Sewing machine

Abstract

A sewing machine (100) includes an upper feed mechanism (40) that feeds a workpiece from above a throat plate (101) by conveyor belts (41 and 42), and a presser mechanism (70) including a presser foot (71) provided with feed rollers (432 and 442) for the conveyor belts (41 and 42) and a presser bar (72) supporting the presser foot (71) at a lower end portion. The presser foot (71) is detachable from the presser bar (72), and the sewing machine includes an attachment structure (80) that allows a presser foot (8 1), which is not provided with the feed rollers (432 and 442) for the conveyor belts (41 and 42) and is not compatible with belt feed, to be attached to a lower portion of the presser bar (72).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a sewing machine that performs belt feed.BACKGROUND ART

[0002] There is a sewing machine that is provided with an upper feed mechanism, which performs feed by bringing a belt into contact with a workpiece from above a throat plate, and that performs feed individually for a lower workpiece and an upper workpiece (see, for example, Patent Literature 1).CITATION LISTPATENT LITERATURE

[0003] Patent Literature 1: JP2017-221644ASUMMARY OF INVENTIONTECHNICAL PROBLEM

[0004] A sewing machine provided with an upper feed mechanism using a belt has the advantages in that the belt does not damage a workpiece and the feed speed can be varied on upper and lower sides. Note that it is necessary to adopt a unique structure, such as providing a presser foot with a roller for belt feed.

[0005] The presser foot has been replaced with one having a specific structure corresponding to each type of sewing, so as to accommodate various types of sewing.

[0006] However, since the sewing machine provided with the upper feed mechanism using a belt has an attached presser foot specific to belt feed, the sewing machine cannot use a feed foot corresponding to various types of sewing, resulting in a decrease in versatility.

[0007] An object of the present disclosure is to improve versatility of a sewing machine.SOLUTION TO PROBLEM

[0008] The present disclosure provides a sewing machine including: an upper feed mechanism configured to feed a workpiece from above a throat plate by a conveyor belt, and a presser mechanism including a presser foot provided with a feed roller for the conveyor belt and a presser bar supporting the presser foot at a lower end portion, in which the presser foot is detachable from the presser bar, and the sewing machine includes an attachment structure configured to allow a presser foot, which is not provided with the feed roller for the conveyor belt and is not compatible with belt feed, to be attached to a lower portion of the presser bar. ADVANTAGEOUS EFFECTS OF INVENTION

[0009] The sewing machine of the present disclosure can improve versatility by the above configuration.BRIEF DESCRIPTION OF DRAWINGS

[0010] [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 of an attachment structure and a presser foot not compatible with belt feed. [FIG. 12] FIG. 12 is an exploded perspective view of the attachment structure and the presser foot not compatible with belt feed. [FIG. 13] FIG. 13 is a perspective view of another attachment structure and the presser foot not compatible with belt feed. [FIG. 14] FIG. 14 is an exploded perspective view of another attachment structure and the presser foot not compatible with belt feed. [FIG. 15A] FIG. 15A is a perspective view of another example of the presser foot not compatible with belt feed. [FIG. 15B] FIG. 15B is a perspective view of another example of the presser foot not compatible with belt feed. [FIG. 15C] FIG. 15C is a perspective view of another example of the presser foot not compatible with belt feed. [FIG. 15D] FIG. 15D is a perspective view of another example of the presser foot not compatible with belt feed. [FIG. 16A] FIG. 16A is a perspective view of another example of the presser foot not compatible with belt feed. [FIG. 16B] FIG. 16B is a perspective view of another example of the presser foot not compatible with belt feed. [FIG. 16C] FIG. 16C is a perspective view of another example of the presser foot not compatible with belt feed. DESCRIPTION OF EMBODIMENTS[Schematic Configuration of Embodiment]

[0011] Hereinafter, a sewing machine, which is an embodiment of the present disclosure, will be described in detail.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] As the sewing machine 100, which is an embodiment of the present disclosure, a so-called lockstitch sewing machine is exemplified.

