Axial flow fan and range hood comprising same

Abstract

The utility model relates to the field of axial flow fans, and discloses an axial flow fan and a range hood comprising the axial flow fan, the axial flow fan comprises a shell, a rotating shaft, a multi-stage blade assembly, a mounting part and a suspension support plate, the mounting part and the suspension support plate are correspondingly arranged, the mounting part is rotatably connected to the end part of the rotating shaft, and the suspension support plate, the mounting part and the shell are fixedly connected and located at the upstream or the downstream of the blade assembly. The thickness of the suspension supporting plate is gradually increased in the first direction to form a front portion and then gradually decreased to form a rear portion, the absolute value of the included angle between the contour tangent line of at least the outer supporting portion of the front portion and the first direction is unchanged or gradually decreased, and a natural draft angle can be formed. The absolute value of the included angle between the contour tangent line of at least the outer branch part of the rear part on the equal-radius surface and the first direction is unchanged or gradually increased, and a natural draft angle can be formed. Through the shape setting of the suspension support plate, the suspension support plate is convenient to process, and the obstruction to the fluid flow can be reduced.

Description

Technical Field

[0001] This utility model relates to the field of axial flow fans, and in particular to a multi-stage axial flow fan. Background Technology

[0002] In axial flow fans, the shaft is located inside the casing and needs to be supported. In a typical single-stage axial flow fan, the shaft is mounted on the stator blades. However, in a multi-stage axial flow fan, if the shaft is mounted on the upstream or downstream stator blades, it will be difficult to cast and demold the stator blades integrally with the casing, making manufacturing difficult. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the defects of the difficulty in manufacturing multi-stage axial flow fans in the prior art, and to provide an axial flow fan and a range hood including the same.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] An axial flow fan, comprising:

[0006] case;

[0007] The rotating shaft is disposed within the housing;

[0008] At least two stages of blade assemblies are arranged in the blade flow channel, sequentially along the axial direction of the rotating shaft;

[0009] The axial flow fan also includes at least one mounting component and at least one suspension support plate. The mounting component is disposed on and rotatably connected to the axial end of the rotating shaft. The suspension support plate is fixedly connected to the housing and the corresponding mounting component. Each suspension support plate is located upstream or downstream of the blade assembly.

[0010] The thickness of the suspension support plate gradually increases along the axial direction towards the outlet of the axial flow fan to form a front part and then gradually decreases to form a rear part. The suspension support plate has at least an outer support part with a radius greater than or equal to the minimum radius of the corresponding blade flow channel end. In the front part, the absolute value of the angle between the tangent of the windward and leeward sides of the outer support part on the plane of equal radius and the first direction remains unchanged or gradually decreases. In the rear part, the absolute value of the angle between the tangent of the windward and leeward sides of the outer support part on the plane of equal radius and the first direction remains unchanged or gradually increases.

[0011] In this solution, in an axial flow fan with multi-stage blade assemblies, mounting components and suspension plates are installed to install the rotating shaft, avoiding interference with the processing and manufacturing of other components in the axial flow fan and improving the ease of manufacturing the axial flow fan.

[0012] By setting the thickness of the front portion of the suspension support plate to gradually increase along the first direction, and ensuring that the absolute value of the angle between the tangent of the outer support portion of the front portion on the surface of equal radius and the first direction remains constant or gradually decreases, a natural draft angle is formed, facilitating demolding during casting manufacturing. Similarly, the thickness of the rear portion of the suspension support plate is set to gradually decrease along the first direction, and the absolute value of the angle between the tangent of the outer support portion of the rear portion on the surface of equal radius and the first direction remains constant or gradually increases, forming a natural draft angle for easy demolding during casting manufacturing. Furthermore, the radius of the outer support portion of the suspension support plate is greater than or equal to the minimum radius of the corresponding blade flow channel end. The outer support portion guides the fluid flow towards or from the blade assembly. The suspension support plate is designed to gradually thicken and then gradually thin, facilitating fluid flow and reducing the obstruction to fluid flow, thus ensuring the performance of the axial flow fan.

[0013] Preferably, in one of the suspension plates, the axial length of the rear portion is greater than or equal to 2 / 3 of the axial length of the suspension plate.

[0014] In this scheme, the boundary between the front and rear sections is the inflection point of the change in the thickness of the suspension plate. After the fluid flows through this boundary, it is easy to separate from the surface of the rear section. By setting the length of the rear section to be greater than or equal to 2 / 3 of the length of the suspension plate, the length of the rear section is large enough to facilitate the fluid to re-attach to the surface of the rear section when it flows through it.

[0015] Preferably, the tangents on the windward and leeward sides of at least the outer support portion of the front portion at the tail edge of the contour of the equal radius surface are parallel to the axial direction.

[0016] In this design, the layout facilitates a smooth transition between the front and rear sections, and suppresses the separation of fluid from the surface of the suspension plate.

[0017] Preferably, the absolute value of the angle between the tangents on the windward and leeward sides of at least the outer support portion of the rear portion at the leading edge point of the contour of the equal radius surface and the first direction is less than or equal to 2°.

[0018] In this design, the layout facilitates a smooth transition between the front and rear sections.

[0019] Preferably, the outer contour of the rear portion at the trailing edge of the equal radius surface is an elliptical arc, and the diameter of the smallest inscribed circle is less than or equal to 0.5 times the maximum thickness of the rear portion.

[0020] In this design, the thickness at the trailing edge of the rear section is sufficiently small, resulting in a small wake after the fluid flows over the suspension plate, minimal loss of hydrodynamic performance, and low noise.

[0021] Preferably, at least the outer branch portion of the front portion has a semi-circular arc or a semi-elliptical arc with its major axis parallel to the axial direction on the outer contour of the equal radius surface.

[0022] Preferably, the blade assembly includes a stationary blade mounted on a housing and a moving blade mounted on a rotating shaft, wherein in a single-stage blade assembly, the moving blade is disposed upstream of the stationary blade.

[0023] Ideally, all moving blades should have the same shape and size, and all stationary blades should have the same shape and size.

[0024] In this scheme, when all moving blades have the same shape and size, and all stationary blades have the same shape and size, repeating blade assemblies can be formed to create repeating-stage axial flow fans. Firstly, this improves the ease of manufacturing axial flow fans; secondly, it reduces processing costs; and thirdly, it allows for changes in the performance of axial flow fans by increasing or decreasing the number of blade assembly stages.

[0025] Preferably, the absolute value of the exit angle of the moving blade is greater than the absolute value of the exit angle of the stationary blade, and the exit angle of the stationary blade is between -20° and 20°.

