JP5425192B2 - Propeller fan - Google Patents

Description

  The present invention relates to a propeller fan used for a ventilation fan, an air conditioner, or the like.

  Conventionally, in a propeller fan in which a plurality of blades are provided on the outer peripheral portion of a boss attached to a rotating shaft, the position where the amount of warpage becomes the maximum in the cylindrical cross section of the blade cut from the rotating shaft along an arbitrary radius is A propeller fan positioned on the trailing edge side of a blade as the radius increases is disclosed (see, for example, Patent Document 1).

  Further, in the axial fan including a hub that rotates by receiving a driving force and blades connected to the periphery of the hub, the blades are thin-walled blades and have warpage. In addition, an axial fan is disclosed that is provided within a range of 5 to 8% of the chord length and has a maximum camber position within a range of 20 to 40% of the chord length (for example, Patent Document 2). reference).

Japanese Patent No. 3608038 JP-A-2-233899

  However, according to the conventional technique, a large blade outer edge vortex is generated at the blade outer edge. Therefore, there has been a problem that the air blowing-noise characteristics are deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a propeller fan that suppresses a blade outer edge vortex generated at a blade outer edge of the propeller fan and has improved air blowing-noise characteristics.

In order to solve the above-described problems and achieve the object, the present invention provides a propeller fan including a hub fitted to a rotating shaft and a plurality of blades provided radially on the hub for blowing air in the rotating shaft direction. In the first region of the blade from the rotation axis to a predetermined radius, the ridge line of the largest camber in the cylindrical section of the blade cut along the arbitrary radius from the rotation axis is the chord length from the blade leading edge. of it is in the 35% position, wherein in the second region of the wing from the given radius to blade edge, ridge of maximum camber in the cylindrical section of the blade taken along any radius from the axis of rotation, said in a predetermined radial position connected to the ridge line of maximum camber of the first region, in proportion to the radius increases located blade trailing edge side, the 50% position of the chord length from the leading edge at the wing edge It is characterized by that.

  The propeller fan according to the present invention has an effect of suppressing the blade outer edge vortex generated at the blade outer edge and improving the blowing-noise characteristics.

FIG. 1 is a perspective view showing a general propeller fan. FIG. 2-1 is a plan view of the propeller fan according to the first embodiment of the present invention. FIG. 2-2 is a cylindrical cross-sectional view of the first region of the wing of the first embodiment. FIG. 3A is a perspective view schematically showing an air flow on the suction surface side of the blade of the first embodiment. 3-2 is a cross-sectional view taken along line FF in FIG. 3-1. FIG. 4A is a diagram illustrating an airflow around a wing of the wing having the conventional camber CLD of FIG. 2-2. FIG. 4B is a diagram illustrating an airflow around the blade of the blade having the camber CLD ′ according to the first embodiment illustrated in FIG. FIG. 5 shows a comparison between the specific noise characteristic of the blade having the ridge line CL ′ of the maximum camber of the first embodiment shown in FIG. 2 and the specific noise characteristic of the blade having the ridge line CL of the conventional maximum camber. FIG. FIG. 6 is a perspective view showing a propeller fan having a blade according to the second embodiment in which the blade inner peripheral front edge side of the blade having the maximum camber ridge line CL ′ of the first embodiment is formed in a waveform. FIG. 7 is a perspective view schematically showing an airflow on the suction surface side of the blade of the second embodiment shown in FIG. FIG. 8 is a perspective view showing a propeller fan having the blade of the third embodiment in which the blade inner peripheral trailing edge side of the blade having the maximum camber ridge line CL ′ of the first embodiment is formed in a waveform. FIG. 9 is a perspective view schematically showing an air flow on the suction surface side of the blade of the third embodiment shown in FIG. FIG. 10 is a diagram showing the specific noise of the blades shown in FIGS. 6 and 8. FIG. 11 is a perspective view showing a propeller fan having a blade whose outer peripheral side is bent toward the upstream side of the airflow. 12 is a perspective view schematically showing an air flow on the suction surface side of the blade shown in FIG. FIG. 13 is a plan view of the propeller fan shown in FIG. 1 projected onto a plane orthogonal to the rotation axis. FIG. 14 is a diagram in which the trajectory of each chord center point Pr in FIG. 13 is rotationally projected with a radius R onto a vertical plane including the rotation axis and the 0X axis. FIG. 15 is a diagram showing a chord centerline Pr1 of a blade whose outer peripheral side is bent toward the upstream side of the airflow. FIG. 16 is a view similar to FIG. 15 showing a method of defining the chord centerline Pr1 of the blade whose outer peripheral side is bent toward the upstream side of the airflow. FIG. 17 is a wing having the camber ridge line CL ′ of the first embodiment shown in FIG. 2A, schematically showing the airflow on the suction surface side of the wing with the blade outer peripheral side bent toward the upstream side of the airflow. FIG. FIG. 18 is a diagram illustrating specific noise of the propeller fan according to the fourth embodiment of the present invention. FIG. 19 is a diagram illustrating the fan efficiency of the propeller fan according to the fourth embodiment.

