| 摘要 |
PURPOSE:To form a small sized sensor which is highly reliable and can be easily tuned to knocking frequencies by taking out the knocking frequencies by means of a resonance circuit by using a ceramic piezoelectric element for an oscillation detecting part. CONSTITUTION:Mounting holes 9 are provided at two places of the cylinder block surface of an engine 1 and both terminals of a ceramic piezoelectric element 3 are fixed therein via insulators 2. the oscillation intensity and frequency of the engine are converted to the magnitude and frequency of the voltage of the element 3. The voltage generated in the element 3 is amplified by an amplifier 4, and is connected to a resonance circuit 5, from which the signal based on knocking is taken out and is further amplified with an amplifier 6. The signal (a) is rectified by a rectifying circuit 7, and is further smoothed to the current voltage signal (b) proportional to knocking intensity. This signal (b) is inputted to a comparator 8, and is copared to a comparing voltage source Es. When the knocking intensity exceeds a permissible value, the output C of a comparator goes on, thereby deciding the presence or absence of the knocking. |
