Exhaust system affecting suction of secondary air by use of larger connector pipe

摘要

An exhaust line including an exhaust pipe assembly, a reactor for oxidizing hydrocarbons and carbon monoxide, a main muffler and a mechanism for drawing secondary air from the atmosphere into the exhaust line upstream of the reactor based on the pulsation of the exhaust pressure, wherein a front tube of the exhaust pipe assembly for passing the exhaust gas from the engine to the reactor has a smaller cross-sectional area than a center tube connecting the reactor to the main muffler, so that the pulsation is of a great magnitude even at an engine speed where the pulsation is in an anti-resonance state.