Abstract:
The present invention provides an axial air-gap rotary electric machine with which it is possible to achieve downsizing and increased output as well as an improvement in the support strength of a molded resin and housing and a reduction in the manufacturing cost of the housing. Provided is an axial air-gap rotary electric machine having: a stator in which a plurality of core members, which have at least an iron core and a coil, are arranged in a circular shape centered around a rotating shaft and curved around the inner peripheral surface of a housing; and a rotor that faces an end surface of the iron core with a prescribed air gap therebetween in the radial direction of the rotating shaft. Therein, the housing has, in the surface facing the stator, a hole that communicates with the outside, and the stator has a resin molded portion formed by filling a resin into at least the surface of the core members facing the inner peripheral surface of the housing, and into the hole, and molding integrally.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an axial air-gap rotary electric machine, and relates to an axial air-gap rotary electric machine for fixing a stator to a housing. 
       BACKGROUND ART 
       [0002]    An axial gap-type rotary electric machine is arranged with a cylindrical stator and a disk-shaped rotator facing each other in a rotation axis diameter direction with a predetermined air gap interposed therebetween. The stator includes multiple iron cores arranged along the inner periphery direction of the housing unit and coils wound around the iron cores. Since a gap surface generating a torque increases substantially in proportional to a square of a diameter, the axial air-gap rotary electric machine is considered to be a rotary electric machine suitable for a thin shape. 
         [0003]    In particular, a double rotor type axial gap-type rotary electric machine in which a single stator is sandwiched by two rotators can ensure twice a gap area size, and therefore, this attracts attention as a structure that may be able to provide more superior characteristics. In the double rotor type axial gap-type rotary electric machine, the iron cores and the coils are arranged independently, and therefore, they are often supported and fixed on a housing with mold resin. A torque repulsive force in a diameter direction and an attraction force in an axial direction are exerted on the stator as an electromagnetic force received by the iron core. In the double rotor type axial gap-type rotary electric machine, the axial direction attraction force between the rotator and the stator is balanced, and therefore, a load in the axial direction is not generated in the stator in the ideal case. In reality, however, when an unbalance occurs in the axial direction attraction force due to an unbalance of the gap and dimensional variations in the components, the load in the axial direction is generated. Therefore, the interface between the mold resin and the housing is required to have a sufficient strength for supporting the load in the peripheral direction and the axial direction. [ 0004 ] 
         [0004]    Patent Literature 1 discloses a method for providing a groove on an inner periphery surface of a housing and making a mold resin and the housing into a structure for making an engagement with a recess and projection shape to support them, and a method for combining the groove and an insert member to support them. 
       CITATION LIST 
     Patent Literature 
       [0005]    PATENT LITERATURE 1: Japanese Patent Application Laid-Open No. 2007-60788 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    In this case, an adhesion force between the mold resin and the housing greatly changes in accordance with a surface state of the housing, a temperature during resin injection, a condition of pressure, and the like. In an actual usage environment of a rotary electric machine, thermal loads, vibration, and the like may be applied. Further, the rotary electric machine may be used over a long period of time such as several years to several dozen years. Therefore, supporting the core member with only the adhesion force of the mold resin and the housing may not be sufficient in terms of reliability. 
         [0007]    On the other hand, like Patent Literature 1, the structure provided with the insert member and the groove of the inner periphery surface of the housing is a structure in which the mold resin and the housing mesh with each other, and therefore, even if the mold resin is detached from the housing, the iron core and the like (the core member) can be supported on the housing, and this can be said to be a structure having a high support strength and having a high level of reliability. 
         [0008]    However, the groove processing to the inner periphery surface of the housing can be a factor to increase the processing time and the processing cost for a lathe, a broaching machine, an NC machine, and the like. There is a method for providing a groove in advance when a housing is molded, but a groove shape cannot be changed in accordance with a load applied to the interface and the shape of the core, and therefore, this may be a factor to increase the cost of many types of products with the same housing. In order to reliably support the mold resin and the housing in accordance with this method, it is necessary to provide a groove deep enough to allow the mold resin and the groove of the housing to engage with each other even in a case where the mold resin is detached and the resin shrinks due to the weight reduction of the stripped surface. Therefore, an adequate housing thickness is required. 
         [0009]    In the rotary electric machine held by the mold resin, transfer molding for pressurizing and filling heated resin may be performed from the perspective of strength and mass production. In this case, a high pressure is applied to the housing during molding. In a case where the groove processing is applied, the thin housing surface may surrender to the pressure from the mold resin to be broken. 
