A centrifugal fan and a range hood using the same

Abstract

The present invention discloses a centrifugal fan and a range hood incorporating the same. The centrifugal fan includes a volute, the volute comprising a front cover plate, a rear cover plate, and an annular wall. The annular wall is disposed between the front cover plate and the rear cover plate. A first transition structure is formed between the front cover plate and the annular wall, and a second transition structure is formed between the rear cover plate and the annular wall. The first and second transition structures are asymmetrically arranged. Compared to the prior art, the present invention has the advantage of designing the transition structure between the front and rear cover plates and the annular wall of the volute to be asymmetrical, thereby matching the flow state of the asymmetric flow within the centrifugal fan and effectively improving flow separation caused by asymmetric inlet air flow.

Description

Technical Field

[0001] The invention relates to a power device, in particular to a centrifugal fan and a range hood using the centrifugal fan. Background Art

[0002] Centrifugal fans offer high pressure and low noise, making them a common power source. They utilize a high-speed rotating impeller within a volute to perform both power generation and filtration. For example, they are commonly used in range hoods, where a centrifugal fan installed within the hood draws in and exhausts oil fumes. The centrifugal fan consists of a volute, an impeller mounted within the volute, and a motor that drives the impeller. As the impeller rotates, negative pressure is generated at the fan's center, drawing oil fumes from beneath the range hood into the fan. After being accelerated by the fan, the volute collects the fumes and guides them out of the room.

[0003] The structural design of a centrifugal fan is closely linked to the overall performance of the range hood. The volute, the primary airflow component in a centrifugal fan, consists primarily of a front cover, a rear cover, and a ring wall located between the two. The point where the front or rear cover meets the ring wall is typically a right-angle bend, which can easily create dead zones, leading to flow separation and energy loss.

[0004] In order to reduce the flow dead zone in the corner, some volute design improvements have adopted a gradual rounded corner transition. For example, Chinese patent application number 201020580680.6 discloses an air duct device for an air conditioner, which includes: a flat side wall plate and a volute structure air duct. The volute structure air duct includes a volute profile surface, the generatrix of the volute profile surface is perpendicular to the side wall plate, and a circular arc chamfer is provided between the volute profile surface and the side wall plate.

[0005] However, for this type of volute, the radius of the front and rear covers is usually consistent. Since centrifugal fans are affected by the motor side, the airflow conditions on both sides of the front and rear covers are different, and the space occupied by the corner flow separation area is not consistent. If the front and rear covers use the same radius design, it cannot meet the needs of asymmetric flow. In addition, the current radius design is usually an arc design, and the dimensions of the arc surface in the axial and radial directions are the same. It is not designed to match the depth and width of the volute, which may cause the problem of excessive radius occupying the flow channel space in one direction. On the other hand, larger gradual radius transition designs are commonly used on plastic volutes, and sheet metal processing requires stretching and forming, which places high demands on both materials and processing technology, and is costly. Therefore, further improvement is needed. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a centrifugal fan to address the deficiencies of the above-mentioned prior art, which can effectively improve the flow separation caused by asymmetric air inlet flow.

[0007] The second technical problem to be solved by the present invention is to provide a range hood using the above-mentioned centrifugal fan.

[0008] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a centrifugal fan, including a volute, the volute including a front cover plate, a rear cover plate and an annular wall, the annular wall is arranged between the front cover plate and the rear cover plate, a first transition structure is formed between the front cover plate and the annular wall, and a second transition structure is formed between the rear cover plate and the annular wall, characterized in that: the first transition structure and the second transition structure are arranged asymmetrically.

[0009] By designing the transition structure between the front and rear cover plates and the annular wall of the volute to be asymmetrical, the flow state of the asymmetric flow in the centrifugal fan is matched, thereby effectively improving the flow separation caused by the asymmetric air inlet flow.

[0010] Preferably, each transition structure appears as a line segment on a cross section and the line segment serves as a cross-sectional line segment of each transition structure, the cross-sectional line segment being one of an airfoil streamline, an ellipse, a Bezier curve, a spiral, a straight line, a broken line, and a polyline, and the cross section is the normal surface of the section at any position of the annular wall.

