A centrifugal fan and a range hood using the same

Abstract

The application discloses a centrifugal fan and a range hood applying the same. The centrifugal fan comprises an impeller, the impeller comprises a disc far from an air inlet side and blades; the centrifugal fan further comprises annular guide vanes, the guide vanes are arranged around the outlets of the blades and extend along the radial direction of the centrifugal fan away from the fixing position of the blades; along the axial direction of the centrifugal fan, the guide vanes have at least two arranged along the axial direction on the same side of the disc far from the air inlet side, and the height of the guide vanes gradually increases with the increase of the distance from the disc far from the air inlet side. Compared with the prior art, the centrifugal fan has the advantages that a series of guide vanes with different height sizes are arranged at the outlets of the blades, the height of the guide vanes is unevenly matched with the axial airflow, the airflow is induced to flow to the outlets, the transverse flow is reduced, the risk of developing into secondary flow or even backflow is reduced, the overall performance of the impeller is improved, the air volume and the efficiency can be improved under the condition that the size or the rotating speed is unchanged, and the noise is reduced.

Description

Technical Field

[0001] This invention relates to power devices, particularly a centrifugal fan, and a range hood using the centrifugal fan. Background Technology

[0002] Multi-blade centrifugal fans are characterized by high pressure and low noise, making them a common power source for many systems. They utilize a high-speed rotating impeller within a volute to perform both work and filtration. For example, they are frequently used in range hoods. A multi-blade centrifugal fan installed inside the hood draws in and exhausts cooking fumes. The fan consists of a volute, an impeller housed within the volute, and a motor that drives the impeller. As the impeller rotates, a negative pressure suction is generated at the center of the fan, drawing the cooking fumes from below into the fan. After being accelerated by the fan, the volute collects the fumes and guides them outdoors.

[0003] Traditionally, multi-blade centrifugal fans primarily operate in the central area (or, for single-suction models with short axial dimensions, near the rear plate) of range hoods. (See [reference needed]). Figure 6 and Figure 7 ,in Figure 6 The middle arrow indicates the gas flow path. As shown in the figure, due to the uneven intake along the axis, there is a pressure difference along the axis after the airflow flows out of the impeller channel. This pressure difference can easily cause the airflow to form a large secondary flow vortex 100 in the volute, and even develop to flow back to the inlet area from the front and rear disc areas, which reduces the overall aerodynamic efficiency, increases noise, and results in a low proportion of effective working blade segments. The truly effective working blade segments only account for a small section near the middle disc.

[0004] Common solutions to increase airflow often rely on increasing the rotation speed or size. Increasing the rotation speed leads to further noise, while increasing the size further encroaches on cabinet space. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a centrifugal fan that reduces secondary flow vortices at the impeller outlet, improves the overall work capacity of the impeller, and reduces noise.

[0006] The second technical problem to be solved by the present invention is to provide a range hood that uses the above-mentioned centrifugal fan.

[0007] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: a centrifugal fan, comprising an impeller, the impeller including a disc away from the air inlet side and at least two blades, the blades being fixed to the disc away from the air inlet side; characterized in that:

[0008] The centrifugal fan also includes annular guide vanes that surround the outlet of each blade and extend radially outward from the fixing point with the blade.

[0009] Along the axial direction of the centrifugal fan, on the same side of the disk away from the air inlet side, the guide vanes have at least two arranged at axial intervals, and the height of the guide vanes gradually increases as the distance from the disk away from the air inlet side increases.

[0010] By setting a series of guide vanes of different heights at the blade outlet, the height of the guide vanes is matched with the uneven axial airflow, inducing the airflow to flow towards the outlet, reducing lateral flow, reducing the risk of developing into secondary flow or even backflow, and improving the overall work capacity of the impeller. It can increase air volume and efficiency and reduce noise without changing the size or speed.

[0011] Preferably, along the axial direction of the centrifugal fan, on the same side of the disc furthest from the air inlet side, the height difference between any two adjacent guide vanes is ΔH, where ΔH is determined by... It is determined that β ranges from [0.2°, 25°], and L is the distance between the two adjacent guide vanes.

[0012] Preferably, the height of the guide vane is H, the outer diameter of the impeller is D2, and the value range of H:D2 is [0.02, 0.08]. If H is too small, the guide vane will be difficult to install; if it is too large, the frictional resistance will be too high, and it will easily interfere with the volute tongue on the volute.

[0013] To further adapt to the uneven airflow along the axis, guide the airflow toward the outlet and reduce secondary flow, along the axis of the centrifugal fan, on the same side of the disk away from the air inlet side, the guide vanes have at least three arranged at intervals along the axis, and the spacing between two adjacent guide vanes gradually decreases as the distance from the disk away from the air inlet side increases.

