A volute structure of a centrifugal fan

Abstract

The present invention relates to a volute structure of a centrifugal fan, comprising a volute tongue, a front cover plate, a rear cover plate and a volute ring wall, wherein the volute ring wall comprises a first ring wall and a second ring wall, wherein the first ring wall is connected between the front cover plate and the rear cover plate and encloses a volute cavity with the front cover plate and the rear cover plate, wherein the second ring wall is arranged in the volute cavity and divides the volute cavity into an outer cavity and an inner cavity, wherein the rear edge of the second ring wall is connected with the rear cover plate, wherein the front side edge of the second ring wall is gradually inclined backward from the middle part to connect the outer cavity and the inner cavity, and an air guide port arranged near the air outlet is provided on the second ring wall along the axial direction. During the use of the centrifugal fan, part of the air flow is discharged from the air outlet through the outer cavity, and the other part of the air flow is circulated through the inner cavity to the air guide port at the top of the inner cavity and discharged through the air outlet, wherein the arrangement of the second ring wall plays a good role in diversion, thereby reducing gas reflux and eddy current problems, thereby reducing fan noise and improving fan efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of range hoods, and in particular to a volute structure of a centrifugal fan. Background Art

[0002] Household range hoods use multi-blade centrifugal fans for air intake and exhaust. The fan is generally composed of a volute, a motor, an impeller, etc. The tongue-shaped protrusion in the volute is called the volute tongue, and its main function is to separate the flowing gas and prevent the gas from circulating in the volute. Due to the high gas pressure and complex flow near the volute tongue, the flow noise and rotation noise generated near the volute tongue are the main noise sources of the centrifugal fan. Reducing the noise near the volute tongue can significantly reduce the noise of the range hood.

[0003] The Chinese patent application "A fan volute for a range hood" (application number: CN201610111243.1) with application publication number CN105526193A discloses a structure, which includes a volute tongue, which includes a volute tongue inner wall, and the volute tongue forms a closed cavity, in which at least one longitudinal partition is arranged along the axial direction of the volute, and a plurality of radial partitions are arranged along the axial direction perpendicular to the volute, and the longitudinal partition and the radial partition divide the cavity into a plurality of independent closed silencing cavities, and a hole is opened on the inner wall portion of the volute tongue corresponding to each silencing cavity. The above structure divides the cavity in the volute tongue into a plurality of independent closed small cavities, and the small cavities and the corresponding holes opened on the side walls form a Helmholtz resonator. According to the Helmholtz resonance principle, after the sound propagates, the sound wave close to the natural frequency of the resonator resonates with the resonator, and during the vibration process, the air column in the cavity rubs against the inner wall of the cavity to consume sound energy, thereby absorbing and reducing noise.

[0004] The above structure reduces the fan noise to a certain extent by setting up a silencer cavity. However, due to the small space at the volute tongue, the gas is difficult to be discharged at one time, and the residual gas is easy to flow back and form vortices, resulting in reduced fan efficiency and vortex noise, which in turn causes the fan to still have a large noise. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a volute structure of a centrifugal fan which can effectively break vortex and reduce gas backflow, thereby reducing fan noise and improving fan efficiency in view of the current status of the prior art.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a volute structure of a centrifugal fan, comprising a volute tongue, a front cover plate, a rear cover plate and a volute ring wall, the front cover plate and the rear cover plate are arranged at intervals in front and behind, the volute ring wall is arranged between the front cover plate and the rear cover plate, the volute tongue is arranged on a first end of the volute ring wall and is arranged close to the air outlet of the volute, and is characterized in that: the volute ring wall comprises a first ring wall and a second ring wall, the first ring wall is connected between the front cover plate and the rear cover plate and encloses a volute cavity with the front cover plate and the rear cover plate, the second ring wall is arranged in the volute cavity and divides the volute cavity into an outer cavity and an inner cavity, the rear edge of the second ring wall is connected to the rear cover plate, the front side edge of the second ring wall is at least gradually tilted backward from the middle portion to connect the outer cavity and the inner cavity, and an air guide port arranged close to the air outlet is axially opened on the second ring wall.

