Abstract:
A stator includes a magnetically conductive tube with a pole plate at one end. The edge of the pole plate functions as a magnetic pole. The other end of the magnetically conductive tube is combined with another pole plate. A coil is wound between the two pole plates. The edges of both pole plates extend in opposite directions to form a larger magnet pole area.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a brushless DC motor to the structure of the stator of a brushless DC motor, the stator including a magnetic conductive tube and a pole plate. 
     2. Description of the Related Art 
     Referring to FIG. 1, a conventional brushless DC motor and stator comprises a metal tube  91  with outer surface surrounded by a coil  92 , an upper pole plate  93 , a lower pole plate  94  and a circuit board  95 . The upper plate  93  and the lower plate  94  are formed by a plurality of stacked silicon steel plates so as to increase the area adjacent to the permanent magnet of the rotor. Because it consists of a plurality of silicon steel plates the conventional motor and stator are complex, the cost of manufacture is high, and much more of the material. 
     Furthermore, one end of the metal tube  91  has an annular flange  911  which is larger than the diameter of the tube. When the other end of metal tube 91  being fixed, the annular flange  911  limits the coil  92 , the upper plate  93 , the lower plate  94  and the circuit board  95 , and thus the thickness of annular flange  911  increases the thickness of the stator. In order to decrease the thickness of the stator, the annular flange  911  may be removed for the best design. 
     Furthermore, U.S. Pat. No. 4,891,567, issued on Jan. 2, 1990 to Fujitani et al., discloses a pole plate having a pole which is bent in a right angle to the pole plate. The poles are bent toward each other, so that the poles cover the outer peripheral space of the coil seat. Thus, the pole plates are pressed and combined on the stator, after coils have been wounded on the coil seat of the stator. However, the poles of the stator are arranged to face each other because the coils must first be wounded on the coil seat of the stator, and then the pole plates pressed on the bobbin to form the stator. The pressing process of pole plates into a bobbin with a wound has the disadvantage that the coil wire may be cut or cut broken, the bobbin pressed, and the enameled layer of wires damaged. Wires of the coil suffer from starting current pulses in the long term resulting in the degrading of the coil assembly and resulting in deterioration of rotation of the motor and shortening motor life. 
     SUMMARY OF THE INVENTION 
     The primary object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube, which has a pole plate on one end of the tube so as to reduce the thickness of the stator. 
     The secondary object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube, which has a pole plate on one end of the tube, and another pole plate sleeved on the other end of the tube. At least one of the two pole plates has poles which extend in opposite directions to the poles of the other pole plate to form a larger conductive area of the pole plate so as to increase the torque of motor, and to permit freedom of design in accordance with the requirements of the motor without the limitation of space. 
     The third object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube, which has a pole plate on one end of the tube, and another pole plate sleeved on the other end of the tube. At least one of the two pole plates has poles which extend in an opposite direction to those of the other pole plate to form a larger conductive area of the pole plate so as to reduce the thickness of pole plate, manufacture processes and the material cost of the pole plate. 
     The fourth object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube whose outer surface may wind a coil or support a bobbin for a coil to simplify production processes and reduce the cost of manufacture. 
     The fifth object of this invention is to provide a stator of a brushless DC motor which has a thinner thickness that uses lesser material and reduces the processes of manufacture, in order to reduce the material and the manufacturing cost. 
     The sixth object of this invention is to provide a stator with a heat dissipating device which has a thinner thickness that uses lesser material and reduces the processes of manufacture, in order to reduce the material and the manufacturing cost. 
     In accordance with the present invention, a brushless DC motor comprises a magnetic conductive tube, which has a pole plate on one end of the tube and wound coils on the outer surface of the tube, and another pole plate is sleeved on the other end of the tube. The edge of both pole plates have poles extending in opposite directions to form a larger pole edge area to increase magnetic inductive area. 
