Search Results

An accurate air flow rate model is critical for high-quality air-fuel ratio control in Spark-Ignition engines using a Three-Way-Catalyst. Emerging Variable Valve Timing technology complicates cylinder air charge estimation by increasing the number of independent variables. In our previous study (SAE 2004-01-3054), an Artificial Neural Network (ANN) has been used successfully to represent the air flow rate as a function of four independent variables: intake camshaft position, exhaust camshaft position, engine speed and intake manifold pressure. However, in more general terms the air flow rate also depends on ambient temperature and pressure, the latter being largely a function of altitude. With arbitrary cam phasing combinations, the ambient pressure effects in particular can be very complex. In this study, we propose using a separate neural network to compensate the effects of altitude on the air flow rate.

Turbocharging and intercooling were applied to a 1.1 1 passenger car gasoline engine in order to achieve power and torque of a 1.6 1 naturally aspirated engine. On the basis of standard production four cylinder OHC powerplant a prototype engine was developed featuring: turbocharger with integral wastegate, intercooler, pressurised carburettor and modified camshaft. Extensive dynamometer testing was carried out with the main objective to investigate effects of various design parameters on turbocharger system behaviour and to select optimum values for a desired power increase. Following parameters were varied: boost pressure level, temperature and pressure drop across intercooler, turbine housings and valve timing. Fuel economy comparison shows that turbocharged engine can be advantageous in the low load - low speed region.