Patent ID: 6339959
Filing Date: 2002-01-22
Classification: G01F

Abstract:
A flow meter for measuring the flow rate of a fluid comprising:a tubular conduit for passing the fluid therethrough, a float member, disposed within the conduit capable of displacement from a neutral position by a drag imposed thereon by the fluid, at least a portion of said float member is made of magnetically responsive material, a differential transformer surrounding the conduit comprising two separate coils connected to a variable resistor, said differential transformer providing a responsive electrical signal upon displacement of the float member from the neutral position, a magnetic means operatively associated with the conduit for exerting on the float member a magnetic force sufficient to retain the float member in the neutral position, a source of alternating voltage connected to said differential transformer, a signal processing means connected to the differential transformer for processing the responsive signal produced by the differential transformer and for controlling the magnetic means, by outputting a control current signal to said magnetic means, a source of reference voltage, said source of reference voltage connected to a calculating means for deriving the flow rate from the control current signal, the input of the calculating means is connected to the output of the signal processing means and to the output of the source of reference voltage, a display means connected to the output of the calculating means for visual representation of the derived flow rate value, wherein said magnetic means is configured as a solenoid, which closely surrounds the conduit, the inwardly facing surface of the solenoid matches the outwardly facing surface of the conduit, said solenoid resides between the coils of the differential transformer means and is connected to the output of the signal processing means and wherein said signal processing means includes a subtracting means, a first amplifier, a rectifier, an RC circuit, a second amplifier and an inverter means, connected in series for outputting the control current signal to the magnetic means and calculating means.