Needle distance adjustment mechanism for sewing machine head

Abstract

The present invention provides a needle distance adjustment mechanism for a sewing machine head, belonging to the technical field of sewing machines. It solves the problem that the existing needle distance adjustment mechanism needs to be precisely aligned for adjustment, which makes it difficult to adjust. The needle distance adjustment mechanism for the sewing machine head, the sewing machine includes a machine base, a main shaft, a cloth feeding assembly and a feeding transmission assembly sleeved on the main shaft are arranged in the machine base, the feeding transmission assembly includes a ratchet fixedly connected to the main shaft and an eccentric wheel sleeved on the main shaft, the eccentric wheel is slidably connected with a meshing plate meshed with the ratchet wheel, the cloth feeding assembly is connected to the eccentric wheel by transmission, the needle distance adjustment mechanism includes a driving member and an adjustment frame connected to the driving member, a pressing rod is hinged on the eccentric wheel, an adjustment groove for the end of the pressing rod to be embedded is provided on the outer wall of the eccentric wheel, and the adjustment frame has a ring-shaped adjustment portion. The needle distance adjustment mechanism for the sewing machine head does not need to align one end of the pressing rod with the adjustment groove when adjusting, which improves the convenience of adjustment.

Description

Technical Field

[0001] The invention belongs to the technical field of sewing machines and relates to a needle distance adjustment mechanism of a sewing machine head. Background Art

[0002] When the sewing machine is working, the cloth feeding mechanism mainly lifts and pulls the cloth on the needle plate through the reciprocating elliptical motion of the cloth feeding foot, and continuously drags the cloth to be processed to the machine head through the cooperation of the cloth feeding dog and the cloth feeding foot, and sews it through the needle at the machine head. Many cloths require different distances between the thread loops sewn in different parts, that is, different stitch lengths. Since the action frequency of the machine head remains constant, the stitch length is generally changed by changing the forward and backward movement amplitude of the cloth feeding dog to meet different needs.

[0003] For example, Chinese patent application [Authorization Announcement No.: CN217459837U] discloses a needle distance adjustment device, including a main shaft, on which a main driving source for driving the main shaft to rotate is arranged, and a front and rear driving assembly is connected to the main shaft, and the front and rear driving assembly can rotate eccentrically with the main shaft. The needle distance adjustment mechanism includes a trigger driving source and an adjusting pin drivingly connected to the trigger driving source. When the adjusting pin is inserted into the front and rear driving assembly, the fixed connection relationship between the front and rear driving assembly and the main shaft can be released. When the adjusting pin is pushed out of the front and rear driving assembly, the fixed connection relationship between the front and rear driving assembly and the main shaft can be re-established. The limiting mechanism includes a first limiting part and a second limiting part. The first limiting part and the second limiting part can move relative to each other. When the main shaft rotates to a certain position, the first limiting part The positioning portion can abut against the second limiting portion. At this time, the abutting force between the first limiting portion and the second limiting portion makes it impossible for the main shaft to maintain the original direction of rotation, which means that the adjusting pin has been inserted into the front and rear drive components, and the fixed connection between the front and rear drive components and the main shaft is released. The controller obtains the abutment state between the first limiting portion and the second limiting portion, and uses this as the starting signal for stitch length adjustment, and controls the main driving source to rotate the main shaft in the direction opposite to the original direction until the relative eccentricity between the main shaft axis and the front and rear drive components is the expected value. After obtaining the expected stitch length, the driving source is triggered to drive the adjusting pin to withdraw from the front and rear drive components, and the front and rear drive components are re-fixed with the main shaft. The main shaft drives the front and rear drive components to rotate eccentrically, and controls the cloth feeding component to perform sewing operations with the expected stitch length.

[0004] The above structure requires the controller to control the first limit part to abut against the second limit part. When rotating, the first limit part is turned to the corresponding position, and then inserted into the second limit part to abut against the second limit part, so that the ratchet on the front and rear drive components cannot rotate, and the ratchet and the main shaft are still fixedly connected, so that the main shaft cannot keep rotating in the original direction, triggering the drive source to drive the adjustment pin to insert into the front and rear drive components, and then controlling the drive source to rotate the main shaft in the opposite direction to the original direction, until the relative eccentricity between the main shaft axis and the front and rear drive components is expected, and after completing the adjustment of the needle distance, the adjustment pin is withdrawn from the front and rear drive components. The above makes the first limit part embedded in the second limit part through the controller, and the first limit part needs to be aligned with the second limit part. This plug-in method requires the controller to control it accurately, and the needle distance adjustment is difficult to control. Once a slight deviation occurs, the first limit part cannot be embedded in the second limit part, which increases the difficulty of adjusting the needle distance adjustment device. Summary of the invention

[0005] The purpose of the present invention is to address the above-mentioned problems in the prior art and to propose a needle distance adjustment mechanism for a sewing machine head. The technical problem to be solved by the present invention is: how to solve the problem that the existing needle distance adjustment mechanism requires precise alignment for adjustment, which makes it difficult to adjust.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The invention relates to a stitch length adjustment mechanism for a sewing machine head, wherein the sewing machine comprises a machine base, a main shaft, a cloth feeding assembly and a feeding transmission assembly sleeved on the main shaft, wherein the feeding transmission assembly comprises a ratchet wheel fixedly connected to the main shaft and an eccentric wheel sleeved on the main shaft, wherein the eccentric wheel is slidably connected with a meshing plate meshed with the ratchet wheel, and the cloth feeding assembly is transmission-connected with the eccentric wheel, and is characterized in that the stitch length adjustment mechanism comprises a driving member and an adjusting frame connected with the driving member, wherein a pressing rod is hingedly connected to the eccentric wheel, an adjusting groove for embedding an end of the pressing rod is provided on the outer side wall of the eccentric wheel, and the adjusting frame has an annular adjusting portion, wherein the driving member can push the adjusting portion to move axially along the main shaft so that the adjusting portion pushes one end of the pressing rod to swing radially along the main shaft and press into the adjusting groove, and the pressing rod pushes the meshing plate radially so that the meshing plate is disengaged from the ratchet wheel, and the eccentric wheel is connected with a reset member for pushing the pressing rod and the meshing plate to move radially outward along the main shaft.

[0008] Working principle: when the stitch length needs to be adjusted, the driving member drives the adjusting frame to move along the axial direction of the main shaft, and the adjusting part of the adjusting frame pushes one end of the pressing rod to swing along the radial direction of the main shaft, and swings until one end of the pressing rod is pressed into the adjusting groove, and one end of the pressing rod can push the meshing plate along the radial direction of the eccentric wheel when it swings into the adjusting groove, so that the meshing teeth on the meshing plate are disengaged from the ratchet, and the ratchet is fixed to the main shaft, so that other parts of the feeding transmission assembly except the ratchet do not rotate with the main shaft, by driving the main shaft to rotate, the main shaft only drives the ratchet to rotate, and other parts of the feeding transmission assembly except the ratchet remain stationary, so as to achieve the purpose of changing the relative eccentricity value between the main shaft axis and the front and rear drive assemblies, and realize the adjustment of the stitch length. When the adjustment is completed, the adjusting frame is reset, and the pressing rod relies on the reset member to move outward along the radial direction of the main shaft and disengage the adjusting groove, and the meshing plate relies on the reset member to return to the position aligned with the ratchet. The eccentric wheel of the feeding transmission assembly is meshed with each other, and the rotation of the main shaft drives the entire feeding transmission assembly to rotate, and then the eccentric wheel of the feeding transmission assembly is connected with the cloth feeding assembly, so that the feed tooth of the cloth feeding assembly can move forward and backward, and the reciprocating stroke of the feed tooth changes to achieve the purpose of adjusting the stitch length. The above structure adopts changing the relative eccentricity between the eccentric wheel and the main shaft to achieve the purpose of adjusting the stitch length, and it is by directly hinged on the eccentric wheel that the pressing rod rotates synchronously with the eccentric wheel, and one end of the pressing rod moves along the circumference of the main shaft, and the relative position of the pressing rod and the adjusting groove remains unchanged. Through the annular adjusting portion on the adjusting frame, one end of the pressing rod located at any position can be pressed into the adjusting groove to realize the disengagement of the meshing plate and the ratchet wheel, so that during adjustment, there is no need to align one end of the pressing rod with the adjusting groove, but it can be directly pressed in using the annular adjusting portion, thereby improving the convenience of adjustment.

