JP2000083345A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attenuate transferred vibration with stability and thereby reduce noise and produced gas by forming on the inside diameter side of a cylindrical portion projections, the inside diameter of which is smaller than the inside diameter of the cylinder. SOLUTION: A fixed shaft 3 is provided with grooves 26a and 26b. Wires 15 are wound on the stator core 16 of a stator 2 via an insulating member 20 of synthetic resin in-between. A cylindrical portion 22 constituting the insulating member 20 has a plurality of projections 23 extending in the axial direction. The fixed shaft 3 and the stator 2 are precisely fixed, together with the grooves 26a and 26b in the fixed shaft 3 engaged with the projections 23 on the stator 2. Since the stator core 16 is thus fixed indirectly on the fixed shaft 3 with the cylindrical portion 22 in-between, vibration produced by currents passed through a winding 15 of the stator 2 is not transferred directly to the fixed shaft 3 and vibration which is transferred from the fixed shaft 3 to a bracket 5, base 6, cover 7 and the like is attenuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a high-speed rotation type brushless motor used for a magnetic disk drive in the OA field which is required to be small and thin, and more particularly to a brushless motor rotating at 10,000 rpm or more. And a structure for preventing vibration and noise.

[0002]

2. Description of the Related Art A brushless motor for rotating a magnetic disk such as a magnetic disk device in the OA field is required to rotate at a higher speed in order to increase a data transfer speed and realize a quick access time.

[0003] Therefore, in order to satisfy this demand, the brushless motor has been increasing its rotation speed. In recent years, the number of revolutions of a brushless motor has been increased to 7,200 per minute.
Reached 10,000 revolutions per minute from rotation, 1500 in the future in the future
Zero rotation is required. However, as the rotational speed of the brushless motor increases, the current flowing through the winding of the stator increases. As a result, vibration occurs in the windings of the brushless motor and the stator core itself. This vibration of the stator and windings is transmitted to the fixed shaft that holds the stator, causing the brackets, bases, and covers fixed to the fixed shaft to vibrate, causing noise when the brushless motor rotates at high speed. Has become.

In order to solve such a problem, as shown in FIG.
The one disclosed in Japanese Patent No. 626 is known. A pair of rubber O-rings 4 for damping vibration are arranged at a predetermined interval between the stator 2 of the brushless motor and the fixed shaft 3 supporting the stator 2, and the stator 2 and the fixed shaft 3 There is known a structure for elastically retaining the pressure.

In the brushless motor having such a structure, the vibration excited by applying a large current to the stator 2 is not directly transmitted to the fixed shaft 3 as in the past, but is transmitted through the O-ring 4. And is transmitted only in the attenuated state. As a result, the vibration transmitted from the fixed shaft 3 to the bracket 5, the base 6, and the cover 7 is attenuated, so that the above-described problem relating to the vibration can be significantly improved.

Further, as shown in FIG.
One disclosed in Japanese Patent No. 5216 is known. A structure in which an elastic adhesive 8 is filled between a stator 2 of a brushless motor and a fixed shaft 3 supporting the stator 2 is known. In the brushless motor having such a structure, the vibration excited by applying a large current to the stator 2 is not directly transmitted to the fixed shaft 3 by the elastic adhesive 8 but is attenuated through the elastic adhesive 8. It will be transmitted only in the state where it was done. As a result, the vibration transmitted from the fixed shaft 3 to the bracket 5, the base 6, and the cover 7 is attenuated, so that the above-mentioned problem relating to the vibration can be significantly improved.

