Sewing machine

Abstract

This sewing machine (100) comprises: a needle vertical movement mechanism that vertically moves a sewing needle (11) by means of a sewing machine motor (16); an upper feed mechanism (40) that, on both left and right sides of the needle location position, causes conveyance belts (41), (42) individually to abut from above to feed a workpiece on a needle plate (101); detection units (48), (49), (762) for detecting the height of the workpiece at the feed position of the left conveyance belt (41) and the height of the workpiece at the feed position of the right conveyance belt (42), or detecting the difference between said heights; and a control device (90) that controls the operation of the needle vertical movement mechanism and the upper feed mechanism (40). On the basis of the detection by the detection units (48), (49), and (762), the control device (90) performs control for adjusting the driving of the feeding of the left and right conveyance belts (41, 42) of the upper feed mechanism (40).

Description

sewing machine

[0001] The present disclosure relates to sewing machines.

[0002] In some sewing machines, upper feed sections are provided above the needle plate on both the left and right sides of the needle drop position, and the workpiece is fed by a conveyor belt provided in each upper feed section. In this sewing machine, a detection arm directly contacts the workpiece on the needle plate from above to detect the thickness of the workpiece (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 2006-158497

[0004] In the above sewing machine, the thickness of the sewing material is detected at one point on the sewing material, so if there is a difference in the thickness of the sewing material on either side of the needle drop position where the left and right upper feed sections perform belt feed, it is not possible to detect this.

[0005] The present disclosure aims to properly feed the sewing material when there is a difference in height between the sewing material and the feeding positions of the left and right conveyor belts arranged on both sides of the needle drop position.

[0006] A sewing machine according to one aspect of the present disclosure comprises a needle up / down movement mechanism that moves the sewing needle up and down using a sewing machine motor; an upper feed mechanism that feeds the workpiece on the needle plate by contacting a conveyor belt from above on both the left and right sides of the needle drop position; a detection unit that detects the height of the workpiece at the feed position of the conveyor belt on the left side and the height of the workpiece at the feed position of the conveyor belt on the right side, or detects the difference between these; and a control device that controls the operation of the needle up / down movement mechanism and the upper feed mechanism, and the control device adjusts the drive of the feed of the conveyor belts on the left and right sides of the upper feed mechanism based on the detection by the detection unit.

[0007] According to the sewing machine of the present disclosure, when there is a difference in height of the workpiece at each feed position of the left and right conveyor belts arranged on both sides of the needle drop position, it is possible to feed the workpiece appropriately.

[0008] FIG. 1 is a rear view of a sewing machine according to an embodiment of the present disclosure. FIG. 2 is a left side view of the sewing machine. FIG. 3 is a perspective view of the sewing machine. FIG. 4 is a perspective view of the upper left end of the sewing machine bed, with the presser foot not shown. FIG. 5 is a perspective view of a guide frame of a lower feed mechanism. FIG. 6 is a perspective view of a feed mechanism in which four conveyor belts are in a front-rear differential feed state. FIG. 7 is a perspective view of a feed mechanism in which four conveyor belts are in a left-right differential feed state. FIG. 8 is a perspective view of a presser foot mechanism that presses down a sewing object on the needle plate from above, and its periphery. FIG. 9 is a rear view of the presser foot mechanism and its periphery. FIG. 10 is a right side view of the presser foot mechanism and its periphery. FIG. 11 is a block diagram showing a control system of the sewing machine. FIG. 12 is a rear view of the presser foot mechanism and its periphery, showing an example in which a distance sensor is used as a detection unit. FIG. 13 is a perspective view of the upper left end of the sewing machine bed, showing an example in which a needle hole is formed directly in the needle plate.

[0009] [Overview of an embodiment of the present disclosure] A sewing machine 100 according to an embodiment of the present disclosure will now be described in detail. FIG. 1 is a rear view of the sewing machine 100, FIG. 2 is a left side view of the sewing machine 100, and FIG. 3 is a perspective view of the sewing machine 100. Hereinafter, the downstream side in the feed direction of the sewing workpiece (see FIG. 12 ) will be referred to as the "front," the upstream side in the feed direction as the "rear," the left-hand side when facing forward as the "left," the right-hand side as the "right," the vertically upward direction as the "up," and the vertically downward direction as the "down." These directions are relative directions set for the sewing machine 100 illustrated in FIGS. 1 to 13 . The front-to-rear direction, the left-to-right direction, and the up-to-down direction are perpendicular to one another. In the following description, it is assumed that the sewing machine 100 is installed on a horizontal surface, and the front-to-rear direction and the left-to-right direction are horizontal.

[0010] A so-called lockstitch sewing machine is exemplified as a sewing machine 100 according to an embodiment of the present disclosure. As shown in FIGS. 1 to 3 , the sewing machine 100 includes a sewing machine frame 110, a needle up-and-down movement mechanism, a bottom feed mechanism 20 as a feed device, an top feed mechanism 40 as a feed device, a presser foot mechanism 70 as a presser foot mechanism, a shuttle mechanism, a positioning ruler 50 (see FIG. 9 ), and a retraction mechanism 60 (see FIG. 8 ). The needle up-and-down movement mechanism applies up-and-down movement to the sewing needle 11. Details of the needle up-and-down movement mechanism will be described later. The bottom feed mechanism 20 applies a feed movement from below to the workpiece on the needle plate 101. The top feed mechanism 40 applies a feed movement from above to the workpiece on the needle plate 101. The presser foot mechanism 70 applies pressure to the workpiece on the needle plate 101. The shuttle mechanism captures the loop of the upper thread from the sewing needle 11 and entangles the bobbin thread therein to form a stitch. The positioning ruler 50 abuts against the side edge of the sewing material to determine the edge width, which is the distance from that side edge to the seam. The retraction mechanism 60 holds the belt guide 44 of the upper feed mechanism 40 in a retracted position to avoid interference when using the positioning ruler 50. The sewing machine 100 is equipped with various components such as a thread take-up mechanism and thread tensioner that are equipped in general lockstitch sewing machines, but these are well known and will not be described here.

[0011] [Sewing Machine Frame] As shown in Fig. 1, the sewing machine frame 110 supports or stores each component of the sewing machine 100 described above. The sewing machine frame 110 has a sewing machine bed section 111, an upright body section 112, and a sewing machine arm section 113. The sewing machine bed section 111 is located at the bottom of the sewing machine 100 and extends in the left-right direction of the sewing machine 100 in Fig. 1. The upright body section 112 stands upright from the right end of the sewing machine bed section 111. The sewing machine arm section 113 extends leftward from the upper end of the upright body section 112.

[0012] [Needle up / down movement mechanism] Figure 4 is a perspective view showing the top surface of the left end of the sewing machine bed 111. The presser foot, which will be described later, is not shown in the sewing machine bed 111 shown in Figure 4. The needle up / down movement mechanism is disposed inside the sewing machine arm 113, along the left-right direction of the sewing machine arm 113, and has an upper shaft that is rotationally driven by the sewing machine motor 16 (see Figure 11). As shown in Figures 1 to 4, the needle up / down movement mechanism further includes a needle bar 12 that holds the sewing needle 11 at its lower end, and a crank mechanism that converts the rotational force of the upper shaft into a reciprocating drive force for up / down movement and transmits it to the needle bar. The upper shaft and crank mechanism are well known and are therefore not shown.

[0013] The needle bar 12 extends in the vertical direction of the sewing needle 11 and is supported so as to be movable up and down at the lower left end of the sewing machine arm portion 113. The sewing needle 11 is held at the lower end of the needle bar 12 and moves up and down together with the needle bar 12. A needle plate 101 made of a horizontal flat plate is provided on the upper surface of the sewing machine bed portion 111 and below the needle bar 12.

[0014] A compound opening 102 is formed at the needle drop position of the sewing needle 11 relative to the needle plate 101. A pinhole member 30 having a pinhole 13, and a rear-left lower belt 21, a front-left lower belt 22, a front-right lower belt 23, and a rear-right lower belt 24 of the lower feed mechanism 20 (described later) are disposed in the compound opening 102 of the needle plate 101 so as to be exposed upward. Hereinafter, the rear-left lower belt 21, the front-left lower belt 22, the front-right lower belt 23, and the rear-right lower belt 24 will also be referred to as the lower belts 21 to 24. In other words, the compound opening 102 is an opening formed by integrally combining a plurality of rectangular openings through which the pinhole member 30 and the lower belts 21 to 24 are exposed.