[0007] Preferably, the rear edge of the second annular wall is connected to the front side of the rear cover plate, the top of the front edge of the second annular wall is connected to the rear side of the front cover plate, and the minimum width of the second annular wall in the axial direction is 0.25 to 0.5 times the maximum width. An air inlet is provided in the central part of the front cover plate, and the second annular wall is arranged concentrically with the air inlet. This structure is adopted to facilitate a better diversion effect.

[0008] As an improvement, the bottom of the volute tongue is provided with an opening corresponding to the air guide port, and a guide structure is provided above the opening to guide the airflow in the volute inner cavity to the volute air outlet. With this structure, the airflow is directly transported from the inner cavity formed by the second annular wall to the air outlet, which can effectively break the vortex and reduce gas reflux.

[0009] In the above scheme, the air guide port penetrates the second ring wall axially so that the second ring wall forms an open-loop structure, the first end of the second ring wall is connected to the edge of the side of the volute tongue opening away from the air outlet, and a gap is formed between the second end of the second ring wall and the lower surface of the volute tongue close to the air outlet. With such a structure, when the fan flow is small, the guide structure can be in a closed state, and part of the airflow diverted from the inner cavity formed by the second ring wall is discharged from the above gap and discharged through the air outlet.

[0010] As an improvement, the volute tongue has a volute tongue inner wall, the two sides of the volute tongue are closed to form a cavity, the outer side of the volute tongue is provided with a first baffle extending into the cavity along the volute tongue outer wall, the guide channel is formed between the upper part of the first baffle and the corresponding volute tongue inner wall, the lower part of the first baffle and the cavity inner wall enclose a guide cavity, the opening is opened at the bottom of the guide cavity, and the guide channel and the guide cavity together constitute the guide structure. Such a guide structure is used to break the vortex and reduce gas reflux.

[0011] In a further improvement, the guide cavity is further provided with a guide block capable of covering or opening the opening. When the fan is small, the opening can be covered by the guide block, and when the fan flow is large, the opening can be opened by the guide block.

[0012] Preferably, a sensor capable of detecting the air volume is disposed on the inner wall of the second ring wall, and an adjusting component capable of adjusting the opening and closing of the guide block relative to the opening according to the air volume is disposed on the volute tongue. With this structure, when the air volume is small, the adjusting component does not work, and the conventional structure of the volute tongue meets the demand. When the air volume is large, the adjusting component drives the guide block to move under the impact of the wind flow, thereby opening the opening and playing the role of breaking the vortex and reducing gas reflux.

[0013] Preferably, the adjustment assembly includes a connecting arm, a pin and a driving member, wherein the connecting arm is arranged at the first end of the guide block and is rotatably connected to the side wall of the volute tongue through the pin, the guide block is rotatably arranged above the opening and can rotate under the drive of the driving member, and the second end of the guide block is a rotating free end. The volute tongue is provided with a receiving cavity arranged close to the air outlet side, and the driving member is a motor arranged in the receiving cavity, and the output shaft of the motor is connected to the pin. The above structure is adopted to facilitate driving the guide block to move, thereby realizing the opening or closing of the opening.

[0014] As a further improvement, a second baffle is provided on the outside of the first baffle, and the second baffle, the side wall of the volute tongue and the first baffle together enclose a closed first cavity, and a first through hole is provided on the first baffle for airflow to enter the first cavity from the guide cavity. Preferably, the thickness of the first baffle is 1.5 to 2 mm, and the diameter of the first through hole is 1 to 1.8 mm. With such a structure, the secondary removal of the reflux gas can be achieved, and the eddy current can be further reduced. At the same time, the first baffle, the second baffle and the first cavity between the two can form a sound-absorbing resonance structure, thereby suppressing the turbulent noise there and achieving a noise reduction effect.

