JP4743027B2 - Bearing unit and motor using the bearing unit - Google Patents

Description

  The present invention relates to a bearing unit that rotatably supports a rotating shaft or a rotating body that rotatably supports a shaft, and a motor using the bearing unit.

  Conventionally, as a bearing unit that rotatably supports a rotating shaft, one configured as shown in FIG. 14 is known.

  A bearing unit 100 shown in FIG. 14 supports a rotating shaft 101 in a rotatable manner, and includes a radial bearing 104 that supports the rotating shaft 101 in a circumferential direction, and a housing 105 that houses the radial bearing 104. .

  In this bearing unit 100, the radial bearing 104 constitutes a hydrodynamic bearing together with lubricating oil that is a viscous fluid filled in the housing 105, and the inner peripheral surface through which the rotating shaft 101 is inserted has a dynamic bearing. A dynamic pressure generating groove 111 for generating pressure is formed.

  As shown in FIG. 14, the housing 105 that houses the radial bearing 104 that supports the rotating shaft 101 has a shape that encloses and surrounds the radial bearing 104 that is formed in a cylindrical shape, and is integrally molded with synthetic resin. It is one member formed.

  The housing 105 includes a cylindrical housing main body 106, a bottom closing portion 107 constituting an end portion side portion formed integrally with the housing main body 106 so as to close one end side of the housing main body 106, and the housing main body 106. It comprises an upper closing part 108 formed integrally with a housing body 106 constituting the other end side. The housing 105 configured in this manner is formed by outsert-molding a synthetic resin material so as to surround the cylindrical radial bearing 104, so that the radial bearing 104 is disposed on the inner peripheral side of the housing body 106 and integrally formed. It is formed.

  A shaft insertion hole 109 through which the rotation shaft 101 rotatably supported by the radial bearing 104 housed in the housing 105 is provided is provided at the center of the upper closing portion 108. A thrust bearing 110 that integrally supports a bearing support portion 102 provided at one end portion in the thrust direction of the rotating shaft 101 supported by the radial bearing 104 is integrally formed at a central portion on the inner surface side of the bottom closing portion 107. ing.

  The thrust bearing 110 is formed as a pivot bearing that supports the bearing support portion 102 of the rotating shaft 101 that is formed in an arc shape or a tapered tip shape.

  By the way, the shaft insertion hole 109 has a gap 112 between the peripheral surface and the outer peripheral surface of the shaft body so that the lubricating oil 113 filled in the housing is sufficiently spaced to prevent leakage from the housing 105. It is formed.

  A tapered portion 114 is provided on the outer peripheral surface facing the inner peripheral surface of the shaft insertion hole 109 of the rotating shaft 101. The tapered portion 114 forms a pressure gradient in the gap 112 formed between the outer peripheral surface of the rotating shaft 101 and the inner peripheral surface of the shaft insertion hole 109, and the lubricating oil 113 filled in the housing 105 is supplied to the housing 105. Can be prevented from leaking out the lubricating oil 113 filled in the housing 105.

  In the bearing unit 100 configured as shown in FIG. 14, the rotation shaft 101 is exposed only at one end on the shaft insertion hole 109 side, and the housing member is seamlessly covered except for a slight gap in the shaft insertion hole 109. . Therefore, this bearing unit 100 can prevent the lubricating oil 113 from leaking out of the housing 105. In other words, the bearing unit 100 can surely prevent leakage as compared with a case where the housing is assembled by bonding two or more housing parts with a sealant such as an adhesive. In addition, since the communication portion with the outside is only the gap of the shaft insertion hole 109, it is possible to prevent scattering of the lubricating oil due to impact.

  However, in the bearing unit 100 described above, when the rotating shaft 101 and the housing 105 rotate relatively to generate dynamic pressure, the static pressure inside the bearing unit 100 is extremely reduced. As the pressure inside the housing 105 decreases, the air remaining in the housing 105 slightly or the residual air such as air dissolved in a viscous fluid such as lubricating oil is expanded. When the air inside the housing or the air dissolved in the viscous fluid is expanded, the viscous fluid may be pushed out to the exposed side of the shaft and leak. In the bearing unit 100, the lubricating oil leaks and cannot be held, so that good lubrication cannot be obtained.

  As described above, in the bearing unit 100 shown in FIG. 14, due to the generation of dynamic pressure due to the relative rotation of the rotating shaft and the housing, residual air inside the housing may expand and the lubricating oil may leak.

  In order to solve such a problem, for example, Japanese Patent Laid-Open No. 2005-69382 discloses one end side and the other end side in the thrust direction of the rotating shaft protruding from the radial bearing in addition to the configuration of the bearing unit as described above. A bearing unit having a communication path communicating therewith is described. By this communication path, pressure drop on the non-shaft opening side is prevented and residual air in the housing is discharged to the outside from the shaft insertion hole, thereby It is described to prevent the leakage of the above.

  However, even in such a bearing unit, there is a possibility that problems such as deterioration in rotational performance may occur due to a decrease in lubricating oil due to volatilization or deterioration over time.

JP 2005-69382 A

  An object of the present invention is to prevent the pressure in the housing from decreasing due to the relative rotation of the shaft and the housing, and to effectively discharge the residual air in the viscous fluid such as lubricating oil filled in the housing. The leakage of the viscous fluid inside the housing is pushed out of the bearing unit due to the expansion of the residual air due to the pressure drop in the housing, and the filling amount of the lubricating oil is easily increased. It is an object of the present invention to provide a bearing unit and a motor using the bearing unit.

