JP4818184B2 - Propeller fan - Google Patents

Description

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

  As a conventional propeller fan, a propeller fan comprising a hub and a plurality of blades radially formed on the outer peripheral side of the hub, wherein the plurality of blades have a blade outer peripheral portion from a blade leading edge side to a blade trailing edge side. And a bent portion formed so that the height of the outer peripheral edge of the blade with respect to the blade surface is maximized on the blade leading edge side rather than the middle of the chord length. Some reduce the wing tip vortex and reduce the blowing noise caused by the wing tip vortex (see, for example, Patent Document 1).

Japanese Patent No. 3801162

  In the conventional general propeller fan, the blade tip vortex generated in the vicinity of the outer periphery of the blade interferes with the bell mouth of the casing, or peels off from the blade and interferes with the adjacent blade. There is a problem.

  Moreover, according to the technique described in Patent Document 1, in order to reduce the blowing sound caused by the blade tip vortex, the blade outer peripheral portion is bent from the leading edge side to the trailing edge side, so that the suction surface side is bent. In the region where the wing overlaps the bell mouth of the casing, there is a problem that air leakage from the pressure surface side to the suction surface side of the wing increases.

  Furthermore, in a blower equipped with a propeller fan or an outdoor unit of an air conditioner, the area where the propeller fan actually operates is an area where static pressure is applied to some extent, and there is a problem that the fan efficiency decreases near this area. is there.

  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 reduces noise and suppresses a decrease in fan efficiency in an area where the propeller fan actually operates.

  In order to solve the above-described problems and achieve the object, the present invention includes a hub that is rotationally driven by a motor, and a plurality of blades that extend radially outward from the hub and blow air in the rotational axis direction. In the propeller fan, the blade leading edge portion is inclined upstream at a constant first forward inclination angle greater than 0 ° in a first region from the hub to the bending point of the radial intermediate portion, and the blade outer peripheral portion is bent from the bending point to the blade outer peripheral portion. In the second region up to the first forward tilt angle, the forward tilt angle of the blade trailing edge is a constant second forward tilt angle of a line connecting the hub of the blade leading edge and the blade outer peripheral portion. And approximately matched.

  According to the present invention, there is an effect that in a region where the propeller fan actually operates, it is possible to obtain a propeller fan in which noise caused by the blade tip vortex is reduced and a decrease in fan efficiency is suppressed.

  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 FIG. 1 is a perspective view showing a propeller fan, FIG. 2 is a plan view of a projection of the propeller fan on a plane orthogonal to the rotation axis, and FIG. 3 is a chord center point in FIG. FIG. 4 is a perspective view of a wing having a constant forward tilt angle δz as shown in FIG. 3, in which the locus of Pr ′ is rotationally projected with a radius R onto a vertical plane including the rotation axis and the 0X axis. FIG. 5 is a cross-sectional view of a wing and a bell mouth having a constant forward tilt angle δz, and FIG. 6 is a diagram showing a chord centerline Pr1 of the wing whose outer peripheral portion is bent to the suction surface side. 7 is a view similar to FIG. 6 showing a method of defining a chord centerline Pr1 of a blade whose outer peripheral portion is bent toward the suction surface side, and FIG. 8 shows a chord centerline Pr1 as shown in FIG. FIG. 9 is a cross-sectional view of a wing and a bell mouth having a chord centerline Pr1, and FIG. FIG. 11 is a diagram illustrating a chord centerline of a propeller fan according to an embodiment of the invention, FIG. 11 is a diagram illustrating a position of a blade element at an arbitrary radius of a blade of the propeller fan according to the embodiment, and FIG. 4 and FIG. 5 having the chord centerline Pr shown in FIG. 3 and the deployment line 6 of the blade element at an arbitrary radius R ′ of the wing shown in FIGS. 4 and 5 and FIGS. 8 and 9 having the chord centerline Pr1 shown in FIG. FIG. 13 is a diagram illustrating a blade element development line 6 and a blade element development line 8 derived from the blade element development line 7. 14 is a perspective view of the propeller fan of the embodiment having the blade element deployment line 8, and FIG. 15 is a cross-sectional view of the propeller fan and the bell mouth of the embodiment having the blade element deployment line 8. FIG. 16 shows the cross-sectional position from the leading edge 1b ′ to the trailing edge 1c ′ of the wing of the embodiment. FIG. 17 is a view showing the positional relationship among the blade cross sections, blade tip vortices, and bellmouths A1 to A4 shown in FIG. 16, and FIG. 18 is a diagram showing the operating point and fan of the propeller fan according to the embodiment. FIG. 19 is a diagram in which the relationship between the operating point and the specific noise of the propeller fan according to the embodiment is experimentally determined.

