阅读说明：本技术 抽油烟机的主动降噪装置及方法 (Active noise reduction device and method for range hood ) 是由 朱丽平 李彬 王重 叶磊 倪梓荣 于 2020-08-13 设计创作，主要内容包括：本发明公开了一种抽油烟机的主动降噪装置及方法。该装置包括安装在抽油烟机的下部的进气格栅处的第一噪声拾取部件、安装在抽油烟机的下端面上或下端面正下方中心位置的第二噪声拾取部件、安装在进气格栅下方且在抽油烟机的下端面上方的扬声器部件、以及控制器,其中,扬声器部件的喇叭朝向抽油烟机的前下方,第一噪声拾取部件、第二噪声拾取部件和扬声器部件与所述控制器连接。该方法包括：获取第一传递函数和第二传递函数；得到控制器的控制参数；得到控制器下次的输出信号。根据抽油烟机的结构形式及噪声产生机理设计抽油烟机的主动降噪装置和方法,充分发挥降噪系统的潜力,实现抽油烟机的空间降噪,提高噪声降低效果和降噪控制系统的稳定性。(The invention discloses an active noise reduction device and method of a range hood. The device comprises a first noise pickup part arranged at an air inlet grille at the lower part of the range hood, a second noise pickup part arranged on the lower end surface of the range hood or at the center position under the lower end surface, a loudspeaker part arranged below the air inlet grille and above the lower end surface of the range hood, and a controller, wherein a horn of the loudspeaker part faces the front lower part of the range hood, and the first noise pickup part, the second noise pickup part and the loudspeaker part are connected with the controller. The method comprises the following steps: acquiring a first transfer function and a second transfer function; obtaining control parameters of a controller; and obtaining the next output signal of the controller. The active noise reduction device and the method of the range hood are designed according to the structural form and the noise generation mechanism of the range hood, the potential of a noise reduction system is fully exerted, the spatial noise reduction of the range hood is realized, and the noise reduction effect and the stability of a noise reduction control system are improved.)

1. An active noise reduction device of a range hood, comprising a first noise pickup part installed at an air inlet grill of a lower portion of the range hood, a second noise pickup part installed at a central position on or right below a lower end surface of the range hood, a speaker part installed below the air inlet grill and above the lower end surface of the range hood, and a controller, wherein,

the loudspeaker of the loudspeaker component faces the front lower part of the range hood, and the first noise pickup component, the second noise pickup component and the loudspeaker component are connected with the controller.

2. The range hood active noise reduction device of claim 1, wherein the first noise pickup element comprises a microphone or an array of microphones.

3. The range hood active noise reduction device of claim 1, wherein the second noise pickup element comprises a microphone or an array of microphones.

4. The range hood active noise reduction device of claim 1, wherein the speaker component comprises a speaker and a resonant cavity.

5. The range hood active noise reduction device of claim 1, wherein the controller is mounted above the range hood.

6. A method of reducing noise in an active noise reduction device of a range hood according to any of claims 1 to 5, comprising:

under the condition that the loudspeaker component works alone, acquiring a first transfer function of sound output by the loudspeaker component to a first noise pickup component and a second transfer function of sound output by the loudspeaker component to a second noise pickup component;

under the condition that the range hood works independently, obtaining a control parameter of the controller according to the sound pressure signal measured by the first noise pickup component, the sound pressure signal measured by the second noise pickup component and the second transfer function;

and under the condition that the range hood and the loudspeaker component work simultaneously, obtaining the next output signal of the controller according to the current sound pressure signal measured by the first noise pickup component, the current output signal of the controller, the control parameter of the controller and the first transfer function so as to drive the loudspeaker component.

7. The noise reduction method according to claim 6, wherein the obtaining of the control parameter of the controller comprises:

obtaining the vibration speed of a virtual vibration surface of a sound source according to the sound pressure signal and the speed propagation factor picked up by the first noise pickup component;

obtaining a sound field corresponding to the lower end surface of the range hood according to the wave number conversion result of the sound pressure signal;

and obtaining the control parameters of the controller according to the vibration speed of the virtual vibration surface of the sound source, the sound field corresponding to the lower end surface of the range hood and the second transfer function.

