Air inlet rectifying grille and backward centrifugal fan applying same

Abstract

The application discloses an air inlet rectifying grid and a backward centrifugal fan applying the same, and belongs to the technical field of centrifugal fans. The air inlet rectifying grid comprises a plurality of ring grids and a plurality of rectifying strips. The rectifying strips are distributed radially around the center of the ring grid. The included angle between the rectifying strip and the air inlet direction is A, and 0° < A ≤ 25°. The rectifying strip exerts a rotating effect on the air inlet, reduces the pushing force of the air, and thus reduces the generation of noise. The air inlet rectifying grid utilizes the overflow air flow of the fan to prolong the air acceleration time, reduces the air reaction force, and reduces the generation of vibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of centrifugal fan, in particular to an air inlet rectifying grid and a backward centrifugal fan using the same. BACKGROUND

[0002] The backward centrifugal fan is widely used in production and life due to high efficiency of driving air flow and wide stable working area. The turbulence of the air flow in the aerodynamic area of the blade of the backward centrifugal fan is relatively large when the air is inhaled, which produces loud noise, affects the use of customers, and reduces the efficiency of air intake. Under the premise of not changing the air intake ring and the impeller, a rectifying grid needs to be added to the air intake opening of the air intake ring to rectify the air flow entering the impeller. The existing rectifying grid can reduce the noise of air intake, but it additionally increases the resistance of air intake, reduces the air volume, air pressure and blowing efficiency of the fan.

[0003] The patent with publication number CN209944584U discloses an air inlet grid and an air conditioner outdoor unit. The air inlet grid is located on the air inlet side of the fan and includes circumferential guide vanes and radial guide vanes. The circumferential guide vane located on the inner side of the two adjacent circumferential guide vanes is located upstream of the other circumferential guide vane. The two adjacent circumferential guide vanes are connected by the radial guide vane. In the axial direction, the thickness of the air inlet grid is H, and the radius of the outer peripheral wall of the air inlet grid is R, wherein the value of R / H is in the range of 1.5-3. Thus, the air flow is rectified by the circumferential guide vanes and the radial guide vanes before entering the fan, thereby achieving the purpose of reducing the noise of air intake. However, the air inlet grid reduces the air volume of air intake and increases the load of the fan wheel while rectifying, resulting in a lower blowing efficiency of the fan under the same power. SUMMARY

[0004] The purpose of the present application is to provide an air inlet rectifying grid that solves the problem of low blowing efficiency caused by high resistance during air intake rectification of the existing air inlet grid.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0006] An air inlet rectifying grid includes a plurality of ring grids and a plurality of rectifying strips. The plurality of rectifying strips are distributed radially around the center of the ring grid. The included angle between the rectifying strip and the air inlet direction is A, and 0°<A≤25°. The rectifying strip exerts a rotating effect on the air inlet, thereby reducing the driving force of the air and reducing the generation of noise. The air inlet rectifying grid uses the overflow air flow of the fan to prolong the acceleration time of the air, thereby reducing the reaction force of the air and reducing the generation of vibration.

[0007] Further, the first ring gate, the second ring gate and the third ring gate are sequentially arranged on the rectifier strip from inside to outside, and the rectifier strip is divided into multiple segments, the rectifier strip comprises a first rectifier segment, a second rectifier segment and a third rectifier segment, the first rectifier segment occupies a first rectifier area, the second rectifier segment occupies a second rectifier area, and the third rectifier segment occupies a third rectifier area, the air intake pre-rotation speed of the air is adjusted by dividing the rectifier area, the thrust of the wind wheel is matched, the generation of turbulence is reduced, and the consumption of internal airflow collision is reduced.

[0008] Further, the area of the second rectifier area is greater than that of the third rectifier area, and the area of the third rectifier area is greater than that of the first rectifier area, and the second rectifier area accounts for 65% to 75% of the total rectifier area.

[0009] Preferably, the included angle between the second rectifier segment and the air inlet direction is greater than 5°, sufficient pre-rotation force is applied, and the effect of reducing noise is achieved.

[0010] Preferably, the number of the first rectifier segment is less than or equal to the number of the second rectifier segment, and the number of the third rectifier segment is greater than or equal to the number of the second rectifier segment, the rectifier segments are uniformly arranged according to the range of rectification, and the stability of the rectification effect is ensured.

