Centrifugal fan

Abstract

The utility model provides a centrifugal fan, including volute still include: impeller, the impeller is provided with at least two groups, and at least two groups impeller follow the axial direction of volute, the middle disc is arranged between two groups of adjacent impeller, two groups of adjacent impeller are separated through the middle disc, and the import of middle disc is linked together with the import of volute, each group impeller is provided with several blades, and several blades are arrayed around the axial direction of volute, and the blade of two groups of adjacent impeller is staggered along the projection direction of blade. Through the mode for increasing the number of blade, increase the times of cutting the airflow that enters the volute, thereby improved the frequency of rotation noise, namely BPF noise, make BPF noise frequency far away from the hearing range of human ear, and then reduce the situation that the user hears the rotation noise. In addition, the blade that interlaces can break the shedding vortex that the blade tail edge produces, reduces the broadband noise of fan.

Description

Technical Field

[0001] This utility model specifically relates to a centrifugal fan. Background Technology

[0002] The high-speed rotation of conventional blades generates significant aerodynamic noise. Aerodynamic noise is one of the main noise sources in high-speed centrifugal fans, accounting for approximately 45% of the total fan noise. Aerodynamic noise includes rotational noise and vortex noise. Rotational noise is discrete noise, caused by the blades cutting through the airflow during rotation; this type of noise is commonly known as BPF noise, and its frequency is related to the number of blades: rotational speed RPM / 60 * number of blades z. Vortex noise is broadband noise, mainly referring to the noise generated by shedding vortices at the blade trailing edges. The former produces noise peaks, creating a harsh sound that is extremely uncomfortable for the human ear, while the latter produces significant wind noise, resulting in a poor user experience. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the shortcomings of the existing technology, such as large rotational noise and eddy current noise, and poor user experience, and to provide a centrifugal fan.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] A centrifugal fan, the centrifugal fan including a volute casing, the centrifugal fan further including:

[0006] Impeller, wherein at least two sets of impellers are provided, and at least two sets of impellers are arranged sequentially along the axial direction of the volute;

[0007] The middle disk is disposed between two adjacent groups of impellers, which are separated by the middle disk. The inlet of the middle disk is connected to the inlet of the volute. Each group of impellers is provided with several blades, which are arranged in an array around the axial direction of the volute. Along the projection direction of the blades, the blades of the two adjacent groups of impellers are staggered.

[0008] In this design, at least two sets of impellers are used, each containing several blades. Compared to a single set of impellers, the number of blades in the centrifugal fan is increased accordingly. This increased number of blades increases the number of times the airflow entering the volute is cut, thereby increasing the frequency of rotational noise (BPF noise). This pushes the BPF noise frequency away from the range of human hearing, reducing the amount of rotational noise heard by the user. Simultaneously, by staggering the blades of adjacent sets of impellers along their projection direction, the phase difference between the blades of adjacent sets is used to reduce the amplitude of BPF noise. These two factors combined achieve the goal of eliminating BPF noise.

[0009] In addition, the interlaced blades can disrupt the shedding vortices generated at the blade trailing edges, reducing the broadband noise of the fan and effectively reducing the aerodynamic noise of the centrifugal fan.

[0010] Preferably, along the projection direction of the blades, the phase angle of the blades of two adjacent sets of impellers is θ, where θ = 0 to 360 / n, and n is the number of blades.

[0011] In this solution, the above settings are used to reduce the impact of rotational noise, i.e., BPF noise.

[0012] Preferably, along the axial direction of the volute, the ratio of the outlet height of two adjacent sets of impellers is 0.7 to 1.

[0013] In this scheme, the above settings are used to reduce the turbulent kinetic energy at the blade trailing edge.

[0014] Preferably, the ratio of the inlet diameter of the volute to the inlet diameter of the middle disk is 1.35 to 1.45.

[0015] In this scheme, the above settings are used to ensure the air intake of each impeller group and to guarantee the aerodynamic performance of the fan.

[0016] Preferably, the volute includes an upper end cover and a lower end cover, and the impeller and the middle disk are both disposed between the upper end cover and the lower end cover. The cross-section of the upper end cover includes a first arc segment and a first straight segment, and the ratio of the radius of the first arc segment to the inlet diameter of the volute is 0.15 to 0.25.

[0017] In this scheme, the above settings are used to ensure the aerodynamic performance of the impeller near the inlet of the volute.

[0018] Preferably, the cross-section of the middle disk includes a second circular arc segment and a second straight line segment, wherein the radius of the second circular arc segment is 0.15 to 0.25 times the inlet diameter of the middle disk.

[0019] In this scheme, the above settings are used to ensure the aerodynamic performance of the impeller at the inlet, which is far from the volute.

[0020] Preferably, the cross-section of the middle plate includes a second straight segment.

[0021] In this design, even with only the second straight section, the aerodynamic performance of the impeller at the inlet far from the volute can still be guaranteed.

[0022] Preferably, the ratio of the inlet to outlet diameter of each impeller group is 0.25 to 0.8.

[0023] In this scheme, the above settings are used to ensure the aerodynamic performance of each impeller group.

[0024] Preferably, along the axial direction of the volute, the ratio of the inlet height of each set of impellers to the outer diameter of each set of impellers is 0.25 to 0.4.

[0025] In this scheme, the above settings ensure that the internal flow channel of each impeller has sufficient space, thus avoiding the impact on aerodynamic performance caused by low impeller height or small size.

[0026] Preferably, along the axial direction of the volute, the ratio of the outlet height of each set of impellers to the outer diameter of each set of impellers is 0.25 to 0.4.

[0027] In this scheme, the above settings ensure that the internal flow channel of each impeller has sufficient space, thus avoiding the impact on aerodynamic performance caused by low impeller height or small size.

[0028] The positive and progressive effects of this invention are as follows: By setting at least two sets of impellers, each set including several blades, the number of blades in the centrifugal fan is correspondingly increased compared to a single set of impellers. This increased number of blades increases the number of times the airflow entering the volute is cut, thereby increasing the frequency of rotational noise (BPF noise) and moving it away from the range of human hearing, thus reducing the frequency of rotational noise heard by the user. Simultaneously, by staggering the blades of adjacent sets of impellers along the blade projection direction, the phase difference between the blades of adjacent sets of impellers is used to reduce the amplitude of BPF noise. These two factors together achieve the goal of eliminating BPF noise.

[0029] In addition, the interlaced blades can disrupt the shedding vortices generated at the blade trailing edges, reducing the broadband noise of the fan and effectively reducing the aerodynamic noise of the centrifugal fan. Attached Figure Description

[0030] Figure 1 This is a perspective view of a centrifugal fan according to a preferred embodiment of the present invention.

[0031] Figure 2 This diagram shows the positional relationship between the blades of two adjacent sets of impellers in a preferred embodiment of the present invention.

[0032] Figure 3 This is a top view of a centrifugal fan according to a preferred embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram of the structure of a centrifugal fan according to a preferred embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] Snail shell 1

[0036] Top cover 11

[0037] First arc segment 111

[0038] First straight segment 112

[0039] Lower end cap 12

[0040] Impeller 2

[0041] Leaf 21

[0042] Mid-game 3

[0043] Second arc segment 32

[0044] Second straight segment 33

[0045] Bushing 4 Detailed Implementation

[0046] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0047] This embodiment provides a centrifugal fan, the specific structure of which is as follows: Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the centrifugal fan includes a volute 1, and the centrifugal fan also includes:

[0048] Impeller 2, at least two sets of impeller 2 are provided, and at least two sets of impeller 2 are arranged sequentially along the axial direction of volute 1;

[0049] The middle disk 3 is located between two adjacent groups of impellers 2. The two adjacent groups of impellers 2 are separated by the middle disk 3, and the inlet of the middle disk 3 is connected to the inlet of the volute 1. Each group of impellers 2 is provided with several blades 21, and the several blades 21 are arranged in an array around the axial direction of the volute 1. Along the projection direction of the blades 21, the blades 21 of the two adjacent groups of impellers 2 are staggered.

[0050] Specifically, this embodiment describes two sets of impellers 2, but this is not a limitation. Of course, in other embodiments, the number of impellers 2 can be three or more sets. Two sets of impellers 2 are arranged along the axial direction of the volute 1 inside the volute 1. The two sets of impellers 2 are arranged sequentially and separated by a central disk 3. Each set of impellers 2 includes several blades 21. The several blades 21 of each set of impellers 2 are arranged in an array around the axial direction of the volute 1, and adjacent blades 21 are spaced apart. Compared with only one set of impellers 2 in the volute 1, the number of blades of the centrifugal fan is increased accordingly. By increasing the number of blades 21, the number of times the airflow entering the volute 1 is cut is increased, thereby increasing the frequency of rotational noise, i.e., BPF noise, and making the BPF noise frequency far away from the range of human hearing, thus reducing the number of times users hear rotational noise.

[0051] Furthermore, in this embodiment, along the projection direction of the blades 21, the blades 21 of adjacent sets of impellers 2 are staggered. That is, along the projection direction of the blades 21, the blades 21 of the impeller 2 closest to the inlet of the volute 1 correspond to the blades 21 of the impeller 2 furthest from the inlet of the volute 1, and similarly, the blades 21 of the impeller 2 furthest from the inlet of the volute 1 correspond to the blades 21 of the impeller 2 closest to the inlet of the volute 1. By staggering the blades 21 of adjacent sets of impellers 2 along the projection direction of the blades 21, the phase difference between the blades 21 of adjacent sets of impellers 2 is used to reduce the BPF noise amplitude. Combined with increasing the number of blades 21, both factors achieve the purpose of eliminating BPF noise.

[0052] In addition, it is understandable that the interlaced blades 21 can disrupt the shedding vortices generated by the trailing edge of the blades 21, reduce the broadband noise of the fan, effectively reduce the aerodynamic noise of the centrifugal fan, and thus effectively reduce the aerodynamic noise of the centrifugal fan and improve the user experience.

[0053] In this embodiment, along the projection direction of the blade 21, the phase angle of the blades 21 of two adjacent sets of impellers 2 is θ, where θ = 0 to 360 / n, and n is the number of blades 21. By limiting the range of the phase angle θ, the influence of rotational noise, i.e., BPF noise, can be effectively reduced.

[0054] In this embodiment, the two sets of impellers 2 have the same number of blades 21. In other embodiments, the number of blades 21 in different sets of impellers 2 may be different. The blades 21 in this embodiment can be applied to injection molded fans and metal fans. Injection molded fans can be injection molded in layers and then laser welded. Metal fans can be assembled by insert riveting.

[0055] It is understood that in this embodiment, the blade shape and inlet / outlet angle of the impeller 2 near the inlet of the volute 1 and the impeller 2 far from the inlet of the volute 1 can be the same or different. On the basis of increasing the number of blades 21 and setting them staggered along the projection direction of the blades 21, it can also effectively reduce the noise of the centrifugal fan.

[0056] In this embodiment, along the axial direction of the volute 1, the ratio of the outlet heights of two adjacent sets of impellers 2 is 0.7 to 1.

