Switchable mode passive hearing protection earmuff

Abstract

The application belongs to the technical field of ear protection masks, and particularly relates to a passive protective ear mask with switchable modes, which comprises an inner shell, an outer shell, a shell connecting piece, a locking ring, a headband and a headband connecting piece, the headband is connected with the outer shell through the headband connecting piece, the inner shell is clamped with the shell connecting piece, the outer wall of the inner shell is uniformly distributed with a plurality of damping and sound absorption components, the outer shell is slidingly connected with the shell connecting piece, the outer shell is arranged in a spaced manner with the inner shell, and the locking ring is slidingly connected with the shell connecting piece; the protective ear mask solves the problem that the existing passive ear mask cannot dynamically adjust the optimal protection strategy in a strong noise environment, and through the introduction of a nonlinear stiffness design, the protective ear mask has a simple and reliable structure, and has excellent adaptability and comprehensive damping and sound absorption performance.

Description

Technical Field

[0001] This invention relates to the field of earmuff technology, and more specifically, to a passive protective earmuff with switchable modes. Background Technology

[0002] In modern industrial production, the main noise threat faced by workers is transient, high-intensity, and wide-spectrum impact noise (such as the operation of large equipment and mechanical impacts). Its destructive low-frequency energy (shock waves) can easily cause hearing damage or even temporary disability, while mid-to-high-frequency energy severely affects the clarity of voice communication. Existing protective earmuffs are divided into passive (passive) sound insulation / absorption types and active noise cancellation types. The former mainly relies on the physical structure and material properties of its earmuff shell, ear pads, and headband to achieve sound insulation, and has a good attenuation effect on mid-to-high-frequency noise, but its low-frequency impact vibration isolation efficiency is low, and it is relatively thick and heavy, resulting in poor wearing comfort. The latter is more effective against continuous mid-to-low-frequency noise, but it has a slow response and is prone to failure when facing transient strong impact noise, which may generate secondary noise. Furthermore, its electronic system has poor reliability and high power consumption in harsh environments.

[0003] Secondly, existing passive protective earmuffs have limited performance and poor adaptability, failing to dynamically adjust to complex and ever-changing noise characteristics, and unable to fundamentally change the physical vibration isolation and sound absorption characteristics of the earmuff structure. Furthermore, the internal space of the earmuff is extremely limited, making it difficult to simultaneously accommodate high-performance vibration damping mechanisms and wide-bandwidth, high-efficiency sound-absorbing structures.

[0004] Therefore, a switchable-mode passive protective earmuff is needed to solve the problem that existing passive protective earmuffs have limited protective performance and cannot dynamically adjust the optimal protection strategy. Summary of the Invention

[0005] The purpose of this invention is to provide a switchable passive protective earmuff with two protective modes: vibration reduction and sound absorption. The two modes can be switched without replacing any parts. Furthermore, a nonlinear stiffness design is introduced into the earmuff, which does not rely on external energy and achieves excellent protective function solely through its own physical structure and material properties. This solves the problem that existing passive protective earmuffs have limited protective performance and cannot dynamically adjust to the optimal protective strategy.

[0006] The technical solution of the present invention is as follows:

[0007] A switchable mode passive protective earmuff, comprising:

[0008] The device comprises an inner shell, an outer shell, a shell connector, a locking ring, a headband, and a headband connector. The headband is connected to the outer shell via the headband connector. The inner shell is snapped into the shell connector. The outer wall of the inner shell is evenly distributed with several vibration damping and sound absorbing components. The outer shell is slidably connected to the shell connector, and the outer shell and the inner shell are spaced apart. The locking ring is slidably connected to the shell connector.

[0009] The locking ring has a raised ring on the upper edge of its inner wall, a plurality of sliders on the lower edge of its inner wall, and the sliders are evenly spaced. The locking ring has a pressing block on its outer wall, and the pressing block is integrally formed with the raised ring.

[0010] Furthermore, the vibration damping and sound absorption component is connected between the inner wall of the outer shell and the outer wall of the inner shell; the vibration damping and sound absorption component includes a resonant unit and a damping diaphragm, the resonant unit and the damping diaphragm are integrally formed, the resonant unit has a sound absorption hole neck, a sound absorption cavity is formed between the damping diaphragm and the outer wall of the inner shell, and the sound absorption cavity is connected to the sound absorption hole neck.

