Abstract:
The rotary machine of the present disclosure is provided with an annular stator that has: an annular yoke section; multiple salient poles that protrude radially inward and are arranged circumferentially; and coils disposed on the salient poles. Circumferential surfaces of the salient poles are formed into tapered surfaces that taper toward the tip of the salient poles, and the coils include a first coil and a second coil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation application of International Application No. PCT/JP2015/079976, filed Oct. 23, 2015, which claims priority to Japanese Patent Application No. 2014-217020, filed Oct. 24, 2014. The contents of these applications are incorporated herein by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a rotary machine and a method for manufacturing a rotary machine. 
       BACKGROUND 
       [0003]    As shown in Patent Document 1, for example, in a rotary machine such as a motor, there is a case in which a salient pole whose circumferential surface is a tapered surface that is tapered toward a tip is employed. By using such a shape of the salient pole, magnetic saturation can be suppressed and degradation of motor efficiency can be suppressed even at the time of high power output. Also, Patent Document 2 discloses that, in a stator of a motor, a coil is formed by edgewise bending and spirally winding of a flat type conductor having a rectangular cross section molded from an element wire, and the flat type conductor is molded into a stepped shape in advance so that lengths of a long side and a short side of the rectangular cross section are different for each turn when it is wound. By having such a shape, the coil space factor of a first coil and a second coil with respect to a slot can be increased. In addition, background art is disclosed also in Patent Documents 3 to 4. 
       DOCUMENTS OF THE RELATED ART 
     Patent Document 
       [0004]    [Patent Document 1]
       PCT International Publication No. WO 2012/137302       
 
         [0006]    [Patent Document 2]
       Japanese Unexamined Patent Application, First Publication No. 2008-167593       
 
         [0008]    [Patent Document 3]
       Japanese Unexamined Patent Application, First Publication No. H11-032457       
 
         [0010]    [Patent Document 4]
       Japanese Unexamined Patent Application, First Publication No. 2000-041365       
 
         [0012]    [Patent Document 5]
       Japanese Unexamined Patent Application, First Publication No. H09-308142       
 
       SUMMARY 
       [0014]    Coils can be provided in a single stator. Normally, these coils have the same shape. When the coils are used to maximize the space factor, generally, such a same shaped coil can be provided to be in contact with an adjacent coil. 
         [0015]    However, when coils of the same shape are provided on salient poles which protrude toward a radial inner side of the stator, whose circumferential surface is a tapered surface, a dead space in which there is no winding between the salient poles is generated. More specifically, in assembling the stator, when the coils that have been molded are sequentially mounted on the salient poles provided in a circumferential direction, a coil is mounted on each of the salient poles along each central axis of the salient poles facing a radial direction of the stator. At this time, to prevent an end portion of an outer circumferential surface of a previously mounted coil close to an inner side of the stator from interfering with an end portion of an outer circumferential surface of a subsequently mounted coil close to an outer side of the stator, it is necessary to reduce a diameter of the end portion of the coil close to the outer side of the stator. As a result, a dead space is generated between adjacent coils. 
         [0016]    The present disclosure is made in consideration of the above-described problems and directed to improve the performance of a rotary machine in which a stator having salient poles protruding toward the radial inner side is provided by improving the coil space factor. 
         [0017]    To achieve the above-described objects, a first aspect of the present disclosure is a rotary machine including an annular stator having an annular yoke portion, salient poles protruding toward a radial inner side and arranged in a circumferential direction, and a coil provided on the salient poles, wherein a circumferential surface of each of the salient poles is a tapered surface tapered toward a tip of the salient pole. The coil includes a first coil having an inner circumferential surface inclined along the tapered surface of the salient pole and an outer circumferential surface inclined toward the radial inner side of the stator and a second coil provided on the salient pole adjacent to the salient pole on which the first coil is provided and having an inner circumferential surface inclined along the tapered surface of the salient pole and an outer circumferential surface inclined toward a radial outer side of the stator. 
         [0018]    A second aspect of the present disclosure is a method of manufacturing a rotary machine including an annular stator having an annular yoke portion, salient poles protruding toward a radial inner side and arranged in a circumferential direction, and a coil provided on the salient poles, wherein a circumferential surface of each of the salient poles is a tapered surface tapered toward a tip of the salient pole, and wherein the coil includes a first coil having an inner circumferential surface inclined along the tapered surface of the salient pole and an outer circumferential surface inclined toward the radial inner side of the stator and a second coil provided on the salient pole adjacent to the salient pole on which the first coil is provided and having an inner circumferential surface inclined along the tapered surface of the salient pole and an outer circumferential surface inclined toward a radial outer side of the stator. This method of manufacturing the rotary machine includes a winding process in which the first coil and the second coil are molded by winding the windings multiple times, a press process in which the coils molded in the winding process are compression-molded, and an assembly process in which the coils compression-molded in the press process are mounted on the salient poles. 
