Patent ID: 6397586
Filing Date: 2002-06-04
Classification: B01D,F01N,F02D

Abstract:
An emission control apparatus for an internal combustion engine, comprising:a catalyst device provided in a main exhaust passage for lessening a harmful gas component of exhaust gas; a bypass passage bypassing a portion of the main exhaust passage that is located upstream of the catalyst device; an adsorbent provided in the bypass passage and that adsorbs an unburned gas component of exhaust gas when the adsorbent has a temperature below a predetermined temperature, and releases the unburned gas component when the adsorbent has a temperature equal to or higher than the predetermined temperature; and a passage switching valve that switches between a first state that causes flow of exhaust gas to the main exhaust passage and a second state that causes flow of exhaust gas to the bypass passage; wherein a flow that occurs through the bypass passage when the passage switching valve is in the first state and the unburned gas component is released from the adsorbent is maintained at an amount that is sufficiently small so that the adsorbent relaease the unburned gas component at a rate that is too small to significantly affect operation of the catalyst device, and wherein the bypass passage includes a first portion in which the exhaust gas flows in a downstream direction with respect to a direction in which the exhaust gas flows through the main exhaust passage, and a second portion in which the exhaust gas flows in an upstream direction with respect to the direction in which the exhaust gas flows through the main exhaust passage, wherein the exhaust gas flows through the first portion prior to flowing through the second portion.