Patent Publication Number: US-2023163648-A1

Title: Rotor, motor, blower, air conditioner, and manufacturing method of rotor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a U.S. national stage application of International Patent Application No. PCT/JP2020/014062 filed on Mar. 27, 2020, the disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a rotor, a motor, a blower, an air conditioner, and a manufacturing method of the rotor. 
     BACKGROUND 
     As a rotor used for a motor, there has been proposed a rotor including a first permanent magnet and a second permanent magnet arranged on an inner side of the first permanent magnet and fixed to the first permanent magnet (see Patent References  1  and  2 , for example). 
     PATENT REFERENCE 
     Patent Reference 1: Japanese Patent Application Publication No. 2011-87393 
     Patent Reference 2: Japanese Patent Application Publication No. 2005-151757 
     However, in the rotors described in the Patent References 1 and 2, there is a possibility that the first permanent magnet falls off of the second permanent magnet arranged on the inner side, when centrifugal force acts on the rotor during rotation, when a temperature change occurs, or the like. 
     SUMMARY 
     An object of the present disclosure is to prevent the falling off of the permanent magnet. 
     A rotor according to an aspect of the present disclosure includes a rotary shaft and a rotor body supported by the rotary shaft. The rotor body has a first permanent magnet and a second permanent magnet. The second permanent magnet is supported by the rotary shaft. The first permanent magnet has a plurality of pillar parts arranged at intervals in a circumferential direction of the rotor body and a first overhang part that is in contact with a first end part of the second permanent magnet in an axial direction of the rotary shaft. The first permanent magnet is supported by the second permanent magnet on an outer side of the second permanent magnet. The first overhang part and the first end part are joined to each other. 
     According to the present disclosure, the falling off of the permanent magnet can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a side view showing the configuration of a rotor according to a first embodiment. 
         FIG.  2    is a plan view showing the configuration of the rotor according to the first embodiment. 
         FIG.  3    is a bottom view showing the configuration of the rotor according to the first embodiment. 
         FIG.  4    is a plan view showing the configuration of a second permanent magnet according to the first embodiment. 
         FIG.  5    is a sectional view of the rotor shown in  FIG.  1    taken along the line A 5 -A 5 . 
         FIG.  6    is a sectional view of the rotor shown in  FIG.  5    taken along the line A 6 -A 6 . 
         FIG.  7    is a flowchart showing a manufacturing process of the rotor according to the first embodiment. 
         FIG.  8    is a flowchart showing details of a process of forming a rotor body according to the first embodiment. 
         FIG.  9    is a plan view showing the configuration of a rotor body according to a comparative example. 
         FIG.  10    is a graph showing a distribution of surface magnetic flux density of the rotor body according to the first embodiment and a distribution of surface magnetic flux density of the rotor body according to the comparative example. 
         FIG.  11    is a partial sectional view showing the configuration of a rotor body according to a second embodiment. 
         FIG.  12    is a partial sectional view showing the configuration of a rotor body according to a modification of the second embodiment. 
         FIG.  13    is a sectional view showing the configuration of a rotor body according to a third embodiment. 
         FIG.  14    is a plan view showing the configuration of the second permanent magnet according to the third embodiment. 
         FIG.  15    is a partial sectional view showing the configuration of a rotor body according to a first modification of the third embodiment. 
         FIG.  16    is a partial sectional view showing the configuration of a rotor body according to a second modification of the third embodiment. 
         FIG.  17    (A) is an enlarged plan view showing a part of the configuration of a rotor body according to a fourth embodiment. 
         FIG.  17 (B)  is an enlarged bottom view showing a part of the configuration of the rotor body according to the fourth embodiment. 
         FIG.  18    is a side view showing the configuration of a rotor body according to a first modification of the fourth embodiment. 
         FIG.  19 (T)  is an enlarged plan view showing the configuration of the rotor body according to the first modification of the fourth embodiment. 
         FIG.  19 (B)  is an enlarged bottom view showing the configuration of the rotor body according to the first modification of the fourth embodiment. 
         FIG.  20    (A) is an enlarged plan view showing a part of the configuration of a rotor body according to a second modification of the fourth embodiment. 
         FIG.  20 (B)  is a sectional view of the rotor body shown in  FIG.  20 (A)  taken along the line A 20 -A 20 . 
         FIG.  21    is a plan view showing the configuration of a rotor body according to a fifth embodiment. 
         FIG.  22    is a sectional view showing the configuration of the rotor body according to the fifth embodiment. 
         FIG.  23    is a sectional view showing the configuration of a rotor body according to a modification of the fifth embodiment. 
         FIG.  24    is a plan view showing the configuration of the second permanent magnet according to the modification of the fifth embodiment. 
         FIG.  25    is a plan view showing the configuration of a rotor according to a sixth embodiment. 
         FIG.  26    is a sectional view of the rotor shown in  FIG.  25    taken along the line A 26 -A 26 . 
         FIG.  27    is a plan view showing the configuration of a rotor according to a modification of the sixth embodiment. 
         FIG.  28    is a sectional view of the rotor shown in  FIG.  27    taken along the line A 28 -A 28 . 
         FIG.  29    is a side view showing the configuration of a rotor body according to a seventh embodiment. 
         FIG.  30    is a sectional view showing the configuration of the rotor body according to the seventh embodiment. 
         FIG.  31    is a flowchart showing details of a process for forming the rotor body according to the seventh embodiment. 
         FIG.  32    is a partial sectional view showing the configuration of a rotor body according to a first modification of the seventh embodiment. 
         FIG.  33    is a partial sectional view showing the configuration of a rotor body according to a second modification of the seventh embodiment. 
         FIG.  34 (A)  is a sectional view showing the configuration of a rotor body according to a third modification of the seventh embodiment. 
         FIG.  34 (B)  is another sectional view showing the configuration of the rotor body according to the third modification of the seventh embodiment. 
         FIG.  35    is a configuration diagram showing a partial cross section and a side face of a motor according to an eighth embodiment. 
         FIG.  36    is a diagram schematically showing the configuration of an air conditioner according to a ninth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A rotor, a motor, a blower, an air conditioner, and a manufacturing method of a rotor according to each embodiment of the present disclosure will be described below with reference to the drawings. The following embodiments are just examples and it is possible to appropriately combine the embodiments and appropriately modify each embodiment. 
     An xyz orthogonal coordinate system is shown in the drawings to facilitate the understanding of the description. A z-axis is a coordinate axis parallel to an axis of a rotor. An x-axis is a coordinate axis orthogonal to the z-axis. A y-axis is a coordinate axis orthogonal to both the x-axis and the z-axis. 
     First Embodiment 
       FIG.  1    is a side view showing the configuration of a rotor  1  according to a first embodiment.  FIG.  2    is a plan view showing the configuration of the rotor  1  according to the first embodiment.  FIG.  3    is a bottom view showing the configuration of the rotor  1  according to the first embodiment. As shown in  FIGS.  1  to  3   , the rotor  1  includes a shaft  10  as a rotary shaft, a rotor body  11  supported by the shaft  10 , and a connection part  12  that connects the shaft  10  and the rotor body  11  to each other. The rotor  1  is rotatable about an axis C 1  of the shaft  10 . The shaft  10  extends in the z-axis direction. In the following description, a direction along a circumference of a circle about the axis C 1  of the shaft  10  is referred to as a “circumferential direction”, the z-axis direction is referred to as an “axial direction”, and a direction orthogonal to the axial direction is referred to as a “radial direction”. 
     The rotor body  11  includes a plurality of rare-earth bond magnets  21  as first permanent magnets and a ferrite bond magnet  22  as a second permanent magnet. Namely, two permanent magnets (hereinafter referred to also as “bond magnets”) included in the rotor body  11  are of types different from each other. Specifically, the two permanent magnets included in the rotor body  11  differ from each other in magnetic pole strength (i.e., quantity of magnetism). In the first embodiment, the magnetic pole strength of the rare-earth bond magnet  21  is greater than the magnetic pole strength of the ferrite bond magnet  22 . Further, in the first embodiment, the two bond magnets included in the rotor body  11  differ from each other in the linear expansion coefficient. 
     The rare-earth bond magnet  21  includes a rare-earth magnet and a resin. The rare-earth magnet is a neodymium magnet including neodymium (Nd), iron (Fe) and boron (B), a samarium iron nitrogen magnet including samarium (Sm), iron (Fe) and nitrogen (N), or the like, for example. The resin included in the rare-earth bond magnet is nylon resin, PPS (Poly Phenylene Sulfide) resin, epoxy resin or the like, for example. 
     The ferrite bond magnet  22  includes a ferrite magnet and a resin. The resin included in the ferrite bond magnet  22  is nylon resin, PPS resin, epoxy resin or the like, similarly to the resin included in the rare-earth bond magnet. 
       FIG.  4    is a plan view showing the configuration of the ferrite bond magnet  22 . As shown in  FIG.  4   , the shape of the ferrite bond magnet  22  in a plane parallel to the xy plane is a ring shape about the axis C 1 . Outer peripheral surfaces  22   e  of the ferrite bond magnet  22  form parts of an outer peripheral surface  11   a  (see  FIG.  2   ) of the rotor body  11 . The ferrite bond magnet  22  includes a plurality of (eight in  FIG.  4   ) groove parts  22   f  famed between a plurality of outer peripheral surfaces  22   e  adjoining in the circumferential direction R 1 . The plurality of groove parts  22   f  are arranged at intervals in the circumferential direction R 1  about the axis C 1 . Each groove part  22   f is an elongated groove which is elongated in the axial direction. 
