CN110454421B

CN110454421B - Centrifugal fan and noise reduction control method thereof

Info

Publication number: CN110454421B
Application number: CN201910701914.3A
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: 2019-07-31
Filing date: 2019-07-31
Publication date: 2020-09-01
Anticipated expiration: 2039-07-31
Also published as: CN110454421A

Abstract

The invention discloses a centrifugal fan, which comprises a volute, an impeller and a noise reduction device, wherein the volute comprises a ring wall and a volute tongue, and is characterized in that: the annular wall is divided into at least two subareas, the noise reduction device is an active noise reduction device, and the active noise reduction device comprises a laser displacement sensor arranged on the impeller and a noise reduction assembly arranged in each subarea and used for performing targeted noise reduction on noise in the corresponding subarea according to the displacement value measured by the laser displacement sensor. Also discloses a range hood applying the centrifugal fan and a noise reduction control method of the centrifugal fan. Compared with the prior art, the invention has the advantages that: the annular wall of the volute is partitioned, noise in each partition is reduced, targeted noise reduction can be achieved, and noise reduction capability is improved.

Description

Centrifugal fan and noise reduction control method thereof

Technical Field

The invention relates to a power device, in particular to a centrifugal fan and a noise reduction control method of the centrifugal fan.

Background

The centrifugal fan is a power device which rotates through an impeller in the fan, enables air near the impeller to rotate along with the impeller when in work, generates centrifugal motion, and can convert the centrifugal motion into fan pressure under the blocking effect of a fan volute, and therefore, a certain air flow is generated. The centrifugal fan has the advantages of simple structure installation, large ventilation volume, high wind pressure and the like, thereby being widely applied to oil fume purification equipment and air purification equipment.

However, centrifugal fans have a significant disadvantage in that they are noisy to operate. This noise has a significant influence on the life, work, etc. of people. The main noise sources of centrifugal fans include: aerodynamic noise, electromagnetic noise, and mechanical noise.

The prior art mainly solves the problem of motor noise in the external part, such as the front cover plate of a fan system and other positions, and the method has the defects that the noise reduction effect is not obvious and the noise of different frequency bands cannot be reduced in a targeted manner. Therefore, some noise-reducing centrifugal fans are available, for example, a centrifugal fan volute adopting particle damping vibration reduction disclosed in chinese patent application No. 201510114450.8 includes a volute body, the volute body is provided with an air inlet, the volute body is composed of an inner volute and an outer volute, a vibration-reducing and noise-reducing chamber is formed between the inner volute and the outer volute, and damping vibration-reducing particles are filled in the vibration-reducing and noise-reducing chamber. The noise detection and noise reduction are mainly based on a semi-anechoic chamber method, then the size parameters of a volute or an impeller are changed, the noise reduction test is repeatedly carried out, the purpose of noise reduction is achieved by further iterative optimization through test result comparison, and the method has the defects of low contrast, repeated machinery and poor effect.

In addition, some active noise reduction methods are commonly used for noise reduction at present, an active noise reduction device is composed of a noise signal acquisition module, a signal processing analysis module (mainly comprising a control chip and a signal amplifier) and a sound source generator module, the three modules are electrically connected through a wire, the noise acquisition module is used for acquiring noise and transmitting the noise to the noise processing analysis module, the noise processing analysis module performs spectrum analysis on the received signal to form a noise reduction sequence signal, and the sequence signal is transmitted to the sound source generator module (such as a loudspeaker); and the sound source generator module sends reverse sound waves with the same amplitude and the opposite phase as the noise signals according to the noise reduction sequence signals, so that the noise is eliminated. However, because the noise in the fan system of the range hood is a series of noises such as eddy noise and rotational noise, the noise collected is a reverberant sound mixed with a lot of irrelevant spectrum noises, and for the special use environment and operation of the fan system of the range hood, the requirement on the position of the noise collecting module is high, the position arrangement is not proper, the collected noise does not have reliability, the processing at the later stage is invalid, that is, the analysis processing module very easily analyzes the reverse sound wave which is completely not corresponding to the spectrum and the phase of the noise signal, and the noise reduction effect is very poor, so that further improvement is needed.

