JP2007139199A - Dynamical pressure fluid bearing device and motor comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify structures of a dynamical pressure fluid bearing device and a motor using the same, and to prevent leakage of lubrication fluid. <P>SOLUTION: This dynamical pressure bearing device comprises a shaft member 24 having a shaft portion 28 and a flange portion 32, and a sleeve member 26 relatively rotatable to the shaft member 24. A radial dynamical pressure bearing is constituted in a clearance between an outer peripheral face of the shaft portion 28 and an inner peripheral face of the sleeve member 26, and a thrust dynamical pressure bearing is constituted in a clearance between one face of the flange portion 32 and a first opposed face of the sleeve member 26. The lubrication fluid is continuously supplied to the clearance of the radial dynamical pressure bearing and the clearance of the thrust dynamical pressure bearing connected therewith without interruption, and the lubrication fluid forms an interface only at the other end side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention utilizes a fluid made of lubricating oil (referred to as “lubricating fluid”), generates pressure on the lubricating fluid filled between the shaft member and the sleeve member during relative rotation, and supports the shaft member by the fluid pressure. The present invention relates to a hydrodynamic fluid bearing device and a motor including the same.

  Conventionally, as a hydrodynamic bearing device, a shaft member having a shaft portion and a flange portion projecting radially outward from the shaft portion, a sleeve member that is rotatable relative to the shaft member, and a shaft A device having a lubricating fluid filled in a space defined between a member and a sleeve member is known. In this type of hydrodynamic bearing device, a radial dynamic pressure groove is provided on one or both of the outer peripheral surface of the shaft portion of the shaft member and the inner peripheral surface of the sleeve member facing the shaft member. The gap between the inner peripheral surface of the sleeve member is filled with a lubricating fluid. Also, a thrust dynamic pressure fluid groove is provided on one or both of both surfaces of the flange portion of the shaft member and the inner surface of the sleeve member facing the both surfaces, and the gap between both surfaces of the flange portion and the inner surface of the sleeve member is lubricated. Filled with fluid.

  Such a hydrodynamic fluid bearing device is often used for various motors such as a DC brushless motor for driving a hard disk of a microcomputer or a CD-ROM driving motor. And one of the sleeve members is coupled to the stator and the fixed portion of the motor, and the other is coupled to the rotor. In addition, motors include a fixed shaft type in which the shaft is fixed and the rotor rotates relative to it, and a rotary shaft type in which the shaft rotates together with the rotor. In the fixed shaft type, the shaft is like the base plate of the motor. The sleeve member is fixed to the fixed portion and is coupled to the rotor so as to rotate integrally. In the shaft rotation type, the sleeve member is fixed to the fixing portion of the motor, and the shaft member is connected to the rotor.

JP-A-8-163820

  In such a hydrodynamic bearing device and a motor including the same, it is an important problem to maintain the lubricating fluid filled in the gap between the shaft member and the sleeve member. That is, the lubricating fluid may thermally expand at a high temperature and overflow from the gap, evaporate, scatter by impact, or leak to the outside due to bleeding known as migration.

  An object of the present invention is to simplify the structure of a fluid dynamic pressure bearing device and a motor using the same, and to prevent leakage of a lubricating fluid.

Claim 1 of the present invention is a shaft member comprising: a shaft portion; and a disc-shaped flange portion that is formed integrally with or separate from the shaft portion and projects radially outward from the shaft portion;
A small inner diameter portion opposed to the outer peripheral surface of the shaft portion and an inner diameter portion larger than the small inner diameter portion and opposed to the outer peripheral surface of the flange portion, one end side being closed and the other end side being open, surrounding the flange portion and the shaft A sleeve member rotatable relative to the member;
A radial dynamic pressure bearing formed in a gap between the outer peripheral surface of the shaft portion and the inner peripheral surface of the small inner diameter portion and having a radial dynamic pressure groove for inducing dynamic pressure in the lubricating fluid held in the gap during relative rotation; ,
Thrust motion having a thrust dynamic pressure groove formed in a gap between one surface of the flange portion and the first facing surface of the sleeve member facing the flange portion and inducing dynamic pressure in the lubricating fluid held in the gap during relative rotation Pressure bearings,
And a lubricating fluid that fills the gap of the radial dynamic pressure bearing and the gap of the thrust dynamic pressure bearing continuous therewith without interruption and forms an interface only on the other end side. According to a second aspect of the present invention, on the other end side from the thrust dynamic pressure bearing, a taper seal is formed between the shaft member and the sleeve member so that the gap size decreases toward the thrust dynamic pressure bearing,
The interface is characterized by being located within the taper seal.

According to a third aspect of the present invention, the flange portion is surrounded by the sleeve member,
In the gap between the other surface of the flange portion and the second opposite surface of the sleeve member facing the other surface, a taper seal is formed in which the gap size decreases from the radially inner side to the outer side,
The interface is characterized by being located in the gap where the taper seal is formed.

According to a fourth aspect of the present invention, the sleeve member includes a sleeve member main body having a small inner diameter portion and an inner diameter portion facing the outer peripheral surface of the flange portion, a lid portion closing the inner diameter portion facing the outer peripheral surface of the flange portion, With
The inner peripheral surface of the lid portion is located radially inward from the outer peripheral surface of the flange portion, thereby preventing any one of the shaft member and the sleeve member from slipping out of the other during relative rotation.

According to claim 5 of the present invention, the sleeve member includes a large inner diameter portion that is located on the other end side and is larger in diameter than the inner diameter portion facing the outer peripheral surface of the flange portion,
The lid part is fixed to the inner peripheral surface of the large inner diameter part.

  A sixth aspect of the present invention is characterized in that the shaft member or the sleeve member is urged by a magnetic force in a direction opposite to the thrust support force generated by the thrust dynamic pressure bearing.

According to a seventh aspect of the present invention, the gap between one end portion of the shaft portion and the facing portion of the sleeve member facing the one end portion and the radially outer end portion of the thrust dynamic pressure bearing are filled with a lubricating fluid. Through the pressure adjustment hole,
The lubricating fluid circulates through the pressure adjusting hole, the thrust dynamic pressure bearing, and the radial dynamic pressure bearing.

  An eighth aspect of the present invention is characterized in that an oil repellent is applied to a portion near the interface of the shaft member.

Claim 9 of the present invention provides either a shaft member or a sleeve member, and a fixing portion comprising a stator,
A rotor including the other of the shaft member and the sleeve member and a rotor magnet facing the stator;
A fluid dynamic pressure bearing device according to any one of claims 1 to 8.

Claim 10 of the present invention comprises: a fixing portion;
A rotor facing the fixed part;
A thrust dynamic pressure bearing having a thrust dynamic pressure groove formed in a gap between the fixed portion and the rotor and inducing a dynamic pressure in the lubricating fluid held in the gap during relative rotation;
A taper seal that is formed in the gap between the fixed portion and the rotor, is connected to the thrust dynamic pressure bearing, and decreases in the gap dimension toward the thrust dynamic pressure bearing;
A lubricating fluid that is continuously filled in the thrust dynamic pressure bearing and the taper seal and forms an interface in the taper seal;
It is located in the site | part which forms the gap | interval from a thrust dynamic pressure bearing of a rotation part or a rotor to a taper seal, and is equipped with the throttle protrusion which protrudes from a site | part and reduces a gap | interval dimension.