     The ferrite bond magnet  22  is oriented to have polar anisotropy. Bottom surfaces  22   g  of a plurality of groove parts  22   f  adjoining each other in the circumferential direction R 1  have magnetic poles different from each other in the polarity. The arc-shaped arrow F 2  shown in  FIG.  4    indicates the direction of magnetic flux in the ferrite bond magnet  22 . Magnetic flux flowing in from the outer side of a south pole groove part  22   f  in the radial direction advances to a north pole groove part  22   f  adjoining in the circumferential direction. Thus, the rotor  1  does not need a rotor core that forms a magnetic path on the inner side of the ferrite bond magnet  22  in the radial direction. Accordingly, the number of components in the rotor  1  can be reduced and the weight of the rotor  1  can be reduced. 
     As shown in  FIGS.  1  to  3   , the ferrite bond magnet  22  is supported by the shaft  10  via the connection part  12 . The connection part  12  is formed of an unsaturated polyester resin, for example. The connection part  12  includes an inner cylinder part  12   a , an outer cylinder part  12   b  and a plurality of (four in the first embodiment) ribs  12   c . The inner cylinder part  12   a is in a cylindrical shape and fixed to an outer circumferential surface of the shaft  10 . The outer cylinder part  12   b is in a cylindrical shape and fixed to an inner circumferential surface of the ferrite bond magnet  22 . The plurality of ribs  12   c  connect the inner cylinder part  12   a  and the outer cylinder part  12   b  to each other. The plurality of ribs  12   c  radially extend outward in the radial direction from the inner cylinder part  12   a . The plurality of ribs  12   c  are arranged at equal angles in the circumferential direction R 1  about the axis C 1 . Incidentally, the ferrite bond magnet  22  may also be fixed to the shaft  10  directly via no connection part  12 . 
     A plurality of (eight in the first embodiment) rare-earth bond magnets  21  are supported by the ferrite bond magnet  22 . The plurality of rare-earth bond magnets  21  are arranged at intervals in the circumferential direction R 1 . An outer peripheral surface  21   c  of each of the plurality of rare-earth bond magnets  21  forms a part of the outer peripheral surface  11   a  of the rotor body  11 . 
     Each of the plurality of rare-earth bond magnets  21  is oriented to have the polar anisotropy. A plurality of rare-earth bond magnets  21  adjoining each other in the circumferential direction R 1  have magnetic poles different from each other in the polarity. The arc-shaped arrow F 1  shown in  FIGS.  2  and  3    indicates the direction of magnetic flux in the rare-earth bond magnet  21 . Magnetic flux flowing in from the outer side of a south pole rare-earth bond magnet  21  in the radial direction advances to a north pole rare-earth bond magnet  21  adjoining in the circumferential direction R 1 . In the first embodiment, the rotor body  11  includes eight magnetic poles. Incidentally, the number of poles of the rotor body  11  is not limited to  8 . It is sufficient that the number is  2   n  or more. The number n is a natural number greater than or equal to 1. 
       FIG.  5    is a sectional view of the rotor  1  shown in  FIG.  1    taken along the line A 5 -A 5 .  FIG.  6    is a sectional view of the rotor body  11  shown in  FIG.  5    taken along the line A 6 -A 6 . Incidentally, the shaft  10  and the connection part  12  are not shown in  FIG.  5   . As shown in  FIGS.  5  and  6   , the rare-earth bond magnet  21  includes a pillar part  41 , a first overhang part  42  and a second overhang part  43 . 
     The pillar part  41  is arranged in the groove part  22   f  (see  FIG.  4   ) of the ferrite bond magnet  22 . The pillar part  41  is arranged on the outer side in the radial direction relative to the bottom surface  22   g  of the groove part  22   f . The pillar part  41  extends in the axial direction. The length L 41  of the pillar part  41  in the axial direction is greater than the length L 22  of the ferrite bond magnet  22  in the axial direction. The shape of the pillar part  41  as viewed in the −z-axis direction is a fan-like shape, for example. In an xy plane, an inner peripheral surface and an outer peripheral surface of the pillar part  41  are formed in the form of concentric circles. Namely, the thickness of the pillar part  41  in the xy plane is constant in the circumferential direction R 1 . 
     The first overhang part  42  extends inward in the radial direction from an end part  41   a  of the pillar part  41  on the +z-axis side. In other words, the pillar part  41  is situated on the outer side in the radial direction relative to the first overhang part  42 . The first overhang part  42  is in contact with an end part  22   c  of the ferrite bond magnet  22  on the +z-axis side as a first end part. In  FIG.  2   , the width of the first overhang part  42  in the circumferential direction R 1  decreases toward the inner side in the radial direction. The shape of the first overhang part  42  as viewed in the −z-axis direction is a substantially triangular shape, for example. 
     The second overhang part  43  extends inward in the radial direction from an end part  41   b  of the pillar part  41  on the −z-axis side. The second overhang part  43  is in contact with an end part  22   d  of the ferrite bond magnet  22  on the −z-axis side as a second end part. The width of the second overhang part  43  in the circumferential direction R 1  decreases toward the inner side in the radial direction. The shape of the second overhang part  43  as viewed in the −z-axis direction is a substantially triangular shape, for example, similarly to the first overhang part  42 . Incidentally, the shape of the first overhang part  42  and the shape of the second overhang part  43  as viewed in the −z-axis direction are not limited to the substantially triangular shape but may also be different shapes. Further, the rare-earth bond magnet  21  may also be configured to include only one of the first overhang part  42  and the second overhang part  43 . 
     In the first embodiment, the pillar parts  41  and the groove parts  22   f  are joined to each other by integral molding (referred to also as “two-color molding”) of the rare-earth bond magnets  21  and the ferrite bond magnet  22 . In the first embodiment, the integral molding of the rare-earth bond magnets  21  and the ferrite bond magnet  22  means integrating the rare-earth bond magnets  21  and the ferrite bond magnet  22  together by molding the rare-earth bond magnets  21  in a state where the ferrite bond magnet  22  manufactured previously is arranged in a mold. 
     Further, in the first embodiment, the first overhang part  42  and the end part  22   c  of the ferrite bond magnet  22  on the +z-axis side are joined to each other and the second overhang part  43  and the end part  22   d  of the ferrite bond magnet  22  on the −z-axis side are joined to each other. Since the rare-earth bond magnet  21  and the ferrite bond magnet  22  are joined to each other in the axial direction in the first embodiment as described above, a joining area between the rare-earth bond magnet  21  and the ferrite bond magnet  22  can be increased. Accordingly, the falling off of the rare-earth bond magnet  21  from the ferrite bond magnet  22  can be prevented even when peeling occurs at the interface between the ferrite bond magnet  22  and the rare-earth bond magnet  21  due to expansion or contraction caused by a temperature change or centrifugal force acting on the rotor. 
     Next, a manufacturing method of the rotor  1  will be described below by using  FIG.  7   .  FIG.  7    is a flowchart showing a manufacturing process of the rotor  1 . 
     In step ST 1 , the rotor body  11  is formed. Incidentally, details of the step ST 1  will be described later. 
     In step ST 2 , the rotor body  11  is connected to the shaft  10 . In the first embodiment, the rotor body  11  is connected to the shaft  10  by integrating the rotor body  11  and the shaft  10  with each other via the connection part  12 . 
     In step ST 3 , the rotor body  11  is magnetized by using a magnetizer, for example. Specifically, the rare-earth bond magnets  21  and the ferrite bond magnet  22  are magnetized so that the rare-earth bond magnets  21  and the ferrite bond magnet  22  have the polar anisotropy. 
     Next, details of the process of forming the rotor body  11  will be described below by using  FIG.  8   .  FIG.  8    is a flowchart showing the details of the process of foaming the rotor body  11 . The process of foaming the rotor body  11  uses a second mold for molding the ferrite bond magnet  22 , a first mold for molding the rare-earth bond magnets  21  supported by the ferrite bond magnet  22 , and a magnet for the orientation. 
     In step ST 11 , the inside of the second mold for molding the ferrite bond magnet  22  is filled in with the material of the ferrite bond magnet  22 . The ferrite bond magnet  22  is molded by injection molding, for example. Incidentally, the method of molding the ferrite bond magnet  22  is not limited to the injection molding. The ferrite bond magnet  22  may be molded by a different molding method such as press molding. 
     In step ST 12 , the ferrite bond magnet  22  having a predetermined shape is molded while the material of the ferrite bond magnet  22  is oriented. In the step ST 12 , the ferrite bond magnet  22  is molded while the material of the ferrite bond magnet  22  is oriented in a state where a magnetic field having polar anisotropy is generated inside the second mold by using the magnet for the orientation, for example. By this step, the ferrite bond magnet  22  having the polar anisotropy is molded. 
     In step ST 13 , the molded ferrite bond magnet  22  is cooled down. 
     In step ST 14 , the ferrite bond magnet  22  is taken out of the second mold. 
     In step ST 15 , the ferrite bond magnet  22  taken out is demagnetized. 
     In step ST 16 , the ferrite bond magnet  22  is arranged in the first mold for injection molding of the rare-earth bond magnets  21 . 
     In step ST 17 , the plurality of groove parts  22   f  of the ferrite bond magnet  22  arranged in the first mold are filled in with the material of the rare-earth bond magnets  21 . The rare-earth bond magnets  21  are molded by injection molding, for example. 
     Incidentally, the method of molding the rare-earth bond magnets  21  is not limited to the injection molding. The rare-earth bond magnets  21  may be molded by a different molding method such as press molding. 
