JP2015070669A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for having positional stability of a magnetic suction plate and suppressing the manufacturing cost while utilizing an adhesive in a structure in which the magnetic suction plate is fixed to a stator of a spindle motor.SOLUTION: In a base plate 2, an annual groove 14 is provided which holds an annual magnetic suction plate 13, the annual magnetic suction plate 13 is fixed to the groove 14 by adhesion, a plurality of projections 13a, 13b are provided on respective outer peripheral side and inner peripheral side of the magnetic suction plate 13, and the projections 13a, 13b are fitted to a wall surface of the groove 14 on the outer peripheral side and the inner peripheral side of the magnetic suction plate 13.

Description

  The present invention relates to a spindle motor characterized by a structure for fixing a magnetic suction plate.

  An outer rotor type spindle motor is known as a motor for driving a magnetic disk of a hard disk drive (HDD). In this spindle motor, an annular magnetic attraction plate is disposed on the portion of the base plate that faces the rotor magnet disposed on the hub in the axial direction in order to suppress fluctuations in the axial direction of the hub on which the magnetic disk is placed. By generating a magnetic attractive force between the magnetic attractive plate and the rotor magnet, the vertical movement of the hub in the axial direction can be suppressed.

  In the structure in which the magnetic attraction plate is fixed to the base plate, a structure in which a plurality of protrusions are provided on the inner peripheral side of the annular magnetic attraction plate is described in Patent Document 1, and conversely, a structure in which a plurality of protrusions are provided on the outer peripheral side It is described in.

Japanese Unexamined Patent Publication No. 2011-239587 JP 2007-43893 A

  As a method for fixing the magnetic attraction plate to the base plate, there are a press-fitting method and an adhesion method. The method using press fitting has a problem that the magnetic attraction plate is distorted by the pressure during press fitting. As described above, the magnetic attraction plate has a role of suppressing the vertical movement of the rotor in the axial direction, but this function is impaired if the magnetic attraction plate is distorted. In particular, a structure in which a protrusion is provided only on one of the inner peripheral side and the outer peripheral side as described in Patent Document 1 and Patent Document 2 and press-fitting using this protrusion is likely to cause distortion of the magnetic attraction plate.

  On the other hand, the bonding method has a problem that the position of the magnetic attracting body plate fluctuates due to expansion and contraction of the adhesive when the adhesive is cured. As a method for solving this problem, there is a method of holding the magnetic suction plate with a jig until the adhesive is cured, but the number of steps increases and the manufacturing cost increases.

  In such a background, the present invention is a structure in which the magnetic attraction plate is fixed to the stator of the spindle motor, and the position of the magnetic attraction plate is highly stable and the manufacturing cost can be suppressed while using an adhesive. The purpose is to provide.

  According to the first aspect of the present invention, there is provided a base plate, a shaft body that is rotatably supported on the base plate, a stator core around which a coil winding is wound and fixed to the base plate, and a shaft body that is fixed to the shaft body. A rotor member fixed to a portion of the rotor member facing the stator core in the radial direction, and attached to the base plate. The rotor magnet is disposed to face the rotor magnet in the axial direction, and is magnetic to the rotor magnet. An annular magnetic attraction plate for generating an attraction force, and the base plate is provided with an annular groove for holding the annular magnetic attraction plate, and the annular magnetic attraction plate is bonded to the annulus of the base plate by an adhesive. Each of the outer circumferential side and the inner circumferential side of the annular magnetic attraction plate A protruding portion is provided, and at least two protrusions of the plurality are fitted to the wall surface of the annular groove on the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate, respectively. It is a spindle motor.

