Double-impeller centrifugal fan with noise reduction type centrifugal impeller

Abstract

The invention discloses a double-impeller centrifugal fan with noise reduction type centrifugal impellers, which belongs to the technical field of cooling fans and comprises a frame, a motor and impellers. An air inlet duct is arranged at the end of the rack, and an air outlet duct is arranged on the side wall of the rack. The impeller comprises a rear wheel disc, a front wheel disc and a plurality of blades, the blades are clamped between the rear wheel disc and the front wheel disc in an arc-shaped plate shape, the blades are rotationally and symmetrically arranged on the radial plane of the impeller in the circumferential direction, and an air inlet of the front wheel disc is opposite to the air inlet channel. The cutting angles of the air outlet ends and the air inlet ends of the blades are controlled within a certain angle range, and the noise influence is reduced while it is ensured that the blades have high air exhaust efficiency. The beveling design of the air outlet cutting edge and the air inlet cutting edge of the blade can improve the phenomenon of non-uniform airflow at the turning position, so that the circumferential speed of the airflow on different sections of the blade is changed, and the airflow at the front edge of the blade enters an impeller runner without impact as much as possible.

Description

Technical Field

[0001] The invention belongs to the technical field of heat dissipation fans, and in particular is a double-impeller centrifugal fan with a noise-reducing centrifugal impeller. Background Art

[0002] With the rapid development of rail transit technology, subways, urban rails, high-speed trains and other vehicles are gradually evolving towards high speed, high efficiency and environmental protection. During the operation of the train, the traction motor provides the train with forward power, and the traction inverter controls the starting, braking and speed regulation of the traction motor. Especially when the train speed increases, the heat generated by the traction motor and inverter during operation increases significantly. If the heat cannot be dissipated in a timely and effective manner, it will directly affect the operating stability and service life of the equipment.

[0003] At present, centrifugal fans are widely used to provide cooling air for traction converters and traction motors. They deliver a large amount of cold air into the converter cabinet through high-speed rotation, forcing cooling and ventilation of internal heat-generating components, quickly taking away the generated heat and discharging it into the atmosphere to maintain the normal operating temperature of the equipment.

[0004] However, traditional centrifugal fans generate significant aerodynamic noise and mechanical noise when running at high speeds, and are not good at noise control. These noises not only have an adverse impact on the comfort of the train's internal environment, but may also cause noise pollution to the train's external environment, making it difficult to meet the increasingly stringent sound quality requirements of rail transit vehicles. Summary of the invention

[0005] The object of the present invention is to provide a double-impeller centrifugal fan with a noise-reducing centrifugal impeller to solve the problems raised in the above-mentioned prior art.

[0006] Provided is a double-impeller centrifugal fan with a noise-reducing centrifugal impeller, comprising:

[0007] A frame, wherein an air inlet is disposed at an end of the frame, and an air outlet is disposed on a side wall of the frame opposite to the air inlet;

[0008] A motor, wherein the motor is arranged inside the frame;

[0009] An impeller, comprising a rear wheel disc, a front wheel disc and a plurality of blades, wherein the rear wheel disc is fixedly connected to the output shaft of the motor, the plurality of blades are each in an arc-shaped plate shape and clamped between the rear wheel disc and the front wheel disc, the plurality of blades are arranged symmetrically in the circumferential direction on the radial plane of the impeller, and the air inlet of the front wheel disc is arranged opposite to the air inlet duct;

[0010] The blades respectively form an outlet end located on the outer circle of the blade rotation path ring and an inlet end located on the inner circle of the blade rotation path ring on the radial plane of the impeller, wherein an angle of β1 degrees is formed between a tangent line on the outer circle of the rotation path ring of the outlet end and an extension line of the outlet end, and 30°≤β1≤60°, and an angle of β2 degrees is formed between a tangent line on the inner circle of the rotation path ring of the inlet end and an extension line of the inlet end, and 15°≤β2≤35°;

[0011] The side of the blade located at the air outlet end is the air outlet cutting edge, and the side of the blade located at the air inlet end is the air inlet cutting edge. The extended line of the air outlet cutting edge forms an angle of α1 degrees with the central axis of the impeller, and 0<α1≤9°. The extended line of the air inlet cutting edge forms an angle of α2 degrees with the central axis of the impeller, and 0<α2≤9°.

