US2526279A - Device for producing warning prior to exhaustion of bobbin thread - Google Patents

Description

Oct. 17, 1950 L ROSEMAN 2, 26,27

DEVICE FOR PRODUCING WARNING PRIOR TO EXHAUSTION OF BOBBIN THREAD Filed Sept. 25, 1944 6 Sheets-Sheet 1 Zmventor (Itton [QB Opt. 17, 1950 2,526,279

- L. ROSEMAN DEVICE FOR PRODUCING WARNING PRIOR TO EXHAUSTION OF BOBBIN THREAD Filed Sept. 23, 1944 6 Sheets-Sheet 2 Qttorneg Filed Sept. 23, 1944 Oct. 17, 1950 L ROSEMAN 2,526,279

DEVICE FOR PRODUCING WARNING PRIOR TO EXHAUSTION OF BOBBIN THREAD 6 Sheets-Sheet 5 I attolllell Oct. 17, 1950 RQSEMAN 2,526,279

DEVICE FOR P RODUCING WARNING PRIOR TO EXHAUSTION OF BOBBIN THREAD Filed Sept. 23,1944 6 Sheets-Sheet 5 Gttorneg Z ISnnentor Oct. 17, 1950 L ROSEMAN 2,526,279

. DEVICE FOR P RODUCING WARNING PRIOR TO EXHAUSTION 0F BOBBIN THREAD Filed Sept. 23, 1944 6 Sheets-Sheet 6 10/ 102" Illllh 94 I %j/ 13/ 2 lnventor Ctttomeg Patented Oct. 17, 1950 DEVICE-FOR PRODUCING WARNING PRIOR TO EXHAUSTION OF BOBBIN THREAD Leo Roseman, Newark, N. J.

Application September 23, 1944, Serial 0. 555,534

This invention relates in particular to sewing machines and other types of machines that include bobbins, shuttles or the like, and especially contemplates a novel and improved method of and mechanism for automatically effecting a warning, or for stopping or preventing starting of r the machine, or for performing some other operation or producing some result upon or prior to exhaustionof the bobbin thread. I

It is well known that in the ordinary operation of sewing machines, especially in commercial production of sewed articles, the bobbin thread runs out or becomes exhausted, without previous warning to the operator, about every ten to twenty minutes, and frequently before the sewing of the article has been completed. The exhausted bobbin must be replacedfwhich is often troublesome, especially when the work or folding or guiding attachments overlie the bobbin cases; it being difficult to remove such attachments before the sewing operation on an article is completed; and, moreover, the s titching is interrupted which leaves loose ends'on the threads to be trimmed and causes a patched appearance in the stitches at the point where stitching was interrupted and resumed.- Furthermore, in many instances when the bobbin thread runs out before the line of stitching is completed, it is necessary to remove the stitches thathave been formed and to start another line after a new supply of bobbin thread has been provided.

Not infrequently, the bobbin threadruns, out but the needle thread on the upper surface of the work appears as if the stitching were normal, so that incomplete stitching continues for long periods without discovery that the-bobbin threadis exhausted, which requires repeating the sewing operation and causes substantial loss of time.

It is, of course, desirable that-the stitching should not be interrupted and that, if possible, bobbin thread replacements should be made'after sewing of one article has been complte'dan'd be; fore sewing of another hasbeen started; ou

special work the operator often 'r'emovesthebob bin before the stitching of an article is completed to ascertain whether enoughl thread remains to complete the sewing and thereby avoid such interruption in the line of stitches. This is troublesome and time-wasting procedure. Myinvention overcomes these difficulties and disadvantages 21 Clai ms.' (0141 2-218) 2 a a simple and reliable methodand mechanism or the character described wherein a change in or variation of, or addition to the bobbin thre'ad shall be made artificially at a predetermined distance from the end of thread to effect or control the production of the warning or the stopping of the machine, or some other operation or result at a predetermined time prior to the exhaustionpf the thread and soon enough beforecompletion of the sewing operation to ensure adequate thread to finish the stitching.

Further objects are to provide mechanisms which shall be adaptable to many different types of sewing machines without change in the fundamental structure of the machines, and to provide such a mechanism which shall embody novel and improved features of construction wherein said change in, variation in' the condition of, or addition to the bobbin thread shall cooperate with the tension spring on the bobbin case to produce a certain result, for example to actuate an elec tric circuit for operating a signal or for controllingstop mechanism for the machine.

A further object is to provide a mechanism of this character wherein said cooperation of said bobbinthread with said tension spring shall vary the tension on the bobbin thread, and means responsive to said variation in tension shall be pro vided to produce a certain result, e. g. operate a signal, etc.

.It'is known that a change in tension on, the bobbin thread will cause a change in the amount of the'needle thread used in lock-stitch sewing machines. In my Patent No. 1,647,1l8, I have de scribed means responsive to variations in feeding movement of the needle'thread for controlling an electric circuit, to operate a signal, when theamount of thethreadbeing used varies during a'sewing operation.

Another object of my invention is to utilize such means responsive to variation in the amount of the needle thread consumed, in combination with said mechanism wherein the tension on the bobbin thread is changed by cooperation of the bobbin thread and the bobbin tension spring, whereby to operate a signal, etc H In' sewing machines including such a combina: tion and wherein the speed of operation may be suddenly and often changed by manual control, the amount of the needlethread consumed, may be varied by such speed changes during normal operation so as to produce a false signalgand ac cordinglyanother object of my inventio n is to provide novel and improved means for compensating for said sudden-speed changes and thereby to prevent false signals.