  In the first aspect of the present invention, the inner peripheral side is the axial center side, and the outer peripheral side is the side away from the axial center. According to the first aspect of the present invention, since the projecting portions are provided on the outer side and the inner side of the annular magnetic attraction plate, the pressure received by the magnetic attraction plate fitted in the annular groove is offset, and the magnetic The deformation of the suction plate is suppressed. In addition, the magnetic attraction plate can be temporarily fixed to the groove by fitting the protruding portion to the wall surface of the groove, and the adhesive can be cured in this state. A structure is obtained in which the position of the magnetic attraction plate does not fluctuate when the agent is cured. Moreover, since the operation | work which fixes a magnetic attraction board with a jig | tool until an adhesive agent hardens | cures is not required, manufacturing cost does not rise. In addition, the state of fitting should just be a grade which a magnetic attraction plate is temporarily fixed to a groove | channel, and should just be a grade which a position shift of a magnetic attraction plate does not arise in the step which an adhesive agent hardens | cures.

  According to a second aspect of the present invention, in the first aspect of the invention, the plurality of protrusions on each of the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate are at equiangular positions in the circumferential direction. Three or more are provided, and are arranged at the same position on the outer peripheral side and the inner peripheral side in the circumferential direction. According to the second aspect of the present invention, the positions of the protrusions provided on the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate are the same in the circumferential direction, that is, the inner periphery is located inside the outer peripheral protrusion. Side projections are provided. For this reason, in the state fitted in the groove, the pressure directed from the outer peripheral side protruding portion toward the inner side (axial center direction) and the pressure directed from the inner peripheral side protruding portion toward the outer side (direction away from the axial center) are offset, The deformation of the annular magnetic attraction plate is suppressed.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the plurality of protrusions on each of the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate sag on the same side in the axial direction. The annular magnetic attraction plate is fitted into the annular groove from the side where the sag portion is present. According to the third aspect of the present invention, the fitting operation can be performed smoothly, and further, the material is prevented from being scraped at the fitting portion, and the generation of dust is prevented. Moreover, deformation of the member is also prevented.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, when viewed from the axial direction, the apex of the projecting portion on the outer peripheral side of the magnetic attraction plate is outside the rotor magnet. The apex of the protrusion on the inner peripheral side of the magnetic attraction plate is outside the inner diameter of the rotor magnet. According to the invention described in claim 4, there is no need to consider interference between the end face of the hub constituting the rotor and the end face of the magnetic attraction plate, and the gap between the end face of the rotor magnet and the end face of the magnetic attraction plate can be made narrower. Thus, the vertical movement of the hub in the axial direction can be suppressed by increasing the suction force.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the adhesive is filled in a gap between the wall surface of the annular groove and the annular magnetic attraction plate. It is characterized by that. According to the fifth aspect of the present invention, the adhesive reservoir is formed by filling the gap formed between the annular groove on the base plate side and the magnetic suction plate, and the annular magnetic field is formed on the base plate. The suction plate is fixed.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the annular magnetic attraction plate has a first diameter portion and a second diameter portion intersecting each other, The protrusion is provided on each of the outer peripheral side of the first diameter part and the inner peripheral side of the second diameter part, and the protrusion provided on the outer peripheral side of the first diameter part is the annular shape. The outer peripheral side of the groove is in contact with the inner peripheral side of the first diameter portion, and the inner peripheral side of the annular groove is not in contact with the outer peripheral side of the second radial portion. The protrusion provided on the inner peripheral side of the second diameter portion is not in contact with the outer peripheral wall of the groove, and is in contact with the inner peripheral wall of the annular groove.

  According to the sixth aspect of the present invention, the magnetic attraction plate is deformed in the direction of the first diameter portion and the direction of the second diameter portion inside the annular groove, and the groove is formed by the elastic force resulting from the deformation. The magnetic attraction plate is fitted. According to this structure, reliable fitting can be performed even if the tightening allowance is small.

  According to the present invention, in the structure in which the magnetic attraction plate is fixed to the stator of the spindle motor, a technique is provided in which the position of the magnetic attraction plate is highly stable and the manufacturing cost can be suppressed while using an adhesive. .

It is a sectional side view of an embodiment. It is a top view of an embodiment. It is the side view (A) and top view (B) of a magnetic attraction board. It is the enlarged view to which a part of FIG. 1 was expanded. It is a top view of other embodiments. It is the figure which expanded a part of FIG.

