JP2014080970A - Propeller fan and air conditioner including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a propeller fan capable of reducing noise.SOLUTION: A propeller fan 4 includes a blade 12, and the blade 12 includes a shape that has a peak of an outlet angle θ of a rear edge part 15 in an outside area 12B outside a radial direction with respect to a representative square mean radius position Rr and has a peak of the outlet angle θ of the rear edge part 15 in an inside area 12A inside the radial direction with respect to the representative square mean radius position Rr.

Description

  The present invention relates to a propeller fan and an air conditioner including the same.

  Conventionally, propeller fans used in air conditioners and the like are known. When the propeller fan rotates, in the vicinity of the outer peripheral part of the blade, an air flow (leakage flow) is generated from the pressure surface side with high pressure to the negative pressure surface side with low pressure, and this air flow causes the air flow near the outer peripheral part of the blade. A vortex (blade tip vortex) is formed. Such blade tip vortices cause noise.

  In the propeller fan of Patent Document 1, attempts have been made to stabilize the blade tip vortex by providing a bent portion on the outer peripheral portion of the blade to reduce noise.

Japanese translation of PCT publication No. 2003-072948

  However, there is a case where a sufficient noise reduction effect cannot always be obtained just by providing a bent portion on the outer peripheral portion of the blade as in Patent Document 1.

  An object of the present invention is to provide a propeller fan capable of reducing noise.

  (1) The propeller fan of the present invention includes a blade (12), and the blade (12) has a trailing edge (15) in an outer region (12B) radially outside the representative root mean square position (Rr). A shape having a peak of the outlet angle (θ) of the trailing edge (15) in the inner region (12A) radially inward of the representative root mean square radial position (Rr). Is provided.

  In this configuration, the representative square mean radius position (Rr) that divides the flow path area of the propeller fan into two equal parts on the radially inner side and the radially outer side is used as a reference, and the outer region (12B) occupying half of the flow path area; Noise can be effectively reduced by providing each of the inner regions (12A) occupying the remaining half of the flow path area with a function of guiding air in the circumferential direction. Specifically, it is as follows.

  In general, when the propeller fan rotates, the air flowing along the pressure surface tends to flow to the outer peripheral side (blade end side) due to the influence of the pressure gradient and centrifugal force.

  Therefore, in this configuration, by adopting a blade shape in which the peak of the exit angle (θ) of the rear edge (15) exists in the outer region (12B), the rear edge (15) in the outer region (12B) Since the work of the fan increases, the effect of guiding the air flowing along the pressure surface (21) of the outer region (12B) in the circumferential direction can be enhanced. Further, in this configuration, by adopting a blade shape in which the peak of the exit angle (θ) of the rear edge (15) also exists in the inner area (12A), the rear edge (15) of the inner area (12A) is adopted. ) Also increases the work amount of the fan, so that the effect of guiding the air flowing along the pressure surface (21) of the inner region (12A) in the circumferential direction can be enhanced. Thereby, since it can suppress that an airflow flows into the outer peripheral part (16) side (blade end side), the air flow (around the pressure surface (21) side to the negative pressure surface (22) side in the vicinity of an outer peripheral part (16) ( Increase in leakage flow is suppressed. As a result, the generation of blade tip vortices due to leakage flow is suppressed, so that noise can be reduced. In addition, a decrease in fan performance is suppressed by suppressing an increase in leakage flow.

  Further, as described above, in the propeller fan having the above configuration, the air that has flowed into the pressure surface (21) from the front edge portion (14) of the blade (12) is directed to the outer peripheral portion (16) side (blade end side). The flow to the outer side in the radial direction is suppressed, and the flow in the circumferential direction becomes dominant. As a result, the height of the hub (11) (the thickness of the hub in the direction of the rotation axis (A0)) can be reduced, so that the propeller fan can be reduced in weight. Specifically, it is as follows.

  In the propeller fan, when the height of the hub is reduced, it is necessary to reduce the blade height at the inner peripheral portion of the blade connected to the outer peripheral surface of the hub (joint portion of the blade with the hub). The blade height is a height difference (a height difference in the rotation axis direction) between one end (end on the front edge side) and the other end (end on the rear edge side) of the camber line in the joint. When the blade height is reduced, the work amount of the blades near the joint (head rise) is reduced. Therefore, the air that has flowed into the pressure surface from the front edge portion has a large work amount on the blade end side (the head rises greatly). It tends to flow radially outward (to the blade tip side). Therefore, if the height of the hub is reduced in the conventional propeller fan, the circumferential flow cannot be made dominant. In order to obtain the work of the blades near the joint (head rise), by expanding the fan-shaped blade extending from the joint to the blade tip, that is, by increasing the chord length near the joint. A means of increasing the area of the pressure surface in the vicinity of the joint (increasing the integral value) can be considered. However, if this means is adopted, the weight of the blades increases, and thus the propeller fan cannot be reduced in weight.

  On the other hand, in the propeller fan of the present invention, as described above, the outer region (12B) has a peak of the exit angle (θ) of the rear edge (15) and the inner region (12A) also has the rear edge (15). By adopting the blade (12) having a shape having a peak of the outlet angle (θ), the flow of air in the circumferential direction can be made dominant. Therefore, in the propeller fan of the present invention, the height of the hub (11) can be made smaller than the conventional one and the weight of the propeller fan can be reduced while maintaining the state where the air flow in the circumferential direction is dominant.

