JP2006057812A - Sliding bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding bearing device capable of easily installing a bearing sleeve in a housing without impairing the roundness of a bearing surface. <P>SOLUTION: The bearing sleeve 2 having wedge-shaped flange parts 2d of the number same as projections 3d, 3d, respectively engaged between the projection 3d and a housing bottom part 3b, is fitted to an inner periphery of the housing 3 provided with three or more projections 3d, 3d formed on positions at an axial distance from the bottom part 3b at equal intervals in the circumferential direction, and the flange parts 3d are respectively rotated in the direction to be engaged between the projection 3d and the bottom part 3b, thus the bearing sleeve 2 can be easily and surely fixed to the housing 3 without impairing the roundness of a sleeve inner peripheral face 2b (bearing surface). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sliding bearing device in which a bearing sleeve is housed in a housing, and more particularly to a small and lightweight sliding bearing device suitable for supporting a shaft rotating at high speed, such as a dynamic pressure bearing used in a hard disk drive. .

  2. Description of the Related Art Conventionally, a dynamic pressure type sliding bearing device (dynamic pressure bearing or fluid bearing) used for a spindle motor or a fan motor used in a hard disk drive mainly includes a shaft member made of stainless steel and a bearing sleeve made of metal (alloy). Is used. In addition, along with the recent price reduction of computers, bearing devices are also required to be reduced in cost. As a bearing sleeve, a synthetic resin bearing sleeve that is easy to shape and low in material cost is also used. Being started.

  These bearing sleeves are usually fixed in a bottomed cylindrical housing, and support the rotation of a shaft member arranged with a slight clearance on the inner periphery thereof. Further, as a method for fixing the bearing sleeve at that time, press-fitting or adhesion is used.

  Press fitting is the most common sleeve fixing method in a plain bearing without a dynamic pressure groove. However, in the press-fitting method, there is a “tightening” between the inner diameter of the housing and the outer diameter of the bearing sleeve, so that the bearing surface (sleeve inner peripheral surface) is partially deformed. The degree may not be secured sufficiently. In particular, in a dynamic pressure type sliding bearing device having a dynamic pressure groove on the bearing surface, the bearing sleeve and the shaft member come into contact with each other, or the bearing clearance between the sleeve and the shaft member becomes too large. There was a fear that it could not be fully demonstrated.

  Therefore, a fixing method has been proposed in which a large-diameter fixing portion is provided in the bearing sleeve, and only the fixing portion is involved in press-fitting so that the bearing portion requiring dimensional accuracy does not directly contact the housing (for example, a patent). (See Reference 1, etc.) The present applicants also provide a method of interposing a cushioning member that does not substantially distort the bearing sleeve between the sleeve and the housing, and a cylindrical portion integrally formed on the outside of the bearing sleeve. A fixing method for press-fitting into a housing has been proposed (see Patent Document 2).

  On the other hand, in the method of fixing the bearing sleeve to the housing by bonding, the fit between the sleeve and the housing becomes a clearance fit, and the housing does not press the bearing sleeve, so the sleeve does not deform. Therefore, the above-described problem of roundness of the bearing surface (inner circumferential surface of the bearing sleeve) is solved (see Patent Document 3 and the like).

JP 2001-248644 A JP 2001-165150 A JP 2000-320542 A

  However, the method of fixing the bearing sleeve to the housing by bonding inevitably increases the cost due to an increase in operations such as an adhesive application process and a heat drying process, and also requires careful handling of the adhesive. In particular, in the case of a resin bearing sleeve, the linear expansion coefficient of a so-called super engineering plastic such as polyphenylene sulfide (PPS), thermosetting phenol resin, etc. is used to avoid fluctuations in the bearing clearance due to temperature rise that occurs during bearing rotation. Although a resin material close to the linear expansion coefficient of the metal (stainless steel or the like) forming the member is used, there is a problem that it is difficult to obtain adhesive strength because it is a resin.

  In addition, as the entire spindle including this plain bearing device is required to be smaller and lighter, the various bearing sleeve fixing methods using press-fitting described above handle parts that are becoming smaller in size (such as handling and assembly work). ) Is not easy, and the cost increases due to the complicated shape of the parts including the sleeve or the increase in the number of parts.

  The present invention has been made to address the above-described problems, and an object of the present invention is to provide a plain bearing device in which a bearing sleeve can be easily assembled to a housing without impairing the roundness of the bearing surface. Yes.