A further object is to utilize in combination with said mechanism that is actuated by the bobbin thread, means for preventing starting of the sewing machine or another machine after said mechanism has been actuated and until said mechanism has been restored or reset manually or automatically to its initial normal condition, for example, upon replacement of the exhausted bobbin and resetting of the tension spring, whereby to ensure, for example, that the machine will not be accidentally started without adequate bobbin,

thread.

Other objects, advantages and results of the invention will be brought out by the following description in conjunction with the accompanying drawings in which Figure 1 is a front elevational view of a sewing machine having applied thereto a mechanism embodying my invention for warning of the approaching exhaustion of the bobbin thread and for preventing starting of the machine until it is in proper condition for operation.

Figure 1a is a wiring diagram of the electrical circuit forming a part of the said mechanism.

Figure 2 is a fragmentar horizontal sectional view on the line 22 of Figure 1.

Figure 3 is a side elevational view of a part of a stop mechanism observing the same from the line 33 of Figure 1.

Fi ure 4 is a transverse vertical sectional view on the line 44 of Figure 3.

Figure 5 is a similar view on the line 55 of Figure 3.

Figure 6 is anenlarged fragmentary top plan view of the bed portion of the machine observing the same from the line 6-6 of Figure 1, and showing the slide cover plates removed.

Figure '7 is a front elevational view of the parts sho n in Figure 6.

Figure 8 is a bottom plan view thereof.

Figure 9 is a verti al longitudinal sectional view on the line 99 of Figure 6.

Figure 10 is an enlarged detached perspective view of the bobbin case.

Figure 11 is an edge view of the bobbin case, observing t e same from an angle slightly different from that shown in Figure 10.

Figure 12 is a similar view showing the tension spring removed.

Figure 13 is an enlar ed fragmentary sectional view of the ri ht-hand bobbin shown in Fig re 6, taken approximately on the line !3-!3 of Figure 11 and s owing t e normal positions of the feeler of the electrical switch mechanism and the thread tension spring therefor.

Figure 14 is a similar view showing the positions of the feeler and the tension spring after the latter has been actuated by a knot in the bobbin thread.

Figure 15 is a front elevational view of aosewing machine having another form of my invention applied thereto.

Figure .16 is a vertical sectional view on the line |6l6 of Figure 15.

Figure 1'7 is a horizontal sectional view on the line "-41 of Figure 15.

Figure 18 is an enlarged vertical sectional view through one of the switches of the electrical signaling circuit.

v Figure 19 is a wiring diagram of the electrical signaling circuit controlled by the needle thread.

Figure 20 is an enlargediragmentary side elevational view of the portion of the machine containing the bobbin and sewing hook.

Figure 21 is an elevational view taken from the line 2 l2l of Figure 20.

Figure 22 is an enlarged detached perspective view of the bobbin case.

Figure 23 is an enlarged vertical sectional view on the line 23-23 of Figure 20, showing the nor-- mal position of the tension spring on the bobbin case.

Figure 24 is a similar view showing the position of the tension spring after the latter has been actuated by a knot in the bobbin thread.

Figure 25 is a view similar to Figure 20 showing a modification of the feeler and circuit closing mechanism especially designed for use with the type of sewing machine shown in Figure 15, but wherein the tension of the bobbin thread is not varied.

Figure 26 is an elevational view taken from the plane of line 26-426 of Figure 25.

Figure 27 is a like view taken from the plane of line 2T21 of Figure 25.

Figure 28 is a bottom plan view of the parts shown in Figure 25.

Figure 29 is an enlarged vertical sectional View through a bobbin case showing the normal position of the feeler and of the tension spring onthe bobbin case.

Figure 30 is a similar View showing the position of the tension spring after it has been actuated by theknot in the bobbin thread.

Figure '31 is a wiring diagram of the electrical signaling circuit controlled by the feeler.

Figure 32 is an enlarged longitudinal vertical sectional view through two pieces of material joined together by a lock stitch such as is formed by the machines hereinbefore mentioned.

Figure 33 is a schematic view, with portions broken away and shown in section, illustrating another form of bobbin and another manner of actuating the tension spring and circuit closing mechanism by the knot on the bobbin thread, the parts being shown in their normal positions.

Figure 34 is a similar view showing the manner of operation of the tension spring and circuit closer by the knot on the bobbin thread, and

Figure 35 in a view similar to Figure 33 show ing another modification of the invention.

Referring particularly to the form of the invention shown in Figures 1 to 14 inclusive, for the purpose of explaining the principles of the invention i have shown it in conjunction with a known type of "Singer sewing machine, particularly the machine generally known as 112-w140, and for simplicity many parts of the machine have been omitted while other parts are only schematically illustrated because they are not essential to an understanding of my invention. It should be understood that no change of structure in the sewing machine is necessary, except in the bobbin tension spring hereinafter described.

, Generally describing the machine it includes a bed plate I which is shown as mounted on a table or bench 2 and which has a goose neck or main frame 3 in which is journaled adrive shaft 4 which is driven by a belt and pulley connection 5 from a drive shaft 6 which is adapted to be connected and disconnected from an electric motor 1 through a suitable clutch 8 which is controlled by a lever 9 which is normally spring influenced upwardly in known manner and is pulled downwardly through a pull rod H3. This pull rod In is pivotally connected at H to a V the floor beneath the machine so that upon oscillation of the treadle the rod-will be "pulled down and permitted to rise-so that the clutch 8 may be engaged and disengaged to start and stop the machine respectively. V p Mounted in the goose neck 3 is thread take-up lever l4 and tension device l5',=an'd a needle bar l4 which carries two needles each to cooperate with a bobbin l6 which is mounted in a bob-bin case I! in the usual manner; Between the bobbin cases is a known feed do'g'l Scooperating with a presser foot I9 for feeding 'work under. the

needles.

