Patent GB-282505-A (GB)
Title: Improvements in apparatus for the automatic operation of plant or machines
IPC: C10J3/24
Filed: 1926-09-27
Abstract: 282,505. Power-Gas Corporation, Ltd., and Rambush, N. E. Sept 27, 1926. Water' gas plant.-In apparatus for the sequential operation of water gas plant, the elements, which may be remote from one another or from the control gear, are actuated bv servomotors controlled by a series of cams set in predetermined relationship, the periodical coupling of the camshaft to a main driving-shaft being governed by spaced operating-pegs on a continuously-driven drum or disc. The servomotor gear may be hydraulic or, where the controlled elements are adjacent to one another and to the control gear, may comprise a series of cam-actuated clutches for periodically connecting a number of driven shafts to a power shaft. The servomotor control gear may be thrown out of action manually or by automatic electric means, including limit switches and a time-lag switch, if any element fails to complete its movement in a piedeterminer interval. The steam, change-over, primary air, stack, tertiary air, and secondary air valves (not shown) are respectively controlled hydraulically by pilot valves 1 - - 6, Fig. 1, which are actuated in proper sequence by shrouded cams 24 - - 29 on a shaft 20 intermittently driven from the shaft 9 of an electromotor &c. 7 by gearing and one'-revolution clutch mechanism 16. Each revolution of the clutch shaft 18 causes 1 - of a revolution of the camshaft 20, n being 2n the number of cams, and so effects opening or shutting of a pilot valve. The motor shaft 8 drives, through change-speed gearing 12, the shaft 13 of a control disc 14 having adjustably mounted on its periphery pegs 15, Fig. 8, which actuate the trigger 60 of the clutch mechanism 16. There may be blank spaces X, Y, in which no peg 15 can be inserted, in order to ensure sufficient. time for the operation of certain main valves, and auxiliary pegs with broad faces may be provided to allow two or more successive rotations of the shaft 18, where valves are to be actuated in rapid sequence. The clutch mechanism 16, Fig. 9, comprises claw-members 70 held out of engagement against a spring 69 by contact of a cam 72 with a pin 73 on an arm. 63, which is keved to a shaft 61. The arm 63 and an arm 62, loose on the shaft 61, are pulled by springs 71, 74, and when the shaft 61 is oscillated by contact of a peg 15 with the trigger 60, the arm 63 and pin 73 are lifted. Simultaneously, a pin 64 lifts the arm 62, so freeing a stop thereon from the snail-cam 67 on the driven clutch part and allowing rotation of the shaft 18, the peg 15 normally releasing the trigger 60 before the end of the revolution. To ensure a complete revclution, a spring may be tensioned by a cam (not shown) on the shaft 18 during the first half-revolution, and react on the cam during the second half. Certain pilot valves may be hydraulically interconnected to ensure actuation of the main valves in the desired order. For example, the primary air valve is supplied with pressure fluid from the pilot valve 3 through a pipe 75, having a branch 79 to feed pressure fluid to the. secondary air pilot valve 6, which is thus only effective when valve 3 is open. Pilot valves 6 and 5 are similarly interconnected. With the pilot valve connections shown, the primary air, stack, and change-over valves would be operated by doubleacting hydraulic cylinders and the remainder by single-acting cylinders; this arrangement may be varied. The connection 91 to the steam valve cylinder communicates with pilot valve 1 through a pipe 94 and an additional pilot valve 89, normally held open by a weight 90 ; 143, 144 are the main pressure and exhaust connections respectively. Pilot valves 4, 3, 89 are provided with emergency actuating-cylinders 107 - - 109 fed from a pipe 106, normally connected to exhaust through valve 102, pipe 105, valve 103, and pipe 110. When, due to failure of a valve to function, the circuit of a solenoid 95 is broken, a weight 96 actuates a reversing-valve 97, so connecting a pressure-pipe 99 to exhaust and an exhaust-pipe 98 to pressure. A piston 100 in a cylinder 34 is then moved to the right, sliding the shaft 20 to disconnect cams 24 - - 29 from their tappet-rods, and displacing valve 103 by a yoke 101, without disturbing valve 102. Pressure is now fed through pipe 98, branch 104, valve 103, and pipe 105 to pipe 106 and the emergency cylinders 107 - - 109, whereby the corresponding pilot valves are actuated through links 148, 146, 147 to shut the primary air and steam valves and open the stack valve. If, by a hand-lever 35, the valve 102 be moved to the right, the emergency cylinders are exhausted through pipe 110, and the pilot valves 1 - - 6 may be actuated by handlevers 37, 38, 38A - - D, Figs. 1 and 14, which are rigid with pinions 41 - - 43, 43A. - - C on shafts 50, 51, 51A, 51B. These pinions engage racks 44 - - 46, 46A - - C, which are connected to the valve spindles and engage also pinions 47 - - 49, 49A- - - C, mounted on shafts 39, 40 and provided with balanced-weights 145. The shafts rigidly carry locking-discs 52 - - 54, 54A - - C, 55, 55A - - C with coacting segmental cut-away portions, and some of the pinions are loose on their shafts, the arrangement being such that certain valves cannot be hand-operated unless certain other valves are in either open or shut condition. On resetting the reversing-valve 97 by a lever 111, piston 100 restores both valves 102, 103. The lever 35 may be used to disconnect the cams manually. Fig. 13 shows the electrical connections. The motor 7, having an electric brake 114, is connected to three-phase supply 112 through a starting-contractor 115, the solenoid of which is controlled by a switch 116 adapted to be opened on deenergization of a solenoid 117 in the directcurrent leads 118, 119. The. direct-current, circuit includes a motor-starting switch 121, main switch 120, overload relay 129, " no-volts " relay 130, a series of reversing-switches 122 - - 124, ... actuated by the pilot valves, and pairs of limit-switches 125 - - 128 - -, actuated by the main valves. If the circuit 118, 119 be broken anywhere except at switch 121, the solenoid 95 of the reversing-valve 97 is deenergized by opening of switch 134, and also the driving-motor 7 is ultimately stopped. The movement of any pilot, valve, by throwing over its reversing-switch, breaks the circuit in lead 119 until the corresponding main valve has reached and closed the appropriate limit-switch; the circuit is, however, normally maintained through a parallel lead 119<1> for, say, five, seconds by a time-lag switch 135, which is closed by the link 136, Fig. 8, simultaneously with tripping of the clutch 16. If a valve fails to complete its travel in the prescribed time. the plant is shut down in a safe condition, an alarm-bell 139 rung, and, if desired, a signal-lamp lighted to indicate the fault. When a notch 142 in a disc 141, Figs. 1, 8, and 13, adjustably secured to the timing- disc 14, is aligned with a pin 140, switch 116 is opened to stop the motor 7 and leave the disc 14 in the " zero position of its cycle. The pegs 15 may be carried on a chain running over sprockets or on any rotary element.