[0009] In the above-mentioned needle length adjustment mechanism of the sewing machine head, the inner side wall of the adjustment part is a limiting wall, one end of the limiting wall close to the eccentric wheel is a large diameter end, and the other end is a small diameter end, the diameter of the limiting wall gradually decreases from the large diameter end to the small diameter end, and an adjusting roller is sleeved on one end of the pressing rod, the limiting wall is abutted against the adjusting roller, and the adjusting roller rotates along the limiting wall.

[0010] The setting of the limiting wall enables the pressing rod to be pushed radially along the eccentric wheel when the pressing rod is pushed, and the pressing rod can be stably embedded in the adjusting groove to avoid displacement deviation in other directions when the pressing rod moves. Through the setting of the limiting roller, the friction between the end of the pressing rod and the adjusting part is reduced during the pushing process. At this time, the main shaft can continue to rotate, and the adjusting part rolls along the inner wall of the adjusting part through the limiting roller, and can stably push the meshing plate to move radially, thereby further improving the convenience and stability of adjustment.

[0011] In the needle length adjustment mechanism of the above-mentioned sewing machine head, a mounting pin is formed by a protrusion on the end face of one end where the eccentric wheel abuts against the ratchet wheel, and the pressing rod is sleeved on the mounting pin. A torsion spring is provided on the mounting pin, and one end of the torsion spring axially limits the end of the pressing rod on the mounting pin, and the other end hooks the pressing rod and radially limits the pressing rod.

[0012] The function of the torsion spring is, on the one hand, to limit the pressure rod through the torsion spring after it resets itself, so as to avoid collision with the adjustment part, making the reset of the adjustment part more convenient and quick; on the other hand, it can fix the end of the pressure rod axially on the mounting pin, play a positioning role, and improve the compactness of the structure.

[0013] In the above-mentioned needle distance adjustment mechanism of the sewing machine head, the adjustment part is arranged coaxially with the main shaft.

[0014] The arrangement of this structure ensures that when the adjusting part moves along the axial direction, any position has the same effect on the pressing rod, thereby ensuring stable pushing and limiting of the pressing rod by the adjusting part.

[0015] In the above-mentioned needle distance adjustment mechanism of the sewing machine head, one end of the torsion spring is hooked on the middle part of the pressing rod, and the other end of the pressing rod is located outside the adjustment groove and outside the outer side wall of the eccentric wheel.

[0016] The arrangement of this structure enables the torsion spring to stably realize the resetting of the pressing rod, and when the pressing rod moves out of the adjustment slot, the end portion is located on the outer side wall of the eccentric wheel. The arrangement of the pressing rod does not affect the rotation of the eccentric wheel, thereby improving the stability of the rotation.

[0017] In the above-mentioned needle length adjustment mechanism of the sewing machine head, the eccentric wheel is provided with a sliding groove in the radial direction, the bottom wall of the sliding groove is radially recessed to form the above-mentioned adjustment groove, the engaging plate is slidably connected in the sliding groove, and the adjustment roller is connected to a limiting head, the adjustment roller can be arranged in the sliding groove and the limiting head is located in the adjustment groove.