A bearing unit according to the present invention includes a radial bearing that supports the shaft in the circumferential direction, a thrust bearing that supports one end of the shaft in the thrust direction, and the passage forming member provided outside the radial bearing and the thrust bearing. And a housing having a shaft insertion hole through which the shaft is inserted, a viscous fluid filled in the housing, the passage forming member, and the above A plurality of communication passages are formed between the radial bearings at equal intervals, and communicate with the one end side and the other end side in the thrust direction of the shaft protruding from the radial bearing. On the inner peripheral surface of the passage forming member , a plurality of holes are formed on the inner peripheral surface of the passage forming member at equal intervals to abut on the outer peripheral surface of the radial bearing and regulate positions in a plane orthogonal to the axial direction. As a viscous fluid holding portion for holding the viscous fluid between the bearing positioning projections, a plurality of axial slits are formed by the projections formed between the bearing positioning projections on the inner peripheral surface of the passage forming member. And at least one of the plurality of slit-like grooves serves as the communication path.

  The motor according to the present invention is a motor including a bearing unit that rotatably supports the rotor with respect to the stator, and the above-described bearing unit is used for the motor.

  The bearing unit according to the present invention and the motor using the bearing unit prevent a decrease in the pressure in the housing due to the relative rotation of the shaft and the housing and prevent the pressure in the viscous fluid such as lubricating oil filled in the housing. Residual air can be discharged satisfactorily, and leakage of the viscous fluid inside the housing is pushed out of the bearing unit due to expansion of the residual air due to the pressure drop inside the housing. The amount can be increased in a state where the amount can be easily maintained, and the lubricating oil can be reliably retained for a long period of time to maintain good rotation performance.

  Embodiments of a bearing unit to which the present invention is applied and a motor using the bearing unit will be described below with reference to the drawings.

  Here, a motor used for a heat dissipation device provided in an electronic apparatus such as a portable computer which is an information processing apparatus that performs arithmetic processing of various types of information will be described. A heat dissipation device is provided inside the portable computer or the like. The heat dissipation device includes a metal base, a motor 1 attached to the base, a fan 3 that is rotated by the motor 1, a fan case 4 that houses the fan 3, and a heat sink. The motor 1 that rotationally drives the fan 3 of the heat radiating device will be described in detail.

  As shown in FIG. 1, the motor 1 using the bearing unit 30 to which the present invention is applied includes a rotor 11 and a stator 12.

  The stator 12 is integrally provided on the upper surface plate 4 a side of the fan case 4 that houses the fan 3 that is rotated by the motor 1 together with the motor 1. The stator 12 includes a stator yoke 13, a bearing unit 30 to which the present invention is applied, a coil 14, and a core 15 around which the coil 14 is wound. The stator yoke 13 may be formed integrally with the upper surface portion 4a of the fan case 4, that is, may be formed by a part of the fan case 4, or may be formed separately. The stator yoke 13 is made of, for example, iron. The bearing unit 30 is fixed by press-fitting or bonding into a cylindrically formed holder 16 at the center of the stator yoke 13, and further by bonding together with press-fitting. The holder 16 into which the bearing unit 30 is press-fitted is formed in a cylindrical shape integrally with the stator yoke 13. Note that the fixing of the bearing unit 30 to the holder 16 is not limited to the above, and may be, for example, fixing by caulking, or fixing by engaging an elastic protrusion or the like.

  As shown in FIG. 1, a core 15 around which a coil 14 to which a drive current is supplied is attached is attached to the outer peripheral portion of the bearing unit 30 that is integrally fixed to the stator yoke 13.

  The rotor 11 that constitutes the motor 1 together with the stator 12 is attached to a rotary shaft 31 that is rotatably supported by the bearing unit 30, and rotates integrally with the rotary shaft 31. The rotor 11 includes a rotor yoke 17 and a fan 3 having a plurality of blades 19 that rotate integrally with the rotor yoke 17. The blade 19 of the fan 3 is formed integrally with the rotor yoke 17 by outsert molding on the outer peripheral surface of the rotor yoke 17.

  A ring-shaped rotor magnet 20 is provided on the inner peripheral surface of the cylindrical portion 17 a of the rotor yoke 17 so as to face the coil 14 of the stator 12. The magnet 20 is a plastic magnet in which S and N poles are alternately magnetized in the circumferential direction, and is fixed to the inner peripheral surface of the rotor yoke 17 with an adhesive. The magnet 20 may be a rubber magnet, a sintered magnet, or the like.

  The rotor yoke 17 is rotated by press-fitting a boss portion 21 provided with a through hole 21a provided in the central portion of the flat plate portion 17b into an attachment portion 32 provided on the distal end side of the rotating shaft 31 supported by the bearing unit 30. Attached to the shaft 31 so as to be rotatable.

  The motor 1 having the above-described configuration has a magnetic field generated in the coil 14 when a drive current is supplied to the coil 14 on the stator 12 side from a drive circuit unit provided outside the motor 1 according to a predetermined energization pattern. And the magnetic field from the rotor magnet 20 on the rotor 11 side cause the rotor 11 to rotate integrally with the rotary shaft 31. As the rotor 11 rotates, the fan 3 having a plurality of blades 19 attached to the rotor 11 also rotates integrally with the rotor 11. When the fan 3 is rotated, air outside the apparatus is sucked through an opening provided in the housing constituting the computer, and further, the air passes through the housing and passes through the heat sink provided in the housing. By exhausting to the outside of the housing through the mouth, the heat generated from the heating element is radiated to the outside of the computer main body, and the computer main body is cooled.