[0015] 2 and 3, the shuttle mechanism includes an inner shuttle 14 and an outer shuttle 15 provided below the needle eye member 30 of the needle plate 101, and a shuttle shaft (not shown) that rotates the outer shuttle 15. The shuttle shaft is rotatably supported within the sewing machine bed portion 111 with its axial direction aligned in the left-right direction. Rotation of the shuttle shaft about its own axis, which is increased twice as fast as that of the upper shaft, is input to the shuttle shaft from the above-mentioned upper shaft via a gear mechanism or a belt mechanism.

[0016] The inner shuttle 14 is housed inside the outer shuttle 15. The inner shuttle 14 houses a bobbin (not shown) for supplying bobbin thread. The outer shuttle 15 is connected to the left end of the shuttle shaft and rotates around the inner shuttle 14. The inner shuttle 14 is restricted from rotating together with the outer shuttle 15. The outer shuttle 15 has a point on its outer periphery for capturing the loop of upper thread from the sewing needle 11. When the outer shuttle 15 rotates, the point captures the loop of upper thread and allows the bobbin thread unwound from inside the inner shuttle 14 to pass through it. The outer shuttle 15 and inner shuttle 14 are housed and arranged inside a substantially cylindrical guide frame 29 of the bottom feed mechanism 20, which will be described later.

[0017] [Downward Feed Mechanism] Fig. 5 is a perspective view showing the guide frame 29 of the downward feed mechanism 20, and Figs. 6 and 7 are perspective views showing the downward feed mechanism 20. Figs. 6 and 7 show different cases in which the lower belts 21 to 24, which will be described later, are looped over in different states. The downward feed mechanism 20 will be described in detail below with reference to Figs. 1 to 7.

[0018] As shown in the drawings, the bottom feed mechanism 20 has bottom belts 21 to 24 as conveyor belts, a first motor 25, a second motor 26, rotary shafts 27 and 28, a first pulley 31, and a second pulley 32. The bottom feed mechanism 20 further has a guide frame 29 that guides the bottom belts 21 to 24 so that they come into contact with the lower surface of the workpiece, a first pressure mechanism 33, and a second pressure mechanism 34.

[0019] The first motor 25 and the second motor 26 are both motors whose operating amounts can be arbitrarily controlled. The first motor 25 and the second motor 26 are, for example, stepping motors or servo motors. The first motor 25 and the second motor 26 are arranged in a line up front and rear inside the right end of the sewing machine bed portion 111, with their output shafts facing leftward. A first pulley 31 is connected to the output shaft of the first motor 25 via a rotating shaft 27. A second pulley 32 is connected to the output shaft of the second motor 26 via a rotating shaft 28.

[0020] The rotary shafts 27, 28 are both parallel to the left-right direction of the sewing machine bed 111 and rotatably supported within the sewing machine bed 111. The first pulley 31 and the second pulley 32 are supported within the left end of the sewing machine bed 111 so as to be rotatable about axes whose rotation centers are aligned along the left-right direction of the sewing machine bed 111. The first pulley 31 and the second pulley 32 are respectively rotated by the first motor 25 and the second motor 26 via the rotary shafts 27, 28. The first pulley 31 and the second pulley 32 are arranged so as to overlap when viewed from the front-to-rear direction. That is, the first pulley 31 and the second pulley 32 are at the same height within the sewing machine bed 111 and in the same position within the sewing machine bed 111 in the left-to-right direction. The first pulley 31 is arranged in front of the second pulley 32 within the sewing machine bed 111.

[0021] Figure 6 shows a state in which the front-left lower belt 22 and the front-right lower belt 23, which are fed on the front side of the needle drop position, are looped around the first pulley 31, and the rear-left lower belt 21 and the rear-right lower belt 24, which are fed on the rear side, are looped around the second pulley 32. Figure 7 shows a state in which the rear-left lower belt 21 and the front-left lower belt 22, which are fed on the left side of the needle drop position, are looped around the first pulley 31, and the front-right lower belt 23 and the rear-right lower belt 24 are looped around the second pulley 32. As shown in Figures 6 and 7, both the first pulley 31 and the second pulley 32 can loop all of the lower belts 21, 22, 23, and 24 arranged in parallel in the left-right direction. That is, the first pulley 31 has, on its outer circumferential surface, a left groove 311 for looping the rear-left lower belt 21 or the front-left lower belt 22 therethrough, and a right groove 312 for looping the front-right lower belt 23 or the rear-right lower belt 24 therethrough. The second pulley 32 has, on its outer circumferential surface, a left groove 321 for passing the rear-left lower belt 21 or the front-left lower belt 22 therethrough, and a right groove 322 for passing the front-right lower belt 23 or the rear-right lower belt 24 therethrough. Each of the lower belts 21 to 24 has the same width, and the left grooves 311, 321 and the right grooves 312, 322 each have a width equivalent to at least two belts. This allows each of the lower belts 21 to 24 to be passed over either the first pulley 31 or the second pulley 32 as appropriate.

[0022] Each of the lower belts 21, 22, 23, and 24 is an endless loop and is stretched between the guide frame 29 and the first pulley 31 or between the guide frame 29 and the second pulley 32. The lower belts 21, 22, 23, and 24 are arranged in parallel in order from left to right in FIG.

[0023] 1 and 2, the guide frame 29 (guide member) is disposed so as to substantially coincide with the first pulley 31 and the second pulley 32 in the left-right direction, and is disposed between the first pulley 31 and the second pulley 32 in the front-rear direction, as shown in Fig. 2. Furthermore, the guide frame 29 is disposed above the first pulley 31 and the second pulley 32 and immediately below the needle plate 101. As shown in Fig. 5, the guide frame 29 has a bracket portion 295 for fixing the guide frame 29 to the inside of the sewing machine bed portion 111, and a cylindrical main body portion 296 for guiding each of the lower belts 21 to 24.

[0024] The guide frame 29 is disposed directly below the needle plate 101 with the central axis of the main body 296 oriented in the left-right direction of the sewing machine bed 111. An engagement groove 297 is formed on the outer peripheral surface of the main body 296, at the center of the upper part of the main body 296 in the left-right direction, along the front-rear direction of the main body 296. A plate-shaped pinhole member 30 that is elongated in the front-rear direction is disposed inside the engagement groove 297. The pinhole member 30 has a needle hole 13 that penetrates the pinhole member 30 from top to bottom at the needle drop position of the sewing needle 11. The pinhole member 30 is connected to a needle up-and-down movement mechanism (not shown). The needle up-and-down movement mechanism uses the above-mentioned sewing machine motor 16 as a drive source to move the pinhole member 30 up and down at the same cycle as the sewing needle 11. The pinhole member 30 moves up and down in the opposite phase to the sewing needle 11 by this needle up-and-down movement mechanism. That is, the surface of the needle hole member 30 where the needle hole 13 is formed is at its highest position in the phase where the sewing needle 11 is at its bottom dead center, and at its lowest position in the phase where the sewing needle 11 is at its top dead center. The highest position of the surface where the needle hole 13 is formed is at the same height as or slightly higher than the top surface of the needle plate 101. The lowest position of the surface where the needle hole 13 is formed is the position that is lowest below the top surface of the needle plate 101.

[0025] The main body 296 also feeds the material to be sewn by sliding the lower belts 21 to 24 in the circumferential direction of the main body 296 on the upper part of its outer circumferential surface. For this reason, a first guide portion 291, a second guide portion 292, a third guide portion 293, and a fourth guide portion 294 for guiding the lower belts 21 to 24 are provided on the upper part of the outer circumferential surface of the main body 296. The first guide portion 291 is provided to the left rear of the needle hole 13, the second guide portion 292 is provided to the left front of the needle hole 13, the third guide portion 293 is provided to the right front of the needle hole 13, and the fourth guide portion 294 is provided to the right rear of the needle hole 13. The first guide portion 291 to the fourth guide portion 294 are all convex ridges extending in the front-to-rear direction, and have widths in the left-to-right direction that are equal to or slightly wider than those of the lower belts 21 to 24. The rear ends of the first guide portion 291 to the fourth guide portion 294 slope so that the amount of protrusion radially outward relative to the outer circumferential surface of the main body portion 296 gradually increases toward the front. Furthermore, the front ends of the first guide portion 291 to the fourth guide portion 294 slope so that the amount of protrusion radially outward relative to the outer circumferential surface of the main body portion 296 gradually decreases toward the front.

