Method for manufacturing Halbach magnet array

Patent metadata

Field	Value
Publication number	US-11735345-B2
Application number	US-202217804466-A
Country	US
Kind code	B2
Filing date	May 27, 2022
Priority date	May 28, 2021
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

The method for manufacturing the Halbach magnet array includes the steps of: (a) magnetizing at least two first magnetic material pieces in a direction parallel to a first direction, and (b) magnetizing at least one second magnetic material piece in a direction parallel to a second direction perpendicular to the first direction, in this order. In the step (a), the first magnetic material pieces and the second magnetic material piece are alternately arranged in the second direction with the first magnetic material pieces being each adhered to the adjacent second magnetic material piece, and the magnetization is performed under a condition in which a residual magnetization ratio r1 of the first magnetic material pieces is higher than a residual magnetization ratio r2 of the second magnetic material piece.

First claim

What is claimed is:

1. A method for manufacturing a Halbach magnet array, the method comprising the steps, in this order, of:
(a) magnetizing at least two first magnetic material pieces in a direction parallel to a first direction,
wherein the at least two first magnetic material pieces are alternately arranged with at least one second magnetic material piece in a second direction perpendicular to the first direction,
wherein the at least two first magnetic material pieces are each adhered to the adjacent second magnetic material piece,
wherein the at least two first magnetic material pieces each have an easy axis of magnetization parallel to the first direction,
wherein the at least one second magnetic material piece each has an easy axis of magnetization parallel to the second direction,
wherein the magnetizing is performed under a condition in which the at least two first magnetic material pieces and the at least one second magnetic material piece satisfy a formula (1) below:
r 1> r 2  (1)

wherein r 1 is a residual magnetization ratio of the at least two first magnetic material pieces, and is represented by a formula (2) below:
r 1= Br 1/ Brs 1  (2)

wherein Br 1 represents a residual magnetization of the at least two first magnetic material pieces when an external magnetic field parallel to the easy axis of the at least two first magnetic material pieces is applied to the at least two first magnetic material pieces, and
Brs 1 represents a saturated residual magnetization of the at least two first magnetic material pieces, and
r 2 is a residual magnetization ratio of the at least one second magnetic material piece, and is represented by a formula (3) below:
r 2= Br 2/ Brs 2  (3)

wherein Br 2 represents a residual magnetization of the at least one second magnetic material piece when an external magnetic field parallel to the easy axis of the at least one second magnetic material piece is applied to the at least one second magnetic material piece, and
Brs 2 represents a saturated residual magnetization of the at least one second magnetic material piece, and

(b) magnetizing the at least one second magnetic material piece in a direction parallel to the second direction.

2. The method according to claim 1 ,
wherein the at least two first magnetic material pieces and the at least one second magnetic material piece satisfy the formula (1) under normal temperature condition,
wherein the step (a) includes magnetizing the at least two first magnetic material pieces by an external magnetic field with a magnetic-flux density Ba,
wherein the step (b) includes magnetizing the at least one second magnetic material piece by an external magnetic field with a magnetic-flux density Bb, and
wherein Ba<Bb.

3. The method according to claim 1 ,
wherein the at least two first magnetic material pieces and the at least one second magnetic material piece satisfy a formula (4) below:
B 2− B 1>0.2 T   (4)

wherein B 1 represents a magnetic-flux density of an external magnetic field with which the residual magnetization ratio r 1 of the at least two first magnetic material pieces becomes 98% at normal temperature, and
B 2 represents a magnetic-flux density of an external magnetic field with which the residual magnetization ratio r 2 of the at least one second magnetic material piece becomes 98% at normal temperature.

4. The method according to claim 1 ,
wherein the step (a) includes magnetizing the at least two first magnetic material pieces in a state where the at least two first magnetic material pieces have a temperature higher than a temperature of the at least one second magnetic material piece, and
wherein the step (b) includes magnetizing the at least one second magnetic material piece in a state where the at least two first magnetic material pieces have a temperature lower than a temperature of the at least one second magnetic material piece.

5. The method according to claim 4 ,
wherein the step (a) includes heating the at least two first magnetic material pieces, and
wherein the step (b) includes heating the at least one second magnetic material piece.

6. The method according to claim 4 ,
wherein the step (a) includes cooling the at least one second magnetic material piece, and
wherein the step (b) includes cooling the at least two first magnetic material pieces.

Assignees

• Toyota Motor Co Ltd

Inventors

• Kanada Keiu
• Sakaguchi Reimi
• Ito Masaaki
• Nomura Takuya
• Ichigozaki Daisuke
• Hiraoka Motoki
• Akita Mitsutoshi

Classifications

• H01F13/003 Primary

  Methods and devices for magnetising permanent magnets (permanent magnets H01F7/02) · CPC title

• H01F7/021

  Construction of PM (H01F7/0278 takes precedence; PM compositions H01F1/032) · CPC title

• H01F41/02 Primary

  for manufacturing cores, coils, or magnets (H01F41/14 takes precedence; for dynamo-electric machines H02K15/00) · CPC title

• H01F7/0205 Primary

  Magnetic circuits with PM in general · CPC title

• H01F7/0278

  for generating uniform fields, focusing, deflecting electrically charged particles (for magnetic separation by Lorentz force B03C1/023; specially adapted for NMR applications G01R33/383) · CPC title