ES2731810T3 - Axial fan with blade leading edge that protrudes axially upstream of the hub and which includes a curvature (fold) as seen in a radial direction perpendicular to the radial extent of the blade - Google Patents

Abstract

An axial fan comprising: a hub (110), to which a central shaft (110a) is coupled; and a plurality of blades (120), coupled to the hub (110) in such a way that they rotate, in such a way that each of the blades comprises: a portion (121) for connection to the hub, which defines an inner end of the blade ( 120), such that the hub junction portion (121) is coupled to an outer circumferential surface portion of the hub (110); a tip (123), defining an outer end of the blade (120); a first wing portion (130), extending from the tip (123) in an inner radial direction; and a second wing part (140), extending from the first wing part (130) towards the hub (110), such that the first and second wing parts (130, 140) have been configured to form a slope with respect to a plane perpendicular to the central shaft, such that the hub (110) has a cylindrical shape, and the hub (110) comprises: a front surface portion (112), located facing a direction of download; a rear surface portion (114), facing an air blowing direction; and an outer circumferential surface part (113), which defines an outer circumference of the cylindrical shape, such that each blade comprises a delimiting part (135), which divides the first wing part (130) with respect to the second wing part (140), and each vane is bent by the boundary part such that the second wing part extends from the boundary part radially inward, more towards the front surface part of the hub than a virtual extension radially inward of the first wing part, from the delimiting part, such that each blade additionally comprises: a leading edge (125), defining a leading end according to the direction of rotation; and a trailing edge (126), defining a rear end according to the direction of rotation, such that the delimiting part (135) comprises: a first end (135a), formed at the trailing edge (126); and a second end (135b), formed at the leading edge (125), and so that the angle at which the blade is bent at the second end (135b) is greater than the angle at which the blade is bent at the first end (135a), and so that the pitch angle (b1, b2, b3) of each blade gradually increases from the tip towards the hub along the first wing part, the pitch angle being the angle of a part of the blade that extends like a chord, with respect to the plane perpendicular to the central shaft.

Description

DESCRIPTION

Axial fan with blade leading edge that protrudes axially upstream of the hub and which includes a curvature (fold) as seen in a radial direction perpendicular to the radial extent of the blade

BACKGROUND

The present invention relates to an axial fan.

In general, air conditioners are devices for cooling or heating an interior space. Such an air conditioner includes a compressor to compress a refrigerant, a condenser, in which the refrigerant discharged from the compressor is condensed, an expander, in which the refrigerant that passes through the condenser is expanded, and an evaporator, within the which the expanded refrigerant inside the expander is evaporated.

The condenser and evaporator of the air conditioner function as heat exchangers that carry out a heat exchange between the refrigerant and the outside air. The condenser and the evaporator are arranged inside an indoor unit or an outdoor unit. The heat exchanger disposed within the indoor unit is called the indoor heat exchanger, and the heat exchanger disposed within the outdoor unit is called the external heat exchanger.

Here, an axial fan for blowing air into the outdoor heat exchanger may have been arranged on one side of the outdoor heat exchanger that is disposed within the outdoor unit.

The axial fan includes a hub, connected to a rotating shaft of an engine, as well as a plurality of blades, coupled to the outside of the hub. When the axial fan is rotated by the motor drive, a pressure difference between the front and rear surfaces of the blades is generated. A suction force is generated due to the difference in pressures, which allows air to flow.

In this way, external air is sucked into the interior of the indoor unit by means of the suction force of the axial fan. Here, the external air passes through the heat exchanger arranged next to an air suction hole of the outdoor unit. Also, the external air is subjected to heat exchange with the refrigerant flowing into the heat exchanger, in order to allow the refrigerant to be condensed or evaporated, and then the external air is discharged to the outside of the unit. outside by the blowing operation of the axial fan.

Axial fans according to the related technique include a hub, coupled to a central shaft thereof, as well as a plurality of blades, coupled to an outer surface of the hub. The central shaft is coupled to a motor to rotate.

