JP3621460B2 - Spindle motor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a spindle motor used for rotationally driving a recording disk such as an optical / magnetic disk.
[0002]
[Prior art]
For example, a spindle motor incorporated in a magnetic disk drive device is provided with a magnetic fluid seal device and a labyrinth seal structure for sealing the inside and outside of the motor, as disclosed in, for example, JP-A-4-295245. This prevents the unclean air inside the motor from leaking into the disk mounting space and contaminating the clean space.
[0003]
By the way, various disk drive devices are being reduced in size and increased in capacity. Accordingly, the spindle motor mounted inside the apparatus is required to be further reduced in size and thickness, and on the other hand, it has become necessary to support high speed rotation while maintaining required characteristics. In particular, the drive rotational speed of the disk has conventionally been 5,400 r. p. m from the upper limit of about m, 7,200 r. p. It is shifting to an ultra high speed range of m or more.
[0004]
As the motor rotates at a higher speed, the load applied to the bearing means for rotating and supporting the rotor hub, that is, ball bearings, dynamic pressure bearings, etc., increases the bearing rigidity, and the fluid lubricant enclosed inside rotates. It becomes easy to leak out of the bearing due to centrifugal force. The leakage of the fluid lubricant leaks according to the creeping portion of the member connected to the outside of the bearing separately from the conventional vaporized state and scattered outside the motor. On the other hand, adopting a larger bearing means to maintain the bearing rigidity increases the proportion of the motor inside and hinders downsizing of the motor, and in addition, the enclosed fluid lubricant also increases relatively. Therefore, the leakage degree of the fluid lubricant is further increased.
[0005]
[Problems to be solved by the invention]
As described above, in the spindle motor, the magnetic fluid seal device and the labyrinth seal structure conventionally employed are mainly sealing means for preventing leakage of unclean air, that is, vaporized contamination and gas. In addition, it has been difficult to sufficiently cope with the leakage of the fluid lubricant caused by the high-speed rotation of the motor. In addition, in order to maintain a predetermined bearing rigidity, it is necessary to secure a minimum bearing space inside the motor. It was difficult to provide the sealing means itself.
[0006]
The present invention has been made to solve the above-mentioned problems existing in the prior art, and the problem is that a fluid lubricant disposed in the bearing means corresponding to the high speed rotation. It is an object of the present invention to provide a spindle motor which can prevent leakage of the motor to the outside of the motor and which can be realized with a simple configuration and which can be improved in reliability and reduced in size.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a spindle motor according to the present invention is provided with a rotor hub on which a recording disk is mounted, a stationary member, and a rotor hub and the stationary member. In a spindle motor that is driven to rotate relative to the stationary member, the rotor hub is disposed at a position on the way from the interposed portion of the bearing means to the disk mounting portion of the rotor hub. leaky preventing means you prevents fluid lubricant from leaking to the disk mounting portion of the rotor hub is provided on the rotor hub, said leakage preventing means includes a surface of the rotor hub by an annular member attached to the rotor hub is formed between, and opens towards the axial center of the motor is an annular groove which can trap the fluid lubricant to the inside, And wherein the door.
[0008]
The leakage preventing means may include an absorbing member that absorbs a fluid lubricant in the annular groove .
[0009]
[Action]
According to the spindle motor of the present invention, there is provided leakage preventing means for preventing the fluid lubricant from the bearing means from leaking to the disk mounting portion of the rotor hub, and this leakage preventing means is provided from the interposition part of the bearing means to the rotor hub. It was provided on the way to the disk mounting part. Since this leakage prevention means is an annular groove that opens toward the center of the motor shaft and can capture the fluid lubricant therein, the fluid lubricant is stored in the annular groove and is transferred to the disk mounting portion of the rotor hub. Since it does not leak out, the space inside the disk is not contaminated.
[0010]
In addition, providing the leakage preventing means with an absorbing member is effective when the amount of fluid lubricant is large.
