Blade of centrifugal fan, impeller comprising same and centrifugal fan

Abstract

The utility model provides a blade of a centrifugal fan, an impeller comprising the blade and the centrifugal fan, the molded line of the blade comprises an inlet section and an outlet section, and the curvature of the inlet section is larger than that of the outlet section; the inlet arc-shaped angle is not greater than the outlet arc-shaped angle, and the inlet arc-shaped angle and the outlet arc-shaped angle are divided into a plurality of equal angles by connecting lines of a plurality of control points of the blades and the arc-shaped center; along the direction opposite to the airflow direction, the distances between the plurality of control points on the outlet section and the center of the arc are progressively increased in a second-order arithmetic progression, and / or the distances between the plurality of control points on the inlet section and the center of the arc are progressively decreased in a second-order arithmetic progression. According to the blade of the centrifugal fan, the impeller comprising the same and the centrifugal fan, the incoming flow direction can be better matched at the inlet section, so that more airflow can'flow in '; and blade channel vortexes in the blade channels can be effectively reduced at the outlet section, so that airflow flows out more quickly, the drainage effect is improved, noise is reduced, and the working efficiency and the working performance of the fan are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of fan, especially centrifugal fan's blade and including its impeller, centrifugal fan. BACKGROUND

[0002] Multi-wing centrifugal fan is the core power component of providing range hood air inlet capacity, and its aerodynamic performance determines the oil fume extractor suction capacity. Impeller is the main working component of multi-wing centrifugal fan, and its performance determines the fan air volume, wind pressure and noise. The blade profile of impeller often has great influence on the performance of impeller. At present, the blade of impeller mainly adopts single circular arc profile blade, and the main advantage is simple processing and high design maturity. However, since the gas has a large angle of attack when entering the blade channel when the impeller rotates, and the local turning angle of the blade is relatively large, it is easy to cause the existence of inter-blade vortex in most areas of the blade channel, which seriously affects the aerodynamic performance of the impeller.

[0003] Therefore, the technical personnel designs double circular arc profile blade, airfoil blade and other blade structures, which can reduce the inter-blade vortex to a certain extent. However, in the prior art, whether the blade is single circular arc profile blade or double circular arc profile blade or airfoil blade, the expansion trend of the circular arc curve is difficult to match the flow trend of the gas between the blade channels, the guiding effect is poor, it is difficult to effectively avoid the blade channel vortex, and the working efficiency and performance of the fan are affected. INVENTION CONTENTS

[0004] The utility model wants to solve the technical problem that the blade profile of the fan in the prior art has poor guiding effect, and provides a centrifugal fan blade and an impeller and a centrifugal fan comprising the same.

[0005] The utility model solves the above technical problem by the following technical scheme:

[0006] A centrifugal fan blade, the profile of the blade comprises an inlet section and an outlet section which are smoothly connected along the flow direction of the airflow, and the curvature of the inlet section is greater than that of the outlet section;

[0007] The inlet arc angle of the inlet section relative to the arc center is not greater than the outlet arc angle of the outlet section relative to the arc center, wherein the arc center is set as a point on the vertical bisector of the line connecting the two ends of the blade profile;

[0008] The profile of the blade comprises a plurality of control points on the inlet section and the outlet section, and the line connecting the plurality of control points and the arc center divides the inlet arc angle and the outlet arc angle into a plurality of equal angles;

[0009] The distance between the control points on the outlet section and the center of the arc increases in a second-order arithmetic progression in the direction opposite to the flow direction of the airflow, and / or the distance between the control points on the inlet section and the center of the arc decreases in a second-order arithmetic progression.

[0010] In the scheme, the blade of the centrifugal fan is designed by the above-mentioned setting curve, which can better match the flow direction at the inlet section, so that the airflow can flow in more; the outlet section can effectively reduce the blade passage vortex in the blade passage, so that the airflow flows out faster, thereby improving the flow guiding effect, reducing the noise, and improving the working efficiency and performance of the blade. The curvature of the inlet section is greater than that of the outlet section. On the one hand, the high curvature of the inlet section can better match the flow direction when the airflow enters, and can flow in smoothly; on the other hand, the curvature of the outlet section is small, and the resistance of the airflow in the blade passage is small, thereby avoiding the blade passage vortex, improving the flow guiding effect and the working efficiency of the blade. The design of the inlet arc angle being not greater than the outlet arc angle makes the outlet section have a longer arc curve, buffers the resistance of the airflow in the blade passage, and is beneficial to avoiding the blade passage vortex. The smooth transition curve formed by the above-mentioned control points based on the second-order arithmetic progression law effectively reduces the formation of vortex in the blade passage, improves the internal flow, and improves the performance of the fan.

