Centrifugal fan and range hood

Abstract

The present application relates to the technical field of range hood, and particularly relates to a centrifugal fan and a range hood. The centrifugal fan comprises a volute; the volute comprises a side plate and a surrounding plate, the surrounding plate and the side plate jointly form an inner cavity and an air outlet, a plurality of flow guide fins are arranged at the inner cavity close to the air outlet, a first flow guide air duct is formed between adjacent flow guide fins and between the flow guide fins and the surrounding plate; from the side close to the volute tongue to the side away from the volute tongue along the impeller axis direction, the distance between the end away from the air outlet and the air outlet surface of the air outlet gradually increases in the projection of each flow guide fin. The range hood comprises the above centrifugal fan. The centrifugal fan and the range hood provided by the present application divide the air outlet into a plurality of independent first flow guide air ducts by arranging a plurality of flow guide fins at the inner cavity close to the air outlet, so that the high-speed airflow and the low-speed airflow are respectively separated into different first flow guide air ducts, so as to ensure that the airflow velocity is uniform at the air outlet and prevent the generation of vortex and wind noise.

Description

Technical Field

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

[0002] Centrifugal fans are widely used in range hoods, air conditioning, and ventilation systems. The volute and its internal impeller are the core components of a centrifugal fan. In a centrifugal fan, the impeller blades propel the airflow outward along the tangential direction of the impeller, and the air flows along the profile of the volute inside the volute, finally being discharged from the outlet of the volute.

[0003] Because the volute's profile is an eccentric helix, the distance between the inner wall of the volute and the impeller center varies circumferentially. Starting from the volute's tongue, the distance gradually increases along the helical direction of the volute's profile. That is, near the volute's tongue, the distance between the inner wall of the volute and the impeller's outer profile is smaller, resulting in less flow space and forced acceleration, leading to higher velocity. Further away from the volute's tongue, the distance is larger, resulting in more flow space, diffusion, and deceleration, leading to lower velocity.

[0004] In other words, the space inside the volute near the air outlet is smaller on the side closer to the volute tongue and larger on the side farther from the volute tongue. This results in a higher airflow velocity on the side closer to the volute tongue and a lower airflow velocity on the side farther from the volute tongue. When airflows with different velocity gradients converge at the air outlet, the high-speed airflow and the low-speed airflow merge, which leads to flow instability, the formation of eddies, and the generation of wind noise. Summary of the Invention

[0005] The first technical problem solved by this invention is to provide a centrifugal fan that effectively ensures uniform airflow velocity at the outlet and prevents the generation of eddies and wind noise.

[0006] The second technical problem solved by the present invention is to provide a range hood that further effectively ensures uniform airflow velocity at the air outlet and prevents the generation of eddies and wind noise.

[0007] The first technical problem mentioned above is solved by the following technical solution: A centrifugal fan, comprising a volute and an impeller; The volute includes two side plates and a surrounding plate disposed between the two side plates. The surrounding plate and the two side plates together form an inner cavity and an air outlet communicating with the inner cavity. The impeller is disposed in the inner cavity, and a plurality of parallel guide fins are arranged sequentially at intervals near the air outlet in the inner cavity. The two ends of the guide fins are respectively connected to the two side plates, and a first guide air duct is formed between adjacent guide fins and between the guide fins and the surrounding plate to guide the airflow in the inner cavity to the air outlet. In particular, from the side closer to the volute tongue in the volute to the side farther away from the volute tongue, along the impeller axis, the distance between the end of each guide fin that is farther away from the air outlet and the air outlet surface of the air outlet gradually increases.

[0008] Compared with the prior art, the centrifugal fan of the present invention has the following beneficial effects: In a centrifugal fan, after the airflow is centrifugally thrown out by the impeller, it flows along the volute profile. When it reaches the vicinity of the air outlet, it enters the first guide air duct along the guide fins and flows along the first guide air duct to the air outlet, and is finally discharged from the air outlet.

[0009] Because the airflow velocity is higher near the volute tongue and lower further away from it near the air outlet, this invention employs multiple guide fins near the air outlet to divide the outlet into multiple independent first guide ducts. This separates high-speed and low-speed airflows into different first guide ducts, preventing the direct mixing of airflows with different velocity gradients and thus avoiding eddies and wind noise. Furthermore, since the multiple guide fins are parallel to each other, the directions of the first guide ducts between the guide fins are consistent, allowing the airflow to be guided in an orderly manner within the parallel channels. This eliminates airflow crossing and turbulence caused by non-parallel guide structures, ensuring uniform airflow velocity at the air outlet and further preventing the generation of eddies and wind noise.

[0010] Additionally, it should be noted that, along the impeller axis, the distance between the end of the guide fin projection furthest from the air outlet and the air outlet surface can be considered as the vertical distance between the end of the guide fin projection and the air outlet surface. Because the space within the volute cavity is smaller near the air outlet and larger further away from the volute tongue, in this invention, from the side near the volute tongue to the side further away, the distance between the end of the guide fin projection furthest from the air outlet and the air outlet surface gradually increases. That is, the end of the guide fin projection near the volute tongue is closer to the air outlet. This accommodates the smaller space within the cavity near the volute tongue, preventing interference between the guide fin and the impeller and affecting impeller rotation, and preventing the airflow from directly impacting the guide fin and generating wind noise due to the close proximity of the guide fin to the impeller. The distance between the end of the guide fin projection furthest from the volute tongue and the air outlet surface is also considered. The air outlet is located further away, making full use of the larger space in the inner cavity away from the volute tongue. This allows the tips of the guide fins to penetrate deeper into the inner cavity of the volute, enabling the airflow in the inner cavity to contact the guide fins earlier and be guided into the first guide duct sooner. This reduces the distance the airflow travels freely without guidance, facilitating the introduction of airflow into the first guide duct before the formation of large vortices. It also facilitates the separation of airflows at different speeds before mixing, improving the guiding efficiency of the guide fins, reducing the intensity of vortices generated by the volute, and minimizing airflow energy loss. Therefore, the volute of this invention fully utilizes the non-uniformity of the space near the air outlet in the inner cavity of the volute, maximizing the guiding effect of the guide fins without interference, and alleviating the technical problems of uneven airflow distribution and high noise levels near the air outlet in existing volutes.

[0011] Furthermore, in this invention, the two ends of the guide fins are respectively connected to two side plates to form an overall reinforced frame at the air outlet. This not only improves the rigidity of the guide fins themselves, which helps to ensure that the guide fins remain stable under the impact of high-speed airflow, but also enhances the structural strength of the air outlet of the volute.

[0012] Specifically, firstly, both ends of the guide fins are fixed to the side plates, constraining the fins at both ends and increasing their natural frequency. This makes the fins less prone to resonance and vibration, resulting in smoother centrifugal fan operation. Secondly, each end of the guide fin is connected to one of the two side plates, which serve as positioning references, ensuring the parallelism between the guide fins. Thirdly, when airflow impacts the guide fins, the impact load is transferred to the two side plates of the volute through the connection points at both ends, dispersing it throughout the entire volute structure and avoiding localized stress concentration, thus improving long-term operational reliability.

