JP5020652B2 - Hydrodynamic bearing device - Google Patents

Description

  The present invention relates to a hydrodynamic bearing device.

  The hydrodynamic bearing device is a bearing device that rotatably supports a shaft member with an oil film formed in a bearing gap. This hydrodynamic bearing device has characteristics such as high-speed rotation, high rotation accuracy, and low noise. In recent years, the hydrodynamic bearing device has been utilized as a motor bearing device for motors mounted on various electrical devices including information devices. More specifically, magnetic disk devices such as HDDs, optical disk devices such as CD-ROM, CD-R / RW, DVD-ROM / RAM, spindle motors such as magneto-optical disk devices such as MD and MO, laser beams, etc. It is suitably used as a bearing device for a motor such as a polygon scanner motor or a fan motor of a printer (LBP).

As a fluid dynamic bearing device incorporated in a spindle motor such as a disk device, for example, a configuration shown in FIG. 7 is known. In the hydrodynamic bearing device 71 shown in the figure, a bearing sleeve 78 is fixed to the inner periphery of a resin housing 77 integrally having a side portion and a bottom portion, and a shaft member 72 is inserted into the inner periphery of the bearing sleeve 78. . When the shaft member 72 rotates, radial bearing portions 75 and 76 that support the shaft member 72 in the radial direction are formed in a radial bearing gap between the outer peripheral surface of the shaft member 72 and the inner peripheral surface of the bearing sleeve 78. (For example, see Patent Document 1).
JP 2005-28279 A

  By the way, in the above-described hydrodynamic bearing device for a spindle motor, an axial load may be applied to the bottom of the housing via the shaft member when a disk hub is fixed to the shaft member or when an impact is applied during bearing operation. is there. The bottomed cylindrical resin housing is advantageous for cost reduction compared to the case where the housing is a metal machined product, but the bottom portion is deformed when a load is applied, and the rotational accuracy in the thrust direction is lowered. There is a high risk. In particular, when the load is excessive, the connecting portion between the bottom and the side may break and the bottom may fall off. With the increase in capacity of disk devices in recent years, the number of disks mounted on disk hubs has increased (multi-layered disks), and the load applied to the bottom tends to increase, and the above problems are likely to occur. It has become.

  An object of the present invention is to provide a hydrodynamic bearing device that increases the strength of the bottom of a bottomed cylindrical resin housing and boasts high rotational accuracy.

In order to solve the above problem, the present invention, have a side and bottom together, and a housing made of resin that will be fixed to the inner periphery of the bracket, fixed to the inner periphery of the housing, one end surface is first thrust In a hydrodynamic bearing device comprising a bearing sleeve facing a bearing gap and a radial bearing portion for supporting in a radial direction a shaft to be supported by an oil film generated in a radial bearing gap facing the inner circumferential surface of the bearing sleeve , a bracket is provided on the outer circumferential surface. Ri Do from the axial portion and integral therewith in the radial portion having a fixing surface for the axial portion is more provided with metal reinforcing member in the circumferential direction is arranged on the bottom side corner portions of the housing, the housing, Provided is a fluid dynamic bearing device which is injection-molded with a reinforcing member as an insert part .

  As described above, by arranging the reinforcing member including the axial portion and the radial portion at the bottom corner portion of the housing, the connecting portion (connecting portion) between the side portion and the bottom portion in the bottomed cylindrical resin housing. Can be reinforced. Therefore, the strength of the bottom of the housing can be increased, and it is possible to prevent the bottom from being deformed when an axial load is applied, and further to prevent the bottom from falling off. In particular, when the reinforcing member is made of metal and disposed on the outer surface side of the housing, part or all of the outer surface of the housing is replaced with the metal surface. The fixing strength of the both can be increased without elaborating a different device (for example, surface modification treatment) for improving the adhesive strength on the outer peripheral surface of the resin housing to be fixed or the inner peripheral surface of the motor bracket.

