CN104641121B - Propeller type fan and possess the air conditioner of this propeller type fan - Google Patents

Abstract

Propeller type fan (4) possesses blade (12), blade (12) is in following shape: have the peak value of the exit angle (θ) of hinder marginal part (15) in the exterior lateral area (12B) being positioned at radial outside compared with representing root mean square radii position (Rr), further, also there is the peak value of the exit angle (θ) of hinder marginal part (15) in the inside region (12A) being positioned at radially inner side compared with representing root mean square radii position (Rr).

Description

Propeller fan and air conditioner equipped with the propeller fan

technical field

The present invention relates to a propeller fan and an air conditioner provided with the propeller fan.

Background technique

Conventionally, propeller fans used in air conditioners and the like are known. When the propeller fan rotates, an air flow (leakage flow) from the high-pressure pressure surface side to the low-pressure negative pressure surface side occurs near the outer periphery of the blade, and a vortex is formed near the outer periphery of the blade due to this air flow. (wing tip vortex). Such wing tip vortices cause noise.

The propeller fan disclosed in Patent Document 1 attempts to reduce noise by providing a bent portion on the outer peripheral portion of the blade to stabilize the tip vortex.

However, if only the bent portion is provided on the outer peripheral portion of the blade as in Patent Document 1, a sufficient noise reduction effect may not necessarily be obtained.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-072948

Contents of the invention

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

The propeller fan according to the present invention includes a hub and a blade connected to the hub, and the blade has a shape having an outlet angle of a trailing edge in an outer region located radially outer than a representative root mean square radius position. , and also has a peak value of the exit angle of the trailing edge portion in the inner region located radially inward compared with the representative root mean square radius position, and the exit angle of the trailing edge portion is obtained by cutting along the circumferential direction. When describing the blade, the angle formed by the tangent to the pressure surface at the rear edge and the straight line perpendicular to the rotation axis of the propeller fan, the representative root mean square radius position is obtained by using the representative radius R of the blade and the representative radius r of the hub is calculated by the following formula: representative root mean square radius position Rr=((R ² +r ² )/2) ⁰ _. ⁵ , when the outer diameter of the blade is rotating When the axial direction is constant, the representative radius R of the blade is 1/2 of the outer diameter of the blade, and when the outer diameter of the blade is not constant in the direction of the rotation axis, the radius R of the blade is The representative radius R is the average value of the minimum blade radius R1 and the maximum blade radius R2, and when the outer diameter of the blade hub is constant in the direction of the rotation axis, the representative radius r of the blade hub is the outer diameter of the blade hub In the case that the outer diameter of the hub is not constant in the direction of the rotation axis, the representative radius r of the hub is the average value of the minimum hub radius r1 and the maximum hub radius r2, The maximum value of the radius of curvature of the pressure surface of the inner region is greater than the maximum value of the radius of curvature of the pressure surface of the outer region.

Description of drawings

Fig. 1 is a cross-sectional view showing a schematic configuration of an outdoor unit of an air conditioner according to an embodiment of the present invention.

Fig. 2 is a front view showing the propeller fan according to the first embodiment of the present invention.

3 is a graph showing the relationship between the radial position of the rear edge portion of the propeller fan and the outlet angle.

(A) of FIG. 4 is a front view showing the radial positions corresponding to the five radial positions A1-A5 of the graph of FIG. 3 in the blade of the propeller fan of the first embodiment, and (B) is a front view showing The front view of the radial positions corresponding to the five radial positions A1-A5 in the coordinate diagram of FIG. 3 among the blades of the example propeller fan.

Fig. 5 is a diagram for explaining a representative root mean square radius position of a propeller fan.

Fig. 6 is a sectional view taken along the circumferential direction of the blade.

(A) and (B) of FIG. 7 are sectional views taken along the line VIIA-VIIA of FIG. 4(A), and (C) is a sectional view taken along the line VIIC-VIIC of FIG. 4(B).

(A) of FIG. 8 is a perspective view of the air flow in the propeller fan concerning 1st Embodiment, (B) is a figure which schematically shows the air flow.

(A) of FIG. 9 is a perspective view showing the flow of air in the propeller fan according to the reference example, and (B) is a diagram schematically showing the flow of the air.

