GB1457946A - Liquid flow controlling means - Google Patents

Abstract

1457946 Fluid-pressure servomotor system TYME VALVE CORP 21 Feb 1974 [7 Aug 1973] 7897/74 Heading G3P [Also in Division F2] A liquid supply system e.g. to distribute water to agricultural sprinklers, includes Figs. 3, 4, a master valve assembly comprising a main valvemember 18 co-operating with seat 20 to control liquid flow through body 11 to one part of the system, an actuating piston 30 (or diaphragm) attached to valve stem 19, and a pilot valve 37 operable at predetermined time intervals to bleed liquid pressure from the upper to the lower sides of piston 30 to actuate main valve-member 18, pilot valve 37 being controlled by follower 46 bearing on cam 45 driven by a battery powered transducer device 160. Actuating liquid is supplied to the upper side 36 of piston 30 from the main flow via passage 31 in valve stem 19 and port 33, thus holding main valve 18 closed providing pilot valve 37 is also closed. A cleaning rod 230 is provided in passage 31. When cam 45 opens valve 37, bleed liquid flows through port 42 and ducts 44, 52 to the lower side 36a of piston 30 causing upwards movement thereof to open main valve 18. Cam 45 is rotated e.g. once every four days i.e. “ turn a day and each lobe 47 is arranged to hold pilot valve 37 open for two hours. A second pilot valve 48 is associated with the latter and controlled by a cam 53 rotated once every four hours, valve 48 being open when follower 54 dwells in recess 156, e.g. for a period of five to sixty minutes per revolution. Main valve 18 is thus only open when both pilot valves 37, 48 are open. The battery powered transducer device 160 drives the cams by emitting mechanical pulses at 161 to wind a clock mechanism 70 comprising a torsion spring 80 driving an escapement 84 which drives the shaft 74 of cam 53 and via gearing 71, 72 &c. the shaft 56 of cam 45. Shaft 56 carries additional cams 57, 58 and can be axially moved within housing 22 by a manual plunger 61 to bring a different cam into engagement with follower 46 and thus vary the timing cycle. Cam 53 may be rotated on its shaft 74, e.g. by a watering time duration selector (75) Fig. 2 (not shown) via a friction drive, to shift it relative to follower 54, the angular extent of recess 156 and thus the watering time interval being a function of the axial displacement of cam 53. The selected interval is shown on an indicator (77). The pressure in bleed duct 52 may be communicated via line 185 to an actuator piston 203, Fig. 9 to control sequential operation of an auxiliary valve assembly in another part of the liquid distribution system and constructed in similar fashion to that already described. A drop in bleed pressure indicative of the closing of master valve 18 causes spring 210 to move piston 203 leftwards so that finger 205 operates switch arm 207 to close contact 208 and permit current to flow from battery 188 to rotate a clock mechanism 187. The latter rotates shaft 189 carrying a cam 183 to open the single pilot valve (182), Fig. 8 (not shown) of the auxiliary valve assembly. A line (185a) from the bleed duct (198, 199) of the latter controls sequential operation of a further auxiliary valve assembly. Rotation of cam 183 continues until follower 201 enters recess 192a in a further cam 192 carried by shaft 189, thus breaking the electric circuit. The clock mechanism 187 can also be started by a manual switch 240. In a modification Fig. 14 (not shown) the components of Fig. 9 are replaced by an actuator piston (387) responsive to bleed pressure communicated through line (385a) and operating the pilot valve (382) of the auxiliary valve assembly via a ratchet and pawl mechanism (395, 396) including a wind-up spring and escapement unit (394) causing slow closure of the pilot valve. In a further modification Figs. 11 to 13 (not shown) the actuating piston 30 of the master valve assembly is replaced by a diaphragm (330) and the single pilot valve (337) is operated by a pivoted lever (348) having spaced fingers (347, 350) engaging respective cams (345, 346) corresponding to the cams 45, 53 of Fig. 4. The pilot valve (337) opens only when both fingers engage recesses (349, 351) in the respective cams simultaneously. A control plate (357) rotating with cam (345) can mask a selected number of recesses (349) in the latter so as to vary the timing cycle. The cams (345, 346) are rotated via gearing by a battery energized transducer (368) comprising a vibrating tuning fork and an escapement. The travel of actuating diaphragm (330) can be selectively limited by a movable stop (370) adjusted manually by element (373) acting through bevel gears (375a). A manual bleed valve (377a) can over-ride pilot valve (337). A modified pilot valve, Fig. 10, comprises cam follower 184 having a stem 219 spaced in the valve open position from closure ring 221 to define a gap 220 permitting liquid to flow through port 224 to the bleed duct. When follower 184 is depressed, gap 220 diminishes such that liquid pressure urges ring 221 upwardly against shoulder 228 as shown in Fig. 10a. Simultaneously O-ring 227 moves upwardly to seal the gap between stem 219 and ring 221 and prevent flow to the bleed duct.