VERTICAL FULL-ROTATION SHUTTLE

Abstract

 In order to prevent occurrence of thread breakage and incidental looping, a thread escape recess (18) recessed radially outward relative to an imaginary cylindrical surface inscribed in an inner peripheral portion (17) of an inner shuttle (3) is provided adjacent to a downstream side in a direction of rotation (A) of a needle location hole (11).

Description

Technical Field

[0001] The present invention relates to a vertical full rotation shuttle provided on a sewing machine.

Background Art

[0002] A vertical full rotation shuttle of the related art is described in, for example, Patent Literature 1. The vertical full rotation shuttle of the related art includes an outer shuttle fixed to a lower shaft of the sewing machine and having a hook portion, an inner shuttle retained in a state of being accommodated in the outer shuttle, a bobbin case removably mounted in the inner shuttle, and a bobbin around which a lower thread is to be wound and configured to be accommodated in the bobbin case.

[0003] When a sewing action of the sewing machine is started, the lower shaft is driven to rotate in a predetermined direction of rotation about a horizontal axis of rotation, and a sewing needle repeats an action of moving toward and away from the axis of rotation along an axial line perpendicular to the axis of rotation of the lower shaft. A needle thread inserted through the sewing needle is caught by a hook portion and forms a needle thread loop. The needle thread loop moves along a surface of the inner shuttle and passes over the lower thread, which causes the needle thread to engage with the lower thread drawn out from the inner shuttle through a needle hole in a needle plate over a sewing machine head, and stitches are formed on an object to be sewed.

[0004] The inner shuttle includes a substantially cylindrical peripheral wall part, a bridge part that extends in one diameter direction so as to be connected to one end of the peripheral wall part in an axial direction thereof to form a bottom portion, a stud provided on the bridge part so as to extend upright toward the other end of the peripheral wall part in the axial direction, an outwardly extending flange that extends radially outward so as to be connected to the other end of the peripheral wall part in the axial direction, and a substantially C-shaped track projection that projects from an outer peripheral surface of the peripheral wall part and extends in a circumferential direction.

[0005] The peripheral wall part is provided with a needle location hole in which the sewing needle is inserted, and the inner shuttle is restricted from rotating by a retaining member which is connected to a proximal end thereof to a body of a sewing machine so that the needle location hole is always aligned with an axial line of the sewing needle and is prevented from rotating following the outer shuttle.

[0006] The peripheral wall part includes a thinned portion having a reduced thickness over a range of approximately 90° from the needle location hole to a downstream side in the direction of rotation of the outer shuttle in order to allow passage of the lower thread drawn out from the bobbin case. With the provision of the thinned portion as described above on the peripheral wall part thereof, a clearance which allows smooth passage of the lower thread is secured between an outer peripheral portion of the bobbin case and an inner peripheral portion of the inner shuttle, so that an unintended change in tension of the lower thread is prevented.

Citation List

Patent Literature

[0007] Patent Literature 1: JP-Y2 S61-14375 (1986)

Summary of Invention

Technical Problem

[0008] In the related art described above, when the sewing action of the sewing machine is stopped, a reciprocal displacement action of the sewing needle and a rotational action of the outer shuttle are stopped. However, the lower thread is drawn out from the bobbin case in association with advance of the stitches during a sewing operation. Therefore, the bobbin is rotated in the bobbin case by a tension applied by feeding of the lower thread. Even when the sewing action is stopped and the reciprocal displacement action of the sewing needle and the rotational action of the outer shuttle are stopped, the bobbin rotates due to inertia and the lower thread is discharged from the bobbin case. The lower thread discharged from the bobbin case stays in the above described narrow clearance between the inner peripheral portion of the inner shuttle and the outer peripheral portion of the bobbin case in a loosened state. Therefore, when the next sewing action starts, the lower thread in the clearance cannot be drawn out smoothly and thus may be tangled, so that yarn breakage and incidental looping may disadvantageously result.