[0015] Further improvement, a third baffle arranged parallel to the second baffle is provided in the first cavity, and the third baffle, the second baffle and the inner wall of the volute tongue together enclose the second cavity, and the third baffle is provided with a second through hole for airflow from the first cavity into the second cavity. The thickness of the third baffle is 0.75-1 mm, and the diameter of the second through hole is 0.5-0.75 mm. Although the first baffle, the second baffle and the first cavity between the two form a sound-absorbing resonance structure, they may also generate nonlinear acoustic resistance, thereby forming secondary noise. The third baffle and the second cavity are provided to suppress a wider noise band, better offset the original noise, and have a higher sound absorption coefficient, ultimately achieving the reduction of noise at the volute tongue under large flow conditions, the elimination of vortices, and the improvement of the total pressure and efficiency of the fan.

[0016] In the above schemes, the inner wall of the volute tongue includes a first arc surface segment, a second arc surface segment and a first plane segment. The first arc surface segment is arranged close to the impeller of the centrifugal fan and its lower surface constitutes the first guide surface of the centrifugal fan. The first plane segment is arranged on the air outlet side of the volute and its inner surface constitutes the second guide surface of the centrifugal fan. The second arc surface segment is connected between the first arc surface segment and the first plane segment.

[0017] For the convenience of connection, the upper edge of the volute tongue is connected to the upper edges of the front cover plate and the rear cover plate, and the lower edge of the volute tongue is connected to the first end edge of the volute ring wall and is sealed by silicone.

[0018] Preferably, the first baffle includes a second plane segment and a third arc segment, the second plane segment is arranged close to the first plane segment, the upper end of the third arc segment is connected with the lower end of the second plane segment, the third arc segment is arched toward the second arc segment and the lower end is connected with the upper surface of the first arc segment. The width of the guide channel formed between the first plane segment and the second plane segment gradually decreases from bottom to top. The above structure enables the guide cavity and the narrow and long guide channel to form a structure roughly in the shape of 6, thereby playing a good role in guiding and breaking vortices.

[0019] Preferably, the lower surface of the guide block is formed as a first curved surface that arches downward, and correspondingly, the two side walls of the opening are formed as matching surfaces that can match the first curved surface. The upper surface of the guide block is formed with a second curved surface that arches upward, the curvature of the second curved surface is greater than the curvature of the first curved surface, and the connection between the first curved surface and the second curved surface is smoothly transitioned. The above structure can reduce the resistance of the guide block to the wind flow.

[0020] Compared with the prior art, the advantages of the present invention are: the present invention divides the volute ring wall into a first ring wall and a second ring wall, and the first ring wall and the second ring wall divide the volute cavity into an outer cavity and an inner cavity. During the use of the centrifugal fan, part of the airflow is discharged from the air outlet through the outer cavity, and the other part of the airflow circulates through the inner cavity to the air guide port at the top of the inner cavity and is discharged through the air outlet. The setting of the above-mentioned second ring wall plays a good diversion role, thereby reducing gas reflux and reducing eddy current problems, thereby reducing fan noise and improving fan efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of an embodiment of the present invention (equipped with an impeller);

[0022] Figure 2 for Figure 1 A cross-sectional view of

[0023] Figure 3 It is a schematic diagram of the structure of the snail tongue in an embodiment of the present invention;

[0024] Figure 4It is a schematic diagram of the assembly structure of the guide block, the connecting arm and the driving member in an embodiment of the present invention;

[0025] Figure 5 is a cross-sectional view of a snail tongue in an embodiment of the present invention;

[0026] Figure 6 for Figure 5 A schematic diagram of the structure of the hidden guide block;

[0027] Figure 7 for Figure 2 Schematic diagram of the enlarged structure of part A. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings.

[0029] like Figures 1 to 7 As shown, the volute structure of the centrifugal fan of this embodiment includes a volute tongue 1, a front cover plate 2, a rear cover plate 3 and a volute ring wall 4. The front cover plate 2 and the rear cover plate 3 are arranged in a front-to-back spacing, and the volute ring wall 4 is connected between the front cover plate 2 and the rear cover plate 3. The volute tongue 1 is arranged on the first end of the volute ring wall 4, and a side wall of the volute tongue 1 and the side wall opposite to the volute ring wall 4 and the front cover plate 2 and the rear cover plate 3 together enclose an air outlet 40.

