JP2003319576A - Stator for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deformation of teeth and reduce vibration of an entire motor. <P>SOLUTION: A stator 3 for the motor includes a plurality of the teeth 32 that have coils wound and are parabolically projected and formed in an inward radial direction from an outer periphery 31, so that the teeth may face a rotor 10 with a plurality of magnets 1 disposed on the outer periphery, wherein a root 321 connected to the outer periphery 31 of the teeth 32 is larger in width than other portions. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of coils formed by radially projecting radially outward from the outer peripheral portion so as to face a rotor having a plurality of magnets arranged on the outer peripheral portion. The present invention relates to a motor stator having a tooth portion.

[0002]

2. Description of the Related Art The structure of a conventional motor is shown in FIGS. As shown in this figure, the magnet M is attached to the outer peripheral portion of the rotor R.
Are arranged at equal intervals. The magnets M are arranged so that the directions of their magnetic poles alternate. A large number of teeth T are arranged on an outer peripheral portion O facing the housing H of the motor stator, and the tips of the teeth T are magnets M.
Is facing. A winding (not shown) through which a current flows is wound around each tooth, and an electromagnetic force is generated in the tooth by the current flowing through this winding. The attractive force / repulsive force generated between the electromagnetic force and the magnet M causes the rotor R to rotate.

In general, it is considered that the width of the tooth is preferably as thin as possible within a range where magnetic saturation does not occur because many windings are wound in a small space. Further, the conventional tooth has a substantially constant width from the portion TO connected to the outer peripheral portion O to the portion TS of the tip portion connected to the wide tip portion TW.

[0004]

The motor having such a structure has a problem that vibration occurs when the motor rotates. When the motor vibrates, noise is generated, which causes noise. Particularly in the case of a motor mounted in a vehicle, vibration of the motor is transmitted to the frame of the vehicle body, and an unpleasant sound reaches the ears of the driver, which causes discomfort. Further, in the case of a power assisting motor for steering, vibration of the motor is felt through the steering, which also causes a driver discomfort.

The present inventors have diligently studied from various angles to solve this problem. In FIG. 10, a pair of magnets whose S poles and N poles face the teeth are teeth (1),
It is a measurement of the forces received in the r and t directions when approaching and separating from (2) and (3). In this figure, the electrical angle when the pair of magnets passes is represented by 0 to 360 ° on the horizontal axis. From the results of this experiment, the inventors
Was displaced by the change in the force received from the magnet M, and as a result, vibration was generated in the motor, and a supporting experiment was conducted. In this supporting experiment, the motor is rotated at a predetermined rotation frequency, and the correlation between the frequency of the current flowing through the winding and the vibration waveform generated in the motor at that time is measured. Frequency analysis of the vibration waveform of the motor obtained from this experiment revealed that the vibration peaked in the band corresponding to the current frequency of the winding. Therefore, it is confirmed that the above assumption is correct. In particular, it was observed that the vibration was severe when the natural frequency of the teeth was close to the current frequency.

FIG. 9 shows the result of computer simulation of the displacement of the teeth portion. As can be seen from this figure, the tooth displacement is greatest when the center of the tooth is approximately at the center of the two magnets. From this result, it can be confirmed that the above assumption is correct.

From these results, the inventors have found that the vibration of the motor can be suppressed by increasing the rigidity of the tooth portion so that the natural frequency of the tooth portion is separated from the current frequency of the winding. The invention was made. As mentioned above, it is said that the width of the tooth should be as thin as possible within the range where magnetic saturation does not occur. In order to increase the rigidity of the teeth part, it is necessary to thicken a part or all of the teeth, but by doing this, it is possible to suppress the vibration of the motor. .

[0008]

The motor stator according to the present invention (the first invention according to claim 1) is radially inward from the outer peripheral portion so as to face a rotor having a plurality of magnets arranged on the outer peripheral portion. In a motor stator having a plurality of tooth portions that are formed to radially project toward a coil and are wound with a coil, the tooth portions are configured such that their natural frequencies deviate from the current frequency. is there.

In the motor stator of the present invention (the second invention described in claim 2), in the first invention, the width of the root portion connected to the outer peripheral portion of the teeth portion is at least the width of the other portion. It is bigger.

In the motor stator of the present invention (the third invention according to claim 3), in the first invention, the width of the entire tooth portion is set to be large so as to have sufficient strength. .