[0011] Furthermore, the sound absorption coefficient of the vibration damping and sound absorbing component satisfies:

[0012]

[0013] In the formula:

[0014] l eff To reduce the effective length of the sound-absorbing hole neck, l n l is the length of the sound-absorbing hole neck. eff =l n +0.85d n ;

[0015] S is the cross-sectional area of ​​the vibration-damping and sound-absorbing hole neck.

[0016] d n V is the diameter of the sound-absorbing hole neck, and V is the volume of the sound-absorbing cavity;

[0017] Z0 is the air acoustic impedance, Z0=ρ0c0;

[0018] ρ0 is the air density, c0 is the speed of sound, and ω is the angular frequency of the sound wave;

[0019] R Z For effective acoustic damping, j is an imaginary term.

[0020] Furthermore, the dispersion equation of the vibration damping and sound absorbing component satisfies:

[0021]

[0022] In the formula:

[0023] R is the radius of the vibration damping and sound absorbing component, and ρ is the material density of the vibration damping and sound absorbing component;

[0024] h is the thickness of the outer shell, and D is the bending stiffness of the outer shell.

[0025] E is the Young's modulus of the vibration damping and sound absorbing component, and v is the Poisson's ratio of the vibration damping and sound absorbing component;

[0026] k is the equivalent stiffness of the vibration damping and sound absorbing component, and m is the equivalent mass of the vibration damping and sound absorbing component.

[0027] Furthermore, the outer wall of the outer shell is provided with a sound-absorbing hole that matches the sound-absorbing hole neck, the outer edge of the outer shell is provided with an outer shell groove, and the inner edge of the outer shell is provided with an outer shell retaining ring.

[0028] Furthermore, an inner shell retaining ring is provided along the inner edge of the inner shell, and sound-absorbing foam that is adapted to the structure of the inner shell is connected to the inner wall of the inner shell.

[0029] Furthermore, the housing connector includes a retainer, which is provided with a slide rail adapted to the slider and a housing buckle adapted to the housing retainer groove, and the housing buckle abuts against the protruding ring. The housing connector also has a housing groove adapted to the housing body, a housing limiting ring adapted to the housing retainer ring, an inner housing groove adapted to the inner housing, and an inner housing limiting ring adapted to the inner housing retainer ring.

[0030] Furthermore, the housing connector also includes an inner housing rubber ring and an outer housing rubber ring, wherein the outer housing rubber ring is located within the outer housing groove and the inner housing rubber ring is located within the inner housing groove.

[0031] Furthermore, the headband connector includes an outer sleeve and a telescopic inner sleeve, the outer sleeve and the telescopic inner sleeve are slidably connected, the telescopic inner sleeve is located at the end of the headband, and the outer sleeve is connected to the outer shell.

[0032] The beneficial effects of this invention are as follows:

[0033] The passive protective earmuffs of this invention have two protection modes: vibration reduction and sound absorption. When it is necessary to switch from the vibration reduction-dominant mode to the sound absorption-dominant mode, pressing the pressing block will complete the switch. When it is necessary to switch from the sound absorption-dominant mode to the vibration reduction-dominant mode, simply pulling the locking ring will complete the switch. The switching between the vibration reduction-dominant mode and the sound absorption-dominant mode of the protective earmuffs can be achieved without replacing any parts. Furthermore, by introducing a nonlinear stiffness design, this invention makes the protective earmuff structure simple and reliable. It does not rely on any external energy source and can achieve excellent protective function solely through the physical structure and material properties of the earmuffs themselves.

[0034] In the vibration damping-dominant mode, the equivalent stiffness of the vibration damping and sound-absorbing component of the passive protective earmuff of the present invention approaches zero, which can maximize the isolation and dissipation of low-frequency impact energy of transient strong noise and significantly suppress the structural vibration transmitted by the shock wave; in the sound absorption-dominant mode, the outer shell of the passive protective earmuff of the present invention is displaced, the sound absorption cavity is expanded, and the sound absorption hole neck is elongated, so that the earmuff has a good sound absorption effect on low-frequency noise.