[0026] The first guide portion 291 is located to the left of the needle eye 13 and rearward of the center of the needle eye 13 over substantially its entire length. The first guide portion 291 has a flat, horizontal guide surface 291a located forward of the portion of the main body 296 that protrudes radially outward most. In FIG. 5 , the guide surface 291a and guide surfaces 292a, 293a, and 294a, which will be described later, are each indicated by polka dots. The guide surface 291a is positioned to face the compound opening 102 of the needle plate 101 when viewed from above the sewing machine bed 111. The guide surface 291a is configured so that the outer surface of the rear-left lower belt 21, which slides over the guide surface 291a, is slightly higher than the upper surface of the needle plate 101. The guide surface 291a is configured so that the front end of the guide surface 291a is located slightly rearward of the center of the needle eye 13, and the rear-left lower belt 21 abuts against the workpiece rearward of the center of the needle eye 13.

[0027] The second guide portion 292 is located to the left of the needle eye 13 and to the right of the first guide portion 291, and is located forward of the center of the needle eye 13 over substantially its entire length. The second guide portion 292 has a flat and horizontal guide surface 292a rearward of the portion of the main body 296 that protrudes most radially outward. The guide surface 292a is positioned to face the compound opening 102 of the needle plate 101 when viewed from above the sewing machine bed 111. The guide surface 292a is configured so that the outer surface of the front-left lower belt 22, which slides over and passes over the guide surface 292a, is slightly higher than the upper surface of the needle plate 101. The guide surface 292a is formed so that the rear end of the guide surface 292a is located slightly forward of the center of the needle eye 13, and the front-left lower belt 22 abuts against the workpiece forward of the center of the needle eye 13.

[0028] The third guide portion 293 is located to the right of the needle eye 13 and forward of the center of the needle eye 13 over substantially its entire length. The third guide portion 293 has a flat and horizontal guide surface 293a rearward of the portion of the main body 296 that protrudes most radially outward. The guide surface 293a is positioned to face the compound opening 102 of the needle plate 101 when viewed from above the sewing machine bed 111. The guide surface 293a is set so that the outer surface of the front right lower belt 23, which slides over the guide surface 293a, is slightly higher than the upper surface of the needle plate 101. The guide surface 293a is formed so that the rear end of the guide surface 293a is located slightly forward of the center of the needle eye 13 and the front right lower belt 23 abuts against the material to be sewn forward of the center of the needle eye 13.

[0029] The fourth guide portion 294 is located to the right of the needle eye 13 and the third guide portion 293 and rearward of the center of the needle eye 13 over substantially its entire length. The fourth guide portion 294 has a flat and horizontal guide surface 294a located forward of the portion of the main body 296 that protrudes radially outward most. The guide surface 294a is positioned to face the compound opening 102 of the needle plate 101 when viewed from above the sewing machine bed 111. The guide surface 294a is configured so that the outer surface of the rear right lower belt 24, which slides over and passes over the guide surface 294a, is slightly higher than the upper surface of the needle plate 101. The guide surface 294a is formed so that the front end of the guide surface 294a is located slightly rearward of the center of the needle eye 13 and the rear right lower belt 24 abuts against the workpiece rearward of the center of the needle eye 13.

[0030] The guide surfaces 291a, 294a are provided rearward of the center of the needle hole 13, and the guide surfaces 292a, 293a are provided forward of the center of the needle hole 13. Therefore, when a speed difference (conveyance amount difference) is provided between the rear left lower belt 21 and rear right lower belt 24 on the rear side and the front left lower belt 22 and front right lower belt 23 on the front side, the lower belts 21 to 24 do not interfere with each other, and a conveying force due to the front and rear feed speed difference (conveyance amount difference) can be applied to the sewn material. Therefore, targeted stitches can be formed in the differential feed in the front and rear direction, and it is possible to improve the sewing quality.

[0031] The first pressure mechanism 33 applies tension to all of the lower belts 21 to 24 that are stretched between the guide frame 29 and the first pulley 31, thereby preventing slack from occurring in the stretched lower belts 21 to 24. As shown in Figures 2, 3 and 6, the first pressure mechanism 33 has a left pressure roller 331, a right pressure roller 332, a support plate 333, and a base block 334.

[0032] The support plate 333 is a long, flat plate extending along a plane including the front-rear and up-down directions of the sewing machine 100, and is supported by the base block 334 with its longitudinal direction facing diagonally upward toward the front. Furthermore, the support plate 333 concentrically and rotatably supports the left pressure roller 331 on the left surface at the upper end of the support plate 333 and the right pressure roller 332 on the right surface at the upper end of the support plate 333. The support plate 333 is disposed so that the left pressure roller 331 and the right pressure roller 332 abut against the outer surface of the belt extending between the guide frame 29 and the first pulley 31 from below the rear of the belt.

[0033] The base block 334 is shared with the second pressure mechanism 34 (described later) and supports the components of the first pressure mechanism 33 and the second pressure mechanism 34. The base block 334 is fixed below the guide frame 29 within the sewing machine bed 111 and is mounted on the sewing machine bed 111. The support plate 333 has elongated holes aligned with the longitudinal direction of the support plate 333. The support plate 333 is fastened and fixed to the base block 334 with two bolts inserted through the elongated holes. The longitudinal direction of the support plate 333 is oriented approximately perpendicular to the belt stretched around the first pulley 31. Therefore, by loosening the bolts and moving the support plate 333 along the elongated holes, the pressure contact force of the left pressure roller 331 and the right pressure roller 332 against the belt can be adjusted. In other words, the tension of the belt passing between the guide frame 29 and the first pulley 31 can be adjusted.

[0034] As shown in Figure 6, the left pressure roller 331 and the right pressure roller 332 have the same outer diameter and are supported by a support plate 333 so as to be rotatable about the same axis along the left-right direction of the lower feed mechanism 20. Furthermore, the left and right widths of the left pressure roller 331 and the right pressure roller 332 are both twice or more the width of each of the lower belts 21 to 24. This allows the left pressure roller 331 to come into contact with either the rear-left lower belt 21 or the front-left lower belt 22 that are stretched between the guide frame 29 and the first pulley 31. Similarly, the right pressure roller 332 can come into contact with either the front-right lower belt 23 or the rear-right lower belt 24 that are stretched between the guide frame 29 and the first pulley 31.

[0035] The second pressure mechanism 34 applies tension to all of the lower belts 21 to 24 that are stretched between the guide frame 29 and the second pulley 32, thereby preventing slack from occurring in the stretched lower belts 21 to 24. As shown in Figures 2, 3 and 6, the second pressure mechanism 34 has a left pressure roller 341, a right pressure roller 342, a support plate 343, and the base block 334 described above.

[0036] The support plate 343 has the same structure as the support plate 333 described above, and is supported by the base block 334 with its longitudinal direction facing diagonally upward and rearward. The support plate 343 also concentrically and rotatably supports the left pressure roller 341 on the left surface of the upper end of the support plate 343 and the right pressure roller 342 on the right surface of the upper end of the support plate 343. The support plate 343 is disposed so that the left pressure roller 341 and the right pressure roller 342 abut against the outer surface of the belt spanning between the guide frame 29 and the second pulley 32 from above the rear of the belt.

[0037] The support plate 343 also has an elongated hole, and the support plate 343 can be moved along the elongated hole. This makes it possible to adjust the pressure of the left pressure roller 341 and the right pressure roller 342 on the belt wound around the second pulley 32. Therefore, the tension of the belt passing between the guide frame 29 and the second pulley 32 can be adjusted.

[0038] As shown in Figure 6, the left pressure roller 341 and the right pressure roller 342 have the same outer diameter and are supported by a support plate 343 so as to be rotatable about the same axis along the left-right direction of the lower feed mechanism 20. Furthermore, the left and right widths of the left pressure roller 341 and the right pressure roller 342 are both twice or more the widths of the lower belts 21 to 24. This allows the left pressure roller 341 to come into contact with either the rear-left lower belt 21 or the front-left lower belt 22 that are stretched between the guide frame 29 and the second pulley 32. Similarly, the right pressure roller 342 can come into contact with either the front-right lower belt 23 or the rear-right lower belt 24 that are stretched between the guide frame 29 and the second pulley 32.

[0039] The left pressure roller 331 of the first pressure mechanism 33 and the left pressure roller 341 of the second pressure mechanism 34 can both be brought into contact with the rear-left lower belt 21 and the front-left lower belt 22. Similarly, the right pressure roller 332 of the first pressure mechanism 33 and the right pressure roller 342 of the second pressure mechanism 34 can both be brought into contact with the front-right lower belt 23 and the rear-right lower belt 24. Therefore, regardless of whether each of the lower belts 21 to 24 is wound around the first pulley 31 or the second pulley 32, tension is applied by either the first pressure mechanism 33 or the second pressure mechanism 34.