According to claim 11 of the present invention, the fixing portion is
A shaft member comprising: a shaft portion; and a disc-shaped flange portion that is configured integrally or separately from the shaft portion and protrudes radially outward from the shaft portion;
A small inner diameter portion that opposes the outer peripheral surface of the shaft portion and an inner diameter portion that is larger in diameter than the small inner diameter portion and that faces the outer peripheral surface of the flange portion. A sleeve member relatively rotatable with respect to the rotor, and the rotor includes the other,
A radial dynamic pressure bearing having a radial dynamic pressure groove for inducing dynamic pressure in the lubricating fluid held in the gap during relative rotation is formed in the gap between the outer peripheral surface of the shaft portion and the inner peripheral surface of the small inner diameter portion. And
The thrust dynamic pressure bearing is formed in a gap between one surface of the flange portion and the first facing surface of the sleeve member facing the flange portion,
Lubricating fluid is continuously filled in the gap constituting the radial dynamic pressure bearing and the gap constituting the thrust dynamic pressure bearing without interruption, and the interface is formed only within the taper seal. To do.

  In the present invention, the structure of the hydrodynamic bearing device and the motor using the same can be simplified, and the possibility of leakage of the lubricating fluid is reduced.

  Further, stable rotation of the rotor can be obtained.

  FIG. 1 shows an embodiment in which a hydrodynamic bearing device according to the present invention is used in a DC brushless spindle motor for driving a hard disk of a microcomputer. In FIG. 1, the illustrated spindle motor includes a base plate 2. The base plate 2 has a circular plate body 4, and a peripheral side wall 6 extending upward is provided on the outer periphery of the plate body 4, and the outer end of the peripheral side wall 6 is attached to project outward in the radial direction. A flange 8 is provided. Although not shown, the mounting flange 8 is attached to a base member of a disk drive device such as a hard disk drive device by a fixing screw. A rotor 10 is rotatably supported on the base plate 2 via a hydrodynamic bearing device 11. The rotor 10 includes a cylindrical hub body 12. At the lower end of the hub body 12, there is provided a disk mounting portion 14 that protrudes outward in the radial direction, and a plurality of recording disks such as magnetic disks are attached to the disk mounting portion 14 at a predetermined interval. A rotor magnet 16 is attached to the inner peripheral surface of the hub body 12, and a stator 18 is disposed on the base plate 2 so as to face the rotor magnet 16. The stator 18 includes a stator core 20 in which a plurality of core plates are stacked, and a coil 22 wound around the stator core 20. Thus, when the current is supplied to the coil 22 of the stator 18, the rotor 10 is rotationally driven in a predetermined direction by the mutual magnetic action of the stator 18 and the magnet 16.

  Next, the dynamic pressure fluid bearing device 11 will be described. The illustrated dynamic pressure fluid bearing device 11 includes a combination of a shaft member 24 and a sleeve member 26. The shaft member 24 has an elongated shaft portion 28 having a circular cross section, and a disk-shaped member 30 is integrally provided in the vicinity of the other end portion of the shaft portion 28, and the disk-shaped member 30 extends in the radial direction from the shaft portion 28. A flange portion 32 protruding outward is formed. In the embodiment, the shaft portion 28 and the disk-shaped member 30 are integrally formed, but they may be formed separately and fixed. The rotor 12 is fixed to the other end protruding beyond the flange portion 32 of the shaft portion 28 of the shaft member 24 by means such as press fitting. Accordingly, the shaft member 24 is fixed to the rotor 10 and rotated in a predetermined direction integrally with the rotor 12 with respect to the base plate 2.

  The shaft portion 28 of the shaft member 24 is formed with an injection hole 34 extending from one end (lower end) to the upper end. In the embodiment, one end of the injection hole 34 opens at the lower end surface of the shaft portion 28, the other end opens at the upper end surface of the shaft portion 28, and extends linearly in the axial direction from the one end opening to the other end opening. Yes. A tapered portion 34a having a small diameter in the injection direction of the lubricating fluid such as oil is provided at the upper end in the axial direction of the injection hole 34, and the inner diameter of the injection hole 34 is increased above the tapered portion 34a. The inner diameter of the injection hole 34 is somewhat smaller on the lower side. The filling of the lubricating fluid through the injection hole 34 will be described later.

  The sleeve member 26 includes a hollow cylindrical sleeve member main body 36. The sleeve member main body 36 has a small inner diameter portion 38 having a small inner diameter, a medium inner diameter portion 40 having an inner diameter larger than the small inner diameter portion 38, and a large inner diameter portion 42 having an inner diameter larger than the medium inner diameter portion 40. The medium inner diameter portion 40 and the large inner diameter portion 42 are disposed in this order from one end portion (lower end portion) of the sleeve member main body 36 toward the other end portion (upper end portion). The inner diameter of the small inner diameter portion 38 is set somewhat larger than the outer diameter of the shaft portion 28 of the shaft member 24, and the inner diameter of the medium inner diameter portion 40 is set somewhat larger than the outer diameter of the flange portion 32 of the shaft member 24. . When the shaft member 28 is attached to such a sleeve member main body 36, the shaft portion 28 of the shaft member 24 is fitted into the small inner diameter portion 38 of the sleeve member main body 36 (fitting in a relatively long region in the axial direction of the shaft member 24). In addition, the flange portion 30 of the shaft member 24 is disposed on the inner diameter portion 40 of the sleeve member main body 36, and the small inner diameter portion 38, the shoulder portion 46, and the medium inner diameter portion 40 of the sleeve member main body 36 are connected to the shaft. A gap for the lubricating fluid is provided between the shaft portion 28 of the member 24 and one surface and the peripheral surface of the flange portion 32.

  The cap member 44 is attached and fixed to the large inner diameter portion of the sleeve member main body 36 so as to rotate integrally with the sleeve member main body 36, and forms a part of the sleeve member main body 36. The cap member 44 covers the outer surface of the flange portion 32 of the shaft member 24, and includes a middle inner diameter portion 40 of the sleeve member main body 36, and a shoulder portion 46 that defines the boundary between the inner inner diameter portion 40 and the large inner diameter portion 42. The cap member 44 constitutes a flange surrounding portion that surrounds almost the entire surface of the flange portion 32. In relation to the cap member 44, the shoulder 46 is provided with an annular recess, and an O-ring 48 is disposed in the annular recess. The O-ring 48 can be formed of, for example, synthetic rubber and seals between the cap member 44 and the sleeve member main body 36. The cap member 44 is fixed to the sleeve member main body 36 by means such as caulking.

  A closing member 50 is attached to one end portion (lower end portion in FIG. 1) of the sleeve member 26 so as to face one end portion of the shaft portion 28 of the shaft member 24 via a gap. The closing member 50 is composed of a circular plate-like member, and is fixed to an annular recess formed on one end surface (lower end surface) of the sleeve member main body 36 by means such as caulking. By providing the closing member 50 in this way, the small inner diameter portion 38 is closed at one end of the sleeve member 26, and the sleeve member 26 defines an accommodation space in which the one end is closed. As shown in FIG. 1, the defined accommodation space surrounds one end portion of the shaft portion 28 of the shaft member 24, and this accommodation space communicates with the gap of the sleeve fitting portion. In the motor having such a configuration, the space between the sleeve member 26 and the shaft member 24 (this space is filled with the lubricating fluid) is opened to the outside at the other end (the large inner diameter portion 42 side) of the sleeve member 26. Therefore, it is only necessary to consider the leakage of the lubricating fluid from the other end side of the sleeve member 26.

