Patent Publication Number: US-2019199171-A1

Title: Motor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority under 35 U.S.C. § 119 to Japanese Application No. 2017-252099 filed on Dec. 27, 2017 the entire content of which is incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a motor. 
     BACKGROUND 
     A technique to prevent oil in a bearing of a motor from leaking has been known. Some motors include a stationary member that includes a radial bearing and a rotor includes a rotary shaft that is rotatably supported by the radial bearing and protrudes downward of the stationary member. 
     However, a radial bearing having a small volume, for example, can contain only a small amount of a lubricating oil. For this reason, a radial bearing having a small volume is likely to suffer influence, for example, the shortening of useful life, when the lubricating oil inside the radial bearing is reduced by the scattering of the lubricating oil resulting from the rotation of the motor, and other causes. 
     SUMMARY 
     An exemplary motor of at least one embodiment includes a rotary portion; a bearing portion; and a stationary portion. The rotary portion includes a shaft having a center on a vertically extending central axis. The bearing portion rotatably supports the shaft. The stationary portion includes a stator. The bearing portion is radially outward of the shaft and includes a sleeve bearing that contains a lubricating oil; and a housing radially outward of the sleeve bearing. The stator includes a stator core that is radially outward of the housing; and an insulator that covers at least part of the stator core. The insulator includes an upper insulating portion that covers an upper face of the stator core; a connecting portion that extends radially inward from the upper insulating portion; and an insulator inclined portion that is inclined in a direction away from the central axis, downward from a radially inner end portion of the connecting portion. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a fan motor to which a motor according to at least one embodiment of the present disclosure is applied. 
         FIG. 2  is a vertical sectional view of the motor according to at least one embodiment of the present disclosure. 
         FIG. 3  is a sectional view of an upper portion of a bearing portion and surroundings in an enlarged manner according to at least one embodiment of the present disclosure. 
         FIG. 4  is a plan view of a second member according to at least one embodiment of the present disclosure. 
         FIG. 5  is a perspective view of a housing according to at least one embodiment of the present disclosure. 
         FIG. 6  is a view of a circulation model of a lubricating oil contained in a sleeve bearing according to at least one embodiment of the present disclosure. 
         FIG. 7  is a horizontal sectional view of the housing according to at least one embodiment of the present disclosure. 
         FIG. 8  is a schematic view of a position to apply an oil repellent agent according to at least one embodiment of the present disclosure. 
         FIG. 9  is a schematic sectional view of a motor of at least one embodiment of the present disclosure. 
         FIG. 10  is a schematic sectional view of a motor of at least one embodiment of the present disclosure. 
         FIG. 11  is a schematic sectional view of a motor of at least one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, at least one embodiment of the present disclosure will be described with reference to the drawings.  FIG. 1  is an exploded perspective view of a fan motor to which a motor  100  according to at least one embodiment of the present disclosure is applied.  FIG. 1  shows part of the fan motor in an enlarged manner. In  FIG. 1 , the motor  100  is attached to a blade portion  200 . The blade portion  200  is fixed to a rotary portion  101  of the motor  100  and rotates along with the rotation of the rotary portion  101 . Note that the motor  100  may be applied to applications other than the fan motor. The rotary portion  101  may be equipped with a member other than blades. 
     In the present Specification, “axial”, “axially”, and “axial direction” refer to a direction parallel with a central axis C of the motor  100 , in  FIG. 2 ; “radial”, “radially”, and “radial direction”, a direction orthogonal to the central axis C; “circumferential”, “circumferentially”, and “circumferential direction”, a direction extending along an arc about the central axis C. In addition, in the present Specification, shapes and positional relations of the portions will be described on the assumption that the axial direction is equivalent to the vertical direction and the side on which the blade portion  200  is attached to the motor  100  is the upper side. One of ordinary skill in the art would understand that the definition of the vertical direction is not intended to limit the direction in which the motor  100  is used. 
       FIG. 2  is a vertical sectional view of the motor  100  according to at least one embodiment of the present disclosure. In  FIGS. 1 and 2 , the motor  100  includes a rotary portion  101  and a stationary portion  102 . The motor  100  is a so-called outer rotor-type motor. 