[0035] The passive protective earmuffs of the present invention solve the problem that existing passive protective earmuffs cannot dynamically adjust the optimal protection strategy in high noise environments. Furthermore, the passive protective earmuffs of the present invention have better reliability, adaptability, and excellent comprehensive vibration reduction and sound absorption performance. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the overall structure of the earmuff of the present invention;

[0038] Figure 2 This is a schematic diagram of the exploded structure of the earmuff of the present invention;

[0039] Figure 3 This is a cross-sectional view of the earmuff of the present invention in the vibration damping dominant mode;

[0040] Figure 4 for Figure 3 A magnified view of a section at point A in the middle;

[0041] Figure 5 This is a cross-sectional view of the earmuff of the present invention in the sound absorption-dominant mode;

[0042] Figure 6 for Figure 5 A magnified view of a section at point B in the middle;

[0043] Figure 7 This is a three-dimensional structural diagram of the housing connector and unlocking ring of the present invention;

[0044] Figure 8 This is a schematic diagram of the simulation results of the vibration reduction performance of the earmuffs of the present invention;

[0045] Figure 9 This is a schematic diagram of the simulation results of the sound absorption performance of the earmuffs of the present invention.

[0046] Legend: 1-Outer shell; 11-Sound receiving hole; 12-Outer shell slot; 13-Outer shell retaining ring; 2-Shell connecting piece; 21-Slot; 211-Slide rail; 212-Outer shell buckle; 213-Outer shell limiting ring; 214-Inner shell limiting ring; 22-Inner shell rubber ring; 23-Outer shell rubber ring; 3-Locking ring; 31-Pressing block; 32-Slider; 33-Protruding ring; 4-Headband; 5-Headband connecting piece; 6-Flexible foam; 7-Vibration damping and sound absorbing component; 71-Sound absorbing hole neck; 72-Resonant unit; 73-Vibration damping diaphragm; 74-Sound absorbing cavity; 8-Inner shell; 81-Inner shell retaining ring; 9-Sound absorbing foam. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0049] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0050] Example 1

[0051] A switchable mode passive protective earmuff, comprising:

[0052] The inner shell 8, outer shell 1, shell connector 2, locking ring 3, headband and headband connector 5, the headband is connected to the outer shell 1 through the headband connector 5, the inner shell 8 is snapped into the shell connector 2, the outer wall of the inner shell 8 is evenly distributed with a number of vibration damping and sound absorbing components 7, the outer shell 1 is slidably connected to the shell connector 2, and the outer shell 1 and the inner shell 8 are spaced apart, the locking ring 3 is slidably connected to the shell connector 2;

[0053] The upper edge of the inner wall of the locking ring 3 is provided with a protruding ring 33, the lower edge of the inner wall of the locking ring 3 is provided with a number of sliders 32, and the sliders 32 are evenly spaced. The outer wall of the locking ring 3 is provided with a pressing block 31, and the pressing block 31 and the protruding ring 33 are integrally formed.

[0054] Furthermore, the vibration damping and sound absorbing component 7 is connected between the inner wall of the outer shell and the outer wall of the inner shell; the vibration damping and sound absorbing component 7 includes a resonant unit 72 and a damping diaphragm 73, the resonant unit 72 and the damping diaphragm 73 are integrally formed, the resonant unit 72 has a sound-absorbing hole neck 71, and a sound-absorbing cavity 74 is formed between the damping diaphragm 73 and the outer wall of the inner shell 8, and the sound-absorbing cavity 74 is connected to the sound-absorbing hole neck 71.

[0055] It should be noted that, in this embodiment, the sound-absorbing neck 71 has a certain wall thickness, and the resonant unit 72 is connected to the inner wall of the outer shell 1 through the sound-absorbing neck 71, so that a certain distance is maintained between the resonant unit 72 and the outer shell 1; the setting of this distance is mainly based on the following considerations:

[0056] First, this spacing allows for an extension of the actual effective length of the sound-absorbing hole neck 71; specifically, this spacing, together with the thickness of the resonant unit 72 itself, determines the length l of the sound-absorbing hole neck 71. n That is, l n This is equal to the sum of the thickness of the resonant unit 72 and the aforementioned spacing. By adjusting this spacing, the length l of the sound-absorbing hole neck 71 can be flexibly adjusted. n This optimizes the sound absorption performance.

[0057] Secondly, this spacing provides the necessary vibration space for the resonant unit 72; if the resonant unit 72 is in close contact with the inner wall of the outer casing 1, it will greatly limit the vibration amplitude of the resonant unit 72, thereby affecting its resonance effect and sound absorption performance. Maintaining a certain spacing can ensure that the resonant unit 72 can vibrate fully during operation, thus effectively exerting its sound absorption effect.

