Low-turbulence noise reduction turbofan

Abstract

The low-turbulence noise reduction turbofan comprises a motor and an impeller fixedly installed at the output end of the motor, a motor shell is arranged outside the motor, a volute installed on the motor shell is arranged outside the impeller in a covering mode to form a volute flow channel, an air inlet right opposite to the impeller is formed in the top of the volute, and an air outlet is formed in the side edge of the volute. The inner wall of the volute is fixedly connected with a flow dividing device located below the impeller, the cross section of the flow dividing device is annular, the bottom of the flow dividing device is higher than the bottom of the air outlet, and flow dividing forked channels are formed between the inner ring and the inner wall of the volute on the two sides and between the outer ring and the inner wall of the volute on the two sides. And air flow at the outlet of the impeller is rectified by the flow dividing device, is spread downwards from the flow dividing forked channels on the two sides and is finally discharged from the air outlet. The volute flow channel is structurally optimized, and turbulent flow at the outlet of the impeller is rectified, so that turbulent flow in the volute is reduced, and then aerodynamic noise in the volute is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of turbo fans, and in particular to a low-turbulence noise-reducing turbo fan. Background Art

[0002] A ventilator is an extracorporeal respiratory gas source providing device for respiratory therapy or assisted ventilation. The turbine fan is one of the core components of the ventilator. The flow and pressure required by the ventilator come from the turbine fan. The pressure, flow and noise performance of the turbine fan are directly related to the performance of the ventilator. Medical emergency ventilators mainly focus on the maintenance and recovery functions of respiratory physiological special diagnosis, and have a relatively high tolerance for noise. Home ventilators are often used in non-emergency situations, such as the improvement of sleep apnea (commonly known as snoring). Users have a more stringent tolerance for noise and hope that the ventilator will not produce noise interference to ensure a quiet sleeping environment. The main source of noise from the turbine fan is aerodynamic noise. When the impeller rotates, the high-speed beating of the airflow and the wall and the turbulence formed by the airflow itself will generate noise. At this stage, noise reduction fan products mainly improve noise performance by optimizing the impeller shape. It is already difficult to improve noise reduction performance. Noise is not only related to the impeller, but also to the volute flow channel. However, there are few solutions to reduce noise by optimizing the volute flow channel structure, which is worth further study. Summary of the invention

[0003] The purpose of the present invention is to propose a low turbulence noise reduction turbine blower in view of the shortcomings of the prior art. By optimizing the structure of the volute flow channel, the turbulent airflow at the impeller outlet is rectified, thereby reducing the turbulence in the volute and further reducing the aerodynamic noise in the volute.

[0004] The technical solution to achieve the purpose of the present invention is:

[0005] A low-turbulence noise reduction turbine fan comprises a motor and an impeller fixedly mounted at the output end of the motor, wherein a motor housing is provided on the outside of the motor, and an outer cover of the impeller is provided with a volute mounted on the motor housing to form a volute flow channel, wherein an air inlet facing the impeller is provided on the top of the volute, and an air outlet is provided on the side, and a diverter device with a ring-shaped cross section and located below the impeller is fixedly connected to the inner wall of the volute, wherein the bottom of the diverter device is higher than the bottom of the air outlet, and a diverter fork is formed between the inner ring and the outer ring and the inner walls of the volute on both sides, respectively, and the airflow at the outlet of the impeller is rectified by the diverter device, propagates downward from the diverter fork on both sides and is finally discharged from the air outlet.

[0006] Furthermore, the longitudinal cross-section of the diversion device is spindle-shaped, with a larger upper portion and a smaller lower portion, a flat top, and a sharp bottom.

[0007] Furthermore, the longitudinal cross-section of the diversion device includes a first arc located at the top, and a second arc and a third arc are symmetrically arranged at both ends of the first arc, which are connected in sequence, and the two third arcs converge to the same point. The curvature radii of the first arc, the second arc and the third arc are 2 mm, 17.5 mm, and 8.5 mm, respectively.

[0008] Furthermore, the inner ring or the outer ring of the flow dividing device is provided with a connecting column integrally formed with the inner wall of the adjacent volute, and the outer shape of the connecting column is streamlined.

[0009] Furthermore, annular baffles are symmetrically arranged above the diverter device and are integrally formed with the inner walls of the volute on both sides. A confluence channel with an annular structure is formed between the two annular baffles. The confluence channel is located directly above the diverter device and has a minimum cross-sectional area larger than the effective area of ​​the impeller outlet.

