JP4752273B2 - Spindle motor - Google Patents

Description

  The present invention relates to a spindle motor having a fluid dynamic pressure bearing device and a recording disk driving device on which the spindle motor is mounted.

  In recent years, mounting of a recording disk drive device to a portable device has progressed, and there is a strong demand for improvement in impact resistance and reliability as well as downsizing of the recording disk drive device. Accordingly, there is a demand for improvement in impact resistance and reliability of the spindle motor mounted on the recording disk drive. In order to meet this demand, the spindle motor has adopted a bearing system that uses fluid dynamic pressure instead of a ball bearing system (as a conventional example of such a fluid dynamic bearing system). For example, refer to Patent Document 1). However, there is a problem of scattering of the lubricating fluid at the gas-liquid interface formed at the boundary between the lubricating fluid and the outside air used in this fluid dynamic pressure bearing system, and the air present in the joint portion of the plurality of parts in contact with the lubricating fluid. And there was a new problem of replacement of lubricating fluid.

JP 2002-349550 A

  More specifically, referring to FIG. 1 of Patent Document 1, lubricating oil (corresponding to a lubricating fluid in the present invention) is interposed between the sleeve (5) and the main shaft (3) inserted through the sleeve (5). A radial bearing portion is formed, and a thrust flange (6) fixed to the main shaft (3) is surrounded by a concave portion of the sleeve (5) and a plate (8) attached to the sleeve (5) so as to close the concave portion. A space is formed and filled with lubricating oil to constitute a thrust bearing portion. Both the sleeve (5) and the plate (8) are in contact with the lubricating oil, and the plate (8) contacts the stepped portion on the upper side of the concave portion of the sleeve (5) in the axial direction and the radial direction. In such a contact portion, there is a gap at the intersection of the axial contact surface and the radial contact surface in assembly design. Air exists in this gap.

  In a dynamic pressure bearing, in order to remove the air inside the bearing, generally, before the lubricating oil is injected, the pressure inside the bearing is reduced to exclude the air inside the bearing. However, in this gap, the periphery is in contact with the axial direction and the radial direction, and the gap for excluding air is not sufficient. Therefore, air may remain in the gap even when the pressure is reduced. The remaining air may be replaced with lubricating oil that has entered the axial contact surface. As a result, the lubricating oil corresponding to the volume of the air decreases, which may affect the motor life. If the air enters the inside of the bearing, the rotational performance of the motor is seriously affected, and there is a possibility that the read / write of the recording disk placed on the motor is affected.

  The present invention provides a spindle motor that has improved the impact resistance and reliability while solving the above problems.

According to claim 1 of the present invention, a stationary member, a rotating member that is rotatable relative to the stationary member, a bearing surface of the stationary member, and the rotating member that faces the bearing surface in the radial direction Bearing surfaces, a lubricating fluid interposed between the two bearing surfaces, and a dynamic pressure generating groove provided on at least one of the two bearing surfaces, and rotatably supporting the rotating member with respect to the stationary member The bearing member is mounted in contact with the rotating member or the stationary member in the axial direction and the radial direction, and is opposed to the stationary member or a part of the rotating member by forming a seal gap in the radial direction. And an auxiliary member that forms a gas-liquid interface of the lubricating fluid that communicates with the hydrodynamic bearing portion;
In a spindle motor comprising:
Wherein a surface auxiliary member abuts axially on the rotary member or the stationary member, at least one of the face of the rotary member or the stationary member and corresponding said surface, the recess continuous in the radial direction Formed by opening an edge to the seal gap ,
The concave portion is disposed in a gap from the dynamic pressure bearing portion to the seal gap,
The recess is filled with the lubricating fluid .

  According to claim 2 of the present invention, according to claim 1, the recess is characterized in that the width of the recess expands outward in the radial direction.

  According to a third aspect of the present invention, according to any one of the first and second aspects, the concave portion is formed in a curved shape.