(Constitution)
FIG. 1 shows a spindle motor 1. FIG. 2 shows a top view of the state in which the rotating part (rotor) is removed from the spindle motor 1 as seen from the axial direction. The spindle motor 1 includes a base plate 2 serving as a base. The base plate 2 is made of aluminum, for example, and the stator core 3 is fixed. The stator core 3 has a structure in which a plurality of annularly processed electromagnetic steel plates are laminated in the axial direction. The stator core 3 has pole teeth (saliency poles) that extend in a direction away from the center of the shaft and are arranged along the circumferential direction. A coil winding 4 serving as a drive coil is wound around each pole tooth.

  A hole penetrating in the axial direction is provided at the center of the base plate 2, and a substantially cylindrical bearing portion 5 is fixed thereto. Minute gaps are provided between the inner periphery of the bearing portion 5 and the shaft 7 and between the end surface of the bearing portion 5 and the hub surface, and the gap is filled with a lubricant. Further, a dynamic pressure groove 6a for smoothly rotating the shaft 7 with respect to the bearing portion 5 is provided on the inner periphery of the bearing portion 5, and a movement for smoothly rotating the hub is provided on the upper end surface of the bearing portion 5. A pressure groove 6b is provided.

  A hole penetrating in the axial direction is provided at the center of the bearing portion 5, and a shaft 7 serving as a shaft member is fixed thereto. A flange portion 7 a is provided at the tip of the shaft 7 so that the shaft 7 does not fall out of the bearing portion 5. The bottom of the shaft 7 is covered with a bottom plate 8. A hub 9 that is a rotor member is fixed to the upper portion of the shaft 7. The hub 9 has a disk portion 10 and a cylindrical portion 11 extending in the axial direction from the outer edge thereof. Although not shown, a magnetic disk is fixed to the upper part of the disk part 10. An annular rotor magnet 12 is fixed on the inner side (axial center side) of the cylindrical portion 11. The rotor magnet 12 is a permanent magnet that is magnetized in a state where the polarity is alternately reversed with SNSN... Along the circumferential direction.

  The inner peripheral side of the rotor magnet 12 faces the outer periphery (outer peripheral surface of the pole teeth) of the stator core 3 with a gap therebetween. Further, one end surface (the lower surface in the drawing) of the rotor magnet 12 in the axial direction is opposed to the annular magnetic attraction plate 13 in the axial direction with a gap therebetween. FIG. 3 shows a side sectional view (A) and a top view (B) of an annular magnetic attraction plate. The annular magnetic attraction plate 13 is circular and is formed by punching a magnetic steel plate. The rotor magnet 12, the hub 9, the shaft 7, the bearing portion 5, and the bottom plate 8 constitute a rotor, and this rotor rotates with respect to the base plate 2.

  By passing a drive current through the coil winding 4 and switching the polarity, the magnetic attractive force and the magnetic repulsive force generated between the magnetic poles of the rotor magnet 12 and the pole teeth of the stator core 3 are switched, and the rotor magnet 12, hub 9, A rotor including the shaft 7, the bearing portion 5 and the bottom plate 8 rotates with respect to the base plate 2. At this time, the rotor magnet 12 is attracted to the magnetic attraction plate 13 in the axial direction, and the retaining portion (flange portion 7a) of the shaft 7 and the bearing due to the vertical movement of the hub 9 with respect to the base plate 2 in the axial direction and the change in the attitude of the hard disk drive. The contact of the part 5 is suppressed.

  An annular groove 14 is provided in the base plate 2. The groove 14 is circular, and an annular magnetic attraction plate 13 is fitted inside the groove 14 and is fixed by an adhesive. Here, four protrusions 13 a are provided on the inner peripheral side of the annular magnetic attraction plate 13, and four protrusions 13 b are provided on the outer peripheral side. Each of the four protruding portions 13a and 13b has the same position in the circumferential direction (angular position as viewed from the axial direction), and the protruding portions 13a and 13b are arranged back to back at the four positions. Yes. Further, each of the four protruding portions 13a and 13b is disposed at an equiangular angular position shifted by 90 ° when viewed from the axial direction. The protruding portions 13 a and 13 b are rounded at the protruding portions, and the tips of the rounded portions are in contact with the inner wall of the groove 14.

