Exhaust gas purification device for internal combustion engine

Abstract

An auxiliary agent supply means (32, 58) is provided to supply, upstream of an exhaust gas purification means (24, 56, 78), an auxiliary agent for maintaining the exhaust gas purifying function of the exhaust gas purification means (24, 56, 78). A control means (38) for controlling the auxiliary agent supply means (32, 58), thereby regulating the amount of the auxiliary agent supplied includes a standard supply quantity determination section (40, 50, 68, 86) for determining standard supply quantity of the auxiliary agent required to maintain the exhaust gas purifying function, a target supply quantity determination section (42, 52, 70, 88) for determining target supply quantity of the auxiliary agent, by correcting the standard supply quantity on the basis of exhaust pressure, and a supply control section (44, 54, 72, 90) for controlling the auxiliary agent supply means to supply the auxiliary agent in the target supply quantity.

Description

TECHNICAL FIELD[0001]The present invention relates to an exhaust gas purification device for an internal combustion engine, and more specifically, an exhaust gas purification device using an auxiliary agent to maintain an exhaust gas purifying function.BACKGROUND ART[0002]In order to convert pollutants contained in the exhaust gas of an internal combustion engine, such as HC (carbon hydrate), CO (carbon monoxide) and NOx (nitrogen oxides), to purify the exhaust gas, an exhaust gas purification catalyst is conventionally used. In the case of a diesel engine, a particulate filter for trapping particulate matter contained in exhaust is used, in addition to such exhaust gas purification catalyst. In some of exhaust gas purification devices such as exhaust gas purification catalysts and particulate filters, an auxiliary agent is used to maintain their exhaust gas purifying function.[0003]In some particulate filters, when the particulate matter trapped and accumulated in the particulate f...

AI Technical Summary

Benefits of technology

"The present invention provides an exhaust gas purification device for an internal combustion engine that can stably maintain an exhaust gas purifying function by accurately supplying an auxiliary agent required for maintaining the exhaust gas purifying function. The device includes an exhaust gas purification means, an auxiliary agent supply means, a variation factor parameter detection means, and a control means. The control means includes a standard supply quantity determination section, a target supply quantity determination section, and a supply control section. The standard supply quantity of the auxiliary agent is corrected on the basis of the value of the variation factor parameter, and the auxiliary agent is supplied into the exhaust passage in the quantity corrected. This ensures accurate supply of the auxiliary agent in the amount required to maintain the exhaust gas purifying function of the exhaust gas purification means, regardless of the influence of the variation factor."

Problems solved by technology

It is however difficult to directly detect the NOx accumulation quantity.

Thus, fuel in the amount required is not always supplied to the NOx adsorption catalyst, which leads to problems such that NOx is not sufficiently converted into unharmful substances by the NOx adsorption catalyst, that the adsorbed NOx is not sufficiently released so that the purifying capacity of the NOx adsorption catalyst lowers, and that fuel is added excessively so that excess fuel is emitted into the atmosphere.

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