Patent ID: 6725716
Filing Date: 2004-04-27
Classification: G01F

Abstract:
A thermo-sensitive flow rate sensor having a flow rate detecting device comprising:a plate-like substrate having a top surface and a back surface side, said back surface side being opposite to said top surface; a support portion disposed on said top surface of said plate-like substrate; a heating element and a temperature compensating element constituted by thermo-sensitive resistance films respectively disposed on said support portion of said substrate in such a way as to be spaced apart from each other; and a low heat capacity portion formed in said back surface side of said substrate under an area where said heating element is disposed, said thermo-sensitive flow rate sensor being operative to measure a flow velocity or flow rate of a measurement fluid according to a heat transfer phenomenon where heat is transferred from said heating element or from a portion heated by said heating element to the measurement fluid, wherein a diaphragm is constructed by forming at least one cavity by removing partially a region, other than the area under which said heating element and said temperature compensating element are formed, of the substrate from the back surface side thereof, so as to reach said support portion, said diaphragm being electrically insulated from said heating element and said temperature compensating element.