A noise-reducing centrifugal fan structure

Abstract

The application discloses a noise reduction type centrifugal ventilator structure and relates to the technical field of centrifugal fans. A first volute tongue part is arranged at the connecting position of an air outlet and a shell, a second volute tongue part is arranged at the tail end of the first volute tongue part, the second volute tongue part is inclined to the side close to an impeller, the gap between the volute tongue and the impeller is further reduced, the gas accelerated by the centrifugal force of the impeller is prevented from entering the shell again through the gap, the operation efficiency of the fan is affected, a plurality of flow guide pieces are equidistantly arranged on the side close to the impeller of the second volute tongue part, and a flow guide channel is formed between two adjacent flow guide pieces. The width of the flow guide piece gradually increases along the gas flow direction, so that the flow guide channel gradually decreases along the gas flow direction. When part of the gas enters the shell through the gap, the flow speed of the gas can be improved by using the flow guide channel, pressure exchange is prevented from occurring between the gas entering the shell through the volute tongue and the impeller and the accelerated gas in the shell, and periodic pulses are formed.

Description

Technical Field

[0001] This invention relates to the field of centrifugal fan technology, specifically a noise-reducing centrifugal fan structure. Background Technology

[0002] Centrifugal fans are fluid machines widely used in industries such as construction, air conditioning, mining, and tunnel ventilation. Their main function is to pressurize and transport gas through the centrifugal force generated by the rotation of the impeller. However, centrifugal fans generate significant noise pollution during operation, affecting the working environment and the health of personnel. Therefore, noise reduction technology has become an important direction for the design and optimization of centrifugal fans.

[0003] Chinese invention patent (CN111997935A) discloses a noise reduction volute tongue structure and a centrifugal fan. Specifically, the volute tongue structure includes a volute tongue body formed by the shell wall at the connection between the volute and the air outlet, multiple protrusions on the top of the volute tongue body, the multiple protrusions being distributed sequentially along the axial direction of the volute, and an airflow channel for airflow to pass through is provided between adjacent protrusions.

[0004] In existing technologies, protrusions are placed at the volute tongue to reduce the pressure gradient of the airflow near the volute tongue and suppress the superposition of noise in the volute tongue area, thereby reducing the noise of the centrifugal fan. However, the protrusions can only reduce a portion of the pressure gradient. After the airflow collides with the volute tongue, the airflow velocity decreases, resulting in a large velocity difference between some airflow and the accelerated airflow after it re-enters the volute, which in turn increases the pressure difference. Therefore, how to reduce the gas pressure difference and velocity difference at the volute tongue to achieve noise reduction has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a noise-reducing centrifugal fan structure to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A noise-reducing centrifugal fan structure includes a housing and an impeller driven to rotate inside the housing by a drive component. The distance between the inner wall of the housing and the outer edge of the impeller gradually increases along the rotation direction of the impeller. This is to avoid excessive noise caused by a large pressure gradient in the airflow inside the housing. The housing has an air inlet and an air outlet in the axial and radial directions, respectively. The axially installed air inlet allows outside air to enter the housing and is discharged through the radially installed air outlet under the centrifugal force generated by the impeller rotation. A rectifier is provided at the air inlet to guide the inflowing air. The design of the rectifier makes the airflow into the housing smoother and guides the flow direction of the air into the housing, eliminating airflow vortices, reducing the impact between the airflow and the impeller, thereby reducing noise and improving the operating efficiency of the fan.

[0008] A first volute tongue is provided at the connection between the air outlet and the housing. A second volute tongue is provided at the end of the first volute tongue. The second volute tongue is smoothly connected to the first volute tongue on the side near the air outlet to avoid sudden changes in airflow velocity at the air outlet due to sudden changes in the cross-section of the air outlet. The second volute tongue is inclined towards the side near the impeller to further reduce the gap between the volute tongue and the impeller, preventing the gas accelerated by the centrifugal force of the impeller from re-entering the housing through the gap and affecting the operating efficiency of the fan. Several flow guides are provided at equal intervals on the side of the second volute tongue near the impeller, and a flow guide channel is formed between two adjacent flow guides.

[0009] The width of the guide component gradually increases along the gas flow direction, causing the guide channel to gradually decrease along the gas flow direction. The purpose is to increase the gas velocity when a small portion of the gas re-enters the housing through the gap, thereby preventing pressure exchange between the gas entering the housing through the volute tongue and impeller and the accelerated gas inside the housing, which would otherwise form periodic pulses and achieve noise reduction.

[0010] According to the above technical solution, a resonant cavity is provided inside the first volute tongue. A resonant plate is installed inside the resonant cavity along the radial direction of the shell through a connector. When the gas accelerated by the centrifugal force of the impeller impacts the volute tongue, the resonant cavity and the resonant plate inside it vibrate, thereby canceling the overall vibration of the volute tongue and reducing the noise generated by the airflow impacting the volute tongue at the air outlet.

[0011] According to the above technical solution, the resonant cavity is in a vacuum state. By evacuating the resonant cavity, the propagation of sound generated by the vibration of the resonant plate inside the resonant cavity is blocked. The connector is an elastic connector, which is also intended to reduce the propagation of sound generated by the vibration of the resonant plate, thereby achieving the effect of noise reduction.

[0012] According to the above technical solution, the rectifier includes a first rectifier and a second rectifier. The first rectifier and the second rectifier are coaxially mounted at the air inlet. The diameter of the second rectifier is smaller than that of the first rectifier. The second rectifier is located inside the first rectifier. Both the first rectifier and the second rectifier are streamlined to reduce the impact generated when the gas enters the housing. A flow guide is coaxially mounted inside the housing with the impeller, the air inlet, and the rectifier.

[0013] Gas entering the housing through the gap between the first and second shrouds diffuses to both sides of the impeller and is accelerated by the centrifugal force of the high-speed rotating impeller. Gas entering the housing through the second shroud is guided to the guide component, eliminating the intake vortex generated by the gas entering the housing through the air inlet, thereby reducing noise.

[0014] According to the above technical solution, the drainage component includes a drainage seat, a drainage cavity, a guide cone, and a guide hole;

[0015] The airflow guide seat is installed inside the impeller and is used to guide the airflow entering the housing through the second rectifier, avoiding the generation of intake vortices and thus reducing noise. The airflow guide seat has an airflow cavity on the side facing the rectifier, allowing the airflow to enter the airflow cavity. A guide cone is installed inside the airflow cavity to split the airflow entering the airflow cavity. A guide hole is opened on the side wall of the airflow guide seat. The airflow cavity and the guide cone are used to guide the airflow to the guide hole, and then guide the airflow to the impeller position through the guide hole, thereby improving the operating efficiency of the fan.

[0016] According to the above technical solution, the flow guide rotates synchronously with the impeller, and the flow guide hole is bent along the impeller rotation direction. When the gas enters the flow guide chamber, under the rotation of the flow guide seat, the gas flows out through the flow guide hole, so that the initial flow direction of the gas is the same as the impeller rotation direction, thereby improving the operating efficiency of the fan. Furthermore, since the flow guide hole is bent along the impeller rotation direction, pre-swirl air intake is achieved, reducing the impact of airflow on the impeller and thus reducing noise.

[0017] According to the above technical solution, the impeller is composed of a disk and blades. The blades are backward-curved blades, forming an arc-shaped convex surface and an arc-shaped concave surface. A turning part is provided at the trailing edge of the blade. A flow-guiding hole is opened at the turning part and the position of the arc-shaped convex surface, penetrating the blade. Through the design of the flow-guiding hole, some gas can flow through the flow-guiding hole when the blade rotates, thereby realizing that there is also gas flow at the trailing edge of the arc-shaped concave surface. This reduces the possibility of Karman vortex street generated due to airflow boundary layer separation, thereby avoiding pressure fluctuations caused by alternating vortex shedding and reducing the possibility of noise generation.

