JPH045500A - Multiple blade blower - Google Patents

Abstract

PURPOSE:To set an axial blockage range small, and equalize the flow velocity at an exit a blade of an impeller along the blade width by bending the blade in the rotating direction to the axial direction on the side plate side. CONSTITUTION:A blade 2 of an impeller 1 is bent in the rotating direction to the axial direction on the side plate side. Air flowing axially to the blade 2 goes perpendicularly to the axially direction by this, so a blockage range is reduced. In addition, the velocity distribution at the exit of the impeller 1 is almost equalized for a blade width b2. A high performance and a large reduction of noise can thus be achieved for a multiple blade blower.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air blower such as a fan blower, and particularly to an impeller structure of a fan blower equipped with a centrifugal multi-blade impeller.

[Conventional technology]

The impeller shape of the conventional multi-blade blower was developed in 1985-1985
As described in Japanese Patent No. 597, a required number of blades are arranged at equal pitches in the circumferential direction between a disc-shaped main plate and an annular side plate facing the main plate. According to this structure, as described in Japanese Utility Model Application Publication No. 59-5797, the wind flows from the side plate side to the blade following an arcuate locus to the blade outlet, and the wind speed at the blade outlet is It was gradually getting faster from the side to the main board.

In other words, a velocity gradient occurred in the axial direction of the blade.

On the other hand, as described in Japanese Patent Application Laid-Open No. 64-8396, although the structure is similar to the conventional one, in order to uniformize the overall velocity distribution in the axial direction of the blade, that is, the outflow distribution, the main plate side There was also an impeller structure in which the length of the blade chord on the side plate side was different.

[Problem to be solved by the invention]

Utility Model Application No. 55-85597 or Utility Model Application No. 5957
The technique disclosed in Publication No. 97 does not take into consideration the speed gradient in the direction of the blade axis, and the impeller does not do any work, that is, a dead area (blower cage area) where the main flow does not flow occurs. There was a problem.

Furthermore, due to the occurrence of a velocity gradient, there is a problem in that a mixing loss of flows occurs due to this velocity difference. In addition, the high-speed flow of soil discharged from the impeller converts velocity energy into static pressure within the scroll, but unlike conventional impellers, the velocity and pressure at the blade outlet are invariant between the blade widths. In the case of a uniform flow, it flows to the exit of the scroll while making a complicated swirl inside the scroll, and a large mixing loss occurs along the way.
Significantly reduced the differential user effect of scrolling. As a result of the non-uniform flow at the outlet of these blades, the pressure at the scroll outlet also shows a low value, resulting in problems of low performance, low efficiency, and high noise.

On the other hand, the prior art disclosed in Japanese Patent Application Laid-Open No. 64-8396 is
Although the impeller was devised to solve the above problems,
As with conventional impellers, the actual flow of air flows along the suction cone on the suction side of the impeller, and the flow velocity increases as it approaches the suction cone and decreases as it approaches the center of rotation of the impeller. On the other hand, the flow velocity inside the impeller sinks to the flow velocity on the suction side and becomes a flow velocity that is suddenly and significantly reduced. For that reason,
A wide peeling area occurs in the axial direction near the side plate. Therefore, the main stream cannot flow close to the side plate near the side plate and flows obliquely to the axis of rotation, while the main stream near the center of rotation flows approximately at right angles to the center of rotation near the main plate. As a result, the speed on the main plate side increased, and the speed became slower toward the side plates. Moreover, in this invention, since the chord lengths of the side plate side and the main plate side are different, a wake occurs at the joint, which has an adverse effect on performance and noise.

On the other hand, according to what has been published in previous research, the relative flow of wind at the blade inlet has an incident angle in both the axial and radial directions. However, it was becoming impossible.

The purpose of the present invention is to correct the discrepancy in the relative flow incidence angle of the wind on the side of the blade side plate, to reduce the protrusion area in the axial direction of the impeller, to equalize the flow velocity Cmz at the blade outlet over the width b2, and to reduce the work of the impeller. It is an object of the present invention to provide an impeller for a multi-blade blower with increased capacity, high efficiency, and low noise.

