Patent Description:
A blower circulates air in an interior space or generates airflow toward a user by generating flow of air. When a blower has a filter, the blower can improve the quality of interior air by purifying contaminated air in the interior.

A fan assembly that suctions air and blows the suctioned air to the outside of the blower is disposed in the blower.

The region to which air is discharged from the blower extends in the up-down direction to supply much purified air to an interior space.

However, there is a problem in the related art in that a fan assembly cannot generate uniform rising airflow with respect to air suctioned from under, so purified air is not uniformly supplied to a discharge region extending up and down.

Further, there is a problem in that blower performance is deteriorated and excessive noise is generated due to friction with and flow separation from an internal structure of the blower in the process of generating rising airflow.

A mixed-flow fan that is mounted on an air conditioner has been disclosed in <CIT>, but a way of generating upward airflow through the mixed-flow fan is not provided, so there is a problem in that the up-down length of a discharge region is limited.

A fan assembly that discharges air forward through Coanda effect has been disclosed in <CIT>, but a structure that suppresses vortex generation and flow separation in the process of forming upward airflow is not provided, so there is a problem in that excessive noise is generated. <CIT> relates to a blower fan in which a flow direction of air is changed and an air conditioner including the same. <CIT> relates to impellers for producing movement of a gaseous fluid and apparatus incorporating such impellers.

An object of the present disclosure is to provide a blower that changes air discharged from a fan into ascending airflow and supplies the ascending airflow to a tower.

Another object of the present disclosure is to provide a blower in which noise is less generated.

Another object of the present disclosure is to provide a blower in which the flow rate of air that is discharged fro the fan and is lost is reduced.

Another object of the present disclosure is to provide a blower having a diffuser that guides a flow direction of air discharged from a fan.

Another object of the present disclosure is to provide a blower having a diffuser of which the shape change is minimized.

The objectives of the present disclosure are not limited to the objects described above and other objects will be clearly understood by those skilled in the art from the following description.

In order to achieve the objects, a blower according to an embodiment of the present disclosure includes: a lower case in which a suction hole through which air flows inside is formed; and an upper case that is disposed on the lower case and in which a discharge hole through which air is discharged is formed.

The blower includes a fan motor that provides rotational force and a fan that is disposed in the lower case and is fixed to a motor shaft of the fan motor, so it is possible to supply inflow air to the upper case.

The fan includes a hub having an outer surface extending to be inclined at a first angle with respect to the motor shaft, a plurality of blades coupled to the hub, and a shroud extending to be inclined at a second angle, which is larger than the first angle, with respect to the motor shaft and having an inner surface facing the outer surface of the hub with the blade therebetween, so it is possible to minimize a loss of flow rate due to the difference of the inclination angles of the hub and the shroud.

The hub forms a hub upper end by extending outward in a radial direction and the shroud may form a shroud edge by extending outward in a radial direction.

The shroud edge is positioned outside further than the hub upper end in the radial direction, so it is possible to prevent a phenomenon in which air comes out of the shroud.

The rim portion is positioned outside in a radial direction further than a hub upper portion, so air passing through the rim portion can be guided upward by the hub.

The hub may include: a shaft coupling portion that protrudes up and down at a center of the hub and in which the motor shaft is inserted; a first inclined surface extending outward from the shaft coupling portion; and a second inclined surface extending to be inclined outward from the first inclined surface.

The shaft coupling portion may form a hub lower end by protruding downward from the center of the hub and may form a hub protruding portion by protruding upward.

The shroud edge may be positioned at a height between the hub lower end and the hub protruding portion.

The shroud edge may be positioned at a height between a hub lower end and the first guide surface, so air flowing inside through the shroud can flow upward over the first guide surface.

The shroud includes a rim portion upper end connecting the rim portion and the supporting portion.

The shaft coupling portion may be positioned higher than the rim portion upper end, so air passing through the rim portion can be guided to the first guide surface.

The shroud inclination angle may be formed in a range of <NUM> degrees to <NUM> degrees.

An expansion angle may be formed between the hub and the shroud, so air flowing through the shroud can be smoothly pressurized by the blades.

The expansion angle may be formed within a range of <NUM> degrees and <NUM> degrees.

A blower according to an embodiment of the present disclosure includes a diffuser that is disposed at a downstream side of the fan and extends in an up-down direction, so it is possible to change the flow direction of air discharged from the fan into ascending airflow.

The diffuser includes a lower end that is concave upward, so air reaching the diffuser can be guided to a diffuser surface over the lower end formed to be concave.

The blower includes: : a fan housing in which the fan is accommodated; and a motor housing in which a fan motor applying power to the fan is accommodated.

The diffuser is disposed between the fan housing and the motor housing, so the diffuser can be supported by the fan housing and the motor housing.

The diffuser may extend to be curved in an up-down direction, so it is possible to have adaptation to a flow direction.

The diffuser may include: a first extending portion extending to be curved downward from an upper end; a second extending portion extending upward from the lower end; and a bending portion connecting the first extending portion and the second extending portion.

At least a portion of the diffuser may be positioned between the hub and the shroud in a radial direction, so air discharged between the hub and the shroud can flow toward the diffuser.

A height of a lower end formed to be concave from an upper side may be formed within a range of <NUM>% to <NUM>% of an entire height of the diffuser, so it is possible to reduce flow friction by a lower edge.

The diffuser may have a plurality of diffuser grooves extending in an up-down direction and spaced apart from each other in an extension direction of the lower end, to air flowing to the diffuser can flow upward.

A rib may be formed between the plurality of diffuser grooves.

A groove lower end of the diffuser groove may be formed to come in contact with a lower end of the diffuser, so air reaching the groove lower end of the diffuser groove can flow upward over the diffuser groove.

A groove upper end of the diffuser groove may be formed to be spaced apart from an upper end of the diffuser, so it is possible to reduce flow friction that is generated at the upper end of the diffuser.

Groove upper ends of the plurality of diffuser grooves may be positioned on the same horizontal surface.

The details of other exemplary embodiments are included in the following detailed description and the accompanying drawings.

According to the blower of the present disclosure, one or more effects can be achieved as follows.

First, since the expansion angle is formed between the hub and the shroud and the diffuser is disposed at a downstream side of the fan, there is an advantage in that it is possible to change the air discharged from the fan into ascending airflow.

Second, since the expansion angle is formed between the hub and the shroud and the lower end of the diffuser is formed in an arc shape, there is also an advantage in that it is possible to reduce noise by decreasing flow friction.

Third, since the expansion angle is formed between the hub and the shroud and the lower end of the diffuser is formed in an arc shape, there is also an advantage in that the air volume performance is improved by reducing a loss of flow rate.

Further, since the lower end of the diffuser is formed in an arc shape and grooves are formed at the diffuser, there is also an advantage in that it is possible to stably form ascending airflow.

Fifth, since only the lower end structure of the diffuser is changed, there is also an advantage in that it is possible to minimize structure deformation.

The effects of the present disclosure are not limited to those described above and other effects not stated herein may be made apparent to those skilled in the art from claims.

The advantages and features of the present disclosure, and methods of achieving them will be clear by referring to the exemplary embodiments that will be describe hereafter in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the exemplary embodiments described hereafter and may be implemented in various ways, and the exemplary embodiments are provided to complete the description of the present disclosure and let those skilled in the art completely know the scope of the present disclosure and the present disclosure is defined by claims. Like reference numerals indicate like components throughout the specification.

Hereinafter, the present disclosure will be described with reference to the drawings illustrating blowers according to embodiments of the present disclosure.

The entire structure of a blower <NUM> is described first with reference to <FIG> shows the entire external shape of the blower <NUM>.

The blower <NUM> may be referred to as another name such as an air conditioner, an air clean fan, air purifier, etc. in that the blower <NUM> suctions air and circulates the suctioned air.

The blower <NUM> according to an embodiment of the present disclosure may include a suction module <NUM> that suctions air and a blowing module <NUM> that discharges suctioned air.

The blower <NUM> may have a column shape of which the diameter decreases upward and the entire shape of the blower <NUM> may be a conical shape or a truncated cone shape. When the cross-section narrows upward, there is an advantage in that the center of gravity lowers and a danger of a fall due to external shock is decreased. However, a shape of which the cross-section does not narrow upward unlike the present embodiment is possible.

The suction module <NUM> may be formed such that the diameter gradually decreases upward and the blowing module <NUM> may also be formed such that the diameter gradually decreases upward.

The suction module <NUM> may include a base <NUM>, a lower case <NUM> disposed on the base <NUM>, and a filter <NUM> disposed in the lower case <NUM>.

The base <NUM> may be seated on the ground and can support load of the blower <NUM>. The lower case <NUM> and the filter <NUM> may be seated on the base <NUM>.

The lower case <NUM> may have a cylindrical external shape and may form a space in which the filter <NUM> is disposed therein A suction hole <NUM> that open to the inside of the lower case <NUM> may be formed at the lower case <NUM>. A plurality of suction holes <NUM> may be formed along the edge of the lower case <NUM>.

The filter <NUM> may have a cylindrical external shape and can filter out foreign substance contained in the air suctioned through the suction hole <NUM>.

The blowing module <NUM> may be separated and disposed into two column shapes extending up and down. The blower module <NUM> may include a first tower <NUM> and a second tower <NUM> that are disposed to be spaced apart from each other. The blowing module <NUM> may include a tower base <NUM> connecting the first tower <NUM> and the second tower <NUM> with the suction module <NUM>. The tower base <NUM> may be disposed on the suction module <NUM> and may be disposed under the first tower <NUM> and the second tower <NUM>.

The tower base <NUM> may have a cylindrical external shape and may form a continuous outer circumferential surface with the suction module <NUM> by being disposed on the suction module <NUM>.

The upper surface of the tower base <NUM> may be formed to be concave downward and may form a tower base upper surface <NUM> extending forward and rearward. The first tower <NUM> may extend upward from a side 211a of the tower base upper surface <NUM> and the second tower <NUM> may extend upward from another side 211b of the tower base upper surface <NUM>.

