Impeller assembly for centrifugal fan, centrifugal fan and range hood

Abstract

The invention relates to an impeller assembly for a centrifugal fan, the centrifugal fan and a range hood. The impeller assembly comprises a first disc and a second disc which are oppositely arranged in the front-back direction; each blade is further provided with a front edge corresponding to the air inlet side and a tail edge corresponding to the air outlet side; a front wave-shaped section is arranged at the position, close to the first disc, of the front edge of the blade, a rear wave-shaped section is arranged at the position, close to the first disc, of the tail edge of the blade, and the maximum wavelength of the front wave-shaped section is smaller than or equal to the minimum wavelength of the rear wave-shaped section. The blade has the advantages that the maximum wavelength of the front wave-shaped section, close to the air inlet, of the front edge of the blade is limited to be smaller than or equal to the minimum wavelength of the rear wave-shaped section at the corresponding position of the tail edge, and the synergistic effect of front and tail edge wave-shaped structures is achieved. The small wavelength of the front edge effectively breaks inlet vortexes, and flow separation is restrained; and the relatively large wavelength of the trailing edge reduces dynamic and static interference with the volute by regulating and controlling the outlet vortex shedding frequency, and meanwhile, weakening of the power capability due to excessive shortening of a flow channel is avoided.

Description

Technical Field

[0001] This invention relates to the field of range hood technology, and in particular to an impeller assembly for a centrifugal fan, a centrifugal fan, and a range hood. Background Technology

[0002] A range hood is a kitchen appliance used to purify the kitchen environment. The centrifugal fan is a key component of a range hood. A centrifugal fan generally consists of a volute, an impeller rotating within the volute, and a motor that drives the impeller. Existing centrifugal fan impellers typically have blades that are straight, single-arc sheet metal structures, meaning their planar unfolded shape is basically rectangular. Due to the characteristics of centrifugal fans, the airflow undergoes multiple bends and changes of direction during its flow, resulting in vortex phenomena caused by flow separation at both ends of the impeller, and also dynamic and static interference with the volute. Existing patents include those that use airfoil designs on blades to reduce flow separation, but these airfoil blades are generally thicker, which reduces the impeller's work capacity. For example, patent application CN202220333700.2 discloses a similar method for impellers, centrifugal fans, and range hoods. Other patents disclose methods for breaking eddies and reducing noise by independently setting equidistant or proportionally varying waves on the leading or trailing edge of the blades. For example, patent application CN202010739577.X discloses a similar method for blades used in centrifugal fans, centrifugal fans, and range hoods.

[0003] However, current impellers employ toothed or wave-shaped noise reduction designs on their leading and trailing edges, primarily for improving vortex breaking at the leading and trailing edges. These designs typically incorporate toothed or wave-shaped structures throughout the entire impeller section, without considering the simultaneous existence of corresponding noise reduction structures at both the leading and trailing edges. Poor coupling between these structures can lead to mutual interference, preventing them from achieving their intended effect. For example, while toothed leading edges may disrupt the vortex structure at the leading edge and reduce vortex intensity, an unreasonable toothed design at the trailing edge can reduce the blade flow channel length, resulting in a significant decrease in work capacity. Conversely, the absence of toothed trailing edges prevents the effective alteration of the shedding vortex frequency and reduction of dynamic and static interference with the volute. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is to provide an impeller assembly for centrifugal fans that addresses the current state of the technology, thereby solving the problems of weakened work capacity, vortex re-aggregation, increased pressure pulsation, and poor backflow control caused by the independent dimensional design or layout of the leading and trailing edges of the blades, thus effectively improving aerodynamic performance and reducing noise.

[0005] The second technical problem to be solved by the present invention is to provide a centrifugal fan that uses the above-mentioned impeller assembly, in view of the current state of the prior art.

[0006] The third technical problem to be solved by the present invention is to provide a range hood that uses the above-mentioned centrifugal fan, in view of the current state of the prior art.

[0007] The technical solution adopted by the present invention to solve the first technical problem is: an impeller assembly for a centrifugal fan, comprising: a first disc and a second disc arranged opposite to each other in the front-back direction, the first disc being located at the air inlet of the fan; and a plurality of blades arranged between the first disc and the second disc and along the circumferential direction, each blade also having a leading edge corresponding to the air inlet side and a trailing edge corresponding to the air outlet side.

[0008] A front wave segment is provided at the leading edge of the blade near the first disk, and a rear wave segment is provided at the trailing edge of the blade near the first disk. The maximum wavelength of the front wave segment is less than or equal to the minimum wavelength of the rear wave segment.

[0009] The leading edge of the blade primarily functions to break up vortices in the non-mainstream airflow at the impeller inlet. Generally, a smaller wavelength is required to achieve a better vortex-breaking effect. However, the trailing edge of the blade is influenced by the leading edge. If the size is smaller than the leading edge, the small-scale vortices broken up at the leading edge cannot form an effective staggered outflow at the impeller outlet, thus failing to achieve an effective noise reduction effect. Therefore, the maximum wavelength of the leading edge of the blade should be less than or equal to the minimum wavelength of the trailing edge of the blade. To further ensure the noise reduction effect, in the preferred embodiment, the maximum wavelength of the leading edge of the blade should be less than the minimum wavelength of the trailing edge of the blade.

[0010] Furthermore, the leading edge of the blade also includes a front main straight segment connected to the front wave segment and located away from the front disk, and at least a portion of the rear wave segment is opposite to at least a portion of the front main straight segment in the width direction of the blade.

[0011] The leading straight section of the blade's leading edge mainly corresponds to the impeller's main flow area, i.e., the main power-generating area. This area is generally quite long. If the trailing wave section of the trailing edge is not opposite to this leading straight section at all, it will result in a shorter trailing wave section of the trailing edge, weakening the noise reduction effect. In addition, the airflow enters the blade passage obliquely, and the breaking vortex at the end of the leading wave section of the blade's leading edge (which is also the starting point of the leading straight section) shifts axially towards the second disk. The presence of the trailing wave section in this area has a relatively small impact on the power generation. Therefore, in the preferred embodiment, at least a portion of the trailing wave section is opposite to at least a portion of the leading straight section in the blade width direction.

[0012] As an improvement, the trailing wave segment on the trailing edge of the blade includes a first wave segment and a second wave segment arranged sequentially from the end near the first disk to the end away from the first disk. At least a portion of the first wave segment is opposite to at least a portion of the leading wave segment of the blade's leading edge in the blade width direction; the second wave segment is opposite to a portion of the leading main straight segment of the blade's leading edge in the blade width direction.

