Patent Publication Number: US-2019186495-A1

Title: Blower

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a blower. 
     2. Description of the Related Art 
     A blower in which an impeller is mounted on a rotor cup that holds a rotor magnet is known. For example, as a conventional blower, a blower that includes a motor yoke, serving as a rotor cup, and an impeller is known. 
     In blowers, such as the conventional blower, when the rotor cup and the impeller are rotated at a high speed, an impeller cup of the impeller mounted on the rotor cup may become deformed in a radial direction by, for example, a centrifugal force. Therefore, the flow of air around the impeller cup changes and air quantity characteristics of the blower may deteriorate. In addition, a blade portion of the impeller may become damaged due to the blade portion coming into contact with a housing that surrounds the impeller. 
     SUMMARY OF THE INVENTION 
     A blower of an exemplary embodiment of the present disclosure includes a motor that includes a shaft that is disposed along a central axis extending in an up-down direction, and an impeller that is rotated around the central axis by the motor, wherein the motor includes a stator that surrounds the shaft on an outer side of the shaft in a radial direction, a rotor magnet that faces the stator in the radial direction with a gap interposed therebetween on an outer side of the stator in the radial direction, and a rotor cup that includes a first cylindrical portion that has a cylindrical shape and that holds the rotor magnet, the impeller includes an impeller cup including a cylindrical second cylindrical portion that surrounds the first cylindrical portion on an outer side of the rotor cup in the radial direction, and a plurality of blade portions that are located on a radial-direction outer surface of the second cylindrical portion, the rotor cup includes a flange portion that protrudes outward in the radial direction from a lower portion of the first cylindrical portion, one of the flange portion and the impeller cup includes a first hole portion that is recessed in an axial direction and the other of the flange portion and the impeller cup includes a first protruding portion, and at least a portion of the first protruding portion is located inside the first hole portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view showing a blower of a first exemplary embodiment of the present disclosure. 
         FIG. 2  is a perspective view showing an impeller and a rotor cup of the first exemplary embodiment of the present disclosure. 
         FIG. 3  is a top view of the rotor cup of the first exemplary embodiment of the present disclosure. 
         FIG. 4  is a sectional view showing a portion of the impeller and a portion of the rotor cup of the first exemplary embodiment of the present disclosure. 
         FIG. 5  is a perspective view showing a portion of the impeller and a portion of the rotor cup of the first exemplary embodiment of the present disclosure. 
         FIG. 6  is a perspective view showing a portion of the impeller of the first exemplary embodiment of the present disclosure. 
         FIG. 7  is a perspective view showing an impeller and a rotor cup of a second exemplary embodiment of the present disclosure. 
         FIG. 8  is a perspective view showing the rotor cup of the second exemplary embodiment of the present disclosure. 
         FIG. 9  is a top view of the rotor cup of the second exemplary embodiment of the present disclosure. 
         FIG. 10  is a sectional view showing a portion of the impeller and a portion of the rotor cup of the second exemplary embodiment of the present disclosure. 
         FIG. 11  is a perspective view showing the impeller of the second exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A Z-axis direction that is shown as appropriate in each figure is an up-down direction in which a positive side is an upper side and a negative side is a lower side. Note that the up-down direction, the upper side, and the lower side are names for merely describing the relationships between relative positions of each portion. The actual arrangement relationships or the like may be, for example, arrangement relationships other than, for example, the arrangement relationships indicated by these names. 
     As shown in  FIG. 1 , a blower  10  of the embodiment includes a motor supporting section  40 , a motor  30  including a shaft  31  that is disposed along a central axis J extending in the up-down direction, an impeller  20 , a circuit board  80 , and a housing  50 . In the description below, a direction parallel to the central axis J, that is, the up-down direction is simply called “axial direction Z”. A radial direction around the central axis J is simply called “radial direction”, and a peripheral direction around the central axis J is simply called “peripheral direction”. 
     The motor supporting section  40  supports the motor  30 . The motor supporting section  40  includes a bottom plate portion  42  and a stator supporting portion  41 . The bottom plate portion  42  has the shape of a ring plate having the central axis J as the center. The stator supporting portion  41  has a cylindrical shape extending upward from an inner edge portion of the bottom plate portion  42  in the radial direction. The stator supporting portion  41  opens on both sides in the axial direction Z. Two bearings disposed apart from each other in the axial direction Z with a gap interposed therebetween are fixed to an inner surface of the stator supporting portion  41  in the radial direction. 