The tower base <NUM> may distribute filtered air supplied from the inside of the suction module <NUM> and may provide the distributed air to the first tower <NUM> and the second tower <NUM>.

The tower base <NUM>, the first tower <NUM>, and the second tower <NUM> each may be manufactured as a separate part and may be manufactured in an integrated type. The tower base <NUM> and the first tower <NUM> may form a continuous external circumferential surface of the blower <NUM>, and the tower base <NUM> and the second tower <NUM> may form the continuous external circumferential surface of the blower <NUM>.

Unlike the present disclosure, the first tower <NUM> and the second tower <NUM> may be assembly directly to the suction module <NUM> without the tower base <NUM> and may be integrally manufactured with the suction module <NUM>.

The first tower <NUM> and the second tower <NUM> may be disposed to be spaced apart from each other and a blowing space S may be formed between the first tower <NUM> and the second tower <NUM>.

The blowing space S may be understood as a space being open on the front, the rear, and the top between the first tower <NUM> and the second tower <NUM>.

The external shape of the blowing module <NUM> composed of the first tower <NUM>, the second tower <NUM>, and the blowing space S may be a truncated cone shape.

Discharge holes <NUM> and <NUM> formed at the first tower <NUM> and the second tower <NUM>, respectively, may discharge air toward the blowing space S. When the discharge holes <NUM> and <NUM> need to be discriminated, the discharge hole formed at the first tower <NUM> is referred to as a first discharge hole <NUM> and the discharge hole formed at the second tower <NUM> is referred to as a second discharge hole <NUM>.

The first tower <NUM> and the second tower <NUM> may be symmetrically discharged with the blowing space S therebetween. Since the first tower <NUM> and the second tower <NUM> are symmetrically discharged, flow is uniformly distributed in the blowing space S, so it is more advantageous in control of horizontal airflow and ascending airflow.

The first tower <NUM> may include a first tower case <NUM> forming the external shape of the first tower <NUM> and the second tower <NUM> may include a second tower case <NUM> forming the external shape of the second tower <NUM>. The first tower case <NUM> and the second tower case <NUM> may be referred to as upper cases that are disposed on the lower case <NUM> and have the discharge holes <NUM> and <NUM> discharging air, respectively.

The first discharge hole <NUM> may be formed at the first tower <NUM> to extend in the up-down direction and the second discharge hole <NUM> may be formed at the second tower <NUM> to extend up and down.

The flow direction of air discharged from the first tower <NUM> and the second tower <NUM> may be formed in the front-rear direction.

The width of the blowing space S that is the gap between the first tower <NUM> and the second tower <NUM> may be formed to be the same in the up-down direction. However, the upper end width of the blowing space S may be formed to be narrower or wider than the lower end width.

By uniformly forming the width of the blowing space S in the up-down direction, it is possible to uniformly distribute the air, which flows to the front of the blowing space S, in the up-down direction.

When the width of the upper side and the width of the lower side are different, the flow speed at the wide side may be low and a different of a speed may be generated in the up-down direction. When a flow different of air is generated in the up-down direction, the supply amount of clean air may be changed in accordance with the position in the up-down direction.

Air discharged from each of the first discharge hole <NUM> and the second discharge hole <NUM> may join in the blowing space S and then may be supplied to a user.

Air discharged from the first discharge hole <NUM> and air discharged from the second discharge hole <NUM> may join in the blowing space S and then supplied to a user without separately flowing to the user.

The blowing space S may be used as a space in which discharged air is joined and mixed. Indirect airflow is generated in the air around the blower <NUM> by the discharged air that is discharged to the blowing space S, so the air around the blower <NUM> may flow toward the blowing space S.

As the discharged air of the first discharge hole <NUM> and the discharged air of the second discharge hole <NUM> join in the blowing space S, straightness of discharged air can be improved. As the discharged air of the first discharge hole <NUM> and the discharged air of the second discharge hole <NUM> join in the blowing space S, the air around the first tower <NUM> and the second tower <NUM> may also be induced to flow forward long the outer circumferential surface of the blowing module <NUM> by the indirect airflow.

The first tower case <NUM> may include: a first tower upper end 221a forming the upper surface of the first tower <NUM>; a first tower front end 221b forming the front surface of the first tower <NUM>; a first tower rear end 221c forming the rear surface of the first tower <NUM>; a first outer wall 221d forming the outer circumferential surface of the first tower <NUM>, and a first inner wall 221e forming the inner surface of the first tower <NUM>.

The second tower case <NUM> may include: a second tower upper end 231a forming the upper surface of the second tower <NUM>; a second tower front end 231b forming the front surface of the second tower <NUM>; a second tower rear end 231c forming the rear surface of the second tower <NUM>; a second outer wall 231d forming the outer circumferential surface of the second tower <NUM>, and a second inner wall 231e forming the inner surface of the second tower <NUM>.

The first outer wall 221d and the second outer wall 231d are formed to be convex outward in the radial direction, so they may form the outer circumferential surfaces of the first discharge hole <NUM> and the second discharge hole <NUM>, respectively.

The first inner wall 221e and the second inner wall 231e are formed to be convex inward in the radial direction, so they may form the inner circumferential surfaces of the first discharge hole <NUM> and the second discharge hole <NUM>, respectively.

The first discharge hole <NUM> may be formed in the first inner wall 221e to extend in the up-down direction and may be formed to be open inward in the radial direction. The second discharge hole <NUM> may be formed in the second inner wall 231e to extend in the up-down direction and may be formed to be open inward in the radial direction.

The first discharge hole <NUM> may be formed at a position closer to the first tower rear end 221c of the first tower front end 221b. The second discharge hole <NUM> may be formed at a position closer to the second tower rear end 231c of the second tower front end 231b.

A first board slot <NUM> that a first airflow shifter <NUM> that will be described below passes through may be formed in the first inner wall 221e to extend in the up-down direction. A second board slot <NUM> that a second airflow shifter <NUM> that will be described below passes through may be formed in the second inner wall 231e to extend in the up-down direction. The first board slot <NUM> and the second board slot <NUM> may be formed to be open inward in the radial direction.

The first board slot <NUM> may be formed at a position closer to the first tower front end 221b of the first tower rear end 221c. The second board slot <NUM> may be formed at a position closer to the second tower front end 231b of the second tower rear end 231c. The first board slot <NUM> and the second board slot <NUM> may be formed to face each other.

Hereafter, the internal structure of the blower <NUM> is described with reference to <FIG> and <FIG>. <FIG> is a cross-sectional projection view cutting the blower <NUM> along line P-P' shown in <FIG> and <FIG> is a cross-sectional projection view cutting the blower <NUM> along line Q-Q' shown in <FIG>.

Referring to <FIG>, a driving module <NUM> that rotates the blower <NUM> in the circumferential direction may be disposed on the base <NUM>. A driving space <NUM> in which the driving module <NUM> is disposed may be formed on the base <NUM>.

The filter <NUM> may be disposed on the driving space <NUM>. The external shape of the filter <NUM> may be a cylindrical shape and a cylindrical filter hole <NUM> may be formed in the filter <NUM>.

Air suctioned inside through the suction hole <NUM> may flow to the filter hole <NUM> through the filter <NUM>.

A suction grill <NUM> that air, which passes through the filter <NUM> and flows upward, passes through may be disposed on the filter <NUM>. The suction grill <NUM> may be disposed between a fan assembly <NUM> that will be described below and the filter <NUM>. The suction grill <NUM> may prevent a user's hand from being put into the fan assembly <NUM> when the lower case <NUM> is removed and the filter <NUM> is separated from the blower <NUM>.

The fan assembly <NUM> may be disposed on the filter <NUM> and may generate a suction force for air outside the blower <NUM>.

By driving of the fan assembly <NUM>, the air outside the blower <NUM> may sequentially pass through the suction hole <NUM> and the filter hole <NUM> and flow to the first tower <NUM> and the second tower <NUM>.

A pressurizing space <NUM> in which the fan assembly <NUM> is disposed may be formed between the filter <NUM> and the blowing module <NUM>.

A first distribution space <NUM> in which air passing through the pressurizing space <NUM> flows upward may be formed in the first tower <NUM>, and a second distribution space <NUM> in which air passing through the pressurizing space <NUM> flows upward may be formed in the second tower <NUM>. The tower base <NUM> may distribute air passing through the pressurizing space <NUM> to a first distribution space <NUM> and a second distribution space <NUM>. The tower base <NUM> may be a channel connecting the first and second towers <NUM> and <NUM> and the fan assembly <NUM>.

The first distribution space <NUM> may be formed between the first outer wall 221d and the first inner wall 221e. The second distribution space <NUM> may be formed between the second outer wall 231d and the second inner wall 231e.

The first tower <NUM> may include a first flow guide <NUM> that guides a flow direction of air in the first distribution space <NUM>. A plurality of first flow guides <NUM> may be disposed to be spaced part from each other up and down.

The first flow guide <NUM> may be formed to protrude toward the first tower front end 221b from the first tower rear end 221c. The first flow guide <NUM> may be spaced apart from the first tower front end 221b in the front-read direction. The first flow guide <NUM> may extend to be inclined downward toward the front. A first guide front end 224a forming the front surface of the first flow guide <NUM> may be positioned lower than a first guide rear end 224b forming the rear surface of the first flow guide <NUM>. The downwardly inclined angles of first flow guides disposed at the upper portion of a plurality of first flow guides <NUM> may be smaller.

The second tower <NUM> may include a second flow guide <NUM> that guides a flow direction of air in the second distribution space <NUM>. A plurality of second flow guides <NUM> may be disposed to be spaced part from each other up and down.

