Control of fluid pressure relays

摘要

1,000,104. Valves. ROBERTSHAW CONTROLS CO. Feb. 14, 1963 [Feb. 27, 1962], No. 6070/63. Heading F2V. [Also in Division G3] A pneumatic relay responsive to temperature or both temperature and pressure signals, has the signal transmitted to the pilot valve by a lever system. A lever 13, pivoted about an adjustable pivot C, Fig. 6, and pivots A and B, receives a temperature signal supplied by a temperature responsive device 10 through a lever 11 connected to point A, and a pressure signal fed through a diaphragm 50, lever 52 and lever 58 which is connected to point B. A lever 14 on the lever 58 is adjustable to vary the proportion of the pressure signal from zero. The lever 13 carries a changeover lever 21 movable from the full line position to the dotted line position to provide direct or reverse actuation of a lever 22 through a cam 21a, which abuts cams 24 or 25. Movement of the lever 22 is imparted to a bearing point 26 of triangular lever 27 connected to a fixed pivot 28. The lever 27 has a centrally positioned bearing lug 31 which abuts a hinged pilot valve 32 controlling leakage from a nozzle 34. Feedback from the relay may be provided through levers 39 and 43, the latter acting at 481 on the lever 27, the amount of the feedback signal being adjusted by a lever 37 from zero. The pneumatic relay comprises a fluid supply 47, Fig. 7, fed to a chamber 72 and past a valve 77 to a signal outlet- 40. A valve member 82 carried by diaphragms 81, 90 co-operates with the stem 86 of valve 77 to control flow from the chamber 78 to exhaust. The valve 82 and hence valve 77 is positioned by the pressure in the chamber 91 which is controlled by the pilot valve 32, whereby the relay output signal is proportional to the input signal to the lever system.