  In the present embodiment, the thrust dynamic pressure bearing means and the radial dynamic pressure bearing means are arranged as follows. The radial dynamic pressure bearing means 52 and 54 are disposed at a distance in the axial direction between the shaft portion 28 of the shaft member 24 and the sleeve fitting portion of the sleeve member 26, and support the radial force acting on the shaft member 24. To do. The portion of the shaft portion 28 of the shaft member 24 between the pair of radial dynamic pressure bearing means 52 and 54 has a slightly smaller diameter than the other portions. The dynamic pressure grooves of the radial dynamic pressure bearing means 52 and 54 may be in the form of a herringbone, a spiral, or the like, and are formed on the inner peripheral surface of the small inner diameter portion 38 of the sleeve member 26 as indicated by a broken line in FIG. . Instead of providing the radial dynamic pressure groove on the inner peripheral surface of the sleeve member 26, for example, the radial dynamic pressure groove may be provided on the outer peripheral surface of the shaft portion 28 of the shaft member 24, or the inner peripheral surface of the sleeve member 26 and the shaft member 24. You may provide in both the outer peripheral surfaces of the axial part 28 of this. The thrust dynamic pressure bearing means 56 is provided on the inner surface of the flange portion 32 of the shaft member 24 (one surface on the lower side in FIG. 1), and supports the thrust force acting on the shaft member 24. The dynamic pressure groove of the thrust dynamic pressure bearing means 56 may be in the shape of a herringbone, a spiral or the like, and is formed on the inner surface of the flange portion 32 as indicated by a broken line in FIG. Instead of providing the thrust dynamic pressure groove on the inner surface of the flange portion 32, the opposing surface of the sleeve member 26 facing this one surface of the flange portion 32, that is, the small inner diameter portion 38 and the medium inner diameter portion of the sleeve member 26. 40 may be provided on the surface of the shoulder portion 58 (which constitutes the first opposing surface) between the flange portion 32 and the surface of the shoulder portion 58 of the sleeve member 32. You may do it.

  In the embodiment, a taper seal is formed on the inner surface of the cap member 44 (which constitutes the second opposing surface of the sleeve member 26) that faces the outer surface of the flange portion 32 of the shaft member 24 (the other surface on the upper side in FIG. 1). A taper 60 constituting the structure is provided. The taper 60 has a gap between the taper 60 and the flange portion 32 that is radially outward, and defines an annular taper space facing the other surface of the flange portion 32. The taper 60 applies a force directed outward in the radial direction to the lubricating fluid by surface tension. In the taper 60, the gap between the cap member 44 and the flange portion 32 is reduced outward in the radial direction. Therefore, when the shaft member 24 and the sleeve member 26 are rotated relative to each other by the rotation of the motor, the lubricating fluid of the taper 60 is obtained. In addition, the outward force in the radial direction is also exerted by the centrifugal force generated by the rotation, and the movement of the lubricating fluid in the leakage direction (inward in the radial direction) is reliably prevented. The radial outward force due to the centrifugal force also acts when the lubricating fluid radiates inward in the radial direction (so-called migration), the mist of the lubricating fluid, the scattering due to the impact, etc., and the lubricating fluid (or The fine particles) are collected radially inward by this centrifugal force. The taper 60 can be provided on the outer end surface of the flange portion 32 of the shaft member 24 instead of or together with the inner surface of the cap member 44, but can be easily formed by being provided on the cap member 44. In the present embodiment, a relatively wide range of at least most of the inner surface of the cap member 44 is provided without providing a thrust dynamic pressure groove in the other surface of the flange portion 32 and the region of the inner surface of the cap member 44 facing the other surface. Since the taper 60 is provided, a relatively large tapered space can be formed, and a sufficient fluid reservoir for the lubricating fluid can be obtained. The taper 60 has a sealing interface for the lubricating fluid, and the taper 60 also has a sealing function. As described above, since the taper 60 is provided by utilizing at least the most region of the flange portion 32 (or the inner surface of the cap member 44 facing this region), even when the temperature rises and the lubricating fluid expands, The taper 60 can absorb thermal expansion, and even if the lubricating fluid evaporates due to long-term use, the lubricating fluid stored in the taper 60 can be used as a replenishing fluid. In the illustrated embodiment, in order to ensure a sufficient tapered space, the open end of the taper 60 is located at a position close to the shaft portion 28 of the shaft member 24, and the peripheral edge of the flange portion 32 from the radially inner position. Is formed in a straight line when viewed in cross-section up to a position facing the. On the radially inner side of the taper 60, an annular groove 61 is formed on the other surface of the flange portion 32 of the shaft member 24, which is located near the base portion of the flange portion 32 of the shaft member 24 to the shaft portion 28. The groove 61 is coated with an oil repellent 63 (FIG. 2) that suppresses the flow of the lubricating fluid. The oil repellent 63 repels the lubricating fluid and prevents the inward flow and bleeding in the radial direction.

  Such a configuration can be advantageously applied to a relatively small motor, for example, a spindle motor for a hard disk that rotates a magnetic disk having a diameter of 2.5 inches or less, and the dimensions of various components are set as follows. can do. Referring to FIG. 2, for example, the outer diameter D1 of the shaft portion 28 of the shaft member 24 is set to 3.0 to 3.5 mm, the outer diameter D2 of the flange portion 32 is set to 6.0 to 6.5 mm, and the flange portion 32 is The thickness T is set to 1.0 to 1.5 mm, the interval W between the open side end P of the taper 60 and the shaft portion 28 is set to 0.4 to 0.5 mm, and the closed side end Q of the taper 60 is set to the peripheral edge of the flange portion 32. The taper angle α from the closing side Q of the taper 60 to the open end P is set to 20 to 30 degrees.

  In the present embodiment, as shown in FIG. 1, the lubricating fluid 62 of the hydrodynamic bearing device is such that the seal interface is located at the taper 60, and the shaft member 24 and the sleeve member 26 below the seal interface. It is filled substantially over the entire gap. That is, the lubricating fluid 62 substantially continues from one end surface of the shaft portion 28 of the shaft member 24 (the surface facing the closing member 50) to the taper 60 through the radial dynamic pressure bearing means 52 and 54 and the thrust dynamic pressure bearing means 56. Filled. Therefore, as can be easily understood, the taper 60 for preventing leakage of the lubricating fluid 62 need only be provided at one location, and the structure of the hydrodynamic bearing device and the motor using the same can be simplified. And the possibility of leakage of the lubricating fluid 62 is reduced.

  Since the lubricating fluid 62 is also filled into one end surface of the shaft portion 28 of the shaft member 24, auxiliary thrust dynamic pressure bearing means 64 may be provided on one end surface of the shaft portion 28. The auxiliary thrust dynamic pressure bearing means 64 is provided to adjust the thrust force of the thrust dynamic pressure bearing means 56 provided on the flange portion 32 of the shaft member 24. The dynamic pressure groove of the thrust dynamic pressure bearing means 64 may be in the shape of a herringbone, a spiral or the like, and is formed on one end surface of the shaft portion 28 as indicated by a broken line in FIG. The auxiliary thrust dynamic pressure groove may be provided on the inner surface of the closing member 50 instead of being provided on the one end surface of the shaft portion 28, and may be provided on both the one end surface of the shaft portion 28 and the closing member 50. It may be.

