JP2007024004A - Axial fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bent portion (curved portion or bent portion) toward the suction surface side on the outer periphery of a blade of an axial fan, which is effective for suppressing blade tip vortex, but greatly contributes to the pressure boosting work of the fan. The warpage of the wing is reduced, and the pressure increase is reduced. Solve this.
SOLUTION: In an axial fan in which the outer circumferences of a plurality of blades 13, 13, 13 provided on a hub 14 are bent to the negative pressure surface 13e side, the blown-out air speed is large and the pressure boosting work is most effective. A convex shape projecting in a direction opposite to the rotation direction of the blade 13 beyond the straight line L that connects the rear edge hub end of the blade 13 and the outer peripheral end of the rear edge. Part 13f was formed.
In this way, when the blower wind speed of the trailing edge portion 13b of the blade 13 is large and the radial direction portion where the pressure increasing work can be most effectively performed is a convex portion in the counter-rotating direction, the blade area is enlarged, and the outer peripheral portion is bent. Therefore, the warpage becomes loose and the amount of increase in static pressure can be compensated.
[Selection] Figure 3

Description

  The present invention relates to the structure of an axial fan such as a propeller fan.

  For example, an axial fan such as a propeller fan is generally used as a blower for an outdoor unit for an air conditioner. An example of the configuration of an outdoor unit for an air conditioner that employs an axial fan such as a propeller fan as a blower unit is shown in FIG.

  That is, as shown in FIG. 6, the outdoor unit for the air conditioner includes a propeller fan 4 that is an example of an axial flow fan, and a rear side of the propeller fan 4 that is located on the outer peripheral side of the propeller fan 4. A blower unit 3 is constituted by a bell mouth 5 that partitions the suction area X and the front blowing area Y and a fan guard 6 located on the blowing side (front side) of the propeller fan 4. In the main body casing 1 of the mold, the rear air inlet 10a side heat exchanger 2 is disposed downstream of the air flow. Reference numeral 12 denotes a fan motor that rotationally drives the propeller fan 4, and is supported and fixed to a fan motor mounting bracket (not shown) that is provided on the downstream side of the heat exchanger 2.

  The propeller fan 4 is connected and fixed to the drive shaft 12a of the fan motor 12. For example, as shown in enlarged views in FIGS. 7 and 8, the hub 14 serving as the rotation center of the propeller fan 4 and the hub 14 is composed of a plurality of blades 13, 13, 13 provided integrally on the outer peripheral surface of 14.

  In the case of an outdoor unit having such a structure, in addition to the noise from the propeller fan 4 alone, the noise generated by the blown airflow from the propeller fan 4 colliding with a downstream structure such as the fan guard 6 is the cause. Therefore, there is a problem that the noise during driving becomes high.

  Therefore, in order to reduce the total noise when the axial fan such as the propeller fan 4 is used as the blower of the outdoor unit for the air conditioner as described above, for example, the blade surface shape of the propeller fan blade has been used so far. Measures such as optimization and airfoil wing with excellent aerodynamic performance have been studied. However, these silent methods alone cannot solve the following problems.

  That is, for example, in the blade structure of the propeller fan 4 as shown in FIGS. 7 and 8, when the blades 13, 13, 13 are rotated, as shown in FIG. 8, on the outer peripheral side of the blades 13, 13, 13, An air flow (A) that circulates from the high pressure surface 13d side to the low pressure negative surface 13e side is generated, and a blade tip vortex (B) as shown in the figure is formed by the air flow (A). Then, in the vicinity of the outer periphery of the blades 13, 13, 13, the turbulence of the discharge airflow due to the blade tip vortex (b) generated by the airflow (b) flowing from the discharge side to the suction side is shown in FIGS. 9 and 10, for example. As shown in the figure, the layers are stacked and gradually grow and increase toward the downstream side, and eventually, the pressure surfaces 13d and 13d of the adjacent blades 13, 13, and 13 and the bell mouth are separated from the negative pressure surface 13e of the blades 13, 13, and 13 5 interferes with the inner peripheral surface of 5 or the fan guard 6 which is a structure downstream of the blower, and further increases noise.

