An electromagnetically-operated fuel injection valve has a magnetic circuit comprising a valve casing, a stator core on which an electromagnetic coil is wound, an armature core, and an air gap between the stator core and the armature core. At least one of the valve casing, the stator core and the armature...http://www.google.fr/patents/US4676478?utm_source=gb-gplus-shareBrevet US4676478 - Electromagnetically-operated fuel injection valve