In the motor stator of the present invention (the fourth invention according to claim 4), in the third invention, the width on the root side connected to the outer peripheral portion of the teeth portion is gradually changed. It is chamfered.

In the motor stator of the present invention (the fifth invention according to claim 5), in the third invention, the width on the tip side connected to the wide tip portion of the teeth portion is gradually changed. Is chamfered.

The motor stator of the present invention (sixth invention according to claim 6) is the motor stator according to any one of the first invention to the fifth invention, wherein the natural frequency of the teeth portion is the maximum number of revolutions of the motor. It is at least twice the fundamental wave frequency of the current flowing through the coil when rotating.

In the motor stator of the present invention (seventh invention according to claim 7), in the third invention, the teeth portion is formed separately for each tooth, and is spliced to form the whole. It is the one.

[0015]

The motor stator according to the first aspect of the present invention having the above-described structure is formed so as to radially project inward from the outer peripheral portion so as to face a rotor having a plurality of magnets arranged on the outer peripheral portion. In the motor stator having a plurality of teeth around which the coil is wound, the teeth are formed by a shape having rigidity such that the natural frequency thereof deviates from the current frequency. This has the effect of suppressing and reducing the vibration of the entire motor.

In the motor stator according to the second aspect of the invention having the above structure, in the first aspect of the invention, the width of the root portion connected to the outer peripheral portion of the tooth portion is greater than the width of at least the other portion, and thus is the largest. Since the rigidity of the root portion on which the stress acts is increased, it is possible to suppress the deformation of the teeth portion and reduce the vibration of the entire motor.

In the motor stator of the third aspect of the invention having the above structure, in the first aspect of the invention, since the width of the entire tooth portion is set to be large so as to have sufficient strength, the rigidity of the entire tooth portion is increased. In order to increase the height, it is possible to suppress the deformation of the teeth portion and reduce the vibration of the entire motor.

In the motor stator according to the fourth aspect of the present invention having the above structure, in the third aspect of the invention, chamfering is performed so that the width of the root side of the tooth portion connected to the outer peripheral portion gradually changes. Therefore, there is an effect that stress concentration on the root side of the teeth portion is relaxed.

In the motor stator according to the fifth aspect of the present invention having the above-mentioned structure, in the third aspect of the invention, chamfering is performed so that the width on the tip end side connected to the wide tip end portion of the tooth portion gradually changes. Therefore, there is an effect that stress concentration on the tip end side of the teeth portion is relaxed.

The motor stator according to a sixth aspect of the present invention having the above-mentioned structure is the motor stator according to any one of the first aspect to the fifth aspect, wherein the coil is used when the motor rotates at a natural frequency of the teeth portion which is the maximum number of revolutions. Since it is more than twice the fundamental frequency of the current flowing through the motor, the vibration of the teeth portion can be almost completely suppressed when the motor rotates at any rotation speed within its specification range.

In the motor stator of the seventh invention having the above-mentioned structure, in the third invention, the teeth portion is formed by being divided for each tooth, and the teeth are jointed to form the entire structure. It has the effect of having a high degree of freedom.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be described below.
This will be described with reference to the drawings.

(First Embodiment) The motor stator according to the first embodiment of the present invention has an outer peripheral portion facing the rotor 10 having a plurality of magnets 1 arranged on the outer peripheral portion as shown in FIGS. In the motor stator 3 including a plurality of teeth portions 32 radially formed inwardly protruding from the teeth 31 and around which the coil 5 is wound, a root portion 321 connected to the outer peripheral portion 31 of the teeth portion 32. Is larger than the width of other parts.

The motor 20 using the motor stator of the first embodiment is applied to an electric power steering apparatus as an example. As shown in FIGS. 2 and 3, the electric power steering apparatus 40 includes a rack housing 11, a tube yoke housing 13 coaxially attached to an end of the rack housing 11, and the tube yoke housing 13. And an end housing 14 coaxially attached to the end portion.

Each of these three housings is hollow and formed in a substantially cylindrical shape, and the rack shaft 12 is inserted into the inside thereof. The rotor 1 is mounted on the tube yoke housing 13 via bearings 17 and 30.
A hollow motor shaft made of iron (0) is rotatably inserted.

A ball screw nut 16 is fixed to the motor shaft 10, and a rack shaft 12 is coupled via the ball screw nut 16 so as to be movable in the axial direction. Tie rods 19 connected to the steered wheels via ball joints 18 are connected to both ends of the rack shaft 12, respectively.

