JP2002058180A - Rotating electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating elastic machine which can reduce electromagnetic noise and vibrations, while complicated construction, increase in the number of components and assembly man-hours and the increase of material costs can be avoided. SOLUTION: Teeth 10 of the armature core 6 facing a plurality of salient field poles 2 have tips 100 facing radially the tips of the salient field poles 2 with a prescribed gap G. The rear of the top 100 of each tooth 10 in a rotation direction relative to the field core has a tapered plane 103, whose distance from the tip of the salient field pole 2 is increased radially, toward the rear in the relative rotation direction. As a result of such a constitution, electromagnetic noise can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for reducing electromagnetic noise and vibration of a rotating electric machine.

[0002]

2. Description of the Related Art In order to reduce electromagnetic noise and vibration of a rotating electric machine, Japanese Patent Application Laid-Open No. H06-225485 discloses that a stator is supported on a housing via a vibration isolator made of rubber elastic material. Japanese Patent Laid-Open No. 10-322939 discloses that a grain-oriented electrical steel sheet is used as an armature core.

[0003]

However, the adoption of the vibration-proof material increases the complexity of the structure and increases the material cost because a rubber material as the vibration-proof material requires a material having excellent heat resistance. However, it has not been easy to adopt it because there are problems such as deterioration in heat transfer cooling of the armature core.

[0004] Also, since grain-oriented electrical steel sheets are expensive,
Recruitment was not a consideration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a problem in that the structure is complicated, the number of parts and the number of steps are increased,
It is an object of the present invention to provide a rotating electric machine that can reduce electromagnetic noise and vibration while avoiding an increase in material costs.

[0006]

According to a first aspect of the present invention, there is provided a field core having a plurality of salient pole type field poles alternately arranged at a predetermined pitch in the circumferential direction, and a radial direction at a predetermined pitch in the circumferential direction. Armature core having a large number of teeth protruded,
In the rotating electrical machine having a tip surface that can face in a radial direction with a predetermined gap from a tip surface of the salient pole type field pole, the teeth may have at least one of the tip surfaces of the teeth relative to the field iron core. The rear end portion in the rotation direction is formed at a position farther from the front end surface of the salient pole type field pole than the front end portion.

[0007] According to this configuration, the tooth vibration and the electromagnetic noise caused by the tooth vibration can be reduced, and a quiet rotating electric machine can be realized. According to this configuration, an electromagnetic noise spectrum having a strong peak intensity in a specific narrow band in a particularly unpleasant high-sensitivity audible band can be suppressed satisfactorily. Also,
This configuration does not require a complicated structure and process compared to the conventional electromagnetic noise reduction technology having many of the above-mentioned problems such as rubber elastic materials, and can minimize the modification of existing manufacturing equipment. It also has the convenience.

According to a second aspect of the present invention, in the rotary electric machine according to the first aspect, further, a rear portion of the tooth tip surface in the direction of relative rotation with respect to the field iron core moves rearward in the direction of relative rotation of the tooth. Has a tapered surface portion that gradually moves away from the tip end surface of the salient pole type field pole in the radial direction.

According to this configuration, the tooth vibration and the electromagnetic noise caused by the tooth vibration can be further reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples.

[0011]

1 and 2 show an embodiment of a rotating electric machine to which the present invention is applied. FIG. 1 is a schematic axial sectional view of the rotary electric machine, and FIG. 2 is a front view of a field core and an armature core.

This rotating electric machine is a brushless DC motor having an outer rotor structure, wherein 1 is an outer rotor drum forming a yoke of a field iron core, 2 is a salient pole type field pole, 3 is a shaft, 4 and 5 are bearings, and 6 is a stator. A housing, 7 is a stopper, 8 is an armature core, and 9 is an armature coil.

The salient pole type field pole 2 is made of a permanent magnet whose opposing surface forms a magnetic pole surface, and is fixed alternately at a predetermined pitch in the circumferential direction to the inner peripheral surface of the outer rotor drum 1 at the rear end opening. I have. The outer rotor drum 1 is fixed to a shaft 3, and the shaft 3 is rotatably supported on the inner peripheral surface of a cylindrical portion of the stator housing 6 via bearings 4, 5. The stator housing 6 has a flange shape, and a flange extending radially outward from the rear end of the cylindrical portion is fixed to a frame (not shown). An armature core 8 is fitted and fixed to the cylindrical portion of the stator housing 6.

The armature core 8 is formed by laminating non-oriented electrical steel sheets in the axial direction, and the outer peripheral surface of the armature core 8 is formed in a radial direction with a small gap interposed between the radially inner end surfaces of the salient pole type field poles 2. Face to face. The outer peripheral surface of the armature core 8 is provided with a number of teeth 10 projecting radially outward at a predetermined pitch in the circumferential direction.
It is wound around the slot 11 between them.

Similarly to a normal brushless DC motor, the magnitude and phase of a current or a voltage applied to the three-phase armature coil 9 are controlled based on a signal detected by a rotation angle position detection sensor (not shown). As a result, the outer rotor drum 1 and the salient pole type field pole 2 fixed thereto rotate.