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 third technical problem to be solved by the invention is to provide a noise reduction control method of 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 spiral case, impeller and falls the device of making an uproar, the spiral case includes rampart and volute tongue, its characterized in that: the annular wall is divided into at least two subareas, the noise reduction device is an active noise reduction device, and the active noise reduction device comprises a laser displacement sensor arranged on the impeller and a noise reduction assembly arranged in each subarea and used for performing targeted noise reduction on noise in the corresponding subarea according to the displacement value measured by the laser displacement sensor.

In order to reduce the noise in each partition more effectively by making the difference of the mean values of the noise in each partition not large, the curvature radius of the profile of each volute in each partition is the same.

Preferably, a point at the volute tongue is taken as a starting point, the center of the volute molded line is taken as a circle center, a connecting line of the circle center and the starting point is taken as a base line of the partition, the base line rotates clockwise around the circle center for a certain angle to obtain a first partition line, and an area between the base line and the first partition line is a first partition; the first partition line rotates clockwise around the circle center by a certain angle to obtain a second partition line, and the area between the first partition line and the second partition line is a second partition; the second partition line rotates clockwise around the circle center by a certain angle to obtain a third partition line, and the area between the second partition line and the third partition line is a third partition; the third partition line rotates clockwise around the circle center for a certain angle to obtain a fourth partition line, and the area between the third partition line and the fourth partition line is a fourth partition; the area between the fourth division line and the base line is a fifth division.

In order to be able to better match the noise, the noise reduction assembly comprises at least two sound source generators, the sound frequencies of which are different from each other.

In order to match the noise distribution in the fan and effectively reduce the noise in a targeted manner, the sound source generators with higher frequency spectrum phases are arranged closer to the front cover of the volute, and the frequency spectrum phases of the sound source generators are sequentially decreased in a clockwise direction along the annular wall molded line.

In order to automatically control the noise reduction assembly, the active noise reduction device further comprises a signal analysis processing module which outputs a reverse noise reduction sequence signal to the noise reduction assembly according to the signal of the laser displacement sensor.

The technical scheme adopted by the invention for solving the second technical problem is as follows: a range hood, its characterized in that: including a centrifugal fan as described above.

The technical scheme adopted by the invention for solving the third technical problem is as follows: the noise reduction control method of the centrifugal fan is characterized by comprising the following steps: the method comprises the following steps:

1) after the centrifugal fan normally operates for a certain time, the laser displacement sensor on the impeller starts to work;

2) when the laser displacement sensor rotates to each partition range along with the impeller, detecting the distance x between the laser displacement sensor and the annular wall, and matching corresponding rotating speed r for each different distance x;

3) the matched rotating speed is transmitted to a signal analysis processing module, and the signal analysis processing module extracts the corresponding relation between the current rotating speed and the noise frequency spectrum and phase parameters;

4) the signal analysis processing module outputs an optimal reverse noise reduction sequence corresponding to the current noise spectrum and phase parameters of the corresponding partition to the noise reduction assembly in each partition;

5) and the sound source generators in each subarea emit sound waves according to the received signals to offset and reduce the noise.

Preferably, in step 3), according to the formula f ═ rZ/60, f is a noise frequency, r is a rotation speed of the impeller, Z is a number of blades of the impeller, the signal analysis determines a frequency of the noise according to the rotation speed r, and the noise is subjected to FFT analysis, thereby obtaining a noise spectrum and phase information.

Compared with the prior art, the invention has the advantages that: the annular wall of the volute is partitioned, noise in each partition is reduced, targeted noise reduction can be achieved, and noise reduction capability is improved; by enabling the curvature radius in each partition to be the same, the average value difference of noise can be small, and partition noise reduction can be effectively carried out; the noise frequency and the phase are extracted by detecting the rotating speed, so that the detection is reliable, and the problems of more influencing factors and inaccurate detection in the direct detection of the noise are solved.

