| 摘要 |
<p>1282924 Fluid logic and switching circuits PLESSEY CO Ltd 18 Aug 1970 [23 Aug 1969] 42117/69 Headings F1G and F1P An actuator piston 25 is held in one or other extreme position according to whether output leg 20 or 22 of a fluidic device 6, e.g. a bi-stable element having a supply input line 8 and control inlets 12, 14 is pressurized; control inlet 14 being supplied at a pressure PR from a Venturi tube 18 which receives fluid from a source 16 at a pressure PV which is proportional to supply input pressure P 4 whereby the output is switched from leg 20 to leg 22 when the ratio of P 4 to PF reaches a predetermined value. As shown the Venturi 18 is fed from a vent of the interaction volume of the element 6 and when due to an input pressure rise and hence an increase in vent pressure PV sufficient to choke the Venturi throat the resulting rise in pressure PR in control input 14 switches the output from leg 20 to leg 22. The actuator piston 25 then closes a switch 26 which may control the fuel supply to a turbine having a high-pressure stage 7 and a fan stage 9 which respectively provide the supply pressure P 4 and control pressure PF. Alternatively the switch 26 may control an air valve 13. In a modification the Venturi is supplied directly from the high-pressure supply and in a further modification the fluidic element is a proportional amplifier (32), Fig. 3 (not shown).</p> |
