Estimating Oxygen Storage Capacity in Three-Way Catalysts
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Solution Overview
Problem
Current methods for estimating the oxygen storage capacity of a catalyst in internal combustion engine catalytic converters are inaccurate, limiting fuel savings and emission reduction capabilities, and require additional hardware, which increases costs.
Innovation Solution
A method involving a three-way catalyst observer model, Kalman filter, and kinetic model that estimates oxygen storage capacity using measured inputs like equivalence ratio, fuel flow, and oxygen sensor voltage, linearizes the model, and filters the state to provide an updated capacity estimate, allowing for precise control of engine inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current fuel cut off method during deceleration is used to estimate oxygen storage capacity, then the estimation process is simple, but the estimation accuracy is insufficient to enable aggressive fuel strategy for fuel savings
Solution Approach 1:
The patent replaces the simple mechanical fuel cut-off method with an observer-based estimation system that uses mathematical models (kinetic model, thermal model) and signal processing (Kalman filter) to accurately estimate oxygen storage capacity without requiring additional hardware sensors in the exhaust system.
Solution Approach 2:
The patent introduces an observer model as an intermediary computational layer that processes existing sensor data (oxygen sensor voltage, engine control inputs) through mathematical relationships to derive oxygen storage capacity, rather than directly measuring it or using simple heuristic methods.
2Measurement precision
If additional hardware is added to the engine system to improve oxygen storage capacity estimation, then estimation accuracy improves, but vehicle cost increases
Solution Approach 1:
The patent makes the existing oxygen sensor serve multiple functions: its voltage output is used both for standard fuel control and for the observer-based oxygen storage capacity estimation, eliminating the need for additional dedicated sensors or hardware.
Solution Approach 2:
The system uses the engine's existing control inputs and sensor outputs to self-determine oxygen storage capacity through computational modeling, without requiring external measurement devices or additional hardware infrastructure.
3Measurement precision
If a complex observer model with Kalman filter and kinetic model is used, then oxygen storage capacity estimation accuracy improves, but computational complexity increases
Solution Approach 1:
The patent divides the observer model into distinct functional segments: a kinetic model for chemical reactions, a thermal model for temperature dynamics, and a Kalman filter for optimal state estimation. This modular structure manages computational complexity by organizing calculations into separate, manageable components.
Solution Approach 2:
The patent pre-establishes the mathematical relationships and model structures (kinetic equations, thermal models, filter algorithms) before runtime, allowing the control system to execute predetermined computational procedures with optimized performance rather than performing complex derivations in real-time.
Data Source
AI summary
A method of estimating the oxygen storage capacity of a catalyst includes providing an engine system having an internal combustion engine and an exhaust system having a catalyst and an oxygen sensor, providing a three-way catalyst observer model having a Kalman filter and a three-way catalyst kinetic model, estimating a three-way catalyst next time step state and a modeling error, linearizing the three-way catalyst observer model, filtering the estimated three-way catalyst next time step state, and calculating a covariance.