  Embodiments of a propeller fan according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
1 is a perspective view showing a general propeller fan, FIG. 2-1 is a plan view of the propeller fan according to the first embodiment of the present invention, and FIG. 2-2 is a blade according to the first embodiment. It is a cylindrical sectional view of the 1st field.

  The propeller fan shown in FIG. 1 has three blades. However, in the present invention, the number of blades is not limited and may be other plural numbers. In the following description, the shape of one wing is mainly described, but the shapes of the other wings are the same.

  A wing 1 having a three-dimensional solid shape shown in FIG. 1 is radially attached to the outer peripheral portion of a cylindrical hub 2 that is driven to rotate by a motor (not shown) and rotates about a rotation axis 3 in the direction of rotation B. Yes. Although the hub 2 is cylindrical, the wings 1 may be formed radially on the outer periphery of a boss formed by bending a sheet metal. The rotation of the blade 1 generates an airflow in the airflow direction A. The upstream surface of the blade 1 is a negative pressure surface, and the downstream surface is a positive pressure surface.

  When the blade 1 shown in FIG. 1 is projected onto a plane orthogonal to the rotation axis 3, a shape like the blade 1 shown in FIG. A broken line CL shown in FIG. 2A is a ridge line of the conventional maximum camber of the blade 1 (the locus of the top of the camber), and is located at the center of the blade leading edge 1b and the blade trailing edge 1c. The camber of the blade 1 has an arc shape like a broken line CLD (conventional camber) shown in FIG.

  In the blade 1 of the first embodiment, the ridge line CL ′ of the maximum camber is positioned at the rim line of the maximum camber at CL1 ′ on the inner periphery side from the radius R2 with the predetermined radius R2 as the boundary, and the maximum camber ridgeline CL2 on the outer periphery side from the radius R2. The ridge line of the camber is positioned at CL2 ′. That is, on the inner peripheral side from the radius R2, the ridge line CL1 ′ of the maximum camber is closer to the blade leading edge 1b than the ridge line CL of the conventional maximum camber located at the center of the blade leading edge 1b and the blade trailing edge 1c of the blade 1. It has a non-arc shape like the solid line CLD ′ (the camber of the first embodiment) shown in FIG.

  FIG. 3A is a perspective view schematically showing an air flow on the suction surface side of the blade according to the first embodiment, and FIG. 3B is a cross-sectional view taken along line FF in FIG. When the blade 1 rotates in the direction of rotation B, air flows in the direction A of the airflow. A pressure difference is generated between the suction surface 1f and the pressure surface 1g of the blade 1, and, as shown in FIG. 3-2, the leakage flow from the pressure surface 1g side to the suction surface 1f side and the blade outer edge at the blade outer edge 1d. A vortex G is generated. On the other hand, a blade inner peripheral flow E substantially along the suction surface 1f is generated on the blade inner peripheral side. As described above, the airflow on the suction surface 1f side of the propeller fan 91 according to the first embodiment is roughly divided into two airflows having different forms of the blade outer peripheral flow D and the blade inner peripheral flow E.

  FIG. 4A is a diagram illustrating the airflow around the blade of the wing having the conventional camber CLD of FIG. 2B. FIG. 4B includes the camber CLD ′ of the first embodiment of FIG. It is a figure which shows the airflow around the wing | blade of a wing | blade.

