BACKGROUND OF THE INVENTION
1. Technical Field
[0001] The present invention relates to a crossflow fan used in an air conditioner or the
like.
2. Related Art
[0002] In a crossflow fan that is used in an air conditioner, an air curtain or the like,
a distance between a fan rotor (impeller) and a tongue is preferably shortened to
improve efficiency thereof, the tongue provided at a predetermined height along the
outer diameter of the fan rotor. In this case, however, when a blade of the fan rotor
moves from a tongue region to an air suction region, the flow of air around the blade
rapidly varies, thereby increasing noise in a termination region of the tongue region.
[0003] Therefore, in the conventional crossflow fan, in order to prevent the flow around
the blade from rapidly varying when the blade of the fan rotor moves from the tongue
region to the air suction region, a comb-shaped groove portion is provided at the
upper end of the tongue. As the comb-shaped groove portion approaches the air suction
region from the tongue region, the width thereof is enlarged, and the depth thereof
is changed between the right and left rotors of the fan rotor (for example, refer
to
Japanese Patent No. 3 248 466 (pages 2 and 3, and Fig. 3)).
JP 4-080 533 A discloses an exemplary crossflow fan comprising a stabiliser having recess and projection
parts for dispersing the frequency of a vane pitch sound generated by the cross-flow
fan.
SUMMARY
[0004] In such a crossflow fan, however, since the length of the tongue in a direction along
the outer diameter of the fan rotor (impeller) is shortened, a leakage flow rate flowing
from a discharge side to a suction side becomes large. Therefore, a pressure difference
between the suction side and the discharge side becomes small, and an unstable circular
vortex occurs in the crossflow fan. Accordingly, when a flow rate is low or dust is
accumulated in a filter, a flow reverse to an original outlet flow is likely to occur.
Consequently, efficiency is degraded, and noise increases.
[0005] According to an aspect of the invention, there is provided a crossflow fan in which
the efficiency is high while reducing noise.
[0006] The present invention provides a crossflow fan according to independent claim 1.
Further embodiments of the invention may be realised in accordance with the dependent
claims.
[0007] According to the above-aspects, it is possible to provide a crossflow fan in which
the efficiency is high while reducing noise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008]
- Fig. 1
- is a sectional view of an air conditioner using a crossflow fan according to a first
non claimed example.
- Figs. 2A, 2B
- are sectional views of a nose of the crossflow fan according to the first non claimed
example.
- Fig. 3
- is a perspective view of the nose of the crossflow fan according to the first non
claimed example.
- Figs. 4A, 4B
- are sectional views of the nose of the crossflow fan according to the first non claimed
example.
- Fig. 5
- is a sectional view of a nose of a crossflow fan according to a second non claimed
example.
- Fig. 6
- is a perspective view of the nose of the crossflow fan according to the second non
claimed example.
- Fig. 7
- is a perspective view of the nose of the crossflow fan according to the second non
claimed example.
- Fig. 8
- is a perspective view of a nose of a crossflow fan according to a third non claimed
example.
- Fig. 9
- is a perspective view of a nose of a crossflow fan according to a fourth non claimed
example
- Fig. 10
- is a sectional view of the nose of the crossflow fan according to the invention.
- Fig. 11
- is a perspective view of the nose of the crossflow fan according to the invention.
- Figs. 12A, 12B
- are sectional views of the nose of the crossflow fan according to the invention.
- Figs. 13A, 13B
- are sectional views of the nose of the crossflow fan according to the invention.
DESCRIPTION OF THE EMBODIMENTS
First Example
[0009] Fig. 1 is a sectional view illustrating an air conditioner using a crossflow fan
according to a first example. In the accompanying drawings, the same reference numeral
represents the same component or a component corresponding thereto, which is common
in the overall specification. The shapes of components represented in the overall
specification are only examples, and are not limited thereto.
