AIR FLOW RATE MEASURING UNIT INTEGRATED WITH THROTTLE BODY

摘要

PROBLEM TO BE SOLVED: To enhance the measurement accuracy by providing a protrusion in the upstream of the outlet of a sub-air path so that the air flow from the outlet of the sub-air path is insusceptible to the resistance of air flow in a main air circuit. SOLUTION: The air flow rate measuring unit 4 integrated with throttle body being employed for controlling an internal combustion engine comprises a heating element 8 for measuring the air flow rate disposed in a sub-air passage 2 arranged in a main air passage 3 and delivers a flow rate signal to a control unit. The sub-air passage 2 has a bypass structure comprising a sub-air passage inlet 2a opening substantially perpendicular to the air flow 14 in the main air passage 3, and a sub-air passage outlet 2b opening substantially horizontally. A protrusion 1a is provided in the upstream of the outlet 2b to open the downstream and one side face thereof. The air flow in the sub-air passage 2 joins the air flow 14 in same direction because of the protrusion and the current velocity is quickened and stabilized thus producing a correct air flow rate signal.