US2400529A - Automatic stop device for sewing machines - Google Patents

Description

y 1946. w. A. BEHRENS 2,400,529

AUTOMATIC STOP DEVICE FOR SEWING MACHINES Filed 001;. 28, 1944 2 Sheets-Sheet 1 IN VEN TOR.

Walk/*1 Brirrnrs I May 1945- w. A. BEHRENS 2,400,529 7 AUTOMATIC STOP DEVICE FOR SEWING MACHINES I Filed Oct. 28, 1944 2 Sheets-Sheet 2 Waiferfl. Be/rrms Patented M 6 f UNITED STATES PATENT OFFICE Walter A. Behrens, Jamaica, N. 2., nssignor m Pnthe Tool Manufacturing Co. Inc., Long Island City, N. Y., a corporation of New York Application October 28, 1944, Serial No. 560,861

7 Claims. (Cl. 1l2219) use with sewing machines employing a consider-' able number of needles in'which the automatic stopping of the motor, upon failure of any one of the numerous threads, is of special importance due to the difliculty of immediately detecting such a failure. I

The present, invention permits to overcome the shortcomings of the devices of the prior art and is specifically directed to the provision of novel means controlled by the tensioning of the threads in a predetermined phase of the stitching cycle and operative to stop the motor of the sewing machine whenever any one of the threads fails to be tensioned due to the breaking thereof or other causes. One object of the invention is to provide means of the aforementioned character adapted to be most advantageously employed in multineedle sewing machines and embodying thread.

controlled contact units that are simpl and inexpensive to manufacture and small and compact in construction, so as to be easily arranged to form rows of closely spaced units adapted for association with a number of needle threads fed through the machine in close proximity to each other.

Another object of the invention is to provide a thread-controlled automatic stop device, as aforementioned, comprising contact units dependable in operation, which are concealed within a supporting structure and are protected against dust so as to substantially eliminate an possibility of failure of the device.

Since in multi-needle sewing machines, use of all the needles is' not always required, it is a further object of the invention to provide threadcontrolled contact units of the character described that may be selectively and rapidly rendered inoperative, by merely rotating the same through a fixed angle to an position.

These and other objects will become apparent in the following description of the invention illustrated in the drawings, wherein:

Fig. 1 is an end elevational view or associated elements, including a bottom bar assembly," of

a, sewing machine embodying an automatic stop ions-elements forming the bottom bar assembly.

Fig. 3 is an enlarged front'elevational view of a portion of the bottom bar assembly comprising a pair of contact units according to the invention, one oi which has been rendered inoperative.

Fig. '4 is a vertical section on line fl-d of Fig. 3, in the direction of the arrows, illustrating the position of an operative contact unit" when the thread associated therewith is tensioned.

Fig. 5 isa similar vertical section illustrating the position of the contact unit when its thread is not tensioned.

Fig. 6 is a vertical section, on line d6 of Fig. 3, through an inoperative contact unit.

Fig. '1 is a diagrammatical illustration of the ported stationary bar I I, an insulating member or block l2, a. contact element or strip l3 anda plurality of contact units. through which the threads pass. Said structure is located underneath an oscillating take-up" bar It and a fixed bar I] provided with the usual tension devices l8 for insuring uniform feed of the threads, and will fixed bar I1, is then led downwardly and through one of the contact units H of the bottom bar assembly, thence upwardly to one of eyelets 2| of the take-up bar Ii and finally downwardly again to a sewing needle 22. As will be apparent, the oscillating take-up bar IE will therefore, once .during the stitching cycle, tension all the threads in use in the machine and cause the threads to exert an upward pull on the respective contact units ll through which they pass, for the purpose and with the results to be later described.

With the exception of the bottom bar assembly II, which will be hereafter described more in detail, the aforementioned elements are conventional and only so much of the structure thereof has been shown in the drawings as is required to illustrate the relation thereto of the bottom bar assembly I and to permit a complete understanding of the invention. The stationary bar II is grooved to provide therein a plurality of recesses 23 uniformly spaced cally and rotatably movable therein. Each of the contact units consists of a body formed of a porcelain eyelet 2G and-a pair ofbrass eyelets or grommets 21, 28, assembled on the porcelain eyelet and having flanges that extend in juxtapositake-up bar I6 is operated to tension the threads I I. At that moment, therefore, all the contactunits I4 are displaced upwardly to-the position of Fig. 4, and consequently no current will flow to the relay 45 notwithstanding the closing of the switch 44, so that the operation of th motorwill tion to opposed faces of the bar II to prevent tioned insulating block I2, of Bakelite" or like material, which is offset relative to the bar to. provide a projecting portion orled'ge underneath the flanges of the grommets 23. The contact strip not be interrupted.