8. The noise reduction method according to claim 6, wherein the obtaining of the output signal of the controller for the next time comprises:

obtaining a noise signal generated by the range hood according to the current sound pressure signal measured by the first noise pickup component, the current output signal of the controller and the first transfer function;

obtaining the vibration speed of a virtual vibration surface of a sound source according to a noise signal and a speed propagation factor generated by the range hood;

and obtaining the next output signal of the controller according to the vibration speed of the virtual vibration surface of the sound source and the control parameters of the controller.

9. A noise reduction method according to claim 7 or 8, wherein the range hood comprises an impeller of a fan and a volute, and the virtual vibration plane of the sound source is located on the plane of the center of the volute.

10. The noise reduction method of claim 6, further comprising:

and circularly executing to obtain the next output signal of the controller according to the current sound pressure signal measured by the first noise pickup component, the current output signal of the controller, the control parameter of the controller and the first transfer function so as to drive the loudspeaker component.

Technical Field

The invention relates to a plane acoustic holography technology, in particular to an active noise reduction device and method of a range hood.

Background

The motor noise and the pneumatic noise generated in the working process of the range hood seriously affect the experience effect of a user. The traditional method generally adopts sound absorption materials to match with a perforated plate to achieve the purpose of noise reduction, but the methods only have the effect on middle and high frequency noise, and the sound absorption materials are eroded by oil smoke along with the increase of the working time, so that the sound absorption effect is gradually deteriorated. And active noise reduction methods can be used to solve these problems.

Chinese patent publication No. CN107702171A discloses an active noise reduction method including controllers W1 and W2 and supporting input/output devices. However, the patent document does not give a specific arrangement application form on the range hood, so that the performance of the noise reduction system cannot be fully exerted. In addition, in the patent document, the signal collected by the noise collecting microphone is polluted by the sound wave generated by the speaker of the noise reduction system, although most of the sound wave generated by the noise reduction system can be subtracted through processing, the residual part still affects the noise reduction effect and the stability of the noise reduction system.

Chinese patent publication No. CN104534532A discloses an active noise reduction device for a range hood, which integrates an active noise reduction system inside a noise elimination pipeline, thereby increasing the versatility. However, as the oil smoke gas needs to enter the volute through the silencing pipeline to be discharged, and the loudspeaker and other components of the active noise reduction system are arranged in the silencing pipeline, the arrangement mode reduces the cross section of the airflow channel and increases the resistance, thereby influencing the oil smoke extraction effect of the range hood. And the loudspeaker faces downwards, so that the loudspeaker can be directly smoked by hot oil smoke in practical application, the performance of the loudspeaker is reduced, and the service life of the loudspeaker is prolonged.

Disclosure of Invention

The invention provides an active noise reduction device and method of a range hood, provides a specific active noise reduction device and method according to the structural form and the noise generation mechanism of the range hood, gives full play to the potential of a noise reduction system, and realizes global noise reduction in a sound field.

In order to solve the technical problems, the invention adopts the following technical scheme:

in one aspect, the invention provides an active noise reduction device for a range hood. The active noise reduction device of the range hood comprises a first noise pickup part arranged at an air inlet grille of the lower part of the range hood, a second noise pickup part arranged on the lower end surface of the range hood or at the center position under the lower end surface, a loudspeaker part arranged below the air inlet grille and above the lower end surface of the range hood, and a controller, wherein a horn of the loudspeaker part faces to the front lower part of the range hood, and the first noise pickup part, the second noise pickup part and the loudspeaker part are connected with the controller.

Optionally, for the active noise reduction device of the range hood, the first noise pickup component comprises a microphone or an array of microphones.

Optionally, for the active noise reduction device of the range hood, the second noise pickup component comprises a microphone or an array of microphones.

