CN208348150U - A kind of small-sized multi-wing centrifugal exhaust fan of highly effective low noise and impeller - Google Patents

Abstract

The utility model embodiment discloses a kind of impeller of small-sized multi-wing centrifugal exhaust fan of highly effective low noise, and by making blade twist and layback, so that impeller blade inlet angle is gradually changed according to axis direction, blade interior flowing is more reasonable；It is thickeied by blade bottom, increases blade strength and stability, while increased exit angle, reducing outlet flow size, increase outflow wind speed and wind pressure；To improve flowing and reducing the reflux between hub disk and spiral case gap, hub disk is changed to band conical ring by circular ring shape.This secondary design improves runner characteristic, reduces impeller blade to the percussion of air-flow, reduces noise and reduce loss.

Description

A small multi-blade centrifugal exhaust fan and impeller with high efficiency and low noise

technical field

The utility model relates to an exhaust fan, in particular to a small multi-blade centrifugal exhaust fan with high efficiency and low noise.

Background technique

With the rapid development of China's economy and technology and the improvement of people's living standards, China's home appliance market is also changing with each passing day. Exhaust fans have been more and more widely used in various industries, and consumers have higher and higher requirements for the quality and performance of exhaust fans. It is hoped that the exhaust fan can meet the requirements of low noise, high efficiency and small size while meeting the flow rate. There is a corresponding relationship between these parameters. Due to its high pressure coefficient, large flow coefficient and small volume, the multi-blade centrifugal exhaust fan has been used as the first choice for household exhaust fans.

Because the fan theory is not yet perfect, the internal flow field of the fan is complicated and difficult to describe, especially the design of small centrifugal exhaust fans often relies on empirical data. The traditional fan design method is based on the functional requirements of the product, the designer proposes a design plan based on experience, analyzes and experiments on the given party, and seeks the final feasible solution according to the product requirements.

The performance parameters of the fan (flow rate, wind pressure, noise and efficiency) mainly depend on the flow quality of the fan channel. The multi-blade centrifugal fan is mainly composed of three parts: a collector, an impeller and a volute. The function of the collector is to guide the gas. Impeller; the impeller mainly does work on the gas, and the motor drives the impeller to do work on the gas; the volute mainly plays the role of gas collecting, guiding and diffusing, and radiates noise through the surface of the volute. Among them, the impeller parameters have the most critical influence on the centrifugal exhaust fan, including the ratio of the inner and outer diameters of the impeller, the width (height), the diameter of the blades, the installation angle of the inlet and outlet, and the number of blades.

At present, the most researched by domestic researchers is the influence of impeller performance parameters on fan flow, pressure, noise and efficiency. Because of the complex shapes of the impeller and the volute, the cost of mold making is high, and most of the research is based on theoretical research or through software simulation by establishing fluid equations. At present, most impellers on the market use theoretical design formulas, but because of the wide variety of fans, even the same type of fan has many subdivisions, and the theoretical calculation formula is not fully applicable. At present, the blades of many centrifugal exhaust fans on the market are designed as single arc straight blades. The vane runner is the key position for the air flow to transition from the air inlet to the air outlet. Some changes should be made to the shape of the vane according to different working conditions to reduce aerodynamic noise and energy loss.

Utility model content

The technical problem to be solved by the embodiments of the present invention is to provide a small multi-blade centrifugal exhaust fan with high efficiency and low noise. It can make the exhaust fan more in line with the law of the flow field, reduce noise and improve efficiency.

In order to solve the above technical problems, the embodiment of the present utility model provides an impeller of a small multi-blade centrifugal exhaust fan with high efficiency and low noise, including blades, the leading edge direction of the blades is twisted and pitched back along the trailing edge direction, and the twist angle It is 8°～12°, and the back angle is 2°～6°.

Further, the inlet angle of the blade is in a circular arc structure.

Further, the angle range of the inlet angle of the blade is 40°˜50°.

Further, the angle range of the outlet angle of the blade is 165°˜175°.

Further, the distance between the flow channels between the blades is 6mm˜8mm.

Further, the chassis at the root of the impeller is chamfered at an angle of 6° to 12°.

Further, the radius of the blade arc is:

Among them, D2 is the outer diameter _of the impeller, D1 is the inner diameter of the impeller, _β2 is the angle of the outlet angle _of the impeller, _β1 is the angle of the inlet angle of the impeller, R1 is the inner radius _of the impeller, and _R2 is the outer radius of the impeller.

