Patent Application
20150130319
1. Field of the Invention
The invention relates to a rotor having a magnet, more particularly to rotor and a magnet thereof having an inner polygonal structure.
2. Description of the Related Art
Referring to
Referring to
Therefore, the object of the present invention is to provide a rotor and a magnet for a rotor that can eliminate the aforesaid drawbacks of the prior art.
According to one aspect of the present invention, there is provided an annular magnet for a rotor, comprising a hollow magnet body.
The magnet body has an outer circumferential surface that defines a cylindrical shape and an inner circumferential surface that defines an inlet hole. The inlet hole is adapted for receiving a back iron, and has a cross-section substantially shaped in an equiangular polygon. The magnet body further has a plurality of magnetic sectors that surround a central axis of the inlet hole. The magnetic sectors correspond respectively to the sides of the equiangular polygon. Each of the magnetic sectors has a magnetic polarity opposite to that of an adjacent one of the magnetic sectors. A thickness of the magnet body at a junction between two adjacent ones of the magnetic sectors is smaller than a thickness of the magnet body at a center portion of each of the magnetic sectors.
According to another aspect of the present invention, there is provided a rotor comprising the above-described magnet and a back iron mounted fittingly in the inlet hole, and formed with a through hole that extends along the central axis of the inlet hole.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
Referring to
The magnet body 41 has an outer circumferential surface 411 and an inner circumferential surface 412. The outer circumferential surface 411 defines a cylindrical shape, whereas the inner circumferential surface 412 defines an inlet hole 413. The inlet hole 413 has a cross-section substantially shaped in an equiangular polygon that has an even number of sides not smaller than four.
The magnet body 41 further has a plurality of magnetic sectors 414 that surround a central axis of the inlet hole 413.
The magnetic sectors 414 correspond respectively to the sides of the equiangular polygon. Each of the magnetic sectors 414 has a magnetic polarity opposite to that of an adjacent one of the magnetic sectors 414. A thickness of the magnet body 41 at a junction between two adjacent magnetic sectors 414 is smaller than a thickness of the magnet body 41 at a center portion of each of the magnetic sectors 414.
In this embodiment, the equiangular polygon is a regular octagon, and each of the sides of the equiangular polygon is straight. Preferably, referring to
The back iron 3 is shaped to correspond to the inlet hole 413, i.e., also having a cross section that is substantially equiangular polygonal, is mounted fittingly in the inlet hole 413, and is formed with a through hole 31 that extends along the central axis of the inlet hole 413. In summary, due to the inner polygonal structure of the magnet 4, the back iron 3 can be easily fitted therein. Since both the inner structure of the magnet 4 and the back iron 3 have axially symmetric shapes, the rotor is allowed to maintain rotational precision and stability when driven to rotate by a rotation shaft (not shown), and relatively smooth sine waves can be created during magnetization when the rotor rotates, resulting in enhancement of operation efficiency and reduction of both vibration and noise levels for a motor incorporating the rotor.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