[0030] In this embodiment, the volute annular wall 4 includes a first annular wall 41 and a second annular wall 42. The first annular wall 41 is connected between the front cover plate 2 and the rear cover plate 3 and encloses the volute cavity with the front cover plate 2 and the rear cover plate 3. The second annular wall 42 is arranged in the volute cavity 40 and divides the volute cavity 40 into an outer cavity 401 and an inner cavity 402. The rear edge of the second annular wall 42 is connected to the rear cover plate 3. The front edge of the second annular wall 42 gradually tilts backward from the upper part to connect the outer cavity 401 and the inner cavity 402. The second annular wall 42 is provided with an air guide port 421 arranged near the air outlet 40 in the axial direction. In this embodiment, the rear edge of the second annular wall 42 is connected to the front side of the rear cover plate 3, the top of the front edge of the second annular wall 42 is connected to the rear side of the front cover plate 2, and the minimum width of the second annular wall 42 in the axial direction is 0.25 to 0.5 times the maximum width. An air inlet 21 is provided in the central portion of the front cover plate 2, and the second annular wall 42 is arranged concentrically with the air inlet 21 to achieve a better flow diversion effect.

[0031] The bottom of the volute tongue 1 of this embodiment is provided with an opening 1111 corresponding to the air guide port 421, and a flow guide structure capable of guiding the airflow in the volute inner cavity 402 to the volute air outlet 40 is arranged above the opening 1111. The structure directly transports the airflow from the inner cavity 402 formed by the second annular wall 42 to the air outlet 40, which can effectively break the vortex and reduce the gas reflux. The air guide port 421 penetrates along the axial direction of the second annular wall 42 so that the second annular wall 42 is formed into an open-loop structure, the first end of the second annular wall 42 is connected to the edge of one side of the opening 1111 of the volute tongue 1 away from the air outlet 40, and a gap 420 is formed between the second end of the second annular wall 42 and the lower surface of the volute tongue 1 close to the air outlet 40. When the fan flow is small, the flow guide structure can be in a closed state, and part of the airflow diverted from the inner cavity 402 formed by the second annular wall 42 is discharged from the above-mentioned gap 420 and discharged through the air outlet 40.

[0032] The volute tongue 1 of this embodiment has a volute tongue inner wall 11, which includes a first arc surface segment 111, a second arc surface segment 112 and a first plane segment 113. The first arc surface segment 111 is arranged close to the impeller of the centrifugal fan and its lower surface constitutes the first guide surface of the centrifugal fan. The first plane segment 113 is arranged on the air outlet 40 side of the volute and its inner surface constitutes the second guide surface of the centrifugal fan. The second arc surface segment 112 is connected between the first arc surface segment 111 and the first plane segment 113. The upper edge of the volute tongue 1 of this embodiment is connected to the upper edges of the front cover plate 2 and the rear cover plate 3 by screws, and the lower edge of the volute tongue 1 is connected to the first end edge of the volute ring wall 4 by screw connection and sealed by silicone.

[0033] In this embodiment, a volute tongue side plate 12 is respectively provided on both sides of the volute tongue 1, and the volute tongue side plate 12 closes both sides of the volute tongue 1 to form a cavity 10. A first baffle 13 extending along the outer wall of the volute tongue into the cavity 10 is provided on the outer side of the volute tongue 1 corresponding to the opening of the cavity 10. The first baffle 13 includes a second plane section 131 and a third arc surface section 132. The second plane section 131 is arranged close to the first plane section 113, and the upper end of the third arc surface section 132 is connected with the lower end of the second plane section 131. The third arc surface section 132 is arched toward the second arc surface section 112 and the lower end is connected with the upper surface of the first arc surface section 112. A narrow and long guide channel 14 is formed between the second plane section 131 of the first baffle 13 and the first plane section 11 of the inner wall 11 of the volute tongue, and the width of the guide channel 14 gradually decreases from bottom to top. The lower part of the first baffle 13 and the inner wall of the cavity 10 enclose a guide cavity 15, and an opening 1111 is provided on the first arc surface section 111 so that airflow can enter the guide cavity 15. The above-mentioned guide channel 14 and the guide cavity 15 together constitute a guide structure. A guide block 100 is also provided in the guide cavity 15, which can cover the opening 1111 or open the opening 1111. The lower surface of the guide block 100 is formed as a first arc surface 101 that arches downward, and correspondingly, the two side walls of the opening 1111 are formed as matching surfaces 1112 that can match the first arc surface 101. The upper surface of the guide block 100 is formed with a second arc surface 102 that arches upward, and the curvature of the second arc surface 102 is greater than the curvature of the first arc surface 101, and the connection between the first arc surface 101 and the second arc surface 102 is smoothly transitioned. This structure can reduce the resistance of the guide block 100 to the wind flow. The flow guiding cavity 15 and the narrow and long flow guiding channel 14 of this embodiment together form a structure roughly in the shape of 6, thereby playing a good role in guiding and breaking vortices.

