JPH1193897A - Blade for air blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a noise, reduce a noise, and improve air blowing efficiency by forming a cross-sectional shape of blade plates in a streamline shape, and thickening it in order as it reaches the tip. SOLUTION: This blade 1 is constituted by installing plural blade plates 2 on an installing member 3 so as to be mountable/demountable. In the blade plates 2, a cross-sectional shape where the front end side of rotation is made thick is formed in a streamline shape, and a thickness is increased in order more than a thickness t1 of the base end as it reaches the tip, and a tip part is formed so as to become thick. It is installed at a rake angle as a whole, and an upper surface A may be a straight line, but a slight upward warp is desirably imparted as it reaches the downstream side. A tip part A is formed in the shape of advancing by a proper angle 8 more than a base end part and a central part C, and in an inside surface of a casing, a clearance 7 of a tip part front face is made larger than a clearance 6 of the tip part center (b). In this way, a pressure increase to the casing 5 by generation of a pressure wave in the tip part front face of the blade is prevented, and generation of a noise can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-volume, low-noise fan blade mainly used for a cooling tower or the like.

[0002]

2. Description of the Related Art FIG.
And FIG. The blower 50 includes a rotating blade 51,
It is mainly composed of a casing 52 for accommodating this, and a rotating blade drive motor 53. The drive motor 53 rotates a rotary main shaft 56 supported by a bearing 55 via a belt 54, and the blades 51 are detachably supported by a mounting member 57 mounted on the tip of the rotary main shaft 56 (in the example shown in the figure). (Four) blade plates 58 are attached, and each of the blade plates 58 is a flat plate or a streamlined cross section, and has an appropriate scoop angle.

[0003]

In the blade plate 56 having the above structure, the air scooped up by the rotation at an arbitrary point P on the blade in FIG. 4 does not flow in the circumferential direction Q, but is centrifuged. It flows in the outward R direction. Therefore, the air is compressed on the casing 52 side and is pushed up by the blades. For this reason, there is a problem that the air pressure decreases in the central portion, the air blowing efficiency decreases, and noise is generated. SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to prevent the generation of noise, to reduce noise, and to improve the blowing efficiency.

[0004]

According to a first aspect of the present invention, there is provided a blower blade having a plurality of blade plates centered on a rotating main shaft, each blade having a streamlined cross-sectional shape. In addition, it is characterized in that the thickness is gradually increased toward the tip.

[0005] The blade of the present invention having the above-mentioned structure has a streamlined cross-sectional shape and its wall thickness is gradually increased toward the tip, so that even if the generated wind is affected by the centrifugal force, it can be protected from the outside. It is pushed up in the circumferential direction without shifting to the direction.

A second invention is characterized in that the gap between the front surface of the tip portion and the casing is larger than the center of the tip portion.

The blade of the present invention having the above-described structure has a large gap between the front surface of the front end of the blade and the casing, so that the pressure wave at this portion is prevented from hitting the casing and noise is reduced. Reduction can be achieved.

According to a third aspect of the present invention, the blade plate is formed such that the front surface of the front end protrudes forward in the rotation direction from the base end and the center.

[0009] The blade plate of the present invention having the above-described structure scoops air at the tip of the blade rather than at the base and center of the blade plate to generate a flow of wind in the circumferential direction. It is possible to prevent the air that has been scooped up by the part and the central part from being biased in the outer peripheral direction due to the centrifugal force.

[0010]

1 to 3 show an embodiment of the present invention. This blade 1 has a plurality of (four in the illustrated example) blade plates 2,
2. . Is detachably attached to the attachment member 3. The mounting member 3 is mounted on the rotating main shaft 4 driven by the driving motor 53. Other components such as bearings are the same as those of the conventional example, and are not shown. Here, reference numeral 5 denotes a casing.

The blade plate 2 has a streamlined cross-sectional shape in which the front end side of the rotation is thick, and as shown in FIG. 3, the thickness gradually increases from the base end thickness t1 toward the front end. The tip portion has a thickness t2. Note that the entire surface is attached with a scooping angle α, and the upper surface A may be straight, but it is preferable to slightly warp upward toward the downstream side. Further, the distal end portion A has a shape advanced by an appropriate angle β from the base end portion B and the central portion C, and the gap 7 at the front surface of the distal end portion is larger than the gap 6 at the center portion b at the distal end. And This is to prevent the pressure on the casing 5 from increasing due to the generation of pressure waves on the front surface of the tip of the blade, and to reduce the generation of noise.

[0012] In the blade of the present invention having the above structure, the air scooped up at an arbitrary point C (the same point as the center part C in the drawing) with the rotation reaches the tip even when subjected to centrifugal force. The upper and lower surfaces of the blade plate are not displaced in the direction of the dotted line c as in the prior art, but are scooped in a substantially concentric d direction. Therefore, air can be pushed up over the entire surface of the blade,
Since the air to be scooped by the next blade is not biased to the outer periphery, the air can be efficiently pushed up in the entire blade.

At this time, when the distal end portion A is formed to have a shape advanced from the proximal end portion B, the wind scooped up by the distal end portion A causes the outer portion to be formed by the centrifugal force of the wind scooped up by the central portion and the proximal end portion. There is a further effect in preventing the bias toward the side.

[0014]

As described above, in the case of the present invention, the generation of noise is prevented by making the shape of the blade plate a streamlined shape, and the thickness is gradually increased as it reaches the tip. It is possible to prevent the air from being biased outward due to the centrifugal force of the air to be blown, and to improve the blowing efficiency. At this time, the blade plate is formed by projecting the front surface of the front end from the base end portion and the center portion, thereby forming an air layer flowing in the circumferential direction near the outer periphery of the blade, thereby forming the base end portion,
It is more effective to prevent the air flow from being biased outward due to the centrifugal force of the air flow generated by the central portion.

[Brief description of the drawings]

FIG. 1 is a plan view of a blower blade of the present invention.

FIG. 2 is a side view of the blower blade.

FIG. 3 is a sectional view taken along line XX in FIG.

FIG. 4 is a plan view of a conventional fan blade.

FIG. 5 is a longitudinal sectional view of the blower.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 blade for blower 2 blade plate 4 rotating spindle t1 base end wall thickness t2 front end wall thickness A front end B base end C central part a front end b front end center

Claims (3)

[Claims] 1. A blade for an air blower, comprising a plurality of blades centered on a rotating main shaft, each blade having a streamlined cross-sectional shape and being sequentially thicker as it reaches its tip. 2. The blade for a blower according to claim 1, wherein a gap between a front surface of the front end portion of the blade plate and the casing is larger than a center of the front end portion. 3. The blade for a blower according to claim 1, wherein the blade plate is formed by projecting a front surface of a distal end portion forward in a rotational direction from a base end portion and a central portion.