| 摘要 |
PROBLEM TO BE SOLVED: To restrict the lowering of SOx emission control effect by supplying a SOx reducing agent at a high temperature of the catalyst when emitting SOx, giving consideration to reduction of the SOx reducing agent due to agitation by a turbo supercharger. SOLUTION: When controlling the sulfur poisoning recovery, the nearly same fuel is used for injection in a compression stroke and an expansion stroke, and operation is performed at a theoretical air-fuel ratio to raise the temperature of a NOx trap catalyst to about 650 deg.C in early time. When the catalyst reaches a desirable temperature, a fuel rate in the compression stroke is increased in relation to the fuel in the expansion stroke, and while the air-fuel ratio is changed to rich to lower the oxygen thickness in the exhaust gas and restrict the agitating effect, and HC necessary for reduction of sulfur is supplied.
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