  As shown in FIG. 1, the propeller fan usually has three blades. However, in the present invention, the number of blades is not limited, and may be a plurality of other blades. 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 an outer peripheral portion of a cylindrical hub 2 that is driven to rotate by a motor (not shown) and rotates around a rotation shaft 3 in the direction of an arrow 4. . Although the hub 2 of the embodiment is cylindrical, the wings 1 may be formed radially on the outer periphery of a boss formed by bending a sheet metal. An airflow in the direction of arrow A is generated by the rotation of the blade 1. 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 Sc (see FIG. 3) orthogonal to the rotation axis 3, the shape of the blade 1 ′ shown in FIG. 2 is obtained. A point Pb ′ shown in FIG. 2 indicates a chord center point (middle point) from the blade leading edge portion 1 b ′ to the blade trailing edge portion 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 ′ in the blade outer peripheral portion 1d. A line Pr ′ shown in FIG. 2 indicates a trajectory (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 periphery of the blade. .

  3 shows the trajectory (blade chord centerline) of each chord center point from the chord center point Pb ′ of the hub in FIG. 2 to the chord center point Pt ′ of the outer periphery of the blade, that is, the chord center point Pb′−. For Pr′-Pt ′, each chord center point Pr ′ at an arbitrary radius R is rotationally projected at a radius R onto a vertical plane including the rotation axis 3 and the 0X axis (the chord of each chord center point Pr) It is a figure which shows a centerline.

  As shown in FIG. 3, the chord centerline Pr (the trajectory of each chord center point Pr) that is rotationally projected on 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 inclines to the upstream side of the airflow up to the chord center point Pt of the outer peripheral portion can be expressed as a line that forms a constant angle with the plane Sc that is orthogonal to the rotation axis 3.

  FIG. 4 shows a perspective view of a wing having a chord centerline Pr with a constant forward tilt angle δz shown in FIG. 3, and FIG. 5 shows a cross-sectional view of the wing and the bell mouth 5.

  A chord centerline Pr indicated by a broken line in FIG. 6 is a locus of a chord center point of the wing 1 having a constant forward inclination δz shown in FIG. 3, and a chord centerline Pr1 indicated by a solid line in FIG. The outer peripheral portion is a trajectory of the chord center point of the wing warped (bent) in the upstream direction of the airflow A.

  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 outer periphery of the blade are at the same position, and the plane Sc of the chord center point Pt of the outer periphery of the blade The distance from is H.

  FIG. 7 shows the trajectory and forward tilt angle of each chord center point Pr2 of the blade whose outer periphery is warped in the upstream direction 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 blade shown in FIG. 7, the first region from the hub 2 (radius Rb) to the bending point Pw in the radial intermediate portion is inclined upstream at a constant first forward inclination angle δzw, and the blade outer peripheral portion from the bending point Pw. The second region up to is inclined further upstream than the first region.

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

The forward tilt 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 periphery (radius Rt) is an n-order function of the radius R as shown below. Further, the inclination angle δzs of the tangent line 15 of the chord center line Pr1 at the chord center point Pt of the outer peripheral portion is set within a range of 30 ° to 45 °.
δzd = α (R− Rw ) 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.

  8 is a perspective view of the blade shown in FIG. 7 having a chord centerline Pr1 bent from the blade leading edge portion 1b ′ to the blade trailing edge portion 1c ′ of the blade outer peripheral portion toward the suction surface side. FIG. 10 is a cross-sectional view of the wing and the bell mouth, and FIG. 10 is a diagram showing a method of defining the wing of the propeller fan according to the embodiment of the present invention.

  In order to obtain the blade shape of the embodiment, first, the blade shape shown in FIGS. 4 and 5 is obtained by determining the blade shape having the chord centerline Pr having a certain forward tilt angle shown by the broken line in FIG. Next, when the blade shape having the chord centerline Pr1 having the first forward tilt angle and the second forward tilt angle shown by the solid line in FIG. 10 is determined, the blade shape shown in FIGS. 8 and 9 is obtained.

  Here, as shown in FIG. 11, when the blade 1 is cut at an arbitrary radius R ′, a blade element 10 having an arbitrary radius is obtained. Consider a blade element in which the blade element 10 having an arbitrary radius R ′ is developed and projected on the ZY plane.

  First, a blade 1 having a chord centerline Pr, Pr1 as shown in FIGS. 3 and 6 is cut as shown in FIG. 11 and developed and projected onto the ZY plane. As shown in FIG. Elementary development lines 6 and 7 can be obtained.