Optionally, for the active noise reduction device of the range hood, the speaker component comprises a speaker and a resonant cavity.

Optionally, for the active noise reduction device of the range hood, the controller is installed above the range hood, and the controller includes a filter circuit, an analog-to-digital conversion module, a digital signal processor, a digital-to-analog conversion module, and a power amplifier module.

On the other hand, the invention provides a noise reduction method of the active noise reduction device of the range hood. The noise reduction method of the active noise reduction device of the range hood comprises the following steps: under the condition that the loudspeaker component works alone, acquiring a first transfer function of sound output by the loudspeaker component to a first noise pickup component and a second transfer function of sound output by the loudspeaker component to a second noise pickup component; under the condition that the range hood works independently, obtaining a control parameter of the controller according to the sound pressure signal measured by the first noise pickup component, the sound pressure signal measured by the second noise pickup component and the second transfer function; and under the condition that the range hood and the loudspeaker component work simultaneously, obtaining the next output signal of the controller according to the current sound pressure signal measured by the first noise pickup component, the current output signal of the controller, the control parameter of the controller and the first transfer function so as to drive the loudspeaker component.

Optionally, for the noise reduction method, the obtaining of the control parameter of the controller includes: obtaining the vibration speed of a virtual vibration surface of a sound source according to the sound pressure signal and the speed propagation factor picked up by the first noise pickup component; obtaining a sound field corresponding to the lower end surface of the range hood according to the wave number conversion result of the sound pressure signal; and obtaining the control parameters of the controller according to the vibration speed of the virtual vibration surface of the sound source, the sound field corresponding to the lower end surface of the range hood and the second transfer function.

Optionally, for the noise reduction method, the obtaining an output signal of the controller for the next time includes: obtaining a noise signal generated by the range hood according to the current sound pressure signal measured by the first noise pickup component, the current output signal of the controller and the first transfer function; obtaining the vibration speed of a virtual vibration surface of a sound source according to a noise signal and a speed propagation factor generated by the range hood; and obtaining the next output signal of the controller according to the vibration speed of the virtual vibration surface of the sound source and the control parameters of the controller.

Optionally, for the noise reduction method, the range hood includes an impeller of a fan and a volute, and the virtual vibration plane of the sound source is located on a plane where a center of the volute is located.

Optionally, the noise reduction method further comprises: and circularly executing to obtain the next output signal of the controller according to the current sound pressure signal measured by the first noise pickup component, the current output signal of the controller, the control parameter of the controller and the first transfer function so as to drive the loudspeaker component.

Compared with the prior art, the technical scheme of the invention has the following main advantages:

1. the active noise reduction device and method for the range hood provided by the embodiment of the invention adopt a plane acoustic holography technology, assume that noise generated by the range hood is radiated outwards through an air inlet grille, and predict the distribution of a virtual vibration surface in the range hood and a sound field in the front and the lower part in real time according to noise signals picked up by a noise pickup component at the air inlet grille.

2. And finishing the design of the controller according to the predicted sound source information and sound field information, and ensuring the stability of the system.

3. The installation direction of the loudspeaker component faces to the front lower part of the range hood, so that the noise control effect of a target area can be improved, and the influence of noise emitted by the loudspeaker component on the noise pickup component can be reduced.

4. The active noise reduction device and the method of the range hood are designed according to the structural form and the noise generation mechanism of the range hood, the potential of a noise reduction system is fully exerted, the spatial noise reduction of the range hood is realized, and the noise reduction effect and the stability of a noise reduction control system are improved.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 is a front view of an active noise reduction device of a range hood according to an embodiment of the present invention;

