Abstract:
The present invention provides a stator core winding method for a motor and a structure thereof. The method includes preparing a stator core including a plurality of core cavities; winding a pair of second-phase coils into the plurality of core cavities of the stator core; winding a pair of first-phase coils, a pair of the second-phase coils and two pairs of third-phase coils into the plurality of core cavities of the stator core; and winding two pairs of the first-phase coils, a pair of the second-phase coils and a pair of the third-phase coils into the plurality of core cavities of the stator core.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a motor, and more particularly to a stator core winding method for a motor. 
     BACKGROUND OF THE INVENTION 
     A stator of a motor generally includes a stator core made of a magnetic material, which includes an axially extended inner hole to receive a rotor. Generally, the stator core is made by stacking up and arranging multiple similar sheets in a frame and fixing them with a clamp or riveting them through projected points. A plurality of coils formed by insulated conductive wires are inserted into determined stator cavities in the stator core to render the coils to form U-turn areas in the end portion of the stator core. The coils are connected to one another to form coil assemblies or poles. The coils forming the so-called stator winding are usually covered with paints or enamels to form protective covering layers at the periphery of the coils, so as to form better insulation among the coils. 
     The coil assemblies included by a single-speed motor establish at least one set of winding. The coil assemblies are wound by a winding machine and are disposed on a coil inserting jig. The formed coils are inserted into the stator through for example the inserting jig subsequently, and therefore the coils are substantially aligned with the core cavities in the stator core. However, the traditional winding method is divided into three stages. Three single phase coils are inserted into the core cavities in the positions spaced apart with angles of 120 degrees during each winding stage, and the positions of the core cavities inserted in each stage are staggered with one another. The inductance unbalance of the three phase inductance of the stator core completed by the traditional method usually exceeds 1%, for example 2-3%. 
     Therefore, the motor manufactured with the stator core completed by the traditional method suffers poor performance because of high inductance unbalance. 
     Accordingly, there is still a need for a solution which can solve the aforementioned problem of high inductance unbalance. 
     SUMMARY OF THE INVENTION 
     To solve the aforementioned problem of high inductance unbalance, the present invention provides a stator core winding method for a motor and a structure thereof. 
     In one aspect, the present invention provides a stator core winding method for a motor, comprising preparing a stator core including a plurality of core cavities; winding a pair of second-phase coils into the plurality of core cavities of the stator core; winding a pair of first-phase coils, a pair of the second-phase coils and two pairs of third-phase coils into the plurality of core cavities of the stator core; and winding two pairs of the first-phase coils, a pair of the second-phase coils and a pair of the third-phase coils into the plurality of core cavities of the stator core. 
     Another advantage of the present invention is that the stator core winding method for the motor and the structure thereof of the present invention can enhance the performance of the motor greatly. 
     These and other advantages will become apparent from the following description of preferred embodiments taken together with the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be understood by some preferred embodiments and detailed descriptions in the specification and the attached drawings below. The identical reference numbers in the drawings refer to the same components in the present invention. However, it should be appreciated that all the preferred embodiments of the invention are only for illustrating but not for limiting the scope of the claims and wherein: 
         FIG. 1  illustrates a diagram of a stator core having nine core cavities in accordance with one embodiment of the present invention; 
         FIG. 2  illustrates a vertical cross-sectional view of an inserting jig in accordance with one embodiment of the present invention; 
         FIG. 3  illustrates a top view of strip-shaped portions of the inserting jig of  FIG. 2  in accordance with one embodiment of the present invention; 
         FIG. 4  illustrates a horizontal cross-sectional view of each pushing element of the inserting jig of  FIG. 2  in accordance with one embodiment of the present invention; 
         FIG. 5  illustrates a vertical cross-sectional view of the inserting jig disposed with the coils and the stator core thereon in accordance with one embodiment of the present invention; 
         FIG. 6  illustrates a diagram of the completed stator core of the motor in accordance with one embodiment of the present invention; 
         FIG. 7  illustrates a flow chart of the stator core winding method for the motor in accordance with one embodiment of the present invention; 
         FIG. 8  illustrates a flow chart of the stator core winding method for the motor in accordance with one embodiment of the present invention; and 
         FIG. 9  illustrates a wiring diagram of the coils in each core cavity in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention will now be described with the preferred embodiments and aspects and these descriptions interpret structure and procedures of the invention only for illustrating but not for limiting the claims of the invention. Therefore, except the preferred embodiments in the specification, the present invention may also be widely used in other embodiments. 
