Motor control method of sewing machine and sewing machine

Abstract

The invention relates to the technical field of sewing machines, in particular to a motor control method of a sewing machine and the sewing machine using the method for sewing. The method mainly comprises the steps that in a stitch length sewing period, a stitch length motor is controlled to rotate in a track point A-A'interval and a track point B-B 'interval, the angle of a swing plate base is changed, and therefore the motion track shape of a feeding tooth is changed; one of the track point A and the track point A'and one of the track point B and the track point B 'serve as intervention points of rotation of the stitch length motor, and the other one of the track point A and the track point A' and the other one of the track point B and the track point B 'serve as end points of rotation of the stitch length motor; and the positions of an intervention point and an end point of rotation of the stitch length motor are controlled, so that the stitch length motor can rotate in an angle range in which the stitch length can be effectively adjusted. Segmented control is adopted, and various feeding track changes and track fine adjustment can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewing machines, and in particular to a motor control method for a sewing machine and a sewing machine that uses the motor control method for sewing. Background Art

[0002] In the prior art, a sewing machine usually drives the main shaft to rotate through a main shaft driving member, and the main shaft drives the feeding eccentric wheel and the lifting eccentric wheel to realize feeding, and a motor is added to control the angle of the swing plate seat to realize the change of stitch length. The feeding mechanism of this sewing machine often drives the main shaft through a single main shaft driving member to drive the translation and lifting of the feed dog at the same time. The timing and speed of the two movements are relatively fixed and cannot be adjusted, and the trajectory of the feed dog is also relatively uniform. Summary of the invention

[0003] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a motor control method for a sewing machine, which can realize a variety of feeding trajectory changes and trajectory fine-tuning.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a motor control method for a sewing machine, the sewing machine comprising: a feeding mechanism connected between a main shaft and a tooth frame, a feeding tooth being installed on the tooth frame, the feeding mechanism having a swing plate seat capable of rotating to change an angle, the angle of the swing plate seat determining the stitch length of the sewing machine; a stitch length motor connected to the swing plate seat via the needle length adjusting mechanism and driving the swing plate seat to rotate; a main motor driving the main shaft to rotate and driving the tooth frame and the feeding tooth to move via the feeding mechanism; within a stitch length sewing cycle, when the angle of the swing plate seat remains unchanged, the motion trajectory of the feeding tooth is an elliptical trajectory line, the elliptical trajectory line passing through a trajectory point Z at the highest position above a needle plate, a trajectory point O at the height of the needle plate, a trajectory point Z′ at the lowest position below the needle plate and a trajectory point O′ at the height of the needle plate; the motor control method for the sewing machine is: on the elliptical trajectory line On the top, take the track point A located in the track point ZO interval, the track point A′ located in the track point OZ′ interval, the track point B located in the track point Z′-O′ interval and the track point B′ located in the track point O′-Z interval; in one stitch length sewing cycle, control the rotation of the stitch length motor in the track point AA′ interval and the track point BB′ interval to change the angle of the swing plate seat, thereby changing the shape of the motion trajectory of the feed dog; one of the track points A and A′, one of the track points B and B′ are used as the intervention point of the rotation of the stitch length motor, and the other of the track points A and A′, and the other of the track points B and B′ are used as the end point of the rotation of the stitch length motor; control the positions of the intervention point and the end point of the rotation of the stitch length motor, so that the stitch length motor rotates within the angle range that can effectively adjust the stitch length.

[0006] Preferably, the needle distance motor is controlled not to rotate in the interval between track points A′-B and track points B′-A, so that the angle of the swing plate seat remains unchanged.

[0007] Preferably, the needle distance motor is controlled to have a maximum / minimum rotation angle in the interval between track points A′-B and track points B′-A.

[0008] Preferably, the rotation angle of the needle pitch motor in the interval between track points A′ and B and the rotation angle of the needle pitch motor in the interval between track points B′ and A are controlled separately.

[0009] The present invention also provides a sewing machine, which performs sewing using the motor control method of the sewing machine as described above.