  According to a fourth aspect of the present invention, according to any one of the first to third aspects, the seal gap is formed in a taper shape that extends downward in the axial direction.

  According to claim 5 of the present invention, the seal gap is formed so as to be inclined in the radial direction toward the upper side in the axial direction.

  According to a sixth aspect of the present invention, there is provided a recording disk drive device equipped with the spindle motor according to any one of the first to fifth aspects.

  According to the first aspect of the present invention, since the concave portion is formed in at least one of the surfaces of the stationary member and the auxiliary member that are in contact with each other and the seal gap is opened, the lubricating fluid has the centrifugal force of the motor rotation. By flowing into the recess, the force for drawing the lubricating fluid in the vicinity of the seal gap is increased, so that the impact resistance of the seal gap can be improved.

  According to the second and third aspects of the present invention, since the width of the concave portion extends radially outward, the centrifugal force action in the concave portion is strengthened, and the impact resistance of the seal gap can be improved. Further, since the shape of the concave portion is curved, the lubricating fluid in the concave portion can be smoothly moved radially outward, so that the impact resistance of the seal gap can be improved.

  According to the fourth and fifth aspects of the present invention, the action of centrifugal force due to the rotation of the motor can be improved by inclining the seal gap to the taper structure or radially outward, and the force for drawing the lubricating fluid into the motor. Since it becomes stronger, the impact resistance of the seal gap can be improved.

  According to the sixth aspect of the present invention, by mounting the spindle motor of the present invention, it is possible to provide a recording disk drive device with high impact resistance, in which scattering of the lubricating fluid is suppressed.

  An embodiment of a spindle motor according to the present invention is shown in FIG. FIG. 1 is an axial sectional view. An enlarged view of part A in FIG. 1 is shown in FIG.

  First, the entire spindle motor will be described with reference to FIG.

  The sleeve 10 has a hollow cylindrical shape made of a sintered member, and radial bearing portions 11a and 11b are formed on the upper and lower axial sides of the inner peripheral surface of the cylindrical portion 11, respectively. Further, a substantially bottomed cylindrical housing 20 is in contact with the outer peripheral surface of the cylindrical portion 11. A part of the cylindrical portion of the housing 20 on the upper side in the axial direction has a tapered portion 21 that spreads outward in the radial direction toward the upper side in the axial direction. A thrust bearing portion 22 is formed on the upper end surface of the housing 20. Further, a projecting portion 61 having a hollow case 60 is fixed to the lower side in the axial direction of the cylindrical portion of the housing 20 so as to accommodate the housing 20 in a hollow state. The bottom portion 23 of the housing 20 is provided so as to accommodate the lower end surface 12 of the sleeve 10.

  A rotor hub 30, which is a rotating body, is inserted into the hollow portion of the sleeve 10 and is rotatably supported. The rotor hub 30 has a substantially bottomed cylindrical shape having a shaft portion 31 that protrudes from the center of the rotor hub 30 and is inserted into the sleeve 10. At the upper end of the cylindrical portion 32, a placement portion 32a for placing a recording disk is formed. Further, a part of the cylindrical part 32 is formed with an extension part 32b extending outward in the radial direction, and a part of the extension part 32b is formed with a protruding part 32c that protrudes downward in the axial direction. A bottom surface portion 33 is provided so as to connect the shaft portion 31 and the cylindrical portion 32.

  A substantially hollow cylindrical retaining member 40 is in contact with the inner peripheral surface of the cylindrical portion 32 of the rotor hub 30 so as to be opposed to the housing 20 via a minute gap in the radial direction. The axially upper portion 41 of the retainer 40 is formed with a tapered portion 41a that inclines radially outward as it goes upward in the axial direction. Further, in the axially lower side portion 42 of the retainer 40, the inner diameter of the hollow portion is increased, and a surface connecting the axially upper side portion 41 and the axially lower side portion 42 is formed at the boundary 43. ing.