[0057] Specifically, along the axial direction of the volute 1, the outlet height of the set of impellers 2 near the inlet of the volute 1 is b1, and the outlet height of the set of impellers 2 away from the inlet of the volute 1 is b2, where the value of b1 / b2 ranges from 0.7 to 1. This limits the ratio of the outlet heights of the two sets of impellers 2, thereby reducing the turbulent kinetic energy at the trailing edge of the blades 21. Compared to a fan with only one set of impellers 2 inside the volute 1, the fan with two sets of impellers 2 has a higher turbulent kinetic energy located in the middle disk 3, while the fan with only one set of impellers 2 inside the volute 1 has a higher turbulent kinetic energy located at the lower end cover of the fan. Furthermore, the turbulent kinetic energy in the middle disk is less than that at the lower end cover of the fan with only one set of impellers 2 inside the volute 1.

[0058] In this embodiment, the ratio of the inlet diameter of the volute 1 to the inlet diameter of the middle disk 3 is 1.35 to 1.45.

[0059] Specifically, the inlet diameter of the volute 1 is D1, and the inlet diameter of the intermediate disk 3 is D2, where the ratio of D1 to D2 ranges from 1.35 to 1.45. By limiting the ratio of the inlet diameter of the volute 1 to the inlet diameter of the intermediate disk 3, the inlet diameter of the intermediate disk 3, which is used to guide airflow to the impeller 2 located away from the inlet of the volute 1, is smaller than the inlet diameter of the volute 1 used to guide airflow to the impeller 2 located closer to the inlet of the volute 1. This ensures the ability of the impeller 2 located away from the inlet of the volute 1 to perform work on the airflow. Simultaneously, it guarantees the air intake volume of each set of impellers 2, ensuring the aerodynamic performance of the fan. It can be understood that in this embodiment, the inner diameter of the impeller 2 located away from the inlet of the volute 1 is larger than the inner diameter of the impeller 2 located closer to the inlet of the volute 1, in order to increase the work performed by the impeller 2 located away from the inlet of the volute 1.

[0060] In this embodiment, the volute 1 includes an upper end cover 11 and a lower end cover 12. The impeller 2 and the intermediate disk 3 are both disposed between the upper end cover 11 and the lower end cover 12. The cross-section of the upper end cover 11 includes a first arc segment 111 and a first straight segment 112. The ratio of the radius of the first arc segment 111 to the inlet diameter of the volute 1 is 0.15 to 0.25. By limiting the ratio of the radius of the first arc segment 111 to the inlet diameter of the volute 1, sufficient air intake for the impeller 2 near the inlet of the volute 1 is ensured, thereby satisfying the aerodynamic performance of the fan.

[0061] In this embodiment, the cross-section of the middle disk 3 includes a second circular arc segment 32 and a second straight line segment 33. The ratio of the radius of the second circular arc segment 32 to the inlet diameter of the middle disk 3 is 0.15 to 0.25. By limiting the ratio of the radius of the second circular arc segment 32 to the inlet diameter of the middle disk 3, sufficient air intake can be ensured for the impeller 2, which is far from the inlet of the volute 1, thereby satisfying the aerodynamic performance of the fan.

[0062] In another embodiment, the cross-section of the middle plate 3 includes a second straight segment 33.

[0063] Specifically, the cross-section of the middle disk 3 only includes the second straight segment 33. The middle disk 3 is actually a circular structure, and the smaller hole in the circular structure is the inlet of the middle disk 3. At this time, the inlet diameter of the volute 1 is D1, and the inlet diameter of the middle disk 3 is D2. The value range of D1 / D2 is still 1.35 to 1.45. This ensures the aerodynamic performance of the impeller 2, which is far from the inlet of the volute 1, even with only the second straight segment 33.

[0064] In this embodiment, the ratio of the inlet to outlet diameter of each impeller 2 is 0.25 to 0.8.

[0065] Specifically, the inner diameter of each impeller 2 is the inlet diameter of each impeller 2, and the outer diameter of each impeller 2 is the outlet diameter of each impeller 2. By limiting the ratio of the inner diameter to the outer diameter of the impeller 2, the aerodynamic performance of each impeller 2 is guaranteed.

