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Air-to-fuel Ratio Modulation Experiments over a Pd/Rh Three-way Catalyst
Technical Paper
2001-01-3539
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The benefits of deliberately modulating air-to-fuel ratio over a three-way catalyst are disputed. In this work, engine test cell experiments were carried out to assess the performance of a warmed-up Pd/Rh three-way catalyst. The objectives were threefold: first, to determine the best mode of operation; second, to determine if air-to-fuel ratio modulation enhances robustness to transient air-to-fuel ratio disturbances; third, to determine if the conversion efficiency can be manipulated by controlling the shape of the air-to-fuel ratio oscillation. It was observed that the highest conversion efficiency is obtained using a steady air-to-fuel ratio just rich of stoichiometric; however, this mode of operation lacks robustness with respect to transient disturbances and UEGO sensor errors. Robustness can be improved using an oscillating air-to-fuel ratio, but with a sacrifice in peak conversion efficiency. Definite conclusions regarding the benefits of various waveform shapes could not be drawn, but a periodic triangular air-to-fuel ratio input which ramps to the lean slower than it ramps to the rich appears to have superior efficiency than a waveform which ramps to the rich slower than it ramps to the lean.
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Citation
Cornelius, S., Collings, N., Glover, K., and Davison, D., "Air-to-fuel Ratio Modulation Experiments over a Pd/Rh Three-way Catalyst," SAE Technical Paper 2001-01-3539, 2001, https://doi.org/10.4271/2001-01-3539.Also In
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