Exhaust Purification Device of Compression Ignition Type Internal Combustion Engine

Abstract

In an internal combustion engine, the engine is formed so that an output of an electric motor can be superposed on an output of the engine. In the engine exhaust passage upstream of the NOX storage catalyst, an SOX trap catalyst able to trap the SOX contained in the exhaust gas is arranged. When regenerating the SOX trap catalyst, the vehicle drive power from the engine and the vehicle drive power from the electric motor are adjusted so that the SOX concentration in the exhaust gas flowing out from the SOX trap catalyst becomes less than a predetermined SOX concentration during the regeneration period.

Description

TECHNICAL FIELD[0001]The present invention relates to an exhaust purification device of a compression ignition type internal combustion engine.BACKGROUND ART[0002]Known in the art is an internal combustion engine arranging in an engine exhaust passage an NOX storage catalyst storing NOX contained in exhaust gas when the air-fuel ratio of the inflowing exhaust gas is lean and releasing the stored NOX when the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich. In this internal combustion engine, NOX formed when burning fuel under a lean air-fuel ratio is stored in the NOX storage catalyst. On the other hand, as the NOX storage catalyst approaches saturation of the NOX storage ability, the air-fuel ratio of the exhaust gas is temporarily made rich, whereby NOX is released from the NOX storage catalyst and reduced.[0003]However, fuel and lubrication oil contain sulfur. Therefore, the exhaust gas also contains SOX. This SOX is stored together wit...

AI Technical Summary

Benefits of technology

[0008]An object of the present invention is to provide a compression ignition type internal combustion engine able to hold the SOX concentration in the exhaust gas flowing out from the SOX trap catalyst at a certain limit or lower.

Problems solved by technology

However, fuel and lubrication oil contain sulfur.

However, even when using such an SOX trap catalyst, when the SOX trap rate of the SOX trap catalyst falls, it is necessary to regenerate the SOX trap catalyst.

However, the amount of SOX trapped by this SOX trap catalyst is much greater than the amount of SOX stored in the NOX storage catalyst, and thus, if the SOX trap catalyst is excessively raised in temperature even a little, the trapped SOX is released all at once.

As a result, the SOX concentration in the exhaust gas flowing out from the SOX trap catalyst ends up becoming extremely high.

SOX is itself harmful, and if the temperature becomes higher, SOX sometimes changes to harmful hydrogen sulfide H2S.

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