KR100663965B1 - Axial flow fan - Google Patents

Abstract

An axial flow fan is provided to reduce the noise when blasting and to improve the blowing performance by distributing the chord length as a three dimensional curved shape and maximize the sweeping, stagger, and camber angles. An axial flow fan(20) is composed of a hub(25) combined with a rotary shaft; and rotary wings radially arranged at the perimeter of the hub and integrally rotated with the hub to blow the air the shaft direction. Factors deciding shapes of the rotary wings are a chord length, a sweeping angle(a), a stagger angle, and a camber angle. The rotary wings have a first retardation interval whose chord length is gradually decreased from an inner end(32) to an outer end(33), an advancement interval continued to the first retardation interval, and a second retardation interval. The camber angle has a minimum when a length ratio(r/R) is 0.75~0.85.

Description

Axial flow fan

1 is an exploded perspective view of a typical axial fan assembly.

FIG. 2 is a front view of the axial fan shown in FIG. 1.

3 is a cross-sectional view taken along the line III-III of the axial fan rotor blade of FIG.

4 is a front view of an axial fan according to a preferred embodiment of the present invention.

5 is a cross-sectional view taken along line V-V of the rotary blade of the axial fan shown in FIG.

6 is a graph showing a change in the length of the chordal length with respect to the length ratio of the rotor blades of the axial fan shown in FIG.

7 is a graph showing a change in the sweep angle with respect to the length ratio of the rotor blade shown in FIG.

8 is a graph showing a change in installation angle with respect to the length ratio of the rotary blade shown in FIG.

9 is a graph showing a change in camber angle with respect to the length ratio of the rotor blade shown in FIG.

<Description of the symbols for the main parts of the drawings>

20 ... Axial fan 25 ... Hub

27.Center of hub 30.Rotating wing

32 ... inside edge 33 ... outside edge

34 ... Centerline 35 ... Perfect

36 ... Wonyeon W ... Ikhyeon Length

a1 ... Decrease section a2 ... Increase section

a3 ... 2nd reduction section α ... sweep angle

β ... mounting angle θ ... camber angle

60 ... band

The present invention relates to an axial fan including a hub coupled to a rotating shaft, and a plurality of rotary blades radially arranged on an outer circumference of the hub to blow air in an axial direction while being integrally rotated with the hub. By changing the shape of the rotary blade of the axial fan relates to an axial fan with high efficiency and a small amount of noise generated by the same driving force.

An axial flow fan has a plurality of rotary blades arranged radially around a hub, and is a fluid machine that blows air in the axial direction of a rotary blade while being rotated by a motor or the like. In order to promote heat dissipation of air-cooled heat exchangers such as radiators and condensers, a cooling fan that blows air for heat dissipation to the heat exchanger is a typical axial fan.

In general, as shown in Figure 1, the axial flow fan (1) is mounted in pairs with a shroud (2) that surrounds and secures its circumference and guides blowing air. As shown in FIG. 2, the axial fan 1 includes a hub 12 in the center and a plurality of rotary blades 11 radially arranged around the hub 12. A band 13 is provided at the outer end of the rotary blade. The axial fan 1 has a rotary blade 11 having a wired cross-sectional structure in which the hub 12 is coupled to the drive shaft of the drive motor 3 and is obliquely disposed on the hub 12 by the rotational force of the drive motor 3. ) Rotates integrally with the hub 12 to create a differential pressure according to the air flow speed difference on the front and rear surfaces to blow air in the axial direction.

In the configuration of such an axial fan, the fan is directly involved in the flow of air, and the rotor blade has a streamlined cross-sectional structure, and the air is driven from the front of the axial fan using the pressure rise of the pressure plane of the rotor blade according to the rotation. It draws in and pushes the air behind the axial fan.

Therefore, since the rotary blade 11 has the greatest influence on the blowing efficiency of the axial fan 1 and the amount of noise generated, as shown in the sectional view of the rotary blade of FIG. 3 showing the definition of the term related to the axial fan rotary blade. In the design of the axial fan 1, the chord length (W) of the rotor blade 11, the stagger angle (β), the camber angle (θ) and the front view of the axial fan of FIG. As shown in Fig. 2, the sweeping angle α is an important design factor.

