JPH11344000A - Electric blower - Google Patents

Abstract

(57) [Problem] An object of the present invention is to provide an electric blower that can be reduced in size and improved in performance by enhancing the cooling effect of the electric motor. SOLUTION: In a frame 111 composed of a main frame 120 and a sub-frame 130, a stator core 141 whose axial projection outer shape of the main frame 120 is formed in a substantially rectangular shape is housed. Outer side 143
The annular wall 121 of the main frame 120 on the side opposite to the opening 122 is swelled along the axial direction from the opening 122 side to increase the cross-sectional area of the air passage 128 along the axial direction. A small-sized and high-performance electric blower that is formed at least halfway in the axial direction of the outer peripheral surface 143 of the stator core 141 to increase the flow rate of cooling air per unit time and enhance the cooling effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric blower used for a vacuum cleaner or the like.

[0002]

2. Description of the Related Art An electric blower comprising an electric motor and a blower fan is used for various devices such as a vacuum cleaner.

[0003] In a device such as a vacuum cleaner,
According to the market requirements, there is a demand for a compact and high-performance one, that is, one with a large dust-absorbing power. In order to reduce the size and performance of these devices, it is necessary to reduce the size and performance of the electric blower. As one of the elements for miniaturization and high performance of this electric blower,
It is necessary to reduce the size and performance of the motor, that is, to increase the output.

[0004] However, miniaturization and high output of the motor are contradictory. In other words, in order to increase the output of the motor, it is necessary to increase the outer shape of the stator due to the relationship with the stator windings, etc. When the outer shape of the stator is increased, the outer shape of the frame that houses the stator is increased. Since the size must be increased, the size cannot be reduced.

On the other hand, if the size of the motor is reduced while the output of the motor is increased, the amount of heat generated by the motor also increases, so that it is necessary to sufficiently cool the motor. For this reason, conventionally, in order to make this cooling as effective as possible, the air flow sucked from the blower fan is formed into a space formed inside the frame of the electric motor, that is, between the inner peripheral wall surface of the frame and the outer surface of the stator. In some cases, an air path is formed in the air path, and the air flow, that is, cooling air is passed through the air path to cool the air path.

[0006] Here, referring to Figs. 6 and 7, an electric blower in which an air path is formed inside the frame of the electric motor as described above, and cooling air is passed through the air path to cool the air path will be described. explain. 6 is a cross-sectional view of one side from the center of the electric blower, and FIG. 7 is a view as seen from the direction of the line YY in FIG. In FIG. 7, the rotor is omitted.

As shown in FIG. 6, the electric blower 100 is
It is constituted by an electric motor 110 and a blower fan 160.

The electric motor 110 is connected to the main frame 12
The main frame 120 includes a stator 111, a rotor 150, and the like.

As shown in FIG. 6, the main frame 120 is made of an iron plate and has an annular wall 121, a bottom wall 123 at one end of the annular wall 121, and an opening 122 at the other end. Is formed. An outlet 124 is formed on the bottom wall 123 side of the annular wall 121. Also,
As shown in FIG. 6, a through hole 125 is formed on the bottom wall 123 side of the annular wall 121, and a brush holder 170 is attached to the through hole 125 with a screw 174. 1
73, a commutator piece 154a of a commutator 154 described later.
And the brush 171 is housed.

In the bottom wall 123, a bearing recess 126 is provided.
A ball bearing 176 as a bearing is press-fitted in the bearing recess 126.

The opening 122 of the main frame 120
A circular flange portion 127 is formed on the periphery of.

Next, the sub-frame 130 is made of an iron plate and formed in a strip shape, and as shown in FIG.
The ball bearing 177 as a bearing is press-fitted in the bearing recess 131. In addition, a through hole 132 is formed in the bottom wall of the bearing recess 131 to allow a rotating shaft to be described later to pass therethrough. The sub-frame 130 has an opening 122 of the main frame 120 whose longitudinal direction is a direction orthogonal to the paper surface in FIG.
To the flange portion 1 with screws (not shown).
27.

Next, the stator 140 is formed by punching a magnetic steel plate to form a substantially square outer shape as shown in FIG. 7, and laminating a core (not shown) having a pair of magnetic poles facing each other. The stator core 141 includes a stator winding 144 wound around a magnetic pole (not shown) of the stator core 141.

