Centrifugal fan and range hood applying same

Abstract

The utility model discloses a centrifugal fan and a range hood applying the centrifugal fan, the centrifugal fan comprises a volute, the volute comprises a first cover plate, a second cover plate, an annular wall and a volute tongue, the annular wall and the volute tongue are arranged between the first cover plate and the second cover plate, and an air outlet is defined by the first cover plate, the second cover plate and the annular wall; the impeller is arranged in the volute; the centrifugal fan further comprises a gap adjusting unit which is at least adjacent to the air inlet of the centrifugal fan, the gap adjusting unit extends from the end, away from the air outlet, of the volute tongue to the direction away from the volute tongue, and the gap adjusting unit is arranged on the side, facing the interior of the volute, of the first cover plate and / or the second cover plate. The gap adjusting unit is tightly attached to the annular wall.

Description

Technical Field

[0001] This utility model relates to a hydraulic power device, and more particularly to 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] The volute tongue is used to prevent a small amount of gas from circulating within the fan casing. Typically, once a fan is designed and manufactured, its shape is fixed, and the radius of the volute tongue cannot be adjusted. To optimize fan performance, structural improvements are usually made to the volute tongue shape, such as using an inclined volute tongue, a stepped volute tongue, or a biomimetic volute tongue, as disclosed in Chinese patent applications 202322263511.X, 202110483722.7, and 201710899188.1.

[0004] The volute tongue and the area downstream of the volute tongue are the areas where the flow separation is most obvious. In this area, part of the airflow flows out from the air outlet, while the other part flows back to the volute shell. The existing technology mentioned above can only adjust the gap at the volute tongue, but cannot improve the situation where there is a lot of backflow and low work capacity in the local area downstream of the volute tongue. Utility Model Content

[0005] The first technical problem to be solved by this utility model is to address the shortcomings of the existing technology by providing a centrifugal fan that can improve local backflow downstream of the volute tongue and enhance the fan's work capacity.

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

[0007] The technical solution adopted by this utility model to solve the first technical problem mentioned above is: a centrifugal fan, comprising:

[0008] The volute includes a first cover plate, a second cover plate, an annular wall disposed between the first and second cover plates, and a volute tongue, wherein the first cover plate, the second cover plate, and the annular wall form an air outlet; and

[0009] The impeller is housed inside the volute.

[0010] Its features are:

[0011] The centrifugal fan also includes a gap adjustment unit that is at least adjacent to the air inlet of the centrifugal fan. The gap adjustment unit extends from the end of the volute tongue away from the air outlet in a direction away from the volute tongue. The gap adjustment unit is located on the side of the first cover plate and / or the second cover plate facing the inside of the volute. The gap adjustment unit is in close contact with the annular wall.

[0012] By setting up a gap adjustment unit, a low-speed zone can be formed in the cavity between the impeller and the air inlet (collector), effectively reducing gas backflow at the gap between the air inlet (collector) and the impeller, improving the mixing of the intake air and the backflowing gas in the gap, reducing the axial velocity of the intake air in the front and rear plates of the impeller, and improving the work capacity of the front and rear plates of the impeller; at the same time, adjusting the gap between the volute profile and the impeller outlet solves the airflow backflow in the volute tongue area (the internal area of ​​the volute) caused by this gap. The arrangement and installation are highly feasible and can be used as part of the downstream characteristics of the volute tongue.

[0013] Preferably, the gap adjustment unit is a component with equal thickness in the radial direction of the impeller.

[0014] Preferably, to ensure a safe clearance between the clearance adjustment unit and the impeller, the clearance between the volute tongue and the outer periphery of the impeller is t, and the ratio of the thickness of the clearance adjustment unit in the radial direction of the impeller to t is 0.3 to 0.5.

[0015] Preferably, the thickness of the gap adjustment unit in the radial direction of the impeller is ≤8mm.

[0016] Preferably, the base circle of the volute profile has a base circle center, and the angle between the two ends of the gap adjustment unit profile and the line connecting the base circle center is α, and the value of α ranges from 0 to 90°. This is the area with the most backflow downstream of the volute tongue, which is improved by setting a gap adjustment unit.