[0034] A sensor 422 capable of detecting the amount of air is disposed on the inner wall of the second annular wall 42, and an adjustment component 16 capable of adjusting the opening and closing of the guide block 100 relative to the opening 1111 according to the amount of air is disposed on the volute tongue 1. The adjustment component 16 includes a connecting arm 161, a pin 162, and a driving member 163. The connecting arm 161 is two and is respectively connected to both sides of the first end of the guide block 100. The other end of the connecting arm 161 is rotatably connected to the volute tongue side plate 12 through the pin 162, and the connection is arranged near the second arc surface section 112. The guide block 100 is rotatably disposed above the opening 1111 and can rotate under the drive of the driving member 163. The second end of the guide block 100 is a rotating free end. The volute 1 is provided with a receiving chamber 19 arranged near the air outlet side. The driving member 163 is a motor arranged in the receiving chamber 19. The output shaft of the motor is connected to the pin shaft 162 to drive the guide block 100 to move, thereby realizing the opening or closing of the opening 1111.

[0035] In this embodiment, a second baffle 17 is arranged outside the first baffle 13, the upper end of the second baffle 17 is connected to the air outlet end of the first plane section 113, and the lower end of the second baffle 17 is connected to the outer end of the first plane section 113, so as to enclose a closed first cavity 170 together with the volute tongue side plate 12 and the first baffle 13, and a first through hole 130 is opened on the first baffle 13 for airflow from the guide cavity 15 into the first cavity 170. The thickness of the first baffle 13 is 1.5 to 2 mm, and the diameter of the first through hole 130 is 1 to 1.8 mm. A third baffle 18 arranged parallel to the second baffle 17 is arranged in the first cavity 170, and the third baffle 18, the second baffle 17, and the inner wall of the volute tongue together enclose a second cavity 180, and a second through hole 181 is opened on the third baffle 18 for airflow from the first cavity 17 into the second cavity 18. The thickness of the third baffle 18 is 0.75-1 mm, and the diameter of the second through hole 181 is 0.5-0.75 mm. Although the first baffle 13, the second baffle 17 and the first cavity 170 therebetween form a sound-absorbing resonance structure, they may also generate nonlinear acoustic resistance, thereby forming secondary noise. The third baffle 18 and the second cavity 180 can suppress a wider noise band, better offset the original noise, and have a higher sound absorption coefficient, ultimately achieving the reduction of noise at the volute tongue under large flow conditions, the elimination of vortices, and the improvement of the fan's total pressure and efficiency.

