JP2013070609A - Motor and disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor for reducing vibration of a rotary part by enhancing parallelism of a yoke.SOLUTION: A yoke 35 is fixed with adhesive on an upper face of a second recess of a circular recessed portion 312 of a base 31. The second recess comprises a first face in contact with a lower face of the yoke 35, and a second face having a gap in an axial direction with the lower face of the yoke 35. An outer peripheral edge and an extending portion of the yoke 35 are provided opposite to the second face, via a gap, in the axial direction.

Description

  The present invention provides a motor for reducing vibration by applying an axial magnetic force to a rotating body including a rotor magnet by making a magnetic body and a rotor magnet face each other in an axial direction, and The present invention relates to a disk drive equipped with this motor.

Conventionally, there is a configuration in which a yoke made of a magnetic material is arranged at a position facing an end surface of a rotor magnet as one of means for reducing the force that floats the rotating portion of the motor generated by the rotation of the motor. . With this configuration, the magnetic attraction force between the end surface of the rotor magnet and the yoke becomes a resistance against the force that causes the rotating portion to float (see Patent Document 1, for example, as such a conventional motor structure).
No. 2006-194400

  When the yoke is attached to the rotor magnet at an angle, the magnetic attraction force becomes unbalanced, causing the rotating portion to vibrate. In particular, in a spindle motor that rotates a recording disk using a magnetic head, since the gap between the recording disk and the magnetic head is very small, the recording disk and the magnetic head may come into contact with each other due to vibration of the rotating part. There is. Therefore, it is important to reduce the vibration of the rotating part by making the mounting parallelism with respect to the base of the yoke highly accurate.

  Further, due to the recent decrease in the price of the disk drive device, there is an increasing demand for a decrease in the price of the motor mounted on the disk drive device.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to reduce the vibration of the rotating part by improving the parallelism of the yoke, and a disk drive device equipped with this motor. Is provided at low cost.

An exemplary motor of the first invention of the present invention is:
A rotating part including a rotor magnet that rotates around a predetermined central axis;
A stator that generates a magnetic field and is disposed opposite to the rotor magnet, holds the stator, and has a base having an upper surface that faces the rotating portion in the axial direction, and is fixed at a position facing the rotor magnet on the upper surface of the base in the axial direction. A fixed portion including a yoke formed of a magnetic material to be
A bearing mechanism that is formed between the rotating part and the fixed part, and rotatably supports the rotating part;
With
The yoke has an inner edge and an outer edge;
On the upper surface of the base facing the yoke in the axial direction,
A first surface in contact with the yoke;
Formed on the lower side in the axial direction than the first surface, and having a yoke and a second surface having a gap in the axial direction,
At least a part of the first surface is opposed to the rotor magnet in the axial direction,
The yoke has a flat plate portion facing the rotor magnet in the axial direction,
A substantially axially extending portion formed on at least one of the inner edge and the outer edge of the yoke,
The extension portion extends toward the second surface, and the axial end surface of the extension portion faces the second surface in the axial direction with a gap therebetween.

An exemplary motor of the second invention of the present invention is:
A rotating part including a rotor magnet that rotates around a predetermined central axis;
A stator that is disposed opposite to the rotor magnet and that generates a magnetic field and holds the stator, and has a base having an upper surface that faces the rotating portion in the axial direction, and is fixed at a position facing the rotor magnet on the upper surface of the base in the axial direction. A fixed portion including a yoke formed of a magnetic material,
A bearing mechanism that is formed between the rotating part and the fixed part and rotatably supports the rotating part;
With
The yoke has an inner edge and an outer edge;
On the upper surface of the base facing the yoke in the axial direction,
A first surface in contact with the yoke;
Formed on the lower side in the axial direction than the first surface, and having a yoke and a second surface having a gap in the axial direction,
At least a part of the first surface is opposed to the rotor magnet in the axial direction,
The yoke has a flat plate portion facing the rotor magnet in the axial direction,
A substantially axially extending portion formed on at least one of the inner edge and the outer edge of the yoke,
The extension extends toward the second surface,
An adhesive is interposed between the lower surface of the flat plate portion and the upper surface of the first surface, and between the extension portion and the second surface.

  ADVANTAGE OF THE INVENTION According to this invention, the motor which reduces the vibration of a rotation part by improving the parallelism of a yoke, and the disk drive device carrying this motor can be provided at low cost.

  Further, the yoke can be firmly fixed to the base.