Further, in the blade element development line 8 shown in FIG. 13, the rotation axis direction coordinate Za of the blade leading edge portion 1b ′ is made to coincide with the blade leading edge portion 1b ′ of the blade element development line 7, and the blade trailing edge portion 1c. The rotation axis direction coordinate Zb of ′ coincides with the blade trailing edge portion 1c ′ of the blade element development line 6 and at an arbitrary angular position θ therebetween, the rotation axis direction coordinate Za of the blade element development line 6 This is a development line of a blade element obtained by adding ΔZ represented by the formula.
ΔZ = α (θa−θb) − (Za−Zb)
Here, α = (Za−Zb) / (θa−θ).

  If the same operation is performed for an arbitrary radius R ′ from the outer peripheral portion 1 d ′ to the hub 2, the vicinity of the blade leading edge portion 1 b ′ in the upstream direction of the airflow A as shown in FIGS. A wing that warps so as to have one forward tilt angle and a second forward tilt angle and warps so that the vicinity of the blade trailing edge 1c ′ has a constant second forward tilt angle is obtained.

  FIG. 16 is a diagram in which the blade 1 and the hub 2 shown in FIGS. 14 and 15 are projected onto the axis perpendicular plane Sc. FIG. 17 shows a blade cross-sectional view of the blade 1 at positions A1 to A4 from the blade leading edge 1b ′ to the blade trailing edge 1c ′.

  FIG. 17 shows the relationship between the blade 1 and the blade tip vortex 9 when the blade 1 rotates. As shown in FIG. 17, at the position of the cross section A1 near the blade leading edge, the blade tip vortex 9 is generated as shown by the arrow in the figure due to the pressure difference between the negative and positive pressure surfaces of the blade. It grows from the leading edge 1b 'toward the blade trailing edge 1c'.

  By adopting the wing shape of the embodiment, as shown in FIG. 17, the wing tip vortex 9 moves to the inside of the wing outer peripheral portion 1d ′, and in the vicinity of the overlap portion of the wing 1 and the bell mouth 5, the wing tip vortex Air leakage can be prevented while preventing the interference between 9 and the bell mouth 5.

FIG. 18 shows the fan efficiency η _T of the propeller fan having the blade shape shown in FIG. 3 (FIGS. 4 and 5), FIG. 7 (FIGS. 8 and 9) and FIG. 10 (FIGS. 14 and 15). As shown in FIG. 18, the fan efficiency η _T of the blade of the embodiment shown in FIG. 10 is about +1.0 (points) over the entire area, compared with the fan efficiency η _{T of the} blade shown in FIG. Is expensive. For reference, the fan efficiency η _{T of the} blade shown in FIG. 3 is also shown.

19, 3 (FIGS. 4 and 5), shows a specific noise level K _T of the propeller fan having a blade shown in FIG. 7 (FIGS. 8, 9) and 10 (FIGS. 14 and 15). As shown in FIG. 19, the minimum ratio noise also small specific noise K _T of the wing of the embodiment shown in FIG. 10, approximately -1 dB, a low noise.

The operating point ξ _T , the specific noise K _T and the fan efficiency η _T are defined by the following equations.
ξ _T = P _T / Q ²
K _T = SPL _A -10 Log (Q · P _T ^2.5 )
η _T = (P _T · Q) / (60 · P _W )
Q: Air volume [m ³ / min]
P _T : Total pressure [Pa]
SPL _A : Noise characteristics (A correction) [dB (A)]
D: Propeller fan outer diameter [m]
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.