[0010] Compared with the prior art, the present invention has significant improvements:

[0011] The motor control method of the sewing machine of the present invention operates the stitch motor to adjust the angle of the swing plate seat in a stitch sewing cycle to change the stitch length. The change in the angle of the swing plate seat will cause the feed dog to be displaced accordingly. The displacement is superimposed on the displacement of the feed dog generated by the main motor, which can change the motion trajectory of the feed dog and achieve the adjustment of the motion trajectory of the feed dog during sewing. At the same time, the motor control method of the sewing machine of the present invention adopts segmented control, and controls the position of the intervention point for adjusting the stitch motor angle change and the position of the end point for adjusting the stitch motor angle change to ensure that the stitch motor rotates only within the angle range that can effectively adjust the stitch length, so that the feed dog motion trajectory change and trajectory fine-tuning can be smoothly achieved, and the stitch length adjustable stroke will not be exceeded, and other functional actions such as lifting the presser foot and cutting the thread will not be interfered with. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the structure of a sewing machine according to an embodiment of the present invention.

[0013] Figure 2 Schematic diagram of the motion trajectory of the feed dog when the angle of the swing plate seat remains unchanged in an embodiment of the present invention.

[0014] Figure 3 This is a schematic diagram of the rotation angle of the stitch motor in the first implementation of the motor control method for a sewing machine according to an embodiment of the present invention.

[0015] Figure 4 It is a schematic diagram of the motion trajectory of the feed dog in the first implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0016] Figure 5 This is a schematic diagram of the rotation angle of the stitch motor in the second implementation of the motor control method for a sewing machine according to an embodiment of the present invention.

[0017] Figure 6 It is a schematic diagram of the motion trajectory of the feed dog in the second implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0018] Figure 7 This is a schematic diagram of the rotation angle of the stitch motor in the third implementation of the motor control method for a sewing machine according to an embodiment of the present invention.

[0019] Figure 8 It is a schematic diagram of the motion trajectory of the feed dog in the third implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0020] Fig. 9 This is a schematic diagram of the rotation angle of the stitch motor in the fourth implementation of the motor control method for a sewing machine according to an embodiment of the present invention.

[0021] Fig.10 It is a schematic diagram of the motion trajectory of the feed dog in the fourth implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0022] Fig.11 This is a schematic diagram of the rotation angle of the stitch motor in the fifth implementation of the motor control method for a sewing machine according to an embodiment of the present invention.

[0023] Fig.12 It is a schematic diagram of the motion trajectory of the feed dog in the fifth implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0024] Fig.13 This is a schematic diagram of the rotation angle of the stitch motor in the sixth implementation of the motor control method for a sewing machine according to an embodiment of the present invention.

[0025] Fig.14 It is a schematic diagram of the motion trajectory of the feed dog in the sixth implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0026] Fig.15 This is a schematic diagram of the rotation angle of the stitch motor in the seventh implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0027] Fig.16 It is a schematic diagram of the motion trajectory of the feed dog in the seventh implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0028] Fig.17 This is a schematic diagram of the rotation angle of the stitch motor in the eighth implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0029] Fig.18It is a schematic diagram of the motion trajectory of the feed dog in the eighth implementation manner of the motor control method for a sewing machine according to an embodiment of the present invention.

[0030] The reference numerals are described as follows:

[0031] 1 Needle distance motor

[0032] 2 Main motor

[0033] 3 Spindle

[0034] 4 tooth bracket

[0035] 5 feed dog

[0036] 6 Swing plate seat

[0037] 7 Feed shaft

[0038] 8 Feeding eccentric wheel

[0039] 9 Feed connecting rod

[0040] 10 Short swing board

[0041] 11 Long swing board

[0042] 12 Feed crank

[0043] 13 Tooth lifting axis

[0044] 14 Tooth lifting connecting rod

[0045] 15 Tooth lifting crank

[0046] 16 tooth lift fork crank

[0047] 17 Stitch cam

[0048] 18 Stitch adjustment crank

[0049] 19 Needle length adjustment lever

[0050] 20 Needle plate

[0051] 21 Presser foot lifting cam

[0052] 22 Presser foot crank

[0053] 23 Presser foot lifter

[0054] 24 Presser foot rear lever DETAILED DESCRIPTION

[0055] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0056] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0059] like Figures 1 to 18 As shown, an embodiment of the motor control method of a sewing machine of the present invention.