     The motor  30  includes the shaft  31 , a stator  34 , a rotor cup  32 , and a rotor magnet  33 . The shaft  31  is rotatably supported by the two bearings that are fixed to the inner surface of the stator supporting portion  41  in the radial direction. An upper end portion of the shaft  31  protrudes to a location above the stator supporting portion  41 . A cylindrical mounting member  36  is fitted and fixed to the upper end portion of the shaft  31 . 
     On an outer side of the shaft  31  in the radial direction, the stator  34  surrounds the shaft  31 . The stator  34  has, for example, a ring shape having the central axis J as the center. The stator  34  is fixed to an outer surface of the stator supporting portion  41  in the radial direction. 
     The rotor cup  32  has a cylindrical shape that opens on the lower side. The rotor cup  32  is made of, for example, a metal. The rotor cup  32  includes a first cylindrical portion  32   b , a cover portion  32   a , and flange portions  32   c . The first cylindrical portion  32   b  has a cylindrical shape extending in the axial direction Z and having the central axis J as the center. On an outer side of the stator  34  in the radial direction, the first cylindrical portion  32   b  surrounds the stator  34 . 
     The cover portion  32   a  has the shape of a ring plate having the central axis J as the center. An outer edge portion of the cover portion  32   a  in the radial direction is connected to an upper end portion of the first cylindrical portion  32   b . That is, the cover portion  32   a  is located on the upper end portion of the first cylindrical portion  32   b . The cover portion  32   a  covers the upper side of the stator  34 . An inner edge portion  32   f  of the cover portion  32   a  in the radial direction is fixed to the upper end portion of the shaft  31  with the mounting member  36  interposed therebetween. Accordingly, the rotor cup  32  is fixed to the shaft  31 . The outer edge portion of the cover portion  32   a  in the radial direction is an impeller supporting portion  32   h  that is recessed downward. As shown in  FIGS. 2 and 3 , the cover portion  32   a  has a plurality of through holes  32   g  that extend through the cover portion  32   a  in the axial direction Z. 
     Each flange portion  32   c  protrudes outward in the radial direction from a lower portion of the first cylindrical portion  32   b . More specifically, each flange portion  32   c  protrudes outward in the radial direction from a lower end portion of the first cylindrical portion  32   b . In the embodiment, the rotor cup  32  includes the plurality of flange portions  32   c . In  FIGS. 2 and 3 , the number of flange portions  32   c  is, for example, 5. The plurality of flange portions  32   c  are disposed at equal intervals around a circumference in the peripheral direction. 
     As shown in  FIG. 3 , the shape of each flange portion  32   c  as viewed from the upper side of each flange portion  32   c  is a substantially trapezoidal shape having a dimension in the peripheral direction that decreases from its inner side in the radial direction towards its outer side in the radial direction. Two edge portions  32   d  on respective peripheral-direction sides of each flange portion  32   c  are each inclined in a direction so as to approach the edge portion  32   d  on the opposite side from the inner side in the radial direction towards the outer side in the radial direction. Therefore, for example, when a part of a ring plate portion that protrudes outward in the radial direction from the first cylindrical portion  32   b  is punched out by using a press die to manufacture the flange portions  32   c , the angle of a region along an outer surface of the first cylindrical portion  32   b  in the radial direction and each edge portion  32   d  at the punched-out portion is an obtuse angle. This allows the angle of the press die used to punch out a part of the ring plate portion to be an obtuse angle. Therefore, it is possible to suppress wear of the press die and to increase the life of the press die. 
     As shown in  FIG. 4 , in the radial direction, an outer end portion of a flange portion  32   c  in the radial direction is located substantially in correspondence with the position of a radial-direction outer surface of a second cylindrical portion  21   a  (described later) of an impeller cup  21 . In the radial direction, the outer end portion of the flange portion  32   c  in the radial direction is located slightly inward of the radial-direction outer surface of the second cylindrical portion  21   a . Therefore, compared to when the flange portion protrudes outward of the second cylindrical portion in the radial direction, the flow of air that flows along the radial-direction outer surface of the second cylindrical portion  21   a  is less likely to be hindered. Consequently, it is possible to suppress a reduction in the air quantity of the blower  10  and to reduce noise that is produced from the blower  10 . 
