Electromagnetic actuator, notably for hydraulic servo-control valve
First Claim
1. An electromagnetic actuator comprising a tubular magnetic shell, an annular field coil means disposed concentrically within the shell and adapted to be connected to a control direct electric current, an armature means formed of a permanent magnet disposed axially within the field coil and having an axial magnetization and two pole pieces attached to the side faces of the permanent magnet, one of said armature and field coil means being fixed and the other of said means being axially movable relative to said shell, and a repulsion member interposed between said shell and said movable means to exert on the latter a force opposed to the electromagnetic force exerted on said movable means by the control direct current supplied to said field coil means, said field coil means being axially longer than said armature means and pole pieces combined and including a pair of adjacent half-coils wound in opposite directions, each one of said half-coils overlapping respectively one of the two pole pieces.
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Abstract
Electromagnetic actuator, especially for actuating a hydraulic servo-control valve, which comprises a magnetic shell constituting a body of revolution and a concentric armature-forming permanent magnet, at least one annular field coil, the field coil and the armature being adapted to move axially in relation to each other. The movable member (field coil or armature) is caused to move by the resultant electromagnetic force resulting from the energization of the field coil to which a control direct current is applied and by the antagonistic force of a repulsion member incorporated in the magnetic shell. The field coil is longer than the armature so that the electromagnetic force is independent of the movement of the movable member and proportional to the control direct current. The movable member is caused to perform simultaneously a cyclic motion superposed to the axial movement in order to eliminate the friction hysteresis of the hydraulic valve.
60 Citations
12 Claims
- 1. An electromagnetic actuator comprising a tubular magnetic shell, an annular field coil means disposed concentrically within the shell and adapted to be connected to a control direct electric current, an armature means formed of a permanent magnet disposed axially within the field coil and having an axial magnetization and two pole pieces attached to the side faces of the permanent magnet, one of said armature and field coil means being fixed and the other of said means being axially movable relative to said shell, and a repulsion member interposed between said shell and said movable means to exert on the latter a force opposed to the electromagnetic force exerted on said movable means by the control direct current supplied to said field coil means, said field coil means being axially longer than said armature means and pole pieces combined and including a pair of adjacent half-coils wound in opposite directions, each one of said half-coils overlapping respectively one of the two pole pieces.
Specification