JP2017020636A - Pivot assembly bearing and disc drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pivot assembly bearing capable of being easily assembled at low cost, and stably obtaining a sufficient dust emission suppression effect.SOLUTION: For a pivot assembly bearing 10A, a sleeve 20 and a shaft 40 inserted into the sleeve 20 are provided in a relative rotatable manner through a pair of rolling bearings 30 mounted therebetween, and a seal plate 50 is in an axial end part so as to be fastened to an inner peripheral surface 23 of the sleeve 20, wherein a fluid seal 70 for suppressing dust emission is provided in a second labyrinth gap (seal gap) 62 formed between an inner peripheral surface 53 of the seal plate 50 and an outer peripheral surface 42 of the shaft 40.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a pivot assembly bearing used in a magnetic disk drive or the like, and more particularly to a seal structure using a seal gap.

  The pivot assembly bearing generally has a structure in which a sleeve is rotatably supported on the outer periphery of a shaft via a rolling bearing, and the rolling bearing is often provided in a pair of states separated in the axial direction. . In such a pivot assembly bearing, in recent years, there has been a strong demand for improvement against dust generation due to leakage or evaporation of oil contained in the lubricant filled therein. In other words, when dust generation material adheres to a medium or a magnetic head, a read / write error occurs. Therefore, it is considered that suppression of dust generation has a positive effect on the life and failure rate. In particular, it is said that the required level of dust generation suppression is more severe for pivot assembly bearings applied to hard disk drive devices for servers.

  Therefore, as a measure against dust generation, an annular seal member is provided between the shaft and the sleeve at both ends in the axial direction or a flange portion integrated with the shaft is provided, and a labyrinth-like gap is provided between the seal member and the flange. What is formed between a part and a rolling bearing and a shaft is known (patent documents 1, 2, etc.). Further, a proposal has been made to provide a magnetic fluid seal between the sleeve and the shaft (Patent Document 3). These dust generation measures also function as a means for suppressing foreign matter from entering the bearing from the outside.

JP 2006-077924 A JP 2008-069920 A JP 2002-027701 A

  Among the above dust generation countermeasures, even in the case of the labyrinth, in the case of the former, there is a minute gap, and thus it is not possible to completely suppress dust generation caused by the flow of air passing through the gap. In the latter magnetic fluid seal, since the magnetic fluid is filled in the gap, there is no gap through which air flows, but there are problems that the cost of the magnetic fluid seal is high and that a special process is required during assembly.

  The present invention has been made in view of the above, and a main object thereof is to provide a pivot assembly bearing that can stably obtain a sufficient dust generation suppressing effect while being easy to assemble. is there.

  A pivot assembly bearing according to the present invention includes a sleeve, a shaft, a rolling bearing disposed between the sleeve and the shaft, and a first seal member disposed on the axially outer side of the rolling bearing. And holding the lubricating fluid over the entire circumference of the annular seal gap formed between the first seal member and the sleeve or between the first seal member and the shaft. Features.

  According to the pivot assembly bearing of the present invention, since the sealing fluid is sealed by holding the lubricating fluid over the entire circumference by the action of capillary force in the annular sealing clearance, a sufficient dust generation suppressing effect can be obtained. It can be obtained stably. Sealing with lubricating fluid using the action of capillary force does not require magnets or expensive magnetic fluids, so the material cost is lower than magnetic fluid seals and no special process is required during assembly. It is advantageous in terms of cost and ease of manufacture over the seal.

  In the first seal member, the annular surface facing the annular seal gap is formed such that at least the annular seal gap does not widen toward the axial center of the annular surface. Including. According to this embodiment, since the capillary force acts toward the axial central portion of the annular surface, the lubricating fluid is easily held in the seal gap due to the capillary phenomenon, and the loss from the seal gap is suppressed, resulting in a more stable operation. The sealing function is demonstrated. As a specific example of this form, there is a form in which the annular surface is formed to have a convex cross section toward the axially central portion of the annular surface. In this embodiment, the lubricating fluid is likely to gather toward the axial center of the annular surface due to capillary action, and is more effectively held in the seal gap. Further, as a form for obtaining the same effect, a form in which a corner portion between the end face of the first seal member and the annular face is formed in a tapered shape can be mentioned.

  Moreover, this invention makes it a preferable form to provide the 2nd seal member which covers the said seal gap | interval on the axial direction outer side of a said 1st seal member, in order to acquire the further dust generation suppression effect. Thereby, evaporation and scattering of the lubricating fluid held in the seal gap can be suppressed.

