| 摘要 |
PURPOSE:To improve the detecting accuracy of knocking by a method wherein a knocking signal, received half-wave rectification by a background voltage higher than a predetermined voltage, is clamped when the feedback control of ignition timing is effected in accordance with the strength of knocking. CONSTITUTION:The signal of a knocking sensor 100 is inputted into an amplifier 201, provided with an ignition noise cut circuit 202 having a gate for cutting an ignition noise, and is amplified. Thereafter, the signal is inputted into a band pass filter 204 in order to detect the knocking signal only. The signal from the band pass filter 204 receives the half-wave rectification by a half-wave rectifying circuit 205 and, thereafter, is converted into a background level by a background level detecting circuit 207. In case the knocking signal is very large, the background voltage is changed. In order to prevent the change, the knocking signal is clamped by a knocking signal clamping circuit 206. According to this method, the detecting accuracy of knocking may be improved.
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