Abstract:
There is provided a bearing assembly including: a sleeve supporting a shaft and including a circulation hole through which oil is circulated; a thrust plate coupled to the shaft and generating dynamic pressure in the oil; and a base cover coupled to the sleeve to thereby close a lower portion of the sleeve, wherein the oil passes through the circulation hole and is then supplemented between the thrust plate and the base cover in order to suppress bubblegeneration due to leakage of the oil filled between the thrust plate and the base cover at the time of rotation of the shaft.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2011-0095652 filed on Sep. 22, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a bearing assembly and a motor including the same, and more particularly, to a motor capable of being used in a hard disk drive (HDD) rotating a recording disk. 
         [0004]    2. Description of the Related Art 
         [0005]    A hard disk drive (HDD), an information storage device, reads data stored on a disk or writes data to the disk using a read/write head. 
         [0006]    The hard disk drive requires a disk driving device capable of driving the disk. As the disk driving device, a spindle motor is used. 
         [0007]    In the spindle motor, a fluid dynamic bearing assembly is used. A shaft, a rotating member of the fluid dynamic bearing assembly, and a sleeve, a fixed members thereof, include oil interposed therebetween, such that the shaft is supported by fluid pressure generated in the oil. 
         [0008]    The spindle motor as described above requires a predetermined floating force for rotation of the rotating member. In this case, in order to prevent the rotating member from being excessively floated due to the generation of force larger than floating force required for the rotation of the rotating member, a pulling plate is coupled to an area corresponding to a magnet to thereby suppress floating force. 
         [0009]    However, in this case, there is a limitation in providing a constant pulling force based on a shaft due to process characteristics thereof. Therefore, a phenomenon in which the rotating member rotates while being eccentric from the fixed member has not been completely solved. 
         [0010]    In addition, the pulling plate provided in order to prevent the excessive floating of the rotating member may be separated from a base due to external impact, or the like, thereby causing a fatal problem in motor performance. 
         [0011]    Further, the coupling of the pulling plate allows a thickness of the base to be reduced, thereby having an influence on the strength of the base. 
         [0012]    Therefore, in the spindle motor used in a recording disk driving device, research into a new shaft system suppressing excessive floating of a rotating member to thereby improve performance and a lifespan of the spindle motor has been urgently demanded. 
       SUMMARY OF THE INVENTION 
       [0013]    An aspect of the present invention provides a bearing assembly having a new shaft system structure in which negative pressure between a thrust plate and a base cover is prevented to suppress bubble generation, and a rotating member rotates while descending, at the time of rotation of the rotating member, and a motor including the same. 
         [0014]    According to an aspect of the present invention, there is provided a bearing assembly including: a sleeve supporting a shaft and including a circulation hole through which oil is circulated; a thrust plate coupled to the shaft and generating dynamic pressure in the oil; and a base cover coupled to the sleeve to thereby close a lower portion of the sleeve, wherein the oil passes through the circulation hole and is then supplemented between the thrust plate and the base cover in order to suppress bubble generation due to leakage of the oil filled between the thrust plate and the base cover at the time of rotation of the shaft. 
         [0015]    The dynamic pressure may be generated by a thrust dynamic pressure part formed in at least one of an upper surface of the thrust plate and the sleeve facing the upper surface of the thrust plate. 
         [0016]    The shaft may rotate while descending by force directed downwardly in an axial direction by dynamic pressure at the time of rotation thereof. 
         [0017]    The thrust plate and the sleeve may be maintained in a state in which they contact each other while the motor is stopped. 
         [0018]    The circulation hole may allow upper and lower surfaces of the sleeve to be in communication with each other and be formed at an outer side of the thrust plate in a radial direction. 
         [0019]    The shaft and the thrust plate may be formed integrally with each other. 
         [0020]    According to another aspect of the present invention, there is provided a motor including: the bearing assembly as described above; a hub rotating together with the shaft and having a magnet coupled thereto; and a based coupled to the sleeve and including a core having a coil wound therearound, the coil generating rotational driving force. 
         [0021]    The thrust plate may be maintained in a state in which it contacts the sleeve by magnetic attractive force due to a difference in position between the magnetic center of the magnet and the center of the core while the motor is stopped. 
         [0022]    An oil sealing part allowing an oil interface to be formed may be provided between the upper surface of the sleeve and the hub. 