[0040] 6 and 7, by loosening the bolts and retracting the left pressure roller 331, the right pressure roller 332, the left pressure roller 341, and the right pressure roller 342, the lower belts 21 to 24 can be easily removed and relocated from the first pulley 31 or the second pulley 32. Therefore, sewing can be easily selected between the hanging state shown in FIG. 6 and the hanging state shown in FIG. 7.

[0041] The state in which the lower belts 21 to 24 are passed over in Fig. 6 is a front-rear differential feed state. For example, in the front-rear differential feed state in Fig. 6, it is possible to perform so-called shirring stitches. Shirring stitches are a sewing method in which the front side of the needle drop position is fed faster than the rear side. In addition, in the front-rear differential feed state, it is also possible to perform sewing that applies tension to the sewn material by feeding the front side of the needle drop position slower than the rear side.

[0042] The state in which the lower belts 21 to 24 are looped around in Fig. 7 is a left-right differential feed state. For example, in the left-right differential feed state in Fig. 7, if the left side is fed quickly, a curved stitch that curves to the right can be performed, and if the right side is fed quickly, a curved stitch that curves to the left can be performed. In addition, since the curvature of the curve to be sewn can be changed depending on the difference in speed between the left and right sides (difference in the feed amount), it is possible to perform a variety of curved stitches.

[0043] [Presser Mechanism] Figure 8 is a perspective view showing the presser mechanism 70 and its periphery as a presser mechanism that presses down the sewing material on the needle plate 101 from above. Figure 9 is a rear view showing the presser mechanism 70 and its periphery. Figure 10 is a right side view showing the presser mechanism 70 and its periphery. Note that the positioning ruler 50 and its support mechanism 53, which will be described later, are not shown in Figure 8.

[0044] The presser foot mechanism 70 has a presser foot 71, a presser bar 72, a mounting base 74, a presser motor 73 (see FIG. 11), and a height sensor 762 (see FIG. 11) that serves as a presser height detector. As shown in FIG. 8, the presser bar 72 is disposed adjacent to the needle bar 12 in the forward direction, and is supported inside the sewing machine arm portion 113 so as to be vertically movable along the vertical direction of the presser foot mechanism 70.

[0045] The upper end of the presser bar 72 is pressed downward by a presser spring (not shown) inside the sewing machine arm 113. The amount of expansion and contraction of the presser spring can be adjusted by a presser motor, the amount of movement of which can be freely controlled. Therefore, by controlling the presser motor, the presser foot 71 can be set to any desired pressure. The presser motor also controls the lifting operation of the presser foot 71, switching between a presser foot height at which the presser foot 71 presses down on the material to be sewn on the needle plate 101 and a released height at which the presser foot 71 is spaced apart.

[0046] In addition, the presser bar 72 is provided with a height sensor 762 that detects the height of the presser bar 72. Therefore, after the presser foot 71 pressure has been set to a specified value, if the height of the presser foot 71 changes due to a change in the thickness of the material to be sewn, the presser motor is controlled so that the amount of expansion and contraction of the presser spring does not change, thereby making it possible to maintain the presser foot pressure at a constant set value.

[0047] The presser foot 71 is attached to the lower end of the presser bar 72 via a mounting base 74. The mounting base 74 is a block with horizontal, flat upper and lower surfaces. The mounting base 74 has an insertion hole that penetrates from the top to the bottom, into which the presser bar 72 can be inserted. The mounting base 74 is fixed to the lower end of the presser bar 72 by, for example, fastening screws. In addition, the lower end of a link member 474 of the upper feed mechanism 40 (described later) is connected to the front end of the mounting base 74 so as to be rotatable about an axis that extends in the left-right direction of the presser foot mechanism 70.

[0048] The presser foot 71 is disposed above the composite opening 102 of the needle plate 101. The presser foot 71 presses down on the workpiece from above, appropriately transmitting the conveying force of the lower belts 21 to 24 to the workpiece. The presser foot 71 also supports the upper left belt 41 and upper right belt 42 of the upper feed mechanism 40 via the left belt guide 43 and the right belt guide 44 so that they can be conveyed. Hereinafter, the upper left belt 41 and upper right belt 42 will be referred to as the upper belts 41, 42, or the left and right upper belts 41, 42. The presser foot 71 also functions to press the upper belts 41, 42 against the workpiece, appropriately transmitting the conveying force of the upper belts 41, 42 to the workpiece.

[0049] As shown in FIGS. 8 and 9, the presser foot 71 has a bottom plate 711 that presses down on the sewing object from above, and a connecting portion 712 that is attached to the lower end of the presser bar 72.

[0050] As shown in Figure 8, the bottom plate 711 has a smooth bottom surface and is formed in a so-called boat shape with the upstream side in the cloth feeding direction (the rear end of the bottom plate 711) curved upward. The connecting part 712 is erected on the upper surface of the front end of the bottom plate 711 and is connected to the bottom plate 711 so as to be able to swing somewhat around an axis extending in the left-right direction. The upper part of the connecting part 712 abuts against the bottom surface of the mounting base 74 and is fixed to the left side surface of the mounting base 74 by, for example, screws. The connecting part 712 may be joined to the mounting base 74 by welding or the like, or the connecting part 712 and the mounting base 74 may be formed as a single integrated member.

[0051] 1, 2, 8 and 9, the upper feed mechanism 40 includes an upper left belt 41 and an upper right belt 42 as conveying belts, the left belt guide 43 and the right belt guide 44 described above, an upper left motor 45 that serves as a drive source for feeding the upper left belt 41, an upper right motor 46 that serves as a drive source for feeding the upper right belt 42, and a guide mechanism 47 that guides the upper belts 41 and 42 from the upper motors 45 and 46 to the presser foot 71.

[0052] The left belt guide 43 is mounted on the left side of the presser foot 71, and the right belt guide 44 is mounted on the right side of the presser foot 71. The left belt guide 43 is rotatably attached to the left side surface of the lower part of the connecting part 712 of the presser foot 71 by a support shaft that extends in the left-right direction, and the right belt guide 44 is rotatably attached to the right side surface of the lower part of the connecting part 712 of the presser foot 71 by a support shaft that extends in the left-right direction.

[0053] As shown in Figure 8, in a side view, each belt guide 43, 44 has a front end that extends diagonally upward toward the front, a point just before the rear end that is closest to the needle plate 101, and a rear end that is raised diagonally upward toward the rear. The left belt guide 43 has a feed roller 432 at its rear end that is rotatable about a shaft that extends in the left-right direction of the left belt guide 43. The right belt guide 44 has a feed roller 442 at its rear end that is rotatable about a shaft that extends in the left-right direction of the right belt guide 44. The left endless annular upper belt 41 is guided to pass between the left belt guide 43 and the side surface of the presser foot 71. The right endless annular upper belt 42 is guided to pass between the right belt guide 44 and the side surface of the presser foot 71. That is, the left and right upper belts 41, 42 are folded downward from above the feed rollers 432, 442 along the rear outer periphery, guided so as to proceed forward along the portion of each belt guide 43, 44 closest to the needle plate 101, and then pass through in an upward, front-facing direction. As each upper belt 41, 42 proceeds forward along the portion of each belt guide 43, 44 closest to the needle plate 101, it contacts the workpiece on the needle plate 101 and feeds the workpiece forward. Note that the position at which the upper left belt 41 contacts the workpiece overlaps the position at which the front lower left belt 22 contacts the workpiece in a plan view. The workpiece is sandwiched between these belts for feeding. Similarly, the position at which the upper right belt 42 contacts the workpiece overlaps the position at which the front lower right belt 23 contacts the workpiece in a plan view. The workpiece is sandwiched between these belts for feeding.

[0054] As described above, each belt guide 43, 44 is pivotally supported on the presser foot 71 by a support shaft (not shown) extending in the left-right direction. One end of each tension spring 433, 443 is connected to a shaft 434, 444 provided at the front end of each belt guide 43, 44. The other end of the tension spring 433 is connected to a shaft 745 provided on the left side surface of the mount 74, applying upward tension to the front end of the left belt guide 43. The other end of the tension spring 443 is connected to a shaft 746 provided on the right side surface of the mount 74, applying upward tension to the front end of the right belt guide 44. Therefore, the rear end of each belt guide 43, 44 is biased to rotate downward, and a pressing force toward the needle plate 101 is applied to each upper belt 41, 42 moving forward along the portion closest to the needle plate 101. Therefore, a pressure is applied to each of the upper belts 41 and 42 against the workpiece on the needle plate 101 .