[0066] In this embodiment, along the axial direction of the volute 1, the ratio of the inlet height of each impeller 2 to the outer diameter of each impeller 2 is 0.25 to 0.4.

[0067] Specifically, taking the group of impellers 2 near the inlet of the volute 1 as an example, the inlet height of impeller 2 is its height along the axial direction of the volute 1, and the outer diameter of impeller 2 is its outer edge dimension. By limiting the ratio of the inlet height of impeller 2 to the outer diameter of each group of impellers 2, sufficient space is ensured in the internal flow channel of the volute 1 where each group of impellers 2 is located, preventing the impellers from being too low in height or too small in size, which would affect the aerodynamic performance of the fan. The same principle applies to the group of impellers 2 further away from the inlet of the volute 1, and will not be elaborated further here.

[0068] In this embodiment, along the axial direction of the volute 1, the ratio of the outlet height of each impeller 2 to the outer diameter of each impeller 2 is 0.25 to 0.4.

[0069] Specifically, taking the group of impellers 2 near the inlet of the volute 1 as an example, the outlet height of impeller 2 is its height along the axial direction of the volute 1, and the outer diameter of impeller 2 is its outer edge dimension. By limiting the ratio of the outlet height of impeller 2 to the outer diameter of each group of impellers 2, sufficient space is ensured in the internal flow channel of the volute 1 where each group of impellers 2 is located, preventing the impellers from being too low in height or too small in size, which would affect the aerodynamic performance of the fan. The same principle applies to the group of impellers 2 further away from the inlet of the volute 1, and will not be elaborated further here.

[0070] In this embodiment, the centrifugal fan also includes a bushing 4, which is located at the axis of the volute 1 and is used to connect with the motor output shaft.

[0071] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A centrifugal fan comprising a volute, characterized by, The centrifugal fan also includes: Impeller, wherein at least two sets of impellers are provided, and at least two sets of impellers are arranged sequentially along the axial direction of the volute; The middle disk is disposed between two adjacent groups of impellers, which are separated by the middle disk. The inlet of the middle disk is connected to the inlet of the volute. Each group of impellers is provided with several blades, which are arranged in an array around the axial direction of the volute. Along the projection direction of the blades, the blades of the two adjacent groups of impellers are staggered.

2. The centrifugal fan of claim 1, wherein Along the projection direction of the blade, the phase angle of the blades of two adjacent sets of the impeller is θ, where θ = 0 to 360 / n, and n is the number of blades.

3. The centrifugal fan of claim 2, wherein Along the axial direction of the volute, the ratio of the outlet height of two adjacent sets of impellers is 0.7 to 1.

4. The centrifugal fan of claim 3, wherein The ratio of the inlet diameter of the volute to the inlet diameter of the middle disk is 1.35 to 1.

45.

5. The centrifugal fan of claim 4, wherein The volute includes an upper end cover and a lower end cover. The impeller and the middle disk are both disposed between the upper end cover and the lower end cover. The cross-section of the upper end cover includes a first arc segment and a first straight segment. The ratio of the radius of the first arc segment to the inlet diameter of the volute is 0.15 to 0.

25.

6. The centrifugal fan of claim 5, wherein The cross-section of the middle plate includes a second circular arc segment and a second straight line segment, wherein the radius of the second circular arc segment is 0.15 to 0.25 times the inlet diameter of the middle plate.

7. The centrifugal fan of claim 4, wherein The cross-section of the middle plate includes a second straight segment.

8. The centrifugal fan of claim 4, wherein The ratio of the inlet to outlet diameter of each impeller group is 0.25 to 0.

8.

9. The centrifugal fan of claim 8, wherein Along the axial direction of the volute, the ratio of the inlet height of each impeller group to the outer diameter of each impeller group is 0.25 to 0.

4.

10. The centrifugal fan of claim 9, wherein Along the axial direction of the volute, the ratio of the outlet height of each set of impellers to the outer diameter of each set of impellers is 0.25 to 0.4.

Images