A compact low-noise centrifugal fan

Abstract

The application relates to a fan technical field, in particular to a compact low-noise centrifugal fan. The compact low-noise centrifugal fan comprises a volute body, an impeller arranged in the volute body, and a driving motor mounted on the volute body, the output shaft of the driving motor is connected with the impeller, an air inlet and an air outlet are arranged on the volute body; a volute tongue is arranged in the volute body; the volute body comprises a volute framework, a volute panel and a volute hole plate; the volute hole plate is arranged in the volute framework, and the volute panel covers the volute framework; sound-absorbing material is filled between the volute panel and the volute hole plate, and a plurality of sound-absorbing holes are uniformly distributed on the volute hole plate. Therefore, the noise can be well absorbed by the sound-absorbing material through the sound-absorbing holes, and the noise reduction effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fan, in particular to a compact low-noise centrifugal fan. BACKGROUND

[0002] When using centrifugal fan for ventilation and heat dissipation, the operation noise of the fan is harmful to human body, and reducing the operation noise of the fan is helpful to reduce the system noise. Centrifugal fan has the characteristics of large flow coefficient, high pressure coefficient, high efficiency and low relative noise, and is often used in special application fields. In the manned space field, due to the small space of the use environment, the noise generated and propagated by the conventional centrifugal fan has a more obvious influence on the astronauts, so when selecting a low-noise centrifugal fan, passive noise reduction design is also needed, and various measures are taken to reduce the operation noise of the fan.

[0003] In the prior art, a low-noise rectangular centrifugal fan is disclosed in the patent with the publication number CN212508886U, which comprises a centrifugal fan body, a rectangular shell sleeved outside the centrifugal fan body, and a power motor fixed on the rectangular shell, and the centrifugal fan body and the rectangular shell are filled with a sound-absorbing filler; the centrifugal fan body comprises a fan volute, an air inlet arranged on the fan volute, an air outlet passage, and an impeller arranged in the fan volute; a sound-absorbing plate is fixed on the inner wall of the fan volute and the air outlet passage.

[0004] In the above prior art, the panel of the fan volute often adopts a solid plate structure, and the noise reduction effect is not obvious. Therefore, it is necessary to provide a centrifugal fan with more obvious noise reduction effect. SUMMARY

[0005] The main purpose of the present application is to provide a compact low-noise centrifugal fan, which aims to solve the above technical problems.

[0006] In order to achieve the above purpose, the present application provides a compact low-noise centrifugal fan, which comprises a volute body, an impeller arranged in the volute body, and a driving motor mounted on the volute body, the output shaft of the driving motor is connected with the impeller, and an air inlet and an air outlet are arranged on the volute body; a volute tongue is arranged in the volute body; the volute body comprises a volute skeleton, a volute panel and a volute hole plate; the volute hole plate is arranged in the volute skeleton, and the volute panel covers the volute skeleton; sound-absorbing material is filled between the volute panel and the volute hole plate, and a plurality of sound-absorbing holes are uniformly distributed on the volute hole plate.

[0007] Preferably, an inner ring body and a current collector are installed at the air inlet; the inner ring body comprises a cylinder part, a circular ring body integrally formed on the inner wall of one end of the cylinder part, and a flange edge integrally formed on the outer wall of the other end of the cylinder part; a plurality of sound-absorbing holes are uniformly distributed on the cylinder part and the circular ring body respectively; the current collector has a trumpet mouth shape, the inner ring body is sleeved on the current collector, and sound-absorbing material is filled between the inner wall of the inner ring body and the outer surface of the current collector.

[0008] Preferably, the sound-absorbing material is melamine foam or polyurethane foam; the sound-absorbing material is wrapped with silk cloth; the perforation rate of the sound-absorbing hole is 15% to 25%.

[0009] Preferably, the sound-absorbing hole is a through hole with a diameter of φ2.5mm, and three adjacent sound-absorbing holes are distributed in a regular triangle shape, and the side length of the regular triangle is 6mm.

[0010] Preferably, the impeller comprises a disc, blades, and an impeller inlet sleeve; a plurality of blades are uniformly distributed in a ring shape on the disc, the impeller inlet sleeve is sleeved on the outer part of all blades close to one end of the inner ring body; the small end of the current collector extends into the impeller inlet sleeve after passing through the center hole of the circular ring body, and the nesting length of the small end of the current collector and the impeller inlet sleeve is L, which satisfies L=5mm to 10mm.

