Catalyst Deterioration Diagnosis Using Hydrocarbon Gas Sensors
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Solution Overview
Problem
Current methods for diagnosing the deterioration of oxidation catalysts in diesel engine exhaust systems, particularly in oxygen-excessive atmospheres, face challenges due to inaccurate measurement accuracy and indirect diagnosis techniques, leading to errors and poor fuel economy.
Innovation Solution
A method involving a hydrocarbon gas sensor placed downstream of the oxidation catalyst in the exhaust path to directly measure the concentration of unburned hydrocarbon gases, comparing it with pre-defined threshold values based on catalyst temperature, allowing for real-time and accurate diagnosis of catalyst deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature difference measurement method is used to diagnose oxidation catalyst deterioration, then diagnosis can be performed indirectly, but measurement accuracy is poor due to large errors from exhaust gas temperature and flow rate changes
Solution Approach 1:
The patent replaces indirect thermal measurement methods with direct chemical concentration measurement using a hydrocarbon gas sensor. Instead of measuring temperature differences to infer catalyst performance, the system directly detects unburned hydrocarbon concentration in the exhaust gas, providing accurate real-time data on oxidation catalyst efficiency without being affected by exhaust gas temperature and flow rate variations.
2Reliability
If fuel injection is used to accelerate heat generation for diagnosis, then catalyst conversion capability can be assessed, but fuel economy deteriorates due to large fuel injection amount
Solution Approach 1:
The patent utilizes the existing unburned hydrocarbon gases present in the diesel engine exhaust as the diagnostic test substance, eliminating the need for additional fuel injection. The hydrocarbon gas sensor directly measures these naturally occurring emissions to assess catalyst performance, thereby achieving accurate diagnosis without any additional fuel consumption.
3Reliability
If wide range oxygen concentration sensors are used to measure oxygen consumption, then catalyst conversion capability can be indirectly diagnosed, but measurement accuracy is insufficient due to small oxygen consumption amounts in O2-excessive atmosphere
Solution Approach 1:
The patent changes the measurement parameter from oxygen consumption (which is too small to measure accurately in O2-excessive atmosphere) to unburned hydrocarbon concentration. By measuring the concentration of hydrocarbon gases that the oxidation catalyst is designed to convert, the system achieves accurate diagnosis of catalyst performance with a measurement parameter that is readily detectable even in oxygen-rich exhaust conditions.
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 approach enables precise and timely diagnosis of oxidation catalyst deterioration, improving diagnostic accuracy and reducing fuel consumption by directly measuring unburned hydrocarbon concentrations, thus enhancing engine performance and compliance with environmental standards.
Implementation Method 1
a hydrocarbon gas sensor placed downstream of the oxidation catalyst in the exhaust path to directly measure the concentration of unburned hydrocarbon gases
Implementation Method 2
an oxidation catalyst for a diesel engine... oxidizing or adsorbing an unburned hydrocarbon gas
Data Source
Figure 1
Figure 2A~2B
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AI summary
A method for diagnosing the degree of deterioration of a catalyst disposed in an exhaust path of an internal combustion engine and oxidizes or adsorbs a target gas, including at least one of a hydrocarbon gas and a carbon monoxide gas, in an exhaust gas from the internal combustion engine, is adapted to determine whether deterioration exceeding an acceptable level of a catalyst occurs or not by comparing, at any timing when the internal combustion engine is in a state of a steady operation, the concentration of a target gas detected downstream from the catalyst in the exhaust path with a threshold value of the concentration of a target gas corresponding to the temperature of a catalyst at the timing which is previously defined according to an allowable range of an index value representing the degree of oxidation or adsorption at the catalyst corresponding to the temperature of a catalyst at the timing.