[0018] According to the above technical solution, the angle formed by the surface of the turning part and the surface of the arc-shaped convex surface is an obtuse angle. Since the drainage hole is installed at the position of the turning part and the arc-shaped convex surface, the air flow rate through the drainage hole can be further increased.

[0019] According to the above technical solution, the central axis of the end of the guide hole is on the same axis as the central axis of the drainage hole. When the gas flows out through the guide hole, a part of the gas will directly reach the arc concave surface position through the drainage hole, thereby ensuring the gas volume at the tail edge of the arc concave surface and avoiding the generation of Karman vortex street due to boundary layer separation. At the same time, it can also reduce the impact of airflow on the blades and realize the noise reduction treatment of the fan.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention provides a second volute tongue and equally spaced guide elements on the side of the second volute tongue near the impeller. This allows the airflow, accelerated by centrifugal force, to partially enter the housing. The guide elements and the gradually decreasing diameter guide channels formed by them further accelerate the airflow, thereby reducing the velocity difference between the airflow entering the housing through the volute tongue and the originally accelerated airflow inside the housing. This reduces the impact between the airflows and thus reduces noise. At the same time, the design of the resonant cavity and resonant plate weakens the vibration caused by the impact between the airflow and the volute tongue, further reducing noise.

[0022] 2. The present invention, through the design of the rectifier and the guide, can guide the airflow entering the casing, so that part of the airflow is directly accelerated by the centrifugal force of the impeller, and the other part of the airflow is guided by the guide and then accelerated by the centrifugal force of the impeller. This can eliminate the intake vortex, reduce the impact between the airflow and the impeller, thereby reducing noise and improving the operating efficiency of the fan.

[0023] 3. This invention achieves pre-swirl intake by bending the guide hole, reducing the impact of airflow on the impeller and thus reducing noise. At the same time, the central axis of the end of the guide hole is on the same axis as the central axis of the guide hole. When the gas flows out through the guide hole, some of the gas will directly reach the arc-shaped concave surface through the guide hole, thus ensuring the gas volume at the trailing edge of the arc-shaped concave surface and avoiding the generation of Karman vortex street due to boundary layer separation. At the same time, it can also reduce the impact of airflow on the blades, thus achieving noise reduction of the fan. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a noise-reducing centrifugal fan according to the present invention;

[0025] Figure 2 This is a schematic diagram of the impeller installation structure in a noise-reducing centrifugal fan structure according to the present invention;

[0026] Figure 3 This is a cross-sectional view of the structure of a noise-reducing centrifugal fan according to the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the first volute tongue and the second volute tongue in the structure of a noise-reducing centrifugal fan of the present invention;

[0028] Figure 5 This is a schematic diagram of the flow guide component in a noise-reducing centrifugal fan structure according to the present invention;

[0029] Figure 6 This is a schematic diagram of the installation structure of the resonant cavity and resonant plate in a noise-reducing centrifugal fan structure according to the present invention;

[0030] Figure 7 This is a schematic diagram showing the installation positions of the rectifier and guide components in the structure of a noise-reducing centrifugal fan according to the present invention.

[0031] Figure 8 This is a schematic diagram of the rectifier component in a noise-reducing centrifugal fan structure according to the present invention;

[0032] Figure 9 This is a schematic diagram of the airflow guidance at the air inlet in the structure of a noise-reducing centrifugal fan according to the present invention;

[0033] Figure 10 This is a schematic diagram of the air intake component in a noise-reducing centrifugal fan structure according to the present invention;

[0034] Figure 11 This is a cross-sectional view of the air intake component in the structure of a noise-reducing centrifugal fan according to the present invention;

[0035] Figure 12 This is a first-view view of the blades in the structure of a noise-reducing centrifugal fan according to the present invention;

[0036] Figure 13 This is a second-view view of the blades in a noise-reducing centrifugal fan structure according to the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Shell;

[0039] 201. Wheel; 202. Blade; 203. Arc-shaped convex surface; 204. Arc-shaped concave surface; 205. Turning point; 206. Drainage hole;

