AIR FLOWMETER

摘要

PURPOSE:To provide an air flowmeter which can suppress the variation of its output characteristics even when dust adheres to an exothermic resistor element for measuring air flow rate and has an excellent contamination resistance. CONSTITUTION:An exothermic resistor element 3 for measuring air flow rates positioned in an auxiliary passage 6 is constituted by patterning an exothermic resistor film 10 on an insulating substrate 9. The part of the element 3 near its supporting section 7 is unevenly distributed on the downstream side of an air flow and a dust adhesion accepting space 11 is secured on the upstream side of the unevenly distributed part by removing the exothermic resistor film. Moisture absorbing dust easily adheres to the space 11 and, by providing the film 10 so as to avoid the space 11, the variation of the heat radiating characteristic of the film 10 against the air is suppressed. It is also possible to suppress the transfer of heat from the film 10 by providing a slit or through hole between the film 10 and space 11.