US3455259A

US3455259A - Automatic motion stoppage mechanism for zigzag sewing machines

Info

Publication number: US3455259A
Application number: US711001A
Authority: US
Inventors: Herbert Wenz; Fritz Jehle
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1967-03-09
Filing date: 1968-03-06
Publication date: 1969-07-15
Anticipated expiration: 1986-07-15
Also published as: DE1660966B1; GB1160203A

Description

7 July 15, 1969 @H.WENZ ETAL Filed March 6, 1968 F ig. 1

3 Sheets-Sheet 1 INVENTORS HERBERT WENZAK FR/FZ 7504! H4 H4. RAT/I July 15, 1969 .H. WENZ Er 3,455,259

AUTOMATIC om STOPPAGE MECHANISM FOR zmzmsnwme MACHINES- Filed March 6, 1968 3 Sheets-Sheet 2 JNVENTOR) HEERERT WE/VZ .2 BY Fe/r Z VEHLE mea R47 ATIONEY July 15, 1969 H. WENZ ETAL 3,455,259

AUTOMATIC MOTION STOPPAGE MECHANISM FOR ZIGZAG SEWING MACHINES Filed March 6, 1968 Y 3 Sheets-Sheet 5 Fig. 3

INVENTORS 1 5 51 wewz .8 BY g/rz 75 14:

144 RAT/l ITI'GR VEY United States Patent 3,455,259 AUTOMATIC MOTION STOPPAGE MECHANISM FOR ZIGZAG SEWING MACHINES Herbert Wenz, Kaiserslautern, Pfalz, and Fritz .Iehle, Alsenborn, Pfalz, Germany, assignors to G. M. Pfalf AG, Kaiserslautern, Pfalz, Germany, a corporation of Germany Filed Mar. 6, 1968, Ser. No. 711,001 Claims priority, application Germany, Mar. 9, 1967, P 41,594 Int. Cl. D05b 3/02, 69/22 US. Cl. 112219 Claims ABSTRACT OF THE DISCLOSURE In a conventional zigzag sewing machine equipped with automatic motion stoppage means, to arrest the machine in either the DOWN or UP position of the needle, means are provided consisting essentially of a periodic control switch operated in synchronism with the needle zigzagging oscillations, to disable the automatic stoppage means during the lateral needle excursions in a predetermined direction from the center needle stitching position, thereby to restrict arresting of the machine to intervals during the needle excursions in the direction opposite to said predetermined direction. Where a conventional slip ring type synchronizing switch is used having a cooperating brush and provided with an insulating segment, to control the needle position at the instant of arresting the sewing machine, the periodic control switch by-passing said synchronizing switch and determining the right or left stitching position at which the stoppage occurs, may be actuated by the oscillating bar actuating the needle bar supporting frame effecting the needle zigzagging excursions, or an auxiliary slip ring synchronizing switch may be provided as a control switch being driven at half the speed of the main synchronizing switch, both said synchronizing switches having insulating segments arranged to engage their respective brushes at desired predetermined either UP and DOWN and either RIGHT and LEFT needle stitching positions, respectively.

The present invention relates to zigzag sewing machines, more particularly to machines equipped with automatic motion stoppage means, to arrest a machine at a predetermined needle position, such as the DOWN or workengaging and UP or work-disengaged position of the needle within its reciprocating vertical operating path.

It is already known, for the foregoing purpose, to equip zigzag sewing machines with a relatively slow-running auxiliary drive in addition to its main relatively fast-running drive operably connecting the driving motor with the input drive or arm shaft of a machine and effective during the carrying out of a sewing operation proper. The main drive may be effected, in accordance with conventional practice, via a friction driving disk, while the connection and disconnection of the auxiliary drive is advantageously effected by the aid of an electromagnetic clutch and brake in cooperation with associated electrical switching means. In the conventional stoppage arrangements, the dis-connection of the auxiliary drive, to effect the final stoppage of the machine, is controlled by a timing contactor or synchronizing switch being advantageously in the form of a slip ring and cooperating contact brush and driven by the main drive shaft of the sewing machine, said slip ring being provided with an insulating segment, to interrupt the electrical circuit and to simultaneously energize the brake of the auxiliary drive, to stop the sewing machine in the desired needle position determined by the relative position of said segment and said contact brush.

The automatic motion stoppage mechanism may comice prise a plurality of slip rings or synchronizers selectively connectible in the control circuit of the auxiliary drive, to enable a stoppage of the machine at different predetermined and selectable needle positions, in particular the DOWN and UP position, or raised position of the thread take-up lever, respectively.

Principally, the operation of the known motion stoppage devices involves the braking or deceleration of the machine, prior to the initiation of the stoppage proper, to a considerably reduced rotating speed by the connection of the auxiliary drive and simultaneous disconnection of the main drive of the machine, to ensure a safe and instant stopping at the desired needle position, that is, upon the insulating segment of the slip ring engaging its cooperating brush contact, to interrupt the control circuit and to simultaneously energize the brake of the auxiliary drive.

