JPH104664A - AC generator - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent adsorption and accumulation of magnetic metal pieces by a permanent magnet. SOLUTION: A plurality of claws 1 forming both poles of a rotor 10 are provided.
A plurality of permanent magnets 41 are arranged between 2 and 22. In addition, the fan 4 is provided at both ends of the rotor 10 in the axial direction.
8, 49 are arranged to create a flow of cooling air. According to this configuration, the magnetic metal piece can be flipped radially outward by the fan, and the chance of the magnetic metal piece reaching the rotor 10 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC generator provided with a magnet between magnetic poles, and is particularly suitable for a vehicle AC generator.

[0002]

2. Description of the Related Art In recent years, low noise and high output have been demanded as social needs for vehicle alternators. Here, as a technique for improving the output of the vehicle alternator, for example, a technology disclosed in Japanese Patent Application Laid-Open No. 61-85045, “Vehicle Alternator” is known.

[0003]

In the rotor of the automotive alternator disclosed in the above publication, an effective magnetic flux contributing to power generation is generated by a permanent magnet as an auxiliary magnet provided between the claw portions of a pole core serving as claw-shaped magnetic poles. In addition, the output can be improved, the physique can be reduced in size, and the like. However, in the conventional technology, since the rotor is equipped with the permanent magnet, the rotor is magnetized even when the power generation is stopped, and the magnetic metal pieces such as iron sand, iron pieces, and rust are attracted and held. there were. Such a magnetic metal piece may eventually cause rust, hinder the rotation of the rotor, or even degrade the electrical and magnetic characteristics. In particular, when the magnetic metal piece is separated from the rotor during rotation, there is a possibility that the magnetic metal piece may bite into a minute gap between the rotor and the stator, which may cause a problem such as a decrease in power generation performance and a rotation failure.

Conventionally, air-cooling structures have been often used in AC generators for vehicles, and a configuration is adopted in which cooling air is forcibly taken into the generator from outside the generator case and discharged. Have been. However, in the so-called external fan type, in which a cooling fan is placed outside the generator case and the air inside the generator case is sucked out from a specific opening in the generator case, after all the external air has passed through the generator, Since the magnetic metal pieces flow outward in the radial direction with the cooling fan, the magnetic metal pieces pass through the inside of the generator together with the external air, so that there is a problem that the magnetic metal pieces are easily attracted to the rotor.

[0005] The present invention has been made to solve the problems of the prior art. SUMMARY OF THE INVENTION An object of the present invention is to prevent a magnetic metal piece from attaching to a rotor having a permanent magnet due to the magnetic force of the permanent magnet.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an AC generator in which a rotor core is excited by a field coil. A permanent magnet that increases magnetic flux, and a fan that is arranged at an axial end of the rotor and generates a flow of cooling air that is introduced along a rotation axis of the rotor and that is directed radially outward. The technical means of the featured alternator is adopted.

According to such a configuration, the fan is disposed at the end of the rotor having the permanent magnet, and the cooling air introduced from the outside of the generator along the rotating shaft is discharged radially outward. Therefore, the magnetic metal pieces that are to enter together with the cooling air are repelled by the plurality of blades of the fan and are prevented from reaching the rotor. In particular, in an AC generator using a so-called external fan, the cooling air reaches the fan after passing through the inside of the generator, so the magnetic metal pieces can reach the rotor before being repelled by the fan and are absorbed by the rotor. However, according to the configuration of the present invention, there is an effect that the magnetic metal piece to be attached to the rotor can be flicked off before reaching the rotor.

Further, as in the second aspect of the present invention, a technical means may be adopted in which the fan is disposed at both axial ends of the rotor. According to such a configuration,
A cooling air flow introduced from both sides of the rotor shaft and discharged radially outward can be created, and the magnetic metal pieces entering through both paths are repelled by the fan blades of the fan. It can be skipped, and the accumulation of magnetic metal pieces can be more reliably prevented.