         [0023]    A pumping part pumping the oil between the shaft and the sleeve may be provided in at least one of the upper surface of the sleeve and one surface of the hub facing the upper surface of the sleeve. 
         [0024]    An interval between the upper surface of the sleeve and the hub may increase in an outer diameter direction. 
         [0025]    The upper surface of the sleeve may be inclined downwardly in an outer diameter direction. 
         [0026]    One surface of the hub facing the upper surface of the sleeve maybe inclined upwardly in an outer diameter direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0028]      FIG. 1  is a schematic cross-sectional view showing a motor including a bearing assembly according to an embodiment of the present invention; 
           [0029]      FIG. 2  is a schematic cut-away perspective view showing a sleeve provided in the bearing assembly according to the embodiment of the present invention; 
           [0030]      FIG. 3  is a schematic cut-away perspective view showing a hub provided in the bearing assembly according to the embodiment of the present invention; 
           [0031]      FIG. 4  is a schematic cross-sectional view showing a stop state of the motor according to the embodiment of the present invention; and 
           [0032]      FIGS. 5A and 5B  are schematic enlarged cross-sectional views of part A of  FIG. 4 , showing a stop state and an initial rotation state of the motor according to the embodiment of the present invention, respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, it should be noted that the spirit of the present invention is not limited to the embodiments set forth herein and those skilled in the art and understanding the present invention can easily accomplish retrogressive inventions or other embodiments included in the spirit of the present invention by the addition, modification, and removal of components within the same spirit, but those are construed as being included in the spirit of the present invention. 
         [0034]    Further, like reference numerals will be used to designate like components having similar functions throughout the drawings within the scope of the present invention. 
         [0035]      FIG. 1  is a schematic cross-sectional view showing a motor including a bearing assembly according to an embodiment of the present invention;  FIG. 2  is a schematic cut-away perspective view showing a sleeve provided in the bearing assembly according to the embodiment of the present invention; and  FIG. 3  is a schematic cut-away perspective view showing a hub provided in the bearing assembly according to the embodiment of the present invention. 
         [0036]    Referring to  FIGS. 1 through 3 , a motor  10  according to an embodiment of the present invention may include a bearing assembly  100 , a hub  200  having a magnet  210  coupled thereto, and a base  300  including a core  320  having a coil  310  wound therearound. 
         [0037]    Terms with respect to directions will be first defined. As viewed in  FIG. 1 , an axial direction refers to a vertical direction based on the shaft  110 , and an outer diameter or inner diameter direction refers to a direction towards an outer edge of the hub  210  based on the shaft  110  or a direction towards the center of the shaft  110  based on the outer edge of the hub  210 . 
         [0038]    The bearing assembly  100  may include the shaft  110 , a sleeve  120  including a circulation hole  125 , a thrust plate  130 , and a base cover  140 . 
         [0039]    The sleeve  120  may be a component supporting the shaft  110 , a component of the rotating member. The sleeve  120  may support the shaft  110  so that an upper end of the shaft  110  protrudes upwardly in an axial direction and may be formed by forging Cu or Al or sintering a Cu-Fe based alloy powder or a SUS based power. 
         [0040]    The sleeve  120  may include a shaft hole having the shaft  110  inserted thereinto so as to have a micro clearance therebetween, wherein the micro clearance may be filled with oil O to thereby stably support the shaft  110  by radial dynamic pressure in the oil O. 
         [0041]    Here, the radial dynamic pressure by the oil O may be generated by upper and lower fluid dynamic parts  122  and  124  formed as a groove in an inner peripheral surface of the sleeve  120 . The upper and lower fluid dynamic parts  122  and  124  may have anyone of a herringbone shape, a spiral shape, and a screw shape. 
         [0042]    However, the upper and lower fluid dynamic parts  122  and  124  are not limited to being formed in the inner peripheral surface of the sleeve  120  as described above but may also be formed in an outer peripheral surface of the shaft  110 , the rotating member. In addition, the number of upper and lower fluid dynamic parts  124  and  122  is also not limited. 
         [0043]    In addition, the sleeve  120  may include a thrust dynamic pressure part  135  formed in a lower surface thereof, wherein the thrust dynamic pressure part  135  pumps the oil O filled in a clearance between the sleeve  120  and a thrust plate  130  to be described below in an inner diameter direction to thereby generate thrust dynamic pressure downwardly in the axial direction in the thrust plate  130 , the rotating member. 
