| 摘要 |
<p>942, 742. Fluid pressure servomotor control systems. CHELTENHAM AUTO CONTROLS Ltd. March 24, 1960 [April 1, 1959], No. 11134/59. Heading G3P. [Also in Division B1] The supply of compressed air through a line 14 Fig. 1 and a throttle valve 15 to an intermittentblast producing means 12 for severe flow cleaning of gas filter bags 3 is controlled by unseating a normally closed valve 54 Fig. 3 between a compressed air supply line 24 and a chamber 57 open to line 14; said valve 54 being controlled by means responsive to the difference between the pressure drop across the filter and an adjustable reference pressure. Opposite sides of the filter bags 3 are connected by lines 19, 20 to opposite sides of the movable end wall 39 of a bellows 40 to which is secured a spindle 38 carrying diaphragms 25-28, 30 spaced by sleeves 41. The upper end of spindle 38 when displaced upwardly serves to throttle an adjustable nozzle 34 connected by a line 35 Fig. 2, a chamber 48 and a restrictor 49 to the inlet connection 50 of the compressed air supply line 24. The diaphragms 27, 30 carried by the lower end of spindle 38 forms the chamber 47 which is connected through a line 23 to the reference pressure unit 22. Diaphragms 26, 27, 30 form vented chambers 32 and diaphragms 26, 28, 30 form spindle control chambers 66, 68. In operation and when spindle 38 is urged upwardly by the pressure drop against the action of the reference pressure in chamber 47,the spindle obstructs nozzle 34 to cause a pressure build-up in chamber 48 which in turn depresses diaphragm 29 to open a normally closed booster valve 54 to allow access of compressed air from line 24 into a chamber 57 and thence through a union 58 into the line 14 leading to the blast producing means 12 which is constructed as described in Specification 922,281. Air pressure from chamber 57 also passes to spindle control chambers 66, 68 the diaphragms 30 of which being of greater area than diaphragm 28 tend to displace the spindle in opposite directions thus exerting a stabilizing effect. When a filter cleaning period the pressure drop falls sufficiently to allow the bellows plate to assume its normal retracted position, pressure in line 35 falls to a value at which valve 54 becomes seated and the air supply to line 14 is cut off.</p> |
