A pre-rotating air inlet ring, a centrifugal fan, and a range hood

Abstract

This invention provides a pre-rotating air inlet ring, a centrifugal fan, and a range hood, belonging to the field of kitchen appliance technology. The pre-rotating air inlet ring includes an outer fixed ring, an inner fixed ring, and multiple blades; the outer and inner fixed rings are concentric and coaxially arranged; multiple blades are distributed between the outer and inner fixed rings, with the inner end of each blade fixedly connected to the inner fixed ring and the outer end fixedly connected to the outer fixed ring; the extension direction of the blades forms an acute angle with the perpendicular line to the axis of the outer fixed ring, i.e., the pre-rotation angle; the annular area is divided into three fan-shaped areas with successively increasing pre-rotation angles (α1<α2<α3) and successively decreasing blade spacing angles (β1>β2>β3). This achieves differentiated and gradient guidance of the inlet airflow in the circumferential direction.

Description

Technical Field

[0001] This invention relates to the field of kitchen appliance technology, and in particular to a pre-rotating air inlet ring, a centrifugal fan, and a range hood. Background Technology

[0002] As an indispensable household appliance in modern kitchens, the core function of a range hood is to efficiently capture and remove cooking fumes, steam, and odors generated during cooking, thereby ensuring a clean and healthy indoor air environment. Currently, the vast majority of range hoods use centrifugal fans as their core power component. Centrifugal fans use a high-speed rotating impeller to perform work on the gas, giving it kinetic and pressure energy, which is then guided to the exhaust vent through a volute-like flow channel. This structure has advantages such as high air pressure, compact design, and strong adaptability, and is widely used in various kitchen exhaust systems.

[0003] However, in actual use, especially under conditions of high airflow or high back pressure in the common flue, centrifugal fans are prone to entering an unstable operating region, producing an aerodynamic instability phenomenon known as "surge." Surge manifests as periodic low-frequency pressure fluctuations, violent flow oscillations, and noticeable "whooshing" or roaring noises; in severe cases, it can even be accompanied by whole-machine vibration. From a fluid dynamics perspective, the essence of surge is that the airflow undergoes large-scale flow separation at the impeller inlet, causing some of the discharged gas to flow back to the impeller inlet due to excessive pressure, thus triggering a chain reaction of airflow pulsations and repeated energy exchanges. In addition, if the radius of curvature of the volute tongue at the volute outlet is too large or too small, it will also exacerbate the separation and vortex shedding of the airflow in the outlet area, further inducing pressure pulsations, forming a positive feedback mechanism, and causing the surge phenomenon to persist or even worsen.

[0004] Surge not only severely impacts user auditory comfort and causes significant noise pollution, but it also generates alternating loads on the mechanical structure of the fan system, accelerating fatigue damage to motor bearings, impeller blades, and volute connections, and drastically shortening the overall lifespan of the unit. More critically, in densely populated high-rise residential environments, the resistance of the public flue dynamically changes with floor height and usage time, causing the range hood to frequently approach the critical surge boundary, making stability issues particularly prominent. Therefore, effectively suppressing or eliminating surge in centrifugal fans under high-load conditions has become a pressing technical challenge for the industry. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a range hood that effectively suppresses centrifugal fan surge and reduces aerodynamic noise by optimizing the inlet pre-swirl and outlet volute structure.

[0006] A first aspect of the present invention provides a pre-rotating air inlet ring, comprising an outer fixed ring, an inner fixed ring, and a plurality of blades; The outer fixing ring and the inner fixing ring are concentric and coaxially arranged; The plurality of blades are distributed between the outer fixing ring and the inner fixing ring, with the inner end of each blade fixedly connected to the inner fixing ring and the outer end fixedly connected to the outer fixing ring; The extension direction of the blade forms an acute angle with the perpendicular line of the axis of the outer fixing ring, i.e., the pre-rotation angle. The annular region between the outer fixing ring and the inner fixing ring is divided into at least three sequentially adjacent sector regions, namely the first region, the second region and the third region; The pre-rotation angle in the first region is α1, the pre-rotation angle in the second region is α2, and the pre-rotation angle in the third region is α3, and α1 < α2 < α3 is satisfied.

[0007] Furthermore, in the first region, the angle between the extension directions of two adjacent blades is β1; in the second region, the angle between the extension directions of two adjacent blades is β2; and in the third region, the angle between the extension directions of two adjacent blades is β3, and β1>β2>β3 are satisfied.

[0008] A second aspect of the present invention provides a centrifugal fan, comprising a spiral housing and an impeller installed inside the housing, wherein the housing is provided with an air inlet and an air outlet, and a pre-rotating air inlet ring as described above is installed at the air inlet.