[Means to solve the problem]

In order to achieve the above object, the present invention has blades on the side plate side bent in the rotational direction with respect to the axial direction.

[Effect]

The air flow in the multi-blade blower of the present invention is that, conventionally, the air near the suction cone flows along the axial direction of the blades toward the main plate side, but according to the shape of the present invention, the air near the suction cone flows in the axial direction. Since the blade shape on the side plate side has a bent portion in the direction of rotation, air flows in a direction perpendicular to the axial direction, instead of the air flowing in the axial direction of the conventional blade. Therefore, the dead area (blockage area) where the main flow does not flow, which conventionally occurred on the side plate side of the blade outlet, is reduced, and the velocity distribution at the impeller outlet becomes a substantially uniform distribution over the blade width b2.

Further, the relative flow of the wind has an incident angle to the blades, and in particular, the side plate side has an angle of inclination toward the rotational direction with respect to the axial direction, so the shape of the present invention allows the relative flow of the wind to flow smoothly.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view of a blower using the impeller of the present invention, and FIG. 2 is a sectional view taken along line n-n-n in FIG. 1.

A multi-blade blower has an impeller 1 and a scroll 20 as shown in Figure 1.
and a motor 30 for rotating the impeller 1. The impeller 1 further includes a plurality of blades 2 and a main plate 3 . It is composed of side plates 4. The air flow in the multi-blade blower flows along the suction cone 21 on the suction side of the impeller, and the flow velocity increases as it approaches the suction cone 21 and decreases as it approaches the rotation center of the impeller.

FIG. 3 shows the shape of the blades 2 of the impeller 1 of the present invention.

This shape is Δ in the axial direction from the side plate side of the blades 2 of the impeller 1.
The blade has a shape that advances by Δp in the rotational direction from the position b.

That is, the blade shape on the side plate side is a three-dimensional blade shape bent in the rotation direction, whereas the blade shape on the main plate side is a two-dimensional blade shape as in the conventional case.

FIG. 4 is a diagram showing the flow of air in the impeller 1.

Radial velocity component Cm of the flow velocity on the outer diameter of the impeller 1
2 with respect to the blade outlet width (dimension b2). As mentioned above, the distribution in the conventional structure is C112 near the side plate.
was small, and CIIZ increased as it approached the main plate 4.

According to the blade shape of the present invention, since the blade side plate side is bent in the rotational direction with respect to the axial direction, as the blade rotates, the streamline 10a near the side plate 4 moves along the trajectory that conventionally flowed. Compared to this, it is almost perpendicular to the center of rotation. In other words, in the conventional air flow, the flow would slide from the side plate side of the blade to the main plate side, but because the blade has a bent part, the wind does not slide suddenly at that point, and instead flows toward the outer circumferential surface of the side plate side. On the other hand, since air is collected by bending and flows toward the outer diameter of the blade, the amount of air on the side plate side increases.

On the other hand, when comparing the streamline 10b with the conventional one, the slippage is reduced and the flow moves toward the side plate side. Streamline 10
As in the conventional case, C112 gradually becomes a flow almost perpendicular to the center of rotation, and the distribution of C112 at the impeller outlet shows a fairly uniform distribution over the blade width b2.

This reduces the mixing loss due to the Cox speed difference at the impeller outlet, as well as the swirling and mixing loss within the scroll.

The relative flow of wind will be explained using FIG. 5. Fifth
As shown in the figure, the wind flow, especially the relative flow, has complicated angles. That is, the combined speed of the circumferential speed U1 of the inner diameter of the blade and the absolute speed C1 of the inner diameter of the blade becomes the relative speed at the blade inlet.

Also, the absolute velocity has an axial component Cx 1 and a radial component C1
11, and the relative velocity, which is the composite velocity of the circumferential velocity, naturally has an incident angle with respect to the axial direction.

The shape of the blade according to the present invention is bent in the rotational direction with respect to the axial direction. In other words, since the relative velocity is bent in the same direction as the incident angle with respect to the axial direction, the relative flow of the wind enters the blade smoothly, so there is no loss due to the wind colliding with the blade. This increases the efficiency of the blower.