[0009] An object of the invention is to provide a vertical full rotation shuttle that is capable of preventing occurrence of thread breakage and incidental looping.

Solution to Problem

[0010] The invention provides a vertical full rotation shuttle including:

an outer shuttle fixed to a lower shaft which is driven to rotate about an axis of rotation perpendicular to an axial line of a needle bar to which a sewing needle is attached and includes a hook portion with a distal end thereof tapered to a downstream side in a direction of rotation of the lower shaft;

an inner shuttle retained by the outer shuttle so as to rotate about the axis of rotation,

the inner shuttle including a peripheral wall part having a needle location hole in which the sewing needle is inserted, a thread escape recess being provided on an inner peripheral surface of the peripheral wall part on the downstream side in the direction of rotation of the needle location hole;

a bobbin case removably mounted in the inner shuttle; and

a bobbin accommodated in the bobbin case, a lower thread being to be wound around the bobbin.

[0011] In the invention, it is preferable that the thread escape recess decreases in depth from the needle location hole toward the downstream side in the direction of rotation.

[0012] In the invention, it is preferable that the thread escape recess increases in depth from the needle location hole toward the downstream side in the direction of rotation.

[0013] In the invention, it is preferable that the bobbin case includes an outwardly directed wall portion that extends downstream in the direction of rotation from the thread escape recess and extends from the bobbin case to an opening end of the inner shuttle so as to cover a gap between the bobbin case and the inner shuttle in a state in which the bobbin case is mounted in the inner shuttle.

[0014] In the invention, it is preferable that the inner shuttle includes an inwardly directed wall portion that extends downstream in the direction of rotation from the thread escape recess and extends from an opening end of the inner shuttle to the bobbin case so as to cover a gap between the bobbin case and the inner shuttle in a state in which the bobbin case is mounted in the inner shuttle.

Advantageous Effects of Invention

[0015] According to the invention, since the thread escape recess is provided in the inner shuttle, a clearance larger than a area where no thread escape recess is provided may be formed between an inner peripheral portion of the inner shuttle and an outer peripheral portion of the bobbin case. Therefore, when the sewing action is stopped, the lower thread drawn out from between the inner peripheral portion of the inner shuttle and the outer peripheral portion of the bobbin case by the rotation of the bobbin due to inertia may accumulate in a large clearance between the thread escape recess and the outer peripheral portion of the bobbin case in a loosened state. Accordingly, when the sewing action is started again, the lower thread accumulating in the clearance is drawn out smoothly without being tangled and occurrence of thread breakage and incidental looping may be prevented.

[0016] According to the invention, since the thread escape recess decreases in depth toward the downstream side in the direction of rotation, the lower thread that enters the clearance between the thread escape recess and the outer peripheral portion of the bobbin case is guided toward the needle location hole by the downstream-side bottom surface part, so that dense accumulation of the lower thread in the clearance is prevented, and the lower thread can be discharged from the clearance more smoothly.

[0017] According to the invention, since the thread escape recess increases in depth toward the downstream side in the direction of rotation, the lower thread that enters the clearance between the thread escape recess and the outer peripheral portion of the bobbin case is guided to the downstream side in the direction of rotation by the upstream-side bottom surface part, which is away from the needle location hole, so that dense accumulation of the lower thread in the clearance is prevented, and the lower thread can be discharged from the clearance more smoothly.

[0018] According to the invention, since the outwardly directed wall portion is provided on the bobbin case, the lower thread is prevented from failing to be accommodated completely in the thread escape recess and protruding from between the inner shuttle and the bobbin case when the lower thread is loosened, and the lower thread may be prevented from interfering an upper thread that passes over the lower thread and causing a tensile force of the upper thread to unintentionally changed.

