Sewing machine

Abstract

A sewing machine (100) includes feed mechanisms (20 and 40) that feed workpieces (C1 and C2) on a throat plate (101) in a stitch direction, and an end portion detection device (80) that detects end portions of the workpieces (C1 and C2) in a direction orthogonal to the stitch direction. The feed mechanisms (20 and 40) enables differential feed, creating a variance in feed amount in the stitch direction between the left and right sides of the stitch point position. The sewing machine (100) includes a control device (90) that controls the difference in feed amount in the stitch direction between the left and right sides by the feed mechanisms (20 and 40), based on detection by the end portion detection device (80).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a sewing machine that performs left-and-right differential feed.BACKGROUND ART

[0002] A sewing machine of the related art performs sewing while moving a workpiece on a throat plate, which is fed in a stitch direction by feeding dots, by a roller mechanism that feeds the workpiece in a direction orthogonal to a feed direction by the feeding dots, thereby aligning a position of a side end portion of the workpiece to a proper position (see, for example, Patent Literature 1).CITATION LISTPATENT LITERATURE

[0003] Patent Literature 1: JP2013-059577ASUMMARY OF INVENTIONTECHNICAL PROBLEM

[0004] In the configuration of the above-described sewing machine of the related art, since the roller mechanism is configured to perform feed in the direction orthogonal to the feed direction by the feeding dots, there is a risk that feed by the feeding dots will be affected.

[0005] An object of the present disclosure is to smoothly feed a workpiece while aligning a side end portion of the workpiece to a proper position.SOLUTION TO PROBLEM

[0006] The present disclosure provides a sewing machine including: a feed mechanism configured to feed a workpiece on a throat plate in a stitch direction; and an end portion detection device configured to detect an end portion of the workpiece in a direction orthogonal to the stitch direction, in which the feed mechanism enables differential feed, creating a variance in feed amount in the stitch direction between the left and right sides of the stitch point position, and the sewing machine includes a control device configured to control the difference in feed amount in the stitch direction between the left and right sides by the feed mechanism, based on detection by the end portion detection device. ADVANTAGEOUS EFFECTS OF INVENTION

[0007] The sewing machine of the present disclosure allows smooth feed of a workpiece while aligning a side end portion of the workpiece to a proper position.BRIEF DESCRIPTION OF DRAWINGS

[0008] [FIG. 1] FIG. 1 is a rear view of a sewing machine according to an embodiment of the present disclosure. [FIG. 2] FIG. 2 is a left side view of the sewing machine. [FIG. 3] FIG. 3 is a perspective view of the sewing machine. [FIG. 4] FIG. 4 is a perspective view showing an upper surface of a left end portion of a sewing machine bed portion (a presser foot is not shown). [FIG. 5] FIG. 5 is a perspective view of a guide frame of a lower feed mechanism. [FIG. 6] FIG. 6 is a perspective view of a feed mechanism in which four conveyor belts are in a front-and-rear differential feed state. [FIG. 7] FIG. 7 is a perspective view of the feed mechanism in which the four conveyor belts are in a left-and-right differential feed state. [FIG. 8] FIG. 8 is a perspective view of a cloth presser mechanism that presses a workpiece on a throat plate from above. [FIG. 9] FIG. 9 is a rear view of the cloth presser mechanism. [FIG. 10] FIG. 10 is an exploded perspective view of the cloth presser mechanism. [FIG. 11] FIG. 11 is a perspective view showing the periphery of a throat plate provided with an end portion detection device. [FIG. 12] FIG. 12 is a rear view showing the periphery of the throat plate provided with the end portion detection device. [FIG. 13] FIG. 13 is a block diagram showing a control system of the sewing machine. [FIG. 14] FIG. 14 is a flowchart showing sewing operation control that is executed by a control device. [FIG. 15] FIG. 15 is a rear view of a sensor holding frame, which is another form of the end portion detection device. [FIG. 16] FIG. 16 is a perspective view of a sewing machine having a plurality of air outlets provided in an upper surface of a sewing machine bed portion. DESCRIPTION OF EMBODIMENTS[Schematic Configuration of Embodiment]

[0009] Hereinafter, a sewing machine, which is an embodiment of the present disclosure, will be described in detail.

[0010] FIG. 1 shows a rear view of a sewing machine 100, FIG. 2 shows a left side view of the sewing machine 100, and FIG. 3 shows a perspective view of the sewing machine 100.

[0011] Hereinafter, the downstream side of the feed direction of the workpiece is referred to as "front", the upstream side of the feed direction is referred to as "rear", the left side when facing forward is referred to as "left", the right side is referred to as "right", the vertically upward direction is referred to as "up", and the vertically downward direction is referred to as "down". The front-and-rear, left-and-right, and up-and-down directions are orthogonal to each other.

[0012] In the following description, it is assumed that the sewing machine 100 is installed on a horizontal plane, and the front-and-rear and left-and-right directions are horizontal.

[0013] As the sewing machine 100, which is an embodiment of the present disclosure, a lockstitch sewing machine having a function of differential feed is exemplified.

[0014] The sewing machine 100 includes a needle up-and-down movement mechanism, a lower feed mechanism 20 as a feed mechanism, an upper feed mechanism 40 as a feed mechanism, a cloth presser mechanism 70 as a presser mechanism, a shuttle mechanism, an end portion detection device 80, and a control device 90. The end portion detection device 80 is shown in FIG. 11, and is not shown in FIGS. 1 to 10.

[0015] The needle up-and-down movement mechanism applies an up-and-down movement to a stitch needle 11.

[0016] The lower feed mechanism 20 applies a feed operation from below to a workpiece on a throat plate 101.

[0017] The upper feed mechanism 40 applies a feed operation from above to the workpiece on the throat plate 101.

[0018] The cloth presser mechanism 70 applies pressing pressure to the workpiece on the throat plate 101.

[0019] The shuttle mechanism captures a loop of upper thread from the stitch needle 11 and entwines it with a lower thread, thereby forming a seam.

[0020] The end portion detection device 80 detects positions, in the left-and-right direction on the throat plate 101, of respective side end portions (right end portions) of an upper cloth C1 (see FIG. 12) as an upper workpiece and a lower cloth C2 (see FIG. 12) as a lower workpiece.

[0021] The control device 90 executes operation control of each of the above components.

[0022] Note that the sewing machine 100 includes various components such as a thread take-up lever mechanism and a thread tensioner, which are included in general lockstitch sewing machines. However, the descriptions thereof are omitted as they are well-known in the art.[Sewing Machine Frame]

[0023] The sewing machine frame 110 supports or houses each component of the sewing machine 100 described above.

[0024] The sewing machine frame 110 includes a sewing machine bed portion 111, an upright drum portion 112, and a sewing machine arm portion 113.

[0025] The sewing machine bed portion 111 is located at a lower portion of the sewing machine 100 and extends in the left-and-right direction.

[0026] The upright drum portion 112 is erected from a right end portion of the sewing machine bed portion 111.

[0027] The sewing arm portion 113 extends leftward from an upper end portion of the upright drum portion 112.[Needle Up-and-Down Movement Mechanism]

[0028] FIG. 4 is a perspective view showing an upper surface of a left end portion of the sewing machine bed portion 111. In FIG. 4, a presser foot described below is omitted.

[0029] As shown in FIGS. 1 to 4, the needle up-and-down movement mechanism includes an upper shaft that is arranged inside the sewing machine arm portion 113, is rotationally driven by a sewing machine motor, and extends in the left-and-right direction.

[0030] In addition, the needle up-and-down movement mechanism includes a needle bar 12 that holds the stitch needle 11 at a lower end portion, and a crank mechanism that converts rotational force of the upper shaft into a reciprocating drive force for up-and-down movement and transmits the force to the needle bar.

[0031] Note that illustrations of the upper shaft and the crank mechanism are omitted because they are well known in the art.

[0032] The needle bar 12 extends in the up-and-down direction and is supported at a lower left end portion of the sewing machine arm portion 113 so as to be movable up and down.

[0033] The stitch needle 11 is held at a lower end portion of the needle bar 12 and moves up and down together with the needle bar 12. Below the needle bar 12 on an upper surface of the sewing machine bed portion 111, a throat plate 101 made of a horizontal flat plate is provided.

[0034] A combined opening portion 102 is formed at a stitch point position of the stitch needle 11 with respect to the throat plate 101. In the combined opening portion 102 of the throat plate 101, an eye member 30 having an eye 13, a rear left lower belt 21 and a front left lower belt 22 as left belts of the lower feed mechanism 20 described below, and a front right lower belt 23 and a rear right lower belt 24 as right belts are arranged to be exposed upward. That is, the combined opening portion 102 has a shape in which a plurality of rectangular opening portions through which the eye member 30 and each of the lower belts 21 to 24 are exposed are integrally combined.[Shuttle Mechanism]

[0035] As shown in FIGS. 2 and 3, the shuttle mechanism includes an outer shuttle 14 and an inner shuttle 15 provided on a lower side of the eye member 30 of the throat plate 101, and a shuttle shaft (not shown) for rotating the inner shuttle 15.

[0036] The shuttle shaft is rotatably supported within the sewing machine bed portion 111, while extending in the left-and-right direction. Rotation about an axis extending in the left-and-right direction, which is transmitted from the upper shaft and increased to a speed twice that of the upper shaft via a gear mechanism or a belt mechanism, is input to the shuttle shaft.

[0037] The inner shuttle 15 is housed inside the outer shuttle 14. Additionally, the inner shuttle 15 houses a bobbin (not shown) that supplies a lower thread inside the inner shuttle.

[0038] The outer shuttle 14 is connected to a left end portion of the shuttle shaft and rotates around the inner shuttle. The inner shuttle 15 is restricted from rotating so as not to rotate together with the outer shuttle 14. The outer shuttle 14 has a hook for capturing a loop of upper thread from the stitch needle 11 at an outer periphery thereof. By rotating, the outer shuttle 14 is capable of capturing a loop of upper thread with its hook and passing the loop under a lower thread reeled out from inside the inner shuttle 15.

[0039] The outer shuttle 14 and the inner shuttle 15 are arranged in a housed state inside a substantially cylindrical guide frame 29 of the lower feed mechanism 20 described below.[Lower Feed Mechanism]

[0040] FIG. 5 is a perspective view of the guide frame 29 of the lower feed mechanism 20, and FIGS. 6 and 7 are perspective views of the lower feed mechanism 20. FIGS. 6 and 7 show different wrapping states of the respective lower belts 21 to 24 described below.

[0041] Below, the lower feed mechanism 20 will be described in detail based on FIGS. 1 to 7.

[0042] As shown in each drawing, the lower feed mechanism 20 includes each of lower belts 21 to 24 as conveyor belts, a first motor 25, a second motor 26, rotation shafts 27 and 28, a first pulley 31, and a second pulley 32.

[0043] In addition, the lower feed mechanism 20 includes a guide frame 29 that guides each of the lower belts 21 to 24 to come into contact with a lower surface of a workpiece, a first pressurizing mechanism 33, and a second pressurizing mechanism 34.

[0044] Both the first motor 25 and the second motor 26 are motors whose operation amount can be arbitrarily controlled. The first motor 25 and the second motor 26 are, for example, DC motors, AC motors, stepping motors, or the like. The first motor 25 and the second motor 26 are arranged inside a right end portion of the sewing machine bed portion 111 in a state of being aligned in the front-and-rear direction, with output shafts oriented leftward.

[0045] The first pulley 31 is connected to the output shaft of the front-side first motor 25 via the rotation shaft 27.

[0046] The second pulley 32 is connected to the output shaft of the rear-side second motor 26 via the rotation shaft 28.

[0047] Both the rotation shafts 27 and 28 are parallel in the left-and-right direction and are rotatably supported within the sewing machine bed portion 111.

[0048] The first pulley 31 and the second pulley 32 are rotatably supported about axes extending in the left-and-right directions within a left end portion of the sewing machine bed portion 111. The first pulley 31 and the second pulley 32 are rotationally driven by the first motor 25 and the second motor 26 via the rotation shafts 27 and 28, respectively.

[0049] The first pulley 31 and the second pulley 32 are arranged in an overlapping manner when viewed from the front-and-rear direction, i.e., are positioned at the same height and at the same location in the left-and-right direction. Additionally, the first pulley 31 is arranged forward of the second pulley 32.

[0050] Both the first pulley 31 and the second pulley 32 can be wrapped with all of the lower belts 21, 22, 23, and 24, which are arranged in parallel in the left-and-right direction.

[0051] That is, the first pulley 31 has, on its outer peripheral surface, a left groove 311 for wrapping the rear left lower belt 21 and the front left lower belt 22, and a right groove 312 for wrapping the front right lower belt 23 and the rear right lower belt 24.

[0052] The second pulley 32 has, on its outer peripheral surface, a left groove 321 for wrapping the rear left lower belt 21 and the front left lower belt 22, and a right groove 322 for wrapping the front right lower belt 23 and the rear right lower belt 24.

[0053] Each of the lower belts 21 to 24 has the same width, and the left grooves 311 and 321 and the right grooves 312 and 322 all have a width corresponding to at least two belts.

[0054] Accordingly, each of the lower belts 21 to 24 can be selectively wrapped around the first pulley 31 or the second pulley 32.

[0055] Each of the lower belts 21, 22, 23 and 24 has an endless loop shape and is wrapped between the guide frame 29 and the first pulley 31 or between the guide frame 29 and the second pulley 32.

[0056] In addition, the respective lower belts 21, 22, 23, and 24 are arranged in parallel in the order from left to right.

[0057] As shown in FIG. 2, the guide frame 29 (guide member) is arranged so as to substantially coincide with the first pulley 31 and the second pulley 32 in the left-and-right direction and to be located between the first pulley 31 and the second pulley 32 in the front-and-rear direction. Additionally, the guide frame 29 is arranged above the first pulley 31 and the second pulley 32, and directly below the throat plate 101.

[0058] As shown in FIG. 5, the guide frame 29 includes a bracket portion 295 for fixing the guide frame 29 within the sewing machine bed portion 111, and a cylindrical main body portion 296 for guiding each of the lower belts 21 to 24.

[0059] The guide frame 29 is arranged directly below the throat plate 101 with a central axis of the main body portion 296 oriented in the left-and-right direction.

[0060] A fitting groove 297 extending in the front-and-rear direction is formed at a center, in the left-and-right direction, of an upper portion of an outer peripheral surface of the main body portion 296. The plate-shaped eye member 30, which is elongated in the front-and-rear direction, is fixedly fitted and arranged inside the fitting groove 297. The eye member 30 is formed with an eye 13 penetrating in the up-and-down direction at a stitch point position.

[0061] A surface of the eye member 30 where the eye 13 is formed is flush with or slightly higher than an upper surface of the throat plate 101.

[0062] In addition, the main body portion 296 allows each of the lower belts 21 to 24 to circumferentially slide on the upper portion of the outer peripheral surface of the main body portion 296, thereby feeding a workpiece. To this end, a first guide portion 291, a second guide portion 292, a third guide portion 293, and a fourth guide portion 294 are provided on the upper portion of the outer peripheral surface of the main body portion 296 to respectively guide the lower belts 21 to 24.

[0063] The first guide portion 291 is provided at the left rear of the eye 13, the second guide portion 292 is provided at the left front of the eye 13, the third guide portion 293 is provided at the right front of the eye 13, and the fourth guide portion 294 is provided at the right rear of the eye 13.

[0064] Each of the guide portions 291 to 294 is a projection extending in the front-and-rear direction, and has a width in the left-and-right direction equal to or slightly greater than a width of each of the lower belts 21 to 24. A rear end portion of each of the guide portions 291 to 294 forms a slope in which an amount of protrusion radially outward from the outer peripheral surface of the main body portion 296 gradually increases toward the front. In addition, a front end portion of each of the guide portions 291 to 294 forms a slope in which an amount of protrusion radially outward from the outer peripheral surface of the main body portion 296 gradually decreases toward the front.

[0065] The first guide portion 291 is located to the left of the eye 13 and rearward of the center of the eye 13 over almost its entire length.

[0066] The first guide portion 291 has a guide surface 291a (a portion indicated by dots in FIG. 5) that is flat and horizontal forward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 291a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0067] The guide surface 291a is set such that an outer surface of the rear left lower belt 21, which passes in sliding contact on the guide surface 291a, is slightly higher than the upper surface of the throat plate 101.

[0068] The guide surface 291a is formed such that a front end portion of the guide surface 291a is located slightly rearward of the center of the eye 13, and the rear left lower belt 21 comes into contact with a workpiece rearward of the center of the eye 13.