[0012] As a further solution of the present invention: an angle of β1 degrees is formed between the tangent line of the air outlet on the outer circle of the rotating path ring and the extension line of the air outlet, and 32°≤β1≤36°; an angle of β2 degrees is formed between the tangent line of the air inlet on the inner circle of the rotating path ring and the extension line of the air inlet, and 19°≤β2≤23°.

[0013] As a further solution of the present invention: the line between the two end points of the wind inlet cut edge is the extension line of the wind inlet cut edge, and the wind inlet cut edge forms a continuously fluctuating concave-convex structure relative to the extension line. In order to reduce the airflow impact vortex at the leading edge of the blade and reduce the vortex noise at the impeller inlet, the wind inlet cut edge of the blade can be designed as an irregular concave-convex curve structure.

[0014] As a further solution of the present invention: the line connecting the two end points of the outlet trim is the extension line of the outlet trim, and the outlet trim forms a continuously fluctuating concave-convex structure relative to the extension line. Similar to the structure of the inlet trim, the outlet trim of the blade can be designed as an irregular concave-convex curve structure to break up the shedding vortex of the fluid-solid separation at the trailing edge of the blade and reduce the vortex noise at the impeller outlet

[0015] As a further solution of the present invention: the plane rotating around the central axis of the impeller is taken as the tangent plane, the part where the tangent plane intersects with the blade is the projection plane of the blade, and the extension line of the projection plane forms an angle of γ with the central axis of the impeller, and 0°<γ≤20°. The airflow inside the impeller is characterized in that the speed near the front wheel disc is greater than the speed of the rear wheel disc. At this time, the axial angle between the blade and the rear wheel disc can be tilted by a certain angle γ, so that the flow area is larger as it is closer to the front wheel disc, reducing the airflow speed and reducing the vortex loss caused by airflow separation.

[0016] As a further solution of the present invention: the air inlet forms a cylindrical air duct structure along the air flow direction, which first contracts inwards and then expands outwards. The air inlet forms a constriction structure in the middle area, and the air flow will first accelerate and then decelerate when flowing in it. The guided air flow enters the impeller very smoothly, and the inlet impact and vortex can be minimized, reducing the inlet vortex noise.

[0017] As a further solution of the present invention: the air inlet end of the air inlet duct is in the shape of a cone that gradually shrinks along the airflow direction, and the shrinkage angle of the cone is φ and 40°≤φ≤60°.

[0018] As a further solution of the present invention: the outlet end of the air inlet duct is sleeved in the front wheel disc, the overlap degree of the air inlet duct and the front wheel disc in the axial direction of the impeller center axis is h=2mm~6mm, and the clearance between the air inlet duct and the front wheel disc in the radial direction of the impeller center axis is δ=(0.5%~1%)D m , where D m The inner diameter of the front impeller on the radial plane. This design is used to reduce the air leakage loss and the vortex generated by leakage, so as to ensure the low noise of the impeller.

[0019] As a further solution of the present invention: an air inlet is respectively arranged at both ends of the frame, the motor has two output shafts, the number of the impellers is two, the two impellers are respectively fixedly connected to the two output shafts of the motor, and the two impellers are respectively arranged opposite to the two air inlets.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The impeller is a backward centrifugal impeller structure. The airflow enters from the air inlet duct on the impeller axis through the drive of the blades and is discharged from the radial direction of the impeller. The air extraction efficiency is mainly controlled by the cutting angle of the air outlet and air inlet ends of the blades. The present invention controls the cutting angle of the air outlet and air inlet ends of the blades within a certain angle range, ensuring that the blades have a greater air extraction efficiency while reducing the impact of noise. The bevel design of the air outlet cutting edge and the air inlet cutting edge of the blade can improve the uneven airflow at the corners without changing the cutting angle of the air outlet and air inlet ends of the blades, thereby changing the circumferential velocity of the airflow in different sections of the blades, so that the airflow at the leading edge of the blades enters the impeller flow channel as impact-free as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 It is an exploded view of the overall structure of a double-impeller centrifugal fan with a noise-reducing centrifugal impeller;

