JP2015158229A - Pivot bearing unit - Google Patents

Abstract

Provided is a pivot bearing unit that can reduce the number of parts, can be easily designed, can reduce the axial length, and can reduce the thickness of an HDD. An outer ring spacer 60 is disposed between outer rings 43 and 53 of a pair of deep groove ball bearings 40 and 50, and an axial clearance S is formed between the pair of inner rings 41 and 51. Further, a labyrinth gap C is formed between the inner peripheral surface 64 of the outer ring spacer 60 and the outer peripheral surfaces 41 a and 51 a of the inner rings 41 and 51. [Selection] Figure 1

Description

  The present invention relates to a pivot bearing unit, and more particularly to a pivot bearing unit that swingably supports a swing arm of a hard disk drive device.

  FIG. 3 shows a schematic configuration of a hard disk drive (Hard Disc Drive (hereinafter also referred to as HDD)) as an example. The HDD includes a magnetic disk (hard disk) 2 that records information (data), a spindle motor 4 that rotates the magnetic disk 2, a swing arm 8 as an actuator having a magnetic head 6 attached to the tip, and a swing arm 8. And a voice coil 9 that rotationally drives the swing arm 8.

  The swing arm 8 is pivotally supported on the base Bs of the HDD via a pivot bearing unit 10 so as to be rotatable. When the swing arm 8 is rotationally driven by the voice coil 9, the magnetic head 6 with respect to the rotating magnetic disk 2. Is translated (traced). As a result, information is read from or written to the magnetic disk 2 via the magnetic head 6.

  As shown in FIGS. 4 and 5, the pivot bearing unit 10 includes a shaft member 12 erected on the base Bs of the HDD, and a precision miniature that is preloaded and fitted to the shaft member 12 side by side in the axial direction. And a pair of rolling bearings 20 and 30 which are bearings. These rolling bearings 20 and 30 include inner rings 21 and 31 and outer rings 22 and 32, and balls 23 and 33 as a plurality of rolling elements that are rotatably incorporated between the inner rings 21 and 31 and the outer rings 22 and 32. Prepare.

  In such a pivot bearing unit 10, a fixed position preload is generally used in which a load is applied to the inner rings 21 and 31 of the combined rolling bearings 20 and 30, and the positions of the inner and outer rings are fixed in that state. Conventional bearing devices are known in which the width of the outer ring is made wider than the width of the inner ring, or a spacer is arranged on the outer ring side so that the inner rings do not contact each other when preload is applied. (For example, refer to Patent Document 1).

  The pivot bearing unit 10 shown in FIG. 4 has a configuration in which the outer rings 22 and 32 of the pair of rolling bearings 20 and 30 are extended inward in the axial direction, and the outer rings 22 and 32 wider than the inner ring width are abutted against each other. The inner rings 21 and 31 are fixed to the shaft member 12 in a state where the inner rings 21 and 31 are pressed in a direction approaching each other in the axial direction, and preload is applied. Further, non-contact type shield plates 25 and 35 for sealing the inside of the bearing are arranged at the outer ends of the outer rings 22 and 32 in the axial direction. This prevents intrusion of foreign matter (for example, dust) from the outside of the bearing and prevents leakage of the grease composition sealed inside the bearing to the outside of the bearing.

  In the pivot bearing unit 10 shown in FIG. 5, in the rolling bearings 20 and 30, the outer ring spacer 14 is fitted between the outer rings 22 and 32 and preload is applied. Further, the rolling bearings 20 and 30 are constituted by general rolling bearings in which shield plates 25 and 35 are arranged at both axial ends, respectively.

Japanese Patent Laid-Open No. 10-318255

  By the way, in recent years, with the miniaturization of mobile personal computers, HDDs have been made thinner. As the HDD becomes thinner, there is a strong demand for a thinner pivot bearing unit that supports the swing arm.