[0040] 3. Drive components; 4. Air inlet;

[0041] 501. First fairing; 502. Second fairing;

[0042] 6. Air outlet; 7. First volute tongue; 8. Second volute tongue; 9. Air guide; 10. Air guide channel; 11. Resonance cavity; 12. Resonance plate; 13. Connecting component;

[0043] 1401, Drainage seat; 1402, Drainage cavity; 1403, Guide cone; 1404, Guide hole. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example: Figures 1-3 As shown, this invention provides a noise-reducing centrifugal fan structure, including a housing 1 and an impeller driven to rotate inside the housing 1 by a drive component 3. The drive component 3 can be a motor, which can be directly connected to the impeller via a key or connected to the impeller via a belt drive. The distance between the inner wall of the housing 1 and the outer edge of the impeller gradually increases along the rotation direction of the impeller. This is to avoid excessive noise caused by a large pressure gradient generated by the airflow inside the housing 1. The housing 1 has an air inlet 4 and an air outlet 6 in the axial and radial directions, respectively. The axially installed air inlet 4 allows external air to enter the housing 1 and is discharged through the radially installed air outlet 6 under the centrifugal force generated by the rotation of the impeller. A rectifier is provided at the air inlet 4 to guide the inflowing air. The design of the rectifier makes the airflow entering the housing 1 smoother and guides the flow direction of the air entering the housing 1, eliminating airflow vortices, reducing the impact between the airflow and the impeller, thereby reducing noise and improving the operating efficiency of the fan.

[0046] like Figures 4-6 As shown, a first volute tongue 7 is provided at the connection between the air outlet 6 and the housing 1. A second volute tongue 8 is provided at the end of the first volute tongue 7. The side of the second volute tongue 8 near the air outlet 6 is smoothly connected to the first volute tongue 7 to avoid sudden changes in airflow velocity at the air outlet 6 due to sudden changes in the cross-section of the air outlet 6. The second volute tongue 8 is inclined towards the side closer to the impeller to further reduce the gap between the volute tongue and the impeller, preventing the gas accelerated by the centrifugal force of the impeller from re-entering the housing 1 through the gap and affecting the operating efficiency of the fan.

[0047] The first volute tongue 7 and the second volute tongue 8 are welded to the shell 1 and then formed by grinding the weld points;

[0048] The first volute tongue 7 has a resonant cavity 11 inside. The cross-section of the resonant cavity 11 can be triangular, with one vertex of the triangle facing the second volute tongue 8. This is to better transmit the vibration generated by the volute tongue and thus achieve better vibration reduction. Inside the resonant cavity 11, a resonant plate 12 is installed along the radial direction of the shell 1 via a connector 13. When the gas accelerated by the centrifugal force of the impeller impacts the volute tongue, the resonant cavity 11 and the resonant plate 12 inside it vibrate, thereby canceling the overall vibration of the volute tongue and reducing the noise generated by the airflow impacting the volute tongue at the air outlet 6.

[0049] The resonant cavity 11 is in a vacuum state. By evacuating the resonant cavity 11, the propagation of sound generated by the vibration of the resonant plate 12 inside the resonant cavity 11 is blocked. The connector 13 is an elastic connector. For example, the resonant plate 12 is connected to the side wall of the resonant cavity 11 by an elastic rope. The purpose is also to reduce the propagation of sound generated by the vibration of the resonant plate 12, thereby achieving the effect of noise reduction.

[0050] The second volute tongue 8 is provided with several guide elements 9 at equal intervals on the side near the impeller, and a guide channel 10 is formed between two adjacent guide elements 9.

[0051] The width of the guide member 9 gradually increases along the gas flow direction, causing the guide channel 10 to gradually decrease along the gas flow direction. The purpose is to increase the gas velocity when a small amount of gas re-enters the housing 1 through the gap, thereby avoiding pressure exchange between the gas entering the housing 1 through the volute tongue and impeller and the accelerated gas inside the housing 1, which would otherwise form periodic pulses and achieve noise reduction.

