Engine exhaust gas purification device

摘要

An upstream catalytic converter (13) and downstream catalytic converter (14) are provided in series in an exhaust passage (12) of an engine (1). The upstream catalytic converter (13) houses a three-way catalyst that becomes active at an activating temperature range between 250 DEG C and 350 DEG C, and the downstream catalytic converters (14, 14A, 14B) house a low temperature NOx trapping catalyst which traps moisture and nitrogen oxides in exhaust gas at a temperature lower than an upper limiting temperature, for example, 200 DEG C. The downstream catalytic converter (14) is separated from the upstream catalytic converter (13) so that the low temperature NOx trapping catalyst has a temperature lower than the upper limiting temperature while the three-way catalyst is in the activating temperature range.