[0007]

However, in the above-mentioned conventional structure, since the material constituting the O-ring is made of rubber, the degree of elasticity changes with the use environment temperature. Therefore,
At a low temperature, the elasticity becomes high and the vibration cannot be sufficiently absorbed. Further, at high temperatures, the elasticity is low, the vibration absorbing power is inferior, and the generated noise cannot be sufficiently absorbed at the use environment temperature, and the problem that the noise changes depending on the temperature remains. 2: In the configuration of the pair of O-rings, the axial height of the stator with respect to the magnet varies, and the axial variation due to the difference between the centers of the magnet and the stator (displacement of the magnetic center) occurs due to the variation in the height. There were also problems that occurred. In addition, an attractive force is generated between the stator itself and the facing magnet. Since the O-ring has low rigidity, an electromagnetic force generated when a large current flows is also added, and the O-ring has a problem that the stator itself vibrates in the radial direction during rotation. 3: The use of the elastic adhesive also had a problem that the gas generated from the adhesive adhered to the magnetic disk and caused destruction of data written on the magnetic disk and read errors. 4: In particular, when the rotation speed of the brushless motor is higher than 10,000 rotations, the frequency of vibration increases, and unpleasant noise is generated. Therefore, it is necessary to further improve the attenuation of the vibration transmission to the fixed shaft. There were issues that had to be met.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a motor which can stably attenuate the transmission of vibration in a motor operating temperature environment and which has low noise. An object of the present invention is to provide a brushless motor that generates less gas.

[0009]

SUMMARY OF THE INVENTION To solve the above problems, the present invention provides a fixed shaft fixed to a bracket, a hub rotatably supported on the fixed shaft via a pair of bearings, and a hub. A fixed magnet, a stator fixed to a fixed shaft so as to face the magnet, the stator has a winding and a stator core, and the stator core includes an insulating member made of a synthetic resin that covers the entire circumference. A flat portion to insulate the winding and the stator core, a cylindrical portion located between the fixed shaft and the stator core, and a protrusion having a protrusion inner diameter smaller than the cylindrical inner diameter of the cylindrical portion on the inner diameter side of the cylindrical portion. It is composed. As a result, the axial height of the stator core can be accurately positioned, and the vibration generated when current flows through the windings of the stator can be attenuated.

A fixed shaft fixed to the bracket, a hub rotatably supported on the fixed shaft via a pair of bearings, a magnet fixed to the hub, and a fixed shaft opposed to the magnet. The fixed stator has a winding and a stator core, and a rubber spacer for vibration absorption is provided between the fixed shaft and the stator.
This makes it possible to attenuate the vibration generated when a current flows through the winding of the stator with a simple configuration.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to a first aspect of the present invention is directed to a fixed shaft fixed to a bracket, a hub rotatably supported on the fixed shaft via a pair of bearings, and the hub. A stator fixed to the fixed shaft so as to face the magnet, the stator having a winding and a stator core, the stator core including an insulating member covering the entire circumference, The member is a flat portion for insulating the winding and the stator core, a cylindrical portion located between the fixed shaft and the stator core,
A projection having a projection inner diameter smaller than the cylindrical inner diameter of the cylindrical portion is formed on the inner diameter side of the cylindrical portion. By engaging the projection with the groove of the fixed shaft, the position of the stator can be accurately determined. Can be decided. And since the cylindrical part located between a fixed shaft and a starter is comprised with a different material, it has the effect | action of a damper.

According to a second aspect of the present invention, the insulating member has a vibration absorbing characteristic made of a synthetic resin, and the leading member generated when a current is supplied to the winding of the stator is wound. This has the effect of attenuating the transmission of vibration between the wire and the stator core, and between the stator core and the fixed shaft.

According to a third aspect of the present invention, there is provided a fixed shaft fixed to a bracket, a hub rotatably supported on the fixed shaft via a pair of bearings, and a hub fixed to the hub. A magnet, a stator fixed to the fixed shaft so as to face the magnet, the stator having a winding, a stator core, and an annular member, wherein the annular member insulates the stator core from the winding. Part, and a cylindrical part located between the fixed shaft and the stator core, and a protrusion having a protrusion inner diameter smaller than the cylindrical inner diameter of the cylindrical part is formed on the inner diameter side of the cylindrical part, and the flat part is formed. The annular member having a portion and the cylindrical portion having the protrusion is formed on both end surfaces of the stator core, and the protrusion is engaged with a groove of the fixed shaft to thereby position the stator. It can be determined accurately. And since the cylindrical part located between a fixed shaft and a starter is comprised with a different material, it has the effect | action of a damper.

