JPS59139841A - Magnetized yoke - Google Patents

Abstract

PURPOSE:To facilitate the magnetization of a pole for detecting frequency by forming a groove which perpendicularly crosses the hole at the center of the end face of a cylinder made of a magnetic material, winding a main pole forming coil, and forming slots of a fine pitch on the outer periphery of the end face and winding a coil. CONSTITUTION:A hole 24 is formed at the center of the end face 16' of a cylinder made of a magnetic material, and a groove 17' which perpendicularly crosses the hole 24 is formed. An exciting coil 18 having thick diameter as shown is wound in the groove 17'. A groove 25 is formed on the circumference of the end face 16' to form an outer periphery 16'', grooves 19 are formed at a fine pitch on the outer periphery 16'' in a pectinated teeth, and exciting coil 26 of fine diameter is wound in the groove 19. A thin magnetic material plate 4 for a field magnet is contacted with the end face 16' of the cylinder, coils 18, 19 are energized to form a main pole 12 and frequency detecting poles 13(N, N' and S, S'). In this manner, a field magnet 4 is inexpensively manufactured in mass production, thereby reducing the motor in size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention makes it possible to easily form a frequency detection magnetic pole superimposed on the magnetic pole of the king magnet of a motor, and also makes it possible to easily form a sine wave N magnet on the king magnet. The present invention relates to a magnetized yoke.

In a disk type brushless motor used in a direct drive type cassette tape recorder, etc., it is necessary to obtain a detailed rotational speed signal.

Referring to such a disc-type brushless motor 1, a disc-shaped rotor yoke 3 is fixed to the motor shaft 2, and a ring-shaped field magnet is mounted on the lower surface of the rotor yoke 3 as shown in FIG. 4 is fixed with adhesive.

A center spindle 5 is formed at the tip end of the motor shaft 2, and its lower end 1111I is rotatably supported by a bearing 6. A stator yoke 7 is fixed to the bearing 6, and on this stator yoke 7, as shown in the third electrical diagram, three fan frame-shaped military armature coils 31 are glued and fixed at equal intervals so as to overlap in plane. ing. A magnetoelectric transducer 9 for detecting the rotational position is accommodated in the cavity within the frame of the armature coil 8. A disk-shaped printed circuit board 10 is fixed to the upper surface of the armature coil, and the surface of this printed circuit board 1o has a comb-shaped conductive node for detecting the rotational speed of the rotor. Yuichi-nin 11 has been formed. The printed circuit board 10 and the field magnet 4 face each other with a small space interposed therebetween.

FIG. 2 is a plan view of the field magnet 4 of FIG. 1. As shown in FIG. 2, the main magnetic pole 2 of the field magnet 4 is
The H magnet is formed into a four-pole one with N and S magnetic poles arranged south at equal intervals, and about 18 mm around the periphery for detecting the rotor rotation speed.
A zero-pole frequency detection magnetic pole 13 is formed. N,S
is more strongly magnetized than N/ and S/.

FIG. 5 is a perspective view of the magnetizing yoke 14 for explaining a conventional method of magnetizing the main magnetic pole 12. This magnetizing yoke 14 is connected to an end surface 1 of a cylindrical body 15 made of a ferromagnetic material such as pure iron.
6, insert Tp117 which is orthogonal at the center, and excitation coil 18 for forming the main magnetic pole 12 for driving.
It is fully enclosed. By bringing this into contact with a magnet and passing it through the excitation coil 18, the four main magnetic poles 12 are magnetized.

In this way, after first magnetizing the main magnetic pole 12, a dedicated magnetizing yoke (not shown) for magnetizing the frequency detection magnetic pole 13 is used to magnetize the frequency detection magnetic pole 13 relatively weakly.
iB. Alternatively, this process may be reversed.

Therefore, the magnetic flux density waveform in the gap formed by the field magnet 4 is as shown in FIG.

As shown in FIG. 6, the magnetic flux density waveform formed by the frequency detection magnetic pole 13 is superimposed on the magnetic flux density waveform formed by the main magnetic pole 12. A waveform with fine irregularities is formed at the peaks or valleys.

FIG. 4 is a plan view of the printed circuit board 10 of FIG. 1. On the surface of the printed circuit board 100, in a portion facing the field magnet 40 and the frequency detecting magnetic pole 13, a comb-shaped conductive conductor (e-turn) 1 is formed as shown in FIG.

The pitch of the conductive/e-turns 11 is the same as the pitch of the frequency detecting magnetic poles 13 shown in FIG. An electromotive force is generated in each line segment in the same direction according to the rotational speed of the frequency detection magnetic pole 13, and a detection output of a frequency corresponding to the rotational speed of the rotor is obtained from an output terminal (not shown) of the conductive pattern 11.