[0014] Preferably, along the axial direction of the centrifugal fan, on the same side of the disc furthest from the air inlet side, in any three sequentially arranged guide vanes, the spacing between two adjacent guide vanes is L1 and L2, respectively, and the value range of L2 / L1 is [0.6, 1).

[0015] Furthermore, the guide vane is provided with through holes that extend through both sides of the guide vane along its axial direction. The through holes can generate vortices, enhancing the guiding effect on areas far from the main flow. By utilizing the vortices generated by the through holes and the energy of the boundary layer near the guide vane, the airflow can better maintain its original direction after exiting the guide vane, further reducing subsequent deflection and frictional losses between the airflow and the guide vane.

[0016] Preferably, the distance between the center of the through hole and the outer edge of the guide plate is h, the height of the guide plate is H, and the value of h / H is in the range of [0.1, 0.6].

[0017] Preferably, the outer diameter of the impeller is D2. Along the axial direction of the centrifugal fan, on the same side of the disc furthest from the air inlet side, the ratio of the spacing between any two adjacent guide vanes to D2 ranges from [0.015, 0.15]. If this ratio is too low, the vanes will be too dense, resulting in excessive frictional resistance and increased weight, thus reducing impeller efficiency; if it is too high, the vanes will be too sparse, weakening or diminishing the guiding effect.

[0018] Preferably, the centrifugal fan further includes a volute, on which an air inlet is formed, and the impeller is a single-suction impeller or a double-suction impeller;

[0019] When the impeller is a single-suction impeller, the number of air inlets is one. The impeller includes a front plate and a rear plate. The blades are fixed to the front plate and the rear plate respectively. The front plate is close to the air inlet, and the plate away from the air inlet side is the rear plate.

[0020] When the impeller is a double-suction impeller, there are two air inlets. The impeller includes a front plate, a middle plate, and a rear plate. The blades are fixed to the front plate, the middle plate, and the rear plate respectively. The front plate and the rear plate are close to one of the air inlets. The plate away from the air inlet side is the middle plate.

[0021] Preferably, the guide vane is mainly used for airflow outside the main working area. The guide vane is arranged outside the mainstream area at the outlet of the blade. The mainstream area is located adjacent to the disk away from the air inlet side. Along the axial direction of the centrifugal fan, the ratio of the axial height of the mainstream area to the axial height of the impeller ranges from [0.1, 0.5].

[0022] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a range hood, characterized in that: it uses a centrifugal fan as described above.

[0023] Compared with the prior art, the advantages of this invention are as follows: By setting a series of guide vanes of different heights at the blade outlet, the height of the guide vanes is matched with the uneven axial airflow, inducing the airflow to flow towards the outlet, reducing lateral flow, reducing the risk of developing into secondary flow or even backflow, and improving the overall work capacity of the impeller. It can increase air volume and efficiency and reduce noise without changing the size or speed. By setting the variable spacing of the guide vanes, it can further adapt to the uneven axial airflow to guide the airflow towards the outlet and reduce secondary flow. The through holes on the guide vanes enhance the guiding effect on the area far from the mainstream, and the vortex generated by the through holes and the energy of the boundary layer near the guide vanes make the airflow maintain its original direction better after flowing out of the guide vanes, further reducing subsequent deflection and friction loss between the airflow and the guide vanes. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a centrifugal fan according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 A magnified schematic diagram of part I;

[0026] Figure 3 for Figure 1 A magnified schematic diagram of part II;

[0027] Figure 4 This is a schematic diagram of a centrifugal fan with a concealed volute and motor (double-suction impeller) according to an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of a centrifugal fan with a concealed volute and motor (single-suction impeller) according to an embodiment of the present invention.

[0029] Figure 6 A cross-sectional view of a centrifugal fan in the prior art;

[0030] Figure 7 This is a schematic diagram of the flow field simulation for a centrifugal fan using existing technology. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention 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. Since the embodiments disclosed in this invention can be arranged in different directions, these terms indicating direction are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0033] See Figures 1-4 A centrifugal fan includes a volute 1, an impeller 2 disposed within the volute 1, and a motor 3 for driving the impeller 2 to rotate. The volute 1 includes two spaced-apart cover plates 11 and an annular wall 12 formed between the cover plates 11, with an air inlet 13 provided on the cover plates 11.