[0016] The sewing machine 100 includes a sewing machine frame 110, a needle up-and-down movement mechanism, a lower feed mechanism 20, an upper feed mechanism 40, a cloth presser mechanism 70 as a presser mechanism, and a shuttle mechanism.

[0017] The needle up-and-down movement mechanism applies an up-and-down movement to a stitch needle 11.

[0018] The lower feed mechanism 20 applies a feed movement from below to a workpiece on a throat plate 101.

[0019] The upper feed mechanism 40 applies a feed movement from above to the workpiece on the throat plate 101.

[0020] The cloth presser mechanism 70 applies pressing pressure to the workpiece on the throat plate 101.

[0021] 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.

[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, a front left lower belt 22, a front right lower belt 23, and a rear right lower belt 24 of the lower feed mechanism 20 described below 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-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 15.

[0038] The outer shuttle 14 is connected to a left end portion of the shuttle shaft and rotates around the inner shuttle 15. 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 within 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, stepping motors or servo motors. Both the first motor 25 and the second motor 26 are arranged on an inner side of 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. That is, the first pulley 31 and the second pulley 32 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 its outer peripheral surface, 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. A width in the left-and-right direction of each of the guide portions 291 to 294 is 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.[Cloth Presser Mechanism]

[0109] 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.

[0110] The cloth presser mechanism 70 includes a presser foot 71, a presser bar 72, a mounting base 74, a presser motor (not shown), and a presser height detection unit (not shown).

[0111] 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.

[0112] 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 whose operation amount can be arbitrarily controlled. Therefore, by controlling the presser motor, a pressing pressure of the presser foot 71 can be arbitrarily set.

[0113] In addition, the presser height detection unit (not shown) 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 a height of the presser foot 71 changes 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 so that the amount of expansion and contraction of the presser spring does not change.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 in the left-and-right direction of the mounting base 74.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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 in 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.

[0123] The connecting portion 712 is in a correct posture along the vertical up-and-down direction by bringing the flat surface 712d of the upper portion into contact with the lower end surface of the presser bar 72 and fitting the projection 742 into the recessed groove 712b.

[0124] 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]

[0125] 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, the left and right belt guides 43 and 44 described above, 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.

[0126] The left and right belt guides 43 and 44 are provided on both the left and right sides of the presser foot 71.

[0127] 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 in the left-and-right direction.

[0128] 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 in the left-and-right direction.

[0129] 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 and right upper belts 41 and 42 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.

[0130] 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 as springs 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.

[0131] 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. As a result, a contact-press force toward a workpiece on the throat plate 101 is applied to each of the upper belts 41 and 42.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] The guide mechanism 47 guides the left upper belt 41 and the right upper belt 42 along the respective paths.

[0141] 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.

[0142] 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.

[0143] The pair of first tension rollers 471 is rotatable about axes extending in 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.

[0144] The pair of second tension rollers 472 is rotatable about axes extending in 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.

[0145] 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.

[0146] 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 in 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 in the left-and-right direction.

[0147] 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 in the left-and-right direction, as described above.

[0148] 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.

[0149] 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.

[0150] 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.[Attachment Structure For Presser Foot]

[0151] As described above, the presser foot 71 is a presser foot compatible with belt feed of the upper feed mechanism 40, and can be detached from the lower end portion of the presser bar 72.

[0152] In addition, the sewing machine 100 includes an attachment structure 80 that allows attachment of a presser foot 81 to the lower end portion of the presser bar 72. The presser foot 81 is a presser foot that is not compatible with belt feed of the upper feed mechanism 40, and is a presser foot that is not compatible with belt feed.

[0153] FIG. 11 is a perspective view of the attachment structure 80 and the presser foot 81 not compatible with belt feed, and FIG. 12 is an exploded perspective view of the attachment structure 80 and the presser foot 81 not compatible with belt feed.