[0017] Furthermore, the centrifugal fan is a dual-inlet fan. The air inlet of the centrifugal fan includes a first air inlet formed on the first cover plate and a second air inlet formed on the second cover plate. There are two gap adjustment units, referred to as the first gap adjustment member and the second gap adjustment member, respectively. The first gap adjustment member is disposed on the side of the first cover plate facing the inside of the volute, and the second gap adjustment member is disposed on the side of the second cover plate facing the inside of the volute.

[0018] Furthermore, the thickness of the first gap adjusting member in the radial direction of the impeller is d1, and the thickness of the second gap adjusting member in the radial direction of the impeller is d2. The first air inlet is the main air inlet, and the second air inlet is the auxiliary air inlet. d1 and d2 also satisfy the following relationship: d2 > d1. Since the air volume at the second air inlet is small, the gap between the gap adjusting unit and the impeller can be set to be smaller to obtain a better backflow improvement effect.

[0019] By appropriately setting the axial thickness of the gap adjustment unit, the radial clearance between the volute profile and the impeller can be adjusted, reducing impeller outlet backflow. Simultaneously, a suitable axial thickness can be set according to the different flow rates at each air inlet. The axial thickness of the first gap adjustment component along the impeller axis is δ. f The axial thickness of the second gap adjusting member along the axis of the impeller is δ. b The total axial thickness of the two gap adjusting components is δ = δ f +δ b ;

[0020] The impeller includes a front plate and a rear plate. The front plate is close to the first cover plate of the volute, and the rear plate is close to the second cover plate of the volute. The axial distance between the front plate of the impeller and the first cover plate of the volute is δ1, and the axial distance between the rear plate of the impeller and the second cover plate of the volute is δ2. The total axial clearance between the impeller and the volute is δ0 = δ1 + δ2.

[0021] And it satisfies the following relationship: δ / δ0=δ f / δ1=δ b / δ2=a, where the value of a ranges from 0 to 7.5.

[0022] By reasonably setting the axial thickness of the gap adjustment unit, the radial clearance between the volute profile and the impeller is adjusted, thereby reducing impeller outlet backflow. The total axial thickness of the gap adjustment unit is δ.

[0023] The impeller includes a front plate and a rear plate. The front plate is close to the first cover plate of the volute, and the rear plate is close to the second cover plate of the volute. The axial distance between the front plate of the impeller and the first cover plate of the volute is δ1, and the axial distance between the rear plate of the impeller and the second cover plate of the volute is δ2. The total axial clearance between the impeller and the volute is δ0 = δ1 + δ2.

[0024] And it satisfies the following relationship: the value range of δ / δ0 is 0 to 7.5.

[0025] The technical solution adopted by this utility model to solve the second technical problem mentioned above is: a range hood, characterized in that: it uses a centrifugal fan as described above.

[0026] Compared with the prior art, the advantages of this utility model are as follows: by setting a gap adjustment unit, a low-speed zone can be formed in the cavity between the impeller and the air inlet (collector), which effectively reduces the gas backflow at the gap between the air inlet (collector) and the impeller, and improves the mixing of the intake air and the backflow gas in the gap, reduces the axial velocity of the intake air in the front and rear discs of the impeller, and improves the work capacity of the front and rear discs of the impeller; at the same time, by adjusting the gap between the volute profile and the impeller outlet, the airflow backflow in the volute tongue area (the internal area of ​​the volute) caused by this gap is solved, and the arrangement and installation are highly feasible, and it can be used as part of the downstream features of the volute tongue. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a range hood according to an embodiment of the present utility model;

[0028] Figure 2 This is a cross-sectional view of the range hood according to an embodiment of the present utility model;

[0029] Figure 3 This is a schematic diagram of a centrifugal fan according to an embodiment of the present utility model;

[0030] Figure 4 This is a cross-sectional view (axial section, parallel to the impeller axis) of the centrifugal fan according to an embodiment of the present utility model;

[0031] Figure 5 for Figure 4 A magnified schematic diagram of part I;

[0032] Figure 6 This is a cross-sectional view (radial section, perpendicular to the impeller axis) of the centrifugal fan according to an embodiment of the present utility model;

[0033] Figure 7 This is a schematic diagram of the profile of the volute and clearance adjustment component of the centrifugal fan according to an embodiment of the present invention. Detailed Implementation

[0034] 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.