  In the propeller fan of the present invention, the exit angle (θ) of the peak position in the outer region (12B) and the exit angle (θ) of the peak position in the inner region (12A) may be the same value. Well, it may be a different value. When the value is different, the exit angle (θ) of the peak position in the outer region (12B) may be larger than the exit angle (θ) of the peak position in the inner region (12A), The value may be smaller than the exit angle (θ) of the peak position in the inner region (12A).

  (2) In the propeller fan, the maximum value of the radius of curvature of the pressure surface (21) in the inner region (12A) is larger than the maximum value of the radius of curvature of the pressure surface (21) in the outer region (12B). Is preferred.

  In this configuration, the inner region (12A) has a smaller radius of curvature than the outer region (12B) and has a more planar shape, so that the cross-sectional area of the blade (12) is reduced particularly in the inner region (12A). can do. Thereby, weight reduction of a blade | wing (12) can be achieved and the increase in volume can be suppressed.

  (3) In the propeller fan, the pressure surface (21) in the inner region (12A) and the pressure surface (21) in the outer region (12B) preferably include a concave curved surface.

  In this configuration, the pressure surface (21) of the inner region (12A) and the pressure surface of the outer region (12B) both include concave curved surfaces, so that air flowing along the pressure surface in each region is guided in the circumferential direction. The effect to do can be further enhanced.

  In addition, when both the above configurations (2) and (3) are provided, the following effects can be obtained. That is, in this case, the maximum value of the pressure surface (21) in the outer region (12B) is smaller than the maximum value of the pressure surface (21) in the inner region (12A), and the pressure surface of these regions (12A, 12B). A configuration including a concave curved surface is adopted. Since the pressure gradient between the pressure surface (21) and the suction surface (22) is large in the outer region (12B) close to the outer peripheral portion (16), the pressure of the outer region (12B) is set by setting the radius of curvature small. The effect of guiding the air flowing along the surface (21) in the circumferential direction can be further enhanced. As a result, the generation of leakage flow is further suppressed as a whole of the pressure surface (21).

  (4) In the propeller fan, the inner region (12A) and the outer region (12B) are each provided with a concave curved surface, and there is also a peak of the exit angle (θ). A form can be illustrated.

  (5) In the propeller fan, the rear edge (15) of the blade (12) is provided with a recess (19) recessed toward the front edge in a region including the representative mean square radial position (Rr). It is preferable.

  In this configuration, since the concave portion (19) is provided in the region including the representative root mean square radius position (Rr) of the trailing edge portion (15) where the pressure rise is the largest, the pressure rise is near the concave portion (19). Is reduced. As a result, the air flowing from the front edge portion (14) to the rear edge portion (15) side avoids the representative root mean square radial position (Rr) in the vicinity of the rear edge portion (15), so that the hub (11) side is avoided. Therefore, the effect of guiding the air flow in the circumferential direction can be further enhanced.

  (6) The air conditioner of the present invention includes the propeller fan (4). Therefore, noise is reduced in this air conditioner.

  According to the present invention, it is possible to provide a propeller fan capable of reducing noise.

It is sectional drawing which shows schematic structure of the outdoor unit of the air conditioner which concerns on one Embodiment of this invention. It is a front view showing a propeller fan concerning a 1st embodiment of the present invention. It is a graph which shows the relationship between the radial position in the rear edge part of a propeller fan, and an exit angle. (A) is the front view which shows the radial position corresponding to five radial position A1-A5 in the graph of FIG. 3 in the blade | wing of the propeller fan of 1st Embodiment, (B) is the propeller fan of a reference example. 5 is a front view showing radial positions corresponding to five radial positions A1-A5 in the graph of FIG. It is a figure for demonstrating the representative square mean radius position in a propeller fan. It is sectional drawing which cut | disconnected the blade | wing along the circumferential direction. (A), (B) is the VIIA-VIIA sectional view taken on the line of FIG. 4 (A), (C) is the VIIC-VIIC sectional view taken on the line of FIG. 4 (B). (A) is a perspective view which shows the flow of the air in the propeller fan which concerns on 1st Embodiment, (B) is the figure which showed the flow of the air roughly. (A) is a perspective view which shows the flow of the air in the propeller fan which concerns on a reference example, (B) is the figure which showed the flow of the air roughly. (A), (B) is the graph which compared the characteristic of the propeller fan which concerns on 1st Embodiment, and the characteristic of the propeller fan which concerns on a reference example. (A) shows the relationship between air volume and blowing sound, and (B) shows the relationship between air volume and fan motor input. (A) is a front view which shows a part of propeller fan which concerns on 2nd Embodiment of this invention, (B) is the XIB-XIB sectional view taken on the line of (A).

<Overall structure of air conditioner>
Hereinafter, a propeller fan and an air conditioner including the propeller fan according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic structure of an outdoor unit 1 for an air conditioner according to an embodiment of the present invention. The air conditioner includes the outdoor unit 1 shown in FIG. 1 and an indoor unit (not shown). The outdoor unit 1 includes an outdoor heat exchanger 3, a propeller fan 4, a motor 5, a compressor (not shown), and the like, which are accommodated in a casing 2. The indoor unit includes an unillustrated expansion mechanism, an indoor heat exchanger, and the like. The compressor, the outdoor heat exchanger 3, the expansion mechanism, the indoor heat exchanger, and an unillustrated refrigerant pipe connecting them constitute the refrigerant circuit of the air conditioner.

