An air outlet cover, an air outlet cover forming method, a fan assembly and a range hood

Abstract

The application discloses an air outlet cover, an air outlet cover forming method, a fan assembly and a range hood. The air outlet cover comprises an inlet for air flow to enter and an outlet for air flow to exit, and is characterized in that: from the inlet to the outlet, the cross-sectional area of the passage through which the air flow passes gradually increases with the increase of the height of the air outlet cover, and the change rate of the cross-sectional area changes from small to large. Compared with the prior art, the application has the advantages that: by changing the change rate of the cross-sectional area of the passage of the air outlet cover from small to large, the passage of the air outlet cover is more in line with the gas flow law at the outlet of the fan, and the resistance loss is reduced.

Description

Technical Field

[0001] This invention relates to power devices, and more particularly to an exhaust hood, a method for forming the exhaust hood, a fan assembly using the exhaust hood, and a range hood using the fan assembly. Background Technology

[0002] Multi-blade centrifugal fans are widely used in various household appliances such as air conditioners, range hoods, air purifiers, and exhaust fans due to their advantages such as compact structure, high pressure coefficient, large flow coefficient, and low noise. Currently, in the range hood industry, considering the limited space in kitchens, there is a certain demand from consumers for slimmer range hood models. Correspondingly, the fan design also needs to be adapted to a slimmer profile. "Slim" refers to a fan whose casing thickness is less than 140 mm, or whose outlet width is greater than its thickness.

[0003] The premise of thinner design is to maintain the performance of the fan system. While reducing the thickness of the fan system, measures such as increasing the impeller diameter and fan outlet width are usually taken to improve fan performance. Because the design of the fan system needs to consider performance and noise under different resistance conditions, the fan outlet area is usually controlled within a fixed and suitable range. Therefore, the smaller the fan thickness and the larger the fan outlet width, the greater the shape loss caused by the outlet shroud when the fan enters the duct. To reduce the transition loss of the outlet shroud, it can be heightened, but this is limited by installation space and increases costs.

[0004] From the perspective of facilitating the outflow of gas from inside the fan, the cross-sectional area of ​​the outlet hood should gradually increase from square to circular. This gradual decrease in air velocity increases the outlet static pressure, which helps overcome channel resistance, prevents external disturbances from worsening inside the fan, and improves the user experience. When the airflow first enters the outlet hood, the velocity is relatively high and the airflow is relatively concentrated. At this time, a rapid change in the cross-sectional area of ​​the channel is unfavorable. However, as the airflow progresses, in the later part of the outlet hood, the airflow velocity slows down and the airflow becomes relatively dispersed, allowing the rate of change of the channel cross-sectional area to increase relatively.

[0005] Currently, there are two main methods for generating the air hood shape by transitioning from a square to a circle. One method is to generate it by mixing lines and points (such as...). Figure 4 As shown), one type is generated by line-to-line mixing (such as...). Figure 5 (As shown). The methods described here are all modeling methods in Creo, representing different ways to generate the envelope surface of the windshield. "Line-to-point" generates a triangular surface by mixing lines and points, while "line-to-line" generates a quadrilateral surface by mixing lines. Figure 4 The cross-sectional area of ​​the air outlet duct shown in the figure first increases and then decreases with height, which does not conform to the gradual increase trend and is unfavorable. Figure 5Although the cross-sectional area of ​​the air outlet duct shown gradually increases with height, the mixing of lines is currently basically proportional to the length of the lines. This results in the rate of change of the cross-sectional area with height decreasing from large to small, which is disadvantageous and requires further design improvement. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a fan assembly that improves the fit between the air outlet shroud and the gas flow pattern at the outlet of the centrifugal fan, thereby reducing resistance loss.

[0007] The second technical problem to be solved by the present invention is to provide a method for forming the above-mentioned air outlet cover.

[0008] The third technical problem to be solved by the present invention is to provide a fan assembly with the above-mentioned air outlet shroud.

[0009] The fourth technical problem to be solved by the present invention is to provide a range hood that uses the above-mentioned fan assembly.

[0010] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: an air outlet hood, including an inlet for airflow to enter and an outlet for airflow to exit, characterized in that: from the inlet to the outlet, the cross-sectional area of ​​the channel through which the airflow passes through the air outlet hood gradually increases with the increase of the height of the air outlet hood, and the rate of change of the cross-sectional area increases from small to large.

[0011] By increasing the rate of change of the cross-sectional area of ​​the air outlet hood, the air outlet hood's channel better conforms to the flow pattern of the gas at the fan outlet, thus reducing resistance loss.