  As shown in FIG. 4A, when the blade 1 rotates in the rotation direction B, a flow from the blade leading edge 1b toward the blade trailing edge 1c is generated. The suction surface airflow H in the conventional camber CLD having the ridgeline CL of the maximum camber becomes unstable and vortex is generated as it approaches the blade trailing edge 1c. A trailing edge vortex J is generated. Such vortices in the suction surface airflow H and blade trailing edge vortices J generate noise.

  On the other hand, as shown in FIG. 4B, the negative pressure surface airflow H ′ in the camber CLD ′ of the first embodiment having the maximum camber ridge line CL ′ is such that the air flowing from the blade leading edge 1 b is more than the conventional camber CLD. Also flows along the suction surface 1f, the generation of vortices is suppressed, the size of the blade trailing edge vortex J 'generated at the blade trailing edge 1c is reduced, and the noise is reduced as compared with a blade having a conventional camber CLD. .

  As described above, the wing 1 is shaped like the camber CLD ′, so that the disturbance of the suction surface air flow H ′ is reduced and the noise is reduced. However, as shown in FIG. In the fan 91, since a large blade outer edge vortex G is generated in the blade outer peripheral flow D, the flow state is significantly different from the blade inner peripheral flow E. For this reason, if the camber on the outer periphery of the blade is uniformly the camber CLD ′, the blade outer edge vortex G may change greatly, and the blower-noise characteristics may deteriorate.

  Therefore, in the propeller fan 91 of the first embodiment, as shown in FIG. 2A, the ridge line CL ′ of the maximum camber of the blade 1 is set to a ridge line having different forms of CL1 ′ and CL2 ′, and the ridge line CL1 ′ of the maximum camber is used. The blade is positioned within 50% of the blade chord length from the blade leading edge 1b, and the blade trailing edge 1c side as the radius increases from the position where the ridge line CL2 'of the largest camber outer peripheral portion is connected to the ridge line CL1' of the largest camber And located within 50% of the chord length at the blade outer edge 1d. Reference sign CLt shown in FIG. 2A is the maximum camber position at the blade outer edge, reference sign CLb is the maximum camber position at the blade inner edge of the conventional blade, and reference sign CLb ′ is the blade inner edge of the blade of the first embodiment. Is the maximum camber position.

  FIG. 5 shows a comparison between the specific noise characteristic of the blade having the ridge line CL ′ of the maximum camber of the first embodiment shown in FIG. 2 and the specific noise characteristic of the blade having the ridge line CL of the conventional maximum camber. FIG. In the first region from the blade inner edge 1e to the blade radius R2 = 0.675 × Rt (Rt is the blade outer edge radius), the ridge line CL ′ of the maximum camber of the first embodiment shown in FIG. 5 is from the blade leading edge 1b. In the second region from R2 = 0.675 × Rt to the blade outer edge 1d in the second region from the blade leading edge 1b to the blade chord length, the radius increases from 35% of the blade chord length. It is located on the trailing edge 1c side, and is located at a position of 50% of the chord length on the blade outer edge 1d. The conventional blade used for comparison is a blade in which the ridge line CL of the maximum camber is located at a position of 50% of the chord length from the blade leading edge 1b.

The specific noise _KT is defined by the following equation.
_{K T = SPL A -10Log (Q} · P T 2.5)
Q: Air volume [m ³ / min]
P _T : Total pressure [Pa]
SPL _A : Noise characteristics (after A correction) [dB]

  In FIG. 5, the vertical axis represents specific noise, one scale indicated by a broken line represents a difference of 1 [dBA], and the horizontal axis represents the air volume. As shown in FIG. 5, the blade having the maximum camber ridge line CL ′ of the first embodiment has a noise level of about −1 [dBA] at maximum.

Embodiment 2. FIG.
FIG. 6 is a perspective view showing a propeller fan 92 having the blade 21 of the second embodiment in which the blade inner peripheral front edge side of the blade having the maximum camber ridge line CL ′ of the first embodiment is formed in a waveform 21 m. The waveform of the blade leading edge 21b is set to the maximum waveform, and gradually decreases toward the blade center.