[0013] As an improvement, the starting point of the first waveform segment is closer to the first disk than the connection point between the previous waveform segment and the previous main straight line segment, and the maximum wavelength of the first waveform segment is less than or equal to the minimum wavelength of the second waveform segment.

[0014] Further improvements can be made to allow the first and second waveform segments to have equidistant waveforms or waveforms with progressively increasing wavelengths along the blade length.

[0015] The airflow is not uniformly distributed along the axial direction. Generally, the airflow velocity is higher towards the second disk. Appropriately increasing the wavelength can reduce the impact on the work done by the blades. If noise reduction is the main consideration, an equidistant design can also be used, appropriately sacrificing work performance.

[0016] Furthermore, the region where the first waveform segment is located is the non-mainstream working area of ​​the blade. Therefore, a short-wavelength waveform design should be used at the corresponding trailing edge of the blade to reduce the intensity of secondary backflow in the reverse vortex core region. For this reason, the wavelength S of the first waveform segment... 21 and wave height N 21 The two dimensions are defined as follows: the wavelength of the first waveform segment satisfies the following condition:

[0017] β is the impeller outlet angle, and the value range of β is: 150°≤β≤180°;

[0018] The wave height of the first waveform segment is denoted as N. 21 And it meets the following conditions:

[0019] 0.01sinβL≤N 21 ≤0.15sinβL; where L is the width of the blade after it is flattened;

[0020] The second waveform segment is located in the impeller's main flow region and should ideally be set to a wide wavelength waveform. This alters the trailing edge vortex shedding frequency and improves pressure pulsation on the blade surface, thereby reducing aerodynamic noise during impeller operation and enhancing aerodynamic efficiency. Specifically, the wavelength of the second waveform segment is denoted as S. 22 S 22 Condition S is satisfied. 21 <S 22 ≤5S 21 ;

[0021] The wave height of the second waveform segment is denoted as N. 22 N 22 Condition: 0.05L≤N 22 ≤0.2L.

[0022] As an improvement, both the first and second waveform segments are constructed as waveform curves with concave and convex portions arranged in sequence, wherein the concave or convex portions of the waveform curves are configured as tooth-shaped, arc-shaped, or airfoil-shaped structures.

[0023] As an improvement, the wavelengths of any two adjacent bands in the first waveform segment are respectively denoted as S21. i and S21 i+1 The wave heights are denoted as N21. i and N21 i+1 ;

[0024] The wavelengths and wave heights of any two adjacent bands in the first waveform segment satisfy the following conditions:

[0025] S21 i <S21 i+1 ≤1.3S21 i ;

[0026] 0.8N21 i ≤N21 i+1 <N21 i ;

[0027] The wavelengths of any two adjacent bands in the second waveform segment are denoted as S22. i and S22 i+1 The wave heights are denoted as N22. i and N22 i+1 ;

[0028] The wavelength and wave height of any two adjacent bands in the second waveform segment satisfy the following condition:

[0029] S22 i <S22 i+1 ≤1.3S22 i ;

[0030] 0.8N22 i ≤N22 i+1 <N22 i .

[0031] Furthermore, the wavelength of the preceding waveform segment increases sequentially along the blade length.

[0032] Furthermore, the wave corresponding to the leading edge waveform segment of the blade has two dimensions: wavelength and wave height. The impact of the leading edge of the multi-blade centrifugal fan blade is related to the impeller inlet impact angle. Establishing a waveform dimension design relationship based on the impact angle can better match the characteristics of the multi-blade centrifugal fan. The established waveform dimension relationship is related to the waveform segment length, not directly related to the blade depth, thereby ensuring the number of waveforms. Specifically, the wavelength of the leading edge waveform segment is denoted as S1, and S1 satisfies the following condition:

[0033] And α∈[30°, 90°];

[0034] Where α is the impeller inlet angle. The larger the inlet angle, the greater the impact, and the smaller the waveform segment is required to break the vortex.

[0035] H2 is the length of the front wave segment along the axis of the impeller.

[0036] As an improvement, the wave height of the preceding waveform segment is denoted as N1, and satisfies the following condition:

[0037] 0.1sin(α)L≤N1≤0.4sin(α)L; L is the width dimension of the blade after it is flattened.

[0038] As an improvement, the wavelengths of any two adjacent bands in the preceding waveform segment are denoted as Sl. i and Sl i+1 The wave heights are denoted as Nl. i and Nl i+1 ;

[0039] The wavelength and wave height of any two adjacent bands in the preceding waveform segment satisfy the following condition:

[0040] Sl i <Sl i+1 ≤1.3Sl i ;

[0041] 0.8Nl i ≤Nl i+1 <Nl i .

[0042] Furthermore, a section of the impeller blades near the first or second disk is a non-working zone, primarily characterized by recirculation, i.e., the airflow direction is from the blade outlet to the inlet. Adding a waveform structure would actually reduce the blade passage size, and a longer blade passage size helps suppress recirculation towards the inlet side; therefore, no waveform structure is provided. The leading edges of the two blade segments also include a front auxiliary straight section positioned closer to the first disk than the front waveform section. The extension direction of the front auxiliary straight section is parallel to or at an angle to the impeller axis. The front auxiliary straight section and a portion of the rear waveform section are opposite each other in the blade width direction. A portion of the rear waveform section opposite the aforementioned front auxiliary straight section in the blade width direction also corresponds to the blade tip recirculation zone, so a short-wavelength waveform design is used to reduce the intensity of secondary recirculation in the reverse vortex core region.

[0043] The "width direction" of the blades in this application is generally a direction perpendicular to the impeller axis, usually corresponding to the chord length direction of the blade, that is, the direction from the leading edge to the trailing edge of the blade.