[0012] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a method for forming an air outlet hood as described above, wherein the air outlet hood is used to be installed at the air outlet of a centrifugal fan, characterized by comprising the following steps:

[0013] 1) Let the thickness of the air outlet of the centrifugal fan corresponding to the air outlet hood be a and the width of the air outlet be b. The projection of the center O of the outlet end face of the air outlet hood along the height direction onto the air outlet end face of the centrifugal fan coincides with the intersection of the diagonal of the air outlet end face of the centrifugal fan.

[0014] 2) Let α be the central angle of the arc segment corresponding to thickness a. The arc segment refers to the part of the outlet projection on the end face of the centrifugal fan outlet located between the diagonals, and this part is located between the two sides in the thickness direction of the outlet.

[0015] The rate of change of the cross-sectional area of ​​the air outlet channel with respect to height is k = (πr) 2Based on -ab) / h, the cross-sectional area of ​​the channel at position x of the outlet hood is Sx=ab+kx, where 0≤x≤h. Let α be the central angle of the outlet arc segment corresponding to thickness a at this position. max ;

[0016] 3) Make α satisfy: α < α max This gives us the circle corresponding to the exit.

[0017] 4) Mix the rectangular lines of the air outlet 21 and the circular lines of the outlet to obtain the envelope surface of the air outlet cover.

[0018] By reasonably controlling the central angle corresponding to the air outlet line, the cross-sectional area of ​​the generated hood channel can be made to increase with height, and the rate of change of the cross-sectional area with height can be made to increase from small to large.

[0019] Furthermore, in step 3), α also satisfies: This avoids the situation where an excessively small α value leads to significant separation due to wall compression during local airflow guidance, thus preventing the generation of vortex noise.

[0020] The technical solution adopted by the present invention to solve the third technical problem mentioned above is: a fan assembly, including a centrifugal fan, characterized in that: the air outlet hood as described above is disposed at the air outlet of the centrifugal fan.

[0021] The technical solution adopted by the present invention to solve the fourth technical problem mentioned above is: a range hood, characterized in that: it uses the fan assembly described above.

[0022] Compared with the prior art, the advantages of the present invention are: by making the rate of change of the cross-sectional area of ​​the air outlet hood channel increase from small to large, the air outlet hood channel is more in line with the flow law of the gas at the fan outlet and the resistance loss is reduced; by reasonably controlling the central angle corresponding to the air outlet line, the cross-sectional area of ​​the generated individual hood channels can increase with height, and the rate of change of the cross-sectional area with height increases from small to large. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the wind turbine assembly according to an embodiment of the present invention;

[0024] Figure 2 This is a side view of a wind turbine assembly according to an embodiment of the present invention;

[0025] Figure 3 This is a top view of the air outlet cover according to an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of an existing air outlet shroud;

[0027] Figure 5This is a schematic diagram of an existing air outlet shroud;

[0028] Figure 6 A schematic diagram comparing the rate of change of the cross-sectional area of ​​the exhaust shroud generated by different methods. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] See Figures 1-3 The image shows a fan assembly, including a centrifugal fan 1 and an air outlet shroud 2 disposed at the air outlet (not shown) of the centrifugal fan 1. The centrifugal fan 1 is preferably a thin multi-blade centrifugal fan. The above-mentioned fan assembly can be mainly used in range hoods, and of course, it can also be used in air conditioners, fresh air systems, etc.

[0032] The exhaust hood 2 has an inlet (not shown) for airflow entry and an outlet 21 for airflow exit. The inlet end of the exhaust hood 2 is connected to the centrifugal fan 1, and its shape matches the outlet of the centrifugal fan 1, generally being rectangular. The outlet 21 of the exhaust hood 2 is formed at the end of the exhaust hood 2 away from the centrifugal fan 1, and is generally circular to facilitate connection with the exhaust pipe. An airflow passage is formed inside the exhaust hood 2. The above structure is the same as in the prior art.

[0033] From the inlet to the outlet 21, the cross-sectional area of ​​the channel through which the airflow passes through the air outlet hood 2 gradually increases with the increase of the height of the air outlet hood 2, and the rate of change of the channel cross-sectional area increases from small to large, that is, it increases faster and faster.