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 hidden impeller of a centrifugal fan in accordance with an embodiment of the present invention;

FIG. 3 is a front view of the surround of the volute of the centrifugal fan of an embodiment of the present invention;

fig. 4 is a schematic block diagram of an active noise reduction device of a centrifugal fan according to an embodiment of the present invention.

Detailed Description

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

Referring to fig. 1 to 4, a centrifugal fan includes a scroll casing 1 and an impeller 2, the scroll casing 1 includes a front cover 11, a rear cover (not shown), and an annular wall 12 disposed between the front cover 11 and the rear cover, and a scroll tongue 13 is formed on the above-mentioned components of the scroll casing 1. The centrifugal fan is mainly used in a range hood.

The centrifugal fan further comprises an active noise reduction device comprising an active noise reduction assembly arranged inside the circumferential wall 12, a laser displacement sensor 36 arranged on the impeller 2, in particular on the front ring of the impeller 2, and a signal analysis processing module 37 for receiving signals of the laser displacement sensor 36 to control the active noise reduction assembly, wherein the signal analysis processing module 36 may be arranged outside the volute 1, or in any other fixed position.

Even under the same rotating speed, the noise is different at different positions inside the volute 1, and the noise is maximum near the volute tongue 13. Therefore, the invention provides a scheme for reducing the noise of the volute in a partitioning mode.

Dividing the annular wall 12 of the volute 1 into 5 partitions, specifically, regarding the molded line of the annular wall 12 as an approximately circular structure, taking the circle center as O (on the axis of an impeller of a centrifugal fan applied to the volute), taking a point at the volute tongue 13 as a starting point O ', taking the connecting line of the circle center O and the starting point O ' as a baseline L1 of the partition, clockwise rotating a certain angle around the circle center O to obtain a first partition line L2, taking the area between the circle center O and the first partition line Q1, preferably, the angle between the circle center O and the starting point O ' as 45 degrees, and obtaining the same curvature radius of each point of the molded line of the annular wall 12 in the first partition line Q1, preferably 89 mm; the first partition line L2 rotates clockwise around the center O by a certain angle to obtain a second partition line L3, the area between the first partition line and the second partition line is a second partition Q2, the angle between the first partition line and the second partition line is preferably 65 degrees, the curvature radius of each point of the molded line of the annular wall 12 in the second partition Q2 is the same, and the curvature radius is preferably 101 mm; the second partition line L3 rotates clockwise around the circle center O by a certain angle to obtain a third partition line L4, the area between the second partition line L3 and the third partition line Q3 is a third partition, the preferred angle between the second partition line and the third partition line is 115 degrees, the curvature radius of each point of the molded line of the annular wall 12 in the third partition Q3 is the same, and the preferred curvature radius is 130 mm; the third division line L4 rotates clockwise around the center O by a certain angle to obtain a fourth division line L5, the area between the third division line L4 and the center O is a fourth division Q4, the angle between the fourth division line L3526 and the fourth division line Q3526 is preferably 80 degrees, the curvature radius of each point of the molded line of the annular wall 12 in the fourth division Q4 is the same, and the curvature radius is preferably 117 mm; the area between the fourth division line L5 and the base line L1 is a fifth division area Q5, and the curvature radius of each point of the molded line of the annular wall 12 in the fifth division area Q5 is the same, preferably 130 mm.

The subarea obtained by the method is that according to the noise test and simulation result and the design criterion, the first subarea Q1 is near the volute tongue, the second subarea Q2, the third subarea Q3, the fourth subarea Q4 and the fifth subarea Q5 are sequentially arranged in a clockwise rotation mode, the main reason is the difference of curvature radiuses, the curvature radiuses of all subareas are basically consistent, and the difference of the average values of the noise is not large, so that the subarea noise reduction and the complete coverage can be more effectively carried out, and the adjustment is more targeted.