[0034] Impeller 2 includes a front disc 21, a rear disc 22, a middle disc 23 positioned between the front disc 21 and the rear disc 22, and blades 24. Both cover plates 11 have air inlets 13, with the front disc 21 and the rear disc 22 close to their respective air inlets 13. Blades 24 extend axially along the centrifugal fan, passing through the front disc 21, middle disc 23, and rear disc 22, and are fixed to each of them. The number of blades 24 is not less than two, preferably around 60, forming a double-suction impeller, and the centrifugal fan is a double-inlet fan. Impeller 2 can also be replaced by one that does not include the middle disc 23, forming a single-suction impeller; see [reference needed]. Figure 5 At this point, only one cover plate 11 has an air inlet 13, with the front plate 21 close to the air inlet 13 and the rear plate 22 away from the air inlet 13. The above structure is the same as that of existing centrifugal fans, and will not be described in detail here.

[0035] The centrifugal fan also includes guide vanes 4, which are annular and arranged around the outlet of each blade 24 (the outlet being the outer edge of the blade 24). There may be one or at least two guide vanes 4; when there are at least two, the guide vanes 4 are spaced apart along the axial direction of the centrifugal fan. Since the axial airflow in the main flow region is not significantly uneven, the guide vanes 4 are preferably located outside the main flow region at the outlet of the blade 24 of the impeller 2, which also reduces costs. Here, the "main flow region" refers to the main working area, defined as follows: the main flow region is located adjacent to the disc away from the air inlet side, along the axial direction of the centrifugal fan, and the ratio of the axial height of the main flow region to the axial height of the impeller 2 is [0.1, 0.5]. When impeller 2 is a single-suction impeller, the disc furthest from the inlet side is the rear disc 22. In this case, the mainstream area is located between the rear disc 22 and the front disc 21, extending from the rear disc 22 to the front disc 21. The guide vane 4 is positioned between the front disc 21 and the rear disc 22. When impeller 2 is a double-suction impeller, the disc furthest from the inlet side is the middle disc 23. In this case, the mainstream area is located on both axial sides of the middle disc 23, maintaining the overall axial height as described above, without strictly limiting the ratio between the two sides of the middle disc 23. The guide vane 4 is positioned between the front disc 21 and the middle disc 23, and between the rear disc 22 and the middle disc 23. Of course, guide vanes 4 can also be positioned within the mainstream area.

[0036] The following explanation uses a dual-inlet fan as an example; the single-inlet fan is similar, except that the middle disc 23 is replaced by the rear disc 22. For ease of processing and installation, the guide vanes 4 and blades 24 can be fixed together by snap-fitting, welding, or bonding, extending radially outward from their fixing point to the blades 24. Along the axial direction of the centrifugal fan, on the same side of the middle disc 23 (i.e., between the front disc 21 and the middle disc 23, or between the middle disc 23 and the rear disc 22; the same side has the same meaning below), the spacing between adjacent guide vanes 4 gradually decreases as they move further away from the main flow area, meaning the guide vanes 4 become increasingly dense, increasing the airflow guiding effect. Preferably, on the same side of the central plate 23, three guide vanes 4 are arranged in sequence, with the spacing between two adjacent guide vanes 4 being L1 and L2, respectively. L1 is the spacing between the guide vane 4 closest to the central plate 23 and the middle guide vane 4, and L2 is the spacing between the middle guide vane 4 and the guide vane 4 furthest from the central plate 23. The axial variation law is: the value range of L2 / L1 is [0.6, 1).

[0037] Let the outer diameter of impeller 2 be D2. On the same side of the middle disk 23, the ratio of the distance between two adjacent guide vanes 4 to D2 can be selected from [0.015, 0.15]. If it is too low, it will be too dense, the frictional resistance of the guide vanes 4 will be too large, the weight will increase, and the efficiency of impeller 2 will be reduced; if it is too high, it will be too sparse, and the guiding effect will be weakened or not obvious.

[0038] The height of the guide vane 4 is H, and the value of H:D2 ranges from [0.02, 0.08]. If H is too small, the guide vane 4 will be difficult to install; if it is too large, the frictional resistance will be too high, and it will easily interfere with the volute tongue on the volute 1. Here, the height is defined as the height of the cross-section of the guide vane 4 in the radial direction of the centrifugal fan. This cross-section is a section passing through the axis of the centrifugal fan and perpendicular to the radial plane of the centrifugal fan. Figure 1 The image shows the plane containing the paper. From... Figure 2 As can be seen from point 3, the guide vane 4 is a sheet of uniform thickness with a roughly rectangular cross-section. On the same side of the center plate 23, the height difference between any two adjacent guide vanes 4 is ΔH, where the height of the guide vane 4 closer to the center plate 23 is less than the height of the guide vane 4 farther from the center plate 23. According to... ΔH is obtained, where β ranges from [0.2°, 25°], and L is the distance between any two adjacent guide vanes 4.

