Contoured-field magnets
AssigneeArnold Magnetic Technologies
InventorsGerhard Martinek, Urs Wyss
Life of this patent
Estimating the term…
Abstract
Apparatus and methods for manufacturing magnets, and magnets, having magnetically oriented grains, and apparatus including such magnets. The field of a permanent magnet may be shaped by applying an external field to the material from which the magnet is made in such a way as to magnetize different regions of the material in different directions. The apparatus may include, and the methods may involve, a metal-powder press that may press metal powder in the presence of a magnetic field. The press may compress the powder in an axial direction. The field may have flux lines that are transverse to the axial direction. The field may have flux lines that are along the axial direction.
Claims52
A method for producing a magnet, the method comprising:
- placing grains of magnetic powder in a press that defines a compression axis and a die;
- magnetically orienting the grains so that:
- in a first region of the die, radially apart from the compression axis, first grains have first magnetic dipole moments that are inclined, relative to the central axis, at a first angle that is oblique to the compression axis;
- in a second region of the die, substantially along the compression axis, second grains have second magnetic dipole moments that are substantially normal to the compression axis;
- and,
- in a third region of the die, opposite the first region, third grains have third magnetic dipole moments that are inclined, relative to the central axis, at a second angle that substantially mirrors the first angle;
- and
- pressing the grains, along the compression axis, into a compact during the orienting.
A method for producing a magnet, the method comprising:
- placing grains of magnetic powder in a press that defines a compression axis and a die;
- magnetically orienting the grains so that:
- in a first region of the die, radially apart from the compression axis, first grains have first magnetic dipole moments that are inclined, relative to the central axis, at a first angle that is oblique to the compression axis;
- in a second region of the die, substantially along the compression axis, second grains have second magnetic dipole moments that are substantially parallel to the compression axis;
- and,
- in a third region of the die, opposite the first region, third grains have third magnetic dipole moments that are inclined, relative to the central axis, at a second angle that substantially mirrors the first angle;
- and
- pressing the grains, along the compression axis, into a compact during the orienting.
A magnetic powder press comprising:
- a die for receiving magnetic powder, the die having a first direction and a second direction that is substantially orthogonal to the first direction;
- a magnetic flux source that is configured to provide magnetic flux substantially parallel to the first direction from a first region of the die to a second region of the die, the first and second regions being spaced apart from each other on opposite sides of a central region of the die;
- a first compression body having a first magnetic permeability;
- and
- a second compression body having a second magnetic permeability;
- wherein:
- the first and second compression bodies are configured to compress the powder along the second direction;
- and
- the first and second magnetic permeabilities are imbalanced so that, when the bodies compress the powder, the flux is deflected in the second direction:
- in the central region, by a first offset;
- and
- in the first and second regions, by a second offset that is less than the first offset.
A magnetic powder press comprising:
- a die for receiving magnetic powder, the die having a first direction and a second direction that is substantially orthogonal to the first direction;
- a magnetic flux source that is configured to provide magnetic flux substantially parallel to the second direction from a first region of the die to a second region of the die, the first and second regions being spaced apart from each other on opposite sides of a central region of the die;
- a first compression body having a first magnetic permeability;
- and
- a second compression body having a second magnetic permeability;
- wherein:
- the first and second compression bodies are configured to compress the powder along the second direction;
- and
- the first and second magnetic permeabilities are imbalanced so that, when the bodies compress the powder, the flux is deflected in the first direction:
- in the first region, by a first offset;
- and
- in the second region, by a second offset that is greater than the first offset.
A sintered hard magnet comprising:
- a plurality of first sintered grains having first magnetic easy directions substantially aligned together along a plane;
- a plurality of second sintered grains, on one side of the first sintered grains, the second sintered grains having second magnetic easy directions aligned together and inclined obliquely relative to the plane;
- and
- a plurality of third sintered grains, on an opposite side of the first sintered grains, the third sintered grains having third magnetic easy directions that substantially mirror the second easy directions.
A magnet having a substantially planar face, the magnet comprising:
- a plurality of first sintered grains having first magnetic easy directions aligned substantially parallel to the face;
- a plurality of second sintered grains, on one side of the first sintered grains, the second sintered grains having second magnetic easy directions aligned together and inclined obliquely relative to the face;
- and
- a plurality of third sintered grains, on an opposite side of the first sintered grains, the third sintered grains having third magnetic easy directions that substantially mirror the second easy directions.
A sintered powder hard magnet having a face, a diameter between about 5 mm and about 7 mm and a thickness between about 1.5 mm and about 3.5 mm, and defining, normal to the face, a central axis, the magnet generating a magnetic field that, at a location about 3 mm from the face and about 1 mm radially away from the central axis, has a component that is parallel to the central axis and has a magnitude that is greater than 400 Gauss.
A sintered powder hard magnet having a face, a diameter between about 5 mm and about 7 mm and a thickness between about 1.5 mm and 3.5 mm, and defining, normal to the face, a central axis, the magnet generating a magnetic field that, at a location about 3 mm from the face and about 1 mm radially away from the central axis, has a component that is parallel to the face and has a magnitude that is greater than 520 Gauss.
A sintered hard magnet having a magnetic axis that traverses from a first region of the magnet to a second region of the magnet, the magnet comprising:
- a plurality of first sintered grains in the first region having first magnetic easy directions aligned together substantially parallel to the axis;
- a plurality of second sintered grains in the second region and set apart from the axis, the second sintered grains having second magnetic easy directions that are inclined away from the axis.
A sintered powder hard magnet having a magnetic axis, the magnet comprising a top surface normal to the axis and a bottom surface normal to the axis, the bottom surface set apart from the top surface by a thickness that is between about 3 mm and about 6 mm, and generating a magnetic field that at a location about 4 mm from the top surface, has a component that is parallel to the axis and has a magnitude greater than 1500 Gauss.
An angular displacement indicator comprising:
- a sintered powder magnet having a planar face normal to a rotation axis;
- and
- a sensor configured to output a voltage that is proportional to an angular displacement between the magnet and the sensor, the magnet comprising grains that have magnetic dipoles that form a curved pattern that, near the axis, is substantially tangent the face, the sensor sensing a magnetic field from the magnet, the magnetic field parallel to the rotation axis.
Dependencies are inferred from the claim text.