       Solution to Problem 
       [0010]    To achieve the above object, for example, configurations described in claims are applied. That is, the configurations include an axial air-gap rotary electric machine including a stator in which a plurality of core members having at least an iron core and a coil are arranged in an annular shape along an inner periphery surface of a housing around a rotation axis, and a rotator facing an end surface of the iron core with a predetermined air gap interposed in a rotation axis diameter direction, wherein the housing has a hole portion, in communication with an outside, in a surface facing the stator, and the stator has a resin mold portion integrally molded by filling resin into at least a side surface of the plurality of the core members which faces the inner periphery surface of the housing and the hole portion. 
       Advantageous Effects of Invention 
       [0011]    According to an aspect of the present invention, the resin mold portion for fixing the stator and the housing is a hole, and therefore, the processing is easy. Further, since it is a hole portion for penetrating through the housing, the tensile strength exerted on the end portion of the resin filled in the hole portion can be relieved in accordance with the force exerted in the rotation axis direction and the rotation axis diameter direction, so that the damage of the housing can be prevented. 
         [0012]    The problems, configurations, and the effects other than those explained above would be understood from the following explanation about the embodiments. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1A  is a cross sectional view illustrating a configuration of a double rotor-type axial air-gap motor according to a first embodiment to which the present invention is applied.  FIG. 1B  is a portion perspective view illustrating an overview of an armature configuration of a motor according to a first embodiment. 
           [0014]      FIG. 2  is a perspective view illustrating a core member for a single slot of a motor according to the first embodiment. 
           [0015]      FIG. 3  is a schematic diagram illustrating resin mold of the stator according to the first embodiment. 
           [0016]      FIG. 4  is a partially enlarged view illustrating an example of a fixation area (hole portion) according to the first embodiment. 
           [0017]      FIG. 5A  is a partially enlarged view illustrating an example of a holding form according to the first embodiment.  FIG. 5B  is a partially enlarged view illustrating another example of a holding form according to the first embodiment. 
           [0018]      FIG. 6A  is a partially enlarged view illustrating an example of a fixation area according to a comparative example.  FIG. 6B  is a schematic diagram illustrating an example of an effect caused on a housing by a protruding portion of a resin mold portion. 
           [0019]      FIG. 7A  is a partially enlarged view illustrating an example of a holding form according to a second embodiment.  FIG. 7B  is a partially enlarged view illustrating another example of a holding form according to the second embodiment. 
           [0020]      FIG. 8  is a partially enlarged view illustrating a configuration of a fixation area according to a third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0021]    Hereinafter, modes for carrying out the present invention will be explained with reference to drawings.  FIG. 1( a )  illustrates a cross sectional view expressing a schematic configuration of a double rotor-type axial gap-type permanent magnet synchronous motor  1  (which may be hereinafter simply referred to as a “motor  1 ”) according to the first embodiment to which the present invention is applied. 
         [0022]    The motor  1  is arranged so that a donut-shaped stator  19  arranged along an inner periphery surface of a housing  50  is sandwiched by two disk-shaped rotators  30  with a predetermined air gap in a rotation axis diameter direction so that the two disk-shaped rotators  30  face each other. The center of the disk of the rotator  30  is fixed to the rotation axis  40 . The rotation axis  40  is arranged to penetrate through the central portion of the stator  19 , and both end portions are rotatably fixed to brackets  60  with bearings  70 . The end brackets  60  are fixed at around both opening end portions of the housing  50  made in a substantially cylindrical form. 
         [0023]    The rotator  30  includes a permanent magnet  31  on a circular yoke  33  with a back yoke  32  interposed therebetween. The permanent magnet includes multiple flat plate-shaped magnets made in a substantially fan shape around the direction of the rotation axis  70 , and is arranged with magnets having different polarities in the rotation direction. The permanent magnet  31  is made of Ferrite, but the embodiment is not limited thereto. 
         [0024]      FIG. 1( b )  is a perspective view schematically expressing an armature configuration of the motor  1 . The stator  19  includes twelve core members  20  arranged along the inner periphery of the housing  50  in such a manner that the rotation axial center A is the central direction. A single core member  20  constitutes a single slot. The core members  20  are integrally formed with each other with resin mold, and the core members  20  and the inner periphery of the housing  50  are integrally formed with each other with resin mold, and they can be fixed to the stator. 