The cube has an approximately cylindrical shape. Also, the hub has a front surface part, which defines a front surface, a rear surface part, which defines a rear surface, and an outer circumferential surface part, to which the plurality of blades are coupled. Also, each of the blades includes a connecting part with the hub, which is coupled to the outer circumferential surface portion of the hub, and a tip, which defines an end of the blade.

In axial fans according to the related technique, the hub can have a relatively large diameter compared to the total diameter of the axial fan. For example, the hub may have a diameter between about 30% and about 35% of the total diameter of the axial fan. In this case, the axial fan may be impaired in its efficiency as a result of a phenomenon of flow separation, and noise may be generated.

That is, since the outer circumferential surface portion of the hub is arranged in a direction parallel to an air flow direction, friction with the air can be generated. In this way, the phenomenon of flow separation, or boundary layer detachment, occurs in the outer circumferential surface portion of the hub as a result of friction. In addition, a strong vortex is generated by the phenomenon of flow separation, and fan flow losses and loud noises are caused by the vortex. US 2,378,049 A discloses an axial flow fan with bent blades.

COMPENDIUM

The embodiments provide an axial fan that has improved fan efficiency and exhibits reduced flow noise.

According to the invention, an axial fan according to claim 1 is provided.

The first wing part extends into a first preset gradient starting from the tip. While extending from the first wing part to the hub, the second wing part has a second gradient preset

The second wing part may extend from the first end to the hub in a direction corresponding to the direction of extension of the first wing part, and be bent at a pre-established angle to extend from the second end according to the direction of extension of the first part of wing.

The bending angle from the first wing part to the second wing part may be around 0 ° at the first end, and may range between about 50 ° and about 70 ° at the second end.

The area of the portion in which the connecting part with the hub and the outer circumferential surface portion of the hub are coupled can be variable clockwise, or clockwise, or counterclockwise.

The connecting part with the hub may include: a leading end that extends along the leading surface portion of the hub; and a rear end that extends inclined with respect to the rear surface portion of the hub.

The distance between the front end and the rear end may gradually increase in the counterclockwise direction of the outer circumferential surface portion of the hub and gradually decrease in the clockwise direction of the outer circumferential surface portion of the hub.

A virtual circle (C) can be defined that joins the tips of the plurality of blades with each other, and the relationship between the radius (R2) of the virtual circle and the radius (R2) of the outer circumferential surface part, from the center of the cube, can range between about 10% and about 25%.

The first and second wing parts may be integrated with each other.

The first preset gradient and the second preset gradient may be different from each other. The axial fan may additionally include a central shaft, such that the angle between the outer wing part and the central shaft may be greater than that between the inner wing portion and the central shaft.

The details of one or more embodiments are set forth in the accompanying drawings and in the description given below. Other features will be apparent from the description and drawings, as well as from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a view of an outdoor unit according to an embodiment.

Figures 2 to 4 are views of an axial fan in accordance with one embodiment.

Figure 5 is a cross-sectional view taken along line I-I 'of Figure 2.

Figure 6 is a view of a connection part with the hub of a blade, in accordance with one embodiment. Figure 7 is a view of first and second blade portions of the blade according to one embodiment. Figures 8A to 8C are views illustrating the shape of an angle of passage of the blade when the second wing part has not been adopted in the blade.

Figures 9A to 9C are views illustrating the shape of a pitch angle of the blade when the second wing part has been adopted in the blade.

Figure 10 is a graph of the results obtained by comparing changes in the power consumption of the axial fan according to the related technique and of the axial fan according to one embodiment.

Figure 11 is a graph of the results obtained by comparing changes in axial fan noise according to the related technique and axial fan according to one embodiment. Figure 12 is a graphic view illustrating the vorticity, or generation of eddies, that occurs around the fan when the axial fan according to the related technique is operating.

Figure 13 is a graphic view illustrating the vorticity that occurs around the fan when the axial fan according to one embodiment is operating.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following of this report, embodiments provided by way of example will be described, with reference to the accompanying drawings. The invention may, however, be modified in many different ways and should not be construed as limited to the embodiments set forth herein; rather, alternative embodiments may fall within the scope of the present invention, which is defined by the appended claims.

Figure 1 is a view of an outdoor unit according to an embodiment.