[0019] According to the invention, since the inwardly directed wall portion is provided on the inner shuttle, the lower thread is prevented from failing to be accommodated completely in the thread escape recess and protruding from between the inner shuttle and the bobbin case when the lower thread is loosened, and the lower thread is prevented from interfering the upper thread that passes over the lower thread and causing a tensile force of the upper thread to unintentionally changed.

Brief Description of Drawings

[0020] Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:

FIG. 1 is a cross-sectional view of an inner shuttle 3 provided in a vertical full rotation shuttle 1 according to one embodiment of the invention viewed from the front;

FIG. 2 is a front view of the vertical full rotation shuttle 1;

FIG. 3 is a cross-sectional view of the vertical full rotation shuttle 1 taken along the line II-II in FIG. 2;

FIG. 4 is a perspective view of the inner shuttle 3;

FIG. 5 is a left side view of the inner shuttle 3;

FIG. 6 is a front view of the inner shuttle 3;

FIG. 7 is a cross-sectional view of the inner shuttle 3 taken along the line VII-VII in FIG. 6;

FIG. 8 is an enlarged front view of a portion of the inner shuttle 3 near the thread escape recess 18;

FIG. 9 is an enlarged perspective view illustrating parts of an inner shuttle 3a, the bobbin 4, and the bobbin case 5 provided in a vertical full rotation shuttle 1a according to another embodiment of the invention;

FIG. 10 is a cross-sectional view of the inner shuttle 3a provided in the vertical full rotation shuttle 1a;

FIG. 11 is a cross-sectional view of the inner shuttle 3a taken along the line XI-XI in FIG. 10;

FIG. 12 is a perspective view of an inner shuttle 3b provided in a vertical full rotation shuttle 1b according to still another embodiment of the invention;

FIG. 13 is a cross-sectional view of the inner shuttle 3b;

FIG. 14 is a cross-sectional view of the inner shuttle 3b taken along the line XIV-XIV in FIG. 12;

FIG. 15 is a front view of a vertical full rotation shuttle 1c according to still another embodiment of the invention;

FIG. 16 is a cross-sectional view of an inner shuttle 3c provided on the vertical full rotation shuttle 1c;

FIG. 17 is a cross-sectional view of the inner shuttle 3c taken along the line XVII-XVII in FIG. 16;

FIG. 18 is a perspective view of a vertical full rotation shuttle 1d according to still another embodiment of the invention;

FIG. 19 is a cross-sectional view of an inner shuttle 3d provided on the vertical full rotation shuttle 1d; and

FIG. 20 is a cross-sectional view of the inner shuttle 3d taken along the line XX-XX in FIG. 19.

Description of Embodiments

[0021] Referring now to the drawings, preferred embodiments of the invention will be described in detail.

[0022] FIG. 1 is a cross-sectional view of an inner shuttle 3 provided in a vertical full rotation shuttle 1 according to one embodiment of the invention viewed from the front, FIG. 2 is a front view of the vertical full rotation shuttle 1, and FIG. 3 is a cross-sectional view of the vertical full rotation shuttle 1 taken along the line II-II in FIG. 2. FIG. 4 is a perspective view of the inner shuttle 3, and FIG. 5 is a left side view of the inner shuttle 3. FIG. 1 is a cross-sectional view of the inner shuttle 3 taken along the line I-I in FIG. 5.

[0023] The vertical full rotation shuttle 1 of the invention includes an outer shuttle 2, the inner shuttle 3, a bobbin 4, and a bobbin case 5. The outer shuttle 2 is fixed to a lower shaft 8 that is driven to rotate in a direction indicated by an arrow A about an axis of rotation L2, which is perpendicular to an axial line L1 of a needle bar 7 on which a sewing needle 6 is detachably coaxially mounted. The outer shuttle 2 includes a tapered hook portion 9 having a distal end facing the downstream side in the direction of rotation A of the lower shaft 8.

