Abstract
Keywords
HFM (Hot film Flow Meter), USFM (Ultra Sonic Flow Meter), LFM (Laminar Flow Meter), Reverse flow, Flow fluctuation
Abstract
In current spark ignition engines, the air fuel ratio is usually controlled by ECU (Electronic Control Unit) and variable sensor signals contribute to ECU for feedback control. Because HFM (Hot film Flow Meter) offers a primary data of air mass flow rate to ECU, the measurement errors of HFM deteriorate the engine performance (e.g., volumetric efficiency, exhaust emission). The heat capacity of HFM as well as the characteristic of the gas exchange processes (e.g., fluctuation, reverse flow, velocity distribution in the cross-sectional area of air duct) causes the measurement errors of HFM. Thus, the reduction of HFM measurement errors contributes to the feedback control of the electronic fuel injection system. To reduce the measurement errors of HFM, this study investigated the effect of intake system geometry (e.g., intake duct length & angle, Helmholtz resonator geometry)