Pivotable vane flowmeter with capacitive position sensor

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

• a) a pivotable member receiving a fluid dynamic torque from a flow of media disposed in a flow stream of the media pivotally about a pivot axis;
• b) means for providing a bias torque counter-acting the fluid dynamic torque received by the pivotable member;
• and
• c) means for measuring pivotal position of the pivotable member about the pivot axis as a measure of dynamic pressure of the flow of media, said means for measuring pivotal position including;
• i) an electrically conductive stub member with a surface area;
• ii) an electrically conductive elongated member with a surface area having a finite value of ohmic resistance per unit length thereof disposed closely adjacent to the electrically conductive stub member in a relationship allowing relative movement between the electrically conductive stub member and the electrically conductive elongated member in directions following a length of the electrically conductive elongated member, said relative movement being kinematically coupled to the pivoting movement of the pivotable member about the pivot axis;
• wherein the surface area of the electrically conductive stub member maintains a closely adjacent surface-to-surface relationship with a portion of the surface area of the electrically conductive elongated member during the pivoting movement of the pivotable member about the pivot axis;
• iii) means for supplying an alternating electrical signal to one of the following three elements:
• the electrically conductive stub member and two opposite extremities of the electrically conductive elongated member;
• and
• iv) means for obtaining an electrical variable representing a phase angle difference between two alternating electrical signals respectively taken off from two of the following three elements:
• the electrically conductive stub member and the two opposite extremities of the electrically conductive elongated member, as a measure of dynamic pressure of the flow of media.

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

• a) a pivotable member receiving a fluid dynamic torque from a flow of media disposed in a flow stream of the media pivotally about a pivot axis;
• b) means for providing a bias torque counter-acting the fluid dynamic torque received by the pivotable member;
• and
• c) means for measuring pivotal position of the pivotable member about the pivot axis as a measure of dynamic pressure of the flow of media, said means for measuring pivotal position including;
• i) an electrically conductive stub member with a surface area;
• ii) a pair of electrically conductive elongated members disposed in a parallel relationship to one another, each of said pair of electrically conductive elongated members having a surface area and a finite ohmic resistance per unit length thereof and disposed closely adjacent to the electrically conductive stub member in a relationship allowing relative movement between the electrically conductive stub member and the combination of the pair of electrically conductive elongated members in directions following a length of the combination of the pair of electrically conductive elongated members, said relative/movement being kinematically coupled to the pivoting movement of the pivotable member about the pivot axis;
• wherein the surface area of the electrically conductive stub member maintains a closely adjacent surface-to-surface relationship with a portion of the surface area of each of the pair of electrically conductive elongated members during the pivoting movement of the pivotable member about the pivot axis;
• iii) means for supplying an alternating electrical signal to at least one of two opposite extremities of a first of the pair of electrically conductive elongated members;
• and
• iv) means for obtaining an electrical variable representing a phase angle difference between two alternating electrical signals respectively taken off from two of the following three elements;
• the other of the two opposite extremities of the first of the pair of electrically conductive elongated members opposite to said one extremity, and two opposite extremities of second of the pair of electrically conductive elongated members, as a measure of dynamic pressure of the flow of media.