  In order to achieve the above object, an invention according to claim 1 includes a shaft member, a bearing sleeve arranged around the shaft member, and a bottomed cylindrical housing for housing the bearing sleeve. In the sliding bearing device, a substantially cylindrical space is formed in the axial direction between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve, and the housing inner peripheral surface has an axial direction from the bottom thereof. Three or more protrusions that are equally spaced in the circumferential direction are provided at spaced positions, and the housing sleeve side end portion of the bearing sleeve is engaged between the protrusion and the housing bottom part. The number of flange portions having a wedge-shaped cross section is the same as the number of these protrusions.

  That is, according to the invention of claim 1, these protrusions are engaged with the inner periphery of the housing provided with three or more protrusions that are equally spaced in the circumferential direction at positions spaced apart from the bottom in the axial direction. By inserting a bearing sleeve having the same number of wedge-shaped flange portions and rotating the bearing sleeve in a direction in which the flange portion is engaged between the protrusion and the bottom portion, a perfect circle on the inner peripheral surface (bearing surface) of the sleeve is obtained. The bearing sleeve can be fixed to the housing without deteriorating the degree.

  In addition, this sleeve fixing method can easily fix the bearing sleeve without increasing the number of parts and labor in the process, and is substantially cylindrical between the outer peripheral surface of the bearing sleeve and the inner peripheral surface of the housing. By forming the gap of the shape, the movable range on the other end side where the flange portion is not formed in the bearing sleeve is expanded. Therefore, this bearing sleeve comes to follow (that is, alignability) with respect to the displacement and swinging of the rotating shaft of the shaft member.

  Next, in order to achieve the same object, the invention described in claim 2 includes a shaft member, a bearing sleeve arranged around the shaft member, and a bottomed cylindrical housing that houses the bearing sleeve. In the slide bearing device comprising: a substantially cylindrical space is formed in the axial direction between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve, and in the substantially cylindrical space The cylindrical body has an inner diameter larger than the outer peripheral surface of the bearing sleeve and an outer diameter larger than the inner peripheral surface of the housing, and a cylindrical body that presses the bearing sleeve toward the bottom of the housing is press-fitted and fixed. And

  According to the above configuration, the outer peripheral surface of the cylindrical body is press-fitted into the inner periphery of the housing. However, the inner surface of the cylindrical body and the outer peripheral surface of the bearing sleeve are similar to those in the first aspect. A substantially cylindrical clearance is formed, and this bearing sleeve can be fixed to the housing without impairing the roundness of the inner circumferential surface (bearing surface) of the sleeve.

  Here, as a material for forming the cylindrical body, a sintered material is preferable (Claim 3). This is because the surface roughness due to the particles (sintered material) constituting the cylindrical body becomes an anchor for the inner peripheral surface of the housing or the bearing sleeve. With this action, a sufficient fixing / rotation preventing effect can be obtained. Can do. Further, since the sintered material absorbs excess lubricant and the like leaking from the sliding bearing surface, it has an effect of preventing contamination by oil around the bearing device.

  In addition, as a shape of the cylindrical body, a flange portion protruding radially inward is formed at one axial end portion, and the housing opening side end portion of the bearing sleeve is pressed toward the housing bottom portion by the flange portion. (Claim 4).

  With this configuration, the bearing sleeve does not need to have a complicated shape, and an increase in the processing cost of the bearing sleeve can be suppressed. However, the inner diameter of this cylindrical body needs to be formed larger than the outer diameter of the bearing sleeve, and due to this shape, between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the bearing sleeve, the same as described above. A substantially cylindrical clearance is formed.

  If a dynamic pressure generating groove is formed on either the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member, the shaft member can be rotated in a non-contact manner as a dynamic pressure type slide bearing (dynamic pressure bearing) device. (Claim 5).

  As described above in detail, according to the sliding bearing device of the present invention, since the cylindrical portion of the bearing sleeve is not directly press-fitted into the housing, the roundness of the inner peripheral surface of the sleeve is maintained. In addition, this sliding bearing device requires less labor when assembling the bearing, and can suppress an increase in cost to a minimum.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is an axial sectional view showing the structure of a plain bearing device according to a first embodiment of the present invention. FIG. 2 is an explanatory view for explaining a fixing method of the bearing sleeve in the sliding bearing device, and FIG. 3 is an external perspective view of the bearing sleeve used in the sliding bearing device.

