CN111207112B

CN111207112B - Centrifugal fan and range hood with same

Info

Publication number: CN111207112B
Application number: CN202010014411.1A
Authority: CN
Inventors: 张青青; 翁建松; 陈旭斌
Original assignee: Ningbo Fotile Kitchen Ware Co Ltd
Current assignee: Ningbo Fotile Kitchen Ware Co Ltd
Priority date: 2020-01-07
Filing date: 2020-01-07
Publication date: 2021-10-01
Anticipated expiration: 2040-01-07
Also published as: CN111207112A

Abstract

The invention discloses a centrifugal fan, which comprises a volute, an impeller arranged in the volute and a motor used for driving the impeller to rotate, wherein the volute comprises a ring wall, and the centrifugal fan is characterized in that: the spiral case is internally provided with a waveform conversion device for converting noise spherical waves generated by motor vibration into plane waves, the waveform conversion device comprises at least two waveform conversion units, and each waveform conversion unit is tightly attached to the inner side of the annular wall. Also discloses a range hood applying the centrifugal fan. Compared with the prior art, the invention has the advantages that: the broadband noise source signal characteristic with the amplitude changing along with the propagation path is equivalent to a plane wave with the noise signal amplitude in a specific frequency range not changing along with the propagation path through a waveform conversion structure, so that the amplitude of the sound wave does not change along with the propagation distance, the noise amplitude at any position from a motor to the volute annular wall is the same, the accurate noise amplitude at the same reference value is used for noise reduction, and the noise reduction effect can be greatly improved.

Description

Centrifugal fan and range hood with same

Technical Field

The invention relates to a power device, in particular to a centrifugal fan and a range hood applying the centrifugal fan.

Background

The range hood works by utilizing the fluid dynamics principle, sucks and exhausts oil smoke through a centrifugal fan arranged in the range hood, and filters partial grease particles by using a filter screen. The centrifugal fan comprises a volute, an impeller arranged in the volute and a motor driving the impeller to rotate. When the impeller rotates, negative pressure suction is generated in the center of the fan, oil smoke below the range hood is sucked into the fan, accelerated by the fan and then collected and guided by the volute to be discharged out of a room.

The investigation result shows that the experience perception of a user in the cooking process mostly depends on the noise and the air volume of the range hood, but the improvement of the air volume and the reduction of the noise are contradictory, and the noise is inevitably increased while the air volume is increased, so that the priority cannot be set on the two parameters in the design process, and only the consideration can be given to the two parameters at the same time, and the use experience of the user is inevitably influenced.

The research mode in the prior art is generally passive control, namely sound absorption materials such as sound absorption cotton are attached to a fan system to perform sound absorption and noise reduction or active noise reduction, and noise reduction is realized based on active noise reduction and other modes. In the traditional active noise reduction, a sound wave with the same frequency and amplitude and opposite phase is formed for noise waves to offset so as to achieve the aim of noise elimination. For example, the active noise reduction device disclosed in chinese patent application No. 201810198990.2 is disposed between a fan device and a mesh enclosure, and includes a resonant cavity and a speaker, where an oil path is disposed on the resonant cavity, so that dirty oil on the fan device can drop on the resonant cavity, and is guided into a housing device through the oil path, and flows into an oil cup. The loudspeaker in the active noise reduction device is electrically connected with the control device of the range hood, the active resonance system also comprises a noise acquisition element, and the noise acquisition element is also electrically connected with the control device; when the range hood is opened, the noise collection element can collect the noise in the range hood, including the noise that the fan device produced, air current striking wind channel structure, the collision noise of screen panel etc., and transmit the noise of gathering for controlling means with the mode of signal of telecommunication, controlling means will gather the noise signal and calculate the department and fall the acoustic signal of making an uproar, and the control signal of control speaker broadcast is input in view of the above, make the speaker can send the corresponding sound wave of making an uproar of falling, the sound wave amplitude that should fall the sound wave of making an uproar and noise is the same, the opposite phase place, two opposite sound waves offset each other like this, thereby, play the purpose of making an uproar.

However, the active noise reduction has the defects that the noise elimination effect is uneven, the noise at the position is enhanced while the noise at the other positions is eliminated, and the defects brought by the method are not effectively solved at present.

