Electrically Heated Catalyst Abnormality Detection Using Integrated Energy
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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 differentiate between normal and abnormal conditions, especially at low temperatures.
Innovation Solution
An abnormality detection apparatus that calculates the integrated value of electrical energy supplied over a specific period and compares it to a standard amount, adjusting voltage to maintain target electrical power and detecting abnormalities based on actual energy and energy ratios or changes in energy per unit time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical resistance of the heating element is large at low temperatures, then the heating element can be protected from excessive current, but the electrical power actually supplied to the electrically heated catalyst becomes lower than the standard electrical power, making abnormality detection difficult
Solution Approach 1:
The patent changes the detection parameter from instantaneous electrical power to integrated electrical energy over a specific time period. This allows the system to accumulate enough energy data to make accurate abnormality judgments despite the NTC characteristics causing variable power supply at different temperatures. The controller integrates electrical power over time to obtain electrical energy, which provides a more reliable basis for abnormality detection.
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 becomes large at low temperatures, reducing detection accuracy
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual electrical power supplied to the catalyst and comparing it with the standard electrical power. The controller uses this feedback information to adjust the applied voltage dynamically, ensuring that the electrical power supplied matches the standard value even when NTC characteristics cause initial resistance variations. This feedback mechanism eliminates the need to apply the highest possible voltage from the start.
3Productivity
If the electrical resistance decreases with temperature rise (NTC characteristics), then the heating element becomes more efficient at higher temperatures, but the electrical power actually supplied varies with temperature, complicating abnormality detection
Solution Approach 1:
The patent applies preliminary action by pre-heating the catalyst using the NTC characteristics of the heating element before the catalyst needs to perform its purification function. The controller supplies electrical power to raise the catalyst temperature to the required level, taking advantage of the decreasing resistance with temperature to maintain efficient heating. This preliminary heating action separates the heating function from the detection function, simplifying the overall system.
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 accurate detection of abnormalities in electrically heated catalysts with NTC characteristics by identifying significant differences in electrical energy supplied over time, enhancing preheating performance and reducing 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
AI summary
The controller adjusts a voltage applied to the electrically heated catalyst in such a way as to make the electrical power as the product of the applied voltage and the catalyst current equal to a target electrical power and to apply a voltage substantially equal to a specific upper limit voltage to the electrically heated catalyst when the electrical power that can be supplied to the electrically heated catalyst by applying a voltage equal to or lower than the specific upper limit voltage is lower than the target electrical power. The controller calculates an actually supplied electrical energy defined as the integrated value of the electrical power actually supplied to the electrically heated catalyst over a specific period. The controller determines that the electrically heated catalyst is abnormal if the actually supplied electrical energy is smaller than a specific electrical energy.