BLOWING DEVICE, AND VACUUM CLEANER

A blowing device according to an exemplary embodiment of the present disclosure includes a motor that includes a shaft disposed along a central axis extending in an up-down direction, an impeller fixed to the shaft, the impeller being disposed above the motor, an impeller cover that surrounds an upper side and an outer side in a radial direction of the impeller, the impeller cover including an intake port at a middle, a motor cover disposed on an outer side in a radial direction of the motor. The motor includes a rotor portion fixed to the shaft, the rotor portion including a magnet, a stator portion that opposes the magnet, and a bearing that rotatably supports the shaft with respect to the stator portion. The motor cover includes a tubular motor cover cylindrical portion that is open downwards. An inner surface of the motor cover cylindrical portion opposes the motor with a gap in between in the radial direction. The motor cover cylindrical portion includes a communication portion that communicates an inner space of the motor cover cylindrical portion and an outer space of the motor cover cylindrical portion to each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure is related to a blowing device and a vacuum cleaner.

2. Description of the Related Art

Hitherto, there is known an electric blower that is capable of cooling a drive semiconductor element. An electric blower distributes air that has been generated by an impeller and that has been guided by an air guide along a ventilation passage formed between an outer cylinder and a frame, and claims that a compact, efficient, and low-noise cooling mechanism can be obtained by attaching a drive semiconductor element to the outer cylinder.

However, in the electric blower, the air that has flowed along the ventilation passage does not flow into an inside of the frame; accordingly, there is a problem in that the motor cannot be efficiently cooled.

SUMMARY OF THE INVENTION

A blowing device according to an exemplary embodiment of the present disclosure includes a motor that includes a shaft disposed along a central axis extending in an up-down direction, an impeller fixed to the shaft, the impeller being disposed above the motor, an impeller cover that surrounds an upper side and an outer side in a radial direction of the impeller, the impeller cover including an intake port at a middle, a motor cover disposed on an outer side in a radial direction of the motor, the motor including a rotor portion fixed to the shaft, the rotor portion including a magnet, a stator portion that opposes the magnet, and a bearing that rotatably supports the shaft with respect to the stator portion, the motor cover including a tubular motor cover cylindrical portion that is open downwards, an inner surface of the motor cover cylindrical portion opposing the motor with a gap in between in the radial direction, and the motor cover cylindrical portion including a communication portion that communicates an inner space of the motor cover cylindrical portion and an outer space of the motor cover cylindrical portion to each other.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, referring to the drawings, a blowing device according to exemplary embodiments of the present disclosure will be described. In the description hereinafter, the direction in which a central axis J extends is referred to as an axial direction. Furthermore, the upper side in the axial direction is merely referred to as an upper side and the lower side in the axial direction is merely referred to as a lower side. Note that the axial direction, an up-down direction, the upper side, and the lower side are terms that are used merely for description and do not limit the actual positional relationships and directions. Furthermore, unless otherwise stated, a direction parallel to the central axis J is merely referred to as the “axial direction”, a radial direction having the central axis J as the center is merely referred to as a “radial direction”, and a circumferential direction about the central axis J is merely referred to as a “circumferential direction”. Note that in the description hereinafter, for convenience sake, slanted lines in the cross sections and lines that illustrate partial structures may be omitted.

Hereinafter, a blowing device1according to an exemplary first embodiment of the present disclosure will be described.FIG. 1is a perspective view of the blowing device1viewed from above. The blowing device1includes an impeller cover60, a blower cover74, and an impeller50.

FIG. 2is a longitudinal section of the blowing device1of the first embodiment. The blowing device1includes a motor10, the impeller50, the impeller cover60, and a motor cover70. The motor10includes a shaft11disposed along the vertically extending central axis J. The motor10includes a rotor portion20, a stator portion30, and bearings40. The bearings40rotatably supports the shaft11with respect to the stator portion30.

The rotor portion20includes a rotor holder21that is fixed to the shaft11and that has a lidded cylindrical shape having an opening on the upper side. In the present embodiment, the rotor holder21is directly fixed to the shaft11. However, the rotor holder21may be fixed to the shaft11with another member interposed therebetween.

The rotor holder21includes a rotor holder cylindrical portion22and a rotor holder bottom portion23. The rotor holder cylindrical portion22is a tubular portion extending in the axial direction. A magnet24is fixed to an inner circumferential surface of the rotor holder cylindrical portion22. In other words, the rotor portion20is fixed to the shaft11and includes the magnet24. The magnet24has a cylindrical shape.

The rotor holder bottom portion23is disposed below the rotor holder cylindrical portion22. More specifically, the rotor holder bottom portion23is a substantially plate-shaped portion that extends inwardly from a lower end of the rotor holder cylindrical portion22.

The stator portion30opposes the magnet24. The stator portion30includes a stator core31, and coils32are each formed in the stator core31by wounding conducing wire with an insulator (not shown) interposed therebetween. In the present embodiment, the motor10is of a so-called outer rotor type. Accordingly, the magnet24is fixed to an inner circumferential surface of the rotor holder cylindrical portion22. The stator core31is disposed inside the magnet24with a gap therebetween in the radial direction.