The second flow guide <NUM> may be formed to protrude toward the second tower front end 231b from the second tower rear end 231c. The second flow guide <NUM> may be spaced apart from the second tower front end 231b in the front-read direction. The second flow guide <NUM> may extend to be inclined downward toward the front. A second guide front end 234a forming the front surface of the second flow guide <NUM> may be positioned lower than a second guide rear end 234b forming the rear surface of the second flow guide <NUM>. The downwardly inclined angles of second flow guides disposed at the upper portion of a plurality of second flow guides <NUM> may be smaller.

The first flow guide <NUM> may guide air discharged from the fan assembly <NUM> to flow toward the first discharge hole <NUM>. The second flow guide <NUM> may guide air discharged from the fan assembly <NUM> to flow toward the second discharge hole <NUM>.

Referring to <FIG>, the fan assembly <NUM> may include: a fan motor <NUM> that generates power; a motor housing <NUM> in which the fan motor <NUM> is accommodated; a fan <NUM> that is rotated by receiving power from the fan motor <NUM>; and a diffuser <NUM> that guides the flow direction of air pressurized by the fan <NUM>.

The fan motor <NUM> may be disposed on the fan <NUM> and may be connected with the fan <NUM> through a motor shaft <NUM> extending downward from the fan motor <NUM>.

The motor housing <NUM> may include a first motor housing <NUM> covering the upper portion of the fan motor <NUM> and a second motor housing <NUM> covering the lower portion of the fan motor <NUM>.

The first discharge hole <NUM> may extend upward from a side 211a of the tower base upper surface <NUM>. A first discharge hole lower end 222d may be formed at the side 211a of the tower base upper surface <NUM>.

The first discharge hole <NUM> may be formed to be spaced under the first tower upper end 221a. A first discharge hole upper end 222c may be formed to be spaced under the first tower upper end 221a.

The first discharge hole <NUM> may extend to be inclined in the up-down direction. The first discharge hole <NUM> may extend to be inclined forward toward the upper portion. The first discharge hole <NUM> may extend to be inclined rearward with respect to an up-down axis Z extending in the up-down direction.

The first discharge hole front end 222a and the first discharge hole rear end 222b may extend to be inclined in the up-down direction and may extend in parallel with each other. The first discharge hole front end 222a and the first discharge hole rear end 222b may extend to be inclined rearward with respect to the up-down axis Z extending in the up-down direction.

The first tower <NUM> may include a first discharge guide <NUM> that guides air in the first distribution space <NUM> to the first discharge hole <NUM>.

The first tower <NUM> may be symmetric to the second tower <NUM> with the blowing space S therebetween and may have the same shape and structure as the second tower <NUM>. The above description of the first tower <NUM> may be applied to the second tower <NUM> in the same way.

Hereafter, an air discharge structure of the blower <NUM> for inducing Coanda effect is described with reference to <FIG> and <FIG>. <FIG> is a projection view showing the blower <NUM> in the right downward direction from above and <FIG> is a projection view showing the blower <NUM> cut along line R-R' shown in <FIG> in the upward direction.

Referring to <FIG>, gaps D0, D1, and D2 between the first inner wall 221e and the second rear wall 231e may become smaller as they are close to the center of the blowing space S.

The first inner wall 221e and the second inner wall 231e may be formed to be convex inward in the radial direction, and the shortest distance D0 may be formed between the apexes of the first inner wall 221e and the second inner wall 231e. The shortest distance D0 may be formed at the center of the blowing space S.

The first discharge hole <NUM> may be formed behind the position where the shortest distance D0 is formed. The second discharge hole <NUM> may be formed behind the position where the shortest distance D0 is formed.

The first tower front end 221b and the second tower front end 231b may be spaced apart from each other by a first gap D1. The first tower rear end 221c and the second tower rear end 231c may be spaced apart from each other by a second gap D2.

The first gap D1 and the second gap D2 may be the same. The first gap D1 may be larger than the shortest distance D0 and the second gap D2 may be larger than the shortest distance D0.

The gap between the first inner wall 221e and the second inner wall 231e may decrease from the rear ends 221c and 231c to the position where the shortest distance D0 is formed and may increase from the position where the shortest distance D0 is formed to the front ends 221b and 231b.

The first tower front end 221b and the second tower front end 231b may be formed to be inclined with respect to a front-rear axis X.

Tangent lines extending from the first tower front end 221b and the second tower front end 231b each may have a predetermined inclination angle A with respect to the front-rear axis X.

A portion of the air discharged forward through the blowing space S may flow with the inclination angle A with respect to the front-rear axis X.

By the structure described above, a diffusion angle of air discharged forward through the blowing space S may increase.

The first airflow shifter <NUM> that will be described below may be inserted in the first board slit <NUM> when air is discharged forward from the blowing space S.

The second airflow shifter <NUM> that will be described below may be inserted in the second board slit <NUM> when air is discharged forward from the blowing space S.

Referring to <FIG>, the flow direction of the air discharged toward the blowing space S may be guided by the first discharge guide <NUM> and the second discharge guide <NUM>.

The first discharge guide <NUM> may include a first inner guide 225a connected with the first inner wall 221e and a first outer guide 225b connected with the first outer wall 221d.

The first inner guide 225a may be manufactured integrally with the first inner wall 221e, but may be manufactured as a separate part.

The first outer guide 225b may be manufactured integrally with the first outer wall 221d, but may be manufactured as a separate part.

The first inner guide 225a may be formed to protrude toward the first distribution space <NUM> from the first inner wall 221e.

The first outer guide 225b may be formed to protrude toward the first distribution space <NUM> from the first outer wall 221d. The first outer guide 225b may be formed to be spaced outside the first inner guide 225a, and may form the first discharge hole <NUM> between the first outer guide 225b and the first inner guide 225a.

The radius of curvature of the first inner guide 225a may be formed to be smaller than the radius of curvature of the first outer guide 225b.

Air of the first distribution space <NUM> may flow between the first inner guide 225a and the first outer guide 225b and flow to the blowing space S through the first discharge hole <NUM>.

The second discharge guide <NUM> may include a second inner guide 235a connected with the second inner wall 231e and a second outer guide 235b connected with the second outer wall 231d.

The second inner guide 235a may be manufactured integrally with the second inner wall 231e, but may be manufactured as a separate part.

The second outer guide 235b may be manufactured integrally with the second outer wall 231d, but may be manufactured as a separate part.

The second inner guide 235a may be formed to protrude toward the second distribution space <NUM> from the second inner wall 231e.

The second outer guide 235b may be formed to protrude toward the second distribution space <NUM> from the second outer wall 231d. The second outer guide 235b may be formed to be spaced outside the second inner guide 235a, and may form the second discharge hole <NUM> between the second outer guide 235b and the second inner guide 235a.

The radius of curvature of the second inner guide 235a may be formed to be smaller than the radius of curvature of the second outer guide 235b.

Air of the second distribution space <NUM> may flow between the second inner guide 235a and the second outer guide 235b and flow to the blowing space S through the second discharge hole <NUM>.

Widths w1, w2, and w3 of the first discharge hole <NUM> may be formed to gradually decrease toward the outlet from the inlet of the first discharge guide <NUM> and then increase.

The size of the inlet width w1 of the first discharge guide <NUM> may be larger than the outlet width w3 of the first discharge guide <NUM>.

The inlet width w1 may be defined as the gap between an outer end of the first inner guide 225a and an outer end of the first outer guide 225b. The outlet width w3 may be defined as the gap between the first discharge hole front end 222a that is an inner end of the first inner guide 225a and the first discharge hole rear end 222b that is an inner end of the first outer guide 225b.

The sizes of the inlet width w1 and the outlet width w3 may be larger than the size of a shortest width w2 of the first discharge hole <NUM>.

The shortest width w2 may be defined as the shortest distance between the first discharge hole rear end 222b and the first inner guide 225a.

The widths of the first discharge hole <NUM> may gradually decrease from the inlet of the first discharge guide <NUM> to the position where the shortest width w2 is formed and may gradually increase from the position where the shortest width w2 is formed to the outlet of the first discharge guide <NUM>.

The second discharge guide <NUM>, similar to the first discharge guide <NUM>, may also have a second discharge hole front end 232a and a second discharge hole rear end 232b and may have distribution of width the same as the first discharge guide <NUM>.

Hereafter, an air direction change by an airflow shifter <NUM> is described with reference to <FIG> and <FIG>. <FIG> is a view showing the case in which the airflow shifter <NUM> protrudes to the blowing space S and the blower <NUM> forms ascending airflow and <FIG> is a view showing the operation principle of the airflow shifter <NUM>.

Referring to <FIG>, the airflow shifter <NUM> may protrude toward the blowing space S and may change the flow of air, which is discharged forward through the blowing space S, into ascending air.

The airflow shifter <NUM> may include a first airflow shifter <NUM> disposed in the first tower case <NUM> and a second airflow shifter <NUM> disposed in the second tower case <NUM>.

The first airflow shifter <NUM> and the second airflow shifter <NUM> may block the front of the blowing space S by protruding from the blowing space S from the first tower <NUM> and the second tower <NUM>, respectively.

When the first airflow shifter <NUM> and the second airflow shifter <NUM> protrude and block the front of the blowing space S, air discharged through the first discharge hole <NUM> and the second discharge hole <NUM> is blocked by the airflow shifter <NUM>, so the air may flow upward Z.

When the first discharge hole <NUM> and the second discharge hole <NUM> are inserted into the first tower <NUM> and the second tower <NUM>, respectively, and open the front of the blowing space S, air discharged through the first discharge hole <NUM> and the second discharge hole <NUM> may flow forward X through the blowing space S.

Referring to <FIG>, the airflow shifters <NUM> and <NUM> may include: a board <NUM> protruding toward the blowing space; a motor <NUM> providing a driving force to the board <NUM>; a board guide <NUM> guiding a movement direction of the board <NUM>; and a cover <NUM> supporting the motor <NUM> and the board guide <NUM>.

The first airflow shifter <NUM> is exemplified in the following description, but the following description of the first airflow shifter <NUM> may also be applied to the second airflow shifter <NUM> in the same way.

