JP4754794B2 - Fluid bearing unit, spindle motor having the fluid bearing unit, and recording disk drive - Google Patents

Description

  The invention of the present application relates to a fluid bearing unit capable of exerting a bearing function with respect to loads in both radial and axial directions, which can be standardized by modularizing components and unitizing the entire finished product. The present invention also relates to a spindle motor and a recording disk drive apparatus provided with the fluid dynamic bearing unit.

  In recent years, spindle motors used as drive devices / parts for rotating units such as office automation devices such as computers, which have become increasingly larger and smaller in size, and magnetic disk drive devices, which are peripheral devices, have motor runout accuracy ( There is a strong demand for reliability such as NRRO (asynchronous vibration), noise, acoustic life, and rigidity.

  Conventionally, a compound ball bearing device constituted by combining a plurality of ball bearings is often used for the bearing portion of the rotating shaft of such a spindle motor. Recently, in magnetic disk drive devices and the like, there has been a strong demand for increased recording capacity, improved impact resistance, low noise and faster data access. To meet these demands, spindle motors Ball bearings are improved in material composition and processing accuracy of inner and outer rings and rolling elements, etc., but these measures are not sufficient, and the limitations of rolling bearings themselves are recognized. In order to cope with this, the mounting of fluid bearings has been promoted.

  FIG. 13 shows a shaft rotation type spindle motor on which such a fluid bearing is mounted. The spindle motor 00 includes a base 02, a rotor hub 03 that is supported by the base 02 and rotates, and a hydrodynamic bearing device 01 interposed between the base 02 and the rotor hub 03.

  The sleeve 010 of the hydrodynamic bearing device 01 is fitted and fixed to the inner peripheral surface of the cylindrical wall 07 at the center of the base 02, and the rotary shaft 030 suspended from the rotor hub 03 is fitted into the sleeve 010. ing. A minute gap between the sleeve 010 and the rotating shaft 030 is filled with lubricating oil, and a dynamic pressure groove (for example, a herringbone-shaped groove) 051 formed on the inner peripheral surface of the sleeve 010 as the rotating shaft 030 rotates. , 052, the rotating shaft 030 is rotatably supported in the radial direction in a non-contact state with the inner peripheral surface of the sleeve 010 by the dynamic pressure obtained by generating the lubricating oil pressure by the action of. Although the dynamic pressure grooves 051 and 052 are formed at two locations on the upper and lower sides of the inner peripheral surface of the sleeve 010, these dynamic pressure grooves may be formed on the outer peripheral surface of the rotating shaft 030.

Although not shown in detail, the dynamic pressure grooves (for example, the upper surface of the counter plate 020 and the lower end surface of the sleeve 010 facing the lower end surface and the upper end surface of the thrust ring 060 fitted to the lower end portion of the rotary shaft 030 respectively. Herringbone-shaped grooves) are formed, and the minute gaps between the facing surfaces where these dynamic pressure grooves face each other are filled with lubricating oil, and by the action of these dynamic pressure grooves as the rotary shaft 030 rotates. The thrust ring 060 is rotatably supported in the axial direction in a non-contact state with the upper surface of the counter plate 020 and the lower end surface of the sleeve 010 by the dynamic pressure obtained by the generation of the lubricating oil pressure. These dynamic pressure grooves may be formed on the lower end surface and the upper end surface of the thrust ring 060 , respectively.

  Therefore, the base 02 rotatably supports the rotating shaft 030 of the rotor hub 03 via the hydrodynamic bearing device 01. In addition, the structure of the motor unit including the stator 05, the permanent magnet 06, and the like is basically not different from a spindle motor using a conventional compound ball bearing.

  Conventionally, the hydrodynamic bearing device 01 has not been modularized in the components such as the sleeve 010, the rotary shaft 030, the counter plate 020, and the like. When a hydrodynamic bearing device is required, the manufacturer of the device / equipment must replace each part with a structure and performance suitable for each device / device to which the hydrodynamic bearing device is applied. The manufacturer has to manufacture the hydrodynamic bearing device individually and complete the hydrodynamic bearing device, and it is not easy to rapidly mass-produce high performance, long-life hydrodynamic bearing devices.

  At the spindle motor level, the components that make it up are modularized as much as possible, and the parts including the hydrodynamic bearing device are shared. For diversification, the common parts can be used as they are, and even if some parts are defective, only the parts need to be replaced. It has already been proposed to reduce costs through these measures (see Japanese Patent Application Laid-Open Nos. 2000-175405, 56-157427, and 56-133121). The “parts” mentioned here include “combination parts” formed by combining a plurality of “parts as minimum units” in addition to “parts as minimum units”.

However, these modularized parts have their structures and dimensions determined so as to be compatible with the spindle motor, and have not been standardized so that they can be used in common with various devices and apparatuses.
JP 2000-175405 A Japanese Utility Model Publication No. 56-157427 Japanese Utility Model Publication No. 56-133121

  The invention of the present application solves the above-mentioned problems of the conventional hydrodynamic bearing device and constitutes the hydrodynamic bearing device when modularizing the hydrodynamic bearing device which is one of the “combined parts” of the spindle motor. By further modularizing “parts as minimum units” and unitizing hydrodynamic bearing devices corresponding to “finished products” (combined parts) for “parts as minimum units”, not only spindle motors. The hydrodynamic bearing device of various specifications standardized so that it can be used in common with various devices and devices can be easily manufactured, and these devices can be used as bearing devices for the rotary drive part of any device or device.・ Equipment manufacturers immediately procure these “combination parts” or “parts as minimum units” and combine them as necessary to provide the desired structure and functions. A hydrodynamic bearing unit having a structure suitable for unitization, in particular, a hydrodynamic bearing unit capable of exhibiting a bearing function against radial and axial loads, and the hydrodynamic bearing unit. It is an object of the present invention to provide a spindle motor and a recording disk drive device provided.

The invention of the present application relates to a hydrodynamic bearing unit that has solved the above-described problems, a spindle motor including the hydrodynamic bearing unit, and a recording disk drive device.
The invention described in claim 1 is configured by combining a plurality of modularized elements, and includes a flanged shaft element having a plurality of dynamic pressure generating mechanism portions therein and a flange portion at one end portion. A hydrodynamic bearing unit that is rotatably supported, a cylindrical case element having a cylindrical inner peripheral surface, an end plate element that closes a lower end of the case element, and an outer ring element that is fitted into the case element; A flanged shaft element inserted into the outer ring element so that the flange portion is sandwiched between the lower end surface of the outer ring element and the upper surface of the end plate element, or the inner peripheral surface of the outer ring element or the On the outer peripheral surface of the main body portion of the shaft element with flange, a first dynamic pressure groove for generating a dynamic pressure that receives a load in the radial direction is formed between the opposing surfaces. A second dynamic pressure groove is formed on the lower end surface of the outer ring element or on the upper surface of the flange portion of the flanged shaft element to generate a dynamic pressure that receives a load in the axial direction between the opposing surfaces. On the upper surface of the end plate element or the lower surface of the flange portion of the flanged shaft element, a third dynamic pressure groove for generating a dynamic pressure to receive a load in the axial direction is formed between the opposing surfaces. The minute gaps between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove are filled with lubricating oil, and at least the case element and the end plate element The flanged shaft element is finished with high accuracy, and the hydrodynamic bearing unit is fitted and fitted to the mating member to which it is assembled with high accuracy. The element in which any one of the first to third dynamic pressure grooves is formed on any surface thereof is made of hardenable steel or hardenable stainless steel, and is subjected to heat treatment to be ground. After finishing, the dynamic pressure grooves are formed by electrolytic processing, and among the plurality of elements, the joint surfaces or sliding surfaces between both adjacent elements are all parallel to the axial direction of the flanged shaft element. Or a hydrodynamic bearing unit characterized by being in an orthogonal relationship .

  Since the invention described in claim 1 is configured as described above, the hydrodynamic bearing unit for supporting a flanged shaft element having a flange portion at one end thereof in a relatively rotatable manner modularizes each element. Therefore, it is possible to easily manufacture a standardized hydrodynamic bearing unit with modularized elements.

In addition, the element in which the dynamic pressure groove is formed on either surface is made of quenchable steel or quenchable stainless steel, subjected to heat treatment, ground, and then electrolytically processed. Since the dynamic pressure groove is formed, the element in which the dynamic pressure groove is formed on either surface has high hardness and high dimensional accuracy, and can be handled as a unit (assembled) or as a single element. Not only at times, but also when the hydrodynamic bearing unit is stopped or started to rotate, it is difficult to be damaged and high dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. In addition, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.

  The second dynamic pressure groove can be used even when it is not expected to always press the flanged shaft element in the axial direction toward the end plate element due to a bias effect such as a magnetic force acting between the rotating side element and the fixed side element. Between the facing surfaces facing each other (meaning “between the two opposing surfaces”; hereinafter the same. Here, it means between the lower end surface of the outer ring element facing each other and the upper surface of the flange portion of the flanged shaft element). The dynamic pressure generated in the dynamic pressure generating mechanism portion (hereinafter abbreviated as “dynamic pressure generating portion”) formed in the small gap of () can exert an equivalent action. As a result, the relative clearance of the flanged shaft element can be reduced by keeping both the minute gap between the opposing surfaces facing the second dynamic pressure groove and the minute gap between the opposing surfaces facing the third dynamic pressure groove at an appropriate gap. It is possible to stabilize and improve the rotation accuracy.

Further, by forming a fluid bearing unit according to claim 1 Symbol mounting as claimed in claim 2, the first dynamic pressure grooves, the axial direction of the element having a surface animal grooves are formed It is formed in two places above and below that are separated. As a result, the shaft element is supported by the bearing directly or indirectly in the radial direction at two axially upper and lower portions, so that high bearing rigidity can be obtained. This is particularly advantageous when the axial dimension of the hydrodynamic bearing unit is increased.

The invention described in claim 3 is a flanged shaft element that is configured by combining a plurality of modularized elements, has a plurality of dynamic pressure generating mechanism sections therein, and has a flange section at one end. A cylindrical case element having a cylindrical inner peripheral surface, an end plate element that closes a lower end portion of the case element, and a first fitting element that is fitted into the case element. The first outer ring element and the second outer ring element, and the flange portion of the outer ring element and the second outer ring element are sandwiched between the lower end surface of the second outer ring element and the upper surface of the end plate element. A flanged shaft element inserted into the outer ring element and a flange of the flanged shaft element to position the second outer ring element relative to the end plate element. An annular spacer element provided so as to surround the portion, and a radial load is applied to the inner peripheral surface of the first outer ring element or the outer peripheral surface of the main body portion of the flanged shaft element between the opposing surfaces. A first dynamic pressure groove for generating a received dynamic pressure is formed, and the inner peripheral surface of the second outer ring element or the outer peripheral surface of the main body portion of the flanged shaft element is radially between the opposing surfaces. A second dynamic pressure groove for generating a dynamic pressure that receives a load in a direction is formed, and the lower surface of the second outer ring element or the upper surface of the flange portion of the flanged shaft element is formed between the opposing surfaces. A third dynamic pressure groove for generating a dynamic pressure that receives a load in the axial direction is formed on the upper surface of the end plate element or the flange of the flanged shaft element. A fourth dynamic pressure groove for generating a dynamic pressure that receives a load in the axial direction is formed between the opposing surfaces on the lower surface of the first portion, and the first dynamic pressure groove and the second dynamic pressure are formed. The minute gaps between the opposing surfaces facing the groove, the third dynamic pressure groove, and the fourth dynamic pressure groove are filled with lubricating oil, and at least the case element, the end plate element, and the flanged shaft The element is finished with high accuracy, and the hydrodynamic bearing unit is fitted and fitted with high accuracy to a mating member to which the fluid bearing unit is to be assembled. The element in which the dynamic pressure groove is formed is made of quenchable steel or quenchable stainless steel, and after heat treatment and grinding finish, the dynamic pressure groove is formed by electrolytic processing. Among the plurality of the elements, The fluid bearing unit is characterized in that the joint surfaces or sliding surfaces between the two adjacent elements are all in parallel or orthogonal to the axial direction of the flanged shaft element .