[0018] When the limit head moves to the adjustment groove, the adjustment roller can push the meshing plate to move, thereby separating the meshing plate from the ratchet, so that the adjustment roller has the effect of reducing friction. The adjustment roller is larger in size and has a stronger driving force, which can also achieve a better driving effect.

[0019] In the above-mentioned needle distance adjustment mechanism of the sewing machine head, the driving part is an electromagnet, and the adjustment frame has an adjustment plate arranged axially opposite to the electromagnet, and the adjustment part is located on one side of the adjustment plate. The electromagnet has a push rod, and the end of the push rod is fixedly connected to the adjustment plate by a fastener, so a guide rod is fixedly connected to the adjustment plate, and a guide groove is provided on the electromagnet, one end of the guide rod is inserted into the guide groove, and the adjustment plate can drive the end of the guide rod to slide along the guide groove.

[0020] The sewing machine is provided with a controller which can control the on and off of the electromagnet. When the adjusting plate needs to be pushed to move, the electromagnet is connected, and the push rod of the electromagnet moves axially and drives the adjusting plate to move axially. At this time, the guide rod moves axially synchronously with the adjusting plate, and the end of the guide rod slides along the guide groove, thereby guiding the movement of the adjusting plate. Through the cooperation of the push rod and the guide rod, radial deviation is avoided during the axial movement of the adjusting plate, thereby improving the stability of the movement of the adjusting frame.

[0021] In the stitch length adjustment mechanism of the above-mentioned sewing machine head, a positioning pin is provided above one end of the eccentric wheel close to the ratchet wheel, and the reset member is a reset spring, which is sleeved on the positioning pin. One end of the reset spring is connected to the eccentric wheel, and the other end is connected to the meshing plate. The reset spring has a tendency to push the meshing plate to move toward the pressing rod.

[0022] Through the setting of the reset spring, when resetting, the meshing plate can be pushed to reset, and the meshing plate pushes the pressing rod to move out of the adjustment groove, thereby realizing the rapid reset of the meshing plate and the pressing rod and improving the reset efficiency of the eccentric wheel and the ratchet wheel.

[0023] In the above-mentioned needle distance adjustment mechanism of the sewing machine head, the return spring and the torsion spring are respectively located on both sides of the eccentric wheel.

[0024] The arrangement of this structure makes the forces on both sides of the eccentric wheel more uniform, and the pressing rod is located at one end of the meshing plate, and the return spring is located at the other end of the meshing plate, and the arrangement is more uniform.

[0025] In the above-mentioned needle distance adjustment mechanism of the sewing machine head, the adjustment frame includes an upper mounting plate and a lower mounting plate, the upper mounting plate and the lower mounting plate are spliced, one side of the upper mounting plate and one side of the lower mounting plate are spliced ​​to form the above-mentioned adjustment plate, the other side of the upper mounting plate is a minor arc bar, and the other side of the lower mounting plate is a major arc bar, the upper end of the minor arc bar and the upper end of the major arc bar are connected by fasteners and enclosed to form the above-mentioned adjustment part.

[0026] By adopting the setting of the upper mounting plate and the lower mounting plate, the installation of the adjusting frame is more convenient, and the arc length of the superior arc bar is greater than the arc length of the semicircle, and the arc length of the inferior arc bar is less than the arc length of the semicircle, which makes the installation more stable, improves the supporting strength of the upper part of the adjusting frame, and improves the pushing stability.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. By directly hinged the pressure rod on the eccentric wheel, the pressure rod rotates synchronously with the eccentric wheel, one end of the pressure rod moves along the circumference of the main shaft, and the relative position of the pressure rod and the adjustment groove remains unchanged. Through the annular adjustment part on the adjustment frame, one end of the pressure rod located at any position can be pressed into the adjustment groove to achieve the disengagement of the engaging plate and the ratchet wheel, so that during adjustment, it is not necessary to align one end of the pressure rod with the adjustment groove, but it can be directly pressed into the adjustment groove using the annular adjustment part, thereby improving the convenience of adjustment.

