CN216077724U - Volute for centrifugal fan and centrifugal fan applying volute - Google Patents

Abstract

The utility model relates to a volute for a centrifugal fan and the centrifugal fan using the same, comprising: the volute comprises a volute body and a volute body, wherein the volute body comprises a rear cover plate, a front cover plate and a ring wall, and the ring wall is arranged between the front cover plate and the rear cover plate and is provided with a first end part and a second end part which are opposite in the length direction; the volute tongue piece is rotatably connected to the first end part of the annular wall and defines an air outlet with an adjustable expansion angle together with the rear cover plate, the front cover plate and the second end part of the annular wall; the volute tongue piece is provided with a first connecting end and a second connecting end in the length direction, the first connecting end of the volute tongue piece is rotatably connected to the first end of the annular wall, and the second connecting end of the volute tongue piece is constrained on at least one of the front cover plate and the rear cover plate in a sliding mode along the plane where the air outlet is located in a manner of being capable of stretching relative to the first connecting end of the volute tongue piece. In the rotation process of the volute tongue piece, the end part of the volute tongue piece cannot be exposed out of the plane of the air outlet of the volute, so that the problem of interference with a pipe fitting connected to the air outlet cannot occur.

Description

Volute for centrifugal fan and centrifugal fan applying volute

Technical Field

The utility model relates to the technical field of centrifugal fans, in particular to a volute for a centrifugal fan and a centrifugal fan applying the volute.

Background

Centrifugal fans, especially multi-blade centrifugal fans, are widely used in air conditioners, range hoods, air fresheners, ventilators and other household appliances because of their advantages of compact structure, high pressure coefficient, large flow coefficient, low noise and the like. Once the multi-wing centrifugal fan is designed, manufactured and processed, all structural dimension parameters of the multi-wing centrifugal fan are uniquely determined. However, in the actual use process of the fan, the working air volume of the fan can be adjusted according to specific requirements, and in this case, the outlet type uniquely determined by the original fan may become a negative factor. Moreover, due to the diffusion effect of the multi-wing centrifugal fan, the airflow at the outlet of the fan is in an expansion trend after being thrown out by the impeller, so that when the outlet of the fan is designed, the outlet at one side of the volute tongue is expanded outwards by a certain angle, and the obstruction is avoided. However, when the working air volume of the fan is reduced and the airflow thrown out by the impeller is not enough to fill the whole outlet, the outlet area on the volute tongue side can generate large vortex due to the existence of strong speed difference to bring vortex noise, and simultaneously, the outflow of the air in the fan can be further blocked, so that the overall noise of the fan is increased.

Therefore, a centrifugal fan structure with an adjustable expansion angle of the volute tongue side outlet appears, and as disclosed in the utility model patent in china with application number cn201820384681.x (publication number CN208154761U), an air conditioner is disclosed, which comprises: the volute component comprises a volute body, a volute tongue and a diffusion section, the volute tongue is connected with the lower surface of the outlet end of the volute body and can rotate relative to the volute body, the diffusion section is connected with the front end of the volute tongue so as to be driven by the volute tongue to synchronously rotate, and the diffusion section is provided with an air guide section extending downwards. The wind wheel is arranged in the wind guide air duct, and at least one part of the indoor heat exchanger is arranged in the shell and is positioned between the air inlet and the inlet end of the volute main body.

However, the volute for the centrifugal fan in the above patent still has certain disadvantages, firstly, after the angle of the volute tongue in the patent is changed, the air outlet plane of the volute is changed, that is, the end part of the movable volute tongue can be exposed out of the plane of the original air outlet, and the fixing of the air outlet plane cannot be ensured, which is applicable to a completely open air outlet (such as an air conditioner), and is inapplicable to the situation that the rear end needs to be connected with components such as a pipeline, and if the volute tongue structure is applied to a range hood, the exposed volute tongue structure can form an interference problem with a smoke exhaust pipe. Secondly, after the volute tongue angle in the above patent is changed, the air outlet plane of the volute casing is changed, and the direction of the air flow cannot be effectively controlled, for example, the wall plate on the volute tongue side is shortened, because of no wall surface flow guide, the outlet air can be more easily expanded to the volute tongue side, and additional air flow separation is caused, for example, the wall plate on the volute tongue side is lengthened, the outlet air should begin to be expanded at the original air outlet, but because of the constraint of an extra section of wall surface, the outlet air flow can be extruded, and resistance is formed, and the optimal flow state cannot be achieved.

