Impedance-adjustable composite silencer

Abstract

The impedance-adjustable composite silencer comprises an air outlet pipeline connected with the air outlet end of an air supply tail end device, the air supply tail end device comprises a draught fan, the side wall of the air outlet pipeline is covered with a sound absorption layer, a Helmholtz resonator and an electric push rod are arranged outside the air outlet pipeline, and the electric push rod is connected with the draught fan. A hollow resonant cavity is formed in the Helmholtz resonator, a neck channel is communicated between the resonant cavity and the air outlet pipeline, an adjusting baffle used for adjusting and changing the cavity volume of the resonant cavity is slidably arranged at the end, away from the neck channel, of the resonant cavity, and a telescopic rod of the electric push rod is perpendicularly connected with the adjusting baffle. The telescopic adjusting direction of the electric push rods is distributed in the length direction of the Helmholtz resonators, the electric push rods are electrically connected with a control device, and the control device is electrically connected with a current sensor used for detecting the magnitude of current when the draught fan operates. According to the invention, low-frequency-to-high-frequency wide-frequency-domain noise reduction can be realized, and the method is especially suitable for residential air conditioner terminals with high noise requirements.

Description

Technical Field

[0001] This invention relates to the field of silencer technology, and more particularly to an adjustable impedance composite silencer. Background Technology

[0002] Currently, noise from the bedroom terminals of residential central air conditioning systems is a key issue affecting user comfort, with the main noise source being the fan. To reduce fan noise, silencers can be installed in the ventilation ducts. Common silencers fall into two main categories:

[0003] (1) Resistive silencer: Porous sound-absorbing materials (such as glass wool and rock wool) are arranged on the pipe wall or in the middle to consume sound energy by utilizing the sound resistance of the material itself. Resistive silencers have a wide noise reduction frequency range and are effective for mid-to-high frequency noise; however, resistive silencers are very poor at absorbing low-frequency noise (such as fan rotation noise and its harmonics); and, under long-term airflow scouring, porous sound-absorbing materials may produce debris or powder that spills out, thereby affecting indoor air quality and health.

[0004] (2) Reactive silencer: It uses the changes in the resonant structure or pipe cross-section to cause sound wave reflection and interference, thereby achieving the purpose of noise reduction. Taking the Helmholtz resonator as an example, it has high cleanliness and is highly targeted to low-frequency noise (resonant frequency); however, the Helmholtz resonator is less effective for noise outside the resonant frequency, and once it is manufactured, its resonant frequency cannot be changed, so it cannot adapt to the changes in rotational noise of the air conditioner fan when it is running at different speeds. Summary of the Invention

[0005] The purpose of this invention is to provide an adjustable impedance composite silencer that can achieve wide-range noise reduction from low frequency to high frequency. It is particularly suitable for residential air conditioning terminals with high noise requirements. It solves the problems of insufficient low-frequency noise reduction of traditional resistive silencers and the inability of fixed-frequency reactive silencers to adapt to changes in operating conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An adjustable impedance composite silencer includes an air outlet duct connected to the air outlet end of an air supply terminal device, the air supply terminal device including a fan, the sidewall of the air outlet duct being covered with a sound-absorbing layer, a Helmholtz resonator and an electric actuator being provided on the exterior of the air outlet duct at the end away from the air supply terminal device, the Helmholtz resonator having a hollow resonant cavity inside, a neck channel communicating between the resonant cavity and the air outlet duct, an adjusting baffle for adjusting and changing the cavity volume of the resonant cavity being slidably disposed at the end of the resonant cavity away from the neck channel, the telescopic rod of the electric actuator extending into the interior of the Helmholtz resonator and perpendicularly connected to the adjusting baffle, the telescopic adjustment direction of the electric actuator being distributed along the length direction of the Helmholtz resonator, the electric actuator being electrically connected to a control device, the control device being electrically connected to a current sensor for detecting the magnitude of the current during fan operation.

[0008] Furthermore, the sound-absorbing layer is located on the side wall of the air outlet duct between the air supply terminal device and the neck channel.

[0009] Furthermore, the thickness of the sound-absorbing layer is 4cm to 6cm.

[0010] Furthermore, the sound-absorbing layer includes polyester fiber sound-absorbing cotton and a metal mesh for fixing the surface of the polyester fiber sound-absorbing cotton.

[0011] Furthermore, the sound-absorbing layer is distributed in an outward convex shape, and the metal wire mesh located on the inner side of the sound-absorbing layer is aligned with the inner wall of the air outlet duct.

[0012] Furthermore, the length direction of the Helmholtz resonator is parallel to the airflow direction of the air outlet duct, the adjusting baffle is vertically distributed, and the outline shape of the adjusting baffle matches the vertical cross-sectional shape of the resonant cavity.

