US3688714A

US3688714A - Control system for a sewing machine

Info

Publication number: US3688714A
Application number: US63249A
Authority: US
Inventors: Tsutomu Makihara; Satoshige Yoneji
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 1969-08-12
Filing date: 1970-08-12
Publication date: 1972-09-05
Anticipated expiration: 1989-09-05

Abstract

A system comprises a sewing machine, a clutch-brake motor for driving said sewing machine at high speed, a foot treadle, and an electric circuit for controlling the machine operation. The machine is operated by the circuit in such a manner that nonraveling seam is applied at the end of lock stitch seam at high speed when the foot treadle is operated.

Description

United States Patent Makihara et al. 1 Sept. 5, 1972 [54] CONTROL SYSTEM FOR A SEWING [56] References Cited MACHINE UNITED STATES PATENTS [72] Inventors: Tsutomu Makihara, Kariya;

satoshige j g y both of 3,363,594 H1968 KOSl'OW. ..1 12/210 Japan 3,174,450 3/1965 Becker et ..1 12/219 A 3,024,750 3/1962 Winz ..112/203 [73] Ass1gnee: Brother Kogyo Kabushlkl a fl, 3,307,510 3/1967 Hedegaard et al.....l 12/219 A Nagoya-shi, Japan Primary Examiner-11. Hampton Hunter [22] Flled' 1970 Au0meyKemon, Palmer & Estabrook [21] Appl. No.: 63,249 v [57] ABSTRACT [30] Foreign Application Priority Data A system comprises a sewing machine, a clutch-brake motor for driving said sewing machine at high speed, a 1969 Japan "44/63976 foot treadle, and an electric circuit for controlling the machine operation. The machine is operated by the [52] y' 'g circuit in such a manner that non-raveling seam is ap- Z Fq i R 219 B plied at the end of lock stitch seam at high speed when 1 o m the foot treadle is operated.

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nun-om mAKmAnA CONTROL SYSTEM FOR A SEWING MACHINE The present invention relates to a control system for a sewing machine including non-ravel seaming device which can quickly and automatically make non-raveling seam at the start and terminal ends of sewing operation.

The conventional non-ravel seaming process at the start of sewing consists in light depressing a foot treadle connected to a clutch and brake motor to slow down the sewing speed of the sewing machine and under this condition continuing sewing up to a desired point, manually actuating a work feed reversing mechanism to sew the work fabric over a slight length under such condition, releasing the work feeding reversing mechanism to bring the work feed back to the original direction and upon completion of the non-ravel seaming properly depressing the foot treadle to perform the desired normal sewing. Also the non-ravel seaming process at the end of sewing consisted in stopping the depression of a treadle connected to the clutch and brake motor of a sewing machine as sewing is drawn near its termination so as to slow down the sewing speed, thereby reliably carrying out sewing up to the desired point, manually operating a work feed reversing means to sew only a small portion of the work at reverse feed, releasing said work feed reversing means to bring the work feed back to its normal direction and perform sewing again at normal feed.

The aforesaid conventional non-ravel seaming process had the drawbacks that there was not only required manual operation each time non-ravel seaming was conducted until one cycle of sewing was completed, but also operating efficiency was reduced because sewing speed has to be slowed down. Moreover, since the amount of non-rave] seaming was determined by the length of time the treadle was depressed, as well as by the period and time a work feed reversing mechanism is operated there resulted irregular or in some cases unduly insufficient non-ravel seaming. Also lowering in commercial value of the finished articles resulted.

The primary object of the present invention is to provide a control system for a sewing machine, capable of performing an automatic non-rave] seaming, at the start and end of sewing, by the operation of a foot treadle. The other object of the present invention is to provide a control system for a sewing machine capable of performing an automatic non-ravel seaming at high speeds and without involving any slowdown of sewing speeds, and capable of enhancing the efficiency of sewing operation. The further object of the present invention is to provide a control system for a sewing machine, capable of performing an automatic nonravel seaming of predetermined length at the start and end of sewing to obtain a uniform seam of non-ravel sewing without involving the lowering in commercial value of the finished article. Still further object of the present invention is to provide a control system for a sewing machine, capable of stopping the needle in an upper position subsequent to a non-ravel seaming performed in the terminal end of the work fabric after the end of a series of sewing operations, and operating a thread cutting mechanism whereby the efficiency of operation can be more enhanced. Still further object of the present invention is to provide a control system for a sewing machine, capable of attaining the above objects with a simpler construction and in a form suitable for purposes.

This invention can be more fully understood from the following detailed description given by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a schematic pictorial view of an entire sewing machine according to an embodiment of the present invention which is equipped with a. clutch and brake motor;

FIG. 2 schematically presents the drive mechanism of said sewing machine;

FIG. 3 is an elevation, partly broken away, of a clutch and brake motor;

FIG. 4 is a bottom view of the operating mechanism of the clutch and brake motor of FIG. 3;

FIG. 5 is a cross sectional view taken on line 5-5 of FIG. 3;

FIG. 6 is a cross sectional view of an auxiliary motor attached to the clutch and brake motor of FIG. 5;

FIG. 7 is a cross section of the foot treadle of the sewing machine of FIG. 1;

FIG. 8 is a cross sectional view of the ring switch mechanism of the sewing machine of FIG. 1;

FIG. 9 is a cross sectional view of the individual ring switches where the switch mechanism of FIG. 8 is dismembered;

FIG. 10 illustrates the relative positions of the ON and OFF regions of the respective ring switches;

FIG. 11 is a schematic pictorial view of the work feed mechanism of the sewing machine of FIG. 1;

FIG. 12 indicates an electrical control circuit for driving the sewing machine of FIG. 1;

FIG. 13 is a time chart for explanatory illustration of the sewing machine operation; and

FIGS. 14A and 14B show a modification of an actuating lever structure of the sewing machine.