[0026] In this design, the absolute value of the moving blade outlet angle is greater than that of the stationary blade outlet angle, with the stationary blade outlet angle ranging from -20° to 20°. This ensures that the fluid flow direction is essentially parallel to the axial direction after passing through the stationary blade. When it is a repeating-stage axial flow fan, the shape of the suspension support plate can reduce obstruction to fluid flow, ensuring that the fluid flow at each stage of the blade assembly is basically consistent, thereby fully utilizing the performance of the repeating-stage axial flow fan.

[0027] Preferably, the exit angle of the stationary blade is between -15° and 0°.

[0028] Preferably, the stationary blade and the moving blade are made of plastic or aluminum alloy.

[0029] In this design, the relatively soft plastic or aluminum alloy materials can reduce wear on the mold when casting the stationary and moving blades; the relatively light plastic or aluminum alloy materials can reduce the weight of the axial flow fan when used in the axial flow fan.

[0030] Preferably, the blade flow channel is formed between the outer surface of the rotating shaft and the inner surface of the housing, and the inner diameter of the housing and the outer diameter of the rotating shaft remain unchanged at least within the blade flow channel region.

[0031] In this design, the inner diameter of the casing and the outer diameter of the shaft remain constant within the blade flow channel region, ensuring a stable blade flow channel and facilitating full utilization of the performance of the repeating stage axial flow fan.

[0032] Preferably, the radius of the mounting component gradually increases along the axial direction toward the rotating shaft, and the maximum radius of the mounting component is equal to the minimum radius of the corresponding blade flow channel end.

[0033] In this design, the dimensions of the mounting components are designed to facilitate a smooth flow of fluid between the mounting components and the blade flow channels.

[0034] Preferably, the radius of the root of the suspension plate at the end closest to one end of the blade assembly along the axial direction is equal to the minimum radius of the corresponding blade flow channel end.

[0035] In this design, the radius of the suspension plate near the end of the blade assembly is equal to the minimum radius of the corresponding blade flow channel end. On the one hand, this reduces the obstruction to fluid flow; on the other hand, it makes the manufacturing process easier and facilitates axial demolding.

[0036] Preferably, the suspension plates are arranged symmetrically about the axial direction.

[0037] In this design, the suspension plate's obstruction to fluid flow is reduced, and the ease of manufacturing the suspension plate is improved.

[0038] Preferably, the suspension plate and the corresponding mounting component are integrally formed.

[0039] In this design, the configuration helps to reduce processing costs and minimize the number of assembly steps for the axial flow fan.

[0040] Preferably, the suspension plate further includes an inner support portion with a radius smaller than the minimum radius of the corresponding blade flow channel end, and the mounting member is at least mounted on the inner support portion.

[0041] In this solution, by setting an internal support section to install the mounting components, the axial space occupied by the rotating shaft can be reduced, which makes it easier to reduce the length of the rotating shaft. On the one hand, it can reduce the amount of material used and reduce the overall weight and cost of the axial flow fan; on the other hand, it can make the axial dimensions of the axial flow fan more compact.

[0042] Preferably, the number of each type of suspension support plate is multiple, and they are evenly spaced around the axial direction, and the average consistency of each type of suspension support plate is less than or equal to 1.

[0043] And / or, the number of each type of suspension support plate is ≤6.

[0044] In this design, the suspension supports are arranged sparsely enough to reduce their obstruction to fluid flow.

[0045] Preferably, the number of stages of the blade assembly is K, and the first stage blade assembly, the second stage blade assembly, ..., the Kth stage blade assembly are arranged sequentially along the first direction;

[0046] The blade assembly includes a stationary blade mounted on a housing and a moving blade mounted on a rotating shaft. In a single-stage blade assembly, the moving blade is located upstream of the stationary blade.

[0047] The average distance between the trailing edge of the i-th stage moving blade and the leading edge of the i-th stage stationary blade along the axial direction is drs_i, i = 1, 2, ..., K; the average distance between the trailing edge of the j-th stage stationary blade and the leading edge of the (j+1)-th stage moving blade along the axial direction is dsr_j, j = 1, 2, ..., K-1;

[0048] As i increases, as j increases, drs_i and dsr_j change monotonically in the same direction;

[0049] When K = 2, drs_1 ≠ drs_K;

[0050] When K > 2, drs_1 ≠ drs_K and / or dsr_1 ≠ dsr_K-1.

[0051] In this design, a larger drs_i in the axial flow fan results in more uniform mixing of the fluid as it flows from the trailing edge of the moving blade to the trailing edge of the stationary blade, thus improving blade frequency noise and reducing fluid flow noise. Similarly, a larger dsr_j results in more uniform mixing of the fluid as it flows from the trailing edge of the preceding stationary blade to the leading edge of the following moving blade, also improving blade frequency noise and reducing fluid flow noise.

[0052] As i and j increase, drs_i and dsr_j change monotonically in the same direction. Furthermore, when K = 2, drs_1 ≠ drs_K, and when K > 2, drs_1 ≠ drs_K and / or dsr_1 ≠ dsr_K-1. This ensures that drs_i and dsr_j are larger the closer they are to the inlet or outlet of the axial flow fan.

[0053] Firstly, when the values ​​of drs_i and dsr_j are larger closer to the inlet of the axial flow fan, the fluid is mixed more evenly at the blades closer to the inlet, and the noise generated by the fluid flow itself is smaller. Moreover, the noise generated by the fluid flow at the downstream blades, which is relatively greater than that at the upstream blades, is gradually weakened by the shielding of multiple rows of blades, thereby reducing the noise transmitted upstream. Therefore, the noise in the upstream part of the axial flow fan, especially at the inlet, can be reduced.

[0054] Secondly, similar to the first point, when the values ​​of drs_i and dsr_j are larger closer to the outlet of the axial flow fan, the fluid is mixed more evenly at the blades closer to the outlet, and the noise generated by the fluid flow itself is smaller. Moreover, the noise generated by the fluid flow at the upstream blades, which is relatively greater than that at the downstream blades, is gradually weakened by the shielding of multiple rows of blades, thereby reducing the noise transmitted downstream. Therefore, the noise in the downstream part of the axial flow fan, especially at the outlet, can be reduced.

[0055] Thirdly, it is possible to reduce the noise at the inlet or outlet of the axial flow fan while avoiding an increase in the axial dimension of the axial flow fan; or, while avoiding an increase in the noise at the inlet or outlet of the axial flow fan, it is possible to reduce the axial dimension of the axial flow fan.

[0056] Ideally, dsr_j ≥ drs_i, j = i;

[0057] And / or, dsr_j>drs_(i+1), j=i.

[0058] In this design, the axial spacing between the j-stage stationary blades and the j+1-stage moving blades is increased, which makes the fluid more evenly mixed when it flows from the front stationary blades to the leading edge of the rear moving blades, thus reducing the overall noise of the axial flow fan.

[0059] Ideally, dsr_j / drs_i should be in the range of 1.1 to 1.5, where j = i.

