FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
AXIAL 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
5 Technical Field
[0001]
The present disclosure relates to an axial fan including blades, an air-sending
device including the axial fan, and a refrigeration cycle apparatus including the airsending device.
10 Background Art
[0002]
Axial fans typically include blades disposed along the circumferential surface of
a cylindrical boss. A torque provided to the boss causes the blades to rotate to
thereby transport fluid. As the blades of such an axial fan rotate, the fluid existing
15 between the blades strikes the surface of the blades. The surface struck by the fluid
increases in pressure, which causes the fluid to be pushed out and move in the
direction of a rotation axis about which the blades rotate.
[0003]
To reduce required fan input relative to the related art, some proposed axial
20 fans of this type are designed to have a protrusion disposed on the pressure surface,
which scoops up airflow, of each blade in a direction transverse to the centrifugal
direction (see, for example, Patent Literature 1).
Citation List
Patent Literature
25 [0004]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2016-056772
Summary of Invention
Technical Problem
30 [0005]
3
In the axial fan described in Patent Literature 1, the normal to the fan surface is
directed outward in the outer area of each blade. Airflow is thus pushed out toward
the outer area of the blade as the airflow moves from the front edge to the rear edge
in the direction of rotation. The axial fan described in Patent Literature 1, however,
5 has no structure provided at the outer end of the blade to prevent leakage of airflow.
This means that as airflow moves along the pressure surface of the blade from the
front edge toward the rear edge, a large proportion of the airflow leaks out of the
blade from the outer edge of the blade. Therefore, the axial fan described in Patent
Literature 1 does not allow the airflow received at the front edge of the blade to easily
10 flow, in the direction of rotation of the blade, through the outer area of the pressure
surface where force is efficiently imparted from the blade to the airflow.
[0006]
The present disclosure aims to address the above-mentioned problem.
Accordingly, it is an object of the present disclosure to provide an axial fan that allows
15 the airflow received at the front edge of each blade to easily flow, in the direction of
rotation of the blade, through the outer area of the pressure surface where force is
efficiently imparted from the blade to the airflow, an air-sending device including the
axial fan, and a refrigeration cycle apparatus including the air-sending device.
Solution to Problem
20 [0007]
An axial fan according to an embodiment of the present disclosure includes a
hub and blades. The hub has a rotating shaft, and is configured to be driven to
rotate. The blades are provided to the hub, and each have a front edge portion and
a rear edge portion. In a state in which the blades rotate to generate an airflow, the
25 front edge portion is placed most upstream in the airflow, and the rear edge portion is
placed most downstream in the airflow. In a shape of the blades rotated and
projected onto a meridian plane that covers shapes of the blades and a shape of the
rotating shaft, the front edge portion has an outline represented by a front-edge
projected portion having a first recess portion formed in a recessed shape that
30 recedes upstream in the airflow, the rear edge portion has an outline represented by a
4
rear-edge projected portion having a second recess portion formed in a recessed
shape that recedes upstream in the airflow, and the first recess portion has at least a
portion that is formed further radially inside than is the second recess portion.
[0008]
5 An air-sending device according to an embodiment of the present disclosure
includes the axial fan configured as described above, a drive source configured to
provide a drive force to the axial fan, and a casing that accommodates the axial fan
and the drive source.
[0009]
10 A refrigeration cycle apparatus according to an embodiment of the present
disclosure includes the air-sending device configured as described above, and a
refrigerant circuit having a condenser and an evaporator. The air-sending device is
configured to send air to at least one of the condenser and the evaporator.
Advantageous Effects of Invention
15 [0010]
According to an embodiment of the present disclosure, the second recess
portion of the rear-edge projected portion is formed further radially outside than is the
first recess portion of the front-edge projected portion, and the first recess portion has
at least a portion that is formed further radially inside than is the second recess
20 portion. As a result, the airflow along the pressure surface of each blade is directed
radially outward as the airflow proceeds from the first recess portion of the front edge
portion toward the second recess portion of the rear edge portion. This allows the
airflow received at the front edge of the blade to easily flow, in the direction of blade
rotation, through the outer area of the pressure surface where force is efficiently
25 imparted from the blade to the airflow.
Brief Description of Drawings
[0011]
[Fig. 1] Fig. 1 is a schematic perspective view of an axial fan according to
Embodiment 1.
5
[Fig. 2] Fig. 2 illustrates an exemplary shape of the axial fan according to
Embodiment 1 that is rotated and projected onto a meridian plane MP depicted in Fig.
1.
[Fig. 3] Fig. 3 illustrates another exemplary shape of the axial fan according to
5 Embodiment 1 that is rotated and projected onto the meridian plane MP depicted in
Fig. 1.
[Fig. 4] Fig. 4 is a perspective view of the axial fan according to Embodiment 1
for specifying various cross-section locations in the axial fan.
[Fig. 5] Fig. 5 illustrates cross-section locations A, B, and C in the axial fan
10 depicted in Fig. 4 that are rotated and projected onto the meridian plane MP.
[Fig. 6] Fig. 6 illustrates respective cross-sections of a blade taken at the crosssection locations A, B, and C, as viewed in a direction perpendicular to a rotating
shaft RS.
[Fig. 7] Fig. 7 illustrates an exemplary end face of a blade as viewed in the
15 direction perpendicular to the rotating shaft RS.
[Fig. 8] Fig. 8 is a perspective view of a recessed passage of the axial fan
according to Embodiment 1.
[Fig. 9] Fig. 9 illustrates a meridian plane schematically showing airflow through
a blade of the axial fan according to Embodiment 1.
20 [Fig. 10] Fig. 10 illustrates a meridian plane schematically showing airflow
through a blade of the axial fan according to a modification of Embodiment 1.
[Fig. 11] Fig. 11 illustrates an exemplary shape of an axial fan according to
Embodiment 2 that is rotated and projected onto a meridian plane.
[Fig. 12] Fig. 12 illustrates an exemplary shape of an axial fan according to
25 Embodiment 3 that is rotated and projected onto a meridian plane.
[Fig. 13] Fig. 13 illustrates an exemplary shape of an axial fan according to
Embodiment 4 that is rotated and projected onto a meridian plane.
[Fig. 14] Fig. 14 is a schematic perspective view of an axial fan according to
Embodiment 5.
6
[Fig. 15] Fig. 15 illustrates an exemplary shape of an axial fan according to
Embodiment 6 that is rotated and projected onto a meridian plane.
[Fig. 16] Fig. 16 illustrates an exemplary shape of an axial fan according to
Embodiment 7 that is rotated and projected onto a meridian plane.
5 [Fig. 17] Fig. 17 is a perspective view of an axial fan according to a
comparative example, illustrating how airflow blows from the axial fan.
[Fig. 18] Fig. 18 is a perspective view of the axial fan according to Embodiment
7, illustrating how airflow blows from the axial fan.
[Fig. 19] Fig. 19 is a schematic perspective view of an axial fan according to
10 Embodiment 8.
[Fig. 20] Fig. 20 is a schematic perspective view of an axial fan according to
Embodiment 9.
[Fig. 21] Fig. 21 is a schematic diagram of a refrigeration cycle apparatus
according to Embodiment 10.
15 [Fig. 22] Fig. 22 is a perspective view, as seen from an air outlet, of an outdoor
unit used as an air-sending device.
[Fig. 23] Fig. 23 is a top view of an outdoor unit for explaining the configuration
of the outdoor unit.
[Fig. 24] Fig. 24 illustrates the outdoor unit with a fan grille removed from the
20 outdoor unit.
[Fig. 25] Fig. 25 illustrates the internal configuration of the outdoor unit with the
fan grille, a front panel, and other components removed from the outdoor unit.
Description of Embodiments
[0012]
25 An axial fan, an air-sending device, and a refrigeration cycle apparatus
according to embodiments will be described below with reference to the drawings.
In the drawings below including Fig. 1, the relative dimensions, shapes, and other
details of various components may differ from the actuality. In the drawings below,
the same reference signs are used to indicate the same or corresponding elements or
30 features throughout the specification. Although terms representing directions (e.g.,
7
"upper", "lower", "right", "left", "front", or "rear") are used as appropriate to facilitate
understanding, such terms are for illustrative purposes only and not intended to limit
the corresponding apparatus, device, or component to any particular placement or
orientation.
5 [0013]
Embodiment 1
[Axial Fan 100]
Fig. 1 is a schematic perspective view of an axial fan 100 according to
Embodiment 1. A rotation direction DR represented by an arrow in Fig. 1 represents
10 the direction of rotation DR of the axial fan 100. An open arrow in Fig. 1 represents
the direction of airflow FL. In the direction of airflow FL, with the axial fan 100 used
as positional reference, Z1 represents an area located upstream in the airflow with
the axial fan 100 used as positional reference, and Z2 represents an area located
downstream in the airflow with the axial fan 100 used as positional reference. That
15 is, Z1 represents the air suction side with the axial fan 100 used as positional
reference, and Z2 represents the air blow side with the axial fan 100 used as
positional reference. The Y-axis represents radial direction from a rotating shaft RS
of the axial fan 100. With the axial fan 100 used as positional reference, Y2
represents the radially inner area (to be referred to simply as "inner area" hereinafter)
20 of the axial fan 100, and Y1 represents the radially outer area (to be referred to simply
as "outer area" hereinafter) of the axial fan 100.
[0014]
The axial fan according to Embodiment 1 is described below with reference to
Fig. 1. The axial fan 100 is used for, for example, an air-conditioning apparatus or a
25 ventilator. As illustrated in Fig. 1, the axial fan 100 includes a hub 10 disposed on
the rotating shaft RS, and blades 20 provided to the hub 10.
[0015]
(Hub 10)
The hub 10 is driven to rotate, and defines the rotating shaft RS. The hub 10
30 rotates about the rotating shaft RS. The rotation direction DR of the axial fan 100 is
8
a clockwise direction indicated by an arrow in Fig. 1. However, the rotation direction
DR of the axial fan 100 may not necessarily be the clockwise direction. Alternatively,
the axial fan 100 may be configured to rotate in a counterclockwise direction by
changing the angle at which the blades 20 are mounted. The hub 10 is connected to
5 the rotating shaft of a drive source such as a motor (not illustrated). In one example,
the hub 10 may have a cylindrical shape, or may have a plate-like shape. The hub
10 is not limited to any particular shape as long as the hub 10 is connected to the
rotating shaft of the drive source as mentioned above.
[0016]
10 (Blades 20)
The blades 20 extend radially outward from the hub 10. The blades 20 are
circumferentially spaced apart from each other. Although Embodiment 1 is directed
to an exemplary case where there are three blades 20, the number of blades 20 is not
limited to three. In the direction of airflow FL, the upstream surface (surface near
15 Z1) of each blade 20 is referred to as suction surface 26, and the downstream surface
(surface near Z2) of the blade 20 is referred to as pressure surface 25. A surface of
the blade 20 depicted on the near side of Fig. 1 corresponds to the pressure surface
25, and a surface of the blade 20 depicted on the far side of Fig. 1 corresponds to the
suction surface 26.
