Exhaust gas purification device for an internal combustion engine
First Claim
1. An exhaust gas purification device for a compression-firing internal combustion engine having a direct cylinder fuel injection valve which injects fuel directly into a combustion chamber, said exhaust gas purification device comprising:
- a NOx absorbent which is disposed in an exhaust gas passage of an engine, and which absorbs NOx in an inflowing exhaust gas when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent is lean and releases absorbed NOx when the oxygen concentration of the inflowing exhaust gas is lowered;
excess air ratio reducing means for reducing the excess air ratio of the engine when the NOx absorbent is to release the absorbed NOx, thereby reducing the oxygen concentration of the exhaust gas flowing into the NOx absorbent; and
combustion control means for controlling combustion of the engine, when the excess air ratio reducing means reduces the excess air ratio of the engine, in such a manner that the amount of the fuel injected from the direct cylinder fuel injection valve which contributes to pre-mixture fuel combustion in the combustion chamber is increased with respect to the amount of the fuel injected from the fuel injection valve which contributes to diffusive combustion in the combustion chamber.
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Accused Products
Abstract
In the exhaust gas purification device of the present invention, a NOx absorbent is disposed in the exhaust gas passage of a diesel engine. At the time when NOx should be released from the NOx absorbent, a control circuit of the engine reduces the excess air ratio of the engine, and switches the combustion mode of the engine from the normal diesel combustion, in which diffusive combustion is dominant in the combustion chamber of the engine, to the combustion mode in which pre-mixture fuel combustion is dominant. By doing this, it is possible, even in a diesel engine, to reduce the excess air ratio in combustion to thereby make the air-fuel ratio of the exhaust gas lower than or equal to the stoichiometric. Thus, the regeneration of the NOx absorbent can be performed even when it is applied to a diesel engine.
141 Citations
21 Claims
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1. An exhaust gas purification device for a compression-firing internal combustion engine having a direct cylinder fuel injection valve which injects fuel directly into a combustion chamber, said exhaust gas purification device comprising:
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a NOx absorbent which is disposed in an exhaust gas passage of an engine, and which absorbs NOx in an inflowing exhaust gas when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent is lean and releases absorbed NOx when the oxygen concentration of the inflowing exhaust gas is lowered; excess air ratio reducing means for reducing the excess air ratio of the engine when the NOx absorbent is to release the absorbed NOx, thereby reducing the oxygen concentration of the exhaust gas flowing into the NOx absorbent; and combustion control means for controlling combustion of the engine, when the excess air ratio reducing means reduces the excess air ratio of the engine, in such a manner that the amount of the fuel injected from the direct cylinder fuel injection valve which contributes to pre-mixture fuel combustion in the combustion chamber is increased with respect to the amount of the fuel injected from the fuel injection valve which contributes to diffusive combustion in the combustion chamber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification