Abstract:
A wheel driven mechanism adapted for driving a vehicle without motor is disclosed to include a rotor defining therein an accommodation chamber, a plurality of permanent magnets arranged in the accommodation chamber of the rotor, a stator having one or a number of stator segments, and one or a number of electromagnets located on the stator segment(s) within the accommodation chamber and facing toward the permanent magnets at the stator to enhance the convenience of use of the wheel driven mechanism.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relative to a wheel driven mechanism and more particularly to such a wheel driven mechanism specially designed for driving a vehicle without a motor. 
         [0002]    Referring to  FIG. 1 , a conventional handwheel for electric wheelchair is shown. As illustrated, the handwheel  10  comprises a wheel rim  11 , a plurality of brackets  14 , a plurality of permanent magnets  13 , and a plurality of electromagnets  16 , wherein the permanent magnets  13  are arranged along the wheel rim  11 , each bracket  14  has its one end connected to the axle center  17  of the wheel rim  11  and the electromagnets  16  are arranged at the other ends of the brackets  16 . During operation, the user can hold and rotate the wheel rim  10 . The permanent magnets  13  are arranged in NS pole pairs and evenly located on the inner surface of the wheel rim  11  to face toward the axle center  17 . Further, the permanent magnets  13  of N-S poles are in alternate arrangement. As shown in  FIG. 1 , the permanent magnets  13  of N-S poles are evenly and alternatively arranged over the whole inner surface of the wheel rim  11  in radial direction to face toward the axle center  17  of the wheel rim  11 . 
         [0003]    The electromagnets  16  are disposed corresponding to the inner side of the wheel rim  11 . During operation, power supply is provided to the electromagnets  16 , causing the electromagnets  16  to create a magnetic field relative to the permanent magnets  13  of NS pole pairs. The magnetic coupling interaction between the electromagnets  16  and the permanent magnets  13  causes the wheel rim  11  to rotate relative to the axle center  17 . 
         [0004]    In  FIG. 1 , the electromagnets  16  are radially arranged to face toward the permanent magnets  13  at the inner side of the wheel rim  11 . The electromagnets  16  are divided into two groups, namely, the first electromagnet group  121  and the second electromagnet group  123 . The first electromagnet group  121  is arranged at one end of a first bracket  141 , which has its other end located on the axle center  17  of the wheel rim  11 . Similarly, the second electromagnet group  123  is arranged at one end of a second bracket  143 , which has its other end located on the axle center  17  of the wheel rim  11 . Thus, the first electromagnet group  121  and the second electromagnet group  123  are symmetric relative to the axle center  17 . 
         [0005]    Further, a gap  15  is defined between the electromagnets  16  and the permanent magnets  13  so that the wheel rim  11  carrying the permanent magnets  13  is rotatable relative to the electromagnets  16  at the brackets  14 . However, when the user operates the handwheel  10 , the fingers or a part of the body of the user may be jammed in the gap  15  accidentally, causing injury. 
         [0006]    Further, after a certain period of time in use, the wheel rim  11  may be deformed, resulting in a variation of the gap  15  between the electromagnets  16  at the brackets  14  and the permanent magnets  13  at the wheel rim  11 . When this condition occurs, the magnetic coupling interaction between the electromagnets  16  and the permanent magnets  13  will be changed, causing wheel rim performance drop or wheel rim damage. 
         [0007]    Therefore, there is a strong demand for a wheel driven mechanism, which eliminates the aforesaid problems. 
       SUMMARY OF THE PRESENT INVENTION 
       [0008]    It is, therefore, an object of the present invention to provide a wheel driven mechanism, which comprises a rotor defining therein an accommodation chamber, a stator having at least one stator segment, and at least one electromagnet set arranged at the at least one stator segment in which a manner that the electromagnet set and/or the stator segment is disposed in the accommodation chamber, preventing jammed fingers during operation. 
         [0009]    It is another object of the present invention to provide a wheel driven mechanism, which further comprises a bearing arranged between the rotor and the stator to maintain the gap between the permanent magnets at the stator and the electromagnet set at the stator during relative motion between the rotor and the stator, facilitating smooth relative motion between the rotor and the stator. 
         [0010]    It is still another object of the present invention to provide a wheel driven mechanism, which further comprises at least one adjustment unit arranged between the stator segment and the bracket of the stator to maintain the relative positioning between the permanent magnets at the rotor and the electromagnet set at the stator segment, assuring high reliability of the operation performance of the wheel driven mechanism. 
         [0011]    It is still another object of the present invention to provide a wheel driven mechanism, which further comprises at least one waterproof gasket arranged between the rotor and the stator to protect the accommodation chamber of the rotor against outside moisture, avoiding contact between the outside moisture and the electromagnet set and/or the permanent magnets in the accommodation chamber and prolonging the working life of the wheel driven mechanism. 
         [0012]    To achieve these and other objects of the present invention, the present invention provides a wheel driven mechanism, comprising: a rotor defining therein an accommodation chamber; a plurality of permanent magnets mounted inside the accommodation chamber of the rotor; a stator comprising at least one stator segment; and at least one electromagnet set arranged at the stator segment and disposed inside the accommodation chamber of the rotor and facing toward the permanent magnets. 
         [0013]    In one embodiment of aforesaid wheel driven mechanism, further comprises a gap defined between the permanent magnets at the rotor and the electromagnet set at the stator segment. 
         [0014]    In one embodiment of aforesaid wheel driven mechanism, further comprises at least one bearing set between the rotor and the at least one stator segment. 
         [0015]    In one embodiment of aforesaid wheel driven mechanism, wherein the stator comprises a bracket, and the stator segment is located on the bracket. 
         [0016]    In one embodiment of aforesaid wheel driven mechanism, further comprises at least one adjustment unit set between the bracket and the stator segment and controllable to adjust the relative positioning between the electromagnet set at the stator segment and the permanent magnets at the rotor. 
         [0017]    In one embodiment of aforesaid wheel driven mechanism, further comprises at least one waterproof gasket set between the rotor and the stator to watertightly seal the accommodation chamber into an enclosed space. 
         [0018]    In one embodiment of aforesaid wheel driven mechanism, further comprises a drainage passage set between the rotor and the stator. 
         [0019]    In one embodiment of aforesaid wheel driven mechanism, wherein the drainage passage is disposed between the waterproof gasket and the stator. 
         [0020]    In one embodiment of aforesaid wheel driven mechanism, wherein each the electromagnet set comprises at least one coil and at least one magnetic flux conducting unit, the at least one coil being respectively wound on the at least one magnetic flux conducting unit. 
         [0021]    In one embodiment of aforesaid wheel driven mechanism, wherein the rotor is an annular member, and the accommodation chamber is an annular chamber defined in the rotor. 
         [0022]    In one embodiment of aforesaid wheel driven mechanism, wherein the rotor is a tube handwheel of a wheelchair. 
         [0023]    In one embodiment of aforesaid wheel driven mechanism, wherein the rotor is a driving wheel of a vehicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a schematic drawing illustrating the structure of a handwheel of a conventional electric wheelchair. 
           [0025]      FIG. 2  is a schematic perspective front view of a wheel driven mechanism in accordance with a first embodiment of the present invention. 
           [0026]      FIG. 3  is a schematic sectional view of the wheel driven mechanism in accordance with the first embodiment of the present invention. 
           [0027]      FIG. 4  is a schematic sectional view of a wheel driven mechanism in accordance with a second embodiment of the present invention. 
           [0028]      FIG. 5  is a schematic perspective front view of a wheel driven mechanism in accordance with a third embodiment of the present invention. 
           [0029]      FIG. 6  is a schematic sectional view of the wheel driven mechanism in accordance with the third embodiment of the present invention. 
           [0030]      FIG. 7  is a schematic sectional view of a wheel driven mechanism in accordance with a fourth embodiment of the present invention, illustrating, a waterproof gasket and a drainage passage provided between a rotor and a stator. 
           [0031]      FIG. 8  is a schematic perspective front view of a wheel driven mechanism in accordance with a fifth embodiment of the present invention, illustrating a configuration of one stator segment and one electromagnet set. 
           [0032]      FIG. 9  is a schematic perspective front view of a wheel driven mechanism in accordance with a sixth embodiment of the present invention, illustrating a configuration of three stator segments and three electromagnet sets. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    Please referring to  FIGS. 2 and 3 , a schematic perspective front view and a schematic sectional view of a wheel driven mechanism in accordance with a first embodiment of the present invention are shown. As illustrated, the wheel driven mechanism  20  comprises a rotor  21 , a plurality of permanent magnets  23 , and a stator  25 . The stator  25  comprises at least one stator segment  251  and at least one bracket  253 . The stator segment  251  is supported on the bracket  253 . The stator segment  251  holds at least one electromagnet set  27 . The electromagnet set  27  at the stator segment  251  corresponds to the permanent magnets  23  at the rotor  21 . A gap  24  is defined between the electromagnet set  27  at the stator segment  251  and the permanent magnets  23  at the rotor  21  so that the rotor  21  is rotatable relative to the stator  25 . 
         [0034]    The rotor  21  defines therein an accommodation chamber  22 . In this embodiment, the rotor  21  is an annular member so that the accommodation chamber  22  has an annular profile. The stator segment  251  and the electromagnet set  27  are accommodated in the accommodation chamber  22  in such a manner that the electromagnet set  27  at the stator segment  251  faces toward the permanent magnets  23  at the rotor  21 . Further, the electromagnet set  27  at the stator segment  251  is periodically in a magnetic flux coupling relationship with the permanent magnets  23  at the rotor  21 . 
         [0035]    The permanent magnets  23  in this embodiment are arranged in the accommodation chamber  22  of the rotor  21  in NS pole pairs over the whole or a part of the inner surface of the rotor  21 . Further, the N or S pole of each permanent magnet  23  is disposed in axial direction. Further, the permanent magnets  23  of N-S poles are in alternate arrangement. 
         [0036]    The bracket  253  of the stator  25  is fixedly mounted at the axle center  29  of the wheel driven mechanism  20 . Each of the two opposite ends of each bracket  253  has stator segment  251  arranged thereon. Each stator segment  251  carries electromagnet set  27 . Thus, the electromagnet set  27  and/or the stator segment  251  is arranged in a symmetrical manner relative to the axle center  29 . Further, each electromagnet set  27  comprises a plurality of, for example, 6 electromagnets  271 . 
         [0037]    In actual application, if a three-phase power supply is to be provided to the wheel driven mechanism  20 , the number of the electromagnets  271  of the electromagnet set  27  should be a multiple of 3, for example, 3, 6, 9, etc. If a two-phase power supply is to be provided to the wheel driven mechanism  20 , the number of the electromagnets  271  of the electromagnet set  27  should be a multiple of 2, for example, 2, 4, 6, etc. 
         [0038]    The electromagnets  271  of each electromagnet set  27  are made from coils. When electrically conducted, the electromagnets  271  of each electromagnet set  27  create a magnetic field. In different embodiments, coils can be wound around a magnetic flux conducting unit, for example, a cylindrical magnetic flux conducting core prepared by ferrite (Fe), cobalt (Co) or nickel (Ni), for creating a high strength of magnetic field to enhance the torque of the wheel driven mechanism  20 . 
         [0039]    According to the present invention, the electromagnet set  27  and/or the stator segment  251  is accommodated in the accommodation chamber  22  of the rotor  21  so that the gap  24  between the stator  25  and the rotor  21  will not be apparently exposed to the external structure of the wheel driven mechanism  20 , preventing the user&#39;s fingers from being jammed between the stator  25  and the rotor  21  during operation and increasing the level of safety of the use of the wheel driven mechanism  20 . 
         [0040]    To enhance the efficiency of the wheel driven mechanism  20 , at least one bearing  26  may be set between the stator segment  251  of the stator  25  and the rotor  21 . The bearing  26  each can be a ball bearing or needle bearing. In actual application, the bearing  26  can be arranged at the stator segment  251  of the stator  25  or the rotor  21 . Subject to the arrangement of the bearing  26 , the gap  24  between the permanent magnets  23  at the rotor  21  and the electromagnet set  27  at the stator segment  251  of the stator  25  is maintained during relative motion between the rotor  21  and the stator  25 , facilitating smooth relative motion between the rotor  21  and the stator  25 . 
