GB811462A - Continuous feeder - Google Patents

Abstract

811,462. Fluid-pressure servomotor control systems. B.-I.-F. INDUSTRIES Inc. May 7, 1956, No. 14058/56. Class 135. [Also in Group XXXVIII] Apparatus for weighing fluid material continuously comprises two hoppers which are filled alternately, the rate at which the one hopper is being filled controlling the rate at which the other hopper is being emptied, the change-over occurring when the weight of the filling hopper reaches a predetermined value. Electrical embodiments.- Two upper hoppers 10, 14 (Fig. 1) are continuously filled with material which is allowed to fall alternately into two lower hoppers 12, 16, each hopper having a rotary valve 18, 20, 22, 24 controlled by an electric motor 26, 28, 30, 32 respectively the arrangement being such that when lower hopper 12 is being emptied the outlet from its upper hopper 10 is closed, while upper hopper 14 is feeding into lower hopper 16 which is itself cut off. Each of the lower hoppers 12, 16 is supported about a fulcrum 50, 52 and is balanced against a counterpoise weight 58, 60 movable along scale beams 46, 48 in opposite directions by a motor 76 through a reversible clutch 72. At the start of a cycle, after operation of limit switch 118, motor 76 drives the counterpoises to produce unbalance of the beams 46, 48 whereby switch 124 is closed intermittently to energize motor 28 and valve 20, and switch 126 is closed intermittently to energize motor 30 and valve 22, thereby maintaining the rate of emptying hopper 12 at the same rate as the filling of hopper 16. When counterpoise 58 reaches limit switch 116, clutch 72 reverses the direction of rotation of shaft 70 and the apparatus continues to operate with hopper 16 emptying and hopper 12 filling. A counter 185 indicates the total weight of material flowing through the hoppers by counting the revolutions of shaft 70. In a modification (Fig. 2, not shown), the control switches 124, 126 are replaced by fluid pressure switches. In a further embodiment (Fig. 3) the weight of the hoppers 412, 416 is determined by strain gauges 442, 444 which form one arm of bridges 500, 502 whose unbalance currents control the rates of filling and emptying the hoppers. Pneumatic embodiment.-The weights of the hoppers 612, 616 (Fig. 4) are sensed by pneumatic transducers 704, 706 which control the rates of filling and emptying via control units 641, 643 acting on diaphragms 629, 631 controlling gates 620, 622. Change-over is effected by limit switches 716, 718 reversing the operation when the filled hopper reaches a predetermined weight.