JP2845247B2 - Push-in axial fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a push-type axial fan, which is disposed on the windward side of an engine cooling radiator mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, push-type axial fans as shown in FIGS. 15 and 16 have been known. These push-type axial fans 100 have a higher noise level as shown in FIG. 18, even if the fan blades 101 and 201 have the same shape, as compared with the suction-type axial fans 200 shown in FIG. FIG. 18 shows the results of the noise characteristics of the push-in axial fan 100 and the suction-type axial fan 200 at a rotation speed of 2000 rpm. In FIG. 18, the solid line Q indicates the push-in axial fan 100, and the broken line R indicates the suction-type axial fan 200.

The reason why the noise of the push-type axial fan 100 is large is presumed to be that the push-type axial fan 100 has a structure in which the flow is easily disturbed on the windward side of the fan. Therefore, attempts have been made to reduce fan noise by suppressing such disturbances.

FIGS. 19 and 20 show a known method of suppressing noise on the windward side of the fan blade 101 to reduce noise (Mitsubishi Heavy Industries technical report: V
ol. 24 (issued March 1987). In these prior arts, a suction ring 112 concentric with the rotation axis is arranged on the windward side of the fan blade 101 to rectify the windward flow.

However, in the push-type axial flow fan 100 as shown in FIGS. 19 and 20, the optimum shape of the suction ring 112 such as the diameter of the suction ring 112 and the shape of the front edge roundness is determined by changing the fan shape into various shapes. It was very difficult to find them in the blade 111 or in a wide ventilation resistance region. Further, in the push-in type axial fan 110, since the suction ring 112 is arranged on the windward side of the fan blade 111, that is, on the air passage, the suction ring 112 has a ventilation resistance. For this reason, in the push-in type axial fan 110, there was a problem that the blowing performance was reduced. Furthermore, the suction ring 11
2, there was a problem that noise such as wind noise was generated.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce noise in a push-type axial fan. Here, according to an experiment in which the present inventors visualized the flow of the push-in axial fan, FIG.
As shown in FIG. 1, a large wraparound flow was generated at the shroud edge portion 12, and it was confirmed that the sudden turning of the flow caused turbulence. Therefore, the present inventors have paid attention to the fact that this turbulence causes a decrease in air volume, noise deterioration, and the like.

On the other hand, according to an experiment in which the inflow portion 9 of the fan shroud 4 in FIG. 21 is removed and its flow is visualized,
As shown in FIG. 22, it was confirmed that a strong flow was generated from the outside in the radial direction to the inside at the tip portion 21 of the fan blade. Therefore, the present inventors have further studied the flow at the tip of the fan blade.

FIG. 23 shows models (1), (2) and (3) used by the present inventors for experiments. Inflow portions of the models (1), (2) and (3) are shown. Radii r ₁ , r ₂ ,
r ₃ is 80 mm, 40 mm, and 20 mm, respectively. Therefore, assuming that the length of the inflow portion of each model used in FIG. 23 in the axial direction is a, and the length of the inflow portion in the radial direction is b,
The dimensions of the model (1) are a = 80 mm and b = 80 mm. The dimensions of the model (2) are a = 40 mm, b = 40
mm. The dimensions of model (3) are a = 20 mm, b
= 20 mm. The graph of FIG. 24 shows the model (1),
The rotation speeds of (2) and (3) are displayed on the horizontal axis, and the noise level and air volume are displayed on the vertical axis. In the graph of FIG. 24, the solid line A indicates the model (1), the solid line B indicates the model (2), and the solid line C indicates the model (3).

From the graph of FIG. 24, the noise level and air volume of the push-in type axial fan can be determined by the models (1), (2),
It increases in the descending order of the radius r of the inflow portion of (3). Therefore, it can be seen that the bell mouth shape of the inflow portion has a good shape in which the windward end of the fan blade is opened to some extent. Therefore, as shown in FIG. 4, consider a bellmouth-shaped model (6) in which the windward end of the inflow portion is kept away from the fan blade in the radial direction with reference to the inflow portion of the model (5).

