Abstract:
When a stator and a rotor have to be separated for whatever reason after the motor provided with a locking structure has been assembled, the separation can be conducted without breaking the rotor or the motor body. The rotor includes a rotor yoke fixed to the rotor shaft and a disk positioning portion and a disk carrying portion provided at the rotor yoke. It is further provided with a hook extending toward the stator from the insertion hole opened in the rotor yoke, the hook being formed integrally with the disk positioning portion and disk carrying portion or separately therefrom. The mating catch formed at the distal end of the hook and the latching portion formed at the stator are engaged in a contactless manner and operations can be conducted so as to deform the hook elastically from the outside through the insertion hole.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a structure of a spindle motor employed, for example, for driving disk media, more specifically to a spindle motor having a locking structure that prevents a rotor from coming out of a stator.  
           [0003]    2. Description of the Prior Art  
           [0004]    Brushless motors of an outer rotor type have been used as spindle motors for driving disk media.  
           [0005]    In order to use a brushless motor as a spindle motor, a configuration is employed in which a rotor is the so-called outer rotor and a disk carrying portion is provided directly at the rotor.  
           [0006]    Such spindle motors are typically provided with a locking structure in order to prevent a rotor from coming out of a stator.  
           [0007]    Furthermore, a configuration in which a turntable produced by machining a free cutting metal such as brass or the like is integrated with a rotor obtained by press forming a sheet-like magnetic body, or a configuration in which a turntable formed by resin molding is fixed to the rotary shaft of a motor and the rotor is integrated with the turntable are employed for the disk carrying portion.  
           [0008]    Japanese Patent Application Laid-open No. 11-86427 describes an example of a configuration having a locking structure in which a rotor is integrated with a disk carrying portion. This configuration will be explained below with reference to FIG. 8.  
           [0009]    A rotor holding jig  11  made from resin and having formed therein a boss  11   a  which is to be engaged with a disk central hole is press fit and fixed to a spindle  8 , and a rotor yoke  9  produced from a galvanized steel sheet is adhesively bonded on the outer periphery of the rotor holding jig  11 . A disk surface  11   b  is formed below the boss  11   a  and a turntable  12  made from a SUS material is mounted thereupon.  
           [0010]    At the rear surface of the disk surface  11   b , a rotor locking portion  11   c  is provided concentrically with a projection  3  provided in the stator core  1 , and the rotor is prevented from coming out by engagement with the projection  3 .  
           [0011]    Other open publications disclosing such a configuration include Japanese Patent Applications Laid-open Nos. 11-110897, 10-285858, and 2002-176742.  
           [0012]    In a spindle motor having a rotor integrated with such a turntable, the rotor holding jig  11  made from resin and the spindle  8  are press fit and fixed, and the rotor locking structure is constituted by the rotor locking portion  11   c  formed integrally with the rotor holding jig  11 .  
           [0013]    In order to prevent the rotor from coming out in the axial direction, the rotor locking portion  11   c  is provided in a protruding condition, but without contact with the projection  3 . Therefore, when the rotor has to be separated from the stator, for example, in the case of a defective motor, the rotor must be pulled forcibly by taking off the protrusion.  
           [0014]    With such forcible pulling, the distal end of the locking portion  11   c  is sometimes broken or the projection  3  is broken.  
           [0015]    If the distal end of the locking portion  11   c  is broken, the rotor holding jig  11  serving as the main component of the rotor becomes unusable and the rotor itself cannot be used anymore. Furthermore, when the projection  3  is broken, the stator (or the motor body) cannot be used.  
         SUMMARY OF THE INVENTION  
         [0016]    It is an object of the present invention to provide a reusable motor such that when a stator and a rotor have to be separated for whatever reason after the motor has been assembled, the separation can be conducted without breaking the rotor or the motor body and they can be reused.  
           [0017]    In order to resolve the above-described problems, the present invention provides a spindle motor in which a disk carrying portion is provided at a rotor of a brushless motor composed of a stator and the rotor, wherein the rotor is provided with a rotor yoke supported rotatably at the stator with a rotary shaft and a disk positioning portion and a disk carrying portion provided at the rotor yoke, and is further provided with a hook extending toward the stator from the insertion hole opened in the rotor yoke, the hook being formed integrally with the disk positioning portion and disk carrying portion or separately therefrom. The mating catch formed at the distal end of the hook and the latching portion formed at the stator are not in contact but can be engaged, and operations can be conducted so as to temporarily deform the hook elastically from the outside through the insertion hole.  
           [0018]    With such a configuration, when the rotor has to be separated form the stator, the mating catch and the latching portion are disengaged by elastically temporarily deforming the hook, and the rotor is easily separated. Further, because the hook deformation is within the elastic limit, the hook is not broken and the separated rotor can be reused.  