(A) and (B) of FIG. 10 are graphs comparing the characteristics of the propeller fan according to the first embodiment with those of the propeller fan according to the 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) of FIG. 11 is a front view showing a part of the propeller fan according to the second embodiment of the present invention, and (B) is a sectional view taken along line XIB-XIB of (A).

detailed description

<Overall structure of the air conditioner>

Next, a propeller fan according to an embodiment of the present invention and an air conditioner including the propeller fan will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing a schematic configuration of an outdoor unit 1 of an air conditioner according to an embodiment of the present invention. The air conditioner includes an outdoor unit 1 shown in FIG. 1 and an indoor unit not shown in the figure. The outdoor unit 1 includes an outdoor heat exchanger 3 , a propeller fan 4 , a motor 5 , a compressor (not shown), and the like, and these are housed in a housing 2 . The indoor unit includes an expansion mechanism (not shown), an indoor heat exchanger, and the like. The compressor, the outdoor heat exchanger 3 , the expansion mechanism, the indoor heat exchanger, and refrigerant piping (not shown) connecting them constitute a 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 housing 2 and the air outlet 7 is provided on the front side of the housing 2 , but the present invention is not limited thereto. In the outdoor unit 1, the air outlet 7 may be provided in the upper part of the casing 2, for example. The air outlet 7 is provided with a fan cover 7a having a grill structure.

Propeller fan 4 is arranged inside air outlet 7 of housing 2 . The propeller fan 4 is connected to the shaft 5a of the motor 5, and rotates around the rotation axis A0 by the motor 5. In the present embodiment, the rotation axis A0 of the propeller fan 4 faces the front-rear direction (horizontal direction), but it is not limited thereto. The rotation axis A0 may be oriented in a direction inclined with respect to the horizontal direction, for example. In addition, for example, in the outdoor unit 1 in which the air outlet 7 is provided on the upper portion of the casing 2, the rotation axis A0 of the propeller fan 4 may be oriented in the vertical 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 an area X (suction area X) and an area Y (blowing area Y), wherein area X is located on the upstream side of the air flow compared to the propeller fan 4, and area Y is located on the upstream side of the propeller fan 4. compared to the downstream side of the air flow. The bell mouth 6 is an annular member along the periphery of the propeller fan 4 and guides the air passing through the outdoor heat exchanger 3 to the air outlet 7 . The bell mouth 6 is arranged with a small gap with the propeller fan 4 so as not to come into contact with the propeller fan 4 .

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

<First Embodiment>

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

The hub 11 generally has a cylindrical shape, a truncated cone shape, or the like, 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 thereof is substantially constant, whereas in the case of the truncated conical hub 11 , for example, the outer diameter becomes larger or smaller toward the rotation axis A0. In addition, the hub 11 may have, for example, a combination of a cylindrical shape and a truncated cone shape, or may have other shapes. The rotation axis A0 of the propeller fan 4 is located at the center of the hub 11 .

Each blade 12 has: an inner peripheral portion 13 located radially inward (on the hub 11 side) and connected to the hub 11; a leading edge portion 14 located on the front side in the rotation direction D; The rear edge portion 15 on the opposite side of D) and the outer peripheral portion 16 on the radially outer side. Each blade 12 has a twisted shape so that the leading edge portion 14 is located entirely in the suction area X rather than the trailing edge portion 15 . In addition, each blade 12 has a pressure surface 21 located on the outlet 7 side (blowout area Y side) and a negative pressure surface 22 located on the opposite side (suction area X side) (see FIG. 6 ).

As shown in FIG. 2 , outer peripheral portion 16 includes bent portion 17 where the end of vane 12 is bent toward negative pressure surface 22 (suction region X side) and outer peripheral portion 18 constituting the radially outer edge of vane 12 . 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 generation of a 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 near 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. In addition, the bent portion 17 may be omitted, and in this case, the outer peripheral portion 16 is constituted by the outer peripheral edge portion 18 .

(exit angle at trailing edge)

Next, the characteristic of the propeller fan 4 of the first embodiment, that is, the outlet angle θ of the rear edge portion 15 will be described. In the graph of FIG. 3 , the solid line represents the relationship between the radial position of the rear edge portion 15 of the propeller fan 4 of the first embodiment shown in FIG. 2 and FIG. 4(A) and the outlet angle θ, and the dashed line represents The relationship between the radial position of the rear edge portion 115 of the propeller fan 104 of the reference example in FIG. 4(B) and the outlet angle θ.

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 (bent portion 117 , outer peripheral edge portion 118 ). In addition, each blade 112 has a pressure surface 121 and a negative pressure surface 122 (see FIG. 7(C)).