     In step ST 18 , each rare-earth bond magnet  21  having a predetermined shape is molded while the material of the rare-earth bond magnet  21  is oriented. In the step ST 18 , each rare-earth bond magnet  21  is molded while the material of the rare-earth bond magnet  21  is oriented in a state where a magnetic field having polar anisotropy is generated inside the first mold by using the magnet for the orientation, for example. By this step, the plurality of rare-earth bond magnets  21  having the polar anisotropy are molded. Namely, the rotor body  11  including the rare-earth bond magnets  21  and the ferrite bond magnet  22  integrally molded together is formed. When the rare-earth bond magnets  21  and the ferrite bond magnet  22  are integrally molded together, two bond magnets of types different from each other are fused to each other. By this process, the first overhang part  42  of the rare-earth bond magnet  21  is fixed to the end part  22   c  of the ferrite bond magnet  22  on the +z-axis side, and the second overhang part  43  of the rare-earth bond magnet  21  is fixed to the end part  22   d  of the ferrite bond magnet  22  on the −z-axis side. 
     In step ST 19 , the foamed rotor body  11  is cooled down. 
     In step ST 20 , the rotor body  11  is taken out of the first mold. 
     In step ST 21 , the rotor body  11  taken out is demagnetized. 
     Next, the manufacturing cost of the rotor body  11  according to the first embodiment will be described below while making a comparison with a rotor body  111  according to a comparative example.  FIG.  9    is a plan view showing the configuration of the rotor body  111  according to the comparative example. As shown in  FIG.  9   , in the rotor body  111  according to the comparative example, a rare-earth bond magnet  121  in a ring shape is arranged on the outer side of a ferrite bond magnet  122  in a ring shape. Namely, in the rotor body  111  according to the comparative example, the whole of an outer peripheral surface of the rotor body  111  is famed by an outer peripheral surface  121   a  of the rare-earth bond magnet  121 . 
     In contrast, in the first embodiment, the outer peripheral surface  11   a  of the rotor body  11  is formed by the outer peripheral surfaces  22   e  of the ferrite bond magnet  22  and the outer peripheral surfaces  21   c  of the rare-earth bond magnets  21 . With this configuration, in the rotor body  11  according to the first embodiment, the amount of the rare-earth bond magnet  21  can be reduced as compared to the rotor body  111  according to the comparative example. In the rotor  1  according to the first embodiment, the amount of the rare-earth bond magnet  21  can be reduced by approximately 20% as compared to the rotor according to the comparative example. The rare-earth bond magnet  21  is expensive as compared to the ferrite bond magnet  22 . For example, the material unit price of the rare-earth bond magnet is ten times or more of the material unit price of the ferrite bond magnet. Thus, the manufacturing cost of the rotor body  11  according to the first embodiment can be reduced. 
     Next, surface magnetic flux density of the rotor body  11  according to the first embodiment will be described below while making a comparison with the rotor body  111  according to the comparative example.  FIG.  10    is a graph showing a distribution of the surface magnetic flux density of the rotor body  11  according to the first embodiment and a distribution of the surface magnetic flux density of the rotor body  111  according to the comparative example. In  FIG.  10   , the horizontal axis represents the position [degree] in the circumferential direction R 1  on the outer peripheral surface of the rotor body  11  or the outer peripheral surface of the rotor body  111 , and the vertical axis represents the surface magnetic flux density [a.u.]. Further, in  FIG.  10   , the solid line indicates the distribution of the surface magnetic flux density of the rotor body  11  according to the first embodiment, and the broken line indicates the distribution of the surface magnetic flux density of the rotor body  111  according to the comparative example. 
     As shown in  FIG.  10   , the distribution of the surface magnetic flux density of the rotor body  111  according to the comparative example is represented by a waveform S 1  of an even sinusoidal wave. Meanwhile, the distribution of the surface magnetic flux density of the rotor body  11  according to the first embodiment is represented by a waveform S 2  of a substantially sinusoidal wave being approximately even. Namely, as compared to the rotor body  111  according to the comparative example, an abrupt change in the surface magnetic flux density in the circumferential direction R 1  is inhibited also in the rotor body  11  according to the first embodiment. Specifically, while magnetic flux density equivalent to that in the rotor body  111  according to the comparative example is obtained in a magnetic pole center (a north pole or a south pole) of the rotor body  11  according to the first embodiment, magnetic flux density slightly less than that in the rotor body  111  according to the comparative example is obtained in an inter-pole part (between a north pole and a south pole). However, the decrease in the magnetic flux density can be compensated for since the rotor body  11  according to the first embodiment includes the plurality of rare-earth bond magnets  21  even if the amount of the ferrite bond magnet  22  is smaller as compared to the rotor body  111  according to the comparative example. Accordingly, the rotor body  11  according to the first embodiment is capable of achieving inductive voltage equivalent to that of the rotor body  111  according to the comparative example. 
     As described above, with the rotor  1  according to the first embodiment, the first overhang part  42  of the rare-earth bond magnet  21  and the end part  22   c  of the ferrite bond magnet  22  on the +z-axis side are joined to each other. With this configuration, the joining area between the rare-earth bond magnet  21  and the ferrite bond magnet  22  increases, and thus the falling off of the rare-earth bond magnet  21  from the ferrite bond magnet  22  can be prevented. 
     Further, with the rotor  1  according to the first embodiment, the second overhang part  43  of the rare-earth bond magnet  21  and the end part  22   d  of the ferrite bond magnet  22  on the −z-axis side are joined to each other. With this configuration, the joining area between the rare-earth bond magnet  21  and the ferrite bond magnet  22  increases further, and thus the falling off of the rare-earth bond magnet  21  from the ferrite bond magnet  22  is further less likely to occur. 
     Furthermore, with the rotor  1  according to the first embodiment, the ferrite bond magnet  22  supported by the shaft  10  has the polar anisotropy. Accordingly, it is unnecessary to arrange the rotor core for foaming a magnetic path, on the inner side of the ferrite bond magnet  22  in the radial direction, and thus the number of components in the rotor  1  can be reduced and the weight of the rotor  1  can be reduced. 
     Moreover, with the rotor  1  according to the first embodiment, the outer peripheral surface of the rotor body  11  is formed by the outer peripheral surfaces  22   e  of the ferrite bond magnet  22  and the outer peripheral surfaces  21   c  of the rare-earth bond magnets  21 . The rare-earth bond magnet  21  is more expensive than the ferrite bond magnet  22 . In the rotor  1  according to the first embodiment, the amount of the rare-earth bond magnet  21  can be reduced, and thus the manufacturing cost of the rotor  1  can be reduced. 
     In addition, with the rotor  1  according to the first embodiment, the rotor  1  is capable of achieving inductive voltage equivalent to that of the rotor according to the comparative example since an abrupt change in the surface magnetic flux density of the rotor body  11  is inhibited even in the case where the amount of the rare-earth bond magnet  21  is reduced. Accordingly, the rotor  1  according to the first embodiment is capable of achieving high accuracy of rotation control equivalent to that of the rotor according to the comparative example. 
     Second Embodiment 
       FIG.  11    is a partial sectional view showing the configuration of a rotor body  211  of a rotor according to a second embodiment. In  FIG.  11   , components identical or corresponding to components shown in  FIG.  6    are assigned the same reference characters as in  FIG.  6   . The rotor body  211  according to the second embodiment differs from the rotor body  11  according to the first embodiment in that an overhang part is fitted with a concave part formed on a ferrite bond magnet  222 . 
     As shown in  FIG.  11   , the rotor body  211  includes a rare-earth bond magnet  221  and a ferrite bond magnet  222 . The ferrite bond magnet  222  includes a first concave part  222   h  famed on an end part  222   c  on the +z-axis side and a second concave part  222   i  formed on an end part  222   d  on the −z-axis side. Incidentally, the ferrite bond magnet  222  may also be configured to include only one of the first concave part  222   h  and the second concave part  222   i . Further, the ferrite bond magnet  222  may also be configured to include a plurality of first concave parts  222   h  or a plurality of second concave parts  222   i.    
     The rare-earth bond magnet  221  includes the pillar part  41 , a first overhang part  242  and a second overhang part  243 . The first overhang part  242  includes a convex part  242   b  as a first fitting part. The convex part  242   b  projects toward the ferrite bond magnet  222  from an end face  242   c  of the first overhang part  242  on the −z-axis side. The convex part  242   b is fitted in the first concave part  222   h.    
     The second overhang part  243  includes a convex part  243   b  as a second fitting part. The convex part  243   b  projects toward the ferrite bond magnet  222  from an end face  243   c  of the second overhang part  243  on the +z-axis side. The convex part  243   b is fitted in the second concave part  222   i.    
     In the ferrite bond magnet  222 , the length L 1  in the axial direction between the end part  222   c  on the +z-axis side and the end part  222   d  on the −z-axis side is greater than the length L 2  in the axial direction between a bottom surface  222   j  of the first concave part  222   h  and a bottom surface  222   k  of the second concave part  222   i.    
     With the rotor according to the second embodiment described above, the convex part  242   b  of the first overhang part  242  is fitted in the first concave part  222   h . With this configuration, the falling off of the rare-earth bond magnet  221  from the ferrite bond magnet  222  is further less likely to occur. 
     Further, with the rotor according to the second embodiment, the convex part  243   b  of the second overhang part  243  is fitted in the second concave part  222   i . With this configuration, the falling off of the rare-earth bond magnet  221  from the ferrite bond magnet  222  is further less likely to occur. 
     Modification of Second Embodiment 
       FIG.  12    is a partial sectional view showing the configuration of a rotor body  211 A of a rotor according to a modification of the second embodiment. In  FIG.  12   , components identical or corresponding to components shown in  FIG.  11    are assigned the same reference characters as in  FIG.  11   . The rotor body  211 A according to the modification of the second embodiment differs from the rotor body  11  according to the first embodiment in that an overhang part is fitted with a convex part formed on a ferrite bond magnet  222 A. 