           [0019]    Further, in accordance with the present invention, the operation of elastically deforming the hook can be facilitated by tilting the distal end side of the hook at the prescribed inclination angle toward the rotary shaft, or by providing the hook with a protrusion for this operation.  
           [0020]    In accordance with the present invention, when a rotor and a stator in a motor provided with a locking structure have to be separated, they can be separated easily. Furthermore, the separated rotor is not broken and can be reused.  
           [0021]    Moreover, a variety of hook configurations to effect separation of the rotor and the stator. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a side sectional view of the main components illustrating an embodiment of the spindle motor in accordance with the present invention.  
         [0023]    [0023]FIG. 2 is a sectional view illustrating another embodiment of the main components in accordance with the present invention.  
         [0024]    [0024]FIG. 3 is a sectional view illustrating yet another embodiment of the main components in accordance with the present invention.  
         [0025]    [0025]FIG. 4 is a view as shown by an arrow A in FIG. 3.  
         [0026]    [0026]FIG. 5 is a side sectional view of the main components illustrating an embodiment of the present invention based on another configuration of the embodiment shown in FIG. 1.  
         [0027]    [0027]FIG. 6 is a side sectional view of the main components illustrating an embodiment of the present invention based on yet another configuration.  
         [0028]    [0028]FIG. 7 is a side sectional view of the main components illustrating an embodiment of the present invention based on another configuration of the embodiment shown in FIG. 6.  
         [0029]    [0029]FIG. 8 is a side sectional view illustrating a conventional locking structure. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    The preferred embodiment of the spindle motor in accordance with the present invention will be described hereinbelow with reference to FIGS. 1 through 7.  
         [0031]    Referring to FIG. 1, a spindle motor M is composed of a stator  20  and a rotor  30 .  
         [0032]    The stator  20  comprises a plate-like stator base  21 , a tubular bearing housing  23  having a bearing  22  installed inside thereof, a core  24  fixed to this bearing housing  23 , and a coil  25  mounted on the core  24 . The structure of the stator  20  is identical to the conventional structure, with the exception of the below-described latching portion  26 , and the explanation thereof will be omitted.  
         [0033]    The rotor  30  is the so-called outer rotor in which a rotor yoke  32  that is a magnetic body is fixed to a rotary shaft  31 . The rotor yoke  32  is formed to have a cup-like shape in which a hollow cylindrical body  34  is provided on the circumference of a disk-like flat portion  33 . A magnet  35  is mounted on the entire periphery inside the body  34 .  
         [0034]    A barring portion  36  protruding upward as shown in FIG. 1 is provided in the center of the flat portion  33 . The rotary shaft  31  is fixed by press fitting, adhesively bonding, or welding by using the barring portion  36 . This barring portion  36  may also protrude downward.  
         [0035]    As for a method for fixing the rotary shaft  31  and rotor yoke  32 , they can be also fixed via a bushing made from brass or the like.  
         [0036]    A disk carrying surface is formed at the rotor yoke by using the flat portion  33 . For example, a ring-like sheet  37  made from a rubber is pasted on the outer peripheral potion of the flat portion  33  to prevent the disk from slipping.  
         [0037]    A cap  40  made from a resin and positioning the disk on the spindle motor M is mounted in the central portion of the rotor yoke  32 . The cap  40  has an almost conical shape having a taper portion  41  for guiding a mounting hole provided in the center of the disk, comprises a magnet  39  for attracting a clamp (not shown in the figures) for disk chucking, and is mounted by press fitting a cylindrical fixing portion  42  provided in the center into the barring portion  36  of the rotor yoke  32 .  
         [0038]    In addition to the above-described methods, a variety of other methods such as latching with a hook-like member or mounting with an adhesive can be considered for mounting the cap  40  on the rotor yoke.  
         [0039]    A plurality of hooks  45  are provided concentrically around the rotary shaft  31 , those hooks constituting a locking structure which is a specific constituent feature of the present application. When the cap  40  is mounted on the rotor yoke  32 , the hooks  45  are disposed on the inner side of the rotor  30  through the insertion holes  38  provided in the rotor yoke  32 .  
         [0040]    One hook may be provided, but because the cap size differs depending on, for example, the disk type, the appropriate number of hooks is determined according to this size. The hooks  45  are molded from a resin integrally with the cap  40 .  
         [0041]    A hook  45  is composed of a foot portion  47  and a mating catch  48  provided at the distal end thereof. A projection  49  is provided at the inner side of the mating catch  48 . The projection is employed for contactless engagement with the latching portion  26  provided in the vicinity of the upper end of the bearing housing  23 .  