[0011] Preferably, the tangential direction of the inlet edge of the impeller inlet sleeve is V1, the tangential direction of the outlet edge of the current collector is V2, the included angle between the tangential direction V1 and the tangential direction V2 is δ, which satisfies δ=5° to 10°.

[0012] Preferably, a flow guide cover in the shape of a trumpet mouth is installed on the output shaft of the driving motor; the large end surface of the flow guide cover abuts against the surface of the disc; the inner hole of the small end of the flow guide cover is sleeved on the output shaft of the driving motor, a slotted conical nut is screwed on the end part of the output shaft and presses the flow guide cover; the outer cylindrical surface of the slotted conical nut and the outer surface of the flow guide cover smoothly transition.

[0013] Preferably, a bearing cover and a bearing are installed on the shell of the driving motor, the bearing is sleeved on the output shaft, and the bearing cover abuts against the right end surface of the outer ring of the bearing; a disc mounting pipe is integrally formed in the center of the disc, the disc mounting pipe is sleeved on the output shaft of the driving motor, and a flat key is arranged between the disc mounting pipe and the output shaft; a retaining ring is sleeved on the output shaft and located between the bearing and the disc mounting pipe; a locking nut is screwed on the output shaft; when the locking nut is tightened, the locking nut abuts against the right end surface of the disc mounting pipe, the disc mounting pipe is axially pushed to press the retaining ring, and the retaining ring is pressed against the right end surface of the inner ring of the bearing.

[0014] Preferably, a first annular boss is integrally formed at the left end of the outer circumferential surface of the check ring, and a second annular boss is integrally formed at the right end of the outer circumferential surface of the check ring; the outer diameter of the second annular boss is greater than the outer diameter of the first annular boss; an annular groove is formed between the second annular boss and the first annular boss; the central hole of the bearing cover comprises a first hole section and a second hole section from left to right; the diameter of the second hole section is greater than the diameter of the first hole section; the check ring is arranged in the central hole of the bearing cover, and the first annular boss is located in the first hole section, and the second annular boss is located in the second hole section.

[0015] Preferably, the volute tongue is provided with a flow guide surface and a mounting plane; a threaded hole is arranged on the mounting plane; the height from one end of the flow guide surface to the mounting plane is h1, and the height from the other end of the flow guide surface to the mounting plane is h2; the curvature radius of the one end with a distance of h1 is R1, and the curvature radius of the other end with a distance of h2 is R2, which satisfy R1>R2 and h1

[0016] Due to the adoption of the above technical solutions, the application has the following advantages:

[0017] (1) In the application, the volute shell body comprises a volute hole plate, a volute framework and a volute panel from inside to outside, a plurality of noise elimination holes are uniformly distributed on the volute hole plate, and sound-absorbing material is filled between the volute panel and the volute hole plate, so that noise can be well absorbed by the sound-absorbing material through the noise elimination holes, thereby improving the noise reduction effect.

[0018] (2) In the application, the collector and the impeller inlet ring are designed in a sleeve opening type, which increases the sealing between the collector and the impeller inlet ring and reduces the leakage loss.

[0019] (3) In the application, the tangential direction of the inlet edge of the impeller inlet ring is V1, the tangential direction of the outlet edge of the collector is V2, and the included angle between the tangential direction V1 and the tangential direction V2 is δ, which satisfies δ=5°-10°. Through the above structural design, the interference of the leakage airflow on the working airflow can be reduced, and the inlet aerodynamic noise can be reduced.

[0020] (4) In the application, the volute tongue has a flow guide surface with an inclined curved surface shape, which can reduce the amplitude of the main frequency of the fan noise, thereby reducing the overall operation noise of the fan. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0022] Figure 1 A sectional view of the centrifugal fan provided by the present application;

[0023] Figure 2 A sectional view of the centrifugal fan provided by the present application; Figure 1 An enlarged view of A in the above figure;

[0024] Figure 3 A schematic view of the included angle between the tangential direction of the inlet edge of the impeller inlet ring and the outlet edge of the collector in the present application;

[0025] Figure 4 A sectional view of the centrifugal fan provided by the present application; Figure 1 An enlarged view of B in the above figure;

[0026] Figure 5 A schematic view of the structure of the driving motor in the present application;