  In particular, as shown in FIG. 10, the blade tip vortex (b) away from the suction surface 13 e of the blades 13, 13, 13 interferes with the subsequent blades 13, 13, 13, resulting in further disturbance. An even larger noise is generated on the downstream side of the blower.

  Such a phenomenon is because, for example, if the blade chord length of the blades 13, 13, 13 is shortened in order to reduce the weight of the blower (cost reduction), the original cascade effect of the blades 13, 13, 13 is reduced. For example, as shown in FIG. 11, the blade tip vortex (b) is more likely to move away from the suction surface 13 e and interferes with the adjacent blades 13, 13, 13 earlier than in the above case. It becomes easier to increase.

  In this regard, for example, as shown in FIGS. 12 and 13, the entire outer peripheral portion 13 c from the front edge 13 a side to the rear edge 13 b side of the blades 13, 13, 13 is bent to the suction surface side (suction side). There is one in which the radial width of the bent portion 13c is gradually increased from the front edge 13a side to the rear edge 13b side (for example, see Patent Document 1).

  According to such a configuration, for example, as shown in FIGS. 13 and 14, the air flow (b) on the pressure surface 13 d side of the blades 13, 13, 13 is a convex arc surface on the outer peripheral end side of the blades 13, 13, 13. The outer surface of the blades 13, 13, 13 smoothly wraps around the negative pressure surface 13e on the outer circumferential end side along the pressure surface 13d, and the vortex diameter becomes small and stable. The flow of airflow (c) in the outer circumferential direction of the blades 13, 13, and 13 in the blade no longer interferes with the blade tip vortex (b).

  Then, as described above, when the width of the bent portion 13c of the blade outer peripheral end portion 13c gradually increases from the vicinity of the front edge 13a to the vicinity of the rear edge 13b of the blades 13, 13, 13 as described above, 13 from the front edge 13a side to the rear edge 13b side, corresponding to the vortex diameter of the blade tip vortex (b) gradually developing and expanding the vortex diameter, smoothly from the front edge 13a side to the rear edge 13b side The blade tip vortex (b) generated is less likely to be separated from the blade suction surface 13e.

  Therefore, for example, when the blade chord length is shortened to reduce the weight of the blades 13, 13, 13, the blade tip vortex (b) does not interfere with each other between the adjacent blades 13, 13, 13, Disturbances in the air flow at the downstream side of the blower are also reduced.

  As a result, noise when incorporated in an outdoor unit for an air conditioner is also effectively reduced.

Japanese Patent No. 3629702 (Specification, page 1-17, Fig. 1-27)

  However, as described above, when the bent portion (curved portion or bent portion) 13c toward the suction surface side is provided on the outer periphery of the blade 13, it is effective for suppressing the blade tip vortex (b) itself. Does not contribute.

  As a result, there is a problem that the blade warpage that greatly contributes to the boosting work of the fan is reduced, and the boosting amount is reduced.

  Therefore, it is a minus to increase the width of the bent portion 13c more than necessary. Therefore, in the above-described conventional example, the front-rear length of the outer peripheral edge of the blade within a range of, for example, 15% or less of the length from the rotation center of the blade 13 to the outer peripheral edge in the radial direction at least at the maximum width portion near the trailing edge 13b. It is said that it is preferable to set the change width according to the thickness.

  However, even if such an optimum width is selected, a certain amount of increase in the boost amount is unavoidable.

  By the way, the rear edge portion 13b of the blade 13 of the conventional propeller fan as shown in FIGS. 12 and 13 is entirely bent in an arc shape from the hub 14 side to the outer peripheral end as shown in FIG. When viewed from the direction of the rotation center axis O of the vehicle, the radial center portion of the trailing edge portion 13b is rotated by the rotation of the blade 13 rather than the straight line L connecting the trailing edge hub end and the trailing edge outer peripheral end of the blade 13. It is formed in the convex part which protruded shallowly and widely in the reverse direction.

  As a result, the wing area is secured widely.