[0024] The inner shuttle 3 is put into the outer shuttle 2, and a projection of a retaining member, which is not illustrated, is fitted into a recess 10 to restrict the inner shuttle 3 from rotating. The inner shuttle 3 includes: a peripheral wall part 12 provided with a needle location hole 11 through which the sewing needle 6 is inserted; a bottom portion 13, also referred to as a bridge, which is connected to one end of the peripheral wall part 12 in an axial direction thereof and extends in one diameter direction and; a stud 14 provided perpendicularly upright from a center of the bottom portion 13 toward the other end of the peripheral wall part 12 in the axial direction thereof; a flange part 15 which is connected to the other end of the peripheral wall part 12 in the axial direction thereof and is formed so as to extend radially outward; and a track projection 16 formed on the peripheral wall part 12 so as to project from an outer peripheral surface thereof.

[0025] The outer shuttle 2 and the inner shuttle 3 are formed, for example, of carburized carbon steel, and are provided with a hardness of 650 HV or more by thermal treatment. The bobbin 4 and the bobbin case 5 are formed of iron steel or stainless steel.
the recess 10 described above is formed in the flange part 15, the needle location hole 11 described above is formed behind the recess 10, that is, on one end side of the peripheral wall part 12 in the axial direction thereof, and a lower thread guiding groove 35 which opens toward a fitting space which is defined by the recess 10 and to which the projection of the retaining member described above and not illustrated fits, from the downstream side in the direction of rotation A, is formed. The lower thread guiding groove 35 allows insertion of a lower thread 21 drawn out from between a peripheral wall part of the bobbin case 5 and a thread tensioning spring 33 provided on the peripheral wall part, so that the lower thread 21 passing through a needle hole 36 of a needle plate provided on a sewing machine head in a tensed manner is maintained in a state of being fitted in the lower thread guiding groove 35 and prevented from being protruded outside the recess 10 even though the lower thread 21 is loosened by a thread cutting action of a thread cutter, not illustrated, while leaving the recess 10 and coming apart completely at the time of passing over.

[0026] In the inner shuttle 3 configured in this manner, a thread escape recess 18 is provided on an inner peripheral portion 17 at a position on the downstream side in the direction of rotation A of the needle drop hole 11, the thread escape recess 18 being depressed radially outward, i.e., toward the outer periphery, with respect to an imaginary cylindrical surface which inscribes the inner peripheral portion 17. Detailed description of the thread escape recess 18 will be given later.

[0027] The bobbin case 5 is removably mounted in the inner shuttle 3, and the bobbin 4 having the lower thread 21, which is referred to as a bobbin thread, wound therearound is accommodated in the bobbin case 5. The bobbin case 5 is provided with a first notch 22 that allows downward movement of the sewing needle 6. The notch 22 is formed in the peripheral wall part of the bobbin case 5 so as to extend in the axial direction. The notch 22 continues to a second notch 23.

[0028] The inner peripheral portion 17 of the inner shuttle 3 is provided with a pair of projections 24. The projections 24 come into contact with an inner surface of the peripheral wall part of the bobbin case 5 that opposes via the notch 23. In this configuration, when mounting the bobbin case 5 in the inner shuttle 3, insertion of the bobbin case 5 into the inner shuttle 3 is guided, and relative angular displacement between the bobbin case 5 and the inner shuttle 3 is restricted in cooperation with a latch mechanism 25.

[0029] The latch mechanism 25 includes an operating lever 26 and an engaging strip 27, restricts the angular displacement between the inner shuttle 3 and the bobbin case 5 by the engaging strip 27 engaging with an engaging recess 28 formed on the inner shuttle 3, and locks the bobbin case 5 with respect to the inner shuttle 3 and prevents the same from coming out therefrom. When replacing the bobbin 4, by releasing the locked state of the bobbin case 5 with respect to the inner shuttle 3, the latch mechanism 25 can release the bobbin case 5 from the inner shuttle 3.

