Reducing agent supply apparatus abnormality diagnosis unit and reducing agent supply apparatus

Abstract

[Problem] To provide a reducing agent supply apparatus abnormality diagnosis unit that can reduce the limitation on when to perform abnormality diagnosis and on the applicability of abnormality diagnosis to facilitate the implementation of abnormality diagnosis of a reducing agent supply apparatus and to provide the reducing agent supply apparatus.[Means for Resolution] The reducing agent supply apparatus abnormality diagnosis unit includes: a reducing agent injection valve controller for determining an energization on / off duty ratio according to an instructed injection amount of the reducing agent to issue an instruction for driving the reducing agent injection valve; a pump controller for determining an energization on / off duty ratio to issue an instruction for driving the pump so that the pressure in the reducing agent passage is maintained at a predetermined system pressure, based on the difference between the detected pressure in the reducing agent passage and the system pressure; and an abnormality determiner for performing abnormality determination of the reducing agent supply apparatus based on the duty ratio of the reducing agent injection valve and the duty ratio of the pump in a predetermined period.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a reducing agent supply apparatus abnormality diagnosis unit for performing abnormality diagnosis of a reducing agent supply apparatus that injects in an exhaust pipe reducing agent for purifying exhaust gas, and also relates to a reducing agent supply apparatus including the abnormality diagnosis unit.[0002]Conventionally, as one aspect of an exhaust gas purification apparatus for removing nitrogen oxides (hereinafter referred to as “NOx”) contained in exhaust gas from an internal-combustion engine included in a vehicle or the like, an apparatus is practically used which includes: an NOx purification catalyst, provided in the middle of an exhaust passage, for speeding up reduction reaction between NOx and reducing agent; and a reducing agent supply apparatus that injects liquid reducing agent, such as urea aqueous solution and unburnt fuel, upstream of the NOx purification catalyst. The reducing agent supply apparatu...

AI Technical Summary

Benefits of technology

The invention is a method to diagnose abnormalities in a reducing agent supply system used in NOx purification. It involves analyzing the duty ratio of the reducing agent injection valve and pump while maintaining usual injection control. This technology allows for early detection of abnormalities and ensures that the reducing agent supply system operates reliably, ensuring that only the necessary amount of reducing agent is supplied.

Problems solved by technology

However, the apparatus described in JP-A-2008-2426 needs to stop the pump while performing abnormality diagnosis.

So, in order to perform abnormality diagnosis, the apparatus needs to interrupt the usual injection control of reducing agent or needs to perform abnormality diagnosis only when exhaust gas purification control is not performed, which imposes a limitation on when to perform abnormality diagnosis.

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