[0024] Figure 2 It is the cross-sectional structural arrangement diagram of the blades on the impeller radial plane;

[0025] Figure 3 is a schematic diagram of the structure of the impeller;

[0026] Figure 4 is a schematic diagram of the structure of the blade;

[0027] Figure 5 The following are examples of the cutting edge of the blade under different concave-convex structural states;

[0028] Figure 6 Schematic diagram of the bevel cutting structure of the blade;

[0029] Figure 7 Schematic diagram of the dumping structure of the blade;

[0030] Figure 8 It is a schematic diagram of the assembly state of the air inlet duct and the impeller;

[0031] Fig. 9 for Figure 8 Magnified view of area A.

[0032] In the figure: 1, frame; 11, air inlet; 12, air outlet; 2, motor; 3, impeller; 31, rear wheel disc; 32, front wheel disc; 33, blades; 331, air outlet end; 332, air inlet end; 333, air outlet trim; 334, air inlet trim. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0034] Obviously, the drawings described below are only some examples or embodiments of the present invention. For ordinary technicians in this field, the present invention can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed by the present invention, some changes in design, manufacturing or production based on the technical content disclosed by the present invention are just conventional technical means, and should not be understood as insufficient content disclosed by the present invention.

[0035] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present invention and are not intended to limit the subject matter described in the claims.

[0036] See also Figure 1 As shown, in an embodiment of the present invention, a double-impeller centrifugal fan with a noise-reducing centrifugal impeller includes a frame 1, a motor 2 and an impeller 3. An air inlet 11 is provided at the end of the frame 1, and an air outlet 12 is provided on the side wall of the frame 1 on the side different from the air inlet 11. The motor 2 is arranged inside the frame 1. The impeller 3 includes a rear wheel disc 31, a front wheel disc 32 and a plurality of blades 33, the rear wheel disc 31 is fixedly connected to the output shaft of the motor 2, and the plurality of blades 33 are each in the shape of an arc plate and clamped between the rear wheel disc 31 and the front wheel disc 32, and the plurality of blades 33 are arranged symmetrically in the circumferential direction on the radial plane of the impeller 3, and the air inlet of the front wheel disc 32 is arranged opposite to the air inlet 11.

[0037] The frame 1 is a closed structure except for the air inlet 11 and the air outlet 12. The motor 2 is installed inside the frame 1 to drive the impeller 3 to rotate inside the frame 1. When the impeller 3 rotates, the airflow enters the axial cavity area of ​​the impeller 3 from the air inlet 11, and is guided to the side of the impeller 3 through a plurality of blades 33 in the circumferential direction, and finally outputs the airflow from the air outlet 12.

[0038] See also Figure 1-Figure 3As shown, the blade 33 forms an air outlet end 331 located on the outer circle of the rotation path ring of the blade 33 and an air inlet end 332 located on the inner circle of the rotation path ring of the blade 33 on the radial plane of the impeller 3. When the impeller 3 guides the airflow, the airflow first contacts the air inlet end 332 after entering from the air inlet 11, then flows along the direction of the blade 33 and finally contacts the air outlet end 331. It should be noted here that the air outlet end 331 and the air inlet end 332 of the blade 33 are obtained by a certain cross section intercepted on the blade 33 by a certain radial plane of the impeller 3. The cross section can be any plane intercepted on the blade 33. Therefore, the air outlet end 331 and the air inlet end 332 on the blade 33 do not only refer to a single endpoint, but are a collection of endpoints intercepted by various radial planes.

[0039] The tangent line of the air outlet end 331 on the outer circle of the rotating path ring and the extension line of the air outlet end 331 form an angle of β1 degrees and 30°≤β1≤60°, and the tangent line of the air inlet end 332 on the inner circle of the rotating path ring and the extension line of the air inlet end 332 form an angle of β2 degrees and 15°≤β2≤35°. This angle range is used to form a pressure difference at both ends through the inclined structure of the arc plate when the blade 33 rotates, to form a certain wind pressure output of the airflow, and to improve the vortex structure to achieve noise reduction effect. Among them, β1 is preferably 32°~36°, and β2 is preferably 19°~23°, so as to achieve a greater exhaust efficiency and make the noise lower than the specification requirements.

