GB1374775A - Fluidic porximity sensor - Google Patents

Abstract

1374775 Fluid operated gauges BOWLES FLUIDICS CORP 11 Oct 1971 47321/71 Heading G1M A proximity gauge, Figs.1, 2, comprises a fluid inlet 9 in a block 1 and ducts 4 to cause air to vortex in a chamber 2. A sensing tube 11 has apertures 13 so that the air may also enter the tube and increase the static pressure inside the rotating helical jet issuing from the passage 7 so that the jet is increased in length and its range of detection increased. When the jet or vortical sheet as it is called is impeded the static pressure inside the sheet increases to indicate the proximity of an object to the sheet. Best results are obtained when the static pressure at restriction 12, in the absence of a detected object, is ambient and the pressure at the end of tube 11 is just slightly below ambient. In Figs.3 and 4 (not shown) the block 1 is surmounted by a further block (28) having a fluidic OR/NOR gate (29) which applies a quiescent bias pressure to a control passage (31) so that the static pressure in tube (24) is lowered and thus increases the switching sensitivity of the gate in response to object detection. In Fig.6 the sensing tube 67 has a tapered bore 71 communicating via chamber 73 and bleed channel 79 with vortex chamber 49. The bore 71 also leads to a chamber 81a having a diaphragm 83 pressurized on its otherside 81b and acting as a flapper valve which closes off or opens up a nozzle 85 connected to a back pressure gauge operating on the Venturi principle such as that indicated in Figs.10, 11 (not shown). If a device is to have a range between two limits then by passing the object under two proximity detectors it is possible to decide whether it lies within such a range.