Patent ID: 7621724
Filing Date: 2009-11-24
Classification: F04B

Abstract:
1. A stator for an electromagnetic pump comprising: a cylinder whose both end faces are respectively closed by a pair of frames; a movable member having a magnetic body, in which flange sections are formed at both axial ends and outer circumferential faces of the flange sections act as magnetic flux working surfaces, said movable member being accommodated in said cylinder and capable of reciprocally moving in the axial direction thereof; pump chambers being respectively formed between inner faces of the frames and both side faces of said movable member extended in the moving direction thereof; and air-core electromagnetic coils which are wound in opposite directions being fitted around a periphery of said cylinder, wherein yokes made of a magnetic material are provided to end faces of the electromagnetic coils to face the flange sections of the movable body; an outer yoke encloses outer faces of the yokes; a spacer made of a nonmagnetic material or an air space is provided between adjacent yokes, and wherein the movable member is repeatedly moved toward one of the sides according to a magnitude relation between magnetic attraction forces which work to the movable member and are generated by magnetic circuits formed between the flange sections and the adjacent yokes and between the flange sections, the end yoke, and the adjacent yokes when an electric current is supplied to the electromagnetic coils with the changing of the current direction, and wherein a restoring force for returning the movable member toward a center of a stroke is generated by magnetic circuits formed between the movable member and the adjacent yokes when the movable member is located on one of the sides and the electric current to the electromagnetic coils is turned off.