Invention Title:

RARE EARTH SINTERED MAGNET, METHOD FOR PRODUCING RARE EARTH SINTERED MAGNET, ROTOR, AND ROTARY MACHINE

Publication number:

US20260221322

Publication date:

2026-07-30

Section:

Electricity

Class:

H01F1/057

Inventors:

Takanori WATANABE 🇯🇵 Tokyo, Japan

Yasutaka NAKAMURA 🇯🇵 Tokyo, Japan

Takaya SHIMOKAWA 🇯🇵 Tokyo, Japan

Tatsuya KITANO 🇯🇵 Tokyo, Japan

Akito IWASAKI 🇯🇵 Tokyo, Japan

Assignee:

MITSUBISHI ELECTRIC CORPORATION 🇯🇵 TOKYO, Japan

Applicant:

Mitsubishi Electric Corporation 🇯🇵 Tokyo, Japan

Smart overview of the Invention

The patent application describes a rare earth sintered magnet characterized by its main phase, which follows the general formula (Nd, Pr, R)—Fe—B. This main phase consists of crystal grains based on the Nd2Fe14B crystal structure and includes a core portion and a shell portion. The main phase is categorized into two types: the first main phase, where the concentration of Nd is greater than Pr, and the second main phase, where the concentration of Nd is less than Pr. These phases are mixed together, and a heavy rare earth element is present on at least part of their surfaces.

Field and Background

The innovation pertains to R-T-B-based permanent magnets, widely used in industrial motors due to their excellent magnetic properties. These magnets typically include neodymium (Nd) and are often enhanced with heavy rare earth elements like dysprosium (Dy) to improve performance at high temperatures. However, the high cost and procurement risks associated with these elements necessitate alternative methods to maintain magnetic properties while reducing dependency on heavy rare earth elements.

Challenges Addressed

Existing technologies, as described in Patent Literatures 1 and 2, face challenges in balancing the need for reduced heavy rare earth elements with maintaining high magnetic properties. The presence of heavy rare earth elements in main phases improves coercive force but can degrade residual magnetic flux density, critical for industrial applications. Additionally, the diffusion of these elements increases costs and procurement challenges, while existing structural designs do not sufficiently enhance anisotropic magnetic fields.

Proposed Solution

The disclosed rare earth sintered magnet addresses these challenges by incorporating a main phase with mixed Nd and Pr concentrations, reducing the need for heavy rare earth elements. The innovative structure includes a core and shell portion, with heavy rare earth elements strategically placed on the first and second main phases' surfaces. This design aims to enhance magnetic properties while minimizing the use of costly heavy rare earth elements.

Benefits and Applications

By optimizing the distribution of Nd and Pr and reducing heavy rare earth element usage, the invention promises improved magnetic properties compared to existing technologies. This advancement is particularly valuable for applications in industrial motors and other components requiring high magnetic performance, offering a cost-effective and resource-efficient solution.