Exhaust Gas Cleaning Catalyst Diagnosis Accuracy at Low Temperatures
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Solution Overview
Problem
The challenge is to accurately diagnose the abnormality of an exhaust gas cleaning catalyst at low temperatures, where assist treatment can incorrectly improve the catalyst's cleaning ability, leading to wrong diagnoses by reducing the difference between normal and abnormal catalyst performance.
Innovation Solution
An internal combustion engine system with a temperature detector and additives supply device that reduces the amount of additives during abnormality diagnosis at low temperatures, and increases them post-diagnosis to improve diagnosis accuracy by distinguishing between normal and abnormal catalysts based on NOx removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If assist treatment is executed by supplying additives to the exhaust gas cleaning catalyst at low temperature, then the ability to clean exhaust gas is improved, but the difference between normal and abnormal catalyst performance is reduced, leading to wrong diagnosis
Solution Approach 1:
The patent applies dynamics by making the additives supply amount variable based on the execution status of abnormality diagnosis. The control device dynamically adjusts the supply amount of additives: when abnormality diagnosis is executed, the supply amount is set to a first (reduced) value to ensure diagnosis accuracy; when abnormality diagnosis is not executed, the supply amount is increased to a second (higher) value to improve exhaust cleaning ability. This dynamic adjustment resolves the contradiction between improving catalyst performance and maintaining diagnosis accuracy.
2Productivity
If the amount of additives is increased to improve catalyst performance at low temperature, then exhaust cleaning ability is enhanced, but diagnosis accuracy deteriorates due to reduced performance difference between normal and abnormal catalysts
Solution Approach 1:
The patent applies parameter changes by modifying the supply amount parameter of additives based on the diagnosis execution status. The control device changes the additives supply parameter from a first value (during diagnosis) to a second value (after diagnosis) to optimize both diagnosis accuracy and exhaust cleaning ability at different operational phases.
3Loss of time
If abnormality diagnosis is executed at low temperature, then early detection is enabled, but wrong diagnosis may occur due to assist treatment masking the abnormality
Solution Approach 1:
The patent applies preliminary anti-action by preemptively reducing the supply amount of additives before executing abnormality diagnosis at low temperature. The control device anticipates the potential masking effect of assist treatment and counteracts it by limiting additives supply during the diagnosis period, thereby preventing wrong diagnosis while enabling early detection.
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
This configuration enhances the accuracy of abnormality diagnosis by increasing the difference in NOx removal rates between normal and abnormal catalysts, preventing incorrect diagnoses and ensuring reliable assessment even at low temperatures.
Implementation Method 1
an exhaust gas cleaning catalyst that is provided in an exhaust passage to clean exhaust gas
Implementation Method 2
a temperature detector that detects a temperature of the exhaust gas cleaning catalyst
Implementation Method 3
an additives-supply device that supplies additives to the exhaust gas cleaning catalyst, the additives being used to improve ability to clean exhaust gas of the exhaust gas cleaning catalyst when the temperature of the exhaust gas cleaning catalyst is not more than a predetermined temperature
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An internal combustion engine (1) includes an electronic control unit (10) configured to supply additives to an exhaust gas cleaning catalyst (3, 30) having a temperature not more than a predetermined temperature. The electronic control unit (10) executes abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) based on ability to clean exhaust gas of the exhaust gas cleaning catalyst (3,30). When preforming abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) at a temperature not more than the predetermined temperature, the electronic control unit (10) reduces the amount of the additives to be supplied to the exhaust gas cleaning catalyst (3, 30) to less than the amount thereof when abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) at a temperature not more than the predetermined temperature is not executed.