An oil fume exhaust fan

Abstract

The application discloses a kind of exhaust fume fans, including shell, double air inlet type wind wheel and air outlet pipe, shell includes volute and air inlet box, air inlet box two sides are equipped with half-ring type import jet cover, inside is equipped with the inclined flow guide plate with hole, flow guide plate inside is provided with multi-chamber resonance structure and composite sound-absorbing material;Wind wheel adopts circular arc blade with bevel structure, volute bottom is equipped with conical oil collecting groove, air outlet pipe is equipped with airfoil guide vane inside.By the synergistic effect of jet cover sound-absorbing layer, flow guide plate resonance noise reduction structure and composite sound-absorbing material, the comprehensive inhibition of high frequency, medium frequency and low frequency noise during fan operation is realized;Meanwhile, using oil-repellent and water-repellent coating, conical oil collecting groove and airfoil guide vane structure realize efficient oil fume delivery, oil stain separation collection and airflow rectification, improve exhaust fume efficiency, reduce operating noise and enhance long-term operation stability.

Description

Technical Field

[0001] This invention relates to the field of kitchen exhaust fan technology, specifically to a kitchen exhaust fan. Background Technology

[0002] Kitchen exhaust fans are core power equipment in kitchen fume purification systems, commercial fume extraction equipment, and industrial fume treatment devices. Their main function is to quickly extract oily fumes generated during cooking, heating, or production processes and exhaust them outdoors, thereby improving the working environment and reducing the pollution of equipment and space caused by oily fumes. With the large-scale development of the catering industry and the increasing demands of users for quiet operation, energy saving, and ease of maintenance, kitchen exhaust fans not only need to have high exhaust efficiency but also need to take into account comprehensive performance such as noise control, oil-sludge separation, and long-term stable operation.

[0003] Most existing kitchen exhaust fans use ordinary centrifugal impellers with volute structures for airflow. During operation, the airflow easily generates turbulence, vortices, and airflow pulsation as it passes through the air inlet, impeller, and volute channel, resulting in significant aerodynamic noise. Simultaneously, the blade passage noise generated by the periodic cutting of the airflow by the impeller blades continuously propagates outwards, leading to high overall fan noise. While some products attempt to reduce noise by adding sound-absorbing cotton or sound insulation layers, these structures primarily target mid-to-high frequency noise, offering limited absorption of low-to-mid frequency noise generated during fan operation, thus limiting their noise reduction capabilities.

[0004] In view of this, we will study and improve the existing problems to provide an exhaust fan to solve the current problems. The aim of this technology is to reduce the operating noise of the fan, improve the efficiency of oil fume transportation, enhance the oil collection capacity, and improve the practical value of the equipment. Summary of the Invention

[0005] The present invention aims to solve the problems of large airflow turbulence noise, difficulty in effectively suppressing low and medium frequency noise, easy adhesion and accumulation of oil stains, and decreased exhaust efficiency after long-term operation of existing exhaust fans. The invention provides an exhaust fan that improves the fan's noise reduction capability, oil fume conveying capacity, and long-term operational stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A range hood includes a housing, a dual-inlet impeller installed within the housing, and an outlet pipe connected to the housing outlet. The housing includes a volute and an air inlet box located above the volute. The air inlet box has symmetrical semi-annular inlet shrouds on both sides, with the inlet of the shrouds having a smooth, rounded transition, and the inner wall of the shrouds is provided with a thin layer of porous sound-absorbing composite material. The impeller includes several arc-shaped blades, with the inlet edges of the blades having a beveled structure. The bottom of the volute has a conical oil collection groove. The air inlet box contains multiple perforated inclined guide plates, and the guide plates have a multi-chamber resonant structure inside.

[0007] Specifically, a semi-annular inlet shroud is used to smoothly guide the airflow into the fan, reducing the probability of airflow separation and vortex formation in the inlet area; at the same time, a guide vane is used to rectify and distribute the airflow, making the airflow entering the impeller area more uniform and stable; and a multi-chamber resonant structure is used to absorb the low- and medium-frequency noise generated during the operation of the fan, thereby improving the overall noise reduction effect.

[0008] In a preferred embodiment, the thin porous sound-absorbing composite material layer on the inner wall of the shroud has a thickness of 0.5 to 2 mm, and the thin porous sound-absorbing composite material layer is made of a composite material of polyester fiber and activated carbon.