(Tee Shape) Next, the shape of the tooth 10 which characterizes the present invention will be described with reference to FIG. 3, and the shape of a conventional tooth 20 is shown in FIG. 4 for comparison.

In FIG. 3, reference numeral 100 denotes a tip end surface of the tooth 10 which faces the tip end surface of the salient pole type field pole 2 so as to be relatively rotatable across a gap G. A is the rotation direction of the outer rotor drum 1.

The front end surface 100 of the tooth 10 is located at the rear end (the tooth 1) in the rotation direction A of the outer rotor drum 1.
0 (front end in the relative rotation direction of 0) 101,
The outer rotor drum 1 has a tapered surface portion 103 that gradually moves radially inward from the front end surface of the salient pole type magnetic field pole 2 toward the front end (rear end in the relative rotation direction of the teeth 10) 102 in the rotation direction A of the outer rotor drum 1.

In this embodiment, the circumferential occupation angle of the tapered surface portion 103 as viewed from the axis is 80% of the circumferential occupation angle of the teeth 10, but can be appropriately selected within the range of 20 to 90%. . The taper inclination of the tapered surface portion 103 defined by the width of the gap G was set to 0 mm at the base end of the tapered surface portion 103 and 0.5 mm at the terminal end 102. When the taper inclination is defined by the width of the gap G at the terminal end 102, the tip surface 100 of the tooth 10 having no taper is used.
When the gap G at the rear end in the rotation direction A of the outer rotor drum 1 is 100%,
% Is preferable. If the taper inclination amount is smaller than this range, the effect of reducing electromagnetic noise is small, and if it is larger than this range, the exciting current component in the armature current component increases and the no-load loss undesirably increases.

(Electromagnetic noise reduction action)
It has been found that by providing the tapered surface portion 103 on the front surface 100 of the motor 0, the motor noise, particularly the spike-like noise spectrum in the 400-600 Hz band, which is unpleasant, can be reduced as shown in FIGS. FIG. 5 shows a motor noise spectrum of a rotary electric machine having the tooth 10 of this embodiment shown in FIG. 3, and FIG. 6 shows a conventional tooth 200 having no tapered surface portion 103 (the tip surface is a cylindrical surface) shown in FIG. Fig. 4 shows a motor noise spectrum of a rotating electric machine having. as a result,
It has been found that the 18th-order component (450 Hz) and the 36th-order component (900 Hz) of the rotation fundamental frequency can be greatly reduced.

By the way, the experimental data of the two rotating electric machines are shown in the following. The number of salient pole type field poles 2 is 6, and the circumferential occupation angle of the salient pole type field poles 2 as viewed from the axis is 51 ° (2π around the circumference). ), The diameter of the tip end surface of the salient pole type field pole 2 is 73 mm, the width of the gap G at a portion other than the tapered surface portion 103 is 0.8 mm, the number of the teeth 10 is 18, and the teeth 10 are occupied in the circumferential direction as viewed from the axis. The angle is 8 ° (the entire circumference is 2π), the axial length of the tip surface 100 of the teeth 10 is 18 mm, the number of revolutions is 1500 rpm, the number of conductors in the slot is 18, and the average armature current of each armature coil is 5
A, Loaded operation. Teeth 10 in the example product
The shape of the tapered surface portion 103 of the distal end surface 100 is as described above.

The reason why the electromagnetic noise can be reduced by providing the tapered surface portion 103 on the tip end surface 100 of the tooth 10 will be analyzed below with reference to FIG.

Electromagnetic noise is caused by a change in magnetic flux density of each part of the iron core. Due to the armature current in the slot, a magnetic flux (hereinafter also referred to as a current magnetic flux) Φi
Is formed.

When the teeth 10 move rightward relative to the salient pole type field poles 2, an electromotive force is generated in a downward direction by Fleming's right hand rule. Then, an eddy current is generated upward, and an eddy current magnetic flux Φe is generated around the eddy current according to the right thumb rule. The eddy current magnetic flux Φe has a direction of increasing the current magnetic flux Φi on the front end side in the rotation direction of the salient pole type field pole 2 and decreasing it on the rear end side. As a result, the magnetic flux density of the tip end surface 100 of the tooth 10
Increases on the rear end side in the relative rotation direction and decreases on the front end side.

After all, the tip surface 10 of the tooth 10
Magnetic flux density of 0 (composite magnetic flux of current flux and eddy current flux)
Has a large peak at the rear end side in the relative rotation direction of the teeth 10, and such a magnetic flux concentration of the teeth 10 increases the time variation of the torque of the salient pole type field pole 2 crossing this peak in the circumferential direction.