As usual, the needle bar isdriven from the shaft 4, and this shaft also. has a belt'and pulley connection with a shaft 2| journaled on the bed plate of the machine and having a helical gear 22 for each sewing hook'23 which is mounted on a shaft 24 journaled in the saddle 25 and carrying a helical gear 26 meshing'with the corand lever connection 29 with the dog [8 for moving the latter up and down.

Now, referring more particularly to the novel features of my invention, the bobbin cases H remain stationary during operation of the machine and each has rotatably mounted therein a bobbin IS on which is Wound the bobbin thread 36. The bobbin is removable and the bobbin case has a central spindle 3i on which the bobbin is rotatable. The bobbin case also has a slot 32 in its side walls through which the thread 36 from the bobbin is'pulled-outwardly and between a portion 33 of the outer surface of the bobbin case and atension spring 34 so that said tension spring frictionally presses the thread between itself and the bobbin case to create tension on the thread. The threadis led outwardlyfrom beneath the tension spring into another opening 35 which is partially overlaid by the tension spring. 7

The tension spring is mounted on the case for longitudinal movement and to be'actuated by a knot or protuberance 36 on the bobbin thread at a predetermined distance from the inner end of the thread. More specifically, the spring has a longitudinal slot 3'l'through which extends a guide rib 38 on the bobbin case, and the spring is held against displacement by a headed screw 39. The bobbin case has an extra deep thread guide groove 46 leading outwardly from the slot 32 to permit free passage of the knot,and the tension spring has an opening 4| normally overlying the outer end of said guide groove so that as the bobbin thread is pulled from the bobbin the knot 36 will engage the edges of the opening 4! and pull the tension spring'lo-n'gitudinally of itself or circumferentially of thebobbin case until the knot reaches the opening 35 in the case,

whereupon the knot will become disengaged from the opening -41 and the thread willcontinue v to move without affecting the tension spring.

Movement of the tension spring with the knot continues until the knot is freed from the open-f The portion of the tension spring rearoutlet opening 35, so that; the normal tension o-n v the bobbin thread is maintained or unchanged.

For normally yieldingly holding the tension spring against movement by the thread the spring may have a resilient portion 42 provided with a stud or protuberance 43 to snap into and out of a depression 44 in the rib 38 on the casing, so thatwhen the stud 43 is in said depression 44, the spring will be yieldingly held against movement but can be moved under the tension on the bobbin thread when the knot 36 engages the hole 4|. To prevent the bobbin spring from being pulled away from the bobbin case in such a manner as to relieve the tension on the thread the spring may have a finger 45 slidable beneath a guide flange 46{ on the bobbin case. v

In accordance with this form of the invention, the knot 36 will be formed in the thread at a predetermined distance from the end thereof which isinitially wound on the bobbin l6, that is, the terminal end, so that while the thread is Wound on the bobbin and the bobbin is in use on a machine,- the tension spring will be actuated as .above described at a predetermined time prior to the total removalof the thread from the bobbin, 1. e. prior to exhaustion of the bobbin thread. As shown, the spring 34 of each bobbin case has a ledge 46 which when the tension spring is in its normal position during operation of the machine as shown in Figures 6, 10 and 13 is frictionally abutted by one end of a feeler 4'1, the other end of which is connected to a pivot rod 46 which is rotatably mounted in a bracket 49 secured to one arm 50 of a hanger which includes a box-like head portion 5| which conveniently may be secured to the bed plate ,of the machine by one of the screws 52 by-which the hook shaft saddles-25 are mounted on the bed plate.

The pivot rod 48 is normally actuated by a sprin 53 to hold the feeler 41 in contact with the bobbin tension spring, with a slight pressure which will permit the needle thread loop to pass between the feeler and the tension spring ateach; stitch and without affecting the sewing operation in any manner. The pivot rod '48 also carries a switch arm 54 which is adapted to cooperate with a contact screw 55 which is mounted uponthe bracket 49 and insulated therefrom by a strip of insulation 56'. During normal operation of the'machine each feeler 4'! ,is held in engagement with its respective tension spring, and each switch arm 54 is held in spaced contact with the screw. 55. In accordance with theinvention, this operation maybe utilized for producing any desiredresultor for performing any desired operation, such as closing the elec-- trical; circuit of a visible or audible signal, or

closing the circuit through automatic stop mechanism for the machine As'shown, both a visible signal and a mechanism' which will prevent starting of the machine .after it has once been stopped by the operator following the warnin given by the signal, are

I provided.

More specifically describing the mechanism, the pull rod I!) has a laterally projecting shoe 56 thereon and a starting control lever 51 is pivotally mounted atone end as at 58 on the bench 2 and has a lug 59 which normally is located under the shoe 56 to prevent the pull rod from being pudled downwardly in such a manner as to engage the clutch 8 and start the machine. A compression spring 69 normally holds the lever in this position against a stop member 60.