As shown in FIG. 3 , in the rear edge portion 15 of each blade 12 of the propeller fan 4 according to the first embodiment, there are a plurality of peaks of the outlet angle θ. Specifically, at the trailing edge portion 15 of each blade 12, there are two peaks of the exit angle θ, one of which is located at the trailing edge portion of the outer region 12B that is radially outer than the representative root-mean-square radius position Rr. 15. Another peak is located at the trailing edge portion 15 of the inner region 12A located radially inner than the representative root mean square radius position Rr.

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

On the other hand, in the trailing edge portion 15 of each blade 12 of the reference example shown in FIG. 4(B), there is only one peak of the exit angle θ. This peak is provided at the trailing edge portion 115 of the outer region located radially outer than the representative root-mean-square radius position Rr. The outlet angle θ of the rear edge portion 115 in this reference example is designed to gradually increase from the inner peripheral portion 113 toward the outer peripheral portion 116 side, and the peak value of the outlet angle θ of the rear edge portion 115 is set at a value corresponding to the representative mean square. The root radius position Rr is located in an outer region (a position near the outer peripheral portion 116 ) on the outer side in the radial direction.

The representative root-mean-square radius position Rr is a radius position at which the flow path area 2 of the propeller fan 4 (104) is equally divided into a central side (hub side) and an outer peripheral side. Fig. 5 is a diagram for explaining the representative root mean square radius position Rr of the propeller fan 4 (104). The representative root mean square radius position Rr is calculated using the following formula (1) represented by the representative radius R of the blade 12 (112) and the representative radius r of the hub 11 (111).

Represents the root mean square radius 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 one-half of the outer diameter of the blade 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 the 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 of half of the outer diameter when the outer diameter of the hub is constant in the direction of the rotation axis.

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

That is, the representative radius r of the hub is the 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. 4(A) and (B). For example, radial position A1 is a position where a circle of radius A1 centered on rotation axis A0 overlaps blade 12 ( 112 ) when the propeller fan is viewed from the front as shown in FIG. 4(A) and (B). Since the same is true for the radial positions A2-A5, description thereof will be omitted.

In the first embodiment and the reference example shown in FIG. 4(A) and (B), the radius position A3 coincides with the representative root mean square radius position Rr, but the present invention is not limited thereto. Radius 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 on the hub 11 side 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.

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

In the first embodiment, as shown in FIG. 3 , the peak value of the exit angle θ of the inner region 12A, that is, the maximum value of the exit angle θ of the inner region 12A is the exit angle θ2 at the radial position A2 (first peak position). In addition, the peak value of the exit angle θ of the outer region 12B, that is, the maximum value of the exit angle θ of 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 this embodiment, between the peak positions (radius position A2 and radius position A4), the minimum value of the outlet angle θ is the outlet angle θ3 representing the root mean square radius position Rr (radius position A3), but it is not limited here. The minimum value of the outlet angle θ between the peak positions may be an outlet angle at a position deviated from the representative root mean square radius position Rr.

In this embodiment, the outlet angle θ of 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). In addition, the exit angle θ of the rear edge portion 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 outlet angle θ of the rear edge portion 15 of the present embodiment changes in a substantially M-shape as shown in FIG. 3 .

A specific example of the difference between the exit angles θ2 and θ4 at the peak positions and the exit angle θ3 which is the minimum value therebetween will be given as follows. That is, the difference between the exit angle θ2 and the exit angle θ3 can be set, for example, within a range of 0.5° to 10° or a range of 1° to 5°. In addition, the difference between the exit angle θ4 and the exit angle θ3 can be set, for example, within a range of 0.5° to 10° or a range of 1° to 5°.

In addition, in an example shown as an embodiment in FIG. 3 , 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, but this is not limiting. here. The exit angle θ2 and the exit angle θ4 may have different values from each other. Specifically, the exit angle θ2 may be greater than the exit angle θ4, or may be smaller than the exit angle θ4.

(radius of curvature of the pressure surface)

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

As shown in FIG. 7(A), in the propeller fan 4 of the first embodiment, the pressure surface 21A (the inner pressure surface 21A) of the inner region 12A includes a concave curved surface, and the pressure surface 21B (the outer pressure surface 21B) of the outer region 12B ) also includes a concave curved surface different from the concave curved surface. In the present embodiment, the outer pressure surface 21B represents a region between the 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 root 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 aligned in the radial direction. As shown in FIG. 7(A), the pressure surface 21C representing the root mean square radius position Rr where the two concave curved surfaces are connected and its vicinity is a convex curved surface.