[0030] FIG. 6 is a front view of the inner shuttle 3; FIG. 7 is a cross-sectional view of the inner shuttle 3 taken along the line VII-VII in FIG. 6; and FIG. 8 is an enlarged front view of a portion of the inner shuttle 3 near the thread escape recess 18. The thread escape recess 18 includes an upstream-side bottom surface part 31 extending away from an imaginary cylindrical surface and being curved to protrude radially outward to increase in depth toward a downstream side in the direction of rotation A of the needle location hole 11, and a downstream-side bottom surface part 32 continuing to an end of the upstream-side bottom surface part 31 on the downstream in the direction of rotation A, extending toward the imaginary cylindrical surface, and being curved to protrude radially outward to decrease in depth toward a downstream side in the direction of rotation A of the needle location hole 11.

[0031] The upstream-side bottom surface part 31 and the downstream-side bottom surface part 32 are included to constitute a bottom surface part 30 that is formed of part of a vertical cylindrical surface having a radius R1. If an inner diameter D1 of the imaginary cylindrical surface falls in a range of 22. 8 mm or more and 27.6 mm or less, the radius R1 is selected from a range of 2 mm or more and 8 mm or less. In this case, a starting point P1 is set to a position at an angle θ1 on the downstream side in the direction of rotation A of an imaginary plane including the axial line L1 of the needle bar 7 and the axis of rotation L2 of the lower shaft 8. An intermediate point P2, which is a flexion point between the upstream-side bottom surface part 31 and the downstream-side bottom surface part 32 is set to a position at an angle θ2 on the downstream side in the direction of rotation A of the imaginary plane. Furthermore, an end point P3 is set to a position at an angle θ3 on the downstream side in the direction of rotation A of the imaginary plane. The angle θ1 falls in a range of 20° or more and 40° or less, the angle θ2 falls in a range of 30° or more and 60° or less, and the angle θ3 falls in a range of 40° or more and 70° or less.

[0032] With the provision of the thread escape recess 18 as described above on the inner peripheral portion 17 of the inner shuttle 3, a larger clearance may be secured compared with an area between the inner peripheral portion 17 of the inner shuttle 3 and the outer peripheral portion of the bobbin case 5 where the above-described thread escape recess 18 is not provided, that is, the area downstream of the angle θ3 in the direction of rotation A. Therefore, when the sewing action is stopped and the upward and downward movement of the needle bar 7 and the rotation of the lower shaft 8 are stopped, the lower thread 21 drawn out from between the thread tensioning spring 33 and the outer peripheral portion of the bobbin case 5 into a space between the inner peripheral portion 17 of the inner shuttle 3 and the outer peripheral portion of the bobbin case 5 by the rotation of the bobbin 4 due to inertia is allowed to enter a large clearance between the thread escape recess 18 and the outer peripheral portion of the bobbin case 5 in a loose state and accumulate therein.

[0033] Accordingly, when the sewing action is started again, the lower thread 21 that is accumulated in the large clearance can be drawn out smoothly without being tangled, and occurrence of thread breakage or incidental looping may be prevented.

[0034] In addition, the thread escape recess 18 is provided with the downstream-side bottom surface part 32, and thus the lower thread 21 that enters the large clearance between the thread escape recess 18 and the outer peripheral portion of the bobbin case 5 is guided toward the needle location hole 11, that is, to the upstream side in the direction of rotation A by the downstream-side bottom surface part 32, so that dense accumulation of the lower thread 21 in the large clearance may be prevented. Accordingly, the lower thread 21 may be discharged further smoothly from the large clearance.

[0035] FIG. 9 is an enlarged perspective view illustrating parts of an inner shuttle 3a, the bobbin 4, and the bobbin case 5 provided in a vertical full rotation shuttle 1a according to another embodiment of the invention; FIG. 10 is a cross-sectional view of the inner shuttle 3a provided in the vertical full rotation shuttle 1a; and FIG. 11 is a cross-sectional view of the inner shuttle 3a taken along the line XI-XI in FIG. 10. FIG. 10 is a cross-sectional view of the inner shuttle 3a taken along the line X-X in FIG. 11. Portions corresponding to the above-described embodiment are denoted by the same reference numerals and overlapped description will be omitted.

