Double-layer metal corrugated pipe with sound absorption function

Abstract

The double-layer metal corrugated pipe with the sound absorption function comprises a two-layer corrugated pipe, a cavity dividing ring and a supporting ring, the two ends of the two-layer corrugated pipe are connected through the supporting ring, the cavity dividing ring is connected with the middle portion of the two-layer corrugated pipe, so that the space between the two-layer corrugated pipe is divided into several cavities, and airflow flows to the other end from one end of an inner pipe of the corrugated pipe; on the premise that the damping effect of the corrugated pipe is guaranteed, noise generated when airflow passes through an exhaust system is reduced, the sound absorption frequency domain range is enlarged through the design of the variable cavities and the open holes, friction between the two layers of corrugated pipes is reduced while normal work of the metal corrugated pipe is guaranteed through the arrangement of the step rigidity of the cavity dividing rings, and the service life of the metal corrugated pipe is prolonged. And the service life of the double-layer corrugated pipe structure is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of automobile NVH technology, in particular to a double-layer metal bellows with a sound absorption function. Background Art

[0002] With the rapid development of society and the economy, automobiles have become an indispensable means of transportation for people. Against the backdrop of rapid advancements in my country's automobile manufacturing technology, the power, ride comfort, and roadworthiness of existing fuel-powered vehicles have significantly improved. At the same time, people's demands for ride comfort and vehicle reliability are also increasing, becoming important indicators in evaluating a car's performance. Vehicle vibration, caused by the crankshaft rotation and fore-and-aft swaying of transversely mounted engines, is an unavoidable topic in evaluating vehicle comfort and reliability. Vehicle vibration and exhaust noise directly impact both ride comfort and reliability, leading to the increasing use of components designed to enhance comfort and reliability in automotive products.

[0003] Metal bellows are flexible metal connecting pipes made up of multiple transverse corrugations. They are widely used in automobile exhaust systems because of their light weight, good sealing, and ability to compensate for axial and radial displacements caused by changes in external forces.

[0004] Currently, the noise reduction capabilities of automotive metal bellows on the market primarily focus on reducing structure-borne noise, but there's no effective solution for airflow noise. When high-speed airflow in the exhaust system passes through the bellows, the irregular surface of the corrugated structure creates turbulence. This turbulence not only increases exhaust resistance but also causes airflow noise, which is particularly noticeable during high-speed driving or rapid acceleration.

[0005] In addition, during the installation and use of the metal bellows, the vibration of the bellows driven by the engine may cause friction between the bellows and adjacent components. Long-term friction will cause wear on the bellows surface and even perforation or rupture, reducing the life of the metal bellows. Summary of the Invention

[0006] In order to solve the technical problems of airflow noise and low service life of automotive metal bellows, the present invention provides a double-layer bellows structure, which can reduce the noise when the airflow passes through the pipe while ensuring the shock absorption performance of the bellows is met, and extend the service life of the metal bellows.

[0007] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0008] The technical solution adopted by the present invention is: a double-layer metal bellows with sound absorption function, comprising an outer bellows and an inner bellows, characterized in that the outer bellows is sleeved on the outside of the inner bellows

[0009] Preferably, the outer layer bellows and the inner layer bellows are both made of metal.

[0010] Preferably, the outer layer corrugated tube and the inner layer corrugated tube have different inner diameters, thicknesses and corrugation types.

[0011] Preferably, a cavity dividing ring is provided between the outer layer bellows and the inner layer bellows near the center, and the cavity dividing rings are provided in multiple groups.

[0012] Preferably: the cavity ring is composed of a low-rigidity outer ring and a high-rigidity inner ring, the top of the low-rigidity outer ring is attached to the inner side of the outer bellows, and the inner layer of the high-rigidity inner ring is attached to the outer side of the inner bellows.

[0013] Preferably, support rings are provided between the outer layer corrugated tube and the inner layer corrugated tube, near both ends.

[0014] Preferably, the surface of the inner corrugated tube is provided with a plurality of groups of small holes, and the sizes of the small holes can be varied.

[0015] Preferably, a guide plate is provided inside the inner corrugated tube, and the guide plate extends in the direction of airflow.