The stoppage of the sewing machine at a predetermined needle position is required, for instance, where the work is to be rotated, to change the sewing direction, with the needle in the DOWN or work-engaging position, or where the threads are to be cut at the end of a sewing operation, or finally where the work is to be removed and a new workpiece to be inserted in the UP or workdisengaged position of the needle. Inasmuch as both the needle and looptaker threads assume their most favorable position, that is for the seizure by the thread catching and operation of the cutting devices, during the upward movement of the needle from its DOWN or work-engaging position, it is customary to effect the stoppage of most of the sewing machines, prior to the initiation of the thread cutting operation, in the DOWN position of the needle, such as by connection of the auxiliary drive and operation of the thread cutting mechanism. In the latter case, the threads are seized during the first half revolution of the armshaft and cut by operation towards a stationary cutting knife. Subsequently, the sewing machine is automatically arrested in the UP position of the needle by the action of the synchronizer or stoppage device referred to hereinabove.

In the case of zigzag sewing machines equipped with motion stoppage mechanism of the foregoing type, it is normally left to chance in which of the two right and left needle stitching positions the stoppage is effected at the end of a sewn zigzag seam. This has made it impossible in the past, among other drawbacks and shortcomings, especially in the case of zigzag sewing machines equipped with thread-cutting means and operated to produce Zig zag overstitches about the edge of the workpiece by the needle engaging the work in one of the lateral stitching positions and moving past or being disengaged from the edge of the work in its opposite lateral stitching positions, to ensure in advance that the machine is in a position suitable for the cutting of the threads with a minimum of the projecting thread ends, that is, the position of the needle entering or engaging the work in the DOWN position. If, on the other hand, the machine is arrested in the position of the needle being outside of or disengaged from the edge of the work, it will be necessary, prior to the operation of the thread cutting device, to re-start the sewing machine and to produce one more stitch, thereby involving unnecessary delays as well as other drawbacks. The prior arrangements have made it furthermore impossible to comply with the requirement of storing a command pulse simultaneously with the initiation of a stopping operation, to effect a delayed operation of the thread cutting device upon completion of the stopping operation. It was rather necessary, for the latter purpose, to wait with the operation of the thread cutter until the machine has assumed a position most favorable for the cutting operation, involving thereby additional delays and drawbacks readily understood.

Accordingly, an important object of the present invention is the provision of improved automatic motion stoppage mechanism of the referred to type especially adapted for zigzag sewing machines, by which the foregoing and related drawbacks and difiiculties are substantially overcome.

Another object of the invention is the provision of automatic motion stoppage means to arrest a zigzag sewing machine in any desired position of its composite needle operating path resulting from both the reciproeating or up and down needle movements and the lateral excursions of the needle from its center stitching position for the production of zigzag stitches in the work operated on.

A more specific object of the invention is the provision of automatic work stoppage mechanism for zigzag sewing machines enabling a selective stopping of the machine in either of the right or left stitching positions of the needle from its center stitching position, on the one hand, and with the needle in either the DOWN or UP position, respectively.

The invention, both as to the foregoing and ancillary objects as well as novel aspects thereof, will be better understood from the following detailed description of a preferred practical embodiment, taken in conjunction with the accompanying drawings forming part of this specification and in which:

FIG. 1 is a composite schematic elevational view, shown partly in section, and wiring diagram for a zigzag sewing machine embodying automatic motion stoppage mechanism constructed in accordance with the principles of the invention;

FIG. 2 is a View similar to and showing a modification of FIG. 1; and

FIG. 3 is a partial diagram illustrating one of the special aspects and uses of the invention.

Like reference numerals denote like parts in both views of the drawings.

With the foregoing objects in view, the invention, according to one of its aspects for the stoppage of a zigzag sewing machine in the DOWN and either of the RIGHT or LEFT lateral stitching positions of the needle, involves generally the provision of a periodic control switch operated in synchronism with the needle zigzagging oscillations, said switch being arranged and connected with the main synchronizing switch controlling the UP and DOWN stopping position of the needle, whereby to by-pass and disable said synchronizing switch during the non-desired lateral excursions of the needle in one direction from its central stitching position, or to restrict the stoppage of the machine to the intervals during the lateral excursions of the needle in the desired or opposite directions from said central stitching position. Advantageously, the control switch is in the form of a two-pole switch connected to the synchronizing switch through a selector switch, the latter serving to control in advance the stoppage position of the machine in a desired RIGHT or LEFT needle stitching position.

By the provision of two or more synchronizing switches, such as in the form of a pair of slip rings having differently positioned insulating segments, and a further changeover switch connected therewith, proper connection of the latter, to insert either of the synchronizing switches in the control circuit of the auxiliary drive, will enable it to selectively stop the machine with the needle in one of the vertical (UP and DOWN) and either of its lateral (RIGHT and LEFT) positions or excursions, in a manner as will become more apparent from the description in reference to the drawings.

The invention, aside from the considerable saving of time and as a result of the selective stopping of the machine in either of its lateral stitching positions, makes it furthermore possible to utilize the improved stoppage mechanism, to stop a zigzag sewing machine at the end of a seam at a desired lateral needle stitching position,

in conjunction with machines of the type which operate with an extremely large overstitch Width and where the thread-cutting device is disposed, due to space limitations, below the cloth plate of the machine, in an effort to reduce the operating stroke and, in turn, the projecting length of the cut threads, to a practical minimum.