[0058] Furthermore, the sound absorption coefficient of the vibration damping and sound absorbing component 7 satisfies:

[0059]

[0060] In the formula:

[0061] l eff To reduce the effective length of the sound-absorbing hole neck (71), l n For the length of the sound-absorbing hole neck (71), l eff =l n +0.85d n ;

[0062] S is the cross-sectional area of ​​the vibration-damping and sound-absorbing hole neck 71.

[0063] d n V is the diameter of the sound-absorbing hole neck 71, and V is the volume of the sound-absorbing cavity 74;

[0064] Z0 is the air acoustic impedance Z0 = ρ0c0;

[0065] ρ0 is the air density, c0 is the speed of sound, and ω is the angular frequency of the sound wave;

[0066] R Z For effective acoustic damping, it is related to the actual structure and materials, and j is an imaginary term.

[0067] It is worth noting that, for reference Figure 8 When protection against lower frequency noise is required, the length of the sound-absorbing hole neck 71 can be increased. n At this time, the sound absorption frequency of the vibration damping and sound absorbing component 7 shifts to the left, and the sound absorption frequency of the vibration damping and sound absorbing component 7 decreases.

[0068] When it is necessary to enhance the sound absorption performance of protective earmuffs at specific frequencies, the diameter d of the sound absorption hole neck 71 can be appropriately increased. n ,refer to Figure 9 The sound absorption peak of the vibration damping and sound absorbing component 7 becomes wider, indicating that the sound absorption performance of the protective earmuff at this sound absorption frequency is enhanced, and the ratio of noise energy storage capacity to dissipation capacity in the vibration damping and sound absorbing component 7 increases.

[0069] When protection against higher frequency noise is required, the volume V of the sound-absorbing cavity 74 can be increased, which raises the structure's sound absorption frequency. The sound absorption coefficient A(ω) reaches its maximum value when the denominator is at its minimum, at which point the vibration-damping sound-absorbing component 7 exhibits the best sound absorption capability. Correspondingly:

[0070] angular frequency peak Linear frequency is

[0071] Furthermore, the dispersion equation of the vibration damping and sound absorbing component 7 satisfies:

[0072]

[0073] In the formula:

[0074] R is the radius of the vibration damping and sound absorbing component 7, and ρ is the material density of the vibration damping and sound absorbing component 7;

[0075] h is the thickness of the outer shell 1, and D is the bending stiffness of the outer shell 1.

[0076] E is the Young's modulus of the vibration damping and sound absorbing component 7, and v is the Poisson's ratio of the vibration damping and sound absorbing component 7;

[0077] k is the equivalent stiffness of the vibration damping and sound absorbing component 7, and m is the equivalent mass of the vibration damping and sound absorbing component 7.

[0078] When the angular frequency ω and wave number (α,β) satisfy the dispersion equation, a band gap will be formed during the process of vibration being transmitted from the outer shell 1 to the inner shell 8. The range of the band gap corresponds to the vibration isolation frequency range of the vibration damping and sound absorbing component 7. The thickness of the damping diaphragm 73 will directly affect the equivalent stiffness k of the vibration damping and sound absorbing component 7, and at the same time reflect the elastic deformation capability of the vibration damping and sound absorbing component 7.

[0079] It is worth noting that the band gap refers to the phenomenon that elastic waves (such as sound waves and vibration waves) within a specific frequency range cannot propagate in a material. In this embodiment, the vibration damping and sound absorbing components 7 are evenly arranged on the outer wall of the inner shell 8. When elastic waves encounter this periodic structure (a periodic structure refers to units with similar properties that are arranged infinitely in space according to a predetermined pattern), Bragg scattering and interference effects will occur, causing waves of certain frequencies to be completely reflected or significantly attenuated, forming a frequency range that is "prohibited from propagation".

[0080] The vibration damping and sound absorbing component 7 has a vibration isolation center frequency derived from the resonant frequency. Directly, reducing the thickness of the damping diaphragm 73 will shift the vibration isolation center frequency to lower frequencies. The equivalent mass m of the damping and sound-absorbing component 7 is determined by the coupling of the resonant unit 72, the damping diaphragm 73, the inner wall of the outer shell 1, and the outer wall of the inner shell 8. Increasing the equivalent mass m of the damping and sound-absorbing component 7 will also shift the vibration isolation center frequency to lower frequencies; the vibration isolation frequency width of the damping and sound-absorbing component 7... The coupling strength is controlled by the equivalent stiffness k and the equivalent mass m. Increasing the coupling between the vibration damping and sound absorbing component 7 and the outer shell 1 will increase the equivalent stiffness k, thereby increasing the vibration isolation frequency width Δω. With the equivalent stiffness k unchanged, increasing the equivalent mass m will narrow the vibration isolation frequency width Δω.

