Design and Computer Control of a Sliding Mode Fuel - Injection Controller for MPI Gasoline Engines

A robust sliding mode control method is proposed for the design of a fuel injection control system, which can maxmize the conversion efficiency of 3-way conversion catalysts. For the purpose of developing and evaluating a fuel-injection controller, the mass of air in the intake manifold and actual fuel flow rate entering the combustion chamber are chosen as state variables of a 4-cycle MPI (Multi-Point Injection) gasoline engines.

On the basis of the simulation results, we have manufactured the ECU (Electronic Control Unit) to operate the MPI gasoline engines and have experimented with 16-bit microprocessor computer. The experimental results show that the sliding mode fuel-injection controller can make the engine operate in the neighborhood of stoichiometric air/fuel ratio (14.7 ± 0.3) and can improve the conversion efficiency of 3-way catalyst more than 90%. Thus, it can satisfy current strict regulations about the automotive exhaust emissions.