  In the outdoor unit 1 shown in FIG. 1, the outdoor heat exchanger 3 is provided on the back side of the casing 2, and the air outlet 7 is provided on the front side of the casing 2, but is not limited thereto. In the outdoor unit 1, the blower outlet 7 may be provided in the upper part of the casing 2, for example. The blower outlet 7 is provided with a fan guard 7a having a grill structure.

  The propeller fan 4 is disposed inside the air outlet 7 of the casing 2. The propeller fan 4 is connected to the shaft 5a of the motor 5 and is rotated about the rotation axis A0 by the motor 5. In the present embodiment, the rotation axis A0 of the propeller fan 4 faces in the front-rear direction (horizontal direction), but is not limited to this. The rotation axis A0 may be directed in a direction inclined with respect to the horizontal direction, for example. For example, in the outdoor unit 1 in which the air outlet 7 is provided in the upper part of the casing 2, the rotation axis A0 of the propeller fan 4 may face the up-down direction (vertical direction).

  A bell mouth 6 surrounding the outer periphery of the propeller fan 4 is provided in the casing 2. The bell mouth 6 is provided between a region X (suction region X) on the upstream side of the air flow with respect to the propeller fan 4 and a region Y (outlet region Y) on the downstream side of the air flow with respect to the propeller fan 4. It has been. The bell mouth 6 is an annular member along the periphery of the propeller fan 4, and guides the air that has passed through the outdoor heat exchanger 3 to the air outlet 7. The bell mouth 6 is arranged with a small gap between it and the propeller fan 4 so as not to contact the propeller fan 4.

  The propeller fan 4, the motor 5 and the bell mouth 6 constitute an axial flow fan 8. When the motor 5 of the axial flow fan 8 is driven to rotate the propeller fan 4, a pressure difference is generated between the suction area X and the blowing area Y, and an air flow from the suction area X toward the blowing area Y is formed.

<First Embodiment>
FIG. 2 is a front view showing the propeller fan 4 according to the first embodiment of the present invention. The propeller fan 4 includes a hub 11 and a plurality of blades 12. In the present embodiment, the propeller fan 4 includes the three blades 12, but is not limited thereto, and may include two blades 12 or four or more blades 12. In the present embodiment, the hub 11 and the plurality of blades 12 are formed by integral molding, but the present invention is not limited to this, and may be formed by joining a plurality of separately molded components.

  The hub 11 usually has a shape such as a columnar shape or a truncated cone shape, but is not limited thereto. The hub 11 has an outer peripheral surface 11a to which a plurality of blades 12 are connected. The plurality of blades 12 are arranged at equal intervals along the outer peripheral surface 11 a of the hub 11. For example, in the case of the cylindrical hub 11, the outer diameter is substantially constant. However, in the case of the truncated cone-shaped hub 11, the outer diameter increases or decreases toward the rotation axis A <b> 0. Further, the hub 11 may have a shape such as a combination of a columnar shape and a truncated cone shape, or may have another shape. The rotation axis A0 of the propeller fan 4 is located at the center of the hub 11.

  Each blade 12 is located on the radially inner side (hub 11 side) and connected to the hub 11, the front edge portion 14 positioned on the front side in the rotational direction D, and the rear side in the rotational direction D ( A rear edge portion 15 located on the opposite side to the rotation direction D and an outer peripheral portion 16 located on the radially outer side. Each blade 12 has a shape that is twisted so that the front edge portion 14 is located generally on the suction region X side as compared with the rear edge portion 15. Moreover, each blade | wing 12 has the pressure surface 21 located in the blower outlet 7 side (blowing area | region Y side), and the negative pressure surface 22 (refer FIG. 6) located in the other side (suction area | region X side).

  As shown in FIG. 2, the outer peripheral portion 16 includes a bent portion 17 in which an end portion of the blade 12 is bent to the suction surface 22 side (the suction region X side), and an outer peripheral edge constituting a radially outer edge of the blade 12. Part 18. The outer peripheral portion 16 is a region having a width from the bent portion 17 to the outer peripheral edge portion 18. By providing the bent portion 17, it is possible to suppress the generation of vortex in the vicinity of the outer peripheral portion 16 of each blade 12.

  The bent portion 17 extends from the front edge portion 14 (or the vicinity of the front edge portion 14) to the rear edge portion 15. In the present embodiment, the width of the outer peripheral portion 16 (the distance between the bent portion 17 and the outer peripheral edge portion 18) increases toward the rear edge portion 15, but is not limited thereto. Further, the bent portion 17 can be omitted. In this case, the outer peripheral portion 16 includes an outer peripheral edge portion 18.

(Rear edge exit angle)
Next, the exit angle θ of the trailing edge 15 which is a feature of the propeller fan 4 of the first embodiment will be described. In the graph of FIG. 3, the solid line indicates the relationship between the radial position and the exit angle θ at the trailing edge 15 of the propeller fan 4 of the first embodiment shown in FIGS. 2 and 4A, and the broken line indicates The relationship between the radial position in the rear edge part 115 of the propeller fan 104 of the reference example of FIG.4 (B), and exit angle | corner (theta) is shown.