  Next, a disk drive device according to the present invention includes the pivot assembly bearing according to the present invention described above, which swingably supports a magnetic head arm that moves a magnetic head on the magnetic disk.

  According to the present invention, it is possible to provide a pivot assembly bearing that can stably obtain a sufficient dust generation suppressing effect while being easy to assemble at low cost.

(A) The perspective view which shows the hard-disk drive device with which the pivot assembly bearing which concerns on one Embodiment was applied, (b) It is a perspective view of a pivot assembly bearing. 1 is an overall cross-sectional view of a pivot assembly bearing according to an embodiment. It is a partially expanded sectional view which shows the labyrinth clearance gap formed in the edge part of the right side of FIG. It is a partially expanded sectional view of the edge part of the left side of FIG. It is sectional drawing which shows the state of the labyrinth clearance gap formed in the part shown in FIG. 4, and the seal | sticker by oil. It is a whole sectional view of a pivot assembly bearing concerning other embodiments of the present invention. It is sectional drawing which shows the state of the seal by the oil of other embodiment. It is sectional drawing which shows the example of a shape of the internal peripheral surface (annular surface) of a sealing plate (1st sealing member).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Configuration of One Embodiment FIG. 1A shows a hard disk drive 1 that is one of storage devices of a computer to which a pivot assembly bearing 10A according to an embodiment is applied. In this hard disk drive 1, information is transferred to the magnetic disk 5 by moving the magnetic head 4 provided at the tip of the magnetic head arm 3 supported so as to be swingable by the pivot assembly bearing 10 </ b> A on the magnetic disk 5. Recording is performed, and the recorded information is read from the magnetic disk 5.

  As shown in FIG. 1B, the pivot assembly bearing 10A is inserted into the rolling bearing 30 disposed inside the cylindrical sleeve 20, whereby the sleeve 20 and the shaft 40 shown in FIG. Is a bearing device that enables relative rotation.

  In the pivot assembly bearing 10A, the shaft 40 is fixed to the bottom of the case 6 shown in FIG. 1A, and the sleeve 20 rotates. The sleeve 20 is press-fitted into the mounting hole 2 a of the base 2 of the magnetic head arm 3, and the magnetic head arm 3 swings as the sleeve 20 rotates.

Hereinafter, a pivot assembly bearing 10A according to an embodiment will be described with reference to FIGS.
As shown in FIG. 2, the pivot assembly bearing 10 </ b> A has a shaft 40 with a shaft 40 interposed between a pair of rolling bearings 30 that are spaced apart in the axial direction (left-right direction in FIG. 2) inside a cylindrical sleeve 20. It has a structure that is rotatably supported.

  The rolling bearing 30 is a ball bearing that includes an inner ring 31 and an outer ring 32, and a plurality of spherical rolling elements 33 are held between the inner ring 31 and the outer ring 32. The plurality of rolling elements 33 are held by a retainer (not shown) fitted between the inner ring 31 and the outer ring 32 so as to be rotatable and in a row in the circumferential direction. The inner ring 31 is fixed to the outer peripheral surface 42 of the shaft 40, and the outer ring 32 is fixed to the inner peripheral surface 23 of the sleeve 20. The rolling bearing 30 is fixed to the shaft 40 and the sleeve 20 by means such as adhesion. In the rolling bearing 30, a lubricant such as grease is sealed between the inner ring 31 and the outer ring 32.

  The shaft 40 has a cylindrical shape having a hollow portion 40a at the axis, and a flange portion 41 is formed at the right end in FIG. The flange part 41 has a disk part 41b extending in the radial direction and a cylindrical part 41c protruding in the axial direction from the outer periphery of the disk part 41b. On the end surface of the shaft 40 on the side where the flange portion 41 is formed, an annular convex portion 44 is provided so as to surround the opening of the hollow portion 40a. The outer peripheral surface of the cylindrical portion 41 c of the flange portion 41 faces an annular recess 20 a formed at the end of the inner peripheral surface 23 of the sleeve 20. The inner peripheral surface of the cylindrical portion 41 c of the flange portion 41 faces the outer peripheral surface of the outer ring 32 of the right rolling bearing 30. In FIG. 2, when the inner ring 31 of the left rolling bearing 30 is pushed rightward, the outer ring 32 of the left rolling shaft 30 comes into contact with the spacer portion 21, and the outer ring 32 of the right rolling bearing 30 is interposed via the spacer portion 21. push. Then, the inner ring 31 of the right rolling bearing 30 abuts against the inner surface of the flange portion 41, so that both of the rolling bearings 30 are preloaded.