  According to the pivot bearing unit shown in FIG. 4, there is a merit that there is little possibility of interference between parts and the number of parts is reduced. However, even if a shield plate is disposed at the abutting side end of the outer rings 22 and 32, there is a problem that the shield plate does not function effectively because the inner ring width is short. Further, since the shape of the bearings 20 and 30 affects the overall height of the pivot bearing unit 10, it is necessary to redesign the rolling bearings 20 and 30 in order to reduce the thickness of the unit.

  Further, according to the pivot bearing unit shown in FIG. 5, the shield plates 25 and 35 can be used, and the height dimension of the outer ring spacer 14 can be changed without changing the bearings 20 and 30. The height of the pivot bearing unit 10 can be freely changed. However, since the outer ring spacer 14 is added, the number of parts increases. Furthermore, the outer ring spacer 14 needs to be provided with spigot fitting portions 22a and 32a for center alignment on the inner diameter side of the abutting surface with the outer rings 22 and 32, but in a limited axial space. In order to avoid interference between the shield plate 35 and the spigot fitting portions 22a and 32a, the design may be difficult.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the number of parts and to simplify the design, reduce the axial length, and reduce the thickness of the HDD. It is to provide a bearing unit.

The above object of the present invention can be achieved by the following constitution.
(1) a shaft member;
An inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and a sealing member disposed at one end in the axial direction of the outer ring; A pair of rolling bearings each comprising:
An outer ring spacer sandwiched between outer rings of a pair of rolling bearings;
A pivot bearing unit comprising:
An axial clearance is formed between the inner rings of the pair of rolling bearings, and
A pivot bearing unit, wherein a labyrinth gap is formed between an inner peripheral surface of the outer ring spacer and an outer peripheral surface of the inner ring.
(2) The outer ring spacer is provided with an extending part that extends on the inner diameter side of the clamping part that is clamped between the outer rings and on both sides in the axial direction of the clamping part,
The pivot bearing unit according to (1), wherein the pair of outer rings are provided with annular recesses that are respectively fitted to the extending portions on the side surfaces facing each other.

  According to the pivot bearing unit of the present invention, by providing the outer ring spacer, an axial clearance is formed between the inner rings of the pair of rolling bearings. Therefore, by applying a load to the inner ring side of the rolling bearing, A position preload can be applied. In addition, since a labyrinth gap is formed between the inner peripheral surface of the outer ring spacer and the outer peripheral surface of each inner ring, a seal that seals between the inner and outer rings at the axial inner ends of the pair of rolling bearings It has a function. Therefore, the outer ring spacer has a function as a spacer and a sealing function at the same time, and the number of parts can be reduced, the design can be simplified, and the axial length of the pivot bearing unit can be shortened. This also makes it possible to reduce the thickness of the HDD.

It is sectional drawing of the pivot bearing unit which concerns on this invention. It is sectional drawing of the pivot bearing unit of a modification. (A) is sectional drawing which shows schematic structure of a hard-disk drive apparatus, (b) is a top view. It is an expanded sectional view of the conventional pivot bearing unit. It is an expanded sectional view of other conventional pivot bearing units.

  Hereinafter, an embodiment of a pivot bearing unit according to the present invention will be described in detail with reference to the drawings. The pivot bearing unit of this embodiment is also applied to the hard disk drive device shown in FIG.

  FIG. 1 is a sectional view of a pivot bearing unit of the present invention. As shown in FIG. 1, the pivot bearing unit 10 includes a shaft member 30 having a flange portion 31 at one axial end, a pair of deep groove ball bearings 40 and 50, and an outer ring spacer 60. The pair of deep groove ball bearings 40 and 50 are fitted to the shaft member 30 and arranged side by side in the axial direction.