[0009] Specifically, porous sound-absorbing materials are used to absorb high-frequency airflow noise generated in the inlet area, while activated carbon materials can improve the adsorption capacity of odor components in the oil fume gas, thereby improving the operating environment of the fan.

[0010] In a preferred embodiment, the wind turbine is further configured such that: the wind turbine consists of 55 arc-shaped blades, the beveled edge of the blade inlet has a beveled angle of 23.5°, and the beveled depth accounts for 12% of the blade length.

[0011] Specifically, the oblique cutting structure at the blade inlet edge reduces the impact loss when the airflow enters the impeller, weakens the pulsation phenomenon caused by the blade cutting the airflow, improves the aerodynamic performance of the wind turbine, and reduces operating noise.

[0012] In a preferred embodiment, the guide plate is further configured such that: the surface of the guide plate has a plurality of small holes, the multi-chamber resonant structure includes 3 to 6 Helmholtz resonant cavities, each resonant cavity is connected to the small holes on the surface of the guide plate through a neck channel, the length of the neck channel is 8 to 12 mm, the cavity volume is 500 to 3000 mm³, and the resonant frequency is tuned according to the passing frequency of the wind turbine blades.

[0013] Specifically, by matching the resonant frequency to the main noise frequency band during wind turbine operation, the resonant cavity can resonate and absorb noise at specific frequencies, thereby improving the attenuation effect of low and medium frequency noise.

[0014] In a preferred embodiment, the flow guide plate is further configured such that: the interior of the flow guide plate is filled with a composite sound-absorbing material, the composite sound-absorbing material comprising polyester fiber and activated carbon, wherein the polyester fiber accounts for 70% to 85% by mass and the activated carbon accounts for 15% to 30% by mass, and the activated carbon is subjected to fluorination or silane oleophobic surface modification treatment; a nano-oleophobic coating and an oleophobic microporous membrane are provided on the inner side of the small holes on the surface of the flow guide plate.

[0015] Specifically, wideband noise reduction is achieved through the synergistic effect of composite sound-absorbing materials and resonant structures, while the oleophobic structure prevents oil fumes from entering the interior of the sound-absorbing materials, thus improving the long-term reliability of the sound-absorbing components.

[0016] In a preferred embodiment, the composite sound-absorbing material is further configured such that a pure polyester fiber protective layer with a thickness of 0.5 to 1 mm is wrapped around its exterior, and the surface of the guide plate is covered with a composite sound-absorbing coating or layer of polyester fiber and activated carbon.

[0017] Specifically, a protective layer is used to isolate and protect the sound-absorbing material, reducing the risk of direct adhesion of oil stains and further improving the sound absorption capacity of the deflector surface.

[0018] In a preferred embodiment, the air outlet duct is further configured such that it is inclined upward at 10° relative to the horizontal direction, and the air outlet duct is provided with a plurality of airfoil-shaped guide vanes, the surface of which is coated with a nano-oleophobic coating.

[0019] Specifically, the airflow output from the wind turbine is rectified by airfoil guide vanes, converting some of the dynamic pressure into static pressure, thereby improving exhaust efficiency and reducing airflow disturbance and additional noise in the exhaust area.

[0020] In a preferred embodiment, the conical oil collecting groove is further configured such that it is formed by the downward convergence of the bottom of the volute towards the center, and an oil drain port is provided at the lowest point of the conical oil collecting groove.

[0021] Specifically, the grease particles in the fumes are thrown towards the inner wall of the volute by centrifugal force and flow into the oil collection tank along the oleophobic surface for centralized collection and discharge, thereby reducing the accumulation of oil.

[0022] In a preferred embodiment, the wind turbine blade surface and the inner wall of the volute are further configured such that a nano-oleophobic and hydrophobic coating is applied.

[0023] Specifically, by using a nano-oleophobic and hydrophobic coating, the adhesion between grease and structural surfaces is reduced, allowing oil to quickly collect and flow into the oil collection tank, thereby improving the long-term operational stability and maintenance convenience of the fan.

