Patent Publication Number: US-2018041080-A1

Title: Rotor, rotary electric machine, and method for manufacturing rotor

Description:
TECHNICAL FIELD 
     The present invention relates to: a rotor; a rotary electric machine; and a method for manufacturing the rotor, which can reduce displacement of magnets, thereby to suppress decrease in torque, increase in stress applied to a rotor core, and increase in rotation pressure balance. 
     BACKGROUND ART 
     In recent years, rotary electric machines used as electric motors or electric generators are required to have small sizes, high speeds, and high outputs. As a method for realizing a rotary electric machine having a small size, high speed, and high output, there is a method in which, with magnets embedded in the rotor, reluctance torque is utilized and combined with magnet torque caused by the magnets, thereby to increase generated torque. However, when a rotary electric machine having a small size and high speed is to be realized, there is a problem that stress due to centrifugal force of the rotor core becomes large, which could cause breakage of the rotor core or the magnets. 
     In contrast to this, as described in Patent Document 1, for example, there is a rotary electric machine in which magnets inserted in the rotor core are held by protrusions, whereby rotational centrifugal force of the magnets is reduced and stress occurring in the rotor core is reduced. 
     CITATION LIST 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2014-100048 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     Although such a conventional rotary electric machine has a shape in which magnets embedded in the rotor core are held by protrusions, the insertion accuracy at the time of inserting the magnets into the rotor core, and the positional accuracy of the magnets are not taken into consideration. Thus, the conventional rotary electric machine has a problem that decrease in torque, increase in stress applied to the rotor core, and increase in rotation imbalance occur. 
     The present invention has been made in order to solve the above-described problem. An object of the present invention is to provide a rotor, a rotary electric machine, and a method for manufacturing the rotor which reduce displacement of magnets thereby to prevent decrease in torque and increase in stress applied to the rotor core. 
     Solution to the Problems 
     A rotor of the present invention includes: 
     a rotor core in which a plurality of insertion holes each penetrating the rotor core in an axial direction are formed with intervals interposed thereamong in a circumferential direction; and 
     magnets respectively provided in the insertion holes, wherein 
     a hole-inside-peripheral-surface of each insertion hole does not contact with a magnet-inside-peripheral-surface of a corresponding one of the magnets, 
     a hole-outside-peripheral-surface of the insertion hole and a magnet-outside-peripheral-surface of the magnet contact with each other at two locations of a first location and a second location, 
     an adhesive layer portion is formed between the first location and the second location and between the hole-outside-peripheral-surface of the insertion hole and the magnet-outside-peripheral-surface of the magnet, and 
     a first protruding portion which protrudes toward outside in a radial direction is formed at the hole-inside-peripheral-surface of the insertion hole, and the first protruding portion contacts with a circumferential-direction-side peripheral surface of the magnet. 
     A rotary electric machine of the present invention includes: 
     the rotor described above; 
     a rotation shaft for rotating the rotor core; and 
     a stator having a coil, and disposed with an air gap interposed between the stator and the rotor. 
     A method for manufacturing the rotor described above of the present invention includes: 
     a step of applying an adhesive agent to the magnet-outside-peripheral-surface of the magnet; 
     a step of inserting the magnet into the insertion hole; 
     a step of pressing the magnet-outside-peripheral-surface of the magnet and the hole-outside-peripheral-surface of the insertion hole against each other; 
     a step of pressing the circumferential-direction-side peripheral surface of the magnet against the first protruding portion; and 
     a step of forming the adhesive layer portion by causing the adhesive agent to be hardened with the rotor core being rotated. 
     A method for manufacturing for the rotor described above of the present invention includes: 
     a step of applying an adhesive agent to the magnet-outside-peripheral-surface of the magnet, 
     a step of inserting the magnet into the insertion hole; 
     a step of pressing the magnet-outside-peripheral-surface of the magnet and the hole-outside-peripheral-surface of the insertion hole against each other; and 
     a step of forming the adhesive layer portion, by pressing the circumferential-direction-side peripheral surface of the magnet against the first protruding portion and causing the adhesive agent to be hardened, with the rotor core being rotated. 
     Effect of the Invention 
     According to the rotor, the rotary electric machine, and the method for manufacturing the rotor of the present invention, displacement of the magnets can be reduced, and decrease in torque, increase in stress applied to the rotor core, and increase in rotation pressure balance can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing a configuration of a rotor of embodiment 1 of the present invention. 
         FIG. 2  is a partial enlarged plan view showing a configuration of the rotor shown in  FIG. 1 . 
         FIG. 3  is a perspective view showing a configuration of a rotary electric machine using the rotor shown in  FIG. 1 . 
         FIG. 4  is a plan view showing a configuration of the rotary electric machine shown in  FIG. 3 . 
         FIG. 5  is a flow chart for describing a method for manufacturing the rotor shown in  FIG. 1 . 
         FIG. 6  is a partial enlarged plan view showing a manufacturing step for the rotor shown in  FIG. 1 . 
         FIG. 7  is a partial enlarged plan view showing a manufacturing step for the rotor shown in  FIG. 1 . 
         FIG. 8  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 1 . 
         FIG. 9  is a partial enlarged plan view for describing a state after centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 1 . 
         FIG. 10  is a diagram showing the difference in torque between the rotary electric machine of the present invention and a rotary electric machine of a comparative example. 
         FIG. 11  is a plan view showing a configuration of a rotor of embodiment 2 of the present invention. 
         FIG. 12  is a partial enlarged plan view showing a configuration of the rotor shown in  FIG. 11 . 
         FIG. 13  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 11 . 
         FIG. 14  is a partial enlarged plan view for describing a state after centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 11 . 