Since the invention described in claim 3 is configured as described above, the hydrodynamic bearing unit for supporting a flanged shaft element having a flange portion at one end thereof in a relatively rotatable manner modularizes each element. Therefore, it is possible to easily manufacture a standardized hydrodynamic bearing unit with modularized elements.

  In addition, the radial gap dimension formed by the first outer ring element and the flanged shaft element and the radial gap dimension formed by the second outer ring element and the flanged shaft element have different dimensions. By setting, it becomes possible to adjust the dynamic pressure which receives the load of the radial direction produced | generated in the dynamic pressure generation part formed in each clearance gap according to a desired use condition.

  Further, in the hydrodynamic bearing unit having the same height, the first outer ring element and the flanged shaft element can be combined by variously changing the axial height of the first outer ring element and the axial height of the second outer ring element. The radial direction load generated by the dynamic pressure generating portions respectively formed in the radial gap formed by the second outer ring element and the radial gap formed by the flanged shaft element. The dynamic pressure to be received and the position where the dynamic pressure is generated can be adjusted in accordance with the desired usage conditions.

  Further, the axial position of the first outer ring element and the second outer ring element can be accurately adjusted and set with respect to the end plate element according to the flanged shaft element having a different thickness of the flange portion by the spacer element. it can.

In addition, the element in which the dynamic pressure groove is formed on either surface is made of quenchable steel or quenchable stainless steel, subjected to heat treatment, ground, and then electrolytically processed. Since the dynamic pressure groove is formed, the element in which the dynamic pressure groove is formed on either surface has high hardness and high dimensional accuracy, and can be handled as a unit (assembled) or as a single element. Not only at times, but also when the hydrodynamic bearing unit is stopped or started to rotate, it is difficult to be damaged and high dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. In addition, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.

  Further, even when the flanged shaft element cannot be expected to always be pressed in the axial direction toward the end plate element due to a bias effect such as a magnetic force acting between the rotating side element and the fixed side element, the third The dynamic pressure generated in the dynamic pressure generating portion formed in the minute gap between the opposing surfaces facing the dynamic pressure groove can exert the equivalent action, and thereby the facing facing the third dynamic pressure groove It is possible to stabilize the relative rotation of the shaft element with the flange and improve the rotation accuracy by keeping both the minute gap between the faces and the minute gap between the opposing faces where the fourth dynamic pressure groove faces. it can.

Further, by configuring the hydrodynamic bearing unit according to any one of claims 1 to 3 as described in claim 4 , a step portion is formed at the lower end portion of the case element, and the end plate element is connected to the step plate element. The case element is fitted to close the lower end of the case element.

As a result, the end plate element is fitted into the lower end portion of the case element, which can be expected to be remarkably improved by grinding simultaneously with the inner peripheral surface of the case element. Since the upper surface of the end plate and the axis of the case element are easily perpendicular, the assembly accuracy of each element constituting the hydrodynamic bearing unit is improved, and the shaft element has a high relative rotation. Accuracy can be obtained.

Furthermore, by configuring the hydrodynamic bearing unit according to any one of claims 1 to 4 as described in claim 5 , a bearing container configured by closing a lower end portion of the case element with an end plate element is provided. , Formed by integral molding of the same material.

As a result, the number of elements constituting the hydrodynamic bearing unit can be reduced by one, and the work of fitting the end plate element to the lower end of the case element can be omitted, so that the hydrodynamic bearing unit is assembled (unitized). Work can be simplified.

According to a sixth aspect of the present invention, there is provided a spindle motor comprising the hydrodynamic bearing unit according to the first or third aspect , wherein the stator motor is fixed to the housing, and is fitted to the upper end portion of the shaft portion. A rotor hub that forms a rotating element, and a rotor magnet that is fitted to the rotor hub and generates a rotating magnetic field in cooperation with the stator, and is provided to be rotatable with respect to the housing. The hydrodynamic bearing unit is a spindle motor that supports the rotation of the rotor.

Since the invention described in claim 6 is configured as described above, a fluid bearing unit having a desired structure and bearing performance as a fluid bearing to be provided by the spindle motor is immediately procured. Thus, it is possible to mass-produce spindle motors having high rotational accuracy and high reliability at low cost.

Furthermore, the invention described in claim 7 is a recording disk drive device comprising the spindle motor according to claim 6 , wherein a recording head for writing and / or reading information on the recording disk is provided. And the spindle motor drives to rotate the recording disk.

Since the invention described in claim 7 is configured as described above, a fluid bearing unit having a desired structure and bearing performance as a fluid bearing to be provided by the spindle motor is immediately procured. Therefore, it is possible to mass-produce spindle motors with high rotational accuracy and high reliability at low cost. It becomes possible to do.

As described above, according to the present invention, the fluid bearing unit for relatively rotatably supporting the flanged shaft element having a flange portion at one end, one end of the case element is closed by an end plate element the outer ring element of various specifications in the interior of the bearing container constituted, first outer ring element, a second outer element, scan pacer element, shaft element and the like, the relationship to fit or insert one into the other, combined in suitably mutually Are stored and fixed, and dynamic pressure grooves for generating a dynamic pressure to receive a load in a radial direction or an axial direction are formed on a predetermined surface of a predetermined element. gap the lubricant is filled in at least the case element, the end plate element and flanged shaft element is finishing with high accuracy, the fluid bearing unit, The element on which one of the dynamic pressure grooves is formed on either side is made of hardenable steel or hardenable stainless steel. After the heat treatment and grinding finish, the dynamic pressure groove is formed by electrolytic processing, and the joint surface or sliding surface between both adjacent elements among the plurality of elements is all Since it is configured to be parallel or orthogonal to the axial direction of the flanged shaft element , the hydrodynamic bearing unit is easy to modularize each element and is modularized. A fluid bearing unit standardized with each element can be easily manufactured.

  As a result, fluidized bearing units with various specifications standardized so that they can be used in common with various devices and apparatuses can be easily manufactured. As a bearing device for the rotary drive part of any device or apparatus, The manufacturers of these devices and equipment immediately procure these hydrodynamic bearing units or various elements as their components and combine them as necessary to obtain the desired structure and dynamic pressure bearing function (for both radial and axial loads). In addition, it is easy to select an optimum design and a desired configuration from the standpoint of using the bearing device.

  Conventionally, fluid dynamic pressure bearings have been used only for limited technical fields and applications due to various obstacles (component supply system, bearing assembly system, etc.) In the invention of the present application, standardization is achieved by modularizing the component parts and unitizing the finished product as described above, as desired by engineers who are engaged in the development of products such as equipment and devices on which bearings are mounted. It is possible to easily provide fluid dynamic pressure bearings of various and diverse specifications, and provide these engineers with the opportunity to adopt fluid dynamic pressure bearings equally and evenly. It becomes possible to use a fluid dynamic pressure bearing for the application.

  Further, at least the element in which the dynamic pressure groove is formed is made of quenchable steel or quenchable stainless steel material, and after heat treatment and grinding finish, the dynamic pressure groove is formed by electrolytic processing. Therefore, an element with high hardness and high dimensional accuracy can be obtained, and scratches can be obtained not only when unitizing (assembling) or handling the element alone, but also when the hydrodynamic bearing unit is stopped or rotated. It is difficult to stick and high dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. In addition, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.

  In particular, if the hydrodynamic bearing unit of the present invention is applied as a hydrodynamic bearing provided in a spindle motor, a standardized hydrodynamic bearing unit having a desired structure and bearing performance can be procured immediately, with high rotational accuracy and high reliability. Therefore, it is possible to mass-produce the spindle motor equipped with the above-mentioned at a low cost, and to mass-produce the recording disk drive device equipped with the spindle motor at a low cost.

A fluid bearing unit for relatively rotatably supporting the flanged shaft element having a flange portion at one end, the case element, the end plate elements, an outer ring element, a first outer ring element, a second outer element, the spacer element, the shaft An element such as an element is disassembled into a plurality of elements that can be easily modularized, and an outer ring element of various specifications, a first outer ring element, the second outer ring element, the scan pacer element, the shaft element or the like, the relationship to fit or insert one into the other, collection appropriately combined each other, and fixed, on the predetermined surface of a predetermined element, radial or axial A dynamic pressure groove for generating a dynamic pressure that receives a load in a direction is formed, and lubricating oil is filled in the minute gaps between the opposing surfaces facing each dynamic pressure groove. At least the case element, end plate element and flanged shaft element are finished with high precision, and the hydrodynamic bearing unit is fitted and fitted to the mating member to which it is assembled with high precision. The element in which the groove is formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to a heat treatment and ground to finish, and then the dynamic pressure groove is formed by electrolytic processing. In addition, among the plurality of elements, the joint surfaces or sliding surfaces between the two adjacent elements are all parallel or orthogonal to the axial direction of the flanged shaft element.
In this way, a hydrodynamic bearing unit having a desired structure and a hydrodynamic bearing function (including bearing rigidity against loads in both radial and axial directions) is obtained.

Next, a first embodiment (embodiment 1) of the present invention will be described.
FIG. 1 is a longitudinal sectional view of a fluid dynamic bearing unit according to the first embodiment. As shown in FIG. 1, this hydrodynamic bearing unit 1 is a hydrodynamic bearing unit that supports a flanged shaft element 40 having a flange portion 42 at one end portion (lower end portion in FIG. 1) in a relatively rotatable manner. A cylindrical case element 10 having a cylindrical inner peripheral surface 11, a disc-shaped end plate element 20 that closes a lower end portion of the case element 10, a cylindrical outer ring element 30 fitted into the case element 10, and A flanged shaft element 40 is inserted into the outer ring element 30 such that the flange portion 42 is sandwiched between the lower end surface 32 of the outer ring element 30 and the upper surface 21 of the end plate element 20.
In the present specification, one of the openings of the cylindrical case element 10 is closed by the end plate element 20, that is, the opening side of the bearing container, that is, the shaft element 40 extends from the bearing container. The protruding side (upper side in FIG. 1) is defined as the upper side.

  The hydrodynamic bearing unit 1 is generally used with the flanged shaft element 40 as the rotation side, but is integrated with the case element 10 side, that is, the case element 10, the end plate element 20 and the outer ring element 30. In some cases, the solid is used with the rotation side. In some cases, the illustrated posture may be used upside down.

  A first dynamic pressure groove 51 for generating a dynamic pressure to receive a load in the radial direction between the inner peripheral surface 31 of the outer ring element 30 and the outer peripheral surface 43 of the main body 41 of the flanged shaft element 40. (51-1, 51-2) is formed, and the lower end surface 32 of the outer ring element 30 is subjected to a dynamic pressure that receives a load in the axial direction between the upper surface 44 of the flange portion 42 of the opposed shaft element 40 with flange. A second dynamic pressure groove 52 is formed for generation, and the upper surface 21 of the end plate element 20 is subjected to an axial load between the lower surface 45 of the flange portion 42 of the opposed flanged shaft element 40. A third dynamic pressure groove 53 for generating pressure is formed. These dynamic pressure grooves 51 to 53 are formed in a herring bone (fishbone) shape, but are not necessarily limited to this shape, and may be formed in a spiral shape, an arc shape, a linear shape, or the like.

  The first dynamic pressure grooves 51 are formed at two upper and lower portions separated in the axial direction of the inner peripheral surface 31 of the outer ring element 30 as indicated by reference numerals 51-1 and 51-2 in the drawing. By doing in this way, the shaft element 40 is supported by bearings at two upper and lower portions, so that a high bearing rigidity can be obtained. In particular, the axial dimension of the case element 10 and, therefore, the fluid bearing unit can be obtained. This is advantageous when the axial dimension of 1 is large. As the axial dimension of the case element 10 is reduced, only one location may be formed.

  Lubricating oil is filled in the minute gaps between the opposing surfaces facing the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53, respectively. Has been. In this lubricating oil filling method, after the outer ring element 30 and the flanged shaft element 40 are built in the case element 10 and one end of the case element 10 is closed by the end plate element 20, a minute gap between the elements is formed. In addition, the lubricating oil is filled from the sealing mechanism portion 60 of the lubricating oil. The lubricating oil sealing mechanism 60 is formed of a minute gap formed between the outer ring surface 30 and the outer peripheral surface 43 of the main body 41 of the flanged shaft element 40 by slightly expanding the open end side of the outer ring element 30.

