Multi-mode low-medium frequency noise reduction silencer

Abstract

The utility model discloses a multi-mode low-medium frequency noise reduction silencer. Noise reduction of an exhaust system is achieved mainly through multi-stage cooperation of an expansion cavity, a Helmholtz cavity and an elastic damper. During working, most airflow enters the third cavity through the air inlet main pipe, and a small part of airflow enters the second cavity through the air inlet bypass pipe, so that the airflow of the air inlet main pipe enters an expansion cavity formed by the second cavity and the third cavity, and meanwhile, part of sound enters the first cavity through the air inlet bypass pipe; therefore, the first cavity forms a Helmholtz resonant cavity; secondly, after entering an expansion cavity composed of a second cavity and a third cavity, the airflow pushes away an elastic damper through the airflow and then enters a middle reducer pipe, after passing through the middle reducer pipe, part of the high-frequency airflow enters a fourth cavity through a third micropore structure of the middle reducer pipe, noise of the high-frequency airflow is absorbed through silencing cotton, and the noise of the high-frequency airflow is reduced; and part of the air flow enters the fifth chamber, enters the air outlet pipe through the fifth chamber, passes through the transition pipe through the air outlet pipe and finally flows out of the bag eliminating body.

Description

Multimodal low-mid frequency noise reduction silencer Technical Field

[0001] This utility model relates to the field of engine exhaust system technology, and in particular to a multimodal low-to-mid frequency noise reduction muffler. Background Technology

[0002] With the widespread use of internal combustion engines and other power machinery, exhaust system noise has become a significant threat to environmental pollution and human health. Low-frequency noise (typically referring to the 20-500Hz band) presents a challenge for noise control due to its long wavelength, strong penetration, and slow attenuation. Traditional exhaust silencing technologies mainly rely on sound-absorbing materials, perforated pipes, or simple expansion cavity structures, but these have significant limitations in the low-frequency range, specifically in the following aspects:

[0003] 1. Insufficient sound-absorbing material efficiency: Porous sound-absorbing materials (such as glass fiber and metal wool) consume sound energy through viscous friction, but their sound absorption coefficient decreases sharply with decreasing frequency, resulting in weak attenuation of low-frequency noise. In addition, harsh working conditions such as high temperature and oil contamination can easily lead to material aging and failure, which restricts their long-term stability in the exhaust system.

[0004] 2. Narrow bandwidth of a single expansion cavity: Traditional expansion cavities achieve noise reduction through acoustic impedance mismatch caused by abrupt changes in cross-sectional area. However, their effective noise reduction frequency band is strictly limited by the cavity geometry and is usually only for specific frequencies (such as the quarter-wavelength resonant frequency). To cover wide-band noise, multiple expansion cavities need to be connected in series, which leads to an increase in muffler size and airflow resistance (back pressure), affecting engine power output and fuel economy.

[0005] 3. Tuning limitations of Helmholtz resonators: Helmholtz resonators generate narrowband resonance absorption through a neck-cavity structure, which can precisely suppress specific low-frequency noise (such as engine fundamental frequency harmonics). However, its resonant frequency is fixed, making it difficult to adapt to changes in operating conditions (such as frequency shifts caused by speed fluctuations), and multi-band noise reduction requires multiple independent cavities, further increasing structural complexity and manufacturing costs.

[0006] 4. Conflict between airflow pulsation and back pressure: Passive valves (such as pressure regulating valves) can balance back pressure by dynamically adjusting the exhaust flow area, but their opening and closing actions easily induce airflow pulsation noise, especially in the low-frequency range where secondary noise sources may be generated. In existing designs, the coordination between valve control strategies and acoustic structures is insufficient, making it difficult to achieve both noise reduction performance and exhaust efficiency. Summary of the Invention

[0007] The purpose of this invention is to provide a multimodal low-mid frequency noise reduction muffler that solves the problem of low-mid frequency noise in the exhaust system through various types of chambers.

[0008] To solve the above-mentioned technical problems, this utility model provides a multimodal low-mid frequency noise reduction silencer, including a noise reduction body, a left end plate and a right end plate;

[0009] The internal cavity of the anti-packet body is provided with partitions 1, 2, 3 and 4, which divide the inner cavity of the anti-packet body from left to right into a first chamber, a second chamber, a third chamber, a fourth chamber and a fifth chamber.