20 [0017]
The blade 20 has a front edge portion 21, a rear edge portion 22, an outer
edge portion 23, and an inner edge portion 24. The front edge portion 21 is placed
upstream (near Z1) in the airflow to be generated, and formed at the leading side of
the blade 20 in the rotation direction DR. That is, the front edge portion 21 is placed
25 forward of the rear edge portion 22 in the rotation direction DR. The rear edge
portion 22 is placed downstream (near Z2) in the airflow to be generated, and formed
at the trailing side of the blade 20 in the rotation direction DR. That is, the rear edge
portion 22 is placed rearward of the front edge portion 21 in the rotation direction DR.
The axial fan 100 has the front edge portion 21, which is a blade end portion oriented
9
in the rotation direction DR of the axial fan 100, and the rear edge portion 22, which is
a blade end portion opposite to the front edge portion 21 in the rotation direction DR.
[0018]
The outer edge portion 23 extends in the front-rear direction and in arcuate
5 form such that the outer edge portion 23 connects the outermost part of the front
edge portion 21 with the outermost part of the rear edge portion 22. The outer edge
portion 23 is located in an end portion of the axial fan 100 in the radial direction (Yaxis direction). The inner edge portion 24 extends in the front-rear direction and in
arcuate form such that the inner edge portion 24 connects the innermost part of the
10 front edge portion 21 with the innermost part of the rear edge portion 22. The inner
edge portion 24 of the blade 20 is connected to the periphery of the hub 10.
[0019]
Fig. 2 illustrates an exemplary shape of the axial fan 100 according to
Embodiment 1 that is rotated and projected onto a meridian plane MP depicted in Fig.
15 1. Fig. 3 illustrates another exemplary shape of the axial fan 100 according to
Embodiment 1 that is rotated and projected onto the meridian plane MP depicted in
Fig. 1. Figs. 2 and 3 each illustrate a shape of each blade 20 of the axial fan 100
rotated and projected onto the meridian plane MP that covers the shape of the
rotating shaft RS and the shapes of the blades 20. For the axial fan 100, a shape of
20 each blade 20 that is rotated and projected onto the meridian plane MP is
represented by a blade projected portion 20a, and a shape of the hub 10 that is
rotated and projected onto the meridian plane MP is represented by a hub projected
portion 10a.
[0020]
25 As illustrated in Figs. 2 and 3, in the meridian plane MP in which the horizontal
axis represented by the Y-axis is defined as radial direction, and the vertical axis
represented by the Z-axis is defined as the axial direction of the rotating shaft RS, the
front edge portion 21 is located below the rear edge portion 22, and the rear edge
portion 22 is located above the front edge portion 21. The front edge portion 21 and
10
the rear edge portion 22 are each defined by a curve connecting a base portion 11,
which is the root joint of the blade 20 with the hub 10, and the outer edge portion 23.
[0021]
(Front Edge Portion 21)
5 The front edge portion 21 defines, in the meridian plane MP onto which the
front edge portion 21 is rotated and projected, a front-edge projected portion 21a
formed by a curve including an S-shaped portion. The front-edge projected portion
21a is formed by an S-shaped curve that arcs upstream (toward Z1) and downstream
(toward Z2) with the axial fan 100 used as positional reference.
10 [0022]
The front-edge projected portion 21a has a front edge inflection-point portion
Sf1, which is a point of inflection of the S-shape. In a direction perpendicular to the
rotating shaft RS, that is, in the radial direction of the axial fan 100, the front edge
inflection-point portion Sf1 is formed closer to the outer edge portion 23 than is the
15 middle position ML of a straight line L1, which connects the hub 10 and the outer
edge portion 23.
[0023]
(Front-Edge Recess Portion 120a)
The front edge portion 21 has a front-edge recess portion 120a. In the outline
20 of the front edge portion 21 represented by the front-edge projected portion 21a, the
front-edge recess portion 120a is formed in a protruding shape that protrudes
upstream (toward Z1) in the airflow. As illustrated in Figs. 2 and 3, the front edge
portion 21 has an outline represented by the front-edge projected portion 21a that has
the front-edge recess portion 120a formed in a protruding shape that protrudes
25 upstream in the airflow. The front-edge recess portion 120a corresponds to a first
recess portion of the axial fan 100. In the front-edge projected portion 21a, the frontedge recess portion 120a is formed between a front-edge base portion 11a, which is
the root joint of the front edge portion 21 with the hub 10, and the front edge
inflection-point portion Sf1. In the front-edge projected portion 21a, the front-edge
30 recess portion 120a forms an arc that protrudes upstream (toward Z1). In other
11
words, in the front-edge recess portion 120a of the front edge portion 21, the pressure
surface 25 forms an arc that recedes upstream (toward Z1). That is, in the frontedge recess portion 120a, the pressure surface 25 is formed in a recessed shape that
opens downstream (toward Z2). In the front-edge recess portion 120a of the front
5 edge portion 21, the suction surface 26 forms an arc that protrudes upstream (toward
Z1).
[0024]
The front edge portion 21 further has a front-edge ridge portion 121. In the
front-edge projected portion 21a, the front-edge ridge portion 121 is formed so as to
10 recede downstream (toward Z2). As illustrated in Figs. 2 and 3, the front-edge
projected portion 21a has the front-edge ridge portion 121 that recedes downstream
(toward Z2). In the front-edge projected portion 21a, the front-edge ridge portion 121
forms an arc that recedes downstream (toward Z2). In other words, in the front-edge
ridge portion 121 of the front edge portion 21, the pressure surface 25 forms an arc
15 that protrudes downstream (toward Z2). That is, in the front-edge ridge portion 121
of the front edge portion 21, the suction surface 26 is formed in a recessed shape that
opens upstream (toward Z1).
[0025]
In the front-edge projected portion 21a, the front-edge recess portion 120a and
20 the front-edge ridge portion 121 are formed in this order from the inner area toward
the outer area in the radial direction of the axial fan 100. The front-edge projected
portion 21a has, in the radial direction, a proportion of the front-edge recess portion
120a corresponding to the first recess portion that is greater than a proportion of the
front-edge ridge portion 121. In other words, the front-edge projected portion 21a
25 has, in the radial direction, a proportion of the front-edge recess portion 120a
corresponding to the first recess portion that is greater than a proportion of a portion
formed in a recessed shape that recedes downstream in the airflow.
[0026]
A first plane FHS is now defined as an imaginary plane perpendicular to the
30 rotating shaft RS and passing through the front-edge base portion 11a, which is the
12
root joint of the front edge portion 21 with the hub 10. A point on the front-edge ridge
portion 121 located closest to the first plane FHS is defined as a maximum-point
portion 121a. The maximum-point portion 121a is located most downstream in the
front-edge ridge portion 121. In the direction perpendicular to the rotating shaft RS,
5 that is, in the radial direction of the axial fan 100, the maximum-point portion 121a is
formed closer to the outer edge portion 23 than is the middle position ML of the
straight line L1, which connects the hub 10 and the outer edge portion 23.
[0027]
As illustrated in Figs. 2 and 3, the front-edge recess portion 120a is formed
10 further inside than is the maximum-point portion 121a. A point on the front-edge
recess portion 120a located farthest from the first plane FHS is defined as a front
edge minimum-point portion Mn1. The front edge minimum-point portion Mn1
corresponds to a first minimum-point portion of the axial fan 100. The front edge
minimum-point portion Mn1 is located further upstream (toward Z2) than is the
15 maximum-point portion 121a. The front edge minimum-point portion Mn1
corresponding to the first minimum-point portion is located at a position on the frontedge recess portion 120a that is most upstream (toward Z1) in the airflow. The
distance FH1 between the first plane FHS and the front edge minimum-point portion
Mn1 is greater than the distance FH2 between the first plane FHS and the maximum20 point portion 121a.
[0028]
(Rear Edge Portion 22)
The rear edge portion 22 defines, in the meridian plane MP onto which the rear
edge portion 22 is rotated and projected, a rear-edge projected portion 22e formed by
25 a curve including S-shaped portions. The rear-edge projected portion 22e has a first
S-shaped portion 22a, and a second S-shaped portion 22b. The first S-shaped
portion 22a and the second S-shaped portion 22b of the rear-edge projected portion
22e are each formed by an S-shaped curve that arcs upstream (toward Z1) and
downstream (toward Z2) in the airflow. The rear-edge projected portion 22e is
13
formed by a curve that is a combination of the first S-shaped portion 22a and the
second S-shaped portion 22b.
[0029]
The rear-edge projected portion 22e has a rear edge first-inflection-point
5 portion Se1, which is a point of inflection of the first S-shaped portion 22a, and a rear
edge second-inflection-point portion Se2, which is a point of inflection of the second
S-shaped portion 22b. In the direction perpendicular to the rotating shaft RS, that is,
in the radial direction of the axial fan 100, the rear edge second-inflection-point
portion Se2 is formed closer to the outer edge portion 23 than is the middle position
10 ML of the straight line L1, which connects the hub 10 and the outer edge portion 23.
In the direction perpendicular to the rotating shaft RS, that is, in the radial direction of
the axial fan 100, the rear edge first-inflection-point portion Se1 is formed further
inside than is the rear edge second-inflection-point portion Se2.
[0030]
15 (Rear Edge Recess Portion 120b)
The rear edge portion 22 has a rear-edge recess portion 120b. The rear-edge
recess portion 120b is formed in a recessed shape that recedes upstream in the
airflow. As illustrated in Figs. 2 and 3, the rear edge portion 22 has an outline
represented by the rear-edge projected portion 22e that has the rear-edge recess
20 portion 120b formed in a recessed shape that recedes upstream (toward Z1) in the
airflow. The rear-edge recess portion 120b corresponds to a second recess portion
of the axial fan 100. In the rear-edge projected portion 22e, the rear-edge recess
portion 120b is formed between the rear edge first-inflection-point portion Se1 and the
rear edge second-inflection-point portion Se2. In the rear-edge projected portion
25 22e, the rear-edge recess portion 120b forms an arc that recedes upstream (toward
Z1). In other words, in the rear-edge recess portion 120b of the rear edge portion
22, the pressure surface 25 forms an arc that recedes upstream (toward Z1). That
is, in the rear-edge recess portion 120b, the pressure surface 25 is formed in a
recessed shape that opens downstream (toward Z2). In the rear-edge recess
14
portion 120b of the rear edge portion 22, the suction surface 26 forms an arc that
protrudes upstream (toward Z1).
[0031]
The rear edge portion 22 further has a first ridge portion 122a, and a second
5 ridge portion 122b. The first ridge portion 122a and the second ridge portion 122b
are formed so as to protrude downstream (toward Z2). As illustrated in Figs. 2 and
3, the rear-edge projected portion 22e has the first ridge portion 122a that forms an
arc protruding downstream (toward Z2). The rear-edge projected portion 22e has
the second ridge portion 122b that forms an arc protruding downstream (toward Z2).
