Electromagnet magnetic circuit with permanent-magnet armature

A magnetic circuit for a direct current electromagnet such as a relay electromagnet, comprising a fixed core, two yokes each connected to a respective free end of the core, and at least one armature movable between two end positions, said armature comprising a permanent magnet having flux input and output faces disposed at right angles to the magnet axis and each provided with a pole piece, each yoke having a flat portion having at least one air gap surface, the flat portions of the yokes being located in substantially parallel planes, said pole pieces having projecting end portions provided with air gap surfaces located on either side of the magnet axis, the flat portion of a first one of said yokes having two air gap surfaces and penetrating, with a clearance corresponding to the armature stroke, between the two mutually facing air gap surfaces of two end portions of the pole pieces located on a first side of the magnet axis, wherein the gap surfaces of the end portions of the pole pieces and of the flat portions of the yokes extend at right angles to the magnet axis, the armature is movable for translation in a direction corresponding substantially to the magnet axis, and, on a second side of the magnet axis, a second one of said yokes and a third yoke, both supported by a common free end of the core, have flat portions provided with mutually facing air gap surfaces between which two air gap surfaces belonging to at least one of the two pole pieces penetrate with a clearance substantially equal to the above-mentioned clearance.