Electromagnetic actuator

摘要

A stator is provided with a ring-shaped outer stator-projection and a ring-shaped inner stator-projection. A plunger is provided with a ring-shaped outer plunger-projection and a ring-shaped inner plunger-projection. A magnetic force is generated at three portions between the plunger and the stator. The inner stator-projection has a first tapered surface and the outer plunger-projection has a second tapered surface. The first tapered surface and the second tapered surface confront each other when the plunger moves toward the stator.

主权项

1. An electromagnetic actuator comprising:
a coil for generating a magnetic force when energized; a plunger axially slidably supported; and a stator magnetically attracting the plunger in its axial direction when the coil is energized to generate the magnetic force; wherein: the magnetic force is generated at multiple attracting portions between the plunger and the stator; the stator is provided with a double-ring-shaped stator-projection axially projecting from the stator; the double-ring-shaped stator-projection is comprised of an outer stator-projection and an inner stator-projection concentrically; the plunger is provided with a double-ring-shaped plunger-projection axially projecting from the plunger; the double-ring-shaped plunger-projection is comprised of an outer plunger-projection and an inner plunger-projection concentrically; the inner stator-projection has an axial length which is shorter than that of the outer stator-projection; the inner plunger-projection has an axial length which is shorter than that of the outer plunger-projection; the double-ring-shaped stator-projection and the double-ring-shaped plunger-projection are able to slide into each other in such a manner that a first attracting portion is formed between the outer stator-projection and the outer plunger-projection, a second attracting portion is formed between the inner stator-projection and the outer plunger-projection, and a third attracting portion is formed between the inner stator-projection and the inner plunger-projection; and the first attracting portion has an axial length which is longer than that of the second attracting portion; and at least one of the first and second attracting portion is configured as two tapered surfaces confronting each other and being declined in a same direction with respect to an axial direction of the plunger.