     As shown in  FIG.  12   , the rotor body  211 A includes a rare-earth bond magnet  221 A and a ferrite bond magnet  222 A. The ferrite bond magnet  222 A includes a first convex part  222   m  famed on the end part  222   c  on the +z-axis side and a second convex part  222   n  formed on the end part  222   d  on the −z-axis side. A surface  222   u  of the first convex part  222   m  on the +z-axis side is flush with a surface of the ferrite bond magnet  222 A on the +z-axis side. A surface  222   v  of the second convex part  222   n  on the −z-axis side is flush with a surface of the ferrite bond magnet  222 A on the −z-axis side. Incidentally, the ferrite bond magnet  222 A may also be configured to include only one of the first convex part  222   m  and the second convex part  222   n . Further, the ferrite bond magnet  222 A may also be configured to include a plurality of first convex parts  222   m  or a plurality of second convex parts  222   n.    
     The rare-earth bond magnet  221 A includes the pillar part  41 , a first overhang part  242 A and a second overhang part  243 A. The first overhang part  242 A includes a through hole  242   e  as a first fitting part. The through hole  242   e is fitted on the first convex part  222   m . Incidentally, the first overhang part  242 A may include not only the through hole  242   e , but also a concave part fitted on the first convex part  222   m.    
     The second overhang part  243 A includes a through hole  243   e  as a second fitting part. The through hole  243   e is fitted on the second convex part  222   n . Incidentally, the second overhang part  243 A may include not only the through hole  243   e , but also a concave part fitted on the second convex part  222   n.    
     In the ferrite bond magnet  222 A, the length L 1  in the axial direction between the end part  222   c  on the +z-axis side and the end part  222   d  on the −z-axis side is less than the length L 3  in the axial direction between the surface  222   u  of the first convex part  222   m  on the +z-axis side and the surface  222   v  of the second convex part  222   n  on the −z-axis side. 
     With the rotor according to the modification of the second embodiment described above, the through hole  242   e  of the first overhang part  242 A is fitted on the first convex part  221 m of the ferrite bond magnet  222 A. With this configuration, the falling off of the rare-earth bond magnet  221 A from the ferrite bond magnet  222 A is further less likely to occur. 
     Further, with the rotor according to the modification of the second embodiment, the through hole  243   e  of the second overhang part  243 A is fitted on the second convex part  222   n  of the ferrite bond magnet  222 A. With this configuration, the falling off of the rare-earth bond magnet  221 A from the ferrite bond magnet  222 A is further less likely to occur. 
     Furthermore, with the rotor according to the modification of the second embodiment, the first overhang part  242 A and the second overhang part  243 A include the through holes  242   e  and  243   e . With this configuration, the amount of the rare-earth bond magnet  221 A in the rotor body  211 A is reduced, and thus the manufacturing cost of the rotor can be reduced. 
     Third Embodiment 
       FIG.  13    is a sectional view showing the configuration of a rotor body  311  of a rotor according to a third embodiment. In  FIG.  13   , components identical or corresponding to components shown in  FIG.  6    are assigned the same reference characters as in  FIG.  6   . The rotor body  311  according to the third embodiment differs from the rotor body  11  according to the first embodiment in that a step part is formed on a ferrite bond magnet  322 . 
     As shown in  FIG.  13   , the rotor body  311  of the rotor includes a rare-earth bond magnet  321  and a ferrite bond magnet  322 . The ferrite bond magnet  322  includes a first step part  322   p  famed on an end part  322   c  on the +z-axis side and a second step part  322   q  formed on an end part  322   d  on the −z-axis side. The first step part  322   p is recessed in the −z-axis direction from the end part  322   c  on the +z-axis side. The second step part  322   q is recessed in the +z-axis direction from the end part  322   d  on the −z-axis side. Incidentally, the ferrite bond magnet  322  may also be configured to include only one of the first step part  322   p  and the second step part  322   q.    
     The rare-earth bond magnet  321  includes a pillar part  341 , a first overhang part  342  and a second overhang part  343 . The length L 341  of the pillar part  341  in the axial direction is equal to the length L 22  of the ferrite bond magnet  322  in the axial direction. The first overhang part  342  is joined to a bottom surface  322   r  of the first step part  322   p . The second overhang part  343  is joined to a bottom surface  322   s  of the second step part  322   q . 
       FIG.  14    is a plan view showing the configuration of the ferrite bond magnet  322  according to the third embodiment. In  FIG.  14   , components identical or corresponding to components shown in  FIG.  4    are assigned the same reference characters as in  FIG.  4   . 
     As shown in  FIG.  14   , the ferrite bond magnet  322  includes a plurality of first step parts  322   p  arranged at intervals in the circumferential direction R 1 . The first step part  322   p is situated on the inner side in the radial direction relative to the groove part  22   f . The width of the first step part  322   p  in the circumferential direction R 1  decreases toward the inner side in the radial direction. The shape of the first step part  322   p  as viewed in the −z-axis direction is a substantially triangular shape. Namely, the shape of the first step part  322   p is the same as the shape of the first overhang part  342 . In other words, the shape of the first step part  322   p  corresponds to the shape of the first overhang part  342 . Incidentally, although not shown in the figure, the shape of the second step part  322   q  (see  FIG.  13   ) as viewed in the −z-axis direction is the same as the shape of the second overhang part  343 . 
     With the rotor according to the third embodiment described above, the first overhang part  342  of the rare-earth bond magnet  321  is joined to the bottom surface  322   r  of the first step part  322   p  famed on the ferrite bond magnet  322 . With this configuration, the falling off of the rare-earth bond magnet  321  from the ferrite bond magnet  322  can be prevented. 
     Further, with the rotor according to the third embodiment, the second overhang part  343  of the rare-earth bond magnet  321  is joined to the bottom surface  322   s  of the second step part  322   q  formed on the ferrite bond magnet  322 . With this configuration, the falling off of the rare-earth bond magnet  321  from the ferrite bond magnet  322  is further less likely to occur. 
     Furthermore, with the rotor according to the third embodiment, the length L 341  of the pillar part  341  of the rare-earth bond magnet  321  in the axial direction is equal to the length L 22  of the ferrite bond magnet  322  in the axial direction. With this configuration, in the rotor body  311  according to the third embodiment, the amount of the rare-earth bond magnet  321  can be reduced, and thus the manufacturing cost of the rotor can be reduced. 
     First Modification of Third Embodiment 
       FIG.  15    is a partial sectional view showing the configuration of a rotor body  311 A of a rotor according to a first modification of the third embodiment. In  FIG.  15   , components identical or corresponding to components shown in  FIG.  11  or  13    are assigned the same reference characters as in  FIG.  11  or  13   . The rotor body  311 A according to the first modification of the third embodiment differs from the rotor body  311  according to the third embodiment in that an overhang part is fitted with a concave part formed on a step part of a ferrite bond magnet  322 A. 
     As shown in  FIG.  15   , the rotor body  311 A includes a rare-earth bond magnet  321 A and a ferrite bond magnet  322 A. The ferrite bond magnet  322 A includes a first concave part  322   h  formed on the bottom surface  322   r  of the first step part  322   p  and a second concave part  322   i  formed on the bottom surface  322   s  of the second step part  322   q . Incidentally, the ferrite bond magnet  322 A may also be configured to include one of the first concave part  322   h  and the second concave part  322   i . Further, the ferrite bond magnet  322 A may also be configured to include a plurality of first concave parts  322   h  or a plurality of second concave parts  322   i.    
     The rare-earth bond magnet  321 A includes the pillar part  341 , a first overhang part  342 A and a second overhang part  343 A. The first overhang part  342 A includes a convex part  42   b  as a first fitting part. The convex part  42   b is fitted in the first concave part  322   h . The second overhang part  343 A includes a convex part  43   b  as a second fitting part. The convex part  43   b is fitted in the second concave part  322   i.    
     In the ferrite bond magnet  322 A, the length L 4  in the axial direction between the bottom surface  322   r  of the first step part  322   p  and the bottom surface  322   s  of the second step part  322   q is greater than the length L 5  in the axial direction between the bottom surface of the first concave part  322   h  and the bottom surface of the second concave part  322   i.    
     With the rotor according to the first modification of the third embodiment described above, the convex part  42   b  of the first overhang part  342 A is fitted in the first concave part  322   h  famed on the first step part  322   p  of the ferrite bond magnet  322 A. With this configuration, the falling off of the rare-earth bond magnet  321 A from the ferrite bond magnet  322 A is further less likely to occur. 
     Further, with the rotor according to the first modification of the third embodiment, the convex part  43   b  of the second overhang part  343 A is fitted in the second concave part  322   i  famed on the second step part  322   q  of the ferrite bond magnet  322 A. With this configuration, the falling off of the rare-earth bond magnet  321 A from the ferrite bond magnet  322 A is further less likely to occur. 
     Second Modification of Third Embodiment 
       FIG.  16    is a partial sectional view showing the configuration of a rotor body  311 B of a rotor according to a second modification of the third embodiment. In  FIG.  16   , components identical or corresponding to components shown in  FIG.  12  or  13    are assigned the same reference characters as in  FIG.  12  or  13   . The rotor body  311 B according to the second modification of the third embodiment differs from the rotor body  311  according to the third embodiment in that an overhang part is fitted with a convex part formed on a step part of a ferrite bond magnet  322 B. 
