Electromagnetic velocity transducer

Claim 1

A transducer for generating an electrical signal that is a function of the velocity of a flowing body of liquid having a surface comprising: (a) a submergible body having an upper surface and a lower surface; (b) means located within the submergible body for imposing a magnetic field transverse to the direction of flow of the liquid, said means comprising: (1) a ferromagnetic core including two coplanar U-shaped members substantially transverse to the direction of flow and separated by a preselected distance, the U-shaped members being arranged with respect to the body so that the resultant vector of the radiated field is directed from the upper surface of the body toward the surface of the body of liquid; and (2) A coil surrounding the inner legs of the U-shaped members and wound upon a bobbin of electrically insulative material; (c) A pair of measuring electrodes lying along a line substantially coincident with the direction of the cross product of said magnetic field vector and said velocity; (d) a circuit for deriving an electrical signal representing the potential difference between said measuring electrodes, whereby said electrical signal is a function of the average velocity of flow over said preselected distance; and (e) means for conducting the electrical potential of each of said measuring electrodes to said circuit, said conducting means comprising: (1) a first wire providing electrical connection between one of said measuring electrodes and said circuit; (2) a second wire providing electrical connection between the other of said measuring electrodes and said circuit; (3) said bobbin having an upper surface and a lower surface; and (4) portions of said first wire and of said second wire forming in combination a generally s-shaped geometry at the upper surface of said bobbin whereby oppositely directed cancelling currents are induced at a no-flow condition.