It is the schematic cross section cut in the axial direction which showed one form of the Example of the motor of this invention. 1 shows one embodiment of a yoke mounted on a motor of the present invention, wherein a) is a schematic cross-sectional view of the yoke cut in the axial direction, and b) is a schematic plan view of the yoke viewed from the upper side in the axial direction. C) is a schematic plan view of the yoke viewed from the lower side in the axial direction. It is the schematic diagram which showed the state of the electric nickel plating of the yoke of this invention. It is the schematic diagram which showed the metal mold | die of the press work which forms the yoke of this invention. It is the schematic cross section cut in the axial direction which showed a part of one form of the Example of the base mounted in the motor of this invention. It is the schematic cross section cut in the axial direction which showed the state which has arrange | positioned the yoke to the base of this invention. It is an enlarged view of the dotted line circle of FIG. It is the schematic cross section cut in the axial direction which showed one form of the Example of the disk drive unit of this invention. It is a schematic cross section which showed another form of the structure which arrange | positions a yoke in the base in the motor of this invention.

<Motor structure>
One embodiment of the motor structure of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view, cut in the axial direction, showing one embodiment of the motor of the present invention.

  Referring to FIG. 1, a motor 10 includes a rotating unit 20 including a rotor magnet 24 that rotates around a predetermined central axis J1, a stator 32 and a stator 32 that face the rotor magnet 24 in a radial direction and generate a magnetic field. The fixed part 30 which has the base 31 which hold | maintains, and the bearing mechanism BR formed between the rotation part 20 and the fixed part 30 are provided.

  The rotating unit 20 is disposed coaxially with the central axis J1, is fixed to the shaft 21 that rotates about the central axis J1, and is fixed to the upper portion of the shaft 21, and mounts a member to be rotated (recording disk in this embodiment). A rotor hub 22 having a mounting portion 224, a rotor yoke 23 fixed to the rotor hub 22, and a rotor magnet 24 fixed to the rotor yoke 23 are provided.

  The shaft 21 is formed in a substantially cylindrical shape. And the lower end part of the shaft 21 has the enlarged diameter part 211 with a large diameter compared with the other site | part of the shaft 21. As shown in FIG.

  The rotor hub 22 is formed on the lower side in the axial direction than the shaft fixing portion 221, which is fixed to the shaft 21. The lid portion 222 covers the upper side of the stator 32, and is axially lower than the outer periphery of the lid portion 222. A cylindrical portion 223 that extends to the side, and a placement portion 224 that has a placement surface on which the recording disk is placed by extending radially outward from the cylindrical portion 223. A rotor yoke 23 in which a magnetic steel plate is formed in a substantially cylindrical shape is fixed to the inner peripheral surface of the cylindrical portion 223 of the rotor hub 22. A cylindrical rotor magnet 24 is fixed to the inner peripheral surface of the rotor yoke 23.

  The fixing portion 30 has a substantially cylindrical sleeve 33 having an inner peripheral surface penetrating in the axial direction facing the outer peripheral surface of the shaft 21, and a disk-shaped plate 34 that covers the inner peripheral surface of the sleeve 33 from below. A base 31 having an axially penetrating holding cylindrical portion 311 having an inner peripheral surface for fixing the outer peripheral surface of the sleeve 33, and a stator 32 having an inner peripheral surface fixed to the outer peripheral surface of the holding cylindrical portion 311 of the base 31. And comprising.

  The base 31 includes a holding cylindrical portion 311, a circular concave portion 312 that is a circular concave portion that extends radially outward from the holding cylindrical portion 311, and a flat plate portion 313 that extends further radially outward from the circular concave portion 312. The inner peripheral surface of the circular recess 312 faces the outer peripheral surface of the mounting portion 224 of the rotor hub 22 in the radial direction. A yoke 35 formed of an annular magnetic material is fixed at a radial position opposite to the lower end surface of the rotor magnet 24 in the circular recess 312 in the axial direction.

  The holding cylindrical portion 311 has an annular shape on which the stator 32 is mounted, and a stator mounting surface 3111 that is a flat surface extending in the radial direction, and extends axially above the stator mounting surface 3111. It has a first outer peripheral surface 3112 that is an outer peripheral surface that faces the inner peripheral surface in the radial direction, and a second outer peripheral surface 3113 that extends downward from the stator mounting surface 3111 in the axial direction and continues to the circular recess 312. The diameter of the first outer peripheral surface 3112 is smaller than the diameter of the second outer peripheral surface 3113.

  The stator 32 has a stator core 321 having a through hole that forms an inner peripheral surface of the stator 32 formed by laminating thin steel plates of magnetic material in a plurality of axial directions, and a plurality of conductive wires are wound around the stator core 321. The coil 322 is formed. The outer surface of the stator core 321 faces the inner peripheral surface of the rotor magnet 24 in the radial direction.

