U.S. patent application number 12/700393 was filed with the patent office on 2010-08-19 for locking device for a bobbin case for a bottom thread bobbin.
This patent application is currently assigned to BERNINA INTERNATIONAL AG. Invention is credited to Hans Fluckiger, Niklaus Wacker.
Application Number | 20100206207 12/700393 |
Document ID | / |
Family ID | 42236367 |
Filed Date | 2010-08-19 |
United States Patent
Application |
20100206207 |
Kind Code |
A1 |
Fluckiger; Hans ; et
al. |
August 19, 2010 |
LOCKING DEVICE FOR A BOBBIN CASE FOR A BOTTOM THREAD BOBBIN
Abstract
A locking device having a connection element (11) that is
securely connected to the hook base (1) but can rotate is provided.
On the connection element (11), a coil spring (17) is supported
that is compressed after setting the bobbin case (5) on or in the
hook base (1). Through a slight tilting movement, the bobbin case
(5) or the bobbin (7) could be pushed and guided over the
connection element (11) and then held by the force of the spring
(17) in the locking position.
Inventors: |
Fluckiger; Hans; (Oetwil am
See, CH) ; Wacker; Niklaus; (Steckborn, CH) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
UNITED PLAZA, SUITE 1600, 30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
BERNINA INTERNATIONAL AG
Steckborn
CH
|
Family ID: |
42236367 |
Appl. No.: |
12/700393 |
Filed: |
February 4, 2010 |
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; D05B 57/28 20060101 D05B057/28 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2009 |
CH |
00250/09 |
Claims
1. A locking device for a bobbin case (5) for a bottom thread
bobbin (7) in a hook base (1) of a sewing machine, comprising a
receptacle space in the hook base (1) for the bobbin (7) or the
bobbin case (5) and a spindle (9), the locking device comprises a
peripheral groove (21) constructed on the spindle (9) in the hook
base (1) and a coil spring (17) located between an upper end of the
spindle (9) and the bobbin case (5), and the spring is compressed
by the bobbin case when the bobbin case (5) is set on top of the
spindle.
2. The locking device according to claim 1, wherein a connection
element (11) is provided on the spindle connected to the hook base
(1), and the peripheral groove (21) is located in the connection
element.
3. The locking device according to claim 2, wherein a flange (23)
directed radially inward and only partially circular is constructed
on the bobbin case (5) on a lower end thereof protruding into a
central borehole (13) of the bobbin case.
4. The locking device according to claim 3, wherein the flange (23)
has a crescent-shaped construction.
5. The locking device according to claim 3, wherein a cross section
of the borehole (13) between the flange (23) and a lower region of
the wall section of the borehole (13) is greater than a diameter of
the connection element (11).
6. The locking device according to claim 5, wherein the diameter of
the connection element (11) corresponds on an upper end thereof
approximately to a diameter of the borehole (13) in the bobbin case
(5).
7. The locking device according to claim 5, wherein the borehole
(13) has a cylindrical construction in an upper region thereof and
is cylindrical over about 180.degree. in the lower region with the
flange (23) and has a cylinder-barrel-shaped surface over a
remainder of the lower region, and an axis of the
cylinder-barrel-shaped surface lies at an acute angle relative to a
rotational axis of the bobbin (7).
8. The locking device according to claim 1, wherein a sleeve (31)
is located in the bobbin (7) such that the bobbin can rotate about
a central borehole (13) of the sleeve, the borehole (13) has a
cylindrical construction in an upper region and is cylindrical over
about 180.degree. in a lower region having a flange (23) and has a
cylinder-barrel-shaped surface over a remainder of the lower
region, and the axis of the cylinder-barrel-shaped surface lies at
an acute angle relative to a rotational axis of the bobbin (7).
9. The locking device according to claim 8, wherein a cross section
of the borehole (13) between the flange (23) and a tapered region
of a lower wall section b of the borehole (13) is larger than a
diameter of the locking element (11) above the peripheral groove
(21).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Swiss Patent
Application No. 00250/09, filed Feb. 17, 2009, which is
incorporated herein by reference as if fully set forth.
BACKGROUND
[0002] The invention is directed to a locking device for a bobbin
case for a bottom thread bobbin.
[0003] The bottom thread bobbin of sewing machines, especially
household sewing machines, can be stored either directly in the
hook base, wherein it is thus directly accessible, or it can also
be inserted in a bobbin case that is designed specifically for this
purpose and that is stored, for its part, in the hook base. The
present invention relates to a bottom thread bobbin supported
indirectly in a bobbin case in the hook base. The invention could
also be applied to a bobbin that can be inserted directly in the
hook base. From DE-A1 3819405 a bobbin case for rotary shuttles is
known in which the bobbin is pushed on a cylindrical bobbin spindle
that is part of the bobbin case and that is held by a securing
lever. The securing lever that is constructed as a two-arm lever is
held in two positions (open position and work position) by a
spring-loaded plate. The locking system is released by the manual
pivoting of the lever by 90.degree. into an axis-parallel position.
