Patent Publication Number: US-2019191948-A1

Title: Blowing device and vacuum cleaner provided with same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Japanese Patent Application No. 2017-244949 filed on Dec. 21, 2017. The entire contents of this application are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a blowing device and a vacuum cleaner provided with the same. 
     2. Description of the Related Art 
     Hitherto, a blowing device that includes a plurality of connection portions is known. The blowing device is mounted in a vacuum cleaner or the like. In a known electric blower, air that has been suctioned through an intake port with a rotation of an impeller passes through the impeller, a diffuser, and an inside of a bracket while cooling a stator, a rotor, and the like and is ultimately discharged to a portion external to the electric blower. 
     However, in the known electric blower, air directly enters into the bracket from the diffuser to cool the stator, the rotor, and the like. Accordingly, air blowing efficiency of the electric blower decreases. 
     SUMMARY OF THE INVENTION 
     A blowing device according to an exemplary embodiment of the present disclosure includes a motor including a rotor rotatable about a central axis extending in an up-down direction, an impeller that is fixed to the rotor and that is rotatable together with the rotor, a housing that is disposed on a radial direction outer side with respect to the motor and that houses at least a portion of the motor, a blower case disposed on the radial direction outer side with respect to the housing, and a plurality of connection portions that connect the housing and the blower case to each other in the radial direction. The plurality of connection portions include a first connection portion including a communication hole that communicates an inner portion of the housing and an outer portion of the blower case to each other. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view of a blowing device. 
         FIG. 2  is an external view of the blowing device illustrating a blower case in a transparent manner. 
         FIG. 3  is a longitudinal section illustrating a configuration example of the blowing device. 
         FIG. 4  is a cross-sectional view of the blowing device viewed in an axial direction. 
         FIG. 5A  is an enlarged view illustrating a configuration example of a communication hole. 
         FIG. 5B  is a cross-sectional view of a vicinity of the communication hole viewed in a circumferential direction. 
         FIG. 5C  is a cross-sectional view of a vicinity of the communication hole viewed from an axial direction upper side. 
         FIG. 5D  is a cross-sectional view of another configuration of a vicinity of a communication hole viewed in the circumferential direction. 
         FIG. 6  is an example of a vacuum cleaner in which the blowing device is mounted. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. Note that in the present specification, a rotation axis of a motor  110  of a blowing device  100  is referred to as a “central axis CA”, and a direction parallel to the central axis CA is referred to as an “axial direction”. A direction oriented in the axial direction from a substrate  6  described later towards an impeller  120  described later is referred to as an “axial direction upper side” that is a first side in the axial direction, and a direction oriented in the axial direction from the impeller  120  towards the substrate  6  is referred to as an “axial direction lower side” that is a second side in the axial direction. In each of the components, an end portion on the axial direction upper side is referred to as an “upper end portion”, and an end position on the axial direction upper side is referred to as an “upper end”. In each of the components, an end portion on the axial direction lower side is referred to as a “lower end portion”, and an end position on the axial direction lower side is referred to as a “lower end”. Furthermore, among the surfaces of the components, a surface oriented towards the axial direction upper side is referred to as an “upper surface”, and a surface oriented towards the axial direction lower side is referred to as an “undersurface”. 
     A direction orthogonal to the central axis CA is referred to as a “radial direction”. A direction in the radial direction oriented towards the central axis CA is referred to as a “radial direction inner side” and a direction in the radial direction distancing away from the central axis CA is referred to as a “radial direction outer side”. In each of the components, an end portion on the radial direction inner side is referred to as a “radial direction inner end portion”, and an end position on the radial direction inner side is referred to as a “radial direction inner end”. In each of the components, an end portion on the radial direction outer side is referred to as a “radial direction outer end portion”, and an end position on the radial direction outer side is referred to as a “radial direction outer end”. Furthermore, in the lateral surface of each component, a lateral surface oriented towards the radial direction inner side is referred to as a “radial direction inner lateral surface”, and a lateral surface oriented towards the radial direction outer side is referred to as a “radial direction outer lateral surface”. 
