EXHAUST EMISSION CONTROL DEVICE

摘要

PROBLEM TO BE SOLVED: To solve a problem that HC easily emitted after starting is not fully purified because HC absorption starts from a HC absorption material before a three-way conversion catalyst reaches an active temperature in an exhaust emission control device using the HC absorption material.

SOLUTION: A slit is formed to traverse a cell in a honeycomb-type carrier of a HC trap catalyst 9 located in an upstream side out of a plurality of HC tray catalysts 9.10. Rising in temperature and absorption timing are delayed as a whole of a catalyst carrier because heat transfer into a downstream side is suppressed more than the slit owing to that the slit has action for masking the heat transfer in the carrier before and after. Process efficiency at HC absorption is also improved because a degree of conversion is improved owing a rise in temperature in a catalyst metal during this period. Even if absorbed HC not sufficiently treated by an upstream side HC trap catalyst is produced, it can be securely purified with a downstream side HC trap catalyst.

COPYRIGHT: (C)2004,JPO