Patent Publication Number: US-2010127588-A1

Title: Motor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a motor and, more particularly, to a motor that can prevent a bearing and a rotor from disengaging. 
     2. Description of the Related Art 
     Referring to  FIG. 1 , a conventional motor  8  includes a base  81  having a shaft tube  811 , a stator  82  mounted around the shaft tube  811 , a retaining ring  83  disposed in the shaft tube  811 , a bearing  84  received in the shaft tube  811 , an abutting ring  85  coupling inside the shaft tube  811  by close-fit, and a rotor  86  having a shaft  861 . The abutting ring  85  abuts against a top of the bearing  84  to avoid the bearing  84  and the retaining ring  83  disengaging from the shaft tube  811 . The shaft  861  of the rotor  86  passes through the abutting ring  85  to couple to the bearing  84  and the shaft  861  is retained by the retaining ring  83 , such that disengagement of the rotor  86  from the base  81  is avoided during rotation of the rotor  86 . 
     However, after a long-term operation of the conventional motor  8 , deformation of the shaft tube  811  is easily caused due to heat expansion and cold shrinkage as well as stress generated during operation of the motor  8 . Thus, the abutting ring  85  can not be securely fitted in the shaft tube  811  to press and restrict the bearing  84  and that results in movement of the bearing  84  inside the shaft tube  811 . Therefore, life of the conventional motor  8  is reduced. 
     For overcoming the problems of the conventional motor  8 , there are other kinds of conventional motor on the market, which can avoid movement of a bearing effectively, such as Taiwan Patent Publication No. 200814494 entitled “BEARING POSITIONING STRUCTURE FOR A MOTOR” and Taiwan Patent Publication No. 200814495 entitled “RETAINING STRUCTURE FOR MOTOR COMPONENTS”. For example, as illustrated in  FIG. 2 , a conventional motor  9  includes a base  91  having a shaft tube  911 , a stator  92  mounted around the shaft tube  911 , a retaining seat  93 , a bearing  94 , a positioning member  95  and a rotor  96 . The retaining seat  93  and the bearing  94  are received in the shaft tube  911 . The rotor  96  has a shaft  961  rotatably coupling to the bearing  94 . The shaft tube  911  of the base  91  includes a coupling section  912  that extends radially and annularly on an end edge of the shaft tube  911 . A pressing portion  951  and a hook-shaped coupling portion  952  are formed on a bottom of the positioning member  95 , with the pressing portion  951  extending axially from the bottom of the positioning member  95  and being surrounded by the coupling portion  952 . Hence, the coupling portion  952  can engage with the coupling section  912  of the shaft tube  911  for the positioning member  95  to avoid disengaging from the shaft tube  911 , and the pressing portion  951  can press against the bearing  94  to secure the bearing  94  inside the shaft tube  911 . Therefore, the positioning member  95  effectively prevent the bearing  94  from moving inside the shaft tube  911  to enhance life of the motor  9 . Nevertheless, said conventional motor  9  has several drawbacks in use as the following. 
     First, the motor  9  has a complex structure. The retaining seat  93  and the positioning member  95  are indispensable to the motor  9  in avoiding disengagement of the rotor  96  from the base  91  and pressing the bearing  94  for positioning the bearing  94  in the shaft tube  911  respectively. Plus the formation of the coupling section  912  is necessary for coupling portion  952  of the positioning member  95  to engage. Thus, the motor  9  is designed to have a plural-component structure with the retaining seat  93  and the positioning member  95  to achieve prevention of disengagement of the rotor  96  and the bearing  94 , and it resulted in the complex structure. 
     Second, inconvenience of assembling is caused. There are too many components, such as the base  91 , the stator  92 , the retaining seat  93 , the bearing  94 , the positioning member  95  and the rotor  96 , to be assembled, and that results in a complex structure for assembly. Furthermore after settling down the retaining seat  93 , the bearing  94  and the positioning member  95 , the shaft  961  should be passed through said three components, and it&#39;s difficult to make sure whether the retaining seat  93  and the shaft  961  is mounted to each other or not because the retaining seat  93  is inside the shaft tube  911  and at the bottom thereof. Thus, difficulty in assembling the motor  9  is caused. 
     Third, revolving instability is caused. A distal part of the shaft  961 , which has a predetermined length in a longitudinal direction of the shaft  961 , is below the bearing  94  and received in the retaining seat  93  for the retaining seat  93  to mount around. However, obviously, the distal part of the shaft  961  can not revolvably couple with the bearing  94 , and thus low revolving stability of the rotor  96  is caused, for a support area between the shaft  961  and the bearing  94  is reduced. 
