Flow metering circuit and method

Claim 2

A circuit arrangement for use in a fluid metering device for providing an output signal accurately representing a fluid flow, said metering device sampling the fluid flow and providing a multiphase flow signal including a plurality of input phase signals conjointly representing the fluid flow, wherein said circuit arrangement comprises: reference-sequence means responsive to each said input phase signal for deriving therefrom a reference sequence of instantaneous graduated reference levels; comparison means responsive to each said input phase signal for comparing each said signal to a cross-associated reference sequence; reference-crossed means connected to said comparison means for providing a reference-crossed signal associated with each said input phase signal, each said reference-crossed signal indicating the moment and direction said input phase signal crosses the levels of the cross-associated reference sequence; and logic means responsive to said reference-crossed signals for providing an output signal indicating the amount and direction of said fluid flow.

Claim 3

The apparatus of claim 1, wherein said reference-sequence means includes means for deriving an oscillatory signal from each said input phase signal, said reference sequences being derived from said oscillatory signals.

Claim 4

The apparatus of claim 2, wherein said reference-crossed means includes means providing a pair of pulse trains, a first pulse train corresponding to ascending level crossings and a second pulse train corresponding to descending level crossings.

Claim 5

A circuit arrangement for use in a fluid metering device for providing an output signal accurately representing a fluid flow, said metering device sampling the fluid flow and providing first and second input phase signals conjointly representing said flow, wherein said circuit arrangement comprises: first and second reference-sequence means responsive to said first and second input phase signals, respectively, for deriving therefrom first and second reference sequences of instantaneous graduated reference levels; first and second assemblies of comparators responsive to said first and second input phase signals and to the reference levels of said first and second sequences, respectively, for determining when each reference level is crossed; first and second pulse train means connected to said first and second assemblies of comparators, respectively, each said pulse train means generating a pair of pulse trains, a first pulse train of each pair indicating the rate at which the respective reference levels are ascendingly crossed and a second pulse train of each pair indicating the rate at which the respective reference levels are descendingly crossed; flow-signal means responsive to said pulse trains for providing a pair of flow signals, a first flow signal indicating the rate of flow in a first direction and a second flow signal indicating the rate of flow in the opposite direction.

Claim 6

A circuit arrangement for use in a fluid metering device for providing an output signal accurately representing a fluid flow, said metering device sampling the fluid flow and providing first and second input phase signals conjointly representing said flow, wherein said circuit arrangement comprises: first and second reference-sequence means responsive to said first and second input phase signals, respectively, for deriving therefrom first and second reference sequences of instantaneous graduated reference levels; first and second assemblies of comparators responsive to said first and second input phase signals and to the reference levels of said first and second sequences, respectively, for determining when each reference level is crossed; first and second pulse train means connected to said first and second assemblies of comparators, respectively, each said pulse train means generating a pair of pulse trains, a first pulse train of each pair indicating the rate at which the respective reference levels are ascendingly crossed and a second pulse train of each pair indicating the rate at which the respective reference levels are descendingly crossed; flow-signal means responsive to said pulse trains for providing a pair of flow signals, a first flow signal indicating the rate of flow in a first direction and a second flow signal indicating the rate of flow in the opposite direction.

Claim 7

The apparatus of claim 4, further comprising: first and second demodulation means for deriving first and second oscillatory signals from said first and second input phase signals, respectively, said oscillatory signals having a frequency related to the fluid flow rate and a relative phase related to the fluid flow direction; said reference-sequence means deriving said reference sequences from said oscillatory signals and said assemblies of comparators comparing respective oscillatory signals with said reference levels.

Claim 8

The apparatus of claim 4 wherein said flow-signal means comprises a logic gate array receiving said pulse trains.

Claim 11

The method of claim 7, wherein each said reference-crossed signal comprises a pulse train having pulses spaced to correspond to said level crossings.

Claim 12

The method of claim 7, wherein each said reference-crossed signal comprises first and second pulse trains having pulses spaced to correspond to said level crossings, said first pulse train corresponding to ascending level crossings and said second pulse train corresponding to descending level crossings.