The board <NUM>, as shown in <FIG> and <FIG>, may be inserted in the first board slit <NUM>. The board <NUM> may protrude to the blowing space S through the first board slit <NUM> when the motor <NUM> is driven. The board <NUM> may have an arch shape of which the shape of a transverse cross-section is an arc shape. The board <NUM> may move in the circumferential direction and protrude to the blowing space S when the motor <NUM> is driven.

The motor <NUM> may be connected with a pinion gear 322a and may rotate the pinion gear 322a. The motor <NUM> may rotate the pinion gear 322a clockwise and counterclockwise.

The board guide <NUM> may have a plate shape extending up and down. The board guide <NUM> may include a guide slit 323a extending to be inclined up and down and a rack 323b formed to protrude toward the pinion gear 322a.

The rack 323b may be engaged with the pinion gear 322a. When the motor <NUM> is driven and the pinion gear 322a is rotated, the rack 323b engaged with the pinion gear 322a may be moved up and down.

A guide protrusion 321a formed at the board <NUM> to protrude toward the board guide <NUM> may be inserted in the guide slit 323a.

When the board guide <NUM> is moved up and down in accordance with up/down movement of the rack 323b, the guide protrusion 321a may be moved by force from the guide slit 323a. As the board guide <NUM> is moved up and down, the guide protrusion 321a may be diagonally moved in the guide slit 323a.

When the rack 323b is moved up, the guide protrusion 321a may be moved along the guide slit 323a and may be positioned at the lowermost end of the guide slit 323a. When the guide protrusion 321a is positioned at the lowermost end of the guide slit 323a, the board <NUM>, as shown in <FIG> and <FIG>, may be completely hidden in the first tower <NUM>. When the rack 323b is moved up, the guide slit 323a is also moved up, so the guide protrusion 321a may be moved in the circumferential direction o the same horizontal surface along the guide slit 323a.

When the rack 323b is moved down, the guide protrusion 321a may be moved along the guide slit 323a and may be positioned at the uppermost end of the guide slit 323a. When the guide protrusion 321a is positioned at the uppermost end of the guide slit 323a, the board <NUM>, as shown in <FIG>, may protrude toward the blowing space S from the first tower <NUM>. When the rack 323b is moved down, the guide slit 323a is also moved down, so the guide protrusion 321a may be moved in the circumferential direction o the same horizontal surface along the guide slit 323a.

The cover <NUM> may include: a first cover 324a disposed outside the board guide <NUM>; a second cover 324b disposed inside the board guide <NUM> and being in close contact with the first inner surface 221e; a motor support plate 324c extending upward from the first cover 324a and connected with the motor <NUM>; and a stopper 324b restricting up/down movement of the board guide <NUM>.

The first cover 324a may cover the outer side of the board guide <NUM> and the second cover 324b may cover the inner side of the board guide <NUM>. The first cover 324a may separate the space in which the board guide <NUM> is disposed from the first distribution space <NUM>. The second cover 324b may prevent the board guide <NUM> from coming in contact with the first inner wall 221e.

The motor support plate 324c may extend upward from the first cover 324a and support load of the motor <NUM>.

The stopper 324d may be formed to protrude toward the board guide <NUM> from the first cover 324a. A locking protrusion (not shown) that is locked to the stopper 324d in accordance with up/down movement may be formed on one surface of the board guide <NUM>. When the board guide <NUM> is moved up and down, the locking protrusion (not shown) is locked to the stopper 324d, so the up/down movement of the board guide <NUM> may be restricted.

Hereafter, the fan <NUM> according to an embodiment of the present disclosure is described with reference to <FIG> and <FIG>. <FIG> is a perspective view of the fan <NUM> according to an embodiment of the present disclosure and <FIG> is a view showing the fan <NUM> according to an embodiment of the present disclosure upward from under.

A mixed-flow fan may be used as the fan <NUM>. However, the kind of the fan <NUM> is not limited to a mixed-flow fan and other kinds of fans may be used.

The fan <NUM> may include a hub <NUM> coupled to the fan <NUM>, a shroud <NUM> disposed to be spaced under the hub <NUM>, and a plurality of blades <NUM> connecting the shroud <NUM> and the hub <NUM>.

A motor shaft <NUM> of the fan motor <NUM> is coupled to the center of the hub <NUM>, and when the fan motor <NUM> is operated, the hub <NUM> may be rotated with the motor shaft <NUM>.

When the fan <NUM> is rotated, air may flow toward the hub <NUM> from the shroud <NUM> of the fan <NUM>.

The hub <NUM> may be formed in a bowl shape that is concave downward and the fan motor <NUM> may be disposed on the hub <NUM>.

The hub <NUM> may include a first hub surface <NUM> disposed on the shroud <NUM> to face the shroud <NUM>.

The first hub surface <NUM> may be a conical shape protruding downward, may have a transverse cross-section of which the shape is a circular shape, and may be a shape in which the diameter of a cross-section increases toward the upper end.

The shroud <NUM> may be disposed to be space under the hub <NUM> and may be disposed to surround the hub <NUM>.

At least a portion of the hub <NUM> may be inserted in the center portion of the shroud <NUM>. The diameter of the hub <NUM> may be smaller than the diameter of the shroud <NUM>.

The shroud <NUM> may include a rim portion <NUM> extending in the circumferential direction and a supporting portion <NUM> extending to be inclined upward from the rim portion <NUM>. The rim portion <NUM> and the supporting portion <NUM> may be integrally manufactured through injection molding.

The rim portion <NUM> may be formed in an annular shape. Air may be suctioned into the rim portion <NUM>.

The rim portion <NUM> may be formed such that the up-down height is longer than the thickness. The rim portion <NUM> may vertically extend up and down.

The extension length of the rim portion <NUM> in the up-down direction and the upward inclined extension length of the supporting portion <NUM> may have a ratio of <NUM>:<NUM>.

The blades <NUM> may connect the hub <NUM> and the shroud <NUM> that are disposed to be spaced apart from each other. The upper ends of the blades <NUM> may be coupled to the hub <NUM> and the lower ends may be coupled to the shroud <NUM>.

The blade <NUM> may include: a positive pressure surface <NUM> disposed toward the hub <NUM>; a negative pressure surface <NUM> disposed toward the shroud <NUM>; a root portion <NUM> connected with the hub <NUM>; a tip portion <NUM> connected with the shroud <NUM>; a leading edge <NUM> connecting one end of the root portion <NUM> and one end of the tip portion <NUM>; and a trailing edge <NUM> connecting another end of the root portion <NUM> and another end of the tip portion <NUM>.

The root portion <NUM> and the tip portion <NUM> may be formed an airfoils.

The leading edge <NUM> may be a front end that first comes in contact with air when the hub <NUM> is rotated, and the trailing edge <NUM> may be a rear end that latest comes in contact with air when the hub <NUM> is rotated.

The leading edge <NUM> may be disposed toward the rotation center of the fan <NUM> and the trailing edge <NUM> may be disposed toward the outside in the radial direction of the fan <NUM>.

The root portion <NUM> may be in contact with the first hub surface <NUM> of the hub <NUM> in an inclined type.

The top portion <NUM> may be in contact with the supporting portion <NUM> of the shroud <NUM> in an inclined type.

The inclined extension length of the first hub surface <NUM> may be smaller than the length of the root portion <NUM>. The root portion <NUM> may be connected to be inclined with respect to the first hub surface <NUM>.

The inclined extension length of the supporting portion <NUM> may be smaller than the length of the tip portion <NUM>. The tip portion <NUM> may be connected to be inclined with respect to the supporting portion <NUM>.

A plurality of blades <NUM> may be disposed to be spaced in the circumferential direction. The leading edge <NUM> of each of the plurality of blades <NUM> may be disposed to at least partially face the trailing edge <NUM> of adjacent blades <NUM>. Accordingly, when the fan <NUM> is seen from under, as in <FIG>, the leading edge <NUM> of any one blade <NUM> may be seen like overlapping the trailing edge <NUM> of an adjacent blade <NUM>.

Hereafter, the position relationship of the hub <NUM> and the shroud <NUM> is described with reference to <FIG> and <FIG>. <FIG> is a cross-sectional projection view cutting the fan <NUM> in the longitudinal direction and <FIG> is a view enlarging the region M shown in <FIG>.

The hub <NUM> may include a second hub surface <NUM> disposed toward the fan motor <NUM> and a shaft coupling portion <NUM> to which the motor <NUM> is coupled.

The first hub surface <NUM> may be disposed toward the lower side and the second hub surface <NUM> may be disposed toward the upper side. The fan motor <NUM> may be inserted in the second hub surface <NUM> and connected with the hub <NUM>.

The motor shaft <NUM> of the fan motor <NUM> may be coupled to the shaft coupling portion <NUM>. The shaft coupling portion <NUM> may be disposed to pass through the hub <NUM> in the up-down direction. The rotation center of the fan <NUM> may be formed inside the shaft coupling portion <NUM>. The shaft coupling portion <NUM> may be formed integrally with the first hub surface <NUM> and the second hub surface <NUM>.

The shaft coupling portion <NUM> may be formed to protrude downward from the first hub surface <NUM> and may be formed to protrude upward from the second hub surface <NUM>.

The shaft coupling portion <NUM> may form a hub lower end 510a by protruding downward. The shaft coupling portion <NUM> may form a hub protrusion end 510c by protruding upward. The shaft coupling portion <NUM> may form a hub middle portion by being connected with the first hub surface <NUM>.

The first hub surface <NUM> and the second hub surface <NUM> may extend to be inclined outward in the radial direction and may form a hub upper end 510b.

The hub <NUM> may extend in a straight line shape to be inclined outward in the radial direction. The inclined extension direction of the hub <NUM> is defined as L1 and the inclined angle of the hub <NUM> is defined as a hub inclination angle θ1. The diameter of the hub <NUM> may increase toward the outside in the radial direction, and the internal space of the hub <NUM> may expand upward. The hub inclination angle θ1 may be formed in the range of <NUM> degrees to <NUM> degrees.

