Minebea Company, Limited

Minebea Mitsumi Inc.

Fumitoshi Yamashita

Osamu Yamada

Noboru Menjo

Shiho Ohya

Shinsaku Nishimura

Akihiro Yamane

A motor includes poles P having a remanence Mr of 0.9 T or more, a coercivity HcJ of 0.80 MA/m or more, and a maximum energy product (BH)of 150 kJ/mor more, which sets a center point Pc of the magnetic poles in a circumferential direction on a rotor outer circumferential surface to a maximum thickness t, wherein when a line connecting the Pc and a rotational axis center Rc is Pc-Rc, a straight line connecting an arbitrary point Px in the circumferential direction on the rotor outer circumferential surface and the Rc is Px-Rc, an apex angle of the lines Pc-Rc and Px-Rc is &#x3b8;, a number of pole pairs is Pn, a circumferential direction magnetic pole end is Pe, and a magnetic pole end biasing distance &#x394;Lof the circumferential direction magnetic pole ends Pe is &#x3b1;&#xd7;t(&#x3b1; is a coefficient).

Inner rotor-type permanent magnet motor with annular magnetic poles

There is provided the manufacturing method of a laminated magnet film end product, including the steps of: a first step of preparing magnet films, each of the magnet films having a thickness of 40 &#x3bc;m to 300 &#x3bc;m, and having a nanocrystalline structure which is magnetically isotropic; a second step of applying a self-bonding resin composition with film formability on each of the magnet films so as to prepare a plurality of self-bonding magnet films, each being composed of a magnet film and a self-bonding layer; a third step of mechanically processing each of the plurality of the self-bonding magnet films so as to be solid or hollow disc; a fourth step of preparing a laminated magnet film by laminating the plurality of self-bonding magnetic films; a fifth step of melting each self-bonding layer of the laminated magnet film and then cooling and solidifying each self-bonding layer so as to integrally rigidify the laminated magnet film; and a sixth step of magnetizing the rigidified laminated magnet film.

Manufacturing method of laminated magnet film end product with self-bonding layer

Improvement of torque densities, miniaturization and weight saving for outer rotor type motors or permanent-magnet-field-type DC motors can be efficiently achieved by high-energy densification of a magnet. However, torque pulsation or armature reaction gives negative influences thereto. Further, in application of a slotless (coreless) structure eliminating the torque pulsation or the armature reaction, the magnetic resistance of motor magnetic circuits will be enhanced. For solving the above problems, there is provided an annular magnet that is opened in a reverse direction relative to the opening direction of a U-shaped segment fabricated in constantly-directed magnetic fields, the annular magnet having an anisotropic distribution where angles relative to inner peripheral tangent lines can be continuously changed in the range of approximately 0 to 90 degrees, and having energy density (BH)of 160 to 186 kJ/m.

Method of rare earth-iron based annular magnet and motor fabricated thereby

Anisotropic rare earth-iron based resin bonded magnet comprises: [1] a continuous phase including: (1) a spherical SmFeNbased magnetic material covered with epoxy oligomer where its average particle size is 1 to 10 &#x3bc;m, its average aspect ratio ARis 0.8 or more, and mechanical milling is not applied after Sm&#x2014;Fe alloy is nitrided; (2) a linear polymer with active hydrogen group reacting to the oligomer; and (3) additive; and [2] a discontinuous phase being an NdFeB based magnetic material coated with the epoxy oligomer where its average particle size is 50 to 150 &#x3bc;m, and its average aspect ratio ARis 0.65 or more, further satisfying: [3] the air-gap ratio of a granular compound on the phases is 5% or less; and [4] a composition where crosslinking agent with 10 &#x3bc;m or less is adhered on the granular compound is formed at 50 MPa or less.

Anisotropic rare earth-iron based resin bonded magnet

A micro rotor is disclosed and includes a plurality of circular or annular plate-shaped thick film magnets which each include an isotropic magnet with a thickness thaving an in-plane remanence Mr of 0.95 T or more and a coercivity HcJ of 400 kA/m or more and a non-magnetic material with a thickness tadapted to isolate two adjacent isotropic magnets where the ratio of t/tis eight or more and which are stacked on one another in multiple layers in the rotation axis direction, wherein at least two pole pairs are provided and a mean magnetic path of in-plane direction having a permeance (B/&#x3bc;oH) of five or more achieved by the magnet alone is provided, whereby eddy current is reduced. Also disclosed are a radial gap type brushless DC motor, a PM stepping motor and an electric generator which incorporate the above described micro rotor.

Micro rotor and rotary electric machine incorporating same

A method of manufacturing a rotor magnet for a micro rotary electric machine is provided which includes steps of: a process in which a plurality of thick films, each of which is made of nanocomposite texture composed of &#x3b1;Fe and R-TM-B where R is either 10 to 20 atomic % Nd or 10 to 20 atomic % Pr, B is 5 to 20 atomic % and TM is either Fe or partly Co-substituted Fe with 0 to 16 atomic %, are formed into a laminated magnet including isotropic nano-crystalline texture which contains &#x3b1;Fe and RTMB and which has a remanence, Mr, of 0.95 T or more; and a process where the laminated magnet is multi-polar magnetized in-plane of the thick films.

Growing community of inventors

Kitasaku-gun, Japan

Fumitoshi Yamashita