     The rotary portion  101  includes a shaft  1 . The shaft  1  has a center on the vertically extending central axis C. In at least one embodiment, the shaft  1  is a columnar member comprising a metal. The shaft  1  may however have a different shape such as a cylindrical shape, for example. The shaft  1  may comprise a material other than a metal. In at least one embodiment, the blade portion  200 , in  FIG. 1 , is fixed to an upper end of the shaft  1 . 
     The rotary portion  101  further includes a rotor holder  2  and a magnet  3 . The rotor holder  2  includes a rotor cylinder portion  20  and a rotor lid portion  21 . The rotor cylinder portion  20  and the rotor lid portion  21  are formed of a single metal member. The rotor cylinder portion  20  is cylindrical about the central axis C. The rotor lid portion  21  is located at an upper end portion of the rotor cylinder portion  20  and is annular about the central axis C. A circular opening  22  is provided in an upper face of the rotor holder  2 . 
     In at least one embodiment, the rotor holder  2  is fixed to the blade portion  200 . Since the blade portion  200  is fixed to the shaft  1 , the rotor holder  2  is fixed to the shaft  1  as a consequence. That is, the rotor holder  2  and the shaft  1  rotate integrally. Specifically, a boss portion  201  which has a lidded cylindrical shape and is open downward is provided on a central portion of the blade portion  200 . The rotor cylinder portion  20  is housed and fixed inside the boss portion  201 . The method of fixing the rotor cylinder portion  20  and the boss portion  201  is not particularly limited. For example, the fixation may be achieved by press-fitting or bonding. The rotor holder  2  may be directly fixed to the shaft  1  with the size of the opening  22  being reduced. The rotor holder  2  may be indirectly fixed to the shaft  1  by means of an attachment member to be fixed to the shaft  1 . 
     The magnet  3  is fixed to an inner peripheral surface of the rotor holder  2 . Specifically, the magnet  3  is fixed to the inner peripheral surface of the rotor cylinder portion  20  using adhesive, for example. In at least one embodiment, the magnet  3  is annular about the central axis C. The magnet  3  may alternatively be formed of a plurality of magnet pieces arranged circumferentially at intervals about the central axis C. 
     The stationary portion  102  includes a stator  4  and a bearing portion  5 . The stator  4  is annular about the central axis C. The stator  4  is disposed radially inward of the magnet  3 . The stator  4  is an armature that generates magnetic flux in accordance with a drive current. The stator  4  includes a stator core  40  and an insulator  41 . The stator  4  further includes a coil  42 . 
     The stator core  40  is a magnetic body. The stator core  40  is formed by stacking electrical steel sheets for example. The stator core  40  is disposed radially outward of the housing  51 . The housing  51  will be described later. The stator core  40  includes an annular core back  40   a  and a plurality of teeth  40   b.  An inner peripheral surface of the core back  40   a  is fixed to the bearing portion  5 . The plurality of teeth  40   b  protrude radially outward from the core back  40   a.  The plurality of teeth  40   b  are arranged circumferentially about the central axis C at intervals. The plurality of teeth  40   b  are arranged circumferentially at equal intervals. 
     The insulator  41  covers at least part of the stator core  40 . The insulator  41  is an insulating body. As the material for the insulator  41 , a resin is used, for example. The coil  42  is formed by winding a conductive wire around each of the teeth  40   b  with the insulator  41  in between. The stator  4  includes a plurality of the coils  42 . 
     The bearing portion  5  rotatably supports the shaft  1 . The bearing portion  5  includes a sleeve bearing  50  and a housing  51 . The sleeve bearing  50  contains lubricating oil. The sleeve bearing  50  is a sintered body formed by sintering a metal powder, for example. The sleeve bearing  50  is a porous member and has a plurality of fine holes containing the lubricating oil therein. The sleeve bearing  50  is cylindrical about the central axis C. The sleeve bearing  50  is disposed radially outward of the shaft  1 . The shaft  1  is inserted through the cylindrical sleeve bearing  50 . 