FIG. 2 is a cross-sectional side view A-A of the active noise reducer of the range hood of FIG. 1;

fig. 3 is a flowchart of a noise reduction method of the active noise reduction device of the range hood shown in fig. 1 according to another embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Fig. 1 is a front view of an active noise reduction device of a range hood according to an embodiment of the present invention. Figure 2 is a cross-sectional side view a-a of the active noise reducer of the range hood shown in figure 1. As shown in fig. 1 and 2, the active noise reduction device of the hood according to this embodiment includes a first noise pickup part 110 installed at an intake grill of a lower portion of the hood, a second noise pickup part 120 installed at a central position on or just below a lower end surface 150 of the hood, a speaker part 130 installed below the intake grill and above the lower end surface of the hood, and a controller 140. Wherein, the loudspeaker of the loudspeaker component 130 faces the front lower part of the range hood. The first noise pickup part 110, the second noise pickup part 120, and the speaker part 130 are connected to the controller 140. The hood is, for example, a tower hood.

The first noise pickup part 110 is used to measure noise radiated downward from the hood through the intake grill and may include a microphone or a microphone array. As an alternative embodiment, the microphone array is arranged at the air inlet grille of the range hood and is positioned on the same plane.

The second noise pickup assembly 120 is used for off-line calibration of the sound field and may include a microphone or a microphone array. As an alternative embodiment, the microphone array is arranged at the center position right below the lower end face of the range hood. The off-line calibration refers to that the controller 140 drives the speaker component 130 to make a sound and calculates the corresponding transfer function H under the condition that the range hood does not work₁And H₂. After calibration is completed, the second noise pickup part 120 can be removed, so that only the first noise pickup part 110 arranged at the air inlet grille below the range hood is left, and the influence on the oil smoke extraction effect of the range hood is avoided.

The speaker assembly 130 is used to generate anti-noise sound waves to cancel the noise of the original sound field of the target area, and may include a speaker and a resonant cavity.

The controller 140 can be installed above the range hood to avoid interference and erosion of the controller 140 by hot oil smoke. The controller 140 may include a filter circuit, an analog-to-digital conversion module, a digital signal processor, a digital-to-analog conversion module, and a power amplifier module.

The range hood may include an impeller of a fan and a volute 160 that, during operation, creates suction that draws cooking fumes in through an underlying air intake grill and out through a flue.

The installation direction of the speaker part 130 faces the front lower part of the range hood, which can not only improve the noise control effect of the target area, but also reduce the influence of the noise emitted by the speaker part 130 on the first noise pickup part 110. The spatial installation positions of the first noise pickup part 110 and the second noise pickup part 120, and the speaker part 130 are shown in fig. 1 and 2, wherein the first noise pickup part 110 picks up a noise signal as an input of the controller 140, and it is required to ensure that the influence of the sound emitted from the speaker part 130 on it is minimized; and the second noise pickup part 120 picks up a noise signal as feedback information of the controller 140, requiring that the sound emitted from the speaker part 130 can effectively reach the area. Because the sound emitted by the loudspeaker component 130 has directivity, the loudspeaker component 130 is arranged towards the front lower part of the range hood, so that the opposite-phase sound wave emitted by the loudspeaker component 130 can be concentrated on the front lower part of the range hood, namely a noise reduction target area; at this time, the proportion of the reverse-phase sound wave reaching the first noise pickup element 110 is small, and therefore, the influence thereon is reduced, and the stability of the noise reduction control system is improved.

Fig. 3 is a flowchart of a noise reduction method of the active noise reduction device of the range hood according to another embodiment of the present invention.

As shown in fig. 3, in step S310, in the case where the speaker section 130 operates alone, a first transfer function where the sound output from the speaker section 130 reaches the first noise pickup section 110 and a second transfer function where the sound reaches the second noise pickup section 120 are acquired.