The rim portion <NUM> may extend in the up-down direction and may form a fan suction hole <NUM> therein. The rim portion <NUM> may include a rim portion lower end 520a constituting the lower portion of the fan suction hole <NUM> and a rim portion upper end 520d connected with the supporting portion <NUM>.

The supporting portion <NUM> may extend to be inclined outward in the radial direction from the rim portion upper end 520c and may form a shroud edge 520b at the outermost side in the radial direction. The rim portion upper end 520c may be the boundary of the rim portion <NUM> and the supporting portion <NUM>.

The shroud <NUM> may include a first shroud surface 522a disposed toward the lower side and a second shroud surface 522b disposed toward the upper side. The first shroud surface 522a may be formed to face the suction grill <NUM> and the second shroud surface 522b may be formed to face the first hub surface <NUM>. The rim portion <NUM> may protrude downward from the first shroud surface 522a. The blades <NUM> may be coupled to the second shroud surface 522b.

The hub upper end 510b may be disposed inside further than the rim portion <NUM> in the radial direction. It is possible to sufficiently secure the length of the blades <NUM> and increase an air volume by sufficiently spacing the hub upper end 510b and the shroud edge 520b.

At least a portion of the diffuser <NUM> that will be described below may be disposed between the hub upper end 510b and the shroud edge 520b. The height at which at least a portion of the diffuser <NUM> is disposed may be formed between the hub upper end 510b and the shroud edge 520b.

The shroud <NUM> may extend in a straight line shape to be inclined outward in the radial direction. The inclined extension direction of the shroud <NUM> is defined as L2 and the inclined angle of the shroud <NUM> is defined as a shroud inclination angle θ2. The diameter of the shroud <NUM> may increase toward the outside in the radial direction, and the internal space of the shroud <NUM> may expand upward. The shroud inclination angle θ2 may be formed in the range of <NUM> degrees to <NUM> degrees.

The hub inclination angle θ1 and the shroud inclination angle θ2 may be formed to be different, and a flow passage through which air flowing inside through the fan suction hole <NUM> may be formed between the hub <NUM> and the shroud <NUM>. The contained angle between the hub <NUM> and the shroud <NUM> is defined as an expansion angle θ3. A flow passage having the size of the expansion angle θ3 may be formed between the hub <NUM> and the shroud <NUM>.

The hub inclination angle θ1 may be formed to be larger than the shroud inclination angle θ2. Since the hub inclination angle θ1 is formed to be larger than the shroud inclination angle θ2, it is possible to increase the size of the expansion angle θ3 and it is possible to reduce friction resistance acting in the air passing through the fan suction hole <NUM>.

The hub <NUM> may have an outer surface <NUM> extending to be inclined at a first angle θ8 with respect to the motor shaft <NUM>. The outer surface <NUM> may be the first hub surface <NUM>.

The shroud <NUM> may extend to be inclined at a second angle θ9 that is larger than the first angle θ8 with respect to the motor shaft <NUM>.

The inner surface of the supporting portion <NUM> of the shroud <NUM> may face the outer surface <NUM> of the hub <NUM> with the blades <NUM> therebetween.

The motor shaft <NUM> may rotate the hub <NUM> and the blades <NUM> by being inserted in the shaft coupling portion <NUM> and may form a rotation axis MX of the fan <NUM>.

The hub upper end 510b may form a hub area HA by being spaced apart from the rotation axis MX by a predetermined angle. The shroud edge 520b may form a shroud area SA by being spaced apart from the rotation axis MX by a predetermined angle.

The size of the shroud area SA may be larger than the size of the hub area HA.

The hub <NUM> may extend to be inclined at the first angle θ8 with respect to a first axis MX1 that is parallel with the rotation axis MX and passes through the shaft coupling portion <NUM>.

The shroud <NUM> may extend to be inclined at the second angle θ9 with respect to a second axis MX2 that is parallel with the rotation axis MX and passes through the rim portion <NUM>.

The size of the first angle θ8 may be smaller than the second angle θ9.

The sum of the hub inclination angle θ1 and the first angle θ8 may be <NUM> degrees, and the sum of the shroud angle θ2 and the second angle θ9 may be <NUM> degrees.

The height of the rim portion upper end 520c is defined as H1, the height of the hub lower end 510a is defined as H2, the height of the shroud edge 520b is defined as H3, the height of the hub middle portion 510d is defined as H4, and the height of the hub protrusion end 510c is defined as H5.

The fan <NUM> may be formed in a shape satisfying the relationship of H5>H4>H3>H2>H1. In detail, the hub lower end 510a may be formed higher than the rim portion upper end 520c, the shroud edge 520b may be formed higher than the hub lower end 510a, the hub middle portion 510d may be formed higher than the shroud edge 520b, and the hub protrusion end 510c may be formed higher than the hub middle portion 510d.

The height H3 of the shroud edge 520b may be formed between the height H2 of the hub lower end 510a and the height H5 of the hub protrusion end 510c. The height H3 of the shroud edge 520b may be formed between the height H2 of the hub lower end 510a and the height H4 of the hub middle portion 510d.

The first hub surface <NUM> may include a first guide surface 511a connected with the shaft coupling portion <NUM> and a second guide surface 511b extending to be inclined upward from the first guide surface 511a. The first guide surface 511a may horizontally extend from the shaft coupling portion <NUM> and the second guide surface 511b may extend upward from the outer end of the first guide surface 511a.

Due to the structure described above, air flowing inside through the fan suction hole <NUM> and reaching the first guide surface 511a may flow upward along the second guide surface 511b without going out to the upper side of the shroud edge 520b. Air flowing inside through the fan suction hole <NUM> may be guided to flow in the range of the expansion angle θ3 without going to the outside of the fan <NUM> through the shroud 520b, so a flow loss can be reduced.

Hereafter, an operation effect on air volume and noise according to the shroud inclination angle θ2 is described with reference to <FIG> and <FIG>. <FIG> shows an air volume according to the shroud inclination angle θ2 in a graph and <FIG> shows noise according to the shroud inclination angle θ2 in a graph.

Table <NUM> shows experiment results of the number of revolutions, noise, and sharpness of the fan <NUM> when an air volume is 10CMM. Referring to <FIG>, it can be seen that as the RPM increases, the air volume increases when the shroud inclination angle θ2 is <NUM> degrees, <NUM> degrees, and <NUM> degrees.

Referring to <FIG>, it can be seen that as the air volume increases, the noise also increases when the shroud inclination angle θ2 is <NUM> degrees, <NUM> degrees, and <NUM> degrees. However, it can be seen that as the shroud inclination angle θ2 decreases, noise is large, and as the shroud inclination angle θ2 increases, noise decreases.

The expansion angle θ3 may be set in the range of <NUM> degrees and <NUM> degrees in consideration of noise and an air volume, and preferably, the expansion angle θ3 may be <NUM> degrees.

Hereafter, the blades <NUM> according to an embodiment of the present disclosure is described with reference to <FIG> and <FIG>. <FIG> shows one blade <NUM> and <FIG> shows a plurality of airfoils <NUM>, <NUM>, <NUM>, and <NUM> constituting one blade <NUM>.

A great number of airfoils may be formed from the root portion <NUM> to the tip portion <NUM> of the blade <NUM>, and the blade <NUM> may be understood as a group of a plurality of airfoils. The airfoil may also be understood as a cross-sectional shape of the blade <NUM>. The root portion <NUM> and the tip portion <NUM> may be included in a plurality of airfoils.

In the plurality of airfoils, any one airfoil between the root portion <NUM> and the tip portion <NUM> may be defined as reference airfoils <NUM> and <NUM>.

The reference airfoils <NUM> and <NUM> may be defined as airfoils of which the distance from the root portion <NUM> and the tip portion <NUM> makes a constant reference ratio.

The distance from the reference airfoils <NUM> and <NUM> to the root portion <NUM> may be a first distance and the distance from the reference airfoils <NUM> and <NUM> to the tip portion <NUM> may be a second distance. The ratio of the first distance and the second distance may be <NUM>:<NUM>, and the reference airfoil <NUM> in this case may be defined as a first reference airfoil <NUM>. The ratio of the first distance and the second distance may be <NUM>;<NUM>, and the reference airfoil <NUM> in this case may be defined as a second reference airfoil <NUM>.

The leading edge <NUM> may be formed to be curved along the plurality of airfoils <NUM>, <NUM>, <NUM>, and <NUM>.

The root portion <NUM> may form a first intersection point 535a with the leading edge <NUM> and the tip portion <NUM> may form a second intersection point 536a with the leading edge <NUM>. The leading edge <NUM> may extend to be curved from the first intersection point 535a to the second intersection point 536a.

A virtual leading line L3 connecting the first intersection point 535a to the second intersection point 536a may be formed. The leading edge <NUM> may be formed to be spaced apart from the leading line L3.

The first reference airfoil <NUM> may form a third intersection point 537a with the leading edge <NUM> and the second reference airfoil <NUM> may form a fourth intersection point 538a with the leading edge <NUM>.

The third intersection point 537a may be understood as a point at which a first mean camber line CL1 of the first reference airfoil <NUM> crosses the leading edge <NUM>.

The fourth intersection point 538a may be understood as a point at which a second mean camber line CL2 of the second reference airfoil <NUM> crosses the leading edge <NUM>.

A third intersection point 537a and the fourth intersection point 538a may be formed to be spaced apart from the leading line L3.

The traces of the intersection points 535a, 536a, 537a, and 538a formed by rotation of the fan <NUM> may form a circle around the motor shaft <NUM>. The traces of the intersection points 535a, 536a, 537a, and 538a may be understood as constituting a portion of the trace of the leading edge <NUM>.

