JPH01159498A - Ventilating device - Google Patents

Abstract

PURPOSE:To suppress the ribs to make a load to the airflow at a minimum by inclining the ribs to fit the longest direction of the ribs of a protective guard to the inclining direction of the airflow passing through the ribs. CONSTITUTION:Concentric circle-form ribs 2a are formed making their installing angles to the airflow direction larger as they are in the outer circumferential direction. Radial-form ribs 2b are installed obliquely to the rotary direction of a fan. Consequently, the ribs are suppressed to make a load to the airflow at a minimum, making it possible to produce the largest airflow. Thereby, the noise is reduced extensively, and moreover, since they can be formed integrally with a bell mouth, the cost can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to an improvement in a protective guard for covering a blower of a blower device such as an air conditioner.

[Conventional technology]

A conventional blower device will be explained using figures.

Fig. 14 is a perspective view showing the external appearance of an air conditioner, which is a general blower, Fig. 15 is a cross-sectional view of the blower shown in Fig. 14, and Fig. 16 is a 60-year-old practical blower. -758
69 is a sectional view showing an air conditioner that is a conventional blower device and its blower; FIG.

In the figure, +11 is the outer box, (2I is the protective guard that covers the fan, +31 is the propeller fan that is the main part of the blower plate, (4) is the bell mouth, (5) is the motor that drives the propeller fan +31, (6) is a heat exchanger.

Although not shown in the drawings, a compressor, an electrical equipment box, a refrigerant circuit, etc. are installed on the negative side of the outer box +1) via a partition plate.

In the outdoor unit configured as above, the compressor is driven, and the propeller fan (5) is driven by the motor (5).
31 is rotated, outside air is sucked in from the air suction port (7) as shown in FIG.
) is discharged into the atmosphere from the air outlet 18) along the bell mouth (4) via the protective guard (2). This bell mouth (4) is curved outward on its suction side.
．． Since the shape is cylindrical and the blowout side 1 is cylindrical, the air flow direction of the propeller fan +31 is divided into the primary side and the secondary side, and the propeller fan (3) and bell mouth (4) apply pressure to the air. This results in a wind flow.

FIG. 11 and FIG. 18 are a sectional view and a front view showing the fan guard (2).

In the same figure, (2a) is a concentric lip, (2
b) is a radial rib, (2C) is a radial rib on the outer periphery.

(2d) is the center circle.

In addition to protecting the propeller fan +31, the protective guard (2) has the following functions: each rib (2a) to (2b).

There is a function to prevent children from getting injured by inserting their fingers into the propeller fan (3) that rotates nine times.

For this reason, there are restrictions on pitch and strength to prevent fingers from penetrating until they come into contact with the propeller fan. Furthermore, since the central circle (2d) corresponds to the hub of the propeller fan (3), it does little work as a blower, and a name plate with the company name, model name, etc. is pasted on it.

FIG. 19 is a cross-sectional view showing the radial rib (2C) in more detail at section B, B or section C, C of FIG. 18, where dbl, tbX, sbl are.

The width of the radial ribs (2b) or (2C), the pitch, and the minimum gap between the ribs.

Similarly, FIG. 20 is a cross-sectional view showing the concentric lip (2a) in more detail at cross section A, A, in FIG. 18, and *dal-tal*Sal is the width of the concentric lip (2a). , pitch, and the minimum gap between lips.

[Problem that the invention seeks to solve]

In conventional air blowers as mentioned above, protective guards (
2] is located downstream of the propeller fan 131.

Rather than the direct impact on the aerodynamic performance and noise level of the propeller fan +31 itself, the pressure loss and airflow noise of the protective guard (2 fan) are more problematic.

Generally, when air passes through a grid such as the protective guard (2), the flow is disturbed and airflow noise is generated.

Therefore, as one measure for reducing noise, a fan guard using wires may be used as shown in FIG. 21. This guard is made of thin metal wire coated with resin A3, reducing pressure loss to nearly half that of conventional plastic protective guards, and producing less airflow noise.

This is because, as shown in Fig. 22, in the case of the fan guard (2) using wire, the lip shape is circular.

Even if the incoming air enters diagonally, the radius dw of the rib does not change,
This is because the pitch tw of the ribs and the minimum gap SW also hardly change.

But in the case of protective guards with wire fiυ.

The cost is high, and unlike the conventional plastic protective guard, it cannot be integrally molded with the bell mouth (4), making it difficult to assemble. Furthermore, in terms of weather resistance, the above resin a was coated when exposed to the outside air for a long period of time.
There was a problem in that the Z peeled off and the appearance became shabby.

This invention was made to solve the above problems, and by reducing pressure loss and air flow noise,
The object is to provide a blower device with a protective guard that can significantly reduce noise.

[Means for solving problems]

In this invention, the longest direction of the cross section of the rib of the protective guard that covers the blower is inclined so as to match the inclination direction of the airflow passing through the rib.

[Function] In the blower device of this invention, the ribs of the protective guard are inclined to follow the flow of air.

