JP4657810B2 - Multi-blade impeller structure - Google Patents

Description

The present invention relates to a multi-blade impeller structure that can improve the efficiency and reduce noise of a small multi-blade fan used for cooling electronic devices.

  As shown in FIG. 11, the multiblade blower accommodates a multiblade impeller 102 in which a large number of blades 101 are arranged around a rotating shaft 100 in a scroll casing having an air suction port and a discharge port. The air blowing efficiency and noise greatly depend on the shape of the scroll casing and the shape of the wing 101. In particular, it is necessary to consider the angle formed by the blade center line called the inlet angle and the outlet angle of the blade 101 that greatly affects the air flow path in the impeller 102.

  FIGS. 14A, 14B, and 14C are general diagrams showing the shapes of the blades 110, 120, and 130 of the centrifugal impeller (Non-Patent Document 3). The entrance angle is the direction of the rotation direction. The angle formed from the inner diameter tangent A to the blade center line B is represented by β1 in FIGS. 14 (a), 14 (b), and 14 (c). On the other hand, the exit angle refers to the angle formed from the outer tangent C to the blade center line B in the direction of rotation, and corresponds to β2 in FIGS. 14 (a), 14 (b), and 14 (c). The entrance angle β1 and the exit angle β2 indicate the angle of a common location regardless of the shape of the wings 110, 120, and 130, and only their sizes change. That is, when the exit angle β2 is smaller than 90 degrees, the wing 110 faces rearward with respect to the rotation direction, and is called a rearward blade (FIG. 14A). The blade 120 having the same inlet angle β1 and outlet angle β2 is called a radial blade (FIG. 14B). On the other hand, when the exit angle β2 is larger than 90 degrees, the blades 130 face forward with respect to the rotation direction and are called forward blades (FIG. 14C), which is a multiblade impeller.

In Patent Document 1, as shown in FIG. 12, the entrance angle β1 is a complementary angle, that is, at an opposite position. In Patent Document 2, as shown in FIG. 13, the exit angle β2 is a complementary angle, that is, at the opposite position. Thus, there are two types of angles for specifying the blade shape, and it is necessary to define the angles in order to avoid misunderstandings.

Next, the optimum combination of the inlet angle β1 and the outlet angle β2, but as described above, in the multiblade fan, the pressure is increased by changing the direction of the air flow with the impeller, so that the rotation direction is originally reversed. When the air flow that flows into the blades in the direction flows out in the direction of rotation, the rotational energy of the impeller is most effectively given to the air flow, but in the actual air, flow separation occurs, etc. This is very different from the ideal state. Therefore, design values based on experiments are used for multiblade fans.
Patent Document 1 touches on an exit angle that is effective in improving air blowing efficiency and reducing noise. Patent Document 2 is characterized in that the entrance angle and the exit angle are different on the main plate side and the sub plate side, respectively.

  However, the entrance angle and the exit angle of Patent Document 1 shown in FIG. 12 and the entrance angle and the exit angle of Patent Document 2 shown in FIG. 13 are different from each other in the positions shown in the figure. I understand that.

Further, since the multi-blade blower increases the pressure by changing the direction of the air flow along the wing, the inlet angle and the outlet angle should be closely related to each other.
Japanese Patent No. 2667748 Japanese Patent No. 3507758 University lecture Fluid machinery, Oba, Kamiyama, Maruzen Co., Ltd.

However, in patent document 1, although the specific numerical value is shown about the exit angle, it does not touch about the entrance angle. On the other hand, Patent Document 2 states that the entrance angle is appropriately set in order to prevent a deviation from the airflow at the inlet portion of the blade, but the specific numerical values are not mentioned at all. . That is, even if an attempt is made to design a multi-blade impeller based on Patent Document 1 and Patent Document 2, information on a rough design policy can be obtained, but a specific index cannot be obtained, so it is not possible to rely on trial and error. It is difficult to achieve the objective of obtaining a multi-blade fan with high efficiency and low noise.
As described above, it is difficult to say that a multi-blade fan using a conventional multi-blade impeller has the best design in terms of both efficiency and noise. An impeller with high efficiency and low noise can be easily obtained. A design method is required. The optimal setting of the blade outlet suction surface side and the pressure surface side angle of Patent Document 1 and the optimal setting of the blade inlet angle and outlet angle in the axial direction of Patent Document 2 are the blade inlet angles. This is an effective improvement means after the exit angle is set optimally.

  The present invention solves the above-mentioned problems, and can easily design a multi-blade impeller for a multi-blade fan that has conventionally had to rely on experiments, and is a highly efficient and low-noise multi-blade impeller. An object of the present invention is to provide a multiblade impeller structure capable of obtaining the above.