[0040] See also Figure 1-Figure 4 As shown, the side of the blade 33 located at the air outlet end 331 is the air outlet trimming edge 333, and the side of the blade 33 located at the air inlet end 332 is the air inlet trimming edge 334. The air outlet trimming edge 333 is a set formed by each air outlet end 331 intercepted on the blade 33 by each radial plane of the impeller 3, indicating the extension track of the blade 33 on the side of the air outlet end 331. Similarly, the air inlet trimming edge 334 is a set formed by each air inlet end 332 intercepted on the blade 33 by each radial plane of the impeller 3, indicating the extension track of the blade 33 on the side of the air inlet end 332.

[0041] The line between the two end points of the outlet trim 333 is the extension line of the outlet trim 333, and the extension line of the outlet trim 333 forms an angle of α1 degrees with the central axis of the impeller 3, and 0<α1≤9°. The line between the two end points of the inlet trim 334 is the extension line of the inlet trim 334, and the extension line of the inlet trim 334 forms an angle of α2 degrees with the central axis of the impeller 3, and 0<α2≤9°. The inlet trim 334 of the blade 33 forms a beveled structure to improve the uneven airflow at the bend.

[0042] See also Figure 6As shown, the beveled edge 334 of the blade 33 means that the central cavity of the impeller 3 (excluding the rotation path of the blade 33) is close to the front wheel disc 32 at a diameter D 1max Greater than the diameter D of the rear wheel disc 31 1min , thereby changing the circumferential speed of the airflow in different radial sections at the central cavity, so that the airflow at the leading edge of the blade 33 enters the blade channel as non-impacting as possible. The bevel cutting of the air outlet cutting edge 333 of the blade 33 means that the outer circle of the rotation path of the blade 33 is close to the diameter D of the front wheel disc 32 2max Smaller than the diameter D of the rear wheel disc at 31 2min .

[0043] See also Figure 1 , Figure 4 and Figure 5 As shown, in order to reduce the impact vortex of the leading edge airflow and reduce the vortex noise at the air inlet of the impeller 3, the relative extension line of the air inlet trim 334 forms a continuously fluctuating concave-convex structure. The concave-convex structure can be designed as an irregular concave-convex curve structure, or a triangular or rectangular sawtooth structure, which is not specifically limited here, so as to break up the shed vortex of the fluid-solid separation at the leading edge of the blade 33 and reduce the vortex noise at the inlet of the impeller 3. Similarly, when the vortex is less, the air outlet trim 333 can also be designed as this concave-convex structure, and the specific structure will not be repeated in detail, so as to break up the shed vortex of the fluid-solid separation at the trailing edge of the blade 33 and reduce the vortex noise at the outlet of the impeller 3. Furthermore, the changing trends of the concave-convex structures of the curves of adjacent blades 33 can also be opposite, so as to form a reverse pulse excitation, disperse the concentrated frequency band noise, and reduce the rotational noise.

[0044] See also Figure 7 As shown, the plane rotating around the central axis of the impeller 3 is the section, and the part where the section intersects with the blade 33 is the projection surface of the blade 33. The extension line of the projection surface forms an angle of γ with the central axis of the impeller 3, and 0°<γ≤20°. The airflow inside the impeller 3 is characterized by a speed near the front wheel disc 32 that is greater than the speed of the rear wheel disc 31. At this time, the axial angle between the blade 33 and the rear wheel disc 31 can be 0° (i.e., perpendicular to the rear wheel disc 31), or it can be tilted at a certain angle γ, so that the flow area is larger in the area closer to the front wheel disc 32, reducing the airflow speed and reducing the vortex loss caused by airflow separation.

[0045] The number of blades 33 is n (9 in the embodiment of the present invention), and the blades 33 are rotationally symmetrical and evenly distributed along the circumferential direction, forming n air flow areas, and the flow area gradually increases from the inlet to the outlet, and the high-speed flow and rotating airflow are fully expanded, ensuring a sufficiently large flow and pressure of the fan. At the same time, the n blades 33 are not limited to being evenly distributed between the impellers 3, and can also be distributed at unequal intervals while taking into account the dynamic unbalance, so that the blades 33 do not hit the air in the same frequency band to form concentrated noise, thereby reducing the rotation noise of the fan.

