BELL-MOUTH STRUCTURE OF AIR BLOWER
A bell-mouth structure of an air blower provided around a blade wheel of an axial-flow air blower for guiding air from an air suction side of the blade wheel to an air blow-out side including an air blow-out wall portion that intercommunicates with an air blow-out opening and extends substantially along an axial direction of the blade wheel, and a slope wall portion that intercommunicates with the air blow-out wall portion and slopes to an air suction opening so as to expand in diameter. When the overall height of the bell-mouth is represented by H, the height of the slope wall portion is represented by h and a slope angle of the slope wall portion is represented by β, the bell mouth structure is configured so as to satisfy 0.33≦h/H≦0.42 and 60°≦β≦70°.
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The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2009-270342 filed on Nov. 27, 2009. The content of the application is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a bell-mouth structure of an air blower used in an air conditioner or the like.
2. Description of the Related Art
An axial-flow air blower such as a propeller fan or the like has been widely used as an air blower for an air conditioner or the like, and a bell-mouth for smoothly guiding air from an air suction side to an air blow-out side and reducing a leakage amount of air is provided around a blade wheel for blowing air. With respect to this type of air blower, it has been recently more strongly required to enhance the performance and reduce the noise, and a performance enhancing method based on an improvement of the bell-mouth shape has been proposed (for example, see JP-A-2004-211971).
Furthermore, it has been recently required to enhance the air flow amount of the air blower and reduce the driving force of the air blower (motor load) from the viewpoint of energy saving.
SUMMARY OF THE INVENTIONTherefore, an object of the present invention is to provide a bell-mouth structure of an air blower that can solve the problem of the technique described above, and also satisfy reduction of both of the rotational number and the driving force of the air blower at the same time with keeping the air flow amount equal.
In order to attain the above object, according to a first aspect of the present invention, a bell-mouth structure of an air blower that is provided around a blade wheel of an axial-flow air blower and guides air from an air suction side of the blade wheel to an air blow-out side of the blade wheel has an air blow-out wall portion that intercommunicates with an air blow-out opening and extends substantially along an axial direction of the blade wheel, and a slope wall portion that intercommunicates with the air blow-out wall portion and slopes to an air suction opening so as to expand in diameter, wherein when the overall height of the bell-mouth is represented by H, the height of the slope wall portion is represented by h and a slope angle of the slope wall portion is represented by β, 0.33≦h/H≦0.42 and 60°≦β≦70° are satisfied.
In this construction, when the diameter of an opening of a connecting portion between the air blow-out wall portion and the slope wall portion is represented by D and the diameter of the blade wheel is represented by d, 1.02<D/d<1.03 may be satisfied. When the height from the air suction opening to the position of a blade out of blades of the blade wheel which is nearest to the air suction opening is represented by hL, 0.24≦hL/h≦0.4 may be satisfied.
Furthermore, when the height from the air suction opening to the position of a blade out of blades of the blade wheel which is nearest to the air blow-out opening is represented by hZ, 0.875≦hZ/H≦0.925 may be satisfied. The axial-flow air blower may be a propeller fan. The blade wheel of the propeller fan may be disposed so as to be perfectly overlapped with the bell mouth in side view.
According to a second aspect of the present invention, an air conditioner includes an axial-flow air blower having a blade wheel for blowing air to a heat exchanger and a bell mouth that is provided around the blade wheel of the air blower and guides air from an air suction side of the blade wheel to an air blow-out side of the blade wheel, wherein the bell mouth has an air blow-out wall portion that intercommunicates with an air blow-out opening and extends substantially along an axial direction of the blade wheel, and a slope wall portion that intercommunicates with the air blow-out wall portion and slopes to an air suction opening so as to expand in diameter, and when the overall height of the bell-mouth is represented by H, the height of the slope wall portion is represented by h and a slope angle of the slope wall portion is represented by β, 0.33≦h/H≦0.42 and 60°≦β≦70° are satisfied.
According to the present invention, the bell mouth is configured so as to satisfy 0.33≦h/H≦0.42 and 60°≦β≦70°, whereby the reduction of the rotational number and the reduction of the driving force of the air blower can be satisfied at the same time with keeping the air flow amount equal.
A preferred embodiment according to the present invention will be described with reference to the accompanying drawings.
An air conditioner according to an embodiment comprises an outdoor unit 10 and an indoor unit (not shown), and makes refrigerant flow through a refrigerant circuit connected through a refrigerant pipe to perform cooling operation or heating operation. The outdoor unit 10 is disposed outdoors to heat-exchange with outdoor air so that refrigerant is condensed and heat is radiated to the outdoor air under cooling operation and also refrigerant is vaporized and take in heat from the outdoor air under heating operation. UP-and-down and right-and-left directions described below correspond to directions when the outdoor unit 10 is viewed from the front side thereof under the state that the outdoor unit 10 is installed.