[0036] The vertical full rotation shuttle 1a of this embodiment includes the outer shuttle 2, the inner shuttle 3a, the bobbin 4, and the bobbin case 5. In the flange part 15 of the inner shuttle 3a are formed the lower thread guiding groove 35 that opens toward a fitting space defined by the recess 10 from the downstream side in the direction of rotation A, and a thread escape recess 18a that opens toward the lower thread guiding groove 35 from the downstream side in the direction of rotation A.

[0037] The thread escape recess 18a continues to the lower thread guiding groove 35 on the downstream side in the direction of rotation A, and is formed on the downstream side in the direction of rotation A of the needle location hole 11 when viewed from the front. Since such a thread escape recess 18a is formed in the inner shuttle 3a, in the same manner as the embodiment described above, the lower thread 21 can be retracted from the lower thread guiding groove 35 to a space in the interior of the thread escape recess 18a even though the lower thread is loosened due to the cutting operation of a thread cutter while leaving the recess 10 and coming apart completely at the time of passing over, so that it is possible to suppress protrusion of the lower thread 21 from the recess 10.

[0038] FIG. 12 is a perspective view of an inner shuttle 3b provided in a vertical full rotation shuttle 1b according to still another embodiment of the invention; FIG. 13 is a cross-sectional view of the inner shuttle 3b; and FIG. 14 is a cross-sectional view of the inner shuttle 3b taken along the line XIV-XIV in FIG. 12. FIG. 13 illustrates a cross section of the inner shuttle 3b taken along the line XIII-XIII in FIG. 14. Portions corresponding to the above-described embodiments are denoted by the same reference numerals and overlapped description will be omitted.

[0039] The vertical full rotation shuttle 1b of this embodiment includes the outer shuttle 2, the inner shuttle 3b, the bobbin 4, and the bobbin case 5. The flange part 15 of the inner shuttle 3b includes the lower thread guiding groove 35 opening toward a fitting space defined by the recess 10 from the downstream side in the direction of rotation A, a first thread escape recess 18b1 opening toward the lower thread guiding groove 35 from the downstream side in the direction of rotation A, and a second thread escape recess 18b2 depressed radially outward with respect to an imaginary cylindrical surface which inscribes on the inner peripheral portion, the second thread escape recess 18b2 being formed on the inner peripheral portion 17 of the peripheral wall part 12 at a position on the downstream side of the needle location hole 11 in the direction of rotation A. In this embodiment, the first thread escape recess 18b1 and the second thread escape recess 18b2 are included to constitute the thread escape recess.

[0040] An end of the first thread escape recess 18b1 on the downstream side in the direction of rotation A communicates with the second thread escape recess 18b2 at the bottom portion 13 in the direction of the axis of rotation L2. When the lower thread 21 is loosened as described above, the lower thread 21 in the lower thread guiding groove 35 enters the first thread escape recess 18b1, and when the lower thread 21 is further loosened, the lower thread 21 enters the second thread escape recess 18b2 and is retracted, so that the lower thread 21 may be prevented from protruding from the recess 10.

[0041] FIG. 15 is a front view of a vertical full rotation shuttle 1c according to still another embodiment of the invention; FIG. 16 is a cross-sectional view of an inner shuttle 3c provided on the vertical full rotation shuttle 1c; and FIG. 17 is a cross-sectional view of the inner shuttle 3c taken along the line XVII-XVII in FIG. 16. FIG. 16 illustrates a cross section of the inner shuttle 3c taken along the line XVI-XVI in FIG. 17. Portions corresponding to the above-described embodiments are denoted by the same reference numerals and overlapped description will be omitted.