[0069] The second guide portion 292 is located to the left of the eye 13, to the right of the first guide portion 291 and forward of the center of the eye 13 over almost its entire length.

[0070] The second guide portion 292 has a guide surface 292a (a portion indicated by dots in FIG. 5) that is flat and horizontal rearward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 292a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0071] The guide surface 292a is set such that an outer surface of the front left lower belt 22, which passes in sliding contact on the guide surface 292a, is slightly higher than the upper surface of the throat plate 101.

[0072] The guide surface 292a is formed such that a rear end portion of the guide surface 292a is located slightly forward of the center of the eye 13, and the front left lower belt 22 comes into contact with a workpiece forward of the center of the eye 13.

[0073] The third guide portion 293 is located to the right of the eye 13 and forward of the center of the eye 13 over almost its entire length.

[0074] The third guide portion 293 has a guide surface 293a (a portion indicated by dots in FIG. 5) that is flat and horizontal rearward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 293a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0075] The guide surface 293a is set such that an outer surface of the front right lower belt 23, which passes in sliding contact on the guide surface 293a, is slightly higher than the upper surface of the throat plate 101.

[0076] The guide surface 293a is formed such that a rear end portion of the guide surface 293a is located slightly forward of the center of the eye 13, and the front right lower belt 23 comes into contact with a workpiece forward of the center of the eye 13.

[0077] The fourth guide portion 294 is located to the right of the eye 13 and the third guide portion 293 and rearward of the center of the eye 13 over almost its entire length.

[0078] The fourth guide portion 294 has a guide surface 294a (a portion indicated by dots in FIG. 5) that is flat and horizontal forward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 294a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0079] The guide surface 294a is set such that an outer surface of the rear right lower belt 24, which passes in sliding contact on the guide surface 294a, is slightly higher than the upper surface of the throat plate 101.

[0080] The guide surface 294a is formed such that a front end portion of the guide surface 294a is located slightly rearward of the center of the eye 13, and the rear right lower belt 24 comes into contact with a workpiece rearward of the center of the eye 13.

[0081] The guide surfaces 291a and 294a are provided rearward of the center of the eye 13, and the guide surfaces 292a and 293a are provided forward of the center of the eye 13. For this reason, when a speed difference (difference in conveying amount) 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 respective lower belts 21 to 24 can apply a conveying force caused by the front-and-rear feed speed difference (difference in conveying amount) to the workpiece without interfering with each other. Accordingly, a seam as intended is formed during differential feed in the front-and-rear direction, making it possible to improve stitch quality.

[0082] The first pressurizing mechanism 33 applies tension to all of the belts, among the lower belts 21 to 24, wrapped between the guide frame 29 and the first pulley 31, thereby suppressing sagging.

[0083] The first pressurizing mechanism 33 includes a left pressurizing roller 331, a right pressurizing roller 332, a support plate 333, and a base block 334, as shown in FIGS. 2, 3, and 6.

[0084] The support plate 333 has an elongated flat plate shape extending in the front-and-rear and up-and-down directions, and is supported by the base block 334 with its longitudinal direction oriented obliquely upward and forward.

[0085] Additionally, the support plate 333 concentrically and rotatably supports the left pressurizing roller 331 and the right pressurizing roller 332 on left and right surfaces of an upper end portion of the support plate 333. The support plate 333 is arranged such that the left pressurizing roller 331 and the right pressurizing roller 332 come into contact with the outer surface of the belt extending between the guide frame 29 and the first pulley 31 from a lower rear side.

[0086] The base block 334 is shared with the second pressurizing mechanism 34 described below, and supports the structures of the first pressurizing mechanism 33 and the second pressurizing mechanism 34. The base block 334 is fixedly provided below the guide frame 29 within the sewing machine bed portion 111.

[0087] The support plate 333 has an elongated hole extending in the longitudinal direction of the support plate 333, and is fastened and fixed to the base block 334 by two bolts inserted into the elongated hole. The longitudinal direction of the support plate 333 is oriented in a direction approximately orthogonal to the belt that is wrapped around the first pulley 31. Accordingly, the press-contact forces of the left pressurizing roller 331 and the right pressurizing roller 332 against the belt can be adjusted by loosening the bolts and moving the support plate 333 along the elongated hole. In other words, the tension of the belt extending between the guide frame 29 and the first pulley 31 can be adjusted.

[0088] The left pressurizing roller 331 and the right pressurizing roller 332 have the same outer diameter and are supported by the support plate 333 so as to be rotatable about the same axis extending in the left-and-right direction. In addition, the left pressurizing roller 331 and the right pressurizing roller 332 each have a width in the left-and-right direction that is equal to or greater than twice a width of each of the lower belts 21 to 24.

[0089] Accordingly, the left pressurizing roller 331 can be brought into contact with either the rear left lower belt 21 or the front left lower belt 22 wrapped between the guide frame 29 and the first pulley 31.

[0090] Similarly, the right pressurizing roller 332 can be brought into contact with either the front right lower belt 23 or the rear right lower belt 24 wrapped between the guide frame 29 and the first pulley 31.

[0091] The second pressurizing mechanism 34 applies tension to all of the belts, among the lower belts 21 to 24, wrapped between the guide frame 29 and the second pulley 32, thereby suppressing sagging.

[0092] The second pressurizing mechanism 34 includes a left pressurizing roller 341, a right pressurizing roller 342, a support plate 343, and the base block 334 described above, as shown in FIGS. 2, 3, and 6.

[0093] The support plate 343 has the same structure as that of the support plate 333 described above, and is supported by the base block 334 with its longitudinal direction oriented obliquely upward and rearward.

[0094] Additionally, the support plate 343 concentrically and rotatably supports the left pressurizing roller 341 and the right pressurizing roller 342 on left and right surfaces of an upper end portion of the support plate 343. The support plate 343 is arranged such that the left pressurizing roller 341 and the right pressurizing roller 342 come into contact with the outer surface of the belt extending between the guide frame 29 and the second pulley 32 from an upper rear side.

[0095] The support plate 343 also has an elongated hole, and the support plate 343 can be moved along the elongated hole. Accordingly, the contact-press forces of the left pressurizing roller 341 and the right pressurizing roller 342 against the belt wrapped around the second pulley 32 can be adjusted. Therefore, the tension of the belt extending between the guide frame 29 and the second pulley 32 can be adjusted.

[0096] The left pressurizing roller 341 and the right pressurizing roller 342 have the same outer diameter and are supported by the support plate 343 so as to be rotatable about the same axis extending in the left-and-right direction. In addition, the left pressurizing roller 341 and the right pressurizing roller 342 each have a width in the left-and-right direction that is equal to or greater than twice a width of each of the lower belts 21 to 24.

[0097] Accordingly, the left pressurizing roller 341 can be brought into contact with either the rear left lower belt 21 or the front left lower belt 22 wrapped between the guide frame 29 and the second pulley 32.

[0098] Similarly, the right pressurizing roller 342 can be brought into contact with either the front right lower belt 23 or the rear right lower belt 24 wrapped between the guide frame 29 and the second pulley 32.

[0099] Both the left pressurizing roller 331 of the first pressurizing mechanism 33 and the left pressurizing roller 341 of the second pressurizing mechanism 34 can be brought into contact with the rear left lower belt 21 and the front left lower belt 22. Similarly, both the right pressurizing roller 332 of the first pressurizing mechanism 33 and the right pressurizing roller 342 of the second pressurizing mechanism 34 can be brought into contact with the front right lower belt 23 and the rear right lower belt 24.

[0100] Accordingly, each of the lower belts 21 to 24 is provided with tension by either the first pressurizing mechanism 33 or the second pressurizing mechanism 34, regardless of whether it is wrapped around the first pulley 31 or the second pulley 32.

[0101] FIG. 6 shows a state in which the front left lower belt 22 and the front right lower belt 23, which perform feed forward of the stitch point position, are wrapped around the first pulley 31, and the rear left lower belt 21 and the rear right lower belt 24, which perform feed rearward of the stitch point position, are wrapped around the second pulley 32.

[0102] FIG. 7 shows a state in which the rear left lower belt 21 and the front left lower belt 22, which perform feed leftward of the stitch point position, are wrapped around the first pulley 31, and the front right lower belt 23 and the rear right lower belt 24 are wrapped around the second pulley 32.

[0103] When the bolts are loosened and each of the pressurizing rollers 331, 332, 341, and 342 is retracted, each of the lower belts 21 to 24 can be easily removed from each of the pulleys 31 and 32 for replacement and rewrapping.

[0104] Accordingly, it is possible to easily select and perform sewing in the wrapping state of FIG. 6 and sewing in the wrapping state of FIG. 7.

[0105] For example, in the wrapping state of FIG. 6 (a front-and-rear differential feed state), it is possible to perform a so-called shirring stitch in which feed is performed faster on a side forward of the stitch point position than on a side rearward of the stitch point position.

[0106] In addition, in the front-and-rear differential feed state, it is also possible to perform sewing in which feed is performed slower on a side forward of the stitch point position than on a side rearward of the stitch point position and tension is applied to a workpiece.

[0107] In the wrapping state of FIG. 7 (a left-and-right differential feed state), when feed is performed faster on the left side, a curved stitch turning to the right can be performed, and when feed is performed faster on the right side, a curved stitch turning to the left can be performed.

[0108] In addition, since the curvature can be changed depending on the magnitude of the speed difference (difference in conveying amount) between the left and right sides, various curved stitches can be performed.

[0109] In the present embodiment, it is assumed that the sewing machine 100 is used in a left-and-right differential feed state. Therefore, in the following description, each of the lower belts 21 to 24 is assumed to be in the wrapping state of FIG. 7.[Cloth Presser Mechanism]

[0110] FIG. 8 is a perspective view of the cloth presser mechanism 70 as a presser mechanism for pressing a workpiece on the throat plate 101 from above, FIG. 9 is a rear view of the cloth presser mechanism 70, and FIG. 10 is an exploded perspective view of the cloth presser mechanism 70.

[0111] The cloth presser mechanism 70 includes a presser foot 71, a presser bar 72, a mounting base 74, a presser motor 73 (see FIG. 13), and a height sensor 762 (see FIG. 13).

[0112] The presser bar 72 is arranged in front of and adjacent to the needle bar 12 and is supported so as to be movable up and down within the sewing machine arm portion 113 with oriented in the up-and-down direction.

[0113] An upper end portion of the presser bar 72 is pressed downward by a presser spring (not shown) within the sewing machine arm portion 113. An amount of expansion and contraction of the presser spring can be adjusted by the presser motor 73 whose operation amount can be arbitrarily controlled. Therefore, by controlling the presser motor 73, a pressing pressure of the presser foot 71 can be arbitrarily set.

[0114] In addition, the height sensor 762 that detects a height of the presser bar 72 is provided in association with the presser bar 72. Therefore, after setting the pressing pressure of the presser foot 71 to a specified value, when the height sensor 762 detects that a height of the presser foot 71 varies due to a change in thickness of a workpiece, the pressing pressure can be maintained at a constant set value by controlling the presser motor 73 so that the amount of expansion and contraction of the presser spring does not vary.

[0115] The presser foot 71 is provided on a lower end portion of the presser bar 72 via the mounting base 74. The mounting base 74 is a block having horizontal and flat upper and lower surfaces. The mounting base 74 has an insertion hole into which the presser bar 72 can be inserted, the hole penetrating in the up-and-down direction. The mounting base 74 is formed with a slit extending from the insertion hole to an outer edge portion, and is provided with a screw 741 for fastening the slit to narrow its gap width. When the screw 741 is fastened with the lower end portion of the presser bar 72 inserted in the insertion hole, the presser bar 72 can be clamped and fixed. When the screw 741 is loosened, the mounting base 74 can be detached from the presser bar 72.

[0116] The mounting base 74 is attached to the presser bar 72 with the lower end portion of the presser bar 72 slightly protruding beyond a lower surface of the mounting base.

[0117] The lower end portion of the presser bar 72 is attached with its smooth lower surface in contact with an upper flat surface 712d of the presser foot 71.

[0118] A projection 742 that serves as a guide for attaching the upper end portion of the presser foot 71 is formed on a left side surface of the mounting base 74 along the front-and-rear direction of the mounting base 74.

[0119] In addition, a lower end portion of a link member 474 of the upper feed mechanism 40 described below is connected to a front end portion of the mounting base 74 so as to be rotatable about an axis extending along the left-and-right direction of the mounting base 74.

[0120] The presser foot 71 is arranged above the combined opening portion 102 of the throat plate 101. The presser foot 71 presses a workpiece from above to appropriately transmit a conveying force caused by each of the lower belts 21 to 24 to the workpiece. Additionally, the presser foot 71 supports a left upper belt 41 and a right upper belt 42 of the upper feed mechanism 40 so that they can be conveyed. The presser foot 71 also has a function of pressing each of the upper belts 41 and 42 against the workpiece to appropriately transmit the conveying force to the workpiece.

[0121] As shown in FIGS. 8 to 10, the presser foot 71 includes a bottom plate 711 that presses a workpiece from above, and a connecting portion 712 attached to the lower end portion of the presser bar 72.

[0122] The bottom plate 711 is formed in a so-called boat shape with a smooth bottom surface and an upstream side (rear end portion) in a cloth feeding direction curved upward.

[0123] The connecting portion 712 is erected on an upper surface of a front end portion of the bottom plate 711, and is connected to the bottom plate 711 so as to be swingable to some extent about an axis extending along the left-and-right direction. An upper portion of the connecting portion 712 is formed with a flat surface 712d in contact with the lower surface of the lower end portion of the presser bar 72. Additionally, a sidewall 712a is erected on a left end of an upper portion of the connecting portion 712. A right surface of the sidewall 712a is formed with a recessed groove 712b that faces the left side surface of the mounting base 74 and fits with the projection 742.

[0124] The connecting portion 712 is in a correct posture along the vertical up-and-down direction by bringing the flat surface of the upper portion into contact with the lower surface of the mounting base 74 and fitting the projection 742 into the recessed groove 712b.

[0125] Additionally, the sidewall 712a is formed with an insertion hole 712c for a screw 743, the insertion hole penetrating in the left-and-right direction. On the other hand, the left side surface of the mounting base 74 is formed with a screw hole 744. Accordingly, by passing the screw 743 through the insertion hole 712c and fastening it to the screw hole 744, the presser foot 71 can be fixed to the mounting base 74 in a proper position and posture. Note that by loosening the screw 743, the presser foot 71 can be detached from the mounting base 74 and the presser bar 72.[Upper Feed Mechanism]

[0126] As shown in FIGS. 1, 2, and 8 to 10, the upper feed mechanism 40 includes a left upper belt 41 and a right upper belt 42 as conveyor belts, left and right belt guides 43 and 44, a left upper motor 45 as a drive source for belt feed of the left upper belt 41, a right upper motor 46 as a drive source for belt feed of the right upper belt 42, and a guide mechanism 47 that guides each of the upper belts 41 and 42 from each of the upper motors 45 and 46 to the presser foot 71.

[0127] The left and right belt guides 43 and 44 are provided on both the left and right sides of the presser foot 71.

[0128] The respective belt guides 43 and 44 are rotatably attached to left and right side surfaces of a lower portion of the connecting portion 712 of the presser foot 71 by a support shaft 431 extending along the left-and-right direction.

[0129] Each of the belt guides 43 and 44 is configured such that, when viewed from a side, a front end portion extends obliquely upward and forward, a front side of a rear end portion is closest to the throat plate 101, and the rear end portion is raised obliquely upward and rearward. In addition, the rear end portions of the belt guides 43 and 44 are respectively provided with feed rollers 432 and 442 that are rotatable about axes extending along the left-and-right direction.

[0130] The left and right endless loop-shaped upper belts 41 and 42 are guided respectively between the belt guides 43 and 44 and the side surfaces of the presser foot 71. That is, the left upper belt 41, which is a left belt, and the right upper belt 42, which is a right belt, are respectively folded back downward from the upper sides of the feed rollers 432 and 442 along their outer peripheries, are guided to travel forward along the portions of the respective belt guides 43 and 44 that are closest to the throat plate 101, and then proceed obliquely upward and forward. When traveling forward along the portions of the respective belt guides 43 and 44 that are closest to the throat plate 101, each of the upper belts 41 and 42 comes into contact with a workpiece on the throat plate 101 and performs forward feed.

[0131] Additionally, as described above, each of the belt guides 43 and 44 is supported on the presser foot 71 by the support shaft 431. One end portion of each of tension springs 433 and 443 is connected to the front end portion of each of the belt guides 43 and 44. Each of the tension springs 433 and 443 is connected, at its other end portion, to the upper portion of the connecting portion 712 of the presser foot 71 and applies an upward tension to the front end portion of each of the belt guides 43 and 44.