  The sleeve 33 includes an inner circumferential surface 331 that faces the outer circumferential surface of the shaft 21, a first housing recess 332 that houses the diameter-enlarged portion 211 of the shaft 21 and has an inner circumferential surface with a diameter larger than the diameter of the inner circumferential surface 331. A second receiving recess 333 formed on the lower side in the axial direction than the first receiving recess 332 and receiving the plate 34 and having an inner peripheral surface having a diameter larger than that of the inner peripheral surface of the first receiving recess 332. . Thereby, the enlarged diameter portion 211 of the shaft 21 is opposed to the lower surface of the first housing recess 332 and the upper surface of the plate 34 in the axial direction.

  Further, two radial dynamic pressure generating grooves 3311 that are spaced apart in the axial direction are formed on the inner peripheral surface 331 of the sleeve 33. A thrust dynamic pressure generating groove 3321 is formed on the lower surface of the first housing recess 332 and the upper surface of the plate 34. The space between the sleeve 33 and the plate 34 and the shaft 21 is filled with lubricating oil. The shaft 21 is rotatably supported in the axial direction and the radial direction by the dynamic pressure generated in the radial dynamic pressure generating groove 3311 and the thrust dynamic pressure generating groove 3321 as the shaft 21 rotates. The radial dynamic pressure generating groove 3311, the thrust dynamic pressure generating groove 3321, and the lubricating oil constitute a bearing mechanism BR.

  By passing a current through the coil 322 of the stator 32, a magnetic field is generated around the stator 32. Then, by forming a rotating magnetic field by this magnetic field and the rotor magnet 24, the rotating unit 20 obtains a rotational driving force centered on the central axis J1.

<Shape of yoke 35>
Next, the shape of the yoke 35 of the motor 10 of this invention is demonstrated using FIG. 2 and FIG. 2A is a schematic cross-sectional view of the yoke 35 cut in the axial direction, b) is a schematic plan view of the yoke 35 viewed from the upper side in the axial direction, and c) is a lower side of the yoke 35 in the axial direction. It is the model top view seen from the side. FIG. 3 is a schematic diagram showing a state where the electric nickel plating of the yoke 35 is performed. FIG. 4 is a schematic view showing a part of a press mold for forming a yoke from a steel plate.

  Referring to FIG. 2, the yoke 35 is formed by pressing a magnetic steel plate. The yoke 35 includes a flat plate portion 351 that is an annular flat plate, and an extension portion 352 that extends in the axial direction from the inner peripheral side of the flat plate portion 351. A bent portion 353 is formed between the flat plate portion 351 and the extension portion 352. By using the bent portion 353 and the extended portion 352, the strength of the yoke 35 can be improved as compared with the case where only the flat plate portion 351 is provided. Therefore, the plate thickness of the yoke 35 can be reduced.

  In addition, since the extension 352 is formed, the operator can easily handle the yoke 35 having a thin plate thickness. That is, the worker can have the yoke 35 starting from the extension 352. Therefore, the workability of manufacturing the motor of the operator can be improved.

  Referring to FIG. 3, electric nickel plating 354 is applied to the entire outer surface of yoke 35 on yoke 35. In the electro nickel plating 354, the thickness of the outer peripheral surface of the flat plate portion 351 and the axial end surface of the extension portion 352 are larger than those of other portions (hereinafter, the thickness of the outer peripheral side of the flat plate portion 351). The second film is a portion where the thickness of the first film thickness portion 3541 is thicker than that of the other portion and the thickness of the axial end surface of the extension portion 352 is thicker than that of the other portion. Thick part 3542).

  By applying the electric nickel plating 354 to the entire outer surface of the yoke 35, contact between the inner yoke 35 and the outside air (air) can be prevented from the electric nickel plating 354. Therefore, generation | occurrence | production of the rust of the yoke 35 can be prevented. Therefore, a highly reliable motor can be provided.

