Detecting a marker in an engine position sensing system.

摘要

An engine position sensing system is of the type in which a toothed wheel 18 having circumferentially spaced marks 24 is mounted on an engine crankshaft 20 with a sensor 12 located adjacent the toothed wheel to detect passing marks 24. The engine rotational position is indicated by a marker 26 on the toothed wheel 18 defined by a missing tooth 24A. The marker 26 is detected by taking the previous, current and subsequent intervals A, B and C respectively between marks 24 and performing an operation thereon in which the current interval B and the previous and subsequent intervals A and C are processed and compared with a constant K according to the formula B<2>/(AxC) >K. Upon detection of the marker 26 an appropriate signal can be generated and sent to an engine management system. K is preferably between 2.6 and 3.5 and typically 3. <IMAGE>