JP4043849B2 - Recording disk drive motor - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a recording disk drive motor that includes a fluid dynamic pressure bearing and drives a recording disk such as a hard disk.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a recording disk drive motor constituting a hard disk drive (HDD) mainly used in a personal computer or the like has a fluid motion that can obtain high-speed and high-precision rotation compared to a conventional ball bearing. Bearings using pressure have begun to spread.
[0003]
As a recording disk driving motor having a conventional fluid dynamic pressure, for example, a structure shown in FIG. 5 is known. In this recording disk drive motor, a cylindrical portion 102a is formed at the center of a base plate 102, which is a fixing member, and a stator 104 is fixedly held on the outer periphery of the cylindrical portion 102a. A sleeve 106 is fixedly held on the inner peripheral portion of the cylindrical portion 102a.
[0004]
The sleeve 106 and the shaft 108, which is a rotating body, face each other in the radial direction via the first and second fluid dynamic pressure radial bearing portions 126 and 128. Further, the upper end surface 106 a of the sleeve 106 and the lower surface of the upper wall portion 112 a of the rotor hub 112 that are fitted and fixed to the shaft 108 are opposed to each other in the axial direction via the fluid dynamic pressure thrust bearing portion 114.
[0005]
A peripheral wall 112b that hangs down in the axial direction is formed on the outer peripheral portion of the rotor hub 112, and a cylindrical rotor magnet 116 that is opposed to the stator 104 in the radial direction is fixed to the inner peripheral surface of the peripheral wall 112b. By applying a current to the coil wound around the stator 104, electromagnetic interaction occurs between the stator 104 and the rotor magnet 116, and the rotor hub 112 and the shaft 108 rotate integrally.
[0006]
A flange portion 112c is formed on the peripheral wall portion 112b of the rotor hub 112, and one or a plurality of recording disks 118 are fixed using a spacer 120 made of an annular material, a clamp member 122, and a fastening means 124. That is, when the screw portion of the fastening means 124 is screwed into the screw hole 108 a provided in the shaft 108, the flange portion of the fastening means 124 comes into contact with the base portion 122 a of the clamp member 122, and the base portion 122 a is axially inward ( The pressing force of the fastening means 124 is applied from the base portion 122a of the clamp member 122 to the action portion 122b arranged radially outward from the upper end portion 112a of the rotor hub 112. The action portion 122b narrows and holds the recording disk 118 and the spacer 120 between the upper surface of the flange portion 112c provided on the peripheral wall portion 112b of the rotor hub 112.
[0007]
[Problems to be solved by the invention]
However, in the recording disk drive motor using the center clamp type configuration in which the clamp member 122 is fixed by screwing the screw portion of the fastening means 124 into the screw hole 108a provided in the shaft in this way, the recording disk 118 is mounted. Sometimes, the axial pressing force applied from the fastening means 124 to the clamp member 122 is transmitted to the upper wall portion 112a of the rotor hub 112 via the clamp member 122, and the upper wall portion 112a of the rotor hub 112 may be greatly deformed. .
[0008]
When such deformation occurs, the upper wall portion 112a of the rotor hub bends, the axial dimension of the gap in the fluid dynamic pressure thrust bearing portion 114 becomes uneven, and a stable shaft support force is obtained in the fluid dynamic pressure thrust bearing portion 114. In addition to the deterioration of the rotational speed of the motor, the lower surface of the upper wall portion 112a of the rotor hub 112 constituting the fluid dynamic pressure thrust bearing portion 114 and the upper end surface 106a of the sleeve are brought into contact with each other. There is a concern that troubles such as wear, damage, or seizure may occur, and the durability and reliability of the motor may be reduced.
