Patent ID: 7603915

Claim:
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 and including means for converting fluid inertia into flow induced torque when fluid flows relative to the impeller body; c) sensing means 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) electromagnetic means for generating a magnetic field about the impeller body that maintains the impeller body in a constant angular position with respect to the sensor housing when torque is applied to the impeller body; e) means for determining electrical values from the sensing means when fluid flows relative to the impeller body; and f) means for controlling electricity supplied to the electromagnetic means in response to electrical values determined from the sensing means, to generate a magnetic field sufficient to prevent rotation of the impeller body.