     Each flange portion  32   c  includes a first hole portion  35  that is recessed in the axial direction Z. In the embodiment, each first hole portion  35  extends through its corresponding flange portion  32   c  in the axial direction Z. As shown in  FIG. 3 , each first hole portion  35  extends in the peripheral direction. Each first hole portion  35  is located in the center of its corresponding flange portion  32   c  in the radial direction. Therefore, a radial-direction dimension L 1  of a radial-direction inner portion of the first hole portion  35  of each flange portion  32   c  is substantially the same as a radial-direction dimension L 2  of a radial-direction outer portion of the first hole portion  35  of each flange portion  32   c . This makes it easier to ensure the strength of each flange portion  32   c . In addition, when forming each first hole portion  35  by punching out a part of its corresponding flange portion  32   c , each first hole portion  35  is easier to form. 
     In the embodiment, each first hole portion  35  is formed, for example, by punching out a part of its corresponding flange portion  32   c  by using a press die. More specifically, with a lower surface of each flange portion  32   c  being set in the die, a punch is brought close to each flange portion  32   c  from the upper side of each flange portion  32   c  to punch out a part of each flange portion  32   c . Therefore, as shown in  FIG. 5 , for example, a burr  32   e  is formed in a peripheral edge portion of a first hole portion  35  at the lower surface of its corresponding flange portion  32   c . That is, the rotor cup  32  includes the burrs  32   e  that are each located on the peripheral edge portion of its corresponding first hole portion  35  at the lower surface of its corresponding flange portion  32   c.    
     As shown in  FIG. 1 , the rotor magnet  33  is fixed to an inner surface of the first cylindrical portion  32   b  in the radial direction. Therefore, the first cylindrical portion  32   b  holds the rotor magnet  33 . On the outer side of the stator  34  in the radial direction, the rotor magnet  33  faces the stator  34  in the radial direction with a gap interposed therebetween. 
     The impeller  20  is rotated around the central axis J by the motor  30 . The impeller  20  is made of, for example, a resin. The impeller  20  includes a plurality of blade portions  22  and the impeller cup  21 . As shown in  FIG. 2 , the plurality of blade portions  22  are located on the radial-direction outer surface of the second cylindrical portion  21   a  (described below) of the impeller cup  21 . The plurality of blade portions  22  are disposed at equal intervals around a circumference in the peripheral direction. In  FIG. 2 , the number of blade portions  22  is, for example, 5. By rotating the impeller  20 , the blade portions  22  blow air in the axial direction Z. 
     As shown in  FIG. 1 , the impeller cup  21  has a cylindrical shape that opens on both sides in the axial direction Z. The impeller cup  21  is fitted to the rotor cup  32  from an outer side in the radial direction. As shown in  FIG. 6 , the impeller cup  21  includes the second cylindrical portion  21   a , a plurality of first ribs  23   a  and a plurality of second ribs  23   b , which correspond to a plurality of ribs, a contact portion  21   b , and first protruding portions  21   c.    
     As shown in  FIG. 1 , the second cylindrical portion  21   a  has a cylindrical shape that surrounds the first cylindrical portion  32   b  on an outer side of the rotor cup  32  in the radial direction. More specifically, the second cylindrical portion  21   a  has a cylindrical shape having the central axis J as the center. As shown in  FIG. 6 , the second cylindrical portion  21   a  includes a first recessed portion  21   e  that is recessed outward in the radial direction from an inner surface of the second cylindrical portion  21   a  in the radial direction. In  FIG. 6 , the first recessed portion  21   e  is a groove that extends in the shape of a ring in the peripheral direction. The first recessed portion  21   e  is located in an axial-direction-Z center of the inner surface of the second cylindrical portion  21   a  in the radial direction. The second cylindrical portion  21   a  includes a plurality of second recessed portions  21   d  that are recessed upward from a lower end portion of the second cylindrical portion  21   a . The plurality of second recessed portions  21   d  are disposed at equal intervals around a circumference in the peripheral direction. 