    
    
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described in detail with reference to the accompanying drawings wherein; 
     FIG. 1 is a perspective exploded view of a conventional brushless DC motor; 
     FIG. 2 is an exploded perspective view of a brushless DC motor in accordance with the first embodiment of the present invention; 
     FIG. 3 is a top view of the brushless DC motor in accordance with the first embodiment of the present invention; 
     FIG. 4 is a sectional view, along line  4 — 4 , of the brushless DC motor in accordance with a first embodiment of the present invention; 
     FIG. 5 is an exploded perspective view of a brushless DC motor in accordance with the second embodiment of the present invention; 
     FIG. 6 is a sectional view of the brushless DC motor in accordance with the second embodiment of the present invention; 
     FIG. 7 is an exploded perspective view of a brushless DC motor in accordance with a third embodiment of the present invention; 
     FIG. 8 is an exploded perspective view of a brushless DC motor in accordance with a third embodiment of the present invention; 
     FIG. 9 is an exploded perspective view of a brushless DC motor in accordance with a third embodiment of the present invention; 
     FIG. 10 is an exploded perspective view of a brushless DC motor in accordance with a fourth embodiment of the present invention; 
     FIG. 11 is a sectional view of the brushless DC motor in accordance with the fourth embodiment of the present invention; 
     FIG. 12 is an exploded perspective view of a brushless DC motor in accordance with a fifth embodiment of the present invention; 
     FIG. 13 is a sectional view of the brushless DC motor in accordance with the fifth embodiment of the present invention; 
     FIG. 14 is a sectional view of the brushless DC motor in accordance with the fifth embodiment of the present invention; 
     FIG. 15 is an exploded perspective view of a brushless DC motor in accordance with the sixth embodiment of the present invention; 
     FIG. 16 is a sectional view of the brushless DC motor in accordance with the sixth embodiment of the present invention; 
     FIG. 17 is an exploded perspective view of a brushless DC motor in accordance with the seventh embodiment of the present invention; 
     FIG. 18 is a sectional view of the brushless DC motor in accordance with the seventh embodiment of the present invention; 
     FIG. 19 is an exploded perspective view of a brushless DC motor in accordance with the eighth embodiment of the present invention; 
     FIG. 20 is a sectional view of the brushless DC motor in accordance with the eighth embodiment of the present invention; 
     FIG. 21 is an exploded perspective view of a brushless DC motor in accordance with the ninth embodiment of the present invention; 
     FIG. 22 is a sectional view of the brushless DC motor in accordance with the ninth embodiment of the present invention; 
     FIG. 23 is an exploded perspective view of a brushless DC motor in accordance with the tenth embodiment of the present invention; 
     FIG. 24 is a sectional view of the brushless DC motor in accordance with the tenth embodiment of the present invention; 
     FIG. 25 is an exploded perspective view of the brushless DC motor in accordance with the second embodiment of the present invention; 
     FIG. 26 is a sectional view of the brushless DC motor in accordance with the second embodiment of the present invention; 
     FIG. 27 is an exploded perspective view of the brushless DC motor in accordance with the second embodiment of the present invention with fixing member; 
     FIG. 28 is an exploded perspective view of the brushless DC motor in accordance with the second embodiment of the present invention with case 
     FIG. 29 is an exploded perspective view of the brushless DC motor in accordance with the second embodiment of the present invention with cooler device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 2, a brushless DC motor in accordance with the first embodiment of the present invention comprises a magnetic conductive tube  10 , a pole plate  20  and a bobbin  30 . 
     The magnetic conductive tube  10  is made of magnetizable material, forming a pole plate  101  on one end of the tube  10 , so that the tube  10  and the pole plate  101  together form a body. The plate  101  forms poles  102 . An inner periphery of the magnetic conductive tube  10  is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer periphery is provided to sleeve the pole plate  20  and the bobbin  30  thereon. 
     The pole plate  20  sleeved on the outer periphery of the magnetic conductive tube  10  has poles  201  which interact with a permanent magnet of a rotor (not shown) so as to rotate the motor smoothly, and the number of the poles  201  are provided in accordance with the design requirement of motor&#39;s pole number. 
