JP2001159396A - Centrifugal fan and air conditioner equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal fan and an air conditioner equipped with the centrifugal fan with reduced noises and ensuring high blowing efficiency in a small air quantity area. SOLUTION: A front edge 4a of a blade 4 is provided with a first straight line part 4a1 positioned on the hub 2 side from a cardinal point 10 set in a specified intermediate position between the hub 2 and a shroud 3, with its ridgeline extending forward from the cardinal point 10 toward an end part 11 on the hub 2 side, and a second straight line part 4a2 positioned on the shroud 3 side from the cardinal point, with its ridgeline extending almost parallel with the axial direction of the centrifugal fan 1. Air flow that flows into the front edge 4a of the blade 4 thereby collides with the cardinal point part 10 to form a longitudinal vortex 21 gradually growing from the cardinal point 10 toward the rear edge 4b side. The growth of a boundary layer of air at the negative pressure face of the blade 4 is suppressed by the energy of the longitudinal vortex. Blowing noise is thereby reduced, and flowing efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal fan and an air conditioner provided with the centrifugal fan.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional centrifugal fan 50.
Are shown. The centrifugal fan 50 includes a motor 5
6 and an outer peripheral portion of a shroud 52 which is provided with a suction port 54 at a central portion thereof and which is opposed to the hub 51 at a predetermined interval. A plurality of blades 53, 5 having a plate shape
Are arranged at predetermined intervals in the circumferential direction of the hub 51 and the shroud 52. In the centrifugal fan 50, when the centrifugal fan 50 is driven to rotate by the motor 56, the air sucked from the suction port 54 is supplied to the blade 53 at the front edge 53 a side as shown by a stream line A in FIG. And flows toward the trailing edge 3b side, and is blown radially outward from a blow-out port 55 opened on the outer peripheral surface of the centrifugal fan 50.

Incidentally, such a conventional centrifugal fan 5
In 0, as shown in the figure, the front edge 53a of the blade 53, the straight portion 53a ₁ of the ridge line extending substantially parallel to the axial direction of the centrifugal fan 50 from the hub side edge 53c, the shroud-side edge and the ridge line located 53d closer is constituted by an inclined portion 53a ₂ which is inclined obliquely. Therefore, the boundary between the straight portion 53a ₁ and the inclined portion 53a ₂ corners 5
3e are formed, and the corners 53e are
A vertical vortex 57 is generated in the airflow flowing into the air, and the energy of the vertical vortex is transferred to the shroud side edge 53d of the blade 53.
The growth is suppressed by supplying to the boundary layer on the near negative pressure surface, thereby preventing the separation of the air as much as possible, thereby contributing to the reduction of the blowing noise in the centrifugal fan 50 and the improvement of the blowing efficiency.

[0004]

However, as shown by streamline A in FIG. 7, the main flow of the air flow in the centrifugal fan 50 is more deviated toward the hub side edge 53c than the corner 53e of the blade 53. Flowing. Therefore, the corner 53e
The separation suppressing effect of the blade 5 is mainly transmitted from the outlet side space through an annular gap between the suction port 54 and a bell mouth (not shown) disposed substantially coaxially inside the suction port 54.
Although acting as suppressing this for peeling of the air flow caused by the leakage flow entering the third shroud side edge 53d side portion, of the air flow through the substantially central portion of the straight portion 53a ₁ of the blade 53 It has little effect on mainstream parts.

[0005] In this case, it is considered to act on the main part of the separation preventing effect the angle portion 53e by increasing the inclined portion 53a ₂ by the corner portion 53e is set to the hub side edge 53c toward Thus, the inclined portion 53a
_{If 2} is increased, the blade area of the blades 53 is reduced accordingly, and the air blowing efficiency of the blades 53 as a whole is lowered, which is not advantageous.

