Patent GB-849207-A (GB)
Title: Improvements in or relating to wash box control devices
IPC: B03B5/24
Filed: 1958-07-08
Abstract: 849,207. Jigs. LINK-BELT CO. July 8, 1958, No. 21875/58. Class 82(2) [Also in Group XXIX] A control device for automatically regulating the rate of discharge of the heavy particles in an air pulsated type of wash box 21 in response to the variation in the air pressure in the space above the wash liquid comprises a driven rotary discharge gate 26, a pressure measuring device 61 which is connected to and responsive to the pressure variations in the air space, and a control unit 58 which is actuated by the pressure device 61 to regulate a fluid motor 48 which varies through a continuous range the rate at which the drive rotates the discharge gate in order to maintain the hydraulic resistance of the material bed B constant. Compressed air to force the wash water through the bed is supplied to box 21 through inlet valves 32 operated simultaneously by cam shaft 34. Pressure variations in the air space which vary according to the thickness of bed B are transmitted via a solenoid operated valve 63 and tube 62 to the pressure measuring device 61, the valve 63 being actuated in timed relationship with the inlet valves 32 by a limit switch 65 so that the pressure measuring device 61 is connected to the air space only during like portions of successive air pulsations. The pressure variations change the position of a calibration slider 193 and pointer 195 of the differential linkage 176. A pivotally mounted flapper valve and lifting arm in a control unit 106 is connected to this linkage by a control link 175 and any variation in pressure changes the position of this flapper valve in relation to a tube 146 and regulates the rate of dishcarge of the regulated air pressure from pilot relay 105. Pressure regulated air is supplied to the pilot relay 105 by pressure regulator 53 via tube 104 and as the rate of air discharge from tube 146 varies, an inner and outer bellows and a flapper valve in pilot relay 105 adjusts the control air pressure supplied to tube 109 and is registered on gauge 108. This controlled air pressure is also fed back to control unit 106 which contains a spring loaded bellows and cam arrangement for setting the position of the flapper lifting arm. For a given setting of this cam the control air pressure in unit 106 will vary in direct proportion to the pressure variations applied to device 61. The controlling air pressure from tube 109 is supplied through a transfer switch 96 to an actuation controller 55 which regulates the fluid motor 48 to adjust the rate of discharge of the gate 26 to maintain the depth of the bed B at the desired level. The transfer switch 96 allows automatic or manual control of the control air pressure supplied to the actuation controller 55. During manual operation the pressure regulator 97 is manually regulated to maintain the pressure reading of gauge 98 equal to the proper control pressure indicated on gauge 108. In the actuation controller 55 which is also supplied with regulated air pressure from pressure regulator 53, any variation in the control air pressure from tube 57 operates an adjustable spring loaded bellows and pilot valve which results in a movement of a spring balanced diaphragm in the fluid motor 48 and the movement of an operating plunger 49. An operating rod 47 connected to plunger 49 by lever 50 moves a cover plate 43 to positions overlying a varying number of teeth on a ratchet wheel 42 in the path of movement of a pawl 41 which is connected to a motorized speed reducer 36 by a radial arm 39 and connecting rod 38. The speed reducer is operated continuously and the position of the cover plate 43 regulates the amount of intermittent rotary motion of the discharge gate 26. To maintain the thickness of the heavy particles in the bed B at a given value, the index arm 184 is positioned at a set point corresponding to the desired pressure, pointer 195 is aligned with this and the flapper valve will then cause the pressure in tube 146 to maintain the control air pressure at the desired value for the required rotation of discharge gate 26