JP5366532B2 - Axial fan and air conditioner outdoor unit - Google Patents

Description

  The present invention relates to an axial fan and an outdoor unit of an air conditioner, and more particularly to an axial fan having a blade cross-sectional shape having a curved shape and an outdoor unit of an air conditioner including the axial fan.

  The blade cross-sectional shape of an axial fan (also called a propeller fan) includes a thick blade type with completely different shapes on the pressure surface side and suction surface side, and a thin blade type with a substantially equal shape on the pressure surface side and suction surface side. There are two types. The blade cross-sectional shape of an axial fan made of resin molding or sheet metal is generally a thin blade type. As a blade cross-sectional shape of this thin blade type axial flow fan, a single arc blade using one arc is generally used (see Patent Document 1).

In addition, an axial fan having a composite arc blade that combines two or more arcs has been proposed (see Patent Document 2).
JP 2004-332673 A JP 2004-124748 A

  To simplify the principle of the blades of an axial fan, the axial fan deflects the rotational speed in the direction of the blade's inclination to create the wind in the axial direction. It can be said that it can be converted. However, in a flat blade with a single angle, the entry angle at the leading edge of the blade increases, so the air resistance at the leading edge of the blade increases, and the flow flows along the surface on the suction surface side of the blade. This causes a separation phenomenon that does not flow, greatly reducing the efficiency of the axial fan and causing a large fluid noise.

  Therefore, if the blade is swollen to the suction side such as an arc, the above contradiction can be alleviated, but it is related to the problem of blade height, which is a problem during actual device design, and constraints such as the upper limit of the motor speed. There are the following problems.

(1) In the axial fan of the arc blade having a small radius of curvature, the blade height in the section along the rotation direction of the blade increases when the flow entry angle on the front edge side is reduced. Since the end angle on the trailing edge side is increased as much as the arc is drawn, and the rotation angle is increased to be converted into the axial wind speed, a large air volume can be obtained even at a low rotation speed. However, since the radius of curvature is small, the air flow is easily separated on the suction surface side of the blade, and a large fluid noise is generated, which reduces the efficiency of the axial fan. In addition, unless the wings are shortened, a compact design cannot be achieved in the wing height direction, so the balance must be achieved.

(2) An axial fan with an arc blade having a large radius of curvature can be designed with a reduced blade height in the cross section along the blade's rotational direction, and with less flow separation on the suction surface side of the blade. However, since the terminal angle on the trailing edge side is small, a large air volume cannot be obtained unless the rotational speed is increased.

  Therefore, recently, it has been sought to achieve a balance by using a composite arc blade combining two or more arcs as shown in Patent Document 2, but the air volume without a high rotation at a low blade height. The fan efficiency cannot be increased with low noise.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the air flow without reducing the blade height and high rotation, and to improve fan efficiency with low noise. And providing an outdoor unit of an air conditioner.

An axial fan according to the present invention is an axial fan in which a plurality of blades are integrally formed around a hub, and the blade is cut when the blade is cut by a cylindrical surface centered on the center of the hub . The cross-sectional shape along the rotation direction has three or more bulging portions that bulge to the suction surface side of the blade and bulge portions that bulge to the pressure surface side of the blade. A line that equally divides the bulging portion that bulges to the side and the bulging portion that bulges to the pressure surface side is a neutral line of the wing, and the bulging portion is a distance from the neutral line of the wing Is formed so as to increase from the leading edge of the wing toward the trailing edge of the wing.

  Further, in the axial fan according to the present invention, when the number of bulging portions is an odd number, the bulging portion on the front edge side is used as a bulging portion that bulges to the suction surface side, and the bulging portion When the number is an even number, the bulging portion on the front edge side is a bulging portion that bulges to the pressure surface side.

  An outdoor unit of an air conditioner according to the present invention includes a compressor, an outdoor heat exchanger, and an axial fan configured as described above for blowing air to the outdoor heat exchanger in an outdoor unit body. To do.