         [0019]    According to a rotary machine of the present disclosure, a coil includes a first coil having an inner circumferential surface inclined along a tapered surface of each salient pole and an outer circumferential surface inclined toward a radial inner side of a stator and a second coil having an inner circumferential surface inclined along the tapered surface of the salient pole and an outer circumferential surface inclined toward a radial outer side of the stator. Also, the first coil and the second coil are alternately provided on the salient poles in a circumferential direction of the stator. According to the rotary machine described above, when the first coil is mounted on each of the salient poles in advance, since an outer circumferential surface of the first coil is inclined toward the radial outer side of the stator, an end portion of the outer circumferential surface of the first coil close to the inner side of the stator is disposed close to the salient pole. Thus, it is possible to prevent the end portion of the outer circumferential surface of the first coil close to the inner side of the stator from disturbing the mounting of the second coil. In addition, since the second coil has an outer circumferential surface which is inclined so as to face the radial outer side of the stator, an end portion of the outer circumferential surface close to the inner side of the stator becomes more distant from the salient pole. Thus, since the outer circumferential surface of the second coil can be come close to or brought into contact with the outer circumferential surface of the first coil, the coil space factor can be improved. According to the present disclosure described above, by alternately providing two coils with different shapes on the salient poles, all the coils can be mounted on the salient poles and improvement in the coil space factor is realized. According to the present disclosure described above, it is possible to increase the performance of a rotary machine in which a stator having salient poles protruding toward a radial inner side is provided by improving the coil space factor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a cross-sectional view of a switched reluctance motor according to one embodiment of the present disclosure. 
           [0021]      FIG. 2  is a partially enlarged cross-sectional view of a switched reluctance motor according to one embodiment of the present disclosure. 
           [0022]      FIG. 3  is a flowchart showing a method of manufacturing a switched reluctance motor according to one embodiment of the present disclosure. 
           [0023]      FIG. 4  is a cross-sectional view showing a process of manufacturing a switched reluctance motor according to one embodiment of the present disclosure. 
           [0024]      FIG. 5  is a cross-sectional view showing a process of manufacturing a switched reluctance motor according to one embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Hereinafter, one embodiment of a rotary machine according to the present disclosure will be described with reference to the drawings. Also, in the following embodiments, an example in which the rotary machine of the present disclosure is applied to a switched reluctance motor will be described. 
         [0026]      FIG. 1  is a cross-sectional view of a switched reluctance motor  1  of the present embodiment. As shown in  FIG. 1 , the switched reluctance motor  1  of the present embodiment includes a rotor  2  and a stator  3 . Although not shown in  FIG. 1 , the switched reluctance motor  1  of the present embodiment includes necessary components such as a casing, a shaft, a control circuit, and the like. 
         [0027]    The rotor  2  has an annular shape centered on a rotor shaft L and is rotatably supported about the rotor shaft L by bearings or the like that are not shown. The rotor  2  includes an annular yoke portion  2   a  and salient poles  2   b  which protrude from the yoke portion  2   a  toward an outer side of the rotor  2 . The yoke portion  2   a  and salient poles  2   b  are formed by fastening electromagnetic steel sheets stacked in a direction along the rotor shaft L using any one method of press-fitting, shrinkage-fitting, or bolting (not shown). The salient poles  2   b  protrude from an outer circumferential surface of the yoke portion  2   a  toward the stator  3  and the salient poles  2   b  are provided at regular intervals in a circumferential direction of the rotor  2 . In addition, in the present embodiment, six salient poles  2   b  are provided at intervals of 60° as shown in  FIG. 1 . 
         [0028]    The stator  3  is disposed on the outside of the rotor  2  and has an annular shape centered on the rotor shaft L to surround the rotor  2  from a radial outer side. Such a stator  3  includes an annular yoke portion  3   a  and salient poles  3   b  which protrude from the yoke portion  3   a  toward an inner side of the stator  3 . The yoke portion  3   a  and salient poles  3   b  are integrally formed of a magnetic material. In addition, the stator  3  includes a first coil  3   c  and a second coil  3   d  wound around the salient poles  3   b.    
         [0029]    Each of the salient poles  3   b  protrudes from an inner circumferential surface of the yoke portion  3   a  toward the rotor  2  and includes a circumferential surface tapered toward a tip. That is, the salient pole  3   b  has a tapered surface  3   b   1  tapered toward the tip. Also, the salient poles  3   b  are provided at regular intervals in a circumferential direction of the stator  3 . In the present embodiment, eight salient poles  3   b  are provided at intervals of 45° as shown in  FIG. 1 . 