[0132] Accordingly, the rear end portion side of each of the belt guides 43 and 44 is urged to rotate downward, and a contact-press force toward the throat plate 101 is applied to each of the upper belts 41 and 42 traveling forward along the portions closest to the throat plate 101.

[0133] The left and right upper motors 45 and 46 are motors whose rotation speeds can be controlled. As the upper motors 45 and 46, for example, DC motors, AC motors, stepping motors, or the like are used.

[0134] The left upper motor 45 is supported on a front side of the left end portion of the sewing machine arm portion 113 via a motor bracket 451, with its output shaft oriented leftward.

[0135] In addition, the right upper motor 46 is supported above the left upper motor 45 on the front side of the left end portion of the sewing machine arm portion 113 via the motor bracket 451, with its output shaft oriented leftward.

[0136] A motor pulley 452 is mounted on the output shaft of the left upper motor 45, and one end portion of the left upper belt 41 is wound around the motor pulley 452.

[0137] In addition, a motor pulley 462 is mounted on the output shaft of the right upper motor 46, and one end portion of the right upper belt 42 is wound around the motor pulley 462.

[0138] The left upper belt 41 has an endless loop shape, with one end portion wrapped around the motor pulley 452 of the left upper motor 45 and the other end portion wrapped around the feed roller 432 of the belt guide 43, in a stretched state.

[0139] The right upper belt 42 also has an endless loop shape, with one end portion wrapped around the motor pulley 462 of the right upper motor 46 and the other end portion wrapped around the feed roller 442 of the belt guide 44, in a stretched state.

[0140] A path in the left upper belt 41 from the motor pulley 452 to the feed roller 432 and a path in the right upper belt 42 from the motor pulley 462 to the feed roller 442 overlap each other, except for areas around the motor pulleys 452 and 462, when viewed from the left-and-right direction. Note that the right upper belt 42 is arranged on the right side relative to the left upper belt 41.

[0141] The guide mechanism 47 guides the left upper belt 41 and the right upper belt 42 along the respective paths.

[0142] The guide mechanism 47 includes a pair of first tension rollers 471 arranged side by side in the left-and-right direction, a pair of second tension rollers 472 arranged side by side in the left-and-right direction, a guide arm 475 composed of upper and lower link members 473 and 474, and a plurality of guide rollers 476 rotatably provided at each portion on the path of each of the upper belts 41 and 42.

[0143] The pair of first tension rollers 471 is arranged below the motor pulley 452. In addition, the pair of second tension rollers 472 is arranged between the motor pulley 452 and the pair of first tension rollers 471.

[0144] The pair of first tension rollers 471 is rotatable about axes extending along the left-and-right direction, and each roller has a wide axial width. The pair of first tension rollers 471 presses against both the left upper belt 41 and the right upper belt 42 from the outer sides, thereby applying inward tension thereto.

[0145] The pair of second tension rollers 472 is rotatable about axes extending along the left-and-right direction, and each roller has a wide axial width. The pair of second tension rollers 472 presses against only the right upper belt 42 from the inner side, thereby applying outward tension thereto.

[0146] In addition, since the right upper belt 42 can be widened leftward and rightward by the pair of second tension rollers 472, the right upper belt 42 can avoid interference with the motor pulley 452 in the middle of the path.

[0147] The upper link member 473 constituting the guide arm 475 has one end portion connected to a lower end portion of the motor bracket 451 so as to be rotatable about an axis extending along the left-and-right direction. Additionally, the other end portion of the upper link member 473 is connected to one end portion of the lower link member 474 so as to be rotatable about an axis extending along the left-and-right direction.

[0148] In addition, the other end portion of the lower link member 474 is connected to the front end portion of the mounting base 74 so as to be rotatable about the axis extending along the left-and-right direction, as described above.

[0149] At a connecting portion between the upper link member 473 and the lower link member 474, a guide roller 476 is provided to contact the inner side of the loop from the front side, and another guide roller (not shown) is provided to contact the outer side of the loop from the front side, with respect to the left upper belt 41 and the right upper belt 42.

[0150] Accordingly, the left and right upper belts 41 and 42 are conveyed along paths defined by the upper link member 473 and the lower link member 474.

[0151] Therefore, even when the presser foot 71 moves up and down due to changes in the thickness of the workpiece or unevenness and the bending angle between the upper link member 473 and the lower link member 474 changes, the left and right upper belts 41 and 42 still follow the paths defined by the upper link member 473 and the lower link member 474. As a result, the path length of each of the upper belts 41 and 42 is maintained constant, and variation in tension can be suppressed.[End Portion Detection Device]

[0152] FIG. 11 is a perspective view showing the periphery of the throat plate 101 provided with the end portion detection device 80, and FIG. 12 is a rear view of the throat plate 101.

[0153] As illustrated in FIGS. 11 and 12, the end portion detection device 80 includes upper end portion sensors 811 and 812 as upper detection units, lower end portion sensors 821 and 822 as lower detection units, a sensor holding frame 83, an upper guide 84 as a guide, a lower guide 85 as a guide, and a housing 86.

[0154] The housing 86 includes a rectangular top plate portion 861 and two wall portions 862 provided at front and rear end portions of the top plate portion 861. The housing 86 has open bottom and left end portions.

[0155] The housing 86 is arranged on the throat plate 101 such that the entirety thereof is positioned slightly to the right of the stitch point position in the left-and-right direction. In addition, the housing 86 is arranged on the throat plate 101 such that the entirety thereof is positioned slightly rearward (upstream in the feed direction) of the stitch point position in the front-and-rear direction.

[0156] In addition, the front-side and rear-side wall portions 862 of the housing 86 each have a lower end portion of a left end, which is cut away toward the right. The cutout is formed to avoid contact with right end portions of an upper cloth C1 and a lower cloth C2, which serve as workpieces that are fed forward during sewing.

[0157] The housing 86 supports the entire configuration of the end portion detection device 80. The housing 86 is attached to the upper surface of the sewing machine bed portion 111 in the arrangement described above.

[0158] In this case, the housing 86 may be fixed to the upper surface of the sewing machine bed portion 111 by a well-known fixing structure. As a well-known fixing structure, screw fixing or the like can be used. In addition, the entire end portion detection device 80 may be made detachable by providing a permanent magnet at a lower end portion of the housing 86. In this case, it is preferable to provide a structure in which a recess or a projection is formed on the sewing machine bed portion 111 side so as to allow positioning of the housing 86, and the lower end portion of the housing 86 is fitted to the recess or projection to enable positioning.

[0159] The sensor holding frame 83 is supported on a rear surface of the front-side wall portion 862 of the housing 86. At a left end portion of the sensor holding frame 83, an upper wall portion 831, an intermediate wall portion 833, and a lower wall portion 832 are provided side by side in this order from the top, and are formed in a comb-like shape when viewed from the front-and-rear direction. Each of the upper wall portion 831, the intermediate wall portion 833, and the lower wall portion 832 has a plate shape extending in the front-and-rear direction and the left-and-right direction. A left end portion of the upper wall portion 831, a left end portion of the intermediate wall portion 833, and a left end portion of the lower wall portion 832 each extend slightly to the left of the stitch point position.

[0160] A right side end portion of the upper cloth C1, which is fed forward by the upper feed mechanism 40, passes between the upper wall portion 831 and the intermediate wall portion 833.

[0161] Similarly, a right side end portion of the lower cloth C2, which is fed forward by the lower feed mechanism 20, passes between the lower wall portion 832 and the intermediate wall portion 833.

[0162] In order to insert the lower cloth C2 between the lower wall portion 832 and the intermediate wall portion 833, the sensor holding frame 83 is configured such that substantially the entire lower wall portion 832 is housed inside a rectangular opening portion 103 provided in the throat plate 101, and an upper surface of the lower wall portion 832 is flush with the upper surface of the throat plate 101.

[0163] Note that since it is only necessary to ensure a gap sufficient to allow insertion of the lower cloth C2 between a lower surface of the intermediate wall portion 833 and the upper surface of the throat plate 101, the upper surface of the lower wall portion 832 may be positioned lower than the upper surface of the throat plate 101.

[0164] On a lower surface of the upper wall portion 831, upper end portion sensors 811 and 812 that face downward are provided on left and right sides across a position that is located at a predetermined distance S to the right of the stitch point position. The distance S coincides with the target seam allowance of the upper cloth C1 and the lower cloth C2. The seam allowance refers to a distance from an end edge portion of a workpiece to a seam when sewing is performed along the end edge portion.

[0165] The upper end portion sensors 811 and 812 are each constituted by a so-called reflective type photo interrupter in which both a light source and a light-receiving element are oriented downward. An upper surface of the intermediate wall portion 833 is formed as a reflective surface, and the upper end portion sensors 811 and 812 are configured such that the light-receiving element can receive reflected light of the light emitted by the light source.

[0166] Detection outputs from the upper end portion sensors 811 and 812 are input to the control device 90, and the control device 90 can recognize that the right end of the upper cloth C1 is present at the detection position, based on a decrease in the amount of reflected light received.

[0167] The upper end portion sensors 811 and 812 are respectively provided slightly to the left or right of a position corresponding to the distance S. That is, the upper end portion sensors 811 and 812 define an allowable range within which the right end portion of the upper cloth C1 can be considered to be positioned at the distance S.

[0168] During sewing, the control device 90 performs control to move the upper cloth C1 rightward when the right end portion of the upper cloth C1, having entered between the upper wall portion 831 and the intermediate wall portion 833 from the left, is no longer detected by the left upper end portion sensor 811, and performs control to move the upper cloth C1 leftward when the right end portion of the upper cloth C1 is detected by the right upper end portion sensor 812. Accordingly, control is performed to maintain the right end of the upper cloth C1 between the upper end portion sensors 811 and 812 on the left and right sides.

[0169] On the upper surface of the lower wall portion 832, lower end portion sensors 821 and 822 that face upward are provided on left and right sides across a position that is located at the predetermined distance S to the right of the stitch point position.

[0170] The lower end portion sensors 821 and 822 are also each constituted by a reflective type photo interrupter. The intermediate wall portion 833 also has a lower surface formed as a reflective surface.

[0171] In the case of the lower end portion sensors 821 and 822, the control device 90 can also recognize that the right end of the lower cloth C2 is present at the detection position, based on a decrease in the amount of reflected light received.

[0172] The left-and-right arrangement of the lower end portion sensors 821 and 822 is the same as that of the upper end portion sensors 811 and 812, and defines an allowable range within which the right end portion of the lower cloth C2 can be considered to be positioned at the distance S.

[0173] During sewing, the control device 90 performs control to move the lower cloth C2 rightward when the right end portion of the lower cloth C2, having entered between the lower wall portion 832 and the intermediate wall portion 833 from the left, is no longer detected by the left lower end portion sensor 821, and performs control to move the lower cloth C2 leftward when the right end portion of the lower cloth C2 is detected by the right lower end portion sensor 822. Accordingly, control is performed to maintain the right end of the lower cloth C2 between the lower end portion sensors 821 and 822 on the left and right sides.

[0174] Note that the upper end portion sensors 811 and 812 and the lower end portion sensors 821 and 822 are not limited to the photo interrupters, and any detection means capable of detecting a cloth end can be used. For example, a microswitch or the like may be used to detect that a seam allowance exceeds the distance S when the right end portion of the upper cloth C1 or the lower cloth C2 comes into contact from the left.

[0175] Both the upper guide 84 and the lower guide 85 are plate-shaped guides.

[0176] The upper guide 84 is provided to guide the upper cloth C1 between the upper wall portion 831 and the intermediate wall portion 833 of the sensor holding frame 83.

[0177] The lower guide 85 is provided to guide the lower cloth C2 between the lower wall portion 832 and the intermediate wall portion 833 of the sensor holding frame 83. The lower guide 85 also has a function of separating the upper cloth C1 and the lower cloth C2.

[0178] The lower guide 85 extends rearward and leftward with respect to the intermediate wall portion 833. The lower guide 85 is formed to have substantially the same thickness as that of the intermediate wall portion 833. An upper surface of the lower guide 85 is supported inside the housing 86 so as to be at the same height as the upper surface of the intermediate wall portion 833, and the lower surface of the lower guide 85 is supported inside the housing 86 so as to be at the same height as the lower surface of the intermediate wall portion 833.

[0179] Additionally, rear and left extension end portions of the lower guide 85 are formed to be slightly bent or curved upward. This facilitates feed of the lower cloth C2 to the lower side of the lower guide 85 during sewing.

[0180] The upper guide 84 extends rearward and leftward from the upper wall portion 831. A lower surface of the upper guide 84 is supported inside the housing 86 so as to be at the same height as the lower surface of the upper wall portion 831.

[0181] Additionally, rear and left extension end portions of the upper guide 84 are formed to be slightly bent or curved upward. This facilitates feed of the lower cloth C2 between the upper guide 84 and the lower guide 85 during sewing.[Control System of Sewing Machine]

[0182] FIG. 13 is a block diagram showing a control system of the sewing machine 100.

[0183] As shown in FIG. 13, the sewing machine 100 includes the control device 90 that controls an operation of each configuration. The sewing machine motor 16, the presser motor 73, the first motor 25, the second motor 26, the left upper motor 45, and the right upper motor 46 are connected to the control device 90 via motor drive circuits 16a, 73a, 25a, 26a, 45a, and 46a, respectively.

[0184] In addition, the sewing machine motor 16, the presser motor 73, the first motor 25, the second motor 26, the left upper motor 45, and the right upper motor 46 are provided with encoders 161, 732, 251, 261, 451, and 461 for detecting their respective rotational speeds. The encoders 161, 732, 251, 261, 451, and 461 are also connected to the control device 90 via motor drive circuits 16a, 73a, 25a, 26a, 45a, and 46a, respectively.

[0185] The control device 90 includes a CPU 91, a ROM 92, a RAM 93, and an EEPROM (registered trademark) 94, and executes various operation controls described below.

[0186] A basic system program is stored in the ROM 92.

[0187] Additionally, various setting data, other programs, and the like are stored in the EEPROM 94. Note that the various setting data and programs may be stored in a nonvolatile memory device such as a flash memory, an EPROM, an HDD, or the like, instead of the EEPROM.

[0188] The CPU 91 executes various programs in the ROM 92 and the EEPROM 94. The RAM 93 is a memory that serves as a working area for the CPU 91.

[0189] Additionally, an operation input unit 96 is connected to the control device 90 via an interface 96a.

[0190] The operating input unit 96 includes an input screen 961. Information necessary for inputting various settings is displayed on the input screen 961.

[0191] In addition, set values of a stitch pitch, a pressing pressure during sewing by the cloth presser mechanism 70, and the like can be input from the operation input unit 96.

[0192] In addition, a pedal 95 that inputs operations such as start and stop of sewing and increase / decrease in sewing speed by a depression operation is connected to the control device 90 via an interface 95a.

[0193] In addition, the height sensor 762 that detects a height of the presser foot 71, the upper end portion sensors 811 and 812, and the lower end portion sensors 821 and 822 are connected to the control device 90 via interfaces 762a, 811a, 812a, 821a, and 822a.[Sewing Control]

[0194] Here, sewing control of a workpiece performed based on a control program 941 will be described. FIG. 14 is a flowchart showing a process that is performed by the CPU 91 executing the control program 941.

[0195] First, an operator of the sewing machine feeds the lower cloth C2 between the lower guide 85 and the throat plate 101, feeds the upper cloth C1 between the upper guide 84 and the lower guide 85, and depresses the pedal 95.

[0196] In contrast, the CPU 91 of the control device 90 waits while monitoring the depression of the pedal 95 (step S1). When the CPU 91 detects the depression of the pedal 95, the CPU reads the set value of the feed pitch in the EEPROM 94 (step S3).

[0197] Then, the CPU 91 drives the sewing machine motor 16 at a speed corresponding to the amount of depression of the pedal 95 (step S5). Additionally, the CPU 91 starts driving the left upper motor 45, the right upper motor 46, the first motor 25, and the second motor 26 at a speed at which stitch points are performed at the set feed pitch (step S7).

[0198] Accordingly, the upper cloth C1 and the lower cloth C2 are each individually fed forward.

[0199] Next, the CPU 91 determines whether the right end portion of the upper cloth C1 is detected by the left upper end portion sensor 811 (step S9). In step S9, when the right end portion of the upper cloth C1 is detected, the CPU 91 determines whether the right end portion of the upper cloth C1 is detected by the right upper end portion sensor 812 (step S10).

[0200] When the right end portion of the upper cloth C1 is also detected by the right upper end portion sensor 812, the CPU 91 determines that the upper cloth C1 is excessively shifted to the right.