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

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

In addition, the negative pressure surface 22 is formed along the pressure surface 21 so that the overall thickness of the blade 12 does not change much. Therefore, the negative pressure surface 22 located on the back side of 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. In addition, the maximum radius of curvature of negative pressure surface 22A (inner negative pressure surface 22A) of inner region 12A is larger than the maximum value of curvature radius of negative pressure surface 22B (outer negative pressure surface 22B) of outer region 12B. That is, the inner pressure surface 21A has a flatter shape than the outer pressure surface 21B. The flat shape of the inner pressure surface 21A can also be described as follows.

That is, in the sectional view of FIG. 7(B), an imaginary straight line L5 connecting the end T1 of the pressure surface 21 on the inner peripheral portion 13 side and the intersection T2 of the pressure surface 21 and the root mean square radius position Rr is drawn. In addition, draw a virtual straight line L6 connecting the end T3 of the pressure surface 21 on the outer peripheral portion 16 (in this embodiment, the bent portion 17 ) side and the intersection point T2 of the pressure surface 21 and the root mean square radius position Rr. In the first embodiment, the maximum value D1 of the distance between the imaginary straight line L5 and the pressure surface 21 (inner pressure surface 21A) is smaller than the maximum value D2 of the distance between the imaginary straight line L6 and the pressure surface 21 (outer pressure surface 21B).

In the sectional view of FIG. 7(B), the position on the pressure surface 21 at which the maximum value D1 is obtained is set closer to the intersection T2 than the end T1. That is, the position on the pressure surface 21 at which the maximum value D1 becomes the inner pressure surface 21A is not on the inner peripheral portion 13 side, but on the side of the representative root mean square radius position Rr. That is, the portion of the inner region 12A of the blade 12 on the inner peripheral portion 13 side has a flatter shape (two-dimensional shape) than the portion of the inner region 12A on the outer peripheral portion 16 side (representing the root mean square radius position Rr side). .

On the contrary, in the propeller fan of the reference example shown in FIG. form. 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 area from the inner peripheral portion 113 to the bent portion 117 of the outer peripheral portion 116 of the negative pressure surface 122 is formed by a large convex curved surface.

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

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

In addition, since each blade 112 of the reference example has the above-mentioned three-dimensional shape, it is easy to elastically deform 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 a plurality of origins of elastic deformation, the deformation mode (deformation mode intending to extend radially outward) deformed into a two-dimensional shape when rotating ), such elastic deformation is prone to occur. Therefore, each blade 112 of the reference example needs to be reinforced so as to suppress elastic deformation, and as a result, there is a problem that the weight is further increased.

On the other hand, the propeller fan 4 of the first embodiment shown in Fig. 7(A) and (B) is not a large concave curved surface as in the reference example, but uses a combination of at least two concave curved surfaces as described above. Structure. As shown in FIG. 7(B), in the present embodiment, each of the two concave curved surfaces has a peak value (maximum value D1, D2) of the depth of the concave curved surface. The depths D1, D2 (maximum value D1, D2) of the two concave curved surfaces of the first embodiment are smaller than the depth (maximum value D11) of the concave curved surface of the reference example. In addition, the radial length of each concave curved surface of the first embodiment is also smaller than the radial length of the concave curved surface of the reference example.

Each blade 12 of the first embodiment having the above features has a flatter shape (two-dimensional shape) than each blade 112 of the reference example. In the blade 12 of the first embodiment having such a shape, 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, the cross-sectional area of each blade 12 can be reduced compared with the reference example. get smaller. Accordingly, since the weight of each blade 12 can be reduced, the volume and weight of the propeller fan 4 as a whole can also be reduced compared to the reference example.

In addition, since each blade 12 of the first embodiment has a flatter shape than the blade 112 of the reference example, elastic deformation due to stress generated by the rotation of the propeller fan 4 is less likely to occur. That is, each blade 12 of the first embodiment has a two-dimensional shape originally, and therefore, the amount of deformation during elastic deformation is small.

In addition, in the present embodiment shown in FIG. 7(A), the movement amount of the air flowing along the pressure surface 21 locally and largely changes on the outer pressure surface 21B as indicated by arrows in the figure. In contrast, in the reference example shown in FIG. 7(C), the movement amount of the air flowing along the pressure surface 121 varies over the entire pressure surface 121 as indicated by arrows in the figure.

(recess of rear edge part)

Next, another feature of propeller fan 4 according to the first embodiment, that is, recessed portion 19 of rear edge portion 15 will be described. As shown in FIG. 4(A) , in the rear edge portion 15 of each blade 12 of the present embodiment, a concave portion 19 recessed toward the front edge portion 14 side is provided. The concave portion 19 is provided in a region including the position Rr representing the root-mean-square radius. The concave portion 19 is not an essential structure and may be omitted. The shape of the concave portion 19 includes, for example, a substantially V-shape and a substantially U-shape in a front view, but is not limited thereto.