[0010] The body containing the bag-eliminating device is provided with a T-shaped main air intake pipe and an air intake bypass pipe. The main air intake pipe passes through the bag-eliminating device in a vertical direction and extends into the third chamber. One end of the air intake bypass pipe is connected to the main air intake pipe, and the other end passes through the second partition and the first partition in sequence and extends into the first chamber.

[0011] The body of the packaging is provided with an intermediate reducing pipe, which is horizontally installed on the third partition and the fourth partition. One end of the intermediate reducing pipe is connected to the third chamber, and the other end is connected to the fifth chamber.

[0012] The body of the bag-discharging device is also provided with an air outlet pipe, which passes through the fourth partition, the third partition, the second partition, the first partition and the left end plate in sequence. One end of the air outlet pipe is connected to the fifth chamber, and the other end extends to the outside of the left end plate.

[0013] Preferably, the end of the intermediate reducing pipe located in the third chamber is provided with an elastic damping valve.

[0014] Preferably, the end of the main intake pipe located inside is sealed, and a first microporous structure is formed on the side wall to guide airflow into the third chamber.

[0015] Preferably, the partition has a notch, which allows the second chamber and the third chamber to be naturally connected to form an expansion cavity.

[0016] Preferably, the intake bypass pipe has a second microporous structure on the side wall inside the second chamber, through which airflow is guided into the second chamber.

[0017] Preferably, the intake bypass pipe extends horizontally into the first chamber and communicates with the first chamber, making the first chamber a Helmholtz resonant cavity.

[0018] Preferably, the intermediate reducing pipe has a third microporous structure on the side wall of the fourth chamber, through which airflow is guided into the fourth chamber, and the fourth chamber is provided with sound-absorbing cotton.

[0019] Preferably, the first partition, the second partition, the third partition, and the fourth partition are welded and fixed to the inner wall of the anti-packet body.

[0020] Preferably, the end of the main intake pipe is provided with an intake duct, which is tightly connected to the external exhaust pipe.

[0021] Preferably, the end of the exhaust pipe is provided with a transition pipe, which is connected to an external exhaust pipe.

[0022] Compared with the prior art, the beneficial effects of this utility model are:

[0023] This multimodal low-mid frequency noise reduction muffler aims to solve the low-mid frequency noise problem in exhaust systems. It primarily achieves noise reduction through a multi-stage synergy of an expansion chamber, a Helmholtz chamber, and an elastic damper. After entering the exhaust pipe, most of the airflow enters the third chamber through the main intake pipe, while a small portion enters the second chamber via the intake bypass pipe. This allows the airflow from the main intake pipe to enter the expansion chamber, which is composed of the second and third chambers. Simultaneously, some sound enters the first chamber through the intake bypass pipe, thus creating a Helmholtz resonant chamber in the first chamber. Next, the airflow enters the expansion chamber again, where it pushes aside the elastic damper and enters the intermediate reducer. After passing through the intermediate reducer, some high-frequency airflow enters the fourth chamber through the third microporous structure of the reducer. High-frequency noise is absorbed by the sound-absorbing cotton, while some airflow enters the fifth chamber, then the exhaust pipe, and finally flows out through the transition pipe and out of the muffler body. The advantages of this multimodal low-mid frequency noise reduction muffler are as follows:

[0024] 1. Frequency band expansion: After the high-temperature and high-pressure exhaust gas enters the expansion cavity, the flow cross-sectional area increases, the airflow velocity decreases, and some kinetic energy is converted into heat energy, reducing airflow pulsation noise. The expansion cavity can solve the problem of low and mid-frequency broadband noise.

[0025] 2. Complementary to the Helmholtz cavity: The expanded cavity is responsible for broadband low-to-mid frequency noise, while the Helmholtz cavity absorbs specific frequencies (such as engine fundamental frequency harmonics) through narrowband resonance. Together, they cover the entire low-to-mid frequency range.

[0026] 3. Back pressure adjustment: Combined with the elastic damper, the exhaust back pressure is dynamically adjusted to avoid engine power loss due to excessive expansion chamber cross-sectional area. The elastic damper can also suppress low-frequency noise during idling. Attached Figure Description

[0027] Figure 1 is a structural schematic diagram of the multimodal low-mid frequency noise reduction silencer provided by this utility model;

[0028] Figure 2 is a schematic diagram of the internal structure of the multimodal low-mid frequency noise reduction silencer provided by this utility model;

[0029] Figure 3 is a front view of the internal structure of the multimodal low-mid frequency noise reduction muffler provided by this utility model.

