Misfire Detection for Vehicles with Dual Mass Flywheel (DMF) Based on Reconstructed Engine Torque 2007-01-3544
Today, in many passenger cars and light trucks, the conventional driveline is extended by a dual mass flywheel (DMF). The DMF reduces driveline oscillations by mechanically decoupling the crankshaft and the transmission. Existing engine control systems are general designed for use with conventional single mass flywheel (SMF) systems. In the future, to facilitate the optimal control of engines equipped with advanced DMF systems, these conventional control systems may require adaptation, modification or even replacement. In the past, misfire detection has been done by expensive dedicated sensors; seismic, ion current measurement at the spark plugs or even by measuring in-cylinder pressures directly. Typically misfire detection is performed using signals derived from the crankshaft position sensor, which works well for engines with a limited number of cylinders and which are connected to relatively simply drivelines. Torque reactions from the DMF or rest of the driveline can, in extreme circumstances, be misinterpreted as engine misfires, which never actually occurred. Therefore, in this paper, a novel method of misfire detection using the dynamically reconstructed continuous engine torque signal is introduced. Here, the engine torque is estimated by a state space model of the dual mass flywheel. By using the actual reconstructed instantaneous engine torque instead of the commonly used crankshaft acceleration signal, misfire events can be detected far more reliably. Furthermore, if reconstructed engine torque is used as a centrally computed signal for various other purposes (e.g. cylinder balancing control) in the engine management system then the misfire detection system can be easily implemented in the modern engine ECU. This is especially interesting for low to mid-cost vehicles, because it provides a professional solution without the need to install multiple additional sensors to fulfil the increasingly stringent exhaust gas emission laws of the future.