Referring to FIGS. 1 and 2, the reference numeral 20 denotes a sewing machine, and 21 is its main shaft, rotatably supported on the frame of said sewing machine 20 The main shaft is fitted with a pulley 22 and ring switch assembly 23 as will be later set forth. 24 is a reciprocable needle supported on the frame and drivingly connected to the

main shaft

21 and 25 is a presser foot urged downward by a built-in spring 26. Said font 25 is coupled with an interlocking mechanism 30 consisting of a lever 27, connection rod 28, and bell crank 29. The interlocking mechanism 30 is connected to the piston rod 32 of a fluid pressure cylinder 31. 33 is an electrical control valve attached to the first fluid pressure cylinder 31 so as to transfer fluid stream. Said electrical control valve 33 is actuated upon energization by a first solenoid 34 to lift the presser foot 25 and keep it at an upper position. 40 is a thread cutting mechanism rockably fitted to the underside of a throat plate, which is connected to the piston rod 36 of a second fluid pressure cylinder 35. 37 is an electrical control valve attached to the second fluid pressure cylinder 35 so as to transfer fluid streams. On both sides of said valve 37 are disposed second and

third solenoids

38 and 39 which are alternately energized. Movement of the piston rod 36 upon energization by the second solenoid 38 causes the thread cutting mechanism 40 to rock one way to take hold of upper and lower threads, while movement of the piston rod 36 resulting from energization by the third solenoid 39 causes the thread cutting mechanism 40 to rock the other way so as to cut thread.

A clutch and brake motor as shown in FIGS. 2 to 6 includes a main motor 41 disposed in a bracket 42, which consists of a stator 43 and rotor 44. One end of the rotary shaft of the rotor 44 extends through a bearing 46. To the projecting end of said rotary shaft 45 is fixed by a bolt 48 a flywheel 47 fitted with a friction plate 56. 49 is a hollow bearing cylinder received in an end bracket 50 in coaxial relationship with the retary shaft 45.

With the periphery of the bearing cylinder 49, FIG is rotatably engaged an annular worm wheel through a bearing 51. 52 is a brake wheel having a friction plate 53 fitted on one side. This brake wheel 52 is connected by bolt 54 to that side of the worm wheel 55 which faces the flywheel 47. 58 is a movable shaft supported to a sleeve 57 journaled in the bearing cylinder 49 so as to slide therethrough in its axial direction. To the inner end of said shaft 58 is connected by a bolt 61 a clutch disk interposed between the friction plates 52 and 56. To the outer end of said shaft 58 is connected a pulley 62 by a bolt 63. is an auxiliary motor, FIG. 6 which consists of a stator 71 and rotor 72. One end of the shaft 77 of the rotor 72 is supported on one end bracket 73 through a bearing 74 and the other end of said shaft 77 projects through a bearing 76 from the other end bracket 75. Outside of the end bracket are provided inner and outer chambers 78 and 79 partitioned by a double cylindrical wall disposed around the rotary shaft 77. To that end of the rotary shaft 77 which projects into the inner chamber 78 is fixed by bolt 82 a connection wheel 81 having a friction engaging member fitted to its side. In the outer chamber 79 is received a clutch coil 83, for example, an annular solenoid. 84 is a clutch side bracket connected to the