According to a fourth aspect of the present invention, the insulating member has a vibration absorbing characteristic made of a synthetic resin. And an effect of attenuating transmission of vibration between the stator core and the stator core and the fixed shaft.

According to a fifth aspect of the present invention, the projection has a circumferential slit, and when the stator is pressed into the fixed shaft, the projection elastically deforms due to the slit. And the function of more reliably press-fitting the fixed shaft.

According to a sixth aspect of the present invention, a fixed shaft fixed to a bracket, a hub rotatably supported on the fixed shaft via a pair of bearings, and a hub fixed to the hub. A magnet, a stator fixed to the fixed shaft so as to face the magnet, the stator has a winding and a stator core, and a vibration-absorbing rubber spacer is provided between the fixed shaft and the stator. The vibration-absorbing rubber spacer positioned between the fixed shaft and the starter has an effect of reliably attenuating the vibration generated when current is supplied to the stator windings with a simple configuration.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the overall structure of a brushless motor according to a first embodiment of the present invention.
In FIG. 1, reference numeral 3 denotes a fixed shaft, and the fixed shaft 3 has a groove 26.
a and 26b. Reference numeral 2 denotes a stator, and a winding 15 is wound around the stator core 16 via an insulating member 20 made of a synthetic resin material.
The cylindrical portion 22 constituting the insulating member 20 is configured such that a plurality of protrusions 23 extend in the axial direction. The fixed shaft 3 and the stator 2 are fixed to each other by the groove 26 of the fixed shaft 3.
The protrusions 23 of the stator 2 are accurately fixed by being engaged with the protrusions a and 26b, respectively.

Reference numeral 1 denotes a hub into which a magnetic disk (not shown) can be inserted and attached to the outer periphery. An annular magnet 9 is fixed to the inner periphery of the hub 1. Hub 1
The upper bearing 10a is attached to the upper end of the upper bearing.

A lower bearing 10b is attached to the bush 11 fixed to the inner diameter of the lower end of the hub 1 in advance. Then, the inner ring of the lower bearing 10 b attached to the bush 11 is attached to the fixed shaft 3. And
An upper bearing 10a is inserted into the upper part of the fixed shaft 3. Also,
The bush 11 having the lower bearing 10b is inserted or press-fitted into the inner diameter of the lower end of the hub 1.

The upper bearing 10a and the lower bearing 10b are fixed to the fixed shaft 3, the upper bearing 10a is fixed to the hub 1, the lower bearing 1
It is desirable to use an adhesive to fix the bush 11 to the bush 11b. An upper bearing 10a and a lower bearing 10b are provided in the axial direction so as to sandwich the stator 2.

The upper magnetic fluid seal 12a and the lower magnetic fluid seal 12b are provided outside the upper bearing 10a and the lower bearing 10b via seal holding means 13a and 13b. Upper magnetic fluid seal 12a, lower magnetic fluid seal 1
Reference numeral 2b seals a region including the upper bearing 10a and the lower bearing 10b, and is for preventing bearing grease from scattering.

With the above-described assembly, the hub 1 having the magnetic disk (not shown) can be rotated around the fixed shaft 3 via the upper bearing 10a and the lower bearing 10b.

Reference numeral 5 denotes a bracket, which is firmly fixed in a hole located at the center of the fixed shaft 3. Bracket 5
A sealing seal 14 is attached to the top surface to seal the screw holes, and the printed circuit board 1 is
7 is attached.

Reference numeral 18 denotes a lead wire of the winding 15 wound around the stator 2, and is led out from the stator 2 to the bottom surface side of the bracket 5 through a lead hole 19 provided on the fixed shaft 3. Then, the drawn out leads 18 are soldered to the solder lands on the printed circuit board 17.