As shown in
As shown in
A bell mouth 25 for guiding air at the air suction side of the propeller fan 24 to the air blow-out side of the propeller fan 24 is provided around the propeller fan 24, and the air blow-out opening 25A of the bell mouth 25 is covered by a fan guard (not shown) for preventing a human body or the like from coming into contact with the propeller fan 24. A face panel (not shown) is provided around the bell mouth 25 through a heat insulating member 26 such as foamed polystyrene.
When the propeller fan 24 is rotated by the fan motor 23, outdoor air is sucked into the unit case 11 from the surrounding of the outdoor unit 10, specifically, from the left, back and right sides of the unit case 11 excluding the front side of the unit case 11 as indicated by arrows X in
A compressor (not shown), an accumulator 31, an oil separator 32 and a receiver tank 33 which constitute a part of the refrigerant circuit are provided on the bottom plate 12 in the unit case 11, and refrigerant circuit constituting parts such as valve members such as a four-way valve (not shown), an expansion valve (not shown), etc. are mounted in the unit case 11 so as to be connected to one another through pipes. One end sides of the pipes for the refrigerant circuit constituting parts are connected to the indoor unit through the heat exchanger 21, and the other end sides of the pipes for the refrigerant circuit constituting parts are connected to the indoor unit, thereby constructing the refrigerant circuit in which refrigerant is circulated.
In this construction, the compressor is disposed at the front side of the unit case 11, and an electrical component box 34 in which various kinds of electrical component units such as a control board, etc. for controlling the air conditioner are arranged is disposed at the upper space of the compressor. Therefore, by detaching the front panel 15, a worker can easily perform a maintenance work for parts in the unit case 11. Reference numeral 35 represents a cover plate which is provided at the upper side of the compressor and prevents rain drops from directly impinging against the compressor.
Next, the construction of the bell mouth will be described.
The bell mouth 25 is formed by resin molding and thus it can be configured to be light in weight and have a desired shape. As shown in
The air blow-out wall portion 40 guides air blown out by the propeller fan 24 to the air blow-out opening 25A, and an angle α with respect to the plane of the air blow-out opening 25A is set to a right angle or an angle which is slightly smaller than the right angle (in this embodiment, the angle α=89°). Furthermore, the upper end portion of the air blow-out wall portion 40 (the end portion at the air blow-out opening side) is outwardly and annually bent to have a predetermined radius of curvature, and suppresses resistance to air flow when air is blown out.
Furthermore, the slope wall portion 41 smoothly feed air in the unit case 11 into the bell mouth 25 when the propeller fan 24 is operated, and it is integrally joined to the air blow-out wall portion 40 by a joint portion 42 as shown in
The propeller fan 24 has a hub 45 fixed to the motor shaft of a fan motor 23 (
The inventors of this application has performed a simulation to derive shape factors for the bell mouth 25 which can simultaneously satisfy both reduction of the rotational number of the propeller fan 24 and reduction of the load of the fan motor 23 at the same operating point of the air blower 22. Here, the same operating point of the air blower 22 means an operating condition that the air flow amount Q (m3/min) and the static pressure (mmAq) are equal. In
In
According to this simulation, it has been found that a bell mouth 25 designed in the neighborhood of the condition that h/H=0.33 (filled circles, filled rectangles) and the slope angle β=60° has the minimum rotational number of the propeller fan 24 and the minimum load of the fan motor 23 and thus has highest performance.
In a range where the slope angle β is larger than 70°, with respect to all bell mouths satisfying 0.20≦h/H≦0.67, the motor load and the rotational number of the propeller fan 24 trend to increase as the slope angle increases. On the other hand, in a range where the slope angle β is not more than 70°, with respect to a bell mouth satisfying h/H=0.67, the motor load and the rotational number are extremely high values.
When considered from the viewpoint of the motor load, with respect to bell mouths satisfying h/H−0.20, 0.33, the motor load has a local minimum point in the neighborhood of the slope angle β of 60°, and the motor load increases even when the slope angle β is smaller and larger than 60°. Here, the bell mouth satisfying h/H=0.20 has the remarkably largest value at the slope angle β=70. With respect to bell mouths satisfying h/H=0.42, 0.50, the motor load decreases when the slope angle β ranges from 50° to 60°, and it is equal to a substantially fixed value when the slope angle β ranges from 60° to 70°.
Furthermore, when considered from the viewpoint of the rotational number, with respect to a bell mouth satisfying h/H=0.50, it trends to decrease when the slope angle β ranges from 50° to 70°. With respect to a bell mouth satisfying h/H=0.42, it decreases when the slope angle β ranges from 50° to 60°, and it is equal to a substantially fixed value when the slope angle β ranges from 60° to 70°. With respect to a bell mouth satisfying h/H=0.3, the rotational number has a local minimum point in the neighborhood of the slope angle β of 60°, and the rotational number increases even when the slope angle β is smaller and larger than 60°. With respect to a bell mouth satisfying h/H=0.20, it trends to be substantially constant when the slope angle β ranges from 50° to 60°, but increase when the slope angle β ranges from 60° to 70°.
