Metamaterial silencer for vehicle

Abstract

The utility model discloses a vehicle metamaterial silencer, relates to the automobile noise control technical field, including outer cylinder, inner core body and two end cover, outer cylinder is used for installing at the vehicle end, outer cylinder and inner core body are both variable diameter design and hollow inside, outer cylinder is sleeved on the outer circumference of inner core body, outer cylinder can carry out circumferential limit to the inner core body, the two end cover is equipped with the outer cylinder, the inner core body is equipped with the two end cover, the two end cover is equipped with the two end cover. A plurality of sound absorption small holes are formed in the side wall of the inner core body, the two end covers are packaged at the two ends of the outer barrel body respectively, the two end covers are each provided with a connecting pipe, one connecting pipe is used for being connected with an engine exhaust pipe, and the other connecting pipe is used for being connected with a tail bent pipe of an exhaust system. A cavity formed after the outer cylinder body, the inner core body and the two end covers are assembled forms a Helmholtz resonant cavity and an expansion cavity. The exhaust pressure drop of the exhaust system of the hydrogen fuel cell vehicle cannot be excessively increased while noise is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of automobile noise control, in particular to a metamaterial muffler for a vehicle. Background Art

[0002] With the development of the new energy vehicle industry, hydrogen fuel cell vehicles are gradually being promoted towards commercialization. The emergence of this new energy product has made it impossible for some existing parts to fully provide effective matching effects. For example, the emissions of hydrogen fuel cell vehicles are water vapor (condensed water), air that does not participate in the reaction, and a small amount of hydrogen. The cleanness of the emissions does not require a complex post-processing system. The exhaust system can directly use a traditional resistive, reactive or impedance composite muffler structure. However, the emitted water vapor (condensed water) will block the pores of the filler after entering the resistive muffler, resulting in low noise reduction efficiency and poor exhaust. The reactive muffler has a weak ability to eliminate broadband high-frequency sounds, so it is difficult for the traditional muffler to achieve the muffler effect, and at the same time affects the pressure loss of the exhaust system, which in turn affects the power level of the entire vehicle.

[0003] Acoustic metamaterial technology is a kind of artificially designed periodic structure with specific functions. It does not rely on the properties of the material itself, but can exert extraordinary physical properties and show excellent performance in noise control. Therefore, how to use the design theory of acoustic metamaterials and apply acoustic metamaterials to the noise reduction of mufflers is a technical problem that needs to be solved urgently. Utility Model Content

[0004] The purpose of the utility model is to provide a metamaterial muffler for a vehicle to solve the problems existing in the above-mentioned prior art, and at the same time, reduce noise without excessively increasing the tail exhaust pressure drop of the exhaust system of a hydrogen fuel cell vehicle.

[0005] To achieve the above purpose, the utility model provides the following solutions:

[0006] The utility model provides a metamaterial muffler for a vehicle, comprising an outer cylinder, an inner core and two end covers, wherein the outer cylinder is used to be installed at the vehicle end, the outer cylinder and the inner core are both of variable diameter design and hollow inside, the outer cylinder is sleeved on the outer periphery of the inner core, and the outer cylinder can limit the inner core circumferentially, a plurality of small sound-absorbing holes are arranged on the side wall of the inner core, the two end covers are respectively packaged at the two ends of the outer cylinder, and each of the two end covers is provided with a connecting pipe, one of the connecting pipes is used to connect to the engine exhaust pipe, and the other connecting pipe is used to connect to the tail elbow of the exhaust system, and the cavity after the outer cylinder, the inner core and the two end covers are assembled forms a Helmholtz resonance cavity and an expansion cavity.

[0007] Preferably, the outer cylinder body includes a small cylinder body and a large cylinder body. One end of the small cylinder body and one end of the large cylinder body are integrally formed. Both the small cylinder body and the large cylinder body are hollow cylinders, and the inner diameter of the small cylinder body is smaller than that of the large cylinder body. The two end covers are a large end cover and a small end cover respectively. The large end cover is detachably connected to the end of the large cylinder body far from the small cylinder body, and the small end cover is detachably connected to the end of the small cylinder body far from the large cylinder body. The connecting pipe on the small cylinder body is used to connect the engine exhaust pipe, and the connecting pipe on the large cylinder body is used to connect the tail elbow of the exhaust system.