  The pair of deep groove ball bearings 40, 50 includes inner rings 41, 51 having inner ring raceway surfaces 42, 52 formed on the outer circumferential surface, and outer rings 43, 53 having outer ring raceway surfaces 44, 54 formed on the inner circumferential surface, respectively. , A plurality of balls 45, 55 that are rolling elements disposed between the inner ring raceway surfaces 42, 52 and the outer ring raceway surfaces 44, 54, and a holder 46 that holds the balls 45, 55 rotatably. 56.

  Shield plate mounting grooves 43a, 43b, 53a, 53b, which are annular recesses, are formed at both axial ends of the inner peripheral surfaces of the outer rings 43, 53. When the pair of deep groove ball bearings 40 and 50 are arranged side by side in the axial direction, the outer peripheral side of the shield plates 47 and 57 which are sealing members is provided in the shield plate mounting grooves 43a and 53a which are axially outer ends, respectively. The edges are engaged. Thereby, the shield plates 47 and 57 seal the bearing unit 10 between the inner peripheral edge of the shield plates 47 and 57 and the outer peripheral surface of the inner rings 41 and 51. The shield plates 47 and 57 are configured not to contact the outer peripheral surfaces of the inner rings 41 and 51, but a sealing member (such as rubber) that contacts the outer peripheral surfaces of the inner rings 41 and 51 can also be employed.

The outer ring spacer 60 includes a clamping part 61 that is clamped between the outer rings 43 and 53, and an extending part 62 that extends on the inner diameter side of the clamping part 61 and on both sides in the axial direction of the clamping part 61. Are formed in an annular shape with a substantially convex cross section. The extending portion 62 has an outer diameter substantially equal to the innermost diameter of the shield plate mounting grooves 43b and 53b of the outer rings 43 and 53, and fits into the shield plate mounting grooves 43b and 53b. Further, the extending portion 62 has an inner diameter slightly larger than the outer diameter of the inner rings 41 and 51, and between the inner peripheral surface 64 of the outer ring spacer 60 and the outer peripheral surfaces 41 a and 51 a of the inner rings 41 and 51, A labyrinth gap C is formed. Further, on both side surfaces of the extension portion 62, relief portions 63 are formed in portions that have a smaller diameter than the portions that abut against the side surfaces of the shield plate mounting grooves 43 b and 53 b of the outer rings 43 and 53. The axial width is narrow.
The outer rings 43, 53 have the same shape and the same inner diameter as the shield plate mounting grooves 43 a, 53 b, 43 b, 53 a, so that the exchange workability between the shield plates 47, 57 and the outer ring spacer 60 is improved. The cost of producing 53 can be reduced.

  The pivot bearing unit 10 is assembled by fitting one of the deep groove ball bearings 50 to the shaft member 30 and fixing the inner ring 51 to the shaft member 30 by press-fitting or using an adhesive with the inner ring 51 and the flange portion 31 in contact with each other. To do. Next, after the extended portion 62 of the outer ring spacer 60 is fitted into the shield plate mounting groove 53 b of the outer ring 53, the outer ring 43 is shielded while the inner ring 41 of the other deep groove ball bearing 40 is fitted to the shaft member 30. The extending portion 62 is fitted into the mounting groove 43b. Then, in a state where the inner ring 41 of the deep groove ball bearing 40 is pressed in the direction of arrow A and preload is applied, the inner ring 41 is fixed to the shaft member 30 by press-fitting or adhesive, and so-called fixed position preload is employed. A sleeve (not shown) may be fitted on the outer peripheral surfaces of the outer rings 43 and 53.

  Thus, the pivot bearing unit 10 assembled by sandwiching the clamping portion 61 of the outer ring spacer 60 between the pair of outer rings 43 and 53 is maintained while the distance between the outer rings 43 and 53 is maintained by the outer ring spacer 60. An axial clearance S is formed between the inner rings 41 and 51 to apply a fixed position preload to the pair of deep groove ball bearings 40 and 50. Further, the inner peripheral surface 64 of the outer ring spacer 60 and the outer peripheral surfaces 41 a and 51 a of the inner rings 41 and 51 form a labyrinth gap C.

