Rare-earth magnet and linear motor using same

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 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 c denotes a coefficient which varies to gradually increase along one direction from the first surface toward the second surface in the thickness direction, in such a manner that it becomes minimum at the first surface, and becomes maximum at the second surface.