         [0041]    In this first embodiment, the bracket  253  is adjustably connected to the stator segment  251  by at least one adjustment unit  255 . By means of the adjustment unit  255 , the user can adjust the relative positioning between the electromagnet set  27  at the stator segment  251  of the stator  25  and the bracket  253  to compensate the amount of deformation of the roundness of the wheel driven mechanism  20 . The adjustment unit  255  has a deformation characteristic. For example, each adjustment unit  255  can be a spring member or sliding block. 
         [0042]    Normally, the wheel driven mechanism  20  may deform due to uneven external pressure after a certain period of time in use, resulting in non-roundness of the rotor  21 . Following shape change of the rotor  21 , the overlapped area between the electromagnet set  27  at the stator segment  251  and the permanent magnets  23  at the stator  21  may be contracted, affecting the performance of the wheel driven mechanism  20 . 
         [0043]    Subject to the use of the adjustment unit  255  and/or the bearing  26 , the relative positioning between the permanent magnets  23  at the rotor  21  and the electromagnet set  27  at the stator segment  251  of the stator  25  is constantly maintained unchanged, avoiding deformation of the rotor  21  or affecting the operation performance of the wheel driven mechanism  20 . 
         [0044]    Referring to  FIG. 4 , a wheel driven mechanism in accordance with a second embodiment of the present invention is shown. As illustrated, the wheel driven mechanism  30  comprises a rotor  21 , a plurality of permanent magnets  23 , a stator  25  comprising at least one stator segment  251 , and at least one electromagnet set  27  installed in the stator segment  251  of the stator  25 . Further, the electromagnet set  27  comprises a plurality of electromagnets  271 . The rotor  21  defines therein an accommodation chamber  22 . The electromagnet set  27  and/or the stator segment  251  of the stator  25  is accommodated in the accommodation chamber  22  of the rotor  21 . The electromagnet set  27  faces toward the permanent magnets  23  with a gap  24  left therebetween so that the rotor  21  is rotatable relative to the stator  25 . 
         [0045]    In this embodiment, the wheel driven mechanism  30  further comprises a waterproof gasket  36  set between the rotor  21  and the stator  25 . The waterproof gasket  36  can be mounted at the rotor  21  or stator  25  to watertightly seal the accommodation chamber  22  of the rotor  21 , avoiding permeation of external moisture into the accommodation chamber  22  to wet the at least one electromagnet set  27  in the accommodation chamber  22 . 
         [0046]    The wheel driven mechanism  30  further comprises a drainage passage  38  disposed between the rotor  21  and the stator  25  for expelling water out of the accommodation chamber  22  by means of a centrifugal force generated during the rotation of the rotor  21 . The drainage passage  38  can be set between the waterproof gasket  36  and stator  25  so that a part of moisture can be guided by the drainage passage  38  to the outside of the accommodation chamber  22  before touching the waterproof gasket  36 , lowering the chance of moisture intrusion into the accommodation chamber  22 . Further, the internal air pressure in the rotor  21  will become higher than the external air pressure to lower the chance of moisture intrusion into the accommodation chamber  22  upon a rise in temperature in the accommodation chamber  22  due to conduction of an electric current through the electromagnets  271 . 
         [0047]    As the electromagnets  271  and the permanent magnets  23  are mainly prepared by ferrite (Fe), cobalt (Co) or nickel (Ni), the electromagnets  271  or the permanent magnets  23  may be rusted or damaged when putting into contact with moisture for a long period of time. By means of the arrangement of the waterproof gasket  36  and/or the drainage passage  38 , the electromagnets  271  and the permanent magnets  23  are isolated from external moisture, effectively prolonging the working life of the wheel driven mechanism  30 . 