         FIG. 15  is a plan view showing a configuration of a rotor of embodiment 3 of the present invention. 
         FIG. 16  is a partial enlarged plan view showing a configuration of the rotor shown in  FIG. 15 . 
         FIG. 17  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 15 . 
         FIG. 18  is a partial enlarged plan view for describing a state where centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 15 . 
         FIG. 19  is a plan view showing a configuration of a rotor of embodiment 4 of the present invention. 
         FIG. 20  is a partial enlarged plan view showing a configuration of the rotor shown in  FIG. 19 . 
         FIG. 21  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 19 . 
         FIG. 22  is a partial enlarged plan view for describing a state after centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 19 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
     Hereinafter, embodiments of the invention of the present application will be described.  FIG. 1  is a plan view showing a configuration of a rotor according to embodiment 1 of the present invention.  FIG. 2  is a partial enlarged plan view showing a configuration of a ⅛ model of the rotor shown in  FIG. 1 .  FIG. 3  is a perspective view showing a configuration of a rotary electric machine using the rotor shown in  FIG. 1 .  FIG. 4  is a plan view showing a configuration of the rotary electric machine shown in  FIG. 3 .  FIG. 5  is a flow chart for describing a method for manufacturing the rotor shown in  FIG. 1 .  FIG. 6  to  FIG. 9  are partial enlarged plan views showing manufacturing steps for the rotor shown in  FIG. 1 . 
       FIG. 10  is a diagram showing the difference in torque between the rotor of the present invention and a rotor of a comparative example. It is noted that hatching for facilitating understanding of the structures is provided only in  FIG. 9 . In other drawings, the structures are the same as those shown in  FIG. 9 , and hatching is omitted. 
     In the present embodiment, an example of a rotary electric machine  1  of a permanent magnet type having 8 poles and 48 slots is described. However, the number of poles and the number of slots of the rotary electric machine  1  can be increased or decreased as appropriate, and such configurations are applicable not only to the present embodiment but also to embodiments thereafter. Thus, the description thereof is omitted as appropriate. 
     In  FIG. 3  and  FIG. 4 , the rotary electric machine  1  is composed of a stator  2 , a rotor  3 , and a shaft  4 . From the outer peripheral side of the rotary electric machine  1 , the stator  2 , the rotor  3 , and the shaft  4  are arranged in this order. The stator  2  is disposed with an air gap  5 , which is a gap, interposed between the stator  2  and the rotor  3 . The air gap  5  is formed such that an interval L 2  in the radial direction is 0.1 mm to 2.5 mm. 
     The stator  2  has a stator core  20  and a coil  21 . The stator core  20  is formed in an annular shape. The stator core  20  is formed, for example, by stacking a plurality of electromagnetic steel sheets in an axial direction Y. The thickness of one electromagnetic steel sheet is 0.1 mm to 1.0 mm in many cases. In the present embodiment, an example has been shown in which the stator core  20  is composed of electromagnetic steel sheets, but without being limited thereto, the stator core  20  may be composed of materials other than the electromagnetic steel sheet. Such configurations are also applicable to the embodiments below, and thus, the description thereof is omitted as appropriate. The coil  21  wound on the stator core  20  may be either of a distributed-winding type or a concentrated-winding type. 
     The rotor  3  is formed, with a rotor core  30  being fixed to the shaft  4  which is inserted at the axial position thereof. The rotor  3  is a permanent magnet type rotor in which the rotor core  30  is disposed inside the stator  2  and which is provided with permanent magnets  6 . The shaft  4  is fixed to the rotor core  30  through, for example, shrink fitting, press-fitting, or the like. 
     Next, details of the configuration of the rotor  3  are described with reference to  FIG. 1  and  FIG. 2 . As shown in  FIG. 1 , the rotor  3  is composed of : the rotor core  30  in which a plurality of insertion holes  7  each penetrating the rotor core  30  in the axial direction Y are formed with intervals thereamong in a circumferential direction Z; permanent magnets  6  (hereinafter, the permanent magnet is referred to as “magnet”) respectively provided in the insertion holes  7 ; and the shaft  4  for rotating the rotor core  30 . 
     Thus, each magnet  6  is formed in a shape and a size that allow the magnet  6  to be inserted in a corresponding insertion hole  7 . It is noted that, in the description below, the expression “magnet  6 ” is intended to refer to all the magnets  6  in the rotor  3 , and the expression “insertion hole  7 ” is intended to refer to all the insertion holes  7  in the rotor  3 . 
     As shown in  FIG. 2 , a plurality of the insertion holes  7  are formed with intervals interposed thereamong in the circumferential direction Z of the rotor core  30 , and are formed in a plurality of layers in a radial direction X. In the present embodiment, a case in which the insertion holes  7  are arranged in two layers in the radial direction X is described. The insertion hole  7  has two layers of a first insertion hole  71  and a second insertion hole  72 . In the second insertion hole  72 , a second bridge portion  42  is formed on the magnetic pole central axis, and a second insertion hole  72 A and a second insertion hole  72 B are formed by being divided in left-right line symmetry with respect to the central axis. 
     A first magnet  61  is inserted in the first insertion hole  71 , a second magnet  62 A is inserted in the second insertion hole  72 A, and a second magnet  62 B is inserted in the second insertion hole  72 B. Thus, each second magnet  62  is composed of the second magnet  62 A and the second magnet  62 B. 