[0201] Therefore, the CPU 91 executes differential feed so that the rotation speed of the right upper motor 46 becomes higher than that of the left upper motor 45, while setting the average of the rotation speeds of the left and right upper motors 45 and 46 to a rotation speed that maintains the set feed pitch (step S11). Accordingly, the upper cloth C1 is fed while being shifted to the left. Then, the CPU 91 proceeds to step S15.

[0202] In addition, in step S9, when the right end portion of the upper cloth C1 is not detected by the left upper end portion sensor 811, the CPU 91 determines that the upper cloth C1 is excessively shifted to the left.

[0203] Therefore, the CPU 91 executes differential feed so that the rotation speed of the left upper motor 45 becomes higher than that of the right upper motor 46, while setting the average of the rotation speeds of the left and right upper motors 45 and 46 to a rotation speed that maintains the set feed pitch (step S13). Accordingly, the upper cloth C1 is fed while being shifted to the right. Then, the CPU 91 proceeds to step S15.

[0204] In addition, in step S10, when the right end portion of the upper cloth C1 is not detected by the right upper end portion sensor 812, the CPU 91 determines that the right end portion of the upper cloth C1 is present at a proper position, and proceeds to step S15.

[0205] Next, the CPU 91 determines whether the right end portion of the lower cloth C2 is detected by the left lower end portion sensor 821 (step S15). In step S15, when the right end portion of the lower cloth C2 is detected, the CPU 91 determines whether the right end portion of the lower cloth C2 is detected by the right lower end portion sensor 822 (step S16).

[0206] When the right end portion of the lower cloth C2 is also detected by the right lower end portion sensor 822, the CPU 91 determines that the lower cloth C2 is excessively shifted to the right.

[0207] Therefore, the CPU 91 executes differential feed so that the rotation speed of the second motor 26 becomes higher than that of the first motor 25, while setting the average of the rotation speeds of the first and second motors 25 and 26 to a rotation speed that maintains the set feed pitch (step S17). Accordingly, the lower cloth C2 is fed while being shifted to the left. Then, the CPU 91 proceeds to step S21.

[0208] In addition, in step S15, when the right end portion of the lower cloth C2 is not detected by the left lower end portion sensor 821, the CPU 91 determines that the lower cloth C2 is excessively shifted to the left.

[0209] Therefore, the CPU 91 executes differential feed so that the rotation speed of the first motor 25 becomes higher than that of the second motor 26, while setting the average of the rotation speeds of the first and second motors 25 and 26 to a rotation speed that maintains the set feed pitch (step S19). Accordingly, the lower cloth C2 is fed while being shifted to the right. Then, the CPU 91 proceeds to step S21.

[0210] Note that the differential amounts in steps S11, S13, S17, and S19 may be arbitrarily set in advance from the operation input unit 96.

[0211] In addition, in step S16, when the right end portion of the lower cloth C2 is not detected by the right lower end portion sensor 822, the CPU 91 determines that the right end portion of the lower cloth C2 is present at a proper position, and proceeds to step S21.

[0212] Then, the CPU 91 determines whether the depression of the pedal 95 is released (step S21). In step S21, when the depression of the pedal 95 is not released, the CPU 91 returns the process to step S9 and continues the sewing while correcting the left-and-right shifts of the upper cloth C1 and the lower cloth C2 again.

[0213] In addition, when the depression of the pedal 95 is released, the CPU 91 stops driving the left upper motor 45, the right upper motor 46, the first motor 25, the second motor 26, and the sewing machine motor 16, thereby ending the sewing.[Technical Effects of Embodiment of Present Disclosure]

[0214] As described above, the sewing machine 100 is configured such that the control device 90 controls the upper feed mechanism 40 and the lower feed mechanism 20, based on detection by the end portion detection device 80, to generate a difference in the feed amount in the stitch direction between the left and right sides of the upper cloth C1 and the lower cloth C2.

[0215] Accordingly, unlike the related art in which a path is corrected by forcibly applying a feed operation in a direction orthogonal to the main feed direction, which is straight, the upper cloth C1 and the lower cloth C2 can maintain a constant seam allowance while smoothly changing path.

[0216] As a result, high-quality stitching can be achieved even when performing curved sewing.

[0217] In addition, the lower feed mechanism 20 includes the rear left lower belt 21 and the front left lower belt 22 as left belts, and the front right lower belt 23 and the rear right lower belt 24 as right belts, thereby enabling belt feed. Accordingly, unlike a case where the feeding dots are pressed, even when the lower cloth C2 is a relatively thin or delicate fabric, it is possible to feed the lower cloth properly while protecting the lower cloth.

[0218] In addition, the upper feed mechanism 40 includes the left upper belt 41 as a left upper belt and the right upper belt 42 as a right belt, thereby enabling belt feed. Accordingly, unlike a case where the feeding dots are pressed, even when the upper cloth C1 is a relatively thin or delicate fabric, it is possible to feed the upper cloth properly while protecting the upper cloth.

[0219] In addition, the end portion detection device 80 includes the upper end portion sensors 811 and 812 that detect an end portion of the upper cloth C1 overlapped on the upper side, and the lower end portion sensors 821 and 822 that detect an end portion of the lower cloth C2 overlapped on the lower side.

[0220] Therefore, the end portion detection device 80 can individually detect the end portion positions of the upper cloth C1 and the lower cloth C2, allowing the paths of the upper and lower cloths to be corrected independently and their seam allowances to be maintained constant.

[0221] As a result, even when the side end portions of the upper cloth C1 and the lower cloth C2 have different shapes, high-quality stitching can be achieved.

[0222] In addition, the end portion detection device 80 includes the lower guide 85 that separates the lower cloth C2 and the upper cloth C1, on the upstream side in the feed direction with respect to the upper end portion sensors 811 and 812 and the lower end portion sensors 821 and 822. Accordingly, since the side end portions of the lower cloth C2 and the upper cloth C1 do not interfere with each other and can be individually detected, the accuracy of end portion detection is improved, and it becomes possible to perform sewing in which the seam allowances of the lower cloth C2 and the upper cloth C1 are precisely and independently maintained constant. As a result, higher-quality stitching can be achieved.

[0223] In addition, the lower guide 85 can suppress the lower cloth C2 and the upper cloth C1 from sliding due to contact and dragging each other. Additionally, since the side end portions of the lower cloth C2 and the upper cloth C1 are accurately positioned in the left-and-right direction, the cloths can be sewn favorably together even when the shapes of the side end portions are different, and higher-quality stitching can be achieved.[Other Forms of End Portion Detection Device]

[0224] The end portion detection device 80 is not limited to the configuration described above.

[0225] For example, instead of the upper end portion sensors 811 and 812 and the lower end portion sensors 821 and 822 provided on the sensor holding frame 83, three or more upper end portion sensors 81 and lower end portion sensors 82 arranged at equal intervals in the left-and-right direction may be used as shown in FIG. 15.

[0226] In this case, when the upper end portion sensors 81 and the lower end portion sensors 82 are composed of an odd number of sensors, the sensors are arranged such that a sensor located at the center in the left-and-right direction is present at the target seam allowance position (position at the distance s). In addition, when the upper end portion sensors 81 and the lower end portion sensors 82 are composed of an even number of sensors, the sensors are arranged such that an equal number of sensors are aligned on both the left and right sides of a sensor located at the center in the left-and-right direction, which corresponds to the target seam allowance position (position at the distance S).

[0227] The control device 90 preferably performs control on the left upper motor 45 and the right upper motor 46 such that, when the cloth end of the upper cloth C1 or the lower cloth C2 is significantly shifted from the target cloth end position of the seam allowance, the amount of differential feed between the left and right sides is increased, and when the shift is small, the amount of differential feed is decreased.

[0228] Note that, instead of the plurality of upper end portion sensors 81 or lower end portion sensors 82 arranged in the left-and-right direction, a linear light-receiving sensor having a plurality of light-receiving elements as detection units arranged in the left-and-right direction may be used.

[0229] In addition, among the plurality of upper end portion sensors 81 and lower end portion sensors 82 arranged in the left-and-right direction, one of each may be selectively used to perform sewing using the position of the selected sensor as the seam allowance. In this case, sewing with multiple seam allowance widths can be performed based on the arrangement of the plurality of upper end portion sensors 81 and lower end portion sensors 82 arranged in the left-and-right direction.

[0230] Alternatively, two adjacent sensors may be selectively used among the upper end portion sensors 81 and the lower end portion sensors 82 arranged in the left-and-right direction, and sewing may be performed using the intermediate position between the two selected sensors as the seam allowance. Also in this case, sewing with multiple seam allowance widths can be performed based on the arrangement of the plurality of upper end portion sensors 81 and lower end portion sensors 82 arranged in the left-and-right direction.

[0231] In addition, when the above-described linear light-receiving sensor is used, it is possible to set the seam allowance with higher resolution and to perform sewing accordingly.

[0232] Additionally, the upper end portion sensor 81 and the lower end portion sensor 82 may be provided in plurality in the feed direction. In this case, by identifying in advance the positions of the upper cloth C1 and the lower cloth C2 upstream in the feed direction, the differential feed effect can be moderated, which makes it possible to prevent stitch line wavering and wrinkling of the upper cloth C1 and the lower cloth C2.

[0233] In addition, the end portion detection device 80 may be configured to be mounted on the upper surface of the sewing machine bed portion 111 such that its position can be adjusted in the left-and-right direction. For example, when the housing 86 is installed on the upper surface of the sewing machine bed portion 111, a plurality of positioning holes or a plurality of positioning recesses arranged in the left-and-right direction may be provided in one of the housing 86 or the sewing machine bed portion 111, and a pin insertable into the positioning holes or a projection fittable into the positioning recesses may be provided in the other. Accordingly, by selecting one of the plurality of positioning holes or the plurality of positioning recesses and fitting the pin or projection therein, the end portion detection device 80 can be arranged at a selected one of a plurality of positions in the left-and-right direction.

[0234] By selecting any desired arrangement in the left-and-right direction, it becomes possible to perform sewing with a seam allowance of any desired width.

[0235] In addition, the end portion detection device 80 may be provided on the upper surface of the sewing machine bed portion 111 so as to be movable in the left-and-right direction, and may be configured to be arbitrarily positioned in the left-and-right direction by a position adjustment mechanism including a motor whose amount of operation can be controlled. In this case, it is preferable that any value of a seam allowance can be set via the operation input unit 96, and that the control device 90 perform operation control to position the end portion detection device 80 in the left-and-right direction by the motor, in accordance with the set value of the seam allowance.

[0236] In addition, the end portion detection device 80 is fixedly mounted on the upper surface of the sewing machine bed portion 111, and the housing 86 supports the sensor holding frame 83 so as to be movable in the left-and-right direction. Furthermore, the sensor holding frame 83 may be configured to be arbitrarily positioned in the left-and-right directions by a motor whose amount of operation can be controlled.

[0237] In addition, although the configuration in which the upper cloth C1 and the lower cloth C2 are sewn with the same seam allowance dimension has been exemplified, sewing may instead be performed with different seam allowance dimensions for the upper cloth C1 and the lower cloth C2 by changing the sensor positions in the up-and-down direction. Furthermore, as described above, when the sensor positions are made movable in the left-and-right directions, it is preferable to allow the sensor positions on the upper and lower sides to be independently movable.[Mounting Example of Air Supply Device]

[0238] FIG. 16 is a perspective view illustrating an example in which a plurality of air outlets 104 are provided in an upper surface (a conveying surface for a workpiece) of the sewing machine bed portion 111 continuous with the throat plate 101, and an air supply device is provided to supply air from each of the air outlets 104.

[0239] In this case, the configuration includes an air source such as a fan or a high-pressure air tank that supplies air at a pressure higher than atmospheric pressure, a conduit that connects the air source to each of the air outlets 104, an electromagnetic valve capable of switching between connection and disconnection between each air outlet 104 and the air source, and the like. The control device 90 controls the electromagnetic valve during sewing to eject air from each outlet 104.

[0240] Accordingly, air is introduced between the lower cloth C2 and upper cloth C1 and the upper surfaces of the throat plate 101 and the sewing machine bed portion 111, thereby reducing sliding friction therebetween and allowing smooth feed and direction correction of the lower cloth C2 and the upper cloth C1.

[0241] Accordingly, the feed direction can be favorably corrected, and the seam allowance can be stably maintained at a target value, thereby enabling higher-quality stitching.[Others]

[0242] Each embodiment of the present disclosure has been described. However, the present disclosure is not limited to the above embodiments. For example, in the above embodiments, a component integrally formed by a single member may be replaced with a component divided into a plurality of members and connected or fixed to each other. Additionally, a component formed by connecting a plurality of members may be replaced with a component formed integrally by a single member. In addition, the details described in the embodiments may be appropriately changed without departing from the spirit of the invention.

[0243] In addition, although the sewing machine 100 has been exemplified as having the configuration including both the upper feed mechanism 40 and the lower feed mechanism 20, only one of the mechanisms may be provided. In this case, when the shapes of the side end portions of the upper cloth C1 and the lower cloth C2 are different, it is difficult to perform sewing. However, when the shapes of the side end portions match, it is possible to perform sewing in which the seam allowance can be maintained at a target value.

[0244] In addition, the sewing machine 100 may be configured to include the upper feed mechanism 40 and a lower feed mechanism of the related art using feeding dots that does not perform differential feed. In addition, the sewing machine 100 may be configured to include the lower feed mechanism 20 and an upper feed mechanism of the related art with feed feet that performs feed from above without performing differential feed.

[0245] In addition, as in each of the above examples, when left-and-right differential feed is performed by only one of the upper or lower mechanisms, the end portion detection device may be configured to detect a side end portion of any one of the upper cloth C1 and the lower cloth C2 without separating the cloths.

[0246] In addition, although the configuration in which belt feed is performed as the lower feed mechanism 20 has been exemplified, no such limitation is intended. For example, feeding dots for which the control device 90 can perform control to change the feed pitch independently on the left and right sides may be arranged on both left and right sides of the stitch point position of the stitch needle 11, and left-and-right differential feed may be performed by the feeding dots on the left and right sides.

[0247] In addition, although the configuration in which belt feed is performed as the upper feed mechanism 40 has been exemplified, no such limitation is intended. For example, feed feet for which the control device 90 can perform control to change the feed pitch independently on the left and right sides may be arranged on both left and right sides of the stitch needle 11, and left-and-right differential feed may be performed by the feed feet on the left and right sides.

[0248] Additionally, a belt feed mechanism of the related art may be used instead of the configuration in which the presser foot 71 can be detached from the mounting base 74 and the presser bar 72.

[0249] The present application is based on Japanese Patent Application No. 2023-056875 filed on March 31, 2023, the contents of which are incorporated herein by reference.

Examples

Embodiment Construction

[Schematic Configuration of Embodiment]

[0009]Hereinafter, a sewing machine, which is an embodiment of the present disclosure, will be described in detail.

[0010]FIG. 1 shows a rear view of a sewing machine 100, FIG. 2 shows a left side view of the sewing machine 100, and FIG. 3 shows a perspective view of the sewing machine 100.

[0011]Hereinafter, the downstream side of the feed direction of the workpiece is referred to as "front", the upstream side of the feed direction is referred to as "rear", the left side when facing forward is referred to as "left", the right side is referred to as "right", the vertically upward direction is referred to as "up", and the vertically downward direction is referred to as "down". The front-and-rear, left-and-right, and up-and-down directions are orthogonal to each other.

[0012]In the following description, it is assumed that the sewing machine 100 is installed on a horizontal plane, and the front-and-rear and left-and-right directions are horizontal.

[...

TECHNICAL FIELD

[0001] The present disclosure relates to a sewing machine that performs left-and-right differential feed.BACKGROUND ART

[0002] A sewing machine of the related art performs sewing while moving a workpiece on a throat plate, which is fed in a stitch direction by feeding dots, by a roller mechanism that feeds the workpiece in a direction orthogonal to a feed direction by the feeding dots, thereby aligning a position of a side end portion of the workpiece to a proper position (see, for example, Patent Literature 1).CITATION LISTPATENT LITERATURE

[0003] Patent Literature 1: JP2013-059577ASUMMARY OF INVENTIONTECHNICAL PROBLEM

[0004] In the configuration of the above-described sewing machine of the related art, since the roller mechanism is configured to perform feed in the direction orthogonal to the feed direction by the feeding dots, there is a risk that feed by the feeding dots will be affected.