  According to the present invention, it is possible to provide an axial fan and an outdoor unit for an air conditioner that can improve the air volume without increasing the rotation speed with a low blade height, and can increase fan efficiency with low noise.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a horizontal sectional view showing a preferred embodiment of an outdoor unit of an air conditioner including an axial fan according to the present invention.

  The outdoor unit 11 of the air conditioner shown in FIG. 1 includes an outdoor unit main body 12, and the outdoor unit main body 12 is provided with a suction port 12a, a blowout port 12b, and a bell mouth 12c. In the outdoor unit body 12, a heat exchanger 1 as an outdoor heat exchanger, an axial fan 20 that blows air to the heat exchanger 1, and a compressor 14 that compresses the refrigerant are housed.

  An axial fan 20 shown in FIG. 1 is attached to the output shaft 16 of the motor 15. When the motor 15 is driven and the axial fan 20 rotates, outdoor air is introduced from the suction port 12a along the T direction, and heat is exchanged through the heat exchanger 1, and then from the blowout port 12b. To be released. The axial fan 20 is made of resin molding or sheet metal.

  FIG. 2 is a front view of the axial fan 20 shown in FIG. 1 as viewed from the S direction, in which the suction surface of the blade is visible.

  The axial fan 20 shown in FIG. 2 is also called a propeller fan and continuously rotates in the R direction. The axial fan 20 has three blades 21 and a central hub 22, and each blade 21 has the same shape. The hub 22 is attached to the output shaft 16 of the motor 15 shown in FIG. The three blades 21 are formed so as to protrude in the radial direction at a distance of 120 degrees with respect to the hub 22. Each blade 21 has a front edge portion 31, a rear edge portion 32, and an outer peripheral portion 33. In FIG. 2, in each blade 21, the cylindrical cut surface 35 is drawn around the center CL of the hub 22 by a broken line. In addition, a circle 36 including the outer peripheral portion 33 is drawn with the solid line as the center CL of the hub 22.

  FIG. 3 is a cross-sectional view showing an example of the shape of the wing along the line AA along the cylindrical cut surface 35 of each wing 21 shown in FIG.

  FIG. 3 shows the front edge portion 31, the rear edge portion 32, and the bulging portions 51, 52, 53 of the wing 21, and the front edge portion 31, the bulging portions 51, 52, 53, and the rear edge portion. Along the cross section 32, one neutral line 40 and undulation vertex lines 41 and 42 indicating the expansion state of two undulation vertices (amplitude) are drawn. The bulging portions 51, 52, and 53 are also called undulating convex portions.

  The blade 21 shown in FIG. 3 has a pressure surface side 61 and a suction surface side 62. The neutral line 40 passes through the center of the cross section of the wing 21, and the wing 21 has three bulging portions 51, 52, 53 across the neutral line 40. The bulging portion 51 has a undulating vertex height H1 with respect to the neutral line 40. Similarly, the bulging portion 52 has a undulating vertex height H2 with respect to the neutral line 40, and the bulging portion 53 has an undulating vertex height H3 with respect to the neutral line 40. The bulging portion 52 is in contact with the undulating vertex line 41, and the bulging portions 51 and 53 are in contact with the undulating vertex line 42.

  The magnitude relationship between the undulating vertices H1, H2, and H3 shown in FIG. 3 is H1 <H2 <H3, and the undulating vertex lines 41 and 42 reach the bulging portions 51, 52, and 53 with the neutral line 40 as the center. Has spread according to. As shown in FIG. 3, the cross-sectional shapes of the three bulging portions 51, 52, and 53 of the blades 21 of the axial fan are undulations that protrude alternately in the opposite direction with respect to the neutral line 40. In such a wavy curved shape in the cross section, as shown by the undulating vertex lines 41, 42, the vertex positions of the bulged portions 51, 52, 53 of the curve, the so-called amplitude, are rearward from the leading edge portion 31 of the blade 21. As it goes to the edge 32, it becomes larger. That is, by sandwiching the curved bulging portions 51, 52, 53 between the undulating vertex lines 41, 42, it is possible to prevent the air boundary layer from becoming thicker toward the downstream side on the suction surface side 62. .