SUMMERY OF THE UTILITY MODEL

The first technical problem to be solved by the utility model is to provide a volute for a centrifugal fan, aiming at the current situation of the prior art, wherein the length of a volute tongue can be telescopically adjusted in the rotating process, so that the problem of interference caused by the fact that the end part of the volute tongue is exposed out of the plane where an air outlet of the volute is located is avoided.

The second technical problem to be solved by the present invention is to provide a volute for a centrifugal fan, in which the length of the volute tongue can be adjusted in a telescopic manner during rotation, so as to prevent the plane where the air outlet is located from changing.

The third technical problem to be solved by the present invention is to provide a centrifugal fan using the above volute, aiming at the current situation of the prior art.

The technical scheme adopted by the utility model for solving the first technical problem is as follows: a volute for a centrifugal fan, comprising:

the volute comprises a volute body and a volute body, wherein the volute body comprises a rear cover plate, a front cover plate and a ring wall, the front cover plate and the rear cover plate are arranged oppositely, and the ring wall is arranged between the front cover plate and the rear cover plate and is provided with a first end part and a second end part which are opposite in the length direction;

the volute tongue piece is rotatably connected to the first end part of the annular wall and defines an air outlet with an adjustable expansion angle together with the rear cover plate, the front cover plate and the second end part of the annular wall;

the volute tongue piece is of a plate-shaped structure with the length capable of being adjusted in a telescopic mode, the plate-shaped structure is provided with a first connecting end and a second connecting end in the length direction, the first connecting end of the volute tongue piece is rotatably connected to the first end of the annular wall, and the second connecting end of the volute tongue piece is constrained on at least one of the front cover plate and the rear cover plate in a sliding mode along the plane where the air outlet is located.

The volute tongue piece can be a telescopic integral part or a split part which can move relative to the volute tongue piece, and in order to save cost, the volute tongue piece comprises a first plate and a second plate, the first plate is connected with the first end of the annular wall, the second plate is connected with at least one of the front cover plate and the rear cover plate, and the first plate and the second plate are constrained together in a relative sliding mode. Of course, the expansion adjustment of the whole volute tongue piece can be realized by three or more than three plate bodies in a sliding fit mode.

In a preferred embodiment, the first plate and the second plate are connected by magnetic attraction. Through the mode of magnetism, simplified the overall structure of snail tongue spare, reduced manufacturing cost.

In another preferred embodiment, one of the first plate and the second plate has a first bar-shaped sliding slot arranged along the extending direction of the first plate, and the other plate has a sliding block slidably constrained in the first bar-shaped sliding slot.

In another preferred embodiment, the first plate and the second plate are slidably connected by a sliding rail.

In order to ensure the stability of the relative movement between the first plate and the second plate, the slide rail is a ball slide rail and is arranged between two opposite planes of the first plate and the second plate.

In order to connect the second plate with the rear cover plate and the front cover plate and ensure the stable movement of the second plate, the two opposite side surfaces of the front cover plate and the rear cover plate, which are adjacent to the air outlet, are provided with second strip-shaped chutes, and the two transverse sides of the second connecting end of the worm-tongue piece are provided with convex columns which are respectively constrained in the corresponding second strip-shaped chutes in a sliding manner.

In order to avoid the influence of the volute tongue piece on the effective air outlet area of the volute air outlet during the rotation adjustment, the volute tongue piece has a first limit state close to the second end of the annular wall and a second limit state far away from the second end of the annular wall in the rotation process relative to the volute main body, and the plane of the volute tongue piece is basically parallel to the plane of the second end of the annular wall when the volute is in the first limit state.

In order to drive the volute tongue piece to rotate, the volute further comprises a driving motor arranged at the first end part of the annular wall, the volute is provided with an axis, an output shaft of the driving motor is parallel to the axis of the volute, and the output shaft of the driving motor is connected with the first connecting end of the volute tongue piece, so that the volute tongue piece is driven to rotate around the output shaft of the driving motor.

The centrifugal fan with the volute is used for solving the second technical problem.

