FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
AXIAL FLOW FAN, AIR-SENDING DEVICE, AND REFRIGERATION CYCLE
APPARATUS;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

2
DESCRIPTION
AXIAL FLOW FAN, AIR-SENDING DEVICE, AND REFRIGERATION CYCLE
APPARATUS
5
Technical Field
[0001]
The present disclosure relates to an axial flow fan including a plurality of blade
each having a trailing edge having an indentation, an air-sending device including the
10 axial flow fan, and a refrigeration cycle apparatus including the air-sending device.
Background Art
[0002]
A conventional axial flow fan includes a plurality of blades along a
circumferential surface of a cylindrical boss, and is configured to convey a fluid with
15 the blades rotating with a rotative force applied to the boss. Rotation of the blades of
the axial flow fan causes a portion of the fluid that is present between the blades to
collide with blade surfaces. The surfaces with which the fluid collides are subjected
to raised pressures, and the fluid is moved by being pressed in a direction of an axis
of rotation serving as a central axis on which the blades rotate.
20 [0003]
Among such axial flow fans, there has been proposed an axial flow fan
provided with a serration portion having serrated projections by providing a trailing
edge with a plurality of triangular indentations, the projections each having a central
portion that is thick in a radial longitudinal section and an edge portion that is thin in
25 the radial longitudinal section (see, for example, Patent Literature 1).
Citation List
Patent Literature
[0004]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
30 11-210691
3
Summary of Invention
Technical Problem
[0005]
The axial flow fan of Patent Literature 1 is supposed to reduce noise generation
5 by generating only small vortices by causing airflows flowing along an outer surface of
a blade to smoothly merge at the serration portion of the trailing edge. However, the
axial flow fan of Patent Literature 1 has a risk that when a centrifugal force entailed by
rotation of the blade causes an airflow to be released at a place off an edge portion at
which an airflow is thin, a strong blade tip vortex may be generated by a slipstream
10 generated at an edge portion at which an airflow is thick.
[0006]
The present disclosure is intended to solve such a problem, and has as an
object to provide an axial flow fan configured to inhibit the growth of a blade tip vortex
at an edge portion, especially at a trailing edge, an air-sending device including the
15 axial flow fan, and a refrigeration cycle apparatus including the air-sending device.
Solution to Problem
[0007]
An axial flow fan according to an embodiment of the present disclosure
includes a hub driven to rotate and configured to serve as a rotation axis of the axial
20 flow fan and a blade connected to the hub. The blade has a leading edge and a
trailing edge. The trailing edge has an indentation indenting toward the leading
edge. The indentation narrows from the trailing edge to the leading edge, and has
an apex being a point closest to the leading edge from among the points constituting
the indentation. The blade has, at the indentation, a maximum thickness portion at
25 which a thickness of the blade is maximum, and which is positioned radially inside of
the apex.
[0008]
An air-sending device according to an embodiment of the present disclosure
includes the axial flow fan thus configured, a drive source configured to apply a drive
30 force to the axial flow fan, and a casing configured to house the axial flow fan and the
4
drive source.
[0009]
A refrigeration cycle apparatus according to an embodiment of the present
disclosure includes the air-sending device thus configured and a refrigerant circuit
5 having a condenser and an evaporator. The air-sending device is configured to send
air to at least either the condenser or the evaporator.
Advantageous Effects of Invention
[0010]
According to the embodiment of the present disclosure, the axial flow fan is
10 configured such that a thickness of a portion of the blade that is positioned inside of
the apex is a maximum thickness. The axial flow fan can reduce a speed difference
in a slipstream generated and inhibit the growth of a blade tip vortex, as the apex, at
which a wind velocity is high, is smaller in blade thickness than the maximum
thickness portion.
15 Brief Description of Drawings
[0011]
[Fig. 1] Fig. 1 is a perspective view schematically showing a configuration of an
axial flow fan according to Embodiment 1.
[Fig. 2] Fig. 2 is a plan view of a blade shown in Fig. 1 as seen from an angle
20 parallel with an axial direction of a rotation axis.
[Fig. 3] Fig. 3 is a side view conceptually showing an example of a distribution
of blade thickness of a trailing edge shown in Fig. 2.
[Fig. 4] Fig. 4 is a diagram showing a blade surface distribution of the trailing
edge of the axial flow fan according to Embodiment 1.
25 [Fig. 5] Fig. 5 is another plan view of a blade shown in Fig. 1 as seen from an
angle parallel with the axial direction of the rotation axis.
[Fig. 6] Fig. 6 is a diagram conceptually showing a shape of a cross-section of
the trailing edge of the blade shown in Fig. 5 as taken along line M-M.
[Fig. 7] Fig. 7 is a diagram conceptually showing a shape of another cross30 section of the trailing edge of the blade shown in Fig. 5 as taken along line M-M.
5
[Fig. 8] Fig. 8 is a diagram conceptually showing a shape of another crosssection of the trailing edge of the blade shown in Fig. 5 as taken along line M-M.
[Fig. 9] Fig. 9 is a plan view of an axial flow fan according to a comparative
example as seen from an angle parallel with an axial direction of a rotation axis.
5 [Fig. 10] Fig. 10 is a side view conceptually showing a distribution of blade
thickness of a trailing edge of a blade shown in Fig. 9.
[Fig. 11] Fig. 11 is a diagram showing a blade surface distribution of the trailing
edge of the axial flow fan according to the comparative example.
[Fig. 12] Fig. 12 is a schematic view showing a relationship between the blade
10 of the axial flow fan according to Embodiment 1 and airflows.
[Fig. 13] Fig. 13 is a plan view of an axial flow fan according to Embodiment 2
as seen from an angle parallel with an axial direction of a rotation axis.
[Fig. 14] Fig. 14 is a side view conceptually showing an example of a
distribution of blade thickness of a trailing edge of a blade shown in Fig. 13.
15 [Fig. 15] Fig. 15 is a diagram showing a blade surface distribution of the trailing
edge of the axial flow fan according to Embodiment 2.
[Fig. 16] Fig. 16 is a plan view of an axial flow fan according to Embodiment 3
as seen from an angle parallel with an axial direction of a rotation axis.
[Fig. 17] Fig. 17 is a side view conceptually showing an example of a
20 distribution of blade thickness of a trailing edge of a blade shown in Fig. 16.
[Fig. 18] Fig. 18 is a diagram showing a blade surface distribution of the trailing
edge of the axial flow fan according to Embodiment 3.
[Fig. 19] Fig. 19 is a plan view of an axial flow fan according to Embodiment 4
as seen from an angle parallel with an axial direction of a rotation axis.
25 [Fig. 20] Fig. 20 is a side view conceptually showing an example of a
distribution of blade thickness of a trailing edge of a blade shown in Fig. 19.
[Fig. 21] Fig. 21 is a diagram showing a blade surface distribution of the trailing
edge of the axial flow fan according to Embodiment 4.
[Fig. 22] Fig. 22 is a plan view of an axial flow fan according to Embodiment 5
30 as seen from an angle parallel with an axial direction of a rotation axis.
6
[Fig. 23] Fig. 23 is an enlarged view conceptually showing blade tip
indentations shown in Fig. 22.
[Fig. 24] Fig. 24 is a plan view of an axial flow fan according to Embodiment 6
as seen from an angle parallel with an axial direction of a rotation axis.
5 [Fig. 25] Fig. 25 is a plan view of an axial flow fan according to Embodiment 7
as seen from an angle parallel with an axial direction of a rotation axis.
[Fig. 26] Fig. 26 is a schematic view of a refrigeration cycle apparatus
according to Embodiment 8.
[Fig. 27] Fig. 27 is a perspective view of an outdoor unit serving as an air10 sending device as seen from an air outlet side.
[Fig. 28] Fig. 28 is a diagram for explaining a configuration of the outdoor unit
from the top.
[Fig. 29] Fig. 29 is a diagram showing a state in which a fan grille has been
removed from the outdoor unit.
15 [Fig. 30] Fig. 30 is a diagram showing an internal configuration of the outdoor
unit with the fan grille, a front panel, or other components removed from the outdoor
unit.
Description of Embodiments
[0012]
20 In the following, an axial flow fan, an air-sending device, and a refrigeration
cycle apparatus according to embodiments are described with reference to the
drawings. In the following drawings including Fig. 1, relative relationships in
dimension between constituent elements, the shapes of the constituent elements, or
other features of the constituent elements may be different from actual ones.
