GB909345A - Improvements in or relating to air filters - Google Patents

Abstract

909,345. Air filters. SIMON Ltd., HENRY. May 1, 1961 [May 18, 1960], No. 17503/60. Class 8(2). Reverse flow cleaning of a plurality of inward flow filter sleeves e, Fig. 1, having their upper open ends supported by an apertured horizontal plate 14 which divides the filter casing into a lower dust-laden air chamber c and a filtered air chamber a having an outlet b is effected by compressed air pulses issuing through apertures in the sides of vertical tubes g projecting down each filter sleeve and connected to a header f mounted on a carriage 20 which is movable step-wise along tracks 15 in order to traverse the filter sleeves, an air pulse being supplied to the tubes g at the end of a movement step from a reservoir h and a cut-off valve k. The carriage 20 is driven between the extremities of the open ends of the filter sleeves by a chain 22, Fig. 4, passing round a pair of sprockets 23 one of which idles whilst the other is driven by a shaft 25 secured to a pair of rachet clutches 27 linked to the piston rods of spring-returned compressed air operated jacks 29 connected through a two-way selector valve 37 and a pressure-opening valve 35 to the reservoir h. In operation and assuming the reservoir from a supply line 31 through a valve 32, which is responsive to a predetermined pressure difference between chambers a and c, compressed air passes through valve 35 and valve 37 to one or other of the jacks 29 to extend the same and thus move the carriage 20 and tubes g a short distance along the sides of the filter sleeves. At the end of the stroke a jack cam 40 opens a pilot valve 41 to connect the operating member of the valve k to the line 31 resulting in a pulse of compresesd air being passed from the reservoir during its discharge through valve k to the tubes g. The jack is then retracted by its return spring, the associated pilot valve 41 and also valve k are closed and when control valve 32 is reopened by an increase in said pressure differential the reservoir becomes recharged and the cycle is repeated at intervals until the carriage reaches one end of its run. At this stage the carriage opens a valve 26 to allowaccess of compressed air from line 31 through a valve 34 (which is open only when the reservoir pressure is low) to the operating member of two-way valve 37 to switch it to its other position in which it controls the other jack for effecting the return run of the carriage 20. In a modification the several filter elements are arranged coaxially and the air duct revolves in steps about their axis. Specifications 768,634 and 887,309 are referred to.