[0009]
The present invention has been made in view of the above problems, and its purpose is to avoid the influence on the bearing portion due to the pressing force of the clamp member acting on the rotor hub, and to keep the gap of the fluid dynamic pressure thrust bearing portion constant. Another object of the present invention is to provide a recording disk drive motor that can maintain high-precision rotation and has high durability and reliability.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a recording disk drive motor according to claim 1 of the present invention includes a substantially disk-shaped upper wall portion and a recording disk that hangs down from the outer peripheral portion of the upper wall portion. A rotor hub constituted by a peripheral wall portion to be held;SaidA shaft that rotates integrally with the rotor hub;Inner circumferenceThe base ofSaidWhile being pressed and held by a fastening means screwed into a screw hole provided in the axial direction of the shaft,Outer peripheral sideIs the recording diskAnd the recording diskVia a clamp member that elastically presses and a fluid dynamic bearingSaidA sleeve for supporting the shaft,SaidRotor hubofThe lower surface of the upper wall andSaidA fluid dynamic pressure thrust bearing is provided between the upper end surface of the sleeve.ThisIn the recording disk drive motor
The clamp member further includes an annular intermediate portion that connects the base and the action portion,
A gap is formed between the annular intermediate portion and the rotor hub facing the intermediate portion, and between the upper wall portion and the base portion, respectively.
  SaidThe fastening means isSaidClamp member isSaidRegarding motor axis directionSaidWith a gapSaidThe amount of tightening in the axial direction is regulated so that it faces the rotor hub.,
  The axial gap dimension between the annular intermediate portion and the rotor hub facing the annular intermediate portion is larger than the axial gap dimension between the upper wall portion and the base portion.It is characterized by that.
[0011]
In the recording disk drive motor according to claim 2 of the present invention, the shaft is fixedly fitted to the rotor hub base portion, and the fitting portion has a small diameter, so that the axial fitting depth of the rotor hub is reduced. It is characterized by regulation.
[0012]
In the recording disk drive motor according to the third aspect of the present invention, the base of the clamp member is provided with a protrusion that hangs inward in the axial direction from the lower end surface of the base and contacts the upper end surface of the shaft. The portion is sandwiched and fixed in the axial direction by the fastening means and the upper end surface of the shaft, whereby the amount of fastening in the axial direction of the fastening means is restricted.
[0013]
In the recording disk drive motor according to claim 4 of the present invention, it extends axially outward (upward in the figure) from the upper end surface of the upper wall portion of the rotor hub fitted and fixed to the shaft. A protruding part is provided, and the protruding part is brought into contact with the fastening means in the axial direction, whereby the tightening amount of the fastening means in the axial direction is restricted.
[0014]
In the recording disk drive motor according to claim 5 of the present invention, from the fitting portion between the rotor hub and the shaft to the outer peripheral portion of the screw hole provided in the shaft at the base side end of the upper wall portion of the rotor hub. A projecting portion extending inward in the radial direction is provided, and the projecting portion is sandwiched and fixed in the axial direction by the fastening means and the upper end portion of the shaft, whereby the fastening means is moved inward in the axial direction. The tightening amount is regulated.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a recording disk driving motor according to the present invention will be described below with reference to the drawings.
[0016]
First embodiment
In FIG. 1, the recording disk drive motor according to the embodiment of the present invention includes a rotor hub 12, a shaft 8 that rotates integrally with the rotor hub 12, a clamp member 22 that is pressed and held by fastening means 24, and the shaft 8. And a sleeve 6 that rotatably supports the shaft 8 via first and second dynamic pressure radial bearing portions 26 and 28, and a base plate 2 integrally formed with a cylindrical portion 2a that fixes and holds the sleeve 6. ing.
[0017]
The rotor hub 12 is provided with a substantially disk-shaped upper wall portion 12a and a cylindrical peripheral wall portion 12b that hangs from the outer peripheral portion of the upper wall portion 12a and holds the recording disk 18 on the outer peripheral portion.
[0018]
    The clamp member 22 includes the clamp member 22Inner circumferenceA base portion 22a located on the outer periphery of the clamp member 22 and an action portion 22b located on the outer peripheral side of the clamp member 22.An annular intermediate portion connecting the base portion 22a and the action portion 22b;Is provided. When the male thread portion of the fastening means 24 is screwed into the screw hole 8 a provided in the axial direction of the shaft 8, the base portion 22 a is pushed down by the large diameter portion of the fastening means 24, so that the action portion 22 b becomes the outer periphery of the rotor hub 12. The recording disk 18 placed on the unit is elastically pressed.
