Effect of Phased Air/Fuel Ratio Perturbation and Catalyst O2 Storage Capability on Catalyst Conversion Efficiency

Webb, Cynthia C.; Bykowski, Bruce B.

doi:10.4271/2000-01-2924

Cited by 4 publications

(3 citation statements)

References 5 publications

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“…The first group mainly focuses on the improvement of converter performance through catalyst technology, such as the development of oxygen storage material; improvement of composition and arrangement of precious metals for better conversion efficiency; optimization of the structure to create a catalyst selfregeneration function and mitigate deterioration, etc. The second group includes various activities in engine control, especially in A/F ratio control to increase the performance of the catalyst [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…• The influence of A/F ratio on catalyst light-off time [1,13] • The relationship between forced A/F ratio modulation (frequency and amplitude) and catalyst conversion efficiency [2,3,4,7,8] • The effect of phase-shifted A/F ratio modulation between banks or among cylinders on conversion efficiency [2,3,9] • methods of modeling and measuring the oxygen storage capacity of a catalytic converter by rich-lean transition, A/F ratio sweeping, or other on-line estimation mechanisms [4][5][6][7][10][11][12] We will briefly review the above cases. It is reported that operating an engine with retarded ignition timing combined with lean A/F ratio will decrease catalyst lightoff time and consequently reduce engine emission [1].…”

Section: Introductionmentioning

confidence: 99%

“…For dual bank engines, some research indicates that independently controlling the A/F ratio of each bank to make their lean and rich status just opposite to each other (called phase-shifted A/F ratio modulation) will benefit catalyst efficiency since both rich and lean exhaust species are present simultaneously at the converter and provide a highly reactive mixture to the catalyst [2,3]. It is also claimed that this mechanism will reduce the demand on the oxygen storage capacity of the catalyst since the exhaust from the two banks will combine and achieve a near-stoichiometric mixture prior to entering the converter.…”

Section: Introductionmentioning

confidence: 99%

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Setup of an Engine Rapid Control Prototyping System for Catalyst Research and Evaluation Testing

Jiang

Smith

Furukawa

et al. 2008

SAE Technical Paper Series

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To fulfill ever increasingly stringent emission regulations, a great many studies on engine control and catalytic converter performance have been made. Topics of great interest in this area, to name a few, include: the relationship between catalyst light-off time and air-fuel (A/F) ratio; the relationship between forced A/F ratio modulation and catalyst efficiency; the effects of phaseshifted A/F ratio modulation between banks of a dual bank engine, or among cylinders of a single manifold engine on catalyst efficiency; and methods of modeling and measuring the oxygen storage capacity of a catalytic converter by rich-lean transition, A/F ratio sweeping, or other on-line estimation methods. To undertake this type of research, an engine control system with necessary functions, especially with very flexible A/F ratio control capabilities, is needed. Mass production ECU does not provide the flexibility desired and it is also hard to develop and integrate the control algorithms needed for catalyst testing into the existing ECU software. An engine rapid control prototyping system is set up in an engine dynamometer test cell environment to overcome the limitations of mass production ECU and fulfill the requirements for catalyst research and testing. Model-based development methodology is adopted for the design and implementation of necessary software. Control algorithms, including individual bank control of a dual bank engine, A/F ratio modulation of different frequencies and amplitudes, with and without phase shift between banks, A/F ratio rich-lean transition and sweeping etc, are designed using graphical language, automatically converted into executables to run on the real-time target. UDP communication for real-time command and variable exchange between the engine controller and the test cell controller is developed to facilitate testing. The system provides the flexibility and good control performance desired for catalyst research and evaluation testing. Application and results of the system on a 4.6L V8 gasoline engine is given.

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