Force balanced impeller flow meter for mass flow rate control

A force balanced mass flow meter comprising:

• a) a cylindrical sensor housing having an interior bore;
• b) an impeller body supported for axial rotation within the interior bore of the sensor housing, the impeller body having a fluid flow path extending therethrough configured to generate flow induced torque with respect to the impeller body;
• c) a capacitive angular position sensor locationally associated with an exterior surface of the impeller body and an interior surface of the interior bore of the sensor housing for measuring a rotation angle of the impeller body relative to the sensor housing;
• d) a plurality of permanent magnets positioned in the impeller body about a circumference thereof;
• e) a stator surrounding the sensor housing aligned with the permanent magnets for generating a magnetic field to prevent rotation of the impeller body;
• f) capacitance pick-off electronics for determining capacitance values from the capacitive angular position sensor when fluid flows through the impeller body;
• and
• g) a proportional-integral-derivative controller for controlling current supplied to the stator in response to capacitance values from the sensing means, to generate a magnetic field sufficient to prevent impeller rotation, wherein the current supplied to the stator is proportional to flow induced torque applied to the impeller body.

A force balanced mass flow meter comprising:

• a) fixed non-rotating tubular swirler configured to convert an incoming fluid flow into an outgoing helical swirl flow;
• b) a freely rotatable flow induced torque measuring assembly communicating with the tubular swirler and configured to measure a torque value of the helical swirl flow generated by the tubular swirler;
• and
• c) a closed loop control based electromagnetic system configured to generate electromagnetic forces that prevent the flow induced torque measuring assembly from rotating under the influence of the helical swirl flow.