[0011]
【Example】
Embodiments of a spindle motor according to the present invention will be described in detail with reference to the following drawings. FIG. 1 shows a first embodiment of a spindle motor mounted on a magnetic disk drive, for example, and is a sectional view showing the whole. In FIG. 1, a shaft 1 constituting a stationary member is provided with screw holes at the upper and lower ends thereof, screwed into drive devices (not shown) (upper and lower bases), and both ends are fixedly supported. A projecting portion 8 projecting in the radial direction is integrally formed at a substantially central portion of the shaft 1, and the stator 6 is fixed via a holding member 19. A pair of ball bearings 3 and 4 are fitted on the upper side of the shaft 1.
[0012]
On the other hand, in the rotor hub 2 that is rotatably supported, for example, three discs (not shown) are externally fitted and mounted on the outer peripheral portion 9 having the maximum outer diameter, and the disc is received on the flange portion 10 that projects to the bottom. A cylindrical portion 11 formed coaxially is integrally provided inside the rotor hub 2, and bearings 3 and 4 are mounted in the cylindrical portion 11. A rotor magnet is annularly arranged inside the rotor hub so as to face the stator 6 in the radial direction. When a required signal is input to the stator 6, the rotor hub 2 is rotationally driven by electromagnetic interaction between the stator 6 and the rotor magnet 5.
[0013]
A magnetic fluid sealing device 7 is interposed on the upper side of the ball bearing 3 in the figure, and on the lower side of the ball bearing 4 are an outer peripheral portion 12 of the cylindrical portion 11 and an inner peripheral portion 13 of the stator 6. The labyrinth seal structure by proximity is comprised, and the inside and outside of a motor are sealed by these. The seal member 14 provided inside the rotor hub 2 is affixed to seal a screw hole for fixing the disk.
[0014]
A fluid lubricant leakage preventing portion 15 is provided at the lower end portion of the flange portion 10 of the rotor hub 2. The leakage prevention portion 15 is configured by attaching and fixing a ring-shaped plate 17 to the lower end portion of the flange portion 10 with an adhesive spacer 17, thereby forming an annular groove 36 that opens in the axial center direction of the motor. ing. The leakage preventing portion 15 is provided to prevent the fluid lubricant sealed in the ball bearing from leaking to the disk mounting side (the flange portion 10 side) of the rotor hub 2.
[0015]
In other words, in the illustrated example, a fluid lubricant such as grease mainly sealed in the ball bearing 4 is continuously provided from the cylindrical portion 11 (the outer peripheral portion 12 thereof) due to the centrifugal force received with the high speed rotation of the rotor hub 2. It tries to leak to the outer peripheral side of the rotor hub 2 through the inner peripheral part of the rotor magnet 5. In other words, the fluid lubricant gradually moves to the outside under the action of centrifugal force while maintaining the creeping surface connected from the ball bearing 4 inside the motor to the outside of the motor with the surface tension. However, the leakage preventive portion 15 provided at the lower end portion of the flange portion 10 captures the fluid lubricant in the annular groove 16 and stores it therein, and thus prevents leakage to the flange portion 10 side.
[0016]
Various plastic plates can be used as the plate 17 constituting the leakage preventing portion 15. A double-sided adhesive can be used for the adhesive spacer 15.
[0017]
FIG. 2 shown next is a spindle motor of the second embodiment, and is an overall cross section thereof. In FIG. 2, on the contrary to the embodiment of FIG. 1, the cylindrical portion 31 is fixed to a driving device (not shown) to serve as a stationary member. And a pair of ball bearings 23 and 24 are mounted in the cylindrical portion 31, and the shaft 21 inserted in the center thereof is rotatably supported. Further, a rotor hub 22 is coaxially formed integrally with the shaft 21. A disk (not shown) is received and fixed by the flange 20 of the rotor hub 22. In the illustrated example, a single disk is loaded. The stator 26 is disposed on the outer peripheral portion of the cylindrical portion 31, and the rotor yoke 29 and the rotor magnet 25 are mounted inside the rotor hub 22 so as to face the stator 26 in the radial direction.
[0018]
The lower end portion of the cylindrical portion 31 is sealed with a cap 33 attached. On the other hand, the ball bearing 23 and the stepped portion 27 on the rotor hub 22 side are provided on the upper side of the ball bearing 23 in the drawing, that is, on the motor outer side. The labyrinth seal structure is configured by the proximity. Further, in order to prevent the fluid lubricant from leaking from the ball bearing 23 side to the flange portion 20 of the rotor hub 22, a leakage preventing portion 35 is provided at the lower end portion of the flange portion 20.