[0027] Figure 6 A perspective view of the volute body in the present application Figure 1 ;

[0028] Figure 7 A perspective view of the volute body in the present application Figure 2 ;

[0029] Figure 8 A perspective view of the volute body in the present application Figure 1 ;

[0030] Figure 9 A perspective view of the volute body in the present application Figure 2 ;

[0031] Figure 10 A perspective view of the inner ring body in the present application;

[0032] Figure 11 A schematic view of the structure of the fairing in the present application;

[0033] Figure 12 A main sectional view of the slotted conical nut in the present application;

[0034] Figure 13 A right view of the slotted conical nut in the present application;

[0035] Figure 14 A perspective view of the volute tongue in the present application Figure 1 ;

[0036] Figure 15 A perspective view of the volute tongue in the present application Figure 2 ;

[0037] Figure 16 A schematic view of the arrangement rule of the sound absorbing hole in the present application.

[0038] BRIEF DESCRIPTION OF DRAWINGS 1, volute body; 1a, air inlet; 1b, air outlet; 1c, volute skeleton; 1d, volute hole plate; 1e, volute panel; 1f, mounting foot plate; 1g, reinforcing rib plate; 1h, motor mounting sleeve; 1j, current collector mounting ring; 2, impeller; 2a, impeller inlet sleeve ring; 2b, blade; 2c, wheel disc; 2d, wheel disc mounting pipe; 3, driving motor; 3a, output shaft; 4, sound-absorbing material; 5, inner ring body; 5a, cylinder part; 5b, circular ring body; 5c, flange edge; 6, current collector; 7, flow guide cover; 8, flat key; 9, check ring; 9a, first annular boss; 9b, second annular boss; 10, locking nut; 11, slotted conical nut; 12, bearing cover; 12a, first hole section; 12b, second hole section; 13, bearing; 14, volute tongue; 14a, flow guide surface; 14b, mounting plane; 14c, threaded hole. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0040] It should be noted that all directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directionality indications also change accordingly.

[0041] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope claimed by the present application.

[0042] A compact low-noise centrifugal fan, comprising a volute body 1, an impeller 2 arranged inside the volute body 1, and a driving motor 3 mounted on the volute body 1, the output shaft 3a of the driving motor 3 being connected with the impeller 2, and an air inlet 1a and an air outlet 1b being arranged on the volute body 1; a volute tongue 14 is arranged inside the volute body 1; the volute body 1 comprises a volute framework 1c, a volute panel 1e, and a volute hole plate 1d; the volute hole plate 1d is arranged in the volute framework 1c, and the volute panel 1e covers the volute framework 1c; sound-absorbing material 4 is filled between the volute panel 1e and the volute hole plate 1d, and a plurality of sound-absorbing holes are uniformly distributed on the volute hole plate 1d.

[0043] As shown in Figure 1 and Figure 10 , an inner ring body 5 and a current collector 6 are mounted at the air inlet 1a; the inner ring body 5 comprises a cylinder part 5a, a circular ring body 5b integrally formed on the inner wall of one end of the cylinder part 5a, and a flange edge 5c integrally formed on the outer wall of the other end of the cylinder part 5a; a plurality of sound-absorbing holes are uniformly distributed on the cylinder part 5a and the circular ring body 5b, respectively; the current collector 6 is in the shape of a bell mouth, the inner ring body 5 is sleeved on the current collector 6, and sound-absorbing material 4 is filled between the inner wall of the inner ring body 5 and the outer surface of the current collector 6.

[0044] In this embodiment, the sound-absorbing material 4 is melamine foam or polyurethane foam; the sound-absorbing material 4 is wrapped with silk cloth, which can prevent the debris generated by the sound-absorbing material 4 from entering the inside of the fan.

[0045] In this embodiment, the perforation rate of the sound-absorbing holes is 15% to 25%. The specific perforation rate needs to be adjusted according to the main frequency of the fan noise, and the perforation rule is shown in Figure 16 , the sound-absorbing holes are through holes with a diameter of φ2.5mm, and three adjacent sound-absorbing holes are distributed in a regular triangle, and the side length of the regular triangle is 6mm.