[0010] In Fig. 1, a front-side suction grille 2 is provided on the front surface of a housing
1 of the air conditioner, and an upper-side suction grille 3 is provided on the upper
surface thereof. Inside the housing 1, a filter 4 for removing dust contained in the
air is provided along
the front-side suction grille 2 and the upper-side suction grille 3. A heat exchanger
5, which exchangers heat with the air sucked from the front-side suction grille 2
and the upper-side suction grille 3, is disposed along the filter 4. At a lower portion
of the front surface of the housing 1, a nose 6 is installed so as to be connected
to the front-side suction grille 2. On the inner rear surface of the housing 1, a
guider 7 is installed, which introduces the flow of air within the air conditioner.
[0011] Between the heat exchanger 5 and the guider 7, an impeller 12 is disposed which rotates
around a rotating shaft 13 of the crossflow fan. The impeller 12 is composed of the
rotating shaft 13, a plurality of discshaped side plates 14 fixed to both ends and
the middle of the rotating shaft 13, and impeller blades 15 radially fixed to the
outer circumferences of the side plates 14. The crossflow fan is provided with the
impeller 12, the guider 7, and the nose 6.
[0012] In the lower portion of the housing 1, an air outlet 8 is provided between the nose
6 and the guider 7, through which air is blown outside the air conditioner. In the
vicinity of the air outlet 8, a left-to-right wind direction changing plate 9 connected
to the nose 6 is provided which changes the flow of air in a direction of the rotating
shaft 13, and similarly, in the vicinity of the outlet 8, an up-and-down wind direction
changing plate 10 is provided which changes the flow of air in the up and down direction.
Further, inside the rear surface of the housing 1, that is, at the back surface side
of the guider 7, piping 11 is disposed in which a refrigerant of the heat exchanger
5 flows.
[0013] As the impeller 12 rotates in a direction of an arrow C of Fig. 1, air is sucked
from suction sides of the front-side suction grille 2 and the upper-side suction grille
3. The sucked air is heat-exchanged by the heat exchanger 5 through the filter 4,
and then flows through the impeller blade 15 or the impeller 12. After the air flows
through the impeller blade 15 of the impeller 12, the wind direction thereof is properly
adjusted by the left-and-right wind direction changing plate 9 and the up-and-down
wind direction changing plate 10. Then, the air is blown out of the air outlet 8.
[0014] Fig. 2 is a sectional view illustrating the nose of the crossflow fan according to
the first example, and Fig. 3 is a perspective view of the nose of the crossflow fan
according to the first example. Specifically, Fig. 2A is a sectional view of the nose
on a surface perpendicular to the rotating shaft of the crossflow fan according to
the first example, and Fig. 2B is a sectional view of the nose
on a surface (a surface including the rotating shaft 13 of the impeller 12, that is,
a cross-sectional surface taken along line E-E of Fig. 2A) perpendicular to a circumferential
direction of the impeller of the crossflow fan according to the first example.
[0015] As shown in Figs. 2 and 3, the nose 6 is provided with an air passage constituting
portion 17 and a tongue 18. The air passage constituting portion 17 constitutes a
portion of an air passage inside the air conditioner and serves as a drain which receives
water droplets dripping from the heat exchanger 5 so as to be discharged. The tongue
18, provided along a portion of the outer circumference of the impeller 12, maintains
a pressure difference between a suction side B and a discharge side A which is generated
by the rotation of the impeller 12, so that the crossflow fan obtains high efficiency.
In the tongue 18, a plurality of concave slits 21 are arranged in the direction of
the rotating shaft 13 of the impeller 12 such that the tongue 18 is formed in a comb
shape. In the comb shape, the cross-section of the tongue 18 on a surface (a surface
including the rotating shaft 13 of the impeller 12, that is, a cross-sectional surface
taken along line E-E of Fig. 2A) perpendicular to a circumferential direction of the
impeller 12 has a plurality of convex portions which are connected to a base
and on the same side of the corresponding base. Some slits 21 among the plurality
of slits 21 are formed in a different shape, and have a different depth H in a radius
direction of the impeller 12 at the discharge side A. The remaining slits 21 are formed
to have the same shape and same depth H in a radius direction of the impeller 12 in
the discharge side A. The depths H of some slits 21 may be changed irregularly or
regularly in the discharge side A.