  However, from various examinations, the blade 13 has the largest blown wind speed, for example, in the chord line region near the outer circumference indicated by FF ′ in FIG. Unless the wing area is enlarged, it does not contribute to the increase of the pressure increase.

  Accordingly, as shown in FIG. 15, the rear edge 13 b of the rear edge 13 b as viewed from the hub 14 side of the rear edge 13 b toward the outer peripheral end as viewed from the rotation center axis O direction of the fan impeller, Even if the convex shape exceeds the straight line L connecting the outer peripheral end side, the amount of pressure increase does not increase effectively for the expansion of the blade area, but contrary to the weight reduction of the impeller and the reduction of the amount of blade material. It will be.

  The present invention has been made to solve such a problem. In a propeller fan in which the outer peripheral portion of a blade is bent to the suction surface side from the front edge side to the rear edge side, the blowout wind speed is large and the pressure is increased. Convex projecting in the direction opposite to the rotation direction of the blade beyond the straight line connecting the rear edge hub end side of the blade and the outer peripheral end side of the rear edge, the radial portion of the blade trailing edge that can work most effectively It is an object of the present invention to provide a high-performance axial fan that can compensate for the decrease in the amount of increase in static pressure caused by bending the outer periphery of the blade by forming the outer periphery of the blade. .

  In order to achieve the same object, the present invention comprises the following effective problem solving means.

(1) Invention of Claim 1 An axial fan according to the present invention is an axial fan in which the outer periphery of a plurality of blades 13, 13, 13 provided on the hub 14 is bent toward the negative pressure surface 13 e, respectively. The radial direction portion of the blade trailing edge portion 13b where the blowing air speed is large and pressure boosting work can be most effectively performed is beyond the straight line L connecting the trailing edge hub end and the trailing edge outer peripheral end of the blade 13 It is characterized in that it is formed in a convex portion 13f protruding in the direction opposite to the rotational direction of 13.

  As described above, when the outer peripheral portions of the plurality of blades 13, 13, 13 are bent toward the negative pressure surface 13 e, the airflow (A) on the pressure surface 13 d side of the blades 13, 13, 13 is generated. The blades 13, 13, 13 smoothly wrap around the outer circumferential end side concave arcuate negative pressure surface 13 e along the outer circumferential end side convex arcuate pressure surface 13 d.

As a result, the vortex diameter becomes small and stable, and the flow of airflow (c) toward the outer periphery of the blade 13 on the suction surface 13e side does not interfere with the blade tip vortex (b).

  In that case, the radial direction portions where the blowing air speed of the trailing edge portion 13b of the blades 13, 13, 13 is large and the pressure increasing work can be most effectively performed are the trailing edge hub end side and the trailing edge outer peripheral end. When the blade area is enlarged by forming a convex portion that protrudes in the direction opposite to the rotational direction beyond the straight line L connecting the sides, the outer periphery is bent toward the suction surface 13e as described above, and warpage occurs. It is possible to effectively compensate for the shortage of the static pressure increase amount that has become loose and the static pressure increase amount has decreased.

  As a result, it is possible to reduce the blowing sound and increase the efficiency of the blowing performance.

(2) Invention of Claim 2 In the axial fan of this invention, in the configuration of the invention of Claim 1, the bent portion 13c to the suction surface side is the entire from the front edge 13a of the blade 13 to the rear edge 13b. It is characterized by the fact that it is provided over the distance.

  According to such a configuration, since the entire outer peripheral portion from the front edge 13a side to the rear edge 13b side of the blade 13 is first bent to the negative pressure surface 13e side, the air flow on the pressure surface 13d side of the blade 13 (A) smoothly wraps around the outer peripheral end side concave negative pressure surface 13e of the blade 13 along the outer peripheral end side convex pressure surface 13d of the blade 13, and the vortex diameter is small and stable. Thus, the flow of airflow (c) toward the outer periphery of the blade 13 on the suction surface 13e side does not interfere with the blade tip vortex (b).

