Patent ID: 6823664
Filing Date: 2004-11-30
Classification: B01D,F01N,F02D

Abstract:
An exhaust gas purification device comprising:a NOx absorbent which is disposed in an exhaust gas passage through which exhaust gas discharged from an internal combustion engine passes, this NOx absorbent absorbing NOx when an air-fuel ratio of inflowing exhaust gas is lean, and reducing and purifying the absorbed NOx when the air-fuel ratio of the inflowing exhaust gas becomes richer; an exhaust gas flow rate control portion for controlling a flow rate of the exhaust gas flowing to the NOx absorbent; a reductant addition portion for adding reductant into the exhaust gas passage upstream of the NOx absorbent; a temperature rise control portion for controlling a temperature of the NOx absorbent such that the temperature is higher than a predetermined temperature; a rich condition control portion for controlling the air-fuel ratio of the exhaust gas flowing to the NOx absorbent such that one of a substantially stoichiometric condition and a rich condition is formed; a sulfur poisoning regeneration control portion for discharging sulfur components from the NOx absorbing portion, by executing control of the temperature rise control portion and the rich condition control portion in succession, and furthermore, executing control of the exhaust gas flow rate control portion such that the flow rate of the exhaust gas flowing to the NOx absorbent is less during execution of control of the rich condition control portion than during execution of control of the temperature rise control portion; and a by-pass passage that by-passes the NOx absorbent, wherein: the exhaust gas flow rate control portion controls both the flow rate of the exhaust gas flowing to the NOx absorbent, and the flow rate of the exhaust gas which by-passes the NOx absorbent.