JP3182014B2 - Spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is used for rotationally driving a recording disk such as an optical / magnetic disk,
The present invention relates to a spindle motor provided with a dynamic pressure bearing.

[0002]

2. Description of the Related Art A spindle motor used for a recording disk drive such as a magnetic disk or an optical disk includes a hub member on which a recording disk is mounted, a shaft for rotating and supporting the hub member, a housing (or a bracket or the like). ). The hub member is driven to rotate relative to the housing. As a bearing means for the hub member, a fluid dynamic pressure bearing having high rotation accuracy and corresponding to a compact spindle motor is used, reflecting recent trends in miniaturization and high capacity of the device. Further, as a recording device, a hub member (hub member) in the direction of the rotation axis of the spindle motor is required due to the head operation for accessing the recording disk.
Strict precision is required for height position regulation. For this reason, in the spindle motor, a position regulating member for regulating the position in the rotation axis direction is provided on a shaft or the like, and is mounted so as to engage in the rotation axis direction. Japanese Patent Publication No. 63-43606 discloses an example of such a configuration of position regulation in the direction of the rotation axis. That is, the flange receiving the thrust (axial) load is
The shaft is mounted or integrally fixed to an end of the shaft or an intermediate portion of the shaft.

[0003]

However, in a spindle motor having such a configuration, required accuracy is required in the process of attaching the flange portion to the shaft or forming it integrally. It was troublesome and complicated. Further, when assembling the shaft provided with the flange portion to the housing, it is necessary to cover the flange portion with a lid, and processing and assembling the shape are troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to provide a hub for mounting a recording disk while having a relatively simple structure. An object of the present invention is to provide a highly reliable and highly productive spindle motor capable of minutely defining a change in the direction of a rotation axis of a member, and which can be easily assembled and reduce production costs.

[0005]

In order to achieve the above object, a spindle motor according to the present invention comprises a hub member on which a recording disk is mounted, and a stationary member, wherein the hub member is positioned with respect to the stationary member. A spindle motor that is driven to rotate relative thereto; a shaft portion having one end fixed and the other end being an open end is coaxially provided on the hub member; the shaft portion is inserted into the stationary member, A sleeve that rotatably supports the shaft; a shaft into which the shaft is inserted; a bottom of a hole of the sleeve that supports the shaft in a rotational axis direction through a lubricating fluid; First thrust bearing means for sucking an open end of the hub member to support the hub member in the direction of the rotation axis through a lubricating fluid in the opening of the hole, and The part that works by floating the corresponding part of It is made provided with a dynamic pressure type thrust bearing means.

It is desirable that the first dynamic pressure type thrust bearing means and the second dynamic pressure type thrust bearing means have different dynamic pressure generation areas.

When the rotation is stopped, the open end of the shaft portion is supported substantially in point contact with the bottom of the hole of the sleeve, and the opening of the hole of the sleeve is The corresponding portion of the hub member is provided with a gap in the rotation axis direction.

[0008]

According to the spindle motor of the present invention, the shaft of the hub member is rotatably supported by the sleeve of the stationary member with the relative rotation of the hub member and the stationary member. And
With the first dynamic pressure type thrust bearing means, the hub member (the shaft portion) is attracted and supported in the rotation axis direction with respect to the stationary member (the sleeve), while the second dynamic pressure type thrust bearing means. The hub member is supported so as to float in the rotation axis direction with respect to the stationary member (the sleeve thereof). By these first and second dynamic pressure type thrust bearing means, the hub member is brought into an equilibrium state at a predetermined position in the rotation axis direction with respect to the stationary member, and the hub member is relatively rotated while its position is regulated. Therefore, unlike the related art, there is no need to provide a flange portion or the like for regulating the position on the shaft portion, and the change in the rotation axis direction can be made small while the structure is simple. In addition, it is possible to reduce production costs such as processing and assembly.

Further, the dynamic pressure generating area of the first dynamic pressure type thrust bearing means can be made different from the dynamic pressure generating area of the second dynamic pressure type thrust bearing means to change the state of the thrust bearing support. For example, by increasing the size of the second dynamic pressure type thrust bearing means, in addition to the original thrust bearing support, the recording disk and other loads can be supported, and the required height position of the hub member can be defined. it can.