     Hence, there is a need for an improvement over the conventional motor. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a motor that solves the problems of the conventional motor and avoids disengagement of the rotor and the bearing by a single-component design. 
     A motor according to the preferred teachings of the present invention includes a base, a stator, a bearing, a positioning member and a rotor. The base includes a shaft tube with a closed end and an open end. The stator is mounted around the shaft tube. The bearing includes a first end face, a second end face and an axial hole connecting with the first and second end faces, with the bearing being received in the shaft tube. The positioning member includes a body fixed to the open end of the shaft tube, with a bottom face of the body that faces the shaft tube forms a pressing portion. A plurality of retaining plates is formed on an inner radial periphery of the body and extends inwards radially, with a slit being formed between a pair of retaining plates adjacent to each other. Each retaining plate has a retaining end that is a free end of each retaining plate without contacting with the body. The retaining ends jointly define a through hole aligned with the axial hole of the bearing. The rotor includes a shaft passing through the through hole of the positioning member and the axial hole of the bearings. The shaft has an annular groove formed in an outer periphery thereof to form a neck of the shaft. The neck is in the through hole of the positioning member while a periphery of the through hole of the positioning member surrounds the annular groove. The retaining ends of the retaining plates are in the annular groove. Accordingly, by a single-component design of the positioning member, departures of the rotor and the bearing are both avoided, so that a simplified structure, convenience of assembling and enhanced revolving stability are provided. 
     In a most preferred form, a coupling section is formed on an end edge of the shaft tube and adjacent to the open end of the shaft tube, and a coupling portion is formed on an outer bottom edge of the body and surrounding the pressing portion, with the coupling portion engaging with the coupling section. Accordingly, the positioning member is assuredly fixed to the open end of the shaft tube securely to press the bearing effectively. 
     In a most preferred form, an outer circumference of the shaft tube forms an auxiliary engaging portion between the closed end and the open end of the shaft tube, and a bottom of the stator forms a first connecting portion engaging with the auxiliary engaging portion. Accordingly, coupling stability between the positioning member and the shaft tube is enhanced. 
     In a most preferred form, a top of the stator forms a second connecting portion engaging with an outer radial periphery of the body of the positioning member. Accordingly, the positioning member is assuredly fixed to the open end of the shaft tube securely to press the bearing effectively. 
     In a most preferred form, an annular protrusion is formed on the inner periphery of the body and above the retaining plates to define a hole for the shaft to pass through; or alternatively, an annular wall is formed on a top of the body of the positioning member and extends axially, with the annular wall being outside the shaft tube and surrounding the shaft. Accordingly, dust-proof effect is provided to prevent dust or impurities from entering the shaft tube. 
     In a most preferred form, the pressing portion abuts against the second end face of the bearing; or alternatively, a washer is disposed inside the shaft tube and on the second end face of the bearing, with the pressing portion abutting against the washer. Accordingly, the bearing is retained in the shaft tube without any movement by the direct or indirect abutting of the pressing portion. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferable embodiments of the invention, are given by way of illustration only, since various will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a cross sectional view illustrating a conventional motor; 
         FIG. 2  is a cross sectional view illustrating another conventional motor; 
         FIG. 3  is an exploded perspective view illustrating a motor in accordance with a first embodiment of the present invention; 
         FIG. 4  is a cross sectional view illustrating the motor in accordance with the first embodiment of the present invention; 
         FIG. 5  is an exploded perspective view illustrating a motor in accordance with a second embodiment of the present invention; 
         FIG. 6  is a cross sectional view illustrating the motor in accordance with the second embodiment of the present invention; 
         FIG. 7  is an exploded perspective view illustrating a motor in accordance with a third embodiment of the present invention; and 
         FIG. 8  is a cross sectional view illustrating the motor in accordance with the third embodiment of the present invention. 
     
    
    
     In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “annular”, “axial”, “radial”, “outer”, “inner”, “section”, “portion”, “end”, and similar terms are used hereinafter, it should be understood that these terms are reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A motor designated  1  of a first embodiment according to the preferred teachings of the present invention is shown in  FIGS. 3 and 4  of the drawings. According to the first embodiment form shown, the motor includes a base  10 , a stator  20 , a bearing  30 , a positioning member  40 , and a rotor  50 . 
