JPS59196998A - Centrifugal multiblade fan - Google Patents

Abstract

PURPOSE:To reduce noise by a method wherein an annular body, having arced curved surface, is formed at the tip end part of the fan to form a smooth air introducing path by the annular body and a suction port having the shape of bell mouth. CONSTITUTION:The annular body 4a, having the curved surface of the shape of arc, is formed at the tip end of the fan 4. The smooth air introducing path is formed by the annular body 4a and the suction port 3d of the shape of bell mouth. According to this method, when air flows from the suction port 3d of the fan case 3 into the fan case 3, the flowing air passes the suction port 4c of the fan 4 smoothly without causing any turbulence as shown by arrow signs B and, then, flows into the fan case 3 through spaces between blades 4b. Accordingly, noise may be reduced remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a centrifugal multi-blade blower used in automobile air conditioners and the like.

In the conventional centrifugal multi-blade blower, when introducing air into the blower, turbulence of the air flow as shown by arrow A in FIG. 1 occurs.

That is, the air that has passed through the bellmouth-shaped intake port 2a is
A large number of blades 1 are sucked into the inside of the fan 1 through the suction port 1a of the centrifugal multi-blade blower fan 1 (hereinafter referred to as the fan), and the centrifugal force generated when the fan 1 rotates causes the blades 1 provided in large numbers to
It is released into the fan goo 2 from between the blade 1b and the blade 1b. At this time, the air that has once exited the fan 1 is sucked in again from the suction port 1a as shown by arrow AI, or collides with the upper plate 2a of the fan case 2 as shown by arrow A2. Disturbances occur and this causes noise.

Therefore, in view of the above points, the present invention improves the flow of air at the fan suction port by forming an introduction path that smoothly introduces air using the bellmouth-shaped suction port and the tip of the fan. The purpose is to significantly reduce the noise of centrifugal multi-blade blowers.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 2 is a top view showing an embodiment in which the centrifugal multi-blade blower of the present invention is applied to an automobile air conditioner, and FIG. 3 is a sectional view taken along line A-A in FIG. This is schematically indicated by arrow B. The fan case 3 is constructed by attaching an iron upper plate 3b forming the upper surface to a resin case 3a forming the side and lower surfaces in FIG. 3 by a known fixing method such as screwing (not shown).

This upper plate 3b has a cylindrical portion 3C having a certain appropriate height.
The tip of the cylindrical portion 3C is bent into a smooth arc inside the cylinder to form a bellmouth-shaped suction port 3d (hereinafter referred to as suction port). This intake port 3d
A resin centrifugal multi-blade fan 4 (hereinafter referred to as fan) is housed inside the fan case 3 at the bottom of the fan case 3. As shown in FIG. 2, this fan 4 has circular blades 4b formed at appropriate intervals, and as shown in FIG. It is integrally molded so as to be continuous with the blade 4b. In addition,
A circular suction port 4C surrounded by blades 4b is provided at the tip of the fan 4. This fan 4 is attached to the output shaft 5a by a known fixing technique such as screwing the connecting portion 4d. The fan motor 5 is attached to the fan case 3a via a flange 6 with screws 7 or the like. Further, the fan case 3 is provided with a connection port 3e for blowing out the air introduced into the fan case 3 from the suction port 03d to the downstream part.

Here, at the tip of the fan 4 facing the suction port 3d, a toric body 4a having an arcuate curved surface is provided as described below. In other words, the fan 4 is the blade 4b of the fan 4.
The tip of the blade 4b is integrally molded to have an arc shape, and the toric body 4a is heat welded to the tip of the blade 4b. At this time, as shown in FIG. 3, the circular arc portion of the side surface of the toric body 4a is arranged on a tangent to the bell mouth (circular arc) portion of the inlet 3d. Therefore, an air introduction path is formed inside the cylindrical portion 3c, which includes a bellmouth-shaped suction port 3d, a gap 8, and a toric body 4a. On the other hand, the radius of curvature R of the toric body 4a provided at the tip of the fan 4 is, for example, R=1 when the fan outer diameter D1 is I)+-140 mm.
The most desirable value is about 0111, and when R>12fi,
Pressure loss increases because the air ventilation area decreases.

Furthermore, if R<8 mm, the air flow will not be smooth and the effect will be reduced.