The noise generated by the operation of the range hood belongs to a complex noise, and is the complex sound generated by air flow noise, rotation noise and structure noise mixed with the energy input by the motor and the impeller in the volute and transmitted to human ears. In the fan system, sound is transmitted outwards from an excitation source layer by layer, in the process, the motor is used as the excitation source and is spherical wave which is radiated and transmitted outwards by taking a wave front as a spherical surface, the amplitude of the spherical wave is in inverse proportion to the transmission distance, so that the noise amplitudes at different positions in the volute are different, and the noise reduction effect is not ideal no matter sound absorption cotton or active noise reduction is adopted and the noise cannot be reduced selectively and strongly aiming at different positions.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide a centrifugal fan, which can improve noise reduction capability and realize silence, in view of the above problems in the prior art.

The second technical problem to be solved by the invention is to provide a range hood with the centrifugal fan.

The technical scheme adopted by the invention for solving the first technical problem is as follows: the utility model provides a centrifugal fan, includes the spiral case, sets up the impeller in the spiral case and is used for driving the rotatory motor of impeller, the spiral case includes the rampart, its characterized in that: the spiral case is internally provided with a waveform conversion device for converting noise spherical waves generated by motor vibration into plane waves, the waveform conversion device comprises at least two waveform conversion units, and each waveform conversion unit is tightly attached to the inner side of the annular wall.

In order to facilitate the targeted noise reduction of different noise levels at different positions in the fan, the molded line of the volute is at least divided into at least two partitions along the circumferential direction, and the noise amplitude in each partition is equal.

Preferably, the waveform conversion unit is a hollow cylinder or a rectangular parallelepiped.

Preferably, the waveform conversion unit is cylindrical, an axial direction of the waveform conversion unit is parallel to an axial direction of the scroll casing, and a cutoff frequency of the waveform conversion unit is f_ucAnd is and

in the formula c₀The sound velocity is the sound velocity, r is the radius of the section of the waveform conversion unit, one or at least two waveform conversion units are arranged in each partition, and the radius of the waveform conversion unit or the sum of the radii of the sections of the waveform conversion units is not more than the arc length of the volute type line of the corresponding partition.

Preferably, the volute further comprises a volute tongue, the center of the volute line is used as a starting point, the center of the volute line is used as a circle center, a connecting line of the circle center and the starting point is used as a first partition line, the first partition line rotates clockwise around the circle center by a certain angle to obtain a second partition line, an area between the first partition line and the second partition line is a first partition, and the second partition line extends to the ring wall from the circle center; the second partition line rotates clockwise around the circle center by a certain angle to obtain a third partition line, the area between the second partition line and the third partition line is a second partition, and the third partition line extends to the ring wall from the circle center; by analogy, the total number of the partitions and the partition lines is x, and the x-th partition is arranged between the x-1 th partition line and the first partition line.

Preferably, the lengths of the respective two partitioning lines of the nth partition are ln and ln +1, respectively, and satisfy ln ≈ (0.9l (n +1), l (n +1)), n ∈ (1,2,3 … x).

Preferably, x is 7, the third division line rotates clockwise around the center of circle by a certain angle to obtain a fourth division line, the area between the third division line and the fourth division line is a third division, and the fourth division line extends from the center of circle to the annular wall; the fourth division line rotates clockwise around the circle center for a certain angle to obtain a fifth division line, the area between the fourth division line and the fifth division line is a fourth division, and the fifth division line extends to the annular wall from the circle center; the fifth partition line rotates clockwise around the circle center by a certain angle to obtain a sixth partition line, the area between the fifth partition line and the sixth partition line is a fifth partition, and the sixth partition line extends from the circle center to the annular wall; the sixth partition line rotates clockwise around the circle center by a certain angle to obtain a seventh partition line, the area between the sixth partition line and the seventh partition line is a sixth partition, and the seventh partition line extends to the ring wall from the circle center; and the area between the seventh partition line and the first partition line is a seventh partition.

Preferably, the length of the first partition line is l1, the length of the second partition line is l2, the length of the third partition line is l3, the length of the fourth partition line is l4, the length of the fifth partition line is l5, the length of the sixth partition line is l6, and the length of the seventh partition line is l7, where the lengths satisfy the following relationships: l1 ≈ 0.9 × l2, l2), l2 ≈ 0.9 × l3, l3, l3 ≈ 0.9 × l4, l4, l4 ≈ 0.9 ≈ l5, l5, l5 ≈ 0.9 × l6, l6, l6 ≈ 0.9 ≈ l7, l 7.

Preferably, the waveform conversion unit is made of a deformable material in order to facilitate changing the cutoff frequency of the waveform conversion unit.

