JPH0822914A - Encoder magnet and its fixing structure - Google Patents

Abstract

PURPOSE:To avoid scattering of an encoder magnet in a motor even if the adhesion of the encoder magnet is peeled off by a method wherein the encoder magnet is assembled into discs for preventing a field magnet from slipping out of a slot, and the encoder magnet is wrapped up in a rotor and discs. CONSTITUTION:In the discs 11, 14, a loose hole with a shift is bored in the central part in the outer diameter the same as the maximum diameter of a rotor, while an encoder magnet 12 used for detecting the rotor position is assembled into one of the disc 11. Since the encoder magnet 12 is made opposite to the rotor 16 side in the disc 11, the whole surface of the encoder magnet 12 is covered with either the disc 11 or the rotor 16. In such a constitution, even if the encoder magnet 12 bonded onto the disc 11 is peeled off, the encoder magnet 12 can be held between the disc 11 and the rotor 16 so as not to scatter in the motor, thereby preventing a motor breakdown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder magnet for a brushless motor.

[0002]

2. Description of the Related Art FIG. 7 is a vertical sectional view of a shaft and a rotor, showing a fixing structure of the encoder magnet.

The rotor 76 has an even number of salient poles on its outer circumference and is laminated with silicon steel plates having slots for inserting field magnets at the bases of the salient poles, and field magnets 79 are inserted in the slots. Is configured. Since the field magnet 79 is not fixed in the axial direction, the field magnet 79 may fall out of the rotor slot. To prevent this, discs 74 are attached to both sides of the rotor. The encoder magnet 72 used for detecting the rotor position is fixed to the cover 71 and is fixed to the shaft 77 at a position apart from the rotor 76.

FIG. 6 is a diagram of a conventional encoder magnet and cover. Here, the case where the encoder magnet has four poles is taken as an example.

The encoder magnet 62 is a fan type magnetized in the thickness direction and opened at about 90 degrees, and four magnets are used. Further, in order to align the magnetic pole of the encoder magnet 62 with the magnetic pole position of the rotor, the cover 61 is provided with two scribe lines 61a at intervals of 90 degrees. The encoder magnet 62 has a fan-shaped circumferential end surface on which the scribing line 61 is formed.
It is fixed to the cover 61 by adhesion or the like so that the adjacent magnetic poles are reversed in accordance with a.

[0006]

However, there is a slot having an even number of salient poles on the outer periphery and a field magnet inserted into the base of each salient pole, and a rotor having a field magnet inserted into the slot. In a brushless motor that uses an encoder magnet to detect the position of the rotor, it is said that there are a large number of parts on both sides of the rotor, the disk that prevents the field magnets from slipping out of the slots, and the cover that fixes the encoder magnet. Had challenges. Further, there is a problem that when the adhesion of the encoder magnet is peeled off, the encoder magnet scatters in the motor and destroys the motor.

Further, the encoder magnet is manufactured by laminating a plurality of fan-shaped magnets with a large number of parts, and the work of adhering the magnets in accordance with the marking lines of the cover is very troublesome, but the encoder magnet There was a problem that the position accuracy of the magnet was not good.

[0008]

In order to solve the above problems, according to the present invention, an encoder magnet is incorporated in one of the discs for preventing the field magnet from coming out of the slot, and the encoder magnet is used as a rotor. It is characterized by a fixed structure of an encoder magnet wrapped with a disc.

Further, the encoder magnet is constituted by one ring-shaped magnet, and the magnet is fixed to the cover by adhesion or the like, and then magnetized together with the position of the magnetic pole of the rotor.

[0010]

1 is an exploded perspective view of a component fixed to a shaft according to an embodiment of the present invention. First, for easy understanding, the rotor will be described first.

The rotor yoke will be described with reference to FIG. FIG. 3 is a plan view of the rotor yoke 18. Rotor yoke 1
8 is composed by laminating silicon steel plates, and has a shaft 1 at the center.
7 and a hole for loose fitting are formed, and a key groove 18a is formed in a part of the hole. Further, the outer periphery has four salient poles 18b, and there is a slot 18c for inserting a field magnet into the base of each salient pole.

FIG. 2 is an exploded perspective view showing the structure of the rotor 16. The rotor 16 is the slot 1 of the rotor yoke 18.
Four field magnets 19 are inserted in 8c so that the magnetic poles of the adjacent salient poles are reversed.

Referring to FIG.

Since the field magnet 19 is attached to the slot 18c by the magnetic force, it may move in the axial direction and fall out of the slot 18c due to vibration during operation of the motor. In order to prevent this, disks 11 and 14 are attached to both ends of the rotor 16, and these three parts are fastened to the shaft 17 by tightening the lock nuts 20.
The discs 11 and 14 have a shaft and a hole for loose fitting in the center, and the outer diameter is substantially the same as the outermost diameter of the rotor. The material is nonmagnetic. An encoder magnet 12 used for detecting the position of the rotor is incorporated in one of the discs 11. A state in which the disks 11, 14 and the rotor 16 are fixed to the shaft 17 by the loosening prevention nut 20 will be described with reference to FIG. FIG. 5 is a vertical cross-sectional view of a shaft and a rotor, showing a fixing structure of an encoder magnet according to the present invention. The disk 11 is the encoder magnet 1
2 is directed to the rotor 16 side. Therefore, all surfaces of the encoder magnet 12 are the disk 11 or the rotor 16
Covered with. Further, the field magnet 19 includes the disk 11,
It is designed so as not to be displaced in the axial direction by 14.