[0154] The presser foot 81 not compatible with belt feed differs from the presser foot 71, and is not provided with the belt guides 43 and 44 and the feed rollers 432 and 442. The presser foot 81 has only a function of pressing a workpiece on the throat plate 101 from above.

[0155] The presser foot 81 not compatible with belt feed includes a bottom plate 811 that presses a workpiece from above, and a connecting portion 812 erected from the bottom plate 811.

[0156] The bottom plate 811 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. Since the bottom plate 811 does not require a structure to convey the left and right upper belts 41 and 42, its width in the left-and-right direction is overall greater than that of the bottom plate 711. The bottom plate 811 is arranged above the combined opening portion 102 of the throat plate 101. Additionally, the bottom plate 811 has a width that allows contact with all of the lower belts 21 to 24.

[0157] The connecting portion 812 is erected on an upper surface of a front end portion of the bottom plate 811, and is connected at its lower end portion to the bottom plate 811 so as to be swingable to some extent about an axis extending in the left-and-right direction.

[0158] A right surface of an upper portion of the connecting portion 812 is formed with a recessed groove 812a having a rectangular cross section recessed to the left, the recessed groove being open upward. Additionally, an upper end portion of a left surface of the upper portion of the connecting portion 812 is formed with a U-shaped cutout 812b.

[0159] The recessed groove 812a has a structure that allows a downward extension 821 of a joint member 82 of the attachment structure 80 described below to be fitted from above or from the right side.

[0160] In addition, the cutout 812b has a structure that allows an attachment screw 83 described below, which can be fastened to a screw hole 821a provided in the downward extension 821, to pass therethrough. Note that, instead of the cutout 812b, a through hole may be provided to allow the attachment screw 83 to pass therethrough. However, when the U-shaped cutout 812b is provided, the connecting portion 812 can be attached by inserting the downward extension 821 into the recessed groove 812a from above, with the attachment screw 83 being previously loosened and screwed into the screw hole 821a of the downward extension 821, which improves the workability of attachment. The screw hole 821a and the attachment screw 83 are each an example of a connecting portion.

[0161] In addition, the U-shaped cutout 812b is butted against the attachment screw 83 from below and also has a positioning function for attaching the presser foot 81 to the joint member 82 at a predetermined height.

[0162] Note that the presser foot 81 configured as described above is a highly versatile presser foot that can be attached to a lower end portion of a presser bar of various types of sewing machines, such as a widely distributed general lockstitch sewing machine, without being limited to the sewing machine 100. However, as described below, if the connection structure with the presser bar 72 is consistent, various presser feet suitable for different applications can be used.

[0163] The attachment structure 80 includes the mounting base 74 described above and the joint member 82.

[0164] An upper portion of the joint member 82 is formed with a flat surface 826 in contact with the lower surface of the lower end portion of the presser bar 72. Additionally, a sidewall 822 is erected on a left end of the upper portion of the joint member 82. A right surface of the sidewall 822 faces the left side surface of the mounting base 74 and is in contact with the projection 742.

[0165] The joint member 82 is in a correct posture by bringing the flat surface 826 of the upper portion into contact with the lower surface of the lower end portion of the presser bar 72 and bringing the projection 742 into contact with the sidewall 822.

[0166] Note that the sidewall 822 may be formed with a recessed groove 712b that fits with the projection 742, as with the presser foot 71.

[0167] Additionally, the sidewall 822 is formed with an insertion hole 824 for a screw 743, the insertion hole penetrating in the left-and-right direction. Accordingly, by passing the screw 743 through the insertion hole 824 and fastening it to the screw hole 744, the joint member 82 can be fixed to the mounting base 74 in a proper position and posture. Note that by loosening the screw 743, the joint member 82 can be detached from the mounting base 74.