[0010] Furthermore, a projected area of ​​the diverter device on a horizontal plane is larger than a cross-sectional area of ​​the confluence channel.

[0011] Furthermore, the flow dividing device is arranged centrally in the volute flow channel along the horizontal direction.

[0012] Furthermore, the upper part of the volute flow channel is provided with a rectifying channel extending outward and having a streamlined longitudinal cross-section, the upper end of the rectifying channel is connected to the impeller outlet, the lower end is connected to the converging channel, and the minimum area of ​​the cross-section is larger than the effective area of ​​the impeller outlet.

[0013] Furthermore, the minimum cross-sectional area of ​​the rectifying channel is less than or equal to 1.5 times the effective area of ​​the impeller outlet.

[0014] Furthermore, the volute is composed of an upper volute and a lower volute that are engaged with each other, the impeller includes a lower cover plate and a blade assembly arranged on the lower cover plate, the upper part of the inner wall of the upper volute is an outwardly expanding inclined arc surface and transitions with the top arc of the upper volute, the lower volute is clamped on the motor housing, and an annular cone is provided on the top, and the rectification channel is formed between the outer wall of the annular cone and the inclined arc surface.

[0015] Furthermore, the top of the annular frustum extends to the lower cover plate, is located between the bottom and the top of the lower cover plate, and the gap d between the lower cover plate satisfies 0.4mm≤d≤1mm.

[0016] Furthermore, the impeller is a coverless impeller, and the blade assembly adopts a diversion structure design, including main blades evenly arranged along the circumference and diversion blades arranged between adjacent main blades. The main blades and the diversion blades are both arc-shaped structures, ensuring low inertia of the impeller, thereby achieving high dynamic characteristics.

[0017] Furthermore, the top profile of the inner wall of the upper volute has the same curvature radius as the outer profile of the impeller, the outer diameter of the formed profile is D1, the lower end diameter of the inclined arc surface is D2, the height is H, and 2H / (D2-D1)>1.73 is satisfied. By optimizing the profile of the inner wall of the upper volute and strictly controlling its size, the impeller outlet noise is reduced while the impeller outlet flow is not affected, thereby meeting the requirements of high response and low noise.

[0018] Furthermore, the gap between the top profile of the impeller and the top surface of the inner wall of the upper volute is 0.5 to 1 mm.

[0019] Furthermore, the intersection lines in the volute flow channel are all chamfered to reduce impact and flow resistance, thereby increasing flow and achieving better noise reduction.

[0020] Furthermore, an annular protrusion located on the inner wall of the upper volute and extending downward is provided at the air inlet, and the cross-section of the annular protrusion is in the shape of a barb, which prevents the backflow turbulence between the top of the impeller and the wall of the upper volute from entering the volute inlet, thereby reducing the inlet noise.

[0021] By adopting the above technical solution, the present invention has the following beneficial effects:

[0022] (1) The present invention provides a flow diversion device to form two flow diversion forks at the lower part of the volute flow channel, so that the airflow at the impeller outlet is dispersed into the two flow diversion forks and then discharged from the air outlet, thereby rectifying the turbulent airflow at the impeller outlet, thereby reducing the turbulence in the volute, and further reducing the aerodynamic noise in the volute.

[0023] (2) The flow diversion device of the present invention adopts an annular structure with a spindle-shaped longitudinal cross-section, with a relatively flat top and a relatively sharp bottom, so that the airflow can only flow from top to bottom. Even if there is a small amount of airflow from bottom to top, when the airflow flows out from the top of the flow diversion device, the speed direction is exactly opposite to the fluid from top to bottom. After the kinetic energy is offset, it cannot continue to flow back. Therefore, there is only airflow from top to bottom in the volute, and after being diverted by the flow diversion device, it enters the flow channels on both sides to produce a rectifying effect again, thereby reducing the aerodynamic noise in the volute.

[0024] (3) The present invention fixes the diversion device through an integrally formed connecting column, which has a simple structure, a firm connection, and avoids shaking. At the same time, the connecting column is also set to be streamlined to further reduce the flow resistance and ensure that the flow size meets the requirements.

[0025] (4) The present invention forms a converging channel located directly above the diverter device through two annular baffles, so that the airflow at the impeller outlet can be converged into the annular flow channel, and then diverted by the diverter device below, thereby improving the rectification effect.

[0026] (5) The present invention sets the maximum cross-sectional area of ​​the diversion channel so that the projection of the diversion device and the annular baffle on the horizontal plane blocks the path for the airflow noise to propagate downward, thereby further reducing the propagation of noise.