  As shown in FIG. 3, a labyrinth gap 63 is formed between the outer peripheral surface of the flange portion 41 and the inner peripheral surface of the annular recess 20 a of the sleeve 20, and the end surface of the outer ring 32 of the right rolling bearing 30 and the flange portion 41. A labyrinth gap 63 a is formed between the outer circumferential surface of the outer ring 32 and an inner circumferential surface of the cylindrical portion 41 c of the flange portion 41. Thereby, the labyrinth gap of a longer distance than before is obtained.

  As shown in FIG. 2, a spacer portion 21 having a smaller inner diameter than both end portions is formed concentrically at the axially intermediate portion of the inner peripheral surface 23 of the sleeve 20. As shown in FIG. 4, the stepped surface of the spacer portion 21 is formed with a positioning portion 21 a that is orthogonal to the inner peripheral surface 23 of the sleeve 20 and an inclined relief portion 21 b that is notched inward in the axial direction from the positioning portion 21 a. Has been. The two rolling bearings 30 are axially positioned by bringing the outer ring 32 into contact with the positioning portion 21a. The inner ring 31 and the outer ring 32 are fixed to the outer peripheral surface of the shaft 40 and the inner peripheral surface 23 of the sleeve 20 by means of adhesion or the like in such a state that the preload is applied.

  An annular seal plate (first seal member) 50 is disposed in the left end of the pivot assembly bearing 10A in FIG. The seal plate 50 is disposed to close the gap between the sleeve 20 and the shaft 40, and the outer peripheral surface 52 is fixed to the inner peripheral surface 23 of the sleeve 20 by means such as adhesion.

  As shown in FIG. 5, at the left end of the pivot assembly bearing 10A in FIG. 2, the end surface 31a of the inner ring 31 of the left rolling bearing 30 is axially inward of the end surface 32a of the outer ring 32 (right side in FIG. 5). Is located. The seal plate 50 is in contact with the end surface 32a of the outer ring 32, the first labyrinth gap 61 is formed between the end surface 31a of the inner ring 31 and the annular inner peripheral surface (annular) of the seal plate 50. Surface) 53 and the shaft 40, a second labyrinth gap (seal gap) 62 is formed.

  In order to obtain the above-described structure, as described above, preload is applied to the inner ring 31 toward the inner side in the axial direction, and the inner ring 31 is fixed to the shaft 40 in this state. As a result, as shown in FIG. 5, the end surface 32a of the outer ring 32 is positioned on the axially outer side (left side in FIG. 5) from the end surface 31a of the inner ring 31 by an amount corresponding to the axial gap. Then, the seal plate 50 is brought into contact with the end surface 32 a of the outer ring 32 and the outer ring 32 and the seal plate 50 are fixed to the inner peripheral surface 23 of the sleeve 20, whereby the first between the seal plate 50 and the end surface 31 a of the inner ring 31. The labyrinth gap 61 is formed. By bringing the seal plate 50 into contact with the end surface 32a of the outer ring 32 positioned on the outer side in the axial direction from the end surface 31a of the inner ring 31, the first labyrinth gap can be easily used as the seal plate 50 by using a flat disk without a step. 61 can be formed. Therefore, the seal plate 50 can be manufactured at a low cost by pressing or the like. An annular second labyrinth gap 62 is formed between the seal plate 50 and the shaft 40. The second labyrinth gap 62 can be formed by making the inner diameter dimension of the seal plate 50 slightly larger than the outer diameter dimension of the shaft 40. However, the second labyrinth gap 62 can hold the lubricating fluid by capillary action. It is adjusted so that it may become the clearance gap size.

  As shown in FIG. 5, the inner peripheral surface 53 of the seal plate 50 that forms the second labyrinth gap 62 facing the outer peripheral surface 42 of the shaft 40 is formed in a cylindrical shape. And the end surfaces 54 on both sides are respectively formed with tapered surfaces 55 that gradually move away from the shaft 40 as they move away from the inner peripheral surface 53 in the axial direction. Therefore, the second labyrinth gap 62 is formed in a tapered shape so that both ends gradually expand.