The stator portion30includes a bearing housing33, a mounting plate34, and a circuit board36. The bearing housing33is a tubular member extending in the axial direction. A portion of the bearing housing33is fixed to a portion of a motor cover top plate portion71described later. The bearings40are fixed to an inner surface of the bearing housing33. In the present embodiment, the bearings40are ball bearings. Note that the bearings40may be slide bearings or the like.

The mounting plate34is disposed above the rotor holder21and the stator core31. The mounting plate34on the outer side with respect to the bearing housing33extends in a direction orthogonal to the shaft11. At least a portion of the mounting plate34is fixed to the bearing housing33. The mounting plate34is formed of a metal member. As illustrated inFIG. 3, the mounting plate34includes mounting plate flange portions35that protrude from the outer edge thereof in the radial direction. In the present embodiment, the mounting plate flange portions35are formed at three portions in the circumferential direction. The mounting plate flange portions35and the motor cover top plate portion71described later are fixed to each other with screws.

Returning toFIG. 2, the motor10further includes the circuit board36disposed below the mounting plate34and above the rotor holder21. The circuit board36on the outer side with respect to the bearing housing33extends in a direction orthogonal to the shaft11. In other words, an outer end of the circuit board36in the radial direction is disposed radially outside an outer end of the bearing housing33in the radial direction. An inner end of the circuit board36in the radial direction is fixed to the bearing housing33. Lead wire drawn out from each coil32is electrically connected to the circuit board36. The electric connection between the circuit board36and each lead wire is achieved by soldering, for example.

The impeller50is fixed to the shaft11and is disposed above the motor10. With the rotation of the motor10fixed to the shaft11, the impeller50rotates about the central axis J together with the shaft11. In the present embodiment, in plan view from the upper side in the axial direction, the impeller50rotates in the counterclockwise direction. In other words, in plan view from the upper side in the axial direction, a rotation direction R of the impeller is counterclockwise.

The impeller50includes a plurality of moving blades51, a main plate52, a shroud53, and a balance correcting portion54. The balance correcting portion54is formed on the shroud53. Describing in more detail, the balance correcting portion54is disposed on an upper surface of the shroud53in an external area in the radial direction.

The balance correcting portion54includes a first protrusion541and a second protrusion542. The first protrusion541is an annular portion that protrudes upwards from the upper surface of the shroud53. The second protrusion542is an annular portion that protrudes upwards from the upper surface of the shroud53. The second protrusion542is disposed on an outer side of the first protrusion541in the radial direction. In the present embodiment, the second protrusion542is disposed on an outer edge of the shroud53. With the above, a space is formed between the first protrusion541and the second protrusion542in the radial direction.

When the balance of the assembly of the motor10and the impeller50is corrected, a weight543is put in in a space between the first protrusion541and the second protrusion542in the radial direction; accordingly, the rotational balance of the assembly of the impeller50and the rotor portion20is corrected with respect to the central axis J. Note that in the present embodiment, since the balance correcting portion54is formed on the upper surface of the shroud53, the balance can be corrected easily even after the assembly has been formed. In other words, work efficiency when correcting the balance of the assembly is improved. Furthermore, since an upper end of the first protrusion541is disposed above an upper end of the second protrusion542, air can be suppressed from flowing inside the first protrusion541in the radial direction when the impeller50is rotated. In other words, the labyrinth characteristics between the upper surface of the shroud53and the impeller cover60is improved.

The plurality of moving blades51are disposed in the circumferential direction. In the present embodiment, the plurality of moving blades51include first moving blades511and second moving blades512. Inner ends of the first moving blades511in the radial direction are disposed radially inside inner ends of the second moving blades512in the radial direction. In other words, the plurality of moving blades51are constituted by two types of moving blades that have different lengths in the radial direction. In the present embodiment, the moving blades51are formed by disposing the first moving blades511and the second moving blades512in the circumferential direction. However, the plurality of moving blades51may all have the same shape or may have three types of different shapes.

The main plate52is molded as a member that is integral with the plurality of moving blades51. The main plate52is disposed below the moving blades51. Lower portions of the plurality of moving blades51are connected to the main plate52. A vertically penetrating through hole521is formed on an inner side of the main plate52. The impeller50is fixed to the shaft11through an impeller hub501fixed to the through hole521. However, the impeller50and the shaft11may be fixed to each other through another fixing method. In the present embodiment, an upper surface of the main plate52forms a curved surface that is the highest at the middle portion thereof and that, as the curved surface extends towards the outer side, spreads downwards in a smooth manner. With the above, since the air flowing from the upper side is guided along the upper surface of the main plate52towards the outer side in the radial direction, air blowing efficiency of the impeller50is improved. Note that the main plate52may have another shape and, for example, may have a flat plate shape that extends in the direction orthogonal to the shaft11.

