JPH11294389A - Mixed flow air blower impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a low noise of a mixed flow air blower impeller and to improve its static pressure. SOLUTION: In a mixed flow air blower impeller made by providing plural sheets of thin blades 2 to an about truncated conical hub 3, the front edge 6 of the blade 2 is made in a recess form to the windward at the outer peripheral side from about the middle point of the front edge 6 in the form of the rotary locus of the blade, and in a convex form of curved line to the windward at the hub 3 side from near the middle point, and further, the cross section form in the radial direction of the blade 2 is made in a recess form to the windward at the outer peripheral side from near the middle point of the blade 2, while made in a convex form of curved line to the windward at the hub 3 side from near the middle point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed flow blower impeller having a mixed flow blade used for a blower such as an air conditioner, and more particularly to a shape of the blade of the mixed flow fan.

[0002]

2. Description of the Related Art A conventional diagonal blower impeller having thin blades has a structure as shown in FIGS. That is, a plurality of thin blades 22
Are provided radially to constitute the mixed flow blower impeller 21.

The blade 22 has a cross section in the radial direction formed from the hub 23 side to the outer peripheral end side of the blade 22 in a substantially linear shape or a curved shape only in a single direction. Then, the mixed flow blower impeller 21 is housed in an appropriate casing and rotated to generate a blowing action.

[0004]

However, in the above-described conventional configuration, the blade 22 has a substantially linear cross-sectional shape in the radial direction or a shape that is curved only in a single direction. There is a limit in controlling the tip vortex generated near the outer periphery of the blade 22.

[0005] In addition, no improvement has been made to the impeller in order to improve the radial inflow caused when the mixed flow blower impeller 21 is used in a high load region.

That is, there has been a demand for the mixed flow blower impeller 21 to reduce the noise by controlling the tip vortex and to improve the static pressure by smoothing the inflow in the radial direction in a high load region.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a mixed flow blower impeller which achieves both low noise of a blade and improvement of a static pressure.

[0008]

According to the present invention, in order to achieve the above-mentioned object, the leading edge of the blade is defined by the shape of the rotation locus of the blade.
A curve that is concave toward the windward side near the midpoint between the hub and the outer peripheral end of the blade and a curve that is convex toward the windward side near the hub near the midpoint, and the radius of the blade The cross-sectional shape in the direction is formed as a concave curve with respect to the windward side from the vicinity of the midpoint of the blade to the windward side, and as a curve with a convex shape with respect to the windward side on the hub side from the vicinity of the midpoint.

With the above-mentioned structure, the generation of the tip vortex generated on the suction surface near the outer periphery of the blade due to the leakage flow from the pressure surface to the suction surface is promoted by the concave curved portion of the blade itself,
Noise can be reduced. In addition, the convex curved portions of the blades on the hub side can smooth the radial inflow flow in a high load region and simultaneously improve static pressure.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is directed to an oblique flow fan impeller provided with a plurality of thin blades on a substantially frustoconical hub. In the shape of the above, on the outer peripheral side from near the middle point between the hub and the outer peripheral end of the blade, it is formed into a concave curve with respect to the windward on the hub side from near the midpoint, and on the hub side with a convex curve with respect to the windward, The cross-sectional shape of the blade in the radial direction is formed into a concave curve with respect to the windward on the outer periphery side near the midpoint of the blade, and a convex curve with respect to the windward on the hub side from near the midpoint. With this, by the leakage flow from the pressure surface to the suction surface, the generation of the tip vortex generated on the suction surface near the outer periphery of the blade is promoted by the concave curved part of the blade itself, and the noise is reduced. In the convex curved part of the blade on the hub side, the radial inflow at high load It is of, it is possible to improve the static pressure.