  As the auxiliary thrust dynamic pressure bearing means 64, a pump-in type dynamic pressure groove structure is employed when the thrust support force by the thrust dynamic pressure bearing means 56 is increased, that is, when the force to lift the shaft member 28 is increased. In this case, the lubricating fluid 62 flows inward in the auxiliary thrust dynamic pressure bearing means portion 64, and thereby a levitation force acts on the shaft member 24, and thus the rotor 10.

  The present embodiment is configured as follows in order to discharge the air mixed in the lubricating fluid 62 to the outside. That is, the shaft member 24 is provided with a pressure adjusting channel 66 of the lubricating fluid 62 having an outlet formed on the outer peripheral surface of the flange portion 32 and an inlet formed on one end surface of the shaft portion 28. Specifically, the injection hole 34 formed in the shaft portion 28 is used as a vertical hole of the channel 66, and a communication hole 67 communicating with the injection hole 34 from the outer peripheral surface of the flange portion 32 is formed. The upper part of the injection hole 34 from the communication hole 67 is closed by an elastic plug 70 described later. Here, part or all of the dynamic pressure grooves in the radial dynamic pressure bearing means 52, 54, the thrust dynamic pressure bearing means 58 and the auxiliary thrust dynamic pressure bearing means 64 are such that the lubricating fluid 62 flows from the outlet of the channel 66 to the flange portion 32. The groove shape is devised so as to pass through the circumferential surface and the entire surface of the shaft portion 28, move downward on the outer periphery of the shaft portion 28, and flow into the channel 66 from the end surface, and lubricate through the circulation path including the channel 66. The fluid 62 is circulated. By circulating the lubricating fluid 62 in this way, the fluid pressure generated by the thrust dynamic pressure groove 56 and the radial dynamic pressure grooves 52 and 54 is also adjusted.

  Further, the gap L1 between the outer peripheral surface of the flange portion 32 and the inner peripheral surface of the inner diameter portion 40 of the sleeve member main body 36 opposed to the flange portion 32 causes the lubricating fluid 62 to flow by capillary action as shown in an enlarged view in FIG. The interval for holding is set to a dimension such as L1 = 50 μm or slightly smaller than that. Therefore, when the bubbles mixed in the lubricating fluid 62 expand due to the temperature rise, the expanded bubbles are guided to the outer peripheral surface of the flange portion 32 by the circulation of the lubricating fluid 62, where the bubbles are separated into air and the lubricating fluid 62, and lubricated. The fluid 62 is circulated again toward the thrust dynamic pressure bearing means 58, and the air passes through between the shaft member 24 and the cap member 44 from the tapered portion 60 and is discharged to the outside.

  A filter 68 can be disposed in the channel 66 as required. The filter 68 is disposed in the injection hole 34 and can be formed of, for example, a porous material or a fiber material. The filter 68 captures impurities such as wear powder in the lubricating fluid 62, thereby improving the reliability of the hydrodynamic bearing device 11.

  As shown in detail in FIG. 2, an annular throttle protrusion 69 that protrudes outward in the radial direction is provided on the outer peripheral surface of one side (lower side) of the flange portion 32. A gap L2 between the outer peripheral surface of the throttle protrusion 69 and the inner peripheral surface of the medium inner diameter portion 40 is set to 20 μm, for example. The throttle protrusion 69 cushions the applied impact by moving in the lubricating fluid 62 against the axial impact of the shaft member 24. The throttle protrusion 69 is located below the communication hole 67 in the circulation path of the lubricating fluid 62, and further, the gap L1 is greatly throttled, so that the bubbles are effectively separated from the lubricating fluid 62.

  In the present embodiment, the stator 18 is mounted on the outer peripheral surface of the sleeve member 26 of the hydrodynamic bearing device 11 and supported by the base plate 2 via the sleeve member 26. Instead, for example, the base plate 2 An annular support wall may be provided, and the stator 18 may be attached to the annular support wall. In relation to the stator 18, the magnetic center between the stator 18 and the rotor magnet 16 attached to the rotor 10 is arranged slightly shifted in the axial direction of the shaft member 24. In other words, the magnetic center of the magnet 16 is arranged somewhat shifted from the magnetic center of the stator 18 in the vertical direction (vertical direction in FIG. 1). Therefore, a biasing force in a direction close to the base plate 2 (a biasing force in a direction in which one end surface of the shaft member 24 is close to the closing member 50) acts on the rotor 10 by the magnetic attraction action of the magnet 16 with respect to the stator 18. . During rotation of the motor, the thrust force generated by the axial dynamic force bearing means 58 on the shaft member 24 to lift upward in FIG. 1 (when the auxiliary thrust dynamic pressure bearing means 64 is provided) 1), the thrust force is balanced with the magnetic biasing force, ie, the magnetic back pressure, that the magnet 16 and the stator 18 try to hold down in FIG. 1, and the rotor 10 is stable in the vertical direction. Rotate. This magnetic biasing force also prevents the rotor 10 from coming off the sleeve member 26.

  The lubricating fluid 62 can be injected into the dynamic pressure fluid bearing device 11 in a relatively simple and reliable manner, for example, by the following operation. 3 (a) to 3 (d), in order to inject the lubricating fluid 62, first, as shown in FIG. 3 (a), a filter 68 is attached to the injection hole 34, and then the shaft member 24 is attached. The elastic plug 70 is temporarily attached to the formed injection hole 34. The plug 70 can be formed of, for example, synthetic rubber, natural rubber, or the like, and preferably has a shape corresponding to the shape of the tapered portion 34a of the injection hole 34. One end portion of the tapered portion 72 of the elastic plug 70 is provided with a small diameter portion 74 corresponding to the small inner diameter portion of the injection hole 34, and a large diameter portion 76 corresponding to the large inner diameter portion of the injection hole 34 at the other end portion. Is provided. As shown in FIG. 3A, the plug body 70 is temporarily mounted so that the tapered portion 72 is located on the tapered portion 34 a of the injection hole 34 from the rotor 10 side. Thus, when temporarily mounted, the small diameter portion 74 is positioned at the small inner diameter portion of the injection hole 34 and the large diameter portion 76 is positioned at the large inner diameter portion of the injection hole 34. In this temporary mounting state, the lubricating fluid 62 to be injected is plugged. It does not leak from the body 70.

  Next, as shown in FIG. 3 (b), the hollow needle 78 is inserted through the plug 70 that has been temporarily mounted, and the tip thereof protrudes into the small inner diameter portion of the injection hole 34. Thereafter, the lubricating fluid 62 is passed through the hollow needle 78 to the back side of the plug body 70, that is, the small inner diameter portion of the injection hole 34 and the dynamic pressure space of the dynamic pressure fluid bearing device 11 communicating therewith, that is, the shaft member 24 and the sleeve member. Lubricating fluid 62 is injected into the gap defined between.