     A hole-outside-peripheral-surface  80  and a hole-inside-peripheral-surface  81  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 , the hole-outside-peripheral-surface  80  being the lateral surface extending in the circumferential direction Z and at the outside in the radial direction X of each insertion hole  71 ,  72 , the hole-inside-peripheral-surface  81  being the lateral surface extending in the circumferential direction Z and at the inside in the radial direction X of each insertion hole  71 ,  72 . In addition, a magnet-outside-peripheral-surface  90  and a magnet-inside-peripheral-surface  91  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 , the magnet-outside-peripheral-surface  90  being the surface extending in the circumferential direction Z and at the outside in the radial direction X of each magnet  61 ,  62 , the magnet-inside-peripheral-surface  91  being the surface extending in the circumferential direction Z and at the inside in the radial direction X of each magnet  61 ,  62 . 
     When the radius of curvature for forming the hole-outside-peripheral-surface  80  of each insertion hole  71 ,  72  into an arc surface shape is defined as R1, and the radius of curvature for forming the magnet-outside-peripheral-surface  90  of each magnet  61 ,  62  into an arc surface shape is defined as R2, a relationship of R1&gt;R2 is satisfied. It is noted that the radius of curvature R1 and the radius of curvature R2 merely indicate the relationship therebetween, and the numerical values thereof are set as appropriate, respectively. 
     Since the insertion hole  7  and the magnet  6  are formed in this relationship, the hole-outside-peripheral-surface  80  of each insertion hole  71 ,  72  and the magnet-outside-peripheral-surface  90  of each magnet  61 ,  62  contact with each other at two locations of a first location E and a second location F. In addition, the hole-inside-peripheral-surface  81  of the first insertion hole  71  and the magnet-inside-peripheral-surface  91  of the first magnet  61  do not contact with each other and are provided with a gap therebetween, whereby a first gap portion  51  is formed. In addition, the hole-inside-peripheral-surface  81  of the second insertion hole  72  and the magnet-inside-peripheral-surface  91  of the second magnet  62  do not contact with each other and are provided with a gap therebetween, whereby a second gap portion  52  is formed. 
     As shown in  FIG. 9 , a first adhesive layer portion  11  is formed between the first location E and the second location F and between the hole-outside-peripheral-surface  80  of the first insertion hole  71  and the magnet-outside-peripheral-surface  90  of the first magnet  61 . In addition, a second adhesive layer portion  12  is formed between the hole-outside-peripheral-surface  80  of the second insertion hole  72  and the magnet-outside-peripheral-surface  90  of the second magnet  62 . A maximum interval L 1  in the radial direction X of each adhesive layer portion  11 ,  12  is about 5/100 (mm)&lt;L 1 &lt;20/100 (mm). 
     Each adhesive layer portion  11 ,  12  and the maximum interval L 1  are shown in  FIG. 9 , but indication thereof is omitted in other drawings as appropriate. Also in the embodiments below, indication of the adhesive layer portion  11 ,  12  and the maximum interval L 1  is omitted as appropriate. 
     When the maximum interval L 1  is smaller than 5/100 mm, the adhesive force of each adhesive layer portion  11 ,  12  is reduced, thereby causing unevenness on the surface of the adhesive agent. 
     When the maximum interval L 1  is greater than 20/100 mm, each magnet  61 ,  62  might slip off because the adhesive agent does not stay in the gap due to the surface tension of the adhesive agent during rotation. Therefore, the radius of curvature R1 and the radius of curvature R2 mentioned above are set such that the maximum interval L 1  satisfies the relationship described above. The maximum interval L 1  of each adhesive layer portion  11 ,  12  is set in accordance with the location corresponding thereto, within the range described above. 
     The above-described relationship between the radius of curvature R1 and the radius of curvature R2, and the above-described relationship of the maximum interval L 1  can be similarly realized at the insertion hole  7  and the magnet  6  in the each layer formed in the radial direction X, and thus, can also be realized similarly in the embodiments below. Therefore, description thereof is omitted as appropriate. 
     At the hole-inside-peripheral-surface  81  of the first insertion hole  71 , a first protruding portion  82  is formed which protrudes toward the outside in the radial direction X and which contacts with a circumferential-direction-side peripheral surface  92  in the circumferential direction Z of the first magnet  61 . The first magnet  61  inserted in the first insertion hole  71  moves in either of the directions in the circumferential direction Z, due to centrifugal force caused by rotation of the rotor core  30 . Therefore, the first protruding portion  82  is formed at two locations in the circumferential direction Z, so as to allow either of the two circumferential-direction-side peripheral surfaces  92  in the circumferential direction Z of the first magnet  61  to contact with the first protruding portion  82  in the circumferential direction Z within the first insertion hole  71 . The circumferential-direction-side peripheral surface  92  of the magnet  6  and the first protruding portion  82  that do not contact with each other has an interval therebetween, whereby the magnet  6  need not be pressed into the insertion hole  7  when the magnet  6  is to be inserted thereinto. This configuration also applies to the embodiments below. 
     At the hole-inside-peripheral-surface  81  of the second insertion hole  72 A,  72 B, a first protruding portion  82  is formed which protrudes toward the outside in the radial direction X and which contacts with the circumferential-direction-side peripheral surface  92  that is on the opposite side to the side where the second bridge portion  42  in the circumferential direction Z of the second magnet  62 A,  62 B is formed. The second magnet  62  inserted in the second insertion hole  72  moves to the outside in the radial direction X, due to centrifugal force caused by rotation of the rotor core  30 . Therefore, the first protruding portion  82  is formed on the opposite side to the second bridge portion  42 . Furthermore, the second magnet  62 A,  62 B does not contact with the second bridge portion  42 . A gap is provided between the second bridge portion  42  and another circumferential-direction-side peripheral surface  93 , which is the outer peripheral side of the circumferential-direction-side peripheral surface of the second magnet  62 A,  62 B, whereby a fourth gap portion  54  is formed. 
