JPH06229397A - Axial flow fan - Google Patents

Abstract

PURPOSE:To suppress increase of the cost while reducing noise, in an axial flow fan. CONSTITUTION:In an axial flow fan formed in such a way that a plurality of blades 24 are projected radially on the outer circumference of a fan boss 23, a thin wall part 25 whose thickness sized D is becoming gradually smaller than those of the other parts is formed on the top end side outer circumferential part 24a of each blade 24. Since the thin wall part 25 is formed on the top end side outer circumferential part where speed is most large at the time of rotation of the blade 24, the volume of wind cut sound is reduced so as to reduce noise. Since the thickness sizes of the other parts than the thin wall part 25 are ensured sufficiently, it is possible to suppress deformation thereof during rotation time. Furthermore, at the time of formation, it is possible to suppress deterioration of hot water flow, and obviate the necessity for having especially good performance as a forming device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial fan used for a wall ventilation fan or the like.

[0002]

2. Description of the Related Art This type of axial fan has a structure in which a plurality of blades are radially provided on an outer peripheral portion of a fan boss attached to a rotating shaft of a motor, and is generally integrally molded of synthetic resin. There is.

Thus, conventionally, as shown in FIG. 5, the blade 2 protruding from the fan boss 1 is formed so that the thickness dimension d thereof is uniform over the entire blade 2. In some cases, as shown in FIG. 6, the blade 3 is formed such that the thickness dimension d thereof is gradually reduced from the base end portion 3a to the outer peripheral portion 3b.

[0004]

However, in the configuration shown in FIG. 5 among the configurations described above, when the thickness dimension d of the blade 2 is large, the wind noise caused by the blade 2 is large and the noise is large. Conversely, when the thickness dimension d of the blade 2 is small, the bending strength of the blade 2 is weakened, so that the blade 2 is easily deformed under a relatively large pressure and the noise in the same air volume is large. There was a problem that

On the other hand, the one shown in FIG. 6 has a drawback in that the flow of molten metal at the time of molding is bad, and the performance of the molding apparatus needs to be one rank higher, which results in higher cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an axial flow fan which can reduce noise and can suppress an increase in cost.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an axial flow in which a plurality of blades are radially projected on the outer peripheral portion of a fan boss attached to a rotary shaft. The fan is characterized in that a thin-walled portion whose thickness dimension is gradually smaller than that of the other portions is formed on the outer peripheral portion on the tip side of each blade.

In this case, when the radial length dimension from the base end portion to the outer peripheral edge portion of the blade is R, and the width dimension of the thin portion is t, the value of t / R is 0.05 to 0. It is preferable to set it within the range of 4.

[0009]

According to the above-described means, when the axial fan is rotated, the thin portion is formed on the outer peripheral portion on the tip end side, which is the fastest portion of the blade, so that the area that is resistant to air is reduced. As a result, the wind noise is reduced, which in turn reduces noise.

Further, in the blade, since the thickness dimension of the portion other than the thin portion can be sufficiently secured, the strength can be secured and the deformation during rotation can be suppressed. Further, at the time of molding, since the thickness dimension of the portion other than the thin portion can be sufficiently secured, it is possible to prevent the molten metal flow from being deteriorated, and it is not necessary that the molding apparatus has particularly good performance. .

In this case, the value of t / R, which is the ratio of the radial length dimension R from the base end portion to the outer peripheral edge portion of the blade and the width dimension t of the thin portion, is 0.05 to 0. From the experimental results, it was found that noise can be effectively suppressed by setting the value within the range of 4.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, FIG. 3 shows a vertical side view of the ventilation fan 11 installed on a wall of a room or the like. In FIG. 3, a motor 14 is attached to the main body frame 12 of the ventilation fan 11 via a mounting frame 13, and an axial fan 15 having a structure described later is attached by a knob 16 to a tip end portion of a rotation shaft (not shown) of the motor 14. It is attached.

A decorative frame 18 having a bell mouth 17 surrounding the axial fan 15 on the front side (inside the room) of the main body frame 12.
Is detachably attached, and 3 is attached to the rear surface side of the main body frame 12.
A single shutter 19 is rotatably attached. Further, a switch box 20 is provided in the lower portion of the decorative frame 18, and the pulling operation of the drawstring 21 hanging from the switch box 20 controls the motor 14 to be turned on and off and the L-shaped lever 22. The shutter 19 is opened and closed via the.