[0060] A range hood includes an axial flow fan as described in any of the above technical solutions, wherein the inlet of the axial flow fan is the inlet of the range hood or is connected to the inlet of the range hood, and the outlet of the axial flow fan is the outlet of the range hood or is connected to the outlet of the range hood.

[0061] A range hood includes an axial flow fan as described in any of the above technical solutions, wherein the inlet of the axial flow fan is the inlet of the range hood or is connected to the inlet of the range hood, and the outlet of the axial flow fan is the outlet of the range hood or is connected to the outlet of the range hood, drs_1≥drs_2≥……≥drs_K, dsr_1≥dsr_2≥……≥dsr_(K-1).

[0062] In this solution, an axial flow fan is used in the range hood. The inlet of the axial flow fan is closer to the user than the outlet. By setting drs_1≥drs_2≥……≥drs_K and dsr_1≥dsr_2≥……≥dsr_(K-1), the noise at the inlet of the axial flow fan can be reduced, thereby reducing the noise transmitted to the user.

[0063] The positive and progressive effects of this utility model are as follows:

[0064] In axial flow fans with multi-stage blade assemblies, mounting components and suspension plates are installed to install the rotating shaft, avoiding interference with the processing and manufacturing of other components in the axial flow fan and improving the ease of manufacturing the axial flow fan.

[0065] By setting the thickness of the front portion of the suspension support plate to gradually increase along the first direction, and ensuring that the absolute value of the angle between the tangent of the outer support portion of the front portion on the surface of equal radius and the first direction remains constant or gradually decreases, a natural draft angle is formed, facilitating demolding during casting manufacturing. Similarly, the thickness of the rear portion of the suspension support plate is set to gradually decrease along the first direction, and the absolute value of the angle between the tangent of the outer support portion of the rear portion on the surface of equal radius and the first direction remains constant or gradually increases, forming a natural draft angle for easy demolding during casting manufacturing. Furthermore, the radius of the outer support portion of the suspension support plate is greater than or equal to the minimum radius of the corresponding blade flow channel end. The outer support portion guides the fluid flow towards or from the blade assembly. The suspension support plate is designed to gradually thicken and then gradually thin, facilitating fluid flow and reducing the obstruction to fluid flow, thus ensuring the performance of the axial flow fan. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the range hood in Example 1;

[0067] Figure 2 This is a schematic diagram of the external structure of the axial flow fan in Example 1;

[0068] Figure 3 This is a schematic diagram of the internal structure of the axial flow fan in Example 1;

[0069] Figure 4 This is a schematic diagram of the front mounting component and front suspension support plate in Example 1;

[0070] Figure 5 This is a schematic diagram of the rear mounting component and rear suspension bracket in Example 1;

[0071] Figure 6 This is a meridional view of the axial flow fan in Example 2;

[0072] Figure 7 This is a schematic diagram of the axial flow fan with equal radius in Example 2;

[0073] Figure 8 This is a meridional view of the front suspension plate of the axial flow fan in Example 2;

[0074] Figure 9 This is a schematic diagram of the equal radius surface of the outer support portion of the front suspension plate in Example 2;

[0075] Figure 10 This is a meridional view of the rear suspension plate of the axial flow fan in Example 2;

[0076] Figure 11 This is a schematic diagram of the equal radius surface of the rear suspension support plate in Example 2;

[0077] Figure 12 This is a meridional view of the front suspension plate of the axial flow fan in another embodiment.

[0078] Explanation of reference numerals in the attached figures:

[0079] 1000 axial flow fan;

[0080] Housing 1, front housing 11, rear housing 12;

[0081] Blade assembly 2;

[0082] 21 moving leaves, 211 primary moving leaves, 212 secondary moving leaves, 213 tertiary moving leaves;

[0083] Static Leaf 22, Level 1 Static Leaf 221, Level 2 Static Leaf 222, Level 3 Static Leaf 223;

[0084] Shaft 3;

[0085] Mounting component 4, front mounting component 41, rear mounting component 42;

[0086] Suspension plate 5;

[0087] Front suspension support plate 51, first part 511, second part 512;

[0088] Rear suspension support plate 52, third part 521, fourth part 522, fifth part 523;

[0089] External branch 531, internal branch 532;

[0090] Front-mounted section 541, rear-mounted section 542;

[0091] Blade channel 6;

[0092] Smoke hood 2000, outer casing 3000;

[0093] Range hood 10000. Detailed Implementation

[0094] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0095] Example 1

[0096] This embodiment provides a range hood. Figures 1-5 This is a schematic diagram of the structure of this embodiment.

[0097] like Figure 1The range hood 10000 includes an axial flow fan 1000, a smoke collection hood 2000, and a housing 3000. The bottom of the smoke collection hood 2000 has an opening to serve as the inlet of the range hood 10000. The housing 3000 and the smoke collection hood 2000 are fixed together. The axial flow fan 1000 is installed inside the housing 3000. The inlet of the axial flow fan 1000 is connected to the inlet of the range hood 10000. The outlet of the axial flow fan 1000 forms the outlet of the range hood 10000.

[0098] In this embodiment, the length, width, and height directions of the range hood 10000 are X, Y, and Z, respectively. These three directions are perpendicular to each other, with the Z direction parallel to the vertical direction. In the accompanying drawings of this utility model, the Z-axis coincides with the axis of the axial flow fan 1000. The direction of the Z-axis is the direction from the inlet to the outlet of the axial flow fan 1000, which also corresponds to the direction in which the fluid flows from upstream to downstream in the axial flow fan 1000. For ease of description below, the direction of the Z-axis will be referred to as the "first direction".

[0099] In a preferred embodiment, the outlet inner diameter of the axial flow fan 1000 is between 160mm and 220mm, making it close to the inner diameter of commonly used general-purpose flue pipes, thus facilitating the connection between the outlet of the axial flow fan 1000 and the general-purpose flue pipe. Furthermore, setting the outlet inner diameter of the axial flow fan 1000 between 175mm and 185mm makes it close to the inner diameter of most general-purpose flue pipes, further improving the convenience of connecting the axial flow fan 1000 and the flue pipe.

[0100] In other embodiments, the shape and installation direction of the range hood 10000 can be adjusted according to usage requirements. The inlet of the axial fan 1000 can be used as the inlet of the range hood 10000, for example, when the smoke collection hood 2000 is not installed; or, the inlet of the axial fan 1000 and the inlet of the range hood 10000 can be connected. The outlet of the axial fan 1000 can be used as the outlet of the range hood 10000; or, the outlet of the axial fan 1000 and the outlet of the range hood 10000 can be connected by a pipe.

