PURPOSE: To provide a mass flow sensor with high sensitivity and zero point stability by installing a heating element at a position, which is a middle point of a pair of heat sensitive elements and parted spatially from them and forming a temperature field having sharp temperature gradient between the heat sensitive elements and the heating element.
CONSTITUTION: A mass flow sensor is composed of at least a pair of heat sensitive elements (123, 124), (125, 126) whose long sides are set face to face mutually and a heating element 150 and the heat sensitive elements (123, 124); (125, 126) and the heating element 150 form one temperature field. The coupled heat sensitive elements (123, 124), (125, 126) are positioned at thermally symmetric positions in the temperature field in no wind blowing condition and the heating element 150 is installed in parallel to the long sides of the coupled heat sensitive elements (123, 124) (125, 126) on a second plane parted from a first plane including the coupled heat sensitive elements (123, 124), (125, 126) at a prescribed distance while having an air layer between them.
OISHI MITSURU
UNO MASAHIRO