  Next, the bearing unit 30 used for the motor 1 will be described in more detail.

  The bearing unit 30 that rotatably supports the rotating shaft 31 of the motor 1 described above includes a radial bearing 33 that supports the rotating shaft 31 in the circumferential direction, and the radial bearing 33, as shown in FIGS. 1, 2, and 3. A passage forming member 34 formed outside the bearing 33, a housing 37 in which the passage forming member 34 is accommodated, and a communication passage 50 formed between the passage forming member 34 and the radial bearing 33 are provided.

  The radial bearing 33 is formed in a cylindrical shape from sintered metal. The radial bearing 33 constitutes a dynamic pressure fluid bearing together with the lubricating oil 42 which is a viscous fluid filled in the housing 37, and the dynamic pressure generating grooves 43, 44 is formed.

  As shown in FIG. 4, the dynamic pressure generating grooves 43 and 44 are formed by forming a plurality of V-shaped grooves 43 a and 44 a in the circumferential direction on the inner peripheral surface of the radial bearing 33. The dynamic pressure generating grooves 43 and 44 are formed so that the distal ends of a pair of V-shaped grooves 43 a and 44 a face the rotation direction R <b> 1 of the rotating shaft 31. Here, the dynamic pressure generating grooves 43 and 44 are formed in parallel in the axial direction of the radial bearing 33 having a cylindrical shape, and the dynamic pressure generating grooves 43 are arranged on the shaft exposed side where the shaft is open, The pressure generating groove 44 is formed on the non-shaft exposed side where the shaft is not opened, that is, the thrust bearing side described later. The number and size of the dynamic pressure generating grooves 43 and 44 provided in the radial bearing 33 are appropriately selected depending on the size and length of the radial bearing 33. The radial bearing 33 may be made of brass, stainless steel, or a polymer material. Further, here, a plurality of dynamic pressure generating grooves are formed in a V-shape, but the present invention is not limited to this, and a plurality of V-shaped grooves on the inner peripheral surface are connected in the circumferential direction. May be formed so as to form a so-called herringbone shape.

  The radial bearing 33 formed as a hydrodynamic fluid bearing fills the housing 37 when the rotating shaft 31 inserted through the radial bearing 33 continuously rotates around the central axis CL in the direction of arrow R1 in FIG. The lubricated oil 42 flows through the dynamic pressure generating grooves 43 and 44, and generates a dynamic pressure between the outer peripheral surface of the rotating shaft 31 and the inner peripheral surface of the radial bearing 33 to support the rotating shaft 31 that rotates. . The dynamic pressure generated at this time realizes smooth rotation of the rotating shaft 31.

  As shown in FIGS. 2, 3 and 5, the passage forming member 34 provided on the outer side of the radial bearing 33 has a shape that encloses and surrounds the radial bearing 33 formed in a cylindrical shape. It is made of resin.

  As shown in FIGS. 2 and 5, the passage forming member 34 surrounds a passage forming member main body 35 formed so as to surround the side surface portion 33 a and the bottom surface portion 33 b of the radial bearing 33, and the upper surface portion 33 c of the radial bearing 33. The passage forming member lid portion 36 is formed as described above. A shaft insertion hole 36 a through which the rotation shaft 31 rotatably supported by the radial bearing 33 is inserted is provided in the central portion of the passage forming member lid portion 36.

  A bearing support portion 31 a provided at one end portion in the thrust direction, which is the axial direction of the rotary shaft 31 supported by the radial bearing 33, is rotatably supported at the center portion on the inner surface side of the bottom surface portion of the passage forming member main body 35. A thrust bearing 46 is integrally formed. In the thrust bearing 46, the passage forming member 34 is formed of resin, and is shared as a thrust bearing. The thrust bearing 46 is formed as a pivot bearing that supports the bearing support portion 31a of the rotary shaft 31 that is formed in an arc shape or a tapered tip shape.

  Here, the thrust bearing 46 is formed as a part of the passage forming member 34. However, the thrust bearing is formed independently of the passage forming member and disposed on the bottom surface of the passage forming member. You may make it comprise.

  A claw-shaped restricting portion 35 a that fixes the passage forming member lid portion 36 so as to cover the upper surface portion 33 c of the radial bearing 33 is provided on the circumference of the upper portion of the passage forming member main body 35.

  The passage forming member 34 is made of resin, but may be made of metal, and may be a combination of resin and metal, and the material is not limited. Here, when the passage forming member 34 is made of resin, there is an advantage that the shape can be devised, such as a phase index with the radial bearing, and it is inexpensive. For example, as a resin material used for the passage forming member 34, a fluorine-based synthetic resin such as polyimide, polyamide, and polyacetal, a synthetic resin such as polytetrafluoroethylene Teflon (registered trademark) and nylon, and further, PC (polycarbonate) A synthetic resin such as ABS (acrylonitrile butadiene styrene) may be used.

  A communication path 50 is formed between the path forming member 34 and the radial bearing 33. The communication path 50 communicates one end portion and the other end portion of the rotating shaft 31 protruding from the radial bearing 33 in the thrust direction. That is, the communication path 50 communicates one end side, which is the bottom surface side where the thrust bearing 46 is provided, and the other end side, which is the upper surface side where the shaft insertion hole 36a of the path forming member lid portion 36 is formed.