     The bobbin  30  is essentially made of insulation material such as plastic, and sleeved on the outer periphery of the magnetic conductive tube  10 . The bobbin  30  sleeves tightly or loosely with the outer periphery of the magnetic conductive tube  10  according to design requirements. The bobbin  30  is positioned between the pole plate  101  and the pole plate  20 , and coil  301  is wound on the bobbin  30 , as shown in FIG.  4 . It is easy and convenient to wind the coil  301  on the bobbin  30 , before or after the magnetic conductive tube  10  and the bobbin  30  are assembled. Either way may achieve the goal of easy assembly. 
     Referring to FIGS. 3 and 4, which show the situation of the combination of the first embodiment of the present invention. The bobbin  30  is held between the pole plate  101  and the pole plate  20 , and coil  301  is wound on the outer peripheral of bobbin  30 . Insulation layer is needed between coil  301 , pole plate  101  and the pole plate  20 , to thus forms a stator. 
     Referring to FIG. 5, a brushless DC motor in accordance with the second embodiment of the present invention comprises a magnetic conductive tube  11 , a pole plate  21  and a bobbin  30 . 
     The magnetic conductive tube  11  is made of magnetizable material forming a pole plate  111  on one end, the pole plate  111  having poles  112 , the outer edge of the poles  112  extending to the opposite direction of the other pole plate  21  so as to increase the induction area of stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate  111  has a larger induction area The number of poles  112  are provided in accordance with the design requirement of the motor&#39;s pole number. An inner periphery of the magnetic conductive tube  11  is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer periphery is provided to sleeve the pole plate  21  and the bobbin  30  thereon. 
     The pole plate  21  is sleeved on the outer periphery of the magnetic conductive tube  11 , the pole plate  21  having poles  211 , and the outer edge of the poles  211  extending in an opposite direction to those of the pole plate  11  so as to increase the induction area of stator to the permanent magnet of a rotor, so that the thickness of a single plate of the pole plate  111  has a larger induction area. The number of poles  112  are provided in accordance with the design requirement of the motor&#39;s pole number. 
     The bobbin  30  is the same as in the first embodiment, and sleeved the outer peripheral of the magnetic conductive tube  10 . The bobbin  30  sleeves tightly or loosely around the outer periphery of the magnetic conductive tube  10 , the bobbin  30  is positioned between the pole plate  111  and the pole plate  21  therebetween. It is easy and convenient to wind coils on the bobbin  30  before or after the magnetic conductive tube  10  and the bobbin  30  are assembled. Either way may achieve the goal of easy manufacturing. 
     FIG. 6, shows the situation of the combination of the second embodiment of the present invention. The bobbin  30  is held between the pole plate  111  and the pole plate  21 , and coil  301  is wound on the outer peripheral of bobbin  30 . An insulated layer is provided between the coil  301 , the pole plate  111  and the pole plate  21 , and thus it forms a stator. 
     Referring to FIG. 7, a brushless DC motor in accordance with the third embodiment of the present invention comprises a magnetic conductive tube  11 , a pole plate  22  and a bobbin  30  corresponding to the second embodiment. The third embodiment further comprises an inclined portion  113 ,  222  respectively formed on the poles  112 ,  221 , which, unlike the second embodiment, form an irregular magnetic field. Because of the irregular magnetic field, the stator drives the rotor easily at the beginning of the motor start-up. 
     Referring to FIG. 8, the third embodiment of the present invention further comprises a magnetic conductive tube  11 , a pole plate  22  and a bobbin  30 . The third embodiment further comprises a lower portion  114 ,  223  instead of the inclined portion  113 ,  222  respectively formed on the poles  112 ,  221  to form an irregular magnetic field. And, the third embodiment further comprises a recessed portion  115 ,  224  respectively formed on the poles  112 ,  221  to form an irregular magnetic field, as shown in FIG.  9 . Because of the irregular magnetic field, the stator drives the rotor easily at the beginning of the motor start-up. 