In order to start the machine it is necessary to swing the starting control lever 5? against the influence of the spring 60 to move the lug 59 from beneath the shoe 56, which can be conveniently accomplished by swinging a knee-lifter 51' which is generally attached to a sewing machine for liftin the presser foot by use or" the operators knee. The lever 51 is releasably held in this position by engagement of a spring actuated latch bolt 8| carried by the lever, with a latch tongue 62 which is pivotally mounted in a fixed casing 63 and normally is influenced into latching position by a spring 64. The latch tongue is normally locked in latching position by a looking lever 65 which is controlled by a detent 66 that is in turn actuated by an electromagnet 61 for releasing the locking lever 65 (see Figures 3, 4 and 1a). This electromagnetic latch mechanism may be of any suitable construction, for example such as is embodied in known types of electromagnetic door openers.

Mounted on a suitable bracket 88 on the bench 2 is an insulating switchblock 69 having two terminal posts 1!] and H to each of which is connected a blade one of which, 12, is rigidly connected by an insulated cross-piece 13 tothe other switch blade 84. On the switch block 69 are also mounted two contact elements 15 and 16 to cooperate with the respective blades l2 and I4, and both of these two contact elements are'connected to one terminal of the electromagnet 61, the other terminal of which is connected to one terminal of a low-voltage source of electricity H the other terminal of which is connected to one terminal of a main switch '18 which may be grounded on the bed plate of the machine. Mounted on a bracket is at the side of the switch blades 12 opposite the switch block 89 is a block of insulation 80 in which are mounted two adjustable contact screws 8| and 82. One of these screws is connected toone terminal of a signal lamp 83, corresponding to the left-hand bobbin I6, while the other screw 82 is connected to one terminal of a lamp 84 which corresponds to the right-hand bobbin [6. The other terminals of the lamps are connected together and to the source of electricity by a wire 85. The terminals 10 and H of the switch are connected respectively to the contact screws 55 corresponding to the respective bobbins. The bobbins are of course grounded on the bed of the machine as are also the feelers 51, pivot rods 48 and switch arms 54.

In operation, when both bobbins are filled and the machine is at rest, the starting control lever 5? is in the position shown in Figure 2 so as to prevent starting of the machine by manipulation of the treadle. In this position the switch blades 72 and M are influenced into contact with the screws 8! and 82 by a spring 86 and the electromagnet 6'! is deenergized. Before starting the machine, the exhausted bobbin must be replaced and the bobbin tension spring must be reset to its normal position. Then the operator swings the lever 51 by pressure on the knee-lifter to cause the latch bolt iii to engage the latch tongue 52 and thus hold the lug 59 out of the path of the shoe 56, so that the operator through the treadle l2 may control the starting, stopping, and the speed of the machine at will. As the lever moves, it engages the cross piece of insulation 13 on the switch so as to actuate the switch blades 12 and 14 into engagement with the contact members 15 and 16.

During operation of the machine, the bobbin thread is withdrawn from the bobbin and interlocked with the needle threads 81 to form lock stitches as shown in Figure 32. When the knot 36 of either bobbin thread actuates the corresponding bobbin tension spring 34 as above described, the corresponding switch arm 54 will be actuated into contact with its screw 55 so as to close the circuit. Thereupon the electromagnet 61 will be energized to release the lever 5'1, where- 5 upon the corresponding signal lamp 83, 84 will be lighted. The machine will continue to operate and the lug 59 will abut the side of the shoe 56 until the operator deliberately manipulates the treadle to raise the pull rod to stop the machine.

As a rule, the knot will be located in the thread so that there will be adequate thread on the bobbin to finish the sewing operation, i. e., to stitch to the end of the article being sewed, after the signal has been produced, and operation of 1' the machine usually will be continued until the end of the article is reached. This avoids interruption of stitching and ensures a minimum of waste of thread.

When the pull rod Ill is raised to stop the machine, the shoe 55 thereby is moved above th lug 59 and then the lever 5'! will be moved farther under the influence of the spring 60 so as to locate the lug 59 under the shoe and prevent accidental starting of the machine. It of course, possible for the operator to deliberately push the lever 51 and disengage the lug from the shoe so as to permit operation of the ma chine, but the electromagnet 6'! will become energized so that the latch tongue 62 will not hold the lever 51 and this condition will continue until the bobbin tension spring 34 has been reset to open the corresponding switch 54, 55, which ordinarily will not be done until after the bobbin has been replaced. However, if the operator desires to continue the operation of the machine for any purpose before the bobbin has been replaced and without holding the starting control lever, she may simply open the main switch ?8 which will prevent energization of the electromagnet 67 and thereby permit the starting lever to be locked in the position to permit starting and operation of the machine.

It should be pointed out that the use of the presser foot knee-lifter for actuating the starting control lever 51 is especially convenient. When the machine stops, generally it is necessary to adjust the work before starting again, and the presser foot is lifted, by swinging the kneelifter to the right in Figure l, which at the same time sets the starting control lever. This one simple movement of the knee-lifter performs two operations at the same time and leaves the operators hands free for adjusting the work. After the control lever has been set, further movement of the knee-lifter Will operate only the presser foot.

Another form of the invention is shown in Figures 15 to 24 where the production of the warning is controlled by variations in the tension on the bobbin thread. For convenience, the invention is shown in conjunction with a ZOY-w-l Singer sewing machine which includes the usual bed from which projects the usual goose neck 9| in which is journaled the drive shaft 92 which drives known mechanism 93 through known shaft 92.

was

means, for oscillating the needle bar which has the usual needle 94 to produce zig zag stitching. Cooperating with the needle is a bobbin 95 which is inserted in-a. bobbin case havingthe usual base 99 and a removable cover or cap 91 which is separably connected to the base by a latch 98. The usual sewing hook 99 cooperates with the bobbin thread I and the needle thread IOI in known manner and i driven by beveled earing I02 mounted on the underside of the bed 90. The beveled gearing I02 is driven by a shaft I03 journaled on the bed of 'thejmaohine and having a belt and pulley connection I04 with the drive Mounted, on the shaft I03 is a tubular shaft I95 which has the usual eccentric and connecting rod connection I06 with the drive shaft 92 and is also connected at I03 to thefeed dog I04 of the machine for moving the latter up and down. A rocker shaft I01 is connected to the feed dog to reciprocatethelatter and has'the usual eccentric and connecting rod connection I08 with the drive shaft 92. As hereinbefore mentioned, all of these parts of the machine are old and well known and are only schematically illustrated.