  As shown in FIGS. 2, 3, 5, 6, and 7, the communication passage 50 includes a first groove formed in the thrust direction on the inner peripheral surface of the passage forming member main body 35 of the passage forming member 34. 51, a second groove 52 formed on the inner surface side of the bottom surface portion of the passage forming member main body 35, and a third groove 53 formed on the inner surface 36b side of the passage forming member lid portion 36. And the passage forming member 34 are formed so as to communicate one end side and the other end side of the radial bearing 33. Here, the first to third grooves 51, 52, 53 are configured to be provided at three substantially equal intervals, but the present invention is not limited to this.

  Further, as shown in FIGS. 3 and 5, a plurality of bearing positioning projections 54 are formed on the inner peripheral surface of the passage forming member main body 35 at substantially equal locations on the circumference. The plurality of bearing positioning projections 54 regulate the position in a plane orthogonal to the axial direction of the radial bearing 33 by contacting the outer peripheral surface of the radial bearing 33, and have a cross-sectional shape orthogonal to the axial direction. All are formed in the axial direction so as to have the same shape. Further, here, the bearing positioning projections 54 are provided at three positions at equal positions on the circumference. However, the present invention is not limited to this, and a plurality of positions may be provided. Any position that can be positioned is acceptable.

  A plurality of slit-like grooves 55 formed in the axial direction (thrust direction) are provided between the bearing positioning projections 54 on the inner peripheral surface of the passage forming member main body 35. In other words, a plurality (three places) of projections 56 formed in the axial direction between the plurality of bearing positioning projections 54 are provided, and the plurality of projections 56 and the plurality of bearing positionings are provided. A plurality (four places) of slit-like grooves 55 are formed between the protrusions 54.

  Since the slit-like groove 55 is formed in a circumferential dimension, that is, the width of the groove is small, it is possible to hold the lubricating oil satisfactorily by capillary action and to hold the lubricating oil. It functions as a viscous fluid holding part. The slit-like groove 55 as the viscous fluid holding portion increases the filling amount of the lubricating oil in the bearing unit 30 and also holds the lubricating oil well by capillary action, and the lubricating oil passes through a shaft insertion hole 41 described later. Prevent leakage to the outside.

Here, the fact that the slit-like groove 55 shown in FIGS. 3 and 5 has a function as a viscous fluid holding portion will be described using the bearing unit 130 of the comparative example shown in FIGS. 8 and 9.
The bearing unit 130 of the comparative example has the same configuration as the above-described bearing unit 30 except for the configuration of the passage forming member and the viscous fluid holding portion formed on the passage forming member. Omitted.

  As shown in FIGS. 8 and 9, the passage forming member 134 of the bearing unit 130 of the comparative example includes a passage forming member main body 135 formed so as to surround the radial bearing 33 and a passage forming member lid portion 36. A plurality of bearing positioning projections 54 and a recess 155 as a viscous fluid filling portion formed in the axial direction between the bearing positioning projections 54 are provided on the inner peripheral surface of the passage forming member main body 135.

  As described above, in the bearing unit 130 of the comparative example, by providing the concave portion 155 as the viscous fluid filling portion, the filling amount of the lubricating oil can be increased, but only a space for filling is provided. The surface of the shaft insertion hole 41, which will be described later, becomes difficult to keep the lubricating oil inside, and depending on the orientation and posture of the bearing unit 130 attached to a device such as a motor or an impact. Holding only by the tension effect makes it difficult to hold and may leak to the outside.

  In contrast to the bearing unit 130 of the comparative example, in the bearing unit 30 to which the present invention is applied, a plurality of slit-like grooves 55 are provided as described above, that is, the width of each groove 55 is formed to be small. In addition, the capillarity of each slit-like groove 55 makes it possible to hold the lubricating oil well and make it difficult to flow out to the outside, and to increase the filling amount of the lubricating oil. It functions as a fluid holding part, and it is possible to prevent the leakage of the lubricating oil and increase the filling amount of the lubricating oil regardless of the mounting posture to the device.

  Here, in the viscous fluid holding portion formed on the inner peripheral surface of the passage forming member, the above-mentioned slit-like grooves are formed in the grooves 55 provided at four positions between the above-described adjacent bearing positioning projections 54. It is not limited. That is, for example, as shown in FIG. 10, five viscous fluid holding portions are provided between the plurality of bearing positioning protrusions 64 formed on the inner peripheral surface of the passage forming member main body 60, respectively, in the axial direction. You may comprise so that it may consist of the some slit-shaped groove | channel 65 formed. Furthermore, for example, as shown in FIG. 11, six viscous fluid holding portions are provided between the plurality of bearing positioning projections 74 formed on the inner peripheral surface of the passage forming member main body 70, respectively, in the axial direction. You may comprise so that it may consist of the some slit-shaped groove | channel 75 formed. Further, the number of slit-like grooves may be increased, and the number of bearing positioning protrusions may be changed as described above.

  As described above, the bearing unit 30 is provided by providing the viscous fluid holding portion including the plurality of slit-like grooves 55, 65, 75 formed in the axial direction on the inner peripheral surfaces of the passage forming members 35, 60, 70. It is possible to increase the filling amount of the lubricating oil filled in the inside in a state in which the lubricating oil is easily retained by capillary action.

  Of the slit-like grooves 55, the grooves 55 formed at positions corresponding to the second and third grooves 52 and 53 described above become the first grooves 51 described above. Here, the three grooves formed at positions corresponding to the second and third grooves 52 and 53 are the first grooves 51, but the present invention is not limited to this, and the slit-shaped grooves are not limited thereto. It is sufficient that at least one of these functions as an axial passage constituting the communication passage 50.

