| 摘要 |
[Problem] To reduce the size, lower the cost and increase and flatten the thrust of an electromagnetic actuator in which a plunger moves reciprocally. [Solution] The electromagnetic actuator comprises a yoke 130, a coil 180 arranged around the yoke, an armature 120 slidably arranged inside the yoke and integrally formed with a plunger 110, and a return spring 150 for returning the armature to a rest position, wherein the yoke 130 has, in a predetermined position on the axial direction L, a thickness-reduced annular gap groove 133 over part of an outer peripheral face 131, the thickness-reduced portion having a trapezoidal cross section widening outwards. Such a constitution allows shortening the magnetic path, allows increasing and flattening the electromagnetic force (thrust) generated for the displacement of the armature, allows increasing the acceleration (responsiveness) of the armature, and allows, for instance, reducing the parts count, simplifying assembly operations, and achieving cost reductions, while requiring no high-precision control of assembly positions.
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