     The plurality of first ribs  23   a  and the plurality of second ribs  23   b  protrude inward in the radial direction from the inner surface of the second cylindrical portion  21   a  in the radial direction. The first ribs  23   a  are located at portions of the radial-direction inner surface of the second cylindrical portion  21   a  that are on the lower side of the first recessed portion  21   e . The first ribs  23   a  extend in the axial direction Z from a lower end portion of the radial-direction inner surface of the second cylindrical portion  21   a  to a lower edge portion of the first recessed portion  21   e . The plurality of first ribs  23   a  are disposed apart from each other in the peripheral direction with gaps interposed therebetween. More specifically, the plurality of first ribs  23   a  are disposed at equal intervals around a circumference in the peripheral direction. 
     The second ribs  23   b  are located at portions of the radial-direction inner surface of the second cylindrical portion  21   a  that are on the upper side of the first recessed portion  21   e . The second ribs  23   b  extend in the axial direction Z from an upper end portion of the radial-direction inner surface of the second cylindrical portion  21   a  to an upper edge portion of the first recessed portion  21   e . The plurality of second ribs  23   b  are disposed apart from each other in the peripheral direction with gaps interposed therebetween. The plurality of second ribs  23   b  are disposed at equal intervals around a circumference in the peripheral direction. The plurality of first ribs  23   a  and the plurality of second ribs  23   b  are situated at corresponding positions in the peripheral direction. 
     The plurality of first ribs  23   a  and the plurality of second ribs  23   b  are in contact with an outer surface of the first cylindrical portion  32   b  in the radial direction. That is, the impeller cup  21  is in contact with an outer surface of the rotor cup  32  in the radial direction with the plurality of first ribs  23   a  and the plurality of second ribs  23   b  interposed therebetween. This allows the contact area between the impeller cup  21  and the outer surface of the rotor cup  32  in the radial direction to be reduced. Therefore, when, for example, the thermal expansion coefficient of the impeller cup  21  and the thermal expansion coefficient of the rotor cup  32  differ from each other, it is possible to reduce a stress that is produced between the rotor cup and the impeller cup  21  by thermal expansion or thermal contraction. Consequently, it is possible to suppress damage to the impeller cup  21  and the rotor cup  32 . 
     Specifically, when the impeller  20  is made of a resin and the rotor cup  32  is made of a metal, for example, the thermal expansion coefficient of the impeller  20  is larger than the thermal expansion coefficient of the rotor cup  32 . In this case, for example, when the blower  10  is placed under a low-temperature environment, the deformation amount resulting from the thermal contraction of the impeller cup  21  is larger than the deformation amount resulting from the thermal contraction of the rotor cup  32 . Even in this case, since it is possible to reduce a stress that is produced in the impeller cup  21  as mentioned above, it is possible to suppress damage to the impeller cup  21  made of a resin. 
     As shown in  FIG. 4 , the contact portion  21   b  protrudes towards the inner side in the radial direction from an upper portion of the second cylindrical portion  21   a . More specifically, the contact portion  21   b  protrudes inward in the radial direction from an upper end portion of the second cylindrical portion  21   a . As shown in  FIG. 6 , the contact portion  21   b  includes a ring-shaped portion  21   f  and a plurality of third ribs  23   c . The ring-shaped portion  21   f  has a ring shape having the central axis J as the center. An outer edge portion of the ring-shaped portion  21   f  in the radial direction is connected to the upper end portion of the second cylindrical portion  21   a . As shown in  FIG. 4 , the ring-shaped portion  21   f  is located on the upper side of the impeller supporting portion  32   h . A radial-direction inner end portion of the ring-shaped portion  21   f  faces the cover portion  32   a  in the radial direction with a gap interposed therebetween. 
     As shown in  FIG. 6 , each third rib  23   c  protrudes downward from a lower surface of the ring-shaped portion  21   f . Each third rib  23   c  extends in the radial direction. The plurality of third ribs  23   c  are disposed at equal intervals around a circumference in the peripheral direction. The plurality of third ribs  23   c  and the plurality of second ribs  23   b  are disposed at corresponding positions in the peripheral direction. An outer end portion of each third rib  23   c  in the radial direction is connected to the upper end portion of its corresponding second rib  23   b.    