         [0025]      FIG. 2  is a perspective view expressing a configuration of the core member  20 . The core member  20  includes an iron core  21 , a bobbin  22 , and a coil  23 . The iron core  21  is a laminated iron core made of a pillar body of which end surface facing the rotator  30  has a substantially trapezoid shape. The laminated iron core is obtained by laminating, from rotation axial center A to the inner periphery surface of the housing, plate forms (including tapes) including magnetic material in such a manner that a width of the plate piece gradually increases. The iron core  21  is not limited thereto, and may be a dust iron core and a machined iron core, or may be such that a cross section in the rotation axis direction has a T, H, or I character shape. It should be noted that the magnetic material may be amorphous, but the embodiment is not limited thereto. 
         [0026]    The bobbin  22  includes a tube shape having substantially the same internal diameter as the external diameter of the iron core  21 . At around the both opening portions of the bobbin  22 , flange portions  22   b  are provided to extend for a predetermined width over the entire periphery from the external tube portion in the direction perpendicular thereto. In the external tube portion, the coil  23  is wound between both of the flange portions  22   b.    
         [0027]    In the motor  1  having such configuration, an alternate electric current is applied to the coil  23  with an inverter (not shown), and a rotation magnetic field generated in the stator  19  and a direct current magnetic field of the rotator  30  attract and repels each other, so that a torque is generated. At this occasion, a torque repulsive force in a peripheral direction is exerted to the rotator  30  in a direction opposite to the rotation direction. In a case where the magnetic attraction force between the upper and lower rotator  30  become unbalanced because of variations of components dimensions and assembly precision, a force is also exerted in the rotation axis direction. As described above, a load in the peripheral direction and the axial direction is applied to the interface between the mold resin and the housing  50 . One of the characteristics of the first embodiment is that the resin mold is used for such load. 
         [0028]      FIG. 3  schematically illustrates a resin mold step for integrally forming the core members  20  with each other and the inner periphery of the housing  50 . The housing  50  is inserted into a lower die  62  having a substantially the same internal diameter, and a middle die  61  in a tube shape for forming an axial center space through which the rotation axis penetrates later is placed from the opposite side opening of the housing  50  into the center of the lower die  62 . The core members  20  are arranged in an annular shape around the middle die  61 . At this occasion, the flange portion  22   b  of the bobbin performs positioning of the diameter direction and positioning of adjacent core members  20  in the rotation axis rotation direction. 
         [0029]    Thereafter, an upper die having substantially the same external diameter as the internal diameter of the housing  50  and having a cylindrical space in the center through which the middle die  61  penetrates is inserted from the housing opening at the side opposite to the lower die  62 , so that the core member  20  is sandwiched and supported. Thereafter, resin can be sealed from the surface opposite to the upper die and lower die  62 . The resin is filled, without any gap, into between the core members  20 , the inner periphery surface of the housing  50 , the direction of the middle die  61 , and a surface of the flange portion  22   b  of the bobbin opposite to the rotator  30 , and the resin also gradually flows into the fixation area  10   a  (hole portion) provided in the housing  50 . For example, in a case where the core members  20  are coupled with each other with a ring member such as metal, and an annular shape is maintained, the resin can be filled into between the housing  50  and a surface of the core member  20  at least opposite to the inner periphery surface of the housing  50  (side surface of trapezoid lower bottom side). 
         [0030]    The fixation area  10   a  is a hole that penetrates through the inside and the outside of the housing  50 , and is provided at a predetermined position to fix the stator  19  at a desired position of the housing  50 . In the first embodiment, the fixation area  10   a  is considered to be provided substantially at the middle of the width of the stator  19  in the rotation axis direction. There may be multiple fixation areas  10   a . In the present embodiment, the fixation area  10  is a circular hole, but may also be a semicircular, polygonal shape, or the like. 
         [0031]      FIG. 4  illustrates an enlarged view around the fixation area  10   a . The fixation area  10   a  includes a fixed portion  40   a  formed with a protruding portion  9  where the resin flows into, and a taper portion  40   b  where the resin does not flow into. When the resin is also filled in the fixation area  10   a  and eventually cured, the protruding portion  9  is formed. More specifically, a mold portion  11  in a shape integrally having resin filled around the stator  19  and the protruding portion  9  formed in the fixed portion  40   a  is formed. 