Further, the radius of the center arc of the impeller is

Further, the upper half of the blade is twisted and set back, and the lower half of the blade is drafted and thickened and set back.

The embodiment of the utility model also discloses a small multi-blade centrifugal exhaust fan with high efficiency and low noise, which includes the impeller of the above scheme.

Implementing the embodiment of the present utility model has the following beneficial effects: the present utility model makes the impeller blade inlet angle gradually change according to the axis direction by twisting and backing the blade of the impeller; by thickening the bottom of the blade, not only the strength and stability of the blade are increased, At the same time, the outlet angle is increased, the outlet flow channel size is reduced, and the outflow wind speed and wind pressure are increased. This design improves the flow channel characteristics, reduces the impact of the impeller blades on the airflow, reduces noise and reduces losses.

Description of drawings

Fig. 1 is the structural representation of the cross section of the blade of the present invention;

Fig. 2 is the overall structure schematic diagram of the blade of the present utility model;

FIG. 3 is a schematic structural diagram of the bottom of the impeller of the present invention being chamfered.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clear, the present utility model will be further described in detail below with reference to the accompanying drawings.

Refer to the schematic structural diagram shown in FIG. 1 .

An impeller of a small multi-blade centrifugal exhaust fan with high efficiency and low noise according to the embodiment of the present utility model includes blades arranged on the circumference.

The airflow of the exhaust fan enters from the collector, enters the impeller chamber, enters the blade flow channel through the front edge of the blade, and finally enters the flow channel of the impeller and the volute from the rear edge of the blade and flows out through the outlet. During the entire flow of the airflow, the velocity of the airflow is a composite velocity, and its velocity and direction are always changing, as shown in the following formula:

in, is the airflow velocity vector, is the axial component of the airflow velocity along the impeller, is the circumferential component of the airflow velocity along the impeller is the radial component of the airflow velocity along the impeller.

Before the airflow enters the collector, the circumferential speed of the airflow changes very little. The circumferential speed changes a lot near the edge of the collector, and the area near the axis is small and does not change much. At this time, the main speed of the airflow is the axis. to speed. When the airflow enters the collector, the circumferential speed and radial speed begin to increase, and the change is faster the closer to the leading edge of the blade. Therefore, when the airflow enters the blade flow channel, the airflow speed and direction are always changing along the axial direction, which requires the inlet angle β ₁ of the blade to be a changing process along the axial direction. At the beginning, when the airflow enters the impeller, the circumferential speed is small, and the inlet angle β ₁ can be larger, which can make the airflow enter the blade flow channel better. As the axial and circumferential velocity increases gradually, the angle of attack of the airflow on the blade becomes smaller, and the inlet angle β1 decreases accordingly to reduce the impact of the airflow on the blade, as shown in Figure ₁ .

In order to solve the above technical problems, through the blade twist and the blade back pitch, it is suitable for the blade torsion angle to be about 80 degrees to 120 degrees (this embodiment is preferably the blade torsion angle of 100 degrees), and the blade back pitch angle of 20 degrees to 40 degrees is suitable ( In this embodiment, the blade rear elevation angle is preferably 30 degrees), as shown in FIG. 2 .

The total blade length H (equal to the impeller height h) is 70mm, and the effective flow width at the impeller inlet is about 0.75 of the blade width. The blade is designed in sections, 50~60mm (take 55mm) at 3/4 of the upper half, twist 10° along the direction of rotation, and tilt back 3°, as shown in Figure 2. The 25mm at the 1/4 of the lower half is thickened with straight blades (thickening by draft, draft angle 1°), and the back is 3°. In addition to twisting and pitching back, the blade of this embodiment also chamfers the inlet side of the blade, as shown in FIG. 2 .

Considering the overall size of the exhaust fan, in order to achieve the same flow and pressure, the installation size should be reduced as much as possible, and the noise should be reduced at the same time. The outer diameter D ₂ of the impeller is Φ126mm, the inner diameter D ₁ is 102 mm, and the inner diameter to outer diameter ratio D ₁ /D ₂ =0.81. The impeller height h=(0.4-0.6)D ₂ , taking h=70mm, the outlet angle β ₂ =170°, and the inlet angle β ₁ =42°.