         [0044]    That is, when power is applied to the coil  310 , the thrust plate  130  may pump the oil O filled between the thrust plate  130  and the sleeve  120  in the inner diameter direction by the thrust dynamic pressure part  135  to thereby allow the rotating member including the shaft  110  and the thrust plate  130  to rotate while descending. 
         [0045]    Here, the thrust dynamic pressure part  135  may have one of a herringbone shape, a spiral shape, a screw shape, similar to the upper and lower fluid dynamic parts  122  and  124 . 
         [0046]    However, the thrust dynamic pressure  135  is not limited to being formed in the lower surface of the sleeve  120  but may also be formed in an upper surface of the thrust plate  130 , the rotating member. 
         [0047]    The thrust plate  130  may be coupled to the shaft  110  by bonding using an adhesive, welding, press-fitting, or the like, and may also be formed integrally with the shaft  110  rather than a separate member from the shaft  110 . 
         [0048]    Here, the thrust plate  130  may be maintained in a state in which it contacts the lower surface of the sleeve  120  while the motor is stopped (See  FIG. 4 ), and force allowing the thrust plate  130  to be maintained in a state in which it contacts the lower surface of the sleeve  120  may be generated by a difference in height between the center C 1  (See  FIG. 4 ) of the core  320  and the magnetic center C 2  (See  FIG. 4 ) of the magnet  210  coupled to the hub  200 . 
         [0049]    A detailed description thereof will be described below with reference to  FIG. 4 . 
         [0050]    The sleeve  120  may include the base cover  140  coupled thereto at a lower portion thereof in the axial direction, having a clearance therebetween, wherein the clearance receives the oil O therein. 
         [0051]    The base cover  140  may receive the oil O in the clearance between the base cover  140  and the sleeve  120  to thereby serve as a bearing supporting a lower surface of the shaft  110 . 
         [0052]    In addition, the oil O may be continuously filled in a clearance between the shaft  110  and the sleeve  120 , in a clearance between a hub  200  to be described below and the sleeve  120 , and in clearances between the base cover  140  and the shaft  110  and between the base cover  140  and the thrust plate  130  to thereby form the entire full-fill structure. 
         [0053]    Further, an interval between an upper surface of the sleeve  120  and the hub  200  facing the upper surface of the sleeve  120  may increase in the outer diameter direction. 
         [0054]    More specifically, as shown in  FIG. 1 , the upper surface of the sleeve  120  may be inclined downwardly in the outer diameter direction. 
         [0055]    In addition, although not shown, one surface of the hub  200  facing the upper surface of the sleeve  120  may be inclined upwardly in the outer diameter direction or both of the upper surface of the sleeve  120  and one surface of the hub  200  may be inclined. 
         [0056]    This is to prevent leakage of the oil O using a capillary phenomenon of the oil O filled in the clearance between the upper surface of the sleeve  120  and the hub  200  facing the upper surface of the sleeve  120  to thereby significantly increase the sealing capability of the oil O simultaneously with securing a storage space of the oil O. 
         [0057]    An interface of the oil O may be formed between the upper surface of the sleeve  120  and one surface of the hub  200  facing the supper surface of the sleeve  120 . In addition, an oil sealing part  400  maintaining the interface of the oil O in a normal state may be provided therebetween. 
         [0058]    The oil sealing part  400  may be formed by the upper surface of the sleeve  120  and one surface of the hub  200 . More specifically, the oil sealing part  400  refers an interval between the upper surface of the sleeve  120  and one surface of the hub  200 . 
         [0059]    Here, an interval between the base cover  140  and the thrust plate  130  may be larger than that between the upper surface of the sleeve  120  and the hub  200 . 
         [0060]    Therefore, when the shaft  110  and the hub  200  moves downwardly in the axial direction due to external impact, or the like, the upper surface of the sleeve  120  and the hub  200  first contact each other to thereby prevent the thrust plate  130  from contacting the base cover  140 . 
         [0061]    Therefore, since the base cover  140  does not contact the thrust plate  130  in spite of the external impact, or the like, the base cover  140  needs not to have a thickness required to prevent damage due to the contact. 
         [0062]    That is, the base cover  140  may be coupled to the sleeve  120  in a state in which it has a thin thickness to thereby seal the lower portion of the sleeve  120 . 