     A rotation direction of a rotor  1  about the central axis CA may be referred to as a “circumferential direction”. Furthermore, a direction in which the rotor  1  moves forward in the circumferential direction is referred to as a “forward rotation direction FRD”, and a direction in which the rotor  1  moves backwards in the circumferential direction is referred to as a “backward rotation direction BRD”. In other words, the “backward rotation direction BRD” is a direction opposite to the “forward rotation direction FRD”. In each of the components, an end portion in the forward rotation direction FRD is referred to as a “forward rotation direction end portion” and an end position in the forward rotation direction FRD is referred to as a “rotation direction front end”. Furthermore, in each of the components, an end portion in the backward rotation direction BRD is referred to as a “backward rotation direction end portion”, and an end position in the backward rotation direction BRD is referred to as a “rotation direction back end”. 
     Note that the names of the directions, the end portions, and the surfaces described above do not illustrate the actual positional relationships and directions when installed in a piece of equipment. 
     The blowing device  100  according to an exemplary embodiment of the present disclosure will be described first.  FIG. 1  is an external view of the blowing device  100 .  FIG. 2  is an external view of the blowing device  100  illustrating the blower case  32  in a transparent manner.  FIG. 3  is a longitudinal section illustrating a configuration example of the blowing device  100 .  FIG. 4  is a cross-sectional view of the blowing device  100  viewed in the axial direction. Note that  FIG. 3  illustrates a cross section structure in which the blowing device  100  is imaginarily cut along a plane including the central axis CA. Furthermore,  FIG. 4  is a cross section structure in which the blowing device  100  is imaginarily cut along a plane that is parallel to the radial direction including the dot and dash line A-A in  FIG. 3 . 
     The blowing device  100  includes the motor  110 , the impeller  120 , and a casing  3 . The impeller  120  is a vanes wheel including a plurality of vanes  121  capable of rotating about the central axis CA. The impeller  120  is provided at an upper portion of the motor  110 . The impeller  120  is capable of rotating about the central axis that extends in an up-down direction. The casing  3  houses at least a portion of the motor  110  and at least a portion of the impeller  120 . 
     The motor  110  is of an inner rotor type and drives and rotates the impeller  120 . The motor  110  includes the rotor  1 , a stator  2 , a bracket  4 , and the substrate  6 . 
     The rotor  1  is rotatable about the central axis CA extending in the up-down direction. In other words, the motor  110  includes the rotor  1  rotatable about the central axis CA that extends in the up-down direction. The rotor  1  includes a shaft  10 , a magnet  11 , and a holding member  12 . The shaft  10  is a rotating shaft that extends upwards and downwards in the axial direction. The impeller  120  is attached to the upper portion of the shaft  10 . In other words, the impeller  120  is fixed to the rotor  1  and is rotatable together with the rotor  1 . Furthermore, the vanes  121  are rotatable in the rotation direction of the rotor  1 . The magnet  11  has a tubular shape extending in the axial direction and is fixed to an outer lateral surface of the shaft  10  in the radial direction. The holding member  12  is fixed to an outer lateral surface of the magnet  11  in the radial direction. The holding member  12  is disposed on the radial direction inner side with respect to the stator  2  and opposes the stator  2  in the radial direction. 
     The motor  110  further includes the stator  2  disposed on a radial direction outer side of the rotor  1 . The stator  2  is rotated by driving the rotor  1 . The stator  2  includes a stator core  21 , an insulator  22 , and a plurality of coil portions  23 . The stator core  21  is formed of laminated steel plates that are electromagnetic steel plates laminated in the axial direction, for example, and is fixed to the casing  3 . The coil portions  23  are provided in the stator core  21  with the insulator  22  in between. In other words, the stator  2  includes the stator core  21  provided with the coil portions  23 . The stator core  21  includes a core back  21 C and teeth  21 T. As illustrated in  FIG. 4 , the core back  21 C has an annular shape surrounding the central axis CA. Not that an “annular shape” herein includes, in addition to a case in which the entire circumstance is continuously connected, a case in which a portion of the circumstance is discontinuous. Furthermore, “the core back  21 C having an annular shape” includes a case in which there are a plurality of core backs  21 C and in which the plurality of core backs  21 C are arranged in the circumferential direction. The teeth  21 T each extend in the radial direction from the core back  21 C towards the holding member  12 . The insulator  22  is, for example, an insulating member formed using a resin material and covers at least a portion of the stator core  21 , in particular, covers the teeth  21 T. The coil portions  23  are winding members formed of conducting wires wound around the teeth  21 T of the stator core  21  with the insulator  22  in between. In other words, the stator core  21  and the coil portions  23  are electrically insulated from each other with the insulator  22 . Furthermore, the plurality of coil portions  23  are arranged in the circumferential direction around the shaft  10 . 