  The propeller fan 104 of the reference example will be briefly described. The propeller fan 104 of the reference example includes a hub 111 and three blades 112. Each blade 112 has an inner peripheral portion 113, a front edge portion 114, a rear edge portion 115, and an outer peripheral portion 116 (bending portion 117, outer peripheral edge portion 118). Each blade 112 has a pressure surface 121 and a negative pressure surface 122 (see FIG. 7C).

  As shown in FIG. 3, a plurality of peaks of the exit angle θ exist at the rear edge portion 15 of each blade 12 of the propeller fan 4 of the first embodiment. Specifically, the rear edge portion 15 of each blade 12 is provided with two peaks of the exit angle θ, and one peak is located behind the outer region 12B radially outside the representative square mean radius position Rr. The other peak is provided at the edge 15 and is provided at the rear edge 15 of the inner region 12A on the radially inner side from the representative root mean square radial position Rr.

  In the present embodiment, the peak does not necessarily mean the maximum value of the exit angle. That is, in the graph as shown in FIG. 3, the exit angles corresponding to the vertices of the upwardly protruding broken line portions are all peaks. Therefore, there may be a plurality of peaks having different exit angles at the trailing edge 15 of one blade 12.

  On the other hand, only one peak of the exit angle θ exists at the trailing edge 15 of each blade 12 in the reference example shown in FIG. This peak is provided at the rear edge 115 of the outer region radially outside the representative mean square radius position Rr. In this reference example, the outlet angle θ of the trailing edge 115 is designed to gradually increase from the inner peripheral portion 113 toward the outer peripheral portion 116, and the peak of the outlet angle θ of the trailing edge 115 is a representative square. It is provided in an outer region (a position in the vicinity of the outer peripheral portion 116) on the outer side in the radial direction from the average radius position Rr.

  The representative root mean square radial position Rr is a radial position that divides the flow path area of the propeller fan 4 (104) into two equal parts on the center side (hub side) and the outer peripheral side. FIG. 5 is a diagram for explaining the representative root mean square radius position Rr in the propeller fan 4 (104). The representative mean square radius position Rr is calculated using the following equation (1) represented by the representative radius R of the blade 12 (112) and the representative radius r of the hub 11 (111).

Representative root mean square position Rr = ((R ² + r ² ) / 2) ^0.5 (1)
The representative radius R of the blade is obtained as follows.

  That is, the representative radius R of the blade is ½ of the outer diameter when the outer diameter of the blade is constant in the rotation axis direction.

  When the outer diameter of the blade is not constant in the rotation axis direction, the representative radius R of the blade is obtained as follows. That is, the representative radius R of the blade is an average value of the minimum blade radius R1 and the maximum blade radius R2 (R = (R1 + R2) / 2).

  The representative radius r of the hub is a value that is ½ of the outer diameter when the outer diameter of the hub is constant in the rotation axis direction.

  When the outer diameter of the hub is not constant in the direction of the rotation axis, for example, when the hub has a truncated cone shape, the representative radius r of the hub is obtained as follows.

  That is, the representative radius r of the hub is an average value of the minimum hub radius r1 and the maximum hub radius r2 (r = (r1 + r2) / 2).

  The five radial positions A1-A5 shown in FIG. 3 correspond to the radial positions A1-A5 shown in FIGS. For example, as shown in FIGS. 4A and 4B, the radial position A1 is a position where a circle with a radius A1 centering on the rotation axis A0 and the blade 12 (112) overlap when the propeller fan is viewed from the front. is there. Since the same applies to the radial positions A2-A5, the description thereof is omitted.

  In the first embodiment and the reference example of FIGS. 4A and 4B, the radial position A3 coincides with the representative mean square radial position Rr, but is not limited to this. Radial position A3 has the smallest exit angle θ3 between the two peaks. The radial positions A1 and A2 are located in the inner region 12A that is closer to the hub 11 than the radial position A3. The radial positions A4 and A5 are located in the outer region 12B on the outer peripheral portion 16 side than the radial position A3.

  6 is a cross-sectional view (for example, a cross-sectional view at the radial position A3 in FIG. 4) in which the blade 12 is cut along the circumferential direction. In the cross-sectional view shown in FIG. 6, the exit angle θ at the trailing edge 15 is an angle formed by a tangent line L3 that is in contact with the pressure surface 21 at the trailing edge 15 and a straight line L4 that is perpendicular to the rotation axis A0 of the propeller fan 4. .

  In the first embodiment, as shown in FIG. 3, the peak of the outlet angle θ in the inner region 12A, that is, the maximum value of the outlet angle θ in the inner region 12A is the outlet angle θ2 at the radial position A2 (first peak position). is there. The peak of the exit angle θ in the outer region 12B, that is, the maximum value of the exit angle θ in the outer region 12B is the exit angle θ4 at the radial position A4 (second peak position).

  The exit angle θ3 at the radial position A3 is smaller than the exit angles θ2 and θ4. In the present embodiment, the minimum value of the exit angle θ between the peak positions (between the radius position A2 and the radius position A4) is the exit angle θ3 at the representative mean square radius position Rr (radius position A3). It is not limited to. The minimum value of the exit angle θ between the peak positions may be the exit angle at a position shifted from the representative root mean square position Rr.