[0027] (6) The flow diversion device of the present invention is arranged in the center of the volute flow channel along the horizontal direction, so that the flow areas of the diversion forks on both sides are the same, and the flow can be evenly diverted to achieve a better noise reduction effect.

[0028] (7) The present invention adds a rectifying channel with a special structure in the volute flow channel, so that the airflow passes through a streamlined structure transition after flowing out from the impeller outlet, thereby achieving rectification and reducing turbulent noise. By controlling the minimum flow area of ​​the rectifying channel to be larger than the effective area of ​​the impeller outlet, the impeller outlet flow rate is ensured to be unaffected.

[0029] (8) The present invention controls the minimum flow area of ​​the rectifying channel to be no greater than 1.5 times the effective area of ​​the impeller outlet. If the area is too large, the air flow beam will diverge after flowing out of the impeller outlet, thereby increasing the turbulent noise.

[0030] (9) The present invention forms a rectifying channel by means of the inclined arc surface of the inner wall of the upper volute and the annular frustum at the top of the lower volute. Only the volute structure needs to be improved. The structure is simple and has universal applicability.

[0031] (10) The present invention prevents the impeller outlet from rubbing against the impeller outlet by strictly controlling the lateral clearance between the annular cone and the impeller. It also reduces the influence of the cavity airflow at the bottom of the impeller lower cover plate on the airflow in the volute flow channel, thereby reducing the cavity airflow noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 It is a structural schematic diagram of the present invention;

[0034] Figure 2 It is a schematic diagram of the explosion structure of the present invention;

[0035] Figure 3 It is a structural schematic diagram of the lower volute of the present invention;

[0036] Figure 4 It is a schematic diagram of the internal structure of the present invention.

[0037] The reference numerals in the accompanying drawings are:

[0038] Impeller 1, lower cover plate 1-1, main blade 1-2, splitter blade 1-3, motor housing 2, volute 3, upper volute 3-1, lower volute 3-2, annular frustum 3-3, splitter device 4, connecting column 4-1, air inlet 5, air outlet 6, annular baffle 7, annular convex portion 8 DETAILED DESCRIPTION

[0039] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0040] (Example 1)

[0041] like Figures 1 to 4 The low turbulence noise reduction turbine fan shown includes a motor, an impeller 1, a motor housing 2, a volute 3 and a flow divider 4. The motor is fixed in the motor housing 2, and the output end extends to the outside and is coaxially fixedly connected to the impeller 1. The volute 3 is covered on the outside of the impeller 1 to form a volute flow channel. The top of the volute 3 is provided with an air inlet 5 facing the rotation axis of the impeller 1, and the side is provided with an air outlet 6. The cross section of the flow divider 4 is annular, coaxially arranged below the impeller 1 and fixedly connected to the inner wall of the volute 3, and the bottom is higher than the bottom of the air outlet 6. The inner ring and the outer ring form a flow divider fork between the inner wall of the volute on both sides, so that the airflow at the outlet of the impeller 1 is rectified by the flow divider 4 and propagates downward from the flow divider fork on both sides and is finally discharged from the air outlet, thereby rectifying the turbulent airflow at the outlet of the impeller, reducing the turbulence in the volute, and further reducing the aerodynamic noise in the volute.

[0042] Specifically, the impeller 1 is a coverless impeller, including a lower cover plate 1-1 and a blade assembly arranged on the lower cover plate 1-1, wherein the blade assembly adopts a diversion structure design, including main blades 1-2 evenly arranged along the circumferential direction and diversion blades 1-3 arranged between adjacent main blades 1-2, and the main blades 1-2 and the diversion blades 1-3 are both arc-shaped structures, ensuring low inertia of the impeller, thereby achieving high dynamic characteristics.

[0043] The volute 3 is composed of an upper volute 3-1 and a lower volute 3-2 that are engaged with each other. The upper part of the inner side wall of the upper volute 3-1 is an outwardly expanding oblique arc surface that transitions with the inner top surface of the upper volute 3-1. The lower volute 3-2 is mounted on the motor housing 2, and an annular cone 3-3 is provided on the top. A rectifying channel is formed between the outer wall of the annular cone 3-3 and the oblique arc surface. An annular baffle 7 that is integrally formed with the inner wall of the volute on both sides is symmetrically provided above the flow dividing device 4, and a converging channel of an annular structure is formed between the two annular baffles 7.