[0013] In summary, the volute of the present invention achieves orderly airflow by precisely matching the position of the guide fins with the internal cavity space distribution and guiding the airflow in parallel, thereby reducing flow loss and wind noise.

[0014] In one embodiment, along the radial direction of the impeller, the minimum distance between the end of the guide fins furthest from the air outlet and the outer ring profile of the impeller is not less than the volute tongue gap of the volute.

[0015] In one embodiment, the volute has a base circle and a first reference line in a cross section perpendicular to the impeller axis. The center point of the arc of the volute tongue is located on the first reference line, and the first reference line is tangent to the base circle. Along the impeller axis, the end of each guide fin that is furthest from the air outlet is located on the first reference line.

[0016] In one embodiment, the guide fins include an air outlet end located on the air outlet surface of the air outlet, and the air outlet ends of each guide fin are evenly distributed on the air outlet surface, thus dividing the air outlet surface equally.

[0017] In one embodiment, in the opposite direction of the spiral direction of the profile of the volute, the volute includes a volute tongue guide portion extending from the volute tongue to the air outlet surface, the profile of the volute tongue guide portion being a smooth straight line. Along the impeller axis, the extension direction of the guide fin projection is parallel to the extension direction of the profile of the volute near the air outlet on the side away from the volute tongue.

[0018] In one embodiment, in the opposite direction of the spiral direction of the profile of the volute, the volute includes a volute tongue guide portion extending from the volute tongue to the air outlet surface. The profile of the volute tongue guide portion includes a first straight segment and a second straight segment that are bent into each other. The first straight segment is close to the air outlet surface of the air outlet and takes the direction perpendicular to the air outlet surface of the air outlet as the reference direction. The first straight segment extends along the reference direction. The guide fins include a first guide section and a second guide section. One end of the first guide section is the air outlet, and the other end is connected to the second guide section. The first guide section extends in the same direction as the first straight segment.

[0019] In one embodiment, along the impeller axis, the extension direction of the projection of the second guide portion is parallel to the extension direction of the profile of the volute near the air outlet on the side away from the volute tongue.

[0020] In one embodiment, the distance between the end of the first guide portion away from the air outlet and the air outlet surface gradually increases from the side closer to the volute tongue to the side farther away from the volute tongue.

[0021] In one embodiment, the first guide portion near the volute tongue and the first straight segment are of equal length.

[0022] In one embodiment, the volute has a second reference line on a cross section perpendicular to the impeller axis. The first guide portion near the volute tongue has a point on the second reference line at the end away from the air outlet and the midpoint of the first straight segment. In each of the first air guide sections, the end furthest from the air outlet is located on the second baseline.

[0023] In one embodiment, the guide fins are provided with flow holes that can connect to adjacent first guide air ducts, and the flow holes are arranged in an array on the guide fins.

[0024] In one embodiment, the guide fin includes an air inlet end, which is disposed away from the air outlet; along the width direction of the guide fin, the air inlet end is a flow collection structure that gradually protrudes from both ends inward and away from the air outlet surface, and the point farthest from the air outlet surface in the flow collection structure is the protrusion point. The impeller has a central disk and a front disk and a rear disk respectively disposed on both sides of the central disk; Wherein, along the width direction of the guide fin, the guide fin includes a first side and a second side disposed opposite to each other, the first side being disposed near the front plate and the second side being disposed near the rear plate; Along the impeller axis, the distance between the middle disk and the front disk is H1, the distance between the middle disk and the rear disk is H2, the distance between the protruding point and the first side is h1, the distance between the protruding point and the second side is h2, and H1 / H2=h1 / h2.

[0025] In one embodiment, the protruding point is located on the plane where the middle disk is located.

[0026] In one embodiment, the air inlet end of the guide fin is provided with a plurality of diversion protrusions, the plurality of diversion protrusions are arranged sequentially along the width direction of the guide fin, and along the width direction of the guide fin, each diversion protrusion gradually protrudes from both ends inward toward the direction away from the air outlet surface.

[0027] In one embodiment, the number of guide fins is 2-6.

[0028] In one embodiment, the side plate of the volute is provided with a plurality of flow guiding structures, and a second flow guiding duct is formed between adjacent flow guiding structures and between the flow guiding structure and the enclosure plate. The second flow guiding duct is connected to the air inlet side of the plurality of first flow guiding ducts in a one-to-one correspondence.

[0029] In one embodiment, the flow guiding structure extends along the profile direction of the volute.

[0030] In one embodiment, the two ends of the guide fins are bent to form a mounting plate; The two ends of the guide fin are respectively mounted on the two side plates via the mounting plate; and / or, the air outlet end of the guide structure extends from the air inlet end of the guide fin to the air outlet to form an extension section, the extension direction of the extension section is the same as the extension direction of the guide fin, and the two ends of the guide fin are respectively mounted on the extension section on the two side plates via the mounting plate.

[0031] In one embodiment, the air inlet end of the air guide structure is tangent to the base circle of the volute.

[0032] The second technical problem mentioned above is solved by the following technical solution: A range hood comprising the aforementioned centrifugal fan.

[0033] Compared with the prior art, the range hood described in this invention has the following advantages: by setting the centrifugal fan inside the range hood, the range hood has all the advantages of the centrifugal fan, which will not be elaborated here. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 One of the structural schematic diagrams of a centrifugal fan provided in an embodiment of the present invention (one side plate is not shown); Figure 2 A second schematic diagram of the centrifugal fan provided in an embodiment of the present invention (one side plate is not shown); Figure 3 This is an enlarged view of a partial structure of a centrifugal fan provided in an embodiment of the present invention; Figure 4 One of the cross-sectional views of a centrifugal fan provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the side plate in the centrifugal fan provided in an embodiment of the present invention; Figure 6 A second cross-sectional view of a centrifugal fan provided in an embodiment of the present invention; Figure 7 The third cross-sectional view of the centrifugal fan provided in the embodiment of the present invention; Figure 8 for Figure 7 A magnified view of the local structure of part A in the image; Figure 9 This is a schematic diagram of the structure of the guide fins in the centrifugal fan provided in an embodiment of the present invention; Figure 10 This is an enlarged view of a portion of the structure of the guide fins in a centrifugal fan provided in an embodiment of the present invention; Figure 11 This is one of the schematic diagrams of the first structure of the volute in a centrifugal fan provided in an embodiment of the present invention; Figure 12 A second schematic diagram of the first structure of the volute in a centrifugal fan provided in an embodiment of the present invention (marked with a first reference line and a base circle). Figure 13 This is one of the schematic diagrams of the second structure of the volute in a centrifugal fan provided in an embodiment of the present invention; Figure 14 This is a second schematic diagram of the second structure of the volute in a centrifugal fan provided in an embodiment of the present invention (marked with a first reference line, a second reference line, and a base circle).