  In that case, the radial direction portions where the blowing air speed of the trailing edge portion 13b of the blades 13, 13, 13 is large and the pressure increasing work can be most effectively performed are the trailing edge hub end side and the trailing edge outer peripheral end. When the blade area is enlarged by forming a convex portion protruding in the direction opposite to the rotation direction beyond the straight line L connecting the sides, the entire outer peripheral portion is warped by bending toward the suction surface 13e as described above. It is possible to effectively compensate for the deficiency of the static pressure increase amount, which has been reduced and the static pressure increase amount has decreased.

  As a result, it is possible to reduce the blowing sound and increase the efficiency of the blowing performance.

(3) Invention of Claim 3 In the axial fan of this invention, in the configuration of the invention of Claim 1, the bent portion 13c to the suction surface side reaches from the front edge 13a of the blade 13 to the rear edge 13b. It is characterized by being provided from a predetermined position in the middle to the rear edge 13b.

  According to such a configuration, the outer peripheral portion from the predetermined position on the way from the front edge 13a side to the rear edge 13b of the blade 13 to the rear edge 13b is bent toward the negative pressure surface 13e. As in the case of the invention of 2, the air flow (a) on the pressure surface 13d side of the blade 13 smoothly flows along the outer peripheral end-side convex pressure surface 13d of the blade 13 and the outer peripheral end-side concave shape of the blade 13. The vortex diameter becomes small and stable, and the flow of airflow (c) toward the outer periphery of the blade 13 on the negative pressure surface 13e side interferes with the blade tip vortex (b). No longer.

  In that case, the radial direction portions where the blowing air speed of the trailing edge portion 13b of the blades 13, 13, 13 is large and the pressure increasing work can be most effectively performed are the trailing edge hub end side and the trailing edge outer peripheral end. When the blade area is enlarged by forming a convex portion protruding in the direction opposite to the rotation direction beyond the straight line L connecting the sides, the predetermined length portion of the outer peripheral portion is bent toward the negative pressure surface 13e as described above. As a result, the warpage is loosened, and the deficiency of the static pressure increase amount, which has decreased, can be effectively compensated.

  As a result, it is possible to reduce the blowing sound and increase the efficiency of the blowing performance.

(4) Invention of Claim 4 In the axial flow fan of this invention, in the structure of the said invention of Claim 1, 2, or 3, the width of the radial direction of the bending part 13c to the suction surface side is the rear edge 13b side. It is characterized by being formed so large.

  Thus, when the radial width of the bent portion 13c is formed so as to increase toward the rear edge 13b, the blades 13, 13, and 13 gradually increase from the front edge 13a to the rear edge 13b. Corresponding to the vortex diameter of the blade tip vortex (b) whose lamination is increased and the vortex diameter is expanded, the effect of smoothly reducing the vortex diameter from the front edge 13a side to the rear edge 13b side comes to be exhibited. Further, the generated blade tip vortex (b) is unlikely to be separated from the blade suction surface 13e.

  Therefore, for example, even when the chord length is shortened to reduce the weight of the blade 13, the blade tip vortex (b) does not interfere with each other between the adjacent blades 13, 13, and the downstream side of the blower The turbulence of the air flow at the air is also reduced.

  As a result, in the same configuration, the above-described operations are effectively combined, and noise when incorporated in the outdoor unit for an air conditioner is more effectively reduced.

(5) Invention of Claim 5 In the axial fan of this invention, in the structure of the said invention of Claim 1, 2, 3 or 4, it is in the direction opposite to the rotation direction of the most convex part 13f in the blade | wing trailing edge part 13b. The convex radial direction portion has a radius from the rotation center O of the fan impeller as Rt, a radius of the hub 14 as Rh, and an arbitrary position on the radius Rt from the rotation center O of the fan impeller as R, It is characterized in that (R-Rh) / (Rt-Rh) is a portion that is 0.65 to 0.85.

  According to the measurement results of the inventors of the present application, the radial direction portion where the blown-out air speed is the highest and the pressure boosting work can be most effectively performed is the radius from the rotation center O of the fan impeller Rt, the radius of the hub 14 Rh, and the fan blade When an arbitrary position on the radius Rt from the rotation center O of the vehicle is R, the radial position indicated by (R−Rh) / (Rt−Rh) is 0.65 to 0.85. .