[0008] Preferably, the inner core body includes a small core body and a large core body that are not connected to each other. The small core body is limitedly connected inside the small cylinder body. The small core body includes two small core body units. The two small core body units are symmetrically arranged. Each small core body unit includes a plurality of semi-circular funnel-shaped small shell units arranged in sequence along the axial direction of the small cylinder body. Adjacent small shell units are integrally formed. When the two small core body units are buckled, a plurality of funnel-shaped small shells arranged along the axial direction of the small cylinder body can be formed. In the gas flow direction, the maximum outer diameters of the plurality of funnel-shaped small shells gradually decrease, and the diameters of each funnel-shaped small shell gradually decrease. A plurality of circles of steps corresponding to each funnel-shaped small shell are provided on the inner wall of the small cylinder body. The large core body is limitedly connected inside the large cylinder body. The large core body includes two large core body units. The two large core body units are symmetrically arranged. Each large core body unit includes a plurality of semi-circular funnel-shaped large shell units arranged in sequence along the axial direction of the large cylinder body. Adjacent large shell units are integrally formed. When the two large core body units are buckled, a plurality of funnel-shaped large shells arranged along the axial direction of the large cylinder body can be formed. In the gas flow direction, the maximum outer diameters of the plurality of funnel-shaped large shells gradually increase, and the diameters of each funnel-shaped large shell gradually decrease. A plurality of sound absorption holes are circumferentially provided at the connection of adjacent funnel-shaped small shells.

[0009] Preferably, a first limiting element is provided at the upper end of the small shell unit located above and close to the small end cover side. The first limiting element is used for limited connection with the inner wall of the small cylinder body. A second limiting element is provided at the upper end and both sides of each large shell unit located above. The second limiting element is used for limited connection with the inner wall of the large cylinder body.

[0010] Preferably, the first limiting element is a convex platform, and a concave hole for cooperating with the convex platform is provided at the position of the inner wall of the small cylinder body corresponding to the first limiting element. The second limiting element is a limiting plane, and a limiting platform for cooperating with the limiting plane is provided at the position of the inner wall of the large cylinder body corresponding to the limiting plane.

[0011] Preferably, leak holes are provided at the lower ends of the lower small housing units and the lower ends of the lower large housing units; drain grooves are provided at the lower ends of the large cylinder and the small cylinder, and drain nozzles are provided on the bottom surfaces of the drain grooves. The leak holes can communicate the inside of the inner core body with the drain grooves, and the drain nozzles can communicate the drain grooves with the outside.

[0012] Preferably, a plurality of fixed hole seats are integrally formed on the outer periphery of the end cover and at both ends of the outer cylinder. The fixed hole seats on the end cover are connected to the fixed hole seats at the ends of the outer cylinder by screws, and a sealant is used to bond between the inner side of the end cover and the outer cylinder.

[0013] Preferably, a support is fixed to the upper end of the outer cylinder, and the support is connected to the vehicle end by bolts; drain holes are provided on the support, and the drain holes can drain the accumulated liquid inside the support.

[0014] Preferably, a plurality of reinforcing ribs are provided on the outer wall of the outer cylinder.

[0015] Preferably, the outer cylinder, the inner core body and the end cover are all integrally injection molded and are all made of plastic alloy.