[0052] In this embodiment, the impeller is driven to rotate by a motor. Outside air enters the fan housing 1 through the rectifier. The gas is accelerated by the centrifugal force generated during the rotation of the impeller and flows through the gap between the impeller and the housing 1 to the air outlet 6, and is discharged through the air outlet 6.

[0053] like Figures 7-8 As shown, the rectifier includes a first rectifier 501 and a second rectifier 502. The first rectifier 501 and the second rectifier 502 are coaxially mounted at the air inlet 4. The diameter of the second rectifier 502 is smaller than that of the first rectifier 501. The second rectifier 502 is located inside the first rectifier 501. Both the first rectifier 501 and the second rectifier 502 are streamlined designs to reduce the impact generated when the gas enters the housing 1. Inside the housing 1, a guide is coaxially mounted with the impeller, the air inlet 4 and the rectifier.

[0054] like Figure 9As shown, the gas entering the housing 1 through the gap between the first shroud 501 and the second shroud 502 diffuses to both sides of the impeller and is accelerated by the centrifugal force of the high-speed rotating impeller. The gas entering the housing 1 through the second shroud 502 is guided to the position of the guide element, eliminating the intake vortex generated by the gas entering the housing 1 through the air inlet 4, thereby reducing noise.

[0055] like Figures 10-11 As shown, the drainage component includes a drainage seat 1401, a drainage cavity 1402, a guide cone 1403, and a guide hole 1404;

[0056] The flow guide seat 1401 is installed inside the impeller to guide the airflow entering the housing 1 through the second rectifier 502, avoiding the generation of intake vortices and thus reducing noise. The flow guide seat 1401 has a flow guide cavity 1402 on the side facing the rectifier, allowing the airflow to enter the flow guide cavity 1402. A guide cone 1403 is installed inside the flow guide cavity 1402 to divert the airflow entering the flow guide cavity 1402. A guide hole 1404 is opened on the side wall of the flow guide seat 1401. The flow guide cavity 1402 and the guide cone 1403 are used to guide the airflow to the guide hole 1404, and guide the airflow to the impeller position through the guide hole 1404, thereby improving the operating efficiency of the fan.

[0057] The guide element rotates synchronously with the impeller, and the guide hole 1404 is bent along the impeller rotation direction. When the gas enters the guide chamber 1402, under the rotation of the guide seat 1401, the gas flows out through the guide hole 1404, so that the initial flow direction of the gas is the same as the impeller rotation direction, thereby improving the operating efficiency of the fan. Furthermore, since the guide hole 1404 is bent along the impeller rotation direction, pre-swirl intake is achieved, reducing the impact of airflow on the impeller and thus reducing noise.

[0058] In this embodiment, the gas entering the housing 1 through the second rectifier 502 enters the drainage cavity 1402 and is dispersed into the drainage hole 1404 under the action of the guide cone 1403. At the same time, the entire drainage seat 1401 rotates with the rotation of the impeller, causing the gas to flow out through the drainage hole 1404.

[0059] like Figures 12-13As shown, the impeller consists of a disk 201 and blades 202. The blades 202 are backward-curved blades, forming an arc-shaped convex surface 203 and an arc-shaped concave surface 204. A turning part 205 is provided at the trailing edge of the blades 202. A flow-guiding hole 206 is provided at the position of the turning part 205 and the arc-shaped convex surface 203, which penetrates the blades 202. Through the design of the flow-guiding hole 206, some gas can flow through the flow-guiding hole 206 when the blades 202 rotate, thereby realizing that there is also gas flow at the trailing edge of the arc-shaped concave surface 204. This reduces the possibility of Karman vortex street generated due to airflow boundary layer separation, thereby avoiding pressure fluctuations caused by alternating vortex shedding and reducing the possibility of noise generation.

[0060] The trailing edge refers to the portion located on the concave surface 204 near the guide.