         [0042]    The latching portion  26  is composed of a groove  27  formed along the entire periphery in the vicinity of the upper end portion of the bearing housing  23  and a taper portion  28  for smoothly engaging the mating catch  48  with the groove  27 . The mating catch  48  is engaged by the projection  49  thereof entering the groove  27  without contact with the bearing housing  23 .  
         [0043]    The latching portion  26  may be formed directly in the bearing housing  23 , as in the present embodiment, or the resin latching portion may be formed as a separate member and mounted on the bearing housing  23  or core  24 .  
         [0044]    A through hole  46  is formed in the top surface  43  of the cap  40  and the root portion of the hook  45 . This hole serves to form the projection  49  of the mating catch  48  provided at the distal end of the hook  45 .  
         [0045]    When a shape such as that of the resin cap  40  is fabricated by injection molding, the configuration of the mold used for such molding is typically such that the side of the top surface  43  serves as a cavity and the side of the mating catch  48  serves as a core. When a shape such as that of the projection  49  of the mating catch  48  is provided, a sliding mold can be also used, but it is preferred that the mold configuration be as simple as possible. There is a comparatively high degree of freedom in selecting the shape of top surface  43  of the cap  40 , and even forming a through hole in this portion poses no problem. Accordingly, a protruding pin is provided from the cavity side to the projection  49  and the mating catch  48  is formed without fabricating a sliding mold.  
         [0046]    [0046]FIG. 2 and FIG. 3 are enlarged views of a hook  50  and a hook  55  which illustrate other embodiments of the hook  45 . FIG. 4 is a view of the hook  55  shown in FIG. 3, this view being taken as shown by an arrow A.  
         [0047]    Components identical to those in FIG. 1 are assigned with same symbols and explanation thereof is omitted.  
         [0048]    Referring to FIG. 2, a foot portion  51  of the hook  50  is formed with inclination toward the latching portion  26  at the prescribed angle of a degrees with respect to the rotary shaft  31 . The through hole  46  in this case is formed so that it enlarges inwardly according to the inward inclination of the foot portion  51 , in view of the mold configuration.  
         [0049]    On the other hand, if the insertion hole  38  is formed so that the projection  49  of the mating catch  48  passes therethrough, using elasticity of the foot portion  51  makes it unnecessary to install the foot portion  51  with a large inclination.  
         [0050]    The hook  55  shown in FIG. 3 is not inclined with respect to the gap  40 , similarly to the hook  45 , but a protruding portion  56  having a taper portion  57  is provided at the rotary shaft  31  side of the hook. The protrusion degree of this protruding portion  56  is set equal to or somewhat less than that of the projection  49  and the protruding portion is formed to have a width equal to the gap between the split projections  49 , as shown in FIG. 4.  
         [0051]    With such a shape, it is unnecessary to provide a mold for forming the cap  40  with a sliding structure, similarly to other embodiments.  
         [0052]    [0052]FIG. 5 shows an example in which the hook  45  is formed on the circumference of the cap  40 , and the projection  49  of the mating catch  48  is formed outwardly.  
         [0053]    If the cap  40  is formed in the above-described manner and the latching portion  26  is formed on the core  24  of the stator  20 , it is not necessary to provide the mold with a sliding shape and to provide a through hole  46  in the cap  40 . Therefore, the mold structure can be further simplified. Moreover, the possibility of forming freely the shape of the top surface  43  of the cap  40  is advantageous in terms of strength and precision.  
         [0054]    [0054]FIG. 6 shows a configuration in which a cap and a hook are provided separately, this configuration representing yet another embodiment.  
         [0055]    A latching member  61  formed separately from the cap  60  is installed in the insertion hole  38  of the rotor yoke  32 . The latching member  61  is composed of a hook  45 , a mounting catch  64 , and a collar  62  for fixing the base portions thereof. The collar  62  has a shape allowing it to hang around the insertion hole  38 .  
         [0056]    The latching member  61  is fixed in the insertion hole  38  of the rotor yoke with the collar  62  and the mounting catch  64 .  
         [0057]    A magnetic plate  65  for clamp attraction is fixed to the top surface  43  of the cap  60 , and through holes  66 ,  67  are provided in identical locations in the top surface  43  and magnetic plate  65 .  
         [0058]    A through hole  63  is provided at the root portion of the hook  45  and the mounting catch  64 .  