[0009] Furthermore, it also includes the worm tongue assembly; A protrusion is provided on the inner wall of the housing near the air outlet; The volute tongue assembly is disposed on the protrusion, the inner surface of the volute tongue assembly is in close contact with the surface of the protrusion, and the outer surface of the volute tongue assembly is a smooth curved surface.

[0010] Furthermore, the outer surface of the volute tongue assembly includes a continuous first arcuate segment and a first straight segment; The first arc-shaped segment is disposed on the protrusion; The first straight segment is close to the air inlet.

[0011] Furthermore, the radius of the circle containing the arc segment is greater than the radius of the circle containing the protrusion.

[0012] Furthermore, the cochlear tongue assembly includes at least an inner cochlear tongue and an outer cochlear tongue; The inner surface of the inner spiracle is in close contact with the surface of the protrusion; The outer surface of the inner cochlear tongue is in close contact with the inner surface of the outer cochlear tongue; The outer surface of the external spiracle is a smooth curved surface.

[0013] Furthermore, the outer surface of the inner cochlear tongue includes a continuous second arcuate segment and a second straight segment; The radius of the circle containing the second arc segment is smaller than the radius of the circle containing the protrusion.

[0014] Furthermore, the outer end of the volute assembly extends to the air outlet.

[0015] A third aspect of the present invention provides a range hood, including a centrifugal fan as described in the above technical solution.

[0016] The present invention has the following advantages or beneficial effects: 1. Pre-swirl inlet ring: By setting multiple guide vanes with specific tilt angles between the outer and inner fixed rings, and dividing the annular region into three fan-shaped areas with progressively increasing pre-swirl angles (α1<α2<α3) and progressively decreasing blade spacing angles (β1>β2>β3), differentiated and gradient guidance of the inlet airflow in the circumferential direction is achieved. This structure allows the airflow to obtain a tangential velocity component consistent with the impeller rotation direction on the basis of axial flow, forming effective pre-swirl, significantly reducing the impact angle and flow separation risk when the airflow enters the impeller channel; at the same time, the non-uniform blade distribution strategy optimizes the uniformity of the circumferential pressure field, avoiding local airflow congestion or vortex concentration, thereby improving the impeller's working efficiency from the source and reducing energy loss and high-frequency noise sources in the inlet section.

[0017] 2. A detachable volute tongue assembly is installed on the inner wall of the casing near the air outlet. This assembly fits tightly against the surface of the original protrusion (i.e., the original volute tongue base) and has a smooth outer curved surface. This substantially increases the effective radius of curvature of the volute tongue and optimizes the geometry of the outlet flow channel without altering the main structure of the volute casing. This design significantly improves the flow continuity of the high-speed airflow ejected from the impeller as it turns and merges into the air outlet, effectively mitigating boundary layer separation, vortex shedding, and periodic pressure pulsations caused by abrupt changes in the flow cross-section or excessive curvature. Simultaneously, by reducing the local cross-sectional area of ​​the outlet, it suppresses the tendency for airflow backflow under high back pressure conditions, weakening the physical causes of surge. Attached Figure Description

[0018] The above and other features and advantages of the present invention will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of a pre-rotating air inlet ring according to an exemplary embodiment; Figure 2 This is a schematic diagram of the pre-rotation angle of a pre-rotation air inlet ring according to an exemplary embodiment; Figure 3This is a schematic diagram of the structure of a centrifugal fan according to an exemplary embodiment; Figure 4 This is a schematic diagram of a centrifugal fan without structural separation, according to an exemplary embodiment. Figure 5 yes Figure 4 Enlarged view of part A in the image.

[0020] The reference numerals in the attached figures are explained as follows: 1. Pre-rotating air inlet ring; 2. Housing; 3. Impeller; 4. Volute assembly; 11. Outer retaining ring; 12. Inner retaining ring; 13. Blade; 41. First arc segment; 42. First straight segment; 43. Inner cochlea; 44. Outer cochlea; 45. Second arc segment; 46. Second straight segment. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0022] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended meaning of inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.

[0023] Figure 1 This is a schematic diagram of a pre-rotating air inlet ring according to an exemplary embodiment; Figure 2 This is a schematic diagram of the pre-rotation angle of a pre-rotation air inlet ring according to an exemplary embodiment; Figure 3 This is a schematic diagram of the structure of a centrifugal fan according to an exemplary embodiment; Figure 4 This is a schematic diagram of a centrifugal fan without structural separation, according to an exemplary embodiment. Figure 5 yes Figure 4 Enlarged view of part A in the diagram. The above schematic diagram is only to illustrate the structural relationships related to the inventive point and is not intended as an actual scale of the product.