[0101] like Figure 2 , Figure 3 The axial flow fan 1000 includes a housing 1, a rotating shaft 3, and a K-stage blade assembly 2, where K=3. The rotating shaft 3 is housed within the housing 1. The single-stage blade assembly 2 includes two types of blades: moving blades 21 and stationary blades 22. Along the Z-direction, the first-stage moving blade 21, the first-stage stationary blade 22, the second-stage moving blade 21, the second-stage stationary blade 22, the third-stage moving blade 21, and the third-stage stationary blade 22 are arranged sequentially at intervals. The stationary blades 22 are mounted on the housing 1, and the moving blades 21 are mounted on the rotating shaft 3. Figure 2 The housing 1 of the axial flow fan 1000 includes a front housing 11 and a rear housing 12, and the flanges of the front housing 11 and the rear housing 12 are fixedly connected.

[0102] In this embodiment, by using a K-class design to achieve the pressure rise and flow rate of the single-stage axial fan 1000, the sound power can be reduced to 1 / K of the original. This allows the axial fan 1000 to maintain a low noise level while ensuring sufficient aerodynamic performance. Furthermore, the K-class blade assembly 2 is designed so that each row of blades blocks noise transmission, providing reflection and absorption, further reducing noise. Applying the K-class axial fan 1000 to the range hood 10000 results in good aerodynamic performance and low noise.

[0103] In other embodiments, the axial fan 1000 may be provided with two, three or more stages of blade assembly 2. By increasing the number of stages of blade assembly 2, the aerodynamic performance of the range hood 10000 can be improved, and the radial dimension of the axial fan 1000 can be made smaller, so as to reduce the space occupied by the axial fan 1000 in the X and Y directions in the kitchen.

[0104] like Figure 3 The axial flow fan 1000 also includes two types of suspension plates 5: a front suspension plate 51 and a rear suspension plate 52; and two types of mounting parts 4: a front mounting part 41 and a rear mounting part 42. The front suspension plate 51 and the front mounting part 41 correspond to each other and are used to be installed on the upstream end of the rotating shaft 3 along the axial direction. The rear suspension plate 52 and the rear mounting part 42 correspond to each other and are used to be installed on the downstream end of the rotating shaft 3 along the axial direction. Figure 4 , Figure 5 The diagram illustrates a three-dimensional effect. Specifically, the mounting component 4 and the rotating shaft 3 are rotatably connected at their axial ends, for example, through a bearing connection. The mounting component 4 is fixed to the housing 1 by a corresponding suspension plate 5, thereby enabling the rotating shaft 3 to rotate relative to the housing 1. The mounting component 4 and suspension plate 5 are used to mount the rotating shaft 3, avoiding interference with the manufacturing of other components in the axial flow fan 1000 and improving the ease of manufacturing the axial flow fan 1000.

[0105] Example 2

[0106] This embodiment provides an axial flow fan for use in a range hood. The arrangement of the axial flow fan in the range hood is as described in Embodiment 1. Figures 6-11 This is a schematic diagram of this embodiment.

[0107] like Figure 6 , Figure 7 The axial flow fan 1000 includes a housing 1, a rotating shaft 3, a three-stage blade assembly 2, a front suspension plate 51 and a front mounting component 41, a rear suspension plate 52 and a rear mounting component 42. The mounting component 4 and the suspension plate 5 are provided to mount the rotating shaft 3, avoiding interference with the processing and manufacturing of other components in the axial flow fan 1000, thus improving the ease of manufacturing the axial flow fan 1000.

[0108] The blade flow channel 6 is a well-known concept, referring to the flow channel range of the blade assembly 2 within the casing 1 of the axial flow fan 1000 along the Z-direction from the leading edge to the trailing edge. Figure 6 The Z_YPLD diagram illustrates the range of the blade flow channel 6 along the Z-direction. For example... Figure 6 A blade flow channel 6 is formed between the inner surface of the housing 1 and the surfaces of other components in the housing 1 except for the blade assembly 2. In this embodiment, the blade flow channel 6 is specifically formed by the inner surface of the housing 1 and the outer surface of the rotating shaft 3; the blade assembly 2 is disposed in the blade flow channel 6.

[0109] like Figure 6 The minimum radius at both ends of the blade flow channel 6 along the axial direction is r1. Both the front suspension plate 51 and the rear suspension plate 52 have an outer support portion 531 with a radius greater than r1 and an inner support portion 532 with a radius less than r1; for ease of understanding, Figure 8 , Figure 10 The dashed line in the diagram roughly indicates the boundary between the outer support portion 531 and the inner support portion 532 of the suspension support plate 5. By providing the inner support portion 532 to mount the mounting member 4 onto the corresponding inner support portion 532 of the suspension support plate 5, the axial space occupied by the rotating shaft 3 can be reduced, facilitating a reduction in the length of the rotating shaft 3. On the one hand, this reduces material usage, lowering the overall weight and cost of the axial flow fan 1000; on the other hand, it allows for a more compact axial dimension of the axial flow fan 1000. In other embodiments, the mounting member 4 may not have the inner support portion 532, for example... Figure 12 The schematic diagram shows the structure of the suspension support plate 5.

[0110] The thickness of both types of suspension plates 5 gradually increases and then gradually decreases along the Z-axis. The gradually increasing portion is the front portion 541, and the gradually decreasing portion is the rear portion 542. This arrangement facilitates the smooth passage of fluid through the suspension plates 5 and reduces the obstruction to fluid flow caused by the suspension plates 5. The thickness T of the suspension plate 5 can be found in [reference needed]. Figure 9 The annotations in the text. Figure 9 , Figure 11 The dashed lines L1 and L4 indicate the approximate boundaries between the front part 541 and the rear part 542, respectively.

[0111] Figure 9 The diagram illustrates the outline of the outer support portion 531 of the front suspension mount 51 on a surface of equal radius. This surface is a virtual cylindrical surface with the axis of rotation 3 as its axis. The direction of rotation of the shaft 3 is represented by W in the diagram, and the arrow pointing in the W direction points from the windward side to the leeward side. The front portion 541 and the rear portion 542 of the outer support portion 531 of the front suspension mount 51 will be referred to as "first part 511" and "second part 512," respectively. Figure 9In the first part 511, the absolute value of the angle between the tangent direction of the windward and leeward sides of the contour of the equal-radius surface and the Z-direction gradually decreases. On the one hand, this causes the fluid flow direction to gradually become parallel to the axial direction when passing through the first part 511; on the other hand, it can form a draft angle, facilitating demolding in the opposite direction of the Z-direction. In the second part 512, the absolute value of the angle between the tangent direction of the windward and leeward sides of the contour of the equal-radius surface and the Z-direction gradually increases. This causes the fluid flow to gradually converge and have a small wake when passing through the second part 512; on the other hand, it can form a draft angle, facilitating demolding in the Z-direction. In this embodiment, within the equal-radius surface, the contour tangent is used with the opposite directions of the Z and W directions as two-dimensional coordinate axes, and the slope of the contour tangent is positive, that is, the angle between the tangent and the Z-direction is positive. Figure 9 The diagram shows the outline tangent L2 of point P2 on the windward surface of the second part 512 on the surface of equal radius. The angle between L2 and the Z direction is negative.

