A multi-parameter controlled frequency-adjustable micro-slit plate sound absorption structure

Abstract

The application discloses a frequency-adjustable micro-slit plate sound absorption structure with multi-parameter control, which comprises a fixed micro-slit plate (1), a movable micro-slit plate (2), a sound absorption back cavity and a rotating rod (5). The rotating rod (5) drives the movable bottom plate (4) to rotate, and at the same time, the movable bottom plate (4) moves along the axial direction inside the main cavity body (3) to adjust the depth of the sound absorption back cavity. When the rotating rod (5) drives the movable micro-slit plate (2) to rotate, the cross-sectional area of the micro-channel between the fixed micro-slit plate (1) and the movable micro-slit plate (2) is changed, so that the slitting rate of the movable micro-slit plate (2) is adjusted. The frequency-adjustable sound absorption structure has simple control mode, wide frequency adjustment range and good application prospect in a specific periodic noise environment.

Description

Technical Field

[0001] This invention relates to the field of mechanically adjustable frequency-tunable sound-absorbing structures, specifically a frequency-tunable micro-slit plate sound-absorbing structure with multi-parameter control. Background Technology

[0002] Noise control standards for large-scale equipment in industries such as manufacturing, construction, and transportation are becoming increasingly stringent. Furthermore, the noise from such equipment significantly impacts its concealment and precision, making noise control a crucial and pressing issue in equipment noise reduction projects. Simultaneously, the increasing size of equipment, the proliferation of noise sources, and the shift towards lower-frequency and wider-bandwidth noise all present new challenges for noise control.

[0003] Currently, passive noise reduction is mainly achieved by using sound-absorbing materials or structures. Utilizing resonant sound-absorbing structures to control and absorb noise from large equipment is a simple, effective, and widely used method.

[0004] However, this approach also presents new challenges: low-frequency noise has longer sound waves, usually requiring a thicker sound-absorbing structure to achieve effective sound absorption; broadband noise typically requires multiple sound-absorbing units with different resonant frequencies to be connected in parallel, so that the whole structure can effectively absorb sound across multiple frequency bands. The aforementioned design methods undoubtedly increase the size of the sound-absorbing structure, further enhancing the design and optimization difficulties in noise control within confined spaces.

[0005] Furthermore, a wide-bandwidth noise environment does not mean that the instantaneous noise amplitude is high across the entire frequency range. Especially for large equipment whose power source outputs power at a specific speed, the frequency corresponding to the main noise amplitude changes periodically with the operating conditions (at a certain speed). Targeting the main noise frequency with sound absorption can effectively control noise, which leads to another bottleneck faced by resonant sound-absorbing structures—the strong selectivity of sound absorption. The resonant frequency of a sound-absorbing structure is determined by its structural parameters; therefore, once the structural parameters are fixed, its sound absorption range and capacity are also fixed, resulting in poor adaptability. Summary of the Invention

[0006] The purpose of this invention is to provide a frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control, including a fixed micro-slit plate, a movable micro-slit plate, a sound-absorbing back cavity, and a rotating rod;

[0007] The fixed micro-slit plate is sealed at the upper open position of the sound-absorbing back cavity;

[0008] The movable micro-slit plate is placed below the fixed micro-slit plate and is located inside the sound-absorbing back cavity;

[0009] The movable micro-slit plate is connected to the rotating rod via a slot;

[0010] The sound-absorbing back cavity is an open cavity at the top, including a main cavity body and a movable bottom plate;

[0011] The main cavity is a hollow cavity with openings at both ends;

[0012] The movable base plate is connected to the bottom end of the main cavity and can move along the axial direction of the main cavity;

[0013] The movable base plate is connected to the rotating rod via a slot;

[0014] The rotating rod is rotatable, and when it rotates, it drives the movable base plate and the movable micro-slit plate to rotate synchronously.

[0015] While the rotating rod drives the movable base plate to rotate, the movable base plate moves axially inside the main cavity to adjust the depth of the sound-absorbing back cavity.

[0016] When the rotating rod drives the moving micro-slit plate to rotate, it changes the cross-sectional area of ​​the microchannel between the fixed micro-slit plate and the moving micro-slit plate, thereby adjusting the opening rate of the moving micro-slit plate.

[0017] Furthermore, when the opening rate of the moving micro-slit plate decreases, the depth of the sound-absorbing back cavity increases.

[0018] Furthermore, the main cavity has threads with the same parameters as the outer end of the movable base plate.