  Here, the dimension of each part is set so that the magnetic attraction plate 13 may be fitted into the groove 14 with an intermediate fit that does not move. That is, the inner diameter R1 (see FIG. 2) of the groove 14 is slightly larger than the inner diameter r1 (see FIG. 3) of the magnetic suction plate 13, and the outer diameter R2 of the groove 14 is slightly smaller than the outer diameter r2 of the magnetic suction plate 13. The magnetic attraction plate 13 is adjusted to be fitted in the groove 14 in a state of an intermediate fit. Specifically, the degree of fitting is adjusted to such an extent that it does not move relative to the vibration level and can be assembled and disassembled using a human hand.

  In the state where the magnetic attraction plate 13 is fitted in the groove 14, the protruding portion 13 a contacts the inner wall of the groove 14, the protruding portion 13 b contacts the outer wall of the groove 14, and the contact portion of the protruding portion 13 a A gap 15 is formed between the inner wall of the groove 13 and the inner peripheral surface of the magnetic attraction plate 13 at a portion other than the portion, and the outer wall of the groove 13 and the magnetic attraction plate 13 at a portion other than the contact portion of the protruding portion 13b. A gap 16 is formed between the outer peripheral surface and the outer peripheral surface.

  The gaps 15 and 16 are filled with an adhesive, and the magnetic attraction plate 13 is fixed inside the groove 14 by this adhesive. That is, the adhesive filled in the gaps 15 and 16 is hardened, so that the magnetic attraction plate 13 is fixed to the base plate 2 using the grooves 14.

  Specifically, the magnetic attraction plate 13 is formed by punching a magnetic steel plate, the inner diameter r is 17 mm, the outer diameter r2 is 19 mm, the thickness is 0.35 mm, and the protruding dimensions of the protruding portions 13a and 13b are 0.05 mm. In this case, the inner diameter R1 and the outer diameter R2 of the groove 13 are set so that the tightening margin is about 5 μm to 10 μm. That is, (R1-r1) / 2 and (R2-r2) / 2 are adjusted to be about 5 μm to 10 μm. In addition, as for the protrusion dimension of the protrusion parts 13a and 13b, 0.03-0.2 mm is suitable, and the interference margin has the preferable range of about 3 micrometers-12 micrometers.

  Further, sag portions 17 and 18 formed at the time of punching of the magnetic attraction plate 13 are provided at the edges of the protruding portions 13a and 13b on the base plate 2 side (see FIG. 4). The sag portions 17 and 18 are provided on the same side in the axial direction, and the magnetic attraction plate 13 is fitted into the groove 14 from the sag portion 17 and 18 side, so that the fitting operation is easily and smoothly performed. The deformation of the protrusions 13a and 13b can be suppressed. Further, the material is prevented from being scraped at the fitting portion, and the generation of dust is prevented.

  Further, the dimensions are set so that r1 is equal to or larger than the inner diameter of the rotor magnet 12 and r2 is equal to or smaller than the outer diameter of the rotor magnet 12. That is, the projecting dimensions of the projecting portions 13 a and 13 b are determined so that the magnetic attraction plate 13 is within the projection range of the rotor magnet 12 when viewed from the axial direction.

  Magnetic attraction force is also generated between the protrusions 13a and 13b and the rotor magnet 12, but the protrusions 13a and 13b are discontinuous in the circumferential direction, so there is also an influence of switching of magnetic poles, and during rotation The magnitude of this magnetic attractive force varies periodically. The influence of this periodically changing force is not large, but if the protruding dimension is larger than 0.03 to 0.2 mm, the influence cannot be ignored and causes vibration. Therefore, in the present embodiment, the influence of the magnetic attractive force acting on the protrusions 13a and 13b is suppressed by adopting the above-described dimensional relationship.

