Patent ID: 7617739
Filing Date: 2009-11-17
Classification: G01L

Abstract:
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 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.