[0011] Preferably, the angle between the inlet section and the tangent of the blade profile at the connection between the inlet section and the outlet section is an inlet inclination angle, the angle between the inlet section and the tangent of the airflow direction is a shock angle, and the difference between the inlet inclination angle and the shock angle is not greater than a set angle value.

[0012] In the scheme, by adjusting the curvature of the inlet section, the difference between the inlet inclination angle and the shock angle is not greater than a set angle value, that is, the difference between the inlet inclination angle and the shock angle is reduced, and the inclination angle of the inlet section can be matched with the flow direction to reduce the inlet resistance.

[0013] Preferably, the control points on the outlet section and / or the inlet section are connected as a logarithmic spiral.

[0014] In the scheme, compared with other curve structures, the connection line of the control points on the outlet section and / or the inlet section adopts a curve structure formed by a logarithmic spiral, which has the functions of collecting and guiding airflow, and is more beneficial to reducing the formation of blade passage vortex, improving the internal flow, and improving the performance of the fan.

[0015] Preferably, the distance between the end of the outlet section along the flow direction and the center of the arc is an initial distance, the distance between the first control point on the outlet section in the direction opposite to the flow direction and the center of the arc is a first distance, and the difference b between the first distance and the initial distance satisfies: ; wherein R and r are the outer diameter and inner diameter of the impeller formed by the plurality of blades in the centrifugal fan.

[0016] In this solution, each control point is obtained by using the difference b satisfying the above condition, and the profile drawn by using the control points is smooth, which is beneficial to reduce the formation of vortex in the blade channel and to make the flow smoother.

[0017] Preferably, the difference d of the second-order arithmetic sequence satisfies: ; wherein R and r are the outer diameter and inner diameter of the impeller formed by the plurality of blades in the centrifugal fan.

[0018] In this solution, the value d satisfying the above condition is used as the difference of the second-order arithmetic sequence increasing or decreasing, and the profile drawn by using the control points is smooth, which is beneficial to reduce the formation of vortex in the blade channel and to make the flow smoother.

[0019] Preferably, the outlet arc angle is twice the inlet arc angle.

[0020] In this solution, the above angle size relationship ensures that the profile of the outlet section is long enough, and the outlet section has enough space to buffer the resistance of the airflow in the blade channel, thereby improving the flow guiding effect.

[0021] An impeller, comprising a plurality of blades of the centrifugal fan as described above arranged in a ring.

[0022] In this solution, the impeller uses the blades designed as described above, which can better match the incoming flow direction at the inlet section, so that the airflow can flow in more; and can effectively reduce the blade channel vortex in the blade channel at the outlet section, so that the airflow can flow out faster, thereby improving the flow guiding effect, reducing noise, and improving the working efficiency and performance of the impeller.

[0023] Preferably, the inlet section is arranged such that the inclination direction of the inlet section relative to the tangent line is consistent with the airflow direction at the inlet section; wherein the tangent line is the tangent line of the blade profile at the connection between the inlet section and the outlet section.

[0024] In this solution, by adjusting the setting direction of the inlet section, the inclination direction of the inlet section relative to the tangent line is consistent with the airflow direction at the inlet section, thereby reducing the air inlet resistance.

[0025] Preferably, the plurality of blades are arranged at equal intervals in the circumferential direction, the curvatures of the inlet sections of all the blades are the same, and the curvatures of the outlet sections of all the blades are the same.

[0026] In the scheme, the several blades are equidistantly arranged in the circumference, the airflow pressure in the blade channel between the blades is uniform, which is beneficial to the airflow stability. The size of the interval between the blades is adjusted, the blade channel vortex is avoided. The curves of all the inlet sections are same, the curvatures of all the outlet sections are same, the shape structure is regular, the manufacturing difficulty is reduced, the airflow stability is improved, and the working performance of the impeller is improved.