     As shown in  FIG. 4 , the contact portion  21   b  is in contact with the rotor cup  32  on the upper side of the rotor cup  32 . More specifically, each third rib  23   c  is in contact with an upper surface of the impeller supporting portion  32   h . That is, the impeller cup  21  is in contact with an upper surface of the rotor cup  32  with the plurality of third ribs  23   c  interposed therebetween. This allows the contact area between the impeller cup  21  and the upper surface of the rotor cup  32  to be reduced. Therefore, for example, when the thermal expansion coefficient of the impeller cup  21  and the thermal expansion coefficient of the rotor cup  32  differ from each other, it is possible to reduce a stress that is produced between the impeller cup  21  and the rotor cup  32  by thermal expansion or thermal contraction. Consequently, it is possible to suppress damage to the impeller cup  21  and the rotor cup  32 . 
     In a state in which the contact portion  21   b  is in contact with the rotor cup  32 , the second cylindrical portion  21   a  is disposed apart from and above each flange portion  32   c . That is, each flange portion  32   c  is disposed apart from the lower side of the second cylindrical portion  21   a  with a gap interposed therebetween. Therefore, by bringing the contact portion  21   b  into contact with the impeller supporting portion  32   h , it is possible to precisely position the impeller cup  21  with respect to the rotor cup  32  in the axial direction Z. 
     Each first protruding portion  21   c  protrudes downward from the second cylindrical portion  21   a . More specifically, as shown in  FIG. 6 , each first protruding portion  21   c  protrudes downward from a downwardly facing face of an inner surface of its corresponding second recessed portion  21   d . A lower end portion of each first protruding portion  21   c  is located, for example, in correspondence with the position of the lower end portion of the second cylindrical portion  21   a  in the axial direction Z. Each first protruding portion  21   c  extends in the peripheral direction. Each first protruding portion  21   c  has the shape of a rectangular plate that is curved in the shape of an arc in the peripheral direction. 
     As shown in  FIG. 4 , at least a part of each first protruding portion  21   c  is located inside its corresponding first hole portion  35 . Therefore, for example, even if a centrifugal force or the like is applied to the impeller cup  21  and the impeller cup  21  tries to deform outward in the radial direction, each first protruding portion  21   c  is caught by an inner surface of its corresponding first hole portion  35 , such that it is possible to suppress deformation of the impeller cup  21 . This makes it possible to suppress a reduction in the air quantity characteristics of the blower  10 . In addition, it is possible to inhibit the blade portions  22  from contacting the housing  50  and to suppress damage to the blade portions  22 . Further, it is possible to suppress rotation of the impeller cup  21  with respect to the rotor cup  32  in the peripheral direction. 
     For example, in  FIG. 4 , in the radial direction, each first protruding portion  21   c  is located apart from both radial-direction faces of the inner surface of its corresponding first hole portion  35 . When the impeller cup  21  is deformed outward in the radial direction from this state, each first protruding portion  21   c  comes into contact with and is caught by the radial-direction outer face of the inner surface of its corresponding first hole portion  35 . This makes it possible to inhibit movement of each first protruding portion  21   c  outward in the radial direction beyond its corresponding first hole portion  35  and to suppress deformation of the impeller cup  21 . 
     In the embodiment, each flange portion  32   c  includes its corresponding first hole portion  35  and the impeller cup  21  includes its corresponding first protruding portion  21   c . Therefore, compared to when each first hole portion is formed in the impeller cup  21 , it is possible easily form each first hole portion  35  by punching out a part of each flange portion  32   c.    
     Each first protruding portion  21   c  is inserted into its corresponding first hole portion  35  from thereabove. Each first protruding portion  21   c  extends through its corresponding first hole portion  35  in the axial direction Z. The lower end portion of each first protruding portion  21   c  is located below its corresponding flange portion  32   c . Therefore, each first protruding portion  21   c  is reliably and easily caught by its corresponding first hole portion  35  and deformation of the impeller cup  21  can be further suppressed. In addition, for example, a weight for adjusting the center-of-gravity balance may be mounted on the lower end portion of each first protruding portion  21   c.    