[0024] The beneficial effects achieved by this invention are as follows: 1. In this invention, a thin layer of porous sound-absorbing composite material is applied to the inner wall of the semi-annular inlet shroud on both sides of the air inlet box to effectively suppress the inlet vortex. Simultaneously, the perforated inclined guide plate inside the air inlet box utilizes a multi-chamber resonant structure combined with a composite sound-absorbing material of polyester fiber and modified activated carbon to achieve precise narrow-band absorption at the blade passage frequency, thus achieving broadband sound absorption. Testing shows that the overall operating noise of the fan in this invention is 6-10 dB lower than existing similar exhaust fans, with particularly outstanding noise reduction in the mid-to-low frequency range, significantly improving the user experience.

[0025] 2. In this invention, the use of arc-shaped blades and a 23.5° oblique cut structure at the inlet edge effectively reduces the impact loss at the blade inlet, improves the uniformity of air intake and work efficiency; combined with the 10° inclined design of the exhaust pipe and the rectification effect of the air-bladed guide vanes, the fan can obtain higher static pressure while maintaining high air volume, and the static pressure efficiency is significantly improved compared with traditional fans, resulting in better oil fume extraction effect.

[0026] 3. In this invention, the entire surface of the wind turbine blades and the inner wall of the volute are coated with a nano-oleophobic and hydrophobic coating, making it difficult for oil fumes to adhere; the conical oil collection groove at the bottom of the volute can quickly guide the oil to gather and be discharged; the small holes on the surface of the guide plate and the nano-oleophobic coating and protective layer on the outside of the composite sound-absorbing material effectively prevent the performance degradation caused by activated carbon adsorbing oil stains, and significantly extend the maintenance cycle and service life of the wind turbine.

[0027] 4. In this invention, the multi-stage flow guiding, rectification and noise reduction structure reduces airflow loss and turbulence; the oleophobic treatment of modified activated carbon combined with the multi-chamber resonant structure achieves efficient noise reduction without significantly increasing wind resistance; the combination of the conical oil collection groove and the nano-coating effectively prevents oil accumulation and reduces vibration and energy consumption during long-term operation of the fan. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present invention; Figure 2 This is a schematic diagram of the casing surface structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the wind turbine, jet shroud, and oil collection tank according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the wind turbine surface structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the air inlet box and guide plate structure according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a guide vane structure according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the cross-sectional structure of a guide plate according to an embodiment of the present invention.

[0029] Figure label: 1. Housing; 2. Impeller; 3. Air outlet duct; 4. Flow hood; 5. Oil collection tank; 6. Guide plate; 11. Volute; 12. Air inlet box; 21. Blade; 61. Multi-chamber resonant structure; 62. Composite sound-absorbing material. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0031] It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the invention.

[0032] The following describes, with reference to the accompanying drawings, some embodiments of the present invention, providing an exhaust fan.

[0033] Combination Figures 1-7 As shown, the present invention provides a fume extraction fan, comprising a housing 1, a dual-inlet impeller 2 installed inside the housing 1, and an outlet pipe 3 connected to the outlet of the housing 1. The housing 1 includes a volute 11 and an air inlet box 12 located above the volute 11. The dual-inlet impeller 2 forms a dual-side air intake structure, allowing the fume airflow to enter the fan from both sides simultaneously, improving the overall air intake capacity and fume extraction efficiency.

[0034] In this embodiment, symmetrical semi-annular inlet shrouds 4 are provided on both sides of the air inlet box 12, and the inlet of each shroud 4 has a smooth arc transition structure. The shrouds 4 are used to pre-guide the airflow entering the fan, so that the airflow can enter the fan smoothly and reduce airflow separation and vortex formation in the inlet area. Furthermore, a thin layer of porous sound-absorbing composite material is provided on the inner wall of the shroud 4. The thickness of the thin layer of porous sound-absorbing composite material is 0.5-2mm, and it is made of polyester fiber and activated carbon composite material. The polyester fiber is used to absorb high-frequency airflow noise, and the activated carbon is used to adsorb odor components in the oil fume gas, thereby improving the noise reduction effect in the inlet area.

[0035] refer to Figure 1 , Figure 3 and Figure 4As shown, in this embodiment, the wind turbine 2 adopts a dual-inlet structure, consisting of 55 arc-shaped blades 21, with each blade 21 evenly distributed around the outer periphery of the wind turbine 2 along the circumference. The inlet edge of each blade 21 has a beveled structure with a bevel angle of 23.5° and a bevel depth accounting for 12% of the blade 21's length. This beveled structure reduces the impact loss generated when airflow enters the blade 21, reduces airflow pulsation caused by the blades cutting the airflow, improves the aerodynamic efficiency of the wind turbine 2, and reduces operating noise.