[0019]
The stator 4 is fitted and fixed to the outer peripheral portion of the cylindrical portion 2a of the base plate 2, and the sleeve 6 is fitted and fixed to the inner peripheral portion. The stator 4 is opposed to the rotor magnet 16 fixedly held on the inner peripheral surface of the peripheral wall portion 12b of the outer peripheral portion of the rotor hub 12 with a gap in the axial direction.
[0020]
A shaft 8 is inserted into the inner periphery of the sleeve 6, and the inner peripheral surface of the sleeve 6 and the outer peripheral surface of the shaft 8 are opposed to each other in the radial direction through a gap, and the gap is filled with lubricating oil. First and second fluid dynamic pressure radial bearing portions 26 and 28 that are spaced apart in the axial direction are formed.
[0021]
Of the first and second fluid dynamic pressure radial bearing portions 26, 28, at least one of the inner peripheral surface of the sleeve 6 and the outer peripheral surface of the shaft 8 is included in the first fluid dynamic pressure radial bearing portion 26 positioned at the upper part in the axial direction. Is formed with a herringbone groove having an unbalanced shape in the axial direction, and when the rotor hub 12 rotates, the lubricating oil moves upward in the axial direction (the inner end side of the base portion of the upper wall portion 12a of the rotor hub 12). A moving pressure towards is induced.
[0022]
Further, the second fluid dynamic pressure radial bearing portion 28 located in the lower portion in the axial direction has a herringbone groove having a shape balanced in the axial direction on at least one of the inner peripheral surface of the sleeve 6 and the outer peripheral surface of the shaft 8. When the rotor hub 12 rotates, a moving pressure of the lubricating oil from both ends of the second fluid dynamic pressure radial bearing portion toward the center portion is induced.
[0023]
The upper end surface of the sleeve 6 and the lower surface of the upper wall portion of the rotor hub 12 face each other in the axial direction through a gap, and lubricating oil is held in the gap. At least one surface of the upper end surface 6a of the sleeve 6 and the lower surface 12a1 of the upper wall portion of the rotor hub 12 is of a pump-in type so that the lubricating oil is induced by a moving pressure directed radially inward (on the shaft 8 side). A spiral groove is formed to constitute the fluid dynamic pressure thrust bearing portion 14.
[0024]
The sleeve 6 has a first series of through-holes that pass through in the radial direction of the sleeve 6 so as to open at a substantially central portion in the axial direction of the gap formed between the outer peripheral surface of the shaft 8 and the inner peripheral surface of the sleeve 6. 6b is formed, and an annular recess 8b composed of a pair of inclined surfaces each inclined so as to become deeper toward the center in the axial direction is formed at a position facing the first through hole 6b on the outer peripheral surface of the shaft 8. Has been. The radial dimension of the gap between the outer peripheral surface of the shaft 8 and the inner peripheral surface of the sleeve 6 is maximum at the substantially central portion in the axial direction of the annular recess 8b, and in other words toward the both ends, The pressure gradually decreases toward the second fluid dynamic pressure radial bearing portions 26 and 28. In addition, a second communication hole 6 c is also formed in the lower end portion of the sleeve 6.
[0025]
An axial groove 6d extending from the upper end to the lower end of the sleeve 6 through the opening of the first continuous hole 6b on the outer peripheral surface of the sleeve 6 and the opening of the second communication hole 6c at the lower end of the sleeve 6 is provided. Thus, the first through hole 6b and the second communication hole 6c communicate with the outside air by the axial groove 6d.
[0026]
Between the annular recess 8b and the inner peripheral surface of the sleeve 6, there is formed a gas intervening portion 7 in which air that has entered through the axial groove 6d of the sleeve 6 and the first through hole 6b is interposed. 7, the lubricating oil held by the first and second fluid dynamic pressure radial bearing portions 26 and 28 is separated in the axial direction.
