JPH1089289A - Impeller for axial flow blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impeller for an axial flow blower to reduce the generation of noise due to a wake in an upper stream spot and interference noise of a vane, remarkably improve the strength of a vane, reduce the thickness and the warp of the vane, and eliminate a need for reinforcement. SOLUTION: A ratio of a hub diameter D1 to the outside diameter D1 of an impeller is 30-40%, the center of a vane having an arbitrary diameter is situated on a circular arc or an n-degree curve to interconnect the center of the section of a vane at a hub 2 and the center of the section of the vane. As seen from the front of the impeller, an angle between a straight line to interconnect the center of a rotary shaft and the center of the vane 1 at the hub 2 and a straight line to interconnect the center of the rotary shaft and the center of the vane 1 having an impeller outside diameter is 50-55 deg.. The center of the vane 1 having an arbitrary diameter is situated on a straight line or a circular arc or an ndegree curve to interconnect the center of the vane 1 at the hub 2 and the center of the vane at the outside diameter Dt of the impeller on a meridian plane, and an angle between a straight line to interconnect the center of the vane at the hub 2 and the center of the vane 1 at the impeller outside diameter Dt and a perpendicular to the center of the rotary shaft is 7.5-12.5 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller of an axial blower used for an air conditioner, a ventilation fan and the like.

[0002]

2. Description of the Related Art An impeller of an axial blower used for an outdoor unit of an air conditioner, a ventilation fan, and the like is required to reduce noise in order to improve comfort and social environment. Conventionally, in this type of impeller, in order to achieve low noise, at the same time as the blade element center of the impeller is inclined toward the gas suction side,
A so-called forward leaning, forward impeller that has advanced in the rotational direction is employed.

FIG. 12 is a view showing an example of a conventional forwardly inclined, forward impeller. FIG. 12 (a) is a front view showing a part of the impeller, and FIG. 12 (b) is a part of the impeller. FIG. In FIG. 12, reference numeral 11 denotes an impeller wing, and reference numeral 12 denotes a blade.
Is a hub to which the wings 11 are attached. As a feature of the wing 11, the wing surface is greatly twisted forward to the gas suction side while being spatially twisted, forming a three-dimensional curved surface shape. The forward inclination angle (δ _Z ) is 12.5 to 30 ° and the advance angle (δ _Z )
(θ) is considered to have low noise when the angle is in the range of 15 to 35 ° (θ is indicated by subscript in the figure).

[0004]

However, the forward inclination angle is set to 1
When it is set to 2.5 to 30 °, the impeller becomes longer in the axial direction,
There are dimensional problems, such as the size of the air conditioner and ventilation fan to be incorporated becoming larger in the axial direction. When incorporating this axially long impeller into a limited space such as an air conditioner,
The tip of the wing approaches coils and other piping, causing wake noise from the wake and the wings, and some impellers generate wake on the upstream side even with low noise. There is a problem that noise is increased as a device incorporated in such a case. In addition, there is a problem that the size of the device increases in the axial direction as much as the impeller is moved away from the coil or the like in order to reduce noise.