  Accordingly, the blade area is expanded as the convex portion 13f protruding in the counter-rotating direction beyond the straight line L connecting the trailing edge hub end side and the trailing edge outer peripheral end side of the blade as described above. To do.

  If it does in this way, curvature will become loose by the curve of an outer peripheral part, and the shortage of the amount of static pressure rise which the amount of static pressure rise fell can be compensated most effectively.

  As a result, according to the axial fan of the present invention, by providing a curved portion on the outer periphery of the blade, the blade tip vortex can be stably generated near the suction surface, and at the trailing edge portion where the blade blowing wind speed becomes maximum. By providing a convex part that protrudes in the counter-rotating direction and effectively expanding the blade area, noise can be reduced without reducing the amount of increase in static pressure even if the curved part exists. ing.

  As a result, it is possible to achieve both reduction of blowing sound and high efficiency of blowing performance.

  Further, since it is not necessary to enlarge the blade area more than necessary, it is not necessary to increase wasteful blade material.

  As a result, the fan impeller is also suitable for the demand for weight reduction (cost reduction).

  1 to 4 show the configuration and operation of an axial fan such as a propeller fan according to the best embodiment of the present invention.

  First, FIGS. 1 to 3 show the basic configuration of a blade of an impeller when the propeller fan 4 is adopted as a coaxial flow fan, and FIG. 4 shows the radial position and blowing of the trailing edge of the blade. The relationship with wind speed is shown respectively.

(Basic configuration of fan impeller)
First, in FIGS. 1 to 3, reference numeral 14 denotes a synthetic resin hub that serves as a rotation center of the propeller fan 4, and a plurality of (three) blades 13, 13, 13 are provided on the outer peripheral surface of the hub 14. It is integrally formed.

  The blades 13, 13, 13 are such that the outer peripheral end of the front edge 13 a and the outer peripheral end of the rear edge 13 b are positioned in front of the inner peripheral end on the hub 14 side in the rotational direction of the blade 13, respectively. As shown in the figure, the outer peripheral end portion is bent toward the suction side with a predetermined width, for example, by being bent or warped from the vicinity of the front edge 13a to the vicinity of the rear edge 13b. The width is gradually enlarged from the front edge 13a side to the rear edge 13b side at a predetermined ratio.

  The radial width of the bent portion 13c is, for example, the maximum width at the trailing edge 13b portion in order to effectively suppress the blade tip vortex (b) without reducing the air blowing performance of the blade 13. It is desirable that the portion has a dimension of, for example, 15% or less of the radial length from the rotation center of the impeller of the propeller fan 4 (that is, the center of the hub 14) to the outer peripheral end of the blade 13.

Further, the rear edge portion 13b of the blades 13, 13, 13 connects the hub end of the rear edge portion 13b of the blade 13 and the outer peripheral end of the rear edge portion 13b when viewed from the direction of the rotation center axis O of the fan. With respect to the straight line L (refer to the broken line in FIG. 3), the blowout wind speed is large, and the radial portion (for example, the outer peripheral line of the diameter φ _{1 to} φ ₅ of the fan impeller in FIG. Region) is formed in a convex portion 13f that protrudes in the direction opposite to the rotation direction M of the blade 13 beyond the straight line L.

  And the radial direction part (maximum convex amount part a in FIG. 3) which protrudes in the reverse direction to the rotational direction M of the convex part 13f in the trailing edge part 13b of the blade 13 is the rotational center O of the fan impeller. (R−Rh) / (Rt−Rh) is 0, where Rt is the radius from Rt, Rh is the radius of the hub 14, and R is an arbitrary position on the radius Rt from the rotation center O of the fan impeller. The portion is 65 to 0.85.

  Now, for example, a conventional propeller fan blade having no bent portion 13c on the outer periphery of the blade 13 as shown in FIGS. 7 and 8, and a bent portion 13c on the outer periphery as shown in FIGS. For each of the blades of the propeller fan provided with the blade speed, the blade blowing air speed between the values (R−Rh) / (Rt−Rh) of 0 to 1.0 was measured and looked as shown in FIG.

