Piezoelectric engine knock sensor - detects oscillation of flexure element clamped to engine part transmitting pinking noise waves

摘要

The sensor uses a piezoelectric element (2) to detect oscillations indicating engine knock in a resilient flexure element (1). The latter is clamped at one end with the piezoelectric element (2) sandwiched between the clamp plates (3,4) which are rigidly attached to a part of the engine transmitting the noise caused by engine knock. The flexure element (1) is clamped so that it extends transverse to the oscillation direction of this engine part. The sensor may use two piezoelectric ceramic plates (2) each interposed between a respective clamp plate (3,4) and the flexure element (1) which is pref. of spring steel, the piezoelectric plates (2) having opposing polarisation directions. The sensor can be used in conjunction with a fuel mixture control and is designed to be robust and reliable.