[0046] As shown in Figure 1 , Figure 2 , the impeller 2 comprises a disc 2c, blades 2c, and an impeller inlet sleeve 2a; a plurality of blades 2c are annularly and uniformly distributed on the disc 2c, and the impeller inlet sleeve 2a is sleeved on the outside of all the blades 2c close to one end of the inner ring body 5; the small end of the current collector 6 extends into the impeller inlet sleeve 2a after passing through the center hole of the circular ring body 5b, and the nesting length of the small end of the current collector 6 and the impeller inlet sleeve 2a is L, which satisfies L=5mm to 10mm. The current collector 6 and the impeller inlet sleeve 2a adopt a sleeve opening design, which increases the sealing between the impeller inlet sleeve 2a and the current collector 6 and reduces the leakage loss.

[0047] As shown in Figure 3As shown, the tangential direction of the inlet edge of the impeller inlet collar 2a is V1, the tangential direction of the outlet edge of the collector 6 is V2, the included angle between the tangential direction V1 and the tangential direction V2 is δ, and δ satisfies 5°-10°. Through the above structural design, the interference of the leakage airflow on the working airflow can be reduced, and the inlet aerodynamic noise can be reduced.

[0048] In combination Figure 1 , Figure 11 As shown, a flow guide cover 7 in the shape of a bell mouth is mounted on the output shaft 3a of the driving motor 3; the large end face of the flow guide cover 7 abuts against the surface of the wheel disc 2c; the inner hole of the small end of the flow guide cover 7 is sleeved on the output shaft 3a of the driving motor 3, and a slotted conical nut 11 is screwed on the end of the output shaft 3a of the driving motor 3 and presses against the flow guide cover 7; the outer cylindrical surface of the slotted conical nut 11 and the outer surface of the flow guide cover 7 are smoothly transitioned.

[0049] In combination Figure 1 and Figure 4 As shown, a bearing cover 12 and a bearing 13 are mounted on the housing of the driving motor 3, and the bearing 13 is sleeved on the output shaft 3a, and the bearing cover 12 abuts against the right end face of the outer ring of the bearing 13; a wheel disc mounting pipe 2d is integrally formed in the center of the wheel disc 2c, the wheel disc mounting pipe 2d is sleeved on the output shaft 3a of the driving motor 3, and a flat key 8 is arranged between the wheel disc mounting pipe 2d and the output shaft 3a; a retaining ring 9 is sleeved on the output shaft 3a and located between the bearing 13 and the wheel disc mounting pipe 2d; a locking nut 10 is screwed on the output shaft 3a; when the locking nut 10 is tightened, the locking nut 10 abuts against the right end face of the wheel disc mounting pipe 2d, axially pushes the wheel disc mounting pipe 2d to press the retaining ring 9, and makes the retaining ring 9 press against the right end face of the inner ring of the bearing 13.

[0050] In combination Figure 4 As shown, a first annular boss 9a is integrally formed on the left end of the outer circumferential surface of the retaining ring 9, and a second annular boss 9b is integrally formed on the right end; the outer diameter of the second annular boss 9b is greater than the outer diameter of the first annular boss 9a; an annular groove 9c is formed between the second annular boss 9b and the first annular boss 9a; the center hole of the bearing cover 12 includes a first hole section 12a and a second hole section 12b from left to right; the diameter of the second hole section 12b is greater than the diameter of the first hole section 12a; the retaining ring 9 is arranged in the center hole of the bearing cover 12, and the first annular boss 9a is located in the first hole section 12a, and the second annular boss 9b is located in the second hole section 12b.

[0051] In combination Figure 15 and Figure 16As shown, the volute tongue 14 is provided with a flow guide surface 14a and a mounting plane 14b; a threaded hole 14c is arranged on the mounting plane 14b; the height of one end of the flow guide surface 14a to the mounting plane 14b is h1, and the height of the other end of the flow guide surface 14a to the mounting plane 14b is h2; the curvature radius of the one end with the height of h1 is R1, and the curvature radius of the other end with the height of h2 is R2, which satisfy: R1>R2, and h1<h2; the flow guide surface 14a is an inclined curved surface with the curvature radius gradually decreasing from R1 to R2. In addition, in order to reduce the weight of the volute tongue 14, the back side of the volute tongue 14 is hollowed out.

[0052] Compared with the traditional straight volute tongue, the volute tongue 14 in the embodiment has the flow guide surface 14a with the inclined curved surface shape, and thus has the following effects:

[0053] ①Change the air flow impact mode: the volute tongue 14 with the inclined curved surface can make the air flow ejected from the impeller 2 contact it at a relatively gentler angle, avoid the strong vortex and pressure pulsation caused by the sharp impact of the air flow on the volute tongue 14, and thus reduce the noise caused by the impact.