There are many constraints when designing such an axial fan:

For example, automotive axial fans are used to cool radiators for engine cooling, condensers for air conditioners, or both, and must be able to generate sufficient airflow while overcoming the load on these heat exchangers. In addition, the blowing efficiency should be higher than the power consumption of the motor mounted on the hub, and the blowing noise should be small.

In constructing an axial fan capable of satisfying the above constraints, the blades of the axial fan have the greatest influence on the blowing efficiency and the amount of noise generated.

Accordingly, various methods have been proposed to improve the performance of the axial fan while satisfying the above constraints.

U.S. Patent No. 4,569,631 has a leading edge 17 having a certain amount of reverse sweep angle α in an area close to the hub and a radial sweep position in a region close to the band with a predetermined sweep angle above a certain value. An axial flow fan having an installation angle defined according to the present invention is proposed, and in US Patent No. 4,684,324, a median line 16 is defined as a combination of points circumferentially equidistant from the leading and trailing edges 18. Similarly to U.S. Patent No. 4,569,631, there is proposed an axial fan having a reverse sweep angle at the hub side and a forward sweep angle at the band side, and a blade length and an installation angle according to the position and radius changed from the backward direction to the forward direction. In addition, U.S. Patent No. 5,273,400 proposes a fan having a sweep angle that changes from rearward to forward direction from the hub side to the end, similar to the above two U.S. patents, and the blade length, installation angle, and camber angle are defined. In US Patent No. 5,393,199, the sweep angle of the rotor blade has a forward sweep angle from the hub side to the tip thereof, but the sweep angle at the tip of the rotor blade does not exceed 15 °, leading edge line (170) at the hub side (170). ) And a trailing edge line (180) has an area parallel to the radial line, and the axial fan increases and decreases as the blade length increases from the hub side to the wing tip.

In addition, the Republic of Korea Patent Publication No. 2000-0047976, 2001-0063068, 1999-0047379 and the like also discloses a technique for changing the design factors for the rotary blades of the axial flow fan to increase the blowing efficiency or reduce the noise.

However, the conventional axial flow fans as described above were able to obtain the effect of increasing the blowing efficiency or reducing the noise within a certain limit, but there was a certain limit.

Due to the flow characteristics of the axial fan, the flow from the band side and hub side of the rotor blades is concentrated in the mid-span of the rotor blades. , Or with a large installation angle or a large blade length, the load of the axial fan has an adverse effect on the overall efficiency by increasing the power consumption of the driving motor rather than the effect of the efficiency increase. There is a problem coming. In addition, as the demand level of the axial fan users increases, there is a problem that the noise of the axial fan should be increased while reducing the noise.

The present invention has been made to solve the problems described above, more specifically, noise generated by maintaining the optimum relationship between the blade length, sweep angle, installation angle, camber angle, etc. that determine the shape of the rotary blades While small, the blowing efficiency is aimed at providing a high axial flow fan.

In order to achieve the above object, the axial flow fan according to the present invention includes a hub coupled to a rotating shaft, and a plurality of rotations radially arranged on an outer circumference of the hub to rotate air integrally with the hub to blow air in the axial direction. The blade length includes a blade length, a sweep angle, an installation angle, and a camber angle as factors for determining the shape of the rotary blade, and the blade length is increased by a first decrease section between the inner and outer ends of the rotary blade. A section, a second reduction section, and a minimum value in the middle region of the rotary blades; The sweep angle is gradually changed from a negative angle to an outer end from the inner end of the rotary blade to a positive angle; The installation angle gradually decreases from the inner end to the outer end of the rotary blade, has a minimum value in the middle region, and increases toward the outer end; The camber angle is characterized by having a minimum at a point of 0.75 to 0.85 in length and gradually increasing from the point to the outer end of the rotor blade.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a plan view of an axial fan rotary blade according to a preferred embodiment of the present invention. 5 is a cross-sectional view taken along line V-V of the rotary blades of the axial fan shown in FIG. 4, and FIG. 6 is a graph showing the change in the length of the blade blade with respect to the length ratio of the rotary blades of the axial fan shown in FIG.