[0027]
The lubricating oil is continuously held in the gap from the first fluid dynamic pressure radial bearing portion 26 to the fluid dynamic pressure thrust bearing portion 14. In the first fluid dynamic pressure radial bearing portion 26, the lubricating oil is induced to move upward in the axial direction due to the unbalanced herringbone groove. Pressure increases. In addition, the lubricating oil is replenished to the first fluid dynamic pressure radial bearing portion 26 in the fluid dynamic pressure thrust bearing portion 14 because a moving pressure is induced radially inward due to the pump-in type spiral groove. Acts to be.
[0028]
In other words, the first fluid dynamic pressure radial bearing portion 26 and the fluid dynamic pressure thrust bearing portion 14 cooperate to act in a radial direction with respect to the rotor hub 12 and in a direction that rises with respect to the base plate 2. Axial support force in the axial direction is applied.
[0029]
An annular retaining ring 9 is fitted and fixed to the small diameter portion of the lower end portion of the shaft 8 (the end portion opposite to the side end portion of the base portion 12a to which the rotor hub 12 is fitted). The ring 9 enters an annular notch formed at the lower end on the inner periphery of the sleeve 6. A thrust yoke 11 formed of an annular magnetic material is fixed to the inner bottom portion of the base plate 2 so as to face the rotor magnet 16 in the axial direction.
[0030]
The retaining ring 9 prevents the shaft 8 from coming off the sleeve. The thrust yoke 11 applies a magnetic bias to the axially lower side (base plate 2 side) so as to balance the floating force of the rotor hub 12 and the shaft 8 which are rotating members generated in the fluid dynamic pressure thrust bearing portion 14.
[0031]
At the upper end portion of the outer peripheral surface of the sleeve 6, an annular notch 6 e having a substantially L-shaped cross section that is inclined so that the axial wall becomes deeper downward is provided. From the lower surface of the upper wall portion 12a of the rotor hub 12, a circumferential projection 12d that is loosely fitted in the notched portion 6e is suspended.
[0032]
On the outer peripheral surface of the notch 6e that faces the inner peripheral surface of the circumferential protrusion 12d in the radial direction, the gap dimension in the radial direction of the gap defined between the two gradually increases in a taper direction downward in the axial direction. At the radially outer end of the fluid dynamic pressure thrust bearing portion 14, the inner peripheral surface of the circumferential protrusion 12d and the outer peripheral surface of the notch 6e of the sleeve cooperate to form a tapered seal portion 10. The lubricating oil held in the fluid dynamic pressure thrust bearing portion 14 is held in the tapered seal portion 10 by forming a meniscus at the interface between the lubricating oil and air, and balancing the surface tension of the lubricating oil and the external air pressure. Has been.
[0033]
      A clamp member 22 is disposed on the upper surface of the rotor hub 12 so as to cover the rotor hub 12. The clamp member 22 is made of a disc-shaped elastic spring member formed of, for example, stainless steel,Inner circumferenceThe base 22a ofOuter peripheral sideAction part 22b arranged inAn annular intermediate portion connecting the base portion 22a and the action portion 22b;Is provided.
[0034]
The base 22a of the clamp member 22 is pushed down by the lower surface of the large-diameter portion of the fastening means 24 when the fastening means 24 is screwed into a screw hole 8a provided at the upper end in the axial direction of the shaft 8 (on the side end face side of the rotor hub 12). It is done.
[0035]
The recording disk 18 is fitted and laminated on the outer periphery of the rotor hub 12 via the spacer 20. The lowermost recording disk 18 is placed on the flange 12c of the rotor hub 12, and the action portion 22b of the clamp member 22 presses the uppermost recording disk 18 to fix and hold the recording disk.
[0036]
That is, when the base 22 a of the clamp member 22 is pressed by the fastening means 24, the pressing force acting downward in the axial direction of the fastening means 24 is applied to the base 22 a of the clamp member 22 from the lower surface of the large diameter portion of the fastening means 24. When transmitted to the end face, the clamp member 22 is pushed downward in the axial direction, and the pressing force by the fastening means 24 is transmitted from the base portion 22a of the clamp member 22 to the action portion 22b, and the action portion 22b causes the recording disk 18 and the spacer 20 to move. Then, it is sandwiched and fixed in the axial direction between the upper surface of the flange 12c provided on the peripheral wall 12b of the rotor hub 12.