[0005] Further, since the wing that has been tilted forward and advanced does not have the center of gravity of the wing on a vertical line drawn from the centroid of the wing cross section at the hub of the impeller to the rotation axis and is eccentric by the amount of forward tilt and advance, FIG.
As shown in (1), the bending moment applied to the wing section of the hub increases due to the centrifugal force generated by the rotation, and the strength decreases with respect to the centrifugal force. Therefore, there are problems such as operation at low speed, the need to increase the thickness and warpage of the hub blade section, and the need to reinforce the hub blade section. In addition, there is a problem that increasing the thickness and the warpage of the wing may increase noise. Further, when reinforcement is applied to the base of the wing 11 as shown in FIG. 14, there is a problem that noise is increased due to a vortex generated from the reinforcement portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and when incorporated into a device, the noise due to the interference between the wake and the blades on the upstream side can be reduced, or the device can be controlled with the same level of noise as before. Axles that can be downsized in the direction and the strength of the wings are dramatically improved, and can be used without any problem even when the advancing angle is 50 ° or more, and the thickness and warpage of the wings can be reduced and no reinforcement is required. An object of the present invention is to provide an impeller of a blower.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to an impeller of an axial flow blower having a plurality of blades and a hub to which the blades are attached, and an outer diameter of the impeller. When the impeller is viewed from the front and the center of the cross-section of the blade at the hub and the center of the cross-section of the blade at the outer diameter of the impeller are an arbitrary diameter on an arc or n-th order curve when the impeller is viewed from the front. When the impeller is viewed from the front, the angle between the straight line connecting the center of the rotation axis and the center of the blade at the hub and the straight line connecting the center of the rotation axis and the center of the blade at the outer diameter of the impeller is 50. In the so-called meridional plane, in which the impeller is projected on one plane including the center of the rotation axis, a straight line or an arc or an nth-order curve connecting the center of the blade at the hub and the center of the blade at the outer diameter of the impeller. The center of the wing at the diameter of , In which the angle of the normal to the straight line with the rotation axis center line connecting the centers of the blades at the center and the impeller outside diameter of the blade in the hub, characterized in that a 7.5 to 12.5 °.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an impeller of an axial blower according to the present invention will be described below with reference to FIGS. 1 and 2 are views showing a basic configuration of an impeller of an axial blower according to the present invention. FIG. 1 is a front view showing a part of the impeller, and FIG. 2 is a meridional view showing a part of the impeller. It is.

1 and 2, reference numeral 1 denotes an impeller blade, and reference numeral 2 denotes a hub to which the blade 1 is attached. The ratio of the outer diameter Db of the hub 2 to the outer diameter Dt of the impeller is 30 to
It is set to 40%. That is, Db = (0.3-0.
4) It is set to × Dt. In the wing 1, as shown in FIG. 1, the impeller is viewed from the front, and an arbitrary arc or n-dimensional curve C connecting the center Oa of the wing cross section at the hub and the center Ob of the wing cross section at the outer diameter of the impeller is used. The center of the wing at the diameter of
the straight line L ₁ connecting the center Oa of the blade in the o and the hub 2, an angle δθ of the straight line L ₂ connecting the center Ob of the blade in the rotation axis center Oo and the impeller outside diameter is set to 50-55 °. An arc or an nth-order curve connecting the centers of the blades is a straight line distance Oa-Ob in a direction opposite to the rotation direction with respect to a straight line connecting the center Oa of the cross section of the blade at the hub and the center Ob of the blade cross section at the outer diameter of the impeller. Is set to swell by 15 to 25%.

As shown in FIG. 2, the center Oc of the wing 1 in the hub 2 and the center Od of the wing in the outer diameter of the impeller are connected on a so-called meridional plane in which the impeller is projected on one plane including the center of the rotation axis. A straight line, an arc or an n-order curve has the center of the blade at an arbitrary diameter, and a straight line L connecting the center Oc of the blade at the hub and the center Od of the blade at the outer diameter of the impeller.
₃ and the angle [delta] _Z of a perpendicular line L ₄ relative to the rotation axis center Oo is set to 7.5 to 12.5 °. When an arbitrary blade section in the meridian plane is arranged in an arc or an nth-order curve connecting Oc and Od, a linear distance Oc to Od of 0 to 10 in the downstream direction in the flow direction with respect to the straight line connecting Oc and Od. % Is set to swell.

3 and 4 are views showing the shape of the blade of the impeller of the present invention. FIG. 3 is a perspective view of the blade and the hub, and FIG. 4 is an isometric view of the cylindrical surface of the hub of the blade with respect to the plane. It is a map. As shown in FIGS. 3 and 4, in the blade of the present invention, perpendiculars La, Lb, Lc, and Ld drawn from the center of gravity A, B, C, and D of the cross section of the blade at an arbitrary diameter to the center Oo of the rotation axis. When intersections A ', B', C ', and D' with the cylindrical surface of the hub are conformally mapped on the plane of the cylindrical surface of the hub, they pass through the centroid z of the cross section of the blade at the hub, and the tip and the rear of the blade. whether on the straight line L ₆ parallel to the straight line L ₅ connecting the end, the intersection point Wc 'of the cylindrical surface of the perpendicular Lwc a hub down to the rotation axis center Oo from the center of gravity Wc of the whole wing, flat cylindrical surface of the hub When isometric mapping to
It is on a straight line parallel to L ₆ between the straight line L ₅ which connects the front end and the rear end of the centroid z street wing section of the blade at the hub. Then, the cross section of the wing at an arbitrary diameter has an airfoil shape or an equal thickness shape along a so-called camber line of the airfoil.

