PURPOSE: To measure intake air flow rate with good precision by setting a flow meter with arranging a hollow portion of the same in offset position toward an intake air passage wall side to which approaches a part of intake throttle valve above the supporting shaft of the same.
CONSTITUTION: A butterfly type intake throttle valve 3 is provided in a throttle chamber 2 of an intake air passage 1, and above the valve, is provided closely a cylindrical member 21 as a flow rate measuring part of a hot-wire type flow meter provided a hot wire resistor 8 candidly. The center axis a of a hollow portion 21a is nearly parallel to the center axis b of the intake air passage 1. The hollow portion 21a is in a rectangular shape in rectangular section to the center axis of itself and the longitudinal direction of the rectangular shape in section is parallel to the supporting shaft 3b. The center axis a of the hollow portion 21a is offset by a fixed quantity L toward the intake air passage wall 1a side to which approaches a part, above the supporting shaft 3b, of a valve body 3a. When the diameter of the intake air passage 1 is shown in D, L should be in a range of about L/D=0.05W0.15.
MOGI IKUO
NAGASHIMA KAZUAKI