An inner side of an underside of the main plate52is disposed above an underside of an outer edge of the main plate52. The underside of the main plate52has a curved surface that extends towards the lower side in a smooth manner as the curved surface extends from the inside to the outer side. The main plate52includes, in the underside thereof, a plurality of main plate ribs522disposed in the circumferential direction. Positions of the lower ends of the main plate ribs522in the axial direction are substantially the same as the position of the underside of the outer edge of the main plate52in the axial direction. However, the lower ends of the main plate ribs522may be positioned above the outer edge of the main plate52. The main plate ribs522are disposed more on the rear side in the rotation direction R of the impeller as the main plate ribs522extend from the inside towards the outer side. With the above, when the impeller50rotates, the main plate ribs522rotates as well in an integral manner; accordingly, the air between the main plate52and an upper surface of the motor cover top plate portion71described later can be discharged towards the outer side in the radial direction. Accordingly, a decrease in the air blowing efficiency caused by the air discharged by the rotation of the impeller50towards the outer side in the radial direction flowing into the gap between the main plate52and the motor cover top plate portion71in the axial direction can be reduced. Furthermore, the rigidity of the main plate52is increased owing to the formation of the main plate ribs522.

The shroud53is disposed above the moving blades51. The shroud53includes a through hole531that penetrates thereof in the axial direction. Upper portions of the plurality of moving blades51are connected to the shroud53. In the middle portion of the shroud53, the through hole531that penetrates thereof in the axial direction is formed. With the above, the air that has been taken in from above the impeller50passes through the through hole531of the shroud53and is taken in into the impeller50. The shroud53curves towards the lower side in a smooth manner as the shroud53extends from an inner end to the outer side. Accordingly, the air taken in into the impeller50is guided downwards and outwards in a smooth manner along the underside of the shroud53and the upper surface of the main plate52.

The impeller cover60surrounds an upper side and an outer side in the radial direction of the impeller50, and includes an intake port61at the middle thereof. With the above, the air above the blowing device1can be taken in into the blowing device1through the intake port61. The air taken in through the intake port61is taken in inside the impeller50through the through hole531formed in the shroud53.

The impeller cover60includes an impeller cover upper end portion62, an impeller cover inclination portion63, an impeller cover projecting portion64, an impeller cover cylindrical portion65, and an impeller cover guide portion66.

The impeller cover upper end portion62includes, at the middle thereof, the intake port61. The impeller cover inclination portion63extends towards the outer side and the lower side in a smooth manner from an outer side of the impeller cover upper end portion62. An underside of the impeller cover inclination portion63opposes the upper surface of the shroud53with a gap in between. The gap formed between the underside of the impeller cover inclination portion63and the upper surface of the shroud53is substantially uniform. With the above, a decrease in the air blowing efficiency of the blowing device1due to the air flowing in between the impeller cover inclination portion63and the upper shroud53can be suppressed.

The impeller cover projecting portion64projects upwards from an outer side of the impeller cover inclination portion63. The impeller cover projecting portion64is a portion that projects upwards from the outer side of the impeller cover inclination portion63. The impeller cover projecting portion64is formed in an annular manner about the central axis J. An underside of the impeller cover projecting portion64is disposed above an outer side of the underside of the impeller cover inclination portion63. In other words, in the area where the impeller cover projecting portion64is disposed, an underside of the impeller cover60is recessed towards the upper side. The balance correcting portion54is disposed in a space formed below the impeller cover projecting portion64.

The impeller cover cylindrical portion65is a tubular portion that extends downwards from an outer side of the impeller cover projecting portion64. On an outer side of an outer end of the impeller50, the impeller cover guide portion66extends downwards and outwards in the radial direction so as to form a smooth curved surface forming a convex from a lower end portion of the impeller cover cylindrical portion65towards the outer side of the impeller cover60. With the above, the air exhausted from the impeller50is guided outwards in the radial direction and downwards in a smooth manner.

The motor cover70is disposed on the outer side of the motor10in the radial direction. The motor cover70includes the motor cover top plate portion71and a motor cover cylindrical portion72. The motor cover top plate portion71is disposed above the motor10and is a plate-shaped portion that extends in a direction substantially orthogonal to the central axis J. The motor cover cylindrical portion72is a tubular portion that extends downwards from an outer side of the motor cover top plate portion71in the radial direction. The motor cover cylindrical portion72is open downwards. In other words, the motor cover70includes a tubular motor cover cylindrical portion72that open downwards.

The blower cover74is disposed on the outer side of the outer surface721of the motor cover cylindrical portion in the radial direction. The blower cover74is connected to the impeller cover guide portion66and is a tubular portion that extends downwards. The outer surface721of the motor cover cylindrical portion and an inner surface of the blower cover74oppose each other with a gap in between in the radial direction. With the above, a flow passage80is formed between the outer surface721of the impeller cover cylindrical portion and the inner surface of the blower cover74. The outer surface721of the motor cover cylindrical portion and a lower end of the blower cover74constitute an exhaust port81of the flow passage80. Accordingly, the air discharged to the outside of the impeller50in the radial direction is smoothly guided along an inner surface of the impeller cover guide portion66towards the outer side in the radial direction and towards the lower side in the axial direction, passes the flow passage80, and is discharged towards the lower side from the exhaust port81.