Referring to Figure 1, an outdoor unit 10 of an air conditioner according to one embodiment includes a case 11, a heat exchanger 20, an axial fan 100, an engine, a compressor 40 and a lock plate 50. The locking plate 50 may have been arranged so that it divides the interior of the air conditioner into a space for electrical components, within which the compressor 40 is arranged, and a heat exchange space, within which the axial fan is arranged 100

An air suction part 15, into which external air is sucked in, and an air discharge part 16, through which the air subjected to heat exchange in the heat exchanger is disposed within the case 11 20 is downloaded. For example, the air suction part 15 may have been arranged on a rear surface part and on a side surface part of the box 11, and the air discharge part 16 may have been arranged on a front surface part of the box 11.

The heat exchanger 20 has been arranged inside the case 11, which allows the external air to be subjected to heat exchange with a refrigerant. The heat exchanger 20 may be folded from one side of the axial fan 100.

Figures 2 to 4 are views of the axial fan in accordance with one embodiment.

Referring to Figures 2 to 4, the axial fan 100 according to one embodiment includes a hub 110, arranged so that it is capable of being rotated by a central shaft 110a, and a plurality of blades 120, coupled to the outside of the hub 110. The central shaft 110a is coupled to the motor to rotate.

The hub 110 may have a cylindrical shape or a circular column shape. In detail, the hub 110 includes a front surface portion 112 defining a front surface of the hub 110, a rear surface portion 114 defining a rear surface of the hub 110, and an outer circumferential surface portion 113, defining a surface circumferential of the cylinder.

Here, the front surface or a front side of the hub 110 is facing a direction in which the air is discharged, and the rear surface or a rear side of the hub 110 is facing a direction in which the air it is blown, that is, a direction according to which the air is sucked. In the following, a description about the directions of the axial fan will also be set forth.

The blade 120 includes a first wing part 130 which extends with a first preset curvature (gradient), from the tip 123 towards the hub 110, and a second wing part 140, which extends with a second preset curvature (gradient) , from the first wing part 130 towards the hub 110.

The first and second preset curvatures are different from each other. In detail, an angle defined by the first wing part 130 and a central axis of the hub 110 may be greater than that defined by the second wing part 140 and the central axis of the hub 110.

A delimiter part 135 is defined between the first wing part 130 and the second wing part 140. That is, the delimiter part 135 can be a line that allows the first wing part 130 to be distinguished from the second wing part 140. The second wing part 140 may have a shape that bends quite sharply from the delimiter part 135 in the direction of the hub 110, that is, in the direction of the front surface portion 112 of the hub 110. Thus, the delimiter part 135 can be called "folded part".

The first wing part 130 may be referred to as "outer wing part", and the second wing part 140 may be referred to as "inner wing part". For example, the first and second wing parts, 130 and 140, can be integrated with each other.

The blade 120 includes a part 121 connecting with the hub, coupled to the outer circumferential surface portion 113 of the hub 110, as well as a tip 123 defining an end of the blade 120. The portion 121 joining with the hub defines an end inside of the blade 120, and the tip 123 defines an outer end of the blade 120.

The tip 123 is disposed at an outer end of the first wing part 130, and the connection part 121 with the hub is disposed at an inner end of the second wing part 140.

The blade 120 includes an leading edge 125, which defines a leading end according to a direction of rotation thereof, and an exit edge 126, which defines a trailing end according to the direction of rotation. In Figure 3, the axial fan 100 can rotate counterclockwise.

The blade 120 includes a pressure surface 127, facing an air discharge direction, and a negative pressure surface 128, facing an air blowing direction. The pressure surface 127 can be understood as a surface that is facing the front side to receive an air pressure, and the negative pressure surface 128 can be understood as a surface that is facing the side rear, as a surface opposite to the pressure surface 127.

When the tip 123 of each of the plurality of blades 120 is extended in a clockwise or counterclockwise direction, a virtual circle C can be defined. Reference is made to the distance from the center of the hub 110 or the central shaft 110a to the outer circumference of the virtual circle C, that is, the radius of the axial fan 100, such as R1. Likewise, reference is made to the distance from the center of the hub 110 or the central axis 110a to the outer circumference of the hub 110, that is, the radius of the hub 110, such as R2.

