公开(公告)号：US20170278609A1

公开(公告)日：2017-09-28

申请号：US15439975

申请日：2017-02-23

Applicant: TDK Corporation

Inventor： Jun HAGIWARA ,  Fumitaka BABA ,  Makoto IWASAKI ,  Satoshi KOGA

IPC: H01F7/02 ,  H02K1/04

Abstract: A rare earth magnet capable of reducing an eddy current loss by virtue of a low-cost, simple configuration, when mounted in a motor, is to be provided, where the rare earth magnet comprising: a magnet body comprising a rare earth element and iron; and a resistive layer formed on at least one surface of the magnet body, the resistive layer comprising a rare earth element, iron, and oxygen and having an average volume resistivity of 103 Ωcm or more and a thickness of from 3 to 25 μm, as is shown in FIG. 2.

公开(公告)号：US20170103835A1

公开(公告)日：2017-04-13

申请号：US15285178

申请日：2016-10-04

Applicant: TDK CORPORATION

Inventor： Tetsuya HIDAKA ,  Takuma HAYAKAWA ,  Makoto IWASAKI ,  Ayato KAKOKI ,  Naoto TSUKAMOTO ,  Fumitaka BABA

IPC: H01F1/053 ,  C22C28/00

Abstract: An R-T-B based sintered magnet includes “R”, “T”, and “B”. “R” represents a rare earth element including at least Tb. “T” represents a metal element except rare earth elements including at least Fe, Cu, Mn, Al, and Co. “B” represents boron or boron and carbon. With respect to 100 mass % of a total mass of the R-T-B based sintered magnet, a content of “R” is 28.0 to 32.0 mass %, a content of Cu is 0.04 to 0.50 mass %, a content of Mn is 0.02 to 0.10 mass %, a content of Al is 0.15 to 0.30 mass %, a content of Co is 0.50 to 3.0 mass %, and a content of “B” is 0.85 to 1.0 mass %. Tb2/Tb1 is 0.40 to less than 1.0, where Tb1 and Tb2 (mass %) denote a content of Tb at a surface portion and at a core portion, respectively.

公开(公告)号：US20170346432A1

公开(公告)日：2017-11-30

申请号：US15608067

申请日：2017-05-30

Applicant: TDK CORPORATION

Inventor： Makoto IWASAKI ,  Fumitaka BABA ,  Chikara ISHIZAKA

IPC: H02P21/22 ,  H02P6/08 ,  H02K41/03 ,  H02P27/04 ,  H02K1/27

Abstract: A motor includes a magnet and a coil. α2=[{(Br2−Br1)/Br1}/(T2−T1)]×100≧−0.10 and α3=[{(Br3−Br1)/Br1}/(T3−T1)]×100≦−0.12 are satisfied. In the magnet, Br1 (mT) is a residual magnetic flux density at T1 (° C.), Br2 (mT) is a residual magnetic flux density at T2 (° C.), and Br3 (mT) is a residual magnetic flux density at T3 (° C.), and α2 (%/° C.) is a temperature coefficient at a target temperature of T2 (° C.) with respect to a reference temperature of T1 (° C.), and α3 (%/° C.) is a temperature coefficient at a target temperature of T3 (° C.) with respect to a reference temperature of T1 (° C.) in conditions of T1=23, T2=60, and T3=180.