JPH0475449A - Method and device for magnetizing permanent magnet piece for pole of electric rotating machine - Google Patents

Abstract

PURPOSE:To realize uniform and strong magnetization of permanent magnet piece by disposing magnetizing heads oppositely to the inside and the outside of the yoke of a rotating machine when the permanent magnet piece for pole secured to the inner circumferential face of the yoke of a cylindrical rotating machine is magnetized by means of the magnetizing heads. CONSTITUTION:Six pieces of not yet magnetized permanent magnets 2 are secured to the inner circumferential face of the cylindrical yoke 1 of a rotating machine with same intervals. A magnetizing device comprises inside section and outside section where an inside magnetizing head 10 opposing to each permanent magnet piece 2 is disposed radially around a cylindrical core 11, at the inside section, and an inside magnetizing coil 12 is wound around each magnetizing head 10. At the outside magnetizing section, an outside magnetizing head 14 is disposed oppositely to each permanent magnet piece 2 on the inside of an outside magnetizing yoke 13 and an outside magnetizing coil 15 is wound thereabout. When the magnetizing coils 12, 15 are connected in series and fed with an exciting current, lines of magnetic force 9 passing through the permanent magnet piece 2 pass in depthwise direction entirely over the surface 8 facing with the permanent magnet piece 2 thus magnetizing the permanent magnet piece 2 uniformly and strongly.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for magnetizing unmagnetized permanent magnet pieces fixed to the inner peripheral surface of a cylindrical rotating machine yoke constituting a stator or rotor of a rotating machine. Concerning improvements in magnetic methods and devices.

[Prior Art] As shown in FIGS. 5(a) and 5(b), rotating machines such as small motors are equipped with permanent magnet pieces on the inner peripheral surface of a cylindrical rotating machine yoke instead of the magnetic poles of an electromagnet. Stators or rotors that are fixed at regular intervals are often used. (a) is a fixed field type machine in which a rotor 4 is inserted into a stator 3 having permanent magnet pieces 2 fixed to the inner peripheral surface of a cylindrical rotating machine yoke 1. (b
) is a rotating field type, in which a rotor 3' having the same shape as the stator 3 in (a) rotates, and a rotor 4' having the same shape as the rotor 4 is fixed.

The permanent magnet piece is an alnico-based, ferrite-based, etc. permanent magnet, but it is fixed to the inner peripheral surface of the yoke of a cylindrical rotating machine in an unmagnetized state. magnetized using.

[Problems to be Solved by the Invention] A rotating machine yoke 1 has, for example, six unmagnetized permanent magnet pieces 2 fixed to its inner peripheral surface. It has a structure in which the same number of magnetizing heads 6 as permanent magnet pieces 2 are provided radially around the periphery.

When this is inserted into the cylindrical rotating machine yoke 1, each magnetizing head 6 closely faces each permanent magnet piece 2.

Therefore, when a large pulsed current is passed through the magnetizing coil 7 of the magnetizing head 6, each permanent magnet piece 2 is magnetized. However, with such a magnetization method, it is not possible to uniformly and strongly magnetize the entire opposing surface 8 of each permanent magnet piece facing the magnetization head in the easy magnetization direction indicated by arrow X, that is, in the thickness direction. The reason for this is that, as shown in Figure 7, the lines of magnetic force 9 generated by passing a pulsed current through the magnetizing coil are directed in the thickness direction at the central portion of the facing surface 8 facing the magnetizing head of the permanent magnet. However, in the peripheral portion, the magnetic field is oriented in an oblique direction, and the effective magnetic field for magnetization is weakened, and the strength of magnetization is weakened.

[Means for solving l111] The present invention provides a method for solving the above problems and an apparatus for implementing this method. A permanent magnet for a magnetic pole of a rotating machine, characterized in that the magnetizing head is provided facing inside and outside of a rotating machine yoke, and magnetized by passing a pulse current through the magnetizing head. A method for magnetizing a single magnet and an apparatus for implementing this method.

With the magnetizing device of the present invention, the lines of magnetic force are oriented in the thickness direction over the entire opposing surface of each permanent magnet piece, and the permanent magnet pieces are uniformly and strongly magnetized. Of course, the winding direction or current direction of each magnetizing coil is determined so that the inner and outer magnetizing heads, which face each other with the permanent magnet pieces in between, generate lines of magnetic force in the same direction.

In addition, the end face of each magnetizing head with respect to the facing surface of the permanent magnet piece should be made wider than the facing face of the permanent magnet piece, and the width of the end face of each magnetizing head with respect to the facing surface of the permanent magnet piece should be made wider than the opposing face of the permanent magnet piece. It is desirable to have them close together. Furthermore, the outer magnetizing yoke of the outer magnetizing section to which the outer magnetizing head is attached needs to have a cross-sectional area that is not saturated by the magnetic flux during magnetization.

[Effect] Next, the apparatus of the present invention will be explained in detail with reference to the drawings.

As an example, FIG. 1 shows a case in which six unmagnetized permanent magnet pieces 2 are fixed to the inner peripheral surface of a cylindrical rotating machine yoke 1 at equal intervals. The magnetizing device consists of an inner part and an outer part, and the inner part has inner magnetizing heads 10 facing each permanent magnet piece 2 arranged radially around a cylindrical core 11. Wind the magnetizing coil 12. The outer magnetizing section has an outer magnetizing head 14 disposed inside the outer magnetizing yoke 13 facing each permanent magnet piece 2, and an outer magnetizing coil 15 attached to the outer magnetizing head 14.
Wrap around.

An example of a circuit of an excitation current source that supplies an excitation current to each magnetizing coil is shown in No. 21g.