The hub 110 may have a relatively small size, compared to the total size of the axial fan 100.

In detail, the outer circumferential surface portion 113 of the hub 110 defines a side wall of a passage through which the air passes when the axial fan 100 rotates. The outer circumferential surface portion 113 of the hub 110 is parallel to an air flow direction, so that friction with the air is caused. In this way, a phenomenon of flow separation, or boundary layer detachment, can occur as a result of friction, so that the efficiency of the fan is impaired.

Thus, when the hub 110 has a relatively large size compared to the total size of the axial fan 100, a friction area can be increased. As a result, the air passage may have a small width, so that the performance of the axial fan 100 is impaired.

Therefore, in the present embodiment, the relative size of the hub 110 can be determined in such a way that the ratio between R2 and R1 is in the range between about 10% and about 25%. That is, compared to axial fans according to the related technique, the hub may have a relatively small size.

As described above, since the hub 110 has that relatively small size, the frictional force that occurs between the air flow and the hub 110 can be reduced. In this way, it is possible to avoid the generation of a vortex, in order to improve fan efficiency.

Figure 5 is a cross-sectional view, taken along the line I-I 'of Figure 2, and Figure 6 is a view of a part of union with the hub, belonging to a blade according to an embodiment.

Referring to Figures 5 to 6, the outer circumferential surface portion 113 of the hub 110 to which the central shaft 110a is coupled, and the plurality of blades 120 coupled to the outer circumferential surface portion 113, are coupled to the axial fan 100 according to an embodiment.

Each of the blades 120 includes a part 121 connecting with the hub, coupled to the outer circumferential surface portion 113 of the hub 110. The part 121 joining with the hub defines the inner end of the blade 120. A part to which the connecting part 121 is coupled with the hub and the outer circumferential surface part 113 of the hub 110, has an area that is variable along the outer circumferential surface part 113. That is, in Figure 6, the part to which a connecting part 121 with the hub and the outer circumferential surface part 113 of the hub 110 are coupled, has an area that gradually increases in an anti-clockwise direction and gradually decreases in a clockwise direction.

In detail, the hub connection portion 121 includes a front end 121a, disposed on one side of the front surface portion 112 of the hub 110, as well as a rear end 121b, disposed on one side of the rear surface portion 114 of the hub 110. In detail, the front end 121a may extend adjacent to the front surface portion 112 of the hub 110, and a rear end 121b may extend adjacent to the rear surface portion 114 of the hub 110. The front end 121a may be understood as a part facing the front of the connecting part 121 with the hub, and the rear end 121b can be understood as a part facing the rear of the connecting part 121 with the hub.

The front end 121a may extend approximately parallel along the outer circumferential surface of the front surface part 112, and the rear end 121b may extend inclined with respect to the rear surface part 114. Thus, The distance between the front and rear ends, 121a and 121b, can be gradually increased in a clockwise direction and gradually reduced in a counterclockwise direction, on the outer circumferential surface portion 113 of the hub 110.

As described above, the connecting part 121 with the hub may have a variable engagement area coupled to the outer circumferential surface portion 113 of the hub 110 in a clockwise or counterclockwise direction. In this way, the blade 120 can be stably coupled to the outer circumferential surface portion 113 of the hub 110.

Figure 7 is a view of the first wing part and the second wing part of a blade according to an embodiment.

Referring to Figure 7, the second wing part 140 according to one embodiment extends from the first wing part 130 towards the outer circumferential surface part 113 of the hub 110. Also, the second wing part 140 is bent in an address with respect to a center of the delimiter part 135.

Thus, with respect to a direction perpendicular to the central shaft 110a of the hub 110, the direction in which the first wing part 130 extends, that is, a curvature or gradient of the first wing part 130, may have been configured with a different shape from that of the second wing part 140, that is, a curvature or gradient of the second wing part 140.

In detail, the blade 120 includes an leading edge 125, which defines a leading end according to the direction of rotation, and an exit edge 126, which defines a trailing end according to the direction of rotation.