[0112] Figure 11 The outlines of the outer support portion 531 and the inner support portion 532 of the rear suspension support plate 52 on a surface of equal radius are shown. Figure 11 The dashed curve L5 represents the outer contour of the rear mounting component 42. The outer support portion 531 of the front portion 541, the outer support portion 531 of the rear portion 542, and the inner support portion 532 of the rear portion 542 are respectively referred to as "third part 521," "fourth part 522," and "fifth part 523." Figure 11 In the third part 521, the absolute value of the angle between the tangent direction of the windward and leeward sides of the contour of the equal-radius surface and the Z-direction gradually decreases. On the one hand, this causes the fluid flow direction to gradually become parallel to the axial direction when passing through the third part 521; on the other hand, it can form a draft angle, facilitating demolding in the opposite direction of the Z-direction. In the fourth part 522 and the fifth part 523, the absolute value of the angle between the tangent direction of the windward and leeward sides of the contour of the equal-radius surface and the Z-direction gradually increases. This causes the fluid flow to gradually converge and have a small wake when passing through the fourth part 522 and the fifth part 523; on the other hand, it can form a draft angle, facilitating demolding in the Z-direction.

[0113] In this invention, the shape of the suspension support plate 5 is designed to minimize its impact on fluid flow, thereby avoiding any negative impact on the aerodynamic and noise reduction performance of the axial flow fan 1000. In other embodiments, the absolute values ​​of the angles between the tangents of the windward and leeward sides of the outer support plate 531 on the plane of equal radius and the Z-direction in the front portion 541 can be kept constant or gradually decreased, while the absolute values ​​of the angles between the tangents of the windward and leeward sides of the outer support plate 531 on the plane of equal radius and the Z-direction in the rear portion 542 can be kept constant or gradually increased.

[0114] In this embodiment, both types of suspension plates 5 are cast in shape, manufactured by double-sided molding along the Z-direction and the opposite direction of the Z-direction, respectively. Figure 9, Figure 11 L1 and L4 are used as parting lines.

[0115] In a preferred embodiment, the length of the rear portion 542 along the Z direction in the two types of suspension plates 5 is greater than or equal to 2 / 3 of the axial length of the suspension plate 5 in which it is located. It is understood that the length comparison is made at the same radius. After the fluid flows through the boundary between the front portion 541 and the rear portion 542, the fluid will separate from the surface of the suspension plate 5 due to the presence of the parting line. By setting the axial length of the rear portion 542 to be long enough, the fluid can re-attach to the surface of the rear portion 542.

[0116] In a preferred embodiment, the tangents of the windward and leeward sides of the outer support portion 531 of the front portion 541 of the two suspension plates 5 at the tail edge points of the contour of the equal radius surface are parallel to the Z direction, so that the fluid flows closer to the axial direction after passing through the front portion 541, and flows smoothly to the rear portion 542, reducing the obstruction of the suspension plates 5 to the fluid flow and suppressing the separation of the fluid from the surface of the suspension plates 5. Figure 9 The diagram shows the tangent L3 at point P3 on the windward surface of the first part 511, which is parallel to the Z-axis.

[0117] In a preferred embodiment, the front portion 541 of the suspension plate 5 has a semi-circular arc or a semi-elliptical arc with its major axis parallel to the axial direction on the outer contour of the equal radius surface, so as to facilitate a smooth transition from the front portion 541 to the rear portion 542. Preferably, a semi-elliptical arc with its major axis parallel to the axial direction is adopted, which facilitates reducing the maximum thickness of the suspension plate 5 and further reduces the obstruction to fluid flow.

[0118] In a preferred embodiment, the absolute value of the angle between the tangents on the windward and leeward sides of the rear portion 542 of the two types of suspension plates 5 at the leading edge point of the contour of the equal radius surface and the Z-direction is less than or equal to 2°, which facilitates a smooth transition between the front portion 541 and the rear portion 542. An angle less than 1° is even better, resulting in a smoother transition. In other embodiments, this value can be adjusted according to the required draft angle.

[0119] In a preferred embodiment, the outer contour of the rear portion 542 of both types of suspension plates 5 at the trailing edge of the equal-radius surface is elliptical, and the diameter of the smallest inscribed circle is less than or equal to 0.5 times the maximum thickness of the rear portion 542. This ensures that the thickness at the trailing edge of the rear portion 542 is sufficiently small, resulting in a small wake after fluid flows over the suspension plate 5, minimal loss of hydrodynamic performance, and low noise. The effect is even better when the diameter of the smallest inscribed circle is less than or equal to 0.3 times the maximum thickness of the rear portion 542.

[0120] The blade assembly 2 includes two types of blades: stationary blades 22 and moving blades 21. In the same stage of the blade assembly 2, the stationary blades 22 are located downstream of the moving blades 21. In a preferred embodiment, all moving blades 21 have the same shape and size, and all stationary blades 22 have the same shape and size, which can form repeating blade assemblies 2, forming repeating-stage axial flow fans 1000. Firstly, this can improve the ease of manufacturing the axial flow fan 1000; secondly, it can reduce processing costs; and thirdly, it is convenient to change the performance of the axial flow fan 1000 by increasing or decreasing the number of stages of the blade assembly 2.

[0121] In a preferred embodiment, such as Figure 7 The absolute value of the outlet angle β2 of the moving blade 21 is greater than the absolute value of the outlet angle β4 of the stationary blade 22. β4 is between -20° and 20°, ensuring that the fluid flow direction is basically parallel to the axial direction after passing through the stationary blade 22. When it is a repeating stage axial flow fan 1000, the shape of the suspension support plate 5 in this invention can reduce the obstruction to fluid flow, making the fluid flow at each stage blade assembly 2 basically consistent, so as to fully utilize the performance of the repeating stage axial flow fan 1000. When β4 is between -15° and 0°, the fluid flow direction after passing through the stationary blade 22 is even more parallel to the axial direction. The definition of the outlet angle is consistent with that in American textbooks, which is the angle between the tangent direction of the arc line at the trailing edge of the blade and the Z-direction. Figure 7 In the middle, β4 is positive, and the trailing edge of the stationary blade 22 points in the same direction as the rotor's rotational linear velocity.

[0122] In a preferred embodiment, the stationary blade 22 and the moving blade 21 are made of plastic or aluminum alloy. Plastic or aluminum alloy is relatively soft, which can reduce wear on the mold when manufacturing the stationary blade 22 and the moving blade 21 by casting; plastic or aluminum alloy is relatively light, which can reduce the weight of the axial flow fan 1000.

