Differential pressure-responsive device

摘要

1,141,278. Valves. KINGMANN-WHITE Inc. 8 Jan., 1968 [18 Jan., 1967], No. 1021/68. Heading F2V. [Also in Division G1] In a fluid pressure responsive device differential pressures are applied to the device through bores 140, 142, assuming the higher fluid pressure is applied to bore 140, the pressure is communicated through a duct 144, an annular passage 172 between a damping snubber bore 164 and a piston 170 into a base cavity 24 and through a normally open pressure inlet controlled valve 125 into the inner portion of a bellows 56. The lower fluid pressure is applied through the bore 142, duct 150, an annular passage 172 between a damping snubber bore 164 and a piston 170, a duct 154 into an outer chamber 86 within a cover 16 externally of the bellows 56. The pressure difference internally and externally of the bellows 56 causes, if the internal bellows pressure is higher, the bellows 56 to expand and the upward movement of the bellows-closing plate 80 is transmitted through a helical spring 119 to deflect the centre portion of a flat spring 97 until the opposing forces of the spring 97 and the bellows plate 80 reach equilibrium. The static pressure exerted by the spring 119 up to the equilibrium stage maintain a valve seal 118 of a travelling valve 100 in closed relation to a valve aperture 82 in plate 80 and at the same time a flexible drive chain 130, attached to the lower end of the valve 100, rotates a drive sector 134 connected to a motion drive shaft 136. If an excessively high pressure is applied through port 140 relative to port 142, the bellows 56 is expanded to a limit where the valve 125 is closed to cut off any further pressure supply from the cavity 24 to the interior of the bellows 56 and thus prevents further expansion of the bellows 56. Should the pressure within the bellows 56 increase for some reason such as temperature, the pressure acting on the plate 80 will lift the plate 80 off the seal 118 to relieve such pressure. If the fluid presure applied to the port 142 is excessively high relative to the pressure through port 140, the bellows 56 will contract and the folds 60 will be forced into fully closed, superposed, supporting contact with one another and the closure plate 80 will rest upon and be supported by an annular stop member 88. In the event of any further pressure increase through port 142, the seal 118 will be forced out of sealing contact with the plate 80 to relieve such pressure.