10 In the front-edge projected portion 21a, the first ridge portion 122a and the second
ridge portion 122b each form an arc that protrudes downstream (toward Z2). In
other words, in the first ridge portion 122a and the second ridge portion 122b of the
rear edge portion 22, the pressure surface 25 forms an arc that protrudes
downstream (toward Z2). That is, in the first ridge portion 122a and the second ridge
15 portion 122b of the rear edge portion 22, the suction surface 26 is formed in a
recessed shape that opens upstream (toward Z1). The rear-edge recess portion
120b is formed between the first ridge portion 122a and the second ridge portion
122b. In the rear-edge projected portion 22e, the first ridge portion 122a, the rearedge recess portion 120b, and the second ridge portion 122b are formed in this order
20 from the inner area toward the outer area in the radial direction of the axial fan 100.
[0032]
A second plane BHS is now defined as an imaginary plane perpendicular to the
rotating shaft RS and passing through a rear-edge base portion 11b, which is the root
joint of the rear edge portion 22 with the hub 10. A point on the first ridge portion
25 122a located farthest from the second plane BHS is defined as a first maximum-point
portion 123a. The first maximum-point portion 123a is located most downstream in
the first ridge portion 122a. Likewise, a point on the second ridge portion 122b
located farthest from the second plane BHS is defined as a second maximum-point
portion 123b. The second maximum-point portion 123b is located most downstream
30 in the second ridge portion 122b. The distance BH2 between the second plane BHS
15
and the second maximum-point portion 123b is greater than the distance BH1
between the second plane BHS and the first maximum-point portion 123a. That is,
the distance BH1 between the second plane BHS and the first maximum-point portion
123a is less than the distance BH2 between the second plane BHS and the second
5 maximum-point portion 123b. The second maximum-point portion 123b is located
further downstream (toward Z2) than is the first maximum-point portion 123a. In the
direction perpendicular to the rotating shaft RS, that is, in the radial direction of the
axial fan 100, the second maximum-point portion 123b is formed closer to the outer
edge portion 23 than is the middle position ML of the straight line L1, which connects
10 the hub 10 and the outer edge portion 23.
[0033]
As illustrated in Figs. 2 and 3, the rear-edge recess portion 120b is formed
between the first maximum-point portion 123a and the second maximum-point portion
123b. A point on the rear-edge recess portion 120b located closest to the second
15 plane BHS is defined as a rear edge minimum-point portion Mn2. The rear edge
minimum-point portion Mn2 corresponds to a second minimum-point portion of the
axial fan 100. The rear edge minimum-point portion Mn2 corresponding to the
second minimum-point portion is located at a position on the rear-edge recess portion
120b that is most upstream (toward Z1) in the airflow. The rear edge minimum-point
20 portion Mn2 is located further upstream (toward Z1) than are the first maximum-point
portion 123a and the second maximum-point portion 123b. The distance BH3
between the second plane BHS and the rear edge minimum-point portion Mn2 is less
than the distance BH1 between the second plane BHS and the first maximum-point
portion 123a. The distance BH3 between the second plane BHS and the rear edge
25 minimum-point portion Mn2 is less than the distance BH2 between the second plane
BHS and the second maximum-point portion 123b.
[0034]
As illustrated in Figs. 2 and 3, the rear-edge recess portion 120b, which
corresponds to the second recess portion of the axial fan 100, is formed radially
30 closer to the outer edge portion 23 than is the front-edge recess portion 120a, which
16
corresponds to the first recess portion of the axial fan 100. The front-edge recess
portion 120a, which corresponds to the first recess portion of the axial fan 100, has at
least a portion that is formed closer to the inner edge portion 24 than is the rear-edge
recess portion 120b, which corresponds to the second recess portion of the axial fan
5 100.
[0035]
The middle position of the radial width of the front-edge recess portion 120a is
now defined as a front-edge-side middle portion Aa. That is, in the radial direction of
the axial fan 100, the midpoint of the distance between the front-edge base portion
10 11a and the front edge inflection-point portion Sf1 is defined as the front-edge-side
middle portion Aa. The middle position of the radial width of the rear-edge recess
portion 120b is defined as a rear-edge-side middle portion Ab. That is, in the radial
direction of the axial fan 100, the midpoint of the distance between the rear edge firstinflection-point portion Se1 and the rear edge second-inflection-point portion Se2 is
15 defined as the rear-edge-side middle portion Ab. As illustrated in Figs. 2 and 3, in
the radial direction of the axial fan 100, the rear-edge-side middle portion Ab is
located further outside than is the front-edge-side middle portion Aa. In one
example, the front-edge-side middle portion Aa may be different from the front edge
minimum-point portion Mn1 as illustrated in Fig. 2, and in another example, the front20 edge-side middle portion Aa may be the same as the front edge minimum-point
portion Mn1 as illustrated in Fig. 3.
[0036]
(Relationship between Meridian Plane, and Front-Edge Recess Portion 120a and
Rear-Edge Recess Portion 120b)
25 Fig. 4 is a perspective view of the axial fan 100 according to Embodiment 1 for
specifying various cross-section locations in the axial fan 100. A cross-section
location A, a cross-section location B, and a cross-section location C depicted in Fig.
4 each represent a location at which the corresponding cross-section of the blade 20
is taken in the rotation direction DR. Fig. 5 illustrates the cross-section locations A,
30 B, and C in the axial fan 100 depicted in Fig. 4 that are rotated and projected onto the
17
meridian plane MP. Fig. 6 illustrates respective cross-sections of the blade 20 taken
at the cross-section locations A, B, and C, as viewed in the direction perpendicular to
the rotating shaft RS. Fig. 7 illustrates an exemplary end face of the blade 20 as
viewed in the direction perpendicular to the rotating shaft RS. The expression "as
5 viewed in the direction perpendicular to the rotating shaft RS" means being viewed in
a direction indicated by an open arrow VP in Fig. 5. The relationship between the
meridian plane, and the front-edge recess portion 120a and the rear-edge recess
portion 120b is described below with reference to Figs. 4 to 7.
[0037]
10 As illustrated in Figs. 4 to 7, the blade 20 is sloped such that the front edge
portion 21 is located upstream (toward Z1) in the airflow, and that the rear edge
portion 22 is located downstream (toward Z2) in the airflow. As illustrated in Figs. 6
and 7, in the rotation direction DR, the blade 20 is cambered in an arc that recedes
upstream (toward Z1) in the airflow. As illustrated in Fig. 7, a straight line connecting
15 the front edge portion 21 and the rear edge portion 22 of the blade 20 is defined as
chord length WL, and the distance between the chord length WL and the pressure
surface 25 of the blade 20 is defined as camber height WH. As illustrated in Fig. 6,
the blade cross-section taken at the cross-section location B is located most
upstream (toward Z1) among the cross-sections of the blade 20 taken at the cross20 section locations A, B, and C. That is, at the cross-section location B, the blade 20 is
formed in a recessed shape that recedes from the cross-section location A and the
cross-section location C. As illustrated in Fig. 6, the chord length WL of the blade 20
increases in the following order: the cross-section location A, the cross-section
location B, and the cross-section location C. That is, in a portion of the blade 20
25 from the cross-section location A to the cross-section location C in the radial direction,
the chord length WL progressively increases as the blade 20 extends outward. The
above-mentioned relationship among the respective chord lengths WL at the crosssection locations A, B, and C is intended to be illustrative only and not limiting.
[0038]
18
The front-edge recess portion 120a of the axial fan 100 can be defined in the
meridian plane by the following features: the chord length WL and camber height WH
of the blade 20 as illustrated in Fig. 7; and the locations in the front edge portion 21
such as the cross-section locations A, B, and C in the axial direction of the rotating
5 shaft RS as illustrated in Fig. 6. The rear-edge recess portion 120b of the axial fan
100 can be defined in the meridian plane by the following features: the chord length
WL and camber height WH of the blade 20 as illustrated in Fig. 7; and the locations in
the rear edge portion 22 such as the cross-section locations A, B, and C in the axial
direction of the rotating shaft RS as illustrated in Fig. 6.
10 [0039]
(Recessed Passage 120)
Fig. 8 is a perspective view of a recessed passage 120 of the axial fan 100
according to Embodiment 1. As illustrated in Fig. 8, the pressure surface 25 of the
blade 20 has the recessed passage 120 formed in a recessed shape that recedes
15 upstream (toward Z1) in the airflow. The recessed passage 120 defines, on the
pressure surface 25 of the blade 20, a passage through which air flows. In the
recessed passage 120, the pressure surface 25 is formed in a recessed shape that
recedes upstream (toward Z1) in an arc in the radial direction of the axial fan 100.
Further, in the recessed passage 120, the suction surface 26 is formed in a protruding
20 shape that protrudes upstream (toward Z1) in an arc in the radial direction of the axial
fan 100. That is, a wall of the blade 20 that defines the recessed passage 120 is
curved so as to protrude upstream (toward Z1).
[0040]
The recessed passage 120 is formed between the front edge portion 21 and
25 the rear edge portion 22. The recessed passage 120 extends continuously from the
front edge portion 21 to the rear edge portion 22 in the rotation direction DR of the
axial fan 100. In the circumferential direction, the recessed passage 120 has an end
portion near the front edge portion 21 that is defined by a portion of the recessed
passage 120 that defines the front-edge recess portion 120a, and the recessed
30 passage 120 has an end portion near the rear edge portion 22 that is defined by a
19
portion of the recessed passage 120 that defines the rear-edge recess portion 120b.
That is, the recessed passage 120 includes, in opposite end portions in the rotation
direction DR of the axial fan 100, a portion defining the front-edge recess portion
120a and a portion defining the rear-edge recess portion 120b, and defines a
5 passage through which airflow passes between the front-edge recess portion 120a
and the rear-edge recess portion 120b.
[0041]
[Operation of Axial Fan 100]
Fig. 9 illustrates a meridian plane schematically showing airflow through each
10 blade 20 of the axial fan 100 according to Embodiment 1. The flow of air through the
blade 20 of the axial fan 100 is described below with reference to Figs. 8 and 9. The
direction FL indicated by arrows represents the direction of airflow. As illustrated in
Fig. 8, the recessed passage 120 is used as a passage for airflow on the pressure
surface 25 of the blade 20. As the blade 20 rotates about the rotating shaft RS
15 driven by a motor or another drive device coupled to the axial fan 100, the pressure
surface 25 of the blade 20 receives air. Then, as illustrated in Figs. 8 and 9, the
airflow entering through the front-edge recess portion 120a of the front edge portion
21 passes through and moves along the recessed passage 120. At this time, the
airflow is directed outward in the radial direction of the axial fan 100 as the airflow
20 moves along the recessed passage 120 from the front-edge recess portion 120a of
the front edge portion 21 toward the rear-edge recess portion 120b of the rear edge
portion 22. Due to the movement of airflow from the inner area toward the outer
area in the radial direction of the axial fan 100, energy resulting from a difference in
angular momentum associated with a change in radius is provided from the blade 20
25 to the gas.