[0168] A lower portion of the joint member 82 is provided with a downward extension 821 extending downward. The downward extension 821 is a shaft-like body having a rectangular cross section. As described above, the downward extension 821 is structured to be fittable into the recessed groove 812a of the presser foot 81 from above or from the right side. Although the downward extension 821 is exemplified as having a rectangular horizontal cross section, it is not limited thereto and may have any horizontal cross-sectional shape as long as it can be fitted into the recessed groove 812a from above or from the right side. For example, the left half of the horizontal cross section may be formed in a rectangular shape, and the right half may be formed in a semicircular or polygonal shape.

[0169] In addition, the cross-sectional shape of the recessed groove 812a and the cross-sectional shape of the left half of the downward extension 821 are not limited to rectangular shapes, and may be formed in trapezoidal or other polygonal shapes, for example.

[0170] As described above, the screw hole 821a into which the attachment screw 83 fastening and fixing the presser foot 81 is screwed is formed in a left flat surface of the downward extension 821 (a surface facing the recessed groove 812a).

[0171] Here, with the presser foot 71 attached to the mounting base 74, a height from the bottom surface of the presser bar 72 to the throat plate 101 or the bottom surface of the bottom plate 711 in contact with each of the lower belts 21 to 24 is designated as h (see FIG. 9).

[0172] With the presser foot 81 attached to the mounting base 74, a height from the bottom surface of the presser bar 72 to the throat plate 101 or the bottom surface of the bottom plate 811 in contact with each of the lower belts 21 to 24 is set to be the same as the height h.

[0173] Accordingly, in a state in which the presser bar 72 is adjusted to an appropriate height with the presser foot 71 mounted, when the presser foot 71 is replaced with the presser foot 81, it is possible to eliminate the need to readjust the height of the presser bar 72. As a result, the burden of the replacement operation from the presser foot 71 to the presser foot 81 can be reduced.[Use of Sewing Machine]

[0174] The sewing machine 100 configured as described above can perform sewing in which upper belt feed and lower belt feed are performed, with the presser foot 71 attached to the mounting base 74.

[0175] In this case, the lower feed mechanism 20 can perform sewing in which feed is performed at different speeds between the front and rear sides of the eye 13 by wrapping each of the lower belts 21 to 24, as shown in FIG. 6.

[0176] In addition, the lower feed mechanism 20 can perform sewing in which feed is performed at different speeds between the left and right sides of the eye 13 by wrapping each of the lower belts 21 to 24, as shown in FIG. 7.

[0177] In addition, since upper feed can be performed by the upper feed mechanism 40 with the presser foot 71 attached to the mounting base 74, sewing can be performed in which feed is performed at different speeds between the left and right sides of the eye 13 for an upper workpiece (referred to as an upper cloth) among vertically stacked workpieces.

[0178] In addition, when performing sewing in which the lower feed mechanism 20 performs feed at different speeds between the left and right sides of the eye 13, sewing is performed in which the upper feed mechanism 40 is also allowed to perform feed at different speeds between the left and right sides, so that the workpiece can be sewn along a curve. Additionally, when the shapes of the stitch end portions of the upper and lower workpieces are different, the upper and lower workpieces are fed along different curves, thereby allowing them to be stitched together.

[0179] On the other hand, when the upper feed is not necessary, the screw 743 is loosened to detach the presser foot 71 from the mounting base 74 and the presser foot 71 is replaced with the presser foot 81.

[0180] When attaching the presser foot 81, the joint member 82 is attached to the lower side of the mounting base 74 by the screw 743 in an appropriate orientation and position.

[0181] Additionally, the presser foot 81 is attached to the downward extension 821 of the joint member 82 by the attachment screw 83.

[0182] Note that after connecting the joint member 82 and the presser foot 81 by the attachment screw 83, the joint member 82 may be fixed to the mounting base 74.