     The housing  51  is disposed radially outward of the sleeve bearing  50 . The housing  51  is cylindrical about the central axis C. The sleeve bearing  50  is placed inside the housing  51  and fixed to the housing  51 . The sleeve bearing  50  is fixed to an inner peripheral surface of the housing  51  by press-fitting, for example. A lower end portion of the housing  51  is closed. In at least one embodiment, the housing  51  is part of the same member as that of a base portion  6  expanding radially from the central axis C, and a lower face of the housing  51  is closed by part of the base portion  6 . However, the lower face side of the housing  51  may be closed by a member different from the base portion  6 . The shaft  1  rotates while being in contact with a thrust plate  7 , which is disposed in a lower portion of the housing  51 . In at least one embodiment, the lubricating oil is in the axial gap between the shaft  1  and the thrust plate  7 . 
     A rotational torque is generated between the magnet  3  and the stator  4  by supplying the drive current to the stator  4 . This causes the rotor holder  2  to rotate relative to the stator  4 . The rotor holder  2  rotates together with the shaft  1  about the central axis C. In at least one embodiment, the blade portion  200  rotates about the central axis C along with the rotation of the rotor holder  2 . 
       FIG. 3  is a sectional view of an upper portion of the bearing portion  5  and surroundings in an enlarged manner according to at least one embodiment.  FIG. 3  is an enlarged view of part of  FIG. 2 . In  FIG. 3 , the shaft  1  holds a first member  8 . The first member  8  is disposed above the sleeve bearing  50 . Specifically, the first member  8  is disposed axially away from the sleeve bearing  50 . The first member  8  expands radially outward from the outer peripheral surface of the shaft  1 . 
     Specifically, the first member  8  is a flat plate member that is annular about the central axis C. In at least one embodiment, the first member  8  has a circular outer periphery in a plan view as viewed in the axial direction. However, the first member  8  may have an outer periphery of another shape such as a polygonal shape or an elliptical shape in the plan view as viewed in the axial direction. In at least one embodiment, the first member  8  comprises a metal and is press-fitted onto the shaft  1 . However, the first member  8  may be formed of a material other than a metal, such as a resin. The first member  8  may be fixed to the shaft  1  using adhesive or the like. When the lubricating oil leaks from inside the sleeve bearing  50  and moves upward along the shaft  1 , the first member  8  helps to prevent the lubricating oil from scattering due to the rotation of the shaft  1 . 
     The housing  51  holds a second member  9 . The second member  9  is disposed above the sleeve bearing  50  and below the first member  8 . The second member  9  may be disposed axially away from the sleeve bearing  50 . In at least one embodiment, the second member  9  is disposed as close as possible to the sleeve bearing  50 . The second member  9  may be in contact with the sleeve bearing  50 . The first member  8  and the second member  9  axially face each other with a gap in between. 
     The second member  9  expands radially inward from the inner peripheral surface of the housing  51 .  FIG. 4  is a plan view of the second member  9  according to at least one embodiment. In  FIGS. 3 and 4 , the second member  9  is a flat plate member that is annular about the central axis C. In at least one embodiment, the second member  9  has a circular outer periphery in a plan view as viewed in the axial direction. However, the second member  9  may have an outer periphery of another shape such as a polygonal shape or an elliptical shape in the plan view as viewed in the axial direction. In at least one embodiment, the second member  9  comprises a metal. However, the second member  9  may be formed of another material such as a resin. 
     In  FIG. 4 , the second member  9  includes a first hole  91  and at least one second hole  92 . The first hole  91  axially penetrates therethrough and is circular about the central axis C. However, the shape of the first hole  91  is not limited to a circular shape, but may be another shape such as polygonal shape or an elliptical shape. The first hole  91  is a hole through which to insert the shaft  1 . 
