Turbine flowmeter with capacitive transducer

An apparatus for measuring flow rate of media comprising in combination:

• a) a rotary member disposed in a flow stream of fluid media rotatably about an axis of rotation, wherein flow of the fluid media exerts a fluid dynamic torque on the rotary member and rotates the rotary member about the axis of rotation;
• b) at least one first discrete electrically conductive member having a first surface of a sizable area and rotating with the rotary member about the axis of rotation, said first surface substantially coinciding with a hypothetical surface defined by rotation of a line of intersection between the first surface and a plane including the axis of rotation about the axis of rotation;
• c) a second and third discrete electrically conductive member respectively having a second and third surface of sizable area, said second and third surfaces disposed in a stationary manner on a surface substantially coaxial and closely adjacent to said hypothetical surface, wherein the first surface of the first discrete electrically conductive member intermittently establishes a surface-to-surface proximity relationship commonly with the second and third surfaces of the second and third discrete electrically conductive members during rotation of the rotary member about the axis of rotation;
• whereby the first discrete electrically conductive member establishes an intermittent capacitive electrical coupling between the second and third discrete electrically conductive members during the rotation of the rotary member;
• d) means for obtaining an output electrical signal representing an amplitude modulation created by the rotation of the rotary member about the axis of rotation from a fluctuating electrical signal taken off from one of the second and third discrete electrically conductive members;
• and
• e) means for measuring frequency of the output electrical signal as a measure of volume flow rate of the fluid media.