[0027] A centrifugal fan comprises the impeller as described above.

[0028] In the scheme, the centrifugal fan adopts the above-mentioned impeller, the inlet section of each blade is better matched with the airflow direction, the airflow can flow in more, the blade channel vortex in the outlet section is effectively reduced, the airflow can flow out faster, the airflow guiding effect is improved, the noise is reduced, and the working efficiency and working performance of the fan are improved.

[0029] The positive progress effect of the centrifugal fan lies in that: the blade of the centrifugal fan and the impeller and the centrifugal fan comprising the same can better match the airflow direction at the inlet section of each blade, so that the airflow can flow in more; the blade channel vortex in the outlet section can be effectively reduced, so that the airflow can flow out faster, the airflow guiding effect is improved, the noise is reduced, and the working efficiency and working performance of the fan are improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 1 is a three-dimensional structure schematic view of the impeller of the centrifugal fan according to the present application.

[0031] Figure 2 FIG. 2 is a side structure schematic view of the impeller of the centrifugal fan according to the present application.

[0032] Figure 3 FIG. 3 is a profile structure schematic view of the blade of the centrifugal fan according to the present application. Figure 2 FIG. 4 is a sectional view along the A-A direction.

[0033] Figure 4 FIG. 5 is a schematic view of the relationship between the blade profile and the gas flow direction of the centrifugal fan according to the present application.

[0034] Figure 5

[0035] BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0036] Impeller 1

[0037] Blade 2

[0038] Inlet section 21

[0039] Outlet section 22

[0040] Tangent 3​

[0041] Airflow direction B Detailed Implementation

[0042] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0043] Example 1

[0044] This embodiment provides a centrifugal fan blade 2. An impeller 1, composed of several blades 2 arranged in a ring, is installed inside the centrifugal fan. During operation, airflow enters the blade passage between the blades 2 from the inner ring of the impeller 1. Then, under the centrifugal motion of the impeller 1, the airflow is guided to flow out from the outer ring of the impeller 1. The outer side of the impeller 1 is the fan casing (not shown in the figure). After the guided airflow flows out, it flows in the air passage between the impeller 1 and the casing. Under the action of centrifugal force, the airflow is discharged from the casing outlet along the air passage, thereby realizing the exhaust function.

[0045] like Figures 1-5 As shown, the profile of blade 2 includes a smooth transition between an inlet section 21 and an outlet section 22 along the airflow direction B. The curvature of the inlet section 21 is greater than that of the outlet section 22, meaning that the curve radius of the inlet section 21 is small and the curvature is large; while the curve radius of the outlet section 22 is large and the curvature is small, making it relatively smooth.

[0046] The inlet arc angle of the inlet segment 21 relative to the arc center is not greater than the outlet arc angle of the outlet segment 22 relative to the arc center, wherein the arc center is set as a point on the perpendicular bisector of the line connecting the two ends of the blade profile 2.

[0047] The blade 2 profile includes several control points on the inlet section 21 and the outlet section 22. The lines connecting these control points to the center of the arc divide the inlet and outlet arc angles into several equally spaced angles. Along the flow direction B opposite to the airflow, the distances between the control points on the outlet section 22 and the center of the arc increase in a second-order arithmetic progression, and / or, the distances between the control points on the inlet section 21 and the center of the arc decrease in a second-order arithmetic progression.

[0048] Specifically, such as Figure 4 As shown, in this embodiment, the profile of blade 2 includes seven control points, including the inlet endpoint B, the outlet endpoint A, and intermediate control points E, F, C, D and G between point A and point B. The inlet segment 21 is the curve segment from point D to point B, and the outlet segment 22 is the curve segment from point A to point D.

