BOOST LIMITATION IN A TORQUE BASED ENGINE MANAGEMENT SYSTEM

Turbo charged engines are gaining increasing interest for downsizing and improved fuel economy. In a modern torque based engine management system (EMS) the turbo engine provides a special challenge in estimation of maximum available torque. For the naturally aspirated engine the available torque is more or less proportional to the density of the atmosphere, however, the turbo charged engine has a more complicated relation between atmospheric conditions and maximum available torque. This paper presents a method to calculate, in real time, the reachable boost pressure with respect to turbo rotor speed and temperature after compressor. This maximum boost pressure can then be used in the EMS torque model to estimate maximum available torque.