     Furthermore, partial regions  21   a  in a radial direction outer lateral surface of the stator core  21  are in contact with and are fixed to an inner surface of the casing  3 . Hereinafter, the partial regions  21   a  are referred to as “stator first regions  21   a ”. Furthermore, other partial regions  21   b  in the radial direction outer lateral surface of the stator core  21  that oppose the inner surface of the casing  3  in the radial direction with gaps  110   a  in between are referred to as “stator second regions  21   b ”. In other words, the radial direction outer lateral surface of the stator core  21  includes the stator first regions  21   a  and the stator second regions  21   b . In the present embodiment, in the stator first regions  21   a , portions of a radial direction outer end portion of the core back  21 C are in contact with and are fixed to a radial direction inner lateral surface of a cylindrical portion  312  of a motor housing  31 , described later, of the casing  3 . 
     The bracket  4  includes a lower bearing holder  41  and a lid portion  42 . The lower bearing holder  41  rotatably supports the shaft  10  with a lower bearing  41   a  interposed therebetween. Furthermore, the lower bearing holder  41  has a tubular shape extending in the axial direction. The lower bearing  41   a  is provided on a radial direction inner lateral surface of the lower bearing holder  41 . The shaft  10  passes through both the lower bearing  41   a  and the lower bearing holder  41 . Although not limited to any bearing in particular, a ball bearing, a sleeve bearing, or the like can be used as the lower bearing  41   a . The lid portion  42  extends towards the radial direction outer side from a lower end portion of the lower bearing holder  41  and covers an opening at a lower end portion of the casing  3 . 
     In the present embodiment, the substrate  6  is disposed below the bracket  4  in the axial direction and is fixed to the lid portion  42  of the bracket  4 . The substrate  6  is a plate-shaped circuit substrate and is formed of a resin material such as an epoxy resin. The substrate  6  is electrically connected to the coil portions  23  of the stator  2 . The substrate  6  is electrically connected to a device and the like external to the motor  110  through a connection line (not shown) that is drawn out to the outside of the motor  110 . Furthermore, an electronic component  61  is mounted on the substrate  6 . Furthermore, the electronic component  61  includes a power supply circuit and a control circuit of the motor  110 . 
     The casing  3  includes the motor housing  31 , the blower case  32 , and a plurality of connection portions  33 . In other words, the blowing device  100  includes the motor housing  31 , the blower case  32 , and the plurality of connection portions  33 . The motor housing  31 , the blower case  32 , and the connection portions  33  constitute the same member in the present embodiment, in other words, the motor housing  31 , the blower case  32 , and the connection portions  33  are an integral structure. However, not limited to the above example, at least one of the above may be a separate member, in other words, the above do not have to be an integral structure. Furthermore, communication holes  3   a  are provided in the casing  3 . The configuration of the communication holes  3   a  will be described later. 
     The motor housing  31  houses at least a portion of the motor  110 . In the present embodiment, the motor housing  31  houses the rotor  1  and the stator  2 . The motor housing  31  has a tubular shape with a lid. The motor housing  31  includes an upper bearing holder  311  and the cylindrical portion  312 . 