[0029] 2. The setting of the limiting wall enables the pressing rod to be pushed radially along the eccentric wheel when the pressing rod is pushed, and the pressing rod can be stably embedded in the adjustment groove to avoid displacement deviation of the pressing rod in other directions when moving, further improving the convenience and stability of adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the present invention after assembly.

[0031] Figure 2 It is a schematic diagram of the structure of the present invention after being assembled but not installed on the base.

[0032] Figure 3 It is one of the partial structural schematic diagrams of the present invention after assembly.

[0033] Figure 4 This is the second schematic diagram of the partial structure of the present invention after assembly.

[0034] Figure 5 It is a side view of the present invention after being assembled with the feeding rotating assembly.

[0035] Figure 6 yes Figure 5 Sectional view of AA.

[0036] Figure 7 It is a partial exploded view of the present invention after assembly.

[0037] Figure 8 It is a structural schematic diagram of the eccentric wheel of the present invention, in which a pressing rod and a return spring are assembled.

[0038] Fig. 9 It is a side view of the adjustment frame and the electromagnet after being assembled in the present invention.

[0039] Fig.10 yes Fig. 9 Cross-sectional view of BB.

[0040] In the figure, 1, machine base; 11, main shaft; 12, cloth feeding assembly; 2, feeding transmission assembly; 21, ratchet; 22, eccentric wheel; 22a, adjusting groove; 22b, mounting pin; 22c, sliding through groove; 22d, positioning pin; 23, connecting rod; 24, torsion spring; 25, reset member; 3, engaging plate; 4, driving member; 41, push rod; 42, guide groove; 5, adjusting frame; 51, adjusting part; 51a, limiting wall; 52, adjusting plate; 53, guide rod; 54, upper mounting plate; 54a, inferior arc strip; 55, lower mounting plate; 55a, superior arc strip; 6, pressing rod; 61, adjusting roller; 62, limiting head; 7, fastener. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0042] like Figure 1-3 As shown, the stitch length adjustment mechanism of the sewing machine head, the sewing machine includes a machine base 1, a main shaft 11, a cloth feeding assembly 12 and a feeding transmission assembly 2 sleeved on the main shaft 11 are arranged in the machine base 1, the feeding transmission assembly 2 includes a ratchet 21 fixedly connected to the main shaft 11, an eccentric wheel 22 sleeved on the main shaft 11 and a connecting rod 23 sleeved on the eccentric wheel 22, the connecting rod 23 is connected with the eccentric wheel 22 with a flat key, the eccentric wheel 22 is slidably connected with an engaging plate 3 meshing with the ratchet wheel 21, and the cloth feeding assembly 12 is drivingly connected with the connecting rod 23.

[0043] Specifically, Figure 1-10 As shown, the stitch length adjustment mechanism includes a driving member 4 and an adjustment frame 5 connected to the driving member 4, a pressing rod 6 is hinged on the eccentric wheel 22, and an adjustment groove 22a for the end of the pressing rod 6 to be embedded is provided on the outer wall of the eccentric wheel 22, and the adjustment frame 5 has a ring-shaped adjustment portion 51, the driving member 4 can push the adjustment portion 51 to move axially along the main shaft 11 so that the adjustment portion 51 pushes one end of the pressing rod 6 to swing radially along the main shaft 11 and press into the adjustment groove 22a, and the pressing rod 6 pushes the meshing plate 3 radially to disengage the meshing plate 3 from the ratchet 21, and the eccentric wheel 22 is connected with a reset member 25 for pushing the pressing rod 6 and the meshing plate 3 to move radially outward along the main shaft 11.