  Next, as shown in FIG. 3C, after the hollow needle 78 is pulled out from the plug body 70, the plug body 70 is pushed in with a rod-shaped pressing tool 82, and as shown in FIG. Is pressed into the small inner diameter portion of the injection hole 34. When the hollow needle 78 is pulled out, a needle penetration mark 80 is generated in the plug 70, and evaporation, leakage, etc. of the lubricating fluid 62 may occur from the needle penetration mark 80 due to long-term use of the dynamic pressure fluid bearing device 11. There is. Therefore, after the hollow needle 78 is pulled out, it is press-fitted into the small inner diameter portion of the injection hole 34. By press-fitting in this way, the large-diameter portion 76 of the plug body 70 is particularly elastically deformed, and the large-diameter portion 76 securely and reliably closes the injection hole 34, and the needle penetration mark 80 in the large-diameter portion 76. Is reliably closed, and evaporation, leakage, etc. of the lubricating fluid 62 through the plug 70 are reliably prevented. It should be noted that the elastic plug body 70 is somewhat elastically deformed when temporarily attached to the injection hole 34, and is preferably greatly elastically deformed when further press-fitted from the temporarily attached state, and may have an appropriate shape such as this.

  When the plug 70 is press-fitted into the small inner diameter portion of the injection hole 34, the lubricating fluid 62 existing inside thereof is fed into the dynamic pressure space of the radial dynamic pressure bearing means 52, 54 and the thrust dynamic pressure bearing means 56, As shown in FIG. 3D, the lubricating fluid 62 is filled up to a predetermined level from the small inner diameter portion of the injection hole 34 through one end surface of the shaft portion 28 of the shaft member 24, the outer periphery of the shaft portion 28, and the inner surface of the flange portion 32. In this way, when filled to a predetermined level, the sealing interface of the lubricating fluid 62 is located at the taper 60 of the cap member 44. Such an injection operation of the lubricating fluid 62 is preferably performed in a vacuum chamber, and the space into which the lubricating fluid 62 is injected is located on the upper side as shown in FIGS. 3 (a) to 3 (d). In the embodiment, it is desirable to hold the rotor 10 so as to be positioned on the lower side.

  In the above-described embodiment, the present invention is applied to the shaft rotation type motor. However, the present invention can be similarly applied to the shaft fixed type motor shown in FIG. In FIG. 4 showing a second embodiment of the motor, the illustrated motor includes a base plate 102 and a rotor 104 that is rotatable relative to the base plate 102, and a hydrodynamic fluid is interposed between the base plate 102 and the rotor 104. A bearing device 106 is interposed. The hydrodynamic fluid bearing device 106 in the present embodiment has substantially the same configuration as the hydrodynamic fluid bearing device 11 shown in FIG. 1, and therefore only the differences will be described later.

  In this embodiment, the dynamic pressure fluid bearing device 106 is used upside down from the application example in the embodiment of FIG. That is, one end of the sleeve member 108 of the hydrodynamic fluid bearing device 106 (the end where the closing member 110 is provided) is coupled to the rotor 104. Further, the protruding end portion of the shaft member 112 (the end portion protruding in the axial direction from the flange portion 116 of the shaft portion 114) is coupled to the base plate 102. The base plate 102 is provided with an annular support wall 118 outside the sleeve member 106, and a stator 120 is attached to the annular support wall 118.

  In this motor, since the shaft member 112 is fixed to the base plate 102, the sleeve 108 is driven to rotate integrally with the rotor 104 in a predetermined direction with respect to the shaft member 112, and thus the base plate 102.

  As can be understood from the above description, the hydrodynamic fluid bearing device can be used as a common component, and even in its use, it may be used so that the closing member that closes one end of the sleeve member is located on the upper side. On the contrary, it can also be used so that the closing member is positioned on the lower side, and the same effect is achieved as the dynamic pressure fluid bearing device.

  Referring to FIG. 5 together with FIG. 4, in this second embodiment, the radial dynamic pressure bearing means 122, 124 are provided at the shaft portion 114 of the shaft member 112, that is, the sleeve fitting portion with the sleeve member 108. Dynamic pressure grooves 126 and 128 of the radial dynamic pressure bearing means 122 and 124 are formed on the outer peripheral surface of the shaft portion 114. Further, the thrust dynamic pressure bearing means 130 is provided on one surface of the flange portion 116 (the upper surface in FIGS. 4 and 5), and the dynamic pressure groove 132 of the thrust dynamic pressure bearing means 130 is formed on this one surface. The groove shapes of the radial dynamic pressure grooves 126 and 128 and the thrust dynamic pressure groove 132 are not clearly shown in FIG. 1, but are similarly formed in the first embodiment.

  In the second embodiment, the flange portion 116 of the shaft member 112, the outlet is the outer peripheral surface of the flange portion 116, and the inlet is the side where the taper 136 is provided at the base portion of the flange portion 116 with the shaft portion 114. A pressure adjusting channel 138 formed on one surface (inner surface) on the opposite side is provided. In this case, the dynamic pressure groove of the thrust dynamic pressure bearing means 130 formed on one surface of the flange portion 116 is such that the lubricating fluid 124 flows into the channel 138 from the outer periphery of the flange portion 116 through the thrust dynamic pressure bearing means 130. The shape of the channel 138 is devised, and the channel 138 forms a circulation path by the gap between the outer periphery and one surface of the flange portion 116 and the inner surface of the sleeve member 108 opposed to the outer periphery. Therefore, although air bubbles are likely to accumulate in the connecting portion between the shaft portion 114 and the flange portion 116, the inlet of the channel 126 is opened at the root portion of the flange portion 116 to the shaft portion 114, so that the lubricating fluid 124 By circulating through the circulation path, the bubbles are smoothly discharged to the outside in the same manner as described in the first embodiment. As shown in FIG. 5, the inlet of the channel 126 is preferably provided radially inward from the region where the dynamic pressure groove 132 of the thrust dynamic pressure bearing means 130 is formed, and the channel 126 is spaced apart in the circumferential direction. Two or more may be provided. In this second embodiment, the lubricating fluid circulation structure in the first embodiment may be adopted, and on the contrary, the lubricating fluid circulation structure in the second embodiment is changed to the first embodiment. It may be used.

  In this embodiment, when the auxiliary thrust dynamic pressure bearing means is provided on the end surface (upper surface) of the shaft portion 114, the pump-in type or the pump-out type is considered in consideration of only the balance of the thrust force regardless of the circulation of the lubricating fluid 124. Can be adopted. In the case of the pump-in type, a levitation force can be applied to the rotor 104 as described in the first embodiment. On the other hand, when reducing the thrust supporting force by the thrust dynamic pressure bearing means 130, that is, when reducing the force to lift the shaft member 112, a pump-out type dynamic pressure groove is employed. In this case, the lubricating fluid 123 flows out to the outside in the auxiliary thrust dynamic pressure bearing means, whereby a suction force is applied to the shaft member 112, and thus the rotor 104, toward the end surface of the shaft portion 114.

  In each of the above-described embodiments, the case where the hydrodynamic bearing is used for the motor has been described. However, it is also possible to use the bearing as a bearing device that supports the rotation shaft in a rotating manner. In such a case, since there is no rotor magnet and stator for causing the shaft member to apply a magnetic force in a predetermined direction that balances the thrust force generated by the thrust dynamic pressure bearing means, a force that balances the thrust force on the shaft member. It is necessary to provide a separate means for acting.

