[0001] The present invention relates to a propeller fan which reduces the magnitude of blowing
noise and prevents occurrence of unpleasant noise, and an air conditioner including
the same.
[0002] An air conditioner is a device that keeps indoor air comfortable so as to be suitable
for human activities using a refrigerating cycle. The air conditioner may cool a room
by repeatedly performing an operation to suck indoor hot air to be heat-exchanged
with a low-temperature refrigerant and then discharge the sucked air into the room,
or heat the room by repeatedly performing its reverse operation.
[0003] The air conditioner may cool or heat the room by a refrigerating cycle in which a
refrigerant is circulated by a compressor, a condenser, an expansion valve, and an
evaporator in either a forward or reverse direction.
[0004] The compressor provides a high-temperature high-pressure gaseous refrigerant, and
the condenser provides a normal-temperature high-pressure liquid refrigerant. The
expansion valve decompresses the normal-temperature high-pressure liquid refrigerant,
and the evaporator evaporates the decompressed refrigerant in a low-temperature gas
state.
[0005] The air conditioner may be classified into a separate type air conditioner in which
an outdoor unit and an indoor unit are separately installed and an integrated air
conditioner in which the outdoor unit and the indoor unit are integrally installed.
In the case of the separate type air conditioner in which the outdoor unit and the
indoor unit are separately installed, a compressor for compressing a refrigerant and
a condenser (outdoor heat exchanger) are generally provided in the outdoor unit, and
an evaporator (indoor heat exchanger) is provided in the indoor unit. The refrigerant
can flow while circulating the outdoor unit and the indoor unit through a piping connecting
the outdoor unit and the indoor unit.
[0006] The outdoor unit of the separate type air conditioner includes a compressor, a condenser,
a blowing fan, a driving motor for rotating the blowing fan, and the like. The driving
motor may condense a refrigerant to a liquid refrigerant through heat-exchange with
a gaseous refrigerant flowing inside the condenser of the outdoor unit by rotating
the blowing fan, and then discharge the condensed refrigerant to the outside of the
outdoor unit.
[0007] As the blowing fan of the outdoor unit, a propeller fan may be used. The propeller
fan is one axial-flow fan which includes a cylindrical hub to which a rotating shaft
of the driving motor is coupled and a plurality of blades extending to the outside
of the hub so as to form a flow of air in the axial direction. Such a propeller fan
may be used in the outdoor unit of the air conditioner and the like to cause air to
forcibly flow by a pressure difference before and behind the propeller fan.
[0008] Therefore, it is an aspect of the present invention to provide a propeller fan which
may reduce the magnitude of blowing noise by improving a structure of the propeller
fan and prevent occurrence of unpleasant noise to improve quality of the noise, and
an air conditioner including the same.
[0009] Additional aspects of the present inventionwill be set forth in part in the description
which follows, and in part, will be apparent from the description, or may be learned
by practice of the invention.
[0010] In accordance with one aspect of the present invention, an air conditioner includes:
an outdoor unit that includes a compressor configured to compress a refrigerant, a
condenser configured to condense the compressed refrigerant, and a blowing fan configured
to blow outdoor air into the outdoor unit; an indoor unit that discharges air heat-exchanged
with the refrigerant flowing-in from the outdoor unit to a room; and a connection
piping that connects the outdoor unit and the indoor unit. Here, the blowing fan may
include a plurality of blades, a plurality of protrusions may be formed on both sides
of facing edges of the blade, and a convex portion and a concave portion may be formed
on a surface of the blowing fan so that the surface of the blowing fan is indented.
[0011] The blowing fan may include a hub fixed to a shaft of a driving motor and the plurality
of blades arranged along a circumference of the hub.
[0012] The blade may include a trailing edge and a leading edge that leads the trailing
edge when rotated with respect to the hub, and the plurality of protrusions may be
formed so as to protrude from both sides of the leading edge and the trailing edge.
[0013] The protrusion may be formed so as to protrude forward of the leading edge.
[0014] The protrusion may be formed so as to protrude backward of the trailing edge.
[0015] The plurality of protrusions may be formed on the leading edge, and the plurality
of protrusions may be formed on the trailing edge so as to correspond to the protrusions
formed on the leading edge.
[0016] The convex portion may be formed so as to connect the protrusions formed on the leading
edge and the trailing edge.
[0017] The concave portion may be formed between the convex portions adjacent to each other.
[0018] The protrusion may be formed in a range of 1.3% to 6.6% of a length of the blade.
[0019] The protrusion may be formed in a range of 0.3 mm or more to 27 mm or less.
[0020] A height of the convex portion may be formed in a range of 0.5% to 6.0% of a length
of the blade.