  The minute gap of the lubricating oil seal mechanism 60 has a width larger than the minute gap that the upper first dynamic pressure groove 51-1 faces. For this reason, the first dynamic pressure groove as described above. 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53, the lubricating oil for generating dynamic pressure sequentially filled in the minute gaps between the facing surfaces facing each other, Since the capillary force acts as a holding force for the lubricating oil in the narrow gap of the widened seal mechanism 60, the leak does not leak to the outside open end side through the minute gap of the seal mechanism 60.

In the element in which the dynamic pressure groove is formed, in the first embodiment, the outer ring element 30 and the end plate element 20 are manufactured from a hardenable steel or a hardenable stainless steel material and subjected to a heat treatment. The first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53 are formed by electrolytic processing after the grinding finish. . In the case where a hardenable steel or a hardenable stainless steel material is used for the outer ring element 30, the inner peripheral surface, the outer peripheral surface and both end surfaces are finished by grinding after the heat treatment. Further, when using a hardenable steel or a hardenable stainless steel material for the end plate element 20, the upper surface and the outer peripheral surface are finished by grinding after the heat treatment.
The flanged shaft element 40 may be manufactured from the same material, heat-treated in the same manner, and finished by grinding. The end plate element 20 may be manufactured from a normal stainless steel material, and DLC (Diamond-Like Carbon) It is also possible to increase the surface hardness by applying a coating such as

  The flange portion 42 of the flanged shaft element 40 is formed integrally with the main body portion 41. However, these are formed separately, and methods such as press-fitting, adhesion, caulking, welding, or the like are used together. The flanged shaft element 40 can be assembled by the above-described method.

A step portion 12 is formed at the lower end portion of the case element 10, so that the outer peripheral edge portion of the end plate element 20 is fitted therein, and the lower end portion of the case element 10 is closed by the end plate element 20. It has become.
The two perpendicular surfaces facing the stepped portion 12 can be ground simultaneously with the inner peripheral surface 11 of the case element 10, so that a significant improvement in accuracy can be expected, and the end plate element 20 is fitted here. As a result, the right angle between the upper surface 21 of the end plate 20 and the axial center of the case element 10 can be easily obtained, and the assembly accuracy of each element constituting the fluid dynamic bearing unit 1 is improved. Rotational accuracy can be obtained.

  The integrated assembly configured by closing the lower end portion of the case element 10 with the end plate element 20 stores therein other elements such as the shaft element 40, and thus has characteristics as a bearing container. It is also possible to form the bearing container by integral molding of the same material. The bearing container formed by integral molding in this way constitutes one bearing container element and can be modularized. Thereby, the number of elements can be reduced by one, the work of fitting the end plate element 20 to the lower end of the case element 10 can be omitted, and the structure and assembly work of the hydrodynamic bearing unit 1 can be simplified. .

  The insertion of the outer ring element 30 into the case element 10 is preferably fixed by a fixing method such as shrink fitting, caulking, adhesive, etc. so that they can be fixed and rotated as a unit. .

  In addition, select materials with as little difference in linear expansion coefficient as possible so that the dimensional relationship and positional relationship during assembly are maintained in all operating temperature environments, roundness, cylindricity, surface roughness, flatness, parallelism It is important to improve processing and assembly accuracy related to the degree.

  Further, in order to standardize the hydrodynamic bearing unit 1 of the first embodiment so that it can be used in common with various devices and apparatuses, high-precision fitting / fitting with a mating member to which the fluid bearing unit 1 is assembled. In order to achieve wear, sufficient attention must be paid to the accuracy of the case elements and end plate elements, such as the outer shape, dimensions, surface properties, shaft element outer diameter, surface properties, etc. The roundness, cylindricity or columnarity, surface roughness, etc., must be finished with high accuracy. In addition, the variation in the diameter and width of these elements should be suppressed as much as possible.

  The first embodiment is configured as described above, and the hydrodynamic bearing unit 1 includes a case element 10, an end plate element 20, an outer ring element 30, and a shaft element 40 with a flange. A first dynamic pressure groove 51 is formed on the inner peripheral surface of the element 30, a second dynamic pressure groove 52 is formed on the lower end surface of the outer ring element 30, and a third dynamic pressure groove 52 is formed on the upper surface of the end plate element 20. Since the pressure grooves 53 are formed and the lubricating oil is filled in the minute gaps between the facing surfaces that the dynamic pressure grooves 51 to 53 face, the joint surfaces or sliding surfaces between the adjacent elements. Are all parallel to or perpendicular to the axial direction of the shaft element 40 with flange, that is, the axial direction of the hydrodynamic bearing unit 1, and each element can be easily modularized in this way. Each element The standardized fluid bearing unit with can be easily manufactured.

Moreover, since the outer ring element 30 and the end plate element 20 which are elements in which the dynamic pressure grooves 51 to 53 are formed are manufactured from a hardenable steel material or a hardenable stainless steel material, the hardness is high and the dimensional accuracy is high. Element can be obtained, and a plurality of elements are assembled to complete the hydrodynamic bearing unit 1 (unit assembly), not only when handling the element alone, but also when the hydrodynamic bearing unit 1 is stopped or rotated Even at the time of start-up, scratches are difficult to be made and high dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. Moreover, the machining time for forming the dynamic pressure groove can be shortened by electrolytic machining.

Furthermore, even when the shaft element 40 cannot always be pressed in the axial direction toward the end plate element 20 due to a bias effect such as a magnetic force acting between the rotation side element and the fixed side element, the second dynamic pressure groove The dynamic pressure generated in the dynamic pressure generating portion formed in the minute gap between the facing surfaces facing the surface 52 can also exhibit an equivalent effect, whereby the facing surface facing the second dynamic pressure groove 52 faces. The relative clearance of the flanged shaft element 40 can be stabilized and the rotation accuracy can be improved by keeping both the minute gap between the two and the minute gap between the facing surfaces facing the third dynamic pressure groove 53 at appropriate gaps. Can do.
In addition, various effects as described above can be achieved.

  In the first embodiment, the first to third dynamic pressure grooves 51 to 53 are formed on the inner peripheral surface 31 of the outer ring element 30, the lower end surface 32 of the outer ring element 30, and the upper surface 21 of the end plate element 20, respectively. However, the present invention is not limited thereto, and is formed on the outer peripheral surface 43 of the main body portion 41 of the flanged shaft element 40, the upper surface 44 of the flange portion 42 of the flanged shaft element 40, and the lower surface 45 thereof. May be. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, a second embodiment (embodiment 2) of the present invention will be described.
FIG. 2 is a longitudinal sectional view of the fluid dynamic bearing unit of the second embodiment, and the same reference numerals are given to the portions corresponding to the first embodiment.
As shown in FIG. 2, the hydrodynamic bearing unit 1 of the second embodiment is a hydrodynamic bearing unit that supports a straight shaft element 40 so as to be relatively rotatable, and has a cylindrical shape having a cylindrical inner peripheral surface 11. Case element 10, disk-shaped end plate element 20 that closes the lower end of case element 10, cylindrical outer ring element 30 that is fitted into case element 10, and shaft element 40 that is inserted into outer ring element 30 The first dynamic pressure groove 51 (for generating a dynamic pressure receiving a radial load between the inner peripheral surface 31 of the outer ring element 30 and the outer peripheral surface 43 of the opposing shaft element 40 is provided. 51-1 and 51-2) are formed, and a second dynamic pressure is generated on the upper surface 21 of the end plate 20 to receive a load in the axial direction between the lower end surface 46 of the opposing shaft element 40. Dynamic pressure 52 is formed, the small gaps between the opposed surfaces facing the first dynamic pressure groove 51 (51-1 and 51-2) and a second dynamic pressure groove 52, respectively, the lubricating oil is filled.

In the second embodiment, the outer ring element 30 and the end plate element 20 are manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to a heat treatment, and finished by grinding. Then, the first dynamic pressure groove 51 (51-1, 51-2) and the second dynamic pressure groove 52 are formed by electrolytic processing.
Since other configurations are not different from those of the first embodiment, detailed description thereof is omitted.

  Since the second embodiment is configured as described above, the hydrodynamic bearing unit 1 that supports the straight shaft element 40 so as to be relatively rotatable is similar to the first embodiment. The case element 10, the end plate element 20, the outer ring element 30, and the straight shaft element 40 can be easily modularized, and a standardized hydrodynamic bearing unit can be easily manufactured using the modularized elements in this way. can do.

  Further, the outer ring element 30 and the end plate element 20 which are elements in which the dynamic pressure grooves 51 (51-1, 51-2) and 52 are formed are manufactured from a hardenable steel material or a hardenable stainless steel material, Since these dynamic pressure grooves are formed by electrolytic processing after heat treatment and grinding finish, these elements with high hardness and high dimensional accuracy can be obtained, are not easily scratched, and are high The dimensional accuracy can be maintained. In particular, it is possible to obtain a dynamic pressure groove with a fine surface roughness and maintain its shape, so that the dynamic pressure bearing function can be exhibited as designed. Processing time can also be shortened.

  Further, the hydrodynamic bearing unit 1 of the second embodiment has a simple structure as compared with the first embodiment, and the axial direction dynamic pressure (shaft element) for floating the shaft element as much as the hydrodynamic bearing unit 1 of the first embodiment. The axial force acting on the shaft element is not required to be generated in a non-contact state with the shaft element), or the shaft element is caused by a bias effect such as a magnetic force acting between the rotating side element and the stationary side element. The hydrodynamic bearing unit is suitable for use when, for example, an action of constantly pressing 40 toward the end plate element 20 in the axial direction can be expected. In addition, the same effects as those of the first embodiment can be obtained.

  In the second embodiment, the first and second dynamic pressure grooves 51 (51-1, 51-2) and 52 are respectively formed on the inner peripheral surface 31 of the outer ring element 30 and the upper surface 21 of the end plate element 20. Although formed, it is not limited to this, You may each form in the outer peripheral surface 43 of the shaft element 40 and the lower end surface 46 of the shaft element 40 which oppose these surfaces. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, a third embodiment (embodiment 3) of the present invention will be described.
FIG. 3 is a longitudinal sectional view of the fluid dynamic bearing unit of the third embodiment, and the same reference numerals are given to portions corresponding to the first embodiment.
As shown in FIG. 3, the hydrodynamic bearing unit 1 of the third embodiment has a thinner outer ring element 30 as a result of the outer ring element 30 being thinner than the hydrodynamic bearing unit 1 (FIG. 1) of the first embodiment. The difference is that an inner ring element 70 is interposed in the space between the element 30 and the flanged shaft element 40. The inner ring element 70 is inserted into the outer ring element 30 and can be rotated relative to the outer ring element 30. The flanged shaft element 40 is fitted in the inner ring element 70, and can be integrally supported by the outer ring element 30 in the radial direction and rotated. The lower end of the inner ring element 70 is in contact with the upper surface 44 of the flange portion 42 of the flanged shaft element 40.

  The first dynamic pressure groove 51 (consisting of an upper dynamic pressure groove 51-1 and a lower dynamic pressure groove 51-2) is formed on the inner peripheral surface 31 of the outer ring element 30, as in the first embodiment. Of the two opposing surfaces that form the minute gap that it faces, the surface that forms a pair with the inner peripheral surface 31 of the outer ring element 30 is the outer peripheral surface 73 of the inner ring element 70. The place where the second dynamic pressure groove 52 and the third dynamic pressure groove 53 are formed is not different from the first embodiment. Lubricating oil is filled in the minute gaps between the opposing surfaces facing the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53, respectively. Has been.

  In the third embodiment, the outer ring element 30 and the end plate element 20 are manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to a heat treatment, and finished by grinding. Then, the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53 are formed by electrolytic processing. The inner ring element 70 and the flanged shaft element 40 can also be manufactured from the same material, heat-treated, and finished by grinding.

The lubricating oil seal mechanism 60 is provided with the inner ring element 70 by slightly expanding the diameter of the open end side of the outer ring element 30 when the inner ring element 70 is provided between the outer ring element 30 and the flanged shaft element 40. It is assumed that it consists of a minute gap formed between the outer peripheral surface 73 of 70.
Since other configurations are not different from those of the first embodiment, detailed description thereof is omitted.

