Magnets with Varying Magnetization Direction and Method of Making Such Magnets

Abstract

A permanent magnet in which the magnetization direction varies with location to optimize or restrict a magnetic field property in a selected direction at a selected point. The magnetic field property may be, for example, the transverse magnetic field, axial magnetic field, axial gradient of the transverse magnetic field, transverse gradient of the transverse magnetic field, axis gradient of the axial magnetic field, transverse gradient of the axial magnetic field, the product of the transverse magnetic field and the transverse gradient of the transverse magnetic field, the product of the transverse magnetic field and the axial gradient of the transverse magnetic field, the product of the axial magnetic field and the transverse gradient of the axial magnetic field, or the product of the axial magnetic field and the axial gradient of the axial magnetic field. The magnet may be formed of one or more segments in which the magnetization direction varies smoothly and continuously, or the magnet may be formed of a plurality of segments in which the magnetization direction is constant. A method of making and using such magnets is also disclosed.

1 - 10 . (canceled)  
     
     
         11 . A method of making a permanent magnet in which the magnetization direction varies with location to optimize a desired magnetic field property at a selected point in a selected direction, the method comprising: determining a desired shape; providing a blank of permanent magnetic material in the desired shape; and magnetizing the magnet to have a magnetization direction that varies in three dimensions so that the magnetization direction at each location in the magnet is in a direction that substantially conforms to a magnetization direction α determined as a function of an angle θ from the location to the selected point, which optimizes the desired magnetic field property at the selected point in the selected direction.  
     
     
         12 . (canceled)  
     
     
         13 . A method of making a permanent magnet in which the magnetization direction varies with location to optimize a desired magnetic field property at a selected point in a selected direction, the method comprising: determining a desired shape; providing a blank of permanent magnetic material in the desired shape; and magnetizing the magnet to have a magnetization direction that varies in two dimensions so that the magnetization at each location in the magnet is in the direction that substantially optimizes the desired magnetic field property at the selected point in the selected direction.  
     
     
         14 . (canceled)  
     
     
         15 . A method of making a permanent magnet in which the magnetization direction varies with location to optimize a desired magnetic field property at a selected point in a selected direction, the method comprising: determining a desired shape; assembling a plurality of permanent magnet segments into a shape substantially conforming to the desired shape; the magnetization direction of each permanent magnet segment varying in three dimensions so that the magnetization direction of each permanent magnet segment substantially conforms to a magnetization direction α determined as a function of an angle θ from the selected point to the magnet segment, which optimizes the desired magnetic field property at the selected point in the selected direction.  
     
     
         16 . (canceled)  
     
     
         17 . A method of making a permanent magnet in which the magnetization direction varies with location to optimize a desired magnetic field property at a selected point spaced from the magnet face and in a selected direction, the method comprising: determining the desired shape; assembling a plurality of permanent magnet segments into a shape substantially conforming to the desired shape, the magnetization direction of each permanent magnet segment varying in two dimensions so that the magnetization direction of each permanent magnet segment substantially conforms to a magnetization direction α determined as a function of an angle θ from the selected point to the magnet segment, which optimizes the desired magnetic field property at the selected point in the selected direction.  
     
     
         18 . (canceled)  
     
     
         19 . (canceled)  
     
     
         20 . The method according to  claim 17  wherein the direction of magnetization throughout each permanent magnet segment is constant.  
     
     
         21 . The method according to  claim 20  wherein the direction of magnetization throughout each permanent magnet segment is the direction which, at the center of mass of the segment, provides the maximum contribution to the desired property.  
     
     
         22 . The method according to  claim 20  wherein the direction of magnetization throughout each permanent magnet segment is the direction which, at the effective magnet center, provides the maximum contribution to the desired property.  
     
     
         23 . The method according to  claim 20  wherein the size and position of the permanent magnet segments is selected so that the difference in the direction of magnetization direction between adjacent magnet segments is less than about 45°.  
     
     
         24 . The method according to  claim 23  wherein the size and position of the permanent magnet segments is selected so that the difference in the direction of magnetization direction between adjacent magnet segments is less than about 30°.  
     
     
         25 . The method according to  claim 20  wherein the magnetization direction throughout each permanent magnet segment is not constant.  
     
     
         26 . The method according to  claim 20  wherein the desired magnetic field property is selected from transverse magnetic field, axial magnetic field, axial gradient of the transverse magnetic field, transverse gradient of the transverse magnetic field, axis gradient of the axial magnetic field, transverse gradient of the axial magnetic field, the product of the transverse magnetic field and the transverse gradient of the transverse magnetic field, the product of the transverse magnetic field and the axial gradient of the transverse magnetic field, the product of the axial magnetic field and the transverse gradient of the axial magnetic field, or the product of the axial magnetic field and the axial gradient of the axial magnetic field.  
     
     
         27 . (canceled)  
     
     
         28 . A method of making a permanent magnet in which the magnetization direction varies to control a desired property of the magnetic field at a selected point spaced from the magnet face, the method comprising: 
 determining a desired magnetization direction α as a function of an angle θ from the selected point to control the desired property of the magnetic field; selecting a cross section for the magnet in a plane containing the selected direction; providing a magnetic material in substantially the selected cross section, in which the magnetization direction α substantially conforms to the magnetization direction α determined by the function at each angle θ, where the function is given by: tan α=3 sin 2θ/(3 cos 2θ+/−1).    
     
     
         29 . The method according to  claim 28  wherein the magnetic material is monolithic with a continuously variable magnetization direction.  
     
     
         30 . The method according to  claim 29  wherein the magnetic material comprises a plurality of discrete magnet segments, with the magnetization direction of each segment having a constant magnetization direction that substantially conforms to magnetization direction α as a function of θ through the magnet segment.