Flow rate detecting device

Claim 1

A flow rate detecting device, comprising: a conduit having a flow passage defined therein for directing a fluid flow to be detected, in a straightforward direction along said passage; fluid flow rotating means immovably disposed in said passage, for converting the fluid flow in said passage from a straightforward flow into a rotary flow in said passage; a spherical member receiver disposed in said passage spaced from said fluid flow rotating means in a downstream direction with respect thereto, said receiver having a receiving face in said passage perpendicular to said straightforward direction; said conduit including an intermediate flow path member having an inner face of circular cross section, extending in said straightforward direction between said fluid flow rotating means and said spherical member receiver; a spherical member freely movably disposed in a space bounded by said fluid flow rotating means, said spherical member receiver and said inner face; and a revolution detecting means for detecting a number of revolutions of said spherical member about the center axis of said inner face; said fluid flow rotating means including a fixed blade having a protruding portion at a downstream end thereof, said protruding portion extending toward said spherical member receiver in alignment with said center axis of said inner face and terminating at a free end thereof upstream of the center of said spherical member, said free end being located a distance from said receiving face less than the diameter of said spherical member, said spherical member receiver having openings therein radially inward and outward of said receiving face respectively defining central and circumferential outflow paths directing the fluid flow therethrough.