[0060] See also Figure 1 The structure of the sewing machine in this embodiment is an existing structure, which includes a feeding mechanism, a stitch length motor 1 and a main motor 2. The feeding mechanism is connected between the main shaft 3 and the tooth frame 4, and a feeding tooth 5 is installed on the tooth frame 4. The feeding mechanism has a swing plate seat 6 that can rotate to change the angle. The swing plate seat 6 rotates around a fixed swing fulcrum, and the angle of the swing plate seat 6 determines the stitch length of the sewing machine. The stitch length motor 1 is connected to the swing plate seat 6 through the stitch length adjustment mechanism, and drives the swing plate seat 6 to rotate, so that the angle of the swing plate seat 6 changes, thereby adjusting the stitch length. The main motor 2 drives the main shaft 3 to rotate, and drives the tooth frame 4 and the feeding tooth 5 to move through the feeding mechanism.

[0061] Specifically, the feeding mechanism includes a feeding unit connected between the main shaft 3 and the front end of the tooth frame 4 and a tooth lifting unit connected between the main shaft 3 and the rear end of the tooth frame 4. The feeding unit includes a feeding shaft 7 arranged parallel to the main shaft 3, a feeding eccentric wheel 8 fixed on the main shaft 3, a feeding connecting rod 9, a short swing plate 10, a long swing plate 11, and a feeding crank 12 fixed on one end of the feeding shaft 7, and the other end of the feeding shaft 7 is connected to the front end of the tooth frame 4. The upper end of the feeding connecting rod 9 can be rotatably sleeved on the outer circumference of the feeding eccentric wheel 8, the lower end of the feeding connecting rod 9, one end of the short swing plate 10 and one end of the long swing plate 11 are coaxially hinged by a pin arranged parallel to the main shaft 3, the other end of the short swing plate 10 is hinged to the swing plate seat 6 by a pin arranged parallel to the main shaft 3, and the other end of the long swing plate 11 is hinged to the feeding crank 12 by a pin arranged parallel to the main shaft 3. The tooth lifting unit includes a tooth lifting shaft 13 arranged parallel to the main shaft 3, a tooth lifting eccentric wheel fixed on the main shaft 3, a tooth lifting connecting rod 14, and a tooth lifting crank 15 and a tooth lifting fork crank 16 fixed at both ends of the tooth lifting shaft 13. The upper end of the tooth lifting connecting rod 14 can be rotatably mounted on the outer peripheral surface of the tooth lifting eccentric wheel. The lower end of the tooth lifting connecting rod 14 is hinged with the tooth lifting crank 15 through a pin arranged parallel to the main shaft 3. The tooth lifting fork crank 16 is connected to the rear end of the tooth frame 4. The tooth frame 4 and the feed tooth 5 are located below the needle plate 20. The main shaft 3 drives the tooth frame 4 and the feed tooth 5 to move back and forth through the feeding unit, and drives the tooth frame 4 and the feed tooth 5 to move up and down through the tooth lifting unit. Therefore, the feed tooth 5 performs a composite motion of moving back and forth and moving up and down. When the angle of the swing plate seat 6 remains unchanged, the motion trajectory of the feed tooth 5 is roughly elliptical.

[0062] The stitch adjustment mechanism includes a stitch cam 17 fixed on the output shaft of the stitch motor 1, a stitch adjustment crank 18 and a stitch adjustment connecting rod 19. The stitch adjustment crank 18 can rotate around a fixed fulcrum. One end of the stitch adjustment crank 18 is rotatably mounted with a stitch adjustment ball that contacts and cooperates with the working contour surface of the stitch cam 17. The two ends of the stitch adjustment connecting rod 19 are respectively hinged with the other end of the stitch adjustment crank 18 and the swing plate seat 6. The working contour surface of the stitch cam 17 has a stitch adjustment driving section. When the stitch cam 17 is driven by the stitch motor 1 to rotate until the stitch adjustment driving section acts on the stitch adjustment ball, the stitch adjustment crank 18 can be driven to rotate, and the swing plate seat 6 is driven to rotate through the stitch adjustment connecting rod 19, so that the angle of the swing plate seat 6 changes, and the stitch adjustment is achieved. Accordingly, within one rotation angle of the stitch motor 1, there is an angle range (i.e., stitch adjustment area) in which the stitch adjustment drive section of the stitch cam 17 contacts the stitch adjustment ball so as to effectively adjust the stitch length. It is a prior art that the angle of the swing plate seat 6 determines the stitch length of the sewing machine, which is understandable to those skilled in the art and will not be described in detail herein. In conventional sewing methods, the rotation angle of the stitch motor 1 is controlled to be maintained at a certain value within the angle range that can effectively adjust the stitch length, so that the angle of the swing plate seat 6 remains unchanged, and sewing is performed with a fixed stitch length.