The disk 11 and the encoder magnet 12 will be described with reference to FIG. FIG. 4 is a perspective view of the encoder magnet, the disk, and the magnetizing yoke.

The circular plate 11 is a circular plate made of a non-magnetic material such as aluminum, has a shaft 17 and a hole for loose fitting in the center, and the rotor 16 is formed in a part of the hole. Encoder magnet 12
A key groove 11a, which is also used for aligning the magnetizing yoke and the encoder magnet 12 when magnetized, is machined. The outer diameter is concentric with the hole and is substantially equal to the outermost diameter of the rotor. A ring-shaped groove 11b is formed between the inner and outer diameters so as to be concentric with the hole. There is no depth. A ring-shaped non-magnetized encoder magnet 12 is bonded to the groove 11b.

Except for the yoke 3a, the magnetizing yoke 3 is made of a non-magnetic material, and has a convex portion 3b which fits the inner diameter of the disk 11, and a key groove of the disk 11 is provided at one place of the convex portion. 11
A key 3c is attached to a. A coil is wound around the yoke 3a, and when a current is applied to the coil, the four poles can be magnetized so as to be reversed. Key 3c
The positional relationship between the yoke 3a and the yoke 3a in the circumferential direction is equal to the positional relationship in the circumferential direction between the key groove 16a of the rotor 16 and the four salient poles. Therefore, when the key groove 11a of the disk 11 is fitted into the key 3c and magnetized, the circumferential positional relationship between the key groove 11a of the disk 11 and the magnetic poles magnetized by the encoder magnet 12 is the key of the rotor 16 The circumferential positional relationship between the groove 16a and the four salient poles is equal.

The field magnet 19 of the present invention has the slot 18
The encoder magnet 1 is attached to the disc 11 that prevents
Even if the encoder magnet 12 adhered to the disc 11 is separated due to the structure incorporating 2, the encoder magnet 12 is held between the disc 11 and the rotor 16, so that the encoder magnet 12 is scattered in the motor. The motor can be prevented from being damaged. Further, since the disc 11 also serves as a cover for fixing the conventional encoder magnet, the number of parts can be reduced by one. Further, by incorporating one ring-shaped encoder magnet 12 into the disk 11 and magnetizing it by using the key groove 11a used for alignment with the rotor, the number of parts is smaller than in the conventional case, and the rotor is reduced. The circumferential position of the magnetic pole and the circumferential position of the magnetic pole of the encoder magnet can now be accurately matched.

[0019]

As described above, according to the present invention, a plurality of salient poles are provided on the outer circumference, and the base of each salient pole has a slot for inserting a field magnet, and the slot has a field magnet. In the brushless motor using the rotor to be inserted, the non-magnetic disk for preventing the field magnet from coming off also serves as the fixing of the encoder magnet, so that the number of parts can be reduced.

Further, the magnetic encoder is easy to manufacture,
Even if the encoder magnet is peeled off, it no longer scatters in the motor.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a component fixed to a shaft according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the configuration of a rotor according to an embodiment of the present invention.

FIG. 3 is a plan view of a rotor yoke according to an embodiment of the present invention.

FIG. 4 is a perspective view of an encoder magnet, a disk, and a magnetizing yoke according to an embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view around a shaft and a rotor, showing a fixing structure of an encoder magnet according to an embodiment of the present invention.

FIG. 6 is a view of a conventional encoder magnet and cover.

FIG. 7 is a vertical cross-sectional view around a shaft and a rotor, showing a conventional encoder magnet fixing structure.

[Explanation of symbols]

 11 disk 11a key groove 12 encoder magnet 14 disk 15 key 16 rotor 16a key groove 17 shaft 18 rotor yoke 19 field magnet 20 lock nut

Claims (3)

[Claims] 1. A rotor having an even number of salient poles on its outer periphery, a slot for inserting a field magnet into the base of each salient pole, and a field magnet inserted in the slot, and a field magnet. In a brushless motor having two discs that prevent the magnet from coming out of the slot, and an encoder magnet, the encoder magnet is incorporated in one of the discs that prevents the field magnet from coming out of the slot. Encoder magnet fixing structure characterized by covering all surfaces of the disk with a disk or rotor. 2. An encoder magnet for a brushless motor, wherein one ring-shaped permanent magnet is used. 3. An encoder magnet, wherein one ring-shaped permanent magnet is fixed to a cover holding the magnet and then magnetized together with the position of the magnetic pole of the rotor.