In addition, the open end of the shaft portion is supported substantially in point contact with the bottom of the hole of the sleeve,
Further, since the opening of the hole of the sleeve and the corresponding portion of the hub member are arranged with a gap, wear and damage of these dynamic pressure generating portions are prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle motor according to the present invention will be described with reference to FIGS. First, FIG.
1 is a first embodiment of a spindle motor for rotating a magnetic disk, for example, and is a sectional view showing the entirety thereof. In FIG. 1, a member 1 is an inverted bowl-shaped hub member on which a magnetic disk (recording disk) is mounted. The hub member 1 is made of, for example, stainless steel of a magnetic material, and the small diameter portion 36 is formed at the upper part of the figure, and the large diameter part 30 is formed at the lower part of the figure, coaxially and integrally. In the spindle motor according to the present embodiment, two donut-shaped magnetic disks are mounted, and the lower magnetic disk 35 in the drawing is placed in contact with the large-diameter portion 30 of the hub member 1. The upper magnetic disk 34 is provided with the clamp member 3.
9 secures it to the hub member 1 as well. More specifically, the lower end surface 62 of the magnetic disk 35 has a large diameter portion 30.
The hole 61 is fixed to the small-diameter portion 36 of the hub member 1 via the spacer 38 via the spacer 38. The spacer 38 is formed of an elastic resin material. An engaging portion 42 of the spacer 38, which is located on the upper side in the drawing and protrudes inward in the radial direction, is elastically engaged with the annular projection 41 on the outer peripheral wall 40 of the small diameter portion 36. The upper end surface of the magnetic disk 34 is held by the annular projection 43 of the clamp member 39 attached to the hub member 1 and held. Then, the hole is fixed to the small diameter portion 36 via the spacer 46. The spacer 46 is formed of the same shape and member as the spacer 38. Then, through the fitting portion 44 of the clamp member 39 and the annular projection 41 formed on the outer peripheral wall 40 of the small diameter portion 36,
It is engaged resiliently. As is clear from the figure, these magnetic disks 34 and 35 are attached and fixed to the small diameter portion 36 by spacers 46 and 38 symmetrically in the vertical direction in the figure. Note that the clamp member 39 is fixed to a hole 47 formed on the rotation axis 7 of the hub member 1 by a mounting screw 45. Thus, the magnetic disks 34 and 35
A predetermined height with respect to the hub member 1 is defined by contacting the end faces with the annular projections 43 and 37, respectively.
The magnetic disks 34 and 35 are mounted on the hub member 1 via spacers 46 and 38 made of a resin material, respectively. For this reason, the magnetic disks 34 and 35 are also prevented from being subjected to a distortion stress to the magnetic disks 34 and 35 even with respect to the shape distortion caused by the thermal expansion of the hub member 1, so that the magnetic disks 34 and 35 do not warp or deform.

A shaft 3 is integrally formed inward (downward in the figure) on the rotation axis 7 of the hub member 1.
A plurality of herringbone grooves 49 and 50 arranged in the circumferential direction are formed on the outer peripheral surface 14 of the shaft 3 at the top and bottom in the figure. The shaft 3 is inserted and held in the hole 6 of the sleeve 4. The sleeve 4 is formed from, for example, a lead alloy or the like. The sleeve 4 is fixed to a cylindrical portion 25 of the housing 2 which is a stationary member. The outer peripheral surface 26 of the sleeve 4 and the inner peripheral surface 27 of the cylindrical portion 25 are fixed by press-fitting or bonding in approximately half the space of the sleeve 4. this is,
In addition to being formed to substantially reduce the radial dimension of the small diameter portion 36 of the hub member 1, since the fixed space does not extend over the entire length of the sleeve 4, the sleeve 4
This is for preventing the opening dimension of the hole 6 from being distorted. The hole 6 of the sleeve 4 has an opening 9 on the upper side in the figure, and has a cylindrical shape whose lower side is closed by the bottom 8. Inside the hole 6, the inner diameter is set to a fitting dimension corresponding to the outer dimension of the shaft 3. Also the bottom 8
A communication hole 22 for communicating between the inside and the outside is formed, and an adhesive pool groove is formed outside the communication hole 22 (the lower side in the figure). A minute gap between the shaft 3 and the hole 6 of the sleeve 4 is filled with a lubricant as fluid lubrication. As a result, the lubricant is interposed between the herringbone grooves 49 and 50 provided on the outer peripheral surface 14 of the shaft portion 3 and the inner peripheral surface 15 of the hole 6 of the sleeve 4. A dynamic pressure type radial bearing for rotatably supporting the portion 3 is formed.
The communication hole 22 serves as an air vent when the shaft 3 is inserted into the hole 6 of the sleeve 4, and also serves as an injection hole for a lubricant injected into the hole 6 after the shaft 3 is inserted. Fulfill. After the injection of the lubricant, the communication holes 2 are
Block 2