[0063] In addition, the stitch motor 1 can also drive other functional mechanisms at the same time to realize other functions, such as presser foot lifting function and thread trimming function. Taking the presser foot lifting function as an example, the output shaft of the stitch motor 1 is also provided with a presser foot lifting cam 21, one end of the presser foot lifting crank 22 is rotatably mounted with a presser foot lifting ball that contacts and cooperates with the working contour surface of the presser foot lifting cam 21, and the two ends of the presser foot lifting push rod 23 are respectively hinged with the other end of the presser foot lifting crank 22 and one end of the presser foot lifting rear lever 24, and the other end of the presser foot lifting rear lever 24 is connected to the presser foot lifting assembly. The working contour surface of the presser foot lifting cam 21 has a presser foot lifting driving section. When the presser foot lifting cam 21 is driven by the stitch motor 1 and rotates until the presser foot lifting driving section acts on the presser foot lifting ball, the presser foot lifting crank 22 can be driven to rotate, and the presser foot lifting assembly is driven to move through the presser foot lifting push rod 23 and the presser foot lifting rear lever 24 to realize presser foot lifting. Correspondingly, within one rotation angle of the stitch length motor 1, there is also an angle range (i.e., presser foot lifting area) that allows the presser foot lifting driving section of the presser foot lifting cam 21 to contact the presser foot lifting ball so as to effectively lift the presser foot. The angle range (presser foot lifting area) in which the stitch length motor 1 can effectively lift the presser foot does not interfere with the angle range (stitch length adjustment area) in which the stitch length motor 1 can effectively adjust the stitch length. The working contour surface of the stitch length cam 17 also has an avoidance section that prevents the stitch length adjustment mechanism from operating. The working contour surface of the presser foot lifting cam 21 also has an avoidance section that prevents the presser foot lifting assembly from operating, so as to achieve the non-interference between the stitch length adjustment action and the presser foot lifting action driven by the same stitch length motor 1, thus forming a one-to-two structure. Based on this principle, on this basis, a thread trimming function can also be added to form a one-to-three structure.

[0064] In a stitch length sewing cycle, when the angle of the swing plate seat 6 remains unchanged, the motion trajectory of the feed dog 5 is an elliptical trajectory line, such as Figure 2 As shown, the elliptical trajectory line passes through the trajectory point Z at the highest position above the needle plate 20, the trajectory point O at the height of the needle plate 20, the trajectory point Z′ at the lowest position below the needle plate 20, and the trajectory point O′ at the height of the needle plate 20. Figure 2 The line OO' in the middle represents the needle plate plane. When the sewing machine is sewing forward, the movement direction of the feed dog 5 is 0-Z'-O'-ZO, and the movement direction of the feed dog 5 is opposite to it when the sewing machine is sewing backward.

[0065] The motor control method of the sewing machine of the present embodiment is as follows: on the elliptical trajectory line of the feed dog 5 when the angle of the swing plate seat 6 remains unchanged, take the trajectory point A located in the trajectory point ZO interval, the trajectory point A′ located in the trajectory point OZ′ interval, the trajectory point B located in the trajectory point Z′-O′ interval, and the trajectory point B′ located in the trajectory point O′-Z interval. In one stitch length sewing cycle, the stitch length motor 1 is controlled to rotate in the trajectory point AA′ interval and the trajectory point BB′ interval, so that the angle of the swing plate seat 6 changes, thereby changing the shape of the motion trajectory of the feed dog 5. Among them, one of the trajectory point A and the trajectory point A′, one of the trajectory point B and the trajectory point B′ is used as the intervention point of the rotation of the stitch length motor 1, and the other of the trajectory point A and the trajectory point A′, and the other of the trajectory point B and the trajectory point B′ is used as the end point of the rotation of the stitch length motor 1. The positions of the intervention point and the end point of the rotation of the stitch length motor 1 are controlled so that the stitch length motor 1 rotates within the angle range that can effectively adjust the stitch length.