     Referring to FIG. 10, a brushless DC motor in accordance with the fourth embodiment of the present invention comprises two pole plates  21 , a bobbin  30  and a magnetic conductive tube  40 . 
     The magnetic conductive tube  40  is made of magnetizable material, forming an annular flange  401  on one end so as to hold the pole plate  21  in place. An inner periphery of the magnetic conductive tube  40  is provided with a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface to sleeve the two pole plates  21  and the bobbin  30  thereon. 
     The number of pole plates  21  is more than two, the plates being sleeved on the outer surface of the magnetic conductive tube  40  to be held in place by the annular flange  401 . The pole plate  21  has poles  211 , the outer edge of the poles  211  extending in the opposite direction to those of the pole plate  11  so as to increase the induction area of the stator to relative to the permanent magnet of a rotor, so that the thickness of a single plate of the pole plate  111  has a larger induction area. The number of poles  112  are provided in accordance with the design requirement of the motor&#39;s pole number. 
     The bobbin  30  is essentially made of insulation material such as plastic, and was sleeved to the outer peripheral of the magnetic conductive tube  10 . The bobbin  30  sleeves tightly or loosely on the outer surface of the magnetic conductive tube  10 . The bobbin  30  is positioned between the pole plate  101  and the pole plate  20  therebetween and wire are coiled on the bobbin  30  thereon to form a coil  301 . It is easy and convenient to wind the coil  301  on the bobbin  30  before or after the magnetic conductive tube  10  and the bobbin  30  are assembled. Either way may achieve the goal of easy assembly. 
     FIG. 11 that shows the situation of the combination of the fourth embodiment of the present invention. The bobbin  30  is held between the two pole plates  21 , and the coil  301  wound on the outer surface of bobbin  30 . An insulated layer is provided between the coil  301  and the two pole plates  21 , to thus form a stator. 
     Referring to FIG. 12, a brushless DC motor in accordance with the fifth embodiment of the present invention comprises a bobbin  30  and two magnetic conductive tubes  50 . 
     The magnetic conductive tube  50  is made of magnetizable material forming a pole plate  501  on one end, the pole plate  501  having poles  502 , the outer edge of the poles  502  extending to an opposite direction relative to those of the other pole plate  501  so as to increase the induction area of the stator relative to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate  501  has a larger induction area. The number of poles  502  are provided in accordance with the design requirement of the motor&#39;s pole number. The magnetic conductive tubes  50  are attached to each other and form an inner peripheral which is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate  21  and the bobbin  30  thereon. 
     The bobbin  30  is essentially made of insulation material such as plastic, and was sleeved to the outer surface of the magnetic conductive tube  50 . The bobbin  30  is sleeved tightly or loosely on the outer surface of the two attached magnetic conductive tube  50 . The bobbin  30  is positioned between the two pole plates  501  therebetween. Coil  301  is wound on the bobbin  30 . It is easy and convenient to wind the coil  301  on the bobbin  30  before or after the magnetic conductive tube  50  and the bobbin  30  are assembled. Either way may achieve the goal of easy assembly. 
     FIG. 13 that shows the situation of the combination of the fifth embodiment of the present invention. The bobbin  30  is sleeved to the outer surface of the two attached magnetic conductive tubes  50 , and coil  301  is wound on the outer surface of bobbin  30 . An insulated layer is provided between the coil  301  and the pole plates  501 ), thus forming a stator to be fixed onto a supporter  53 . 
     Referring to FIG. 14, the further modification of the fifth embodiment comprises two magnetic conductive tubes  51  and  52  having different diameter. The magnetic conductive tube  51  has a smaller diameter than the magnetic conductive tube  52  such that the outer surface of the magnetic conductive tube  51  is held in the inner surface of the magnetic conductive tube  52 . The bobbin  30  is sleeved to the outer surface of the magnetic conductive tube with the large diameter. The coil  301  is wound on the outer surface of bobbin  30  and insulated layer is provided between the coil  301  and the pole plates  511 , thus forming a stator to be fixed on to a supporter  53  by the magnetic conductive tube with the smaller diameter. 