An armature 16 is mounted on the outer peripheral side of the cylindrical portion 25 in the housing 2. The armature 16
The stator core 17 includes magnetic pole teeth provided with a predetermined number of poles in the circumferential direction, and a required number of electromagnetic steel sheets are laminated. The armature coil 19 is wound around the stator core 17. The inner peripheral portion of the armature 16 is a cylindrical portion 25 of the housing 2.
Is positioned and fixed to the outer peripheral step portion 24 formed at the bottom. Then, the coil lead wire 63 pulled out from the armature coil 19 is electrically connected to the flexible circuit board 20 provided to be attached to the bottom portion 28 of the housing 2. The flexible circuit board 20 is led out of the housing 2 to the outside of the spindle motor. A rotor magnet 21 is provided on the large-diameter portion 30 of the hub member 1 so as to face the armature 19 radially outward and close to the armature 19. The rotor magnet 21 has an N pole and an S pole in the circumferential direction on the inner peripheral wall 33 of the large diameter portion 30.
The poles and the predetermined number of poles are alternately arranged and fixed by bonding. Accordingly, when a required electric signal is input to the flexible circuit board 20 and the armature coil 19 is energized, the hub member 1 rotates relative to the housing 2 by the electromagnetic action of the armature 16 and the rotor magnet 21. Driven. In the illustrated example, the hub member 1 rotates clockwise with respect to the housing 2. In addition, the outer peripheral end of the stator core 17 in the armature 16 is formed by bending upward in the figure. The bent portion 18 is for matching the magnetic centers of the armature 19 and the rotor magnet 21. That is, the armature 19 is positioned relatively lower (lower in the drawing) in the direction of the rotation axis 7 with respect to the rotor magnet 21. The armature 19 is arranged below the housing 2 as low as possible, so that the height (thickness) dimension of the spindle motor is reduced. For this reason, in order to prevent the lower part of the armature coil 19 from contacting the bottom part 28 of the housing 2, a groove is formed in the corresponding part of the armature coil 19 in the bottom part 28.

