JP2778266B2 - Electric blower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric blower used for a vacuum cleaner.

[0002]

2. Description of the Related Art In recent years, in the vacuum cleaner industry, there has been a trend toward smaller size and higher output, and impellers have been required to be smaller and have higher performance than before.

[0003] A conventional electric blower will be described below. In FIG. 6, an impeller 1 is directly connected to a motor shaft 5 of a motor 4 on an air guide 3 installed on an upper portion of a motor frame 2, and a casing 6 has an intake port 10 at the center and includes the impeller 1. Is attached to the motor frame 2. The impeller 1 includes a blade 7, a front shroud 8, and a rear shroud 9.

The operation of the electric blower configured as described above will be described below. By rotating the impeller 1 attached to the motor 4 at a high speed, the air introduced from the intake port 10 passes between the blades 7 of the impeller 1 and the air passage formed by the front and rear shrouds 8, 9, so that the air volume and the vacuum are reduced. Pressure can be obtained. The air that has flowed out of the impeller 1 passes through the air guide 3, is converted from static pressure into dynamic pressure, passes while cooling the inside of the motor 4, and is exhausted outside the motor 4.

[0005]

However, in the conventional configuration, the impeller 1 rotates at a high speed exceeding 30,000 rpm, so that the front and rear shrouds 8, 9 and the blades 7 are rotated.
The air passage formed between them is in a turbulent state, and the effective passage cross-sectional area in which air actually flows becomes narrower as the turbulent boundary layer develops. In particular, in the case of the impeller 1 used for the electric blower, the existence of the turbulent boundary layer becomes important because the original passage cross-sectional area is small.

Further, as one of means for improving the efficiency of the impeller, the front shroud 8 has a substantially conical shape. However, there is a method in which a part of the front shroud 8 is set lower than the outlet height to be concave. is there. This is to increase the flow rate by narrowing the air passage and increase the efficiency by reducing the swirl region. From this experiment, this front shroud 8
As the amount of narrowing down increases (the distance between the front shroud and the rear shroud becomes smaller), the efficiency also tends to increase.

However, the turbulent boundary layer generated in the front shroud 8 and the rear shroud 9
The effective air passage sandwiched between the turbulent boundary layers generated in the air becomes narrow, and as a result, the air does not flow.

As described above, conventionally, the air flow near the turbulent boundary layer generated on the inner wall surfaces of the blade 7 and the front and rear shrouds 8 and 9 constituting the air passage of the impeller 1 is improved to improve the turbulent boundary layer. The challenge is to reduce the thickness and increase the effective air passage cross-sectional area.

Conventionally, a gap of about 3 to 4 mm is provided between the impeller 1 and the casing 6 so as not to hinder the rotation of the impeller due to the influence of the turbulent boundary layer thickness generated on the mutual wall surface. Since the vicinity of the intake port 10 is at a negative pressure, a part of the exhaust flow (positive pressure) exiting from the impeller 1 passes through the gap between the casing 6 and the impeller 1 and flows into the intake port 10 of the impeller, so that the efficiency is increased by the so-called secondary flow. Is causing a decline.

Accordingly, a first object of the present invention is to provide a high-efficiency, low-noise electric blower which suppresses eddy currents by rectifying turbulent flows and increases the air volume accompanying an increase in the effective air passage cross-sectional area.

A second object of the present invention is to increase the efficiency of the electric blower by suppressing a secondary flow occurring between the impeller and the casing.

[0012]

In order to achieve the first object, an electric blower according to the present invention has a groove on a surface of a blade in a direction substantially the same as the flow of air from an inlet side end to an outlet side end. And a groove is provided on the inner wall surfaces of the front and rear shrouds in substantially the same direction as the air flow.

In order to achieve the second object, the electric blower according to the present invention is provided with grooves on the outer wall surface of the front shroud and the inner wall surface of the casing, respectively, concentrically with the motor shaft.

[0014]

According to the above construction, the turbulent flow and the vortex flow are rectified by the grooves in the substantially same direction as the air flow, the effective passage cross-sectional area is enlarged by reducing the turbulent boundary layer, and the efficiency and the efficiency of the electric blower are improved. Noise can be reduced.

The turbulent boundary layer generated on both wall surfaces can be made thinner by the concentric grooves provided on the outer wall surface of the front shroud and the inner wall surface of the casing. Can be reduced. Furthermore, since this groove is arranged concentrically with the motor shaft, the air in the gap surrounded by the outer wall of the front shroud and the inner wall of the casing also forms a flow along the groove, so that the leakage due to the secondary flow of the impeller Loss can be suppressed.

[0016]

Embodiment (Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 3, reference numeral 21 denotes a centrifugal impeller having a plurality of blades 22 and a front shroud 27 and a rear shroud 28 sandwiching the blades 22.
2, an air guide 23 is provided.
The casing 24 includes the impeller 22 and the air guide 23 and is attached to a motor frame of a motor 29. The diffuser 25 formed by the casing 24 and the air guide 23 is disposed so as to have a passage that expands toward the outer periphery, and a return passage 26 is formed so as to smoothly and independently communicate with the end of the diffuser 25. The airflow flowing from the return passage 26 is discharged from the exhaust hole 30 while cooling the inside of the motor 29.

Next, the surface of the blade 22 is
A fine groove 31 having a V-shaped cross section is provided in the same direction as the flow of air from the four side end to the opposite outlet side end. Similarly, fine grooves 32 and 33 having a V-shaped cross section are arranged on the inner wall surfaces of the front shroud 27 and the rear shroud 28 in substantially the same direction as the flow of air. 34 is a casing 24
Is an air passage surrounded by the front shroud 27, the rear shroud 28, and the blade 22.

