| 摘要 |
A digital spark timing control for an ignition system of a spark ignited internal combustion engine (10) comprises engine crankshaft position sensing means (14,16) which develops, by way of example, three reference pulses and eighteen position pulses for each complete revolution of the crankshaft (12). The reference pulses (CRANK 2) are angularly spaced by 120 DEG and the position pulses (CRANK 1) by 20 DEG . A spark timing value is computed by computing means (74) and its program is interrupted at the occurrence of a reference or position pulse. The system, at the occurrence of each interrupt, determines whether or not the spark is to occur in the next twenty degree period. If the spark should occur in the next twenty degree period, the system utilizes the most recent twenty degree time period to determine how long it will take the engine crankshaft (12) to rotate from its current position to the desired spark position. This compensates for spark timing errors that might otherwise occur due to changes in engine speed. <IMAGE> |