When the hood is turned off and the speaker unit operates alone, the controller 140 generates a driving signal to make the speaker unit 130 emit a sound, which may beAs a white noise signal or a swept frequency signal. A first transfer function H between the output of the speaker section 130 to the first noise pickup section 110 is identified separately₁And a second transfer function H between the output of the speaker section 130 to the second noise pickup section 120₂. The sound signal output from the speaker unit 130 is picked up by the first noise pickup unit 110 and the second noise pickup unit 120 and then transmitted back to the controller 140, and the input signal and the response signal corresponding to a system are known, and the transfer function H can be identified according to the relationship between the input signal and the response signal₁And H₂. The second noise pick-up component 120 may be removed after the transfer function identification is complete. Since active noise reduction is based on the principle of sound wave superposition, the sound emitted from the speaker component 130 must have the characteristics of similar amplitude and opposite phase with the original noise in the target noise reduction region after reaching the target noise reduction region. Thus, the first transfer function H between the sound signal emitted by the speaker section 130 and the first noise pickup section 110₁And a second transfer function H to the second noise pick-up element 120₂Must be accurately identified, the two transfer functions H₁And H₂Including amplitude and phase information of the transfer path.

In step S320, when the range hood operates alone, a control parameter of the controller is obtained according to the sound pressure signal measured by the first noise pickup part 110, the sound pressure signal measured by the second noise pickup part 120, and the second transfer function.

Step S320 may specifically include the following steps:

in the first step, the first noise pickup element 110 picks up the sound pressure signal and performs wave number conversion in the x and y directions on the plane to obtain a wave number conversion result of the sound pressure signal. In the case where the range hood is operated alone, that is, the range hood is connected to the flue to be normally operated, and the speaker part 130 is not operated, the noise signal p (x, y, z) of the plane where the grill is located is picked up by the first noise pickup part 110_h) And performing wave number conversion in x and y directions on the plane to obtain P (k)_x,k_y,z_h). Here, k_xAnd k_yRespectively representing sound waves in the airProjection of the number k (k ═ angular frequency/speed of sound) in the x and y directions, z_hThe distance in the vertical direction from the first noise pickup 110 to the centre plane of the fan is indicated as R1 in fig. 2.

Second, a result P (k) of wave number conversion based on the sound pressure signal_x,k_y,z_h) And a velocity propagation factor to obtain a virtual vibration plane z of the sound source_oThe vibration speed of (2). Wherein, the virtual vibration plane of the sound source can be located on the plane of the center of the volute. Since most of the noise radiated outside by the hood installed in the flue is radiated through the lower end surface 150, it is assumed that the noise generated by the hood is generated from the virtual vibration plane z of a sound source_oGenerated, the virtual vibration plane z_oLocated near the plane of the center of the volute and then in turn passing through the plane z of the first noise pickup element 110_hAnd a plane z in which the lower end surface 150 of the hood and the second noise pickup part 120 are located_sAnd then is transmitted out. Wherein the lower end surface 150 and the plane z of the second noise pickup part 120 are located_sThey may or may not coincide. At the lower end surface 150 and the plane z where the second noise pickup part 120 is located_sWhen the misalignment occurs, the distance in the vertical direction needs to be within 10 mm. Virtual vibration plane z_oThe vibration speed of (c) can be obtained by the following equation:

here, the first and second liquid crystal display panels are,

and

respectively representing inverse wave number conversion of the expression in x and y directions; g (k)_x,k_y,z_h-z_o) Is a velocity propagation factor, which is defined as:

representing two planesAnd (3) the relationship between the inter-sound pressure and the vibration speed of the sound medium, wherein rho, c and k respectively represent the air density, the propagation speed of sound in the air and the sound wave number, e is a natural base number, and i is an imaginary number unit. In the expression, rho, c, k, z_h、z_sAre known, and velocity propagation factors can be calculated by substituting the relevant parameters.

Third, the result P (k) is converted from the wave number of the sound pressure signal_x,k_y,z_h) A sound field corresponding to the lower end surface 150 of the range hood is obtained. The lower end surface 150 of the range hood corresponds to a sound field:

here, e is a natural base number, and i is an imaginary unit.