  Since the third embodiment is configured as described above, the hydrodynamic bearing unit 1 that supports the flanged shaft element 40 having the flange portion 42 at one end thereof in a relatively rotatable manner is similar to the first embodiment. It is easy to modularize each element constituting it, that is, the case element 10, the end plate element 20, the outer ring element 30, the inner ring element 70, and the flanged shaft element 40. The hydrodynamic bearing unit 1 standardized with elements can be easily manufactured.

Further, by using the same flanged shaft element 40 and changing the setting of the radial gap formed by the outer ring element 30 and the inner ring element 70, the dynamic pressure generating part formed in this gap part is generated. It is possible to adjust the dynamic pressure subjected to the radial load to the desired usage conditions.
In addition, the same effects as those of the first embodiment can be obtained.

In the third embodiment, the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53 are the inner peripheral surface 31 of the outer ring element 30. Although formed on the lower end surface 32 of the outer ring element 30 and the upper surface 21 of the end plate element 20, respectively, the present invention is not limited thereto, and the outer peripheral surface 73 of the inner ring element 70 and the flange of the flanged shaft element 40 are opposed to these surfaces. May be formed respectively on the upper surface 44 and the lower surface 45 of the portion 42. In this case as well, the element in which the dynamic pressure groove is formed is manufactured from a hardenable steel material or a hardenable stainless steel material and subjected to heat treatment. After applying and grinding, these dynamic pressure grooves are formed by electrolytic processing.
Even if it does in this way, there can exist an effect similar to the above.

Next, a fourth embodiment (embodiment 4) of the present invention will be described.
FIG. 4 is a longitudinal sectional view of the fluid dynamic bearing unit of the fourth embodiment, and the same reference numerals are given to the portions corresponding to the second and third embodiments.
As illustrated in FIG. 4, the hydrodynamic bearing unit 1 of the fourth embodiment has a thinner outer ring element 30 as a result of the outer ring element 30 being thinner than the hydrodynamic bearing unit 1 (FIG. 2) of the second embodiment. The difference is that a flanged inner ring element 70 is interposed between the element 30 and the straight shaft element 40. The flanged inner ring element 70 is inserted into the outer ring element 30 and can rotate relative to the outer ring element 30. The shaft element 40 is fitted into the flanged inner ring element 70, and is integrally supported by the shaft element 40 in the radial direction by the outer ring element 30 so that it can rotate.

  Further, when compared with the hydrodynamic bearing unit 1 (FIG. 3) of the third embodiment, a straight shaft element 40 is used instead of the flanged shaft element 40 of the hydrodynamic bearing unit 1 of the third embodiment, and the same straight inner ring element is used. The difference is that a flanged inner ring element 70 is used instead of 70. The shaft element 40 is fitted in the flanged inner ring element 70 and can rotate integrally therewith. The flange portion 72 of the flanged inner ring element 70 is sandwiched between the lower end surface 32 of the outer ring element 30 and the upper surface 21 of the end plate element 20 and can be rotated relative to these surfaces.

  The second dynamic pressure groove 52 is formed on the lower end surface 32 of the outer ring element 30 in the same manner as in the third embodiment. Of the two opposing surfaces forming a minute gap that the second dynamic pressure groove 52 faces, the lower end surface of the outer ring element 30 is formed. The surface which makes a pair with 32 is the upper surface 74 of the flange portion 72 of the flanged inner ring element 70. The third dynamic pressure groove 53 is formed on the upper surface 21 of the end plate element 20 in the same manner as in the third embodiment. Of the two opposing surfaces forming a minute gap that the third plate faces, the end plate element 20 is formed. The surface that forms a pair with the upper surface 21 is the lower surface 75 of the flange portion 72 of the flanged inner ring element 70. The place where the first dynamic pressure groove 51 (51-1, 51-2) is formed is not different from the third embodiment. Lubricating oil is filled in the minute gaps between the opposing surfaces facing the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53, respectively. Has been.

In the fourth embodiment, the outer ring element 30 and the end plate element 20 are manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to a heat treatment, and finished by grinding. Then, the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the second dynamic pressure groove 53 are formed by electrolytic processing. The flanged inner ring element 70 and the shaft element 40 can also be manufactured from the same material, heat-treated, and finished by grinding.
Since other configurations are not different from those of the third embodiment, detailed description thereof is omitted.

  Since the fourth embodiment is configured as described above, the hydrodynamic bearing unit 1 that supports the straight shaft element 40 in a relatively rotatable manner is similar to the second and third embodiments. That is, it is easy to modularize the case element 10, the end plate element 20, the outer ring element 30, the flanged inner ring element 70, and the straight shaft element 40, and each element thus modularized is standardized. The hydrodynamic bearing unit 1 can be easily manufactured.

Further, by using the same straight shaft element 40, by changing the setting of the radial gap formed by the outer ring element 30 and the flanged inner ring element 70, the dynamic pressure generating part formed in this gap part The dynamic pressure that receives the generated radial load can be adjusted according to the usage conditions.
In addition, the same effects as in the third embodiment can be obtained.

  In the fourth embodiment, the first dynamic pressure groove 51 (51-1, 51-2), the second dynamic pressure groove 52, and the third dynamic pressure groove 53 are the inner peripheral surface 31 of the outer ring element 30. These are formed on the lower end surface 32 of the outer ring element 30 and the upper surface 21 of the end plate element 20, respectively. However, the present invention is not limited thereto, and the outer peripheral surface 73 of the flanged inner ring element 70 and the flanged inner ring element 70 facing these surfaces. May be formed respectively on the upper surface 74 and the lower surface 75 of the flange portion 72. In this case, the element in which the dynamic pressure groove is formed is manufactured from a hardenable steel material or a hardenable stainless steel material, These heat pressure grooves are formed by electrolytic processing after heat treatment and grinding. Even if it does in this way, there can exist an effect similar to the above.

Next, a fifth embodiment (embodiment 5) of the present invention will be described.
FIG. 5 is a longitudinal sectional view of the fluid dynamic bearing unit of the fifth embodiment. As shown in the figure, the hydrodynamic bearing unit 1 of the fifth embodiment has a flanged shaft element 40 in the hydrodynamic bearing unit 1 of the first embodiment as compared with the hydrodynamic bearing unit 1 (FIG. 1) of the first embodiment. This is different in that the flange portion 42 is moved to the intermediate portion in the axial direction of the shaft element 40 and that the outer ring element 30 is divided into two parts so as to sandwich the flange portion 42 from above and below.

  Therefore, in the fifth embodiment, among the two outer ring elements sandwiching the flange portion 42 from above and below, the upper outer ring element is denoted by the same reference numeral 30 as in the first embodiment and is referred to as the first outer ring element 30. The reference numeral 80 is newly added to the lower outer ring element and is referred to as a second outer ring element 80. And the code | symbol 81, 82, 83 is attached | subjected to the inner peripheral surface of the 2nd outer ring element 80, a lower end surface, and an upper end surface, respectively, Out of the outer peripheral surface 43 of the main-body part 41 of the shaft element 40 with a flange, The upper outer peripheral surface located above and the lower outer peripheral surface located below are denoted by reference numerals 43-1 and 43-2, respectively, and the lower end surface of the shaft element 40 is denoted by new reference numeral 47. The fourth dynamic pressure groove is also given new reference numerals 91 to 94, but the other parts, which correspond to the first embodiment, are given the same reference numerals.

Hereinafter, the fluid dynamic bearing unit 1 of the fifth embodiment will be described in detail.
The hydrodynamic bearing unit 1 of the fifth embodiment is a hydrodynamic bearing unit that supports a flanged shaft element 40 having a flange portion 42 at an intermediate portion so as to be relatively rotatable, and has a cylindrical case having a cylindrical inner peripheral surface 11. Element 10, disc-shaped end plate element 20 that closes the lower end of case element 10, short cylindrical first outer ring element 30 and second outer ring element 80 that are fitted into case element 10, and The flange portion 42 is inserted into the first outer ring element 30 and the second outer ring element 80 so as to be sandwiched between the lower end surface 32 of the first outer ring element 30 and the upper end surface 82 of the second outer ring element 80. And a shaft element 40 with a flange. The lower end surface 82 of the second outer ring element 80 is in contact with the upper surface 21 of the end plate element 20, but the lower end surface 47 of the flanged shaft element 40 slightly floats from the upper surface 21 of the end plate element 20. Yes.

  And in order to generate the dynamic pressure which receives the load of a radial direction in the inner peripheral surface 31 of the 1st outer ring element 30 between the upper outer peripheral surfaces 43-1 of the main-body part 41 of the shaft element 40 with a flange which opposes. The first dynamic pressure groove 91 is formed, and the inner peripheral surface 81 of the second outer ring element 80 is in the radial direction between the lower outer peripheral surface 43-2 of the body portion 41 of the opposed shaft element 40 with flange. A second dynamic pressure groove 92 for generating a dynamic pressure that receives the load of the first outer ring element 30 is formed on the lower end surface 32 of the first outer ring element 30. A third dynamic pressure groove 93 for generating a dynamic pressure to receive a load in the axial direction is formed between the flange portions of the opposed flanged shaft element 40 on the upper end surface 83 of the second outer ring element 80. 42 lower surface 45 A fourth dynamic pressure groove 94 for generating dynamic pressure that receives a load in the axial direction is formed between the first dynamic pressure groove 91, the second dynamic pressure groove 92, and the third dynamic pressure groove. Lubricating oil is filled in the minute gaps between the opposing surfaces facing the 93 and the fourth dynamic pressure groove 94.

  In the fifth embodiment, the first outer ring element 30 and the second outer ring element 80 are manufactured from a hardenable steel material or a hardenable stainless steel material in the fifth embodiment. Is applied, and the first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and the fourth dynamic pressure groove 94 are formed by electrolytic processing. Has been. The flanged shaft element 40 may be manufactured from the same material, heat-treated in the same manner, and finished by grinding.

The flange portion 42 of the flanged shaft element 40 having the flange portion 42 at the intermediate portion is formed integrally with the main body portion 41. However, the flange portion 42 is formed separately and press-fitted, adhered, caulked, welded. The flanged shaft element 40 can also be formed by assembling to the main body portion 41 by a method such as the above or a method using a combination of these methods.
Since other configurations are not different from those of the first embodiment, detailed description thereof is omitted.

  Since the fifth embodiment is configured as described above, the hydrodynamic bearing unit 1 for supporting the flanged shaft element 40 having the flange portion at the intermediate portion thereof in a relatively rotatable manner is the same as the first embodiment. That is, it is easy to modularize the elements constituting the element, that is, the case element 10, the end plate element 20, the first outer ring element 30, the second outer ring element 80, and the shaft element 40 with the flange. The standardized hydrodynamic bearing unit 1 can be easily manufactured with modularized elements.

  Further, a radial formed by the first outer ring element 30 and a half (upper half) of the main body 41 of the flanged shaft element 40 inserted into the first outer ring element 30 with the flange 42 as a boundary. Gap direction dimension, the second outer ring element 80 and the other half part (lower half part) with the flange part 42 of the main body part 41 of the shaft element 40 with flange inserted into the second outer ring element 80 as a boundary. By setting the radial clearance dimension formed by the different dimensions, the dynamic pressure that receives the radial load generated by the dynamic pressure generation section formed in each clearance section is set to the desired usage conditions. It becomes possible to adjust according to.

  In the hydrodynamic bearing unit 1 having the same height, the ratio of the axial dimension of one half (upper half) of the main body 41 of the shaft element 40 with flange to the axial dimension of the other half (lower half) is set as follows. By changing the axial height W1 of the first outer ring element 30 and the axial height W2 of the second outer ring element 80 in various ways and combining them accordingly, the first outer ring element 30 and A radial clearance formed by one half of the main body 41 of the flanged shaft element 40 and a radial clearance formed by the second outer ring element 80 and the other half of the main body 41 respectively. It is possible to adjust the dynamic pressure generated by the formed dynamic pressure generator and receiving the load in the radial direction, and the position where the dynamic pressure is generated, according to the desired usage conditions.