  Further, the lubricating fluid is filled so as to fill the space between the thrust bearing portion 22 of the housing 20 and the radial bearing portions 11a and 11b without any gap. At this time, a gas-liquid interface 70 between the lubricating fluid and the outside air is formed between the tapered portion 21 of the housing 20 and the tapered portion 41 a of the retaining member 40.

  The rotor magnet 50 is fixed to the outer peripheral surface of the cylindrical portion 32 of the rotor hub 30, the portion surrounded by the extended portion 32b, and the protruding portion 32c so as to contact the outer peripheral surface of the cylindrical portion 32 and the protruding portion 32c. A stator (not shown) is fixedly disposed on the case 60 so as to face the rotor magnet 50 via a minute gap in the radial direction. When the stator is energized, a magnetic field is generated, and a rotational force is generated by the interaction between the stator magnetic field and the rotor magnet 50.

  Next, the detail of A part is demonstrated with reference to FIG.

  Referring to FIG. 2, the stopper 40 is fixed while being in contact with the axial contact surface 32 d and the radial contact surface 32 e of the cylindrical portion 32 of the rotor hub 30. Also, an intersection surface 32f between the axial contact surface 32d and the radial contact surface 32e has an R-surface shape, and a chamfered portion 43 is formed at a location facing the intersection portion 32f of the retaining member 40. Yes. This is performed in order to improve the accuracy of attaching the retainer 40 to the rotor hub 30. As a result, a gap 80 is formed between the axial contact surface 32d, the radial contact surface 32e and the intersecting portion 32f of the rotor hub 30 and the chamfered portion 43 of the retaining member 40. In addition, a recess 45 that connects the inner peripheral edge and the outer peripheral edge of the stopper 40 is formed in a part of the upper end surface 44 of the stopper 40 that contacts the axial contact surface 32d of the rotor hub 30.

  Since the recess 45 is formed, the gap 80 can communicate with the outside of the motor. Therefore, the air existing in the gap 80 can be smoothly removed when the pressure is reduced before the lubricating fluid is injected. Further, since the lubricating fluid can be filled more than the space between the recess 45 and the axial contact surface 32d of the rotor hub 30, the life of the motor can be extended. The lubricating fluid in the space between the recess 45 and the axial contact surface 32d of the rotor hub 30 is subjected to a radially outward force due to the centrifugal force generated by the rotation of the motor, strengthening the sealing force of the gas-liquid interface 70, and impact resistance. The improvement is realized.

  The minute gap formed by the taper portion 21 of the housing 20 and the taper portion 41a of the retainer 40 has a structure that inclines radially outward as it goes upward in the axial direction. With this structure, the gas-liquid interface 70 can be further improved in impact resistance because a force acts on the upper side in the axial direction due to the centrifugal force caused by the rotation.

  A protrusion 25 is formed between the thrust bearing surface 22 of the housing 20 and the tapered portion 21 so as to protrude outward in the radial direction. The position of the protrusion 25 is arranged so as to intersect the upper end surface 44 of the retaining member 40 in the axial direction upper side and in the radial direction. As a result, even if an impact is applied and the rotor hub 30 is lifted, the upper end surface 44 of the retainer 40 and the protrusion 25 of the housing 20 come into contact with each other, thereby restricting the axial position and preventing the rotor hub 30 from coming off. be able to.

  Next, the recess 45 formed on the upper end surface 44 of the retaining member 40 will be described with reference to FIGS. 3 to 10 are views of the retainer 40 as viewed from the upper end surface side. The arrows in FIGS. 4 to 10 indicate the direction of rotation.