[0016] The present utility model has achieved the following technical effects compared with the prior art:

[0017] The vehicle-mounted metamaterial muffler provided by the present utility model has an outer cylinder for installation at the vehicle end to reduce the noise of the exhaust system of a hydrogen fuel cell vehicle. Both the outer cylinder and the inner core body are of variable diameter design and hollow inside. The outer cylinder is sleeved on the outer periphery of the inner core body, and the outer cylinder can circumferentially limit the inner core body to prevent relative rotation between the outer cylinder and the inner cylinder during operation, which affects the stability of the overall structure. A plurality of sound absorption small holes are provided on the side wall of the inner core body. Two end covers are respectively sealed at both ends of the outer cylinder, and each of the two end covers is provided with a connecting pipe. One connecting pipe is used to connect the engine exhaust pipe, and the other connecting pipe is used to connect the tail elbow of the exhaust system. The cavities formed after the assembly of the outer cylinder, the inner core body and the two end covers form a Helmholtz resonance cavity and an expansion cavity, that is, a sub-wavelength size sound absorption structure. With the arrangement of the sound absorption small holes, when the gas flows in the cavity, the sound wave oscillates and dissipates and cancels each other out in the structure, achieving broadband full-frequency noise reduction. Furthermore, while eliminating the sound, it does not excessively increase the tail pipe pressure drop of the exhaust system of the hydrogen fuel cell vehicle. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 Structural schematic diagram of the vehicle - used metamaterial muffler in the present invention;

[0020] Figure 2 Cross - sectional view of the vehicle - used metamaterial muffler in the present invention;

[0021] Figure 3 Cross - sectional view of the outer cylinder in the present invention;

[0022] Figure 4 Exploded view of the structure of the vehicle - used metamaterial muffler in the present invention;

[0023] Figure 5 Side view of the small end cap in the present invention;

[0024] Figure 6 Cross - sectional view of the small core body in the present invention;

[0025] Figure 7 Cross - sectional view of the large core body in the present invention;

[0026] In the figure: 1 - outer cylinder, 2 - small cylinder, 3 - large cylinder, 4 - reinforcing rib, 5 - small end cap, 6 - large end cap, 7 - connecting pipe, 8 - fixed hole seat, 9 - support, 10 - small core body, 11 - large core body, 12 - water leakage hole, 13 - sound absorption small hole, 14 - screw. Specific embodiments

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide a vehicle - used metamaterial muffler to solve the problems existing in the prior art, and while reducing noise, it will not overly increase the tail - pipe pressure drop of the exhaust system of a hydrogen fuel cell vehicle.

[0029] To make the above - mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0030] As Figures 1-7 shown, this embodiment provides a vehicle - used metamaterial muffler, which includes an outer cylinder 1, a core body, and two end caps. The outer cylinder 1 is used to be installed at the vehicle end to reduce noise in the exhaust system of a hydrogen fuel cell vehicle. Both the outer cylinder 1 and the core body are of variable - diameter design and hollow inside. The outer cylinder 1 is sleeved around the outer periphery of the core body, and the outer cylinder 1 can circumferentially limit the core body to prevent relative rotation between the outer cylinder 1 and the inner cylinder during operation, which affects the stability of the overall structure. A plurality of sound - absorbing small holes 13 are provided on the side wall of the core body. The two end caps are respectively sealed at both ends of the outer cylinder 1, and each of the two end caps is provided with a connecting pipe 7. One of the connecting pipes 7 is used to connect to the engine exhaust pipe, and the other connecting pipe 7 is used to connect to the tail bend of the exhaust system. The cavity formed after the assembly of the outer cylinder 1, the core body, and the two end caps forms a Helmholtz resonance cavity and an expansion cavity, that is, a sub - wavelength - sized sound - absorbing structure. With the arrangement of the sound - absorbing small holes 13, when the gas flows in the cavity, the sound wave oscillates and dissipates in the structure, and the coherent cancellation occurs, achieving broadband full - frequency noise reduction. Moreover, there is no need to set sound - absorbing cotton. While eliminating noise, it does not excessively increase the tail - end pressure drop of the exhaust system of the hydrogen fuel cell vehicle.

