Abstract:
The present invention relates to a magnetic gear type electric rotating machine. Specifically, the purpose is to provide a magnetic gear type electric rotating machine with which the intensity of a permanent magnetic field can be improved without increasing material and manufacturing costs, and deterioration of torque transmission characteristics can be prevented. To this end, in the present invention, concave and convex sections are provided on a surface of at least one of cores ( 12, 22 ) for a first permanent magnetic field ( 1 ) and a second permanent magnetic field ( 2 ). The convex sections ( 13 ) are arranged along the circumferential direction at the center sections of permanent magnetic poles ( 11   a   , 11   b ), and the concave sections ( 14 ) are arranged along the circumferential direction at the edge sections of the permanent magnetic poles ( 11   a   , 11   b ).

Description:
TECHNICAL FIELD 
     The present invention relates to a magnetic gear-type electric rotating machine. 
     BACKGROUND ART 
     In recent years, a magnetic flux modulated type magnetic gear, in which a high torque density is realized by using a rare-earth magnet, has been studied and developed (Non-PTL 1). PTL 1 discloses a magnetic gear-type electric rotating machine in which a magnetic gear and a winding type stator are integrated, and more specifically, an improvement of intensity of a permanent magnet field system. 
     Furthermore, in Non-PTL 2, a configuration in which a permanent magnet is divided in a direction of stack length in a magnetic gear mechanism is disclosed. In Non-PTL 3, a configuration in which an interior permanent magnet is used in a rotor structure of a magnetic gear mechanism is disclosed. 
     CITATION LIST 
     Patent Literature 
     PTL 1: WO2009/130456 
     Non-Patent Literature 
     Non-PTL 1: K. Atallah and D. Howe: A Novel High-Performance Magnetic Gear: IEEE Transactions on Magnetics, VoL. 37, No. 4, pp. 2844-2846 
     Non-PTL 2: Journal of the Magnetics Society of Japan Vol. 33, No. 2, 2009 “A Way to Improve Efficiency of Permanent-Magnet Magnetic Gears” 
     Non-PTL 3: Journal of the Magnetic Society of Japan Vol. 34, No. 3, 2010 “Consideration of Rotor Structure in Permanent-Magnet Magnetic Gears” 
     SUMMARY OF INVENTION 
     Technical Problem 
     The above-described Non-PTL 1 discloses a principle and magnetic characteristics of a magnetic gear, but a mechanism and intensity thereof is not considered. 
     On the other hand, in the above-described PTL 1, a permanent magnet field system existing between a winding type stator and a pole piece is constituted by affixing a permanent magnet on both front and back surfaces of a high intensity magnetic material to improve the intensity thereof. However, affixing a permanent magnet on both surfaces increases the number of permanent magnets required, which leads to increased material and manufacturing costs. Furthermore, in a case where the permanent magnet field system is rotated at a high speed, in order to prevent scattering of a permanent magnet affixed outside due to a centrifugal force, it is necessary to add an anti-scattering member to an outer periphery portion of the permanent magnet, and as a result, a magnetic gap is increased, a magnetic resistance is increased, and a torque transmission characteristic is decreased. 
     Note that in the above-described Non-PTLs 2 and 3, a loss due to an eddy current in a magnetic gear and the like are considered, but a mechanism and intensity thereof are not considered. 
     The present invention has been made in view of the above-described problem, and an object thereof is to provide a magnetic gear-type electric rotating machine with which the intensity of a permanent magnet field system can be improved and a decrease of the torque transmission characteristics can be prevented without increasing the material and manufacturing costs. 
     Solution to Problem 
     In order to solve the above problem, for example, in a magnetic gear-type electric rotating machine including: a first permanent magnet field system having a plurality of permanent magnet magnetic poles and a core supporting the permanent magnet magnetic pole; a second permanent magnet field system having a plurality of permanent magnet magnetic poles, the number of poles thereof being different from that of the first permanent magnet field system, and a core supporting the permanent magnet magnetic pole; a modulation magnetic pole provided between the first permanent magnet field system and the second permanent magnet field system, and configured to modulate the number of poles of the first and second permanent magnet field systems by having a plurality of pole pieces; and a winding type stator having a plurality of windings interacting with the first permanent magnet field system, a recess and a projection may be provided on a surface of a core of at least one of the first permanent magnet field system or the second permanent magnet field system. 
