JP2001211589A - Core insulation structure for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an operating environment for motor by preventing generation of an anion such as chlorine ion while securing a necessary film thickness of an insulation layer of an edge part of a core 14. SOLUTION: The insulation layer for the core 14 composed of an epoxy resin is made with a high viscosity without adding chlorine family additives or the like into it. An inorganic filler contained in the powder of the epoxy resin is made with a minimized grain with a diameter of 1 μm or less, increasing the bulk density of the filler or the spherical surface of the filler, and thereby reducing the melting flowability of the epoxy resin at a high temperature when the powder of epoxy resin is cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor core insulating structure provided with an insulating layer covering the surface of a core.

[0002]

2. Description of the Related Art Generally, an insulating layer for obtaining a required withstand voltage is formed on a surface of various cores used in a motor. For example, in a small-sized spindle motor (micromotor), the thickness of the insulating layer covering the flat portion of the core is set to 50 μm or more so as to ensure a withstand voltage of 500 V, and the edge of the core is In some cases, the edge coverage of the insulating layer to be covered is set to 60% or more. The above-mentioned edge coverage refers to the ratio of the thickness of the edge portion to the thickness of the insulating layer in the flat portion of the core.

As a means for forming such an insulating layer of the core, it has been conventionally known to apply an epoxy resin powder by spray gun coating. A filler, a chlorine-based additive, or a pigment is added. These inorganic fillers and additives act to reduce the melt fluidity of the epoxy resin powder at high temperatures, and by adding them, it is necessary for the edge portion of the core. The film thickness can be secured.

[0004]

However, when an insulating layer is formed by adding a chlorine-based additive as described above, anions (negative ions) such as chlorine ions are generated from the insulating layer. As a result, the use environment of the motor may be degraded. For example, in the case of a motor for a hard disk drive (HDD), anions such as chlorine ions generated from the insulating layer may cause so-called chemical contamination and damage media such as magnetic disks and recording heads. There is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor core insulating structure which has a simple structure and can prevent the generation of anions such as chloride ions while obtaining a required dielectric strength voltage. .

[0006]

According to a first aspect of the present invention, there is provided a motor core insulating structure in which a core constituting a stator or a rotor is covered with a film-like insulating layer. In the core insulating structure, the insulating layer is formed of a film obtained by melting and curing an epoxy resin powder containing an inorganic filler, and the average particle diameter of the inorganic filler is a high-temperature melt flow of the epoxy resin powder. The particle size is set to a small particle size of 1 μm or less so as to reduce the property.

Further, in the motor core insulating structure according to the second aspect, the average particle diameter of the inorganic filler according to the first aspect is set to 0.01 μm or more.

Further, in the motor core insulating structure according to the third aspect, the insulating layer according to the first or second aspect is set so that a general film thickness in a flat portion of the core is 50 μm or more. An edge coverage, which is a ratio of the above-described general thickness to the thickness of the insulating layer covering the edge of the core, is set to 60% or more.

Further, in the motor core insulating structure according to a fourth aspect, the insulating layer according to the third aspect is used for a winding core on which a winding is applied, and The withstand voltage is set to a required value or more.

In the motor core insulating structure according to any one of the first to fourth aspects of the present invention, the inorganic filler contained in the epoxy resin powder constituting the insulating layer has a small particle size of 1 μm or less. By having a diameter, the bulk density of the inorganic filler, that is, the surface area has been increased, thereby reducing the melt fluidity at a high temperature when the epoxy resin powder is cured,
The viscosity can be increased without adding a conventional chlorine-based additive. As a result, the required film thickness for the edge portion of the core can be obtained satisfactorily without generating anions such as chloride ions.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, as an example of a motor according to the present invention, an overall structure of a fixed-shaft HDD spindle motor shown in FIG. 1 will be described.

The entire HDD spindle motor shown in FIG. 1 is composed of a stay set 10 as a fixing member and a rotor set 20 as a rotating member assembled to the stator set 10 from above in the figure. It is configured. The stator set 10 includes a frame 11 as a bearing support frame screwed to a fixed base (not shown), and a hollow cylindrical core holder 12 is provided at a substantially central portion of the frame 11. Are provided so as to stand integrally.