The bobbin case 91 has the usual opening I09 through which the thread is drawn outwardly over the outer surface of the case cover beneath a tension spring H0. The case cover also has a second opening III through which the thread is drawn inwardly from the tension spring and thereafter threaded outwardly through a guide opening I I 2.

One end of the tension spring I I0 has a slidable connection with the bobbin case cover which includes a longitudinal slot H3 in the spring slidable upon a rib II4 on the case cover, andthe spring is held in the case cover by a headed screw I Q5. The other and free end of the tension spring has a, shoe II6' which normally bears upon the thread to create the necessary tension but which provides a shoulder II1 for engagement by a knot or other protuberance II8 on the bobbin thread as the thread is pulled from the bobbin so that the tension spring will be moved with the bobbin thread and knot until the knot approaches the opening III; in the bobbin case, whereupon the knot will become disengaged from the spring and the shoe I I6 will release the tension on thethread.

Means responsive to this change in tension is provided for producing a desired result, for example, to operate a signal. This means is similar to that shown in my Patent N0. 1,647,148 but is more sensitive and adjustable and includes a centrifugal governor having a vertical shaft I3I journaled in a frame I32 on the goose neck 9I and having, apair of weighted arms I33 pivotally connected to a collar I34 on the shaft and also pivotally connected by links I35 to a disc I36 which is vertically slidable on the shaft and constitutes one element of an electricswitch, the other element of which is a roller I31 mounted on the superframe I32 in insulated relation thereto. Also, rigidly connected to the shaft I3I is a spool I38 around which passes one or more turns of the needle thread IOI between the needle and a tension device, I38 which controls the tension on the thread from the source of supply such as the spool. With this construction when the machine is in operation the needle thread IOI is inter-' locked with the bobbin thread I00 to form lock stitches as shown in Figure 32, and as the needle thread is pulled through the machine it rotates the centrifugal governor shaftI3I so as to raise '10 the weighted arms I33 by centrifugal action and elevate the disc I30 out of contact with the roller I31. Should the amount'of the needle thread consumed decrease, for example by a decrease in tension in the bobbin thread as shown at X in Figure 32, the speed of rotation of the governor shaft I3I will decrease so as to allow the disc I36 to descend and contact with the roller I31. Con versely, an increase in tension on the bobbin thread will cause an increase in the amount of needle thread consumed as shown at Y in Figure 32, which in turn will increase the speed of rotation of the governor shaft, so that by placing contact roller I31 above the disc I36, the disc will contact the roller upon an increase in tension on the bobbin thread.

If desired, the disc I39 and roller I31 may be connected in circuit with a signal lamp and a source of electricity to indicate when the tension in the thread varies as above described, especially where the machine is automatic and operates at substantially uniform speed. I

Where sudden and large variations in the speed of the machine occur, for example when the machine is manually controlled by a treadle and a clutch, I provide mechanism for ensuring substantially uniform normal speed of operation of the governor shaft I3I regardless of variations in speed of the machine, so as to avoid false signals. This mechanism is shown as comprising a worm I38 on the machine drive shaft 92 with which meshes a worm gear I39 ona vertical countershaft I40 which is journaled in the superframe I32. The upper portion of this shaft is tubular and has vertically slidable therein asecondary shaft I4! which is connected by a pin I42 extending through a slot I43 in the shaft I40 to a collar I44 which is vertically slidable on said shaft I40. Said collar is pivotally connected by links I45 to weighted levers I46 which are pivotally connected to a collar I41 fixed on the shaft I40, so that variations in speed of rotation of the shaft I40 will cause the weighted levers and consequently the shaft I4I to be raised and lowered. In order to prevent the governor shaft I3I from being materially affected by changes in speed of the machine; in other words, to ensure that the shaft I3I shall operate at substantially uniform sp ed, regardless of the speed of the machine, the spool I38 is made approximately conical and the thread is moved lengthwise of the spool as the speed of the machine changes. For example, upon an increase in the speed of the machine, the thread will be moved from a smaller to a larger diameter of the spool while upon a decrease in speed of, the machine the thread will be moved from a larger diameter to a smaller diameter. Of course, the spool will not be exactly conical, but the surface thereof will be especially shaped to conform to the variable extent of movement of the collar I 44 for different speeds of the machine,.it being known that the weighted levers and collar I44 will have smaller movement for each increment of increase in speed, the largest movement being during a change from the lowest to a slightly higher speed. 1 V I y e For the purpose of moving the thread onthe spool I38 and to make movement thereof easy and uniform, I preferably utilize an idler spool I49 which is identical with the spool I38 butarranged in upside down relation thereto and provide a thread guide mechanism cooperating with said two spools, which includes a frame having ,a top piece I50 mounted for vertical movement in guide slots I5I inthe superframe.