         [0063]    Therefore, in miniaturization and thinness of the motor  10  according to the embodiment of the present invention, since the thickness of the base cover  140  may be relatively reduced, the entire height of the sleeve  120  may be maintained so as to be equal to that of the sleeve according to the related art or be increased as compared to that of the sleeve according to the related art. 
         [0064]    Accordingly, since a distance between points at bent portions in the upper and lower fluid dynamic parts  122  and  124 , that is, a bearing span length may be increased, the entire rigidity of the bearing may be improved. 
         [0065]    Here, the sleeve  120  may include the circulation hole  125  allowing the upper and lower surfaces thereof to be in communication with each other, wherein the circulation hole  125  may allow internal pressure of the motor  10  according to the embodiment of the present invention to be maintained in an equilibrium state. 
         [0066]    In addition, the oil O between the thrust plate  130  and the base cover  140  may be supplemented by the circulation hole  125  when power is applied to the coil  310  and the rotating member including the shaft  110  thus starts to rotate. 
         [0067]    In other words, when the rotating member starts to rotate, the oil O filled between the thrust plate  130  and the sleeve  120  may be pumped in the inner diameter direction by the thrust dynamic pressure part  135  formed in at least one of the lower surface of the sleeve  120  and the upper surface of the thrust plate  130 . 
         [0068]    Since this pumping force F 1  (See  FIG. 5 ) is in inverse proportion to an interval between the lower surface of the sleeve  120  and the upper surface of the thrust plate  130 , relatively strongest pumping force F 1  may be generated at the time of initial driving of the motor  10  according to the embodiment of the present invention. 
         [0069]    Therefore, at the time of the initial driving of the motor  10  according to the embodiment of the present invention, the oil O filled between the thrust plate  130  and the base cover  140  may be leaked to the outside by the strong pumping force F 1  in the inner diameter direction. 
         [0070]    Therefore, negative pressure may be generated between the thrust plate  130  and the base cover  140 . As a result, bubbles may be generated due to the generation of the negative pressure to thereby cause a defect in smooth rotation of the rotating member including the shaft  110  and the thrust plate  130 . 
         [0071]    However, since the motor  10  according to the embodiment of the present invention may supplement the oil O between the thrust plate  130  and the base cover  140  by the circulation hole  135  formed at an outer side of the thrust plate  130  in a radial direction, the generation of the bubbles due to the negative pressure at the time of the initial driving of the motor  10  may be prevented in advance. 
         [0072]    The hub  200 , which is a rotating member coupled to an upper portion of the shaft  110  to thereby rotate together with the shaft  110 , may include an annular ring shaped magnet  210  provided on an inner peripheral surface thereof, wherein the annular ring shaped magnet  210  faces the core  320  having the coil  310  wound therearound, having a predetermined interval therebetween. 
         [0073]    In addition, the hub  200  may include a pumping part  205  formed in an inner surface thereof, that is, one surface thereof facing the upper surface of the sleeve  120 . 
         [0074]    The pumping part  205 , a component for preventing the leakage of the oil O filled between the upper surface of the sleeve  120  and the hub  200 , may pump the oil O between the shaft  110  and the sleeve  120  at the time of the rotation of the motor  10  according to the embodiment of the present invention. 
         [0075]    Therefore, the leakage of the oil O due to the external impact, or the like, at the time of the rotation of the motor  10  according to the embodiment of the present invention may be prevented, such that an amount of the oil O may be appropriately maintained. As a result, the dynamic pressure in the oil O is maintained, whereby rigidity of the bearing may be improved. 
         [0076]    Here, the pumping part  205  may have a groove having a spiral shape as shown in  FIG. 3  but is not limited thereto. That is, the pumping part  205  may also have a herringbone shape or a screw shape. 
         [0077]    The base  300 , a component coupled to the sleeve  120  to thereby support the rotation of the rotating member, may include the core  320  coupled thereto, wherein the core  320  includes the coil  310  wound therearound. 
         [0078]    In other words, the base  300  may be the fixed member including an insertion hole formed therein so that the sleeve  120  supporting the shaft  110 , a shaft system of the motor  10  according to the embodiment of the present invention, is coupled thereto, and include the core  320  coupled thereto, wherein the core  320  includes the coil  310  wound theraround and the coil  310  generates electromagnetic force having a predetermined magnitude at the time of application of power. 
         [0079]    Therefore, when the power is applied to the coil  310 , rotational driving force may be generated by electromagnetic interaction between the coil  310  and the magnet  210 . 