         [0030]      FIG. 2  is an enlarged view of the stator  3 . As shown in  FIG. 2 , the first coil  3   c  includes an inner circumferential surface  3   c   1  inclined along the tapered surface  3   b   1  of each of the salient poles  3   b  and an outer circumferential surface  3   c   2  inclined toward a radial outer side of the stator  3 . Also, the first coil  3   c  is constituted by a winding (element wire) that is densely wound multiple times. The winding which constitutes this first coil  3   c  is regularly wound so that each turn of the winding along the tapered surface  3   b   1  of the salient pole  3   b  is in close contact with each other and each turn of the winding along the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not formed is in close contact with each other. However, since the first coil  3   c  is molded by further compressing the winding that has been wound and molded into a shape close to the first coil  3   c,  the “each turn of the winding along the tapered surface  3   b   1  of the salient pole  3   b  is in close contact with each other” also includes each turn of the winding being in close contact with each other with a slight deviation from the direction along the tapered surface  3   b   1  and the “each turn of the winding along the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not formed is in close contact with each other” also includes each turn of the winding being in close contact with each other with a slight deviation from a direction along the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not formed. Here, the inner circumferential surface  3   c   1  and the outer circumferential surface  3   c   2  refer to an inner circumferential surface and an outer circumferential surface of the molded body obtained by finally molding the winding into the shape of the first coil  3   c.  The inner circumferential surface  3   c   1  and the outer circumferential surface  3   c   2  described as above are determined in advance at a design stage and are formed according to the design. 
         [0031]    Such a first coil  3   c  has an inner diameter in which the inner circumferential surface  3   c   1  is in contact with the tapered surface  3   b   1  of the salient pole  3   b.  Here, the inner circumferential surface  3   c   1  is inclined along the tapered surface  3   b   1  of the salient pole  3   b.  Thus, as shown in  FIG. 2 , the inner circumferential surface  3   c   1  of the first coil  3   c  is in surface contact with the tapered surface  3   b   1  of the salient pole  3   b.    
         [0032]    Also, the first coil  3   c  is inclined such that the outer circumferential surface  3   c   2  faces the radial outer side of the stator  3  when a radial direction of the stator  3  passing through the outer circumferential surface  3   c   2  is taken as a reference. Therefore, an end portion of the outer circumferential surface  3   c   2  close to the inner side of the stator  3  (an end portion of an upper side of the first coil  3   c  in  FIG. 2 ) is disposed close to the salient pole  3   b  on which the first coil  3   c  is provided when compared to a case in which the outer circumferential surface is formed along the radial direction of the stator  3  or in parallel with a central axis of the salient pole  3   b.    
         [0033]    The second coil  3   d  is provided on a salient pole  3   b  adjacent to the salient pole  3   b  on which the first coil  3   c  is provided, and includes an inner circumferential surface  3   d   1  inclined along a tapered surface  3   b   1  of the salient pole  3   b  and an outer circumferential surface  3   d   2  inclined toward a radial inner side of the stator  3 . In addition, as in the first coil  3   c,  the second coil  3   d  also is constituted by a winding (element wire) that is densely wound multiple times. The winding constituting this second coil  3   d  is regularly wound so that each turn of the winding along the tapered surface  3   b   1  of the salient pole  3   b  is in close contact with each other and each turn of the winding along the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not formed is in close contact with each other. However, since the second coil  3   d  is molded by further compressing the winding that has been wound and molded into a shape close to the second coil  3   d,  the “each turn of the winding along the tapered surface  3   b   1  of the salient pole  3   b  is in close contact with each other” also includes each turn of the winding being in close contact with each other with a slight deviation from the direction along the tapered surface  3   b   1  and the “each turn of the winding along the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not foil led is in close contact with each other” also includes each turn of the windings being in close contact with each other with a slight deviation from a direction along the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not formed. Here, the inner circumferential surface  3   d   1  and the outer circumferential surface  3   d   2  refer to an inner circumferential surface and an outer circumferential surface of the molded body obtained by finally molding the winding into the shape of the second coil  3   d.  The inner circumferential surface  3   d   1  and the outer circumferential surface  3   d   2  described as above are determined in advance at a design stage and are formed according to the design. 