A stator core 14 made of a laminate of silicon steel plates is fitted on the outer peripheral wall surface of the core holder 12. An insulating layer according to the present invention having a configuration described later is formed on the surface of the stator core 14 by coating, and is wound around portions corresponding to the salient pole portions of the stator core 14 via the insulating layer. The wire 15 is wound.

On the other hand, a fixed shaft 13 is fixed to a substantially central portion of the frame 11 so as to protrude upward. The fixed shaft 13 is made of, for example, stainless steel (S
US420J2), and the upper and lower ends of the fixed shaft 13 in the figure are formed using female screw tap holes 13a and 13b provided at the both ends.
It is adapted to be screwed to a fixed base (not shown).

A rotary hub 21 is rotatably mounted on the outer peripheral side of the fixed shaft 13 via a bearing sleeve 22 as a bearing member constituting the rotor set 20. That is, in the rotor set 20, a rotary hub 21 for supporting a predetermined recording medium (not shown) is fitted on the outer peripheral side of the bearing sleeve 22. The rotary hub 21 has a substantially cylindrical body 21a on which a magnetic recording medium such as a magnetic disk is mounted on the outer periphery, and a back yoke 21b is provided on the inner peripheral wall side of the body 21a. The drive magnet 21c is annularly mounted. The driving magnet 21c is connected to the stator core 14 described above.
Are arranged in such a manner as to annularly face the outer peripheral end surfaces of the salient pole portions.

A pair of bearing projections 23 are formed on the inner peripheral wall of the center hole of the bearing sleeve 22 at predetermined intervals in the axial direction.
23 are opposed to each other so as to approach the outer peripheral surface of the fixed shaft 13. And each of these bearing projections 2
Dynamic pressure surfaces provided on the inner peripheral surfaces of the fixed shaft 1 and the fixed shaft 1;
A pair of adjacent radial dynamic pressure bearing portions RBa and RBb are provided so as to be arranged in parallel in the axial direction by a dynamic pressure surface formed on the outer peripheral surface of the third bearing 3. The hub 21 is formed by the pair of radial dynamic pressure bearing portions RBa and RBb.
Are supported so as to be rotatable in the radial direction with respect to the fixed shaft 13.

That is, each of the radial dynamic pressure bearing portions RB
In a and RBb, the dynamic pressure surface on the bearing sleeve 22 side and the dynamic pressure surface on the fixed shaft 13 side are arranged circumferentially facing each other with a small gap of several μm therebetween. Are formed so as to be continuous. In each of these bearing spaces, lubricating oil (oil) is independently injected, and an enlarged space in which a portion between both dynamic pressure bearing portions RBa and RBb is depressed outward in the radial direction. B has an air layer in communication with the atmosphere.

A pair of radial dynamic pressure generating grooves each having a herringbone shape (not shown) are annularly arranged on at least the dynamic pressure surfaces on the bearing sleeve 22 side of the pair of dynamic pressure surfaces. When the rotary hub 21 rotates, the lubricating oil is pressurized and pressurized by the pumping action of the two radial dynamic pressure generating grooves, and a dynamic pressure is generated. The pressure is such that the rotary hub 21 is axially supported in the radial direction.

Further, each of the radial dynamic pressure bearing portions RB
Capillary seal portions as lubricating oil holding portions are provided at both ends in the axial direction of the bearing space constituting the a and RBb so as to sandwich the radial dynamic pressure bearing portions RBa and RBb from both sides in the axial direction. Each of these capillary seal portions gradually expands a gap between the bearing sleeve 22 and the fixed shaft 13 outwardly of the bearing by an inclined surface formed on the bearing sleeve 22 side, The liquid level of the lubricating oil is set so as to be a predetermined position inside each capillary seal portion regardless of whether the motor rotates or stops.

Further, a disc-shaped thrust plate 16 is fixed to a tip end portion (upper end portion in the drawing) of the fixed shaft 13. The thrust plate 16 is disposed so as to be accommodated in a cylindrical recess formed in the above-described center portion of the bearing sleeve 22 in the upper part of the drawing, and is provided on the bottom wall of the recess of the bearing sleeve 22. The lower thrust dynamic pressure bearing portion SBa is configured by a dynamic pressure surface provided on the lower surface side of the thrust plate 16 shown in the figure being arranged close to the dynamic pressure surface in the axial direction.

