JPH08312592A - Opening part structure of casing for blower - Google Patents

Abstract

PURPOSE: To provide a blower capable of reducing noise produced in an opening part by air flow, by forming the opening part of a casing into a specified shape. CONSTITUTION: An opening of a recessed groove 16 having an approximately semicircular cross section is formed around an opening formed in a casing 10 to face the blast vane side. Further, a shallow bottom part 17 having the groove bottom shifted toward the inner side and the depth shallowed is formed near the throat part of the recessed groove in the casing. When a motor is rotated, blow vanes are rotated so that air sucked from the opening part 15 formed in a side plate 12 of the casing 10 is blown off from an outlet 18 of a casing 15 body through the blow vanes 13. Then, the air flow is changed in the opening part while the air flow circulating in the recessed groove 16 with the approximately semicircular cross section is stopped in the shallow bottom part formed in the opening part, so that noise is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blower casing used in, for example, an indoor unit of an air conditioner, office equipment, or industrial equipment such as a heating / cooling equipment using oil or gas, a boiler, and the like. More specifically, the present invention is applicable to a blower with a built-in motor, and relates to a casing opening structure of a blower that can reduce noise during blowing.

[0002]

2. Description of the Related Art The structure of a conventional blower is disclosed in Japanese Patent Application Laid-Open No. 5-28.
Taking the example described in Japanese Patent Publication No. 0497 as an example, FIG. 6 is a side sectional view of the air blower. In the figure,
In this fan, a plurality of blades 52 are annularly formed in the circumferential direction near the outer peripheral end of the bottom plate 51, and an annular holding ring 53 is formed on the top of this blade. The ceiling portion 55 of the case 54 for accommodating the centrifugal multi-blade fan is located near the height of the top portion of the centrifugal multi-blade fan, and the bell mouth 56 is formed by being raised from the ceiling portion 55. Bellmouth 5
6 is curved in a semi-circular shape, and is formed such that the inner diameter end hangs down to near the top of the centrifugal multiblade fan. With the multi-blade fan configured in this manner, it is possible to prevent the backflow that passes through the gap between the tops of the blades and the inner wall of the case, and the backflow or vortex of the air that flows between the blades. It is possible to prevent the generation of noise and reduce noise.

[0003]

By the way, recently, the awareness of noise has become more severe, and the above-mentioned countermeasures are not always sufficient. Therefore, the present inventor As a result of earnest research on noise reduction, noise in the air blower configured as described above is generated when wind blows near the opening of the casing in addition to the wind noise caused by the blades and the rotation noise of the motor. It is confirmed that the sound of the air flow is loud. Therefore,
As a result of further various experiments on the shape of the casing bell mouth, the present inventor has found that the noise generated in the opening due to the air flow can be reduced by forming the opening into a certain specific shape. The present invention has been made based on the above findings.

[0004]

Therefore, according to the present invention, a concave groove is formed around the opening for air intake formed in the casing of the blower toward the inside of the casing, and the throat of the casing of the concave groove is formed. It is characterized in that a shallow bottom portion having a shallow depth is formed near the portion by moving the groove bottom inward, and this is a means for solving the problem.

[0005]

Around the opening formed in the casing 1, an opening (bell mouth) of a concave groove 16 having a substantially semicircular cross section is formed so as to face the blower blade side, and further, the casing of the concave groove 16 is formed. A shallow bottom portion 17 is formed near the throat so that the groove bottom is moved inward to reduce the depth. Motor M
When the fan rotates, the blower blade 13 rotates, whereby the air sucked from the opening 15 formed in the side plate 12 of the casing 10 is blown out from the outlet 18 of the casing 10 main body through the blower blade 13. At this time, the air flow tries to flow back inside the bell mouth while changing at the opening,
Since this flow is stopped at the shallow bottom formed in the opening, noise is reduced.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view of a blower according to an embodiment of the present invention,
2 is a cross-sectional view taken along the line AA 'in FIG. 1, and FIG. 3 is a view as seen from the arrow B in FIG.

In the drawing, reference numeral 10 denotes a casing. A motor M is attached to one side plate 11 of the casing 10. Further, the output shaft 14 of the motor M has a large number of vanes 19 on its circumference. A well-known blower blade 13 having a cylindrical shape is attached. The other side plate 12 of the casing 10 is provided with an opening 15 for sucking air.