The graph of FIG. 25 shows the rotation speeds of the models (5) and (6) on the horizontal axis, and the noise level and air volume on the vertical axis. In the graph of FIG. 25, the solid line D indicates the model (5), and the solid line E indicates the model (6). From the graph of FIG. 25, there is no significant difference between the model (5) and the model (6) in the air volume per the same rotation speed. However, it can be seen that the noise level of the model (6) shows a significant noise reduction effect of 4 dB · A at 2000 rpm as compared with the measurement result of the model (5).

Next, the inventors of the present invention described the difference in the noise generation mechanism due to the difference in the bell mouth shape of the inflow section, as shown in FIG.
6 and the turbulence distribution diagram in FIG. Note that I indicates a disturbance degree of 0% to 20%, and I
I indicates a turbulence degree of 20% to 40%, and III indicates a turbulence degree of 40%.
% To 60%, IV indicates a degree of disturbance of 60% to 80%, and V indicates a degree of disturbance of 80% to 100%. The degree of these disturbances was calculated by the following equation.

[0012]

(Equation 5) Disturbance degree = 100 × ((U ² rms + V ² rms + W ² rms) / 3 (U ² + V ² + W ² )) ^1/2 U: Instantaneous velocity of air in radial direction of boss of push-in type axial fan V: Instantaneous velocity of air in circumferential direction of boss of push-in type axial flow W: Push-in axial flow Instantaneous velocity of air in the axial direction of fan boss U: Average velocity of air in the radial direction of the boss of the axial fan V: Average velocity of air in the circumferential direction of the boss of the push-in type axial fan W: Average velocity of air in the axial direction of the boss of the push-in type axial fan However, when U = V = W = 0, the degree of turbulence = 0. According to the graphs of FIGS. 26 and 27, the inflow portion is formed into a bell mouth shape in which the windward end of the fan blade is opened to some extent. However, it can be confirmed that a large disturbance component can be reduced.

In general, the generation of a vortex has been considered as a cause of noise deterioration. However, in a push-type axial fan in which a ventilation resistor such as a radiator is arranged on the leeward side of the fan blade, the pressure increases downstream of the fan blade, and the pressure increase at the leeward end of the fan blade is inevitably avoided. Absent. Therefore, as shown in the graphs of FIGS.
From the shroud model (8), which suppresses the generation of eddies and increases turbulence, the shroud model (9) which suppresses turbulence by smoothly discharging the vortex at the leeward end of the fan blade into the diffuser portion of the fan shroud. ) Can be confirmed to be better. Also, from the graphs of FIGS. 26 and 27, it is clear that the position where the generated eddy current and the cylindrical portion of the fan shroud interfere with each other greatly affects the noise level. Therefore, the present inventors proceeded with an experimental study on the extent to which the fogging allowance of the cylindrical portion affects the noise level.

FIG. 28 shows the models used by the present inventors in the experiments. Each model (10), (11),
The radii r ₁₀ , r ₁₁ , and r ₁₂ of the inflow portion of (12) are 80 mm, 40 mm, and 20 mm, respectively. K is the outer peripheral edge of the fan blade and the cylindrical portion 10 of the fan shroud.
And k ₁ is the cylindrical portion 10 of the fan shroud.
Is the length of That is, k ₁ −k = fogging allowance. The graph of FIG. 29 shows the relative position of the model (10) on the horizontal axis, and the noise level and air volume on the vertical axis. FIG.
The graph on the horizontal axis represents the relative position of the model (6) (FIG. 4),
The noise level and air volume are displayed on the vertical axis. In the graphs of FIGS. 29 and 30, the solid line F indicates the case of low resistance, that is, the case where only a single-tube radiator is arranged on the leeward side of the push-in axial fan, and the solid line G
Indicates a case of high resistance, that is, a case where a single-tube radiator and a refrigerant condenser are arranged on the leeward side of a push-in axial fan.