Each of the corners 14 of the stator core 141
5 is formed to have an outer shape larger by an amount of press-fitting into the annular wall 121 of the main frame 120, and the stator core 141 is formed by press-fitting the corners 145 into the annular wall 121 of the main frame 120. It is housed in the frame 120.

The stator 140 is connected to the main frame 120.
6 and 7, the inner wall surface of the main frame 120, which is formed in an arc shape, that is, the inner peripheral surface 121a of the annular wall 121 and the stator core 141, respectively, as shown in FIGS. An air passage 128 is formed by a space surrounded by the straight outer surface 143 and along the axial direction of the main frame 120, and the air passage 128 communicates with the outlet 124.

Next, the rotor 150 has a rotor core 151 formed by laminating cores formed by punching magnetic steel plates, and a rotor 150 press-fitted into a shaft hole 152 formed in the center of the rotor core 151. A shaft 155, a large number of commutator pieces 154a attached to the rotating shaft 155, and an insulator 154;
b, and a rotor winding 153 wound around the rotor core 151.

A screw 156 is formed at one end of the rotating shaft 155. And the rotor 150
Press-fits the end of the rotating shaft 155 on the side where the commutator 154 is attached to the inner race of the ball bearing 176, and closes the end on the side where the screw 156 is provided to the sub-frame 130. It is press-fitted into the inner ring of the mounted ball bearing 177 and is rotatably disposed in the frame 111. When the rotor 150 is disposed in the frame 111, the portion of the rotary shaft 155 where the screw 156 is provided protrudes outward from the sub-frame 130.

The blower fan 160 includes a rotating fan 161, a rectifying plate 165 disposed downstream of the rotating fan 161, that is, a sub-frame 130 in FIG. 6, and a fan that covers the rectifying plate 165 and the rotating fan 161. And a cover 167.

The rotating fan 161 is composed of a main plate 162 and a sub plate 163, and a plurality of blades 164 arranged between the main plate 162 and the sub plate 163. The main plate 1
A fitting hole 1 for fitting to the rotation shaft 155
62a are formed. A suction opening 163a is formed at the center of the sub-plate 163. When the rotating fan 161 is rotated by the electric motor 110, air is sucked from the suction opening 163a, and the air is discharged from the outer periphery of the rotating fan 161. It has become so.

Although not shown, the flow regulating plate 165 is provided with a guide flow path through which an air flow discharged from the outer peripheral portion of the rotary fan 161 flows out to the opening 122 side of the main frame 120. The fitting hole 165 that fits into the outer periphery of the bearing recess 131 of the sub-frame 130 is provided in the portion.
a is formed.

The current plate 165 is connected to the fitting hole 1.
65 a is fitted to the outer periphery of the bearing recess 131, and is attached to the sub-frame 130 by screws 166.

As shown in FIG. 6, the fan cover 167 is formed in a bottomed cylindrical shape having an opening 168 on the main frame 120 side, and is formed on a sub-plate 163 of the rotary fan 161 at the bottom thereof. An opening 167a formed corresponding to the suction opening 163a is provided. Also,
The inner peripheral surface of the opening edge of the opening 168 of the fan cover 167 is the fitting edge 1 of the flange portion 127 of the main frame 120.
27a.

The blower fan 160 constructed as described above is attached to the electric motor 110 as follows.

First, as described above, the current plate 165 is fitted to the outer periphery of the bearing recess 131 of the sub-frame 130 by fitting the fitting hole 165 a to the sub-frame 130 with the screw 166.

Next, the main plate 1 of the rotating fan 161
The fitting hole 162a provided on the rotating shaft 155 is fitted to the rotating shaft 155, and then the nut 169 is fastened to the screw 156 of the rotating shaft 155, thereby rotating the rotating fan 161 to the rotating shaft 155.
Attach to

Next, the fan 160 is attached to the electric motor 110 by fitting the fan cover 167 to the fitting edge 127a of the main frame 120 so as to cover the rotating fan 161 and the current plate 165. Assembled as blower 100.

Then, the electric motor 110 of the electric blower 100
Is driven, the rotating fan 161 rotates, and this rotation causes external air to flow through the opening 167 of the fan cover 167.
a, suction opening 1 of sub-plate 163 of rotating fan 161
63a, and then discharged from the outer peripheral portion of the rotary fan 161.
The main frame 12 is guided by a guide passage 65 (not shown).
It is guided to the opening 122 of the main frame 120 and flows into the main frame 120.

