| 摘要 |
PURPOSE:To improve detecting accuracy of the internal pressure of a cylinder by correcting the output of a pressure sensor properly according to a temperature variation of a piezoelectric element. CONSTITUTION:The flow rate Q of the intake air is detected by an airflow meter 29 and controlled by a throttle valve 30 in a suction pipe 23. Further, a wall temperature Tw of a combustion chamber 31 is detected by a wall temperature sensor 32 and the number N of revolutions of an engine 21 is detected by a crank-angle sensor 33 incorporated in a distributor 26. On the other hand, a pressure sensor 34 which is shaped by molding as a washer of an ignition plug 25 constituted by the piezoelectric element detects the internal pressure of the cylinder acting upon the piezoelectric element via the plug 25 and outputs an electric charge signal Pa having an electric charge value corresponding to the detected internal pressure. Further, the meter 29 and the crank-angle sensor 33 constitute an operational state detecting means 35. Then, the signals from the means 35, the wall temperature sensor 32 and the pressure sensor 34 are inputted to a control unit 36 which calculates the internal pressure of the cylinder based on these pieces of information of sensor and controls a combustion state perfectly according to the result.
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