FIG. 6 is a perspective view showing the shape of the blade and the flow of air in another embodiment of the present invention.

The blades on the main plate side of the impeller are blades that advance in the rotational direction from the side plate side, and these blades are also provided with bent portions in the rotational direction with respect to the blades on the side plate side.

That is, the shape of the inner and outer diameter of the blade on the side plate side is a three-dimensional blade shape bent in the rotation direction, whereas the blade shape on the main plate side is a two-dimensional blade shape as in the conventional case.

Let's consider the flow of wind in this example in the same way. In this embodiment as well, as in the embodiment, the blade shape is such that the side plate side is bent in the rotation direction with respect to the axial direction on the inner diameter side of one blade, so as the blade rotates, the streamline 10a near the side plate 4 is Compared to the conventional trajectory, the flow is faster with respect to the center of rotation.

It becomes vertical. This makes it possible to reduce the number of protrusion parts, resulting in improved performance and lower noise.

According to the present invention, a large improvement can be obtained in terms of aerodynamic performance and noise, so the degree of bending of the blade 2 was experimentally investigated.

The degree of bending is defined as follows.

b2 Width of the two blades Δb: Position p when bent from the side plate side toward the axial direction: Pitch width of the blade Δp: Dimensional data when bent in the direction of rotation is rendered dimensionless, so Δb / b 2 and Δp
Organized with /p.

Figure 7 shows Δp/p of blade 2 and the highest efficiency point η of the multi-blade blower.
The experimental results of the relationship between ++aX and the specific sound level SLS at the highest efficiency point are shown.

Here, Δp/p=1.0 means a shape bent in the rotation direction by exactly -pitch.

These are experimental results for a multi-blade blower with Δp/p=0.5, 1.0.1.5. From Figure 7, the highest efficiency point η, □ is Δ
The specific noise level SLS was highest near p/p=0.5, and good results were also obtained near Δp/p=0.5. Conversely, when Δp/p is 1.5, the fan efficiency is lower and the specific noise level is higher than in the case of a conventional impeller (ΔP/P = 0', i.e., there is no bent part). .

From the above effects, by providing the impeller with a slightly bent portion compared to the conventional impeller Δp/p=o, the total pressure at the same air flow rate at the same rotation speed of the blower increases, and the fan efficiency increases. Moreover, the noise level at that time is also reduced, making it an effective means.

This is because the fan efficiency and specific noise level are at their highest when Δp/po = 0, 5, and the bending angle at this time matches well with the air flow.

If the angle of the bent portion becomes larger than this, the wind flow will be shifted from the bent portion, and the efficiency and hole noise will be adversely affected. At around Δp/po=1.5, the conventional impeller (Δ
p/p=o), or worse.

〔Effect of the invention〕

According to the present invention, the dead area (blockage area) where the impeller does not work near the blade side plate is reduced, and furthermore, the distribution of the speed Cm2 at the impeller outlet shows a substantially uniform distribution over the blade width b2, thereby The mixing loss due to the speed difference of C-Y2 at the impeller exit, and furthermore, the swirling and mixing loss in the scroll become sharper.

As a result, the characteristics of the multi-blade blower of the present invention are effective in obtaining higher performance and significantly reduced noise compared to conventional characteristics.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along arrow ll-n-4 in FIG. 1, FIG. 3 is a perspective view of a blade of the present invention, and FIG. 5 is a flow diagram of the impeller of the present invention, FIG. 6 is a perspective view of an impeller of another embodiment of the present invention, and FIG. 7 is a perspective view of the multi-blade blower of the present invention. FIG. 2 is an explanatory diagram of experimental results. 1... impeller, 2... impeller, 3... main plate, 4...
- Side plate, 10a, 10b, 10c - wind flow, 20 - scroll, 21 - suction cone, 30 - motor.

Claims (1)

[Claims] 1. In a multi-blade blower equipped with an impeller composed of a plurality of forward-facing blades, a main plate, and a side plate, the blades on the side plate side of the impeller are bent in the rotational direction with respect to the axial direction. A multi-blade blower characterized by having provided blades.