     The present invention discloses a stator core winding method for a motor. The stator core of the motor generally is made of silicon steel sheets which are stacked up along the rotation axis of the motor. A plurality of core cavities are formed in the stator core to dispose coils of different phases into the core cavities. In one embodiment, the number of the core cavities may be 9, 12, 15 or 18. The aforementioned number of the core cavities is illustrated for example, but not for limiting the present invention. In one embodiment, as shown in  FIG. 1 , the stator core  10  includes a first core cavity  101 , a second core cavity  102 , a third core cavity  103 , a fourth core cavity  104 , a fifth core cavity  105 , a sixth core cavity  106 , a seventh core cavity  107 , an eighth core cavity  108  and a ninth core cavity  109 . As shown in  FIG. 1 , every core cavity includes a cavity opening  110  formed adjacent to the center of the stator core  10  in order for the coils to pass therethrough and enter every core cavity. A cavity wall  111  is formed between every core cavity. 
     The stator core winding method for the motor of the present invention utilizes an inserting jig to introduce the coils into every core cavity in the stator core  10 . FIG.  2  illustrates a vertical cross-sectional view of the inserting jig in accordance with one embodiment of the present invention.  FIG. 3  illustrates a top view of the strip-shaped portion of the inserting jig of  FIG. 2 .  FIG. 5  illustrates a vertical cross-sectional view of the inserting jig disposed with the coils and the stator core thereon in accordance with one embodiment of the present invention. As shown in  FIGS. 2 ,  3  and  5 , the inserting jig  20  includes a plurality of strip-shaped portions  201  arranged annularly and spaced apart in a determined distance to pass through the coils  30  of different phases and dispose the coils  30  thereon. The diameter of the outer circle of the ring shape formed by the plurality of strip-shaped portions  201  is substantially equal to the diameter of the inner circle formed by the edge of the cavity wall  111  of the stator core  10  adjacent to the center of the stator core  10 . The number of the strip-shaped portions  201  corresponds to the number of the core cavities in the stator core  10 . In one embodiment, the number of the strip-shaped portions  201  may be 9, 12, 15 or 18. The aforementioned number of the strip-shaped portions  201  is described for illustrating the present invention but not for limiting the present invention. The positions of the strip-shaped portions  201  correspond to the positions of the cavity walls  111  between every core cavities. 
     As shown in  FIGS. 2 and 5 , a plurality of pushing elements, for example three vertically connected pushing elements  2021 ,  2022  and  2023 , are disposed in the cylindrical space formed by the strip-shaped portions  201  to push the coils  30  of different phases on the strip-shaped portions  201  upwards and into the core cavities in the stator core  10 .  FIG. 4  illustrates a cross-sectional view of each pushing element  2021 - 2023 . In one embodiment, as shown in  FIG. 4 , the pushing elements  2021 - 2023  include one or a plurality of projected portions  203  adjacent to the edges of the strip-shaped portions  201  to push specific coils  30  disposed above specific pushing element upwards and into specific core cavity in the stator core  10 . The positions of the projected portions  203  of the pushing elements  2021 - 2023  correspond to the positions of the cavity walls  111  between the core cavities to be introduced with the coils during each stage. In one embodiment, as shown in  FIG. 4 , the position of the projected portion  203  of the pushing element  2021  corresponds to the position of the cavity wall  111  between the eighth core cavity  108  and the ninth core cavity  109 . The positions of the projected portions  203  of the pushing element  2022  respectively correspond to the positions of the cavity wall  111  between the first core cavity  101  and the ninth core cavity  109 , the cavity wall  111  between the second core cavity  102  and the third core cavity  103 , the cavity wall  111  between the fourth core cavity  104  and the fifth core cavity  105  and the cavity wall  111  between the sixth core cavity  106  and the seventh core cavity  107 . The positions of the projected portions  203  of the pushing element  2023  respectively correspond to the positions of the cavity wall  111  between the first core cavity  101  and the second core cavity  102 , the cavity wall  111  between the third core cavity  103  and the fourth core cavity  104 , the cavity wall  111  between the fifth core cavity  105  and the sixth core cavity  106  and the cavity wall  111  between the seventh core cavity  107  and the eighth core cavity  108 . 
     The stator core winding method for the motor of the present invention will be described with the stator core having nine core cavities as an example. As shown in  FIGS. 7 and 8 , a stator core and an inserting jig are prepared initially in step  401 . The stator core includes a first core cavity, a second core cavity, a third core cavity, a fourth core cavity, a fifth core cavity, a sixth core cavity, a seventh core cavity, an eighth core cavity and a ninth core cavity. Then, in step  402 , first phase coils, for example phase A coils, are put on the strip-shaped portions of the inserting jig corresponding to the positions of the cavity wall between the first core cavity and the second core cavity and the cavity wall between the seventh core cavity and the eighth core cavity, and a second phase coil, for example a phase B coil, is put on the strip-shaped portion of the inserting jig corresponding to the position of the cavity wall between the fifth core cavity and the sixth core cavity. A third phase coil, for example a phase C coil, is put on the strip-shaped portion of the inserting jig corresponding to the position of the cavity wall between the third core cavity and the fourth core cavity. Subsequently, in step  403 , the first phase coil, for example the phase A coil, is put on the strip-shaped portion of the inserting jig corresponding to the position of the cavity wall between the fourth core cavity and the fifth core cavity, and the second phase coil, for example the phase B coil, is put on the strip-shaped portion of the inserting jig corresponding to the position of the cavity wall between the second core cavity and the third core cavity. The third phase coils, for example the phase C coils, are put on the strip-shaped portions of the inserting jig corresponding to the positions of the cavity wall between the first core cavity and the ninth core cavity and the cavity wall between the sixth core cavity and the seventh core cavity. Then, in step  404 , the second phase coil, for example the phase B coil, is put on the strip-shaped portion of the inserting jig corresponding to the position of the cavity wall between the eighth core cavity and the ninth core cavity. 