[0049] In determining the position of each control point, first, the up and down position relationship of each control point on the profile line is determined, that is, whether the control point is more on the outside or closer to the inside. Specifically, based on the determined positions of the entry end point B and the exit end point A, a perpendicular bisector of the AB connecting line is drawn, and a fixed point O is taken on the perpendicular bisector, which is set as the center of the arc of the profile line of the blade 2. The seven control points divide the overall arc angle ∠AOB of the profile line of the blade 2 into six equal parts. In this way, the up and down positions of the intermediate control points on the profile line are determined by the equal angle size relationship. According to the angle equalization, the entry arc angle is ∠BOD, and the exit arc angle is ∠AOD, which includes four equal angle parts and two equal angle parts, respectively.

[0050] Then, the left and right position relationship of each control point needs to be determined, which is embodied in the curvature of the curve formed by the control points. Specifically, the control points on the exit section 22 are determined according to the rule of increasing in the second-order arithmetic sequence. Since the center O of the arc is a point on the perpendicular bisector of the AB connecting line, the distances from the O point to the A point and the B point are equal, that is, OA=OB, and the length between OA and OB is a1; along the flow direction opposite to the airflow B, the next control point of the A point is E, and the length of OE is a2, that is, a2=a1+b, b is a parameter for length adjustment based on the principle of the second-order arithmetic sequence; let d be the difference of the second-order arithmetic sequence, then the distance from the O point to the third point, that is, OF, is a1+2b+d, the distance between OC is a1+3b+3d, and the distance between OD is a1+4b+6d. After determining the lengths of these control points, the control points are connected and drawn into a smooth profile line, forming the profile line of the exit section 22 with smaller curvature. On the entry section 21, the control points are determined according to the rule of decreasing in the second-order arithmetic sequence. Based on the lengths of OD and OB calculated in the above manner, and according to the decreasing rule of the second-order arithmetic sequence, the length of OG is a1+2b; then the D point, the G point and the B point on the entry section 21 are connected and drawn into a smooth profile line, forming the profile line of the entry section 21 with larger curvature.

[0051] The blade 2 of the centrifugal fan is easy to better match the flow direction at the inlet section 21, so that the airflow can flow in more; the blade channel vortex in the blade channel can be effectively reduced at the outlet section 22, so that the airflow flows out faster, thereby improving the flow guiding effect, reducing the noise, and improving the working efficiency and working performance of the blade 2. The curvature of the inlet section 21 is greater than the curvature of the outlet section 22. On the one hand, the high curvature of the inlet section 21 makes the inlet section 21 better match the flow direction when the airflow enters, and can smoothly flow in. On the other hand, the curvature of the outlet section 22 is small, and the airflow has small resistance in the blade channel, thereby avoiding the blade channel vortex, improving the flow guiding effect, and improving the working efficiency of the blade 2. The design that the inlet arc angle is not greater than the outlet arc angle makes the outlet section 22 have a long arc curve, buffers the resistance of the airflow in the blade channel, and is beneficial to avoiding the blade channel vortex. The smooth transition curve formed by the plurality of control points based on the second-order arithmetic progression rule of the outlet section 22 and / or the inlet section 21 effectively reduces the formation of the vortex in the blade channel, improves the internal flow, and improves the performance of the fan.

[0052] In other embodiments, based on the above setting principle, in order to better construct a suitable curvature profile to avoid the blade channel vortex and improve the working performance of the blade 2, the number of control points can be adjusted as needed, for example, more control points can be used to make the curve connected and drawn smoother.

[0053] As shown in FIG. 1, the blade 2 of the centrifugal fan has an inlet section 21 and an outlet section 22. The inlet section 21 is connected to the outlet section 22, and the blade 2 has a smooth transition curve at the connection between the inlet section 21 and the outlet section 22. The blade 2 is provided with a plurality of control points based on the second-order arithmetic progression rule. The plurality of control points are connected and drawn to form the smooth transition curve of the blade 2. Figure 5 As shown in FIG. 1, the blade 2 of the centrifugal fan has an inlet section 21 and an outlet section 22. The inlet section 21 is connected to the outlet section 22, and the blade 2 has a smooth transition curve at the connection between the inlet section 21 and the outlet section 22. The blade 2 is provided with a plurality of control points based on the second-order arithmetic progression rule. The plurality of control points are connected and drawn to form the smooth transition curve of the blade 2.

