Mixed flow fans and duct fans

Abstract

This invention discloses a mixed-flow fan and a ducted fan. The mixed-flow fan includes: a volute; an impeller disposed inside the volute, the impeller comprising multiple blades, the number of blades being N; and the maximum diameter of the volute being E, wherein 81.54ln(N) + 20 ≤ E ≤ 81.54ln(N) + 60, and 2 ≤ N ≤ 22. The mixed-flow fan and ducted fan of this invention effectively solve the problem of low energy efficiency in existing mixed-flow fans.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically, to a mixed-flow fan and a duct fan. Background Technology

[0002] Ductless air conditioners are a type of air conditioner. To improve comfort, some ductless air conditioners use a top-discharge cooling and bottom-discharge heating method, which can achieve waterfall-style cooling and carpet-style heating. To achieve this air outlet method, the air outlet of the ductless air conditioner needs to be reversible. Among the existing ductless air conditioners with reversible air outlet, cross-flow fans and centrifugal fans are usually used. However, due to the design of the fan blades, the airflow direction cannot be reversed after reversing. Therefore, at least two fans must be set up, one responsible for forward air outlet and one responsible for reverse air outlet. This not only makes the duct fan structure larger but also increases the cost.

[0003] To reduce costs, fans need to be miniaturized. Mixed-flow fans are a type of fan that falls between axial and centrifugal fans. The impeller of a mixed-flow fan causes the air to undergo both centrifugal and axial motion. The airflow within the casing combines both axial and centrifugal motions, hence the name "mixed-flow." Moreover, mixed-flow fans can not only be made smaller in size but also maintain the correct airflow direction and pressure.

[0004] The impeller and volute design of existing mixed-flow fans are unreasonable, resulting in low energy efficiency. Summary of the Invention

[0005] This invention provides a mixed-flow fan and a duct fan to solve the problem of low energy efficiency of mixed-flow fans in the prior art.

[0006] To achieve the above objectives, the present invention provides a mixed-flow fan, comprising: a volute; an impeller disposed inside the volute, the impeller comprising multiple blades, the number of blades being N; and the maximum diameter of the volute being E, wherein 81.54ln(N)+20≤E≤81.54ln(N)+60, 2≤N≤22.

[0007] Furthermore, the volute is provided with an air inlet and an air outlet; the distance between the air inlet and the air outlet is A, the maximum diameter of the volute is E, and the ratio of A / E ranges from 0.76 to 0.88.

[0008] Furthermore, the maximum diameter of the impeller is D, and the relationship between E and D is 1.1 to 1.25.

[0009] Furthermore, multiple leaves include multiple long leaves and multiple short leaves.

[0010] Furthermore, the volute is a spherical structure, and the maximum diameter of the volute is equal to the diameter of the spherical structure.

[0011] Furthermore, the volute has air inlets and air outlets on the two bottom surfaces of the table tennis table.

[0012] Furthermore, the line connecting the center of the air inlet and the center of the air outlet is collinear with the axis of the impeller.

[0013] Furthermore, the surface of the blade has pits and / or protrusions.

[0014] Furthermore, N = 6, or N = 7, or N = 8.

[0015] Furthermore, the maximum diameter E of the volute ranges from 150mm to 250mm.

[0016] According to another aspect of the present invention, a duct fan is provided, comprising the aforementioned mixed-flow fan.

[0017] Furthermore, the mixed-flow fan is rotatably installed inside the duct unit.

[0018] With a fixed fan size, the number of blades can be determined using the above formula, resulting in a mixed-flow fan with superior performance. Analysis of the principle and simulation results clearly show that when the maximum diameters of the blades and volute meet the limits defined in this invention, the performance of the mixed-flow fan is significantly improved, with a marked increase in airflow, unlike the significant decrease seen in existing technologies. This demonstrates that the improvement in the mixed-flow fan effectively increases the fan's airflow. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal structure of the impeller of a mixed-flow fan according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of a mixed-flow fan according to an embodiment of the present invention;

[0021] Figure 3 This is a three-dimensional schematic diagram of the impeller of the mixed-flow fan according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the blade structure of the impeller of the mixed-flow fan according to an embodiment of the present invention. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0024] In existing mixed-flow fans, the volute shape is mostly cylindrical, and the duct shape is relatively fixed. Therefore, most improvements to existing mixed-flow fans focus on the impeller blade shape or the number of blades to increase airflow and improve energy efficiency. However, after studying airflow principles and analyzing simulation data, the applicant discovered that simply improving the blade shape and number has a very limited impact on the airflow of mixed-flow fans. Instead, the relationship between the number of blades and the overall structure of the mixed-flow fan, which has been overlooked in this field, is a crucial area for effectively improving airflow.