Between the spools the frame has an arm I52 which has a horizontal thread guide slot I53 and at the side of each spool opposite said arm is an arm I54 which has a thread guide hole I55. The needle thread passes through said guide holes and guide slot and once or twice around each of the spools I38 and I59, over a guide pulley I56, through the usual guides and tension device on the machine, and thence to the needle.

For moving the frame I59 up and down to guide the thread longitudinally of the spools, I have shown a cam shaft 156 which has a pair or cams I59 underlying the cross-piece I59 of the thread guide frame, and said shaft has thereon a pinion I59 which meshes with a straight rack bar I68 slidably mounted in the guide I6I on the superframe. The rack bar I68 has a pin and slot connection I52 with a lever I63 which is pivotally mounted intermediate its ends at I64 on the superframe and has its other end fitted in a grooved collar I65 fixedly connected to the shaft MI, sothat as said shaft I iI moves up and down, therack bar I66 will be reciprocated to rotate the cams I59 and move the thread guide frame. Obviously, as the shaft I iI moves upwardly due to an increase in speed of the shaft I66, the thread guide frame will be moved downwardly to guide the thread to a larger diameter of the spools I38 and I59.

The disc I36 of the governor is electrically example a bracket arm I1I connected to the superframe I32. The contact rods I69 are normally influenced into an opening I12 in the casing I16 at opposite sides of the plunger I68 so that 'as the plunger moves into said opening, it will contact both rods I69 and close the circuit. Normally the plunger I68 is in the position shown in Figure 18 to open the circuit, but when the machine starts the plunger is moved upwardly between the two rods 169 to close the circuit.

As Will be understood from the foregoing, when w the machine starts in operation, the disc I36 will be separated from the roller I31 so that normally there will be no signal. However, upon a reduction in tension of the bobbin thread due to engagement of the knot M8 on the bobbin thread with the bobbin tension spring III), the speed of rotation of the governor shaft I3I will be reduced so as to cause the disc I36 to contact with the roller I31, close the circuit and energize the signal I61. While it is not important, it will also be understood that should the needle thread or bobbin thread break, the signal will be operated in the same way.

After the signal has been operated, the operator may continue the sewing operation to the end of the article being sewed.

In Figures 26 to 31 inclusive is shown another form of feeler and circuit control mechanism which is designed for machines of the type shown in Figure 15, but where it is not desired to change the tension of the bobbin thread. The bobbin case cap I85 has a slot I'86 in its side walls through which the bobbin thread is pulled outwardly between the free end of the tension spring I81 and outersurface of the bobbin case l2 and thence outwardly from beneath said spring over a hole I88, this structure being in general similar to that shown in Figures 13 and 14.

The tension spring has a slidable connection with the bobbin case cover, which includes a slot I89 into which p'rojects a rib I90 on the case cover. Said cover has a thread guide groove I9l leading outwardly from the slot I86 and the tension spring has an opening I92 similar to the opening 4| to be engaged by a knot in the bobbin thread for moving the tension spring in the same manner described in connection with Figures 13 and 14.

Said movement of the tension spring controls the operation of a circuit closer which includes a feeler that may be a metal strip or wire having a curved finger I'I9 carried at one end of an arm I20 which is rigidly connected to and laterally projects from a rotatable shaft I2I journaled in the arms of a U-shaped bracket I22 which is carried by a hanger I23 that is secured by a screw I23 on the bearing I24 of the hook operating shaft. This affords a simple manner of fastening the prefabricated attachment on one ordinary type of sewing machine without any substantial modification of the machine. Connected to the shaft I2I also, is a switch contact arm I25 which cooperates with a contact screw I26 mounted on a plate I21 which is secured to th bracket I22 in insulated relation thereto.

When the bobbin and tension spring are in their normal positions as shown in Figure 28, the end of the tension spring opposite the hole I92 projects from a ledge on the bobbin case cover and the feeler finger [19 engages said end of the tension spring and is held in spaced relation to the bobbin case cover thereby. Also the switch contact arm I25 is held in spaced relation to the screw I26, a tension spring I28 being provided for influencing the shaft I2I to hold the feeler wire and the switch contact arm in said positions. When the tension spring I81 is actuated by the knot on the bobbin thread, it is pulled from beneath the feeler wire which is thereby permitted to move toward the bobbin case cover, and this movement also causes the contact arm I25 to engage the screw I26.

The switch I25, I26 may be connected in any suitable electrical circuit for producing any desired result, or the arm I25 might be utilized for mechanically operating a part, e. g. a mechanical signal, but as shown in Figure 31, the switch is connected in circuit with a signal lamp I39 and a source of electricity I3I' so that when the switch is closed the lamp I3w will be energized to indicate that the knot on the bobbin thread has reached the tension spring, for example, to indicate that the bobbin thread is near exhaustion.

Another modification of the invention is shown in Figures 33 and 34 where the bobbin tension spring I13 has one end rigidly connected to the bobbin case I14 as usual and its free end adapted to be pushed upwardly away from the bobbin case by a knot or other protuberance I15 on the bobbin thread I16 as the latter is pulled from the bobbin. Normally a feeler I11 may rest upon the tension spring I13 and be connected to a switch contact arm I18 so as to hold the latter in spaced relation to a contact screw I19, and thus when the bobbin spring I13 is actuated by the knot said feeler lever I11 will be oscillated to close the switch I18 and I19 which may be connected in for example a signal circuit as hereinbefore described. As shown, the feeler 13 arm I11 is shorter than the switch arm I18 so that the small movement of-the former is magnified at the free end of the switch arm.