[0054] ②Disturb the vortex generation: the volute tongue 14 with the inclined curved surface can disturb the state of the air flow originally regularly forming strong vortexes, so as to reduce the strength and size of the vortexes and the aerodynamic noise caused by the vortexes.

[0055] ③Disperse the noise frequency: change the inherent frequency characteristics of the air flow and the volute tongue 14, so that the noise frequency components become more dispersed, avoid the energy being concentrated in certain specific frequencies to produce obvious harsh and high-decibel noise, and thus reduce the noise intensity perceived by the human ear as a whole.

[0056] In the embodiment, the mounting plane 14b of the volute tongue 14 is provided with the threaded hole 14c, and the threaded hole 14c and the volute shell body 1 are connected by screws, so that the volute tongue 14 and the volute shell body 1 form a detachable connection structure, and thus the volute tongue 14 is convenient to replace.

[0057] In the embodiment, the volute skeleton 1c, the volute panel 1e, the volute hole plate 1d, and the sound-absorbing material 4 filled between the volute panel 1e and the volute hole plate 1d jointly constitute an integrated noise reduction volute structure. The volute tongue 14 inside the volute body 1 is a detachable inclined volute tongue structure; the nesting structure design of the collector 6 and the impeller inlet collar 2a forms a small-inclination sleeve-port type collector structure; the fairing 7 at the impeller 2 inlet and the slotted conical nut 11 jointly form a two-section fairing structure; the impeller 2 is composed of a disc 2c, blades 2c, and an impeller inlet collar 2a, and the installation mode of the impeller 2 forms a single-end rotary arm impeller installation structure. Through the above structure design, the purpose of greatly reducing the operating noise of the centrifugal fan can be achieved. The centrifugal fan provided in the embodiment can greatly reduce the operating noise of the fan in the full frequency band, and the effect of suppressing high-frequency noise is particularly obvious. Using the same fan model for noise comparison, the noise at the air inlet side is reduced by 4 dB(A) to 6 dB(A), and the shell noise is reduced by 5 dB(A) to 8 dB(A).

[0058] In the embodiment, the volute skeleton 1c and the volute hole plate 1d inside the volute skeleton 1c are integrally formed by 3D printing. Figure 8 As shown in Figs. 1 and 2, the bottom of the volute skeleton 1c is integrally formed with a mounting foot plate 1f, and bolt through holes are arranged on the mounting foot plate 1f. The mounting foot plate 1f is used for mounting and fixing the entire fan. A reinforcing rib plate 1g is arranged between the mounting foot plate 1f and the volute skeleton 1c to strengthen the structure and improve the structural strength of the volute body 1.

[0059] As shown in Figs. 1 and 2, the bottom of the volute skeleton 1c is integrally formed with a mounting foot plate 1f, and bolt through holes are arranged on the mounting foot plate 1f. The mounting foot plate 1f is used for mounting and fixing the entire fan. A reinforcing rib plate 1g is arranged between the mounting foot plate 1f and the volute skeleton 1c to strengthen the structure and improve the structural strength of the volute body 1. Figure 8 As shown in Figs. 1 and 2, the bottom of the volute skeleton 1c is integrally formed with a mounting foot plate 1f, and bolt through holes are arranged on the mounting foot plate 1f. The mounting foot plate 1f is used for mounting and fixing the entire fan. A reinforcing rib plate 1g is arranged between the mounting foot plate 1f and the volute skeleton 1c to strengthen the structure and improve the structural strength of the volute body 1. Figure 9 As shown in Figs. 1 and 2, the bottom of the volute skeleton 1c is integrally formed with a mounting foot plate 1f, and bolt through holes are arranged on the mounting foot plate 1f. The mounting foot plate 1f is used for mounting and fixing the entire fan. A reinforcing rib plate 1g is arranged between the mounting foot plate 1f and the volute skeleton 1c to strengthen the structure and improve the structural strength of the volute body 1. Figure 1 As shown in Figs. 1 and 2, the bottom of the volute skeleton 1c is integrally formed with a mounting foot plate 1f, and bolt through holes are arranged on the mounting foot plate 1f. The mounting foot plate 1f is used for mounting and fixing the entire fan. A reinforcing rib plate 1g is arranged between the mounting foot plate 1f and the volute skeleton 1c to strengthen the structure and improve the structural strength of the volute body 1.

