Online Estimation of the Oxygen Storage Level of a Three-Way Catalyst 2004-01-0525
Very stringent limits for exhaust gas emissions as well as high claims for onboard diagnosis (OBD) of the three-way catalytic converter (TWC) demand a sophisticated control and observer strategy which can both further reduce the exhaust gas emissions and also estimate the relevant parameters allowing to monitor the decreasing performance of the TWC over its lifetime. The most crucial parameter and state, respectively, are widely believed to be the oxygen storage capacity (OSC) and the relative oxygen level (ROL) of the TWC. The TWC's performance decreases with a diminishing OSC. Therefore, an accurate estimation of the OSC can be used for OBD. Keeping the ROL at an optimal level by means of control enhances the TWC's performance significantly, even during transients of the air/fuel ratio imposed by the driver.
In order to monitor both the ROL and the OSC, an observer has been derived from a complex TWC model. The observer consists of an extended Kalman filter (EKF), which estimates the ROL of the TWC from the exhaust gas mass flow, the temperature and the lambda-sensor signal upstream of the TWC. Additionally, the gas composition and the signal of a sensor downstream are estimated in order to close the loop for the EKF. The EKF also estimates the OSC by means of online estimation.
Citation: Auckenthaler, T., Onder, C., and Geering, H., "Online Estimation of the Oxygen Storage Level of a Three-Way Catalyst," SAE Technical Paper 2004-01-0525, 2004, https://doi.org/10.4271/2004-01-0525. Download Citation
Author(s):
Theophil S. Auckenthaler, Christopher H. Onder, Hans P. Geering
Affiliated:
Swiss Federal Institute of Technology (ETH), Switzerland
Pages: 12
Event:
SAE 2004 World Congress & Exhibition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Electronic Engine Controls 2004-SP-1822
Related Topics:
Three-way catalysts
Catalytic converters
SAE MOBILUS
Subscribers can view annotate, and download all of SAE's content.
Learn More »