         [0034]    Such a second coil  3   d  has an inner diameter in which the inner circumferential surface  3   d   1  is in contact with the tapered surface  3   b   1  of the salient pole  3   b.  Here, the inner circumferential surface  3   c   1  is inclined along the tapered surface  3   b   1  of the salient pole  3   b.  Thus, as shown in  FIG. 2 , the inner circumferential surface  3   d   1  of the second coil  3   d  is in surface contact with the tapered surface  3   b   1  of the salient pole  3   b.    
         [0035]    Also, the second coil  3   d  is inclined such that the outer circumferential surface  3   d   2  faces the radial inner side of the stator  3  when the radial direction of the stator  3  passing through the outer circumferential surface  3   d   2  is taken as a reference. Therefore, an end portion of the outer circumferential surface  3   d   2  close to the inner side of the stator  3  (an end portion of the upper side of the second coil  3   d  in  FIG. 2 ) is disposed to become more distant from the salient pole  3   b  on which the second coil  3   d  is provided when compared to a case in which the outer circumferential surface is formed along the radial direction of the stator  3  or in parallel with the central axis of the salient pole  3   b.    
         [0036]    Also, in the present embodiment, an inclination angle formed by a reference line along the radial direction of the stator  3  and the outer circumferential surface  3   c   2  of the first coil  3   c  inclined so as to face the inner side of the stator  3  and an inclination angle formed by the radial direction of the stator  3  (the reference line) and the outer circumferential surface  3   d   2  of the second coil  3   d  inclined so as to face the outer side of the stator  3  are set to be the same. In addition, an outer diameter of the first coil  3   c  and an outer diameter of the second coil  3   d  are set so that the outer circumferential surface  3   c   2  and the outer circumferential surface  3   d   2  are in surface contact with each other. Thus, the outer circumferential surface  3   c   2  of the first coil  3   c  is in surface contact with the outer circumferential surface  3   d   2  of the second coil  3   d  in the entire region in the radial direction of the stator  3  at a position in which they are in contact with each other. 
         [0037]    Also, a diameter of the first coil  3   c  and a diameter of the second coil  3   d  are set so that a cross-sectional area of a cross section perpendicular to the winding direction of the winding of the first coil  3   c  (a cross section shown in  FIG. 2 ) and a cross-sectional area of a cross section perpendicular to the winding direction of the winding of the second coil  3   d  (a cross section shown in  FIG. 2 ) are the same. When it is assumed that the inner and outer side surfaces of the stator  3  at the first coil  3   c  and the second coil  3   d  are planar, a shape of the above-described cross sections of the first coil  3   c  and the second coil  3   d  is trapezoidal as shown in  FIG. 2 . 
         [0038]    Next, a method of manufacturing such a switched reluctance motor  1  of the present embodiment will be described with reference to  FIGS. 3 to 5 .  FIG. 3  is a flowchart schematically showing a process of manufacturing the switched reluctance motor  1  of the present embodiment. In addition, in the following description, it is assumed that the rotor  2  and an integrally molded body of the yoke portion  3   a  and the salient pole  3   b  of the stator  3  have already been formed. 
         [0039]    First, as shown in  FIG. 3 , a winding process (Step S 1 ) is performed. In this step, the first coil  3   c  and the second coil  3   d  are molded by winding the winding multiple times. Specifically, the first coil  3   c  and the second coil  3   d  are molded by regularly winding the winding so that, assuming the tapered surface  3   b   1  of the salient pole  3   b , each turn of the winding along the tapered surface is in close contact with each other and, assuming the inner circumferential surface of the yoke portion  3   a  in which the salient pole  3   b  is not formed, each turn of the winding along the inner circumferential surface is in close contact with each other. Here, the first coil  3   c  and the second coil  3   d  are molded such that sizes thereof are larger than the final sizes. In addition, when a large current is used in the switched reluctance motor  1 , it is suitable to reduce copper loss by increasing a cross-sectional area of a body portion of the winding to reduce a resistance value of the switched reluctance motor  1 . Thus, in the winding process S 1 , the winding may not be wound by a single wire, but may be wound by a state in which two or more wires are bundled (in parallel). Next, a press process (Step S 2 ) is performed as shown in  FIG. 3 . In this step, the first coil  3   c  and the second coil  3   d  which have been molded in the winding process S 1  are compression-molded by press processing using a die. Thereby, winding densities of the first coil  3   c  and the second coil  3   d  are increased and the first coil  3   c  and the second coil  3   d  are molded into the final shapes and sizes. 
         [0040]    Next, an assembly process (Step S 3 ) is performed as shown in  FIG. 3 . In this step, the first coil  3   c  and the second coil  3   d  compression-molded by the press process S 2  are mounted on the salient poles  3   b  of the stator  3 . First, the first coil  3   c  is mounted on every other one of the salient poles  3   b  disposed in a circumferential direction of the stator  3  as shown in  FIG. 4 , and then, the second coil  3   d  is mounted on salient poles  3   b  on which the first coil  3   c  has not been mounted as shown in  FIG. 5 . After this, the rotor  2  and the like can be assembled. 