[0013] Furthermore, the Helmholtz resonator is located above the air outlet duct, and the electric push rod is placed on the upper side of the sound-absorbing layer.

[0014] Furthermore, the length of the neck channel is 4cm to 6cm, and the cross-sectional area of ​​the neck channel does not exceed 30cm². 2 .

[0015] Furthermore, the height of the resonant cavity does not exceed 15cm, and the cavity volume is not less than 14000cm³. 3 .

[0016] Furthermore, the air outlet duct is a square duct.

[0017] Compared with the prior art, the present invention provides an adjustable impedance composite silencer, which has the following beneficial effects:

[0018] (1) The present invention has impedance composite noise reduction function through the combination design of sound-absorbing layer and Helmholtz resonator, and achieves wide-band noise reduction. When the air supply terminal device blows out air, the noise in the mid-to-high frequency wide-band range is consumed and absorbed by the sound-absorbing layer, and the low-frequency fan rotation noise is absorbed by the Helmholtz resonator.

[0019] (2) The present invention designs an adjustable Helmholtz resonator combined with an electric push rod and an adjusting baffle. The electric push rod is linked with the fan of the air supply terminal device. The current of the fan is detected in real time by a current sensor. The position of the adjusting baffle is adjusted according to the fan speed (different speed levels correspond to different current levels) to change the cavity volume of the resonant cavity, thereby changing the resonant frequency of the Helmholtz resonator and coping with the low-frequency noise changes of the fan under different wind speed operating conditions.

[0020] (3) The overall structure height of the present invention does not exceed 50cm (including the air outlet duct), the overall structure is compact, and it does not require too much additional installation space.

[0021] (4) This invention can be applied to noise reduction treatment of air supply in residential bedrooms. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0024] Figure 2 This is a three-dimensional structural diagram of the present invention;

[0025] Figure 3 This is the control flowchart of the present invention.

[0026] Reference numerals: 1. Air supply terminal device; 11. Fan; 2. Air outlet duct; 3. Sound-absorbing layer; 31. Polyester fiber sound-absorbing cotton; 32. Metal wire mesh; 4. Helmholtz resonator; 41. Resonance cavity; 42. Neck channel; 5. Electric push rod; 6. Adjusting baffle; 7. Control device; 8. Current sensor. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature and the second feature are in direct contact, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] The present invention will now be described in further detail through detailed embodiments and in conjunction with the accompanying drawings.

[0032] Please refer to Figures 1-3One embodiment of the present invention provides an adjustable impedance composite silencer to achieve wide-band noise reduction and adapt to changes in low-frequency noise frequency by changing the resonant frequency. Specifically, the adjustable impedance composite silencer includes an air outlet duct 2 connected to the air outlet end of an air supply terminal device 1. The air supply terminal device 1 includes a fan 11. The sidewall of the air outlet duct 2 is covered with a sound-absorbing layer 3 for absorbing mid-to-high frequency wide-band noise. At the end of the air outlet duct 2 away from the air supply terminal device 1, a Helmholtz resonator 4 and an electric actuator 5 are provided for absorbing low-frequency fan rotation noise. The Helmholtz resonator 4 has a hollow resonant cavity 41 inside, and the resonant cavity 41 is connected to the air outlet duct 2. A neck channel 42 connects the resonant cavity 41 to the neck channel 42. An adjusting baffle 6, used to adjust the volume of the resonant cavity 41, is slidably installed at the end of the resonant cavity 41 away from the neck channel 42. The telescopic rod of the electric push rod 5 extends into the interior of the Helmholtz resonator 4 and is perpendicularly connected to the adjusting baffle 6. The telescopic adjustment direction of the electric push rod 5 is distributed along the length of the Helmholtz resonator 4. The electric push rod 5 is electrically connected to a control device 7, which is electrically connected to a current sensor 8 used to detect the magnitude of the current during the operation of the fan 11. The extension and retraction of the electric push rod 5 are controlled by the control device 7. The control device 7 issues action commands to the electric push rod 5 based on the real-time detection of the current during the operation of the fan 11 by the current sensor 8, thereby controlling the extension and retraction of the electric push rod 5 to change the position of the adjusting baffle 6, thus adjusting and changing the volume of the resonant cavity 41, achieving the purpose of changing the resonant frequency of the Helmholtz resonator 4, and thus adapting to the frequency changes of the fan rotation noise.

