a m v to an extreme extent if it is desired to also detect the impacting of the armature 9 on the valve stem 2 by the detection of the armature motion the ratio m a m v must be changed by enlarging the armature mass only to such an extent that at the given sensitivity of the sensor system the moment of impact can still just be detected from the armature motion that is the mass ratio must be deliberately so changed that a detectable first rebound of the armature mass m a occurs an embodiment having an u201c asymmetrical u201d spring assembly will be discussed below in more detail in conjunction with a schematic showing in fig6 the modified electromagnetic actuator for operating an engine valve 2 is composed similarly to fig1 essentially of a closing magnet 6 and an opening magnet 7 which are spaced from one another and between which an armature 9 is reciprocated against the force of a resetting opening spring 12 and a resetting closing spring 3 the valve assembly is shown in the drawing in its closed position in the illustrated u201c classical u201d arrangement the closing spring 3 acts directly on the valve via a spring seat disk 4 affixed to the valve stem the armature guide bar 10 of the electromagnetic actuator is separated from the valve stem and as a rule a valve clearance vs is present in the closed position the opening spring 12 is supported by a spring seat disk 11 1 on the spring seat pin 11 so that during the opening motion.