JPS5928043B2 - Permanent magnet minute spacing magnetization device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for
The present invention relates to a magnetizing device for a permanent magnet having two or more pairs of magnetic poles.

An example of a magnetized permanent magnet conventionally used in small motors is shown in FIG.

An upper surface 2 of a permanent magnet 1 (hereinafter simply referred to as a permanent magnet) in the form of a ring or a disk is alternately magnetized with N poles and S poles. The shortest distance between adjacent same poles is f. In a motor incorporating this type of permanent magnet, when performing position detection for servo control, the more magnetic poles the permanent magnet has, the better the control accuracy will be. For this reason,
Conventionally, attempts have been made to magnetize permanent magnets by further shortening the distance between adjacent like poles. FIG. 2 shows a perspective view of a conventionally used magnetizing device.

In FIG. 2, reference numeral 3 denotes a cylindrical yoke made of electromagnetic soft iron with high magnetic permeability, and a large number of grooves 5 of the same shape are provided on the surface 4 at equal angular intervals, and windings 6 are formed on these grooves. By placing the permanent magnet 1 on the yoke surface 4 with its magnetized surface 2 facing down and passing current through the winding 6 in the direction of the arrow Tc, the convex portions 5a between the grooves 5 are alternately N, S, N,S
..., and the magnetized surfaces 2 of the permanent magnets 1 are alternately magnetized as described above. However, in this type of magnetizing device, there are certain limits to narrowing the magnetic pole spacing and increasing the number of magnetized poles. If we try to keep the spacing between adjacent same poles of permanent magnets to less than 1, there are 2 magnets within this spacing.
Since two conductive wires are required, even if the width of the magnetic pole convex portion is 0.01 mm, the diameter of the conductive wire must be 0.5 mm or less. If a thin wire of less than 0.5 wind resistance is used, the wire will not be able to withstand the large current, and there is no suitable wire.

Furthermore, since thin wires are used in such locations, the resistance between the terminals is large, preventing large currents from flowing. Furthermore, the groove width is 0.5m
If it is less than m, there are problems such as difficulty in insulation technology and difficulty in winding.In order to keep the distance between adjacent same poles of permanent magnet 1 to less than 1 mm, a jig for magnetization must be made. Therefore, it is thought that a large amount of cost and man-hours are required, and there is no example of this type of permanent magnet being manufactured. The present invention solves these problems of the prior art and provides a magnetizing device for use in permanent magnets with extremely narrow magnetic pole spacing. Examples according to the present invention will be described below.

FIG. 3 is a partially cut away perspective view of the cylindrical magnetizing device 9 according to the present invention.

17a shows the cut surface.

When creating the magnetizing device of the present invention, first, the cross-sectional shape L
The upper part of the circular S-pole yoke 15 is cut in the outer diameter direction, and a large number of convex parts 15a and concave parts 15b are provided alternately at appropriate intervals on the circumference.

Similarly, a cut is made in the inner diameter direction of the N-pole yoke 16, which has an L-shaped cross section and a circular planar shape, so that the convex portion 16a and the concave portion 16
A large number of b are provided. However, this is designed and machined in advance so that the convex part of the north pole engages with the concave part of the south pole. Next, conductive wires are wrapped with insulating material in the circumferential direction on the outer peripheral surface and the inner peripheral surface of the lower part of the S-pole yoke 15, respectively.
Glue each book together. Conductive wires are similarly bonded to the lower part of the N-pole yoke 16, as well as to the outer and inner peripheral surfaces. Next, S pole yoke 1
The upper part of the N-pole yoke 16 is engaged with the upper part of the N-pole yoke 16 through a gap so that the convex part fits into the concave part of the mating yoke, and the lower part is fixed to the base yoke 17.

By passing current through the conductive wires 8a, 8b in the direction shown on the conductive wires, magnetic flux lines are generated in the direction shown by the arrow 11. An annular and disc-shaped permanent magnet 10b is placed on the upper surface of the magnetizing device 9 to perform magnetization. FIG. 4 shows a part of a plan view of the magnetizing device shown in FIG. 3.

