A fan and a range hood

Abstract

This utility model relates to a fan, including a volute and an impeller disposed within the volute. The impeller includes multiple blades with an arc-shaped radial cross-section arranged circumferentially, forming airflow channels between adjacent blades. A slit extending axially is formed on each blade near its radially inner side. This fan can eliminate localized negative pressure areas in the airflow channels between the blades, reduce eddies, and lower noise. This utility model also relates to a range hood, including the aforementioned fan.

Description

Technical Field

[0001] This utility model relates to a fan, and also to a range hood that uses the fan. Background Technology

[0002] Range hoods have become an indispensable kitchen appliance in modern homes. They operate on the principles of fluid dynamics, using a centrifugal fan installed inside to draw in and exhaust cooking fumes. The centrifugal fan consists of a casing, an impeller housed within the casing, and a motor that drives the impeller. As the impeller rotates, a negative pressure is generated at the center of the fan, drawing in the cooking fumes from below. After being accelerated by the fan, the fumes are collected by the casing and guided outwards.

[0003] To reduce the risk of users bumping their heads and to improve the aesthetics of a slim design, existing range hoods are beginning to use slim fans. For example, Chinese invention patent CN113310085B (application number 202110586605.3) and Chinese utility model patent CN215863629U (application number 202122053725.5) both disclose range hoods that use slim fans.

[0004] Thin-type fans, due to their reduced thickness, have relatively narrow air intake spaces at the inlet. The presence of the inlet panel increases turbulence, and the close distance between the fan inlet and the panel partially obstructs the inlet collector, weakening the overall guiding effect of the inlet ring and increasing vortices in the impeller area. Especially at low flow rates, uneven impeller load and flow rate cause instability in the impeller flow to develop and increase at the boundary positions, resulting in more dead zones. In fans, there is a gap between the inner plane of the impeller and the volute. For ultra-thin fans, the narrow space forces some of the air already forced into the flow channel to flow back into the radially inner area of ​​the impeller blades (backflow). This backflow interferes with the airflow drawn in from the intake (mainstream), thus generating noise. Even if the inlet ring extends into the impeller, it cannot effectively prevent backflow. The characteristic curve of a range hood fan shows an overall downward trend; however, the line is not always downward in all areas, and in the low airflow region below 10 m³ / min, it is locally horizontal or upward. When operating under such conditions, the impeller is prone to stalling, the airflow inside the casing becomes unstable, and the noise level increases. This is a real-world scenario for users in high-rise residential buildings, resulting in low airflow and high noise levels when using the range hood.

[0005] In addition, such as Figure 1As shown, when the fan rotates at high speed, a localized negative pressure region A is generated in the radially inner portion of the air passage formed between the two blades of the impeller, facing the convex rear surface B. Due to the presence of negative pressure region A, the air in the airflow passage is forced to flow radially outward, and the air path narrows at region A. Therefore, not only does the air velocity increase significantly in this throat region, but vortices are also generated in negative pressure region A. This leads to operating losses for the fan, the airflow in the passage becomes separated from the convex rear surface B, and vortex noise is also increased. Summary of the Invention

[0006] The first technical problem to be solved by this utility model is to provide a fan that can eliminate local negative pressure areas in the air passage between blades, reduce eddies, and lower noise, in contrast to the above-mentioned prior art.

[0007] The second technical problem to be solved by this utility model is to provide a fan that can enhance airflow discharge pressure, increase exhaust volume, and reduce noise, in contrast to the above-mentioned prior art.

[0008] The third technical problem to be solved by this utility model is to provide a range hood that uses the aforementioned fan, in contrast to the prior art.

[0009] The technical solution adopted by this utility model to solve the first technical problem mentioned above is as follows: a fan, including a volute and an impeller disposed in the volute, the impeller including a plurality of radially arc-shaped blades arranged circumferentially, and an airflow channel is formed between adjacent blades, characterized in that: a slit extending axially is opened on the blade near the radially inner side.

[0010] Preferably, the slits include two slits that extend from the axial middle portion of the blade to the tip of the blade in opposite directions.

[0011] As an improvement, an arch bridge with an arc-shaped cross section is provided on the outer convex surface of the blade, and the arch bridge spans across a slit located near the air inlet side of the impeller.

[0012] Preferably, the distance between the arch bridge component and the air inlet front end of the blade is j, the length of the arch bridge component in the axial direction of the impeller is k, B / 9 < k < j, and B is the axial length of the impeller.

[0013] Preferably, the radial distance from the impeller center to the inner radial edge of the blade is R, and the radial distance from the impeller center to the slit is L, where L > 1.1R.

[0014] Preferably, along the airflow direction within the airflow channel, the angle between the radial tangent axis of the slit and the tangent on the concave surface of the blade at the slit position is X, where 90° < X < 180°.

[0015] Preferably, the slit gap width is w, dd / 30 < w < dd / 4, where dd is the width of the airflow channel between adjacent blades.

[0016] The technical solution adopted by this utility model to solve the second technical problem mentioned above is as follows: the thickness of the blade gradually decreases along the opposite direction of the air inlet axis and along the radial extension direction of the impeller.