     Referring to FIG. 15, a brushless DC motor in accordance with the sixth embodiment of the present invention comprises a magnetic conductive tube  11 , a pole plate  20  and a bobbin  31 . 
     The magnetic conductive tube  11  is made of magnetizable material forming a pole plate  111  on one end, the pole plate  111  having poles  112 , the outer edge of the poles  112  extending in an opposite direction than those of the other pole plate  21  so as to increase the induction area of the stator relative to the permanent magnet of a rotor, so that the thickness of a single plate of the pole plate  111  has a larger inductive area. The number of poles  112  are provided in accordance with the design requirement of the motor&#39;s pole number. An inner periphery of the magnetic conductive tube  11  is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate  21  and the bobbin  30  thereon. 
     More than one pole plate  20  are sleeved to the outer surface of the magnetic conductive tube  10 . It has poles  201  to interact with a permanent magnet of a rotor (not shown) so as to rotate the motor smoothly, and the number of poles  201  are provided in accordance with the design requirement of motor&#39;s the pole number. 
     The bobbin  31  is essentially made of insulation material such as plastic, and sleeved to the outer surface of the magnetic conductive tube  11 . The bobbin  31  sleeves tightly or loosely to the outer surface of the magnetic conductive tube  11 , and is positioned between the pole plate  111  and the pole plate  20 , the coil  311  being wound on the bobbin  31 . It is easy and convenient to wind the coil  311  on the bobbin  31  before or after the magnetic conductive tube  11  and the bobbin  31  are assembled. Either way may achieve the goal of easy assembly. 
     The sixth embodiment further discloses a positioning structure, comprises a plurality of holes  116 ,  202  respectively defined by the pole plates  111 ,  20  thereon. On two ends of the bobbin  31  are two discs  312  which limit the coil therebetween and insulate the coil form the plates  111 ,  20 . And the two plates  312  have a plurality of posts  313  extending therefrom. The posts  313  fit into the holes  116 ,  202  so as to position easily and accurately the magnetic conductive tube  11  and the plate  111 , 20  on the bobbin  31 . Because two discs  312  insulate the coil from the plates  111 ,  20 , there is no need from provide an insulated layer which insulates the coil  301  to the plates  111 ,  20 . 
     FIG. 16 shows the situation of the combination of the sixth embodiment of the present invention. The bobbin  31  is held between the pole plate  111  and the pole plate  20 , and coil  311  is wound on the outer surface of bobbin  31 , thus and forms a stator. 
     Referring to FIG. 17, a brushless DC motor in accordance with the seventh embodiment of the present invention comprises a magnetic conductive tube  10 , a pole plate  21  and a bobbin  30 . 
     The magnetic conductive tube  10  is made of magnetizable material, forming a pole plate  101  on one end of the tube  10  so that the tube  10  and the pole plate  101  together form a body. The plate  101  forms poles  102 . An inner periphery of the tube  10  is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate  20  and the bobbin  30  thereon. The number of poles  102  are provided in accordance with the design requirement of the motor&#39;s pole number. 
     More than one pole plate  21  are sleeved on the outer surface of the magnetic conductive tube  11 , the pole plate  21  having poles  211 , the outer edge of the poles  211  extend in an opposite direction than of the other pole plate  11  so as to increase the induction area of the stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate  111  has a larger induction area. The number of poles  112  are provided in accordance with the design requirement of the motor&#39;s pole number. 
     The bobbin  30  has been disclosed as above-mentioned, and the timing of winding the coil can be selected as required. Therefore the description here is not repeated here. 
     FIG. 18, that shows the situation of the combination of the seventh embodiment of the present invention. The bobbin  30  is held between the pole plate  101  and the pole plate  21 , and coil  301  is wound on the outer surface of bobbin  30  An insulating layer is provided between the coil  301 , pole plate  101  and the pole plate  21 , thus forming a stator. 