Should, however, any of the threads be broken,

or for any other reason not under tension at the instantof the take-up, the respective contact unit I4 will retain its strip-contacting position under the influence of its spring'25, and will bridge the.

circuit thereby permitting ,flow'of current to the relay 45 andcausing the solenoid 43 to be energized to open the motor circuit switches 42 and immediately shut off the motor.

- Since in a multi-needle sewing machine certain of the needles may sometimes not be in use, and

or element I3, preferably made of brass, is secured to the block I2, as by means -of screws 34, opposite the projecting portion of the block, and is provided with spaced projections or bosses 36 alined with the contact units I4, inwardly of the flanges of -the.grommets 21.

The contact units I4 are normally disposed in I maintain the grommet 21 thereof in surface en-' gagement with the respective boss 38 of the con.- tact strip I3 alined therewith, as shown in Fig. 4, provided the thread I9 passing through the porcelain eyelet 26 of the unitis slack. Upon tensioningof the thread, following the operation of the take-up bar once during each stitching cycle, as aforementioned, the unit I4 will be pulled upwardly away from the associated boss 36 of the contact strip I3, to the position illustrated in Fig. 4. Failure of any one of the threads to displace the respective unit I4 at the instant of the takeup, will result in stopping the motor which drives the machine, in the manner that will now be-de; scribed. 1

As illustrated in Fig. 7, the power circuit of the electric motor of the sewing machine comprises normally clos d switches 42, which may be the contact units associated therewith would then not be controlled by the threads, it is apparent from the foregoing that such contact units must be rendered inoperative to prevent the same from stopping the machine in synchronism with the operation of the take-up bar.

For this purpose, it is suflicient to rotate an desired contact units through an angle of 90 degrees,-to dispose the edge 3| of the flange of the grommet 28 thereof parallel to the upper face of the projecting portion of the insulating block I2. In such a position of the flange, the unit is prevented from moving into contact with the respective boss of the contact strip I3 by the abutment of the edge 3! 'on the insulating block I2, as shown in Fig. 6, and is therefore ineffective to bridge the circuit described at any time. Manifestly, the unit may readily be returned to its operative position through aninverse directional movement thereof. I i

It 'is to be understood that numerous changes and modifications may be made in the structure described and illustrated in the drawings without departing from the spirit of the invention or exceeding thescope of the claims;

I claim: 1 In a motor driven multi-needle sewing machine having means for' tensioning the threads in a predetermined phase of'eachstitching cycle,

opened to shut off ,he'motor by a solenoid 43. Q

' This latter forms part of an open electric circuit,

suitablyconnected to the motor power circuit,

4 which also includes a switch and a vacuum tube relay 45 for energizing the solenoid 43, and 3 which is bridged by the contact strip l3 and con.- tact-units I4 when these latter are in the stripcontacting position-shown in Fig. 5. Normally,

during operation of the machine, the threads are A shaft 46 driven from the motor 4|! through suitable speed-reducing transmission, carries a cam 41 acting to close the switch 44 once during each stitching cycle at the instant in which the a normaly open electric circuit, means actuated upon closing'of said circuit for stopping the motor, and means for controlling the closing of said circuit, said last mentioned means comprising a normally open switch periodically closed in synchronism with the tensioning of the threads and a plurality of contact units each associated with bridging position simultaneously with the closing having means for tensioning the threads in a,

predetermined phase of each stitching cycle, a normally open electric circuit, a contact element connected in said circuit, a plurality of contact units each associated with one of the threads,

said units being normally held in contact with said contact element to bridge said .circuit and being displaceable by the tensioning of the threads from said normal position thereof, means effective upon closing of the circuit to stop the motor. means for closing the circuit in synchronism with the tensioning of the threads, the tensioning of the threads simultaneously causing the contact units to be displaced by the threads fromsaid normal position thereof thereby normally preventing the actuation of the means for stopping the motor, the failure of any ne of the threads to be tensioned causing the respective contact unit to maintain its normal circuit bridging position thereby permitting operation of the means for stopping the motor.

