Detecting pre-ignition in internal combustion engines, makes successive comparisons of measured changes in angular displacements of cam- or crank shaft during working cycle

摘要

The internal combustion engine has an external ignition system. Angular displacements of the crank- or cam shaft are picked up from an encoder or sensor wheel. Successive comparisons of detected values are used to identify pre-ignition. Maximum values of angular velocity departures are determined within a region of the working cycle. From these, sliding medians are determined and compared over the working cycle. When the maximum measured variation exceeds given departures from these values, pre-ignition is identified.