end bracket

75 and 85 is a worm gear side bracket connected to said clutch side bracket 84 by a bolt 86. The latter bracket 85 is integrally formed with the end bracket 50 facing the main motor 41. 87 is a worm gear engaging the worm wheel 55. One end of a shaft 88 integrally formed with said worm gear 87 is pivoted to the outer end of the bracket 85. The other end of said shaft 88' is inserted into the clutch side bracket 84 with the intermediate portion supported by a bearing 89. 90 is a coil case received in the clutch side bracket 84 so as to surround the shaft 88. This coil case 90 having a side contact member 93 houses a brake coil 140, and an attractive plate 91 and is connected by a bolt 92 to the clutch side bracket 84. 94 is a clutch disk fitted with a brake member 95 slidable on the shaft 88 in the axial direction thereof. Said clutch disk 94 is interposed between the friction engaging member 80 of the connection wheel 81 and the contact member 93 and is connected to the end of the shaft 88 so as to move in it axial direction. As shown in FIG. 3 is a main actuating lever assuming as a whole an L-shape. The two portion divided by the bent point are designated as one arm 101 and the other arm 102 respectively. From the bend of said main actuating lever 100 projects a twoforked pressure contact means 103a comprising a pressure contact member 103. The end of said one arm 101 is rotatably supported by a shaft pin 105 on a support member 104 projecting from the end bracket 50. 106 is a spring support rod freely penetrating said one arm 101, one end of said rod 106 being fixed to the end bracket 50. Into the end bore of said one arm 101 penetrated by the spring support rod 107 is idly inserted a coil spring so as to press said one arm 101. Said spring 107 is kept in a compressed state by screwing a wing nut 108 onto the end of the spring support rod 106. 109 is a limit stop arm screwed through said arm 101. The end of said stopper 109 normally contacts the end bracket 50 and is prevented from being loosened by a nut 110. 111 is an intermediate lever whose cross section substantially assumes a horizontally disposed U-shape. Said lever 11 1 is pivotally connected at a certain point along its length to the end of said other arm 102 by a shaft pin 112. Substantially to the right side and adjacent the end of said lever 11 1 as shown inFIG. 4 is fitted by a screw 114 a thread cutting switch s comprising an actuating strip 113. 1 15 is a coil spring, part of which is received in a recess 1 16 formed in said other arm 102. The upper end of said coil spring 115 contacts the underside of the end of the intermediate lever 111. Said coil spring 115 is guided by a bolt 117 extending freely through the end of the intermediate lever 111, said bolt 117 being embedded in said other arm 102. 118 is a stopper penetrating throughout the intermediate lever 111. The lower end of the stopper 118 contacts the end of said other arm 102. 119 is an actuating plate which is fixed by screw 120 to the end of said other arm 102 in such a manner as to face the actuating strip 1 13 of the thread cutting switch S Into that part of said actuating plate 1 19 which faces the actuating strip 113 is inserted a press screw 121. 122 is an auxiliary actuating lever consisting of a pair of plate members surrounding said one arm 101 of the main actuating lever 100, the intermediate part of said lever 122 being rotatably pivoted to the shaft pin 105. The upper end of said lever 122 is connected through an opening 123 formed in the underside of the bearing cylinder 49 to a shaft pin 124 engaging the annular groove 59 of the sleeve 57. To the lower end of the auxiliary actuating lever 122, FIG. 4, is horizontally fitted another shaft pin 125. The shaft pin 125 is contacted by the press member 103 of the main actuating lever 100. As shown in FIG. 4 126 is a connection member rotatably connected to the shaft pin 125 and there is interposed a coil spring 128 in a compressed state between one end of said connection member 126 and a spring support 127 substantially assuming a horizontally thrown U-shape which is fixed to the main actuating lever 100. 129, FIG. 3, is a fluid pressure cylinder including a fourth solenoid 129a. When there is introduced high pressure fluid into the fluid pressure cylinder 129 upon energization of the solenoid 129a, the piston rod 130 of which is pushed forward. The fluid pressure cylinder 129 is fitted through a support plate 131 below said other arm 102 of the main actuating lever 100 by a shaft screw 132 in a manner to rotate about it. The end of the piston rod 130 is integrally connected to the other end of the connection member 126. 134 as shown in FIG. 1 is a font treadle positioned below a sewing machine bed. The treadle 134 is fitted with a connection rod 136 the upper end of which is connected to the end of the intermediate lever 111. Said foot treadle is normally positioned in a rest position and operable in a downward direction by depression of the toe of the operator to actuate the main actuating lever 100, and in any upward direction beyond the rest position by the heel of the operator. Into the lower end of the auxiliary actuating lever 122 is inserted a press screw 142, in FIG. 4, in a manner to penetrate it. The screw 142 is prevented from being loosened by a nut 143. S denotes a start switch fitted to a support 175 mounted on the bracket 50. The start switch S is normally opened with its actuating strip 146 pressed by the press screw 142, and closed when the actuating strip 146 is released.

There will now be described the operation of a clutch and brake motor constructed as above described. Let it be assumed that the main motor 41 and auxiliary motor 70 FIG. 2, are brought into an operable state without any manual operation applied to the main and the

auxiliary levers

100 and 122. Since the brake member 52 and clutch disk 60 are separated, the flywheel 47 continues no-load rotation. On the other hand, where, on the side of the auxiliary motor 70, the clutch coil 83 is excited, FIG. 6, the clutch disk 94 frictionally engages the friction engaging member 80 of the connection wheel 81 to cause the worm gear 87 to rotate, and in consequence the worm wheel 55 engaging the worm gear 87 slowly rotates around the bearing cylinder 49. Under such condition, namely, where the foot treadle 134 is not depressed but keeps a neutral position, the clutch disk 60 on the side of the main motor 41 is pressed, as described later, to the friction plate 53 of the worm wheel 55 by the action of the coil spring 107 and 128. Accordingly, the rotation of the worm wheel 55 is transmitted to the pulley 62 through the clutch disk 60 and movable shaft 58. At this time, the pulley 62 is in a slowly rotating state. When, under such condition, the foot treadle 134 is depressed in the downward direction (that is, toward the start side), then the intermediate lever 111 is pulled downward through the connection rod 136, and the other arm 102 of the main actuating lever 100 is depressed by the joint action of the stopper 118 and shaft pin 112 of said intermediate lever 111 to rotate about the shaft pin 105 in the direction indicated by the arrow 137, FIG. 3. As a result, the press contact member 103 presses the shaft pin 125, causing the auxiliary actuating lever 122 to rotate about the shaft pin 105 similarly in the direction indicated by the arrow 137. Accordingly, the sleeve 57 moves through the shaft pin 124 in the direction indicated by the arrow 138, carrying with it the movable shaft 58, so that the clutch disk panel 60 is pressed to the friction plate 56 of the flywheel 47 which is rotating without load and is frictionally coupled with said wheel 47, with the resultant high speed rotation of the pulley 62. In the aforesaid operation, the coil spring 107 supplies the main actuating lever 100 with a force to rotate opposite to the direction indicated by the arrow 137. The other coil spring 128 supplies the auxiliary actuating lever 122 with a force to rotate similarly opposite to the direction of the arrow 137. When the foot treadle 134 is released, the clutch disk 60 is pressed to the side of the worm wheel 55. Where the brake coil 140 of the auxiliary drive is excited while the pulley 62 slowly rotates, the clutch panel 94 is attracted thereby and the brake member 95 of said disk 94 slides to the slide contact member 93 so as to effect braking, with the resultant stop of the pulley 62. The clutch and brake motor can be controlled by means of the fluid pressure cylinder 129. The electrical control valve of the fluid pressure cylinder 129 is energized to conduct high pressure fluid into the cylinder to cause the piston rod 130 of said cylinder 129 to be pushed forward, to rotate the auxiliary actuating lever 122 in the direction of arrow 137, FIG. 3, when the foot treadle 134 is operated in the upward direction beyond the rest position. When the electrical control valve is deenergized, the'high pressure fluid ceases to be supplied, causing the auxiliary actuating lever 122 to be returned by the action of the coil springs 107 and 128. The coil spring 1 15 serves to energize the intermediate lever 111 for its rotation about the shaft pin 112 in the direction of the arrow and 147 and also normally to leave the thread cutting switch 8;, open by causing the press strip 113 to contact the press screw 121.