[0019] Furthermore, the direction of movement of the movable base plate is determined by the direction of the thread rotation, and the movement speed is determined by the thread pitch.

[0020] Furthermore, multiple annular micro-slits are distributed on the fixed micro-slit plate and the moving micro-slit plate.

[0021] Furthermore, the upper half of the fixed micro-slit plate is uniformly distributed with multiple annular micro-slits, and the radius of these annular micro-slits shows an increasing trend.

[0022] The upper and lower halves of the moving micro-slit plate are evenly distributed with multiple annular micro-slits, and the radius of these annular micro-slits increases in an increasing trend.

[0023] Among them, the angle between the two ends of the annular micro-slit in the upper half of the moving micro-slit plate and the center is greater than the angle between the two ends of the annular micro-slit in the lower half and the center.

[0024] Furthermore, the fixed micro-slit plate and the moving micro-slit plate are arranged coaxially in a micro-slit ring, and the sound waves formed by the overlapping part of the two micro-slits enter the micro-channel of the sound-absorbing back cavity.

[0025] Furthermore, when the moving micro-slit plate rotates, the microchannel exists in the following three states:

[0026] 1) The micro-slits of the fixed micro-slit plate only overlap with the micro-slits of the upper half of the moving micro-slit plate;

[0027] 2) The micro-slits of the fixed micro-slit plate only overlap with the micro-slits of the lower half of the moving micro-slit plate;

[0028] 3) The micro-slits of the fixed micro-slit plate overlap with the micro-slits of the upper and lower parts of the moving micro-slit plate;

[0029] The slit width parameter of the microchannel differs depending on the three different conditions.

[0030] Furthermore, the opening rate changes periodically with 360° as the moving micro-slit plate rotates.

[0031] The technical effects of this invention are undeniable. This invention mainly solves the problems of strong selectivity and poor adaptability of passive resonant sound-absorbing structures.

[0032] Based on the structural parameter control rules of the micro-slit plate composite structure, this invention designs an innovative frequency-adjustable micro-slit plate sound absorption structure. This structure can independently control the two main structural parameters: the opening ratio and the back cavity depth. When in the above-mentioned situation 3, the proportion of different slit widths (i.e., the proportion of different slit widths provided by the moving micro-slit plate 2 in the microchannel) can be controlled to a certain extent.

[0033] This invention enables the adjustment of the resonant frequency of a sound-absorbing structure, while ensuring that it has good sound absorption performance.

[0034] This invention achieves frequency adjustment from 250 to 1430 Hz and resonant frequency offset of 1180 Hz through the coordinated control of two parameters.

[0035] The frequency-adjustable sound-absorbing structure described in this invention has a simple control mode, a wide frequency tuning range, and good application prospects in specific periodic noise environments. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a frequency-tunable micro-slit plate sound-absorbing structure.

[0037] Figure 2 The sound absorption coefficient curve is obtained by rotating the rotor from its initial state to 180° in 15° increments.

[0038] Figure 3 The sound absorption coefficient curve is shown after the rotor has rotated 10 times in 360° steps from its initial state.

[0039] Figure 4 The sound absorption coefficient curve is obtained after the rotor has been rotated 10 times in 375° increments from its initial state.

[0040] In the diagram: Fixed micro-slit plate 1, movable micro-slit plate 2, main cavity body 3, movable base plate 4, and rotating rod 5. Detailed Implementation

[0041] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0042] Example 1:

[0043] See Figures 1 to 4 A frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control includes a fixed micro-slit plate 1, a movable micro-slit plate 2, a sound-absorbing back cavity, and a rotating rod 5.

[0044] The fixed micro-slit plate 1 is sealed at the open position at the upper end of the sound-absorbing back cavity;

[0045] The movable micro-slit plate 2 is placed below the fixed micro-slit plate 1 and is located inside the sound-absorbing back cavity;

[0046] The movable micro-slit plate 2 is connected to the rotating rod 5 via a slot;

[0047] The sound-absorbing back cavity is an open cavity at the top, including the main cavity body 3 and the movable bottom plate 4;

[0048] The main cavity 3 is a hollow cavity with openings at both ends;

[0049] The movable base plate 4 is connected to the bottom end of the main cavity 3 and can move along the axial direction of the main cavity 3;

[0050] The movable base plate 4 is connected to the rotating rod 5 via a slot;

[0051] The rotating rod 5 is rotatable, and when it rotates, it drives the movable base plate 4 and the movable micro-slit plate 2 to rotate synchronously.