[0055] Furthermore, because the rear ends of the belt guides 43, 44 are pressed against the material to be sewn on the needle plate 101, the belt guides 43, 44 rotate about their support shafts in accordance with changes in the thickness of the material to be sewn, causing changes in the height of the rear ends. In the sewing machine 100, as shown in Figures 9 to 11, the axis-to-axis distance between the shafts 434, 444 and the shafts 745, 746 located at both ends of the tension springs 433, 443 of the belt guides 43, 44 is detected by left and right potentiometers 48, 49. The detection by these left and right potentiometers 48, 49 makes it possible to detect changes in the height (vertical position) of the rear ends of the belt guides 43, 44 caused by the rotation of the belt guides 43, 44.

[0056] The upper-left motor 45 and the upper-right motor 46 are motors whose rotation speeds can be controlled, such as DC motors, AC motors, stepping motors, etc. The upper-left motor 45 is supported on the front side of the left end of the sewing machine arm 113 via a motor bracket 451 with its output shaft facing left. The upper-right motor 46 is supported above the upper-left motor 45 on the front side of the left end of the sewing machine arm 113 via a motor bracket 451 with its output shaft facing left.

[0057] The output shaft of the upper left motor 45 is equipped with a motor pulley 452. One end of the upper left belt 41 is wound around the motor pulley 452. The output shaft of the upper right motor 46 is equipped with a motor pulley 462, and one end of the upper right belt 42 is wound around the motor pulley 462.

[0058] The upper-left belt 41 is an endless loop. One end of the upper-left belt 41, when stretched out, is hung around a motor pulley 452 of the upper-left motor 45, and the other end is hung around a feed roller 432 of the belt guide 43. The upper-right belt 42 is also an endless loop. One end of the upper-right belt 42, when stretched out, is hung around a motor pulley 462 of the upper-right motor 46, and the other end is hung around the feed roller 442 at the rear end of the belt guide 44 described above.

[0059] When viewed from the left-right direction, the path of the upper left belt 41 from the motor pulley 452 to the feed roller 432 and the path of the upper right belt 42 from the motor pulley 462 to the feed roller 442 overlap, except for the areas around the motor pulleys 452 and 462. The upper right belt 42 is disposed on the right side of the upper left belt 41.

[0060] 2, the guide mechanism 47 guides the upper-left belt 41 and the upper-right belt 42 along their respective paths. The guide mechanism 47 has a pair of first tension rollers 471 aligned laterally, a pair of second tension rollers 472 aligned laterally, a guide arm 475 made up of upper and lower link members 473, 474, and a plurality of guide rollers 476 rotatably provided at various portions on the paths of the upper belts 41, 42.

[0061] The pair of first tension rollers 471 are disposed below the motor pulley 452. The pair of second tension rollers 472 are disposed between the motor pulley 452 and the pair of first tension rollers 471. The pair of first tension rollers 471 are tension rollers that are rotatable about an axis that aligns with the left-right direction of the sewing machine 100 and have a wide axial width. The pair of first tension rollers 471 press against the outside of both the upper-left belt 41 and the upper-right belt 42, thereby applying inward tension to each of the upper belts 41, 42. The pair of second tension rollers 472 are tension rollers that are rotatable about an axis that aligns with the left-right direction of the sewing machine 100 and have a narrow axial width. The pair of second tension rollers 472 press against only the upper-right belt 42 from the inside, thereby applying outward tension to the upper-right belt 42. The upper-right belt 42 is widened on both the front and rear sides by the pair of second tension rollers 472, thereby avoiding interference with the motor pulley 452, which is located along its path.

[0062] The upper link member 473 constituting the guide arm 475 has one end connected to the lower end of the motor bracket 451, and is rotatable at the connection site around an axis that extends in the left-right direction of the sewing machine 100. The other end of the link member 473 is connected to one end of the lower link member 474, and is rotatable at the connection site around an axis that extends in the left-right direction of the sewing machine 100. Furthermore, the other end of the lower link member 474 is connected to the front end of the mounting base 74, as described above, and is rotatable at the connection site around an axis that extends in the left-right direction of the sewing machine 100.

[0063] At the connection portion between the upper link member 473 and the lower link member 474, a guide roller 476 that abuts the inside of the loop from the front of the sewing machine 100 and a guide roller (not shown) that abuts the outside of the loop from the front of the sewing machine 100 are provided for the endless loop-shaped upper left belt 41 and upper right belt 42. As a result, the left and right upper belts 41, 42 are transported along a path along the upper link member 473 and a path along the lower link member 474. Therefore, even if the bending angles of the upper link member 473 and the lower link member 474 change due to changes in the thickness of the material to be sewn or the elevation of the presser foot 71 due to unevenness, the left and right upper belts 41, 42 maintain the path along the upper link member 473 and the path along the lower link member 474. As a result, the path length of each upper belt 41, 42 is maintained constant, and fluctuations in the tension of each upper belt 41, 42 can be suppressed.

[0064] [Positioning Ruler] In Figure 9, reference numeral 50 denotes a positioning ruler, and reference numeral 53 denotes its support mechanism. The positioning ruler 50 is used to position the side edge of the workpiece in the left-right direction when sewing while maintaining the side edge of the workpiece at a fixed distance (edge ​​width) from the needle drop position. The positioning ruler 50 has an abutment plate 51 against which the side edge of the workpiece on the needle plate 101 (the right edge in this embodiment) abuts, and a connecting portion 52 that connects the abutment plate 51 to the support mechanism 53. The abutment plate 51 is a flat plate that conforms to the front-to-rear and up-to-down planes of the upper feed mechanism 40, and the right edge of the workpiece abuts against the left surface to position the workpiece.

[0065] The support mechanism 53 has a holder shaft 54, a cylindrical body 55, an air cylinder, and a position adjustment motor 57 (see FIG. 11). The holder shaft 54 ​​holds the positioning ruler 50. The cylindrical body 55 holds the holder shaft 54 ​​with the holder shaft 54 ​​inserted therethrough. The air cylinder raises and lowers the positioning ruler 50 to switch between an in-use position on the needle plate 101 and a non-use position in which the positioning ruler 50 is retracted upward. The position adjustment motor 57 moves the positioning ruler 50 left and right via the holder shaft 54 ​​to perform positioning.

[0066] [Retraction Mechanism] Reference numeral 60 shown in Figures 8 to 10 denotes a retraction mechanism for maintaining the right-side belt guide 44 in the retracted position when the positioning ruler 50 is used. When the adjusted edge width is small, the abutment plate 51 is positioned close to the needle drop position. In this case, there is a risk that the rear end of the right-side belt guide 44 may interfere with the abutment plate 51, so the belt guide 44 is rotated around the support shaft to retract the rear end upward. The retraction mechanism 60 is a mechanism that holds the rear end of the belt guide 44 in a retracted position upward.

[0067] The retraction mechanism 60 includes a holding member 61 whose upper end is pivotally supported by the link member 474 via a support shaft 62 extending in the left-right direction. The holding member 61 has a recess 611 formed at its lower end, and an operating portion 612 for rotating the holding member 61 formed near the recess 611. By operating the operating portion 612 of the holding member 61 to rotate the holding member 61, the recess 611 of the holding member 61 can engage and hold the shaft portion 444 on the front end side that moves downward when the rear end of the belt guide 44 is retracted upward. This allows the holding member 61 of the retraction mechanism 60 to hold the rear end of the belt guide 44 in an upwardly retracted state. Reference numeral 63 denotes a torsion coil spring. The torsion coil spring 63 biases the holding member 61 in a direction that rotates the lower end of the holding member 61 forward. When the holding member 61 is not holding the belt guide 44 , the torsion coil spring 63 retracts the holding member 61 forward so that the lower end of the holding member 61 does not interfere with the belt guide 44 .

[0068] [Use of Sewing Machine] The sewing machine 100 configured as described above can perform sewing using upper belt feed and lower belt feed. In this case, the lower feed mechanism 20 can perform sewing using different feed speeds on the front and rear sides of the needle eye 13 by looping the lower belts 21-24 over in the manner shown in Fig. 6. In addition, the lower feed mechanism 20 can perform sewing using different feed speeds on the left and right sides of the needle eye 13 by looping the lower belts 21-24 over in the manner shown in Fig. 7.

[0069] On the other hand, when performing edge stitching along the right edge of the workpiece, the front end of the right belt guide 44 is pushed down to move it from the feed position to the retracted position, and the retracted position is maintained by the retraction mechanism 60. Then, the actuator of the support mechanism 53 of the positioning ruler 50 is driven to move the positioning ruler 50 from the non-use position to the use position. As a result, sewing is performed while feeding the workpiece so that the right edge of the workpiece always abuts against the left surface of the abutment plate 51 of the positioning ruler 50, thereby sewing with the desired edge stitch width.