The motor cover70includes a plurality of stator blades73disposed on an outer surface of the motor cover cylindrical portion72in the circumferential direction. Lower portions of the stator blades73in the axial direction are disposed on the front side in the rotation direction R of the impeller with respect to the upper portions of the stator blades73in the axial direction. Describing in more detail, the upper portions of the stator blades73in the axial direction are positioned on the rear side in the rotation direction R of the impeller, and are curved downwards in a smooth manner from upper ends towards the front side in the rotation direction R of the impeller and towards the lower side, and extend downwards towards the lower portions of the stator blades73in the axial direction. With the above, the air flowing inside the flow passage80is guided towards the exhaust port81in a smooth manner. In other words, since the air discharged by the rotation of the impeller50has a swirling component in the circumferential direction oriented towards the front side in the rotation direction R of the impeller, the air having a swirling component is guided in a smooth manner towards the lower side with the stator blades73. With the above, the air blowing efficiency of the air flowing inside the flow passage80is improved.

In the present embodiment, the motor cover70, the stator blades73, and the blower cover74are formed by an integral resin member. Outer sides of the stator blades73in the radial direction are connected to the inner surface of the blower cover74. In other words, the motor cover70includes the tubular blower cover74that extends downwards from a lower end portion of the impeller cover60and that is connected to the outer ends of the stator blades73in the radial direction. Due to the above, the motor cover70, the stator blades73, and the blower cover74can be molded inexpensively as an integral member with a pair of molds that slide in the up-down direction. Furthermore, since the motor cover cylindrical portion72and the blower cover74can be formed as an integral member, compared with a case in which the cover cylindrical portion72and the blower cover74are different members, concentricity between an outer surface of the motor cover cylindrical portion72and the blower cover74is improved. Accordingly, since the width of the flow passage80in the radial direction becomes uniform in the circumferential direction, generation of pressure differences in the circumferential direction in the air flowing inside the flow passage80can be suppressed; accordingly, the air blowing efficiency of the blowing device1is improved.

The motor10is disposed on the inner side of the motor cover cylindrical portion72in the radial direction. An inner surface722of the motor cover cylindrical portion and the motor10oppose each other with a gap in between in the radial direction. With the above, either an inner rotor type motor or an outer rotor type motor can be disposed on the inner side of the motor cover cylindrical portion72in the radial direction. In the present embodiment, the motor10of the outer rotor type is disposed on the inner side of the motor cover cylindrical portion72in the radial direction. Since the motor10includes the rotor holder21that rotates, and there is a gap between the rotor holder21and the inner surface722of the motor cover cylindrical portion in the radial direction, the outer rotor type motor10can be used as a drive unit of the blowing device1.

The motor cover cylindrical portion72includes communication portions75that communicate an inner space83of the motor cover cylindrical portion and an outer space82of the motor cover cylindrical portion to each other. Furthermore, since the motor cover cylindrical portion72is open downwards, a portion of the air that has flowed downwards in the flow passage80, swirls towards the inside in the radial direction after being discharged from the exhaust port81, enters the inner space83of the motor cover cylindrical portion that fills the inner side of the motor cover cylindrical portion72in the radial direction, passes the communication portions75from the inner space83of the motor cover cylindrical portion, and is discharged to the outer space82of the motor cover cylindrical portion. Since the outer space82of the motor cover cylindrical portion is the flow passage80, the air that has been discharged to the flow passage80through the communication portions75merges with the flow of air flowing downwards inside the flow passage80, flows downwards inside the flow passage80once again, and is discharged through the exhaust port81.

The motor10is disposed in the inner space83of the motor cover cylindrical portion. Accordingly, due to the generation of heat by the coils32, a circuit element mounted on the circuit board36, and the like, a temperature of the inner space83of the motor cover cylindrical portion becomes higher than a temperature of the outer space82of the motor cover cylindrical portion. However, in the blowing device1of the present embodiment, since a portion of the air that flows in the flow passage80with the mechanism described above circulates through the inner space83of the motor cover cylindrical portion and the outer space82of the motor cover cylindrical portion through the communication portions75, a portion of the heat generated in the inner space83of the motor cover cylindrical portion can be efficiently discharged to the outer space82of the motor cover cylindrical portion. With the above, the temperature of the inner space83of the motor cover cylindrical portion is decreased, and the motor10and the circuit element mounted on the circuit board36are cooled. Furthermore, the bearing housing33and the mounting plate34are members made of metal. With the above, since the bearing housing33and the mounting plate34exceed in thermal conductivity, the heat accumulated in the bearing housing33and the mounting plate34is efficiently cooled by the air flowing in the inner space83of the motor cover cylindrical portion. Accordingly, the cooling characteristics of the motor10are improved.

Note that in the present embodiment, the outer surface721of the motor cover cylindrical portion around the lower end of the motor cover cylindrical portion72, in other words, around the exhaust port81, is disposed on the inner side in the radial direction with respect to an upper side of the motor cover cylindrical portion72, in other words, the outer surface721of the motor cover cylindrical portion in the area around where the stator blades73are disposed. Describing in more detail, the outer surface721of the motor cover cylindrical portion includes a motor cover lower area723that curves inwardly in the radial direction in a smooth manner as it extends towards the lower side. With the above, since a portion of the air flowing downwards through the flow passage80and that is discharged from the exhaust port81is smoothly guided towards the inner space83of the motor cover cylindrical portion so as to confirm the shape around the lower end of the outer surface721of the motor cover cylindrical portion, the flow of air circulating the inner space83of the motor cover cylindrical portion becomes smooth. Accordingly, the motor10disposed in the inner space83of the motor cover cylindrical portion can be cooled efficiently. Note that the motor cover lower area723may be a flat surface that is oriented inwards in the radial direction as the motor cover lower area723extends downwards.

