JPH08130851A - Axial gap motor - Google Patents

Abstract

PURPOSE: To fully restrict the movement of a rotor in axial direction by suppressing vibration during the rotation of the rotor. CONSTITUTION: A radial bearing 32 consisting of a dynamic pressure air bearing 31 formed at an outer peripheral portion of a rotating shaft 28 with a herringbone groove 31 and a bearing cylinder 23 is constituted with thrust bearings 36a and 36b comprising a dynamic pressure air bearing made of a stator base 22, a motor base 21 and a herringbone groove 33 formed on both the surfaces of a rotation york 30. However, a rotor 26 is supported in a rotatable manner by a stator 25 through a radial bearing 32 comprising the dynamic pressure air bearing and thrust bearings 36a and 36b, so that no contact portion is created during the rotation of the rotor 26 and thus the occurrence of vibration can be suppressed and further the motion of the rotor 26 in axial direction created by the radial bearing 32 caused by its construction as a dynamic pressure bearing can be fully restricted by thrust bearings 36a and 36b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor capable of coping with high speed operation.

[0002]

2. Description of the Related Art FIG. 6 shows the structure of a small precision motor conventionally mounted in, for example, a magnetic disk device or an optical disk device. In FIG. 6, the stator 1 has a tubular portion 3 in the center of the housing 2 and a plurality of armature coils 6 on the outside of the tubular portion 3 with a stator yoke 4 and a printed wiring board 5 interposed therebetween. The rotor 7 has a rotating shaft 9 in the center of a rotor yoke 8, and a field permanent magnet 10 axially opposed to the armature coil 6 outside the rotating shaft 9.
The rotary shaft 9 includes a radial bearing 1 including two rolling bearings arranged side by side in the cylindrical portion 3.
It is rotatably supported by 1a and 11b.

[0003]

However, in the above-mentioned conventional structure, the two radial bearings 11a, 1 are provided.
1b is a rolling bearing having a large number of spherical rolling elements between an outer ring and an inner ring. Since the rolling bearing 1b has a structure in which a contact portion is always generated when the rotor 7 rotates, there is a situation that vibration is likely to occur.

SUMMARY OF THE INVENTION An object of the present invention made in view of the above circumstances is, firstly, to provide an axial gap type motor capable of suppressing vibration during rotor rotation.
When a dynamic pressure bearing is used instead of the rolling bearing to achieve this purpose, there is a new problem that the rotor moves in the axial direction when the rotor rotates. Therefore, an object of the present invention is to provide an axial gap type motor which can suppress vibration during rotation of a rotor first, and secondly can sufficiently restrict axial movement of the rotor.

[0005]

SUMMARY OF THE INVENTION The present invention rotates a rotor having a stator having a plurality of armature coils arranged in a plane and a field permanent magnet axially opposed to the armature coils. In a possible arrangement, a rotating body is provided on the rotating shaft of the rotor so as to sandwich the armature coil between the permanent magnet and the permanent magnet, and the rotating body faces both sides of the rotating body or both sides of the rotating body. A dynamic pressure generating groove is provided on a stationary surface to form a thrust bearing composed of a dynamic pressure bearing, and a dynamic pressure generating groove is provided on either the rotary shaft or the inner surface of a bearing cylinder portion surrounding the rotary shaft. It is characterized by constituting a radial bearing consisting of (Claim 1).

In this case, the rotating body is preferably made of a magnetic material (claim 2). Further, it is preferable that the stator has an armature coil molded body in which a plurality of armature coils are integrally formed of resin, and a bearing is integrally formed on the inner diameter side of the resin portion (claim 3). The rotary shaft is extended to the side opposite to the armature coil of the rotary body, and the radial bearing having a dynamic pressure generating groove provided on either the rotary shaft or the inner surface of the bearing cylinder has two locations on both sides of the rotary body. (Claim 4).

[0007]

According to the means of claim 1, when the rotor is rotating, the dynamic pressure generating groove provided on either the rotary shaft or the inner surface of the bearing cylindrical portion surrounding the rotary shaft allows the rotary shaft and the bearing to be separated from each other. Dynamic pressure is generated in the air between them, and the rotating shaft is rotated in a non-contact state with the bearing. Further, since a dynamic pressure generating groove is provided on both surfaces of the rotating body or a stationary surface facing both sides of the rotating body to form a thrust bearing composed of a dynamic pressure bearing, movement in the axial direction is restricted.