[0070] [Sewing Machine Control System] Figure 11 is a block diagram showing the control system of the sewing machine 100. As shown in Figure 11, the sewing machine 100 is equipped with a control device 90 that controls the operation of each component. The sewing machine motor 16, the presser foot motor 73, the first motor 25, the second motor 26, the upper left motor 45, the upper right motor 46, and the position adjustment motor 57 are connected to the control device 90 via their respective motor drive circuits 16a, 73a, 25a, 26a, 45a, 46a, and 57a. The sewing machine motor 16, the presser foot motor 73, the first motor 25, the second motor 26, the upper left motor 45, the upper right motor 46, and the position adjustment motor 57 are also equipped with encoders 161, 732, 251, 261, 453, 461, and 571 that detect the number of rotations of the motors. These encoders 161, 732, 251, 261, 453, 461, and 571 are also connected to the control device 90 via motor drive circuits 16a, 73a, 25a, 26a, 45a, 46a, and 57a.

[0071] The control device 90 is also connected to an electromagnetic valve 58 via a drive circuit 58a, which operates a position switching air cylinder that switches the positioning ruler 50 between the use position and the non-use position.

[0072] The control device 90 includes a CPU 91, a ROM 92, a RAM 93, and a data memory 94, and executes various operational controls described below. The ROM 92 stores a system program that is the basis for operational control of the sewing machine 100. The data memory 94 stores various data and programs described below. The data memory 94 is made up of non-volatile semiconductor memory such as flash memory, EEPROM, or EPROM, but may also use storage such as an HDD. The CPU 91 executes the various programs in the ROM 92 and the data memory 94. The RAM 93 is a memory that serves as a work area for the CPU 91.

[0073] An operation input unit 96 serving as a setting input device is also connected to the control device 90 via an interface (I / F) 96a. The operation input unit 96 includes a display unit 961. The display unit 961 displays information required for inputting various settings. The display unit 961 is configured to include an input screen. The operation input unit 96 is configured as a so-called touch panel or touch screen in which a touch sensor is provided on the display unit 961 serving as the input screen. However, the display screen and the operation input unit may be configured as separate, independent units.

[0074] A pedal 95 is also connected to the control device 90 via an interface 95a. When the pedal 95 is depressed, it starts and stops sewing, increases or decreases the sewing speed, and inputs other commands. A height sensor 762 and left and right potentiometers 48 and 49 are also connected to the control device 90 via interfaces 762a, 48a, and 49a. The height sensor 762 detects the height of the presser foot 71.

[0075] [Control based on detection of the height of the feed position of the left and right upper belts] The control described below is suitable for sewing in which the lower belts 21 to 24 of the lower feed mechanism 20 are looped around in the manner shown in Figure 7 and the left and right sides of the needle hole 13 can be fed at different speeds.

[0076] The height sensor 762, which detects the height of the presser foot 71, and the left and right potentiometers 48, 49 detect the height of the workpiece at the feed position of the upper-left belt 41 and the height of the workpiece at the feed position of the upper-right belt 42, relative to the needle plate. In this way, the height sensor 762 and the left and right potentiometers 48, 49 function as detectors that detect the height relative to the needle plate. The left and right potentiometers 48, 49 also function as detectors that detect the height of the workpiece at the feed position of the upper-left belt 41 and the height of the workpiece at the feed position of the upper-right belt 42, relative to the presser foot. The left and right potentiometers 48, 49 also function as detectors that detect the difference in height between the workpiece at the feed position of the upper-left belt 41 and the workpiece at the feed position of the upper-right belt 42.

[0077] The "height of the workpiece at the feed position" refers to the height of the position where the left and right upper belts 41, 42 contact the workpiece near the rear ends of the left and right belt guides 43, 44. The belt guides 43, 44 are pressed against the workpiece at this position, so the height of the workpiece can be obtained by determining the height at this position.

[0078] Furthermore, the "height of the workpiece at the feed position" can also be said to be the height when viewed from the presser foot 71, which serves as a support member for supporting the left and right belt guides 43, 44. However, the "height of the workpiece at the feed positions of the left and right upper belts 41, 42" is not limited to the above example. For example, the "height of the workpiece at the feed position" may be the height from the top surface of the needle plate 101.

[0079] As described above, the left and right potentiometers 48, 49 detect the distance between the shafts 434, 444 located at the front ends of the belt guides 43, 44 and the shafts 745, 746 located diagonally above and rearward of the shafts 434, 444. There is a correlation between this distance and the height of the workpiece at the feed positions of the left and right upper belts 41, 42. Therefore, a height table 941 indicating this correlation is stored in the data memory 94. The CPU 91 of the control device 90 can obtain the "height of the workpiece at the feed positions of the left and right upper belts 41, 42" by referring to the detection values ​​of the potentiometers 48, 49 and the height table 941.

[0080] (1) The CPU 91 of the control device 90 can obtain the "height of the workpiece at the feed positions of the left and right upper belts 41, 42" from the detection values ​​of the potentiometers 48, 49. When using the sewing machine 100 of this example, the "height of the workpiece at the feed positions of the left and right upper belts 41, 42" in this case is defined as the "height based on the presser feet of the left and right upper belts 41, 42." (2) The CPU 91 can also obtain the "difference in height of the workpiece at the feed positions of the left and right upper belts 41, 42" from the difference in the amount of upward movement of the left and right belt guides 43, 44. (3) The CPU 91 can also obtain the height of the presser foot 71 from the top surface of the needle plate from the detection value of the height sensor 762. Therefore, by adding the "height of the workpiece at the feed positions of the left and right upper belts 41, 42" to the height of the presser foot 71 from the top surface of the needle plate, the CPU 91 can obtain the "height of the workpiece at the feed positions of the left and right upper belts 41, 42" as seen from the needle plate 101. When using the sewing machine 100 of this example, the "height of the workpiece at the feed position of the left and right upper belts 41, 42" in this case is defined as the "height of the left and right upper belts 41, 42 relative to the needle plate."

[0081] The left and right upper belts 41, 42 have individual set feed pitches, and the set feed pitch is intermittently fed for each stitch by controlling the operation of the left and right upper motors 45, 46. In response to this, the CPU 91 determines the value of one of (1) "the height of the left and right upper belts 41, 42 based on the presser foot," (2) "the difference in height of the workpiece at the feed positions of the left and right upper belts 41, 42," or (3) "the height of the left and right upper belts 41, 42 based on the needle plate," and executes operation control to correct the drive of the left and right upper motors 45, 46 based on the value.

[0082] When the CPU 91 acquires (1) the "height of the left and right upper belts 41, 42 relative to the presser foot," it controls the left and right upper motors 45, 46 as follows. If the upward movement of the feed position due to the rotation of the belt guides 43, 44 increases, the tension of the tension springs 433, 443 increases, and the pressure applied by the belt guides 43, 44 when they press against the belts increases. This increases the resistance to the conveyance of the left and right upper belts 41, 42. Therefore, the CPU 91 performs a correction to increase the feed speed or torque while maintaining the movement of the upper motors 45, 46 for one feed pitch. In this case, a feed table 942 is stored in the data memory 94, which defines the correspondence between the "height of the left and right upper belts 41, 42 relative to the presser foot" and the speed correction value or torque correction value of the upper motors 45, 46. The speed correction value and torque correction value may be, for example, a speed increase / decrease factor or a torque increase / decrease factor. Then, when the CPU 91 acquires the "height of the left and right upper belts 41, 42 based on the presser feet" for each of the left and right sides, it refers to the feed table 942 and performs operational control to individually correct the feed speed or torque for the left and right upper motors 45, 46 and drive them.

[0083] Furthermore, when the CPU 91 acquires (2) "the difference in height of the sewing material at the feed positions of the left and right upper belts 41, 42," the CPU 91 performs the following operational control on the left and right upper motors 45, 46. When the difference in height between the left and right upper belts 41, 42 increases between the left and right belt guides 43, 44, the tension of one of the tension springs 433, 443 increases, increasing the pressure when pressed by the corresponding belt guide 43, 44, and increasing the resistance to conveyance. Therefore, while maintaining the amount of movement for one feed pitch, the CPU 91 corrects the upper motor 45, 46 with the higher feed position by increasing the feed speed or the torque when driven, and corrects the upper motor 45, 46 with the lower feed position by decreasing the feed speed or the torque when driven. In this case, a feed table 942 that defines the correspondence between the difference in height between the feed positions and the increase / decrease in speed or torque of the upper motors 45, 46 is stored in the data memory 94. The speed increase / decrease value or torque increase / decrease value may be, for example, a speed increase / decrease multiplier value or a torque increase / decrease multiplier value. When the CPU 91 acquires the height difference between the feed positions of the upper belts 41, 42 of the left and right belt guides 43, 44, it references the feed table 942 and executes operation control to increase / decrease the speed or torque of the left and right upper motors 45, 46 to drive them. While the example of control in which one of the speeds or torques of the upper motors 45, 46 is increased and the other is decreased has been given, it is also possible to increase the speed or torque only for the upper belt 41, 42 whose feed position is higher, without making any correction for the upper motor whose feed position is lower.