It is a perspective view which shows a propeller fan. It is the plane projection figure which projected the propeller fan on the plane orthogonal to the axis of rotation. FIG. 3 is a diagram in which the trajectory of each chord center point Pr ′ in FIG. 2 is rotationally projected with a radius R onto a vertical plane including a rotation axis and a 0X axis. FIG. 4 is a perspective view of a wing having a constant forward tilt angle δz as shown in FIG. 3. FIG. 4 is a cross-sectional view of a wing and a bell mouth having a constant forward tilt angle δz as shown in FIG. 3. It is a figure which shows the chord centerline Pr1 of the wing | blade which the outer peripheral part bent to the suction surface side. FIG. 7 is a view similar to FIG. 6 showing a method for defining a chord centerline Pr1 of a blade whose outer peripheral portion is bent toward the suction surface side. It is a perspective view of a wing | blade which has a chord centerline Pr1 as shown in FIG. FIG. 8 is a cross-sectional view of a wing having a chord centerline Pr1 as shown in FIG. 7 and a bell mouth. It is a figure which shows the chord centerline of the propeller fan of embodiment of this invention. It is a figure which shows the position of the blade element in the arbitrary radii of the blade | wing of the propeller fan of embodiment. 4 and FIG. 5 having a chord centerline Pr shown in FIG. 3 and a deployment line of a blade element at an arbitrary radius R ′ shown in FIGS. 4 and 5 and FIGS. 8 and 9 having a chord centerline Pr1 shown in FIG. It is a figure which shows the expansion | deployment line | wire of the blade element in arbitrary radius R 'of the blade shown. FIG. 5 is a diagram showing a blade element development line 8 derived from a blade element development line 6 and a blade element development line 7. It is a perspective view of the propeller fan of embodiment which has the deployment line 8 of the blade element shown in FIG. It is sectional drawing of the propeller fan and bellmouth of embodiment which have the deployment line 8 of the blade element shown in FIG. It is a figure which shows the cross-sectional position from the front edge part 1b 'of the wing | blade of embodiment to the rear edge part 1c'. It is a figure which shows the positional relationship of the blade cross section, blade tip vortex, and bellmouth of A1-A4 shown in FIG. It is the figure which calculated | required experimentally the relationship between the operating point (xi) _T of the propeller fan of embodiment, and fan efficiency (eta) _T. A graph of the obtained empirically the relationship between the operating point xi] _T and the specific noise level K _T of the propeller fan of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 wing | blade 1 'wing | blade projected on the surface orthogonal to a rotating shaft 1b' wing | blade front edge part 1c 'wing | blade trailing edge part 1d' wing | blade outer peripheral part 2 hub 3 rotating shaft 4 rotation direction A direction of airflow Pb, Pb 'blade of hub Chord center point Pt, Pt 'chord center point Pr of the blade outer periphery Pr, Pr' chord center line of the blade having a certain forward tilt angle Pr1 blade chord center line of the blade with the blade outer periphery bent to the suction side Pr2 blade The chord center point Pw of the blade whose outer peripheral portion is bent to the suction surface side Pw The bending point that becomes the starting point for changing a certain forward tilt angle Sc The plane that passes through the chord center point of the hub and is orthogonal to the rotation axis H The chord of the outer periphery of the blade Distance 15 from the center point Pt to the plane Sc 15 Tangent line of the chord center line at the chord center point Pt of the outer peripheral portion δz Blade forward tilt angle δzw Constant forward tilt angle (first forward tilt angle) of the first region inside the bending point Pw )
δzt Forward tilt angle of the line connecting the chord center point Pb of the hub and the chord center point Pt of the outer periphery of the blade (second forward tilt angle)
δzd The forward tilt angle of the line connecting the chord center point Pr2 and the chord center point Pb of the hub at an arbitrary radius R in the second region outside the bending point Pw δzs Pre-tilt angle of tangent to center line Pr1 R 'Arbitrary radial position 5 Bellmouth 6 Blade element expansion line at arbitrary radius R' of wing shown in Figs. 4 and 5 having chord centerline Pr 7 Chord centerline Pr1 8 and 9, the development line of the blade element at an arbitrary radius R ′ shown in FIGS. 8 and 9. 8 The blade leading edge coincides with the blade element 7, and the blade trailing edge coincides with the blade element 6. Z Rotational axis direction θ Arbitrary circumferential angle Y Axis perpendicular to X axis 10 Blade element of arbitrary radius Za Rotational axis coordinate of leading edge of blade element 6 θa Circumferential angular coordinate of leading edge of blade element 6 Zb Rotational axis coordinate of the trailing edge of the blade element 7 θb Circumferential angular coordinate of the trailing edge of the blade element 7 A1 Blade cross-sectional position 1
A2 Blade cross section position 2
A3 Blade cross section position 3
A4 Blade cross section position 4
9 Blade tip vortex A1 'Blade section at A1 Blade section at A2' A2 Blade section at A3 'A3 Blade section at A4' A4

Claims (3)

In a propeller fan comprising: a hub that is rotationally driven by a motor; and a plurality of blades that extend radially outward from the hub and blow air in the direction of the rotation axis.
The blade leading edge is inclined upstream at a constant first forward tilt angle greater than 0 ° in the first region from the hub to the bending point of the radially intermediate portion, and the second edge from the bending point to the blade outer peripheral portion. Incline further upstream than the first forward tilt angle in the region,
The forward tilt angle of the blade trailing edge is substantially matched with a constant second forward tilt angle of a line connecting the hub of the blade leading edge and the blade outer periphery,
The rotation axis direction coordinate of the blade element at any same radius from the hub to the blade outer periphery of the blade is the same as the rotation axis direction coordinate of the blade element at the blade leading edge of the same radius. propeller fan, characterized in that has a rotation axis coordinates of the blade element in the trailing edge portion of a coordinate between. Inclination before corresponding chord center point at any radius in the second region between the bending point to the blade outer peripheral part, according to claim 1, characterized in that has a radius of n-th order function Propeller fan. 2. The propeller fan according to claim 1 , wherein a chord centerline in a second region between the bending point and a blade outer peripheral portion is linearly inclined upstream at a certain forward inclination angle.

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