Patent ID: 8305176

Claim:
An electromagnetic actuator, which is incorporated into a device using a corrosive liquid, comprising: a magnetic pole piece in a shape of a pillar; an outer yoke in a shape of a tube that is corrosion resistant, and that is placed around a periphery of the magnetic pole piece; a bottom yoke that connects the magnetic pole piece and one end portion of the outer yoke; a bobbin coil that is attached to the magnetic pole piece, the bobbin coil including a first coil holding portion, and a second coil holding portion on a bottom yoke side; a stepped portion that is formed on an outer surface of the outer yoke to make a diameter on an opposite side to the bottom yoke smaller than a diameter on the bottom yoke side; a waterproof portion that prevents the corrosive liquid from entering at least where the bobbin coil and the magnetic pole piece are; a movable plate that is placed in the corrosive liquid to form a magnetic circuit together with the magnetic pole piece, the outer yoke, and the bottom yoke, wherein the movable plate is stored in a space into which the corrosive liquid flows from the device using the corrosive liquid, the space being separated from at least the bobbin coil and the magnetic pole piece by the waterproof portion and being created either inside the electromagnetic actuator, or between the device using the corrosive liquid and the electromagnetic actuator, and wherein the outer yoke is incorporated into the device using the corrosive liquid, on a reduced diameter side from the stepped portion.