Bonded magnet, bonded magnet component, and bonded magnet production method

A method for producing a bonded magnet having a first non-action surface, a first action surface that is connected to said first non-action surface through a connection portion, and a third non-action surface that is connected to said first action surface through a connection portion and is connected to said first non-action surface through a connection portion, the bonded magnet having a substantially sector exterior shape, which is defined by said first non-action surface, the third non-action surface and the first action surface in a cross-sectional view, and has a predetermined central angle θ0 which is formed by said first non-action surface and said third non-action surface, the method comprising:

• charging a bond magnet composition that contains a magnetic material and a resin into a molding die cavity;
• and
• forming the bonded magnet while applying an external magnetic field to said cavity, wherein
• said external magnetic field is formed by permanent magnets,
• a first non-action-surface magnetizing magnet, a third non-action-surface magnetizing magnet, and a first action-surface magnetizing magnet as the permanent magnets are arranged to face parts corresponding to said first non-action surface, said third non-action surface, and said first action surface, respectively,
• the magnetic pole of said first non-action-surface magnetizing magnet on said corresponding part is the same as the magnetic pole of said third non-action-surface magnetizing magnet on said corresponding part,
• the magnetic pole of said first action-surface magnetizing magnet on said corresponding part is opposite to the magnetic pole of said first non-action-surface magnetizing magnet and said third non-action-surface magnetizing magnet on said corresponding parts,
• the first action surface corresponds to an arc of the substantially sector exterior shape in the cross-sectional view,
• the substantially sector exterior shape is a part of a circle having a center,
• a first line from the center to an end of the first action-surface magnetizing magnet intersects with the first action surface at a first point on the first action surface in the cross-sectional view,
• a second line from the center to another end of the first action-surface magnetizing magnet intersects with the first action surface at a second point on the first action surface in the cross-sectional view, and
• a ratio A/B satisfies:
• 0.3184n≤A/B<−0.04n3+1.47n2−14.03n+43, when a total number n of poles of said bonded magnet is not greater than 12 and said central angle θ0 is equal to or greater than 30°, and
• 0.3184n≤A/B, when the total number n of poles of said bonded magnet is greater than 12 and said central angle θ0 is less than 30°,
• wherein B denotes a half of an arc length of a segment on the first action surface in the cross-sectional view starting at the first point and ending at the second point, and A equals to a length of the first non-action surface corresponding to the first non-action-surface magnetizing magnet in the cross-sectional view.