The active noise reduction device of the invention is different from the traditional active noise reduction in that: 1) a noise signal acquisition module is not needed; 2) the sound source generator modules are in a mutually cancelling manner, rather than just one. Therefore, the obtained noise signal is only one signal, the influence of reverberant sound signals on post-processing analysis is avoided, and one-to-one noise reduction is really realized.

The laser displacement sensor 36 on the impeller 2 detects a range in each partition of the annular wall 12 of the volute 1 from the start position of entering the partition to the end of the partition according to when the impeller 2 is transferred to a certain partition range in the rotation process, the range is matched with the rotating speed data of the partition according to the displacement value interval, then the rotating speed data is transmitted to the signal analysis processing module 37, the frequency spectrum and phase parameters are extracted through the signal analysis processing module 37, the normalization and the extraction of the optimal reverse noise reduction sequence signal are carried out, and the distributed output is carried out to the noise reduction component.

In this embodiment, the number of active noise reduction assemblies corresponds to the number of partitions of the annular wall 12 of the volute 1, each active noise reduction assembly comprising at least two sound source generators, preferably loudspeakers. In the present embodiment, five sound source generators are used, including a first sound source generator 31, a second sound source generator 32, a third sound source generator 33, a fourth sound source generator 34, and a fifth sound source generator 35, the sound emission frequencies of the sound source generators are different from each other, and the first sound source generator 31: for eliminating spectrum noise in the frequency band of 100-300 Hz, the second sound source generator 32: the third sound source generator 33 is used for eliminating spectrum noise in a frequency band of 300-600 Hz: for eliminating the spectrum noise in the frequency band of 600-1000 Hz, the fourth sound source generator 34: for eliminating the spectrum noise in the frequency band of 1000-1400 Hz, the fifth sound source generator 35: the method is used for eliminating the spectrum noise in the 1400-2000 Hz frequency band.

The noise spectrum phase is higher at the position closer to the front cover 11 on the annular wall 12, and the spectrum phase is sequentially decreased along the molded line of the annular wall 12 in the clockwise direction. Therefore, in the first section Q1, the fifth sound source generator 35 and the fourth sound source generator 34 are close to the front cover 11, the third sound source generator 33 and the second sound source generator 32 are close to the rear cover, the first sound source generator 31 is located in the central region, and the fifth sound source generator 35, the fourth sound source generator 34, the second sound source generator 32 and the third sound source generator 33 are arranged clockwise (clockwise in fig. 2).

In the second partition Q2, the fifth sound source generator 35 and the fourth sound source generator 34 are close to the front cover 11, the third sound source generator 33 and the first sound source generator 31 are close to the rear cover, the second sound source generator 32 is located in the central area, and the fifth sound source generator 35, the fourth sound source generator 34, the first sound source generator 31 and the third sound source generator 33 are arranged clockwise.

In the third partition Q3, the fifth sound source generator 35 and the fourth sound source generator 34 are close to the front cover 11, the second sound source generator 32 and the first sound source generator 31 are close to the rear cover, the third sound source generator 33 is located in the central region, and the fifth sound source generator 35, the fourth sound source generator 34, the first sound source generator 31 and the second sound source generator 32 are arranged clockwise.

In the fourth section Q4, the fifth sound source generator 35 and the third sound source generator 33 are close to the front cover 11, the second sound source generator 32 and the first sound source generator 31 are close to the rear cover, the fourth sound source generator 34 is located in the central region, and the fifth sound source generator 35, the third sound source generator 33, the first sound source generator 31 and the second sound source generator 32 are arranged clockwise.

In the fifth partition Q5, the fourth sound source generator 34 and the third sound source generator 33 are close to the front cover 11, the second sound source generator 32 and the first sound source generator 31 are close to the rear cover, the fifth sound source generator 35 is located in the central area, and the fourth sound source generator 34, the third sound source generator 33, the first sound source generator 31 and the second sound source generator 32 are arranged clockwise.