5 and 6 are views showing the shape of the blade of the impeller of the present invention. FIG. 5 (a) is an isometric map of the outer diameter of the blade of the impeller onto the plane of the cylindrical surface. (B) is an isometric view of the cylindrical surface of the wing hub on the plane, and FIG. 6 is a diagram showing a cross section of the wing. As shown in FIG. 5, in the blade of the present invention, the mounting angle of the blade is B∞t = 20 to 30 ° at the outer diameter of the impeller;
In the hub, B〜b = 30-45 °. As shown in FIG. 6, L is a chord length, f is a camber line (center line) warp (max) of the wing, d is a maximum length of the wing,
Also, if t is the pitch of the blade, D is the diameter, and Z is the number of blades,
t = πD / Z, and in the blade of the present invention, the so-called chord ratio t / L at an arbitrary cross section is 1.1 to 1.
5, the warp f / L is 4 to 12%, and the maximum thickness d of an arbitrary cross section
/ L is set to 1.5 to 8%.

FIGS. 7 and 8 are explanatory views showing a comparison of the installation state of the impeller of the axial blower of the present invention and the impeller of the conventional axial blower. In FIG. 7, the impeller of the present invention is indicated by a solid line, and the conventional impeller is indicated by a two-dot chain line. In the present invention, instead of setting the forward tilt angle of the impeller to a relatively small angle of 7.5 to 12.5 °, the advance angle is set to 50 to 55 °.
And the impeller alone reduces the noise to the conventional forward tilt angle of 12.
5 to 30 °, the same level as the advance angle of 15 to 35 °, and when installed on a device having a wake generator 5 such as a coil on the upstream side, the amount by which the tip of the blade moves away from the wake generator 5, Since the interference noise between the wake and the blade from the upstream is reduced as compared with the case of using the conventional impeller, the noise can be reduced as a device with a built-in fan, or the device can be moved in the axial direction with the noise level kept the same as before. Can be made smaller.

Conventional forward tilt angle 12.5-30 °, advance angle 1
Even if the impeller alone has low noise, the impeller configured at 5 to 35 ° is installed on the downstream side of a coil or the like. When approaching, interference noise between the wake and the wing is generated, resulting in increased noise.

The magnitude of the interference sound depends on the width and flow velocity of the wake, such as a coil. However, qualitatively, the relationship between the distance between the wake generator and the impeller and the noise is shown in FIG. When the two are close to each other, the noise increases as the frequency expressed by the number of blades times the rotation frequency and a so-called rotation noise having a frequency that is an integral multiple of the frequency. When the forward inclination angle is limited to a range of 7.5 to 12.5 ° like the impeller of the present invention, as shown in FIGS. 7 and 8, T = Htan (12. 5 to 30 °) −Htan (7.5 to 12.5 °) The tip of the impeller can be kept away from the wake generator 5 by a length of ≒ 0 to 0.36H. The effect that noise can be reduced compared to the conventional one by ΔSPL is obtained.

On the other hand, FIG. 10 shows a relative comparison between the forward tilt angle and the advance angle of the impeller and the noise. FIG. 10 shows that the horizontal axis represents the advance angle δθ,
The vertical axis indicates the relative noise level, is the forward inclination [delta] _z those parameters. As is clear from FIG. 10, even if the forward inclination angle is 7.5 to 12.5 °, if the advance angle is set to 50 ° or more, there is no difference between the impeller alone and the conventional one. Therefore, if it is installed in a device that does not take up space in the axial direction downstream of the wake generator 5, ΔSPL
Only the noise can be reduced. Alternatively, the effect of reducing the size in the axial direction by T compared to the case of using the conventional one at the same noise level is obtained.