25 Further, constituent elements given identical reference signs in the following drawings
are identical or equivalent to each other, and these reference signs are adhered to
throughout the full text of the description. Further, the directive terms (such as
"upper", "lower", "right", "left", "front", and "back") used as appropriate for ease of
comprehension are merely so written for convenience of explanation, and are not
30 intended to limit the placement or orientation of a device or a component.
7
[0013]
Embodiment 1.
[Axial Flow Fan 100]
Fig. 1 is a perspective view schematically showing a configuration of an axial
5 flow fan 100 according to Embodiment 1. The direction of rotation DR indicated by
an arrow in Fig. 1 indicates the direction of rotation DR of the axial flow fan 100. In
Fig. 1, the solid-white arrow F indicates the direction F in which an airflow flows. In
the direction F in which an airflow flows, a Z1 side of the axial flow fan 100 is an
upstream side of the airflow with respect to the axial flow fan 100, and a Z2 side of
10 the axial flow fan 100 is a downstream side of the airflow with respect to the axial flow
fan 100. That is, the Z1 side is a suction side of air with respect to the axial flow fan
100, and the Z2 side is a blowout side of air with respect to the axial flow fan 100.
Further, the Y axis represents the direction of the radius of the axial flow fan 100 with
respect to the rotation axis RS. A Y2 side of the axial flow fan 100 is an inner
15 peripheral side of the axial flow fan 100, and a Y1 side of the axial flow fan 100 is an
outer peripheral side of the axial flow fan 100.
[0014]
The axial flow fan according to Embodiment 1 is described with reference to
Fig. 1. The axial flow fan 100 is used, for example, in an air-conditioning apparatus,
20 a ventilating apparatus, or other apparatuses. As shown in Fig. 1, the axial flow fan
100 includes a hub 10 provided on the rotation axis RS and a plurality of blades 20
connected to the hub 10.
[0015]
(Hub 10)
25 The hub 10 is driven to rotate and configured to serve as a rotation axis RS of
the axial flow fan 100. The hub 10 rotates on the rotation axis RS. The direction of
rotation DR of the axial flow fan 100 is a counterclockwise direction indicated by an
arrow in Fig. 1. Note, however, that the direction of rotation DR of the axial flow fan
100 is not limited to a counterclockwise direction. For example, by varying the angle
30 of mounting of the blades 20 or the orientation of the blades 20, the axial flow fan 100
8
may be configured to rotate in a clockwise direction. The hub 10 is connected to a
rotation shaft of a drive source such as a motor (not illustrated). The hub 10 may be
configured in the shape of a cylinder or may be configured in the shape of a plate.
The hub 10 is not limited to any particular shape, provided the hub 10 is connected to
5 the rotation shaft of the drive source as mentioned above.
[0016]
(Blade 20)
The plurality of blades 20 are configured to radially extend radially outward
from the hub 10. The plurality of blades 20 are circumferentially placed at spacings
10 from each other. While Embodiment 1 illustrates an aspect in which three blades 20
are provided, any number of blades 20 may be provided.
[0017]
Each of the blades 20 has a leading edge 21, a trailing edge 22, an outer
peripheral edge 23, and an inner peripheral edge 24. The leading edge 21 is placed
15 upstream (Z1 side) in an airflow generated, and is furthest forward in the direction of
rotation DR in the blade 20. That is, the leading edge 21 is placed in front of the
trailing edge 22 in the direction of rotation DR. The trailing edge 22 is placed
downstream (Z2 side) in the airflow generated, and is furthest rearward in the
direction of rotation DR in the blade 20. That is, the trailing edge 22 is placed behind
20 the leading edge 21 in the direction of rotation DR. The axial flow fan 100 has the
leading edge 21 as a blade tip portion facing in the direction of rotation DR of the axial
flow fan 100, and has the trailing edge 22 as a blade tip portion opposite to the
leading edge 21 in the direction of rotation DR.
[0018]
25 The outer peripheral edge 23 is a portion extending back and forth and in an
arc to connect an outermost peripheral portion of the leading edge 21 and an
outermost peripheral portion of the trailing edge 22. The outer peripheral edge 23 is
placed at an end portion of the axial flow fan 100 in the direction of the radius (i.e. a
Y-axis direction). The inner peripheral edge 24 is a portion extending back and forth
30 and in an arc between an innermost peripheral portion of the leading edge 21 and an
9
innermost peripheral portion of the trailing edge 22. The blades 20 have their inner
peripheral edges 24 connected to the outer periphery of the hub 10.
[0019]
The blades 20 are at a predetermined angle of inclination with respect to the
5 rotation axis RS. The blades 20 convey a fluid by pressing gas present between the
blades 20 with blade surfaces as the axial flow fan 100 rotates. A surface of each of
these blade surfaces that is subjected to a pressure raised by pressing the fluid
serves as a pressure surface 25, and a surface behind the pressure surface 25 that is
subjected to a pressure drop serves as a suction surface 26. A surface of each of
10 the blades 20 situated upstream (Z1 side) of the blade 20 with respect to the direction
in which the airflow flows serves as a suction surface 26, and a surface of each of the
blades 20 situated downstream in a Z2 direction) serves as a pressure surface 25.
In Fig. 1, a surface of each of the blades 20 facing toward a viewer who looks at Fig.
1 serves as a pressure surface 25, and a surface of each of the blades 20 facing
15 away from the viewer serves as a suction surface 26.
[0020]
Fig. 2 is a plan view of a blade 20 shown in Fig. 1 as seen from an angle
parallel with an axial direction of the rotation axis RS. In other words, Fig. 2 is a
diagram of the blade 20 as seen in a plane perpendicular to the rotation axis RS. As
20 shown in Fig. 2, the trailing edge 22 of the blade 20 has one indentation 30. The
indentation 30 is near a radially central portion of the trailing edge 22. The
indentation 30 is a first indentation with respect to the after-mentioned second
indentation.
[0021]
25 The indentation 30, which is the first indentation, is a portion at which a wall
constituting the trailing edge 22 indents toward the leading edge 21. Alternatively,
the indentation 30 is a portion at which the wall constituting the trailing edge 22
indents in the direction of rotation DR. In other words, the indentation 30 indents in a
direction opposite to the direction of rotation DR, and is open in a direction opposite to
30 the direction of rotation DR.
10
[0022]
In a plan view of the blade 20 shown in Fig. 1 as seen from an angle parallel
with the axial direction of the rotation axis RS, the indentation 30 is a portion at which
a blade plate of the blade 20 serving as the trailing edge 22 is notched into a U shape
5 or a V shape. That is, the indentation 30 narrows from the trailing edge 22 to the
leading edge 21. The U shape or the V shape is an example of the shape of the
indentation 30 in a plan view, and the shape of the indentation 30 in a plan view is not
limited to the U shape or the V shape.
[0023]
10 The indentation 30 is defined as a portion of the trailing edge 22 that has a
concave shape and extends further forward in the direction of rotation DR than a first
straight line L1 connecting a basal portion 22b of the trailing edge 22 and a trailing
edge end portion 32 of the trailing edge 22. The basal portion 22b is a portion at
which the hub 10 and the trailing edge 22 intersect. The trailing edge end portion 32
15 is the outermost peripheral end portion of the trailing edge 22. Alternatively, the
trailing edge end portion 32 is a portion of the trailing edge 22 that is close to the
outer peripheral edge 23 and projects in a direction opposite to the direction of
rotation of the axial flow fan 100. The trailing edge end portion 32 is positioned
outside of than the after-mentioned apex 33. In a plan view of the blade 20 as seen
20 from an angle parallel with the axial direction of the rotation axis RS, the straight line
L1 intersects the trailing edge 22 at at least one point between the basal portion 22b
and the trailing edge end portion 32.
[0024]
An intersection portion 31 is a point of intersection at which the first straight line
25 L1 and the trailing edge 22 intersect, and is further inward than the trailing edge end
portion 32. The trailing edge end portion 32 is further outward than the intersection
portion 31. The intersection portion 31 is an inner peripheral end portion of the
indentation 30, and the trailing edge end portion 32 is an outer peripheral end portion
of the indentation 30. The indentation 30 is a portion of the trailing edge portion 22
30 that is between the intersection portion 31, which is the inner peripheral end portion of
11
the indentation 30, and the trailing edge end portion 32, which is the outer peripheral
end portion of the indentation 30.