  From this measurement result, regardless of whether or not the bent portion 13c is present on the outer periphery of the blade, the radial region in which the maximum wind speed of the blade trailing edge portion 13b is generated is (R−Rh) / (Rt−Rh). The region is approximately 0.65 to 0.85.

In the case of the present embodiment, the bent portion 13f has a range of (R−Rh) / (Rt−Rh) ≈0.9 to 1.0 (fan impeller diameters φ ₅ and φ _{6 in} FIG. 3). Between the outer peripheral lines).

  Therefore, the convex portion 13f has a radius from the rotation center O of the fan impeller as Rt, a radius of the hub 14 as Rh, and an arbitrary position on the radius Rt from the rotation center O of the fan impeller as R. , (R-Rh) / (Rt-Rh) is preferably provided in a portion where 0.65 to 0.85.

And the top position where the protrusion amount a in the counter-rotating direction beyond the straight line L of the convex portion 13f is the maximum is the boundary with the bent portion 13c (the outer periphery of the fan impeller diameter φ _{5 in} FIG. 3). The portion that is radially inward of the line 13 and has the highest blown wind speed of the blade 13, for example, the vicinity of (R−Rh) / (Rt−Rh) ≈0.75 is suitable (see FIG. 4).

  On the other hand, in the conventional example of FIG. 15, the radial position that is most convex in the counter-rotation direction side is set to (R−Rh) / (Rt−Rh) ≈0.5. Since the blowing air speed of the wing portion is small, the increase in static pressure due to the provision of the convex portion is small, and the increase in the wing area at the corner does not function effectively.

(Operation of impeller blades)
As described above, the propeller fan 4 according to the best embodiment of the present invention has the suction surface 13e extending from the front edge 13a side to the rear edge 13b side around the outer periphery of the plurality of blades 13, 13, 13 provided on the hub 14. In the axial fan that is bent to the side, the radial direction portion of the blade trailing edge portion 13b that has the highest blown-out air speed and can perform the pressure increasing work most effectively is defined as the rear edge hub end and the rear edge outer periphery of the blade 13 It is formed in a convex portion 13f that protrudes in the direction opposite to the rotation direction of the blade 13 beyond the straight line L connecting the ends.

  When the outer peripheral portion from the front edge 13a side to the rear edge 13b side of the blade 13 is bent toward the negative pressure surface 13e in this way, the air flow on the pressure surface 13d side of the blade 13 as shown in FIG. (A) smoothly wraps around the outer peripheral end side concave negative pressure surface 13e of the blade 13 along the outer peripheral end side convex pressure surface 13d of the blade 13, and the vortex diameter is small and stable. Thus, the flow of airflow (c) toward the outer periphery of the blade 13 on the suction surface 13e side does not interfere with the blade tip vortex (b).

  In this case, as shown in FIGS. 1 to 3, the radial direction portion where the blowing air speed of the trailing edge portion 13 b of the blade 13 is large and the pressure increasing work can be most effectively performed is the rear edge portion hub end of the blade 13. When the blade area is enlarged as a convex portion 13f that protrudes in a direction opposite to the rotation direction of the blade 13 beyond the straight line L that connects the outer peripheral end of the trailing edge portion, the outer peripheral portion is arranged on the suction surface 13e side as described above. As a result of the bending, the warp is loosened, and the deficiency of the static pressure increase amount that the static pressure increase amount is reduced can be effectively compensated.

  As a result, it is possible to reduce the blowing sound and increase the efficiency of the blowing performance.

  Moreover, in that case, the radial width of the bent portion 13c from the front edge 13a side to the rear edge 13b side of the outer periphery of the blade is formed to be larger toward the rear edge 13b side.

  In this way, when the radial width of the bent portion 13c is formed so as to increase from the vicinity of the front edge 13a to the rear edge 13b side, from the front edge 13a side to the rear edge 13b side of the blade 13, Corresponding to the vortex diameter of the tip vortex (b) that is gradually increased in lamination and expanded, the vortex diameter reduction effect is smoothly exhibited from the front edge 13a side to the rear edge 13b side, Further, the generated blade tip vortex (b) is unlikely to be separated from the blade suction surface 13e.

