CROSS-FLOW FAN AND AIR CONDITIONER EQUIPPED WITH SAME
A crossflow fan includes an impeller formed by plate-like blades 42. Each blade 42 is inclined such that the outer edge 42a is located on the leading side of the inner edge 42d with respect to the rotation direction of the impeller 41. The face of each blade 42 that is located on the leading side of the rotation direction forms a positive pressure surface 42p, and a face located on the trailing side forms a negative pressure surface 42q. Notches 42b are formed at the outer edge 42a of the blade 42. The notches 42b are arranged at predetermined intervals along the rotation axis of the impeller. The bottom 42y of the notch 42b is connected to the positive pressure surface 42p at a positive pressure corner 42n and connected to the negative pressure surface 42q at a negative pressure corner 42m. The positive pressure corner 42n and the negative pressure corner 42m are both rounded.
The present invention relates to a crossflow fan and an air conditioner having the crossflow fan.
BACKGROUND ARTCrossflow fans are known as air blowers as used in an indoor unit of a wall-mounted air conditioner.
In the impeller of such a crossflow fan, air passing through the blades of the impeller generates noise. In an attempt to reduce such noise with a simple structure, crossflow fans have been proposed that have a plurality of notches formed at an edge of each blade (for example, see Patent Document 1).
Problems that the Invention is to Solve
As described in Patent Document 1, a simple structure where notches are formed at an edge of each blade can effectively reduce noise. However, when employed, this structure increases air resistance against rotation of the impeller 241. Specifically, when notches 242b are formed at the outer edge 242a of each blade 242 as shown in
Accordingly, it is an objective of the present invention to provide a crossflow fan that prevents the power output required from an electric motor driving the crossflow fan from being increased, and an air conditioner having the crossflow fan.
Means for Solving the ProblemsTo achieve the foregoing objective and in accordance with one aspect of the present invention, a crossflow fan is provided that includes an impeller having a plurality of support plates located on a rotation axis of the impeller and a plurality of plate-like blades provided at peripheral portions of the support plates. The blades extend parallel to the rotation axis. Each blade is inclined such that its outer edge is located on the leading side of its inner edge with respect to the rotation direction of the impeller. One of the faces of each blade that is on the leading side of the rotation direction of the impeller forms a positive pressure surface. The face on the trailing side of the rotation direction forms a negative pressure surface. A plurality of notches are formed at the outer edge of each blade. The notches are arranged at predetermined intervals along the rotation axis of the impeller. At least one of a positive pressure corner and a negative pressure corner, which connect the bottom of each notch with the positive pressure surface and the negative pressure surface, respectively, is rounded.
Since the notches are formed in the outer edge of the blade, noise is effectively reduced with a simple structure. At least one of the positive pressure corner and negative pressure corner, which connect the bottom of the notch with the positive pressure surface and the negative pressure surface, respectively, is rounded. Therefore, air that flows into the notches from the outer side of the blade is allowed to flow smoothly into the impeller along the negative pressure surface and the positive pressure surface. This reduces the collision loss generated when air flows in from outside of the blade. As a result, required increased power output from the electric motor driving the crossflow fan caused by the formation of the notches in the blades can be reduced. In the above, the predetermined intervals may be the same intervals or may vary according to the position in the longitudinal direction of the blade.
In accordance with the present invention, the negative pressure corner, which connects the bottom of each notch with the negative pressure surface, may be rounded.
Also, in accordance with the present invention, the positive pressure corner, which connects the bottom of each notch with the positive pressure surface, may be rounded.
To achieve the foregoing objective and in accordance with one aspect of the present invention, a crossflow fan is provided that includes an impeller having a plurality of support plates located on a rotation axis of the impeller and a plurality of plate-like blades provided at peripheral portions of the support plates. The blades extend parallel to the rotation axis. Each blade is inclined such that its outer edge is located on the leading side of its inner edge with respect to the rotation direction of the impeller. One of the faces of each blade that is on the leading side of the rotation direction of the impeller forms a positive pressure surface. The face on the trailing side of the rotation direction forms a negative pressure surface. A plurality of notches are formed at the outer edge of each blade. The notches are arranged at predetermined intervals along the rotation axis of the impeller. The bottom of each notch is formed as a smooth curved surface that protrudes as a whole outward of the impeller.