     The second hole  92  is disposed radially outward of the first hole  91 . The second hole  92  axially penetrates therethrough. In at least one embodiment, the second member  9  includes a plurality of the second holes  92 . The plurality of second holes  92  are arranged circumferentially at intervals about the central axis C. Specifically, the plurality of second holes  92  are arranged circumferentially at equal intervals. In at least one embodiment, each of the second holes  92  is circular. However, each second hole  92  may have another shape such as a polygonal shape or an elliptical shape. Each second hole  92  may be arranged concentrically in part in the circumferential direction. In addition, each second hole  92  may have a cut shape cutting inward from an outer edge of the second member  9 . 
     Since the second member  9  covers the upper side of the sleeve bearing  50 , vaporization of the lubricating oil contained in the sleeve bearing  50  is suppressed. In addition, since the second holes  92  are provided in the second member  9 , the lubricating oil repelled by the first member  8  or an insulator inclined portion  413  of the insulator  41  can be returned into the sleeve bearing  50  through the second holes  92 . Note that the second member  9  is disposed above the sleeve bearing  50  and below the insulator inclined portion  413 . The insulator inclined portion  413  will be described later. 
       FIG. 5  is a perspective view of the housing  51  according to at least one embodiment. In  FIGS. 3 and 5 , the housing  51  includes a first cylinder portion  511  and a second cylinder portion  512 . The first cylinder portion  511  and the second cylinder portion  512  are cylindrical about the central axis C. The first cylinder portion  511  radially faces the sleeve bearing  50 . The second cylinder portion  512  is disposed above the first cylinder portion  511 , and has an inner diameter larger than that of the first cylinder portion  511 . The difference in inner diameter between the first cylinder portion  511  and the second cylinder portion  512  provides an upper face  511   a  of the first cylinder portion  511  in the housing  51 . The second member  9  is disposed on the upper face  511   a  of the first cylinder portion  511 . The upper face  511   a  is usable to position the second member  9  and to easily attach the second member  9  to the housing  51 . 
     In  FIG. 3 , the insulator  41  includes an upper insulating portion  411 , a connecting portion  412 , and the insulator inclined portion  413 . The upper insulating portion  411  covers an upper face of the stator core  40 . In at least one embodiment, the upper insulating portion  411  has an annular portion which covers the core back  40   a.  The connecting portion  412  extends radially inward from the upper insulating portion  411 . In at least one embodiment, the connecting portion  412  is annular about the central axis C, and is connected to the annular portion of the upper insulating portion  411 . The insulator inclined portion  413  is inclined in a direction away from the central axis C, downward from a radially inner end portion of the connecting portion  412 . In at least one embodiment, the insulator inclined portion  413  is over the entire periphery in the circumferential direction about the central axis C. However, the insulator inclined portion  413  may be configured to be provided partially in the circumferential direction. The shapes of the upper insulating portion  411  and the connecting portion  412  may be changed in conformity with the configuration of the insulator inclined portion  413 . In at least one embodiment, the insulator inclined portion  413  forms an inner peripheral surface of a cylindrical portion provided downward of the connecting portion  412 . 
     The insulator inclined portion  413  may be a planar surface or a curved surface. The insulator inclined portion  413  may have both of a planar surface and a curved surface. The radially opposite surface of the insulator inclined portion  413  is parallel with the axial direction. However, the radially opposite surface of the insulator inclined portion  413  may be an inclined surface which is inclined relative to the axial direction. This inclined surface may be parallel with the insulator inclined portion  413 . Alternatively, the insulator inclined portion  413  may be a surface having a step shape, which is at least partially stepwise. 
     The insulator inclined portion  413  helps to return the lubricating oil having scattered along with the rotation of the shaft  1  into the sleeve bearing  50  by causing the lubricating oil to hit the insulator inclined portion  413 . In addition, in a case where the motor  100  is arranged in such an orientation that the axial direction becomes horizontal, the lubricating oil is returned into the sleeve bearing  50  along the insulator inclined portion  413  by utilizing the weight of the lubricating oil itself. In other words, the lubricating oil which has hit the insulator inclined portion  413  is prevented from falling down with the weight of the lubricating oil from an end portion of the insulator inclined portion  413  on the axially opposite side to that where the sleeve bearing  50  is provided. In at least one embodiment, the insulator inclined portion  413  and the second cylinder portion  512  are placed radially over each other. This arrangement helps to prevent the lubricating oil from scattering with the second cylinder portion  512  in addition to the insulator inclined portion  413 , and thus to reduce the possibility of leakage of the lubricating oil outside the housing  51 . 
