GB918477A - Improvements in pneumatic feeders - Google Patents

Abstract

918,477. Pneumatic conveyers. VOKES Ltd. Sept. 22, 1961, No. 34033/61. Class 78 (1). In a pneumatic feed system for loose materials such as tobacco in which the material is mechanically fed to feeder 1, Fig. 1, for controlled pneumatic delivery to any one of a number of dischargers 4, 4<SP>1</SP> according to demand of utilizing machines, the system is adapted to stop the mechanical feed in the event of a blockage in the manifold delivery pipe 2 as signalled by a detector 15 and to apply suction in succession to each of the dischargers 4, 4<SP>1</SP> so that pulses of suction are applied to the system to assist in clearing the blockage. In one example a timer motor M, Fig. 2, successively closes multiple searching switches C5, C5<SP>1</SP> or more associated with multiple dischargers 4, 4<SP>1</SP> and in the event of a tobacco utilizing machine at a discharger signalling a demand, completes a circuit through a solenoid L12 or L12<SP>1</SP> controlling the opening of a valve 7, or 7<SP>1</SP> in the suction line to that discharger. Application of suction closes one of the discharger doors 9, 9<SP>1</SP> to induce suction in the delivery lines 3 or 3<SP>1</SP> and completes a signalling circuit by closing contacts 10, 11 or 10<SP>1</SP>, 11<SP>1</SP> operating solenoid relays L3 or L3<SP>1</SP> to close contacts C3 or C3<SP>1</SP>. If the manifold line 2 is clear, contacts C15 controlled by the detecting device 15 remain closed and a circuit is completed through a feeder starter relay solenoid L1 which starts the mechanical feed to the feeder 1 through contacts (not shown). On discharge into the machine the contacts 10, 11 or 10<SP>1</SP>, 11<SP>1</SP> open to place the solenoids L3 or L3<SP>1</SP> into open circuit, opening contacts C3 or C3<SP>1</SP> to stop the mechanical feed. Release of the feeder starter relay solenoid L1 closes contacts C1 completing a circuit through a time delay relay T, L2 which opens normally closed contacts C2 in the circuit of the solenoid L12 after a given time sufficient for the valves 7 or 7<SP>1</SP> to remain open until all material has been cleared from the delivery pipelines 3 or 3<SP>1</SP>. Release of the solenoid L12 closes contacts 12 for retarting the cam motor M. In the event of a blockage in the manifold 2 the contacts C15 remain open so that the circuit through the solenoid relay L1 cannot be completed and mechanical feed to the feeder 1 is prevented under all conditions. The time delay relay T, L2 is therefore always placed in circuit by closure of the contacts 10, 11 or 101, 11<SP>1</SP> on the discharger doors 9 or 9<SP>1</SP> due to the contacts C1 remaining permanently closed. The solenoids L12, L12<SP>1</SP> are therefore operated alternately at the set time interval to apply suction to the dischargers sequentially until the blockage has been cleared. In a modification (Fig. 3, not shown) additional contacts and holding relays are incorporated to maintain suction at one of the dischargers while the remainder of the dischargers are subjected to suction in pulses according to Fig. 2.