4 to 5, the axial fan 20 of the preferred embodiment of the present invention includes a hub 25, a rotary blade 30, and a band 60.

The hub 25 is installed to be rotatable about a rotating shaft by external power. The rotary blades 30 are radially arranged on the outer circumference of the hub 25 to blow air in the axial direction while being integrally rotated with the hub 25, and a plurality of rotary vanes 30 are provided. The portion where the rotary blade 30 and the hub 25 meet is called the inner end 32 of the rotary blade, the other end in the rotational radius direction of the rotary blade 30 is called the outer end 33.

The band 60 serves to complement the rigidity of the rotary blade 30, and is provided to rotate integrally with the rotary blade 30 on the outer end 33 of the rotary blade (30).

As the factors for determining the shape of the rotary blade 30, the blade length W, the sweep angle α, the installation angle β, and the camber angle θ are defined as described later.

In order to describe the factors for determining the shape of the rotary blade 30, the length ratio r / R is defined as the position coordinate along the rotation radius direction of the rotary blade 30. The length ratio r / R is the shortest straight length connecting the outer end 33 of the rotary blade from the inner end 32 of the rotary blade, that is, the total length R of the rotary blade as the denominator, and the inner end. It is a dimensionless value which is on the shortest straight line from (32), and made the molecular distance r of arbitrary points between the inner end 32 and the outer end 33 of the said rotary blade.

Referring to FIG. 5, the leading edge 35 is located at the uppermost end of the rotational direction in the cross section of the rotary blade 30, and is opposite to the leading edge 35, that is, in the direction of rotation of the vane. When a point located at the side end is called a trailing edge 36, a line connecting the respective points in the radial direction is connected to a leading edge line 350 and a trailing edge 360, respectively. line). In addition, the center line of the leading edge 350 and the trailing edge 360, that is, the line connecting the points located in the middle of the leading edge 35 and the trailing edge 36 positioned at the same radius in the rotary blade 30 is the centerline ( median line 34).

The chord length W is the distance from the leading edge 35 to the trailing edge 36, as shown in FIG. The blade length (W) is a factor representing the width of the rotation direction of the rotor blades 30 during the rotation of the axial fan 20, and affects the air volume and efficiency. That is, in the axial fan under the same conditions, the larger the length of the chord length (W) increases the air flow rate and efficiency, but rather decreases above a certain reference value. That is, due to the flow characteristics of the axial fan, a phenomenon in which the flow from the band 60 side and the hub side of the rotor blade is driven into the mid-span of the rotor blade occurs. In this case, if the length of the blade in the intermediate region is large, the axial fan ( Rather than having the effect of increasing the efficiency of 20), it is counterproductive from the load factor. Therefore, as shown in FIG. 6, in the preferred embodiment of the present invention, the blade length W of the rotary blade 30 is minimized in the middle region. In addition, the air volume and efficiency also vary depending on the distribution of the blade length (W) in the radial direction of the rotary blade (30). Therefore, in the preferred embodiment of the present invention, the chord length W is continuously changed in the form of a cubic curve while going from the inner end 32 to the outer end 33, and the first reduction section is bounded at each inflection point. (a1), an increase section (a2), and a second decrease section (a3) has a change distribution. The first reduction section a1 starts at the inner end of the rotary blade 30 to a point where the length ratio r / R becomes 0.5, and the chord length W has a minimum value at that position. In the first reduction section, the chord length W gradually decreases as the length ratio r / R increases. The increase section a2 is preferably connected to the first decrease section and has a length ratio r / R of 0.7 to 0.9. In the increase section (a2) as the length ratio (r / R) increases, the chord length (W) shows a gradually increasing distribution. The second reduction section a3 is connected to the increase section a2 and indicates a section up to the outer end 33. In the second reduction section a3, the length of the chord length W gradually decreases as the length ratio r / R increases.