Thereby, the axial height W1 of the first outer ring element 30, the axial height W2 of the second outer ring element 80, and the axial position of the flange portion 42 of the flanged shaft element 40 can be adjusted. Therefore, in the axial direction generated in the dynamic pressure generating portion formed in the minute gap between the facing surfaces where the third dynamic pressure groove 93 faces and the minute gap between the facing surfaces where the fourth dynamic pressure groove 94 faces, respectively. The generation position of the dynamic pressure that receives the load can be adjusted according to the position of the center of gravity in the axial direction of the entire rotating body including the rotating side element, and the moment acting in the direction of tilting the flanged shaft element 40 can be reduced. Thus, the whirling vibration caused by the gyro moment of the flanged shaft element 40 can be reduced, the relative rotation thereof can be stabilized, and the rotation accuracy can be improved.
In this case, if the generated dynamic pressure is made equal to the axial load, it is possible to more effectively reduce the whirling vibration caused by the gyro moment of the flanged shaft element 40. Further, in order to obtain the same effect of reducing the whirling vibration, it is possible to generate a smaller dynamic pressure by adjusting the generation position of the dynamic pressure that receives the load in the axial direction as described above. Thereby, power consumption can be reduced.

  Furthermore, the first outer ring element 30 and the second outer ring element 80, which are elements in which the dynamic pressure grooves 91 to 94 are formed, are manufactured from a hardenable steel material or a hardenable stainless steel material, and are subjected to heat treatment. Since these dynamic pressure grooves are formed by electrolytic processing after being applied and ground, these elements with high hardness and high dimensional accuracy can be obtained, scratches are difficult, and high dimensions Accuracy can be maintained. In particular, it is possible to obtain a dynamic pressure groove with a fine surface roughness and maintain its shape, so that the dynamic pressure bearing function can be exhibited as designed. Processing time can also be shortened.

Even when the shaft element 40 cannot be expected to always be pressed in the axial direction toward the end plate element 20 due to a bias effect such as a magnetic force acting between the rotation side element and the fixed side element, the third dynamic pressure is not expected. The dynamic pressure generated in the dynamic pressure generating portion formed in the minute gap between the facing surfaces where the groove 93 faces can exert the equivalent action, and thereby the facing where the third dynamic pressure groove 93 faces. It is possible to stabilize the relative rotation of the shaft element 40 and improve the rotation accuracy by keeping both the minute gap between the surfaces and the minute gap between the opposing surfaces facing the fourth dynamic pressure groove 94 at appropriate gaps. it can.
In addition, the same effects as those of the first embodiment can be obtained.

  In the fifth embodiment, the first to fourth dynamic pressure grooves 91 to 94 include the inner peripheral surface 31 of the first outer ring element 30, the inner peripheral surface 81 of the second outer ring element 80, the first Although formed on the lower end surface 32 of the outer ring element 30 and the upper end surface 83 of the second outer ring element 80, the upper outer peripheral surface of the main body portion 41 of the flanged shaft element 40 is not limited to this, and is opposed to these surfaces. 43-1, the lower outer circumferential surface 43-2, and the upper surface 44 and the lower surface 45 of the flange portion 42 of the flanged shaft element 40 may be formed respectively. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, a modification of the fifth embodiment will be described.
In the fifth embodiment, as shown in FIG. 6, the diameter D1 of one half (upper half in the figure) and the other half (see the figure) with the flange 42 of the main body 41 of the shaft element 40 with flange as a boundary. The lower half) can be deformed so as to be different from the diameter D2. In the example shown in FIG. 6, D1> D2 is set, but the present invention is not limited to this.

  According to this modification, a radial gap formed by the first outer ring element 30 and one half of the main body 41 and a second outer ring element 80 and the other half of the main body 41 are formed. The degree of freedom of adjustment of the dynamic pressure that receives the radial load generated by the dynamic pressure generating portions formed in the radial gap portions can be further expanded.

  In addition, a dynamic pressure generating portion (small diameter radial dynamic pressure bearing portion) formed in a radial gap formed by the other half portion on the small diameter side of the main body portion 41 and the second outer ring element 80. Since the friction loss can be reduced by the amount of the small diameter, the shaft loss torque can be reduced and the power consumption can be reduced (low power consumption).

  In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of tilting the flanged shaft element 40 can be reduced. The whirling vibration caused by the gyro moment can be reduced, the relative rotation can be stabilized, and the rotation accuracy can be improved.

Next, a sixth embodiment (embodiment 6) of the present invention will be described.
FIG. 7 is a longitudinal cross-sectional view of the fluid dynamic bearing unit of the sixth embodiment, and parts corresponding to those of the fifth and first embodiments are denoted by the same reference numerals.
As illustrated in FIG. 7, the hydrodynamic bearing unit 1 according to the sixth embodiment has a flanged shaft element 40 in the hydrodynamic bearing unit 1 according to the fifth embodiment as compared with the hydrodynamic bearing unit 1 according to the fifth embodiment (FIG. 5). An annular spacer element 100 is provided to position the second outer ring element 80 with respect to the end plate element 20 in that the flange portion 42 is moved to one end (lower end) of the shaft element 40. Is different. This annular spacer element 100 is disposed so as to surround the flange portion 42 of the flanged shaft element 40.

  Therefore, the hydrodynamic bearing unit 1 of the sixth embodiment is a hydrodynamic bearing unit that supports a flanged shaft element 40 having a flange portion 42 at one end thereof in a relatively rotatable manner, and includes a case element 10, an end plate element 20, The first outer ring element 30 and the second outer ring element 80 inserted into the case element 10 and the flange portion 42 are sandwiched between the lower end surface 82 of the second outer ring element 80 and the upper surface 21 of the end plate element 20. In this way, the flanged shaft element 40 inserted into the first outer ring element 30 and the second outer ring element 80 and the flanged shaft for positioning the second outer ring element 80 relative to the end plate element 20. And an annular spacer element 100 provided so as to surround the flange portion 42 of the element 40.

  Then, a first dynamic pressure is generated on the inner peripheral surface 31 of the first outer ring element 30 so as to receive a radial load between the outer peripheral surface 43 of the main body portion 41 of the opposed shaft element 40 with flange. The dynamic pressure groove 91 is formed, and the inner circumferential surface 81 of the second outer ring element 80 receives a radial load between the opposed outer circumferential surface 43 of the main body portion 41 of the shaft element 40 with flange. A second dynamic pressure groove 92 is formed for generating the second outer ring element 80, and the lower end face 82 of the second outer ring element 80 is axially disposed between the upper face 44 of the flange portion 42 of the opposed flanged shaft element 40. A third dynamic pressure groove 93 for generating a dynamic pressure that receives a load is formed, and an axial surface is formed between the upper surface 21 of the end plate element 20 and the lower surface 45 of the flange portion 42 of the opposed flanged shaft element 40. A fourth dynamic pressure groove 94 for generating a dynamic pressure that receives a load in the direction of the cylinder is formed. The first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and the fourth Lubricating oil is filled in the minute gaps between the opposing surfaces facing the respective dynamic pressure grooves 94.

In the sixth embodiment, the first outer ring element 30, the second outer ring element 80, and the end plate element 20 are made of hardenable steel or hardenable stainless steel material. After the heat treatment and the grinding finish, the first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and the fourth dynamic pressure groove 94 are formed by electrolytic processing. Each is formed.
Since other configurations are not different from those of the fifth embodiment, detailed description thereof is omitted.

  Since the sixth embodiment is configured as described above, the hydrodynamic bearing unit 1 for supporting the flanged shaft element 40 having the flange portion 42 at one end thereof in a relatively rotatable manner is similar to the fifth embodiment. It is easy to modularize each element that constitutes it, that is, the case element 10, the end plate element 20, the first outer ring element 30, the second outer ring element 80, the shaft element 40 with flange, and the spacer element 100. Thus, the standardized hydrodynamic bearing unit 1 can be easily manufactured by using the modularized elements.

  In addition, the radial gap formed by the first outer ring element 30 and the main body 41 of the flanged shaft element 40 and the second outer ring element 80 and the main body 41 of the flanged shaft element 40 are formed. By setting different radial clearances to different dimensions, the dynamic pressure that receives the radial load generated by the dynamic pressure generators formed in the respective clearances can be adjusted to the desired usage conditions. It becomes possible to adjust.

  Further, in the hydrodynamic bearing unit 1 having the same height, the axial height W1 of the first outer ring element 30 and the axial height W2 of the second outer ring element 80 are changed and combined in various ways. A radial gap formed by the outer ring element 30 and the main body 41 of the flanged shaft element 40 and a radial gap formed by the second outer ring element 80 and the main body 41 are formed. It is possible to adjust the dynamic pressure generated by the dynamic pressure generator and receiving the radial load and the dynamic pressure generation position in accordance with the desired usage conditions.

  Further, the axial position of the first outer ring element 30 and the second outer ring element 80 is accurately set with respect to the end plate element 20 according to the flanged shaft element 40 having a different thickness of the flange portion 42 by the spacer element 100. Can be adjusted and set.

The first outer ring element 30, the second outer ring element 80, and the end plate element 20, which are elements in which the dynamic pressure grooves 91 to 94 are formed, are manufactured from a hardenable steel material or a hardenable stainless steel material. Since these dynamic pressure grooves are formed by electrolytic processing after heat treatment and grinding finish, these elements with high hardness and high dimensional accuracy can be obtained, and are hardly scratched. High dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. In addition, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.
In addition, the same effects as those of the fifth embodiment can be obtained.

  In the sixth embodiment, the first to fourth dynamic pressure grooves 91 to 94 include the inner peripheral surface 31 of the first outer ring element 30, the inner peripheral surface 81 of the second outer ring element 80, the second Although formed on the lower end surface 82 of the outer ring element 80 and the upper surface 21 of the end plate element 20, respectively, the outer peripheral surface 43 (upper and lower 2) of the main body portion 41 of the flanged shaft element 40 facing these surfaces is not limited thereto. Part), and may be formed on the upper surface 44 and the lower surface 45 of the flange portion 42 of the shaft element 40 with flange, respectively. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, a seventh embodiment (embodiment 7) of the present invention will be described.
FIG. 8 is a longitudinal sectional view of the hydrodynamic bearing unit of the seventh embodiment. As shown in the figure, the hydrodynamic bearing unit 1 of the seventh embodiment is different from the hydrodynamic bearing unit 1 (FIG. 4) of the fourth embodiment in that the outer ring element 30 and the flange in the hydrodynamic bearing unit 1 of the fourth embodiment. The attached inner ring element 70 is different in that it is divided into two vertically. Alternatively, in the hydrodynamic bearing unit 1 of the fourth embodiment, the axial lengths of the outer ring element 30 and the flanged inner ring element 70 are shortened, and the hydrodynamic bearing unit 1 (see FIG. It can be considered that the combination of the outer ring element 30 and the inner ring element 70 in FIG.

  Thus, the upper part of the outer ring element 30 of the fourth embodiment divided in the upper and lower directions in this way is newly used as the first outer ring element 30, and the inner peripheral surface and the lower end surface thereof have the same reference numerals 31 and 32 as those of the fourth embodiment. , And the lower part is newly set as the second outer ring element 80, and the inner peripheral surface, the lower end surface, and the upper end surface thereof have new reference numerals (however, the same reference numerals as those in the sixth embodiment (FIG. 7)) 81, 82, 83. The upper part of the flanged inner ring element 70 of the fourth embodiment, which is also divided into two vertically, is newly designated as the first inner ring element 70, and the same reference numeral 73 as that of the fourth embodiment is attached to the outer peripheral surface thereof. A new symbol 76 is attached to the lower end surface, and the lower portion is newly set as the second inner ring element 110 with a flange, and the body portion, the flange portion, the outer peripheral surface, the upper surface of the flange portion, the lower surface of the flange portion, and the new reference symbol to the upper end surface. 111, 112, 113, 114, 115, 116 Each subjected, other, elements corresponding to those in Example 4, and subjecting the same reference numerals.

  Therefore, the hydrodynamic bearing unit 1 of the seventh embodiment is a hydrodynamic bearing unit that supports the straight shaft element 40 so as to be relatively rotatable, and is fitted into the case element 10, the end plate element 20, and the case element 10. The first outer ring element 30 and the second outer ring element 80, the first inner ring element 70 inserted into the first outer ring element 30, and the flange portion 112 of the lower end surface 82 and the end of the second outer ring element 80. A flanged second inner ring element 110 having a flange portion 112 at one end inserted into the second outer ring element 80 so as to be sandwiched between the upper surface 21 of the plate element 20, the first inner ring element 70 and the flange And a shaft element 40 fitted into the second inner ring element 110.