[0030] In the diagram: 1. Packing eliminator; 2. Left end plate; 3. Right end plate; 4. Partition 1; 5. Partition 2; 6. Partition 3; 7. Partition 4; 8. Main intake pipe; 9. Intake bypass pipe; 10. Intermediate reducer pipe; 11. Exhaust pipe; 12. Flexible damping valve; 13. Intake duct; 14. Transition pipe; 100. First chamber; 200. Second chamber; 300. Third chamber; 400. Fourth chamber; 500. Fifth chamber; 600. External exhaust pipe; 700. External exhaust pipe. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0032] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Examples

[0034] This utility model provides a multimodal low-mid frequency noise reduction silencer, as shown in Figures 1-3, including a silencer body 1, a left end plate 2, and a right end plate 3; the silencer body 1 is internally equipped with partitions 4, 5, 6, and 7, which divide the inner cavity of the silencer body 1 from left to right into a first chamber 100, a second chamber 200, a third chamber 300, a fourth chamber 400, and a fifth chamber 500; the silencer body 1 is provided with a T-shaped main intake pipe 8 and an intake bypass pipe 9. The main intake pipe 8 passes vertically through the silencer body 1 and extends into the third chamber 300, and one end of the intake bypass pipe 9 is connected to the main intake pipe 8. The other end passes through the second partition 5 and the first partition 4 in sequence and extends into the first chamber 100; the anti-packet body 1 is provided with an intermediate reducing pipe 10, which is horizontally installed on the third partition 6 and the fourth partition 7, and one end of the intermediate reducing pipe 10 is connected to the third chamber 300, and the other end is connected to the fifth chamber 500; the anti-packet body 1 is also provided with an air outlet pipe 11, which passes through the fourth partition 7, the third partition 6, the second partition 5, the first partition 4 and the left end plate 2 in sequence, and one end of the air outlet pipe 11 is connected to the fifth chamber 500, and the other end extends to the outside of the left end plate 2.

[0035] Specifically, the end of the intermediate variable diameter pipe 10 located in the third chamber 300 is provided with an elastic damping valve 12. The elastic damper 12 dynamically adjusts the exhaust back pressure to avoid engine power loss due to excessive expansion chamber cross-sectional area. The elastic damper can also suppress low-frequency noise during idling.

[0036] Specifically, the intake main pipe 8 is sealed at its inner end, and a first microporous structure is formed on its side wall to guide airflow into the third chamber 300. The partition plate 5 has a notch, allowing the second chamber 200 and the third chamber 300 to naturally connect, forming an expansion chamber. After the high-temperature and high-pressure exhaust gas enters the expansion chamber, the flow cross-sectional area increases, the airflow velocity decreases, and some kinetic energy is converted into heat energy, reducing airflow pulsation noise. The expansion chamber can solve the problem of low- and mid-frequency broadband noise.

[0037] Furthermore, the intake bypass pipe 9 has a second microporous structure on its side wall inside the second chamber 200, through which airflow is guided into the second chamber 200.

[0038] Specifically, the intake bypass pipe 9 extends horizontally into the first chamber 100 and communicates with the first chamber 100, making the first chamber 100 a Helmholtz resonant cavity. The expansion cavity is responsible for broadband low-to-mid-frequency noise, while the Helmholtz cavity absorbs specific frequencies, such as the engine's fundamental frequency harmonics, through narrow-band resonance. Together, they cover the entire low-to-mid frequency range.

[0039] Specifically, the intermediate reducing pipe 10 has a third microporous structure on its side wall inside the fourth chamber 400. Airflow is guided into the fourth chamber 400 through this third microporous structure, and the fourth chamber 400 is equipped with sound-absorbing cotton. The sound-absorbing cotton absorbs high-frequency airflow noise.

[0040] Specifically, the first partition 4, the second partition 5, the third partition 6, and the fourth partition 7 are welded and fixed to the inner wall of the anti-packet body 1.

[0041] Specifically, the intake main pipe 8 is provided with an intake base pipe 13 at its end, which is tightly connected to the external exhaust pipe 600.

[0042] Specifically, the end of the exhaust pipe 11 is provided with a transition pipe 14, which is connected to the external exhaust pipe 700.

[0043] Furthermore, an air intake reinforcement plate is provided inside the anti-packet body 1, which mainly supports the T-shaped main air intake pipe 8 and the air intake bypass pipe 9; multiple reinforcing ribs are also provided, which mainly support the internal component structure, improve the anti-packet body mode, and reduce the vibration, noise and abnormal sounds caused by the structure of the anti-packet body.