     The base  10  can be designed as a frame of a fan, such that the motor of the present invention can be utilized for a heat-dissipating fan. In the first embodiment, the base  10  has a shaft tube  11  and two ends of the shaft tube  11  are a closed end  111  and an open end  112 . 
     The stator  20  is mounted around the shaft tube  11  of the base  10  to drive the rotor  50  to revolve. 
     The bearing  30  has a first end face  31 , a second end face  32  and an axial hole  33  connecting with the first end face  31  and the second end face  32 . And the bearing  30  is received in the shaft tube  11  of the base  10 , with the first end face  31  and the second end face  32  being adjacent to the closed end  111  and the open end  112  respectively. 
     The positioning member  40  has a body  41  that is preferably in the shape of a ring. The body  41  is fixed to the open end  112  of the shaft tube  11  of the base  10  by engagement, adhesive, welding or other methods. A bottom face of the body  41  forms a pressing portion  411  that extends axially into the shaft tube  11  to press against the bearing  30 , so that axial movement of the bearing  30  inside the shaft tube  11  is avoided. Optionally, the pressing portion  411  presses against the bearing  30  directly or indirectly. Specifically, as shown in  FIG. 4 , the pressing portion  411  directly presses against the second end face  32  of the bearing  30 , such that the bearing  30  is securely sandwiched and positioned between the positioning member  40  and the closed end  111  of the shaft tube  11 . Otherwise, the pressing portion  411  presses against a washer (not illustrated) mounted on the second end face  32  of the bearing  30 . Besides, the positioning member  40  further includes a plurality of retaining plates  42  formed on an inner radial periphery of the body  41  and extending inwards radially, with a slit  421  being formed between a pair of retaining plates  42  adjacent to each other to provide the retaining plates  42  with improved deforming ability. Each retaining plate  42  has a retaining end  422  that is a free end of the retaining plate  42  without contacting with the body  41 , with the retaining ends  422  of the retaining plates  42  jointly defining a through hole  423  aligned with the axial hole  33  of the bearing  30 . 
     The rotor  50  has a shaft  51  with one end thereof rotatably extending into the bearing  30 . An annular groove  511  is formed in an outer periphery of the shaft  51  to form a neck of the shaft  51 , with the annular groove  511  being close to the other end of the shaft  51 . In addition, the neck of the shaft  51  has an outer diameter smaller than that of two sections of the shaft  51 , with said two sections being adjacent to two end edges of the annular groove  511 . The outer diameter of the neck of the shaft  51  is smaller than a diameter of the through hole  423  of the positioning member  40  and the outer diameters of the two sections adjacent to the neck of the shaft  51  are slightly larger than the diameter of the through hole  423  of the positioning member  40 . Hence, the positioning member  40  is mounted around the shaft  51 , after the shaft  51  is forcibly inserted through the through hole  423  of the retaining member  40  to be rotatably received in the axial hole  33  of the bearing  30 . With the above-mentioned structure, the neck of the shaft  51  is in the through hole  423  of the positioning member  40  while a periphery of the through hole  423  of the positioning member  40  surrounds the annular groove  511  of the shaft  51 . Besides, the retaining plates  42  of the retaining member  40  extends into the annular groove  511  of the shaft  51 , with the retaining ends  422  of the retaining plates  42  being in the annular groove  511  to retain the shaft  51 . Therefore, by the retaining plates  42  of the retaining member  40 , departure of the rotor  50  from the base  10  is avoided during packing, loading and unloading, conveyance or operation of the motor  1 . 
     In use of the motor  1  of the first embodiment according to the preferred teachings of the present invention, the stator  20  is provided with an electric current to generate alternative magnetic fields, and thus the rotor  50  with a permanent magnet (not illustrated) is driven by the alternative magnetic fields to revolve. The rotor  50  may couple to a plurality of blades (not illustrated) on an outer periphery thereof to be jointly regarded as an impeller when the motor of the present invention is used as a heat-dissipating fan. 
     The motor  1  of the present invention is characterized in that the positioning member  40  is fixedly attached to the open end  112  of the shaft tube  11  while the pressing portion  411  of the positioning member  40  abuts against the bearing  30  to retain the bearing  30  inside the shaft tube  11 . Additionally, the retaining ends  422  of the retaining plates  42  of the positioning member  40  are in the annular groove  511  of the rotor  50  to provide a retaining effect to avoid the rotor  50  disengaging from the base  10 . Therefore, departures of the rotor  50  and the bearing  30  are both avoided by a single-component design of the positioning member  40 . 