[0016] The present invention has a double-layer metal bellows structure, which can reduce the noise generated by airflow passing through the exhaust system while ensuring the shock-absorbing effect of the bellows itself. In the vibration process, the modal frequency and vibration form of the inner bellows and the outer bellows are different, so that the cavity volume between the two layers of bellows changes, so that the sound absorption frequency of the invention is expanded, and the airflow noise in a wider frequency band can be weakened; and the setting of the cavity dividing ring ensures the normal operation of the metal bellows while reducing the friction between the two layers of bellows, so that the service life of the double-layer bellows structure is improved.

[0017] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described below are only some embodiments. A person skilled in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

[0019] Figure 1 This is a partial cross-sectional view of a double-layer metal bellows with sound absorption function according to an embodiment of the present invention;

[0020] Figure 2This is a partial cross-sectional view of the inner layer bellows of a double-layer metal bellows with sound absorption function according to an embodiment of the present invention;

[0021] Figure 3 This is a cross-sectional view of a cavity ring of a double-layer metal bellows with a sound-absorbing function according to an embodiment of the present invention;

[0022] In the figure, 1. Outer bellows; 2. Support ring; 3. Inner bellows; 4. Small hole; 5. Dividing cavity ring; 6. Guide plate; 7. Low-rigidity outer ring; 8. High-rigidity inner ring.

[0023] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0025] Reference Figure 1 As shown, the outer bellows 1 of this embodiment is sleeved on the outside of the inner bellows 3. The outer bellows 1 and the inner bellows 3 of this embodiment are both made of metal. The outer bellows 1 and the inner bellows 3 of this embodiment have different inner diameters, thicknesses, and corrugation types. Among them, the outer bellows 1 and the inner bellows 3 will not resonate with each other due to the different modal frequencies and vibration forms. The metal material makes it have the same flexibility as a hose, while also having high temperature resistance, low temperature resistance, aging resistance, and corrosion resistance, and has a longer service life.

[0026] like Figure 1 As shown, a cavity dividing ring 5 is arranged near the center position between the outer layer bellows 1 and the inner layer bellows 3 of this embodiment, and multiple groups of cavity dividing rings 5 are provided; among them, because the two ends of the cavity dividing ring 5 are connected to the two layers of bellows, the stiffness of the outer layer bellows 1 and the stiffness of the inner layer bellows 3 are correlated, thereby increasing the overall stiffness, suppressing the mutual interference friction between the two layers of metal bellows, and improving the service life of the double-layer metal bellows.

[0027] like Figure 3As shown, the cavity ring 5 of this embodiment is composed of a low-rigidity outer ring 7 and a high-rigidity inner ring 8. The top of the low-rigidity outer ring 7 is attached to the inner side of the outer bellows 1, and the inner layer of the high-rigidity inner ring 8 is attached to the outer side of the inner bellows 1; wherein, the cavity ring 5 is composed of a low-rigidity outer ring 7 and a high-rigidity inner ring 8. When the double-layer bellows vibrates, the low-rigidity outer ring 7 is deformed first, and its amplitude is suppressed without affecting the normal deformation of the outer bellows 1. When the deformation is large enough, the deformation of the low-rigidity outer ring 7 ends, and the outer bellows 1 and the inner bellows 3 are mainly connected through the high-rigidity inner ring 8, which suppresses direct contact between the inner and outer tubes and reduces friction between the inner and outer tubes, thereby improving the service life of the double-layer metal bellows.

[0028] like Figure 1 As shown, in this embodiment, a support ring 2 is arranged between the outer bellows 1 and the inner bellows 3 near both ends. The support ring 2 is located at both ends of the outer bellows 1 and the inner bellows 3, and is used to support and isolate the two bellows, further reduce the resonance between the outer bellows 1 and the inner bellows 3, and at the same time cooperate with the cavity dividing ring 5 to form multiple groups of cavity chambers.

[0029] like Figure 1 、 2 As shown, the surface of the inner layer bellows 3 of the present embodiment is provided with multiple groups of small holes 4; the air flow flows from the left section to the right end of the inner layer bellows 3. When flowing inside, the air flow flows into its own cavity through the inner layer bellows 3, and then enters the cavity formed by the outer layer bellows 1, the support ring 2, the inner layer bellows 3 and the cavity dividing ring 5 through the small holes 4 on the inner layer bellows 3. The cavity silencer is performed twice on the air flow, so that the noise of the air flow is reduced. Moreover, since the metal wall of the inner layer bellows 3 in the area around the small holes 4 becomes thinner, it can change according to the flow rate of the air flow. When the air flow rate is large, it is convenient for the metal to be flanged in the direction of the air flow, and the aperture of the small hole 4 will increase. When the flow rate is small, the flange rebounds and the aperture decreases, so that the size of the small hole 4 has a certain plasticity to adapt to the sound absorption requirements of different flow rates.