  4A, the press die 40 is movable in the axial direction, and includes a first die 41 having a punch 411 that is an upper blade that is punched from the steel plate 35a into the outer shape of the yoke 35, and the punch And a second mold 42 having a die 421 which is a lower blade for holding the steel plate 35a with respect to the axial force of 411. In the present embodiment, the first mold 41 is disposed on the upper side with respect to the second mold 42. Then, the outer peripheral edge of the steel plate 35 a corresponding to the outer peripheral surface of the flat plate portion 351 of the yoke 35 is cut by the punch 411 of the first mold 41. 4B), the cylindrical portion 35a1 is formed by squeezing the center of the annular steel plate 35a upward by the squeezing punch 421 of the second mold. By cutting the cylindrical portion 35a1 in a plane perpendicular to the extending direction of the cylindrical portion 35a1, an extended portion 352 is formed (the cut portion is a dotted line portion in FIG. 4B). As a result, the steel plate 35 a has the shape of the yoke 35. Further, the surface on the side punched by the punch 411 corresponding to the upper surface of the steel plate 35a is the surface on the side where the yoke 35 is punched.

  Here, when the steel plate 35a is punched by the punch 411 of the first mold 41, the back surface of the punched surface corresponding to the lower surface of the steel plate 35a is substantially the same as the direction in which the punch 411 pulls out the steel plate 35a. Burr may occur in the direction.

  Here, the cylindrical portion 35a1 can be formed without deforming the annular flat plate portion of the steel plate 35a by drawing the steel plate 35a with the punch 421 of the second mold 42. Further, by drawing the steel plate 35a with the second die 41, the drawing can be performed while securing the positional accuracy of the steel plate 35a even after being punched with the first die 41.

  The electro nickel plating 354 is preferably applied after the yoke 35 is formed by press working. When a steel plate that has been pre-plated with nickel electroplated 354 is punched into the shape of the yoke 35 by pressing, the outer peripheral surface of the flat plate portion 351 and the axial end surface of the extension portion 352 of the yoke 35 are processed surfaces. The surface is not subjected to nickel plating 354. Therefore, there is a possibility that rust is generated when these processed surfaces come into contact with the outside air. Further, when the nickel electroplating is performed again in order to prevent the processing surface from being rusted, the number of steps for forming the yoke 35 is increased. As a result, the motor manufacturing process increases, and the motor cannot be provided at a low cost. Therefore, after the yoke 35 is formed by press working, by applying the electric nickel plating 354, the yoke 35 in which the generation of rust is prevented can be provided at a low cost. As a result, a highly reliable motor can be provided at low cost.

<Shape in circular recess 312>
Next, the shape of the circular recess 312 in the base 31 of the motor 10 of the present invention will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view showing a portion of the base 31 shown in FIG.

  Referring to FIG. 5, the circular concave portion 312 is formed on the inner side in the radial direction from the first concave portion 3121 and the annular first concave portion 3121 which is the upper surface facing the lower surface of the mounting portion 224 of the rotor hub 22 in the axial direction. An annular second recess 3122 that is an upper surface to which the yoke 35 is fixed, and an annular third recess 3123 that is formed radially inward of the second recess 3122 and faces the coil 322 of the stator 32 in the axial direction. . The upper surface of the first recess 3121 is formed on the upper side in the axial direction from the upper surface of the second recess 3122. The upper surface of the second recess 3122 is formed on the upper side in the axial direction from the upper surface of the third recess 3123.

  The second recess 3122 is formed on the first surface 3122a in contact with the lower surface of the yoke 35 and on both sides in the radial direction of the first surface 3122a, and is formed so as to be lower in the axial direction than the first surface 3122a. Two surfaces 3122b. The second surface 3122b includes an inner second surface 3122b1 formed radially inward of the first surface 3122a and an outer second surface 3122b2 formed radially outward of the first surface 3122a. Here, the inner second surface 3122b1 is formed to be lower in the axial direction than the outer second surface 3122b2. The inner second surface 3122b1 is formed to be axially lower than the upper surface of the third recess 3123. An annular peripheral surface 3121a extending along the axial direction is formed between the outer second surface 3122b2 and the first recess 3121.

  The base 31 of the present invention is formed by casting aluminum or an aluminum alloy using a die casting method or the like. Thereby, even if the shape of the base 31, especially the shape of the circular recessed part 312 becomes complicated, the shape can be formed easily.

<Relationship between yoke 35 and circular recess 312>
Next, the positional relationship between the yoke 35 of the present invention and the circular recess 312 of the base 31 will be described with reference to FIG. FIG. 6 is a schematic cross-sectional view taken along the axial direction, showing a state in which the yoke 35 is disposed in the circular recess 312 of the base 31.