[0081] The equivalent stiffness k of the vibration damping and sound absorbing component 7 dominates the bandgap position and width, while the equivalent mass m is mainly used to compensate for frequency shift.

[0082] Furthermore, the outer wall of the outer shell 1 is provided with a sound-absorbing hole 11 that is adapted to the sound-absorbing hole neck 71, the outer edge of the outer shell 1 is provided with an outer shell groove 12, and the inner edge of the outer shell 1 is provided with an outer shell retaining ring 13.

[0083] Furthermore, an inner shell retaining ring 81 is provided on the inner edge of the inner shell 8, and a sound-absorbing foam 9 adapted to its structure is connected to the inner wall of the inner shell 8.

[0084] It should be noted that the protective earmuffs of this invention have both vibration reduction and sound absorption modes, see reference. Figure 5 and Figure 6When it is necessary to switch from vibration damping-dominant mode to sound absorption-dominant mode, press the pressing block 31. The pressing block 31 transmits pressure to the convex ring 33. Due to the guiding surface of the convex ring 33, the outer shell buckle 212 is subjected to outward force and undergoes elastic deformation, thereby separating from the outer shell slot 12, thus realizing the switch from vibration damping-dominant mode to sound absorption-dominant mode.

[0085] The pressing surface of the pressing block 31 is set to be concave for easy pressing;

[0086] refer to Figure 3 and Figure 4 When it is necessary to switch from the sound absorption-dominant mode to the vibration reduction-dominant mode, simply pull the locking ring 3 to re-engage the outer casing buckle 212 into the outer casing slot 12.

[0087] The vibration damping and sound absorption component 7 is a nonlinear stiffness structure, which can achieve nonlinear characteristics of high static and low dynamic stiffness. Under the premise of ensuring low cost, simple structure and high stability, it can simultaneously meet the requirements of effective low-frequency vibration damping and sound absorption of the earmuff. It makes up for the shortcomings of traditional linear vibration isolation earmuffs, which have "extremely limited internal space, making it difficult to accommodate high-performance vibration damping mechanism and wide-band high-efficiency sound absorption structure at the same time". It can meet the low-frequency vibration damping requirements with a smaller vibration damping structure size.

[0088] In the vibration reduction-dominated mode, refer to Figure 3 and Figure 4 The equivalent stiffness of the vibration damping and sound absorbing component 7 approaches zero, which is also known as the quasi-zero stiffness state (the quasi-zero stiffness state refers to the state where the system stiffness is close to zero near the equilibrium position. In this state, the system can significantly reduce its natural frequency, thereby providing effective vibration isolation in a lower frequency range). The vibration damping and sound absorbing component 7 is located between the inner shell 8 and the outer shell 1. In the quasi-zero stiffness state, the vibration damping and sound absorbing component 7 is compressed by the outer shell 1, resulting in a significant reduction in its equivalent stiffness k compared to the uncompressed state, which is the center frequency ω of the vibration isolation frequency band. r Significantly reduced. Although the bandwidth Δω of the vibration isolation frequency band is also reduced, the protective earmuffs based on quasi-zero stiffness still have good low-frequency vibration isolation performance;

[0089] In the sound absorption-dominant mode, reference Figure 5 and Figure 6 The outer casing latch 212 is unlocked from the outer casing groove. Compared to the vibration damping-dominant mode, the distance between the outer casing 1 and the inner casing 8 increases, the equivalent stiffness k of the vibration damping and sound-absorbing component 7 increases, and the low-frequency vibration isolation performance decreases. In the sound absorption-dominant mode, the volume V of the sound absorption cavity 74 of the vibration damping and sound-absorbing component 7 is larger than that in the vibration damping-dominant mode, the sound absorption peak of the vibration damping and sound-absorbing component 7 shifts to the left, and the sound absorption frequency... Reduce, while the effective length of the sound-absorbing hole neck 71 is l effAs the distance between the outer shell 1 and the inner shell 8 increases, the sound-absorbing hole neck 71 deforms and elongates slightly, further reducing the sound absorption frequency f. At this time, the vibration-damping sound-absorbing component 7 has better sound absorption performance compared to the vibration-damping dominant mode.