[0084] When the CPU 91 acquires (3) the "height of the left and right upper belts 41, 42 relative to the needle plate," it controls the left and right upper motors 45, 46 as follows. The "height of the left and right upper belts 41, 42 relative to the needle plate" indicates the thickness of the sewing material. When the sewing material becomes thicker, the feed rate of the sewing material may decrease, depending on the material's material. For example, if the sewing material is flexible, the feed rate may decrease. Therefore, when the sewing material becomes thicker, a correction is made by adding a feed rate to the feed pitch set for the upper motor 45 or 46. In this case, a feed table 942 is stored in the data memory 94. The feed rate table 942 defines the correspondence between the "height of the left and right upper belts 41, 42 relative to the needle plate" and the additional feed rate of the upper motors 45, 46. The additional feed rate may be, for example, a feed rate increase factor. Then, when the CPU 91 acquires the "height of the left and right upper belts 41, 42 relative to the needle plate" for the left and right belt guides 43, 44, it refers to the feed table 942 and executes operational control to correct the set feed pitch and drive the left and right upper motors 45, 46, respectively.

[0085] The sewing machine 100 may be configured to acquire only one of (1) "the height of the left and right upper belts 41, 42 based on the presser foot," (2) "the difference in height of the workpiece at the feed position of the left and right upper belts 41, 42," or (3) "the height of the left and right upper belts 41, 42 based on the needle plate," and to control only the operation of the left and right upper motors 45, 46 corresponding to the acquired information. Alternatively, the sewing machine 100 may acquire the information (1) to (3), but only control the operation of the corresponding information selected by the operation input unit 96. In this case, the operation input unit 96 functions as a selection setting unit. Furthermore, the sewing machine 100 may acquire two or more of the information (1) to (3), and to control all the operation of the corresponding left and right upper motors 45, 46.

[0086] Furthermore, (1) when the "height of the left and right upper belts 41, 42 relative to the presser feet of the left and right upper belts 41, 42" is acquired, the left and right upper motors 45, 46 are corrected to increase the feed speed or the torque during drive. However, instead of or in parallel with these, operational control may be performed to correct and drive the motors so as to increase the set feed pitch. In this case, a feed table that defines the correspondence relationship between the "height of the left and right upper belts 41, 42 relative to the presser feet" and the additional value of the feed amount of the upper motors 45, 46 may be stored in the data memory 94. In this case, the additional value of the feed amount may also be, for example, a value representing an increase magnification of the feed amount.

[0087] In addition, (2) when the "difference in height of the sewing workpiece at the feed positions of the left and right upper belts 41, 42" is acquired, the left and right upper motors 45, 46 are corrected to increase the feed speed or the torque during driving. However, instead of or in parallel with these, operational control may be executed to correct and drive the motors 45, 46 to increase the set feed pitch. In this case, a feed table that defines the correspondence relationship between the "difference in height of the sewing workpiece at the feed positions of the left and right upper belts 41, 42" and the additional value of the feed amount of the upper motors 45, 46 may be stored in the data memory 94. In this case, the additional value of the feed amount may also be, for example, a value of an increase magnification of the feed amount.

[0088] Furthermore, (3) when the "height of the left and right upper belts 41, 42 relative to the needle plate" as viewed from the needle plate 101 is obtained, the left and right upper motors 45, 46 are controlled to increase their set feed pitches. However, instead of or in parallel with this, a correction to increase the feed speed or a correction to increase the torque during driving may be performed. In this case, a feed table defining the correspondence between the "height of the left and right upper belts 41, 42 relative to the needle plate" and the speed correction value or torque correction value of the upper motors 45, 46 may be stored in the data memory 94. In this case, the speed correction value may also be a speed increase / decrease factor. Furthermore, the torque correction value may also be a torque increase factor.

[0089] In either case, various tables used to correct the driving of the left and right upper motors 45, 46 in response to the acquisition of the above (1) to (3) may be created by input from the operation input unit 96. In this case, the operation input unit 96 functions as a numerical value setting unit.

[0090] Furthermore, when the CPU 91 obtains (1) the "heights of the left and right upper belts 41, 42 relative to the presser foot," (2) the "difference in height of the workpiece at the feed positions of the left and right upper belts 41, 42," and (3) the "heights of the left and right upper belts 41, 42 relative to the needle plate," the CPU 91 performs a correction to increase the feed speed, the torque during drive, or the feed amount for the upper left motor 45 or the upper right motor 46 that drives the upper left belt 41 or the upper right belt 42 that has a higher feed position. However, the corrections of the present disclosure are not limited to the above examples. For example, depending on the type of workpiece and the support structure of the upper belts 41, 42, the CPU 91 may perform a correction to increase the feed speed, the torque during drive, or the feed amount for the upper left motor 45 or the upper right motor 46 that drives the upper left belt 41 or the upper right belt 42 that has a lower feed position. In these cases, it is desirable to store various necessary tables in the data memory 94. In addition, the sewing machine 100 may be configured to be able to select whether to perform a correction to increase the feed speed, a correction to increase the torque during driving, or a correction to add the feed amount when the height of the feed position is high or low.

[0091] [Technical Effects of the Embodiments of the Present Disclosure] The sewing machine 100 includes, as detection units, left and right potentiometers 48, 49 and a height sensor 762, and based on the detection by these detection units, the control device 90 controls the adjustment of the driving of the feed of the conveyor belts 41, 42 by the left and right upper motors 45, 46 of the upper feed mechanism 40. As a result, when there is a difference in thickness of the sewn material on the left and right sides of the needle drop position, the conveying operation by the upper feed mechanism 40 can be adjusted, and the sewn material can be fed appropriately.

[0092] The control device 90 also controls the adjustment of the feed amount (feed pitch) of one or both of the upper left belt 41 and the upper right belt 42 based on the detection by the above-mentioned detector. This makes it possible to suppress any fluctuations in the feed amount between the left and right belts due to differences in height. In particular, the control device 90 controls the feed amount of one of the left and right upper belts 41, 42, which has a higher height of the sewn material at the feed position, thereby suppressing a reduction in the feed amount that may occur due to an increase in the thickness of the sewn material. Furthermore, the control device 90 controls the feed amount of one of the left and right upper belts 41, 42, which has a lower height of the sewn material at the feed position, thereby suppressing a reduction in the feed amount that may occur due to a decrease in the thickness of the sewn material, which may occur depending on the type of sewn material.

[0093] The control device 90 also controls the feed speed of one or both of the left upper belt 41 and the right upper belt 42 based on the detection by the above-mentioned detector. This makes it possible to suppress fluctuations in the feed speeds between the left and right belts due to differences in height. In particular, the control device 90 controls the feed speed of the left or right upper belt 41, 42, whichever belt has a higher height of the sewn material at the feed position, to increase the speed, thereby suppressing a decrease in the feed speed that may occur due to an increase in the thickness of the sewn material. Furthermore, the control device 90 controls the feed speed of the left or right upper belt 41, 42, whichever belt has a lower height of the sewn material at the feed position, to increase the speed, thereby suppressing a decrease in the feed speed that may occur due to a decrease in the thickness of the sewn material, which may occur depending on the type of sewn material.

[0094] Furthermore, the control device 90 controls the torque of one or both of the motor that feeds the left upper belt 41 and the left and right upper motors 45, 46 that feed the right upper belt 42 based on the detection by the above-mentioned detector. This makes it possible to suppress fluctuations in the left and right feed torque due to differences in height. In particular, the control device 90 controls the torque of the upper motor 45 or 46 that feeds the upper belt 41, 42 that is higher in height at the feed position of the left and right upper belts 41, 42, thereby suppressing a reduction in feed torque that may occur due to an increase in the thickness of the sewn material. Furthermore, the control device 90 controls the torque of the upper motor 45 or 46 that feeds the upper belt 41, 42 that is lower in height at the feed position of the left and right upper belts 41, 42, thereby suppressing a reduction in feed torque that may occur due to a decrease in the thickness of the sewn material, which may occur depending on the type of sewn material.