The technical scheme adopted by the invention for solving the second technical problem is as follows: a range hood comprises the centrifugal fan.

Compared with the prior art, the invention has the advantages that: the broadband noise source signal characteristic with the amplitude changing along with the propagation path is equivalent to a plane wave with the noise signal amplitude in a specific frequency range not changing along with the propagation path through a waveform conversion structure, so that the amplitude of the sound wave does not change along with the propagation distance, the noise amplitude at any position from a motor to the volute annular wall is the same, the accurate noise amplitude at the same reference value is used for noise reduction, and the noise reduction effect can be greatly improved; the regional noise reduction method is adopted for reducing noise pertinently according to different noise levels at different positions of the centrifugal fan, the self-adaptive level is high, and the noise reduction effect is obvious.

Drawings

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

FIG. 2 is a schematic view of a centrifugal fan according to an embodiment of the present invention with a hidden impeller and hidden motor;

FIG. 3 is a cross-sectional view of FIG. 2;

FIG. 4 is a schematic view of a partition of a volute of a centrifugal fan in accordance with an embodiment of the present invention;

fig. 5 is a schematic view of a waveform converting unit of a noise reducing device of a centrifugal fan according to an embodiment of the present invention;

FIG. 6 is a schematic view of a point source propagation path;

FIG. 7 is a schematic diagram of a signal encoder processing a signal;

fig. 8 is a schematic diagram of a signal decoder processing a signal.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar functions.

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.

Referring to fig. 1 to 4, a centrifugal fan includes a volute 1, an impeller 2 disposed in the volute 1, and a motor 3 for driving the impeller 2 to rotate. The centrifugal fan is mainly used in the range hood, and can be used for any other occasions needing the centrifugal fan as power instead.

The inside of the peripheral wall of the scroll casing 1 is provided with a waveform conversion device 4. The volute 1 comprises a front cover 11, a rear cover 12 and a ring wall 13 arranged between the front cover 11 and the rear cover 12, and the volute 1 further comprises a volute tongue 14 and an air outlet 15. In the present embodiment, the waveform conversion means 4 is provided on the annular wall 13.

A sound wave is an audio signal that is received and perceived by the human auditory system as varying in intensity and pitch due to the pressure and propagation frequency of the signal (sound wave). The process of generating noise in the centrifugal fan of the range hood is as follows: when the sound wave propagates outward from the motor 3 with the wave front as a sphere, the noise amplitude at different positions of the annular wall 13 will be different due to different propagation distances when the sound wave propagates to the annular wall 13 of the volute 1. The centrifugal fan of the range hood is regarded as a circular structure taking the position of the output shaft of the motor 3 as the center O ", and the center O" is regarded as a noise source, and the propagation path from the noise source to the annular wall 13 is approximately understood as shown in fig. 6, wherein when the radius is R, the surface area is a, and when the radius is 2R, the surface area is 4A.

According to the theory of the figure, the intersecting area of the plane where two critical positions with equal distances from the noise source (the motor 3) to the annular wall 13 are located and the annular wall 13 is defined as an equal noise amplitude area, the centrifugal fan is divided into 7 equal noise amplitude areas (the 7 th equal noise amplitude area is the area corresponding to the air outlet cover) according to the method, and the radius and the corresponding area central angle of each equal amplitude area are obtained, which is shown in fig. 4. The dashed circle in fig. 4 is a virtual reference circle (a circle having the largest radius inside the scroll casing 1) centered on a point on the axis where the output shaft of the motor 3 is located.