According to the second aspect of the present invention, since the rotating body is made of a magnetic body, the rotating body also functions as a stator yoke to form a magnetic path and rotates integrally with the permanent magnet. Therefore, the eddy current generated in the rotating body is suppressed. Further, a magnetic attraction force acts between the permanent magnet and the rotating body, but since both are provided in the rotor,
The magnetic attraction force does not act on the thrust bearing as a thrust load.

According to the third aspect of the invention, since the bearing is integrated with the stator, the number of parts can be reduced and the assembly becomes easy. According to the means described in claim 4, since the radial bearing is composed of two places, the rotor can be supported more stably.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a spindle motor of a hard disk drive device will be described below with reference to FIG.
This will be described with reference to FIG. First, FIG. 1 showing the overall configuration.
In the above, at a peripheral portion of the plastic motor base 21, a plastic stator base 22 having a container shape with an open lower side is fixed so as to cover the motor base 21. A bearing cylinder 23 as a bearing is erected upright in the center of the stator base 22, and a plurality of armature coils 2 are positioned on the outer upper surface of the bearing cylinder 23.
4 are arranged in an annular shape at equal intervals, and are attached by, for example, bonding to form the stator 25.

The rotor 26 is mounted on the rotor yoke 27, a rotary shaft 28 fitted in the central portion of the rotor yoke 27 and rotatably inserted in the bearing cylinder 23, and attached to the inner surface of the rotor yoke 27 by, for example, bonding. It is composed of a child coil 24 and an annular permanent magnet 29 for field magnet which is opposed to the axial direction.

A rotating yoke 30 made of a magnetic material is attached as a rotating body to an end portion of the rotating shaft opposite to the rotor yoke 27 side, which functions as a stator yoke. The rotary yoke 30 is rotatably arranged between the motor base 21 and the stator base 22. The rotor yoke 27 is made of magnetic material such as stainless steel.

A herringbone groove 31, which is a dynamic pressure generating groove, is provided on the outer peripheral portion of the rotary shaft 28 facing the bearing cylinder 23, and the herringbone groove 31 and the bearing cylinder 23 constitute a dynamic pressure gas bearing. The radial bearing 32 is configured. Further, as shown in FIG. 2, a plurality of herringbone grooves 33, which are dynamic pressure generating grooves, are annularly provided on both surfaces of the rotary yoke 30 attached to the lower end of the rotary shaft 28. And the stationary surface 34 which is the inner surface of the motor base 21 and the stationary surface 35 which is the inner surface of the stator base 22 facing the herringbone groove 33 constitute thrust bearings 36a and 36b which are dynamic pressure gas bearings.
Thus, the rotor 26 is rotatably supported by the stator 25 via the radial bearing 32 and the thrust bearings 36a and 36b.

The operation of the above configuration will be described. The rotor 26 is generated based on the magnetic flux generated in the armature coil 24 and the magnetic flux generated by the permanent magnet 29 as the armature coil 24 is energized.
Is rotated. When the rotor 26 rotates, a dynamic pressure is generated in the air between the herringbone groove 31 formed on the outer peripheral portion of the rotary shaft 28 of the rotor 26 and the bearing cylinder 23, and the rotary shaft 28 moves relative to the bearing cylinder 23. It is rotated in a non-contact state.

Further, the herringbone groove 3 which is a dynamic pressure generating groove is formed on both surfaces of the rotary yoke 30 which rotates together with the rotor 26.
3 is provided, and the herringbone grooves 33 provided on both surfaces of the rotating yoke 30 when the rotor 26 rotates,
Both stationary surfaces 34 and 35 of the motor base 21 and the stator base 22
A dynamic pressure is generated in the air between and, and the rotating yoke 30 is rotated in a non-contact state with both stationary surfaces 34 and 35. In addition, when the motor is driven, the rotating yoke 30 and the permanent magnet 29 sandwich the armature coil 24 between them and integrally rotate to form a magnetic path.

Therefore, according to this embodiment, the following effects can be obtained. That is, the rotor 26 is supported by the radial bearing 32 at the center and is supported by the thrust bearing 3 at the bottom.
Since it is supported by 6a and 36b, it is more stable as compared with the case where it is supported only by the central portion. Further, these bearings 32, 36a and 36b are composed of dynamic pressure gas bearings, and the rotary shaft 28 Since the rotor rotates with the bearing cylinder 23, the rotating yoke 30, and the stationary surfaces 34 and 35 in a non-contact state, the generation of vibration can be prevented as much as possible. Therefore, the track width of the magnetic disk can be narrowed to increase the storage capacity.