[0011] Furthermore, each transition structure appears as a line segment on a cross section and serves as a cross-sectional line segment of each transition structure, and the cross section is the normal surface of the section at any position of the annular wall; the sizes of the cross-sectional line segments of the first transition structure and the cross-sectional line segments of the second transition structure are different from each other, and the setting of the asymmetric structure is achieved through the design of different sizes.

[0012] Furthermore, the ratio of the air intake volume of the front and rear cover plates determines the size of the folding angle of the corresponding transition structure. The amount of air intake determines the airflow filling rate in the volute. The larger the air intake volume, the smaller the dead zone, and the folding angle cannot be too large. A first air inlet is provided on the front cover plate, and a motor bracket for mounting a motor is provided on the rear cover plate. The starting point of the cross-sectional line segment of the first transition structure is the first starting point, and the end point of the cross-sectional line segment of the first transition structure is the first end point. The starting point of the cross-sectional line segment of the second transition structure is the second starting point, and the end point of the cross-sectional line segment of the second transition structure is the second end point. The starting point of the cross-sectional line segment of each transition structure refers to the end point close to the annular wall, and the end point of the cross-sectional line segment of each transition structure refers to the end point close to the corresponding cover plate.

[0013] The distance from the first starting point to the adjacent axial end face of the volute is S1, and the distance from the second starting point to the adjacent axial end face of the volute is S3;

[0014] The ratio of the air inlet volume at the front cover and the rear cover of the volute is m, and satisfies Wherein k1 is a proportional coefficient, and the value range of k1 is 0 to 4.

[0015] Preferably, in order to better adapt to the proportional relationship between the front and rear air intakes, The value range is 0 to 2.

[0016] More preferably, since the difference between the front and rear air intake ratios is generally not too large, and the front cover is generally the main air intake side, a second air inlet is provided on the rear cover. The value range is 0.5~1.

[0017] Preferably, in order to avoid a large difference in the aspect ratio of the two transition structures, the shortest distance from the first end point to the line connecting the first starting point and the second starting point is S2, and the shortest distance from the second end point to the line connecting the first starting point and the second starting point is S4, and each distance value satisfies the following relationship: S4 / S2=k2*S3 / S1, where k2 is the proportional coefficient, and the value range of k2 is 0 to 4.

[0018] More preferably, a second air inlet is provided on the rear cover plate, and the value range of k2 is 1 to 2.

[0019] In order to adapt to the size of the volute, reduce the impact of an overly large transition structure on the mainstream area, prevent the transition structure from being too small, resulting in redundant flow dead zones that reduce efficiency, and adapt well to the flow states of different areas under asymmetric flow, the thickness of the volute is B, and satisfies S1 / B=0.01~0.1.

[0020] In order to adapt to the size of the volute, reduce the impact of an excessively large transition structure on the mainstream area, prevent the transition structure from being too small, resulting in redundant flow dead zones that reduce efficiency, and adapt well to the flow states of different areas under asymmetric flow, the width of the volute is L, and the shortest distance from the first end point to the line connecting the first starting point and the second starting point is S2, and S2 / L=0.005~0.05 is satisfied.

[0021] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a range hood, characterized in that: the centrifugal fan as described above is applied.

[0022] Furthermore, the centrifugal fan has an air outlet, which is formed by a front cover, a rear cover, and an annular wall. A hood is provided at the air outlet, and the hood includes a mounting base mounted thereon. The inner circumference of the mounting base of the hood matches the shape of the air outlet. The hood matches the curved / broken-line design of the volute, reducing flow losses during cross-sectional transitions and further leveraging the performance improvements provided by the volute design.