[0183] The presser foot 71 detached for attachment of the presser foot 81 may be housed separately from the sewing machine 100 with the upper belts 41 and 42 removed from the feed rollers 432 and 442. Additionally, the presser foot 71 may be retracted to a location where it does not interfere with the sewing operation, without removing each of the upper belts 41 and 42.

[0184] In addition, it is preferable that the upper feed mechanism 40 be kept in a stationary state, in which each of the upper motors 45 and 46 is not driven, by a control device (not shown). Additionally, if a power supply for only the upper feed mechanism 40 can be turned off, the power supply may be turned off.

[0185] The sewing machine 100 with the presser foot 81 attached performs sewing using only lower feed, without performing upper feed. Also in this case, sewing using differential feed on the front and rear sides of the eye 13 or sewing using differential feed on the left and right sides of the eye 13 may be performed by the lower feed mechanism 20.[Technical Effects of Embodiment of Present Disclosure]

[0186] The sewing machine 100 includes the attachment structure 80. The attachment structure 80 allows detachment of the presser foot 71 compatible with belt feed from the presser bar 72 and attachment of the presser foot 81 not compatible with belt feed to the lower portion of the presser bar 72.

[0187] Accordingly, it becomes possible to attach and use a wide variety of presser feet, and the sewing machine 100 becomes compatible with sewing other than sewing using upper and lower belt feeds, and versatility can be improved.

[0188] In addition, since the attachment structure 80 includes the mounting base 74 and the joint member 82, even when the mounting base 74 has a structure suitable for attachment of the presser foot 71 compatible with belt feed, the presser foot 81 not compatible with belt feed can be attached to the mounting base 74 by using the joint member 82. In addition, the replacement work of the presser feet 71 and 81 becomes easier.

[0189] In addition, the attachment structure 80 has the downward extension 821 that can fit into the upper end portion of the presser foot 81 not compatible with belt feed. The downward extension 821 has the screw hole 821a for the attachment screw 83 for fastening the presser foot 81 not compatible with belt feed.

[0190] Accordingly, any presser foot having a structure (e.g., the recessed groove 812a) into which the downward extension 821 can fit and a structure (e.g., the cutout 812b) through which the attachment screw 83 can be passed can be attached to and used with the sewing machine 100.

[0191] In addition, since the attachment structure 80 includes the joint member 82 having the downward extension 821, the presser foot 81 not compatible with belt feed can be attached to the sewing machine 100 that originally does not have a configuration corresponding to the downward extension 821.

[0192] Accordingly, it becomes possible to attach the presser foot 81 not compatible with belt feed to all existing sewing machines that perform upper and lower belt feeds, thereby improving versatility.

[0193] In addition, in the attachment structure 80, the height from the bottom of the presser foot 71 to the lower end portion of the presser bar 72 when the presser foot 71 provided with the feed rollers 432 and 442 for the left and right upper belts 41 and 42 is attached matches the height from the bottom of the presser foot 81 to the lower end portion of the presser bar 72 when the presser foot 81 not compatible with belt feed is attached.

[0194] Accordingly, if the height adjustment for the presser foot 71 is completed, readjustment becomes unnecessary after attachment of the presser foot 81, and the burden of attachment work of the presser foot 81 can be reduced.

[0195] In addition, the presser foot 71 compatible with belt feed includes the belt guides 43 and 44 supported by the support shaft 431, and the tension springs 433 and 443 that apply the contact-press forces toward the workpiece on the throat plate 101 to the upper belts 41 and 42 conveyed by the belt guides 43 and 44. Therefore, the belt feed by the upper feed mechanism 40 can be performed smoothly and properly, and the stitch quality can be improved.[Examples of Other Attachment Structures]

[0196] FIG. 13 is a perspective view of another attachment structure 80A and the presser foot 81 not compatible with belt feed, and FIG. 14 is an exploded perspective view of the attachment structure 80A and the presser foot 81 not compatible with belt feed.