     As shown in  FIG.  16   , the rotor body  311 B includes a rare-earth bond magnet  321 B and a ferrite bond magnet  322 B. The ferrite bond magnet  322 B includes a first convex part  322   m  that projects toward the +z-axis side from the bottom surface  322   r  of the first step part  322   p  and a second convex part  322   n  that projects toward the −z-axis side from the bottom surface  322   s  of the second step part  322   q . A surface  322   u  of the first convex part  322   m  on the +z-axis side is flush with a surface of the ferrite bond magnet  322 B on the +z-axis side. A surface  322   v  of the second convex part  322   n  on the −z-axis side is flush with a surface of the ferrite bond magnet  322 B on the −z-axis side. Incidentally, the ferrite bond magnet  322 B may also be configured to include only one of the first convex part  322   m  and the second convex part  322   n . Further, the ferrite bond magnet  322 B may also be configured to include a plurality of first convex parts  322   m  or a plurality of second convex parts  322   n.    
     The rare-earth bond magnet  321 B includes the pillar part  341 , a first overhang part  342 B and a second overhang part  343 B. The first overhang part  342 B includes a through hole  342   e  as a first fitting part. The through hole  342   e is fitted on the first convex part  322   m . The second overhang part  343 B includes a through hole  343   e  as a second fitting part. The through hole  343   e is fitted on the second convex part  322   n.    
     In the ferrite bond magnet  322 B, the length L 4  in the axial direction between the bottom surface  322   r  of the first step part  322   p  and the bottom surface  322   s  of the second step part  322   q is less than the length L 6  in the axial direction between the surface  322   u  of the first convex part  322   m  on the +z-axis side and the surface  322   v  of the second convex part  322   n  on the −z-axis side. 
     With the rotor according to the second modification of the third embodiment described above, the through hole  342   e  of the first overhang part  342 B is fitted on the first convex part  322   m  formed on the first step part  322   p  of the ferrite bond magnet  322 B. With this configuration, the falling off of the rare-earth bond magnet  321 B from the ferrite bond magnet  322 B is further less likely to occur. 
     Further, with the rotor according to the second modification of the third embodiment, the through hole  343   e  of the second overhang part  343 B is fitted on the second convex part  322   n  famed on the second step part  322   q  of the ferrite bond magnet  322 B. With this configuration, the falling off of the rare-earth bond magnet  321 B from the ferrite bond magnet  322 B is further less likely to occur. 
     Fourth Embodiment 
       FIG.  17    (A) is an enlarged plan view showing the configuration of a rotor body  411  of a rotor according to a fourth embodiment.  FIG.  17 (B)  is an enlarged bottom view showing the configuration of the rotor body  411  of the rotor according to the fourth embodiment. In  FIGS.  17 (A) and  17 (B) , components identical or corresponding to components shown in  FIG.  4    are assigned the same reference characters as in  FIG.  4   . The rotor body  411  according to the fourth embodiment differs from the rotor body  11  according to the first embodiment in the shape of the overhang part. 
     As shown in  FIGS.  17 (A) and  17 (B) , the rotor body  411  of the rotor includes a rare-earth bond magnet  421  and the ferrite bond magnet  22 . The rare-earth bond magnet  421  includes the pillar part  41 , a first overhang part  442  extending inward in the radial direction from the end part  41   a  of the pillar part  41  on the +z-axis side, and a second overhang part  443  extending inward in the radial direction from the end part  41   b  of the pillar part  41  on the −z-axis side. 
     The length A 1  in the circumferential direction R 1  of the first overhang part  442  is greater than the length A 2  in the circumferential direction R 1  of the end part  41   a  of the pillar part  41  on the +z-axis side. The length A 3  in the circumferential direction R 1  of the second overhang part  443  is greater than the length A 4  in the circumferential direction R 1  of the end part  41   b  of the pillar part  41  on the −z-axis side. 
     Here, the “length in the circumferential direction R 1  of the first overhang part  442  (or the second overhang part  443 )” means the length of a straight line in the first overhang part  442  (or the second overhang part  443 ) extending in a direction orthogonal to a straight line M connecting the axis C 1  and the first overhang part  442 . Further, the “length in the circumferential direction R 1  of the end part  41   a  on the +z-axis side (or the end part  41   b  on the −z-axis side)” means the length of the shortest straight line among straight lines in the end part  41   a  on the +z-axis side (or the end part  41   b  on the −z-axis side) extending in the direction orthogonal to the straight line M connecting the axis C 1  and the pillar part  41 . 
     In the fourth embodiment, the length A 3  of the second overhang part  443  is the same as the length A 1  of the first overhang part  442 . Further, in the pillar part  41 , the length A 4  of the end part  41   b  on the −z-axis side is the same as the length A 2  of the end part  41   a  on the +z-axis side. 
     With the rotor according to the fourth embodiment described above, the length A 1  in the circumferential direction R 1  of the first overhang part  442  is greater than the length A 2  in the circumferential direction R 1  of the end part  41   a  of the pillar part  41  on the +z-axis side. With this configuration, the joining area between the first overhang part  442  and the end part  22   c  of the ferrite bond magnet  22  on the +z-axis side increases, and thus the falling off of the rare-earth bond magnet  421  from the ferrite bond magnet  22  is further less likely to occur. 
     Further, with the rotor according to the fourth embodiment, the length A 3  in the circumferential direction R 1  of the second overhang part  443  is greater than the length A 4  in the circumferential direction R 1  of the end part  41   b  of the pillar part  41  on the −z-axis side. With this configuration, the joining area between the second overhang part  443  and the end part  22   d  of the ferrite bond magnet  22  on the −z-axis side increases, and thus the falling off of the rare-earth bond magnet  421  from the ferrite bond magnet  22  is further less likely to occur. 
     First Modification of Fourth Embodiment 
       FIG.  18    is a side view showing the configuration of a rotor body  411 A of a rotor according to a first modification of the fourth embodiment.  FIG.  19 (A)  is an enlarged plan view showing the configuration of the rotor body  411 A of the rotor according to the first modification of the fourth embodiment.  FIG.  19 (B)  is an enlarged bottom view showing the configuration of the rotor body  411 A of the rotor according to the first modification of the fourth embodiment. The rotor body  411 A according to the first modification of the fourth embodiment differs from the rotor body  411  according to the fourth embodiment in the shape of a second overhang part. 
     As shown in  FIG.  18   , the rotor body  411 A includes a plurality of rare-earth bond magnets  421 A and a ferrite bond magnet  422 A. 
     As shown in  FIGS.  19 (A) and  19 (B) , the rare-earth bond magnet  421 A includes the pillar part  41 , a first overhang part  442 A extending inward in the radial direction from the end part  41   a  of the pillar part  41  on the +z-axis side, and a second overhang part  443 A extending inward in the radial direction from the end part  41   b  of the pillar part  41  on the −z-axis side. 
     In the first modification of the fourth embodiment, the length A 13  of the second overhang part  443 A differs from the length A 1  of the first overhang part  442 A. Specifically, the length A 13  of the second overhang part  443 A is greater than the length A 1  of the first overhang part  442 A. Namely, in the first modification of the fourth embodiment, the shapes of the first overhang part  442 A and the second overhang part  443 A differ from each other. Incidentally, it is sufficient that the length A 13  is less than the length A 1 . 
     Further, in the first modification of the fourth embodiment, in the pillar part  41 , the length Al 4  of the end part  41   b  on the −z-axis side differs from the length A 2  of the end part  41   a  on the +z-axis side. Namely, in the rare-earth bond magnet  421 , the length in the circumferential direction R 1  is not constant in the overhang parts on both sides in the axial direction. Specifically, in the pillar part  41 , the length Al 4  of the end part  41   b  on the −z-axis side is greater than the length A 2  of the end part  41   a  on the +z-axis side. Incidentally, it is sufficient that the length Al 4  is less than the length A 2 . 
     With the rotor according to the first modification of the fourth embodiment described above, the length A 13  of the second overhang part  443 A differs from the length A 1  of the first overhang part  442 A. With this configuration, the expansion amount (or the contraction amount) of the first overhang part  442 A and the expansion amount (or the contraction amount) of the second overhang part  443 A differ from each other. Accordingly, force with which the rare-earth bond magnet  421 A is fixed to the ferrite bond magnet  422 A is enhanced, and thus the falling off of the rare-earth bond magnet  421 A from the ferrite bond magnet  422 A is further less likely to occur. 
     Second Modification of Fourth Embodiment 
       FIG.  20    (A) is an enlarged plan view showing the configuration of a rotor body  411 B of a rotor according to a second modification of the fourth embodiment. In  FIG.  20 (A) , components identical or corresponding to components shown in  FIG.  4    are assigned the same reference characters as in  FIG.  4   . The rotor body  411 B according to the second modification of the fourth embodiment differs from the rotor body  11  according to the first embodiment in the shape of an overhang part. 
     As shown in  FIG.  20 (A) , the rotor body  411 B includes a rare-earth bond magnet  421 B and a ferrite bond magnet  422 B. The rare-earth bond magnet  421 B includes the pillar part  41  and a first overhang part  442 B extending inward in the radial direction from the end part  41   a  of the pillar part  41  on the +z-axis side. 
     The first overhang part  442 B includes a first part  442   e  extending toward one side in the circumferential direction R 1  from the end part  41   a  of the pillar part  41  on the +z-axis side and a second part  442   f  extending toward the other side in the circumferential direction R 1  from the end part  41   a  of the pillar part  41  on the +z-axis side. In the second modification of the fourth embodiment, the first part  442   e  and the second part  442   f  extend so that the distance between the first part  442   e  and the second part  442   f  in the circumferential direction R 1  increases. With this configuration, the length in the circumferential direction R 1  of the first overhang part  442 B is greater than the length A 2  (see  FIG.  17   ) in the circumferential direction R 1  of the end part  41   a  of the pillar part  41  on the +z-axis side. An end part  422   c  of the ferrite bond magnet  422 B on the +z-axis side is arranged between the first part  442   e  and the second part  442   f.    