[0036] Figure label: 11-Side panel; 12-Enclosure panel; 13-Air outlet; 14-Vortex tongue guide section; 141-First straight section; 142-Second straight section; 2-Guide fins; 21-First guide section; 22-Second guide section; 23-Air inlet; 24-Air outlet; 25-Flow hole; 26-Protrusion point; 27-Diverter protrusion; 28-Mounting plate; 29-First guide duct; 2a-First side; 2b-Second side; 3-Impeller; 31-Middle plate; 321-Front plate; 322-Rear plate; 4-Flow guiding structure; 41-Second flow guiding duct; 42-Extension section; 5-The center point of the arc of the spiral tongue's profile; a - Base circle; b - First datum line; c - Second datum line; d - Helical direction of the volute profile; e - Datum direction; h1 - the distance between the protruding point and the first side of the guide fin; h2 - The distance between the protruding point and the second side of the guide fin; H1 - The distance between the middle plate and the front plate of the impeller; H2 - The distance between the impeller's center plate and the rear plate. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] In the description of this application, it should be understood that the terms "center", "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0039] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] Please see Figure 1 This invention provides a centrifugal fan, which includes a volute and an impeller 3. The volute includes two side plates 11 and a surrounding plate 12 disposed between the two side plates 11. The surrounding plate 12 and the two side plates 11 together form an inner cavity and an air outlet 13 communicating with the inner cavity. The impeller 3 is disposed in the inner cavity, and a plurality of parallel guide fins 2 are sequentially and spaced apart near the air outlet 13. The two ends of the guide fins 2 are respectively connected to the two side plates 11, and a first guide duct 29 is formed between adjacent guide fins 2 and between the guide fins 2 and the surrounding plate 12 to guide the airflow in the inner cavity to the air outlet 13. See also... Figure 11 Along the axis of the impeller 3, from the side closest to the volute tongue in the volute to the side furthest from the volute tongue, the distance between the end of each guide fin 2 furthest from the air outlet 13 and the air outlet surface of the air outlet 13 gradually increases in the projection of each guide fin 2.

[0042] It should be noted that, since the two ends of the guide fin 2 are respectively connected to the two side plates 11, multiple fins are arranged at intervals between the side near the volute tongue and the side away from the volute tongue in the part of the enclosure 12 near the air outlet 13. Thus, a first guide air duct 29 is formed between adjacent guide fins 2, between the guide fin 2 and the side of the enclosure 12 near the volute tongue, and between the guide fin 2 and the side of the enclosure 12 away from the volute tongue.

[0043] In the centrifugal fan, after the airflow is centrifugally thrown out from the impeller 3, it flows along the volute profile. When it reaches the air outlet 13, it enters the first guide air duct 29 along the guide fins 2 and flows along the first guide air duct 29 to the air outlet 13, and is finally discharged from the air outlet 13.

[0044] Because the airflow velocity is higher near the volute tongue side and lower away from the volute tongue side near the air outlet 13, this invention provides multiple guide fins 2 near the air outlet 13 in the inner cavity, dividing the air outlet 13 into multiple independent first guide air channels 29. This separates high-speed and low-speed airflows into different first guide air channels 29, avoiding the direct mixing of airflows with different velocity gradients that would generate eddies and wind noise. Furthermore, since the multiple guide fins 2 are parallel to each other, the first guide air channels 29 between each guide fin 2 are aligned, and the airflow is guided in an orderly manner in the parallel channels. This eliminates the airflow crossing and turbulence caused by non-parallel guide structures within the first guide air channels 29, which helps to ensure uniform airflow velocity at the air outlet 13 and further prevents the generation of eddies and wind noise.

[0045] Additionally, it should be noted that the distance between the end of the guide fin 2 furthest from the air outlet 13 and the air outlet surface of the air outlet 13 in the projection can be considered as the vertical distance between the end of the guide fin 2 projection and the air outlet surface of the air outlet 13. Because the space within the volute cavity is smaller near the air outlet 13 and larger away from it, in this invention, from the side near the air outlet 13 to the side away from it, the distance between the end of the guide fin 2 furthest from the air outlet 13 and the air outlet surface of the air outlet 13 in the projection gradually increases. That is, the end of the guide fin 2 projection near the air outlet 13 is closer to the air outlet 13, to accommodate the smaller space within the cavity near the air outlet 13, preventing interference between the guide fin 2 and the impeller 3 and affecting the rotation of the impeller 3, and preventing the airflow from the impeller 3 from directly impacting the guide fin 2 and generating wind noise due to the close proximity of the guide fin 2 and the impeller 3. The distance from the air outlet 13 is relatively large, making full use of the greater space in the inner cavity away from the volute tongue. This allows the end of the guide fin 2 to penetrate deeper into the inner cavity of the volute, enabling the airflow in the inner cavity to contact the guide fin 2 earlier and be guided into the first guide duct 29 earlier. This reduces the distance the airflow travels freely without guidance, facilitating the introduction of airflow into the first guide duct 29 before the formation of large vortices. It also facilitates the separation of airflows at different speeds before mixing, improving the guiding efficiency of the guide fin 2, reducing the intensity of vortices generated by the volute, and reducing the energy loss of the airflow. Therefore, the volute of this invention fully utilizes the non-uniformity of the space near the air outlet 13 in the inner cavity of the volute, maximizing the guiding effect of the guide fin 2 without interference, and alleviating the technical problems of uneven airflow distribution and high noise in the prior art near the air outlet 13 of the volute.

[0046] In summary, the volute of the present invention achieves orderly airflow by precisely matching the position of the guide fins 2 with the spatial distribution of the inner cavity and guiding the airflow in parallel, thereby reducing flow loss and wind noise.

[0047] Furthermore, in this invention, the two ends of the guide fin 2 are respectively connected to the two side plates 11 to form an overall reinforced frame at the air outlet 13. This not only improves the rigidity of the guide fin 2 itself, which helps to ensure that the guide fin 2 remains stable under the impact of high-speed airflow, but also enhances the structural strength of the air outlet 13 of the volute.

[0048] Specifically, firstly, both ends of the guide fins 2 are fixed to the side plates 11, constraining both ends of the guide fins 2 and increasing their natural frequency. This makes the guide fins 2 less prone to resonance and vibration, resulting in smoother operation of the centrifugal fan. Secondly, both ends of the guide fins 2 are connected to the two side plates 11, which serve as positioning references, ensuring the parallelism between the guide fins 2. Thirdly, when airflow impacts the guide fins 2, the impact load is transferred to the two side plates 11 of the volute through the connection points at both ends, dispersing it throughout the entire volute structure, avoiding localized stress concentration, and improving long-term operational reliability.

[0049] In the above embodiments, please refer to Figure 2 Along the radial direction of the impeller 3, in the projection of the guide fin 2, the minimum distance between the end away from the air outlet 13 and the outer ring profile of the impeller 3 is not less than the volute tongue gap of the volute.

[0050] It should be noted that, along the radial direction of the impeller 3, the distance between the end of the guide fin 2 furthest from the outlet 13 and the outer ring profile of the impeller 3 reflects the position of the end of the guide fin 2 projection relative to the impeller 3.