[0037]
Next, the configuration and principle of the present invention will be described with reference to FIG.
[0038]
FIG. 2 is a partially enlarged cross-sectional view showing a configuration for restricting the amount of tightening of the fastening means 24 downward in the axial direction in the embodiment of FIG. The fastening means 24 includes a large-diameter portion 24a, a medium-diameter portion 24b positioned below the large-diameter portion 24a in the axial direction, and a small-diameter portion 24c positioned below the medium-diameter portion 24b in the axial direction.
[0039]
An annular projecting portion 12 a 1 is provided at the inner end of the base portion of the upper wall portion 12 a of the rotor hub 12. The projecting portion 12 a 1 extends from the inner end of the base portion of the upper wall portion 12 a of the rotor hub 12 to the inner diameter side, the lower surface of the projecting portion 12 a 1 is in contact with the upper end surface in the axial direction of the shaft 8, and the upper surface is inside the fastening member 24. It is in contact with the lower surface of the diameter portion and is sandwiched and fixed between both surfaces.
[0040]
    Here, the protrusion 12a1 of the rotor hub 12 regulates the amount of fastening of the fastening means 24 downward in the axial direction, and is between the lower end surface of the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12., And an annular intermediate portion that connects the base portion 22a and the action portion 22b of the clamp member 22 and the rotor hub facing the annular intermediate portion, respectively.Axial directionBetweenThe axial thickness dimension is determined so that a gap is generated.
[0041]
That is, when the fastening means 24 is screwed into the screw hole 8a of the shaft 8, the lower end surface of the large diameter portion 24a of the fastening means 24 and the upper end face of the base portion 22a of the clamp member 22 are in contact with each other in the axial direction. The small diameter portion 24c of 24 and the side end surface of the protruding portion 12a1 of the upper wall portion 12a of the rotor hub 12 face each other with a gap in the radial direction.
[0042]
At this time, the clamp member 22 is pushed downward in the axial direction (upper end surface side of the rotor hub 12), but the fastening means 24 is allowed to move against the screw hole 8a of the shaft 8 by the protrusion 12a1 of the upper wall portion 12a of the rotor hub 12. Since the amount to be tightened downward in the axial direction is restricted, between the lower end surface of the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12And between the annular intermediate portion connecting the base portion 22a and the action portion 22b of the clamp member 22 and the rotor hub,Opposite the gap in the axial direction.
[0043]
Due to this gap, the pressing force applied from the fastening means 24 to the clamp member 22 is transmitted to the upper wall portion 12a of the rotor hub 12, and deformation of the upper wall portion 12a of the rotor hub 12 is avoided.
[0044]
Further, the projecting portion 12a1 also regulates the position in the axial direction of the rotor hub 12 by having the lower surface thereof in contact with the upper end surface of the shaft.
[0045]
The axial thickness dimension of the protruding portion 12a1 of the upper wall portion 12a of the rotor hub 12 is between the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12.And between the annular intermediate portion connecting the base portion 22a and the action portion 22b of the clamp member 22 and the rotor hub facing the annular intermediate portion.There is a gap in theThe axial gap dimension between the annular intermediate portion and the rotor hub facing the annular intermediate portion is larger than the axial gap dimension between the upper wall portion 12a and the base portion 22a.,MoreThe action portion 22b of the clamp member 22 is set so as to balance the force for holding and fixing the recording disk 18 with the flange portion 12c of the peripheral wall portion 12b of the rotor hub 12. Moreover, you may form the protrusion part 12a1 by the some protrusion piece arrange | positioned in the circumferential direction at intervals instead of making it cyclic | annular. In this case, it is necessary to balance the size and arrangement of the protruding pieces so that the rotor hub 12 can obtain a stable rotational force. Further, since the protruding portion 12a1 only needs to regulate the axial position of the fastening means 24 and the rotor hub 12 as described above, the radially inner tip portion comes into contact with the outer periphery of the small diameter portion 24c of the fastening means 24. There is no need.
