Axial flow fan, injection system and range hood

Abstract

The invention discloses an axial flow fan, an injection system and a range hood, and relates to the technical field of kitchen electric appliances. The axial flow fan comprises a rectification air duct and a movable blade assembly, and a noise reduction groove penetrating in the circumferential direction is formed in the inner wall of the rectification air duct; the movable blade assembly comprises a movable impeller, the movable impeller is rotationally arranged in the rectification air duct, the movable impeller comprises a plurality of movable blades arranged at intervals in the circumferential direction, and the blade tops of the movable blades are located in the noise reduction grooves. The axial flow fan can reduce noise and improve aerodynamic performance so as to improve user experience.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen appliances, and in particular to an axial flow fan, an ejection system and a range hood. Background Art

[0002] The fan system of the range hood includes centrifugal fan system and axial flow fan system. Among them, the centrifugal fan system is relatively complex, with a large structure and high application cost. The axial flow fan system can be designed to be more compact, which can realize miniaturization of products and more flexible installation and appearance design in the kitchen environment with limited space.

[0003] However, axial flow fans also have the technical problem of high noise when achieving high speeds, especially the aerodynamic noise easily caused by airflow passing through the gap between the blade tips, which affects the user experience. Summary of the invention

[0004] The purpose of the present invention is to provide an axial flow fan, an ejection system and a range hood, which can reduce noise, improve aerodynamic performance, and enhance user experience.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] An axial flow fan, comprising:

[0007] A rectifier air duct, the inner wall of which is provided with a noise reduction groove that runs through the circumference;

[0008] The moving blade assembly includes a moving impeller, which is rotatably arranged in the rectifying air cylinder. The moving impeller includes a plurality of moving blades arranged at intervals along the circumferential direction, and the blade tops of the plurality of moving blades are located in the noise reduction groove.

[0009] As an optional solution for the above-mentioned axial flow fan, the noise reduction groove includes a bottom surface, along the radial direction of the rectifying air cylinder, the rotation radius of the bottom surface is Rs, the rotation radius of the inner wall of the rectifying air cylinder is Rc, and the blade tip radius of the moving blade is Rb, then Rs>Rb>Rc.

[0010] As an optional solution for the above axial flow fan, the distance between the blade tip and the bottom surface δ=Rs-Rb, and the depth of the blade tip entering the noise reduction groove λ=Rb–Rc, then

[0011] As an optional solution of the above-mentioned axial flow fan, along the axial direction of the rectifying air cylinder, the bottom surface is alternately provided with annular protrusions and annular grooves.

[0012] As an optional solution of the above axial flow fan, the annular protrusion and the annular groove are both arcs, and the radius of the arc is Rt, and the average distance between the blade top and the bottom surface δ'=Rs-Rb, then

[0013] As an optional solution for the above-mentioned axial flow fan, the bottom surface has a wave section along the axial direction of the rectifying air duct, and the cross-sectional figure of the surface of the wave section along the radial direction of the rectifying air duct is a sine curve and satisfies the sinusoidal curve equation y=h*sin(k*x),x∈[0,2π].

[0014] As an alternative to the above axial flow fan, in the sinusoidal curve equation,

[0015] As an alternative to the above axial flow fan, the average distance between the blade tip and the bottom surface δ" = Rs-Rb, then

[0016] As an optional solution of the above-mentioned axial flow fan, the axial flow fan also includes a stator blade assembly, the stator blade assembly includes a stator impeller, the stator impeller includes a plurality of stator blades arranged at intervals along the circumferential direction, the plurality of stator blades are all connected to the inner wall of the rectifier air duct, and the stator impeller is configured to decelerate the airflow passing through the moving impeller.

[0017] As an optional solution of the above-mentioned axial flow fan, the moving blade assembly is arranged on the stationary blade assembly.

[0018] An ejection system comprises any one of the above-mentioned axial flow fans and an ejection air cylinder, wherein the axial flow fan is arranged in the ejection air cylinder.