[0044] The technical solution adopted by the present invention to solve the second technical problem is as follows: the centrifugal fan includes a volute, and a collector is provided at the air inlet of the volute;

[0045] The length of the preceding wave segment along the impeller axis is denoted as H2, and satisfies the following condition: And 0.8D n ≤D1≤D n 0.5≤H z / H q ≤2; where D1 is the maximum diameter of the collector inlet. The maximum diameter can be understood as follows: if the collector inlet is a non-circular, irregularly shaped inlet, the maximum diameter of the collector inlet should be the maximum distance between two points on the collector's perimeter profile passing through the collector's center; if the collector inlet is circular, then it is the inlet diameter; D n H is the minimum inner diameter of the impeller, which is also the minimum diameter formed by the leading edge of the blade in the radial direction; z The impeller axial depth is defined as follows, depending on whether the fan has a single or double inlet: For a single inlet fan, the first disc mentioned above is the front disc, and the second disc mentioned above is the rear disc, then H... z This refers to the distance between the front and rear discs of the impeller (i.e., the distance between the first and second discs). For a dual-inlet centrifugal fan, the first disc is either the front or rear disc, and the second disc is the middle disc. The H mentioned... z This refers to the axial depth on one side, which is the distance from the front or rear disc of the impeller to the middle disc (i.e., the distance from the first disc to the second disc); H q The depth of the air intake space on the front or rear side of the centrifugal fan inside the casing is taken as the distance from the side wall of the volute corresponding to the air inlet to the inner wall of the front casing. If there are other components such as sound-absorbing boxes on the inner wall of the casing, it is the distance from the outer surface of the volute to the surface of other components on the inner wall of the front casing. When H q When the thickness is not uniform, the arithmetic mean distance H is used. qc , Area element A is generally taken as the effective ventilation area enclosed by the air inlet of the collector; range hoods are limited by installation conditions such as cabinet depth, therefore, H q It should not be too large, generally not exceeding H z Twice as much, H q The diameter should not be too small, otherwise the space on the first air intake side will be too small, resulting in poor air intake. Since both the ratio of the collector to the impeller inner diameter and the ratio of the air intake space in front of the fan to the corresponding impeller depth affect the flow at the impeller leading edge, the depth of the waveform segment needs to be considered based on the dimension with the greater influence.

[0046] Centrifugal fans are divided into single-inlet fans and double-inlet fans. For a single-inlet fan, the axial length of the blades refers to the length of the blades between the front disc and the middle disc. For a double-inlet fan, the blades are divided into two segments, front and rear, with the middle disc as the boundary. At least one of the two blade segments includes the wave-shaped segment at its leading edge. The axial length of the blades refers to the length of the blades on one side, that is, the length of the blades between the front or rear disc and the middle disc.

[0047] Centrifugal fans, in practical applications (such as range hoods), are limited by factors such as the size of the machine casing (i.e., the air box) and the air intake conditions of the collector. The flow separation and backflow phenomena at the impeller blade leading edge are closely related to the flow guiding design of the casing and collector. Therefore, the length of the leading edge wave section of the blade in the impeller axial direction is neither better the longer nor the shorter the better. This invention addresses this by adjusting the axial length H2 of the leading edge wave section of the blade in relation to the collector inlet diameter D1 and the impeller inner diameter D... n The depth dimension H of the impeller on one side Z And the depth H of the air intake space on this side. q By coordinating the design of multiple parameters, the waveform of the blades can be matched to different air intake conditions, thereby effectively reducing airflow noise while ensuring that the aerodynamic performance of the fan is not significantly affected.

[0048] As an improvement, the leading edge of the blade also includes a front auxiliary straight segment that is positioned closer to the first disk than the leading wave segment. The length H1 of the front auxiliary straight segment of the blade in the axial direction of the impeller satisfies the following condition:

[0049] 0 < H1 < 0.2(5H0 + H) z )*H z / H q Where H0 is the distance from the first disc of the impeller to the front or rear cover plate of the volute, H0∈(0,30]mm;

[0050] The section of the impeller blades near the first disc is a non-operating zone, primarily for recirculation. This means the airflow direction is from the blade outlet to the inlet. Adding a wave-like structure to the blade leading edge would actually reduce the blade passage size. A longer blade passage helps suppress recirculation towards the inlet side; therefore, no wave-like structure is used. The blade leading edge also includes a first non-wave-like section (preferably a straight section, or secondary straight section) positioned closer to the first disc than the preceding wave-like section. This is because the airflow from the (top-mounted fan) box (i.e., the fan frame) into the impeller needs to make a large-angle turn. z / H qThe larger the value, the sharper the turn, and the more severe the backflow after entering the impeller. Of course, in some operating conditions, such as when the backflow zone on the front side of the impeller is not obvious, the first non-waveform segment may not be set. If experiments or simulations show that the backflow zone on the front side of the impeller is not obvious, H1 can be set to 0, that is, the front straight segment is not set.

[0051] As an improvement, the blade further includes a front main straight section away from the first disk; the length of the front main straight section in the axial direction of the impeller is denoted as H3, where 0.5 (H z -H1-H2)≤H3≤(H Z -H1-H2); The trailing edge of the impeller also includes a rear straight section disposed adjacent to the second disk, a portion of the front main straight section is opposite to the rear straight section in the width direction of the blade, and a portion of the front main straight section is also opposite to a portion of the rear wave section in the width direction of the blade.

[0052] As mentioned earlier, the front straight section is the main airflow area at the inlet leading edge, where the airflow is relatively stable and there are relatively few large-scale vortices. Therefore, there is no need to set a waveform section. However, in order to balance the noise reduction effect and the fan performance, it is necessary to further design the length of the waveform section and the straight section.

[0053] As an improvement, the length of the rear waveform segment along the impeller axis is denoted as H. 20 H 20 The following conditions must be met: And 0.8D n ≤D1≤D n 0.5≤H z / H q ≤2, 0.05H Z ≤H4≤0.3H Z Where H4 is the length of the straight section of the trailing edge; considering that the increase in blade length in the mainstream region of the impeller due to the straight section of the trailing edge can enhance work capacity to some extent, it will weaken the noise reduction effect. Therefore, the length of the straight section of the trailing edge should not be too long. At the same time, the length of the straight section of the trailing edge should meet the installation requirements. Specifically, the length of the straight section in the axial direction of the impeller needs to meet 0.05H. Z ≤H4≤0.3H Z .

[0054] The technical solution adopted by the present invention to solve the third technical problem is: a range hood, including a housing and a centrifugal fan disposed in the housing, wherein the centrifugal fan is the centrifugal fan described above.