Furthermore, in the present embodiment, the inner surface of the blower cover74is configured so as to be parallel to the axial direction. Accordingly, the width of the flow passage formed between the outer surface721of the motor cover cylindrical portion and the inner surface of the blower cover74in the radial direction is narrow in the area where the stator blades73are disposed and is the widest in the area where the exhaust port81is formed. With the above, in the area where the stator blades73are disposed, the static pressure of the air flowing in the flow passage80becomes high and, in the area where the exhaust port81is formed, the static pressure of the air becomes gradually smaller; accordingly, air resistance around the exhaust port81can be reduced. Accordingly, a generation of turbulent flow in the flow passage80can be reduced, and the air blowing efficiency of the blowing device1can be improved.

A specific configuration of the communication portions75will be described next.FIG. 3is a bottom view of the blowing device1of the first embodiment, andFIG. 4is a perspective view of the blowing device1of the first embodiment viewed from below. As illustrated inFIGS. 3 and 4, in the present embodiment, the motor cover cylindrical portion72includes cylindrical portion side wall portions76that connect the outer surface721of the motor cover cylindrical portion and the inner surface722of the motor cover cylindrical portion to each other. The cylindrical portion side wall portions76connect radial-direction outer end portions761of the cylindrical portion side wall portions and radial-direction inner end portions762of the cylindrical portion side wall portions to each other. The cylindrical portion side wall portions76are side walls of the communication portions75. The motor cover cylindrical portion72includes other cylindrical portion side wall portions76that oppose the cylindrical portion side wall portions76described above with a gap in between in the circumferential direction. The other cylindrical portion side wall portions76are side walls of the communication portions75. In other words, the motor cover cylindrical portion72includes cylindrical portion side wall portions76that connect the outer surface721of the motor cover cylindrical portion and the inner surface722of the motor cover cylindrical portion to each other and that constitute the side walls of the communication portions75. The width of each communication portion75in the circumferential direction is the same as a width in the circumferential direction between two cylindrical portion side wall portions76that oppose each other with a gap in between in the circumferential direction.

The communication portions75are formed so as to be, with respect to the radial direction, inclined in the circumferential direction. In other words, the cylindrical portion side wall portions76are, with respect to the radial direction, inclined in the circumferential direction. In the present embodiment, the radial-direction outer end portions761of the cylindrical portion side wall portions are disposed on the front side in the rotation direction R of the impeller with respect to the radial-direction inner end portions762of the cylindrical portion side wall portions. With the above, the air discharged to the outer space82of the motor cover cylindrical portion through the communication portions75includes swirling components in the circumferential direction and in the rotation direction R of the impeller. Accordingly, the air discharged through the communication portions75to the outer space82of the motor cover cylindrical portion flows in the flow passage80and can smoothly merge with the air including the swirling component in the rotation direction R of the impeller. Accordingly, the air blowing efficiency inside the flow passage80is improved. Note that sinceFIG. 3is a bottom view of the blowing device1, the rotation direction R of the impeller is clockwise.

The cylindrical portion side wall portions76are smooth curved surfaces that protrude towards the rear side in the rotation direction R of the impeller and connect the radial-direction outer end portions761of the cylindrical portion side wall portions and the radial-direction inner end portions762of the cylindrical portion side wall portions to each other. With the above, the air discharged to the outer space82of the motor cover cylindrical portion through the communication portions75is guided so as to have swirling components that are oriented towards the front side in the rotation direction R of the impeller in a smooth manner along the smooth curved surfaces that are protruded towards the rear side in the rotation direction R of the impeller. Accordingly, since merging with the air flowing in the flow passage80can be performed in a further smooth manner, the air blowing efficiency inside the flow passage80is improved. Note that the shapes of the radial-direction outer end portions761of the cylindrical portion side wall portions and the radial-direction inner end portions762of the cylindrical portion side wall portions may be chamfered surfaces or rounded shapes. With the above, a decrease in the air blowing efficiency due to generation of air vortexes around the radial-direction outer end portions761of the cylindrical portion side wall portions and the radial-direction inner end portions762of the cylindrical portion side wall portions can be reduced.

The motor cover cylindrical portion72includes cylindrical portion upper wall portions77that connect the outer surface721of the motor cover cylindrical portion and the inner surface722of the motor cover cylindrical portion to each other. The cylindrical portion upper wall portions77are side walls of the communication portions75. In other words, the motor cover cylindrical portion72includes cylindrical portion upper wall portions77that connect the outer surface721of the motor cover cylindrical portion and the inner surface722of the motor cover cylindrical portion to each other and that constitute the side walls of the communication portions75. The communication portions75are open downwards in the axial direction. In other words, the communication portions75are recesses that are recessed towards the upper side from the lower end of the motor cover cylindrical portion72. With the above, the motor cover70including the communication portions75can be formed by molds that slide in the up-down direction. Accordingly, the motor cover70can be formed inexpensively and mass-productiveness increases as well.