[0019] As an optional scheme for the above-mentioned induced draft system, along the axial direction of the induced draft wind tube, the induced draft wind tube includes an air inlet section, a throat section and an air outlet section in sequence, the inner diameter of the throat section is smaller than the inner diameter of the air inlet section and the inner diameter of the air outlet section, the axial flow fan is arranged in the air inlet section, and the outer diameter of the axial flow fan is smaller than the inner diameter of the air inlet section.

[0020] As an alternative to the above-mentioned ejection system, the inner wall radius of the air inlet section is Ri, and the tip radius of the moving blade is Rb, then

[0021] A range hood comprises an educing system.

[0022] Beneficial effects of the present invention:

[0023] The present invention provides an axial flow fan, an ejection system and a range hood. The inner wall of the rectifying air duct of the axial flow fan is provided with a noise reduction groove. When the impeller rotates, since the blade tops of the impeller blades are located in the noise reduction groove, the high-speed airflow flowing along the inner side of the rectifying air duct will not directly pass through the blade tip gap of the impeller blade. Therefore, the airflow velocity between the blade tops of the impeller blades and the inner wall of the rectifying air duct is relatively low, thereby reducing the noise in the turbulent flow area of ​​the blade tip gap. Moreover, the provision of the noise reduction groove can also reduce the disturbance of the turbulent flow in the mainstream area caused by the change in flow velocity and direction caused by the blade tip gap, thereby effectively improving the aerodynamic performance of the axial flow fan.

[0024] The axial flow fan can reduce noise and improve aerodynamic performance to enhance user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a structural schematic diagram of a range hood provided in Embodiment 1 of the present invention;

[0026] Figure 2 is a cross-sectional view of a range hood provided in Embodiment 1 of the present invention;

[0027] Figure 3 is a cross-sectional view of an ejection system provided in Embodiment 1 of the present invention;

[0028] Figure 4 The structure of the axial flow fan provided by the first embodiment of the present invention is shown in FIG. Figure 1 ;

[0029] Figure 5 yes Figure 3 A partial enlarged view of the middle A;

[0030] Figure 6 The structure of the axial flow fan provided by the first embodiment of the present invention is shown in FIG. Figure 2 ;

[0031] Figure 7 is a cross-sectional view of an ejection system provided in Embodiment 2 of the present invention;

[0032] Figure 8 yes Figure 7 A partial enlarged view of point B in the middle;

[0033] Fig. 9 is a cross-sectional view of an ejection system provided in Embodiment 3 of the present invention;

[0034] Fig.10 yes Fig. 9 A partial enlarged view of point C in the middle.

[0035] In the figure:

[0036] 1. Mainframe box; 2. Smoke hood; 3. Axial flow fan; 4. Injection fan;

[0037] 21. Main smoke inlet; 22. Auxiliary smoke inlet; 31. Rectification air duct; 32. Moving blade assembly; 33. Stationary blade assembly; 41. Injection air outlet; 42. Air inlet section; 43. Throat section; 44. Air outlet section;

[0038] 311, noise reduction groove; 312, bottom surface; 313, wave section; 314, annular protrusion; 315, annular groove; 321, moving impeller; 322, fairing; 331, stationary impeller; 332, guide cover;

[0039] 3211, moving blades; 3212, moving hub; 3311, stationary blades; 3312, stationary hub. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0041] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0042] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0044] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0045] Embodiment 1

[0046] The fan system of the range hood includes centrifugal fan system and axial flow fan system. The centrifugal fan system is relatively complex, with a large structure and high application cost. The axial flow fan system can be designed to be more compact, which can realize miniaturization of products and more flexible installation and appearance design in a kitchen environment with limited space.

[0047] like Figure 1 As shown, this embodiment provides a range hood, which includes a main body case 1, a smoke hood 2 and an ejection system. The main body case 1 is connected to the smoke hood 2, the ejection system is arranged in the main body case 1, and the smoke hood 2 is provided with a smoke inlet. When the ejection system is started, the smoke can be sucked in through the smoke inlet.