By providing the concave portion 19 at the representative root mean square radius position Rr of the rear edge portion 15 where the pressure of the pressure surface 21 tends to increase, the pressure increase at the representative root mean square radius position Rr of the rear edge portion 15 can be reduced. Accordingly, the air flowing from the leading edge portion 14 to the trailing edge portion 15 side along the pressure surface 21 flows toward the hub 11 side and the outer peripheral portion 16 side while avoiding the representative root mean square radius position Rr in the vicinity of the trailing edge portion 15. , can further improve the effect of guiding the airflow along the circumferential direction. Utilizing the circumferential guiding effect of the concave portion 19 and the guiding effect of setting the peaks of the outlet angle θ respectively on the hub 11 side and the outer peripheral portion 16 side with the representative root mean square radius position Rr as the boundary, it is possible to further improve The effect of directing the airflow in the circumferential direction.

In addition, in this embodiment, the bottom 19a of the recessed part 19 (the frontmost part of the recessed part 19 in the rotation direction D) is at the representative root mean square radius position Rr, but it is not limited to this. When the bottom 19a of the concave portion 19 is at the position Rr representing the root mean square radius, the above-mentioned guiding 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. 8(A) is a perspective view showing the flow of air in the propeller fan according to the first embodiment, and FIG. 8(B) is a diagram schematically showing the flow of the air. FIG. 9(A) is a perspective view showing the flow of air in the propeller fan according to the reference example, and FIG. 9(B) is a diagram schematically showing the flow of the air.

As shown in FIG. 8(A) and (B), in the propeller fan 4 of the first embodiment, especially in the inner region 12A, the effect of guiding the air flow in the circumferential direction is high, and as a result, the flow toward the outer peripheral portion 16 side get suppressed.

In contrast, in the reference example shown in FIGS. 9(A) and (B), the effect of guiding the air flow in the circumferential direction is low in the inner region, and the air tends to flow toward the outer peripheral portion 116 side.

As a result, in the first embodiment shown in FIG. 10(A) , the blowing sound was significantly reduced compared with the reference example. Furthermore, in the first embodiment, when the reduction effect of the blowing noise is obtained, the same air volume is obtained with the fan motor input substantially equal to that of the reference example shown in FIG. 10(B) . In the first embodiment, weight is reduced without sacrificing air delivery performance.

<Second Embodiment>

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

The propeller fan 4 of this second embodiment differs from the first embodiment in that each blade 12 has the same three-dimensional shape as that of the reference example. That is, as shown in FIG. 11(B), in each blade 12 of the second embodiment, the region of the pressure surface 21 from the inner peripheral portion 13 to the bent portion 17 of the outer peripheral portion 16 is formed by a large concave curved surface.

However, the second embodiment differs from the reference example in that each vane 12 has the same characteristic of the exit angle θ as that of the first embodiment shown in FIG. 3 , for example. That is, in the second embodiment, each blade 12 has a shape that has a peak value of the exit angle θ of the trailing edge portion 15 in the outer region 12B located radially outer than the representative root mean square radius position Rr, and , there is also a peak of the exit angle θ of the trailing edge portion 15 in the inner region located radially inner than the representative root mean square radius position Rr.

<Summary of Embodiment>

As described above, the first embodiment and the second embodiment use the representative root-mean-square radius position Rr that divides the flow path area of the propeller fan 4 into two equal parts, the radially inner side and the radially outer side, as a reference, and make the occupied flow path area Half of the outer region 12B and the inner region 12A occupying the remaining half of the flow path area each function to guide air in the circumferential direction, thereby effectively reducing noise.

That is, in these structures, by adopting a blade shape having a peak value of the outlet angle θ of the rear edge portion 15 in the outer region 12B, the workload of the fan at the rear edge portion 15 of the outer region 12B increases, and the flow rate along the outer region can be improved. The air flowing on the pressure surface 21 of 12B has the effect of guiding the circumferential direction. Furthermore, in these configurations, by adopting a blade shape having a peak value of the exit angle θ of the rear edge portion 15 also in the inner region 12A, the workload of the fan at the rear edge portion 15 of the inner region 12A is increased, and the speed along the The air flowing on the pressure surface 21 of the inner region 12A has the effect of guiding the circumferential direction. This prevents the airflow from flowing toward the outer peripheral portion 16 (airfoil tip side), thereby suppressing an increase in the air flow (leakage) that goes around the outer peripheral portion 16 from the pressure surface 21 side to the negative pressure surface 22 side. As a result, generation of tip vortices due to leakage flow is suppressed, and noise can be reduced. Furthermore, by suppressing an increase in leakage flow, a decrease in fan performance is also suppressed.