[0011] Preferably, as viewed in the air inlet direction, the height difference H of the two ends of the rectifier strip is positively correlated with the included angle A between the rectifier strip and the air inlet direction, and the best air outlet performance can be obtained by adjusting the included angle A and the height difference H.

[0012] Preferably, the height difference H of the rectifier strip is in the range of 40-75mm.

[0013] Preferably, the multiple ring gates are inclined to the air inlet direction, so that the air inlet is gathered to the center of the ring gate, the air inlet efficiency is improved, and the noise is reduced.

[0014] The second purpose of the present application is to provide a backward centrifugal fan, which solves the problems of large air inlet resistance and large noise of the existing centrifugal fan.

[0015] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0016] A backward centrifugal fan comprises an air inlet rectification grid, an air inlet ring and an impeller, the air inlet ring is coaxially arranged with the impeller, one end of the air inlet rectification grid is in contact with the air inlet ring, the air entering the impeller is pre-rotated by the rectification and then focused by the air inlet ring, the air inlet amount of the impeller is improved, and the noise is reduced.

[0017] Preferably, the inner circle diameter D1 of the air inlet rectification grid is 70-85% of the inner diameter D2 of the air inlet circle.

[0018] The present application has the following advantages:

[0019] (1) The air inlet rectification grid is provided with a plurality of ring grids and a plurality of rectification strips. The plurality of ring grids are arranged at intervals from the center to the outside, dividing the rectification strips into multiple sections. The rectification strips are arranged radially and at an angle to the direction of the air inlet. The rectification strips impart a rotating effect on the air inlet, guiding the direction of the air inlet to be the same as the rotating direction of the impeller, rectifying the air inlet, reducing the resistance and noise of the air inlet, and improving the comfort of using the fan.

[0020] (2) The rectification area of the air inlet rectification grid is divided into a plurality of areas distributed from the center to the outside. The inclination angle of the rectification strips in each area is different, and the number of rectification strips is also different. The inclination angle of the rectification strips in the middle area of the air inlet area is large, and the number of rectification strips in the outermost area is large. According to the size of the air inlet in each area, the inclination angle and number of rectification strips can better impart a pre-rotation effect on the air inlet, improve the consistency of the moving direction of the air inlet and the rotating direction of the impeller, thereby improving the air inlet and reducing the noise of the air inlet.

[0021] (3) The center of the ring grid of the air inlet rectification grid is inclined, which has the effect of gathering the air inlet to the center. It is the same as the direction of the air inlet of the centrifugal fan, which can improve the efficiency of the air inlet.

[0022] (4) The backward centrifugal fan is provided with an air inlet rectification grid. The air inlet rectification grid is installed on the air inlet circle. The air inlet circle can gather the air inlet to the center of the impeller, reduce the resistance of the air inlet of the impeller, and thus improve the efficiency of the air inlet. The air inlet rectification grid can guide the air in the air inlet area of the air inlet circle. By expanding the guiding ability of the air and imparting a pre-rotation effect on the air inlet, the resistance of the air rotating driven by the impeller is reduced, and the noise and power loss of the fan during operation are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A perspective view of the backward centrifugal fan provided by the present application is provided.

[0024] Figure 2 A front view of the air inlet rectification grid provided by the present application is provided.

[0025] Figure 3 A top view of the air inlet rectification grid provided by the present application is provided.

[0026] Figure 4 A front view of the air inlet rectification grid provided by the present application is provided.

[0027] Figure 5 A side view of the air inlet rectification grid provided by the present application is provided.