         [0032]    In this case, an advantage as to why the fixation area  10   a  is configured to penetrate through the housing  50  will be explained with reference to a comparative example.  FIG. 6( a )  illustrates a fixation area according to a comparative example. In  FIG. 6( a ) , reference symbol  110   a  denotes a fixation area of the comparative example. In the comparative example, it is not made as a hole penetrating through the housing  50 , and is formed as a recessed portion on the inner periphery side without any penetration. As a result, in the housing  50 , a thin thickness portion  141   b  is formed on the extension of the fixation area  110   a.    
         [0033]      FIG. 6( b )  illustrates an enlarged view around the fixation area  110   a . When a force in the rotation axis direction and the rotation axis diameter direction is exerted on the stator  19 , forces F 1  to F 3  are generated in the protruding portion  9  with the housing  50 . In this case, when an end edge (corner) portion of the protruding portion  9  is considered (dotted line portion), a tensile strength is generated on a part of all of the edge against the forces in the rotation axis direction such as F 1  to F 3 , and the load is generated in the housing  50 . With such load, a crack  42  may be made in the housing  50 . 
         [0034]    In contrast, in the present embodiment, the fixation area  10   a  is configured to penetrate through the housing  50 , and therefore, a force exerted on the edge (corner) at the end of the protruding portion  9  in accordance with the force exerted from the rotation axis diameter direction and the rotation axis direction can be relieved. More specifically, when a force is exerted from the rotation axis diameter direction and the rotation axis direction to the stator  19 , the force in the rotation axis diameter direction and the rotation axis direction is exerted on the protruding portion  9  accordingly. In the cured protruding portion  9 , mainly, these forces most greatly propagate to the edge (corner) at the end of the protruding portion  9 , but because the fixation area  10   a  is a penetration hole, the fixation area  10   a  serves as a space in which the edge escapes to the outside of the housing  50  and the taper portion  40   b.    
         [0035]    In the fixation area  10   a , the protruding portion  9  is formed while leaving the taper portion  40   b . This is advantageous for more effectively preventing the resin from leaking out of the fixation area  10   a.    
         [0036]      FIG. 5( a )  illustrates how a holding form  60  is applied in order to prevent the resin from leaking out of the fixation area  10   a . The holding form  60  includes a projection shape  60   a  having substantially the same external diameter as the internal diameter of the fixation area  10   a , and the projection shape  60   a  is embedded in the fixation area  10   a  from the outer periphery side of the housing  50 . As shown in the drawing, an L-shaped gap serving as a leakage flow path of resin is formed between the projection shape  60   a  and the fixation area  10   a , but such bent flow path increases the resistance of the resin, and this is suitable for preventing the leakage. When the leakage resistance is high, the filling pressure of resin can be enhanced accordingly. 
         [0037]    It should be noted that the present invention is not limited to the configuration provided with the taper portion  40   b , and as illustrated in  FIG. 5( b ) , the entire fixation area  10   a  may be filled with resin. In this case, the holding form  63  may be a flat surface member for holding the fixation area  10   a  from the outer periphery side. An advantage of easily removing the holding form  63  after filling the resin can be expected. 
         [0038]    The internal side surface of the fixation area  10   a  may be formed in a screw hole shape. In this case, when a surface of the holding form  60  facing the fixation area  100  is made into a screw shape, the holding form  60  can be reliably fixed to the housing, or this can suppress a deviation of the position of the holding form  60  and can suppress leakage of the resin caused by the filling pressure during molding. 
         [0039]    According to the motor  1  of the first embodiment, the stress of the stator  19  and the housing  50  against the force in the rotation axis diameter direction and the rotation axis direction are improved, and the fixing of them both can be made reliably, and this can greatly contribute to the performance of the motor  1 . 
         [0040]    Since the fixation area  10   a  is the penetration hole, the protruding portion  9  does not damage the housing  50  because of the force exerted on the stator  19  in the rotation axis diameter direction and the rotation axis direction, and a sufficient support strength can be ensured. 
         [0041]    The molding step for molding the core members  20  with each other and the housing  50  also serves as the step of forming the protruding portion  9 , and therefore, the working efficiency is significantly improved. The fixation area  10   a  can be obtained from a simple step of providing the hole in the housing  50 . 
       Second Embodiment 
       [0042]    One of the characteristics of a motor  1  according to the second embodiment is that a holding form  60  is installed from an inner periphery side of a housing  50 .  FIGS. 7( a ) and 7( b )  illustrate enlarged views illustrating around the fixation area  10   a . The same portions as those of the first embodiment will be denoted with the same reference numerals, and explanation thereabout is omitted. 