  The axial portion of the reinforcing member can be provided at a plurality of locations in the circumferential direction, that is, intermittently provided in the circumferential direction. For example, when a metal axial part is provided continuously in the circumferential direction (when the axial part is cylindrical), the resin generally has a sufficiently large coefficient of linear expansion compared to that of metal. If the housing thermally expands with this temperature change, the expansion cannot be released to the outer diameter side, and the width accuracy of the radial bearing gap, that is, the rotational accuracy of the radial bearing portion may be adversely affected. On the other hand, if the axial portions are provided at a plurality of locations in the circumferential direction as described above, the rigidity in the radial direction of the reinforcing member is relaxed, which adversely affects the width accuracy of the radial bearing gap and causes rotation in the radial direction. It is possible to avoid a decrease in accuracy.

  As described above, the deformation and breakage of the housing bottom portion when a load is applied are most likely to occur at the connecting portion between the side portion and the bottom portion. Therefore, it is desirable that the radial direction portion of the reinforcing member extends to the inner diameter side to a position exceeding the inner peripheral surface of the side portion of the housing. From the same viewpoint, it is desirable that the axial portion of the reinforcing member is provided so as to extend to a position exceeding the bottom inner bottom surface of the housing.

  In the above configuration, the housing can be injection-molded using the reinforcing member as an insert part. With such a configuration, the molding of the housing and the assembly of the reinforcing member can be performed in one step, so that the trouble of assembling the reinforcing member to the housing can be saved, and the cost increase due to the provision of the reinforcing member can be suppressed as much as possible can do.

  The reinforcing member can be arranged on the outer surface side of the housing as described above. However, from the viewpoint of increasing the strength of the bottom of the housing, the reinforcing member is not necessarily arranged on the outer surface side of the housing. It can be arranged on the inner surface side or can be arranged inside the housing (embedded in the housing).

  As described above, according to the present invention, the strength of the resin-made housing bottom can be increased, and a situation in which the rotational accuracy of the thrust bearing portion, which is a concern when a load is applied, can be avoided, and further, the situation where rotation is impossible can be avoided. . Therefore, it is possible to provide a hydrodynamic bearing device that boasts high rotational accuracy and is highly reliable.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 conceptually shows one configuration example of a spindle motor for information equipment incorporating a fluid dynamic bearing device. This spindle motor is used for a disk drive device such as an HDD, and has a hydrodynamic bearing device 1 that rotatably supports a shaft member 2, a disk hub 3 mounted on the shaft member 2, and a radial gap, for example. And a stator magnet 4 and a rotor magnet 5 which are opposed to each other. The stator coil 4 is attached to the outer periphery of the motor bracket (bracket) 6, and the rotor magnet 5 is attached to the inner periphery of the disk hub 3. The housing 7 of the hydrodynamic bearing device 1 is attached to the inner periphery of the bracket 6. The disk hub 3 holds one or more disks D such as magnetic disks. When the stator coil 4 is energized, the rotor magnet 5 is rotated by the electromagnetic force between the stator coil 4 and the rotor magnet 5, whereby the disk hub 3 and the shaft member 2 are rotated together.

  FIG. 2 is an enlarged cross-sectional view of the hydrodynamic bearing device 1 shown in FIG. 1, and shows a first embodiment of the hydrodynamic bearing device according to the present invention. The hydrodynamic bearing device 1 includes a housing 7 having a side portion and a bottom portion integrally, a bearing sleeve 8 fixed to the inner periphery of the housing 7, a shaft member 2 inserted into the inner periphery of the bearing sleeve 8, and the housing 7. The seal member 9 that seals the opening of the housing 7 and the reinforcing member 12 disposed at the bottom corner portion of the housing 7 are provided as main components. In the following description, for convenience of explanation, the description will proceed with the opening side of the housing 7 as the upper side and the opposite side in the axial direction as the lower side.

  The shaft member 2 is formed of, for example, a metal material such as stainless steel, and includes a shaft portion 2a and a flange portion 2b provided integrally or separately at the lower end of the shaft portion 2a. The shaft member 2 may be entirely formed of a metal material, or may be a hybrid structure of metal and resin, for example, the entire flange portion 2b or a part thereof (for example, both end surfaces) made of resin.

  The bearing sleeve 8 is formed in a cylindrical shape with a porous body made of sintered metal, in particular, a sintered body of sintered metal mainly composed of copper. The bearing sleeve 8 can be formed not only from a sintered metal but also from a soft metal material such as brass, or another porous body (such as a porous resin) that is not a sintered metal.