[0060] In summary, the assembly steps of the compact low-noise centrifugal fan provided in the embodiment are as follows:

[0061] Step 1: The driving motor 3 is mounted on the volute body 1 by screws. Specifically, the driving motor 3 is inserted into the motor mounting sleeve 1h on the volute skeleton 1c, and the driving motor 3 is sealed with the mounting sleeve 1h to prevent high-pressure gas in the inner cavity of the volute body 1 from leaking to the outside.

[0062] Step 2: A check ring 9 is mounted on the output shaft 3a of the driving motor 3. As shown inFigure 4 As shown, the left end of the check ring 9 is in close contact with the inner ring of the bearing 13 of the driving motor 3, axial fixation is completed, the check ring 9 is arranged in the stepped hole in the center of the bearing cover 12, the first annular boss 9a, the second annular boss 9b and the annular groove 9c on the check ring 9 and the first hole segment 12a and the second hole segment 12b of the bearing cover 12 jointly form a labyrinth structure, which is used to shield the excess in the internal working medium of the fan from being transmitted to the inside of the bearing 13.

[0063] Step 3: Install the flat key 8 on the output shaft 3a of the driving motor 3.

[0064] Step 4: Install the impeller 2 on the output shaft 3a of the driving motor 3, the key groove on the wheel disc installation pipe 2d is in transition fit with the flat key 8.

[0065] Step 5: Install the lock nut 10 on the output shaft 3a of the driving motor 3, and tighten the lock nut 10, so that the lock nut 10 abuts against the right end surface of the wheel disc installation pipe 2d, axially pushes the wheel disc installation pipe 2d to tightly push the check ring 9, so that the check ring 9 tightly abuts against the right end surface of the inner ring of the bearing 13. Thus, the impeller 2 is stably installed on the output shaft 3a.

[0066] Step 6: Install the flow guide cover 7 on the output shaft 3a of the driving motor 3, specifically, the large end surface of the flow guide cover 7 abuts against the surface of the wheel disc 2c, which can prevent the wheel disc 2c from vibrating and improve the rigidity of the wheel disc 2c. The inner hole of the small end of the flow guide cover 7 is sleeved on the installation stop of the output shaft 3a, the slotted conical nut 11 is screwed on the end of the output shaft 3a and tightly abuts against the flow guide cover 7, and the outer cylindrical surface of the slotted conical nut 11 is smoothly transitioned with the outer surface of the flow guide cover 7. The flow guide cover 7 is processed by using light material, which can reduce the weight of the rotating shaft system.

[0067] Step 7: Install the inner ring body 5 at the air inlet 1a end of the volute body 1 and fill the sound-absorbing material 4, and insert the current collector 9 in the inner ring body 5. Specifically, the flange edge 5c of the inner ring body 5 and the large end of the current collector 6 are jointly installed on the current collector installation ring 1j at the air inlet 1a by screws.