[0031] Specifically, the outer cylinder 1 includes a small cylinder 2 and a large cylinder 3. One end of the small cylinder 2 and one end of the large cylinder 3 are integrally formed, and both the small cylinder 2 and the large cylinder 3 are hollow cylinders, which is convenient for installing the large core body 11 and the small core body 10. The inner diameter of the small cylinder 2 is smaller than that of the large cylinder 3, so as to be able to adapt to the small core body 10 and the large core body 11 respectively. The two end caps are respectively a large end cap 6 and a small end cap 5. The large end cap 6 is detachably connected to the large cylinder 3 at the end far from the small cylinder 2, and the small end cap 5 is detachably connected to the small cylinder 2 at the end far from the large cylinder 3. The connecting pipe 7 on the small cylinder 2 is used to connect to the engine exhaust pipe through a clamp, and the connecting pipe 7 on the large cylinder 3 is used to connect to the tail bend of the exhaust system through a clamp to realize the inlet and outlet of gas. The diameters of the two connecting pipes 7 are the same, realizing a hollow straight - tube type from the inlet end to the outlet end, and the system pressure drop and flow resistance are low.

[0032] The inner core body includes a small core body 10 and a large core body 11 that are not connected to each other. The small core body 10 is limit-connected within the small cylinder 2. Both the large core body 11 and the small core body 10 are of split design, and the split parts of the large core body 11 and the small core body 10 are all joined by vibration friction welding or infrared welding or gluing, which is convenient for processing. The small core body 10 includes two small core body units. The two small core body units are symmetrically arranged, and each small core body unit includes a plurality of semi-circular funnel-shaped small shell units arranged in sequence along the axial direction of the small cylinder 2, preferably eight. The adjacent small shell units are integrally formed. When the two small core body units are buckled together, a plurality of funnel-shaped small shells arranged along the axial direction of the small cylinder 2 can be formed, thereby forming a cavity structure with multiple periodic arrays. Each cavity structure can perform noise cancellation processing for a specific frequency band. In the gas flow direction, the maximum outer diameters of the plurality of funnel-shaped small shells gradually decrease, that is, the sizes of each funnel-shaped small shell are different, which is convenient for the small core body 10 to be installed through the opening side of the small cylinder 2. In the gas flow direction, the diameters of each funnel-shaped small shell gradually decrease, that is, the orientations of each funnel-shaped small shell are the same, and the openings all face the gas inlet direction. The inner wall of the small cylinder 2 is provided with multiple circles of steps corresponding to each funnel-shaped small shell to realize the assembly of the small cylinder 2 and the small core body 10; the large core body 11 is limit-connected within the large cylinder 3. The large core body 11 includes two large core body units. The two large core body units are symmetrically arranged, and each large core body unit includes a plurality of semi-circular funnel-shaped large shell units arranged in sequence along the axial direction of the large cylinder 3, preferably three, and are formed by sequential array through inner and outer connecting ribs. The adjacent large shell units are integrally formed. When the two large core body units are buckled together, a plurality of funnel-shaped large shells arranged along the axial direction of the large cylinder 3 can be formed, thereby forming a cavity structure with multiple periodic arrays. Each cavity structure can perform noise cancellation processing for a specific frequency band, achieving broadband full-frequency noise reduction. The use of an artificially designed metamaterial structure can achieve large-band noise cancellation and ensure the performance of the hydrogen fuel cell with a low pressure loss.

[0033] In this embodiment, the cavity formed after the assembly of the small end cap 5, the small core body 10 and the small cylinder 2 is the first type of noise cancellation structure, which specifically includes a circumferential non-regular cross-section Helmholtz resonator and a conical expansion cavity distributed radially. The series cavity is formed by the axial array of eight groups of combined cavities, realizing the control of the exhaust noise in the medium and high frequency bands.

[0034] In this embodiment, the cavity formed after the assembly of the large end cap 6, the large core body 11 and the large cylinder 3 is the second type of noise cancellation structure, which specifically includes an annular Helmholtz resonator with an irregular cross-section and a conical frustum expansion cavity. After the three groups of structures are axially distributed, a series cavity structure is formed, achieving better control of the exhaust noise in the medium and low frequencies.