[0044] Working principle: when the stitch length needs to be adjusted, the driving member 4 drives the adjusting frame 5 to move axially along the main shaft 11, and the driving member pushes the adjusting portion 51 to move axially along the main shaft 11 so that the adjusting portion 51 pushes one end of the pressing rod 6 to swing radially along the main shaft 11, and swings until one end of the pressing rod 6 is pressed into the adjusting groove 22a, and when the one end of the pressing rod 6 swings into the adjusting groove 22a, it can push the meshing plate 3 in the radial direction of the eccentric wheel 22, so that the meshing teeth on the meshing plate 3 are disengaged from the ratchet 21, and the ratchet 21 is fixedly connected to the main shaft 11, so that the other parts of the feeding transmission assembly 2 except the ratchet 21 do not rotate with the main shaft 11, and by driving the main shaft 11 to rotate, the main shaft 11 only drives the ratchet 21 to rotate, and the other parts of the feeding transmission assembly 2 except the ratchet 21 do not move. The purpose of changing the relative eccentricity between the axis of the main shaft 11 and the front and rear drive components is achieved, and the stitch length is adjusted. After the adjustment is completed, the adjustment frame 5 is reset, and the pressing rod 6 relies on the reset member 25 to move radially outward along the main shaft 11 and move out of the adjustment groove 22a, and the meshing plate 3 relies on the reset member 25 to restore to mesh with the ratchet 21. At this time, the rotation of the main shaft 11 drives the entire feeding transmission assembly 2 to rotate, and then the eccentric wheel 22 of the feeding transmission assembly 2 is connected to the cloth feeding assembly 12, so that the feed tooth of the cloth feeding assembly 12 can move forward and backward, and the reciprocating stroke of the feed tooth is changed to achieve the purpose of adjusting the stitch length. The above structure adopts the method of changing the relative eccentricity between the eccentric wheel 22 and the main shaft 11 The relative eccentricity value is set to achieve the purpose of adjusting the stitch length, and the pressing rod 6 is directly hinged on the eccentric wheel 22. The pressing rod 6 rotates synchronously with the eccentric wheel 22, and one end of the pressing rod 6 moves circumferentially along the main shaft 11. The relative position of the pressing rod 6 and the adjusting groove 22a remains unchanged. Through the annular adjusting portion 51 on the adjusting frame 5, one end of the pressing rod 6 located at any position can be pressed into the adjusting groove 22a to achieve the disengagement of the engaging plate 3 and the ratchet 21, so that during adjustment, it is not necessary to align one end of the pressing rod 6 with the adjusting groove 22a, but it can be directly pressed in using the annular adjusting portion 51, thereby improving the convenience of adjustment.

[0045] like Figure 2-6 As shown, the inner wall of the adjusting portion 51 is a limiting wall 51a, and one end of the limiting wall 51a close to the eccentric wheel 22 is a large diameter end, and the other end is a small diameter end. The diameter of the limiting wall 51a gradually decreases from the large diameter end to the small diameter end. An adjusting roller 61 is sleeved on one end of the pressing rod 6, and the limiting wall 51a abuts against the adjusting roller 61, and the adjusting roller 61 rotates along the limiting wall 51a. A mounting pin 22b is formed by a protrusion on the end surface of the end where the eccentric wheel 22 abuts against the ratchet wheel 21. The pressing rod 6 is sleeved on the mounting pin 22b, and a torsion spring 24 is provided on the mounting pin 22b. One end of the torsion spring 24 axially limits the end of the pressing rod 6 on the mounting pin 22b, and the other end hooks the pressing rod 6 and radially limits the pressing rod 6. The adjusting portion 51 is coaxially arranged with the main shaft 11.