The open end of the shaft 3, that is, the tip 5,
A spiral groove 51 shown in FIG. FIG. 2A is a plan view showing a state in which the distal end portion 5 of the shaft portion 3 is viewed from above from below in FIG. A minute gap between the spiral groove 51 of the shaft portion 3 and the bottom portion 8 opposed to the spiral groove is filled with a lubricant, and these constitute a dynamic pressure thrust bearing (referred to as a first dynamic pressure thrust bearing). ing. Therefore, when the shaft portion 3 (hub member 1) rotates in the direction of the arrow shown in FIG. 2, the shaft portion 3 (hub member 1) moves so as to be sucked to the bottom 8 (downward in FIG. 1). Pressure acts. On the other hand, a spiral groove 52 shown in FIG. 2B is provided on the opening end face 13 of the opening 9 in the sleeve 4. FIG. 2B is a plan view showing a state in which the opening 9 is viewed from above in FIG. 1 to below. A lubricant is interposed in the minute gap between the opening end face 13 and the corresponding portion 12 of the hub member 1 facing the opening end face 13 in the direction of the rotation axis 7, so that a dynamic pressure thrust bearing (second dynamic Pressure thrust bearing). For this reason, when the shaft 3 rotates in the direction of the arrow as shown in FIG. 2A, the sleeve 4 (still stationary) relatively rotates in the direction of the arrow shown in FIG. 2B. . With the rotation of the shaft portion 3, a dynamic pressure acts so that the hub member 1 floats on the sleeve 4 (upward in FIG. 1). Therefore, the hub member 1 is held in equilibrium at a predetermined height position (in the direction of the rotation axis 7) with respect to the housing 2 as a stationary member by the first and second dynamic pressure type thrust bearings 10, 10 and 11. You.
The dynamic pressure of the second hydrodynamic thrust bearing 11 is larger than that of the first hydrodynamic thrust bearing 10 (as is clear from FIG. 2, the effective area of the spiral groove is larger at 52 than at 51). Therefore, even if the weight of the hub member 1 and the weight of the magnetic disks 34 and 35 are raised, the hub member 1
Is maintained and defined at a predetermined height position. That is, in the spindle motor of the present invention, the dynamic pressure generating forces of the first dynamic pressure thrust bearing and the second dynamic pressure thrust bearing are made different (in the embodiment, the second dynamic pressure thrust bearing is connected to the first dynamic thrust bearing). It is possible to maintain and regulate the height direction of the hub member 1 while supporting a required load while increasing the dynamic pressure generating force as compared with the pressure type thrust bearing. During the rotation of the hub member 1, the dynamic pressures of the first and second dynamic pressure type thrust bearings 10 and 11 are maintained in an equilibrium state, so that a change in the height position is slightly defined. Moreover, its height position is stable. Even when the spindle motor is turned in the reverse direction, the hub member 1 does not easily fall off the sleeve 4 (hence, the housing 2) because the shaft portion 3 is held in a sealed state with respect to the sleeve 4. As described above, in the spindle motor according to the present invention, there is no need to provide a conventional position regulating member for defining the axial direction. In addition, the structure is simple, and the processing and assembly accompanying the structure is easy. The tip 5 of the shaft 3 is formed so that the center of rotation slightly protrudes. When the hub member 1 (the shaft 3) stops rotating, the tip 5 substantially comes into contact with the bottom 8 in a point contact manner. In contact. Therefore, the spiral groove 51 provided in the tip 5 of the shaft 3
Does not come into direct contact with the bottom portion 8 even when the rotation is started or stopped, so that damage due to abrasion is prevented and durability is improved. When the rotation is stopped, the lubricant filled between the shaft end 3 and the sleeve 4 at the opening end surface 13 and the hub member 1 can be easily leaked.
2 is provided with a gap. Therefore, the spiral groove 52 does not always contact the corresponding portion 12, so that damage due to abrasion is prevented. Even if it does not come out, even if it leaks out from the opening 9 of the sleeve 4, the housing 2 has a pot-like shape and is retained and held. Moreover, since the circumferential wall 32 (the housing 2) and the outer peripheral wall 31 (the large-diameter portion 30 of the hub member 1) are disposed close to each other and opposed to each other, the labyrinth seal structure constituted by these components allows the lubricant to be removed from the disk chamber space. No leakage to 48.

FIG. 3 shows a second embodiment of the spindle motor according to the present invention, and is a sectional view showing the whole of the embodiment. The same parts as those of the spindle motor of the first embodiment shown in FIG. 1 are denoted by the same reference numerals. The second embodiment in FIG. 3 has almost the same configuration as the first embodiment already described in detail, and therefore, only different portions will be described below. In FIG.
Has a hole 6 penetrating therethrough, and a lower portion thereof is closed by a thrust plate 53. The thrust plate 53 is provided with a communication hole 55 for communicating the inside and the outside (vertical direction in the figure). In order to close the communication hole 55, a seal member 56 is fixed to the lower end surface 57 of the housing 2 by sticking. In the lower part of the outer periphery of the step portion 60 of the sleeve 4,
An annular member 58 is fixed to the inner peripheral wall 59 of the hub member 1 by bonding. The annular member 58 is for preventing the hub member 1 from falling out of the sleeve 4 and dropping out, for example, in the case where the spindle motor is turned in the opposite direction, for example. In the spindle motor according to the second embodiment, the shaft 3 is inserted in the sleeve 4 in advance, and then the annular member 58 is attached to the hub member 1.
A lubricant is injected into the hole 6 of. When injecting lubricant,
Once the spindle motor is changed from the position shown in the figure to the opposite direction, the hub member 1 tends to come off the sleeve 4 at that time. This is because the sleeve 4 is different from the first embodiment and the hole 6 penetrates. However, the annular member 58 prevents the hub member 1 from falling off the sleeve 4. Needless to say, the annular member 58 is useful for preventing rotation during normal rotation and for preventing the spindle motor from coming off during handling. A lubricant is injected into the hole 6 of the sleeve 4, and a minute gap between the inner peripheral surface 15 of the hole 6 and the outer peripheral surface 14 of the shaft 3 is filled with a required amount. Next, the thrust plate 53 is connected to the (cylindrical portion 25) of the housing 2.
The lid is plugged into the hole 54 and closed. At this time, air is easily left as bubbles in the filled lubricant. If air bubbles remain in the lubricant, the bubbles expand due to a rise in temperature or the like during operation of the spindle motor, whereby the filled lubricant is pushed out from the opening 9 of the sleeve 4. However, since the trapped air can be released by the communication holes 55 provided in the thrust plate 53, leakage of the lubricant can be avoided. Similarly to the first embodiment, the spindle motor of the second embodiment includes both the first dynamic pressure type thrust bearing 10 and the second dynamic pressure type thrust bearing 11 and has the same configuration. The first and second hydrodynamic thrust bearings 10 and 11 balance and maintain and regulate the dynamic pressure at a predetermined position in the direction of the rotation axis 7. In this case, the same operation and effect as those of the first embodiment are obtained.