[0042]
Fig. 10 illustrates a meridian plane schematically showing airflow through the
blade 20 of the axial fan 100 according to a modification of Embodiment 1. In the
axial fan 100 described above with reference to Fig. 9, the rear edge second30 inflection-point portion Se2 and the front edge inflection-point portion Sf1 are located
20
at substantially the same radial position from the rotating shaft RS. In contrast, in
the axial fan 100 illustrated in Fig. 10, the rear edge second-inflection-point portion
Se2 and the front edge inflection-point portion Sf1 are located at different radial
positions from the rotating shaft RS. More specifically, in the axial fan 100 illustrated
5 in Fig. 10, the front edge inflection-point portion Sf1 is located further radially inside,
that is, closer to the rotating shaft RS, than is the rear edge second-inflection-point
portion Se2. The front edge inflection-point portion Sf1 is located radially between
the rear edge first-inflection-point portion Se1 and the rear edge second-inflectionpoint portion Se2. The axial fan 100 illustrated in Fig. 10 thus allows more airflow to
10 be directed radially outward than does the axial fan 100 illustrated in Fig. 9. As a
result, the energy resulting from a difference in angular momentum (= radius 
momentum) associated with a change in radius is greater for the axial fan 100
illustrated in Fig. 10 than for the axial fan 100 illustrated in Fig. 9.
[0043]
15 [Advantageous Effects of Axial Fan 100]
In the axial fan 100, the rear-edge recess portion 120b corresponding to the
second recess portion is formed further radially outside than is the front-edge recess
portion 120a corresponding to the first recess portion, and the front-edge recess
portion 120a has at least a portion that is formed further radially inside than is the
20 rear-edge recess portion 120b. Consequently, the airflow along the pressure surface
25 of the blade 20 is directed radially outward as the airflow proceeds from the frontedge recess portion 120a of the front edge portion 21 toward the rear-edge recess
portion 120b of the rear edge portion 22. In this regard, generally speaking, when an
axial fan pushes out gas in the outer area of the blades, a greater moment is imparted
25 to the gas from the blades for the same rotation frequency of the axial fan than a
moment when the axial fan pushes out the gas in the inner area of the blades. It is
therefore desired for an axial fan to direct airflow toward and through the outer area of
the blades. The configuration of the axial fan 100 mentioned above allows the
airflow received at the front edge portion 21 of the blade 20 to easily flow, in the
30 direction of rotation of the blade 20, through the outer area of the pressure surface 25
21
where force is efficiently imparted from the blade 20 to the airflow. In this regard,
gas flowing along the pressure surface 25 of the blade 20 of the axial fan 100 can
obtain the energy of momentum due to movement of the gas from the inner area
toward the outer area in the radial direction. This leads to increased flow rate. As a
5 result, the axial fan 100 is able to efficiently send air, which leads to reduced power
consumption.
[0044]
The front-edge recess portion 120a is formed between the base portion 11,
which is the root joint of the front edge portion 21 with the hub 10, and the front edge
10 inflection-point portion Sf1. The rear-edge recess portion 120b is formed between
the rear edge first-inflection-point portion Se1 and the rear edge second-inflectionpoint portion Se2. Consequently, the airflow along the pressure surface 25 of the
blade 20 is directed radially outward as the airflow proceeds from the front-edge
recess portion 120a of the front edge portion 21 toward the rear-edge recess portion
15 120b of the rear edge portion 22. The configuration of the axial fan 100 mentioned
above allows the airflow received at the front edge portion 21 of the blade 20 to easily
flow, in the direction of rotation of the blade 20, through the outer area of the pressure
surface 25 where force is efficiently imparted from the blade 20 to the airflow. In this
regard, gas flowing along the pressure surface 25 of the blade 20 of the axial fan 100
20 can obtain the energy of momentum due to movement of the gas from the inner area
toward the outer area in the radial direction. This leads to increased flow rate. As a
result, the axial fan 100 is able to efficiently send air, which leads to reduced power
consumption.
[0045]
25 The front edge inflection-point portion Sf1 is located radially between the rear
edge first-inflection-point portion Se1 and the rear edge second-inflection-point
portion Se2. Due to the above-mentioned configuration, the front edge portion 21 is
located further inside than is the rear edge portion 22. The recessed passage 120 is
thus formed in the pressure surface 25 such that the location of the recessed
30 passage 120 moves from the inner area toward the outer area as the recessed
22
passage 120 extends from the front edge portion 21 to the rear edge portion 22.
This causes the airflow over the pressure surface 25 to move from the inner area
toward the outer area as the airflow proceeds from the front edge portion 21 to the
rear edge portion 22. The airflow is thus able to obtain the energy of momentum
5 resulting from a difference in radius. This leads to increased flow rate. As a result,
the axial fan 100 is able to efficiently send air, which leads to reduced power
consumption.
[0046]
The front-edge projected portion 21a has, in the radial direction, a proportion of
10 the front-edge recess portion 120a corresponding to the first recess portion that is
greater than a proportion of a portion formed in a recessed shape that recedes
downstream in the airflow. The blade 20 of the axial fan 100 thus has a surface
having a recessed shape (bowl-like shape) that recedes downstream. This makes it
easier to scoop up airflow, which allows for increased airflow into the axial fan 100.
15 The downwardly recessed shape helps to reduce the chances of leakage of airflow
from the outer edge of the axial fan 100. This allows the airflow to be easily retained
from the front edge portion 21 to the rear edge portion 22.
[0047]
The recessed passage 120 is formed between the front edge portion 21 and
20 the rear edge portion 22. In the circumferential direction, the recessed passage 120
has an end portion near the front edge portion 21 that is defined by a portion of the
recessed passage 120 that defines the front-edge recess portion 120a, and the
recessed passage 120 has an end portion near the rear edge portion 22 that is
defined by a portion of the recessed passage 120 that defines the rear-edge recess
25 portion 120b. The configuration of the axial fan 100 mentioned above allows the
airflow received at the front edge portion 21 of the blade 20 to easily flow, in the
direction of rotation of the blade 20, through the outer area of the pressure surface 25
where force is efficiently imparted from the blade 20 to the airflow. In this regard,
gas flowing along the pressure surface 25 of the blade 20 of the axial fan 100 can
30 obtain the energy of momentum due to movement of the gas from the inner area
23
toward the outer area in the radial direction. This leads to increased flow rate. As a
result, the axial fan 100 is able to efficiently send air, which leads to reduced power
consumption.
[0048]
5 Embodiment 2
Fig. 11 illustrates an exemplary shape of an axial fan 100A according to
Embodiment 2 that is rotated and projected onto a meridian plane. Parts identical in
configuration to those of the axial fan 100A illustrated in Figs. 1 to 10 are given the
same reference signs and not described below in further detail. For the axial fan
10 100A according to Embodiment 2, a front-edge recess portion 120a1 and a rear-edge
recess portion 120b1 differ in configuration from the front-edge recess portion 120a
and the rear-edge recess portion 120b of the axial fan 100 according to Embodiment
1. The following description of the axial fan 100A according to Embodiment 2 will
thus mainly focus on the configurations of the front-edge recess portion 120a1 and
15 the rear-edge recess portion 120b1.
[0049]
(Front-Edge Recess Portion 120a1)
The front edge portion 21 has the front-edge recess portion 120a1. In an
outline of the front edge portion 21 represented by the front-edge projected portion
20 21a, the front-edge recess portion 120a1 is formed in a protruding shape that
protrudes upstream (toward Z1) in the airflow. As illustrated in Fig. 11, the front edge
portion 21 has an outline represented by the front-edge projected portion 21a that has
the front-edge recess portion 120a1 formed in a protruding shape that protrudes
upstream in the airflow. The front-edge recess portion 120a1 corresponds to the first
25 recess portion of the axial fan 100. In the front-edge projected portion 21a, the frontedge recess portion 120a1 forms an arc that protrudes upstream (toward Z1). In
other words, in the front-edge recess portion 120a1 of the front edge portion 21, the
pressure surface 25 forms an arc that recedes upstream (toward Z1). That is, in the
front-edge recess portion 120a1, the pressure surface 25 is formed in a recessed
30 shape that opens downstream (toward Z2). In the front-edge recess portion 120a1
24
of the front edge portion 21, the suction surface 26 forms an arc that protrudes
upstream (toward Z1). The front-edge projected portion 21a has the front-edge ridge
portion 121 that recedes downstream (toward Z2). In the front-edge projected
portion 21a, the front-edge recess portion 120a1 and the front-edge ridge portion 121
5 are formed in this order from the inner area toward the outer area in the radial
direction of the axial fan 100.
[0050]
A straight line in the meridian plane that connects the front-edge base portion
11a, which is the root joint of the front edge portion 21 with the hub 10, and the
10 maximum-point portion 121a is now defined as a straight line SL1. The front-edge
recess portion 120a1 is a portion of the front-edge projected portion 21a that is
located further upstream (toward Z1) than is the straight line SL1.
[0051]
As illustrated in Fig. 11, the front-edge recess portion 120a1 is formed further
15 inside than is the maximum-point portion 121a. A point on the front-edge recess
portion 120a1 located farthest from the first plane FHS is defined as the front edge
minimum-point portion Mn1. The front edge minimum-point portion Mn1 is located
further upstream (toward Z2) than is the maximum-point portion 121a. The front
edge minimum-point portion Mn1 is located most upstream (toward Z1) in the front20 edge recess portion 120a1.
[0052]
(Rear-Edge Recess Portion 120b1)
The rear edge portion 22 has the rear-edge recess portion 120b1. The rearedge recess portion 120b1 is formed in a recessed shape that recedes upstream in
25 the airflow. As illustrated in Fig. 11, the rear edge portion 22 has an outline
represented by the rear-edge projected portion 22e that has the rear-edge recess
portion 120b1 formed in a recessed shape that recedes upstream (toward Z1) in the
airflow. The rear-edge recess portion 120b1 corresponds to the second recess
portion of the axial fan 100. In the rear-edge projected portion 22e, the rear-edge
30 recess portion 120b1 forms an arc that recedes upstream (toward Z1). In other
25
words, in the rear-edge recess portion 120b1 of the rear edge portion 22, the
pressure surface 25 forms an arc that recedes upstream (toward Z1). That is, in the
rear-edge recess portion 120b1, the pressure surface 25 is formed in a recessed
shape that opens downstream (toward Z2). In the rear-edge recess portion 120b1 of
5 the rear edge portion 22, the suction surface 26 forms an arc that protrudes upstream
(toward Z1). The rear edge portion 22 further has the first ridge portion 122a, and
the second ridge portion 122b. The first ridge portion 122a and the second ridge
portion 122b are formed so as to protrude downstream (toward Z2). In the frontedge projected portion 21a, the first ridge portion 122a and the second ridge portion
10 122b each form an arc that protrudes downstream (toward Z2). The rear-edge
recess portion 120b1 is formed between the first ridge portion 122a and the second
ridge portion 122b. In the rear-edge projected portion 22e, the first ridge portion
122a, the rear-edge recess portion 120b1, and the second ridge portion 122b are
formed in this order from the inner area toward the outer area in the radial direction of
15 the axial fan 100.