Since the notches are formed in the outer edge of the blade, noise is effectively reduced with a simple structure. Further, since the bottom of each notch is formed to be a smooth curved surface that protrudes as a whole toward the outer circumference of the impeller, air that flows into the notches from the outer side of the blade is allowed to flow smoothly into the impeller along the negative pressure surface and the positive pressure surface. This reduces the collision loss generated when air flows into the notches from outside of the blade. As a result, required increased power output from the electric motor driving the crossflow fan can be reduced. In the above, the predetermined intervals may be the same intervals or may vary according to the position in the longitudinal direction of the blade.
In the present invention, the notches are preferably V-shaped as viewed from the negative pressure surface and the pressure surface of the blade,
According to this configuration, a greater pressure receiving area of the blade is ensured compared to a case where the notch has a rectangular shape.
Further, the present invention also provides an air conditioner having a crossflow fan having the above described configuration.
EFFECTS OF THE INVENTIONAccording to the present invention, since the notches are formed in the outer edge of the blade, noise is effectively reduced with a simple structure. At least one of the positive pressure corner and negative pressure corner, which connects the bottom of the notch with the positive pressure surface and the negative pressure surface, respectively, is rounded. Therefore, air that flows into the notches from the outer side of the blade is allowed to flow smoothly into the impeller along the negative pressure surface and the positive pressure surface. This reduces the collision loss generated when air flows in from outside of the blade. As a result, required increased power output from the electric motor driving the crossflow fan caused by the formation of the notches in the blades can be reduced.
One embodiment of the present invention will now be described with reference to
As shown in
Air inlet ports 21 are provided in upper and front face of the main casing 2. An air outlet port 22 is provided in a lower face of the main casing 2. At the air outlet port 22, vertical flaps 23 and a horizontal flap 24 for adjusting the direction of air discharged from the air outlet port 22 are provided.
A guide portion 25 is formed in the main casing 2 at a position in the vicinity of the outlet region M of the crossflow fan 4. The guide portion 25 defines the passage of air discharged by the crossflow fan 4. A backflow preventing tongue 26 is formed at the air outlet port 22. The backflow preventing tongue 26 separates the outlet region M and the inlet region N from each other, thereby preventing discharged air from flowing back.
The heat exchanger 3 is located between the air inlet port 21 and the impeller 41, and formed by a front heat exchanging section 3a and a back heat exchanging section 3b. The front heat exchanging section 3a is located in the main casing 2 near the front face. The back heat exchanging section 3b is continuously formed at the top of the front heat exchanging section 3a, and is located in the main casing 2 near the back face.
According to the above shown structure, when the impeller 41 of the crossflow fan 4 is driven by the electric motor, air in the room is drawn in to the main casing 2 through the inlet port 21. The air is cooled or heated by passing through the heat exchanger 3, and is discharged into the room through the air outlet port 22. Accordingly, conditioned air is delivered to the room.
As shown in
The structure of each blade 42 will be described with reference to
Notches 42b are formed at the outer edge 42a of the blade 42. The notches 42b are arranged at predetermined intervals along the rotation axis A1 of the impeller 41. The notches 42b are V-shaped when viewed from the negative pressure surface 42q and the positive pressure surface 42p of the blade 42. A basic shape section 42c is formed between each adjacent pair of the notches 42b. The basic shape sections 42c form the curved basic shape of the blade 42. The width of the space between adjacent notches 42b may be constant or may vary. For example, as shown in
The notches 42b may have the same size, but may have different sizes depending on position on the rotation axis A1. In the present embodiment, notches 42b at each end 6a of the blade 42 in the rotation axis A1 have a smaller size than notches 42b at the center 6b of the blade 42. This ensures a sufficient pressure receiving area at each end 6a of the blade 42.
As described above, the notches 42b formed at the outer edge 42a of the blade 42 at predetermined intervals, and the basic shape sections 42c are each formed between adjacent notches 42b as shown in
The notches 42b are V-shaped when viewed from the negative pressure surface 42q and the positive pressure surface 42p of the blade 42. Thus, compared to a case where notches 42b have rectangular shapes, the pressure receiving area of the blade 42 is enlarged.
More specifically, the bottom 42y of each notch 42b, which extends perpendicularly to the negative pressure surface 42q of the blade 42, and the negative pressure surface 42q are smoothly connected to each other by the negative pressure corner 42m. The bottom 42y of each notch 42b, which extends perpendicularly to the positive pressure surface 42p of the blade 42, and the positive pressure surface 42p are smoothly connected to each other by the positive pressure corner 42n. Therefore, the length of the bottom 42y, which extends perpendicularly to the positive pressure surface 42p and the negative pressure surface 42q, is less than that of the bottom 242y of the prior art notch 242b (see
As described above, the negative pressure corner 42m and the positive pressure corner 42n are rounded to form smooth and curved surfaces. This allows the air flow X that flows into the notches 42b from outside of the blade 42 to flow smoothly along the negative pressure surface 42q and into the impeller 41. As a result, the collision loss generated when the air flow X flows from outside of the blade 42 into the notches 42b is reduced.