Next, the air flow that has flowed into the opening 122 is exhausted to the outside from the outlet 124 through the air passage 128. When the air flow passes through the air passage 128, the electric motor 110 is cooled by the air flow.

As described above, the electric motor 110 is
Since the air that has flowed in through the air passage 60 is cooled by passing through the air passage 128 formed in the electric motor 110 as the cooling air, the effective cooling of the electric motor 110 is performed in the unit time of the cooling air flowing through the air passage 128. This is done by increasing the flow per hit. In other words, in order to effectively cool the electric motor 110, it is necessary to increase the cross-sectional area of the air passage 128.

By the way, in order to reduce the size and increase the output of the electric motor 110, as described above,
It is necessary to increase the outer diameter of the stator core 141 without increasing the diameter of the annular wall 121. If the outer diameter of the stator core 141 is increased without increasing the diameter of the annular wall 121 of the main frame 120 as described above, the flow path cross-sectional area of the air passage 128 is reduced, and cooling flowing through the air passage 128 is reduced. There is a possibility that the flow rate of the wind is reduced and sufficient cooling cannot be performed, which causes deterioration of an insulator used in the motor 110, affects the durability of the motor 110, and in some cases causes burning of the motor 110. There is.

[0031]

As described above, the electric blower used in a device such as a vacuum cleaner is required to be small in size and high in performance. And high output is required. Then, without increasing the outer shape or diameter of the main frame in order to reduce the size of the electric motor, and by increasing the outer shape of the stator core in order to achieve high output, the cooling formed in the main frame as described above. Since the cross-sectional area of the air passage through which the air flows cannot be made large, the motor cannot be sufficiently cooled, and as a result, there is a problem that the size and the output cannot be increased.

[0032]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and the invention according to claim 1 is a bottomed cylindrical shape having an opening at one end of an annular wall and a bottom wall at the other end. A frame formed of a main frame having an outlet on the bottom wall side and a sub-frame provided in the opening of the main frame, having a magnetic pole opposed to each other, and projecting an axial projection outline of the annular wall. A stator core formed in a substantially square shape and a stator winding wound around the stator core are formed by press-fitting the outer periphery of a corner portion of the stator core into the inner peripheral wall of the annular wall, thereby forming the stator core inside the main frame. And a motor having a rotor supported by a bearing provided on the bottom wall and the sub-frame of the main frame and a sub-frame and having a rotor disposed between the magnetic poles of the stator; and Attached to one end of the rotating shaft provided on the opening side A rotating fan, a rectifying plate disposed downstream of the rotating fan, a blower fan comprising a fan cover attached to the frame while covering the rotating fan and the rectifying plate having a suction port, The air flow sucked from the suction port of the fan cover by the rotation of the electric motor is formed by an inner circumferential wall surface of the main frame and a space along the axial direction of the main frame by each outer surface of the substantially square stator core. In the electric blower that flows out of the outlet through an air passage, the annular wall of the main frame facing the outer side surface of the stator core is axially bulged outward from the opening side to extend in the axial direction. An electric transmission having a bulging portion for increasing the cross-sectional area of the air passage along the air passage and forming the bulging portion from the opening at least halfway in the axial direction of the outer surface. It is obtained by a machine.

As described above, according to the first aspect of the invention, the axially projected outer shape of the main frame is formed into a substantially rectangular shape in the frame including the main frame and the sub-frame provided in the opening of the main frame. And an annular wall of the main frame facing the outer side surface of the stator core is axially extended from the opening side and bulges outward, and the air path of the air path along the axial direction is accommodated. Since the bulging portion for increasing the cross-sectional area is formed from the opening to at least halfway in the axial direction of the outer peripheral surface of the stator core, the amount of cooling air flowing in the air passage can be increased, and the electric motor can be increased. This has the effect of increasing the cooling effect of
Therefore, the size of the electric motor, that is, the electric blower can be reduced and the performance thereof can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the bulging portion formed on the annular wall of the main frame extends from the opening of the main frame to the stator core at the bottom wall side of the main frame. This is an electric blower formed up to a position beyond the end face.