The leading edge 125 includes a first leading edge 125a, disposed in the first wing part 130, and a second leading edge 125b, arranged in the second wing part 140. Also, the leading edge 126 includes a first edge exit 126a, arranged in the first wing part 130, and a second exit edge 126b, arranged in the second wing part 140.

The first and second leading edges, 125a and 125b, as well as the first and second trailing edges, 126a and 126b, can be distinguished from each other with respect to the boundary part 135.

The second trailing edge 126b extends in a direction corresponding to a direction in which the first trailing edge 126a extends. That is, the second trailing edge 126b extends from the first trailing edge 126a to the hub 110, in a state in which the second trailing edge 126b is not bent.

In sum, it is understood that the angle at which the second wing part 140 bends from the first wing part 130, that is, a bend angle at a position where the delimiter part 135 contacts the edge rear output 126, is around 0 °. Here, the position in which the delimiter part 135 contacts the rear trailing edge 126 can be defined as a first end 135a.

On the other hand, the second leading edge 125b is bent in a predetermined direction with respect to the extension device of the first leading edge 125a, in its extension towards the hub 110. In Figure 7, the extension direction of the first leading edge of attack 125a is denoted by a virtual line la, and the extension direction of the second leading edge 125b has an established angle 01 with respect to line la.

That is, it is understood that the angle at which the first wing part 130 bends with respect to the second wing part 140, that is, the bend angle at a position where the delimiter part 135 contacts the edge of attack 125, is around 01. For example, the bend angle 01 may range between about 50 ° and about 70 °. Here, the position in which the delimiter part 135 contacts the leading leading edge 125 can be defined as a second end 135b.

In sum, while the blade 120 is not bent at the first end 135a of the delimiter part 135, the blade 120 may be bent to some extent at the second end 135b of the delimiter part 135. In other words, the angle at the that the second wing part 140 is bent with respect to the second end 135b, may be larger than that in which the second wing part 140 is bent with respect to the first end 135a.

As a result, the second wing portion 140 extends in a direction corresponding to the extension direction of the first wing portion 130 from the trailing edge 126. Moreover, the bending angle in the extension direction of the first wing part 130 may gradually increase towards the leading edge 125.

According to the constitutions described above, the blade 120 according to the present embodiment may have a large passage angle. In this way, the amount of air that is achieved by the rotation of the wings can be sufficiently ensured. This will be described later with reference to the accompanying drawings.

Figures 8A to 8C are views illustrating the shape of the blade angle when the second wing part has not been adopted in the blade, and Figures 9A to 9C are views illustrating the shape of the blade angle of passage when the second wing part has been adopted in the blade.

Figures 8A to 8C illustrate a state in which the pitch angle is gradually reduced towards the inside of the blade, that is, the hub, when the blade shape is adopted according to the related technique (a1>a2> a3) . Here, the angle of passage can be understood as an angle that forms a part of the blade with respect to a horizontal surface or horizontal line I1. Also, the horizontal surface or horizontal line can be understood as a surface or line that is perpendicular to the central axis of the cube.

In detail, Figure 8A illustrates a state in which the pitch angle of a blade tip is a1, and Figure 8B illustrates a condition in which the pitch angle defined in a radius position corresponding to approximately 70 % of the blade from the center of the cube, is a2. Here, the radius position of approximately 70% can be understood as a position corresponding to approximately 70% of a distance from the hub to the tip of the blade.

Also, Figure 8C illustrates a state in which the defined pitch angle in a radius position corresponding to approximately 40% of the blade 120 from the center of the hub, is a3.

The angles of step a1, a2 and a3 can be expressed by the following relational equation.

a1> a2> a3

That is, in the case of the blade shape in accordance with the related technique, the pitch angle is gradually reduced in the direction of the blade inside. In this case, since the blade's rotational force when acting on the air is lower, the fan performance may be impaired and the noise may increase.

Figures 9A to 9C illustrate a state in which the pitch angle gradually increases into the blade 120, that is, the hub, when the blade shape is adopted in accordance with the present embodiment.

