JP2001069717A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attenuate vibration that occurs between a rotor and stator by an elastic material and to reduce vibration that is transmitted to a fixing part of a stator core by installing a stator core onto fixing part for the stator core via an elastic material. SOLUTION: In an electric motor (spindle motor) 10 that has an annular permanent magnet 12 and an armature 14 that is arranged inside the magnet 12, the magnet 12 is located on a rotor 16 and the armature 14 on the stator. Furthermore, the armature 14 is made up of a stator core 22 that is formed by laminating a plurality of core members and exciting coils 24 that are wound on each magnetic pole of the stator core 22. Here, the armature 14 is built on the outside circumference of a boss part (armature fixing part) via an annular elastic member 50. This structure enables the elastic member 50 to attenuate the vibration that may occur between the permanent magnet 12 and armature 14 when the electric motor 10 is driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor in which a stator core is coaxially arranged on a fixed portion.

[0002]

2. Description of the Related Art Generally, in a motor using permanent magnets such as a spindle motor, a ring-shaped permanent magnet is arranged on a rotor side, and an armature core is arranged on a stator side. The armature core, that is, the stator core, is firmly fixed to the fixed part for armature, such as the housing part and boss part of the stator, by press fitting, caulking, bonding, resin, etc. so as not to move with respect to the fixed part. Fixed.

[0003] When the rotor is rotated by the electromagnetic action between the permanent magnet on the rotor side and the armature on the stator side, the electromagnetic force generated by the exciting coil wound on the stator core and the magnetic force from the permanent magnet on the rotor side cause the rotation. , Commutation vibration generated by commutation, magnetic pole number vibration generated according to the number of magnetic poles of the permanent magnet, phase number vibration generated according to the number of AC phases used, generated according to the number of poles of the stator core The number of pole vibrations,
Many types of vibrations having frequencies ranging from several times to several tens times the basic rotation speed of the electric motor are generated.

It is presumed that the above-mentioned vibration is caused by the armature being firmly fixed to the armature fixing portion of the stator. For example, the thickness dimension of the adhesive layer or the resin layer is generally as very small as about 50 μm, and at such a thickness dimension, there is a great difference from the case where the armature is directly assembled to the armature fixing portion. Absent.

[0005] The occurrence of such vibrations adversely affects various characteristics required for the motor, such as accuracy, noise, vibration, and current. In particular, a spindle motor using a fluid dynamic pressure bearing using air or liquid as a bearing is susceptible to the above-described adverse effects because the shaft rigidity is lower than when a ball bearing is used.

[0006]

Therefore, in an electric motor such as a spindle motor, it is important to reduce vibration as much as possible.

[0007]

A motor according to the present invention has a stator core mounted on a stator core fixing portion via an elastic body.

The vibration generated between the rotor and the stator is attenuated by the elastic member disposed between the stator core and the fixed portion for the stator core, and the vibration transmitted to the fixed portion for the stator core is significantly reduced.

[0009] The fixed portion may be a boss on which the rotor is assembled by a bearing. Instead of this, the fixing part may be a housing part, and the stator core may be assembled to a holder mounted on the housing part via the elastic body.

In a preferred embodiment, the elastic body has an annular shape extending around the housing, and the stator core is mounted on the boss via the elastic body.

In another preferred embodiment, the stator core is mounted on the boss via the elastic body at one end or both ends in the direction of the rotation axis of the rotor.

In still another preferred embodiment, the stator further includes an annular holder having an L-shaped cross-sectional shape provided with a tubular portion and a flange portion connected to one end thereof, and the fixed portion is a housing portion. The holder is mounted on the housing via the elastic body at the flange portion, and the stator core is assembled to the tubular portion of the holder.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG.
Is a spindle motor using a ring-shaped permanent magnet 12 and an armature 14 disposed inside the permanent magnet 12, and a hard disk, a floppy disk, etc.
Used for driving a storage medium. The permanent magnet 12 is located on the rotor 18 and is rotated about a rotation axis 20. Armature 14 is arranged on stator 16.

The permanent magnet 12 includes a plurality of magnetic pole portions (not shown) magnetized in the radial direction of rotation of the rotor 18.
Have around 0. Magnetic pole portions adjacent to each other in the rotation direction of the rotor 18 are magnetized in the opposite direction. The inner surface of each magnetic pole
It acts as the pole face of the permanent magnet 12.

The armature 14 includes a stator core 22 formed by laminating a plurality of core members made of a thin metal plate such as a silicon steel plate.
And an exciting coil 24 wound around each magnetic pole portion of the core 22. Each pole face of the core 22 has a substantially rectangular shape in a developed state.

The stator 16 has a dish shape and serves as a mounting base. The stator 16 has a boss 26 in the center, a housing 28 around the boss 26, and a flange 30 on the outer periphery of the housing 28. Screwed into. The boss 26 has a space that opens upward.

The rotor 18 also has a dish shape. The rotor 18 has a shaft 32 received by the boss 26 at the center, a rotor hub 34 around the shaft 32, and an upwardly directed step 36 at the outer periphery of the rotor hub 34. The permanent magnet 12 is mounted inside the rotor 18 so as not to rotate relatively.

A ring 38 is attached to the shaft 32 so as not to rotate relatively. The ring 38 has a substantially rectangular cross-sectional shape, and includes the boss portion 26 and the boss portion 26.
Is received in an annular recess 42 formed by a ring-shaped auxiliary member 40 disposed at the upper part of the ring. The auxiliary member 40 is assembled to the boss portion 26 so as not to rotate relatively.