     The upper bearing holder  311  rotatably supports the shaft  10  with an upper bearing  311   a  interposed therebetween. Furthermore, the upper bearing holder  311  extends in the radial direction. The upper bearing holder  311  is, at the center provided, with a through hole  311   b  that penetrates thereof in the axial direction. The upper bearing  311   a  is provided on a radial direction inner lateral surface of the through hole  311   b . The shaft  10  is inserted in the upper bearing  311   a  together with the through hole  311   b . Although not limited to any bearing in particular, a ball bearing, a sleeve bearing, or the like can be used as the upper bearing  311   a.    
     The cylindrical portion  312  extends downwards in the axial direction from a radial direction outer end portion of the upper bearing holder  311 . The cylindrical portion  312  is disposed on the radial direction outer side with respect to the motor  110 . In other words, the motor housing  31  is disposed on the radial direction outer side with respect to the motor  110 . The radial direction inner lateral surface of the cylindrical portion  312  is, in the radial direction outer lateral surface of the stator core  21 , in contact with the stator first regions  21   a  and is separated from the stator second regions  21   b  in the radial direction. In other words, the stator first regions  21   a  are in contact with the inner surface of the motor housing  31 . Furthermore, the stator second regions  21   b  having the gaps  110   a  in the radial direction oppose the inner surface of the motor housing  31 . 
     The blower case  32  houses the impeller  120 . The blower case  32  is disposed on a radial direction outer side of the motor housing  31 . An intake port  32   a  is provided at an upper end portion of the blower case  32 . The blower case  32  forms a gap with the motor housing  31 . The gap is a distribution passage of the airflow generated by the rotation of the impeller  120 . A ventilation port  32   b  is provided at a lower end portion of the blower case  32  and between a radial direction outer lateral surface of the motor housing  31 . The air drawn in through the intake port  32   a  with the rotation of the impeller  120  flows downwards in the axial direction through a portion between the motor housing  31  and the blower case  32  and is sent out to a portion outside the casing  3  through the ventilation port  32   b.    
     The connection portions  33  connect the motor housing  31  and the blower case  32  to each other in the radial direction. Inner end portions of the connection portions  33  are connected to the radial direction outer lateral surface of the motor housing  31 . Radial direction outer end portions of the connection portions  33  are connected to a radial direction inner lateral surface of the blower case  32 . 
     Furthermore, the connection portions  33  are stator blades disposed between the motor housing  31  and the blower case and are arranged in a plural number in the circumferential direction. Each of the connection portions  33  extends in the axial direction. As upper end portions of the connection portions  33  extend towards the axial direction upper side, the upper end portions curve towards the backward rotation direction BRD. Accordingly, the airflow generated by the rotation of the impeller  120  easily flows between adjacent connection portions  33  in the circumferential direction. 
     A configuration of the communication holes  3   a  will be described next.  FIG. 5A  is an enlarged view illustrating a configuration example of the communication hole  3   a .  FIG. 5B  is a cross-sectional view of a vicinity of the communication hole  3   a  viewed in the circumferential direction.  FIG. 5C  is a cross-sectional view of a vicinity of the communication hole  3   a  viewed from the axial direction upper side.  FIG. 5D  is a cross-sectional view of another configuration of a vicinity of the communication hole  3   a  viewed in the circumferential direction. Note that  FIG. 5A  corresponds to a portion surrounded by a dot and dash line in  FIG. 1 . Furthermore, in order to facilitate understanding of the configuration, the blower case  32  is depicted in a transparent manner in  FIG. 5A .  FIGS. 5B and 5D  illustrate cross section structures taken along a dot and dash line B-B in  FIG. 5A .  FIG. 5C  illustrates a cross section structure taken along a dot and dash line C-C in  FIG. 5A . 