[0035] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They 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 utility model 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.

[0036] See Figures 1-6 A range hood includes a centrifugal fan 100, which may or may not be housed within a separate fan frame 200. In other words, the form of the range hood is not limited; it can be an existing side-draft, top-draft, or ceiling-mounted type.

[0037] The centrifugal fan 100 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 a first cover plate 11 and a second cover plate 12 spaced apart along the axis X of the impeller 2, and also includes an annular wall 13 disposed between the first cover plate 11 and the second cover plate 12. A first air inlet 111 is provided on the first cover plate 11, and a second air inlet 121 is provided on the second cover plate 12. The motor 3 is installed from one side of the second cover plate 12, that is, the motor 3 is installed through the second air inlet 121. Thus, the first air inlet 111 serves as the main air inlet, and the second air inlet 121 serves as the secondary air inlet. The first cover plate 11, the second cover plate 12, and the annular wall 13 together form an air outlet 14. A first collector 161 is provided at the first air inlet 111, and a second collector 162 is provided at the second air inlet 121.

[0038] The impeller 2 includes a front disc 21, a rear disc 22, and a plurality of blades 23 disposed between the front disc 21 and the rear disc 22. The blades 23 are arranged at circumferential intervals along the front disc 21 or the rear disc 22. The front disc 21 is close to the first cover plate 11 of the volute 1, and the rear disc 22 is close to the second cover plate 12 of the volute 1.

[0039] The centrifugal fan 100 also includes a gap adjustment unit. Since the centrifugal fan 100 is a dual-inlet fan in this embodiment, there are two gap adjustment units, referred to as the first gap adjustment component 41 and the second gap adjustment component 42. The first gap adjustment component 41 is located on the side of the first cover plate 11 facing inwards from the volute 1 and is tightly fitted against the annular wall 13. The second gap adjustment component 42 is located on the side of the second cover plate 12 facing inwards from the volute 1 and is tightly fitted against the annular wall 13. Both the first gap adjustment component 41 and the second gap adjustment component 42 are equal-thickness components, meaning that their thickness along the circumference of the volute 1 and in the radial direction of the impeller 2 is equal. Figure 4 , Figure 5 As shown in the diagram, d1 and d2. When the centrifugal fan 100 is a single-inlet fan, there can be only one gap adjustment unit, located near the air inlet, or two can be installed.

[0040] The volute 1 also includes a volute tongue 15, whose position and configuration are the same as in the prior art. After the gas enters the volute 1 from the first air inlet 111 and the second air inlet 121, it flows out from the air outlet 14 of the volute 1. The volute tongue 15 is the most prone to backflow and mixing with the intake airflow, which deteriorates the flow and increases noise. The aerodynamic noise of the centrifugal fan is mainly generated at this point. A reasonable gap can greatly improve the above problems. Therefore, the first gap adjusting member 41 and the second gap adjusting member 42 are located downstream of the volute tongue 15, extending from the end of the volute tongue 15 downstream of the volute tongue 15. "Downstream of the volute tongue 15" refers to the side of the volute tongue 15 away from the air outlet 14. Here, as the circumferential distance from the volute tongue 15 increases, the air passage between the volute 1 and the impeller 2 gradually widens. That is to say, it extends along the annular wall 13 from the end of the volute tongue 15 away from the air outlet 14 in a direction away from the air outlet 14. The clearance between the volute tongue 15 and the outer circumference of the impeller 2 is t, which is typically 15–30 mm. d1 / t = 0.3–0.5, d2 / t = 0.3–0.5, and optionally d1 ≤ 8 mm, d2 ≤ 8 mm, to ensure sufficient safety clearance between the volute tongue 15 and the impeller 2. Since the second air inlet 121 is a secondary air inlet with a smaller air volume than the first air inlet 111, the clearance between the second clearance adjusting member 42 and the impeller 2 is smaller; that is, optionally, d2 > d1.

