Ignition system with ion current detecting circuit

摘要

An ignition system with an ion current detecting circuit has an ignition circuit and an ion current detecting circuit. The ignition circuit has an ignition coil that has relatively low inductance about less than 10 henries (H), and a driving circuit for a multi-spark ignition sequence. The ion current detecting circuit detects a second harmonic component of the knock. The components of the system are designed so that a resonance frequency of an ion current path substantially coincide with the second harmonic frequency, and so that a Q-value of the ion current path is greater than 1. As a result, it is possible to improve a knock detecting accuracy.