The third intersection point 537a may form a circular first trace C1 by rotation of the fan <NUM>. The fourth intersection point 538a may form a circular second trace C2 by rotation of the fan <NUM>.

The leading edge <NUM> of the blade <NUM> may be designed on the basis of inlet angles θ4 and θ5 of the reference airfoils <NUM> and <NUM>.

The first inlet angle θ4 of the first reference airfoil <NUM> may mean an angle made by an extension line of the first mean camber line CL1 and the first trace C1.

The tangential line of the first mean camber line CL1 at the third intersection point 537a is defined as a first tangential line T1 and the tangential line of the first trace C1 at the third intersection point 537a is defined as a first base line B1.

The first inlet angle θ4 of the first reference airfoil <NUM> may be understood as the angle between the first tangential line T1 and the first base line B1.

The second inlet angle θ4 of the second reference airfoil <NUM> may mean an angle made by an extension line of the second mean camber line CL2 and the second trace C2.

The tangential line of the second mean camber line CL2 at the fourth intersection point 538a is defined as a second tangential line T2 and the tangential line of the second trace C2 at the fourth intersection point 538a is defined as a second base line B2.

The second inlet angle θ5 of the second reference airfoil <NUM> may be understood as the angle between the second tangential line T2 and the second base line B2.

The blade <NUM> may be formed such that the inlet angle can be varied in a span direction. The inlet angle may be continuously varied in the span direction. The span direction may mean an extension direction of the leading edge <NUM> formed to be curved toward the second intersection point 538a from the first intersection point 537a.

The inlet angle of the blade <NUM> in the span direction may be changed to implement an appropriate airfoil at different positions of the leading edge <NUM> in accordance with the characteristics of flow at the positions. AS the inlet angle of the blade <NUM> in the span direction is changed, the shape of the leading edge <NUM> may be formed to be curved.

A virtual blade extending such that the leading edge has the same inlet angle in the span direction may be defined as a "first comparative blade". The inlet angle of the first comparative blade is the same in all airfoils.

The inlet angles θ4 and θ5 of the reference airfoils <NUM> and <NUM> of the blade <NUM> according to an embodiment of the present disclosure may be larger of the inlet angle of the first comparative blade.

A blade in which the leading edge straightly extends from the rood portion to the tip portion may be defined as a "second comparative blade". In the second comparative blade, the leading line L3 defined in the description of the present disclosure may coincide with the leading edge <NUM>.

The first comparative blade and the second comparative blade may have a comparative root portion and a comparative tip portion that are the same as the root portion <NUM> and the tip portion <NUM> of the present disclosure.

Comparing the inlet angles at the same position of the blade <NUM> of the present disclosure and the comparative blade, the inlet angle of the blade <NUM> of the present disclosure may be larger than the inlet angle of the comparative blade.

Table <NUM> is a table showing a noise resultant value according to the inlet angle of an airfoil. The inlet angle of an airfoil that is a comparison target mean the inlet angle of an airfoil positioned at a <NUM>/<NUM> position of the root portion and the tip portion (the position of the second reference airfoil <NUM> of the present disclosure).

The inlet angle of the airfoil of the comparative blade may be <NUM>°, and a noise resultant value may be measured by setting the inlet angle of the airfoil of the comparative blade as a comparison group and the inlet angle θ5 of the second reference airfoil <NUM> as an experiment group.

The noise resultant value is a value obtained by measuring decibel dB when an air volume is 10CMM.

According to Table <NUM>, the inlet angle θ5 of the second reference airfoil <NUM> exceeds <NUM>° and is <NUM>° or less, the noise resultant value may be lowest as <NUM>.

The inlet angle θ5 of the second reference airfoil <NUM> may have a value that exceeds <NUM>° and is <NUM>° or less.

When the inlet angle θ5 of the second reference airfoil <NUM> has a larger value, noise has tendency of decreasing.

However, other factors such as the area, the thickness, the length, etc. of the blade complexly influence noise, so when the inlet angle θ5 of the second reference airfoil <NUM> exceeds <NUM>°, noise has tendency of increasing again.

The first reference airfoil <NUM> may be an airfoil at a <NUM>/<NUM> position of the root portion <NUM> and the tip portion <NUM>, and the second reference airfoil <NUM> may be an airfoil at a <NUM>/<NUM> position of the root portion <NUM> and the tip portion <NUM>.

The blade <NUM> may be designed on the basis of the first inlet angle θ4 of the first reference airfoil <NUM> and the second inlet angle θ5 of the second reference airfoil <NUM>.

In the blade <NUM>, an optimal inlet angle may be primarily selected on the basis of the second inlet angle θ5 and then the first inlet angle θ4 may be selected through a <NUM>-factor <NUM>-level experiment.

It is possible to calculate the second inlet angle θ5 at which noise least generated by performing an experiment on the second inlet angle θ5 of the second reference airfoil <NUM> and it is possible to perform an optimal experiment while changing the first inlet angle θ4 with the second inlet angle θ5 obtained.

The optimal experiment may be performed on the decibel dB measured when the air volume is 3CMM.

In order to calculate optimal first inlet angle θ4 and second inlet angle <NUM>, an experiment may be performed on the basis of the case in which the comparative target inlet angle at a <NUM>/<NUM> position of the root portion and the tip portion of the comparative blade is around <NUM>° and the comparative target inlet angle at a <NUM>/<NUM> position of the root portion and the tip portion is around <NUM>°.

It is possible to calculate an optimal value while changing the second inlet angle θ5 on the basis of the case in which the comparative target inlet angle at a <NUM>/<NUM> position of the root portion and the tip portion is <NUM>°. The optimal second inlet angle θ5 primarily selected may exceed <NUM>° and may be <NUM>° or less, depending on experiments.

Thereafter, in order to select first inlet angle θ4 and second inlet angle <NUM>, an experiment may be performed on the basis <NUM>° that is the comparative target inlet angle at a <NUM>/<NUM> position of the root portion and the tip portion of the comparative blade and <NUM>° that is one of the selected optimal second inlet angles θ5.

In detail, it is possible to measure a noise resultant value y while changing the sizes of the first inlet angle θ4 and the second inlet angle θ5 on the basis of points at which the first inlet angle θ4 and the second inlet angle θ5 are <NUM>° and <NUM>°.

Table <NUM> shows the results of experiments performed on a first inlet angle θ4 and a second inlet angle θ5 in the way described above.

According to the experiment results, when the first inlet angle θ4 is smaller than a set reference, the noise shows only tendency of increasing. However, when the first inlet angle θ4 is larger than the set reference, the noise is influenced by the second inlet angle θ5.

According to the experiment results, the optimal first inlet angle θ4 may exceed <NUM>° and may be <NUM>° or less and the second inlet angle θ5 may exceed <NUM>° and may be <NUM>° or less.

When the first inlet angle θ4 exceeds <NUM>° and is <NUM>° or less and the second inlet angle θ5 exceeds <NUM>° and is <NUM>° or less, the noise resultant value y is <NUM>.

Referring to <FIG>, noise resultant values measured by repeating experiments in the way described above can be seen through a contour line.

According to <FIG>, the first inlet angle θ4 and the second inlet angle θ5 corresponding to a region in which noise decreases to <NUM>. 4dB or less may be appropriate values for noise reduction.

The region in which noise decreases to <NUM>. 4dB or less may be a section smoothly connecting three points at which the first inlet angle θ4 and the second inlet angle θ5 are (<NUM>°, <NUM>°), (<NUM>°, <NUM>°), and (<NUM>°, <NUM>°).

An optimal region R having the lowest noise value in the region in which noise decreases to <NUM>. 4dB or less may be composed of a log function connecting two points at which the first inlet angle θ4 and the second inlet angle θ5 are <NUM>°,<NUM>) and (<NUM>°<NUM>°), a straight line connecting two points of (<NUM>°,<NUM>) and (<NUM>°,<NUM>), and a straight line connecting two points of (<NUM>°,<NUM>) and (<NUM>°,<NUM>°).

Hereafter, a fan <NUM> according to another embodiment of the present disclosure is described with reference to <FIG> is a perspective view of a fan <NUM> according to another embodiment of the present disclosure.

The fan <NUM> may include: a hub <NUM> connected with a motor shaft <NUM>; a shroud <NUM> disposed to be spaced apart from the hub <NUM>; a plurality of blades <NUM> connecting the hub <NUM> and the shroud <NUM>; and notches <NUM> formed at the plurality of blades <NUM>.

The fan <NUM> is rotated in the circumferential direction about a rotation axis RX.

The shroud <NUM> may include a rim portion <NUM> extending in the circumferential direction and a supporting portion <NUM> extending to be inclined from the rim portion <NUM>.

The hub <NUM> may include a first hub surface <NUM> that guides a flow direction of air suctioned in the fan <NUM>.

In the fan <NUM> according to another embodiment of the present disclosure, the hub <NUM> and the shroud <NUM> are the same as the hub <NUM> and the shroud <NUM> according to an embodiment of the present disclosure, so detailed description is omitted.

Hereafter, the notch <NUM> is described with reference to <FIG>. <FIG> is a view enlarging the blade <NUM>, <FIG> is a view of the blade <NUM> cut along line F-F' shown in <FIG>, and <FIG> is a view showing flow of air by the notch <NUM>. Hereafter, the up-down direction is based on the direction shown in <FIG> in the description of the notch <NUM>.

The blade <NUM> may include: a leading edge <NUM> forming one side of the blade <NUM>; a trailing edge <NUM> facing the leading edge <NUM>; a negative pressure surface <NUM> connecting the upper end of the leading edge <NUM> and the upper end of the trailing edge <NUM>; and a pressure surface <NUM> connecting the lower end of the leading edge <NUM> and the lower end of the trailing edge <NUM> and facing the negative pressure surface <NUM>.