As shown in FIG. 3, the tube yoke housing 13 has a motor 20 mounted therein, and the motor 20 has a motor shaft 10 as a rotating shaft inserted therein.

The motor 20 comprises an armature core as the motor stator 3 fixed to the inner peripheral surface of the tube yoke housing 13 and a ring magnet as the magnet 1 bonded to the outer peripheral surface of the motor shaft 10. ing. That is, the motor shaft 10 forms a magnetic path.

The motor stator 3 as the armature core is
As shown in FIGS. 1 and 3, a large number of iron cores are laminated, and an outer peripheral portion 31 facing the tube yoke housing 13 and an electric machine formed to radially project inward from the outer peripheral portion 31 are formed. Coil 5 as a child winding
And a plurality of teeth portions 32 around which is wound.

A wide T-shaped tip portion 322 is formed at the tip of the tooth portion 32 so as to face a rotor magnet as the magnet 1 bonded to the outer peripheral surface of the motor shaft 10.

The teeth portion 32 is formed in a substantially V shape with the widths on both sides of the root portion 321 connected to the outer peripheral portion 31 linearly increasing, and the outer peripheral portion 3 is formed from the width of other portions.
The closer it is to 1, the larger it is.

The motor stator of the first embodiment described above is
A plurality of teeth portions 32 are formed so as to radially protrude inward from the outer peripheral portion 31 so as to face the rotor 10 in which a plurality of magnets 1 are arranged on the outer peripheral portion, and the coils 5 are wound around the teeth portions 32. In the motor stator 3, since the width of the substantially V-shaped root portion 321 connected to the outer peripheral portion 31 of the motor stator 3 of the tooth portion 32 is at least larger than the width of other portions, the largest stress is exerted. Since the rigidity of the acting root portion 321 is increased, the tooth portion 3 is
The effect of suppressing the deformation of No. 2 and reducing the vibration of the entire motor is obtained.

Further, in order to suppress the vibration of the teeth portion 32 almost completely in all usage situations, the natural frequency of the teeth portion 32 is applied to the coil 5 when rotating at the maximum rotation speed of the motor 20. It is preferable that the frequency is at least twice the fundamental frequency of the flowing current. As described above, the vibration of the teeth portion 32 is caused by the radial and circumferential attraction / repulsion generated between the electromagnetic force generated by the current flowing through the coil 5 and the magnet 1. Therefore, the teeth portion 32 receives a force in the radial direction and a force in the circumferential direction that change in a cycle according to the fundamental wave frequency of the current flowing in the coil 5. By increasing the rigidity of the teeth portion 32 and increasing the natural frequency, resonance of the teeth portion 32 due to this periodically changing force can be suppressed, and in particular,
If the fundamental wave frequency of the current flowing through the coil 5 when the motor 20 rotates at the maximum rotation speed is twice or more,
The vibration can be suppressed almost completely in all usage situations of the motor 20. This also applies to other embodiments described later.

(Second Embodiment) In the motor stator of the second embodiment, as shown in FIG. 4, the entire width of the tooth portion 32 is set to be large so as to have sufficient strength as compared with the conventional one. The difference is the difference, and the difference will be mainly described below.

As shown in FIG. 4, the teeth portion 32 has a wide width facing the rotor magnet as the magnet 1 bonded to the outer peripheral surface of the motor shaft 10 from the root portion 321 connected to the outer peripheral portion 31. Almost T-shaped tip 3
The width of the tooth portion of all the parts up to 22 is uniformly increased as compared with the width of the conventional tooth portion indicated by the two-dot chain line.

The outer peripheral portion 31 of the motor stator 3 connected to the root portion 321 of the tooth portion 32.
The width in the radial direction is also uniformly increased as compared with the width of the conventional tooth portion indicated by the two-dot chain line.

In the motor stator of the second embodiment having the above structure, the overall width of the teeth portion 32 is set large so as to have sufficient strength, so that the rigidity of the entire teeth portion 32 is improved. In order to increase the height, it is possible to suppress the deformation of the teeth portion and reduce the vibration of the entire motor.

That is, since the entire width of the tooth portion 32 is set to be large and the rigidity of the entire tooth portion 32 is increased, the natural frequency of the tooth portion 32 is set to deviate from the current frequency. And the vibration of the entire motor is reduced.

