Patent ID: 6265957
Filing Date: 2001-07-24
Classification: H01F,H01H

Abstract:
An electromagnetic actuator comprising:a fixed magnetic circuit made of ferromagnetic material comprising:a shell anda fixed core situated at one end of the shell and connected thereto,a movable assembly designed to slide along a fixed geometric axis between a rest position and an active position and designed to produce a mechanical work when moving from its rest position to its active position, the movable assembly comprising:a mobile core whose axial air-gap with the fixed core is reduced when the movable assembly moves from its rest position to its active position,an actuating means associated to the mobile core,a first return spring biasing the movable assembly to its rest position,an excitation circuit comprising at least one fixed control coil designed to generate a magnetic control flux in the magnetic circuit, which flux opposes the action of the first spring, the excitation circuit being designed to switch from an inrush mode in which it delivers a high power sufficient to move the movable assembly from its rest position to its active position, to a holding mode in which it delivers a lower power sufficient to hold the movable assembly in the active position,wherein in the active position, the axial air-gap between the mobile core and the fixed core is zero and the actuator comprises in addition:a second spring with a greater stiffness than that of the first spring, designed to return the movable assembly flexibly to its rest position,a first stop,a second stop, mobile and designed to operate in conjunction at least with the second spring and with the first stop, in such a way that in a first part of the axial travel of the movable assembly from its rest position to its active position, the second stop is not in contact with the first stop and the action of the first spring is preponderant, and that in the remaining travel up to the active position, the second stop is immobilized with respect to the first stop and the action of the second spring is preponderant.