U.S. patent application number 13/214768 was filed with the patent office on 2012-09-06 for bobbin case for a sewing machine.
Invention is credited to SHUI-CHUN TSENG.
Application Number | 20120222598 13/214768 |
Document ID | / |
Family ID | 46752485 |
Filed Date | 2012-09-06 |
United States Patent
Application |
20120222598 |
Kind Code |
A1 |
TSENG; SHUI-CHUN |
September 6, 2012 |
BOBBIN CASE FOR A SEWING MACHINE
Abstract
A bobbin case is used in a sewing machine for mounting a bobbin,
and includes a case body having a base wall, a case shaft extending
along a central line from the base wall for rotatably mounting the
bobbin, and a rim having entry and exit holes to define a
tensioning path therebetween, and a diverting concaivity configured
to divert a running route which is disposed downstream of the
tensioning path. A lead-out member is disposed downstream of the
running route. A leaf spring is positioned on the rim, and is
configured to guide an under thread of the bobbin to run along the
tensioning path with an urging force, and continued on running
along the running route to the lead-out member to be interlocked
with an upper thread for a sewing action.
Inventors: |
TSENG; SHUI-CHUN; (Taichung
City, TW) |
Family ID: |
46752485 |
Appl. No.: |
13/214768 |
Filed: |
August 22, 2011 |
Current U.S.
Class: |
112/231 |
Current CPC
Class: |
D05B 57/26 20130101 |
Class at
Publication: |
112/231 |
International
Class: |
D05B 57/26 20060101
D05B057/26 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 4, 2011 |
TW |
100107384 |
Claims
1. A bobbin case adapted to be used in a sewing machine for
mounting a bobbin which is disposed under a needle plate to supply
an under thread, the bobbin case comprising: a case body having a
base wall which defines an annular marginal region that surrounds a
central line, and which has a portion cut out so as to form an
offset surface that is offset from the central line, a case shaft
which extends from said base wall along the central line, and which
is configured to permit the bobbin to be rotatably sleeved thereon
so as to reel off the under thread to be led outwardly of said
annular marginal region, and front and rear rim segments which
extend from said annular marginal region in a direction of the
central line, and which are interconnected by said offset surface,
said front rim segment extending angularly to terminate at a
longitudinally extending edge, and having entry and exit holes
which are angularly displaced from each other to define a
tensioning path therebetween, and a diverting concavity which
extends from said longitudinally extending edge angularly and
toward said exit hole, and which is configured to divert a running
route which is disposed downstream of the tensioning path, inwardly
of said annular marginal region; a lead-out member disposed on said
offset surface and downstream of said diverting concavity for
further leading the under thread toward the needle plate; and a
leaf spring which has a positioned segment disposed to be fastened
to said front rim segment, and an urging segment which extends
lengthwise from said positioned segment to terminate at a guiding
end that is engaged in said exit hole, and that is configured to
guide the under thread to run along the running route to said
lead-out member through said diverting concavity, said urging
segment being provided with an urging force such that the under
thread led out of said entry hole to run along the tensioning path
is subject to the urging force so as to be placed in a tensed state
when the under thread exits said guiding end for continuing on
running along the running route.
2. The bobbin case according to claim 1, wherein said front rim
segment extends in the direction of the central line to terminate
at a circumferentially extending edge, and has outer and inner
surface regions radially opposite to each other, said outer surface
region having an inclined slit which extends through said inner
surface region and which communicates said circumferentially
extending edge with said entry hole so as to permit the under
thread to be guided through said inclined slit into said entry
hole.
3. The bobbin case according to claim 2, wherein said guiding end
is integrally formed with said urging segment and is bent to form a
bearing surface facing said circumferentially extending edge.
4. The bobbin case according to claim 3, wherein said diverting
concavity has a diverting surface which is disposed to face said
circumferentially extending edge and which is inclined gradually
from said outer surface region to said inner surface region.