For this reason, conventionally, the inclined portion 53a ₂
Is located near the shroud-side edge 53d, where separation is likely to occur due to leakage flow of air on the blowing side from a gap between the edge of the suction port 54 and a bell mouth (not shown) provided at the suction port 54. It is customary to provide only a relatively limited portion and expect the effect of the corner 53e in that portion.

Therefore, in the conventional centrifugal fan 50, in the main flow flowing from the vicinity of the center of the leading edge 53a of the blade 53 and flowing toward the hub-side edge 53c, an air flow separation phenomenon still remains. , Centrifugal fan 5
When viewed as a whole, there is room for improvement in terms of its blowing noise and blowing efficiency.

Further, among the airflows flowing into the leading edge 53a of the blade 53, the airflow particularly flowing into the portion of the leading edge 53a near the hub 51 has a relatively low flow rate, and therefore, particularly in the small air volume region. In this case, the inflow into the blade 53 side is poor, and as a result, this is one of the factors that hinder the air blowing efficiency of the centrifugal fan 50.

SUMMARY OF THE INVENTION The present invention has been made to provide a centrifugal fan with low noise and high air-blowing efficiency especially in a small air volume region, and an air conditioner provided with the centrifugal fan. is there.

[0010]

Means for Solving the Problems In the present invention, the following configuration is adopted as specific means for solving such problems.

In the first invention of the present application, the shroud 3 having the suction port 5 at the center while the blades 4 are fixedly arranged in an upright state on the outer periphery of the hub 2 that is driven to rotate is connected to the hub 2. A front edge 4a of the blade 4 is located between the hub 2 and the shroud 3 at a predetermined position between the hub 2 and the hub 2 with respect to the centrifugal fan. a first linear portion 4a ₁ to advance along with and its ridge located deviation is directed from the base point 10 to the end 11 of the hub 2 side, and the ridge line that is located above the shroud 3 closer than the base point 10 There is characterized in that a second linear portion 4a ₂ extending substantially parallel to the axial direction of the centrifugal fan 1.

The second invention of the present application is characterized in that in the centrifugal fan according to the first invention, the base point 10 is set at an inflow portion of the main airflow at the front edge 4a.

In the third invention of the present application, the first or the second
In the centrifugal fan according to the invention, the leading edge of the blade 4
The first straight portion 4a in 4a₁Entrance angle θ₁And the front half
Diameter R ₁To the second linear portion 4a_TwoEntrance angle θ_TwoAnd leading edge half
Diameter R_TwoIt is characterized by having been set to be substantially equivalent to.

According to a fourth aspect of the present invention, in the air conditioner having the centrifugal fan 1 and the heat exchanger 32 disposed in the casing 31, the centrifugal fan 1 is replaced with the first, second, or second centrifugal fan. The invention is characterized in that the centrifugal fan 1 according to the third aspect of the invention is applied.

[0015]

According to the present invention, the following effects can be obtained by adopting such a configuration.

In the centrifugal fan according to the first invention of the present application, the front edge 4 a of the blade 4 is located closer to the hub 2 than a base point 10 set at a predetermined position between the hub 2 and the shroud 3. a first linear portion 4a ₁ to advance along with the ridge extending from the base point 10 to the end 11 of the hub 2 side, the centrifugal fan and its ridge line located on the shroud 3 closer than the base point 10 1 and a substantially a second linear portion 4a ₂ extending parallel to the axial direction.

[0017] Thus, in the centrifugal fan 1 according to the present invention, and the first linear portion 4a ₁ ridgeline and the second ridgeline linear portion 4a ₂ in the base 10 of the front edge 4a is here becomes discontinuous It becomes a corner. Therefore, this base point 1
When the air flow flows into the zero point, the air flow is disturbed by the collision with the base point 10 part, and the air flow is disturbed on the surface of the negative pressure surface of the blade 4 from the base point 10 part of the leading edge 4a. A longitudinal vortex 21 that gradually grows toward the trailing edge 4b is generated. The energy of the longitudinal vortex is supplied to the boundary layer of air on the suction surface, whereby the growth of the boundary layer is suppressed, and the separation of air on the suction surface is prevented as much as possible. In the centrifugal fan 1, the blowing noise is reduced and the blowing efficiency of the blades 4 as a whole is increased.