The present invention is based on the above-described experimental study on the push-type axial fan, based on which the flow from the outside to the inside in the radial direction of the fan flows smoothly into the tip of the fan blade to reduce the noise of the push-type axial fan. It was made to reduce it.

[0016]

SUMMARY OF THE INVENTION The present invention provides a fan blade for guiding air toward a leeward blown object, and a fan blade disposed to cover the fan blade and rectifying an air flow generated by the fan blade. In the push-type axial fan provided with a fan shroud to be performed, the shape of the fan shroud is determined based on the results of the above experimental study.

That is, the fan shroud has a cylindrical portion provided outside the plurality of fan blades, and an inflow portion extending from the windward end of the cylindrical portion toward the windward side. The protruding portion is opposed to the fan blade at a predetermined fogging margin at a downstream portion of the fan shroud end in the air flow direction. Also, the shape of the inflow portion is a shape that opens rapidly so that the radial length b of the inflow portion is larger than the axial length a of the inflow portion, and is radially inward from the outer peripheral side of the fan blade. Guide the incoming airflow.

[0018]

According to the structure of the present invention described above, the air flow generated by the rotation of the push-in type axial fan flows from the windward side of the fan shroud to the inflow portion and through the cylindrical portion to the leeward side of the fan shroud. In other words, by setting the radial length b to a large value, the generation of an airflow wrapping around the edge of the inflow portion is suppressed, and the inflow portion is formed to have a shape that is greatly opened in the radial direction, so that the airflow is formed inside the inflow portion. Allow it to flow into the tip of the fan blade without much contact with the wall. This allows
The airflow flowing around the edge is suppressed, and even when the airflow flowing around is generated, the airflow can be rectified and flown.

[0019]

According to the push-type axial flow fan of the present invention, the shape of the inflow portion on the windward side of the fan shroud is formed to be wider than a predetermined length in the radial direction, thereby suppressing the airflow flowing around the edge of the inflow portion of the fan shroud. In addition, since the inflow portion is made to have a suddenly widened shape, the airflow flowing around the edge is rectified and then flown into the tip of the fan blade, so that the fan which is strongly generated in the push-in type axial fan goes from the outside to the inside in the radial direction of the fan. It is possible to smoothly flow the air flow without obstructing it, and it is possible to suppress the generation of noise by suppressing the occurrence of turbulence in the air flow.

A push-type axial fan according to the present invention will be described with reference to an embodiment shown in FIGS. FIG. 1 is a model diagram used for describing the present embodiment, and FIGS.
FIG. 2 is a diagram showing an example of a push-in axial flow fan for a vehicle.
The push-in type axial fan 1 is composed of a plurality of fan blades 2, an electric motor 3 and a fan shroud 4, and is arranged on the windward side of a radiator 5 mounted on a vehicle.

The fan blade 2 is provided integrally on the outer periphery of the boss portion 6 and, when rotated, blows air so as to push air into the heat exchanger 5 arranged on the leeward side in the axial flow direction. The electric motor 3 is held by mounting stays 16 and 17 fixed to a fixing member (not shown) of the vehicle via a flange portion 15. The tip of the rotating shaft 8 is fixed to the center of the boss 6 by a fastener such as a bolt, and when energized, the fan blade 2 is rotated.

The fan shroud 4 includes an inflow section 9, a cylindrical section 10, and a diffuser section 11. The inflow portion 9 has a bell mouth shape, is arranged outside the plurality of fan blades 2, and extends from the windward end of the cylindrical portion 10 toward the windward side in the radial direction and the axial flow direction.
The inflow portion 9 functions to smoothly guide the air flowing into the fan shroud 4 from the open-air field, that is, the air flowing toward the heat exchanger 5.

The cylindrical portion 10 is disposed so as to cover the outer periphery of the fan blade 2, and does not impair the pressure difference between the positive pressure surface and the negative pressure surface generated by the fan blade 2. That is, it works to create an air flow to the heat exchanger 5. The diffuser portion 11 extends from the leeward end of the cylindrical portion 10 toward the leeward side in the axial flow direction, and the right end in the figure is fixed to the heat exchanger 5. The diffuser 11 functions to efficiently discharge the airflow to the leeward side in the axial flow direction.