[0055] Compared with existing technologies, the advantages of this invention are as follows: This application addresses the problem of poor coupling and independent design of existing impeller leading and trailing edge noise reduction structures. By limiting the maximum wavelength of the leading edge waveform segment near the air inlet to be less than or equal to the minimum wavelength of the trailing edge waveform segment at the corresponding position, a synergistic effect of the leading and trailing edge waveform structures is achieved. The smaller wavelength at the leading edge effectively breaks up the inlet vortex and suppresses flow separation; the larger wavelength at the trailing edge, by adjusting the outlet vortex shedding frequency, reduces dynamic and static interference with the volute, while avoiding excessive shortening of the flow channel and weakening work capacity. This synergistic design balances leading edge vortex breaking and trailing edge noise reduction, significantly reducing vortex regeneration and pressure pulsation, improving airflow organization stability and aerodynamic efficiency, and ultimately achieving effective noise optimization while ensuring wind pressure performance. In a preferred embodiment, the impeller blade leading edge structure of the present invention adopts a segmented design, including a front main straight section near the central disk and a front wave-shaped section away from the central disk. The extension direction of the front main straight section is parallel to or at an angle to the axis of the impeller. The region of the impeller leading edge near the central disk corresponds to the main flow area at the impeller inlet, where the airflow is relatively stable and there are relatively few large-scale vortices. If a wave-shaped section is set, although it can destroy a small portion of large-scale vortices, the main flow will be disrupted, generating more small-scale vortices. The overall vortex intensity may be greater than the intensity of the original small portion of large-scale vortices. In addition, due to the partial loss of blade material, the work capacity will also be reduced. Therefore, the structural design of setting a front main straight section is adopted. On the other hand, due to the influence of the casing (i.e., the wind box) outside the centrifugal fan, the airflow near the first or second disk side of the centrifugal fan impeller has a large angle of bend, and the airflow has a large impact on the leading edge of the blade. The set front wave-shaped section can break up vortices and reduce noise by breaking large-scale vortices into small-scale vortices, thereby reducing the vortex intensity. The impeller blades of this invention enhance control of the tip recirculation zone through segmented design, reducing the impact on the stable airflow in the main intake zone at the blade leading edge, weakening the impact of blade size on the impeller's work capacity, improving aerodynamic performance, and enhancing noise reduction. Furthermore, the trailing edges of the two blade segments are designed with matching coupling. Each blade trailing edge includes a straight section near the mid-disk and a wave-shaped section away from the mid-disk. The portion of the wave-shaped section is opposite to the front wave-shaped section of the leading edge in the blade's width direction. The straight section at the front edge is opposite to the portion of the wave-shaped section and the straight section at the rear edge in the blade's width direction. By setting the size coupling relationship and matching distribution layout of the leading and trailing edge waveforms from a flow mechanism perspective, problems such as weakened work capacity, vortex re-aggregation, increased pressure pulsation, and poor recirculation control that arise when the leading and trailing edges are designed or laid out independently are solved. This effectively improves aerodynamic performance and achieves the goal of reducing noise. Attached Figure Description

[0056] Figure 1 This is a three-dimensional structural diagram of a range hood according to an embodiment of the present invention;

[0057] Figure 2This is a vertical sectional view of the range hood of the present invention, cut along the front-to-back direction. The centrifugal fan is a dual-inlet fan.

[0058] Figure 3 This is a three-dimensional structural diagram of a centrifugal fan according to an embodiment of the present invention. The centrifugal fan is a dual-inlet fan.

[0059] Figure 4 This is a vertical sectional view of a centrifugal fan cut along the axial direction according to an embodiment of the present invention. The centrifugal fan is a dual-inlet fan.

[0060] Figure 5 This is a three-dimensional structural diagram of the impeller of a centrifugal fan according to an embodiment of the present invention. The centrifugal fan is a double-inlet fan.

[0061] Figure 6 This is a front view of the impeller blades in an embodiment of the present invention; the centrifugal fan is a dual-inlet fan.

[0062] Figure 7 The image shows a vertical sectional view of the range hood in an embodiment of the present invention, with a sound-absorbing box provided on the side wall opposite to the main air inlet of the centrifugal fan.

[0063] Figure 8 This is a vertical sectional view of the range hood of the present invention, cut along the axial direction. The centrifugal fan is a single-inlet fan.

[0064] Figure 9 This is a vertical sectional view of a centrifugal fan according to an embodiment of the present invention, cut along the front-to-back direction. The centrifugal fan is a single-inlet fan.

[0065] Figure 10 This is a front view of the impeller blades in an embodiment of the present invention. The centrifugal fan is a single-inlet fan.

[0066] Figure 11 This is a vertical sectional view of a range hood according to an embodiment of the present invention, cut along the front-to-back direction. The range hood is a different model, and the front side of the range hood of this model has a non-smooth air intake.

[0067] Figure 12 This is a comparison of simulated pressure cloud diagrams of the centrifugal fan in this embodiment of the invention and the prototype (a segmented waveform structure without blade leading and trailing edges). Detailed Implementation

[0068] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0069] The specification and claims of this invention use terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," to describe various exemplary structural parts and elements of the invention. However, these terms are used herein merely for ease of explanation and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0070] Figures 1-12 This illustration shows a preferred embodiment of the impeller assembly for a centrifugal fan, the centrifugal fan, and a range hood according to the present invention. The range hood includes a housing 10 and a centrifugal fan 13 disposed within the housing 10. The housing 10 generally includes a fan frame 11 and a smoke collection hood 12 disposed at the bottom of the fan frame 11, with the inner cavity of the fan frame 11 communicating with the inner cavity of the smoke collection hood 12. An air inlet is provided on the front side wall of the smoke collection hood 12, allowing external smoke to enter the smoke collection hood 12. The centrifugal fan 13 is disposed within the fan frame 11. When the centrifugal fan 13 operates, it generates negative pressure, drawing external fumes into the smoke collection hood 12 through the air inlet. An oil filter is also provided at the air inlet of the smoke collection hood 12 for filtering fumes. An oil cup, which is a long strip extending laterally, is provided at the bottom of the smoke collection hood 12 to collect oil stains flowing down from the smoke collection hood 12. The front of the smoke hood 12 is also provided with a smoke baffle that can deflect back and forth relative to the smoke hood 12. The smoke baffle is connected to the main body of the smoke hood 12 via a hinge mechanism. Specifically, it can deflect forward to open the air inlet and deflect backward to block and close the air inlet. The hinge mechanism used to drive the deflection of the smoke baffle can be a conventional hinge mechanism in the prior art, which will not be described in detail here.

[0071] The centrifugal fan 13 is a key component of the range hood, comprising a volute 20, an impeller 30 rotating within the volute 20, and a motor 35 driving the impeller 30 to rotate. The volute 20 includes a front cover plate 21 and a rear cover plate 22 facing each other, and an annular wall between the front cover plate 21 and the rear cover plate 22. The front cover plate 21 generally has a main air inlet 210, and the rear cover plate 22 has a secondary air inlet 220. The motor 35 is fixed to the secondary air inlet of the volute 20 by a motor 35 bracket, so it will affect the air volume of the air inlet on that side to a certain extent. That is, under normal circumstances, the air volume of the main air inlet 210 is greater than that of the secondary air inlet 220.