  Referring to FIG. 3, four recesses 45 are formed at equal intervals in the circumferential direction and parallel to the radial direction. The shape of the recess 45 is such that the wall 46a in the same direction with respect to the rotation direction as shown in FIG. 4 is inclined to the same side as the rotation direction, and the wall 46b in a direction different from the rotation direction as shown in FIG. By inclining to the side different from the rotation direction, the walls 46a and 46b guide the lubricating fluid, and the flow of the lubricating fluid to the outside in the radial direction by centrifugal force can be performed more smoothly. Further, inclining these walls 46a and 46b is to increase the width of the concave portion 46 with respect to the outer side in the radial direction, so that a larger amount of lubricating fluid can be moved outward in the radial direction. Similar effects can be obtained by inclining both sides of the recess walls 46a and 46b as shown in FIG.

  Moreover, you may curve the walls 46a and 46b of the recessed part 46 like FIG. 7 thru | or FIG. 7 to 10 show diagrams corresponding to FIGS. 3 to 6 in order. By bending the walls 46a and 46b of the recess 46, the lubricating fluid can be moved more smoothly outward in the radial direction. As a result, since the centrifugal force action of the lubricating fluid is strengthened, the sealing force of the gas-liquid interface 70 is further strengthened, and the impact resistance can be further improved. This bending direction can obtain the same effect with respect to any of the rotational directions.

  Finally, an embodiment of a recording disk drive apparatus equipped with the spindle motor of the present invention will be described with reference to FIG.

  Referring to FIG. 11, the recording disk drive device 100 includes a rectangular housing 110 (corresponding to the spindle motor case 60 of the present invention), and the interior of the housing 110 is clean with extremely little dust and dirt. A spindle motor 130 on which a disk-like hard disk 120 for recording information is mounted is disposed therein.

  In addition, a head moving mechanism 140 that reads and writes information from and to the hard disk 120 is disposed inside the housing 110. The head moving mechanism 140 includes a magnetic head 141 that reads and writes information on the hard disk 120, and the magnetic head 141. The supporting arm 142, the magnetic head 141, and the arm 142 are configured by an actuator unit 143 that moves the arm 142 to a required position on the hard disk 120.

  By applying the spindle motor of the present invention as the spindle motor 130 of such a recording disk drive device 100, the recording disk drive device 100 can be reduced in size and thickness while ensuring a sufficient function, and also reliable. In addition, a highly durable recording disk drive device can be provided.

  While the spindle motor and the recording disk driving device including the spindle motor according to the present invention have been described above, the present invention is not limited to such an embodiment, and various modifications and corrections can be made without departing from the present invention. It is.

  For example, FIGS. 12 and 13 are diagrams showing another embodiment of the embodiment according to the present invention. 12B is an enlarged view of part B of FIG. 12B, and FIG. 13B is an enlarged view of part C of FIG. 13B. Further, since the structure of the spindle motor is symmetric with respect to the axis, the half sectional view taken from the axis center is shown.

  Referring to FIG. 12 b), a tapered bush 200 is attached to the rotor hub 210 instead of the stopper 40, and a concave portion 202 is formed on the upper end surface 201 of the tapered bush 200, so that the gas-liquid interface 220 is formed. A similar effect can be obtained.

  Referring to FIG. 13 b, a capillary seal 300 is attached to the rotor hub 310 instead of the stopper 40, and a recess 302 is formed in the lower end surface 301 of the capillary seal 300, so that the gas-liquid interface 320 is formed. A similar effect can be obtained.

  The recesses 202 and 302 may be formed on the rotor hubs 210 and 310 side.

  Here, the spindle motor of the present invention is an inner rotor type, but is not limited to this, and may be an outer rotor type as shown in FIG. 12 a) and FIG. 13 a). Further, the present invention can also be applied to a spindle motor with a fixed shaft as shown in FIG.

  Further, in the spindle motor of the present invention, the rotor hub 30 and the shaft portion 31 are integrated. However, the present invention is not limited to this, and the spindle motor may be separate as shown in FIG. 12 a) and FIG. 13 a). In the spindle motor of the present invention, the sleeve 10 and the housing 20 are separate, but the present invention is not limited to this, and may be integrated.

