EXHAUST GAS PURIFICATION APPARATUS

摘要

An exhaust purification apparatus comprising an expansion pipe and a thin catalyst in the exhaust system of an internal combustion engine. Two openings for discharging an exhaust gas are formed in the peripheral wall of the expansion pipe at the end thereof on the upstream side in its longitudinal direction, and center portions of gas-permeable thin catalyst in their transverse direction are disposed separately round the expansion pipe in such a manner as to oppose the openings for the exhaust gas. Both side portions of the thin catalyst are curved towards the expansion pipe and are welded integrally to the outer peripheral surface. The outer periphery of the thin catalyst is sealed by a thin sealing plate as a seal member, and an opening is formed in the sealing plate on the opposite side to the openings for the exhaust gas of the expansion pipe. A communication pipe whose upper end is fitted into the opening of the thin sealing plate penetrates through an opening of a muffler casing which is disposed substantially adjacent to, and in parallel with, the expansion pipe. The lower end of the communication pipe has a U-shaped section which is open towards the downstream side of the muffler casing. According to this construction, the exhaust gas can come into contact with the thin catalyst without being cooled by the expansion pipe or affected by the catalytic reaction heat. Therefore, a purification ratio and scavenging efficiency can be improved, and the size of the purification apparatus can be reduced.