[0048] like Figure 2 and Figure 3 As shown, the induced emission system includes an axial flow fan 3 and an induced emission air cylinder 4, and the axial flow fan 3 is arranged in the induced emission air cylinder 4. When the axial flow fan 3 is started, the oil smoke under the fume hood 2 can pass through the axial flow fan 3 and enter the external flue through the induced emission air cylinder 4, thereby improving the oil smoke condition in the kitchen.

[0049] like Figure 2 to Figure 4 As shown, the axial flow fan 3 includes a rectifying air cylinder 31 and a moving blade assembly 32, the moving blade assembly 32 includes a moving impeller 321, the moving impeller 321 includes a plurality of moving blades 3211 arranged at intervals along the circumferential direction, the moving impeller 321 is rotatably arranged in the rectifying air cylinder 31, the rectifying air cylinder 31 is arranged in the induced air cylinder 4 and is spaced from the inner wall of the induced air cylinder 4, the gap between the rectifying air cylinder 31 and the induced air cylinder 4 forms an induced air port 41, the smoke inlet includes a main smoke inlet 21 and an auxiliary smoke inlet 22, wherein the main smoke inlet 21 is connected to the rectifying air cylinder 31, and the auxiliary smoke inlet 22 is connected to the induced air port 41.

[0050] When the axial flow fan 3 is started, negative pressure is formed at the main smoke inlet 21 to suck in the oil smoke. At the same time, since the axial flow fan 3 causes air to flow along the axial direction of the induced air tube 4, negative pressure is also formed in the induced air tube 4, so that the auxiliary smoke inlet 22 can also play a role in sucking oil smoke. This structure increases the range of the smoke inlet of the range hood, increases the effective air volume, and improves the effect of sucking oil smoke.

[0051] Preferably, the smoke collecting hood 2 is provided with two auxiliary smoke inlets 22, and the two auxiliary smoke inlets 22 are located on the left and right sides of the main smoke inlet 21. This structure can expand the range of oil smoke absorption to the left and right sides of the smoke collecting hood 2, form an effective negative pressure traction for cooking oil smoke, and effectively improve the smoke extraction effect of the range hood.

[0052] like Figure 3As shown, along the axial direction of the induced air cylinder 4, the induced air cylinder 4 includes an air inlet section 42, a throat section 43 and an air outlet section 44 in sequence, the inner diameter of the throat section 43 is smaller than the inner diameter of the air inlet section 42 and the inner diameter of the air outlet section 44, the axial flow fan 3 is arranged in the air inlet section 42, and the outer diameter of the axial flow fan 3 is smaller than the inner diameter of the air inlet section 42. Among them, the induced air port 41 is located between the axial flow fan 3 and the air inlet section 42.

[0053] That is to say, the structure of the ejector 4 is a Venturi tube. According to the Venturi effect, when a fluid passes through a reduced flow cross section, the fluid velocity increases, and the flow velocity is inversely proportional to the flow cross section. According to Bernoulli's principle, the increase in flow velocity is accompanied by a decrease in fluid pressure, so low pressure will be generated near the high-speed flowing fluid, thereby generating an adsorption effect.

[0054] Therefore, in the induced air duct 4 of the present embodiment, when the axial flow fan 3 is started, the gas flows to the throat section 43 after passing through the axial flow fan 3. At this time, the cross-sectional area of ​​the gas flow is reduced, the flow velocity is increased, and the pressure is reduced. Compared with the structure of the straight pipe, this structure will produce a stronger negative pressure area in the throat section 43, thereby attracting more gas from the annular induced air port 41 into the induced air duct 4, thereby achieving the induced flow increase effect.

[0055] This structural design can effectively increase the air volume of the air duct system and maintain a low rotation noise of the axial flow fan 3 without increasing the rotation speed of the axial flow fan 3, thereby increasing the working efficiency of the air duct system.