According to an especially simplified construction and in order to ensure a safe operation of the stoppage mechanism without re-adjustment of the control switch, for the sewing of seams of varying overstitch width Within the full operating range of the machine, the periodic control switch is advantageously of the type comprising a proximity-controlled vibrating reed cooperating with a pair of stationary contacts and actuated by a permanent magnet mounted upon the reciprocating actuating bar or link of the needle bar supporting frame, said reed being mounted in an inert atmosphere and disposed in proper position to said magnet, in a manner described in greater detail hereafter.

Alternatively, the periodic control switch determining the lateral needle position at which the stoppage of the machine occurs, may be in the form of an auxiliary slip ring synchronizer, similar to the main slip ring synchronizer, determining the needle UP or DOWN stoppage position of the machine, said auxiliary synchronizer rotating at a speed equal to one half of the speed of said main synchronizer and having an insulating segment positioned and related to the insulating segment of the main synchronizer, in such a manner as to enable an interruption of the control circuit of the auxiliary drive and stoppage of the sewing machine during a single one only of the needle zigzagging excursions from the center needle stitching position, as will become further apparent from the following detailed description in reference to the drawings.

Referring more particularly to FIG. 1, there is shown a conventional zigzag sewing machine having a cloth plate 1 which supports a casing 2 comprised in a known manner of an upright and overhanging arm, the latter having mounted therein the main drive or armshaft 3 of the machine. The latter carries, at its end projecting from the casing 2, the needle stoppage control or synchronizing switch 7 consisting, in the example shown, of three juxtaposed slip rings of conducting material 4, 5 and 6. The slip rings 4 and 6 are provided with peripheral insulating segments or

inserts

8 and 9, respectively, being displaced by in respect to one another and serving to control the stoppage of the sewing machine in the needle DOWN and UP positions, respectively, while the slip ring 5 serves as terminal means for applying operating current to the device. While three separate slip rings 4, 5 and 6 are shown in the drawing, a single integral annular member of adequate width may be provided fitted with properly axially and angularly spaced

insulating segments

8 and 9 and cooperating with three properly arranged contact brushes or springs B, in the manner shown and readily understood.

Secured to the opposite end of the shaft 3, within the housing 2, is a crank 10 having a crank pin 11 which in turn supports a needle bar driving arm 12. The latter is operably connected, via a needle bar pin or coupling 15 of the needle bar 14 slidably supported in the needle bar frame 13, needle bar 14 carrying the needle 16, in the manner shown and understood by those skilled in the art.

By the provision of mechanism described in the foregoing, rotation of the armshaft 3 by the driving motor of the sewing machine, as described hereafter, causes a reciprocating up and down movement of the needle bar 14 and, in turn, of the needle 16, to result in a stitch formation in the work operated on in cooperation with a conventional hook or looptaker (not shown).

The needle bar frame 13, being secured to one end of an oscillating or shift bar 17, is mounted in a guide 18 fast upon the casing 2, to prevent rotation of said frame about a vertical axis and to impart oscillating motion to the needle at right angle to the sewing direction in addition to the vertically reciprocating needle movements, for the formation of zigzag stitches in a manner Well known. The opposite end of the oscillating or shift bar 17 is linked, by means of a pivot pin 20, to one end of an eccentric rod 19 whose opposite and fork-shaped end cooper-ates with a triangular eccentric 21 driven by a first bevel gear 22 which meshes with a second #bevel gear 23 mounted upon the armshaft 3. The transmission ratio of gears 22, 23 is such as to cause the eccentric 21 to rotate at a speed equal to one half of the rotating speed of the shaft 3.

In order to produce zigzag stitches of a desired overstitch width by the needle 16 in the work operated on and advanced by a suitable feeding device (not shown) in the stitching direction, that is, at right angle to the needle zigzag excursions or oscillations, there is provided an overstitch controller comprising a disk 24 rotatively mounted upon the casing 2 and provided with a diagonal guide slot 25 in which is slidably mounted a guide block 26. The latter is rotatively supported by a pivot pin 27 secured to an intermediate point of the eccentric rod 19. The angular adjusting position of the disk 24 and, in turn, of the guide slot 25 may be controlled by the aid of a suitable control knob (not shown) mounted upon the casing 2, whereby to result in the variation of the overstitch width or amplitude of the zigzagging oscillations of the needle 16.

The sewing machine is continuously driven by an electric motor 28 whose rotor 29 drives the main friction coupling or driving disk 31 fast on the motor shaft 30 and forming part of the main (fast-running) drive of the sewing machine, on the one hand, said rotor furthermore driving a pulley 35 forming part of an auxiliary (slowrunning) drive of the machine, and said auxiliary drive comprising a further pulley 32 fast on the motor shaft 30, a driving belt 34 and guide rollers 33 (only one being shown in the drawing) operably connecting the pulleys 32 and 35. Pulley 35 is freely rotatively supported by a further shaft 36 of the auxiliary drive carrying a clutch or coupling disk 37 axially slidable thereon. Shaft 36 furthermore carries a Worm 38 which meshes with a worm gear 39 forming part of a braking disk 40 of the motor 28. Disk 40 is freely rotatively supported by a shaft 43 axially displaceable, against the action of a spring 41, by the aid of a starting or control lever 42. Shaft 43 carries a further coupling disk 44 which may be selectively frictionally coupled, by the actuation of the lever 42 via a foot pedal or the like, with the main driving disk 31 of the motor 28, on the one hand, and with the disk 40 of the auxiliary drive, on the other hand, in the manner and for the purpose as will become further apparent as the description proceeds.