A counter plate 24 made of a large disc-shaped member extends toward the center toward the upper outer peripheral side of the bearing sleeve 22 so as to approach the dynamic pressure surface on the upper surface side of the thrust plate 16 in the drawing. So that it is attached. The dynamic pressure surface provided on the lower surface side of the counter plate 24 in the figure and the thrust plate 1
The upper thrust dynamic pressure bearing portion SBb is constituted by the dynamic pressure surface provided on the upper surface side of FIG.

That is, in each of a pair of thrust dynamic pressure bearing portions SBa, SBb arranged adjacent to each other, the bearing sleeve 22 and the counter plate 2
The four dynamic pressure surfaces on the four sides and the two dynamic pressure surfaces at both axial end surfaces of the thrust plate 16 are arranged facing each other in the axial direction with a small gap of several μm therebetween. Lubricating oil (oil) is independently injected into each bearing space consisting of a set of narrow gaps spaced apart by a predetermined distance in the axial direction through the shaft.

In this embodiment, a thrust dynamic pressure generating groove having a herringbone shape (not shown) is formed in an annular shape with respect to each of the dynamic pressure surfaces provided on both axial end surfaces of the thrust plate 16. When the rotary hub 21 is rotated, the lubricating oil is pressurized and pressurized by the pumping action of the two thrust dynamic pressure generating grooves to generate a dynamic pressure. The rotating hub 21 is configured to be axially supported in the thrust direction by the generated dynamic pressure.

Further, at both ends in the radial direction of the bearing space constituting the above-mentioned set of thrust dynamic pressure bearing portions SBa, SBb, a capillary seal portion is provided with each thrust dynamic pressure bearing portion SBa.
Ba and SBb are provided so as to sandwich them from both sides in the radial direction. Each of these capillary seal portions is formed by gradually increasing the gap between the thrust plate 16 and the bearing sleeve 22 toward the outside by an inclined surface formed on the thrust plate 16 side, and has a radius The capillary seal portion disposed on the inner side in the direction communicates with the above-described radial dynamic pressure bearing portion RBa side and the atmosphere on the motor outside side, and the liquid level position of the lubricating oil is either the rotation of the motor or the stop of the motor. Also in such a case, it is set so as to be at a predetermined position inside each capillary seal portion.

The counter plate 24 includes
A thin cover plate 26 is provided from the outside (the upper side in the figure) via an absorbent cloth 25. The absorbent cloth 25 and the cover plate 26 prevent the lubricant oil from scattering outside even in the worst case. Has become. Also, a thin cover plate 26 is provided on the outer side of the radial dynamic pressure bearing portion RBb on the lower side in the figure via a similar absorbent cloth 25, and the absorbent cloth 25 and the cover plate 26 In the worst case, the lubricating fluid is prevented from scattering outside.

Further, each of the dynamic pressure bearing portions RBa, R
Bb, SBa, and a necessary portion corresponding to the outer side of the device with respect to SBb are prevented from being wetted and diffused by lubricating oil adhering there or the lubricating oil of the bearing portion, and are repellent for facilitating wiping and cleaning work. Oil is applied.

On the other hand, as described above, the insulating layer (not shown) formed on the surface of the stator core 14 is formed.
Is composed of a film-like body formed of an epoxy resin powder containing an inorganic filler, and a predetermined amount of a curing agent and a pigment are mixed in the epoxy resin powder, No conventionally used additives such as chlorine are used. And as an alternative,
The average particle diameter of the inorganic filler is set to a value of 1 μm or less to reduce the particle diameter, thereby reducing the fluidity of the melt at a high temperature of the epoxy resin powder.

Here, the above-mentioned epoxy resin powder includes, for example, F219-TP (trade name, manufactured by Somar Co., Ltd.),
A wide variety of products such as Kayatron (trade name, manufactured by Nippon Kayaku) are used. As the inorganic filler, silica (SiO
2), alumina (Al2O3), magnesium oxide (MgO2) and the like are used, and as a curing agent, amine-based imidazole, acid anhydride and the like are used. Hereinafter, the composition of the insulating layer according to the present embodiment will be shown in comparison with a conventional configuration.

Conventional configuration (W%) This embodiment (W%) Epoxy resin powder 60 60 to 65 Inorganic filler 35 37.7 to 32.7 Hardener 22 Pigment 1.75 0.3 Additive 1. 750 (without addition)

The above pigment is used for coloring for confirming the presence or absence of the formation of the insulating layer, but is set to 1/6 or less (0.3 W% or less) of the conventional amount. ing.