[0023] Compared with the prior art, the advantages of the present invention are: by making the transition structure between the front and rear cover plates and the annular wall of the volute an asymmetric setting, it matches the flow state of the asymmetric flow in the centrifugal fan, thereby effectively improving the flow separation caused by the asymmetric air inlet flow; according to the size of the volute body, the structural dimensions of the transition structure in two directions are constructed to ensure that the flow dead zone is reduced in all directions without affecting the mainstream flow area; the air outlet hood matches the curved / broken line design around the volute, reducing the flow loss during the cross-section transition process, and better exerting the performance improvement brought by this volute design. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 2 Schematic diagram of the three-dimensional structure of the volute of the first embodiment of the present invention;

[0026] Figure 3 A front view of a volute according to a first embodiment of the present invention;

[0027] Figure 4 A side view of a volute according to a first embodiment of the present invention;

[0028] Figure 5 A sectional view of a volute according to a first embodiment of the present invention;

[0029] Figure 6 for Figure 5 A schematic diagram of the partial I enlargement;

[0030] Figure 7 A side view of a volute according to a second embodiment of the present invention;

[0031] Figure 8 Schematic diagram of the three-dimensional structure of the air outlet cover of the range hood according to an embodiment of the present invention;

[0032] Figure 9 It is a bottom view of the air outlet cover of the range hood according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Since the embodiments disclosed in the present invention can be set in different directions, these terms indicating directions are only for illustration and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features.

[0035] See also Figure 1 and Figure 2 A range hood includes a centrifugal fan 100, a fan frame 200, and an air outlet cover 300. The centrifugal fan 100 is disposed within the fan frame 200, and the air outlet cover 300 is disposed at the air outlet of the centrifugal fan 100. The range hood shown in the figure is a top-suction range hood. Alternatively, the range hood may be of any existing type, such as a side-suction type, a low-draft type, or a split type.

[0036] The centrifugal fan 100 includes a volute 1 and an impeller 2 disposed in the volute 1 .

[0037] Example 1

[0038] See also Figures 2 to 6 The volute 1 includes a front cover 11, a rear cover 12, an annular wall 13 and an air outlet 17. The annular wall 13 is arranged between the front cover 11 and the rear cover 12. A motor bracket 14 is installed on the rear cover 12 for fixing the motor (the motor is used to drive the impeller 2, not shown). The above structure is the same as the existing volute structure. A first air inlet 111 is provided on the front cover 11, and a second air inlet 121 is provided on the rear cover 12. Among them, the first air inlet 111 is the main air inlet, and the second air inlet 121 is the auxiliary air inlet. The air flow rate on the main air inlet side is large, the air intake is smooth, and the vortex volume is relatively small. On the contrary, the vortex volume on the auxiliary air inlet side is relatively large due to the influence of the motor, the motor bracket 14, etc. Alternatively, the second air inlet 121 can also be omitted on the rear cover 12, but this position inside the volute 1 is still affected by the motor, the motor bracket 14, etc., and the same problem exists. The front cover plate 11, the rear cover plate 12 and the annular wall 13 form the air outlet 17. The air outlet 17 is provided with a volute 18 (flange) for connecting with the air outlet cover 300. The shape of the inner periphery of the volute 18 is adapted to the air outlet 17.

[0039] The thickness of the volute 1 is set to B, the width is set to L, and the height is set to H. The meanings of these parameters of the volute 1 are the same as those in the prior art.

[0040] The transition position between the front cover plate 11 and the annular wall 13 forms a first transition structure 15, and the transition position between the rear cover plate 12 and the annular wall 13 forms a second transition structure 16. Each transition structure appears as a curve (non-straight line) on a certain cross section, hereinafter referred to as a cross-sectional line segment. The line type of the cross-sectional line segment can be an airfoil streamline, an ellipse, a Bezier curve, a spiral, a straight line, a broken line, a polyline, etc. In this embodiment, it is a straight line. The above cross section refers to the normal surface of the section at any position of the annular wall 13. Figure 4 In the perspective shown in , the cross section may be a plane passing through the axis of the centrifugal fan 100 and perpendicular to the paper.

[0041] Due to the asymmetry of the flow of the range hood, the first transition structure 15 and the second transition structure 16 are asymmetrically arranged. In the present invention, the above-mentioned asymmetric arrangement mainly refers to different sizes. The size of each transition structure is closely related to the flow state of the centrifugal fan 100. Point M is the starting point (first starting point) of the cross-sectional line segment of the first transition structure 15, point N is the end point (first end point) of the cross-sectional line segment of the first transition structure 15, point M' is the starting point (second starting point) of the cross-sectional line segment of the second transition structure 16, and point N' is the end point (second end point) of the cross-sectional line segment of the second transition structure 16. Among them, the starting point of the cross-sectional line segment of each transition structure refers to the end point close to the annular wall 13, and the end point of the cross-sectional line segment of each transition structure refers to the end point close to the corresponding cover plate. The sizes of line segment MN and line segment MN' are different from each other (the shapes are the same).