  Therefore, for example, even when the chord length is shortened to reduce the weight of the blade 13, the blade tip vortex (b) does not interfere with each other between the adjacent blades 13, 13, and the downstream side of the blower The turbulence of the air flow at the air is also reduced.

  As a result, in the same configuration, the above-described operations are effectively combined, and noise when incorporated in the outdoor unit for an air conditioner is more effectively reduced.

  Furthermore, in the axial fan of this embodiment, the radial direction portion that is most convex in the direction opposite to the blade rotation direction of the convex portion 13f of the rear edge portion 13b of the blade 13 is shown in FIG. When the radius from the rotation center O of the impeller is Rt, the radius of the hub 14 is Rh, and an arbitrary position on the radius Rt from the rotation center O of the fan impeller is R, (R−Rh) / (Rt− Rh) is set to be 0.65 to 0.85.

  In the blades 13, 13, 13 of the propeller fan 4 as described above, the radial direction portion where the blowing wind speed is large and the pressure increasing work can be most effectively performed is (R−Rh) / (Rt−Rh) being 0 as described above. .65 to 0.85 (see FIG. 4). Therefore, the area of the blade is effectively enlarged by enlarging the portion in a convex shape in the counter-rotating direction.

  As a result, the warpage is loosened by the bending of the outer peripheral portion, and it is possible to effectively compensate for the shortage of the static pressure increase amount in which the static pressure increase amount has decreased.

  As a result of the above, according to the axial fan of this embodiment, by providing the curved portion on the outer periphery of the blade, the blade tip vortex is stably generated near the suction surface, and the trailing edge that maximizes the blade blowing air speed is obtained. By providing a convex portion in the counter-rotating direction at the portion to increase the blade area, noise can be reduced without reducing the amount of increase in static pressure even if the bent portion exists.

  As a result, it is possible to achieve both reduction of blowing sound and high efficiency of blowing performance.

  Further, since it is not necessary to enlarge the blade area more than necessary, it is not necessary to increase wasteful blade material.

  As a result, the fan impeller is also suitable for the demand for weight reduction (cost reduction).

(Modification)
Next, FIG. 5 shows a configuration of a blade portion of an impeller of a propeller fan according to a modification of the best embodiment of the present invention.

  In this example, the bent portion 13c to the suction surface side provided over the whole of the outer periphery of the blade 13 from the front edge 13a to the rear edge 13b in the best embodiment is not the entire blade outer peripheral portion. It is provided over a range from a predetermined position (for example, a position approaching the rear edge 13b side by about 25% from the front edge 13a side) to the rear edge 13b on the way from the front edge 13a to the rear edge 13b on the outer periphery of the blade. It is said.

  Also in such a configuration, first, a portion from a predetermined position in the middle of the outer periphery of the blade 13 from the front edge 13a side to the rear edge 13b side to the rear edge portion 13b is similarly bent to the negative pressure surface 13e side. Therefore, the air flow (b) on the pressure surface 13d side of the blade 13 is also smoothly formed on the outer peripheral end side concave surface of the blade 13 along the outer peripheral end convex pressure surface 13d of the blade 13 as shown in FIG. , And the vortex diameter is small and stable.

  As a result, the flow of airflow (c) toward the outer periphery of the blade 13 on the suction surface 13e side does not interfere with the blade tip vortex (b).

  In that case, as shown in the figure, the radial direction portion where the blowing air speed of the trailing edge portion 13b of the blades 13, 13, 13 is large and the pressure increasing work can be most effectively performed is the blade trailing edge hub end side. When the blade area is enlarged by forming a convex portion that protrudes in the direction opposite to the rotation direction beyond the straight line L connecting the outer peripheral end side of the rear edge portion, the outer peripheral portion is bent toward the negative pressure surface 13e as described above. As a result, the warpage is loosened, and the deficiency of the static pressure increase amount, which has decreased, can be effectively compensated.