[0061] The angle formed between the surface of the turning part 205 and the surface of the arc-shaped convex surface 203 is an obtuse angle, for example, the angle is 135°. Since the drainage hole 206 is installed at the position of the turning part 205 and the arc-shaped convex surface 203, the air flow rate through the drainage hole 206 can be further increased.

[0062] The central axis of the end of the guide hole 1404 is on the same axis as the central axis of the drain hole 206. When the gas flows out through the guide hole 1404, a part of the gas will directly reach the position of the arc concave surface 204 through the drain hole 206, thereby ensuring the amount of gas at the trailing edge of the arc concave surface 204 and avoiding the generation of Karman vortex street due to boundary layer separation. At the same time, it can also reduce the impact of airflow on the blade 202 and achieve noise reduction of the fan.

[0063] In this embodiment, the gas flowing out through the guide hole 1404 is accelerated by the blade 202. At the same time, part of the gas flowing out through the guide hole 1404 will flow through the guide hole 206, and part of the airflow through the arc-shaped convex surface 203 will also flow through the guide hole 206. Under this action, part of the airflow can flow through the trailing edge of the arc-shaped concave surface 204, which can avoid the generation of Karman vortex street due to boundary layer separation.

[0064] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A noise-reducing centrifugal fan structure, comprising a housing (1) and an impeller driven to rotate inside the housing (1) by a drive component (3), wherein the housing (1) is provided with an air inlet (4) and an air outlet (6) in the axial and radial directions, respectively, characterized in that: A rectifier for guiding the incoming gas is provided at the air inlet (4); A first volute tongue (7) is provided at the connection between the air outlet (6) and the housing (1). A second volute tongue (8) is provided at the end of the first volute tongue (7). The second volute tongue (8) is smoothly connected to the first volute tongue (7) on the side near the air outlet (6). The second volute tongue (8) is inclined towards the side near the impeller. A plurality of guide elements (9) are provided at equal intervals on the side of the second volute tongue (8) near the impeller. A guide channel (10) is formed between two adjacent guide elements (9). The width of the guide member (9) gradually increases along the gas flow direction, causing the guide channel (10) to gradually decrease along the gas flow direction; Inside the housing (1), a flow guide is coaxially mounted with the impeller, air inlet (4) and rectifier; The drainage component includes a drainage seat (1401), a drainage cavity (1402), a guide cone (1403), and a guide hole (1404). The flow guide seat (1401) is installed inside the impeller. The flow guide seat (1401) has a flow guide cavity (1402) on the side facing the rectifier. A flow guide cone (1403) is installed inside the flow guide cavity (1402). A flow guide hole (1404) is opened on the side wall of the flow guide seat (1401). The flow guide rotates synchronously with the impeller, and the flow guide hole (1404) is bent along the impeller rotation direction; The rectifier includes a first rectifier (501) and a second rectifier (502). The first rectifier (501) and the second rectifier (502) are coaxially mounted at the air inlet (4). The diameter of the second rectifier (502) is smaller than that of the first rectifier (501). The second rectifier (502) is located inside the first rectifier (501). The impeller is composed of a disc (201) and blades (202). The blades (202) are backward-curved blades, forming an arc-shaped convex surface (203) and an arc-shaped concave surface (204). A turning part (205) is provided at the trailing edge of the blade (202). A flow-guiding hole (206) penetrating the blade (202) is opened at the position of the turning part (205) and the arc-shaped convex surface (203). The central axis of the end of the guide hole (1404) is on the same axis as the central axis of the drain hole (206).

2. The structure of a noise-reducing centrifugal fan according to claim 1, characterized in that: The first volute tongue (7) has a resonant cavity (11) inside, and a resonant plate (12) is installed inside the resonant cavity (11) along the radial direction of the shell (1) via a connector (13).

3. The structure of a noise-reducing centrifugal fan according to claim 2, characterized in that: The resonant cavity (11) is in a vacuum state, and the connector (13) is an elastic connector.

4. The structure of a noise-reducing centrifugal fan according to claim 1, characterized in that: The angle formed between the surface of the turning part (205) and the surface of the arc-shaped convex surface (203) is an obtuse angle.

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