[0123] Consistency is a well-known concept. Blade consistency can be understood as the chord length of the blade divided by the distance between two adjacent blades in a single row. In a preferred embodiment, the maximum consistency of the single row of stationary blades 22 and the single row of moving blades 21 can be set to less than or equal to 1.8, ensuring that the blades in a single row are arranged sparsely enough to facilitate demolding during casting. Setting the maximum consistency of a single row of blades to less than or equal to 1.4 yields even better results.

[0124] like Figure 6A blade flow channel 6 is formed between the inner surface of the housing 1 and the outer surface of the rotating shaft 3. The axial range of the blade flow channel 6 is indicated by Z_YPLD in the figure. The outer surface radius of the rotating shaft 3 is constant at least at the blade flow channel 6, which is r1, and the inner surface radius of the housing 1 is constant at least at the blade flow channel 6, which makes the inner and outer diameters of the blade flow channel 6 constant. On the one hand, this makes the blade flow channel 6 simple in structure and easy to manufacture; on the other hand, it makes the blade flow channel 6 stable, which makes it easier to fully utilize the aerodynamic and noise reduction performance of the repeating stage axial flow fan 1000.

[0125] In a preferred embodiment, the hub ratio of the blade flow channel 6 is r1 / r2, ranging from 0.4 to 0.8, which makes the hub ratio large enough, thereby making the blade height small enough, so that the blade tip and root curvature can be set small, the fluid flow is smooth, and the noise is low; and the hub ratio is small enough, thereby making the blade height large enough, so that the channel through which the fluid flows through the blade is large enough, and the flow rate is large enough.

[0126] In a preferred embodiment, such as this embodiment, the front suspension plate 51 is arranged symmetrically about the axial direction. See [reference needed]. Figure 9 The rear suspension support plate 52 is symmetrically arranged about the axial direction, see [reference]. Figure 11 The suspension plate 5 is symmetrical about the axis and forms straight blades that extend along the axis. On the one hand, it can reduce the obstruction of fluid flow by the suspension plate 5, and on the other hand, it can improve the convenience of processing and manufacturing the suspension plate 5.

[0127] In a preferred embodiment, the suspension support plate 5 and the corresponding mounting component 4 are integrally formed, including but not limited to machining, casting, etc. In this embodiment, the suspension support plate 5 and the corresponding mounting component 4 are integrally formed by casting.

[0128] In a preferred embodiment, such as Figure 8 The radius of the front mounting part 41 gradually increases along the Z direction, with the maximum radius equal to r1; for example Figure 10 The radius of the rear mounting part 42 gradually decreases along the Z direction, with the maximum radius equal to r1. On the one hand, this allows for a smooth transition between the surfaces of the two mounting parts 4 and the inner wall of the blade flow channel, facilitating the smooth flow of fluid. On the other hand, it facilitates the formation of a draft angle, allowing for axial draft when the mounting part 4 is cast.

[0129] In a preferred embodiment, such as Figure 8 The radius at the trailing edge point P1 of the front suspension support plate 51 is equal to r1, which improves the ease of integral manufacturing of the front suspension support plate 51 and the front mounting part 41. For example, during integral casting, the rear part 542 of the front suspension support plate 51 can be drafted along the Z direction. Figure 10The radius at the tail edge point P4 of the rear suspension support plate 52 is equal to r1, which can improve the convenience of manufacturing the rear suspension support plate 52 and the rear mounting part 42 as a whole. For example, when casting as a whole, the front part 541 of the rear suspension support plate 52 can be demolded in the opposite direction of the Z direction.

[0130] In a preferred embodiment, the number of front suspension plates 51 is six and the number of rear suspension plates 52 is four. Setting the number of suspension plates 5 to six or less helps to reduce the obstruction of fluid flow by the suspension plates 5.

[0131] Average consistency is a well-known concept and can be understood as the average consistency at different radii. In a preferred embodiment, the average consistency of both the front suspension plate 51 and the rear suspension plate 52 is less than or equal to 1, making the suspension plates 5 sparsely arranged, which can reduce the obstruction of the suspension plates 5 to fluid flow.

[0132] like Figure 6 The average distance between the trailing edge of the i-th stage moving blade 21 and the leading edge of the i-th stage stationary blade 22 is drs_i, where i = 1, 2, ..., K. As i increases, drs_i decreases, meaning that the closer to the inlet of the axial flow fan 1000, the larger drs_i becomes. K = 3, and the corresponding drs_i are drs_1, drs_2, and drs_3, where drs_1 > drs_2 > drs_3. The average distance can be understood as the average distance at different blade heights. Figure 6 The spacing at a certain blade height is simplified and labeled as the average spacing.

[0133] like Figure 6 The average distance along the Z-direction between the trailing edge of the j-th stage stationary blade 22 and the leading edge of the (j+1)-th stage moving blade 21 is dsr_j, where j = 1, 2, ..., K-1. As j increases, dsr_j decreases, meaning that the closer to the inlet of the axial flow fan 1000, the larger dsr_j becomes. When K = 3, dsr_j are dsr_1 and dsr_2, respectively, and dsr_1 > dsr_2. In other embodiments, if two-stage blade assemblies 2 are provided, corresponding to one dsr_j, i.e., dsr_1, it can be considered that dsr_j decreases or increases with the number of stages.

[0134] In a range hood 10000, the inlet is generally closer to the user than the outlet. The closer the axial flow fan 1000 is to the inlet, the greater the noise impact on the user. A larger drs_i ensures more uniform mixing of the fluid as it flows from the trailing edge of the moving blade 21 to the trailing edge of the stationary blade 22, thus improving blade frequency noise and reducing fluid flow noise. In a range hood 10000, the closer the drs_i and dsr_j are to the inlet, the larger they are. On one hand, the more uniform the airflow is mixed at the blades closer to the inlet, the lower the noise generated by the airflow itself, and the less noise is transmitted to the user. On the other hand, although a smaller drs_i and dsr_j are closer to the outlet, resulting in greater noise at the downstream blades than at the upstream blades, the closer the axial flow fan 1000 is to the outlet, the greater the noise impact on the user. The farther away from the user, the less impact the noise has on the user. Also, the closer to the outlet of the axial fan 1000, the greater the noise generated by the airflow. When it reaches the inlet of the axial fan 1000, it needs to pass through more rows of blades to be blocked. This causes the noise generated at the downstream blades to gradually weaken as it is transmitted upstream, thereby reducing the noise transmitted to the user. Combining these two aspects, the upstream part of the axial fan 1000, especially at the inlet, has less noise, thus reducing the noise transmitted from the range hood 10000 to the user.