In the brushless motor completed as described above, the bracket 5 is fixed to the hole of the base 6. After a magnetic disk (not shown) is attached and fixed to the outer diameter portion of the hub 1, a cover 7 is attached to a screw portion on the top surface of the fixed shaft 3 via a screw (not shown). It is completed as a magnetic disk drive.

FIG. 2 is a sectional view of the stator according to the first embodiment of the present invention. In FIG. 2, 2 is a stator,
A winding 15, a stator core 16, and an insulating member 20 made of a synthetic resin that covers the entire circumference of the stator core 16 are provided.

The insulating member 20 includes the winding 15 and the stator core 1.
6 is composed of a flat portion 21 for insulation, and a cylindrical portion 22 located between the fixed shaft 3 and the stator core 16. The cylindrical inner diameter D1 of the cylindrical part 22 is provided on the inner diameter side of the cylindrical part 22.
A plurality of protrusions 2 having a smaller protrusion inner diameter D2
3 are configured. Flat part 21, cylindrical part 22, projection part 2
3 is formed integrally with the stator core 16.

The projections 23 are formed by grooves 26a, 26b of the fixed shaft 3.
The projection 23 and the grooves 26a, 2
6b, the stator 2 can be accurately positioned on the fixed shaft 3. And the projection 23
Since a plurality of slits 27 are formed in the circumferential direction, even when the stator 2 is pressed into the fixed shaft 3,
When the protrusion 23 is elastically deformed by the slit 27, the protrusion inner diameter D2 of the protrusion 23 expands, and the stator 2
Press-fitting between the shaft and the fixed shaft 3 can be performed more smoothly.

The stator core 16 on which the winding 15 is wound in this manner is indirectly fixed to the fixed shaft 3 via the cylindrical portion 22, so that the vibration generated by the current flowing through the winding 15 of the stator 2 Is not directly transmitted to the fixed shaft 3.

As a result, the vibration transmitted from the fixed shaft 3 to the bracket 5, the base 6, the cover 7 and the like is attenuated, so that the problem relating to the vibration can be greatly improved.

(Embodiment 2) FIG. 3 is a sectional view of a stator according to Embodiment 2 of the present invention. In FIG. 3, reference numeral 2 denotes a stator, which includes a winding 15, a stator core 16, and an annular member 24 made of a synthetic resin material. Annular member 24
Is a flat portion 2 for insulating the winding 15 from the stator core 16.
1 and a cylindrical portion 22 located between the fixed shaft 3 and the stator core 16. On the inner diameter side of the cylindrical portion 22, a projection inner diameter D smaller than the cylindrical inner diameter D1 of the cylindrical portion 22 is provided.
A plurality of protrusions 23 each having 2 are formed.
Further, since the projection 23 is formed with a plurality of slits 27 in the circumferential direction, even when the stator 2 is pressed into the fixed shaft 3, the projection 23 is elastically deformed by the slit 27 so that the projection 23 is deformed. , The press fit between the stator 2 and the fixed shaft 3 can be made smoother.

A cylindrical portion 2 having a flat portion 21 and a projection 23
2 are formed on both end faces of the stator core 16, and the stator 2 is completed by applying the winding 15. In this way, the stator core 16 around which the winding 15 is wound is indirectly fixed to the fixed shaft 3 via the cylindrical portion 22, so that the vibration generated by the current flowing through the winding 15 of the stator 2 directly It is not transmitted.

As a result, the vibration transmitted from the fixed shaft 3 to the bracket 5, the base 6, and the cover 7 is attenuated.
Vibration problems can be greatly improved.

Since the annular member 24 is not integrally formed with the stator core 16, the annular member 24 can be used even if the thickness of the stator core is changed, and can be freely adapted to the thickness of the stator core 16.