[0054] In the present embodiment, the plurality of control points on the outlet section 22 are drawn into the profile based on the principle of logarithmic spiral, that is, the profile is a logarithmic spiral based on the parameter equation of the logarithmic spiral. The parameter equation of the logarithmic spiral is an equation in the prior art, which is not described herein. The plurality of control points on the inlet section 21 are drawn into the profile based on a cubic equation, which is also an equation in the prior art, which is not described herein. In other embodiments, the plurality of control points on the inlet section 21 can also be drawn into the profile based on the principle of logarithmic spiral.

[0055] Compared with other curve structures, the curve structure formed by connecting lines of several control points on the outlet section 22 and / or the inlet section 21 adopts a logarithmic spiral line, which has both gas collecting and flow guiding effects, is more conducive to reducing the formation of blade channel vortices, improving internal flow, and improving the performance of the fan.

[0056] In the formula, the distance between the end of the outlet section 22 along the flow direction B and the center of the arc is the initial distance, that is, the length a1 of the connecting line OA is the initial distance; the distance between the first control point of the outlet section 22 along the opposite direction of the flow direction B and the center of the arc is the first distance, that is, the length a2 of the connecting line OE is the first distance, and the difference b between the first distance and the initial distance satisfies the condition that b < (R-r) / 2. In the formula, R and r are the outer diameter and the inner diameter of the impeller 1 formed by the plurality of blades 2 in the centrifugal fan. The difference b satisfying the above condition is used to obtain each control point, and the profile line drawn based on the control point is smooth, which is conducive to reducing the formation of vortices in the blade channel and improving the flow.

[0057] Further, the difference d of the second-order arithmetic sequence also satisfies the condition that d < (R-r) / 2. In the formula, R and r are also the outer diameter and the inner diameter of the impeller 1 formed by the plurality of blades 2 in the centrifugal fan. The value d satisfying the above condition is used as the difference for the second-order arithmetic sequence to increase or decrease, and the profile line drawn based on the control point is smooth, which is conducive to reducing the formation of vortices in the blade channel and improving the flow.

[0058] By adjusting the values of b and d, the arc shape of the profile line can be adjusted. If b and d are both zero, the profile line obtained by the above formula represents a single circular arc-shaped blade 2. The profile line obtained by adjusting the values of b and d can also be used to approximate the shape of a double circular arc blade 2. Therefore, under the condition that b and d satisfy the above range, by adjusting the values of b and d, more selective blade 2 profile lines can be obtained, and a profile line structure that can effectively avoid blade channel vortices can be obtained more easily.

[0059] As described above, in the embodiment, the outlet arc angle ∠AOD is preferably twice the inlet arc angle ∠BOD. In other embodiments, the angle relationship between the outlet arc angle ∠AOD and the inlet arc angle ∠BOD can be adjusted according to the effect. Generally, the outlet arc angle ∠AOD = N*inlet arc angle ∠BOD, N≥1, but it is preferred to use the twice size relationship of the embodiment. By using such an angle size relationship, it is ensured that the profile line of the outlet section 22 is long enough, and the outlet section 22 has enough space to buffer the resistance of the airflow in the blade channel, thereby improving the flow guiding effect.

[0060] Embodiment 2

[0061] The embodiment provides a kind of impeller 1, which includes a plurality of blades 2 as described in embodiment 1 arranged in a ring, and constitutes a ring structure as a whole.The impeller 1 is easy to better match the flow direction of incoming flow by using the above-mentioned designed blade 2, so that the airflow can be more "flow in";In the outlet section 22, the blade channel vortex in the blade channel can be effectively reduced, so that the airflow is faster "flow out", thereby improving the flow effect, reducing noise, improving the working efficiency and working performance of the impeller 1.

[0062] Wherein, the inlet section 21 is arranged to be consistent with the air flow direction of the inlet section 21 relative to the inclination direction of tangent 3, that is, when the blade 2 is arranged in the volute of the fan, the setting direction of the blade 2 can be adjusted, so that the setting direction of the inlet section 21 is consistent with the air flow direction of the inlet section 21 relative to the inclination direction of tangent 3, and the air resistance is reduced.