  As a result, it is possible to reduce the blowing sound and increase the efficiency of the blowing performance.

(About types of feathers)
In the above embodiments and modifications, the case of a blade having a thin blade structure has been described.

  However, the application object of the invention of this application is not limited to the case of such a thin blade structure, for example, a general thick blade and a thick blade, and various airfoil blades having further improved aerodynamic performance. Needless to say, it can be adopted in the same manner.

It is a rear view of the propeller fan which concerns on the best embodiment of this invention. It is a perspective view of the impeller part of the same propeller fan. It is a rear view of the impeller part of the same propeller fan. It is a graph which shows the relationship between the position of the radial direction of the rear edge part of the blade | wing of the impeller part of the same propeller fan, and the blowing wind speed. It is a top view which shows the shape of the principal part of the blade | wing which concerns on the modification of the best embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the outdoor unit for air conditioners which employ | adopted the conventional general propeller fan. It is a rear view of the impeller of the conventional general propeller fan employ | adopted with the outdoor unit. It is sectional drawing which shows the cross-section of the blade | wing part of the conventional general propeller fan, and the effect | action (problem) of the principal part. It is a schematic explanatory drawing which shows the problem (blade tip vortex generating mechanism) in the relationship with the structure of the outdoor unit by the conventional general propeller fan. It is a schematic explanatory drawing which shows the blade edge vortex interference phenomenon between the adjacent blades of the blade | wing of the same general propeller fan. It is a schematic explanatory drawing which shows the wing tip vortex interference state between adjacent blades in the case where the chord length of the blade of the conventional general propeller fan is shortened. It is a perspective view which shows the basic shape of the blade | wing of the propeller fan which concerns on the conventional example which addressed the problem of FIGS. 8-11. It is sectional drawing which shows the blade tip vortex suppression effect | action of the blade | wing of the propeller fan of the prior art example. It is explanatory drawing which shows the effect | action between the adjacent blades of the blade | wing of the propeller fan of the prior art example. It is explanatory drawing which shows the new problem of the blade | wing of the propeller fan of the prior art example.

Explanation of symbols

  1 is a main body casing, 2 is a heat exchanger, 3 is a blower unit, 4 is a propeller fan, 5 is a bell mouth, 6 is a fan guard, 8 is a heat exchanger, 13 is a blade, 13a is a front edge, 13b is a rear edge , 13c are bent portions, 13d is a pressure surface, 13e is a negative pressure surface, 13f is a convex portion of the blade trailing edge 13b, and 14 is a hub.

Claims (5)

  In the axial flow fan in which the outer periphery of the plurality of blades (13), (13), (13) provided on the hub (14) is bent to the negative pressure surface (13e) side, the blowout wind speed is large, The radial direction portion of the blade trailing edge (13b) capable of performing pressure increasing work most effectively exceeds the straight line L connecting the trailing edge hub end and the trailing edge outer peripheral end of the blade (13). The axial flow fan is characterized in that it is formed in a convex portion (13f) projecting in the direction opposite to the rotation direction.   The axial flow fan according to claim 1, wherein the bent portion (13c) toward the suction surface side is provided from the front edge (13a) to the rear edge (13b) of the blade (13). .   The bent portion (13c) to the suction surface side is provided from a predetermined position on the way from the front edge (13a) to the rear edge (13b) of the blade (13) to the rear edge (13b). The axial fan according to claim 1.   The axial fan according to claim 1, 2 or 3, wherein a width in the radial direction of the bent portion (13c) toward the suction surface is formed larger toward the rear edge (13b).   The radial portion of the blade trailing edge (13b) that protrudes most in the direction opposite to the rotational direction of the convex portion (13f) has a radius from the rotation center O of the fan impeller as Rt and a radius of the hub (14). Rh, when R is an arbitrary position on the radius Rt from the rotation center O of the fan impeller, R (R-Rh) / (Rt-Rh) is a portion where 0.65 to 0.85. The axial fan according to claim 1, 2, 3, or 4, characterized by the above.

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