     Referring to FIG. 19, a brushless DC motor in accordance with the eighth embodiment of the present invention comprises a magnetic conductive tube  12 , a plate  21  and a bobbin  30 . 
     The magnetic conductive tube  12  is made of magnetizable material forming a pole plate  121  on one end, the pole plate  121  having poles  122 , the outer edge of the poles  122  extending in an opposite direction than of the other pole plate  21  so as to increase the induction area of the stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate  121  has a larger induction area. The number of poles  122  are provided in accordance with the design requirement of motor&#39;s pole number. An inner peripheral of the magnetic conductive tube  12  is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate  21  and the bobbin  30  thereon. The end of the magnetic conductive tube  12  has provided thereon an annular flange  123  with a smaller diameter than the diameter of the pole plate  121 . The annular flange  123  can be processed by bending press to fix the bobbin  30  in place. 
     The pole plate  21  and the bobbin  30  have been disclosed as above-mentioned, the timing of winding the coil can be selected as required. 
     FIG. 20 shows the situation of the combination of the eighth embodiment of the present invention. The bobbin  30  is held between the pole plate  121  and the pole plate  21 , an annular flange  123  is bent and positioned to insure that the pole plate  21  and the bobbin  30  are held in place, and coil  301  is wound on the outer surface of bobbin  30 . An insulated layer provided between the coil  301 , the pole plate  121  and the pole plate  21 , thus forming a stator. 
     Referring to FIG. 21, a brushless DC motor in accordance with the ninth embodiment of the present invention comprises a pole plate  21  and a magnetic conductive tube  60 . 
     The magnetic conductive tube  60  is made of magnetizable material forming a pole plate  601  on one end, the pole plate  601  having poles  602 , the outer edge of the poles  602  extending in an opposite direction than the other pole plate  21  so as to increase the induction area of stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate  601  has a larger induction area. The number of poles  602  are provided in accordance with the design requirement of the motor&#39;s pole number. An inner periphery of the magnetic conductive tube  60  is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor. The contact surface between coil  32  and outer surface of magnetic conductive tube  60  and pole plate  601  need insulation treatment and forms an insulation layer. Therefore, the outer surface of magnetic conductive tube  60  provides pole plate  21  to sleeve onto and the coil  32  may be wound onto it. 
     The pole plate  21  is sleeved on the outer surface of the magnetic conductive tube  11 , the pole plate  21  having poles  211 , the outer edge of the poles  211  extending in an opposite opposite direction than the other pole plate  602  so as to increase the induction area of stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate  21  has a larger induction area. The number of poles  211  are provided in accordance with the design requirement of the motor&#39;s pole number. The contact surface between the pole plate  21  and coil  32  needs insulation treatment to form an insulated layer. 
     Referring to FIG. 23, a brushless DC motor in accordance with the tenth embodiment of the present invention comprises a pole plate  21  and a magnetic conductive tube  61  which is the same as the ninth embodiment. The contact surface between coil  32  and the pole plate  21  and pole plate  611  needs insulation treatment to form an insulated layer. The magnetic conductive tube  61  further comprises a smaller diameter at an end  613 . A ladder-shaped comer  614  is formed by the different diameter on the outer surface of the magnetic conductive tube  61  for attaching and positioning the pole plate  21  (as shown in FIG.  24 ). A coil  32  may be wound on the outer surface of the magnetic conductive tube  61  at the section between the pole plate  611  and the pole plate  21 , and thus it forms a stator. 
     Referring to FIGS. 25 and 26, a rotor  70  and a circuit board  702  are assembled to form a motor corresponding to that of the second embodiment of the present invention. The second embodiment mainly comprises the magnetic conductive tube  11 , the pole plate  21 , the bobbin  30 , a rotor  70  and a circuit board  702 . The circuit board  702  mainly sleeves to the outer surface of the magnetic conductive tube  11  so as to allow a Hall IC  703  of the circuit board  702  to response to a permanent magnet  704  of the rotor  70 . An inner periphery of the magnetic conductive tube  11  is provided to contain a bearing element therein for extending through a shaft  701  of the rotor  70  to form a brushless motor. 