[0025]
A relationship of each position of the indentation 30 in the direction of rotation
5 DR is discussed here in terms of a relationship between a point of intersection of a
second straight line M1 radially extending from the rotation axis RS and the
indentation 30 and an angle of rotation of the second straight line M1 in a plan view
as seen from an angle parallel with the axial direction of the rotation axis RS.
Moreover, a point of intersection of the second straight line M1 and the indentation 30
10 in a part of the indentation 30 that is furthest forward in the direction of rotation DR is
defined as an apex 33 of the indentation 30. In a case in which the amount by which
the indentation 30 indents in the direction of rotation DR is expressed as "depth", the
apex 33 is closest to the leading edge 21 from among the points constituting the
indentation 30, and constitutes a deep part of the indentation 30. The apex 33 is
15 between the intersection portion 31 of the trailing edge 22 and the trailing edge end
portion 32. That is, the indentation 30 is formed such that the intersection portion
31, the apex 33, and the trailing edge end portion 32 are arranged in this order from
the inner periphery toward the outer periphery of the trailing edge 22. The
indentation 30 is open in a direction opposite to the direction of rotation DR, and a
20 part of the indentation 30 that is close to the apex 33 is narrower than a part of the
indentation 30 that is between the intersection portion 31 and the trailing edge end
portion 32.
[0026]
Fig. 3 is a side view conceptually showing an example of a distribution of blade
25 thickness of the trailing edge 22 shown in Fig. 2. Fig. 4 is a diagram showing a
blade surface distribution of the trailing edge 22 of the axial flow fan 100 according to
Embodiment 1. Fig. 3 is a conceptual diagram showing the blade thickness of the
blade 20 and the blade thickness of the trailing edge 22 as seen from an angle
indicated by an arrow SW in Fig. 2. In Fig. 3, a pressure surface 25a indicates a
30 portion of the pressure surface 25 of the blade 20 that is further forward in the
12
direction of rotation DR than the trailing edge 22, and a pressure surface 25e
represents the pressure surface 25 of the trailing edge 22. Further, in Fig. 3, a
suction surface 26a indicates a portion of the suction surface 26 of the blade 20 that
is further forward in the direction of rotation DR than the trailing edge 22, and a
5 suction surface 26e represents the suction surface 26 of the trailing edge 22. Fig. 4
plots radial distance in abscissa and axial distance in ordinate, and conceptually
represents an axial change in blade surface of the trailing edge in a radial direction.
The blade surface shown in Fig. 4 is the pressure surface 25 or the suction surface
26. Next, the blade thickness of the trailing edge 22 is described with reference to
10 Figs. 3 and 4.
[0027]
The blade thickness of the blade 20 is defined as a distance between a part of
the pressure surface 25 and a part of the suction surface 26 that are at the same
radial distance from the rotation axis RS. Moreover, the blade thickness of the
15 trailing edge 22 is defined as a distance between a part of the pressure surface 25 of
the trailing edge 22 and a part of the suction surface 26 of the trailing edge 22 that
are at the same radial distance from the rotation axis RS. For example, as shown in
Fig. 3, the blade thickness of the blade 20 at the intersection portion 31 is a blade
thickness T1. Further, the blade thickness of the blade 20 at the apex 33 is a blade
20 thickness T3. Furthermore, the blade thickness of the blade 20 at the trailing edge
end portion 32 is a blade thickness T2. The blade thickness of the blade 20 may be
defined as a distance in the axial direction of the rotation axis RS between a part of
the pressure surface 25 of the trailing edge 22 and a part of the suction surface 26 of
the trailing edge 22 that are at the same radial distance from the rotation axis RS.
25 Moreover, the blade thickness of the trailing edge 22 may be defined as a distance in
the axial direction of the rotation axis RS between a part of the pressure surface 25 of
the trailing edge 22 and a part of the suction surface 26 of the trailing edge 22 that
are at the same radial distance from the rotation axis RS.
[0028]
30 Fig. 5 is another plan view of a blade 20 shown in Fig. 1 as seen from an angle
13
parallel with the axial direction of the rotation axis RS. Fig. 6 is a diagram
conceptually showing a shape of a cross-section of the trailing edge 22 of the blade
20 shown in Fig. 5 as taken along line M-M. Fig. 7 is a diagram conceptually
showing a shape of another cross-section of the trailing edge 22 of the blade 20
5 shown in Fig. 5 as taken along line M-M. Fig. 8 is a diagram conceptually showing a
shape of another cross-section of the trailing edge 22 of the blade 20 shown in Fig. 5
as taken along line M-M. As shown in Fig. 6, in a case in which the trailing edge 22
is rectangular, the blade thickness is defined as that of a portion of the trailing edge
22 at the blade tip. Further, as shown in Fig. 7, in a case in which the trailing edge
10 22 has a round shape, the blade thickness is defined as that of a portion of the trailing
edge 22 at a starting point of the round shape. Further, as shown in Fig. 8, in a case
in which the trailing edge 22 has a pointed end, the blade thickness is defined as that
of a portion of the trailing edge 22 at a starting point of the pointed end. The blade
thickness of the trailing edge 22 shown in Figs. 6 to 8 is shown as the blade thickness
15 T in Figs. 6 to 8.
[0029]
As shown in Figs. 3 and 4, the indentation 30 of the trailing edge 22 increases
in blade thickness outward from the intersection point 31 and reaches a maximum
blade thickness inside of the apex 33. The blade 20 has, at the indentation 30, a
20 maximum thickness portion 36 at which a thickness of the blade 20 is maximum, and
which is positioned radially inside of the apex 33. Thus, the indentation 30 of the
blade 20 has the maximum thickness portion 36 in an area between the apex 33 and
the intersection portion 31. The area between the apex 33 and the intersection
portion 31 is referred to as "inner peripheral area 38". Accordingly, the indentation
25 30 of the blade 20 has the maximum thickness portion 36 in the inner peripheral area
38. As shown in Fig. 3, the blade thickness TL of the maximum thickness portion 36
is greatest of the thicknesses at the indentation 30. The blade thickness of the
indentation 30 of the trailing edge 22 is partially greater radially inside of the apex 33
than the blade thickness of the apex 33, which is the deepest part of the indentation
30 30 in the direction of rotation DR. Accordingly, at the indentation 30 of the trailing
14
edge 22, the blade thickness T1 of the intersection portion 31, which is the inner
peripheral end portion of the indentation 30, and the blade thickness T3 of the apex
33 are smaller than the blade thickness TL of the maximum thickness portion 36.
[0030]
5 Fig. 3 shows an example of the trailing edge 22. Accordingly, the
configuration of the blade thickness of the indentation 30 at the trailing edge 22 needs
only be formed as indicated below, and the configuration of the pressure surface 25
and the configuration of the suction surface 26 do not need to be identical.
Therefore, for example, either the pressure surface 25 or the suction surface 26 may
10 be constituted by a curved surface, and the other blade surface may be constituted by
a flat surface. Alternatively, the pressure surface 25 and the suction surface 26 may
be constituted by different curved surfaces.
[0031]
It is desirable that as shown in Fig. 3, the maximum thickness portion 36 be
15 between the intersection portion 31, which is the inner peripheral end portion of the
indentation 30, and the apex 33 and be closer to the apex 33 than a center 37
between the intersection portion 31, which is the inner peripheral end portion of the
indentation 30, and the apex 33.
[0032]
20 [Operation of Axial Flow Fan 100]
When the axial flow fan 100 rotates in the direction of rotation DR shown in Fig.
1, each blade 20 presses ambient air with the pressure surface 25 to generate an
airflow in the direction F shown in Fig. 1. Further, the rotation of the axial flow fan
100 produces a pressure difference between the pressure surface 25 and the suction
25 surface 26 in an area around each blade 20. Specifically, the suction surface 26 is
subjected to a lower pressure than the pressure surface 25.
[0033]
[Effects of Axial Flow Fan 100]
Fig. 9 is a plan view of an axial flow fan 100L according to a comparative
30 example as seen from an angle parallel with an axial direction of a rotation axis RS.