  A first dynamic pressure is generated on the inner peripheral surface 31 of the first outer ring element 30 to generate a dynamic pressure that receives a load in the radial direction between the outer peripheral surface 73 of the first inner ring element 70 facing the first outer ring element 30. A groove 91 is formed, and the inner circumferential surface 81 of the second outer ring element 80 receives a radial load between the opposed outer circumferential surface 113 of the main body 111 of the second inner ring element 110 with flange. The second dynamic pressure groove 92 for generating the second outer ring element 80 is formed between the lower end surface 82 of the second outer ring element 80 and the upper surface 114 of the flange portion 112 of the opposed second inner ring element 110 with flange. A third dynamic pressure groove 93 for generating a dynamic pressure that receives a load in the axial direction is formed, and the lower surface of the flange portion 112 of the second inner ring element 110 with flange facing the upper surface 21 of the end plate element 20. Between 115 and Aki A fourth dynamic pressure groove 94 for generating a dynamic pressure that receives a load in the radial direction is formed, and the first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and Lubricating oil is filled in the minute gaps between the opposing surfaces facing the fourth dynamic pressure grooves 94.

  The lower end surface 32 of the first outer ring element 30 and the upper end surface 83 of the second outer ring element 80 come into contact with each other, and the lower end surface 76 of the first inner ring element 70 and the upper end surface 116 of the flanged second inner ring element 110. Are in contact with each other. A lower end surface 46 of the shaft element 40 is slightly floated from the upper surface 21 of the end plate element 20.

In the seventh embodiment, the first outer ring element 30, the second outer ring element 80, and the end plate element 20 are made of hardenable steel or hardenable stainless steel material in the seventh embodiment. After the heat treatment and the grinding finish, the first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and the fourth dynamic pressure groove 94 are formed by electrolytic processing. Each is formed. The first inner ring element 70 and the flanged second inner ring element 110 may be made of the same material.
Since other configurations are not different from those of the fourth embodiment, detailed description thereof is omitted.

  Since the seventh embodiment is configured as described above, the hydrodynamic bearing unit 1 that supports the straight shaft element 40 in a relatively rotatable manner is similar to the fourth embodiment. The case element 10, the end plate element 20, the first outer ring element 30, the second outer ring element 80, the first inner ring element 70, the flanged second inner ring element 110, and the shaft element 40 can be easily modularized. Thus, the standardized hydrodynamic bearing unit 1 can be easily manufactured using the elements thus modularized.

  Further, the radial gap formed by the first outer ring element 30 and the first inner ring element 70 and the main body 111 of the second outer ring element 80 and the flanged second inner ring element 110 are formed. By setting different radial clearances to different dimensions, the dynamic pressure that receives the radial load generated by the dynamic pressure generators formed in the respective clearances can be adjusted to the desired usage conditions. It becomes possible to adjust.

  In the hydrodynamic bearing unit 1 having the same height, the axial height W1 of the first outer ring element 30 and the axial height W2 of the second outer ring element 80 are variously changed, and the first height is adjusted accordingly. A radial formed by the first outer ring element 30 and the first inner ring element 70 by variously changing and combining the axial height of the inner ring element 70 and the axial height of the flanged second inner ring element 110. Radial direction generated by dynamic pressure generating portions respectively formed in the radial gap portion formed by the gap portion in the direction and the radial outer gap element formed by the second outer ring element 80 and the main body portion 111 of the flanged second inner ring element 110. It is possible to adjust the dynamic pressure and the dynamic pressure generation position receiving the load according to the desired usage conditions.

  When adjusting the dynamic pressure and the dynamic pressure generation position in this way, the gap radius formed by the first outer ring element 30 and the first inner ring element 70 (the radius of the virtual cylindrical film formed by the gap center) and By making the gap radius formed by the second outer ring element 80 and the main body 111 of the flanged second inner ring element 110 different, the degree of freedom in adjusting the dynamic pressure can be further expanded. Further, the inner diameter of the first inner ring element 70 and the inner diameter of the flanged second inner ring element 110 are made different, and the shaft element 40 is configured with a stepped shaft element having a large diameter portion and a small diameter portion according to this. (See Examples 8 and 9 to be described later), the outer ring element side and the inner ring element side may be further configured in multiple stages, and the dynamic pressure and dynamic pressure generation position can be set by various combinations of these means. Various adjustments can be made, which makes it possible to quickly meet the design requirements of the optimum bearing for various load forms.

The first outer ring element 30, the second outer ring element 80, and the end plate element 20, which are elements in which the dynamic pressure grooves 91 to 94 are formed, are manufactured from a hardenable steel material or a hardenable stainless steel material. Since these dynamic pressure grooves 91 to 94 are formed by electrolytic processing after heat treatment and grinding finish, it is possible to obtain these elements with high hardness and high dimensional accuracy, and scratches It is difficult to stick and high dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. In addition, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.
In addition, the same effects as in the fourth embodiment can be obtained.

  In the seventh embodiment, the first to fourth dynamic pressure grooves 91 to 94 include the inner peripheral surface 31 of the first outer ring element 30, the inner peripheral surface 81 of the second outer ring element 80, the second Although formed on the lower end surface 82 of the outer ring element 80 and the upper surface 21 of the end plate element 20, respectively, the present invention is not limited to this, and the outer peripheral surface 73 of the first inner ring element 70 facing these surfaces, the second flanged element The inner ring element 110 may be formed on the outer peripheral surface 113 of the main body 111, the upper surface 114 of the flange portion 112 of the flanged second inner ring element 110, and the lower surface 115 thereof. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, an eighth embodiment (Embodiment 8) of the present invention will be described.
FIG. 9 is a longitudinal sectional view of the fluid dynamic bearing unit of the eighth embodiment. As shown in the figure, the hydrodynamic bearing unit 1 of the eighth embodiment is provided with a flange in the hydrodynamic bearing unit 1 of the modification as compared with the modification (FIG. 6) of the hydrodynamic bearing unit 1 of the fifth embodiment. It can be said that the flange portion 42 of the shaft element 40 corresponds to the cut-out portion. Therefore, a new stepped shaft element formed by cutting off the flange portion 42 is given the same reference numeral 40 as in the modification, and its upper half (large diameter portion), lower half (small diameter portion), step portion. Reference numerals 41-1, 41-2, and 48 are newly added to the downward facing surface, and other parts corresponding to the modified example are assigned the same reference numerals.

  The hydrodynamic bearing unit 1 of the eighth embodiment is a hydrodynamic bearing unit that supports a stepped shaft element 40 having an upper half large-diameter portion 41-1 and a lower half small-diameter portion 41-2 in a relatively rotatable manner. A cylindrical case element 10 having a cylindrical inner peripheral surface 11, an end plate element 20 that closes the lower end of the case element 10, and a large-diameter cylindrical inner peripheral surface 31 fitted into the case element 10. The first outer ring element 30 and the second outer ring element 80 having a small-diameter cylindrical inner peripheral surface 81, and the large-diameter portion 41-1 thereof are inserted into the first outer ring element 30, and the small-diameter portion 41-2. Is inserted into the second outer ring element 80, and the first outer ring element 30 and the stepped shaft element 40 inserted into the second outer ring element 80 are provided.

  And the dynamic pressure which receives the load of a radial direction on the internal peripheral surface 31 of the 1st outer ring element 30 between the outer peripheral surfaces 43-1 of the large diameter part 41-1 of the stepped shaft element 40 which opposes is generate | occur | produced. The first dynamic pressure groove 91 is formed, and the inner peripheral surface 81 of the second outer ring element 80 is between the outer peripheral surface 43-2 of the small-diameter portion 41-2 of the opposed stepped shaft element 40. A second dynamic pressure groove 92 for generating a dynamic pressure that receives a radial load is formed on the upper end surface 83 of the second outer ring element 80, and the stepped surface of the stepped shaft element 40 is opposed to the upper end surface 83. A third dynamic pressure groove 93 for generating dynamic pressure that receives a load in the axial direction is formed between the first dynamic pressure groove 91, the second dynamic pressure groove 92, and the third dynamic pressure groove 93. Lubricating oil is filled in the minute gaps between the opposing surfaces facing the pressure grooves 93.

  The lower end surface 32 of the first outer ring element 30 and the upper end surface 83 of the second outer ring element 80 (the portion outside the portion where the third dynamic pressure groove 93 is formed) are in contact with each other, and the second The lower end surface 82 of the outer ring element 80 and the upper surface 21 of the end plate element 20 are in contact with each other. The lower end surface 47 of the stepped shaft element 40 is slightly lifted from the upper surface 21 of the end plate element 20.

In the eighth embodiment, the first outer ring element 30 and the second outer ring element 80 are manufactured from a hardenable steel material or a hardenable stainless steel material in the eighth embodiment. , And after grinding and finishing, a first dynamic pressure groove 91, a second dynamic pressure groove 92, and a third dynamic pressure groove 93 are formed by electrolytic processing. The stepped shaft element 40 may be manufactured from the same material, heat-treated in the same manner, and finished by grinding.
Since the other configuration is not different from the modification of the fifth embodiment (FIG. 6), detailed description is omitted.

  Since the eighth embodiment is configured as described above, the stepped shaft element 40 having the upper-half large-diameter portion 41-1 and the lower-half small-diameter portion 41-2 is supported in a relatively rotatable manner. Similar to the fifth embodiment and its modification, the fluid dynamic bearing unit 1 includes each element constituting the fluid bearing unit 1, that is, a case element 10, an end plate element 20, a first outer ring element 30, a second outer ring element 80, a stage. The attached shaft element 40 can be easily modularized, and the standardized hydrodynamic bearing unit 1 can be easily manufactured using the elements thus modularized.

  Moreover, while changing the outer diameter D1 of the large diameter part 41-1 and the outer diameter D2 of the small diameter part 41-2 of the stepped shaft element 40, the large diameter of the first outer ring element 30 and the stepped shaft element 40 is changed. The radial gap dimension formed by the part 41-1 and the radial gap dimension formed by the second outer ring element 80 and the small diameter part 41-2 of the stepped shaft element 40 are different dimensions. By setting, it becomes possible to adjust the dynamic pressure which receives the load of the radial direction produced | generated in the dynamic pressure generation part formed in each clearance gap according to a desired use condition.

  Further, in the hydrodynamic bearing unit 1 having the same height, the ratio of the axial dimension of the large-diameter portion 41-1 and the axial dimension of the small-diameter portion 41-2 of the stepped shaft element 40 is variously changed. The first outer ring element 30 and the stepped shaft element 40 have a large diameter by variously changing and combining the axial height W1 of the first outer ring element 30 and the axial height W2 of the second outer ring element 80. The dynamic pressure formed in the radial clearance formed by the portion 41-1 and the radial clearance formed by the second outer ring element 80 and the small diameter portion 41-2 of the stepped shaft element 40, respectively. It is possible to adjust the dynamic pressure generated by the generator and receiving the radial load and the dynamic pressure generation position according to the desired usage conditions.

  In addition, this makes it possible to adjust the axial height W2 of the second outer ring element 80 and the axial position of the stepped portion of the stepped shaft element 40, so that the distance between the opposing surfaces that the third dynamic pressure groove 93 faces can be adjusted. The position of the dynamic pressure generating portion formed in the minute gap, in other words, the generation position of the dynamic pressure that receives the axial load acting on the stepped shaft element 40 is the axial direction of the entire rotating body including the rotating side element. Can be adjusted according to the position of the center of gravity, the moment acting in the direction of tilting the stepped shaft element 40 can be reduced, the whirling vibration caused by the gyro moment of the stepped shaft element 40 can be reduced, The relative rotation can be stabilized and the rotation accuracy can be improved.

  Further, a load member (rotating body or fixed body) such as a rotor hub is connected to the outer end portion of the stepped shaft element 40, so that a relatively high bearing rigidity is required. The case element 10 is blocked by the end plate element 20. A large-diameter radial dynamic pressure bearing portion is set on the large-diameter portion 41-1 side of the stepped shaft element 40 located on the opposite side to the side to be mounted, and the case element 10 can be a relatively low bearing rigidity. A small-diameter radial dynamic pressure bearing portion can be set on the small-diameter portion 41-2 side of the stepped shaft element 40 located on the side closed by the element 20, and the friction loss is proportional to the cube of the shaft diameter. In this small-diameter radial dynamic pressure bearing portion, the friction loss can be reduced by the small diameter, and the overall configuration can be achieved while ensuring the required bearing rigidity with a simple configuration. By reducing bearing loss torque, it is possible to reduce power consumption.

