JPH06108997A - Axial fan - Google Patents

Abstract

PURPOSE:To reduce the separation of flow at the rear edge of a blade so as to reduce noise by providing a thick plane part largest in circumferential cross section at a part of the rear edge back face side in the circumferential cross section of a blade within a range close to a blade hub from the outer diameter. CONSTITUTION:In an air blower or a ventilator 1, an axial fan 2 is locked to the shaft 5 of a motor 4 fitted into a body 3. The blade 6 of this axial fan 2 is provided with a thick plane part 10 largest in circumferential cross section with circumferential length l of 2-30% on the back face side 9 of the rear edge 8 in a range close to a blade hub 7 from the outer diameter. With this constitution, when the axial fan 2 is rotated by the motor 4, air sucked from a suction port 11 is going to generate separation on the back face side 9 of the largest warp point 12 of the blade 6, but the separation is reduced by the thick plane part 10 so as to reduce the generation of noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial flow fan used for ventilation blowers and the like.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for noise reduction for ventilation and ventilation equipment and air conditioning equipment used in residential and non-residential spaces.

Conventionally, in this type of axial fan, as shown in FIG. 6 and FIG. 7, the circumferential cross section of the blade 101 is one arc blade or a plurality of arc blades at any radial position of the axial fan 102. It is a thin-walled wing type, and the thickness is only 1 chord length, only the chord length 103 differs due to the change in the radial position.
03 in proportion to the maximum thickness 107,
It was configured to be set to 20% to 50% from No. 8.

[0004]

In such a conventional axial fan, the flow does not follow the surface of the blade 101, and a separated flow 106 is generated on the rear surface side 105 at the trailing edge 104 of the blade 101, and noise is increased. There was a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an axial fan with low noise used in home appliances and equipment.

[0006]

In order to achieve the above object, the axial fan according to the present invention has a first means, which is a rear surface of a trailing edge of a blade circumferential section within a range from an outer diameter to the vicinity of a blade hub. On the side, the thickest flat surface portion having a circumferential length of 2% to 30% from the trailing edge with respect to the chord length and having the largest circumferential cross section is provided.

The second means is such that a maximum wall thickness apex portion is provided in the range of 60% to 90% from the front edge of the chord length on the back side of the rear edge of the blade circumferential cross section.

[0008]

According to the present invention, the vortices emitted from the rear end portion of the blade are extremely small and the noise due to the vortices can be reduced by the constitution of the above-mentioned first and second means.

[0009]

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

As shown in the figure, 1 is a blower or a ventilation fan, and an electric motor 4 having an axial fan 2 attached inside a main body 3.
Is locked to the shaft 5. The blade 6 of the axial fan 2 has a circumferential section of 2% to 30% on the rear side 9 of the trailing edge 8 in the range from the outer diameter to the vicinity of the blade hub 7 as shown in FIG. 1 is the thickest flat surface portion 10 in the circumferential cross section.

With the above structure, when the axial fan 2 is rotated by the electric motor 4, the air sucked from the suction port 11 tends to peel off on the back side 9 of the maximum warp point 12 of the blade 6, but the wall thickness is increased. Since the flat surface portion 10 is provided, peeling is reduced and noise generation can be reduced.

FIG. 3 shows changes in air volume and noise when the length 1 of the thick flat surface portion 10 is changed. Thereby, the optimum value of the length of the thick flat surface portion 10 was determined. Also, the trailing edge 8
The noise due to the turbulence is increased as the peripheral speed is higher, and the generated sound is proportional to the sixth power of the peripheral speed. Therefore, the sound is determined by the size of the peripheral speed, and it is necessary to attach the thick flat surface portion 10 to the vicinity of the blade hub 7 regardless of the diameter of the blade hub 7 with respect to the blade having a certain outer diameter.

As described above, according to the axial flow fan of the first embodiment of the present invention, the generation of noise can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG.
The description will be made with reference to FIG.

The same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted. As shown in the figure, the blade 6 of the axial flow fan 2 has a chord length from the front edge 13 to 60% to the rear side 9 of the rear edge 8 of the circumferential cross section of the blade 6 in the range from the outer diameter to the vicinity of the blade hub 7. The maximum thickness peak portion 14 is provided in the range of 90%.

With the above structure, when the axial fan 2 is rotated by the electric motor 4, the air sucked from the suction port 11 tends to peel off on the rear surface 9 of the maximum warp point 12 of the blade 6, but the wall thickness is increased. Since the apex portion 14 is provided, peeling is reduced and noise generation can be reduced.

FIG. 5 shows changes in the air volume and noise when the position of the wall thickness apex portion 14 is changed. In this way, the optimum position for the position of the wall thickness apex portion 14 was determined. Also, the trailing edge 8
The noise due to the turbulence is increased as the peripheral speed is higher, and the generated sound is proportional to the sixth power of the peripheral speed. Therefore, the sound is determined by the size of the peripheral speed, and it is necessary to attach the thick apex portion 14 to the vicinity of the blade hub 7 regardless of the diameter of the blade hub 7 for a blade having a certain outer diameter.

As described above, according to the axial flow fan of the second embodiment of the present invention, noise generation can be reduced.

[0019]

As is apparent from the above embodiments, according to the present invention, the axial fan capable of reducing the flow separation at the trailing edge of the blade of the axial fan and reducing the noise in the ventilation fan or the blower. Can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an axial fan according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the blade

FIG. 3 is a diagram showing the relationship between the length of the same thickness plane portion and performance.

FIG. 4 is a sectional view of a blade according to a second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the position of the top portion of the same thickness and performance.

FIG. 6 is a sectional view of a conventional axial fan.

FIG. 7 is a sectional view of the blade

[Explanation of symbols]

 2 Axial fan 6 Blade 7 Blade hub 8 Trailing edge 9 Back side 10 Thick flat surface portion 13 Front edge 14 Maximum thickness apex portion

Claims (2)

[Claims] 1. A circumferential cross section having a circumferential length of 2% to 30% from the trailing edge with respect to the chord length on the back side of the trailing edge of the blade circumferential cross section within the range from the outer diameter to the vicinity of the blade hub. Axial fan with the thickest flat surface part. 2. The axial fan according to claim 1, wherein a maximum wall thickness apex portion is provided in the range of 60% to 90% from the front edge of the chord length on the back side of the rear edge of the blade circumferential cross section.