[0046]
Second embodiment
FIG. 3 is a partially enlarged cross-sectional view showing another embodiment for restricting the amount of fastening of the fastening means 24 in the axial direction downward. The structure of the recording disk drive motor is substantially the same as in the first embodiment, but in this embodiment, the base inner end of the upper wall portion 12a of the rotor hub 12 is externally fixed to the small diameter portion 8c of the shaft 8. Then, the position of the rotor hub 12 in the axial direction is regulated by the step portion at the lower end of the small diameter portion of the shaft 8.
[0047]
Further, the fastening means 24 of the present embodiment has a large diameter portion 24a of the fastening means 24 and a small diameter portion 24c positioned above the large diameter portion 24a in the axial direction.
[0048]
An annular protrusion 22a1 is provided at the lower end of the base 22a of the clamp member 22.
[0049]
The projecting portion 22a1 contacts the upper end of the shaft 8, regulates the amount of fastening of the fastening means 24 in the axial direction downward, and faces each other in the axial direction of the base portion 22a of the clamp member 22 and the upper wall portion 12a of the rotor hub 12. PartAnd an annular intermediate portion connecting the base portion 22a and the action portion 22b of the clamp member 22 and a portion facing the rotor hub 12 in the axial direction.A gap is formed in the gap.
[0050]
That is, when the fastening means 24 is screwed into the screw hole 8a provided in the shaft 8, the lower end surface of the large diameter portion 24a of the fastening means 24 and the upper end surface of the base portion 22a of the clamp member 22 are in contact with each other in the axial direction. The small diameter portion 24c of the fastening means 24 and the inner peripheral surface of the protruding portion 22a1 of the base portion 22a of the clamp member 22 are opposed to each other via a gap in the radial direction.
[0051]
At this time, the clamp member 22 is pushed down in the axial direction (upper end surface side of the rotor hub 12), but the fastening means 24 is axially moved with respect to the screw hole 8 a of the shaft 8 by the protrusion 22 a 1 of the base portion 22 a of the clamp member 22. Since the downward tightening amount is restricted, the lower end surface of the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12 face each other with a gap in the axial direction.Further, there is a gap between the annular intermediate portion that connects the base portion 22a and the action portion 22b of the clamp member 22 and the rotor hub 12 facing the annular intermediate portion.
[0052]
Due to this gap, the pressing force applied from the fastening means 24 to the clamp member 22 is transmitted to the upper wall portion 12a of the rotor hub 12, and deformation of the upper wall portion 12a of the rotor hub 12 is avoided.
[0053]
The axial dimension of the projecting portion 22a1 of the clamp member 22 projecting from the lower end surface of the base portion 22 has a gap between the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12, The action portion 22b of the clamp member 22 is set to hold and fix the recording disk 18 between the flange portion 12c of the peripheral wall portion 12b of the rotor hub 12. Moreover, you may form the protrusion part 22a1 of the clamp member 22 by the some protrusion piece arrange | positioned in the circumferential direction at intervals instead of making it cyclic | annular. In this case, it is necessary to balance the rotor hub 12 so that a stable rotational force can be obtained.
[0054]
Third embodiment
FIG. 4 is a partially enlarged cross-sectional view showing still another embodiment for restricting the amount of fastening of the fastening means 24 in the axial direction downward. The structure of the recording disk drive motor is almost the same as that of the first embodiment. In this embodiment, the base inner end of the upper wall portion 12a of the rotor hub 12 is the same as that of the second embodiment. The axial position of the rotor hub 12 is regulated by the stepped portion at the lower end of the small diameter portion of the shaft 8 that is fitted and fixed to the small diameter portion 8c.
[0055]
The fastening means 24 includes a large-diameter portion 24a at the outermost diameter portion of the fastening means 24, a medium-diameter portion 24b positioned axially downward (on the upper end surface side of the shaft 8) with respect to the large-diameter portion 24a, and a medium-diameter portion. And a small diameter portion 24c positioned below the axial direction with respect to 24b.