[0066] The motor control method of the sewing machine of the present embodiment operates the stitch motor 1 to adjust the angle of the swing plate seat 6 in one stitch sewing cycle to change the stitch length. The change in the angle of the swing plate seat 6 will cause the feed dog 5 to be displaced accordingly. The displacement is superimposed on the displacement of the feed dog 5 driven by the main motor 2, so that the motion trajectory of the feed dog 5 can be changed, thereby realizing the adjustment of the motion trajectory of the feed dog 5 during sewing. Since the stitch adjustment driving section of the stitch cam 17 has a limited range for stitch adjustment, and only one section of the angle area in one rotation angle of the stitch motor 1 is used to effectively adjust the stitch length, and the other angle areas are required to perform other functional actions such as lifting the presser foot and cutting the thread, the motion range of the swing plate seat 6 and the feed dog 5 is limited. In other words, the stitch motor 1 can only rotate within the angle range (stitch adjustment area) that can effectively adjust the stitch length to change the angle of the swing plate seat 6 to change the stitch length, thereby changing the shape of the motion trajectory of the feed dog 5. If the rotation angle of the stitch motor 1 exceeds this range, the stitch length will no longer change, or enter the presser foot lifting / thread cutting stroke. Based on this, the motor control method of the sewing machine of this embodiment adopts segmented control, by controlling the position of the intervention point of the angle change of the stitch length motor 1 and the position of the end point of the angle change of the stitch length motor 1, to ensure that the stitch length motor 1 rotates only within the angle range that can effectively adjust the stitch length, thereby smoothly realizing the change of the motion trajectory and fine-tuning of the trajectory of the feed dog 5, and will not exceed the adjustable stroke of the stitch length, and will not interfere with other functional actions such as lifting the presser foot and trimming the thread.

[0067] For ease of description, Figure 2 The left side of the paper is left-hand. Figure 2 The following specific instructions are given on the right side of the paper.

[0068] When the sewing machine is sewing, the movement direction of the feed dog 5 is A-0-A′-Z′-BO′-B′-ZA. There are four sewing control rules for controlling the rotation of the stitch motor 1 in the track point AA′ interval and the track point BB′ interval:

[0069] Positive seam control rule ①: When the feed dog 5 moves to the track point A, the needle pitch motor 1 works and rotates clockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from left to right; after the feed dog 5 reaches the track point O and before reaching the track point A', the needle pitch motor 1 rotates counterclockwise, causing the feed dog 5 to move from right to left. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the AA' segment track line close to a vertical straight line. At this time, ∠AOA' is an obtuse angle, and the feed dog 5 in the track point AO interval is higher than the horizontal position under the conventional sewing method.

[0070] Positive seam control rule ②: When the feed dog 5 moves to the track point B, the needle pitch motor 1 works and rotates clockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from right to left; after the feed dog 5 reaches the track point O' and before reaching the track point B', the needle pitch motor 1 rotates counterclockwise, causing the feed dog 5 to move from left to right. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the BB' segment track line close to a vertical straight line. At this time, ∠BO'B' is an obtuse angle, and the feed dog 5 in the track point B'-O' interval is higher than the horizontal position under the conventional sewing method.

[0071] Positive seam control rule ③: When the feed dog 5 moves to the track point A, the needle pitch motor 1 works and rotates counterclockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from right to left; after the feed dog 5 reaches the track point O and before reaching the track point A', the needle pitch motor 1 rotates clockwise, causing the feed dog 5 to move from left to right. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the AO segment track line and the OA' segment track line closer to the horizontal relative to the original track line. At this time, ∠AOA' is an acute angle, and the feed dog 5 in the track point AO interval is lower than the horizontal position under the conventional sewing method.

[0072] Positive seam control rule ④: When the feed dog 5 moves to the track point B, the needle pitch motor 1 works and rotates counterclockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from left to right; after the feed dog 5 reaches the track point O' and before reaching the track point B', the needle pitch motor 1 rotates clockwise, causing the feed dog 5 to move from right to left. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the BO' segment track line and the O'B' segment track line closer to the horizontal relative to the original track line. At this time, ∠BO'B' is an acute angle, and the feed dog 5 in the track point B'-O' interval is lower than the horizontal position under the conventional sewing method.

[0073] When the sewing machine is reverse stitching, the movement direction of the feed dog 5 is B′-O′-BZ′-A′-OAZB′. There are four reverse stitching control rules for controlling the rotation of the stitch motor 1 in the track point B′-B interval and the track point A′-A interval:

[0074] Reverse stitch control rule ①: When the feed dog 5 moves to the track point B', the needle pitch motor 1 works and rotates counterclockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from right to left; after the feed dog 5 reaches the track point O' and before reaching the track point B, the needle pitch motor 1 rotates clockwise, causing the feed dog 5 to move from left to right. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the B'B segment track line close to a vertical straight line. At this time, ∠B'O'B is an obtuse angle, and the feed dog 5 in the track point B'-O' interval is higher than the horizontal position under the conventional sewing method.