[0019]
The leakage prevention part 35 is formed by bending a thin steel plate 37 as shown in the drawing, and is provided in an annular shape along the rotor hub 22. An annular groove 36 that opens toward the motor central axis is provided. In this case as well, similar to the embodiment of FIG. 1, the fluid lubricant from the ball bearing is provided to prevent leakage to the flange 20 side of the rotor hub 22. In FIG. 2, the fluid lubricant mainly from the ball bearing 23 tends to leak from the rotor magnet 25 and the rotor yoke 29 to the flange portion 20 side through the inner wall 28 of the rotor hub 22. For this reason, the fluid lubricant is captured and stored in the annular groove 36 by the leakage preventing portion 35 provided at the lower end portion of the flange portion 20. In addition, the fixing method with respect to the rotor hub 22 of the steel plate 37 can be fixed by adhesion | attachment, caulking, spot welding, or welding, and can be freely selected by the material of the member to be used.
[0020]
3 to 5 are enlarged cross-sectional views of the main part showing still another embodiment, both of which relate to the leakage preventing part provided at the lower end of the flange 30 of the rotor hub, and the leakage preventing part shown in FIGS. 15 and 35 show modified examples. In FIG. 3, a plate 34 that forms an annular groove 38 so as to open toward the central axis of the motor is provided by being bent in an L-shaped cross section. Depending on the material of the plate 34 to be attached, various fixing directions can be adopted in addition to adhesion and press fitting. The volume of the fluid lubricant that can be stored is determined by the length L (in the radial direction) and the length T (in the axial direction) that define the volume of the annular groove 38.
[0021]
This capacity is the same in FIGS. 1 and 2 and FIGS. 4 and 5 described below. For example, a predetermined dimension is set in advance corresponding to a fluid lubricant capacity that may leak. In this embodiment, the ball bearing has a very small grease capacity of several microliters, and therefore the L dimension and the T dimension are set to several millimeters. In particular, the T dimension needs to consider the thickness dimension of the material of the plate used, and the L dimension may be determined so as to correspond to the above capacity.
[0022]
Further, FIG. 4 shows an embodiment in which the flange portion 30 of the rotor hub is formed by plastic deformation processing using a steel plate, and thereby the annular groove 38 is formed. In FIG. 5, the plate 41 is attached to the lower end portion of the flange portion 30 via an adhesive spacer 42, and an absorption member 39 that absorbs the fluid lubricant is further provided in the annular groove 38 formed thereby. . For example, a resin porous member is used as the absorbing member 39, and the fluid lubricant trapped in the annular groove 38 is held by the absorbing member 39. In particular, when the holding amount is large, it is effective to use such an absorbing member. 1 to 5 shown above are configurations in which a leakage preventing portion for fluid lubricant is provided in the flange portion of the rotor hub, and in addition to those shown for the motor configuration and the leakage configuration, these can be used in combination. Needless to say.
[0023]
Next, FIG. 6 is a sectional view of a spindle motor on which, for example, 10 or more recording disks are mounted, and the right half is shown. In FIG. 6, the upper and lower ends of the shaft 43 are fixed to the apparatus, and the rotor hub 44 is rotatably supported via a pair of ball bearings 45 and 46 attached to the upper and lower portions of the shaft. Specifically, the rotor hub 44 having a bell shape is directly attached to the ball bearing 45 (the outer ring portion thereof) at the upper inner peripheral portion thereof. A ball bearing 46 is attached to the lower inner peripheral portion of the one through a bush 47. An annular member 56 interposed between the shaft 43 and the ball bearing 45 is a spacer provided to make the ball bearing 45 the same shape as the lower ball bearing 46.
[0024]
A stator 52 is mounted at a substantially central portion of the shaft 43, and a rotor magnet 53 is disposed on the inner side of the rotor hub 44 via a rotor yoke 54 so as to face the stator 52 in the radial direction. A magnetic fluid seal device 49 is interposed between the shaft 43 and the rotor hub 44 on the upper side of the ball bearing 45 in the drawing, that is, on the outside of the motor. Further, on the lower side of the ball bearing 46 in the drawing, that is, on the outside of the motor, a protruding portion 51 in which the lower portion of the bush 47 protrudes toward the shaft 43 is formed, and the shaft is opposed to the protruding portion 51 with a slight radial gap. A step portion 50 is formed on the 43 side. The overhang portion 51 and the step portion 50 constitute a labyrinth seal structure.