[0051] Among them, the volute tongue clearance refers to the radial distance from the tip of the volute tongue closest to the impeller 3 to the outer ring profile of the impeller 3, which is the radial distance from the base circle a of the volute to the outer ring profile of the impeller 3. It is a key parameter in the design of centrifugal fans, and its size directly affects the aerodynamic performance and noise level of the fan.

[0052] In addition, the minimum distance between the end of the projection of the guide fin 2 and the outer ring profile of the impeller 3 along the radial direction of the impeller 3 is not less than the volute tongue gap. That is to say, along the radial direction of the impeller 3, the distance between the end of the projection of each guide fin 2 that is far from the air outlet 13 and the outer ring profile of the impeller 3 is not less than the volute tongue gap.

[0053] This design has two advantages. First, if the projected end of the guide fin 2 is too close to the outer ring profile of the impeller 3, vibration, thermal expansion, or manufacturing tolerances may cause the guide fin 2 to collide with the impeller 3 during high-speed rotation, resulting in equipment damage. Therefore, setting the distance between the projected end of the guide fin 2 and the outer ring profile of the impeller 3 to be no less than the volute tongue clearance ensures a safe distance between the guide fin 2 and the impeller 3, effectively preventing mechanical interference. Second, when the guide fin 2 is too close to the impeller 3, the high-speed airflow ejected from the impeller 3 will directly impact the guide fin 2, generating severe airflow impact noise. This impact noise has high-frequency characteristics and significantly affects the user experience. Therefore, this invention sets the distance between the projected end of the guide fin 2 and the outer ring profile of the impeller 3 to be no less than the volute tongue clearance, ensuring that the projected end of the guide fin 2 is outside the volute tongue clearance, thus avoiding direct airflow impact and reducing aerodynamic noise. Thirdly, when the end of the projection of the guide fin 2 is at a sufficient distance from the outer ring profile of the impeller 3, the airflow has enough space to diffuse and turn naturally after being thrown out of the impeller 3, and then smoothly enters the first guide duct 29 formed by the guide fin 2. This design avoids the airflow being forced to make a sharp turn due to the close distance, and reduces flow loss.

[0054] In any of the above embodiments, please refer to Figure 12 On a cross section perpendicular to the axis of the impeller 3, the volute has a base circle a and a first reference line b. The center point 5 of the arc of the volute tongue is located on the first reference line b, and the first reference line b is tangent to the base circle a. Along the axis of the impeller 3, in the projection of each guide fin 2, the end away from the air outlet 13 is located on the first reference line b.

[0055] It should be noted that the base circle a of the volute is the starting reference circle for the volute profile design. Its diameter is usually slightly larger than the outer diameter of the impeller 3. The spiral of the volute is usually a logarithmic spiral or an Archimedean spiral that unfolds from the base circle a.

[0056] In addition, the volute tongue is a key structural feature in the centrifugal fan casing. Located near the base circle a, it forms the structure between the starting point of the casing helix and the outlet diffuser section. In the casing profile, the arc segment of the volute tongue is typically tangentially connected to the base circle a.

[0057] Wherein, the first reference line b is the arc center point 5 passing through the profile of the volute tongue and is a straight line tangent to the base circle a. Since the radial distance between the base circle a of the volute and the outer ring profile of the impeller 3 is the volute tongue gap, the first reference line b is tangent to the base circle a. When the end of each guide fin 2 that is away from the air outlet 13 is located at the first reference line b, the distance between the end of each guide fin 2 that is away from the air outlet 13 and the outer ring profile of the impeller 3 is not less than the volute tongue gap of the volute. And the first reference line b passes through the arc center point 5 of the profile of the volute tongue. Therefore, it is possible to achieve that from the side closer to the volute tongue to the side farther away from the volute tongue, the distance between the end of each guide fin 2 that is away from the air outlet 13 and the air outlet 13 gradually increases.

[0058] This configuration, through precise matching and parallel guidance of the position of the guide fins 2 with the internal cavity space distribution, achieves orderly airflow, reducing flow loss and wind noise.

[0059] In any of the above embodiments, please refer to Figure 11 and Figure 13 The guide fin 2 includes an air outlet 24, which is located on the air outlet surface of the air outlet 13. The air outlets 24 of each guide fin 2 are evenly distributed on the air outlet surface, thus dividing the air outlet surface evenly.

[0060] It should be noted that the guide fin 2 also includes an air inlet end 23, an air outlet end 24 which is arranged opposite to the air inlet end 23, and the air outlet end 24 is arranged close to the air outlet 13 of the volute.

[0061] In this configuration, the outlet ends 24 of each guide fin 2 are evenly distributed on the outlet surface of the volute, dividing the outlet surface into several surfaces of equal length. Therefore, firstly, the outlet ends 24 are located on the outlet surface, aligning the guide fins 2 with the boundary of the outlet 13. The airflow flows directly out of the outlet 13 after exiting the first guide duct 29, without steps or gaps, preventing airflow leakage through the gap between the guide fins 2 and the volute, ensuring a smooth airflow transition without leakage loss. Secondly, this ensures uniform airflow distribution at the outlet 13, mitigating the velocity gradient caused by inconsistent outlet areas.

[0062] As the first feasible method, please refer to Figure 11 Along the opposite direction of the spiral direction d of the volute profile, the volute includes a volute tongue guide section 14 extending from the volute tongue to the air outlet 13. The profile of the volute tongue guide section 14 is a smooth straight line. The extension direction of the projection of the guide fins 2 along the impeller 3 axis is parallel to the extension direction of the volute profile on the side away from the volute tongue near the air outlet 13.

[0063] It should be noted that the opposite direction of the spiral direction d of the volute profile is the opposite direction to the spiral advance of the airflow inside the volute.

[0064] The area near the air outlet 13 refers to the section of the volute profile near the air outlet 13, located on the side of the volute furthest from the volute tongue. Using this section of the volute profile as a reference, and ensuring that the extension direction of the guide fin 2 is parallel to the extension direction of this profile, it is possible to guarantee that the extension direction of the guide fin 2 is consistent with the mainstream direction of the volute outlet section. When the airflow passes through the guide fin 2, it can be smoothly guided to the air outlet 13, avoiding impact losses and flow deviation caused by sudden changes in direction, improving the uniformity of the outlet airflow, and thus enhancing the overall efficiency of the unit.

[0065] As a second possible approach, please refer to Figure 13 In the opposite direction of the spiral direction d of the volute profile, the volute includes a volute tongue guide portion 14 extending from the volute tongue to the air outlet 13. The profile of the volute tongue guide portion 14 includes a first straight segment 141 and a second straight segment 142 that are bent into each other. The first straight segment 141 is close to the air outlet 13 and takes the direction perpendicular to the air outlet 13 as the reference direction e. The first straight segment 141 extends along the reference direction e.

[0066] See also Figure 13 The guide fin 2 includes a first guide portion 21 and a second guide portion 22. One end of the first guide portion 21 is the air outlet 24, and the other end is connected to the second guide portion 22. The end of the second guide portion 22 away from the first guide portion 21 is the air inlet 23, and the first guide portion 21 extends in the same direction as the first straight segment 141.