  The inner peripheral surface 8a of the bearing sleeve 8 is provided with two upper and lower regions (black portions in FIG. 2) which are radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2 and are separated in the axial direction. In the two regions, a plurality of dynamic pressure grooves 8a1 and 8a2 arranged in a herringbone shape as shown in FIG. 3 are formed, for example. The upper dynamic pressure groove 8a1 is formed axially asymmetric with respect to the axial center m (the axial center of the upper and lower inclined groove regions), and the axial dimension X1 of the upper region is lower than the axial center m. It is larger than the axial dimension X2 of the side region. The dynamic pressure groove can also be formed on the outer peripheral surface 2a1 of the shaft portion 2a, and the shape thereof can be other known shapes such as a spiral shape. The outer peripheral surface 8d of the bearing sleeve 8 is formed with one or a plurality of axial grooves 8d1 that allow the both end surfaces 8b and 8c to communicate with each other. In this embodiment, the axial grooves 8d1 are equally distributed at three locations in the circumferential direction. Has been.

  The lower end face 8b of the bearing sleeve 8 is provided with a region (blacked portion in FIG. 2) that becomes the thrust bearing surface of the first thrust bearing portion T1, and this region is omitted in illustration, for example, in a spiral shape. A plurality of arranged dynamic pressure grooves are formed. The dynamic pressure groove may be formed on the upper end surface 2b1 of the flange portion 2b, and the shape thereof may be other known shapes such as a herringbone shape.

  The housing 7 has a bottomed cylindrical shape integrally including a side portion and a bottom portion 7c that seals a lower end opening of the side portion. In this embodiment, the side part is comprised by the cylindrical small diameter part 7a and the cylindrical large diameter part 7b arrange | positioned above the small diameter part 7a. The inner peripheral surface 7a1 and the outer peripheral surface 7a2 of the small diameter portion 7a are formed to have a smaller diameter than the inner peripheral surface 7b1 and the outer peripheral surface 7b2 of the large diameter portion 7b, respectively. The inner peripheral surface 7a1 of the small diameter portion 7a and the inner peripheral surface 7b1 of the large diameter portion 7b are continuous with a step surface 7e formed in a flat surface shape in a direction orthogonal to the axial direction.

  The inner bottom surface 7c1 of the housing 7 is provided with a region (blacked portion in FIG. 2) that becomes a thrust bearing surface of the second thrust bearing portion T2, and this region is not illustrated, but is arranged in a spiral shape, for example. A plurality of dynamic pressure grooves are formed. This dynamic pressure groove can also be formed in the lower end surface 2b2 of the flange portion 2b, and the shape thereof can be other known shapes such as a herringbone shape.

  A reinforcing member 12 having a substantially L-shaped cross section, which is formed of a metal material such as stainless steel and integrally includes an axial direction portion 12a and a radial direction portion 12b, is disposed at the bottom corner portion of the outer surface of the housing 7. . In the present embodiment, the axial portion 12 a of the reinforcing member 12 extends upward to a position exceeding the bottom inner bottom surface 7 c 1 of the housing 7 and further the second radial bearing portion R 2, and the radial portion 12 b is within the small diameter portion of the housing 7. It extends to the inner diameter side up to a position exceeding the peripheral surface 7a1 and further the second thrust bearing portion T2, and a hole is provided at the center thereof. The axial portion 12a is provided at a plurality of locations in the circumferential direction. Therefore, the axial portion 12a of the reinforcing member 12 has an intermittent comb shape in the circumferential direction.

  The housing 7 is injection-molded with resin by inserting the reinforcing member 12 described above. In order to prevent deformation due to the difference in shrinkage during molding shrinkage, the portions 7a to 7c of the housing 7 are formed to have a substantially uniform thickness. Although illustration is omitted, when the housing 7 is injection-molded, the resin filling into the mold is performed, for example, on the outer bottom surface of the bottom portion 7c through a hole formed in the radial portion 12b of the reinforcing member 12. It can be performed from a substantially central portion.

  The resin forming the housing 7 is mainly a thermoplastic resin. For example, as the amorphous resin, polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherimide (PEI) As the crystalline resin, liquid crystal polymer (LCP), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), or the like can be used. The type of filler to be filled in the resin is not particularly limited. For example, as the filler, fibrous filler such as glass fiber, whisker-like filler such as potassium titanate, and scaly filler such as mica. A fibrous or powdery conductive filler such as carbon fiber, carbon black, graphite, carbon nanomaterial, or metal powder can be used. These resins and fillers may be used alone or in combination of two or more.