At least a portion of each communication portion75and at least a portion of the blower cover74oppose each other in the radial direction. With the above, the air discharged through the communication portions75to the outer space82of the motor cover cylindrical portion flows downwards along the flow passage80formed between the outer surface721of the motor cover cylindrical portion and the inner surface of the blower cover74. In other words, by having the blower cover74be disposed on the outer sides of the communication portions75in the radial direction, the wind discharged to the outer side in the radial direction through the communication portions75is guided to flow downwards inside the flow passage80without flowing outside of the flow passage80in the radial direction; accordingly, the air blowing efficiency is improved.

Radial-direction outer end portions of the cylindrical portion upper wall portions77are disposed below the lower ends of the stator blades73in the axial direction. In other words, the communication portions75are formed in areas in the flow passage80where the stator blades73are not disposed. Accordingly, compared with a case in which the communication portions75are formed in areas where the cross sections of the flow passage80are small due to the disposition of the stator blades73, since the air that has passed through the communication portions75merges in the flow passage80where the areas of the cross sections of the flow passage80are large, the pressure of the air flowing inside the flow passage80can be suppressed from becoming excessively high and a decrease in the air blowing efficiency inside the flow passage80can be suppressed. Furthermore, since the communication portions75are formed below the lower ends of the stator blades73in the axial direction, the air that has passed the communication portions75merges with the air inside the flow passage80that has been regulated downwards in the axial direction with the stator blades73; accordingly, generation of turbulent flows inside the flow passage80can be reduced.

The communication portions75are disposed in plural numbers in the circumferential direction. With the above, since the air passes the plurality of communication portions75and circulates through the inner space83of the motor cover cylindrical portion and the outer space82of the motor cover cylindrical portion, the heat of the inner space83of the motor cover cylindrical portion can be released in a further efficient manner. Furthermore, in the present embodiment, the communication portions75are disposed at equal intervals in the circumferential direction. With the above, the flow of air passing the communication portions75can be made uniform to the extent possible in the circumferential direction. Accordingly, since the flow of the air inside the flow passage80in the circumferential direction can be made uniform, the air blowing efficiency is improved.

The plurality of communication portions75may be disposed unevenly in the circumferential direction. In other words, each of the intervals between certain communication portions75and other communication portions75in the circumferential direction do not have to be the same. With the above, since the flow of the air discharged to the outer space82of the motor cover cylindrical portion through the communication portions75becomes uneven inside the flow passage80in the circumferential direction, the sonic wave generated inside the flow passage80does not easily become a standing wave that has a specific frequency; accordingly, generation of a large noise can be reduced.

The number of communication portions75, the number of moving blades51, and the number of stator blades73are, desirably, relative primes. For example, the configuration may be such that the number of communication portions75is 11, the number of moving blades51is 10, and the number of stator blades73is 27. With the above, when the impeller50rotates, resonance of the noises generated by the communication portions75, the moving blades51, and the stator blades73can be reduced and generation of noise can be reduced. Note that the number of communication portions75, the number of moving blades51, and the number of stator blades73may be relative primes of other combinations. In such a case, desirably, the number of stator blades73is the largest. With the above, since the flow of air inside the flow passage80can be regulated with a number of stator blades73, the air blowing efficiency is improved. Furthermore, desirably, the number of moving blades51is half or less than half of the number of the stator blades73. With the above, since the gap between a moving blade51and the adjacent moving blade51can be widened, the flow of air is facilitated. Furthermore, desirably, the number of communication portions75is also half or less than half of the number of stator blades73. With the above, since the cross sections of the communication portions75can be increased, the air blowing efficiency of the air flowing through the communication portions75is improved.

A blowing device1A according to a second embodiment will be described next. Note that in the description hereinafter, description of components that overlap those of the blowing device1according to the first embodiment will be omitted. Furthermore, portions and members that have the same configuration as those of the first embodiment will be given reference numerals that are the same as those of the first embodiment.

FIG. 5is a longitudinal section of the blowing device1A according to the second embodiment, andFIG. 6is a bottom view of the blowing device1A according to the second embodiment. As illustrated inFIG. 5, in the blowing device1A, a motor cover cylindrical portion72A includes communication portions75A that communicate an inner space83A of the motor cover cylindrical portion and an outer space82A of the motor cover cylindrical portion to each other. The communication portions75A are through holes that penetrate the motor cover cylindrical portion72A in the axial direction. In other words, in the communication portions75A, different from the communication portions75of the blowing device1according to the first embodiment, the communication portions75A are not cutaways open downwards but are through holes that penetrate the motor cover cylindrical portion72A in the radial direction. With the above, compared with a case in which cutaway-shaped communication portions75are formed, the rigidity of the motor cover cylindrical portion72A can be improved. Furthermore, by forming the communication portions75A, the heat generated in the inner space83A of the motor cover cylindrical portion can be efficiently discharged to the outer space82A of the motor cover cylindrical portion. The mechanism of discharging the heat generated in the inner space83A of the motor cover cylindrical portion to the outer space82A of the motor cover cylindrical portion is similar to that of the blowing device1according to the first embodiment.