5. The bobbin case according to claim 1, wherein said lead-out
member is in form of a coil which defines a through passage for
passage of the under thread.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a sewing machine, more
particularly to a bobbin case used in a sewing machine for mounting
a bobbin that supplies an under thread.
[0003] 2. Description of the Related Art
[0004] A sewing machine generally has a rotary shuttle device which
is disposed under a needle plate for supplying an under thread, and
which includes a hook driven to rotate about a horizontal axis, a
bobbin case holder housed in the hook, and a bobbin case detachably
attached to the bobbin case holder for receiving a bobbin on which
the under thread is wound. During a sewing operation, the hook is
rotated relative to the bobbin case holder, and the under thread is
pulled out and supplied through the bobbin case to a lower portion
of a piece of cloth to be sewn. The bobbin case is provided to
guide the under thread pulled out of the bobbin upward for
interlocking with an upper thread supplied from a needle above the
needle plate.
[0005] Referring to FIGS. 1 and 2, a conventional bobbin case is
shown to include a case body 1 and a leaf spring 2. The case body 1
has a base wall 101, a shaft 103 extending from the base wall 101
along a central line that is in line with a horizontal axis of a
hook of a rotary shuttle device when the bobbin case is received in
a bobbin case holder, and a peripheral wall 102 extending from an
annular marginal region of the base wall 101 in a direction of the
central line and configured to open at a top 106. The peripheral
wall 102 has an inclined slit 104 extending therethrough to permit
an under thread 301 of a bobbin 3 to be led out through the
peripheral wall 102. The under thread 301 is held between the leaf
spring 2 and the peripheral wall 102 in a tensed state, is guided
by a guiding end 201 of the leaf spring 2 that is engaged in an
exit hole 105 in the peripheral wall 102, and runs through a
lead-out member 107.
[0006] Referring to FIG. 3, during a sewing operation, the under
thread 301 is liable to slip off the guiding end 201 and toward the
base wall 101 so that the tension force applied to the under thread
301 is insufficient, thereby adversely affecting sewing
quality.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide a bobbin
case which can ensure that an under thread of a bobbin received
therein is held in a tensed state.
[0008] According to this invention, the bobbin case includes a case
body having a base wall which defines an annular marginal region
that surrounds a central line, and which has a portion cut out so
as to form an offset surface that is offset from the central line,
a case shaft which extends from the base wall along the central
line, and which is configured to permit a bobbin to be rotatably
sleeved thereon so as to reel off an under thread to be led
outwardly of the annular marginal region, and front and rear rim
segments which extend from the annular marginal region in a
direction of the central line, and which are interconnected by the
offset surface. The front rim segment extends angularly to
terminate at a longitudinally extending edge, and has entry and
exit holes which are angularly displaced from each other to define
a tensioning path therebetween, and a diverting concavity which
extends from the longitudinally extending edge angularly and toward
the exit hole, and which is configured to divert a running route
which is disposed downstream of the tensioning path, inwardly of
the annular marginal region. A lead-out member is disposed on the
offset surface and downstream of the diverting concavity for
further leading the under thread toward a needle plate. A leaf
spring has a positioned segment disposed to be fastened to the
front rim segment, and an urging segment which extends lengthwise
from the positioned segment to terminate at a guiding end that is
engaged in the exit hole, and that is configured to guide the under
thread to run along the running route to the lead-out member
through the diverting concavity. The urging segment is provided
with an urging force such that the under thread led out of the
entry hole to run along the tensioning path is subject to the
urging force so as to be placed in a tensed state when the under
thread exits the guiding end for continuing on running along the
running route.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other features and advantages of the present invention will
become apparent in the following detailed description of the
preferred embodiment of the invention, with reference to the
accompanying drawings, in which:
[0010] FIG. 1 is a perspective view of a conventional bobbin case
and a bobbin;
[0011] FIG. 2 is a perspective view of the conventional bobbin case
in which the bobbin is mounted;
[0012] FIG. 3 is a perspective view of the conventional bobbin case
when an under thread of the bobbin is slipped off;
[0013] FIG. 4 is a perspective view of the preferred embodiment of
a bobbin case according to this invention, and a bobbin;
[0014] FIG. 5 is a side view of the preferred embodiment; and
[0015] FIG. 6 is a perspective view of the preferred embodiment in
which the bobbin is mounted.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] Referring to FIGS. 4 to 6, the preferred embodiment of a
bobbin case according to the present invention is shown to comprise
a case body 10, a lead-out member 16, and a leaf spring 20.