[0028] Reference numerals:

[0029] 1. Inlet air rectifying grille; 11. Ring grille; 111. First ring grille; 112. Second ring grille; 113. Third ring grille; 12. Rectifying strip; 121. First rectifying section; 122. Second rectifying section; 123 Third rectifying section; 2. Inlet air ring; 3. Impeller; 4. Motor; 5. Air inlet; A. First rectifying area; B. Second rectifying area; C. Third rectifying area. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0031] Embodiment 1

[0032] As Figures 1-3 shown, the present invention discloses an inlet air rectifying grille 1, which includes a plurality of ring grilles 11 and a plurality of rectifying strips 12. The plurality of rectifying strips 12 are radially distributed around the center of the ring grille 11. The included angle between the rectifying strip 12 and the air inlet direction is A, 0° < A ≤ 25°. The air inlet direction is parallel to the axis of the ring grille 11. The plurality of ring grilles 11 divide the rectifying area into a plurality of annular regions. Each annular region is divided into multiple blocks by the rectifying strip 12. The air in the region is divided and guided by the rectifying strip 12 under the action of suction. The rectifying strip 12 is inclined with respect to the air inlet direction, so that the incoming air is applied with a rotating effect around the center of the inlet air rectifying grille 1. By applying a rotating effect to the air, the force for accelerating the air can be reduced, thereby reducing the noise caused by the reaction force. The force for applying the pre-rotation effect comes from the fan itself, which improves the overall air outlet efficiency. As the angle A of the rectifying strip 12 increases, the influence of the rectifying strip 12 on the air blowing performance of the fan first increases and then weakens. After exceeding a certain range, the resistance of the rectifying strip 12 increases, which will cause the air blowing performance of the fan to decline.

[0033] Among them, the bottom end of the rectifying strip 12 is open to reduce the intake resistance. The top end of the rectifying strip 12 is closed by the ring grille 11, separating the central part of the fan from the rectifying area to prevent the generation of turbulent flow.

[0034] Further, the air inlet rectification grid further comprises a first ring grid 111, a second ring grid 112 and a third ring grid 113, which are sequentially arranged from inside to outside on the rectification strip 12, and divide the rectification strip 12 into multiple sections, the rectification strip 12 comprises a first rectification section 121, a second rectification section 122 and a third rectification section 123, the first rectification section 121 occupies a first rectification area A, the second rectification section 122 occupies a second rectification area B, and the third rectification section 123 occupies a third rectification area C, after the air fan inhales air, the acceleration of the air is different, the rectification area is divided according to the distance from the center of the centrifugal fan, so as to reduce internal turbulence and improve rectification efficiency.

[0035] Further, the area of the second rectification area B is greater than that of the third rectification area C, the area of the third rectification area C is greater than that of the first rectification area A, the second rectification area B accounts for 65% to 75% of the entire rectification area, the first rectification area A accounts for 10% to 15% of the entire rectification area, and the third rectification area C accounts for 15% to 20% of the entire rectification area.

[0036] Preferably, the angle between the second rectification section 122 and the air inlet direction is greater than 5°, the second rectification section 122 plays a major role in the entire rectification area, and the angle of the second rectification section 122 needs to be matched according to the speed and diameter of the impeller 3, so that the air inlet effect is better and the noise is smaller.

[0037] Further, the number of the first rectification section 121 is less than or equal to the number of the second rectification section 122, and the number of the third rectification section 123 is greater than or equal to the number of the second rectification section 122, and the air flow is guided according to the air inlet area.

[0038] Preferably, along the air inlet direction, the height difference H of the two ends of the rectification strip 12 is positively correlated with the angle A between the rectification strip 12 and the air inlet direction, as the inclination angle A increases, the height difference of the rectification grid also increases, and the rotation of the fan blade is smaller, and the rotation of the fan blade has an optimal interval, when the angle A of the rectification strip 12 reaches the maximum, the height difference H of the two ends of the rectification grid needs to be adjusted to ensure that the air blowing performance of the fan remains efficient.

[0039] Preferably, the height difference H of the rectification strip 1 is in the range of 40-75mm, and the cross section of the rectification strip 1 is streamline-shaped, so that the speed of the air after rectification is different, which has the same effect as the air pushing effect of the impeller 3, thereby reducing the burden of the impeller 3 and reducing noise and vibration.

[0040] Preferably, the multiple ring grids 11 are inclined to the air inlet direction, so that the air inlet is gathered to the center of the ring grid 11, which plays a role in preliminary flow concentration and air gathering.

[0041] Example two

[0042] As Figures 4-5 The application also discloses a backward centrifugal fan, which comprises an air inlet rectifying grid 1, an air inlet ring 2 and an impeller 3, the air inlet ring 2 is coaxially arranged with the impeller 3, one end of the air inlet rectifying grid 1 is in contact with the air inlet ring 2, the air inlet rectifying grid 1 is used for exerting a pre-rotation effect on air to be sucked in, and the air inlet ring 2 is used for expanding the air inlet range of the impeller 3 and gathering air entering the impeller 3, thereby improving the air inlet flow and the stability of the air inlet.

