Patent GB-450141-A (GB)
Title: Improvements relating to the remote control of dynamo electric generators
IPC: B23K9/10
Filed: 1934-11-09
Abstract: 450,141. Control systems for welding arcs; distant -control systems; motors; electromagnetic switches. LINCOLN ELECTRIC CO., 12818, Coit Road, Cleveland, Ohio, U.S.A. Nov. 9, 1934, No. 32340. Convention date, Dec. 4, 1933. [Classes 35 and 38 (iv)] [See also Groups XXXVII and XXXVIII] The output, or other characteristic of a generator supplying an arc welding circuit is controlled in response to intermittent closure of an external circuit of the generator, control being effected on the generator series or shunt field or the means driving the generator. A relay 64 in series in the welding circuit in response to intermittent closure of that circuit, controls the operation of an electromagnetic selector switch 17 which puts one of two electromagnets 15, 16 controlling a generator field rheostat 13, into circuit in series with the relay 64 so that, thereafter, further impulses cause variation of the resistance 13 in the selected direction in steps. Five short successive closures of the welding circuit produce five limited oscillations of the armature 31 of the selector switch 17 each oscillation producing a rise of one step in a spindle 40 through the medium of a pawl 36 oscillated with the armature 31 and a ratchet 41 on the spindle 40. A spring urged detent 43, 45 holds the spindle at each step and is released by a pin 24 on an inertia disc 22 which is rotated by the opposing forces of a fixed spring 27 and a spring 33 tensioned by a member 32 on the armature 31. During the five short oscillations of the armature the pin 24 is moved sufficiently to the right in Fig. 2 to allow operation of the detent but not far enough to separate a pivoted contact lever 48, connected to it by means of a spring 50, from a counter contact 46. When the spindle 40 has been raised by five steps a plunger 53 thereon closes two contacts 52, 51 and connects the coil 15 of the rheostat controller through contacts 48, 46, and 51, 52 of the selector 17 and contacts 64 of the series relay to the terminals of the generator exciter 12. Thereafter on continued intermittent closure of the welding circuit causes, at each closure, a movement of the arm 14 of the rheostat 13 in the counter clockwise direction to increase the generator output progressively. If it is desired to decrease the generator output the welding circuit is first closed for a predetermined time thereby causing the inertia disc 22 of the relay 17 to rotate clockwise until the pin 24 moves over to the right of a guide slot 23 in a stationary bracket 19. This causes the arm 48 to snap over to the contact 47 thus preparing the circuit of the electromagnet 16 on the rheostat controller. Five short closures of the welding circuit are now made, thereby lifting the spindle 40 until the contacts 51, 52 are closed, and thereafter all further impulses produce, at each energization of the coil 16, an increase in the generator field resistance 13. The field rheostat control comprises two solenoids 15, 16, Fig. 5, the armatures 57, 58 of which are connected together by means of a cord passing over a pulley 54 which is mounted on the shaft of the rheostat arm 14. The armatures are connected by brackets 61 with the solenoid structure through the medium of tension springs 60 and compression springs 59 so that the cores are in equilibrium in any position. The selector 17 may comprise a casing 65, Fig. 4, in which a coil 28<a> is mounted and through which a vertically movable spindle 66 passes, the spindle being provided with a weight 67 and a dashpot 69. Loosely mounted on the spindle is the armature 75 which co-operates with a sleeve 79 within it so as to clutch it to the armature and the spindle 66 only during upward movement of the armature. Depending studs 70 from the casing carry a link 74 through which passes the spindle 66 and studs 76, 77 depending from the armature. A. stop 73 on one of the studs 70 limits the movement of one end of the link 74 and a stop 78 on one of the studs 76 causes lifting of the link when the armature rises. Projections 80 from the sleeve 79 bear on the plate 74 so that when the coil 28a is energized the armature 75 rises and takes with it the sleeve 79, spindle 66 and link 74 until the link 74 contacts with the stop 73, when further rise of the armature causes lifting of the sleeve 79 relatively thereto and releases the spindle 66. Return of the spindle is delayed by the dashpot 69, so that intermittent energization of the coil 28a causes the spindle 66 to rise in steps and carry with it a collar 90. The collar 90 is connected by springs to pivoted contact arms 88, 89 which co-operate with contacts 85, 86 and 87 connected in the circuits of the rheostat operating coils 15<a>, 16<a> so that at the end of five successive energizations of the coil 28<a> the lever 89 moves over to the contact 87 whilst contacts 88, 86 still remain closed. Further impulses at the correct rate produce impulse energization of the coil 15<a> to produce the desired control of generator output. If the coil 28<a> is energized more than five times rapidly, the arm 88 is moved over to the contact 85, and thereafter further impulses produce operation of the coil 16<a> to effect control in the reverse sense. The selector switches &c. may be controlled from a separate circuit of the generator, contacts for this control being provided on or near the welding electrode holder. The control may be effective on the speed of the generator as by control of the speed of an I.C. engine driving the generator e.g. throttle control, or rheostat control of the speed of a motor driving the generator. The control may also de-energize or stop the driving means for the generator. The rheostat control may be on the generator shunt or series fields or both. The Specification as open to inspection under Sect. 91 disclosed an arrangement in which the selector relays may be dispensed with, and two switches for the direct impulse control of the coils 15 or 16 of the rheostat switch may be provided on the electrode holder. Moreover, if control is required in one sense only, a single impulse coil on the generator field rheostat may be provided, the circuit of which is controlled by a switch operated by a dashpot controlled armature the coil of which is connected across the main generator terminals. Successive closure of the welding circuit reduces the generator voltage at each closure, and de-energizes the coil sufficiently to allow the armature to drop against the action of the dashpot so as to close the circuit of the rheostat magnet coil. Further impulses produce step control of the rheostat. This subject-matter does not appear in the Specification as accepted.