Further, the thrust bearings 36a and 36b can sufficiently regulate the axial movement of the rotor 26 which occurs because the radial bearing 32 is a dynamic pressure bearing. Therefore, there is no risk of the magnetic disk colliding with the magnetic head. Further, since the permanent magnet 29 and the rotary yoke 30 forming a magnetic path rotate integrally with the permanent magnet 29 with the armature coil 24 sandwiched between them, the change of the magnetic flux does not occur, so that the generation of the eddy current can be suppressed, A highly efficient motor with low power consumption even at high speed rotation. Further, a magnetic attractive force acts between the permanent magnet 29 and the rotary yoke 30, but the magnetic attractive force acting on both is received by the rotary shaft 28 and offset, so that the permanent magnet 29 and the rotary yoke 30. The magnetic attraction force acting between the two is not applied to the thrust bearings 36a and 36b. Therefore, the thrust load acting on the thrust bearings 36a and 36b can be made equivalent to the weight of the rotor 26.

FIG. 3 shows a second embodiment of the present invention. Unlike the first embodiment, the stator base 2 is used in this embodiment.
2 between the bearing sleeve 23 and the rotary shaft 28 that are integrally formed with the rotary yoke 30, the rotary yoke 30, the motor base 21, and the stator base 22.
Bearing oil (not shown) is injected between the two to form a hydrodynamic bearing. A seal mechanism 37 is provided between the upper end of the bearing sleeve 23 and the inner surface of the rotor yoke 27 axially opposed to the upper end of the bearing sleeve 23 in order to prevent the bearing oil from splashing outside when the motor is driven. There is. The seal mechanism 37 has an annular shape that surrounds the rotary shaft 28 and is fixed to the inner surface of the rotor yoke 27 by adhesive bonding, and the bearing cylinder 2 facing the magnet ring 38.
It is composed of a magnetic body ring 39 having a substantially U-shaped cross section attached and fixed to the upper end of 3, and a magnetic fluid 40 interposed between the magnet ring 38 and the magnetic body ring 39. Also in this case, the rotor 26 is rotatably supported via the radial bearing 32 at the center and the thrust bearings 36a and 36b at the bottom. Also in such a second embodiment, the same operational effect as in the first embodiment can be obtained.

FIG. 4 shows a third embodiment of the present invention.
The following points are different from the first embodiment described above. That is, the stator 41 includes a plurality of armature coils 24 that are previously integrated with the upper surface of the stator base 42 by resin molding.
Is formed, and the inner peripheral portion of the mold resin 43 of the mold coil is formed as an armature coil molded body as a bearing cylinder 44 as a bearing. In addition,
The molded coil is obtained by arranging a plurality of coils formed by winding a copper foil in an annular shape, molding this with a resin to form a cylindrical shape, and slicing the cylindrical object to a predetermined thickness. It is a thing.

Even in such a structure, the above-mentioned first
It is possible to obtain the same effects as the embodiment, and in addition, in the first and second embodiments described above, the stator 25 has a plurality of armature coils 24 annularly equidistantly arranged on the upper surface of the stator base 22. It was arranged and glued with an adhesive,
In the case where a plurality of armature coils 24 are integrally formed in advance as in the present embodiment, the arrangement of the armature coils 24 has already been made, so workability is good, and the resin of the mold coil 43 is The number of parts can be reduced by using the bearing cylinder 44 at the peripheral portion.

FIG. 5 shows a fourth embodiment of the present invention, and the points different from the third embodiment will be described below. A substantially circular recess 46 as a bearing is provided in the center of the motor base 45, and the rotary shaft 47 is configured so as to penetrate the rotary yoke 30 and the lower end portion thereof to enter the recess 46. The herringbone groove 3 is formed on the outer peripheral surface of the rotating shaft 47 facing the bearing tube 32 and the outer peripheral surface facing the recess 46.
1, 48 are provided and are radial bearings 3 which are dynamic pressure bearings.
2, 49 are configured. Therefore, in this case, the rotary shaft 47 has two radial bearings 3 sandwiching the rotary yoke 30.
Since the rotors 2 and 49 are supported, the rotor 26 is more stably supported when the motor is driven.