[0052] While the rotating rod 5 drives the movable base plate 4 to rotate, the movable base plate 4 moves axially inside the main cavity 3 to adjust the depth of the sound-absorbing back cavity.

[0053] When the rotating rod 5 drives the moving micro-slit plate 2 to rotate, it changes the cross-sectional area of ​​the microchannel between the fixed micro-slit plate 1 and the moving micro-slit plate 2, thereby adjusting the opening rate of the moving micro-slit plate 2.

[0054] When the opening ratio of the moving micro-slit plate 2 decreases, the depth of the sound-absorbing back cavity increases.

[0055] The main cavity 3 has threads with the same parameters inside as the movable base plate 4 at its outer end.

[0056] The direction of movement of the movable base plate 4 is determined by the direction of the thread, and the speed of movement is determined by the thread pitch.

[0057] The fixed micro-slit plate 1 and the moving micro-slit plate 2 are provided with multiple annular micro-slits.

[0058] The upper half of the fixed micro-slit plate 1 has a plurality of annular micro-slits evenly distributed, and the radius of these annular micro-slits shows an increasing trend.

[0059] The upper and lower halves of the moving micro-slit plate 2 are evenly distributed with multiple annular micro-slits, and the radius of these annular micro-slits shows an increasing trend.

[0060] Among them, the angle between the two ends of the annular micro-slit in the upper half of the moving micro-slit plate 2 and the center is greater than the angle between the two ends of the annular micro-slit in the lower half and the center.

[0061] The fixed micro-slit plate 1 and the movable micro-slit plate 2 are arranged coaxially in a micro-slit ring, and the sound waves formed by the overlapping part of the two micro-slits enter the micro-channel of the sound-absorbing back cavity.

[0062] When the moving micro-slit plate 2 rotates, the microchannel exists in the following three situations:

[0063] 1) The micro-slits of the fixed micro-slit plate 1 overlap only with the micro-slits of the upper half of the moving micro-slit plate 2;

[0064] 2) The micro-slits of the fixed micro-slit plate 1 overlap only with the micro-slits of the lower half of the moving micro-slit plate 2;

[0065] 3) The micro-slits of the fixed micro-slit plate 1 overlap with the micro-slits of the upper and lower parts of the moving micro-slit plate;

[0066] The slit width parameter of the microchannel differs depending on the three different conditions.

[0067] The opening ratio changes periodically with 360° as the moving micro-slit plate 2 rotates.

[0068] Example 2:

[0069] See Figures 1 to 4 A frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control includes a fixed micro-slit plate 1, a movable micro-slit plate 2, a main cavity body 3, a movable base plate 4, and a rotating rod 5.

[0070] The main cavity 3 and the movable bottom plate 4 form a sound-absorbing back cavity;

[0071] The fixed micro-slit plate 1 is sealed at the upper opening of the sound-absorbing back cavity; the movable micro-slit plate 2 is placed below the fixed micro-slit plate 1 and is inside the back cavity.

[0072] Both the movable micro-slit plate 2 and the movable base plate 4 are connected to the rotating rod 5 via slots.

[0073] The micro-slits on both the fixed micro-slit plate 1 and the movable micro-slit plate 2 are annular.

[0074] The microslits on the fixed microslit plate 1 are arranged in a 180° ring on the upper half of the plate, with the ring radius increasing from 10 to 25 mm, and the width of each microslit being 0.5 mm. The microslits on the movable microslit plate 2 are also ring-shaped, with the upper half being a 180° ring and the lower half a 35° ring. The ring radius of the upper half increases from 10 to 25 mm, and the width of the microslit is 0.2 mm. The ring radii of the lower half are 10 and 15 mm respectively, and the width of the microslit is 0.5 mm.

[0075] The main cavity 3 has threads with the same parameters on its interior and the movable base plate 4 on its outer end, allowing for mechanical mating.

[0076] The fixed micro-slit plate 1 and the movable micro-slit plate 2 are arranged coaxially in a micro-slit ring, and the sound waves formed by the overlapping part of the micro-slits of the two enter the micro-channel of the sound-absorbing back cavity.

[0077] When the rotating rod 5 rotates, the movable micro-slit plate 2 and the movable base plate 4 rotate synchronously.

[0078] The area of ​​the microchannel can be changed by rotating the micro-slit plate 2 driven by the rotating rod 5, so as to increase or decrease the opening rate.