  The seal member 9 is made of, for example, a soft metal material such as brass, another metal material, or a resin material, and a ring-shaped first seal portion 9a and a cylindrical shape projecting downward from the outer diameter side of the first seal portion 9a. The second seal portion 9b is integrally formed with an inverted L-shaped cross section. A first seal space S1 having a predetermined volume is formed between the inner peripheral surface 9a2 of the first seal portion 9a and the outer peripheral surface 2a1 of the shaft portion 2a. Further, the outer peripheral surface 9 b 1 of the second seal portion 9 b forms a second seal space S 2 having a predetermined volume with the inner peripheral surface 7 b 1 of the large diameter portion 7 b constituting the housing 7. In the present embodiment, the inner peripheral surface 9a2 of the first seal portion 9a and the inner peripheral surface 7b1 of the large-diameter portion 7b of the housing 7 are both formed in a tapered surface shape whose diameter is enlarged upward, and therefore the first and first The two seal spaces S1, S2 have a tapered shape that gradually decreases downward.

  In the lower end surface 9a1 of the first seal portion 9a, one or a plurality of radial grooves 10 crossing the lower end surface 9a1 are formed. Although illustration is omitted, in this embodiment, the radial grooves 10 are equally arranged at three locations in the circumferential direction.

  In the hydrodynamic bearing device 1 composed of the above-described constituent members, the shaft sleeve 2 is accommodated in the housing 7 and the bearing sleeve 8 is fixed to the inner periphery of the housing 7 or the shaft member 2 is inserted in the inner periphery. The bearing sleeve 8 can be assembled by inserting it into the housing 7 and then fixing it, and further fixing the seal member 9 to the bearing sleeve 8. Thereafter, when the internal space of the housing 7 sealed by the seal member 9 is filled with lubricating oil including the internal pores of the bearing sleeve 8, the hydrodynamic bearing device 1 shown in FIG. 2 is completed.

  The housing 7 and the bearing sleeve 8 can be fixed, and the bearing sleeve 8 and the seal member 9 can be fixed by press-fitting or bonding, or press-fitting (press-fitting with an adhesive). After assembly, the lower end surface 9a1 of the first seal portion 9a constituting the seal member 9 contacts the upper end surface 8c of the bearing sleeve 8, and the lower end surface of the second seal portion 9b is in contact with the stepped surface 7e of the housing 7. Opposing via the directional gap 11. Further, the seal member 9 is disposed on the inner diameter side of the large diameter portion 7 b of the housing 7.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the upper and lower two regions serving as the radial bearing surface of the inner peripheral surface 8a of the bearing sleeve 8 are different from the outer peripheral surface 2a1 of the shaft portion 2a. Opposing through the bearing gap. As the shaft member 2 rotates, the oil film formed in each radial bearing gap has its oil film rigidity increased by the dynamic pressure action of the dynamic pressure grooves 8a1 and 8a2 respectively formed on the radial bearing surfaces. Thus, the shaft member 2 is supported in a non-contact manner so as to be rotatable in the radial direction. As a result, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are formed.

  Further, when the shaft member 2 rotates, a region serving as a thrust bearing surface of the lower end surface 8b of the bearing sleeve 8 faces the upper end surface 2b1 of the flange portion 2b via a thrust bearing gap, and the inner bottom surface 7c1 of the housing 7 The region to be the thrust bearing surface is opposed to the lower end surface 2b2 of the flange portion 2b via the thrust bearing gap. As the shaft member 2 rotates, the oil film formed in the thrust bearing gaps has its oil film rigidity increased by the dynamic pressure action of the dynamic pressure grooves formed on the thrust bearing surfaces. 2 is supported in a non-contact manner so as to be rotatable in both thrust directions. Thereby, the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which non-contact-support the shaft member 2 rotatably in both thrust directions are formed.