  The hub 10 is made of a magnetic material, and the cylindrical portion 11 also functions as a back yoke that suppresses leakage of magnetic flux from the rotor magnet 12. Here, in order to suppress the leakage magnetic flux from the end surface of the rotor magnet 12, the lower end portion in the axial direction of the cylindrical portion 11 protrudes in the axial direction from the lower end surface of the rotor magnet 12. In this example, by setting r2 to be equal to or smaller than the outer diameter of the rotor magnet 12, the lower end portion of the cylindrical portion 11 and the magnetic suction plate 13 when the gap between the rotor magnet 12 and the magnetic suction plate 13 in the axial direction is narrowed. Interference with the upper end surface of the is prevented. By narrowing the gap between the rotor magnet 12 and the magnetic suction plate 13, the hub 9 is effectively attracted to the base plate 2 side, the vertical movement of the hub 9 in the axial direction is suppressed, and the flange of the shaft 5 Contact between the portion 7a and the bearing portion 5 is prevented.

  The base 2 is provided with an annular convex portion 2 a for forming the groove 14, but by making r1 equal to or larger than the inner diameter of the rotor magnet 12, the convex portion 2 a becomes the stator core 3 and the coil winding 4. To avoid interference.

(Assembly process)
Hereinafter, an example of the operation of fixing the magnetic suction plate 13 to the groove 14 will be described. First, a thermosetting adhesive is injected into the groove 14 and then the magnetic attraction plate 13 is fitted. At this time, the adhesive is stretched on the bottom surface of the groove 14, the end surface (lower end surface) of the magnetic attraction plate 13, and the gaps 15 and 16 (see FIG. 2). In this state, the magnetic suction plate 13 is temporarily fixed in the groove 14. In this state, the magnetic attraction plate 13 is fitted into the groove 14 with a tightness equivalent to an intermediate spring, and the magnetic attraction plate 13 does not move inside the groove 14 during the curing process of the adhesive.

  Once the magnetic suction plate 13 is temporarily fixed in the groove 14, it is heated in a drying furnace to cure the adhesive. At this time, since the magnetic attraction plate is temporarily fixed to the groove 14 by the fitting structure using the protruding portions 13a and 13b, the displacement of the magnetic attraction plate 13 according to the curing of the adhesive is suppressed. Further, since the gaps 14 and 15 function as an adhesive reservoir, the adhesive is evenly distributed and a strong and stable fixing structure is obtained. In addition, as an adhesive, in addition to an adhesive that exhibits an adhesive force by drying, other forms of an adhesive such as a UV curable adhesive or an anaerobic adhesive may be used.

  When the magnetic attraction plate 13 is temporarily fixed in the groove 14, an adhesive is injected into the gaps 14 and 15 (see FIG. 2), and then the adhesive is cured. At this time, since the magnetic attraction plate is temporarily fixed to the groove 14 by the fitting structure using the protruding portions 13a and 13b, the displacement of the magnetic attraction plate 13 according to the curing of the adhesive is suppressed. Further, since the gaps 14 and 15 function as an adhesive reservoir, the adhesive is evenly distributed and a strong and stable fixing structure is obtained.

(Superiority)
In the present embodiment, a plurality of minute protrusions 13 a and 13 b protruding in the radial direction are provided on the outer peripheral side and the inner peripheral side of the magnetic attraction plate 13. The protrusions 13a and 13b are fitted to the wall surface of the annular groove 14 on the base plate 2 side, and the magnetic suction plate is further pressed by the adhesive pushed out to the bottom surface of the groove 14, the end surface of the suction plate, and the gaps 15 and 16. 13 is fixed to the groove 14. Further, sag portions 17 and 18 formed at the time of punching are provided on the same end face side (base plate side) of the protruding portions 13a and 13b. The magnetic attraction plate 13 is pushed into the groove 14 from the sag portions 17 and 18 side.

  Here, the protrusions 13a and 13b are provided for temporarily fixing the magnetic attraction plate 13 in the groove 14 until the adhesive pushed to the bottom surface of the groove 14, the end surface of the suction plate and the gaps 15 and 16 is cured. It functions as a fixing means.