         [0080]    Here, the base  300  maybe coupled to the sleeve  120  and the core  320  by any one bonding method among an adhesive, a welding method, and a press-fitting method. 
         [0081]      FIG. 4  is a schematic cross-sectional view showing a stop state of the motor according to the embodiment of the present invention. 
         [0082]    Referring to  FIG. 4 , while the motor  10  according to the embodiment of the present invention is stopped, the upper surface of the thrust plate  130 , which is the rotating member, and the lower surface of the sleeve  120 , which is fixed member, may be maintained in a state in which they contact each other. 
         [0083]    Here, the force allowing the thrust plate  130  and the sleeve  120  to be maintained in a state in which they contact each other may be generated by a difference in height between the center C 1  of the core  320  coupled to the base  300  and the magnetic center C 2  of the magnet  210  coupled to the hub  200 . 
         [0084]    That is, the center C 2  of the magnet  210  may be disposed at a position lower than that of the center C 1  of the core  320 , such that force F 2  directed upwardly in the axial direction may always be generated at the time of the driving or the stop of the motor  10  according to the embodiment of the present invention. The force F 2  may be larger than the weight of the rotating member. 
         [0085]    Here, the weight of the rotating member may be a concept including all of rotating components such as the shaft  110 , the thrust plate  130 , the hub  200 , a disk (not shown), a clamp (not shown) for fixing the disk (not shown), and the like, and a magnitude of magnetic attractive force between the core  320  and the magnet  210  may be in proportion to a distance between the center C 1  of the core  320  and the center C 2  of the magnet  210 . 
         [0086]    Therefore, at the time of the stop of the motor  10  according to the embodiment of the present invention, the upper surface of the thrust plate  130  and the lower surface of the sleeve  120  are maintained in a state in which they contact each other, such that a clearance between the upper surface of the sleeve  120  and the lower surface of the hub  200  is larger than a clearance therebetween at the time of the rotation the motor  10 . 
         [0087]    In addition, the magnetic attractive force due to the difference in height between the center C 2  of the magnet  210  and the center C 1  of the core  320  may continuously act even in the case in which the motor  10  according to the embodiment of the present invention rotates, and the force F 2  of the hub  200  directed upwardly in the axial direction due to the magnetic attractive force may prevent the rotating member from excessively descending. 
         [0088]    In the motor included in the hard disk drive, the rotating member generally rotates while being floated upwardly in the axial direction. In this case, in order to prevent the excessive floating of the rotating member, a pulling plate, which is a separate member, is coupled to the base. 
         [0089]    This pulling plate is formed as a separate member, thereby causing an increase in cost of the motor. In addition, in the case in which the pulling plate is coupled to the base, a coupling part needs to be formed in the base, thereby having a negative influence on rigidity of the base. 
         [0090]    However, the motor  10  according to the embodiment of the present invention has a structure in which the rotating member including the shaft  110  rotates while descending rather than being floated, and does not require a separate member such as the pulling plate for preventing the rotating member from rotating while excessively descending. 
         [0091]    That is, the excessive descent problem of the rotating member is solved only by the positions of the center C 1  of the core  320  and the magnetic center C 2  of the magnet  210 , whereby an excellent effect may be generated in view of a manufacturing cost and the rigidity of the base  300 . 
         [0092]      FIGS. 5A and 5B  are schematic enlarged cross-sectional views of part A of  FIG. 4 , showing a stop state and an initial rotation state of the motor according to the embodiment of the present invention, respectively. 
         [0093]    Referring to  FIG. 5A , when the motor  10  according to the embodiment of the present invention stops, the magnetic center C 2  of the magnet  210  is disposed at a position lower than that of the center C 1  of the core  320  in the axial direction, such that the upper surface of the thrust plate  130  and the lower surface of the sleeve  120  are maintained in a state in which they contact each other by the magnetic attractive force acting between the magnet  210  and the core  320 , as described above with reference to  FIG. 4 . 
         [0094]    In addition, a clearance between the upper surface of the sleeve  120  and the lower surface of the hub  200  is larger than a clearance therebetween at the time of the rotation the motor. 
         [0095]    Referring to  FIG. 5B , in the motor  10  according to the embodiment of the present invention, when power is applied from the outside to the coil  310  in order to rotate the rotating member including the shaft  110  and the thrust plate  130 , the hub  200  rotates by electromagnetic interaction between the coil  310  and the magnet  210 , such that the shaft  110  and the thrust plate  130  that are coupled to the hub  200  also rotate. 