[0042] The vertical full rotation shuttle 1c of this embodiment includes the outer shuttle 2, the inner shuttle 3c, the bobbin 4, and a bobbin case 5c. In the inner shuttle 3c is formed a thread escape recess 18c similar to the thread escape recess 18 formed on the inner shuttle 3 of the embodiments illustrated in FIG. 1 to FIG. 8 described above. In a peripheral wall part of the bobbin case 5c is formed an outwardly directed wall portion 37 which extends downstream in the direction of rotation A from a portion near an end of the thread escape recess 18c on the downstream side in the direction of rotation A by a predetermined angle θ11 and protruding radially outward of the bobbin case 5c so as to cover partly a peripheral edge portion of an opening end of the inner shuttle 3c in a state in which the bobbin case 5c is mounted in the inner shuttle 3c. In FIG. 15, the outwardly directed wall portion 37 is illustrated by hatching for easy understanding of the drawing.

[0043] The outwardly directed wall portion 37 has a thickness T1 of approximately 1 mm, and an angle θ11 selected from a range of 15° or more and 35° or less in a direction parallel to the axis of rotation L2. A projecting height H1 of the outwardly directed wall portion 37 from an outer periphery of the peripheral wall part of the bobbin case 5c on one radial line is selected from a range of 1 mm or more and 1.5 mm or less, and is set so as not to interfere with the inner shuttle 3c by coming into contact therewith.

[0044] By using the bobbin case 5c having the outwardly directed wall portion 37 as described thus far, the lower thread 21 is prevented from failing to be accommodated completely in the recess defined by the thread escape recess 18 and protruding toward the opening end (vertically near side in the paper of FIG. 15) of the inner shuttle from between the inner shuttle 3c and the bobbin case 5c when the lower thread 21 is loosened as described above, and interference of the lower thread 21 with respect to the upper thread (upper thread loop) that passes over the lower thread 21 is prevented, so that an unintended change in tension of the lower thread 21 and the upper thread may be prevented.

[0045] FIG. 18 is a perspective view of a vertical full rotation shuttle 1d according to still another embodiment of the invention; FIG. 19 is a cross-sectional view of an inner shuttle 3d provided on the vertical full rotation shuttle 1d; and FIG. 20 is a cross-sectional view of the inner shuttle 3d taken along the line XX-XX in FIG. 19. In FIG. 18, the outer shuttle 2 is omitted for easy understanding of the drawing, and FIG. 19 illustrates a cross section of the inner shuttle 3d taken along the line XIX-XIX in FIG. 20. Portions corresponding to the above-described embodiments are denoted by the same reference numerals and overlapped description will be omitted.

[0046] The vertical full rotation shuttle 1d of this embodiment includes the outer shuttle 2, the inner shuttle 3d, the bobbin 4, and the bobbin case 5c. The inner shuttle 3d includes a thread escape recess 18d, which is similar to the thread escape recess 18 described above, and an inwardly directed wall portion 38 extending downstream in the direction of rotation A by a predetermined angle θ12 from a portion near the end on the downstream side in the direction of rotation A of the thread escape recess 18d and formed on an inner periphery of a peripheral edge portion of an opening end of the inner shuttle 3d so as to close a gap from the inner periphery of the peripheral edge portion of the opening end of the inner shuttle 3d to a portion near an outer peripheral surface of the peripheral wall part of the mounted bobbin case 5. In FIG. 18, the inwardly directed wall portion 38 is illustrated by hatching for easy understanding of the drawing.

[0047] The inwardly directed wall portion 38 has a thickness T2 of approximately 1 mm, and an angle θ12 selected from a range of 10° or more and 30° or less in the direction parallel to the axis of rotation L2. A projecting height H2 of the inwardly directed wall portion 38 from the inner peripheral surface of the peripheral edge portion of the opening end of the inner shuttle 3d on one radial line thereof is selected from a range of 1 mm or more and 1.5 mm or less, and is set so as not to interfere with the bobbin case 5 by coming into contact therewith.