         [0048]    Please referring to  FIG. 5  and  FIG. 6 , a schematic perspective front view and a schematic sectional view of the wheel driven mechanism in accordance with a third embodiment of the present invention. As illustrated, the wheel driven mechanism  40  comprises a rotor  41 , a plurality of permanent magnets  43 , a stator  45  comprising at least one stator segment  451 , and at least one electromagnet set  47  comprising a plurality of electromagnets  471  arranged at the at least one stator segment  451 . The rotor  41  defines therein an accommodation chamber  42 . The electromagnet set  47  and/or the stator segment  451  is accommodated in the accommodation chamber  42  of the rotor  41 . Further, the electromagnet set  47  faces toward the permanent magnets  43  in the accommodation chamber  42  with a gap  44  left therebetween so that the rotor  41  is rotatable relative to the stator  45 . 
         [0049]    In this embodiment, the rotor  41  comprises a bracket  411 , and the permanent magnets  43  are mounted at the bracket  411 . The stator segment  451  is configured to surround the permanent magnets  43 , keeping the electromagnet set  47  at stator segment  451  to face toward the permanent magnets  43  at the bracket  411 . For example, the stator segment  451  can be configured to have a U-shaped profile for surrounding the permanent magnets  43  at the bracket  411 . 
         [0050]    Further, the U-shaped stator segment  451  can be arranged to surround a part of the bracket  411  with at least one bearing  49  set between the stator segment  451  and the bracket  411 , enhancing the relative positioning stability between the permanent magnets  43  and the electromagnet set  47  and the operation performance of the wheel driven mechanism  40 . 
         [0051]    Further, the permanent magnets  43  in this embodiment are arranged in NS pole pairs. Further, the N or S pole of each permanent magnet  43  is disposed in radial direction. 
         [0052]    In actual application, a waterproof gasket  46  and/or a drainage passage  48  can be provided between the rotor  41  and the stator  45 , as shown in  FIG. 7 , keeping the accommodation chamber  42  of the rotor  41  in an enclosed condition to lower the chance of moisture intrusion into the accommodation chamber  42 . Further, the internal air pressure in the rotor  41  will become higher than the external air pressure to lower the chance of moisture intrusion into the accommodation chamber  42  and to prolong the working life of the wheel driven mechanism  40  upon a rise in temperature in the accommodation chamber  42  due to conduction of an electric current through the electromagnets  471 . 
         [0053]    Further, the winding condition of the electromagnet sets  27 / 47  and the relative arrangement of the permanent magnets  23 / 43  enables the air gap flux to be axially or radially direction. For example, the air gap flux of electromagnet sets  27  and permanent magnets  23  of the wheel driven mechanism  20 / 30  in  FIG. 3  and  FIG. 4  are axially directed where the windings of the electromagnet sets  27  extend in a parallel manner relative to the wheel driven mechanism  20 / 30 , and the axle center of the rotor  21  and/or stator  25 . The air gap flux of electromagnet sets  47  and permanent magnets  43  of the wheel driven mechanism  40  in  FIGS. 5-7  are radially directed where the windings of the electromagnet sets  47  extend along the radius direction of the wheel driven mechanism  40 , rotor  41  and/or stator  45 . The aforesaid two winding methods can be selectively used to make the wheel driven mechanism subject to actual requirements. 
         [0054]    In the aforesaid various embodiments, the wheel driven mechanism  20 / 30 / 40  mainly comprises two stator segments  251 / 451  and two electromagnet sets  27 / 47  respectively located on the two ends of the bracket  253 . However, in the embodiment shown in  FIG. 8 , only one stator segment  251 / 451  and one electromagnet set  27 / 47  are provided. Further, the number of the stator segments  251 / 451  and the number of the electromagnet sets  27 / 47  can be more than 2. For example, in the embodiment shown in  FIG. 9 , the wheel driven mechanism comprises three stator segments  251 / 451  and three electromagnet sets  27 / 47 . 
         [0055]    The aforesaid wheel driven mechanisms  20 / 30 / 40  are designed for driving a vehicle, for example, a wheelchair, electric bicycle, motorcycle, etc., wherein the rotor  21 / 41  can be the driving wheel of a vehicle or the tube handwheel of a wheelchair.