[0197] The attachment structure 80A includes a joint member 82A different from the joint member 82 described above.

[0198] Corresponding to the joint member 82A, a screw hole (not shown) extending vertically upward is formed in the lower surface of the lower end portion of the presser bar 72.

[0199] The joint member 82A is formed, at its upper portion, with a screw shaft 822A extending vertically upward and having a male screw that can be screwed into the screw hole formed in the presser bar 72.

[0200] Additionally, the joint member 82A is formed, at its lower portion, with the same downward extension 821 as that of the joint member 82.

[0201] Accordingly, the joint member 82A can be attached to the lower portion of the presser bar 72 by screwing the screw shaft 822A into the screw hole. Additionally, since the joint member has the downward extension 821, the presser foot 81 can be attached to the lower side, as with the joint member 82.[Various Other Presser Feet]

[0202] The presser foot not compatible with belt feed is not limited to the presser foot 81 described above, and any type of presser foot having a configuration that functions equivalently to the recessed groove 812a and the cutout 812b, which form the connection structure with the downward extension 821, can be attached to and used with the sewing machine 100.

[0203] Below, various presser feet will be described based on FIGS. 15A to 16C.

[0204] The presser foot 81 not compatible with belt feed shown in FIG. 15A includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0205] The bottom plate 811 has a left-side bottom surface higher than a right-side bottom surface, with a stitch point portion 811 a, which is formed as a cutout where stitch points are performed, serving as a boundary.

[0206] FIG. 15A is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81 that has a bottom plate 811 with a different width in the left-and-right direction, a different length in the front-and-rear direction, or a different height difference between the left-side bottom surface and the right-side bottom surface.

[0207] The presser foot 81 not compatible with belt feed shown in FIG. 15B includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0208] The bottom plate 811 has a right-side bottom surface higher than a left-side bottom surface, with a stitch point portion 811 a, which is formed as a cutout where stitch points are performed, serving as a boundary.

[0209] FIG. 15B is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81 that has a bottom plate 811 with a different width in the left-and-right direction, a different length in the front-and-rear direction, or a different height difference between the left-side bottom surface and the right-side bottom surface.

[0210] The presser foot 81 not compatible with belt feed shown in FIG. 15C includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0211] The bottom plate 811 is composed only of the right-side portion of the stitch point portion 811a where stitch points are performed.

[0212] FIG. 15C is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81 that has a bottom plate 811 with a different width in the left-and-right direction or a different length in the front-and-rear direction.

[0213] The presser foot 81 not compatible with belt feed shown in FIG. 15D includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0214] The bottom plate 811 is composed only of the left-side portion of the stitch point portion 811a where stitch points are performed.

[0215] FIG. 15D is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81 that has a bottom plate 811 with a different width in the left-and-right direction or a different length in the front-and-rear direction.

[0216] The presser foot 81 not compatible with belt feed shown in FIG. 16A includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0217] The bottom plate 811 has a smaller left-and-right width on either the left-side portion or the right-side portion, compared to the bottom plate 811 of FIG. 11, with a stitch point portion 811a, which is formed as a cutout where stitch points are performed, serving as the boundary.

[0218] FIG. 16A is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81, such as a presser foot 81 that has a bottom plate 811 with a different width in the left-and-right direction or a different length in the front-and-rear direction, a presser foot 81 in which only one of the left and right sides of the stitch point portion 811a is narrower, a presser foot 81 with a different ratio between the left and right sides, or a presser foot 81 in which both sides are narrower.

[0219] The presser foot 81 not compatible with belt feed shown in FIG. 16B includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0220] The bottom plate 811 has a structure suitable for so-called concealed stitching.

[0221] In concealed stitching, sewing is performed in which a long sheet piece having fastener teeth (elements) arranged side by side along an end edge portion is stitched to a workpiece.

