JPH05321892A - Impeller for axial flow blower - Google Patents

Abstract

PURPOSE:To reduce a fluid noise by forming a cross sectional shape of blades having a round front end part in a thick blade shape. CONSTITUTION:A cross sectional shape of a plural number of blades 9 constituting an impeller 8 is formed in a thick blade shape. Assuming that an outside diameter of this impeller 8 is D and a diameter of a hub 2 is (d), the maximum blade wall thickness T of the blade cross sectional surface in a part of a radius [R=((D<2>+d<2>)/2)<0.5>/2] is set in 5-12% of a blade chord length C of this blade cross sectional surface. In this way, even if the impeller 8 having the blades 9 is rotated in the prescribed rotational direction A and air is flowed into the impeller 8 from the B1 and B2 directions, since the blades 9 have a proper round wall thickness in the front end part 10, the air is not separated so largely from the front end part 10 of the blades 9 that a fluid noise can be restrained low.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reducing noise of an axial blower used in an air conditioner or the like.

[0002]

2. Description of the Related Art In recent years, an impeller of an axial blower has been widely used as a blower such as a separate type air conditioner from commercial use to household use, and there is a tendency for further noise reduction.

Hereinafter, with reference to the drawings, JP-A-63-
An impeller of a conventional axial flow fan as proposed in Japanese Patent No. 61800 will be described.

5 to 7 show the structure of a conventional impeller of an axial flow fan. 1 is an impeller, 2 is a substantially cylindrical hub, 3 is a plurality of blades arranged around the hub 2, and as shown in FIG. , Is formed in a thin plate shape having a substantially uniform thickness. Reference numeral 6 is an orifice that surrounds the plurality of blades 3.

The operation of the impeller of the axial blower configured as above will be described below.

When the impeller 1 rotates in a predetermined rotation direction A, air flows into the impeller 1 and static pressure and dynamic pressure are applied by the action of the blades 3 and the air is discharged to the outside of the impeller 1 to blow air. To make.

When this is seen in the U-U cross section of the blade 3, the air flow is as shown in FIG. B represents the direction of the flow of the air flowing into the blade 3, but the design of the blade 3 is such that at such an inflow angle B, separation, which is one of the causes of fluid noise, is most unlikely to occur. Designed.

[0008]

However, the above-mentioned configuration has the following problems.

In the actual flow of the blower, the inflow angle fluctuates as shown by B ₁ and B _{2 in} FIG. 7, and does not always flow in the B direction as designed. Therefore, in the blade 3 designed assuming the average flow direction B, large separation such as E temporarily occurs with respect to the inflow at the angles B ₁ and B ₂ , and fluid noise is generated. To do. There is a problem that such a separation that causes noise cannot be prevented even with an optimized blade design, with a uniform thin blade as in the conventional example.

The present invention is intended to solve such a conventional problem, and provides a blade cross-sectional shape which is less likely to cause separation due to fluctuations in the flow, thereby providing an impeller of an axial blower. It is intended to significantly reduce noise.

[0011]

In order to solve the above problems, an impeller of an axial blower according to the present invention has a plurality of blades forming an impeller having a thick blade-shaped cross section, and an outer diameter of the impeller. Is D and the hub diameter is d, the radius R = ((D ² + d ² ).
/ 2) Maximum blade thickness T at the blade section of ^0.5 / 2
Is 5 to 12% of the chord length C of the blade cross section.

[0012]

With this configuration, when the vane wheel outer diameter is D and the hub diameter is d, the radius R = ((D ² +
d ² ) / 2) The maximum blade thickness T in the blade cross section of ^0.5 / 2 is 5 to 12% of the chord length C of the blade cross section, so that the blade thickness in the actual blower is Even if the inflow angle at a certain point inflows in the B ₁ and B ₂ directions shown in FIG. 7 due to such flow fluctuations, a large separation like E is unlikely to occur, and a fluid noise reduction effect can be obtained. ..

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same parts as those of the conventional example are denoted by the same reference numerals to avoid duplication, and the description thereof will be omitted.

First, FIGS. 1 to 3 illustrate the structure of an impeller of an axial blower according to an embodiment of the present invention. 8 is an impeller of an axial blower, 9 is a plurality of blades,
In the blade 9, 10 is a leading edge and 11 is a trailing edge. Also,
The dashed-dotted line Y-Y has a radius R = ((D ² + d ² ) / 2) ^0.5.
The arc of / 2 is shown.

FIG. 3 shows a blade cross-sectional shape at this radius R. In the same sectional view, the blade section of the impeller of the present invention has a thick blade shape. Further, in the sectional view, the maximum wall thickness T of the blade cross section of the impeller of the present invention is 5 to 12% of the chord length C of the blade cross section.

The operation of the impeller of the axial blower configured as above will be described below.

When the impeller 8 rotates in a predetermined rotation direction A, air flows into the impeller 8 and static pressure and dynamic pressure are added by the action of the blades 9 and the air is discharged to the outside of the impeller 8 to blow air. To make.

When this is seen in the YY cross section of the blade 9, the air flow is as shown in FIG. B represents the direction of the flow of the air flowing into the blade 9, but the design of the blade 9 is such that the separation, which is one of the causes of fluid noise, is most unlikely to occur at such an inlet angle B. Designed.

However, in the flow of an actual blower,
The inflow angle fluctuates as B ₁ and B ₂ in FIG. 3, and the inflow angle does not always flow in the B direction as designed. However, in the blade 9 according to the present invention, which has a rounded front edge and an appropriate thickness, a large separation E unlike a thin blade does not occur even when an inflow of angles in the B ₁ and B ₂ directions occurs. Therefore, the fluid noise can be suppressed low.

The above effect is affected by the maximum wall thickness T in the blade cross section at the radius R, which is representative of the thickness of the blade 9. The result is shown in FIG. 4, where T> 0.
The above effect can be obtained by setting the temperature to 05C.
Further, as the blade thickness increases, problems such as impeller strength and product weight increase, so T <0.12C is appropriate.

[0021]

As described above, in the impeller of the axial blower according to the present invention, the plurality of blades forming the impeller have thick blade cross-sections, the outer diameter of the impeller is D, and the hub diameter is d. And when
The maximum blade thickness T in the blade cross section of the radius R = ((D ² + d ² ) / 2) ^0.5 / 2 is 5 to 1 of the chord length C of the blade cross section.
Since it is set to 2%, there are no major problems in the strength of the impeller and the product weight, and even if the flow changes when it is installed in an actual machine, large separation does not occur, and fluid noise can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of an impeller of an axial blower according to an embodiment of the present invention.

FIG. 2 is a sectional view of an impeller of an axial blower according to an embodiment of the present invention.

FIG. 3 is a sectional view taken along line YY of FIG.

FIG. 4 is a graph showing the relationship between the maximum blade thickness T and the blast noise in the Y-Y sectional view of FIG.

FIG. 5 is a plan view of an impeller of a conventional axial blower.

FIG. 6 is a cross-sectional view of an impeller of a conventional axial blower.

FIG. 7 is a sectional view taken along line U-U of FIG.

[Explanation of symbols]

 1 Impeller 2 Hub 3 Blade 4 Orifice 8 Impeller 9 Blade 10 Leading Edge 11 Trailing Edge

Claims (1)

[Claims] 1. A radius R = ((D ² + d ² ) /, where D is the outer diameter of the impeller and d is the hub diameter. 2) The maximum blade thickness T in the blade section of ^0.5 / 2 is 5 of the chord length C of the blade section.
Axial blower impeller that is ~ 12%.