[0053]
A straight line in the meridian plane that connects the rear-edge base portion
11b, which is the root joint of the rear edge portion 22 with the hub 10, and the
second maximum-point portion 123b is now defined as a straight line SL2. The rear20 edge recess portion 120b1 is a portion of the rear-edge projected portion 22e that is
located further upstream (toward Z1) than is the straight line SL2.
[0054]
As illustrated in Fig. 11, the rear-edge recess portion 120b1 is formed between
the first maximum-point portion 123a and the second maximum-point portion 123b.
25 A point on the rear-edge recess portion 120b1 located closest to the second plane
BHS is defined as the rear edge minimum-point portion Mn2. The rear edge
minimum-point portion Mn2 is located further upstream (toward Z1) than are the first
maximum-point portion 123a and the second maximum-point portion 123b. The rear
edge minimum-point portion Mn2 is located most upstream (toward Z1) in the rear30 edge recess portion 120b1.
26
[0055]
As illustrated in Fig. 11, the rear-edge recess portion 120b1 of the rear-edge
projected portion 22e is formed radially closer to the outer edge portion 23 than is the
front-edge recess portion 120a1 of the front-edge projected portion 21a. The front5 edge recess portion 120a1 of the front-edge projected portion 21a has a portion that
is formed closer to the inner edge portion 24 than is the rear-edge recess portion
120b1 of the rear-edge projected portion 22e.
[0056]
As with the axial fan 100, the axial fan 100A has the recessed passage 120
10 provided to the blade 20. The axial fan 100A has the front-edge recess portion
120a1 and the rear-edge recess portion 120b1 that are located at opposite ends of
the recessed passage 120 in the rotation direction DR.
[0057]
[Advantageous Effects of Axial Fan 100A]
15 In the axial fan 100A, the rear-edge recess portion 120b1 corresponding to the
second recess portion is formed further radially outside than is the front-edge recess
portion 120a1 corresponding to the first recess portion, and the front-edge recess
portion 120a1 has at least a portion that is formed further radially inside than is the
rear-edge recess portion 120b1. Consequently, the airflow along the pressure
20 surface 25 of the blade 20 is directed radially outward as the airflow proceeds from
the front-edge recess portion 120a1 of the front edge portion 21 toward the rear-edge
recess portion 120b1 of the rear edge portion 22. In this regard, generally speaking,
when an axial fan pushes out gas in the outer area of the blades, a greater moment is
imparted to the gas from the blades for the same rotation frequency of the axial fan
25 than a moment when the axial fan pushes out the gas in the inner area of the blades.
It is therefore desired for an axial fan to direct airflow toward and through the outer
area of the blades. The configuration of the axial fan 100A mentioned above allows
the airflow received at the front edge portion 21 of the blade 20 to easily flow, in the
direction of rotation of the blade 20, through the outer area of the pressure surface 25
30 where force is efficiently imparted from the blade 20 to the airflow. In this regard,
27
gas flowing along the pressure surface 25 of the blade 20 of the axial fan 100A can
obtain the energy of momentum due to movement of the gas from the inner area
toward the outer area in the radial direction. This leads to increased flow rate. As a
result, the axial fan 100A is able to efficiently send air, which leads to reduced power
5 consumption.
[0058]
Embodiment 3
Fig. 12 illustrates an exemplary shape of an axial fan 100B according to
Embodiment 3 that is rotated and projected onto a meridian plane. Parts identical in
10 configuration to those of the axial fan 100 or other axial fans illustrated in Figs. 1 to 11
are given the same reference signs and not described below in further detail. For
the axial fan 100B according to Embodiment 3, the configurations of the front-edge
recess portion 120a and the rear-edge recess portion 120b, as well as the
configurations of the front-edge recess portion 120a1 and the rear-edge recess
15 portion 120b1 are further specified.
[0059]
(Configuration of Axial Fan 100B)
As illustrated in Fig. 12, in the radial direction of the axial fan 100B, the rear
edge minimum-point portion Mn2 corresponding to the second minimum-point portion
20 is formed further outside than is the front edge minimum-point portion Mn1
corresponding to the first minimum-point portion. That is, in the direction
perpendicular to the rotating shaft RS, the distance between the rotating shaft RS and
the rear edge minimum-point portion Mn2 is greater than the distance between the
rotating shaft RS and the front edge minimum-point portion Mn1.
25 [0060]
A minimum-point portion 120m, which includes the front edge minimum-point
portion Mn1 and the rear edge minimum-point portion Mn2, is a portion of the
recessed passage 120 with the greatest elevation difference on the pressure surface
25 of the blade 20 in the axial direction of the rotating shaft RS. That is, the
30 minimum-point portion 120m is a portion of the recessed passage 120 where airflow
28
tends to concentrate. The minimum-point portion 120m is defined as the most
upstream portions of respective cross-sections of the recessed passage 120 in the
axial direction. The minimum-point portion 120m is also defined as a continuation,
between the front edge portion 21 and the rear edge portion 22, of the respective
5 most upstream portions of the cross-sections of the recessed passage 120 in the
axial direction.
[0061]
(Operational Effects of Axial Fan 100B)
In the axial fan 100B, the rear edge minimum-point portion Mn2 is located
10 further outside than is the front edge minimum-point portion Mn1 in the radial direction
of the axial fan 100B. This allows more airflow to be directed outward in the radial
direction of the axial fan 100B as the airflow proceeds from the front edge portion 21
toward the rear edge portion 22. When an airflow is directed from the inner area
toward the outer area in the radial direction as the airflow moves from the front edge
15 portion 21 to the rear edge portion 22, this makes it easier for a greater portion of the
airflow to obtain the energy of momentum due to movement of the airflow from the
inner area toward the outer area in the radial direction, in comparison to an airflow
that moves circumferentially along the pressure surface 25 of the axial fan 100. In
this regard, gas flowing along the pressure surface 25 of the blade 20 of the axial fan
20 100B can obtain the energy of momentum due to movement of the gas from the inner
area toward the outer area in the radial direction. This leads to increased flow rate.
As a result, the axial fan 100B is able to efficiently send air, which leads to reduced
power consumption.
[0062]
25 Embodiment 4
Fig. 13 illustrates an exemplary shape of an axial fan 100C according to
Embodiment 4 that is rotated and projected onto a meridian plane. Parts identical in
configuration to those of the axial fan 100 or other axial fans illustrated in Figs. 1 to 12
are given the same reference signs and not described below in further detail. For
30 the axial fan 100C according to Embodiment 4, the configurations of the front-edge
29
recess portion 120a and the rear-edge recess portion 120b, as well as the
configurations of the front-edge recess portion 120a1 and the rear-edge recess
portion 120b1 are further specified. Although the configurations of the front-edge
recess portion 120a and the rear-edge recess portion 120b are described below, the
5 configurations of the front-edge recess portion 120a1 and the rear-edge recess
portion 120b1 are identical to the configurations of the front-edge recess portion 120a
and the rear-edge recess portion 120b, and thus are not described below in further
detail.
[0063]
10 (Configuration of Axial Fan 100C)
As illustrated in Fig. 13, the rear-edge recess portion 120b corresponding to the
second recess portion of the blade 20 of the axial fan 100C has a radial width BW
less than the radial width FW of the front-edge recess portion 120a corresponding to
the first recess portion. The airflow passes through the blade 20 along the recessed
15 passage 120 as described below. In the front-edge projected portion 21a, the airflow
enters through the front-edge recess portion 120a centered at the front-edge-side
middle portion Aa and having a large radial width. Then, as the airflow moves
toward the rear edge portion 22, the airflow concentrates toward the rear-edge recess
portion 120b centered at the rear-edge-side middle portion Ab and having a small
20 radial width.
[0064]
(Operational Effects of Axial Fan 100C)
The axial fan 100C allows airflow to enter through a radially wide portion of the
blade 20, and then allows the incoming gas to concentrate so as to pass through the
25 outer area of the blade 20 where a large force is imparted from the blade 20 to the
airflow. Consequently, energy can be efficiently imparted to the airflow. This allows
the axial fan 100C to efficiently provide large airflow.
[0065]
Embodiment 5
30
Fig. 14 is a schematic perspective view of an axial fan 100D according to
Embodiment 5. Parts identical in configuration to those of the axial fan 100 or other
axial fans illustrated in Figs. 1 to 13 are given the same reference signs and not
described below in further detail. For the axial fan 100D according to Embodiment 5,
5 the configuration of the recessed passage 120 is further specified.
[0066]
(Configuration of Axial Fan 100D)
As described above, the minimum-point portion 120m is defined as the most
upstream portions of respective cross-sections of the recessed passage 120 in the
10 radial direction. The minimum-point portion 120m is also defined as a continuation,
between the front edge portion 21 and the rear edge portion 22, of the most upstream
portions of the cross-sections of the recessed passage 120 in the radial direction. In
the axial fan 100D according to Embodiment 5, the minimum-point portion 120m of
the recessed passage 120 is formed at a location that moves radially outward as the
15 minimum-point portion 120m extends from the front edge portion 21 to the rear edge
portion 22. In determining where to form the minimum-point portion 120m,
consideration is given to the balance between the flow rate of airflow suctioned from
the outer edge portion 23, and the external force of airflow passing into the recessed
passage 120 due to the centrifugal force exerted from the inner edge portion 24.
20 Accordingly, the minimum-point portion 120m may not necessarily be formed such
that its location moves monotonously from the inner area toward the outer area as the
minimum-point portion 120m extends from the front edge portion 21 toward the rear
edge portion 22.
[0067]
25 (Operational Effects of Axial Fan 100D)
The axial fan 100D allows airflow to pass through the blade 20 as described
below. The airflow enters through the front edge portion 21, and as the airflow
proceeds toward the rear edge portion 22, the airflow passes through the recessed
passage 120 along the minimum-point portion 120m. This allows the airflow to
30 concentrate so as to pass through the outer area of the blade 20 where a large force
31
is imparted from the blade 20 to the airflow. This allows the axial fan 100D to
efficiently impart energy to the airflow, and thus efficiently provide large airflow.