  In the present embodiment, the exit angle θ at the rear edge portion 15 gradually increases from the inner peripheral portion 13 to the radial position A2, and gradually decreases from the radial position A4 to the outer peripheral portion 16 (bending portion 17). Further, the exit angle θ at the trailing edge 15 gradually decreases from the radial position A2 to the radial position A3, and gradually increases from the radial position A3 to the radial position A4. That is, the exit angle θ at the rear edge portion 15 of the present embodiment changes in a substantially M shape as shown in FIG.

  A specific example of the difference between the exit angles θ2 and θ4 at the peak position and the exit angle θ3 that is the minimum value therebetween is as follows. That is, the difference between the exit angle θ2 and the exit angle θ3 can be set, for example, in the range of 0.5 to 10 degrees or in the range of 1 to 5 degrees. The difference between the exit angle θ4 and the exit angle θ3 can be set, for example, in the range of 0.5 degrees to 10 degrees or in the range of 1 degree to 5 degrees.

  In the example shown in FIG. 3 as an embodiment, the exit angle θ2 at the radial position A2 (first peak position) and the exit angle θ4 at the radial position A4 (second peak position) have the same value. It is not limited to this. The exit angle θ2 and the exit angle θ4 may be different from each other. Specifically, the exit angle θ2 may be larger than the exit angle θ4 or smaller than the exit angle θ4.

(Curvature radius of pressure surface)
Next, the curvature radius of the pressure surface 21, which is another feature of the propeller fan 4 of the first embodiment, will be described. 7A and 7B are cross-sectional views taken along line VIIA-VIIA in FIG. 7A and 7B are cross-sectional views when the propeller fan 4 of the first embodiment is cut along a plane including the rotation axis A0. FIG. 7C is a cross-sectional view taken along line VIIC-VIIC in FIG. FIG. 7C is a cross-sectional view of the propeller fan 104 of the reference example cut along a plane including the rotation axis A0.

  As shown in FIG. 7A, in the propeller fan 4 of the first embodiment, the pressure surface 21A (inner pressure surface 21A) in the inner region 12A includes a concave curved surface, and the pressure surface 21B (outer pressure) in the outer region 12B. The surface 21B) also includes a concave curved surface different from the concave curved surface. In the present embodiment, the outer pressure surface 21 </ b> B is a region between the representative root mean square radius position Rr and the bent portion 17 of the outer peripheral portion 16.

  The concave curved surface of the inner pressure surface 21A and the concave curved surface of the outer pressure surface 21B are adjacent to each other via the representative mean square radius position Rr. In other words, the concave curved surface of the inner pressure surface 21A and the concave curved surface of the outer pressure surface 21B are juxtaposed in the radial direction. As shown in FIG. 7A, the representative mean square radius position Rr to which these two concave curved surfaces are connected and the pressure surface 21C in the vicinity thereof are convex curved surfaces.

  The concave surface of the inner pressure surface 21A is formed along the circumferential direction from the front edge portion 14 to the rear edge portion 15, and the concave curved surface of the outer pressure surface 21B is also along the circumferential direction from the front edge portion 14 to the rear edge portion 15. Is formed.

  The inner pressure surface 21A may be a concave curved surface as a whole, but is not limited thereto. In the present embodiment, the region on the representative root mean radius position Rr side of the inner pressure surface 21A is a concave curved surface, but the region on the inner peripheral portion 13 side has a flat surface or a substantially flat shape close to a flat surface. The outer pressure surface 21B may be a concave curved surface as a whole, but is not limited to this. In the present embodiment, almost the entire outer pressure surface 21B is a concave curved surface.

  The negative pressure surface 22 is formed along the pressure surface 21 to such an extent that the thickness of the blade 12 does not largely change as a whole. Therefore, the negative pressure surface 22 located behind the concave curved surface of the pressure surface 21 is a convex curved surface.

  The maximum value of the radius of curvature of the inner pressure surface 21A is larger than the maximum value of the radius of curvature of the outer pressure surface 21B. Further, the maximum value of the radius of curvature of the suction surface 22A (inner suction surface 22A) in the inner region 12A is larger than the maximum value of the radius of curvature of the suction surface 22B (outer suction surface 22B) in the outer region 12B. That is, the inner pressure surface 21A has a planar shape than the outer pressure surface 21B. The planar shape of the inner pressure surface 21A can also be described as follows.

  That is, in the cross-sectional view of FIG. 7B, an imaginary straight line L5 is drawn connecting the end portion T1 on the inner peripheral portion 13 side of the pressure surface 21 and the intersection T2 between the pressure surface 21 and the representative root mean square radius position Rr. Further, an imaginary straight line L6 is drawn that connects the end T3 of the pressure surface 21 on the outer peripheral portion 16 (bending portion 17 in this embodiment) side and the intersection T2 between the pressure surface 21 and the representative mean-square radius position Rr. In the first embodiment, the maximum distance D1 between the virtual straight line L5 and the pressure surface 21 (inner pressure surface 21A) is larger than the maximum distance D2 between the virtual straight line L6 and the pressure surface 21 (outer pressure surface 21B). small.