[0025]
Furthermore, in the present embodiment, the following fluid lubricant leakage prevention means is provided corresponding to the high-speed rotation of the motor. Corresponding to the ball bearing 45, an annular groove 60 having a substantially arc-shaped cross section is provided on the inner peripheral portion 70 of the rotor hub 44 (the stepped portion 59) on the outside of the motor. That is, when the fluid lubricant leaks on the side of the rotor hub 44 joined to the outer ring portion of the ball bearing 45, it is captured and stored in the annular groove 60. The leakage of the fluid lubricant enclosed in the ball bearing 45 moves to the annular groove 60 due to the centrifugal force acting by the rotation of the rotor hub 44.
[0026]
On the other hand, on the motor inner side of the ball bearing 45 (downward in the figure), a leakage preventing part 58 having an L-shaped cross section is formed on the lower side of the stepped part 59 in the figure. The leakage prevention portion 58 is formed with an annular groove that opens to the axial center side, as in the previously described embodiments. The configuration is the same as that shown in FIG. 3. As a result, the fluid lubricant leaks into the motor and leaks from the joint 65 between the rotor hub 44 and the bush 47 to the outside of the motor through the motor inner wall. It is to prevent. In order to prevent leakage from the joint portion 65, the sealing member 62 can be interposed between the rotor yoke 54, the rotor magnet 53 and the bush 47. The sealing member 62 is interposed in pressure contact, and an annular elastic member such as an O-ring can be used as the material.
[0027]
On the other hand, corresponding to the ball bearing 46, an annular groove 61 is formed in the inner peripheral portion 71 of the bush 47, and a leakage preventing portion 57 is formed on the motor inner side of the bush 47. Since these operations are the same as those of the annular groove 60 and the prevention portion 58, the description thereof is omitted.
[0028]
The embodiment shown in FIGS. 7 and 8 is a spindle motor having basically the same configuration as that shown in FIG. 6, and only differences from FIG. 6 will be described below. In addition, the same number is attached | subjected about the same site | part and member. First, in FIG. 7, annular grooves 67 and 68 are provided instead of the annular grooves 60 and 61 shown in FIG. 6, and both have a rectangular cross-sectional shape. Prevention unit 66,6 9 instead of the outflow preventing section 58 and 57 are provided also. Each is formed integrally with the rotor hub 44 to the bush 47 as shown in the figure. Further, in FIG. 7, an adhesive 76 is provided instead of the sealing member 62 of FIG. 6 to seal the joint portion 65. For example, when the rotor yoke 54 and the rotor magnet 53 are bonded and fixed to the inner peripheral portion 55 of the rotor hub 44, the adhesive 76 may be used in addition to filling the adhesive 76 into a predetermined portion independently. .
[0029]
In the embodiment of FIG. 8, prevention portions 72 and 73 are provided in place of the prevention portions 66 and 69 of FIG. 7, and the plates 74 and 75 constituting these are directly attached to the step portions 59 to the bush 47. Attached and fixed. As described above, various plastics can be used as the material for these plates.
[0030]
The spindle motor shown in FIG. 9 is still another embodiment and is a cross-sectional view showing the right half of the whole. In FIG. 9, labyrinth seal structures 93 and 94 are configured corresponding to the outside of the motors of the ball bearings 79 and 80, and the fluid lubricant is absorbed and held in order to prevent leakage of the fluid lubricant. Absorbing members 84, 85, 86, and 87 are disposed, respectively. In either case, the ball bearings 79 and 80 are fitted in the corresponding recesses of the rotor hub 77 and bush 82 corresponding to the inside and outside of the motor. The absorbing member 84, 85, 86, 87 may be used in combination with the already used annular groove for preventing fluid lubricant leakage. An annular groove 83 is formed in the joint portion 96 of the bush 82 with the rotor yoke 93, and can be used in place of the sealing members 62 and 76 configured in FIGS.
