment structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the gear assembly of the present invention;

[0031] In the diagram: 1. Rotation drive source;

[0032] 2. First transmission gear; 21. Cam transmission unit; 211. Equal radius arc surface section; 212. Transition section; 22. First gear transmission unit;

[0033] 3. Second transmission gear; 31. Eccentric transmission characteristics; 32. Second gear transmission unit;

[0034] 4. Differential ratio adjustment transmission assembly; 41. Differential ratio adjustment linkage; 42. Rolling element; 43. Oscillating crank; 44. Return spring;

[0035] 5. Differential ratio adjustment component;

[0036] 6. Stitch pitch adjustment transmission assembly; 61. Stitch pitch adjustment linkage; 62. Adjustment crank;

[0037] 7. Stitch pitch adjustment assembly; 71. Angle adjustment linkage;

[0038] 8. Motor mounting plate; 81. Pin shaft. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] Comparison Appendix Figure 2 This embodiment provides a step-adjustable fabric feeding mechanism for a sewing machine, including a rotary drive source 1, a first transmission gear 2, a second transmission gear 3, a differential ratio adjustment transmission component 4, a differential ratio adjustment component 5, a stitch length adjustment transmission component 6, and a stitch length adjustment component 7.

[0042] The rotary drive source 1 is fixedly mounted on the motor mounting plate 8. In this embodiment, the rotary drive source 1 is a stepper motor to achieve precise angle control. The first transmission gear 2 is coaxially fixed with the output shaft of the rotary drive source 1 and is directly driven by the rotary drive source 1. The second transmission gear 3 is hinged to the motor mounting plate 8 via a pin 81 and meshes with the first transmission gear 2. In this embodiment, the transmission ratio between the first transmission gear 2 and the second transmission gear 3 is set to no more than 1:3, that is, the rotational speed of the second transmission gear 3 is more than 3 times that of the first transmission gear 2, thereby achieving speed-increasing transmission.

[0043] As shown in the figure, the first transmission gear 2 integrates a first gear transmission part 22 and a cam transmission part 21. The first gear transmission part 22 is used to mesh with the second gear transmission part 32 of the second transmission gear 3 to transmit power; the cam transmission part 21 is a disc-shaped cam that is coaxially fixed with the first transmission gear 2, and its working profile abuts against the differential ratio adjusting linkage 41 of the differential ratio adjusting transmission assembly 4. The working profile of the cam transmission part 21 is as follows. Figure 5As shown, it is provided with 11 arc surface segments 211 of equal radius. Each arc surface segment 211 is a circular arc with a constant radius. The radius values ​​of the 11 arc surface segments 211 are different and are marked as r1-r11 respectively, and they increase sequentially along the rotation direction of the first transmission gear 2, that is, r1 increases sequentially to r11. Adjacent arc surface segments 211 are smoothly connected by transition segments 212. The contour curve of the transition segment 212 is a continuously differentiable curve to ensure the smoothness of the differential ratio adjusting linkage 41 when sliding on the surface of the cam transmission part 21.

[0044] The second transmission gear 3 integrates a second gear transmission part 32 and an eccentric transmission feature 31. The second gear transmission part 32 is used to mesh with the first gear transmission part 22 of the first transmission gear 2; the eccentric transmission feature 31 is a cylindrical pin that is offset from the rotation center of the second transmission gear 3.

[0045] Each time the system switches to the next equal-radius arc segment 211, the first transmission gear 2 rotates at the same angle. Furthermore, for every fixed angle that the first transmission gear 2 rotates to switch the equal-radius arc segment 211, the second transmission gear 3 rotates synchronously by an angle that is an integer multiple of its own rotation of 180 degrees.

[0046] Comparison Appendix Figure 3 In this embodiment, the specific structures of the differential ratio adjusting transmission assembly 4 and the differential ratio adjusting assembly 5 are as follows:

[0047] As shown in the figure, the differential ratio adjustment transmission assembly 4 includes a differential ratio adjustment link 41, a rolling element 42, a swing crank 43, and a return spring 44.

[0048] The differential ratio adjusting rod 41 is hinged to the pin 81 and can swing around the pin 81. The first end of the differential ratio adjusting rod 41 abuts against the working contour of the cam drive unit 21, and under the action of the return spring 44, this end always maintains contact with the working contour of the cam drive unit 21. The second end of the differential ratio adjusting rod 41 abuts against a rolling element 42. In this embodiment, the rolling element 42 is a needle roller bearing to reduce frictional resistance.

[0049] One end of the swing crank 43 is connected to the rolling element 42, and the other end is connected to the input end of the differential ratio adjustment component 5. When the differential ratio adjustment linkage 41 swings with the working profile of the cam drive unit 21, its second end pushes the swing crank 43 to swing through the rolling element 42, thereby driving the differential ratio adjustment component 5 to work and change the feed differential ratio.