The motor stator of the second embodiment is
The radial width of the outer peripheral portion 31 of the motor stator connected to the root portion 321 of the tooth portion 32 is also set to be sufficiently larger than the width of the conventional tooth portion indicated by a two-dot chain line. Therefore, the rigidity of the outer peripheral portion 31 as the base portion that supports the tooth portion 32 is increased, so that the vibration and deformation of the tooth portion 32 are effectively suppressed, and the conventional tooth shown in FIG. The vibration and deformation of the portion T are suppressed.

(Third Embodiment) In the motor stator of the third embodiment, as shown in FIG. 6, the width of the root side 321 connected to the outer peripheral portion 31 of the motor stator 3 of the tooth portion is gradually changed. The difference is that the chamfering is performed so that the width of the tip side 323 connected to the wide tip portion 322 of the tooth portion 32 is chamfered so as to gradually change. The following description focuses on the differences.

The motor stator of the third embodiment is 14
The tooth portion 32 is formed of a multi-divided stator having 12 poles, and the tooth portion 32 is formed by being divided for each tooth. By using the winding wire formed for each tooth and the circular hole 311 for fixing a jig during circular assembly By engaging the semicircular irregularities 312 and 313 at both ends of the outer peripheral portion, the whole is configured by joining them together.

In the motor stator of the third embodiment, the outer peripheral portion 3 of the motor stator 3 of the tooth portion 32 is used.
Since the width of the root side 321 connected to No. 1 is chamfered so as to gradually change, stress concentration on the root side 321 of the tooth portion 32 is relieved and the width of the tooth portion 32 is increased. Since the width of the tip end side 323 connected to the tip end portion 322 is chamfered so as to gradually change, the stress concentration on the tip end side 323 of the tooth portion 32 is mitigated.

The motor stator of the third embodiment is
Since the tooth portion 32 is formed by being divided for each tooth, and the projections and depressions 312 and 313 are engaged with each other and joined together, there is an effect that the degree of freedom in manufacturing is high.

The embodiments described above are merely examples for the purpose of explanation, and the present invention is not limited to them. Those skilled in the art will recognize from the claims, the detailed description of the invention and the description of the drawings. Modifications and additions can be made without departing from the technical idea of the present invention.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a main part of a motor stator according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway sectional view showing an electric power steering apparatus to which the motor of the first embodiment is applied.

FIG. 3 is a partially enlarged cross-sectional view showing a motor section of the electric power steering apparatus to which the first embodiment is applied.

FIG. 4 is a partial cross-sectional view showing a main part of a motor stator according to a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing a main part of a conventional motor stator.

FIG. 6 is a partial cross-sectional view showing a main part of a motor stator according to a third embodiment of the present invention.

FIG. 7 is a partial cross-sectional view showing a main part of a conventional motor stator.

FIG. 8 is an overall sectional view showing an entire conventional motor stator.

FIG. 9 is an overall cross-sectional view for explaining vibration deformation of a tooth portion in a conventional motor stator.

FIG. 10 is a diagram showing a relationship between an electrical angle and a tangential force and a radial force acting on a tooth portion in a conventional motor stator.

[Explanation of symbols]

1 magnet 5 coils 10 rotor 31 outer periphery 32 Teeth 321 root

Claims (7)

[Claims] 1. A plurality of teeth portions are formed so as to radially protrude inward from the outer peripheral portion so as to face a rotor having a plurality of magnets arranged on the outer peripheral portion, and the coils are wound around the teeth. In the motor stator, the tooth portion is formed in a shape such that its natural frequency deviates from the current frequency. 2. The motor stator according to claim 1, wherein a width of a root portion connected to the outer peripheral portion of the tooth portion is larger than a width of at least another portion. 3. The motor stator according to claim 1, wherein the entire width of the tooth portion is set large so as to have sufficient strength. 4. The motor stator according to claim 3, wherein chamfering is performed so that a width of a root side of the teeth portion connected to the outer peripheral portion gradually changes. 5. The motor stator according to claim 3, wherein chamfering is performed so that a width on the tip side connected to the wide tip portion of the tooth portion gradually changes. 6. The natural frequency of any one of claims 1 to 5, wherein the natural frequency of the teeth is at least twice the fundamental frequency of the current flowing through the coil when the motor rotates at the maximum speed. A motor stator characterized in that 7. The motor stator according to claim 3, wherein the tooth portion is formed by being divided for each tooth, and is spliced to form the whole.