     Referring to FIG. 27, a fixing member  705  is combined with the present invention. The fixing member  705  like a substrate or a case of an other product having a hole  706  through which to combine with the magnetic conductive tube  11  by means of an interference fit between different diameter, or by any other combination method. 
     FIG. 28 shows the present invention brushless DC. motor (not labeled) and a case  82  combined together to form a cooler device which is consists of the magnetic conductive tube  11 , the pole plate  21 , the bobbin  30  and a circuit board  702 . Then the magnetic conductive tube  11  is held in a hole  83  of the case  82  or a conventional heat sink  86  with fins or posts(as shown in FIG.  29 ). The inner peripheral of magnetic conductive tube  11  is provided to contain a bearing element(not shown) for extending through a shaft  81  of impeller  80 . The impeller  80  further comprises a plurality of blades  84  and permanent magnets  85 . Therefore, the combined cooler device may achieve the cooling results. 
     A brushless DC motor of the present invention as defined in claim  1  reduces the complexity and cost of manufacture of conventional metal tube and pole plate, and reduces the thickness of a stator by means of reducing the thickness of the annular flange protruded on the outside of the pole plate. 
     A brushless DC motor of the present invention as defined in claim  2 ,  9 ,  18 ,  24 ,  44  and  50  includes a magnetic conductive tube that reduces the complexity and cost of manufacture. 
     A brushless DC motor of the present invention as defined in claim  3 ,  10 ,  19 ,  25 ,  32 ,  37 ,  59 ,  63 ,  67 ,  71 ,  75 ,  79  includes a magnetic conductive tube on which a fixed member or a pole plate is mounted to hold the fixed member and the pole plate tightly. 
     A brushless DC motor of the present invention as defined in claim  4 ,  11 ,  20 ,  26 ,  33 ,  38  includes a magnetic conductive tube on which a pole plate is positioned to provide better positioning effect. 
     A brushless DC motor of the present invention as defined in claim  5 ,  12 ,  17  includes a larger area of the poles of a pole plate adjacent to the permanent magnet of the rotor. It has the same effect as an inducting area formed by a plurality of silicon steel plates. Further it may reduce the complexity of manufacturing and material cost of a plurality of silicon steel plates. 
     A brushless DC motor of the present invention as defined in claim  6 ,  7 ,  13 ,  14 ,  21 ,  22 ,  27 ,  28 ,  34 ,  35 ,  39 ,  40 ,  47 ,  48 ,  53 ,  54  includes a pole plate capable of forming an irregular magnetic field of the stator. Because of the irregular magnetic field, the stator drives the rotor easily at the start-up to avoid the dead point problem. 
     A brushless DC motor of the present invention as defined in claim  8 ,  23  reduces the complexity and cost of manufacture of conventional metal tube and pole plate, and reduces the thickness of a stator by means of reducing the thickness of the annular flange protruded on the outside of the pole plate. The present invention comprises a bobbin provides insulation between a coil and a magnetic conductive tube, and then a coil is wound to the bobbin after it is assembled or before it is assembled to the magnetic conductive tube according to need. 
     A brushless DC motor of the present invention as defined in claim  15 ,  29 ,  41 ,  55  includes a disc insulating the magnetic conductive tube to the coil, when coil is wound on the bobbin, the disc limits the coil in between the disc, thus result in better winding. 
     A brushless DC motor of the present invention as defined in claim  16 ,  30 ,  42 ,  56  includes a bobbin having a plurality of posts extending through a plurality of holes of two pole plates so that the two pole plates are capable of being positioned precisely and conveniently. 
     A brushless DC motor of the present invention as defined in claim  31  includes a pole plate extended to form poles with a larger inductive area than that of the plates adjacent to the permanent magnet of the rotor. Thus the overall height of the stator is not affected. It has the same effect of an inductive area formed by a plurality of silicon steel plates. And reduce the manufacturing and material cost. 