         [0041]    According to the present embodiment described above, the switched reluctance motor  1  includes the first coil  3   c  having the inner circumferential surface  3   c   1  inclined along the tapered surface  3   b   1  of the salient poles  3   b  and the outer circumferential surface  3   c   2  inclined toward the radial outer side of the stator  3 , and the second coil  3   d  having the inner circumferential surface  3   d   1  inclined along the tapered surface  3   b   1  of the salient poles  3   b  and the outer circumferential surface  3   d   2  inclined toward the radial inner side of the stator  3 . Also, the first coil  3   c  and the second coil  3   d  are alternately provided at the salient poles  3   b  disposed in the circumferential direction of the stator  3 . 
         [0042]    According to the switched reluctance motor  1  of the present embodiment described above, as shown in  FIG. 4 , when the first coil  3   c  is mounted on each of the salient poles  3   b  first, since the outer circumferential surface  3   c   2  of the first coil  3   c  is inclined toward the radial outer side of the stator  3 , the end portion of the outer circumferential surface  3   c   2  of the first coil  3   c  close to the inner side of the stator  3  is disposed close to the salient pole  3   b.  Thus, as shown in  FIG. 5 , it is possible to prevent the end portion of the outer circumferential surface  3   c   2  of the first coil  3   c  close to the inner side of the stator  3  from disturbing the mounting of the second coil  3   d.    
         [0043]    In addition, since the second coil  3   d  has the outer circumferential surface  3   d   2  which is inclined so as to face the radial outer side of the stator  3 , the end portion of the outer circumferential surface  3   d   2  close to the inner side of the stator  3  becomes more distant from the salient pole  3   b.  Thus, the outer circumferential surface  3   d   2  of the second coil  3   d  can be brought into contact with the outer circumferential surface  3   c   2  of the first coil  3   c,  and thereby the coil space factor can be improved. 
         [0044]    According to the switched reluctance motor  1  of the present embodiment described above, by alternately providing two coils with different shapes on the salient poles, all the coils can be mounted on the salient poles  2   b  and improvement in the coil space factor is realized. According to the switched reluctance motor  1  of the present embodiment described above, it is possible to improve the performance by improving the coil space factor. 
         [0045]    Also, in the switched reluctance motor  1  of the present embodiment, the outer circumferential surface  3   c   2  of the first coil  3   c  is in contact with the outer circumferential surface  3   d   2  of the second coil  3   d  in the entire region in the radial direction of the stator  3  at a position in which they are in contact with each other. Therefore, it is possible to maximize the coil space factor. 
         [0046]    Also, in the switched reluctance motor  1  of the present embodiment, the cross-sectional area of the cross section perpendicular to the winding direction of the winding of the first coil  3   c  (a cross section shown in  FIG. 2 ) and the cross-sectional area of the cross section perpendicular to the winding direction of the winding of the second coil  3   d  (a cross section shown in  FIG. 2 ) are set to be the same. Therefore, since magnetic flux density formed by the first coil  3   c  and magnetic flux density formed by the second coil  3   d  can be the same, it is possible to effectively reduce torque ripple or the like. 
         [0047]    Also, in the switched reluctance motor  1  of the present embodiment, the above-described cross sections of the first coil  3   c  and a second coil  3   d  have a trapezoidal shape as shown in  FIG. 2 . For example, it may be possible for the above-described cross sections of the first coil  3   c  and the second coil  3   d  to have a triangular shape, but in such a case, the top portion of the triangle is pointed at an acute angle. Thus, there is a possibility that the first coil  3   c  and a second coil  3   d  are likely to structurally collapse. On the other hand, when the cross section of the first coil  3   c  and the second coil  3   d  has a trapezoidal shape as described above, the first coil  3   c  and the second coil  3   d  have high strength and cannot easily collapse. 
         [0048]    Also, the present disclosure is not limited to the above-described embodiment, and for example, the following modified examples can be considered. In the above-described embodiment, an example in which the present disclosure is applied to the switched reluctance motor  1  has been described, but the present disclosure is not limited thereto. For example, it is possible to apply the present disclosure to permanent magnet (PM) motors. Also, it is also possible to apply this disclosure to other rotary machines such as an electric generator. 
       INDUSTRIAL APPLICABILITY 
       [0049]    According to the present disclosure, it is possible to improve the performance of a rotary machine in which a stator having salient poles protruding toward an inner side is provided by improving the coil space factor.