| 摘要 |
A pressure ratio sensing device for generating an output fluid pressure differential signal in proportion to the ratio of two sensed fluid pressures. The output differential signal is derived from a pressurized supply fluid which flows subsonically through a first restriction, a second restriction defining a power jet for a dual output proportional acting fluidic amplifier having opposed control fluid ports, a vortex amplifier having a radial supply port and a tangential control port, and a third restriction to the lower of the two sensed fluid pressures. The fluid pressure intermediate the first and second restrictions is controlled to maintain the same in excess of the higher of the two sensed fluid pressures. The higher of the two sensed pressures is applied to one of the opposed control fluid ports of the proportional amplifier to bias the power jet thereof toward one of the dual outputs which, in turn, is vented to the tangential port of the vortex amplifier. The remaining of the dual outputs is vented to the radial supply port of the vortex amplifier as well as to the second of the control ports of the proportional amplifier. The pressure drop across the third restriction provides the output pressure differential signal which varies in proportion to the ratio of the sensed two fluid pressures. The effective flow area of the third restriction is such that the pressure differential thereacross does not exceed the expected minimum pressure of the lower of the two sensed fluid pressures.
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