  4 is a cross-sectional view showing the shape and rotation direction R of blade 21 shown in FIG. 3 according to the embodiment of the present invention. FIG. 4 shows the blade height M of the blade 21, the rotational axis direction flow velocity component N, the wind speed vector V immediately after blowing, and the rotational direction R.

  FIG. 5A shows a cross-sectional shape of the blade 21 according to the embodiment of the present invention shown in FIG. 4, and FIG. 5B shows a comparative example in which the rush angle and the terminal angle are those of the embodiment of the present invention. The cross-sectional shape of a single blade in the case of being equivalent to the blade 21 is shown.

  In the blade 21 shown in FIG. 5A, while reducing the blade height M shown in FIG. 4, the rush angle θ1 on the front edge portion 31 side can be reduced to reduce the air resistance, and the rear edge portion 32 side can be reduced. It is possible to increase the air volume by increasing the terminal angle θ2. Further, as shown in FIG. 4, since the air flow C flows along the blade 21, the angle θ <b> 3 at which the separation of air starts as shown in FIG. 5A without causing a large separation of the air flow. The position is a position P1 closer to the rear edge portion 32. For this reason, noise is reduced and fan efficiency is increased. That is, the rotational axis direction flow velocity component N and the wind speed vector V immediately after blowing can be increased, and the air volume is increased. As described above, the vane 21 of the axial fan can improve the air volume without increasing the rotation at a low blade height M, and thus can increase fan efficiency with low noise.

    On the other hand, in the comparative example shown in FIG. 5B, the entry angle θ1 and the end angle θ2 of the blade 200 are equivalent to the entry angle θ1 and the end angle θ2 of the blade 21 shown in FIG. , A single arc or a compound arc (the direction of the convex is the same). Therefore, as compared with the blade 21 shown in FIG. 5A, the flow separation start angle θ4 is away from the rear edge portion of the blade 200 and closer to the front edge portion, so that noise increases and fan efficiency decreases. To do.

  Next, FIG. 6A shows a cross-sectional shape of the blade 21 of the embodiment of the present invention shown in FIG. 4, and FIG. The cross-sectional shape in the same case from the front edge part to the rear edge part is shown.

  In the wing 21 according to the embodiment of the present invention shown in FIG. 6 (A), as already described, the wavy curved line shape in the cross section has the bulge portions 51, The vertex positions of 52 and 53, so-called amplitudes, increase from the leading edge 31 to the trailing edge 32 of the wing 21.

  On the other hand, in the wing 300 of the comparative example shown in FIG. 6B, the two undulating vertex lines 301 and 302 are parallel to the neutral line 303. For this reason, the entry angle θ6 is larger than the entry angle θ1, and the air resistance is increased. On the other hand, in the blade 300 of the comparative example, the terminal angle θ7 is smaller than the terminal angle θ2, so the air volume cannot be increased so much.

  Next, still another embodiment of the present invention will be described with reference to FIGS. In another embodiment of the present invention described below, the same parts as those in the embodiment shown in FIG.

  In the embodiment of the present invention shown in FIG. 7, unlike the embodiments of the present invention so far, the neutral line of the wing 21 is a curved neutral line 40P. In the embodiment of FIG. 8, the neutral line of the wing 21 is a broken line neutral line 40R. Thus, the neutral line may be a curved line or a broken line.

  In the embodiment of the present invention shown in FIG. 9, four bulging portions 59, 51, 52, 53 are formed on the blade 21. In this way, when four (even) bulging portions 59, 51, 52, 53 are formed, the bulging portion 53 at the final position is formed so as to protrude toward the suction side 12 side. Must have been. Therefore, when the four (even) bulging portions 59, 51, 52, 53 are formed, the first bulging portion 59 of the front edge portion 31 is convex toward the pressure surface side 61. Is formed.