     Next, a method for manufacturing the rotor for a rotary electric machine configured as described above according to embodiment 1 is described with reference to  FIG. 5  to  FIG. 7 . First, an adhesive agent is applied to the magnet-outside-peripheral-surface  90  of the magnet  6  (step ST 1  in  FIG. 5 ). It is noted that, as the material of the adhesive agent, any material may be used as long as the material can fix the magnet  6  and the insertion hole  7  together. The adhesive agent that has been applied but has not been hardened is not shown. This also applies to the embodiments below. Next, as shown in  FIG. 6 , the magnet  6  is inserted into the insertion hole  7  (step ST 2  in  FIG. 5 ). At the insertion of the magnet  6 , the magnet  6  is inserted in the insertion hole  7  at a position that is as close as possible to the magnetic pole central axis of the rotor  3 . 
     Next, each magnet  6  is moved in the direction of an arrow K from the state shown in  FIG. 6 , and then, as shown in  FIG. 7 , the magnet-outside-peripheral-surface  90  of the magnet  6  is pressed against the hole-outside-peripheral-surface  80  of the insertion hole  7  (step ST 3  in  FIG. 5 ). For this pressing step, any condition may be employed as long as the condition does not cause cracking or chipping of the magnet  6  or the insertion hole  7 , wherein any means and any number of times of pressing the magnet  6  against the insertion hole  7  may be employed. 
     At this time, the magnet-inside-peripheral-surface  91  of the magnet  6  and the hole-inside-peripheral-surface  81  of the insertion hole  7  do not contact with each other, and a gap is provided between the magnet-inside-peripheral-surface  91  of the magnet  6  and the hole-inside-peripheral-surface  81  of the insertion hole  7 . Accordingly, the first gap portion  51  and the second gap portion  52  are each formed. 
     Next, the magnet  6  is moved in the direction of an arrow J shown in  FIG. 7 , that is, toward the first protruding portion  82 . It is noted that the first magnet  61  may be moved in either of the directions in the circumferential direction Z. Then, the circumferential-direction-side peripheral surface  92  of the magnet  6  is caused to contact with the first protruding portion  82  (step ST 4  in  FIG. 5 ). At this time, the second magnet  62 A,  62 B and the second bridge portion  42  do not contact with each other, and a gap is provided between the another circumferential-direction-side peripheral surface  93  of the second magnet  62 A,  62 B and the second bridge portion  42 , whereby the fourth gap portion  54  is formed. Next, the rotor core  30  is rotated, and the adhesive agent is hardened to form each adhesive layer portion  11 ,  12  (step ST 5  in  FIG. 5 ). 
     The rotor  3  is manufactured as described above, but before centrifugal force is caused to act by rotating the rotor core  30  and before the adhesive agent is hardened, the position of the magnet  6  could become unstable in the circumferential direction Z. Therefore, by rotating the rotor core  30  to cause centrifugal force to act, it is possible to make the position of the magnet  6  stable in the insertion hole  7  as shown in  FIG. 9 . In the following, this state is described. 
     First, before the centrifugal force acts, the magnet  6  and the insertion hole  7  are not completely fixed together by the adhesive agent, as shown in  FIG. 8 . Thus, after the first magnet  61  is inserted in the first insertion hole  71 , the first magnet  61  is pressed toward the outside in the radial direction X until the magnet-outside-peripheral-surface  90  contacts with the hole-outside-peripheral-surface  80 , whereby the magnet-outside-peripheral-surface  90  and the hole-outside-peripheral-surface  80  contact with each other at two points. However, since the first magnet  61  is not yet fixed in the circumferential direction Z of the rotor  3 , variation in the insertion manner of the first magnet  61  causes the first magnet  61  to contact with either of the left and right first protruding portions  82 , or to contact with neither of the left and right first protruding portions  82 . Thus, the position in the circumferential direction Z of the first magnet  61  is unstable. 
     Also with respect to the second magnet  62 , similarly to the first magnet  61 , after the second magnet  62  is inserted in the second insertion hole  72 , the second magnet  62  is pressed toward the outside in the radial direction X until the magnet-outside-peripheral-surface  90  contacts with the hole-outside-peripheral-surface  80 , whereby the magnet-outside-peripheral-surface  90  and the hole-outside-peripheral-surface  80  contact with each other at two points. Further, the circumferential-direction-side peripheral surface  92  of the second magnet  62  is caused to contact with the first protruding portion  82 . However, before the adhesive agent is hardened, the second magnet  62  is not yet fixed in the circumferential direction Z of the rotor  3 , and thus, the second magnet  62  could move to the magnetic pole central axis, that is, to the side where the second bridge portion  42  is formed. Thus, the position in the circumferential direction Z of the second magnet  62  is unstable. 
     In this state, the rotor core  30  is rotated to apply centrifugal force to the outside in the radial direction X of the rotor core  30 , and the adhesive agent is hardened to form each adhesive layer portion  11 ,  12  ( FIG. 9 ). That is, when the rotor  3  is rotated, centrifugal force toward the outside in the radial direction X of the rotor  3  is applied to the magnet  6  and the insertion hole  7 . Due to this centrifugal force, the first magnet  61  moves to the outside in the radial direction X of the rotor  3 , and the contacts at the two points between the magnet-outside-peripheral-surface  90  of the first magnet  61  and the hole-outside-peripheral-surface  80  of the first insertion hole  71  are fixed at the first location E and the second location F. In addition, either of the left and right circumferential-direction-side peripheral surfaces  92  in the circumferential direction Z of the first magnet  61  contacts with a corresponding one of the left and right first protruding portions  82 . As a result, the first magnet  61  contacts with the first insertion hole  71  at three locations therein, thereby being stabilized at a specific position. 