[0035] In the gas flow direction, the maximum outer diameters of multiple funnel-shaped large shells increase in sequence, that is, the sizes of each funnel-shaped large shell are different, which facilitates the loading of the large core body 11 through the opening side of the large cylinder body 3. And in the gas flow direction, the diameters of each funnel-shaped large shell gradually decrease, that is, the orientations of each funnel-shaped large shell are the same, and the openings all face the gas inlet direction; a plurality of sound absorption holes 13 are circumferentially arranged at the connection of adjacent funnel-shaped small shells. Preferably, twelve groups of sound absorption holes 13 with a diameter of 1.5 mm are arranged at each connection. Through the above shape design, the structure of the vehicle-use metamaterial muffler has an order characteristic, meeting the full-frequency band noise reduction requirements of the exhaust system; using the metamaterial design theory, the cavity formed by the above physical structure is a sub-wavelength size sound absorption system, specifically a circumferential non-regular cross-section Helmholtz resonator and a conical expansion cavity distributed radially, and then a series of cavities are formed by axially arranging the cavity structures in an array to realize the noise control of the full-frequency band of the exhaust system.

[0036] In this embodiment, a first limiting element is provided at the upper end of the small shell unit located above and close to the small end cover 5. The first limiting element is used for limiting connection with the inner wall of the small cylinder body 2. Then, through the cooperation between the first limiting element and the inner wall of the small cylinder body 2, the rotation of the small core body 10 relative to the small cylinder body 2 is restricted. At the upper end and both sides of each large shell unit located above, a second limiting element is provided. The second limiting element is used for limiting connection with the inner wall of the large cylinder body 3. Then, through the cooperation between the second limiting element and the inner wall of the large cylinder body 3, the rotation of the large core body 11 relative to the large cylinder body 3 is restricted.

[0037] The first limiting element is a convex platform. At the position of the inner wall of the small cylinder body 2 corresponding to the first limiting element, a concave hole cooperating with the convex platform is provided. Then, by inserting the convex platform into the concave hole, the circumferential limitation of the small cylinder body 2 on the small core body 10 is realized; the second limiting element is a limiting plane. At the position of the inner wall of the large cylinder body 3 corresponding to the limiting plane, a limiting platform cooperating with the limiting plane is provided. Through the fitting of the limiting plane and the limiting platform, the circumferential limitation of the large cylinder body 3 on the large core body 11 is realized. The length of the limiting plane is preferably 27.5 mm.

[0038] Leakage holes 12 are provided at the lower ends of each small shell unit located below and at the lower ends of each large shell unit located below. The opening shape of the leakage holes 12 is a semi-circle with a diameter of 10 mm; drainage grooves are provided at the lower ends of the large cylinder body 3 and the small cylinder body 2. A drainage nozzle is provided at the bottom surface of the drainage groove. The leakage holes 12 can communicate the inside of the inner core body and the drainage groove, and the drainage nozzle can communicate the drainage groove and the outside, facilitating the derivation of the condensed water discharged by the hydrogen fuel cell.

[0039] In this embodiment, the leakage hole 12 at the lower end of the small core body 10 and the small cylinder body 2 form an integral first drainage structure; the leakage hole 12 at the lower end of the large core body 11 and the large cylinder body 3 form an integral second drainage structure.

[0040] A plurality of fixed hole seats 8 are integrally formed on the outer periphery of the end cap, and six holes are provided on one side. A plurality of fixed hole seats 8 are also integrally formed at the end of the outer cylinder body 1. The end cap is inserted into the outer cylinder body 1, and the inner side of the end cap and the outer cylinder body 1 are bonded with sealant. Align the screw 14 hole positions of the two components, and then connect the fixed hole seats 8 on the end cap and the fixed hole seats 8 on the outer cylinder body 1 with screws 14. The screws 14 are self-tapping locking screws with a specification of M4*16.