[0067] It should be noted that the opposite direction of the spiral direction d of the volute profile is the opposite direction to the spiral advance of the airflow inside the volute.

[0068] The first straight segment 141 extends along the reference direction e, and the second straight segment 142 extends at an angle relative to the reference direction e. The guide fin 2 includes a first guide portion 21 and a second guide portion 22 connected to each other. The end of the first guide portion 21 away from the second guide portion 22 is the air outlet 24, and the end of the second guide portion 22 away from the first guide portion 21 is the air inlet 23. That is, the first guide portion 21 is close to the first straight segment 141, and both the first guide portion 21 and the first straight segment 141 extend along the reference direction e.

[0069] In this configuration, the guide fins 2 are clearly divided into a first guide section 21 and a second guide section 22, with the first guide section 21 extending along the reference direction e. The first guide section 21 extending along the reference direction e and the first straight segment 141 of the volute tongue guide section 14, which also extends along the reference direction e, work together in the air outlet 13 region to construct a smooth air outlet channel extending along the reference direction e. This allows the airflow to be distributed more evenly and flow vertically out of the air outlet 13, significantly improving air outlet efficiency and airflow stability.

[0070] In any of the above embodiments, please refer to Figure 13 Along the axis of impeller 3, the extension direction of the projection of the second guide section 22 is parallel to the extension direction of the profile of the volute near the air outlet 13 on the side away from the volute tongue.

[0071] In other words, the volute of the present invention, through the above-described structure, forms an airflow guiding path of "inlet end 23 — second guide section 22 — first guide section 21 — outlet end 24" with the guide fins 2. The first guide section 21, extending along the reference direction e, spatially corresponds to the first straight segment 141 of the volute tongue guide section 14, which also extends along the reference direction e, and together they define a guide channel extending along the reference direction e in the region of the outlet 13. This design allows the airflow to be collected and guided by the second guide section 22 when passing through the guide fins 2, and then stably flow out through the first guide section 21 extending along the reference direction e in the direction of extension along the reference direction e.

[0072] The second guide section 22, serving as the main guiding section of the guide fin 2, extends in a direction parallel to the extension direction of the profile of the volute away from the volute tongue. This ensures that when airflow passes through the second guide section 22, it flows smoothly in the mainstream direction defined by the volute profile, avoiding impact losses and flow deviation caused by sudden changes in direction. This parallel relationship, combined with the first guide section 21 extending along the reference direction e, creates a guide path for the guide fin 2 as a whole that "first follows the direction of the volute profile, then extends along the reference direction," further improving the uniformity and flow efficiency of the airflow in the outlet 13 area.

[0073] In any of the above embodiments, please refer to Figure 13 From the side closer to the volute tongue to the side farther away from the volute tongue, the distance between the end of the first guide section 21 away from the air outlet 24 and the air outlet surface of the air outlet 13 gradually increases.

[0074] In other words, the length of the first guide section 21 gradually increases from the side of the volute tongue towards the side away from the volute tongue. This arrangement ensures that the air inlet position of each first guide section 21 is precisely matched with the spatial distribution of the volute's inner cavity: the space is smaller near the volute tongue side, so the first guide section 21 is shorter to prevent interference with the impeller and avoid direct airflow impact; the space is larger away from the volute tongue side, so the first guide section 21 is longer to make full use of the space and extend the guide path.

[0075] Through this gradient structure, the first guide section 21 can differentiate the airflow at different positions in the air outlet 13 area, so that the airflow can achieve a more uniform velocity distribution and avoid the formation of vortex areas caused by excessively high or low local flow velocities, thereby further improving the air outlet efficiency and airflow stability.

[0076] In any of the above embodiments, please refer to Figure 13 The first guide section 21 near the volute tongue and the first straight segment 141 are of equal length.

[0077] In other words, the first guide section 21 near the volute tongue is the same length as the first straight segment 141, and the length of the first guide section 21 gradually increases in the direction away from the volute tongue.

[0078] This configuration, by setting the first guide section 21 near the volute tongue to have the same length as the first straight segment 141, ensures a precise geometric correspondence between the guide fins 2 and the volute in the outlet 13 region. This equal-length configuration ensures that the guide channel extending along the reference direction e has a consistent length near the volute tongue, thereby creating a stable airflow guidance path in this critical area. This avoids airflow deflection or localized vortices caused by length mismatches, enhancing the coordination of the guide structure and the smoothness of the airflow.

[0079] In any of the above embodiments, please refer to Figure 14 In the cross section perpendicular to the axis of the impeller 3, the volute also has a second reference line c. In the first guide section 21 near the volute tongue, the end away from the air outlet 24 and the midpoint of the first straight segment 141 are both located on the second reference line c.

[0080] Please continue reading Figure 13By setting a second reference line c, and ensuring that the end of the first guide section 21 closest to the volute tongue, away from the air outlet 24, and the midpoint of the first straight segment 141 are both located on this reference line, while simultaneously ensuring that the ends of each first guide section 21, away from the air outlet 24, are all located on this second reference line c, a collinear arrangement of all guide fins 2 connection points is achieved. This design ensures that multiple guide fins 2 form a coordinated and unified spatial arrangement, maintaining a consistent relative positional relationship between each guide fin 2 and the volute profile, further optimizing the airflow guidance path and improving flow consistency under multi-fin arrangement.

[0081] In any of the above embodiments, please refer to Figure 9 and Figure 10 The guide fin 2 is provided with flow holes 25 that can connect to the adjacent first guide air duct 29, and the flow holes 25 are arranged in an array on the guide fin 2.

[0082] For example, the flow holes 25 are evenly distributed in an array along the length and / or width direction on the guide fin 2. The arrayed flow holes 25 can achieve uniform gas exchange across the entire surface of the guide fin 2, avoid local pressure concentration, and help improve the rectification effect and structural stability of the guide fin 2.

[0083] It should be noted that when the airflow velocities within two adjacent first guide ducts 29 are inconsistent, a pressure difference will occur between them. The volute of this invention, by providing flow holes 25, allows airflow within adjacent first guide ducts 29 to exchange gases, balancing the pressure difference between adjacent ducts, reducing the vibration of the guide fins 2 caused by the pressure difference, and improving structural stability. Simultaneously, it allows airflows with different velocity gradients to mix and be rectified as they pass through the flow holes 25, thereby merging into a more uniform fluid, reducing the turbulence intensity and velocity gradient at the outlet 13, and decreasing vibration and noise.

[0084] In any of the above embodiments, please refer to Figure 6 and Figure 9 Along the width direction of the guide fin 2, the air inlet end 23 of the guide fin 2 is a flow collection structure that gradually protrudes from both ends inward and away from the air outlet surface. In the flow collection structure, the point farthest from the air outlet surface is the protrusion point 26.