[0075] Reverse stitch control rule ②: When the feed dog 5 moves to the track point A′, the needle pitch motor 1 works and rotates counterclockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from left to right; after the feed dog 5 reaches the track point O and before reaching the track point A, the needle pitch motor 1 rotates clockwise, causing the feed dog 5 to move from right to left. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 and the displacement of the feed dog 5 driven by the main motor 2 are superimposed on each other, which can make the A′A segment track line close to a vertical straight line. At this time, ∠A′OA is an obtuse angle, and the feed dog 5 in the track point AO interval is higher than the horizontal position under the conventional sewing method.

[0076] Reverse stitch control rule ③: When the feed dog 5 moves to the track point B', the needle pitch motor 1 works and rotates clockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from left to right; after the feed dog 5 reaches the track point O' and before reaching the track point B, the needle pitch motor 1 rotates counterclockwise, causing the feed dog 5 to move from right to left. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the B'O' segment track line and the O'B segment track line closer to the horizontal relative to the original track line. At this time, ∠B'O'B is an acute angle, and the feed dog 5 in the track point B'-O' interval is lower than the horizontal position under the conventional sewing method.

[0077] Reverse stitch control rule ④: When the feed dog 5 moves to the track point A′, the needle pitch motor 1 works and rotates clockwise, causing the angle of the swing plate seat 6 to change, which will cause the feed dog 5 to move from right to left; after the feed dog 5 reaches the track point O and before reaching the track point A, the needle pitch motor 1 rotates counterclockwise, causing the feed dog 5 to move from left to right. The displacement of the feed dog 5 caused by the rotation of the needle pitch motor 1 is superimposed on the displacement of the feed dog 5 driven by the main motor 2, which can make the A′O segment track line and the OA segment track line closer to the horizontal relative to the original track line. At this time, ∠A′OA is an acute angle, and the feed dog 5 in the track point AO interval is lower than the horizontal position under the conventional sewing method.

[0078] In the above forward sewing and reverse sewing control rules, the rotation range of the stitch length motor 1 is within the angle range (stitch length adjustment area) that can effectively adjust the stitch length.

[0079] By combining the above four forward sewing control rules during forward sewing, and controlling and adjusting the positions of the intervention point (track point A and track point B) and the end point (track point A′ and track point B′) of the rotation of the stitch length motor 1, and by combining the above four reverse sewing control rules during reverse sewing, and controlling and adjusting the positions of the intervention point (track point B′ and track point A′) and the end point (track point B and track point A) of the rotation of the stitch length motor 1, a variety of feed dog 5 motion trajectory changes and trajectory fine-tuning can be achieved without exceeding the adjustable stitch length stroke and interfering with other functional actions such as presser foot lifting and thread trimming.

[0080] For example, in the first embodiment, when sewing, the sewing control rule ① and the sewing control rule ② are combined, and the rotation angle area of ​​the needle pitch motor 1 in the track point A′-B interval and the track point B′-A interval is smoothly transitioned. The rotation angle of the needle pitch motor 1 is as follows: Figure 3 As shown, the maximum rotation angle of the needle pitch motor 1 is M and the minimum rotation angle is N. According to this control of the rotation angle of the needle pitch motor 1, the motion trajectory of the feed dog 5 is as follows Figure 4 At this time, the motion track of the feed dog 5 is roughly rectangular.

[0081] Preferably, the needle distance motor 1 is controlled not to rotate in the interval between track points A′-B and track points B′-A, so that the angle of the swing plate seat 6 remains unchanged, that is, the angle of the needle distance motor 1 in the interval between track points A′-B and track points B′-A is controlled at a fixed angle, thereby controlling the heights of track points A, A′, B, and B′, and is more conducive to controlling the angle of the needle distance motor 1 to be able to effectively adjust the needle distance within the angle range (needle distance adjustment area) to avoid interference with other functional actions.

[0082] Preferably, the needle length motor 1 is controlled to have a maximum (forward sewing) / minimum (reverse sewing) angle in the trajectory point A′-B interval and the trajectory point B′-A interval, that is, the needle length motor 1 is controlled to achieve maximum (forward sewing) / minimum (reverse sewing) angle control before and after the start of the vertical straight line segment (segment AA′, segment BB′).