According to the second aspect of the present invention, in the first aspect of the present invention, the bulge formed on the annular wall of the main frame extends from the opening of the main frame to the stator core on the bottom wall side of the main frame. Since it was formed to a position beyond the end face of
In addition to the effect of the first aspect of the present invention, since the amount of cooling air flowing in the air passage can be increased, the cooling effect of the electric motor can be further enhanced.

According to a third aspect of the present invention, there is provided the electric blower according to the first or second aspect of the present invention, wherein a circumferential boundary between the bulging portion and the annular wall has a smooth curved surface. .

According to the third aspect of the present invention, the boundary between the bulging portion and the annular wall in the circumferential direction is a smooth curved surface in the first or second aspect of the invention. Alternatively, in addition to the effect of the second aspect of the present invention, there is an effect that the flow of the cooling air into the air path can be made smooth and the generation of noise due to the flow of the cooling air can be suppressed.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the shape of the cross section of the air passage along the axial direction is more downstream than the upstream in the rotation direction of the rotor. Is an enlarged electric blower.

As described above, according to the fourth aspect of the present invention, in the first to third aspects of the present invention, the shape of the cross section of the air path along the axial direction is more downstream than the upstream side in the rotational direction of the rotor. Since the large side is formed, in addition to the effects of the inventions according to the first to third aspects, the flow of the cooling air into the air passage can be made smoother, and the generation of noise due to the flow of the cooling air can be generated. Can be further suppressed.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the same components as those of the conventional electric blower described above are denoted by the same reference numerals, and
The description is omitted. Further, in the description, the reference numerals used for the conventional electric blower will be used.

As shown in FIG. 1, the portion of the annular wall 121 of the main frame 120 of the electric blower 100A facing each outer side surface 143 of the stator core 141 is substantially axially projected as shown in FIG. Groove-shaped recess 22 along the axial direction in the shape of a letter
Bulging portion 22 bulging outward to form 1
2 are formed. As shown in FIG. 1, the bulging portion 222 is formed at an intermediate portion in the axial direction of the outer peripheral surface of the stator core 141, that is, halfway.

The groove-shaped recess 221 formed by the bulging portion 222 communicates with the opening 122, whereby the inner peripheral surface of the annular wall 121 facing each outer surface 143 of the stator core 141. The flow path cross-sectional area of the air passage 128 formed by being surrounded by 121 a
2 is formed larger by the cross-sectional area of the groove-shaped recess 222.

Therefore, the flow rate of the cooling air flowing through the air passage 128 per unit time increases, and the electric motor 110
The cooling effect can be enhanced.

Further, the bulging portion 222 is
0 is formed so as to be located inside the outer peripheral edge of the flange portion 127 to which the bulge portion 2 is attached.
Even if 22 is formed, the outer shape in the outer peripheral direction of the electric blower 100A does not increase. Further, since the bulging portion 222 is formed by using a portion serving as a dead space portion formed on the side of the electric motor 110 of the blower fan 160 when the electric blower 100A is incorporated into a device such as a vacuum cleaner, It is not necessary to increase the space for incorporation even in the case of incorporation into the device.

The groove-shaped recess 222 is formed in the opening 122.
From the center of the outer surface of the stator core 141 in the axial direction, that is, at the upstream side of the air passage,
The portion of the air passage having a large cross-sectional area is only on the upstream side of the air passage.
22, the opening area of the air passage 128 is large. Therefore, the air flow flowing from the blower fan 160 flows smoothly into the air passage 128, and the air flow once flowing, that is, the cooling air is Since the cooling air is forcibly pushed toward the downstream side of 128, the flow rate of the cooling air per unit time increases, and therefore, the cooling effect of the electric motor can be enhanced as described above.

The operation of the electric blower 100A is the same as that of the above-described conventional case, and a description thereof will be omitted.

As described above, the main frame 120 and the sub-frame 130 provided in the opening 122 of the main frame 120 are contained in the main frame 120.
Stator 1 whose projected outline in the axial direction of 0 is formed in a substantially square shape
While press-fitting and storing the stator core 141 of the 40,
The annular wall 121 of the main frame 120 facing each outer peripheral surface 143 of the stator core 141 extends along the axial direction from the opening 122 side, and bulges outward. The bulging portion 222 for increasing the road cross-sectional area is formed at least on the outer peripheral surface 1 of the stator
43 is formed halfway in the axial direction,
Since the amount of the cooling air flowing in the inside 8, that is, the flow rate per unit time can be increased, the cooling effect of the electric motor 110 can be enhanced. Therefore, the motor 110
That is, the size and the performance of the electric blower 100A can be reduced.