[0036] In this embodiment, the entire surface of the blades 21 of the impeller 2 is coated with a nano-oleophobic and hydrophobic coating. The nano-oleophobic and hydrophobic coating can reduce the adhesion of grease particles to the surface of the blades 21, making it difficult for oil to accumulate on the impeller surface, thereby maintaining the dynamic balance performance and exhaust efficiency of the impeller 2 during long-term operation.

[0037] refer to Figure 2 and Figure 3 As shown, in this embodiment, the volute 11 is used to collect the high-speed airflow output by the impeller 2 and guide the airflow to the exhaust duct 3. The inner wall of the volute 11 is also coated with a nano-oleophobic and hydrophobic coating to reduce the amount of grease in the fumes adhering to the surface of the volute 11. A conical oil collecting groove 5 is provided at the bottom of the volute 11. The conical oil collecting groove 5 is formed by the downward convergence of the bottom of the volute 11 towards the center, and an oil outlet is provided at its lowest point. The grease particles in the fumes are thrown towards the inner wall of the volute 11 under the action of centrifugal force, and slide down the oleophobic surface into the conical oil collecting groove 5 for collection, and finally discharged through the oil outlet.

[0038] refer to Figures 5 to 7 As shown, in this embodiment, the air inlet box 12 is provided with a plurality of perforated inclined guide plates 6. Each guide plate 6 is arranged inclined along the air inlet direction and spaced apart to form a guide channel. The surface of the guide plate 6 is provided with a plurality of small holes, which are used to allow the airflow to form an acoustic coupling effect with the internal structure of the guide plate 6.

[0039] In this embodiment, a multi-chamber resonant structure 61 is provided inside the guide plate 6. The multi-chamber resonant structure 61 includes 3 to 6 Helmholtz resonant cavities, each of which is connected to a small hole on the surface of the guide plate 6 through a neck channel. The neck channel has a length of 8 to 12 mm, and the volume of each cavity is 500 to 3000 mm³. The resonant frequency of each resonant cavity is tuned according to the passing frequency of the impeller blades 2, thereby enabling directional absorption of low- and medium-frequency noise generated during wind turbine operation.

[0040] In this embodiment, the guide plate 6 is filled with a composite sound-absorbing material 62. The composite sound-absorbing material 62 includes polyester fiber and activated carbon, wherein the polyester fiber accounts for 70% to 85% of the mass, and the activated carbon accounts for 15% to 30% of the mass, and the activated carbon has undergone fluorination or silane oleophobic surface modification treatment. By combining the composite sound-absorbing material 62 with the multi-chamber resonant structure 61, broadband noise absorption and specific frequency band noise suppression can be achieved simultaneously.

[0041] In this embodiment, a nano-oleophobic coating and an oleophobic microporous membrane are provided on the inner side of the small holes on the surface of the guide plate 6 to prevent oil fumes from entering the interior of the guide plate 6. The composite sound-absorbing material 62 is wrapped with a pure polyester fiber protective layer with a thickness of 0.5-1mm to improve its anti-pollution ability and service life. At the same time, the surface of the guide plate 6 is covered with a composite sound-absorbing coating or lamination of polyester fiber and activated carbon to further enhance the sound absorption capacity of the surface of the guide plate 6.

[0042] refer to Figure 1 As shown, in this embodiment, the air outlet duct 3 is connected to the air outlet of the housing 1, and the air outlet duct 3 is inclined upward at 10° relative to the horizontal direction. Multiple airfoil-shaped guide vanes are installed inside the air outlet duct 3, and the surface of the guide vanes is coated with a nano-oleophobic coating. The airfoil guide vanes can rectify the rotating airflow output by the impeller 2, converting some dynamic pressure into static pressure, improving exhaust efficiency and reducing exhaust noise, while preventing oil stains from adhering and accumulating on the guide vane surface.

[0043] The working principle and usage process of this invention are as follows: After the fan starts, the oily fumes first enter the fan through the semi-annular inlet shrouds 4 on both sides of the inlet box 12. The shrouds 4 smoothly guide the incoming airflow and initially absorb the high-frequency airflow noise generated in the inlet area through the thin layer of porous sound-absorbing composite material on the inner wall. Subsequently, the airflow enters the inside of the inlet box 12 and flows through the guide channel formed by multiple inclined guide plates 6. During the guide process, the multi-chamber resonant structure 61 specifically absorbs the mid-to-low frequency noise generated by the fan operation, while the composite sound-absorbing material 62 further attenuates the broadband noise, thereby achieving noise reduction in the inlet area.

