JPH06108993A - Impeller for motor-driven blower - Google Patents

Abstract

PURPOSE:To provide an impeller for a motor-driven blower formed designed to reduce high frequency sound and eliminate discomfort. CONSTITUTION:A first means has a sunshade-shape front shroud 8 with an opening at the center part, and a disc-shape rear shroud. Plural fan blades 10 are provided between the front shroud 8 and the rear shroud, and the outer periphery of the front shroud 8 is provided with a slit 13 fromed along the front face side of the fan blade 10 in relation to the rotating direction. A second means is formed by providing a cutout at the tip upper part of the fan blade 10 at the outlet of an impeller 7, that is, on the front shroud 8 side.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, noise reduction of electric vacuum cleaners has become remarkable, and electric vacuum cleaners having a suction motor and a main body for noise reduction have become mainstream.

Conventionally, the impeller of this type of electric blower has generally been constructed as shown in FIGS. The configuration will be described below with reference to the drawings.

As shown in the figure, the impeller 1 comprises a front shroud 2, a rear shroud 3 and a fan blade 4. The fan blade 4 is caulked by a claw 5 to the front shroud 2 and the rear shroud 3. The impeller 1 is attached to a shaft (not shown) of an electric blower, and an air guide 6 is arranged so as to cover the entire circumference of the impeller.

In the above structure, when the electric blower is operated, the impeller 1 attached to the shaft rotates at high speed,
The air inside the impeller 1 is blown out to the outer periphery by centrifugal force, and the inlet of the impeller 1 becomes negative pressure. With this, a large suction force is obtained.

[0006]

However, such a conventional impeller for an electric blower has a problem that high-frequency noise from the electric blower tends to be high. That is, since the suction motor has been increased in output with the recent increase in power of vacuum cleaners, the motor has a larger air volume and a higher vacuum pressure, and the pressure at the impeller outlet is also increased. There is. Since the front surface of the fan blade 4 is in the direction of pressing air with respect to the rotating direction of the impeller 1, the pressure is high and the flow velocity is also high. On the contrary, the back surface of the fan blade 4 has a lower pressure and a slower flow velocity than the front surface. Further, since the impeller 1 has an umbrella shape, the flow velocity on the front shroud 2 side is fast and the pressure is high. The airflow from the impeller 1 is the air guide 5
However, since there is a pressure difference between the front surface and the back surface of the fan blade 4 as described above, the compression wave of the air flow collides with the air guide 6 only a number of times of the fan blade 4 during one rotation of the impeller 1. Become. The impact of the compressional waves is converted into sound and felt as high-frequency sound by the electric blower. Usually, the electric blower rotates 30,000 to 36000 rpm and the number of fan blades is 7 to 11, so the high frequency sound generated is 3 to 5 kHz, which is very audible to the ears, which is very annoying.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an impeller for an electric blower that produces less high-frequency noise and does not cause discomfort.

[0008]

The first means of the present invention for achieving the above object comprises an umbrella-shaped front shroud having an opening in a central portion and a disc-shaped rear shroud. A plurality of fan blades are provided between the shroud and the rear shroud, and a slit is provided on the outer circumference of the front shroud along the front side of the fan blade with respect to the rotation direction. A notch is provided in the upper part of the tip of the fan blade, that is, on the front shroud side.

[0009]

In the first means of the present invention described above, the front shroud is provided with a slit along the front surface side of the fan blade with respect to the rotation direction, so that a part of the air flow in the impeller blows out from the slit. The pressure on the front side of the outer periphery of the blade is reduced, and the high frequency sound is reduced.

In the second means, since the notch is provided above the fan blade tip of the impeller outlet, that is, on the front shroud side, the air flow is dispersed from the notch to the front surface to the back surface of the fan blade outer periphery, and the pressure difference is reduced. However, high frequency sound is reduced.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2, the impeller 7 comprises a front shroud 8, a rear shroud 9 and a fan blade 10. The fan blade 10 is caulked by a pawl 11 to the front shroud 8 and the rear shroud 9. The impeller 7 is attached to a shaft (not shown) of an electric blower, and an air guide 12 is arranged so as to cover the entire circumference of the impeller. In the first embodiment, a slit 13 is provided on the outer periphery of the front shroud 8 along the front side of the fan blade 10 in the rotational direction. In the second embodiment, the upper end of the fan blade 10 at the outlet of the impeller 7, that is, the front shroud 8
A notch 14 is provided on the side.

In the above structure, when the electric blower is operated, the impeller 7 attached to the shaft rotates at high speed,
The air inside the impeller 7 is blown out to the outer periphery by centrifugal force, and the inlet of the impeller 7 becomes negative pressure. As a result, a large suction force is obtained.

In the first embodiment, the front shroud 8
Since a slit 13 is provided on the outer periphery of the fan blade 10 along the front side of the fan blade 10 in the rotational direction, a part of the air flow in the impeller 7 is blown out from the slit 13 and the pressure on the upper front side of the outer periphery of the fan blade 10 is reduced. To do. Then, the pressure difference between the front surface and the back surface of the fan blade 10 becomes small, the degree of density of the air flow blown out from the impeller 7 is relaxed, and the high frequency sound when the air flow collides with the air guide 12 is reduced.

In the second embodiment, since the notch 14 is provided above the tip of the fan blade 10 at the outlet of the impeller 7, that is, on the front shroud 8 side, the air flow from the notch 14 to the front surface to the rear surface of the outer periphery of the fan blade 10. , The pressure difference is reduced, the degree of pressure density of the air flow blown out from the impeller 7 is relaxed, and the high frequency sound when the air flow collides with the air guide 12 is reduced.

[0016]

As is apparent from the above embodiment, according to the first embodiment of the present invention, the outer periphery of the front shroud is provided with the slit along the front side of the fan blade with respect to the rotation direction. A part of the air flow in the impeller is blown out from the slit, the pressure on the front side upper part of the outer periphery of the fan blade is reduced, and the high frequency sound is reduced.

According to the second embodiment, since the notch is provided in the upper part of the fan blade tip at the impeller outlet, that is, on the front shroud side, the air flow is dispersed from the notch to the front surface to the rear surface of the fan blade outer periphery, and the pressure is increased. The difference is reduced and the high frequency sound is reduced.

Therefore, it is possible to provide an impeller of an electric blower with less high frequency noise and no discomfort.

[Brief description of drawings]

FIG. 1 is a front view showing the structure of an impeller according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the internal structure of the impeller in the second embodiment of the present invention.

FIG. 3 is a front view showing the structure of a conventional impeller.

FIG. 4 is a sectional view showing the internal structure of a conventional impeller.

[Explanation of symbols]

 7 Impeller 8 Front shroud 10 Fan blade 13 Slit 14 Notch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Kato 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A front shroud having an umbrella-shaped front shroud having an opening in the center and a disc-shaped rear shroud, wherein a plurality of fan blades are provided between the front shroud and the rear shroud. Is an impeller of an electric blower in which a slit is provided along the front side of the fan blade with respect to the rotating direction. 2. An impeller for an electric blower, wherein a notch is provided on an upper portion of a fan blade tip at an impeller outlet, that is, on a front shroud side.