In the blowing device1A, the motor cover cylindrical portion72A is constituted by a first motor cover cylindrical portion724A that extends downwards from an outer side of the motor cover top plate portion71A in the radial direction, and an annular second motor cover cylindrical portion725A that extends downwards from a lower end portion of the first motor cover cylindrical portion724A. In other words, the second motor cover cylindrical portion725A is a member that is separate from a motor cover70A, and is an annular member that is disposed substantially coaxially with the first motor cover cylindrical portion724A.

The motor cover70A includes a plurality of stator blades73A disposed on an outer surface721A of the motor cover cylindrical portion in the circumferential direction. The plurality of stator blades73A are formed on an outer surface of the first motor cover cylindrical portion724A. The first motor cover cylindrical portion724A, the plurality of stator blades73A, and a blower cover74A are an integral resin member. Since the first motor cover cylindrical portion724A includes the motor cover top plate portion71A, the rigidity thereof is higher than that of the second motor cover cylindrical portion725A. Accordingly, by being configured as a portion integral with the first motor cover cylindrical portion724A, the plurality of stator blades73A can, compared with being configured in the second motor cover cylindrical portion725A, improve the fixing strength. In other words, by forming the stator blades73A on the outer surface of the first motor cover cylindrical portion724A, vibrations of the stator blades73A can be reduced when the air is flowing inside a flow passage80A.

The motor cover cylindrical portion72A includes cylindrical portion upper wall portions77A that connect the outer surface721A of the motor cover cylindrical portion and an inner surface722A of the motor cover cylindrical portion to each other, and that constitute upper side walls of the communication portions75A in the axial direction. In the present embodiment, the cylindrical portion upper wall portions77A are constituted by portions of the underside of the first motor cover cylindrical portion724A. Radial-direction outer end portions of the cylindrical portion upper wall portions77A are disposed below radial-direction inner end portions of the cylindrical portion upper wall portions77A in the axial direction. With the above, the air discharged from the inner space83A of the motor cover cylindrical portion to the outer space82A of the motor cover cylindrical portion through the communication portions75A includes a velocity component oriented downwards in the axial direction. Accordingly, since the air flowing in the flow passage through the communication portions75A can smoothly merge with the air flowing downwards inside the flow passage80A, the air blowing efficiency inside the flow passage80A is improved.

Furthermore, in the present embodiment, the cylindrical portion upper wall portions77A are smooth curved surfaces that connect the radial-direction outer end portions of the cylindrical portion upper wall portions77A and the radial-direction inner end portions of the cylindrical portion upper wall portions77A to each other and that protrude towards the upper side in the axial direction. With the above, since the air that passes through the communication portions75A and that is discharged to the outer space82A of the motor cover cylindrical portion is guided in a smooth manner along the cylindrical portion upper wall portions77A towards the outer side in the radial direction and towards the lower side in the axial direction, the air can be merged in a more efficient manner with the air flowing downwards inside the flow passage80A; accordingly, the air blowing efficiency inside the flow passage80A is improved.

The radial-direction outer end portions of the cylindrical portion upper wall portions77A are disposed above lower ends of the stator blades73A in the axial direction. With the above, the communication portions75A can be disposed on the upper side in the axial direction to the extent possible. When a portion of the air that has been discharged towards the outer side in the radial direction with the rotation of an impeller50A, that has passed through the flow passage80A, and that has been discharged downwards from an exhaust port81A circulates the inner space83A of the motor cover cylindrical portion, passes through the communication portions75A, and merges again in the flow passage80A, by disposing, to the extent possible, the communication portions75A on the upper side in the axial direction, the distance in which the circulating air passes the inner space83A of the motor cover cylindrical portion can be made longer; accordingly, the heat generated in the inner space83A of the motor cover cylindrical portion can be discharged more efficiently to the outer space82A of the motor cover cylindrical portion.

Particularly, in the present embodiment, since a circuit board36A is disposed on the upper side of the inner space83A of the motor cover cylindrical portion, by having the air that circulates in the inner space83A of the motor cover cylindrical portion reach, to the extent possible, the upper side in the axial direction and flow to the outer space82A of the motor cover cylindrical portion, the heat generated from the circuit element disposed on the circuit board36A can be efficiently discharged.

Furthermore, in the present embodiment, the communication portions75A are not cutaways that are open downwards but are through holes constituted by the first motor cover cylindrical portion724A and the second motor cover cylindrical portion725A. Accordingly, compared with a case in which the communication portions75are formed to the upper portion of the inner space83of the motor cover cylindrical portion with recesses that are greatly recessed upwards in the axial direction, the rigidity of the motor cover cylindrical portion72A can be improved; accordingly, vibration of the motor cover cylindrical portion72A caused by the air flowing inside the flow passage80A can be reduced.