Compared with the prior art, the utility model has the advantages that: the length of the volute tongue piece of the volute can be adjusted in a telescopic mode in the rotating process, wherein the end portion of the volute tongue piece cannot be exposed out of the plane where the air outlet of the volute is located in the rotating process of the volute tongue piece, and therefore the volute tongue piece cannot interfere with a pipe fitting connected to the air outlet. On the other hand, the length of the volute tongue piece can be adjusted in a telescopic mode, so that the plane where the air outlet of the volute is located cannot change, namely in the rotation process of the volute tongue piece, the problems that extra airflow separation is caused due to the fact that the wall plate on the volute tongue side is shortened, resistance is formed due to the fact that the wall plate on the volute tongue side is lengthened to extrude outlet airflow and the like cannot occur, and the fact that the airflow at the air outlet of the volute can still reach the optimal flowing state after the angle of the volute tongue piece is adjusted is guaranteed.

Drawings

Fig. 1 is a schematic perspective view of a centrifugal fan according to an embodiment of the present invention;

FIG. 2 is a schematic perspective view of a centrifugal fan according to an embodiment of the present invention (the volute tongue is rotated to another angular position);

FIG. 3 is a cross-sectional view of a centrifugal fan of an embodiment of the present invention taken perpendicular to the axis of the volute;

FIG. 4 is a schematic structural diagram of a volute tongue of a centrifugal fan according to an embodiment of the present invention in different rotation angles;

FIG. 5 is a schematic perspective view of the tongue member of FIG. 1 without the tongue member (the driving motor is not shown);

FIG. 6 is a schematic perspective view of FIG. 5 flipped to another angular position;

FIG. 7 is a perspective view of a tongue of the present invention;

FIG. 8 is a perspective view of another angle of the tongue of the present invention;

FIG. 9 is a perspective view of another angular position of the tongue member according to the embodiment of the present invention;

FIG. 10 is a schematic view of the structure of FIG. 3 with the tongue omitted;

fig. 11 is a schematic perspective view of a tongue of a volute of embodiment 2 of the utility model;

FIG. 12 is an exploded view of FIG. 11;

fig. 13 is a schematic perspective view of a tongue of a volute of embodiment 3 of the utility model;

fig. 14 is an exploded view of fig. 13.

Detailed Description

The utility model is described in further detail below with reference to the accompanying examples.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and to simplify the description, but are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and that the directional terms are used for purposes of illustration and are not to be construed as limiting, for example, because the disclosed embodiments of the present invention may be oriented in different directions, "lower" is not necessarily limited to a direction opposite to or coincident with the direction of gravity. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

Example 1

Referring to fig. 1-10, a centrifugal fan includes a volute and an impeller 30 disposed in the volute. The volute comprises a volute body and a volute tongue piece 20, wherein the volute body comprises a rear cover plate 11, a front cover plate 12 and a ring wall 13, the front cover plate 12 is arranged opposite to the rear cover plate 11, the ring wall 13 is arranged between the front cover plate 12 and the rear cover plate 11, and specifically, the ring wall 13 has a first end 131 and a second end 132 which are opposite in the length direction. The volute tongue 20 is rotatably connected to the first end 131 of the annular wall 13 and defines, together with the rear cover 11, the front cover 12 and the second end 132 of the annular wall 13, the outlet mouth 15 whose divergence angle is adjustable. In addition, the front cover plate 12 of the volute body is provided with an air inlet which is opposite to the impeller 30, when the centrifugal fan operates, external air flow enters from the air inlet along the axis of the impeller 30, is radially thrown out through the centrifugal action of the impeller 30 and is discharged from the air outlet 15. The above-mentioned spiral casing structure with the rotatable adjustment of the spiral tongue piece 20 is the prior art and will not be described herein.

When the working air quantity of the centrifugal fan is larger, the volute tongue piece 20 can be correspondingly adjusted in a rotating mode, so that the outlet on the volute tongue side is expanded to be in a larger angle state. When the working air volume of the centrifugal fan is small, the expansion angle of the volute tongue side outlet is correspondingly adjusted to be in a small state. In order to ensure that the plane of the air outlet 15 remains unchanged before and after the rotation adjustment of the tongue 20, the tongue 20 of the present embodiment is plate-shaped and has a length adjustable in a telescopic manner, and the tongue has a first connection end 21 and a second connection end 22 in the length direction, specifically, the first connection end 21 of the tongue 20 is rotatably connected to the first end 131 of the annular wall 13, and correspondingly, the second connection end 22 of the tongue 20 is slidably constrained on at least one of the front cover plate 12 and the rear cover plate 11 along the plane of the air outlet 15 in a telescopic manner with respect to the first connection end 21 of the tongue 20, as shown in fig. 4.