[0095] [Others] The above describes the embodiments of the present disclosure. However, the present disclosure is not limited to the above embodiments. For example, in the embodiments, a component integrally formed from a single member may be replaced with a component divided into multiple members that are connected or fixed to each other. Furthermore, a component formed by connecting multiple members may be replaced with a component integrally formed from a single member. In addition, the details shown in the embodiments may be modified as appropriate without departing from the spirit of the invention.

[0096] For example, the feed position detected by the detection unit is not limited to the position where the upper belts 41, 42 abut on the left and right belt guides 43, 44, but also includes the surrounding area, for example, near the upstream or downstream side of the abutting position, in which there is no significant difference in the detected values ​​(a range that can be considered to be substantially the same).

[0097] Furthermore, the detectors for detecting the height of the workpiece at the feed positions of the left and right upper belts 41, 42 are not limited to the above configuration, and any detector capable of detecting the height of the workpiece at the feed positions may be used. For example, as shown in FIG. 12, optical distance sensors 48A, 49A may be used. In this case, it is preferable that the distance sensors 48A, 49A detect the distance from above, immediately upstream of the position on the workpiece where the left and right upper belts 41, 42 contact each other. It is preferable that the distance sensors 48A, 49A be provided in a position where the height does not change during sewing, such as above the detection position and below the sewing machine arm 113. In this case, each distance sensor 48A, 49A can independently detect the "height of the workpiece relative to the needle plate at the feed positions of the left and right upper belts 41, 42" as viewed from the needle plate 101, thereby obtaining the thickness of the workpiece at each detection position.

[0098] Furthermore, a linear sensor or a magnetic sensor that detects the center distance may be used as the detection unit instead of the potentiometers 48 and 49 that detect the center distance between the left and right belt guides 43 and 44. Furthermore, a rotary potentiometer or encoder that detects the angle of the left and right belt guides 43 and 44 around the support shaft 431 may be used as the detection unit.

[0099] In addition, in the above-described sewing machine 100, as shown in Fig. 4, the needle hole 13 is provided in the needle hole member 30 that moves up and down relative to the needle plate 101 at the same cycle as the sewing needle 11, but the present invention is not limited to this. For example, as shown in Fig. 13, the needle hole 13 may be formed by directly penetrating the needle plate 101, and the needle hole 13 may be fixedly provided in a member that does not move up and down.

[0100] The present disclosure includes the following aspects. Clause 1: A sewing machine comprising: a needle up-and-down movement mechanism that moves a sewing needle up and down using a sewing machine motor; an upper feed mechanism that feeds a workpiece on a needle plate by bringing a conveyor belt into contact with the left and right sides of a needle drop position from above, respectively; a detection unit that detects the height of the workpiece at the feed position of the left conveyor belt and the height of the workpiece at the feed position of the right conveyor belt, or detects the difference therebetween; and a control device that controls the operation of the needle up-and-down movement mechanism and the upper feed mechanism, wherein the control device controls to adjust the drive of the feed of the left and right conveyor belts of the upper feed mechanism based on detection by the detection unit. Clause 2: The sewing machine according to Clause 1, wherein the control device controls to adjust the feed amount of one or both of the left and right conveyor belts based on detection by the detection unit. Clause 3: The sewing machine according to Clause 1 or Clause 2, wherein the control device controls to relatively increase the feed amount of the left or right conveyor belt that has the higher height of the workpiece at the feed position. Clause 4 The sewing machine according to Clause 1 or Clause 2, wherein the control device performs control to relatively increase the feed rate of one of the left and right conveyor belts which has a lower height of the sewn workpiece at the feed position. Clause 5 The sewing machine according to any one of Clauses 1 to 4, wherein the control device performs control to adjust the feed speed of one or both of the left and right conveyor belts based on detection by the detection unit. Clause 6 The sewing machine according to any one of Clauses 1 to 5, wherein the control device performs control to relatively increase the feed speed of one of the left and right conveyor belts which has a higher height of the sewn workpiece at the feed position. Clause 7 The sewing machine according to any one of Clauses 1 to 5, wherein the control device performs control to relatively increase the feed speed of one of the left and right conveyor belts which has a lower height of the sewn workpiece at the feed position. Clause 8 The sewing machine according to any one of Clauses 1 to 7, wherein the control device performs control to relatively increase the torque of one or both of the motor which feeds the left conveyor belt and the motor which feeds the right conveyor belt based on detection by the detection unit.Clause 9: The sewing machine according to any one of clauses 1 to 8, wherein the control device performs control to relatively increase the torque of a motor that feeds one of the left and right conveyor belts, which has a higher height of the sewn workpiece at the feed position. Clause 10: The sewing machine according to any one of clauses 1 to 8, wherein the control device performs control to relatively increase the torque of a motor that feeds one of the left and right conveyor belts, which has a lower height of the sewn workpiece at the feed position. Clause 11: The sewing machine according to any one of clauses 1 to 10, wherein the detection unit is capable of detecting a height based on a presser foot and a height based on a needle plate as the height of the sewn workpiece at the feed position of the left conveyor belt and the height of the sewn workpiece at the feed position of the right conveyor belt, and the control device includes a selection setting unit that selects whether to adjust the drive of the feed of the left and right conveyor belts of the upper feed mechanism based on the difference between the height based on the presser foot and the height based on the needle plate. Clause 12: The sewing machine according to any one of clauses 1 to 11, wherein the control device includes a value setting unit that sets a value to be adjusted.

[0101] This application is based on Japanese Patent Application No. 2023-152063, filed on September 20, 2023, the contents of which are incorporated herein by reference.

Claims

1. A sewing machine comprising: a needle up and down movement mechanism which moves the sewing needle up and down using a sewing machine motor; an upper feed mechanism which feeds the workpiece on the needle plate by contacting a conveyor belt from above on both the left and right sides of the needle drop position; a detection unit for detecting the height of the workpiece at the feed position of the conveyor belt on the left side and the height of the workpiece at the feed position of the conveyor belt on the right side or detecting the difference between them; and a control device which controls the operation of the needle up and down movement mechanism and the upper feed mechanism, wherein the control device controls the adjustment of the drive of the feed of the conveyor belt on the left and right sides of the upper feed mechanism based on the detection by the detection unit.

2. The sewing machine according to claim 1, wherein the control device performs control to adjust the feed rate of one or both of the left and right conveyor belts based on detection by the detection unit.

3. The sewing machine according to claim 2, wherein the control device performs control to relatively increase the feed rate of one of the left and right conveyor belts which has a higher height of the sewing workpiece at the feed position.

4. The sewing machine according to claim 2, wherein the control device performs control to relatively increase the feed amount of one of the left and right conveyor belts which has a lower height of the sewing workpiece at the feed position.

5. The sewing machine according to claim 1, wherein the control device performs control to adjust the feed speed of one or both of the left and right conveyor belts based on detection by the detection unit.

6. The sewing machine according to claim 5, wherein said control device controls the feed speed of one of said right and left conveyor belts, the one having the higher height of the sewing workpiece at the feed position, to be relatively faster.

7. The sewing machine according to claim 5, wherein the control device controls the feed speed of one of the left and right conveyor belts, which has a lower height of the sewing workpiece at the feed position, to be relatively faster.

8. The sewing machine according to claim 1, wherein the control device performs control to adjust the torque of one or both of the motor that feeds the left side conveyor belt and the motor that feeds the right side conveyor belt based on detection by the detection unit.

9. The sewing machine according to claim 8, wherein the control device performs control so as to relatively increase the torque of the motor which feeds the one of the left and right conveyor belts which has a higher height of the sewing workpiece at the feed position.

10. The sewing machine according to claim 8, wherein the control device performs control so as to relatively increase the torque of the motor which feeds the one of the left and right conveyor belts which has a lower height of the sewing workpiece at the feed position.

11. A sewing machine as described in any one of claims 1 to 10, wherein the detection unit is capable of detecting the height of the sewn workpiece at the feed position of the left conveyor belt and the height of the sewn workpiece at the feed position of the right conveyor belt, the height being based on the presser foot and the height being based on the needle plate, and the control device is provided with a selection setting unit which selects whether to adjust the feed drive of the conveyor belts on the left and right of the upper feed mechanism based on either the height based on the presser foot or the height based on the needle plate, or the difference between the heights.

12. The sewing machine according to claim 2, claim 5 or claim 8, wherein the control device is provided with a numerical value setting section for setting a numerical value to be adjusted.

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