[0025] See Figures 1 to 4 As shown, an embodiment of the present invention provides a mixed-flow fan, which includes a volute 10 and an impeller 20. The impeller 20 is disposed inside the volute 10 and includes a plurality of blades 21, the number of which is N. The maximum diameter of the volute 10 along the radial direction of the impeller 20 is E, wherein 81.54ln(N)+20≤E≤81.54ln(N)+60, and 2≤N≤22.

[0026] For a given size, there may be more than one optimal number of blades. When the overall size of the fan is small, an excessive number of blades, while increasing the overall work capacity, also increases the fan's flow resistance. Finding a balance between these two factors is key to improving fan performance. When the overall size of the fan is large, too few blades will significantly limit further improvements in overall performance; a balance point also exists. Simulation experiments were conducted on the mixed-flow fan of this embodiment, varying the number of blades N. The simulation results are as follows:

[0027] N E(mm) Rotational speed (rpm) <![CDATA[Calculated air volume (m 3 / h)]]> Calculate the pressure head (Pa). 5 200 2200 502 82.7 6 200 2200 510 90.4 7 200 2200 514 91.5 8 200 2200 512 90.6

[0028] When E is 200mm, it significantly exceeds the corresponding size range (151-191mm) for 5 blades. Therefore, as shown in the table above, the calculated head of the 5-blade fan is lower at the same rotational speed, resulting in a significant decrease in airflow. This is because the insufficient number of blades in the larger size leads to lower work capacity. When the impeller has 6, 7, or 8 blades, the data shows that the E value of 200mm is within the optimal size range. Therefore, the capabilities of the three blade types are quite similar, including work capacity and airflow. With a fixed fan size, the number of blades can be determined using the above formula. This mixed-flow fan structure exhibits superior performance. The analysis principle and simulation results clearly show that when the maximum diameter of the blades and volute meets the limits defined in this invention, the performance of the mixed-flow fan is significantly improved, and the airflow is significantly increased, rather than the significant decrease seen in existing technologies. This demonstrates that the improvement of the mixed-flow fan effectively increases the airflow.

[0029] Preferably, the volute 10 is provided with an air inlet and an air outlet; the distance between the air inlet and the air outlet is A, and the ratio of A / E ranges from 0.76 to 0.88. Here, distance A can also be understood as the length of the volute 10. Figure 2 In the vertical direction shown, the length of the volute 10 is A. A and E determine the size of the outer spherical shell of the volute and the inlet and outlet areas of the fan. When the value of A is large, to meet the shape requirements of the spherical shell, the inlet and outlet areas of the fan will inevitably be reduced, thus affecting the fan performance. When the value of A is small, it means that the size of the fan impeller will be limited, which will also affect the fan's work capacity. A simulation experiment was conducted on the mixed-flow fan in this example, changing the value of A / E. The simulation results are as follows:

[0030] A / E Rotational speed (rpm) <![CDATA[Calculated air volume (m 3 / h)]]> Impeller head (Pa) Diffusion loss (Pa) 0.75 2200 489 126.4 39.4 0.76 2200 494 126.3 38.7 0.83 2200 510 126.8 36.2 0.88 2200 493 115.5 53.2 0.9 2200 480 110.3 68.5

[0031] As can be seen from the table above, when the A / E value is too small, the airflow is severely reduced, making it difficult for the impeller to perform its work. When the A / E value is too large, the reduced inlet and outlet area of ​​the fan leads to increased flow resistance, excessive drop in impeller head, and significant diffusion losses, resulting in a more severe airflow reduction and hindering the improvement of fan performance.

[0032] The maximum diameter of impeller 20 is D, and the relationship between E and D is 1.1 to 1.25. The maximum diameter of impeller 20 is the maximum diameter of the blades in the radial direction of the impeller. Due to the special shape of the blades, the point where the blades are widest is used as the point for determining the maximum diameter D. See also... Figure 2 As shown, the maximum diameter E of the volute 10 directly determines the shape of the volute of the mixed-flow fan, and the value of the maximum diameter E also has a corresponding relationship with the impeller 20. That is, controlling the gap between the impeller 20 and the volute in the radial direction within a certain range can increase the airflow of the mixed-flow fan. A simulation experiment was conducted on the mixed-flow fan in this example, changing the value of E / D. The simulation results are as follows:

[0033] E / D Rotational speed (rpm) <![CDATA[Calculated air volume (m 3 / h)]]> Impeller head (Pa) Diffusion loss (Pa) 1.04 2200 496 123.4 58.4 1.10 2200 502 124.7 41.6 1.19 2200 510 126.8 36.2 1.25 2200 498 120.3 40.2

[0034] As airflow passes through the impeller and performs work, it begins to carry high dynamic pressure. This dynamic pressure needs sufficient space to be released, and a portion of it is converted into static pressure to continue flowing. When the E / D ratio is too small, there is insufficient space for pressure release, which leads to a smaller ratio of dynamic pressure to static pressure, resulting in a larger diffusion loss in the fan and ultimately a lower overall air volume. Conversely, when the E / D ratio is too large, it further increases the overall size of the fan and compresses the foundation size of other components, which is not conducive to improving the fan's performance.