[0056] It is understandable that the air intake of the induced air port 41 is related not only to the change in the inner diameter of the induced air cylinder 4 and the rotation speed of the axial flow fan 3, but also to the ratio between the rotation radius of the moving blade 3211 of the axial flow fan 3 and the inner wall radius of the air inlet section 42, that is, the ratio of the effective area of ​​the moving blade 3211 when rotating to the cross-sectional area of ​​the air inlet section 42. If the ratio between the rotation radius of the moving blade 3211 and the inner wall radius of the air inlet section 42 is too large, it means that the area of ​​the induced air port 41 is small and the air intake of the induced air port 41 is insufficient; if the ratio between the rotation radius of the moving blade 3211 and the inner wall radius of the air inlet section 42 is too small, it means that the area of ​​the induced air port 41 is large, and the negative pressure of the throat section 43 is dispersed by the larger induced air port 41, resulting in a smaller suction force on the oil smoke.

[0057] like Figure 3 and Figure 5 As shown, in order to make the auxiliary smoke inlet 22 also have sufficient ability to absorb oil smoke, the inner wall radius of the air inlet section 42 is Ri, and the blade tip radius of the moving blade 3211 is Rb, then Specifically, The value of can be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, or 0.7.

[0058] In the prior art, in order to improve the oil fume extraction effect of the range hood, the rotation speed of the axial flow fan 3 is relatively high, which easily leads to technical problems such as high noise, especially the aerodynamic noise easily caused when the airflow flows through the blade tip gap, which affects the user experience.

[0059] like Figure 3 to Figure 5 As shown, in order to solve the above problem, in the axial flow fan 3 provided in this embodiment, a noise reduction groove 311 penetrating along the circumferential direction is opened on the inner wall of the rectifying air cylinder 31 , and the blade tops of multiple moving blades 3211 are located in the noise reduction groove 311 .

[0060] The inner wall of the rectifying air cylinder 31 of the axial flow fan 3 is provided with a noise reduction groove 311. When the impeller 321 rotates, since the blade top of the movable blade 3211 is located in the noise reduction groove 311, the high-speed airflow flowing along the inner side of the rectifying air cylinder 31 will not directly pass through the blade tip gap of the movable blade 3211 (the gap between the blade tip of the movable blade 3211 and the noise reduction groove 311), so the airflow speed between the blade tip of the movable blade 3211 and the inner wall of the rectifying air cylinder 31 is low, which reduces the noise in the turbulent area of ​​the blade tip gap. Moreover, the setting of the noise reduction groove 311 can also reduce the disturbance of the turbulent flow in the mainstream area caused by the change of flow velocity and direction through the blade tip gap, thereby effectively improving the aerodynamic performance of the axial flow fan 3.

[0061] The axial flow fan 3 can reduce noise and improve aerodynamic performance to enhance user experience.

[0062] like Figure 5 As shown, the noise reduction groove 311 includes a bottom surface 312, and the noise reduction groove 311 is an annular groove, the opening of which faces the axis of the rectifying air cylinder 31, and the bottom surface 312 is a surface away from the opening of the annular groove along the radial direction of the rectifying air cylinder 31. Along the radial direction of the rectifying air cylinder 31, the rotation radius of the bottom surface 312 is Rs, and the rotation radius of the inner wall of the rectifying air cylinder 31 is Rc, then Rs>Rb>Rc, indicating that the blade tip of the moving blade 3211 is located in the noise reduction groove 311 and is spaced from the bottom surface 312, 150mm≥Rb≥75mm, which is a limit on the size of the moving blade 3211. If it is too small, the aerodynamic performance of the axial flow fan 3 will be reduced, and if it is too large, the volume will be too large, affecting the appearance size of the range hood. Specifically, the blade tip radius Rb of the moving blade 3211 can be 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm or 150mm.

[0063] Furthermore, the distance between the blade tip and the bottom surface 312 is δ = Rs-Rb, and the depth of the blade tip entering the noise reduction groove 311 is λ = Rb-Rc, then That is to say, the distance between the blade tip and the bottom surface 312 is greater than or equal to the depth of the blade tip entering the noise reduction groove 311, and the noise reduction groove 311 should not be too deep to avoid affecting the effective area of ​​the moving blade 3211 and reducing the aerodynamic performance of the axial flow fan 3. as well as The values ​​of can all be 0.01, 0.02, 0.03, 0.04 or 0.05.