[0041] By adding a gap adjustment unit, a low-speed zone can be formed in the cavity between the front disc 21 and the rear disc 22 of the impeller 2 and their respective collectors, which effectively reduces the gas backflow at the gap between the collector and the impeller, improves the mixing of the intake gas and the backflow gas in the gap, reduces the axial velocity of the intake gas in the front and rear discs of the impeller, and improves the work capacity of the front and rear discs of the impeller.

[0042] See Figure 7The diagram shows the profiles of the volute 1 and the second clearance adjusting member 42, where point O is the center of the base circle of the volute 1 profile (helix), which is also the axis X of the impeller 2 (see axis X). Figure 3 A point on the circle. The line connecting the center point O to the starting point of the second gap adjusting member 42 near the volute tongue 15 is the first line L1, and the line connecting the center point O to the ending point of the second gap adjusting member 42 away from the volute tongue 15 is the second line L2. The angle between the first line L1 and the second line L2 is α, and the value of α ranges from 0 to 90°. Optionally, α = 30°. The above angle also applies to the first gap adjusting member 41, that is, the gap adjusting unit satisfies the above angle.

[0043] See also Figure 5 The axial thickness of the first gap adjusting member 41 along the X direction of the impeller 2 is δ. f The axial thickness of the second gap adjusting member 42 along the X direction of the impeller 2 is δ. b The total axial thickness of the two gap adjusting components is δ = δ f +δ b ;δ f and δ b The axial distances can be equal or unequal, depending on the operating conditions. The axial distance between the front disc 21 of the impeller 2 and the first cover plate 11 of the volute 1 is δ1, the axial distance between the rear disc 22 of the impeller 2 and the second cover plate 12 of the volute 1 is δ2, and the total axial clearance between the impeller 2 and the volute 1 is δ. 0＝ δ 1+ δ2, δ / δ0=δ f / δ1=δ b / δ2=a, where a ranges from 0 to 7.5. Optionally, a = 0.5, 1, 2, 4, or 7.3. When δ / δ0=δ f / δ1=δ b When / δ2=7.3, δ f +δ b =B, where B is the axial thickness of the volute 1.

[0044] The radial clearance between the annular wall 13 (volute profile) of the volute 1 and the impeller 2 is adjusted by changing the axial thickness of the clearance adjustment unit, thereby reducing backflow at the impeller 12 outlet. The reason for adjusting the radial clearance by adjusting the axial thickness is that, with the axial direction as the abscissa and the radial clearance as the ordinate, the ordinate changes accordingly from 0 to B. Assuming the initial profile (i.e., δ / δ0 = 0), the ordinate is a straight line (a constant value, such as 20 mm); when δ / δ0 = 1, the ordinate is divided into three straight lines: 12 mm (abscissa 0 - δ1), 20 mm (δ1 to B - δ2), and 12 mm (B - δ2 to B).

[0045] As the axial thickness ratio of the clearance adjustment unit increases, the backflow at the impeller 2 inlet and outlet first decreases and then increases upstream of the volute tongue (108°-270°), and continuously decreases downstream of the volute tongue (0°-108°). This means that adding the clearance adjustment unit can improve the impeller's work capacity. When δ / δ0 = 1, it can reduce operating noise by 1% and increase maximum airflow by 2%.

[0046] In summary, by setting up a gap adjustment unit, the impeller's work capacity can be improved, while the airflow backflow in the volute tongue region (the internal region of the volute) is solved. The arrangement and installation are highly feasible and can be used as part of the downstream features of the volute tongue.