  The slide bearing device according to the present embodiment is a hydrodynamic slide bearing of a type in which a load in the radial direction is applied by dynamic pressure generated by a pumping action of a dynamic pressure generating groove. A bearing sleeve 2 (hereinafter simply referred to as “sleeve”) disposed around is mainly used. The shaft 1 and the sleeve 2 are accommodated in a bottomed cylindrical housing 3.

  The shaft 1 is made of, for example, stainless steel, and is configured as a pivot bearing that applies a load in the axial (thrust) direction by an end portion 1a formed in a hemispherical shape. The sleeve 2 is formed by injection molding a resin material or the like, and has a cylindrical portion 2a and a flange portion 2d formed so as to protrude radially outward from one end (the lower end portion in the drawing). It consists of. The diameter of the inner peripheral surface 2b of the cylindrical portion 2a is formed to be slightly larger than the outer diameter of the shaft 1 to be fitted, and at a position spaced apart in the axial direction of the inner peripheral surface 2b, 2 is provided. Two radial dynamic pressure grooves 2v, 2v are formed.

  The housing 3 includes a cylindrical portion 3a for housing the shaft 1 and the sleeve 2 and a bottom portion 3b. The sleeve 2 has a flange portion 2d at the bottom portion 3b on the inner periphery (non-through hole) of the cylindrical portion 3a. A substantially cylindrical space (gap S) is formed in the axial direction between the outer peripheral surface 2 c of the sleeve 2 and the inner peripheral surface 3 c of the housing 3. The space between the shaft 1 and the sleeve 2 is filled with a lubricating fluid (lubricant) (not shown), and the opening of the housing 3 is sealed by a lid member or a capillary seal. Further, the rotation of the shaft 1 is supported in a non-contact manner by the dynamic pressure generated in the lubricating fluid by the relative rotation between the shaft 1 and the sleeve 2.

  A feature of the plain bearing device in the present embodiment is a fixing method of the sleeve 2. As shown in FIG. 3, four flange portions 2d, 2d,... Having a wedge-shaped cross section in the circumferential direction are provided at the end portion of the sleeve 2 on the housing bottom 3b side. The four projections 3d, 3d,..., Which are equally spaced in the circumferential direction, are formed on the inner circumferential surface 3c of the housing cylindrical portion 3a at positions spaced apart from the bottom 3b in the axial direction. Is provided. Therefore, as shown in FIG. 2, the sleeve 2 is fitted into the inner periphery of the housing 3 with the phase of each flange portion 2d shifted from the projection 3d, and the wedge-shaped flange portion 2d is connected to the projection 3d and the housing bottom portion 3b. Can be easily and reliably fixed by rotating in a direction (arrow A direction).

  With the above configuration, the plain bearing device of the present embodiment can fix the bearing sleeve 2 to the housing 3 without impairing the roundness of the sleeve inner peripheral surface 2b (bearing surface). Problems caused by partial deformation can be prevented.

  In addition, since this plain bearing device can position the flange 2d of the sleeve 2 on the bottom 3b of the housing 3 and position the sleeve 2 by rotating it in a predetermined direction, it can be fixed with little effort in the process. Without increasing, it is possible to minimize the increase in cost.

  By providing a clearance S between the sleeve 2 and the housing 3, the other end (the upper side in the figure) of the sleeve 2 where the flange portion 2d is not formed is displaced or swung around the rotation axis of the shaft 1. It becomes possible to follow.

Next, a second embodiment of the present invention will be described.
FIG. 4 is an axial sectional view showing the structure of the plain bearing device in the second embodiment of the present invention.

  The basic structure of the plain bearing device according to this embodiment is the same as that of the first embodiment, and is mainly composed of a cylindrical shaft 1 made of stainless steel and a resin sleeve 12 arranged around the shaft 1. It is configured as. The shaft 1 and the sleeve 12 are accommodated in a bottomed cylindrical housing 3.

  The sleeve 12 is formed by injection molding of a resin material. Like the first embodiment, the sleeve 12 has two radial dynamic pressure grooves at a position spaced apart in the axial direction of the inner peripheral surface 12a. 12v and 12v are formed.

  The feature of the plain bearing device in the present embodiment is that the sleeve 12 is fixed by a cylindrical body 4 disposed inside the cylindrical portion 3 a of the housing 3. The cylindrical body 4 is formed by sintering using a metal material. Since the inner peripheral surface 4a has a larger diameter than the outer diameter of the sleeve 12, the cylindrical body 4 is interposed between the sleeve 12 and the outer peripheral surface 12b. A substantially cylindrical space (gap S) is formed.