Then the bobbin can be lifted out from the hook base. In order to
simplify the lifting of the bobbin from the hook base, in DE-A1
19510830 it is proposed to insert a coil spring between the bottom
side of the bobbin, i.e., the bobbin flange at the bottom, and the
hook base. After release of the bobbin by the lever, this spring
presses the bobbin partially out of the hook base. At the same
time, during sewing the spring exerts a braking moment on the
bobbin, wherein this moment has a different magnitude according to
the construction of the bobbin surface and cannot be influenced.
This could impair the sewing process.
[0004] From GB-A 2149433, a bobbin holder is known in which the
bobbin is held by a spring-loaded holder spindle that can be guided
through the bobbin. The holder spindle could be brought out from
the holder in the removal position through a quarter rotation and
releases completely from the hook base together with the bobbin.
Consequently, when a full bobbin is inserted, the holder spindle
must be inserted into this bobbin and then secured. From EP-B1
1541736 a locking device for a bottom thread bobbin is known in
which, on the hook base, a locking device that can be guided
through the central opening in the bobbin is held on a spring and
the bobbin is automatically locked after pressing the bobbin down
completely into the hook base. Through a radial shifting of the
locking element relative to the rotational axis of the bobbin, the
bobbin can be detached again from the locking device. It is then
ejected by the spring carrying the locking element.
SUMMARY
[0005] The present invention provides a locking device for a bobbin
case for a bottom thread bobbin with which the bobbin case can be
locked in the hook base and can be released without activating a
catch means, which produces, in addition, an axial pushing of the
bobbin or the bobbin case from the hook base after the release.
Advantageous constructions of the invention are described in more
detail below and in claims.
[0006] Through slight eccentric pressure on the bobbin case or the
bobbin, the holding position that holds the bobbin captured in the
hook base can be released and simultaneously the partial ejection
of the bobbin case or, if a bobbin is held without a bobbin case in
the hook base, the ejection of the bobbin is initiated. The locking
of a new bobbin case or a bobbin to be inserted in the hook base is
realized through axial pushing of the bobbin or bobbin case into
the hook base until this reaches the recess in the hook base and
tilts over. Then no additional locking manipulations are needed.
The bobbin held by the locking element is not braked in any way by
the locking element, because this locking element does not contact
the bobbin with a positive fit.
[0007] The locking device according to the invention consequently
manages without a bolt, slide, or flaps. The coil spring located in
the bobbin or bobbin case represents the sole moving element,
wherein this spring secures the locking position after the locking
and causes the ejection of the bobbin or bobbin case during the
unlocking.
[0008] In contrast to known locking devices, according to the
invention, no bobbin case hinge is needed and consequently there
are no parts over the case or bobbin that could prevent a
trouble-free passage of thread. By eliminating mechanical parts,
such as hinges, there is more space on the bobbin case or bobbin
and a bobbin with a larger quantity of thread can be used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will be explained in more detail with
reference to an illustrated embodiment. Shown are:
[0010] FIG. 1 is an axial section through a hook base with a bobbin
case together with a bobbin inserted there lying above this
carrier,
[0011] FIG. 2 is an axial section through the hook base with an
inserted bobbin case directly before the locking of the bobbin case
(bobbin case still slightly inclined),
[0012] FIG. 3 is an axial section through the hook base with locked
bobbin case,
[0013] FIG. 4 is an axial section through the hook base with bobbin
case released again from the locking device, before ejection of the
bobbin,
[0014] FIG. 5 is an axial section through a bobbin with inserted
sleeve,
[0015] FIG. 6 is a horizontal section through the hook base and the
bobbin case,
[0016] FIG. 7 is a perspective view of the bobbin in FIG. 5,
and
[0017] FIG. 8 is an axial section through another embodiment of the
connection element that is molded directly on the hook base.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] With the reference symbol 1, a hook base of a hook assembly
3 is designated. In FIG. 1, a bobbin case 5 with a bobbin 7
inserted therein lies above the hook base 1. The bobbin case 5 with
the bobbin 7 is thus not yet inserted into the hook base 1. This is
a state after the replacement/filling of the bottom thread bobbin
7. In the hook base 1, a connection element 11 is placed on a
spindle 9 constructed centrally. This element is connected rigidly
to the spindle 9 but can rotate axially and can be made from
plastic or metal. The periphery of the connection element 11 can
have a cylindrical construction (no illustration) or, as shown in
the figures, it can have a shoulder-shaped neck section in the
upper region. The bobbin case 5 comprises, in the center, a
borehole 13 that has a cylindrical profile in the upper part a and
that has a cylindrical construction in the lower part b over a
partial region of the periphery of the borehole 13, e.g., over
180.degree., and the opposite region is formed by a cylindrical
section whose axis lies at an angle to the axis of the other region
(cf. FIGS. 1-4, in each, left side of the borehole 13). In the end
region of the bobbin case 5, the borehole 13 can have a closed
construction or its cross section can have a smaller diameter than
the cylindrical section a of the borehole 13 lying underneath.
