Improvements in or relating to spring mechanisms and control apparatus incorporating such mechanisms

摘要

1,055,547. Fluid analogue computers. HONEYWELL Inc. Oct. 6, 1965 [Oct. 12, 1964], No.42442/65. Heading G3H. [Also in Division F2] A pneumatic control apparatus 10 includes a spring mechanism (see Division F2) a pivoted plate 12 which forms part of the spring mechanism having adjustably mounted thereon a nozzle 52. A flapper 56 pivots about its mid-portion on the edge of the nozzle structure, one end of the flapper 56 co-operating with the nozzle 52 and the other end with an actuating arm 96 of an input unit 18. The position of the arm 96 is adjustable by a coarse adjusting screw 98 and a fine adjusting screw 104. The input unit 18 is fed with a constant pressure signal and a variable signal through a direct reverse acting switch 118 to actuate the flapper 56. The nozzle 52 is fed from a compressed air source through a tube 136, a filter, 138, a restriction 140 and a tube 142, a branch 144 from the tube 142 being connected to a pilot valve 132. The valve 132 amplifies the signal which is then transmitted to a rate unit 148 and subsequently to a capsule 152. The capsule 152 engages a cylindrical piston 46 depending from the plate 12 to apply a force to the plate in the form of feedback. Further feedback is applied to the plate by means of a reset capsule 192 acting on a further cylindrical piston 44 mounted on the plate at the opposite side from the pivot axis of the plate to the piston 46. A signal is applied to the reset capsule 192 through manually adjustable valves 160, 186 and a reset chamber 190 from a connection to the pilot valve 132 and the rate unit 148. The outlet conduit 170 of the pilot valve 132 is connected to an output conduit 226 for connection to a controlled element, for example a control valve in a process line, the pressure on the conduit 226 being varied in operation by the control apparatus 10 in dependence upon the difference in signals applied to the input unit 18.