Search Results

This paper discusses the possibility of equipping Euro 3 and older vehicles with a universal retrofit kit to reduce the NOX and the PM emissions without producing any secondary effect. Out of several configurations, the optimal setup for EGR and DPF regeneration was evaluated and tested on a passenger car engine testbench. Stationary results showed that with a low pressure EGR it was possible to reduce the NOX emissions by more than 50%, and the filtration efficiency of the DPF was greater than 99%. After various dynamic tests on the test bench to improve the control algorithm, the system was designed to be installed on a garbage truck.

High bandwidth control of the air-fuel ratio is necessary in order to minimize the exhaust emissions of spark-ignition engines with three-way catalytic converters. A new approach is to implement a control structure based on modern control and estimation theory. This work describes the implementation of an estimator-based controller which uses the feedback from an on-off zirconia exhaust oxygen sensor of the type currently used in production vehicles. The limit-cycle associated with the on-off oxygen sensor in conventional systems is eliminated with the estimator-based control structure. Furthermore, the in-cylinder air-fuel ratio tracks the commanded value, so that if a limit cycle is desired in some areas of the engine's operating range for better catalyst operation, its amplitude and frequency can be set arbitrarily.