  In the cross-sectional view of FIG. 7B, the position on the pressure surface 21 at which the maximum value D1 is provided is provided closer to the intersection T2 than to the end T1. In other words, the position on the pressure surface 21 at which the maximum value D1 is reached is provided in the inner pressure surface 21A at a position that is biased toward the representative root mean square radial position Rr rather than the inner peripheral portion 13 side. That is, the portion on the inner peripheral portion 13 side of the inner region 12A of the blade 12 has a planar shape (two-dimensional shape) than the portion on the outer peripheral portion 16 side (representative root mean square radius position Rr side) of the inner region 12A. Have

  On the other hand, in the propeller fan of the reference example shown in FIG. 7C, the region from the inner peripheral portion 113 to the bent portion 117 of the outer peripheral portion 116 in the pressure surface 121 of each blade 112 is constituted by one large concave curved surface. Has been. The negative pressure surface 122 on the back side of the pressure surface 121 has a shape corresponding to the pressure surface 121. That is, the region from the inner peripheral portion 113 to the bent portion 117 of the outer peripheral portion 116 in the negative pressure surface 122 is configured by one large convex curved surface.

  As shown in FIG. 7C, each blade 112 of the reference example has a three-dimensional shape that extends in the radial direction and curves more greatly in the direction of the rotation axis A0 than in the first embodiment. Specifically, in the cross-sectional view of FIG. 7C, the end portion T11 on the inner peripheral portion 113 side of the pressure surface 121 and the end portion of the pressure surface 121 on the outer peripheral portion 116 (bending portion 117 in this reference example) side. An imaginary straight line L11 connecting T12 is drawn. In this case, the maximum value D11 of the distance between the virtual straight line L11 and the pressure surface 121 is considerably larger than the maximum values D1 and D2 in the first embodiment.

  Therefore, in the reference example, the cross-sectional area of each blade 112 is increased and the volume and weight of the entire propeller fan are increased as compared with the first embodiment. For this reason, there are problems in terms of resource saving and cost reduction.

  Further, each blade 112 of the reference example has a three-dimensional shape as described above, and thus is easily elastically deformed due to the stress generated by the rotation of the propeller fan. That is, since each blade 112 of the reference example has a three-dimensional shape having many elastically starting points, a deformation mode (deformation that extends outward in the radial direction) attempts to deform into a two-dimensional shape when rotating. Mode), such elastic deformation is likely to occur. For this reason, each blade 112 of the reference example needs reinforcement for suppressing elastic deformation, and as a result, has a problem that the weight further increases.

  On the other hand, the propeller fan 4 of the first embodiment shown in FIGS. 7A and 7B has a configuration in which at least two concave curved surfaces as described above are combined instead of one large concave curved surface as in the reference example. Adopted. As shown in FIG. 7B, in the first embodiment, the two concave curved surfaces each have a peak (maximum values D1, D2) of the depth of the concave curved surface. The depths D1, D2 (maximum values D1, D2) of the two concave curved surfaces of the first embodiment are smaller than the depth (maximum value D11) of the concave curved surfaces of the reference example. The radial length of each concave curved surface of the first embodiment is smaller than the radial length of the concave curved surface of the reference example.

  Each blade 12 of the first embodiment having the above-described features has a more planar shape (two-dimensional shape) than each blade 112 of the reference example. In the blade 12 of the first embodiment in which such a shape is adopted, when the thickness distribution from the inner peripheral portion 13 to the outer peripheral portion 16 is the same as that of the blade 112 of the reference example, each blade 12 is compared with the reference example. The cross-sectional area can be reduced. Thereby, since the weight of each blade | wing 12 can be reduced, the volume and weight of the propeller fan 4 whole can also be reduced compared with a reference example.

  Further, each blade 12 of the first embodiment has a planar shape as compared with the blade 112 of the reference example, so that elastic deformation is less likely to occur due to the stress generated by the rotation of the propeller fan 4. That is, since each blade 12 of the first embodiment is originally a two-dimensional shape, the amount of deformation during elastic deformation is small.

  In the present embodiment shown in FIG. 7A, the momentum of the air flowing along the pressure surface 21 varies greatly locally on the outer pressure surface 21B as indicated by arrows in the drawing. On the other hand, in the reference example shown in FIG. 7C, the momentum of the air flowing along the pressure surface 121 changes over the entire pressure surface 121 as indicated by an arrow in the drawing.

(Recessed in the rear edge)
Next, the recessed part 19 of the rear edge part 15 which is the other characteristic of the propeller fan 4 of 1st Embodiment is demonstrated. As shown in FIG. 4A, the rear edge 15 of each blade 12 in the present embodiment is provided with a recess 19 that is recessed toward the front edge 14. The concave portion 19 is provided in a region including the representative square average radius position Rr. The recess 19 is not an essential configuration and can be omitted. Examples of the shape of the recess 19 include, but are not limited to, a substantially V shape and a substantially U shape in front view.

  By providing the concave portion 19 at the representative root mean radius position Rr of the trailing edge 15 where the pressure is likely to rise on the pressure surface 21, the pressure rise at the representative root mean radius position Rr of the trailing edge 15 can be reduced. As a result, the air flowing from the front edge portion 14 toward the rear edge portion 15 along the pressure surface 21 near the rear edge portion 15 avoids the representative root mean square radius position Rr and the hub 11 side and the outer peripheral portion 16. Since it flows to the side, the effect of guiding the airflow in the circumferential direction can be further enhanced. The guide effect in the circumferential direction by the concave portion 19 and the guide effect by providing the peak of the exit angle θ on the hub 11 side and the outer peripheral portion 16 side with the representative root mean square radius position Rr as a boundary are combined. Can be further enhanced.