In order to solve the above-mentioned problems, the present invention arranges a large number of wings on a common circumferential surface at regular intervals in the circumferential direction and along the axial direction, and one end of the multitude of wings is connected to the rotating shaft. And supporting the other end of the plurality of blades with an annular sub-plate so that air taken in from the suction ports of the annular sub-plate is ejected from the periphery of the multiple blades. In the multi-blade impeller structure, the angle formed by the tangent vector opposite to the rotational direction starting from the inner end point of the blade center line and the tangent vector of the outer blade center line starting from the inner end point of the blade center line. Is the entrance angle β1, and the angle formed by the tangent vector opposite to the rotation direction starting from the outer end point of the blade center line and the tangent vector of the blade center line outward starting from the outer end point of the blade center line is the exit angle. Enter β2 when the exit angle β2 is 140 degrees Multi-blade impeller structure corners .beta.1 86 degrees, or exit angle β2 which is characterized in that the set inlet angle .beta.1 to 67 degrees when the 160 degrees.

  As described above, in the multiblade fan using the multiblade impeller structure according to the present invention, both the airflow efficiency and the noise are good results, and the multiblade impeller of the multiblade fan that has conventionally had to rely on experiments According to the present invention, anyone can easily obtain a multi-blade impeller with high efficiency and low noise.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a perspective view of a multi-blade impeller according to the present invention, FIG. 2A is a perspective view of a multi-blade fan, and FIG. 2B is a perspective view showing a part of the multi-blade fan.
The overall configuration of the multiblade impeller and the multiblade blower of the present embodiment will be described with reference to FIGS. 1, 2A, and 2B.
In the multiblade impeller 1, a large number of blades 2 are arranged on a common circumferential surface at regular intervals in the circumferential direction and along the axial direction, and one end of the large number of blades 2 is connected to a rotating shaft. Is supported by the main plate 3 and the other ends of the multiple blades 2 are supported by the annular sub-plate 4. The multi-blade blower with the multi-blade impeller 1 assembled therein has the multi-blade impeller 1 built in a scroll casing 6 having a suction port 5a formed on the side wall. The multi-blade impeller 1 is rotationally driven by connecting the rotary shaft.
The multi-blade impeller 1 includes a plurality of blades 2 having shaft portions at both ends between a main plate 3 centered on a hub 7 joined to a rotating shaft of a motor and a sub-plate 4 positioned on the suction side of the multi-blade fan. When the motor rotates, the multiblade impeller 1 rotates and creates an airflow toward the outer periphery of the multiblade impeller 1.
The multi-blade impeller 1 is located at the scroll center of the scroll casing 6, and the air flowing from the suction port 5 a formed on the side surface of the scroll casing 6 by the rotation of the multi-blade impeller 1 Out of the multi-blade impeller 1 in the direction. Next, the air flow whose pressure has increased along the scroll casing 6 flows out of the discharge port 5b.

3A and 3B are plan views showing the shape of the blades of the multiblade impeller.
In FIG. 3A and FIG. 3B, when the air flow which flowed in from the inside of a multiblade impeller changes the direction of a flow with the wing | blade 2, a pressure rises. Thus, the change of the flow in the blade 2 is the air blowing principle of the multiblade fan, and therefore the inlet angle β1 and the outlet angle β2 of the blade 2 are important points in designing the multiblade fan.
That is, the tangent vector 9 of the circle passing through the inner end point 8 of the blade center line 16 opposite to the rotation direction starting from the inner end point 8 of the blade center line 16 and the impeller outward direction starting from the inner end point 8 of the blade center line 16 A circle passing through the outer end point 12 of the blade center line 16 and the angle 11 (entrance angle β1) formed with the tangent vector 10 of the blade center line 16 and the rotation direction starting from the outer end point 12 of the blade center line 16 The sum of the angle 15 (exit angle β2) formed by the blade center line tangent vector 14 starting from the outer end point 12 of the blade center line 16 and the blade center line tangent vector 14 facing the impeller is set in the range of 200 degrees to 240 degrees.

  Next, a method for obtaining the inlet angle β1 and the outlet angle β2 in the multiblade impeller structure of the present invention will be described. Trial manufacture of a multiblade impeller having various inlet angles β1 and outlet angles β2 The optimum inlet angle β1 and outlet angle β2 were obtained by replacing the impeller and measuring the blowing efficiency and noise.

