Patent GB-172357-A (GB)
Title: Improvements in electric stop motions for machines operating with yarns or threads
IPC: D03D51/00
Filed: 1920-07-30
Abstract: 172,357. Roberts, A. July 30, 1920. Yarns. warping.-An electric stop-motion for use in electrically-driven textile machines comprises means to cut off the current from and provide dynamic braking on the motor when a thread breaks or becomes slack. Fig. 7 shows a yarn switch in which a thread 76, passing between porcelain eyes 79, supports a pivoted feeler arm 80. On breakage of the thread the feeler arm drops, thus causing a contact to bridge the gap between the contacts 82, 83 and to establish a circuit which ultimately breaks the armature circuit of the driving motor. Fig. 1 shows diagrammatically the connections for direct-current supply apparatus. To start the machine, the control switch 24 is moved to connect contacts a, d, thus making a circuit including a solenoid 9, which operates contacts 6, 7, 8, 11, 13, 16. When contacts 6, 7, 8 touch their corresponding studs in sequence, the series winding 2 and the armature of the motor 1 are connected to the main switch 4 and are energized. When terminals 11, 12 make contact, the field shunt winding 3 assumes full strength and the motor starts, and as resistances 5 are gradually cut out the motor is brought up to normal speed. Finally, the coil 9 introduces a cooling-resistance into its own circuit, and by a special arrangement of the contact 12, the held-regulating resistance 29 is cut into the field circuit. When the lever of the switch 24 is released, it returns to the normal position connecting a to c and b to d, thus relaying the circuits of the yarn. The yarn circuits are tapped from a resistance 21, which is direct across the mains. If one of the yarns or threads break, its switch 28 is closed, completing the circuit to the operation coil of a relay 23. This separates contacts as shown in the circuit of the starting-coil 9 and allows the main contacts 6, 7, 8 to break contact with their studs, and by making contacts 13, 14 causes only a small armature current to flow through on account of the resistance 15. which gives the automatic braking effect. The field regulating resistance 29 now in circuit may be varied by hand to vary the degree of braking. The closure of the switch 28 also operates a selecting relay 25 to complete a circuit to the indicating lamp 27. Fig. 2 shows the connections for alternating current supply; in this arrangement a 3-phase motor 31 drives the machine. Current is supplied through a switch 32 to terminals A, B, C. Terminals D, E, are cross connected with A, B, to get reversal of current. A transformer 47 supplies low-voltage current to the yarn circuits and an electromagnetic switch 49 automatically reverses the current in the motor when a thread breaks, while a mechanically-operated switch 50 opens the circuit to the control switch should the loom tend to run in the reverse direction. To start the machine, contacts a-d, a<1>-d<1> are made on the control switch 46, thus completing the circuit to the solenoid 41 while the circuit to the yarn switches 28 is opened. The solenoid 41 pulls up contacts 35, 36 37, 43, the latter closing a circuit to a switch coil 45 which completes contacts A, B to contacts 33, 34 thereby starting the motor. Removal of the hand from control switch 46 opens the circuit to solenoid 41 so that the contacts 35, 36, 37 drop down in sequence on contacts 38, 39, 40 thereby cutting out resistance and bringing the motor up to speed. The contact 43 also drops away from contact 44 but the circuit through main switch coil 45 is maintained through union of the contacts 51, 52 formerly. When the control switch is moved to the stop position, the circuit to the main switch coil 45 is opened, the circuit to the reversing switch 49 is closed together with the circuit to starter solenoid 41. This cuts resistance into the motor circuit and reverses the current to two phases, thus quickly bringing the motor to a standstill. When a thread breaks, a relay switch 28 closes and energizes a coil 48 which duplicates the circuits made by the control switch 46 when in the stop position, and thus stops the motor. Lamps 28 indicate the individual broken yarns as formerly. The switch contacts 11, 12, Fig. 1 are shown detailed in Fig. 3, in which the contact finger 53 on the first part of its movement makes contact with contact 54 thus short circuiting the field regulator. Further movement of the finger 53 brings it into contact with an insulating block 55, thus cutting the field regulator into the circuit. Thus the motor has full field for starting and in stopping, the field regulator being in the field circuit and variable giving adjustable dynamic braking. Figs. 4 and 5 show a reverse direction switch for the alternating current drive in which a crowned pulley 56 freely revoluble on a spindle 58 runs on a loom circle. The spindle carries an insulating switch blade 59 engaging contacts 60. 61 and also carries a friction disc 65 and spring 66 to give the spindle a bias in the direction of rotation of the pulley 56. The pulley is flexibly held in contact with the loom circle bv a spring lever 68 as shown. In operation, if the loom circuit reverses, the contact blade 59 opens the circuit between the contact 60, 61 and stops the motor. Fig. 6 shows the arrangement applied to the bearded needle knitting machine in which the motor drives, through gearing, the loom circle 57. The yarn is brought from a bobbin 77 to the feeler and yarn switches 28 as previously described.