[0021] The height of the convex portion may be formed in a range of 2 mm or more to 18 mm
or less.
[0022] The number of the formed protrusions may be at least three.
[0023] In accordance with another aspect of the present invention, a propeller fan includes:
a hub connected to a driving motor to receive a rotational force; and a plurality
of blades radially arranged on a circumference of the hub. Here, a surface of the
blade may be indented, and a plurality of protrusions may be formed on a leading edge
and a trailing edge of the blade.
[0024] The plurality of protrusions may be formed to have irregular sizes.
[0025] A convex portion may be formed on the surface of the blade so as to connect the protrusions
formed on the leading edge and the protrusions formed on the trailing edge so as to
correspond to the protrusions of the leading edge.
[0026] The number of the convex portions may be plural, and a height of the convex portion
may be irregularly formed.
[0027] A protruding length of the protrusion may be formed in a range of 1.3% to 6.6% of
a length of the blade.
[0028] A height of the convex portion may be formed in a range of 0.5% to 6.0% of a length
of the blade.
[0029] The blade may be formed to be inclined so as to blow air from a rear side of the
blade toward a front side thereof along an axial direction of the hub.
[0030] These and/or other aspects of the invention will become apparent and more readily
appreciated from the following description of the embodiments, taken in conjunction
with the accompanying drawings of which:
FIG. 1 illustrates an air conditioner in accordance with one embodiment of the present
invention;
FIG. 2 is a front view illustrating a propeller fan in accordance with one embodiment
of the present invention;
FIG. 3 is a side view illustrating a propeller fan in accordance with one embodiment
of the present invention;
FIG. 4 is a front enlarged view illustrating a portion of a propeller fan in accordance
with one embodiment of the present invention;
FIG. 5 is a cross-sectional view illustrating a propeller fan in accordance with one
embodiment of the present invention;
FIG. 6 are a graph showing the magnitude of noise in accordance with air flow of a
propeller fan in accordance with one embodiment of the present invention; and
FIGS. 7 and 8 are graphs showing a frequency of noise due to rotation of a propeller
fan in accordance with one embodiment of the present invention and a frequency of
noise due to rotation of a conventional propeller fan.
[0031] Reference will now be made in detail to the embodiments of the present invention,
examples of which are illustrated in the accompanying drawings, wherein like reference
numerals refer to like elements throughout.
[0032] Hereinafter, a propeller fan in accordance with one embodiment of the present invention
and an air conditioner including the propeller fan will be described in detail with
reference to the accompanying drawings.
[0033] FIG. 1 illustrates an air conditioner in accordance with one embodiment of the present
invention.
[0034] Referring to FIG. 1, an air conditioner in accordance with one embodiment of the
present invention includes an indoor unit 1 and an outdoor unit 2. The indoor unit
1 and the outdoor unit 2 may be connected by a refrigerant piping 3. The refrigerant
piping 3 may include refrigerant pipes 31, 32 which deliver gaseous refrigerant and
condensed refrigerant to the outdoor unit and indoor unit, respectively. A refrigerant
may circulate in a refrigerant pipe (not shown) provided in the indoor unit 1 and
a refrigerant pipe (not shown) provided in the outdoor unit 2 through the refrigerant
piping 3.
[0035] The indoor unit 1 may discharge air heat-exchanged with the refrigerant which has
been compressed and condensed in the outdoor unit 2 into a room, and therefore a room
temperature can be maintained at an appropriate temperature. The indoor unit 1 may
include an expansion valve and an evaporator. The air in the room may be cooled by
the refrigerant evaporated in the evaporator.
[0036] The outdoor unit 2 may include a compressor, a condenser, and a blowing fan 20. An
air flow inlet through which outdoor air can flow into or out of the outdoor unit
2 may be formed on one side of the outdoor unit 2. The refrigerant is compressed by
the compressor and the compressed refrigerant flows into the condenser to be condensed.
In this instance, the blowing fan 20 is driven, and the outdoor air flowing in through
the air flow inlet may cool heat generated in the condenser.
[0037] The blowing fan 20 provided in the outdoor unit 2 may be a propeller fan which is
a kind of axial flow fan. Hereinafter, it is assumed that the blowing fan 20 is provided
as the propeller fan, and a structure of the propeller fan will be described in detail
with reference to the drawings.
[0038] FIG. 2 is a front view illustrating a propeller fan in accordance with one embodiment
of the present invention, and FIG. 3 is a side view illustrating a propeller fan in
accordance with one embodiment of the present invention.