[0085] Please continue reading Figure 6 The impeller 3 has a central disk 31 and a front disk 321 and a rear disk 322 respectively disposed on both sides of the central disk 31. The guide fin 2 includes a first side 2a and a second side 2b disposed opposite to each other along the width direction of the guide fin 2. The first side 2a is disposed near the front disk 321 and the second side 2b is disposed near the rear disk 322.

[0086] Along the axis of impeller 3, the distance between the middle disk 31 and the front disk 321 is H1, the distance between the middle disk 31 and the rear disk 322 is H2, the distance between the protruding point 26 and the first side 2a is h1, and the distance between the protruding point 26 and the second side 2b is h2, and H1 / H2=h1 / h2.

[0087] It should be noted that the first side 2a of the guide fin 2 is positioned near the front plate 321, and the second side 2b is positioned near the rear plate 322, thus the protrusion 26 is positioned near the middle plate 31. For example, in Figure 6 In this configuration, the protruding point 26 can be located slightly above the center plate 31, slightly below the center plate 31, or on the plane of the center plate 31. Its position is not limited; it can be slightly above or slightly below. Preferably, the protruding point 26 is located on the plane of the center plate 31.

[0088] In particular, since the gas flow rate near the middle disk 31 of the impeller 3 is relatively large, by setting the air inlet end 23 of the guide fin 2 as a centrally protruding flow collection structure, the relatively concentrated airflow near the middle disk 31 can be guided in advance along the protruding surface of the flow collection structure to the first side 2a and the second side 2b, so that the airflow is more evenly distributed in the axial direction, avoiding excessive concentration of airflow in the middle disk 31 area, reducing eddies caused by concentrated airflow, and reducing aerodynamic noise; at the same time, this structure can also prevent the periodic airflow discharged from the impeller 3 from impacting the guide fin 2 at the same time, thereby reducing the noise caused by periodic airflow pulsation.

[0089] In addition, the setting of H1 / H2=h1 / h2 achieves aerodynamic matching between the guide fins 2 and the impeller 3.

[0090] Specifically, H1 and H2 are structural parameters of the impeller 3, reflecting the axial airflow distribution characteristics of the impeller 3. h1 and h2 are the protrusion parameters of the guide fin 2. H1 / H2 = h1 / h2, that is, the proportion of the protrusion point 26 of the guide fin 2 is consistent with the axial dimension proportion of the impeller 3. In other words, the position ratio of the disk 31 of the impeller 3 is calculated by the structural parameters H1 and H2 of the impeller 3: H1 / H2. Based on this ratio, the guide fin 2 is selected so that the h1 / h2 parameter in the guide fin 2 is equal to the proportion of H1 / H2. The selection of the guide fin 2 based on the impeller 3 is completed. Then, the protrusion point 26 of the guide fin 2 is aligned with the position of the disk 31 of the impeller 3, so that the protrusion point 26 is located on the plane of the disk 31. This ensures that the position of the protrusion point 26 of the guide fin 2 is precisely matched with the axial airflow distribution characteristics of the impeller 3. The protrusion point 26 can guide the concentrated airflow near the disk 31 to both sides in advance, so that the airflow is more evenly distributed in the axial direction.

[0091] In summary, the centrifugal fan of the present invention uses the structural parameters (H1 / H2) of the impeller 3 as the selection basis for the guide fins 2, ensuring that each impeller 3 can be matched with the most suitable guide fins 2, avoiding the uncertainty of empirical selection, and achieving the maximum aerodynamic matching effect.

[0092] The protruding point 26 is located on the plane of the central disk 31, and the protruding point 26 of the guide fin 2 is aligned axially with the central disk 31 of the impeller 3. Since the area near the central disk 31 is the region with the largest airflow, the protruding point 26 is located precisely in this region, enabling it to capture the concentrated airflow and guide it to both sides immediately.

[0093] In any of the above embodiments, please refer to Figure 10 The air inlet end 23 of the guide fin 2 is provided with multiple diversion protrusions 27. The multiple diversion protrusions 27 are arranged sequentially along the width direction of the guide fin 2. Along the width direction of the guide fin 2, each diversion protrusion 27 gradually protrudes from both ends inward and away from the air outlet surface, so that the side of the diversion protrusion 27 away from the air outlet surface can guide the airflow. The diversion protrusion 27 is, for example, an arc-shaped protrusion, a trapezoidal protrusion, or a triangular protrusion.

[0094] With this configuration, when the high-speed airflow flows out from the impeller 3 and impacts the air inlet end 23 of the guide fin 2, the guide tips of multiple diversion protrusions 27 divide and split the airflow, causing the high-speed airflow to be guided and dispersed along the guide tip surface of each diversion protrusion 27, splitting it into multiple small airflows. This avoids the high-speed airflow directly impacting the entire air inlet end 23 of the guide fin 2, thereby significantly reducing airflow impact loss. In addition, through the guiding effect of the diversion protrusions 27, the airflow flows smoothly along the protrusion surface, avoiding flow separation caused by airflow impact and reducing vortex formation. Furthermore, through the synergistic effect of the above-mentioned diversion and suppression of flow separation, aerodynamic noise is effectively reduced, and the acoustic performance of the centrifugal fan is improved.

[0095] In summary, the design of the diversion protrusion 27 can prevent high-speed airflow from directly impacting the entire air inlet end 23 of the guide fin 2, thereby reducing airflow impact loss, suppressing flow separation, and reducing aerodynamic noise.

[0096] In any of the above embodiments, please refer to Figure 4The number of guide fins 2 is 2-6. For example, the number of guide fins 2 can be two, three, four, five, or six. If the number of guide fins 2 is too small, such as less than 2, the airflow at the outlet 13 cannot be effectively rectified and guided, and the airflow will still have a large velocity gradient, affecting the uniformity of the airflow. If the number of guide fins 2 is too large, such as more than 6, it will occupy too much of the cross-sectional area of ​​the outlet 13, resulting in a significant increase in exhaust resistance and a reduction in fan efficiency. By controlling the number of guide fins 2 within the range of 2 to 6, sufficient airflow rectification and guidance can be achieved, while avoiding resistance losses caused by too many fins, thus achieving the best balance between airflow uniformity and flow efficiency in the centrifugal fan.

[0097] In any of the above embodiments, please refer to Figure 2 and Figure 3 and combined Figure 4 Multiple airflow guiding structures 4 are provided on the side plate 11 of the volute. A second airflow guiding duct 41 is formed between adjacent airflow guiding structures 4 and between the airflow guiding structure 4 and the surrounding plate 12. The second airflow guiding duct 41 is connected to the air inlet side of multiple first airflow guiding ducts 29 in a corresponding manner.

[0098] In other words, the second air guide duct 41 has an air inlet side and an air outlet side. The air inlet side of the second air guide duct 41 is connected to the internal cavity of the volute to collect the airflow thrown out from the impeller 3. The air outlet side of the second air guide duct 41 is connected to the air inlet side of the first air guide duct 29. Multiple second air guide ducts 41 are arranged one-to-one with multiple first air guide ducts 29 and are interconnected to guide the collected airflow to the first air guide duct 29 and discharge it through the first air guide duct 29.