     In order to prevent a short circuit of a permanent magnet magnetic flux, with respect to the recess and the projection provided on the surface of the core, it is preferred that the projection portion be provided at a central part of the permanent magnet magnetic pole in a circumferential direction, and the recess portion be provided at an edge of the permanent magnet magnetic pole in the circumferential direction. 
     The core of the first permanent magnet field system may be provided between the permanent magnet magnetic pole of the first permanent magnet field system and the pole pieces or between the permanent magnet magnetic pole of the first permanent magnet field system and the winding type stator. 
     With respect to the recess and the projection provided on the surface of the core, the projection portion may be configured to be a curved or plane surface. 
     The core, having the recess and the projection on a surface thereof, may be formed by cutting a tape-like magnetic material thin plate into a recess and projection shape and by bending the recess portion of the magnetic material thin plate, which has been cut. 
     Furthermore, the recess and the projection may be provided on a surface of the permanent magnet magnetic pole of at least one of the first permanent magnet field system or the second permanent magnet field system. 
     Advantageous Effects of Invention 
     According to an embodiment of the present invention, it is possible to improve intensity of a permanent magnet field system while decreasing material and manufacturing costs of a magnetic gear-type electric rotating machine. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view illustrating a magnetic gear-type electric rotating machine of Example 1 according to the present invention. 
         FIG. 2  is an external view illustrating a first permanent magnet field system of Example 2 according to the present invention. 
         FIG. 3  is a sectional view illustrating a magnetic gear-type electric rotating machine of Example 3 according to the present invention (part 1). 
         FIG. 4  is a view illustrating a recess and a projection on a surface of a core of Example 3 according to the present invention. 
         FIG. 5  is a sectional view illustrating a magnetic gear-type electric rotating machine of Example 3 according to the present invention (part 2). 
         FIG. 6  is a view illustrating a method of manufacturing a core of a first permanent magnet field system of Example 4 according to the present invention. 
         FIG. 7  is a sectional view illustrating a magnetic gear-type electric rotating machine of Example 5 according to the present invention. 
         FIG. 8  is a sectional view illustrating a magnetic gear-type electric rotating machine of Example 6 according to the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of a magnetic gear-type electric rotating machine according to the present invention are described with reference to  FIGS. 1 to 7 . Note that in the following embodiments, a radial gap type is used in descriptions; however, these embodiments can also be realized in the same way by using other types (e.g., axial gap type, linear type, etc.). 
     Example 1 
     Hereinafter, a first Example according to the present invention is described using  FIG. 1 .  FIG. 1  is a sectional view of a magnetic gear-type electric rotating machine according to the first Example of the present invention. 
     The magnetic gear-type electric rotating machine includes: a first permanent magnet field system  1  having a plurality of permanent magnet magnetic poles; a second permanent magnet field system  2  having a plurality of permanent magnet magnetic poles, the number of poles thereof being different from that of the first permanent magnet field system  1 ; a modulation magnetic pole  3  having a plurality of pole pieces; and a winding type stator  4  having a plurality of windings that interacts with the first permanent magnet field system. In a case where the modulation magnetic pole  3  is fixed in addition to the winding type stator  4 , the first permanent magnet field system  1  rotates in synchronization with a rotation field system formed by the winding type stator  4 , and the second permanent magnet field system  2  rotates at a speed determined by a gear ratio. In a case where the second permanent magnet field system  2  is fixed in addition to the winding type stator  4 , the first permanent magnet field system  1  rotates in synchronization with the rotation field system formed by the winding type stator  4 , and the modulation magnetic pole  3  rotates at a speed determined by a gear ratio. 
