JPS59105998A - Axial flow fan - Google Patents

Abstract

PURPOSE:To restrict generation of blade end vortex and reduce noise without decreasing an axial flow speed near the tip end of the blade by a method wherein both of the suction and delivery side surfaces of the tip end of the blade are provided with guides to change the direction of airflow. CONSTITUTION:When the fan blade 2 rotates into the arrow sign direction in the diagram, the angles of incidence at both ends 5, 9 in the front side of the rotating direction of the fan are zero degree. A flowout angle alpha at the end part 6 in the rear side of the rotating direction of the fan and the flowout angle beta at the end part 10 are about 10-80 degrees and 20-30 degrees are the optimum among those angles. Accordingly, the guide 5 of the suction side surface 3 is concave with respect to the centrifugal direction while the guide 8 of the delivery side surface 7 is convex with respect to the centrifugal direction. The widths of the guides 5, 9 are 2-10mm.. Air flows along the guide 4 at the suction side surface 3 centrifugally by the rotation of the fan, but the same flows centripetally along the guide 8 at the delivery side surface 7, and these airflows are cancelled mutually. Accordingly, the blade end vortex may be attenuated remarkably and the noise may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an axial flow fan, and is effective for use as, for example, a radiator fan for an engine, a fan for a ventilation fan, and a fan for an electric fan.

In the past, various low-noise fans have been devised, some of which increase the axial velocity by increasing the blade attachment angle near the blade tip.
There was one that attempted to reduce noise by reducing the interference of the blade tip vortices with the blade.

However, in this type of blade, because the blade attachment angle is increased, the lift force changing force at the blade tip increases, and the temperature of the blade tip vortex increases accordingly.As a result, the pressure change on the blade surface increases, and the noise force increases. There was a problem that occurred.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a low-noise axial flow fan by reducing the axial velocity near the tip of the blade, thereby suppressing the generation of vortices in the blade a. .

In order to achieve this objective, the present invention provides guides for changing the direction of airflow on both the suction side and the discharge side of the wing tips 6B, The air was made to flow in the direction of the air at the discharge side.

Next, a first embodiment of the present invention in which the present invention is applied to a radiator fan will be described with reference to the drawings.

Fig. 1 shows the suction side of the axial fan 1, and the axial fan 1 rotating in the direction of the arrow in the figure is placed on the suction side 3 of the fan blade 2, which has a heat shield. There are 4 walls. This guide 4 is located at 011 in front of the fan rotation direction.
The distance to the rotation center of the axial fan 1 gradually increases from the first part 5 toward the rear end 6 in the fan rotation direction.

FIG. 2 shows the discharge side of the axial fan 1, which rotates in the direction of the arrow in the figure. A guide 8 is also provided on the discharge side surface 7 of the fan blade 2. This guide 8
The distance to the rotation center of the axial fan 1 gradually increases from the rear end 9 in the fan rotation direction to the front end 1o in the fan rotation direction.

That is, as shown in FIG. 3, when the fan blade 2 rotates in the direction of the arrow in the figure, the front end 5.
The inflow angle at 9 is 0''.

Further, the outflow angle α at the rear end 6 in the rotational direction of the fan and the outflow angle β at the end 10 are both approximately 10' to 80°, with an optimal range of 20° to 30'. Therefore, the guide 5 on the suction side 3 is concave in the centrifugal direction, and the guide 8 on the discharge side 7 is convex in the centrifugal direction. In addition, this guide 5.8
The width is 2 to 10 dragons.

FIG. 4 is a perspective view of the fan blade 2, and the shapes of the guides 4 and 8 provided on the fan blade 2 are clearly seen from this figure.

FIG. 5 is a cross-sectional view of the fan blade 2.

The material used for this fan is polypropylene.

Next, the operation when the axial fan configured as described above is disposed as a radiator fan between an engine and a radiator will be explained in relation to the operation of a conventional fan without a guide.

When a conventional fan 1 as shown in FIG. 6 rotates, negative pressure is generated on the suction side 3 of the fan blade 2 as shown in FIG. Therefore, a pressure difference occurs between the discharge side surface 3 and the suction side surface 7, and air flows from the discharge side surface 7 to the suction side surface 3 due to the pressure difference. As a result, a blade tip vortex 11 is generated, and as shown in FIG.
This caused interference with the surface of the rear fan blade 2', causing noise. Therefore, in the present invention, when the fan rotates by receiving rotational force from the engine or motor, the air flowing through the radiator due to the rotation flows in the centrifugal direction along the car (F4) at the suction side 3, and in the centrifugal direction along the direction F4 at the discharge side 7. 8 toward the center.In other words, this air flow is opposite to the air flowing from the discharge side 7 to the suction side 3 when there is no kite.Therefore, these air flows Therefore, the blade tip vortex is significantly attenuated, and there is no interference with the rear fan blade 2' of the fan blade 2 where the blade tip vortex was generated, reducing noise.

Figure 9 shows the noise measurement results by the inventors.
Conventional axial flow fan (solid line A) and this example (71ij+h
This is a comparison of the noise level with a flow fan (dashed line). From FIG. 9, it is clear that the noise in the frequency range lKH2 to 5 KHz, which is the turbulent noise component due to the blade tip vortices, is reduced.

In this embodiment, one guide is provided on each side of the fan blade 2, but a plurality of guides may be provided as shown in FIG.

Further, as shown in FIG. 11, the guide may be separated into a plurality of parts and arranged in the middle.

Furthermore, when the blade thickness is relatively thick as shown in FIG. 12, the kite may be configured by changing the blade thickness. FIG. 13 is a cross-sectional view of FIG. 12. 13th
As shown in the figure, a thick blade portion 12 is provided on the discharge side surface 7, and the height dl of the thick blade portion 11 increases from the front end to the rear end in the rotational direction. Further, a groove portion 13 is provided on the suction side surface 3, and the length d2 of this groove portion 12 is decreased from the front wheel toward the rear end in the rotational direction. This thick part of the wing thickness 1
2 and the groove portion 13 constitute a guide and reduce noise.

[Brief explanation of drawings]

1 to 5 show a first embodiment of the present invention, FIG. 1 is a front view of an axial fan seen from the suction side, FIG. 2 is a front view of the axial fan seen from the discharge side, ff Figure 13 is a front view of the main part of the fan blade, Figure 4 is a perspective view of the main part of the fan blade,
Fig. 5 is a cross-sectional view of a fan blade, Figs. 6 to 8 show a conventional axial flow fan, Fig. 6 is a front view, and Figs. 7 and 8 are blade tips formed at fan brake 1'. 9 is a diagram showing the noise level of the conventional axial fan and the axial fan of the first embodiment, and FIG. 10 is a diagram showing the second embodiment of the present invention. Blade main part front view, f
FIG. 12 is a front view of the main part of a fan blade showing a third embodiment of the present invention, FIGS. 12 and 13 are a front view of the main part of a fan blade, and FIG. FIG. 13 is a cross-sectional view of FIG. 12. 1...Boss, 2...Fan blade, 4.8...
guide. Representative Patent Attorney Takashi Okabe Figure 4 Figure 5 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11

Claims (1)

[Claims] It has a boss and a plurality of fan blades arranged around the boss, and has a fan blade on the suction surface side of the fan blade that gradually moves away from the center of rotation of the fan from the front wheel toward the rear end in the direction of rotation of the fan blade. An axial flow fan characterized in that a guide is provided on the discharge surface side so that the guide gradually becomes farther from the fan rotation center from the rear end in the fan blade rotation direction toward the front end.