  In FIG. 6 showing a single use example as a dynamic pressure fluid bearing device, the illustrated dynamic pressure fluid bearing device includes a sleeve member 202 and a shaft member 204 that is rotatable relative to the sleeve member 202. . A closing member 206 is attached to one end of the sleeve member 202. In this example, the shaft member 204 is made of a magnetic material, and a magnet piece 208 is used as means for applying a biasing force to the shaft member 204. The closing member 206 is made of a nonmagnetic material, and a disk-shaped magnet piece 208 is fixed to the outer surface of the closing member 206. A magnetic field from the magnet piece 208 acts on the shaft member 204 through the closing member 206, and a magnetic force in a direction close to the closing member 206 acts on the shaft member 204 by the magnetic action of the magnet piece 208. In this example, radial dynamic pressure bearing means 214 and 216 are provided on the shaft portion 210 of the shaft member 204, and thrust dynamic pressure bearing means 218 is provided on one surface (the lower surface in FIG. 6) of the flange portion 212. The magnetic force generated by the magnet piece 218 is set so as to balance the thrust force generated by the dynamic pressure groove of the thrust dynamic pressure bearing means 218.

  In this example, the shaft member 204 is provided with a pressure adjusting channel 220. The channel 220 has a vertical hole 200 a that opens in the end surface of the shaft portion 210 of the shaft member 204 and extends in the axial direction, and a communication hole 200 b that extends radially outward from the vertical hole 200 a and opens to the outer periphery of the flange portion 212. It is composed of The lubricating fluid 222 is guided from the end face of the shaft portion 210 through the channel 220 to the outer periphery of the flange portion 212, and further through the gap defined between the flange portion 212 and the shaft portion 210 of the sleeve member 202. It is circulated through a circulation path that reaches the end face of 210. Since the above-described circulation of the lubricating fluid is substantially the same as that of the first embodiment, the same effect as described above is achieved, and the bubbles in the lubricating fluid 222 are discharged to the outside by this circulation. The other structure of the hydrodynamic bearing device is substantially the same as that employed in the first embodiment.

  In such a support structure by the hydrodynamic bearing device, the shaft member 204 is not shown, but for example, a driving force transmission mechanism such as a pulley and a belt (not shown) is output from a driving source such as an electric motor. Drive-connected to the shaft and driven to rotate in a predetermined direction by the action of a drive source.

  In the motor of each embodiment, since the taper is formed over a relatively wide range of one or both of the other surface of the flange portion of the shaft member and the second facing surface of the sleeve member facing this, it is defined by the taper. The tapered space to be formed can be made relatively large. This taper has a reservoir function for holding the lubricating fluid in addition to a sealing function by surface tension, and can secure a sufficient space for the lubricating fluid seal interface and the lubricating fluid reservoir. Therefore, even if the temperature rises and the lubricating fluid expands, the taper can absorb the thermal expansion, and even if the lubricating fluid evaporates due to long-term use, the lubricating fluid stored in this taper is replenished. It can be used as a fluid. In addition, since the taper is narrower in the radially outward direction, the lubricating fluid existing in the taper is subjected to a radially outward force due to surface tension, and the shaft member and the sleeve member. The centrifugal force generated when the two parts rotate relative to each other also exerts a radially outward force, and the movement of the lubricating fluid in the leakage direction (inward in the radial direction) is reliably prevented. The outward force in the radial direction due to this centrifugal force is effective even when lubrication fluid bleeds inward in the radial direction (so-called lubrication fluid migration), mist of the lubrication fluid, and scattering due to impact. The lubricating fluid (or fine particles thereof) that moves inward in the radial direction is recovered radially inward by centrifugal force, and leakage due to bleeding, mist, scattering, etc. of the lubricating fluid can be prevented. Further, since the stator and the rotor magnet are in a relative positional relationship such that a magnetic back pressure in a predetermined direction acts on the shaft member, the magnetic back pressure by the magnetic biasing means by the stator and the rotor magnet is generated by the thrust dynamic pressure groove. The thrust force acting on the shaft member is balanced without providing the thrust dynamic pressure bearing means on the other surface side of the flange portion, and the rotor including the rotor magnet can be rotated stably. .

  The sleeve member is provided with a closing member facing the shaft portion of the shaft member, and the sleeve member defines an accommodation space that surrounds the end portion of the shaft member together with the closure member, and the accommodation space is a sleeve fitting portion. Therefore, the seal for the lubricating fluid may be provided only on the other surface of the flange portion of the shaft member, and can be reliably sealed with a relatively simple structure.

  In addition, since the shaft member is provided with a channel that connects the peripheral surface of the flange portion and the end surface of the shaft portion, the lubricating fluid filled between the shaft member and the sleeve member passes through this channel and is thrust. Circulating through the dynamic pressure bearing means and the radial dynamic pressure bearing means, the fluid pressure generated by the thrust dynamic pressure bearing means and the radial dynamic pressure bearing means is adjusted. Even if bubbles are mixed in the lubricating fluid, the bubbles mixed by the circulation of the lubricating fluid are guided to the peripheral surface of the flange portion, and are separated into the lubricating fluid and air at the outer periphery of the flange portion. It is discharged outside.

  Further, since the pressure adjusting channel includes a vertical hole extending in the longitudinal direction and a communication hole communicating the vertical hole and the outer periphery of the flange portion, the channel can be formed relatively easily.

  In addition, since the filter is disposed in the vertical hole, impurities mixed in the lubricating fluid can be captured.

  In addition, air bubbles mixed in the lubricating fluid are likely to collect at the connection between the shaft portion of the shaft member and the flange portion, but the root portion of the flange portion to the shaft portion and the outer periphery of the flange portion are connected by a channel, so The air bubbles are guided to the outer periphery of the flange portion through the channel, separated into the lubricating fluid and air at the outer periphery of the flange portion, and the separated air is discharged to the outside.

  In addition, since the gap between the peripheral surface of the flange portion and the inner peripheral surface of the sleeve member facing the flange portion is set so as to hold the lubricating fluid by capillarity, bubbles introduced to the outer periphery of the flange portion through the channel Is prevented from entering the interior and no leakage of the lubricating fluid occurs.

  Further, since the side of the flange portion on the side where the thrust dynamic pressure bearing means is provided is provided with a buffering throttle projection protruding radially outward, the axis of the shaft member and the sleeve member The relative movement in direction is buffered by the movement of the throttling protrusion in the lubricating fluid. Further, the flow of bubbles mixed in the lubricating fluid to the thrust dynamic pressure bearing means is also prevented.

  Further, since the cover portion covering the thrust portion of the sleeve member is provided with a taper, the taper can be formed relatively easily.

  In addition, since the lubricant is applied to the annular groove provided in the flange portion, the leakage of the lubricating fluid can be prevented more reliably.

  Further, a taper is formed over a relatively wide range of one or both of the other surface of the flange portion of the shaft member and the second facing surface of the sleeve member facing the flange portion, and the taper is spaced radially outward. Since it is narrow, the same action as described above is achieved. In addition, since a force in the opposite direction to the thrust support force generated by the thrust dynamic pressure groove acts on the shaft member, the thrust support force and the force in the opposite direction are balanced, and the thrust member moves to the other surface side of the flange portion. The shaft member can be stably rotated without providing the pressure bearing means.