[0068]
Embodiment 6
5 Fig. 15 illustrates an exemplary shape of an axial fan 100E according to
Embodiment 6 that is rotated and projected onto a meridian plane. Parts identical in
configuration to those of the axial fan 100 or other axial fans illustrated in Figs. 1 to 14
are given the same reference signs and not described below in further detail. For
the axial fan 100C according to Embodiment 6, the configurations of the front-edge
10 recess portion 120a and the rear-edge recess portion 120b, as well as the
configurations of the front-edge recess portion 120a1 and the rear-edge recess
portion 120b1 are further specified. Although the configurations of the front-edge
recess portion 120a and the rear-edge recess portion 120b are described below, the
configurations of the front-edge recess portion 120a1 and the rear-edge recess
15 portion 120b1 are identical to the configurations of the front-edge recess portion 120a
and the rear-edge recess portion 120b, and thus are not described below in further
detail.
[0069]
(Configuration of Axial Fan 100E)
20 The recessed shape of the front-edge recess portion 120a has a depth in the
axial direction of the rotating shaft RS that is defined as a front edge height EH1. As
illustrated in Fig. 15, the front edge height EH1 is the distance between the front edge
minimum-point portion Mn1 and the maximum-point portion 121a in a direction
parallel to the axial direction of the rotating shaft RS. Likewise, the recessed shape
25 of the rear-edge recess portion 120b has a depth in the axial direction of the rotating
shaft RS that is defined as a rear edge height EH2. As illustrated in Fig. 15, the rear
edge height EH2 is the distance between the rear edge minimum-point portion Mn2
and the second maximum-point portion 123b in the direction parallel to the axial
direction of the rotating shaft RS. The front edge height EH1 and the rear edge
30 height EH2 respectively represent the depths of the recessed shapes of the front-
32
edge recess portion 120a and the rear-edge recess portion 120b. That is, the front
edge height EH1 and the rear edge height EH2 each represent a depth of the
corresponding recessed shape defined as the axial height of the recessed shape from
a reference point representing the most downstream wall (closest to Z2) located in
5 the outer area of the recessed shape, to a minimum point representing the most
upstream wall (closest to Z1) of the recessed shape.
[0070]
The axial fan 100E is formed such that the rear edge height EH2 of the rearedge recess portion 120b is greater than the front edge height EH1 of the front-edge
10 recess portion 120a. That is, in the axial fan 100E, the rear-edge recess portion
120b corresponding to the second recess portion has a depth greater than the depth
of the front-edge recess portion 120a corresponding to the first recess portion in the
axial direction of the rotating shaft RS.
[0071]
15 (Operational Effects of Axial Fan 100E)
Generally speaking, in an area near the rear end portion of an axial fan, the
pressure of airflow increases, and the airflow tends to leak outward due to centrifugal
force. The axial fan 100E is formed such that in an area near the rear edge portion
22 that is subject to increased airflow pressure and the influence of centrifugal force,
20 the rear edge height EH2 of the rear-edge recess portion 120b is greater than the
front edge height EH1 of the front-edge recess portion 120a. The configuration of
the axial fan 100E mentioned above helps to ensure that in an area near the rear
edge portion 22 that is subject to increased airflow pressure and the influence of
centrifugal force, leakage of airflow toward the outer area of the blade 20 is reduced.
25 This makes it possible to reliably direct the airflow through the recessed passage 120.
[0072]
Embodiment 7
Fig. 16 illustrates an exemplary shape of an axial fan 100F according to
Embodiment 7 that is rotated and projected onto a meridian plane. Parts identical in
30 configuration to those of the axial fan 100 or other axial fans illustrated in Figs. 1 to 15
33
are given the same reference signs and not described below in further detail. For
the axial fan 100F according to Embodiment 7, the configuration of the blade 20 is
further specified. Although the configuration of the rear-edge recess portion 120b is
described below, the configuration of the rear-edge recess portion 120b1 is identical
5 to the configurations of the rear-edge recess portion 120b, and thus is not described
below in further detail.
[0073]
(Rear Edge Portion 22)
In the meridian plane MP onto which the rear edge portion 22 is rotated and
10 projected, the rear-edge projected portion 22e is formed by a curve including Sshaped portions. The rear-edge projected portion 22e has the first S-shaped portion
22a, the second S-shaped portion 22b, and a third S-shaped portion 22c. The first
S-shaped portion 22a, the second S-shaped portion 22b, and the third S-shaped
portion 22c of the rear-edge projected portion 22e are each formed by an S-shaped
15 curve that arcs upstream and downstream in the airflow. The rear-edge projected
portion 22e is formed by a curve including a combination of the first S-shaped portion
22a, the second S-shaped portion 22b, and the third S-shaped portion 22c located
between the first S-shaped portion 22a and the second S-shaped portion 22b.
[0074]
20 The rear-edge projected portion 22e has the rear edge first-inflection-point
portion Se1, which is a point of inflection of the first S-shaped portion 22a, the rear
edge second-inflection-point portion Se2, which is a point of inflection of the second
S-shaped portion 22b, and a rear edge third-inflection-point portion Se3, which is a
point of inflection of the third S-shaped portion 22c. In the direction perpendicular to
25 the rotating shaft RS, that is, in the radial direction of the axial fan 100, the rear edge
first-inflection-point portion Se1 is formed further inside than is the rear edge secondinflection-point portion Se2. In the direction perpendicular to the rotating shaft RS,
that is, in the radial direction of the axial fan 100, the rear edge third-inflection-point
portion Se3 is formed between the rear edge first-inflection-point portion Se1 and the
30 rear edge second-inflection-point portion Se2.
34
[0075]
(Rear-Edge Recess Portion 120b)
The rear-edge projected portion 22e has, between the rear edge first-inflectionpoint portion Se1 and the rear edge second-inflection-point portion Se2, the rear-edge
5 recess portion 120b formed in a recessed shape that recedes upstream (toward Z1).
The rear-edge recess portion 120b has a rear-edge inner recess portion 120ba, which
is formed in a recessed shape receding upstream in the airflow, and a rear-edge outer
recess portion 120bb, which is formed in a recessed shape receding upstream in the
airflow. The rear-edge inner recess portion 120ba corresponds to a third recess
10 portion of the axial fan 100, and the rear-edge outer recess portion 120bb
corresponds to a fourth recess portion of the axial fan 100. The rear-edge inner
recess portion 120ba is formed further inside of the blade 20 than is the rear-edge
outer recess portion 120bb, and the rear-edge outer recess portion 120bb is formed
further outside of the blade 20 than is the rear-edge inner recess portion 120ba. The
15 rear-edge inner recess portion 120ba and the rear-edge outer recess portion 120bb
each form an arc that recedes upstream (toward Z1) in the rear-edge projected
portion 22e. The rear-edge inner recess portion 120ba and the rear-edge outer
recess portion 120bb are formed so as to extend from a central part of the blade 20 to
the rear-edge projected portion 22e in a direction opposite to the rotation direction DR
20 of the axial fan 100F.
[0076]
The rear-edge projected portion 22e has the first ridge portion 122a that forms
an arc protruding downstream (toward Z2). The rear-edge projected portion 22e has
the second ridge portion 122b that forms an arc protruding downstream (toward Z2).
25 Further, the rear-edge recess portion 120b of the rear-edge projected portion 22e has
a third ridge portion 122c that forms an arc protruding downstream (toward Z2). The
rear-edge recess portion 120b is formed between the first ridge portion 122a and the
second ridge portion 122b. The rear-edge inner recess portion 120ba is formed
between the first ridge portion 122a and the third ridge portion 122c. The rear-edge
30 outer recess portion 120bb is formed between the third ridge portion 122c and the
35
second ridge portion 122b. In the rear-edge projected portion 22e, the first ridge
portion 122a, the rear-edge recess portion 120b, and the second ridge portion 122b
are formed in this order from the inner area toward the outer area in the radial
direction of the axial fan 100. In the rear-edge recess portion 120b, the rear-edge
5 inner recess portion 120ba, the third ridge portion 122c, and the rear-edge outer
recess portion 120bb are formed. Accordingly, in the rear-edge projected portion
22e, the first ridge portion 122a, the rear-edge inner recess portion 120ba, the third
ridge portion 122c, the rear-edge outer recess portion 120bb, and the second ridge
portion 122b are formed in this order from the inner area toward the outer area in the
10 radial direction of the axial fan 100.
[0077]
The axial fan 100F has the rear edge third-inflection-point portion Se3 located
between the rear edge first-inflection-point portion Se1 and the rear edge secondinflection-point portion Se2 of the rear-edge projected portion 22e that define the
15 recessed passage 120. The axial fan 100F has the third ridge portion 122c provided
in the rear-edge recess portion 120b. Due to the configuration of the axial fan 100F
mentioned above, the recessed passage 120 is formed such that from a central part
of the blade 20 to the rear-edge projected portion 22e in the circumferential direction
of the axial fan 100F, the recessed passage 120 splits into two passages, one leading
20 toward the rear-edge inner recess portion 120ba and the other leading toward the
rear-edge outer recess portion 120bb. That is, due to the configuration of the axial
fan 100F mentioned above, the recessed passage 120 is formed such that from a
central part of the blade 20 to the rear-edge projected portion 22e in the
circumferential direction of the axial fan 100F, the recessed passage 120 splits into
25 multiple parts.
[0078]
Due to the presence of the rear-edge inner recess portion 120ba and the rearedge outer recess portion 120bb, the axial fan 100F has longitudinal grooves on the
pressure surface 25 of the blade 20 that extend in the direction of flow of air. The
30 axial fan 100F thus has features shaped like commonly called riblets on the pressure
36
surface 25 of the blade 20. As illustrated in Fig. 16, in a part of the blade 20 near the
rear edge portion 22, the airflow entering through the front edge portion 21 splits into
two flows that pass along the recessed passage 120.
[0079]
5 (Operational Effects of Axial Fan 100F)
Fig. 17 is a perspective view of an axial fan 100G according to a comparative
example, illustrating how airflow blows from the axial fan 100G. The axial fan 100G
according to the comparative example corresponds in configuration to each of the
axial fans 100 to 100E according to Embodiments 1 to 6. In the axial fan 100G, the
10 airflow passing through a part of the recessed passage 120 near the rear edge
portion 22 concentrates toward the outer area of the recessed passage 120 as
illustrated in Fig. 17. The resulting wind speed distribution WSD is formed such that
the outgoing flow has an increased wind speed in the outer area of the recessed
passage 120. Therefore, in the rear edge portion 22 of the axial fan 100G, the
15 resulting difference in wind speed may cause vortices VT to develop in some cases.
The vortices VT generated in the rear edge portion 22 can cause axial energy loss,
and can also cause increased noise generation.
