Knocking detecting sensor

摘要

A knocking detecting sensor (1) includes a piezoelectric element plate (8) for detecting vibration due to knocking generated in an internal combustion engine and a main metallic sleeve (5) for supporting the piezoelectric element plate (8) on the side of one face. The sensor (1) is attached to a prescribed attaching unit (30) of an internal combustion engine. The piezoelectric element plate (8) is formed in a flat axis-symmetrical shape at a position relative to an axial line (O) that is substantially orthogonal to the attaching face (30a) of the attaching unit (30). The main metallic shell (5) has an opposite face (35) to the attaching face (30a) of the attaching unit (30), and has a notch portion (37) opening toward the opposite face (35) at a position a prescribed distance away from the axial line (O). By providing the notch portion (37), the center of gravity (G) of the sensor (1) can be corrected so that it approaches the axial line (O).