[0068] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, any equivalent structural transformation made under the inventive concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A compact, low-noise centrifugal fan, comprising a volute body (1), an impeller (2) disposed inside the volute body (1), and a drive motor (3) mounted on the volute body (1), wherein the output shaft (3a) of the drive motor (3) is connected to the impeller (2), and an air inlet (1a) and an air outlet (1b) are provided on the volute body (1); a volute tongue (14) is provided inside the volute body (1); characterized in that: The volute body (1) includes a volute skeleton (1c), a volute panel (1e), and a volute perforated plate (1d); the volute perforated plate (1d) is disposed inside the volute skeleton (1c), and the volute panel (1e) covers the volute skeleton (1c); a sound-absorbing material (4) is filled between the volute panel (1e) and the volute perforated plate (1d), and a plurality of sound-absorbing holes are evenly distributed on the volute perforated plate (1d); The impeller (2) includes a disc (2c), blades (2b) and an impeller inlet collar (2a); A bearing cover (12) and a bearing (13) are installed on the housing of the drive motor (3), and the bearing (13) is sleeved on the output shaft (3a), with the bearing cover (12) abutting against the right end face of the outer ring of the bearing (13). A wheel mounting tube (2d) is integrally formed at the center of the wheel (2c). The wheel mounting tube (2d) is sleeved on the output shaft (3a) of the drive motor (3), and a flat key (8) is provided between the wheel mounting tube (2d) and the output shaft (3a). A retaining ring (9) is fitted on the output shaft (3a), and the retaining ring (9) is located between the bearing (13) and the wheel mounting tube (2d); a locking nut (10) is screwed on the output shaft (3a); when the locking nut (10) is tightened, the locking nut (10) abuts against the right end face of the wheel mounting tube (2d), axially pushing the wheel mounting tube (2d) to press against the retaining ring (9), and making the retaining ring (9) press against the right end face of the inner ring of the bearing (13); A first annular boss (9a) is integrally formed on the left end of the outer peripheral surface of the retaining ring (9), and a second annular boss (9b) is integrally formed on the right end; the outer diameter of the second annular boss (9b) is larger than the outer diameter of the first annular boss (9a); an annular groove (9c) is formed between the second annular boss (9b) and the first annular boss (9a). The central hole of the bearing cap (12) includes a first hole section (12a) and a second hole section (12b) from left to right; the diameter of the second hole section (12b) is larger than the diameter of the first hole section (12a); The retaining ring (9) is disposed in the center hole of the bearing cover (12), and the first annular boss (9a) is located in the first hole section (12a), and the second annular boss (9b) is located in the second hole section (12b); The volute tongue (14) has a guide surface (14a) and a mounting surface (14b); a threaded hole (14c) is provided on the mounting surface (14b); the height from one end of the guide surface (14a) to the mounting surface (14b) is h1, and the height from the other end to the mounting surface (14b) is h2; the radius of curvature of the end at the distance h1 is R1, and the radius of curvature of the end at the distance h2 is R2, satisfying: R1>R2, and h1<h2; the guide surface (14a) is an inclined surface with a radius of curvature that gradually decreases from R1 to R2.

2. The compact, low-noise centrifugal fan as described in claim 1, characterized in that, An inner ring (5) and a collector (6) are installed at the air inlet (1a); The inner ring (5) includes a cylindrical part (5a), an annular body (5b) integrally formed on the inner wall of one end of the cylindrical part (5a), and a flange edge (5c) integrally formed on the outer wall of the other end of the cylindrical part (5a); a plurality of sound-absorbing holes are evenly distributed on the cylindrical part (5a) and the annular body (5b); The collector (6) is shaped like a horn, and the inner ring (5) is fitted on the collector (6), and sound-absorbing material (4) is filled between the inner wall of the inner ring (5) and the outer surface of the collector (6).

3. A compact, low-noise centrifugal fan as described in claim 1 or 2, characterized in that, The sound-absorbing material (4) is melamine foam or polyurethane foam; the sound-absorbing material (4) is wrapped with silk cloth; the perforation rate of the sound-absorbing holes is 15% to 25%.

4. A compact, low-noise centrifugal fan as described in claim 1 or 2, characterized in that, The silencing holes are through holes with a diameter of φ2.5mm. Three adjacent silencing holes are arranged in an equilateral triangle with a side length of 6mm.

5. A compact, low-noise centrifugal fan as described in claim 2, characterized in that, Multiple blades (2b) are evenly distributed in a ring on the impeller (2c). The impeller inlet collar (2a) is fitted around the outside of all blades (2b) near the end of the inner ring (5). The small end of the collector (6) passes through the central hole of the ring (5b) and extends into the impeller inlet collar (2a). The nesting length between the small end of the collector (6) and the impeller inlet collar (2a) is L, which satisfies L=5mm~10mm.

6. A compact, low-noise centrifugal fan as described in claim 5, characterized in that, The inlet edge tangential of the impeller inlet collar (2a) is V1, and the outlet edge tangential of the collector (6) is V2. The angle between the tangential V1 and the tangential V2 is δ, which satisfies δ=5°~10°.

7. A compact, low-noise centrifugal fan as described in claim 5, characterized in that, A funnel-shaped shroud (7) is installed on the output shaft (3a) of the drive motor (3). The large end face of the flow guide (7) abuts against the surface of the wheel (2c); The inner hole of the small end of the flow guide (7) is sleeved on the output shaft (3a) of the drive motor (3), and a slotted conical nut (11) is screwed into the end of the output shaft (3a) of the drive motor (3) and tightens the flow guide (7). The outer cylindrical surface of the slotted conical nut (11) smoothly transitions with the outer surface of the flow guide (7).

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