[0035] Preferably, the multiple blades 21 include multiple long blades and multiple short blades. The multiple blades of different lengths can increase the air volume of the mixed-flow fan.

[0036] Since the mixed-flow fan in this embodiment is installed inside the ducted air conditioning unit, there are process requirements and structural matching requirements for the size and shape of the volute 10 of the mixed-flow fan. Therefore, the volute 10 of the mixed-flow fan is further improved to maximize the air volume of the mixed-flow fan while meeting the above requirements of the ducted air conditioning unit. In order to match the structural requirements of the ducted air conditioning unit, the volute 10 is a spherical frustum structure, and the maximum diameter of the volute 10 is equal to the diameter of the spherical frustum structure.

[0037] The volute 10 has an air inlet and an air outlet on its two bottom surfaces. The line connecting the center of the air inlet and the center of the air outlet is collinear with the axis of the impeller 20.

[0038] The surface of blade 21 has pits and / or protrusions. The pits and protrusions can improve airflow and increase air volume.

[0039] The maximum diameter E of the volute casing ranges from 150mm to 250mm. By defining this range, the adaptability of the mixed-flow fan in ducted air conditioning systems can be improved. Due to the installation environment and production conditions of ducted air conditioning systems, the maximum diameter of the volute casing needs to be kept at a suitable size to achieve optimal energy efficiency within limited dimensional requirements. Simultaneously, considering the number of blades placed within the internal space of the volute casing, the maximum diameter E should not be too small or too large; the aforementioned range satisfies the relevant balance between the volute casing diameter and the blade size.

[0040] This invention also provides an embodiment of a ducted air conditioner, which includes the mixed-flow fan described in the above embodiment, rotatably mounted inside the ducted air conditioner. A mixed-flow fan is a type of fan intermediate between an axial fan and a centrifugal fan. The impeller of the mixed-flow fan causes the air to undergo both centrifugal and axial motion, and the airflow within the casing combines both axial and centrifugal motions, hence the name "mixed-flow." Because mixed-flow fans can not only be made smaller in size but also maintain airflow direction and pressure, installing a mixed-flow fan inside a ducted air conditioner allows for reversible airflow direction, changing the outlet air direction—that is, air is discharged from the side in cooling mode and from the side in heating mode.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] Of course, the above are preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the basic principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A mixed-flow fan, characterized in that, include: volute (10); Impeller (20), the impeller (20) is disposed inside the volute (10), the impeller (20) includes a plurality of blades (21), the number of blades (21) is N; The maximum diameter of the volute (10) is E, where 81.54ln(N)+20≤E≤81.54ln(N)+60, 2≤N≤22.

2. The mixed-flow fan according to claim 1, characterized in that, The volute (10) is provided with an air inlet and an air outlet; The distance between the air inlet and the air outlet is A, the maximum diameter of the volute (10) is E, and the ratio of A / E ranges from 0.76 to 0.

88.

3. The mixed-flow fan according to claim 2, characterized in that, The maximum diameter of the impeller (20) is D, and the relationship between E and D is 1.1 to 1.

25.

4. The mixed-flow fan according to claim 3, characterized in that, The plurality of leaves (21) includes a plurality of long leaves and a plurality of short leaves.

5. The mixed-flow fan according to claim 3, characterized in that, The volute (10) is a table ball structure, and the maximum diameter of the volute (10) is equal to the diameter of the table ball structure.

6. The mixed-flow fan according to claim 5, characterized in that, The volute (10) has the air inlet and the air outlet respectively located on the two bottom surfaces of the table.

7. The mixed-flow fan according to claim 2, characterized in that, The line connecting the center of the air inlet and the center of the air outlet is collinear with the axis of the impeller (20).

8. The mixed-flow fan according to claim 1, characterized in that, The surface of the blade (21) has pits and / or protrusions.

9. The mixed-flow fan according to claim 1, characterized in that, N = 6, or N = 7, or N = 8.

10. The mixed-flow fan according to claim 1, characterized in that, The maximum diameter E of the volute (10) ranges from 150mm to 250mm.

11. A ducted air conditioner, characterized in that, The mixed-flow fan includes any one of claims 1 to 10.

12. The duct air conditioner according to claim 11, characterized in that, The mixed-flow fan is rotatably mounted inside the duct unit.

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