Furthermore, the first linear portion 4a _1, since the ridge is a form of advanced along with towards the end 11 of the hub 2 side from the base 10, of the blade 4, the in the portion corresponding to the first linear portion 4a _1, the chord length is longer than the second portion corresponding to the straight portions 4a _2, as a result, the air flow into the first linear portion 4a ₁ part The longer the chord length, the more the flow is stabilized. Further, the by the first linear portion 4a ₁ is positioned in the hub 2 toward actively blade 4 side by the first linear portion 4a ₁ part slow air flow with a flow rate flowing through the hub 2 toward moves forward And the flowability into the blades 4 is improved. By the synergistic action of these two, the air blowing efficiency of the centrifugal fan 1, particularly the air blowing efficiency in a small air volume region is improved.

According to the centrifugal fan according to the second invention of the present application, in the centrifugal fan according to the first invention, the base point 10 is set at the inflow portion of the main airflow at the leading edge 4 a of the blade 4. Therefore, the separation effect of the air flow by the vertical vortex 21 generated by the base point 10 portion acts intensively on the main flow portion of the air flow. As a result, in the centrifugal fan 1, the separation of the air flow is suppressed. It works more effectively, and the reduction of the blowing noise and the improvement of the blowing efficiency are further promoted.

The centrifugal fan according to the third invention of the present application
According to the above, the centrifugal fan according to the first or second aspect of the invention
The first straight line at the leading edge 4a of the blade 4
Part 4a₁Entrance angle θ₁And leading edge radius R₁To the second linear portion
4a_TwoEntrance angle θ_TwoAnd leading edge radius R_TwoAnd set it approximately equal to
Therefore, the effects described above or above can be more reliably
Become. That is, of the front edge 4a of the blade 4, the second straight
Line part 4a_TwoIs originally a separation of the airflow at the leading edge (ie
Edge angle θ so that edge separation does not occur._TwoAnd leading edge half
Diameter R_TwoIs set. Therefore, above the base point 10
The above-mentioned first form having a form of moving forward as going toward the hub 2 side.
1 straight section 4a₁Entrance angle θ₁And leading edge radius R ₁And the first
Straight part 4a₁The second straight portion 4 corresponding to the forward mode of
a_TwoEntrance angle θ_TwoAnd leading edge radius R_TwoWhen changed from
1st linear part 4a₁Leading edge peeling may occur in parts
However, as in the present invention, the first linear portion 4a₁Entering
Mouth angle θ₁And leading edge radius R₁And the second linear portion 4a_TwoEntrance
Angle θ_TwoAnd leading edge radius R_TwoWhen set to be substantially equal to
Line part 4a₁At the leading edge, which prevents
Or the effects described in
You.

According to the air conditioner of the fourth aspect of the present invention, in the air conditioner configured by disposing the centrifugal fan 1 and the heat exchanger 32 in the casing 31, Since the centrifugal fan 1 according to the second or third aspect of the present invention is applied, an air conditioner having both quiet operation and high-level air conditioning performance can be obtained based on the characteristics of the centrifugal fan 1. is there.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a centrifugal fan and an air conditioner according to the present invention will be specifically described based on preferred embodiments.

A: Centrifugal fan FIGS. 1 and 2 show a centrifugal fan 1 according to an embodiment of the present invention. The centrifugal fan 1 is provided with a motor 7 connected to a central portion thereof and rotatably driven by the motor 7, and has a suction port 5 at the central portion thereof and coaxially faces the hub 2 at a predetermined interval. A shroud 3 is provided, and a plurality of blades 4, 4,... Are arranged in an upright state so as to extend between the inner surface of the hub 2 and the inner surface of the shroud 3. The outer peripheral portions of the hub 2 and the shroud 3 and the respective blades 4, 4,.
-An outlet 6 is formed at the intermediate position.