     The first permanent magnet field system  1  has a plurality of permanent magnet magnetic poles  11   a  and  11   b  alternately disposed in a circumferential direction, and has a core  12  on an outer periphery side thereof. Here, the permanent magnet magnetic poles  11   a  and  11   b  have a polarity different from each other. The second permanent magnet field system  2  has a plurality of permanent magnet magnetic poles  21   a  and  21   b  alternately disposed in the circumferential direction, the number of poles thereof being different from that of the first permanent magnet field system  1 , and has a core  22  on an outer periphery side thereof. Here, the permanent magnet magnetic poles  21   a  and  21   b  have a polarity different from each other. The modulation magnetic pole  3  includes a plurality of pole pieces  31 , the number thereof being a sum of the number of pole pairs of the first permanent magnet field system  1  and the number of pole pairs of the second permanent magnet field system, and a non-magnetic case  32 , which includes the pole pieces  31 . The modulation magnetic pole  3  is disposed between the first permanent magnet field system  1  and the second permanent magnet field system  2 . The winding type stator  4  includes a core  41  having a plurality of teeth and a winding  42  forming a rotation field system, and is disposed in an innermost periphery portion. 
     A material of the core  12  of the first permanent magnet field system  1 , the core  22  of the second permanent magnet field system  2 , the pole pieces  31 , and the core  41  of the winding type stator includes a soft magnetic material such as electrical steel, a dust core, an amorphous metal, or permendur. To prevent an eddy current due to a magnetic flux change, when the electrical steel or the like is used, it is configured by layering thin plates. A material of the non-magnetic case  32  includes a resin mold, a fiber reinforced plastic (FRP), a carbon fiber, a glass fiber, or the like. 
     In this Example, the core  12  of the first permanent magnet field system  1  is provided between the permanent magnet magnetic poles  11   a  and  11   b  of the first permanent magnet field system  1  and the modulation magnetic pole  3 . Therefore, in a case where the first permanent magnet field system  1  is rotated at a high speed, scattering caused by a centrifugal force applied to the permanent magnets  11   a  and  11   b  can be prevented by the core  12 , and the intensity of the first permanent magnet field system  1  can be increased. Furthermore, since the permanent magnet magnetic poles  11   a  and  11   b  are near the winding type stator  4 , it is possible to increase a torque acting between the winding type stator  4  and the first permanent magnet field system  1 . 
     A recess and a projection are provided on a surface of the core  12  of the first permanent magnet field system  1 , a projection portion  13  is disposed at a central part in the circumferential direction of the permanent magnet magnetic poles  11   a  and  11   b , and a recess portion  14  is disposed at an edge in the circumferential direction of the permanent magnet magnetic poles  11   a  and  11   b . That is, an outer peripheral surface of the permanent magnet magnetic pole  11   a  and the permanent magnet magnetic pole  11   b  forms a cylindrical shape having a radius r1 with a center thereof at a point O, and a thickness d of the core  12  changes along the circumferential direction of this cylindrical surface. The thickness d of the core  12  becomes thick at the projection portion  13  and becomes thin at the recess portion  14 . Therefore, the thickness d of the core  12  is large at the central part of the permanent magnet magnetic poles  11   a  and  11   b  in the circumferential direction, and the thickness d of the core  12  is small at the edge of the permanent magnet magnetic poles  11   a  and  11   b  in the circumferential direction. Using the outer peripheral surface of the permanent magnet magnetic poles  11   a  and  11   b  as a standard, the projection portion  13  is formed by the thickness d of the core  12  becoming large, and the recess portion  14  is formed by the thickness d of the core  12  becoming small. Note that the thickness d of the core  12  is defined by a width dimension in a diameter direction (a length d of a section in which a line segment extending in the diameter direction and passing through the center O of the electric rotating machine crosses with the core  12 ). In the below described each Example, in the same way as this Example, the recess and the projection formed on the surface of the core or the permanent magnet magnetic pole are defined by a dimension in the diameter direction (the length d of a section in which a line segment extending in the diameter direction and passing through the center O of the electric rotating machine crosses with the core  12 ). Accordingly, it is possible to prevent a short circuit of the magnetic flux occurring between the permanent magnet magnetic poles  11   a  and  11   b , and to prevent a decrease in the effective magnetic flux interacting with the second permanent magnet field system  2 . 
     Furthermore, the recess and the projection may also be provided on an outer peripheral surface of the core  22  of the second permanent magnet field system  2 , and by providing the recess and the projection on the surface thereof, it is possible to increase a surface area per the same body, whereby radiation and cooling effects can be increased. 