  Referring to FIG. 6, the lower surface (surface on the punching side) of flat plate portion 351 of yoke 35 is fixed to the upper surface of first surface 3122a via an adhesive. The outer peripheral portion of the flat plate portion 351 is opposed to the outer second surface 3122b2 in the axial direction. In particular, the outer peripheral portion of the flat plate portion 351 includes a first film thickness portion 3541 of the electric nickel plating 354. Here, the upper surface of the outer second surface 3122b2 has a gap in the axial direction from the lower surface of the outer peripheral portion of the flat plate portion 351. Further, the lower surface of the inner peripheral portion of the flat plate portion 351, the bent portion 353, and the axial end surface (lower end surface) of the extension portion 352 face the inner second surface 3122b1 in the axial direction. Here, the upper surface of the inner second surface 3122b1 has a gap in the axial direction with respect to the lower surface of the inner peripheral portion of the flat plate portion 351, the bent portion 353, and the axial end surfaces of the extension portion 352.

  With the above configuration, the lower surface of the first film thickness portion 3541 and the lower surface of the second film thickness portion 3542 of the electric nickel plating 354 face the outer second surface 3122b2 and the inner second surface 3122b1, respectively, with a gap in the axial direction. Therefore, the first film thickness portion 3541 and the second film thickness portion 3542 can prevent the yoke 35 from being inclined with respect to the first surface 3122 a that is the upper surface of the base 31. Therefore, since the gap between the lower end surface of the rotor magnet 24 and the upper surface of the yoke 35 becomes uniform with high accuracy, the magnetic attraction between the yoke 35 and the rotor magnet 24 due to the inclination of the yoke 35 is caused. It is possible to reduce the vibration of the rotating unit 20 and the noise caused by this vibration. Therefore, a motor with reduced vibration and noise can be provided.

  Moreover, even if a burr extending downward in the axial direction is generated on the outer peripheral surface of the flat plate portion 351 of the yoke 35 by forming the yoke 35 by a different pressing method with the above configuration, the flat plate portion of the yoke 35 is formed. Since a gap is provided between the outer peripheral portion of 351 and the upper surface of the outer second surface 3122b2, it is possible to prevent the burr from contacting the upper surface of the outer second surface 3122b2. Even if a burr extending radially outward occurs on the axial end surface of the extension 352, the axial end surface of the extension 352 and the inner second surface 3122b1 face each other in the radial direction and the axial direction with a gap therebetween. Therefore, it is possible to prevent the burr and the inner second surface 3122b1 from contacting each other. Therefore, it is possible to prevent the yoke 35 from being inclined with respect to the first surface 3122 a that is the upper surface of the base 31 due to burrs generated on the outer peripheral surface of the flat plate portion 351 of the yoke 35 and the axial end surface of the extension portion 352. Therefore, since the gap between the lower end surface of the rotor magnet 24 and the upper surface of the yoke 35 becomes uniform with high accuracy, the magnetic attraction between the yoke 35 and the rotor magnet 24 due to the inclination of the yoke 35 is caused. It is possible to reduce the vibration of the rotating unit 20 and the noise caused by this vibration. Therefore, a motor with reduced vibration and noise can be provided.

  Further, the peripheral surface 3121a of the base 31 faces the outer peripheral surface of the flat plate portion 351 of the yoke 35 in the radial direction. The peripheral surface 3121a is formed so as to be axially above the upper surface of the flat plate portion 351 of the yoke 35.

  Further, the adhesive applied to the upper surface of the first surface 3122a comes into contact with the lower surface of the flat plate portion 351 of the yoke 35, so that a part of the adhesive moves to the inner second surface 3122b1 and the outer second surface 3122b2. To do. By providing the inner second surface 3122b1 and the outer second surface 3122b2, extra adhesive can be removed from the first surface 3122a by pressing the yoke 35 against the first surface 3122a. Therefore, the adhesive between the yoke 35 and the first surface 3122a can be made uniform. As a result, the tilt of the yoke 35 with respect to the base 31 can be prevented, and a motor capable of reducing the vibration of the rotating portion 20 and the noise caused by this vibration can be provided.

  Further, an adhesive is filled between the inner second surface 3122 b 1 and the outer second surface 3122 b 2 and the lower surface of the yoke 35. Thus, the yoke 35 is also fixed to the base 31 more firmly because it is also fixed to the inner second surface 3122b1 and the outer second surface 3122b2. Therefore, even when an impact or the like is received from the outside of the motor 10, the yoke 35 can be prevented from being separated from the base 31. Therefore, a highly reliable motor can be provided.