[0079] As the rotating rod 5 rotates, it drives the movable base plate 4 to rotate. Simultaneously, the movable base plate 4 moves axially within the main cavity 3 to increase or decrease the depth of the sound-absorbing back cavity. The direction of movement of the movable base plate 4 is determined by the thread direction, and the movement speed is determined by the thread pitch.

[0080] The rotation of the rotating rod 5 simultaneously causes two changes to the structure. First, it alters the opening ratio of the micro-slit plate; second, it changes the depth of the sound-absorbing back cavity. The trend for both is that as the opening ratio decreases, the depth of the sound-absorbing back cavity increases.

[0081] The maximum opening rate is the opening rate corresponding to the overlap of the upper half of the circumferential seam of the moving micro-seam plate 2 and the fixed micro-seam plate 1. The opening rate gradually decreases as the moving micro-seam plate 2 rotates.

[0082] The opening ratio changes with the rotation of the moving micro-slit plate 2 in a 360° cycle, and the depth of the sound-absorbing back cavity moves only according to the direction of rotation. Therefore, the relationship between the depth of the sound-absorbing back cavity and the rate of change of the opening ratio can be adjusted as needed.

[0083] Under special circumstances, a third type of structural parameter change may occur locally. When the rotating angle of the moving micro-slit plate 2 is within different ranges, the composition of the microchannel will exhibit three different situations:

[0084] 1) The micro-slits of the fixed micro-slit plate 1 only overlap slightly with the micro-slits of the upper half of the moving micro-slit plate 2.

[0085] 2) The micro-slits of the fixed micro-slit plate 1 only overlap significantly with the micro-slits of the lower half of the moving micro-slit plate 2.

[0086] 3) As a transitional stage from 1 to 2, the micro-slits of the fixed micro-slit plate 1 overlap with the micro-slits of the upper and lower parts of the moving micro-slit plate. Furthermore, the opening rate changes with rotation within the three case ranges, and the slit width parameter of the microchannel changes with the three cases.

[0087] Example 3:

[0088] The method for controlling the opening rate of the frequency-adjustable micro-slit sound-absorbing structure is as follows:

[0089] Manually control the position of the movable base plate to achieve a sound-absorbing back cavity depth of 50mm, with the upper half of the micro-slits of the fixed and movable micro-slit plates completely overlapping, as the initial state. Connect the movable base plate and the movable micro-slit plate via a slot using a rotating rod.

[0090] like Figure 2 The diagram shows the sound absorption coefficient curve as the rotor rotates from its initial state to 180° in 15° increments. As the rotor rotates, the microchannel area formed by the fixed and movable micro-slit plates gradually decreases, i.e., the slit ratio decreases. This causes the sound absorption frequency of the micro-slit plate sound-absorbing structure to shift to lower frequencies. Since the thread pitch between the movable base plate and the main cavity is 4.8mm, a 180° rotation only causes a 2.4mm change in the sound-absorbing back cavity depth. This embodiment mainly illustrates the control of the slit ratio; therefore, the frequency change caused by the back cavity depth is temporarily ignored. By controlling the slit ratio, an adjustment range of approximately 280-680Hz is achieved, and the resonant frequency can be shifted by 400Hz.

[0091] Example 4:

[0092] The method for controlling the depth of the sound-absorbing back cavity in a frequency-adjustable micro-slit plate sound-absorbing structure is as follows:

[0093] Manually control the position of the movable base plate to achieve a sound-absorbing back cavity depth of 12mm, with the upper half of the micro-slits of the fixed and movable micro-slit plates completely overlapping, as the initial state. Connect the movable base plate and the movable micro-slit plate via a slot using a rotating rod.

[0094] like Figure 3 The diagram shows the sound absorption coefficient curve after the rotor rotates 10 times in 360° increments from its initial state. Because the increment is 360°, the microchannel area formed by the fixed and moving micro-slit plates remains constant. With the rotation of the rotor, the movable base plate moves axially due to the threaded connection, increasing the sound-absorbing back cavity depth from 12mm to 60mm at a rate of 4.8mm / rad. By controlling the depth of the sound-absorbing back cavity, an adjustment range of approximately 600-1430Hz is achieved, and the resonant frequency can be shifted by 830Hz.