       FIG.  20 (B)  is a sectional view of the rotor body  411 B shown in  FIG.  20 (A)  taken along the line A 20 -A 20 . In  FIG.  20 (B) , components identical or corresponding to components shown in  FIG.  15    are assigned the same reference characters as in  FIG.  15   . 
     As shown in  FIGS.  20 (A) and  20 (B) , the first part  442   e  includes a convex part  442   g  as a fitting part. The convex part  442   g is fitted in a concave part  422   h  formed on a step part  422   p  of the ferrite bond magnet  422 B. The second part  442   f  includes a convex part  442   h  as a fitting part. The convex part  442   h is fitted in a concave part (not shown) formed on the ferrite bond magnet  422 B. Incidentally, the first part  442   e  and the second part  442   f  may also be configured to include fitting parts (for example, through holes or concave parts) to be fitted on convex parts famed on the ferrite bond magnet  422 B. 
     Here, when rl represents the distance from the axis C 1  to an end part  422   v  of the step part  422   p  on the outer side in the radial direction and r 2  represents the distance from the axis C 1  to an end part  422 w of the step part  422   p  on the inner side in the radial direction, the distance rl is longer than the distance r 2 . 
     With the rotor according to the second modification of the fourth embodiment described above, the first overhang part  442 B includes the first part  442   e  and the second part  442   f  extending toward both sides in the circumferential direction from the end part  41   a  of the pillar part  41  on the +z-axis side, and the ferrite bond magnet  422 B is arranged between the first part  442   e  and the second part  442   f . With this configuration, the falling off of the rare-earth bond magnet  421 B can be prevented while reducing the amount of the rare-earth bond magnet  421 B in the rotor body  411 B. Further, in the case where fitting parts fitted with the ferrite bond magnet  422 B are provided on both sides of the first overhang part  442 B in the circumferential direction, a part (i.e., a central part in the circumferential direction) of the rare-earth bond magnet  421 B unnecessary for the joining with the ferrite bond magnet  422 B can be reduced. 
     Fifth Embodiment 
       FIG.  21    is a plan view showing the configuration of a rotor body  511  of a rotor according to a fifth embodiment.  FIG.  22    is a sectional view of the rotor body  511  shown in  FIG.  21    taken along the line A 22 -A 22 . In  FIGS.  21  and  22   , components identical or corresponding to components shown in  FIG.  1  or  6    are assigned the same reference characters as in  FIG.  1  or  6   . The rotor body  511  according to the fifth embodiment differs from the rotor body  11  according to the first embodiment in the configuration of a rare-earth bond magnet  521 . 
     As shown in  FIGS.  21  and  22   , the rotor body  511  includes a rare-earth bond magnet  521  and a ferrite bond magnet  522 . The rare-earth bond magnet  521  includes a plurality of pillar parts  41  arranged at intervals in the circumferential direction R 1  and ring parts  551  and  552  situated on the inner side in the radial direction relative to the plurality of pillar parts  41 . The ring part  551  is joined to the end part  22   c  of the ferrite bond magnet  522  on the +z-axis side. The ring part  551  is formed of a plurality of first overhang parts  42  and a connection part  44  connecting the plurality of first overhang parts  42  adjoining in the circumferential direction. The ring part  552  is joined to the end part  22   d  of the ferrite bond magnet  522  on the −z-axis side. The ring part  552  is formed of a plurality of second overhang parts  43  and a connection part (not shown) connecting the plurality of second overhang parts  43  adjoining in the circumferential direction. Incidentally, the rare-earth bond magnet  521  may also be configured to include only one of the ring part  551  on the +z-axis side and the ring part  552  on the −z-axis side. 
     With the rotor according to the fifth embodiment described above, the rare-earth bond magnet  521  includes the ring part  551  including the connection part  44  connecting the plurality of first overhang parts  42  adjoining in the circumferential direction R 1 . With this configuration, the falling off of the rare-earth bond magnet  521  from the ferrite bond magnet  522  is further less likely to occur. 
     Further, with the rotor according to the fifth embodiment, the rare-earth bond magnet  521  further includes the ring part  552  including the connection part connecting the plurality of second overhang parts  43  adjoining in the circumferential direction R 1 . With this configuration, the falling off of the rare-earth bond magnet  521  from the ferrite bond magnet  522  is further less likely to occur. 
     Modification of Fifth Embodiment 
       FIG.  23    is a sectional view showing the configuration of a rotor body  511 A of a rotor according to a modification of the fifth embodiment.  FIG.  24    is a plan view showing the configuration of a ferrite bond magnet  522 A according to the modification of the fifth embodiment. In  FIGS.  23  and  24   , components identical or corresponding to components shown in  FIG.  21  or  22    are assigned the same reference characters as in  FIG.  21  or  22   . The rotor body  511 A according to the modification of the fifth embodiment differs from the rotor body  511  according to the fifth embodiment in that the ring parts  551  and  552  are respectively arranged in ring-shaped concave parts  522   r  and  522   s  of the ferrite bond magnet  522 A. 
     As shown in  FIG.  23   , the rotor body  511 A includes a rare-earth bond magnet  521 A and a ferrite bond magnet  522 A. The ring part  551  of the rare-earth bond magnet  521 A is arranged in the ring-shaped concave part  522   r  as a concave part formed on the end part  22   c  of the ferrite bond magnet  522 A on the +z-axis side. An end face of the ring part  551  on the +z-axis side is flush with an end face of the ferrite bond magnet  522 A on the +z-axis side. The ring part  552  is arranged in the ring-shaped concave part  522   s  formed on the end part  22   d  of the ferrite bond magnet  522 A on the −z-axis side. An end face of the ring part  552  on the −z-axis side is flush with an end face of the ferrite bond magnet  522 A on the −z-axis side. 
     As shown in  FIG.  24   , in the end part  22   c  of the ferrite bond magnet  522 A on the +z-axis side, the ring-shaped concave part  522   r  is situated on the inner side in the radial direction relative to the groove parts  22   f . The shape of the ring-shaped concave part  522   r  as viewed in the −z-axis direction is a ring shape about the axis C 1 . 
     With the rotor according to the modification of the fifth embodiment described above, the ferrite bond magnet  522 A includes the ring-shaped concave parts  522   r  and  522   s  in which the ring parts  551  and  552  are arranged. With this configuration, the amount of the rare-earth bond magnet  521 A in the rotor body  511 A is reduced, and thus the manufacturing cost of the rotor can be reduced. 
     Sixth Embodiment 
       FIG.  25    is a plan view showing the configuration of a rotor  6  according to a sixth embodiment.  FIG.  26    is a sectional view of the rotor  6  shown in  FIG.  25    taken along the line A 26 -A 26 . In  FIGS.  25  and  26   , components identical or corresponding to components shown in  FIG.  13    are assigned the same reference characters as in  FIG.  13   . The rotor  6  according to the sixth embodiment differs from the rotor according to any one of the first to fifth embodiments in that the rotor  6  includes ring members  661  and  662 . Incidentally, the rotor  6  will be described below with reference to  FIGS.  25  and  26    by using an example in which the rotor  6  includes the rotor body  311  according to the third embodiment. 
     As shown in  FIGS.  25  and  26   , the rotor  6  includes the shaft  10 , the rotor body  311 , the connection part  12 , and the ring members  661  and  662 . Each of the ring members  661  and  662  is a member having a ring shape about the axis C 1 . The ring members  661  and  662  are formed of a resin such as unsaturated polyester resin, for example. 
     The ring member  661  is situated on the +z-axis side relative to the rotor body  311 . The ring member  661  is fixed to an end face  342   f  of the first overhang part  342  on the +z-axis side and the end face  322   c  of the ferrite bond magnet  322  on the +z-axis side. Namely, when the rotor  6  is viewed in the −z-axis direction, the ring member  661  is arranged at a position overlapping with an interface surface of the first overhang part  342  and the ferrite bond magnet  322 . 
     The ring member  662  is situated on the −z-axis side relative to the rotor body  311 . The ring member  662  is fixed to an end face  343   f  of the second overhang part  343  on the −z-axis side and the end face  322   d  of the ferrite bond magnet  322  on the −z-axis side. Namely, when the rotor  6  is viewed in the +z-axis direction, the ring member  662  is arranged at a position overlapping with an interface surface of the second overhang part  343  and the ferrite bond magnet  322 . Incidentally, the rotor  6  may also be configured to include only one of the ring member  661  on the +z-axis side and the ring member  662  on the −z-axis side. 
     With the rotor  6  according to the sixth embodiment described above, on the +z-axis side of the rotor body  311 , the ring member  661  is fixed to the first overhang part  342  and the ferrite bond magnet  322 . With this configuration, the falling off of the rare-earth bond magnet  321  from the ferrite bond magnet  322  is further less likely to occur. 
     Further, with the rotor  6  according to the sixth embodiment, on the −z-axis side of the rotor body  311 , the ring member  662  is fixed to the second overhang part  343  and the ferrite bond magnet  322 . With this configuration, the falling off of the rare-earth bond magnet  321  from the ferrite bond magnet  322  is further less likely to occur. 