The volute tongue 20 of the present embodiment comprises a first plate 23, a second plate 24 and a driving motor 28, wherein the first plate 23 is rotatably connected with the first end 131 of the annular wall 13, the second plate 24 is connected with at least one of the front cover plate 12 and the rear cover plate 11, and the first plate 23 and the second plate 24 are constrained together in a relatively sliding manner. Specifically, in order to simplify the overall structure of the tongue piece 20, the first plate 23 and the second plate 24 are connected in a magnetic attraction manner, wherein the first plate 23 and the second plate 24 both have magnetic attraction surfaces, the magnetic attraction surfaces of the first plate 23 and the second plate 24 can be attached together, in the rotation adjustment process of the first plate 23, the first plate 23 and the second plate 24 can slide relative to each other along the magnetic attraction surfaces, and the magnetic attraction force can keep the connection between the first plate 23 and the second plate from loosening, which is shown in detail in fig. 7-9.

Referring to fig. 3 and 10, the first end 131 of the annular wall 13 of the present embodiment has a first arc-shaped wall 14 with a C-shaped cross section and a notch facing the air outlet 15, that is, the first arc-shaped wall 14 extends in a curved manner toward the position of the air outlet 15, a mounting cavity 143 is defined inside the first arc-shaped wall 14, and the outer wall surface of the first arc-shaped wall 14 forms a flow guide surface for guiding the air flow toward the air outlet 15. Correspondingly, the end of the first plate 23 of the volute tongue 20 is provided with a rotating connecting part 210, and at least part of the rotating connecting part 210 is accommodated in the accommodating cavity 143 of the first arc-shaped wall 14 and is provided with an arc-shaped wall surface which can be always attached to the inner surface of the first arc-shaped wall 14 in the rotating process. The "cross-section" of the first arcuate wall 14 described above refers to a cross-section of the first arcuate wall 14 in a plane perpendicular to the axis O of the volute.

With continued reference to fig. 7-9, the rotating connection portion 210 of the first plate 23 of the volute tongue 20 comprises a second arc-shaped wall 211 and a connecting column 212, wherein the second arc-shaped wall 211 has a C-shaped cross section, and the second arc-shaped wall 211 has a shape substantially identical to the shape of the first arc-shaped wall 14, and is a circular arc-shaped wall, and the two arc-shaped walls are coaxially arranged. After the rotation connecting portion 210 is assembled in place, the outer wall surface of the second arc-shaped wall 211 and the inner wall surface of the first arc-shaped wall 14 are attached to each other, so that the arc-shaped wall surface of the rotation connecting portion 210 is formed. The connecting column 212 is located inside the second arc-shaped wall 211 and close to the side of the front cover plate 12, and specifically, the connecting column 212 and the second arc-shaped wall 211 are a single piece. One end of the connecting column 212 has a limiting hole 213, and the other end has a positioning hole 214. The "cross section" of the second arc-shaped wall 211 described above refers to a section of the first arc-shaped wall 211 on a plane perpendicular to the axis O of the volute.

Referring to fig. 5 and 6, the driving motor 28 is also located inside the second arc-shaped wall 211, and is specifically arranged side by side with the connecting column 212 in the axial direction of the second arc-shaped wall 211. The output shaft of the driving motor 28 is coaxial with the second arc-shaped wall 211 and is inserted into the limiting hole 213 of the connecting column 212 so as to drive the volute tongue piece 20 to rotate by taking the output shaft of the driving motor 28 as a rotation center. Wherein the volute has an axis, and the axis of the output shaft of the driving motor 28 is parallel to the axis of the volute. In addition, the cross section of the output shaft of the driving motor 28 may be a non-circular structure, and the positioning hole 214 is a structure matched with the non-circular structure, so that the positioning hole and the positioning hole are limited in the circumferential direction.

The first curved wall 14 has a first port 141 and a second port 142 that are laterally opposed. The rear cover 11 has a first extension 110 covering the first port 141, and the front cover 12 has a second extension 120 covering the second port 142, wherein the driving motor 28 is fixedly connected to an inner wall of the first extension 110. The inner wall of the second extending portion 120 has a positioning post 111, and the positioning post 111 can be inserted into the positioning hole 214 of the connecting post 212 for rotation fit. The "lengthwise direction" of the first arcuate wall 14 of the present embodiment refers to a direction parallel to the axis O of the volute.