The vane 4 forms the gist of the present invention, and has a curved plate-like basic shape that smoothly curves from the front edge 4a to the rear edge 4b as shown in FIGS. And are integrally formed of an appropriate resin material.

In the blade 4, the front edge 4a of the blade 4 is set at a base 10 which is set at an appropriate position between the hub 2 and the shroud 3 on the front edge 4a.
The position to said hub 2 nearer 0 1 straight portions 4a ₁ and the second located above the shroud 3 closer than the base point 10
And two straight portions of the linear portion 4a _2, than the second linear portion 4a ₂ are constituted by an inclined portion 4a ₃ located above the shroud 3 closer. The set position of the base point 10 is set at a position corresponding to the mainstream portion of the airflow flowing toward the front edge 4a of the blade 4.

[0026] The first linear portion 4a _1, as shown in FIGS. 2 to 4, which forms a hub-side edge 4c closer portion of the front edge 4a, the hub-side end of the base 10 The ridge is gradually inclined toward the end 11 on the side of the edge 4c. It said second linear portion 4a ₂ is for constituting the intermediate portion of the front edge 4a, the ridge is substantially parallel to the axial direction of the centrifugal fan 1 from the base point 10 toward the shroud 3 side It is a straight line extending.

Therefore, as shown in FIGS. 2 and 4, in the blade 4, when a portion corresponding to the first linear portion 4 a ₁ is compared with a portion corresponding to the second linear portion 4 a ₂ , portion corresponding to the first linear portion 4a ₁ will have a triangular forward portion 14 forward than the front edge position of the second linear portion 4a _2. Further, as shown in FIG.
The first straight portion 4a ₁ defines the entrance angle θ ₁ and the leading edge radius R ₁ ,
Also the second linear portion 4a ₂ and the inlet angle theta ₂ and the leading edge radius R _2, but having respectively, in this embodiment, the inlet of the first linear portion 4a ₁ despite having a forward mode the angle theta ₁ and the leading edge radius R _1, is set substantially equal to the inlet angle theta ₂ and the leading edge radius R ₂ of the second linear portion 4a _2. The inlet angle θ ₂ and the leading edge radius R ₂ of the second linear portion 4a ₂ are set based on the design concept of the inlet angle and leading edge radius of the blade in a conventional general centrifugal fan. Originally, the entrance angle and the leading edge radius are set so as not to cause the leading edge separation. Accordingly, by setting the entrance angle θ ₁ and the leading edge radius R ₁ of the first linear portion 4a ₁ to be substantially equal to the entrance angle θ ₂ and the leading edge radius R _{2 of} the second linear portion 4a ₂ , 1
It will have an inlet angle and the leading edge radius, such as not to cause the front edge peeling linear portion 4a _1.

[0028] The inclined portion 4a ₃ is for constituting the shroud 3 toward the portion of the leading edge 4a, the ridge line, the second from the shroud side edge 4d of the wing 4
Be one that is inclined toward the shroud side end portion of the linear portion 4a _2, the boundary portion between the second end of the linear portion 4a ₂ is a corner portion 12.

In the centrifugal fan 1 having the blades 4, 4,... Configured as described above, the following specific operation and effect can be obtained.

That is, in the centrifugal fan 1 of this embodiment, the leading edge 4a of the blade 4 is located closer to the hub 2 than the base point 10 and its ridge is located at an end from the base point 10 on the hub 2 side. first the linear portion 4a ₁ to advance along with towards the part 11, second linear portion 4a and the ridge line located on the shroud 3 closer than the base point 10 extends substantially parallel to the axial direction of the centrifugal fan 1 ₂ and the second linear portion 4a ₂
The inclined portion 4a closer to the shroud 3
It consists of _three .