[0083] For example, in the second embodiment, during the positive sewing, the positive sewing control rule ① and the positive sewing control rule ② are combined, and the rotation angle of the needle pitch motor 1 in the track point A′-B interval and the track point B′-A interval is maintained at the maximum rotation angle, and the rotation angle of the needle pitch motor 1 is as follows: Figure 5 As shown, at this time, the maximum rotation angle of the needle distance motor 1 is L and the minimum rotation angle is N. According to this, the rotation angle of the needle distance motor 1 is controlled, and the motion trajectory of the feed dog 5 is obtained as shown in Figure 6As shown. The maximum rotation angle L of the needle pitch motor 1 in the second embodiment is smaller than the maximum rotation angle M of the needle pitch motor 1 in the first embodiment, and will not exceed the maximum position of the needle pitch cam 17. The rotation angle of the needle pitch motor 1 is reduced by nearly half compared with the first embodiment, and the actual motion trajectory of the feed dog 5 does not change much. Therefore, the second embodiment effectively reduces the motor load.

[0084] In the third embodiment, the maximum rotation angle of the needle pitch motor 1 can be further reduced on the basis of the second embodiment, so that the positions of the track points A, A′, B, and B′ can be controlled. The rotation angle of the needle pitch motor 1 is as follows: Figure 7 As shown, at this time, the maximum rotation angle of the needle distance motor 1 is L' and the minimum rotation angle is N. According to this, the rotation angle of the needle distance motor 1 is controlled, and the motion trajectory of the feed dog 5 is obtained as shown in Figure 8 Compared with the first and second embodiments, in the motion trajectory of the feed dog 5 of the third embodiment, the positions of the trajectory points A, A′, B, and B′ are closer to the needle plate plane.

[0085] Therefore, the motor control method of the sewing machine of this embodiment can adjust the rectangular motion trajectory of the feed dog 5 according to the sewing requirements of fabrics of different thicknesses, and can reduce the motor load by reducing the rotation angle of the stitch motor 1.

[0086] Preferably, the rotation angle of the needle pitch motor 1 in the track point A′-B interval and the rotation angle of the needle pitch motor 1 in the track point B′-A interval can also be controlled separately. By separately controlling the rotation angle limit of the needle pitch motor 1 in the track point A′-B interval and the track point A′-B interval, the upper and lower tracks of the needle plate plane can be different, further reducing the motor load.

[0087] For example, in the fourth embodiment, during the sewing process, the sewing control rules ① and ② are combined, and the rotation angle of the needle pitch motor 1 in the interval between the track points A′ and B is maintained at the maximum rotation angle L, and the rotation angle of the needle pitch motor 1 in the interval between the track points B′ and A is maintained at the maximum rotation angle L′. The rotation angle of the needle pitch motor 1 is as follows: Fig. 9 As shown, the minimum rotation angle of the needle distance motor 1 is still N. According to this, the rotation angle of the needle distance motor 1 is controlled, and the motion trajectory of the feed dog 5 is obtained as follows Fig.10 shown.

[0088] In addition, several control methods for reverse stitching are listed below.

[0089] In the fifth embodiment, when reverse sewing, reverse sewing control rule ① and reverse sewing control rule ② are combined, and the rotation angle area of ​​the needle pitch motor 1 in the track point BA′ interval and the track point AB′ interval is smoothly transitioned. The rotation angle of the needle pitch motor 1 is as follows: Fig.11As shown, by controlling the rotation angle of the needle distance motor 1, the motion trajectory of the feed dog 5 is obtained as shown in Fig.12 At this time, the motion track of the feed dog 5 is roughly rectangular.

[0090] In the sixth embodiment, when reverse sewing, reverse sewing control rule ① and reverse sewing control rule ② are combined, and the rotation angle of the needle pitch motor 1 in the track point BA′ interval and the track point AB′ interval is kept at the minimum rotation angle. Fig.13 As shown, by controlling the rotation angle of the needle distance motor 1, the motion trajectory of the feed dog 5 is obtained as shown in Fig.14 shown.

[0091] In the seventh embodiment, the motor control method of the sewing machine of this embodiment obtains a roughly triangular motion trajectory of the feed dog 5, and the rotation angle of the needle pitch motor 1 is as follows: Fig.15 As shown, by controlling the rotation angle of the needle distance motor 1, the motion trajectory of the feed dog 5 is obtained as shown in Fig.16 shown.