[0222] The bottom plate 811 has a structure 811b that, during stitching, lifts each fastener tooth to retract it from the stitch point position.

[0223] FIG. 16B is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81 for concealed stitching that has a bottom plate 811 with a different width in the left-and-right direction, a different length in the front-and-rear direction, or a different structure for lifting fastener teeth.

[0224] The presser foot 81 not compatible with belt feed shown in FIG. 16C includes a connecting portion 812 having a recessed groove 812a and a cutout 812b, and a bottom plate 811.

[0225] The bottom plate 811 has a structure suitable for so-called three-fold hem stitching.

[0226] In three-fold hem stitching, sewing is performed by forming a three-fold hem at a side end portion of a workpiece while stitching the three-fold hemmed portion along the side end portion.

[0227] The bottom plate 811 has a structure 811c suitable for feeding the three-fold hemmed portion, in which a raised portion at a rear end portion is raised higher on the right side of the stitch point position.

[0228] FIG. 16C is an example of the presser foot 81. Without being limited to this example, the sewing machine 100 can use any presser foot 81 for three-fold hemming, such as a presser foot 81 that has a bottom plate 811 with a width in the left-and-right direction, a length in the front-and-rear direction, and a raised portion on the left side, or a presser foot 81 having a different degree of raising.

[0229] The examples of presser feet not compatible with belt feed shown in FIGS. 15A to 16C are merely a few examples, and any type of presser foot can be attached to and used with the sewing machine 100.

[0230] In addition, the structure for attaching the presser foot 81 to the presser bar 72 is not limited to the downward extension 821 and the recessed groove 812a and cutout 812b, and any connecting structure that allows the presser foot to be detachably attached can be used.[Others]

[0231] 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.

[0232] For example, the lower feed mechanism 20 need not be a belt feed mechanism. For example, the characteristic configuration of the present disclosure (cloth presser mechanism 70, attachment structure 80, 80A, and the like) can also be applied to a sewing machine having a lower feed mechanism that feeds a workpiece on the throat plate 101 by feed dots.

[0233] The present application is based on Japanese Patent Application No. 2023-057249 filed on March 31, 2023, the contents of which are incorporated herein by reference.

Claims

1. A sewing machine comprising: an upper feed mechanism configured to feed a workpiece from above a throat plate by a conveyor belt; and a presser mechanism comprising a presser foot provided with a feed roller for the conveyor belt and a presser bar supporting the presser foot at a lower end portion, wherein the presser foot is detachable from the presser bar, and the sewing machine comprises an attachment structure configured to allow a presser foot, which is not provided with the feed roller for the conveyor belt and is not compatible with belt feed, to be attached to a lower portion of the presser bar.

2. The sewing machine according to claim 1, wherein the attachment structure comprises: a mounting base to which the presser foot provided with the feed roller for the conveyor belt is abutted and fixed, and a joint member interposed between the mounting base and the presser foot not compatible with belt feed.

3. The sewing machine according to claim 1 or 2, wherein the attachment structure comprises a downward extension configured to be fittable to an upper end portion of the presser foot not compatible with belt feed, and a connecting portion configured to connect the downward extension to the presser foot not compatible with belt feed.

4. The sewing machine according to claim 2, wherein the joint member comprises a downward extension configured to be fittable to an upper end portion of the presser foot not compatible with belt feed.

5. The sewing machine according to claim 1, wherein in the attachment structure, a height from a bottom of the presser foot to a lower end portion of the presser bar when the presser foot provided with the feed roller for the conveyor belt is attached matches a height from the bottom of the presser foot not compatible with belt feed to the lower end portion of the presser bar when the presser foot not compatible with belt feed is attached.

6. The sewing machine according to claim 1, wherein the presser foot provided with the feed roller for the conveyor belt comprises a belt guide supported by a support shaft, and a spring that applies a contact-press force toward a workpiece on the throat plate 101 to the conveyor belt conveyed by the belt guide.

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