  In the embodiment of the present invention shown in FIG. 10, five bulging portions 58, 59, 51, 52, 53 are formed on the wing 21. Thus, when five (odd) bulging portions 58, 59, 51, 52, 53 are formed, the first bulging portion 58 of the front edge portion 31 is located on the suction surface side 62. It is formed to be convex. As shown in FIG. 9 and FIG. 10, the same effect is obtained by determining the direction in which the first bulging portion of the front edge portion 31 is convex depending on whether the bulging portion is even or odd. be able to.

  A blade 21 of the embodiment shown in FIG. 11 is a modification of the blade 21 shown in FIG.

  The blade 21 in FIG. 11A is configured by combining three arcs 71, 72, 73, and the three arcs 71, 72, 73 are tangent arcs having different curvature radii. The blade 21 in FIG. 11B connects the three arcs 81, 82, 83 by connecting portions 84, 85. These connection portions 84 and 85 are short straight lines or curves connecting the arcs.

  FIG. 12 shows still another embodiment of the present invention.

  The wing 21 shown in FIG. 12 is another example of the shape of the wing. After the wing 21 has a thickness, the leading edge 31 and the trailing edge 32 of the wing 21 are subjected to appropriate R processing (curved surface processing). And has been cut. Further, the pressure surface side 11 and the suction surface side 12 may or may not be the same curve. The suction surface side 12 may often be provided with a protrusion shape or the like. Furthermore, the outer peripheral side of the blade has the cross-sectional shape described in the above embodiments, and the inner peripheral side of the blade has a different cross-sectional shape. That is, the characteristic shape of the blade 21 as in each of the above-described embodiments does not need to be configured from the boss root to the outer periphery of the blade, and in FIG. 2, the outer peripheral portion of each blade 21 from the center CL of the hub 22. As the radius W up to 33, it is desirable that the radius W1 from the center CL of the hub 22 is at least in the range of 0.7 W to 0.9 W.

FIG. 13 shows the relationship of the flow rate (m ³ / h) to the static pressure (Pa) for the embodiment of the present invention and the comparative example.

  In FIG. 13, the embodiment of the present invention is indicated by a solid broken line L1, and the comparative example is indicated by a broken broken line L2. When the broken line L1 and the broken line L2 are compared, the flow rate (air volume) of the embodiment of the present invention is increased as shown by the arrow B at the same static pressure (pressure loss) as compared with the comparative example. Fan performance is improved.

  FIGS. 14A and 14B show examples of the shape of the wing 21 using a trigonometric function, and are illustrated using a horizontal and vertical xy coordinate system for easy understanding as a function. .

  A blade 21 shown in FIG. 14A is formed using a trigonometric function. The neutral line 40 is a straight line, and this trigonometric function is as follows.

y = a.x.sin (b.x)
The wing 21 shown in FIG. 14B is formed by a composite function that is the sum of a function representing an arc and the trigonometric function so that the neutral line 40R draws an arc. As in the example shown in FIGS. 14A and 14B, the use of an existing trigonometric function facilitates the design of the axial fan.

  The axial fan according to the present invention is an axial fan in which a plurality of blades are integrally formed around a hub, and a cross-sectional shape along the rotation direction of the blades bulges toward the suction surface side of the blades. It has three or more bulging portions that alternately bulge to the pressure surface side of the blade, and bulges to the bulging portion and the pressure surface side that bulge to the suction surface side. The line that equally divides the bulging portion is the neutral line of the wing, and the bulging portion has a distance from the neutral line of the wing toward the trailing edge of the wing from the leading edge of the wing. Therefore, it is formed to be large. As a result, the axial fan can improve the air volume without making high rotation at a low blade height, and can increase fan efficiency with low noise.