In the first embodiment, the maximum value of the radius of curvature of the pressure surface 21 of the inner region 12A is larger than the maximum value of the radius of curvature of the pressure surface 21 of the outer region 12B. That is, in this embodiment, since the inner region 12A has a smaller maximum radius of curvature and has a flatter shape than the outer region 12B, the cross-sectional area of the blade 12 can be reduced especially in the inner region 12A. Accordingly, it is possible to reduce the weight of the blade 12 and suppress an increase in volume.

In the first embodiment, the pressure surface 21 of the inner region 12A and the pressure surface 21 of the outer region 12B include concave curved surfaces. In this structure, both the pressure surface 21 of the inner region 12A and the pressure surface 21 of the outer region 12B have concave curved surfaces, so that the effect of guiding the air flowing along the pressure surface 21 in the circumferential direction can be further enhanced in each region.

Moreover, in the first embodiment, the maximum value of the pressure surface 21 of the outer region 12B is smaller than the maximum value of the pressure surface 21 of the inner region 12A, and the pressure surfaces of these regions 12A and 12B both adopt a structure including a concave curved surface. The pressure gradient between the pressure surface 21 and the negative pressure surface 22 of the outer region 12B close to the outer peripheral portion 16 is large, and the radius of curvature is set to be small, so that the air flowing along the pressure surface 21 of the outer region 12B can be further guided to the periphery. to the effect. As a result, the occurrence of leakage flow is further suppressed on the entire pressure surface 21 .

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

In the first and second embodiments, the trailing edge portion 15 of the blade 12 is provided with a concave portion 19 recessed toward the front edge portion 14 in a region including the root-mean-square radius position Rr. In these structures, since the recess 19 is provided in a region including the root-mean-square radius position Rr of the trailing edge portion 15 where the pressure rise is the largest, the pressure rise decreases near the recess 19 . Accordingly, the air flowing from the leading edge portion 14 to the trailing edge portion 15 side flows toward the hub 11 side and the outer peripheral portion 16 side while avoiding the representative root mean square radius position Rr in the vicinity of the trailing edge portion 15, so that further improvement can be achieved. The effect of directing the airflow in a circumferential direction.

In addition, in each blade 12 of the first embodiment, as can be seen from the positional relationship between the auxiliary line L1 and the positions P1 and P2 in FIG. The position P2 and the position P1 of the connecting portion of the front edge portion 14 and the outer peripheral portion 16 are located on the front side in the rotation direction D. As shown in FIG.

In addition, as can be seen from the positional relationship between the auxiliary line L2 and the positions P3 and P4 in FIG. P4, the position P3 of the connecting portion between the rear edge portion 15 and the outer peripheral portion 16 is located on the rear side in the rotation direction D. As shown in FIG.

On the other hand, in the propeller fan of the reference example shown in FIG. The position P14 of the connection portion with the inner peripheral portion 113 and the position P13 of the connection portion between the rear edge portion 115 and the outer peripheral portion 116 are located on the front side in the rotation direction D. As shown in FIG.

Therefore, in the first embodiment shown in FIG. 2 , compared with the reference example shown in FIG. 4(B), the size of the inner region 12A is reduced particularly, thereby reducing the weight of the blade 12 .

<Modification>

As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, Various changes, improvement, etc. are possible in the range which does not deviate from the summary.

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

In the first embodiment, the case where the pressure surface 21A of the inner region 12A and the pressure surface 21B of the outer region 12B each include a concave curved surface was exemplified, but the present invention is not limited thereto. For example, a structure in which the pressure surface 21A of the inner region 12A is a flat surface and the pressure-curved surface of the outer region 12B is a curved surface (concave curved surface or convex curved surface) can be mentioned. In addition, a structure in which the pressure surface 21A of the inner region 12A is a curved surface (concave curved surface or convex curved surface) and the buckling surface of the outer region 12B is a flat surface may also be mentioned.

In addition, the summary description of the above-mentioned embodiment will be as follows.

(1) The propeller fan of the present invention is provided with a blade having a shape having a peak value of the outlet angle of the trailing edge portion in an outer region located radially outer than the representative root mean square radius position, and having a peak value at the outlet angle relative to The representative root mean square radius position also has a peak value of the exit angle of the trailing edge portion in the inner region located radially inward.