In the fan <NUM> according to another embodiment of the present disclosure, the description of the pressure surface <NUM>, the negative pressure surface <NUM>, the leading edge <NUM>, and the trailing edge <NUM> according to an embodiment of the present disclosure may be applied in the same way to the description of the pressure surface <NUM>, the negative pressure surface <NUM>, the leading edge <NUM>, and the trailing edge <NUM> except the description of the notch <NUM>.

A plurality of notches <NUM> may be formed at each of a plurality of blades <NUM> to reduce noise generated at the fan and sharpness of the noise
The notch <NUM> may be formed at a portion of the leading edge <NUM> and a portion of the negative pressure surface <NUM>. The notch <NUM> may be formed by recessing downward a corner <NUM> at which the leading edge <NUM> and the negative pressure surface <NUM> meet. The notch <NUM> may be formed at the middle-upper end portion of the leading edge <NUM> and a partial region adjacent to the leading edge <NUM> of the negative pressure surface <NUM>.

The notch <NUM> may be formed to be recessed toward the pressure surface <NUM> from the negative pressure surface <NUM>.

The cross-sectional shape of the notch <NUM> is not limited and may have various shapes. However, it is preferable that the cross-sectional shape of the notch <NUM> has a U-shape or a V-shape to reduce efficiency and noise of the fan <NUM>. The shape of the notch <NUM> will be described below.

The width W of the notch <NUM> may expand upward from the lower portion. The width W of the notch <NUM> may expand upward gradually or step by step.

The width W of the notch <NUM> may narrow toward the pressure surface <NUM>. The width W of the notch <NUM> may expand toward the negative pressure surface <NUM>.

In the notch <NUM>, the same cross-sectional shape may extend in the radial direction.

The notch <NUM> may have a curved line shape and the same cross-sectional shape may extend in the circumferential direction in the notch <NUM>.

The cross-sectional shape of the notch <NUM> may be a V-shape.

The notch <NUM> may include: a first inclined surface <NUM>; a second inclined surface <NUM> facing the first inclined surface <NUM>; and a bottom line <NUM> to which the first inclined surface <NUM> and the second inclined surface <NUM> are connected.

The spacing distance between the first inclined surface <NUM> and the second inclined surface <NUM> may increase toward one direction. The spacing distance between the first inclined surface <NUM> and the second inclined surface <NUM> may increase gradually or step by step. The first inclined surface <NUM> and the second inclined surface <NUM> may be flat surfaces or curved surfaces. The first inclined surface <NUM> and the second inclined surface <NUM> may be triangular shapes.

Three notches <NUM> may be formed. The notches <NUM> may include a first notch 640a, a second notch 640b positioned farther from the hub <NUM> than the first notch 640a, and a third notch 640c positioned farther from the hub <NUM> than the second notch 640b. The gaps NG between the notches <NUM> may be <NUM> to <NUM>. The gaps NG between the notches <NUM> may be larger that the depth ND of the notches <NUM> and the width W of the notches <NUM>.

The leading edge <NUM> may be divided into a first area A1 adjacent to the hub <NUM> from an edge center line CP passing through the center of the leading edge <NUM> and a second area A2 adjacent to the shroud <NUM>, and two of the three notches <NUM> may be positioned in the first area A1 and the other notch <NUM> may be positioned in the second area A2.

The first notch 640a and the second notch 640b may be positioned in the first area A1 and the third notch <NUM> may be positioned in the second area A2. A first distance HG1 of the first notch 640a spaced apart from the hub <NUM> may be <NUM>% to <NUM>% of the length of the leading edge <NUM>, a second distance HG2 of the second notch 640b spaced apart from the hub <NUM> may be <NUM>% to <NUM>% of the length of the leading edge <NUM>, and a third distance HG3 of the third notch 640c spaced apart from the hub <NUM> may be <NUM>% to <NUM>% of the length of the leading edge <NUM>.

The length NL of each of the plurality of notches 640a, 640b, and 640c may be formed to be different. As the plurality of notches 640a, 640b, and 640c are far from the hub <NUM>, the length NL may be increased. The length of the third notch 640c may be longer than the length of the second notch 640b, and the length of the second notch 640b may be longer than the length of the first notch 640a.

It is possible to reduce flow separation that is generated at the blade <NUM> of the fan <NUM> through the shape, the disposition, and the number of the notches <NUM> described above, and as a result, it is possible to reduce noise that is generated at the fan <NUM>.

The bottom line <NUM> may extend in the direction of a tangential line of a certain circumference formed around a rotation axis RX. The bottom line <NUM> may extend along a certain circumference formed around the rotation axis RX. The bottom line <NUM> may form an arch shape around the rotation axis RX. The bottom line <NUM> may extend in an arch shape on a horizontal surface perpendicular to the rotation axis RX.

The bottom line <NUM> may extend by a length the same as the length NL of the notch <NUM>. The extension direction of the bottom line <NUM> may be the extension direction of the notch <NUM>. The extension direction of the bottom line <NUM> ay be a direction for reducing flow separation that is generated at the leading edge <NUM> and the negative pressure surface <NUM> and for reducing resistance of air.

The bottom line <NUM> may have a slope of <NUM> degree to <NUM> degrees with respect to the horizontal surface perpendicular to the rotation axis RX. Preferably, the bottom line <NUM> may be formed in parallel with the horizontal surface perpendicular to the rotation axis RX. Accordingly, it is possible to reduce flow resistance according to rotation of the blade <NUM> by the notch <NUM>.

The depth ND of the notch <NUM> may decrease as the depth ND goes far away from the corner <NUM>. The depth ND of the notch <NUM> may be the highest at the corner <NUM> and may decrease as the depth ND goes far away from the corner <NUM>.

The length NL of the bottom line <NUM> may be longer than the height BW of the leading edge <NUM>. This is because when the length NL of the bottom line <NUM> is too short, flow separation that is generated at the negative pressure surface <NUM> cannot be reduced, and when the length NL of the bottom line <NUM> is too long, the efficiency of the fan is deteriorated.

The length NL of the notch <NUM> (the length NL of the bottom line <NUM>) may be larger that the depth ND of the notches <NUM> and the width W of the notches <NUM>. Preferably, the length NL of the notch <NUM> may be <NUM> to <NUM>, the depth ND of the notch <NUM> may be <NUM> to <NUM>, and the width W of the notch <NUM> may be <NUM> to <NUM>.

The length NL of the notch <NUM> may be <NUM> times to <NUM> times the depth of the notch ND and the length NL of the notch <NUM> may be <NUM> times to <NUM> times the width W of the notch <NUM>.

A start point SP of thee bottom line <NUM> may be positioned at the leading edge <NUM> and an end point EP of the bottom line <NUM> may be positioned at the negative pressure surface <NUM>. The position of the start point SP of the bottom line <NUM> at the leading edge <NUM> may be the medium height of the leading edge <NUM>.

A first spacing distance BD1 between the start point SP and the corner <NUM> may be smaller than a second spacing distance BD2 between the end point EP and the corner <NUM>.

It is preferable that the position of the end point EP may be formed between a <NUM>/<NUM> position to <NUM>/<NUM> position of the entire length of the negative pressure surface <NUM>.

A first notch angle θ6 made by the bottom line <NUM> and the negative pressure surface <NUM> may be smaller than a second notch angle θ7 made by the bottom line <NUM> and the leading edge <NUM>.

Referring to <FIG>, a portion of the air passing through the leading edge <NUM> may guide the other air to flow over the negative pressure surface <NUM> of the blade <NUM> by generating a turbulent flow at the notch <NUM>. Further, the air passing through the leading edge <NUM> does not generate friction by directly coming in contact with the surface of the blade <NUM> due to the turbulent flow formed at the notch <NUM>, so it is possible to suppress flow separation and reduce noise that is generated at the blade <NUM>.

Hereafter, an operation effect on sharpness and noise of the fan <NUM> according to another embodiment of the present disclosure is described with reference to <FIG> and <FIG>. <FIG> is a graph showing a reduction effect of sharpness by the notch <NUM> and <FIG> is a graph showing a reduction effect of noise by the notch <NUM>.

Referring to <FIG>, it can be seen that the sharpness of the fan <NUM> having the notches <NUM> according to an embodiment of the present disclosure is formed less than the sharpness of a fan not having notches <NUM> according to a comparative example. It can be seen that when the air volumes are the same, flow separation at the leading edge <NUM> is suppressed because the fan <NUM> having the notches <NUM> according to an embodiment of the present disclosure has small sharpness in comparison to the comparative example.

Referring to <FIG>, it can be seen that noise of the fan <NUM> having the notches <NUM> according to an embodiment of the present disclosure is formed less than noise of a fan not having notches <NUM> according to a comparative example. It can be seen that when the air volumes are the same, it is possible to increase blowing performance and reduce noise because the fan <NUM> having the notches <NUM> according to an embodiment of the present disclosure has small noise in comparison to the comparative example.

Hereafter, a fan <NUM> according to another embodiment of the present disclosure is described with reference to <FIG> shows the shape of the fan <NUM> having notches <NUM>.

The fan <NUM> according to another embodiment of the present disclosure may include: a hub <NUM>; a shroud <NUM>; and blades <NUM> at each of which a positive pressure surface <NUM>, a negative pressure surface <NUM>, and a leading edge <NUM> are formed. The hub <NUM> and the shroud <NUM> are the same as the hub <NUM> and the shroud <NUM> of the fan according to an embodiment of the present disclosure, so detailed description is omitted.

A plurality of notches <NUM> formed to be recessed along the negative pressure surface <NUM> from the leading edge <NUM> may be formed at the blade <NUM>.

The entire shape and the design structure of the blade are the same as the blade <NUM> of the fan <NUM> according to an embodiment of the present disclosure, and the shape and the design structure of the notch <NUM> are the same as the notch <NUM> of the fan <NUM> according to another embodiment of the present disclosure, so detailed description is omitted.

Hereafter, the diffuser <NUM> of the fan assembly <NUM> is described with reference to <FIG> and <FIG>. <FIG> a projection view showing a portion of the fan assembly <NUM> longitudinally cut and <FIG> is a view enlarging the diffuser <NUM>.