6 shows a change in the length of the chord length W according to the radial position of the rotary blade 30 in the axial fan 20 according to the preferred embodiment of the present invention. In this graph, the vertical axis represents the dimensionless value obtained by dividing the blade length (W) by the rotation length (R). As can be seen in this graph, the axial flow fan 20 according to the present invention, the radial length from the inner end 32 of the rotary blade 30 toward the radial length W is the first decrease section, increase section, It can be seen that it is characteristically divided by the second reduction section. The distribution of the blade length W in the form of a tertiary curve is a feature of the present invention which is remarkably distinguished from the rotor blades of a conventional axial fan.

As shown in FIG. 5, the sweeping angle α is a straight line connecting the inner end 32 on the leading wire 350 of the rotary blade 30 at the hub center 27. An angle between Lo and a straight line Lr connecting an arbitrary point P on the leading wire 350 at the hub center 27. The angle refers to the angle of rotation (forward) of the wing as a positive (+) angle and the angle of the opposite direction of rotation (rear) to a negative (-).

The sweep angle α is optimized to reduce noise and improve efficiency. That is, as shown in FIG. 4, in the region close to the hub 25, the sweep angle α is reduced to compensate for the weakening of the wing strength which may occur due to the increase in efficiency and the sudden change of the sweep angle α at the hub side. In the region near the outer end 33 of the rotary blade 30, the sweep angle α was increased to reduce noise. More specifically, the sweep angle α has a negative angle at the inner end 32 of the rotary blade 30, and gradually decreases toward the outer end 33 of the wing, and then again in the rotational direction. Increases. As shown in FIG. 7, in the preferred embodiment of the present invention, the point at which the sweep angle α changes from a negative angle to a positive angle is a point at which the length ratio r / R becomes 0.8 to 0.9.

As illustrated in FIG. 5, the stagger angle β is an angle formed by a straight line connecting the leading edge 35 and the trailing edge 36 in the circumferential cross section of the blade with the rotational direction straight line HL. As the axial fan rotates, the air moves from the front of the rotary blade to the rear, and the movement of the air occurs as the rotary blade rotates to increase the pressure of the positive pressure unit 355. That is, as the axial fan rotates, a positive pressure (+) is generated at the positive pressure part 355 of the blade and a negative pressure (-) is generated at the negative pressure part 366, so that the positive pressure part 355 of the blade is required to rotate the axial fan. ) And a driving force of the motor that can overcome the pressure difference between the negative pressure portion 366. Paradoxically, it can be inferred that reducing the pressure difference between the positive pressure unit 355 and the negative pressure unit 366 reduces the rotational force required for the rotation of the axial fan and consequently improves the efficiency of the axial fan.

However, in the axial fan, if the mounting angle β is too large, peeling phenomenon occurs in the negative pressure portion 366, and the pressure difference between the two surfaces 355 and 366 becomes large, resulting in a sharp drop in efficiency. If it is too small, the high speed rotation is required to produce the required air volume, and the noise increases rapidly. Therefore, determining the appropriate installation angle β is important for improving the efficiency of the axial fan.

In addition, due to the flow characteristics of the axial fan, a phenomenon in which the flow from the band 60 and the hub side of the rotor blade is driven to the mid-span of the rotor blade occurs. In this case, when the installation angle β is large in the intermediate region, the axial flow Rather than bringing about an effect of increasing the efficiency of the fan 20, it is adversely affected by the load factor. Therefore, in the present invention, to have a minimum installation angle β in the middle region of the rotary blade (30).

In the axial fan according to the present invention, the mounting angle β of the blade is set at the outer end 33 of the rotary blade 30 of the axial fan 20 at the inner end 32. It is preferable to set it as 80%-95% of (), and it is preferable that the installation angle (beta) in the outer edge 33 is 15 degrees-35 degrees. In addition, in order to minimize the loss due to the load in the intermediate region of the rotary blade 30, the installation angle β is the minimum value at the point where the length ratio (r / R) of the rotary blade 30 is 0.4 to 0.6 It is desirable to have a. 8 shows the distribution of the installation angle β according to the preferred embodiment of the present invention according to the length ratio.

