Rare-earth magnet and linear motor using same

Patent metadata

Field	Value
Publication number	US-11239014-B2
Application number	US-201615560812-A
Country	US
Kind code	B2
Filing date	Mar 24, 2016
Priority date	Mar 24, 2015
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

Provided are a rare-earth magnet capable of realizing a high magnetic flux amount without using any back yoke, and a linear motor comprising a movable element using the rare-earth permanent magnet. A rare-earth permanent magnet-forming sintered body for forming a permanent magnet is integrally sintered while being formed into a given three-dimensional shape with a lengthwise cross-section having a first surface extending in a length direction thereof, a second surface lying at a distance from the first surface in a thickness direction thereof and extending in the length direction, and an edge surface of each of lengthwise opposite ends thereof. This sintered body is formed such that easy magnetization axes of the magnet material particles included in a central region thereof are oriented in such a manner as to be directed along an arch-shaped path.

First claim

The invention claimed is:

1. A rare-earth permanent magnet-forming sintered body comprising magnet material particles containing a rare-earth substance, wherein the magnet material particles are integrally sintered while being formed into a single sintered body having a given three-dimensional shape with a lengthwise cross-section having a length defined by the opposite edge surfaces at the opposite ends of the lengthwise cross-section, said sintered body having a first surface extending in a length direction thereof, a second surface lying at a distance from the first surface in a thickness direction thereof and extending in the length direction, and an edge surface of each of lengthwise opposite ends thereof, wherein:
in a central region of the sintered body located between a first end region and a second end region on the respective sides of the opposite ends, when viewed in the length direction, easy magnetization axes of the magnet material particles included in the central region are oriented in such a manner as to be directed along a path which enters an inside of the sintered body from the second surface at a position located on the side of the first end region with respect to a lengthwise center line of the central region passing through a lengthwise center of the central region and extending in a direction perpendicular to the first surface, and, after intersecting the lengthwise center line in the length direction, extends toward the second surface at a position located on the side of the second end region with respect to the lengthwise center line of the central region;
in the first end region, easy magnetization axes of the magnet material particles included in the first end region are oriented in such a manner as to be directed along a path which enters the inside of the sintered body from the second surface and extends toward the first surface;
in the second end region, easy magnetization axes of the magnet material particles included in the second end region are oriented in such a manner as to be directed along a path which enters the inside of the sintered body from the first surface and extends toward the second surface;
the easy magnetization axes of the magnet material particles included in the first and second end regions are oriented in parallel alignment in such a manner as to be directed in a direction approximately orthogonal to the first surface; and
the easy magnetization axes of the magnet material particles included in the central region are oriented such that, when the lengthwise center line of the central region is set as an origin in the length direction:
a distance measured from the lengthwise center line in a direction toward the second end region is denoted by a positive value for a variable b,
a distance measured from the lengthwise center line in a direction toward the first end region is denoted by a negative value for the variable b,
a distance from the center line to a boundary between the central region and each of the first and second end regions is denoted by bmax, where bmax is the absolute value of the distance from the center line to the boundary between the central region and each of the first and second regions, and
an orientation angle θ defined as an angle between an orientation direction of each of the easy magnetization axes and the first surface satisfies the following relationship:
θ(°)=(b/bmax)×c×90 (where: c denotes a constant; and the orientation angle θ has a positive value and a negative value, respectively, in a counterclockwise direction and in a clockwise direction, wherein: θ=−90° when (b/bmax)×c<−1; and θ=90° when (b/bmax)×c>1),
wherein the orientation angle is approximately constant in the thickness direction at positions where the distance b from the lengthwise center line has a same value.

2. The rare-earth permanent magnet-forming sintered body as recited in claim 1 , wherein the easy magnetization axes of the magnet material particles included in the first end region are oriented in parallel alignment in such a manner as to be directed in a direction approximately orthogonal to the second surface.

3. The rare-earth permanent magnet-forming sintered body as recited in claim 1 , wherein the easy magnetization axes of the magnet material particles included in the second end region are oriented in parallel alignment in such a manner as to be directed in a direction approximately orthogonal to the second surface.

4. The rare-earth permanent magnet-forming sintered body as recited in claim 1 , wherein the easy magnetization axes of the magnet material particles included in the first end region are oriented, in an area adjacent to the central region, in such a manner as to be directed along a path which inclines in a direction causing it to come close to the central region as becoming closer to the first surface.

5. The rare-earth permanent magnet-forming sintered body as recited in claim 1 , wherein the easy magnetization axes of the magnet material particles included in the second end region are oriented, in an area adjacent to the central region, in such a manner as to be directed along a path which inclines in a direction causing it to come away from the central region, as becoming farther away from first surface.

6. The rare-earth permanent magnet-forming sintered body as recited in claim 1 , wherein the magnet material particles are particles of Nd—Fe—B based magnet material.

7. A rare-earth permanent magnet produced by magnetizing the rare-earth permanent magnet-forming sintered body as recited in claim 1 .

8. A linear motor comprising a movable element having the rare-earth permanent magnet as recited in claim 7 , and a plurality of stationary magnetic poles arranged at a distance with respect to the first surface of the rare-earth permanent magnet.

9. The linear motor as recited in claim 8 , wherein the rare-earth permanent magnet of the movable element is disposed such that the length direction thereof becomes parallel to a moving direction of the movable element.

10. A rare-earth permanent magnet-forming sintered body comprising magnet material particles containing a rare-earth substance, wherein the magnet material particles are integrally sintered while being formed into a single sintered body having a given three-dimensional shape with a lengthwise cross-section having a length defined by the opposite edge surfaces at the opposite ends of the lengthwise cross-section, said sintered body having a first surface extending in a length direction thereof, a second surface lying at a distance from the first surface in a thickness direction thereof and extending in the length direction, and an edge surface of each of lengthwise opposite ends thereof, wherein:
in a central region of the sintered body located between a first end region and a second end region on the respective sides of the opposite ends, when viewed in the length direction, easy magnetization axes of the magnet material particles included in the central region are oriented in such a manner as to be directed along a path which enters an inside of the sintered body from the second surface at a position located on the side of the first end region with respect to a lengthwise center line of the central region passing through a lengthwise center of the central region and extending in a direction perpendicular to the first surface, and, after intersecting the lengthwise center line in the length direction, extends toward the second surface at a position located on the side of the second end region with respect to the lengthwise center line of the central region;
in the first end region, easy magnetization axes of the magnet material particles included in the first end region are oriented in such a

Assignees

• Nitto Denko Corp

Inventors

• Fujihara Makoto
• Hoshino Toshinobu
• Saito Shoichiro
• Fujikawa Kenichi

Classifications

• H01F7/02 Primary

  Permanent magnets {[PM]} · CPC title

• H01F1/0577 Primary

  sintered · CPC title

• H01F41/0273

  Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003) · CPC title

• H02K41/03

  Synchronous motors; Motors moving step by step; Reluctance motors (H02K41/035 takes precedence) · CPC title

• H01F41/028

  Radial anisotropy (for rotor or stator bodies H02K15/02) · CPC title