     In the embodiment, the burrs  32   e  that are formed when the first hole portions  35  are punched out by using a press die are located on the lower surfaces of the respective flange portions  32   c . Therefore, compared to when the burrs  32   e  are formed on upper surfaces of the respective flange portions  32   c , the burrs  32   e  do not inhibit the insertions of the corresponding first protruding portions  21   c  and the first protruding portions  21   c  are easily inserted into the corresponding first hole portions  35  from thereabove. 
     As shown in  FIG. 2 , in a state in which the first protruding portions  21   c  have been inserted, a part of each flange portion  32   c  is located in its corresponding second recessed portion  21   d . In the embodiment, the impeller cup  21  includes the plurality of first protruding portions  21   c . As shown in  FIG. 6 , each of the plurality of first protruding portions  21   c  protrudes downward from the downwardly facing surface of the inner surface of a corresponding one of the plurality of second recessed portions  21   d.    
     As shown in  FIG. 2 , each of the plurality of first protruding portions  21   c  is inserted into a corresponding one of the plurality of first hole portions  35 . This makes it possible to further suppress deformation of the impeller cup  21 . The number of first protruding portions  21   c  is the same as the number of blade portions  22 . In  FIG. 2 , for example, the number of first protruding portions  21   c  is 5. The plurality of first protruding portions  21   c  are disposed at equal intervals around a circumference in the peripheral direction. 
     For example, portions of the second cylindrical portion  21   a  that are connected to the blade portions  22 , in particular, tend to be deformed than other portions of the second cylindrical portion  21   a  due to the self-weight of each blade portion  22 . On the other hand, in the embodiment, in the peripheral direction, at least a part of each first hole portion  35  and at least a part of its corresponding first protruding portion  21   c  overlap the position of the portion of the second cylindrical portion  21   a  that is connected to its corresponding blade portion  22 . Therefore, it is possible to suitably suppress deformation of the portions of the second cylindrical portion  21   a  that, in particular, tend to be deformed and to further suppress deformation of the impeller cup  21 . In the embodiment, in the peripheral direction, the first hole portions  35  and the first protruding portions  21   c  in their entirety overlap the positions of the corresponding portions of the second cylindrical portion  21   a  that are connected to the corresponding blade portions  22 . 
     As shown in  FIG. 4 , in the embodiment, the impeller cup  21  is fixed to the rotor cup  32  with an adhesive  70 . The adhesive  70  is placed at a location between each portion of the radial-direction inner surface of the second cylindrical portion  21   a  where the corresponding first ribs  23   a  are adjacent to each other in the peripheral direction and the radial-direction outer surface of the first cylindrical portion  32   b , is placed at a location between each portion of the radial-direction inner surface of the second cylindrical portion  21   a  where the corresponding second ribs  23   b  are adjacent to each other in the peripheral direction and the radial-direction outer surface of the first cylindrical portion  32   b , and is placed inside the first recessed portion  21   e . That is, the adhesive  70  that adheres the inner surface of the second cylindrical portion  21   a  in the radial direction and the outer surface of the first cylindrical portion  32   b  in the radial direction to each other is placed inside the first recessed portion  21   e . Therefore, the adhesive  70  that is placed inside the first recessed portion  21   e  functions as a stopper and is capable of inhibiting the impeller cup  21  from moving and coming off the rotor cup  32  in the axial direction Z. 
     As shown in  FIG. 1 , the circuit board  80  has a plate shape that extends in the radial direction. The circuit board  80  is fixed to the stator  34  on the lower side of the stator  34 . The circuit board  80  is electrically connected to the motor  30 . 
     The housing  50  is disposed outward of the motor supporting section  40  in the radial direction. The housing  50  has a cylindrical shape that extends in the axial direction Z. On an outer side of the impeller  20  and the motor  30  in the radial direction, the housing  50  surrounds the impeller  20  and the motor  30 . A lower end portion of the housing  50  is connected to the motor supporting section  40  by a plurality of connection ribs  51 . 
     The present disclosure is not limited to the above-described embodiment, such that other structures may be used. In the description below, structures that correspond to those of the above-described embodiment are, for example, given the same reference numerals as appropriate and are sometimes not described. 