The radius of the blade arc is:

The radius of the center arc of the impeller is

In order to lengthen the acceleration flow passage of the blade outlet, the inlet flow passage of the blade should be shortened accordingly, and a sufficiently large outlet angle β ₂ and inlet angle β ₁ should be ensured. Therefore, by changing the blade arc radius R _k and the impeller center arc The radii R ₀ are respectively R _k =6.3mm and R ₀ =55.4mm, as shown in FIG. 1 . The blade has a thickness. Taking the blade thickness t=1mm, the outer diameter of the blade arc R _k '=7.3mm. The width between the impeller blades (channel width) t=(0.7～1.2)R _k , and the small impeller blades take t=1.1R _k , then the number of blades z=π*D ₁ /t=42.

The traditional impeller blade inlet adopts an acute angle inlet, which will cause the air flow to enter the flow channel, and the acute angle cut will make the air flow violently separate, which will cause noise and energy loss. The improved blade of the utility model replaces the acute angle cut with the airfoil arc, so that the process of the airflow entering the blade flow channel is smooth, the violent differentiation of the airflow is reduced, and the noise and energy loss are reduced.

More preferably, in order to prevent the gas from the impeller from flowing back to the interior of the impeller from the gap under the rear disk of the impeller, in this embodiment, the rear disk is designed to be tapered, forming an angle of 8-12° with the conventional disk surface, and the preferred angle of this embodiment is 10°. , as shown in Figure 3, the shaded part is the cutout part. After the removal, the clearance of the impeller site gradually decreases by 10° from the center of the impeller to the edge.

In the embodiment of the utility model, the airfoil arc is used to replace the acute angle at the inlet of the impeller blade, and the twisted blade, the backward blade and the impeller chassis can be effectively increased by 1% to 3%, and the flow rate of the exhaust fan can be reduced by 0.5dB to 3dB. noise. Compared with the original conventional blade, the improved blade has an increase of 8% to 10% in flow and a reduction of 2dB to 3dB in noise. The impeller exhaust fan of the utility model can effectively improve its overall performance.

Of course, the above-mentioned embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose thereof is to enable those who are familiar with the technology to understand the content of the present invention and implement accordingly, and cannot limit the protection scope of the present invention with this. All modifications made according to the spirit and essence of the main technical solutions of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. The impeller of the high-efficiency low-noise small-sized multi-wing centrifugal exhaust fan is characterized by comprising blades, wherein the front edge direction of each blade is twisted and tilted backwards along the rear edge direction, the twisting angle is 8-12 degrees, and the tilting angle is 2-6 degrees.

2. The impeller of a high efficiency low noise compact multiple wing centrifugal exhaust fan according to claim 1 wherein the inlet angle of the blades is in a circular arc configuration.

3. The impeller of a high efficiency low noise small multi-vane centrifugal exhaust fan as claimed in claim 2, wherein the angle of the inlet angle of the vane is in the range of 40 ° to 50 °.

4. The impeller of a high efficiency low noise compact multi-vane centrifugal exhaust fan as claimed in claim 3, wherein the angle of the outlet angle of the blades ranges from 165 ° to 175 °.

5. The impeller of a high efficiency low noise small size multi-blade centrifugal exhaust fan as claimed in claim 4, wherein the distance of the flow path between the blades is 6mm to 8 mm.

6. The impeller of the high-efficiency low-noise small-sized multi-wing centrifugal exhaust fan as claimed in claim 5, wherein the chassis at the root of the impeller is chamfered at an angle of 6-12 °.

7. The impeller of a high efficiency low noise compact multiple wing centrifugal exhaust fan according to claim 6 wherein the radius of the blade arc is:

wherein D is₂Is the outer diameter of the impeller, D₁Is the impeller inner diameter, β₂Angle of exit angle of impeller, β₁Angle of inlet angle of impeller, R₁Is the inner radius of the impeller, R₂Is the outer radius of the impeller.

8. The impeller of a high efficiency low noise small size multi-blade centrifugal exhaust fan as claimed in claim 7, wherein the radius of the arc of the center of the impeller is

9. The impeller of a high efficiency low noise small size multi-blade centrifugal exhaust fan as claimed in claim 7, wherein the upper half of the blade is twisted and tilted backward and the lower half of the blade is thickened and tilted backward.

10. A high efficiency, low noise, compact, multi-winged centrifugal exhaust fan comprising an impeller according to any one of claims 1 to 9.