Patent ID: 7075394

Claim:
An apparatus comprising: a plunger; a stator that forms a magnetic circuit in combination with the plunger, the stator further defining: an accommodating portion for supporting the plunger with the accommodating portion so that the plunger is capable of reciprocation; and an attracting portion, wherein a magnetic attractive force attracts the plunger in a reciprocating direction of the plunger and acts between the attracting portion and the plunger; and a coil that generates the magnetic attractive force when energized, wherein either one or both of at least an outer peripheral wall of the plunger and at least an inner peripheral wall of the accommodating portion form(s) a magnetic portion made of nickel phosphide, and the phosphorus content of the magnetic portion is set within a range of greater than 10% to less than or equal to 15% in mass percentage.