The noise reduction method of the centrifugal fan comprises the following steps:

1) after the centrifugal fan normally operates for a certain time, such as 5s, the laser displacement sensor 36 on the impeller 2 starts to work;

2) when the laser displacement sensor 36 rotates with the impeller 2 to each of the five subareas, the laser displacement sensor 36 detects the distance x, which is different in each subarea from the annular wall 12, and the rotating speed r of the corresponding subarea is matched according to the actually measured distance x interval, such as the distance x1 e (34.7mm, 38.5 mm) in the first subarea Q1, the corresponding rotating speed range is r1 e (26r/s, 35 r/s), the distance x2 e (38.5mm, 69 mm) in the second subarea Q2, the corresponding rotating speed range is r2 e (35r/s, 75 r/s), the distance x3 e (69mm, 97 mm) in the third subarea Q3, the corresponding rotating speed range is r3 e (75r/s, 93 r/s), the distance x4 e in the fourth subarea Q4, the corresponding rotating speed range is r 4mm (97mm, r4 r, 106r/s ]; the matching relation between the distance x5 e (104mm, 187 mm) in the fifth sub-area Q5 and the corresponding rotating speed range is r5 e (106r/s, 150 r/s), the matching relation between the distance x and the rotating speed r can be stored in the laser displacement sensor 36 or the signal analysis processing module 37, in the embodiment, the laser displacement sensor 36;

3) the matched rotating speed is transmitted to the signal analysis processing module 37, and the signal analysis processing module 37 extracts corresponding noise frequency spectrums and phase parameters, so that noise frequency spectrums and phase parameters corresponding to the five partitions are obtained; in this step, according to the formula f ═ rZ/60, f is the noise frequency, wherein r is the rotating speed of the impeller, Z is the number of blades, and Z is determined after the centrifugal fan is manufactured, so that the frequency of the noise can be determined as long as the rotating speed r is determined, and the noise is subjected to FFT (Fourier transform analysis) analysis, so that the noise spectrum and the phase information can be obtained;

4) the signal analyzing and processing module 37 outputs an optimal reverse noise reduction sequence corresponding to the current noise spectrum and phase parameter of the corresponding partition to the noise reduction component in each partition, the signal analyzing and processing module 37 can perform signal processing modes commonly used in the prior art such as normalization and wavelet analysis on noise, then obtains a sound phase opposite to the processed noise, and obtains a noise reduction generation sequence of each sound source generator in each partition according to the frequency and phase parameter of the noise (the frequency, the phase and the position of each sound source generator are fixed, so that the situation of sound field cancellation between sound production of each sound source generator is known, and the sound source generator which produces sound can be controlled according to actual noise), thereby being capable of aiming at noise with more frequencies and phases;

Taking the first partition Q1 as an example, when the laser displacement sensor 36 on the impeller 2 starts to work normally, the current distance from the annular wall 12 is detected to be within the range of 34.7mm to 38.5mm, and then the corresponding rotating speed range is matched to be 26r/s to 35 r/s; and form a transmission signal and transmit the transmission signal to the signal analysis processing module 37, the signal analysis processing module 37 finds out a corresponding noise frequency spectrum and phase parameters according to the received rotation speed signal, and outputs an optimal reverse noise reduction sequence to the first sound source generator 31 and the second sound source generator 32 in the first partition Q1 after processing, and the two sound source generators emit noise reduction sound waves according to the received sound wave sequence signal.

Similarly, in the second sub-area Q2, when the laser displacement sensor 36 detects that the current distance from the ring wall 12 is within the range of 38.5mm to 69mm, the corresponding rotating speed range is matched to be 35r/s to 75r/s, and the corresponding rotating speed range is transmitted to the signal analysis module, the signal analysis module outputs a direction noise reduction sequence to the second sound source generator 32 and the third sound source generator 33 according to a series of analysis processing, and the two sound source generators emit sound wave noise reduction according to the received sound wave signals.