15
Fig. 10 is a side view conceptually showing a distribution of blade thickness of a
trailing edge 22 of a blade 20L shown in Fig. 9. Fig. 11 is a diagram showing a blade
surface distribution of the trailing edge 22 of the axial flow fan 100L according to the
comparative example. In general, an axial flow fan is configured such that an air
5 flow having flowed in through the leading edge of a blade is caused by a centrifugal
force to flow radially outward. In the axial flow fan 100L according to the
comparative example, an airflow flowing radially inward from the apex 33 passes
through the indentation 30 in the process of moving radially outward in the axial flow
fan 100L. Therefore, in the axial flow fan 100L, airflows flowing in radially inside of
10 the apex 33 concentrate near the apex 33, so that a wind velocity is high near the
apex 33.
[0034]
As shown in Figs. 10 and 11, the axial flow fan 100L according to the
comparative example is configured such that the maximum thickness portion 36 is
15 positioned at the apex 33. The axial flow fan 100L according to the comparative
example is configured such that the blade thickness TE of the maximum thickness
portion 36, which is positioned at the apex 33, is greatest of the blade thicknesses at
the indentation 30. That is, as shown in Figs. 10 and 11, the axial flow fan 100L
according to the comparative example is configured such that the apex 33, which is
20 close to the middle of the length of the blade as seen on identical radii, is greatest in
blade thickness. In general, at a place at which a blade tip is thick, separation of an
airflow from the blade produces a slipstream with a great difference in velocity
between the pressure surface and the suction surface, so that a blade tip vortex is
generated. In the axial flow fan 100L, in which the apex 33, at which a wind velocity
25 is high, is greatest in blade thickness, separation of an airflow from the blade
produces a slipstream with a great difference in velocity between the pressure surface
and the suction surface, so that a blade tip vortex is easily generated. Meanwhile,
the indentation needs a portion with an increased thickness for the securing of
strength against a centrifugal force that is applied to the blade.
30 [0035]
16
Fig. 12 is a schematic view showing a relationship between the blade 20 of the
axial flow fan 100 according to Embodiment 1 and airflows. The relationship
between the blade 20 of the axial flow fan 100 according to Embodiment 1 and
airflows is described with reference to Fig. 12. As compared with the axial flow fan
5 100L according to the comparative example, the axial flow fan 100 according to
Embodiment 1 is configured such that the blade 20 has, at the indentation 30, a
maximum thickness portion 36 at which a thickness of the blade 20 is maximum, and
which is positioned radially inside of the apex 33. Since the axial flow fan 100 is
configured such that a thickness of a portion of the blade that is positioned inside of
10 the apex 33 is a maximum thickness, the axial flow fan 100 can make the difference
in velocity between the pressure surface and the suction surface of a slipstream
produced at the apex 33, at which a wind velocity is high, smaller than the axial flow
fan 100L, and can inhibit blade tip vortices WV.
[0036]
15 The inner peripheral area 38 in which the maximum thickness portion 36 is
provided, and which is positioned inside (Y2 side) of the apex 33, produces a
comparatively weak slipstream and hardly forms blade tip vortices WV, as an air flow
FL2 reaching the blade tip is small in amount and low in velocity. Note, however,
that the inner peripheral area 38 can secure strength against a centrifugal force by
20 having the maximum thickness portion 36. That is, the inner peripheral area 38
prioritizes the strength of the blade 20 over the inhibition of blade tip vortices WV.
[0037]
In an outer peripheral area 39 positioned outside (Y1 side) of the apex 33, an
airflow reaching the blade tip of the trailing edge 22 is large in amount and high in
25 velocity, as an airflow FL1 having flowed in through the leading edge 21 of the blade
20 is caused by a centrifugal force to flow radially outward. The outer peripheral
area 39 is an area between the apex 33 and the trailing edge end portion 32, which is
the outer peripheral end portion of the indentation 30. However, in the outer
peripheral area 39, which is thinner in blade thickness than the inner peripheral area
30 38 and shorter in distance between the pressure surface 25 and the suction surface
17
26 than the inner peripheral area 38, blade tip vortices WV formed downstream of the
blade tip, if any, are small and weak. That is, by prioritizing the flow of gas over the
strength of the blade 20, the outer peripheral area 39 prioritizes the inhibition of blade
tip vortices WV that are formed downstream of the blade tip.
5 [0038]
In response to an airflow FL, the axial flow fan 100 can secure the strength of
the indentation 30 in the inner peripheral area 38, through which a small amount of
airflow passes, and, at the same time, can inhibit the generation of blade tip vortices
WV, which are a cause of an energy loss, downstream of the blade tip of the trailing
10 edge 22 in the outer peripheral area 39, through which a large amount of airflow
passes. As a result, the axial flow fan 100 can achieve an energy-saving and lownoise air-sending device. In general, since the volume of air that passes is large on
the outer periphery of a blade, the length of the blade tends to be great on the outer
periphery. In the axial flow fan 100 according to Embodiment 1, the volume of the
15 blade 20 is reduced by reducing the thickness of a portion of the blade 20 that is
positioned outside of the apex 33. This makes it possible to reduce the weights of
the blade 20 and the axial flow fan 100.
[0039]
Further, the axial flow fan 100 is configured such that the maximum thickness
20 portion 36 is between the intersection portion 31, which is the inner peripheral end
portion of the indentation 30, and the apex 33 and is closer to the apex 33 than a
center 37 between the intersection portion 31, which is the inner peripheral end
portion of the indentation 30, and the apex 33. Since the apex 33 is subjected to a
high load by a centrifugal force, the strength of the blade 20 can be secured by
25 positioning the maximum thickness portion 36 closer to the apex 33 than the center
37.
[0040]
Embodiment 2.
Fig. 13 is a plan view of an axial flow fan 100A according to Embodiment 2 as
30 seen from an angle parallel with an axial direction of a rotation axis RS. Fig. 14 is a
18
side view conceptually showing an example of a distribution of blade thickness of a
trailing edge 22 of a blade 20A shown in Fig. 13. Fig. 15 is a diagram showing a
blade surface distribution of the trailing edge 22 of the axial flow fan 100A according
to Embodiment 2. Fig. 14 shows an example of the trailing edge 22, and as
5 indicated by the blade surface of Fig. 15, the blade thickness of the blade 20A may be
specified by either the pressure surface 25 or the suction surface 26. The axial flow
fan 100A according to Embodiment 2 is intended to specify the configuration of a
portion between the apex 33 and the trailing edge end portion 32, which is the outer
peripheral end portion of the indentation 30. Components identical to those of the
10 axial flow fan 100 or other axial flow fans of Figs. 1 to 12 are given identical reference
signs, and a description of such components is omitted.
[0041]
The axial flow fan 100A according to Embodiment 2 is configured such that the
blade 20A has, at the indentation 30, a minimum thickness portion 34 at which a
15 thickness of the blade 20A is minimum, and which is positioned radially outside of the
apex 33. The axial flow fan 100A according to Embodiment 2 is configured such that
the blade 20A has, at the indentation 30, a minimum thickness portion 34 at which a
thickness of the blade 20A is minimum, and which is positioned between the apex 33
and the trailing edge end portion 32, which is the outer peripheral end portion of the
20 indentation 30. That is, the axial flow fan 100A according to Embodiment 2 has the
minimum thickness portion 34 in the outer peripheral area 39. As shown in Fig. 14,
the blade thickness TS of the maximum thickness portion 34 is smallest of the
thicknesses at the indentation 30. That is, the indentation 30 of the trailing edge 22
decreases in blade thickness outward from the apex 33 and is smallest in blade
25 thickness inside of the trailing edge end portion 32, which is the outer peripheral end
portion of the indentation 30. The blade thickness of the indentation 30 of the trailing
edge 22 is partially smaller radially outside of the apex 33 than the blade thickness of
the apex 33, which is the deepest part of the indentation 30 in the direction of rotation
DR. Accordingly, at the indentation 30 of the trailing edge 22, the blade thickness T2
30 of the trailing edge end portion 32, which is the outer peripheral end portion of the
19
indentation 30, and the blade thickness T3 of the apex 33 are greater than the blade
thickness TS of the minimum thickness portion 34.