[0030] like Figure 2 As shown, a guide plate 6 is provided on the inner side of the upper inner layer bellows 3 of the present embodiment, and the guide plate 6 extends in the direction of the airflow; wherein, when the airflow flows in the inner layer bellows 3, due to the presence of the guide plate 6, the gas flowing through the tube can flow smoothly in the inner layer bellows 3 without generating turbulence, which not only retains the plasticity of the bellows, but also forms a cavity with the guide plate 6 and the inner layer bellows 3, which also has a certain attenuation effect on noise. After the airflow flows into the cavity in the guide plate 6, the noise is again absorbed by the cavity through the small hole 4.

[0031] In addition, the micro-perforated sound-absorbing structure of the prior art is composed of a tiny perforated plate and a cavity behind it. When sound waves are incident on the micro-perforated plate, the sound waves enter the cavity through the small holes and generate vibrations in the cavity. Due to the viscous friction and heat conduction effect of the air in the small holes, the sound energy is converted into heat energy, thereby achieving sound absorption. In the present invention, the small holes 4 on the inner layer bellows 3 are micro-perforations, and the middle part of the double-layer bellows is divided into multiple cavities by the cavity dividing ring 5 to form a cavity, which forms a micro-perforated sound-absorbing structure with the small holes 4 on the inner layer bellows 3.

[0032] The sound absorption coefficient of micro-perforated sound absorption can be calculated by the following formula:

[0033]

[0034] in:

[0035] α is the sound absorption coefficient;

[0036] R is the acoustic resistance, which is related to the hole diameter, hole spacing and plate thickness of the perforated plate;

[0037] X is the acoustic reactance, which is related to the hole diameter, hole spacing and plate thickness of the perforated plate;

[0038] k is the wave number, Where f is the frequency and c is the speed of sound;

[0039] D is the cavity depth.

[0040] When the variable speed airflow passes through the double-layer metal bellows, the size of the small holes 4 and the cavity depth will change, thereby increasing the sound absorption coefficient of the structure and improving the sound absorption effect of the double-layer metal bellows.

[0041] The present invention is not limited to the above-described embodiments. Any structural changes made under the guidance of the present invention, which have the same or similar technical solutions as the present invention, should be understood to fall within the scope of protection of the present invention. The technologies, shapes, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A double-layer metal bellows with sound absorption function, comprising an outer bellows (1) and an inner bellows (3), characterized in that: The outer layer corrugated pipe (1) is sleeved on the outside of the inner layer corrugated pipe (3).

2. The double-layer metal bellows with sound absorption function according to claim 1, characterized in that: The outer layer bellows (1) and the inner layer bellows (3) are both made of metal.

3. The double-layer metal bellows with sound absorption function according to claim 1, characterized in that: The outer layer corrugated tube (1) and the inner layer corrugated tube (3) are different in inner diameter, thickness and corrugation type.

4. The double-layer metal bellows with sound absorption function according to claim 1, characterized in that: A cavity dividing ring (5) is provided between the outer layer corrugated tube (1) and the inner layer corrugated tube (3) near the center, and the cavity dividing ring (5) is provided in multiple groups.

5. The double-layer metal bellows with sound absorption function as claimed in claim 4, characterized in that: The cavity dividing ring (5) is composed of a low-rigidity outer ring (7) and a high-rigidity inner ring (8), the top of the low-rigidity outer ring (7) is in contact with the inner side of the outer bellows (1), and the inner layer of the high-rigidity inner ring (8) is in contact with the outer side of the inner bellows (1).

6. The double-layer metal bellows with sound absorption function according to claim 5, characterized in that: Support rings (2) are provided between the outer layer corrugated pipe (1) and the inner layer corrugated pipe (3) near both ends.

7. The double-layer metal bellows with sound absorption function according to claim 6, characterized in that: The surface of the inner layer corrugated tube (3) is provided with a plurality of groups of small holes (4), and the size of the small holes (4) can be varied.

8. The double-layer metal bellows with sound absorption function according to claim 7, characterized in that: A guide plate (6) is provided on the inner side of the inner layer corrugated tube (3), and the guide plate (6) extends in the direction of the air flow.

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