[0036] When the volute structure of the present embodiment is used, when the fan flow rate is small, the noise is small, the guide block 100 closes the opening 1111, and part of the air flow is discharged from the air outlet 40 through the outer cavity 401, and the other part of the air flow is circulated through the inner cavity 402 to the air guide port 421 and the gap 420 at the top of the inner cavity 402 and is discharged through the air outlet 40; when the fan flow rate is large, the backflow of gas at the volute tongue 1 increases, and when the sensor 422 detects that the air volume reaches a certain value, the controller controls the driving member 163 to drive the guide block 100 to rotate and open the opening 1111. At this time, part of the gas enters the guide cavity 15 through the air guide port 421 and the opening 1111, and part of the gas entering the guide cavity 15 directly passes through the narrow and long guide channel 14 is accelerated and discharged from the air outlet 40, and the other part passes through the first through hole 130 on the first baffle 13 into the first cavity 170, and then passes through the second through hole 181 on the third baffle 18 into the second cavity 180 and is discharged from the guide channel 14 after circulation, thereby realizing the secondary discharge of the reflux gas, reducing the gas reflux, and eliminating the vortex problem, thereby reducing the fan noise and improving the fan efficiency; and the sound-absorbing resonance structure formed by the first baffle, the second baffle, and the third baffle can suppress turbulent noise, suppress a wider noise frequency band, better offset the original noise, and have a higher sound absorption coefficient, ultimately achieving the reduction of noise at the volute tongue under large flow conditions, the elimination of vortices, and the improvement of the total pressure and efficiency of the fan.

Claims

1. A volute structure of a centrifugal fan, comprising a volute tongue (1), a front cover plate (2), a rear cover plate (3) and a volute ring wall (4), wherein the front cover plate (2) and the rear cover plate (3) are arranged with a front-to-back spacing, the volute ring wall (4) is arranged between the front cover plate (2) and the rear cover plate (3), an air inlet (21) is opened at the central portion of the front cover plate (2), the volute tongue (1) is arranged on a first end of the volute ring wall (4) and is arranged close to an air outlet (40) of the volute, and is characterized in that: The volute annular wall (4) comprises a first annular wall (41) and a second annular wall (42); the first annular wall (41) is connected between the front cover plate (2) and the rear cover plate (3) and encloses a volute cavity together with the front cover plate (2) and the rear cover plate (3); the second annular wall (42) is arranged in the volute cavity and divides the volute cavity into an outer cavity (401) and an inner cavity (402); the rear edge of the second annular wall (42) is connected to the rear cover plate (3); the front side edge of the second annular wall (42) is at least gradually inclined backward from the middle part to connect the outer cavity (401) and the inner cavity (402); the second annular wall (42) is provided with an air guide port (421) arranged close to the air outlet (40) along the axial direction; The bottom of the volute tongue (1) is provided with an opening (1111) corresponding to the air guide port (421), and a flow guide structure capable of guiding the airflow in the volute inner cavity (402) to the volute air outlet (40) is arranged above the opening (1111); the volute tongue (1) has a volute tongue inner wall (11), and both sides of the volute tongue (1) are closed to form a cavity (10); a first baffle (13) is arranged on the outer side of the volute tongue (1) and extends into the cavity (10) along the outer wall of the volute tongue (1), and a flow guide channel (14) is formed between the upper part of the first baffle (13) and the corresponding volute tongue inner wall (11); a flow guide cavity (15) is enclosed between the lower part of the first baffle (13) and the inner wall of the cavity (10); the opening is arranged at the bottom of the flow guide cavity (15), and the flow guide channel (14) and the flow guide cavity (15) together constitute the flow guide structure; A second baffle (17) is arranged outside the first baffle (13); the second baffle (17) and the side wall of the volute tongue and the first baffle (13) together enclose a closed first cavity (170); the first baffle (13) is provided with a first through hole (130) for airflow from the guide cavity (15) into the first cavity (170); a third baffle (18) arranged parallel to the second baffle (17) is arranged inside the first cavity (170); the third baffle (18) and the second baffle (17) and the inner wall of the volute tongue together enclose a second cavity (180); the third baffle (18) is provided with a second through hole (181) for airflow from the first cavity (170) into the second cavity (180).

2. The volute structure of the centrifugal fan according to claim 1, characterized in that: The rear edge of the second annular wall (42) is connected to the front side of the rear cover plate (3), the top of the front edge of the second annular wall (42) is connected to the rear side of the front cover plate (2), and the minimum axial width of the second annular wall (42) is 0.25 to 0.5 times the maximum width.

3. The volute structure of the centrifugal fan according to claim 1, characterized in that: The second annular wall (42) is arranged concentrically with the air inlet (21).