There will be described a modification of the actuating lever structure with reference to FIGS. 14A and 14B.

FIG. 14A shows normal operating conditions while FIG. 14B a non-raveling seaming operation.

The apparatus includes a main actuating lever 338 associated with the foot treadle, which is swingable around an axle 339. The cutting portion 340 formed at one end of the lever 338 is abruptly stopped by a fixed axle 342 projected from a displacement body 341 through which the axle is loosely inserted. Numeral 343 denotes an auxiliary actuating lever pivoted on the axle 339, one end of the lever 343 being connected to the fixed axle and the other end to a piston rod 345 of pressure cylinder 344 mounted on the actuating lever 338. 346 shows an actuator of the cylinder 344 where there are provided two

solenoids

348 and 349 alternatively operating. Numeral 347 denotes a coil spring provided between both

levers

338 and 343 in such a manner that it urges both levers to swing them in the opposite directions. Reference P is a pressure Source In the apparatus there is a switch, though not shown in the figures, which starts the machine operation when the foot treadle is operated in the upward direction beyond the rest position.

The foot treadle 134 is provided, as shown in FIG. 7, with a normally closed switch S for lifting the pressure foot which is turned off prior to the operation of the switch S in the initial stage of the depression of the foot treadle 134 in the downward direction and a thread cutting switch S for closing the thread cutting control circuit which is turned on by the operation of the foot treadle 134 in the upward direction beyond the rest position. The switch S is disposed on the underside of an auxiliary treadle 134 a consisting of, for example, a flexible plate which is located at the rear part of the foot treadle. 134. Where the foot treadle is not depressed either way, that is, is left in an inoperable state, the main actuating lever 100 causes the clutch disk 60 to contact the brake wheel 52.

There will now be described the ring switch assembly 23 mounted on he main shaft 21 of the sewing machine which acts as a mechanism for arresting the needle at a prescribed position with reference to FIGS. 8 and 10 where the needle is brought down. The ring switch assembly 23 consists of a common ring 150 fixed on the main shaft 21, a thread cutting position detecting ring 151 wherein a periphery extending through about 300 is designated as an OFF region, a needle upper position detecting ring 152 wherein a periphery of about 60 is defined as an OFF region, and a needle lower position detecting ring 153 whose OFF region is represented by a periphery of about 17. The phases of the ON and .OFF regions of the

other rings

151, 152 and 153 are so adjusted as to have a relation shown in FIG. 10. The

rings

151, 152 and 153 are contacted by

brushes

151a, 152a and 153a to constitute a thread cutting position detecting contact 8,, needle upper position detecting contact 8, and needle lower position detecting contact S, respectively.

Referring to the work feed mechanism shown in FlG. 1 1, the reference numeral 160 denotes a two-forked rod engaged at one end with the work feed cam 161 of the main shaft 21 and at the other end with a horizontal work feed advancing shaft 162. This shaft 162 rocks by the rotation of the work feed cam 161. 163 is a work feed bar provided with a feed dog 164. Said work feed bar 163 is connected at one end to the horizontal work feed advancing shaft 162 so as to rock horizontally, and at the other end to a pendulum 166 mounted on a vertical feed lifting shaft 165 in a manner to rock vertically. When the horizontal feed advancing shaft 162 and vertical feed lifting shaft 165 rock, the feed dog 164 makes four feed motions by a composition of said rockings to perform a work feed action. A feed reversing means involved in the work feed mechanism is operated in the following manner. 167 is a feed adjusting means disposed at the fulcrum of the two-forked rod 160 and provided with a dial 167a for controlling the work feed. To said feed adjusting means 167 is connected the feed reverse arm, 170 of a reversing shaft 169 provided with a reversing lever 168. When this reversing lever 168 is pushed down, the feeding direction of said dog 164 is turned from a forward to a backward movement on the bed of a sewing machine. 171 is a fourth fluid pressure cylinder rockable supported by a pin 173 on a support member 172 fitted to the underside of said machine bed. The piston rod 174 of the cylinder 171 is connected to an arm 175 fixed to the reversing shaft 169. To the arm 175 is connected a spring member 176 for urging the reversing shaft 169 in an opposite direction. 177 is an electrical control valve for transferring fluid streams which is attached to the fourth fluid pressure cylinder 171. The electrical control valve 177 is provided with a fifth solenoid 178, which, when energized, feeds fluid streams in a direction of pushing up the piston rod 174. Energization of the solenoid 178 causes the piston rod 174 to be forced upward, the reversing shaft 169 to rotate in an opposite direction and the feed dog 164 to move backward. 179 is a source of compressed fluid, for example, a compressor.