[0042] The distance from the first starting point M to the adjacent axial end face of the volute 1 (which can be the outer surface of the front cover plate 11 facing the outside of the volute 1) is S1, the shortest distance from the first end point N to the line connecting the first starting point M and the second starting point M' is S2, the distance from the second starting point M' to the adjacent axial end face of the volute 1 (which can be the outer surface of the rear cover plate 12 facing the outside of the volute 1) is S3, and the shortest distance from the second end point N' to the line connecting the first starting point M and the second starting point M' is S4.

[0043] The ratio of the air volume entering the volute 1 through the front cover 11 (first air inlet 111) to the air volume entering through the rear cover 12 (second air inlet 121) is m, a value typically obtained through range hood flow field simulation. Based on these known values, the specific parameters of the start and end points of each transition structure are obtained using the following relationship. The start and end points are then connected using airfoil streamlines, ellipses, Bezier curves, spirals, straight lines, broken lines, or polylines.

[0044] The ratio of the air intake volume of each air inlet determines the size of the folding angle of the corresponding transition structure. The amount of air intake determines the airflow filling rate in the volute 1. The larger the air intake volume, the smaller the dead zone and the folding angle cannot be too large. K1 represents the proportional coefficient, and the value range of K1 is 0 to 4. The value range should be 0 to 2. 0 is generally applicable to the centrifugal fan 100 with single air inlet, and the first transition structure 15 can be omitted (the second transition structure 16 is retained). Considering the centrifugal fan 100 with double air inlet, the difference between the front and rear air inlet ratios is generally not too large, and the front cover 11 is generally the main air inlet side, so More preferably, it is 0.5 to 1.

[0045] Each transition structure is composed of two directions, and the distances of the transition structures in the two directions may be inconsistent, that is, S1 and S2 may be inconsistent, and S3 and S4 may be inconsistent, but they are also related to the proportion of the air intake volume. Therefore, the two also have the following relationship: S4 / S2=k2*S3 / S1, where k2 represents the proportional coefficient. The value range of k2 is preferably 0 to 4, and more preferably 1 to 2, to avoid a large difference in the aspect ratio of the two transition structures.

[0046] The specific value of S1 is related to the thickness B of the volute 1, and S2 is related to the width L or height H. If S1 and S2 are too large, it will affect the mainstream area (the mainstream area is the flow away from the wall areas of the volute 1, and the flow is no longer affected by the wall surface). If they are too small, the optimization is limited. Therefore, the preferred value range of S1 and S2 is S1 / B = 0.01~0.1; S2 / L = 0.005~0.05.

[0047] The above settings enable the sizes of the transition structures on both sides to adapt to the proportional relationship between the air inlet volumes of the main and auxiliary air inlets, and also to adapt to the size of the volute, reducing the impact of an excessively large transition structure on the mainstream area, and preventing the transition structure from being too small, resulting in redundant flow dead zones that reduce efficiency, and are well adapted to the flow states of different areas under asymmetric flow.

[0048] After the cross-sectional line segments are determined, the curve is preferably kept consistent on the circumferential profile of the annular wall 13 (if inconsistent, it is necessary to determine the cross-sectional line segments at different azimuth angles on a circle and mix them). The outer sides of the front cover plate 11 and the rear cover plate 12 of the volute 1 can be processed by simple molding or the annular wall 13 through a rolling process. When the various components of the above-mentioned volute 1 are assembled, the overlapping parts of the annular wall 13 and the cover plates can be welded. This method is low-cost and easy to process. A flattened straight section can be set adjacent to each transition structure to overlap with the corresponding annular wall 13 or each cover plate to achieve surface contact and then welded.

[0049] Example 2

[0050] See also Figure 7In this embodiment, the cross-sectional line segments of the first transition structure 15 and the second transition structure 16 are arc-shaped.