         [0096]    Here, a principle that the rotating member of the motor  10  according to the embodiment of the present invention rotates while descending will be described in detail. The force directed downwardly in the axial direction is applied to the thrust plate  130  while the radial dynamic pressure is applied to the shaft  110  by the upper and lower fluid dynamic parts  122  and  124  formed in at least one of the shaft  110  and the sleeve  120 . 
         [0097]    In addition, the thrust dynamic pressure part  135  generates the pumping force F 1  in the inner diameter direction through the oil O filled between the thrust plate  130  and the sleeve  120 , such that the thrust dynamic pressure directed downwardly in the axial direction is generated in the thrust plate  130 . 
         [0098]    Therefore, the thrust plate  130  rotates in a state in which the upper surface thereof is spaced apart from the lower surface of the sleeve  120 . As a result, the rotating member may rotate while descending. 
         [0099]    When the rotating member rotates, the upper plate of the thrust plate  130  and the lower surface of the sleeve  120  is released from a state in which they contact each other to thereby form a clearance, and the oil O filled in the clearance may be pumped in the inner diameter direction by the thrust dynamic pressure part  135 , as described above. 
         [0100]    The strongest pumping force F 1  is generated at the time of initial driving of the motor  10  according to the embodiment of the present invention. The reason is that the pumping force F 1  is in reverse proportion to the interval between the lower surface of the sleeve  120  and the upper surface of the thrust plate  130 . 
         [0101]    Therefore, at the time of the initial driving of the motor  10  according to the embodiment of the present invention, the oil O filled between the thrust plate  130  and the base cover  140  may be leaked Y to the clearance between the shaft  110  and the sleeve  120  by the strong pumping force F 1  in the inner diameter direction. 
         [0102]    Due to the strong pumping force F 1  as described above, the negative pressure is generated between the thrust plate  130  and the base cover  140 , such that the bubbles may be generated to thereby cause a problem in smooth rotation of the rotating member including the thrust plate  130 . 
         [0103]    However, since the motor  10  according to the embodiment of the present invention may supplement X the oil O between the thrust plate  130  and the base cover  140  by the circulation hole  125  formed at the outer side of the thrust plate  130  in the radial direction at the time of the initial rotation of the rotating member, the generation of the negative pressure at the time of the initial driving of the motor  10  may be prevented in advance. 
         [0104]    Therefore, the motor  10  according to the embodiment of the present invention may stably rotate without generation of the bubbles due to the negative pressure at the time of the initial driving thereof. 
         [0105]    Thereafter, the rotating member including the shaft  110  and the thrust plate  130  rotates in a state in which it is maintained at a stable descending height. The excessive descent problem of the rotating member may be solved by the position relationship between the center C 1  of the core  320  and the center C 2  of the magnet  210 , that is, a structure in which the center C 2  of the magnet  210  is disposed at a position lower than that of the center C 1  of the core  320  as described above. 
         [0106]    In addition, since the center C 2  of the magnet  210  is disposed at the position lower than that of the center C 1  of the core  320 , the force F 2  directed upwardly in the axial direction acts on the entire magnet  210 , whereby the fixed member including the base  300  may more stably support the rotating member. 
         [0107]    Therefore, a phenomenon in which the rotating member rotates while being eccentric from the center of the shaft is prevented, whereby the motor  10  may be stably driven. 
         [0108]    Through the above-mentioned embodiments, the bearing assembly  100  and the motor  10  including the same according to the present invention prevents the negative pressure between the thrust plate  130  and the base cover  140  by allowing the oil O to be introduced through the circulation hole  125  at the time of the rotation of the rotating member, whereby the generation of the bubbles may be suppressed. 
         [0109]    As set forth above, in a bearing assembly and a motor including the same according to embodiments of the present invention, a phenomenon in which the rotating member rotates while excessively descending maybe prevented without using a separate member and a phenomenon in which the rotating member rotates while being eccentric from the center of the shaft may be prevented. 
         [0110]    Further, the rigidity of the bearing may be improved due to an increase in bearing span length, whereby rotational characteristics may be significantly increased. 
         [0111]    Furthermore, the negative pressure between the thrust plate and the base cover at the time of the rotation of the rotating member may be prevented to suppress the generation of the bubbles, whereby performance and a lifespan of the motor may be significantly incrased. 
         [0112]    While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.