It is possible to generate the maximum amount of air while minimizing the load on the air flow caused by the ribs, and it is also possible to significantly reduce noise.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

The external appearance of an air conditioner-like outdoor unit as a blower of the present invention and a cross-sectional view of the blower portion are the same as those in FIGS. 14 and 15, and therefore will be omitted.

1 and 2 are an enlarged sectional view and an enlarged front view of the protective guard (2). In the figure, (2a) is a concentric rib, (2b) is a radial rib, (2C) is a radial lip on the outer periphery, and (2d) is a center circle. Note that the arrow shown in FIG. 2 indicates the rotation direction of the fan.

As shown in FIG. 1, the mounting angle of the concentric lip (2a) with respect to the air flow direction (A in the figure) increases as it goes toward the outer circumference.

The radial lip (2b) is also attached diagonally in accordance with the rotational direction of the fan.

The pressure drop ΔP of a grid such as the protective guard (4) is
When a uniform flow flows perpendicularly to the grid, it can be predicted that the flow rate is approximately inversely proportional to the square of the flow rate Q, and that the proportionality constant ξ is also closely related to the aperture area AG of the grid.

ΔP = ξ Hakama Q2 + ξ = ft (Ac) However, in the case of the protective guard (2) located immediately after the propeller fan (3), the flow distribution and swirl flow depend on the blade shape and operating point of the propeller fan (3). are different, and due to the influence of these factors, the above-mentioned simple relationship cannot be established.Exactly the same can be said about airflow noise.

The above content will be explained in more detail. First, we will explain the mechanism by which swirling flow affects air volume and noise. Figure 3 is a diagram showing the rotation direction (arrow) of the propeller fan (3), where DH is the hub diameter of the propeller fan +31, and DB is the inner diameter of the bell mouth (4). ) swirling flow component of the air flowing out from (9
) is expressed as a vector. The wind speed increases as it goes toward the outer circumference, and the swirling flow component (9) flows obliquely into the radial lip (2b) of the fan guard. This will be described in detail in Fig. 5. Ingredients (9
If the angle between 1 and the radial lip (2C) is θ, then the first
The lip convergence db1 in Figure 9 increases to db2 (d
l) 1<db2) - The pitch tb+ of the lips becomes tb2 (tb+>tb2), resulting in the minimum gap between lips 5l) 1 becomes smaller than Sb2 (S
b1>5b2).

Such a mechanism increases pressure loss ΔP and airflow noise, leading to a decrease in air volume and an increase in noise.

This effect is large in the radial lip (2C) on the outer periphery because the wind speed of the inflowing air is high.
C Next, the effects of mixed flow components on air volume and noise will be explained. Figure 6 is a diagram showing the relationship between pressure P and wind JIQ, which shows the aerodynamic characteristics of the blower.

The operating point on the O side, that is, the open side, is shown in Figure 1.

The outflow velocity distribution becomes as shown, on the S side in Fig. 6.

In other words, at the operating point on the closing side, the outflow velocity distribution is as shown in FIG. Both flow out in the axial direction at the center, but the diagonal flow component molecule i[l increases toward the outer periphery. In addition, the diagonal flow component Q (1) at the outermost circumference is larger in FIG. 8 (S side in FIG. 6) than in FIG. 7 (0 side in FIG. 6). Circular rib (2a)
It flows diagonally into. This is shown in FIG. What is the mechanism by which the relationship between the mixed flow component a1 and the concentric lip (2a) affects the air volume and noise?

This is the same as the case of the swirling flow component (9) and the radial lip (2C), so it will be omitted.

Note that the angle between the mixed flow component a1 and the concentric lip (2a) is defined as ψ.

The results of υ analysis regarding the noise generated by the above protective guard (2:) are shown below.

First, when air flows vertically into the protective guard (2), the noise was expressed using each shape parameter as shown in the following equation, and it was confirmed that it matched with the actual measured value.

5PLA = ! , (Q, so, d, t)
[dBx) ...... (1) d: Rip width of the protective guard t: Rip pitch of 〃 (113) Furthermore, regarding the case where the air flow diagonally enters the grid as described above, the above il1 Extend the formula.

I created a formula like the following:

5PLA = ') 2 (Q* SQ* a, t*
θ) ・−・−・(1) θ: Room air blowout flow angle (degree) In this equation (II), the angle θ between the swirling flow component (9) and the radial lip (2C) is used.
Diagonal component + l [Angle ψ between l and concentric lip (2a)
can also be expressed as follows using the same idea.

5PLA= 'l 3 (Q+ sQ, a,
t, 9') ”...(Seal) Figure 10 shows an example of the calculation and measurement results for equation (1) for the swirling flow component 19).However, this result does not reflect the fan noise. The broken line in the figure is the calculated value for the conventional protective guard (2) when the outflow air flows perpendicularly to the protective guard (2), and the solid line is the swirling flow component (91 is the radial rib). This is a calculated value when considering the angle θ between (2C) and θ.This is a calculated value when considering the angle θ between
At an angle of =20U, the swirling flow component (9) has a radial lip (2C
). Therefore, the protective guard (2) was installed with the radial lip (2C) parallel to the swirling flow component 191, that is, at an angle of θ=20'.
were measured. (Mark C in the figure) - The result almost agreed with the calculated value (dashed line in the figure) when the outflow air flows vertically into the protective guard (2). As a result, noise levels were significantly reduced. Also, from other measurement results, in the case of general air conditioners, θ is 5 to 40 degrees.