The arm shaft 3 of the sewing machine is driven in a known manner via the hand wheel 45 and a pulley 46 fast on the shaft 43, by means of a driving belt or the like 47.

In order to connect and disconnect the auxiliary drive, the pulley 35 is fitted withan electromagnet 48, hereafter referred to as the coupling magnet, while a further electromagnet 50, hereafter referred to as the braking magnet, is mounted upon a stationary braking member or disk 49. As a consequence, energization of the coupling magnet 48 results in the attraction of the coupling disk 37 towards the pulley 35 and rotation of shaft 43 by the pulley 35 through shaft 36 and

worm gear drive

38, 39, while interruption of the circuit of the magnet 48 results in the release of the coupling disk 37 from the pulley 35 and instant braking of the shaft 36 to full stoppage by the simultaneous energization of the magnet 50, in the manner described in further detail in reference to the operation of the invention.

The connection and disconnection of the coupling and

braking magnets

48 and 50 is controlled by a relay 51 energized from a DC source and comprising a pair of

stationary contacts

52 and 53 cooperating with a movable contact arm 54. The operating current for the relay 51 and coupling and

braking magnets

48 and 50 is supplied, in the example shown, by a bridge rectifier power supply comprising four solid state or the like rectifying elements and being energized, simultaneously with the energization of the motor 28, from an AC power network via a stepdown transformer 55, in accordance with conventional usage and practice. The rectifier output terminals supplying the operating current for the relay 51 are designated by numerals 57 and 58 in the drawing. The contact arm 54 of the relay 51 is connected, via a lead 59, terminal 60 and a lead 61, with the rectifier pole or terminal 57, relay contact 53 is connected, via a lead 63, with one terminal of the coupling magnet 48, and relay contact 52 is connected, via a lead 62, with one terminal of the braking magnet 50, the remaining terminals of said coupling and braking magnets being connected, via common junction point 94 and a lead 92, with the remaining pole or terminal 58 of the rectifier 56.

In order to selectively control, in dependence upon the LEFT or RIGHT needle stitching position, the stoppage of the sewing machine in the DOWN position of the needle as shown by the drawing, that is, while the needle is engaged in the work operated on, there is provided, according to the improvement of the present invention, a two-pole control switch 64 mounted in the casing 2 and connected in the control circuit of the auxiliary drive of the machine, said control switch being effectively in parallel to the synchronizing switch 7 and serving to periodically short-circuit the latter during one of the zigzag excursions of the needle, in such a manner as to efiect a stoppage of the machine by the synchronizer 7 in the desired and selectable LEFT or RIGHT needle stitching DOWN position, in the manner as will become further apparent as the description proceeds.

In the embodiment of the invention according to FIG. 1, the control switch 64 is advantageously comprised of a vibratory reed contact 65 mounted in an evacuated vessel or space filled with an inert gaseous atmosphere and actuatable from the outside by a displaceable permanent magnet actuator 68, to close either of a pair of fixed

contacts

66 or 67 by the reed 65, in a manner well known with switching devices of this type. In the instant case, actuating magnet 68 is mounted upon the shift or oscillating bar 17 of the zigzag drive described in the foregoing, whereby to alternately close the contact pairs 65, 66 and 65, 67 during the opposite zigzag excursions of the needle 16. More particularly, in the example shown, the switch 64 is controlled by the magnet 68 in such a manner that, during the sewing of a zigzag seam and as viewed from the position of the seamstress, the contact 65 engages, by virtue of its own resiliency, the contact 66 during the needle excursions towards the right from the center stitch ing position, to effect the stoppage of the machine in the RIGHT needle position, and that the contact 65 engages or closes the contact 67 during the needle excursions towards the left from said center stitching position, whereby to effect the stoppage of the machine in the LEFT needle position.

The reed 65 is connected, via a lead 69 and lead 61, with the pole 57 of the rectifier 56, lead 61 furthermore serving to supply operating current to the slip ring 5 of the synchronizer 7. The stationary contact 66 of the switch 64 is connected, via a lead 70, with a contact 71 and the stationary contact 67 of the switch 64 is connected, via a lead 72, with a contact 73, both said

contacts

71 and 73 forming part of a two-pole selector switch having a contact arm 74 inserted in a lead 75, the latter being connected, via the slip ring 4, having insulating segment 8 for the needle stoppage in the DOWN position, and the winding of the relay 51, with the pole 58 of the rectifier 56. The selector switch 74, which serves to control the stoppage of the machine with the needle in either the RIGHT or LEFT stitching position, may be in 7 the form of a snap switch or control key provided with suitable markings Left and Right, respectively.

In the foregoing, it has been assumed that the magnet 68 is arranged in such a position relative to the switch 64 as to result in substantially equal closing times of the

contacts

66 and 67 by the reed 65 during the lateral needle excursions from the central stitching position. An advantage of the type of switch shown with the actuating magnet physically separated from the relay operating contacts is the fact that the relative closing times of the

contacts

66 and 67 may be varied for the achievement of special effects, or to comply with special operating conditions. Such a case obtains, for instance, where the motion stoppage device is to be utilized in conjunction with a thread cutter having a relatively short operating stroke in the interest of reducing the projecting ends of the threads being cut, and where the machine is to be operated over a rather wide range of over-stitch widths, or beyond the limit covered by said cutter. In such a case, a proper relative adjustment of the magnet 68 and switch 64 will enable a safe cutting of the threads substantially independently of the overstitch Width, as will become further apparent from the following in reference to FIG. 3.