[0064] like Figure 3 and Figure 4 As shown, the impeller 321 includes a moving hub 3212 and a driving motor, the moving hub 3212 is drivingly connected to the driving motor, and a plurality of moving blades 3211 are circumferentially spaced apart on the moving hub 3212. Along the rotation direction of the moving blades 3211, the moving blades 3211 are inclined so that the impeller 321 can drive the gas to flow along the axial direction of the rectifying air cylinder 31.

[0065] In this embodiment, the characteristic cross-section of the moving blade 3211 at any blade height is an airfoil shape, so as to reduce the air resistance encountered by the moving blade 3211 when rotating and reduce energy consumption.

[0066] In this embodiment, the blade space shape after stacking is a curved and swept design, that is, the tip section position of the moving blade 3211 is always on the front side of the blade root section position along the rotation circumference. The curved and swept blade structure design can effectively suppress the end wall boundary layer separation, improve the flow structure in the blade tip area, thereby improving the aerodynamic performance and effectively controlling the aerodynamic noise.

[0067] In this embodiment, a fairing 322 is provided on one side of the moving hub 3212 located at the air inlet end of the fairing air cylinder 31. The fairing 322 is spherical to guide the gas facing the moving hub 3212 to the position of the moving blades 3211, thereby reducing the flow resistance of the gas and improving the aerodynamic performance.

[0068] It is understandable that when the size of the public flue is small or there are many range hoods working at the same time on the same floor, the resistance in the public flue is very large, thus affecting the exhaust effect of the range hoods in the user's home. Figure 3 and Figure 6 As shown, in order to solve the above problems, the axial flow fan 3 also includes a stator blade assembly 33, the stator blade assembly 33 includes a stator impeller 331, the stator impeller 331 includes a plurality of stator blades 3311 arranged at intervals along the circumferential direction, the plurality of stator blades 3311 are all connected to the inner wall of the rectifying air duct 31, and the stator impeller 331 is configured to decelerate the airflow passing through the moving impeller 321.

[0069] The gas accelerated by the moving impeller 321 will be slowed down by the stationary impeller 331, thereby converting kinetic energy into pressure energy to improve the pressure-boosting capacity of the axial flow fan 3, increase the pressure of the gas entering the induced air duct 4, and ensure that the oil smoke can be discharged into the public flue.

[0070] In this embodiment, the stationary impeller 331 further includes a stationary hub 3312, and a plurality of stationary blades 3311 are arranged on the stationary hub 3312 at intervals along the circumferential direction, and along the rotation direction of the moving blades 3211, the inclination direction of the stationary blades 3311 is opposite to the inclination direction of the moving blades 3211. In this structure, after passing through the moving blades 3211, the gas will flow along the axial direction of the rectifying air cylinder 31, and at the same time rotate around the axis of the rectifying air cylinder 31, and the rotation direction is the same as the rotation direction of the moving blades 3211. At this time, when the gas passes through the stationary blades 3311, it will be decelerated by the stationary blades 3311, thereby converting kinetic energy into pressure energy.

[0071] In this embodiment, the stationary impeller 331 also includes a guide cover 332, which is arranged on one side of the stationary hub 3312 located at the air outlet end of the rectifier air duct 31. The guide cover 332 is spherical to guide the gas passing through the stationary impeller 331 to the axial position of the rectifier air duct 31, thereby increasing the flow area and increasing the air volume.

[0072] In this embodiment, the moving blade assembly 32 is arranged on the stationary blade assembly 33. Since the stationary blade assembly 33 remains stationary relative to the rectifier air duct 31, the stationary blade assembly 33 is used as a bracket for installing the moving blade assembly 32, which can simplify the structure and reduce costs.