According to another aspect of the present invention, the permanent magnet includes a plurality of permanent magnets disposed between a plurality of magnetic poles formed on the core of the rotor. Means may be adopted. According to this configuration, it is possible to prevent the magnetic metal pieces from being attracted and accumulated by the plurality of permanent magnets arranged corresponding to the plurality of magnetic poles. In particular, a permanent magnet is provided between the magnetic pole facing the stator,
Even in a configuration in which a metal piece easily penetrates into a minute gap between the stator and the rotor, the metal piece can be prevented from entering.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on some examples. First, a first embodiment will be described. FIG. 1 is a longitudinal sectional view showing a configuration of a rotor of an automotive alternator according to the present invention, and FIG. 2 is a view showing a state where a pair of pole cores, a non-magnetic ring and a permanent magnet are assembled. It is a perspective view. FIG. 3 is a partial perspective view showing a nonmagnetic ring in which permanent magnets are disposed on the inner surface,
FIG. 4 is a partial vertical sectional view taken along the line IV-IV of FIG. The rotor 10 of the vehicle alternator mainly includes pole cores 11 and 21 as iron cores and the non-magnetic ring 3.
1, a permanent magnet 41 as an auxiliary magnet, a field coil 45 as electromagnetic exciting means, a shaft 46,
It is composed of fans 48 and 49.

The pole cores 11 and 21 are formed with a plurality of claw portions 12 and 22 which are claw-shaped magnetic poles protruding in the axial direction toward the outer periphery. The pole cores 11 and 21 have the claw portion 1
2, 22 are opposed to each other and are alternately positioned in the circumferential direction and are combined.
5, and is fitted and integrally assembled with a knurl provided on the shaft 46.

As shown in FIG. 4, the nonmagnetic ring 31 has a side surface 32 in contact with the side surfaces 13, 23 of the pawl portions 12, 22 of the pole cores 11, 21, and a bottom portion 33 thereof. , 22 are formed so as to be in contact with the inner side surfaces 14, 24, and to fill the space between the opposing claw portions 12, 22 and have the same outer diameter surface as the outer diameter surface of the claw portions 12, 22. .

On the inner surface 35 of the outer peripheral portion 34 of the nonmagnetic ring 31, a permanent magnet 41 is provided with a field coil 45.
And a gap. The permanent magnet 41 is magnetized so as to prevent a leakage magnetic flux between the magnetic poles of the claw portions 12 and 22 of the pole cores 11 and 21. As described above, the permanent magnet 41 is arranged between the claw portions 12 and 22 as the magnetic poles excited by the field coil 45, that is, in the leakage flux path of the magnetic flux supplied by the field coil 45.

On the surface of the permanent magnet 41, a plate-shaped non-magnetic ring 31 is arranged.
A side surface portion 32 of the non-magnetic ring 31 is disposed between the non-magnetic ring 31 and the claw portions 12 and 22, and an outer peripheral portion 34 of the non-magnetic ring 31 is disposed radially outside of the permanent magnet 41. 41 covers the outer surface in the radial direction. In addition, the nonmagnetic ring 31 is arranged such that the bottom 33 is in contact with the inner side surfaces 14, 24 of the claws 12, 22.
It is fixed to. For this reason, the outer peripheral portion 34 of the nonmagnetic ring 31 is disposed between the claws 12 and 22 and covers the radially outer side of the gap between the claws 12 and 22. The permanent magnet 41 is arranged radially inside the outer peripheral portion 34.

Further, in this embodiment, the permanent magnet 41 is wrapped radially outward and circumferentially by the non-magnetic ring 31. When the permanent magnet 41 is assembled to the pole cores 11 and 21, the outer peripheral portion 34 of the non-magnetic ring 31 is provided. The movement of the permanent magnet 41 to the outside in the radial direction is regulated by this. Therefore,
The permanent magnet 41 is fixed to the pole cores 11 and 21 via the non-magnetic ring 31.

The fans 48 and 49 are fixed to both ends of the rotor 10 in the axial direction. The fans 48 and 49 are configured by arranging a plurality of fan blades in a ring shape slightly inside the outer periphery of the rotor, and are introduced from both ends along the rotation axis of the rotor and are directed radially outward. This creates a flow of cooling air that is exhausted. Next, the operation will be described.

The magnetic flux generated by the field coil 45 passes through the pole cores 11 and 21 and is supplied to a stator (not shown) disposed close to the outer peripheral surfaces of the pole cores 11 and 21. 21 claws 12, 2
2 also flows as leakage magnetic flux. Here, since the permanent magnet 41 is disposed between the claw portions 12 and 22 of the pole cores 11 and 21, a part of the leakage magnetic flux can be utilized as an effective magnetic flux, and as a result, the leakage magnetic flux can be reduced. .

As a result, as shown in FIG. 5, the output current with respect to the rotation speed can be increased as compared with the case where the permanent magnet 41 is not disposed between the claw portions 12 and 22 of the pole cores 11 and 21. Further, since the fans 48 and 49 are arranged at both ends in the axial direction of the rotor 10, the magnetic metal pieces that are to enter from both ends in the axial direction are repelled,
The magnetic metal piece is prevented from reaching the rotor 10 and being attracted to the magnetic force of the permanent magnet 41.