Referring to the latter, let it be assumed that the thread catcher F of a conventional thread cutting device has an operating stroke, as indicated by the solid and dot-dashed lines, that is being slightly greater, say by 1 mm., than one half of the maximum overstitch width W of say 10 mm. Under this condition, stoppage of the sewing machine in the manner described and thread cutting within either of the needle excursions is limited to the relatively small overstitch width S of 2 mm. in the example illustrated. However, by the proper relative adjustment of magnet 68 and switch 64, the stoppage device may be adapted to the limited operating stroke of the thread cutter, to enable a safe cutting of the threads after the sewing of seams of any overstitch width within the range of the machine.

More particularly, in the case of the foregoing example, that is, for a minimum overstitch width 5 of 2 mm. and a maximum overstitch width of mm., the magnet 68, mounted upon the shift bar 17, is so positioned relative to the switch 64 as to cause the

contacts

65, 67 to be opened over the limited outer range R (4 mm. according to the example) during the needle excursions towards the right, and to cause the

contacts

65, 66 to be opened over the remaining range L (6 mm. according to the example) of the needle excursions, respectively. As a consequence, the sewing machine, upon return of the starting lever 42 to its rest position, will be stopped in the needle DOWN position, with switch 76 in the position shown in FIG. 1, after sewing of a narrow zigzag seam of 1 mm. width in either of its RIGHT or LEFT needle positions, depending upon the position of the switch 74, whereas, upon the sewing of a seam of greater overstitch width W, the machine can be stopped only in the LEFT needle position, forming the starting point for the thread catching and cutting operations, that is, with the contact arm 74 engaging the contact 71 as shown in FIG. 3. As a consequence, the thread cutter may have a limited operafing stroke, to result in short projecting ends of the threads being cut.

Further inserted in the lead 75 are the contacts 77 of a changeover switch 76 which, besides the contacts 77, has a further contact pair 78 one of which is connected, via a lead 79 and terminal 80, with the lead 75 and the other contact of which is connected to a lead 81 which is in turn connected with the slip ring 6 having an insulating segment 9 for the stoppage of the needle in the UP position. The changeover switch 76 serves to selectively connect the relay 51 with the slip rings 4 and 6, to control the stoppage of the sewing machine with the needle in either the DOWN or UP position, respectively. Besides, the switch 76 enables the carrying out of a siitch-by-stitch 8 sewing by alternately closing and opening the

contacts

77 and 78.

According to the embodiment of FIG. 2, the switch to control the needle stitching position in which the stoppage of the sewing machine is affected, in either the DOWN or UP position of the needle, is replaced by an auxiliary synchronizing switch 82 similar to the main synchronizer 7 and consisting, in the example shown, of three

slip rings

83, 84 and 85 mounted upon a shaft 86 rotatively supported in the casing 2 and driven, via a bevel gear pair 87, 88, by the drive shaft 3, in such a manner as to rotate the

rings

83, 84 and 85 at half the rotating speed of said shaft. The

rings

83 and 85 are fitted with insulating segments 89 and 90, respectively, the latter being relatively displaced by 180 and coordinated with the left and right needle stitching positions, in the manner further described in and understood from the followmg.

Slip ring 83 is connected, via a lead 72, to contact 73 of the selector switch 74-, slip ring 84 is connected, via leads 91 and 61 to the pole 57 of the rectifier 56, while the slip ring 85 is connected, via a lead 70, to the contact 71 of the switch 7 4.

The operation of the invention as shown by FIG. I is described in the following.

Let it be assumed, as represented by the position shown by FIG. 1, that the sewing machine is adjusted, by the setting of the overstitch controller 24, for the sewing of a zigzag seam of desired overstitch width and, furthermore, that the machine has been arrested with the needle in the DOWN (work engaging) and RIGHT zigzag stitching position, as viewed from the position of the seamstress, that is, in the direction towards the plane of the drawing. In this position, the main driving disk 31 of the motor 28 is disengaged from the coupling disk 44, as is the driving connection of the auxiliary pulley drive 32, 33, 34 between the continuously running motor shaft 30 and the auxiliary pulley 35 or clutch disk 37, respectively. As a consequence, the coupling disk 44 engages the braking disk 40, the arm 54 of relay 51 is in the released position and the braking magnet is energized via lead 61, connected to the pole 57 of the rectifier 56, lead 59, contact arm 54, contact 52, lead 62, the winding of the magnet 50, lead 93, terminal 94, lead 92 to pole 58 of the rectifier 56. As a consequence, the coupling disk 37 is urged into engagement with the stationary braking disk 49. Furthermore, in this position the brush B of the slip ring 4 engages the insulating segment 8, the contacts and 67 of the control switch 64 are disengaged or in open position, the contact arm of switch 74 engages the contact 73, and the contacts 77 of the changeover switch 76 are in the closed position, all as shown in FIG. 1.