Figure 9A illustrates a state in which the pitch angle of the tip 123 of the blade 120 is p1, and Figure 9B illustrates a condition in which the pitch angle defined in a radius position corresponding to approximately 70% of the blade 120 from the center of the hub 110, is p2. Also, Figure 9C illustrates a state in which the defined pitch angle in a radius position corresponding to approximately 40% of the blade 120 from the center of the hub 110, is p3.

The angles of step p1, p2 and p3 can be expressed by means of the following relational equation.

P1 <p2 <p3

That is, in the case of the blade shape according to the present embodiment, the angle of passage gradually increases towards the inside of the blade. In this case, since the rotational force of the blade when acting on the air is large, the fan performance can be improved and the noise can be reduced.

Figure 10 is a graph of the results obtained by comparing changes in power consumption of the axial fan according to the related technique and of the axial fan according to one embodiment, and Figure 11 is a graph of the results that they are obtained by comparing the changes in the axial fan noise according to the related technique and the axial fan according to one embodiment.

Referring to Figure 10, the amount of air is defined as the X axis, and the power consumption due to the operation of the axial fan is defined as the Y axis.

As the amount of air increases, power consumption tends to increase. It is also noted that the degree of increase in power consumption is smaller in the case of adopting the axial fan according to one embodiment, compared to the case of adopting the axial fan in accordance with the related technique. Therefore, when the axial fan according to one embodiment is in operation, the power consumption can be reduced compared to that of the axial fan according to the related technique.

Referring to Figure 11, the amount of air is defined as the X axis, and noise values caused by the operation of the axial fan are defined as the Y axis.

As the amount of air increases, noise values tend to increase. It is also noted that the degree of noise increase is smaller in the case of adopting the axial fan in accordance with one embodiment, compared to the case of adopting the axial fan in accordance with the related technique.

Therefore, when the axial fan according to the present invention is in operation, the noises can be reduced compared to the axial fan according to the related technique.

Figure 12 is a graphic view illustrating the vorticity, or generation of eddies, that occurs around the fan when the axial fan according to the related technique is in operation, and Figure 13 is a graphic view illustrating the vorticity which occurs around the fan when the axial fan is operating in accordance with one embodiment.

Referring to Figure 12, when the axial fan according to the related technique is operating, an unstable flow is generated, as shown by the reference symbol S1, that is, a strong vortex or swirl, by a separation phenomenon. of flow, or boundary layer detachment, due to the friction of the air around the hub 110.

In addition, it is observed that the unstable flow is generated on one side of the blade tip, due to the influence of the strong vortex, as shown by the reference symbol S1.

On the other hand, referring to Figure 13, when the axial fan according to the present embodiment is in operation, it is observed that the vorticity generated around the axial fan, that is, the hub 110 and the tip 123 of the blade 120 , is smaller compared to the case of Figure 12.

As described above, the axial fan according to the embodiments may have a relatively small cube height or diameter and include the first and second wing parts, in which the blades have different curves or gradients. In this way, it is possible to avoid the vortex that could occur around the fan.

According to the embodiments, since the hub has a relatively small height and diameter and the structure of the first and second blade portions of the blade has been improved, it is possible to improve the operating efficiency of the axial fan and the noise can be reduced flow.

Particularly, the second wing part, which has a different curvature from that of the first wing part, including the blade tip, may have been arranged inside the first wing part with respect to the delimiter part, as the center, and the second wing part may have been coupled to the hub. It is possible, therefore, to make the axial fan more compact to increase the area of air flow that passes through the outside of the hub. Also, the front end of the connection part with the hub disposed in the second wing part can be arranged adjacent to the front surface part of the hub, and the rear end of the connection part with the hub can be arranged inclined so such that the rear end is closer to the rear surface part of the hub. Therefore, even if the cube is reduced in height, the large pitch angle of the blade can be maintained.

Also, since the tube has a small size, the costs required for the manufacture of the hub can be reduced.

While embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that it is possible to contemplate numerous other modifications and embodiments by those skilled in the art, which fall within the scope of the invention, which It is defined by the accompanying claims.

