Estimating Exhaust Manifold Pressure and Temperature via EGR Cooler
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Solution Overview
Problem
Existing systems for internal combustion engines lack effective methods to estimate exhaust manifold parameters without relying on exhaust manifold operation sensors, making it difficult to accurately monitor and manage engine performance.
Innovation Solution
A system that includes an exhaust gas recirculation (EGR) conduit with a cooler and sensors to measure exhaust gas properties, such as pressure and temperature, which are used by a control circuit to estimate exhaust manifold parameters like pressure and temperature, utilizing flow values and sensor signals to calculate these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaust manifold operation sensors are used to directly measure parameters, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses the EGR cooler as an intermediary component to indirectly measure exhaust manifold parameters. By placing temperature and pressure sensors in the EGR cooler inlet and outlet, the system measures temperature drop and pressure differential across the cooler, which serve as proxies for exhaust manifold conditions. This intermediary approach avoids direct sensor placement in the high-temperature, high-pressure exhaust manifold environment.
Solution Approach 2:
The system creates a simplified copy of the exhaust manifold measurement problem by measuring analogous parameters in the EGR cooler. The temperature and pressure conditions in the cooler are correlated to exhaust manifold conditions through established thermal and fluid dynamics relationships, providing an indirect but accurate representation of manifold parameters without requiring direct manifold sensing.
2Reliability
If direct sensors are installed in the exhaust manifold, then reliability of parameter detection is improved, but the system becomes more susceptible to harsh environmental damage
Solution Approach 1:
The EGR cooler serves as a protective intermediary, relocating sensors from the harsh exhaust manifold environment to the more benign cooler environment. The cooler's lower temperature and pressure conditions, along with its condensed exhaust gas, create a far more favorable sensing environment while maintaining measurement reliability through correlated parameter relationships.
Solution Approach 2:
The patent converts the harmful high-temperature, high-pressure exhaust manifold environment into a benefit by using the EGR cooler's cooling and condensation processes. The cooler transforms hot exhaust gas into cooler, condensed vapor, creating ideal sensing conditions. The very process that removes harmful thermal energy from the system provides the beneficial low-temperature environment needed for reliable sensor operation.
3Device complexity
If exhaust manifold parameters are estimated using EGR system parameters, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The system employs feedback relationships between EGR cooler parameters and exhaust manifold parameters. By continuously monitoring temperature drop and pressure differential across the cooler and using these measurements to calculate and update exhaust manifold parameter estimates in real-time, the system maintains high measurement precision through dynamic correlation rather than static assumptions.
Solution Approach 2:
The patent utilizes parameter changes that occur during the exhaust gas cooling and condensation process in the EGR cooler. By measuring how temperature and pressure change as exhaust gas passes through the cooler, the system derives exhaust manifold parameters through established thermodynamic relationships. These parameter transformations provide multiple measurement points that enhance estimation accuracy.
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 estimation of exhaust manifold parameters without direct sensors, improving engine performance monitoring and management by using existing sensors and the EGR system.
Implementation Method 1
a cooler disposed in-line with the EGR conduit and configured to cool exhaust gas flowing therethrough
Data Source
AI summary
A system and method are provided for estimating an operating parameter of an exhaust manifold of an engine. In the system, a flow value is determined that corresponds to a flow rate of exhaust gas through an EGR conduit fluidly coupled between the exhaust manifold and the intake manifold. The EGR conduit includes an exhaust gas cooler disposed in-line with the EGR conduit and a property of the exhaust gas exiting an exhaust gas outlet of the cooler is measured. The operating parameter of the exhaust manifold is estimated as a function of at least the flow value and the property of the exhaust gas exiting the exhaust gas outlet of the cooler. Illustratively, the operating parameter of the exhaust manifold may be exhaust manifold pressure and/or temperature.