In order to operate the sewing machine in the position of FIG. 1, after completion of a sewing operation, from the needle DOWN position to the needle UP position, for the removal of the work and insertion of a new workpiece, the changeover switch 76 is operated manually from the position shown to its position of closing the contacts 78, whereby to establish a current flow from the pole 57 of the rectifier 56 through lead 61, slip rings 5 and 6, lead 81, contacts 78, leads 79 and 75, relay 51 and back to the pole 58 of the rectifier 56. As a consequence, relay 51 is energized, whereby switch arm 54 engages contact 53, thus energizing the coupling magnet 48 by a circuit traced from pole 57 of rectifier 56 through lead 61, terminal 60, lead 59, contact arm 54, contact 53, lead 63, the winding of magnet 48, terminal 94 and lead 92 and back to pole 58 of the rectifier 56. As a consequence, the clutch disk 37 is attracted towards and coupled with the relatively slower running pulley 35, whereby the sewing machine is operated, at reduced speed, to the needle UP position via the spring 36,

worm gear drive

38, 39, braking disk 40, coupling disk 44, shaft 43, pulley 46, belt 47,

and hand wheel 45. As soon as the brush B of the slip ring 6 reaches its position opposite the insulating segment 9, corresponding to the needle UP position, the relay 51 is again deenergized, whereby to cause the contact arm 54 to re-engage the contact 52 and to reenergize the braking magnet 50. The resultant current flow is traced from the pole 57 of the rectifier 56 through lead 61, terminal 60, lead 59, contact arm 54, contact 52, lead 62 and leads 93 and 92 to the pole 58 of the rectifier 56. Due to energization of the braking magnet 50, the clutch disk 37 being fast on shaft 36 is eifectively braked or decelerated, thus ensuring a safe and instant stoppage of the sewing machine in the desired UP position.

After removal of the workpiece in the needle UP position of the machine and insertion of a new workpiece, for the sewing of another zigzag seam, the coupling disk 44 is engaged, by the operation, against the action of spring 41, of the starting lever 42 by the aid of a foot pedal or the like (not shown), with the main driving disk 31 mounted upon the shaft 30 of the motor 28, whereby to start operation of the sewing machine at normal operating or sewing speed by way of pulley 46 mounted upon shaft 43, belt 47 and hand wheel 45. As a consequence, there is imparted, via crank 10, link 12 and needle bar coupling 15, vertical reciprocating movement to the needle bar 14 and needle 16, simultaneously with the application, by way of the bevel gear pair 22, 23, eccentric 21, eccentric rod 19, guided by the block 26 in the slot 25, of to and fro or oscillating movements to the needle bar frame 13 at right angle to the feed direction. Inasmuch as the eccentric 21 completes a single revolution during two revolutions of the drive shaft 3, the needle 16 enters the workpice alternately at its left and right oscillating positions, whereby to produce zigzag stitches in the work operated on in cooperation with a suitable looptaker (not shown), in accordance with standard zigzag sewing machine operation.

The effect of the permanent magnet 68 mounted upon the oscillating bar 17 is to close the

contacts

65 and 67 during the left excursion of the needle, that is, within the region between the Center and Left stitching positions, on the one hand, and to close the

contacts

65 and 66 during the right excursions of the needle, that is, within the region between the Center and Right needle stitching positions, on the other hand. This operation has normally no effect on the relay 51 which has been energized at the starting of the sewing machine, whereby to energize the coupling magnet 48, via contact arm 54, contact 53 and lead 63, as soon as, with the contacts 78 of the changeover switch in the closed position, the brushes B of the slip ring 4 become disengaged from the insulating segment 8. As a consequence, the shaft 36 and braking disk 40 are driven, via clutch disk 37 and the

worm gear pair

38, 39, at a considerably reduced speed compared with the rotating speed of the motor shaft 30.

If the switches 74 and 76 are in the position as shown in FIG. 1, that is, for the stoppage of the sewing machine in the needle DOWN and RIGHT stitching positions, the current through relay 51 is briefly intermittently interrupted, during the normal operation of the sewing machine, by the engagement of the brush B of the slip 4 with the insulating segment 8, while at the same time the

contacts

65 and 67 of the control switch 64 are disengaged from one another. The relay 51 remains, however, energized on account of its magnetic inertia as long as the coupling disk 44 is engaged with the main driving disk 31 of the motor 28 and the machine rotates at normal and relatively high operating speed.

After completion of the zigzag sewing operation, the coupling disk 44 is disengaged from the driving disk 31 and coupled with the braking disk 40, rotating at reduced speed, by release and return of the starting lever 42 to its rest position shown in the drawing. As a consequence, the operating speed of the sewing machine is reduced considerably compared with the rotating speed of shaft 30, resulting thereby in the slow rotation of the braking disk 40 until the brush B of the slip ring 4 engages the insulating segment 8 in the needle DOWN position and simultaneously the

contacts

65 and 67 of the control switch 64 become disengaged in the right stitching position of the needle. As soon as the latter position has been reached, relay 51 is de-energized, whereby to connect the magnet 50 of the braking member 49 by the relay contact 52 engaging the contact arm 54. This will result in the instant braking of the auxiliary drive and the safe stoppage of the sewing machine in the needle DOWN and RIGHT stitching position.