  The cylindrical body 4 is formed such that the outer peripheral surface 4b has a diameter larger than the diameter of the housing inner peripheral surface 3c, and the outer periphery is press-fitted and fixed to the inner periphery of the housing cylindrical portion 3a. The housing opening side end portion 12c of the sleeve 12 is pressed toward the housing bottom 3b side by a flange portion 4d formed on the housing opening side end portion 4c inward in the radial direction.

  With the above-described configuration, the roundness of the sleeve inner peripheral surface (bearing surface) 12a is also maintained in the sliding bearing device according to the present embodiment without pressing the cylindrical portion 12a of the sleeve 12 directly into the housing 3. In addition, the sleeve 12 in the present embodiment is not complicated, and can be fixed by simply placing the sleeve 12 on the bottom 3b of the housing 3 and fitting the cylindrical body 4 therewith. Without increasing, it is possible to minimize the increase in cost.

  In addition, the cylindrical body 4 of the slide bearing device according to the present embodiment can obtain a sufficient fixing / rotation preventing effect due to the rough surface due to the sintered material to be formed, and an extra portion leaked from the slide bearing surface. Since the lubricant and the like are absorbed, there is an effect of preventing contamination by oil around the bearing device.

  In the above-described two embodiments, the resin bearing sleeve has been described as an example. However, the material of the bearing sleeve in the present invention is not limited to resin, but may be a metal used for a general slide bearing or the like. But it ’s okay. However, in order to avoid fluctuations in the bearing clearance due to temperature rise that occurs when the bearing rotates, a resin material whose linear expansion coefficient is close to the linear expansion coefficient of the metal (stainless steel or the like) forming the shaft is preferable. Examples include super engineering plastics such as polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyamide imide (PAI), polyether imide (PEI), thermosetting phenol resins and epoxy resins, or the like. And resin materials in which reinforcing fibers are mixed.

  The means for forming a bearing sleeve using these resin materials is not limited to injection molding, and may be appropriately selected according to the dimensions of the bearing sleeve, the properties of the material, and the like. It may be formed on either the peripheral surface or the outer peripheral surface of the opposing shaft.

It is an axial sectional view showing the structure of the plain bearing device in the first embodiment of the present invention. It is explanatory drawing explaining the fixing method of the bearing sleeve in the slide bearing apparatus of 1st Embodiment of this invention. It is an external appearance perspective view of the bearing sleeve used for the sliding bearing apparatus of 1st Embodiment of this invention. It is an axial sectional view showing the structure of the plain bearing device in the second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 1a End part 2 Sleeve 2a Cylindrical part 2b Inner peripheral surface 2c Outer peripheral surface 2d Flange part 3 Housing 3a Cylindrical part 3b Bottom part 3c Inner peripheral surface 4 Cylindrical body 4a Inner peripheral surface 4b Outer peripheral surface 4c End part 4d Ridge part 12 Sleeve 12a Inner peripheral surface 12b Outer peripheral surface 12c End

Claims (5)

In a plain bearing device comprising a shaft member, a bearing sleeve arranged around the shaft member, and a bottomed cylindrical housing that houses the bearing sleeve,
A substantially cylindrical space is formed in the axial direction between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve, and the housing inner peripheral surface is positioned at a distance from the bottom in the axial direction. Further, three or more protrusions that are equally distributed in the circumferential direction are provided, and a wedge-shaped cross-section that engages between the protrusion and the housing bottom portion at the housing bottom side end portion of the bearing sleeve. The slide bearing device is characterized in that the same number of flange portions as the protrusions are formed. In a plain bearing device comprising a shaft member, a bearing sleeve arranged around the shaft member, and a bottomed cylindrical housing that houses the bearing sleeve,
A substantially cylindrical space is formed in the axial direction between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve, and the outer peripheral surface of the bearing sleeve is formed in the substantially cylindrical space. A sliding bearing device having a larger inner diameter and an outer diameter larger than the inner peripheral surface of the housing, and a cylindrical body that presses the bearing sleeve toward the bottom of the housing is press-fitted and fixed.   The plain bearing device according to claim 2, wherein the cylindrical body is formed using a sintered material.   A flange portion protruding radially inward is formed at one axial end portion of the cylindrical body, and the cylindrical body has the housing opening side end portion of the bearing sleeve on the bottom side by the flange portion. The sliding bearing device according to claim 2 or 3, wherein the sliding bearing device is pressed. The sliding bearing device according to any one of claims 1 to 4, wherein a dynamic pressure generating groove is formed on either the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member. .

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