[0017] The case body 10 has a base wall 11 which defines an annular
marginal region 111 that surrounds a central line (X) that is in
line with a horizontal axis of a hook (not shown) when received in
the hook, and which has a portion cut out so as to form an offset
surface 112 that is offset from the central line (X), a case shaft
14 which extends from the base wall 11 along the central line (X),
and which is configured to permit a bobbin 100 to be rotatably
sleeved thereon so as to reel off an under thread 110 to be led
outwardly of the annular marginal region 111, and a rim 12
extending from the annular marginal region 111 in a direction of
the central line (X) to terminate at a circumferentially extending
edge 121. The rim 12 includes front and rear rim segments (12a,
12b) which are interconnected by the offset surface 112. The front
rim segment (12a) extends angularly to terminate at a
longitudinally extending edge 15, and has outer and inner surface
regions 13, 18 radially opposite to each other. The outer surface
region 13 has an inclined slit 122 which extends through the inner
surface region 18 and which communicates the circumferentially
extending edge 121 with an entry hole 124 so as to permit the under
thread 110 to be guided through the inclined slit 122 into the
entry hole 124. An exit hole 123 is angularly displaced from the
entry hole 124 to define a tensioning path (P) therebetween. A
diverting concavity 17 extends from the longitudinally extending
edge 15 angularly and toward the exit hole 123, and has a diverting
surface 171 which is disposed to face the circumferentially
extending edge 121 and which is inclined gradually from the outer
surface region 13 to the inner surface region 18. Thus, the
diverting surface 171 can divert a running route (R) which is
disposed downstream of the tensioning path (P), inwardly of the
annular marginal region 111.
[0018] The lead-out member 16 is disposed on the offset surface 112
and downstream of the diverting concavity 17 for further leading
the under thread 110 toward a needle plate (not shown) of a sewing
machine. In this embodiment, the lead-out member 16 is in the form
of a coil which defines a through passage 161 for passage of the
under thread 110.
[0019] The leaf spring 20 has a positioned segment 22 disposed to
be fastened to the front rim segment (12a), and an urging segment
23 which extends lengthwise from the positioned segment 22 to
terminate at a guiding end 21 that is engaged in the exit hole 123,
and that is bent to forma bearing surface 211 facing the
circumferentially extending edge 121 so as to guide the under
thread 110 to run along the running route (R) to the lead-out
member 16 through the diverting concavity 17. The urging segment 23
is provided with an urging force such that the under thread 110 led
out of the entry hole 124 to run along the tensioning path (P) is
subject to the urging force so as to be placed in a tensed state
when the under thread 110 exits the guiding end 21 for continuing
on running along the running route (R).
[0020] As illustrated, with provision of the diverting concavity 17
that can divert the running route (R) downstream of the tensioning
path (P) and inwardly of the annular marginal region 111, when
performing a sewing operation, the under thread 110 can run along
the running route (R) while being subject to the urging force to be
placed in the tensed state. Slippage of the under thread 110 off
the guiding end 21 can be avoided, thereby ensuring the under
thread 110 to be in a steady, tensed state during the sewing
operation.
[0021] While the present invention has been described in connection
with what is considered the most practical and preferred
embodiment, it is understood that this invention is not limited to
the disclosed embodiment but is intended to cover various
arrangements included within the spirit and scope of the broadest
interpretations and equivalent arrangements.
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