[0043] Preferably, the inner ring diameter D1 of the air inlet rectifying grid is 70%-85% of the inner diameter D2 of the air inlet ring 2, so as to exert a pre-rotation effect on a proper amount of air, too much air to be driven will reduce the rectifying effect, and too little air will not play a role in reducing noise.

[0044] The working process of the backward centrifugal fan is as follows:

[0045] Air enters the impeller 3 from the air inlet 5, and the air is sucked into the impeller 3 and passes through the air inlet rectifying grid 1 and the air inlet ring 2, the air in a certain range of the air inlet 5 is subjected to the suction effect of the impeller 3 to generate flow, at this time, the flow speed of the air is relatively slow, after the air passes through the rectifying strip 12, the air is subjected to an action force in the same direction as the rotation direction of the impeller 3 by the obliquely arranged rectifying strip 12, and the air is subjected to a stronger pre-rotation effect in the direction of the center of the fan, so that the air has a certain speed before being pushed by the impeller 3, the acceleration time of the air is prolonged by fully utilizing the pushing effect of the impeller 3, the air is focused to the center of the fan under the guidance of the air inlet ring 2 after being subjected to the pre-rotation effect of the air inlet rectifying grid 1, the air inlet range is expanded by the air inlet ring 2, the air inlet flow is improved, and finally the air is driven by the impeller 3 and discharged outward.

[0046] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present application should also fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in the present specification, these terms are only for convenience of description and do not constitute any limitation on the present application.

Claims

1. An air inlet rectifier grille, characterized by: The air inlet rectification grid comprises a plurality of ring grids (11) and a plurality of rectification strips (12), the plurality of rectification strips (12) are distributed radially around the center of the ring grid (11), and an included angle between the rectification strip (12) and an air inlet direction is A, 0°<A≤25°. The air inlet rectification grid further comprises a first ring grid (111), a second ring grid (112) and a third ring grid (113), the first ring grid (111), the second ring grid (112) and the third ring grid (113) are sequentially arranged from inside to outside on the rectification strip (12), and the rectification strip (12) is divided into a plurality of sections, the rectification strip (12) comprises a first rectification section (121), a second rectification section (122) and a third rectification section (123), a space occupied by the first rectification section (121) is a first rectification area (A), a space occupied by the second rectification section (122) is a second rectification area (B), and a space occupied by the third rectification section (123) is a third rectification area (C). An area of the second rectification area (B) is greater than that of the third rectification area (C), an area of the third rectification area (C) is greater than that of the first rectification area (A), and the second rectification area (B) accounts for 65% to 75% of the entire rectification area. When viewed along an axis of the ring grid (11), a height difference H of the rectification strip (12) at two ends is positively correlated with the included angle A between the rectification strip (12) and the air inlet direction, and the height difference H of the rectification grid at the two ends is greater as the included angle A increases. The height difference H of the rectification strip (12) is 40-75 mm, and a cross section of the rectification strip (12) is streamline-shaped.

2. The air inlet rectification grid according to claim 1, wherein: An included angle between the second rectification section (122) and the air inlet direction is greater than 5°.

3. The air inlet rectification grid according to claim 2, wherein: A number of the first rectification sections (121) is equal to that of the second rectification sections (122), and a number of the third rectification sections (123) is equal to that of the second rectification sections (122).

4. The air inlet rectification grid according to any one of claims 1-3, wherein: The plurality of ring grids (11) are inclined to the air inlet direction, so that the air inlet is gathered to the center of the ring grid (11).

5. A backward centrifugal fan characterized by: The air inlet rectification grid, the air inlet ring (2) and the impeller (3) according to any one of claims 1-4, the air inlet ring (2) and the impeller (3) are coaxially arranged, and one end of the air inlet rectification grid is in contact with the air inlet ring (2).

6. The backward centrifugal fan according to claim 5, wherein: An inner circle diameter D1 of the air inlet rectification grid is 70%-85% of an inner diameter D2 of the air inlet ring (2).

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