[0042]
As shown in Figs. 14 and 15, the indentation 30 of the trailing edge 22
5 increases in blade thickness outward from the intersection point 31 and reaches a
maximum blade thickness inside of the apex 33. Moreover, the indentation 30 of the
trailing edge decreases in thickness of the blade outward from the maximum
thickness portion 36, at which the thickness of the blade 20A is maximum, and is
smallest in blade thickness at the minimum thickness portion 34, which is positioned
10 between the apex 33 and the trailing edge end portion 32. Moreover, the indentation
30 of the trailing edge increases in blade thickness from the minimum thickness
portion 34 toward the trailing edge end portion 32.
[0043]
[Effects of Axial Flow Fan 100A]
15 The axial flow fan 100A according to Embodiment 2 is configured such that the
blade 20A has, at the indentation 30, a minimum thickness portion 34 at which a
thickness of the blade 20A is minimum, and which is positioned radially outside of the
apex 33. The axial flow fan 100A according to Embodiment 2 is configured such that
the blade 20A has, at the indentation 30, a minimum thickness portion 34 at which a
20 thickness of the blade 20A is minimum, and which is positioned between the apex 33
and the trailing edge end portion 32, which is the outer peripheral end portion of the
indentation 30. An airflow flowing along a blade surface is subjected to a centrifugal
force to flow radially outward from the apex 33 of the indentation 30. In the axial flow
fan 100A, a thickness of a portion of the blade that is positioned radially outside is
25 reduced at the indentation 30, at which airflows concentrate. This makes it hard for
an airflow separated from the blade tips of the pressure surface and the suction
surface to be sucked in behind the blade tips, and makes it possible to reduce blade
tip vortices WV that are generated downstream of the blade tips. As a result, the
axial flow fan 100A reduces an energy loss attributed to the blade tip vortices WV and
30 reduces disturbances of air flow, thereby making it possible to achieve energy
20
conservation and reduce noise. Further, in the axial flow fan 100A, in which a
thickness of a portion of the blade that is positioned radially outside is reduced, a
reduced force is applied to the indentation 30 by a centrifugal force. This makes it
possible to secure the strength of the axial flow fan 100A.
5 [0044]
Embodiment 3.
Fig. 16 is a plan view of an axial flow fan 100B according to Embodiment 3 as
seen from an angle parallel with an axial direction of a rotation axis RS. Fig. 17 is a
side view conceptually showing an example of a distribution of blade thickness of a
10 trailing edge 22 of a blade 20B shown in Fig. 16. Fig. 18 is a diagram showing a
blade surface distribution of the trailing edge 22 of the axial flow fan 100B according
to Embodiment 3. Fig. 16 shows an example of the trailing edge 22, and as
indicated by the blade surface of Fig. 18, the blade thickness of the blade 20B may be
specified by either the pressure surface 25 or the suction surface 26. The axial flow
15 fan 100B according to Embodiment 3 is intended to specify the configuration of a
portion between the apex 33 and the trailing edge end portion 32, which is the outer
peripheral end portion of the indentation 30. Components identical to those of the
axial flow fan 100 or other axial flow fans of Figs. 1 to 15 are given identical reference
signs, and a description of such components is omitted.
20 [0045]
The axial flow fan 100B according to Embodiment 3 is configured such that the
blade 20B has, at the indentation 30, a minimum thickness portion 34 at which a
thickness of the blade 20B is minimum, and which is positioned radially outside of the
apex 33. The axial flow fan 100B according to Embodiment 3 is configured such that
25 the blade 20B has, at the indentation 30, a minimum thickness portion 34 at which a
thickness of the blade 20B is minimum, and which is positioned at the trailing edge
end portion 32, which is the outer peripheral end portion of the indentation 30. That
is, the indentation 30 of the trailing edge 22 decreases in blade thickness outward
from the apex 33 and is smallest in blade thickness at the trailing edge end portion
30 32, which is the outer peripheral end portion of the indentation 30. The blade
21
thickness of the indentation 30 of the trailing edge 22 is partially smaller radially
outside of the apex 33 than the blade thickness of the apex 33, which is the deepest
part of the indentation 30 in the direction of rotation DR. Accordingly, at the
indentation 30 of the trailing edge 22, the blade thickness T3 of the apex 33 is greater
5 than the blade thickness TS of the minimum thickness portion 34.
[0046]
As shown in Figs. 14 and 15, the indentation 30 of the trailing edge 22
increases in blade thickness outward from the intersection point 31 and reaches a
maximum blade thickness inside of the apex 33. Moreover, the indentation 30 of the
10 trailing edge decreases in blade thickness outward from the maximum thickness
portion 36, at which the thickness of the blade 20B is maximum, toward the apex 33
and then toward the trailing edge end portion 32.
[0047]
[Effects of Axial Flow Fan 100B]
15 The axial flow fan 100B according to Embodiment 3 is configured such that the
blade 20B has, at the indentation 30, a minimum thickness portion 34 at which a
thickness of the blade 20B is minimum, and which is positioned radially outside of the
apex 33. The axial flow fan 100A according to Embodiment 2 is configured such that
the blade 20B has, at the indentation 30, a minimum thickness portion 34 at which a
20 thickness of the blade 20B is minimum, and which is positioned between the apex 33
and the trailing edge end portion 32, which is the outer peripheral end portion of the
indentation 30. An airflow flowing along a blade surface is subjected to a centrifugal
force to flow radially outward from the apex 33 of the indentation 30. In the axial flow
fan 100B, a thickness of a portion of the blade that is positioned radially outside is
25 reduced at the indentation 30, at which airflows concentrate. This makes it possible
to reduce blade tip vortices WV that are generated downstream of the blade tips and,
by reducing an energy loss and reducing disturbances of airflow, achieve energy
conservation and reduced noise. Further, in the axial flow fan 100B, in which a
thickness of a portion of the blade that is positioned radially outside is reduced, a
30 reduced force is applied to the indentation 30 by a centrifugal force. This makes it
22
possible to secure the strength of the axial flow fan 100B. Further, since the axial
flow fan 100B is configured such that the thickness of the blade 20 gradually changes
from the inner periphery toward the outer periphery of the blade 20, a local stress
concentration hardly occurs. This makes it possible to better secure the strength of
5 the axial flow fan 100B than that of the axial flow fan 100A.
[0048]
Embodiment 4.
Fig. 19 is a plan view of an axial flow fan 100C according to Embodiment 4 as
seen from an angle parallel with an axial direction of a rotation axis RS. Fig. 20 is a
10 side view conceptually showing an example of a distribution of blade thickness of a
trailing edge 22 of a blade 20C shown in Fig. 19. Fig. 21 is a diagram showing a
blade surface distribution of the trailing edge 22 of the axial flow fan 100C according
to Embodiment 4. Fig. 19 shows an example of the trailing edge 22, and as
indicated by the blade surface of Fig. 21, the blade thickness of the blade 20C may
15 be specified by either the pressure surface 25 or the suction surface 26. The axial
flow fan 100C according to Embodiment 4 is intended to specify the configuration of a
portion between the apex 33 and the intersection portion 31, which is the inner
peripheral end portion of the indentation 30. Components identical to those of the
axial flow fan 100 or other axial flow fans of Figs. 1 to 18 are given identical reference
20 signs, and a description of such components is omitted.
[0049]
The axial flow fan 100C according to Embodiment 4 is configured such that the
blade 20C has, at the indentation 30, a maximum thickness portion 36 at which a
thickness of the blade 20C is maximum, and which is positioned radially inside of the
25 apex 33. The axial flow fan 100C according to Embodiment 4 is configured such
that the blade 20C has, at the indentation 30, a maximum thickness portion 36 at
which a thickness of the blade 20C is maximum, and which is positioned at the
intersection portion 31, which is the inner peripheral end portion of the indentation 30.
That is, the indentation 30 of the trailing edge 22 increases in blade thickness inward
30 from the apex 33 and reaches a maximum blade thickness at the intersection portion
23
31, which is the inner peripheral end portion of the indentation 30. The blade
thickness of the indentation 30 of the trailing edge 22 is partially greater radially inside
of the apex 33 than the blade thickness of the apex 33, which is the deepest part of
the indentation 30 in the direction of rotation DR. Accordingly, at the indentation 30
5 of the trailing edge 22, the blade thickness T3 of the apex 33 is smaller than the blade
thickness TL of the maximum thickness portion 36.
[0050]
As shown in Figs. 20 and 21, the indentation 30 of the trailing edge 22
decreases in blade thickness outward from the intersection portion 31 having the
10 maximum thickness portion 36, at which the thickness of the blade 20B is maximum,
toward the apex 33 and then toward the trailing edge end portion 32.
