Patent GB-190911985-A (GB)
Title: Improvements relating to Elastic Fluid Turbines.
Inventor: BAILEY JAMES NICOLSON
IPC: F01D1/30
Filed: 1908-06-03
Granted: 1909-06-09
Abstract: 11,985. Hailey, J. N. June 3, 1908. Regulating.- In a controlling-device for a steam turbine, a valve device is adapted to cut off automatically the supply of steam to the turbine proper when the controller handle is moved from a power position to a lower power position, or to a reverse position, and to admit steam to a braking section of the turbine, the interval of time during which steam is admitted to the braking section being dependent on the extent of movement of the controller handle. The invention is described as applied to the system of marine propulsion described in Specification 12,075/08 in which an alternator driven by a turbine supplies currents of variable frequencies to an induction motor driving the propeller, the frequency being varied by a controller, which governs the supply of steam to the turbine by means of valves operated by pilot motors and electro-magnets. The induction motor 4 on the propeller shaft is supplied with current from the alternator 2 through the controlling-switch 13 and the reversing-switch 6. The alternator 2 is driven by a turbine 1 controlled by varying the position of the valve 24 by means of the pilot motor 20 acting through worm gearing 21. The reversing - switch 6 is connected by a link 14 to the controlling-switch 13, so that both move together. The face-plate 16 of the controller is mounted on the pivot 15, and may be rotated by the pilot motor 18 through worm gearing 17. The pilot motors 18, 20 are supplied from three-phase mains 88 at constant potential, and are arranged to run synchronously so that the position of the plate 16 corresponds to the position of the valve 24. To ensure synchronous movement, each rotor shaft carries make-and-break contacts 85 in the circuits of the electro-magnets 30, 31. These latter operate pawls 36 to rotate worms 79, 80, and, as long as the worms rotate at equal speeds, the wheel 29 simply rotates. When the worms rotate at different speeds, the wheel 29 rises or falls and moves the arm 26 over the studs 27 to vary the resistance in the rotor circuit of the motor 18. A. pipe 41 admits steam to the turbine steam-chest 40, and the valve 24 permits steam to pass through the pipe 42 to drive the engine. Another valve 45, normally closed, is in connexion with a pipe 43, which leads to a separate compartment with blades, or nozzles arranged for braking. The valve 45 is opened, and the valve 44 is closed to stop the supply of steam to the pipe 42, when the solenoid 48 is energized. The circuit of the solenoid 48 is completed by a switch 86 operated by the controller 13 through the link 14. When the controller is moved from the ' off ' position a a to the full ' on ' position a b, a circuit is closed from the battery or direct-current bus-bars 39, thorugh a solenoid 56, contacts 50, and lead 54. The solenoid 56 moves the arm 81 to engage the contacts 66. This completes the circuits of the pilot motors 20, 18, and the former commences to open the valve 24, and the latter to rotate the controller contact-plate 16. This continues until the plate 16 has moved sufficiently to break the contact between the arm 13 and the contact piece 50. If the handle is moved to reduce the speed, a circuit is closed from the battery 39 through lead 54, arm 13, contact 51, lead 75, and solenoid 57, back to the battery. The arm 81 is then thrown on to the contacts 67 to reverse the connexions of the pilot motors. Another circuit is closed from the battery 39 through lead 54, arm 13, contact 53, lead 82, contact 59, arm 77 of the switch 86, lead 63, and solenoid 48 back to the battery. The solenoid 48 closes the valve 44 and opens the braking valve 45. The pilot motors operate the valve 24 and contact-plate 16 until contact is broken between the arm and the contacts 51, 53, whereupon the solenoids 48, 57 are de-energized and the turbine is operated by a reduced steam supply. When the controller is moved to the ' off ' position, steam is not admitted to the braking section of the turbine, as the circuit of the solenoid 48 is broken by the switch 86. When the controller is moved from a low-power position to a reverse position, the solenoid 48 is energized and the braking valve 45 opened. In order to prevent the operation of the reversing-switch 6 when the alternator voltage is above a predetermined value, a stop 70 is attached to the core of a solenoid 71 across one phase of the supply wires.