In the present embodiment, it is preferable to divide the annular wall 13 of the scroll casing 1 into 7 sections, specifically, the plane where the front cover 11 is located is the reference plane, on the plane, the position intersecting the axis of the output shaft of the motor 3 is set as a center O (center of the molded line of the volute 1), the center of the volute tongue 14 is set as a starting point O ', a line connecting the center O and the starting point O' is set as a first divisional line L1 of the divisional areas, the length of the spiral case is L1, the spiral case rotates a certain angle around the clockwise direction (the spiral case molded line is generally a spiral line, and the direction from the starting point to the end point of the spiral line is the clockwise direction) to obtain a second partition line L2, the area between the spiral case molded line and the second partition line is a first partition Q1, the second partition line L2 extends to the annular wall 13 from the circle center O, the length of the partition is l2, the noise amplitudes of all points in the first partition Q1 and the molded line of the annular wall 13 (namely the molded line of the volute) are equal, namely the partition is an equal-amplitude area, and the relation between l1 and l2 meets the following requirements: l1 ≈ (0.9 × l2, l 2); the second partition line L2 rotates clockwise around the circle center O by a certain angle to obtain a third partition line L3, the area between the second partition line L3 and the third partition line L3 is a second partition Q2, the third partition line L3 extends to the position of the annular wall 13 from the circle center O, the length of the third partition line L3 is L3, the noise amplitudes of all points of the molded line of the annular wall 13 in the second partition Q2 are equal, and the relation between L2 and L3 meets the following requirements: l2 ≈ (0.9 × l3, l 3); the third partition line L3 rotates clockwise around the circle center O by a certain angle to obtain a fourth partition line L4, the area between the third partition line and the fourth partition line is a third partition Q3, the fourth partition line L4 extends from the circle center O to the annular wall 13, the length of the fourth partition line L4 is L4, the noise amplitudes of all points of the molded line of the annular wall 13 in the third partition Q3 are equal, and the relation between L3 and L4 satisfies the following conditions: l3 ≈ (0.9 × l4, l 4); the fourth partition line L4 rotates clockwise around the center O by a certain angle to obtain a fifth partition line L5, the area between the fourth partition line and the fifth partition line is a fourth partition Q4, the fifth partition line L5 extends from the center O to the annular wall 13, the length of the fifth partition line L5 is L5, the noise amplitudes of all points of the molded line of the annular wall 13 in the fourth partition Q4 are equal, and the relation between L4 and L5 satisfies the following conditions: l4 ≈ (0.9 × l5, l 5); the fifth partition line L5 rotates clockwise around the circle center O by a certain angle to obtain a sixth partition line L6, the area between the fifth partition line and the sixth partition line is a fifth partition Q5, the sixth partition line L6 extends from the circle center O to the position of the annular wall 13, the length of the sixth partition line L6 is L6, the noise amplitudes of all points of the molded line of the annular wall 13 in the fifth partition Q5 are equal, and the relation between L5 and L6 satisfies the following conditions: l5 ≈ (0.9 × l6, l 6); the sixth partition line L6 rotates clockwise around the circle center O by a certain angle to obtain a seventh partition line L7, the area between the sixth partition line and the seventh partition line is a sixth partition Q6, the seventh partition line L7 extends from the circle center O to the annular wall 13, the length of the seventh partition line L7 is L7, the noise amplitudes of all points of the molded line of the annular wall 13 in the sixth partition Q6 are equal, and the relation between L6 and L7 satisfies the following conditions: l6 ≈ (0.9 × l7, l 7). The seventh partition Q7 is located between the first partition line L1 and the seventh partition line L7, and corresponds to the air outlet 15 of the scroll casing 1.

If l1 ≈ 0.9l2, the central angle θ and arc length l of the first partition Q1 can be determined, so the partition criteria for the equal-amplitude region, i.e., lx ≈ 0.9l (x +1), x ∈ (1,2,3 … 6), 1,2,3 … 6 refer to the partition index. That is, the lengths of the respective two partitioning lines at the nth partition are ln and ln +1, respectively, and ln ≈ 0.9l (n +1), l (n +1)), n ∈ (1,2,3 … x) is satisfied.

Therefore, 7 equal noise amplitude regions are arranged in the centrifugal fan, the amplitudes of the noise are the same (on the premise of single frequency), the distributed frequency band is too wide and is the reason that the noise reduction effect of the second traditional noise reduction means is poor, the noise amplitudes are the same, the noise of almost every noise frequency band is distributed, the noise amplitudes of different frequency bands are overlapped to generate new noise, and therefore the noise reduction difficulty is increased.

As described above, the noise source radiates outwards in space around the wave front to be heard by human ears, and the traditional passive noise reduction and active noise reduction based on the complex characteristics of the noise have poor effect. Therefore, the waveform conversion apparatus 4 of the present invention includes a plurality of waveform conversion units 41 as the waveform conversion structure, and each waveform conversion unit 41 has a hollow cylindrical shape or a rectangular parallelepiped shape. The waveform conversion structure can constrain three-dimensional spherical waves into plane waves in a certain frequency band. The axial two ends of each wave conversion unit 41 respectively face the front cover 11 and the rear cover 12 of the volute 1 (i.e. the axial direction of the wave conversion unit 41 is parallel to the axial direction of the volute 1) and are fixedly connected, and the peripheral wall is attached to the annular wall 13 of the volute 1. The waveform conversion unit 41 is used as a waveform conversion structure, and is characterized in that three-dimensional spherical sound waves lower than the cut-off frequency of the structure can be converted into one-dimensional plane sound waves, and the noise amplitude is restricted to the same value, so that the noise frequency of each region can be offset and reduced one-to-one through the structure.