[0016] In the crossflow fan shown in the first example, all the slits 21 do not necessarily
need to be formed to have a different shape. However, at least some slits 21 among
the plurality of slits 21 may be formed to have a different shape and may have a different
depth H in the radius direction of the impeller 12 at the discharge side A. Further,
all the slits 21 may be formed in a different shape and the depths H thereof in the
radius direction of the impeller 12 in the discharge side A may differ from each other.
In all the slits 21, respective lengths L in a circumferential direction of the impeller
12, widths D in the direction of the rotating shaft 13, and distances T between the
adjacent slits 21 are identical.
[0017] In the crossflow fan shown in the first example, the tongue 18 is provided with the
plurality of slits 21 such that the cross-section of the tongue 18 on a surface perpendicular
to the circumferential direction of the impeller 12 is formed in a comb shape. Further,
at least some slits 21 among the plurality of slits 21 have a different depth H in
the radius direction of the impeller 12. Therefore, it is possible to change a pressure
loss in each of the slits 21 and to change the flow rate and the direction of leakage
flow from the discharge side (high-pressure side) A to the suction side (low-pressure
side) B for each position of the slits 21. Therefore, since an interference position
between leakage flow and the impeller blade 15 differs in each of the slits 21, an
area correlated with pressure fluccuation (an area of a region having synchronism)
can be reduced, and noise of the crossflow fan can be reduced while efficiency is
maintained.
[0018] Since a leakage flow rate differs for each position of the slits 21, a suction flow
and a leakage flow meet each other, and the strength and position of shear disturbance
of flow flowing in the impeller 12 differs in the circumferential direction of the
impeller 12. Therefore, an area correlated with pressure fluctuation (an area of a
region having synchronism) is reduced, which makes it possible to reduce noise.
[0019] In the crossflow fan, a flow rate is reduced in the vicinities of the side plates
14 provided at both ends in a direction of the rotating shaft 13 of the impeller 12
and in the middle thereof. When a leakage flow rate is large in the low flow rate
region, a reverse flow easily occurs, thereby decreasing efficiency. Therefore, the
slits 21, in which the depths H at the discharge side A are small, are provided in
the low flow rate region flowing through the impeller 12, and the slits 21, in which
the depths H at the discharge side A are large, are provided in a high flow rate region.
Then, it is possible to provide a crossflow fan without reducing efficiency caused
by a reverse flow and without increasing noise in any position in the direction of
the rotating shaft 13 of the impeller 12. That is, the depths H of the slits 21 at
the discharge side A may be decreased in the vicinities of the side plates 14 provided
at both ends and the middle of the rotating shaft 13 of the impeller 12, and the depths
H of the slits 21 at the discharge side A may be increased in other regions.
[0020] Fig. 4 is a sectional view of the nose on a surface perpendicular to the circumferential
direction of the impeller of the crossflow fan according to the first example.
[0021] In Fig. 2B, the slits 21 have been illustrated, of which the cross sections on a
surface perpendicular to the circumferential direction of the impeller 12 are formed
in
a rectangular shape. However, the cross-sections of the slits 21 may be formed in
any shape. That is, the cross-sectional surfaces of the slits 21 may be formed in
a triangle shape shown in Fig. 4A or in a trapezoidal shape shown in Fig. 4B. Further,
plural types of cross-sectional shapes may be combined. Similarly, the cross-section
on a surface perpendicular to the radius direction of the impeller may be formed in
any shape. That is, the cross-section may be formed in a rectangular shape, a triangle
shape, or a trapezoidal shape. Further, plural types of cross-sectional shapes may
be combined. When plural types of cross-sectional shapes are combined, a pressure
loss of each slit 21 may be changed.
[0022] In the crossflow fan shown in the first example, the lengths L in the circumferential
direction of the impeller 12, the widths D in the direction of the rotating shaft
13, and the distances T between the adjacent slits 21 are set to be respectively identical
in all of the slits 21. However, the lengths L in a circumferential direction of the
impeller 12, the widths D in the direction of the rotating shaft 13, and the distances
T between the adjacent slits 21 may differ from each other.