As shown in FIG. 2, the opening 15 is formed around the opening formed in the casing 10 so that the opening (bell mouth) of the concave groove 16 having a substantially semicircular cross section is directed toward the blower blade side. Further, in the vicinity of the throat portion of the casing of the concave groove 16, a shallow bottom portion 17 having a shallow depth is formed as shown in the drawing by moving the groove bottom inward. As shown in FIG. 1, the shallow bottom portion 17 has an angle α in the upper direction in the figure and an angle in the lower direction in the figure with reference to a line (O-C) connecting the rotation center of the blower blade and the lower end of the outlet of the blower casing. When β is β, it is effective that α ≦ 40 ° and β ≦ 40 °, and particularly 10 ° <α <20 °, 10 ° <β <20 °.
It is desirable that

In the above-mentioned blower, when the motor M rotates, the blower blades 13 rotate, so that the air sucked from the openings 15 formed in the side plate 12 of the casing 10 passes through the blower blades 13 to the outlet of the casing 10 main body. Blow out from 18. At this time, the air flow changes at the opening and tries to flow back inside the bell mouth formed in the opening, but this air flow is stopped at the shallow bottom of the bell mouth, resulting in reduction of noise. Will be.

Experimental data relating to noise and static pressure between the bell mouth according to the present invention and the conventional bell mouth are shown in FIGS. 4 and 5. This data is for α = 16 ° and β = 10 °. 4A shows noise data of a bell mouth having a shallow bottom, and FIG. 4B shows noise data of a conventional bell mouth having no shallow bottom. In each graph, the horizontal axis is the output and the vertical axis is the noise level. The numbers above the graph indicate the high noise level in the graph.
Zero peak values are taken out, and the corresponding output frequencies and noise levels are displayed in descending order.

For example, in a bell mouth having a shallow bottom,
As shown in (a), the noise when the output is 725HZ is the largest and is 46.84dB, the noise at 2500HZ is 45.47dB, and the noise at 1750HZ is 45.25dB. go. Also, in the conventional bell mouth without a shallow bottom, the output is 26 as shown in (b).
The maximum noise at 00HZ is 46.82 dB, and the noise levels are arranged in order of decreasing noise level. As is clear from FIG. 4, the noise level of the bell mouth having the shallow bottom is clearly lower than that of the conventional bell mouth having no shallow bottom. The reason for this can be presumed to be that the shallow bottom formed on the bell mouth affects the air flow inside the bell mouth, which changes the air flow around the opening to reduce noise. Even when the angle is further increased by about 20 to 30 ° from the above angle, the air flow that tries to recirculate in the bell mouth can be stopped, and as a result, noise can be reduced.

Further, the air flow rate representing the output efficiency shown in FIG.
In the static pressure characteristic curve, the bell mouth with the shallow bottom is clearly higher than the static pressure of the conventional bell mouth without the shallow bottom, and this data shows that the bell mouth with the shallow bottom has the shallow bottom. It can be seen that it is more efficient than the conventional bell mouth without.

Around the opening 15 formed in the casing 10 as described above, an opening (bell mouth) of a concave groove having a substantially semicircular cross section is formed so as to face the blower blade side, and
It was confirmed that noise is reduced and efficiency is increased by forming the shallow bottom portion 17 having a shallow depth by moving the groove bottom inward in the vicinity of the throat of the casing of the concave groove. The opening may be formed integrally with the casing, or a separate member may be attached to the casing body. Further, the blower blades arranged in the casing can naturally be applied to either the conventional type in which a motor is externally attached or the so-called built-in motor type in which a motor is incorporated in the blower blades. is there.

[0014]

As described above in detail, in the air blower according to the present invention, the bell mouth having a unique shape is formed in the air suction opening of the casing, so that the noise of the conventional air blower is significantly reduced. In addition, the efficiency can be significantly improved. Further, since the groove shape is simple, it can be processed by pressing, and excellent effects such as no labor for manufacturing can be achieved.

[Brief description of drawings]

FIG. 1 is a side view of an air blower according to the present invention.

FIG. 2 is a sectional view taken along the line AA ′ in FIG.

3 is a view on arrow B in FIG. 1. FIG.

FIG. 4 is experimental data on noise between an opening structure according to the present invention and a conventional opening structure.

FIG. 5 is experimental data relating to static pressure between the opening structure according to the present invention and the conventional opening structure.

FIG. 6 is a configuration diagram of an opening structure of a conventional blower.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Casing 11 Side plate 12 Side plate having an opening 13 Blower blade 15 Opening 16 Concave groove 17 Shallow bottom 18 Casing outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Endo 2-499 Aioi-cho, Kiryu-shi, Gunma Akaishi Metal Industry Co., Ltd.

Claims (2)

[Claims] 1. A concave groove is formed around an air intake opening formed in a casing of a blower toward the inside of the casing, and the groove bottom is formed inward in the vicinity of the throat of the casing of the concave groove. A casing opening structure of a blower, characterized in that a shallow bottom portion is formed by moving it to a lower depth. 2. The shallow bottom portion has an angle α in the upward direction and an angle β in the downward direction in the figure with respect to a line connecting the center of rotation of the blower blade and the lower end of the outlet of the blower casing. Α ≦
2. The casing opening structure for a blower according to claim 1, wherein the range is 40 ° and β ≦ 40 °.