The waveform conversion unit 41 may be made of a deformable material, and the frequency range is changed by applying a pre-tightening force to two ends so that the change of the radius is caused. The cross-sectional shape of the waveform conversion unit 41 has two and only two options: round and square, and thus may be cylindrical and rectangular parallelepiped in shape. The same principle applies, i.e. both below the cut-off frequency of the conversion structure. The differences of different shapes are reflected in the calculation of the cut-off frequency and some size parameters based on the shapes calculated according to the cut-off frequency, so that the arrangement form in the centrifugal fan is influenced. In the present embodiment, the waveform converting unit 41 is a cylinder, for example, see fig. 5. The waveform transformation units 41 distributed in each partition have the same length and different radii, the radii of the waveform transformation units 41 are limited by the arc length l of each partition of the volute 1 and the noise frequency f of the partition, and the length is the same as the thickness of the volute 1.

The spectrum distribution of each subarea is obtained by carrying out spectrum sampling on the existing centrifugal fan, and the frequency distribution range of the first subarea Q1 is as follows: 2800 to 2500 Hz; second partition Q2 frequency distribution range: 2500-2200 Hz; third partition Q3 frequency distribution range: 2200 to 1700 Hz; fourth section Q4 frequency distribution range: 1700-1500 Hz; fifth partition Q5 frequency distribution range: 1500-500 Hz; sixth partition Q6 frequency distribution range: 500-300 Hz; seventh partition Q7 frequency distribution range: 300 to 100 Hz.

Taking the first partition Q1 as an example, according to the basic wave equation of acoustics and the cylindrical Bessel function

It is known that when m is 0 and n is 0,

when the frequency of the noise source is lower than f₀₀In time, spherical waves reach the condition of conversion into plane waves. Therefore, the cut-off frequency of the plane wave conversion structure is designed to be f_ucAnd is and

in the formula c₀R is the radius of the cross section of the waveform conversion unit 41. The noise frequency distribution range of the first sub-section Q1 is 2800 to 2500Hz, and 100Hz is used as the interval,

the radius r of the first waveform conversion unit 41 of the partition is determined₁In turn, are

The radius r of the second waveform conversion unit 41 (in order of the clockwise direction) of the region is determined₂By analogy, r is obtained_n，r₁+r₂+…+r_nL is less than or equal to l. Other or first partitions Q1 may be spaced at 100Hz or other desired frequency when waveform conversion units 41 are provided, thereby determining the number of waveform conversion units 41 within that partition.

Preferably, the number of the waveform converting units 41 of each section is 3 in the first section Q1, 2 in the second section Q2, 7 in the third section Q3, 2 in the fourth section Q4, 17 in the fifth section Q5, 5 in the sixth section Q6, and 4 in the seventh section Q7, and the radius of each waveform converting unit 41 is obtained from the above relationship. Alternatively, other numbers and radii may be used, as long as the noise amplitude value propagated from the noise source into each partition due to the inconsistency of propagation paths is different, and the noise amplitude value of different frequency segments in each partition is converted to the same level.

The noise signals of each equal noise amplitude area are obtained, coding is carried out based on the original noise signals, each waveform conversion unit 41 of each partition is in wireless connection with a main controller of the range hood, and a signal coding and decoding modulator is used for calling frequency spectrum information of each partition based on a noise sample stored in the main controller to generate a new noise signal through steps of coding, decoding and the like so as to offset noise in the centrifugal fan and play a role of noise reduction. Referring to fig. 7 and 8, the specific signal processing procedure is the same as that of the prior art, for example, the active noise reduction device mentioned in the background art is adopted, the speakers thereof are arranged in different partitions, and the noise of the corresponding frequency is emitted for cancellation.

Alternatively, the waveform conversion unit 41 may be arranged in layers along the axial direction of the scroll casing 1, and it is also possible to arrange the waveform conversion unit 41 in each layer along the same line locus as the line locus of the scroll casing 1.