[0039] Referring to FIGS. 2 and 3, a propeller fan 20 in accordance with one embodiment
of the present invention includes a hub 21 and a plurality of blades 22. The plurality
of blades 22 may be radially arranged on a circumference of the hub 21.
[0040] A shaft (not shown) of a driving motor may be connected to the hub 21. The hub 21
is firmly coupled to the shaft (not shown) of the driving motor through a screw fastening
structure or the like to receive a rotational force from the shaft (not shown). Thus,
the propeller fan 20 can be rotated by a driving force of the driving motor.
[0041] The blades 22 may be radially arranged at a constant interval on the circumference
of the hub 21. The plurality of blades 22 may be provided to have the same shape.
The blades 20 are provided to have a gentle inclination so that air behind (A) the
propeller fan 20 can flow to the front (B) of the propeller fan 20 along an axial
direction.
[0042] The blade 22 includes a leading edge 221 and a trailing edge 220. Any one of facing
edges of the blade 22 may be the leading edge 221, and the other thereof may be the
trailing edge 220. When the blade 22 is rotated with respect to the hub 21 in a clockwise
direction, an edge of the blade 22 which leads the trailing edge 220 may be the leading
edge 221 and an edge of the blade 22 which trails may be the trailing edge 220.
[0043] Hereinafter, it is assumed that the leading edge 221 is positioned on a front side
of the blade 22 and the trailing edge 220 is positioned on a rear side thereof.
[0044] The air introduced to the blade 22 through the leading edge 221 flows along a front
surface of the blade 22 and is discharged backward of the trailing edge 220. The blade
22 may be provided to have a gentle inclination so as to be directed backward of the
propeller fan 20 as it goes from the leading edge 221 to the trailing edge 220. Thus,
when the propeller fan 20 is rotated, the air may flow from the rear of the propeller
fan 20 to the front along the axial direction.
[0045] FIG. 4 is a front enlarged view illustrating a portion of a propeller fan in accordance
with one embodiment of the present invention, and FIG. 5 is a cross-sectional view
illustrating a propeller fan in accordance with one embodiment of the present invention.
[0046] Referring to FIGS. 4 and 5, a plurality of protrusions 224 and 225 may be formed
in the blades 22 of the propeller fan 20 in accordance with one embodiment of the
present invention. A surface of the propeller fan 20 may be indented along the circumferential
direction of a circle that forms a concentric circle with the hub 21. The indented
portion formed on the surface of the propeller fan 20 may be provided so as to correspond
to a position where the plurality of protrusions 224 and 225 are formed.
[0047] The plurality of protrusions 224 and 225 may be formed in the leading edge 221 or
the trailing edge 220. The protrusions 224 may be formed so as to protrude forward
of the leading edge 221. The protrusions 225 may be formed so as to protrude backward
of the trailing edge 220. The protrusions 224 formed in the leading edge 221 and the
protrusions 225 formed in the trailing edge 220 may be formed so as to correspond
to each other.
[0048] When a position of the leading edge 221 is assumed to be P in a state in which the
protrusions 224 are not formed, the protrusions 224 may be formed so as to protrude
forward of the blade 22 from P. It may be assumed that a distance between P and the
most protruding portion of the protrusions 224 is L. The size of the protrusion 224
may be increased along an increase in L. This may be applicable in the same manner
as in the case of the trailing edge 220.
[0049] For example, at least three protrusions 224 may be formed in the leading edge 221.
In addition, at least three protrusions 225 may be formed in the trailing edge 220.
The plurality of protrusions 224 formed in the leading edge 221 may have different
sizes and shapes. As an example, the size of the protrusions 224 positioned far away
from the hub 21 may be larger than that of the protrusions 224 positioned adjacent
to the hub 21. The plurality of protrusions may be formed in such a manner that intervals
between the adjacent protrusions are different. This may be applicable in the same
manner as in the case of the protrusions 225 of the trailing edge 220.
[0050] The protruding length (L) of each of the protrusions 224 and 225, and may be designed
in a range of 1.3% to 6.6% of a length (W) of the blade 22. For example, when the
length (W) of the blade is 300 mm, the protruding length (L) of each of the protrusions
224 and 225 may be formed in a range of 4 mm < L < 20 mm.
[0051] The shape, size, and the number of the protrusions 224 are not limited to the above
descriptions and may vary depending on the structure and shape of the propeller fan
20.
[0052] A surface of the blade 22 may be indented along the circumferential direction of
a circle that forms a concentric circle with the hub 21. When viewing the propeller
fan 20 from the front (B), a portion that protrudes to the front (B) may be referred
to as a convex portion 222 and a portion that protrudes to the rear (A) may be referred
to as a concave portion 223. The convex portion 222 and the concave portion 223 may
extend along the circumferential direction of the circle that forms the concentric
circle with the hub 21.