[0092] In the eighth embodiment, the combined feed dog 5 motion trajectory is obtained by the motor control method of the sewing machine of this embodiment, and the rotation angle of the needle pitch motor 1 is as follows: Fig.17 As shown, by controlling the rotation angle of the needle distance motor 1, the motion trajectory of the feed dog 5 is obtained as shown in Fig.18 shown.

[0093] It can be understood that the above eight implementation modes are only a few of the feed dog 5 motion trajectories that can be obtained by the motor control method of the sewing machine of this embodiment. In actual application, according to sewing requirements, different styles of feed dog 5 motion trajectories can be achieved by controlling the stitch length motor 1 to work under different working conditions.

[0094] In summary, the motor control method of the sewing machine of the present embodiment adjusts the motion trajectory of the feed dog 5 by adjusting the angle of the swing plate seat 6 during sewing, and there is no need to add an additional motor to control the tooth frame 4. Since the adjustment trajectory is adjusted based on the original elliptical trajectory, the stability of the adjusted trajectory and the cloth feeding force of the feed dog 5 are higher than the mechanism that uses a motor alone to control the motion trajectory of the feed dog 5. The motor control method of the sewing machine of the present embodiment can fine-tune the motion trajectory of the feed dog 5, and can also achieve the adjustment of a variety of different trajectories. In addition, the motor load is reduced by controlling the trajectory in sections. At the same time, the motor control method of the sewing machine of the present embodiment can better adapt to the one-to-two / one-to-three structure, and can achieve trajectory adjustment without affecting other functional actions such as lifting the presser foot and cutting the thread.

[0095] Based on the above-mentioned motor control method for a sewing machine, an embodiment of the present invention further provides a sewing machine. The sewing machine of this embodiment uses the above-mentioned motor control method for a sewing machine of this embodiment to sew.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A motor control method for a sewing machine, the sewing machine comprising: A feeding mechanism is connected between the main shaft and the tooth frame, a feeding tooth is installed on the tooth frame, and the feeding mechanism has a swing plate seat that can rotate to change the angle, and the angle of the swing plate seat determines the needle distance of the sewing machine; A needle pitch motor is connected to the swing plate seat through the needle pitch adjusting mechanism and drives the swing plate seat to rotate; A main motor drives the main shaft to rotate, and drives the tooth rack and the feeding tooth to move through the feeding mechanism; In one stitch length sewing cycle, when the angle of the swing plate seat remains unchanged, the motion trajectory of the feed dog is an elliptical trajectory line, and the elliptical trajectory line passes through the trajectory point Z at the highest position above the needle plate, the trajectory point O at the height of the needle plate, the trajectory point Z′ at the lowest position below the needle plate, and the trajectory point O′ at the height of the needle plate; Characterized in that, the motor control method of the sewing machine is: On the elliptical trajectory line, take trajectory point A located in the trajectory point ZO interval, trajectory point A′ located in the trajectory point OZ′ interval, trajectory point B located in the trajectory point Z′-O′ interval, and trajectory point B′ located in the trajectory point O′-Z interval; In one stitch sewing cycle, the stitch motor is controlled to rotate in the track point AA' interval and the track point BB' interval. The angle of the swing plate seat is changed, thereby changing the shape of the motion trajectory of the feed dog; One of the track point A and the track point A′, one of the track point B and the track point B′ is used as the starting point of the needle pitch motor rotation, and the other of the track point A and the track point A′, the other of the track point B and the track point B′ is used as the ending point of the needle pitch motor rotation; The positions of the intervention point and the end point of the rotation of the stitch length motor are controlled so that the stitch length motor rotates within an angle range that can effectively adjust the stitch length.

2. The motor control method of a sewing machine according to claim 1, characterized in that: In the interval between track points A′-B and track points B′-A, the needle distance motor is controlled not to rotate, so that the angle of the swing plate seat remains unchanged.

3. The motor control method of a sewing machine according to claim 2, characterized in that: The needle pitch motor is controlled to have a maximum / minimum rotation angle in the track point A′-B interval and the track point B′-A interval.

4. The motor control method of a sewing machine according to claim 2, characterized in that: The rotation angle of the needle pitch motor in the track point A′-B interval and the rotation angle of the needle pitch motor in the track point B′-A interval are controlled separately.

5. A sewing machine, characterized in that: The sewing machine performs sewing using the motor control method for a sewing machine as claimed in any one of claims 1 to 4.

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