     Similarly to the first magnet  61 , also to the second magnet  62 A,  62 B, centrifugal force toward the outside in the radial direction X of the rotor  3  is applied. Due to this centrifugal force, the second magnet  62 A,  62 B moves to the outside in the radial direction X of the rotor  3 , and the contacts at the two points between the magnet-outside-peripheral-surface  90  of the second magnet  62 A,  62 B and the hole-outside-peripheral-surface  80  of the second insertion hole  72 A,  72 B are fixed at the first location E and the second location F. In addition, the circumferential-direction-side peripheral surface  92  of the second magnet  62 A,  62 B contacts with the first protruding portion  82 . As a result, the second magnet  62  contacts with the second insertion hole  72  at three locations therein, thereby being stabilized at a specific position. 
     The above-described relationship between the magnet  6  and the insertion hole  7  in the fixation thereof before centrifugal force is caused to act on the rotor core  30  and after centrifugal force is caused to act on the rotor core  30  is the same also in the embodiments below, and thus, description thereof is omitted as appropriate. 
     Next, a method for assembling the rotary electric machine  1  by use of the rotor  3  manufactured as described above is described. With respect to the stator  2 , the stator core  20  is formed by stamping an electromagnetic steel sheet which is a main material. The method for forming the stator core  20  is not limited to stamping an electromagnetic steel sheet. Next, an insulating sheet is attached to the coil  21  assembled in an annular shape, and the resultant coil  21  is inserted in the stator core  20 . It is noted that the method for assembling the coil  21  and the stator core  20  is not limited to this method. Next, the shaft  4  is fixed to the rotor core  30  of the rotor  3  manufactured as described above. Next, the rotor  3  is inserted in the stator  2  with the air gap  5  therebetween, to assemble the rotor  3  and the stator  2  together, whereby the rotary electric machine  1  is manufactured. It is noted that the configuration of the rotary electric machine  1  can be realized similarly in the embodiments below, and thus, is not described and not shown in the drawings. 
     According to embodiment 1 configured as described above, since a gap is provided so as to prevent eventual contact between the hole-inside-peripheral-surface of the insertion hole and the magnet-inside-peripheral-surface of the magnet, the magnet can be easily inserted in the insertion hole. Then, eventually, the magnet-outside-peripheral-surface of the magnet and the hole-outside-peripheral-surface of the insertion hole are caused to contact with each other at two locations, and the magnet and the first protruding portion are caused to contact with each other, whereby the magnet and the insertion hole contact with each other at three locations. Accordingly, the positional accuracy of the magnet in the insertion hole can be enhanced. Thus, decrease in torque, increase in stress applied to the rotor core, and increase in rotation imbalance due to variation in the position of the magnet can be reduced. 
     Specifically,  FIG. 10  shows the difference between torque in a comparative example employing a rotary electric machine where magnets are inserted and fixed in insertion holes through pressure welding, and torque in the present invention. Both torques were calculated under the same condition. Apparent from  FIG. 10 , the torque in the present invention is greater. From this, it has been confirmed that the present invention can prevent variation of decrease in the torque of the magnets. 
     In addition, the magnet-outside-peripheral-surface of the magnet and the hole-outside-peripheral-surface of the insertion hole are each formed in an arc surface shape that inwardly protrudes in the radial direction. This reliably causes the magnet-outside-peripheral-surface of the magnet and the hole-outside-peripheral-surface of the insertion hole to contact with each other at two locations. Accordingly, the positional accuracy of the magnet in the insertion hole can be further enhanced. 
     In addition, since the bridge portion in the left-right line symmetry is formed on the magnetic pole central axis in the insertion hole, concentration of stress applied to the rotor core can be reduced. 
     In addition, with the rotor core being rotated, the adhesive agent is hardened to form the adhesive layer portion, and thus, the positional accuracy of the magnet in the insertion hole can be further enhanced. 
     In the present embodiment, an example has been described in which: the magnet is pressed against the first protruding portion; and then, with the rotor core being rotated, the adhesive agent is hardened to form the adhesive layer portion. However, the present invention is not limited thereto. For example, a configuration may be employed in which: with the rotor core being rotated, the magnet is pressed against the first protruding portion and the adhesive agent is hardened to form the adhesive layer portion. In this case, since the magnet is pressed against the first protruding portion with the rotor core being rotated, the number of steps can be reduced, and thus, low cost manufacture can be realized. 
     In the present embodiment, an example has been described in which: the hole-outside-peripheral-surface  80  of each insertion hole  71 ,  72  and the magnet-outside-peripheral-surface  90  of each magnet  61 ,  62  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 ; and the hole-outside-peripheral-surface  80  and the magnet-outside-peripheral-surface  90  are caused to contact with each other at the two locations of the first location E and the second location F. However, the present invention is not limited thereto. Even when another shape is employed, if the hole-outside-peripheral-surface  80  of the insertion hole  7  and the magnet-outside-peripheral-surface  90  of the magnet  6  are caused to contact with each other at the two locations of the first location E and the second location F, and if each adhesive layer portion  11 ,  12  can be formed between the first location E and the second location F and between the hole-outside-peripheral-surface  80  of the insertion hole  7  and the magnet-outside-peripheral-surface  90  of the magnet  6 , similar configurations to those of the present embodiment can be realized, and the same effects as those in the present embodiment can be realized. This also applies to the embodiments below, and thus, description thereof is omitted as appropriate. 