[0090] For example, in the vibration damping-dominant mode of the earmuff, assuming the material parameter density ρ = 1000 kg / m³ 3 Elastic modulus E = 1.7 GPa, Poisson's ratio ν = 0.4, radius R = 20 mm, bending stiffness Assume the equivalent mass m = 0.03 kg, the equivalent stiffness k = 54675 N / m, and the thickness of the outer shell 1 h = 1 mm.

[0091] At this time, the vibration isolation center frequency is:

[0092]

[0093] Vibration isolation frequency range:

[0094]

[0095] In the earmuff's sound absorption-dominant mode, assuming the length of the sound absorption hole neck 71 is l n It is 4mm in diameter and d in diameter. n If it is 3.5mm, then the effective length l eff =4 + 0.85 × 3.6 = 7.06 mm, assuming the volume V of the sound-absorbing cavity 74 is 1.59 × 10 -6 m 3 The air acoustic impedance Z0 = ρ0c0 = 1.21 × 343 ≈ 415 Pa·s / m

[0096] Resonance frequency

[0097] sound absorption coefficient

[0098] This indicates that the earmuffs of the present invention have excellent vibration reduction and sound absorption performance.

[0099] Furthermore, the housing connector 2 includes a retainer 21, which is provided with a slide rail 211 adapted to the slider 32 and a housing buckle 212 adapted to the housing slot 12. The housing buckle 212 abuts against the protruding ring 33. The housing connector 2 also has a housing groove adapted to the housing body 1, a housing limiting ring 213 adapted to the housing retaining ring 13, an inner housing groove adapted to the inner housing 8, and an inner housing limiting ring 214 adapted to the inner housing retaining ring 81.

[0100] Furthermore, the housing connector 2 also includes an inner housing rubber ring 22 and an outer housing rubber ring 23, with the outer housing rubber ring 23 located in the outer housing groove and the inner housing rubber ring 22 located in the inner housing groove.

[0101] The shell connector 2 is also connected to flexible foam 6 to improve wearing comfort.

[0102] The outer shell rubber ring 23 is nested within the outer shell groove. When the outer shell 1 is inserted into the outer shell groove, the outer shell rubber ring 23 is compressed. The outer shell rubber ring 23 has a certain elasticity, similar to a spring, and can provide axial thrust when the earcup's function mode is switched. At this time, the outer shell buckle 212 on the shell connector 2 and the protruding ring 33 on the locking ring 3 begin to move under the thrust of the outer shell rubber ring 23, thus switching to the earcup's sound absorption-dominant mode.

[0103] Furthermore, the headband connector 5 includes an outer sleeve and a telescopic inner sleeve, which are slidably connected. The telescopic inner sleeve is located at the end of the headband, and the outer sleeve is connected to the outer shell 1. The inner sleeve can slide freely inside the outer sleeve to adapt to the wearer's head and improve wearing comfort. The telescopic sleeve is prior art and will not be further described here.

[0104] Example 2

[0105] Based on Example 1, to further improve the sound absorption and vibration damping performance of the earmuffs of the present invention, this embodiment fills the space formed by the inner shell 8, the outer shell 1, and the vibration damping and sound absorption component 7 with porous foam. The principle is as follows:

[0106] The interconnected pores within porous foam form complex channels, allowing sound waves to be converted into heat energy through air friction and viscous resistance. Foam with specific pore sizes can resonate with sound waves of specific frequencies, enhancing energy dissipation. For example, microporous structures (pore sizes of 0.1–0.5 mm) are particularly effective for mid-frequency vocals (500 Hz–2 kHz). Furthermore, the elasticity of porous foam provides cushioning properties. When vibrations are transmitted to the earcup shell, the foam absorbs mechanical energy through deformation, thereby suppressing structural sound transmission.

[0107] Example 3

[0108] Based on Embodiment 1, in order to better improve the vibration reduction performance of the earmuff of the present invention, this embodiment increases the length of the sound-absorbing hole neck 71, extending it into the sound-absorbing cavity 74, thereby reducing the peak sound absorption frequency of the sound-absorbing component 7. Due to the effective length l of the sound-absorbing hole neck 71 eff =l n +0.85d n In the middle, the length of the sound-absorbing hole neck 71 is l n The addition of this element can significantly reduce the resonant absorption frequency without increasing the volume V of the sound-absorbing cavity.