  Further, for example, in the present invention, the upper end surface 44 other than the recess 46 of the retainer 40 is in contact with the axial contact surface 32d of the rotor hub 30, but the present invention is not limited to this, and the recess 46 has a protruding shape, The concave portion 46 may be in contact with the axial contact surface 32 d of the rotor hub 30. Moreover, although the number of the recessed parts 46 was four in this invention, it should just be at least one, without being limited to this. In the present invention, the recess 46 is formed on the upper end surface 44 of the retaining member 40. However, the recess 46 only needs to be formed on the coupling surface between the rotor hub 30 and the retaining member 40 and communicate with the gap 80. You may form in the direction contact surface 32d side.

1 is an axial sectional view showing an embodiment of a spindle motor according to the present invention. It is the figure which showed the relationship between the rotor hub which showed the principal part of this invention, retaining, and a housing (enlarged view of the A section of FIG. 1). It is the top view which showed one form of the Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is the top view which showed the other Example of the recessed part formed in the upper end surface of a thrust plate. It is sectional drawing which showed one form of the Example of the recording disk drive device of this invention. a) is a half sectional view showing an embodiment of another embodiment of the spindle motor according to the present invention, and b) is an enlarged view of a portion B of a). a) is a half sectional view showing one embodiment of another embodiment of the spindle motor according to the present invention, and b) is an enlarged view of a portion C of a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sleeve 11a, 11b Radial bearing part 20 Housing 21 Tapered part 22 Thrust bearing part 23 Bottom face 30, 210, 310 Rotor hub 31 Shaft part 32 Cylindrical part 32a Mounting part 32b Extension part 32c Protrusion part 32d Axial contact surface 32e Radial direction Contact surface 32f Crossing portion 33 Bottom surface portion 40 Retaining prevention 41 Axial contact surface 41a Taper portion 42 Radial contact surface 43 Chamfered portion 44 Upper end surface 45, 202, 302 Recessed portion 46a, 46b Wall 50 Rotor magnet 60 Case 70 , 220, 320 Gas-liquid interface
80 Gap 100 Recording disk drive
200 Taper bush 300 Capillary seal

Claims (6)

A stationary member;
A rotating member that is rotatable relative to the stationary member;
The bearing surface of the stationary member, the bearing surface of the rotating member that faces the bearing surface in the radial direction, the lubricating fluid interposed between the bearing surfaces, and the generation of dynamic pressure provided on at least one of the bearing surfaces A hydrodynamic bearing configured by a groove and rotatably supporting the rotating member with respect to the stationary member;
The dynamic pressure bearing portion is attached to the rotating member or the stationary member so as to be in contact with each other in the axial direction and the radial direction, and is opposed to the stationary member or a part of the rotating member by forming a seal gap in the radial direction. An auxiliary member that forms a gas-liquid interface of the lubricating fluid leading to
In a spindle motor comprising:
At least one of the surface where the auxiliary member abuts against the rotating member or the stationary member in the axial direction and the surface of the rotating member or the stationary member corresponding to the surface has a concave portion that is continuous in the radial direction. Formed by opening an edge to the seal gap ,
The concave portion is disposed in a gap from the dynamic pressure bearing portion to the seal gap,
The spindle motor according to claim 1, wherein the recess is filled with the lubricating fluid .   The spindle motor according to claim 1, wherein the concave portion has a width of the concave portion that extends outward in the radial direction.   The spindle motor according to claim 1, wherein the concave portion is formed in a curved shape.   The spindle motor according to any one of claims 1 to 3, wherein the seal gap is formed in a taper shape that extends downward in the axial direction.   5. The spindle motor according to claim 1, wherein the seal gap is formed so as to be inclined in the radial direction and toward the upper side in the axial direction.   6. A recording disk drive apparatus comprising the spindle motor according to claim 1.

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