[0033] like Figure 1 As shown, when the air supply terminal device 1 blows air, the mid-to-high frequency broadband noise is consumed and absorbed by the sound-absorbing layer 3, while the low-frequency fan rotation noise is absorbed by the Helmholtz resonator 4. When the air supply speed of the air supply terminal device 1 changes, the current sensor 8 transmits the current signal of the fan 11 during operation to the control device 7. The control device 7 controls the electric push rod 5 to change the position of the adjusting baffle 6, thereby changing the cavity volume of the resonant cavity 41 and thus changing the resonant frequency of the Helmholtz resonator 4 to cope with the low-frequency noise changes of the fan 11 under different air speed operating conditions.

[0034] Specifically, as an example, the control device 7 can be a PLC controller module connected to a power supply. The air supply terminal device 1 is a fan-powered variable air volume terminal device, including a fan 11, and the air speed is changed by changing the frequency of the fan 11. Regarding the PLC controller module, the air supply terminal device 1, and the current sensor 8, their functions and structures are existing technologies, and commercially available products can be directly purchased. Those skilled in the art can select appropriate models according to their needs, so further details are omitted.

[0035] In some specific embodiments, such as Figure 1 and Figure 2 As shown, the sound-absorbing layer 3 is located on the side wall of the air outlet duct 2 between the air supply terminal device 1 and the neck channel 42. In this way, noise in the mid-to-high frequency broadband range can be fully consumed and absorbed.

[0036] In some specific embodiments, such as Figure 1 As shown, the sound-absorbing layer 3 includes polyester fiber sound-absorbing cotton 31 and a metal wire mesh 32 for fixing the surface of the polyester fiber sound-absorbing cotton 31.

[0037] refer to Figure 1 and Figure 2 Preferably, the sound-absorbing layer 3 protrudes outwards, and the metal mesh 32 located inside the sound-absorbing layer 3 is aligned with the inner wall of the air outlet duct 2. This ensures that the inner wall of the air outlet duct 2 is relatively flat and will not affect the air outlet.

[0038] Preferably, the thickness of the sound-absorbing layer 3 is 4cm to 6cm. The length of the neck channel 42 is 4cm to 6cm, and the cross-sectional area of ​​the neck channel 42 does not exceed 30cm². 2 The height of the resonant cavity 41 shall not exceed 15cm, and the cavity volume of the resonant cavity 41 shall not be less than 14000cm³. 3 In this way, we can ensure good noise reduction while making the overall structure more compact and reducing the installation space required.

[0039] As an example, the thickness of the sound-absorbing layer 3 can be set to 5cm. The length of the neck channel 42 is set to 5cm, the cross-sectional shape of the neck channel 42 is square, and the cross-sectional area is set to 25cm². 2 The height of resonant cavity 41 is 14 cm, and the cavity volume of resonant cavity 41 is 15400 cm³. 3 The air outlet duct 2 is a square duct with a cross-sectional length of 400mm and a cross-sectional width of 200mm.

[0040] In some specific embodiments, such as Figure 1 As shown, the length of the Helmholtz resonator 4 is parallel to the airflow direction of the outlet duct 2, and the adjusting baffle 6 is vertically oriented, with its outline matching the vertical cross-sectional shape of the resonant cavity 41. By designing the length of the Helmholtz resonator 4 to be parallel to the airflow direction of the outlet duct 2, the overall height can be reduced, making the overall structure more compact and requiring less additional installation space. Furthermore, the area of ​​the adjusting baffle 6 is the same as the vertical cross-sectional area of ​​the resonant cavity 41. The position of the adjusting baffle 6 can be controlled by the electric push rod 5, allowing adjustment and change of the cavity volume of the resonant cavity 41, thereby controlling and changing the resonant frequency of the Helmholtz resonator 4.

[0041] refer to Figure 1 and Figure 2 Preferably, the Helmholtz resonator 4 is located above the air outlet duct 2, and the electric push rod 5 is placed on the upper side of the sound absorption layer 3.

[0042] Reference Figure 3 Specifically, as an example, the air supply terminal device 1 has three wind speed operation modes (low wind speed, medium wind speed, and high wind speed), and the current magnitudes of the fan under different wind speed operation modes are preset (the preset current values are a1, b1, a2, b2, a3, b3 respectively, and the relationship of the current magnitudes is: a1 < b1 < a2 < b2 < a3 < b3). The control device 7 can determine the wind speed corresponding to the air supply terminal device 1 according to the current magnitude detected by the current sensor 8 during the operation of the fan 11, and issue a corresponding action instruction to the electric push rod 5.