  Here, the adhesive filled between the inner second surface 3122b1 and the outer second surface 3122b2 and the lower surface of the yoke 35 may cover the outer peripheral surface of the flat plate portion 351 and the axial end surface of the extension portion 352. Thus, even if the formed yoke 35 is used by pressing a steel plate that has been pre-plated with nickel, the outer peripheral surface of the flat plate portion 351 and the axial end surface of the extension portion 352 are covered with an adhesive. Therefore, generation | occurrence | production of rust can be suppressed. Therefore, it is possible to use an inexpensive yoke as compared with the yoke 35 to be electroplated later. Therefore, a highly reliable motor can be provided at low cost. In particular, the circumferential surface 3121a that faces the flat plate portion 351 of the yoke 35 in the radial direction is provided to the upper side in the axial direction from the upper surface of the flat plate portion 351, so An adhesive reservoir can be provided. Therefore, the outer peripheral surface of the flat plate portion 351 can be more reliably covered with the adhesive. As a result, generation of rust on the yoke 35 can be suppressed.

<Relationship Between Yoke 35 and Rotor Magnet 24>
Next, the positional relationship between the yoke 35 and the rotor magnet 24 of the present invention will be described with reference to FIG. FIG. 7 is an enlarged view of the dotted circle in FIG.

  Referring to FIG. 7, first surface 3122 a of base 31 includes a portion facing the lower end surface of rotor magnet 24 in the axial direction. Thus, the gap between the lower end surface of the rotor magnet 24 and the upper surface of the flat plate portion 351 of the yoke 35 can be made uniform with high accuracy.

  Further, the yoke 35 extends radially inward from the inner peripheral surface of the rotor magnet 24. The yoke 35 extends from the outer peripheral surface of the rotor magnet 24 to the radially outer side and the outer peripheral surface of the rotor yoke 25. Thereby, even if the plate thickness of the yoke 35 is reduced, the magnetic saturation of the yoke 35 can be prevented because the radial width of the yoke 35 is increased. Thereby, the iron loss of the yoke 35 can be prevented. This is particularly suitable when the motor 10 is rotated at a high speed.

<Structure of disk drive>
Next, an embodiment of a disk drive device equipped with the motor 10 of the present invention will be described with reference to FIG. FIG. 8 is a schematic cross-sectional view taken along the axial direction, showing an embodiment of the disk drive device of the present invention.

  Referring to FIG. 8, the disk drive device 50 includes a housing 51 having a rectangular shape. The inside of the housing 51 forms a clean space with extremely little dust. Inside, a motor 54 on which a hard disk 52, which is a disk-shaped recording disk for recording information, is mounted.

  An access mechanism 53 that reads / writes information from / to the hard disk 52 is disposed inside the housing 51. The access mechanism 53 includes a magnetic head 531 that reads and writes information on the hard disk 52, an arm 532 that supports the magnetic head 531, and an actuator unit 533 that moves the magnetic head 531 and arm 532 to a required position on the hard disk 52. Is done.

  By applying the motor 10 of the present invention as the motor 54 of such a disk drive device 50, the vibration of the rotating unit 20 caused by the yoke 35 and the noise caused by this vibration can be reduced. In addition, a disk drive device with low noise can be provided. Further, the yoke 35 can be thinned by increasing the radial width of the yoke 35, and the upper limit of the magnetic saturation of the yoke 35 can be improved. it can. In particular, this is preferably applied to a disk drive device for a server where high speed rotation of the motor 10 is required.

  As mentioned above, although one form of the Example of this invention was demonstrated, this invention is not limited to this, A various deformation | transformation is possible within a claim.

  For example, in the motor 10 of the present invention, the inner second surface 3122b1 facing the extension 352 of the yoke 35 in the axial direction is provided separately from the upper surface of the third recess 3123, but the present invention is limited to this. There is no. For example, as illustrated in FIG. 9, the inner second surface 3122 b 1 may not be provided, and the third recess 3123 may serve as the inner second surface 3122 b 1.

  Further, for example, in the yoke 35 of the present invention, the electric nickel plating 354 is used for the rust prevention treatment, but the present invention is not limited to this. For example, electroless nickel plating conventionally used may be used. In this case, the price for manufacturing the yoke 35 is higher than that of the electric nickel plating.

  In this embodiment, by reducing the contact area between the upper surface of the base and the yoke, it is possible to prevent deterioration of the parallelism in the circumferential direction and the radial direction of the yoke due to the contact between the base and the yoke. That is, the inclination of the yoke in the circumferential direction and the radial direction with respect to the base can be reduced. As a result, since the gap between the yoke and the rotor magnet can be made substantially constant, the vibration caused by the inclination of the yoke in the rotating portion and the noise caused by this vibration can be reduced.

  Further, by forming the second surface on at least one of the inner edge and the outer edge, it is possible to improve the mounting parallelism of the yoke as compared with the case where the inner edge and the outer edge are in contact with the first surface.