Referring to fig. 5 and 7, the two opposite side surfaces of the front cover plate 12 and the rear cover plate 11 of the present embodiment adjacent to the air outlet 15 are respectively provided with a second strip-shaped chute 16, and the second strip-shaped chute 16 extends along the edge of the front cover plate 12 or the rear cover plate 11 to ensure that the second strip-shaped chute is parallel to the plane where the air outlet 15 is located. The second connection end 22 of the tongue 20 has bosses 241 at both lateral sides, that is, the bosses 241 are provided at both lateral sides of the end of the second plate 24 far from the first plate 23. The two protruding columns 241 are slidably constrained in the corresponding second strip-shaped sliding grooves 16 respectively. The outer diameter of the convex column 241 is matched with the width of the second strip-shaped sliding groove 16, so that stable sliding of the convex column and the second strip-shaped sliding groove is ensured.

In order to avoid interference with the rotation of the volute tongue member 20 due to an excessively large central angle corresponding to the arc length of the cross section of the first arc-shaped wall 14, limit the rotation angle of the volute tongue member 20, and avoid that the gap opening between the first arc-shaped wall 14 and the rotation connection portion 210 of the volute tongue member 20 cannot face away from the incoming flow better due to an excessively small central angle corresponding to the arc length of the cross section of the first arc-shaped wall 14, a tangent line a of the cross section of the first arc-shaped wall 14 at one end adjacent to the air outlet 15 is parallel to a plane where the second end portion 132 of the ring wall 13 is located, so that the gap opening between the first arc-shaped wall 14 and the rotation connection portion 210 of the volute tongue member 20 faces away from the incoming flow direction of the air flow in the volute casing, thereby effectively avoiding direct impact of the air flow and further reducing the generation of abnormal sound. That is, during rotation of the volute tongue 20 relative to the volute body, there is a first limit condition close to the first end 131 of the annular wall 13 and a second limit condition away from the first end 131 of the annular wall 13, and in the first limit condition of the volute, the plane of the volute tongue 20 is substantially parallel to the plane of the second end 132 of the annular wall 13, specifically, the rotation track of the volute tongue 20 is shown by the dotted line in the figure. The position of the first limit state and the second limit state may be defined by the length of the second strip-shaped chute 16 or the shape of the first arc-shaped wall 14.

The length of the volute tongue piece 20 of the volute can be adjusted in a telescopic mode in the rotating process, wherein in the rotating process of the volute tongue piece 20, the end portion of the volute tongue piece 20 cannot be exposed out of the plane where the air outlet 15 of the volute is located, and therefore the problem of interference between the volute tongue piece 20 and a pipe connected to the air outlet 15 cannot occur. On the other hand, when the volute tongue piece 20 rotates to different angles, the length of the volute tongue piece 20 can be adjusted in a telescopic mode, so that the plane where the air outlet 15 of the volute casing is located cannot change, namely in the rotation process of the volute tongue piece 20, the problems that extra airflow separation is caused due to the fact that the wall plate on the volute tongue side is shortened, resistance is formed due to the fact that the wall plate on the volute tongue side is lengthened to extrude the airflow at the outlet, and the like cannot occur, and the airflow at the air outlet of the volute casing can still reach the optimal flowing state after the angle of the volute tongue piece 20 is adjusted. In this embodiment, the rotation connection portion 210 of the volute tongue member 20 is located inside the first arc-shaped wall 14, and the first arc-shaped wall 14 determines the position of the throat portion of the air outlet 15 of the volute, so that the air outlet area of the throat portion of the centrifugal fan is not affected before and after the adjustment of the outlet angle at the volute tongue side and in the adjustment process, and therefore, the performance of the fan is not changed suddenly, and the normal and stable operation of the fan is ensured.

Example 2

Referring to fig. 11 and 12, the present embodiment is different from embodiment 1 in that: the relative sliding between the first plate 23 and the second plate 24 is achieved by means of a slider 26 cooperating with a bar-shaped runner. Specifically, one of the first plate 23 and the second plate 24 has a first strip-shaped sliding groove 25 arranged along the extending direction thereof, and the other has a sliding block 26 slidably constrained in the first strip-shaped sliding groove 25. Preferably, the first strip-shaped sliding grooves 25 are formed in the second plate 24, specifically, the first strip-shaped sliding grooves 25 are respectively formed on both lateral sides of the upper surface of the second plate 24, the notches of the two strip-shaped sliding grooves are oppositely arranged, and correspondingly, sliding blocks 26 capable of being clamped into the first strip-shaped sliding grooves 25 are formed on both lateral sides of the lower surface of the first plate 23.