(Embodiment 3) FIG. 4 is a sectional view showing the overall structure of a brushless motor according to Embodiment 3 of the present invention.
In FIG. 4, reference numeral 1 denotes a hub into which a magnetic disk (not shown) can be inserted and attached to the outer periphery. Then, a magnet 9 is fixed to the inner periphery of the hub 1. An upper bearing 10a is attached to the upper end of the hub 1. The stator 2 is fixed to a position substantially opposite to the magnet 9 at a substantially central portion of the fixed shaft 3. Spacer 2 made of rubber for absorbing vibration between fixed shaft 3 and stator 2
5 are provided. The spacer 25 is preferably made of a material such as synthetic rubber. A lower bearing 10b is attached to a bush 11 fixed to the inner diameter of the lower end of the hub 1 in advance. Then, the inner ring of the lower bearing 10 b attached to the bush 11 is attached to the fixed shaft 3.

The fixed shaft 3 is inserted or press-fitted into the upper bearing 10a, and the bush 11 is inserted or press-fitted into the inner diameter of the lower end of the hub 1.

Fixing of the upper bearing 10a, lower bearing 10b and the fixed shaft 3, fixing of the upper bearing 10a and the hub 1, lower bearing 10b
It is desirable that an adhesive be used in combination with the bush 11 for fixing. A winding 15 is wound around the stator core 16 on the stator 2. An upper bearing 10a and a lower bearing 10b are provided in the axial direction so as to sandwich the stator 2.

The upper magnetic fluid seal 12a and the lower magnetic fluid seal 12b are provided outside the upper bearing 10a and the lower bearing 10b via seal holding means 13a and 13b. Upper magnetic fluid seal 12a, lower magnetic fluid seal 1
Reference numeral 2b seals a region including the upper bearing 10a and the lower bearing 10b, and is for preventing bearing grease from scattering.

With the above assembly, the hub 1 having the magnetic disk (not shown) can be rotated around the fixed shaft 3 via the upper bearing 10a and the lower bearing 10b.

Reference numeral 5 denotes a bracket which is fixed to a hole located at the center of the fixed shaft 3. A sealing seal 14 is attached to the top surface of the bracket 5 to seal the screw holes, and a printed circuit board 17 is attached to the bottom surface of the bottom surface of the bracket 5.

Reference numeral 18 denotes a lead wire of the winding 15 wound around the stator 2, and is led out from the stator 2 to the bottom surface side of the bracket 5 through a lead hole 19 provided on the fixed shaft 3. Then, the drawn out leads 18 are soldered to the solder lands on the printed circuit board 17.

In the brushless motor completed as described above, the bracket 5 is fixed to the hole of the base 6. After a magnetic disk (not shown) is attached and fixed to the outer diameter portion of the hub 1, a cover 7 is attached to a screw portion on the top surface of the fixed shaft 3 via a screw (not shown). It is completed as a magnetic disk drive.

Since the stator core 16 around which the winding 15 is wound is indirectly fixed to the fixed shaft 3 via the spacer 25, the vibration generated by the current flowing through the winding 15 of the stator 2 directly affects the fixed shaft 3. Is not transmitted to

As a result, the vibration transmitted from the fixed shaft 3 to the bracket 5, the base 6, the cover 7 and the like is attenuated, so that the problem relating to the vibration can be greatly improved.
In particular, since the spacer 25 covers the entire thickness of the stator core 16 in the axial direction, the spacer 25 is one minute per minute of the brushless motor.
The effect of noise and reduction in high-speed rotation of 10,000 rotations or more is great.

[0046]

As is clear from the description of the above embodiment,
According to the first aspect of the invention, the position of the stator can be accurately determined in the axial direction by engaging the protrusion of the cylindrical portion of the stator with the groove of the fixed shaft. Therefore, since the axial height of the stator with respect to the magnet can be reliably determined, no magnetic attraction force is generated due to the difference between the centers of the magnet and the stator (displacement of the magnetic center). Can be prevented.

