| 摘要 |
PURPOSE:To improve the detection precision of the max. crank angle independently of the temperature variation of a piezoelectric element by obtaining the shift of the phase between the generated electric charge of a piezoelectric element and the output voltage of a pressure sensor and correcting the output of a calculating means according to the shift value. CONSTITUTION:Each signal of the pressure sensors 22a-22d for detecting the pressure in a cylinder by a piezoelectric element and of a crank angle sensor 25 for detecting the crank angle is input into a calculating circuit 24. In said calculating circuit 24, the fundamental value of the max. crank angle for providing the max. pressure in the cylinder is calculated as thetapmaxi, and outputted into a correction circuit 42. Into said correction circuit 42, the cooling-water temperature Tw corresponding to the temperature of the piezoelectric elements of the pressure sensors 22a-22d and 180 deg. signal Ca are input, and the shift deltaof thetapmaxi is calculated in accordance with the operation state, and the shift deltais added into thetapmaxi, and the max. crank angle is determined. Therefore, the max. crank angle of each cylinder can be correctly obtained from the output of the correction circuit 42.
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