  Further, by forming the second surface on the inner edge and the outer edge, it is possible to prevent contact between the burr and the base generated on the inner edge and the outer edge by processing the yoke. Accordingly, it is possible to improve the mounting parallelism of the yoke with respect to the base. That is, the inclination of the yoke with respect to the base can be prevented.

  Further, the yoke includes a flat plate portion that faces the rotor magnet in the axial direction, and an extension portion that is formed on at least one of the inner edge and the outer edge of the yoke and extends in the substantially axial direction.

  Thereby, the extension part extended in a substantially axial direction is formed in at least one of an inner edge and an outer edge, and the intensity | strength of yoke itself can be improved. Therefore, even if the yoke is thinned, the strength necessary for the yoke can be maintained, so that the yoke can be thinned. In addition, when the yoke is thinned, the operator can easily hold the yoke. Therefore, the operator can easily handle the yoke. Therefore, the workability of the worker can be improved.

  In addition, since the extension of the yoke extends to the second surface, the yoke can be thinned and the axial gap between the rotating body and the yoke can be reduced.

  The yoke is formed by pressing a steel plate. Thereby, the yoke can be manufactured at low cost. Therefore, the motor can be provided at low cost.

  Further, since the surface of the yoke to be punched by pressing is a surface facing the rotor magnet, the surface on the opposite side is a surface where burrs may occur. Then, even if burrs are generated when the opposite surface of the upper surface of the base facing the peripheral edge of the yoke is the second surface, the burrs are accommodated in the space between the second surface and the yoke. be able to. Therefore, it is possible to provide a yoke with improved mounting parallelism that is free from the influence of burrs with respect to the base.

  Further, by applying electro nickel plating to the yoke, it is possible to prevent the rust of the yoke itself and to reduce the cost compared to electroless nickel plating generally used conventionally. . Therefore, the motor can be provided at low cost.

  Electro nickel plating may increase the film thickness of the inner and outer edges, but by forming a second surface on the inner and outer edges, the tilt of the yoke due to uneven film thickness can be prevented. can do.

  In addition, the nickel electroplating can be performed on the punched surface by applying the nickel electroplating after pressing the yoke. Therefore, generation | occurrence | production of the rust of a yoke can be reduced more reliably and omission of a burr | flash can also be prevented reliably. Therefore, a highly reliable motor can be provided.

  Moreover, the yoke can be provided at a lower cost by applying electro nickel plating in advance, that is, by using a plated steel plate. Therefore, the motor can be provided at a lower cost.

  Further, in the rust-preventing thin film, the portion having a larger film thickness than the other part and the second surface are opposed in the axial direction, thereby avoiding contact between the first surface and the thick film portion. . Therefore, the yoke can be prevented from tilting.

  Further, since the second surface includes a surface facing the stator in the axial direction, the stator can be disposed further on the lower side in the axial direction. Therefore, the motor can be thinned.

  Moreover, the yoke can be firmly fixed to the base by filling the adhesive between the second plane and the yoke. Therefore, even if the contact area between the base and the yoke is reduced, it is possible to prevent a reduction in the fixing strength between the base and the yoke.

  Further, since the peripheral surface of the base is formed on the outer edge of the yoke, the adhesive can be favorably adhered to the outer edge of the yoke. Here, since the outer edge of the yoke is a cut-off cut surface, electric nickel plating is taken, and rust may be generated. However, since the cut surface is covered with the adhesive, it is possible to block contact with the outside air, so that generation of rust can be suppressed.

  Further, the first surface and the second surface can be easily formed by forming the base by casting. In particular, the shape of the base must be complicated by reducing the shape of the yoke. However, since the complicated shape can be easily formed by casting, the price of the entire motor can be reduced.

  In addition, since the yoke and the first surface of the base are fixed with an adhesive, the second surface can be used as a release portion of the adhesive. That is, part of the adhesive between the yoke and the first surface moves to the second surface side, whereby the thickness of the adhesive between the yoke and the base can be made uniform. Therefore, the inclination of the yoke with respect to the base can be reduced.

  In addition, since the motor according to the present invention is mounted to reduce the vibration caused by the yoke and the noise caused by the vibration, a disk drive device with reduced vibration and noise can be provided.

