Hitachi Metals, Ltd.

Takashi Sasaki

Masahiro Mita

Motohisa Hasegawa

Masahiro Masuzawa

Noriyoshi Hirao

An R&mdash;T&mdash;B-based, permanent magnet with improved resistance to the deterioration of magnetic properties by working, electroplating, etc. and to their change with time, wherein R is one or more of rare earth elements including Y, and T is Fe, part of which may be substituted by Co, has (a) a corrosion-resistant film layer having an average thickness of 5 &mgr;m or more on a surface of a sintered magnet having a composition consisting essentially of 20-45 weight % of R, 15 weight % or less of Co, 0.5-6 weight % of B, and 10 weight % or less of M selected from the group consisting of Al, Si, Nb, Mo, V, Mn, Sn, Ni, Zn, Ti, Cr, Ta, W, Ge, Zr, Hf and Ga, the balance being substantially Fe and inevitable impurities, and (b) a layer richer in rare earth elements than a main phase of R,Fe,B beneath the corrosion-resistant film layer.

R-T-B-based, permanent magnet, method for producing same, and permanent magnet-type motor and actuator comprising same

An R-T-B-based, permanent magnet with improved resistance to the deterioration of magnetic properties by working, electroplating, etc. and to their change with time, wherein R is one or more of rare earth elements including Y, and T is Fe, part of which may be substituted by Co, has (a) a corrosion-resistant film layer having an average thickness of 5 .mu.m or more on a surface of a sintered magnet having a composition consisting essentially of 20-45 weight % of R, 15 weight % or less of Co, 0.5-6 weight % of B, and 10 weight % or less of M selected from the group consisting of Al, Si, Nb, Mo, V, Mn, Sn, Ni, Zn, Ti, Cr, Ta, W, Ge, Zr, Hf and Ga, the balance being substantially Fe and inevitable impurities, and (b) a layer richer in rare earth elements than a main phase of R.sub.2 Fe.sub.14 B beneath the corrosion-resistant film layer.

R-T-B-based, permanent magnet, method for producing same, and permanent

Disclosed is a permanent magnetic field type rotating machine. The rotor core is made of a single chemical composition material comprising ferromagnetic and nonmagnetic zones. The nonmagnetic zones consists of a remolten and solidified metal structure and of a merely heated and cooled metal structure, and are present at portions of the rotor core where leakage flux is produced.

Permanent magnet field type rotating machine

A brushless motor having permanent magnets that can be used as a prime mover for automobiles, in place of internal combustion engines, since the motor can yield high torque during low-speed rotation, as in the case of conventional types of brushless motors and can be used at high torque and with excellent motor efficiency at rotations three times as high as that of conventional types. The brushless motor having permanent magnets according to the invention comprises

Brushless motor having permanent magnets

Disclosed is a permanent magnet field-type rotating machine of a high efficiency having an internal magnet-type rotor. The rotating machine comprises an internal magnet-type rotor having a plurality of permanent magnets embedded in a rotor yoke, and a stator disposed in opposed, spaced relationship to the rotor, with an air gap formed between the rotor and the stator. The rotor yoke comprises a member in which ferromagnetic regions and non-magnetic regions coexist, and the non-magnetic regions are disposed respectively at those positions of the rotor yoke where leakage magnetic flux is liable to be generated.

Growing community of inventors

Fukaya, Japan

Takashi Sasaki