  In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of tilting the stepped shaft element 40 can be reduced. From this aspect, the gyro of the stepped shaft element can be reduced. The whirling vibration caused by the moment can be reduced, the relative rotation can be stabilized, and the rotation accuracy can be improved.

  Furthermore, the first outer ring element 30 and the second outer ring element 80, which are elements in which the dynamic pressure grooves 91 to 93 are formed, are manufactured from a hardenable steel material or a hardenable stainless steel material, and are subjected to heat treatment. Since these dynamic pressure grooves 91 to 93 are formed by electrolytic processing after being applied and finished by grinding, these elements having high hardness and high dimensional accuracy can be obtained and scratched. It is difficult to maintain a high dimensional accuracy. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. Moreover, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.

  In addition, the eighth embodiment can achieve the same effects as the modification of the fifth embodiment (FIG. 6). However, the hydrodynamic bearing unit 1 of the eighth embodiment has an action of constantly pressing the shaft element 40 in the axial direction toward the end plate element 20 by a bias effect such as magnetic force acting between the rotation side element and the fixed side element. This fluid bearing unit is suitable for use in the case where it can be expected. In this respect, the operation and effect are different from those of the modified example.

  In the eighth embodiment, the first to third dynamic pressure grooves 91 to 93 include the inner peripheral surface 31 of the first outer ring element 30, the inner peripheral surface 81 of the second outer ring element 80, the second Although formed in the upper end surface 83 of the outer ring element 80, respectively, it is not limited to this, The outer peripheral surface 43-1 of the large diameter part 41-1 of the stepped shaft element 40 which opposes these surfaces, and the same small diameter part 41- 2 may be formed on the outer peripheral surface 43-2 and the stepped surface 48, respectively. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, a ninth embodiment (embodiment 9) of the present invention will be described.
FIG. 10 is a longitudinal sectional view of the fluid dynamic bearing unit of the ninth embodiment. As shown in the figure, the hydrodynamic bearing unit 1 of the ninth embodiment is different from the hydrodynamic bearing unit 1 of the eighth embodiment (FIG. 9) in the upper half and the lower half of the stepped shaft element 40. The magnitude relationship of each diameter is reversed. Therefore, the upper-half large-diameter portion 41-1 and the lower-half small-diameter portion 41-2 in the hydrodynamic bearing unit 1 of the eighth embodiment are the upper-half small-diameter portion 41-1 and the lower-half large-diameter portion in the ninth embodiment. The diameter portion is 41-2. Correspondingly, the size relationship between the diameters of the cylindrical inner peripheral surfaces of the first outer ring element 30 and the second outer ring element 80 is also reversed. The surface of the step portion of the stepped shaft element 40 is upward, and a reference numeral 49 is newly added to the surface, but other parts corresponding to those in the eighth embodiment are assigned the same reference numerals. .

  Therefore, the hydrodynamic bearing unit 1 of the ninth embodiment is a hydrodynamic bearing unit that rotatably supports the stepped shaft element 40 having the upper half small-diameter portion 41-1 and the lower half large-diameter portion 41-2. A cylindrical case element 10 having a cylindrical inner peripheral surface 11, an end plate element 20 that closes the lower end of the case element 10, and a small-diameter cylindrical inner peripheral surface 31 that is fitted into the case element 10. The first outer ring element 30 and the second outer ring element 80 having a large-diameter cylindrical inner peripheral surface 81 and the small diameter part 41-1 thereof are inserted into the first outer ring element 30, and the large diameter part 41- 2 includes a first outer ring element 30 and a stepped shaft element 40 inserted into the second outer ring element 80 so that the second outer ring element 80 is inserted.

  And the dynamic pressure which receives the load of a radial direction is generated in the inner peripheral surface 31 of the 1st outer ring element 30 between the outer peripheral surfaces 43-1 of the small diameter part 41-1 of the stepped shaft element 40 which opposes. The first dynamic pressure groove 91 is formed, and the inner peripheral surface 81 of the second outer ring element 80 is between the outer peripheral surface 43-2 of the large-diameter portion 41-2 of the opposed stepped shaft element 40. A second dynamic pressure groove 92 for generating a dynamic pressure that receives a load in the radial direction is formed on the lower end surface 32 of the first outer ring element 30. 49, a third dynamic pressure groove 93 for generating a dynamic pressure that receives an axial load is formed, and the lower surface 47 of the opposed stepped shaft element 40 is formed on the upper surface 21 of the end plate element 20. Generates dynamic pressure that receives axial load. A fourth dynamic pressure groove 94 is formed, and the first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and the fourth dynamic pressure groove 94 face each other. Lubricating oil is filled in the minute gaps between the opposing surfaces.

  The lower end surface 32 of the first outer ring element 30 (the portion outside the portion where the third dynamic pressure groove 93 is formed) and the upper end surface 83 of the second outer ring element 80 are in contact with each other. The lower end surface 82 and the upper surface 21 of the end plate element 20 are in contact with each other.

In the ninth embodiment, the first outer ring element 30, the second outer ring element 80 and the end plate element 20 are manufactured from a hardenable steel material or a hardenable stainless steel material. The first dynamic pressure groove 91, the second dynamic pressure groove 92, the third dynamic pressure groove 93, and the fourth dynamic pressure are obtained by electrolytic processing after being subjected to heat treatment and ground. Each groove 94 is formed. The stepped shaft element 40 may be manufactured from the same material, heat-treated in the same manner, and finished by grinding.
Since other configurations are not different from those of the eighth embodiment, detailed description thereof is omitted.

  Since the ninth embodiment is configured as described above, the stepped shaft element 40 having the upper half small-diameter portion 41-1 and the lower half large-diameter portion 41-2 is supported in a relatively rotatable manner. Similar to the eighth embodiment, the fluid dynamic bearing unit 1 is configured by each element constituting the fluid bearing unit 1, that is, the case element 10, the end plate element 20, the first outer ring element 30, the second outer ring element 80, and the stepped shaft element 40. Can be easily modularized, and the standardized hydrodynamic bearing unit 1 can be easily manufactured using the elements thus modularized.

  Further, the outer diameter dimension D1 of the small diameter part 41-1 of the stepped shaft element 40 and the outer diameter dimension D2 of the large diameter part 41-2 are changed, and the first outer ring element 30 and the small diameter part of the stepped shaft element 40 are changed. The radial clearance dimension formed by 41-1 and the radial clearance dimension formed by the second outer ring element 80 and the large diameter portion 41-2 of the stepped shaft element 40 are set to different dimensions. By setting, it becomes possible to adjust the dynamic pressure which receives the load of the radial direction produced | generated in the dynamic pressure generation part formed in each clearance gap according to a desired use condition.

  Moreover, in the hydrodynamic bearing unit 1 of the same height, the ratio of the axial dimension of the small diameter part 41-1 and the axial dimension of the large diameter part 41-2 of the stepped shaft element 40 is variously changed, and the first A small diameter portion of the first outer ring element 30 and the stepped shaft element 40 by variously changing and combining the axial height W1 of the first outer ring element 30 and the axial height W2 of the second outer ring element 80. 41-1 and the radial clearance formed by the second outer ring element 80 and the radial clearance formed by the large-diameter portion 41-2 of the stepped shaft element 40, respectively. It is possible to adjust the dynamic pressure generated by the generator and receiving the radial load and the dynamic pressure generation position according to the desired usage conditions.

  Further, this allows the axial height of the first outer ring element 30 and the axial position of the stepped portion of the stepped shaft element 40 to be adjusted, so that the space between the opposing surfaces facing the third dynamic pressure groove 93 can be adjusted. The position of the dynamic pressure generating portion formed in the minute gap, in other words, the generation position of the dynamic pressure that receives the axial load acting on the stepped shaft element 40 is determined in the axial direction of the entire rotating body including the rotating side element. It can be adjusted to the position of the center of gravity, the moment acting in the direction of tilting the stepped shaft element 40 can be reduced, the whirling vibration caused by the gyro moment of the stepped shaft element 40 can be reduced, and the relative The rotation can be stabilized and the rotation accuracy can be improved.

  Further, in the small-diameter radial dynamic pressure bearing portion that is set on the small-diameter portion 41-1 side of the stepped shaft element 40 and is formed in a minute gap between the opposing surfaces facing the first dynamic pressure groove 91, the small-diameter radial dynamic pressure bearing portion has a small diameter. Accordingly, the friction loss can be reduced, so that the shaft loss torque can be reduced and the power consumption can be reduced.

  In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of depressing the stepped shaft element 40 can be reduced. The whirling vibration caused by the gyro moment can be reduced, the relative rotation can be stabilized, and the rotation accuracy can be improved.

  The first outer ring element 30, the second outer ring element 80, and the end plate element 20, which are elements in which the dynamic pressure grooves 91 to 94 are formed, are manufactured from a hardenable steel material or a hardenable stainless steel material. Since these dynamic pressure grooves 91 to 94 are formed by electrolytic processing after heat treatment and grinding finish, it is possible to obtain these elements having high hardness and high dimensional accuracy. It is difficult to be damaged, and high dimensional accuracy can be maintained. In particular, a dynamic pressure groove having a fine surface roughness can be obtained and the shape thereof is maintained, so that the dynamic pressure bearing function as designed can be exhibited. Moreover, the machining time for forming the dynamic pressure grooves can be shortened by electrolytic machining.

Furthermore, even when the stepped shaft element 40 cannot be expected to always be pressed in the axial direction toward the end plate element 20 due to a bias effect such as a magnetic force acting between the rotating side element and the fixed side element, The dynamic pressure generated in the dynamic pressure generating portion formed in the minute gap between the facing surfaces facing the third dynamic pressure groove 93 can exert an equivalent action, whereby the third dynamic pressure groove The minute gap between the facing surfaces facing 93 and the minute gap between the facing surfaces facing the fourth dynamic pressure groove 94 are both kept at an appropriate gap to stabilize the relative rotation of the stepped shaft element 40 and to rotate the rotation accuracy. Can be improved.
In addition, the same effects as in Example 8 can be achieved.

  In the ninth embodiment, the first to fourth dynamic pressure grooves 91 to 94 include the inner peripheral surface 31 of the first outer ring element 30, the inner peripheral surface 81 of the second outer ring element 80, and the first Although formed on the lower end surface 32 of the outer ring element 30 and the upper surface 21 of the end plate element 20, respectively, the outer peripheral surface 43- of the small-diameter portion 41-1 of the stepped shaft element 40 opposed to these surfaces is not limited thereto. 1 may be formed on the outer peripheral surface 43-2 of the large-diameter portion 41-2, the surface 49 of the step portion, and the lower end surface 47, respectively. In this case as well, the element in which the dynamic pressure grooves are formed is manufactured from a hardenable steel material or a hardenable stainless steel material, subjected to heat treatment, ground, and then subjected to electrolytic processing. A groove is formed. Even if it does in this way, there can exist an effect similar to the above.

Next, an application example of the hydrodynamic bearing unit 1 of the present embodiment will be described.
FIG. 11 is a longitudinal sectional view of a spindle motor to which the hydrodynamic bearing unit 1 of the first embodiment (FIG. 1) is applied. In the figure, the spindle motor 120 has a case element 10 of the fluid dynamic bearing unit 1 fitted in a central circular hole formed through the boss 126 of the housing 121, and constitutes a shaft rotation type spindle motor. ing. The boss portion 126 is formed so as to protrude upward from the bottom portion at a substantially central position in FIG. 11 of the bottom portion of the housing 121. A boss portion of a rotor hub 122 constituting a rotating element of the motor is fitted to an upper end portion of a main body portion (shaft portion) 41 of the shaft element 40 of the fluid dynamic bearing unit 1, and the rotor hub 122 is connected to the shaft element 40. Rotates together. On the outer peripheral surface of the rotor hub 122, information recording media (recording disks) such as magnetic disks and optical disks (not shown) are mounted in a plurality of stages. Although not shown in detail in the upper end of the main body 41, a tap hole is formed, and a clamp member that presses and fixes these information recording media from above is screwed to the tap hole. Thus, the main body 41 is fixed.