Example 3

Referring to fig. 13 and 14, the present embodiment is different from embodiment 1 in that: the first plate 23 and the second plate 24 are slidably connected by a slide rail 27. In order to ensure the smoothness of the relative movement between the first plate 23 and the second plate 24, the slide rail 27 of the present embodiment is preferably a ball slide rail 27, and the ball slide rail 27 is disposed between two opposite planes of the first plate 23 and the second plate 24, and connects the first plate 23 and the second plate 24.

Claims (10)

1. A volute for a centrifugal fan, comprising:

the volute comprises a volute body and a volute body, wherein the volute body comprises a rear cover plate (11), a front cover plate (12) and a ring wall (13), the front cover plate (12) is arranged opposite to the rear cover plate (11), the ring wall (13) is arranged between the front cover plate (12) and the rear cover plate (11) and is provided with a first end portion (131) and a second end portion (132) which are opposite in the length direction;

the volute tongue piece (20) is rotatably connected to the first end part (131) of the annular wall (13) and defines an air outlet (15) with an adjustable divergence angle together with the rear cover plate (11), the front cover plate (12) and the second end part (132) of the annular wall (13);

the method is characterized in that: the volute tongue piece (20) is of a plate-shaped structure with the length capable of being adjusted in a telescopic mode, the plate-shaped structure is provided with a first connecting end (21) and a second connecting end (22) which are opposite in the length direction, the first connecting end (21) of the volute tongue piece (20) is rotatably connected to the first end (131) of the annular wall (13), and the second connecting end (22) of the volute tongue piece (20) is constrained on at least one of the front cover plate (12) and the rear cover plate (11) in a sliding mode along the plane where the air outlet (15) is located.

2. The volute for a centrifugal fan according to claim 1, wherein: the volute tongue piece (20) comprises a first plate (23) and a second plate (24), the first plate (23) is connected with the first end (131) of the annular wall (13), the second plate (24) is connected with at least one of the front cover plate (12) and the rear cover plate (11), and the first plate (23) and the second plate (24) are constrained together in a relatively sliding mode.

3. The volute for a centrifugal fan according to claim 2, wherein: the first plate (23) and the second plate (24) are connected in a magnetic attraction mode.

4. The volute for a centrifugal fan according to claim 2, wherein: one of the first plate (23) and the second plate (24) is provided with a first strip-shaped sliding groove (25) arranged along the extending direction of the first plate, and the other one is provided with a sliding block (26) which can be correspondingly and slidably constrained in the first strip-shaped sliding groove (25).

5. The volute for a centrifugal fan according to claim 2, wherein: the first plate (23) and the second plate (24) are connected in a sliding mode through a sliding rail (27).

6. The volute for a centrifugal fan according to claim 5, wherein: the slide rail (27) is a ball slide rail (27) and is arranged between two planes opposite to the first plate (23) and the second plate (24).

7. The volute for a centrifugal fan according to any of claims 1-6, wherein: two opposite side surfaces of the front cover plate (12) and the rear cover plate (11) adjacent to the air outlet (15) are respectively provided with a second strip-shaped sliding groove (16), two transverse sides of a second connecting end (22) of the worm piece (20) are provided with convex columns (241), and the two convex columns (241) are respectively constrained in the corresponding second strip-shaped sliding grooves (16) in a sliding manner.

8. The volute for a centrifugal fan according to any of claims 1-6, wherein: the volute tongue piece (20) has a first limit state close to the second end (132) of the annular wall (13) and a second limit state far away from the second end (132) of the annular wall (13) in the process of rotating relative to the volute body, and the plane of the volute tongue piece (20) is basically parallel to the plane of the second end (132) of the annular wall (13) in the first limit state of the volute.

9. The volute for a centrifugal fan according to any of claims 1-6, wherein: the volute is provided with an axis (O), an output shaft of the driving motor (28) is parallel to the axis (O) of the volute, and the output shaft of the driving motor (28) is connected with the first connecting end (21) of the volute tongue piece (20) so as to drive the volute tongue piece (20) to rotate around the output shaft of the driving motor (28).

10. A centrifugal fan, its characterized in that: use of a volute for a centrifugal fan according to any of claims 1 to 9.

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