  According to the above configuration, since the contact portion with the wall of the groove 14 is fixed with a tightening margin that can be temporarily fixed, the magnetic attractive plate to the groove 14 is not deformed without causing deformation of the thin magnetic attractive plate 13. 13 fittings can be performed. Further, the magnetic attraction plate 13 can be fixed to the base plate 2 with high positional accuracy without using a fixing jig while being fixed using an adhesive.

  In particular, since the protrusions 13a and 13b are provided on the outer side and the inner side, and the positions in the circumferential direction coincide with each other, the force applied to the protrusion 13a from the inner wall of the groove 14 and the outer wall of the groove 14 The force applied to the protruding portion 13b is effectively offset, and the magnetic attraction plate 13 is prevented from being distorted.

  By inserting the magnetic attraction plate 13 into the groove 14 of the base plate 2 from the side of the projecting portions 13a and 13b where the sag portions 17 and 18 are present, the fitting and fixing are facilitated, and the material is scraped at the fitting portion. This prevents the generation of dust.

(Modification)
FIG. 5 shows a top view of a modified example corresponding to FIG. 2, and FIG. 6 shows a partially enlarged view. In this case, the magnetic attraction plate 13 can be an ellipse having a major axis in the Y-axis direction and a minor axis in the X-axis direction orthogonal to the Y-axis.

  In this case, the annular magnetic attraction plate 13 has a long diameter portion and a short diameter portion that are orthogonal to each other, and the portion of the reference numeral 13b on the Y axis becomes a protruding portion on the outer peripheral side of the long diameter portion, and the reference numeral 13a on the Y axis The portion becomes a protruding portion on the inner peripheral side in the long diameter portion. Further, the portion denoted by reference numeral 13b on the X-axis serves as a protruding portion on the outer peripheral side in the short diameter portion, and the portion denoted by reference numeral 13a on the X-axis serves as a protruding portion on the inner peripheral side in the short diameter portion.

  When the approximate outer diameter of the magnetic attraction plate 13 is about 15 mm to 25 mm, the distance (outer diameter) between the tips of the two protruding portions of the portion 13 on the X axis and the portion 13 on the Y axis. The difference from the distance (outer diameter) between the tips of the two projecting portions of the portion is on the order of several μm to several tens of μm, and is actually an ellipse close to a perfect circle.

  In this structure, the inner protruding portion 13a contacts the inner wall of the groove 14 at the portions 32 and 34, and does not contact the inner wall of the groove 14 at the portions 31 and 33. Further, the outer protruding portion 13b is in contact with the outer wall of the groove 14 at the portions denoted by reference numerals 21 and 23, and is not in contact with the outer wall of the groove 14 at the portions denoted by reference numerals 22 and 24. That is, the protruding portion 13b on the Y axis provided on the outer peripheral side of the long diameter portion is in contact with the outer peripheral wall of the annular groove 14, and the protruding portion 13a on the Y axis provided on the inner peripheral side of the long diameter portion is It does not contact the inner peripheral wall of the annular groove 14. Further, the protruding portion 13b on the X axis provided on the outer peripheral side of the short diameter portion does not contact the outer peripheral wall of the annular groove 14, and protrudes on the X axis provided on the inner peripheral side of the short diameter portion. The part 13 a contacts the inner peripheral wall of the annular groove 14.

  In this structure, the elliptical magnetic attraction plate 13 is bent in the major axis direction, so that the state of fitting into the groove 14 is obtained. Further, the dimensions A and B shown in FIG. 6 are substantially the same dimensions, and the fitting into the groove 14 can be performed. And compared with the case of the structure of FIG. 2 where the magnetic attraction plate 13 is circular, reliable fitting can be performed even if the tightening margin is small.

  In addition, by making the magnetic attraction plate 13 into a perfect circle and making the annular groove 14 into an ellipse deviating from a perfect circle, the contact state between the protrusions 13a and 13b and the groove 14 similar to the case of FIG. it can. Further, the magnetic attraction plate 13 and the groove 14 are each made into a perfect circle, and the protrusions 13a and 13b and the groove 14 similar to the case of FIG. The contact state with can also be obtained. In the structure of FIG. 5, the major axis and the minor axis may not be orthogonal to each other, and may have a shape that intersects at an angle slightly shifted from 90 °.