According to a second aspect of the present invention, the blade is a thick blade, and the cross-sectional shape of the center line of the flow path connecting the middle point of the leading edge and the middle point of the trailing edge of the thick blade is set. , In which the ratio t / c of the maximum thickness t to the chord length c is in the range of 5 to 12%, whereby the thickness of the thick wing is smaller than that of a thin wing having a constant thickness. The blades having the airfoil shape can prevent flow separation, and can further reduce noise.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 is a plan view of a mixed flow fan impeller, FIG. 2 is a partial view showing a rotation locus of a blade of the impeller, FIG. 3 is a cross-sectional view taken along line AA of FIG. 1, and FIG. FIG. 5 is a schematic diagram showing an operation state, and FIG. 5 is a curve diagram comparing performance characteristics of the impeller with a conventional one.

As shown in the figure, the mixed flow blower impeller 1 is
The thin blades 2 are radially arranged on the outer periphery of the substantially frustoconical hub 3.
It is constituted by providing two sheets. Then, as shown in FIG. 4, the shaft of the motor 4 is fixed to the hub 3 of the mixed flow blower impeller 1 and is housed in an appropriate casing 5 to be rotated by the motor 4 so as to generate a blowing action. At this time, most of the air flows in from the leading edge 6 of the blade 2 shown in FIG. 1 and flows out from the trailing edge 7 to perform aerodynamic work.

Here, as shown in FIG. 2, the blade 2 has the shape of its rotation locus, and the leading edge 6 of the blade 2 is located near the midpoint X between the hub 3 and the tip (outer peripheral end) 8 of the blade 2. The tip 8 side is formed so as to have a concave shape with respect to the windward side (air flow), and the hub 3 side is formed so as to have a curve with a convex shape with respect to the windward side from near the midpoint X. Note that a line BB is a mid-point line (flow path center line described later) connecting a mid-point (intermediate point) between the hub 3 and the chip 8 on the front edge 6 and the rear edge 7, and a line CC is a rotation center line of the impeller. Show.

As shown in FIG. 3, the blade 2 has a cross section in the radial direction of the blade 2. The hub 3 side is formed so as to have a convex curve with respect to the windward side.

With the above configuration, the generation of the tip vortex generated on the side of the suction surface 9 near the tip 8 of the blade 2 due to the leakage flow of the airflow from the pressure surface 10 to the suction surface 9 reduces the concave shape of the blade 2 itself. The noise is reduced by promoting the curved portion of the curve, and the convex curved portion of the blade 2 on the hub 3 side facilitates the radial inflow that increases in the high load region, that is, the inflow from the tip 8 side. To improve the static pressure.

As described above, both noise reduction and improvement of static pressure in a high load region can be achieved.

Next, specific effects of the above configuration will be described with reference to FIG. FIG. 5 shows the static pressure characteristics and noise characteristics (A) of the mixed flow blower impeller using the thin blades of the present invention and the conventional mixed flow blower impeller. FIG.

That is, as shown in FIG. 5, at the open air volume point Q1 where the air volume is low, there is a low noise effect of 2 dB (A), and further, there is a low noise effect up to a region Q2 of about 68% of the open air volume. . Further, in the 60% area Q3 of the open air volume, the static pressure is 3%.
2% improvement.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a cross-sectional view taken along a flow channel center line BB in which the blade is a thick blade, and FIG. 7 is a radial cross-sectional view near the maximum thickness of the blade using the thick blade.

In the cross-sectional shape taken along the middle dotted line (flow path center line) BB connecting the middle point of the leading edge and the middle point of the trailing edge of the blade 12 of the thick wing shown in FIG. The ratio t / c of t to the chord length c connecting the middle point of the leading edge and the middle point of the trailing edge is 5 / c.
The mixed flow blower impeller 11 is configured in an airfoil shape having a range of about 12%.

Further, as shown in FIG. 7, the radial cross section of the blade 12 has a concave shape with respect to the windward side on the tip 14 side near the midpoint line BB of the blade 12, and a hub 13 with a hub 13 position near the midpoint line BB. On the side, it is formed in a curved shape convex to the windward side.

With this configuration, the generation of the tip vortex generated on the suction surface 15 side near the tip 14 of the blade 12 due to the leakage flow from the pressure surface 16 to the suction surface 15 is controlled by the concave curved portion of the blade itself. It promotes low noise.

The convex curved portions of the blades 12 on the hub 13 side facilitate the radial inflow that increases in a high load region, that is, the inflow of air from the tip 14 side, thereby improving the static pressure. ing.