The conventional forward tilting forward wing is eccentric by the amount of forward tilting and forward movement without the center of gravity of the blade on a vertical line drawn from the centroid of the blade cross section at the hub of the impeller to the rotation axis.
A large bending moment is applied to the wing 11 as shown in FIG.
For this reason, as described above, the blade thickness is increased, the blade warpage is increased, and reinforcement is provided to increase the section modulus and increase the strength.However, these methods have a large wake width of the blade. Noise increases to become.

In order to solve this problem, in the present invention, as shown in FIG. 3 and FIG. 4, a perpendicular drawn from the center of gravity A, B, C, D of the cross section of the blade at an arbitrary diameter to the center Oo of the rotation axis. When the intersections A ', B', C ', D' of La, Lb, Lc, Ld and the cylindrical surface of the hub are conformally mapped on the plane of the cylindrical surface of the hub, the centroid z of the cross section of the blade at the hub is obtained. or it is on the straight line L ₆ parallel to the straight line L ₅ which connects the front end and the rear end of the street wing intersection Wc 'of the cylindrical surface of a perpendicular Lwc a hub down to the rotation axis center Oo from the center of gravity Wc of the whole wing, when conformal mapping the cylindrical surface of the hub in a plane, arranged on the straight line L ₆ parallel to the straight line L ₅ which connects the front end and the rear end of the through wing centroid z of the wing cross-section of the hub. As a result, the bending moment generated by the load due to the centrifugal force does not act at all in the direction where the section modulus of the blade section of the hub is small, but acts only in the direction where the section modulus is large.

For the sake of simplicity, when the same load is applied to one arc blade, FIG. 11 shows a comparison between the above-described configuration and the configuration other than the above. FIG. 11 is an isometric view of the cylindrical surface of the hub, and FIG. 11A shows an impeller of the present invention;
FIG. 11B shows a conventional impeller. As shown in FIG. 11A, f / L = 8% and d / L = 6%. r (1-
cos α) = 8.2, 2 × rsin α = 100 and r = 16
0.25, α = 0.3173 rad. Section modulus Z ₁ around the X axis ^{_{is, Z 1 = {r 2 t}} (α 2 + αsinα · cosα-2sin 2 α)} / (α-sin α) = 1300 Y axis of the section modulus Z is, Z = r ² t {(α / sinα) -cosα} = 1030
7 Assuming that the load = 100, in the present invention, σ _b1 = (100 × 80) / 1030
7 = 0.78 In the conventional example, σ _b2 = (100 × 70) / 1030
7+ (100 × 25) /1300=2.6 Although the example shown in FIG. 11 is an extreme example focusing only on the bending moment, the stress in the impeller of the present invention is 30% of that of the conventional example, and is the same. Assuming that stress is applied, the impeller of the present invention can rotate at 1.8 times the rotation speed. Further, assuming that the impeller rotates at the same rotational speed, the impeller of the present invention can reduce the plate thickness to 30% of the conventional example.

[0020]

As described above, according to the present invention,
Conventionally, it is possible to use the advancing angle of 50 ° or more without any problem in strength, and a low advancing angle (7.5 to 12.5 °) and the same level of noise reduction as a large advancing angle (12.5 to 35 °) can be achieved. As a result, the impeller can be made smaller in the axial direction, and when incorporating it into equipment, the noise caused by interference between the upstream wake and the blades can be reduced, or the equipment can be made smaller in the axial direction while maintaining the same level of noise as before. Can be

According to the present invention, the cross section of the blade can be further reduced by using a known blade type or a plate-shaped blade having an equal thickness along a camber line of the blade type.

Furthermore, according to the present invention, since the bending moment acts only in the direction in which the section modulus of the blade section of the hub is large, the strength is dramatically improved, and even if the advancing angle is 50 ° or more, it can be used without any problem. In addition, the thickness and warpage of the blades can be reduced, and no reinforcement is required, so that noise due to these wakes can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an impeller of an axial blower according to the present invention, and is a front view showing a part of the impeller.