During the operation of the sewing machine by the auxiliary (slow-running) drive, the task of the control switch 64 is to maintain the control circuit of the auxiliary drive closed in the LEFT stitching position of the needle, while brush B engages segment 8, and to interrupt said circuit in the RIGHT needle stitching position, respectively, during the interval when the brush B of the slip ring 4 engages the insulating segment 8 in the needle DOWN position.

The design of the control switch 64 in the form of a double-pole changeover switch and its connection with the selector switch 74 in the manner shown, makes it furthermore possible to arrest the sewing machine in the LEFT stitching position with the needle in its DOWN position. For this purpose, all that is required is to operate the selector switch 74 from contact '73 to engagement with its contact 71. In the latter position, the control switch 64 by-passes, during the non-desired or right stitching positions of the needle, the control circuit of the auxiliary drive while being interrupted by the segment 8 in the needle DOWN position during a machine stoppage operation. As a consequence, the machine continues to rotate until reaching the needle DOWN position in the LEFT stitching position, thus interrupting the circuit and cansing the deenergization of relay 51. This again results in the energization of the braking magnet 50 via relay contact 52, thus braking the auxiliary drive and safely stopping the machine in the needle DOWN and LEFT stitching position.

The same operation obtains in stopping the machine, in either the RIGHT or LEFT stitching position, with the needle in the UP position, after closing of the contacts 78 of the changeover switch 76.

In the embodiment according to FIG. 2, the synchronizer 82, driven, via bevel gears 87, 88, at half the speed of the rotating speed of shaft 3 assumes the function of the control switch 64 of FIGURE 1.

The design of the synchronizer 82 is such that, in the needle DOWN position and within the region between the center needle and right needle stitching positions, the brush B of the slip ring 83 is opposite its insulating segment 89 and that, in the needle DOWN position and within the region between the center needle stitching and LEFT needle stitching positions, the brush B of the slip ring 85 is opposite its insulating segment 90. As described hereinbefore, stoppage of the sewing machine, at the completion of a sewing operation, is initiated by the operation or release of the control lever 42 to its rest position and establishment of driving connection between coupling disk 44 and braking disk 40, whereby to brake the machine to a considerably reduced speed compared with its normal operating speed. Provided the switches 74 and 76 are in the position shown in FIG. 2, the sewing machine is rotated at reduced operating speed by the braking disk 40 until the brush B of slip ring 4 engages, in the DOWN position of the needle, the insulating segment 8 and at the same time the brush B of the slip ring 83 engages the insulating segment 89 in the right stitching position of the needle. As soon as the latter position has been reached, relay 51 is deenergized and the braking magnet 50 connected by the contact arm 54 engaging relay contact 52, whereby to instantly brake the auxiliary drive and to safely arrest the sewing machine in the needle DOWN and RIGHT zigzag stitching position.

While the sewing machine is driven by the auxiliary drive at reduced speed, the slip ring 83 of the synchronizer 82 by-passes the control circuit of the drive in the non-desired or left needle stitching positions, that is, while the brush B of the slip ring 4 engages the insulating segment 8 in the needle DOWN position, thus interrupting the circuit by the segment 89 at the instant of reaching the right stitching position of the needle.

In order to arrest the sewing machine in the needle DOWN and LEFT stitching positions, the arm of the changeover switch 74- is connected with the contact 71 in the manner described hereinbefore. In this position, the control circuit of the auxiliary drive, being interrupted during the DOWN positions of the needle by the segment 8, is by-passed, by the slip ring 85 of the synchronizer 82, in the non-desired or right needle stitching positions and with the needle in the DOWN position, whereby to enable the sewing machine to perform one more revolution by its drive shaft 3. The control circuit of the auxiliary drive is then interrupted by both insulating segments 8 and 99, as soon as the needle has reached its DOWN and LEFT stitching position, whereupon relay 51 is again de-energized and the braking magnet 50 connected by the contact arm 54 engaging relay contact 52, in the manner described hereinbefore.

As a result of the cooperation described between the

control switch

64 or 82, the selector switch 74 changeover switch 76 and the synchronizer 7 of the zigzag control mechanism of the sewing machine, it is possible to stop the machine, after proper setting of the switches 74 and 76 in either of the needle DOWN and UP positions, and selectively in the RIGHT and LEFT zigzag stitching DOWN positions, to suit any existing operating conditions and requirements.

In the foregoing the invention has been described in reference to an exemplary device or embodiment. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts or elements for those shown herein for illustration, may be made without departing from the broader purview and spirit of the invention. The specification and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.

We claim:

1. In a zigzag sewing machine including a rotating drive shaft, a continuously running driving motor, main drive means between said motor and said shaft, a reciprocatory and oscillatory needle bar carrying a sewing needle, first motion-transmitting and converting means between said shaft and said bar to vertically reciprocate said bar at normal needle operating speed, and second motiontransmitting and converting means between said shaft and said bar, to horizontally oscillate said bar for the formation of zigzag stitches in the work operated on by the combined reciprocating and oscillating movement of said needle; the improvement consisting in the provision of automatic motion stoppage means comprising in combination:

(1) auxiliary drive means between said motor and said shaft to operate the machine at a reduced speed compared with the normal needle operating speed,

(2) electrically operable control means having an operating circuit to connect said auxiliary drive means while simultaneously disconnecting said main drive means, and vise versa,

(3) a periodic timing switch synchronized with the reciprocating movements of said bar, said switch being connected in said operating circuit and adapted to open said circuit and to arrest said machine driven by said auxiliary drive, at a predetermined vertical needle position,

(4) a periodically operated control switch synchronized with the horizontal oscillating movements of said bar, and

(5) circuit connections between said control switch and said timing switch, to by-pass and disable said timing switch by said control switch during the horizontal oscillating excursions of said bar in one direction from the central needle stitching position and to suspend the by-pass by said control switch and to restore the operativeness of said timing switch during the horizontal oscillating excursions of said bar in the opposite direction from said center needle stitching position, respectively.