     Subsequently, in step  405 , the top of the inserting jig is placed into the stator core to render the outer surfaces of the strip-shaped portions to attach the edges of the cavity walls adjacent to the center of the stator core, and a plurality of pushing elements of the inserting jig are moved upwards to pass through the stator core, so as to push the coils of different phases into the core cavities in the stator core. Then, in step  406 , in accordance with a wiring diagram shown in  FIG. 9 , the first phase coils in the core cavities, for example the first phase coil  301 A in the first core cavity, the first phase coil  304 A in the fourth core cavity and the first phase coil  307 A in the seventh core cavity, are connected to one another for example by welding as phase A, and the second phase coils in the core cavities, for example the second phase coil  302 B in the second core cavity the second phase coil  305 B in the fifth core cavity, and the second phase coil  308 B in the eighth core cavity, are connected to one another for example by welding as phase B. The third phase coils in the core cavities, for example the third phase coil  303 C in the third core cavity the third phase coil  306 C in the sixth core cavity and the third phase coil  309 C in the ninth core cavity, are connected to one another for example by welding as phase C, and the first phase coil  302 A in the second core cavity, the first phase coil  305 A in the fifth core cavity, the first phase coil  308 A in the eighth core cavity, the second phase coil  303 B in the third core cavity, the second phase coil  306 B in the sixth core cavity, the second phase coil  309 B in the ninth core cavity, the third phase coil  304 C in the fourth core cavity, the third phase coil  307 C in the seventh core cavity and the third phase coil  301 C in the first core cavity are connected to one another for example by welding as a natural point. Finally, in step  407 , the outer shape of the coils of different phases is shaped by a shaping machine to the smallest to complete the winding procedure of the stator core of the motor. 
     In another embodiment of the present invention, the first phase coil may be phase B coil, the second phase coil may be phase C coil and the third phase coil may be phase A coil. In still another embodiment of the present invention, the first phase coil may be phase C coil, the second phase coil may be phase A coil and the third phase coil may be phase B coil. In one embodiment, the coils of different phases may be formed with a winding machine by using a concentrative inserting based winding method. 
     In one embodiment of the present invention, the completed stator core is shown in  FIG. 6 . One side of the first core cavity  101  adjacent to the center of the stator core is disposed with the first phase coil, for example phase A coil while the other side of the first core cavity  101  far from the center of the stator core is disposed with the third phase coil, for example phase C coil. One side of the second core cavity  102  adjacent to the center of the stator core is disposed with the first phase coil, for example phase A coil while the other side of the second core cavity  102  far from the center of the stator core is disposed with the second phase coil, for example phase B coil. One side of the third core cavity  103  adjacent to the center of the stator core is disposed with the third phase coil, for example phase C coil while the other side of the third core cavity  103  far from the center of the stator core is disposed with the second phase coil, for example phase B coil. One side of the fourth core cavity  104  adjacent to the center of the stator core is disposed with the third phase coil, for example phase C coil while the other side of the fourth core cavity  104  far from the center of the stator core is disposed with the first phase coil, for example phase A coil. 
     One side of the fifth core cavity  105  adjacent to the center of the stator core is disposed with the second phase coil, for example phase B coil while the other side of the fifth core cavity  105  far from the center of the stator core is disposed with the first phase coil, for example phase A coil. One side of the sixth core cavity  106  adjacent to the center of the stator core is disposed with the second phase coil, for example phase B coil while the other side of the sixth core cavity  106  far from the center of the stator core is disposed with the third phase coil, for example phase C coil. One side of the seventh core cavity  107  adjacent to the center of the stator core is disposed with the first phase coil, for example phase A coil while the other side of the seventh core cavity  107  far from the center of the stator core is disposed with the third phase coil, for example phase C coil. One side of the eighth core cavity  108  adjacent to the center of the stator core is disposed with the first phase coil, for example phase A coil while the other side of the eighth core cavity  108  far from the center of the stator core is disposed with the second phase coil, for example phase B coil. One side of the ninth core cavity  109  adjacent to the center of the stator core is disposed with the third phase coil, for example phase C coil while the other side of the ninth core cavity  109  far from the center of the stator core is disposed with the second phase coil, for example phase B coil. 
     In another embodiment of the present invention, the first phase coil may be phase B coil, the second phase coil may be phase C coil and the third phase coil may be phase A coil. In still another embodiment of the present invention, the first phase coil may be phase C coil, the second phase coil may be phase A coil and the third phase coil may be phase B coil. 
     The three phase inductances (L AB , L BC  and L CA ) of the stator core completed by the stator core winding method of the present invention can be metered by a LCR impedance meter, and the frequency of metering can be 1 KHz. In one embodiment, the three phase inductances (L AB , L BC  and L CA ) metered by the LCR impedance meter are 126.80μH, 127.50μH and 129.50μH. The inductance unbalance (L unb ) of the stator core of the motor can be calculated from the metered three phase inductances (L AB , L BC  and L CA ) by using an inductance unbalance calculating function. In one embodiment, the inductance unbalance calculating function may be as follows: 
     