         [0059]    [0059]FIG. 7 shows an example in which a plurality of latching members  61  are provided on the rotor yoke. When a plurality of latching members  61  are provided concentrically with respect to the rotary shaft  31 , if the latching members  61  are connected to each other with the collar  62 , the mounting catch  64  is unnecessary for fixing those latching members  61  integrally in the insertion hole  38 . In this case, the hook  45  can be operated from the insertion hole  38 , without providing the special through hole  63  therefor.  
         [0060]    In this case, too, the mounting location of the latching member or the mating catch  48  may be directed outwardly.  
         [0061]    In order to separate the rotor  30  from the stator  20  in the motor M of the above-described configuration, a thin screwdriver or shaft is inserted from the through hole  46  and through the insertion hole  38  and the rotor  30  is pulled away from the stator  20  by elastically deforming the hooks  45 ,  50 ,  55 , while pushing and bending them in the direction of withdrawal from the groove  27 .  
         [0062]    If the size of the through hole or insertion hole is set at about the size of the mating catch  48 , the unnecessary large bending of the hooks  45 ,  50 ,  55  can be avoided and deformation and fracture of the hooks is prevented.  
         [0063]    In the embodiment shown in FIGS. 6 and 7, a thin screwdriver or shaft is caused to move into the through hole  46  (insertion hole  38 ) via through holes  66 ,  67  provided in the magnetic plate  65  and cap  60 .  
         [0064]    The operation of elastically deforming the hooks  45 ,  50 ,  55  in the direction of withdrawal from the groove  27  makes it possible to separate easily the rotor  30  from the stator  20 . Furthermore, because unnecessary pulling is avoided, fracture of the latching portion  26  and hooks  45 ,  50 ,  55  is prevented.  
         [0065]    Here, if the foot portion  51  is inclined, as in the hook  50 , toward the rotary shaft at the prescribed angle, then the mating catch  48  can be elastically deformed and withdrawn from the groove  27  by merely introducing a screwdriver or shaft from the through hole  46 , without pressing the hook  50  in the lateral direction with respect to the rotary shaft  31 , and the operations are further facilitated.  
         [0066]    Providing a protruding portion  56 , as in the hook  55 , and bringing a driver or shaft into contact with the protruding portion  56 , while guiding it with the taper portion  57  of the protruding portion, makes it possible to withdraw the mating catch  48  from the groove  27 , in the same manner as in the case of hook  50 , and to separate the rotor  30  easily from the stator  20 .  
         [0067]    Furthermore, in the configuration of the present embodiment, the rotor yoke  32  is fixed to the rotary shaft  31  and the latching member  61  and the cap  40  having the hooks  45 ,  50 ,  55  formed therein are mounted on the rotor yoke  32 . Therefore, even if the hooks  45 ,  50 ,  55  are broken, only the cap  40  and the latching member  61  have to be replaced on the rotor yoke  32  and it is not necessary to discard the rotor  30  which is the main component constituting the motor M.  
         [0068]    Furthermore, the cap  40  composed of a resin has an almost conical shape and was used as a disk positioning jig. However, it is also possible to extend the resin part to the disk-like flat portion  33  and to form the disk carrying portion integrally.  
         [0069]    The same effect can be also obtained by providing the above-described disk carrying portion and cap  40  made from resin as separate components and integrating the disk carrying portion and the latching member.  
         [0070]    In the present embodiment explained with reference to the appended drawings, the projection  49  was formed toward the rotary shaft  31 . However, it may be also directed from the rotary shaft  31 , that is, to the outside, and the latching portion  26  provided on the bearing housing  23  may be formed on the core. In this case, the through hole  46  is formed on the outer side of the hooks  45 ,  50 ,  55 .  
         [0071]    Furthermore, in the configuration shown in FIGS. 6 and 7, the latching member  61  was positioned below the cap  60 , but it may be also positioned on the outside of the cap  60  in the flat portion of the rotor yoke  32 . With such positioning, it is not necessary to provide through holes  66 ,  67  in the cap  60  and magnetic plate  65 , the degree of freedom in selecting a shape is increased, only the latching member may be replaced when the mating catch  48  is broken, and the cap is not wasted.  
         [0072]    [0072]FIG. 1 
         [0073]    M MOTOR  
         [0074]    [0074] 20  STATOR  
         [0075]    [0075] 26  LATCHING PORTION  
         [0076]    [0076] 27  GROOVE  
         [0077]    [0077] 28  TAPER PORTION  
         [0078]    [0078] 30  ROTOR  
         [0079]    [0079] 36  BARRING PORTION  
         [0080]    [0080] 38  INSERTION HOLE  
         [0081]    [0081] 40  CAP  
         [0082]    [0082] 45  HOOK  
         [0083]    [0083] 46  THROUGH HOLE  
         [0084]    [0084] 48  MATING CATCH