[0044] The longitudinal cross section of the rectifying channel is streamlined, the upper end is connected to the impeller outlet, the lower end is connected to the converging channel, and the minimum cross-sectional area is larger than the effective area of ​​the impeller outlet and less than or equal to 1.5 times the effective area of ​​the impeller outlet, ensuring that the impeller outlet flow is not affected. The converging channel is located directly above the diverter 4 and the minimum cross-sectional area is larger than the effective area of ​​the impeller outlet.

[0045] The diverter is arranged in the center of the volute flow channel along the horizontal direction, so that the flow areas of the diverter forks on both sides are the same, and the diverter can be equally divided to achieve a better noise reduction effect. The longitudinal section of the diverter is a spindle-shaped device that is larger at the top and smaller at the bottom, with a flat top and a sharp bottom. It includes a first arc at the top to form a flat top, and the two ends of the first arc are symmetrically provided with a second arc and a third arc connected in sequence. The two third arcs converge to the same point to form a sharp bottom. The curvature radii of the first arc, the second arc and the third arc are 2mm, 17.5mm, and 8.5mm respectively.

[0046] The turbulent airflow at the outlet of the impeller 1 is first rectified through the rectifying channel, and then flows to the diversion fork below through the converging channel. The diverting device adopts an annular structure with a spindle-shaped longitudinal cross-section, with a relatively flat top and a relatively sharp bottom, so that the airflow can only flow from top to bottom. Even if there is a small amount of airflow from bottom to top, when the airflow flows out from the top of the diverting device 4, the speed direction is just opposite to the fluid from top to bottom. After the kinetic energy is offset, it cannot continue to flow back. Therefore, there is only airflow from top to bottom in the volute, and after being diverted by the diverting device 4, it enters the flow channels on both sides to produce a rectifying effect again, thereby reducing the aerodynamic noise in the volute. The minimum cross-sectional area of ​​the converging channel is smaller than the projection area of ​​the diverting device on the horizontal plane, so that the projection of the diverting device 4 and the annular baffle 7 on the horizontal plane blocks the path for the airflow noise to propagate downward, further reducing the propagation of noise.

[0047] The top of the annular cone 3-3 extends to the lower cover plate 1-1, and is located between the bottom and the top of the lower cover plate 1-1, and the gap d between the lower cover plate 1-1 satisfies 0.4mm≤d≤1mm, achieving an appropriate small gap to prevent the impeller outlet from scratching it, and at the same time also reduces the impact of the cavity airflow at the bottom of the impeller lower cover plate on the airflow in the volute flow channel, thereby reducing the cavity airflow noise.

[0048] The inner ring or outer ring of the diverter device 4 is provided with a connecting column 4-1 integrally formed with the inner wall of the adjacent volute. The connecting column 4-1 of this embodiment is located in the inner ring of the diverter device 4, and two are symmetrically provided to achieve the fixation of the diverter device. The structure is simple, the connection is firm, and shaking is avoided. The shape of the connecting column 4-1 is streamlined, which further reduces the flow resistance and ensures that the flow rate meets the requirements.

[0049] The top profile of the inner wall of the upper volute 3-1 has the same radius of curvature as the outer profile of the impeller 1. The outer diameter of the formed profile is D1, which is the same as the outer diameter of the impeller 1, ensuring that the flow of the blade tip gap remains stable at the impeller outlet. The lower end diameter of the inclined arc surface is D2, the height is H, and 2H / (D2-D1)>1.73 is satisfied. By optimizing the inner wall profile of the upper volute and strictly controlling its size, the impeller outlet noise is reduced while ensuring that the impeller outlet flow is not affected, thereby meeting the requirements of high response and low noise. The gap between the top profile of the impeller 1 and the top surface of the inner wall of the upper volute is 0.5 to 1 mm, which can ensure that the impeller and the volute do not scrape and maintain a low level of noise. In order to further reduce the impact and flow resistance, the intersection lines in the volute flow channel of this embodiment are all chamfered, which has a better noise reduction effect while increasing the airflow rate.

[0050] In addition, this embodiment provides an annular protrusion 8 located on the inner wall of the upper volute 3-1 and extending downward at the air inlet 5. The cross-section of the annular protrusion 8 is in the shape of a barb, which prevents the backflow turbulence between the top of the impeller and the wall of the upper volute from entering the volute inlet, thereby reducing the inlet noise.

[0051] The noise of multiple turbine fan samples was tested, among which samples 1 to 3 adopted the structure of this embodiment, and samples 4 to 5 were similar to the structure of embodiment 1, except that the top slope size parameters of the upper volute did not meet the standards. The relevant sample parameters and test results are shown in the following table:

[0052]

[0053] (Comparative Example 1)

[0054] The structure of comparative example 1 is similar to that of embodiment 1, except that there is no diverter device 4 .