[0046] like Figure 4-8As shown, one end of the torsion spring 24 presses one end of the pressing rod 6 onto the eccentric wheel 22, and the other end of the torsion spring 24 is hooked in the middle of the pressing rod 6. The other end of the pressing rod 6 is located outside the adjusting groove 22a and outside the outer wall of the eccentric wheel 22. The eccentric wheel 22 is radially provided with a sliding groove 22c, and the bottom wall of the sliding groove 22c is radially recessed to form the above-mentioned adjusting groove 22a. The engaging plate 3 is slidingly connected in the sliding groove 22c, and one end of the pressing rod 6 is axially rotatably connected to the limiting roller and the limiting head 62. The limiting roller can be set in the sliding groove 22c and the limiting head 62 is located in the adjusting groove 22a.

[0047] like Figure 3 , Figure 4 , Fig. 9 and Fig.10 As shown, the driving member 4 is an electromagnet, and the adjusting frame 5 has an adjusting plate 52 which is axially opposite to the electromagnet. The adjusting portion 51 is located on one side of the adjusting plate 52. The electromagnet has a push rod 41, and the end of the push rod 41 is fixedly connected to the adjusting plate 52 by a fastener 7. A guide rod 53 is fixedly connected to the adjusting plate 52. A guide groove 42 is provided on the electromagnet, and one end of the guide rod 53 is inserted into the guide groove 42, and the adjusting plate 52 can drive the end of the guide rod 53 to slide along the guide groove 42. A positioning pin 22d is provided on the eccentric wheel 22, and the reset member 25 is a reset spring, which is sleeved on the positioning pin 22d. One end of the reset spring is connected to the eccentric wheel 22, and the other end is connected to the meshing plate 3. The reset spring has a tendency to push the meshing plate 3 to move toward the pressing rod 6. The reset spring and the torsion spring 24 are respectively located on both sides of the eccentric wheel 22.

[0048] like Figure 3 and Figure 4 As shown, the adjustment frame 5 includes an upper mounting plate 54 and a lower mounting plate 55, and the upper mounting plate 54 and the lower mounting plate 55 are spliced, and one side of the upper mounting plate 54 and one side of the lower mounting plate 55 are spliced ​​to form the above-mentioned adjustment plate 52, and the other side of the upper mounting plate 54 has an inferior arc bar 54a, and the other side of the lower mounting plate 55 has a superior arc bar 55a, and the upper end of the inferior arc bar 54a and the upper end of the superior arc bar 55a are connected by fasteners 7 and enclosed to form the above-mentioned adjustment part 51.

[0049] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A stitch length adjustment mechanism for a sewing machine head, the sewing machine comprising a machine base (1), wherein a main shaft (11), a cloth feeding assembly (12) and a feeding transmission assembly (2) sleeved on the main shaft (11) are arranged in the machine base (1), wherein the feeding transmission assembly (2) comprises a ratchet (21) fixedly connected to the main shaft (11) and an eccentric wheel (22) sleeved on the main shaft (11), wherein a meshing plate (3) meshing with the ratchet wheel (21) is slidably connected to the eccentric wheel (22), and the cloth feeding assembly (12) is drivingly connected to the eccentric wheel (22), characterized in that: The needle distance adjustment mechanism comprises a driving member (4) and an adjustment frame (5) connected to the driving member (4); a pressing rod (6) is hingedly connected to the eccentric wheel (22); an adjustment groove (22a) is provided on the outer wall of the eccentric wheel (22) for the end of the pressing rod (6) to be inserted; the adjustment frame (5) has an annular adjustment portion (51); the driving member (4) can push the adjustment portion (51) to move axially along the main shaft (11) so that the adjustment portion (51) pushes one end of the pressing rod (6) to swing radially along the main shaft (11) and press into the adjustment groove (22a); and the pressing rod (6) pushes the meshing plate (3) radially so that the meshing plate (3) is disengaged from the ratchet wheel (21); and a reset member (25) is connected to the eccentric wheel (22) for pushing the pressing rod (6) and the meshing plate (3) to move radially outward along the main shaft (11).