         [0043]    First, the holding form  60  of  FIG. 7( a )  has a substantially C-shaped cross section constituted by a bottom surface  60   b  and a side surface  60   c , and has a shape having a flange portion  60   d  extending over the entire periphery of the opening portion side (pot shape). The housing  50  is provided with a hole having substantially the same internal diameter as the external diameter of the tube portion constituted by the bottom surface  60   b  and the side surface c, and is provided with a circular groove in which a portion around the edge of the inner periphery side of the housing  50  of the hole substantially matches the diameter of the flange portion  60   d . When the holding form  60  is fit in the fixation area  10   a , the bottom surface  60   b  is at a position matching the outer periphery surface of the housing  50 , and the flange portion  60   d  is at a position matching the inner periphery surface of the housing  50 . The resin is filled after the holding form  60  is installed in the fixation area  10   a  from the inner periphery surface of the housing  50 . 
         [0044]    The flange portion  60   d  serves as a retainer in the diameter direction. More specifically, the flange portion  60   d  has an external diameter which is larger than the internal diameter of the housing side opening portion of the fixation area  10   a , and therefore, when a force in the diameter direction is received due to the pressure of the resin, the flange portion  60   d  is engaged with the housing  50 , and the flange portion  60   d  functions as a lid for the resin. When the flange portion  60   d  is pressed onto the housing, a gap from the housing  50  is reduced, and the leakage of the resin is suppressed. When the flange portion  60   d  is arranged with a ramp provided in the housing  50 , this can suppress the mold resin from entering into a space where the gap from the housing  50  is narrow, and can prevent the holding form  60  itself from moving to the side of the core member  20 . 
         [0045]    The present modification can be achieved by just installing the holding form  60  in the housing  50  in a stage before the resin mold step, and can save the trouble of arranging or removing the leakage prevention form at the outer periphery side of the housing  50 . 
         [0046]    The shape of the holding form  60  is such that the outer periphery thereof comes into close contact with the penetration hole and the ramp provided in the housing  50 , and therefore, a sufficient support force is achieved for the force exerted on the stator  19  in the rotation axis diameter direction and the rotation axis direction. 
         [0047]    The holding form  60  comes into contact with the housing  50  by using the filling pressure of the resin, so that the resin leakage can be prevented. 
         [0048]    It is the holding form  60  that receives the load with a tensile strength generated at the end edge (corner) of the protruding portion  9 , and therefore, even if a crack is generated, the housing  50  can be maintained by only replacing the holding form  60 . Further, such cracks can be solved when the holding form  60  is constituted by a member having a higher strength (metal such as aluminum), and when the holding form  60  is constituted by resin, rubber, and the like, the force of the edge portion can be relieved with an elastic stress. 
         [0049]    In a case of the holding form  60  as illustrated in  FIG. 7( a ) , it is sufficient for the holding form  60  to have only a surface covering the protruding portion  9  and a surface facing the inner periphery surface of the housing. The holding form  60  is not limited to the shape in this drawing. 
         [0050]    Subsequently, a configuration of another holding form  60  is illustrated in FIG  7 ( b ). A fixation area  10   a  has an internal diameter in a (circular) truncated cone shape in a tapered shape in which a cross section gradually decreases from the inner periphery side to the outer periphery side of the housing  50 . The holding form  60  includes a (circular) truncated cone having an outer periphery shape substantially matching a top portion (housing outer periphery side) side of the circular truncated cone, and puts a lid at the top portion side of the fixation area  10   a  by using the filling pressure of the resin. More specifically, the holding form  60  is a truncated cone, and therefore, the holding form  60  has an external diameter portion larger than the internal diameter of the housing outer periphery side opening of the fixation area  10   a , and the surface at the lower bottom side is located at the outer periphery side with respect to the inner periphery surface of the housing. 
         [0051]    As compared with the configuration of  FIG. 7( a )  explained above, the holding form  60  having a simpler configuration can be realized in  FIG. 7( b ) . 
         [0052]    As the width of the fixed portion  40   a  in the rotation axis direction increases toward the bottom surface side (at the side of the core member  20 ) in the truncated cone-shaped fixation area  10   a , the support strength of the stator  19  can be sufficiently ensured. With this structure, the resin leakage can be effectively suppressed with the simpler holding member. 