[0056]
A cylindrical projecting portion 8 d extending upward in the axial direction is provided at the upper end portion of the shaft 8.
[0057]
      The protruding portion 8d of the shaft 8 restricts the amount of fastening of the fastening means 24 in the axial direction downward, and the portions facing each other in the axial direction between the base portion 22a of the clamp member 22 and the upper wall portion 12a of the rotor hub 12, And an annular intermediate portion that connects the base portion 22a and the action portion 22b of the clamp member 22 and a portion facing each other in the axial direction of the rotor hub 12,A gap is generated.
[0058]
That is, when the fastening means 24 is screwed into the screw hole 8a provided in the shaft 8, the lower end surface of the intermediate diameter portion 24b of the fastening means 24 and the upper end face of the protruding portion 8d of the shaft 8 are in contact with each other in the axial direction. .
[0059]
    At this time, the clamp member 22 is pushed downward in the axial direction (upper end surface side of the rotor hub 12), but the fastening means 24 is tightened downward in the axial direction with respect to the screw hole 8a of the shaft 8 by the protruding portion 8d of the shaft 8. Since the amount is regulated, the lower end surface of the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12 face each other with a gap in the axial direction.And the annular intermediate portion for connecting the base portion 22a and the action portion 22b of the clamp member 22 and the rotor hub 12 to each other.They are opposed to each other via a gap in the axial direction.
[0060]
Due to this gap, the pressing force applied from the fastening means 24 to the clamp member 22 is transmitted to the upper wall portion 12a of the rotor hub 12, and deformation of the upper wall portion 12a of the rotor hub 12 is avoided.
[0061]
It should be noted that the axial dimension of the protruding portion 8d extending upward in the axial direction of the upper end surface of the shaft 8 is between the base portion 22a of the clamp member 22 and the upper end surface of the upper wall portion 12a of the rotor hub 12.And between the annular intermediate portion connecting the base portion 22a and the action portion 22b of the clamp member 22 and the rotor hub facing the annular intermediate portion.A gap is interposed, and the action portion 22b of the clamp member 22 is set to balance the force for holding and fixing the recording disk 18 between the flange portion 12c of the peripheral wall portion 12b of the rotor hub 12.
[0062]
The embodiments according to the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made.
[0063]
For example, in this embodiment, lubricating oil is used as the fluid of the fluid dynamic pressure bearing. However, the present invention can also be applied to a motor using a so-called air dynamic pressure bearing using air as a fluid.
[0064]
【The invention's effect】
In the recording disk drive motor according to the first aspect of the present invention, the amount of tightening of the fastening means in the axially downward direction with respect to the screw hole provided in the shaft is restricted. Between the top edge of the wallAnd between the annular intermediate portion that connects the base portion 22a and the action portion 22b of the clamp member and the rotor hub facing the annular intermediate portion.A gap is generated, and the upper wall portion of the rotor hub is prevented from being deformed by the axially downward pressing force applied from the fastening means to the clamp member, and the lower surface of the upper wall portion of the rotor hub and the upper end surface of the sleeve are prevented from being deformed. The gap size of the gap in the fluid dynamic pressure thrust bearing part interposed therebetween is kept uniform, and the dynamic pressure induced by the pumping of the spiral groove is stabilized in the fluid dynamic pressure thrust bearing part. The shaft support in the pressure thrust bearing can be stabilized. Therefore, a stable shaft support force can be obtained and a high rotational support force can be maintained in the fluid dynamic pressure thrust bearing portion.
[0065]
In the recording disk drive motor according to the second aspect of the present invention, the shaft is fixedly fitted to the base portion of the rotor hub, and the fitting portion has a small diameter, and the axial fitting depth of the rotor hub. The axial dimension of the gap of the fluid dynamic pressure thrust bearing portion provided between the lower surface of the upper wall portion of the rotor hub and the upper end surface of the sleeve becomes uniform, and stable shaft support can be obtained. It becomes possible, and the rotation speed of the motor can be kept stable during rotation.