[0046] See also Figure 8 and Fig. 9 As shown, the air inlet 11 is an axial air intake device that can smoothly guide the airflow to the impeller 3. The traditional air inlet 11 is arc-shaped, and the end of the air inlet 11 is vertically inserted into the front wheel disc 32. The airflow channel gradually shrinks from the outside to the inside, and there is no expansion process. The design of the air inlet 11 of the present invention takes into account its own flow loss and the flow condition of the outlet airflow when entering the impeller 3. The air inlet 11 is designed as a conical arc structure, that is, the air inlet end gradually shrinks into a conical cylinder, and the air outlet end 331 gradually becomes a radially expanding arc, and the arc is consistent with the line of the front wheel disc 32, so that an arc shape is formed with the outer end expanding, the middle end shrinking, and the end expanding again. The airflow flowing in it will produce a process of first accelerating and then decelerating. The guided airflow enters the impeller 3 very smoothly, and can minimize the inlet impact and vortex, reducing the inlet vortex noise.

[0047] After the fixed air inlet 11 and the rotating impeller 3 are assembled, a radial gap δ and an axial overlap h will be formed between the two. The gap δ between the air inlet 11 and the front wheel disc 32 in the radial direction of the central axis of the impeller 3 is (0.5% to 1%) D m , where D m is the inner diameter of the front wheel disc 32 on the radial plane. The overlap degree of the air inlet 11 and the front wheel disc 32 in the axial direction of the central axis of the impeller 3 is h=2mm~6mm. The radial clearance δ and the axial overlap h are used to ensure that the impeller 3 does not collide and interfere with the front wheel disc 32 when it rotates normally and vibrates slightly, and at the same time, to reduce the air leakage loss and the vortex generated by the leakage, so as to ensure the low noise characteristic of the impeller 3.

[0048] See also Figure 1 As shown, the present invention also provides a dual-impeller centrifugal fan, wherein an air inlet 11 is respectively arranged at both ends of the frame 1, the motor 2 has two output shafts, and the number of impellers 3 is two. The two impellers 3 are respectively fixedly connected to the two output shafts of the motor 2, and the two impellers 3 are respectively arranged opposite to the two air inlets 11. The motor 2 is a three-phase AC asynchronous motor with a double-axle extension, and has a variable-pole independent double winding structure, which can realize high-low speed (two / four poles) switching. When the train is running on the main line, the motor 2 runs in a two-pole high-speed state. When the train enters and exits the station, as the running speed decreases, the train control system will automatically switch the motor 2 to a four-pole low-speed state, so that the fan noise is reduced and the urban environmental noise requirements are met. The motor 2 base is made of cast aluminum stretched base, and the front and rear end covers are made of aluminum alloy material, which ensures that the motor 2 has the characteristics of light weight. At the same time, the bearings are made of wide temperature bearings, which have the characteristics of long life. The motor 2 is assembled and connected with the frame 1 through the base on the base, and the shaft extension end is inserted into the impeller 3 wheel core to drive the impeller 3 to operate.

[0049] The design flow rate of the double impeller centrifugal fan is 3.7m 3 / s, pressure greater than 1500Pa, motor power less than 10kW, and sound pressure level noise not higher than 86dB. Two fans are installed under each EMU car, and the air volume provided when running in parallel is 2×1.85m 3 / s, wind pressure is 1600Pa, and sound power is 100dB, which can meet the heat dissipation requirements of traction motor and traction inverter.

[0050] The converter cooling cabinet is hoisted on the bottom of the train, and the fan is installed in the cooling cabinet in the middle of the entire air duct. The fan dissipates heat for the traction converter and traction motor, and has high reliability requirements. When the fan is working, a large amount of cold air from the outside is sucked into the converter cabinet. The cold air first passes through the collecting effect of the air inlet duct 11 at the left and right ends and enters the left and right impellers 3 at a certain inlet air flow angle and speed. After the impeller 3 works to increase pressure and expand the pressure, it is output from the air outlet duct 12 and blown to the heat-generating components of the converter, forcing them to be cooled by the fan, and quickly taking away the heat and blowing it into the atmosphere, thereby achieving the purpose of cooling the traction converter.