[0024] This invention relates to a centrifugal fan for a range hood and its aerodynamic components, specifically including a pre-swirling air inlet ring 1 with a non-uniform blade distribution structure, a modularly installable volute assembly 4, and a complete system composed of the above components. This technical solution effectively improves the stability of the internal flow field of the fan by introducing directional pre-swirling airflow at the air inlet and optimizing the volute geometry at the air outlet, significantly reducing aerodynamic noise, suppressing surge, and improving overall operating efficiency and user experience.

[0025] Example 1 like Figure 1 and Figure 2 As shown, this invention provides a pre-swirl inlet ring. The pre-swirl inlet ring 1 has an overall annular structure, consisting of an outer fixed ring 11, an inner fixed ring 12, and multiple guide vanes 13. The outer fixed ring 11 and the inner fixed ring 12 are concentric and coaxially arranged, forming a continuous annular channel space between them, used to guide external air into the pre-treatment stage before it enters the fan impeller 3. Multiple guide vanes 13 are distributed circumferentially within this annular space. One end of each vane 13 is connected to the inner fixed ring 12, and the other end is connected to the outer fixed ring 11, forming a stable mechanical support structure. All vanes 13 are inclined in the same direction, and their extension direction forms an acute angle with the vertical line of the axis of the outer fixed ring 11, which is the pre-swirl angle. The purpose of this pre-swirl angle is to allow the airflow to obtain a tangential velocity component consistent with the rotation direction of the impeller 3 before entering the impeller 3, thereby achieving the "pre-swirl" effect and improving the aerodynamic conditions at the airflow inlet.

[0026] Specifically, the annular region of the pre-swirl inlet ring 1 is divided into at least three sequentially adjacent fan-shaped regions, namely the first region, the second region, and the third region. These three regions are arranged continuously on the circumference, collectively covering the entire circumferential range of the inlet. Within each region, the pre-swirl angle of the guide vanes 13 is different: the pre-swirl angle in the first region is denoted as α1, the pre-swirl angle in the second region is denoted as α2, and the pre-swirl angle in the third region is denoted as α3, satisfying α1 < α2 < α3. In a preferred embodiment, α1 is set to 50 degrees, α2 to 60 degrees, and α3 to 70 degrees, exhibiting a gradual change trend from low to high. This design allows the airflow to experience different degrees of tangential acceleration as it passes through different regions, thereby achieving a more uniform pressure distribution and smoother velocity vector changes throughout the entire circumference.

[0027] Furthermore, the included angle of extension direction between two adjacent guide vanes 13 varies in each region. Specifically, the included angle between adjacent vanes 13 is β1 in the first region, β2 in the second region, and β3 in the third region, satisfying β1>β2>β3. In this embodiment, β1 is 12 degrees, β2 is 10 degrees, and β3 is 8 degrees. This means that the density of the vanes 13 gradually increases from the first region to the third region, thereby applying different flow splitting intensities to the airflow in different directions. This non-uniform distribution strategy can effectively avoid the generation of vortices caused by local airflow concentration, while enhancing the adaptability to complex incoming flows.

[0028] When the range hood is started, outside air first enters the pre-swirling air inlet ring 1. Due to the inclined arrangement of the blades 13, the airflow is given a tangential component in the same direction as the rotation of the impeller 3 while moving axially, forming a pre-swirling effect. This process not only reduces the impact loss when the airflow enters the impeller 3, but also improves the working efficiency of the impeller 3. Experimental data shows that, under the same motor power conditions, the turbulence intensity is significantly reduced and the noise source is suppressed after adopting this pre-swirling air inlet ring 1.

[0029] The core function of the pre-swirling air inlet ring 1 is that when the range hood is started, the outside air first flows through the pre-swirling air inlet ring 1. Due to the specific tilt angle and non-uniform distribution characteristics of the guide vanes 13, the airflow, which is originally mainly axial, is given a tangential velocity component in the same direction as the rotation of the impeller 3 when passing through the gap of the vanes 13, thus forming "pre-swirling". The direction of this pre-swirling airflow is highly matched with the relative velocity direction at the inlet of the impeller 3, thereby significantly reducing the impact loss and flow separation phenomenon when the airflow enters the impeller 3 flow channel.

[0030] Example 2 like Figures 3 to 5 As shown, the present invention also provides a centrifugal fan, the main structure of which includes a spiral housing 2 (i.e., a volute) and an impeller 3 installed inside the housing 2. The housing 2 is provided with an air inlet and an air outlet, wherein the air inlet is located on one axial side of the impeller 3, and the air outlet is located at the lateral end of the volute. At the air inlet, a pre-rotating air inlet ring 1 as described in Embodiment 1 is installed, making it a front-end guide device for the fan's air intake system.