[0041] A support 9 is fixed to the upper end of the outer cylinder body 1. There are four M10 bolt holes on the support 9. The support 9 is connected to the vehicle end by bolts. A support 9 is provided at the upper end of the large cylinder body 3 and the upper end of the small cylinder body 2 respectively; drainage holes are provided on the support 9, and the drainage holes can drain the accumulated liquid inside the support 9 to prevent the formation of accumulated liquid inside the partition of the support 9.

[0042] A plurality of reinforcing ribs 4 are provided on the outer wall of the outer cylinder body 1, which can effectively enhance the structural strength and stiffness of the outer cylinder body 1 and improve the durability and reliability of the product.

[0043] The outer cylinder body 1, the inner core body and the end cap are all integrally injection molded and are all made of plastic alloy, that is, PC / ABS alloy. Among them, the basic wall thickness of the outer cylinder body 1 is 3mm; the basic wall thickness of the small core body 10 is 2.5mm; the basic wall thickness of the large core body 11 is 2.5mm; the basic wall thickness of the end cap is 3mm.

[0044] In this embodiment, using the theory of metamaterial design, the sound-absorbing part adopts a mixed periodic arrangement of circumferential and axial types to achieve the sound-absorbing effect from low frequency to high frequency, and the average transmission loss in the full frequency band is greater than 30dB; at the same time, using a straight cylindrical pipe design structure, the flow resistance can be minimized, and the flow resistance is not greater than 1 / 3 of that of a conventional muffler under the same exhaust gas flow rate. Through the above design, this embodiment has the characteristics of small total assembly mass, wide noise reduction frequency band, and low pressure drop and flow resistance, and is suitable for the exhaust system of medium and low power segment hydrogen fuel cell vehicles.

[0045] The specific principle of the Helmholtz resonance cavity involved in this embodiment is as follows:

[0046] The Helmholtz resonance cavity is composed of two parts: a bottleneck and a cavity. Several important dimensional parameters determine its resonance frequency, specifically including: bottleneck length, bottleneck radius, and cavity volume.

[0047] The structure of the Helmholtz resonance cavity is similar to a mass-spring system. Its bottleneck air is analogous to a spring, and the cavity volume is analogous to a mass. After the main pipe inputs a sound pressure excitation, the sound wave enters the cavity from the neck opening, causing the gas at the neck opening to move back and forth to compress the gas in the cavity. When the sound wave frequency is consistent with the natural frequency of the resonance cavity structure, the resonance amplitude is the largest and the energy consumed is the most. The calculation formula for deriving the resonance frequency is as follows:

[0048]

[0049] Among them, A is the cross-sectional area of the bottleneck, V is the cavity volume, L is the bottleneck length, and c is the sound propagation speed in air. It can be seen from this formula that the larger the volume, the lower the resonance frequency. Since the vehicle-use metamaterial muffler in this embodiment is overall large-bandwidth noise reduction and low air resistance is also considered, it is designed into a conical cavity structure.

[0050] In the present utility model, specific examples are used to illustrate the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. A vehicle-mounted metamaterial muffler, characterized in that: It includes an outer cylinder, an inner core and two end caps. The outer cylinder is used to be installed at the end of a vehicle. Both the outer cylinder and the inner core are of variable diameter design and hollow inside. The outer cylinder is sleeved on the outer periphery of the inner core, and the outer cylinder can circumferentially limit the inner core. A plurality of sound absorption holes are provided on the side wall of the inner core. The two end caps are respectively encapsulated at both ends of the outer cylinder, and each of the two end caps is provided with a connecting pipe. One of the connecting pipes is used to connect the engine exhaust pipe, and the other connecting pipe is used to connect the tail elbow of the exhaust system. The cavity formed after the assembly of the outer cylinder, the inner core and the two end caps forms a Helmholtz resonance cavity and an expansion cavity.