The fourth step is to obtain the vibration speed v (x, y, z) of the virtual vibration plane of the sound source according to the above steps_oT), sound field p (x, y, z) corresponding to lower end surface 150 of range hood_sT), and a second transfer function H₂The control parameter C of the controller 140 is obtained. Based on the results of the above measurement calculations, the control parameter C of the design controller 140 has the following expression:

C＝F_ω[v(x,y,z_o,t)]/F_ω[p(x,y,z_s,t)]/H₂(3)

here, t represents the current time, H₂Representing a second transfer function, F, between the sound signal emitted by the loudspeaker component 130 and the second noise pick-up component 120_ωRepresenting a fourier transform.

In step S330, when the hood and the speaker part 130 are simultaneously operated, the next output signal of the controller 140 is obtained according to the current sound pressure signal measured by the first noise pickup part 110, the current output signal of the controller 140, the control parameter of the controller 140, and the first transfer function, so as to drive the speaker part 130.

Step S330 may specifically include the following steps:

first, the controller 140 is designed according to the aboveThe time extraction controller 140 inputs a sound pressure signal. Specifically, the current sound pressure signal measured by the first noise pickup part 110, the current output signal of the controller 140, and the first transfer function H₁And obtaining a noise signal generated by the range hood:

p_in(x,y,z_h,t)＝p(x,y,z_h,t)-y(t)*H₁(4)

in formula (4), p (x, y, z) represents a linear convolution_hT) is the sound pressure signal measured in real time by the first noise pickup element 110, indicating that the current time t is at z_hSound pressure measured at each point on the plane; y (t) is an output signal of the controller 140, which is a driving signal of the speaker part 130 generated by the controller 140; h₁Is a first transfer function between the sound signal emitted from the speaker part 130 and the first noise pickup part 110, and these three quantities are known, and the input sound pressure signal p of the controller 140 can be obtained by substituting the formula (4)_in(x,y,z_hT). The noise signal p of the original sound field is extracted from the noise signal picked up by the first noise pickup section 110 by the formula (4)_in(x,y,z_hAnd t) is a noise signal generated by the hood itself to the controller 140.

And secondly, obtaining the vibration speed of the virtual vibration surface of the sound source according to the noise signal and the speed propagation factor generated by the range hood. The calculation result of the formula (4) is converted by wave number and then is substituted into the formula (5), and then the virtual vibration surface z of the sound source is obtained_oThe vibration speed of (2) is as follows:

and thirdly, obtaining a next output signal of the controller 140 according to the vibration speed of the virtual vibration plane of the sound source and the control parameter of the controller. The control parameter C of the controller 140 obtained in the formula (5) and the formula (3) is substituted into the formula (6), and the next output signal of the controller 140 can be obtained.

y(t)＝v_in(x,y,z_o,t)*C (6)

In equation (6), the signal output by the controller 140 is played through the speaker unit 130 to reach the target noise reduction region, and the signal is cancelled with the noise in the target noise reduction region.

Step S330 may be repeatedly and cyclically performed continuously to generate anti-noise sound waves, thereby reducing the noise radiated outward by the range hood. Since the control parameters of the controller 140 are obtained by off-line measurement and calculation, the sound waves generated by the active noise reduction device itself do not destroy the stability of the noise reduction control system. Here, offline means that the control parameter C of the controller 140 is calculated in advance in a case where the active noise reduction device is not operated.

The active noise reduction device and the method for the range hood provided by the embodiment of the invention are designed according to the structural form and the noise generation mechanism of the range hood, so that the potential of a noise reduction system is fully exerted, the spatial noise reduction of the range hood is realized, and the noise reduction effect is improved. The installation direction of the loudspeaker component faces the front lower part of the range hood, so that the noise control effect of a target area can be improved, and the influence of noise emitted by the loudspeaker component on the first noise pickup component can be reduced. Only the noise pickup part is arranged at the air inlet grille below the range hood, so that the influence on the oil fume extraction effect of the range hood is avoided.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the claims, and all equivalent structures or equivalent processes that are transformed by the content of the specification and the drawings, or directly or indirectly applied to other related technical fields are included in the scope of the claims.