DESCRIPTION OF SYMBOLS 10 Motor 20 Rotating part 21 Shaft 22 Rotor hub 23 Rotor yoke 24 Rotor magnet 30 Fixed part 31 Base 312 Circular recessed part 3121 First recessed part 3121a Circumferential surface 3122 Second recessed part 3122a First surface 3122b Second surface 3122b1 Inside second surface 3122b2 Outside second Surface 3123 Third recess 32 Stator 33 Sleeve 34 Plate 35 Yoke 35a Steel plate 351 Flat portion 352 Extension portion 353 Bending portion 354 Electro nickel plating (thin film)
3541 1st film thickness part (film thickness part)
3542 Second film thickness part (film thickness part)
40 mold 50 disk drive device 51 housing 52 hard disk (recording disk)
53 Access mechanism 533 Actuator BR Bearing mechanism J1 Center shaft

Claims (15)

A motor,
A rotating part including a rotor magnet that rotates around a predetermined central axis;
A stator that generates a magnetic field, is disposed opposite to the rotor magnet, and a base that holds the stator and has an upper surface that faces the rotating portion in the axial direction, and is opposed to the rotor magnet on the upper surface of the base in the axial direction. A fixed portion including a yoke formed of a magnetic material fixed in a fixed position;
A bearing mechanism formed between the rotating part and the fixed part, and rotatably supporting the rotating part;
With
The yoke has an inner edge and an outer edge;
On the upper surface of the base facing the yoke in the axial direction,
A first surface in contact with the yoke;
The second surface having an axial gap between the yoke and the yoke;
At least a part of the first surface is opposed to the rotor magnet in the axial direction,
The yoke includes a flat plate portion facing the rotor magnet in the axial direction;
A substantially axially extending portion formed on at least one of the inner edge and the outer edge of the yoke,
The extension portion extends toward the second surface, and an axial end surface of the extension portion faces the second surface in the axial direction with a gap therebetween. The motor according to claim 1,
The yoke is formed by pressing a steel plate. The motor according to claim 2,
The motor according to claim 1, wherein a surface of the yoke that is punched out by a press mold is a surface that faces the rotor magnet. A motor according to any one of claims 1 to 3,
An electric nickel plating is applied to the yoke. The motor according to claim 4,
The yoke is formed by pressing,
The electric nickel plating is performed on the entire yoke after the yoke is pressed. The motor according to claim 5,
The yoke is formed by pressing,
The electric nickel plating is applied to the yoke before the yoke is pressed. A motor according to any one of claims 2 to 5,
The yoke is subjected to a rust prevention treatment for a thin film,
The motor according to claim 2, wherein the second surface is opposed to a portion of the thin film that is thicker than other portions in the axial direction. A motor according to any one of claims 1 to 7,
The motor according to claim 2, wherein the second surface includes a surface facing the stator in the axial direction. A motor,
A rotating part including a rotor magnet that rotates around a predetermined central axis;
A stator that generates a magnetic field, is disposed opposite to the rotor magnet, and a base that holds the stator and has an upper surface that faces the rotating portion in the axial direction, and is opposed to the rotor magnet on the upper surface of the base in the axial direction. A fixed portion including a yoke formed of a magnetic material fixed in a fixed position;
A bearing mechanism formed between the rotating part and the fixed part, and rotatably supporting the rotating part;
With
The yoke has an inner edge and an outer edge;
On the upper surface of the base facing the yoke in the axial direction,
A first surface in contact with the yoke;
The second surface having an axial gap between the yoke and the yoke;
At least a part of the first surface is opposed to the rotor magnet in the axial direction,
The yoke includes a flat plate portion facing the rotor magnet in the axial direction;
A substantially axially extending portion formed on at least one of the inner edge and the outer edge of the yoke,
The extension extends toward the second surface;
An electric motor is provided between the lower surface of the flat plate portion and the upper surface of the first surface, and between the extension portion and the second surface. The extension is formed on the inner edge of the yoke,
The second surface has an outer second surface and an inner second surface;
The motor according to claim 9, wherein the adhesive is interposed between an outer peripheral surface of the extension and the inner second surface.   The motor according to claim 10, wherein the adhesive covers an end surface in the axial direction of the extension portion.   The motor according to claim 10 or 11, wherein the adhesive is interposed between the second outer surface and the lower surface of the yoke. The extension is formed on an inner edge of the yoke.
The motor according to claim 9, wherein the adhesive covers an outer peripheral surface of the flat plate portion. The base is formed with a circumferential surface facing the outer edge of the yoke in the radial direction,
The peripheral surface is provided on the upper side in the axial direction from the upper surface of the flat plate portion,
The motor according to claim 13, wherein the adhesive is interposed between the peripheral surface and the upper surface of the flat plate portion. A motor according to any one of claims 1 to 14,
A recording disk mounted on the rotating unit;
An access mechanism for recording and reproducing information on the disc;
A disk drive device comprising:

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