In this structure, using the representative root mean square radius position that divides the flow path area of the propeller fan into two equal parts, the radially inner side and the radially outer side, as a reference, the outer area that occupies half of the flow path area and the area that occupies half of the flow path area The remaining half of the inner regions respectively have the function of directing the air in the circumferential direction, thereby effectively reducing noise. Specifically, it is as follows.

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

On the other hand, in this structure, by adopting the blade shape having the peak of the outlet angle of the rear edge portion in the outer region, the workload of the fan at the rear edge portion of the outer region increases, and therefore, the pressure along the outer region can be increased. Surface-flowing air guides the circumferential effect. Moreover, in this structure, also by adopting the blade shape having the peak of the exit angle of the rear edge portion in the inner region, the workload of the fan at the rear edge portion of the inner region increases, and therefore, it is also possible to improve the flow rate along the inner region. The pressure side of the air flow guides the circumferential effect. This prevents the air flow from flowing toward the outer peripheral portion (airfoil tip side), thereby suppressing an increase in the air flow (leakage flow) that goes around from the pressure surface side to the negative pressure surface side in the vicinity of the outer peripheral portion. As a result, generation of tip vortices due to leakage flow is suppressed, and noise can be reduced. Furthermore, by suppressing an increase in leakage flow, a decrease in fan performance is also suppressed.

In addition, as described above, in the propeller fan having the above-mentioned structure, the flow of the air flowing into the pressure surface from the leading edge of the blade to the radially outer side on the outer peripheral portion side (airfoil end side) is suppressed, and the flow in the circumferential direction occupies dominance. Accordingly, the height of the hub (thickness of the hub in the direction of the rotation axis A0 ) can be reduced, and thus the weight of the propeller fan can be reduced. Specifically, it is as follows.

In a propeller fan, if the height of the hub is reduced, the height of the inner peripheral portion of the blade connected to the outer peripheral surface of the hub (joint portion of the blade with the hub) also needs to be reduced. The blade height is a difference in height (difference in height in the rotation axis direction) between one end (end on the leading edge side) and the other end (end on the trailing edge side) of a camber line in the joint portion. If the blade height becomes smaller, the workload of the blade in the vicinity of the joint portion (lift of the blade head) becomes smaller, and the air flowing into the pressure surface from the leading edge portion tends to flow toward the blade end side with a large workload (lift of the blade head). Rising large airfoil side) and flow radially outward. Therefore, if the height of the hub is reduced in the conventional propeller fan, the flow in the circumferential direction cannot be dominated. In order to obtain the workload of the blade near the junction (the lift of the blade head), it can be considered that the expansion of the fan-shaped blade from the junction toward the wing tip becomes larger, that is, the chord near the junction is increased. A method of increasing the area of the pressure surface in the vicinity of the joint (increasing the integral value) by increasing the length. However, according to this method, the weight of the blade increases, and the weight of the propeller fan cannot be reduced.

On the other hand, in the propeller fan of the present invention, as described above, by adopting a blade having a shape having a peak of the exit angle of the trailing edge portion in the outer region and having a peak of the trailing edge portion in the inner region, it is possible to Circumferential air flow predominates. Therefore, in the propeller fan of the present invention, the height of the hub can be made smaller than conventional ones while maintaining a state in which the air flow in the circumferential direction is dominant, thereby reducing the weight of the propeller fan.

In addition, in the propeller fan of the present invention, the outlet angle at the peak position of the outer region and the outlet angle at the peak position of the inner region may be the same value or different values. In the case of different values, the exit angle of the peak position of the outer region may be larger than the exit angle of the peak position of the inner region, or smaller than the exit angle of the peak position of the inner region.

(2) In the propeller fan, preferably, a maximum value of a radius of curvature of a pressure surface of the inner region is larger than a maximum value of a radius of curvature of a pressure surface of the outer region.

In this configuration, the inner region has a smaller maximum value of the radius of curvature than the outer region and has a flatter shape. Therefore, the cross-sectional area of the blade can be reduced particularly in the inner region. Accordingly, it is possible to reduce the weight of the blade while suppressing an increase in volume.

(3) In the propeller fan, preferably, the pressure surface of the inner region and the pressure surface of the outer region include concave curved surfaces.

In this configuration, since both the pressure surface of the inner region and the pressure surface of the outer region include concave curved surfaces, the effect of guiding the air flowing along the pressure surface in the respective regions to the circumferential direction can be further enhanced.