  The fluid seal 70 is provided by holding the lubricating fluid over the entire circumference of the annular second labyrinth gap 62. In the present specification, the fluid seal 70 holds the lubricating fluid over the entire circumference of the annular second labyrinth gap 62 formed by the seal plate 50 and seals the second labyrinth gap 62. Means a seal structure. The fluid seal 70 can fill the second labyrinth gap 62 with liquid oil as a lubricating fluid to form an oil film having an appropriate thickness by capillary action, and seal the gap with the oil film. The oil constituting the fluid seal 70 may be of any type as long as it has a viscosity that can be held in the second labyrinth gap 62 by capillarity, but the base of grease sealed between the inner ring 31 and the outer ring 32 may be used. Use of the same type of oil as oil is preferred because it does not adversely affect the grease. As the base oil, for example, ester oil, mineral oil, synthetic oil or the like can be used.

  In FIG. 5, a seal gap (second labyrinth gap 62) is formed between the seal plate 50 and the outer peripheral surface 42 of the shaft 40, but the present invention is not on the shaft 40 side but on the sleeve 20. Also included is a form in which a seal gap is formed on the inner peripheral surface 23 side and a fluid seal is provided by retaining a lubricating fluid in the gap. In that case, the sealing plate 50 is configured to contact the end surface 31 a of the inner ring 31 without contacting the end surface 32 a of the outer ring 32.

[2] Effects of one embodiment In the pivot assembly bearing 10A described above, the seal plate is free from dust generated due to leakage or evaporation of lubricating oil (base oil) contained in the grease filled therein or from the outside. The left end portion where 50 is disposed is restrained by the seal plate 50, while the right end portion where the flange portion 41 is formed is restrained by the flange portion 41. Further, since the minute labyrinth gaps 61, 62, 63, 63a, and 63b are formed, dust and foreign matters are less likely to pass through these labyrinth gaps 61, 62, 63, 63a, and 63b, and dust generation and foreign matter contamination is prevented. Effectively suppressed.

  In particular, since a fluid seal 70 in which oil is filled in the second labyrinth gap 62 is provided at the left end portion where the seal plate 50 is disposed, dust and foreign matter are placed in the second labyrinth gap 62. Passing through is completely prevented. In addition, the fluid seal 70 has a lower material cost and fewer parts than the magnetic fluid seal. For this reason, it is more advantageous than the magnetic fluid seal in terms of cost and ease of assembly.

  Further, tapered surfaces 55 are formed at both ends in the axial direction (width direction) of the inner peripheral surface 53 of the seal plate 50, and the second labyrinth gap 62 is formed in a tapered shape so that both ends gradually spread. Therefore, when the oil in the fluid seal 70 reaches the tapered portions at both ends of the second labyrinth gap 62, the oil is drawn toward the axial center of the annular second labyrinth gap 62 due to capillary action. For this reason, loss of oil in the fluid seal 70 is suppressed, and oil is always present in the center portion of the second labyrinth gap 62. That is, the fluid seal 70 can exhibit a more stable sealing function.

[3] Other Embodiments Next, with reference to FIGS. 6 and 7, a pivot assembly bearing 10 </ b> B according to another embodiment having a configuration similar to the above-described embodiment will be described. In the reference drawing, the same reference numerals are given to the same components as those of the above-described embodiment, and the description thereof is omitted.

  In the pivot assembly bearing 10B according to another embodiment, the flange portion 41 is not formed on the shaft 40. A seal plate 50 fixed to the inner peripheral surface 23 of the sleeve 20 and an annular outer seal plate (second seal member) 51 positioned outside the seal plate 50 are disposed at both ends of the shaft 40. Has been. The outer seal plates 51 are respectively fixed to the shaft 40 by being press-fitted or bonded to the step portions 43 formed at both ends of the shaft 40, and face the inner peripheral surface of the sleeve 20. As shown in FIG. 7, a gap 64 and a gap 65 are formed between the outer seal plate 51 and the inner peripheral surface of the sleeve 20 and between the outer seal plate 51 and the seal plate 50, respectively. Thus, in the pivot assembly bearing 10B of another embodiment, the same labyrinth structure is formed at both ends.

  As shown in FIG. 7, at both ends of the pivot assembly bearing 10B, the seal plate 50 is in contact with the end surface 32a of the outer ring 32, and the first labyrinth gap is between the seal plate 50 and the end surface 31a of the inner ring 31. 61 is formed, and an annular second labyrinth gap 62 is formed between the seal plate 50 and the shaft 40. The second labyrinth gap 62 is filled with oil and provided with a fluid seal 70 as in the above embodiment.