Claims

1. A centrifugal fan, includes spiral case (1), sets up impeller (2) in spiral case (1) and is used for driving impeller (2) pivoted motor (3), spiral case (1) includes rampart (13), its characterized in that: the novel flat-plate vibration noise reduction volute is characterized in that a waveform conversion device (4) used for converting noise spherical waves generated by vibration of the motor (3) into plane waves is arranged in the volute (1), the waveform conversion device (4) comprises at least two waveform conversion units (41), each waveform conversion unit (41) is tightly attached to the inner side of the annular wall (13), the molded line of the volute (1) is at least divided into at least two partitions along the circumferential direction, and the noise amplitude in each partition is equal.

2. The centrifugal fan of claim 1, wherein: the waveform conversion unit (41) is in a hollow cylindrical shape or a rectangular parallelepiped shape.

3. The centrifugal fan of claim 2, wherein: the waveform conversion unit (41) is cylindrical, the axial direction of the waveform conversion unit (41) is parallel to the axial direction of the volute (1), and the cut-off frequency of the waveform conversion unit (41) is f_ucAnd is and

in the formula c₀And r is the radius of the section of the waveform conversion unit (41), one or at least two waveform conversion units (41) are arranged in each partition, and the radius of the waveform conversion unit (41) or the sum of the radii of the sections of the waveform conversion units (41) is not more than the volute type line arc length of the corresponding partition.

4. The centrifugal fan according to any one of claims 1 to 3, wherein: the volute (1) further comprises a volute tongue (14), the center of the volute (14) is used as a starting point (O '), the center of the molded line of the volute (1) is used as a center of the circle (O), the connecting line of the center of the circle (O) and the starting point (O') is used as a first partition line (L1), the first partition line (L1) rotates clockwise around the center of the circle (O) for a certain angle to obtain a second partition line (L2), the area between the first partition line (L1) and the second partition line (L2) is a first partition (Q1), and the second partition line (L2) extends from the center of the circle (O) to the annular wall (13); the second partition line (L2) rotates clockwise around a circle center (O) by a certain angle to obtain a third partition line (L3), the area between the second partition line (L2) and the third partition line (L3) is a second partition (Q2), and the third partition line (L3) extends from the circle center (O) to the annular wall (13); by analogy, there are x partitions and x partition lines, with the x-th partition between the x-1 th partition line and the first partition line (L1).

5. The centrifugal fan of claim 4, wherein: the lengths of the corresponding two partition lines of the nth partition are ln and ln +1, respectively, and satisfy ln ≈ 0.9l (n +1), l (n +1)), n ∈ (1,2,3 … x).

6. The centrifugal fan of claim 4, wherein: x is 7, the third partition line (L3) rotates clockwise around the center (O) by a certain angle to obtain a third partition line (L4), the area between the third partition line (L3) and the fourth partition line (L4) is a third partition (Q3), and the fourth partition line (L4) extends from the center (O) to the annular wall (13); the fourth partition line (L4) rotates clockwise around a circle center (O) by a certain angle to obtain a fifth partition line (L5), the area between the fourth partition line (L4) and the fifth partition line (L5) is a fourth partition (Q4), and the fifth partition line (L5) extends from the circle center (O) to the annular wall (13); the fifth partition line (L5) rotates clockwise around a circle center (O) by a certain angle to obtain a sixth partition line (L6), the area between the fifth partition line (L5) and the sixth partition line (L6) is a fifth partition (Q5), and the sixth partition line (L6) extends from the circle center (O) to the annular wall (13); the sixth partition line (L6) rotates clockwise around a circle center (O) by a certain angle to obtain a seventh partition line (L7), the area between the sixth partition line (L6) and the seventh partition line (L7) is a sixth partition (Q6), and the seventh partition line (L7) extends from the circle center (O) to the ring wall (13); the region between the seventh division line (L7) and the first division line (L1) is a seventh division (Q7).

7. The centrifugal fan of claim 6, wherein: the length of the first partition line (L1) is L1, the length of the second partition line (L2) is L2, the length of the third partition line (L3) is L3, the length of the fourth partition line (L4) is L4, the length of the fifth partition line (L5) is L5, the length of the sixth partition line (L6) is L6, and the length of the seventh partition line (L7) is L7, which satisfy the following relations: l1 ≈ 0.9 × l2, l2), l2 ≈ 0.9 × l3, l3, l3 ≈ 0.9 × l4, l4, l4 ≈ 0.9 ≈ l5, l5, l5 ≈ 0.9 × l6, l6, l6 ≈ 0.9 ≈ l7, l 7.

8. The centrifugal fan of claim 1, wherein: the waveform conversion unit (41) is made of a deformable material.

9. A range hood, its characterized in that: comprising a centrifugal fan according to any one of claims 1 to 8.