[0053] The convex portion 222 and the concave portion 223 may extend so as to connect the
leading edge 221 and the trailing edge 220. The protrusions may be formed in a corresponding
position of each of the leading edge 221 and the trailing edge 220, and the convex
portion 222 may be formed so as to connect the protrusions 224 formed in the leading
edge 221 and the protrusions 225 formed in the trailing edge 220. The concave portion
223 may be formed between the adjacent convex portions 222.
[0054] When it is assumed that a flat surface of the blade 22 is P in a state in which the
concave portion 223 and the convex portion 222 are not formed on the surface of the
blade 22, a height (H) of any one of the plurality of convex portions 222 and a height
of the adjacent convex portion 222 may be different from each other. As an example,
the height (H) of the convex portion 222 positioned adjacent to the hub 21 or adjacent
to a tip 226 that is an end of the blade 22 may be larger than the height of the convex
portion 222 positioned in a middle portion between the hub 21 and the tip 226.
[0055] This concerning the height of the convex portion 222 may be applicable in the same
manner as in a height (H') of the concave portion 223. When it is assumed that a flat
surface of the blade 22 is P' in a state in which the concave portion 223 and the
convex portion 222 are not formed on the surface of the blade 22, a height (H') of
any one of the plurality of concave portions 223 and a height of the adjacent concave
portion 223 may be different from each other. As an example, the height (H') of the
concave portion 223 positioned adjacent to the hub 21 or adjacent to the tip 226 that
is the end of the blade 22 may be larger than the height of the concave portion 223
positioned in a middle portion between the hub 21 and the tip 226.
[0056] The height (H) of the convex portion 222 may be formed in a range of 0.5% to 6.0%
of the length (W) of the blade 22. In the same manner, the height (H') of the concave
portion 223 may be formed in a range of 0.5% to 6.0% of the length (W) of the blade
22.
[0057] For example, when the length (W) of the blade 22 is 300 mm, the height (H) of the
convex portion 222 or the height (H') of the concave portion 223 may be formed in
a range of 1.5 mm < H (H') < 18 mm.
[0058] The height (H) of the convex portion 222 or the height (H') of the concave portion
223 is not limited to the above descriptions, and the height, the shape, the number
of the convex portions 222 or the concave portions 223 may vary depending on the structure
of the applied propeller fan 20.
[0059] The protrusions 224 of the leading edge 221 and the protrusions 225 of the trailing
edge 220 are formed, and therefore it is possible to prevent occurrence of a large
turbulent flow while the blade 22 is rotated. More specifically, the turbulent flow
due to the rotation of the blade 22 does not occur in the form of a large single turbulent
flow, but occur in the form of small turbulent flows separated by the plurality of
protrusions 224 and 225.
[0060] Since larger noise energy is obtained as the turbulent flow is increased, the turbulent
flow is separated into small turbulent flows, so that noise energy is distributed,
thereby reducing the magnitude of the noise. In addition, the air flows along the
surface of the blade 22 which is indented in the form of waves, and therefore the
magnitude of noise caused by blowing may be reduced and strident noise may be reduced
by reducing the peak frequency of the noise.
[0061] Hereinafter, a noise reduction and an improvement effect of sensible noises in accordance
with the structure of the propeller fan in accordance with one embodiment of the present
invention will be described with reference to the drawings.
[0062] FIG. 6 is a graph showing the magnitude of noise to air flow of a propeller fan in
accordance with one embodiment of the present invention.
[0063] Referring to FIG. 6, it can be seen that there is an effect in which noise at the
time of blowing by the propeller fan 20 in accordance with one embodiment of the present
invention is reduced. Solid line (T) shows the magnitude of noise in accordance with
air flow in the conventional propeller fan in which the protrusions 224 and 225 and
the convex and concave portions 222 and 223 are not formed on the surface of the blade.
Dotted line (F) shows the magnitude of noise in accordance with air flow in the propeller
fan 20 in accordance with one embodiment of the present invention. The conventional
propeller fan and the propeller fan in accordance with one embodiment of the present
invention may have the same diameter, and an experiment is conducted in an environment
in which other external conditions are the same.
[0064] For example, the magnitude ② of noise that occurs when an air flow of the propeller
fan 20 in accordance with one embodiment of the present invention is α m
3/min is reduced by 0.6 dB to 0.8 dB than the magnitude ① of noise that occurs when
an air flow of the conventional propeller fan is α m
3/min. That is, it can be found that, in the case of the same air flow, the magnitude
of the noise generated by the propeller fan 20 in accordance with one embodiment of
the present invention is smaller than the magnitude of the noise generated by the
conventional propeller fan.