Such an insulating layer is formed by, for example, a spray gun coating process. In this case, as shown in FIG. 2, first, the surface of the core material of the stator core 14 on which the insulating layer is formed is formed. Is appropriately roughened with a blast core, washed with an organic solvent, and then coated with an epoxy resin powder into a film by a coating process using a spray gun of a powder coating machine. The coated epoxy resin powder flows so as to be melted and spread over the entire core by the heat at the time of curing, and is formed into a thin film. And
Finally, a pure cleaning is performed.

At this time, in the insulating layer according to the present embodiment, the inorganic filler contained in the epoxy resin powder constituting the insulating layer is reduced to a particle size of 1 μm or less. The bulk density, ie the surface area, of the filler has been increased. Accordingly, since the fluidity of the melt at a high temperature when the epoxy resin powder is cured is reduced, the viscosity of the melt can be increased without adding a conventional chlorine-based additive. As a result, the coating is also performed well on the edge portion of the core, the required film thickness is obtained well, and the generation of anions such as chloride ions is well avoided.

More specifically, in the present embodiment, the general film thickness in the flat portion of the core 14 is set to be 50 μm or more, and the general film thickness (50
μm) and the thickness of the insulating layer covering the edge portion of the core 14 are set to be 60% or more. As a result, the withstand voltage of the insulating layer is set to a value required for the motor, for example, 500 V or more.

At this time, in actual use, the average particle size of the inorganic filler is set to 0.01 μm or more. This is because, when the particle size is further reduced, each particle will be adsorbed to each other and the fluidity will almost disappear, and from the same viewpoint, the average particle size of the inorganic filler is Is preferably set in the range of 0.1 μm to 0.2 μm.

As mentioned above, the embodiment of the invention made by the present inventor has been described differently. However, the present invention is not limited to the above-described embodiment, and can be moderately modified without departing from the gist thereof. Needless to say.

For example, in the above-described embodiment, the insulating layer is formed by spray coating, but the present invention can be similarly applied to an insulating layer formed by other means. In addition, the HDD as in the above-described embodiment
The present invention can be similarly applied to a motor other than the motor, for example, a polygon mirror driving motor or a CD-ROM driving motor.

[0037]

As described above, in the motor core insulating structure according to the present invention, the inorganic filler contained in the epoxy resin powder constituting the insulating layer covering the core is reduced to a particle size of 1 μm or less. Thereby, the bulk density of the inorganic filler, that is, the surface area is increased, thereby reducing the melt fluidity at a high temperature when the epoxy resin powder is cured, and adding a conventional chlorine-based additive. It is designed to increase the viscosity without causing any residual anions such as chloride ion, fluorine, bromine, nitrous acid, nitric acid, sulfuric acid and phosphoric acid while obtaining the required film thickness for the core edge. The generation can be prevented to be, for example, 0.05 μg / cm 2 or less, and the use environment of the motor can be favorably improved with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an example of the entire structure of a hard disk drive (HDD) as an example of a motor to which the present invention is applied.

FIG. 2 is a flowchart showing a process of forming an insulating layer according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 Stay overnight set 13 Fixed shaft 14 Stator core 15 Winding 20 Rotor set 22 Bearing sleeve 21 Rotating hub

Claims (4)

[Claims] In a motor core insulating structure in which a surface of a core constituting a stator or a rotor is covered with a film-like insulating layer, the insulating layer melts and cures an epoxy resin powder containing an inorganic filler. Wherein the average particle size of the inorganic filler is set to a small particle size of 1 μm or less so as to reduce the high-temperature melt flowability of the epoxy resin powder. Core insulation structure. 2. An inorganic filler having an average particle size of 0.0
2. The method according to claim 1, wherein the distance is set to 1 μm or more.
A motor core insulation structure as described. 3. The insulating layer according to claim 1, wherein the insulating layer has a general thickness of 50 μm or more in a flat portion of the core, and covers the general thickness and an edge portion of the core. An insulating core structure for a motor, wherein an edge coverage ratio, which is a ratio with respect to a film thickness of an insulating layer, is set to 60% or more. 4. The insulating layer according to claim 3, wherein the insulating layer is used for a winding core on which a winding is applied, and a withstand voltage of the insulating layer is set to a required value or more. Motor core insulation structure.