[0095] Example 5:

[0096] The multi-parameter simultaneous control method of the frequency-adjustable micro-slit plate sound-absorbing structure is as follows:

[0097] Manually control the position of the movable base plate to achieve a sound-absorbing back cavity depth of 12mm, with the upper half of the micro-slits of the fixed and movable micro-slit plates completely overlapping, as the initial state. Connect the movable base plate and the movable micro-slit plate via a slot using a rotating rod.

[0098] like Figure 4 The diagram shows the sound absorption coefficient curve after the rotor rotates 10 times in 375° increments from its initial state. Because the increment is 375°, each rotation causes the fixed and moving micro-slit plates to shift by 15°, similar to the variation in Example 3. Simultaneously, due to the axial movement of the movable base plate, the sound-absorbing back cavity depth increases from 12mm to 62mm at a rate of 5mm / rad, ultimately achieving dual adjustment of the slit ratio and back cavity depth. Adjustment between approximately 250-1430Hz is achieved through the control of dual structural parameters, and the resonant frequency can be shifted by 1180Hz.

Claims

1. A frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control, characterized in that: Includes fixed micro-slit plate (1), movable micro-slit plate (2), sound-absorbing back cavity, and rotary rod (5); The fixed micro-slit plate (1) is used to seal the open position at the upper end of the sound-absorbing back cavity; The moving micro-slit plate (2) is placed below the fixed micro-slit plate (1) and is located inside the sound-absorbing back cavity; The movable micro-slit plate (2) is connected to the swivel rod (5) through a slot; The sound-absorbing back cavity is an open cavity at the top, including the main cavity body (3) and a movable bottom plate (4). The main cavity (3) is a hollow cavity with openings at both ends; The movable base plate (4) is connected to the bottom end of the main cavity (3) and can move along the axial direction of the main cavity (3); The movable base plate (4) is connected to the rotating rod (5) through a slot; The rotating rod (5) is rotatable, and when it rotates, it drives the movable base plate (4) and the movable micro-slit plate (2) to rotate synchronously. While the rotating rod (5) drives the movable base plate (4) to rotate, the movable base plate (4) moves axially inside the main cavity (3) to adjust the depth of the sound-absorbing back cavity; When the rotating rod (5) drives the moving micro-slit plate (2) to rotate, it changes the cross-sectional area of ​​the microchannel between the fixed micro-slit plate (1) and the moving micro-slit plate (2), thereby adjusting the opening rate of the moving micro-slit plate (2); When the opening ratio of the moving micro-slit plate (2) decreases, the depth of the sound-absorbing back cavity increases; The fixed micro-slit plate (1) and the moving micro-slit plate (2) are provided with multiple annular micro-slits; The upper half of the fixed micro-slit plate (1) has a plurality of annular micro-slits evenly distributed, and the radius of these annular micro-slits shows an increasing trend. The upper and lower halves of the moving micro-slit plate (2) are evenly distributed with multiple annular micro-slits, and the radius of these annular micro-slits increases in an increasing trend. Among them, the angle between the two ends of the annular micro-slit in the upper half of the moving micro-slit plate (2) and the center is greater than the angle between the two ends of the annular micro-slit in the lower half and the center.

2. The frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control according to claim 1, characterized in that: The main cavity (3) has threads with the same parameters inside as the movable base plate (4) at its outer end.

3. The frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control according to claim 2, characterized in that: The direction of movement of the movable base plate (4) is determined by the direction of the thread rotation, and the speed of movement is determined by the thread pitch.

4. The frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control according to claim 1, characterized in that: The fixed micro-slit plate (1) and the moving micro-slit plate (2) are arranged coaxially in a micro-slit ring, and the overlapping part of the two micro-slits forms a micro-channel for sound waves to enter the sound-absorbing back cavity.

5. The frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control according to claim 1, characterized in that: When the moving micro-slit plate (2) rotates, the microchannel exists in the following three situations: Case 1: The micro-slits of the fixed micro-slit plate (1) only overlap with the micro-slits of the upper half of the moving micro-slit plate (2); Case 2: The micro-slits of the fixed micro-slit plate (1) only overlap with the micro-slits of the lower half of the moving micro-slit plate (2); Case 3: The micro-slits of the fixed micro-slit plate (1) overlap with the micro-slits of the upper and lower parts of the moving micro-slit plate (2); The slit width parameter of the microchannel differs depending on the three different conditions.

6. The frequency-adjustable micro-slit plate sound-absorbing structure with multi-parameter control according to claim 1, characterized in that: The opening rate changes with the rotation of the moving micro-slit plate (2) in a period of 360°.

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