     Example 2 
     Then, a second Example according to the present invention is described by using  FIG. 2 . Note that in this Example, the second permanent magnet field system  2 , the modulation magnetic pole  3 , and the winding type stator  4  are omitted because these are the same as those in  FIG. 1 , and only a first permanent magnet field system  1   a  is illustrated. 
     In this Example, a core  12   a  of the first permanent magnet field system  1   a  is layered by shifting in a circumferential direction centering on a rotational shaft, and a row of a recess and a projection provided on a surface of the core  12   a  is configured to be skewed relative to the rotational shaft. Then, by the recess and the projection on the core surface rotating, air between the first permanent magnet field system  1   a  and the modulation magnetic pole  3  is flowed in an axial direction, whereby a radiation effect of the magnetic gear-type electric rotating machine can be increased. Furthermore, by using a so-called skew configuration, a cogging torque and a torque ripple occurring between the first permanent magnet field system  1   a  and the modulation magnetic pole  3  can be decreased. 
     Note that, as illustrated in  FIG. 2 , the skew may have a certain angle relative to the axial direction, or may be turned back in a V-shape at a central part in the axial direction. In a case where the skew has a certain angle relative to the axial direction, a force is also generated in the axial direction, but in a case where the skew is turned back in a V-shape, the force in the axial direction can be cancelled, and a load on a bearing can be decreased. 
     Example 3 
     Then, a third Example according to the present invention is described by using  FIGS. 3 to 5 .  FIG. 3  is a sectional view of a magnetic gear-type electric rotating machine according to the third Example of the present invention. It is different from  FIG. 1  in that the first permanent magnet field system  1  is replaced with a first permanent magnet field system  1   b.    
     In this Example, a core  12   b  of the first permanent magnet field system  1   b  is provided between the permanent magnet magnetic poles  11   a  and  11   b  of the first permanent magnet field system  1   b  and the winding type stator  4 . Since the permanent magnet magnetic poles  11   a  and  11   b  are near the modulation magnetic pole  3 , it is possible to increase torque acting between the first permanent magnet field system  1   b  and the second permanent magnet field system  2 . Furthermore, since a surface of the core  12   b  of the first permanent magnet field system  1   b  is on an inner periphery side, a recess and a projection on the surface of the core  12   b  are provided on the inner periphery side. That is, an inner peripheral surface of the permanent magnet magnetic pole  11   a  and the permanent magnet magnetic pole  11   b  forms a cylindrical shape having a radius r3 and centering on a point O, which is a rotation center, and a thickness d of the core  12   b  changes along a circumferential direction of this cylindrical surface. The thickness d of the core  12   b  becomes thick at the projection portion  13 , and becomes thin at the recess portion  14 . Therefore, the thickness d of the core  12   b  is large at a central part in a circumferential direction of the permanent magnet magnetic poles  11   a  and  11   b , and the thickness d of the core  12   b  is small at an edge in the circumferential direction of the permanent magnet magnetic poles  11   a  and  11   b.    
     The core  12   b  includes a plurality of planer sections  12   b   1  to  12   b   8 , which are divided such that an inner peripheral surface side thereof is bended for each of the permanent magnet magnetic poles  11   a  and  11   b  (configured as a plurality of linear sections in a cross section in  FIG. 3 ). A projection portion  13 , which is relatively projected against a cylindrical surface (circle)  12   ci , is formed in a part where a space in a radius direction becomes small between a cylindrical surface (circle)  12   ci , which has a center thereof at the rotation center O and a fixed radius, and the planer sections  12   b   1  to  12   b   8 , and a recess portion  14 , which is relatively recessed against the cylindrical surface (circle)  12   ci , is formed in a part where the space in the radius direction becomes large. 
     In this Example, with respect to the recess and the projection provided on the surface of the core  12   b  of the first permanent magnet field system, a part equivalent to the projection portion is configured to be a plane surface, and a description for this is given using  FIG. 4 . 
