| 摘要 |
PURPOSE:To improve the knocking detecting accuracy, by generating a reference voltage in response to the output voltage of a filter which is based on the output voltage of a vibration sensor or passes the part other than a specified frequency band of the output signal of the vibration sensor. CONSTITUTION:The output of an amplifier 2 is connected to the filter 3 and an averaging circuit 5. The output of the filter 3 is connected to one input terminal of a comparator 6 through an amplifier 4. The output of the average circuit 5 is connected to the other input terminal of the comparator 6 through an amplifier 7. Since the output signal of the amplifier 2 includes the natural frequency component of an engine itself which is not related to the knocking, its S/N ratio is low. Since the output vibration signal from the amplifier 2 is rectified by the averaging circuit 5 in a half wave rectification mode, the waveform of the output signal of the averaging circuit 5 is smooth. Accordingly, the width of the knocking judging pulses which are generated when the output voltage of the amplifier 4 is larger than the reference voltage obtained by the amplifier 7 becomes the adequate width. Thus, the knocking detecting accuracy can be improved. |