[0072] The centrifugal fan of this invention can be either a single-inlet centrifugal fan or a double-inlet centrifugal fan. The difference is that the single-inlet centrifugal fan has no central plate, while the double-inlet centrifugal fan contains a central plate. For example... Figures 1-7A dual-inlet centrifugal fan and a range hood using the dual-inlet centrifugal fan are shown. Figures 8-10 A single-inlet centrifugal fan and a range hood using this single-inlet centrifugal fan are illustrated. It should be further explained that the impeller of a dual-inlet fan is divided into two blade segments, with the central disc as the boundary. At least one blade segment in this invention has a leading-edge wave-shaped section and a trailing-edge wave-shaped section. The first disc mentioned above corresponds to either the front or rear disc of the impeller, and the second disc corresponds to the central disc of the impeller. The impeller design involved is applicable to either side of the blade segment. Since dual-inlet centrifugal fans currently have a wider range of applications, especially in the field of range hoods, this invention mainly uses a dual-inlet centrifugal fan as an example for explanation.

[0073] Specifically, for a dual-inlet fan, the impeller 30 includes two opposing end rings, a central disc 33 located between the two end rings, and multiple blades 34. The two end rings are a front disc 31 and a rear disc 32, which are also known as the first disc, while the central disc is the second disc. Multiple blades 34 are connected between the front disc 31 and the rear disc 32 and are distributed circumferentially. Each blade 34 also has a leading edge 3401 corresponding to the air inlet side and a trailing edge 3402 corresponding to the air outlet side. Each blade 34 is divided into two segments, front and rear, with the central disc 33 as the boundary. The segment corresponding to the front disc 31 is the front blade segment, and the segment corresponding to the rear disc 32 is the rear blade segment. Generally, the central disc 33 is positioned relatively close to the rear disc 32, meaning the length of the front blade segment is usually greater than the length of the rear blade segment.

[0074] Most range hoods employ a top-mounted fan structure, with the centrifugal fan 13 housed within the fan frame 11. The air inlet of the centrifugal fan 13 is not open, and the airflow flows smoothly from bottom to top into the front of the fan inlet before turning at an angle to enter the centrifugal fan 13. In this case, it is necessary to consider the relationship between the segmented impeller noise reduction structure and the dimensions of the collector 211 and the fan inlet housing. In this embodiment, smooth airflow from bottom to top means that there are no structural protrusions obstructing airflow within a certain distance H below the centrifugal fan 13, where H ≥ 0.5H. q H q The depth of the air intake space on the front or rear side of the centrifugal fan 13 within the fan frame 11 of the casing 10, such as... Figure 7 As shown in the diagram; otherwise, it will cause the airflow to change direction multiple times, resulting in airflow turbulence. Figure 11 The range hood shown is a traditional range hood with an unconventional top-mounted fan.

[0075] like Figures 3 to 5As shown, the impeller 30 assembly includes a front disc 31 and a rear disc 32 arranged opposite each other in the front-rear direction, and a middle disc 33 located between the front disc 31 and the rear disc 32. The front disc 31 and the rear disc 32 are located at the front and rear air inlets of the fan, respectively, and the middle disc 33 divides the impeller 30 into two independent blade segments 34, front and rear. Each blade segment 34 includes multiple blades 34 arranged circumferentially.

[0076] The segmented design of the leading edge 3401 of the blade 34 of the impeller 30 assembly of the centrifugal fan 13 in this embodiment is specifically as follows: Figure 5 and Figure 6 As shown, taking one of the blade segments 34 (such as the front blade segment 34) as an example, each blade 34 has a leading edge 3401 on the air inlet side and a trailing edge 3402 on the air outlet side. The leading edge 3401 of the blade 34 adopts a segmented design, from the end near the front plate 31 to the end away from the front plate 31 (i.e., near the middle plate 33), it includes, in sequence: a front auxiliary straight segment 345, a front wave segment 344, and a front main straight segment 343.

[0077] The front straight section 345 is located on the outermost side of blade 34, corresponding to the non-mainstream region (recirculation zone) at the impeller inlet of 30. In this region, there is reverse airflow from the outlet to the inlet; setting a waveform structure would shorten the effective flow path, which would be detrimental to suppressing recirculation. Therefore, this section is designed as a straight line, with its extension direction parallel to the impeller 30 axis. The axial length H1 of this section satisfies: 0 < H1 < 0.2(5H0 + H z )*H z / H q Where H0 is the distance from the first disc of the impeller to the front or rear cover plate of the volute, H0∈(0,30]mm. If the simulation shows that the recirculation zone is not obvious, H1 can be taken as 0, that is, this segment is canceled, and the front waveform segment starts directly from the outermost end of the blade.

[0078] The leading wave section 344 is one of the key areas for vortex breaking and noise reduction. Due to the structure of the casing 10 (windbox), the airflow needs to make a sharp turn before entering the impeller 30, resulting in a significant impact on the outer side of the leading edge 3401 of the blade 34, easily forming large-scale vortices. The leading wave section 344, through its small wavelength structure, breaks large-scale vortices into smaller-scale vortices, effectively reducing vortex intensity and flow separation. Its axial length H2 is a core parameter that must be matched with the overall air intake conditions and meet the following conditions:

[0079] And 0.8Dn≤D1≤Dn, 0.5≤H z / H q ≤2;

[0080] Where D1 is the maximum diameter of the inlet of collector 211. The maximum diameter can be understood as follows: if the inlet of collector 211 is a non-circular irregular inlet, the maximum diameter of the inlet of collector 211 should be the maximum distance between two points on the periphery of collector 211 passing through the center of collector 211; if the inlet of collector 211 is circular, then it is the inlet diameter; D n H is the minimum inner diameter of the impeller 30, which is also the minimum diameter formed by the leading edge 3401 of the blade 34 in the radial direction; z The axial depth of impeller 30 is interpreted as follows, depending on whether the fan has a single or double inlet: For a single inlet fan, the first disc mentioned above is the front disc 31, and the second disc mentioned above is the rear disc 32, then H z This refers to the distance between the front disc 31 and the rear disc 32 of the impeller 30 (i.e., the distance between the first disc and the second disc). For a dual-inlet centrifugal fan 13, the first disc is either the front disc 31 or the rear disc 32, and the second disc is the middle disc 33. The H... z This refers to the axial depth on one side, that is, the distance from the front disc 31 or rear disc 32 of the impeller 30 to the middle disc 33 (i.e., the distance from the first disc to the second disc); H q The depth of the air intake space on the front or rear side of the centrifugal fan 13 inside the housing 10 is taken as the distance from the outer wall surface of the volute 20 corresponding to the air inlet to the inner wall of the front housing 10. If there are other components such as sound-absorbing boxes on the inner wall of the housing 10, it is the distance from the outer surface of the volute 20 to the surface of other components on the inner wall of the front housing 10. When H q When the thickness is not uniform, the arithmetic mean distance H is used. qc , Area element A is generally taken as the effective ventilation area enclosed by the air inlet of the collector 211; range hoods are limited by installation conditions such as cabinet depth, therefore, H q It should not be too large, generally not exceeding H z Twice as much, H q It should not be too small, otherwise the space on the first air intake side will be too small, resulting in poor air intake. Since the ratio of the inner diameter of the collector 211 to that of the impeller 30 and the ratio of the air intake space in front of the fan to the depth of the corresponding side of the impeller 30 both affect the flow at the leading edge 3401 of the impeller 30, the depth of its waveform segment needs to be considered based on the dimension with a higher influence.

