Patent ID: 8830019
Filing Date: 2014-09-09
Classification: H01F,H02K

Abstract:
1. A magnet structure comprising: a columnar bonded magnet having at least one pair of N and S poles that are alternately provided in an axial direction of the columnar bonded magnet, the columnar bonded magnet being a single piece; a tubular bonded magnet having a cylindrical tubular shape that is positioned concentrically with the axis of said columnar bonded magnet and surrounds the outer periphery of the columnar bonded magnet, the tubular bonded magnet having at least one pair of N and S poles that are alternately provided in the inner periphery of the tubular bonded magnet in the axial direction of the columnar bonded magnet, the tubular bonded magnet being a single piece; and a coil support portion having a cylindrical tubular shape with a coil embedded therein, the coil support portion being positioned concentrically with the axis of said columnar bonded magnet and surrounds the outer periphery of the columnar bonded magnet, the tubular bonded magnet surrounding the outer periphery of the coil support portion, wherein each pole of the columnar bonded magnet and each pole in the inner periphery of the tubular bonded magnet that are opposed to each other in the direction perpendicular to the axis of the columnar bonded magnet are of opposite magnetic polarity, and wherein the magnet structure is formed with yokeless permanent magnets.