       Third Embodiment 
       [0053]    One of the characteristics of a motor  1  according to the third embodiment is a configuration in which a fixation area  10   a  also serves as a connection port for extending a connecting line of each core member  20  to the outside of the housing  50 . 
         [0054]      FIG. 8  illustrates a fixation area  10   a  according to the third embodiment. The same portions as those of the first embodiment will be denoted with the same reference numerals, and explanation thereabout is omitted. 
         [0055]    The fixation area  10   a  is provided on the housing  50  close to an output side or an anti-output side of the core member  20 . More preferably, the fixation area  10   a  is arranged at a side where the connecting line  23   a  extends from the core member  20  (output or anti-output side). 
         [0056]    The connecting line  23   a  extending from each core member  20  is arranged along the inner periphery surface of the housing  50  toward the fixation area  10   a , and is integrally formed with the stator  19  with resin mold. The connecting line  23   a  passes through the fixation area  10   a  to extend to the outside of the housing. 
         [0057]    The outer periphery side of the housing  50  of the fixation area  10   a  is provided with a thick portion in a diameter direction such as, e.g., a base  90  for installing a terminal box (not shown). 
         [0058]    According to the third embodiment, the connection port of the connecting line  23   a  and the fixation area  10   a  can be shared, and the processing cost can be reduced. 
         [0059]    Just like the base  90 , the periphery of the fixation area  10   a  has a thick thickness to protrude to the outer periphery side. Therefore, the strength around the fixation area  10   a  can be ensured. 
         [0060]    In the third embodiment, the fixation area  10   a  is configured to be installed at the output axial or anti-output axial side of the core member  20 , but the embodiment is not limited thereto. The fixation area  10   a  may be installed in proximity to the center in the axial direction of the core member  20 . This can be changed as necessary in accordance with, e.g., a position where the connecting line  23   a  is extended. 
         [0061]    Multiple fixation areas  10   a  serving as connection ports may be provided. 
         [0062]    The embodiments for carrying out the present invention have been hereinabove explained, but various changes can be made in the present invention without contradicting the gist of the present invention. For example, in the above explanation, for example, the double rotor-type axial gap-type permanent magnet synchronous motor has been explained, but a single rotor type may be used, or axial gap-type permanent magnet synchronous motors in other forms may also be used. The present invention can also be applied to a synchronous reluctance motor, a switched reluctance motor, or an induction motor having no permanent magnet. Further, the present invention can also be applied to a generator instead of a motor. 
         [0063]    A cover may be provided on the outer periphery surface of the fixation area  10   a  so as to cover the protruding portion  9  of the mold resin. As a result, degradation of the protruding portion  9   a  can be prevented. 
         [0064]    The fixation area  10   a  may be provided in an area where a part or all thereof faces the diameter direction of the core member  20 , and the position, the number, and the shape thereof is not particularly limited. For example, a single fixation area  10   a  may be provided, or multiple fixation areas  10   a  may be provided. A single fixation area  10   a  or multiple fixation areas  10   a  may be provided in the rotation axis direction. The cross-sectional shape in the fixation area may be in a circular, elliptic, or polygonal shape. In a case where multiple fixation areas  10   a  are provided, it is not necessary to make all of them to be in the same shape, and the fixation areas  10   a  may be formed in different shapes. As described above, when the number and the shape of fixation areas provided for a single stator are increased, the support strength of the mold resin for the housing can be improved. 
       REFERENCE SIGNS LIST 
       [0065]      1  . . . double rotor-type axial air-gap permanent magnet synchronous motor (motor),  9  . . . protruding portion,  10   a  . . . fixation area,  11  . . . mold portion,  19  . . . stator,  20  . . . core member,  21  . . . iron core,  22  . . . bobbin,  22   b  . . . flange portion,  23  . . . coil,  23   a  . . . connecting line,  24  . . . core member,  40  . . . rotation axis,  40   a  . . . fixed portion,  40   b  ... taper portion,  42  . . . crack,  49  . . . end bracket,  50  ... housing,  50   a  . . . engagement unit,  60  . . . holding form,  60   a  . . . projection shape,  60   b  . . . bottom surface,  60   c  . . . side surface,  60   d  . . . flange portion,  61  . . . middle die,  62  . . . lower die,  63  . . . holding form,  70  . . . bearing,  90  . . . base,  110   a  . . . protruding portion,  141   a  . . . fixation area,  141   b  . . . thin thickness portion, A . . . rotation axis, F 1 , F 2 , F 3  . . . force