[0055] (Comparative Example 2)

[0056] The structure of comparative example 2 is similar to that of embodiment 1, except that there is no annular baffle 7.

[0057] (Comparative Example 3)

[0058] The structure of comparative example 3 is similar to that of embodiment 1, except that there is no rectifying channel.

[0059] The samples of Comparative Examples 1 to 3 were tested for performance, and the results are shown in the following table:

[0060] Noise test results / dB(A) Flow rate at air outlet / lpm Comparative Example 1 43.2 418 Comparative Example 2 44.7 425 Comparative Example 3 45.6 432

[0061] The present invention provides a rectifying channel, a converging channel and a diverting device, so that when the airflow flows out from the impeller outlet, it is rectified, converged and then diverted in sequence, and the turbulent airflow at the impeller outlet is rectified, thereby reducing the turbulence in the volute and further reducing the aerodynamic noise in the volute; at the same time, by strictly controlling the size of the upper part of the volute flow channel, the outlet flow rate is maintained above 380 / lpm and the noise is controlled within 41 / dB(A), with excellent performance.

[0062] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low turbulence noise reduction turbine fan, comprising a motor and an impeller fixedly mounted at the output end of the motor, wherein the motor is provided with a motor housing on the outside, and the outer cover of the impeller is provided with a volute mounted on the motor housing to form a volute flow channel, and the top of the volute is provided with an air inlet facing the impeller, and the side is provided with an air outlet, characterized in that: The inner wall of the volute is fixedly connected with a diverter device with a ring-shaped cross section and located below the impeller. The bottom of the diverter device is higher than the bottom of the air outlet. The inner ring and the outer ring form diverter channels with the inner walls of the volute on both sides respectively. The airflow at the outlet of the impeller is rectified by the diverter device, propagates downward from the diverter channels on both sides and is finally discharged from the air outlet.

2. A low turbulence noise reduction turbo blower according to claim 1, characterized in that: The longitudinal cross-section of the diversion device is in the shape of a spindle, which is larger at the top and smaller at the bottom, with a flat top and a sharp bottom.

3. A low turbulence noise reduction turbo blower according to claim 2, characterized in that: The inner ring or the outer ring of the flow dividing device is provided with a connecting column integrally formed with the inner wall of the adjacent volute, and the outer shape of the connecting column is streamlined.

4. The low turbulence noise reduction turbo blower according to claim 2, characterized in that: Annular baffles are symmetrically arranged above the diverter device and are integrally formed with the inner walls of the volute on both sides. A confluence channel with an annular structure is formed between the two annular baffles. The confluence channel is located directly above the diverter device and has a minimum cross-sectional area larger than the effective area of ​​the impeller outlet.

5. A low turbulence noise reduction turbo blower according to claim 4, characterized in that: The projected area of ​​the diverter device on the horizontal plane is larger than the cross-sectional area of ​​the converging channel.

6. The low turbulence noise reduction turbo blower according to claim 1, characterized in that: The flow dividing device is centrally arranged in the volute flow passage along the horizontal direction.

7. The low turbulence noise reduction turbo blower according to claim 4, characterized in that: The upper part of the volute flow channel is provided with a rectifying channel extending outward and having a streamlined longitudinal cross section. The upper end of the rectifying channel is connected to the impeller outlet, the lower end is connected to the converging channel, and the minimum area of ​​the cross section is larger than the effective area of ​​the impeller outlet.

8. The low turbulence noise reduction turbo blower according to claim 7, characterized in that: The minimum cross-sectional area of ​​the rectifying channel is less than or equal to 1.5 times the effective area of ​​the impeller outlet.

9. The low turbulence noise reduction turbo blower according to claim 7, characterized in that: The volute is composed of an upper volute and a lower volute that are engaged with each other, the impeller includes a lower cover plate and a blade assembly arranged on the lower cover plate, the upper part of the inner side wall of the upper volute is an outwardly expanding inclined arc surface and transitions with the top arc of the upper volute, the lower volute is clamped on the motor housing, and an annular frustum is provided on the top, and the rectification channel is formed between the outer wall of the annular frustum and the inclined arc surface.

10. The low turbulence noise reduction turbo blower according to claim 9, characterized in that: The top of the annular frustum extends to the lower cover plate, and a gap d between the top and the lower cover plate satisfies 0.4 mm ≤ d ≤ 1 mm.

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