     Embodiment 2 
       FIG. 11  is a plan view showing a configuration of a rotor of embodiment 2 of the present invention.  FIG. 12  is a partial enlarged plan view showing a configuration of a ⅛ model of the rotor shown in  FIG. 11 .  FIG. 13  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 11 .  FIG. 14  is a partial enlarged plan view for describing a state after centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 11 . It is noted that hatching for facilitating understanding of the structures is provided only in  FIG. 14 . In other drawings, the structures are the same as those shown in  FIG. 14 , and hatching is omitted. 
     In the drawings, parts similar to those in embodiment 1 above are denoted by the same reference characters and description thereof is omitted. At the second bridge portion  42  in the second insertion hole  72 , second protruding portions  83  are formed which respectively protrude to the second magnet  62  sides in the second insertion hole  72 , and which do not contact with the second magnets  62 , respectively. 
     The rotor for the rotary electric machine of embodiment 2 configured as described above can be manufactured as shown in  FIG. 5  as in embodiment 1 above. However, before centrifugal force is caused to act by rotating the rotor core  30  and before the adhesive agent is hardened, the position of the magnet  6  could become unstable in the circumferential direction Z. Thus, by rotating the rotor core  30  to cause centrifugal force to act, it is possible to make the position of the magnet  6  stable in the insertion hole  7  as shown in  FIG. 14 . In the following, this state is described. 
     First, before centrifugal force acts, the magnet  6  and the insertion hole  7  are not completely fixed together by the adhesive agent as shown in  FIG. 13 . The relationship between the first magnet  61  and the first insertion hole  71  is the same as in embodiment 1 above, and description thereof is omitted. After the second magnet  62  is inserted in the second insertion hole  72 , the second magnet  62  is pressed toward the outside in the radial direction X until the magnet-outside-peripheral-surface  90  contacts with the hole-outside-peripheral-surface  80 , whereby the magnet-outside-peripheral-surface  90  and the hole-outside-peripheral-surface  80  contact with each other at two points. Further, the circumferential-direction-side peripheral surface  92  of the second magnet  62  is caused to contact with the first protruding portion  82 . However, before the adhesive agent is hardened, the second magnet  62  is not yet fixed in the circumferential direction Z of the rotor  3 , and thus, the second magnet  62  could move to the magnetic pole central axis, that is, to the side where the second bridge portion  42  is formed. As a result, the another circumferential-direction-side peripheral surface  93  of the second magnet  62  contacts with the second protruding portion  83  formed at the second bridge portion  42 . This hinders the second magnet  62  from being disposed at a specific position in the circumferential direction Z. 
     In this state, the rotor core  30  is rotated to apply centrifugal force to the outside in the radial direction X of the rotor core  30 . Then, the adhesive agent is hardened to form each adhesive layer portion  11 ,  12  ( FIG. 14 ). That is, when the rotor  3  is rotated, centrifugal force toward the outside in the radial direction X of the rotor  3  is applied to the magnet  6 , i.e., to the second magnet  62 A,  62 B. 
     Then, the second magnet  62 A,  62 B moves to the outside in the radial direction X of the rotor  3 , and the contacts at the two points between the magnet-outside-peripheral-surface  90  of the second magnet  62 A,  62 B and the hole-outside-peripheral-surface  80  of the second insertion hole  72 A,  82 B are fixed at the first location E and the second location F. In addition, the circumferential-direction-side peripheral surface  92  of the second magnet  62 A,  62 B contacts with the first protruding portion  82 . As a result, the second magnet  62  contacts with the second insertion hole  72  at three locations therein, thereby being stabilized at a specific position. 
     According to embodiment 2 configured as described above, it is needless to say that the same effects as those in embodiment 1 above can be exhibited. If the insertion hole having the bridge portion formed therein is not provided with the second protruding portions, the magnets and the bridge portion might contact with each other, and in such a case, the distance of flux barrier that hinders magnetic flux from passing therethrough is shortened. Thus, magnetic flux leakage of the magnets could occur. 
     In the present embodiment 2, since the insertion hole having the bridge portion formed therein is provided with the second protruding portions, the magnets and the second protruding portions contact with each other, and the magnets and the bridge portion do not contact with each other, whereby the flux barrier can be secured between the magnets and the bridge portion. Thus, magnetic flux leakage of the magnets can be suppressed, and decrease in torque can be prevented. 
     Embodiment 3 
       FIG. 15  is a plan view showing a configuration of a rotor of embodiment 3 of the present invention.  FIG. 16  is a partial enlarged plan view showing a configuration of a ⅛ model of the rotor shown in  FIG. 15 .  FIG. 17  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 15 .  FIG. 18  is a partial enlarged plan view for describing a state after centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 15 . It is noted that hatching for facilitating understanding of the structures is provided only in  FIG. 18 . In other drawings, the structures are the same as those shown in  FIG. 18 , and hatching is omitted. 
     In the drawings, parts similar to those in the above embodiments are denoted by the same reference characters and description thereof is omitted. The first insertion hole  71  is divided by a first bridge portion  41 , and thus, is composed of a first insertion hole  71 A and a first insertion hole  71 B. In the first insertion hole  71 A and the first insertion hole  71 B, a first magnet  61 A and a first magnet  61 B are disposed, respectively. Thus, the first magnet  61  is composed of the first magnet  61 A and the first magnet  61 B. The first bridge portion  41  is formed so that the first insertion hole  71 A and the first insertion hole  71 B are in left-right line symmetry with respect to the magnetic pole central axis in the first insertion hole  71 . Accordingly, concentration of stress applied to the rotor core is reduced. 