Although the pulsed magnetic flux generated by the frequency detection magnetic pole 13 is intermittently interrupted, since the conductive A-turn 11 is formed all around the circumference as shown in FIG. 4, the detection output can be obtained as a continuous wave. Even if there is pitch unevenness in the magnetic poles 13 for frequency detection, the pitch unevenness is averaged out by the conductive A-turn 11, and when the rotational speed of the rotor is constant, a detection output of a constant frequency can be obtained.

A variation in the rotor rotational speed is extracted as a frequency modulation component of the detection output.

The disk-type brushless motor 1 having the above-mentioned rotational speed detection mechanism has recently attracted much attention, and various companies are desperately trying to develop it.

However, in the past, it took a lot of effort to form the field magnet 4 having the main magnetic pole 12 and the frequency detection magnetic pole 13. That is, this is because the magnetization of the main magnetic pole 12 and the magnetization of the frequency detection magnetic pole 130 had to be performed separately. Therefore, a magnetizing yoke for forming the main magnetic pole 12 and a magnetizing yoke for forming the entire frequency detecting magnetic pole 13 are required, making the device very expensive.

Further, the king-fracturing pole 12 of the field magnet 4 obtained by the magnetizing yoke 14 shown in FIG. 5 has a magnetizing waveform of a trapezoidal wave as shown in FIG. As is clear from FIG. 7, the fall and rise of the upper waveform 22 above the reference line 21 of the air gap magnetic flux density waveform formed by the main pole 12 and the lower waveform below are sharp. Tebru. Therefore,
The switching of the energization of the armature coil 8 is sudden, resulting in a large torque ripple, resulting in the drawback that the motor l cannot rotate smoothly.

This is especially fatal for the disc-type brushless motor 1 used in audio equipment.

Furthermore, in applications other than audio equipment, for example, when used as a disk-type fan motor, it has the disadvantage that it produces a harsh rotational sound when rotated at high speed.

The present invention is a magnetized yoke made based on the above circumstances,
The main magnetic pole and the M magnetic yoke for forming all of the frequency detection magnetic poles are integrated and miniaturized, so that the magnetizing yoke can be configured at a low cost, and the main magnetic pole can be easily magnetized with a sine wave. The object of the present invention is to make it possible to obtain a motor that can smoothly rotate by using the sine wave magnetized field magnet. In order to completely wind the excitation coil to form the main magnetic pole for driving, the above-mentioned is attached to the mounting yoke, which has a groove perpendicular to the hole formed in the center of the end face of the cylindrical body made of magnetic material. A ring-shaped groove is provided on the outer periphery of the end face, and grooves are formed on the end face of the outer periphery of the ring-shaped groove at a fine pitch to form frequency detection magnetic poles with a fine pitch, and the core part is excited. This can be quickly produced by providing a magnetizing yoke characterized in that a coil is wound around the cylindrical body, and the 1st and 11th surfaces of the end face facing the hole of the cylindrical body are formed into a mountain shape.

Hereinafter, with reference to FIG.
Visit TIFll and seek clarity. Note that parts that are common to those in FIG. 5 are marked with dashes.

FIG. 8 is a perspective view of the magnetizing yoke 14' of the present invention, and the magnetizing yoke 14' is configured to form four main magnetic poles 12. The magnetizing yoke 14' is fully inserted into the end face 16' of the cylindrical body 15' made of ferromagnetic material, with #117' placed at right angles to the main division provided in the center, and the fifth
As shown in the figure (see FIG. 9), an excitation coil 18 with a large expanded diameter is fully wound, a ring-shaped groove 25 is provided on the outer periphery of the end surface 16', and an end surface 16' on the outer periphery of the core portion 5 is provided. In order to form frequency detecting magnetic poles 13 with fine pitches, a large number of magnetic poles 1119 are formed at fine evenly spaced pitches.
Excitation coil 2 for forming frequency detection magnetic pole 13 with wire diameter Ic, lflb as shown in the figure (al, (bl)
6' and wrap it in a spiral shape.

Further, a side surface 27 of the end face 16' of the cylindrical body 15' facing the above-mentioned general section is formed on the side of the chevron-shaped part.

