An Algorithm for the Calibration of Wall-Wetting Model Parameters

Alessandro di Gaeta; Stefania Santini; Luigi Glielmo; Ferdinando De Cristofaro; Carlo Di Giuseppe; Antonello Caraceni

doi:10.4271/2003-01-1054

2003-03-03

An Algorithm for the Calibration of Wall-Wetting Model Parameters 2003-01-1054

Spark-ignited engines equipped by a three-way catalyst require a precise control of the air fuel ratio fed to the combustion chamber. A stoichiometric mixture is necessary for the proper working of the catalyst in order to meet the legislation requirement.

A critical part of the air fuel ratio control is the feed-forward compensation of the fuel dynamics. Conventional strategies are based on a simplified model of the wall-wetting phenomena whose parameters are stored in off-line computed look-up tables. Unfortunately, errors in the parameters calibration over the whole engine map deteriorate the control performances in terms of emissions.

In this paper an automatic procedure for a rapid and efficient identification of the wall-wetting parameters is presented. The whole procedure has been experimentally tested on a vehicle by using a test bench. Using the identified parameters values, a significant reduction in the air fuel ratio excursion has been achieved during rapid throttle transients with respect to the same vehicle equipped by a commercial ECU with resident engine maps computed by traditional calibration activity. Moreover, the algorithm can be also on-line used to improve air-fuel ratio control performances.

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An Algorithm for the Calibration of Wall-Wetting Model Parameters 2003-01-1054

SAE MOBILUS