[0039] The guide vane 4 has through holes 41, which are preferably cylindrical and have a diameter ranging from [1 to 10] mm. The through holes 41 are preferably in at least two sets and are arranged at intervals along the height direction of the guide vane 4. The ratio of the distance h between the center of the through hole 41 and the outer edge of the guide vane 4 (the side away from the blade 24) to the height H of the guide vane 4 is in the range of [0.1 to 0.6].

[0040] See also Figure 3 The arrows indicate the gas flow path. The airflow from the blade 24 is deflected and adjusted after passing through the guide vane 4. The through holes 41 on the guide vane 4 can generate vortices, enhancing the guiding effect on the region far away from the mainstream (radially far away). The vortices generated by the through holes 41 (circled in the figure) and the energy of the boundary layer near the guide vane 4 are used to help the airflow maintain its original direction after exiting the guide vane 4, further reducing subsequent deflection and friction loss between the airflow and the guide vane 4.

Claims

1. A centrifugal fan, comprising an impeller (2), said impeller (2) including a disk away from the air inlet side and at least two blades (24), said blades (24) being fixed to the disk away from the air inlet side; characterized in that: The centrifugal fan also includes an annular guide vane (4), which surrounds the outlet of each blade (24) and extends radially outward from the fixing point with the blade (24). Along the axial direction of the centrifugal fan, on the same side of the disk away from the air inlet side, the guide vanes (4) have at least three arranged at intervals along the axial direction. As the distance from the disk away from the air inlet side increases, the height of the guide vanes (4) gradually increases, and the spacing between two adjacent guide vanes (4) gradually decreases.

2. The centrifugal fan according to claim 1, characterized in that: Along the axial direction of the centrifugal fan, on the same side of the disc furthest from the air inlet side, the height difference between any two adjacent guide vanes (4) is ΔH, where ΔH is determined by... The value of β is determined to be in the range of [0.2°, 25°], and L is the distance between the two adjacent guide vanes (4).

3. The centrifugal fan according to claim 1 or 2, characterized in that: The height of the guide vane (4) is H, the outer diameter of the impeller (2) is D2, and the range of H:D2 is [0.02, 0.08].

4. The centrifugal fan according to claim 1, characterized in that: Along the axial direction of the centrifugal fan, on the same side of the disc furthest from the air inlet side, among any three sequentially arranged guide vanes (4), the spacing between two adjacent guide vanes (4) is L1 and L2, respectively, and the value range of L2 / L1 is [0.6, 1).

5. The centrifugal fan according to claim 1 or 2, characterized in that: The guide plate (4) has a through hole (41) that penetrates both sides of the guide plate (4) along its axial direction.

6. The centrifugal fan according to claim 5, characterized in that: The distance between the center of the through hole (41) and the outer edge of the guide plate (4) is h, the height of the guide plate (4) is H, and the value range of h / H is [0.1, 0.6].

7. The centrifugal fan according to claim 1 or 2, characterized in that: The outer diameter of the impeller (2) is D2. Along the axial direction of the centrifugal fan, on the same side of the disc away from the air inlet side, the ratio of the distance between any two adjacent guide vanes (4) to D2 ranges from [0.015, 0.15].

8. The centrifugal fan according to claim 1 or 2, characterized in that: The centrifugal fan also includes a volute (1), on which an air inlet (13) is formed, and the impeller (2) is a single-suction impeller or a double-suction impeller; When the impeller (2) is a single-suction impeller, the number of air inlets (13) is one. The impeller (2) includes a front plate (21) and a rear plate (22). The blades (24) are fixed to the front plate (21) and the rear plate (22) respectively. The front plate (21) is close to the air inlet (13), and the plate away from the air inlet side is the rear plate (22). When the impeller (2) is a double-suction impeller, there are two air inlets (13). The impeller (2) includes a front plate (21), a middle plate (23) and a rear plate (22). The blades (24) are fixed to the front plate (21), the middle plate (23) and the rear plate (22) respectively. The front plate (21) and the rear plate (22) are close to one of the air inlets (13) respectively. The plate away from the air inlet side is the middle plate (23).

9. The centrifugal fan according to claim 8, characterized in that: The guide vane (4) is arranged outside the mainstream area at the outlet of the blade (24). The mainstream area is located adjacent to the disk away from the air inlet side. Along the axial direction of the centrifugal fan, the ratio of the axial height of the mainstream area to the axial height of the impeller (2) ranges from [0.1, 0.5].

10. A range hood, characterized in that: The application uses a centrifugal fan as described in any one of claims 1 to 9.

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