In the above embodiment, the bulging portion 222 forming the groove-like concave portion 222 is not
1 is formed halfway of the outer side surface 143 to increase the cross section of the flow passage only on the upstream side of the air passage 128. However, as shown in FIG. The distance L2 from the end face to the end face on the terminal end of the bulging portion 222 is formed larger than the distance L1 from the end face to the end face of the stator core 141 on the bottom wall 123 side of the main frame 120,
That is, the bulging portion 222 is formed to a position beyond the end surface of the stator core 141 on the bottom wall 123 side of the main frame 120,
The flow path cross-sectional area may be increased over the entire length of the air passage 128 in the axial direction. Since the flow rate of the cooling air flowing through the passage 128 per unit time can be increased, the cooling effect of the electric motor 110 can be further enhanced.

In the above-described embodiment, the axial projection formed by forming the bulging portion 222 on the annular wall 121 of the main frame 120 is used to convert the substantially U-shaped groove-shaped concave portion 2.
The boundary between the two sides of the inner wall 21 and the inner peripheral surface 121a of the annular wall 121, that is, the corner 223 is formed at an acute angle as shown in FIG. 2, but is formed into a smooth curved surface 223a as shown in FIG. In this way, the boundary 223 has a smooth curved surface.
In the case of “a”, the rotation direction of the rotation fan 161 from the blower fan 160 into the air passage 128 (the direction indicated by the arrow in FIG. 4)
The air flow flowing along the air flows smoothly, and the generation of turbulence such as vortex generated at each boundary portion can be suppressed. Therefore, the generation of noise due to the turbulence can be suppressed.

Similarly, by forming the corner 224 inside the groove-shaped recess 221 as a smooth curved surface 224a without forming an acute angle, the flow of the air flow at this corner can be made smooth.

In the above embodiment, the projection in the axial direction formed by forming the bulging portion 222 on the annular wall 121 of the main frame 120 is used to convert the substantially U-shaped groove-shaped concave portion 2.
As shown in FIG. 2, the center of 21 is formed so as to coincide with the lines A and B passing through the center O of the main frame 120, and the areas on both sides of the lines A and B are made equal.
As shown in FIG. 5, the area on both sides of the line A and the line B passing through the center O of the main frame 120 is determined by the rotation direction of the rotor 150, that is, the direction in which the air flow generated by the rotation of the rotary fan 161 flows (FIG. The area S2 on the downstream side of the area S1 on the upstream side (the direction indicated by the arrow)
(A region with a line) may be formed to be large, and thus an area S1 on the downstream side with respect to the area S1 on the upstream side is thus obtained.
2 is formed large, the flow of the cooling air is increased because the flow of air flowing while rotating in the circumferential direction increases the flow path cross section of the portion where the air density on the downstream side in the circumferential direction of the groove-shaped recess 221 becomes dense. It can be smooth.

Also in this case, as shown in FIG. 5, by forming each boundary portion and the inner corner portion of the groove-shaped concave portion 221 into a smooth curved surface, as in the case shown in FIG.
Since the occurrence of turbulence such as a vortex generated at each boundary portion and corner portion can be suppressed, the generation of noise due to the turbulence can be suppressed.

Further, in the above embodiment, the electric motor has a configuration in which the stator and the rotor use the iron core in which the cores are laminated, but this may be a configuration in which either one uses a permanent magnet. .

In the above embodiment, the centrifugal fan is used as the rotating fan of the blower fan.
This may be a blower fan using another type of rotating fan.

[0056]

As described above, according to the first aspect of the present invention, the axially projected outer shape of the main frame is set in a frame composed of the main frame and the sub-frame provided in the opening of the main frame. A wind path along the axial direction, which accommodates the stator core formed in the shape and expands the annular wall of the main frame facing the outer side surface of the stator core outward from the opening side along the axial direction. Since the bulging portion that increases the cross-sectional area of the air passage is formed from the opening to at least halfway in the axial direction of the outer surface of the stator core, the amount of cooling air flowing through the air passage can be increased, This has the effect of increasing the cooling effect of the electric motor and, therefore, achieving downsizing and higher performance of the electric motor, that is, the electric blower.