[0099] For example, the flow guiding structure 4 is a flow guiding convex hull provided towards the impeller 3.

[0100] This configuration places the second guide duct 41 upstream of the first guide duct 29, enabling it to pre-divert and guide the airflow ejected by the impeller 3, directing airflows with different velocity gradients into their respective first guide ducts 29, thus reducing the velocity gradient in the radial direction inside the fan. Furthermore, by setting the second guide duct 41 in a one-to-one correspondence with the first guide duct 29, each first guide duct 29 receives an independent airflow supply. In summary, through the aforementioned diversion and guidance, the airflow velocity distribution entering the guide fins 2 becomes more uniform, reducing the turbulence intensity at the outlet, thereby reducing aerodynamic noise and vibration, and improving the fan's efficiency.

[0101] In any of the above embodiments, please refer to Figure 2 The flow guiding structure 4 extends along the profile of the volute, that is, the flow guiding structure 4 extends from the inside to the outside along the spiral profile of the volute.

[0102] This configuration allows the airflow ejected by impeller 3 to flow smoothly in its original direction after entering the guide structure 4, avoiding flow losses caused by sudden changes in the flow channel direction. Furthermore, the airflow will not undergo violent turning during the guide process, thereby reducing vortex formation, lowering turbulence intensity, and improving the overall performance of the centrifugal fan.

[0103] In any of the above embodiments, please refer to Figure 1 and Figure 6 The two ends of the guide fin 2 are bent to form mounting plates 28. The two ends of the guide fin 2 are respectively mounted on the two side plates 11 through the mounting plates 28. For example, the bending angle of the mounting plate 28 relative to the guide fin 2 is 90 degrees.

[0104] During assembly, the mounting plate 28 at one end of the guide fin 2 is attached to one side plate 11, and the mounting plate 28 at the other end of the guide fin 2 is attached to another side plate 11. Fasteners such as screws are used to pass through the mounting holes on the mounting plate 28 and fix them to the side plate 11, so that the guide fin 2 is securely installed between the two side plates 11 of the volute.

[0105] The above structure enables the main body of the guide fin 2 to be suspended inside the volute, thereby guiding the airflow.

[0106] The above installation method allows the mounting plate 28 to form a surface contact with the volute side plate 11. After being fixed by fasteners, the connection is stable and reliable, preventing the guide fins 2 from shaking or falling off under the impact of airflow. In addition, the mounting plate 28 has a simple structure and is easy to manufacture. During assembly, the mounting plate 28 only needs to be attached to the side plate 11 and fixed, without the need for a complex positioning structure, which improves assembly efficiency.

[0107] Alternatively, please see Figure 5 and combined Figure 7 and Figure 8 The air outlet of the flow guiding structure 4 extends from the air inlet 23 of the flow guiding fin 2 to the air outlet 13 to form an extension section 42. The extension direction of the extension section 42 is the same as the extension direction of the flow guiding fin 2. The two ends of the flow guiding fin 2 are respectively mounted on the extension section 42 on the two side plates 11 through the mounting plate 28.

[0108] In other words, the mounting plate 28 is connected to the extension section 42 on the side plate 11, so that the guide fins 2 form an integral guide system with the side plate 11 through the extension section 42, and thus the extension section 42 undertakes the dual functions of guide and installation.

[0109] With this configuration, the extension direction of the extension section 42 is the same as that of the guide fins 2, allowing the guide structure 4 and the guide fins 2 to connect naturally in the airflow direction, forming a continuous guide channel from the inside of the volute to the outlet 13. After the airflow enters from the guide structure 4, it smoothly transitions between the guide fins 2 without abrupt changes in direction, avoiding separation losses and vortex noise caused by airflow turning.

[0110] In addition, the flow guiding structure 4 is a flow guiding protrusion provided to the impeller 3, and the flow guiding fins 2 are installed on the extension section 42. On the one hand, it can make the installation of the flow guiding fins 2 more stable; on the other hand, by hiding the fasteners in the recess of the flow guiding protrusion, the surface of the volute can be made more aesthetically pleasing.

[0111] In any of the above embodiments, please refer to Figure 2 The air inlet end of the flow guide structure 4 is tangent to the base circle a of the volute. That is, the starting position of each flow guide structure 4 is located on the base circle a of the volute and extends along the profile of the volute towards the side closer to the air outlet 13. Therefore, the air inlet end of each flow guide structure 4 is equidistant from the center of the impeller 3.

[0112] This configuration has several advantages. First, the air inlet of each guide structure 4 is located on the base circle a of the volute, ensuring that the starting position of each guide structure 4 is equidistant from the center of the impeller 3, thus guaranteeing a uniform circumferential distribution of multiple guide structures 4. Second, since the air inlet of the guide structure 4 is located at the base circle a, near the outlet of the impeller 3, it can promptly divert the airflow ejected by the impeller 3, preventing the formation of a concentrated high-speed airflow zone before the airflow enters the guide structure 4. Third, if the starting point of the guide structure 4 is located on a circle with a smaller radius than the base circle a (i.e., closer to the outer edge of the impeller 3), the airflow velocity at the outlet of the impeller 3 will be very high. The closer the starting point is to the impeller 3, the smaller the radial gap between them. The high-speed airflow will directly and violently impact the leading edge of the guide structure 4, generating strong pressure pulsations, leading to increased high-frequency noise. Furthermore, the airflow is prone to separation after the impact, forming local vortices and increasing flow losses. Furthermore, if the starting point of the flow guiding structure 4 is located on a circle with a radius larger than that of the base circle a (i.e., far away from the impeller 3), although the impact is reduced, the space of the volute is limited. Moving the starting point outward means that the arc length or flow channel length of the flow guiding structure 4 from the starting point to the end point is reduced, the airflow cannot be fully guided, the flow guiding effect is significantly reduced, and the flow from the impeller 3 outlet to the volute outlet 13 cannot be effectively organized.

[0113] In summary, the centrifugal fan of the present invention, by setting guide fins 2 at the air outlet 13, allows the airflow generated by the impeller 3 to be rectified by the guide fins 2 and discharged evenly, effectively reducing the outlet turbulence intensity and noise, and improving the overall performance of the centrifugal fan.

[0114] The centrifugal fan of this invention was tested and compared with the centrifugal fan of the prior art. The test data are as follows:

[0115] Therefore, it can be seen that the centrifugal fan with the present invention has better overall air performance and noise parameters than the centrifugal fan of the prior art.

[0116] The present invention also provides a range hood, which includes the centrifugal fan mentioned above, further alleviating the technical problem in the prior art that the uneven airflow distribution caused by the uneven space near the air outlet of the volute leads to eddies and wind noise, effectively ensuring that the airflow velocity is uniform at the air outlet and preventing the generation of eddies and wind noise.