     The followings are other embodiments according to the preferred teachings of the present invention. It is noted that the major difference between the first embodiment and said other embodiments are configuration of the positioning member and the ways to couple the positioning member to the shaft tube of the base. 
       FIGS. 5 and 6  show a motor  1   a  of a second embodiment according to the preferred teachings of the present invention. The motor  1   a  includes a base  10   a,  a stator  20 , a bearing  30 , a positioning member  40   a  and a rotor  50  wherein the stator  20 , the bearing  30  and rotor  50  are similar to those of the motor  1  of the first embodiment and descriptions thereof are therefore omitted. 
     The base  10   a  of the second embodiment according to the preferred teachings of the present invention has a shaft tube  11  with a closed end  111  and an open end  112 . The shaft tube  11  includes a coupling section  12  selected from annular flange, a plurality of blocks, a plurality of holes or others which can allow the positioning member  40   a  to engage with the coupling section  12 . Preferably, the coupling section  12  is an annular flange that extends radially on an end edge of the shaft tube  11  as shown in  FIG. 5 , with the coupling section  12  being adjacent to the open end  112  of the shaft tube  11 . Furthermore, a wear-resisting plate  13  is received in the shaft tube  11  and at the closed end  111 , so as to abut upon the shaft  51  to prevent the abrasions of the shaft  51  and the base  10   a  during rotation of the rotor  50 . 
     The positioning member  40   a  of the second embodiment according to the preferred teachings of the present invention has a body  41  with a bottom face forming a pressing portion  411  that extends axially into the shaft tube  11 . A plurality of retaining plates  42  is annularly formed on an inner radial periphery of the body  41 . In the second embodiment, the retaining plates  42  extend radially from an inner periphery of the pressing portion  411 , with the retaining plates  42  also having slits  421 , retaining ends  422  and through hole  423  similar to those in the first embodiment and descriptions of them being thus omitted. An annular protrusion  43  is formed on the inner periphery of the body  41  and above the retaining plates  42  to define a hole  431 , with a diameter of the hole  431  being slightly larger than the two sections of the shaft  51  adjacent to end edges of the annular groove  511  to minimized space between the shaft  51  and the annular protrusion  43 . Hence, the annular protrusion  43  is able to provide dust-proof effect to prevent dust or impurities from entering the shaft tube  11  due to air currents resulting from rotation of the rotor  50 , so that the rotor  50  is assured to rotate smoothly through the bearing  30  to prolong life of the motor  1   a.    
     Moreover, the positioning member  40   a  of the second embodiment according to the preferred teachings of the present invention has a coupling portion  44  formed on an outer bottom edge of the body  41  and surrounding the pressing portion  411 , with the coupling portion  44  engaging with the coupling section  12  of the base  10   a  to fix the positioning member  40   a  to the open end  112  of the shaft tube  11 . The coupling portion  44  is selected from an annular flange with a hook-shaped cross-section, a plurality of blocks or other designs, which can achieve the function of engagement between positioning member  40   a  and the coupling section  12 . As  FIGS. 5 and 6  shown, the coupling portion  44  is an annular flange with a hook-shaped cross-section and spaced from the pressing portion  411  with a gap, with the open end  112  of the shaft tube  11  being wedged into the gap. Thus, the pressing portion  411  can unhinderedly abut against the second end face  32  of the bearing  30 . 
     Therefore, the motor  1   a  of the second embodiment according to the preferred teachings of the present invention also can use the single-component design, namely the positioning member  40   a,  to achieve prevention of disengagement of the rotor  50  and the bearing  30 . Besides, the positioning member  40   a  is assuredly firmly mounted on the open end  112  of the shaft tube  11  and provides dust-proof effect as well. 
       FIGS. 7 and 8 , show a motor  1   b  of a third embodiment according to the preferred teachings of the present invention. The motor  1   b  includes a base  10   b,  a stator  20   b,  a bearing  30 , a positioning member  40   b  and a rotor  50  wherein the bearing  30  and rotor  50  are similar to those of the motor  1  of the first embodiment and descriptions thereof are therefore omitted. 
     The base  10   b  of the third embodiment according to the preferred teachings of the present invention has a shaft tube  11  with a closed end  111  and an open end  112 . Preferably, an outer circumference of the shaft tube  11  forms an auxiliary engaging portion  14 , with the auxiliary engaging portion  14  being selected from an annular flange, a plurality of blocks, a plurality of holes or others which can allow the stator  20   b  to engages with the shaft tube  11 . The auxiliary engaging portion  14  is an annular flange and between the closed end  111  and the open end  112  of the shaft tube  11 . In addition, a wear-resisting plate  13  is received in the shaft tube  11 . 
