Patent GB-190518209-A (GB)
Title: Improvements in Electric Control Systems and Apparatus therefor.
Inventor: LEONARD ALEXANDER TIRRILL
Filed: 1905-09-08
Abstract: 18,209. Tirrill, L. A. Sept. 8, 1904, [date applied for under Patents Act, 1901]. Void. [Published under Patents Act, 1901.] Points and switches.-In controlling an electric motor used for operating railway switches or other apparatus, means are provided for producing a given movement from, and indicating it at, a distant control station, and for stopping the motor automatically when a predetermined point has been reached. The invention is described with reference to a valve of the sliding-gate type, closed by the longitudinal movement of a spindle 5, Figs. 1 and 20, which is screw-threaded on the upper part and passes through a nut 6, keyed to a spur-wheel 9, driven by a train of wheels from a series motor 15, and also by a hand-wheel 16. Current to the motor passes from mains 17, 18, Fig. 26, through a reversing-switch, shown diagrammatically at 26, 27, and consisting of four two-edged switch blades 26, Figs. 15 and 16, mounted parallel on a rocking shaft 28 between four corresponding pairs of clip contacts 20, 20<1>. The shaft 28 is normally held in the mid-position by springs 35, and is adapted to be rocked by bell-shaped armatures 29, 30 of electro-magnets 31, 32, hinged to the bottom of the enclosure 25. A blow-out magnet 37 in series with the motor field F has three polepieces 38 lying between the different pairs of contacts and mutually separated by plates of insulating- material 39. The distant controller comprises a box 45, Fig. 2, containing a rotatable switch arm 47, carrying an insulated spring contact 48 over studs 51 and a segment 49. The arm also carries a visible pointer 52, Fig. 1, and has a notch 61, Fig. 13, in its hub engaging with a latch 60, hinged to a lever 54, forming part of a notched sectorshaped piece 58 which is rigidly fixed to an outside operating-handle, the notched rim being pressed by the roller end of a spring lever 59, Fig. 2. A spring 62, Fig. 3, retracts the switch arm 47 when the latch 60 is raised, which takes place whenever an electro-magnet 63, in shunt with the mains 17, 18, Fig. 26, is,excited by closing one of the emergency switches 68. In certain cases, the con - struction may be so modified, that the switch arm, on being released from the detent, moves forwards. The controller is shown in the " off position, the valve being closed. When the handle 56 is turned, so that the contact 48 makes one step to the right, current passes to the second stud 51. All. the studs are made with spring buttons 75, Fig. 8, projecting below the carrying-plate and resting on. curvedcopper plates 78, 79, Fig. 26, fixed to a double centrally-pivoted sector 69. The plates are mutually insulated by an insulating-block 72 and narrow curved strips-of insulating-material, and are so shaped that, as the sector is moved, the spring projections 75 will pass successively out of contact with one and into contact with the other plate. In the initial position they lie as shown in Fig. 26, the extreme left-hand stud in connexion with the insulating-block 72 and the rest with the copper plate 79. The first movement of the controller handle to the right thus sends current by way of the strip 79 and the wire 120 through the first operating-magnet 31 of the reversing- switch, and also by way of the wire 121 to one of a pair of electro-magnets 91, 92, the function of which is to move the -sector step by step. The electro-magnets have bell-shaped armatures 93, 94, Figs. 4 and 11, hinged to an arm 83 pivoted at 46. A pin 88, Fig. 3, freely mounted in a bearing in the arm, is fixed at one end to a double pawl 82 and at the other end to a short upwardly-extending arm 87, the free end of which is held in the mid-position by spring stays 89. When the arm 83 is pulled aside by one of the electro-magnets, the far end of the pawl 82 is thus caused to dip into contact with ratchet teeth 81 on the internal rim of the sector 69, over which it slips in consequence of the yielding of the spring stays. On the return movement of the arm caused by the springs 84 when the magnet becomes de-energized, the ratchet is carried forwards one tooth. The electro-magnets 91, 92 are connected to the mains through an interrupter shown in Figs. 24, 25, and 26. A commutator cylinder 101, composed of four conducting and four equal insulating segments fixed to a worm-wheel 100 in gear with a worm 12, Fig. 20, and the end of the nut 6, and a second cylinder 104, divided into two conducting-surfaces 105, 106 by an insulating-band round the middle, and having also a straight insulating-strip running from end to end, are geared together by a Genevastop arrangement and are connected by metal springs 117, 118. A brush 113, in series with the copper segment 79. rests in the initial position of Fig. 26 on a conducting-part of the commutator 101. The cylinder 101 is caused to make two revolutions during one complete opening and closing movement of the valve.' The first impulse of current from the main through the second stud 51, the segment 79, and the wires 120, 121, traverses the magnet 91, the brush 113, the cross connector 117, the cylinder 105, and the exit brush 114 to the negative main. After the motor has moved so far that the valve is opened one-eighth, the commutator 101, being rotated a corresponding amount, interrupts the current in the line 121, -and the arm 83, Fig. 4, is brought back to mid-position by the springs 84, causing the sector 69 to turn one step in the same direction as the controller sector 58, which movement brings the insulating-block 72 under the second of the contact studs 51 and breaks the circuit of the magnet 31, the reversing-switch 26, 27 then opening and cutting out the motor. If the controller contact 48 is moved inthe first place to one of the farther studs; the' motor will continue to run in the same direction until the sector 69 has caught up the sector 58. A pointer 73, Figs. 2 and 8, carried by the sector 69, plays over the same scale with the pointer 52, opposite which it comes to rest, thus indicating that the motor has stopped and that a predetermined travel of the valve has been completed. A subsequent backward movement of the controller handle to the first of the studs 51 diverts current through the segment 78 and the wire 122 to the magnet 32, operating to connect the motor reversely. From the magnet 32 current traverses a brush 115 on the cylinder 105 and thence to the negative main. Through the wire 124 current is also led through the magnet 92 to a brush 116 on the cylinder 106, through the cross-connectors 117, 118 to the cylinder 105 and to the negative main. In the same manner as before, the indicator sector follows the backward movement of the controller sector until the pointers are in coincidence. If any one of the emergency switches 68 is closed, the controller arm 47 springs back to zero, and the valve necessarily closes. '