Volume flow measurement system
First Claim
1. A flow measurement device for obtaining a signal representive of the volume flow of a fluid, comprising:
- a first transducer for producing and for receiving acoustic waves capable of being modified by the flow of a fluid;
a second transducer for producing and for receiving acoustic waves capable of being modified by the flow of said fluid;
means for positioning said first and second transducers to illuminate substantially uniformly the entire diameter of said fluid flow by waves produced by said transducers, said transducers being so related that the fluid to be measured will have a component of flow along the axis of said waves;
first means for energizing said first transducer to produce a first beam of said waves for a first period of time in a first direction with respect to said component of flow;
said wave beam being directed to and received by said second transducer to produce first electrical signals representing the received waves;
second means for energizing said second transducer to produce a second beam of said waves for a second period of time in a second direction with respect to said component of flow, said second wave beam being directed to and received by said first transducer to produce second electrical signals representing the received waves;
said first and second means for energizing said first and second transducers comprising oscillator means producing a high frequency electrical output, normally deactivated first and second gate means connecting said oscillator output to said first and second transducers, respectively, and control means for periodically and alternately activating said first and second gate means in transmit modes to produce bursts of acoustic waves which travel between said first and second transducers;
receiver means responsive to said first and second electrical signals produced by said second and first transducers, respectively, said receiver means being connected to said first and second transducers by said first and second gate means, respectively, said control means periodically and alternately activating said gate means in receive modes to permit said first and second electrical signals to travel to said receiver means;
synchronous detector means connected to said receiver means and to said oscillator means for alternately comparing each of said first and second electrical signals with the high frequency output of said oscillator to produce corresponding alternate first and second variable signals;
integrator means for alternately integrating each of said first and second variable signals to produce first and second output signals corresponding to said first and second electrical signals; and
means responsive to the difference between said first and second output signals for producing a resultant signal which is proportional to the volume flow of said fluid.
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Accused Products
Abstract
An apparatus and method for direct measurement of the volume flow of fluids through a tube, using an interferometric transit time technique is disclosed. First and second transducers for producing and receiving waves which are capable of being modified by the flow of the fluid in the conduit are positioned so that the conduit is fully and evenly illuminated by the waves. The transducers are located with respect to the conduit so that there will be a component of fluid flow along the axis of the illuminating wave beam. Means are provided to first activate one transducer to transmit waves while the other is in a receive mode and thereafter to place the second transducer in a transmit mode while the first is switched to its receive mode. The received waves are converted to corresponding electric signals by the corresponding transducers, and these signals are periodically sampled and stored for comparison. The result of this comparison is an electric signal which is proportional to fluid flow and is to a high degree independent of flow profile, conduit geometry, and alignment of the conduit within the probe. The device is particularly useful in measuring the flow of blood through a vessel.
93 Citations
13 Claims
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1. A flow measurement device for obtaining a signal representive of the volume flow of a fluid, comprising:
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a first transducer for producing and for receiving acoustic waves capable of being modified by the flow of a fluid; a second transducer for producing and for receiving acoustic waves capable of being modified by the flow of said fluid; means for positioning said first and second transducers to illuminate substantially uniformly the entire diameter of said fluid flow by waves produced by said transducers, said transducers being so related that the fluid to be measured will have a component of flow along the axis of said waves; first means for energizing said first transducer to produce a first beam of said waves for a first period of time in a first direction with respect to said component of flow;
said wave beam being directed to and received by said second transducer to produce first electrical signals representing the received waves;second means for energizing said second transducer to produce a second beam of said waves for a second period of time in a second direction with respect to said component of flow, said second wave beam being directed to and received by said first transducer to produce second electrical signals representing the received waves; said first and second means for energizing said first and second transducers comprising oscillator means producing a high frequency electrical output, normally deactivated first and second gate means connecting said oscillator output to said first and second transducers, respectively, and control means for periodically and alternately activating said first and second gate means in transmit modes to produce bursts of acoustic waves which travel between said first and second transducers; receiver means responsive to said first and second electrical signals produced by said second and first transducers, respectively, said receiver means being connected to said first and second transducers by said first and second gate means, respectively, said control means periodically and alternately activating said gate means in receive modes to permit said first and second electrical signals to travel to said receiver means; synchronous detector means connected to said receiver means and to said oscillator means for alternately comparing each of said first and second electrical signals with the high frequency output of said oscillator to produce corresponding alternate first and second variable signals; integrator means for alternately integrating each of said first and second variable signals to produce first and second output signals corresponding to said first and second electrical signals; and means responsive to the difference between said first and second output signals for producing a resultant signal which is proportional to the volume flow of said fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A flow measurement system for obtaining a resultant signal representative of the volume flow of a fluid stream, comprising:
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first and second acoustic wave transducers adapted to be located adjacent the fluid stream, said transducers being so located that an acoustic wave beam transmitted by one transducer will pass through said fluid stream and will impinge on the other transducer; means for generating a drive signal for activating said transducers, said drive signal being of an amplitude and frequency sufficient to drive said transducers to produce ultrasonic wave beams, said transducers each producing a wave beam of sufficient dimension to illuminate with uniform intensity tne entire cross section of the portion of the fluid stream to be measured; control means for periodically and alternately switching said transducers between transmit and a receive modes, whereby said drive signal is applied to said first transducer and the resulting acoustic wave beam is received by said second transducer and thereafter said drive signal is applied to said second transducer and the resulting acoustic wave beam is received by said first transducer; synchronous detector means for comparing the signal received by said second transducer with said drive signal to provide a first variable signal and for comparing the signal received by said first transducer with said drive signal to provide a second variable signal; means for integrating each of said first and second variable signals to produce first and second output signals; and means responsive to the difference between said first and second output signals for producing a resultant signal which is proportional to the volume flow of said fluid stream. - View Dependent Claims (12, 13)
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Specification