[0051]
[Effects of Axial Flow Fan 100C]
The axial flow fan 100C according to Embodiment 4 is configured such that the
15 blade 20C has, at the indentation 30, a maximum thickness portion 36 at which a
thickness of the blade 20C is maximum, and which is positioned at the intersection
portion 31, which is the inner peripheral end portion of the indentation 30. The
indentation 30 of the axial flow fan 100C according to Embodiment 4 decreases in
blade thickness and mass toward the outer periphery, to which a centrifugal force is
20 applied. This makes it possible to secure the strength of the blade 20. Further, the
indentation 30 of the axial flow fan 100C according to Embodiment 4 has no abrupt
change in blade thickness of the trailing edge 22 in a radial direction. The axial flow
fan 100 according to Embodiment 4 reduces changes in strength of vortices that are
generated inside and outside of the intersection portion 31, which is the inner
25 peripheral end portion of the indentation 30, and reduces disturbances of airflow.
[0052]
Embodiment 5.
Fig. 22 is a plan view of an axial flow fan 100D according to Embodiment 5 as
seen from an angle parallel with an axial direction of a rotation axis RS. Fig. 23 is an
30 enlarged view conceptually showing blade tip indentations 40 shown in Fig. 22.
24
Components identical to those of the axial flow fan 100 or other axial flow fans of
Figs. 1 to 21 are given identical reference signs, and a description of such
components is omitted.
[0053]
5 A blade 20D has, as a portion of the trailing edge 22 that is close to the outer
periphery, a blade tip indentation 40 having a serrated shape. The blade tip
indentation 40 is a second indentation of the blade 20D, and is a portion of at least
the indentation 30. More specifically, the blade tip indentation 40, which is the
second indentation, is positioned between the apex 33 and the trailing edge end
10 portion 32, which is the outer peripheral end portion of the indentation 30. That is,
the blade tip indentation 40, which is the second indentation, is positioned at least in
the outer peripheral area 39 of the indentation 30. The blade tip indentation 40,
which is the second indentation, needs only be positioned at least in the outer
peripheral area 39 of the indentation 30, and may be a portion of the trailing edge 22
15 that is positioned outside of the trailing edge end portion 32. Accordingly, the
indentation 30 has a blade tip indentation 40 having a serrated shape along the
trailing edge as a portion of the indentation 30 that is positioned outside of the apex
33.
[0054]
20 The blade tip indentation 40, which is the second indentation, includes a
plurality of notches 41 and mountain portions 42 each positioned between one and
another of the plurality of notches 41 and projecting in the direction of rotation DR,
and is a series of the notches 41 and the mountain portions 42 along the trailing edge
22. In the example shown in Fig. 22, there are provided three notches 41 and two
25 mountain portions 42. As a result, the portion of the trailing edge 22 that is close to
the outer periphery has a serrated shape. Assume that, as shown in Fig. 23, a
distance between a position 44a of an apex 44 and a position 45a of a valley portion
45 in the direction of rotation DR is a notch depth TD. The apex 44 is a top of a
mountain portion 42 in the direction in which the mountain portion 42 projects, and the
30 valley portion 45 is the position of a valley floor between one mountain portion 42 and
25
another mountain portion 42. That is, the depth TD is the depth of a notch of the
blade tip indentation 40, and is the difference in height between a mountain and a
valley of the blade tip indentation 40.
[0055]
5 The blade tip indentation 40 needs only include a plurality of notches 41 and
may include any number of notches 41. Although, in the example shown in Figs. 22
and 23, the notches 41 each has a triangular shape in a plan view of the axial flow fan
100D as seen from an angle parallel with the axial direction of the rotation axis RS,
the shape of each of the notches 41 is not limited to such a shape. Some or all of
10 the notches 41 of the blade tip indentation 40 may have different shapes.
[0056]
Although, in the example shown in Figs. 22 and 23, the mountain portions 42
each has a triangular shape in a plan view of the axial flow fan 100D as seen from an
angle parallel with the axial direction of the rotation axis RS, the shape of each of the
15 mountain portions 42 is not limited to such a shape. Some or all of the mountain
portions 42 of the blade tip indentation 40 may have different shapes.
[0057]
[Effects of Axial Flow Fan 100D]
The indentation 30 has a blade tip indentation 40 having a serrated shape
20 along the trailing edge as a portion of the indentation 30 that is positioned outside of
the apex 33. Since the portion of the indentation 30 that is close to the outer
periphery is smaller in blade thickness than the apex 33, blade tip vortices WV that
are generated at an end portion of the blade 20D by an airflow FL are small. By
including the serrated blade tip indentation 40 on the outer periphery, at which a wind
25 velocity is high, the axial flow fan 100D can create small disturbances in advance,
further weaken the blade tip vortices WV, and thereby reduce trailing vortices.
[0058]
Embodiment 6.
Fig. 24 is a plan view of an axial flow fan 100E according to Embodiment 6 as
30 seen from an angle parallel with an axial direction of a rotation axis RS.
26
Components identical to those of the axial flow fan 100 or other axial flow fans of
Figs. 1 to 23 are given identical reference signs, and a description of such
components is omitted.
[0059]
5 A blade 20E has, as a portion of the trailing edge 22 that is close to the inner
periphery, a blade tip indentation 40 having a serrated shape. The blade tip
indentation 40 is a second indentation of the blade 20E, and is a portion of at least
the indentation 30. More specifically, the blade tip indentation 40, which is the
second indentation, is positioned between the apex 33 and the intersection portion
10 31, which is the inner peripheral end portion of the indentation 30. That is, the blade
tip indentation 40, which is the second indentation, is positioned at least in the inner
peripheral area 38 of the indentation 30. The blade tip indentation 40, which is the
second indentation, needs only be positioned at least in the inner peripheral area 38
of the indentation 30, and may be a portion of the trailing edge 22 that is positioned
15 inside of the intersection portion 31. Accordingly, the indentation 30 has a blade tip
indentation 40 having a serrated shape along the trailing edge as a portion of the
indentation 30 that is positioned inside of the apex 33.
[0060]
[Effects of Axial Flow Fan 100E]
20 The indentation 30 has a blade tip indentation 40 having a serrated shape
along the trailing edge as a portion of the indentation 30 that is positioned inside of
the apex 33. By including the serrated blade tip indentation 40 on the inner
periphery, at which a thickness of the blade 20 is great, the axial flow fan 100E can
create small disturbances in advance also in a portion in which the strength of the
25 blade 20 is secured, further weaken the blade tip vortices WV, and thereby reduce
trailing vortices.
[0061]
Embodiment 7.
Fig. 25 is a plan view of an axial flow fan 100F according to Embodiment 7 as
30 seen from an angle parallel with an axial direction of a rotation axis RS.
27
Components identical to those of the axial flow fan 100 or other axial flow fans of
Figs. 1 to 24 are given identical reference signs, and a description of such
components is omitted.
[0062]
5 The blade 20F has, as portions of the trailing edge 22 that are close to the
outer periphery and the inner periphery, blade tip indentations 40 each having a
serrated shape. The blade tip indentations 40 are second indentations of the blade
20F, and are portions of at least the indentation 30. More specifically, one of the
blade tip indentations 40, which are the second indentations, is positioned between
10 the apex 33 and the intersection portion 31, which is the inner peripheral end portion
of the indentation 30, and the other of the blade tip indentations 40, which are the
second indentations, is positioned between the apex 33 and the trailing edge end
portion 32, which is the outer peripheral end portion of the indentation 30. That is,
one of the blade tip indentations 40, which are the second indentations, is positioned
15 in the inner peripheral area 38 of the indentation 30, and the other of the blade tip
indentations 40, which are the second indentations, is positioned in the outer
peripheral area 39 of the indentation 30.
[0063]
One of the blade tip indentations 40, which are the second indentations, needs
20 only be positioned at least in the inner peripheral area 38 of the indentation 30, and
may be a portion of the trailing edge 22 that is positioned inside of the intersection
portion 31. Further, the other of the blade tip indentations 40, which are the second
indentations, needs only be positioned at least in the outer peripheral area 39 of the
indentation 30, and may be a portion of the trailing edge 22 that is positioned outside
25 of the trailing edge end portion 32. Accordingly, the indentation 30 has blade tip
indentations 40 having serrated shapes along the trailing edge as portions of the
indentation 30 that are positioned inside and outside of the apex 33.