[0017] Preferably, based on the change in blade thickness, a sharp edge is formed at the radially outer position of the front part of the blade.

[0018] The technical solution adopted by this utility model to solve the third technical problem mentioned above is: a range hood, characterized in that: it includes the aforementioned fan.

[0019] Compared with the prior art, the advantages of this invention are as follows: The fan in this invention has slits on its blades, and these slits are located upstream of the radial airflow during fan rotation. During impeller rotation, kinetic energy is applied to any air flowing along the outer convex surface of the blades. Utilizing this energy, the kinetic energy of the outward airflow along the outer convex surface of the blades increases. Through the slits, air is blown into the negative pressure region of the airflow channel to increase the kinetic energy of the airflow in that negative pressure region. Due to the centrifugal force of the impeller rotation, an airflow is generated in each airflow channel from the radially inner portion of the blades to the radially outer portion. The airflow is pressed against the concave surface of adjacent blades; therefore, a portion of the airflow is guided through the slits to the negative pressure region in the subsequent airflow channel, thus eliminating the negative pressure region in each airflow channel, improving the vortex problem caused by the negative pressure region in the airflow channel, and consequently reducing fan noise.

[0020] This fan is suitable for the working conditions of thin fans, which is beneficial for the design of thin fans.

[0021] The range hood using this fan operates stably, has low noise, and allows for the design of a smaller, thinner range hood. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the negative pressure region A between two blades in the prior art.

[0023] Figure 2 This is a perspective view of the fan in an embodiment of this utility model.

[0024] Figure 3 This is a perspective view of the impeller in an embodiment of the present invention.

[0025] Figure 4 for Figure 3 Another perspective view.

[0026] Figure 5This is a schematic diagram of the airflow channel between two blades in an embodiment of this utility model. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] like Figures 2 to 5 As shown, the fan in this embodiment includes a volute 1 and an impeller 2 disposed within the volute 1. The impeller 2 includes multiple radially curved blades 21 arranged circumferentially, with airflow channels 20 formed between adjacent blades 21. When the fan is working, the impeller 2 rotates, and external air enters the volute 1 axially through the air inlet on the front side of the volute 1. Under the centrifugal force generated by the rotation of the impeller 2, the air flows through the airflow channels 20 between the blades 21 and enters the internal space of the volute 1. Under the combined action of the volute 1 and the impeller 2 driving the airflow, the air is discharged through the air outlet opened on the volute 1.

[0029] As described in the background art, there is a local negative pressure area on the airflow channel 20 between the blades 21. In order to eliminate this negative pressure area, the structure of the blades 21 has been improved, thereby eliminating the negative pressure area on the airflow channel 20, eliminating the vortex in this negative pressure area, and reducing the operating noise.

[0030] Specifically, a slit 22 extending axially is provided on the blade 21 near the radially inner side. The slit 22 is located upstream of the radial flow of air when the fan rotates. Specifically, the radial distance R between the center of the impeller 2 and the radial inner edge of the blade 21 is the same as the radial distance L between the center of the impeller 2 and the slit 22, where L > 1.1R.

[0031] As the impeller 2 rotates, kinetic energy is applied to any air flowing along the outer convex surface of the blade 21. This energy increases the kinetic energy of the outward airflow along the outer convex surface of the blade 21. Through the slit 22, air is blown into the negative pressure region of the airflow channel 20 to increase the kinetic energy of the airflow in that region. Due to the centrifugal force of the rotating impeller 2, an airflow is generated in each airflow channel 20 from the radially inner portion of the blade 21 towards the radially outer portion. The airflow is pressed against the concave surface of adjacent blades 21; therefore, a portion of the airflow is guided through the slit 22 to the negative pressure region in the subsequent airflow channel 20, thus eliminating the negative pressure region in each airflow channel 20, improving the vortex problem caused by the negative pressure region in the airflow channel 20, and consequently reducing fan noise.

[0032] If the gap width of the slit 22 is too large, excessive air will be blown into the negative pressure area through the slit 22, which not only reduces the air driving efficiency of the fan but also causes noise generation. To ensure that the air passing through the slit 22 can exactly eliminate the negative pressure area in the air flow channel 20 without affecting the air driving efficiency of the fan and avoiding additional noise generation, it is necessary to limit the gap width of the slit 22 within a reasonable range. In this embodiment, the gap width of the slit 22 is w, where dd / 30 < w < dd / 4, and dd is the width of the air flow channel 20 between adjacent blades 21.

[0033] In addition, along the air flow direction in the air flow channel 20, the included angle between the radial section axis of the slit 22 and the tangent line on the concave surface of the blade 21 at the position of the slit 22 is X, where 90° < X < 180°. Selecting an appropriate angle for the included angle X can achieve the purpose of ensuring the elimination of the negative pressure area.

[0034] To eliminate the negative pressure area along the entire length of the blade 21 as much as possible, the slit 22 needs to cover the axial length of the blade 21 as much as possible along the axial length, but it is also necessary to ensure the structural strength of the blade 21. Based on this, there are two slits 22 in this embodiment, and the two slits 22 extend from the axial middle part of the blade 21 to the ends of the blade 21 in opposite directions. In this way, the middle area of the blade 21 remains intact in the width direction, effectively ensuring the structural stability and structural strength of the blade 21.