     As shown in  FIGS. 7 and 8 , in a blower  110  of the embodiment, a cover portion  132   a  of a rotor cup  132  includes second hole portions  132   i  that are recessed downward from an upper surface of the cover portion  132   a . The second hole portions  132   i  are located on an outer edge portion of the cover portion  132   a  in the radial direction. The second hole portions  132   i  extend through the cover portion  132   a  in the axial direction Z. The second hole portions  132   i  extend from the outer edge portion of the cover portion  132   a  in the radial direction to an upper end portion of a first cylindrical portion  32   b . In the embodiment, the rotor cup  132  includes, for example, the plurality of second hole portions  132   i . The plurality of second hole portions  132   i  are disposed at equal intervals around a circumference in the peripheral direction. The number of second hole portions  132   i  is, for example, 10. 
     As shown in  FIGS. 8 and 9 , each flange portion  132   c  includes a flange-portion main body  137   a  and a first protruding portion  137   b . As shown in  FIG. 8 , each flange-portion main body  137   a  protrudes outward in the radial direction from a lower portion of the first cylindrical portion  32   b . More specifically, each flange-portion main body  137   a  protrudes outward in the radial direction from a lower end portion of the first cylindrical portion  32   b . As shown in  FIG. 9 , the dimension of each flange-portion main body  137   a  in the peripheral direction increases from its inner side in the radial direction towards its outer side in the radial direction. Two edge portions  132   d  on respective peripheral-direction sides of each flange-portion main body  137   a  extend linearly in the radial direction. 
     As shown in  FIG. 8 , each first protruding portion  137   b  protrudes upward from an outer end portion of its corresponding flange-portion main body  137   a  in the radial direction. Each first protruding portion  137   b  extends in the peripheral direction. Each first protruding portion  137   b  has the shape of a rectangular plate that is curved in the shape of an arc in the peripheral direction. The dimension of each first protruding portion  137   b  in the peripheral direction is the same as the dimension in the peripheral direction at the outer end portion of its corresponding flange-portion main body  137   a  in the radial direction. 
     As shown in  FIG. 10 , in an impeller  120  of the embodiment, a second cylindrical portion  121   a  of an impeller cup  121  includes a main body portion  121   f , an inner cylindrical portion  121   g , and an outer cylindrical portion  121   h . The main body portion  121   f  has a cylindrical shape that extends in the axial direction Z having the central axis J as the center. The inner cylindrical portion  121   g  has a cylindrical shape that extends downward from an inner edge portion of the main body portion  121   f  in the radial direction. A lower end portion of the inner cylindrical portion  121   g  is in contact with an upper surface of each flange-portion main body  137   a.    
     The outer cylindrical portion  121   h  has a cylindrical shape that extends downward from an outer edge portion of the main body portion  121   f  in the radial direction. The outer cylindrical portion  121   h  is disposed apart from and outward of the inner cylindrical portion  121   g  in the radial direction. A lower end portion of the outer cylindrical portion  121   h  is located below the lower end portion of the inner cylindrical portion  121   g . The lower end portion of the outer cylindrical portion  121   h  is located below each flange portion  132   c.    
     Each first hole portion  121   i  that is recessed upwards from a lower end portion of the second cylindrical portion  121   a  is formed by the main body portion  121   f , the inner cylindrical portion  121   g , and the outer cylindrical portion  121   h . That is, the impeller cup  121  includes the first hole portions  121   i . Each first hole portion  121   i  is a hole having a bottom portion. At least a part of each first protruding portion  137   b  is located inside its corresponding first hole portion  121   i . Similarly to the first embodiment, this makes it possible to suppress deformation of the impeller cup  121 . 
     In this way, in the embodiment, the impeller cup  121  includes the first hole portions  121   i  and each flange portion  132   c  includes its corresponding first protruding portion  137   b . Therefore, for example, compared to when a first hole portion is formed in each flange portion, the dimension of each flange portion  132   c  in the radial direction is easily reduced. This makes it easy to reduce the dimension of the blower  110  in the radial direction. In  FIG. 10 , each first protruding portion  137   b  is located in its entirety inside its corresponding first hole portion  121   i . Each first protruding portion  137   b  is located between the inner cylindrical portion  121   g  and the outer cylindrical portion  121   h  in the radial direction. In  FIG. 10 , each first protruding portion  137   b  is located apart from the inner cylindrical portion  121   g  and the outer cylindrical portion  121   h  in the radial direction. 
