Magnet holder and magnet unit

A magnet holder comprising:

• a cylindrical body defining opposing inner and outer peripheral surfaces and having opposing axial ends;
• a shaft attachment portion disposed within one axial end of the cylindrical body to which a shaft is press-fitted and fixed;
• and
• a magnet holding portion disposed within the other axial end of the cylindrical body opposite the shaft attachment portion and that holds a periphery of a magnet, the magnet holding portion comprising a space defined by an inner peripheral surface of the magnet holding portion and a radially-extending end surface of the shaft attachment portion on a magnet side thereof, the magnet holding portion being provided with a circumferentially-extending undercut portion that engages with the magnet in an axial direction on the inner peripheral surface of the magnet holding portion facing the magnet to prevent relative axial movement therebetween, wherein:
• the magnet holding portion and the shaft attachment portion are integrally formed of sintered metal;
• an outer peripheral surface and an end surface of the magnet holding portion and an inner peripheral surface of the shaft attachment portion are sized;
• the undercut portion is formed by plastic deformation of the magnet holding portion by a pressing force in an inner diameter direction generated by pressurizing an outer circumferential surface of the magnet holding portion during the sizing;
• the inner peripheral surface of the magnet holding portion has a circumferentially-extending tapered surface and a circumferentially-extending reverse tapered surface that continues from the circumferentially-extending tapered surface on a shaft attachment portion side;
• the circumferentially-extending tapered surface is inclined toward an inner diameter side of the magnet holding portion as the circumferentially-extending tapered surface approaches the shaft attachment portion;
• the circumferentially-extending reverse tapered surface is inclined toward an outer diameter side of the magnet holding portion as the circumferentially-extending reverse tapered surface approaches the shaft attachment portion;
• the undercut portion is formed by the circumferentially-extending reverse tapered surface;
• and
• a recess that engages with the magnet in a circumferential direction is provided on the radially-extending end surface on the magnet side of the shaft attachment portion to prevent relative rotation therebetween.