[0005] An object of the present disclosure is to smoothly feed a workpiece while aligning a side end portion of the workpiece to a proper position.SOLUTION TO PROBLEM

[0006] The present disclosure provides a sewing machine including: a feed mechanism configured to feed a workpiece on a throat plate in a stitch direction; and an end portion detection device configured to detect an end portion of the workpiece in a direction orthogonal to the stitch direction, in which the feed mechanism enables differential feed, creating a variance in feed amount in the stitch direction between the left and right sides of the stitch point position, and the sewing machine includes a control device configured to control the difference in feed amount in the stitch direction between the left and right sides by the feed mechanism, based on detection by the end portion detection device. ADVANTAGEOUS EFFECTS OF INVENTION

[0007] The sewing machine of the present disclosure allows smooth feed of a workpiece while aligning a side end portion of the workpiece to a proper position.BRIEF DESCRIPTION OF DRAWINGS

[0008] [FIG. 1] FIG. 1 is a rear view of a sewing machine according to an embodiment of the present disclosure. [FIG. 2] FIG. 2 is a left side view of the sewing machine. [FIG. 3] FIG. 3 is a perspective view of the sewing machine. [FIG. 4] FIG. 4 is a perspective view showing an upper surface of a left end portion of a sewing machine bed portion (a presser foot is not shown). [FIG. 5] FIG. 5 is a perspective view of a guide frame of a lower feed mechanism. [FIG. 6] FIG. 6 is a perspective view of a feed mechanism in which four conveyor belts are in a front-and-rear differential feed state. [FIG. 7] FIG. 7 is a perspective view of the feed mechanism in which the four conveyor belts are in a left-and-right differential feed state. [FIG. 8] FIG. 8 is a perspective view of a cloth presser mechanism that presses a workpiece on a throat plate from above. [FIG. 9] FIG. 9 is a rear view of the cloth presser mechanism. [FIG. 10] FIG. 10 is an exploded perspective view of the cloth presser mechanism. [FIG. 11] FIG. 11 is a perspective view showing the periphery of a throat plate provided with an end portion detection device. [FIG. 12] FIG. 12 is a rear view showing the periphery of the throat plate provided with the end portion detection device. [FIG. 13] FIG. 13 is a block diagram showing a control system of the sewing machine. [FIG. 14] FIG. 14 is a flowchart showing sewing operation control that is executed by a control device. [FIG. 15] FIG. 15 is a rear view of a sensor holding frame, which is another form of the end portion detection device. [FIG. 16] FIG. 16 is a perspective view of a sewing machine having a plurality of air outlets provided in an upper surface of a sewing machine bed portion. DESCRIPTION OF EMBODIMENTS[Schematic Configuration of Embodiment]

[0009] Hereinafter, a sewing machine, which is an embodiment of the present disclosure, will be described in detail.

[0010] FIG. 1 shows a rear view of a sewing machine 100, FIG. 2 shows a left side view of the sewing machine 100, and FIG. 3 shows a perspective view of the sewing machine 100.

[0011] Hereinafter, the downstream side of the feed direction of the workpiece is referred to as "front", the upstream side of the feed direction is referred to as "rear", the left side when facing forward is referred to as "left", the right side is referred to as "right", the vertically upward direction is referred to as "up", and the vertically downward direction is referred to as "down". The front-and-rear, left-and-right, and up-and-down directions are orthogonal to each other.

[0012] In the following description, it is assumed that the sewing machine 100 is installed on a horizontal plane, and the front-and-rear and left-and-right directions are horizontal.

[0013] As the sewing machine 100, which is an embodiment of the present disclosure, a lockstitch sewing machine having a function of differential feed is exemplified.

[0014] The sewing machine 100 includes a needle up-and-down movement mechanism, a lower feed mechanism 20 as a feed mechanism, an upper feed mechanism 40 as a feed mechanism, a cloth presser mechanism 70 as a presser mechanism, a shuttle mechanism, an end portion detection device 80, and a control device 90. The end portion detection device 80 is shown in FIG. 11, and is not shown in FIGS. 1 to 10.

[0015] The needle up-and-down movement mechanism applies an up-and-down movement to a stitch needle 11.

[0016] The lower feed mechanism 20 applies a feed operation from below to a workpiece on a throat plate 101.

[0017] The upper feed mechanism 40 applies a feed operation from above to the workpiece on the throat plate 101.

[0018] The cloth presser mechanism 70 applies pressing pressure to the workpiece on the throat plate 101.

[0019] The shuttle mechanism captures a loop of upper thread from the stitch needle 11 and entwines it with a lower thread, thereby forming a seam.

[0020] The end portion detection device 80 detects positions, in the left-and-right direction on the throat plate 101, of respective side end portions (right end portions) of an upper cloth C1 (see FIG. 12) as an upper workpiece and a lower cloth C2 (see FIG. 12) as a lower workpiece.

[0021] The control device 90 executes operation control of each of the above components.

[0022] Note that the sewing machine 100 includes various components such as a thread take-up lever mechanism and a thread tensioner, which are included in general lockstitch sewing machines. However, the descriptions thereof are omitted as they are well-known in the art.[Sewing Machine Frame]

[0023] The sewing machine frame 110 supports or houses each component of the sewing machine 100 described above.

[0024] The sewing machine frame 110 includes a sewing machine bed portion 111, an upright drum portion 112, and a sewing machine arm portion 113.

[0025] The sewing machine bed portion 111 is located at a lower portion of the sewing machine 100 and extends in the left-and-right direction.

[0026] The upright drum portion 112 is erected from a right end portion of the sewing machine bed portion 111.

[0027] The sewing arm portion 113 extends leftward from an upper end portion of the upright drum portion 112.[Needle Up-and-Down Movement Mechanism]

[0028] FIG. 4 is a perspective view showing an upper surface of a left end portion of the sewing machine bed portion 111. In FIG. 4, a presser foot described below is omitted.

[0029] As shown in FIGS. 1 to 4, the needle up-and-down movement mechanism includes an upper shaft that is arranged inside the sewing machine arm portion 113, is rotationally driven by a sewing machine motor, and extends in the left-and-right direction.

[0030] In addition, the needle up-and-down movement mechanism includes a needle bar 12 that holds the stitch needle 11 at a lower end portion, and a crank mechanism that converts rotational force of the upper shaft into a reciprocating drive force for up-and-down movement and transmits the force to the needle bar.

[0031] Note that illustrations of the upper shaft and the crank mechanism are omitted because they are well known in the art.

[0032] The needle bar 12 extends in the up-and-down direction and is supported at a lower left end portion of the sewing machine arm portion 113 so as to be movable up and down.

[0033] The stitch needle 11 is held at a lower end portion of the needle bar 12 and moves up and down together with the needle bar 12. Below the needle bar 12 on an upper surface of the sewing machine bed portion 111, a throat plate 101 made of a horizontal flat plate is provided.

[0034] A combined opening portion 102 is formed at a stitch point position of the stitch needle 11 with respect to the throat plate 101. In the combined opening portion 102 of the throat plate 101, an eye member 30 having an eye 13, a rear left lower belt 21 and a front left lower belt 22 as left belts of the lower feed mechanism 20 described below, and a front right lower belt 23 and a rear right lower belt 24 as right belts are arranged to be exposed upward. That is, the combined opening portion 102 has a shape in which a plurality of rectangular opening portions through which the eye member 30 and each of the lower belts 21 to 24 are exposed are integrally combined.[Shuttle Mechanism]

[0035] As shown in FIGS. 2 and 3, the shuttle mechanism includes an outer shuttle 14 and an inner shuttle 15 provided on a lower side of the eye member 30 of the throat plate 101, and a shuttle shaft (not shown) for rotating the inner shuttle 15.

[0036] The shuttle shaft is rotatably supported within the sewing machine bed portion 111, while extending in the left-and-right direction. Rotation about an axis extending in the left-and-right direction, which is transmitted from the upper shaft and increased to a speed twice that of the upper shaft via a gear mechanism or a belt mechanism, is input to the shuttle shaft.

[0037] The inner shuttle 15 is housed inside the outer shuttle 14. Additionally, the inner shuttle 15 houses a bobbin (not shown) that supplies a lower thread inside the inner shuttle.

[0038] The outer shuttle 14 is connected to a left end portion of the shuttle shaft and rotates around the inner shuttle. The inner shuttle 15 is restricted from rotating so as not to rotate together with the outer shuttle 14. The outer shuttle 14 has a hook for capturing a loop of upper thread from the stitch needle 11 at an outer periphery thereof. By rotating, the outer shuttle 14 is capable of capturing a loop of upper thread with its hook and passing the loop under a lower thread reeled out from inside the inner shuttle 15.

[0039] The outer shuttle 14 and the inner shuttle 15 are arranged in a housed state inside a substantially cylindrical guide frame 29 of the lower feed mechanism 20 described below.[Lower Feed Mechanism]

[0040] FIG. 5 is a perspective view of the guide frame 29 of the lower feed mechanism 20, and FIGS. 6 and 7 are perspective views of the lower feed mechanism 20. FIGS. 6 and 7 show different wrapping states of the respective lower belts 21 to 24 described below.

[0041] Below, the lower feed mechanism 20 will be described in detail based on FIGS. 1 to 7.

[0042] As shown in each drawing, the lower feed mechanism 20 includes each of lower belts 21 to 24 as conveyor belts, a first motor 25, a second motor 26, rotation shafts 27 and 28, a first pulley 31, and a second pulley 32.

[0043] In addition, the lower feed mechanism 20 includes a guide frame 29 that guides each of the lower belts 21 to 24 to come into contact with a lower surface of a workpiece, a first pressurizing mechanism 33, and a second pressurizing mechanism 34.

[0044] Both the first motor 25 and the second motor 26 are motors whose operation amount can be arbitrarily controlled. The first motor 25 and the second motor 26 are, for example, DC motors, AC motors, stepping motors, or the like. The first motor 25 and the second motor 26 are arranged inside a right end portion of the sewing machine bed portion 111 in a state of being aligned in the front-and-rear direction, with output shafts oriented leftward.

[0045] The first pulley 31 is connected to the output shaft of the front-side first motor 25 via the rotation shaft 27.

[0046] The second pulley 32 is connected to the output shaft of the rear-side second motor 26 via the rotation shaft 28.

[0047] Both the rotation shafts 27 and 28 are parallel in the left-and-right direction and are rotatably supported within the sewing machine bed portion 111.

[0048] The first pulley 31 and the second pulley 32 are rotatably supported about axes extending in the left-and-right directions within a left end portion of the sewing machine bed portion 111. The first pulley 31 and the second pulley 32 are rotationally driven by the first motor 25 and the second motor 26 via the rotation shafts 27 and 28, respectively.

[0049] The first pulley 31 and the second pulley 32 are arranged in an overlapping manner when viewed from the front-and-rear direction, i.e., are positioned at the same height and at the same location in the left-and-right direction. Additionally, the first pulley 31 is arranged forward of the second pulley 32.

[0050] Both the first pulley 31 and the second pulley 32 can be wrapped with all of the lower belts 21, 22, 23, and 24, which are arranged in parallel in the left-and-right direction.

[0051] That is, the first pulley 31 has, on its outer peripheral surface, a left groove 311 for wrapping the rear left lower belt 21 and the front left lower belt 22, and a right groove 312 for wrapping the front right lower belt 23 and the rear right lower belt 24.

[0052] The second pulley 32 has, on its outer peripheral surface, a left groove 321 for wrapping the rear left lower belt 21 and the front left lower belt 22, and a right groove 322 for wrapping the front right lower belt 23 and the rear right lower belt 24.

[0053] Each of the lower belts 21 to 24 has the same width, and the left grooves 311 and 321 and the right grooves 312 and 322 all have a width corresponding to at least two belts.

[0054] Accordingly, each of the lower belts 21 to 24 can be selectively wrapped around the first pulley 31 or the second pulley 32.

[0055] Each of the lower belts 21, 22, 23 and 24 has an endless loop shape and is wrapped between the guide frame 29 and the first pulley 31 or between the guide frame 29 and the second pulley 32.

[0056] In addition, the respective lower belts 21, 22, 23, and 24 are arranged in parallel in the order from left to right.

[0057] As shown in FIG. 2, the guide frame 29 (guide member) is arranged so as to substantially coincide with the first pulley 31 and the second pulley 32 in the left-and-right direction and to be located between the first pulley 31 and the second pulley 32 in the front-and-rear direction. Additionally, the guide frame 29 is arranged above the first pulley 31 and the second pulley 32, and directly below the throat plate 101.

[0058] As shown in FIG. 5, the guide frame 29 includes a bracket portion 295 for fixing the guide frame 29 within the sewing machine bed portion 111, and a cylindrical main body portion 296 for guiding each of the lower belts 21 to 24.

[0059] The guide frame 29 is arranged directly below the throat plate 101 with a central axis of the main body portion 296 oriented in the left-and-right direction.

[0060] A fitting groove 297 extending in the front-and-rear direction is formed at a center, in the left-and-right direction, of an upper portion of an outer peripheral surface of the main body portion 296. The plate-shaped eye member 30, which is elongated in the front-and-rear direction, is fixedly fitted and arranged inside the fitting groove 297. The eye member 30 is formed with an eye 13 penetrating in the up-and-down direction at a stitch point position.

[0061] A surface of the eye member 30 where the eye 13 is formed is flush with or slightly higher than an upper surface of the throat plate 101.

[0062] In addition, the main body portion 296 allows each of the lower belts 21 to 24 to circumferentially slide on the upper portion of the outer peripheral surface of the main body portion 296, thereby feeding a workpiece. To this end, a first guide portion 291, a second guide portion 292, a third guide portion 293, and a fourth guide portion 294 are provided on the upper portion of the outer peripheral surface of the main body portion 296 to respectively guide the lower belts 21 to 24.

[0063] The first guide portion 291 is provided at the left rear of the eye 13, the second guide portion 292 is provided at the left front of the eye 13, the third guide portion 293 is provided at the right front of the eye 13, and the fourth guide portion 294 is provided at the right rear of the eye 13.

[0064] Each of the guide portions 291 to 294 is a projection extending in the front-and-rear direction, and has a width in the left-and-right direction equal to or slightly greater than a width of each of the lower belts 21 to 24. A rear end portion of each of the guide portions 291 to 294 forms a slope in which an amount of protrusion radially outward from the outer peripheral surface of the main body portion 296 gradually increases toward the front. In addition, a front end portion of each of the guide portions 291 to 294 forms a slope in which an amount of protrusion radially outward from the outer peripheral surface of the main body portion 296 gradually decreases toward the front.

[0065] The first guide portion 291 is located to the left of the eye 13 and rearward of the center of the eye 13 over almost its entire length.

[0066] The first guide portion 291 has a guide surface 291a (a portion indicated by dots in FIG. 5) that is flat and horizontal forward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 291a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0067] The guide surface 291a is set such that an outer surface of the rear left lower belt 21, which passes in sliding contact on the guide surface 291a, is slightly higher than the upper surface of the throat plate 101.

[0068] The guide surface 291a is formed such that a front end portion of the guide surface 291a is located slightly rearward of the center of the eye 13, and the rear left lower belt 21 comes into contact with a workpiece rearward of the center of the eye 13.

[0069] The second guide portion 292 is located to the left of the eye 13, to the right of the first guide portion 291 and forward of the center of the eye 13 over almost its entire length.

[0070] The second guide portion 292 has a guide surface 292a (a portion indicated by dots in FIG. 5) that is flat and horizontal rearward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 292a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0071] The guide surface 292a is set such that an outer surface of the front left lower belt 22, which passes in sliding contact on the guide surface 292a, is slightly higher than the upper surface of the throat plate 101.

[0072] The guide surface 292a is formed such that a rear end portion of the guide surface 292a is located slightly forward of the center of the eye 13, and the front left lower belt 22 comes into contact with a workpiece forward of the center of the eye 13.

[0073] The third guide portion 293 is located to the right of the eye 13 and forward of the center of the eye 13 over almost its entire length.

[0074] The third guide portion 293 has a guide surface 293a (a portion indicated by dots in FIG. 5) that is flat and horizontal rearward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 293a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0075] The guide surface 293a is set such that an outer surface of the front right lower belt 23, which passes in sliding contact on the guide surface 293a, is slightly higher than the upper surface of the throat plate 101.

[0076] The guide surface 293a is formed such that a rear end portion of the guide surface 293a is located slightly forward of the center of the eye 13, and the front right lower belt 23 comes into contact with a workpiece forward of the center of the eye 13.

[0077] The fourth guide portion 294 is located to the right of the eye 13 and the third guide portion 293 and rearward of the center of the eye 13 over almost its entire length.

