JPS5819151A - Magnetizing method for rotor magnet - Google Patents

Abstract

PURPOSE:To set the generated torque of a rotor magnet at constant value irrespective of the rotating angle of the magnet by magnetizing the poles of the magnet with constant intensity of magnetization to vary the magnetizing area in sinusoidal wave manner with respect to the rotating angle. CONSTITUTION:Poles of a rotor magnet for applying crossing magnetic fluxes to stator coils disposed oppositely to each other are magnetized with constant intensity of magnetization to vary the magnetizing area in a sinusoidal wave manner to the rotating angle. In other words, the magnetizing area which is determined by a curve a and an outer peripheral circle b is magnetized. This magnetization forms a magnetizing yoke conforming to the magnetizing area, a material to be magnetized to become a rotor magnet is disposed oppositely to the yoke, and the magnetization can be simply performed with the constant intensity of magnetization such as with a saturated magnetization.

Description

[Detailed description of the invention] The present invention relates to a method of magnetizing a rotor magnet.

For example, motors used in audio equipment are required to rotate smoothly without uneven rotation, and the generated torque must be constant regardless of the rotation angle of the rotor magnet.

Therefore, in the past, each magnetic pole of the rotor magnet was magnetized so that its magnetized area was uniform with respect to the rotation angle, and the strength of the magnetization varied sinusoidally with respect to the rotation angle. The magnetic flux density interlinking the opposing stator coils changes sinusoidally with respect to the rotation angle, and the drive current of the stator coils is controlled so as to change sinusoidally in synchronization with this sinusoidal change in the interlinking magnetic flux. By doing this, the force F generated in the negative stator coil is Fl = K
sin”θ, and the force F generated in the other stator coil
2 is Ft = K c05”θ (where K is a constant and θ is the rotation angle), and the resultant force F is F=F, + F,
=, and the generated torque was kept constant regardless of the rotation angle of the rotor magnet.

However, it is technically difficult to control the magnetization strength so that it changes sinusoidally, and it has not been possible to obtain an ideal magnetization state in the past.

The magnetization method of the present invention uses technically easy techniques such as saturation magnetization to make each magnetic pole of the rotor magnet uniform in strength with respect to the rotation angle, and by varying the magnetized area with respect to the rotation angle. , which solves the conventional drawbacks, and will be described below with examples. .

When the magnetized area is changed with respect to the rotation angle, the length of the stator coil interlinked with the magnetic flux changes according to the rotation angle. Therefore, if the magnetization strength is uniform and the magnetized area changes with the rotation angle, in order to keep the generated torque constant regardless of the rotation angle as in the past, the magnetized area of each magnetic pole must be adjusted to the rotation angle. On the other hand, it is necessary to change the sine wave.

The figure shows a six-pole magnetized rotor magnet (rotor magnet) 1 which is disposed opposite to a flat stator coil (not shown) to form a so-called planar facing type brushless motor, and the shaded area in the figure shows the rotor magnet of the present invention. This is a magnetized area that is magnetized using a magnetic method.

Curve a in the figure, which determines the magnetized region facing the stator coil, is a locus of point It is calculated as follows.

The center of the rotor magnet 1 is 0, each radius of the outer circumferential circle and inner circumferential circle C that determines the magnetized area is R1 and R, the distance between point X and center O is xl, and the maximum area for 80 is △Sma.
If x, △Smax = −(Rq −Rz)
-----(1)ΔS −ΔSmax・1sin3θ1
・・・・・・・・・・・・ (2) △s −−(R
, -, z') ...... Each relational expression (3) is established, and from these equations (x), (2) and (3), "-
(RF4) 5in311=T(R1-Z') is obtained, and the locus of X based on this equation (4) becomes the curve a to be found.

The magnetization of the magnetized region determined by the curve a and the outer circle is as follows:
By forming a magnetization yoke according to this magnetization region, and facing the magnetized material that will become the rotor magnet, it is possible to extremely easily perform magnetization with a constant magnetization strength by, for example, saturation magnetization.

According to the present invention, each magnetic pole of the rotor magnet can be magnetized with a constant magnetization strength, so the problem of uneven magnetization caused by the conventional method is solved and an ideal magnetized state can be obtained.

[Brief explanation of the drawing]

Figure: A plan view of a rotor magnet used for explaining the present invention is shown. l ・Rotor magnet. Patent applicant Nakamichi Co., Ltd. Representative Jinbe Nakamichi

Claims (1)

[Claims] A rotor characterized in that each magnetic pole of a rotor magnet that provides flux linkage to stator coils disposed opposite to each other is magnetized with a constant magnetization strength so that its magnetized area varies sinusoidally with respect to the rotation angle. Magnetization method.