The camber angle θ is the angle between the tangent of the camber line 37 at the leading edge 35 and the tangent of the camber line 37 at the trailing edge 36 as shown in FIG. 5.

According to the preferred embodiment of the present invention, as shown in FIG. 9, the camber angle θ is gradually decreased from the inner end 32 of the rotary blade 30 so that the length ratio r / R is 0.75. At a point that is from 0.85 to an angle of 60% to 70% of the camber angle θ of the inner end 32, and gradually increases from that point.

  As described above, the shape of the rotary blade 30 of the axial fan 20 is determined by the blade length (W), the sweep angle (α), the installation angle (β), the camber angle (θ), the blade length (W) ) And the installation angle β have a minimum value in the middle region of the rotary blade, which is to minimize the load loss in the middle region of the rotary blade (30). The axial fan 20 can obtain the blowing efficiency and noise reduction effect required by the user when the combination of the design factors of the rotary blade 30 is optimal. The blowing efficiency of the axial fan 20 equipped with the rotary blade 30 according to the preferred embodiment of the present invention is superior to the blowing efficiency of the axial fan according to the prior art.

As mentioned above, although the present invention has been described with reference to preferred embodiments, the present invention is not limited to such an example, and various types of axial flow fans 20 can be embodied within the scope without departing from the technical spirit of the present invention. will be.

As described above, the axial flow fan according to the present invention improves the problems of the conventional axial flow fans, that is, a three-dimensional curve shape with respect to the radial direction of the rotation of the blade length, which is a factor that determines the shape of the rotary blade. By distributing to and maintaining the optimized relationship between the sweep angle, installation angle, and camber angle, the noise generated during blowing using the same power motor is small while blowing efficiency is high.

Claims (5)

A hub coupled to the rotating shaft, It is arranged radially on the outer periphery of the hub and comprises a plurality of rotary blades for blowing air in the axial direction while integrally rotating with the hub, the blade length, sweep angle, installation angle, as a factor for determining the shape of the rotary blades For axial fan with camber angle defined, The rotary blades are continuous in a first reduction section in which the blade length gradually decreases from an inner end to an outer end, in an increase section in which the blade length is gradually increased while the blade length is gradually increased. And a second reduction section in which the chord length gradually decreases, and has a minimum value in the middle region of the rotary blades; The sweep angle is gradually changed from a negative angle to an outer end from the inner end of the rotary blade to a positive angle; The installation angle gradually decreases from the inner end to the outer end of the rotary blade, has a minimum value in the middle region, and increases toward the outer end; The camber angle has a minimum value at a length ratio of 0.75 to 0.85, which is a ratio of an arbitrary point and the shortest length from the inner end of the rotary blade to the outer end direction with respect to the wing length which is the shortest length between the inner and outer ends of the rotary blade. Axial flow fan, characterized in that gradually increasing from the point to the outer end of the rotary blade. The method of claim 1, The first reduction section has a minimum value from the inner end of the rotary blade to the point of the length ratio of 0.5 and the length ratio of 0.5, the increase section is characterized in that up to the point of the 0.7 to 0.9 length ratio Axial fan The method of claim 1, And the sweep angle is changed from a negative angle to a positive angle at a point where the length ratio is 0.8 to 0.9 from the inner end of the rotary blade. The method of claim 1, The installation angle of the outer end of the rotary blade has a value of 80% to 95% of the installation angle of the inner end, the installation angle at the outer end is 15 ° to 35 °, the installation angle is the inner side of the rotary blade An axial flow fan having a minimum value at a point where the length ratio is 0.4 to 0.6 from the stage. The method of claim 1, The camber angle gradually decreases from the inner end of the rotary blade, and has a minimum value at an angle of 60% to 70% of the camber angle of the inner end at a point where the length ratio is 0.75 to 0.85, and gradually increases from that point. Axial flow fan.

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