  The communication passage 50 described above includes the first passage 51 a formed in the first groove 51, the second passage 52 a formed in the second groove 52, and the third groove 53. And a third passage 53a formed. Here, the first to third passages 51a, 52a, 53a formed by the first to third grooves 51, 52, 53 are configured to be provided at three substantially equal intervals, respectively. However, it is not limited to this.

  The communication path 50 configured as described above alleviates the decrease in static pressure on the non-opening side by connecting the open side and the non-opening side of the rotating shaft 31 protruding from the radial bearing 33 and short-circuiting the pressures in both regions. is doing. Here, the open side of the rotary shaft 31 (hereinafter referred to as “shaft open side”) refers to the upper surface side of the radial bearing 33, that is, the side where the shaft insertion hole 41 is provided, and the non-open side of the rotary shaft 31. (Hereinafter referred to as “non-shaft open side”) refers to the bottom surface side of the radial bearing 33, that is, the side on which the thrust bearing 46 is disposed.

  Since the communication path 50 communicates the open side and the non-open side of the rotary shaft 31 protruding from the radial bearing 33, when the rotary shaft 31 and the housing 37 rotate relatively and dynamic pressure is generated. In addition, it is possible to prevent the static pressure at the shaft end on the non-shaft opening side, which is the side where the rotating shaft 31 is not opened, from being lowered. Therefore, the communication path 50 can prevent the extrusion of the lubricating oil due to the expansion of the residual air in the housing 37 and the expansion of the air dissolved in the lubricating oil, which is generated when the internal static pressure is reduced. In other words, the communication path 50 can short-circuit the pressures at both ends of the dynamic pressure generating grooves 43 and 44 provided in the radial bearing 33, so that no pressure difference is generated, and thus shaft levitation occurs. There is nothing.

  In addition, the communication passage 50 can circulate the lubricating oil 42 inside the housing 37 when dynamic pressure is generated by the radial bearing 33 that is a hydrodynamic fluid bearing. That is, the lubricating oil 42 is circulated from the inner peripheral side of the radial bearing 33 toward the bottom surface 33b side from the upper surface 33c side, and the communication passage 50 on the outer peripheral side of the radial bearing 33 is directed from the bottom surface 33b side to the upper surface 33c side. Circulated. The communication passage 50 carries the residual air in the lubricating oil from the non-shaft opening side where the thrust bearing is disposed to the shaft opening side which is the side where the shaft insertion hole is provided, along with the circulation of the lubricating oil on the outer peripheral side. It can be discharged from the shaft insertion hole 41 to the outside.

  As shown in FIG. 2, the housing 37 that houses the passage forming member 34 has a shape that encloses and surrounds the substantially cylindrical passage forming member 34, and is formed by integrally molding synthetic resin. It is a member.

  As shown in FIG. 2, the housing 37 includes a cylindrical housing main body 38 and a bottom closing portion constituting one end side portion formed integrally with the housing main body 38 so as to close one end side of the housing main body 38. 39 and an upper closing portion 40 formed integrally with the housing main body 38 constituting the other end side of the housing main body 38. A shaft insertion hole 41 through which the rotation shaft 31 rotatably supported by the radial bearing 33 housed in the housing 37 is inserted is provided at the center of the upper closing portion 40.

  In the housing 37 configured as described above, the synthetic resin material is outsert-molded so as to enclose the substantially cylindrical passage forming member 34, whereby the passage forming member 34 is arranged on the inner peripheral side of the housing main body 38. It is integrally formed. That is, the housing 37 is formed so as to hermetically accommodate the passage forming member 34 that accommodates the radial bearing 33 and has a shaft insertion hole 41 through which the rotary shaft 31 is inserted.

  The synthetic resin material constituting the housing 37 is not particularly limited. However, since the passage forming member 34 is integrally formed in the housing 37, it is preferable to use a synthetic resin material having excellent lubricity. For example, the housing 37 is preferably formed using a fluorine-based synthetic resin such as polyimide, polyamide, or polyacetal, or a synthetic resin such as polytetrafluoroethylene Teflon or nylon. Furthermore, you may use synthetic resins, such as PC (polycarbonate), ABS (acrylonitrile butadiene styrene), and a liquid crystal polymer.

  By the way, in this bearing unit 30, since the housing 37 has a sealed seamless structure together with the radial bearing 33 and the passage forming member 34 except for the shaft insertion hole 36a, the shaft open side protruding from the radial bearing 33 of the rotary shaft 31 and the non-opening side. The shaft opening side is communicated by the communication passage 50, but the portion other than the shaft insertion hole 36a provided in the housing 37 is sealed from the outside. That is, since the bearing unit 30 is provided in the housing 37 in which the communication path 50 is seamlessly formed and sealed from the outside, it is possible to prevent the occurrence of lubricating oil scattering due to an impact. .

  A rotary shaft 31 rotatably supported by a radial bearing 33 disposed in the housing 37 and a thrust bearing 46 provided integrally with the housing 37 is a bearing support portion supported by the thrust bearing 46 of the shaft body 31b. 31a is formed in a circular arc shape or a tapered tip, and a mounting portion 32 to which, for example, the rotor 11 of the motor 1, which is a rotating body, is mounted is provided on the other end side. Here, the shaft body 31b and the mounting portion 32 are formed to have the same diameter.

  As shown in FIG. 2, the rotary shaft 31 has a bearing support portion 31a on one end side supported by a thrust bearing 46, an outer peripheral surface of the shaft portion main body 31b supported by a radial bearing 33, and an attachment portion provided on the other end side. The side 32 protrudes from a shaft insertion hole 41 provided in the upper closing portion 40 of the housing body 38 and is supported by the housing 37.

