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Evaluation of a Closed Loop Spark Advance Controller Based on a Torque Sensor
Abstract:
A closed loop spark advance control system was evaluated on a Volvo V70 5-cylinder spark ignited engine. The system utilises a crankshaft mounted torque sensor for combustion monitoring which provides individual cylinder combustion phasing information and enables individual cylinder spark advance control. The spark advance control system can compensate for changes in combustion operating conditions and hence limit the need for calibration.
The spark advance control system was used in a mode of cylinder balancing where the control target is to keep the combustion phasing in all cylinders at a defined setpoint. This control law was evaluated in vehicle tests in an emission test chamber, running pre-defined driving cycles FTP72 and Highway Fuel Economy Test. Analysis shows that the combustion phasing was kept close to the selected setpoint during both tests and, hence, robustness in that sense was demonstrated.
The torque ratio concept is used for combustion phasing monitoring based on crankshaft torque measurements. Analysis of the 50% torque ratio as a measure for combustion phasing shows that it is equivalent to 50% burned mass fraction.