As described above, it is the same as in the case of thin blades that achieves both reduction of noise and improvement of static pressure in a high load region. In this case, the blade 12 is compared with a thin wing having a constant thickness,
By forming the airfoil shape of a thick wing in which the ratio t / c between the maximum thickness t and the chord length c is 5 to 12%, separation of the flow from the blade 12 is prevented, and further noise reduction is achieved. can do. However, the low noise effect is exhibited when the ratio t / c is 5%, and the low noise effect is saturated when the ratio t / c is 12%. By the way, outside diameter Φ40
When a 0 mm mixed flow fan impeller uses thick blades having a ratio t / c of 9%, a low noise effect of 2 dB (A) has been obtained in experiments in comparison with thin blades.

These techniques are not limited to the mixed flow fan impeller, and the same effects can be obtained with an axial flow fan impeller.

[0030]

As is clear from the description of the above embodiment,
According to the first aspect of the present invention, the leading edge of the blade of the thin wing has a concave shape with respect to the windward side on the outer peripheral side from near the midpoint between the hub and the outer peripheral end of the blade in the shape of the rotational trajectory of the blade. On the hub side from the vicinity of the point, it is formed in a curved shape convex to the windward side, and the cross-sectional shape in the radial direction of the blade is concave from the windward side on the outer side near the midpoint of the blade. On the hub side from the vicinity, it is formed in a curved shape that is convex to the windward side. With this configuration, the blade tip vortex generated on the suction surface near the outer periphery of the blade due to leakage flow from the pressure surface to the suction surface Generation is promoted by the concave curved part of the blade itself to reduce noise, and the convex curved part of the blade on the hub side smooths radial inflow at high load area and improves static pressure. And at the same time have the effect.

According to a second aspect of the present invention, the blade is a thick blade, and the cross-sectional shape of the center line of the flow path connecting the middle point of the leading edge and the middle point of the trailing edge of the thick blade is Maximum thickness t and chord length c
And the thickness t / c is in the range of 5 to 12%, so that the thickness of the airfoil is larger than that of a thin blade having a constant thickness. Can be prevented, and noise can be further reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a mixed flow blower impeller according to a first embodiment of the present invention.

FIG. 2 is a partial view showing a rotation locus of a blade of the impeller.

FIG. 3 is a sectional view taken along line AA in FIG.

FIG. 4 is a schematic diagram showing an operation state of the impeller.

FIG. 5 is a curve diagram comparing the performance characteristics of the impeller and a conventional mixed flow blower impeller.

FIG. 6 is a sectional view of a mixed flow blower impeller according to a second embodiment of the present invention, taken along the center line of the flow path.

FIG. 7 is a radial cross-sectional view of the impeller near the maximum thickness of the blade.

FIG. 8 is a plan view of a conventional mixed flow blower impeller.

9 is a sectional view taken along line DD in FIG.

[Explanation of symbols]

 1,11 Mixed flow blower impeller 2,12 Blade 3,13 Hub 6 Front edge 7 Rear edge 8,14 Chip (outer peripheral end)

Claims (2)

[Claims] 1. A mixed flow blower impeller comprising a plurality of thin blades provided on a substantially frustoconical hub, wherein a leading edge of the blade is formed in a shape of a rotation locus of the blade and the hub and the blade. The blade is formed so as to have a concave curve with respect to the windward on the outer peripheral side from the vicinity of the middle point with the outer peripheral end of the blade, and a curve with a convex shape with respect to the windward on the hub side from near the middle point. The cross-sectional shape in the radial direction was formed so as to be a concave curve toward the windward on the outer peripheral side from near the midpoint, and to be a convex curve toward the windward on the hub side from near the midpoint. Mixed flow blower impeller. 2. A blade having thick wings, wherein a cross-sectional shape of a flow path center line connecting a middle point of a leading edge and a middle point of a trailing edge of the thick wing is defined by a maximum thickness t, a chord length c, The mixed flow blower impeller according to claim 1, wherein the blade has an airfoil shape having a ratio t / c in a range of 5 to 12%.