     In the embodiment, since each first protruding portion  137   b  is formed so as to protrude upward from an outer end portion of its corresponding flange portion  132   c  in the radial direction, the outer end portion of each flange portion  132   c  in the radial direction can be disposed at a location that overlaps the position of its corresponding first hole portion  121   i  as viewed from thereabove. In the radial direction, this allows the outer end portion of each flange portion  132   c  in the radial direction to be disposed inward of a radial-direction outer surface of the second cylindrical portion  121   a . Therefore, it is possible to suppress a reduction in the air quantity of the blower  110  and to reduce noise that is produced from the blower  110 . An upper end portion of each first protruding portion  137   b  inserted in its corresponding first hole portion  121   i  is disposed on the lower side of and apart from the bottom portion of its corresponding first hole portion  121   i.    
     As shown in  FIG. 11 , the impeller cup  121  includes second protruding portions  124 . Each second protruding portion  124  has the shape of a quadrangular prism that protrudes downward from a contact portion  121   b . As shown in  FIG. 7 , at least a part of each second protruding portion  124  is located inside its corresponding second hole portion  132   i . Therefore, even if the impeller cup  121  tries to deform outward in the radial direction, each second protruding portion  124  is caught by an inner surface of its corresponding second hole portion  132   i , such that deformation of the impeller cup  121  is further suppressed. In addition, it is possible to further suppress rotation of the impeller cup  121  with respect to the rotor cup  132  in the peripheral direction. In the embodiment, unlike the first embodiment, the contact portion  121   b  does not include third ribs. 
     In the embodiment, the impeller cup  121  includes the plurality of second protruding portions  124 . The plurality of second protruding portions  124  are disposed at equal intervals around a circumference in the peripheral direction. The plurality of second protruding portions  124  are each inserted in a corresponding one of the plurality of second hole portions  132   i . This makes it possible to further suppress deformation of the impeller cup  121 . 
     As shown in  FIG. 11 , the impeller cup  121  includes a plurality of ribs  123  that each protrudes inward in the radial direction from an inner surface of the second cylindrical portion  121   a  in the radial direction. The plurality of ribs  123  are disposed at equal intervals around a circumference in the peripheral direction. In the peripheral direction, the plurality of ribs  123  are located at positions that correspond to the positions of the plurality of second protruding portions  124  corresponding thereto. The plurality of ribs  123  extend in the axial direction Z from a lower end portion of a radial-direction inner surface of the inner cylindrical portion  121   g  to an upper end portion of a radial-direction inner surface of the main body portion  121   f . The plurality of ribs  123  are in contact with an outer peripheral surface of the first cylindrical portion  32   b . This makes it is possible to reduce a stress that is produced between the impeller cup  121  and the rotor cup  132  by thermal expansion or thermal contraction and to suppress damage to the impeller cup  121  and the rotor cup  32 . 
     In each of the above-described embodiments, the outer end portion of each flange portion in the radial direction may be located in correspondence with the position of the outer surface of the second cylindrical portion in the radial direction. Even in this case, since the outer end portion of each flange portion in the radial direction does not protrude outward of the second cylindrical portion in the radial direction, it is possible to suppress a reduction in the air quantity of the blower and to reduce noise that is produced from the blower. The outer end portion of each flange portion in the radial direction may be located outward of the radial-direction outer surface of the second cylindrical portion in the radial direction. Each flange portion may protrude outward in the radial direction from a portion on the upper side of the lower end portion of the first cylindrical portion as long as this is at the lower portion of the first cylindrical portion. 
     In the first embodiment, each first hole portion may be a hole having a bottom portion. In the second embodiment, each first hole portion may be a hole that extends through the second cylindrical portion in the axial direction Z. Although, in each of the embodiments, the structure in which either one of the flange portions and the impeller cup includes the first hole portions and the other of the flange portions and the impeller cup includes the first protruding portions is used, the present disclosure is not limited thereto. For example, the flange portions and the impeller cup may both include the first hole portions and the first protruding portions. In addition, the shape of each first protruding portion and the shape of each first hole portion are not particularly limited to certain shapes. The rotor cup need not have burrs. 
     Note that the use of the blower of each embodiment described above is not limited to certain uses. 
     Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.