AIR FLOW RATE MEASURING INSTRUMENT AND ENGINE FUEL CONTROL SYSTEM USING IT

摘要

PURPOSE:To obtain a highly accurate heating-resistance type air flow rate measuring instrument for measuring the quantity of intake air of automobile engines by reducing a measurement error caused by a change in shape of an air cleaner and duct provided on the upstream side of the instrument. CONSTITUTION:A main and auxiliary flow passages 2 and 1 are integrally formed in the body 3 of the title instrument and a heating resistance element 4 for detecting flow rate is provided in the auxiliary flow passage 1. The entrance opening 1a of the passage 1 has a plurality of grooves formed on the surface perpendicular to the flow direction of the main flow passage 2 and the groove sections have inclined bottoms and join together on the upstream side of the part 1b of the passage 1 where the heating resistor 4 is installed. Or a plurality of entrances 1a is formed by covering part of the groove-like entrances 1a. Therefore, the measurement error which occurs when the shape of the upstream-side line is changed can be reduced to 1/3 as compared with the conventional example.