[0044] After rectification, the airflow enters evenly into the dual-inlet impeller 2. As the impeller 2 rotates, it accelerates and pressurizes the airflow, throwing it into the volute 11. Oil particles in the fumes gather on the inner wall of the volute 11 under centrifugal force and slide along the nano-oleophobic and hydrophobic coating to the conical oil collection trough 5 for collection and discharge. The high-pressure airflow then enters the outlet duct 3, where it is rectified and pressure restored by the airfoil guide vanes before being discharged outside the fan, thus completing the overall process of fume conveying, noise reduction, and oil separation.

[0045] In the description of this specification, the terms "one embodiment," "some embodiments," "specific 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.

[0046] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A fume exhaust fan, characterized in that, It includes a housing (1), a double-inlet impeller (2) installed inside the housing (1) and an air outlet pipe (3) connected to the air outlet of the housing (1). The housing (1) includes a volute (11) and an air inlet box (12) located above the volute (11). The air inlet box (12) is provided with symmetrical semi-annular inlet shrouds (4) on both sides. The inlet of the shroud (4) has a smooth arc transition, and the inner wall of the shroud (4) is provided with a thin layer of porous sound-absorbing composite material. The wind turbine (2) includes several arc-shaped blades (21), and the inlet edge of the blades (21) is provided with a beveled structure; A conical oil collection groove (5) is provided at the bottom of the volute (11); The air inlet box (12) is provided with multiple perforated inclined guide plates (6), and the guide plates (6) are provided with a multi-chamber resonant structure (61).

2. The exhaust fan according to claim 1, characterized in that, The thickness of the thin porous sound-absorbing composite material layer on the inner wall of the shroud (4) is 0.5-2 mm, and the thin porous sound-absorbing composite material layer is made of polyester fiber and activated carbon composite material.

3. The exhaust fan according to claim 1, characterized in that, The wind turbine (2) is composed of 55 arc-shaped blades (21). The oblique cutting angle of the oblique cutting structure at the inlet edge of the blade (21) is 23.5°, and the oblique cutting depth accounts for 12% of the length of the blade (21).

4. The exhaust fan according to claim 1, characterized in that, The guide plate (6) has multiple small holes on its surface. The multi-chamber resonant structure (61) contains 3 to 6 resonant cavities. Each resonant cavity is connected to the small holes on the surface of the guide plate (6) through a neck channel. The length of the neck channel is 8 to 12 mm, and the volume of the cavity is 500 to 3000 mm³. The resonant frequency is tuned according to the passing frequency of the wind turbine (2) blades.

5. The exhaust fan according to claim 1 or 4, characterized in that, The guide plate (6) has an airfoil-shaped cross section and is filled with a composite sound-absorbing material (62). The composite sound-absorbing material (62) includes polyester fiber and activated carbon. The polyester fiber accounts for 70% to 85% of the mass, and the activated carbon accounts for 15% to 30% of the mass. The activated carbon is treated with fluorination or silane oleophobic surface modification. The guide plate (6) has a nano-oleophobic coating and an oleophobic microporous membrane on the inner side of the small holes on its surface.

6. The exhaust fan according to claim 5, characterized in that, The composite sound-absorbing material (62) is wrapped with a pure polyester fiber protective layer with a thickness of 0.5 to 1 mm, and the surface of the guide plate (6) is covered with a composite sound-absorbing coating or a laminate of polyester fiber and activated carbon.

7. The exhaust fan according to claim 1, characterized in that, The air outlet pipe (3) is inclined upward at 10° relative to the horizontal direction, and multiple airfoil-shaped guide vanes are provided inside the air outlet pipe (3), with the surface of the guide vanes coated with a nano oleophobic coating.

8. The exhaust fan according to claim 1, characterized in that, The conical oil collecting groove (5) is formed by the bottom of the volute (11) tilting downwards towards the center, and an oil drain is provided at the lowest point of the conical oil collecting groove (5).

9. The exhaust fan according to claim 1, characterized in that, The surface of the blades (21) of the wind turbine (2) and the inner wall of the volute (11) are coated with a nano-oleophobic and hydrophobic coating.

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