     A brushless DC motor of the present invention as defined in claim  36  includes a pole plate extended to form poles with larger inductive area than the plates adjacent to the permanent magnet of the rotor. Thus the overall height of the stator is not affected even though the magnetic conductive tube has an annular flange. It has the same effect as an inductive area formed by a plurality of silicon steel plates, and reduces the manufacturing and material cost. A coil is wound to the bobbin after or before it is assembled according to need. Either way may achieve the goal of easy assembly. 
     A brushless DC motor of the present invention as defined in claim  43  reduces the complexity and cost of manufacture of a conventional metal tube and pole plate, and reduces the thickness of the stator by means of reducing the thickness of the annular flange protruded on the outside of the pole plate. The present invention includes a larger area of the poles of a pole plate adjacent to the permanent magnet of the rotor. It has the same effect of an inducting area formed by a plurality of silicon steel plates. Further it may reduce the complexity of manufacturing and material cost of a plurality of silicon steel plates. 
     A brushless DC motor of the present invention as defined in claim  45 ,  46 ,  51 ,  52  includes a shaft of a supporter which combines the shaft and magnetic conductive tube so that the stator may be easily assembled. 
     A brushless DC motor of the present invention as defined in claim  49  reduces the complexity and cost of manufacture of conventional metal tube and upper pole plate, and reduces the thickness of a stator by means of reducing the thickness of the annular flange protruded above the upper pole plate. The present invention includes a larger inductive area of the poles of a pole plate adjacent to the permanent magnet of the rotor. It has the same effect of an inductive area formed by a plurality of silicon steel plates. Further it may reduce the complexity of manufacturing and material cost of a plurality of silicon steel plates. A coil is wound to the bobbin after or before it is assembled according to need. Either way may achieve the goal of easy assembly. 
     A brushless DC motor of the present invention as defined in claim  57 ,  61 ,  81 ,  82  reduces the complexity and the cost of manufacture, and the thickness of the motor. 
     A brushless DC motor of the present invention as defined in claim  58 ,  62 ,  66 ,  70 ,  74 ,  78  includes a fixed member to mount the motor in order to reduce the fixing element, the material and manufacturing cost. 
     A brushless DC motor of the present invention as defined in claim  60 ,  64 ,  68 ,  72 ,  76 ,  80  provides a better position result when the circuit board is assembled. 
     A brushless DC motor of the present invention as defined in claim  65 ,  69 ,  73 ,  77 ,  83 ,  84  reduces the complexity and the cost of manufacture, and the thickness of the motor. The present invention includes a larger inductive area of the poles of a pole plate adjacent to the permanent magnet an the rotor. It has the same effect of an inducting area formed by a plurality of silicon steel plates. Further it may reduce the complexity of manufacturing and material cost of a plurality of silicon steel plates. 
     A brushless DC motor of the present invention as defined in claim  85 ,  86 ,  87 ,  88  provides a heat-dissipating device and reduces the complexity and the cost of manufacture, and the thickness of the heat-dissipating device. 
     A brushless DC motor of the present invention as defined in claim  89  through  100  provides a heat-dissipating device and reduces the complexity and the cost of manufacture, and the thickness of the heat-dissipating device. The edge of the plate is extended to form a pole in order to increase the inductive area of the plates adjacent to the permanent magnet of the rotor so as to greatly reduce material cost. 
     A brushless DC motor of the present invention as defined in claim  101  through  108  provides a heat-dissipating device and reduces the complexity and the cost of manufacture. In addition, the frame is mounted to the heat sink at suitable position to form a heat-dissipating device. 
     The invention may have various modifications without departing from main spirit and novel features. Thus the preferred embodiment presented above are examples for explanation purpose not to limit the scope of the invention. The scope of this invention is covered by the patent claims appended, not by the detailed description of the preferred embodiment. Further more, any equivalent modification and variation of the claims also fall within the scope of the invention.