Non-invasive ultrasonic system to determine internal pressure in flexible tubing
First Claim
1. A system for determining change in pressure of a liquid flowing in a tube of an elastic material that has a base line value for travel time of an electro-mechanical energy signal transmitted through the tube due to one of pressure of the liquid of a known value flowing in the tube or no liquid flowing in the tube acting against the tube elastic material, comprising:
- a pair of piezoelectric elements between which the tube is placed with said elements opposing each other generally transverse to the direction of liquid flowing in the tube;
a circuit for storing said base line travel time value; and
an electronic circuit forproviding periodic bursts of signals to one of said pair of elements to transmit electro-mechanical energy through the tube wall into and across its interior and any liquid flowing therein and out the tube wall to be received by the other of said pair of elements to be converted to an electrical signal,measuring the travel time value of said energy through the tube from the electrical signal, andcomparing the measured travel time value that changes due to the pressure of the liquid flowing in the elastic tube causing it to expand or contract to the stored base line travel time value to determine a change of pressure of liquid flowing in the tube from that which would be flowing as measured by said travel time base line value.
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Accused Products
Abstract
A system for determining pressure change in a liquid flowing in a tube of an elastic material has a sensor head having a slot and a pair of piezoelectric elements mounted in opposing walls of said slot between which the tube is placed in contact with the opposing elements. An electronic circuit generates periodic bursts of electro-mechanical energy from one of the elements that is transmitted through the tube to be received by the other element to be converted to an electrical signal from which is measured the travel time value of the energy through the tube and liquid therein and the amplitude value of the received signal which values are compared to at least one of base line travel time and amplitude values to determine a change of pressure of the liquid flowing in the tube.
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Citations
21 Claims
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1. A system for determining change in pressure of a liquid flowing in a tube of an elastic material that has a base line value for travel time of an electro-mechanical energy signal transmitted through the tube due to one of pressure of the liquid of a known value flowing in the tube or no liquid flowing in the tube acting against the tube elastic material, comprising:
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a pair of piezoelectric elements between which the tube is placed with said elements opposing each other generally transverse to the direction of liquid flowing in the tube; a circuit for storing said base line travel time value; and an electronic circuit for providing periodic bursts of signals to one of said pair of elements to transmit electro-mechanical energy through the tube wall into and across its interior and any liquid flowing therein and out the tube wall to be received by the other of said pair of elements to be converted to an electrical signal, measuring the travel time value of said energy through the tube from the electrical signal, and comparing the measured travel time value that changes due to the pressure of the liquid flowing in the elastic tube causing it to expand or contract to the stored base line travel time value to determine a change of pressure of liquid flowing in the tube from that which would be flowing as measured by said travel time base line value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for determining change in pressure of a liquid flowing in a tube of an elastic material comprising the steps of:
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establishing a base line value for travel time of an electro-mechanical energy signal transmitted through the tube due to one of pressure of the liquid of a known value flowing in the tube or no liquid flowing in the tube acting against the tube elastic material; storing said base line travel time value; providing a pair of opposing spaced apart piezoelectric elements and placing the tube between said opposing elements with said elements of said pair being generally transverse to the direction of liquid flowing in the tube; providing periodic bursts of signals to one of said pair of elements to transmit electro-mechanical energy through the tube wall into and across its interior and any liquid flowing therein and out the tube wall to be received by the other of said pair of elements to be converted to an electrical signal, measuring the travel time value of said energy through the tube from the electrical signal; and comparing the measured travel time value that changes due to the pressure of the liquid flowing in the elastic tube causing it to expand or contract to the stored base line travel time values to determine a change of pressure of liquid flowing in the tube from that which would be flowing as measured by said travel time base line value.
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Specification