2. The vehicle-use metamaterial muffler according to claim 1, wherein: The outer cylinder includes a small cylinder and a large cylinder. One end of the small cylinder and one end of the large cylinder are integrally formed, and both the small cylinder and the large cylinder are hollow cylindrical shapes. The inner diameter of the small cylinder is smaller than the inner diameter of the large cylinder. The two end caps are respectively a large end cap and a small end cap. The large end cap is detachably connected to the large cylinder at the end far from the small cylinder, and the small end cap is detachably connected to the small cylinder at the end far from the large cylinder. The connecting pipe on the small cylinder is used to connect the engine exhaust pipe, and the connecting pipe on the large cylinder is used to connect the tail elbow of the exhaust system.

3. The vehicle-use metamaterial muffler according to claim 2, wherein: The inner core includes a non-connected small core and a large core. The small core is limit-connected inside the small cylinder. The small core includes two small core units, and the two small core units are symmetrically arranged. Each of the small core units includes a plurality of semi-circular funnel-shaped small shell units arranged in sequence along the axial direction of the small cylinder. The adjacent small shell units are integrally formed. When the two small core units are buckled, a plurality of funnel-shaped small shells arranged along the axial direction of the small cylinder can be formed. In the gas flow direction, the maximum outer diameters of the plurality of funnel-shaped small shells gradually decrease, and the diameters of each of the funnel-shaped small shells gradually decrease. A plurality of circles of steps corresponding to each of the funnel-shaped small shells are provided on the inner wall of the small cylinder. The large core is limit-connected inside the large cylinder. The large core includes two large core units, and the two large core units are symmetrically arranged. Each of the large core units includes a plurality of semi-circular funnel-shaped large shell units arranged in sequence along the axial direction of the large cylinder. The adjacent large shell units are integrally formed. When the two large core units are buckled, a plurality of funnel-shaped large shells arranged along the axial direction of the large cylinder can be formed. In the gas flow direction, the maximum outer diameters of the plurality of funnel-shaped large shells gradually increase, and the diameters of each of the funnel-shaped large shells gradually decrease. A plurality of the sound absorption holes are circumferentially provided at the connection of the adjacent funnel-shaped small shells.

4. The vehicle-use metamaterial muffler according to claim 3, characterized in that: A first limiting element is provided at the upper end of the small shell unit located above and close to the side of the small end cap. The first limiting element is used for limit-connection with the inner wall of the small cylinder. A second limiting element is provided at the upper end and both sides of each of the large shell units located above. The second limiting element is used for limit-connection with the inner wall of the large cylinder.

5. The vehicle-mounted metamaterial muffler according to claim 4, characterized in that: The first limiting element is a boss, and a concave hole cooperating with the boss is provided at a position on the inner wall of the small cylinder corresponding to the first limiting element; the second limiting element is a limiting plane, and a limiting platform cooperating with the limiting plane is provided at a position on the inner wall of the large cylinder corresponding to the limiting plane.

6. The vehicle-use metamaterial muffler according to claim 3, wherein: Leakage holes are provided at the lower ends of the small housing units located below and the lower ends of the large housing units located below; drain grooves are provided at the lower ends of the large cylinder and the small cylinder, a drain nozzle is provided at the bottom surface of the drain groove, the leakage holes can communicate the interior of the inner core body and the drain groove, and the drain nozzle can communicate the drain groove and the outside.

7. The vehicle-use metamaterial muffler according to claim 1, wherein: A plurality of fixing hole seats are integrally formed on the outer periphery of the end cover and at both ends of the outer cylinder, the fixing hole seats on the end cover and the fixing hole seats at the end of the outer cylinder are connected by screws, and a sealant is used for bonding between the inner side of the end cover and the outer cylinder.

8. The vehicle-mounted metamaterial muffler according to claim 1, characterized in that: A support is fixed at the upper end of the outer cylinder, the support is connected to the vehicle end by bolts; drain holes are provided on the support, and the drain holes can drain the accumulated liquid inside the support.

9. The vehicle-mounted metamaterial muffler according to claim 1, wherein: A plurality of reinforcing ribs are provided on the outer wall of the outer cylinder.

10. The vehicle-use metamaterial muffler according to claim 1, characterized in that: The outer cylinder, the inner core body and the end cover are all integrally injection molded and are all made of plastic alloy.

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