     Modification of Sixth Embodiment 
       FIG.  27    is a plan view showing the configuration of a rotor  6 A according to a modification of the sixth embodiment.  FIG.  28    is a sectional view of the rotor  6 A shown in  FIG.  27    taken along the line A 28 -A 28 . The rotor  6 A according to the modification of the sixth embodiment differs from the rotor  6  according to the sixth embodiment in that the ring members  661  and  662  are integrated with the connection part  12 . 
     As shown in  FIGS.  27  and  28   , the rotor  6 A includes the shaft  10 , the rotor body  311 , the ring members  661  and  662  as a first resin part, and the connection part  12  as a second resin part. The ring members  661  and  662  are connected to the connection part  12  by the integral molding of the ring members  661  and  662  and the connection part  12 . Specifically, the ring members  661  and  662  are connected to the ribs  12   c  of the connection part  12 . Namely, in the modification of the sixth embodiment, the shaft  10  and the rotor body  311  are connected to each other via the connection part  12  and the ring members  661  and  662 . 
     With the rotor  6 A according to the modification of the sixth embodiment described above, the ring members  661  and  662  are connected to the connection part  12 . With this configuration, when the shaft  10  and the rotor body  11  are integrally molded together via the connection part  12  formed of a resin, the ring members  661  and  662  can also be molded at the same time, and thus manufacturing steps of the rotor  6  can be reduced. 
     Here, the natural frequency of the rotor  6 A changes depending on the rigidity of the rotor  6 A. The rigidity of the rotor  6 A can be adjusted by changing the width and the length of each rib  12   c  and the number of ribs  12   c . In the modification of the sixth embodiment, the length of the rib is increased since the ribs  12   c  are connected to ring members  661  and  662 . Thus, the rigidity of the rotor  6 A is changed and the natural frequency of the rotor  6 A is changed. With this configuration, the occurrence of resonance can be inhibited and vibrational characteristics of the rotor  6 A can be adjusted. 
     Further, the inertia moment of the rotor  6 A changes depending on the mass of the rotor  6 A. The mass of the rotor  6 A can be adjusted by changing the width and the length of each rib  12   c  and the number of ribs  12   c . In the modification of the sixth embodiment, as the inertia moment increases, higher starting torque is needed, but the rotation of the rotor  6 A can be more stabilized. Namely, in the modification of the sixth embodiment, the ribs  12   c  are connected to the ring members  661  and  662 , and thus the natural frequency and the inertia moment of the rotor  6 A can be adjusted by changing the shape of each rib  12   c . Incidentally, the natural frequency and the inertia moment of the rotor  6 A may also be changed by changing the number of ribs  12   c.    
     Seventh Embodiment 
       FIG.  29    is a side view showing the configuration of a rotor body  711  of a rotor according to a seventh embodiment.  FIG.  30    is a sectional view showing the configuration of the rotor body  711  according to the seventh embodiment. The rotor body  711  according to the seventh embodiment differs from the rotor body according to any one of the first to sixth embodiments in that an overhang part is provided on a ferrite bond magnet  721 . 
     As shown in  FIG.  29   , the rotor body  711  includes a ferrite bond magnet  721  as a first permanent magnet and a plurality of rare-earth bond magnets  722  as second permanent magnets. The plurality of rare-earth bond magnets  722  are arranged at intervals in the circumferential direction R 1 . 
     The ferrite bond magnet  721  includes a cylinder part  71 , a first overhang part  72  and a second overhang part  73 . The cylinder part  71  is supported by the shaft  10  (see  FIG.  1   ) via the connection part  12  (see  FIG.  2   ). The length L 71  of the cylinder part  71  in the axial direction is greater than the length L 72  of the rare-earth bond magnet  722  in the axial direction. 
     The first overhang part  72  extends outward in the radial direction from an end part  71   a  of the cylinder part  71  on the +z-axis side. The first overhang part  72  is in contact with an end part  722   c  of the rare-earth bond magnet  722  on the +z-axis side. The second overhang part  73  extends outward in the radial direction from an end part  71   b  of the cylinder part  71  on the −z-axis side. The second overhang part  73  is in contact with an end part  722   d  of the rare-earth bond magnet  722  on the −z-axis side. An end part of the first overhang part  72  on the outer side in the radial direction and an end part of the second overhang part  73  on the outer side in the radial direction are flush with an outer peripheral surface of the rare-earth bond magnet  722 . With this configuration, the first overhang part  72  and the second overhang part  73  get closer to the stator in the radial direction, and thus the magnetic flux flowing into the stator can be increased. 
     In the seventh embodiment, the cylinder part  71  and the rare-earth bond magnets  722  are joined to each other by the integral molding of the ferrite bond magnet  721  and the rare-earth bond magnets  722 . Incidentally, in the seventh embodiment, the integral molding of the ferrite bond magnet  721  and the rare-earth bond magnets  722  means integrating the ferrite bond magnet  721  and the rare-earth bond magnets  722  together by molding the ferrite bond magnet  721  in a state where the rare-earth bond magnets  722  manufactured previously is arranged in a mold. 
     Further, in the seventh embodiment, the first overhang part  72  and the end part  722   c  of the rare-earth bond magnet  722  on the +z-axis side are joined to each other and the second overhang part  73  and the end part  722   d  of the rare-earth bond magnet  722  on the −z-axis side are joined to each other. As above, in the seventh embodiment, the ferrite bond magnet  721  and the rare-earth bond magnet  722  are joined to each other in the axial direction, and thus the joining area between the ferrite bond magnet  721  and the rare-earth bond magnet  722  can be increased. Accordingly, the falling off of the rare-earth bond magnet  722  from the ferrite bond magnet  721  can be prevented. 
     Next, a process for forming the rotor body  711  will be described below by using  FIG.  31   .  FIG.  31    is a flowchart showing the process for forming the rotor body  711 . 
     In step ST 71 , the inside of a first mold for the injection molding of the rare-earth bond magnet  722  is filled in with the material of the rare-earth bond magnet  722 . 
     In step ST 72 , the rare-earth bond magnet  722  having a predetermined shape is molded while the material of the rare-earth bond magnet  722  is oriented. In the step ST 72 , the rare-earth bond magnet  722  is molded while the material of the rare-earth bond magnet  722  is oriented in a state where a magnetic field having polar anisotropy is generated inside the first mold by using the magnet for the orientation, for example. By this step, the rare-earth bond magnet  722  having polar anisotropy orientation is molded. 
     In step ST 73 , the molded rare-earth bond magnet  722  is cooled down. 
     In step ST 74 , the rare-earth bond magnet  722  is taken out of the first mold. 
     In step ST 75 , the rare-earth bond magnet  722  taken out is demagnetized. 
     In step ST 76 , the rare-earth bond magnets  722  are arranged in a second mold. 
     In step ST 77 , the inside of the second mold is filled in with the material of the ferrite bond magnet  721 . 
     In step ST 78 , the ferrite bond magnet  721  having a predetermined shape is molded while the material of the ferrite bond magnet  721  is oriented. In the step ST 78 , the ferrite bond magnet  721  is molded while the material of the ferrite bond magnet  721  is oriented in a state where a magnetic field having polar anisotropy is generated inside the second mold by using the magnet for the orientation, for example. 
     Steps ST 79  to ST 81  are the same as the steps ST 19  to ST 21  shown in  FIG.  8   . 
     With the rotor according to the seventh embodiment described above, the first overhang part  72  of the ferrite bond magnet  721  is joined to the end part  722   c  of the rare-earth bond magnet  722  on the +z-axis side. With this configuration, the joining area between the rare-earth bond magnet  722  and the ferrite bond magnet  721  increases, and thus the falling off of the rare-earth bond magnet  722  from the ferrite bond magnet  721  can be prevented. 
     Further, with the rotor according to the seventh embodiment, the second overhang part  73  of the ferrite bond magnet  721  is joined to the end part  722   d  of the rare-earth bond magnet  722  on the −z-axis side. With this configuration, the joining area between the rare-earth bond magnet  722  and the ferrite bond magnet  721  increases further, and thus the falling off of the rare-earth bond magnet  722  from the ferrite bond magnet  721  is further less likely to occur. 
     Furthermore, with the rotor according to the seventh embodiment, the ferrite bond magnet  721  is provided with the overhang parts (i.e., the first overhang parts  72  and the second overhang parts  73 ) for preventing the falling off of the rare-earth bond magnets  722 . With this configuration, the length in the axial direction of the rare-earth bond magnet  722  is reduced as compared to the length in the axial direction of the rare-earth bond magnet  21  according to the first embodiment, and thus the amount of the rare-earth bond magnet  722  can be reduced. Accordingly, the manufacturing cost of the rotor can be reduced. 
     First Modification of Seventh Embodiment 
       FIG.  32    is a partial sectional view showing the configuration of a rotor body  711 A of a rotor according to a first modification of the seventh embodiment. In  FIG.  32   , components identical or corresponding to components shown in  FIG.  30    are assigned the same reference characters as in  FIG.  30   . The rotor body  711 A according to the first modification of the seventh embodiment differs from the rotor body  711  according to the seventh embodiment in that an overhang part is fitted with a concave part formed on the rare-earth bond magnet. 
     As shown in  FIG.  32   , the rotor body  711 A of the rotor includes a ferrite bond magnet  721 A and a rare-earth bond magnet  722 A. The rare-earth bond magnet  722 A includes a first concave part  722   h  formed on the end part  722   c  on the +z-axis side and a second concave part  722   i  formed on the end part  722   d  on the −z-axis side. Incidentally, the rare-earth bond magnet  722 A may also be configured to include only one of the first concave part  722   h  and the second concave part  722   i . Further, the rare-earth bond magnet  722 A may also be configured to include a plurality of first concave parts  722   h  or a plurality of second concave parts  722   i.    
