Catalyst deterioration judging system

Abstract

The deterioration judgment for an absorption reduction type NOx catalyst is performed quickly and correctly. A catalyst deterioration judging system includes a supply unit which supplies a reducing agent, a measuring unit which measures a NOx concentration in an exhaust gas at a position downstream from the catalyst, a control unit which regulates an amount of the reducing agent so that an air-fuel ratio of the exhaust gas is a lean air-fuel ratio when the reducing agent is supplied from the supply unit, and a judging unit which judges deterioration of the catalyst on the basis of the NOx concentration measured by the measuring unit when the amount of the reducing agent is regulated so that the air-fuel ratio of the exhaust gas is the lean air-fuel ratio when NOx is absorbed by the catalyst.

Description

TECHNICAL FIELD[0001]The present invention relates to a catalyst deterioration judging system.BACKGROUND ART[0002]A technique is known, wherein the reduction control is executed for NOx absorbed in an absorption reduction type NOx catalyst (hereinafter simply referred to as “NOx catalyst” as well), and then it is judged that the NOx catalyst is deteriorated if the NOx concentration, which is detected by a NOx sensor disposed on the downstream side from the NOx catalyst, is not less than a predetermined concentration at a point in time at which an estimated value of the absorption amount of NOx in the NOx catalyst arrives at a reference value (see, for example, Patent Document 1).[0003]However, it is necessary to wait until a large amount of NOx is absorbed and stored in the NOx catalyst, and a long time is required to judge the deterioration or degradation of the NOx catalyst. For this reason, if the NOx catalyst is deteriorated or degraded, it is feared that NOx may outflow during ...

AI Technical Summary

Benefits of technology

The patent allows for a quick and accurate way to determine the deterioration of an NOx catalyst. This can help to improve the efficiency of the process and prevent problems down the line.

Problems solved by technology

However, it is necessary to wait until a large amount of NOx is absorbed and stored in the NOx catalyst, and a long time is required to judge the deterioration or degradation of the NOx catalyst.

For this reason, if the NOx catalyst is deteriorated or degraded, it is feared that NOx may outflow during a period until the deterioration judgment is completed.

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