Abstract: A vibration pickup has a pressure sleeve mountable directly or indirectly on a component causing vibrations, a spring, a sensor element which is held radially outwardly on the pressure sleeve with an axial tensioning by the spring and is electrically contactable, a wedge element provided between an inner periphery of the spring and an outer wall of the pressure sleeve, the wedge element being introduced axially with its wedge-shaped tipped side and radially clamps the spring in an end position and also holds components with the sensor element under an axial tensioning.

Abstract: It comprises a) a cylindrical base (1) formed of an axial barrel (2) protruding from an annular shoulder (3), through both of which there passes an axial hole (4), b) a washer (6) made of a piezoelectric material slipped over the barrel, c) means (71, 72) for picking off the electrical voltage there is between two radial faces of said washer, e) an annular mass (9), also slipped over the barrel (2) and e) a retaining means collaborating with the annular shoulder (3) to trap said washer (6) and said mass (9) between them. The retaining means consists of a bulge (17) protruding radially from said barrel (2) and formed of the material of a predetermined portion thereof, deformed under an axial force for crushing said base (1).

Abstract: A method for detecting a preinjection picks up and evaluates a vibration signal which occurs when a nozzle needle strikes a needle seat of an injector of a direct-injection internal combustion engine operating with a preinjection and a main injection. A sensor for structure-borne noise is provided on the cylinder outer wall for detecting the vibration signal. Based on the evaluation of the vibration signal a conclusion is made on the presence or absence of the preinjection in a combustion cycle. A device for detecting a preinjection is also provided.