Therefore, first, using this magnetizing yoke 11I"k, JljJ
When a current is applied to the I magnetic coil 18 to magnetize it, a four-pole main magnetic pole 12 having N and S magnetic poles is formed as shown in FIG. 2, as a matter of course. Thereafter, when a current is passed through the excitation coil 26, the frequency detection magnetic pole 13 is formed on the outer periphery of the main magnetic pole 12, and the field magnet 4 shown in FIG. 2 is obtained. In addition, since the excitation coil 21 has a small wire diameter, the M1 wave number detection magnetic pole ] 3 is magnetized relatively weakly compared to the main magnetic pole 12 . Therefore, the pulsed magnetic flux generated by the frequency detection magnetic pole 13 hardly affects the armature coil 8. Incidentally, either of the excitation coils 18 and 21 may be excited first.

Further, the end face 16 portion forming the main magnetic pole 12 is
Since the main pole 12 has a mountain-like shape suitable for sine wave magnetization, when current is applied to the excitation coil 18, the main pole 12 is magnetized in a sine wave pattern.

RO, the magnetic flux density waveform formed by the main magnetic pole 12 magnetized in a sine wave is as shown in FIG.

FIG. 11 and FIG. 12 show other examples, in which magnetizing yokes 14'', 14 having deformed chevron portions 25', 251 are shown.
It is a top view of #.

This N magnetic yoke 1/, 14'' forms a (9) o8
The air gap magnetic flux density waveform of the in-wave is as shown in FIGS. 13 and 14.

Since the present invention has the above configuration, the N magnetic yoke for forming the entire main magnetic pole and the magnetizing yoke for frequency detection are integrated, so that the main magnetic pole and the frequency detection magnetic pole can be easily magnetized. Therefore, the field magnet shown in FIG. 2 can be mass-produced at low cost. Furthermore, since the magnetizing yoke having such a function is integrated and made compact, there is an advantage that it can be manufactured at low cost. Moreover, when the main magnetic pole is magnetized, the M magnet becomes sine wave magnetized, so if a disk type motor is formed using the sine wave magnetized field magnet, it will rotate cleanly. This effect can be obtained.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of a disc-type brushless motor, Figure 2
The figure is a plan view of a field magnet having a main magnetic pole and a frequency detection magnetic pole, Figure 3 is a general diagram showing how to install one of the m armature coil groups, and Figure 4 is a conductor (10) turned on the inside. 5 is a perspective view of a magnetizing yoke showing the conventional magnetizing force method for forming the main magnetic pole, and FIG. 6 shows the air gap formed by the field magnet in FIG. 2. FIG. 7 is a waveform diagram of the magnetic flux density in the air gap formed by the crown-break pole of the field magnet shown in FIG. 2. FIG. 8 is a perspective view of the magnetizing yoke showing an embodiment of the present invention. Figure 9 (al) is a plan view of Figure 8, Figure 9 fl is a partially enlarged explanatory diagram of the groove forming the frequency detection magnetic pole and the excitation coil, and Figure 10 is the magnetizing yoke of Figure 9. Fig. 11 and Fig. 1 are magnetic flux density waveform diagrams of the field magnet formed by
2 is a plan view of another magnetizing yoke, and FIGS. 13 and 14 are magnetic flux density waveform diagrams obtained by the field magnet formed by the magnetizing yoke of FIGS. 11 and 12. DESCRIPTION OF SYMBOLS 1... Disc ha 1 (brushless motor, 2... Motor shaft, 3... Rotor yoke, 4... Field magnet, 5... Center spindle, 6... Bearing, 7...
... Stator yoke, 8... Armature coil, 9...
Magnetoelectric conversion element,] 0... Printed circuit board, 11... Conductive notarne, 12... King magnet, 13... Magnetic pole for frequency detection, 14, 14'... Magnetizing yoke, 15...・Cylindrical body, 16... End face, 17... Groove, 18...〃1
Magnetic coil, 19...Groove, 20...Air gap magnetic flux density waveform, 2I...Group 4 Hi, 22...Upper waveform, H...
F section waveform, eraser...hole, 5...groove, A...excitation coil, 27...1-rule surface section, measurement...chevron section. 206

Claims (1)

[Claims] In order to fully wrap the excitation coil to form the entire main magnetic pole for driving, the outer periphery of the end surface of the magnetizing yoke is provided with a groove perpendicular to the hole provided in the center of the end surface of the cylindrical body made of magnetic material. A ring-shaped groove is provided in the outer periphery of the ring-shaped groove, and grooves are formed at a fine pitch on the end face of the outer periphery of the ring-shaped groove to form frequency detection magnetic poles with a fine pitch, and an excitation coil is provided in the core part. A magnetized yoke, characterized in that the cylindrical body is wound around the cylindrical body, and a side surface of the end face facing the hole of the cylindrical body is formed into a mountain shape.