  Further, when the shaft member 2 is rotated, as described above, the first and second seal spaces S1 and S2 have a tapered shape that is gradually reduced toward the inner side of the housing 7, and thus both the seal spaces S1. The lubricating oil in S2 is drawn toward the direction in which the seal space becomes narrow, that is, toward the inside of the housing 7, by the drawing action by the capillary force. Thereby, the leakage of the lubricating oil from the inside of the housing 7 is effectively prevented. Further, the seal spaces S1 and S2 have a buffer function for absorbing a volume change amount associated with a temperature change of the lubricating oil filled in the internal space of the housing 7, and within the range of the assumed temperature change, The oil level is always in the seal space S1, S2.

  While the inner peripheral surface 9a2 of the first seal portion 9a is a cylindrical surface, a tapered surface may be formed on the outer peripheral surface 2a1 of the shaft portion 2a opposite to the cylindrical surface. In this case, the first seal space S1 is formed in the first seal space S1. Since a function as a centrifugal seal is further added, the sealing effect is further enhanced.

  Further, as described above, the upper dynamic pressure groove 8a1 is formed axially asymmetric with respect to the axial center m, and the axial dimension X1 of the upper region from the axial center m is the axial direction of the lower region. It is larger than the dimension X2 (see FIG. 3). Therefore, when the shaft member 2 rotates, the lubricating oil pulling force (pumping force) by the dynamic pressure groove 8a1 is relatively larger in the upper region than in the lower region. The lubricating oil filled in the gap between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a1 of the shaft portion 2a due to the differential pressure of the pulling force becomes the thrust bearing gap of the first thrust bearing portion T1. The fluid passage formed by the axial groove 8d1 of the bearing sleeve 8 circulates through the path of the fluid passage formed by the radial groove 10 of the first seal portion 9a, and again into the radial bearing gap of the first radial bearing portion R1. Be drawn.

  In this way, by configuring the lubricating oil to flow and circulate in the internal space of the housing 7, the pressure balance of the lubricating oil is maintained, and at the same time, the generation of bubbles accompanying the generation of local negative pressure, Problems such as leakage of lubricating oil and generation of vibration due to generation can be solved. When the first seal space S1 communicates with the circulation path, and the second seal space S2 communicates with the axial clearance 11, the bubbles are mixed into the lubricating oil for some reason. However, when the bubbles circulate with the lubricating oil, the air is discharged from the oil surface (gas-liquid interface) of the lubricating oil in the seal spaces S1 and S2 to the outside air. Therefore, adverse effects due to air bubbles can be more effectively prevented.

  Although not shown, the axial fluid passage is formed by providing axial grooves on the inner peripheral surface 7a1 of the small diameter portion 7a of the housing 7 and the inner peripheral surface 9b2 of the second seal portion 9b of the seal member 9. Alternatively, the radial fluid passage can be formed by providing a radial groove in the upper end surface 8 c of the bearing sleeve 8.

  In the hydrodynamic bearing device 1 described above, the metal reinforcing member 12 composed of the axial portion 12a and the radial portion 12b is disposed at the bottom corner portion of the bottomed cylindrical housing 7 made of resin. The connecting portion between the side portion (small diameter portion 7a) and the bottom portion 7c in the housing 7 can be reinforced. Therefore, the strength of the bottom portion 7c of the housing 7 can be increased, and when the axial load is applied, the bottom portion 7c can be prevented from being deformed and further dropped off. Accordingly, it is possible to prevent the width accuracy of the thrust bearing gap of the second thrust bearing portion T2, that is, the rotational accuracy of the second thrust bearing portion T2, from being lowered, and the function as a bearing can be highly accurate over a long period of time. Can be secured. In particular, in this embodiment, the axial direction portion 12a of the reinforcing member 12 extends upward to a position exceeding the bottom inner bottom surface 7c1 of the housing 7, and the radial direction portion 12b extends to a position exceeding the small diameter inner peripheral surface 7a1 of the housing 7. Since it extends to the inner diameter side, the above-described effects can be enjoyed more effectively.

  Further, with this configuration, the outer peripheral surface 7a2 of the small-diameter portion 7a of the housing 7, that is, a part or all of the fixing surface for the bracket 6 (see FIG. 1) is replaced with a metal surface. Therefore, even when the housing 7 is bonded and fixed to the inner periphery of the bracket 6, the fixing strength of the hydrodynamic bearing device 1 with respect to the motor is not applied to the outer peripheral surface 7 a 2 of the housing 7 or the inner peripheral surface of the bracket 6. (Adhesive strength) can be increased.