     Similarly to the embodiments above, the hole-outside-peripheral-surface  80  and the hole-inside-peripheral-surface  81  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 , the hole-outside-peripheral-surface  80  being the lateral surface extending in the circumferential direction Z and at the outside in the radial direction X of the first insertion hole  71 A,  71 B, the hole-inside-peripheral-surface  81  being the lateral surface extending in the circumferential direction Z and at the inside in the radial direction X of the first insertion hole  71 A,  71 B. In addition, similarly to the embodiments above, the magnet-outside-peripheral-surface  90  and the magnet-inside-peripheral-surface  91  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 , the magnet-outside-peripheral-surface  90  being the surface extending in the circumferential direction Z and at the outside in the radial direction X of the first magnet  61 A,  61 B, the magnet-inside-peripheral-surface  91  being the surface extending in the circumferential direction Z and at the inside in the radial direction X of the first magnet  61 A,  61 B. The first gap portion  51  and the first adhesive layer portion  11  are formed in the same manner as in the embodiments above. 
     At the hole-inside-peripheral-surface  81  of the first insertion hole  71 A,  71 B, the first protruding portion  82  is formed which protrudes toward the outside in the radial direction X and which contacts with the circumferential-direction-side peripheral surface  92  that is on the opposite side to the side where the first bridge portion  41  in the circumferential direction Z of the first magnet  61 A,  61 B is formed. The first magnet  61  inserted in the first insertion hole  71  moves to the outside in the radial direction X, due to centrifugal force caused by rotation of the rotor core  30 . Furthermore, the first magnet  61 A,  61 B does not contact with the first bridge portion  41 . A gap is provided between the first bridge portion  41  and the another circumferential-direction-side peripheral surface  93  of the first magnet  61 A,  61 B, whereby the fourth gap portion  54  is formed. 
     The rotor for the rotary electric machine of embodiment 3 configured as described above can be manufactured as shown in  FIG. 5  as in the embodiments above. However, before centrifugal force is caused to act by rotating the rotor core  30  and before the adhesive agent is hardened, the position of the magnet  6  could become unstable in the circumferential direction Z. Thus, by rotating the rotor core  30  to cause centrifugal force to act, it is possible to make the position of the magnet  6  stable in the insertion hole  7  as shown in  FIG. 18 . In the following, this state is described. 
     First, before centrifugal force acts, the magnet  6  and the insertion hole  7  are not completely fixed together by the adhesive agent as shown in  FIG. 17 . Thus, after the first magnet  61  is inserted in the first insertion hole  71 , the first magnet  61  is pressed toward the outside in the radial direction X until the magnet-outside-peripheral-surface  90  contacts with the hole-outside-peripheral-surface  80 , whereby the magnet-outside-peripheral-surface  90  and the hole-outside-peripheral-surface  80  contact with each other at two points. Further, the circumferential-direction-side peripheral surface  92  of the second magnet  62  is caused to contact with first protruding portion  82 . However, before the adhesive agent is hardened, the first magnet  61  is not yet fixed in the circumferential direction Z of the rotor  3 , and thus, the first magnet  61  could move to the magnetic pole central axis, that is, to the side where the first bridge portion  41  is formed. Thus, the position in the circumferential direction Z of the first magnet  61  is unstable. It is noted that the relationship between the second magnet  62  and the second insertion hole  72  is the same as that in embodiment 1 above, and description thereof is omitted. 
     In this state, the rotor core  30  is rotated to apply centrifugal force to the outside in the radial direction X of the rotor core  30 , and the adhesive agent is hardened to form each adhesive layer portion  11 ,  12  ( FIG. 18 ). That is, when the rotor  3  is rotated, centrifugal force toward the outside in the radial direction X of the rotor  3  is applied to the magnet  6  and the insertion hole  7 . Due to this centrifugal force, the first magnet  61  moves to the outside in the radial direction X of the rotor  3 , and the contacts at the two points between the magnet-outside-peripheral-surface  90  of the first magnet  61  and the hole-outside-peripheral-surface  80  of the first insertion hole  71  are fixed at the first location E and the second location F. In addition, the circumferential-direction-side peripheral surface  92  of the first magnet  61  contacts with the first protruding portion  82 . As a result, the first magnet  61  contacts with the first insertion hole  71  at three locations therein, thereby being stabilized at a specific position. 
     According to embodiment 3 configured as described above, it is needless to say that the same effects as those in the embodiments above can be exhibited. Furthermore, even in a case where the first bridge portion is formed in the first insertion hole, when the rotor is rotated to apply centrifugal force to the first magnet, the magnet-outside-peripheral-surface of the first magnet and the hole-outside-peripheral-surface of the first insertion hole contact with each other at two locations, and the circumferential-direction-side peripheral surface of the first magnet contacts with the first protruding portion. Thus, the positional accuracy of the first magnet can be enhanced. 
     Embodiment 4 
       FIG. 19  is a plan view showing a configuration of a rotor of embodiment 4 of the present invention.  FIG. 20  is a partial enlarged plan view showing a configuration of a ⅛ model of the rotor shown in  FIG. 19 .  FIG. 21  is a partial enlarged plan view for describing a state before centrifugal force is caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 19 .  FIG. 22  is a partial enlarged plan view for describing a state where centrifugal force has been caused to act on the rotor core in a manufacturing step for the rotor shown in  FIG. 19 . It is noted that hatching for facilitating understanding of the structures is provided only in  FIG. 22 . In other drawings, the structures are the same as those shown in  FIG. 22 , and hatching is omitted. 