     The ferrite bond magnet  721 A includes the cylinder part  71 , a first overhang part  72 A and a second overhang part  73 A. The first overhang part  72 A includes a convex part  72   c  as a first fitting part. The convex part  72   c  projects toward the rare-earth bond magnet  722 A from an end face of the first overhang part  72 A on the −z-axis side. The convex part  72   c is fitted in the first concave part  722   h.    
     The second overhang part  73 A includes a convex part  73   c  as a second fitting part. The convex part  73   c  projects toward the rare-earth bond magnet  722 A from an end face of the second overhang part  73 A on the +z-axis side. The convex part  73   c is fitted in the second concave part  722   i.    
     In the rare-earth bond magnet  722 A, the length L 7  in the axial direction between the end part  722   c  on the +z-axis side and the end part  722   d  on the −z-axis side is greater than the length L 8  in the axial direction between a bottom surface  722   j  of the first concave part  722   h  and a bottom surface  722   k  of the second concave part  722   i.    
     With the rotor according to the first modification of the seventh embodiment described above, the convex part  72   c  of the first overhang part  72 A is fitted in the first concave part  722   h . formed on the rare-earth bond magnet  722 A. With this configuration, the falling off of the rare-earth bond magnet  722 A from the ferrite bond magnet  721 A is further less likely to occur. 
     Further, with the rotor according to the first modification of the seventh embodiment, the convex part  73   c  of the second overhang part  73 A is fitted in the second concave part  722   i  famed on the end part  722   d  on the −z-axis side. With this configuration, the falling off of the rare-earth bond magnet  722 A from the ferrite bond magnet  721 A is further less likely to occur. 
     Second Modification of Seventh Embodiment 
       FIG.  33    is a partial sectional view showing the configuration of a rotor body  711 B of a rotor according to a second modification of the seventh embodiment. In  FIG.  33   , components identical or corresponding to components shown in  FIG.  30    are assigned the same reference characters as in  FIG.  30   . The rotor body  711 B according to the second modification of the seventh embodiment differs from the rotor body  711  according to the seventh embodiment in that an overhang part is fitted with a convex part formed on the rare-earth bond magnet. 
     As shown in  FIG.  33   , the rotor body  711 B includes a ferrite bond magnet  721 B and a rare-earth bond magnet  722 B. The rare-earth bond magnet  722 B includes a first convex part  722   m  projecting toward the +z-axis side from the end part  722   c  on the +z-axis side and a second convex part  722   n  projecting toward the −z-axis side from the end part  722   d  on the −z-axis side. Incidentally, the rare-earth bond magnet  722 B may also be configured to include only one of the first convex part  722   m  and the second convex part  722   n . Further, the rare-earth bond magnet  722 B may also be configured to include a plurality of first convex parts  722   m  or a plurality of second convex parts  722   n.    
     The ferrite bond magnet  721 B includes the cylinder part  71 , a first overhang part  72 B and a second overhang part  73 B. The first overhang part  72 B includes a through hole  72   e  as a first fitting part. The through hole  72   e is fitted on the first convex part  722   m . Incidentally, the first overhang part  72 B may also be configured to include a concave part to be fitted on the first convex part  722   m  instead of the through hole  72   e.    
     The second overhang part  73 B includes a through hole  73   e  as a second fitting part. The through hole  73   e is fitted on the second convex part  722   n . Incidentally, the second overhang part  73 B may also be configured to include a concave part to be fitted on the second convex part  722   n  instead of the through hole  73   e.    
     In the rare-earth bond magnet  722 B, the length L 7  in the axial direction between the end part  722   c  on the +z-axis side and the end part  722   d  on the −z-axis side is less than the length L 9  in the axial direction between the tip end surface  222   j  of the first convex part  222   m  and the tip end surface  222   k  of the second convex part  222   n.    
     With the rotor according to the second modification of the seventh embodiment described above, the through hole  72   e  of the first overhang part  72 B is fitted on the first convex part  722   m  of the rare-earth bond magnet  722 B. With this configuration, the falling off of the rare-earth bond magnet  722 B from the ferrite bond magnet  721 B is further less likely to occur. 
     Further, with the rotor according to the second modification of the seventh embodiment, the through hole  73   e  of the second overhang part  73 B is fitted on the second convex part  722   n  of the rare-earth bond magnet  722 B. With this configuration, the falling off of the rare-earth bond magnet  722 B from the ferrite bond magnet  721 B is further less likely to occur. 
     Third Modification of Seventh Embodiment 
       FIG.  34 (A)  is a sectional view showing the configuration of a rotor body  711 C of a rotor according to a third modification of the seventh embodiment.  FIG.  34 (B)  is another sectional view showing the configuration of the rotor body  711 C of the rotor according to the third modification of the seventh embodiment. The rotor body  711 C according to the third modification of the seventh embodiment differs from the rotor body  711  according to the seventh embodiment in that a plurality of rare-earth bond magnets are connected together. 
     As shown in  FIGS.  34 (A) and  34 (B) , the rotor body  711 C includes a ferrite bond magnet  721  and a rare-earth bond magnet  722 . The rare-earth bond magnet  722  includes a plurality of pillar parts  741  arranged at intervals in the circumferential direction R 1  and a connection part  751  connecting the plurality of pillar parts  741  together. The outer diameter D 72  of the ferrite bond magnet  721  is greater than the outer diameter D 75  of the connection part  751 . The connection part  751  is arranged between the end part  722   c  of the rare-earth bond magnet  722  on the +z-axis side and the end part  722   d  of the rare-earth bond magnet  722  on the −z-axis side. In the third modification of the seventh embodiment, the connection part  751  is arranged at a central part of the rare-earth bond magnet  722  in the axial direction. 
     With the rotor according to the third modification of the seventh embodiment described above, the rare-earth bond magnet  722  of the rotor body  711  includes the connection part  751  connecting the plurality of pillar parts  741  together. With this configuration, the falling off of the rare-earth bond magnet  722  from the ferrite bond magnet  721  during the rotation is further less likely to occur. 
     Eighth Embodiment 
     Next, a motor  80  including the rotor according to any one of the above-described first to seventh embodiments will be described below.  FIG.  35    is a configuration diagram showing a partial cross section and a side face of the motor  80  according to an eighth embodiment. As shown in  FIG.  35   , the motor  80  includes a stator  81  and a rotor  82 . The motor  80  is a permanent magnet synchronous motor, for example. 
     The stator  81  includes a stator core  81   a  and a mold resin part  81   b  that covers the stator core  81   a . A coil  81   d  is wound around the stator core  81   a  via an insulator  81   c . The mold resin part  81   b is famed of a thermosetting resin such as BMC (Bulk Molding Compound) resin, for example. 
     The rotor  82  is arranged on the inner side of the stator  81  in the radial direction. Namely, the motor  80  is a motor of the inner rotor type. The rotor according to any one of the first to seventh embodiments can be employed as the rotor  82 . The shaft  10  of the rotor  82  is rotatably supported by bearings  83  and  84 . 
     The rotor  82  is provided with a sensor magnet  85 . The sensor magnet  85  faces a circuit board  86 . A magnetic field of the sensor magnet  85  is detected by a magnetic sensor  87  provided on the circuit board  86 , by which a rotational position of the rotor is detected. 
     In the rotor according to any one of the first to seventh embodiments, the falling off of the rare-earth bond magnet arranged on the outer side is prevented, and thus the quality of the rotor can be improved. Accordingly, the quality of the motor including the rotor can also be improved. 
     Ninth Embodiment 
       FIG.  36    is a diagram schematically showing the configuration of an air conditioner  90  according to a ninth embodiment. As shown in  FIG.  36   , the air conditioner  90  includes an indoor unit  91  and an outdoor unit  95  connected to the indoor unit  91  via a refrigerant pipe  94 . The air conditioner  90  is capable of executing an operation such as a cooling operation in which the indoor unit  91  blows out cool air or a heating operation in which the indoor unit  91  blows out warm air, for example. 
     The indoor unit  91  includes an indoor blower  92  as a blower and a housing  93  that covers the indoor blower  92 . The indoor blower  92  includes the motor  80  and an impeller  92   a  fixed to the shaft of the motor  80 . The impeller  92   a is driven by the motor  80 , by which an airflow is generated. The impeller  92   a is a cross-flow fan, for example. 
     The outdoor unit  95  includes an outdoor blower  96  as a blower, a compressor  97 , and a housing  98  that covers the outdoor blower  96  and the compressor  97 . The outdoor blower  96  includes the motor  80  and an impeller  96   a  fixed to the shaft of the motor  80 . The impeller  96   a  is driven by the motor  80 , by which an airflow is generated. The impeller  96   a  is a propeller fan, for example. The compressor  97  includes a motor  97   a  and a compression mechanism  97   b  driven by the motor  97   a.    
     As described above, in the air conditioner  90  according to the ninth embodiment, the motor  80  according to the eighth embodiment is applied to the indoor blower  92  and the outdoor blower  96 , for example. In the motor  80  according to the eighth embodiment, the falling off of the rare-earth bond magnet in the rotor is prevented as described earlier, and thus the quality of the motor  80  is improved. Accordingly, the quality of the indoor blower  92  and the outdoor blower  96  is also improved. Further, the quality of the air conditioner  90  including the indoor blower  92  and the outdoor blower  96  is also improved. Incidentally, the motor  80  may also be provided in only one of the indoor blower  92  and the outdoor blower  96 . Further, the motor  80  may also be applied to the motor  97   a  of the compressor  97 . Furthermore, the motor  80  according to the eighth embodiment may also be installed in equipment other than the air conditioner  90 .