Patent GB-784730-A (GB)
Title: Controlling means for rotary machines
IPC: B04B9/06
Filed: 1955-09-02
Abstract: 784,730. Centrifugal separators. CIBA Ltd. Sept. 2, 1955 [Sept. 3, 1954; Aug. 24, 1955], No. 25322/55. Class 23 [Also in Groups XXIV, XXV and XXVI]  In a centrifuge having a part or cover located in a first or closed position during rotation of the shaft of the centrifuge and in a second or open position when the shaft is stationary, a fluid pressure system is provided for moving the part to the second position and for controlling move ment to the first position, means operated by a mechanical connection with the shaft prevent the fluid pressure acting to move the part whilst the shaft is rotating, and means operated by the fluid pressure used to move the part to the second position and by fluid pressure produced by the movement of the part to the first position cut off supply of power to the shaft. The centrifuge 10 is driven by a Pelton wheel 18 having valve controlled nozzles 19, 21 for driving and braking respectively. A gear pump 27 mounted on the centrifuge shaft circulates oil the pressure of which is indicated on a gauge 30 calibrated to register the speed of the shaft. Linked valves 31, 32 are set in the position shown so that air from a line 40 is supplied to a cylinder 22 to open the nozzle 19 to drive the centrifuge. The oil pressure generated by the pump during rotation of the centrifuge keeps a valve 39 open so that a valve 35 is closed and air from the line 40 is not supplied through a line 43 to the top of a cylinder 15 housing a piston 16 linked to the cover 11. The centrifuge is stopped by turning valves 31, 32 clockwise through 90 degrees so that the nozzle 19 closes and air is supplied to a cylinder 23 to open the braking nozzle 21. When the centrifuge stops the oil pressure falls, the valve 39 closes, the valve 35 opens, and air from line 40 passes to line 43 to open the cover. The pressure of air in the line 43 causes a valve 33 to be actuated to shut off the supply of braking fluid to the turbine. When the valves 31, 32 are returned to the starting position, the cover falls under its own weight, the rate of fall being controlled by the discharge of air entrapped above the piston and it is not until all this air is discharged that valve 33 is reset so that the drive nozzle is opened. In the modification shown in Fig. 2 the centrifuge is driven by a three phase motor which is started by closing a switch 54 in a 220 volt circuit to close a solenoid operated switch 61. A switch 52 connected to the centrifugal shaft is closed during rotation of the centrifuge and causes a solenoid operated valve 51 to vent the line 43 to atmosphere so that air pressure from the line 40 is not applied above the piston 16 to open the cover. With the valve 32 set in the position shown, air from the line 40 passes through a valve 50 to the underside of the piston to keep the cover closed. The centrifuge is stopped by rotating the valve 32 anticlockwise through 90 degrees and by opening the switch 54. When the centrifuge ceases to rotate the switch 52 is opened and the valve 51 connects the line 40 to the line 43 to open the cover, pressure in the line 43 opening a switch 53 to make the 220 volt supply so that the motor cannot be started.