  Further, the rotary shaft 31 is provided with a groove portion 31c for preventing the shaft from dropping between the bearing support portion 31a and the shaft portion main body 31b. A washer 49 is provided on the passage forming member 34 as a means for preventing the shaft from slipping off so as to correspond to the shaft retaining groove 31c. By engaging the shaft retaining groove 31c and the washer 49, handling during assembly is improved. The washer 49 is made of a polymer material such as nylon, polyamide or polyimide, or a metal such as stainless steel or phosphor bronze.

  By the way, the shaft insertion hole 41 has an inner diameter that is slightly larger than the outer diameter of the shaft body 31b so that the rotation shaft 31 inserted through the shaft insertion hole 41 rotates without slidingly contacting the inner peripheral surface of the shaft insertion hole 41. It is formed with. At this time, the shaft insertion hole 41 has a gap 45 between the inner peripheral surface and the outer peripheral surface of the shaft portion main body 31 b with a gap 45 sufficient to prevent the lubricating oil 42 filled in the housing 37 from leaking from the housing 37. Is formed. Thus, the upper closing portion 40 in which the shaft insertion hole 41 is formed so that the gap 45 is formed between the rotating shaft 31 and the lubricating oil 42 filled in the housing 37 to prevent leakage. The oil seal part is configured.

  A tapered portion 47 is provided on the outer peripheral surface facing the inner peripheral surface of the shaft insertion hole 41 of the rotating shaft 31. The tapered portion 47 is inclined so as to expand a gap 45 formed between the outer peripheral surface of the rotating shaft 31 and the inner peripheral surface of the shaft insertion hole 41 toward the outside of the housing 37. The taper portion 47 forms a pressure gradient in a gap 45 formed by the outer peripheral surface of the rotating shaft 31 and the inner peripheral surface of the shaft insertion hole 41, and allows the lubricating oil 42 filled in the housing 37 to flow inside the housing 37. A force to pull in is generated. That is, in the bearing unit 30, the gap 45 formed between the outer peripheral surface of the rotating shaft 31 and the inner peripheral surface of the shaft insertion hole 41 prevents the lubricating oil 38 from scattering due to the surface tension effect. Since the lubricating oil 42 is drawn into the housing 37 when the rotary shaft 31 rotates, the lubricating oil 42 is surely received in the dynamic pressure generating grooves 43 and 44 of the radial bearing 33 constituted by the dynamic pressure fluid bearing. In this way, a dynamic pressure is generated by the intrusion into the shaft, so that stable support of the rotary shaft 31 is realized, and leakage of the lubricating oil 42 filled in the housing 37 can be prevented.

  In the bearing unit 30 to which the present invention is applied, the lubricating oil 42 which enters the dynamic pressure generating grooves 43 and 44 provided in the radial bearing 33 constituting the dynamic pressure fluid bearing and generates dynamic pressure is as shown in FIG. The housing 37 is filled so as to face the gap 45 formed by the tapered portion 47 formed on the rotary shaft 31 and the inner peripheral surface of the shaft insertion hole 41. That is, the lubricating oil 42 is filled in the gap in the housing 37 and further impregnated in the radial bearing 33 made of sintered metal.

  Here, since the bearing unit 30 is provided with a plurality of slit-like grooves 55 formed in the axial direction on the inner peripheral surface of the passage forming member main body 35, the plurality of slit-like grooves are provided. 55 functions as a viscous fluid holding section, and can increase the filling amount of the lubricating oil 42, and the filled lubricating oil 42 is held in a state where it is difficult to leak and volatilize to the outside due to capillary action. Leakage can be prevented.

The bearing unit 30 can prevent the lubricating oil 42 from being scattered by the surface tension seal by adjusting the gap c of the gap 45 and the height H ₁ of the shaft insertion hole 41, and is positioned in the gap 45 by providing the tapered portion 47. A pressure gradient can be generated in the lubricating oil 42 to generate a force that pulls the lubricating oil 42 into the housing 37, preventing air from being entrained in the lubricating oil 42 and preventing leakage of the lubricating oil 42, and further rotation. A stable rotation of the shaft 31 can be guaranteed. In the bearing unit 30 described above, the tapered portion 47 is provided on the rotating shaft 31 side. However, the tapered portion may be provided on the inner peripheral surface of the shaft insertion hole 41 of the housing 37.

  A process of manufacturing the bearing unit 30 to which the present invention configured as described above is applied will be described.

  In order to manufacture the bearing unit 30 according to the present invention, temporary assembly is performed by attaching the passage forming member 34 to the outside of the radial bearing 33. When the radial bearing 33 and the passage forming member 34 are temporarily assembled, as shown in FIG. 12, a washer 49 that is a shaft retaining means for the rotary shaft 31 is attached to the passage forming member main body 35. Next, the passage forming member main body 35 and the passage forming member lid portion 36 are attached to the radial bearing 33 which is a hydrodynamic bearing. At this time, a thrust bearing 46 is integrally formed in the passage forming member main body 35. A communication path 50 is formed between the path forming member 34 and the radial bearing 33.

  Next, the temporarily assembled radial bearing 33 and the passage forming member 34 are attached to the mold, and as shown in FIG. 13, any of the above-described synthetic resins is provided around the outer periphery of the temporarily assembled radial bearing 33 and the passage forming member 34. The housing 37 is formed by outsert molding. At this time, when the housing 37 is outsert-molded, the passage forming member 34 is integrated into the interior of the housing 37 and is integrally formed on the top and bottom of the cylindrical housing body 38 and the bottom closing portion. It is clamped by the part 39, and its mounting position is fixed. Further, when the housing 37 is outsert molded, the synthetic resin does not flow into the communication passage 50 between the passage forming member 34 and the radial bearing 33 because the passage 37 is blocked by the passage forming member 34.