[0031] Therefore, when the centrifugal fan 1 is rotated driven by the motor 7, the main flow of the air sucked from the suction port 5, as shown by flow lines A ₁ in FIG. 2, the blade 4 The air flows into the front edge 4a from the vicinity of the base point 10 and is blown out from the rear edge 4b to the air outlet 6.
In this case, the air flow is disturbed by the collision of the air flow with the base point 10, and as shown in FIG. 4, on the surface of the negative pressure surface of the blade 4, the base point on the leading edge 4 a side is formed. A vertical vortex 21 that grows gradually from 10 toward the trailing edge 4b is generated. By supplying the energy of the longitudinal vortex 21 to the boundary layer of air on the negative pressure surface of the blade 4,
The growth of the boundary layer is suppressed, and the separation of air on the negative pressure surface is prevented as much as possible.

As shown by a stream line A ₂ in FIG. 2, after being sucked from the suction port 5, the airflow flowing toward the shroud-side edge 4 d of the blade 4 is reduced by the second straight portion 4.
As shown in FIG. 4, the vertical vortex 22 that flows while growing gradually from the corner 12 toward the trailing edge 4 b side by colliding with the corner 12 at the boundary between the a ₂ and the inclined portion 4 a ₃ . Generate. The vertical vortex 22 suppresses the separation of air generated at a portion of the negative pressure surface of the blade 4 near the shroud-side edge 4d. In this case, the portion of the blade 4 near the shroud-side edge 4d is a region where separation is likely to occur due to a leak flow flowing from the outlet side space between the suction port 5 and a bell mouth (not shown). The effect of the vertical vortex 23 is great.

The vertical vortex 21 generated by the base point 10 suppresses the separation of the air flow and the corner 1
As a synergistic effect with the effect of suppressing the separation of the airflow by the vertical vortex 22 generated by the second vortex 2, the centrifugal fan 1 reduces the blowing noise and improves the blowing efficiency.

On the other hand, the first straight portion 4a₁Is the ridgeline
Moves from the base point 10 toward the end 11 on the hub 2 side.
Since it is configured to move forward with this, the blade 4
The first straight portion 4a₁In the part corresponding to
The second straight portion 4a_TwoAbove the advancement part than the corresponding part
The chord length is increased by the amount of the minute 14, and as a result,
1 straight section 4a₁The airflow entering the section is long chord length
Therefore, the flow is stabilized. In addition, the above-mentioned blade 4
The first straight portion 4a at a position close to the hub 2₁Is located
Since the advancing portion 14 exists here,
The low-velocity airflow flowing near the valve 2
Will be actively scraped to the blade 4 side
And the inflow of the air flow into the blades 4 is improved.
The effect is remarkable in the region. Further, the first
Straight part 4a₁Entrance angle θ₁And leading edge radius R ₁Is the second
Line part 4a_TwoEntrance angle θ_TwoAnd leading edge radius R_TwoSet almost the same as
The first straight portion 4a₁Leading edge stripping in
Separation is prevented as much as possible. Synergistic effect of each of these actions
As a result, the centrifugal fan 1 has a low blowing noise.
Blow efficiency, especially in the small air volume region, while maintaining the reduction effect
Will be improved.

FIG. 6 shows a comparison between the blowing sound and the static pressure of the centrifugal fan 1 and those of the conventional centrifugal fan. Here, in each of the “air volume-blowing sound characteristic diagram” and the “air volume-static pressure characteristic diagram”, symbols L ₁ and L ₂ indicate the characteristics of the centrifugal fan 1 according to this embodiment, and symbols L ₁₁ and L _21. Indicates the characteristics of the conventional centrifugal fan. From FIG. 6, the centrifugal fan 1 of this embodiment has characteristics of lower blowing sound and higher static pressure as compared with the centrifugal fan having the conventional structure. It can be seen that the effect is remarkable in the small air volume region.

