Exhaust pipe for vehicle-mounted engine

Abstract

An exhaust pipe for a vehicle-mounted engine. An inner pipe inserted in an outer pipe contacts, at its outer end, with the inner peripheral surface of the outer pipe at a first position, the outer pipe contacts the inner pipe at a second position different from the first position, and thus an expansion chamber is formed between the inner pipe the outer pipe. The inner pipe includes a plurality of communication holes for communicating the inside of the inner pipe and the expansion chamber, thereby forming a muffler. An exhaust gas purification catalyst is provided within the outer pipe adjacent to the expansion chamber. On the inner peripheral surface of the outer pipe, a weir for stopping condensed water is provided between the outer end of the inner pipe and the exhaust gas purification catalyst. Consequently, in the exhaust pipe, deterioration of the purification function of the exhaust gas purification catalyst caused by contact of condensed water, which is produced when exhaust gas is cooled, with the exhaust gas purification catalyst can be suppressed.