The motor cover cylindrical portion72A includes cylindrical portion lower wall portions78A that connect the outer surface721A of the motor cover cylindrical portion and an inner surface722A of the motor cover cylindrical portion to each other, and that constitute lower side walls of the communication portions75A in the axial direction. In the present embodiment, the cylindrical portion lower wall portions78A are constituted by portions of the upper surface of the second motor cover cylindrical portion725A. Radial-direction outer end portions of the cylindrical portion lower wall portions78A are disposed below radial-direction inner end portions of the cylindrical portion lower wall portions78A in the axial direction. With the above, the air discharged from the inner space83A of the motor cover cylindrical portion to the outer space82A of the motor cover cylindrical portion through the communication portions75A includes a velocity component oriented downwards in the axial direction. Accordingly, since the air flowing in the flow passage80A through the communication portions75A can smoothly merge with the air flowing downwards inside the flow passage, the air blowing efficiency inside the flow passage80A is improved.

The motor cover cylindrical portion72A includes cylindrical portion side wall portions76A that connect the outer surface721A of the motor cover cylindrical portion and the inner surface722A of the motor cover cylindrical portion to each other. The cylindrical portion side wall portions76A connect radial-direction outer end portions761A of the cylindrical portion side wall portions and radial-direction inner end portions762A of the cylindrical portion side wall portions to each other. The cylindrical portion side wall portions76A are side walls of the communication portions75A. The motor cover cylindrical portion72A includes other cylindrical portion side wall portions76A that oppose the cylindrical portion side wall portions76A described above with a gap in between in the circumferential direction. The other cylindrical portion side wall portions76A are side walls of the communication portions75A. In other words, the motor cover cylindrical portion72A includes cylindrical portion side wall portions76A that connect the outer surface721A of the motor cover cylindrical portion and the inner surface722A of the motor cover cylindrical portion to each other and that constitute the side walls of the communication portions75A. The width of each communication portion75A in the circumferential direction is the same as a width in the circumferential direction between two cylindrical portion side wall portions76A that oppose each other with a gap in between in the circumferential direction. In the present embodiment, the cylindrical portion side wall portions76A are constituted by portions of the second motor cover cylindrical portion725A. However, the cylindrical portion side wall portions76A may be constituted by portions of the first motor cover cylindrical portion724A.

The radial-direction outer end portions761A of the cylindrical portion side wall portions are disposed on the front side in the rotation direction R of the impeller with respect to the radial-direction inner end portions762A of the cylindrical portion side wall portions. Describing in more detail, the cylindrical portion side wall portions76A are smooth curved surfaces that protrude towards the rear side in the rotation direction R of the impeller and connect the radial-direction outer end portions761A of the cylindrical portion side wall portions and the radial-direction inner end portions762A of the cylindrical portion side wall portions to each other. With the above, since merging with the air flowing in the flow passage80A can be performed in a further smooth manner, the air blowing efficiency inside the flow passage80A is improved. The mechanism in which the air blowing efficiency improves is similar to the mechanism in the cylindrical portion side wall portions76of the first embodiment. As illustrated inFIG. 6, the rotation direction R of the impeller is clockwise when viewed from the lower side in the axial direction.

Note that the communication portions75A that penetrate in the radial direction may be formed of through holes that penetrate the motor cover cylindrical portion72A, which is an integral member, in the radial direction. As in the present embodiment, in a case in which the motor cover cylindrical portion72A is constituted by the first motor cover cylindrical portion724A and the second motor cover cylindrical portion725A, the first motor cover cylindrical portion724A and the second motor cover cylindrical portion725A can each be formed by molds that slide in the up-down direction; accordingly, mass-productiveness is improved when forming the communication portions75A that penetrate the motor cover cylindrical portion72A in the radial direction, which is a more desirable configuration.

The communication portions75A are, desirably, configured in plural numbers in the circumferential direction. With the above, the heat generated in the inner space83A of the motor cover cylindrical portion can be discharged to the outer space82A of the motor cover cylindrical portion in a more effective manner. Furthermore, in the present embodiment, while a motor10A is a so-called outer rotor type, the motor10A may be an inner rotor type. In a case in which an inner rotor type motor is disposed, the air that circulates the inner space83A of the motor cover cylindrical portion flows on the outer side of the motor cover that covers the outer side of the motor10A.

Accordingly, the heat that has been generated in the coils and the like and that has been transmitted to the motor cover through the stator can be discharged to the outer space82A of the motor cover cylindrical portion.

FIG. 7is a perspective view of a vacuum cleaner100. The vacuum cleaner100includes the blowing device of the present disclosure. With the above, in the blowing device mounted in the vacuum cleaner100, the heat generated in the inner space of the motor cover cylindrical portion can be discharged to the outer space of the motor cover cylindrical portion in an efficient manner. Accordingly, a vacuum cleaner100with a superior cooling function can be obtained.

While the exemplary embodiments of the present disclosure have been described above, the configuration of and the combination in each of the first embodiment and the second embodiment are examples, and adding of configurations, discarding thereof, replacing and other modifications can be made within the scope of the present disclosure. Furthermore, the present disclosure is not to be limited by the embodiments. Furthermore, the blowing device of the present disclosure can be used in electrical machineries other than the vacuum cleaner.