[0035] To further enhance the structural strength of the blade 21 without affecting the function of the slit 22, in this embodiment, an arch member 3 with an arc-shaped cross-section is provided on the convex surface of the blade 21. In this embodiment, the arch member 3 straddles the slit 22 located on the air inlet side of the impeller 2, and the arch member 3 is arranged as close as possible to the air inlet side position of the impeller 2, so that the separated air flow adheres to the blade 21 again, ensuring the continuity of the air flow on the air inlet side.

[0036] To ensure the continuity of the air flow on the air inlet side, in this embodiment, the distance between the arch member 3 and the air inlet front end of the blade 21 is j, and the length of the arch member 3 in the axial direction of the impeller 2 is k, where B / 9 < k < j, and B is the axial length of the impeller 2. k < j is to prevent the arch member from being too long and hindering the air flow movement, and B / 9 < k because there is a local negative pressure area in the air inlet area at the front end of the impeller 2, resulting in air flow convergence. Under the combined action of the arch member 3 and the slit 4, the negative pressure area in the air inlet area at the front end of the wheel can be eliminated.

[0037] Furthermore, the rear disc area of ​​impeller 2 is relatively enclosed due to the design of the drive structure. During operation, after the airflow enters impeller 2, it is radially discharged outward under the action of blades 21. Especially for thin-walled fans, the airflow path changes with a large curvature, making secondary vortices prone to occur at the rear disc area of ​​impeller 2. Based on the airflow direction, the airflow is relatively small at the front of the impeller 2 inlet and relatively large at the rear of the impeller 2 inlet.

[0038] In this embodiment, the thickness of the blade 21 gradually decreases along the opposite direction of the inlet air axis and along the radial outward extension direction of the impeller 2. Based on the thickness variation of the blade 21, a sharp edge 210 is formed at the radially outer position of the front part of the blade 21. Since the edge 210 is a very thin and sharp part, the resistance to the incoming airflow is very small, increasing static pressure while reducing noise, that is, increasing the airflow rate entering the impeller 2 with low noise. At the same time, the thickness variation of the blade 21 matches the distribution of the airflow rate in the impeller 2 along the inlet air axis, meeting the different airflow discharge requirements at different positions along the inlet air axis, minimizing the power consumption of the fan, reducing secondary eddies, and reducing operating noise.

[0039] This fan is better suited to the working conditions of thin fans, which is beneficial for the design of thin fans.

[0040] This utility model also relates to a range hood, including a housing and the aforementioned fan disposed within the housing. This range hood has low noise, a larger smoke extraction capacity per unit power consumption, and solves the problem of applying thin fans within it, making it highly advantageous for thin fan design.

[0041] In the specification and claims of this utility model, terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," are used to describe various exemplary structural parts and elements of the invention. However, the use of these terms is merely for illustrative purposes and is based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

Claims

1. A fan comprising a volute (1) and an impeller (2) disposed in the volute (1), the impeller (2) comprising a plurality of circumferentially disposed blades (21) having an arc-shaped radial cross section, a flow channel (20) being formed between adjacent blades (21), characterized in that: A slit (22) extending axially is provided on the blade (21) near the radially inner side.

2. The fan of claim 1, wherein: The slits (22) include two slits (22) that extend from the axial middle part of the blade (21) to the end of the blade (21) in opposite directions.

3. The fan of claim 2, wherein: An arch bridge component (3) with an arc-shaped cross section is provided on the outer convex surface of the blade (21), and the arch bridge component (3) spans across the slit (22) located near the air inlet side of the impeller (2).

4. The fan of claim 3, wherein: The distance between the arch bridge component (3) and the air inlet front end of the blade (21) is j, and the length of the arch bridge component (3) in the axial direction of the impeller (2) is k, B / 9 < k < j, where B is the axial length of the impeller (2).

5. The fan of any one of claims 1 to 4, wherein: The radial distance between the center of the impeller (2) and the inner radial edge of the blade (21) is R, and the radial distance between the center of the impeller (2) and the slit (22) is L, where L > 1.1R.

6. The fan of any one of claims 1 to 4, wherein: Along the airflow direction in the airflow channel (20), the angle between the radial tangent axis of the slit (22) and the tangent on the concave surface of the blade (21) at the slit (22) position is X, 90° < X < 180°.

7. The fan of any one of claims 1 to 4, wherein: The gap width of the slit (22) is w, dd / 30 < w < dd / 4, where dd is the width of the airflow channel (20) between adjacent blades (21).

8. The fan according to any one of claims 1 to 4, characterized in that: The thickness of the blade (21) gradually decreases in the opposite direction of the air intake axis and in the radial extension direction of the impeller (2).

9. The fan of claim 8, wherein: Based on the thickness variation of the blade (21), a sharp edge (210) is formed at the radially outer position of the front part of the blade (21).

10. A range hood characterized by: Includes the wind turbine as described in any one of claims 1 to 9.

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