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Патент USA US3029773

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April 17, 1962
I
E. P. TURNER ETAL
3,029,763
THREAD BREAK SENSING DEVICE FOR SEWING MACHINES
Filed Aug. 3, 1959
2 Sheets-Sheet 1
(fly-‘SI
IN VEN TOR.
Edgar P. Turner and
BY
A/ber/ /V. 600k
TTORNEY
April 17, 1962
E. P. TURNER ETAL
3,029,763
THREAD BREAK SENSING DEVICE FOR SEWING MACHINES
Filed Aug. 3, 1959
2 Sheets-Sheet 2
11111441111111!
INVENTOR.
BY
Edgar P. Turner, and
Albert M Cook
23
TTORWY
“United
‘atom
(h’ice
1
3,029,763
Patented Apr. 17, 1962
2
example a buttonhole sewing machine, wherein the ma~
3,(;~29,763
chine sews a predetermined number of stitches after which
Edgar P. Turner, Watchung, and Albert N. Cook, Rer
nardsville, Ni, assignors to The Singer Manufactur
ing Company, Elizabeth, N.J., a corporation of New
the buttonhole is slit. To this end, there is mounted
in the head 11, a slitting knife 14 actuated in the usual
manner in timed sequence with the stitching cycle.
Also carried in the head 11 is the usual vertically mov
able take-up arm 15 the outer end of which is provided
Filed Aug. 3, 1959, Ser. No. 831,299
5 Claims. (Cl. 112-419)
with a thread eye 16. Secured to the front of the head
11 is ‘a face plate 17 on which is mounted a thread break
THREAD BREAK SENSTNG DE‘VECE FOR
SEWING MACHINES
Jersey
sensing member 18 having an upper horizontal limb 19
extending through a slot 20 formed in the face plate 17
and being located at a point adjacent the topmost posi
of the thread in a sewing machine.
'
tion of travel of the take-up arm 15, as shown in FIG. 1.
Prior thread break sensing devices have been objection~
Secured to the upper horizontal limb 19 is an insulating
able in that they required a sensing device in continuous 15 sleeve 21 carrying on its inner side a contact 22 adapted
The present invention relates to ‘a device for sensing
and responding to a break in or exhaustion of the supply
contact with and placing a drag on the thread at all times
during the stitching cycle. It is desirable at certain times
in the stitch forming cycle that a minimum of tension
or drag be placed on the thread. Prior devices have not
to engage the take-up arm 15 in a manner hereinafter
to be described.
Integral with and vertically depending from the upper
horizontal limb 19 (FIG. 2) is an upper vertical reach
met this requirement.
20 23 disposed on the inside of the face plate 17 and jour
An object of this invention is to provide a sensing de
naled thereon by a pair of spaced bearing elements 24
vice which places drag on the thread during that portion
fastened to the face plate by screws 25. Secured on
only of the stitching cycle at which it will not affect proper
the upper vertical reach 23 are spaced collars 26 and 27
stitch formation.
engageable with the bearing elements 24 such that verti
It is a ‘further object of this invention to provide a 25 cal movement of the thread break sensing member 18 is
single sensing device to detect breakage or e" raustion
prevented. Depending from the upper vertical reach 23
of the supply of either the needle thread or the bobbin
and connected thereto by a laterally and forwardly bent
thread.
portion 28 extending through a notch 29 in the face
The aforementioned objects are accomplished by the
plate 17 is a lower vertical reach 30 having a lower hori
present invention which is so arranged as to apply a drag 30 zontal limb or thread feeler ?nger 31 extending in the
on the thread in that portion only of the sewinc cycle
opposite direction from the upper horizontal limb 19 and
when the already formed stitch is being set and thread
lying in the path of movement of the needle thread 1‘
is being drawn from the thread supply. These two ac
extending between the take-up arm 15 and the needle 13.
tions occur as the take-up arm approaches the top of its
A forwardly bent thread retaining limb 31a retains the
stroke. During this portion of the sewing cycle the thread 35 thread t within the con?nes of the thread feeler ?nger 31.
is drawn tight by the take-up ‘and additional drag does
Normally urging the contact 22 toward the take-up
not adversely affect stitch formation.
arm 15 and into the path of movement thereof is a spring
Having in mind the ‘above and other objects that will
32 which encircles the upper reach section 23 adjacent
‘be evident from an understanding of this disclosure, the
to the portion 28. One end of the spring 32 is anchored
invention comprises the devices, combinations and ar
on the face plate by the screw 25 and the other end en
rangements of parts as illustrated in the presently prefer
circles the lower reach section 30. Limiting the move
red embodiment of the invention which is hereinafter set
ment of the upper limb 19 toward the take-up arm '15
forth in such detail as to enable those skilled in the art
is a stop plate 34 ?xed to the upper reach 23 and adjust
readily to understand the function, operation and ‘ad
able in response to turning of screw 33.