There will now be described with reference to FIG. 12 an electrical control circuit to effect the proper function of the entire sewing machine mechanism. The reference numeral 181 is a transformer, whose primary winding 182 is connected to an A.C. source 183. Both end of the secondary winding 184 of the transformer 181 are connected to two buses or power source lines 183 and 186 through one full wave rectifier 185. Across the power source lines 186 and 187 is a smoothing circuit consisting of a resistor 188 and condenser 189 connected in series. The circuit energized by the voltage impressed across the power source lines is arranged as follows. Across the power source lines is connected a serial circuit consisting of the start switch S diode 191 and relay 190 energized through the diode 191 by the closure of the switch S Across the cathode of the diode 191 and the first power source line 186 is connected a serial circuit comprising the normally open contact element 190a of the relay 190 and a needle lower position detecting contact element S Thus these serial circuits constitute the self-holding circuit of the relay 190. Parallel with the needle lower position detecting element S, is connected a serial circuit consisting of a condenser 192 and diode 193 for preventing inverse discharge, to which there is connected a resistor 194. 195b, is the normally closed contact element of the later described thread cutting relay 195, one end of which is connected to the first line 186 and the other end of which is connected to a control line 197 through the normally open side of the switching contact element 196e, of the later described relay 196. Across the control line 197 and the anode of the diode 191 are connected a three-terminal thyristor 198 and start non-rave! seaming switch S Accordingly, the control line 197 is supplied with power by the first power source line through the start switch S and element 8,; and 198. Between the control line 197 and second line 187 are connected a serial circuit consisting of the relay 196 and three-terminal thyristor 199 and a simulation load 200. 201 is another control line connected to said control line 197 through the normally closed side of the switching contact element 196e,. Between the control line 201 and second line 187 is disposed a timer device 202 energized by the voltage prevailing therebetween so as to set the time of reversion.

The timer device 202 is intended to actuate the work feed reversion mechanism in a prescribed length of time after the start of a sewing machine. Said timer device 202 is arranged as follows. Between the control line 201 and second line 187 is connected a serial circuit consisting of a resistor 203 and constant voltage diode 204. Parallel with said diode 204 is connected a time constant circuit consisting of a resistor 205, variable resistor 206 and condenser 207 connected in series. Further parallel with the diode 204 is connected a unijunction transistor 209, through

resistors

210 and 21 1 connected to the base regions of the transistor. The emitter of the transistor 209 is connected to the juncture between the variable resistor 206 and condensor 207. Accordingly, the transistor 209 is energized by a voltage prevailing across both terminals of the constant voltage diode 204. Between the control line 201 and second line 187 are connected in series a relay 213 and three-terminal thyristor 212. The gate of the thyristor 212 is connected through a diode 214 to the juncture between the transistor 209 and resistor 211. Thus the diode 214 is energized by a voltage prevailing across the terminal of the resistor 211.

With the timer device 202 of the aforementioned arrangement, when the control line 201 is impressed with a voltage, the condenser 207 begins to be charged. When the terminal voltage of the condenser 207 attains a prescribed value after a preset time (as determined by the resistivities of the

resistors

203, 205 and 206 constituting a time constant circuit), then the transistor 209 is conducted and the thyristor 212 is also con- 9 ducted by being supplied with gate signals through the diode 214 to actuate the relay 213.

The reference numeral 215 indicated in the circuit denotes a reversion timer device concurrently acting as the first and second timer devices which set the period during which the work feed and reversion mechanisms are separated when nonravel seaming is performed at the start and end of sewing.

To this reversion timer device, there is connected between the buses 186 and 187 a serial circuit consisting of the fifth solenoid 178 and transistor 226. Between the control line 201 and second line 187 are connected the normally open contact element 2130 of the relay 213, a diode 217 and a resistor 252. To the cathode of the diode 217 is connected further control line 216, to which there is connected one end of still further control line 218 through a resistor 219. To the other end of the control line 218 are connected in turn a resistor 220, two

variable resistors

221 and 222 alternately actuated by the switching contact element 2130 of the relay 213 and a condenser 223 connected to said

resistors

221 and 222, thus constituting a time constant circuit. The reference numeral -224 is a unijunction transistor, one base of which is connected to the control line 218 through a resistor 225, the other base of which is connected to the second line 187 through the primary winding PT of a first pulse transformer PT,, and the emitter of which is connected to the juncture between the

resistors

221 and 222 and the condenser 223. As the result, the emitter is energized by a voltage impressed across the condenser 223, thereby causing the transistor 224 to be conducted in a prescribed length of time. Between the cathode of the diode 217 and second line 187 is connected a serial circuit consisting of a resistor 228 and three-terminal thyristor 227. The anode of the thyristor 227 is connected to the base of the transistor 226. The reference numeral 231 shown in the figure denotes a constant voltage diode interposed between the control line 218 and second line 187. 253 and S respectively represent a diode connected between the

lines

186 and 187 and a manual switch for manually operating the work feed and reversion mechanisms. Further between the power source lines 186 and 187 is connected a serial circuit consisting of a needle upper position detecting contact element V normally open thread cutting switch 3, the normally closed contact element 229b and relay 230 associated with the switching contact element 1900 of the relay 190. The reference numeral 232 denotes further control line, which is connected through the terminal non-rave] seaming switch S to the juncture between the thread cutting switch S and switching contact element 1900,. To the thread cutting switch S is connected in parallel the normally open contact element 233a of the relay 223. Between the control line 232 and second line 187 are respectively connected

relays

233 and 229 energized by a voltage impressed therebetween. Two buses of a transistor 234 are directly connected to said relay 229 and the base 187. To the control line 232 is connected further control line 237 through a three-terminal thyristor 235 and resistor 236. Between the control line 237 and second line 187 is provided a timer device 238 of substantially the same arrangement as the aforementioned timer device 202, which also sets the point of time at which sewing is brought to an end. Referring to said timer device 238, the reference numerals 239 to 242 indicate resistors, 243a condenser, 204 a variable resistor, 244 a unijunction transistor, 245 a diode, and 246 a three-terminal thyristor serially connected to the resistor 242. The anode of the thyristor 246 is connected through a resistor 247 to the base of the transistor 234.

