Electrically Heated Catalyst Temperature Determination
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Solution Overview
Problem
Existing methods for determining the component temperature of electrically heatable catalytic converters in internal combustion engine exhaust systems are prone to inaccuracies due to environmental influences, especially when the catalytic converter is positioned far from the engine outlet, leading to insufficient modeling of exhaust gas temperature and deviations from the actual component temperature.
Innovation Solution
A method that determines the component temperature of an electrically heatable catalytic converter by measuring the temperature-dependent electrical resistance of a heating resistor, which is energized through a switch connecting the vehicle's battery, using known current and voltage values, allowing for precise temperature determination without additional temperature sensors and accounting for aging effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to determine component temperature, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The heating resistor serves dual functions: heating the catalytic converter and acting as a temperature sensor through its temperature-dependent resistance. This self-service approach eliminates the need for separate temperature sensors, reducing device complexity while maintaining measurement capability
Solution Approach 2:
The heating resistor is designed to perform multiple functions: electrical heating of the catalytic converter and temperature measurement through resistance monitoring. This multi-functionality reduces the number of components needed in the system
2Device complexity
If model-based temperature determination is used, then device complexity is reduced, but measurement precision deteriorates due to environmental influences
Solution Approach 1:
The heating resistor provides direct temperature information through its resistance value, eliminating the need for complex environmental modeling. The resistance directly reflects the actual component temperature without requiring calculations based on exhaust gas temperature and environmental factors
Solution Approach 2:
The patent replaces complex thermal modeling and calculation systems with a direct electrical measurement approach. Instead of using mathematical models to estimate temperature from multiple parameters, the system directly measures temperature through the electrical resistance of the heating resistor
3Measurement precision
If heating resistor is continuously energized for temperature measurement, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The heating resistor is energized periodically in measurement cycles rather than continuously. During these brief measurement intervals, sufficient current is applied to obtain accurate resistance measurements, then the heating is reduced or stopped, minimizing overall energy consumption while maintaining measurement capability
Solution Approach 2:
The system applies partial heating action during measurement cycles - enough current to obtain accurate resistance measurements but less than what would be required for full heating operation. This partial action achieves the measurement goal with minimal energy expenditure
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 method enables precise and energy-efficient determination of the catalytic converter's temperature, reducing environmental influence errors and improving measurement accuracy, thereby enhancing the conversion performance and durability of the catalytic converter.
Implementation Method 1
the catalytic converter can be heated by an electric heating element independently of the exhaust gas flow
Implementation Method 2
the heating resistance of an electrically heatable catalytic converter is generally highly dependent on the component temperature and increases with increasing component temperature at the same current intensity
Data Source
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AI summary
The invention relates to a method for determining the temperature of an electrically heated catalyst (24, 28). The electrically heated catalyst (24, 28) has an electrical heating element with a heating resistor (48), the electrical resistance of which changes depending on the component temperature of the electrically heated catalyst (24, 28). This resistance is determined from the current (I) and the voltage (U) across the electrically heated catalyst (24, 28), and the component temperature of the catalyst (24, 28) is then determined based on a characteristic curve stored in the control unit (40). The heating resistor (48) is only energized for a short time to determine the component temperature, in order to minimize the energy input into the heating resistor and thus prevent it from overheating.Furthermore, the short time interval is intended to minimize the energy required for determining the component temperature of the electrically heated catalyst (24, 28).