The operation of the electric blower constructed as described above will be described. The air entering from the intake port 34 is in a violent turbulent state in the air passage 35 because the impeller 22 rotates at a high speed exceeding 30,000 rpm. Further, there is a considerable pressure difference between the blades 22 on the rotation direction side and the rotation direction opposite side, and a vortex flow is also generated.

However, the turbulent flow and eddy current near the wall surface are rectified and buffered by the rectifying effect of the fine grooves 31, 32, and 33, so that the turbulent boundary layer 36 is suppressed and the effective air passage cross-sectional area is increased. Connect. Also, the grooves 31, 3
Regarding the cross-sectional shapes of 2, 33, a trapezoidal shape, a corrugated shape, and the like are effective in addition to the V-shape.

As described above, according to the present embodiment, the air passage 35
By providing the fine grooves 31, 32, 33 on the inner wall in substantially the same direction as the air flow, the efficiency of the electric blower can be increased and the noise can be reduced.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. 4 and 5, reference numeral 41 denotes a centrifugal impeller having a plurality of blades 42, a front shroud 51 and a rear shroud 54 sandwiching the blades 42, and an air guide 43 is provided below the impeller 41. ing. The casing 44 includes the impeller 41 and the air guide 43.
Is mounted on the motor frame of the motor 47. The diffuser 45 formed by the casing 44 and the air guide 43 is disposed so as to have a passage that expands toward the outer periphery, and a return passage 46 is formed to smoothly and independently communicate with the end of the diffuser 45 independently.
The air flowing from the return passage 46 is
It is discharged from the exhaust hole 48 while cooling the inside.

The front shroud 51 of the casing 44
A fine groove 50 having a V-shaped cross section is arranged on a concentric circle with the motor shaft 49 on the inner wall surface facing the motor shaft 49. In addition, impeller 41
Similarly, on the outer wall surface of the front shroud 51 facing the casing 44, a fine groove 52 having a V-shaped cross section is arranged concentrically with the motor shaft 49.

The operation of the electric blower configured as described above will be described. Since the impeller 41 rotates at a high speed exceeding 30,000 rpm, a turbulent boundary layer 53 is developed on the inner wall surface of the casing 44 and the outer wall surface of the front shroud 51. In consideration of the thickness of the turbulent boundary layer 53, In the example, a gap 55 of 3 to 4 mm is provided between the casing 44 and the front shroud 51.

However, in the embodiment of the present invention, the turbulent boundary layer 53 can be made thinner by suppressing the turbulent flow due to the rectifying effect of the grooves 50 and 52 by the above configuration, and as a result, the gap between the casing 44 and the front shroud 51 can be reduced. 55 can be reduced.

Further, the grooves 50 and 52 are
Since the air in the gap 55 surrounded by the outer wall of the front shroud 51 and the inner wall of the casing 44 also forms a flow along the grooves 50 and 52, the impeller 4
The leakage loss due to the secondary flow of No. 1 can be suppressed.

As described above, according to the configuration of the present embodiment, the gap 55 between the casing 44 and the front shroud 51 can be narrowed, and the air in the gap 55 surrounded by the outer wall of the front shroud 51 and the inner wall of the casing 44 can also be reduced. Groove 50,
Since the flow along the flow 52 is formed, leakage loss due to the secondary flow of the impeller 41 can be suppressed, and the efficiency of the electric blower can be improved.

[0027]

As described above, according to the electric blower of the present invention, the space between the blades of the impeller and the inner wall of the air passage formed by the front and rear shrouds are arranged along the flow of air from the air intake side to the air outlet side. By providing the groove, the turbulence near the inner wall of the air passage is rectified to suppress the vortex and increase the air volume by reducing the thickness of the turbulent boundary layer and provide a low-noise electric blower.

Further, by providing grooves on the outer wall of the front shroud and the inner wall of the casing concentrically with the motor shaft, the gap between the casing and the impeller can be reduced. Further, since this groove is arranged concentrically with the motor shaft, the air in the gap surrounded by the outer wall of the front shroud and the inner wall of the casing also flows along the groove,
The loss due to the secondary flow of the exhaust flow of the impeller can be reduced, and a highly efficient electric blower can be provided.

[Brief description of the drawings]

FIG. 1 is a front view showing a partial cross section of an electric blower according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged perspective view of an impeller of the electric blower.

FIG. 3 is a partially enlarged sectional view of an impeller of the electric blower.

FIG. 4 is an exploded perspective view showing a partial cross section of the electric blower according to the second embodiment of the present invention.

FIG. 5 is a partially enlarged sectional view of the electric blower.

FIG. 6 is a front view showing a cross section of a part of a conventional electric blower.

[Explanation of symbols]

 21, 41 Impeller 22, 42 Blade 27, 51 Front shroud 28 Rear shroud 31, 32, 33, 50, 52 Groove 49 Motor shaft

Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI F04D 29/66 F04D 29/66 M (56) References JP-A-58-41298 (JP, A) JP-A-60-166793 (JP, A JP-A-61-259096 (JP, A) JP-A-2-64300 (JP, A) JP-A-63-160400 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04D 29/18-29/38

Claims (2)

(57) [Claims] 1. A motor, comprising: a motor; and a casing attached to a motor frame of the motor and including an impeller and an air guide. The impeller has a plurality of blades between a front surface and a rear shroud. A groove is provided on the surface of the blade in the same direction as the air flow from the inlet side end to the outlet side end, and a groove is also provided on the inner wall surface of the front and rear shrouds in the same direction as the air flow. Blower. 2. A motor, comprising: a motor; and a casing attached to a motor frame of the motor, the casing including an impeller and an air guide. The impeller has a plurality of blades between a front surface and a rear shroud. An electric blower in which grooves are formed concentrically with the motor shaft on the outer wall surface of the shroud and the inner wall surface of the casing.