[0080]
Fig. 18 is a perspective view of an axial fan 100F according to Embodiment 7,
20 illustrating how airflow blows from the axial fan 100F. As illustrated in Fig. 18, in
contrast to the axial fan 100G according to the comparative example, the axial fan
100F according to Embodiment 7 causes airflow to pass along the recessed passage
120 that is subdivided into multiple parts near the rear edge portion 22. The rearedge recess portion 120b of the axial fan 100F has the rear-edge inner recess portion
25 120ba, which corresponds to the third recess portion formed in a recessed shape
receding upstream in the airflow, and the rear-edge outer recess portion 120bb, which
corresponds to the fourth recess portion formed in a recessed shape receding
upstream in the airflow. Due to the configuration of the axial fan 100F mentioned
above, in a portion of the recessed passage 120 near the rear edge portion 22,
30 airflow that tends to concentrate locally is streamlined by the finely subdivided
37
portions of the recessed passage 120. This helps to ensure that the outgoing airflow
from the blade 20 does not concentrate in a narrow area. This leads to uniform
airflow velocity. Consequently, as illustrated in Fig. 18, the axial fan 100F allows for
uniform wind speed distribution WSD of the outgoing flow from the inner area to the
5 outer area of the recessed passage 120. As a result, the axial fan 100F allows for
reduced generation of vortices VT near the rear edge portion 22, reduced energy loss
caused by such generation of the vortices VT, and further, reduced noise generation
caused by the vortices VT. That is, the above-mentioned configuration of the axial
fan 100F helps to reduce energy loss resulting from a difference in velocity that
10 develops as a high velocity flow and a low velocity flow mix together after exiting the
axial fan 100F.
[0081]
Embodiment 8
Fig. 19 is a schematic perspective view of an axial fan 100H according to
15 Embodiment 8. Parts identical in configuration to those of the axial fan 100 or other
axial fans illustrated in Figs. 1 to 18 are given the same reference signs and not
described below in further detail. For the axial fan 100H according to Embodiment 8,
the configuration of the rear edge portion 22 of the blade 20 is further specified. The
shape of the axial fan 100H according to Embodiment 8 rotated and projected on the
20 meridian plane MP illustrated in Fig. 1 is identical to the shape of the axial fan 100
illustrated in Fig. 2.
[0082]
(Configuration of Axial Fan 100H)
In plan view parallel to the rotating shaft RS, the rear edge portion 22 has a
25 portion defining the rear-edge recess portion 120b and having an edge, and the edge
has a notched portion 27 formed by notching the edge toward the front edge portion
21. The rear edge portion 22 of the blade 20 has at least one such notched portion
27. The notched portion 27 corresponds to where the rear edge portion 22 defining
the blade 20 has the shape of a notch that is notched in the circumferential direction
30 of the axial fan 100H. That is, the notched portion 27 is a portion of the rear edge
38
portion 22 that has the shape of a notch that is notched from the rear edge portion 22
toward the front edge portion 21. The blade 20 is formed such that its edge defining
the notched portion 27 has a radial width that decreases toward the front edge portion
21. In the notched portion 27, the rear edge portion 22 defines an edge that recedes
5 toward the front edge portion 21. The notched portion 27 opens in a direction
opposite to the rotation direction DR. In plan view parallel to the axial direction of the
rotating shaft RS, an edge of the rear edge portion 22 that defines the notched portion
27 is formed in, for example, a U-shape or a V-shape.
[0083]
10 The notched portion 27 is formed between the rear edge first-inflection-point
portion Se1 and the rear edge second-inflection-point portion Se2. That is, the
notched portion 27 is formed in the rear-edge recess portion 120b of the rear edge
portion 22. Therefore, the rear-edge recess portion 120b forms an arc that recedes
upstream (toward Z1), and defines an edge that recedes toward the front edge
15 portion 21 due to the presence of the notched portion 27.
[0084]
(Operational Effects of Axial Fan 100H)
The axial fan 100F according to Embodiment 7 described above allows the
wind speed distribution WSD of the outgoing flow to be made uniform from the inner
20 area to the outer area of the recessed passage 120. However, the above-mentioned
approach, that is, adding irregularities to the recessed passage 120 to achieve
uniform outgoing wind speed as with the axial fan 100F according to Embodiment 7,
has a potential problem in that depending on the radial width, it may be difficult to
provide the irregularities on the pressure surface 25 with an elevation difference.
25 [0085]
In the axial fan 100H according to Embodiment 8, the presence of the notched
portion 27 in the rear-edge recess portion 120b makes it possible to adjust the chord
length WL depicted in Fig. 6. This configuration of the axial fan 100H helps to
reduce the force with which the blade 20 pushes airflow in the recessed passage 120.
30 This further facilitates creation of an outgoing wind speed distribution aimed to
39
achieve uniform outgoing wind speed. Further, the above-mentioned configuration
of the axial fan 100H results in reduced wind speed difference between the outer and
inner areas of the recessed passage 120. This helps to reduce energy loss resulting
from a difference in velocity that develops as a high velocity flow and a low velocity
5 flow mix together after exiting the axial fan 100H.
[0086]
Embodiment 9
Fig. 20 is a schematic perspective view of an axial fan 100I according to
Embodiment 9. Parts identical in configuration to those of the axial fan 100 or other
10 axial fans illustrated in Figs. 1 to 19 are given the same reference signs and not
described below in further detail. For the axial fan 100I according to Embodiment 9,
the configuration of the front edge portion 21 of the blade 20, and the configuration of
the rear edge portion 22 of the blade 20 are further specified.
[0087]
15 (Configuration of Axial Fan 100I)
The front edge portion 21 has a portion defining the front-edge recess portion
120a and having an edge, and the edge has a corrugated serration 28. Alternatively,
the rear edge portion 22 has a portion defining the rear-edge recess portion 120b and
having an edge, and the edge has the corrugated serration 28. The front edge
20 portion 21 and the rear edge portion 22 of the blade 20 are provided with at least one
serration 28. The serration 28 may be provided only in the front edge portion 21, or
may be provided only in the rear edge portion 22. Alternatively, the serration 28 may
be provided in both the front edge portion 21 and the rear edge portion 22. In plan
view parallel to the axial direction of the rotating shaft RS, the serration 28 is a
25 grooved portion in the shape of saw teeth or fine corrugations formed at an edge of
the front edge portion 21 or the rear edge portion 22. The grooves defining the
serration 28 are formed in an edge portion of the blade 20 so as to extend between
an area upstream (near Z1) in the airflow and an area downstream (near Z2) in the
airflow.
30 [0088]
40
The serration 28 is formed in the rear edge portion 22 between the rear edge
first-inflection-point portion Se1 and the rear edge second-inflection-point portion Se2.
That is, the serration 28 is formed in the rear-edge recess portion 120b of the rear
edge portion 22. The serration 28 is formed in the front edge portion 21 between the
5 front-edge base portion 11a and the front edge inflection-point portion Sf1. That is,
the serration 28 is formed in the front-edge recess portion 120a of the front edge
portion 21.
[0089]
(Operational Effects of Axial Fan 100I)
10 The presence of the serration 28 in the front-edge recess portion 120a helps to
ensure that if the direction of airflow and the direction of the leading edge of the blade
20 are greatly misaligned due to external disturbances, the airflow at the leading edge
of the blade 20 can be disturbed by the serration 28 to thereby make the direction of
airflow less clearly defined. As a result, the axial fan 100I with the serration 28
15 provided in the front-edge recess portion 120a allows airflow to be easily directed into
the front-edge recess portion 120a, in comparison to an axial fan with no such
serration 28 provided in the front-edge recess portion 120a.
[0090]
The serration 28 provided to the rear-edge recess portion 120b makes it
20 possible to disturb airflow that concentrates locally in the rear-edge recess portion
120b to thereby eliminate areas of extremely high outgoing wind speed. As a result,
the axial fan 100I allows for reduced generation of vortices VT near the rear edge
portion 22, reduced energy loss caused by such generation of the vortices VT, and
further, reduced noise generation caused by the vortices VT.
25 [0091]
Embodiment 10
Embodiment 10 is directed to using the axial fan 100 or other axial fans
according to Embodiments 1 to 9 for an outdoor unit 50, which is used as an airsending device of a refrigeration cycle apparatus 70.
30 [0092]
41
Fig. 21 is a schematic diagram of the refrigeration cycle apparatus 70
according to Embodiment 10. Although the following description is directed to the
refrigeration cycle apparatus 70 used for air-conditioning purposes, this is not
intended to limit the use of the refrigeration cycle apparatus 70 to air conditioning.
5 For example, the refrigeration cycle apparatus 70 is used for refrigeration or airconditioning purposes, such as for refrigerators, freezers, vending machines, airconditioning apparatuses, refrigeration apparatuses, and water heaters.
[0093]
As illustrated in Fig. 21, the refrigeration cycle apparatus 70 includes a
10 refrigerant circuit 71 formed by sequentially connecting a compressor 64, a
condenser 72, an expansion valve 74, and an evaporator 73 by a refrigerant pipe. A
condenser fan 72a, which sends air used for heat exchange to the condenser 72, is
provided to the condenser 72. An evaporator fan 73a, which sends air used for heat
exchange to the evaporator 73, is provided to the evaporator 73. At least one of the
15 condenser fan 72a and the evaporator fan 73a is the axial fan 100 according to any
one of Embodiments 1 to 9 mentioned above. The refrigeration cycle apparatus 70
may be configured to switch between heating operation and cooling operation, by
providing the refrigerant circuit 71 with a flow switching device such as a four-way
valve that switches the flows of refrigerant.
20 [0094]
Fig. 22 is a perspective view, as seen from an air outlet, of the outdoor unit 50
used as an air-sending device. Fig. 23 is a top view of the outdoor unit 50 for
explaining the configuration of the outdoor unit 50. Fig. 24 illustrates the outdoor unit
50 with a fan grille removed from the outdoor unit 50. Fig. 25 illustrates the internal
25 configuration of the outdoor unit 50 with the fan grille, a front panel, and other
components removed from the outdoor unit 50.
[0095]
As illustrated in Figs. 22 to 25, an outdoor unit body 51 used as a casing is
formed as an enclosure having the following surfaces: a lateral surface 51a and a
30 lateral surface 51c, which define a pair of left and right lateral surfaces; a front surface
42
51b; a back surface 51d; a top surface 51e; and a bottom surface 51f. The lateral
surface 51a and the back surface 51d each have an opening for suctioning air from
outside. The front surface 51b has an air outlet 53 formed in a front panel 52 to blow
air outside. Further, the air outlet 53 is covered with a fan grille 54 to ensure safety
5 by preventing contact between the axial fan 100 and, for example, an object located
outside the outdoor unit body 51. Arrows AR in Fig. 23 represent the flow of air.
[0096]
The axial fan 100 and a fan motor 61 are accommodated in the outdoor unit
body 51. The axial fan 100 is connected via a rotating shaft 62 to the fan motor 61,
10 which is a drive source located near the back surface 51d. The axial fan 100 is
driven to rotate by the fan motor 61. The fan motor 61 provides a drive force to the
axial fan 100.