Next, how the shapes and dimensions of the fan blade 2 and the fan shroud 4 are defined in the present invention will be described. First, in FIG. 1, the axial length of the tip portion 21 of the fan blade 2 is L = 4.
0 mm, the radius of the fan is R = 150 mm, and the axial length a of the inflow portion 9 of the fan shroud 4 and the radial length b of the inflow portion 9 of the fan shroud 4 are changed by changing b. How the characteristics change will be described.

FIG. 4 shows a conventional product (a = 20 mm, b = 10
FIG. 5 shows models (4), (5), (6), and (7) using the radial length b as a parameter on the basis of mm), and FIG. 5 shows models (4) and (5). , (6), and (7) at the same air volume, with the horizontal axis representing the radial length b. As shown in FIG. 5, when a is constant at 20 mm, the noise becomes smaller as the radial length b becomes larger up to a certain range, and particularly, the noise becomes sharply smaller when the radial direction b exceeds 10 mm.

FIG. 9 shows the degree of reduction of the noise level when the radial length b is changed while the ratio of the axial length a to the radial length b is constant (θ = constant). In this experiment, the radius of the fan 2 is R = 150 mm, and the reference noise level is the fan shroud shown in FIG. Therefore, according to FIG. 9, when R = 150 mm, b>
It is confirmed that 10 mm is sufficient. Here, it is determined that the fan blade radius R and the fan shroud shape are similar to each other, so that even if the diameter of the fan blade 2 is different, it is sufficient that 1/15 × R <b.

Next, a description will be given of the result of an experiment conducted on an appropriate condition of a which is another parameter for determining the bell mouth shape of the inflow section. As described above, the axial length a depends on the mutual relationship with the radial length b. Therefore, as shown in FIG. 6, the axial length a and the radial length b
FIG. 7 shows a comparison between the noise ratio and the air volume ratio with respect to the current product using the inflow angle θ as a parameter and the inflow angle θ of the shroud determined by the following equation. Conventional technology (θ <45 °, ie, a
It can be seen that noise is reduced when θ ≧ 45 °, that is, a <b with respect to <b), and that the air volume is increased. Here, it is understood that the minimum value of the axial length a is not particularly limited. The reason is that the performance is almost constant when θ> 70 °, but when θ> 90 ° or more,
This is because the performance is improved with respect to the conventional technology even when a <0. However, the minimum value of a is naturally defined by the restriction on the vehicle mounted state, that is, the distance from the heat exchanger as in b, and the range of a <3/4 × Lmm is practical.

The shape of the inflow portion 9 of this embodiment is set in the following range based on the above experimental results. When the axial length of the tip portion 21 of the fan blade is L = 40 mm and the radius of the fan is R = 150 mm, 10 mm <b,
Let b> a. In the present embodiment, the cross section of the inflow portion has a gentle arc shape. Further, as described above, the positional relationship between the fan blade 2 and the cylindrical portion 10 of the fan shroud 4 also greatly affects the noise level.

FIG. 8 shows (4) a = 20 mm, b = 10 m
m, (6) shows a model with a = 20 mm and b = 40 mm. K is the outer peripheral edge 2 of the fan blade.
1 and in the relative position of the cylindrical portion of the fan shroud, K ₁ is the length of the straight tubular cylindrical portion of the fan shroud, in the present embodiment is 15 mm. In FIG. 10, the inflow angle θ is set to 80 °, and the axial length L at the tip of the fan blade 2 is set to L.
The experimental results of examining the fluctuation of the noise level 11 by variously converting the ratio with the fogging allowance (k ₁ -k) are shown. The broken line H in the figure is b
= 0 mm, the solid line I indicates b = 10 mm, and the dashed line J indicates b = 20 mm. As is apparent from this data, it is desirable that the fogging ratio is 0.4 or more in order to exert the effect of the present invention. This is because a predetermined allowance is required to prevent air from flowing from the downstream side of the fan blade.