[0078] The fourth guide portion 294 has a guide surface 294a (a portion indicated by dots in FIG. 5) that is flat and horizontal forward of its maximum protruding portion in the radially outward direction of the main body portion 296. The guide surface 294a is arranged to face the combined opening portion 102 of the throat plate 101 when viewed from above.

[0079] The guide surface 294a is set such that an outer surface of the rear right lower belt 24, which passes in sliding contact on the guide surface 294a, is slightly higher than the upper surface of the throat plate 101.

[0080] The guide surface 294a is formed such that a front end portion of the guide surface 294a is located slightly rearward of the center of the eye 13, and the rear right lower belt 24 comes into contact with a workpiece rearward of the center of the eye 13.

[0081] The guide surfaces 291a and 294a are provided rearward of the center of the eye 13, and the guide surfaces 292a and 293a are provided forward of the center of the eye 13. For this reason, when a speed difference (difference in conveying amount) 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 respective lower belts 21 to 24 can apply a conveying force caused by the front-and-rear feed speed difference (difference in conveying amount) to the workpiece without interfering with each other. Accordingly, a seam as intended is formed during differential feed in the front-and-rear direction, making it possible to improve stitch quality.

[0082] The first pressurizing mechanism 33 applies tension to all of the belts, among the lower belts 21 to 24, wrapped between the guide frame 29 and the first pulley 31, thereby suppressing sagging.

[0083] The first pressurizing mechanism 33 includes a left pressurizing roller 331, a right pressurizing roller 332, a support plate 333, and a base block 334, as shown in FIGS. 2, 3, and 6.

[0084] The support plate 333 has an elongated flat plate shape extending in the front-and-rear and up-and-down directions, and is supported by the base block 334 with its longitudinal direction oriented obliquely upward and forward.

[0085] Additionally, the support plate 333 concentrically and rotatably supports the left pressurizing roller 331 and the right pressurizing roller 332 on left and right surfaces of an upper end portion of the support plate 333. The support plate 333 is arranged such that the left pressurizing roller 331 and the right pressurizing roller 332 come into contact with the outer surface of the belt extending between the guide frame 29 and the first pulley 31 from a lower rear side.

[0086] The base block 334 is shared with the second pressurizing mechanism 34 described below, and supports the structures of the first pressurizing mechanism 33 and the second pressurizing mechanism 34. The base block 334 is fixedly provided below the guide frame 29 within the sewing machine bed portion 111.

[0087] The support plate 333 has an elongated hole extending in the longitudinal direction of the support plate 333, and is fastened and fixed to the base block 334 by two bolts inserted into the elongated hole. The longitudinal direction of the support plate 333 is oriented in a direction approximately orthogonal to the belt that is wrapped around the first pulley 31. Accordingly, the press-contact forces of the left pressurizing roller 331 and the right pressurizing roller 332 against the belt can be adjusted by loosening the bolts and moving the support plate 333 along the elongated hole. In other words, the tension of the belt extending between the guide frame 29 and the first pulley 31 can be adjusted.

[0088] The left pressurizing roller 331 and the right pressurizing roller 332 have the same outer diameter and are supported by the support plate 333 so as to be rotatable about the same axis extending in the left-and-right direction. In addition, the left pressurizing roller 331 and the right pressurizing roller 332 each have a width in the left-and-right direction that is equal to or greater than twice a width of each of the lower belts 21 to 24.

[0089] Accordingly, the left pressurizing roller 331 can be brought into contact with either the rear left lower belt 21 or the front left lower belt 22 wrapped between the guide frame 29 and the first pulley 31.

[0090] Similarly, the right pressurizing roller 332 can be brought into contact with either the front right lower belt 23 or the rear right lower belt 24 wrapped between the guide frame 29 and the first pulley 31.

[0091] The second pressurizing mechanism 34 applies tension to all of the belts, among the lower belts 21 to 24, wrapped between the guide frame 29 and the second pulley 32, thereby suppressing sagging.

[0092] The second pressurizing mechanism 34 includes a left pressurizing roller 341, a right pressurizing roller 342, a support plate 343, and the base block 334 described above, as shown in FIGS. 2, 3, and 6.

[0093] The support plate 343 has the same structure as that of the support plate 333 described above, and is supported by the base block 334 with its longitudinal direction oriented obliquely upward and rearward.

[0094] Additionally, the support plate 343 concentrically and rotatably supports the left pressurizing roller 341 and the right pressurizing roller 342 on left and right surfaces of an upper end portion of the support plate 343. The support plate 343 is arranged such that the left pressurizing roller 341 and the right pressurizing roller 342 come into contact with the outer surface of the belt extending between the guide frame 29 and the second pulley 32 from an upper rear side.

[0095] The support plate 343 also has an elongated hole, and the support plate 343 can be moved along the elongated hole. Accordingly, the contact-press forces of the left pressurizing roller 341 and the right pressurizing roller 342 against the belt wrapped around the second pulley 32 can be adjusted. Therefore, the tension of the belt extending between the guide frame 29 and the second pulley 32 can be adjusted.

[0096] The left pressurizing roller 341 and the right pressurizing roller 342 have the same outer diameter and are supported by the support plate 343 so as to be rotatable about the same axis extending in the left-and-right direction. In addition, the left pressurizing roller 341 and the right pressurizing roller 342 each have a width in the left-and-right direction that is equal to or greater than twice a width of each of the lower belts 21 to 24.

[0097] Accordingly, the left pressurizing roller 341 can be brought into contact with either the rear left lower belt 21 or the front left lower belt 22 wrapped between the guide frame 29 and the second pulley 32.

[0098] Similarly, the right pressurizing roller 342 can be brought into contact with either the front right lower belt 23 or the rear right lower belt 24 wrapped between the guide frame 29 and the second pulley 32.

[0099] Both the left pressurizing roller 331 of the first pressurizing mechanism 33 and the left pressurizing roller 341 of the second pressurizing mechanism 34 can be brought into contact with the rear left lower belt 21 and the front left lower belt 22. Similarly, both the right pressurizing roller 332 of the first pressurizing mechanism 33 and the right pressurizing roller 342 of the second pressurizing mechanism 34 can be brought into contact with the front right lower belt 23 and the rear right lower belt 24.

[0100] Accordingly, each of the lower belts 21 to 24 is provided with tension by either the first pressurizing mechanism 33 or the second pressurizing mechanism 34, regardless of whether it is wrapped around the first pulley 31 or the second pulley 32.

[0101] FIG. 6 shows a state in which the front left lower belt 22 and the front right lower belt 23, which perform feed forward of the stitch point position, are wrapped around the first pulley 31, and the rear left lower belt 21 and the rear right lower belt 24, which perform feed rearward of the stitch point position, are wrapped around the second pulley 32.

[0102] FIG. 7 shows a state in which the rear left lower belt 21 and the front left lower belt 22, which perform feed leftward of the stitch point position, are wrapped around the first pulley 31, and the front right lower belt 23 and the rear right lower belt 24 are wrapped around the second pulley 32.

[0103] When the bolts are loosened and each of the pressurizing rollers 331, 332, 341, and 342 is retracted, each of the lower belts 21 to 24 can be easily removed from each of the pulleys 31 and 32 for replacement and rewrapping.

[0104] Accordingly, it is possible to easily select and perform sewing in the wrapping state of FIG. 6 and sewing in the wrapping state of FIG. 7.

[0105] For example, in the wrapping state of FIG. 6 (a front-and-rear differential feed state), it is possible to perform a so-called shirring stitch in which feed is performed faster on a side forward of the stitch point position than on a side rearward of the stitch point position.

[0106] In addition, in the front-and-rear differential feed state, it is also possible to perform sewing in which feed is performed slower on a side forward of the stitch point position than on a side rearward of the stitch point position and tension is applied to a workpiece.

[0107] In the wrapping state of FIG. 7 (a left-and-right differential feed state), when feed is performed faster on the left side, a curved stitch turning to the right can be performed, and when feed is performed faster on the right side, a curved stitch turning to the left can be performed.

[0108] In addition, since the curvature can be changed depending on the magnitude of the speed difference (difference in conveying amount) between the left and right sides, various curved stitches can be performed.

[0109] In the present embodiment, it is assumed that the sewing machine 100 is used in a left-and-right differential feed state. Therefore, in the following description, each of the lower belts 21 to 24 is assumed to be in the wrapping state of FIG. 7.[Cloth Presser Mechanism]

[0110] FIG. 8 is a perspective view of the cloth presser mechanism 70 as a presser mechanism for pressing a workpiece on the throat plate 101 from above, FIG. 9 is a rear view of the cloth presser mechanism 70, and FIG. 10 is an exploded perspective view of the cloth presser mechanism 70.

[0111] The cloth presser mechanism 70 includes a presser foot 71, a presser bar 72, a mounting base 74, a presser motor 73 (see FIG. 13), and a height sensor 762 (see FIG. 13).

[0112] The presser bar 72 is arranged in front of and adjacent to the needle bar 12 and is supported so as to be movable up and down within the sewing machine arm portion 113 with oriented in the up-and-down direction.

[0113] An upper end portion of the presser bar 72 is pressed downward by a presser spring (not shown) within the sewing machine arm portion 113. An amount of expansion and contraction of the presser spring can be adjusted by the presser motor 73 whose operation amount can be arbitrarily controlled. Therefore, by controlling the presser motor 73, a pressing pressure of the presser foot 71 can be arbitrarily set.

[0114] In addition, the height sensor 762 that detects a height of the presser bar 72 is provided in association with the presser bar 72. Therefore, after setting the pressing pressure of the presser foot 71 to a specified value, when the height sensor 762 detects that a height of the presser foot 71 varies due to a change in thickness of a workpiece, the pressing pressure can be maintained at a constant set value by controlling the presser motor 73 so that the amount of expansion and contraction of the presser spring does not vary.

[0115] The presser foot 71 is provided on a lower end portion of the presser bar 72 via the mounting base 74. The mounting base 74 is a block having horizontal and flat upper and lower surfaces. The mounting base 74 has an insertion hole into which the presser bar 72 can be inserted, the hole penetrating in the up-and-down direction. The mounting base 74 is formed with a slit extending from the insertion hole to an outer edge portion, and is provided with a screw 741 for fastening the slit to narrow its gap width. When the screw 741 is fastened with the lower end portion of the presser bar 72 inserted in the insertion hole, the presser bar 72 can be clamped and fixed. When the screw 741 is loosened, the mounting base 74 can be detached from the presser bar 72.

[0116] The mounting base 74 is attached to the presser bar 72 with the lower end portion of the presser bar 72 slightly protruding beyond a lower surface of the mounting base.

[0117] The lower end portion of the presser bar 72 is attached with its smooth lower surface in contact with an upper flat surface 712d of the presser foot 71.

[0118] A projection 742 that serves as a guide for attaching the upper end portion of the presser foot 71 is formed on a left side surface of the mounting base 74 along the front-and-rear direction of the mounting base 74.

[0119] In addition, a lower end portion of a link member 474 of the upper feed mechanism 40 described below is connected to a front end portion of the mounting base 74 so as to be rotatable about an axis extending along the left-and-right direction of the mounting base 74.

[0120] The presser foot 71 is arranged above the combined opening portion 102 of the throat plate 101. The presser foot 71 presses a workpiece from above to appropriately transmit a conveying force caused by each of the lower belts 21 to 24 to the workpiece. Additionally, the presser foot 71 supports a left upper belt 41 and a right upper belt 42 of the upper feed mechanism 40 so that they can be conveyed. The presser foot 71 also has a function of pressing each of the upper belts 41 and 42 against the workpiece to appropriately transmit the conveying force to the workpiece.

[0121] As shown in FIGS. 8 to 10, the presser foot 71 includes a bottom plate 711 that presses a workpiece from above, and a connecting portion 712 attached to the lower end portion of the presser bar 72.

[0122] The bottom plate 711 is formed in a so-called boat shape with a smooth bottom surface and an upstream side (rear end portion) in a cloth feeding direction curved upward.

[0123] The connecting portion 712 is erected on an upper surface of a front end portion of the bottom plate 711, and is connected to the bottom plate 711 so as to be swingable to some extent about an axis extending along the left-and-right direction. An upper portion of the connecting portion 712 is formed with a flat surface 712d in contact with the lower surface of the lower end portion of the presser bar 72. Additionally, a sidewall 712a is erected on a left end of an upper portion of the connecting portion 712. A right surface of the sidewall 712a is formed with a recessed groove 712b that faces the left side surface of the mounting base 74 and fits with the projection 742.

[0124] The connecting portion 712 is in a correct posture along the vertical up-and-down direction by bringing the flat surface of the upper portion into contact with the lower surface of the mounting base 74 and fitting the projection 742 into the recessed groove 712b.

[0125] Additionally, the sidewall 712a is formed with an insertion hole 712c for a screw 743, the insertion hole penetrating in the left-and-right direction. On the other hand, the left side surface of the mounting base 74 is formed with a screw hole 744. Accordingly, by passing the screw 743 through the insertion hole 712c and fastening it to the screw hole 744, the presser foot 71 can be fixed to the mounting base 74 in a proper position and posture. Note that by loosening the screw 743, the presser foot 71 can be detached from the mounting base 74 and the presser bar 72.[Upper Feed Mechanism]

[0126] As shown in FIGS. 1, 2, and 8 to 10, the upper feed mechanism 40 includes a left upper belt 41 and a right upper belt 42 as conveyor belts, left and right belt guides 43 and 44, a left upper motor 45 as a drive source for belt feed of the left upper belt 41, a right upper motor 46 as a drive source for belt feed of the right upper belt 42, and a guide mechanism 47 that guides each of the upper belts 41 and 42 from each of the upper motors 45 and 46 to the presser foot 71.

[0127] The left and right belt guides 43 and 44 are provided on both the left and right sides of the presser foot 71.

[0128] The respective belt guides 43 and 44 are rotatably attached to left and right side surfaces of a lower portion of the connecting portion 712 of the presser foot 71 by a support shaft 431 extending along the left-and-right direction.

[0129] Each of the belt guides 43 and 44 is configured such that, when viewed from a side, a front end portion extends obliquely upward and forward, a front side of a rear end portion is closest to the throat plate 101, and the rear end portion is raised obliquely upward and rearward. In addition, the rear end portions of the belt guides 43 and 44 are respectively provided with feed rollers 432 and 442 that are rotatable about axes extending along the left-and-right direction.

[0130] The left and right endless loop-shaped upper belts 41 and 42 are guided respectively between the belt guides 43 and 44 and the side surfaces of the presser foot 71. That is, the left upper belt 41, which is a left belt, and the right upper belt 42, which is a right belt, are respectively folded back downward from the upper sides of the feed rollers 432 and 442 along their outer peripheries, are guided to travel forward along the portions of the respective belt guides 43 and 44 that are closest to the throat plate 101, and then proceed obliquely upward and forward. When traveling forward along the portions of the respective belt guides 43 and 44 that are closest to the throat plate 101, each of the upper belts 41 and 42 comes into contact with a workpiece on the throat plate 101 and performs forward feed.

[0131] Additionally, as described above, each of the belt guides 43 and 44 is supported on the presser foot 71 by the support shaft 431. One end portion of each of tension springs 433 and 443 is connected to the front end portion of each of the belt guides 43 and 44. Each of the tension springs 433 and 443 is connected, at its other end portion, to the upper portion of the connecting portion 712 of the presser foot 71 and applies an upward tension to the front end portion of each of the belt guides 43 and 44.

[0132] Accordingly, the rear end portion side of each of the belt guides 43 and 44 is urged to rotate downward, and a contact-press force toward the throat plate 101 is applied to each of the upper belts 41 and 42 traveling forward along the portions closest to the throat plate 101.

[0133] The left and right upper motors 45 and 46 are motors whose rotation speeds can be controlled. As the upper motors 45 and 46, for example, DC motors, AC motors, stepping motors, or the like are used.

[0134] The left upper motor 45 is supported on a front side of the left end portion of the sewing machine arm portion 113 via a motor bracket 451, with its output shaft oriented leftward.

[0135] In addition, the right upper motor 46 is supported above the left upper motor 45 on the front side of the left end portion of the sewing machine arm portion 113 via the motor bracket 451, with its output shaft oriented leftward.

[0136] A motor pulley 452 is mounted on the output shaft of the left upper motor 45, and one end portion of the left upper belt 41 is wound around the motor pulley 452.

[0137] In addition, a motor pulley 462 is mounted on the output shaft of the right upper motor 46, and one end portion of the right upper belt 42 is wound around the motor pulley 462.

[0138] The left upper belt 41 has an endless loop shape, with one end portion wrapped around the motor pulley 452 of the left upper motor 45 and the other end portion wrapped around the feed roller 432 of the belt guide 43, in a stretched state.