     A figure at the top in  FIG. 4  illustrates a part of the core  12   b  of the first permanent magnet field system. Assuming that arc-shaped permanent magnets  11   a  and  11   b  are opened linearly, the projection portion  13  and the recess portion  14  of the core  12   b  of the permanent magnet field system appear as a figure at the bottom in  FIG. 4 . Since in this way, the projection portion  13  of the core of the first permanent magnet field system is provided at the central part in the circumferential direction of the permanent magnet magnetic poles  11   a  and  11   b , and the recess portion  14  is provided at an edge in the circumferential direction of the permanent magnet magnetic poles  11   a  and  11   b , it is possible to prevent a short circuit of a magnetic flux occurring between the permanent magnet magnetic poles  11   a  and  11   b  and to prevent a decrease of an effective magnetic flux, which interacts with the winding type stator  4 . 
     In  FIG. 3 , an Example has been illustrated in which the winding type stator  4  is disposed in an innermost periphery portion, and the first permanent magnet field system  1 , the modulation magnetic pole  3 , and the second permanent magnet field system  2  are disposed in an outer periphery portion in order; however, it is also possible to dispose them such that the inner periphery side and the outer periphery side are inverted. In  FIG. 5 , an Example is illustrated in which these are inversely disposed. 
     In  FIG. 5 , the winding type stator  4  is disposed in an outermost periphery portion, and the first permanent magnet field system  1   b , the modulation magnetic pole  3 , and the second permanent magnet field system  2  are disposed in an inner periphery side in order. In this case, a recess and a projection of the core  12   b  of the first permanent magnet field system  1   b  are provided on the outer periphery side, and a part equivalent to the projection portion is configured to be a curved surface. Furthermore, since the core  12   b  is located on an outer periphery side of the permanent magnets  11   a  and  11   b  of the first permanent magnet field system  1   b , in a case where the first permanent magnet field system  1   b  is rotated at a high speed, the core  12   b  can prevent scattering due to a centrifugal force applied to the permanent magnets  11   a  and  11   b , and the intensity of the first permanent magnet field system  1   b  can be increased. 
     Example 4 
     Then, a fourth Example according to the present invention is described by using  FIG. 6 .  FIG. 6  is an Example of a method of manufacturing the core  12   b  of the first permanent magnet field system  1   b  illustrated in  FIG. 3 . 
     A figure at the top in  FIG. 6  illustrates a tape-like magnetic material thin plate  12   b ′, which is thin in a paper surface direction and is long and narrow to the left and right. First, as illustrated in a figure in the middle in  FIG. 6 , the tape-like magnetic material thin plate  12   b ′ is cut to form a magnetic material thin plate  12   b ″ having the projection portion  13  and the recess portion  14 . Then, as illustrated in the figure at the bottom in  FIG. 6 , the recess portion  14  is bended such that the magnetic material thin plate  12   b ″ is configured to be a round shape. After a complete round has been made, by overlapping a projection portion with another projection portion and a recess portion with another recess portion, and for example, by attaching each surfaces, the core  12   b  can be made into a layered structure. In this way, by configuring a layered core from a thin tape-like magnetic material thin plate, it is possible to significantly increase a material utilization rate compared to a case where a core part is cut out from a flat plate-like magnetic material thin plate. 
     Example 5 
     Then, a fifth Example according to the present invention is described by using  FIG. 7 .  FIG. 7  is a sectional view of a magnetic gear-type electric rotating machine according to the fifth Example of the present invention. It is different from  FIG. 3  in that the first permanent magnet field system  1   b  is replaced with a first permanent magnet field system  1   c , and the permanent magnet magnetic poles  11   a  and  11   b  of the first permanent magnet field system  1   b  is replaced with permanent magnet magnetic poles  11   c  and  11   d.    
     In this Example, since a recess and a projection are provided on a surface of the permanent magnet magnetic poles  11   c  and  11   d  of the first permanent magnet field system  1   b , and since a distance between an edge in the circumferential direction of the permanent magnet magnetic poles  11   c  and  11   d  and the pole pieces  31  is far, an eddy current occurring on the permanent magnet magnetic poles  11   c  and  11   d  can be prevented, and a loss can be decreased. That is, an inner peripheral surface of the permanent magnet magnetic pole  11   c  and the permanent magnet magnetic pole  11   d  and an outer peripheral surface of the core  12   b  form a cylindrical shape having a radius r7 and centering on the point O, and a thickness d of the permanent magnet magnetic poles  11   c  and  11   d  changes in a circumferential direction of this cylindrical surface. The thickness d of the permanent magnet magnetic poles  11   c  and  11   d  becomes thick at the projection portion  13  and becomes thin at the recess portion  14 . Therefore, the thickness d is large at a central part in the circumferential direction of the permanent magnet magnetic poles  11   c  and  11   d , and the thickness d is small at an edge in the circumferential direction thereof. 