[0051] Example 1: Performance and noise test of a fan matching a traditional impeller with a traditional curved air inlet duct.

[0052] Traditional impeller structural parameters: β1=36°, β2=21°, number of blades=9, blade inlet not beveled α1=0°, outlet not beveled α2=0°, blade not tilted γ=0°; traditional air inlet duct structural parameters: flow channel tapering, contraction equivalent angle φ=48°, no expansion at the rear end.

[0053] Example 2: Performance and noise test of a fan with a conventional impeller matched with a conical arc-shaped air inlet duct.

[0054] Traditional impeller structural parameters: β1=36°, β2=21°, number of blades=9, blade inlet not beveled α1=0°, outlet not beveled α2=0°, blade not tilted γ=0°; conical arc air inlet duct structural parameters: the flow channel first gradually shrinks, the equivalent contraction angle φ=53°, and the rear end expands.

[0055] Example 3: Performance and noise test of a fan with a noise reduction impeller matched with a conical arc air inlet duct.

[0056] The noise reduction impeller structural parameters are: β1=36°, β2=21°, number of blades=9, blade inlet bevel α1=5°, outlet not bevel α2=0°, blade not tilted γ=0°; conical air inlet duct structural parameters: the flow channel first gradually shrinks, the equivalent contraction angle φ=53°, and the rear end expands.

[0057] Example 4: Performance and noise test of a fan with a noise reduction impeller matched with a conical arc air inlet duct.

[0058] The noise reduction impeller structural parameters are: β1=36°, β2=21°, number of blades=9, blade inlet not beveled α1=0°, outlet beveled α2=6°, blade not tilted γ=0°; conical air inlet duct structural parameters: the flow channel first gradually shrinks, the equivalent contraction angle φ=53°, and the rear end expands.

[0059] Example 5: Performance and noise test of a fan with a noise reduction impeller matched with a conical arc air inlet duct.

[0060] The noise reduction impeller structural parameters are: β1=36°, β2=21°, number of blades=9, blade inlet not beveled α1=0°, outlet beveled α2=6°, blade tilted γ=10°; the conical air inlet duct structural parameters are: the flow channel first gradually shrinks, the equivalent contraction angle φ=53°, and the rear end expands.

[0061] Example 6: Performance and noise test of a fan with a noise reduction impeller matched with a conical arc air inlet duct.

[0062] The noise reduction impeller structural parameters are: β1=36°, β2=21°, number of blades=9, blade inlet bevel α1=5°, outlet bevel α2=6°, blade tilt γ=10°; the conical air inlet duct structural parameters are: the flow channel gradually shrinks at the equivalent contraction angle φ=53°, and the rear end expands.

[0063] Example 7: Performance and noise test of a fan with a noise reduction impeller matched with a conical arc air inlet duct.

[0064] The noise reduction impeller structural parameters are as follows: β1=36°, β2=21°, number of blades=9, blade inlet bevel α1=5°, outlet bevel α2=6°, outlet with triangular bionic serrations, blade tilt γ=10°; conical arc air inlet duct structural parameters: the flow channel gradually shrinks at the equivalent contraction angle φ=53°, and the rear end expands.

[0065] Example 8: Performance and noise test of a fan with a noise reduction impeller matched with a conical arc air inlet duct.

[0066] The noise reduction impeller structural parameters are as follows: β1=36°, β2=21°, number of blades=9, blade inlet bevel α1=5°, outlet bevel α2=6°, outlet with concave-convex curve profile, blade tilt γ=10°; conical air inlet duct structural parameters: the flow channel gradually shrinks at the equivalent contraction angle φ=53°, and the rear end expands.

[0067] Table 1 is a comparison of the performance and noise test of the traditional impeller and the noise reduction impeller at the same output flow rate.