[0117] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0118] The specific embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A centrifugal fan, characterized in that, Including the volute and impeller (3); The volute includes two side plates (11) and a surrounding plate (12) disposed between the two side plates (11). The surrounding plate (12) and the two side plates (11) together form an inner cavity and an air outlet (13) communicating with the inner cavity. The impeller (3) is disposed in the inner cavity, and a plurality of parallel guide fins (2) are arranged sequentially at intervals near the air outlet (13) in the inner cavity. The two ends of the guide fins (2) are respectively connected to the two side plates (11), and a first guide air duct (29) is formed between adjacent guide fins (2) and between the guide fins (2) and the surrounding plate (12) to guide the airflow of the inner cavity to the air outlet (13). Among them, from the side near the volute tongue in the volute to the side away from the volute tongue, along the axis of the impeller (3), the distance between the end of each guide fin (2) away from the air outlet (13) and the air outlet surface of the air outlet (13) gradually increases in the projection of each guide fin (2).

2. The centrifugal fan according to claim 1, characterized in that, Along the radial direction of the impeller (3), in the projection of the guide fins (2), the minimum distance between the end away from the air outlet (13) and the outer ring profile of the impeller (3) is not less than the volute tongue gap of the volute.

3. The centrifugal fan according to claim 2, characterized in that, On a cross section perpendicular to the axis of the impeller (3), the volute has a base circle (a) and a first reference line (b). The center point (5) of the arc of the volute tongue is located on the first reference line (b), and the first reference line (b) is tangent to the base circle (a). Along the axis of the impeller (3), the end of each guide fin (2) that is far from the air outlet (13) is located on the first reference line (b).

4. The centrifugal fan according to any one of claims 1-3, characterized in that, The guide fin (2) includes an air outlet (24), which is located on the air outlet surface of the air outlet (13), and the air outlets (24) of each guide fin (2) are evenly distributed on the air outlet surface, thus dividing the air outlet surface evenly.

5. The centrifugal fan according to claim 4, characterized in that, Along the opposite direction of the spiral direction (d) of the profile of the volute, the volute includes a volute tongue guide (14) extending from the volute tongue to the air outlet (13) of the air outlet surface, and the profile of the volute tongue guide (14) is a smooth straight line. Along the axis of the impeller (3), the extension direction of the projection of the guide fin (2) is parallel to the extension direction of the profile of the volute near the air outlet (13) away from the volute tongue.

6. The centrifugal fan according to claim 4, characterized in that, In the opposite direction of the spiral direction (d) of the profile of the volute, the volute includes a volute tongue guide (14) extending from the volute tongue to the air outlet (13) air outlet surface. The profile of the volute tongue guide (14) includes a first straight segment (141) and a second straight segment (142) that are bent into each other. The first straight segment (141) is close to the air outlet (13) air outlet surface and takes the direction perpendicular to the air outlet (13) air outlet surface as the reference direction (e). The first straight segment (141) extends along the reference direction (e). The guide fin (2) includes a first guide section (21) and a second guide section (22). One end of the first guide section (21) is the air outlet (24), and the other end is connected to the second guide section (22). The first guide section (21) and the first straight segment (141) extend in the same direction.

7. The centrifugal fan according to claim 6, characterized in that, Along the axis of the impeller (3), the extension direction of the projection of the second guide section (22) is parallel to the extension direction of the profile of the volute near the air outlet (13) away from the volute tongue.

8. The centrifugal fan according to claim 6, characterized in that, From the side closer to the volute tongue to the side farther away from the volute tongue, the distance between the end of the first guide section (21) away from the air outlet end (24) and the air outlet surface of the air outlet (13) gradually increases.

9. The centrifugal fan according to claim 8, characterized in that, The first guide section (21) near the volute tongue and the first straight segment (141) are of equal length.

10. The centrifugal fan according to claim 9, characterized in that, On a cross section perpendicular to the axis of the impeller (3), the volute also has a second reference line (c). In the first guide section (21) near the volute tongue, the end away from the air outlet (24) and the midpoint of the first straight segment (141) are both located on the second reference line (c). In this case, the end of each of the first guide sections (21) that is away from the air outlet (24) is located at the second reference line (c).

11. The centrifugal fan according to any one of claims 1-3, characterized in that, The guide fin (2) is provided with a flow hole (25) that can connect to the adjacent first guide air duct (29), and the flow hole (25) is arranged in an array on the guide fin (2).

12. The centrifugal fan according to any one of claims 1-3, characterized in that, The guide fin (2) includes an air inlet end (23), which is located away from the air outlet (13). Along the width direction of the guide fin (2), the air inlet end (23) is a flow collection structure that gradually protrudes from both ends inward and away from the air outlet surface. The point farthest from the air outlet surface in the flow collection structure is the protrusion point (26). The impeller (3) has a middle disk (31) and a front disk (321) and a rear disk (322) respectively disposed on both sides of the middle disk (31). Along the width direction of the guide fin (2), the guide fin (2) includes a first side (2a) and a second side (2b) disposed opposite to each other. The first side (2a) is disposed near the front plate (321), and the second side (2b) is disposed near the rear plate (322). Along the axis of the impeller (3), the distance between the middle disk (31) and the front disk (321) is H1, the distance between the middle disk (31) and the rear disk (322) is H2, the distance between the protruding point (26) and the first side (2a) is h1, the distance between the protruding point (26) and the second side (2b) is h2, and H1 / H2=h1 / h2.

13. The centrifugal fan according to claim 12, characterized in that, The convex point (26) is located on the plane where the middle disk (31) is located.

14. The centrifugal fan according to claim 12, characterized in that, The air inlet end (23) of the guide fin (2) is provided with a plurality of diversion protrusions (27). The plurality of diversion protrusions (27) are arranged sequentially along the width direction of the guide fin (2), and along the width direction of the guide fin (2), each diversion protrusion (27) gradually protrudes from both ends inward toward the direction away from the air outlet surface.

15. The centrifugal fan according to any one of claims 1-3, characterized in that, The number of the flow guide fins (2) is 2-6.

16. The centrifugal fan according to any one of claims 1-3, characterized in that, The side plate (11) of the volute is provided with a plurality of flow guiding structures (4), and a second flow guiding duct (41) is formed between adjacent flow guiding structures (4) and between the flow guiding structure (4) and the enclosure plate (12). The second flow guiding duct (41) is connected to the air inlet side of a plurality of first flow guiding ducts (29) in a corresponding manner.

17. The centrifugal fan according to claim 16, characterized in that, The flow guiding structure (4) extends along the profile direction of the volute.

18. The centrifugal fan according to claim 16, characterized in that, The two ends of the guide fin (2) are bent to form a mounting plate (28); The two ends of the guide fin (2) are respectively mounted on the two side plates (11) via the mounting plate (28); and / or, the air outlet end of the guide structure (4) extends from the air inlet end (23) of the guide fin (2) to the air outlet (13) to form an extension section (42), the extension direction of the extension section (42) is the same as the extension direction of the guide fin (2), and the two ends of the guide fin (2) are respectively mounted on the extension section (42) on the two side plates (11) via the mounting plate (28).

19. The centrifugal fan according to claim 18, characterized in that, The air inlet end of the air guide structure (4) is tangent to the base circle (a) of the volute.

20. A range hood, characterized in that, Includes the centrifugal fan as described in any one of claims 1-19.

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