[0063] Wherein, a plurality of blades 2 are arranged at equal intervals in the circumferential direction, the curvatures of the inlet sections 21 of all blades 2 are the same, and the curvatures of the outlet sections 22 of all blades 2 are the same.A plurality of blades 2 are arranged at equal intervals in the circumferential direction, and the airflow pressure in the blade channel between each blade 2 is uniform, which is conducive to stable airflow.Wherein, the spacing between the blades 2 is adjusted so that the spacing between the blades 2 is neither too small to affect the flow effect nor too large to easily produce blade channel vortex;Therefore, reasonable spacing between the blades 2 can avoid the generation of blade channel vortex, and the gas flow is more smooth.All the inlet sections 21 have the same curvature, and all the outlet sections 22 have the same curvature, so that the shape structure is regular, the manufacturing difficulty is reduced, the stability of the airflow is improved, and the working performance of the impeller 1 is improved.

[0064] Embodiment 3

[0065] The embodiment provides a centrifugal fan, which comprises the impeller 1 as described in embodiment 2.The centrifugal fan is easy to better match the flow direction of incoming flow by using the above-mentioned impeller 1, so that the airflow can be more "flow in";In the outlet section 22, the blade channel vortex in the blade channel can be effectively reduced, so that the airflow is faster "flow out", thereby improving the flow effect, reducing noise, improving the working efficiency and working performance of the fan.

[0066] Although the specific embodiments of the present application are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A blade for a centrifugal fan, the profile of the blade comprising a smoothly transitioning inlet section and an outlet section in the direction of flow of the airflow, characterised in that, The curvature of the inlet section is greater than the curvature of the outlet section. The inlet arc angle of the inlet section relative to the arc center is not greater than the outlet arc angle of the outlet section relative to the arc center, wherein the arc center is arranged as a point on the vertical bisector of the line connecting the two ends of the blade profile. The profile of the blade includes a plurality of control points on the inlet section and the outlet section, and the line connecting the control points and the arc center divides the inlet arc angle and the outlet arc angle into a plurality of equal angles. In the opposite direction of the flow of the air flow, the distance between the control points on the outlet section and the arc center increases in a second-order arithmetic sequence, and / or the distance between the control points on the inlet section and the arc center decreases in a second-order arithmetic sequence.

2. The blade of a centrifugal fan as set forth in claim 1, wherein The angle between the inlet section and the tangent of the blade profile at the connection between the inlet section and the outlet section is an inlet inclination angle, the angle between the air inlet direction of the inlet section and the tangent is a shock angle, and the difference between the inlet inclination angle and the shock angle is not greater than a set angle value.

3. The blade of a centrifugal fan as set forth in claim 1, wherein The control points on the outlet section and / or the inlet section are connected as a logarithmic spiral.

4. The blade of a centrifugal fan as set forth in claim 1, wherein The distance between the end of the outlet section along the flow direction and the center of the arc is an initial distance, the distance between the first control point along the opposite direction of the flow direction and the center of the arc is a first distance, and the difference b between the first distance and the initial distance satisfies: ; Wherein R and r are the outer diameter and inner diameter of the impeller formed by a plurality of blades in the centrifugal fan.

5. The blade of a centrifugal fan as set forth in claim 1, wherein The difference value d of the second-order arithmetic sequence satisfies: ; Wherein R and r are the outer diameter and inner diameter of the impeller formed by a plurality of blades in the centrifugal fan.

6. The blade of a centrifugal fan as set forth in claim 1, wherein The outlet arc angle is twice the inlet arc angle.

7. An impeller, characterized by The impeller includes a plurality of blades of the centrifugal fan according to any one of claims 1-6 arranged in a ring.

8. The impeller of claim 7, wherein The inlet section is arranged such that the inclination direction of the inlet section relative to the tangent is consistent with the air inlet direction of the inlet section, and the tangent is the tangent of the blade profile at the connection between the inlet section and the outlet section.

9. The impeller of claim 7 wherein, The plurality of blades are arranged at equal intervals in the circumferential direction, the curvatures of the inlet sections of all the blades are the same, and the curvatures of the outlet sections of all the blades are the same.

10. A centrifugal fan characterized by The centrifugal fan includes the impeller according to any one of claims 7-9.

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