Although the embodiment of the spindle motor according to the present invention has been described in detail above, the present invention is not limited to this.
Changes and the like can be freely made within the scope of the present invention. For example, in the spindle motor according to the first embodiment, the herringbone grooves 49 and 50 are provided on the outer peripheral surface 14 of the shaft 3 as a dynamic pressure type radial bearing.
May be provided on the inner peripheral surface 15 side. Further, although the spiral groove 51 is provided in the distal end portion 5 of the shaft portion 3 as the first dynamic pressure type thrust bearing 10, a spiral groove may be provided on the bottom 8 surface side facing the spiral groove 51. Similarly, the second
Of the dynamic thrust bearing 11 of FIG.
Needless to say, 2 may be provided on the corresponding portion 12 of the hub member 1 in place of the opening end face 13 of the sleeve 4. The same applies to the second embodiment. Further, the shape and the number of grooves for generating dynamic pressure in these embodiments are freely designed and can be arbitrarily selected.
In addition, the dynamic pressure generation area can be variously changed and set according to the number of recording disks, the direction in which the load acts, and the like.

[0017]

Since the spindle motor according to the present invention has the above-described structure, the following effects can be obtained. That is,
Unlike the related art, there is no need to provide a flange portion or the like for regulating the position in the rotation axis direction on the shaft portion. Therefore, while the structure is relatively simple, the change in the direction of the rotation axis of the hub member on which the recording disk is mounted can be slightly defined, and the assembly is easy. Therefore, a highly reliable and highly productive spindle motor that can greatly reduce production costs including processing costs can be obtained.

[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 plan view showing a part of the spindle motor shown in FIG.

FIG. 3 is a sectional view showing the entirety of a spindle motor according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hub member 2 Housing (stationary member) 3 Shaft 4 Sleeve 6 Hole 7 Rotation axis 9 Opening 10 First dynamic pressure type thrust bearing 11 Second dynamic pressure type thrust bearing 16 Armature 21 Rotor magnet 22, 55 Communication hole 34, 35 Magnetic disk 39 Clamp member

Claims (3)

(57) [Claims] A hub member on which a recording disk is mounted;
A stationary member, wherein the hub member is a spindle motor that is driven to rotate relative to the stationary member, wherein the hub member has one end fixed and the other end open end coaxially. The stationary member is provided with a sleeve in which the shaft is inserted, and a sleeve for rotatably supporting the shaft is provided. The bottom of the hole of the sleeve into which the shaft is inserted is provided with a lubricating fluid. And a first dynamic pressure type thrust bearing means for supporting the shaft portion in the direction of the rotation axis and suctioning the open end of the shaft portion to act. The opening of the hole is provided with a lubricating fluid. A second dynamic pressure type thrust bearing means for supporting the hub member in the direction of the rotation axis and for raising a corresponding portion of the hub member to float. 2. The first dynamic pressure type thrust bearing means,
2. The spindle motor according to claim 1, wherein a dynamic pressure generation area is different from that of the second dynamic pressure type thrust bearing means. 3. When the rotation is stopped, the open end of the shaft portion is supported substantially in point contact with the bottom of the hole of the sleeve, and the opening of the hole of the sleeve; 2. The spindle motor according to claim 1, wherein the corresponding portion of the hub member is disposed with a gap in a rotation axis direction.