2. In a zigzag sewing machine as claimed in claim 1, said control switch being a two-pole switch, and a twopole selector switch connected thereto and to said timing switch, to selectively by-pass said timing switch during either of the oscillating excursions of said bar in dependence upon the position of said selector switch.

3. In a zigzag sewing machine as claimed in claim 2, said second motion-transmitting and converting means including an oscillating shift bar actuating said needle bar, and said control switch consisting of a vibratory reed contact mounted in a hermetically sealed space, a pair of fixed contacts within said space for cooperation with said reed contact, and a permanent magnet actuator mounted upon said shift bar, to proximity-control said reed contact from the outside of said space.

4. In a zigzag sewing machine as claimed in claim 1, said timing switch consisting of a slip ring having a contact brush cooperating therewith and means to rotate the same by said drive shaft, and a peripheral insulating segment upon said ring, to interrupt the electrical connection between said ring and brush at a predetermined needle position.

5. In a zigzag sewing machine as claimed in claim 1, said timing switch consisting of a slip ring having a contact brush cooperating therewith and means to rotate the same by said drive shaft, a peripheral insulating segment upon said ring, to interrupt the electrical connection between said ring and brush at a predetermined needle position, and said control switch consisting of a further slip ring having a contact brush cooperating therewith and means to rotate the same by and at half the rotating speed of'said drive shaft, said further slip ring and brush bypassing said first slip ring and brush and having a peripheral insulating segment positioned to be engaged by its brush simultaneously with the engagement of the insulating segment and brush of said first slip ring.

6. In a zigzag sewing machine including a rotating drive shaft, a continuously running driving motor, main drive means between said motor and said shaft, a reciprocatory and oscillatory needle bar carrying a sewing needle, first motion-transmitting and converting means between said shaft and bar to vertically reciprocate said bar at normal needle operating speed, and second motion-transmitting and converting means between said shaft and said bar to horizontally oscillate said bar for the formation of zigzag stitches in the work operated on by the combined reciprocating and oscillating movements of the needle, the improvement consisting in the provision of automatic motion stoppage means comprising in combination:

(1) auxiliary drive means between said motor and said shaft to operate said bar at reduced speed compared with the normal needle operating speed,

(2) electrically operable control means having an operating circuit to connect said auxiliary drive means while disconnecting said main drive means, and vice versa,

(3) a pair of periodic timing switches synchronized with the vertical reciprocating movements of said bar,

(4) selector switch means to selectively connect said timing switches in said operating circuit, each of said timing switches operating to arrest said machine while 13 being driven by said auxiliary drive at, respectively, first and second predetermined needle positions,

( a periodically operated control switch synchronized with the horizontal oscillating movement of said bar, and

(6) circuit connections between said control switch and said timing switches, to by-pass the connected timing switch during the horizontal oscillating excursions of said bar in one direction from the central needle stitching position, and to suspend the by-pass by said control switch and to restore the operativeness of the respective timing switch during the horizontal oscillating excursions of said bar in the opposite direction from said central needle position, respectively.

7. In a zigzag sewing machine as claimed in claim 6, said control switch being a two-pole switch, and a second two-pole selector switch connected to said first selector switch and said timing switches, to selectively by-pass either timing switch during a desired one of the horizontal excursions of said bar by operation of said second selector switch.

8. In a zigzag sewing machine as claimed in claim 7, said second motion-transmitting and converting means including an oscillating shift bar actuating said needle bar, and said control switch consisting of a vibratory reed contact mounted in a hermetically closed vessel, a pair of fixed contacts within said vessel for cooperation with said reed contact, and a permanent magnet actuator mounted upon said shift bar, to operate said reed contact.

In a zigzag sewing machine as claimed in claim 6, said timing switches consisting of a pair of slip rings having cooperating contact brushes and driven by said drive shaft, said slip rings provided with insulating segments for engagement by said brushes and displaced by to selectively arrest said machine in the needle DOWN and UP positions, respectively.

10. In a zigzag sewing machine as claimed in claim 6, said timing switches consisting of a pair of slip rings having cooperating contact brushes :and driven by said drive shaft, said slip rings provided with insulating segments for engagement by said brushes and displaced by 180, to selectively arrest said machine in the needle DOWN and UP positions, respectively, and said control switch consisting of a pair of further slip rings having cooperating brushes and means to drive the same at half the rotating speed of said drive shaft.

References Cited UNITED STATES PATENTS 2,914,010 11/1959 Cohen. 3,174,450 3/1965 Becker et al.

H. HAMPTON HUNTER, Primary Examiner US. Cl. X.R.