[0073] Furthermore, the stationary blades 3311, the stationary hub 3312 and the rectifying air cylinder 31 are integrally formed. Specifically, the integral forming process is to form an integrated component through an integral injection molding process so as to have better structural strength and rigidity, and support the moving blade assembly 32 to rotate stably at high speed.

[0074] Embodiment 2

[0075] This embodiment improves the bottom surface 312 of the noise reduction groove 311 on the basis of the first embodiment.

[0076] like Figure 7 and Figure 8 As shown, along the axial direction of the rectifying air cylinder 31, the bottom surface 312 is alternately provided with annular protrusions 314 and annular grooves 315. The structure of the annular protrusions 314 and the annular grooves 315 can suppress the turbulent diffusion at the blade tip gap, form an axially non-uniform space in the blade tip gap through the wavy curved surface structure, suppress the development of secondary flow inside the region and the aggregation and diffusion of low-energy fluid on the end wall, improve the flow structure, thereby achieving the purpose of improving the aerodynamic performance, and can significantly improve the aerodynamic noise of the axial flow fan 3.

[0077] In some embodiments, the annular protrusion 314 and the annular groove 315 are both arcs, and the radius of the arc is Rt. Since the annular protrusion 314 and the annular groove 315 are symmetrical with respect to the original bottom surface 312, the average distance δ' between the blade tip and the bottom surface 312 is Rs-Rb, then

[0078] Understandably, Indicates the degree of proximity between the annular protrusion 314 and the blade tip. The larger the ratio, the closer the annular protrusion 314 is to the blade tip, that is, the greater the fluctuation of the annular protrusion 314 and the annular groove 315 on the bottom surface 312. Although it can effectively suppress the development of secondary flow inside the region and the aggregation and diffusion of low-energy fluid on the end wall, the gas permeability will be affected; the smaller the ratio, the farther the annular protrusion 314 is from the blade tip, that is, the smaller the fluctuation of the annular protrusion 314 and the annular groove 315 on the bottom surface 312. Although the gas permeability is better, it reduces the effect of suppressing the development of secondary flow inside the region and the aggregation and diffusion of low-energy fluid on the end wall. Specifically, The value of can be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5.

[0079] Embodiment 3

[0080] This embodiment improves the bottom surface 312 of the noise reduction groove 311 on the basis of the first embodiment.

[0081] like Fig. 9 and Fig.10 As shown, along the axial direction of the rectifying air duct 31, the bottom surface 312 has a wave section 313, and the cross-sectional figure of the surface of the wave section 313 along the radial direction of the rectifying air duct 31 is a sine curve, and satisfies the sine curve equation y=h*sin(k*x), x∈[0,2π]. This structure can also make the annular protrusion 314 and the annular groove 315 symmetrical relative to the original bottom surface. Among them, x represents a specific point along the axial direction of the rectifying air duct 31, y represents the offset of the point compared with the original bottom surface 312, h is the amplitude of the sine curve, that is, the difference between the maximum offset of the protrusion and the recess of the wave section 313, and k represents the angular frequency of the sine curve, that is, the axial repetition period.

[0082] Furthermore, in the sinusoidal curve equation, It indicates the fluctuation degree of the wave segment 313 when it moves from the crest to the trough. The smaller the ratio is, the greater the fluctuation degree is. The larger the ratio is, the smaller the fluctuation degree is, and the wave segment 313 is closer to being flat. Specifically, It can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4.

[0083] Optionally, the average distance δ" between the blade tip and the bottom surface 312 = Rs-Rb, then It indicates the degree of proximity between the crest of the wave segment 313 and the blade top. The larger the ratio is, the closer the crest of the wave segment 313 is to the blade top, that is, the greater the fluctuation of the wave segment 313 on the bottom surface 312 is. Although it can effectively suppress the development of secondary flow inside the region and the aggregation and diffusion of low-energy fluid on the end wall, the gas permeability will be affected. The smaller the ratio is, the farther the crest of the wave segment 313 is from the blade top, that is, the smaller the fluctuation of the wave segment 313 on the bottom surface 312 is. Although the gas permeability is better, the effect of suppressing the development of secondary flow inside the region and the aggregation and diffusion of low-energy fluid on the end wall is reduced.