     Example 6 
     In  FIG. 7 , an Example has been illustrated in which the recess and the projection are provided on the surface of the permanent magnet magnetic poles  11   c  and  11   d  of the first permanent magnet field system  1   c ; however, the recess and the projection may also be provided on a surface of the second permanent magnet field system  2 . In  FIG. 8 , an Example is illustrated in which the recess and the projection are provided on the surface of the second permanent magnet field system. 
       FIG. 8  is different from  FIG. 3  in that the second permanent magnet field system  2  is replaced with a second permanent magnet field system  2   a , and permanent magnet magnetic poles  21   a  and  21   b  of the second permanent magnet field system  2   a  is replaced with permanent magnet magnetic poles  21   c  and  21   d.    
     In this Example, since the recess and the projection are provided on the surface of the permanent magnet magnetic poles  21   c  and  21   d  of the second permanent magnet field system  2   a , and since a distance between an edge in the circumferential direction of the permanent magnet magnetic poles  21   c  and  21   d  and the pole pieces  31  is far, an eddy current occurring on the permanent magnet magnetic poles  21   c  and  21   d  can be prevented, and a loss can be decreased. That is, an outer peripheral surface of the permanent magnet magnetic pole  21   c  and the permanent magnet magnetic pole  21   d , and an inner peripheral surface of the core  22  form a cylindrical shape having a radius r8 and centering on the point O, and a thickness d of the permanent magnet magnetic poles  21   c  and  21   d  changes along a circumferential direction of this cylindrical surface. The thickness d of the permanent magnet magnetic poles  21   c  and  21   d  becomes thick at the projection portion  13  and becomes thin at the recess portion  14 . Therefore, the thickness d is large at the central part of the permanent magnet magnetic poles  21   c  and  21   d  in a circumferential direction, and the thickness d becomes small at an edge in the circumferential direction. 
     It is also possible to combine the configuration in  FIG. 7  in which the recess and the projection are provided on the surface of the permanent magnet magnetic poles  11   c  and  11   d  of the first permanent magnet field system  1   b , and the configuration in  FIG. 8  in which the recess and the projection are provided on the surface of the permanent magnet magnetic poles  21   c  and  21   d  of the second permanent magnet field system  2   a.    
     Note that in the descriptions above, a radial gap type magnetic gear having an air gap in an outer periphery direction of the rotational shaft has been used; however, the above embodiments can also be realized in the same way by using other types (e.g. axial gap type having an air gap in an axial direction of the rotational shaft, a linear type which performs a linear drive, etc.). 
     In any of the embodiments, Examples have been given in which there are 8 poles in the first permanent magnet field system, 34 poles in the second permanent magnet field system, and 21 poles in the pole pieces; however, these embodiments can also be realized in the same way by using another number or another combination of numbers. 
     Furthermore, the above embodiments can also be realized in the same way in a magnetic gear device having no winding type stator. 
     REFERENCE SIGNS LIST 
     
         
           1 ,  1   a ,  1   b ,  1   c  first permanent magnet field system 
           2  second permanent magnet field system 
           3  modulation magnetic pole 
           4  winding type stator 
           11   a ,  11   b ,  11   c ,  11   d  first permanent magnet field system permanent magnet magnetic pole 
           12 ,  12   a ,  12   b ,  12   b ′,  12   b ″ first permanent magnet field system core 
           13  projection portion 
           14  recess portion 
           15   a ,  15   b  edge of tape-like magnetic material thin plate 
           21   a ,  21   b  permanent magnet magnetic pole of second permanent magnet field system 
           22  core of second permanent magnet field system 
           31  pole piece 
           32  non-magnetic case