[0050] One end of the return spring 44 is connected to the differential ratio adjusting link 41, and the other end is connected to the motor mounting plate 8. It provides the differential ratio adjusting link 41 with a preload that always faces the cam drive unit 21, ensuring reliable contact between the differential ratio adjusting link 41 and the working contour of the cam drive unit 21.

[0051] The differential ratio adjustment component 5 is a conventional mechanism used in sewing machines to change the differential ratio. Its specific structure is not the focus of this invention and will not be described in detail here.

[0052] Comparison Appendix Figure 4 In this embodiment, the specific structures of the stitch pitch adjustment transmission assembly 6 and the stitch pitch adjustment assembly 7 are as follows:

[0053] As shown in the figure, the stitch pitch adjustment transmission assembly 6 includes a stitch pitch adjustment linkage 61 and an adjustment crank 62.

[0054] The first end of the stitch pitch adjusting linkage 61 is hinged to the eccentric transmission feature 31 of the second transmission gear 3. The second end of the stitch pitch adjusting linkage 61 is hinged to one end of the adjusting crank 62. The other end of the adjusting crank 62 is connected to the angle adjusting linkage 71 of the stitch pitch adjusting assembly 7.

[0055] The stitch length adjustment component 7 is a conventional mechanism in a sewing machine used to change the stitch length. Its specific structure is not the focus of this invention and will not be described in detail here.

[0056] When the second transmission gear 3 rotates, its eccentric transmission feature 31 performs circular motion, driving the adjusting crank 62 to swing via the stitch pitch adjusting linkage 61, which in turn drives the angle adjusting linkage 71 to swing, thus achieving stitch pitch adjustment. In this embodiment, for each rotation of the second transmission gear 3, the eccentric transmission feature 31 drives the adjusting crank 62 to complete two cycles of swinging, that is, the angle adjusting linkage 71 swings back and forth twice. This characteristic is determined by the kinematics of the crank-rocker mechanism formed by the eccentric transmission feature 31, the stitch pitch adjusting linkage 61, and the adjusting crank 62.

[0057] The principle of independently adjusting the differential ratio in this embodiment is:

[0058] The differential ratio is determined by the working profile position of the cam drive unit 21. When the cam drive unit 21 runs on a certain arc surface segment 211 with equal radius, the position of the differential ratio adjusting linkage 41 remains constant, the swing amplitude of the swing crank 43 remains constant, and the output state (i.e., differential ratio) of the differential ratio adjusting component 5 remains constant.

[0059] When switching the differential ratio, the rotary drive source 1 drives the first transmission gear 2 to rotate, causing its cam transmission section 21 to switch from one equal-radius arc surface segment 211 to another equal-radius arc surface segment 211. During this process, the position of the differential ratio adjusting linkage 41 changes with the working contour of the cam transmission section 21, and pushes the swing crank 43 to swing to the new position through the rolling element 42, thereby driving the differential ratio adjusting assembly 5 to output a new differential ratio.

[0060] Since the radius values ​​of each equal-radius arc segment 211 are different, and each arc segment corresponds to a stable differential ratio output position, the present invention can achieve precise switching between multiple preset differential ratio levels. In this embodiment, the 11 equal-radius arc segments 211 correspond to 11 different differential ratio levels.

[0061] When the differential ratio is switched, the rotary drive source 1 is controlled to drive the first transmission gear 2 to rotate by a fixed angle, so that its cam transmission part 21 switches from the current equal radius arc surface segment 211 to the next equal radius arc surface segment 211.

[0062] During this process, the second transmission gear 3 is driven to rotate in multiples of 180 degrees through meshing. Since the second transmission gear 3 rotates 180 degrees, its eccentric transmission feature 31 drives the angle adjustment linkage 71 to complete a full cycle and return to the initial position. Therefore, during this switching process, the net adjustment of the needle pitch by the eccentric transmission feature 31 is zero, and the needle pitch remains unchanged.

[0063] If multiple differential ratio settings need to be adjusted continuously, simply repeat the above fixed-angle stepping action. With each step, the cam drive unit 21 switches to a constant radius arc segment 211, the differential ratio changes by one setting, and at the same time, the second transmission gear 3 rotates by an integer multiple of 180 degrees. The needle pitch returns precisely to the original value after each step.