[0064]
It is desirable that the axial flow fan 100F be configured such that a depth TD1
30 of any one of the notches of the blade tip indentation 40 positioned inside of the apex
28
33 is greater than a depth TD2 of a notch of the blade tip indentation 40 positioned
outside of the apex 33. Further, it is further desirable that a minimum value of the
depth TD1 of each of the plurality of notches of the blade tip indentation 40 positioned
inside of the apex 33 be greater than a maximum value of the depth TD2 of each of
5 the plurality of notches of the blade tip indentation 40 positioned outside of the apex
33. The depth TD1 and the depth TD2 are defined by the depth TD described
above.
[0065]
It is desirable that the axial flow fan 100F be configured such that in the inner
10 peripheral area 38, a depth TD1 of any one of notches of the blade tip indentation 40
positioned inside of the maximum thickness portion 36 is greater than a depth TD3 of
a notch of the blade tip indentation 40 positioned outside of the maximum thickness
portion 36. This configuration may be applied to the axial flow fan 100E described
above. The depth TD3 is defined by the depth TD described above.
15 [0066]
[Effects of Axial Flow Fan 100F]
The indentation 30 has a blade tip indentation 40 having a serrated shape
along the trailing edge as a portion of the indentation 30 that is positioned outside of
the apex 33. Since the portion of the indentation 30 that is close to the outer
20 periphery is smaller in blade thickness than the apex 33, blade tip vortices WV that
are generated at an end portion of the blade 20D by an airflow FL are small. By
including the serrated blade tip indentation 40 on the outer periphery, at which a wind
velocity is high, the axial flow fan 100F can create small disturbances in advance,
further weaken the blade tip vortices WV, and thereby reduce trailing vortices.
25 Furthermore, the indentation 30 has a blade tip indentation 40 having a serrated
shape along the trailing edge as a portion of the indentation 30 that is positioned
inside of the apex 33. By including the serrated blade tip indentation 40 on the inner
periphery, at which a thickness of the blade 20 is great, the axial flow fan 100F can
create small disturbances in advance also in a portion in which the strength of the
30 blade 20 is secured, further weaken the blade tip vortices WV, and thereby reduce
29
trailing vortices.
[0067]
The indentation 30 is configured such that in a direction of rotation DR of the
blade 20, a depth TD1 of any one of notches of the blade tip indentation 40 positioned
5 inside of the apex 33 is greater than a depth TD2 of a notch of the blade tip
indentation 40 positioned outside of the apex 33. By having a blade tip indentation
40 positioned on the inner periphery, at which a thickness of the blade 20 is great and
a slipstream is easily generated, and formed by notches that are deeper than those of
a blade tip portion 40 positioned on the outer periphery, the axial flow fan 100F can
10 create small disturbances in advance, further weaken the blade tip vortices WV, and
thereby reduce trailing vortices. Since the thickness of a portion of the blade 20 that
is positioned on the inner periphery is greater than the thickness of a portion of the
blade 20 that is positioned on the outer periphery, the axial flow fan 100F can better
secure the strength of the portion of the blade 20 that is positioned on the inner
15 periphery than the strength of the portion of the blade 20 that is positioned on the
outer periphery. Therefore, in the axial flow fan 100F, the depth of a notch of the
blade tip indentation 40 positioned on the inner periphery of the blade 20 can be
made greater than the depth of a notch of the blade tip indentation 40 positioned on
the outer periphery of the blade 20.
20 [0068]
The indentation 30 is configured such that in a direction of rotation DR of the
blade 20, a depth TD1 of any one of notches of the blade tip indentation 40 positioned
inside of the maximum thickness portion 36 is greater than a depth TD3 of a notch of
the blade tip indentation 40 positioned outside of the maximum thickness portion 36.
25 By having a blade tip indentation 40 positioned on the inner periphery, at which a
thickness of the blade 20 is great and a slipstream is easily generated, and formed by
notches that are deeper than those of a blade tip portion 40 positioned on the outer
periphery, the axial flow fan 100F can create small disturbances in advance, further
weaken the blade tip vortices WV, and thereby reduce trailing vortices. Since the
30 thickness of a portion of the blade 20 that is positioned on the inner periphery is
30
greater than the thickness of a portion of the blade 20 that is positioned on the outer
periphery, the axial flow fan 100F can better secure the strength of the portion of the
blade 20 that is positioned on the inner periphery than the strength of the portion of
the blade 20 that is positioned on the outer periphery. Therefore, in the axial flow fan
5 100F, the depth of a notch of the blade tip indentation 40 positioned on the inner
periphery of the blade 20 can be made greater than the depth of a notch of the blade
tip indentation 40 positioned on the outer periphery of the blade 20.
[0069]
Embodiment 8.
10 Embodiment 8 illustrates a case in which the axial flow fan 100 or other axial
flow fans of Embodiments 1 to 7 are applied to an outdoor unit 50 serving as an airsending device in a refrigeration cycle apparatus 70.
[0070]
Fig. 26 is a schematic view of the refrigeration cycle apparatus 70 according to
15 Embodiment 8. While the following describes a case in which the refrigeration cycle
apparatus 70 is used in air conditioning, the refrigeration cycle apparatus 70 is not
limited to use in air conditioning. The refrigeration cycle apparatus 70 is used for
example in a refrigerator, a freezer, a self-vending machine, an air-conditioning
apparatus, a refrigerating apparatus, or a water heater for a freezing or air20 conditioning purpose.
[0071]
As shown in Fig. 26, the refrigeration cycle apparatus 70 includes a refrigerant
circuit 71 connecting a compressor 64, a condenser 72, an expansion valve 74, and
an evaporator 73 in sequence by refrigerant pipes. The condenser 72 is provided
25 with a condenser fan 72a configured to send air to the condenser 72 for use in heat
exchange. Further, the evaporator 73 is provided with an evaporator fan 73a
configured to send air to the evaporator 73 for use in heat exchange. At least either
the condenser fan 72a or the evaporator fan 73a is constituted by the axial flow fan
100 or other axial flow fans of Embodiments 1 to 7. By providing the refrigerant
30 circuit 71 with a flow switch device, such as a four-way valve, configured to switch the
31
flow of refrigerant, the refrigeration cycle apparatus 70 may be configured to switch
between heating operation and cooling operation.
[0072]
Fig. 27 is a perspective view of the outdoor unit 50, which is an air-sending
5 device, as seen from an air outlet side. Fig. 28 is a diagram for explaining a
configuration of the outdoor unit 50 from the top. Fig. 29 is a diagram showing a
state in which a fan grille has been removed from the outdoor unit 50. Fig. 30 is a
diagram showing an internal configuration of the outdoor unit 50 with the fan grille, a
front panel, or other components removed from the outdoor unit 50.
10 [0073]
As shown in Figs. 27 to 30, an outdoor unit body 51 serving as a casing is
configured as a housing having a pair of left and right side surfaces 51a and 51c, a
front surface 51b, a back surface 51d, a top surface 51e, and a bottom surface 51f.
The side surface 51a and the back surface 51d are provided with openings through
15 which air is suctioned from outside. Further, in the front surface 51b, a front panel
52 is provided with an air outlet 53 serving as an opening through which air is blown
out. Furthermore, the air outlet 53 is covered with a fan grille 54, whereby safety
measures are taken by preventing contact between an object outside the outdoor unit
body 51 and the axial flow fan 100. The arrow AR of Fig. 28 indicates the flow of air.
20 [0074]
The outdoor unit body 51 houses the axial flow fan 100 and a fan motor 61.
The axial flow fan 100 is connected via a rotation shaft 62 to the fan motor 61, which
is a drive source provided on the back surface 51d, and is driven by the fan motor 61
to rotate. The fan motor 61 applies a drive force to the axial flow fan 100.
25 [0075]
The outdoor unit body 51 has its interior divided by a divider 51g serving as a
wall into a blast room 56 in which the axial flow fan 100 is placed and a machine room
57 in which the compressor 64 or other machines are placed. In the blast room 56,
the side surface 51a and the back surface 51d are provided with a heat exchanger 68
30 extending in a substantially L shape in a plan view. The heat exchanger 68 functions
32
as the condenser 72 during heating operation and functions as the evaporator 73
during cooling operation.
