Fluid flow meters

Claim 2

A flow meter comprising a pair of piezoelectric crystals mounted in association with a fluid conduit and spaced from each other in a non-rectangular direction to the axis of the fluid conduit; means to apply an electrical pulse train to one of said crystals to generate a sonic signal which is transmitted through said fluid conduit in said non-rectangular direction and received by the other of said crystals to generate a first electrical signal responsive to said sonic signal; means to establish a reference signal; means to discontinue the application of electrical pulses to said one crystal and to apply a second electrical pulse train to said other crystal to generate a second sonic signal which is transmitted through said fluid conduit along the aforementioned non-rectangular direction and received by said one crystal to generate a second electrical signal responsive to said second sonic signal transmitted through said fluid conduit; means to compare said first and second electrical signals with said reference signal to produce signals which are responsive to the delay times in the transmission of said sonic signals through said fluid conduit; means for deriving a third signal from said signals which are responsive to the delay times of said sonic signals, said third signal being responsive to the fluid velocity in said fluid conduit.

Claim 3

The flow meter of claim 1 in which the crystals are positioned at terminal ends of a tube intersecting the fluid conduit at a non-rectangular angle and having a diameter substantially equal to the diameter of the fluid conduit at said intersection.

Claim 4

The flow meter of claim 1, including an oscillator for generating a high frequency square wave; means responsive to said high frequency square wave for producing respective pulse trains herein referred to as alpha, beta and gamma pulses, said alpha and beta pulses comprising a series of pulse trains of said high frequency square wave for predetermined periods, said pulse trains spaced in time from each other responsive to the time of transmission of the sonic signals from one crystal to the other crystal, and said gamma pulses occurring during a portion only of the duration of each of the alpha and beta pulses; whereby said means to apply an electrical pulse train to one of said crystals applies said alpha pulses to said one crystal and said means to discontinue the application of electrical pulses to said one crystal and to apply a second electrical pulse train to said other crystal terminates said application of said alpha pulses and applies said beta pulses to the other of said crystals; means to terminate the application of said beta pulses thereby generating said sonic signals alternatively by said crystals; means associated with said crystals to generate said first and second electrical signals as alternate trains of square wave pulses responsive to said sonic signals received at said crystals; means responsive to said gamma train of pulses to transmit a high frequency pulse during the application of said gamma signal; said means to establish a reference signal including means to generate a reference pulse responsive to said high frequency square wave from said oscillator, said reference pulse being at substantially a higher frequency than said high frequency square wave and said means to compare said first and second electrical signals with said reference signal including means to compare the time delay between said reference pulse and the square wave pulses responsive to said received sonic signal generated alternatively by the alpha and beta pulses to thereby produce said signals which are responsive to the delay times.

Claim 5

The flow meter of claim 3 in which the crystals are positioned at terminal ends of a tube intersecting the fluid conduit at a non-rectangular angle and having a diameter substantially equal to the diameter of the fluid conduit at said intersection.

Claim 6

In the flow meter of claim 3, a gate system for said alternate trains of square wave pulses responsive to the received sonic signal, said gate system conprising means to invert said high frequency square wave from said oscillator and means to invert said gamma pulses and a frequency phase control, said frequency phase control including a NOR gate and a D-type flip-flop, means to apply said inverted gamma pulses to said NOR gate, means including said D-type flip-flop to actuate said gate system to alternately apply said high frequency square wave and said inverted high frequency square wave to said frequency phase control, said gate system connecting the output of the crystal receiving said sonic signal to said frequency phase control and the input of said frequency phase control connected to said NOR gate, said NOR gate activating said D-type flip-flop when all of the inputs to the NOR gate are (0); one of the output terminals of said frequency phase control connected on one side to the set side of a D-type flip-flop and the other output terminal of said frequency phase control to the reset side of the said D-type flip-flop; said means to compare said first and second electrical signals including a flip-flop and means to connect the output of the flip-flop to an integration circuit, the voltage at said integration circuit being a measurE of the difference in the delay times of the sonic signal when the alpha pulse train and the beta pulse train are applied.

Claim 7

The flow meter of claim 5 in which the crystals are positioned at terminal ends of a tube intersecting the fluid conduit at a non-rectangular angle and having a diameter substantially equal to the diameter of the fluid conduit at said intersection.