The fan assembly <NUM> may include a fan housing <NUM> that is open on the upper side and the lower side and in which the motor housing <NUM> is disposed to be spaced.

The diffuser <NUM> may be disposed between the fan housing <NUM> and the motor housing <NUM>. The diffuser <NUM> may connect the fan housing <NUM> and the motor housing <NUM>. A plurality of diffusers <NUM> may be disposed to be spaced apart from each other in the circumferential direction.

At least a portion of the diffuser <NUM> may be disposed between the hub upper end 510b and the shroud edge 520b in the radial direction. An inner edge <NUM> that will be described below may be positioned outside further than the hub upper end 510b in the radial direction and may be positioned inside further than the shroud edge 520b in the radial direction.

The diffuser <NUM> may extend to be inclined in the up-down direction and may be formed in an airfoil shape.

The diffuser <NUM> may guide air radially discharged from the fans <NUM>, <NUM>, and <NUM> to flow upward.

The diffuser <NUM> may include an outer edge <NUM> connected to the fan housing <NUM>, an inner edge <NUM> connected to the motor housing <NUM>, an upper edge <NUM> connecting upper portions of the outer edge <NUM> and the inner edge <NUM>, a lower edge <NUM> connecting lower portions of the outer edge <NUM> and the inner edge <NUM>, a first diffuser surface <NUM> extending up and down between the upper edge <NUM> and the lower edge <NUM>, and a second diffuser surface <NUM> extending up and down between the upper edge <NUM> and the lower edge <NUM> and facing the first diffuser surface <NUM>.

The first diffuser surface <NUM> and the second diffuser surface <NUM> each may be formed as a curved surface.

The first diffuser surface <NUM> may be formed to be connected with the outer edge <NUM>, the inner edge <NUM>, the upper edge <NUM>, and the lower edge <NUM> and to face a side. The second diffuser surface <NUM> may be formed to be connected with the outer edge <NUM>, the inner edge <NUM>, the upper edge <NUM>, and the lower edge <NUM> and to face a direction opposite to the first diffuser surface <NUM>.

The first diffuser surface <NUM> of a plurality of diffusers <NUM> may face the second diffuser surface <NUM> of an adjacent diffuser <NUM>. The second diffuser surface <NUM> of a plurality of diffusers <NUM> may face the first diffuser surface <NUM> of an adjacent diffuser <NUM>.

The first diffuser surface <NUM> may be formed as a continuous curved surface and a plurality of diffuser grooves 446a may be formed at the second diffuser surface <NUM>. The diffuser grooves 446a may extend in the up-down direction and may be formed to be recessed toward the first diffuser surface <NUM> from the second diffuser surface <NUM>. The plurality of diffuser grooves 446a may be formed to be spaced apart from each other in the horizontal direction.

A rib <NUM> protruding from the second diffuser surface <NUM> may be formed between the plurality of diffuser grooves 446a. The diffuser grooves 446a may be formed by being recessed between a plurality of ribs <NUM>.

The diffuser groove 446a may extend from a medium height of the second diffuser surface <NUM> to the lower edge <NUM>.

The diffuser groove 446a may be formed to be concave toward the first diffuser surface <NUM> from the second diffuser surface <NUM>.

A groove upper end 446c of the diffuser groove 446a may be positioned lower than the upper edge <NUM> and a groove lower end 446d may be positioned to be in contact with the lower edge <NUM>. The groove upper ends 446c of the plurality of diffuser grooves 446a may be positioned on the same horizontal surface. A plurality of groove lower ends 446d may be formed in an arc shape along the lower edge <NUM>.

The diffuser groove 446a may be formed to be bent at least one time in the up-down direction. A bending portion 440b that will be described below may be formed at the second diffuser surface <NUM> and the diffuser groove 446a may be formed to be bent at a position corresponding to the bending portion 440b.

The upper edge <NUM> may horizontally extend. When the upper edge <NUM> horizontally extends, the upper edge <NUM> effectively guides upward air discharged through the fans <NUM>, <NUM>, and <NUM>, so ascending airflow may be formed.

The lower edge <NUM> may be formed in a curved surface shape. The lower edge <NUM> may be formed in a curved surface shape formed to be concavely upward from the lower side. The lower edge <NUM> may be formed to be concave toward the upper edge <NUM>. The shape of the lower edge <NUM> may be an arc shape. The lower edge <NUM> may form a concave lower end of the diffuser <NUM>.

The lower edge <NUM> may connect the outer edge <NUM> and the inner edge <NUM>. Both ends of the lower edge <NUM> that are connected to the outer edge <NUM> and the inner edge <NUM>, respectively, may be positioned at the same height.

When the lower edge <NUM> is formed in a straight surface shape, in comparison to a curved surface shape, relatively large flow resistance is generated in the air discharged from the fans <NUM>, <NUM>, and <NUM>, and blowing performance is reduced and noise is generated by the generated flow resistance.

By forming the lower edge <NUM> in an arc shape, it is possible to minimize flow resistance acting in the air discharged from the fans <NUM>, <NUM>, and <NUM>, and it is possible to reduce operation noise.

By forming the lower edge <NUM> in an arc shape, it is possible to increase the air volume and air pressure of air that is supplied to the first tower <NUM> and the second tower <NUM>.

The length between the upper edge <NUM> and the lower edge <NUM> is defined as a first diffuser length DL1.

A maximum spacing length between a virtual horizontal line, which connecting a first lower point 441a constituting the lowermost side of the outer edge <NUM> and a second lower point 442a constituting the lowermost side of the inner edge <NUM>, and the lower edge <NUM> is defined as a second diffuser length DL2.

The second diffuser length DL2 may be formed as <NUM>% to <NUM>% of the first diffuser length DL1. The first diffuser length DL1 may be <NUM> and the second diffuser length DL2 may be <NUM> that is <NUM>% of the first diffuser length DL1.

The diffuser <NUM> may be formed to be curved in the up-down direction. The diffuser <NUM> may include: a first extending portion 440a extending downward from the upper edge <NUM>; a second extending portion 440c extending upward from the lower edge <NUM>; and a bending portion 440b connecting the first extending portion 440a and the second extending portion 440c.

The first diffuser surface <NUM> may extend to have distribution of a radius of curvature that is continuous in the up-down direction. The second diffuser surface <NUM> may extend to have distribution of a radius of curvature that is discontinuous in the up-down direction, and the radius of curvature may be discontinuous at the bending portion 440b.

The lower edge <NUM> may be formed lower than the bending portion 440b and may have an arc shape under the bending portion 440b.

The up-down gap between the first lower point 441a and the bending portion 440b may be larger than the second diffuser length DL2. The up-down gap between the second lower point 442a and the bending portion 440b may be larger than the second diffuser length DL2.

Hereafter, an operation effect of the diffuser <NUM> on an air volume and noise is described with reference to <FIG> and <FIG>. <FIG> is a graph comparing an air volume with an RPM in a comparative example, <FIG> is a graph comparing an air volume with noise in a comparative example, <FIG> is a graph showing noise according to a frequency in a comparative example, and <FIG> is a graph showing noise according to a frequency in an embodiment of the present disclosure.

In the lower end shape of a diffuser is horizontally formed in a comparison target fan, and the shape of the lower edge <NUM> of the diffuser <NUM> is an arc shape in a fan according to the embodiment.

Referring to <FIG> it can be seen that as the number of revolutions of the fan increases, the air volume increases, and there is little different between the comparison target and the embodiment.

Referring to <FIG> and Table <NUM>, it can be seen that as the air volume of the fan increases, noise increases, and it can be seen that when the same air volume is given, the diffuser according to the embodiment reduces noise by <NUM>. 1dB in comparison to the comparison target.

<FIG> is a noise graph according to a diffuser having a flat lower end in the related art <FIG> is a noise graph according to a diffuser having an arc-shaped lower end as in an embodiment of the present disclosure. BPF (Blade Passing Frequency) is a blade passing frequency and is peaking noise that is harmonically generated at specific frequencies in rotation. BPF is a general technique for those skilled in the art, so detailed description is omitted.

Referring to <FIG> and Table <NUM>, the diffuser according to the embodiment can reduce noise of <NUM>. 6dB in comparison to the comparison target at the primary BPF.

Claim 1:
A blower (<NUM>) comprising:
a lower case (<NUM>) in which a suction hole (<NUM>) through which air flows inside is formed;
an upper case (<NUM>, <NUM>) that is disposed on the lower case (<NUM>) and in which a discharge hole (<NUM>, <NUM>) through which air is discharged is formed; and
a fan motor (<NUM>) that provides rotational force; and
a fan (<NUM>) that is disposed in the lower case (<NUM>) and is fixed to a motor shaft (<NUM>) of the fan motor, wherein the motor shaft (<NUM>) forms a rotation axis (MX),
wherein the fan (<NUM>) includes:
a hub (<NUM>) having an outer surface (<NUM>) extending to be inclined at a first angle (θ8) with respect to a first axis (MX1) that is parallel with the rotation axis (MX), and having a hub upper end (510b) located at radial outer end of the hub (<NUM>);
a plurality of blades (<NUM>) coupled to the hub (<NUM>); and
a shroud (<NUM>) having an inner surface facing the outer surface (<NUM>) of the hub (<NUM>) with the blade (<NUM>) therebetween, wherein the shroud (<NUM>) includes:
a rim portion (<NUM>) extending in a circumferential direction into which air is suctioned; and
a supporting portion (<NUM>) extending outward in a radial direction from the rim portion (<NUM>) and extending to be inclined at a second angle (θ9), which is larger than the first angle (θ8), with respect to a second axis (MX2) that is parallel with the rotation axis (MX) and passes through the rim portion (<NUM>), and
wherein the hub upper end (510b) and the rim portion (<NUM>) are aligned on the second axis (MX2).