In this case, in the stator 41, instead of the one in which the inner peripheral portion of the mold resin 43 of the molded coil shown in FIG. 5 is used as the bearing cylinder 44, the bearing cylinder 23 is erected at the center of the stator base 22 described above. It may be provided.

In each of the above embodiments, the rotary shaft 2
Herringbone grooves 31, provided on the outer peripheral surface of 8, 47,
48 may be provided on the inner peripheral surfaces of the bearing cylinders 23 and 44 facing each other and the inner peripheral surface of the concave portion 46 of the motor base 45. Further, the herringbone grooves 33 provided on both surfaces of the rotary yoke 30 are provided on the rotary yoke 30. Stator stand 22, 42 facing both sides
The stationary surface 35 and the stationary surfaces 34 of the motor bases 21 and 45 may be provided. Further, the application of the motor is not limited to the spindle motor of the hard disk drive device.

[0024]

According to the axial gap type motor of the first aspect of the invention, a dynamic bearing is provided in either the rotary shaft or the bearing sleeve surrounding the rotary shaft to form a radial bearing composed of the dynamic bearing. Therefore, the rotation shaft and the bearing sleeve do not come into contact with each other when the rotor rotates, so that the generation of vibration can be suppressed.

Further, since the dynamic pressure generating groove is provided on both surfaces of the rotating body or on the stationary surface facing both sides of the rotating body to form the thrust bearing composed of the dynamic pressure bearing, the axial movement of the rotor is restricted. You can

According to the axial gap type motor of the second aspect, since the rotating body is made of a magnetic body, it also functions as a stator yoke to form a magnetic path, and the rotating body is provided between the rotating body and the permanent magnet. Since the permanent magnet and the rotating body rotate integrally as a result of being provided on the rotating shaft of the rotor with the armature coil sandwiched between them, eddy current generated in the rotating body can be suppressed, so high efficiency with low power consumption even at high speed rotation. It becomes the motor of. Further, since the magnetic attraction force acting between the permanent magnet and the rotating body can be canceled out in the rotor, the thrust load can be made equivalent to the weight on the rotor side.

According to the axial gap motor of the third aspect, since the plurality of armature coils are integrally formed of resin, the workability in disposing the armature coils on the stator is good, Further, since the bearing tube is integrated with the stator, the number of parts can be reduced and the assembling becomes easy.

According to the axial gap type motor of the fourth aspect, the dynamic bearing in the radial direction is formed at two places, so that the rotor can be supported more stably.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a first embodiment of the present invention.

FIG. 2 is a plan view of a rotary yoke.

FIG. 3 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 4 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 1 showing a fourth embodiment of the present invention.

FIG. 6 is a diagram corresponding to FIG. 1 showing a conventional configuration.

[Explanation of symbols]

24 is an armature coil, 25 and 41 are stators, 26 is a rotor, 28 and 47 are rotating shafts, 29 is a permanent magnet for field magnetism, 3
Reference numeral 0 is a rotary yoke (rotating body), 32 and 49 are radial bearings, 34 and 35 are stationary surfaces, and 36a and 36b are thrust bearings.

Claims (4)

[Claims] 1. A rotor having a permanent magnet for field magnet axially opposed to the armature coil rotatably provided on a stator having a plurality of armature coils arranged in a plane. A rotating body provided on the rotating shaft of the rotor so as to sandwich the armature coil with a magnet, and a dynamic pressure generating groove is formed on both surfaces of the rotating body or a stationary surface facing both surfaces of the rotating body. A dynamic bearing is provided to form a thrust bearing, and a dynamic pressure generating groove is provided on either the rotary shaft or the inner surface of the bearing cylinder that surrounds the rotary shaft to form a radial bearing. Axial gap type motor. 2. The axial gap type motor according to claim 1, wherein the rotating body is made of a magnetic body. 3. The stator has an armature coil molded body in which a plurality of armature coils are integrally formed of resin, and a bearing is integrally formed on the inner diameter side of the resin portion. The axial gap type motor according to item 1 or 2. 4. A radial bearing, wherein the rotary shaft is extended to the side opposite to the armature coil of the rotary body, and a dynamic pressure generating groove is provided on either the rotary shaft or the inner surface of the bearing cylinder portion, the radial bearing is provided on both sides of the rotary body. It is comprised by the place, The claim 1 characterized by the above-mentioned.
4. The axial gap type motor according to any one of 1 to 3.