The movable strip of the switching contact element 233c of the relay 233 is connected to the first line 186, and the fixed contact strip on the normally open side of the switching contact element 2330 is connected to the normally open side of the switching contact element 1900,. The brake coil which is connected at one end to-the first line 186 is connected at the other end to the second line 187 through the normally closed side of the switching contact element 190c .of the relay 190 and also through the normally closed side of the switching contact element230c of the relay 230. The clutch coil 83 which is connected at one end to the first line 186 is connected at the other end to the second line 187 through the normally open side of the switching contact element 230e,. The fixed contact element on the normally open side of the switching contact element 233s is connected to the fixed contact element on the normally open side of the switching contact element 1900 To the normally closed side of the switching contact element 2330 are connected the first solenoid 34 and normally closed switch S in turn. The normally closed switch S for lifting the pressure foot is connected to the fixed contact element on the normally closed side of the switching contact element 1900 The reference numeral 229a is the normally open contact element of the relay 229. Between the first and

second lines

186 and 187 is connected a serial circuit consisting of said normally open contact element 229a, and the fourth solenoid 129a serially connected thereto. Further between the power source lines 186 and 187 are connected a serial circuit consisting of the thread cutting position detecting element S thread cutting relay and the normally open contact element 230a, of the relay 230 and another serial circuit consisting of the second solenoid 38, and the normally open side of the switching contact element 195a of the relay 195. The normally closed side of the contact element 195a, is connected to the power source line 186 through the third solenoid 39.

The referencenumeral 248 shown in the figure is a three-terminal thyristor, the anode of which is connected to the first line 186 through the normally open contact element 2290 of the relay 229 and the cathode of which is connected to the control line 216. The reference character PT denotes the primary winding of a second pulse transformer PT Said winding PT is connected at one end to the second line 187 and at the other end is connected to a parallel circuit consisting of a resistor 249 and condenser 250 and to the first line through the thread cutting position detecting element 8,. The two secondary windings designated as PT of the first pulse transformer PT, are connected between the cathodes and gates of the two

thyristors

199 and 227. The three secondary windings indicated as PT of the second pulse transformer PT- are respectively connected between the cathodes and gates of the three

thyristors

198, 235 and 248. 251 denotes the gate bias resistors of the

thyristors

198, 199, 212, 235, 246, 227

and 248;252 is a resistor for assuring power supply to conduct each of the

thyristors

235 and 248;and 253 is a diode for controlling spike voltage.

There will now be described with reference to the time chart of FIG. 13 the non-ravel seaming operating of a sewing machine constructed as described above. The lines of the figure present the operating condition.

(I) Start (Refer to FIG. 13)

When there is thrown the power source switch of the main and auxillary motors (not shown), the motor 40 is brought into an operable state and there is supplied an alternating current from the A.C. source 183 through the transformer 181 to the wave rectifier 185, where the alternating current is subjected to full wave rectification, so that there is impressed a DC. voltage across the power source lines 186 and 187. When the aforesaid power source switch is closed, there are also manually thrown the start and end non-ravel seaming switches S and S Under such condition, the first solenoid 34 is energized through the switch S and the normally closed side of the three switching contact elements 233c 1900 and 230. The piston rod 32 of the first fluid pressure cylinder 31 is urged in a direction of pushing the connection rod 28 to lift the pressure foot 25 against the built-in spring 26. On the other hand, the fourth solenoid 129a for the auxiliary actuating lever 122 is not actuated, so that said control lever 122 is kept parallel with the main actuating lever 100 through spring by the piston rod 85 of the fluid pressure cylinder 84.

(II) Sewing and start non-rave] seaming operation (Refer to T to T in FIG. 13)

When the foot treadle 134 is depressed in a downward direction from the rest position to drive a sewing machine, the switch S is opened by the auxiliary treadle 1340 to deenergize the first solenoid 34, so that the pressure foot 25 is brought down by the spring 26m keep the work on the machine bed. At the time of T of FIG. 13 the start switch S is closed and the main actuating lever 100 rotates about the shaft 105 in he direction of the arrow 137, causing the auxiliary actuating lever 122 to move the sleeve 57 with the movable shaft 58, and the clutch disk 60 to be pressed to the flywheel 47 in high speed rotation. Thus the main shaft 21 is turned quickly to start the sewing operation. When the sewing machine makes such a high speed run, the ring switch assembly 23 is also brought into an operable state. The thread cutting position detecting contact element 8,, needle upper position detecting contact element S and needle lower position detecting contact element 8,, involved in the ring switch assembly 23 are operated with a period shown in FIG. 13. In the meantime the primary winding PT, of the second pulse transformer IT is energized by pulses from the thread cutting position detecting contact element S to generate pulses synchronizing therewith in the secondary winding of the transformer PT On the other hand, the closure of the start switch S causes the relay 190 to be actuated and brought into a self-holding position by the current flowing through the normally open contact element 190a, and needle lower position detecting contact element S In this case, the needle lower position detecting contact element 8.; is turned off each time the brush 153a passes through the OF F region of the needle lower position detecting ring 153. Since, however, the main shaft 21 of the sewing machine is rotated at high speed, the relay 190 is kept in a self-holding position by the current discharged from the condenser 192 during the OFF period of the needle lower position detecting contact element S At this time the switching contact elements 190a, and 190c of the relay 190 are charged over, causing the clutch coil 83 to be excited by the latter contact element l90c Since the clutch disk 94 is attracted to said connection wheel the clutch disk 67 is driven through the worm 87 and worm gear 55 into a slow noload operation. When the sewing operation is reliably started, namely, when the thread cuttingcontact element 8., starts operation to cause pulses to be generated in the secondary winding PT of the second pulse transformer PT then the thyristor 198 is conducted to supply voltage to the

