Elektromagnet für einen Durchflussregelschieber

摘要

In an electromagnetic driving device, a fixing core (13) has a housing portion (14), in which a plunger (17) is housed to reciprocatingly move, and an attracting portion (16) toward which the plunger is attracted upon energizing a coil (20). The housing portion is provided with a ring portion (15), which is formed by machining an outer circumference wall thereof and whose thickness is thinner than that of a part of the housing portion adjacent to the ring portion to an extent that mechanical strength of the housing portion is not damaged practically. The ring portion is provided with a plurality of through-holes (15a) penetrating radially the wall thereof. Amagnetic flux area of the ring portion is limited due to the thin wall and the through-holes so that magnetic resistance is enlarged.