     A bottom and a top of the stator  20   b  of the third embodiment according to the preferred teachings of the present invention form a first connecting portion  21  and a second connecting portion  22  respectively. The first connecting portion  21  engages with the auxiliary engaging portion  14  of the base  10   b,  such that the stator  20   b  is securely mounted around the shaft tube  11 . Each of the first connecting portion  21  and the second connecting portion  22  is selected from an annular flange, a plurality of blocks or others, which can be engaged with. Both of the first connecting portion  21  and the second connecting portion  22  in the third embodiment are plural blocks. 
     The positioning member  40   b  has a body  41  with a bottom face forming a pressing portion  411  that extends axially into the shaft tube  11 . A plurality of retaining plates  42  is annularly formed on an inner periphery of the body  41 , with the retaining plates  42  also having slits  421 , retaining ends  422  and through hole  423  similar to those in the first embodiment and descriptions of them being thus omitted. In the third embodiment, the second connecting portion  22  of the stator  20   b  engages with an outer radial periphery of the body  41 , while the positioning member  40   b  is disposed on the open end  112  of the shaft tube of the base  10   b,  such that the positioning member  40   b  can be fixed on the open end  112  of the shaft tube  11 . An annular wall  45  is formed on a top of the body  41  of the positioning member  40   b  and extends axially, with the pressing portion  411  and the annular wall  45  being at two opposite axial end faces of the body  41 . And a washer  46  is disposed inside the shaft tube  11  and on the second end face  32  of the bearing  30 . While the positioning member  40  is fixed on the open end  112  of the shaft tube  11 , the annular wall  45  is outside the shaft tube  11  and surrounds the shaft  51 , with an end edge of the annular wall  45  is close to an inner top face of the rotor  50  to provide dust-proof effect. This avoids dusts or impurities from entering the shaft tube  11  due to air currents resulting from rotation of the rotor  50 . Hence, life of the motor  1   b  is prolonged. Besides, the pressing portion  411  indirectly abuts against the bearing  30  through the washer  46  to prevent movement of the bearing  30  inside the shaft tube  11 . 
     Therefore, the motor  1   b  of the third embodiment according to the preferred teachings of the present invention also can use the single-component design, namely the positioning member  40   b,  to prevent the rotor  50  and the bearing  30  from disengaging at the same time. And the dust-proof effect is also provided by the positioning member  40   b  that is firmly mounted on the open end  112  of the shaft tube  11 . Besides, reliability of combination of the stator  20   b  and the base  10   b  is enhanced. 
     As has been discussed above, the motor  1 ,  1   a,    1   b  is indeed able to overcome problems of the conventional motors and has many advantages as the following. 
     First, a simplified structure is provided. In contrast to the conventional motor  9  whose rotor and bearing are positioned by the retaining seat  93  and the positioning member  95  respectively, disengagement of both of the rotor  50  and the bearing  30  of the motor  1 ,  1   a,    1   b  of the present invention is avoided merely by the single-component design, namely the positioning member  40 ,  40   a,    40   b.  Accordingly, an amount of components of the motor  1 ,  1   a,    1   b  of the present invention is decreased to reduce structural complexity. 
     Second, convenience of assembling is provided. Owing to the simplified structure of the motor  1 ,  1   a,    1   b,  after the stator  20 ,  20   b  and the bearing  30  are mounted to the shaft tube  11  of the base  10 ,  10   a,    10   b,  a quick assembling merely including fixing the positioning member  40 ,  40   a,    40   b  to the shaft tube  11  and coupling the rotor  50  to the base  10 ,  10   a,    10   b  is provided. The more important is that without the retaining seat  93  of the conventional motor  9  leads to fewer steps in assembling and reliable combination of related components. 
     Third, revolving stability is enhanced. By the positioning member  40 ,  40   a,    40   b,  preventing departure of the rotor  50  from the shaft tube  11  can be achieved, so that a distal part of the shaft  51 , which has a predetermined length in a longitudinal direction of the shaft  51  and is below the bearing  30 , for being received in a retaining seat is not necessary. Accordingly, the motor  1 ,  1   a,    1   b  of the present invention without a need for the predetermined length can increase the support area between the bearing  30  and the shaft  51  to improve revolving stability of the rotor  50  effectively. 
     Although the invention has been described in detail with reference to its presently preferable embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.