JPH05126093A - Centrifugal fan - Google Patents

Abstract

PURPOSE:To provide a centrifugal fan which can increase gas volume and to sufficiently reduce noises. CONSTITUTION:A centrifugal fan is composed of a main shroud 31 and an auxiliary board 33 having a suction opening 33a connected by a plurarity of blades 35. A protrusion 37 extending in the width direction of the blade 35 is integrally formed on the surface 35a of the blade 35 against which the wind blows while the centrifugal fan is rotating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal fan which increases the air volume and suppresses the generation of noise.

[0002]

2. Description of the Related Art Generally, a centrifugal fan is known in which a main plate and an auxiliary plate having a suction port are connected by a plurality of blades (Japanese Utility Model Publication No. 61-21593).

In this type, air is sucked from the suction port when the centrifugal fan rotates, and this air is discharged to the outside from the outer edge of the blade through the ventilation passage formed between the main plate, the auxiliary plate and the blade. It is configured as follows.

[0004]

However, in the conventional structure, when air is discharged from the outer edge of the blade, the air discharged along the front surface of the blade and the air discharged along the back surface of the blade. Merge with each other in the vicinity of the outer edge of the blade, and this merge reduces the energy of the flow, reduces the air volume, and increases the noise.

Further, in this type of centrifugal fan, so-called NZ noise, which is so harsh to the user, is likely to be generated due to the fundamental frequency determined by the number of revolutions N and the number of blades Z, and a centrifugal fan capable of suppressing this noise is not yet available. There is a problem that it has not been proposed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to provide a centrifugal fan capable of increasing the air volume and sufficiently suppressing the generation of noise. is there.

[0007]

In order to achieve the above-mentioned object, the present invention provides a centrifugal fan in which a main plate and an auxiliary plate having a suction port are connected by a plurality of blades. It is characterized in that a protrusion extending in the width direction of the blade is provided on the surface of the blade on which wind blows when the fan rotates. Further, another invention is characterized in that the intervals between the adjacent blades are made unequal and the intervals between the facing blades are arranged at the same interval.

[0008]

According to the present invention, since the projections are provided on the surface of the blade of the centrifugal fan, the air discharged along the surface of the blade is discharged by riding on the projection. At the outer edge, it does not merge with the air discharged along the back surface of the blade, so that the energy of the flow is not consumed as compared with the conventional one, and the air volume is increased accordingly and the noise is suppressed. Be done. According to another aspect of the invention, the centrifugal fans are arranged such that the adjacent blades are arranged at unequal intervals and the facing blades are arranged at equal intervals. Does not collapse, and therefore the generation of noise due to this is suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows a state in which the ventilation makeup grill of the heat exchange unit is removed. In FIG. 2, reference numeral 1 denotes a unit body, and the unit body 1 is embedded in the ceiling 3. A centrifugal fan 5 is rotatably provided in the center of the unit main body 1, and an air passage 7 is formed around the centrifugal fan 5. A heat exchanger 9 having a substantially rectangular shape is arranged in the air passage 7 so as to surround the centrifugal fan 5. In addition, 11 is an exterior plate and 13 is a drain pump.

The linear portion 9a on the suction side of the heat exchanger 9 is also provided.
A control plate 21 extending inward, that is, extending to the centrifugal fan 5 side is attached to.

In this heat exchanging unit, the room air sucked from the central portion through the centrifugal fan 5 passes over the control plate 21 as shown in FIG. It flows out from the suction side of the exchanger 9 to the discharge side. At this time, since the control plate 21 has an appropriate resistance to the flow of air, the spaces A to D between the control plates 21 are controlled.
The internal pressure is made uniform, so that the generation of eddy currents in the spaces A to D, in particular, the generation of eddy currents at the corners 9c of the heat exchanger 9 is suppressed, and therefore, the generation of noise from the heat exchange unit. Is suppressed.

The control plate 21 is a linear portion 9a of the heat exchanger 9.
The positions are slightly deviated from the center of, and they are attached at positions where the mutual intervals are not equal. In the illustrated example, the control plate 21 at the end of the space A is mounted on the center line l ₁ of the centrifugal fan 5, and the control plate 21 at the end of the space B is mounted at a position separated from the center line l ₂ by α. The control plate 21 in the end of the space from the center line l ₁ to β
The control plate 21 at the end of the space D is attached at a position separated by γ from the center line l ₂ (where α>γ> β).

By the way, the centrifugal fan 5 constituting the essential part of this embodiment, as shown in FIG. 1, has a main plate 31 and a suction port 33a.
It is configured by connecting a plurality of blades 35 to the auxiliary plate 33 having the. And each feather 3
As is apparent from FIGS. 1 and 3, the outer edge of 5 is provided with a projection 37 that projects toward the surface 35a of the blade 35 and extends in the width direction of the blade 35. The projection 37 is preferably provided near the outer edge of the blade 35, not near the center of the blade 35 as shown in the drawing, and its cross-sectional shape is preferably a smooth arc.

However, according to this embodiment, when the centrifugal fan 5 is rotated to blow air, the air discharged at the outer edges of the blades 35 does not join. That is, FIG.
As indicated by A, the air discharged along the front surface 35a of the blade 35 is discharged while riding on the protrusion 37, and therefore does not join with the air discharged along the rear surface 35b thereof. Rather, they are emitted in a direction away from each other.