  In addition, as a pair of deep groove ball bearings 40 and 50 used for the pivot bearing unit 10, it is natural that a dedicated bearing can be used, but a general member in which a sealing member is removed from one side surface. A bearing with a sealing member can be used, and the cost can be significantly reduced. Further, by changing the width of the clamping portion 61 of the outer ring spacer 60, the height of the pivot bearing unit 10 can be easily changed according to the thickness of the HDD.

  As described above, according to the bearing unit 10 of the present embodiment, the axial clearance S is formed between the inner rings 41 and 51 of the pair of deep groove ball bearings 40 and 50 by providing the outer ring spacer 60. In addition, since the labyrinth gap C is formed between the inner peripheral surface 64 of the outer ring spacer 60 and the outer peripheral surfaces 41a and 51a of the inner rings 41 and 51, the outer ring spacer 60 functions as a spacer. A sealing function for sealing between the inner and outer rings is provided at the same time, the number of parts is reduced, and the axial length of the pivot bearing unit 10 can be shortened. This also makes it possible to reduce the thickness of the HDD.

  Further, the outer ring spacer 60 includes an extension part 62 that extends on the inner diameter side of the clamping part 61 that is clamped between the outer rings 43 and 53 and extends on both sides in the axial direction of the clamping part 61. The side surfaces of the outer rings 43 and 53 facing each other are provided with shield plate mounting grooves 43b and 53b that are fitted to the extending portions 62, respectively, so that the relative positions of the outer ring spacer 60 and the outer rings 43 and 53 are fitted by inlay fitting. Can be positioned, and assembly becomes easy.

(Modification)
As a modification of the present embodiment, the outer ring spacer 60 may be formed in a rectangular shape that does not include the escape portion 63 in the extension portion 62 as shown in FIG. The outer ring spacer 60 is applied to the pivot bearing unit 10 in which there is no possibility of interference between the extending portion 62 and the balls 45 and 55 and the cages 46 and 56.

Note that the present invention is not limited to the above-described embodiments and modifications, and modifications, improvements, and the like can be made as appropriate.
Moreover, in this embodiment, although the annular recessed part which the extension part 62 of the outer ring spacer 60 fits is formed by the shield plate attachment grooves 43b and 53b formed in the axial direction inner end part of the outer ring, The shape is not limited, and the extending portion 62 of the outer ring spacer 60 may be in a shape that fits with a spigot.

10 Pivot bearing unit 30 Shaft member 40, 50 Deep groove ball bearing (rolling bearing)
41, 51 Inner ring 41a, 51a Inner ring outer peripheral surface 43, 53 Outer ring 43a, 43b, 53a, 53b Shield plate mounting groove (annular recess)
45,55 balls (rolling elements)
47,57 Shield plate (sealing member)
60 Outer ring spacer 61 Clamping part 62 Extension part 63 Escape part 64 Inner circumferential surface C of outer ring spacer C Labyrinth gap S Axial direction gap

Claims (2)

A shaft member;
An inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and a sealing member disposed at an outer end in the axial direction of the outer ring; A pair of rolling bearings each comprising:
An outer ring spacer sandwiched between the outer rings of the pair of rolling bearings;
A pivot bearing unit comprising:
An axial gap is formed between the inner rings of the pair of rolling bearings, and
A pivot bearing unit, wherein a labyrinth gap is formed between an inner peripheral surface of the outer ring spacer and an outer peripheral surface of the inner ring. The outer ring spacer is provided with an extending portion that extends on the inner diameter side of the sandwiching portion sandwiched between the outer rings and extends on both sides in the axial direction from the sandwiching portion,
2. The pivot bearing unit according to claim 1, wherein the pair of outer rings are provided with annular recesses that are respectively fitted to the extending portions, on the side surfaces facing each other.

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