     At least part of the insulator inclined portion  413  may be placed axially over an upper face of the sleeve bearing  50 . In at least one embodiment, the insulator inclined portion  413  is placed axially over a radially outer end of the sleeve bearing  50 . In at least one embodiment, a lower end of the insulator inclined portion  413  is located downward of the first member  8  and be located upward of the second member  9 . The arrangement helps to cause the lubricating oil repelled by the first member  8  to hit the insulator inclined portion  413  and be directed to the second member  9 . In at least one embodiment, the first member  8  is located above a lower end of the insulator inclined portion  413  and above the sleeve bearing  50 . This arrangement helps to cause the lubricating oil repelled by the first member  8  to hit the insulator inclined portion  413  and be returned into the sleeve bearing  50 . 
     In at least one embodiment, the lower end of the insulator inclined portion  413  is in contact with an upper face of the second member  9 . This arrangement helps to easily fix the second member  9  to the housing  51  by pressing the second member  9  with the insulator inclined portion  413 . However, the second member  9  may be fixed to the housing  51  by press-fitting or bonding, for example. In this case, the lower end of the insulator inclined portion  413  may face the second member  9  axially with a gap in between. In this case as well, the insulator inclined portion  413  can suppress the inclined placement of the second member  9  relative to the radial direction. 
     According to at least one embodiment, the lubricating oil contained in the sleeve bearing  50  circulates in accordance with a model shown by arrows in  FIG. 6 .  FIG. 6  is a diagram of the circulation model of the lubricating oil contained in the sleeve bearing  50  according to at least one embodiment. The arrow S in  FIG. 6  indicate the lubricating oil leaked from inside the sleeve bearing  50  to the inner peripheral surface side of the sleeve bearing  50  along with the rotation of the shaft  1  moves along the surface of the shaft  1  to the upper portion of the shaft  1 . In this event, the lubricating oil passes through the first hole  91 . In  FIG. 3 , the shaft  1  has a groove portion  10  in its outer peripheral surface. The groove portion  10  is radially depressed. The shape of the groove portion  10  may be a V shape, a U shape, or the like. The groove portion  10  radially faces the inner peripheral surface which constitutes the first hole  91  of the second member  9  with a gap in between. This allows the lubricating oil which leaks from inside the sleeve bearing  50  and runs on the shaft  1  to be held by the groove portion  10  thanks to the action of surface tension. Accordingly, the amount of the lubricating oil to scatter along with the rotation of the shaft  1  is reduced. 
     The arrow T in  FIG. 6  indicates the lubricating oil having moved to the upper portion of the shaft  1  scatters due to the rotation of the shaft  1  and hits the first member  8  or the insulator inclined portion  413  to be directed toward the second member  9 . The arrow U in  FIG. 6  indicates the lubricating oil directed toward the second member  9  passes through the second hole  92  and returns into the sleeve bearing  50 . The arrow V in  FIG. 6  indicates the lubricating oil having returned into the sleeve bearing  50  again leaks toward the inner peripheral surface side of the sleeve bearing  50  and is positioned between the sleeve bearing  50  and the shaft  1  to reduce friction. Since the cycle of the arrows S to V is repeated, reduction of the lubricating oil inside the sleeve bearing  50  is suppressed. Consequently, the useful life of the sleeve bearing  50  is increased. 
     In at least one embodiment, at least the lower end portion of the first member  8  is located radially inward of the insulator  41 . In at least one embodiment, at least the lower end portion of the first member  8  faces the insulator  41  radially. In at least one embodiment, at least the lower end portion of the first member  8  is located radially inward of the insulator inclined portion  413 . This arrangement helps to suppress excessive increase in axial distance between the first member  8  and the second member  9 . Accordingly, the lubricating oil scattering along with the rotation of the shaft  1  is efficiently returned to the sleeve bearing  50  through the second hole  92 . In at least one embodiment, as in  FIG. 3 , the entirety of the first member  8  is located radially inward of the insulator  41 . 