Therefore, as compared with the conventional one, the flow energy is not consumed, and the air volume is increased by that amount as shown in FIG. That is, according to this, when trying to maintain the same rotation speed, the air volume can be reliably increased. Further, according to this, when the centrifugal fan 5 rotates, its noise can be reduced as shown in FIG. That is, when trying to secure the same air volume, the noise level can be reliably reduced.

6 and 7 show measured values of noise, FIG. 6 shows measured values of the centrifugal fan 5 with the protrusion 37, and FIG. 7 shows measured values of the centrifugal fan 5 without the protrusion 37. There is. When compared with the case of FIG. 7, it was found that the NZ sound in the low frequency region a around 70 Hz, which is harsh in the case of FIG. 6, was greatly attenuated. As is apparent from this, according to the present embodiment, the protrusion 3 that protrudes toward the front surface side 35a of the blade 35 and extends in the width direction of the blade 35 is provided at the outer edge of the blade 35.
7 is provided, the airflow does not collide on the outlet side of the blades 35, and the effect of significantly reducing the noise of low frequency components can be obtained.

FIG. 8 shows another embodiment.

According to this, each blade of the centrifugal fan 5 has 4
The numbers 1 to 48 are attached, and the interval between the blades 41 to 48 is δ ₁
When δ ₈ is assigned, the distance between adjacent blades becomes unequal (i.e., δ ₁ ≠ δ ₂ , δ ₂ ≠ δ ₃ , δ
₃ ≠ δ ₄ , δ ₄ ≠ δ ₅ , δ ₅ ≠ δ ₆ , δ ₆ ≠ δ ₇ , δ ₇
≠ δ ₈ ), and so that the intervals between the facing blades are equal (ie, δ ₁ = δ ₅ , δ ₂ = δ ₆ , δ ₃ = δ ₇ , δ ₄
= Δ ₈ ), the blades 41 to 48 are arranged. When adjacent blades are arranged at unequal intervals, it is desirable to arrange them in order such that the intervals are large, small, large, and small. Specifically, when δ ₁ > δ ₂ , δ ₂ <
It is desirable to arrange them so that δ ₃ and δ ₃ > δ ₄ .

By the way, the fundamental frequency determined by the rotational speed N of the centrifugal fan 5 and the number Z of blades is N × Z / 60.
Although expressed in Hz, it is desirable to arrange the blades 41 to 48 at unequal intervals in order to attenuate the frequency that is an integral multiple of the fundamental frequency. However, if the centrifugal fans 5 are simply arranged at unequal intervals, the balance of the centrifugal fan 5 is lost, so that vibration and noise are generated.

Therefore, according to this embodiment, not only the adjacent blades of the centrifugal fan 5 are arranged so as not to be at equal intervals, but the facing blades are also arranged at equal intervals. Therefore, the balance of the centrifugal fan 5 is maintained, so that the generation of vibration and noise due to this can be surely suppressed.

The present invention has been described below based on an embodiment, but it is obvious that the present invention is not limited to this. For example, the shape of the protrusion 37 shown in FIG. 3 is not limited to that shape, and can be changed to various shapes.

[0023]

As is apparent from the above description, according to the present invention, the protrusion is provided on the surface of the blade, so that the air discharged along the surface of the blade rides on the protrusion. Since it is discharged, it does not merge with the air discharged along its back surface at the outer edge of the blade, so that the flow energy is not consumed as compared with the conventional one, and the air volume is increased accordingly. Noise can be reduced. According to another aspect of the invention, the intervals between the adjacent blades are made unequal, and the intervals between the opposing blades are arranged at equal intervals, so the balance of the centrifugal fan is not disturbed. Generation of noise can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a centrifugal fan according to the present invention.

FIG. 2 is a plan view showing an example of a heat exchange unit.

FIG. 3 is an explanatory diagram showing a main part of the present invention.

FIG. 4 is a diagram showing a relationship between air volume and rotation speed.

FIG. 5 is a diagram showing the relationship between air volume and noise.

FIG. 6 is a diagram showing measured values of noise.

FIG. 7 is a diagram showing measured values of noise.

FIG. 8 is a plan view showing another embodiment of the centrifugal fan.

[Explanation of symbols]

 1 Unit Main Body 3 Ceiling 5 Centrifugal Fan 7 Ventilation Path 9 Heat Exchanger 31 Main Plate 33 Auxiliary Plate 33a Suction Port 35, 41-48 Blades 35a Surface 37 Projection

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukio Aizawa 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (72) Inventor Takeshi Ogawa 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Denki Within the corporation

Claims (2)

[Claims] 1. A centrifugal fan comprising a main plate and an auxiliary plate having a suction port connected by a plurality of blades, wherein the surface of the blade on which the wind is blown when the centrifugal fan is rotated has a width direction of the blade. A centrifugal fan characterized by having a protrusion extending to the inside. 2. A centrifugal fan having a main plate and an auxiliary plate having a suction port connected by a plurality of blades, wherein the adjacent blades are arranged at unequal intervals and the blades facing each other are separated. A centrifugal fan characterized in that the intervals are arranged at equal intervals.