Sewing – Elements – Shuttles
Reexamination Certificate
2003-12-19
2004-10-05
Izaguirre, Ismael (Department: 3765)
Sewing
Elements
Shuttles
C112S228000
Reexamination Certificate
active
06799527
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sewing machine shuttle that works together with a needle and take-up lever to form stitches on fabric.
2. Description of Related Art
Japanese laid-open patent publication number Hei 6-327873 (“JP '873”) describes a sewing machine shuttle as shown in
FIGS. 10A-10C
. This sewing machine shuttle
50
is equipped with an outer shuttle
52
rotated by a shuttle drive shaft
51
and an inner shuttle
53
housed inside the outer shuttle
52
so that rotation relative to the outer shuttle
52
is possible. A needle guide hole
54
is formed on the upper surface of the inner shuttle
53
and a rotation stopping recess portion
55
is formed on the front surface of the inner shuttle
53
in phase alignment with the hole
54
. A rotation stopping projection
57
of a shuttle stopping member
56
is loosely fitted in the rotation stopping recess portion
55
. The rotation stopping projection
57
stops the rotation of the inner shuttle
53
. An upper thread grasping section
58
and a guide plate
59
(referred to as a “spring”) are disposed on the outer perimeter of the outer shuttle
52
. On the rear side, in terms of the rotation direction of the outer shuttle, is formed an upper thread advancing projection
61
for feeding the upper thread forward. The projection
61
projects forward to the front edge of the guide plate
59
.
When a needle
62
rises slightly from the bottom dead center, the upper thread grasping section
58
grasps an upper thread Ta behind the needle
62
. As the outer shuttle
52
rotates, an upper thread loop is formed around the inner shuttle
53
. As
FIG. 10A
shows, as the upper thread loop expands, the upper thread advancing projection
61
pushes the upper thread Ta forward above the inner shuttle
53
so that the upper thread loop is pushed out from the outer perimeter surface of the inner shuttle
53
toward the front. As
FIG. 10B
shows, when the upper thread grasping section
58
reaches the lowermost section of the inner shuttle
53
, the upper thread Ta enters a gap between the rotation stopping recess portion
55
and the rotation stopping projection
57
. As
FIG. 10C
shows, the upper thread loop slides through the inner shuttle
53
. When the upper thread grasping section
58
is oriented upward, a take-up lever (not shown in the figure) pulls up the upper thread Ta. This upward pulling force from the take-up lever causes the upper thread Ta to slip through the abutment of the rotation stopping recess portion
55
and the rotation stopping projection
57
toward the rear, in terms of the rotation direction of the outer shuttle, and the upper thread Ta disengages from the inner shuttle
53
. Then, the upper thread Ta engages with a lower thread Tb, forming a stitch in the fabric W.
Japanese laid-open patent publication number Hei 11-244566 (“JP '566”) describes a sewing machine shuttle shown in
FIGS. 11A and 11B
. This sewing machine shuttle
70
is equipped with an abutment section
74
disposed on the outer perimeter of an inner shuttle
71
. On a shuttle-stopping member
75
, there is disposed a rotation stopping projection
76
loosely fitted in a rotation stopping recess portion
72
and a stopper
77
engaging with an abutment section
74
. When an outer shuttle
73
rotates, the abutment section
74
comes in contact with the stopper
77
. The shuttle-stopping member
75
is attached to a shuttle support body (not shown in the figure) in a manner that allows its position to be adjusted. By adjusting, ahead of time, the abutment position of the abutment section
74
and the stopper
77
, the gap between the rotation stopping recess portion
72
and the rotation stopping projection
76
can be made uniform both forward and back (in the direction of the rotation of the outer shuttle). Then, as shown in
FIG. 11B
, when the take-up lever pulls up the upper thread Ta, the upper thread Ta passes from front to back (relative to the rotation of the outer shuttle) through the gap between the rotation stopping recess portion
72
and the rotation stopping projection
76
, passing out of the inner shuttle
71
. With the sewing machine shuttle
50
of JP '873, however, an upward pulling force from the take-up lever is used on the upper thread Ta to disengage the upper thread Ta from the inner shuttle
53
by pulling it out from the abutment between the rotation stopping recess portion
55
and the rotation stopping projection
57
. As a result, the upper thread Ta receives a large resistance, leading to uneven tightness in the thread or, at times, breakage due to excessive tension. With the sewing machine shuttle
70
of JP '566, a gap that is uniform both forward and back is maintained for the rotation stopping projection
76
, thus allowing resistance acting on the upper thread Ta to be kept low. However, since this gap changes according to the position of the shuttle-stopping member
75
, it is necessary to make tedious fine adjustments to positioning each time the shuttle-stopping member
75
is disassembled for replacement and cleaning.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome the problems described above and to provide a sewing machine shuttle that allows, prior to the application of an upward-pulling force from a take-up lever and without the use of this upward-pulling force, an upper thread to be pulled from an internal shuttle while sliding through the abutment between a rotation stopping recess portion and a rotation stopping projection; prevents thread breakage and inconsistency in thread tension by avoiding resistance from the upper thread when the upward-pulling force of the take-up lever is applied; and stabilizes the action of the upper thread after it has been pulled from the inner shuttle.
In order to achieve the object described above, the sewing machine shuttle according to the present invention includes an outer shuttle rotated by a shuttle driving shaft, an inner shuttle housed in the outer shuttle rotatably relative to the outer shuttle, an upper thread grasping section disposed on the outer shuttle, a rotation stopping recess portion formed on the front side of the inner shuttle, a shuttle stopping member having a rotation stopping projection, said a rotation stopping projection being fitted loosely into the rotation stopping recess portion to allow the rotation of the inner shuttle to be stopped, and a projecting-forward upper thread release projection disposed on the front surface of the outer shuttle. While the upper thread grasping section is grasping and pulling the upper thread, the upper thread release projection pushes forward the upper thread which is droppped into the rotation stopping recess portion. This allows the upper thread to be slide out from the inner shuttle by being slid through the abutment between the rear side, in terms of the rotation of the outer shuttle, of the rotation stopping recess portion and rotation stopping projection.
In the sewing machine shuttle of the present invention, when the outer shuttle is rotated, the upper thread grasping section grasps the upper thread and an upper thread loop is formed around the inner shuttle. As the upper-thread loop is expanding, it drops into the rotation stopping recess portion of the front surface of the inner shuttle. Then, when the upper thread release projection reaches substantially same phase as the rotation stopping recess portion, the upper thread release projection pushes the upper thread forward as described above so that the upper thread slides through the abutment between the rear side, in terms of the rotation of the outer shuttle, of the rotation stopping recess portion and rotation stopping projection. In order to have the upper thread slide through the abutment with no misalignment, it would be preferable for the upper thread to be positioned near the abutment, i.e., at the rear side, in terms of the rotation of the outer shuttle of the rotation stopping recess portion.
In order to have the upper thr
Darby & Darby
Izaguirre Ismael
Kabushikikaisha Barudan
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