[0031]
The spindle motor shown in FIG. 10 is a further modification of FIG. 9, and basically has the same configuration. In FIG. 10, the ball bearings 79 and 80 are each covered with a cover member to prevent leakage of the fluid lubricant enclosed therein. That is, in the ball bearing 79, the cover 90 is mounted on the inner ring side, and the cover 89 is mounted on the outer ring side. Each of the covers 90 and 89 is provided so as to be divided in the axial direction so as to be easily assembled. The ball bearing 80 is also provided with covers 92 and 92, which are similarly divided in the axial direction. These covers may be made of synthetic rubber or the like in addition to the plastic material. In such a configuration, the already used annular groove for preventing leakage of fluid lubricant may be used in combination .
[0032]
As described above, various embodiments of the spindle motor using the ball bearing have been described. However, various means for preventing leakage of the fluid lubricant can be used by using them alone or in combination thereof. In this embodiment, the ball bearing in which the fluid lubricant is sealed has been described. Needless to say, the present invention can be applied to a fluid dynamic bearing structure having a fluid pressure generating groove in which the fluid lubricant is disposed. Also, other configurations of the spindle motor are not limited to the present embodiment.
[0033]
Each leakage prevention portion may be provided at least on the side where the centrifugal force of the rotor hub acts, that is, on the outer side of the motor.
[0034]
【The invention's effect】
Since the spindle motor of the present invention has the above-described configuration, the following effects can be obtained. According to the spindle motor of the present invention, the leakage preventing portion formed by the annular groove formed between the surface of the rotor hub and the annular member for preventing the fluid lubricant from the bearing from leaking to the disk mounting portion of the rotor hub is provided. The leakage prevention portion is provided at a location on the way from the bearing interposed portion to the disk mounting portion of the rotor hub. For this reason, since the fluid lubricant is captured and stored in the annular groove , the fluid lubricant does not leak to the disk mounting portion of the rotor hub, so that the disk chamber space is not contaminated.
[0035]
By providing an annular groove as the leakage preventing portion, the fluid lubricant is captured and stored in the annular groove . For this reason, in response to high-speed rotation of the motor, because the fluid lubricant disposed in the bearing means can be prevented from leaking to the outside of the motor, yet can be realized by a simple construction, improvement and size reduction of reliability Can be planned.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an entire spindle motor according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing an entire spindle motor according to a second embodiment of the present invention.
FIG. 3 is an enlarged sectional view showing a part of a spindle motor according to another embodiment of the present invention.
FIG. 4 is an enlarged sectional view showing a part of a spindle motor according to another embodiment of the present invention.
FIG. 5 is an enlarged sectional view showing a part of a spindle motor according to another embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a right half of a spindle motor according to another embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a right half of a spindle motor according to another embodiment of the present invention.
FIG. 8 is a cross-sectional view showing the right half of a spindle motor according to another embodiment of the present invention.
FIG. 9 is a sectional view showing a right half of a spindle motor according to another embodiment of the present invention.
FIG. 10 is a sectional view showing a right half of a spindle motor according to another embodiment of the present invention.
[Explanation of symbols]
1, 2, 43, 78 Shaft 2, 22, 44, 77 Rotor hub 3, 23, 45, 79 Ball bearing 4, 24, 46, 80 Ball bearing 5, 25, 53, 95 Rotor magnet 6, 26, 52, 94 Stator 7, 49 Magnetic fluid seal device 15, 35 Fluid lubricant leakage prevention part 16, 36 Annular groove 17 Plate 18 Adhesive spacer 19 Holding member

Claims (2)

A rotor hub on which a recording disk is mounted; a stationary member; and a bearing means provided between the rotor hub and the stationary member and having a fluid lubricant disposed therein. In the spindle motor driven to rotate relative to the member, the fluid lubricant leaks to the disk mounting portion of the rotor hub at a position on the way from the interposed portion of the bearing means to the disk mounting portion of the rotor hub. blocking to that leaky preventing means is provided in the rotor hub,
The leakage preventing means is formed between the surface of the rotor hub by attaching an annular member to the rotor hub, and opens toward the axial center of the motor so that the fluid lubricant can be captured inside. A spindle motor characterized by being a groove . The spindle motor according to claim 1, wherein the leakage preventing means includes an absorbing member that absorbs a fluid lubricant in the annular groove .

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