     Next, a mode regarding the positional relations of the first hole  91  and the second hole  92  with the other members will be described according to at least one embodiment.  FIG. 7  is a horizontal sectional view of the housing  51  according to at least one embodiment. In  FIGS. 5 and 7 , the inner peripheral surface of the first cylinder portion  511  includes a housing depressed portion  513  which is depressed radially. The housing depressed portion  513  extends axially. At the position where the housing depressed portion  513  is provided, the inner peripheral surface of the first cylinder portion  511  and the outer peripheral surface of the sleeve bearing  50  radially face each other with a gap in between. In at least one embodiment, the second hole  92  is located upward of a radially outer end surface of the sleeve bearing  50 . In at least one embodiment, the second hole  92  and the radially outer end surface of the sleeve bearing  50  are placed axially over each other. This arrangement helps to guide the lubricating oil having passed through the second hole  92  to the radial gap between the sleeve bearing  50  and the housing  51 . The lubricating oil having entered between the sleeve bearing  50  and the housing  51  can be returned into the sleeve bearing  50 . Accordingly, reduction of the lubricating oil in the sleeve bearing  50  is suppressed. 
     In at least one embodiment, the region where the second hole  92  is placed axially over the sleeve bearing  50  is not too large. For example, in at least one embodiment, part of the opening portion of the second hole  92  is placed over the sleeve bearing  50 . This arrangement helps to efficiently prevent the lubricating oil from vaporizing from the sleeve bearing  50  with the second member  9 . 
     In  FIG. 3 , the sleeve bearing  50  has a first bearing inclined portion  501  which increases in axial height radially from outside to inside, on a radially outer side of the upper end portion. The first bearing inclined portion  501  may be a planar surface or a curved surface. The first bearing inclined portion  501  may have both of a planar surface and a curved surface. In at least one embodiment, the first bearing inclined portion  501  is provided over the entire periphery in the circumferential direction. In at least one embodiment, the second hole  92  is located upward of the first bearing inclined portion  501 . In at least one embodiment, the second hole  92  and the first bearing inclined portion  501  are placed axially over each other. The entirety of the second hole  92  may be placed axially over the first bearing inclined portion  501 . Part of the second hole  92  may be placed axially over the first bearing inclined portion  501 . In at least one embodiment, an upper end of the first bearing inclined portion  501  is placed axially over the second hole  92 . 
     According to at least one embodiment, the lubricating oil having passed through the second hole  92  is guided to the first bearing inclined portion  501 . The lubricating oil having been guided to the first bearing inclined portion  501  can return into the sleeve bearing  50  directly, or after entering the radial gap between the sleeve bearing  50  and the housing  51 . Accordingly, reduction of the lubricating oil in the sleeve bearing  50  is suppressed. 
     In  FIG. 3 , the sleeve bearing  50  has a second bearing inclined portion  502  which increases in axial height radially from inside to outside, on a radially inner side of the upper end portion thereof. The second bearing inclined portion  502  may be a planar surface or a curved surface. The second bearing inclined portion  502  may have both of a planar surface and a curved surface. In at least one embodiment, the second bearing inclined portion  502  is provided over the entire periphery in the circumferential direction. In at least one embodiment, an upper end of the second bearing inclined portion  502  is located radially outward of the first hole  91 . This arrangement helps to suppress passing of the lubricating oil having leaked from inside the sleeve bearing  50  through the second member  9  via the first hole  91 . This arrangement also helps to insert the shaft  1  into the hole of the sleeve bearing  50  with the second bearing inclined portion  502  and to insert the shaft  1  into the sleeve bearing  50 . 