  FIG. 7 is a perspective view schematically showing the airflow on the suction surface side of the blade 21 of the second embodiment shown in FIG. As shown in FIG. 7, a vertical vortex is generated in the air flowing into the blade leading edge 21b by the waveform 21m of the blade 21, and the blade inner circumferential flow E is changed to an air flow E2 with less turbulence, resulting from the turbulence of the air flow. Noise can be reduced.

Embodiment 3 FIG.
FIG. 8 is a perspective view showing a propeller fan 93 having the blade 31 of the third embodiment in which the trailing edge side of the inner peripheral portion of the blade having the ridge line CL ′ of the maximum camber of the first embodiment is formed in a waveform 31n. The waveform of the blade trailing edge 31c is set to the maximum waveform, and gradually decreases toward the center of the blade.

  FIG. 9 is a perspective view schematically showing the airflow on the suction surface side of the blade 31 of the third embodiment shown in FIG. As shown in FIG. 9, the turbulence of the air due to the vortex generated at the blade trailing edge 31c is reduced by the vertical vortex generated by the waveform 31n of the wing 31 to obtain a less turbulent air flow E3, resulting in the turbulence of the air flow. Noise can be reduced.

  FIG. 10 is a diagram illustrating the specific noise of the blades 21 and 31 illustrated in FIGS. 6 and 8. As shown in FIG. 10, in the region where the air volume is large, the blades 21 and 31 having a waveform on the inner peripheral side of the blade have a lower noise level by about −0.5 [dBA] at the maximum.

Embodiment 4 FIG.
11 is a perspective view showing a propeller fan having a blade whose outer peripheral side is bent toward the upstream side of the airflow, and FIG. 12 is a perspective view schematically showing an airflow on the suction surface side of the blade shown in FIG. . The propeller fan having a blade whose outer peripheral side is bent toward the upstream side of the air flow shown in FIGS. 11 and 12 can weaken the blade outer edge vortex generated on the blade outer edge negative pressure surface and reduce noise caused by the blade outer edge vortex. However, since the outer peripheral side of the blade is bent toward the upstream side of the airflow, the pressure increase component generated by the rotation of the blade partially leaks to the negative pressure surface side, and the fan efficiency is slightly reduced.

  The blade noise sources as shown in FIGS. 1 and 11 are caused by the blade outer edge vortex generated at the blade outer edge, the blade suction surface flow turbulence, and the blade trailing edge vortex. There is something. In a blade whose outer peripheral side is bent toward the upstream side of the airflow, the proportion of noise caused by the blade outer edge vortex is reduced, and the proportion of noise generated from the inner peripheral flow is relatively increased. Therefore, it is necessary to improve the inner peripheral flow of the blade and to examine the shape of the blade that does not affect the outer peripheral flow of the blade.

  Even in a blade whose outer peripheral side is bent to the upstream side of the airflow, by forming a ridge line CL ′ of the maximum camber as shown in FIG. 2A, noise caused by the outer edge vortex without affecting the peripheral flow of the blade. Can be reduced, the flow inside the blade can be improved, noise can be further reduced, and fan efficiency can be improved.

  13 is a plan view in which the propeller fan shown in FIG. 1 is projected onto a plane orthogonal to the rotation axis, and FIG. 14 shows the trajectory of each chord center point Pr in FIG. 13 including the rotation axis and the 0X axis. FIG. 15 is a diagram showing the blade chord centerline Pr1 of the blade whose outer peripheral side is bent toward the upstream side of the airflow, and FIG. 16 is a diagram showing the blade outer peripheral side upstream of the airflow. FIG. 16 is a view similar to FIG. 15 showing a method of defining a chord centerline Pr1 of a wing bent sideways.

  With reference to FIGS. 13 to 16, the definition of the shape of a blade whose outer peripheral side is bent toward the upstream side of the airflow will be described. When the blade 1 shown in FIG. 1 is projected onto a plane Sc (see FIG. 14) orthogonal to the rotation axis 3, the shape of the blade 1 shown in FIG. 13 is obtained. A point Pb shown in FIG. 13 indicates a chord center point (middle point) from the blade leading edge 1 b to the blade trailing edge 1 c on the outer periphery of the hub 2.

  Similarly, Pt indicates the chord center point (midpoint) from the blade leading edge 1b to the blade trailing edge 1c at the blade outer edge 1d. A line Pr shown in FIG. 13 indicates a locus (chord chord centerline) of each chord center point at an arbitrary radius R from the chord center point Pb of the hub to the chord center point Pt of the outer edge of the blade.