[0043] For example, given the fan speed n (r / min) of the air supply terminal device 1 at different wind speeds, the frequency f of the rotational noise of the fan 11 is f = n / 60. Then, according to the formula the cavity volume V of the Helmholtz resonator 4 at this time is confirmed, and then the position of the adjusting baffle 6 is determined and the control logic of the control device 7 is formulated. Here, C is the speed of sound, S is the cross-sectional area of the neck channel 42, and L is the length of the neck channel 42. Among them, the three wind speed operation modes respectively correspond to three resonance cavities 41 with different cavity space sizes. The size of the Helmholtz resonator 4 can be designed in advance according to the specification parameters of the fan 11 used in the air supply terminal device 1, so as to be able to adjust and change the resonance frequency of the Helmholtz resonator 4 corresponding to different wind speed operation modes. Specifically, in the low wind speed operation mode, the current magnitude of the fan 11 is between a1 and b1, and a resonance cavity 41 with a larger cavity volume is required. The adjusting baffle 6 is located at the initial position correspondingly, that is, distributed near the electric push rod 5 in the resonance cavity 41; in the medium wind speed operation mode, the current magnitude of the fan 11 is between a2 and b2, and a resonance cavity 41 with a medium cavity volume is required. The adjusting baffle 6 is correspondingly moved to the middle position of the resonance cavity 41 for distribution; in the high wind speed operation mode, the current magnitude of the fan 11 is between a3 and b3, and a resonance cavity 41 with a smaller cavity volume is required. The adjusting baffle 6 is correspondingly moved to the limit position, that is, distributed at the end of the resonance cavity 41 far from the electric push rod 5. As Figure 1 shown, the limit position of the adjusting baffle 6 cannot exceed the position of the neck channel 42, that is, the movement range of the adjusting baffle 6 is to move and adjust in the space between the left end of the resonance cavity 41 and the neck channel 42. By changing the position of the adjusting baffle 6 in the resonance cavity 41, the cavity volume of the resonance cavity 41 can be changed, thereby changing the resonance frequency of the Helmholtz resonator 4 to cope with the low-frequency noise change of the fan 11 under different wind speed operation states.

[0044] The above embodiments are merely illustrative of the concept and technical solution of the present invention and are not intended to limit the present invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An adjustable impedance composite silencer, comprising an air outlet duct connected to the air outlet end of an air supply terminal device, wherein the air supply terminal device includes a fan, characterized in that, The sidewall of the air outlet duct is covered with a sound-absorbing layer. A Helmholtz resonator and an electric push rod are provided on the exterior of the air outlet duct at the end away from the air supply terminal device. The Helmholtz resonator has a hollow resonant cavity inside. A neck channel connects the resonant cavity to the air outlet duct. An adjusting baffle for adjusting the cavity volume of the resonant cavity is slidably provided at the end of the resonant cavity away from the neck channel. The telescopic rod of the electric push rod extends into the interior of the Helmholtz resonator and is perpendicularly connected to the adjusting baffle. The telescopic adjustment direction of the electric push rod is distributed along the length direction of the Helmholtz resonator. The electric push rod is electrically connected to a control device. The control device is electrically connected to a current sensor for detecting the magnitude of the current when the fan is running.

2. The adjustable impedance composite silencer according to claim 1, characterized in that, The sound-absorbing layer is located on the side wall of the air outlet duct between the air supply terminal device and the neck channel.

3. The adjustable impedance composite silencer according to claim 1, characterized in that, The thickness of the sound-absorbing layer is 4cm to 6cm.

4. The adjustable impedance composite silencer according to claim 1, characterized in that, The sound-absorbing layer includes polyester fiber sound-absorbing cotton and a metal mesh for fixing the surface of the polyester fiber sound-absorbing cotton.

5. The adjustable impedance composite silencer according to claim 4, characterized in that, The sound-absorbing layer is distributed in an outward convex shape, and the metal wire mesh located on the inner side of the sound-absorbing layer is aligned with the inner wall of the air outlet duct.

6. The adjustable impedance composite silencer according to claim 1, characterized in that, The length direction of the Helmholtz resonator is parallel to the airflow direction of the air outlet duct, the adjusting baffle is vertically distributed, and the outline shape of the adjusting baffle matches the vertical cross-sectional shape of the resonant cavity.

7. The adjustable impedance composite silencer according to claim 1 or 6, characterized in that, The Helmholtz resonator is located above the air outlet duct, and the electric push rod is placed on the upper side of the sound-absorbing layer.

8. The adjustable impedance composite silencer according to claim 1, characterized in that, The length of the neck channel is 4cm to 6cm, and the cross-sectional area of ​​the neck channel does not exceed 30cm². 2 .

9. The adjustable impedance composite silencer according to claim 1, characterized in that, The height of the resonant cavity shall not exceed 15 cm, and the cavity volume shall not be less than 14000 cm³. 3 .

10. The adjustable impedance composite silencer according to claim 1, characterized in that, The air outlet duct is a square duct.

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