     As described above, the communication holes  3   a  are provided in the casing  3 . When viewed in the radial direction, each communication hole  3   a  is, among the plurality of connection portions  33 , formed inside a corresponding single connection portion  7 . More specifically, when viewed in the radial direction, the communication hole  3   a  is formed between a forward rotation direction end portion and a backward rotation direction end portion of the connection portion  7 , and between an upper end and a lower end of the connection portion  7 . Furthermore, when viewed in the circumferential direction, a radial direction inner end portion of the communication hole  3   a  penetrates the cylindrical portion  312  of the motor housing  31  in the radial direction, a radial direction middle portion of the communication hole  3   a  penetrates a first connection portion  7  in the radial direction, and a radial direction outer end portion of the communication hole  3   a  penetrates the blower case  32  in the radial direction. As described above, the plurality of connection portions  33  include the first connection portions  7  constituting the communication holes  3   a . Hereinafter, the connection portion  7  is referred to as a “first connection portion  7 ”. Note that among the plurality of connection portions  33 , connection portions  331  other than the first connection portions  7  are referred to as “second connection portions  331 ”. 
     In the upper portion of the first connection portion  7 , a forward rotation direction lateral surface  7   a  of the first connection portion  7  is a curved surface that extends downwards in the axial direction as the lateral surface  7   a  extends in the forward rotation direction FRD. In the upper portion of the first connection portion  7 , a backward rotation direction lateral surface  7   b  of the first connection portion  7  is a curved surface that extends downwards in the axial direction as the lateral surface  7   a  extends in the forward rotation direction FRD. Furthermore, the forward rotation direction lateral surface  7   a  protrude in the forward rotation direction FRD and towards the axial direction upper side. Furthermore, the backward rotation direction lateral surface  7   b  is recessed in the forward rotation direction FRD and towards the axial direction upper side. With the curve of the forward rotation direction lateral surface  7   a  described above, the airflow can be distributed in a smooth manner between the first connection portion  7  and the connection portion adjacent to the first connection portion  7  in the forward rotation direction FRD. Furthermore, with the curve of the backward rotation direction lateral surface  7   b  described above, the airflow can be distributed in a smooth manner between the first connection portion  7  and the connection portion  33  adjacent to the first connection portion  7  in the backward rotation direction BRD. Accordingly, the air blowing efficiency of the blowing device  100  can be improved. 
     As described above, each communication hole  3   a  penetrates the cylindrical portion  312  of the motor housing  31 , the corresponding first connection portion  7 , and the blower case  32  in the radial direction. In other words, each communication hole  3   a  communicates the inside of the motor housing  31  and the outside of the blower case  32  to each other. As illustrated in  FIG. 4 , the communication holes  3   a  are connected to the gaps  110   a  between the stator second regions  21   b  in the radial direction outer lateral surface of the stator core  21  and the inner surface of the cylindrical portion  312  of the motor housing  31 . The gaps  110   a  are in communication with the outside of the blowing device  100  through a lower end portion of the motor housing  31 . By providing the communication holes  3   a  in the casing  3 , the inside of the motor housing  31  and the outside of the blower case  32  are in communication with each other through the communication holes  3   a . Accordingly, air can be distributed between the inside of the motor housing  31  and the outside of the blower case  32  through the communication holes  3   a . For example, a portion of the airflow that flows between the first connection portion  7  and the connection portion  33  adjacent to the first connection portion  7  and that is discharged towards the axial direction lower side flows into the motor housing  31  through the lower end portion of the motor housing  31  and is discharged to the outside of the blower case  32  through the communication holes  3   a . Furthermore, such a circulation of the airflow does not have an adverse effect on the airflow that is generated by the rotation of the impeller  120  and that flows into the portion between the first connection portion  7  and the connection portion  33  adjacent to the first connection portion  7  in the circumferential direction. Accordingly, the motor  110  can be cooled by the above airflow without decreasing the air blowing efficiency. 
     Furthermore, an opening region at the radial direction inner end of each communication hole  3   a  overlaps a portion of the motor  110  in the radial direction. More specifically, the opening region at the radial direction inner end of each communication hole  3   a  overlaps a portion of the stator  2  in the radial direction. Note that the opening region at the radial direction inner end of each communication hole  3   a  is the radial direction inner end portion of the communication hole  3   a  that is open in the inner surface of the cylindrical portion  312  of the motor housing  31 . In other words, in the inner surface of the cylindrical portion  312  of the motor housing  31 , each communication hole  3   a  is open towards a portion of the motor  110  and, when viewed in the radial direction, overlaps a portion of the motor  110 . More specifically, each communication hole  3   a  opens towards a portion of the stator  2  and overlaps a portion of the stator  2 . With such a configuration, each communication hole  3   a  open in the inner surface of the motor housing  31  directly faces a portion of the motor  110  such as, for example, the stator  2  or, more specifically, directly faces a portion of the stator  2  such as, for example, the stator core  21 . Accordingly, the motor  110  can be cooled by the airflow discharged from between a portion of the motor  110  and the motor housing  31  to the outside of the blower case  32  through the communication holes  3   a , for example. 