[0076]
A bellmouth 63 is disposed further radially outward than the axial flow fan 100
5 disposed in the blast room 56. The bellmouth 63 is located further outward than an
outer peripheral end of each of the blades 20, and forms an annular shape along the
direction of rotation of the axial flow fan 100. Further, the divider 51g is located at
one side of the bellmouth 63, and a part of the heat exchanger 68 is located at the
other side of the bellmouth 63.
10 [0077]
The bellmouth 63 has its front edge connected to the front panel 52 of the
outdoor unit 50 so as to surround the outer periphery of the air outlet 53. The
bellmouth 6 3 may be integrated with the front panel 52 or may be prepared as a
separate entity configured to be connected to the front panel 52. A flow passage
15 between a suction side and a blowout side of the bellmouth 63 is formed by the
bellmouth 63 as an air trunk near the air outlet 53. That is, the air trunk near the air
outlet 53 is separated by the bellmouth 63 from another space in the blast room 56.
[0078]
The heat exchanger 68, which is provided at a suction side of the axial flow fan
20 100, includes a plurality of fins arranged so that plate surfaces are parallel and a
heat-transfer pipe passing through the fins in the direction in which the fins are
arranged. Refrigerant circulating through the refrigerant circuit flows through the
heat-transfer pipe. The heat exchanger 68 of the present embodiment is configured
such that the heat-transfer pipe extends in a L shape from the side surface 51a to the
25 back surface 51d of the outdoor unit body 51 and a plurality of the heat-transfer pipes
meander through the fins. Further, the heat exchanger 68 constitutes the refrigerant
circuit 71 of the air-conditioning apparatus by being connected to the compressor 64
via a pipe 65 or other pipes and further connected to an indoor-side heat exchanger,
an expansion valve, or other components (not illustrated). Further, the machine
30 room 57 accommodates a substrate box 66 containing a control substrate 67
33
configured to control the pieces of equipment mounted in the outdoor unit.
[0079]
(Working Effects of Refrigeration Cycle Apparatus 70)
Embodiment 8 brings about advantages that are similar to those of a
5 corresponding one of Embodiments 1 to 7. For example, the axial flow fans 100 to
100F inhibit the growth of a blade tip vortex at the trailing edge 22. Therefore,
mounting any one or more of these axial flow fans 100 to 100F in the air-sending
device allows the air-sending device to send an increased volume of air with low
noise and high efficiency. Further, mounting the axial flow fan 100 or other axial flow
10 fans in an air conditioner or a hot water supply outdoor unit that is the refrigeration
cycle apparatus 70 constituted by the compressor 64 and the heat exchanger or other
components makes it possible to attain a large volume of pass-by air with low noise
and high efficiency and increase the amount of heat that is exchanged in the heat
exchanger 68. Therefore, the refrigeration cycle apparatus 70 allows the pieces of
15 equipment to achieve reduced noise and improved energy conservation. Further,
mounting the axial flow fan 100 or other axial flow fans in the refrigeration cycle
apparatus 70 allows the refrigeration cycle apparatus 70 to change to a heat
exchanger 68 that is smaller than that used in a conventional axial flow fan and
contribute to a reduction in amount of refrigerant.
20 [0080]
The configurations shown in the foregoing embodiments show examples of
contents of the present disclosure and may be combined with another publicly-known
technology, and parts of the configurations may be omitted or changed, provided such
omissions and changes do not depart from the scope of the present disclosure.
25 Reference Signs List
[0081]
10: hub, 20: blade, 20A: blade, 20B: blade, 20C: blade, 20D: blade, 20E: blade,
20F: blade, 20L: blade, 21: leading edge, 22: trailing edge, 22b: basal portion, 23:
outer peripheral edge, 24: inner peripheral edge, 25: pressure surface, 25a: pressure
30 surface, 25e: pressure surface, 26: suction surface, 26a: suction surface, 26e: suction
34
surface, 30: indentation, 31: intersection portion, 32: trailing edge end portion, 33:
apex, 34: minimum thickness portion, 36: maximum thickness portion, 37: center, 38:
inner peripheral area, 39: outer peripheral area, 40: blade tip indentation, 41: notch,
42: mountain portion, 44: apex, 44a: position, 45: valley portion, 45a: position, 50:
5 outdoor unit, 51: outdoor unit body, 51a: side surface, 51b: front surface, 51c: side
surface, 51d: back surface, 51e: top surface, 51f: bottom surface, 51g: divider, 52:
front panel, 53: air outlet, 54: fan grille, 56: blast room, 57: machine room, 61: fan
motor, 62: rotation axis, 63: bellmouth, 64: compressor, 65: pipe, 66: substrate box,
67: control substrate, 68: heat exchanger, 70: refrigeration cycle apparatus, 71:
10 refrigerant circuit, 72: condenser, 72a: condenser fan, 73: evaporator, 73a: evaporator
fan, 74: expansion valve, 100: axial flow fan, 100A: axial flow fan, 100B: axial flow
fan, 100C: axial flow fan, 100D: axial flow fan, 100E: axial flow fan, 100F: axial flow
fan, 100L: axial flow fan
35
We Claim :
[Claim 1]
An axial flow fan comprising:
a hub driven to rotate and configured to serve as a rotation axis of the axial
5 flow fan; and
a blade connected to the hub, the blade having
a leading edge, and
a trailing edge,
the trailing edge having an indentation indenting toward the leading edge,
10 the indentation narrowing from the trailing edge to the leading edge, and having
an apex being a point closest to the leading edge from among the points constituting
the indentation,
the blade having, at the indentation, a maximum thickness portion at which a
thickness of the blade is maximum, and which is positioned radially inside of the
15 apex.
[Claim 2]
The axial flow fan of claim 1, wherein the maximum thickness portion is
between an inner peripheral end portion of the indentation and the apex and is closer
to the apex than a center between the inner peripheral end portion and the apex.
20 [Claim 3]
The axial flow fan of claim 1, wherein the indentation has the maximum
thickness portion at an inner peripheral end portion of the indentation.
[Claim 4]
The axial flow fan of any one of claims 1 to 3, wherein the blade has, at the
25 indentation, a minimum thickness portion at which a thickness of the blade is
minimum, and which is positioned radially outside of the apex.
[Claim 5]
The axial flow fan of claim 4, wherein the blade has, at the indentation, a
minimum thickness portion at which a thickness of the blade is minimum, and which is
30 positioned between the apex and an outer peripheral end portion of the indentation.
36
[Claim 6]
The axial flow fan of claim 4, wherein the blade has, at the indentation, a
minimum thickness portion at which a thickness of the blade is minimum, and which is
positioned at an outer peripheral end portion of the indentation.
5 [Claim 7]
The axial flow fan of any one of claims 1 to 6, wherein the indentation has a
blade tip indentation having a serrated shape along the trailing edge as a portion of
the indentation that is positioned outside of the apex.
[Claim 8]
10 The axial flow fan of any one of claims 1 to 6, wherein the indentation has
blade tip indentation having a serrated shape along the trailing edge as a portion of
the indentation that is positioned inside of the apex.
[Claim 9]
The axial flow fan of any one of claims 1 to 6, wherein the indentation has
15 blade tip indentations having serrated shapes along the trailing edge as portions of
the indentation that are positioned inside and outside of the apex.
[Claim 10]
The axial flow fan of claim 9, wherein the indentation is configured such that in
a direction in which the blade rotates, a depth of any one of notches of the blade tip
20 indentation positioned inside of the apex is greater than a depth of a notch of the
blade tip indentation positioned outside of the apex.
[Claim 11]
The axial flow fan of claim 9 or 10, wherein the indentation is configured such
that in a direction in which the blade rotates, a depth of any one of notches of the
25 blade tip indentation positioned inside of the maximum thickness portion is greater
than a depth of a notch of the blade tip indentation positioned outside of the maximum
thickness portion.
[Claim 12]
An air-sending device, comprising:
30 the axial flow fan of any one of claims 1 to 11;
37
a drive source configured to apply a drive force to the axial flow fan; and
a casing configured to house the axial flow fan and the drive source.
[Claim 13]
A refrigeration cycle apparatus, comprising:
5 the air-sending device of claim 12; and
a refrigerant circuit having a condenser and an evaporator,
the air-sending device being configured to send air to at least either the
condenser or the evaporator.
Dated this 17th day of October, 2021