  A stator 123 formed by winding a coil around a stator core is fitted to the outer peripheral surface of the boss portion 126 of the housing 121, and a permanent magnet fitted to the shield yoke with a slight radial gap therebetween. 124 is arranged in a circumferential direction so as to surround the stator 123, and is attached to the inner peripheral surface of the peripheral wall of the rotor hub 122. A flexible wiring board 125 is fixed to the lower surface of the housing 121, and a control current is supplied to the stator 123 from the output end of the wiring board 125, thereby comprising a permanent magnet 124, a rotor hub 122, a shaft element 40, and the like. The rotor assembly begins to rotate relative to the stator 123.

  As in the second embodiment (FIG. 2), when the dynamic pressure groove for generating the dynamic pressure that receives the load in the axial direction is only the second dynamic pressure groove 52, the fluid dynamic bearing of the second embodiment. In the spindle motor 120 to which the unit 1 is applied, in order to receive a load acting in a direction opposite to the direction of the load supported by the dynamic pressure generated by the second dynamic pressure groove 52. Although not shown, an annular suction plate is fixed to the bottom surface of the housing 121 immediately below the permanent magnet 124. In this way, the annular suction plate acts to attract the permanent magnet 124, so that the rotor assembly is stably supported by bearing in balance with the dynamic pressure generated by the second dynamic pressure groove 52. be able to. The same applies to Example 8 (FIG. 9).

FIG. 12 is a longitudinal cross-sectional view of a magnetic disk drive device including a spindle motor 120 to which the hydrodynamic bearing unit 1 of the first embodiment is applied.
As shown in FIG. 12, the magnetic disk drive device 130 includes a spindle motor 120, a housing 121, and a cover member 131 that seals the inside of the housing 121 to form a clean space with extremely little dust. The magnetic disk 132, the clamp member 133 of the magnetic disk 132, the recording head 134 for writing and / or reading information to and from the magnetic disk 132, the arm 135 supporting the recording head 134, the recording head 134, and The voice coil motor 136 moves the arm 135 to a required position. One magnetic disk 132 is mounted on the rotor hub 122, but the number of magnetic disks 132 is not limited to this. The magnetic disk 132 rotates with the rotation of the rotor hub 122.

  The recording heads 134 are mounted in a pair of upper and lower positions on the tip of a head stack assembly fixed to an arm 135 that is pivotally supported at an appropriate position on the bottom of the housing 121. The pair of upper and lower recording heads 134 are arranged so as to sandwich one magnetic disk 132 so that information is written to and / or read from both surfaces of the magnetic disk 132. Since the magnetic disk drive device 130 has a single magnetic disk 132, only one pair of upper and lower recording heads 134 is provided as described above. However, when there are a plurality of magnetic disks 132, A pair of recording heads 134 are provided for each disk.

The second to ninth embodiments and their modifications can also be applied to the spindle motor in the same manner as described above, and the spindle motor thus configured can be further applied to a magnetic disk drive. It is possible to apply.

  As described above, the fluid bearing unit 1 of the present embodiment is applied as the fluid bearing of the spindle motor 120, and the spindle motor 120 thus obtained is applied to the magnetic disk drive device 130, thereby obtaining a desired structure, Procurement of a standardized hydrodynamic bearing unit 1 with bearing performance and mass production of a spindle motor having high rotational accuracy and high reliability and a magnetic disk drive having the spindle motor at low cost It becomes possible.

  In the above example, the spindle motor 120 including the hydrodynamic bearing unit 1 of the present embodiment is applied to the magnetic disk drive device 130. However, the spindle motor including the hydrodynamic bearing unit 1 of the present embodiment may be a CD or a The present invention may be applied to a recording disk drive device that drives a recording disk such as a DVD.

The invention of the present application is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the eighth and ninth embodiments, the step portion of the stepped shaft element 40 (the portion that transitions from the large diameter portion to the small diameter portion) can be tapered.

It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 1. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 2. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 3. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 4. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 5. FIG. 10 is a longitudinal sectional view of a modification of the fluid dynamic bearing unit of the fifth embodiment. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 6. FIG. 10 is a longitudinal sectional view of a fluid dynamic bearing unit of Example 7. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 8. It is a longitudinal cross-sectional view of the hydrodynamic bearing unit of Example 9. It is a longitudinal cross-sectional view of the spindle motor to which the fluid dynamic bearing unit of Example 1 is applied. It is a longitudinal cross-sectional view of the magnetic disk drive device provided with the spindle motor to which the hydrodynamic bearing unit of Example 1 was applied. It is a longitudinal cross-sectional view of a spindle motor to which a conventional hydrodynamic bearing device is applied.

DESCRIPTION OF SYMBOLS 1 ... Fluid bearing unit, 10 ... Case element, 11 ... Inner peripheral surface, 12 ... Step part, 20 ... End plate element, 21 ... Upper surface, 30 ... Outer ring element, 1st outer ring element, 31 ... Inner peripheral surface , 32 ... lower end surface, 40 ... shaft element (straight, with one end flange, with intermediate flange, stepped), 41 ... main body, 41-1 ... one half (upper half, large diameter or small diameter) 41-2 ... other half (lower half, small diameter or large diameter), 42 ... flange, 43 ... outer peripheral surface, 43-1 ... upper outer peripheral surface, 43-2 ... lower outer peripheral surface, 144 ... upper surface 45, lower surface, 46, 47 ... lower end surface, 48, 49 ... stepped surface, 51 (51-1, 51-2) ... first dynamic pressure groove, 52 ... second dynamic pressure groove, 53 ... Third dynamic pressure groove, 54... Fourth dynamic pressure groove, 60... Seal mechanism, 70... Inner ring element, flanged inner ring element, first. Inner ring element, 71 ... body part, 72 ... flange part, 73 ... outer peripheral surface, 74 ... upper surface, 75 ... lower surface, 76 ... lower end surface, 80 ... second outer ring element, 81 ... inner peripheral surface, 82 ... lower end surface 83 ... Upper end surface, 91 ... First dynamic pressure groove, 92 ... Second dynamic pressure groove, 93 ... Third dynamic pressure groove, 94 ... Fourth dynamic pressure groove, 100 ... Spacer element, 110 ... Flange Included second inner ring element 111... Body portion 112. Flange portion 113. Outer peripheral surface 114. Upper surface 115. Lower surface 116. Upper end surface 120 spindle motor 121 121 housing 122 rotor hub 123 Stator, 124 ... permanent magnet, 125 ... wiring board, 126 ... boss, 130 ... magnetic disk drive, 131 ... cover member, 132 ... magnetic disk, 133 ... clamp member, 134 ... recording head, 135 ... arm, 13 ... voice coil motor, F ... weight of the entire rotating part, Q ... center of gravity of the whole rotating part, R ... axis lowest point of the rotation axis, T ... resultant force of the axial direction of the dynamic pressure.

Claims (7)

A hydrodynamic bearing unit that is configured by combining a plurality of modularized elements, and has a plurality of dynamic pressure generating mechanism portions therein and a flanged shaft element having a flange portion at one end thereof for relative rotation. ,
A cylindrical case element having a cylindrical inner peripheral surface;
An end plate element for closing the lower end of the case element;
An outer ring element fitted into the case element;
A flanged shaft element inserted into the outer ring element so that the flange portion is sandwiched between the lower end surface of the outer ring element and the upper surface of the end plate element;
On the inner peripheral surface of the outer ring element or the outer peripheral surface of the main body of the flanged shaft element,
A first dynamic pressure groove for generating a dynamic pressure that receives a radial load is formed between the opposing surfaces.
On the lower end surface of the outer ring element or the upper surface of the flange portion of the flanged shaft element, a second dynamic pressure groove for generating a dynamic pressure that receives a load in the axial direction is formed between the opposing surfaces.
On the upper surface of the end plate element or the lower surface of the flange portion of the flanged shaft element, a third dynamic pressure groove for generating a dynamic pressure that receives a load in the axial direction is formed between both the opposed surfaces.
Lubricating oil is filled in the minute gaps between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove,
At least the case element, the end plate element, and the flanged shaft element are finished with high precision, and the hydrodynamic bearing unit is fitted and fitted to a mating member to which the fluid bearing unit is assembled with high precision.
The element in which any one of the first to third dynamic pressure grooves is formed on any surface thereof is made of hardenable steel or hardenable stainless steel, and is subjected to a heat treatment and ground. Then, in the electrolytic processing, the dynamic pressure groove is formed,
Of the plurality of elements, the joint surfaces or sliding surfaces between both adjacent elements are all parallel to or orthogonal to the axial direction of the flanged shaft element. A hydrodynamic bearing unit. 2. The hydrodynamic bearing unit according to claim 1, wherein the first dynamic pressure groove is formed at two upper and lower portions separated in an axial direction of an element having a surface on which the dynamic pressure groove is formed. . A hydrodynamic bearing unit that is configured by combining a plurality of modularized elements, and has a plurality of dynamic pressure generating mechanism portions therein and a flanged shaft element having a flange portion at one end thereof for relative rotation. ,
A cylindrical case element having a cylindrical inner peripheral surface;
An end plate element for closing the lower end of the case element;
A first outer ring element and a second outer ring element fitted into the case element;
A flanged shaft element inserted into the first outer ring element and the second outer ring element so that the flange portion is sandwiched between the lower end surface of the second outer ring element and the upper surface of the end plate element; ,
An annular spacer element provided so as to surround a flange portion of the flanged shaft element in order to position the second outer ring element with respect to the end plate element;
A first dynamic pressure is generated on the inner peripheral surface of the first outer ring element or the outer peripheral surface of the main body portion of the flanged shaft element to receive a radial load between the opposing surfaces.
Dynamic pressure grooves are formed,
On the inner peripheral surface of the second outer ring element or the outer peripheral surface of the main body portion of the flanged shaft element, a second dynamic pressure is generated to generate a radial load between the opposing surfaces.
Dynamic pressure grooves are formed,
On the lower end surface of the second outer ring element or the upper surface of the flange portion of the flanged shaft element, a third dynamic pressure groove for generating a dynamic pressure that receives a load in the axial direction is formed between the opposing surfaces. And
On the upper surface of the end plate element or the lower surface of the flange portion of the flanged shaft element, a fourth dynamic pressure groove for generating a dynamic pressure to receive a load in the axial direction is formed between the opposing surfaces.
Lubricating oil is filled in the minute gaps between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, the third dynamic pressure groove, and the fourth dynamic pressure groove,
At least the case element, the end plate element, and the flanged shaft element are finished with high precision, and the hydrodynamic bearing unit is fitted and fitted to a mating member to which the fluid bearing unit is assembled with high precision.
The element in which any one of the first to fourth dynamic pressure grooves is formed on either surface is made of hardenable steel or hardenable stainless steel, and is subjected to heat treatment and ground. Then, in the electrolytic processing, the dynamic pressure groove is formed,
Of the plurality of elements, the joint surfaces or sliding surfaces between both adjacent elements are all parallel to or orthogonal to the axial direction of the flanged shaft element. A hydrodynamic bearing unit. The stepped portion to the lower portion of the case elements are formed, said end plate element, is fitted on the stepped portion, of claims 1 to 3, characterized in that closes the lower end of the casing element The fluid dynamic bearing unit according to any one of the above. Fluid bearing according to any one of claims 1 to 4 the lower end of the casing element bearing container constructed is closed by the end plate element, characterized in that it is formed by integral molding of the same material unit. A spindle motor having a hydrodynamic bearing unit according to claim 1 or 3, a stator fixed to the housing,
A rotor hub that forms a rotating element fitted to the upper end of the flanged shaft element ; and a rotor magnet that is fitted to the rotor hub and generates a rotating magnetic field in cooperation with the stator. And a rotor provided rotatably,
The spindle motor characterized in that the hydrodynamic bearing unit supports the rotation of the rotor. A recording disk drive comprising the spindle motor according to claim 6 ,
A recording head for writing and / or reading information on a recording disk;
A recording disk drive apparatus, wherein the spindle motor rotates the recording disk.

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