PURPOSE:To enable to effectively activate an armature reaction by reducing an air gap between an interpole member and an armature smaller than that between a permanent magnet member and the armature, thereby reducing a magnetic resistance of the interpole. CONSTITUTION:A stator 1 is composed by securing in parallel a permanent magnet member 3 and a high magnetic permeability interpole member 4 on the inner surface of a yoke 2. An opposed air gap between the member 3 and an armature 5 is increased to allow the large dimensional tolerance capable of inexpensively producing the member 3, and the opposed air gap between the member 4 and the armature 5 is formed to be smaller than the permanent magnet by considering the small dimensional tolerance obtained by inexpensively cutting.
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