Further, the height H+ from the bottom surface of the fan case 3a to the joint 4e between the blade 4b and the torus 4a is the height H+ of the fan case 3a.
The height is set to be equal to or slightly lower than the height H2 from the lower surface of a to the upper plate 3b. In that case, the third
As shown in the figure, it is most preferable that G, H1, and H2 be equal.

Furthermore, the inner diameter D2 of the cylindrical portion 3C provided on the upper plate 3b is formed to be slightly larger than the fan outer diameter D.

Next, the operation of this embodiment having the above configuration will be explained.

When the centrifugal multi-blade blower of the present invention is applied to an automotive air conditioner, air taken in from outside the vehicle or from inside the vehicle flows into the fan case 3 from the intake port 3d as shown by arrow B in FIG. , is sent from the connection port 3e by the fan 3 driven by the fan motor 2 to the heat exchanger of the air conditioner (not shown) downstream, as shown by arrow C in FIG.

In the above air ventilation path, when air flows into the fan case 3 from the inlet 3d of the fan case 3, the incoming air flows into the bell mouth of the inlet 3d and the tip of the fan 4 as shown by arrow B. Since the air passes smoothly through the suction port 4C of the fan 4 without any disturbance along the arc of the provided toric body 4a and flows into the inside of the fan case 3 between the blades 4b, noise can be significantly reduced. .

FIG. 4 is a frequency analysis diagram showing the results of noise measurements conducted by the present inventors, where the horizontal axis shows the frequency and the vertical axis shows the sound pressure level of the noise. The measurements were made using a testing device that complies with JIS-B8330 r Blower Testing and Inspection Methods.
=10m, air volume 31zrrr/h, blower total pressure 28.2
It was done under Ryuhachiq's conditions. In FIG. 4, the solid line a indicates the conventional centrifugal multi-blade blower, and the broken line indicates the centrifugal multi-blade blower of the present invention.

As can be seen from this result, the frequency is, for example, 500 to 1
In the 000Hz range, noise is 3 to 5 dB lower than conventional
In the overall area, it is 2 times lower than before.
．． It has been found that the reduction can be achieved by 1 dB.

As described in the above embodiments, the present invention is very effective when applied to a centrifugal multi-blade blower for an automobile air conditioner. In other words, in recent years, as the quality of vehicles has improved, the demand for lower noise inside the vehicle interior has increased significantly, and the noise generated by the centrifugal multi-blade blower in the air conditioner is particularly loud, and the question is how to reduce this. This has become a problem.

Therefore, as described in the above embodiment, by applying the present invention, the flow of air flowing into the blower becomes smooth.
The noise generated by the blower can be significantly reduced.

It goes without saying that the present invention is not limited to centrifugal multi-blade blowers for automobile air conditioners, but can be effectively applied to all other centrifugal multi-blade blowers.

In addition, in the above embodiment, the toric body 4a provided at the fan tip cancer part may be integrally molded with the blade 4b, and then the other end of the blade may be connected to the connecting member 4d by heat welding or the like. . Moreover, the fan 4 and the toric body 4a are made of resin instead of
A suitable metal may also be used. Similarly, it goes without saying that the upper plate 3b of the fan case 3 may be made of resin instead of metal.

As described above, the present invention forms a torus having an arcuate curved surface at the tip of the fan, and smoothly introduces air through the bellmouth-shaped inlet provided in the fan case and the torus. By forming such an introduction path, the flow of air inside the centrifugal multi-blade blower becomes smooth, which has the effect of significantly reducing the noise generated by the centrifugal multi-blade blower.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional centrifugal multi-blade blower, FIG. 2 is a top view of the centrifugal multi-blade blower of the present invention, and FIG.
A sectional view and FIG. 4 are frequency analysis diagrams showing the noise measurement results of the conventional method and the present invention. 3...Fan case, 3d...Bellmouth-shaped inlet, 4...Centrifugal multi-blade fan, 4a...Circular/body. Representative Patent Attorney Takashi Okabe 1 Figure 2 627 Figure 3

Claims (1)

[Claims] In a blower including a centrifugal multi-blade fan that sucks air through a bellmouth-shaped suction port in a fan case, a ring having an arc-shaped curved surface is provided at a tip of the centrifugal multi-blade fan facing the bellmouth-shaped suction port. 1. A centrifugal multi-blade blower, characterized in that the toroidal body and the bellmouth-shaped suction port form a smooth air introduction path.