Electrically Heated Catalyst Abnormality Detection
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Solution Overview
Problem
Existing abnormality detection methods for electrically heated catalysts in internal combustion engines are inaccurate due to the failure to consider changes in insulation resistance caused by condensed water, leading to potential misdiagnosis of catalyst abnormalities.
Innovation Solution
An abnormality detection apparatus that includes a heat generation element and an insulation part, where the determination unit assesses the insulation resistance after a predetermined period to detect abnormalities, with threshold values adjusted based on engine temperature, insulation resistance, and electric energy supplied, to differentiate between normal and abnormal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If insulation resistance is measured to detect catalyst abnormalities, then abnormality detection is performed, but detection accuracy deteriorates due to condensed water changing insulation resistance values
Solution Approach 1:
The system performs preliminary heating of the catalyst before measuring insulation resistance. By activating the heating element beforehand to raise the catalyst temperature above the dew point, condensed water is prevented from forming on the insulation part, ensuring accurate insulation resistance measurements that reliably indicate actual catalyst abnormalities rather than moisture interference.
Solution Approach 2:
The system changes the temperature parameter of the catalyst by applying heat before measurement. This temperature change transforms the environment from a condensation-prone state to a condensation-free state, thereby stabilizing the insulation resistance value and improving both measurement precision and reliability for abnormality detection.
2Temperature
If the catalyst is heated before engine start, then temperature rise is achieved, but condensed water may still form if heating is insufficient
Solution Approach 1:
The system applies preliminary heating action to the catalyst before engine operation to preemptively counteract the condensation problem. By raising the catalyst temperature above the dew point of exhaust gases beforehand, the system prevents condensed water from forming on the insulation part during subsequent insulation resistance measurements, eliminating the harmful effect of moisture interference.
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
Enhances the accuracy of abnormality detection in electrically heated catalysts by correlating insulation resistance changes with condensed water generation, improving the reliability of diagnosing issues such as temperature rise failures or electrical faults.
Implementation Method 1
a heat generation element that is arranged in an exhaust passage of an internal combustion engine, and generates heat by electrical energization thereof
Implementation Method 2
an insulation part that provides electrical insulation so as to prevent electricity from flowing through said exhaust passage when said heat generation element is electrically energized
Implementation Method 3
when an internal combustion engine is started in a state where the temperature of an electrically heated catalyst is not high enough, water or moisture may condense in an electrically heated catalyst
Data Source
AI summary
Abnormality of an electrically heated catalyst is detected in a more accurate manner. In an abnormality detection apparatus for an electrically heated catalyst which is provided with a heat generation element that is arranged in an exhaust passage of an internal combustion engine, and is electrically energized to generate heat, and an insulation part that provides electrical insulation so that electricity does not flow through the exhaust passage when the heat generation element is electrically energized, provision is made for a determination unit which makes a determination that abnormality has occurred in the electrically heating catalyst, in cases where the heat generation element is electrically energized from before starting of the internal combustion engine, and in cases where a value of an insulation resistance of the insulation part after a predetermined period of time has elapsed from the starting of the internal combustion engine is equal to or less than a threshold value.