     In  FIG. 3 , the first cylinder portion  511  has a housing inclined portion  514  which increases in axial height radially from inside to outside, on a radially inner side of the upper end portion thereof. The housing inclined portion  514  may be a planar surface or a curved surface. The housing inclined portion  514  may have both of a planar surface and a curved surface. In at least one embodiment, the housing inclined portion  514  is provided over the entire periphery in the circumferential direction. In at least one embodiment, the housing inclined portion  514  is located downward of the second hole  92 . In at least one embodiment, the second hole  92  and the housing inclined portion  514  are placed axially over each other. The entirety of the second hole  92  may be placed axially over the housing inclined portion  514 . Part of the second hole  92  may be placed axially over the housing inclined portion  514 . 
     According to at least one embodiment, the lubricating oil having passed through the second hole  92  is guided to the housing inclined portion  514 . The lubricating oil having been guided to the housing inclined portion  514  can return into the sleeve bearing  50  directly, or after entering the radial gap between the sleeve bearing  50  and the housing  51 . Accordingly, reduction of the lubricating oil in the sleeve bearing  50  is suppressed. 
     In  FIG. 3 , a radially inner end of the lower end of the insulator inclined portion  413  is preferably located upward of the second hole  92 . In at least one embodiment, the radially inner end of the lower end of the insulator inclined portion  413  and the second hole  92  are placed axially over each other. This arrangement helps to easily guide the lubricating oil running on the insulator inclined portion  413  to the second hole  92 . The lubricating oil having been guided to the second hole  92  can return into the sleeve bearing  50  through the second hole  92 . Accordingly, reduction of the lubricating oil in the sleeve bearing  50  is suppressed. 
     In at least one embodiment, an oil repellent agent which repels the lubricating oil is applied to at least part of the surface of at least one of the first member  8 , the second member  9 , the insulator  41 , and the housing  51 . The type of the oil repellent agent is not particularly limited. However, in at least one embodiment, the oil repellent agent has such a characteristic that the oil repellent agent is unlikely to undergo chemical changes with the lubricating oil. In at least one embodiment, the oil repellent agent has such a characteristic that the oil repellent agent is unlikely to affect the properties such as viscosity of the lubricating oil. Applying the oil repellent agent makes the lubricating oil having leaked from inside the sleeve bearing  50  unlikely to adhere to a member other than the sleeve bearing  50 , and thus helps to efficiently return the lubricating oil into the sleeve bearing  50 . 
       FIG. 8  is a schematic view of a position to apply the oil repellent agent  300  according to at least one embodiment. The thick dashed line in  FIG. 8  indicates the position to apply the oil repellent agent  300 . In the example shown in  FIG. 8 , the oil repellent agent is applied at least part of the surfaces of all of the first member  8 , the second member  9 , the insulator  41 , and the housing  51 . In at least one embodiment, the application of the oil repellent agent to each member is carried out for each member before each member is incorporated into the motor  100 . This helps to reduce the workload to apply the oil repellent agent  300 . In addition, the oil repellent agent  300  is prevented from adhering to an undesirable portion during the application work. 
     In at least one embodiment the oil repellent agent  300  is applied to at least one of the upper face and the lower face of the first member  8 . In  FIG. 8 , the oil repellent agent  300  is applied to the upper face and the lower face of the first member  8 . Since the first member  8  is a rotary body, applying the oil repellent agent to at least one of the upper face and the lower face of the first member  8  allows the lubricating oil to be flown to the insulator inclined portion  413  by centrifugal force. Thereafter, the lubricating oil can run on the insulator inclined portion  413  to return from the second hole  92  into the sleeve bearing  50 . 
     The oil repellent agent  300  may be applied to at least one of the upper face and the lower face of the second member  9 . In  FIG. 8 , the oil repellent agent  300  is applied to both of the upper face and the lower face of the second member  9 . The oil repellent agent  300  may be applied to the inner peripheral surface of the first hole  91  or the second hole  92 . In  FIG. 8 , the oil repellent agent  300  may be applied to the inner peripheral surface of the second cylinder portion  512 . 
