Patent ID: 7120542
Filing Date: 2006-10-10
Classification: G01F,G05D

Abstract:
1. A flow monitoring system comprising: a first temperature-sensitive resistive device, thermally coupled to a first portion of a fluid transfer apparatus, for producing a first temperature-dependant voltage signal representative of the temperature of the fluid within the first portion of the fluid transfer apparatus; a first current control device, coupled to the first temperature-sensitive resistive device, for controlling a first current signal flowing through the first temperature-sensitive resistive device, wherein the first current controlling device includes (i) a first transistor for controlling the first current signal flowing through the first temperature-sensitive resistive device, (ii) a first amplification circuit coupled to the first transistor, wherein the first amplification circuit is responsive to a first control signal and provides a first control voltage to the first transistor, and (iii) a first control resistive device coupled to the first transistor, wherein the first current signal flows through the first control resistive device and generates a first feedback signal that is provided to the first amplification circuit; a second temperature-sensitive resistive device, thermally coupled to a second portion of the fluid transfer apparatus, for producing a second temperature-dependant voltage signal representative of the temperature of the fluid within the second portion of the fluid transfer apparatus; a second current control device, coupled to the second temperature-sensitive resistive device, for controlling a second current signal flowing through the second temperature-sensitive resistive device, wherein the second current controlling device includes (i) a second transistor for controlling the second current signal flowing through the second temperature-sensitive resistive device, and (ii) a second amplification circuit coupled to the second transistor, wherein the second amplification circuit is responsive to a second control signal and provides a second control voltage to the second transistor, and (iii) a second control resistive device coupled to the second transistor, wherein the second current signal flows through the second control resistive device and generates a second feedback signal that is provided to the second amplification circuit; a monitoring circuit for monitoring the first and second temperature-dependant voltage signals and producing an output signal representative of the volume of fluid passing through the fluid transfer apparatus; and a resistive calibration device, coupled to the first and second control resistive devices, for adjusting the resistive values associated with the first and second control resistive devices.