Patent ID: 6189380
Filing Date: 2001-02-20
Classification: G01F

Abstract:
A flow rate sensor havinga fluid passage for a fluid to flow therealong;a temperature sensing element for sensing a temperature of the fluid;a detecting element including a flow rate detecting resistance made of a thermo-sensitive electrically resistant material, said detecting element being disposed in the fluid passage so as to expose the flow rate detecting resistance to said fluid flowing therethrough; anda control circuit for controlling an electric current flowing into the flow rate detecting resistance such that the temperature of the flow rate detecting resistance may be maintained at a predetermined value which is higher to some extent than a fluid temperature detected by the temperature sensing element;wherein said flow rate sensor measures the flow rate of said fluid flowing along said fluid passage on a basis of a heat transfer phenomenon from the flow rate detecting resistance to said fluid, comprising;a main body structure formed such that a cross section perpendicular to a central axis becomes larger from a front end towards a rear end therefore; said main body structure supported by a support section formed protrudingly on an internal surface of said fluid passage, and positioned within said fluid passage so as to turn a front end thereof to an upstream side of said fluid and so as to turn a rear end thereof to a downstream side of said fluid,wherein said detecting element is disposed between said main body structure and the internal surface of said fluid passage.