     In  FIG. 8 , the oil repellent agent  300  which repels the lubricating oil is applied to the surface of the insulator inclined portion  413 . Applying the oil repellent agent  300  to the insulator inclined portion  413  helps to repel the lubricating oil having scattered along with the rotation of the shaft  1  with the insulator inclined portion  413  to return the lubricating oil from the second hole  92  into the sleeve bearing  50 . 
     In at least one embodiment, the oil repellent agent  300  is not applied to the surface of the shaft  1 . If the oil repellent agent  300  were applied to the surface of the shaft  1 , maintaining the lubricating oil radially between the shaft  1  and the sleeve bearing  50  would be difficult, where the lubricating oil is required for reducing the friction. This configuration is to avoid such a situation. One of ordinary skill in the art would understand that the oil repellent agent may be applied to a portion of the shaft  1  above the sleeve bearing  50 . However, since there is a possibility that the oil repellent agent  300  adheres to an undesirable portion of the shaft  1  during the application work, the oil repellent agent  300  is not applied to the shaft  1  according to at least one embodiment. 
       FIG. 9  is a schematic sectional view of a motor  100 A of at least one embodiment. The motor  100 A includes a first member  8 A disposed above a sleeve bearing  50 A which contains a lubricating oil. The first member  8  expands radially from an outer peripheral surface of a shaft  1 A. The first member  8 A axially faces a second member  9 A which includes a second hole  92 A. 
     The first member  8 A is a member that is attached to an upper portion of the shaft  1 A and fixed to a rotor holder  2 A. In at least one embodiment, the first member  8 A is a boss portion of blades to be attached to the motor  100 A. However, the first member  8 A may be a member separate from the blades, and may be for example a coupling member, or the like, provided only for coupling the shaft  1 A and the rotor holder  2 A. In at least one embodiment, scattering of the lubricating oil along with the rotation of the shaft  1 A is suppressed with the first member  8 A. 
       FIG. 10  is a schematic sectional view of a motor  100 B of at least one embodiment. The motor  100 B includes an upper insulating portion  411 B, but does not include the insulator inclined portion  413  or the connecting portion  412  in the motor  100 . In at least one embodiment, the configuration does not including the insulator inclined portion  413 , in the motor  100 B, because a first member  8 B has a large radius. A radially outer end of the first member  8 B is located radially outward of a radially outer end of a sleeve bearing  50 B. The first member  8 B extends to near an inner peripheral surface of a housing  51 B. With such a configuration as well, the lubricating oil having scattered along with the rotation of the shaft  1 B hits the first member  8 B, is directed to the second member  9 B, and is returned into the sleeve bearing  50 B through the second hole  92 B. 
       FIG. 11  is a schematic sectional view of a motor  100 C of at least one embodiment. The motor  100 C does not include the first member  8  in the motor  100  of the above-described embodiment. In at least one embodiment, the motor  100 C includes an inclination angle of an insulator inclined portion  413 C is larger than that of the insulator inclined portion  413  of motor  100 . A large part of the insulator inclined portion  413 C is placed axially over the upper face of a sleeve bearing  50 C. A radially inner end of the insulator inclined portion  413 C is located radially inward of a radially inner end of the second hole  92 C. This helps to efficiently cause the lubricating oil having scattered along with the rotation of the shaft  1 C to hit the insulator inclined portion  413 C, be directed toward the second member  9 C, and be returned into the sleeve bearing  50 C through the second hole  92 C. 
     One of ordinary skill in the art would understand that in the configuration of motor  100 C, the second member  9 C may be omitted. In this case as well, the lubricating oil having scattered along with the rotation of the shaft  1 C hits the insulator inclined portion  413 C and is returned into the sleeve bearing  50 C. However, providing the second member  9 C helps to reduce a larger amount of the lubricating oil to vaporize from the sleeve bearing  50 C than otherwise. 
     For example, although in the above, the structure for circulating the lubricating oil is provided only on one side in the axial direction, the structure for circulating the lubricating oil may be provided axially on either side. 
     The present disclosure may be utilized in motors included in home electronics, office automation equipment, on-vehicle equipment, and the like. 
     Features of the above-described embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While embodiments of the present disclosure have been described above, one of ordinary skill in the art would understand that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.