Second Example
[0023] In the first example, the air conditioner using the crossflow fan in which at least
some slits among the
plurality of slits have a different depth H in the radius direction of the impeller
12 is shown. In a second example, an air conditioner using a crossflow fan in which
at least some slits among a plurality of slits have a different length L in a circumferential
direction of the impeller 12 is shown.
[0024] Fig. 5 is a sectional view of a nose on a surface perpendicular to a rotating shaft
of the crossflow fan according to the second example, and Fig. 6 is a perspective
view of the nose of the crossflow fan according to the second example.
[0025] As shown in Figs. 5 and 6, a tongue 18 has a plurality of slits 22 arranged in a
direction of the rotating shaft 13 of the impeller 12 such that the cross-section
of the tongue 18 on a surface (including the rotating shaft 13 of the impeller 12)
perpendicular to the circumferential direction of the impeller 12 is formed in a comb
shape. Some slits 22 among the plurality of slits 22 are formed in a different shape
and have a different length L in the circumferential direction of the impeller 12.
The remaining slits 22 are formed in the same shape and have an identical length L
in the circumferential direction of the impeller 12. With the above exception, the
construction and functions of the air conditioner are the same as those of the air
conditioner shown in the
first example.
[0026] In the crossflow fan shown in the second example, all of the slits 22 can have the
same shape, but at least some of the slits 22 among the plurality of slits 22 may
be formed to have a different shape and a different length L in the circumferential
direction of the impeller 12. Further, all the slits 22 may be formed to have a different
shape from each other, and the lengths L thereof in the circumferential direction
of the impeller 12 may differ from each other in all the slits 22. Moreover, in all
the slits 22, respective depths H in the radius direction of the impeller 12, widths
D in the direction of the rotating shaft 13, and distances T between the adjacent
slits 22 are identical.
[0027] In the crossflow fan shown in the second example, the tongue 18 is provided with
the plurality of slits 22 such that the cross-section thereof on a surface perpendicular
to the circumferential direction of the impeller 12 is formed in a comb shape, and
at least some slits 22 among the plurality of slits 22 have a different length L in
the circumferential direction of the impeller 12. Therefore, by changing the length,
a pressure loss in each of the slits 22 can be changed, and a flow rate and direction
of leakage flow from the discharge side (high-pressure side) A to the suction side
(low-pressure side) B
can be different for each position of the slits 22. Therefore, since an interference
position between leakage flow and the impeller blade 15 differs in each of the slits
22, an area correlated with pressure fluctuation (an area of a region having synchronism)
can be reduced, and noise of the crossflow fan can be reduced while efficiency is
maintained.
[0028] Since a leakage flow rate differs for each position of the slits 22, a suction flow
and a leakage flow meet each other, and the strength and position of shear disturbance
of flow flowing in the impeller 12 differs in the circumferential direction of the
impeller 12. Therefore, an area correlated with pressure fluctuation (an area of a
region having synchronism) is reduced, which makes it possible to reduce noise.
[0029] Fig. 7 is a perspective view of the nose of the crossflow fan according to the second
example.
[0030] In the crossflow fan shown in Fig. 6, the lengths L of the slits 22 in the circumferential
direction of the impeller 12 are irregularly changed in the direction of the rotating
shaft 13. However, although the lengths L of the slits 22 in the circumferential direction
of the impeller 12 are regularly changed as shown in Fig. 7, it
is possible to obtain the same effect as the lengths L are irregularly changed.
[0031] Further, the slits 22, in which the lengths L in the circumferential direction of
the impeller 12 are small, are provided in a low flow rate region flowing through
the impeller 12, and the slits 22, in which the lengths L in the circumferential direction
of the impeller 12 are large, are provided in a high flow rate region, which makes
it possible to provide a crossflow fan in without reducing the efficiency caused by
a reverse flow and without increasing noise in any position in a direction of the
rotating shaft 13 of the impeller 12. That is, the lengths L of the slits 22 may be
reduced in the vicinities of the side plates 14 provided at both ends and the middle
of the rotating shaft 13 of the impeller 12, and the lengths L of the slits 22 may
be increased in other regions.