[0064] The principle behind the independent adjustment of stitch length in this embodiment is:

[0065] A rotary drive source 1 drives the first transmission gear 2 to rotate. The first gear transmission part 22 of the first transmission gear 2 drives the second transmission gear 3 to rotate through the meshing second gear transmission part 32, thereby realizing the adjustment of the stitch pitch. The stitch pitch is determined by the rotation angle of the second transmission gear 3. When the second transmission gear 3 rotates, its eccentric transmission feature 31 drives the angle adjustment linkage 71 to swing through the stitch pitch adjustment transmission assembly 6. The swing amplitude of the angle adjustment linkage 71 is positively correlated with the rotation angle of the second transmission gear 3, and the relationship is continuous.

[0066] During the needle pitch adjustment process, the rotary drive source 1 is controlled to drive the first transmission gear 2 to reciprocate within its current equal radius arc segment 211, without crossing to other equal radius arc segments 211. Since the cam transmission unit 21 always operates on the same equal radius arc segment 211, the position of the differential ratio adjustment linkage 41 remains constant, and the differential ratio is locked at the current gear.

[0067] Since the second transmission gear 3 rotates 180 degrees, its eccentric transmission feature 31 drives the angle adjustment linkage 71 to complete a full cycle and return to the initial position, when the first transmission gear 2 reciprocates within the current equal radius arc segment 211, the stitch pitch can be continuously and steplessly adjusted, and the adjustment range completely covers the stitch pitch range allowed under the differential ratio gear.

[0068] Example 2

[0069] This embodiment provides a sewing machine whose feeding mechanism adopts the step-adjustable feeding mechanism of Embodiment 1. This sewing machine can steplessly adjust the stitch length or switch differential ratios during sewing operations, and the differential ratio remains constant during stitch length adjustment, while the stitch length remains unchanged during differential ratio adjustment.

[0070] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A step-adjustable fabric feeding mechanism for a sewing machine, characterized in that, It includes a rotary drive source (1), which synchronously drives two mechanically coupled adjustment paths: one controls the differential ratio through the cam drive part (21) on the first transmission gear (2), and the other controls the needle pitch through the eccentric transmission feature (31) on the second transmission gear (3); the cam drive part (21) is provided with multiple different equal radius arc surface segments (211), and the second gear drive part (32) of the second transmission gear (3) meshes with the first gear drive part (22) of the first transmission gear (2) in a way that increases the transmission ratio; When adjusting the stitch length, the cam drive unit (21) operates on the same equal radius arc surface segment (211); when adjusting the differential ratio, the cam drive unit (21) switches to another equal radius arc surface segment (211), and during this process, the rotation angle of the second transmission gear (3) and the rotation angle of the first transmission gear (2) always maintain a predetermined proportional relationship, so that after the equal radius arc surface segment (211) on the cam drive unit (21) is switched, the net adjustment amount of the eccentric transmission feature (31) to the stitch length is zero.

2. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 1, characterized in that, Each time the switch is made to the next equal radius arc segment (211), the first transmission gear (2) rotates at the same angle.

3. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 2, characterized in that, For every fixed angle that the first transmission gear (2) rotates to switch the equal radius arc segment (211), the second transmission gear (3) rotates synchronously by an angle that is an integer multiple of its own rotation of 180 degrees.

4. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 3, characterized in that, The number of equal radius arc segments (211) is at least 6, and the transmission ratio between the first transmission gear (2) and the second transmission gear (3) is no greater than 1:

3.

5. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 1, characterized in that, The radius of the equal radius arc segment (211) changes monotonically along the rotation direction, and adjacent equal radius arc segments (211) are smoothly connected by a transition segment (212).

6. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 1, characterized in that, The cam drive unit (21) is connected to the differential ratio adjustment component (5) via the differential ratio adjustment drive component (4); the eccentric drive feature (31) is connected to the needle pitch adjustment component (7) via the needle pitch adjustment drive component (6).

7. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 6, characterized in that, The differential ratio adjustment transmission assembly (4) includes: The differential ratio adjusting link (41) has one end abutting against the contour of the cam drive unit (21); The rolling element (42) abuts against the other end of the differential ratio adjusting link (41); The oscillating crank (43) is connected at one end to the rolling element (42) and at the other end to the differential ratio adjustment assembly (5).

8. The stepping adjustment fabric feeding mechanism of a sewing machine according to claim 6, characterized in that, The needle pitch adjustment transmission assembly (6) includes: A needle pitch adjusting link (61) is hinged at one end to the eccentric transmission feature (31). Adjust the crank (62), one end of which is hinged to the other end of the stitch pitch adjustment link (61), and the other end is connected to the angle adjustment link (71) of the stitch pitch adjustment assembly (7); The second transmission gear (3) rotates once, driving the angle adjustment link (71) to complete two cycles of oscillation.

9. A sewing machine, characterized in that, It includes the fabric feeding mechanism as described in any one of claims 1-8.

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