     In the drawings, parts similar to those in the above embodiments are denoted by the same reference characters and description thereof is omitted. In the present embodiment 4, an example is shown in which the insertion hole  7  is formed in three layers in the radial direction X of the rotor  3 , whereby a third insertion hole  73  is provided. Thus, a third magnet  63  is inserted in the third insertion hole  73 . In addition, the hole-outside-peripheral-surface  80  and the hole-inside-peripheral-surface  81  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 , the hole-outside-peripheral-surface  80  being the lateral surface extending in the circumferential direction Z and at the outside in the radial direction X of the third insertion hole  73 , the hole-inside-peripheral-surface  81  being the lateral surface extending in the circumferential direction Z and at the inside in the radial direction X of the third insertion hole  73 . In addition, the magnet-outside-peripheral-surface  90  and the magnet-inside-peripheral-surface  91  are each formed in an arc surface shape that inwardly protrudes in the radial direction X of the rotor  3 , the magnet-outside-peripheral-surface  90  being the surface extending in the circumferential direction Z and at the outside in the radial direction X of the third magnet  63 , the magnet-inside-peripheral-surface  91  being the surface extending in the circumferential direction Z and at the inside in the radial direction X of the third magnet  63 . 
     Furthermore, as shown in  FIG. 22 , the hole-outside-peripheral-surface  80  of the third insertion hole  73  and the magnet-outside-peripheral-surface  90  of the third magnet  63  contact with each other at two locations of the first location E and the second location F. The hole-inside-peripheral-surface  81  of the third insertion hole  73  and the magnet-inside-peripheral-surface  91  of the third magnet  63  do not contact with each other, with a gap provided therebetween, whereby a third gap portion  53  is formed. 
     A third adhesive layer portion  13  is formed between the first location E and the second location F and between the hole-outside-peripheral-surface  80  of the third insertion hole  73  and the magnet-outside-peripheral-surface  90  of the third magnet  63 . The maximum interval L 1  in the radial direction X of the third adhesive layer portion  13  is set in the same manner as in the embodiments above. At the hole-inside-peripheral-surface  81  of the third insertion hole  73 , the first protruding portion  82  which protrudes toward the outside in the radial direction X and which contacts with the circumferential-direction-side peripheral surface  92  in the circumferential direction Z of the third magnet  63  is formed in the circumferential direction Z. It is unknown which of the directions in the circumferential direction Z the third magnet  63  inserted in the third insertion hole  73  moves in due to the centrifugal force caused by rotation of the rotor core  30 . Therefore, the first protruding portion  82  is formed at two locations in the circumferential direction Z, so as to allow either of the circumferential-direction-side peripheral surfaces  92  in the circumferential direction Z of the third magnet  63  to contact with the first protruding portion  82  in the circumferential direction Z within the third insertion hole  73 . 
     Similarly to the embodiments above, the rotor for the rotary electric machine of embodiment 4 configured as described above can be manufactured as shown in  FIG. 5 . However, before centrifugal force is caused to act by rotating the rotor core  30 , and before the adhesive agent is hardened, the position of the magnet  6  could become unstable in the circumferential direction Z. Thus, by rotating the rotor core  30  to cause centrifugal force to act, it is possible to make the position of the magnet  6  stable in the insertion hole  7  as shown in  FIG. 22 . In the following, this state is described. 
     First, before centrifugal force acts, the magnet  6  and the insertion hole  7  are not completely fixed together by the adhesive agent as shown in  FIG. 21 . It is noted that the relationship between the first magnet  61  and the first insertion hole  71 , and the relationship between the second magnet  62  and the second insertion hole  72  are the same as those in embodiment 1 above, and thus, the description thereof is omitted. After the third magnet  63  is inserted in the third insertion hole  73 , the third magnet  63  is pressed toward the outside in the radial direction X until the magnet-outside-peripheral-surface  90  contacts with the hole-outside-peripheral-surface  80 , whereby the magnet-outside-peripheral-surface  90  and the hole-outside-peripheral-surface  80  contact with each other at two points. Further, the circumferential-direction-side peripheral surface  92  of the second magnet  62  is caused to contact with the first protruding portion  82 . However, before the adhesive agent is hardened, the third magnet  63  is not yet fixed in the circumferential direction Z of the rotor  3 . Thus, variation in the insertion manner of the third magnet  63  causes the third magnet  63  to contact with either of the left and right first protruding portions  82 , or to contact with neither of the left and right first protruding portions  82 . Thus, the position in the circumferential direction Z of the third magnet  63  is unstable. 
     In this state, the rotor core  30  is rotated to apply centrifugal force to the outside in the radial direction X of the rotor core  30 , and the adhesive agent is hardened to form each adhesive layer portion  11 ,  12 ,  13  (see  FIG. 22 ). That is, when the rotor  3  is rotated, centrifugal force toward the outside in the radial direction X of the rotor  3  is applied to the magnet  6  and insertion hole  7 . Due to this centrifugal force, the third magnet  63  moves to the outside in the radial direction X of the rotor  3 , and the contacts at two points between the magnet-outside-peripheral-surface  90  of the third magnet  63  and the hole-outside-peripheral-surface  80  of the third insertion hole  73  are fixed at the first location E and the second location F. In addition, either of the left and right circumferential-direction-side peripheral surfaces  92  in the circumferential direction Z of the third magnet  63  contacts with a corresponding one of the left and right first protruding portions  82 . As a result, the third magnet  63  contacts with the third insertion hole  73  at three locations therein, thereby being stabilized at a specific position. 
     According to embodiment 4 configured as described above, it is needless to say that the same effects as those in the embodiments above can be exhibited. Furthermore, by setting the number of layers of the insertion hole to three, the amount of magnetic flux flowing in the rotor can be increased, and thus, torque can be enhanced. 
     It is noted that, within the scope of the present invention, the above embodiments may be combined with each other, or each of the above embodiments may be modified or simplified as appropriate.