Fault Detection and Diagnosis (FDD) on a Knock Sensor

The purpose of this work is Fault Detection and Diagnosis (FDD) on a Knock Sensor because some of the modern petrol engines operate on the efficient four-stroke cycle, where each cylinder of the engine contains an intake and exhaust poppet valve that is operated at the appropriate time. The ECM (Engine Control Module) uses the Knock Sensor signal to control timing. The Knock Sensor detects engine knock and sends voltage signal to the ECM. These signals can be sufficient to detect abnormal combustion, like ‘spark knock’ and ‘surface ignition’. Engine knock occurs within a specified range. The Knock Sensor, located in the engine block, cylinder head, or intake manifold is tuned to detect that frequency, which motivates the use of signal models for detection. But this sensor is a wide-band accelerometer of the piezoelectric type too. Analogy with a general seismic mass system is possible since it is a general damped second order vibrating system which is forced into oscillatory motion. Thus, model-based FDD can be employed too. The purposes of the Knock Sensors for performance and reliability improvements could be missed by its degradation or abnormal behavior. This abnormal behavior could be caused by a fault. Hence, the FDD implemented in the ECM is capable to detect and diagnose these probable faults based on the measurements taken online. The results of the FDD can be used for reconfiguration of the Timing Control System. This work focuses on the FDD development and validation at the test bench.