[0031] In addition, the centrifugal fan also includes a specially designed volute tongue assembly 4. The volute tongue of a traditional centrifugal fan is usually a one-piece molded protrusion on the inner wall of the volute casing, located near the air outlet, used to guide airflow and prevent backflow. However, the curvature radius of a traditional volute tongue is fixed, making it difficult to adapt to the flow requirements under different operating conditions, and it is prone to causing airflow separation, periodic pressure pulsation, and even surge under high flow or high back pressure conditions.

[0032] To address the aforementioned issues, this invention provides an initial protrusion on the inner wall of the housing 2 near the air outlet. This protrusion is the traditional volute tongue base, and its outline is typically an arc with a radius of curvature denoted as R0. In this embodiment, R0 is 14 mm. Furthermore, this invention adds a separately manufactured volute tongue assembly 4, which covers and fits onto the surface of the initial protrusion.

[0033] The inner surface of the volute tongue assembly 4 fits perfectly against the outer surface of the original protrusion, ensuring no gaps or misalignment after installation. Its outer surface is designed as a smooth curve to contact and guide the high-speed exhaust airflow towards the outlet. For ease of installation and replacement, the volute tongue assembly 4 can integrate various fixing structures. For example, mounting ears with screw holes can be provided on the edge of the assembly for fixing to the volute housing; alternatively, a snap-fit ​​structure can be designed for quick insertion; or high-strength structural adhesive can be used for bonding. This modular design allows for low-cost upgrades to existing products without modifying the original volute housing mold.

[0034] In a preferred embodiment, the outer surface of the volute tongue assembly 4 is composed of a continuous first arc-shaped segment 41 and a first straight segment 42. The first arc-shaped segment 41 covers the original protrusion and undertakes the main airflow guiding function; the first straight segment 42 extends towards the air outlet, playing a transition and stabilizing role. More importantly, the radius of curvature of the circle containing the first arc-shaped segment 41 is greater than the radius of curvature of the circle containing the original protrusion. In this embodiment, the radius of curvature R2 of the first arc-shaped segment 41 is 16 mm, which is greater than R0 = 14 mm, thereby substantially increasing the effective radius of curvature of the volute tongue, making the change in the flow cross-section of the airflow more gradual during the turning process, and avoiding boundary layer separation and vortex shedding caused by sharp turns.

[0035] Furthermore, this invention proposes a double-layer volute tongue structure. The volute tongue assembly 4 comprises at least two parts: an inner volute tongue 43 and an outer volute tongue 44. The inner volute tongue 43 is directly attached to the surface of the original protrusion, and its outer surface serves as the mounting base for the outer volute tongue 44; the outer volute tongue 44 is fitted over the inner volute tongue 43, and its outer surface forms the guide surface that ultimately contacts the airflow. The advantages of this double-layer structure are: firstly, by combining inner and outer volute tongues 44 of different thicknesses or curvatures, it can flexibly adapt to the performance requirements of various models; secondly, the inner volute tongue 43 can serve as a universal base, while the outer volute tongue 44 serves as a functional adjustment component, achieving a "one base, multiple uses" product strategy and reducing development and inventory costs.

[0036] Specifically, the outer surface of the inner volute tongue 43 is also composed of a continuous second arc-shaped segment 45 and a second straight segment 46. It is noteworthy that the radius of curvature R1 of the circle containing the second arc-shaped segment 45 is 18 mm, which is larger than the original protrusion's R0 = 14 mm, and also larger than the outer volute tongue 44's R2 = 16 mm. This design allows for the selection of either the volute tongue assembly 4 or the inner volute tongue 43 to be mounted on the protrusion surface, depending on the model and power, to suppress high-frequency noise and surge.

[0037] Furthermore, the outer end of the volute assembly 4 is designed to extend close to the air outlet, even partially covering the air outlet inlet area. This extended design effectively increases the controlled path length of the airflow in the outlet section, allowing the high-speed jet to be fully rectified before entering free space, reducing the instability of the outlet jet, and thus further reducing radiated noise.

[0038] Example 3 This invention also provides a range hood. The range hood integrates the centrifugal fan described in Embodiment 2 above, making it particularly suitable for Chinese cooking scenarios requiring high static pressure and large air volume. In actual operation, the airflow first passes through the pre-rotating inlet ring 1 to achieve pre-rotation in the same direction as the impeller 3, realizing low-disturbance air intake; then it is accelerated and pressurized in the impeller 3; finally, it flows through the optimized volute assembly 4, smoothly converging into the outlet under the guidance of a gentle curved surface. Throughout the process, the inlet pre-rotation and outlet stabilization create a synergistic effect, significantly widening the stable operating range of the fan.