FIG. 2 is a meridional view showing a basic configuration of an impeller of the axial blower according to the present invention, showing a part of the impeller.

FIG. 3 is a perspective view of a blade and a hub in the impeller of the axial blower of the present invention.

FIG. 4 is an isometric view of the circumferential surface of the hub of the wing onto the plane.

FIG. 5 is an isometric map of blades in an impeller of an axial blower according to the present invention.

FIG. 6 is a view showing a cross section of a blade in an impeller of the axial blower of the present invention.

FIG. 7 is an explanatory view showing a comparison between the impeller of the axial blower of the present invention and a conventional axial impeller.

FIG. 8 is an explanatory view showing a comparison between the impeller of the axial blower of the present invention and a conventional axial impeller.

FIG. 9 is a diagram illustrating a relationship between a distance between a wake generator and an impeller and noise.

FIG. 10 is a diagram showing a relative comparison between the forward tilt angle and the advance angle of the impeller and noise.

FIG. 11 is a diagram showing a comparison between the one of the present invention and another when the same load is applied to a single-arc blade.

12A and 12B are views showing an example of a conventional forwardly inclined, forward impeller, FIG. 12A is a front view, and FIG. 12B is a meridional view.

FIG. 13 is a diagram showing a bending moment applied to a conventional wing by centrifugal force.

FIG. 14 is a diagram showing an operation when reinforcement of a conventional wing is performed.

[Explanation of symbols]

Reference Signs List 1 blade 2 hub 5 wake generator Dt impeller outer diameter Db hub outer diameter δθ advancing angle δ _z forward tilt angle A, B, C, D Center of gravity of blade section at arbitrary diameter Wc Center of gravity of entire blade z Section of blade section Conscience

Claims (3)

[Claims] 1. An impeller of an axial blower comprising a plurality of blades and a hub to which the blades are attached, wherein a ratio of a hub diameter to an outer diameter of the impeller is 30 to 40%. Viewed from the front, an arc or n connecting the center of the cross section of the blade at the hub and the center of the cross section of the blade at the impeller outer diameter
There is a center of the blade at an arbitrary diameter on the next curve, and a straight line connecting the center of the rotating shaft and the center of the blade at the hub, and a straight line connecting the center of the rotating shaft and the center of the blade at the outer diameter of the impeller when the impeller is viewed from the front. In the so-called meridional plane in which the impeller is projected on one plane including the center of the rotation axis, a straight line or an arc or n connecting the center of the blade at the hub and the center of the blade at the outer diameter of the impeller. The center of the blade at an arbitrary diameter is on the next curve, and the angle between the straight line connecting the center of the blade at the hub and the center of the blade at the outer diameter of the impeller and the perpendicular to the center of the rotation axis is 7.5 to 12.5 °. An impeller for an axial blower, characterized in that: 2. The intersection of a vertical line drawn from the center of gravity of the cross section of the blade with an arbitrary diameter to the center of the rotation axis and the cylindrical surface of the hub when the cylindrical surface of the hub is conformally mapped to a plane. The intersection of the hub's cylindrical surface with a vertical line passing through the centroid of the cross section and parallel to the straight line connecting the tip and rear ends of the wing or the center of rotation from the center of gravity of the entire wing and the hub's cylindrical surface When the isometric mapping is performed on a plane, it is on a straight line that passes through the centroid of the cross section of the wing at the hub and is parallel to the straight line that connects the tip and the rear end of the wing. The impeller of an axial flow blower according to claim 1, wherein the impeller has an equal thickness along an airfoil so-called camber line. 3. The mounting angle of the wing is 20 to 30 ° at the impeller outer diameter and 30 to 45 ° at the hub, and the so-called chord ratio t / L at an arbitrary cross section is 1.1 to 1.5.
Warpage f / L is 4 to 12%, maximum thickness d / L of any cross section
Is 1.5 to 8%.
The impeller of the axial blower described.