Claims (10)

1. An axial fan comprising: a hub (110), to which a central shaft (110a) is coupled; Y a plurality of blades (120), coupled to the hub (110) so that they rotate, in such a way that each of the blades comprises: a part (121) connecting with the hub, which defines an inner end of the blade (120), such that the part (121) connecting with the hub is coupled to an outer circumferential surface portion of the hub (110) ; a tip (123), which defines an outer end of the blade (120); a first wing part (130), which extends from the tip (123) in an inner radial direction; and a second wing part (140), which extends from the first wing part (130) towards the hub (110), such that the first and second wing parts (130, 140) have been configured to form a slope with respect to a plane perpendicular to the central tree, so that the hub (110) has a cylindrical shape, and the hub (110) comprises: a front surface portion (112), facing a discharge direction; a rear surface portion (114), facing an air blowing direction; and an outer circumferential surface portion (113), which defines an outer circumference of the cylindrical shape, such that each blade comprises a delimiter part (135), which divides the first wing part (130) with respect to the second wing part (140), and each blade is folded by the delimiter part in such a way that the second wing part extends from the delimiter part radially inward, more towards the front surface part of the hub than a virtual extension radially into the first wing part , from the delimiting part, in such a way that each blade further comprises: a leading edge (125), which defines a leading end according to the direction of rotation; and an exit edge (126), which defines a rear end according to the direction of rotation, such that the delimiter part (135) comprises: a first end (135a), formed at the trailing edge (126); Y a second end (135b), formed on the leading edge (125), and so that the angle at which the blade is bent at the second end (135b) is greater than the angle at which the blade is bent at the first end (135a), and so that the angle of passage (p1, p2, p3) of each blade gradually increases from the tip to the hub along the first wing part, the angle of passage being the angle of a part of the blade that is extends as a rope, with respect to the plane perpendicular to the central tree. 2. The axial fan according to claim 1, wherein the second wing part (140) extends from the first end (135a) to the hub (110) in a direction corresponding to the extension direction of the first wing part (130) near the first end, and the blade is bent at a preset angle at the second end, such that the second wing part (140) extends from the second end (135b) towards the hub in the preset angle with respect to the direction of extension of the first wing part (130) near the second end. 3. The axial fan according to claim 2, wherein the angle between the first wing part (130) and the second wing part (140) is approximately 0 ° at the first end (135a), and oscillates substantially between 50 ° and 70 ° at the second end (135b). 4. The axial fan according to any one of claims 1 to 3, wherein the axial length of a part in which the connecting part (121) is coupled with the hub and the outer circumferential surface part (113 ) of the cube (110), is variable in a clockwise or counterclockwise direction. 5. The axial fan according to claim 4, wherein the part (121) connecting with the hub comprises: a front end (121a), which extends adjacent to the front surface portion of the hub (110); and a rear end (121b), which extends inclined with respect to the rear surface portion of the hub (110). 6. The axial fan according to claim 5, wherein the plurality of blades rotate in a counterclockwise direction; Y in which the distance between the front end (121a) and the rear end (121b) gradually increases in the counterclockwise direction of the outer circumferential surface part (113) of the hub (110) and gradually decreases in the clockwise direction of the part of the outer circumferential surface (113) of the hub (110). 7. The axial fan according to any one of claims 1 to 6, wherein a virtual circle (C) linking the tips (123) of the plurality of blades (120) to each other is defined, and a relationship between a radius (R1) of the virtual circle and a radius (R2) of the outer circumferential surface portion (113), from the center of the hub (110), ranges from about 10% to about 25%. 8. The axial fan according to any one of claims 1 to 7, wherein the first and second wing portions (130, 140) are integrated with each other. 9. The axial fan according to any one of claims 1 to 8, wherein the angle at which the first wing part (130) is inclined with respect to the plane perpendicular to the central shaft, is different from the angle with the that the second wing part (140) is inclined with respect to the plane perpendicular to the central tree. 10. The axial fan according to claim 9, wherein the angle at which the first wing part (130) is inclined with respect to an axial direction of the central shaft (110a), is greater than the angle with the that the second wing part (140) is inclined with respect to an axial direction of the central shaft (110a).