2. The needle distance adjustment mechanism of the sewing machine head according to claim 1, characterized in that: The inner side wall of the adjusting portion (51) is a limiting wall (51a); one end of the limiting wall (51a) close to the eccentric wheel (22) is a large diameter end, and the other end is a small diameter end; the diameter of the limiting wall (51a) gradually decreases from the large diameter end to the small diameter end; an adjusting roller (61) is sleeved on one end of the pressing rod (6); the limiting wall (51a) abuts against the adjusting roller (61), and the adjusting roller (61) rotates along the limiting wall (51a).

3. The needle distance adjustment mechanism of the sewing machine head according to claim 1 or 2, characterized in that: A mounting pin (22b) is formed on the end surface of the eccentric wheel (22) abutting against the ratchet wheel (21). The pressing rod (6) is sleeved on the mounting pin (22b). A torsion spring (24) is provided on the mounting pin (22b). One end of the torsion spring (24) axially limits the end of the pressing rod (6) on the mounting pin (22b), and the other end hooks the pressing rod (6) and limits the pressing rod (6) radially.

4. The needle distance adjustment mechanism of the sewing machine head according to claim 1 or 2, characterized in that: The adjusting portion (51) is coaxially arranged with the main shaft (11).

5. The needle distance adjustment mechanism of the sewing machine head according to claim 3, characterized in that: One end of the torsion spring (24) is hooked on the middle part of the pressing rod (6), and the other end of the pressing rod (6) is located outside the adjustment groove (22a) and outside the outer side wall of the eccentric wheel (22).

6. The needle distance adjustment mechanism of the sewing machine head according to claim 2, characterized in that: The eccentric wheel (22) is provided with a sliding groove (22c) in the radial direction, and the bottom wall of the sliding groove (22c) is recessed in the radial direction to form the above-mentioned adjustment groove (22a). The meshing plate (3) is slidably connected in the sliding groove (22c). The adjustment roller (61) is connected to a limit head (62). The adjustment roller (61) can be arranged in the sliding groove (22c) and the limit head (62) is located in the adjustment groove (22a).

7. The needle distance adjustment mechanism of the sewing machine head according to claim 1 or 2, characterized in that: The driving member (4) is an electromagnet. The adjusting frame (5) has an adjusting plate (52) arranged axially opposite to the electromagnet. The adjusting portion (51) is located on one side of the adjusting plate (52). The electromagnet has a push rod (41). The end of the push rod (41) is fixedly connected to the adjusting plate (52) by a fastener (7). Therefore, a guide rod (53) is fixedly connected to the adjusting plate (52). The electromagnet is provided with a guide groove (42). One end of the guide rod (53) is inserted into the guide groove (42). The adjusting plate (52) can drive the end of the guide rod (53) to slide along the guide groove (42).

8. The needle distance adjustment mechanism of the sewing machine head according to claim 3, characterized in that: The eccentric wheel (22) is provided with a positioning pin (22d), and the reset member (25) is a reset spring, which is sleeved on the positioning pin (22d). One end of the reset spring is connected to the eccentric wheel (22), and the other end is connected to the meshing plate (3). The reset spring has a tendency to push the meshing plate (3) to move toward the pressing rod (6).

9. The needle distance adjustment mechanism of the sewing machine head according to claim 8, characterized in that: The return spring and the torsion spring (24) are respectively located on two sides of the eccentric wheel (22).

10. The needle distance adjustment mechanism of the sewing machine head according to claim 7, characterized in that: The adjustment frame (5) comprises an upper mounting plate (54) and a lower mounting plate (55); the upper mounting plate (54) and the lower mounting plate (55) are spliced; one side of the upper mounting plate (54) and one side of the lower mounting plate (55) are spliced ​​to form the above-mentioned adjustment plate (52); the other side of the upper mounting plate (54) is a minor arc bar (54a); the other side of the lower mounting plate (55) is a major arc bar (55a); the upper end of the minor arc bar (54a) and the upper end of the major arc bar (55a) are connected by a fastener (7) and enclosed to form the above-mentioned adjustment portion (51).

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