[0109] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed above through embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A switchable-mode passive protective earmuff, characterized in that, include: The inner shell (8), outer shell (1), shell connector (2), locking ring (3), headband and headband connector (5), the headband is connected to the outer shell (1) through the headband connector (5), the inner shell (8) is snapped into the shell connector (2), and the outer wall of the inner shell (8) is evenly distributed with a number of vibration damping and sound absorbing components (7), the outer shell (1) is slidably connected to the shell connector (2), and the outer shell (1) and the inner shell (8) are spaced apart, the locking ring (3) is slidably connected to the shell connector (2); The upper edge of the inner wall of the locking ring (3) is provided with a convex ring (33), the lower edge of the inner wall of the locking ring (3) is provided with a plurality of sliders (32), and the sliders (32) are evenly spaced. The outer wall of the locking ring (3) is provided with a pressing block (31), and the pressing block (31) and the convex ring (33) are integrally formed. The vibration damping and sound absorption component (7) is connected between the inner wall of the outer shell and the outer wall of the inner shell; the vibration damping and sound absorption component (7) includes a resonant unit (72) and a damping diaphragm (73), the resonant unit (72) and the damping diaphragm (73) are integrally formed, the resonant unit (72) has a sound absorption hole neck (71), a sound absorption cavity (74) is formed between the damping diaphragm (73) and the outer wall of the inner shell (8), and the sound absorption cavity (74) is connected to the sound absorption hole neck (71); The sound absorption coefficient of the vibration damping and sound absorbing component (7) satisfies: In the formula: To reduce the effective length of the sound-absorbing hole neck (71), The length of the sound-absorbing hole neck (71) is... ; S is the cross-sectional area of ​​the vibration-damping and sound-absorbing hole neck (71). ; The diameter of the sound-absorbing pore neck (71) is... The volume of the sound-absorbing cavity (74); Z0 is the air acoustic impedance. ; air density, For the speed of sound, The angular frequency of the sound wave; For effective sound damping, For imaginary terms; The dispersion equation of the vibration damping and sound absorbing component (7) satisfies: In the formula: The radius of the vibration damping and sound absorbing component (7) is... The material density of the vibration damping and sound absorbing component (7); Let D be the thickness of the outer shell (1) and D be the bending stiffness of the outer shell (1). ; The Young's modulus of the vibration damping and sound absorbing component (7) is given. The Poisson's ratio for the vibration damping and sound absorbing component (7); For the equivalent stiffness of the vibration damping and sound absorbing component (7), The equivalent mass of the vibration damping and sound absorbing component (7); α and β are the wave number components of the vibration wave in two orthogonal directions within its propagation plane.

2. The earmuff according to claim 1, characterized in that, The outer wall of the outer shell (1) is provided with a sound-absorbing hole (11) that is adapted to the sound-absorbing hole neck (71), the outer edge of the outer shell (1) is provided with an outer shell groove (12), and the inner edge of the outer shell (1) is provided with an outer shell retaining ring (13). The inner edge of the inner shell (8) is provided with an inner shell retaining ring (81), and the inner wall of the inner shell (8) is connected with sound-absorbing foam (9) that is compatible with its structure.

3. The earmuff according to claim 2, characterized in that, The housing connector (2) includes a retainer (21), which is provided with a slide rail (211) adapted to the slider (32) and a housing buckle (212) adapted to the housing slot (12). The housing buckle (212) abuts against the protruding ring (33). The housing connector (2) is also provided with a housing groove adapted to the housing body (1), a housing limiting ring (213) adapted to the housing retaining ring (13), an inner shell groove adapted to the inner housing (8), and an inner shell limiting ring (214) adapted to the inner shell retaining ring (81).

4. The earmuff according to claim 3, characterized in that, The housing connector (2) also includes an inner shell rubber ring (22) and an outer shell rubber ring (23), the outer shell rubber ring (23) being located in the outer shell groove and the inner shell rubber ring (22) being located in the inner shell groove.

5. The earmuff according to claim 1, characterized in that, The headband connector (5) includes an outer sleeve and a telescopic inner sleeve, the outer sleeve and the telescopic inner sleeve are slidably connected, the telescopic inner sleeve is located at the end of the headband, and the outer sleeve is connected to the outer shell (1).

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