[0081] In this embodiment, the inlet of collector 211 is circular.

[0082] This embodiment also incorporates adaptive design for the wavelength and wave height of the front waveform segment 344. Specifically, the wavelength S1 and wave height N1 of the front waveform segment 344 are closely related to the inlet angle α of the impeller 30 to meet the characteristics of the multi-blade centrifugal fan 13.

[0083] In this embodiment, the wavelength of the front waveform segment 344 of the blade 34 increases sequentially along the length of the blade 34.

[0084] S1 satisfies the following condition:

[0085] And α∈[30°, 90°];

[0086] Where α is the impeller inlet angle of 30°. The larger the inlet angle, the greater the impact, and the smaller the waveform segment is required to break the vortex.

[0087] The wave height N1 of the preceding waveform segment 344 satisfies the following condition:

[0088] 0.1sin(α)L≤N1≤0.4sin(α)L; L is the width dimension of the blade after it is flattened.

[0089] In a further preferred embodiment, the wavelengths of any two adjacent bands in the preceding waveform segment are denoted as Sl. i and Sl i+1 The wave heights are denoted as Nl. i and Nl i+1 ;

[0090] The wavelength and wave height of any two adjacent bands in the preceding waveform segment satisfy the following condition:

[0091] Sl i <Sl i+1 ≤1.3Sl i ;

[0092] 0.8Nl i ≤Nl i+1 <Nl i .

[0093] The straight section 343 of blade 34 corresponds to the main flow area (main work area) at the inlet of impeller 30. This region has stable airflow and few large-scale vortices. Setting a wavy section would disrupt the main flow, generating more small-scale vortices and weakening blade 34, thus reducing its work capacity. Therefore, it is designed as a straight section, with an axial length H3 satisfying the condition: 0.5(H z -H1-H2)≤H3≤(H Z -H1-H2); As mentioned above, the front main straight section 343 is the main airflow area of ​​the inlet leading edge 3401. The airflow is relatively stable and there are relatively few large-scale vortices. Therefore, there is no need to set a waveform section. However, in order to balance the noise reduction effect and the fan performance, the lengths of the waveform section and the straight section need to be designed as described above.

[0094] The section of blade 34 of impeller 30 near the first or second disk is a non-working zone, primarily for recirculation. This is where the airflow direction is from the blade 34 outlet towards the inlet. Adding a waveform structure to the leading edge 3401 of blade 34 would actually reduce the blade passage size. A longer blade passage helps suppress recirculation towards the inlet side; therefore, no waveform structure is used. Instead, a front-secondary straight section 345 is positioned at the leading edge 3401 of the two blade sections 34, closer to the first disk than the front waveform section 344. The extension direction of the front-secondary straight section 345 is parallel to or at an angle to the axis of impeller 30. A portion of the front-secondary straight section 345 and the rear waveform section 346 are opposite each other in the width direction of blade 34. A portion of the rear waveform section 346 opposite the front-secondary straight section 345 in the width direction of blade 34 also corresponds to the recirculation zone at the blade 34 tip. Therefore, a short-wavelength waveform design is used to reduce the intensity of secondary recirculation in the reverse vortex core region.

[0095] In this embodiment, the trailing edge 3402 of the blade 34 of the impeller 30 assembly is designed with matching and coordinated segmentation. Specifically, the design of the trailing edge 3402 of the blade 34 must be coupled with the segmentation of the leading edge 3401 to avoid mutual interference and achieve a coordinated noise reduction effect. The trailing edge 3402, from the end near the front plate 31 to the end away from the front plate 31, sequentially includes: a rear wave segment 346 and a rear straight segment 347.

[0096] The rear waveform segment 346 is crucial for controlling outlet vortex shear and reducing dynamic-static interference. The length of the rear waveform segment along the impeller axis is denoted as H. 20 H 20 The following conditions must be met:

[0097] And 0.8D n ≤D1≤D n 0.5≤H z / H q ≤2, 0.05H Z ≤H4≤0.3H Z Where H4 is the length of the straight section of the trailing edge; considering that the increase in blade length in the mainstream region of the impeller due to the straight section of the trailing edge can enhance work capacity to some extent, it will weaken the noise reduction effect. Therefore, the length of the straight section of the trailing edge should not be too long. At the same time, the length of the straight section of the trailing edge should meet the installation requirements. Specifically, the length of the straight section in the axial direction of the impeller needs to meet 0.05H. Z ≤H4≤0.3H Z .

[0098] To further optimize, the rear waveform segment 346 is divided into two parts: a first waveform segment 3461 and a second waveform segment 3462. The first waveform segment 3461 is close to the front disk 31, and in the width direction of the blade 34, it is at least partially opposite the leading waveform segment 344 of the leading edge 3401. This region corresponds to the non-mainstream work zone and is affected by small-scale vortices after the leading edge 3401 breaks up. A short wavelength design is adopted to reduce the intensity of secondary backflow into the vortex core region. Its maximum wavelength is less than or equal to the minimum wavelength of the second waveform segment 3462. Its wavelength S... 21 and wave height N 21 It has the following limitations:

[0099] Wave height S of the first waveform segment 3461 21 Conditions met: β is the impeller outlet angle, and the value range of β is: 150°≤β≤180°;

[0100] Wave height N of the first waveform segment 3461 21 The condition is satisfied: 0.01sinβL≤N 21 ≤0.15sinβL; where L is the width of the blade after it is flattened;

[0101] The second wave segment 3462 of the trailing edge 3402 of blade 34 is far from the leading disk 31 and, in the width direction of blade 34, is partially opposite to the leading straight segment 343 of the leading edge 3401. This region is located in the mainstream region and employs a larger wavelength design, primarily to alter the vortex shedding frequency of the trailing edge 3402, improve pressure pulsation on the blade surface 34, thereby reducing aerodynamic noise and improving efficiency. Its wavelength S 22 and wave height N 22 The following restrictions apply: S 22 Condition S is satisfied. 21 <S 22 ≤5S 21 ;Wave height N of the second waveform segment 22 Condition: 0.05L≤N 22 ≤0.2L.