According to a second aspect of the present invention, in the first aspect of the present invention, the bulge formed in the annular wall of the main frame extends from the opening of the main frame to the stator core at the bottom wall side of the main frame. In addition to the effects of the first aspect of the present invention, since the cooling air is formed to a position beyond the end face, the amount of cooling air flowing in the air path can be increased, so that the cooling effect of the electric motor can be further improved. It has.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the boundary between the bulging portion and the annular wall in the circumferential direction is a smooth curved surface.
Alternatively, in addition to the effect of the second aspect of the present invention, there is an effect that the flow of the cooling air into the air path can be made smooth and the generation of noise due to the flow of the cooling air can be suppressed.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the shape of the cross section of the air passage along the axial direction is more downstream than the upstream in the rotation direction of the rotor. Is increased, in addition to the effects of the first to third aspects of the present invention, the flow of the cooling air into the air path can be made smoother, and the generation of noise due to the flow of the cooling air can be further reduced. It has the effect that it can be suppressed.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a part of an electric blower according to an embodiment of the present invention.

FIG. 2 is a plan view of the electric blower viewed from the axial direction of the electric motor (a plan view taken along line XX of FIG. 1).

FIG. 3 is a partially sectional side view showing another embodiment of the bulging portion of the electric blower.

FIG. 4 is a diagram showing another embodiment of the air path of the electric blower.

FIG. 5 is a diagram showing another embodiment of the air path of the electric blower.

FIG. 6 is a side view in which a part of a conventional electric blower is sectioned.

FIG. 7 is a plan view of the electric motor of the conventional electric blower as viewed from the axial direction (a plan view taken along line YY in FIG. 6).

[Explanation of symbols]

 REFERENCE SIGNS LIST 100A electric blower 110 electric motor 111 frame 120 main frame 121 annular wall 122 opening of main frame 123 bottom wall of main frame 124 outlet 128 air passage 130 sub-frame 140 stator 141 stator core 143 linear outer surface of stator core 144 Stator winding 150 Rotor 151 Rotor core 155 Rotating shaft 160 Sending fan 176 Ball bearing (bearing) 177 Ball bearing (bearing) 222 Swelling part

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H02K 5/20 H02K 5/20 9/06 9/06 C

Claims (4)

[Claims] 1. A main frame which is formed in a bottomed cylindrical shape having an opening at one end of an annular wall and a bottom wall at the other end, and having an outlet at a bottom wall side, and provided at the opening of the main frame. A stator core having a magnetic pole facing each other, a stator core having an annular projected shape in the axial direction of the annular wall formed in a substantially rectangular shape, and a stator winding wound around the stator core. The stator shaft housed in the main frame by press-fitting the outer periphery of the corner portion of the stator core into the inner peripheral wall of the annular wall, and a rotating shaft provided on a bearing provided on the bottom wall and the sub-frame of the main frame. An electric motor supported by a rotor disposed between the magnetic poles of the stator, a rotating fan provided at the opening side of the main frame and attached to one end of the rotating shaft, and disposed downstream of the rotating fan; With rectifying fan and suction port installed And a fan cover that covers the rotary fan and the rectifying plate and that is attached to the frame. The air flow sucked from the suction port of the fan cover by the rotation of the electric motor causes the air flow to pass through the inner periphery of the main frame. In an electric blower which flows out of the outlet through a wind path formed by a space along the axial direction of a main frame by a wall surface and each outer surface of the substantially rectangular stator core, the stator faces the outer surface of the stator core. Along with the annular wall of the main frame extending in the axial direction from the opening side and bulging outward to form a bulging portion for increasing the cross-sectional area of the airflow along the axial direction, the bulging portion is formed. An electric blower, wherein the blower is formed at least halfway in the axial direction of the outer surface from the opening. 2. The invention according to claim 1, wherein the bulge formed in the annular wall of the main frame extends from an opening of the main frame to a position beyond an end surface of the stator core on the bottom wall side of the main frame. The electric blower characterized by the above. 3. The electric blower according to claim 1, wherein a circumferential boundary between the bulging portion and the annular wall has a smooth curved surface. 4. The invention according to claim 1, wherein the shape of the cross section of the air passage along the axial direction is larger on the downstream side than on the upstream side in the rotation direction of the rotor. Electric blower.