[0139] The right upper belt 42 also has an endless loop shape, with one end portion wrapped around the motor pulley 462 of the right upper motor 46 and the other end portion wrapped around the feed roller 442 of the belt guide 44, in a stretched state.

[0140] A path in the left upper belt 41 from the motor pulley 452 to the feed roller 432 and a path in the right upper belt 42 from the motor pulley 462 to the feed roller 442 overlap each other, except for areas around the motor pulleys 452 and 462, when viewed from the left-and-right direction. Note that the right upper belt 42 is arranged on the right side relative to the left upper belt 41.

[0141] The guide mechanism 47 guides the left upper belt 41 and the right upper belt 42 along the respective paths.

[0142] The guide mechanism 47 includes a pair of first tension rollers 471 arranged side by side in the left-and-right direction, a pair of second tension rollers 472 arranged side by side in the left-and-right direction, a guide arm 475 composed of upper and lower link members 473 and 474, and a plurality of guide rollers 476 rotatably provided at each portion on the path of each of the upper belts 41 and 42.

[0143] The pair of first tension rollers 471 is arranged below the motor pulley 452. In addition, the pair of second tension rollers 472 is arranged between the motor pulley 452 and the pair of first tension rollers 471.

[0144] The pair of first tension rollers 471 is rotatable about axes extending along the left-and-right direction, and each roller has a wide axial width. The pair of first tension rollers 471 presses against both the left upper belt 41 and the right upper belt 42 from the outer sides, thereby applying inward tension thereto.

[0145] The pair of second tension rollers 472 is rotatable about axes extending along the left-and-right direction, and each roller has a wide axial width. The pair of second tension rollers 472 presses against only the right upper belt 42 from the inner side, thereby applying outward tension thereto.

[0146] In addition, since the right upper belt 42 can be widened leftward and rightward by the pair of second tension rollers 472, the right upper belt 42 can avoid interference with the motor pulley 452 in the middle of the path.

[0147] The upper link member 473 constituting the guide arm 475 has one end portion connected to a lower end portion of the motor bracket 451 so as to be rotatable about an axis extending along the left-and-right direction. Additionally, the other end portion of the upper link member 473 is connected to one end portion of the lower link member 474 so as to be rotatable about an axis extending along the left-and-right direction.

[0148] In addition, the other end portion of the lower link member 474 is connected to the front end portion of the mounting base 74 so as to be rotatable about the axis extending along the left-and-right direction, as described above.

[0149] At a connecting portion between the upper link member 473 and the lower link member 474, a guide roller 476 is provided to contact the inner side of the loop from the front side, and another guide roller (not shown) is provided to contact the outer side of the loop from the front side, with respect to the left upper belt 41 and the right upper belt 42.

[0150] Accordingly, the left and right upper belts 41 and 42 are conveyed along paths defined by the upper link member 473 and the lower link member 474.

[0151] Therefore, even when the presser foot 71 moves up and down due to changes in the thickness of the workpiece or unevenness and the bending angle between the upper link member 473 and the lower link member 474 changes, the left and right upper belts 41 and 42 still follow the paths defined by the upper link member 473 and the lower link member 474. As a result, the path length of each of the upper belts 41 and 42 is maintained constant, and variation in tension can be suppressed.[End Portion Detection Device]

[0152] FIG. 11 is a perspective view showing the periphery of the throat plate 101 provided with the end portion detection device 80, and FIG. 12 is a rear view of the throat plate 101.

[0153] As illustrated in FIGS. 11 and 12, the end portion detection device 80 includes upper end portion sensors 811 and 812 as upper detection units, lower end portion sensors 821 and 822 as lower detection units, a sensor holding frame 83, an upper guide 84 as a guide, a lower guide 85 as a guide, and a housing 86.

[0154] The housing 86 includes a rectangular top plate portion 861 and two wall portions 862 provided at front and rear end portions of the top plate portion 861. The housing 86 has open bottom and left end portions.

[0155] The housing 86 is arranged on the throat plate 101 such that the entirety thereof is positioned slightly to the right of the stitch point position in the left-and-right direction. In addition, the housing 86 is arranged on the throat plate 101 such that the entirety thereof is positioned slightly rearward (upstream in the feed direction) of the stitch point position in the front-and-rear direction.

[0156] In addition, the front-side and rear-side wall portions 862 of the housing 86 each have a lower end portion of a left end, which is cut away toward the right. The cutout is formed to avoid contact with right end portions of an upper cloth C1 and a lower cloth C2, which serve as workpieces that are fed forward during sewing.

[0157] The housing 86 supports the entire configuration of the end portion detection device 80. The housing 86 is attached to the upper surface of the sewing machine bed portion 111 in the arrangement described above.

[0158] In this case, the housing 86 may be fixed to the upper surface of the sewing machine bed portion 111 by a well-known fixing structure. As a well-known fixing structure, screw fixing or the like can be used. In addition, the entire end portion detection device 80 may be made detachable by providing a permanent magnet at a lower end portion of the housing 86. In this case, it is preferable to provide a structure in which a recess or a projection is formed on the sewing machine bed portion 111 side so as to allow positioning of the housing 86, and the lower end portion of the housing 86 is fitted to the recess or projection to enable positioning.

[0159] The sensor holding frame 83 is supported on a rear surface of the front-side wall portion 862 of the housing 86. At a left end portion of the sensor holding frame 83, an upper wall portion 831, an intermediate wall portion 833, and a lower wall portion 832 are provided side by side in this order from the top, and are formed in a comb-like shape when viewed from the front-and-rear direction. Each of the upper wall portion 831, the intermediate wall portion 833, and the lower wall portion 832 has a plate shape extending in the front-and-rear direction and the left-and-right direction. A left end portion of the upper wall portion 831, a left end portion of the intermediate wall portion 833, and a left end portion of the lower wall portion 832 each extend slightly to the left of the stitch point position.

[0160] A right side end portion of the upper cloth C1, which is fed forward by the upper feed mechanism 40, passes between the upper wall portion 831 and the intermediate wall portion 833.

[0161] Similarly, a right side end portion of the lower cloth C2, which is fed forward by the lower feed mechanism 20, passes between the lower wall portion 832 and the intermediate wall portion 833.

[0162] In order to insert the lower cloth C2 between the lower wall portion 832 and the intermediate wall portion 833, the sensor holding frame 83 is configured such that substantially the entire lower wall portion 832 is housed inside a rectangular opening portion 103 provided in the throat plate 101, and an upper surface of the lower wall portion 832 is flush with the upper surface of the throat plate 101.

[0163] Note that since it is only necessary to ensure a gap sufficient to allow insertion of the lower cloth C2 between a lower surface of the intermediate wall portion 833 and the upper surface of the throat plate 101, the upper surface of the lower wall portion 832 may be positioned lower than the upper surface of the throat plate 101.

[0164] On a lower surface of the upper wall portion 831, upper end portion sensors 811 and 812 that face downward are provided on left and right sides across a position that is located at a predetermined distance S to the right of the stitch point position. The distance S coincides with the target seam allowance of the upper cloth C1 and the lower cloth C2. The seam allowance refers to a distance from an end edge portion of a workpiece to a seam when sewing is performed along the end edge portion.

[0165] The upper end portion sensors 811 and 812 are each constituted by a so-called reflective type photo interrupter in which both a light source and a light-receiving element are oriented downward. An upper surface of the intermediate wall portion 833 is formed as a reflective surface, and the upper end portion sensors 811 and 812 are configured such that the light-receiving element can receive reflected light of the light emitted by the light source.

[0166] Detection outputs from the upper end portion sensors 811 and 812 are input to the control device 90, and the control device 90 can recognize that the right end of the upper cloth C1 is present at the detection position, based on a decrease in the amount of reflected light received.

[0167] The upper end portion sensors 811 and 812 are respectively provided slightly to the left or right of a position corresponding to the distance S. That is, the upper end portion sensors 811 and 812 define an allowable range within which the right end portion of the upper cloth C1 can be considered to be positioned at the distance S.

[0168] During sewing, the control device 90 performs control to move the upper cloth C1 rightward when the right end portion of the upper cloth C1, having entered between the upper wall portion 831 and the intermediate wall portion 833 from the left, is no longer detected by the left upper end portion sensor 811, and performs control to move the upper cloth C1 leftward when the right end portion of the upper cloth C1 is detected by the right upper end portion sensor 812. Accordingly, control is performed to maintain the right end of the upper cloth C1 between the upper end portion sensors 811 and 812 on the left and right sides.

[0169] On the upper surface of the lower wall portion 832, lower end portion sensors 821 and 822 that face upward are provided on left and right sides across a position that is located at the predetermined distance S to the right of the stitch point position.

[0170] The lower end portion sensors 821 and 822 are also each constituted by a reflective type photo interrupter. The intermediate wall portion 833 also has a lower surface formed as a reflective surface.

[0171] In the case of the lower end portion sensors 821 and 822, the control device 90 can also recognize that the right end of the lower cloth C2 is present at the detection position, based on a decrease in the amount of reflected light received.

[0172] The left-and-right arrangement of the lower end portion sensors 821 and 822 is the same as that of the upper end portion sensors 811 and 812, and defines an allowable range within which the right end portion of the lower cloth C2 can be considered to be positioned at the distance S.

[0173] During sewing, the control device 90 performs control to move the lower cloth C2 rightward when the right end portion of the lower cloth C2, having entered between the lower wall portion 832 and the intermediate wall portion 833 from the left, is no longer detected by the left lower end portion sensor 821, and performs control to move the lower cloth C2 leftward when the right end portion of the lower cloth C2 is detected by the right lower end portion sensor 822. Accordingly, control is performed to maintain the right end of the lower cloth C2 between the lower end portion sensors 821 and 822 on the left and right sides.

[0174] Note that the upper end portion sensors 811 and 812 and the lower end portion sensors 821 and 822 are not limited to the photo interrupters, and any detection means capable of detecting a cloth end can be used. For example, a microswitch or the like may be used to detect that a seam allowance exceeds the distance S when the right end portion of the upper cloth C1 or the lower cloth C2 comes into contact from the left.

[0175] Both the upper guide 84 and the lower guide 85 are plate-shaped guides.

[0176] The upper guide 84 is provided to guide the upper cloth C1 between the upper wall portion 831 and the intermediate wall portion 833 of the sensor holding frame 83.

[0177] The lower guide 85 is provided to guide the lower cloth C2 between the lower wall portion 832 and the intermediate wall portion 833 of the sensor holding frame 83. The lower guide 85 also has a function of separating the upper cloth C1 and the lower cloth C2.

[0178] The lower guide 85 extends rearward and leftward with respect to the intermediate wall portion 833. The lower guide 85 is formed to have substantially the same thickness as that of the intermediate wall portion 833. An upper surface of the lower guide 85 is supported inside the housing 86 so as to be at the same height as the upper surface of the intermediate wall portion 833, and the lower surface of the lower guide 85 is supported inside the housing 86 so as to be at the same height as the lower surface of the intermediate wall portion 833.

[0179] Additionally, rear and left extension end portions of the lower guide 85 are formed to be slightly bent or curved upward. This facilitates feed of the lower cloth C2 to the lower side of the lower guide 85 during sewing.

[0180] The upper guide 84 extends rearward and leftward from the upper wall portion 831. A lower surface of the upper guide 84 is supported inside the housing 86 so as to be at the same height as the lower surface of the upper wall portion 831.

[0181] Additionally, rear and left extension end portions of the upper guide 84 are formed to be slightly bent or curved upward. This facilitates feed of the lower cloth C2 between the upper guide 84 and the lower guide 85 during sewing.[Control System of Sewing Machine]

[0182] FIG. 13 is a block diagram showing a control system of the sewing machine 100.

[0183] As shown in FIG. 13, the sewing machine 100 includes the control device 90 that controls an operation of each configuration. The sewing machine motor 16, the presser motor 73, the first motor 25, the second motor 26, the left upper motor 45, and the right upper motor 46 are connected to the control device 90 via motor drive circuits 16a, 73a, 25a, 26a, 45a, and 46a, respectively.

[0184] In addition, the sewing machine motor 16, the presser motor 73, the first motor 25, the second motor 26, the left upper motor 45, and the right upper motor 46 are provided with encoders 161, 732, 251, 261, 451, and 461 for detecting their respective rotational speeds. The encoders 161, 732, 251, 261, 451, and 461 are also connected to the control device 90 via motor drive circuits 16a, 73a, 25a, 26a, 45a, and 46a, respectively.

[0185] The control device 90 includes a CPU 91, a ROM 92, a RAM 93, and an EEPROM (registered trademark) 94, and executes various operation controls described below.

[0186] A basic system program is stored in the ROM 92.

[0187] Additionally, various setting data, other programs, and the like are stored in the EEPROM 94. Note that the various setting data and programs may be stored in a nonvolatile memory device such as a flash memory, an EPROM, an HDD, or the like, instead of the EEPROM.

[0188] The CPU 91 executes various programs in the ROM 92 and the EEPROM 94. The RAM 93 is a memory that serves as a working area for the CPU 91.

[0189] Additionally, an operation input unit 96 is connected to the control device 90 via an interface 96a.

[0190] The operating input unit 96 includes an input screen 961. Information necessary for inputting various settings is displayed on the input screen 961.

[0191] In addition, set values of a stitch pitch, a pressing pressure during sewing by the cloth presser mechanism 70, and the like can be input from the operation input unit 96.

[0192] In addition, a pedal 95 that inputs operations such as start and stop of sewing and increase / decrease in sewing speed by a depression operation is connected to the control device 90 via an interface 95a.

[0193] In addition, the height sensor 762 that detects a height of the presser foot 71, the upper end portion sensors 811 and 812, and the lower end portion sensors 821 and 822 are connected to the control device 90 via interfaces 762a, 811a, 812a, 821a, and 822a.[Sewing Control]

[0194] Here, sewing control of a workpiece performed based on a control program 941 will be described. FIG. 14 is a flowchart showing a process that is performed by the CPU 91 executing the control program 941.

[0195] First, an operator of the sewing machine feeds the lower cloth C2 between the lower guide 85 and the throat plate 101, feeds the upper cloth C1 between the upper guide 84 and the lower guide 85, and depresses the pedal 95.

[0196] In contrast, the CPU 91 of the control device 90 waits while monitoring the depression of the pedal 95 (step S1). When the CPU 91 detects the depression of the pedal 95, the CPU reads the set value of the feed pitch in the EEPROM 94 (step S3).

[0197] Then, the CPU 91 drives the sewing machine motor 16 at a speed corresponding to the amount of depression of the pedal 95 (step S5). Additionally, the CPU 91 starts driving the left upper motor 45, the right upper motor 46, the first motor 25, and the second motor 26 at a speed at which stitch points are performed at the set feed pitch (step S7).

[0198] Accordingly, the upper cloth C1 and the lower cloth C2 are each individually fed forward.

[0199] Next, the CPU 91 determines whether the right end portion of the upper cloth C1 is detected by the left upper end portion sensor 811 (step S9). In step S9, when the right end portion of the upper cloth C1 is detected, the CPU 91 determines whether the right end portion of the upper cloth C1 is detected by the right upper end portion sensor 812 (step S10).

[0200] When the right end portion of the upper cloth C1 is also detected by the right upper end portion sensor 812, the CPU 91 determines that the upper cloth C1 is excessively shifted to the right.

[0201] Therefore, the CPU 91 executes differential feed so that the rotation speed of the right upper motor 46 becomes higher than that of the left upper motor 45, while setting the average of the rotation speeds of the left and right upper motors 45 and 46 to a rotation speed that maintains the set feed pitch (step S11). Accordingly, the upper cloth C1 is fed while being shifted to the left. Then, the CPU 91 proceeds to step S15.

[0202] In addition, in step S9, when the right end portion of the upper cloth C1 is not detected by the left upper end portion sensor 811, the CPU 91 determines that the upper cloth C1 is excessively shifted to the left.

[0203] Therefore, the CPU 91 executes differential feed so that the rotation speed of the left upper motor 45 becomes higher than that of the right upper motor 46, while setting the average of the rotation speeds of the left and right upper motors 45 and 46 to a rotation speed that maintains the set feed pitch (step S13). Accordingly, the upper cloth C1 is fed while being shifted to the right. Then, the CPU 91 proceeds to step S15.

[0204] In addition, in step S10, when the right end portion of the upper cloth C1 is not detected by the right upper end portion sensor 812, the CPU 91 determines that the right end portion of the upper cloth C1 is present at a proper position, and proceeds to step S15.