[0135] If the noise level at the inlet of the axial flow fan 1000 is kept consistent, compared to a scheme where all drs_i and dsr_j are the same, this embodiment, by setting drs_i and dsr_j to be larger the closer they are to the inlet of the axial flow fan 1000, facilitates a reduction in the axial dimension of the axial flow fan 1000, resulting in a more compact structure. If the axial dimension of the axial flow fan 1000 is kept constant, compared to a scheme where all drs_i and dsr_j are the same, this embodiment, by setting drs_i and dsr_j to be larger the closer they are to the inlet of the axial flow fan 1000, can significantly reduce the noise at the inlet of the axial flow fan 1000. In the range hood 10000, the inlet of the range hood 10000 is generally closer to the user than the outlet. This makes the upstream blade assembly 2 of the axial flow fan 1000 closer to the user. By setting drs_i and dsr_j to decrease, the noise transmitted from the axial flow fan 1000 to the user can be reduced. At the same time, the compact structure of the axial flow fan 10000 can also be maintained. Thus, the range hood 10000 can achieve both compact structure and low noise.

[0136] In other embodiments, it can be set that as i increases, drs_i and dsr_j change monotonically in the same direction; when K = 2, drs_1 ≠ drs_K; when K > 2, drs_1 ≠ drs_K and / or dsr_1 ≠ dsr_K-1. This can reduce the noise at the inlet or outlet of the axial flow fan 1000, or it can balance the axial dimensions and noise reduction performance of the axial flow fan 1000. For example, drs_1 ≥ drs_2 …… ≥ drs_K, and dsr_1 ≥ dsr_2 …… ≥ drs_K-1; or drs_1 ≤ drs_2 …… ≤ drs_K, and dsr_1 ≤ dsr_2 …… ≤ drs_K-1, can all be considered as drs_i and dsr_j changing monotonically in the same direction.

[0137] In other embodiments, the axial flow fan 1000 of this embodiment or other embodiments can be applied to other scenarios besides the range hood 10000.

[0138] In other embodiments, when the inlet of the axial flow fan 1000 is closer to the user than the outlet, drs_1≥drs_2≥……≥drs_K, dsr_1≥dsr_2≥……≥dsr_(K-1) can be set. When K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1. This can reduce the noise at the inlet of the axial flow fan 1000, thereby reducing the noise transmitted to the user, or it can balance the axial dimension and noise reduction performance of the axial flow fan 1000. Furthermore, setting drs_1>drs_2>……>drs_K, dsr_1>dsr_2>……>dsr_(K-1) is even more effective.

[0139] In other embodiments, when the outlet of the axial flow fan 1000 is closer to the user than the inlet, such as in air supply equipment like air conditioners or blowing devices, drs_1≤drs_2≤……≤drs_K, dsr_1≤dsr_2≤……≤dsr_(K-1) can be set. When K=2, drs_1≠drs_K; when K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1, making the noise at the outlet of the axial flow fan 1000 smaller, thereby reducing the noise transmitted to the user. Furthermore, setting drs_1<drs_2<……<drs_K, dsr_1<dsr_2<……<dsr_(K-1) is even better.

[0140] In other embodiments, the primary stationary blade 22 or the moving blade 21 may have only one row of blades; or, a single moving blade 21 or a single stationary blade 22 may be formed by connecting multiple rows of blades in series. In this case, for the primary blade, the leading edge of the first row of blades in the multiple rows of blades is considered to be the leading edge of the blade of that level, and the trailing edge of the last row of blades is considered to be the trailing edge of the blade of that level.

[0141] In a preferred embodiment, by setting dsr_j > drs_i, j = i, that is, the axial spacing between the j-stage stationary blade 22 and the j+1-stage moving blade 21 is greater than the axial spacing between the j-stage moving blade 21 and the j-stage stationary blade 22; and / or, by setting dsr_j > drs_(i+1), j = i, that is, the axial spacing between the j-stage stationary blade 22 and the j+1-stage moving blade 21 is greater than the axial spacing between the j+1-stage moving blade 21 and the j+1-stage stationary blade 22; the axial spacing between the j-stage stationary blade 22 and the j+1-stage moving blade 21 can be increased, so that the fluid is mixed more evenly when flowing from the front stage stationary blade 22 to the leading edge of the rear stage moving blade 21, thereby reducing the overall noise of the axial flow fan 1000.

[0142] In a preferred embodiment, j = i, and the range of dsr_j / drs_i is between 1.1 and 1.5. This allows the values ​​of dsr_j and drs_i to be large enough to reduce the noise of the axial fan 1000, while also ensuring that dsr_j and drs_i are small enough to prevent the axial dimension of the axial fan 1000 from being too large.

[0143] Overall, the axial flow fan 1000 provided by this utility model has the following advantages:

[0144] 1. The axial flow fan 1000 is small in size and occupies little space when used in the range hood 10000. Its layout in the air duct is flexible and free, which facilitates noise reduction design. Because the axial flow fan 1000 has the characteristic of straight airflow, it is very easy to stack multiple stages without bringing high complexity to the structure. When applied to the range hood 10000, multi-stage blade assembly 2 is set to distribute the pressure rise, thereby achieving a significant reduction in noise.

[0145] 2. The blades of the axial flow fan 1000 are usually twisted, which causes inconvenience in processing. This utility model improves the problem of high processing cost of the axial flow fan 1000 through the following aspects:

[0146] 2-1. The moving blades 21 and stationary blades 22 are the same for each stage. The blade mold of the whole product only needs two sets of moving blades 21 and stationary blades 22. The aerodynamic performance of the axial flow fan 1000 can be changed by increasing or decreasing the number of stages of the blade assembly 2, so that the axial flow fan 1000 can be applied to products with different performance specifications and reduce processing costs.

[0147] 2-2. Use softer materials such as plastic or aluminum alloy to make the blades, thereby reducing mold wear;

[0148] 2-3. By setting the blade consistency, it is easy for the blade to rotate bidirectionally for demolding;

[0149] 2-4. The moving blades 21 of each stage have the same shape and size, and the stationary blades 22 of each stage have the same shape and size, so as to reduce the manufacturing cost of the axial flow fan 1000 and make it easy to increase or decrease the number of stages of the blade assembly 2 to adjust the performance of the axial flow fan 1000.

[0150] 2-5. The multi-stage blade assembly 2 is set up to achieve the target pressure rise, so the load on each stage blade assembly 2 is relatively light and the blade twisting degree is relatively low, which also reduces the processing difficulty.

[0151] 3. In the axial flow fan 1000 with multi-stage blade assemblies 2 in the range hood 10000, the aerodynamic noise of the first-stage blade assembly 2 is directly transmitted to the inlet of the range hood 10000. However, the aerodynamic noise of subsequent stages of blade assemblies 2 is blocked by several rows of blades before reaching the inlet of the range hood 10000, and the noise transmitted from the later stages is blocked by more blades. Therefore, the earlier stages contribute more to the noise perceived by the user. Therefore, in this utility model, both drs_i and dsr_j decrease as the number of stages increases, thereby weakening the pulsating noise generated at the upstream blade assembly 2 and reducing the overall noise perceived by the user.