(Other)
The protrusions 13a and 13b do not have to have the same shape and the same dimensions. The number of the protrusions 13a and 13b is not limited to four each, and a structure of three or more is possible. It is only necessary that at least two protrusions are fitted to the wall surface of the annular groove on the outer peripheral side and the inner peripheral side. The protrusions 13a and 13b are not necessarily arranged at the same position on the outer peripheral side and the inner peripheral side in the circumferential direction.

  The aspect of the present invention is not limited to the individual embodiments described above, and includes various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the contents described above. That is, various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof. The spindle motor of the present invention is not limited to a hard disk drive, but can be used for other magnetic disks, optical disks, magneto-optical disk drives, various fan drives, and the like.

  DESCRIPTION OF SYMBOLS 1 ... Spindle motor, 2 ... Base plate, 2a ... Ring-shaped convex part, 3 ... Stator core, 4 ... Coil winding, 5 ... Bearing part, 6a, 6b ... Dynamic pressure groove, 7 ... Shaft, 8 ... Bottom plate, 9 ... Hub DESCRIPTION OF SYMBOLS 10 ... Disk part, 11 ... Cylindrical part, 12 ... Rotor magnet, 13 ... Magnetic attraction board, 13a ... Inner protrusion, 13b ... Outer protrusion, 14 ... Groove, 15 ... Gap, 16 ... Gap, 17 ... Sagging part, 18 ... Saying part. 7a ... Flange

Claims (6)

A base plate;
A shaft body rotatably held on the base plate;
A stator core around which a coil winding is wound and fixed to the base plate;
A rotor member fixed to the shaft body;
A rotor magnet fixed to a portion of the rotor member facing the stator core in the radial direction;
An annular magnetic attraction plate attached to the base plate, disposed opposite to the rotor magnet in the axial direction, and generating a magnetic attraction force with respect to the rotor magnet;
The base plate is provided with an annular groove for holding the annular magnetic attraction plate,
The annular magnetic attraction plate is fixed to the annular groove of the base plate by an adhesive,
A plurality of protrusions are provided on each of the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate,
A spindle motor characterized in that at least two of the plurality of protrusions are fitted to the wall surface of the annular groove on the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate, respectively. The plurality of protrusions on each of the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate are:
2. The spindle motor according to claim 1, wherein three or more are provided at equiangular positions in the circumferential direction, and are arranged at the same position on the outer circumferential side and the inner circumferential side in the circumferential direction. The plurality of protrusions on each of the outer peripheral side and the inner peripheral side of the annular magnetic attraction plate have a sag portion on the same side in the axial direction,
3. The spindle motor according to claim 1, wherein the annular magnetic attraction plate is fitted into the annular groove from the side where the sag portion is located.   When viewed from the axial direction, the apex of the protrusion on the outer peripheral side of the magnetic attraction plate is inside the outer diameter of the rotor magnet, and the apex of the protrusion on the inner peripheral side of the magnetic attraction plate is the inner diameter of the rotor magnet The spindle motor according to any one of claims 1 to 3, wherein the spindle motor is further outside.   5. The spindle motor according to claim 1, wherein a gap between a wall surface of the annular groove and the annular magnetic attraction plate is filled with the adhesive. 6. The annular magnetic attraction plate has a first diameter portion and a second diameter portion that intersect,
The protrusion is provided on each of the outer peripheral side of the first diameter part and the inner peripheral side of the second diameter part,
The protrusion provided on the outer peripheral side of the first diameter portion is in contact with the outer peripheral side wall of the annular groove,
The inner peripheral side of the first diameter portion is not in contact with the inner peripheral wall of the annular groove,
The outer peripheral side of the second diameter portion is not in contact with the outer peripheral wall of the annular groove,
6. The spindle according to claim 1, wherein a protrusion provided on an inner peripheral side of the second diameter portion is in contact with an inner peripheral wall of the annular groove. motor.

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