[0205] Next, the CPU 91 determines whether the right end portion of the lower cloth C2 is detected by the left lower end portion sensor 821 (step S15). In step S15, when the right end portion of the lower cloth C2 is detected, the CPU 91 determines whether the right end portion of the lower cloth C2 is detected by the right lower end portion sensor 822 (step S16).

[0206] When the right end portion of the lower cloth C2 is also detected by the right lower end portion sensor 822, the CPU 91 determines that the lower cloth C2 is excessively shifted to the right.

[0207] Therefore, the CPU 91 executes differential feed so that the rotation speed of the second motor 26 becomes higher than that of the first motor 25, while setting the average of the rotation speeds of the first and second motors 25 and 26 to a rotation speed that maintains the set feed pitch (step S17). Accordingly, the lower cloth C2 is fed while being shifted to the left. Then, the CPU 91 proceeds to step S21.

[0208] In addition, in step S15, when the right end portion of the lower cloth C2 is not detected by the left lower end portion sensor 821, the CPU 91 determines that the lower cloth C2 is excessively shifted to the left.

[0209] Therefore, the CPU 91 executes differential feed so that the rotation speed of the first motor 25 becomes higher than that of the second motor 26, while setting the average of the rotation speeds of the first and second motors 25 and 26 to a rotation speed that maintains the set feed pitch (step S19). Accordingly, the lower cloth C2 is fed while being shifted to the right. Then, the CPU 91 proceeds to step S21.

[0210] Note that the differential amounts in steps S11, S13, S17, and S19 may be arbitrarily set in advance from the operation input unit 96.

[0211] In addition, in step S16, when the right end portion of the lower cloth C2 is not detected by the right lower end portion sensor 822, the CPU 91 determines that the right end portion of the lower cloth C2 is present at a proper position, and proceeds to step S21.

[0212] Then, the CPU 91 determines whether the depression of the pedal 95 is released (step S21). In step S21, when the depression of the pedal 95 is not released, the CPU 91 returns the process to step S9 and continues the sewing while correcting the left-and-right shifts of the upper cloth C1 and the lower cloth C2 again.

[0213] In addition, when the depression of the pedal 95 is released, the CPU 91 stops driving the left upper motor 45, the right upper motor 46, the first motor 25, the second motor 26, and the sewing machine motor 16, thereby ending the sewing.[Technical Effects of Embodiment of Present Disclosure]

[0214] As described above, the sewing machine 100 is configured such that the control device 90 controls the upper feed mechanism 40 and the lower feed mechanism 20, based on detection by the end portion detection device 80, to generate a difference in the feed amount in the stitch direction between the left and right sides of the upper cloth C1 and the lower cloth C2.

[0215] Accordingly, unlike the related art in which a path is corrected by forcibly applying a feed operation in a direction orthogonal to the main feed direction, which is straight, the upper cloth C1 and the lower cloth C2 can maintain a constant seam allowance while smoothly changing path.

[0216] As a result, high-quality stitching can be achieved even when performing curved sewing.

[0217] In addition, the lower feed mechanism 20 includes the rear left lower belt 21 and the front left lower belt 22 as left belts, and the front right lower belt 23 and the rear right lower belt 24 as right belts, thereby enabling belt feed. Accordingly, unlike a case where the feeding dots are pressed, even when the lower cloth C2 is a relatively thin or delicate fabric, it is possible to feed the lower cloth properly while protecting the lower cloth.

[0218] In addition, the upper feed mechanism 40 includes the left upper belt 41 as a left upper belt and the right upper belt 42 as a right belt, thereby enabling belt feed. Accordingly, unlike a case where the feeding dots are pressed, even when the upper cloth C1 is a relatively thin or delicate fabric, it is possible to feed the upper cloth properly while protecting the upper cloth.

[0219] In addition, the end portion detection device 80 includes the upper end portion sensors 811 and 812 that detect an end portion of the upper cloth C1 overlapped on the upper side, and the lower end portion sensors 821 and 822 that detect an end portion of the lower cloth C2 overlapped on the lower side.

[0220] Therefore, the end portion detection device 80 can individually detect the end portion positions of the upper cloth C1 and the lower cloth C2, allowing the paths of the upper and lower cloths to be corrected independently and their seam allowances to be maintained constant.

[0221] As a result, even when the side end portions of the upper cloth C1 and the lower cloth C2 have different shapes, high-quality stitching can be achieved.

[0222] In addition, the end portion detection device 80 includes the lower guide 85 that separates the lower cloth C2 and the upper cloth C1, on the upstream side in the feed direction with respect to the upper end portion sensors 811 and 812 and the lower end portion sensors 821 and 822. Accordingly, since the side end portions of the lower cloth C2 and the upper cloth C1 do not interfere with each other and can be individually detected, the accuracy of end portion detection is improved, and it becomes possible to perform sewing in which the seam allowances of the lower cloth C2 and the upper cloth C1 are precisely and independently maintained constant. As a result, higher-quality stitching can be achieved.

[0223] In addition, the lower guide 85 can suppress the lower cloth C2 and the upper cloth C1 from sliding due to contact and dragging each other. Additionally, since the side end portions of the lower cloth C2 and the upper cloth C1 are accurately positioned in the left-and-right direction, the cloths can be sewn favorably together even when the shapes of the side end portions are different, and higher-quality stitching can be achieved.[Other Forms of End Portion Detection Device]

[0224] The end portion detection device 80 is not limited to the configuration described above.

[0225] For example, instead of the upper end portion sensors 811 and 812 and the lower end portion sensors 821 and 822 provided on the sensor holding frame 83, three or more upper end portion sensors 81 and lower end portion sensors 82 arranged at equal intervals in the left-and-right direction may be used as shown in FIG. 15.

[0226] In this case, when the upper end portion sensors 81 and the lower end portion sensors 82 are composed of an odd number of sensors, the sensors are arranged such that a sensor located at the center in the left-and-right direction is present at the target seam allowance position (position at the distance s). In addition, when the upper end portion sensors 81 and the lower end portion sensors 82 are composed of an even number of sensors, the sensors are arranged such that an equal number of sensors are aligned on both the left and right sides of a sensor located at the center in the left-and-right direction, which corresponds to the target seam allowance position (position at the distance S).

[0227] The control device 90 preferably performs control on the left upper motor 45 and the right upper motor 46 such that, when the cloth end of the upper cloth C1 or the lower cloth C2 is significantly shifted from the target cloth end position of the seam allowance, the amount of differential feed between the left and right sides is increased, and when the shift is small, the amount of differential feed is decreased.

[0228] Note that, instead of the plurality of upper end portion sensors 81 or lower end portion sensors 82 arranged in the left-and-right direction, a linear light-receiving sensor having a plurality of light-receiving elements as detection units arranged in the left-and-right direction may be used.

[0229] In addition, among the plurality of upper end portion sensors 81 and lower end portion sensors 82 arranged in the left-and-right direction, one of each may be selectively used to perform sewing using the position of the selected sensor as the seam allowance. In this case, sewing with multiple seam allowance widths can be performed based on the arrangement of the plurality of upper end portion sensors 81 and lower end portion sensors 82 arranged in the left-and-right direction.

[0230] Alternatively, two adjacent sensors may be selectively used among the upper end portion sensors 81 and the lower end portion sensors 82 arranged in the left-and-right direction, and sewing may be performed using the intermediate position between the two selected sensors as the seam allowance. Also in this case, sewing with multiple seam allowance widths can be performed based on the arrangement of the plurality of upper end portion sensors 81 and lower end portion sensors 82 arranged in the left-and-right direction.

[0231] In addition, when the above-described linear light-receiving sensor is used, it is possible to set the seam allowance with higher resolution and to perform sewing accordingly.

[0232] Additionally, the upper end portion sensor 81 and the lower end portion sensor 82 may be provided in plurality in the feed direction. In this case, by identifying in advance the positions of the upper cloth C1 and the lower cloth C2 upstream in the feed direction, the differential feed effect can be moderated, which makes it possible to prevent stitch line wavering and wrinkling of the upper cloth C1 and the lower cloth C2.

[0233] In addition, the end portion detection device 80 may be configured to be mounted on the upper surface of the sewing machine bed portion 111 such that its position can be adjusted in the left-and-right direction. For example, when the housing 86 is installed on the upper surface of the sewing machine bed portion 111, a plurality of positioning holes or a plurality of positioning recesses arranged in the left-and-right direction may be provided in one of the housing 86 or the sewing machine bed portion 111, and a pin insertable into the positioning holes or a projection fittable into the positioning recesses may be provided in the other. Accordingly, by selecting one of the plurality of positioning holes or the plurality of positioning recesses and fitting the pin or projection therein, the end portion detection device 80 can be arranged at a selected one of a plurality of positions in the left-and-right direction.

[0234] By selecting any desired arrangement in the left-and-right direction, it becomes possible to perform sewing with a seam allowance of any desired width.

[0235] In addition, the end portion detection device 80 may be provided on the upper surface of the sewing machine bed portion 111 so as to be movable in the left-and-right direction, and may be configured to be arbitrarily positioned in the left-and-right direction by a position adjustment mechanism including a motor whose amount of operation can be controlled. In this case, it is preferable that any value of a seam allowance can be set via the operation input unit 96, and that the control device 90 perform operation control to position the end portion detection device 80 in the left-and-right direction by the motor, in accordance with the set value of the seam allowance.

[0236] In addition, the end portion detection device 80 is fixedly mounted on the upper surface of the sewing machine bed portion 111, and the housing 86 supports the sensor holding frame 83 so as to be movable in the left-and-right direction. Furthermore, the sensor holding frame 83 may be configured to be arbitrarily positioned in the left-and-right directions by a motor whose amount of operation can be controlled.

[0237] In addition, although the configuration in which the upper cloth C1 and the lower cloth C2 are sewn with the same seam allowance dimension has been exemplified, sewing may instead be performed with different seam allowance dimensions for the upper cloth C1 and the lower cloth C2 by changing the sensor positions in the up-and-down direction. Furthermore, as described above, when the sensor positions are made movable in the left-and-right directions, it is preferable to allow the sensor positions on the upper and lower sides to be independently movable.[Mounting Example of Air Supply Device]

[0238] FIG. 16 is a perspective view illustrating an example in which a plurality of air outlets 104 are provided in an upper surface (a conveying surface for a workpiece) of the sewing machine bed portion 111 continuous with the throat plate 101, and an air supply device is provided to supply air from each of the air outlets 104.

[0239] In this case, the configuration includes an air source such as a fan or a high-pressure air tank that supplies air at a pressure higher than atmospheric pressure, a conduit that connects the air source to each of the air outlets 104, an electromagnetic valve capable of switching between connection and disconnection between each air outlet 104 and the air source, and the like. The control device 90 controls the electromagnetic valve during sewing to eject air from each outlet 104.

[0240] Accordingly, air is introduced between the lower cloth C2 and upper cloth C1 and the upper surfaces of the throat plate 101 and the sewing machine bed portion 111, thereby reducing sliding friction therebetween and allowing smooth feed and direction correction of the lower cloth C2 and the upper cloth C1.

[0241] Accordingly, the feed direction can be favorably corrected, and the seam allowance can be stably maintained at a target value, thereby enabling higher-quality stitching.[Others]

[0242] Each embodiment of the present disclosure has been described. However, the present disclosure is not limited to the above embodiments. For example, in the above embodiments, a component integrally formed by a single member may be replaced with a component divided into a plurality of members and connected or fixed to each other. Additionally, a component formed by connecting a plurality of members may be replaced with a component formed integrally by a single member. In addition, the details described in the embodiments may be appropriately changed without departing from the spirit of the invention.

[0243] In addition, although the sewing machine 100 has been exemplified as having the configuration including both the upper feed mechanism 40 and the lower feed mechanism 20, only one of the mechanisms may be provided. In this case, when the shapes of the side end portions of the upper cloth C1 and the lower cloth C2 are different, it is difficult to perform sewing. However, when the shapes of the side end portions match, it is possible to perform sewing in which the seam allowance can be maintained at a target value.

[0244] In addition, the sewing machine 100 may be configured to include the upper feed mechanism 40 and a lower feed mechanism of the related art using feeding dots that does not perform differential feed. In addition, the sewing machine 100 may be configured to include the lower feed mechanism 20 and an upper feed mechanism of the related art with feed feet that performs feed from above without performing differential feed.

[0245] In addition, as in each of the above examples, when left-and-right differential feed is performed by only one of the upper or lower mechanisms, the end portion detection device may be configured to detect a side end portion of any one of the upper cloth C1 and the lower cloth C2 without separating the cloths.

[0246] In addition, although the configuration in which belt feed is performed as the lower feed mechanism 20 has been exemplified, no such limitation is intended. For example, feeding dots for which the control device 90 can perform control to change the feed pitch independently on the left and right sides may be arranged on both left and right sides of the stitch point position of the stitch needle 11, and left-and-right differential feed may be performed by the feeding dots on the left and right sides.

[0247] In addition, although the configuration in which belt feed is performed as the upper feed mechanism 40 has been exemplified, no such limitation is intended. For example, feed feet for which the control device 90 can perform control to change the feed pitch independently on the left and right sides may be arranged on both left and right sides of the stitch needle 11, and left-and-right differential feed may be performed by the feed feet on the left and right sides.

[0248] Additionally, a belt feed mechanism of the related art may be used instead of the configuration in which the presser foot 71 can be detached from the mounting base 74 and the presser bar 72.

[0249] The present application is based on Japanese Patent Application No. 2023-056875 filed on March 31, 2023, the contents of which are incorporated herein by reference.

Examples

Embodiment Construction

[Schematic Configuration of Embodiment]

[0009]Hereinafter, a sewing machine, which is an embodiment of the present disclosure, will be described in detail.

[0010]FIG. 1 shows a rear view of a sewing machine 100, FIG. 2 shows a left side view of the sewing machine 100, and FIG. 3 shows a perspective view of the sewing machine 100.

[0011]Hereinafter, the downstream side of the feed direction of the workpiece is referred to as "front", the upstream side of the feed direction is referred to as "rear", the left side when facing forward is referred to as "left", the right side is referred to as "right", the vertically upward direction is referred to as "up", and the vertically downward direction is referred to as "down". The front-and-rear, left-and-right, and up-and-down directions are orthogonal to each other.

[0012]In the following description, it is assumed that the sewing machine 100 is installed on a horizontal plane, and the front-and-rear and left-and-right directions are horizontal.

[...

Claims

1. A sewing machine comprising: a feed mechanism configured to feed a workpiece on a throat plate in a stitch direction; and an end portion detection device configured to detect an end portion of the workpiece in a direction orthogonal to the stitch direction, wherein the feed mechanism enables differential feed, creating a variance in feed amount in the stitch direction between the left and right sides of the stitch point position, and the sewing machine comprises a control device configured to control the difference in feed amount in the stitch direction between the left and right sides by the feed mechanism, based on detection by the end portion detection device.

2. The sewing machine according to claim 1, wherein the feed mechanism comprises a lower feed mechanism configured to feed the workpiece on the throat plate from below by a conveyor belt, and the conveyor belt of the lower feed mechanism comprises a left belt configured to perform feed on the left side of the stitch point position and a right belt configured to perform feed on the right side of the stitch point position.

3. The sewing machine according to claim 1, wherein the feed mechanism comprises an upper feed mechanism configured to feed the workpiece on the throat plate from above by a conveyor belt, and the conveyor belt of the upper feed mechanism comprises a left belt configured to perform feed on the left side of the stitch point position and a right belt configured to perform feed on the right side of the stitch point position.

4. The sewing machine according to claim 2, wherein the feed mechanism comprises an upper feed mechanism configured to feed the workpiece on the throat plate from above by a conveyor belt, and the conveyor belt of the upper feed mechanism comprises a left belt configured to perform feed on the left side of the stitch point position and a right belt configured to perform feed on the right side of the stitch point position.

5. The sewing machine according to claim 4, wherein the workpiece is configured by overlapping an upper workpiece and a lower workpiece, and the end portion detection device comprises an upper detection unit configured to detect the end portion of the upper workpiece, and a lower detection unit configured to detect the end portion of the lower workpiece.

6. The sewing machine according to claim 5, comprising a guide configured to separate the lower workpiece and the upper workpiece on an upstream side in a feed direction with respect to the upper detection unit and the lower detection unit.

7. The sewing machine according to claim 1, comprising a position adjustment mechanism configured to move the end portion detection device in a direction orthogonal to the stitch direction.

8. The sewing machine according to claim 1, wherein the end portion detection device comprises a plurality of detection units arranged in a direction orthogonal to the stitch direction.

9. The sewing machine according to claim 1, comprising an air supply device configured to discharge air from an outlet provided in the throat plate or a conveying surface for the workpiece continuous with the throat plate.

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