[0048] By using the inner shuttle 3d having the inwardly directed wall portion 38 as described thus far, the lower thread 21 is prevented from failing to be accommodated completely in the recess formed by the thread escape recess 18d and protruding toward the opening end (left side in FIG. 19) of the inner shuttle from between the inner shuttle 3d and the bobbin case 5 when the lower thread 21 is loosened as described above, and interference of the lower thread 21 with respect to the upper thread (upper thread loop) that passes over the lower thread 21 is prevented, so that an unintended change in tension of the lower thread 21 and the upper thread may be prevented.

[0049] In addition, the thread escape recess 18 is provided with the upstream-side bottom surface part 31, and thus the lower thread 21 that enters the large clearance between the thread escape recess 18 and the outer peripheral portion of the bobbin case 5 is guided in a direction away from the needle location hole 11, that is, to the downstream side in the direction of rotation A, by the upstream-side bottom surface part 31, so that dense accumulation of the lower thread 21 may be prevented in the large clearance. Accordingly, the lower thread 21 may be discharged further smoothly from the large clearance.

[0050] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.

Reference Signs List

[0051] 

1, 1a, 1b, 1c, 1d:

Vertical full rotation shuttle

2:

Outer shuttle

3, 3a, 3b, 3c, 3d:

Inner shuttle

4:

Bobbin

5, 5c:

Bobbin case

6:

Sewing needle

7:

Needle bar

8:

Lower shaft

9:

Hook portion

10:

Recess

11:

Needle location hole

12:

Peripheral wall part

13:

Bottom portion

14:

Stud

15:

Flange part

16:

Track projection

17:

Inner peripheral portion

18; 18a; 18b1; 18b2; 18c:

Thread escape recess

21:

Lower thread

22:

Notch

23:

Notch

24:

Projection

25:

Latch mechanism

26:

Operating lever

27:

Engaging strip

28:

Engaging recess

30:

Bottom surface part

31:

Upstream-side bottom surface part

32:

Downstream-side bottom surface part

33:

Thread tensioning spring

35:

Lower thread guiding groove

36:

Needle hole

37:

Outwardly directed wall portion

38:

Inwardly directed wall portion

Claims

1. A vertical full rotation shuttle, comprising:

an outer shuttle fixed to a lower shaft which is driven to rotate about an axis of rotation perpendicular to an axial line of a needle bar to which a sewing needle is attached and includes a hook portion with a distal end thereof tapered toward a downstream side in the direction of rotation of the lower shaft;

an inner shuttle retained by the outer shuttle so as to rotate about the axis of rotation,

the inner shuttle including a peripheral wall part having a needle location hole in which the sewing needle is inserted, a thread escape recess being provided on an inner peripheral surface of the peripheral wall part on the downstream side in the direction of rotation of the needle location hole;

a bobbin case removably mounted in the inner shuttle; and

a bobbin accommodated in the bobbin case, a lower thread being to be wound around the bobbin.

2. The vertical full rotation shuttle according to claim 1, wherein the thread escape recess decreases in depth from the needle location hole toward the downstream side in the direction of rotation.

3. The vertical full rotation shuttle according to claim 1, wherein the thread escape recess increases in depth from the needle location hole toward the downstream side in the direction of rotation.

4. The vertical full rotation shuttle according to any one of claims 1 to 3, wherein the bobbin case includes an outwardly directed wall portion that extends downstream in the direction of rotation from the thread escape recess and extends from the bobbin case to an opening end of the inner shuttle so as to close a gap between the bobbin case and the inner shuttle in a state in which the bobbin case is mounted in the inner shuttle.

5. The vertical full rotation shuttle according to any one of claims 1 to 3, wherein the inner shuttle includes an inwardly directed wall portion that extends downstream in the direction of rotation from the thread escape recess and extends from an opening end of the inner shuttle to the bobbin case so as to close a gap between the bobbin case and the inner shuttle in a state in which the bobbin case is mounted in the inner shuttle.

Drawing