| 摘要 |
PURPOSE:To detect the knocking, a pressure peak value, etc., in a cylinder by A/D converting output of a sensor at high speed and comparing values before and after the sampling of the output of the sensor. CONSTITUTION:The output of the pressure sensor 20 in the cylinder is properly amplified and inputted to a low-pass filter 22. At this time, cut frequency of the filter 22 is set higher than the expected knocking frequency. Accordingly, the output of the sensor including a high-frequency component is A/D converted 24 at the high speed and digital data are inputted to a control unit 26. Next, the output of the pressure sensor in the cylinder is sampled digitally and the rate of change of the digital data is calculated and in case the rate of change exceeds a prescribed value, it is decided to be knocking and in case the knocking is not detected, a maximum value of the data is regarded as the peak value of the pressure in the cylinder and detected by control of the control unit 26. In this way, the detecting accuracy of the pressure in the cylinder and the following property at the time of high rotation of the engine can be improved.
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