[0034] To generate the aforementioned air outlet hood 2, firstly, let the thickness of the centrifugal fan 1's outlet be *a*, the width of the centrifugal fan 1's outlet be *b*, the radius of the outlet 21 of the air outlet hood 2 be *r*, and the height of the air outlet hood 2 be *h*. The projection of the center O of the outlet hood 2's end face along the height direction onto the outlet end face of the centrifugal fan 1 is intersected by the diagonal line of the outlet end face of the centrifugal fan 1 (in...). Figure 3 (In the image shown by a slanted dashed line) The intersection points coincide. When the lines are generated by mixing the two lines (where the two lines refer to the rectangle at the inlet and the circle at the outlet 21, respectively), the central angle of the arc segment of the outlet 21 corresponding to the thickness a (the part of the projection of the outlet 21 on the outlet end face of the centrifugal fan 1 located between the two diagonals, and this part located between the two sides in the thickness direction of the outlet) is denoted as α, which is equivalent to the angle between the projection of the center O and the two endpoints of the outlet end face in the thickness direction being α.

[0035] Secondly, when the rate of change of the cross-sectional area (horizontal section) of the air outlet hood 2 channel with height remains constant (the cross-sectional area gradually increases from bottom to top as the height increases), its rate of change k = (πr 2 -ab) / h, the cross-sectional area of ​​the channel at position x of the air outlet hood 2 is Sx=ab+kx, where 0≤x≤h. The air outlet hood is generated by controlling the central angle α of the arc segment corresponding to thickness a, so that the cross-sectional area of ​​the channel at position x is Sx. Let the central angle α of the arc segment corresponding to thickness a be denoted as α. max The definition of an arc segment is the same as above, when α < α max At that time, the cross-sectional area of ​​the air outlet hood 2 gradually increases with height, and the rate of change of the cross-sectional area with height increases from small to large. Of course, too small α is also unfavorable, as it will cause significant separation due to wall compression during local airflow guidance, generating vortex noise. The angle β between the line connecting the endpoint of thickness α and the endpoint of its corresponding arc segment and the height direction should not exceed 15°.

[0036] By making A circular shape is obtained for exit 21;

[0037] Finally, by combining the rectangle of the air outlet, the envelope surface of the air outlet cover 2 is obtained by mixing the lines of these two lines.

[0038] In a specific embodiment, the thickness a = 110 mm, the width of the air outlet b = 200 mm, the radius of the outlet 21 r = 88.8 mm, the height of the air outlet hood h = 150 mm, and α = 30°. The cross-sectional area of ​​the air outlet hood channel generated in different ways is compared in Table 1 below. The cross-sectional area of ​​the air outlet hood channel generated using the method of this invention, with line-to-line hybrid generation, gradually increases with height, and the rate of change of the cross-sectional area with height increases from small to large. See also the corresponding... Figure 6The lines from top to bottom correspond to "line-to-point mixing", "line-to-line mixing by length in proportion", and "line-to-line mixing method of the present invention", respectively. The horizontal axis represents the height (mm) and the vertical axis represents the channel cross-sectional area (mm²). 2 Actual test results also showed better performance than the other two methods (reduced drag loss).

[0039] Table 1 Comparison of height and cross-sectional area of ​​air hoods generated by different methods

[0040]

[0041]

Claims

1. A method for forming an air outlet casing for being arranged at an air outlet of a centrifugal fan (1), said air outlet casing comprising an inlet for air flow to enter and an outlet (21) for air flow to exit, characterized in that: From the inlet to the outlet (21), the cross-sectional area of the passage through which the air flow of the air outlet shroud passes gradually increases with the increase of the height of the air outlet shroud, and the change rate of the cross-sectional area changes from small to large; The forming method comprises the following steps: 1) Record the thickness a and the width b of the air outlet of the centrifugal fan (1) corresponding to the air outlet shroud, and the projection of the center O of the end surface of the outlet (21) of the air outlet shroud on the height direction on the outlet end surface of the centrifugal fan (1) coincides with the intersection point of the diagonal lines of the outlet end surface of the centrifugal fan (1); 2) Record the central angle α of the outlet (21) corresponding to the thickness a, wherein the circular arc segment refers to the part of the projection of the outlet (21) on the outlet end surface of the centrifugal fan (1) between the diagonal lines, and the part is between the two sides in the thickness direction of the air outlet; The change rate k = (πr 2 -ab) / h is kept consistent with the change rate of the cross-sectional area of the passage of the air outlet cover with the height, and the cross-sectional area of the passage at the height x of the air outlet cover is Sx = ab + kx, where 0 ≤ x ≤ h, and the central angle of the outlet (21) circular arc segment corresponding to the thickness a is α max ; 3) so that a satisfies: a < a max thereby obtaining a circle corresponding to the outlet (21); 4) Mix the rectangular line of the air outlet and the circular line of the outlet (21), and then obtain the envelope curved surface of the air outlet shroud.

2. The method of claim 1, wherein: In step 3), a also satisfies:

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