  Further, in the present embodiment, the bottom 19a of the recess 19 (the portion of the recess 19 that is located at the foremost position in the rotation direction D) is at the representative square average radius position Rr, but is not limited thereto. When the bottom 19a of the recess 19 is at the representative root mean square radius Rr, the above-described guide effect can be further enhanced.

(Air flow during rotation)
Next, the air flow during rotation of the propeller fan 4 of the first embodiment will be described in comparison with a reference example. FIG. 8A is a perspective view showing the air flow in the propeller fan according to the first embodiment, and FIG. 8B is a diagram schematically showing the air flow. FIG. 9A is a perspective view showing the air flow in the propeller fan according to the reference example, and FIG. 9B is a diagram schematically showing the air flow.

  As shown in FIGS. 8A and 8B, in the propeller fan 4 of the first embodiment, the effect of guiding the air flow in the circumferential direction is particularly high in the inner region 12A. The flow to is suppressed.

  On the other hand, in the reference examples shown in FIGS. 9A and 9B, the effect of guiding the air flow in the circumferential direction in the inner region is low, so that the air easily flows toward the outer peripheral portion 116 side.

  As a result, as shown in FIG. 10A, the blowing sound is greatly reduced in the first embodiment as compared to the reference example. Moreover, in the first embodiment, while obtaining the effect of reducing the blowing sound, as shown in FIG. 10 (B), an equivalent air volume can be obtained with a fan motor input substantially equivalent to the reference example. In the first embodiment, weight reduction is achieved without sacrificing air blowing performance.

Second Embodiment
FIG. 11A is a front view showing a part of the propeller fan 4 according to the second embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along the line XIB-XIB in FIG.

  In the propeller fan 4 of this 2nd Embodiment, each blade | wing 12 differs from 1st Embodiment by the point which has the same three-dimensional shape as a reference example. That is, as shown in FIG. 11B, in each blade 12 of the second embodiment, the region from the inner peripheral portion 13 to the bent portion 17 of the outer peripheral portion 16 on the pressure surface 21 is configured by one large concave curved surface. Has been.

  However, the second embodiment differs from the reference example in that each blade 12 has a characteristic of the exit angle θ similar to that of the first embodiment shown in FIG. 3, for example. That is, in the second embodiment, each blade 12 has a peak of the exit angle θ of the trailing edge 15 in the outer region 12B radially outside the representative mean square radius position Rr and is more than the representative mean square radius position Rr. The inner region 12 </ b> A on the radially inner side also has a shape having a peak of the exit angle θ of the rear edge 15.

<Summary of Embodiment>
As described above, in the first embodiment and the second embodiment, the representative square mean radius position Rr that bisects the flow passage area of the propeller fan 4 in the radial inner side and the radial outer side is used as a reference. Noise can be effectively reduced by providing each of the outer region 12B occupying half the road area and the inner region 12A occupying the other half of the channel area with a function of guiding air in the circumferential direction.

  That is, in these aspects, by adopting a blade shape in which the peak of the exit angle θ of the rear edge 15 exists in the outer region 12B, the work amount of the fan in the rear edge 15 of the outer region 12B increases. The effect of guiding the air flowing along the pressure surface 21 of the outer region 12B in the circumferential direction can be enhanced. Further, in these aspects, by adopting a blade shape in which the peak of the exit angle θ of the rear edge 15 exists also in the inner region 12A, the work of the fan in the rear edge 15 of the inner region 12A also increases. Therefore, the effect of guiding the air flowing along the pressure surface 21 of the inner region 12A in the circumferential direction can also be enhanced. Thereby, since it can suppress that an airflow flows into the outer peripheral part 16 side (blade end side), increase of the air flow (leakage flow) which goes around from the pressure surface 21 side to the negative pressure surface 22 side in the vicinity of the outer peripheral part 16 is suppressed. The As a result, the generation of blade tip vortices due to leakage flow is suppressed, so that noise can be reduced. In addition, a decrease in fan performance is suppressed by suppressing an increase in leakage flow.

  In the first embodiment, the maximum value of the curvature radius of the pressure surface 21 in the inner region 12A is larger than the maximum value of the curvature radius of the pressure surface 21 in the outer region 12B. That is, in this aspect, the inner region 12A has a smaller radius of curvature than the outer region 12B and has a more planar shape, so that the cross-sectional area of the blade 12 can be reduced particularly in the inner region 12A. Thereby, weight reduction of the blade | wing 12 can be achieved and the increase in volume can be suppressed.

  In the first embodiment, the pressure surface 21 in the inner region 12A and the pressure surface 21 in the outer region 12B include a concave curved surface. In this aspect, since the pressure surface 21 of the inner region 12A and the pressure surface 21 of the outer region 12B both include a concave curved surface, the effect of guiding the air flowing along the pressure surface 21 in each region in the circumferential direction is further increased. Can be increased.

  Moreover, in the first embodiment, the maximum value of the pressure surface 21 in the outer region 12B is smaller than the maximum value of the pressure surface 21 in the inner region 12A, and the pressure surfaces of these regions 12A and 12B both include a concave curved surface. Is adopted. The outer region 12B close to the outer peripheral portion 16 has a large pressure gradient between the pressure surface 21 and the negative pressure surface 22. Therefore, by setting the radius of curvature to be small, air flowing along the pressure surface 21 of the outer region 12B is circumferentially moved. The effect of guiding to can be further enhanced. As a result, the occurrence of leakage flow is further suppressed as the entire pressure surface 21.