Claims

1. A centrifugal fan, comprising: The volute (1) includes a first cover plate (11), a second cover plate (12), an annular wall (13) disposed between the first cover plate (11) and the second cover plate (12), and a volute tongue (15). The first cover plate (11), the second cover plate (12), and the annular wall (13) form an air outlet (14). Impeller (2) is installed inside volute (1); Its features are: The centrifugal fan also includes a gap adjustment unit that is at least adjacent to the air inlet of the centrifugal fan. The gap adjustment unit extends from the end of the volute tongue (15) away from the air outlet (14) in a direction away from the volute tongue (15). The gap adjustment unit is located on the side of the first cover plate (11) and / or the second cover plate (12) facing the inside of the volute (1). The gap adjustment unit is close to the annular wall (13).

2. The centrifugal fan according to claim 1, characterized in that: The gap adjustment unit is a component of equal thickness with equal thickness in the radial direction of the impeller (2).

3. The centrifugal fan according to claim 2, characterized in that: The gap between the volute tongue (15) and the outer periphery of the impeller (2) is t, and the ratio of the thickness dimension of the gap adjustment unit in the radial direction of the impeller (2) to t is 0.3 to 0.

5.

4. The centrifugal fan according to claim 3, characterized in that: The thickness of the gap adjustment unit in the radial direction of the impeller (2) is ≤8mm.

5. The centrifugal fan according to claim 1, characterized in that: The base circle of the volute (1) profile has a base circle center (O), and the angle between the two ends of the gap adjustment unit profile and the line connecting the base circle center (O) is α, and the value of α ranges from 0 to 90°.

6. The centrifugal fan according to claim 1, characterized in that: The centrifugal fan has an air inlet including a first air inlet (111) formed on the first cover plate (11) and a second air inlet (121) formed on the second cover plate (12). The gap adjustment unit has two parts, referred to as the first gap adjustment member (41) and the second gap adjustment member (42), respectively. The first gap adjustment member (41) is located on the side of the first cover plate (11) facing the inside of the volute (1), and the second gap adjustment member (42) is located on the side of the second cover plate (12) facing the inside of the volute (1).

7. The centrifugal fan according to claim 6, characterized in that: The thickness of the first gap adjusting member (41) in the radial direction of the impeller (2) is d1, and the thickness of the second gap adjusting member (42) in the radial direction of the impeller (2) is d2. The first air inlet (111) is the main air inlet, and the second air inlet (121) is the auxiliary air inlet. d1 and d2 also satisfy the following relationship: d2 > d1.

8. The centrifugal fan according to claim 6, characterized in that: The axial thickness of the first gap adjusting member (41) along the axis (X) of the impeller (2) is δ. f The axial thickness of the second gap adjusting member (42) along the axis (X) of the impeller (2) is δ. b The total axial thickness of the two gap adjusting components is δ = δ f +δ b ; The impeller (2) includes a front disc (21) and a rear disc (22). The front disc (21) is close to the first cover plate (11) of the volute (1), and the rear disc (22) is close to the second cover plate (12) of the volute (1). The axial distance between the front disc (21) of the impeller (2) and the first cover plate (11) of the volute (1) is δ1, and the axial distance between the rear disc (22) of the impeller (2) and the second cover plate (12) of the volute (1) is δ2. The total axial clearance between the impeller (2) and the volute (1) is δ. 0＝ δ 1+ δ2; And it satisfies the following relationship: δ / δ0=δ f / δ1=δ b / δ2=a, where the value of a ranges from 0 to 7.

5.

9. The centrifugal fan according to claim 1, characterized in that: The total axial thickness of the gap adjustment unit is δ; The impeller (2) includes a front disc (21) and a rear disc (22). The front disc (21) is close to the first cover plate (11) of the volute (1), and the rear disc (22) is close to the second cover plate (12) of the volute (1). The axial distance between the front disc (21) of the impeller (2) and the first cover plate (11) of the volute (1) is δ1, and the axial distance between the rear disc (22) of the impeller (2) and the second cover plate (12) of the volute (1) is δ2. The total axial clearance between the impeller (2) and the volute (1) is δ. 0＝ δ 1+ δ2; And it satisfies the following relationship: the value range of δ / δ0 is 0 to 7.

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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