Further, by using a plastic magnet for the permanent magnet 41, peeling and breakage of the magnet during and after assembly can be prevented. FIG.
FIG. 7 is a partial perspective view showing a second embodiment of the nonmagnetic ring and the like according to the present invention, and FIG. 7 is a partial longitudinal sectional view corresponding to FIG. 4 using the nonmagnetic ring of FIG. The components having the same functions as those of the above-described embodiment will be described with the same reference numerals.

The nonmagnetic ring 31 is formed of resin, and the permanent magnet 41 is insert-molded. That is, in this embodiment, all surfaces of the permanent magnet 41 are covered and protected by the nonmagnetic ring 31. here,
The pole cores 11 and 2 are attached to the outer peripheral portion 34 of the nonmagnetic ring 31.
When there is a portion larger than the outer diameter surface of the claw portions 12 and 22, the portion is cut or the like to minimize irregularities, and the outer diameter surface of the claw portions 12 and 22 is made substantially the same as the outer diameter surface. Thereby, the effect of reducing wind noise can be increased.

FIG. 8 is a partial sectional view showing a third embodiment of a non-magnetic ring or the like to which the present invention is applied. In the present embodiment, the permanent magnet 41 is disposed in direct contact with the claw portions 12 and 22 of the pole cores 11 and 21 so as to fill the gap between the side surfaces 13 and 23. The nonmagnetic ring 31 is provided with the claw portion 1.
2, 22 are formed so as to contact the side surfaces 13, 23 and the inner side surfaces 14, 24.

The non-magnetic ring 31 is provided with a spring effect so that the permanent magnet 41 is always sandwiched between the side surfaces 13 and 23 of the claw portions 12 and 22 while a pressing force is generated. With such a configuration, the same effect as in the above-described embodiment can be obtained. FIG. 9 is a partial longitudinal section showing a fourth embodiment of the nonmagnetic ring and the like according to the present invention.

When the non-magnetic ring 31 is formed of a non-magnetic metal body and the permanent magnet 41 is formed of a metal magnet, the permanent magnet 4 disposed on the inner surface 35 side of the non-magnetic ring 31 is used.
At least a part of the contact surface of the peripheral surface 1 with the nonmagnetic ring 31 is integrally formed with a buffer member 42 or an adhesive material interposed between the nonmagnetic ring 31 and the permanent magnet 41. There is no interference, and the same effect as in the above embodiment can be obtained. Thus, the non-magnetic ring 3
In addition to the above, the effect of protecting the magnet can be improved by interposing a buffer member or an adhesive.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a rotor of an automotive alternator according to a specific embodiment of the present invention.

FIG. 2 is a partial perspective view showing a state where a pair of pole cores, a nonmagnetic ring, and a permanent magnet are assembled.

FIG. 3 is a partial perspective view showing a nonmagnetic ring in which a permanent magnet is provided on an inner surface.

FIG. 4 is a partial longitudinal sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is an explanatory diagram showing a relationship between a rotation speed and an output current depending on the presence or absence of a permanent magnet.

FIG. 6 shows a second example of the nonmagnetic ring or the like according to the present invention.
FIG. 3 is a partial perspective view showing the embodiment of FIG.

FIG. 7 is a partial longitudinal sectional view corresponding to FIG. 4 using the nonmagnetic ring of FIG. 6;

FIG. 8 is a third view of a non-magnetic ring or the like according to the present invention;
FIG. 4 is a partial longitudinal sectional view showing the example of FIG.

FIG. 9 is a view showing a fourth example of the nonmagnetic ring and the like according to the present invention;
FIG. 4 is a partial longitudinal sectional view showing the example of FIG.

[Explanation of symbols]

 Reference Signs List 10 Rotor of vehicle alternator 11, 21 Pole core 12, 22 Claw (magnetic pole) 31 Nonmagnetic ring 41 Permanent magnet 45 Field coil 46 Shaft 48, 49 Fan

Claims (3)

[Claims] 1. An AC generator for exciting a rotor core with a field coil, a permanent magnet mounted on the rotor to increase an effective magnetic flux contributing to power generation, and an axial end of the rotor. And a fan that is arranged along the rotation axis of the rotor and generates a flow of cooling air that is introduced radially outwardly along the rotation axis of the rotor. 2. The alternator according to claim 1, wherein the fans are arranged at both ends in the axial direction of the rotor. 3. The permanent magnet according to claim 1, wherein the permanent magnet comprises a plurality of permanent magnets arranged between a plurality of magnetic poles formed on the core of the rotor. Alternator.