4. The volute structure of the centrifugal fan according to claim 1, characterized in that: The air guide port (421) penetrates the second annular wall (42) axially so that the second annular wall (42) forms an open-loop structure; the first end of the second annular wall (42) is connected to an edge of a side of the volute tongue opening (1111) away from the air outlet (40); and a gap (420) is formed between the second end of the second annular wall (42) and the lower surface of the volute tongue (1) close to the air outlet (40).

5. The volute structure of the centrifugal fan according to claim 1, characterized in that: The diversion cavity (15) is also provided with a diversion block (100) capable of covering the opening (1111) or opening the opening (1111).

6. The volute structure of the centrifugal fan according to claim 5, characterized in that: A sensor (422) capable of detecting the amount of air flow is provided on the inner wall of the second annular wall (42), and an adjustment component (16) capable of adjusting the opening or closing of the guide block (100) relative to the opening (1111) according to the amount of air flow is provided on the volute tongue (1).

7. The volute structure of the centrifugal fan according to claim 6, characterized in that: The adjustment assembly (16) comprises a connecting arm (161), a pin shaft (162) and a driving member (163); the connecting arm (161) is arranged at the first end of the guide block (100) and is rotatably connected to the side wall of the volute tongue (1) via the pin shaft (162); the guide block (100) is rotatably arranged above the opening (1111) and can rotate under the drive of the driving member (163); the second end of the guide block (100) is a rotating free end.

8. The volute structure of the centrifugal fan according to claim 7, characterized in that: The volute tongue (1) is provided with a receiving chamber (19) arranged close to the air outlet side, and the driving member (163) is a motor arranged in the receiving chamber (19), and the output shaft of the motor is connected to the pin shaft (162).

9. The volute structure of a centrifugal fan according to claim 1, characterized in that: The thickness of the first baffle (13) is 1.5 to 2 mm, and the diameter of the first through hole (130) is 1 to 1.8 mm.

10. The volute structure of a centrifugal fan according to claim 1, characterized in that: The thickness of the third baffle (18) is 0.75 to 1 mm, and the diameter of the second through hole (181) is 0.5 to 0.75 mm.

11. The volute structure of a centrifugal fan according to any one of claims 1 to 10, characterized in that: The inner wall (11) of the volute tongue comprises a first arc surface segment (111), a second arc surface segment (112) and a first plane segment (113); the first arc surface segment (111) is arranged close to the impeller of the centrifugal fan and its lower surface constitutes a first flow guide surface of the centrifugal fan; the first plane segment (113) is arranged on the air outlet (40) side of the volute and its inner surface constitutes a second flow guide surface of the centrifugal fan; the second arc surface segment (112) is connected between the first arc surface segment (111) and the first plane segment (113).

12. The volute structure of a centrifugal fan according to any one of claims 1 to 10, characterized in that: The upper edge of the volute tongue (1) is connected to the upper edges of the front cover plate (2) and the rear cover plate (3), and the lower edge of the volute tongue (1) is connected to the first end edge of the volute ring wall (4) and is sealed by silicone.

13. The volute structure of the centrifugal fan according to claim 11, characterized in that: The first baffle (13) comprises a second plane section (131) and a third arc surface section (132); the second plane section (131) is arranged close to the first plane section (113); the upper end of the third arc surface section (132) is connected to the lower end of the second plane section (131); the third arc surface section (132) is arched toward the second arc surface section (112) and the lower end is connected to the upper surface of the first arc surface section (111).

14. The volute structure of the centrifugal fan according to claim 13, characterized in that: The width of the guide channel (14) formed between the first plane section (113) and the second plane section (131) gradually decreases from bottom to top.

15. The volute structure of a centrifugal fan according to any one of claims 5 to 8, characterized in that: The lower surface of the guide block (100) is formed as a first curved surface (101) that arches downward, and correspondingly, the two side walls of the opening (1111) are formed as matching surfaces (1112) that can match the first curved surface (101).

16. The volute structure of the centrifugal fan according to claim 15, characterized in that: The upper surface of the guide block (100) is formed with a second curved surface (102) that arches upwards, the curvature of the second curved surface (102) is greater than the curvature of the first curved surface (101), and the connection between the first curved surface (101) and the second curved surface (102) is smoothly transitioned.

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