Instead of utilizing a knot or some artificial protuberance on the bobbin thread, the thread may include two or more sections I80 and l8l of different diameters as shown in Figure so that as one section moves from beneath the bobbin tension spring |82 and another moves under said tension spring, the spring will be moved to cooperate, for example with a feeler lever as above described. Of course, also, the variation in diameter of the bobbin thread will vary the amount of needle thread consumed, so that, for example, a signal could be effected by sensitive governor mechanism shown in Figures 15-17.

A groove I93 of a depth or width greater than the diameter of the thread section of smaller diameter but less than the diameter of the other section, may be provided in the outer surface of the bobbin case beneath the tension spring, so that the section of larger diameter will project out of said groove farther than the section of smaller diameter, whereby normal tension on the thread will be maintained while the larger section is passing along said groove and the tension will be reduced when the smaller section reaches the groove; and a signal could be effected under control of this change of tension by use of a sensitive governor mechanism like that shown in Figures 15 to 17, as described.

Furthermore, it will be understood that other devices which are responsive t changes in the bobbin thread tension, may be used instead of that shown in Figures 15 to 17. If desired, the change in the character of the condition of the bobbin thread may be produced by applying to the thread a bead or a drop of a plastic composition or by Waxing the thread.

During the formation of lock stitches, if the bobbin thread tension is decreased slightly, the bobbin thread is drawn by the needle thread to the upper surface of the work being sewed, as shown at X in Figure 32, and accordingly if the thread has a section of different color adjacent to the end thereof when said colored section reaches the work, the stitches formed thereby will be clearly visible and thus indicate the approaching exhaustion of the bobbin thread.

Furthermore, it will occur to those skilled in the art that instead of having the longitudinally or circumferentially slidable bobbin tension spring, the bobbin thread might actuate a Swinging shoe so as to wedge the latter under the tension spring and reduce the tension on the bobbin thread. Also the tension spring itself might be made to swing laterally under influence of the knot in the bobbin thread.

In certain types of sewing machines, the shuttle or hook body has a portion whichv projects beyond the bobbin case, and a feeler such as hereinbefore described could not be used because it would interfere with rotation of the hook and formation of stitches or would be damaged by the hook. In such cases, I contemplate using a feeler which reciprocates or oscillates in timed relation to rotation of the hook so as to withdraw from and contact with the tension spring periodically as the hook moves into and out of position between said feeler and said tension spring.

In som cases, it may be desirable to permit greater variation in the adjustment of the bobbin tension spring to regulate the bobbin thread tension than is possible with the structures heretofore described, and for that. purpose I may utilize interchangeable tension springs having different strength or tension.

While I have shown and described several different forms of invention in connection with several different typesof machines, it should be understood that this is primarily for the purpose of illustratin the principles of the invention and that the construction of the invention might be widely changed and the invention may be utilized in conjunction with other types of machines, all within the spirit and scope of the invention.

The terms wound thread or wound bobbin thread as used in the appended claims are intended to include a quantity of thread. or the like wound upon itself, or, thread wound upon a simple core, or thread wound upon a core having a flangeat one end only, or thread wound upon a spool having aflange at each end; and also said terms include shuttles and similar devices. The phrase indicating means in said claims is intended to include the signal lamps or other signal devices as well as the mechanism for stopping the machine and means for performing some other operation or producing some result.

What I claim is:

1. The combination of a sewing machine having-a wound bobbin thread which is unwound during operation of said machine, a bobbin case for said bobbin, a mechanism to be actuated at a predetermined time during operation of said machine, and a deviceon said bobbin case for controlling actuation of said mechanism, said bobbin thread having means to cooperate with said device for initiating actuation of said mechanism. v

2. The combination of a machine having a wound bobbin thread which is unwound by and during operation of said machine, an electric circuit controller to be actuated at a predetermined time during operation of said machine including a part adjacent to the path of movement of said thread as the latter is unwound, said thread having means at a predetermined portion of its length to engage said part for initiating actuation of said circuit controller, and electrically operated mechanism connected in circuit with and controlled by said circuit controller.

3. Thecombination of a machine having a wound bobbin thread which is unwound by and during operation of said machine, a bobbin case having a thread tension spring movably mounted thereon, said thread having means at a predetermined portion of its length for momentarily moving said tension spring as said thread is unwound, an electric circuit controller actuated by said tension spring upon said movement thereof, and an electrically operated device connected in circuit with and controlled by said circuit controller.

4. A bobbin case having a thread outlet opening, and a part bodily movabl mounted on the exterior of the case in relation to said opening such that said part normally is stationary during withdrawal 'of normal thread, but will be momentarily engaged and moved by engagement therewith of a protuberance on said thread.

5. A bobbin case having a thread outlet opening, and atension spring movably mounted on the exterior of said case in relation to said outlet opening such that thread withdrawn from said case slides and is frictionally gripped between'said spring and said case and said spring is normally stationary but will be momentarily 15 engaged and moved by a protuberance on said thread.

6. The combination set forth in claim 2 with the addition of means manually actuated for controlling starting and stopping of said machine, and wherein said mechanism includes means for preventing operation of said manually actuated means after the latter has been operated to stop the machine.

7. The combination of a machine having a bobbin with a thread thereon which is unwound during operation of said machine, a bobbin case for said bobbin, a tension device on said case for normally holding said bobbin thread under tension, an electric circuit controller responsive to a change in tension in said bobbin thread, said thread having means at a predetermined portion of its length to cooperate with said device to change said tension, and an electrically operated device connected in circuit with said circuit controller.