The crossflow fan 4 according to the present embodiment has the following advantages.
(1) The positive pressure corner 42n and the negative pressure corner 42m, which connect the bottom 42y of the notch 42b to the positive pressure surface 42p and the negative pressure surface 42q, respectively, are rounded to have a smooth and curved surface. This allows the air flow X that flows into the notches 42b from outside of the blade 42 to flow smoothly into the impeller 41 along the negative pressure surface 42q and the positive pressure surface 42p. This reduces the collision loss generated when air flow X flows from outside of the blade 42 to the notches 42b. As a result, the required increase in power output from the electric motor driving the crossflow fan 4 caused by the formation of the notches in the blades 42 can be reduced. Particularly, since the negative pressure corner 42m and the positive pressure corner 42n are both rounded in the present embodiment, the collision loss generated when the air flow X flows from outside of the blade 42 is reduced, and required increased power output from the electric motor driving the crossflow fan can be reduced.
(2) The notches 42b are V-shaped when viewed from the negative pressure surface 42q and the positive pressure surface 42p of the blade 42. Thus, a sufficient pressure receiving area for the blade 42 is ensured.
The air conditioner of the present embodiment has the crossflow fan 4, which achieves the advantages (1) and (2). The air conditioner therefore achieves the same advantages as the advantages (1) and (2).
The present invention is not limited to the above embodiment, but can be modified in various forms within the spirit of the present invention. The modifications are not excluded from the scope of the present invention. For example, the above embodiments may be modified as follows.
In the above embodiment, the negative pressure corner 42m and the positive pressure corner 42n are both rounded. Instead, only one of the negative pressure corner 42m and the positive pressure corner 42n may be rounded.
As shown in
In the above illustrated embodiments, the notches 42b are V-shaped when viewed from the negative pressure surface 42q and the positive pressure surface 42p of the blade 42. However, this configuration may be changed. For example, as shown in
Claims
1. A crossflow fan comprising an impeller having a plurality of support plates located on a rotation axis of the impeller and a plurality of plate-like blades provided at peripheral portions of the support plates, the blades extending parallel to the rotation axis, each blade being inclined such that its outer edge is located on the leading side of its inner edge with respect to the rotation direction of the impeller, one of the faces of each blade that is on the leading side of the rotation direction of the impeller forms a positive pressure surface, the face on the trailing side of the rotation direction forms a negative pressure surface,
- the crossflow fan being characterized in that a plurality of notches are formed at the outer edge of each blade, the notches being arranged at predetermined intervals along the rotation axis of the impeller,
- wherein at least one of a positive pressure corner and a negative pressure corner, which connect the bottom of each notch with the positive pressure surface and the negative pressure surface, respectively, is rounded.
2. The crossflow fan according to claim 1, characterized in that the negative pressure corner, which connects the bottom of each notch with the negative pressure surface, is rounded.
3. The crossflow fan according to claim 1 or 2, characterized in that the positive pressure corner, which connects the bottom of each notch with the positive pressure surface, is rounded.
4. A crossflow fan comprising an impeller having a plurality of support plates located on a rotation axis of the impeller and a plurality of plate-like blades provided at peripheral portions of the support plates, the blades extending parallel to the rotation axis, each blade being inclined such that its outer edge is located on the leading side of its inner edge with respect to the rotation direction of the impeller, one of the faces of each blade that is on the leading side of the rotation direction of the impeller forms a positive pressure surface, the face on the trailing side of the rotation direction forms a negative pressure surface,
- the crossflow fan being characterized in that a plurality of notches are formed at the outer edge of each blade, the notches being arranged at predetermined intervals along the rotation axis of the impeller,
- wherein the bottom of each notch is formed as a smooth curved surface that protrudes as a whole outward of the impeller.
5. The crossflow fan according to claim 1, characterized in that each notch is V-shaped as viewed from the negative pressure surface and the pressure surface of the blade.
6. An air conditioner characterized by the crossflow fan according to claim 1.
Type: Application
Filed: Apr 30, 2009
Publication Date: Feb 10, 2011
Inventors: Hironobu Teraoka (Sakai-shi), Shimei Tei (Sakai-shi)
Application Number: 12/937,833
International Classification: F04D 29/38 (20060101);