B: Air Conditioner FIG. 5 shows an air conditioner Z provided with the centrifugal fan 1 according to the first embodiment as an example of an air conditioner provided with the centrifugal fan according to the present invention. Is shown.
The air conditioner Z is an indoor unit of a separate type air conditioner embedded and arranged in a ceiling 35 and has a casing 3.
1, the centrifugal fan 1 is disposed with its suction port 5 facing downward, and a heat exchanger 32 is disposed on the outer peripheral side of the centrifugal fan 1 so as to face the air outlet 6. It is composed. Then, by the operation of the centrifugal fan 1, the indoor air sucked from the suction port 33 provided at the center of the lower surface 31 a of the casing 31 is transferred to the heat exchanger 3
After the heat is exchanged into hot air or cold air in 2, the air is blown into the room from an air outlet 34 provided on the outer peripheral portion of the lower surface 31a.

In this air conditioner Z, by providing the centrifugal fan 1 according to the present invention as a centrifugal fan, the characteristics of the centrifugal fan 1 as described in each of the above embodiments, that is, the blowing noise is low and An air conditioner having both quiet operation and high air-conditioning performance can be obtained based on the characteristic that high air blowing efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a centrifugal fan according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part II-II in FIG.

FIG. 3 is an enlarged sectional view taken along the line III-III of FIG. 2;

FIG. 4 is an enlarged perspective view of a blade of the centrifugal fan shown in FIG. 2;

FIG. 5 is a cross-sectional view of the air conditioner according to the present invention.

FIG. 6 is a characteristic diagram of “air volume—blowing sound / static pressure” of the centrifugal fan.

FIG. 7 is a sectional view of a main part of a conventional centrifugal fan.

[Explanation of symbols]

1 is a centrifugal fan, 2 is a hub, 3 is a shroud, 4 is a blade, 5 is a suction port, 6 is an outlet, 7 is a motor, 10 is a base point, 11 is an end, 12 is a corner, and 21 and 22 are vertical. Vortex, 3
1 is a casing, 32 is a heat exchanger, 33 is a suction port, 34
Is an outlet, 35 is a ceiling, L is a blade center line, θ ₁ and θ ₂ are inlet angles, R ₁ and R ₂ are leading edge radii, and Z is an air conditioner.

Claims (4)

[Claims] 1. A shroud (3) having a suction port (5) at a central portion thereof, wherein a blade (4) is fixedly arranged in an upright state on an outer peripheral portion of a hub (2) driven to rotate. (2) a centrifugal fan which is disposed opposite to the blade (4) with the blade (4) interposed therebetween, wherein a front edge (4a) of the blade (4) is formed between the hub (2) and the shroud (3); ) Set at a predetermined position in the middle of (1)
The first straight portion (4a ₁ ) which is located closer to the hub (2) than 0) and moves forward from the base point (10) toward the end (11) on the hub (2) side. And a second straight portion (4a ₂ ) which is located closer to the shroud (3) than the base point (10) and whose ridge line extends substantially parallel to the axial direction of the centrifugal fan (1). Features a centrifugal fan. 2. The centrifugal fan according to claim 1, wherein the base point (10) is set at the leading edge (4a) of the leading edge (4a). 3. An inlet angle (θ ₁ ) and a leading edge radius (R ₁ ) of the first linear portion (4a ₁ ) at a leading edge (4a) of the blade (4) according to claim 1 or 2, The entrance angle (θ ₂ ) and the leading edge radius (R) of the second linear portion (4a ₂ )
₂ ) A centrifugal fan characterized by being set substantially equal to that of ₂ ). 4. An air conditioner including a centrifugal fan (1) and a heat exchanger (32) arranged in a casing (31), wherein the centrifugal fan (1) is provided as a centrifugal fan (1). An air conditioner to which the centrifugal fan according to 2 or 3 is applied.