control lines

197 and 201 and energize the timer device 202. AFter a prescribed length of time (at the time T in FIG. 13), the transistor 209 is conducted by the charged current of the condenser 207, with the resultant conduction of the thyristor 212, so as to actuate the relay 213. Accordingly, the variable resistor 222 is selectively operated by the switching contact element 2130 and the reversion timer device 215 is energized by the closure of the normally open contact element 213a,. As the result, the transistor 226 is conducted by the current passing through the resistor 228 to excite the fifth solenoid 178. The piston rod 174 of the fourth fluid pressure cylinder 171 is pushed upward and in consequence the feed dog 164 is changed to make a backward movement opposite to that which it has performed up to this point, so as to reverse the work feed and start non-rave] seaming quickly. This non-ravel seaming is continued until the period preset by the reversion timer device 215 is brought to an end. When the lapse of said period is determined by the time constant defined by the variable resistor 222 and condenser 223, the transistor 224 is conducted to energize the primary winding PT of the first pulse transformer PT, and generate pulses in the secondary winding PT thereof (at the time T in FIG. 13). As the result, the thyristor 227 is conducted and the transistor 226 is shut off to deenergize the fifth solenoid 178, so that the reversing shaft 169 is made to rotate in the normal direction by the spring 176 and the feed dog 164 again starts a forward movement. Upon deenergization of the fifth solenoid 178, the pulses generated in the secondary winding PT of the first pulse transformer PT, conduct the thyristor 199 to actuate the relay 196 and change over the switching contact element 1960,. As the result, the relay 196 is kept in a self-holding position, and power supply to the control line 201 is topped. The relay 213 is brought back to its original position to open its normally open contact element 213a which has been closed up to this point, bringing the control line 216 into an unconducted state, thus preventing the unnecessary restart of the

timer devices

202 and 215. Upon the return of the relay 213, the vari able resistor 221 is selectively actuated by the switching contact element 2130 bringing about a condition preparatory for the end non-ravel seaming. Under such condition normal sewing is continued.

Claims

1. A control system for a sewing machine having a. a frame, b. a main shaft rotatably supported on the frame, c. a reciprocable needle supported on the frame and drivingly connected to said main shaft, d. work feeding means supported on said frame for advancing or reversing the travel of a work fabric according to the rotation of said main shaft, and e. means supported on said frame for reversing the feeding direction of said work feeding means, said control system comprising: 1. drive means drivingly connected to and rotating said main shaft; 2. clutch means provided between said drive means and said main shaft for operatively connecting said drive means with said main shaft; 3. a foot treadle operable from a rest position in a downward direction and in an upward direction beyond the rest position, said foot treadle operably connected to said clutch means and operable in said downward direction for actuating said clutch means to rotate said main shaft; 4. auxiliary actuating means operably connected to said clutch means for actuating the same in replacement of said foot treadle; 5. operating means connected to said auxiliary actuating means for operating the same: 6. a first control means connected to said feed reversing means for actuating the same for a predetermined period upon operation of said foot treadle in the downward direction; and 7. a second control means connected to said operating means and said feed reversing means for actuating both of said means for a predetermined period upon operation of said foot treadle in the upward direction after the desired amount of sewing is finished, whereby there can be effected desired non-ravel seaming automatically and quickly at the start and end of sewing only by the operation of said treadle.

2. clutch means provided between said drive means and said main shaft for operatively connecting said drive means with said main shaft;

2. A control system according to claim 1, wherein said first control means includes a control means operatively connected to said feed reversing means For actuating the same after a predetermined period responsive to the operation of said foot treadle in the downward direction and another control means operatively connected to said feed reversing means for actuating the same for a predetermined period responsive to the completion of the predetermined period of the aforesaid control means.

2. clutch means provided between said drive means and said main shaft for operatively connecting said drive means with said main shaft,

3. a foot treadle operable from a rest position in a downward direction and in an upward direction beyond the rest position, said foot treadle operably connected to said clutch means and operable in said downward direction for actuating said clutch means to rotate said main shaft,

3. A control system according to the claim 1, wherein said second control means includes a control means operatively connected to said feed reversing means for actuating the same for a predetermined period responsive to the operation of said foot treadle in the upward direction and an another control means operatively connected to said operating means for actuating the same for a predetermined period substantially equal to or longer than that of said feed reversing means responsive to the operation of said foot treadle in the upward direction.

