Misfiring identification method by evaluating fluctuations in speed e.g. for combustion engine

摘要

The method involves the use of a timing wheel (2) coupled to the crankshaft of an IC engine (1). The wheel has segments and a sensor monitors the time taken for predetermined segments to pass the sensor. The segment time signals are filtered by two low pass filters (5,6) in parallel the individual output signals of which react at different speeds to changes in their input signals. The difference between the two output signals is determined (7),from which a measure of the changes in the difference is formed. This is compared with a threshold value and if this is exceeded a misfire this is evaluated as a misfire