EHC Abnormality Detection Using Temperature-Adaptive Energy Thresholds
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Solution Overview
Problem
The accuracy of abnormality detection in electrically heated catalysts with NTC characteristics is compromised due to temperature-dependent electrical resistance, making it difficult to distinguish between normal and abnormal conditions using a constant criterion, especially at low temperatures.
Innovation Solution
An abnormality detection apparatus that adjusts the threshold for electrical energy comparison based on the temperature of the electrically heated catalyst at the time of power supply, using a ratio of actually supplied energy to target energy, allowing for accurate detection irrespective of temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant threshold is used for comparing actual electrical power with standard electrical power, then the detection method is simple, but the detection accuracy deteriorates at low temperatures due to NTC characteristics
Solution Approach 1:
The patent applies dynamics by making the threshold dynamic instead of constant. The threshold is adjusted based on the initial temperature of the electrically heated catalyst, allowing the detection system to adapt to temperature variations. This resolves the contradiction by maintaining detection accuracy across different temperatures while keeping the system relatively simple through automated temperature-based threshold selection.
Solution Approach 2:
The patent changes the threshold parameter based on temperature conditions. By establishing different threshold values corresponding to different initial temperature ranges, the system accounts for the NTC characteristics of the heating element. This parameter change approach maintains high detection accuracy without requiring complex real-time calculations during operation.
2Power
If the highest possible voltage is applied to the electrically heated catalyst, then the electrical power supply is maximized, but the difference between actual and standard electrical power increases at low temperatures even when normal
Solution Approach 1:
The patent changes the evaluation parameter from absolute power difference to a ratio-based assessment. By comparing actual electrical power to standard electrical power as a ratio rather than an absolute difference, and by adjusting the threshold based on initial temperature, the system can evaluate performance accurately even when high voltage is applied and large absolute differences occur due to NTC characteristics.
3Measurement precision
If the threshold is adjusted according to temperature, then the detection accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing multiple threshold values corresponding to different temperature ranges before operation. The system measures the initial temperature and selects the appropriate threshold from predetermined options, avoiding the need for complex real-time threshold calculation algorithms. This maintains detection accuracy while keeping the implementation relatively simple.
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 high-accuracy detection of abnormalities in electrically heated catalysts with NTC characteristics by dynamically setting the threshold according to the initial temperature, ensuring effective preheating and reduced exhaust emissions.
Implementation Method 1
a heating element that generates heat when supplied with electrical power
Implementation Method 2
the base material of the heating element of the electrically heated catalyst is a material whose electrical resistance decreases with rise of temperature (namely, a material having NTC characteristics)
Data Source
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AI summary
An abnormality detection apparatus calculates an actually supplied electrical energy defined as the integrated value of electrical power actually supplied to the electrically heated catalyst over a specific period from the time when the supply of electrical power to the electrically heated catalyst is started and a target electrical energy in the specific period, and further calculates, from these integrated values, an accomplishment parameter relating to the ratio of the actually supplied electrical energy to the target electrical energy. The abnormality detection apparatus detects an abnormality of the electrically heated catalyst by comparing the accomplishment parameter with a specific threshold. The abnormality detection apparatus is configured to set the specific threshold according to the temperature of the electrically heated catalyst at the time when the supply of electrical power is started.