[0066]
In the recording disk drive motor of claims 3, 4 and 5 of the present invention, in addition to being able to obtain a stable shaft support force and maintain high rotational accuracy in the fluid dynamic pressure thrust bearing portion, When the lower surface of the upper wall portion of the rotor hub and the upper end surface of the sleeve are in contact with each other, the lower surface of the rotor hub and the upper end surface of the sleeve are subject to wear, damage, or seizure, resulting in motor durability and reliability. It can also prevent the deterioration of the sex.
[0067]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention. (First Example)
FIG. 2 is an enlarged cross-sectional view of a main part according to the first embodiment of the present invention.
FIG. 3 is an enlarged cross-sectional view of a main part according to a second embodiment of the present invention. (Second embodiment)
FIG. 4 is an enlarged sectional view of an essential part according to a third embodiment of the present invention. (Third embodiment)
FIG. 5 is a cross-sectional view showing a conventional recording disk driving motor.
[Explanation of symbols]
6, 106 sleeve
6a, 106a Upper end surface
8,108 shaft
8a, 108a Screw hole
8c Small diameter part
8d protrusion
12, 112 Rotor hub
12a, 112a Upper wall part
12a1 Projection
12, 112b peripheral wall
12c, 112c buttock
12d Circumferential protrusion
14,114 Fluid dynamic pressure thrust bearing
18, 118 Recording disc
20, 120 spacer
22, 122 Clamp member
22a, 122a Base
22a1 Projection
22b, 122b action part
24, 124 Fastening means
24a Large diameter part
24b Medium diameter part
24c Small diameter part
26, 126 First fluid dynamic pressure radial bearing
28, 128 Second fluid dynamic pressure radial bearing

Claims (5)

A rotor hub formed by a peripheral wall portion of the recording disc on the outer circumference are retained while hanging from the outer periphery of the substantially disk-shaped upper wall portion and the upper wall portion, said rotor hub and shaft that rotates integrally with the inner with the biasing pressure holds the fastening means proximal the periphery is screwed into a screw hole provided in the axial direction of the shaft, the action portion of the outer peripheral side abuts and presses the recording disc resiliently on the recording disc a clamp member, and a sleeve for supporting the shaft via a fluid dynamic bearing, between the upper end surface of the lower surface and the sleeve of the upper wall portion of the rotor hub, fluid dynamic thrust bearing portion is provided et al In the recording disk drive motor,
The clamp member further includes an annular intermediate portion that connects the base and the action portion,
A gap is formed between the annular intermediate portion and the rotor hub opposed to the annular intermediate portion, and between the upper wall portion and the base portion, respectively.
It said fastening means, with respect to the axial direction of the clamping member is the motor, as opposed to the rotor hub with the gap, the tightening amount of the axis Direction is restricted,
The recording disk drive motor according to claim 1, wherein an axial clearance between the annular intermediate portion and a rotor hub facing the annular intermediate portion is larger than an axial clearance between the upper wall portion and the base portion . 2. The shaft according to claim 1, wherein the shaft is fixedly fitted to a base portion of the rotor hub, and the fitting portion has a small diameter, thereby restricting a fitting depth in the axial direction of the rotor hub. The recording disk drive motor described. The base of the clamp member is provided with a protrusion that hangs inward in the axial direction from the lower end surface of the base and contacts the upper end surface of the shaft. The protrusion includes the fastening means and the upper end surface of the shaft. The recording disk drive motor according to claim 1, wherein the recording disk drive motor is clamped in the axial direction. The upper portion of the shaft is provided with a protruding portion that extends outward in the axial direction from the upper end surface of the upper wall portion of the rotor hub that is externally fitted and fixed to the shaft. The recording disk driving motor according to claim 1, wherein the recording disk driving motor is in contact with each other. A protruding portion extending radially inward from a fitting portion between the rotor hub and the shaft is provided at an inner inner end portion of the upper wall portion of the rotor hub, and the protruding portion is an upper end portion of the fastening means and the shaft. The recording disk drive motor according to claim 1, wherein the recording disk drive motor is sandwiched in the axial direction.

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