Electromagnetic actuator and fuel injection device

An electromagnetic actuator installed in a fuel injection device, comprising:

• a stator core which is disposed within a casing of the fuel injection device and has a built-in coil for generating a magnetic flux when energized;
• an armature which has a facing surface disposed to face one end surface of the stator core in an axial direction of the casing and has a first through hole extending along the axial direction, the armature being capable of reciprocating along the axial direction depending on the presence or absence of electromagnetic force generated from the stator core;
• a valve body which is inserted into the first through hole and has a flange part formed at a protruding part protruding from the first through hole toward the stator core with a larger diameter than that of the first through hole, the valve body being capable of opening and closing an outlet port of a back pressure chamber formed in the casing;
• and
• a first spring member which biases the valve body along the axial direction in a direction that closes the outlet port,
• wherein the valve body is disposed slidably along the axial direction in a state where the valve body is inserted into the first through hole, and
• wherein the electromagnetic actuator is configured such that, when the armature moves toward the stator core along the axial direction, the facing surface of the armature comes into contact with the flange part, whereby the valve body is moved in a direction that opens the outlet port.