[0152] 4. The thickness of the outer support portion 531 of both types of suspension plates 5 gradually increases and then gradually decreases along the Z-direction, which helps reduce fluid flow loss and facilitates bidirectional drafting along the axial direction. Furthermore, by setting the length of the front portion 541 along the Z-direction in both types of suspension plates 5 to be less than or equal to 1 / 3 of the axial length of the suspension plate 5 it belongs to, the axial length of the rear portion 542 is sufficiently long so that the fluid can adhere to the surface of the rear portion 542 after flowing through the parting line. By setting the front portion 541 to a semi-circular or semi-elliptical shape, the fluid flows closer to the axial direction after passing through the parting line, which helps suppress separation.

[0153] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model 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 this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A centrifugal fan, comprising: a housing; a rotating shaft arranged in the housing; and at least two stages of blade assemblies arranged in blade passages in sequence along an axial direction of the rotating shaft, characterized in that the centrifugal fan further comprises at least one mounting member arranged and rotatably connected to an axial end of the rotating shaft, and at least one suspension support plate fixedly connected with the housing and the corresponding mounting member, wherein a single suspension support plate is arranged upstream or downstream of the blade assemblies; a thickness of the suspension support plate gradually increases to form a front portion and then gradually decreases to form a rear portion along the axial direction towards a first direction of an outlet of the centrifugal fan, wherein the suspension support plate has at least an outer portion with a radius greater than or equal to a minimum radius of an end of the corresponding blade passage, and an absolute value of an included angle between a profile tangent of an equal-radius surface of at least the windward surface and the leeward surface of the outer portion in the front portion and the first direction remains unchanged or gradually decreases, and an absolute value of an included angle between a profile tangent of an equal-radius surface of at least the windward surface and the leeward surface of the outer portion in the rear portion and the first direction remains unchanged or gradually increases. In a single suspension support plate, a length of the rear portion along the axial direction is greater than or equal to 2 / 3 of a length of the suspension support plate along the axial direction. And / or, a tangent line of the windward surface and the leeward surface of at least the outer portion in the front portion at a profile tail edge point of the equal-radius surface is parallel to the axial direction. And / or, an absolute value of an included angle between a profile tangent of the windward surface and the leeward surface of at least the outer portion at a profile leading edge point of the equal-radius surface and the first direction is less than or equal to 2°. And / or, an outer profile of a tail edge portion of the equal-radius surface in the rear portion is in an elliptical arc shape, and a diameter of a minimum inscribed circle is less than or equal to 0.5 times a maximum thickness of the rear portion. An outer profile of at least the outer portion in the front portion of the equal-radius surface is in a semicircular arc shape or a semi-elliptical arc shape with a major axis parallel to the axial direction.

2. The axial fan as set forth in claim 1, wherein The blade assembly comprises stationary vanes mounted on the housing and rotating vanes mounted on the rotating shaft, and in a single stage of the blade assembly, the rotating vanes are arranged upstream of the stationary vanes. All the rotating vanes have the same shape and size, and all the stationary vanes have the same shape and size; and / or, an absolute value of an outlet angle of the rotating vanes is greater than an absolute value of an outlet angle of the stationary vanes, and the outlet angle of the stationary vanes is between -20° and 20°. The outlet angle of the stationary vanes is between -15° and 0°. And / or, the stationary vanes and the rotating vanes are made of plastic or aluminum alloy.

3. The axial fan of claim 2, wherein The blade passage is formed between an outer surface of the rotating shaft and an inner surface of the housing, and an inner diameter of the housing and an outer diameter of the rotating shaft remain unchanged at least in the blade passage region.

4. The axial fan of claim 1 wherein, A radius of the mounting member gradually increases along the axial direction towards the rotating shaft, and a maximum radius of the mounting member is equal to a minimum radius of an end of the corresponding blade passage; and / or, a radius of an end point of a root of the suspension support plate close to one end of the blade assembly along the axial direction is equal to the minimum radius of the end of the corresponding blade passage. The suspension support plate is arranged symmetrically about the axial direction.

5. The axial fan of claim 4, wherein And / or, the suspension support plate and the corresponding mounting member are integrally formed. ​ 6. The axial fan as set forth in any one of claims 1 or 4, wherein ​ ​ 7. The axial fan according to claim 1, wherein ​ ​ 8. The axial fan of claim 1 wherein, The suspension support plate further comprises an inner support part with a radius smaller than the minimum radius of the corresponding blade flow passage end part, and the mounting member is mounted on at least the inner support part.

9. The axial fan of claim 1 wherein, The number of single suspension support plates is multiple, and the single suspension support plates are uniformly arranged along the axial direction. The number of single suspension support plates is less than or equal to 6.

10. The axial fan of claim 1 wherein, The number of stages of the blade assembly is K, the first-stage blade assembly, the second-stage blade assembly, …, and the K-stage blade assembly are arranged in sequence along the first direction. The blade assembly comprises a stationary blade mounted on a housing and a moving blade mounted on a rotating shaft, and in a single-stage blade assembly, the moving blade is arranged upstream of the stationary blade. The average distance between the trailing edge of the i-stage moving blade and the leading edge of the i-stage stationary blade along the axial direction is drs_i, i = 1, 2, …, K, and the average distance between the trailing edge of the j-stage stationary blade and the leading edge of the j+1-stage moving blade along the axial direction is dsr_j, j = 1, 2, …, K-1. As i increases, as j increases, drs_i and dsr_j monotonically change in the same direction. When K = 2, drs_1 ≠ drs_K. When K > 2, drs_1 ≠ drs_K and / or dsr_1 ≠ dsr_K-1.

11. The axial fan of claim 10, wherein dsr_j ≥ drs_i, j = i. And / or, dsr_j > drs_(i+1), j = i.

12. The axial fan of claim 10, wherein, The range of dsr_j / drs_i is between 1.1 and 1.5, j = i.

13. A range hood characterized by It comprises the axial flow fan according to any one of claims 1-9, the inlet of the axial flow fan is the inlet of the range hood or communicates with the inlet of the range hood, and the outlet of the axial flow fan is the outlet of the range hood or communicates with the outlet of the range hood.

14. A range hood characterized by It comprises the axial flow fan according to any one of claims 10-12, the inlet of the axial flow fan is the inlet of the range hood or communicates with the inlet of the range hood, and the outlet of the axial flow fan is the outlet of the range hood or communicates with the outlet of the range hood, drs_1 ≥ drs_2 ≥ … ≥ drs_K, and dsr_1 ≥ dsr_2 ≥ … ≥ dsr_(K-1).

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