Furthermore, in the case where the two configurations (2) and (3) above are provided, the following effects can be obtained. That is, at this time, the maximum value of the pressure surface in the outer region is smaller than the maximum value of the pressure surface in the inner region, and the pressure surfaces in these regions all include concave curved surfaces. The pressure gradient between the pressure surface and the negative pressure surface of the outer region close to the outer periphery is large. Therefore, setting the radius of curvature small can further enhance the effect of guiding the air flowing along the pressure surface of the outer region in the circumferential direction. As a result, the occurrence of leakage flow is further suppressed on the entire pressure surface.

(4) In the above-mentioned propeller fan, a configuration is exemplified in which one concave curved surface is provided in each of the inner region and the outer region, and one peak of the outlet angle also exists.

(5) In the above-mentioned propeller fan, it is preferable that, on the trailing edge of the blade, a concave portion recessed toward the front edge is provided in a region including the position representing the root mean square radius.

In this structure, since the concave portion is provided in the region including the position representing the root mean square radius of the trailing edge portion where the pressure rise is the largest, the pressure rise is reduced in the vicinity of the concave portion. According to this, the air flowing from the leading edge to the trailing edge flows toward the hub side and the outer peripheral portion so as to avoid the position representing the root-mean-square radius in the vicinity of the trailing edge, so that the efficiency of directing the airflow in the circumferential direction can be further improved. Effect.

(6) The air conditioner of this invention is provided with the said propeller fan. Therefore, noise is suppressed in the air conditioner.

Symbol Description

1 outdoor unit

2 shells

3 Outdoor heat exchanger

4 propeller fans

5 motors

6 bell mouth

7 outlet

8 axial flow blower

11 hub

12 blades

12A inner area

12B outer area

13 Inner peripheral part

14 leading edge

15 trailing edge

16 Perimeter

17 bending part

18 Outer peripheral edge

19 concave

19a bottom

21 pressure side

21A Inboard pressure side

21B Outer pressure side

22 Negative pressure side

A0 Rotary axis

D direction of rotation

Rr represents the root mean square radius position

θ exit angle

Claims (5)

1. A kind of propeller fan, possesses blade hub (11) and the blade (12) that is connected with described blade hub (11), it is characterized in that: The blade (12) is shaped to have a peak of the exit angle (θ) of the trailing edge portion (15) at an outer region (12B) radially outer than a representative root mean square radius position (Rr), and , also has a peak value of the outlet angle (θ) of the trailing edge portion (15) in the inner region (12A) located radially inner than the representative root mean square radius position (Rr), The outlet angle (θ) of the trailing edge portion (15) is the tangent line (L3) tangent to the pressure surface (21) at the trailing edge portion (15) when cutting the blade (12) in the circumferential direction and the line (L4) perpendicular to the axis of rotation (A0) of the propeller fan, The representative root mean square radius position (Rr) is calculated using the following formula represented by the representative radius R of the blade (12) and the representative radius r of the hub (11): Represents the root mean square radius position Rr=((R ² +r ² )/2) ⁰ _. ⁵ , Under the condition that the outer diameter of the blade (12) is constant in the direction of the axis of rotation, the representative radius R of the blade (12) is 1/2 of the outer diameter of the blade (12), (12) In the case where the outer diameter of the blade (12) is not constant in the direction of the axis of rotation, the representative radius R of the blade (12) is the average value of the minimum blade radius R1 and the maximum blade radius R2, In the case that the outer diameter of the hub (11) is constant in the direction of the axis of rotation, the representative radius r of the hub (11) is one-half of the outer diameter of the hub (11). When the outer diameter of the hub (11) is not constant in the direction of the axis of rotation, the representative radius r of the hub (11) is the average value of the minimum hub radius r1 and the maximum hub radius r2, The maximum value of the radius of curvature of the pressure surface (21) of the inner region (12A) is greater than the maximum value of the radius of curvature of the pressure surface (21) of the outer region (12B). 2. The propeller fan according to claim 1, characterized in that: The pressure surface (21) of the inner region (12A) and the pressure surface (21) of the outer region (12B) comprise concave curved surfaces. 3. The propeller fan according to claim 1, characterized in that: Each of the inner region (12A) and the outer region (12B) is provided with a concave curved surface, and there is also a peak of the outlet angle (θ). 4. The propeller fan according to any one of claims 1 to 3, characterized in that: On the trailing edge (15) of the blade (12), a recess (19) recessed toward the front edge is provided in a region including the representative root mean square radius position (Rr). 5. An air conditioner, characterized in that it comprises: The propeller fan (4) according to any one of claims 1 to 3.