  In this embodiment, since the reinforcing member 12 is an insert part of the housing 7, it is possible to suppress the increase in cost due to providing this type of reinforcing member 12 while omitting the trouble of assembling both in a separate process or the like. it can. However, when the reinforcing member 12 is an insert part, the housing 7 and the reinforcing member 12 are in close contact with each other. Therefore, if the axial portion 12a has a cylindrical shape, the resin changes with the temperature change during the bearing operation. When the made housing 7 is thermally expanded, the expansion of the housing 7 cannot be released to the outer diameter side, and the width accuracy of the radial bearing gap may be deteriorated. On the other hand, in this embodiment, since the axial direction part 12a is provided in the multiple places of the circumferential direction, the rigidity of the radial direction of the reinforcement member 12 is relieve | moderated. Accordingly, it is possible to avoid the deterioration of the width accuracy of the radial bearing gap when the housing 7 is thermally expanded, that is, the deterioration of the rotation accuracy in the radial direction.

  Further, in the hydrodynamic bearing device 1 of the present embodiment, a seal space is formed not only on the inner peripheral side of the seal member 9 but also on the outer peripheral side. The seal space has a volume capable of absorbing a volume change amount due to a temperature change of the lubricating oil filled in the internal space of the housing 7, and therefore the second seal space S2 has the configuration of this embodiment. The axial dimension of the first seal space S1 can be made smaller than that of the configuration shown in FIG. Therefore, for example, the hydrodynamic bearing device shown in FIG. 7 shows the axial length of the bearing sleeve 8 without increasing the axial dimension of the bearing device (housing 7), in other words, the bearing span between the radial bearing portions R1 and R2. The moment rigidity can be increased.

  FIG. 4 shows a fluid dynamic bearing device according to a second embodiment of the present invention. The main difference between the hydrodynamic bearing device 21 shown in FIG. 2 and the hydrodynamic bearing device 1 shown in FIG. 2 is that the outer diameter of the side portion of the housing 7 is the same diameter over the entire length in the axial direction. Further, a step portion is integrally provided on the inner periphery of the boundary portion between the side portion of the housing 7 and the bottom portion 7c. The flange portion 2 b of the shaft member 2 is disposed on the inner diameter side of the step portion, and the step portion can be used as a positioning portion for the bearing sleeve 8. Accordingly, the width management of the thrust bearing gap can be easily performed. Since the configuration other than this is in accordance with the embodiment shown in FIG. 2, common reference numerals are given and redundant description is omitted.

  FIG. 5 shows a third embodiment of the hydrodynamic bearing device according to the present invention. 2 is different from the hydrodynamic bearing device 1 shown in FIG. 2 in that the reinforcing member 12 is an insert part of the housing 7 in the embodiment shown in FIGS. The reinforcing member 12 is bonded to the outer diameter side of the housing 7 with a gap. Since the configuration other than this is in accordance with the embodiment shown in FIG. 2, common reference numerals are given and redundant description is omitted.

  In the configuration shown in FIG. 5 as well, the axial portion 12 a of the reinforcing member 12 has a comb shape in which a plurality of the axial portions 12 a are provided in the circumferential direction. When bonding, the axial direction part 12a can also be made into a cylindrical shape. This is because the expansion amount of the housing 7 due to the temperature change during the bearing operation can be absorbed by the adhesive gap between the housing 7 and the reinforcing member 12.

  FIG. 6A shows a fourth embodiment of the hydrodynamic bearing device according to the present invention. The main difference of the hydrodynamic bearing device 41 shown in the figure from the hydrodynamic bearing device shown above is that the reinforcing member 12 is arranged not on the outer surface side of the housing 7 but on the inner surface side of the housing 7. In this embodiment, as shown in FIG. 6B, the radial direction portion 12b of the reinforcing member 12 extends to the inner diameter side to a position exceeding the outer peripheral surface 2b3 of the flange portion 2b, and the upper end surface 12b2 is the housing 7 Since it is provided flush with the bottom inner bottom surface 7c1, the axial load applied to the bottom portion 7c via the flange portion 2b can be directly received by the radial portion 12b. Therefore, it is possible to prevent deformation of the bottom portion 7c when a load is applied, as well as a dynamic pressure groove (strictly speaking, dynamic pressure) that is a concern when the flange portion 2b is in strong pressure contact with the inner bottom surface 7c1 of the housing 7. Damage to the “back” section that divides the groove can be prevented, and a decrease in rotational performance in the second thrust bearing portion T2 can be effectively prevented.