[0044] During operation, after the airflow passes through the intake duct 13, most of it enters the third chamber 300 through the main intake duct 8, while a small portion of the airflow enters the second chamber 200 through the intake bypass duct 9. This allows the airflow from the main intake duct 8 to enter the expansion chamber composed of the second chamber 200 and the third chamber 300. Simultaneously, some sound enters the first chamber 100 through the intake bypass duct 9, thus forming a Helmholtz resonant cavity in the first chamber 100. Next, the airflow enters the expansion chamber composed of the second chamber 200 and the third chamber 300, and then pushes aside the elastic damper 12 before entering the intermediate reducer duct 10. After passing through the intermediate reducer duct 10, some high-frequency airflow enters the fourth chamber 400 through the third microporous structure of the intermediate reducer duct 10. The high-frequency airflow noise is absorbed by the sound-absorbing cotton, and some airflow enters the fifth chamber 500. After entering the fifth chamber 500, it enters the exhaust pipe, then flows through the exhaust pipe 11 and the transition pipe 14, finally exiting the masking body.

[0045] The above description is only a description of the preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A multimodal low-to-mid frequency noise reduction silencer, characterized in that, The device includes a blister packing body (1), a left end plate (2), and a right end plate (3). The blister packing body (1) is internally divided into a first chamber (100), a second chamber (200), a third chamber (300), a fourth chamber (400), and a fifth chamber (500) by partitions 1 (4), 2 (5), 3 (6), and 4 (7) at intervals, dividing the inner cavity of the blister packing body (1) from left to right into a first chamber (100), a second chamber (200), a third chamber (300), a fourth chamber (400), and a fifth chamber (500). The blister packing body (1) contains a T-shaped main intake pipe (8) and an intake bypass pipe (9). The main intake pipe (8) passes vertically through the blister packing body (1) and extends into the third chamber (300). One end of the intake bypass pipe (9) is connected to the main intake pipe (8), and the other end passes sequentially through partitions 2 (4), 2 (5), 3 (6), 4 (7), and 5 (8). The partition 1 (4) extends into the first chamber (100); the anti-packet body (1) is provided with an intermediate variable diameter pipe (10), which is horizontally installed on the partition 3 (6) and the partition 4 (7), and one end of the intermediate variable diameter pipe (10) is connected to the third chamber (300), and the other end is connected to the fifth chamber (500); the anti-packet body (1) is also provided with an air outlet pipe (11), which passes through the partition 4 (7), the partition 3 (6), the partition 2 (5), the partition 1 (4) and the left end plate (2) in sequence, and one end of the air outlet pipe (11) is connected to the fifth chamber (500), and the other end extends to the outside of the left end plate (2).

2. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The intermediate reducing pipe (10) is provided with an elastic damping valve (12) at its end located in the third chamber (300).

3. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The intake main pipe (8) is sealed at the end inside, and a first micropore structure is opened on the side wall to guide the airflow into the third chamber (300).

4. The multimodal low-mid frequency noise reduction silencer as described in claim 3, characterized in that, The second partition (5) has a notch, which allows the second chamber (200) and the third chamber (300) to be naturally connected to form an expansion cavity.

5. The multimodal low-mid frequency noise reduction silencer as described in claim 4, characterized in that, The intake bypass pipe (9) has a second microporous structure on the side wall inside the second chamber (200) to guide airflow into the second chamber (200).

6. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The intake bypass pipe (9) extends horizontally into the first chamber (100) and communicates with the first chamber (100), so that the first chamber (100) becomes a Helmholtz resonant cavity.

7. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The intermediate reducing pipe (10) has a third microporous structure on its side wall inside the fourth chamber (400). The airflow is guided into the fourth chamber (400) through the third microporous structure, and the fourth chamber (400) is provided with sound-absorbing cotton.

8. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The first partition (4), the second partition (5), the third partition (6), and the fourth partition (7) are welded and fixed to the inner wall of the anti-packet body (1).

9. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The intake main pipe (8) is provided with an intake base pipe (13) at its end, which is tightly connected to the external exhaust pipe (600) through the intake base pipe (13).

10. The multimodal low-mid frequency noise reduction silencer as described in claim 1, characterized in that, The end of the exhaust pipe (11) is provided with a transition pipe (14), which is connected to the external exhaust pipe (700) through the transition pipe (14).

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