Claims

1. A centrifugal fan comprising a volute (1), an impeller (2) and a noise reducing device, the volute (1) comprising a circumferential wall (12) and a volute tongue (13), characterized in that: the annular wall (12) is divided into at least two partitions, the noise reduction device is an active noise reduction device, and the active noise reduction device comprises laser displacement sensors (36) arranged on the impeller (2) and noise reduction assemblies arranged in each partition and used for performing targeted noise reduction on noise in the corresponding partition according to displacement values detected by the laser displacement sensors (36).

2. The centrifugal fan of claim 1, wherein: the radius of curvature of the profile of the volute in each sector is the same.

3. The centrifugal fan of claim 2, wherein: taking a point at the volute tongue (13) as a starting point (O '), taking the center of the volute molded line as a circle center (O), taking a connecting line of the circle center (O) and the starting point (O') as a base line (L1) of the partition, clockwise rotating the base line (L1) around the circle center (O) for a certain angle to obtain a first partition line (L2), and taking a region between the base line (L1) and the first partition line (L2) as a first partition (Q1); the first partition line (L2) rotates clockwise around a circle center (O) by a certain angle to obtain a second partition line (L3), and the area between the first partition line (L2) and the second partition line (L3) is a second partition (Q2); the second partition line (L3) rotates clockwise around a circle center (O) by a certain angle to obtain a third partition line (L4), and the area between the second partition line (L3) and the third partition line (L4) is a third partition (Q3); the third partition line (L4) rotates clockwise around a circle center (O) by a certain angle to obtain a fourth partition line (L5), and the area between the third partition line (L4) and the fourth partition line (L5) is a fourth partition (Q4); the region between the fourth division line (L5) and the baseline (L1) is a fifth division (Q5).

4. The centrifugal fan of claim 1, wherein: the noise reduction assembly comprises at least two sound source generators, and the sound production frequencies of the sound source generators are different.

5. The centrifugal fan of claim 4, wherein: the sound source generators with higher frequency spectrum phase are arranged closer to the front cover (11) of the volute (1), and the frequency spectrum phase of the sound source generators is sequentially decreased along the clockwise direction of the molded line of the annular wall (12).

6. The centrifugal fan according to claim 4 or 5, wherein: the active noise reduction device also comprises a signal analysis processing module (37) which outputs a reverse noise reduction sequence signal to the noise reduction component according to the signal of the laser displacement sensor (36).

7. A range hood, its characterized in that: comprising a centrifugal fan according to any one of claims 1 to 6.

8. The noise reduction control method of the centrifugal fan according to claim 6, characterized in that: the method comprises the following steps:

1) after the centrifugal fan normally operates for a certain time, the laser displacement sensor (36) on the impeller (2) starts to work;

2) when the laser displacement sensor (36) rotates to each partition range along with the impeller (2), detecting the distance x between the laser displacement sensor and the annular wall (12), and matching corresponding rotating speed r for each different distance x;

3) the matched rotating speed is transmitted to a signal analysis processing module (37), and the signal analysis processing module (37) extracts the corresponding relation between the current rotating speed and the noise frequency spectrum and phase parameters;

4) the signal analysis processing module (37) outputs an optimal reverse noise reduction sequence corresponding to the current noise spectrum and phase parameter of the corresponding partition to the noise reduction assembly in each partition;

9. The noise reduction control method of the centrifugal fan according to claim 8, characterized in that: in the step 3), according to a formula f ═ rZ/60, f is the noise frequency, r is the rotating speed of the impeller, Z is the blade number of the impeller (2), the signal analysis processing module (37) determines the frequency of the noise according to the rotating speed r, and FFT analysis is carried out on the noise, so that the noise spectrum and the phase information are obtained.