[0097]
The interior of the outdoor unit body 51 is divided by a partition plate 51g,
15 which is a wall element, into an air-sending chamber 56 in which the axial fan 100 is
installed, and a machine chamber 57 in which the compressor 64 and other
components are installed. A heat exchanger 68, which extends in a substantially Lshape in plan view, is disposed in the air-sending chamber 56 near the lateral surface
51a and the back surface 51d. The heat exchanger 68 is used as the condenser 72
20 during heating operation, and is used as the evaporator 73 during cooling operation.
[0098]
A bellmouth 63 is disposed radially outward of the axial fan 100 disposed in the
air-sending chamber 56. The bellmouth 63 is located further outside than is the
outer end of the blades 20, and defines an annular shape in the direction of rotation of
25 the axial fan 100. The partition plate 51g is located beside one side of the bellmouth
63, and a portion of the heat exchanger 68 is located beside the other side of the
bellmouth 63.
[0099]
The front end of the bellmouth 63 is connected to the front panel 52 of the
30 outdoor unit 50 so as to surround the periphery of the air outlet 53. The bellmouth
43
63 may be integral with the front panel 52, or may be provided as a separate
component that can be connected to the front panel 52. Due to the presence of the
bellmouth 63, the passage between the inlet side and the outlet side of the bellmouth
63 is defined as an air passageway near the air outlet 53. That is, the air
5 passageway near the air outlet 53 is partitioned off by the bellmouth 63 from other
spaces in the air-sending chamber 56.
[0100]
The heat exchanger 68 disposed near the air inlet of the axial fan 100 includes
fins with plate-like surfaces arranged side by side in parallel to each other, and heat
10 transfer tubes penetrating the fins in a direction in which the fins are arranged side by
side. Refrigerant that circulates in the refrigerant circuit flows in the heat transfer
tubes. In the heat exchanger 68 according to Embodiment 10, rows of heat transfer
tubes extend in an L-shape over the lateral surface 51a and the back surface 51d of
the outdoor unit body 51, and follow a meandering path while penetrating the fins.
15 The heat exchanger 68 is connected to the compressor 64 via a pipe 65 or other
components, and is further connected to an indoor-side heat exchanger (not
illustrated), the expansion valve, and other components to form the refrigerant circuit
71 of the air-conditioning apparatus. A board case 66 is disposed in the machine
chamber 57. A control board 67 disposed in the board case 66 controls devices
20 mounted in the outdoor unit.
[0101]
(Operation Effects of Refrigeration Cycle Apparatus 70)
Embodiment 10 can provide advantages similar to Embodiments 1 to 9
corresponding to Embodiment 10. For example, as described above, the axial fans
25 100 to 100I allow the airflow received at the front edge portion 21 of each blade 20 to
easily flow, in the rotation direction DR of the blade 20, through the outer area of the
pressure surface 25 where force is efficiently imparted from the blade 20 to the
airflow. Mounting one or more of the axial fans 100 to 100I to an air-sending device
makes it possible for the air-sending device to efficiently send air at increased flow
30 rate. By mounting one or more of the axial fans 100 to 100I to an air-conditioning
44
apparatus or water-heating outdoor unit that is used as the refrigeration cycle
apparatus 70 including components such as the compressor 64 and a heat
exchanger, an increase in flow rate of airflow through the heat exchanger can be
gained with low noise and high efficiency, which leads to reduced noise and improved
5 energy saving for the apparatus.
[0102]
The configurations described in the foregoing description of the embodiments
are intended to be illustrative only. These configurations can be combined with other
known techniques, or can be partially omitted or changed without departing from the
10 scope of the disclosure.
Reference Signs List
[0103]
10: hub, 10a: hub projected portion, 11: base portion, 11a: front-edge base
portion, 11b: rear-edge base portion, 20: blade, 20a: blade projected portion, 21: front
15 edge portion, 21a: front-edge projected portion, 22: rear edge portion, 22a: first Sshaped portion, 22b: second S-shaped portion, 22c: third S-shaped portion, 22e: rearedge projected portion, 23: outer edge portion, 24: inner edge portion, 25: pressure
surface, 26: suction surface, 27: notched portion, 28: serration, 50: outdoor unit, 51:
outdoor unit body, 51a: lateral surface, 51b: front surface, 51c: lateral surface, 51d:
20 back surface, 51e: top surface, 51f: bottom surface, 51g: partition plate, 52: front
panel, 53: air outlet, 54: fan grille, 56: air-sending chamber, 57: machine chamber, 61:
fan motor, 62: rotating shaft, 63: bellmouth, 64: compressor, 65: pipe, 66: board case,
67: control board, 68: heat exchanger, 70: refrigeration cycle apparatus, 71:
refrigerant circuit, 72: condenser, 72a: condenser fan, 73: evaporator, 73a: evaporator
25 fan, 74: expansion valve, 100: axial fan, 100A: axial fan, 100B: axial fan, 100C: axial
fan, 100D: axial fan, 100E: axial fan, 100F: axial fan, 100G: axial fan, 100H: axial fan,
100I: axial fan, 120: recessed passage, 120a: front-edge recess portion, 120a1: frontedge recess portion, 120b: rear-edge recess portion, 120b1: rear-edge recess
portion, 120ba: rear-edge inner recess portion, 120bb: rear-edge outer recess portion,
30 120m: minimum-point portion, 121: front-edge ridge portion, 121a: maximum-point
45
portion, 122a: first ridge portion, 122b: second ridge portion, 122c: third ridge portion,
123a: first maximum-point portion, 123b: second maximum-point portion

46
We Claim :
[Claim 1]
An axial fan, comprising:
a hub having a rotating shaft and configured to be driven to rotate; and
5 blades provided to the hub, the blades each having a front edge portion and a
rear edge portion,
in a state in which the blades rotate to generate an airflow, the front edge
portion being placed most upstream in the airflow, and the rear edge portion being
placed most downstream in the airflow,
10 in a shape of the blades rotated and projected onto a meridian plane that
covers shapes of the blades and a shape of the rotating shaft,
the front edge portion having an outline represented by a front-edge projected
portion having a first recess portion formed in a recessed shape that recedes
upstream in the airflow,
15 the rear edge portion having an outline represented by a rear-edge projected
portion having a second recess portion formed in a recessed shape that recedes
upstream in the airflow,
the first recess portion having at least a portion that is formed further radially
inside than is the second recess portion.
20 [Claim 2]
The axial fan of claim 1,
wherein the front-edge projected portion has a front edge inflection-point
portion used as a point of inflection, the front-edge projected portion being formed by
an S-shaped curve that arcs upstream and downstream in the airflow,
25 wherein the first recess portion is formed between a base portion of the front
edge portion and the front edge inflection-point portion, the base portion being a root
joint of the front edge portion with the hub,
wherein the rear-edge projected portion has
47
a first S-shaped portion having a first inflection-point portion used as a point of
inflection, the first S-shaped portion being formed by an S-shaped curve that arcs
upstream and downstream in the airflow, and
a second S-shaped portion having a second inflection-point portion used as a
5 point of inflection, the second S-shaped portion being formed by an S-shaped curve
that arcs upstream and downstream in the airflow, and
wherein the second recess portion is formed between the first inflection-point
portion and the second inflection-point portion.
[Claim 3]
10 The axial fan of claim 2, wherein the front edge inflection-point portion is
located radially between the first inflection-point portion and the second inflectionpoint portion.
[Claim 4]
The axial fan of claim 2 or 3,
15 wherein the rear-edge projected portion further has a third S-shaped portion
disposed between the first S-shaped portion and the second S-shaped portion, the
third S-shaped portion having a third inflection-point portion used as a point of
inflection, the third S-shaped portion being formed by an S-shaped curve that arcs
upstream and downstream in the airflow, and
20 wherein the second recess portion has
a third recess portion formed in a recessed shape that recedes upstream in the
airflow, and
a fourth recess portion formed in a recessed shape that recedes upstream in
the airflow.
25 [Claim 5]
The axial fan of any one of claims 1 to 4, wherein the second recess portion is
formed further radially outside than is the first recess portion.
[Claim 6]
The axial fan of any one of claims 1 to 5,
48
wherein the first recess portion of the front-edge projected portion has a first
minimum-point portion, the first minimum-point portion being located most upstream
in the airflow,
wherein the second recess portion of the rear-edge projected portion has a
5 second minimum-point portion, the second minimum-point portion being located most
upstream in the airflow, and
wherein the second minimum-point portion is formed further radially outside
than is the first minimum-point portion.
[Claim 7]
10 The axial fan of any one of claims 1 to 6, wherein the second recess portion
has a width less than a width of the first recess portion in a radial direction.
[Claim 8]
The axial fan of any one of claims 1 to 7, wherein the front-edge projected
portion has, in a radial direction, a proportion of the first recess portion greater than a
15 proportion of a portion formed in a recessed shape that recedes downstream in the
airflow.
[Claim 9]
The axial fan of any one of claims 1 to 8, wherein in plan view parallel to the
rotating shaft, the rear edge portion has a portion defining the second recess portion
20 and having an edge, the rear edge portion having a notched portion formed by
notching the edge toward the front edge portion.
[Claim 10]
The axial fan of any one of claims 1 to 9, wherein the front edge portion has a
portion defining the first recess portion and having an edge, the edge having a
25 corrugated serration.
[Claim 11]
The axial fan of any one of claims 1 to 10, wherein the rear edge portion has a
portion defining the second recess portion and having an edge, the edge having a
corrugated serration.
30 [Claim 12]
49
The axial fan of any one of claims 1 to 11, wherein the second recess portion
has a depth greater than a depth of the first recess portion in an axial direction of the
rotating shaft.
[Claim 13]
5 The axial fan of any one of claims 1 to 12,
wherein the blades each have a pressure surface defining a surface that faces
downstream in the airflow,
wherein the pressure surface has a recessed passage formed in a recessed
shape that recedes upstream in the airflow,
10 wherein the recessed passage is formed between the front edge portion and
the rear edge portion, and
wherein in a circumferential direction, the recessed passage has an end portion
near the front edge portion that is defined by a portion of the recessed passage that
defines the first recess portion, and the recessed passage has an end portion near
15 the rear edge portion that is defined by a portion of the recessed passage that defines
the second recess portion.
[Claim 14]
The axial fan of claim 13, wherein the recessed passage has a minimum-point
portion, the minimum-point portion defining a most upstream portion of a cross20 section of the recessed passage in a radial direction and extending continuously
between the front edge portion and the rear edge portion, the minimum-point portion
being directed radially outward as the minimum-point portion extends from the front
edge portion to the rear edge portion.
[Claim 15]
25 An air-sending device, comprising:
the axial fan of any one of claims 1 to 14;
a drive source configured to provide a drive force to the axial fan; and
a casing that accommodates the axial fan and the drive source.
[Claim 16]
30 A refrigeration cycle apparatus, comprising:
50
the air-sending device of claim 15; and
a refrigerant circuit having a condenser and an evaporator,
the air-sending device being configured to send air to at least one of the
condenser and the evaporator.