[0032] In the crossflow fan shown in the second example, the depths H in the radius direction
of the impeller 12, the widths D in the direction of the rotating shaft 13, and the
distances T between the adjacent slits 22 are set to be respectively identical in
all of the slits 22. However, the depths H in the radius direction of the impeller
12, the widths D in the direction of the rotating shaft 13, and the distances T between
the adjacent slits
22 may respectively differ.
Third Example
[0033] In the first example, the air conditioner using the crossflow fan in which at least
some slits among the plurality of slits have a different depth H in the radius direction
of the impeller 12 is shown. In a third example, an air conditioner using a crossflow
fan in which at least some slits among a plurality of slits have a different width
D in a direction of the rotating shaft 13 of the impeller 12 is shown.
[0034] Fig. 8 is a perspective view illustrating a nose of the crossflow fan according to
the third example.
[0035] As shown in Fig. 8, a tongue 18 has a plurality of slits 23 arranged in a direction
of the rotating shaft 13 of the impeller 12 such that the cross-section of the tongue
18 on a surface (including the rotating shaft 13 of the impeller 12) perpendicular
to the circumferential direction of the impeller 12 is formed in a comb shape. Some
slits 23 among the plurality of slits 23 are formed to have a different shape and
a different width D in the direction of the rotating shaft 13 of the impeller 12.
The remaining slits 23 are formed to have the same shape and an identical width D
in the direction of the rotating shaft 13 of the impeller 12. With the above exception,
the construction and functions of the air conditioner are the same as those of the
air conditioner shown in the first example.
[0036] In the crossflow fan shown in the third example, all of the slits 23 can be formed
in the same shape, but at least some slits 23 among the plurality of slits 23 may
be formed to have a different shape and may have a different width D in the direction
of the rotating shaft 13 of the impeller 12. Further, all the slits 23 may be formed
to have a different shape from each other, and the widths D in the direction of the
rotating shaft 13 of the impeller 12 may differ from each other in all of the slits
23. In all of the slits 23, the depths H in the radius direction of the impeller 12,
the lengths L in the circumferential direction thereof, and the distances T between
the adjacent slits 23 are respectively identical.
[0037] In the crossflow fan shown in the third example, the tongue 18 is provided with the
plurality of slits 23 such that the cross-section of the tongue 18 on a surface perpendicular
to the circumferential direction of the impeller 12 is formed in a comb shape, and
at least some slits 23 among the plurality of slits 23 have a different width D in
the direction of the rotating shaft 13 of the impeller 12. Therefore, a pressure loss
in each of the slits 23 can be changed, and a flow rate and direction of
leakage flow from the discharge side (high-pressure side) A to the suction side (low-pressure
side) B can he different for each position of the slits 23. Therefore, since an interference
position between the leakage flow and the impeller blade 15 differs in each of the
slits 23, an area correlated with pressure fluctuation (an area of a region having
synchronism) can be reduced, and noise of the crossflow fan can be reduced while efficiency
is maintained.
[0038] Since a leakage flow rate differs in each position of the slits 23, a suction flow
and a leakage flow meet each other, and the strength and position of shear disturbance
of flow flowing in the impeller 12 differs in the circumferential direction of the
impeller 12. Therefore, an area correlated with pressure fluctuation (an area of a
region having synchronism) is reduced, which makes it possible to reduce noise.
[0039] In the crossflow fan shown in the third example, the thickness of a material composing
the tongue 18 is uniform, as compared with the crossflow fans shown in the first and
second embodiments. Therefore, it is possible to easily mold the crossflow fan.
[0040] In the third example, the widths D of the slits 23 in the direction of the rotating
shaft 13 are irregularly changed as shown in Fig. 8. However, although
the widths D of the slits 23 in the direction of the rotating shaft 13 are regularly
changed in the direction of the rotating shaft 13, it is possible to obtain the same
effect as the widths that are irregularly changed.
[0041] The slits 23, in which the widths D in the direction of the rotating shaft 13 are
small, are provided in a low flow rate region flowing through the impeller 12, and
the slits 23, in which the widths D in the direction of the rotating shaft 13 are
large, are provided in a high flow rate region. Therefore, it is possible to provide
a crossflow fan without reducing efficiency caused by a reverse flow and without increasing
noise in any position in the direction of the rotating shaft 13 of the impeller 12.
