THERMAL AIR FLOW RATE SENSOR AND METHOD FOR FORMING IT

摘要

PROBLEM TO BE SOLVED: To provide a thermal air flow rate sensor for measuring an air flow rate using a heating resistor formed in a diaphragm whose periphery is fixed, which can prevent fracture of a diaphragm due to collision of dust. SOLUTION: Two or more step tapers are formed at the fixing end part for a diaphragm. The angle of the innermost taper is set to be smaller than that of the taper next to the innermost taper. When dust collides with the diaphragm and the kinetic energy of the dust is converted into the strain energy, fracture of the diaphragm is prevented by reducing the inclination of the load versus deflection curve near the end part of the diaphragm in order to reduce the generated load.