As shown in FIG. 2, the axial fan 15 radially projects a plurality of blades 24, for example, five blades 24, on the outer peripheral portion of the fan boss 23 attached to the rotating shaft of the motor 14. The structure is provided, and is integrally molded of synthetic resin.

Each blade 24 has a tip-side outer peripheral portion 2
4a and the front end side outer peripheral portion 24b, as shown in FIG.
The thin portion 25 is formed so that the thickness dimension D is gradually smaller than that of the other portion, and the boundary portion 25a between the thin portion 25 and the other portion is formed so that the surface becomes smooth. There is.

In this case, the length dimension in the radial direction (radial direction passing through the center of the fan boss 23) from the base end portion of the blade 24 to the outer peripheral edge portion is R, and the radial direction of the thin-walled portion 25 at the tip side outer peripheral portion 24a. The value of t / R is set to fall within the range of 0.05 to 0.4, where t is the width dimension of.

In the above structure, when the axial fan 15 is rotated by the motor 14 in the direction of arrow A, the air is sucked from the front and discharged to the rear by the blowing action of each blade 24.

Here, in this embodiment, when the axial fan 15 is rotated, the thin portion 25 is formed on the tip-side outer peripheral portion 24a, which is the fastest portion of the blade 24. The area of resistance can be reduced,
Along with this, wind noise is reduced, and noise can be reduced. In this case, in the blade 25, the thin-walled portion 25 is also formed on the front end side outer peripheral portion 24b which is the tip end in the rotation direction, so that the wind noise can be further reduced, and the noise can be further reduced.

Further, in the blade 24, the thin portion 25
Since the thickness dimension D of other parts other than can be sufficiently secured,
The strength can be secured, deformation during rotation can be suppressed, and noise in the same air volume can be reduced. Further, at the time of molding, since the thickness dimension D of the portion other than the thin portion 25 can be sufficiently secured, it is possible to prevent the molten metal flow from being deteriorated, and to improve the performance of the molding device. There is no need, and the increase in cost can be suppressed.

FIG. 4 shows the radial length R from the base end of the blade 24 to the outer peripheral edge and the width t of the thin portion 25.
5 shows an experimental result of the relationship between the value of t / R, which is the ratio of the value of and, and noise (noise at the same air volume). This Figure 4
As is apparent from the above, noise can be effectively reduced by setting the value of t / R in the range of 0.05 to 0.4.

[0021]

According to the axial fan of claim 1,
By forming a thin-walled part, whose thickness is gradually smaller than other parts, on the outer peripheral part on the tip side of the blade, it is possible to reduce wind noise and reduce noise. It is possible to prevent the flow from becoming worse, and to suppress an increase in cost.

According to the axial fan of the second aspect, the radial length R from the base end portion to the outer peripheral edge portion of the blade is R.
And the value of t / R, which is the ratio of the width dimension t of the thin portion, is 0.0
By setting it to be within the range of 5 to 0.4,
Noise can be effectively suppressed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a cross-sectional view taken along line XX in FIG.

FIG. 2 is a front view of an axial fan.

[Figure 3] Vertical side view of the ventilation fan

FIG. 4 is a characteristic diagram showing an experimental result of a relationship between noise and a value of t / R, which is a ratio of the radial length R of the blade to the width t of the thin portion.

5 is a diagram corresponding to FIG. 1 showing a conventional configuration.

FIG. 6 is a view corresponding to FIG. 1 showing a different conventional configuration.

[Explanation of symbols]

14 is a motor, 15 is an axial fan, 23 is a fan boss,
Reference numeral 24 is a blade, 24a is a peripheral portion on the tip side, and 25 is a thin portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yushi Hashimoto 4-21, Yoshihara-cho, Nishi-ku, Nagoya-shi Toshiba Corporation Nagoya factory

Claims (2)

[Claims] 1. An axial flow fan comprising a fan boss attached to a rotary shaft, wherein a plurality of blades are radially projected on an outer peripheral portion of a fan boss, wherein a thickness dimension is provided on a tip-side outer peripheral portion of each blade. An axial fan, which is characterized by forming a thin portion that is gradually smaller than other portions. 2. When the radial length from the base end of the blade to the outer peripheral edge is R and the width of the thin portion is t,
The axial fan according to claim 1, wherein the value of t / R is set to be within a range of 0.05 to 0.4.