NOx Purification Failure Diagnosis via Exhaust Fuel Injection
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Solution Overview
Problem
Existing systems face challenges in diagnosing the cause of NOX conversion efficiency degradation in vehicle exhaust systems, as it is difficult to determine whether the NOX purification device, oxidizing catalyst, or other components have failed, leading to inefficient diagnostics.
Innovation Solution
An apparatus is developed that includes a diagnosis exhaust-pipe fuel injection control unit, NOX purification device failure specifying unit, oxidizing catalyst device failure specifying unit, and composite failure specifying unit, which perform controlled exhaust-pipe fuel injections and heat generation pattern analysis to determine the cause of NOX conversion efficiency degradation by comparing actual and theoretical heat generation amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NOX conversion efficiency is monitored to detect failures, then failure detection capability is improved, but the ability to identify the specific cause of failure deteriorates
Solution Approach 1:
The diagnostic system segments the exhaust system into multiple functional zones (engine side, exhaust-pipe fuel injector, oxidizing catalyst device, NOX purification device) and performs targeted diagnostics on each segment by controlling fuel injection at specific locations and analyzing temperature changes in corresponding zones, thereby identifying the specific cause of NOX conversion efficiency degradation
Solution Approach 2:
The system uses temperature change as an intermediary parameter to indirectly identify the cause of failure. By monitoring temperature changes in the exhaust gas at different locations during controlled fuel injection, the system can determine which component is malfunctioning without directly measuring the component itself
2Measurement precision
If comprehensive diagnostics are performed to identify the cause of NOX conversion efficiency degradation, then diagnostic precision is improved, but device complexity increases
Solution Approach 1:
The exhaust-pipe fuel injector serves multiple functions: it injects fuel for normal engine operation, injects fuel for diagnostic purposes at different locations (engine side and between catalysts), and its injection amount and timing are controlled by the ECU based on diagnostic requirements. This multi-functionality enables comprehensive diagnostics without adding separate diagnostic injection devices
Solution Approach 2:
The system uses the existing exhaust-pipe fuel injector and ECU control capabilities to perform self-diagnosis. The ECU controls the fuel injection amount and timing based on stored diagnostic programs and analyzes temperature sensor data to automatically identify the cause of NOX conversion efficiency degradation without requiring external diagnostic equipment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise on-board diagnostics to specify the cause of NOX conversion efficiency degradation, allowing for timely identification and classification of failures in engine systems, without requiring additional hardware and through software implementation alone.
Implementation Method 1
an oxidizing catalyst device (210) that promotes oxidation of fuel or intermediate products
Implementation Method 2
exhaust-pipe fuel injection is performed for diagnosis purposes
Data Source
AI summary
An apparatus for on-board diagnoses of causes of NOX conversion efficiency degradation including: a diagnosis exhaust-pipe fuel injection control unit; a NOX purification device failure specifying unit; and an oxidizing catalyst device failure specifying unit.