Patent GB-748164-A (GB)
Title: Improvements in or relating to the control of sequentially operated multi-unit apparatus such as dust recovery plant
IPC: G05G21/00
Filed: 1953-12-03
Abstract: 748,164. Air filters. JORDAN, K., and VIERIG, R. Dec. 3, 1953 [Dec. 4, 1952], No. 33555/53. Class 8(2). [Also in Group XXIX] Apparatus for sequential control of a plurality of gravity-biased flap valves 17, Fig. 2, of a multi-compartment air filter comprises a control cam 11 for each valve 17 so mounted on a common shaft 5 as to allow relative angular movement thereto, e.g. 30 degrees, the control cam 11 being moved to the valve opening position by turning the shaft 5 30 degrees and abutment of a dog 15a secured to the shaft against a dog 15 being turned to the valve closing position by means independent of rotation of shaft 5 e.g., a cam 9 on a continuously rotating shaft 4 geared to a drive shaft 1 abutting a roller 13 of the cam 11. Each filter compartment is also provided with a valve 18, Fig. 3, for admission of purging air when valve 17 is closed and is controlled in a similar manner to valve 17 by a cam 12, a dog 16 thereof, a dog 16a of shaft 5, a roller 14 and a cam 10 on shaft 4. The 30 degree forward steps of shaft 5 is effected by a twelve-toothed ratchet 7, Fig. 1, secured thereto being engaged by a pawl 8 of shaft 4 the period of which equals the cleaning period of each compartment e.g., 20 seconds. As shown valve 17 is about to be closed by a 30 degree step of cam 11 effected by cam 9 abutting roller 13. Almost immediately afterwards the cam-actuated pawl 8 moves ratchet 7 and shaft 5 forward 30 degrees resulting in dog 15a catching up with cam dog 15 and also in actuation of cam 12 by abutment of dog 16a of moving shaft 5 against dog 16. At the end of the purging period of the compartment concerned the valve 18 is closed by cam 12 being moved forward 30 degrees relative to the shaft 5 by cam 10 abutting roller 14, and valve 17 is closed when cam 6 and pawl 8 stops ratchet 7 and hence shaft 5 a further 30 degrees resulting in forward angular displacement of valveactuating cam 11. In modification a ratchet 23, Fig. 4, corresponding to ratchet 7 has teeth 24, 25 of varying angular pitch, and shaft 4 carries cams 27, 28 of varying lift and adapted to actuate a common pawl system whereby the shaft 5 may be advanced in steps of varying magnitude thereby accommodating a plant with a fewer number of compartments having the same individual purging times as for twelve compartments. In a further modification the common cam shaft 5 comprises two aligned portions 30, 31, Fig. 7, each controlling sequentially the changeover valves of the compartments of a group of compartments. Each shaft 30, 31 is advanced in turn independently of the other to an extent limited by the number of teeth on ratchets 32, 33 secured to shafts 30, 31 respectively and driven from the continuously rotating shaft 4 through a cam 29 and a unitary pawl 39, 40. Each ratchet 32, 33 has one tooth missing and in the position shown in Fig. 6 pawl 39 is riding idle on the stationary ratchet 32 whilst pawl 40 advances ratchet 33 and hence shaft 31 and the valve-actuating cams (not shown) secured thereto. Coincident with pawl 40 engaging the tooth prior to the gap in ratchet 33, a dog 35 thereof engages a dog 34 of ratchet 32 and advances the latter so that pawl 39 re-engages the teeth thereof. At this time pawl 40 rides idly in the gap of ratchet 33 which with shaft 31 remains stationary until advanced forward by dog 34 of ratchet 32.