That is, the depths D of the slits 23 may be decreased in the vicinities of the side
plates 14 provided at both ends and the middle of the rotating shaft 13 of the impeller
12, and the widths D of the slits 23 may be increased in other regions.
[0042] In the crossflow fan shown in the third example, the depths H in the radius direction
of the impeller 12, the lengths L in the circumferential direction, and the distances
T between the adjacent slits 23 are set to be respectively identical in all of the
slits 23. However, the depths H in the radius direction of the impeller 12, the lengths
L in the circumferential direction, and the
distances T between the adjacent slits 23 may respectively differ.
First Embodiment
[0043] In the first example, the air conditioner using the crossflow fan in which at least
some slits among the plurality of slits have a different depth H in a radius direction
of the impeller 12 is shown. In a first embodiment of the invention, an air conditioner
using a crossflow fan in which at least some slits among a plurality of slits are
provided with a rib is shown.
[0044] Fig. 9 is a perspective view of a nose of a crossflow fan according to the first
embodiment of the invention, and Fig. 10 is a sectional view of the nose on a surface
perpendicular to the rotating shaft of the crossflow fan according to the first embodiment
of the invention.
[0045] As shown in Figs. 9 and 10, a tongue has a plurality of slits 24 arranged in the
direction of the rotating shaft 13 of the impeller 12 such that the cross-section
of the tongue 18 on a surface (including the rotating shaft 13 of the impeller 12)
perpendicular to the circumferential direction of the impeller 12 is formed in a comb
shape. The plurality of slits 24 are provided with ribs 25 which blocks leakage flow
so as to bury portions of the slits 24. Further, some slits 24 among the
plurality of slits 24 are formed to have a different shape, and the positions of the
ribs 25 differ in the circumferential direction of the impeller 12. The remaining
slits 24 are formed in the same shape, and the positions of the ribs 25 are identical
in the circumferential direction of the impeller 12. With the above exception, the
construction and functions of the air conditioner are the same as those of the air
conditioner shown in the first example.
[0046] In the crossflow fan shown in the first embodiment, all of the slits 24 do not necessarily
need to be formed to have a different shape, but at least some slits 24 among the
plurality of slits 24 may be formed in a different shape and the positions of the
ribs 25 may differ in the circumferential direction of the impeller 12. Further, all
of the slits 24 may be formed to have a different shape, and the positions of the
ribs 25 in the circumferential direction of the impeller 12 may differ from each other
in all of the slits 24. In all of the slits 24, the depths H in the radius direction
of the impeller 12, the lengths L in the circumferential direction thereof, the widths
D in the direction of the rotating shaft 13, and the distances T between the adjacent
slits 24 are respectively identical.
[0047] In the crossflow fan shown in the first embodiment,
the tongue 18 is provided with the plurality of slits 24 such that the cross-section
of the tongue 18 on a surface perpendicular to the circumferential direction of the
impeller 12 is formed in a comb shape. Further, the plurality of slits 24 have the
ribs 25, and the positions of the ribs 25 of at least some slits 24 differ in the
circumferential direction of the impeller 12. Therefore, a pressure loss in each of
the slits 24 can be changed, and a flow rate and direction of leakage flow from the
discharge side (high-pressure side) A to the suction side (low-pressure side) B can
be different for each position of the slits 24. Therefore, since an interference position
between leakage flow and the impeller blade 15 differs In each of the slits 24, an
area correlated with pressure fluctuation (an area of a region having synchronism)
can be reduced, and noise of the crossflow fan can be reduced while efficiency is
maintained.
[0048] Since a leakage flow rate differs in each position of the slits 24, a suction flow
and a leakage flow meet each other, and the strength and position of shear disturbance
of flow flowing in the impeller 12 differs in the circumferential direction of the
impeller 12. Therefore, an area correlated with pressure fluctuation (an area of a
region having synchronism) is reduced, which makes it possible to reduce noise.