3. a foot treadle operable from a rest position in a downward direction and in an upward direction beyond the rest position, said foot treadle operably connected to said clutch means and operable in said downward direction for actuating said clutch means to rotate said main shaft;

4. auxiliary actuating means operably connected to said clutch means for actuating the same in replacement of said foot treadle;

4. A control system according to claim 1, wherein said drive means, said clutch means, said auxiliary actuating means and said operating means constitute a clutch and brake motor assembly for rotating said main shaft, said assembly including: a. a motor having a bracket, b. a flywheel continuously rotated by said motor, c. a brake wheel supported on said bracket, d. a clutch disk operably connected to said main shaft and selectively movable between a first and a second position to be engaged in the first position with said flywheel for transmitting power to said main shaft or in the second position with said brake wheel for stopping the rotation of said main shaft, e. a main actuating lever movably supported on said bracket and operably connected with said clutch disk and said foot treadle for moving said clutch disk between said first and second positions, f. an auxiliary actuating lever movably supported on said bracket for moving said clutch disk in replacement of said main actuating lever, g. a fluid pressure cylinder provided between said main and said auxiliary actuating levers for operating said auxiliary actuating lever responsive to the operation of said foot treadle in the upward direction.

4. auxiliary actuating means operably connected to said clutch means for actuating the same in replacement of said foot treadle,

5. operating means connected to said auxiliary actuating means for operating the same, and

5. operating means connected to said auxiliary actuating means for operating the same,

5. A control system according to claim 4, wherein said main and auxiliary actuating levers are so designed that said main actuating lever moves said clutch disk through said auxiliary actuating lever when said foot treadle is operated in the downward direction, and said auxiliary actuating lever moves said clutch disk independently by the operation of said fluid pressure cylinder when said foot treadle is operated in the upward direction.

5. operating means connected to said auxiliary actuating means for operating the same:

6. a first control means connected to said feed reversing means for actuating the same for a predetermined period upon operation of said foot treadle in the downward direction; and

6. A control system according to claim 4, wherein the main and the auxiliary actuating levers are so designed that the main actuating lever moves the clutch panel independently when the foot treadle is operated in the downward direction, and the auxiliary actuating lever actuates the clutch panel also independently by the operation of the fluid pressure cylinder when the foot treadle is operated in the upward direction.

6. a needle positioning means provided between said drive means and said main shaft for stopping said needle in a predetermined position, and

6. a circuit network interconnecting said feed reversing means and said operating means for actuating the same in response to the operation of said foot treadle, said network including a. a first control circuit operatively connected to said feed reversing means for actuating the same after a predetermined period responsive to the operation of said foot treadle in the downward movement, b. a second control circuit operatively connected to said feed reversing means for actuating the same for a predetermined period responsive to the completion of the predetermined period of said first control circuit, c. a third control circuit connected to said feed reversing means for actuating the same for a predetermined period responsive to thE operation of said foot treadle in the upward direction after the desired amount of sewing is finished, and d. a fourth control circuit connected to said operating means for actuating the same for a period substantially equal to or longer than that of said feed reversing means responsive to the operation of said foot treadle in the upward direction, whereby there can be performed desired non-ravel seaming automatically and quickly at the start and end of sewing only by the operation of said foot treadle.

7. a circuit network interconnecting said feed reversing means, said operating means, said moving means for said thread cutting means and said needle positioning means, said network including a. a first control circuit operatively connected to said feed reversing means for actuating the same for a predetermined period upon operation of said foot treadle in the downward direction, b. a second control circuit for actuating said operating means and said feed reversing means for a predetermined period upon the operation of said foot treadle in the upward direction after the desired amount of sewing is finished, and c. a third control circuit for actuating said needle positioning means and said moving means for said thread cutting means responsive to the termination of the operation of said operating means and said feed reversing means, whereby there can be effected desired non-ravel seaming automatically and quickly at the start and end of sewing, said needle being stopped in a predetermined upper position by said needle positioning means, and said needle thread being cut by said thread cutting means, only by the operation of said foot treadle.

7. A control system for a sewing machine having a. a frame; b. a main shaft rotatably supported on said frame, c. a reciprocable needle supported on said frame and drivingly connected to said main shaft, d. work feeding means supported on said frame for advancing or reversing the travel of a work fabric according to the rotation of said main shaft, e. means supported on said frame for reversing the feeding direction of said work feeding means, f. thread cutting means movably supported on said frame, and g. means supported on said frame for moving said thread cutting means, said control system comprising:

7. a second control means connected to said operating means and said feed reversing means for actuating both of said means for a predetermined period upon operation of said foot treadle in the upward direction after the desired amount of sewing is finished, whereby there can be effected desired non-ravel seaming automatically and quickly at the start and end of sewing only by the operation of said treadle.

8. A control system according to claim 7, wherein said needle positioning means being adapted to arrest said needle in a lower position upon return of said foot treadle to its rest position from the downward direction after the desired amount of sewing is finished.

9. A control system for a sewing machine having a. a frame, b. a main shaft rotatably supported on said frame, c. a reciprocable needle supported on said frame and drivingly connected to said main shaft, d. work feeding means supported on said frame for advancing or reversing the travel of a work fabric according to the rotation of said main shaft, and e. means supported on said frame for reversing the feeding direction of said work feeding means, said control system comprising:

10. A control system according to the claim 9, wherein said second and third control circuits are formed into a single timer circuit capable of setting two different periods for non-ravel seaming.

11. A control system according to claim 9, wherein said circuit network is provided with a switching means to energize at least one of said four circuits responsive to the rotation of said main shaft by the operation of said foot treadle.