Next, FIG. 11 shows the performance change of noise and air flow when the fogging rate (K ₁ -K) / L of the straight cylindrical portion of the fan shroud is changed. If the fogging ratio is 0.3 or less, a backflow phenomenon occurs, and both noise and air volume deteriorate. When the fogging rate is 0.6 or more, the bell mouth-shaped inflow portion 9 of the present embodiment is used.
The effect of the above is reduced due to the obstruction of the flow by the straight pipe portion 10. Therefore, the fogging allowance K ₁ -K is larger than 0.3 L and smaller than 0.6 L (0.3 L <K ₁ <0.6 L).
Set to a range.

From the graphs of FIGS. 29 and 30, it is understood that the influence of the difference in the fan shroud shape and the relative position K on the air volume is small. On the other hand, the characteristics of the noise significantly change depending on the shape of the inflow portion 9 of the fan shroud and the difference in the relative position K. That is, it can be seen that the optimum matching point differs depending on the bell mouth shape of the fan shroud inflow portion.

In the case of the model (10), the difference in the position of the optimum matching point between the case of high resistance and the case of low resistance differs by about 40 mm. In addition, the noise level at the optimum relative position K is higher than that of the model (6). On the other hand, in the case of the model (6), since the difference in the position of the optimum matching point between the case of high resistance and the case of low resistance is about 10 mm, for example, K = −7.
If it is set to 5 mm, the push-in type axial fan has low noise at both low resistance and high resistance.

Here, the optimum range of the relative position K is -20.0 mm <K <-7.5 mm at high resistance and -5.0 mm <K <5.0 mm at low resistance. Note that the optimal range of the relative position K when mounted on a vehicle is −
10.0 mm <K <−5.0 mm is desirable.

As described above, the bell mouth shape of the inflow portion 9 of the fan shroud 4 is expanded in the radial direction and extended toward the windward side in the radial direction. The effect can be achieved. In this embodiment, the length in the axial flow direction at the tip of the fan blade 2 is L = 40 mm, and the radius of the fan is R = 15.
Although it was 0 mm, it may be other than this dimension. That is, the dimensions of each part can be freely changed as long as the bell mouth shape satisfies the relationship of a <b, 1/15 × R <b.

Next, in addition to studying the axial length a and the radial length b of the bell mouth-shaped inflow portion 9, a portion connecting the cylindrical portion 10 of the fan shroud 4 and the inflow portion 9 will be described. The radius of curvature r and the spacing (tip clearance) t between the fan shroud and the fan blade have been studied. This will be described below. In the examples so far, the chip clearance t was 3 mm.

FIG. 12 shows that a and b are representative of a = 20 mm and b = 40 mm in the range of the first embodiment.
A graph is shown in which the tip clearance t and the radius of curvature r are changed in the case of. In FIG. 12, the horizontal axis indicates the relative position K between the outer peripheral edge 23 of the fan blade and the cylindrical portion of the fan shroud, and these data are obtained when a radiator and a condenser are provided on the leeward side of the fan. 5 shows a measurement result when the engine is idling. In the figure, the dashed line K is the fan shroud of the model (4) in FIG. 4, the solid line L is t = 3 mm, r = 10 mm, the solid line M is t = 3 mm, r = 2 mm, and the solid line N is t = 6 mm, r = 6.
mm, the solid line O indicates t = 1.5 mm, r = 6 mm, and the solid line P indicates t = 3 mm, r = 6 mm.

FIGS. 13 and 14 show a more detailed relationship when K = 0. FIG. 13 shows the chip clearance t on the horizontal axis.
14 is a graph in which the vertical axis indicates the noise level, and FIG. 14 is a graph in which the horizontal axis indicates the radius of curvature r, and the vertical axis indicates the noise level. Here, the sound energy is very small,
Noise values fluctuate due to slight fluctuations in flow. For this reason, when the noise value changes by about 1 dB or more, the dominant difference of the noise amount may be reversed, but the change of the noise value less than this is within the range of the error due to the fluctuation of the flow. Has the same advantage. Therefore, 0.5 dB is selected as a critical point from the experience of the inventor, and t and r corresponding to this range are selected.
13 and FIG. 14 show that 4.5 mm ≦ r ≦
7.5 mm, 2 mm ≦ t ≦ 4 mm were obtained. According to the present embodiment, within this range, for example, t = 3 mm, R = 6 m
With m, a = 20 mm, b = 40 mm, and K = 0 mm, a noise reduction of 9 dB can be obtained as can be seen from FIG.