When the shortest distance between the S-pole convex portion 15a and the N-pole convex portion 16a is T, and the shortest distance between the N-pole convex portion 16a (5S-pole concave portion 15b is m), by regulating as t1<T2,
The magnetic flux in the circumferential direction, which is effective for magnetizing permanent magnets, is strengthened.

In order to prevent bending or chipping of the convex or concave portions of the S-pole yoke 15 or the N-pole yoke 16, the gap 19 is removed as necessary.
Filler such as plastic is embedded and fixed in place. The magnetizing device according to the present invention has a structure in which the conductive wire is not installed on the top surface of the magnetizing device, so although the number of magnetic poles is increased, it is not necessary to provide a conductive wire groove between the N and S convex parts as in the conventional case. In addition, the distance between adjacent like poles can be made as narrow as possible without embedding conductive wires, and as a result, it is possible to produce a multi-pole magnetized permanent magnet in which the shortest distance between adjacent like poles is 1 mm or less. . Here, the term "multiple poles" refers to a combination of two or more pairs of N and S magnetic poles. Figure 5 shows the magnetizing device shown in Figure 3 with an outer diameter of 56 m71! , inner diameter 48m77! ferrite magnet 1
0b is magnetized, and after magnetization, the surface of the magnet 10b is scanned in the circumferential direction with a probe using a Hall element, the surface magnetic field is measured, and the magnetic pole waveform is shown.

In FIG. 5, the number of poles is 10 including the north and south poles within an angle range of 10 degrees, but the number of poles can be freely obtained as required. Similarly, magnetization with the same magnetic pole spacing was obtained using samarium-cobalt and intermetallic compound permanent magnets. The outer diameter of this permanent magnet is 56m7n and the circumference is approximately 175m77! , and the circumference of the circle within an angle of 10 degrees? , that is, an arc with a length of 4.8 mm is included.

Since there are five like poles within an angle of 10 degrees, the spacing between like poles on the outer diameter of the permanent magnet is 0.96 mm.

Such minute spacing was made possible for the first time by the technique of the present invention in magnetized permanent magnets. FIG. 6 shows a part of a circumferential sectional view of a magnetizing device according to another embodiment of the present invention.

The gap distance between the S-pole convex part and the N-pole convex part is shorter in the upper part (T4) than in the lower part (T3). (T4-T3). With such a configuration, the effective magnetic flux 20a that magnetizes the permanent magnet 10b can be increased, and the invalid magnetic flux 20b can be decreased. As explained above, the present invention makes it possible to magnetize permanent magnets with minute spacing by using a magnetizing device with extremely narrow magnetic pole spacing, and has great industrial effects.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetized magnet, FIG. 2 is a perspective view of a conventional magnetization device, FIG. 3 is a partially cutaway perspective view of a magnetization device according to the present invention, and FIG. FIG. 5 is a partial plan view of the magnetizing device according to the invention, FIG. 5 is a diagram showing the magnetic pole waveform of the permanent magnet according to the invention, and FIG. 6 is a longitudinal sectional view in the circumferential direction of the magnetizing device according to the invention. 9: Magnetizing device, 8a, 8b: Conductive wire, 15: S-pole yoke, 16: N-pole yoke, 17: Base yoke.

Claims (1)

[Claims] 1. In a multi-pole magnetizing device for an annular or disk-shaped permanent magnet for an electric motor, a plurality of S-pole protrusions are connected to each other through a gap between a plurality of N-pole protrusions. A magnetizing device for permanent magnets at minute intervals, characterized by a conductive wire interposed in a yoke. 2. In the device according to claim 1, the shortest distance l_1 between the S-pole protrusion and the N-pole protrusion and the S-pole protrusion (
Alternatively, the shortest distance l_2 between the N-pole protrusion) and a part other than the N-pole protrusion (or a part other than the S-pole protrusion) is l_2.
A magnetizing device for permanent magnets at minute intervals, characterized in that the regulation is _1<l_2. 3. The micro-interval magnetization device for permanent magnets as claimed in claim 1, wherein the gap distance between the S-pole protrusion and the N-pole protrusion is narrower in the upper part than in the lower part.