[0065] Thus, through the above-described experiment, it can be confirmed that the propeller
fan in accordance with one embodiment of the present invention in which the plurality
of protrusions are formed in the blade and the convex portions and the concave portions
are formed on the surface of the blade may generate less noise compared to the conventional
propeller fan.
[0066] FIGS. 7 and 8 are graphs showing a frequency of noise due to rotation of a propeller
fan in accordance with one embodiment of the present invention (FIG. 7) and a frequency
of noise due to rotation of a conventional propeller fan (FIG. 8). A dotted line on
the graph is a line indicating an audible range.
[0067] It can be seen that, when a frequency position is S in a case in which a rotational
frequency per minute of each of the propeller fan 20 in accordance with one embodiment
of the present invention and the conventional propeller fan is approximately 1kHz,
the number of peak points in which the frequency of the propeller fan 20 in accordance
with one embodiment of the present invention is irregularly shown is small.
[0068] That is, when the propeller fan 20 in accordance with one embodiment of the present
invention is rotated at the same frequency, smaller number of irregular peak points
are generated compared to when the conventional propeller fan is rotated at the same
frequency. As is apparent from the fact that more strident noises occur as the number
of irregular peak points is increased, less unpleasant noises offensive to the ears
are made by the propeller fan 20 in accordance with one embodiment of the present
invention compared to the conventional propeller fan.
[0069] As described above, in the propeller fan 20 in accordance with one embodiment of
the present invention, the plurality of protrusions are formed in the leading edge
221 and trailing edge 220 of the blade 22 and the convex portions 222 and the concave
portions 223 are formed on the surface of the blade 22, and therefore the propeller
fan 20 may have a shape like a whale's fin or flipper. By such a shape, noise that
occurs when the propeller fan 20 is rotated may be reduced, and occurrence of unpleasant
noise may be prevented.
[0070] The structure of the propeller fan has been described above, but when the propeller
fan is applied to an air conditioner, the propeller fan can be referred to as a blowing
fan.
[0071] In accordance with one embodiment of the present invention, by applying features
and advantages of natural objects to the shape of the propeller fan, the magnitude
of noise that occurs due to the rotation of the propeller fan may be reduced, and
quality of a sensible noise may be improved.
[0072] Although a few embodiments of the present invention have been shown and described,
it would be appreciated by those skilled in the art that changes may be made in these
embodiments without departing from the invention, the scope of which is defined in
the claims.
1. An air conditioner comprising:
an outdoor unit that includes a compressor configured to compress a refrigerant, a
condenser configured to condense the compressed refrigerant, and a blowing fan configured
to blow outdoor air into the outdoor unit;
an indoor unit that discharges air heat-exchanged with the refrigerant flowing in
from the outdoor unit to a room; and
a connection piping that connects the outdoor unit and the indoor unit,
wherein the blowing fan includes a plurality of blades, a plurality of protrusions
are formed on both sides of facing edges of the blade, and a convex portion and a
concave portion are formed on a surface of the blowing fan so that the surface of
the blowing fan is indented.
2. The air conditioner according to claim 1, wherein the blowing fan includes a hub fixed
to a shaft of a driving motor and the plurality of blades arranged along a circumference
of the hub.
3. The air conditioner according to claim 2, wherein the blade includes a trailing edge
and a leading edge that leads the trailing edge when rotated with respect to the hub,
and the plurality of protrusions are formed so as to protrude from both sides of the
leading edge and the trailing edge.
4. The air conditioner according to claim 3, wherein the protrusion is formed so as to
protrude forward of the leading edge.
5. The air conditioner according to claim 3, wherein the protrusion is formed so as to
protrude backward of the trailing edge.
6. The air conditioner according to claim 3, wherein the plurality of protrusions are
formed on the leading edge, and the plurality of protrusions are formed on the trailing
edge so as to correspond to the protrusions formed on the leading edge.
7. The air conditioner according to claim 6, wherein the convex portion is formed so
as to connect the protrusions formed on the leading edge and the trailing edge.
8. The air conditioner according to claim 7, wherein the concave portion is formed between
the convex portions adjacent to each other.
9. The air conditioner according to claim 1, wherein the protrusion is formed in a range
of 1.3% to 6.6% of a length of the blade.
10. The air conditioner according to claim 1, wherein a height of the convex portion is
formed in a range of 0.5% to 6.0% of a length of the blade.
11. The air conditioner according to claim 1, wherein the number of the formed protrusions
is at least three.