  Next, the rotating shaft 31 is inserted into the shaft insertion hole 41 provided in the upper closing portion 40 and inserted into the housing 37. At this time, the rotating shaft 31 is inserted into the housing 37 by causing the bearing support portion 31 a to contact the thrust bearing 46 and passing through the radial bearing 33. The rotating shaft 31 supported by the thrust bearing 46 and the radial bearing 33 is rotatably supported in the housing 37.

  When the rotary shaft 31 is inserted into the housing 37, the housing 37 is filled with lubricating oil 42. For filling the lubricating oil 42, the housing 37 in which the rotary shaft 31 is inserted is put into a filling tank in which the lubricating oil is accommodated. Next, the filling tank in which the housing is put is vacuumed by a vacuum device. Thereafter, the filling tank sucked in vacuum is taken out into the atmosphere, whereby the housing 37 is filled with the lubricating oil 42.

  At this time, the lubricating oil 42 is prevented from leaking from the inside of the shaft insertion hole 41 to the outside of the housing 37 when expanded due to a temperature change, and when it is contracted due to a temperature change, the lubricating oil 42 is inserted into the shaft 31. Filling is performed so that insufficient filling of the gap 45 formed between the holes 41 does not occur. That is, the change in the oil level height of the lubricating oil 42 due to the temperature change is set to be in the range in the shaft insertion hole 41.

  By filling the housing 37 with the lubricating oil 42 by vacuum suction using a vacuum device, the pressure inside the housing 37 becomes lower than the outside. As a result, the lubricating oil 42 is prevented from easily leaking from the housing 37.

  In the bearing unit 30 according to the present invention, since the radial bearing 33 is formed of sintered metal, the radial bearing 33 is filled with the lubricating oil 42, and the dynamic pressure is generated by the rotation of the rotating shaft 31. The generating grooves 43 and 44 are also filled with the lubricating oil 42. That is, the lubricating oil 42 fills all the gaps in the housing 37.

  In the above-described bearing unit, the housing is formed of a synthetic resin molded body, but the housing is not limited to the synthetic resin, and a synthetic resin mixed with a metal material that can be molded using a mold apparatus or other molding material is used. It may be formed.

  The bearing unit 30 configured as described above is very useful for preventing leakage of the lubricating oil, but is generated when the shaft rotates and the residual oil in the lubricating oil or the dissolved air is expanded due to the expansion of the lubricating oil. This solves the problem of a so-called shaft piece open type hydrodynamic bearing unit having a seamless resin housing, which has a drawback of being easily generated.

  That is, the bearing unit 30 is provided with a communication passage 50 that short-circuits the pressures at both ends of the radial bearing, and the passage is non-axially opened without the non-axial opening side-passage-housing outer-shaft opening side. The side-communication path-shaft opening side is formed, and the passage forming member 34 having the communication path 50 is covered with a seamless housing 37.

  That is, this bearing unit 30 is provided with a passage forming member 34, provided with a communication passage 50 whose path is a bearing lower end-passage-bearing upper end at the upper end and lower end of the radial bearing 33, and is a lower end on the sealed side. Since the decrease in static pressure on the non-shaft opening side can be mitigated, leakage of lubricating oil due to pushing up of residual air can be prevented.

  Further, in the bearing unit 30, the section of the third passage 53a provided on the shaft opening side of the communication passage 50 is made larger than the section of the first passage 51a, and the section of the passage becomes larger toward the shaft opening side. Therefore, the residual air mixed in the lubricating oil 42 filled in the housing 37 is sent from the communication passage 50 to the shaft opening side where the shaft insertion hole is provided, and the housing 37 is connected to the shaft 37 through the shaft insertion hole. Good discharge to the outside.

  Further, the bearing unit 30 is configured such that the rotary shaft 31 is exposed only at one end on the shaft insertion hole 41 side, and a portion other than a slight gap of the shaft insertion hole 41 is seamlessly covered by the housing 37 to the outside of the housing. This path is maintained with only a slight gap between the rotating shaft 31 and the housing 37, so that the lubricating oil oozes out from the joint when the member filled with the lubricating oil 42 is joined. The fear can be prevented, the scattering of lubricating oil due to impact can be prevented, and good lubricating performance can be obtained.

  The bearing unit 30 to which the present invention is applied can prevent a decrease in pressure in the housing 37 due to the relative rotation between the rotating shaft 31 and the housing 37 by the communication path 50, and the lubricating oil 42 filled in the housing 37. Since the residual air mixed in the viscous fluid can be discharged well, the lubricating oil 42 inside the housing 37 is pushed out of the bearing unit due to the expansion of the residual air due to the pressure drop in the housing 37. In the state where the lubricating oil is easily retained by the viscous fluid retaining portion formed by the plurality of slit-like grooves 55 formed on the inner peripheral surface of the passage forming member 34. The filling amount can be increased, the lubricating oil can be reliably held for a long period of time, and good rotation performance can be maintained.

  Further, in the bearing unit 30 to which the present invention is applied, even when a sintered metal having a porous material is used as the radial bearing 33, the residual air dissolved in the lubricating oil conventionally filled around the sintered metal is used. However, it is difficult to completely discharge the residual air dissolved in the lubricating oil filled around the radial bearing 33. Since the leakage phenomenon can be prevented, good lubrication performance can be maintained over a long period of time even when a sintered metal having a porous structure is used, and an inexpensive configuration can be achieved.