[0019] On a circular shoulder 15 or a flat end face on the upper
end of the connection element 11, a coaxially arranged coil spring
17 is supported. The spring 17 is attached with its upper end on
the bobbin case 5, e.g., clamped or bonded. When the bobbin case 5
is placed on top, the upper end ring 19 of the coil spring 17
therefore contacts the bobbin case 5. Advantageously, the end ring
19 is larger in diameter than the rest of the windings. The coil
spring 17 is dimensioned such that, in the case of a bobbin case 5
locked completely in the hook base 1, the coil spring 17 is under
compressive force and, when the bobbin case 5 is released, the coil
spring 17 lifts or ejects the bobbin case 5 at least partially from
the hook base 1, in order to simplify the grasping of the bobbin
case 5.
[0020] On the lower end of the connection element 11, also called
the case carrier, a circular groove 21 is countersunk. The axial
height of the groove 21 is slightly greater than the axial height
of a crescent-shaped flange section 23 directed inward and running
over a partial region of the borehole 13 on the bobbin case 5. The
distance of the inner edge 25 of the flange section 23 relative to
the opposite, non-parallel wall section b is slightly larger than
the diameter of the connection element 11 (cf. FIG. 6).
[0021] Below, the functioning of the hook assembly 3 will be
explained in greater detail.
[0022] The bobbin case 5 equipped with a new bobbin 7, i.e., a
bobbin filled with thread, is pushed axially from the top over the
connection element 11. Here, the coil spring 17 comes into spring
contact with the upper end of the connection element 11.
[0023] A marking 29 is formed eccentrically on the end face 27 of
the bobbin case 5. The marking 29 can be coloring or a region
provided with grooves by means of, for example, a laser beam, or
can consist of a recess. For engaging or locking the bobbin case 5,
the person sewing presses with one finger approximately in the
center on the bobbin case 5 (arrow F.sub.1); for further pressing,
the bobbin case 5 becomes slightly tilted by the flange 23 provided
only over a partial region (ca. 180.degree.) on the lower end of
the borehole 13, as is visible in FIG. 2. Through this inclined
position, it becomes possible that the crescent-shaped flange 23 on
only part of the periphery can slide past the lateral surface of
the connection element 11 and can then engage in the groove 21,
when the bobbin case 5 tilts back to the horizontal.
[0024] For releasing the bobbin case 5 from the hook base 1, the
procedure is reversed, in that, a pressure according to arrow
F.sub.2 is exerted with a finger on the eccentrically formed
marking 29 and thus the bobbin case 5 tilts and the edge 25 of the
flange 23 moves out from the groove 21 and then the bobbin case 5
is lifted by the force of the coil spring 17 until it can be raised
with two fingers from the hook base 1.
[0025] In FIG. 5, a bobbin 7 is shown in the axial section that is
not supported in a bobbin case 5. So that it can rotate within the
hook base 1 during sewing, a sleeve 31 is inserted so that it can
rotate in the center of the bobbin 7. The sleeve 31 comprises, both
at the top and also at the bottom, means, e.g., a raised edge or
flange 33, wherein these means hold the sleeve 31 in the bobbin 7
axially with play. The borehole 13 in the sleeve 31 is constructed
analogous to the borehole 13 in the bobbin case 5 in the examples 1
to 4. In other words, the upper region a is cylindrical and
approximately half of the lower region b has a profile of a
cylinder-barrel surface inclined toward the axis of the bobbin case
5 (cf. also FIG. 2). The upper end of the sleeve 31 is closed and
is used as a contact for the coil spring 17 not shown in FIG.
5.
[0026] In the ring-shaped flange of the sleeve 31 lying at the top,
a marking 29 is formed eccentrically, as in the first embodiment,
in order to indicate to the operator at which point he must apply a
pressing force F2 for unlocking.
[0027] In another construction of the invention shown in FIG. 8,
the connection element 11 is part of the spindle 9, i.e., the
periphery of the spindle 9 has the shape of the periphery of the
connection element 11 in the first embodiment. The function of the
insertion or ejection of the bobbin case 5 with the bobbin 7 takes
place in the same way.
LEGEND
[0028] 1 Hook base [0029] 3 Shuttle arrangement [0030] 5 Bobbin
case [0031] 7 Bobbin [0032] 9 Spindle [0033] 11 Connection element
[0034] 13 Borehole [0035] 15 Shoulder [0036] 17 Coil spring [0037]
19 End ring [0038] 21 Groove [0039] 23 Flange [0040] 25 Edge [0041]
27 End face [0042] 29 Marking [0043] 31 Sleeve [0044] 33 Raised
edge or flange
* * * * *