[0102] Based on the above limitations, the wavelengths of any two adjacent bands in the first waveform segment 3461 of the blade 34 in this embodiment are respectively denoted as S21. i and S21 i+1 The wave heights are denoted as N21. i and N21 i+1 In the first waveform segment, the wavelength and wave height of any two adjacent bands satisfy the following condition:

[0103] S21 i <S21 i+1 ≤1.3S21 i ;

[0104] 0.8N21 i ≤N21 i+1 <N21 i ;

[0105] The wavelengths of any two adjacent bands in the second waveform segment are denoted as S22. i and S22 i+1 The wave heights are denoted as N22. i and N22 i+1 In the second waveform segment, the wavelength and wave height of any two adjacent bands satisfy the following conditions:

[0106] S22 i <S22 i+1 ≤1.3S22 i ;

[0107] 0.8N22 i ≤N22 i+1 <N22 i .

[0108] In this embodiment, the rear waveform segment 346 of the blade 34 generally follows the principle that "the maximum wavelength of the front waveform segment 344 is less than or equal to the minimum wavelength of the rear waveform segment 346". The above design ensures that the small vortices broken at the leading edge 3401 can be "outflowed at off-peak" through a larger-scale waveform at the trailing edge, effectively suppressing the re-aggregation of vortices and strong pressure pulsation.

[0109] In this embodiment, the rear straight section 347 of the blade 34 is adjacent to the mid-disk 33, which is provided to ensure the strength of the blade 34, installation stability, and airflow smoothness at the end of the mainstream region. Its length H4 satisfies 0.05H z ≤H4≤0.3H z .

[0110] In summary, this embodiment, based on the noise reduction structure design of the leading edge 3401 of the two blade segments 34, implements a matching noise reduction coupling design for the trailing edge 3402 of the two blade segments 34. Each trailing edge 3402 of the blade 34 includes a rear straight segment 347 adjacent to the mid-disk 33 and a rear wave-shaped segment 346 away from the mid-disk 33. A portion of the rear wave-shaped segment 346 is opposite to the front wave-shaped segment 344 of the leading edge 3401 in the width direction of the blade 34. The front main straight segment 343 is opposite to a portion of the rear wave-shaped segment 346 and the rear straight segment 347 in the width direction of the blade 34. By setting the dimensional coupling relationship and matching distribution layout of the leading edge 3401 and trailing edge 3402 waveforms from the perspective of flow mechanism, problems such as weakened work capacity, vortex re-aggregation, increased pressure pulsation, and poor backflow control caused by independent dimensional design or layout of the leading and trailing edges are solved, thereby effectively improving aerodynamic performance and achieving the goal of reducing noise.

[0111] The impeller 30 of this embodiment was installed in a range hood for testing and compared with a prototype machine that uses a conventional straight blade design for the impeller 30. Figure 12 The comparison of simulated pressure cloud diagrams shows that within the narrower flow channel on the left, the rationally arranged trailing edge waveform in the axial direction improves the outlet pressure distribution in the axial direction, enhancing overall uniformity in the axial direction. The internal pressure distribution of the impeller 30 in this invention is more uniform, the vortex region is significantly reduced, and the overall calculated aerodynamic efficiency is increased by 3%. This fully demonstrates that the collaborative segmented design of the trailing edge waveform in this invention effectively reduces noise while not weakening but rather optimizing the aerodynamic performance of the fan.

[0112] The design of the impeller 30 assembly in this embodiment is also applicable to the single-inlet centrifugal fan 13, such as... Figure 8 and Figure 9 As shown, its centrifugal fan 13 is a single-inlet fan. The impeller 30 assembly includes a front disc 31 (first disc) and a rear disc 32 (second disc), with blades 34 disposed between the front and rear discs 32.

[0113] The segmented design concept of the leading edge 3401 and trailing edge 3402 of its blade 34 is exactly the same as that of Embodiment 1. Figure 10 As shown, the leading edge 3401 of the blade 34, starting from near the front disk 31, consists of a front secondary straight segment 345, a front wave segment 344, and a front main straight segment 343; the trailing edge 3402, starting from near the front disk 31, consists of a rear wave segment 346 and a rear straight segment 347. The rear wave segment 346 can also be subdivided into a first wave segment 3461 and a second wave segment 3462.

[0114] The parameter design method is the same as in Example 1, but it should be noted that the axial depth H of the impeller 30 is... zThe total depth is defined as the area from the front disc 31 to the rear disc 32 (the total depth is defined on one side). Test results show that this single-inlet fan also achieved a significant noise reduction effect, while maintaining stable airflow with a slight increase.

[0115] Based on the above embodiments, other embodiments can be obtained by replacing and improving the relevant technical features. For example, the concave or convex portion of the waveform in the aforementioned embodiments can adopt a toothed, arc-shaped, or airfoil structure. For instance, using a sharp toothed shape may result in a more intense vortex-breaking effect; while using a streamlined airfoil structure may make the airflow transition smoother, which is more beneficial to efficiency. The processing method can be stamping, injection molding, or milling. Furthermore, for a dual-inlet fan, the front and rear blade segments can be designed asymmetrically. Specifically, if the front and rear air intake spaces of the range hood are different (H... q前 ≠H q后 If the length H2 of the leading and trailing wave segments of the front and rear blades can be calculated separately and different values ​​can be used to adapt to their respective air intake conditions and achieve optimal overall performance. Furthermore, the leading and trailing straight segments do not necessarily have to be parallel to the impeller axis. They can be designed to form a certain angle with the axis (e.g., 0°–15°) according to the required airflow inlet angle to further optimize air intake conditions and reduce initial impact.

Claims

1. A centrifugal fan impeller assembly, comprising: a first disc and a second disc arranged opposite to each other in a front-rear direction; a plurality of blades connected between the first disc and the second disc and distributed in a circumferential direction, each blade further having a leading edge corresponding to an air inlet side and a trailing edge corresponding to an air outlet side; characterized in that the leading edge of the blade is provided with a front wave segment near the first disc, the trailing edge of the blade is provided with a rear wave segment near the first disc, and a maximum wavelength of the front wave segment is less than or equal to a minimum wavelength of the rear wave segment.