[0039] Laboratory tests were conducted, as detailed in the table below. Under the same airflow conditions, the prototype using the technical solution of this invention not only effectively improves aerodynamic noise compared to traditional fans, but also fundamentally suppresses the surge mechanism, greatly enhancing the reliability and user comfort of the range hood in complex kitchen environments.

[0040] In summary, this invention innovatively combines the non-uniform pre-rotating inlet ring 1 with the modular volute assembly 4 to construct a complete aerodynamic optimization system. This system balances structural feasibility, manufacturing economy, and superior performance, making it suitable for various household and commercial centrifugal fan products, and possessing broad industrialization prospects and significant technological advancement value.

[0041] In this embodiment of the invention, the term "multiple" refers to two or more, unless otherwise explicitly defined. The terms "install," "connect," and "fix" should be interpreted broadly. For example, "connect" can mean a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention based on the specific circumstances.

[0042] In the description of the embodiments of the present invention, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0043] In the description of this specification, the terms "an embodiment," "a preferred embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. For those skilled in the art, the embodiments of the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of the present invention should be included within the protection scope of the embodiments of the present invention.

Claims

1. A pre-rotating air inlet ring, characterized in that, It includes an outer fixing ring (11), an inner fixing ring (12), and multiple blades (13); The outer fixing ring (11) and the inner fixing ring (12) are concentric and coaxially arranged; The plurality of blades (13) are distributed between the outer fixing ring (11) and the inner fixing ring (12), with the inner end of each blade (13) fixedly connected to the inner fixing ring (12) and the outer end fixedly connected to the outer fixing ring (11); The extension direction of the blade (13) forms an acute angle with the perpendicular line of the axis of the outer fixing ring (11), that is, the pre-rotation angle; The annular region between the outer fixing ring (11) and the inner fixing ring (12) is divided into at least three sequentially adjacent sector regions, namely the first region, the second region and the third region; The pre-rotation angle in the first region is α1, the pre-rotation angle in the second region is α2, and the pre-rotation angle in the third region is α3, and α1 < α2 < α3 is satisfied.

2. The pre-rotating air inlet ring according to claim 1, characterized in that, In the first region, the angle between the extension directions of two adjacent blades (13) is β1; in the second region, the angle between the extension directions of two adjacent blades (13) is β2; and in the third region, the angle between the extension directions of two adjacent blades (13) is β3, and β1>β2>β3 are satisfied.

3. A centrifugal fan, comprising a spiral housing (2) and an impeller (3) mounted within the housing (2), characterized in that: The housing (2) is provided with an air inlet and an air outlet, and a pre-rotating air inlet ring (1) as described in claim 1 or 2 is installed at the air inlet.

4. A centrifugal fan according to claim 3, characterized in that, It also includes the cochlear tongue assembly (4); The inner wall of the housing (2) is provided with a protrusion near the air outlet; The volute tongue assembly (4) is disposed on the protrusion, the inner surface of the volute tongue assembly (4) is in close contact with the surface of the protrusion, and the outer surface of the volute tongue assembly (4) is a smooth curved surface.

5. A centrifugal fan according to claim 4, characterized in that, The outer surface of the volute assembly (4) includes a continuous first arc segment (41) and a first straight segment (42); The first arc-shaped segment (41) is disposed on the protrusion; The first straight segment (42) is close to the air inlet.

6. A centrifugal fan according to claim 5, characterized in that, The radius of the circle containing the arc segment is greater than the radius of the circle containing the protrusion.

7. A centrifugal fan according to any one of claims 4 to 6, characterized in that, The cochlear tongue assembly (4) includes at least an inner cochlear tongue (43) and an outer cochlear tongue (44); The inner surface of the inner volute (43) is in close contact with the surface of the protrusion; The outer surface of the inner cochlear tongue (43) is in close contact with the inner surface of the outer cochlear tongue (44); The outer surface of the external volute (44) is a smooth curved surface.

8. A centrifugal fan according to claim 7, characterized in that, The outer surface of the inner spiracle (43) includes a continuous second arcuate segment (45) and a second straight segment (46); The radius of the circle containing the second arc segment (45) is smaller than the radius of the circle containing the protrusion.

9. A centrifugal fan according to claim 4, characterized in that, The outer end of the volute assembly (4) extends to the air outlet.

10. A range hood, characterized in that, Including the centrifugal fan as described in any one of claims 4 to 9.

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