As a result, as shown in FIGS. 4 and 5, it has been found that there is a combination that optimizes efficiency and noise in the entrance angle β1 and the exit angle β2.
In other words, FIG. 4 shows the maximum blowing efficiency of the impeller having 12 types of combinations of the outlet angle β2 of 140 degrees, 160 degrees, 170 degrees and the inlet angle β1 of 48 degrees, 67 degrees, 86 degrees, and 104 degrees, that is, the blowing output. Is the maximum value of the ratio of the shaft power and the inlet angle β1 and the outlet angle β2 are β1 = 48 degrees and β2 = 170 degrees, β1 = 67 degrees and β2 = 160 degrees, and β1 = It can be seen that the maximum efficiency is the largest when 86 degrees and β2 = 140 degrees. That is, it can be seen that the sum of the entrance angle β1 and the exit angle β2 becomes maximum at around 220 degrees. On the other hand, FIG. 5 shows the noise values of 12 types of impellers having the same combination of the entrance angle β1 and the exit angle β2, and the entrance angle β1 and the exit angle β2 are respectively represented by β1. = 48 degrees and β2 = 170 degrees, β1 = 67 degrees and β2 = 160 degrees, and β1 = 86 degrees and β2 = 140 degrees show that the noise level is the smallest. This is the same as the combination of the inlet angle β1 and the outlet angle β2 that maximizes the air blowing efficiency.
That is, it was found that the sum of the inlet angle β1 and the outlet angle β2 is around 220 degrees, and that the air blowing efficiency and noise are both optimal. A range where the sum of the inlet angle β1 and the outlet angle β2 is 220 degrees ± 12 degrees is an optimum state of both the blowing efficiency and noise. In this case, the exit angle β2 of the blade 2 is preferably in the range of 140 degrees to 170 degrees.
The entrance angle β1 and the exit angle β2 used in the experiment are based on the general definition described above.

FIG. 6 is a comparison of the air blowing efficiency and the noise level between the impellers having the optimum inlet angle β1 and outlet angle β2, and the air blowing efficiency is large when the outlet angle β2 is 170 degrees. At the same time, it can be seen that the noise level is also high. On the other hand, when the exit angle β2 is 140 degrees, the noise level is small as compared with other optimum combinations, but it is understood that the air blowing efficiency is somewhat inferior. That is, among the optimal combinations in which the sum of the entrance angle β1 and the exit angle β2 is around 220 degrees, when the exit angle β2 is set small, the design is focused on low noise, and when the exit angle β2 is set large. It can be seen that the design emphasizes efficiency. In addition, each is a combination in which the blowing efficiency and the noise are the best, and it goes without saying that both the efficiency and the noise are superior to those based on the conventional design.

Also, in the multiblade fan, the similarity law, that is, the characteristics of the fans having similar shapes of different sizes have a certain relationship with the size as a parameter, and therefore the inlet angle β1 and the outlet angle β2 of the present invention. Needless to say, this relationship is established regardless of the size of the impeller.

Next, in the multiblade blower shown in FIGS. 1 to 3, the conventional multiblade impeller and the multiblade impeller according to the present invention are accommodated, the flow rate and pressure characteristics are measured, and the blowing efficiency is calculated. And comparing the noise level at no load.
The outer diameter of the multiblade impeller is 95 mm, the number of blades is 23, and the blade thickness is 2 mm, which is the same as in the conventional example and the embodiment of the present invention.
As for the inlet angle β1 and the outlet angle β2 of the blade, as described above, there is no certain value because of the difference in the opinion of angle setting or the fact that it is set by experiment as described above. The angle β1 = 103 degrees and the exit angle β2 = 170 degrees. This is the conventional example shown in FIG.

On the other hand, in the Example which concerns on this invention, it measured about two types, the combination of entrance angle (beta) 1 = 67 degree and exit angle (beta) 2 = 160 degree, entrance angle (beta) 1 = 48 degree, and exit angle (beta) 2 = 170 degree. The sum of the entrance angle β1 and the exit angle β2 is 227 degrees and 218 degrees, respectively, as shown in the claims of the present invention, and is an angle that optimizes both blowing efficiency and noise.
After measuring the flow rate-pressure characteristics, the blowing efficiency is obtained from the ratio of the product of the flow rate and pressure and the shaft power. Next, the flow rate is converted into a flow coefficient φ using a dimensionless rule. The blowing efficiency becomes maximum when the flow rate is about 50% of the flow rate when the air flow is open, and it is most efficient to use this flow rate and pressure. Here, we decided to compare the maximum ventilation efficiency.

