AIR FUEL MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To measure air flow at low cost and with high accuracy by forming a duct in such a way that cross-sectional area vertical to the air flow direction of a connecting part in a duct part is a minimum cross-sectional area part of the duct part for installing an air meter. SOLUTION: Intake air passes an air cleaner element 3 from an air cleaner inlet part and passes a main air passage 5 of a duct part 2 and an auxiliary air passage 6 installed at a circuit module part so as to be supplied to an engine. The duct 2 for installing an air flow measuring device is so formed that the cross-sectional area of a part 4 connected to an air cleaner case 1 is the smallest in the duct 2. Since the duct connecting part 4 is completely surrounded by the air cleaner case 1, thermal contraction, drawback, and the like after molding are small compared to a normal pipeline, and dimensional accuracy after molding is high. The air flow measuring device of low cost and high accuracy can thereby be obtained, and parts such as an air passage body can be cut down so as to reduce an installation space in an engine room.