[0049] In the air conditioner shown in the first embodiment, water generated at the time
the air conditioner is on can be held by the rib 25 as well as by surface tension
of the slit 24, which makes it possible to strengthen a water-retaining force. Therefore,
the accumulation of dew drops is minimized.
[0050] Fig. 11 is a perspective view of the nose of the crossflow fan according to the first
embodiment of the invention.
[0051] In the first embodiment, the positions of the ribs 25 in the circumferential direction
of the impeller 12 are irregularly changed in the direction of the rotating shaft
13, as shown in Fig. 9. However, although the positions of the ribs 25 in the circumferential
direction of the impeller 12 are regularly changed in the direction of the rotating
shaft 13 as shown in Fig. 11, it is possible to produce the same effect when the positions
are irregularly changed.
[0052] Fig. 12 is a cross-sectional view of the nose on a surface perpendicular to the rotating
shaft of the crossflow fan according to the first embodiment of the invention.
[0053] In the crossflow fans shown in Figs. 9 and 10, the positions of the ribs 25 in the
plurality of slits 24 are changed, and a flow rate and direction of leakage flow are
changed. However, even though all of the ribs 25 of the slits 24 are provided in the
same position, angles of the ribs 25 are changed, and a flow rate and direction of
leakage flow are changed as shown in Figs. 12A and 12B, it is possible to produce
the same effect as those of the crossflow fans shown in Figs. 9 and 10.
[0054] Fig. 13 is a sectional view of the nose of the crossflow fan according to the first
embodiment of the invention. Specifically, Fig. 13A is a sectional view of the nose
on a surface perpendicular to the rotating shaft of the crossflow fan according to
the first embodiment of the invention, and Fig. 13B is a sectional view of the nose
of the crossflow fan on a surface (a surface including the rotating shaft, that is,
a cross-section taken along line F-F of Fig. 13A) perpendicular to the circumferential
direction of the impeller of the crossflow fan according to the first embodiment of
the invention.
[0055] In Fig. 13, all of the ribs 25 of the slits 24 are positioned in the same position,
similar to the ribs shown in Fig. 12. Further, the heights Hr of the ribs 25 are changed,
and a flow rate and direction of leakage flow are changed. Although the ribs 25 of
the slits 24 are positioned in the same position and the heights Hr of the ribs are
changed, it is possible to produce the same effect as those of the crossflow fans
shown in Figs. 9 and
10.
[0056] The ribs 25 do not need to be installed in all of the slits 24, but may be installed
in only some of the slits 24. Further, when the ribs 25 are installed only in some
slits 24, the respective positions, angles, and heights of the ribs 25 in the circumferential
direction of the impeller 12 may be identical in the slits 24. Since only some slits
24 have the rib 25, a pressure loss can be changed by the presence or absence of the
rib 25, and a flow rate and direction of leakage flow from the discharge side (high-pressure
side) A to the suction side (low-pressure side) B can be different for each position
of the slits 24. Therefore, since an interference position between leakage flow and
the impeller blade 15 differs for each of the slits 24, an area correlated with pressure
fluctuation (an area of a region having synchronism) can be reduced, and noise of
the crossflow fan can be reduced while efficiency is maintained. Further, since a
leakage flow rate differs in each position of the slits 24, a suction flow and a leakage
flow meet each other, and the strength and position of shear disturbance of flow flowing
in the impeller 12 differs in the circumferential direction of the impeller 12. Therefore,
an area correlated with.pressure fluctuation (an area of a region having synchronism)
is reduced, which makes it possible to reduce noise. Therefore, in the crossflow fan
shown in the first embodiment, at least some slits 24 may have the rib 25.
[0057] In the cross flow fan shown in the first embodiment, the depths H in the radius direction
of the impeller 12, the lengths L in the circumferential direction, the widths D in
the direction of the rotating shaft 13, and the distances T between the adjacent slits
24 are set to be respectively identical in all of the slits 24. However, the depths
H in the radius direction of the impeller 12, the lengths L in the circumferential
direction, the widths D in the direction of the rotating shaft 13, and the distances
T between the adjacent slits 24 may differ respectively.