  Although the case where the reinforcing member 12 is provided on the outer surface side or the inner surface side of the housing 7 has been described above, the reinforcing member 12 may be embedded in the housing 7 from the viewpoint of increasing the strength of the housing bottom 7c. Yes (not shown).

  Moreover, although illustration is abbreviate | omitted, the structure of this invention can be used suitably also with respect to the hydrodynamic bearing apparatus of the form shown in FIG.

  In the above description, the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2 are exemplified by the configuration in which the dynamic pressure action of the lubricating oil is generated by the herringbone-shaped or spiral-shaped dynamic pressure grooves. So-called step bearings, multi-arc bearings, or non-circular bearings may be used as the portions R1 and R2, and so-called step bearings and wave bearings may be employed as the thrust bearing portions T1 and T2. In addition to the configuration in which the two radial bearing portions are separated from each other in the axial direction as in the radial bearing portions R1 and R2, one radial bearing portion is provided over the upper and lower regions on the inner peripheral side of the bearing sleeve 8. It is good also as the provided structure. Furthermore, a so-called perfect circular bearing having no dynamic pressure generating portion may be used as the radial bearing portions R1 and R2, and a pivot bearing that contacts and supports one end of the shaft member may be employed as the thrust bearing portion.

It is sectional drawing of the spindle motor for information devices incorporating the hydrodynamic bearing apparatus which concerns on this invention. It is sectional drawing which shows 1st Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. It is sectional drawing of a bearing sleeve. It is sectional drawing which shows 2nd Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. (A) The figure is sectional drawing which shows 4th Embodiment of the hydrodynamic bearing apparatus based on this invention, (b) A figure is a partially expanded cross section of (a) figure. It is sectional drawing which shows notionally the hydrodynamic bearing apparatus of a conventional structure.

Explanation of symbols

1, 21, 31, 41 Hydrodynamic bearing device 2 Shaft member 7 Housing 7a Small diameter portion (side portion)
7b Large diameter part (side)
7c Bottom portion 8 Bearing sleeve 9 Seal member 9a First seal portion 9b Second seal portion 12 Reinforcing member 12a Axial portion 12b Radial portion R1, R2 Radial bearing portion T1, T2 Thrust bearing portion S1 First seal space S2 Second Seal space

Claims (5)

The sides and bottom possess integrally, and made of a resin housing that will be fixed to the inner periphery of the bracket, fixed to the inner periphery of the housing, the bearing sleeve having one end face facing the first thrust bearing gap, bearing sleeve In a hydrodynamic bearing device comprising a radial bearing portion for supporting a shaft to be supported by an oil film generated in a radial bearing gap facing an inner peripheral surface of the bearing in a radial direction,
Ri Do from the axial portion and integral therewith in the radial portion having a fixing surface for the bracket to the outer peripheral surface, the axial portion is more provided with metal reinforcing member in the circumferential direction is arranged on the bottom side corner portions of the housing The hydrodynamic bearing device is characterized in that the housing is injection-molded with the reinforcing member as an insert part . The hydrodynamic bearing device according to claim 1, wherein an outer peripheral surface of the axial portion of the reinforcing member and an outer peripheral surface of the housing are flush with each other.   The hydrodynamic bearing device according to claim 1, wherein the radial direction portion of the reinforcing member extends to the inner diameter side to a position exceeding the inner peripheral surface of the side portion of the housing.   The hydrodynamic bearing device according to claim 1, wherein the axial direction portion of the reinforcing member extends to a position exceeding the bottom inner surface of the housing. The shaft to be supported has a flange portion disposed between the bottom portion of the housing and the bearing sleeve, and the radial direction portion of the reinforcing member extends to the inner diameter side to a position exceeding the outer peripheral surface of the flange portion. The hydrodynamic bearing device according to claim 1.

Images