  In the bearing unit 30 described above, the communication path 50 is formed by the first to third grooves 51, 52, 53 provided on the path forming member 34 side. May be provided on the radial shaft 33 side. Furthermore, the communication path constituting the bearing unit 30 is a combination of the first to third grooves 51 to 53 provided on the above-described passage forming member 34 side and the first to third grooves provided on the radial bearing 33 side. You may comprise so that it may be formed by a thing.

  The motor 1 to which the present invention is applied includes a bearing unit 30 that rotatably supports the rotor 11 with respect to the stator 12, thereby preventing leakage of the lubricating oil and filling the filling amount in a state in which the lubricating oil is easily retained. It is possible to increase and maintain good rotation performance over a long period of time.

  The bearing unit according to the present invention can be used not only as a bearing of a cooling fan motor of a heat dissipation device or a spindle motor of a disk drive, but also as a bearing of various motors.

  Furthermore, the bearing unit according to the present invention can be widely used not only for a motor but also for a mechanism including a rotating shaft and a mechanism for supporting a component rotating with respect to the shaft.

It is sectional drawing which shows the structure of the motor to which this invention is applied. It is XX sectional drawing shown in FIG. 3 of the bearing unit to which this invention is applied. It is YY sectional drawing shown in FIG. 2 of the bearing unit to which this invention is applied. It is a perspective view which shows the dynamic pressure generation groove formed in the internal peripheral surface of a radial bearing. It is a figure which shows the viscous fluid holding | maintenance part formed in the internal peripheral surface of a channel | path formation member, and a 2nd groove | channel, and is YY sectional drawing of the channel | path formation member shown in FIG. It is a figure which shows the 3rd groove | channel formed in the channel | path formation member cover part, and is sectional drawing of a channel | path formation member cover part. It is a figure which shows the 3rd groove | channel formed in the channel | path formation member cover part, and is a bottom view of a channel | path formation member cover part. It is sectional drawing which shows the bearing unit of the comparative example for comparing with this invention. It is sectional drawing which shows the ZZ cross section shown in FIG. 8 of the bearing unit of a comparative example. It is sectional drawing which shows the other example of the viscous fluid holding | maintenance part formed in the internal peripheral surface of a channel | path formation member. It is sectional drawing which shows the further another example of the viscous fluid holding | maintenance part formed in the internal peripheral surface of a channel | path formation member. It is a figure explaining the process of carrying out temporary assembly in the process of manufacturing the bearing unit according to the present invention. It is a figure explaining the process of outsert-molding a housing in the process of manufacturing the bearing unit concerning the present invention. It is sectional drawing which shows the bearing unit used conventionally.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Motor, 11 Rotor, 12 Stator, 13 Stator yoke, 17 Rotor yoke, 30 Bearing unit, 31 Rotating shaft, 33 Radial bearing, 34 Passage formation member, 37 Housing, 38 Housing main body, 39 Bottom closing part, 40 Upper closing part, 41 shaft insertion hole, 42 lubricating oil, 43, 44 dynamic pressure generating groove, 45 air gap, 46 thrust bearing, 47 tapered portion, 50 communication path, 51 first groove, 52 second groove, 53 third groove, 51a 1st passage, 52a 2nd passage, 53a 3rd passage, 54 bearing positioning projection part, 55 slit-like groove, 56 projection part

Claims (2)

A radial bearing for supporting the shaft in the circumferential direction;
A thrust bearing that supports one end of the shaft in the thrust direction;
A passage forming member provided outside the radial bearing and the thrust bearing;
A housing having a shaft insertion hole through which the shaft is inserted, and formed so as to seal and store the passage forming member;
A viscous fluid filled in the housing;
A plurality of passages formed at equal intervals between the passage forming member and the radial bearing, and communicating with the one end side and the other end side in the thrust direction of the shaft protruding from the radial bearing;
On the inner peripheral surface of the passage forming member , a plurality of holes are formed on the inner peripheral surface of the passage forming member at equal intervals to abut on the outer peripheral surface of the radial bearing and regulate positions in a plane orthogonal to the axial direction. As a viscous fluid holding portion for holding the viscous fluid between the bearing positioning projections, a plurality of axial slits are formed by the projections formed between the bearing positioning projections on the inner peripheral surface of the passage forming member. Groove is formed ,
A bearing unit in which at least one of the plurality of slit-shaped grooves serves as the communication path . In a motor including a bearing unit that rotatably supports a rotor with respect to a stator,
The bearing unit includes a radial bearing that supports the shaft in a circumferential direction;
A thrust bearing that supports one end of the shaft in the thrust direction;
A passage forming member provided outside the radial bearing and the thrust bearing;
A housing having a shaft insertion hole through which the shaft is inserted, and formed so as to seal and store the passage forming member;
A viscous fluid filled in the housing;
A plurality of passages formed at equal intervals between the passage forming member and the radial bearing, and communicating with the one end side and the other end side in the thrust direction of the shaft protruding from the radial bearing;
On the inner peripheral surface of the passage forming member , a plurality of holes are formed on the inner peripheral surface of the passage forming member at equal intervals to abut on the outer peripheral surface of the radial bearing and regulate positions in a plane orthogonal to the axial direction. As a viscous fluid holding portion for holding the viscous fluid between the bearing positioning projections, a plurality of axial slits are formed by the projections formed between the bearing positioning projections on the inner peripheral surface of the passage forming member. Groove is formed ,
A motor in which at least one of the plurality of slit-shaped grooves serves as the communication path .

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