[Brief description of the drawings]

FIG. 1 is a model diagram used for describing an embodiment of the present invention.

FIG. 2 is a front view of the above embodiment.

FIG. 3 is a partial sectional view of the embodiment shown in FIG. 2;

FIG. 4 is a model diagram in which a radial length b is changed in the embodiment of the present invention.

5 is a graph showing a relationship between a radial length b and a noise level in each model of FIG. 4;

FIG. 6 is a model diagram showing an axial length a, a radial length b, and an inflow angle θ in the embodiment of the present invention.

FIG. 7 shows an axial length a in each model of FIG.
A graph showing a noise ratio and an air volume ratio when the radial length b and the inflow angle θ are changed.

FIG. 8 is a model diagram showing a typical example of an embodiment of the present invention.

FIG. 9 is a graph showing a relationship between noise levels when the radial length b is changed while the inflow angle θ is constant.

FIG. 10 is a graph showing a relationship between a fog rate, a noise level, and an air volume.

FIG. 11 is a graph showing a change in performance of noise and air flow when the fog rate is changed in the embodiment of the present invention.

FIG. 12 is a graph showing a noise level when the tip clearance t, the radius of curvature r, and the relative position K are changed in the embodiment of the present invention.

FIG. 13 is a graph showing a relationship between a tip clearance t and a noise level in the example of the present invention.

FIG. 14 is a graph showing a relationship between a radius of curvature r and a noise level in the example of the present invention.

FIG. 15 is a schematic view showing a conventional push-type axial fan.

FIG. 16 is a schematic diagram showing a conventional push-type axial fan.

FIG. 17 is a schematic diagram of an air flow in a conventional suction-type axial fan.

FIG. 18 is a graph showing noise characteristics of a conventional push-type axial fan and a suction-type axial fan.

FIG. 19 is a schematic diagram of air flow in a conventional push-type axial fan with a suction ring.

FIG. 20 is a schematic diagram of an air flow in a conventional push-type axial fan with a suction ring.

FIG. 21 is a schematic view of an air flow in a conventional push-type axial fan.

FIG. 22 is a schematic diagram of the air flow when the inflow portion of the fan shroud in FIG. 21 is removed.

FIG. 23 is a model diagram used for describing the present invention.

FIG. 24 is a graph showing a relationship between a noise level, an air volume, and a rotation speed.

FIG. 25 is a graph showing a relationship between a noise level, an air volume, and a rotation speed.

FIG. 26: Flow velocity vector diagram

FIG. 27 is a turbulent region distribution diagram.

FIG. 28 is a model diagram used for describing the present invention;

FIG. 29 is a graph showing the relationship between the noise level and the air volume and the relative position.

FIG. 30 is a graph showing the relationship between the relative position and the noise level and air volume.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Push-in axial fan 2 Fan blade 4 Fan shroud 9 Bell mouth-shaped inflow part 10 Cylindrical part

Claims (1)

(57) [Claims] A radiator disposed upstream of the vehicle radiator;
A fan that guides airflow toward this vehicle radiator
Blade and fan blade
And a fan shroud that rectifies the resulting airflow.
And the fan shroud includes a fan shroud tip and
Cylindrical part that opposes through a predetermined chip clearance
And is formed integrally on the air flow direction side of this cylindrical portion
The cylindrical portion has an air flow out of the tip of the fan blade.
Downstream of the fan blade and a predetermined
And the inflow portion has a radial length b larger than its axial length a.
The fan brake has a shape that opens so that
Guides the air flow from the outer periphery of
A push-in type axial fan.