       
         
           
             
               L 
               unb 
             
             = 
             
               
                 
                   1 
                   3 
                 
                 ⁢ 
                 
                   
                     ∑ 
                     
                         
                     
                   
                   ⁢ 
                   
                     
                       [ 
                       
                         
                           ( 
                           
                             
                               L 
                               i 
                             
                             - 
                             
                               L 
                               ave 
                             
                           
                           ) 
                         
                         
                           L 
                           ave 
                         
                       
                       ] 
                     
                     2 
                   
                 
               
             
           
         
       
       
         
           
             
               L 
               ave 
             
             = 
             
               
                 1 
                 3 
               
               ⁢ 
               
                 
                   ∑ 
                   
                       
                   
                 
                 ⁢ 
                 
                   L 
                   i 
                 
               
             
           
         
       
     
     wherein i=AB, BC, CA. 
     In one embodiment, after the metered three phase inductances (L AB =126.80 μH, L BC =127.50 μH and L CA =129.50 μH) are introduced into the aforementioned inductance unbalance calculating function, the inductance unbalance (L unb ) of the stator core of the motor is 0.894%, which is one third of the inductance unbalance of the stator core completed by the traditional winding method. Therefore, the stator core winding method for the motor of the present invention can greatly decrease the unbalance between the three phase inductances of the stator core of the motor so as to enhance the performance of the motor. 
     The foregoing description is a preferred embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, not for limiting, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations are included insofar as they come within the scope of the invention as claimed or the equivalents thereof.