'
vantages of it when read in conjunction with the accom 45
Electrical leads 35 and 35a, leading respectively from
panying drawings in which:
the contact 22 to the low voltage control unit 36 and
FIG. 1 is a side elevational view of the head portion
from the control unit to the machine frame, form an open
of a sewing machine bracket arm having the present
circuit which when closed by engagement of the contact
thread "break sensing device applied thereto.
22 and take-up 15 is effective to energize the control
FIG. 2 is a front elevational view of the sewing ma 50 unit 36.
chine face plate.
a
FIG. 3 is a fragmentary top view of the bracket arm
head showing the position of the thread break sensing
The control unit may then transmit a visual
or audible signal indicating that the thread has broken
or the thread supply is exhausted. The control unit may
also provide for automatic stopping of the machine.
The operation of the thread break sensing arrangement
member relative to the take-up arm when the thread is
unbroken.
is as follows:
FIG. 4 is a view similar to FIG. 3, but showing the
‘When the needle thread I is unbroken and stitches are
position of the thread break sensing member when the
being formed in the conventional manner the needle
thread is broken or the thread supply is exhausted.
thread travels from its source, over a guide member 37
FIG. 5 is an enlarged side elevational view of the
through a thread tension 38, through the check spring
bracket arm head of the machine showing the relation 60 through the eye 16 of the take-up arm 15, across the face
ship of the parts as the stitch is being set and new thread
plate 17, into a thread guiding slot 39 and thence through
is being drawn from the thread supply.
the eye of the needle 13. During normal stitch formation
FIG. 6 is similar to FIG. 5 but shows the relationship
the take-up arm 15 travels in a vertical path alternately
of the parts when the bobbin thread supply is exhausted.
giving and taking up thread as the stitch formation re
Referring now to the drawings, the present invention ' quires. During this giving and taking up of thread the
is embodied in a sewing machine having a bracket arm
length of thread t extending between the take-up arm 15
10 terminating ‘m a head 11 in which there is mounted
and the material being stitched is tightened across the
a reciprocating needle bar 12 carrying at its lower end
front surface of the face plate 17 only when the take-up
a needle 13. While the application of the present in
arm moves upwardly toward its top position where it
vention is not restricted to any particular type of sewing 70 exerts a maximum tension on the thread. Thus, when
machine the invention is incorporated for purposes of
thread is eing given up the thread 1‘ merely slides or drops
illustration in a cyclically operated sewing machine, as for
over the thread feeler ?nger 31 and the thread break
3,029,763
3
sensing member 18 is urged clockwise, as viewed in FIGS.
3 and 4, by the spring 32 and positions the contact 22 on
the upper limb 19 in the path of movement of the take-up
arm 15.
thereon and including a vertically movable thread take-up
device, an electrical control unit for indicating a break in
, or exhaustion of the thread supply, switch means for
However, since the contact 22 is located ad
jacent to the topmost position of the take-up arm 15 during
the downward movement of the take-up arm 15 the con
tact 22 will not be engaged during this period of stitch
formation. As the take-up moves upwardly, particularly
energizing said control unit when the thread supply is
broken or exhausted, said switch means comprising two
movable contacts, said vertically movable take-up device
comprising one of said contacts, said switch means being
operable only when said take-up device is at substantially
the high point of its vertical travel.
as it approaches the top of the stroke, the needle thread 1
3. In combination with a sewing machine comprising a
is being drawn tight and when substantially at the top of 10
frame having stitch forming instrumentalities supported
its stroke it draws the previously formed stitch tight. Ac
thereon and including a vertically movable thread take-up
cordingly, at this time, as shown in FIGS. 1 and 3, the
device, an electrical control unit for indicating a break in
thread I is drawn upwardly in the thread guiding slot 39
or exhaustion of the thread supply, switch means for
and tightened across the outer surface of the face plate
energizing said control unit when the thread supply is
17 whereupon the tightened thread t engages the thread
broken or exhausted, said switch means comprising two
feeler ?nger 31 adjacent the retaining limb 31a and is
movable contacts, said vertically movable thread take-up
e?ective to apply a turning movement on the thread
device comprising a ?rst of said contacts, said second con
sensing device 18 to turn the limb i9 counterclockwise
tact being normally biased into the path of travel of said
against the action of the spring 32 and thereby prevent the
contact 22 from engaging the take-up arm 15.