[0068]

[0069] Note: ① The sound pressure level of A is the sound pressure level of the fan at unit flow rate (1m 3 / min), sound pressure level at unit full pressure (1Pa); ② The pressure difference ΔPa of Example 2 is obtained by comparing with Example 1, and the pressure differences ΔPa of Examples 3 to 8 are all obtained by comparing with Example 2.

[0070] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the main purpose of the present invention, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller, characterized in that: include: A frame (1), wherein an air inlet duct (11) is arranged at an end of the frame (1), and an air outlet duct (12) is arranged on a side wall of the frame (1) which is different from the side of the air inlet duct (11); A motor (2), wherein the motor (2) is arranged inside the frame (1); An impeller (3), comprising a rear wheel disc (31), a front wheel disc (32) and a plurality of blades (33), wherein the rear wheel disc (31) is fixedly connected to an output shaft of a motor (2), the plurality of blades (33) are each in the shape of an arc plate and clamped between the rear wheel disc (31) and the front wheel disc (32), the plurality of blades (33) are arranged symmetrically in a circumferential direction on a radial plane of the impeller (3), and an air inlet of the front wheel disc (32) is arranged opposite to an air inlet duct (11); The blade (33) forms an air outlet end (331) located on the outer circle of the rotation path ring of the blade (33) and an air inlet end (332) located on the inner circle of the rotation path ring of the blade (33) on the radial plane of the impeller (3), respectively; a tangent line of the air outlet end (331) on the outer circle of the rotation path ring and an extension line of the air outlet end (331) form an angle of β1 degrees, and 30°≤β1≤60°; a tangent line of the air inlet end (332) on the inner circle of the rotation path ring and an extension line of the air inlet end (332) form an angle of β2 degrees, and 15°≤β2≤35°; The side of the blade (33) located at the air outlet end (331) is an air outlet cutting edge (333), and the side of the blade (33) located at the air inlet end (332) is an air inlet cutting edge (334). An extended line of the air outlet cutting edge (333) forms an angle of α1 degrees with the central axis of the impeller (3), and 0<α1≤9°; an extended line of the air inlet cutting edge (334) forms an angle of α2 degrees with the central axis of the impeller (3), and 0<α2≤9°.

2. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 1, characterized in that: The line connecting the two end points of the wind inlet cutting edge (334) is an extension line of the wind inlet cutting edge (334), and the wind inlet cutting edge (334) forms a continuously waving concave-convex structure relative to the extension line.

3. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 1, characterized in that: The line connecting the two end points of the air outlet cutting edge (333) is the extension line of the air outlet cutting edge (333), and the air outlet cutting edge (333) forms a continuously fluctuating concave-convex structure relative to the extension line.

4. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 1, characterized in that: A plane rotating around the central axis of the impeller (3) is a tangent plane, and the intersection of the tangent plane and the blade (33) is a projection plane of the blade (33). An extended line of the projection plane forms an angle of γ degrees with the central axis of the impeller (3), and 0°<γ≤20°.

5. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 1, characterized in that: The air inlet duct (11) forms a cylindrical air duct structure along the air flow direction, which first contracts inwards and then expands outwards.

6. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 5, characterized in that: The air inlet end of the air inlet duct (11) is in the shape of a cone that gradually contracts along the airflow direction, and the contraction angle of the cone is φ and 40°≤φ≤60°.

7. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 5, characterized in that: The air outlet end of the air inlet duct (11) is sleeved in the front wheel disc (32), the overlap degree of the air inlet duct (11) and the front wheel disc (32) in the axial direction of the central axis of the impeller (3) is h=2mm-6mm, and the clearance δ between the air inlet duct (11) and the front wheel disc (32) in the radial direction of the central axis of the impeller (3) is (0.5%-1%)D m , where D m is the inner diameter of the front wheel disc (32) on the radial plane.

8. A double-impeller centrifugal fan with a noise-reducing centrifugal impeller according to claim 1, characterized in that: An air inlet duct (11) is respectively arranged at both ends of the frame (1); the motor (2) has two output shafts; the number of the impellers (3) is two; the two impellers (3) are respectively fixedly connected to the two output shafts of the motor (2); and the two impellers (3) are respectively arranged opposite to the two air inlets (11).

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