[0084] Specifically, The value of can be 0.1, 0.15, 0.2, or 0.25.

[0085] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there will be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims

1. An axial flow fan, characterized in that: include: A rectifying air cylinder (31), wherein the inner wall of the rectifying air cylinder (31) is provided with a noise reduction groove (311) penetrating in the circumferential direction; A moving blade assembly (32), the moving blade assembly (32) comprising a moving impeller (321), the moving impeller (321) being rotatably disposed in the rectifying air cylinder (31), the moving impeller (321) comprising a plurality of moving blades (3211) spaced apart in a circumferential direction, the blade tops of the plurality of moving blades (3211) being located in the noise reduction groove (311).

2. The axial flow fan according to claim 1, characterized in that: The noise reduction groove (311) comprises a bottom surface (312), and along the radial direction of the rectifying air cylinder (31), the rotation radius of the bottom surface (312) is Rs, the rotation radius of the inner wall of the rectifying air cylinder (31) is Rc, and the blade tip radius of the moving blade (3211) is Rb, then Rs>Rb>Rc.

3. The axial flow fan according to claim 2, characterized in that: The distance δ between the blade tip and the bottom surface (312) is Rs-Rb, and the depth λ of the blade tip entering the noise reduction groove (311) is Rb-Rc.

4. The axial flow fan according to claim 2, characterized in that: Along the axial direction of the rectifying air cylinder (31), the bottom surface (312) is alternately provided with annular protrusions (314) and annular grooves (315).

5. The axial flow fan according to claim 4, characterized in that: The annular protrusion (314) and the annular groove (315) are both circular arcs, and the radius of the circular arc is Rt. The average distance δ' between the blade tip and the bottom surface (312) is Rs-Rb. Then 6. The axial flow fan according to claim 2, characterized in that: Along the axial direction of the rectifying air cylinder (31), the bottom surface (312) has a wave section (313), and the cross-sectional figure of the surface of the wave section (313) along the radial direction of the rectifying air cylinder (31) is a sine curve and satisfies the sine curve equation y=h*sin(k*x), x∈[0,2π].

7. The axial flow fan according to claim 6, characterized in that: In the sinusoidal equation, 8. The axial flow fan according to claim 6, characterized in that: The average distance δ" between the blade tip and the bottom surface (312) = Rs-Rb, then 9. The axial flow fan according to any one of claims 1 to 8, characterized in that: The axial flow fan also includes a stationary blade assembly (33), the stationary blade assembly (33) includes a stationary impeller (331), the stationary impeller (331) includes a plurality of stationary blades (3311) arranged at intervals along the circumferential direction, the plurality of stationary blades (3311) are all connected to the inner wall of the rectifying air cylinder (31), and the stationary impeller (331) is configured to decelerate the airflow passing through the moving impeller (321).

10. The axial flow fan according to claim 9, characterized in that: The moving blade assembly (32) is arranged on the stationary blade assembly (33).

11. An ejection system, characterized in that: The induced jet system comprises the axial flow fan according to any one of claims 1 to 10, and also comprises an induced jet wind cylinder (4), wherein the axial flow fan (3) is arranged in the induced jet wind cylinder (4).

12. The ejection system according to claim 11, characterized in that: Along the axial direction of the induced air cylinder (4), the induced air cylinder (4) comprises an air inlet section (42), a throat section (43) and an air outlet section (44) in sequence, the inner diameter of the throat section (43) being smaller than the inner diameter of the air inlet section (42) and the inner diameter of the air outlet section (44), the axial flow fan (3) being arranged in the air inlet section (42), and the outer diameter of the axial flow fan (3) being smaller than the inner diameter of the air inlet section (42).

13. The ejection system according to claim 12, characterized in that: The inner wall radius of the air inlet section (42) is Ri, and the tip radius of the moving blade (3211) is Rb, then 14. A range hood, characterized in that: The range hood comprises the educing system according to any one of claims 11 to 13.

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