In order to reduce the rotational number of the propeller fan 24 and the load of the fan motor 23, it is found from this simulation that it is desirable to set 0.33≦h/H≦0.42 and 60°≦β≦70°.
As described above, when the bell mouth of this embodiment is configured to satisfy 0.33≦h/H≦0.42 and 60°≦β≦70°, it has been found that the bell mouth of this embodiment can satisfy both the reduction of the rotational number of the propeller fan 24 and the reduction of the motor load at the same time with keeping the same air flow amount.
As shown in
Accordingly, it is desirable from the simulation result that the propeller fan 24 is disposed so as to satisfy the range of 0.24≦hL/h≦0.40, whereby the rotational number of the propeller fan 24 and the motor load can be further reduced.
Accordingly, it is desirable from this simulation result that the propeller fan 24 is disposed so as to satisfy the range of 0.866≦hZ/H≦0.933, and further the propeller fan 24 is disposed so as to satisfy the range of 0.875≦hZ/H≦0.925. Accordingly, the rotational number of the propeller fan 24 and the motor load can be further reduced.
As described above, the bell mouth of this embodiment is configured so as to satisfy 0.33≦h/H≦0.42 and 60°≦β≦70°, the diameter D of the opening of the joint portion 42 of the bell mouth 25 is set to satisfy 1.02<D/d<1.03, and the propeller fan 24 is disposed in the bell mouth so as to satisfy 0.24≦hL/h≦0.40 and 0.866≦hZ/H≦0.933, whereby both the reduction of the rotational number of the propeller fan 24 and the reduction of the motor load can be satisfied at the same time with keeping the same air flow amount.
According to this embodiment, the propeller fan 24 is disposed so as to be perfectly overlapped with the bell mouth 25 in side view. Therefore, the area where the propeller fan 24 operates is covered by the bell mouth 25, whereby all the air blown by the propeller fan 24 can be guided by the bell mouth 25, and the air flow amount of the propeller fan 24 can be enhanced.
Claims
1. A bell-mouth structure of an air blower that is provided around a blade wheel of an axial-flow air blower and guides air from an air suction side of the blade wheel to an air blow-out side of the blade wheel, comprising:
- an air blow-out wall portion that intercommunicates with an air blow-out opening and extends substantially along an axial direction of the blade wheel; and
- a slope wall portion that intercommunicates with the air blow-out wall portion and slopes to an air suction opening so as to expand in diameter, wherein when the overall height of the bell-mouth is represented by H, the height of the slope wall portion is represented by h and a slope angle of the slope wall portion is represented by β, the bell mouth structure is configured so as to satisfy 0.33≦h/H≦0.42 and 60°≦β≦70°.
2. The bell mouth structure according to claim 1, wherein when the diameter of an opening of a connecting portion between the air blow-out wall portion and the slope wall portion is represented by D and the diameter of the blade wheel is represented by d, 1.02<D/d<1.03 is satisfied.
3. The bell mouth structure according to claim 1, wherein when the height from the air suction opening to the position of a blade out of blades of the blade wheel which is nearest to the air suction opening is represented by hL, 0.24≦hL/h≦0.4 is satisfied.
4. The bell mouth structure according to claim 1, wherein when the height from the air suction opening to a position of a blade out of blades of the blade wheel which is nearest to the air blow-out opening is represented by hZ, 0.875≦hZ/H≦0.925 is satisfied.
5. The bell mouth structure according to claim 1, wherein the axial-flow air blower is a propeller fan.
6. The bell mouth structure according to claim 5, wherein the blade wheel of the propeller fan is disposed so as to be perfectly overlapped with the bell mouth in side view.
7. An air conditioner comprising:
- a heat exchanger;
- an axial-flow air blower having a blade wheel for blowing air to the heat exchanger; and
- a bell mouth that is provided around the blade wheel of the air blower and guides air from an air suction side of the blade wheel to an air blow-out side, wherein the bell mouth has an air blow-out wall portion that intercommunicates with an air blow-out opening and extends substantially along an axial direction of the blade wheel, and a slope wall portion that intercommunicates with the air blow-out wall portion and slopes to an air suction opening so as to expand in diameter, and when the overall height of the bell-mouth is represented by H, the height of the slope wall portion is represented by h and a slope angle of the slope wall portion is represented by β, the bell mouth is configured so as to satisfy 0.33≦h/H≦0.42 and 60°≦β≦70°.
Type: Application
Filed: Nov 23, 2010
Publication Date: Jun 2, 2011
Applicant: SANYO ELECTRIC CO., LTD. (Osaka)
Inventors: Abastari (Oura-gun), Takayuki Masukawa (Ota-shi), Hirofumi Yanagi (Kumagaya-shi), Takeshi Nakamura (Oura-gun)
Application Number: 12/952,726
International Classification: F28F 13/00 (20060101); F01D 1/04 (20060101);