Patent ID: 7454982

Claim:
A flow meter for measuring fuel fluid flow from a fuel injector, comprising: a conduit located downstream of the fuel injector comprising at least two pressure sensors spaced from each other longitudinally along the length of the conduit; wherein the conduit is configured to allow fuel to flow through the conduit, and each sensor is configured to at least detect the presence of fuel fluid flow in the conduit or detect a property of fuel fluid in the conduit that indicates presence of fuel fluid in the conduit; a data processing unit connected to the pressure sensors to receive signals from the pressure sensors, wherein the data processing unit calculates a pressure gradient from the signals received from the pressure sensors and from the pressure gradient calculation calculates one or more of flow velocity or volumetric flow rate of a fluid flowing in the conduit using a non-iterative calculation; wherein the pressure gradient is calculated by at least one of a direct method, a time of flight method or a combination thereof; wherein the direct method involves measuring the pressure exerted by the pressure wave by the pressure sensors, then the measured pressure is converted to the pressure gradient by dividing the difference in the measured pressure by the distance between the pressure sensors; wherein the time of flight method involves measuring the time it takes the pressure wave to travel from one pressure sensor to the other pressure sensor to determine the time constant, then the time constant is calculated by using a spectral method, or a time correlation method; wherein the pressure sensors are angularly offset from one another; and wherein the pressure sensors are configured so as not to obstruct fuel fluid flow.