Each magnetizing coil is connected in series to the output terminal 16 of the excitation current source. When the switch 17 is switched to the charging side, the capacitor 18 is charged by the high voltage DC power supply 19 via the resistor 20. Next, switch the selector switch to the discharge side. Therefore, when a voltage is applied to the gate 22 of the thyristor 21 to make the thyristor conductive, the charge stored in the capacitor 18 becomes an instantaneous pulse current 1 that flows through each magnetizing coil 12, 15 and each permanent magnet piece 2. magnetize. At this time, the lines of magnetic force 9 passing through the permanent magnet piece pass in the thickness direction over the entire opposing surface 8 of the permanent magnet piece 2, as shown in FIG. 3, and magnetize the permanent magnet piece 2 uniformly and strongly.

The magnetizing device of the present invention is effective for magnetizing pieces of permanent magnets such as alnico, ferrite, rare earth-Co, rare earth-iron-boron, etc., but especially rare earth magnets require a large magnetizing magnetic field. It is highly efficient for those that require it.

[Example 1] As an example, a rotating machine stator or rotor consisting of six poles was magnetized using the magnetizing device of the present invention shown in the first example.

In this case, the rotating machine yoke 1 has an outer diameter of 86 nm and an inner diameter of 80 I.
III+, a steel cylinder with a height of 30mm, and the permanent magnet piece 2 is a Nd-Fe-B magnet (compositional molar fraction is Nd
:Dy:Fe:B:A1=15:0.3 near 5.7:7
:2 at%), the raw metal elements are melted in a high frequency melting furnace,
After making the ingot into fine powder, by powder metallurgy method,
Magnet alloy powder was press-molded in a magnetic field of 10,000 0e under 1 ton Zd, sintered at 1,090°C for 2 hours, and then heat-treated at 550°C for 2 hours.
Magnetic properties are Br=120000-1Hc=180000
e, bHc=11500 0e, (BH)m=35M
GOe length 15mm, width 2511I11, thickness 311I
It is a plate-shaped body slightly curved in the lateral direction to match the radius of curvature of the cylindrical rotary machine yoke of I+.

The excitation current source was the one shown in FIG. 2, and the magnetization rate K was measured when a 1000 μF capacitor was charged and discharged at a voltage in the range of 1 to 4 kV, and the results are shown in FIG. In this case, the magnetization rate refers to the amount of magnetic flux φ1 that passes through the permanent magnet piece when the unmagnetized permanent magnet piece is fixed to the yoke and magnetized by the magnetizing device of the present invention, and the amount of magnetic flux φ1 that passes through the permanent magnet piece when the unmagnetized permanent magnet piece is fixed to the yoke. Before it sticks,
This is the ratio of 100 to the amount of magnetic flux φ2 that passes through the permanent magnet piece when it is fixed to the yoke after being completely magnetized with an electromagnet in advance. That is, = φ1/φ2xlOO% As is clear from the figure, according to the magnetizing device of the present invention, the magnetization rate is approximately 100% at a charging voltage of 2 kV or more.

[Comparative Example] FIG. 4 shows the results of measuring the magnetization rate K under the same conditions as in the example except that the conventional magnetization device shown in FIG. 6 was used.

As described above, in the conventional device, the magnetization rate barely reached 90% at a charging voltage of 2.7 kV or higher.

[Effects of the Invention] According to the magnetizing device of the present invention, unmagnetized permanent magnet pieces fixed to the yoke of a cylindrical rotating machine can be uniformly and strongly magnetized.
Not only can you obtain an excellent stator or rotor for rotating machines, but you can also keep the charging voltage for magnetizing to the required degree low, which reduces the heat generation of the magnetizing head and greatly extends its life. can be extended to This is particularly effective as a magnetizing device for permanent magnet pieces that require a large magnetizing magnetic field, such as rare earth magnets.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the state in which a rotary machine stator or a permanent magnet piece for a rotor is magnetized by the magnetizing device of the present invention, Fig. 2 is a circuit diagram of an excitation current source, and Fig. 3 is a magnetizing state of the magnetizing device of the present invention. Fig. 4 is a schematic diagram showing the flow of magnetic lines of force generated from the magnetic head; Fig. 4 is a graph showing the relationship between charging voltage and magnetization rate in the example and comparative example;
Figure (a) is a schematic diagram of a fixed field type rotating machine, (b) is a schematic diagram of a rotating field type rotating machine, and Figure 6 is a conventional magnetization device for attaching permanent magnet pieces for the stator or rotor of the rotating machine. FIG. 7 is a schematic diagram showing the flow of magnetic lines of force generated from a conventional magnetizing head. 16... Output terminal, 17... Changeover switch, 18... Capacitor, 19... High voltage DC source,
20...Resistor, 21...Thyristor, 22...
Gate, X... Direction of easy magnetization of permanent magnet piece, l... Pulse current. 1...Rotating machine yoke, 2...Permanent magnet piece, 3.4
'... Stator, 4.3'... Rotor.

Claims (1)

[Claims] 1) In a magnetizing method in which a permanent magnet piece for a magnetic pole fixed to the inner circumferential surface of a yoke of a cylindrical rotating machine is magnetized by a magnetizing head, the magnetizing head is opposed to the inside and outside of the yoke of the rotating machine. 1. A method for single-magnetizing a permanent magnet for a magnetic pole of a rotating machine, characterized in that a permanent magnet for magnetic poles of a rotating machine is magnetized by passing a pulse current through the permanent magnet. 2) In a magnetizing device that applies a pulse current to a magnetizing head to magnetize a permanent magnet piece for a magnetic pole fixed to the inner peripheral surface of a yoke of a cylindrical rotating machine, the magnetizing head connects the yoke of a rotating machine with the permanent magnet piece in between. A permanent magnet single magnetization device for magnetic poles of a rotating machine, characterized in that the inside and outside of the permanent magnet are opposite to each other.