  The sleeve member is provided with a closing member facing the shaft portion of the shaft member, and the sleeve member defines an accommodation space that surrounds the end portion of the shaft member together with the closure member, and the accommodation space is a sleeve fitting portion. It is continuous with the gap. The shaft member is provided with a channel that communicates the peripheral surface of the flange portion and the end surface of the shaft portion. Therefore, as described above, it is easy to seal the lubricating fluid, and the lubricating fluid is circulated through the channel through the thrust dynamic pressure bearing means and the radial dynamic pressure bearing means, and the thrust dynamic pressure bearing means and the radial dynamic pressure are circulated. The fluid pressure generated in the bearing means is adjusted, and the bubbles in the lubricating fluid are separated from the lubricating fluid and discharged to the outside.

  Further, since the elastic plug is attached to the lubricating fluid injection hole, leakage of the injected lubricating fluid is prevented.

  In addition, since the injection hole used for injecting the lubricating fluid constitutes a part of the lubricating path for lubricating the lubricating fluid, the injection hole after the injection is not wasted at all, and the thrust dynamic pressure bearing means and the radial dynamic pressure It also has a function of adjusting the fluid pressure generated by the bearing means, and the configuration for the lubricating path and pressure adjusting function of the lubricating fluid is simplified.

  In addition, since the shaft member is made of a magnetic material and a magnet piece for magnetically attracting the shaft member is provided, the balance with the thrust force generated by the thrust dynamic pressure bearing means can be maintained with a relatively simple configuration. Can do.

  Further, the outer surface of the flange portion is provided with a taper seal structure in cooperation with the facing surface of the sleeve member facing the flange portion, and this taper seal structure portion is also used as a lubricating fluid reservoir. It is possible to provide a lubricating fluid sealing function and a reservoir function with a simple structure. In addition, since the means for causing the shaft member to exert a force that balances the thrust support force of the thrust dynamic pressure bearing means is provided, the shaft member can be supported stably.

  Further, the outer surface of the flange portion is provided with a taper seal structure in cooperation with the facing surface of the sleeve member facing the flange portion, and this taper seal structure portion is also used as a lubricating fluid reservoir. It is possible to provide a lubricating fluid sealing function and a reservoir function with a simple structure. Further, since the stator and the rotor magnet are disposed in a relative positional relationship so that a magnetic force that balances the thrust support force of the thrust dynamic pressure bearing means is applied to the shaft member, the rotor including the rotor magnet is stably supported. can do.

  In addition, since the circulation path for circulating the lubricating fluid is provided, the fluid pressure generated by the thrust dynamic pressure fluid bearing means and the radial dynamic pressure bearing means is adjusted by the circulation action of the lubricating fluid, and the shaft member rotates stably. To do.

  In addition, since the filter is disposed in the circulation path, impurities mixed therein are captured by the circulation of the lubricating fluid.

  Further, since the taper is provided over a relatively wide range of the surface of the sleeve member facing the flange portion of the shaft member, this taper can provide a taper seal structure having a sufficient taper space and lubrication. A sufficient reservoir of fluid can be provided.

According to the embodiment, a shaft member having a shaft portion and a disk-shaped flange portion that protrudes radially outward from the shaft portion and rotates integrally with the shaft portion, and a predetermined interval between the shaft member and the shaft member. A sleeve member that fits the sleeve portion, surrounds the flange portion, and is rotatable relative to the shaft member; and a lubricating fluid filled in a gap between the sleeve member and the shaft member. In a motor equipped with a hydrodynamic bearing device,
A radial dynamic pressure groove is provided in one or both of the shaft portion of the shaft member and the mutually facing surfaces of the sleeve member, and one or both of the one surface of the flange portion of the shaft member and the first facing surface of the sleeve member facing this are provided. A thrust dynamic pressure groove is provided,
One or both of the other surface of the flange portion of the shaft member and the second facing surface of the sleeve member facing the shaft member is directed radially outward in a relatively wide range from a position close to the shaft portion to the periphery of the flange portion. A taper that narrows the spacing is formed,
The gap between the sleeve fitting part of the sleeve member and the shaft member of the part surrounding the flange part is continuous, and the lubricating fluid is continuously filled from the gap of the sleeve fitting part to the gap of the flange peripheral surface,
A stator is integrally provided on one of the shaft member and the sleeve member, and a rotor magnet is integrally provided on the other, and the stator and the rotor magnet are generated by a thrust dynamic pressure groove. A motor is provided that is in a relative positional relationship such that a magnetic back pressure in a direction opposite to the thrust support force that balances the thrust support force is applied to the shaft member.

Further, a shaft member having a disc-shaped flange portion that protrudes radially outward from the shaft portion and rotates integrally with the shaft portion, and a predetermined interval between the shaft member and the shaft portion are fitted into the sleeve. A hydrodynamic bearing device comprising: a sleeve member that surrounds the flange portion and is rotatable relative to the shaft member; and a lubricating fluid filled in a gap between the sleeve member and the shaft member In
Radial dynamic pressure grooves are provided on one or both of the shaft portion of the shaft member and the mutually opposing surfaces of the sleeve member,
A thrust dynamic pressure groove is provided on one or both of one surface of the flange portion of the shaft member and the first facing surface of the sleeve member facing the flange portion,
One or both of the other surface of the flange portion of the shaft member and the second facing surface of the sleeve member facing the shaft member is directed radially outward in a relatively wide range from a position close to the shaft portion to the periphery of the flange portion. A taper that narrows the spacing is formed,
The gap between the sleeve fitting part of the sleeve member and the shaft member of the part surrounding the flange part is continuous, and the lubricating fluid is continuously filled from the gap of the sleeve fitting part to the gap of the flange peripheral surface,
A dynamic pressure fluid bearing device is provided in which a force in a direction opposite to a thrust support force that balances a thrust support force generated by a thrust dynamic pressure groove is applied to the shaft member.

Further, the shaft portion and a shaft member having a disk-like flange portion that protrudes radially from the shaft portion and rotates integrally with the shaft portion, and the shaft portion are sleeve-fitted with a predetermined interval between the shaft member. And a sleeve member that surrounds the flange portion and is relatively rotatable with respect to the shaft member, and is filled to a predetermined level of a continuous gap from the sleeve fitting portion between the sleeve member and the shaft member to the flange surrounding portion. A hydrodynamic bearing device comprising a lubricating fluid
A radial dynamic pressure bearing means is provided at the sleeve fitting portion, and a thrust dynamic pressure bearing means is provided at a portion between the inner surface side of the flange portion and the facing surface of the sleeve member facing the flange portion, and the outer surface of the flange portion is the sleeve member facing the sleeve In addition to forming a taper seal structure that seals the lubricating fluid by surface tension in cooperation with the opposite surface of
There is provided a hydrodynamic fluid bearing device comprising means for causing a shaft member to apply a force that balances the thrust support force of the thrust hydrodynamic bearing means on the inner surface side of the flange portion.