     In the present embodiment, the communication holes  3   a  overlap portions of the stator second regions  21   b  of the stator  2  in the radial direction and, in particular, overlap portions of radial direction outer lateral surfaces of the core back  21 C in the stator second regions  21   b  in the radial direction. In other words, the opening region in the radial direction inner end of each communication hole  3   a  overlaps a portion of the corresponding stator second region  21   b  in the radial direction. With the above configuration, the flow of the airflow flowing into the inside of the motor housing  31  from the axial direction lower side of the motor housing  31  is facilitated by having the communication holes  3   a  be in communication with the gap between the motor housing  31  and the stator  2 ; accordingly, the cooling efficiency of the stator  2  is improved. 
     Note that in the present embodiment, as illustrated in  FIG. 5B , for example, the stator  2  is not in contact with the motor housing  31  at positions that are the same as those of the stator second regions  21   b  in the circumferential direction. However, not limited to the example described above, as illustrated in  FIG. 5D , at a position that is the same as that of the stator second region  21   b  in the circumferential direction, a portion of the stator  2  may be in contact with the motor housing  31  at a portion on the axial direction lower side with respect to the communication hole  3   a . For example, in  FIG. 5D , a portion of the insulator  22  on the axial direction lower side with respect to the communication hole  3   a  covers an axial direction lower portion of the stator core  21  and is in contact with the motor housing  31 . Accordingly, the gap  110   a  is closed on the axial direction lower side with respect to the communication hole  3   a . With the above configuration, among the surfaces of the stator  2 , a portion of a surface region  22   a  of the insulator  22  disposed on the axial direction lower side with respect to the stator second region  21   b  is in contact with the motor housing  31 . Hereinafter, each of the above surface region  22   a  is referred to as a “stator third region  22   a ”. Note that in  FIG. 5D , in the stator third region  22   a , only the above-described portion of the radial direction outer lateral surface of the insulator  22  is in contact with the motor housing  31 . However, not limited to the example described above, the entire stator third region  22   a  may be in contact with the motor housing  31 . Such a configuration can be provided by having the stator second region  21   b  have a tapered shape that is tapered towards the radial direction outer side as the stator second region  21   b  extends towards the axial direction lower side. As described above, the surface of the stator  2  includes the stator third region  22   a  in which a portion thereof is in contact with the motor housing  31  on at least the axial direction lower side with respect to the communication hole  3   a . The stator third region  22   a  is disposed on the axial direction lower side of the stator second region  21   b . In other words, the stator  2  further includes the stator third region  22   a  disposed on the axial direction lower side of the stator second region  21   b . At least a portion of each stator third region  22   a  is in contact with the motor housing  31 . According to the above configuration, each gap  110   a  is closed at the axial direction lower side with respect to the corresponding communication hole  3   a  by a portion of the stator  2  that includes the stator third region  22   a  on the surface thereof. Accordingly, the airflow inside the casing  3  that flows into the gaps  110   a  from the axial direction upper side of the stator core  21  can be sent out to the outside of the casing  3  through the communication holes  3   a . In other words, compared with a case in which the gaps  110   a  are not closed by the stator third regions  22   a , the air inside the casing  3  can be prevented from being guided to the communication holes  3   a  without passing through the gaps  110   a  and cooling the axial direction upper side region of the stator core  21 . Accordingly, the stator core  21  can be cooled more efficiently. 