Since the insulating member covers the entire surface of the stator core, it has the effect of improving the rust prevention effect of the stator core. By using a resin material having vibration absorbing characteristics for the insulating member, it is possible to attenuate the transmission of vibration generated from the windings and the stator itself even when the rotation speed of the brushless motor increases. . Accordingly, a low-noise, low-vibration brushless motor can be provided.

According to the third aspect of the present invention, it is possible to provide a low-noise, low-vibration motor by attenuating the transmission of vibration to the windings and the stator itself. And, it can be used even if the thickness of the stator core is changed, and can be freely adapted to the thickness of the stator core.

According to the sixth aspect of the present invention, it is possible to reduce the amount of gas generated from the motor and to attenuate the vibration generated when a current is supplied to the winding of the stator with a simple configuration.

In particular, with these configurations, a great effect can be expected in reducing vibration and noise when the brushless motor rotates at high speed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall structure of a brushless motor according to a first embodiment of the present invention.

2A is a top view of the stator in FIG. 1; FIG. 2B is a cross-sectional view of the stator in FIG.

3A is a top view of a stator according to a second embodiment of the present invention. FIG. 3B is a cross-sectional view of the stator according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing the overall structure of a brushless motor according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing the entire structure of a conventional brushless motor.

FIG. 6 is a sectional view showing the entire structure of a conventional brushless motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hub 2 Stator 3 Fixed axis 4 O-ring 5 Bracket 6 Base 7 Cover 8 Elastic adhesive 9 Magnet 10a Upper bearing 10b Lower bearing 11 Bush 12a, 12b Magnetic fluid seal 13a, 13b Seal holding means 14 Sealing seal 15 Winding 16 Stator core DESCRIPTION OF SYMBOLS 17 Printed circuit board 18 Lead wire 19 Lead hole 20 Insulating member 21 Flat part 22 Cylindrical part 23 Protrusion part 24 Annular member 25 Spacer 26a, 26b Groove 27 Slit D1 Cylindrical inner diameter D2 Protrusion inner diameter

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Keisuke Ueda 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference)

Claims (6)

[Claims] A fixed shaft fixed to a bracket;
A hub rotatably supported on the fixed shaft via a pair of bearings, a magnet fixed to the hub, and a stator fixed to the fixed shaft so as to face the magnet; Has a winding and a stator core, the stator core includes an insulating member that covers the entire circumference,
The insulating member has a flat portion for insulating the winding and the stator core, a cylindrical portion located between the fixed shaft and the stator core, and a protrusion smaller than the cylindrical inner diameter of the cylindrical portion on the inner diameter side of the cylindrical portion. A brushless motor comprising a projection having an inner diameter. 2. The brushless motor according to claim 1, wherein the insulating member is made of a synthetic resin and has a vibration absorbing property. 3. A fixed shaft fixed to the bracket,
A hub rotatably supported on the fixed shaft via a pair of bearings, a magnet fixed to the hub, and a stator fixed to the fixed shaft so as to face the magnet; Has a winding, a stator core, and an annular member, the annular member includes a flat portion that insulates the stator core and the winding, a cylindrical portion positioned between the fixed shaft and the stator core, A protrusion having an inner diameter smaller than the inner diameter of the cylindrical portion on the inner diameter side of the portion, the annular member having the flat portion and the cylindrical portion having the protrusion, the annular member of the stator core Brushless motors arranged on both ends. 4. The brushless motor according to claim 3, wherein the insulating member is made of a synthetic resin and has a vibration absorbing property. 5. The brushless motor according to claim 1, wherein the protrusion has a plurality of slits in a circumferential direction. 6. A fixed shaft fixed to the bracket,
A hub rotatably supported on the fixed shaft via a pair of bearings, a magnet fixed to the hub, and a stator fixed to the fixed shaft so as to face the magnet; A brushless motor comprising: a winding and a stator core; and a vibration-absorbing rubber spacer provided between the fixed shaft and the stator.