  In the axial fan according to the present invention, when the number of the bulging portions is an odd number, the bulging portion on the front edge side is a bulging portion that bulges toward the negative pressure surface side, and the bulging portion When the number of parts is an even number, the bulging part on the front edge side is set as a bulging part that bulges to the pressure surface side. Thus, by determining the direction in which the first bulging portion of the front edge portion becomes convex, the terminal angle on the rear edge portion side of the axial fan can be increased, so that the air volume can be increased.

  The outdoor unit of the air conditioner of the present invention blows air to the compressor, the outdoor heat exchanger, and the outdoor heat exchanger in the outdoor unit main body. As a result, the axial fan can improve the air volume without making high rotation at a low blade height, and can increase fan efficiency with low noise.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.
The cross-sectional shape of the blade need not be configured up to the boss root of the axial flow fan. The base of the boss must have a shape that emphasizes maintaining the strength of the entire wing, and the wing length is short, and the peripheral speed decreases as the radius decreases even if the angular speed is constant. Because.

  Therefore, in the embodiment of the present invention, a three-dimensional wing shape that changes discontinuously or gradually toward the base of the boss is obtained.

  Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

It is a horizontal sectional view which shows preferable embodiment of the outdoor unit of an air conditioner provided with the axial flow fan of this invention. It is the front view which looked at the axial flow fan shown in FIG. 1 from the S direction. It is sectional drawing of the wing | blade in the AA line along the cylindrical cut surface 35 of each wing | blade 21 shown in FIG. It is sectional drawing which shows the shape and rotation direction R of the blade | wing 21 shown in FIG. 3 of embodiment of this invention. FIG. 5 (A) shows the cross-sectional shape of the blade of the embodiment of the present invention shown in FIG. 4, and FIG. 5 (B) shows a comparative example of a single blade with the same rush angle and terminal angle. It is a figure which shows a cross-sectional shape. 6A shows a cross-sectional shape of the blade of the embodiment of the present invention shown in FIG. 4, and FIG. 6B shows a comparative example in which the amplitude of the bulging portion is rearward from the front edge portion of the blade. It is a figure which shows the cross-sectional shape in the same case to an edge part. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows the relationship of the flow volume (m < ³ > / h) with respect to a static pressure (Pa). It is a figure which shows the example of a shape of the wing | blade 21 using a trigonometric function.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Heat exchanger, 11 ... Outdoor unit of air conditioner, 12 ... Outdoor unit main body, 3 ..., 14 ... Compressor, 15 ... Motor, 20 ... Axial fan, 21 ... Blade, 22 ... Hub, 31 ... Previous Edge part, 32 ... rear edge part, 35 ... cylindrical cut surface, 40 ... neutral line, 41, 42 ... undulation vertex line, 51, 52, 53 ... bulge part, 61 ... pressure surface side, 62 ... suction surface side, θ1 ... rush angle, θ2 ... end angle

Claims (3)

In the axial fan that integrally forms a plurality of blades around the hub,
A cross-sectional shape along the rotation direction of the blade when the blade is cut by a cylindrical surface centered on the center of the hub has a bulging portion that bulges to the suction surface side of the blade, and a pressure surface side of the blade Bulges that bulge into three or more alternating locations,
A line that equally divides the bulging portion that bulges to the suction surface side and the bulging portion that bulges to the pressure surface side is a neutral line of the wing,
The swollen portion is formed such that a distance from the neutral line of the wing increases from the leading edge of the wing toward the trailing edge of the wing. fan. When the number of the bulging parts is an odd number, the bulging part on the front edge side is a bulging part that bulges to the suction surface side, and when the number of the bulging parts is an even number, 2. The axial fan according to claim 1, wherein the bulging portion on the front edge side is a bulging portion that bulges toward the pressure surface. An air conditioner comprising: a compressor, an outdoor heat exchanger, and the axial fan according to claim 1 for blowing air to the outdoor heat exchanger in an outdoor unit main body. The outdoor unit of the machine.

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