Flow meter for air or other gases - with fast response and linear relation between flow velocity and indication

摘要

The flowmeter can be used for air in vehicle fuel injection systems or for mass flow measurement of gases in the process industries. A tube of arbitrary cross-section forms a measuring chamber in which a magnetic field is established normal to the flow. Electrode plates are arranged parallel to the magnetic field and to the direction of flow and the measuring chamber is irradiated with ultra-violet light to increase the electron or ion concentration in the flow. The signals generated at the electrode plates as a result of the magnetic field and the flow velocity are fed to a subtraction amplifier with very high input impedance which determines the flow velocity from the difference between these signals.