  FIG. 14 shows the trajectory (blade chord center line) of each chord center point from the chord center point Pb of the hub to the chord center point Pt of the outer edge of FIG. 13, that is, the chord center point Pb-Pr-Pt. FIG. 5 is a diagram showing a locus (chord chord centerline) of each chord center point Pr obtained by rotating and projecting each chord center point Pr at an arbitrary radius R on the vertical plane including the rotation axis 3 and the 0X axis at the radius R. is there.

  As shown in FIG. 14, the chord centerline Pr (the trajectory of each chord center point Pr) that is rotationally projected onto a vertical plane including the rotation axis 3 and the 0X axis is the blade chord center point Pb of the hub 2. The forward tilt angle δz that is inclined to the upstream side of the airflow up to the chord center point Pt of the outer edge can be represented as a line that forms a certain angle with the plane Sc that is orthogonal to the rotation axis 3.

  The chord centerline Pr indicated by a broken line in FIG. 15 is a locus of the chord center point of the wing 1 having a forward tilt angle δz shown in FIG. 14, and the wing outer periphery is bent toward the upstream side of the airflow. The chord center line Pr1 representing the trajectory of the chord center point is the chord center line Pr when the forward tilt angle is constant in the region from the chord center point Pb of the hub to the chord center point Pt of the outer edge of the hub. It is located in a region sandwiched between the 0X axis (forward tilt angle = 0 °) passing through the chord center point Pb and orthogonal to the rotation axis 3.

  The chord centerline Pr and the chord centerline Pr1 are such that the chord center point Pb of the hub and the chord center point Pt of the blade outer edge are at the same position, and the chord center point Pt of the blade outer edge from the plane Sc of the chord center point Pt. The distance is H.

  FIG. 16 shows the trajectory and forward tilt angle of each chord center point Pr2 of the blade of the fourth embodiment in which the blade outer periphery is bent toward the upstream side of the airflow A. A chord center point at an arbitrary radius R from the rotation axis 3 is Pr2, and a distance from the plane Sc perpendicular to the rotation axis 3 of the chord center point Pr2 located on the chord centerline Pr1 is Ls.

  In the wing 41 of the fourth embodiment shown in FIG. 16, the first region from the hub 2 (radius Rb) to the bending point Pw in the radial intermediate portion is inclined to the upstream side at a constant first forward inclination angle δzw. The second region from the point Pw to the blade outer edge is inclined further upstream than the first region.

The radius of the bending point Pw on the chord center line Pr1 is Rw, and the second inclination angle is the upstream angle of the line Pr connecting the chord center point Pt on the outer edge of the blade and the chord center point Pb on the outer periphery of the hub 2. Let the forward tilt angle be δzt. The first forward tilt angle δzw is expressed by the following equation.
δzw = tan ⁻¹ (Ls / (R−Rb))
(Rb <R ≦ Rw)

The inclination angle δzd corresponding to the chord center point Pr2 at an arbitrary radius R in the second region between the bending point Pw and the blade outer edge (radius Rt) is an n-order function of the radius R ( 1 ≦ n).
δzd = α (R−Rb) ⁿ + δzw
α = (δzt−δzw) / (Rt−Rw) ⁿ
(Rw <R ≦ Rt)
It should be noted that the chord center line Pr1 in the second region is linearly inclined upstream at a certain forward tilt angle without using the tilt angle δzd as an n-order function (1 ≦ n) of the radius R. Also good.

  FIG. 17 is a wing having the ridge line CL ′ of the maximum camber of the first embodiment shown in FIG. 2A, and the airflow on the blade suction surface side of the wing 41 whose outer peripheral portion is bent toward the upstream side of the airflow. FIG. As shown in FIG. 17, according to the blade 41 of the fourth embodiment, the blade outer peripheral flow and the blade inner peripheral flow can be improved at the same time, and the blower-noise characteristics can be improved.