Both inner surfaces (upper and lower surfaces) of the recess 42 in the direction of the rotation axis 20 and corresponding two surfaces (upper and lower surfaces) of the ring 38.
Are defined as thrust dynamic pressure bearing regions 44 and 46, and between the inner bottom surface (inner peripheral surface) of the recess 42 and the outer peripheral surface of the ring 38 are defined as radial dynamic pressure bearing regions 48. These dynamic pressure bearing regions 44, 46, 48 are filled with a liquid such as lubricating oil.

The thrust dynamic pressure groove (not shown) is connected to the rotation axis 2
The inner surface of the recess 42 in the zero direction or the corresponding both surfaces of the ring 38 is formed, and the radial dynamic pressure grooves (not shown) are formed on the inner bottom surface of the recess 42 or the outer peripheral surface of the ring 38. I have.

In the illustrated example, the permanent magnet 12 is mounted coaxially on the inner surface of the rotor hub 34. On the other hand, the armature 14 has the boss 26
Are coaxially mounted on the outer periphery of the motor so as to be relatively non-rotatable.

The elastic body 50 is made of a material having a high elastic modulus, such as rubber, and a property capable of maintaining the position of the armature 14 to some extent. It is located between them. Elastic body 5
0 can be a rubber-based adhesive.

In use, one or more storage media, such as a hard disk, are placed over the upward step 36 of the rotor 18. When a driving current having a predetermined frequency is supplied to the exciting coil 24 of the armature 14 with a predetermined phase, the rotor 18 is rotated by the interaction between the rotating magnetic field formed by the armature 14 and the magnetic field from the permanent magnet 12. You.

When the electric motor 10 is rotated, the permanent magnet 12
Various vibrations occur between the permanent magnet 12 and the armature 14 (between the rotor 18 and the stator 16) due to the interaction between the armature 14 and the armature 14. However, in the electric motor 10, since the elastic body 50 is disposed between the core 22 of the armature 14 and the armature fixing portion (the boss portion 26 in the illustrated example) of the stator 16, the permanent magnet 12 Vibration generated between the armature 14 (between the rotor 18 and the stator 16) is attenuated by the elastic body 50 existing between the core 22 and the boss 26.

As a result, in the motor 10, the amount and level of vibration transmitted to the armature fixing portion of the stator 16 is significantly reduced. Further, the generation level of high-frequency vibration caused by attraction / repulsion acting between the permanent magnet 12 and the core 22 is significantly reduced.

Instead of assembling the core 22 to the boss portion 26 through the annular elastic body 50 disposed between the core 22 and the boss portion 26 as described above, the armature 14 is not connected to another elastic portion at another portion. It may be assembled to the armature fixing portion of the stator 16 by a body.

For example, as shown in FIG. 2, a space 52 is formed between the core 22 and the boss portion 26, and the core 22 is made of an elastic material such as silicone rubber at one end or both ends in the direction of the rotation axis 20. It may be assembled to the boss part 26 via 54. In this embodiment, since the armature 14 does not directly contact the boss portion 26, the same operation and effect as those of the embodiment shown in FIG.

As shown in FIG. 3, the core 22 is assembled to an annular holder 56 having an L-shaped cross section, and the holder 56 is connected to the housing 2 via a disc-shaped elastic body 58.
8 may be attached. In this embodiment, a space 60 is formed between the holder 56 and the boss portion 26, and the elastic body 58 is disposed between the holder 56 and the housing portion 28. Has the function and effect of

The thickness of the elastic bodies 50 and 58 is 0.2
mm to 5 mm, preferably about 0.2 mm to 1 mm. Spaces 52, 6 in the radius of rotation direction
The dimension of 0 can be an appropriate value as long as the armature 14 does not contact the boss portion 26 or the housing portion 28, and thus can be approximately the same as the thickness dimension of the elastic bodies 50 and 58, for example.

Instead of arranging the permanent magnet 12 outside the armature 14, the permanent magnet may be arranged inside the armature.

The present invention is not limited to the above embodiment. For example, the present invention can be applied not only to a torque motor but also to other electric motors. The present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electric motor according to the present invention.

FIG. 2 is a sectional view showing a left half of another embodiment of the electric motor according to the present invention.

FIG. 3 is a cross-sectional view showing a left half of still another embodiment of the electric motor according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electric motor (spindle motor) 12 Permanent magnet 14 Armature 16 Stator 18 Rotor 20 Rotation axis 22 Stator core 24 Exciting coil 26 Boss (armature fixed part) 28 Housing part (armature fixed part) 50, 54, 58 Elasticity Body 52, 60 Space 56 Holder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H002 AA04 AB08 AC04 5H605 AA04 BB05 BB19 CC03 DD09 EA09 EA19 5H607 AA04 BB01 BB09 BB14 CC01 CC05 DD01 FF12 JJ08

Claims (6)

[Claims] 1. An electric motor including a rotor and a stator, wherein the stator includes a stator core and a fixed portion to which the stator core is attached, and the stator core is mounted on the fixed portion via an elastic body. 2. The electric motor according to claim 1, wherein the fixed portion includes a boss on which the rotor is assembled by a bearing. 3. The electric motor according to claim 2, wherein the elastic body has an annular shape extending around the housing, and the stator core is mounted on the boss via the elastic body. . 4. The electric motor according to claim 2, wherein the stator core is mounted on the boss via the elastic body at one end or both ends in the direction of the rotation axis of the rotor. 5. The electric motor according to claim 1, wherein the fixing portion is a housing portion, and the stator core is assembled to a holder mounted on the housing portion via the elastic body. 6. The stator further includes an annular holder having an L-shaped cross-sectional shape including a cylindrical portion and a flange portion connected to one end thereof, wherein the fixing portion is a housing portion, and the holder is The electric motor according to claim 1, wherein the flange is mounted on the housing via the elastic body, and the stator core is assembled to the tubular portion of the holder.