Further, the shaft portion and a shaft member having a disk-like flange portion that protrudes radially from the shaft portion and rotates integrally with the shaft portion, and the shaft portion are sleeve-fitted with a predetermined interval between the shaft member. And a sleeve member that surrounds the flange portion and is relatively rotatable with respect to the shaft member, and is filled to a predetermined level of a continuous gap from the sleeve fitting portion between the sleeve member and the shaft member to the flange surrounding portion. A lubricating fluid, a stator coupled to one of the shaft member and the sleeve member, and a rotor magnet coupled to rotate integrally with the other of the shaft member and the sleeve member,
A radial dynamic pressure bearing means is provided at the sleeve fitting portion, and a thrust dynamic pressure bearing means is provided at a portion between the inner surface side of the flange portion and the facing surface of the sleeve member facing the flange portion, and the outer surface of the flange portion is the sleeve member facing it. In addition to forming a taper seal structure that seals the lubricating fluid by surface tension in cooperation with the opposite surface of
There is provided a motor characterized in that the stator and the rotor magnet are arranged in a relative positional relationship so that a magnetic force that balances the thrust support force of the thrust dynamic pressure bearing means on the inner surface side of the flange portion is applied to the shaft member. The

It is principal part sectional drawing which shows 1st Embodiment of the motor provided with the hydrodynamic bearing according to this invention. It is a partial expanded sectional view of the dynamic pressure fluid bearing part in the motor of FIG. FIG. 2 is a simplified explanatory diagram illustrating a method for injecting a lubricating fluid in the motor of FIG. 1. It is principal part sectional drawing which shows 2nd Embodiment of the motor provided with the hydrodynamic bearing according to this invention. It is a fragmentary perspective view which expands and shows a part of shaft member in the motor of FIG. It is sectional drawing which shows the other example of the dynamic pressure fluid bearing according to this invention.

Explanation of symbols

2,102 Base plate 10, 104 Rotor 11, 106 Dynamic pressure fluid bearing device 16 Rotor magnet 18 Stator 24, 112, 204 Shaft member 26, 108, 202 Sleeve member 28, 114, 210 Shaft portion 32, 116, 212 Flange portion 34 Injection hole 44 Cap member 52, 54, 122, 124, 214, 216 Radial dynamic pressure bearing means 56, 130, 218 Thrust dynamic pressure bearing means 60, 122 Taper 62, 123, 222 Lubricating fluid 70 Elastic plug 208 Magnet piece

Claims (11)

A shaft member comprising: a shaft portion; and a disc-shaped flange portion that is configured integrally or separately with the shaft portion and protrudes radially outward from the shaft portion;
A small inner diameter portion opposed to the outer peripheral surface of the shaft portion and an inner diameter portion larger than the small inner diameter portion and opposed to the outer peripheral surface of the flange portion; one end side is closed and the other end side is opened; And a sleeve member rotatable relative to the shaft member;
A radial motion having a radial dynamic pressure groove formed in a gap between the outer peripheral surface of the shaft portion and the inner peripheral surface of the small inner diameter portion and inducing a dynamic pressure in the lubricating fluid held in the gap during the relative rotation. Pressure bearings,
A thrust dynamic pressure groove is formed in a gap between one surface of the flange portion and the first opposite surface of the sleeve member facing the flange portion, and induces a dynamic pressure in the lubricating fluid held in the gap during the relative rotation. A thrust dynamic pressure bearing having,
And a lubricating fluid that fills the gap between the radial dynamic pressure bearings and the gap between the thrust dynamic pressure bearings continuous with the radial dynamic pressure bearings without interruption and forms an interface only on the other end side. Dynamic pressure bearing device. On the other end side of the thrust dynamic pressure bearing, a taper seal is formed between the shaft member and the sleeve member so that the gap size decreases toward the thrust dynamic pressure bearing.
The fluid dynamic pressure bearing device according to claim 1, wherein the interface is located in the taper seal. The flange portion is surrounded by the sleeve member,
In the gap between the other surface of the flange portion and the second opposite surface of the sleeve member facing the other surface, a taper seal is formed in which the gap size decreases from the radially inner side to the outer side. And
The fluid dynamic pressure bearing device according to claim 1, wherein the interface is located in the gap where the taper seal is formed. The sleeve member includes a sleeve member main body having an inner diameter portion facing the outer peripheral surface of the small inner diameter portion and the flange portion, and a lid portion closing the inner diameter portion facing the outer peripheral surface of the flange portion,
The inner peripheral surface of the lid portion is located radially inward from the outer peripheral surface of the flange portion, thereby preventing any one of the shaft member and the sleeve member from slipping out of the other during the relative rotation. The fluid dynamic pressure bearing device according to any one of claims 1 to 3. The sleeve member includes a large inner diameter portion positioned on the other end side and larger in diameter than an inner diameter portion facing the outer peripheral surface of the flange portion,
The fluid dynamic pressure bearing device according to claim 4, wherein the lid portion is fixed to an inner peripheral surface of the large inner diameter portion.   The said shaft member or the said sleeve member is urged | biased by the magnetic force to the opposite direction to the thrust direction support force generate | occur | produced with the said thrust dynamic pressure bearing. Dynamic pressure fluid bearing device. A gap between one end portion of the shaft portion and the facing portion of the sleeve member facing the one end portion and a radially outer end portion of the thrust dynamic pressure bearing are used for pressure adjustment filled with the lubricating fluid. Through the hole,
The fluid dynamic pressure bearing device according to claim 1, wherein the lubricating fluid circulates through the pressure adjusting hole, the thrust dynamic pressure bearing, and the radial dynamic pressure bearing.   8. The fluid dynamic pressure bearing device according to claim 1, wherein an oil repellent agent is applied to a portion of the shaft member in the vicinity of the interface. A fixed portion including any one of the shaft member and the sleeve member, and a stator;
A rotor including the other of the shaft member and the sleeve member, and a rotor magnet facing the stator;
A motor comprising the fluid dynamic pressure bearing device according to claim 1. A fixed part;
A rotor facing the fixed portion;
A thrust dynamic pressure bearing having a thrust dynamic pressure groove formed in a gap between the fixed portion and the rotor and inducing a dynamic pressure in the lubricating fluid held in the gap during the relative rotation;
A taper seal that is formed in a gap between the fixed portion and the rotor, is connected to the thrust dynamic pressure bearing, and decreases in the gap dimension toward the thrust dynamic pressure bearing;
A lubricating fluid that is continuously filled in the thrust dynamic pressure bearing and the taper seal and forms an interface in the taper seal;
A throttle protrusion that is located at a portion that forms a gap from the thrust dynamic pressure bearing of the rotating portion or the rotor to the taper seal, and that projects from the portion to reduce the size of the gap. Fluid dynamic pressure bearing device. The fixing part is
A shaft member comprising: a shaft portion; and a disc-shaped flange portion that is configured integrally or separately with the shaft portion and protrudes radially outward from the shaft portion;
A small inner diameter portion opposed to the outer peripheral surface of the shaft portion and an inner diameter portion larger than the small inner diameter portion and opposed to the outer peripheral surface of the flange portion; one end side is closed and the other end side is opened; And a sleeve member rotatable relative to the shaft member, and the rotor comprises the other,
A radial dynamic pressure groove having a radial dynamic pressure groove that induces a dynamic pressure in the lubricating fluid held in the gap during the relative rotation is formed in the gap between the outer peripheral surface of the shaft portion and the inner peripheral surface of the small inner diameter portion. Bearings are formed,
The thrust dynamic pressure bearing is formed in a gap between one surface of the flange portion and a first facing surface of the sleeve member facing the flange portion,
The lubricating fluid is continuously filled without interruption into the gap constituting the radial dynamic pressure bearing and the gap constituting the thrust dynamic pressure bearing, and the interface is formed only within the taper seal. The dynamic pressure bearing device according to claim 10.

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