  FIG. 18 is a diagram illustrating specific noise of the propeller fan according to the fourth embodiment of the present invention, and FIG. 19 is a diagram illustrating fan efficiency of the propeller fan according to the fourth embodiment. In the first region of R = 0.675 × Rt from the blade inner edge, the maximum camber ridgeline CL ′ is located 35% of the chord length from the blade leading edge in the propeller fan blade 41 of the fourth embodiment. In the second region from R = 0.675 × Rt to the blade outer edge, the ridge line CL ′ of the maximum camber is arranged from the position of 35% of the chord length to the position of 50% of the chord length at the blade outer edge. .

In the blade having the ridge line CL of the conventional maximum camber used for comparison, the ridge line CL of the maximum camber is located at a position of 50% of the chord length from the blade leading edge, and the bending point radius is Rw = 0.7 × Rt, an inclination angle δzd corresponding to the chord center point Pr2 at an arbitrary radius R in the second region from the bending point Pw to the blade outer edge (radius Rt) is determined by a quadratic function of the radius R, and The inclination angle of the tangent line 15 of the chord line center line Pr1 at the chord line center point Pt of the wing outer edge is δzs = 45 ° (see FIG. 16). Figure 18 shows the result of obtaining a relation between air volume Q and the specific noise K _T experimentally, Figure 19 shows the results obtained experimentally the relationship between the air volume Q and the fan efficiency E _T.

As shown in FIGS. 17 and 18, the propeller fan 94 according to the fourth embodiment has a specific noise _KT reduced in a practical range as compared with a conventional propeller fan whose blade outer peripheral portion is bent toward the upstream side of the airflow. (-1DBA) is, and the fan efficiency _{E T} is improved (about up to + 2-3 points).

Incidentally, the fan efficiency E _T is defined by the following equation.
E _T = (P _T · Q) / (60 · P _W )
Q: Air volume [m ³ / min]
P _T : Total pressure [Pa]
P _W : Shaft power [W]

  As described above, the propeller fan according to the present invention is suitable for a ventilation fan, an air conditioner, and the like.

1, 21, 31, 41 Blade 1b, 21b Blade leading edge 1c, 31c Blade trailing edge 1d Blade outer edge 1e Blade inner edge 1f Negative pressure surface 1g Pressure surface 21m, 31n Waveform 2 Hub 3 Rotating shaft A Airflow direction B Rotation direction R1 Blade Arbitrary radius in the first region R2 Boundary radius between the blade first region and the blade second region CL Edge of the maximum camber of the conventional blade CL 'Edge of the maximum camber of the blade according to the first embodiment CLD Conventional camber of the blade CLD' Blade camber CL1 ′ of the first embodiment Maximum camber ridgeline CL2 ′ of the first blade region of the first embodiment CL2 ′ Maximum camber ridgeline of the second blade region of the first embodiment CLt Maximum camber position at the blade outer edge CLb Conventional Maximum camber position at the blade inner edge of the blade CLb 'Maximum camber position at the blade inner edge of the blade according to Embodiment 1 D Blade outer flow E Blade inner flow E2, E3 Airflow G Outer edge vortex H Conventional blade suction surface flow H ′ Embodiment 1 suction surface flow J Conventional blade wing trailing edge vortex J ′ Embodiment 1 blade trailing edge vortex 91, 92, 93, 94 Propeller Fan

Claims (3)

In a propeller fan comprising: a hub that is fitted to a rotation shaft; and a plurality of blades that are provided radially on the hub and blows air in the direction of the rotation shaft.
In the first region of the wing from the rotation axis to a predetermined radius, the ridge line of the largest camber in the cylindrical cross section of the wing cut along the arbitrary radius from the rotation axis is a chord length of 35 from the blade leading edge. % Position ,
In the second region of the blade from the predetermined radius to the blade outer edge, the ridge line of the largest camber in the cylindrical cross section of the blade cut along the arbitrary radius from the rotation axis is the first camber at the predetermined radius position. Propeller connected to the ridge line of the largest camber in the region, located on the trailing edge side of the blade in proportion to the increase in radius, and located at 50% of the chord length from the leading edge of the blade at the outer edge of the blade fan.   The propeller fan according to claim 1, wherein the blade inner circumferential leading edge side or the blade inner circumferential trailing edge side is formed in a corrugated shape.   The propeller fan according to claim 1, wherein the blade outer peripheral side is bent toward the upstream side of the airflow.

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