| 摘要 |
The duty factor of pulses controlling the time throughout which current flows through an ignition coil is increased or decreased depending upon whether the current through the ignition coil at the last ignition time was less than or greater than the desired amplitude required for ignition. A sample-and-hold circuit samples the output of a comparator comparing the actual current to the desired current at ignition time. If the comparator indicates that the actual current amplitude was less than the desired current amplitude, a first counter is set to count downwards. It counds down by one unit and then its count is transferred to another counter. When the count on the other counter reaches a predetermined count, the current through the ignition coil is initiated. The current is interrupted when either the next ignition timing signal or a signal signifying that the actual current through the ignition coil has reached the desired value is received, whichever is later. In an alternate embodiment, the current is terminated in response to the ignition timing signal, regardless of the then-present value of ignition current. |
