Detecting knock vibrations in IC engine - using flexural piezoelectric vibrator with two different frequency vibrating sections

摘要

The sensor for detection of vibrations associated with knock in i.c. engines has a piezoelectric flexural vibrator which can be simply mounted. The vibration Q and resonant frequency can be determined during assembly. The Q is mainly determined by the vibrator material. A simple contact arrangement is also possible. The vibrator has an attachment section (7) for mounting it on the combustion engine and one or more sections (3,5) free to vibrate. The attachment section has a larger cross-section in the direction than the vibrating sections. Two tongue-shaped vibration sections may be used. These may be of different lengths to enable selective frequency detection using only one mechanical clamp. The transducer signals can be connected in parallel by using common electrodes.