3. In a motor driven multi-needle sewing machine having means for tensionlng the threads in a predetermined phase of each stitching cycle, a stationary bar, an insulating block and a contact element carried by said bar, a plurality of contact units movably mounted in said bar, each comprising a body through which one of the threads passes and a pair of metal eyelets mounted on said body one of which is maintained in contact with said contact element in the normal position of the unit, said units being displaceable by the tensioning of the threads from said normal position thereof, means effective at'the instant of the tensioning of the threads to stop the motor whenever any one of said contact units main- I tains its normal position due to the failure of the respective thread to displace the same, each of said units being rotatable in said stationary bar and one of said metal eyelets of the unit having a flange adaptcd'to engage in the rotation of the unit said aforementioned insulating block to lock the unit in a position wherein the aforementioned contact eyelet is prevented from contacting said contact element, whereby any one of the units may be selectively rendered inoperative.

i. In a motor driven multi-needle sewing machine comprising means for tensioning the threads in a predetermined phase of each stitching cycle, a normally open electric circuit including a switch periodically closed in synchronism with the tensioning of the threads and means for stopping the motor upon closing of said cir cult, a device for controlling the closing of said circuit comprising a stationary supporting memher, a fixed contact element associated with said member and connected in the circuit, a plurality of contact units movably mounted in the supporting member, and means'for normally maintainin said units in contact with said fixed contact element to bridge the circuit, each of said units being associated with one of the threads and adapted to be displaced by the tensioning of the respective thread from its normal position, the failure of any one of the threads to be tensioned causing the associated contact unit to maintain its normal position thereby determining the closing of the circuit.

5. In a motor driven multi-needle sewing machine comprising means for tensioning the.

threads in a predetermined phase of each stitching cycle, a normally open electric circuit including a switch periodically closed in synchronism with the tensioning of the threads and means for stopping the motor uponclosing of said circuit, a device for controlling the closing of said I circuit comprising a stationary supporting member, aflxed contact element associated with said member and connected in the circuit, a plurality of contact units movably mounted in the supporting member, and means for normally maintaining said units in contact with said fixed contact element to bridge the circuit, each of said units being associated with one of the threads and adapted to be displaced by the tensioning of the respective thread'from its normal position, the failure of any one of the threads to be tensioned causing the associated contact unit to maintain its normal position thereby determinin the closing of the circuit, said contact units being rotatable in the supporting member to a position in which contact thereof with the fixed contact element is prevented 'at all times whereby any one of the units may be rendered selectively inoperative. I

6. In a motor driven multi-needle sewing machine comprising means for tensioning the threads in a predetermined phase of each stitching cycle, a normally open electric circuit includfor normally maintaining said units in circuitbridging position, each of said units being displaceable by thetensioning of the respective thread from its normal position and the failure or any one of the threads to be tensioned causing the associated contact unit to maintain its normal position thereby determining the closing of the circuit,

7. In a motor driven multi-needie sewing machine comprising take-up means for tensioning the threads in a predetermined phase of each stitching cycle, a normally open electric circuit including a switch'periodically closed in synchronism with the tensioning oi the threads and means for stopping the motor upon closing of said circuit, a device for controlling the closing of said circuit comprising a stationary support, an insulating block and a contact element connected in said circuit carried by said support, a plurality of contact units movably mounted in said support, each comprising a body through which one of the threads passes and a member carried by said body adapted to contact said contact element to bridge the circuit, and resilient means mounted in the support for normally maintaining said units in circuit-bridging position, each of the units being displaceable bythe tensioning of the respective thread from its normal position and the failure of any one of the threads to be tensioned causing the associated contact unit to maintain its normal position thereby determining the closing of the circuit, each unit being rotatable in the support to a position in which contact of the member carried by the body of the unit with the contact element aforementioned is prevented at all times, whereby any one of the units may be rendered selectively inoperative. v I WALTER A. BEHRENS.

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