  In this pivot assembly bearing 10B, the fluid seals 70 are provided at both ends, so that dust generation and foreign matter mixing can be prevented sufficiently and stably. Further, since the capillary seal is constituted by the taper surface 55 of the seal plate 50, oil loss of the fluid seal 70 is prevented.

  Furthermore, since the outer seal plate 51 is disposed outside the seal plate 50, a further effect of preventing dust generation and mixing of foreign matters is exhibited. Further, the outer seal plate 51 prevents the oil in the fluid seal 70 from leaking out due to the air flow.

  The hard disk drive device 1 shown in FIG. 1 in which the magnetic head arm 3 is swingably supported by the pivot assembly bearing 10A according to the above embodiment can maintain the cleanliness of the inside, and thus the reliability of the device is improved. Can be increased. Of course, the same effect can be obtained by using the pivot assembly bearing 10B instead of the pivot assembly bearing 10A.

[4] Shape of an annular surface facing the seal gap of the first seal member In the above embodiment, the seal plate 50 constitutes the first seal member of the present invention. The annular surface (the inner peripheral surface 53) facing the annular seal gap (the second labyrinth gap 62) is shaped so that at least the annular seal gap does not expand toward the axial center of the annular surface. If formed, the capillary force acts toward the center of the annular seal gap, which is effective in preventing the oil filled in the seal gap from flowing out.

  In FIG. 8, in the above embodiment, the inner peripheral surface 53 facing the second labyrinth gap 62 of the seal plate 50 does not widen at least the second labyrinth gap 62 toward the axial center of the inner peripheral surface 53. Although various form examples formed in this way are shown, the present invention is not limited to these form examples.

  FIG. 8A shows a form in which tapered surfaces 55 are formed on both sides of the cylindrical inner peripheral surface 53, that is, at each corner between the inner peripheral surface 53 and both end surfaces 54, respectively. . FIG. 8B shows a configuration in which the region of the tapered surface 55 is larger, and the cylindrical surface is located in the central portion in the axial direction. FIG. 8C shows a form in which the inner peripheral surface 53 is formed in a convex cross section (triangular shape) toward the axially central portion. FIG. 8D shows a form in which the inner peripheral surface 53 is formed in a convex cross-sectional arc shape toward the second labyrinth gap 62. In any case, the fluid seal 70 is formed by filling the second labyrinth gap 62 with oil.

  The present invention can be applied to a pivot assembly bearing for swingably supporting a magnetic head arm in a magnetic disk drive or the like, and is particularly suitable for a server hard disk drive.

  DESCRIPTION OF SYMBOLS 1 ... Hard disk drive device, 3 ... Magnetic head arm, 4 ... Magnetic head, 5 ... Magnetic disk, 10A, 10B ... Pivot assembly bearing, 20 ... Sleeve, 30 ... Rolling bearing, 31 ... Inner ring, 32 ... Outer ring, 33 ... Roll Moving body, 40 ... shaft, 50 ... seal plate (first seal member), 51 ... outer seal plate (second seal member), 53 ... inner peripheral surface (annular surface), 54 ... end surface, 55 ... tapered surface, 61 ... 1st labyrinth gap, 62 ... 2nd labyrinth gap (seal gap), 70 ... Fluid seal.

Claims (6)

Sleeve,
A shaft,
A rolling bearing disposed between the sleeve and the shaft;
A first seal member disposed on the outer side in the axial direction of the rolling bearing,
The lubricating fluid is held over the entire circumference of an annular seal gap formed between the first seal member and the sleeve or between the first seal member and the shaft. Pivot assembly bearing.   The annular surface facing the annular seal gap in the first seal member is formed so that at least the annular seal gap does not expand toward the axial center of the annular surface. The pivot assembly bearing according to Item 1.   The pivot assembly bearing according to claim 2, wherein the annular surface is formed in a cross-sectional convex shape toward an axially central portion of the annular surface.   The pivot assembly bearing according to any one of claims 1 to 3, wherein a corner portion between the end surface of the first seal member and the annular surface is formed in a tapered shape.   The pivot assembly bearing according to any one of claims 1 to 4, wherein a second seal member that covers the seal gap is provided on an outer side in the axial direction of the first seal member.   6. A disk drive apparatus comprising the pivot assembly bearing according to claim 1, wherein a magnetic head arm for moving the magnetic head on the magnetic disk is supported to be swingable.

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