     Furthermore, the upper end of the opening region in the radial direction inner end of each communication hole  3   a  is, as illustrated in  FIG. 5B , disposed on the axial direction upper side with respect to the upper end of the stator core  21 . With the above configuration, since the upper end of each communication hole  3   a  is situated above the stator core  21  in the axial direction, the air above the stator core  21  in the axial direction can be guided to the communication hole in an efficient manner. 
     As the bores of the communication holes  3   a  become larger, the airflow flows more easily from the inside to the outside of the casing  3  through the communication holes  3   a . Accordingly, desirably as illustrated in  FIG. 5A , a width W 1  of the first connection portion  7  in the circumferential direction is larger than a width W 2  of the second connection portions  331 , which are connection portions other than the first connection portion  7  among the plurality of connection portions  33 , in the circumferential direction. With the above configuration, the widths of the communication holes  3   a  in the circumferential direction can be enlarged. Accordingly, an improvement in the cooling effect of the motor  110  can be achieved. 
     Furthermore, desirably, a largest width Wam of each communication hole  3   a  in the axial direction is larger than a largest width Wrm of the communication hole  3   a  in the circumferential direction (see  FIG. 1 ). In other words, desirably, in each communication hole  3   a , the axial direction is the longitudinal direction and the circumferential direction is the short direction. With the above configuration, for example, the airflow that flows into the motor housing  31  from the axial direction lower side of the motor housing  31  and that is discharged through the communication holes  3   a  is in contact with the motor  110  longer. Accordingly, the motor  110  can be cooled more effectively. 
     While the arrangement of the communication holes  3   a  is not limited to any arrangement in particular, desirably, the communication holes  3   a  are provided in a plural number and at equal distances in the circumferential direction. Accordingly, the first connection portions  7  in which the communication holes  3   a  are provided are, desirably, provided in a plural number and at equal distances are in the circumferential direction. With the above configuration, since the communication holes  3   a  provided inside the first connection portions  7  are disposed at equal distances in the circumferential direction, the motor  110  can be cooled evenly in the circumferential direction. Furthermore, while the number of communication holes  3   a  and the number of first connection portions  7  are each three in the present embodiment, not limited to the example described above, the numbers may each be one or a plural number other than three. 
     An example in which the blowing device  100  described above is mounted in a vacuum cleaner  200  will be described next.  FIG. 6  is a perspective view illustrating a configuration of the vacuum cleaner  200  in which the blowing device  100  is mounted. The vacuum cleaner  200  includes the blowing device  100 . In more detail, the vacuum cleaner  200  includes the blowing device  100 , a nozzle  210 , and a main body  220 . The blowing device  100  is mounted in the main body  220 . A suction brush (not shown) is attached to an intake portion  211  of the nozzle  210 . The main body  220  includes a dust chamber  221  connected to the nozzle  210 , a housing chamber  222  in which the blowing device  100  is housed, and an exhaust space  223  connected to a plurality of exhaust ports (not shown). An opening portion of the blowing device  100  is connected to the dust chamber  221  with a dust connection filter (not shown) interposed therebetween. In other words, a flow passage of the air suctioned by the blowing device  100  is connected from the intake portion  211 , through the nozzle  210  and the dust chamber  221 , and to the opening portion of the blowing device  100  in the above order. The housing chamber  222  is connected to the exhaust space  223 . The airflow sent out with the blowing device  100  is discharged to the outside of the main body  220  through the exhaust space  223  and through the exhaust ports. With the above, the vacuum cleaner  200  including the blowing device  100  capable of effectively suppressing the air blowing efficiency from decreasing can be attained. 
     Note that the blowing device  100  in  FIG. 6  is mounted in a stick-type vacuum cleaner  200 ; however, not limited to the example of the present embodiment described above, the blowing device  100  may be mounted in a vacuum cleaner of another type. For example, the vacuum cleaner  200  may be, for example, a vacuum cleaner of a canister type or of a handy type. 
     The present disclosure is suitable for an apparatus that suctions or sends out gas and that is required to have a high static pressure, for example. The present disclosure can be used in blowing devices other than a vacuum cleaner (see  FIG. 6 ) such as an electric fan or a ventilation fan and, further, can be used in electrical appliances for other purposes such as a drying device. 
     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.