  In the first embodiment, one concave surface is provided in each of the inner region 12A and the outer region 12B, and there is one peak of the exit angle θ. With such a relatively simple structure, the weight of the blades 12 can be reduced and the increase in volume can be suppressed while reducing noise.

  In the first and second embodiments, the rear edge 15 of the blade 12 is provided with a recess 19 that is recessed toward the front edge 14 in a region that includes the representative root mean square radius position Rr. In these aspects, since the recess 19 is provided in a region including the representative root mean square radius position Rr of the trailing edge 15 where the pressure increase is greatest, the pressure increase is reduced in the vicinity of the recess 19. As a result, air flowing from the front edge portion 14 to the rear edge portion 15 side flows to the hub 11 side and the outer peripheral portion 16 side in the vicinity of the rear edge portion 15 so as to avoid the representative root mean square radius position Rr. Can be further enhanced in the circumferential direction.

  Further, in each blade 12 in the first embodiment, as is apparent from the positional relationship between the auxiliary line L1 and the positions P1 and P2 in FIG. 2, the position P1 of the connecting portion between the front edge portion 14 and the outer peripheral portion 16 is Further, it is located on the front side in the rotational direction D with respect to the position P2 of the connecting portion between the front edge portion 14 and the inner peripheral portion 13.

  In addition, as apparent from the positional relationship between the auxiliary line L2 and the positions P3 and P4 in FIG. 2, in each blade 12 in the present embodiment, the position P3 of the connecting portion between the trailing edge 15 and the outer peripheral portion 16 is It is located on the rear side in the rotational direction D with respect to the position P4 of the connection portion between the rear edge portion 15 and the inner peripheral portion 13.

  On the other hand, in the propeller fan of the reference example shown in FIG. 4B, as is clear from the positional relationship between the auxiliary line L12, the position P13, and the position P14, each blade 112 has a trailing edge portion 115 and an outer peripheral portion 116. The position P13 of the connecting portion is located on the front side in the rotational direction D with respect to the position P14 of the connecting portion between the rear edge portion 115 and the inner peripheral portion 113.

  Therefore, in the first embodiment shown in FIG. 2, compared with the reference example shown in FIG. 4B, the size of the inner region 12A is particularly reduced, and thus the weight of the blade 12 is reduced. ing.

<Modification>
As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

  In the said embodiment, although the case where the propeller fan was used for the outdoor unit 1 of an air conditioner was illustrated, it is not limited to this. The propeller fan can be used as a fan for an indoor unit of an air conditioner, for example, and can also be used as a fan such as a ventilation fan.

  In 1st Embodiment, although the case where the concave surface was contained in each of the pressure surface 21A of the inner side area | region 12A and the pressure surface 21B of the outer side area | region 12B was illustrated, it is not limited to this. For example, the pressure surface 21A of the inner region 12A is a flat surface, and the pressure surface of the outer region 12B is a curved surface (concave curved surface or convex curved surface). Further, there is a form in which the pressure surface 21A of the inner region 12A is a curved surface (concave curved surface or convex curved surface), and the pressure curved surface of the outer region 12B is flat.

DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Casing 3 Outdoor heat exchanger 4 Propeller fan 5 Motor 6 Bell mouth 7 Outlet 8 Axial fan 11 Hub 12 Blade | wing 12A Inner area | region 12B Outer area | region 13 Inner peripheral part 14 Front edge part 15 Rear edge part 16 Outer peripheral part 17 Bending portion 18 Outer peripheral edge portion 19 Recessed portion 19a Bottom portion 21 Pressure surface 21A Inner pressure surface 21B Outer pressure surface 22 Negative pressure surface A0 Rotating shaft D Rotating direction Rr Representative square mean radius position θ Exit angle

(2) In the propeller fan, the maximum value of the radius of curvature of the pressure surface (21) in the inner region (12A) is not greater than the maximum value of the curvature radius of the outer area pressure surface in (12B) (21) .

Claims (6)

A propeller fan comprising a blade (12),
The blade (12) has a peak of the exit angle (θ) of the trailing edge (15) in the outer region (12B) radially outside the representative root mean radius position (Rr) and the representative root mean radius position. A propeller fan having a shape having a peak of the exit angle (θ) of the rear edge (15) in the inner region (12A) radially inward of (Rr).   The propeller fan according to claim 1, wherein the maximum value of the radius of curvature of the pressure surface (21) in the inner region (12A) is greater than the maximum value of the radius of curvature of the pressure surface (21) in the outer region (12B). .   The propeller fan according to claim 1 or 2, wherein the pressure surface (21) in the inner region (12A) and the pressure surface (21) in the outer region (12B) include a concave curved surface.   The inner region (12A) and the outer region (12B) are each provided with a concave curved surface, and each has a peak of the exit angle (θ). The propeller fan according to claim 1.   The rear edge (15) of the blade (12) is provided with a recess (19) that is recessed toward the front edge in a region including the representative root mean square position (Rr). The propeller fan according to any one of the above.   An air conditioner comprising the propeller fan (4) according to any one of claims 1 to 5.