An actual measurement result of the circumferential variation of the magnetic flux distribution on the tip surface 100 of the tooth 10 will be described with reference to FIGS. FIG. 8 shows the measurement results of the example product having the tapered surface portion 103, and FIG.
0 is the same type as that of FIG. 0 and has no tapered surface portion 103). 8 and 9, a is a circumferential length from the tip of the tooth 10 or 20 in the salient pole type field pole rotation direction (the rear end in the relative rotation direction of the tooth) to the tip surface (100 in the case of the tooth 10) of the tooth 10 or 20. 20% of
The magnetic flux density, b, of the portion up to the tip of the teeth 10 or 20 (the rear end in the relative rotation direction of the teeth) from the salient pole type field pole rotation direction end of the teeth 10 or 20 (the tooth 10
100), the magnetic flux density at a portion of 20 to 40% of the circumferential length of c), c is from the tip of the teeth 10 or 20 in the salient pole type field pole rotation direction (the rear end in the relative rotation direction of the teeth) to the teeth 1
The magnetic flux density, d, of the portion of 40 to 60% of the circumferential length of the tip surface of 0 or 20 (100 in the case of the tooth 10) is the tip of the tooth 10 or 20 in the salient pole type field pole rotation direction (after the relative rotation direction of the tooth). 60 to 80% of the circumferential length from the end) to the tip surface of tooth 10 or 20 (100 in tooth 10)
Is the magnetic flux density of the portion, e is the tip of the teeth 10 or 20 in the salient pole type field pole rotation direction (the rear end in the relative rotation direction of the teeth).
To 80 to 100% of the circumferential length of the distal end surface of the tooth 10 or 20 (100 in the case of the tooth 10).

The distal end face 100 of the tooth 10 is
Divided into two partial surfaces 101 to 105
The magnetic flux density of No. 105 was measured. The measurement conditions were the same as the above specifications. However, regarding the influence of the field magnetic field of the salient pole type field pole 2, the above-described magnetic flux density measurement was performed in a state where the salient pole type field pole 2 was not magnetized. Note that the measurement was performed by attaching a search coil to each of the partial surfaces 101 to 105 individually.

As can be seen from FIG. 8 and FIG.
The teeth 2 having the same shape without the tapered surface 103 are provided by forming the tapered surface 103
Compared with 00, the variation in the magnetic flux density in the circumferential direction of the distal end surface 100 of the tooth 10 is significantly reduced.

The teeth 10 used in FIGS.
20 has a groove 300 extending in the axial direction at the center in the circumferential direction of the distal end surface. Even when the groove 300 is not provided, the result is almost the same. (Modification) In the above embodiment, a DC brushless motor has been described as an example. However, a DC motor or a generator having the same structure as those may be used.

[Brief description of the drawings]

FIG. 1 is a schematic axial sectional view of a rotating electric machine according to an embodiment.

FIG. 2 is a front view of a field core and an armature core of the rotary electric machine of FIG. 1;

FIG. 3 is a partially enlarged front view showing the shape of the teeth shown in FIG. 2;

FIG. 4 is a partially enlarged front view showing the shape of a conventional taperless tooth.

FIG. 5 is a spectrum diagram of motor noise of a rotating electric machine using the tapered teeth of FIG. 3;

6 is a spectrum diagram of motor noise of a rotating electric machine using the taperless teeth of FIG.

FIG. 7 is a schematic partial perspective view showing eddy currents of teeth rotating relative to salient pole type field poles.

FIG. 8 is a timing chart showing a temporal change of a magnetic flux density at each part of a tip end surface of a tapered tooth.

FIG. 9 is a timing chart showing a temporal change of a magnetic flux density of each part of the tip end surface of the taperless tooth.

[Explanation of symbols]

 2 Salient pole type field pole 8 Armature iron core 10 Teeth 100 Teeth tip surface 103 Tapered surface portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Yamada 14 Iwatani, Shimowakakucho, Nishio City, Aichi Prefecture Inside the Japan Auto Parts Research Institute (72) Inventor Kenji Takeda 14 Iwatani, Shimowakakucho, Nishio City, Aichi Prefecture Shares Inside the Japan Auto Parts Research Institute (72) Inventor Hideaki Suzuki 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside DENSO Corporation (72) Inventor Masao Ichikawa 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Co., Ltd. F term in DENSO (reference) 5H002 AA04 AA09 AB05 AB07 AB08 AC04 AC06 5H621 AA04 BB07 GA01 GA04 GA14 GA15 GA16 HH01 HH09 JK02 JK05 5H622 AA03 CA02 CA05 CA10 PP05 PP19

Claims (2)

[Claims] 1. An armature having a field iron core having a plurality of salient pole type field poles alternately arranged at a predetermined pitch in the circumferential direction and a number of teeth projecting radially at a predetermined pitch in the circumferential direction. A rotary electric machine having an iron core, wherein the teeth have a tip face that can face in a radial direction with a predetermined gap from a tip face of the salient pole type field pole; A rotating electric machine wherein a rear end in a direction of rotation relative to the field core is formed at a position farther from a front end of the salient pole type field pole than a front end. 2. The rotating electric machine according to claim 1, wherein a rear portion of a tip end surface of the tooth in a relative rotation direction with respect to the field iron core moves rearward in the relative rotation direction of the tooth to form the salient pole type field pole. A rotating electrical machine having a tapered surface portion that gradually moves away from a tip end surface in a radial direction.