Method for characterizing an air flow within a boosted internal combustion engine

• Main Authors: KERRY D FRANKS, JAMES W YIP, PAUL R ARLAUSKAS, MICHAEL J PRUCKA, DANIEL B DIEBEL, GREGORY L OHL, YI CHENG
• Format: Patent
• Language: English
• Published: 02.07.2003
• Edition: 7
• Subjects: BLASTING; COMBUSTION ENGINES; CONTROLLING COMBUSTION ENGINES; HEATING; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; LIGHTING; MECHANICAL ENGINEERING; WEAPONS

An air mass flow rate target, corresponding to air mass flow rate from the turbo 32 or supercharger 36 is determined from an engine rotational speed 46, throttle position 24, and turbo air bypass position 28. Air flow target, which is the airflow to the inlet manifold 16 is then determined from the air mass flow target and the engine rotational speed. Preferably, look up tables are used for mapping the engine speed and the mass air flow rate target term to obtain a desired torque value. This torque value is corrected in respect to actual operating conditions such as air/fuel ratio or spark advance. The modified torque value is then limited by applying torque limits (72, fig.2) to protect the engine, such limits could be excessive engine speed, exhaust gas temperature, time in boost, engine knock and data for torque converter brake stall, thus generating a total modified desired torque term (70, fig.2) from which the air flow target is determined. The air mass flow rate target may alternatively be determined from a compressibility term based on an air pressure ratio and a reference air mass flow rate term based on throttle position and air bypass valve position.