As for noise, a value obtained by measuring the noise under no load when the rotational speed of the multi-blade impeller is 2000 r / m with a microphone at a position 1 m from the suction port, and performing A characteristic correction which is a kind of auditory correction. We decided to compare.
FIG. 7 shows a comparison of the blowing efficiency of a conventional blade and a multi-blade fan having an inlet angle β1 = 67 degrees and an outlet angle β2 = 160 degrees of the embodiment of the present invention, and FIG. 8 similarly compares the noise characteristics. It is a thing. Although there is no significant difference in the air blowing efficiency, the noise of the example of the present invention is significantly reduced to 48.4 dB (A) compared to 51.4 dB (A) in the conventional example. I understand.

  Further, FIG. 9 is a comparison of the air blowing efficiency of a multiblade fan having an inlet angle β1 = 48 degrees and an outlet angle β2 = 170 degrees of the conventional example and the embodiment of the present invention, and FIG. Is a comparison. Regarding the noise, it can be seen that the embodiment of the present invention is reduced by about 1 dB, and the efficiency is greatly improved to 50.6% in the embodiment of the present invention compared to 48.1% in the conventional example.

  According to the above embodiment, in the multiblade fan using the multiblade impeller structure according to the present invention, both the air blowing efficiency and the noise are good results, and conventionally, many of the multiblade fans that have had to rely on experiments. The blade impeller design allows anyone to easily obtain a highly efficient and low noise multiblade impeller.

It is a perspective view which shows the multiblade impeller structure by embodiment of this invention. It is a perspective view of the multiblade fan provided with the multiblade impeller by embodiment of this invention. 1 is a partially cutaway perspective view of a multiblade fan equipped with a multiblade impeller according to an embodiment of the present invention. It is a top view which shows the multiblade impeller structure by embodiment of this invention. 3B is a partially enlarged view showing the multiblade impeller structure of FIG. 3A. FIG. It is a graph which shows the change of the ventilation efficiency by the entrance angle and exit angle of the multiblade impeller structure by embodiment of this invention. It is a graph which shows the change of the noise level by the entrance angle and exit angle of the multiblade impeller structure by embodiment of this invention. It is a graph which shows the ventilation efficiency and noise level of the multiblade fan which implemented this invention. It is a characteristic view which shows the comparison of the ventilation efficiency of the multiblade fan which incorporated the multiblade impeller of this invention, and the multiblade fan which applied the conventional multiblade impeller. It is a characteristic view which shows the comparison of the noise level of the multiblade fan which incorporated the multiblade impeller of this invention, and the multiblade fan which applied the conventional multiblade impeller. It is a characteristic view which shows the comparison of the ventilation efficiency of the multiblade fan which incorporated the multiblade impeller by other embodiment of this invention, and the multiblade fan which applied the conventional multiblade impeller. It is a characteristic view which shows the comparison of the noise level of the multiblade fan which incorporated the multiblade impeller by other embodiment of this invention, and the multiblade fan which applied the conventional multiblade impeller. It is a top view of the conventional multiblade impeller. It is a figure which shows the entrance angle and exit angle of the conventional multiblade impeller. It is a figure which shows the entrance angle and exit angle of the conventional multiblade impeller. (A) (b) (c) is a conceptual diagram which shows the example of the entrance angle of the conventional multiblade impeller, and an exit angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi-blade impeller 2 Blade 3 Main plate 4 Sub plate 5a Suction port 5b Discharge port 6 Scroll casing 7 Boss 8 Inner end point of blade center line 9 Inner diameter tangent vector opposite to impeller rotation direction starting from inner end point of blade center line 10 Blade tangent vector of impeller outward blade center line starting from inner end point of blade center line 12 Outer end point of blade center line 13 Outer diameter tangent vector opposite to impeller rotation direction starting from outer end point of blade center line 14 Blade center The tangent vector of the impeller outward blade center line starting from the outer edge of the line β1 inlet angle β2 outlet angle

Claims (1)

A large number of wings are arranged on the common circumferential surface at regular intervals in the circumferential direction and along the axial direction, and one end of each of the wings is supported by a main plate connected to a rotating shaft, In the multi-blade impeller structure in which the other end of a large number of blades is supported by an annular sub-plate, and the air taken in from the suction port of the annular sub-plate is ejected from the periphery of the numerous blades.
The angle formed between the tangent vector opposite to the rotational direction starting from the inner end point of the blade center line and the tangent vector of the blade center line outward starting from the inner end point of the blade center line is defined as an entrance angle β1, and the blade The angle formed by the tangential vector opposite to the rotational direction starting from the outer end point of the center line and the tangent vector of the blade center line outward starting from the outer end point of the blade center line is defined as the exit angle β2, and the exit angle β2 is 140. The multi-blade impeller structure is characterized in that the inlet angle β1 is set to 86 degrees when the angle is 60 degrees, or the inlet angle β1 is set to 67 degrees when the outlet angle β2 is 160 degrees .

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