It has been confirmed that ψ is in the range of 10 to 30 degrees.

From the above results, regarding radial lip (2b),
FIG. 11 shows a case where the radial lip (2b) is installed with an angle θ formed with the swirling flow component (9) of the incoming air. In the figure, the width db3 of the lip is the same as db+ in FIG. 18, and the pitch tb3 of the lip is Ab3=jbt.
The gap Sb3 between the ribs is 5bs=Sb1, which is the same as when the flow flows vertically into the protective guard (2) in FIG.

The concentric ribs (2a) are also shown in FIG. 12. The concentric lip (2a) is changed by ta5 = the angle ψ formed by the concentric lip (2a) and the oblique flow component Oe of the inflowing air.
By installing it at an angle with a pitch of tH+ /alIψ, the flow is the same as when it enters vertically as in the case of the radial lip (2b).

As mentioned above, in the above embodiments, radiation is used.

The concentric lip and the radial lip were installed diagonally so that they were parallel to the flow of air flowing out from the blower. In other words, the concentric lips are installed diagonally by the slope of the diagonal flow component of the air flowing out from the propeller fan, and the radial lips are installed diagonally by the slope of the swirling flow component of the air flowing out from the propeller fan. It is possible to generate the maximum amount of air while minimizing the load on the air, significantly reducing noise, and because it can be integrally molded with the bell mouth, costs can be reduced and mass production is possible.

By the way, in the above embodiment, the outer circumferential portion of the protective guard (2) has a radial lip (2c).

As shown in Figure 4, the swirling flow component in the outer layer is large;
Depending on the operating point of the blower, the value of θ of the above swirling flow component may be large (
However, the change in the mixed flow component ψ depending on the operating point is small. Therefore, in order to stably realize low noise, it is preferable to configure the outer peripheral portion to be mainly composed of concentric lips and reinforced with radial lips, as shown in FIG.

In the above embodiments, the cross-sectional shape of the lip is close to an oval shape such as an egg shape or a cylinder with one side rounded. (If the cross-sectional shape of the lip is elliptical, the long axis of the ellipse corresponds to the maximum length, and the short axis corresponds to the minimum length.) corresponds to

And the slope of the ellipse is the same as the slope of the long axis.

The slope of a lip whose cross section has a different maximum length and minimum length is the same as the slope of the maximum length or approximated by the slope of the maximum length.

〔Effect of the invention〕

As described above, according to the present invention, the lip of the protective guard is inclined so that the direction of the maximum length of the lip matches the inclination direction of the air flow passing through the lip, so that the lip becomes a load on the air flow. It is possible to generate the maximum air volume while minimizing the noise, and the noise can be significantly reduced.
It can be integrally molded with the bass mouse, and can be made of plastic, so it has the unique effect of being low cost and highly mass-producible.

[Brief explanation of the drawing]

Figures 1 and 2 are an enlarged sectional view and an enlarged front view of a protective guard according to an embodiment of the present invention, Figure 3 is a diagram showing the rotation direction of the propeller fan, and Figure 4 is a diagram showing the swirling flow components of the propeller fan. Figures 5, 11, and 19 are vector representations, sectional views of concentric ribs, Figure 6 are diagrams showing the aerodynamic characteristics of the blower, and Figures 7 and 8 are diagrams showing the air outflow velocity distribution. diagram showing,
Figure 9 and Figure 12 Figure 20 is a cross-sectional view of the radial rib, Figure 10 is a diagram showing calculated values and actual measured values of swirl flow components, Figure 13
14 is a perspective view of the blower, FIG. 15 is a sectional view of the blower, FIG. 16 is a sectional view of a conventional blower, and FIGS. 11 and 18 are A sectional view and an enlarged front view of a conventional fan guard. FIGS. 21 and 22 are cross-sectional views of the wire fan guard. In the figure, (2) is a protective guard, (2a) is a concentric rib, (2b) is a radial rib, (3) is a blower, (41 is a bell mouth, (5) is a fan motor, (6) is a
) indicates a heat exchanger;

Claims (3)

[Claims] (1) In a blower device equipped with a blower and a protective guard that covers the blower plate and consists of ribs whose cross-sections have different maximum and minimum lengths, the maximum length direction is aligned with the inclination direction of the airflow passing through the ribs. A blower device characterized in that the ribs are inclined so as to fit together. (2) The blower device according to claim 1, wherein the outer periphery of the rib is streamlined. (3) The air blowing device according to claim 1 or 2, wherein the cross section of the rib has a shape close to an ellipse.