8. The combination with a lock-stitch sewing machine including a needle thread, a wound bobbin thread, means for maintaining said bobbin thread under tension, and means for manipulating said needle thread and said bobbin thread to form lock-stitches, of means for varying the tension on said bobbin thread at a predetermined time during operation of said machine such that upon an increase or a decrease in said tension, the amount of needle thread used in making stitches is increased or decreased respectively, and means responsive to variations in the amount of needle thread consumed.

9. The combination of a lock-stitch sewing machine including a needle thread, a wound bobbin thread having a variation in its character at a predetermined portion'of its length, means for maintaining said bobbin thread under tension, and means for manipulating said threads to form lock-stitches, said portion of said bobbin thread cooperating with said tension-maintaining means to vary the tension on said bobbin thread such that upon an increase or a decrease in said tension, the amount of needle thread used in making stitches is increased or-decreased respectively, and means responsive to variations in the amount of needle thread consumed.

10. The combination described in claim 8 with the additionofameans operable in timed relation to the speed :of said sewing machine for regulating the efiect on said responsive means of said variations in consumption of the needle thread so that the operation of said responsive means will be uniform regardless of changes in speed of operation of said machine.

11. The combination set forth in claim 8 with the addition of a signal controlled by said responsive means so that said signal will be oper ated at said predetermined time in the operation of said machine.

12. The combination Of a machine having a wound bobbin thread which is unwound by and during operation of said machine, an electric circuit controller to be actuated at a predetermined time during operation of said machine, said thread having means at a predetermined portion of it length for initiating actuation of said circuit controller, manually actuated means for controlling starting and stopping of said machine, a starting control lever which when in one position prevents movement of said manually actuated means to start the machine, a lock normally to hold said control lever in another position to release said manuall actuated means, electromagnetic means for actuating said lock to 1 a release said control lever, and means connecting said circuit controller in circuit with said electromagnetic means for actuating the latter when said circuit controller is actuated by said portion of said thread.

13. The combination of a machine having a wound bobbin thread which is unwound during operation of said machine, and a mechanism to be actuated at a predetermined time during the operation of said machine, said bobbin thread having means for controlling actuation of said mechanism, manually actuated means for controlling starting and stopping Of said machine, a starting control lever which when in one position prevents movement of said manually actuated means to start the machine, a lock normally to hold said control lever in another position to release said manually actuated means, means for actuating said lock to release said control lever, and means cooperating with said mechanism to actuate said lock-releasing means when said mechanism is actuated by said means on thread.

14. For use with means to indicate approaching exhaustion of the bobbin thread in a lockstitch sewing machine having a wound bobbin thread which is unwound by and during operation of said machine, a bobbin case having a thread tension spring which is movably mounted, and a wound bobbin thread having means at a predetermined portion of its length for momentarily moving said tension spring as said thread is unwound.

15. The combination with a wound bobbin thread having an abnormal portion, of a bobbin case having a movable part on the exterior thereof to be engaged by said abnormal portion of the thread, a device to be actuated, and an operative connection between said device and said part for actuating said device upon movement of said part.

16. For use with means for controlling the actuation of a device by an abnormal portion of the bobbin thread in a machine wherein said bobbinthread is consumed during the operation of the machine, a bobbin case having a thread outlet opening, and a part movably mounted on the exterior of the case in relation to said opening such that said part normally is stationary during withdrawal of normal thread, but will be moved when engaged by said abnormal portion of said thread.

17. The combination of a machine having a wound bobbin thread which is unwound during operation of said machine, a device normally in one position, said bobbin thread having means for actuating said device into another position upon approaching exhaustion of said thread, a signal controlled by said device and operated when the latter is in its second position, means for controlling starting and stopping of said machine, and mechanism cooperating with said device when the latter is in said second position for preventing operation of said starting and stopping means after the latter has been operated to stop the machine while said device is in its said second position, said signal indicating that the supply of bobbin thread is insuflioient and said mechanism preventing starting of the machine with an insufiicient supply of bobbin thread.

18. The combination with a lockstitch sewing machine having stitch-forming devices including a needle and a loop taker, of a wound locking thread supply about which said loop taker passes each loop of needle thread and which is 17 unwound and interlocked at a certain point with the needle thread during operation of said machine, said locking thread having an abnormal portion at apredetermined point in its length, and means including a part between saidwound thread supply and said point of interlocking of said locking thread and the needle thread directly engaged by said abnormal portion of said locking'thread during unwinding of said thread for performing an operation in timed relation to said engagement of said part with said portion of said thread.

19. The combination as defined in claim 18, wherein said abnormal portion comprises a pro.- tuberance on said thread and said part is disposed adjacent the path of movement of said protuberance from said supply to said interlocking point and is constructed to permit its momentary actuation out of said path by said abnormal portion without interruption in the unwinding of said locking thread.

20. The combination of a machine having a wound bobbin thread which is unwound during. operation of said machine, a mechanism to be actuated at a predetermined time during the operation of said machine including a part adjacent to the path of movement of said thread as the latter is unwound, said bobbin thread having means to engage said part for controlling actuation of said mechanism, and means manually predetermined portion of its length, and means 3 actuated for controlling starting and stopping of said machine, and said mechanism including including a plurality of elements at least one of P which is directly engaged by said varied portion of said locking thread between said wound supply and said point of interlocking during unwinding of said thread for performing an operation.

LEO ROSEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 875,609 Parkes Dec. 31, 1907 1,210,955 Langheck Jan. 2, 1917 1,569,074 Collins et a1. Jan. 12, 1926 2,200,720 Morin et a1. May 14, 1940 3 3 H "aw-Wm June 6, 19 4

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