[0051] See also Figure 8 and Figure 9 For the entire range hood, the air outlet 17 of the centrifugal fan 100 of the range hood generally needs to be connected to the smoke exhaust pipe, so an air outlet hood 300 is added between the two to achieve the conversion from a square to a round cross-section. In order to better play the effect of the transition structure design of the above-mentioned volute 1, a matching design is required for the air outlet hood 300. Along the direction of oil smoke outflow, the air outlet hood 300 includes a mounting base 301, a transition section 302 and a smoke pipe connecting section 303 in sequence, wherein the transition section 302 is formed by a mixed transition of the linear shape of the air outlet 17 of the volute 1 and the linear shape of the inner circle of the volute casing 18. In order to make the transition smoother and the resistance smaller, the inner peripheral shape of the transition section 302 of the air outlet hood 300 is consistent with the shape of the air outlet 17.

Claims

1. A centrifugal fan, comprising a volute (1), the volute (1) comprising a front cover (11), a rear cover (12) and an annular wall (13), the annular wall (13) being arranged between the front cover (11) and the rear cover (12), a first transition structure (15) being formed between the front cover (11) and the annular wall (13), and a second transition structure (16) being formed between the rear cover (12) and the annular wall (13), characterized in that: The first transition structure (15) and the second transition structure (16) are arranged asymmetrically; Each transition structure is presented as a line segment on a cross section and serves as a cross section line segment of each transition structure, wherein the cross section is a normal surface of a section at any position of the annular wall (13); the cross section line segment of the first transition structure (15) and the cross section line segment of the second transition structure (16) are different in size from each other; The front cover (11) is provided with a first air inlet (111), the rear cover (12) is provided with a motor bracket (14) for mounting a motor, the starting point of the cross-sectional line segment of the first transition structure (15) is a first starting point (M), the end point of the cross-sectional line segment of the first transition structure (15) is a first end point (N), the starting point of the cross-sectional line segment of the second transition structure (16) is a second starting point (M'), the end point of the cross-sectional line segment of the second transition structure (16) is a second end point (N'), the starting point of the cross-sectional line segment of each transition structure is an end point close to the annular wall (13), and the end point of the cross-sectional line segment of each transition structure is an end point close to the corresponding cover; The distance from the first starting point (M) to the axial end face of the adjacent volute (1) is S1, and the distance from the second starting point (M') to the axial end face of the adjacent volute (1) is S3; The ratio of the air intake volume at the front cover plate (11) and the rear cover plate (12) of the volute (1) is m, and satisfies Wherein k1 is a proportional coefficient, and the value range of k1 is 0 to 4.

2. The centrifugal fan according to claim 1, characterized in that: The value range is 0 to 2.

3. The centrifugal fan according to claim 2, characterized in that: The rear cover (12) is provided with a second air inlet (121). The value range is 0.5~1.

4. The centrifugal fan according to claim 1, characterized in that: The shortest distance from the first end point (N) to the line connecting the first starting point (M) and the second starting point (M') is S2, and the shortest distance from the second end point (N') to the line connecting the first starting point (M) and the second starting point (M') is S4. The distance values satisfy the following relationship: S4 / S2=k2*S3 / S1, where k2 is the proportional coefficient, and the value range of k2 is 0 to 4.

5. The centrifugal fan according to claim 4, characterized in that: The rear cover plate (12) is provided with a second air inlet (121), and the value range of k2 is 1 to 2.

6. The centrifugal fan according to claim 1, characterized in that: The thickness of the volute (1) is B, and satisfies S1 / B=0.01-0.

1.

7. The centrifugal fan according to claim 1, characterized in that: The width of the volute (1) is L, the shortest distance from the first end point (N) to the line connecting the first starting point (M) and the second starting point (M') is S2, and S2 / L=0.005-0.05 is satisfied.

8. A range hood, characterized in that: The centrifugal fan according to any one of claims 1 to 7 is used.

9. The range hood according to claim 8, characterized in that: The centrifugal fan has an air outlet (17), and the air outlet (17) is surrounded by a front cover (11), a rear cover (12) and a ring wall (13). An air outlet cover (300) is provided at the air outlet (17), and the air outlet cover (300) includes a mounting base (301) mounted at the air outlet (17). The inner peripheral shape of the mounting base (301) of the air outlet cover (300) is consistent with the shape of the air outlet (17).

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