' 20 take-up device, and means operable when said thread sup
ply is unbroken to urge said second contact from the path
In the event that the needle thread t is broken, as shown
of travel of said take-up lever as it approaches the high
in FIG. 4, this condition wiil be sensed by the thread
point of its vertical path.
feeler ?nger 31 since the thread merely drops slack and
4. In combination with a sewing machine comprising
the thread break sensing member 18 is not turned. The
a frame having stitch forming instrumentalities supported
contact 22 will then remain in its spring-urged position
thereon and including a vertically movable thread take-up
in the path of the take-up arm 15 which, when the latter
device, an electrical control unit for indicating a break
reaches its topmost position, will engage the contact 22
and energize the control unit 36.
.
In FIG. 5 there is illustrated the relative positions of the
in or exhaustion of the thread supply, switch means for
energizing said control unit, said switch means comprising
two movable contacts, said vertically movable thread
take-up arm and the contact 22 at stitch setting when the
needle thread tis unbroken and there is a supply of bobbin
thread 12 on the usual bobbin housed within the loop
taking member 49. It is to be observed that as the threads
t and b are being set'to form the lock stitch in the work
the bobbin thread b holds one end of the needle thread I 35
posed thread break sensing member carrying said second
contact, said thread sensing member mounted for pivotal
turning about its vertical axis; a spring normally biasing
?xed in the work whereby the latter is held tight and in
engagement with the thread feeler ?nger 31,. Hence, as
above described in connection with the sensing of a break
in the needle thread 2‘, the tightening of the needle thread I
applies a turning movement to the thread break sensing 40
urge said thread break sensing member about its vertical
member 18 to move the contact 22 out of engagement
take'up cor rprising a ?rst of said contacts, a vertically dis
said thread break sensing member about its vertical axis
to bring said second contact carried thereby into the path
of travel of said thread take-up member, and means to
axis in opposition to said spring when said thread supply
is unbroken.
5. In combination with a sewing machine comprising a
frame having stitch forming instrumentalities supported
with the take-up arm 15.
thereon and including a vertically movable thread take-up
As shown in FIG. 6, when the bobbin thread b is ex
device, an electrical control unit for indicating a break in
hausted the needle thread 2 is slack, since the increment
of needle thread t drawn from its source during the feed 45 or exhaustion of the thread supply, switch means for ener
gizing said control unit, said switch means comprising
ing of the work in is no longer concatenated with the
two movable contacts, said vertically movable thread
bobbin thread b. It is readily apparent that in a slack
take-up comprising a ?rst of said contacts, a vertically dis
condition the needle thread t is incapable of applying a
posed thread sensing member carrying said second con
turning movement to the thread break sensing member 13
for moving the contact 22 out of its spring urged position 50 tact, said thread sensing member mounted for pivotal turn
ing about its vertical axis, a spring normally biasing said
and the latter will contact the take-up arm 15 when it
thread sensing member about its vertical axis to bring
reaches its topmost position as shown in FIG. 6.
said second contact carried thereby into the path of travel
Having thus set forth the nature of the invention, what
of said thread take-up member, and an arm integral with
we claim herein is:
'
1. A device for use with a sewing machine for sensing 55 and extending laterally from said vertical thread sensing
member in the path of the needle thread between the
a break in or exhaustion of the thread supply, comprising
take-up and the needle responsive to the tightening of the
a. control device for indicating when said sewing thread
needle thread at that point in the sewing cycle when the
supply is broken or exhausted, a pair of electrical contacts
stitch is being set to urge said thread break sensing mem
to complete a circuit to said control device when said
thread supply is broken or exhausted, said pair of contacts 60 ber out of the path of travel of said take-up member.
meeting only when said thread supply is broken or ex
References Cited in the ?le of this patent
hausted, a ?rst ‘of said contacts being normally urged into
UNITED STATES PATENTS
the plane of travel of said second contact, and means to
urge ?rst contact out of said plane of travel of said second
1,042,602
Roberts et al ___________ __ Oct. 29, 1912
contact only during that portion of a sewing cycle when 65
1,738,142
1,742,953
2,400,529
2,868,151
Gail __________________ __ Dec. 3,
Gahlert et al. __________ __ Jan. 7,
Behrens ______________ __ May 21,
Winz ________________ __ Jan. 13,
a stitch is being set.
2. In combination with a sewing machine comprising a
frame having stitch forming instrumentalities supported
1929
1930
1946
1959
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