Abstract: A ferromagnetic actuator having, in a housing, a ferromagnetic circuit defining an axial travel interval for an armature (22) of ferromagnetic material for axially driving a rod between two extreme positions in which the armature bears against poles of the ferromagnetic circuit, resilient return means provided to hold the valve at rest in a middle position between the extreme positions, and at least one coil carried by the circuit and enabling the armature to be brought in alternation into both positions. The rod carries a radially-magnetized bar of length not less than the travel distance of the armature, and the housing carries at least one magnetic flux sensor placed in a zone having low exposure to the field created by the coil(s).

Abstract: The electromagnetic valve actuator has an armature (22) of ferromagnetic material fixed to the stem of the valve, springs are provided to hold the valve at rest in a middle position between a fully open position and a closed position, and a single coil (38) is mounted on a ferromagnetic circuit. In combination with the armature, the magnetic circuit presents two stable magnetic flux paths both of which correspond to an airgap of small size.

Abstract: An electromagnetic actuator rotatable about an axis including a stator magnet circuit (2) with an inner pole (9) having a central core (11), a first pole shoe (12) forming the continuation of the core at one axial end of the stator circuit and extending through an angle of approximately 180.degree., and a single coil (3) coaxially surrounding the central core (11), the core (11) and the coil (3) being off-center relatively to the axis of rotation; and an outer pole (10) having a lateral armature (13.sub.2) in the form of a tubular sector outside the coil (3) and parallel to the core (11), and a second pole shoe (14) forming the continuation of the armature (13.sub.2) at the axial end of the stator circuit and extending through an angle of approximately 180.degree.; the ends of the central core (11) and of the armature (13) which are remote from the respective pole shoes being mutually in contact.

Abstract: Variable-reluctance absolute-angular-position sensor including at least one tator member (A). The stator member includes at least one fixed armature (2) made of soft ferromagnetic material, with a central core defining two mutually opposed transverse faces (9, 10) shaped in order to define an air gap (11) of non-constant thickness between them. At least one annular coil (4) surrounds the cores; and at least one rotor member (B) which includes at least one disc (3) extends into the abovementioned air gap and rotates about an axis (X) substantially coaxial with the core. The disc is made of a soft ferromagnetic material or a non-magnetic material which is a good electrical conductor.

Abstract: A variable reluctance absolute angular position sensor, having at least one stator detector (2). The dector includes: at least one stationary magnetic circuit (4, 4', 4") of ferromagnetic material provided with a length of annular housing (5, 5', 5"), and extending over an angular sector .alpha.; and at least one annular winding (6) housed in part in the annular housing; and at least one rotor unit (3) comprising at least one annular segment (7) of ferromagnetic material extending over an angular sector .beta. of no more than 360.degree.-.alpha., and situated facing the winding (6) and being rotated coaxially with the winding (6) while facing the winding in such a manner that magnetic flux passes radially between the stator detector (2) and the rotor unit (3).