Force balanced impeller flow meter for mass flow rate control

摘要

A force balanced mass flow meter is disclosed that includes a cylindrical sensor housing having an interior bore, an impeller body supported for axial rotation within the interior bore of the sensor housing, and including structure for converting fluid inertia into flow induced torque when fluid flows relative to the impeller body, a proximity sensor for measuring a rotation angle of the impeller body relative to the sensor housing, an electromagnet for generating a magnetic field about the sensor housing to prevent rotation of the impeller body, electronics for determining electrical values from the proximity sensor when fluid flows relative to the impeller body and a controller for controlling current supplied to the electromagnet in response to electrical values determined from the proximity sensor, to generate a magnetic field sufficient to prevent impeller rotation.