PURPOSE: To provide a highly accurate and reliable air flow rate measuring equipment by suppressing the measurement error when the pulsation of air in the suction system of the internal-combustion engine of an automobile is accelerated to produce a counter flow.
CONSTITUTION: The outlet of a sub-air passage 4 is opened in the direction substantially perpendicular to the main flow of a main air passage 3 or in the obliquely downward direction. The structural member of the passage is provided with inclining faces in the upstream side and downstream side of the outlet in order to eliminate a plane normal to the main stream against which the counter flow strikes directly. Consequently, local increase of dynamic pressure due to the counter flow in the vicinity of the outlet of the sub-air passage 4 is avoided thus reducing the counter flow in the sub-air passage 4. This constitution reduces the output error of an air flow rate measuring equipment by a factor of 2 or 3 as compared with a conventional equipment when a counter flow is generated in the main air passage 3 due to pulsation of the suction system.
KOBAYASHI CHIHIRO
IGARASHI SHINYA
TSUTSUI MITSUKUNI
MIYAZAKI ATSUSHI
SUEMATSU HIROYUKI
AKAGI YOSHIHIKO
HITACHI AUTOMOTIVE ENG