2. The impeller assembly for a centrifugal fan of claim 1, wherein: the leading edge of the blade further comprises a front main straight segment connected to the front wave segment and away from the first disc, and at least part of the rear wave segment is opposite to at least part of the front main straight segment in a width direction of the blade.

3. The impeller assembly for a centrifugal fan of claim 2, wherein: the rear wave segment on the trailing edge of the blade comprises a first wave segment and a second wave segment arranged in sequence from a first end near the first disc to a second end away from the first disc, at least part of the first wave segment is opposite to at least part of the front wave segment of the leading edge of the blade in the width direction of the blade, and the second wave segment is opposite to part of the front main straight segment of the leading edge of the blade in the width direction of the blade.

4. The impeller assembly for a centrifugal fan of claim 3, wherein: a starting point of the first wave segment is closer to the first disc than a connecting point of the front wave segment and the front main straight segment, and a maximum wavelength of the first wave segment is less than or equal to a minimum wavelength of the second rear wave segment.

5. The impeller assembly for a centrifugal fan of claim 4, wherein: the first wave segment and the second wave segment increase in wave shape along the length of the blade in sequence.

6. The impeller assembly for a centrifugal fan of any one of claims 3-5, wherein: The wavelength of the first wave segment is denoted as S 21 , S 21 satisfies the condition: β is an impeller outlet angle, and the value range of β is 150°≤β≤180°.

7. The impeller assembly for a centrifugal fan of any one of claims 3-5, wherein: The wave height of the first wave section is denoted as N 21 and satisfies the condition: 0.01 sin βL ≤ N 21 ≤ 0.15 sin βL; wherein L is the width dimension of the flattened blade.

8. The impeller assembly for a centrifugal fan of any one of claims 3-5, wherein: The wavelength of the second wave segment is denoted as S 22 , S 22 satisfies the condition: S 21 < S 22 ≤ 5S 21 .

9. The impeller assembly for a centrifugal fan of any one of claims 3-5, wherein: The wave height of the second wave segment is denoted as N 22 , N 22 satisfies the condition: 0.05L≤N 22 ≤0.2L.

10. The impeller assembly for a centrifugal fan of any one of claims 3-5, wherein: The wavelengths of any two adjacent wave segments in the first wave segment are respectively denoted as S21 i and S21 i+1 ; the wave heights of any two adjacent wave segments in the first wave segment are respectively denoted as N21 i and N21 i+1 ; and the wavelengths and wave heights of any two adjacent wave segments in the first wave segment satisfy the condition: S21 i <S21 i+1 ≤1.3S21 i ; 0.8 N21 i ≤ N21 i+1 < N21 i .

11. The impeller assembly for a centrifugal fan of any one of claims 3-5, wherein: The wavelength of any two adjacent wave segments in the second wave segment is respectively denoted as S22 i and S22 i+1 ; the wave height of any two adjacent wave segments in the second wave segment is respectively denoted as N22 i and N22 i+1 ; the wavelength and the wave height of any two adjacent wave segments in the second wave segment satisfy the condition: S22 i <S22 i+1 ≤1.3S22 i ;0.8N22 i ≤N22 i+1 <N22 i .

12. The impeller assembly for a centrifugal fan of claim 1, wherein: the wavelength of the front wave segment increases in sequence along the length of the blade.

13. The impeller assembly for a centrifugal fan of claim 12, wherein: The wavelength of the front wave section is denoted as S1, and S1 satisfies the condition: and a ∈ [30°, 90°]; wherein a is an impeller inlet angle; H2 is a length of the front wave section in the axial direction of the impeller.

14. The impeller assembly for a centrifugal fan of claim 12 or 13, wherein: a wave height of the front wave segment is denoted as N1, and satisfies the condition: 0.1sin(α)L≤N1≤0.4sin(α)L; L is a flattened width dimension of the blade.

15. The impeller assembly for a centrifugal fan of claim 12 or 13, wherein: The wavelengths of any two adjacent wave segments in the front wave form section are respectively denoted as Sl i and Sl i+1 The wave heights of any two adjacent wave segments in the front wave form section are respectively denoted as Nl i and Nl i+1 The wavelengths and wave heights of any two adjacent wave segments in the front wave form section satisfy the condition: Sl i <Sl i+1 ≤1.3Sl i ; 0.8 Nl i ≤ Nl i+1 < Nl i .

16. The impeller assembly of claim 2, wherein: the leading edge of the blade further comprises a front auxiliary straight segment arranged closer to the first disc than the front wave segment.

17. A centrifugal fan comprising a volute and an impeller assembly provided in the volute, the impeller assembly being the impeller assembly for a centrifugal fan according to any one of claims 1 to 16, characterized in that: a flow collector is arranged at an air inlet of the volute; a length dimension of the front wave segment in an axial direction of the impeller is denoted as H2, and satisfies the condition: and 0.8D n ≤D1≤D n , 0.5≤H z / H q ≤2; wherein D1 is a maximum diameter of an inlet of the flow collector; D n D is the minimum inner diameter of the impeller; H z is the axial depth of the impeller H q D is the depth of the inlet air space in front of or behind the centrifugal fan in the housing.

18. The centrifugal fan of claim 17, wherein: The blade leading edge further comprises a front sub-straight section arranged closer to the first disc relative to the front wave section, a length dimension H1 of the front sub-straight section in the axial direction of the impeller satisfies the condition: And H0∈[0,30]mm; wherein, H0 is the distance from the first disc of the impeller to the front cover plate or the rear cover plate of the volute.

19. The centrifugal fan of claim 18, wherein: The leading edge further comprises a front main straight section distanced from the first disc; the length dimension of the front main straight section in the direction of the axis of the impeller is denoted as H3, wherein 0.5(H z - H1 - H2) < H3 < (H Z - H1 - H2).

20. The centrifugal fan of claim 17 or 18, wherein: The length dimension of the rear wave-form section in the axial direction of the impeller is denoted as H 20 , H 20 satisfies the following conditions: and 0.8D n ≤D1≤D n , 0.5≤H z / H q ≤2, 0.05H Z ≤H4≤0.3H Z ; wherein H4 is the length dimension of the straight line segment of the trailing edge.

21. A range hood comprising a housing and a centrifugal fan disposed within the housing, characterized by: the centrifugal fan adopts the centrifugal fan according to any one of claims 17-20.

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